id int64 39 79M | url stringlengths 31 227 | text stringlengths 6 334k | source stringlengths 1 150 ⌀ | categories listlengths 1 6 | token_count int64 3 71.8k | subcategories listlengths 0 30 |
|---|---|---|---|---|---|---|
78,058,995 | https://en.wikipedia.org/wiki/Explanatory%20indispensability%20argument | The explanatory indispensability argument is an argument in the philosophy of mathematics for the existence of mathematical objects. It claims that rationally we should believe in mathematical objects such as numbers because they are indispensable to scientific explanations of empirical phenomena. An altered form of the Quine–Putnam indispensability argument, it differs from that argument in its increased focus on specific explanations instead of whole theories and in its shift towards inference to the best explanation as a justification for belief in mathematical objects rather than confirmational holism.
Specific explanations proposed as examples of mathematical explanations in science include why periodical cicadas have prime-numbered life cycles, why bee honeycomb has a hexagonal structure, and the solution to the Seven Bridges of Königsberg problem. Objections to the argument include the idea that mathematics is only used as a representational device, even when it features in scientific explanations; that mathematics does not need to be true to be explanatory because it could be a useful fiction; and that the argument is circular and so begs the question in favour of mathematical objects.
Background
The explanatory indispensability argument is an altered form of the Quine–Putnam indispensability argument first raised by W. V. Quine and Hilary Putnam in the 1960s and 1970s. The Quine–Putnam indispensability argument supports the conclusion that mathematical objects exist with the idea that mathematics is indispensable to the best scientific theories. It relies on the view, called confirmational holism, that scientific theories are confirmed as wholes, and that the confirmations of science extend to the mathematics it makes use of.
The reliance of the Quine–Putnam argument on confirmational holism is controversial, and it has faced influential challenges from Penelope Maddy and Elliott Sober. The argument has also been criticized for failing to specify the way in which mathematics is indispensable to science; according to Joseph Melia, one would only need to believe in mathematics if it is indispensable in the right way. Specifically, it needs to be indispensable to scientific explanations for it to be as strongly justified as theoretical entities such as electrons. This claim by Melia arose through a debate with Mark Colyvan in the early 2000s over the argument, with Colyvan claiming that mathematics enhances the explanatory power of science. Inspired by this debate, Alan Baker developed an explicitly explanatory form of the indispensability argument, which he termed the enhanced indispensability argument. He was also motivated by the objections against confirmational holism; his formulation aimed to replace confirmational holism with an inference to the best explanation. As such, it is more focused on individual scientific explanations than whole theories.
Among Baker's influences was Hartry Field, who has been credited with being the first person to draw a connection between indispensability arguments and explanation. Baker cited Field as originating an explanatory form of the argument, although Sorin Bangu states that Field merely alluded to such an argument without fully developing it, and Russell Marcus argues he was discussing explanation within the context of the original Quine–Putnam indispensability argument rather than suggesting a new explanatory indispensability argument. According to Marcus, Colyvan's discussion of explanatory power was also initially restricted to its role within the Quine–Putnam indispensability argument. He credits Baker with originating the explanatory indispensability argument. Others, such as Christopher Pincock, place the beginning of the argument's development with Colyvan while noting that Baker sharpened its explanatory focus.
Overview of the argument
A standard formulation of the explanatory indispensability argument is given as follows:
We ought rationally to believe in the existence of any entity which plays an indispensable explanatory role in our best scientific theories.
Mathematical objects play an indispensable explanatory role in science.
Therefore, we ought rationally to believe in the existence of mathematical objects.
The argument is premised on the idea that inference to the best explanation, which is often used to justify theoretical entities such as electrons, can provide a similar kind of support for mathematical objects. It also requires that there are genuinely mathematical explanations in science. For explanations to be genuinely mathematical, it is not enough that they are expressed with the help of mathematics. Instead, mathematics must play an essential part in the explanatory work. Given the argument's reliance on the existence of such explanations, much of the discussion on it has focused on evaluating specific case studies to assess if they are genuine mathematical explanations or not.
Case studies
Periodical cicadas
The most influential case study is the example of periodical cicadas provided by Baker. Periodical cicadas are a type of insect that usually have life cycles of 13 or 17 years. It is hypothesized that this is an evolutionary advantage because 13 and 17 are prime numbers. Because prime numbers have no non-trivial factors, this means it is less likely that periodic predators and other competing species of cicada can synchronize with periodic cicadas' life cycles. Baker argues that this is an explanation in which mathematics, specifically number theory, plays a key role in explaining an empirical phenomenon.
A number of non-mathematical explanations have been proposed for the length of periodical cicadas' life cycles. For example, a prominent alternative explanation claims that prime-numbered life cycles could have emerged from non-prime life cycles due to developmental delays. This hypothesis is supported by the fact that there are many other species of cicada that have non-prime life cycles, and that developmental changes with 4-year periods have often been observed in periodical cicadas. Some philosophers have also argued that the concept of primeness in the case study by Baker can be replaced with a non-numeric concept of "intersection-minimizing periods", although Baker has argued that this would reduce the generality and depth of the explanation. Others, such as Chris Daly and Simon Langford, argue that using years as a unit of measurement rather than months or seasons is arbitrary; Baker and Colyvan argue that years are an appropriate unit of time for biological development and are the unit used by biologists.
The case study has also been criticized for assuming that periodical cicadas have had predators with periodic life cycles in their evolutionary history. Baker has responded to this worry by arguing that it would be impossible to provide direct evidence that periodical cicadas have had periodic predators because "periodicity is not something that can be gleaned from the fossil record". However, he has attempted to make the claim more plausible by arguing that ecological constraints could have restricted the range of the cicadas' possible life cycles, lessening the requirements on periodic predators for the case study to remain mathematically sound. This problem can also be avoided by focusing on other ways in which the prime life cycles could be explanatorily relevant, such as avoidance of competing species of cicada or periodic migration of predators.
Bee honeycomb
Another prominent case study suggested by Aidan Lyon and Colyvan concerns the hexagonal structure of bee honeycomb. Lyon and Colyvan contend that the hexagonal structure of bee honeycomb can be explained by the mathematical proof of the honeycomb conjecture, which states that hexagons are the most efficient regular tiling of the plane. The explanation goes that there is an evolutionary pressure for honeybees to conserve wax in the construction of their combs, so the efficiency of the hexagonal grid explains why it is selected for.
The explanation based on the honeycomb conjecture is potentially incomplete because the proof is a solution to a tiling problem in two dimensions, and disregards the 3D structure of comb cells. Furthermore, many mathematicians do not see the proof of the honeycomb conjecture as an explanatory proof as it employs concepts outside of geometry to establish a geometrical result, although Baker argues that the proof need not be explanatory for the theorem to feature in genuine explanations in science. It is also controversial amongst philosophers whether the subject matter of geometry is purely mathematical, or whether it concerns physical space and structures, leading them to question if the explanation is truly mathematical.
There are also non-mathematical explanations for the honeycomb case study. Darwin believed that the hexagonal shape of bee combs was the result of tightly packed spherical cells being pushed together and pressed into hexagons, with bees fixing breakages with flat surfaces of wax further contributing to a hexagonal shape. More modern presentations hold that the shape of honeycomb is due to the flow of molten wax during the construction process.
Others
Another key example is the Seven Bridges of Königsberg, which concerns the impossibility of crossing each of the historical seven bridges in the Prussian city of Königsberg a single time in a continuous walk around the city. The explanation was found by Leonhard Euler in 1735 when he considered whether such a journey was possible. Euler's solution involved abstracting away from the concrete details of the problem to a mathematical representation in the form of a graph, with nodes representing landmasses and lines representing bridges. He reasoned that for each landmass, unless it is a starting or ending point, there must be a path to both enter and exit it. Therefore, there must be at most two nodes in the graph with an uneven number of lines connected to them for such a journey to be possible. But this is not the case for the graph representing the seven bridges in Königsberg, so it is mathematically impossible to cross all seven without crossing over one of the bridges multiple times.
The existence at any particular time of antipodal points on the Earth's surface with equal temperature and pressure has been cited as another example. According to Colyvan, this is explained by the Borsuk–Ulam theorem, which entails that for any physical property that varies continuously across the surface of a sphere, there are antipodal points on that sphere with equal values of that property. In response to this example, Baker has argued that it is a prediction rather than an explanation because antipodal points with equal pressure and temperature have not already been measured. Mary Leng also questions whether it is appropriate to model temperature or pressure as continuous functions across individual points on the Earth's surface. Other examples proposed by Colyvan include geometrical explanations for Lorentz contraction and gravitational lensing. Baker and Melia have objected to the geometrical aspects of these explanations, which could be interpreted physically instead of mathematically.
A key class of mathematical explanations is solutions to optimization problems, which includes the cicada and bee honeycomb case studies. In these cases, a certain feature is explained by showing that it is mathematically optimal. Such explanations are important in evolutionary biology, as mathematical demonstrations of optimality may help to explain why a given trait has been selected for, but also appear in other areas of science such as physics, engineering and economics. Some examples from evolutionary biology are sunflowers' seeds being arranged in a spiral pattern because it produces the densest packing of seeds, and marine predators engaging in Lévy walks because they minimize the average energy consumption required to find prey.
A number of case studies draw from dynamical systems. Marc Lange, for example, argues that the fact that double pendulums always have four or more equilibrium configurations can be explained by the configuration space of the system forming the surface of a torus, which must have at least four stationary points. Lyon and Colyvan point to the use of phase spaces and the Poincaré map to explain the behaviour of a Hénon–Heiles system, such as the stability of a star's orbit through a galaxy.
Some examples are drawn from outside science. For example, widely discussed cases include the explanation for why 23 strawberries cannot be divided equally amongst three people, why it is impossible to square the circle, and why it is impossible to untie a trefoil knot. However, it is unclear to what extent each of these cases are mathematical explanations of physical facts rather than either purely physical or purely mathematical explanations.
Objections
The main response to the explanatory indispensability argument, adopted by philosophers such as Melia, Daly, Langford, and Saatsi, is to deny there are genuinely mathematical explanations of empirical phenomena, instead framing the role of mathematics as representational or indexical. According to this response, if mathematics features in scientific explanations, its role is just to help pick out physical facts instead of contributing to the explanatory power of the explanation. Saatsi, and others including Jonathan Tallant and Davide Rizza, have rephrased case studies such as the periodic cicada example to remove reference to mathematical entities in an attempt to provide the true non-mathematical versions of these explanations. Defenders of the explanatory indispensability argument typically argue that the non-mathematical explanations provided are less general and modally weaker than mathematical explanations. They also argue that such explanations contradict scientific practice because scientists often accept the mathematical explanations as genuine scientific explanations.
Others, particularly mathematical fictionalists like Mary Leng and Stephen Yablo, have accepted that mathematics plays a genuinely explanatory role in science but argue it can play this role even if mathematical objects do not exist. They point to the use of idealizations like point masses that are used in scientific explanations but are not viewed as literally real. Leng argues that the explanatory power of mathematics can be explained by structural similarities between mathematical theory (viewed fictionally) and features of the real world. Yablo appeals to the expressive power of figurative language, claiming it shows that literally untrue statements can often convey more than literally true statements. Colyvan has challenged these types of responses by arguing that fictional or metaphorical language cannot play a role in genuine explanations: "when some piece of language is delivering an explanation, either that piece of language must be interpreted literally or the non-literal reading of the language in question stands proxy for the real explanation."
An objection advanced by Bangu states that the explanatory indispensability argument begs the question because it is circular. Bangu argues that examples like the periodic cicada case aim to explain statements that already contain mathematical content, namely the primeness of the cicadas' life cycles. But an inference to the best explanation assumes that the statement being explained is true, so the inclusion of mathematical concepts such as primeness assumes the truth of the mathematics in question. Baker has responded to this objection by arguing that the statements being explained in such case studies can be reformulated to remove reference to mathematical entities, leaving mathematics indispensable only to the explanation itself and not the thing being explained.
Notes
References
Citations
Sources
Further reading
Indispensability Arguments in Mathematics, Explanation in Mathematics, and Mathematical Explanation at PhilPapers
Philosophy of mathematics
Philosophical arguments | Explanatory indispensability argument | [
"Mathematics"
] | 3,076 | [
"nan"
] |
78,060,184 | https://en.wikipedia.org/wiki/Baffle%20blocks | Baffle blocks are concrete structures with different shapes, for example trapezoidal, used in flowing water to reduce its force. They are arranged in several rows in stilling basins. They are used in spillways and dams, in irrigation systems, to protect fishes in rivers with hydrotechnical installations, to improve sediment deposition, as a solution to scouring in hydraulic projects and in flood control.
See also
Slosh baffle
References
Fluid dynamics
Stormwater management
Soil erosion | Baffle blocks | [
"Chemistry",
"Engineering",
"Environmental_science"
] | 96 | [
"Water treatment",
"Stormwater management",
"Chemical engineering",
"Water pollution",
"Piping",
"Fluid dynamics stubs",
"Fluid dynamics"
] |
78,063,851 | https://en.wikipedia.org/wiki/Ammonium%20hexachloropalladate | Ammonium hexachloropalladate is an inorganic chemical compound with the chemical formula .
Synthesis
Ammonium hexachloropalladate can be made by passing chlorine through a suspension of ammonium tetrachloropalladate(II) in ammonium chloride solution:
The compound is precipitated from the palladium(IV) chloride solution with adding ammonium chloride:
Physical properties
Ammonium hexachloropalladate forms red-brown crystals of cubic system, space group Fm3m, cell parameters a = 0.983 nm, Z = 4.
It is slightly soluble in water.
Chemical properties
The compound decomposes upon heating to form ammonium tetrachloropalladate(II):
References
Chloro complexes
Ammonium compounds
Chlorometallates | Ammonium hexachloropalladate | [
"Chemistry"
] | 168 | [
"Ammonium compounds",
"Salts"
] |
78,064,657 | https://en.wikipedia.org/wiki/Generative%20AI%20pornography | Generative AI pornography or simply AI pornography refers to digitally created explicit content produced through generative artificial intelligence (AI) technologies. Unlike traditional pornography, which involves real actors and cameras, this content is synthesized entirely by AI algorithms. These algorithms, including Generative adversarial network (GANs) and text-to-image models, generate lifelike images, videos, or animations from textual descriptions or datasets.
History
The use of generative AI in the adult industry began in the late 2010s, initially focusing on AI-generated art, music, and visual content. This trend accelerated in 2022 with Stability AI's release of Stable Diffusion (SD), an open-source text-to-image model that enables users to generate images, including NSFW content, from text prompts using the LAION-Aesthetics subset of the LAION-5B dataset. Despite Stability AI's warnings against sexual imagery, SD's public release led to dedicated communities exploring both artistic and explicit content, sparking ethical debates over open-access AI and its use in adult media. By 2020, AI tools had advanced to generate highly realistic adult content, amplifying calls for regulation.
AI-generated influencers
One application of generative AI technology is the creation of AI-generated influencers on platforms such as OnlyFans and Instagram. These AI personas interact with users in ways that can mimic real human engagement, offering an entirely synthetic but convincing experience. While popular among niche audiences, these virtual influencers have prompted discussions about authenticity, consent, and the blurring line between human and AI-generated content, especially in adult entertainment.
The growth of AI porn sites
By 2023, websites dedicated to AI-generated adult content had gained traction, catering to audiences seeking customizable experiences. These platforms allow users to create or view AI-generated pornography tailored to their preferences. These platforms enable users to create or view AI-generated adult content appealing to different preferences through prompts and tags, customizing body type, facial features, and art styles. Tags further refine the output, creating niche and diverse content. Many sites feature extensive image libraries and continuous content feeds, combining personalization with discovery and enhancing user engagement. AI porn sites, therefore, attract those seeking unique or niche experiences, sparking debates on creativity and the ethical boundaries of AI in adult media.
Ethical concerns and misuse
The growth of generative AI pornography has also attracted some cause for criticism. AI technology can be exploited to create non-consensual pornographic material, posing risks similar to those seen with deepfake revenge porn and AI-generated NCII (Non-Consensual Intimate Image). A 2023 analysis found that 98% of deepfake videos online are pornographic, with 99% of the victims being women. Some famous celebrities victims of deepfake include Scarlett Johansson, Taylor Swift, and Maisie Williams.
OpenAI is exploring whether NSFW content, such as erotica, can be responsibly generated in age-appropriate contexts while maintaining its ban on deepfakes. This proposal has attracted criticism from child safety campaigners who argue it undermines OpenAI's mission to develop "safe and beneficial" AI. Additionally, the Internet Watch Foundation has raised concerns about AI being used to generate sexual abuse content involving children.
AI-generated NCII (AI Undress)
Several US states are taking actions against using deepfake apps and sharing them on the internet. In 2024, San Francisco filed a landmark lawsuit to shut down "undress" apps that allow users to generate non-consensual AI nude images, citing violations of state laws. The case aligns with California's recent legislation—SB 926, SB 942, and SB 981—championed by Senators Aisha Wahab and Josh Becker and signed by Governor Gavin Newsom. These bills aim to protect individuals from AI-generated explicit images by criminalizing non-consensual distribution, mandating disclosures, and empowering victims to report and remove harmful content from platforms.
Differences from deepfake pornography
While both generative AI pornography and deepfake pornography rely on synthetic media, they differ significantly in their methods and ethical considerations. Deepfake pornography typically involves altering existing footage of real individuals, often without their consent, using AI to superimpose faces or modify scenes. In contrast, generative AI pornography is created using algorithms, producing hyper-realistic content without the need to upload real pictures of people. Hany Farid, digital image analysis expert, also described the difference between "AI porn" and "deepfake porn."
References
Erotic art
Pornography
Pornography
Text-to-image generation | Generative AI pornography | [
"Engineering"
] | 958 | [
"Artificial intelligence engineering",
"Generative artificial intelligence"
] |
78,064,676 | https://en.wikipedia.org/wiki/Ammonium%20hexachloroselenate%28IV%29 | Ammonium hexachloroselenate(IV) is an inorganic chemical compound with the chemical formula .
Synthesis
Reaction of ammonium chloride and selenium tetrachloride:
Physical properties
Ammonium hexachloroselenate forms yellow crystals of the cubic system, space group Fm3m. Cell parameters are a = 0,9955 nm, Z = 4.
The compound demonstrates a phase transition at a temperature of 24 K.
It is soluble in water.
References
Selenites
Chloro complexes
Ammonium compounds
Chlorometallates | Ammonium hexachloroselenate(IV) | [
"Chemistry"
] | 115 | [
"Ammonium compounds",
"Salts"
] |
78,065,054 | https://en.wikipedia.org/wiki/Sebastian%20Hiller | Sebastian Hiller is a German and Swiss structural biologist and biophysicist. He has been teaching and researching at the Biozentrum of the University of Basel since 2010.
Life
Sebastian Hiller studied Interdisciplinary Natural Sciences at ETH Zurich and the University of Cambridge. He obtained his doctorate in 2006 in the laboratory of the Swiss Nobel Prize winner Kurt Wüthrich on methods of Nuclear Magnetic Resonance (NMR) spectroscopy. He conducted postdoctoral research with Gerhard Wagner at Harvard Medical School in Boston and with Beat Meier at ETH Zurich. In 2010, Sebastian Hiller was awarded an SNSF professorship at the Biozentrum of the University of Basel. In 2015 he was appointed Associate Professor and in 2022 Full Professor at the University of Basel.
Work
Sebastian Hiller uses NMR spectroscopy to investigate the structure and function of proteins, their interactions and underlying molecular mechanisms. By investigating the biophysical principles of molecular chaperone function, he was recently able to show how the state of α-synuclein in living cells is regulated, which plays a key role in the development of Parkinson's disease. He is also exploring the outer membrane protein biogenesis of Gram-negative bacteria and the way it can be targeted by novel antibiotics. By elucidating the natural compound darobactin's mode of action, his research serves as a basis for the rational design of new antibiotics, to help fight the world-wide antimicrobial resistance crisis. Other areas of research focus on mechanisms of bacterial cell signaling and mechanisms that control pyroptosis and chronic inflammation. Recent findings showed that the protein NINJ1 plays an important role in inflammatory reactions in the body and forms a molecular built-in breaking point on the cell membrane in preparation for cell death.
Awards and honors
2018 ICMRBS Founder's medal
2014 EMBO Young investigator
2011 ERC Starting grant
2010 SNSF Professorship
2008 SNSF Scholarship for young researchers
References
External links
Living people
Structural biologists
Harvard Medical School people
Biozentrum University of Basel
University of Basel alumni
Members of the European Molecular Biology Organization
Year of birth missing (living people) | Sebastian Hiller | [
"Chemistry"
] | 430 | [
"Structural biologists",
"Structural biology"
] |
78,066,049 | https://en.wikipedia.org/wiki/David%20Milne%20%28technologist%29 | Alastair David Milne is a Scottish technologist and founder and former CEO of the Wolfson Microelectronics company.
Early life and education
Milne was born in Edinburgh and attended George Watson's College. He pursued higher education in physics, earning a Bachelors from Heriot-Watt University in 1966 and an MSc and then PhD from the University of Bristol in 1968.
Career
In 1970, Milne joined the newly created Wolfson Industrial Liaison Unit at the University of Edinburgh. In 1973 he was promoted to director, renamed the unit as the Wolfson Microelectronics Institute and changed its focus to the design of semiconductor devices. In 1984, he co-founded the spinout company Wolfson Microelectronics which developed audio processing products for consumer electronics made by major manufacturers including Apple Inc and Samsung. The company became the first successful spin-out from a Scottish university and the second to be listed on the London Stock Exchange. Milne served as chief executive officer of Wolfson Microelectronics until 2007 and as non-executive director until 2012.
Milne has been active in the promotion of science and technology. He served as chairman of the Edinburgh International Science Festival between 2007 and 2022, and as trustee and chair of the James Clerk Maxwell Foundation.
Awards and recognition
In recognition of his contributions to technology and business he was awarded an OBE in 1984, Fellowship of the Royal Society of Edinburgh in 1991, Fellowship of the Institution of Engineering and Technology in 1992, and Fellowship of the Royal Academy of Engineering in 2002.
He was awarded the Royal Society of Edinburgh's Royal Medal in 2012 and honorary degrees from the University of Bristol and Heriot-Watt University in 2007, and the University of Edinburgh in 2008.
He has received several business awards including Scotland's Entrepreneur of the Year in 2003. He was inducted into the Scottish Engineering Hall of Fame in 2024.
References
Scottish Engineering Hall of Fame inductees
Fellows of the Royal Society of Edinburgh
1942 births
Living people
Alumni of Heriot-Watt University
People educated at George Watson's College
Alumni of the University of Bristol
People associated with the University of Edinburgh
Fellows of the Institution of Engineering and Technology
Fellows of the Royal Academy of Engineering
Scottish engineers
Scottish scientists | David Milne (technologist) | [
"Engineering"
] | 445 | [
"Institution of Engineering and Technology",
"Fellows of the Institution of Engineering and Technology"
] |
78,066,172 | https://en.wikipedia.org/wiki/Islamic%20Scientific%20Manuscripts%20Initiative | The Islamic Scientific Manuscripts Initiative (ISMI) () is an online database created to facilitate research into the history of mathematics sciences in the Islamic world, covering the period up to about 1350 CE. The initiative aims to provide accessible information on all Islamic manuscripts in the exact sciences, including astronomy, mathematics, theories, mathematical geography, music, mechanics, and related subjects.
It is an initiative of the Max Planck Institute for the History of Science (MPIWG), which is dedicated to advancing scientific knowledge and research.
References
Digital humanities projects
History of science
Islamic Golden Age
Manuscripts
Online databases | Islamic Scientific Manuscripts Initiative | [
"Technology"
] | 119 | [
"History of science",
"History of science and technology"
] |
78,067,163 | https://en.wikipedia.org/wiki/Alongshan%20virus | Alongshan virus (ALSV) is a tick-borne disease discovered in Alongshan, Inner Mongolia in 2017. It is a type of Jingmenvirus. It was discovered in ticks in Finland in 2019 and in Switzerland in 2022. In 2023, it was reported in ticks and animals in Lower Saxony.
References
Viruses
Tick-borne diseases | Alongshan virus | [
"Biology"
] | 73 | [
"Viruses",
"Tree of life (biology)",
"Microorganisms"
] |
78,069,556 | https://en.wikipedia.org/wiki/%CE%91-Methyltryptophan | α-Methyltryptophan (αMTP or α-MTP) is a synthetic tryptamine derivative, an artificial amino acid, and a prodrug of α-methylserotonin (αMS). It is the α-methylated derivative of tryptophan, while αMS is the α-methylated analogue of serotonin. αMTP has been suggested for potential therapeutic use in the treatment of conditions thought by some authors to be related to serotonin deficiency, such as depression. In labeled forms, αMTP is also used as a radiotracer in positron emission tomography (PET) imaging to assess serotonin synthesis and certain other processes.
αMS is a non-selective serotonin receptor agonist, including of the serotonin 5-HT2 receptors, and has been described as a "substitute neurotransmitter" of serotonin. However, whereas αMS itself is too hydrophilic to efficiently cross the blood–brain barrier, thus being peripherally selective, αMTP is able to cross the blood–brain barrier and, following transformation, deliver αMS into the brain.
Besides αMS, αMTP is also metabolized into α-methyltryptamine (αMT). αMT is a serotonin–norepinephrine–dopamine releasing agent, a non-selective serotonin receptor agonist, and a serotonergic psychedelic. However, αMT levels are much lower than those of αMS with αMTP and αMT is described as a minor metabolite of αMTP. In accordance, the behavioral effects of αMTP and αMT in animals are described as strikingly different. α-Methylmelatonin can also be formed in small amounts from αMTP, but the formation of this compound with αMTP in vivo appears to be negligible.
αMTP and αMS remain in the body for long amounts of time following a single dose of αMTP, whereas tryptophan results in only a short-lasting increase in brain serotonin levels. This is attributed to the resistance to metabolism of these compounds afforded by their α-methyl group. As such, αMTP might be advantageous for therapeutic purposes relative to tryptophan. αMTP is useful over tryptophan in PET imaging because αMTP, unlike tryptophan, is not incorporated as an amino acid into brain proteins, and because, unlike serotonin, αMS is not a substrate for monoamine oxidase (MAO) and hence remains in the brain for a much longer amount of time. The preceding limitations of tryptophan make its use in PET imaging in humans impossible, whereas αMTP is a viable agent for such purposes.
αMTP is first converted by tryptophan hydroxylase into α-methyl-5-hydroxytryptophan (αM-5-HTP or α-methyl-5-HTP), the α-methylated analogue of 5-hydroxytryptophan (5-HTP), prior to being decarboxylated by aromatic L-amino acid decarboxylase (AAAD) into αMS. αM-5-HTP has also been suggested for potential therapeutic use. However, αM-5-HTP is also a tyrosine hydroxylase inhibitor similarly to α-methyltyrosine, as well as an AAAD inhibitor, and has been found to deplete levels of brain norepinephrine in animals, although not levels of brain dopamine.
See also
O-Acetylbufotenine (O-acetyl-N,N-dimethylserotonin)
α-Methylphenylalanine
Metirosine (α-methyltyrosine)
Methyldopa (α-methyl-DOPA)
Neurotransmitter prodrug
References
Alpha-Alkyltryptamines
Alpha-Amino acids
Prodrugs
Serotonin receptor agonists | Α-Methyltryptophan | [
"Chemistry"
] | 852 | [
"Chemicals in medicine",
"Prodrugs"
] |
78,071,340 | https://en.wikipedia.org/wiki/Reinhard%20Diestel | Reinhard Diestel (born 1959) is a German mathematician specializing in graph theory, including the interplay among graph minors, matroid theory, tree decomposition, and infinite graphs. He holds the chair of discrete mathematics at the University of Hamburg.
Education and career
Diestel has a Ph.D. from the University of Cambridge in England, completed in 1986. His dissertation, Simplicial Decompositions and Universal Graphs, was supervised by Béla Bollobás.
He continued at Cambridge as a fellow of St. John's College, Cambridge until 1990. In 1994, he took a professorship at the Chemnitz University of Technology, and in 1999 he was given his current chair at the University of Hamburg.
At Hamburg, his doctoral students have included Daniela Kühn and Maya Stein.
Books
Diestel's books include:
Graph Decompositions: A Study in Infinite Graph Theory (Oxford University Press, 1990)
Graph Theory (Graduate Texts in Mathematics 173, Springer, 1997; 6th ed., 2024). Originally published in German as Graphentheorie (1996), and translated into Chinese, Japanese, and Russian.
Tangles: A Structural Approach to Artificial Intelligence in the Empirical Sciences (Cambridge University Press, 2024; )
References
External links
Home page
Graph Theory home page including free online preview version
1959 births
Living people
German mathematicians
Graph theorists
Alumni of the University of Cambridge
Fellows of St John's College, Cambridge
Academic staff of the Chemnitz University of Technology
Academic staff of the University of Hamburg | Reinhard Diestel | [
"Mathematics"
] | 306 | [
"Mathematical relations",
"Graph theory",
"Graph theorists"
] |
65,073,306 | https://en.wikipedia.org/wiki/Poisoning%20of%20Alexei%20Navalny | On 20 August 2020, Russian opposition leader and anti-corruption activist Alexei Navalny was poisoned with the Novichok nerve agent and as a result, he was hospitalized in serious condition. During a flight from Tomsk to Moscow, he became ill and was taken to a hospital in Omsk after an emergency landing there, and then, he was put in a coma. He was evacuated to the Charité hospital in Berlin, Germany, two days later. The use of the nerve agent was confirmed by five Organisation for the Prohibition of Chemical Weapons (OPCW) certified laboratories. On 7 September, doctors announced that they had taken Navalny out of the induced coma and that his condition had improved. He was discharged from the hospital on 22 September 2020. The OPCW said that a cholinesterase inhibitor from the Novichok group was found in Navalny's blood, urine, skin samples and his water bottle. At the same time, the OPCW report clarified that Navalny was poisoned with a new type of Novichok, which was not included in the list of controlled chemicals of the Chemical Weapons Convention.
Navalny accused President Vladimir Putin of being responsible for his poisoning, but the Kremlin said the accusations were "utterly unfounded" and "insulting". The Kremlin further alleged that Navalny was working for the CIA. The EU and the UK imposed sanctions over Navalny's poisoning on the director of the Russian Federal Security Service (FSB) Alexander Bortnikov, five other senior Russian officials, and the State Research Institute of Organic Chemistry and Technology (GosNIIOKhT). According to the EU, the poisoning of Navalny became possible "only with the consent of the Presidential Executive Office" and with the participation of the FSB. An investigation by Bellingcat and The Insider implicated agents from the FSB in Navalny's poisoning.
Russian prosecutors refused to open an official criminal investigation of the poisoning, claiming they found no sign that a crime had been committed, and the Kremlin denied involvement in the poisoning of Navalny.
Background
Alexei Navalny had previously been attacked by chemical substances. On 27 April 2017, Navalny was attacked by unknown assailants outside his office in the Anti-Corruption Foundation who sprayed brilliant green dye, possibly mixed with other components, into his face (see Zelyonka attack). He said he had lost 80 percent of the sight in his right eye. He also said that his doctor believed there was a second corrosive substance in the liquid and that "there is hope" the lost eyesight would be restored. He also alleged that the attacker was Aleksandr Petrunko, a man he claimed had ties with State Duma deputy speaker Pyotr Olegovich Tolstoy. Navalny accused the Kremlin of orchestrating the attack.
Another incident occurred in July 2019, when Navalny was arrested and imprisoned. On 28 July, he was hospitalized with severe damage to his eyes and skin. At the hospital, he was diagnosed with an allergic reaction, although this diagnosis was disputed by Anastasia Vasilyeva, one of his personal doctors. Vasilyeva questioned the diagnosis and suggested the possibility that Navalny's condition was the result of "the damaging effects of undetermined chemicals". On 29 July 2019, Navalny was discharged from hospital and taken back to prison, despite the objections of his personal physician who questioned the hospital's motives.
In August 2020, in the days leading up to the poisoning, Navalny had been publishing videos on his YouTube channel in which he expressed support for the pro-democracy 2020 Belarusian protests, which were triggered by the heavily contested 2020 Belarusian presidential election. Navalny had also written that the kind of 'revolution' that was taking place in neighboring Belarus would soon happen in Russia. Local news site Tayga.Info reported that during his Siberia trip, Navalny had been carrying out an investigation, as well as meeting local candidates and volunteers.
When asked if Navalny were preparing an exposé shortly before he became violently ill, Navalny ally Lyubov Sobol stated "I can't reveal all the details, but Navalny was on a work trip. He wasn't relaxing in the regions". The video investigation was later published by Navalny's team on 31 August.
It is assumed that Navalny was poisoned in a politically motivated attack as 'punishment' for his opposition work. According to The New York Times, experts expressed doubts that the Novichok agent would be used by someone other than a state-sponsored agent. Journalist and human rights advocate Anna Politkovskaya, known for her criticism of Putin and her coverage of the Second Chechen War, fell ill during a flight to cover the Beslan school siege in 2004 after drinking tea in an apparent poisoning attempt. She was later assassinated in 2006. In 2018, Pussy Riot activist Pyotr Verzilov was hospitalised in Moscow and later taken to the Charité hospital in Berlin a few days later for treatment which was organised by the Cinema for Peace Foundation after a suspected poisoning, where doctors at the hospital said it was "highly probable" that he was poisoned.
According to activist Ilya Chumakov, who met Navalny along with other supporters the day before his flight, when Navalny was asked why he was not dead, he said that his death would not be beneficial to Putin and that it would turn him into a hero.
Poisoning and treatment
On 20 August 2020, Navalny fell ill during a flight from Tomsk to Moscow and was hospitalised in the City Clinical Emergency Hospital No. 1 in Omsk (), where the plane had made an emergency landing. The change in his condition on the plane was sudden and violent, and video footage showed crew members on the flight scurrying towards him and Navalny crying loudly.
Afterwards, his spokeswoman said that he was in a coma and on a ventilator in the hospital. She also said that Navalny only drank tea since the morning and that it was suspected that something was added to his drink. The hospital said that he was in a stable but serious condition, and after initially acknowledging that Navalny had probably been poisoned, the hospital's deputy chief physician told reporters that poisoning was "one scenario among many" being considered. Although doctors in Russia initially suggested he suffered from a metabolic disorder caused by low blood sugar, they later stated that he had most likely been poisoned by antipsychotics or neuroleptics and that industrial chemicals such as 2-ethylhexyl diphenyl phosphate were found. A photograph on social media taken by a supporter appeared to show Navalny drinking tea at a Tomsk airport café, where Interfax news agency reported that the owners of the café were checking CCTV footage to see if any evidence could be provided.
By the afternoon, Navalny's wife, Yulia, had reached the hospital from Moscow. She brought with her Navalny's personal doctor, Anastasia Vasilyeva. The authorities, however, initially refused to allow them into the room. They demanded proof in the form of a marriage certificate that Yulia was indeed his wife. A chartered plane paid for by Cinema for Peace Foundation was sent from Germany to evacuate Navalny from Omsk for treatment at the Charité in Berlin. Approximately 31 hours after onset of his symptoms, a doctor from the German team was granted brief access to Alexey Navalny, and recorded bradycardia, hypothermia (34.4°C), and wide pupils non-reactive to light. According to German doctors, Navalny was under sedation with propofol, and it was the only obvious drug given at that time. The doctors treating him in Omsk had initially declared he was too sick to be transported but later released him, and he arrived in Berlin on 22 August. Alexander Murakhovsky, the head doctor at the Omsk hospital, told the press conference on 24 August that they had saved his life and found no traces of any poison in his system; he also said the doctors at the hospital had not been under pressure on the part of Russian officials. The doctors treating him at the Charité announced later in the day that while the specific substance was not yet known, clinical findings indicated poisoning with a substance from the group of nerve agents known as cholinesterase inhibitors, and that they would be performing further tests to discover the exact substance. Evidence might come with the publication of the initiated laboratory testing.
As of 2 September 2020, Navalny was in a medically-induced coma. German physicians said that if he recovered, lasting effects could not be ruled out. Dr. Murakhovsky wrote a letter to the Charité, demanding that they show laboratory data about him being poisoned with a cholinesterase inhibitor, stating the doctors in his hospital found no such evidence. He stated that cholinesterase decrease may have happened either by intake of a compound or naturally, also publishing a purported independent analysis detecting no cholinesterase inhibitors. He confirmed giving him atropine, which is used to counteract certain nerve agents and pesticide poisoning, but claimed the reasons were unrelated to poisoning.
On 7 September, doctors brought Navalny out of the medically-induced coma. In a press release, Charité said:
On 10 September, news media reported the police protection outside the Charité hospital had been stepped up, that Navalny was able to speak again, but Navalny's spokeswoman described reports of his quick recuperation as "exaggerated".
On 14 September, the Charité hospital said that Navalny was taken off the ventilator and that he is able to get out of bed. For the first time, the hospital said that it published the statement following consultations "with the patient and his wife", rather than his wife only.
On 15 September, Navalny's spokeswoman said that Navalny would return to Russia. Navalny also posted a picture from his hospital bed on social media for the first time since his poisoning. The Kremlin ruled out a meeting between Navalny and Putin.
On 22 September, the doctors at the Charité hospital declared him well enough to be discharged from in-patient care.
While recovering after discharge from the Charité hospital, Navalny stated "I assert that Putin was behind the crime, and I have no other explanation for what happened. Only three people can give orders to put into action 'active measures' and use Novichok ... [but] FSB director Alexander Bortnikov, foreign intelligence service head Sergey Naryshkin and the director of GRU cannot make such a decision without Putin's orders."
Investigation
Initial steps taken by Navalny's team members
Anti-Corruption Foundation (FBK) employees in Tomsk, having learned about the poisoning, told the administration of the hotel where Navalny had stayed that he could have been poisoned with "something from the minibar" and received permission to inspect his room. The inspection was carried out in the presence of a hotel administrator and a lawyer, and was filmed. Navalny's associates took his personal belongings from the room, including several plastic water bottles. The head of the FBK investigation department, Maria Pevchikh, subsequently took these bottles to Germany on the same medical plane on which Navalny himself was transported, and handed them over to German specialists. Although the Navalny's team member maintained control of the bottle, there is no official chain of custody for it.
On the same day, 20 August 2020, Navalny's lawyers appealed to the Investigative Committee of Russia and demanded for the initiation of a criminal case in accordance with the Articles 30, 105, and 227 of the Criminal Code of the Russian Federation.
Investigation by German authorities
Upon Navalny's admission to Charité hospital intensive care unit, toxicological analysis and drug screening in the patient's blood and urine samples was performed. Several drugs, including atropin were identified, whose presence was attributed to the previous treatment in Omsk. Cholinesterase status testing was performed in an external laboratory, and it showed virtually no activity of acetylcholinesterase in erythrocytes, which served as a strong evidence supporting exposure to cholinesterase inhibitor. Navalny's attending doctors from the Charité turned to Bundeswehr experts for help to check whether Navalny had been poisoned with a chemical warfare agent.
On 2 September 2020, the German government announced that scientists at the Bundeswehr Institute of Pharmacology and Toxicology obtained in unequivocal proof that Navalny was poisoned by Novichok type nerve agent. Although the German government did not disclose any technical details about the exact procedure of Novichok's identification, as well as a concrete formula of the poison, Marc-Michael Blum, an expert in chemical weapons testing and former OPCW employee suggested that the analytic procedure used by German chemists was similar to the one used for identification of Sarin poisoning, and it allows reliable identification of the poison at the parts per billion level. His opinion is in agreement with the opinion of Palmer Taylor, a pharmacologist at the University of California, San Diego.
Traces of the Novichok nerve agent were found in blood and urine, as well as on Navalny's skin samples. Traces of the poison were also found on one of Navalny's bottles, which had previously been handed over to Berlin doctors, and on some other undisclosed object(s). Experts suggest that Navalny drank from it after he was poisoned, and left traces on it. Navalny's team suggested that he was possibly poisoned before leaving the hotel. It was also stated that before leaving Russia, Navalny's clothes were seized by the Russian government.
Bruno Kahl, the head of Germany's foreign intelligence service, revealed that the Novichok agent identified from Navalny's toxicology results was a "harder" form than previously seen.
The research results from the Bundeswehr Institute of Pharmacology and Toxicology were handed over to the OPCW.
The Charité hospital, with Navalny's consent, published a scientific article titled "Novichok nerve agent poisoning" in the peer-reviewed medical journal The Lancet. In the article, 14 doctors described Navalny's clinical details and course of treatment. The doctors also confirmed that severe poisoning was the cause of Navalny's condition: "A laboratory of the German armed forces designated by the Organization for the Prohibition of Chemical Weapons identified an organophosphorus nerve agent from the Novichok group in blood samples collected immediately after the patient's admission to Charité." They also expressed the opinion that Navalny survived thanks to timely treatment and previous good health. After the publication, Navalny said that the evidence of the poisoning that Putin was demanding was now available to the whole world.
Technical assistance visit by the OPCW team
On 3 September 2020, the Organisation for the Prohibition of Chemical Weapons (OPCW) received from the German government a request of assistance according to the Chemical Weapons Convention. A team of inspectors visited the Charité Hospital, met Navalny, confirmed his identity, and directly supervised and monitored blood and urine sampling, which was conducted
by the hospital staff in line with the OPCW procedure. The samples, which were maintained under OPCW chain of custody, were transferred to two certified laboratories designated by the OPCW Director General.
Researchers in the two OPCW designated laboratories, the laboratory in Bouchet, subordinate to the Direction générale de l'armement and Umeå, subordinate to the Swedish Defence Research Agency, confirmed Navalny's poisoning with a Novichok nerve agent.
On 6 October 2020, the OPCW announced that results of testing samples obtained from Navalny had confirmed the presence of a Novichok nerve agent, saying:
The exact structure of the agent involved has not been publicly disclosed, but according to the announcement above, the compound shares structural similarities with A-232 (the example compound for schedule 1.A.14) and A-242 (the example compound for schedule 1.A.15). It was emphasized that any use of chemical weapons is "reprehensible and wholly contrary to the legal norms established by the international community." United Nations special rapporteur on Extrajudicial Executions Agnès Callamard and UN Special Rapporteur on the Promotion and Protection of the Right to Freedom of Opinion Irene Khan have confirmed that they intend to investigate Navalny's poisoning at his request.
Additional information available from semi-official or anonymous sources
According to Die Zeit and Der Spiegel, "a new and improved version of the Novichok agent, which has not been encountered in the world before", was used in Navalny's poisoning. This new type of Novichok is more toxic and dangerous than its previously known variants, but acts more slowly. It had been planned that Navalny would die on board the plane, but he had survived "thanks to a sequence of successful coincidences: the quick reaction of the pilot who made an emergency landing, and the doctors in Omsk, who immediately injected Navalny with atropine". German experts came to the conclusion that only Russian special services could have used such a "deadly and complex poison". To create a binary chemical weapon of this kind, a special laboratory is needed; it could not be synthesized by ordinary criminals. The German side rejected the version of Navalny's poisoning by foreign special services, as it would have been "unthinkable" in the conditions of constant surveillance of Navalny by the Russia's Federal Security Service (FSB): "All this allows us to draw only one plausible conclusion: it was the Kremlin who gave the order to get rid of unwanted criticism."
A source in the German special services told The New York Times that, according to German experts, Navalny was poisoned by Novichok in the form of a powder dissolved in a liquid, most likely in the tea he drank at the Russian airport. Given that the poison was also found on a bottle from Navalny's hotel room, The New York Times concluded that he could have been poisoned twice. Parliamentary Assembly of the Council of Europe has appointed Jacques Maire as special rapporteur on the poisoning of Navalny.
On 13 December 2020, an article from The Sunday Times, quoting anonymous intelligence sources, reported that Navalny had been poisoned a second time while in hospital in Omsk; the prior administration of the antidote atropine in response to the first poisoning is thought to have saved Navalny's life by counteracting the second dose of Novichok. Specialists found Novichok on the politician's underwear and clothes, including on his belt. The poison got on things after intelligence agents entered Navalny's hotel room in Tomsk.
Bellingcat and The Insider joint investigation
On 14 December 2020, Bellingcat and The Insider, in co-operation with CNN, Der Spiegel and Anti-Corruption Foundation, published a joint investigation implicating agents from Russia's Federal Security Service (FSB) in Navalny's poisoning. The investigation detailed a special unit of the FSB specialising in chemical substances, and the investigators tracked members of the unit using telecom and travel data. The same day, Navalny published a new video and tweeted: "Case closed. I know who tried to kill me. The case concerning my murder attempt is solved. We know the names, we know the job ranks, and we have the photos." According to the investigation, Navalny had been under surveillance by a group of eight operatives from the unit since 2017, and there may have been earlier attempts to poison him. The travel data of the alleged FSB officers were made publicly available. When asked about the investigation, Putin called it "the legalisation of the materials of American intelligence agencies" and confirmed that Russian security agents were tailing Navalny, claiming that Navalny was backed by U.S. intelligence and denying that he was poisoned.
In January 2021, Bellingcat in a separate joint investigation with Der Spiegel linked the unit that tracked Navalny and allegedly poisoned him to the deaths of two other activists including Timur Kuashev in 2014 and Ruslan Magomedragimov in 2015, as well as potentially the politician Nikita Isayev in 2019, but it noted that Isayev was "absolutely loyal" to the Kremlin and there was no motive for him to have been killed by the FSB.
According to Bellingcat, the same FSB unit had been involved in the assassination of Boris Nemtsov and the poisonings of Vladimir Kara-Murza and Dmitry Bykov.
Telephone conversation with an FSB agent
Following the investigation but before its publication, Navalny recorded his telephone conversation with Konstantin Borisovich Kudryavtsev, an FSB operative who was allegedly involved in his poisoning. The recording was released on 21 December 2020. During the phone conversation, Navalny posed as an aide to the secretary of Russia's Security Council Nikolai Patrushev, pretending to debrief Kudryavtsev about the operation and asking for details of why the mission had failed. Investigators used caller ID spoofing software to make the call look like it was coming from an FSB work phone number. Kudryavtsev unwittingly confessed that the Novichok agent had been applied to Navalny's underwear while he was staying at the hotel in Tomsk; but while Navalny had worn them for the flight as planned, the poison had apparently been absorbed too slowly. He attributed Navalny's survival to the pilots rerouting the flight and doctors in Omsk administering an antidote "almost immediately". Following Navalny's medical evacuation to Germany, the man said he had been sent to recover Navalny's clothes so that they could be treated to remove traces of Novichok before they could be tested by independent experts. The FSB later dismissed the recording of Navalny's telephone call as a forgery, calling it a "provocation" that "would not have been possible without the organizational and technical support of foreign special services". However, Bellingcat had arranged for its representatives to be present during the call, and they were; there are direct witnesses, in addition to the published audio and visual records of the call.
Russian state investigation
On 27 August 2020, Russian police and the Ministry of the Interior said they had launched a routine preliminary investigation into the poisoning, inspecting the hotel room and security footage. Russian police said that over 100 pieces of potential evidence had been collected. Prosecutors asserted that there was no need for any further investigation after the preliminary investigation, claiming it had found no sign that a crime had been committed.
Later developments
In January 2021, Navalny returned to Russia and was immediately detained on accusations of violating parole conditions while he was hospitalised in Germany. Following his arrest, mass protests were held across Russia. In February 2021, his suspended sentence was replaced with a prison sentence of over two and a half years' detention, and his organisations were later designated as extremist and liquidated. In March 2022, Navalny was sentenced to an additional nine years in prison after being found guilty of embezzlement and contempt of court in a new trial described as a sham by Amnesty International; his appeal was rejected and in June, he was transferred to a high-security prison. In August 2023, Navalny was sentenced to an additional 19 years in prison on extremism charges.
In December 2023, Navalny went missing from prison for almost three weeks. He re-emerged in an Arctic Circle corrective colony in the Yamalo-Nenets Autonomous Okrug. On 16 February 2024, the Russian prison service reported that Navalny had died at the age of 47.
Opinions of doctors and scientists
Opinions of scientists who participated in the development of Novichok
Vladimir Uglyov
One of the developers of substances like Novichok, Vladimir Uglyov, said that he "trusts the German specialists 100%" and suggested that the poison was delivered using "a solution (for example, in dimethylformamide) of a solid analogue of A-234, namely, a solid A-242, which was applied on Navalny's underwear, plus the addition of some faster-acting substance that hides symptoms (for example, clonidine)." Uglyov suggested that Novichok had been applied on Navalny's underwear in a hotel room, and that the poison had entered his body a few hours before departure. According to the scientist, Navalny received about 20% of the lethal dose. Uglyov suggested that the organizers decided to poison Navalny with Novichok, since they mistakenly believed that this substance would be impossible to detect. Uglyov also expressed the opinion that the Russian laboratory could not detect Novichok in the biological samples acquired from Navalny because "German specialists had more modern equipment and instruments for determining such quantities, which were taken from Alexei's blood. And those who did the tests in Moscow had much weaker equipment and the tests showed the absence of the substance." After the release of an independent investigation by Navalny, in which it was assumed that Alexei and his wife Yulia could have been subjected to attempts at poisoning earlier, Uglyov did not rule out that Navalny could have encountered Novichok three times, in previous cases receiving small doses insufficient for a lethal outcome.
Vil Mirzayanov
Chemical weapons specialist Vil Mirzayanov, who worked at GosNIIOKhT and in the 1990s revealed the Novichok development program in the USSR and Russia, agreed with the conclusions of the Bundeswehr special laboratory and suggested that the latest versions of Novichok were used to poison Navalny: the compounds A-242 or A-262. Mirzayanov also stated that the symptoms described by Navalny on 19 September were comparable to those he was aware of for similar cases.
Leonid Rink
One of the developers of the Novichok agent, Leonid Rink, stated that if Novichok had been used to poison Navalny, he "would have been dead, not left in coma" and suggested that what happened to Navalny was an attack of acute pancreatitis. This position was later dismissed as "nonsense" by doctor Yaroslav Ashikhmin who treated Navalny, as no increase in pancreatic enzymes was found in Navalny's blood. Another fact-checker pointed out at least three cases of people poisoned with Novichok who survived (Andrei Zheleznyakov, Sergei and Yulia Skripal) whose symptoms were very consistent with those of Navalny. Rink also theorized that Navalny had poisoned himself in a "big theater play" or that the Germans had copied Novichok and then poisoned Navalny in Germany, without providing any evidence for those theories. Rink had also previously (in 2018) echoed a theory floated in Russian state media that the British could have been behind the poisoning of Sergei Skripal. He had also in 1995 confessed to selling Novichok to a criminal gang for $1500 but was never convicted.
Opinions of other doctors and scientists
Reanimatologist (anesthesiologist) Boris Teplykh, one of the participants in the council of Russian doctors who treated Navalny in the first days after the poisoning, said in an interview with Meduza that the Russian specialists from the Moscow Medical Center of Forensic Medicine were looking for organophosphates and traces of cholinesterase inhibitors, but did not find any. Teplykh explained the difference in the test results of Russian and German specialists by the fact that "we worked with forensic toxicologists, and they [Germans] worked with superchemists who deal with chemical warfare agents. Slightly different things."
Navalny's attending physician Anastasia Vasilyeva stated on the TV channel RTVI that all Navalny's symptoms clearly indicated organophosphate poisoning. The fact that she, as the attending physician, was not allowed to examine Alexei, nor access consultations and medical documentation for two days, in her opinion, indicated that they had tried to hide the symptoms of poisoning from her, on the basis of which she concluded that the Omsk doctors were given instructions to be silent.
Andy Smith, Professor of the Department of Toxicology at the University of Leicester, noted that it would be difficult to identify a specific toxic substance in Navalny's body after a few days, though not impossible, given recent advances in analytical chemistry. He also noted that although Navalny, with the help of atropine and other drugs, had survived the acute stage of the poisoning, inhibition of cholinesterase could lead to the appearance of neurodegenerative and neuropsychiatric diseases. In his opinion, this was exactly what the poisoners were counting on.
The head of the Institute of Toxicology in Munich, Professor Martin Goettlicher, in an interview with Deutsche Welle, noted that Navalny's symptomatology was in many ways similar to that of the poisoning of Sergei and Yulia Skripal. For example, in both cases, patients were put into an artificial coma for about three weeks to restore cholinesterase. Goettlicher also explained that when Navalny was poisoned, those around him did not necessarily have to suffer, as was the case with the Skripals, since the Novichok can be an oily liquid that evaporates or spreads poorly, depending on how the substance got into the body and in what quantity.
German biochemist Dr. Marc-Michael Blum, who previously headed the OPCW laboratory, as well as the team investigating the poisoning of Sergei and Yulia Skripal, confirmed that when Navalny was poisoned by Novichok, those around him could not have suffered: according to Blum, this indicated either that the level of exposure to the substance or the degree of its ingress into Navalny's body was too low, or that no one around had come into contact with the epicenter of the poison. Blum praised the work of the laboratory of the Institute of Pharmacology and Toxicology of the Bundeswehr, which was the first to confirm the poisoning of Navalny by Novichok (Blum had worked there in 2006–2010). Blum categorically denied that the OPCW laboratories could have engaged in conspiracies and falsified the results of chemical analysis by anyone's political will. After the OPCW published its own report, Blum stated: "five laboratories ... certified by the OPCW ... did the same tests and came to the same result," that "Navalny was poisoned with a chemical agent." Blum confirmed that "use of chemical weapons" and "violation of the Chemical Weapons Convention" is not determined by the presence of a substance on the List of Schedule 1 substances (CWC): "in the end, there is no need for the substance to be on the list — the point is how it will be used."
Boris Zhuikov, Doctor of Chemistry and Head of the Laboratory of the Institute for Nuclear Research of the Russian Academy of Sciences, explained that although Novichok can break down in the body relatively quickly (for example, in a couple of days), when decomposed, it leaves behind specific compounds containing fragments of Novichok molecules, with which it is possible not only to confirm a poisoning by Novichok, but also to establish which substance from this group was used. The Russian team stated that it did not find Novichok itself in its analyses of Navalny's samples, while the German laboratory found traces of Novichok's presence. Zhuikov explained that these statements do not necessarily contradict each other: "the substance itself is really no longer there, but the interaction products remained." Modern methods of analysis (primarily mass spectrometry in combination with chromatography) make it possible to detect such chemical byproducts with very high sensitivity (for example, easily detecting the presence of 1 mg of poison in a human body weighing 70 kg), and the detection of these byproducts can unambiguously identify the original poisonous substance. The German laboratory of the Bundeswehr, which analyzed Navalny's samples, had such equipment.
A group of six leading Western experts in the field of toxicology and chemical weapons, in an interview with the BBC Russian Service, commented that prompt medical assistance saved Navalny's life: he was given the antidote atropine (perhaps preventively) and breathing support. Scientists explained that there were no other victims of Navalny's poisoning since only Navalny received a high dose of the poisonous substance and was in prolonged contact with it. Experts also said that it is impossible to find the components necessary for the manufacture of Novichok on the market (some components themselves fall under the ban under the Chemical Weapons Convention), and only military laboratories can produce such poisons, since this requires special equipment and special security conditions.
In November 2021, a statement was published by 55 states parties to the OPCW that condemned the use by a "toxic chemical as a weapon" against Navalny, confirmed presence of cholinease inhibitors consistent with the "Novichok" series and urged Russia to provide answers to OPCW questions, to which Russia has failed to do since 2020.
Reactions
The news of Navalny's poisoning caused the ruble to fall against the dollar and the euro.
On 20 August, UN spokesman Stéphane Dujarric expressed concern about Navalny's "sudden illness". U.S. President Donald Trump said the U.S. was monitoring reports on the leader of the Russian opposition. U.S. National Security Advisor Robert O'Brien said that reports of the possible poisoning of Navalny were causing "extreme concern" in Washington.
On 21 August, the Office of the United Nations High Commissioner for Human Rights said it expected Navalny to receive proper medical attention. The German government announced that there were serious grounds to suspect that poisoning had taken place, and called for Navalny to be provided with any medical assistance that could save him. Head of the European Council Charles Michel expressed concern about the state of Navalny. French President Emmanuel Macron stated that France was ready to offer "all necessary assistance ... in terms of health care, asylum, protection" to Navalny and his family and demanded clarity on the circumstances surrounding the incident. German Chancellor Angela Merkel also offered any medical assistance necessary in German hospitals. Amnesty International called for an investigation into the alleged poisoning. According to John Sipher, a former CIA station chief in Moscow, "Whether or not Putin personally ordered the poisoning, he is behind any and all efforts to maintain control through intimidation and murder".
On 24 August, German Chancellor Angela Merkel and Foreign Minister Heiko Maas in a joint statement called on the Russian authorities to clarify in detail and as transparently as possible the entirety of circumstances surrounding the incident, and to identify and prosecute those responsible. The head of EU diplomacy, Josep Borrell, said that the Russian authorities should immediately begin an independent and transparent investigation into the poisoning of Navalny.
On 25 August, French Foreign Minister Jean-Yves Le Drian said that France, on the basis of the preliminary conclusion of the Charité clinic doctors about Navalny's poisoning, considered the incident a criminal act and called for finding and punishing those responsible.
U.S. Deputy Secretary of State Stephen Biegun expressed deep concern about Navalny's condition, as well as the impact of reports of his poisoning on civil society in Russia. The American diplomat also stressed the importance of transparency and freedom of speech in any democratic state. Biegun said that "if Navalny's poisoning is confirmed, the U.S. could take steps that would exceed Washington's response to findings of Russian meddling in the 2016 U.S. presidential election."
On 25 August, businessman Yevgeny Prigozhin, who had ties to Putin and had been nicknamed "Putin's chef", was quoted as saying that he intended to enforce a court decision the previous year that required Navalny, his associate Lyubov Sobol and his Anti-Corruption Foundation to pay 88 million rubles in damages to the Moskovsky Shkolnik company over a video investigation. Prigozhin had bought the debt so that Navalny and his associate would owe him directly. Prigozhin was quoted by the company as saying "I intend to strip this group of unscrupulous people of their clothes and shoes" and that if Navalny survived, Navalny would be liable "according to the full severity of Russian law".
On 26 August, British Prime Minister Boris Johnson and NATO Secretary General Jens Stoltenberg joined in demanding a transparent investigation. According to Johnson, Navalny's poisoning "shocked the world," and Stoltenberg saw no reason to question the conclusions of the Charité doctors.
On 2 September, after the German government officially announced that the pharmaceutical and toxicology laboratory of the Bundeswehr found traces of poison from the Novichok group in Alexey Navalny's body, German Chancellor Angela Merkel issued a statement in which she called Navalny's poisoning an attempt to silence him: "Someone tried to silence [Mr Navalny] and in the name of the whole German government I condemn that in the strongest terms." Merkel said that "Mr. Navalny ha[d] been the victim of a crime" which "raise[d] very serious questions that only the Russian government c[ould] and must answer". The European External Action Service in a statement condemned the poisoning and said that it is "essential that the Russian government investigates thoroughly and in a transparent manner the assassination attempt of Mr Navalny". Boris Johnson demanded that Russia provide an explanation and said that he considered it "outrageous that a chemical weapon was used against Alexey Navalny." He promised to "work with international partners to ensure justice is done." Jean-Yves Le Drian condemned the "shocking and irresponsible" use of a Novichok poisoning agent and said it was in violation of the ban on the use of chemical weapons. The Italian Foreign Ministry "condemned with force" the poisoning of Navalny, called this act a "crime", and, expressing "profound concern and indignation", demanded an explanation from Russia.
Stephen Biegun stated that the U.S. finds the German conclusion about the use of Novichok "very credible" and "deeply concerning". Navalny's chief of staff, Leonid Volkov, stated "In 2020, poisoning Navalny with Novichok is the same as leaving an autograph at the scene of the crime".
On 3 September, the European Council called the incident an "assassination attempt". After the German government concluded that Navalny was poisoned by Novichok, the wife of British policeman Nick Bailey, who was exposed to Novichok after the poisoning of Sergei and Yulia Skripal, tweeted, "It's been almost years after the events in Salisbury and there has been no justice for Dawn and her family and none for the Skripals, Charlie or us. And now it's happened again".
On 4 September, Jens Stoltenberg stated: "Time and again, we have seen opposition leaders and critics of the Russian regime attacked, and their lives threatened. Some have even been killed. So this is not just an attack on an individual, but on fundamental democratic rights. It is a serious breach of international law, which demands an international response." He also asked the Russian authorities to fully cooperate with an impartial international investigation.
On 5 September, Donald Trump announced that the United States should soon receive documents from Germany on the Navalny case, which will allow Washington to determine its position. He noted that he had no reason to question Germany's conclusions that Navalny was poisoned by Novichok, and stressed that if the fact of the poisoning was confirmed, it would anger him.
On 6 September, Heiko Maas said that Germany was planning to discuss possible sanctions against Russia if the Kremlin does not provide an explanation soon, saying that any sanctions should be "targeted". Maas also said that there were "several indications" that Russian authorities were behind the poisoning. He also said that a lack of support from Russia in the investigation could "force" Germany to change its position on the Nord Stream 2 gas pipeline from Russia to Germany.
On 8 September, UN High Commissioner for Human Rights Michelle Bachelet called on Russia "to carry out, or fully cooperate with, a thorough, transparent, independent and impartial investigation, after German specialists said they have "unequivocal proof" that he was poisoned with a Novichok nerve agent."
In a March 2021 report, the East StratCom Task Force of the European External Action Service registered an increase in false information propagated in Russia about Germany as a result of the deterioration in German-Russian relations developed since the poison attack. In 2020 The Task Force reported over 300 cases of false information targeting Alexei Navalny, while most of the cases have appeared after the poisoning.
Comments by political scientists and sociologists
Political scientist Nikolai Petrov, senior fellow at the Royal Institute of International Affairs (Chatham House) and professor of political science at the Higher School of Economics, commenting on the poisoning of Navalny for The New York Times, noted that in the Kremlin "no one else causes such hostility and fear as Navalny". This means that "there is a very long list of potential enemies" who may wish for Navalny's death, or at least want to render him incapacitated. However, Navalny is such a prominent figure in Russia that none of his personal enemies would have dared to take such radical measures against him without, "at least, the tacit consent of Putin." According to Petrov, in Russia there is a system "like in the mafia: nothing can be done without the approval and guarantees of immunity from the boss. I'm not saying that Putin directly ordered the poisoning of him, but no one can act without making sure the boss is happy and punishes them."
The opinion that Putin personally was involved in the poisoning of Navalny was also expressed by the doctor of historical sciences, political scientist Valery Solovei. In his opinion, such operations cannot be carried out without Putin knowing about them, who at least was aware of the poisoning plans. Solovei also believes that after returning to Russia, they will continue to exert financial pressure on Navalny and will try to "hit all his connections, all with whom he cooperates and interacts."
Mark Galeotti, an expert on Russian special services and professor emeritus at University College London, noted in an interview with Deutsche Welle that the use of Novichok is proof that either the state or "someone with a high degree of power and authority in the state" was involved in the attempt to poison Navalny. According to Galeotti, if the measures taken by the West in response to this poisoning are not effective, then Moscow will continue to carry out such operations.
Former German ambassador to Russia and former vice-president of the Federal Intelligence Service of Germany Rüdiger von Fritsch, commenting on the inaction of the Russian Federation in the investigation of Navalny's poisoning, said: "For more than three weeks now we have been in a situation where Russia does not help in any way in the investigation, but only puts forward accusations in reply ... The one who stole himself then shouts very loudly, pointing in the other direction. We are faced with this for the umpteenth time. The scenario is the same: reprimands, shifting the burden of gathering evidence to others, threats, ridicule. The most important thing is not to conduct an investigation, never".
Professor of Rutgers University, sociologist Sergei Erofeev said that a group of professors from a number of recognized universities nominated Navalny for the Nobel Peace Prize as having made a significant contribution to the fight for human rights. Erofeev noted that although the very idea of such a nomination is not new, it acquired particular relevance in connection with the poisoning of Navalny.
Retired FSB General said that the poisoning of Navalny is "an act of state terrorism", in which "the president and his special services" were involved.
Researcher of the Russian armed forces and special services Mark Galeotti, commenting on the telephone conversation between Navalny and the FSB agent, said that Navalny was able to "demonstrate how much top-secret information is available on the darknet — phone numbers, names, everything else. And that all this can be used to identify individuals. And what's more, getting them to talk about their work."
Polls
According to polls conducted by the Levada Center in December 2020, 78% of Russian respondents had heard about Navalny's poisoning. 30% of the respondents believed there was no poisoning at all and that it is a mock-up, 19% opted for a provocation of Western special services, 15% opted for an attempt by the authorities to eliminate the political opponent. 7% of respondents see a personal revenge on one of the people involved in Navalny's investigations, 6% a struggle within the Russian opposition, and 1% believe in health problems, accidental poisoning, or common poisoning. 4% think other reasons are more likely, and 19% find the question hard to answer. There was a significant correlation between the belief in poisoning by the authorities and age, sources of information, and attitude towards the government in general.
Film
Navalny, a 2022 documentary directed by Daniel Roher was released recounting the days leading up to, during, and after the assassination attempt.
On the review aggregator website Rotten Tomatoes, 99% of 97 critics' reviews are positive, with an average rating of 8.4/10. The website's consensus reads, "Navalny is a documentary that's as gripping as any thriller – but the real-life fight against authoritarianism that it details is deadly serious." Metacritic, which uses a weighted average, assigned the film a score of 82 out of 100, based on 22 critics, indicating "universal acclaim".
The Guardian critic Phil Harrison awarded it 5/5 stars calling it "... one of the most jaw-dropping things you'll ever witness", and "this terrifying documentary enters the realms of the far-fetched spy thriller – and yet it's all true". New York Times film critic Ben Kenigsberg added the film to the "Critic's List" and also praised it saying "Roher has assembled a tense and absorbing look at Navalny and his inner circle".
See also
Pyotr Verzilov
Assassination of Anna Politkovskaya
Assassination of Boris Nemtsov
Poisoning of Alexander Litvinenko
Poisoning of Sergei and Yulia Skripal
Vladimir Vladimirovich Kara-Murza
Viktor Yushchenko
Death of Alexei Navalny
References
Chemical weapons attacks
Novichok agents
Navalny
2020 in international relations
Alexei Navalny
Navalny, Alexei
August 2020 events in Russia
Tomsk
History of Omsk
Charité
August 2020 crimes in Europe
Violence in Russia
History of Tomsk Oblast | Poisoning of Alexei Navalny | [
"Chemistry",
"Environmental_science"
] | 9,723 | [
"Toxicology",
"Chemical weapons",
" medicaments and biological substances",
"Chemical weapons attacks",
"Poisoning by drugs"
] |
65,073,375 | https://en.wikipedia.org/wiki/Zero%20trust%20architecture | Zero trust architecture (ZTA) or perimeterless security is a design and implementation strategy of IT systems. The principle is that users and devices should not be trusted by default, even if they are connected to a privileged network such as a corporate LAN and even if they were previously verified.
ZTA is implemented by establishing identity verification, validating device compliance prior to granting access, and ensuring least privilege access to only explicitly-authorized resources. Most modern corporate networks consist of many interconnected zones, cloud services and infrastructure, connections to remote and mobile environments, and connections to non-conventional IT, such as IoT devices.
The traditional approach by trusting users and devices within a notional "corporate perimeter" or via a VPN connection is commonly not sufficient in the complex environment of a corporate network. The zero trust approach advocates mutual authentication, including checking the identity and integrity of users and devices without respect to location, and providing access to applications and services based on the confidence of user and device identity and device status in combination with user authentication. The zero trust architecture has been proposed for use in specific areas such as supply chains.
The principles of zero trust can be applied to data access, and to the management of data. This brings about zero trust data security where every request to access the data needs to be authenticated dynamically and ensure least privileged access to resources. In order to determine if access can be granted, policies can be applied based on the attributes of the data, who the user is, and the type of environment using Attribute-Based Access Control (ABAC). This zero-trust data security approach can protect access to the data.
History
In April 1994, the term "zero trust" was coined by Stephen Paul Marsh in his doctoral thesis on computer security at the University of Stirling. Marsh's work studied trust as something finite that can be described mathematically, asserting that the concept of trust transcends human factors such as morality, ethics, lawfulness, justice, and judgement.
The problems of the Smartie or M&M model of the network (the precursor description of de-perimeterisation) was described by a Sun Microsystems engineer in a Network World article in May 1994, who described firewalls' perimeter defence, as a hard shell around a soft centre, like a Cadbury Egg.
In 2001 the first version of the OSSTMM (Open Source Security Testing Methodology Manual) was released and this had some focus on trust. Version 3 which came out around 2007 has a whole chapter on Trust which says "Trust is a Vulnerability" and talks about how to apply the OSSTMM 10 controls based on Trust levels.
In 2003 the challenges of defining the perimeter to an organisation's IT systems was highlighted by the Jericho Forum of this year, discussing the trend of what was then given the name "de-perimeterisation".
In response to Operation Aurora, a Chinese APT attack throughout 2009, Google started to implement a zero-trust architecture referred to as BeyondCorp.
In 2010 the term zero trust model was used by analyst John Kindervag of Forrester Research to denote stricter cybersecurity programs and access control within corporations. However, it would take almost a decade for zero trust architectures to become prevalent, driven in part by increased adoption of mobile and cloud services.
In 2018, work undertaken in the United States by cybersecurity researchers at NIST and NCCoE led to the publication of NIST SP 800-207 – Zero Trust Architecture. The publication defines zero trust (ZT) as a collection of concepts and ideas designed to reduce the uncertainty in enforcing accurate, per-request access decisions in information systems and services in the face of a network viewed as compromised. A zero trust architecture (ZTA) is an enterprise's cyber security plan that utilizes zero trust concepts and encompasses component relationships, workflow planning, and access policies. Therefore, a zero trust enterprise is the network infrastructure (physical and virtual) and operational policies that are in place for an enterprise as a product of a zero trust architecture plan.
There are several ways to implement all the tenets of ZT; a full ZTA solution will include elements of all three:
Using enhanced identity governance and policy-based access controls.
Using micro-segmentation
Using overlay networks or software-defined perimeters
In 2019 the United Kingdom National Cyber Security Centre (NCSC) recommended that network architects consider a zero trust approach for new IT deployments, particularly where significant use of cloud services is planned. An alternative but consistent approach is taken by NCSC, in identifying the key principles behind zero trust architectures:
Single strong source of user identity
User authentication
Machine authentication
Additional context, such as policy compliance and device health
Authorization policies to access an application
Access control policies within an application
See also
Blast radius
Password fatigue
Secure access service edge
Identity threat detection and response
References
Information technology
Computer network security
Computer security models | Zero trust architecture | [
"Technology",
"Engineering"
] | 986 | [
"Information and communications technology",
"Cybersecurity engineering",
"Computer networks engineering",
"Information technology",
"Computer network security"
] |
65,074,381 | https://en.wikipedia.org/wiki/Elliptical%20dome | An elliptical dome, or an oval dome, is a dome whose bottom cross-section takes the form of an ellipse. Technically, an ellipsoidal dome has a circular cross-section, so is not quite the same.
While the cupola can take different geometries, when the ceiling's cross-section takes the form of an ellipse, and due to the reflecting properties of an ellipse, any two persons standing at a focus of the floor's ellipse can have one whisper, and the other hears; this is a whispering gallery.
The largest elliptical dome in the world is at the Sanctuary of Vicoforte in Vicoforte, Italy.
In architecture
Elliptical domes have many applications in architecture; and are useful in covering rectangular spaces. The oblate, or horizontal elliptical dome is useful when there is a need to limit height of the space that would result from a spherical dome. As the mathematical description of an elliptical dome is more complex than that of spherical dome, design care is needed.
In a geodesic dome with a circular base, the triangular elements align so their edges form great circles. Although not geodesic, a new, elliptical design was patented in 1989; it uses hexagons and pentagons to form a dome with a cross section that is elliptical. Due to its mathematical derivation, this design is called "geotangent".
World examples
Elliptical domes come up in the design of all of the following:
A number of mosques in Cairo, Egypt,
Part of St. Peter's Basilica, in Rome, Italy
The Basilica of St. Lawrence, Asheville, in Asheville, North Carolina,
The Church of Saint Roch, Žižkov, in Prague, Czech Republic,
The Four Domes Pavilion, in Wroclaw, Poland,
The Indiana Theatre, in Indiana, city of Indianapolis,
The Joe and Rika Mansueto Library, at the University of Chicago,
The Kanteerava Indoor Stadium, in Bangalore, India,
The Mayflower Hotel, in Washington, DC,
The Mosque–Cathedral of Córdoba, in Andalusia,
The Palau Nacional, in Barcelona, Spain,
The Pisa Cathedral, in Pisa, Italy,
The Rose Hill Mansion, Bluffton, in Bluffton, South Carolina,
The San Filippo Neri, in Turin, region of Piedmont, Italy,
The Sant'Andrea in Via Flaminia, in Rome, Italy,
The Santa Caterina, Casale Monferrato, in Casale Monferrato, Province of Alessandria, region of Piedmont, Italy,
The Seville Cathedral, Spain,
The Skyspace Lech, Tannegg/Oberlech in Vorarlberg, the westernmost federal state of Austria,
The State Savings Bank Building, in City of Sydney, Australia,
The Temple Sinai, in Oakland, California,
The Sanctuary of Vicoforte, in Italy,
BAPS Swaminarayan Akshardham (New Jersey), in Robbinsville, New Jersey.
See also
Pendentive
Beehive house
Beehive tomb
Catenary arch
Clochán
Ellipsoid
Onion dome
Parabolic arch
References
External links and references
Creating elliptical domes
Elliptical domes site
Creating an elliptical dome
Another reference, on creating ellitpical domes
Calculations
Site for calculating figures related to elliptical domes
Another site for calculations
Dome calculator
More general references
Buckling of Externally Pressurized Prolate Ellipsoidal Domes
An article addressing many topics, including elliptical domes
Use of elliptical domes, notably in Islamic architecture
Domes
Architectural elements | Elliptical dome | [
"Technology",
"Engineering"
] | 723 | [
"Building engineering",
"Architectural elements",
"Components",
"Architecture"
] |
65,074,394 | https://en.wikipedia.org/wiki/LEAPER%20gene%20editing | LEAPER (Leveraging endogenous ADAR for programmable editing of RNA) is a genetic engineering technique in molecular biology by which RNA can be edited. The technique relies on engineered strands of RNA to recruit native ADAR enzymes to swap out different compounds in RNA. Developed by researchers at Peking University in 2019, the technique, some have claimed, is more efficient than the CRISPR gene editing technique. Initial studies have claimed that editing efficiencies of up to 80%.
Synopsis
As opposed to DNA gene editing techniques (e.g., using CRISPR-Cas proteins to make modifications directly to a defective gene), LEAPER targets editing messenger RNA (mRNA) for the same gene which is transcribed into a protein. Post-transcriptional RNA modification typically involves the strategy of converting adenosine-to-inosine (A-to-I) since inosine (I) demonstrably mimics guanosine (G) during translation into a protein. A-to-I editing is catalyzed by adenosine deaminase acting on RNA (ADAR) enzymes, whose substrates are double-stranded RNAs. Three human ADAR genes have been identified with ADAR1 (official symbol ADAR) and ADAR2 (ADARB1) proteins developed activity profiles. LEAPER achieves this targeted RNA editing through the use of short engineered ADAR-recruiting RNAs (). consist of endogenous ADAR1 proteins with several RNA binding domains (RBDs) fused with a peptide, CRISPR-Cas13b protein, and a guide RNA (gRNA) between 100 and 150 nt in length for high editing efficiency designed to recruit the chimeric ADAR protein to a target site.
This results in a change in which protein is synthesized during translation.
History
The technique was discovered by a team of researchers at Peking University in Beijing, China. The discovery was announced in the journal Nature Biotechnology in July 2019.
Applications
Chinese researchers have utilized LEAPER to restore functional enzyme activity in cells from patients with Hurler syndrome. They have claimed that LEAPER could have the potential to treat almost half of all known hereditary disorders.
Highly specific editing efficiencies of up to 80% can be achieved when LEAPER editing using arRNA151 is delivered via a plasmid or viral vector or as a synthetic oligonucleotide, though this efficiency varied significantly across cell types. Based on these preliminary results, LEAPER may have the most therapeutic promise with no production of functional protein but if a partial restoration of protein expression would provide therapeutic benefit. For example, in human cells with defective α-L-iduronidase (IDUA) expression in cells from patients with IDUA-defective Hurler syndrome, LEAPER resulted in a W53X truncation mutant of p53 being edited using arRNA151 to achieve a "normal" p53 translation and functional p53-mediated transcriptional responses.
Comparison to CRISPR
LEAPER is analogous to CRISPR Cas-13 in that it targets RNA before proteins are synthesized. However, LEAPER is simpler and more efficient as it only requires , rather than Cas and a guide RNA. According to the developers of LEAPER, it has the potential to be easier and more precise than any CRISPR technique.
LEAPER also eliminates health concerns and technical barriers arising from the introduction of exogenous proteins.
It has also been called more ethical as it does not change DNA and thus does not result in heritable changes, unlike methods using CRISPR Cas-9.
See also
CRISPR gene editing
Gene knockout
NgAgo
Prime editing
References
Genetic engineering
Genome editing
Biotechnology
RNA
Biochemistry | LEAPER gene editing | [
"Chemistry",
"Engineering",
"Biology"
] | 749 | [
"Genetics techniques",
"Biological engineering",
"Genome editing",
"Genetic engineering",
"Biotechnology",
"nan",
"Molecular biology",
"Biochemistry"
] |
65,074,511 | https://en.wikipedia.org/wiki/Zakya%20Kafafi | Zakya H. Ismail (born 1948) is an Egyptian scientist who is professor of Electrical Engineering at Lehigh University. Her research considers printed electronics and photonics. She was the first woman to be appointed to the National Science Foundation Director of the Division of Materials Research.
Early life and education
Kafafi was born in Cairo, Egypt. She has said that she became interested in chemistry whilst she was at high school, and that her science teacher frequently referred to her as The Chemist. She started her undergraduate degree in chemistry at the University of Houston, where she minored in mathematics. She moved to Rice University for her graduate studies and gained her MA and PhD in chemistry, and worked on low-temperature spectroscopy. At Rice University Kafafi was friends with Marilyn E. Jacox. After completing her doctorate, Kafafi moved to Cairo, where she was appointed Assistant Professor.
Research and career
In 1986, while on a sabbatical, Kafafi visited the United States, where she learned about a job that was open in the Optical Sciences Division at the United States Naval Research Laboratory (NRL). Kafafi eventually joined NRL, where she established the organic optoelectronics section. Here she worked on nonlinear optical materials and colour centre lasers. She transitioned from chemistry to materials science and eventually ended up in physics, studying the properties of OLEDs. Kafafi spent over twenty years working at the NRL, during which time OLED displays found their way into televisions and mobile phones.
In 2007 Kafafi was appointed to the National Science Foundation Director of the Division of Materials Research, during which time she oversaw a billion dollar budget. She was the first woman to hold such a position. In 2010 Kafafi returned to Egypt, where she looked to develop partnerships that promoted solar energy across the country.
Kafafi joined the faculty at Lehigh University in 2008, where she was made Distinguished Research Fellow in the Department of Electrical Engineering. Here she has developed metallic plasmonic nanostructures that can increase light absorption and the efficiency of photovoltaics. These nanostructures make it possible to increase the optical absorption of the active layer of photovoltaics without increasing the layer thickness, allowing for improved device performance without compromising the flexibility or weight.
From 2011 to 2016 Kafafi served as Editor-in-Chief of the Journal of Photonics for Energy. In 2014 Kafafi became the inaugural editor of the journal Science Advances.
Awards and honours
2004 NRL Edison Patent Award
2005 Elected Fellow of the American Association for the Advancement of Science
2007 Elected Fellow of The Optical Society
2007 Elected Fellow of the American Association for the Advancement of Science
2015 Elected Fellow of the Materials Research Society
2017 American Chemical Society Hillebrand Prize
2018 Kuwait Foundation for the Advancement of Sciences Kuwait Prize in Applied Sciences
2021 Elected Member of the National Academy of Engineering
Select publications
References
1948 births
Living people
Egyptian scientists
Rice University alumni
University of Houston alumni
Fellows of the American Association for the Advancement of Science
Fellows of Optica (society)
Fellows of SPIE
Members of the United States National Academy of Engineering
Women materials scientists and engineers
Women in optics
Egyptian women scientists | Zakya Kafafi | [
"Materials_science",
"Technology"
] | 639 | [
"Women materials scientists and engineers",
"Materials scientists and engineers",
"Women in science and technology"
] |
65,077,073 | https://en.wikipedia.org/wiki/Qatar-2 | Qatar-2 is a K-type main-sequence star about 595 light-years away in the constellation of Virgo. The star is much older than Sun, and has a concentration of heavy elements similar to solar abundance. The star features a numerous and long-lived starspots, and belongs to a peculiar variety of inflated K-dwarfs with strong magnetic activity inhibiting internal convection.
Planetary system
In 2011 a transiting superjovian planet Qatar-2b was detected by the Qatar Exoplanet Survey. The planet has a large measured temperature difference between dayside (1368 K) and nightside (724 K). The planetary orbit is well aligned with the equatorial plane of the star, misalignment angle equal to 4.3◦. No orbital decay was detected. The color of planetary atmosphere is blue due to Rayleigh scattering of light, and albedo is very low, being below 0.06.
An additional massive companion on wide orbit was suspected in 2011, but search utilizing transit-timing variation method has yielded zero results in 2017.
References
Virgo (constellation)
K-type main-sequence stars
Planetary systems with one confirmed planet
Planetary transit variables
J13503740-0648145 | Qatar-2 | [
"Astronomy"
] | 250 | [
"Virgo (constellation)",
"Constellations"
] |
65,077,141 | https://en.wikipedia.org/wiki/CYP107G1 | Cytochrome P450 family 107 subfamily G member 1 (abbreviated CYP107G1) is an actinobacterial Cytochrome P450 enzyme originally from Streptomyces rapamycinicus, which catalyzes the oxidation reaction of C27 of pre-rapamycin in the biosynthesis pathway of the macrolide antibiotic rapamycin.
References
Cytochrome P450
EC 1.14.15
Prokaryote genes | CYP107G1 | [
"Biology"
] | 100 | [
"Prokaryotes",
"Prokaryote genes"
] |
65,078,222 | https://en.wikipedia.org/wiki/Koonibba%20Test%20Range | The Koonibba Test Range is a rocket test range site near the township of Koonibba in the far west of South Australia. Rockets are launched to the north over a clear area – the Yumbarra Conservation Park and Yellabinna Wilderness Protection Area – for .
Koonibba Test Range was reported in 2020 to be the world's largest privately owned rocket test range and the world's first permitted by an indigenous community to be launched from their land. The range allows companies, universities, space agencies and other organisations to pay for their rockets to be taken to the site, launched, and rockets and payloads to be recovered.
History
In 2019 and 2020, the private space company Southern Launch consulted with the Koonibba Community Aboriginal Corporation, an Aboriginal corporation, before developing the test range site. Members of the local community have been employed to set up and operate the range.
DEWC Systems, an Adelaide-based company, conducted two launches at the range in September 2020. A rocket containing a small replica payload was scheduled to be launched on 15 September 2020, with a second launch on 19 September. The first launch failed, but both launches were successful on the morning of 19 September 2020. It was aimed at collecting information to develop a new technology consisting of tiny cube-shaped satellites, known as cubesats, for electronic warfare. The training and employment opportunities were welcomed by the community.
In October 2023 it was reported that Varda Space Industries had reached an agreement with Southern Launch to reenter and land their second mission at the Koonibba Test Range, due to launch mid-2024.
On 3 May 2024, HyImpulse's SR75 suborbital rocket flew its maiden launch (mission titled "Light this Candle"; expected apogee: ) successfully from Koonibba. The German-made hybrid-propellant rocket was fueled by candle wax, and was the biggest spacecraft launched on Australian soil.
Description
Koonibba Test Range covers , making it the largest launch pad in the Southern Hemisphere. It is situated in an uninhabited conservation park about north-west of Ceduna, and intended for use launching and recovering rockets and for space research. The advantage of the site is that the land on which the rockets may be recovered is vast.
Community impact and response
Most of the 125 residents of Koonibba, who had been involved in negotiations with the launch company over the six years prior, supported the launch. In May 2024 it was reported that the facility was delivering educational benefits for local schools; a group of Koonibba Aboriginal School students, assisted by Southern Launch engineers and technicians, had developed rockets, later presenting their work at a STEM conference in Adelaide, and intended to continue to do so. Koonibba Aboriginal Community Council reported that jobs in training and traffic management had been created. there were plans to build a space observatory to attract tourists.
Some local people are concerned about the impact of the rockets on sacred women's sites, and the next generation's connection to country. Sue Coleman-Haseldine, a Kokatha elder, has protested with a small group. Her concerns relate to the possible contribution by the launch pad to the development of weapons technology. She was born at Koonibba Mission in the generation that was affected by the British nuclear tests at Maralinga and Emu Field in the 1950s, and is one of the custodians of the land, with a duty to protect the land, animals, and stories, such as the Seven Sisters songline, a creation story in Aboriginal Australian mythology.
References
Rocket launch sites in Australia
Eyre Peninsula | Koonibba Test Range | [
"Astronomy"
] | 733 | [
"Rocketry stubs",
"Astronomy stubs"
] |
65,083,449 | https://en.wikipedia.org/wiki/Francis%20Allard | Francis Allard is a French academic, engineer and Distinguished Professor in Civil Engineering. Since February 2017, Allard is professor emeritus at La Rochelle University and Chairman of Tipee (Building Innovation Platform)> He has expertise in heat and mass transfer phenomena with application in energy efficiency and indoor environment in buildings and urban microclimate.
Publications
Books
Allard, Francis. Natural ventilation in buildings. A design handbook. (1998). (Cited 796 times, according to Google Scholar )
Allard F, Ghiaus C, editors. Natural ventilation in the urban environment: assessment and design. Routledge; 2012 Jun 25.(Cited 165 times, according to Google Scholar.)
Journal articles
Blondeau P, Iordache V, Poupard O, Genin D, Allard F. Relationship between outdoor and indoor air quality in eight French schools. Indoor air. 2005 Feb 1;15(1):2-12.7)
Blondeau P, Spérandio M, Allard F. Night ventilation for building cooling in summer. Solar energy. 1997 Nov 1;61(5):327-35.)
Kurnitski J, Allard F, Braham D, Goeders G, Heiselberg P, Jagemar L, Kosonen R, Lebrun J, Mazzarella L, Railio J, Seppänen O. How to define nearly net zero energy buildings nZEB. Rehva Journal. 2011 May;48(3):6-12.)
Ghiaus C, Allard F, Santamouris M, Georgakis C, Nicol F. Urban environment influence on natural ventilation potential. Building and environment. 2006 Apr 1;41(4):395-406.)
References
Year of birth missing (living people)
Living people
Place of birth missing (living people)
French academics
French civil engineers | Francis Allard | [
"Engineering"
] | 384 | [
"Civil engineering",
"Civil engineering stubs"
] |
65,083,835 | https://en.wikipedia.org/wiki/Gilda%20H.%20Loew | Gilda H. Loew (1930–January 5, 2001) was an American chemist known for applying computational chemistry to biology. She was elected a Fellow of the American Physical Society in 1975.
Career
A native of Brooklyn, New York, Loew attended Erasmus Hall High School and then went on to earn a bachelor's degree from New York University and a master's from Columbia, both in chemistry, before going on to doctoral work at UC Berkeley, where she earned a PhD in chemical physics. In the 1950s and 1960s, she held a number of research positions, at the Lawrence Radiation Laboratory, the Lockheed Missiles and Space Company and the Hansen Laboratories, Stanford University. According to Harel Weinstein and Hugo O. Villar, she became "a pioneer in the application of computational chemistry to problems in the biological sciences". After several years as an associate professor of physics at Pomona College, Loew was appointed as an adjunct professor in the department of genetics at Stanford in 1969, holding this position until 1979, when she established the Molecular Research Institute in Palo Alto, which she led for two decades. She was also an adjunct professor at Rockefeller University between 1978 and 1990.
The research of Loew's that remained critical to those that followed her was the cytochrome P450 protein family and her thirty years of investigation into their characteristics and properties, along with their three dimensional structure and how they interfaced with enzymatic substrates. In doing this research, Loew pioneered using new forms of technology that became available over the years, including numerous advances in computer modeling of proteins. Loew, related to said research, wrote a chapter on the properties of iron porphyrins for the first volume of the textbook series Physical Bioinorganic Chemistry in 1983.
Legacy
The International Society of Quantum Biology and Pharmacology (ISQBP) established the ISQBP Loew Lectureship in her memory in 2004, along with the Gilda Loew Memorial Award after donations were set up by her husband. The following year, the Gilda Loew Memorial Meeting was organized where over 20 speakers presented on topics that were of interest to Loew and her past research.
Personal life
Loew was married to Gregory Loew and had five children and three grandchildren at the time of her death from breast cancer at 70 years old on January 5, 2001.
References
Further reading
American women chemists
University of California, Berkeley alumni
Stanford University faculty
1930 births
2001 deaths
20th-century American women scientists
20th-century American chemists
Columbia Graduate School of Arts and Sciences alumni
Columbia University alumni
Scientists from Brooklyn
American physical chemists
Women physical chemists
Fellows of the American Physical Society
Pomona College faculty
Rockefeller University faculty
Deaths from breast cancer in California | Gilda H. Loew | [
"Chemistry"
] | 552 | [
"Women physical chemists",
"Physical chemists"
] |
65,084,570 | https://en.wikipedia.org/wiki/Austrian%20Resin%20Extraction | "Pecherei" is the common expression in southern Lower Austria for the practice of Resin Extraction from black pine trees (Evergreens). This profession centers around the extraction of tree resin, also known as "Pitch," that will ultimately be used in the production of further chemical products. Those who extract resin for a living are described as "Pecher" or "Resin Workers." In the year 2011, Pecherei was incorporated into the register of Intangible Cultural Heritage in Austria, which was drafted in the context of the UNESCO Convention for the Preservation of Intangible Culture.
The most important tree for use in resin extraction is the black pine (Pinus nigra), which has the greatest resin content of all of the European coniferous trees, and it was even used as early as by the Romans for this very purpose. These trees are generally best tapped for their resin between the ages of 90 and 120 years old. In Lower Austria, the Austrian Black Pine is the predominant tree, and its resin is of particularly high-quality, thereby making the Austrian pitch one of the best in the world.
History
In the southern part of Lower Austria, most prominently in the Industrial Quarter and the Vienna Woods, Pecherei became an established practice probably as early as the 17th century. From the beginning of the 18th century, lords of local manors began to promote pitch extraction, which led to the emergence of Pitch Huts for resin processing. In fact, at this time, Pecherei and the trading business surrounding it became an important source of income for some members of the population.
In the early decades of the 19th century, resin extraction experienced its first heyday, as an increase in demand led to increasing prices and production. However, throughout the 1960s, the industry gradually came to a standstill. The main reason for this was the fact that cheaper, comparable products were being imported from eastern-bloc countries (communist countries during the cold war) as well as from Turkey, Greece, and Portugal. Also, around this time there were numerous advances in technical chemistry that made resin less necessary for numerous products.
Austrian Social Security Law still recognizes the Pecherei profession in the context of independent practitioners. This profession is defined as follows:
"Self-employed Resin Workers are people who, without being employed on the basis of a service or apprenticeship relationship, pursue a seasonally recurring, monetarily gainful activity by extracting resin products in forests outside their home area, provided that they usually pursue this gainful activity without the help of non-family workers."
Raw Materials and Processing
The raw resin is light yellow in color. It is rich in organic hydrocarbons, but it has a low oxygen content and is nitrogen-free. Additionally, raw resin is largely a mix of terpene-derived substances, with many having acidic properties. The resin owes its spicy, aromatic smell to the abundant essential oils it contains.
The resin flow within a tree differs based on the time of year and the weather, with warmth and humidity having beneficial effects. Between 3 and 4 kilograms of Pitch could be obtained from a single trunk in one year. So, in order for a Resin Worker to live modestly with his family, he had to extract resin from about 3000 trees. The workdays usually began before sunrise with the commute to the work area in the pine forest, and Resin Workers would often work 10 to 12 hours.
The tree resin was melted from the raw resin balm in special huts through a distillation process, the so-called the "Boiling Pitch". During this process, the impurities were first skimmed off or sieved before the oil and water were evaporated and collected in a collection container. The lighter turpentine oil floated to the top of the mixture during this process, and it was poured out. The "Boiling Pitch," now freed from water and Turpentine oils, became a dark yellow, hard and brittle mass after cooling—this is known as: "Rosin."
This collected Terpentine Oil and the Rosin were primarily used in the paper, varnish, soap, wire, and shoe-polish industries.
Seasonal Work and Working Methods
The work of a Resin Worker varied based on the season. The most important work in the winter was the preparation of equipment, especially the making of pitch notches via the use of a special tool called a "Notch Planar." Pitch notches were wooden planks, which were inserted against the tree after bark removal (between the bare trunk and the remaining bark on the edges) to help direct resin flow. The most complex work took place in the spring, when the actual resin collection was done, and different methods were used.
Pitch Container Variations and General Collection Methods
"Grandl" or "Scrap" Method
In the earliest method of resin extraction, the resin was collected near the base of the trunk in simple earthen pits smeared with clay. Because this led to resin contamination, the "Grandl" or Scrap Method was eventually developed. When using this method, the Resin Worker would create a recess—which was called a "Scrap"—out of the wood near the ground with a hoe. This Scrap became the new site of resin collection. Since this new resin container had to be smooth and clean, the Scrap was smoothed with a narrower, rounded hoe (called the "moon" or "scrap" hoe). The resulting wood chips from this process were removed via the use of a pointed stick—referred to as the "Rowisch"—which at the same time served as a counting tool: after each new scrap was cut, the Resin Worker would carve an indentation into the stick so that the number of trees that had been extracted was always known.
With the "Adze," which later became the guild symbol of the Pecherei profession, and with a hoe, the Resin Worker subsequently removed the bark from the tree trunk. In order to be able to direct the resin flow into the resin-collection area (the Scrap), pitch notches had to be inserted across the trunk.
About three times every two weeks, from spring to early autumn, de-barking was the oldest working method. The Resin Worker removed the bark piece-by-piece with a special de-barking Adze down to the trunk so that the surface free from bark continued to grow and the resin flow remained upright.
Depending on its size, a Scrap could take up between 0.25 and 0.35 kg of pitch. A tree worked in this way could provide pitch for 12 to 18 years of resin extraction.
The Beer Mug Method
In the inter-war period, the transition from the "Scrap" to the "Beer Mug" method began, in which pitch mugs were used for the resin collection. To do this, the bark of new pitch trees, called the "Heurigen", had to be trimmed from the ground up with a hoe. During this process, the bark was removed from about a third of the circumference of the trunk first with an axe and then with the Rintler (which is essentially a scraper) so that a V-shaped demarcation was created.
Then, the Resin Worker had to create an elongated recess on the sides of the tree trunk to accommodate the pitch notches, chopping and pulling them in. Just below the narrowest point, an opening was hacked out to hold the pitch-collecting mug; a pitch nail was hammered in just below it, and finally the collecting mug with its lid was put in. The tree was now ready for resin extraction and, as described above, had to be de-barked at regular intervals.
The trees that had been pitched for several years were processed in a similar way.
General Description of Bark Removal Methods
While the Scrap and Beer Mug methods were essentially the two approaches used in setting up a tree for resin extraction, some variation existed in terms of how the bark was removed and how the resin flow was managed. Some of these bark removal and resin flow methods are described below.
Adze-based Bark Removal (de-barking):
As mentioned in the collection methods described above, bark was originally removed via the use of an Adze or similar tools. This, however, was time-consuming and required much effort, as only small pieces of bark could be removed per hit with this device.
The Planing Method
Due to the strenuous nature of the Adze-based bark removal, the planing method was developed. Not only was it less strenuous; it also took less time.
The working method for new pitch trees as well as those that had been worked on for several years remained the same as described above, only planing was used instead of the usual, Adze-based, de-barking. With the plane (a tool for smoothing surfaces), the Resin Worker cut a wide, flat chunk from the trunk with a single cut. When de-barking in earlier methods, this could only be achieved with many hits from the Adze.
The Groove Method
As with all processing methods, the upper section of tree bark had to be removed beforehand for the grooving method. Then, the Resin Worker removed a layer of bark several millimeters thick with a scraper. A precise cut was important. With this planing process, no contiguous surfaces were created, but rather V-shaped grooves within the trunk itself. This saved the Resin Worker from inserting the pitch notches, as the resin could flow through the grooves into the pitch mug.
Although the Groove Method saved work and time by eliminating chopping, it was only used sporadically in southern Lower Austria, as the yield was up to 50% lower than that of the two other resin extraction approaches, namely adze-based de-barking and planing. A big problem with the grooving process was the clogging of the grooves with resin.
Other Tools and Facilities
The ladder was an indispensable tool for working on trees that had been pitched for several years. It was made from two thin, long pine trees that served as stiles and tough dogwood for the rungs. A professional extractor climbed up to 22 rungs of the ladder, which corresponds to a height of 6 m, several hundred times a day, worked the trunk and then slid down with the leather slip patches attached to the thighs and knees.
According to old custom, a wooden Pecher hut was built in the middle of the forest. It resembled a wood chopper's hut and was mainly used for protection and refuge in bad weather. Inside there was usually a roughly timbered table and a bench. The Resin Worker ate here occasionally. Now and then, there was also a stove. The Pecher went home nearly every day; only in exceptional cases did he spend the night in the hut. A ladder area was set up so that the ladders needed to work on the trees of different heights did not always have to be taken home.
Citations (Weblinks)
Resins
Lower Austria | Austrian Resin Extraction | [
"Physics"
] | 2,243 | [
"Amorphous solids",
"Unsolved problems in physics",
"Resins"
] |
65,085,146 | https://en.wikipedia.org/wiki/Carbon%20Copy%20%28software%29 | Carbon Copy was "a remote control/communications program" with for-its-day advanced features for remote screen sharing, background file transfer, and "movable chat windows".
Overview
The New York Times described it thus: "you can sit at the console of either machine and call up
the programs and files stored on the other". Computerworld called it "a package that mirrors every action a user takes on two connected PCs".
Part of its user base was acquired via inclusion as bonus software for a modem that could communicate at "300, 1200 and 2400 baud."
Carbon Copy's vendor, Meridian Technology, was acquired by Microcom in early 1988, and accepted tax credits to move software duplication and
packaging of Carbon Copy to Puerto Rico. Meridian had a British subsidiary, also acquired by Microcom.
History
Computerworld covered the flow of features and newer releases: 3.0 (1986), 1987, 1989. By 1991, although Version 5.2.2 was still actively marketed, Version 6.0 was released to coincide with the release of MS/DOS 5.0.
By 1994, DOS versions topped out at 6.0, and the 2.0 version of Carbon Copy Plus for Windows was available. A version for the Macintosh platform was also available, dubbed "Carbon Copy for the Mac".
See also
BLAST (protocol)
Kermit (protocol)
References
History of software
History of telecommunications | Carbon Copy (software) | [
"Technology"
] | 291 | [
"Computing stubs",
"History of software",
"Software stubs",
"History of computing"
] |
65,088,597 | https://en.wikipedia.org/wiki/Moto%20G9 | Moto G9 (stylized by Motorola as moto g9) is a series of Android smartphones developed by Motorola Mobility, a subsidiary of Lenovo. It is the ninth generation of the Moto G family.
Specifications
Some specifications such as wireless technologies and storage will differ between regions.
References
Motorola smartphones
Mobile phones introduced in 2020
Android (operating system) devices
Mobile phones with multiple rear cameras | Moto G9 | [
"Technology"
] | 81 | [
"Mobile technology stubs",
"Mobile phone stubs"
] |
65,089,532 | https://en.wikipedia.org/wiki/Bengal%20temple%20architecture | Bengal temple architecture also known as Malla dynasty architecture is about temple styles developed and used in Bengal, particularly the chala, ratna and dalan temples.
Background
According to David J. McCutchion, historically the religious architecture in Bengal may be divided into three periods: the early Hindu period (up to the end of the 12th century, or may be a little later in certain areas), the Sultanate period (14th to early 16th century), and the Hindu revival period (16th to 19th century). "The coming of the Muslims at the beginning of the 13th century marked a sharp break with the past. After an initial century or so of anarchy and consolidation ... Bengal as we know it today became an independent entity for the first time. During the following two centuries a distinctive Bengali culture took shape".
"Between the earlier and later Hindu periods astonishing religious changes took place in Bengal: the worship of Vishnu gave way to that of Radha-Krishna, of Chamunda to that of Kali; Surya fell entirely out of favour; curious folk cults like that of Dharmaraja or Dakshina Raya arose." The temples of pre-Muslim period can be called tall curvilinear rekha deul. Another equally common group of temples found in Pre-Mughal Bengal are temples with tiered pyramidal tower known as pirha or bhadra deul. During the earlier and later Hindu period religious changes took place in Bengal which also brought some changes in the temple architecture. In their places of the other temple styles appeared two entirely new styles- hut style and the pinnacled style.
Chala temple
The ek-bangla or do-chala consists of a hut with two sloping roofs, following the pattern of huts, mostly in East Bengal villages. The stone temple at Garui in Bardhaman district of West Bengal, built in the 14th century, has a Bengal hut shaped roof. Two huts, one forming a porch in front and the other being the shrine at the back constitutes the jor-bangla design – "Bengal's most distinctive contribution to temple architecture".
In West Bengal, the hut roof generally has four sides and the char-chala temple is built on this model. If a miniature duplicate is built on the roof, it becomes an at-chala. The char-chala temple form was well established by the 17th century. Apart from the main shrines, nahabatkhana or entrance gateways also have a do-chala roof.
Ratna temple
The curved roof of a ratna temple "is surmounted by one or more towers or pinnacles called ratna (jewel). The simplest form has a single central tower (eka-ratna), to which may be added four more at the corners (pancha-ratna)". The number of towers or pinnacles can be increased up to a maximum of twenty-five. The ratna style came up in the 15th-16th century. Muslim domed temples are very rare, except possibly in Cooch Behar.
"Ratna style temples are the composite type of architecture... The lower part of the temple has all the features of the curved cornices and a short pointed spire crowns the roof and this will be adorned with the introduction of ratnas or kiosks."
Dalan temple
The flat-roofed (dalan) temples "with their heavy cornices on S-curved brackets ... have a long Indo-Islamic palace and temple tradition". They were influenced by European ideas in the 19th century. The design was easier to build. In the long run, this style lost its special identity as religious architecture and got mixed up with domestic architecture. In some temples a dome has been added,
Rekha deul
The traditional rekha deul is predominant in the western districts of Bengal. Some are smooth curvilinear and others are ridged curvilinear. In the smooth type, the sikhara is free of horizontal bars and in ridged type, it is closely ridged with bars. The ratha projections are generally deep and spaced, and sometimes decorated. The crowning amalaka is generally large and flat. There are large and small types of deuls. Many of the very small types dispense with the complicated styling. It went on developing from the late 7th century or early 8th century to around the 12th century, increasing its complexity and height but retaining its basic features.
Grouped temple
Temples of identical style and size are sometimes grouped together. Two identical Shiva temples are called a Jora Shiva temple. Groups of four, six and twelve Shiva temples are quite popular. The most elaborate groups existing have 108 Shiva temples.
References
Sacral architecture
Culture of West Bengal
Buildings and structures in Bangladesh
Hindu temple architecture
Indian architectural styles | Bengal temple architecture | [
"Engineering"
] | 979 | [
"Sacral architecture",
"Architecture"
] |
65,090,606 | https://en.wikipedia.org/wiki/Samsung%20Galaxy%20Watch%20series | The Samsung Galaxy Watch series is a line of smartwatches designed and produced by Samsung Electronics. The line features various health, fitness, and fashion related features, and is integrated with Samsung's other products under the Samsung Galaxy brand. The series is the successor to the previous Samsung Gear watches.
The first smartwatch under this series, the Galaxy Watch, was released in August 2018.
The Galaxy Watch series shares the circular form factor of the Samsung Gear S2 and S3, as a result much of the OS features are shared between the Gear S2 and S3 and the Galaxy Watch.
Operating system
For the original Galaxy Watch, the Watch Active and Active2 and the Watch3, Samsung used its in-house developed Tizen OS, which it previously used for the Samsung Gear series of watches.
With the announcement of the Galaxy Watch4 and Galaxy Watch4 Classic in August 2021, Samsung entered into a partnership with Google to work together on Wear OS bringing some of the features from Samsung's Tizen with One UI Watch to Wear OS, while other features remained exclusive to Samsung's own customization to the OS.
Specifications
Galaxy Watch
The baseline Galaxy Watch series started as the lower cost Galaxy Watch Active line. Unlike the original Galaxy Watch and Galaxy Watch3, these watches were missing the rotating bezel. The Active line put more focus on fitness and wellness. With the 4th generation, the "Active" label was dropped in favor of the form-factor becoming the base smartwatch in the series. The Galaxy Watch4 was used as the base for the Galaxy Watch FE in 2024.
The Watch5 introduced a temperature sensor and added support for fast charging.
The Watch6 had an increased battery capacity and increased RAM.
The Watch7 had increased storage, an improved sensor, and support for faster charging.
The Watch5 Pro and Watch Ultra are the only watches to support GPX routes.
Galaxy Watch Classic
The Galaxy Watch Classic line supersedes the Samsung Gear S2 and S3, inheriting the rotating bezel introduced with the Gear S2. For the first and third generation of the Galaxy Watch line, it functioned as the base smartwatch of the series. The classic line did not get a device in the second generation. However, as of the 4th generation, the original design was promoted to take on a more premium spot in the line-up. The Watch4 Classic and Watch6 Classic both continue to use the rotating bezel as an optional navigation interface. The Watch5 Pro and Watch Ultra omit the feature, both the 5th and 7th generation do not have a Classic variant of the smartwatch.
Galaxy Watch FE
The Galaxy Watch FE ("Fan Edition") is a cheaper smartwatch. The original Galaxy Watch FE is based on the Galaxy Watch4 with the only physical difference being the use of sapphire crystal as glass instead of the Corning Gorilla Glass DX+ used on the original Watch4.
References
Consumer electronics brands
Smartwatches
Samsung wearable devices
Wearable devices | Samsung Galaxy Watch series | [
"Technology"
] | 603 | [
"Smartwatches"
] |
66,377,910 | https://en.wikipedia.org/wiki/Zetkin%20Collective | The Zetkin Collective is a research group made up of activists and academics. It focuses on analyzing and explaining the political ecology of the far-right, including ecofascism and Malthusianism as well as climate change denial and eco-nationalism. The group began within the human ecology department of Lund University in Sweden.
The collective is named after Clara Zetkin, a German Marxist theorist who studied the Italian fascist movement in 1923. Its work draws on the definition of fascism created by Zetkin.
The collective authored the book White Skin, Black Fuel: On the Danger of Fossil Fascism, which was published by Verso Press. In 2020, the French-language edition Fascisme fossile: L'extrême droite, l'énergie, le climat was published by La Fabrique and named a book of the day by Philosophie Magazine.
References
External links
https://thezetkincollective.org/
Political ecology
Lund University | Zetkin Collective | [
"Environmental_science"
] | 203 | [
"Political ecology",
"Environmental social science"
] |
66,379,796 | https://en.wikipedia.org/wiki/Ferraris%27%20motor | In 1885, Galileo Ferraris demonstrated an induction motor that also involved using two pairs of electromagnets to create a rotating magnetic field, though he did this independently of Baily. His motor more closely resembled modern ones in that the electromagnets surrounded a cylinder. More significantly, however, he proposed creating a true rotating magnetic field for it by supplying two sine wave alternating currents 90° apart. He gave his first public demonstration of the motor in 1888.
History and description
Professor Galileo Ferraris, of Turin, had already in 1885, arrived at the same fundamental ideas as those of Baily and of Deprez. But the result was more fruitful, inasmuch as he, without knowing of the work of either, united both sets of ideas. Like Baily he proposed to produce rotation of a copper conductor by means of eddy-currents induced in it by a progressively shifted magnetic field; and this progressively shifted magnetic field he proposed to generate as a true rotating field by combining at right angles to one another two alternate currents which differed by a quarter-period from one another.
In 1885, Professor Ferraris constructed the motor depicted in plan in Fig 1, which was not, however, publicly shown till 1888. It was exhibited in 1893 at the World's Fair at Chicago. It consisted of two pairs of electromagnets A A and B B', having a common yoke made by winding iron wire around the exterior. Two alternate currents differing in phase were led into these two circuits, and the pivoted central body was observed to revolve.
Ferraris's first publication was in March 1888, entitled Electrodynamic rotations produced by means of alternate currents. After expounding the geometric theory of the rotatory magnetic field, he suggested that a simple way of procuring the desired phase-currents would be to branch the circuit of an alternate current into two parts, into one of which should be inserted a resistance without self-induction, into the other a coil of much self-induction but of small resistance. The two windings of the motor should be respectively introduced into these two branches. The difference of phase thus produced would be sufficiently near to 90° to be effective. He expressed the opinion that in this way one might obtain all the effects that can be obtained by the rotation of a magnet. He then described the following experiments which were made in the autumn of 1885.
Two flat coils, one of thick wire, the other of thinner wire, represented diagrammatically at A A and B B of Fig. 1, were set at right angles to one another. Into the first was brought a current from the primary of a Gaulard's transformer, and into the second the current from the secondary, with more or less non-inductive resistance. In the central space was suspended a small hollow closed cylinder of copper. If the current was turned on in one only of the two windings the cylinder remained immovable, but on turning on the second current it at once began to rotate. The sense of the rotation could be reversed by simply changing, with a reversing-switch, the connections of the second coil. The same results were found to follow when a cylinder of iron was substituted for that of copper. A laminated iron cylinder built up of insulated disks also turned. Then followed suggestions for constructing alternate current motors on this principle but of modified form; for, as Professor Ferraris remarked, it was evident that a motor thus made could not have any importance as a means of industrial transformation of power. He therefore designed a larger model, having as its rotating part a copper cylinder weighing 10 lbs, having a length of 18 cm, and a diameter of 8,9 cm, borne on a horizontal shaft 1 cm in diameter. It was surrounded by two sets of coils A A and B B at right angles to one another, as in the Fig. 2. It was, however, of but small power. Ferraris discussed the elementary theory of the apparatus, pointing out that the inductive action would be proportional to the slip, that is to say to the difference between the angular velocity of the magnetic field and that of the rotating cylinder, that the induced current in the rotating metal would also be proportional to this; and that the power of the motor is proportional jointly to the slip and to the velocity of the rotating part. Ferraris also suggested measuring instruments for alternate currents based on this principle. Lastly he succeeded in producing rotation in a mass of mercury placed in a vessel in the rotatory field. In 1894 Ferraris published another discussion of the theory of these motors.
See also
Arago's Rotations
Timeline of the Electric Motor
Rotating magnetic Field
Induction Motor
References
External links
Inventing The Induction Motor
Electric motors
Electromagnetism
19th-century inventions | Ferraris' motor | [
"Physics",
"Technology",
"Engineering"
] | 977 | [
"Electromagnetism",
"Physical phenomena",
"Engines",
"Electric motors",
"Fundamental interactions",
"Electrical engineering"
] |
66,381,096 | https://en.wikipedia.org/wiki/Rough-and-tumble%20play | Rough-and-tumble play, also called play fighting, is a form of play where participants compete with one another attempting to obtain certain advantages (such as biting or pushing the opponent onto the ground) but play in this way without the severity of genuine fighting (which rough-and-tumble play resembles). Rough-and-tumble play is one of the most common forms of play in both humans and non-human animals.
It has been pointed out that despite its apparent aggressiveness, rough-and-tumble play is helpful for encouraging cooperative behavior and cultivation of social skills. For rough-and-tumble play to remain "play" (instead of spiraling into a real fight), there has to be cooperation (e.g., with participants agreeing to not actually exert forces in pretend punches). Sometimes, one participant may push or hit harder than expected, and then the other participants will have to decide whether it was an unintended mistake or a malicious transgression. Thus, rough-and-tumble play involves considerable social reasoning and judgment.
Sexual Dimorphism
This form of play exhibits notable sexual dimorphism in many mammalian species, including humans. Males typically engage in this type of play more frequently and intensively than females, a pattern observed across diverse taxa ranging from rodents to primates. This dimorphism is thought to result from the influence of prenatal and early postnatal hormones, particularly androgens like testosterone, which shape the neural circuits governing social and play behavior. Researchers propose that these sex differences may have evolutionary significance, contributing to the development of motor skills, dominance behaviors, and social strategies that were advantageous for reproductive success in ancestral environments.
Mammals
Carnivora
Male carnivores tend to have higher rates of rough-and-tumble play compared to females. This is potentially due to the fact that males are typically larger, due to polygamous or promiscuous mating systems, as well as energy requirements imposed on females by feeding young.
Conflicting results have arisen from Pinnipeds. Some studies report that male and female pups do not show significant differences in engagement in rough-and-tumble play, while others suggest that male pups spend more time engaged in dyadic play bouts. Male Galapagos fur seal pups (Arctocephalus galapagoensis) are reported to engage in play bouts that are twice as long as those seen in female conspecifics. Rough-and-tumble play has also been observed in South American fur seals (Arctocephalus australis) and harbour seals (Phoca vitulina).
Rough-and-tumble play has been reported in the following canine species: domestic dogs (Canis familiaris), coyotes (Canis latrans), wolves (Canis lupus occidentalis), bush dogs (Speothos venaticus), crab-eating foxes (Cerdocyon thous), and maned wolves (Chrysocyon brachyurus). In domestic puppies, males initiate more often than females and will initiate more often in mixed-sex dyads. No sexed differences have been reported in wolves, bush dogs, crab-eating foxes or maned wolves.
In Felidae, rough-and-tumble play has been reported in the Eurasian lynx (Lynx lynx), Far-Eastern wild cat (Prionailurus bengalensiseuplilurus), and domestic cat (Felis catus), though no known sexed differences occur between male and female kittens. Meerkats (Suricata suricatta) also show no sexual dimorphism in play frequencies or initiations.
Primates
Primates are known for their relatively long juvenile development periods, which are often associated with juvenile play. Long juvenile periods, small litter sizes, long intervals between births, extended lifespans and high investment in offsprings mean that primates are often an ideal model for looking at play behaviour.
In the ring-tailed lemur (Lemur catta), female infants are found to engage in social play more frequently than male conspecifics, although there are some conflicting reports.
In the family Atelidae, black-handed spider monkeys (Ateles geofroyi) are reported to have male infants are play more frequently than females and are more likely to engage in play bouts. Comparatively, in the Yucatán black howler monkey (Alouatta pigra), there are no known sexed differences. In the mantled howler monkey (Alouatta palliata), males have been reported to play less.
In the family Callitrichidae, males are reported to play more than female common marmosets (Callithrix jacchus). In contrast, female saddle-backed tamarins (Saguinus fuscicollis) are reported to play more often than males.
In the Cebidae family, male tufted capuchins (Cebus apella) spend more time wrestling and chasing than females. This pattern is seen again in the squirrel monkey (Saimiri sciureus).
Captive coppery titi monkeys (Callicebus cupreus) have not shown any sex-related differences in juvenile rough-and-tumble play.
Male Japanese macaques (Macaca fuscata) play and initiate more frequently than female conspecifics. This pattern is reported again in the rhesus macaque (Macaca mulata), and that males also had higher frequencies of success in play bouts. These patterns are also reported in the stumptail (Macaca arctoides) and crested (Macaca nigra) macaques.
Juvenile Yellow baboons (Papio cynocephalus) appear to spend the same amount of time rough-and-tumble playing, regardless of sex. In the Hamadryas baboon (Papio hamadryas), males spend more time engaged in dyadic play. This is seen again in the Olive baboon (Papio anubis), where males also engage more frequently in mouth-and-wrestle play.
Geladas (Theropithecus gelada) show no sexed differences in rough-and-tumble play, although some reports suggest that in the wild, males play slightly more often than females.
Vervets (Cercopithecus aethiops) have juvenile males that engage more frequently and more aggressively in rough-and-tumble play. It is suggested however that these patterns are influenced heavily by age in this species, and that females engage in more social play later in their development (48 to 61 months).
Multiple guenon species are known to show rough-and-tumble play, with a male bias. This includes: the samango monkey (Cercopithecus mitis erythrarchus), the talapoin (Miopithecus talapoin), patas (Erythrocebus patas), the redtail monkey (Cercopithecus ascanius) and the blue monkey (Cercopithecus mitis stuhlmanni).
Male sooty mangabeys (Cercocebus atys) are reported to play more often than females. In contrast, there are no reported sex differences in play in immature grey-cheeked mangabeys (Lophocebus albigena).
Sichuan snub-nosed monkeys (Rhinopithecus roxellana) have a male bias towards rough-and-tumble play. There is no reported bias in the similarly related species the black-and-white colobus monkeys (Colobus guereza) or red colobus monkeys (Procolobus rufomitratus).
In chimpanzees (Pan troglodytes), males are known to engage more frequently in play than females. Age, setting, components of play and age group are all known factors that affect how long and how often immature chimpanzees engage in rough-and-tumble play.
Rodents
Rough-and-tumble play has been observed in captive prairie voles (Microtus ochrogaster) and wild capybara (Hydrochoerus hydrochaeris), irrespective of sex. In wild yellow-bellied marmosets (Marmota flaviventris), male yearlings participate in bouts more frequently than female conspecifics.
In Columbian ground squirrels (Spermophilus columbianus), reports vary, with some suggesting that males engage and participate in rough-and-tumble play more frequently, while others suggest there is no significant observed sex bias. Belding's ground squirrels (Urocitellus beldingi) also engage in juvenile rough-and-tumble play.
Results from captive golden hamsters (Mesocricetus auratus) suggest that males engage more frequently in bouts and longer than females. This pattern is also observed in the juvenile rough-and-tumble play behavior of captive hooded rats (Rattus norvegicus).
Cetaceans (Whales and dolphins)
Low levels of social play have been recorded in both sexes of bottlenose dolphin (Tursiops truncatus) calves.
Rough-and-tumble play has been observed in belugas (Delphinapterus leucas), in both juveniles and adults.
Chiroptera (Bats)
Rough-and-tumble play has been observed in the common vampire bat (Desmodus rotundus), with a male bias towards initiation.
Dasyuromorphia (Carnivorous marsupials)
In captive kowaris (Dasyuroides byrnie), rough-and-tumble play has been observed in both sexes of juveniles. Similarly, juvenile rough-and-tumble play has been reported in both sexes of spotted-tail quolls (Dasyurus maculatus).
Diprotodontia (Marsupials)
In captive, red-necked wallabies (Macropus rufogriseus banksianus) rough-and-tumble play is reported. This play behaviour is more common in males, with juvenile females rarely observed engaging.
Playfighting has been reported in the red kangaroo (Macropus rufus) between mother and offspring.
Perissodactyla (Odd-toed ungulates)
Multiple studies have investigated rough-and-tumble play in horses (Equus caballus). One study reports that male Jeju pony foals are more likely to engage in this kind of play after grooming compared to female conspecifics. Another study reports that juvenile male Icelandic horses engage in rough-and-tumble play more frequently than juvenile females. This pattern has also been observed in Welsh ponies, Camargue's and feral horses.
Artiodactyla (Even-toed ungulates)
Play-fighting has been reported in adult and juvenile male goitered gazelles (Gazella subgutturosa). Similarly, it is also reported in juvenile pronghorns (Antilocapra americana) and guanacos (Lama guanicoe).
Proboscidea (Elephants)
Rough-and-tumble play is observed in both African (Loxodonta africana) and Asian elephant (Elephas maximus) calves. It has been noted that there is an increase in male bias in captive animals compared to wild.
References
External links
Rough and Tumble Play. Scholarpedia.
Play (activity)
Aggression
Ethology
Learning
Childhood
Mock combat
Fight play | Rough-and-tumble play | [
"Biology"
] | 2,390 | [
"Behavior",
"Ethology",
"Behavioural sciences",
"Aggression",
"Play (activity)",
"Human behavior"
] |
66,381,155 | https://en.wikipedia.org/wiki/Clear%20Mobile | Clear Mobile is a mobile telephone network running as a mobile virtual network operator (MVNO) using Vodafone's Irish network. Vodafone owns Clear Mobile. Clear Mobile was launched on 14 January 2021.
Products and services
Since launch, Clear Mobile has offered one product, which is a sim-only mobile contract. The package is post-paid and includes unlimited calls to Irish mobiles and landlines, unlimited texts to Irish mobiles, unlimited 4G data with a maximum download speed of 5 Mbit/s and 10 GB EU data.
Customer service
Clear Mobile has no customer service phone lines. All support is via social media and online channels.
References
Telecommunications
Irish companies established in 2021
Mobile virtual network operators
Mobile telecommunications networks | Clear Mobile | [
"Technology"
] | 150 | [
"Information and communications technology",
"Mobile telecommunications",
"Mobile telecommunications networks",
"Telecommunications"
] |
66,382,863 | https://en.wikipedia.org/wiki/Free%20choice%20inference | Free choice is a phenomenon in natural language where a linguistic disjunction appears to receive a logical conjunctive interpretation when it interacts with a modal operator. For example, the following English sentences can be interpreted to mean that the addressee can watch a movie and that they can also play video games, depending on their preference:
You can watch a movie or play video games.
You can watch a movie or you can play video games.
Free choice inferences are a major topic of research in formal semantics and philosophical logic because they are not valid in classical systems of modal logic. If they were valid, then the semantics of natural language would validate the Free Choice Principle.
Free Choice Principle:
This symbolic logic formula above is not valid in classical modal logic: Adding this principle as an axiom to standard modal logics would allow one to conclude from , for any and . This observation is known as the Paradox of Free Choice. To resolve this paradox, some researchers have proposed analyses of free choice within nonclassical frameworks such as dynamic semantics, linear logic, alternative semantics, and inquisitive semantics. Others have proposed ways of deriving free choice inferences as scalar implicatures which arise on the basis of classical lexical entries for disjunction and modality.
Free choice inferences are most widely studied for deontic modals, but also arise with other flavors of modality as well as imperatives, conditionals, and other kinds of operators. Indefinite noun phrases give rise to a similar inference which is also referred to as "free choice" though researchers disagree as to whether it forms a natural class with disjunctive free choice.
See also
Deontic logic
Disjunction
Hans Kamp
Modal logic
Ross's paradox
Simplification of disjunctive antecedents
Sluicing
Notes
Semantics
Deontic logic
Philosophical logic
Mathematical logic
Rules of inference
Formal semantics (natural language) | Free choice inference | [
"Mathematics"
] | 396 | [
"Mathematical logic",
"Modal logic",
"Rules of inference",
"Proof theory"
] |
66,385,447 | https://en.wikipedia.org/wiki/Scandinavian%20Logic%20Society | The Scandinavian Logic Society, abbreviated as SLS, is a not-for-profit organization with objective to organize, promote, and support logic-related events and other activities of relevance for the development of logic-related research and education in the Nordic Region of Europe.
The society is a member of the Division of Logic, Methodology and Philosophy of Science and Technology.
History
The SLS was founded on 20 August 2012, at the 8th Scandinavian Logic Symposium in Roskilde, Denmark. Today the society has its seat in Stockholm, Sweden. It unites academics from Denmark, Finland, Iceland, Norway and Sweden working primarily on theory and applications of logic to computer science, philosophy, mathematics and linguistics.
Presidents
The SLS is led by Executive Committee.
The presidents of the SLS:
2012-2017 Dag Normann
2017–present Valentin Goranko
Main activities
Scandinavian Logic Symposium (SLSS)
The Society organizes regular Scandinavian Logic Symposia (SLSS) every 2–4 years on a geographically rotating principle. The primary aim of the Symposium is to promote research in the field of logic (broadly conceived) carried out in research communities in Scandinavia.
Past symposia
1968: 1st symposium in Åbo/Turku, Finland
1971: 2nd symposium in Oslo, Norway
1973: 3rd symposium in Uppsala, Sweden
1976: 4th symposium in Jyväskylä, Finland
1979: 5th symposium in Aalborg, Denmark
1982: 6th symposium in Telemark, Norway
1996: 7th symposium in Uppsala, Sweden
2012: 8th symposium in Roskilde, Denmark
2014: 9th symposium in Tampere, Finland
2018: 10th symposium in Gothenburg, Sweden
2022: 11th symposium in Bergen, Norway
11th symposium scheduled for 2020 in Bergen, Norway, was postponed for 2022 due to pandemic of COVID-19
Nordic Logic (Summer) School (NLS)
The Society organizes regular Nordic Logic Schools every 2–4 years. The intended audience is advanced master students, PhD-students, postdocs and experienced researchers wishing to learn the state of the art in a particular subject.
Past schools
2013: 1st summer school in Nordfjordeid, Norway
2015: 2nd summer school in Helsinki, Finland
2017: 3rd summer school in Stockholm, Sweden
2022: 4th summer school in Bergen, Norway
4th summer school scheduled for 2020 in Bergen, Norway, was postponed for 2022 due to pandemic of COVID-19
General meetings of the SLS
General meetings of the Society are held regularly during the Scandinavian Logic Symposium.
Membership
Membership in the SLS is open to all interested persons who agree with and support the objectives of the Society.
See also
International Union of History and Philosophy of Science
Association for Symbolic Logic
World Logic Day
Thoralf Skolem
References
External links
SLS official website
Icelandic Center of Excellence in Theoretical Computer Science (ICE-TCS)
Copenhagen Association for Dynamics, Interaction, Logic, Language and Computation (CADILLAC)
Bergen Logic Group
The Logic and Artificial Intelligence (LAI) group, Bergen University
The Skolem Lecture
CLLAM – Centre for Logic, Language, and Mind
The Stockholm Logic Seminar
Information technology organizations based in Europe
Mathematical logic organizations
Philosophical logic
Philosophy organizations
Organizations established in 2012
Organizations based in Sweden
Logic organizations
2012 establishments in Sweden | Scandinavian Logic Society | [
"Mathematics"
] | 654 | [
"Mathematical logic",
"Mathematical logic organizations"
] |
66,386,846 | https://en.wikipedia.org/wiki/Huprine%20X | Huprine X is a synthetic cholinergic compound developed as a hybrid between the natural product Huperzine A and the synthetic drug tacrine. It is one of the most potent reversible inhibitors of acetylcholinesterase known, with a binding affinity of 0.026nM, as well as showing direct agonist activity at both nicotinic and muscarinic acetylcholine receptors. In animal studies it has nootropic and neuroprotective effects, and is used in research into Alzheimer's disease, and although huprine X itself has not been researched for medical use in humans, a large family of related derivatives have been developed.
References
Acetylcholinesterase inhibitors
Heterocyclic compounds with 4 rings
Chloroarenes
Amines
Nitrogen heterocycles | Huprine X | [
"Chemistry"
] | 174 | [
"Pharmacology",
"Functional groups",
"Medicinal chemistry stubs",
"Amines",
"Pharmacology stubs",
"Bases (chemistry)"
] |
66,387,043 | https://en.wikipedia.org/wiki/Rolling%20hairpin%20replication | Rolling hairpin replication (RHR) is a unidirectional, strand displacement form of DNA replication used by parvoviruses, a group of viruses that constitute the family Parvoviridae. Parvoviruses have linear, single-stranded DNA (ssDNA) genomes in which the coding portion of the genome is flanked by telomeres at each end that form hairpin loops. During RHR, these hairpin loops repeatedly unfold and refold to change the direction of DNA replication so that replication progresses in a continuous manner back and forth across the genome. RHR is initiated and terminated by an endonuclease encoded by parvoviruses that is variously called NS1 or Rep, and RHR is similar to rolling circle replication, which is used by ssDNA viruses that have circular genomes.
Before RHR begins, a host cell DNA polymerase converts the genome to a duplex form in which the coding portion is double-stranded and connected to the terminal hairpins. From there, messenger RNA (mRNA) that encodes the viral initiator protein is transcribed and translated to synthesize the protein. The initiator protein commences RHR by binding to and nicking the genome in a region adjacent to a hairpin called the origin and establishing a replication fork with its helicase activity. Nicking leads to the hairpin unfolding into a linear, extended form. The telomere is then replicated and both strands of the telomere refold back in on themselves to their original turn-around forms. This repositions the replication fork to switch templates to the other strand and move in the opposite direction. Upon reaching the other end, the same process of unfolding, replication, and refolding occurs.
Parvoviruses vary in whether both hairpins are the same or different. Homotelomeric parvoviruses such as adeno-associated viruses (AAV), i.e. those that have identical or similar telomeres, have both ends replicated by terminal resolution, the previously described process. Heterotelomeric parvoviruses such as minute virus of mice (MVM), i.e. those that have different telomeres, have one end replicated by terminal resolution and the other by an asymmetric process called junction resolution. During asymmetric junction resolution, the duplex extended form of the telomere reorganizes into a cruciform-shaped junction, and the correct orientation of the telomere is replicated off the lower arm of the cruciform. As a result of RHR, a replicative molecule that contains numerous copies of the genomes is synthesized. The initiator protein periodically excises progeny ssDNA genomes from this replicative concatemer.
Background
Parvoviruses are a family of DNA viruses that have single-stranded DNA (ssDNA) genomes enclosed in rugged, icosahedral protein capsids 18–26 nanometers (nm) in diameter. Unlike most other ssDNA viruses, which have circular genomes that form a loop, parvoviruses have linear genomes with short terminal sequences at each end of the genome. These termini are capable of being formed into structures called hairpins or hairpin loops and consist of short, imperfect palindromes. Varying from virus to virus, the coding region of the genome is 4–6 kilobases (kb) in length, and the termini are 116–550 nucleotides (nt) in length each. The hairpin sequences provide most of the cis-acting information needed for DNA replication and packaging.
Parvovirus genomes may be either positive-sense or negative-sense. Some species, such as adeno-associated viruses (AAV) like AAV2, package a roughly equal number of positive-sense and negative-sense strands into virions, others, such as minute virus of mice (MVM), show preference toward packaging negative-sense strands, and others have varying proportions. Because of this disparity, the 5′-end (usually pronounced "five prime end") of the strand that encodes the non-structural proteins is called the "left end", and the 3′-end (usually pronounced "three prime end") is called the "right end". In reference to the negative-sense strand, the 3′-end is the left side and the 5′-end is the right side.
Parvoviruses replicate their genomes through a process called rolling hairpin replication (RHR), which is a unidirectional, strand displacement form of DNA replication. Before replication, the coding portion of the ssDNA genome is converted to a double-strand DNA (dsDNA) form, which is then cleaved by a viral protein to initiate replication. Sequential unfolding and refolding of the hairpin termini acts to reverse the direction of synthesis, which allows replication to go back and forth along the genome to synthesize a continuous duplex replicative form (RF) DNA intermediate. Progeny ssDNA genomes are then excised from the RF intermediate. While the general aspects of RHR are conserved across genera and species, the exact details likely vary.
Parvovirus genomes have distinct starting points of replication that contain palindromic DNA sequences. These sequences are able to alternate between inter- and intrastrand basepairing throughout replication, and they serve as self-priming telomeres at each end of the genome. They also contain two key sites necessary for replication used by the initiator protein: a binding site and a cleavage site. Telomere sequences have significant complexity and diversity, suggesting that they perform additional functions for many species. In MVM, for example, the left-end hairpin contains binding sites for transcription factors that modulate gene expression from an adjacent promoter. For AAV, the hairpins can bind to MRE11/Rad50/NBS1 (MRN) complexes and Ku70/80 heterodimers, which are involved in sensing and repairing DNA. In general, however, they have the same basic structure: imperfect palindromes in which a fully or primarily basepaired region terminates into an axial symmetry. These palindromes can fold into a variety of structures such as a Y-shaped structure and a cruciform-shaped structure. During replication, the termini act as hinges in which the imperfectly basepaired or partial cruciform regions surrounding the axis provide a favorable environment for unfolding and refolding of the hairpin.
Some parvoviruses, such as AAV2, are homotelomeric, meaning the two palindromic telomeres are similar or identical and form part of larger (inverted) terminal repeat sequences. Replication at each terminal ending is therefore similar. Other parvoviruses, such as MVM, are heterotelomeric, meaning they have two physically different telomeres. As a result, heterotelomeric parvoviruses tend to have a more complex replication process since the two telomeres have different replication processes. In general, homotelomeric parvoviruses replicate both ends via a process called terminal resolution, whereas heterotelomeric parvoviruses replicate one end by terminal resolution and the other end by an asymmetric process called junction resolution. Whether a genus is hetero- or homotelomeric, along with other genomic characteristics, is shown in the following table.
General process
The entire process of rolling hairpin replication, which has distinct, sequential stages, can be summarized as follows:
1. The coding portion of the genome is replicated, starting from the 3′-end of the 3′ hairpin, which acts as a primer, and continues until the newly synthesized strand is connected to the 5′-end of the 5′ hairpin, producing a duplex DNA molecule that has two strands of the coding portion of the genome.
2. mRNA that encodes the viral replication initiator protein is transcribed and subsequently translated to synthesize the protein.
3. The initiator protein binds to and cleaves the DNA within a region called the origin, which results in the hairpin unfolding into a linear, extended form. At the same time, the initiator protein establishes a replication fork with its helicase activity.
4. The extended-form hairpin is replicated to create an inverted copy of the telomere on the newly synthesized strand.
5. The two strands of that end refold back into two hairpins, which repositions the replication fork to switch templates and move in the opposite direction.
6. DNA replication continues in a linear manner from one end to the other using the opposite strand as a template.
7. Upon reaching the other end, that end's hairpin is unfolded and refolded to replicate the terminus and once again swap templates and change the direction of replication. This back-and-forth replication is continually repeated, producing a concatemer of multiple copies of the genome.
8. The viral initiator protein periodically excises individual genomic strands of DNA from the replicative concatemer.
9. Excised ssDNA genomes are packaged into newly constructed viral capsids.
Preparation for replication
Upon cell entry, a tether about 24 nucleotides in length that attaches the viral protein NS1, essential in replication, to the virion is cleaved off the virion to be reattached later. After cell entry, virions accumulate in the cell nucleus while the genome is still contained within the capsid. These capsids may be reconfigured to an open or transitioned state during entry. The exact mechanism by which the genome leaves the capsid is unclear. For AAV, it has been suggested that nuclear factors disassemble the capsid, whereas for MVM, it appears as if the genome is ejected in a 3′-to-5′ direction from an opening in the capsid called a portal.
Parvoviruses lack genes capable of inducing resting cells to enter their DNA synthesis phase (S-phase). Additionally, naked ssDNA is likely to be unstable, perceived as foreign by the host cell, or improperly replicated by host DNA repair. For these reasons, the genome must either be converted rapidly to its less obstructive, more stable duplex form or retained within the capsid until it is uncoated during S-phase. Typically, the latter occurs and virion remains silent in the nucleus until the host cell enters S-phase by itself. During this waiting period, virions may make use of certain strategies to evade host defense mechanisms to protect their hairpins and DNA to reach S-phase, though it is unclear how this occurs. Since the genome is packaged as ssDNA, creation of a complementary strand is necessary before gene expression.
DNA polymerases are only able to synthesize DNA in a 5′ to 3′ direction, and they require a basepair primer to begin synthesis. Parvoviruses address these limitations by using their termini as primers for complementary strand synthesis. A 3′ hydroxyl end of the left-hand (3′) terminus pairs with an internal base to prime initial DNA synthesis, resulting in the conversion of the ssDNA genome to its first duplex form. This is a monomeric double-stranded DNA molecule in which the two strands are covalently cross-linked to each other at the left-end by a single copy of the viral telomere. Synthesis of the duplex form precedes NS1 expression so that when the replication fork during initial complementary strand synthesis reaches the right (5′) end, it does not displace and copy the right-end hairpin. This allows the 3′-end of the new DNA strand to be covalently ligated to the 5′-end of the right hairpin by a host ligase, thereby creating the duplex molecule. During this step, the tether sequence that was present before viral entry into the cell is resynthesized.
Essential viral proteins and initiation
Once an infected cell enters S-phase, parvovirus genomes are converted to their duplex form by host replication machinery, and mRNA that encodes non-structural (NS) proteins is transcribed starting from a viral promoter (P4 for MVM). One of these NS proteins is usually called NS1 but also Rep1 or Rep68/78 for the genus Dependoparvovirus, which AAV belongs to. NS1 is a site-specific DNA binding protein that acts as the replication initiator protein via nickase activity. It also mediates excision of both ends of the genome from duplex RF intermediates via a transesterification reaction that introduces a nick into specific duplex origin sequences. Key components of NS1 include an HUH endonuclease domain toward the N-terminus of the protein and a superfamily 3 (SF3) helicase toward the C-terminus, as well as ATPase activity. It binds to ssDNA, RNA, and site-specifically on duplex DNA at reiterations of the tetranucleotide sequence 5′-ACCA-3′. These sequences are present in the viral replication origin sites and repeated at multiple sites throughout the genome in more or less degenerative forms.
NS1 nicks the covalently-closed right-end telomere via a transesterification reaction that liberates a basepaired 3′ nucleotide as a free hydroxyl (-OH). This reaction is assisted by a host DNA-binding protein from the high mobility group 1/2 (HMG1/2) family and is made in the replication origin, OriR, which was created by sequences in and immediately adjacent to the right hairpin. The left-end telomere of MVM, a heterotelomeric parvovirus, contains sequences that can give rise to replication origins in higher-order duplex intermediates, but these sequences are inactive in the hairpin terminus of the monomeric molecule, so NS1 always initiates replication at the right end.
The 3′-OH that is freed by nicking acts as a primer for the DNA polymerase to start complementary strand synthesis while NS1 remains covalently attached to the 5′-end via a tyrosine residue. Consequently, a copy of NS1 remains attached to the 5′-end of all RF and progeny DNA throughout replication, packaging, and virion release. NS1 is only able to bind to this specific site by assembling into homodimers or higher order multimers, which happens naturally with the addition of adenosine triphosphate (ATP) that is likely mediated by NS1's helicase domain. In vivo studies have shown that NS1 can form into a variety of oligomeric states, but it most likely assembles into hexamers to fulfill the functions of both the endonuclease domain and helicase domain.
Starting from the location at the nick, it is thought that NS1 organizes a replication fork and acts as the replicative 3′-to-5′ helicase. Near its C-terminus, NS1 contains an acidic transcriptional activation domain. This domain acts to upregulate transcription starting from a viral promoter (P38 for MVM) when NS1 is bound to a series of 5′-ACCA-3′ motifs, called the tar sequence, positioned upstream (toward the 5′-end) of the promoter unit, and via interaction with NS1 and various transcription factors. NS1 also recruits the cellular replication protein A (RPA) complex, which is essential for establishing the new replication fork and for binding and stabilizing displaced single strands.
While NS1 is the only non-structural protein essential for all parvoviruses, some have other individual proteins that are essential for replication. For MVM, NS2 appears to reprogram the host cell for efficient DNA amplification, single-strand progeny synthesis, capsid assembly, and virion export, though it seems to lack direct involvement in these processes. NS2 initially accumulates up to three times more quickly than NS1 in the early S-phase but is turned-over rapidly by a proteasome-mediated pathway. As the infectious cycle progresses, NS2 becomes less common as P38-driven transcription becomes more prominent. Another example is the nuclear phosphoprotein NP1 of bocaviruses, which, if not synthesized, results in non-viable progeny genomes.
As viral NS proteins accumulate, they commandeer host cell replication apparati, terminating host cell DNA synthesis and causing viral DNA amplification to begin. Interference with host DNA replication may be due to direct effects on host replication proteins that are not essential for viral replication, by extensive nicking of host DNA, or by the restructuring of the nucleus during viral infection. Early in infection, parvoviruses establish replication foci in the nucleus that are termed autonomous parvovirus-associated replication (APAR) bodies. NS1 co-localizes with replicating viral DNA in these structures with other cellular proteins necessary for viral DNA synthesis, while other complexes not required for replication are sequestered from APAR bodies. The exact manner by which proteins are included or excluded from APAR bodies is unclear and appears to vary from species to species and between cell types. As infection progresses, APAR microdomains begin to coalesce with other, formerly distinct, nuclear bodies to form progressively larger nuclear inclusions where viral replication and virion assembly occur. After S-phase begins, the host cell is forced to synthesize viral DNA and cannot leave S-phase.
MVM right-end origin
The right-end hairpin of MVM contains 248 nucleotides organized into a cruciform shape. This region is almost perfectly basepaired, with just three unpaired bases at the axis and a mismatched region positioned 20 nucleotides from the axis. A three nucleotide insertion, AGA or TCT, on one strand separates opposing pairs of NS1 binding sites, creating a 36 basepair-length palindrome that can assume an alternate cruciform configuration. This configuration is expected to destabilize the duplex, which facilitates its ability to function as a hinge. The mismatch of the unpaired bases, rather than the three-nucleotide sequence itself, may help to promote instability of duplex DNA.
Fully-duplex linear forms of the right-end hairpin sequence also function as NS1-dependent origins. For many parvoviral telomeres, however, only an initiator binding site next to the nick site is required for the origin function so that the minimal sequences required for nicking are less than 40 basepairs in length. For MVM, the minimal right-end origin is around 125 basepairs in length and includes most of the hairpin sequence because at least three recognition elements are involved: the nick site 5′-CTWWTCA-3′ (element 1), positioned seven nucleotides upstream from a duplex NS1-binding site (element 2) that is oriented to have the attached NS1 complex extending over the nick site, and a second NS1-binding site (element 3), which is adjacent to the hairpin axis.
The second binding site is over 100 basepairs away from the nick site but is required for NS1-mediated cleavage. In vivo, there is slight variation in the position of the nick, plus or minus one nucleotide, with one position preferred. During nicking, this site is likely exposed as a single strand and is potentially stabilized as a minimal stem-loop by the tetranucleotide inverted repeats to the sides of the site. Optimal forms of the NS1-binding site contain at least three tandem copies of the 5′-ACCA-3′ sequence. Modest alterations to these motifs only have a small effect on affinity, which suggests that each tetranucleotide motif is recognized by different molecules in the NS1 complex. The NS1-binding site that positions NS1 over the nick site in the right-end origin is a high affinity site.
With ATP, NS1 binds asymmetrically over the aforementioned sequence, protecting a region 41 basepairs in length from digestion. This footprint extends just five nucleotides beyond the 3′-end of the ACCA repeat but 22 nucleotides beyond the 5′-end so that the footprint ends 15 nucleotides beyond the nick site, placing NS1 in position to nick the origin. Nicking only occurs if the second, distant NS1-binding site is also present in the origin and the entire complex is activated by addition of HMG1.
In the absence of NS1, HMG1 binds the hairpin sequence independently, causing it to bend, without protecting any region from digestion. HMG1 can also directly bind to NS1 and mediates interactions between NS1 molecules bound to their recognition elements in the origin, so it is essential for formation of the cleavage complex. The ability of the axis region to reconfigure into a cruciform does not appear to be important in this process. Cleavage is dependent on the correct spacing of the elements of the origin, so additions and deletions can be lethal, whereas substitutions can be tolerated. Addition of HMG1 appears to only slightly adjust the sequences protected by NS1, but the conformation of the intervening DNA changes, folding into a double helical loop that extends about 30 basepairs through a guanine-rich element in the hairpin stem. Between this element and the nick site there are five thymidine residues included in the loop, and the site has a region to its side containing many alternating adenine and thymine residues, which likely increases flexibility. The creation of the loop likely allows the terminus to assume a specific 3-dimensional structure required to activate the nickase since origins that fail to reconfigure into a double-helical loop once HMG1 is added are not nicked.
Terminal resolution
Following nicking, a replication fork is established at the newly exposed 3′ nucleotide that proceeds to unfold and copy the right-end hairpin through a series of melting and reannealing reactions. This process begins once NS1 nicks the inboard end of the original hairpin. The terminal sequence is then copied in the opposite direction, which produces an inverted copy of the original sequence. The end result is a duplex extended-form terminus that contains two copies of the terminal sequence. While NS1 is required for this, it is unclear if unfolding is mediated by its helicase activity in front of the fork or by destabilization of the duplex following DNA binding at one of its 5′-(ACCA)-3′ recognition sites. This process is usually called terminal resolution but also hairpin transfer or hairpin resolution. Terminal resolution occurs with each round of replication, so progeny genomes contain an equal number of each terminal orientation. The two orientations are termed "flip" and "flop", and may be represented as R and r, or B and b, for the flip and flop of the right-end telomere and L and l, or A and a, for the flip and flop of the left-end telomere. Since parvoviral terminal palindromes are imperfect, it is easy to identify which orientation is which.
The extended-form duplex telomeres generated during terminal resolution are melted, mediated by NS1 with ATP hydrolysis, causing individual strands to fold back on themselves to create hairpin "rabbit ear" structures that have the flip and flop of the termini. This requires the NS1 helicase activity as well as its site-specific binding activity, the latter of which enables NS1 to bind to symmetrical copies of NS1-binding sites that surround the axis of the extended-form terminus.
Rabbit ear formation allows the 3′ nucleotide of the newly synthesized DNA strand to pair with an internal base, which repositions the replication fork in a strand-switching maneuver that primes synthesis of additional linear sequences. Switching from DNA synthesis to rabbit-ear formation at the end of terminal resolution may require different types of NS1 complexes. Alternatively, the NS1 complex may remain intact during this switch, being ready to start stand displacement synthesis following refolding into rabbit ears. After the replication fork is repositioned, replication continues toward the left end, using the newly synthesized DNA strand as a template.
At the left end of the genome, NS1 is probably required to unfold the hairpin. NS1 appears to be directly involved in melting-out and reconfiguring the resulting extended-form left-end duplexes into rabbit ear structures, though this reaction seems to be less efficient than at the right-end terminus. Dimeric and tetrameric concatemers of the genome are generated successively for MVM. In these concatemers, alternating unit-length genomes are fused through a palindromic junction in left-end to left-end and right-end to right-end orientations. In total, RHR results in coding sequences of the genome being copied twice as often as the termini. Both linear and hairpin configurations of the right-end telomere support initiation of RHR, so resolution of duplex right-end to right-end junctions can occur symmetrically on the basepaired duplex sequence or after this complex is melted and reconfigured into two hairpins. It is unclear which of these two reactions is more common since both appear to produce identical results.
For AAV, each telomere is 125 bases in length and capable folding into a T-shaped hairpin. AAV contains a Rep gene that encodes for four Rep proteins, two of which, Rep68 and Rep78, act as replication initiator proteins and fulfill the same functions, such the nickase and helicase activities, as NS1. They recognize and bind to a (GAGC) sequence in the stem region of the terminus and nick a site 20 bases away termed trs. The same process of terminal resolution as MVM is done for AAV, but at both ends. The other two Rep proteins, Rep52 and Rep40, are not involved in DNA replication but are implicated in synthesis of progeny. AAV replication is dependent on a helper virus that is either an adenovirus or a herpesvirus that coinfects the cell. In the absence of coinfection, the AAV genome is integrated into the host cell's DNA until coinfection occurs.
A general rule is that parvoviruses with identical termini, i.e. homotelomeric parvoviruses such as AAV and B19, replicate both ends by terminal resolution, generating equal numbers of flips and flops of each telomere. Parvoviruses that have different termini, i.e. heterotelomeric parvoviruses like MVM, replicate one end by terminal resolution and the other end by asymmetric junction resolution, which conserves a single-sequence orientation and requires different structural arrangements and cofactors to activate NS1's nickase. AAV DNA intermediates containing covalently linked sense and antisense strands yield genomic concatemers under denaturing conditions, indicating that AAV replication also synthesizes duplex concatemers that require some form of junction resolution.
MVM left-end origin
In negative-sense MVM genomes, the left-end hairpin is 121 nucleotides in length and exists in a single flip sequence orientation. This telomere is Y-shaped and contains small internal palindromes that fold into the "ears" of the Y, a duplex stem region 43 nucleotides in length that is interrupted by an asymmetric thymidine residue, and a mismatched "bubble" sequence in which the 5′-GAA-3′ sequence on the inboard arm is opposite of 5′-GA-3′ in the outboard strand. Sequences in this hairpin are involved in both replication and regulation of transcription. The elements involved in these two functions separate the two arms of the hairpin.
The left-end telomere of MVM, and likely of all heterotelomeric parvoviruses, cannot function as a replication origin in its hairpin configuration. Instead, a single origin on the lower strand is created when the hairpin is unfolded, extended, and copied to form a duplex basepaired sequence that spans adjacent genomes in the dimer RF. Within this structure, the sequence from the outboard arm that surrounds a GA/TC dinucleotide serves as an origin, OriL. The equivalent GAA/TTC sequence on the inboard arm that contains the bubble trinucleotide, called OriL, does not serve as an origin. The inboard arm and hairpin configuration of the terminus instead appear to function as upstream control elements for the viral transcriptional promoter P4. Additionally, the ability to segregate one arm from nicking appears essential for replication.
The minimal linear left-end origin is about 50 basepairs long and extends from two 5′-ACGT-3′ motifs, spaced five nucleotides apart at one end, to a position seven basepairs beyond the nick site. The bubble's GA sequence itself is relatively unimportant, but the space that it occupies is necessary for the origin to function. Within the origin, there are three recognition sequences: an NS1-binding site that orients the NS1 complex over the nick site 5′-CTWWTCA-3′, which is located 17 nucleotides downstream (toward the 3′-end), and the two ACGT motifs. These motifs bind a heterodimeric cellular factor called either parvovirus initiation factor (PIF) or glucocorticoid modulating element-binding protein (GMEB).
PIF is a site-specific DNA-binding heterodimeric complex that contains two subunits, p96 and p79, and functions as a transcription modulator in the host cell. It binds DNA via a KDWK fold and recognizes two ACGT half-sites. The spacing between these sites can vary significantly for PIF, from one to nine nucleotides, with an optimal spacing of six. PIF stabilizes the binding of NS1 on the active form of the left-end origin, OriL, but not on the inactive form, OriL, because the two complexes are able to establish contact over the bubble binucleotide. The left-end hairpin of all other species in the Protoparvovirus genus, of which MVM belongs, have bubble asymmetries and PIF-binding sites, though with slight variation in spacing. This suggests that they all share a similar origin segregation mechanism.
Asymmetric junction resolution
Due to the location of the active origin OriL in the dimer junction, synthesis of new copies of the left-end hairpin in the correct, i.e.flip, orientation is not straightforward since a replication fork moving from this site through the linear bridge structure should synthesize new DNA in the flop orientation. Instead, the left-hand MVM dimer junction is resolved asymmetrically in a process that creates a cruciform intermediate. This maneuver accomplishes two things: it allows synthesis of the new DNA in the correct sequence orientation, and it creates a structure that can be resolved by NS1. This "heterocruciform" model of synthesis suggests that resolution is driven by the NS1 helicase activity and depends on the inherent instability of the duplex palindrome, a property that allows it to switch between its linear and cruciform configurations.
NS1 initially introduces a single-strand nick in OriL in the B ("right") arm of the junction and becomes covalently attached to the DNA on the 5′ side of the nick, exposing a basepaired 3′ nucleotide. Two outcomes can then occur, depending on the speed with which a replication fork is assembled. If assembly is rapid, then while the junction is in its linear configuration, "read-through" synthesis copies the upper strand, which regenerates the duplex junction and displaces a positive-sense strand that feeds back into the replicative pool. This promotes MVM DNA amplification but does not lead to synthesis of new terminal sequences in the correct orientation or to junction resolution.
To create a resolvable structure, the initial nicking must be followed by melting and rearrangement of the dimer junction into a cruciform. This is driven by the 3′-to-5′ helicase activity of the 5′-linked NS1 complex. Once this cruciform extends to include sequences beyond the nick site, the exposed primer at the nick site in OriL undergoes template switching by annealing with its complement in the lower arm of the cruciform. If a fork assembles after this point, then the subsequent synthesis unfolds and copies the lower cruciform arm. This creates a heterocruciform intermediate that contains the newly synthesized telomere in the flip sequence orientation that is attached to the lower strand of the B arm. This modified junction is called MJ2.
The lower arm of MJ2 is an extended-form duplex palindrome that is essentially identical to those generated during terminal resolution. Once MJ2 is synthesized, the lower arm becomes susceptible to rabbit-ear formation. This repositions the 3′ nucleotide of the newly synthesized copy of the lower arm so that it pairs with inboard sequences on the junction's B arm to prime strand displacement synthesis. If a replication fork is created at this 3′ nucleotide, then the lower strand of the B arm is copied, creating an intermediate junction called MJ1 and progressively displacing the upper strand. This leads to the release of the newly synthesized B turn-around (B-ta) sequence. The residual cruciform, called δJ, is partially single-stranded at the upper part of the B arm and contains the intact upper strand of the junction paired to the lower strand of the A ("left") arm, with an intact copy of the left-end hairpin, ending in a 5′ NS1 complex. Since δJ carries the NS1 helicase, it is presumed to periodically alter configuration.
The next step is less certain but can be inferred based on what is known about the process thus far. The NS1 helicase is expected to create a dynamic structure in which the nick site in δJ in the normally inactive A side is temporarily but repeatedly exposed in a single-stranded form during duplex-to-hairpin rearrangements, which allows NS1 to engage the nick site in the origin OriL without the help of a cofactor. The nick would leave NS1 covalently attached to the positive-sense "B" strand of δJ and lead to the release of this strand. Nicking also leaves open a basepaired 3′ nucleotide on the "A" strand of δJ to prime DNA synthesis. If a replication fork is established here, then the A strand is unfolded and copied to create its duplex extended form.
When MVM genomes replicate in vivo, the aforementioned nick may not occur because both ends of the dimer replicative form contain an efficient number of right-end hairpin origins. Therefore, replication forks may progress back toward the dimer junction from the genome's right end, copying the top strand of the B arm before the final resolution nick. This bypasses dimer bridge resolution and recycles the top strand into a replicating duplex dimer pool. In a closely related virus, LuIII, the single-strand nick releases a positive-sense strand with its left-end hairpin in the flop orientation. Unlike MVM, LuIII packages strands of both sense with equal frequency. In the negative-sense strands, the left-end hairpins are all in the flip orientation, while in the positive-sense strands, there are an equal number of flip and flop orientations. Compared to MVM, LuIII contains a two-base insertion immediately 3′ of the nick site in the right origin, which impairs its efficiency. Because of this, the reduced efficiency of replication fork assembly in the genome's right end may favor single-strand nicking by giving it more time to occur.
Synthesis of progeny
Individual progeny genomes are excised from genomic replicative concatemers starting by introducing breaks in replication origins, usually by the replication initiator protein. This results in the establishment of new replication forks that replicate the telomeres in a combination of terminal resolution and junction resolution and displaces individual ssDNA genomes from the replicative molecule. At the end of this process, the telomeres are folded back inwards to form hairpins on excised genomes. The extended-form termini created during excision resemble the extended-form molecules prior to terminal resolution, so they can be melted out and refolded into rabbit ears for additional rounds of replication. Within an infected cell, numerous replicative concatemers are therefore able to arise.
Displacement of progeny ssDNA genomes either occurs: predominantly or exclusively during active DNA replication, or when cells are assembling viral particles. Displacement of single strands may therefore be associated with packaging viral DNA into capsids. Earlier research suggested that the preassembled viral particle may sequester the genome in a 5′-to-3′ direction as it is displaced from the fork, but more recent research suggests that packaging is performed in a 3′-to-5′ direction driven by the NS1 helicase using newly synthesized single strands.
It is not clear if these single strands are released into the nucleoplasm so that packaging complexes are physically separate from replication complexes or if the replication intermediates serve as both replication and packaging substrates. In the latter case, newly displaced progeny genomes would be kept in the replication complex via interactions between their 5′-linked NS1 molecules and NS1 or capsid proteins that are physically associated with replicating DNA. Genomes are inserted into the capsid via an entrance called a portal situated at one of the icosahedral 5-fold axes of the capsid, which is possibly opposite of the opening from which genomes are expelled early in the replication cycle.
Strand selection for encapsidation likely does not involve specific packaging signals but may be predictable by the Kinetic Hairpin Transfer (KHT) mathematical model, which explains the distribution of the strands and terminal conformations of packaged genomes in terms of the efficiency with which each terminus type can undergo reactions that allow it to be copied and reformed. In other words, the KHT model postulates that the relative efficiency with which two genomic termini are resolved and replicated determines the distribution of amplified replication intermediates created during infection and ultimately the efficiency with which ssDNAs of characteristic polarity and terminal orientations are excised, which will then be packaged with equal efficiency.
Preferential excision of particular genomes is only apparent during packaging. Therefore, among parvoviruses that package strands of one sense, replication appears to be biphasic. At early times, both sense strands are excised. This is followed by a switch in the replication mode that allows for exclusive synthesis of a single sense for packaging. A modified form of the KHT model, called the preferential strand displacement model, proposes that the aforementioned switch in replication is caused by the onset of packaging because the substrate for packaging is probably a newly displaced DNA molecule. For heterotelomeric parvoviruses, imbalance of origin firing leads to preferential displacement of negative sense strands from the right-end origin. The relative frequency of sense strands in packaged virions can therefore be used to infer the type of resolution mechanism used during excision.
Shortly after the start of S-phase, translation of viral mRNA leads to the accumulation of capsid proteins in the nucleus. These proteins form into oligomers that are assembled into intact empty capsids. After encapsidation, complete virions may be exported from the nucleus to the exterior of the cell before disintegration of the nucleus. Disruption of the host cell environment may also occur later on in infection. This results in cell lysis via necrosis or apoptosis, which releases virions to the outside of the cell.
Comparison to rolling circle replication
Many small replicons that have circular genomes such as circular ssDNA viruses and circular plasmids replicate via rolling circle replication (RCR), which is a unidirectional, strand displacement form of DNA replication similar to RHR. In RCR, successive rounds of replication, which proceeds in a loop around the genome, are initiated and terminated by site-specific single-strand nicks made by a replicon-encoded endonuclease, variously called the nickase, relaxase, mobilization protein (mob), transesterase, or replication protein (Rep). The replication initiator protein of parvoviruses is genetically related to these other endonucleases.
RCR initiator proteins contain three motifs considered to be important for replication. Two of these are retained within parvovirus initiator proteins: an HUHUUU cluster, which is presumed to bind to a ion required for nicking, and a YxxxK motif that contains the active-site tyrosine residue that attacks the phosphodiester bond of target DNA. In contrast to RCR initiator proteins, which can join together DNA strands, RHR initiator proteins have only vestigial traces of being able to perform ligation.
RCR begins when the initiator protein nicks a DNA strand at a specific sequence in the replication origin region. This is done through a transesterification reaction that forms a 5′-phosphate bond that connects the DNA to the active-site tyrosine and frees the 3′-end hydroxyl (3′-OH) adjacent to the nick site. The 3′-end is then used as a primer for the host DNA polymerase to begin replication while the initiator protein remains attached to the 5′-end of the "original" strand. After one loop of replication around the circular genome, the initiator protein returns to the nick site, i.e. the original initiator complex, while still attached to the parent strand and attacks the regenerated duplex nick site, or a nearby second site in some cases, by means of a topoisomerase-like nicking-joining reaction.
During the aforementioned reaction, the initiator protein cleaves a new nick site and is transferred across the analogous phosphodiester bond. It thereby becomes attached to the new 5′-end while ligating the 5′-end of the first strand to which it was originally attached to the 3′-end of the same strand. This second mechanism varies depending on the replicon. Some replicons such as the virus ΦX174 contain a second active tyrosine residue in the initiator protein. Others use the analogous active-site tyrosine in a second initiator protein that is present as part of a multimeric nickase complex.
This second nicking reaction may occur after one loop or successive loops may occur in which a concatemer containing multiple copies of the genome is created. The result of this nick is that displaced genomes become detached from the replicative molecule. These copies of the genome are ligated and may either be encapsidated into progeny capsids, provided they are monomeric, or converted to a covalently-closed double-stranded form by a host DNA polymerase for further replication. While RHR generally involves replication of both sense strands in a continuous process, RCR has complementary strand synthesis and genomic strand synthesis occur separately.
The strategies used in RHR to engage the nick site are also present in RCR. Most RCR origins are in the form of duplex DNA that has to be melted before nicking. RCR initiators accomplish this by binding to specific DNA-binding sequences in the origin next to the initiation site. The latter site is then melted in a process that consumes ATP and which is assisted by the ability of the separated strands to reconfigure into stem-loop structures. In these structures, the nick site is presented on an exposed loop. Like RHR initiator proteins, many RCR initiator proteins contain helicase activity, which allows them to melt the DNA prior to nicking and serve as the 3′-to-5′ helicase in the replication fork.
Notes
References
Bibliography
DNA replication
Molecular biology
Parvoviruses | Rolling hairpin replication | [
"Chemistry",
"Biology"
] | 9,366 | [
"Genetics techniques",
"DNA replication",
"Molecular genetics",
"Molecular biology",
"Biochemistry"
] |
66,387,234 | https://en.wikipedia.org/wiki/African%20Women%20in%20Mathematics%20Association | The African Women in Mathematics Association (AWMA) is a professional society whose mission is to promote mathematics to African women and girls, to support women's careers in mathematics, to create equal opportunity and equal treatment in the African mathematical community, and to create a meeting place for mathematical African women. The AWMA was founded in 2013. AWMA has approximately 300 members from over 30 countries and from all regions of Africa. It hosts events to encourage African girls' participation in mathematics.
History
In 1986, the African Mathematical Union founded the commission on women and mathematics (AMUCWMA). At the AMUCWMA's 2012 conference in Ouagadougou, which drew over 70 attendees, a panel on the state on women in mathematics in Africa was held. The panel's primary recommendation was to create an association for African female mathematicians. The AWUCWMA held another conference soon after in July 2013 in Cape Town. One of the primary objectives of the conference was to form an association for African women in mathematics. On July 19, 2013 at the conference, the African Women in Mathematics Association was officially formed. The primary objective was "the promotion of female mathematicians in Africa and the promotion of mathematics among girls and women in Africa".
The first AWMA conference was held in July 2015 in Naivasha, Kenya. The topic of the conference was Women in Mathematics for Social Change and Sustainable Livelihoods. Starting in October 2020, the association has hosted virtual seminars due to the COVID-19 pandemic. The first of these seminars was hosted by Aissa Wade on complex contact structures and Jacobi manifolds.
The AWMA has collaborated with the African Mathematical Union, Centre International de Mathématiques Pures et Appliquées, and European Women in Mathematics. They created their website in 2015, with assistance from the Women in Mathematics committee of the International Mathematical Union.
In coordination with other women's mathematics organizations, the AWMA celebrates women in mathematics during the May 12 Initiative. The date was chosen for Maryam Mirzakhani's birthday.
Organization
At the organization's formation, Marie Françoise Ouedraogo was elected president, Joséphine Guidy Wandja the vice president of Western Africa, Rebecca Walo Omana the Vice President of Central Africa, Schehrazad Selmane the Vice President of Northern Africa, Yirgalem Tsegaye the Vice President of Eastern Africa, and Sibusiso Moyo the Vice President of Southern Africa. The group is a nonprofit organization. Decisions are made by simple majority, and constitutional changes are made by 2/3 majority. A general meeting is held at least once every two years.
The organization lists its purpose as:
To encourage African women to take up and continue their studies in mathematics and to promote mathematics among women.
To support African women with or desiring careers in research in mathematics or Mathematics related fields.
To provide a meeting place for these women.
To foster international scientific communications among African women within and across fields in mathematics.
To promote equal opportunity and equal treatment of women and men in the African Mathematical community.
To increase access of African women to socio-economic benefits of mathematics.
To increase access of African women to grants.
To provide mentorship of African female students in primary, secondary and tertiary institutions both at the undergraduate and post graduate levels.
To promote participation of AWMA in the development of Africa.
To cooperate with groups and organizations with similar goals.
To promote cooperation and exchange of ideas in mathematics research and teaching of mathematics.
To stimulate communication between women in mathematics in Africa.
To organize research seminars and colloquia in mathematics in Africa.
To promote visits to Africa of eminent women and men in mathematics from other continents and organize inter-departmental visits and exchange visits.
To promote visits to African countries of eminent women and men in mathematics from Africa and African diaspora.
To seek and maintain contacts with other mathematics associations within and outside the Africa, provided that the objectives and purposes of such other associations are consistent with the objectives and purposes of the association.
To produce a research and information publication and any other publications deemed to be of value in the promotion of the above objectives.
To endow prizes and awards in mathematics.
To carry out any, do or transact any act, scheme or enterprise calculated to further the objectives of the Association.
See also
African Mathematical Union
History of mathematics in Africa
List of women in mathematics
Marie Françoise Ouedraogo
References
External links
African Women in Mathematics Association article in November 2020: European Women in Mathematics newsletter about the impact of COVID-19 on women mathematicians in Africa
Organizations for women in science and technology
Mathematical societies
Organizations established in 2013
Women in mathematics
Learned societies of Africa
African women | African Women in Mathematics Association | [
"Technology"
] | 944 | [
"Organizations for women in science and technology",
"Women in science and technology",
"Women in mathematics"
] |
66,387,301 | https://en.wikipedia.org/wiki/6-Chloronicotine | 6-Chloronicotine is a drug which acts as an agonist at neural nicotinic acetylcholine receptors. It substitutes for nicotine in animal studies with around twice the potency, and shows antinociceptive effects.
See also
ABT-418
Altinicline
Epibatidine
Tebanicline
References
Nicotinic agonists
Chloropyridines
Pyrrolidines | 6-Chloronicotine | [
"Chemistry"
] | 90 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
66,387,487 | https://en.wikipedia.org/wiki/Ellipsoid%20packing | In geometry, ellipsoid packing is the problem of arranging identical ellipsoid throughout three-dimensional space to fill the maximum possible fraction of space.
The currently densest known packing structure for ellipsoid has two candidates,
a simple monoclinic crystal with two ellipsoids of different orientations and
a square-triangle crystal containing 24 ellipsoids in the fundamental cell. The former monoclinic structure can reach a maximum packing fraction around for ellipsoids with maximal aspect ratios larger than . The packing fraction of the square-triangle crystal exceeds that of the monoclinic crystal for specific biaxial ellipsoids, like ellipsoids with ratios of the axes and . Any ellipsoids with aspect ratios larger than one can pack denser than spheres.
See also
Packing problems
Sphere packing
Tetrahedron packing
References
Packing problems | Ellipsoid packing | [
"Mathematics"
] | 181 | [
"Mathematical problems",
"Packing problems"
] |
66,390,572 | https://en.wikipedia.org/wiki/Monogenic%20function | A monogenic function is a complex function with a single finite derivative.
More precisely, a function defined on is called monogenic at , if exists and is finite, with:
Alternatively, it can be defined as the above limit having the same value for all paths. Functions can either have a single derivative (monogenic) or infinitely many derivatives (polygenic), with no intermediate cases. Furthermore, a function which is monogenic , is said to be monogenic on , and if is a domain of , then it is analytic as well (The notion of domains can also be generalized in a manner such that functions which are monogenic over non-connected subsets of , can show a weakened form of analyticity)
Monogenic term was coined by Cauchy.
References
Mathematical analysis
Functions and mappings | Monogenic function | [
"Mathematics"
] | 163 | [
"Mathematical analysis",
"Functions and mappings",
"Mathematical analysis stubs",
"Mathematical objects",
"Mathematical relations"
] |
66,390,800 | https://en.wikipedia.org/wiki/Guillotine%20partition | Guillotine partition is the process of partitioning a rectilinear polygon, possibly containing some holes, into rectangles, using only guillotine-cuts. A guillotine-cut (also called an edge-to-edge cut) is a straight bisecting line going from one edge of an existing polygon to the opposite edge, similarly to a paper guillotine.
Guillotine partition is particularly common in designing floorplans in microelectronics. An alternative term for a guillotine-partition in this context is a slicing partition or a slicing floorplan. Guillotine partitions are also the underlying structure of binary space partitions. There are various optimization problems related to guillotine partition, such as: minimizing the number of rectangles or the total length of cuts. These are variants of polygon partitioning problems, where the cuts are constrained to be guillotine cuts.
A related but different problem is guillotine cutting. In that problem, the original sheet is a plain rectangle without holes. The challenge comes from the fact that the dimensions of the small rectangles are fixed in advance. The optimization goals are usually to maximize the area of the produced rectangles or their value, or minimize the waste or the number of required sheets.
Computing a guillotine partition with a smallest edge-length
In the minimum edge-length rectangular-partition problem, the goal is to partition the original rectilinear polygon into rectangles, such that the total edge length is a minimum.
This problem can be solved in time even if the raw polygon has holes. The algorithm uses dynamic programming based on the following observation: there exists a minimum-length guillotine rectangular partition in which every maximal line segment contains a vertex of the boundary. Therefore, in each iteration, there are possible choices for the next guillotine cut, and there are altogether subproblems.
In the special case in which all holes are degenerate (single points), the minimum-length guillotine rectangular partition is at most 2 times the minimum-length rectangular partition. By a more careful analysis, it can be proved that the approximation factor is in fact at most 1.75. It is not known if the 1.75 is tight, but there is an instance in which the approximation factor is 1.5. Therefore, the guillotine partition provides a constant-factor approximation to the general problem, which is NP-hard.
These results can be extended to a d-dimensional box: a guillotine-partition with minimum edge-length can be found in time , and the total (d-1)-volume in the optimal guillotine-partition is at most times that of an optimal d-box partition.
Arora and Mitchell used the guillotine-partitioning technique to develop polynomial-time approximation schemes for various geometric optimization problems.
Number of guillotine partitions
Besides the computational problems, guillotine partitions were also studied from a combinatorial perspective. Suppose a given rectangle should be partitioned into smaller rectangles using guillotine cuts only. Obviously, there are infinitely many ways to do this, since even a single cut can take infinitely many values. However, the number of structurally-different guillotine partitions is bounded.
In two dimensions, there is an upper bound in attributed to Knuth. the exact number is the Schröder number.
In d dimensions, Ackerman, Barequet, Pinter and Romik give an exact summation formula, and prove that it is in . When d=2 this bound becomes .
Asinowski, Barequet, Mansour and Pinter also study the number of cut-equivalence classes of guillotine partitions.
Coloring guillotine partitions
A polychromatic coloring of a planar graph is a coloring of its vertices such that, in each face of the graph, each color appears at least once. Several researchers have tried to find the largest k such that a polychromatic k-coloring always exists. An important special case is when the graph represents a partition of a rectangle into rectangles.
Dinitz, Katz and Krakovski proved that there always exists a polychromatic 3-coloring.
Aigner-Horev, Katz, Krakovski and Loffler proved that, in the special sub-case in which the graph represents a guillotine partition, a strong polychromatic 4-coloring always exists.
Keszegh extended this result to d-dimensional guillotine partitions, and provided an efficient coloring algorithm.
Dimitrov, Aigner-Horev and Krakovski finally proved that there always exists a strong polychromatic 4-coloring.
See also
Binary space partitioning
References
Optimization algorithms and methods
Discrete geometry
Rectangular subdivisions | Guillotine partition | [
"Physics",
"Mathematics"
] | 997 | [
"Discrete mathematics",
"Tessellation",
"Discrete geometry",
"Rectangular subdivisions",
"Symmetry"
] |
66,390,815 | https://en.wikipedia.org/wiki/H3R17me2 | H3R17me2 is an epigenetic modification to the DNA packaging protein histone H3. It is a mark that indicates the di-methylation at the 17th arginine residue of the histone H3 protein. In epigenetics, arginine methylation of histones H3 and H4 is associated with a more accessible chromatin structure and thus higher levels of transcription. The existence of arginine demethylases that could reverse arginine methylation is controversial.
Nomenclature
The name of this modification indicates dimethylation of arginine 17 on histone H3 protein subunit:
Arginine
Arginine can be methylated once (monomethylated arginine) or twice (dimethylated arginine). Methylation of arginine residues is catalyzed by three different classes of protein arginine methyltransferases.
Arginine methylation affects the interactions between proteins and has been implicated in a variety of cellular processes, including protein trafficking, signal transduction, and transcriptional regulation.
Arginine methylation plays a major role in gene regulation because of the ability of the PRMTs to deposit key activating (histone H4R3me2, H3R2me2, H3R17me2, H3R26me2a) or repressive ( H3R8me2, H4R3me2) histone marks.
Histone modifications
THE genomic DNA of eukaryotic cells is wrapped around special protein molecules known as histones. The complexes formed by the looping of the DNA are known as chromatin.
Mechanism and function of modification
Methylation of H3R17 is mediated by CARM1 and is recruited to promoter upon gene activation along with acetyltransferases and activates transcription. When CARM1 is recruited to transcriptional promoters the histone H3 is methylated (H3R17me2 & H3R26me2). H3R17 dimethylation as a critical epigenetic mark in starvation-induced autophagy
Epigenetic implications
The post-translational modification of histone tails by either histone-modifying complexes or chromatin remodeling complexes is interpreted by the cell and leads to complex, combinatorial transcriptional output. It is thought that a histone code dictates the expression of genes by a complex interaction between the histones in a particular region. The current understanding and interpretation of histones comes from two large scale projects: ENCODE and the Epigenomic roadmap. The purpose of the epigenomic study was to investigate epigenetic changes across the entire genome. This led to chromatin states, which define genomic regions by grouping different proteins and/or histone modifications together.
Chromatin states were investigated in Drosophila cells by looking at the binding location of proteins in the genome. Use of ChIP-sequencing revealed regions in the genome characterized by different banding. Different developmental stages were profiled in Drosophila as well, an emphasis was placed on histone modification relevance. A look in to the data obtained led to the definition of chromatin states based on histone modifications. Certain modifications were mapped and enrichment was seen to localize in certain genomic regions.
The human genome is annotated with chromatin states. These annotated states can be used as new ways to annotate a genome independently of the underlying genome sequence. This independence from the DNA sequence enforces the epigenetic nature of histone modifications. Chromatin states are also useful in identifying regulatory elements that have no defined sequence, such as enhancers. This additional level of annotation allows for a deeper understanding of cell specific gene regulation.
Clinical significance
CARM1 knockout mice are smaller and die shortly after birth. CARM1 is required for the epigenetic maintenance of pluripotency and self-renewal, as it methylates H3R17 and H3R26 at core pluripotency genes such as Oct4, Sox2, and Nanog.
CARM1-mediated methylation of H3R17 is needed to establish and maintain the astroglial lineage. The absence of H3R17me2a downregulates miR-92a levels, and this miRNA is known to participate in neural development.
CARM1 was indirectly associated with diabetic retinopathy progression, as it and its associated H3R17me2a mark increased with high glucose, promoting apoptosis of the retinal pigment epithelial cells.
Methods
The histone mark H3K4me1 can be detected in a variety of ways:
1. Chromatin Immunoprecipitation Sequencing (ChIP-sequencing) measures the amount of DNA enrichment once bound to a targeted protein and immunoprecipitated. It results in good optimization and is used in vivo to reveal DNA-protein binding occurring in cells. ChIP-Seq can be used to identify and quantify various DNA fragments for different histone modifications along a genomic region.
2. Micrococcal Nuclease sequencing (MNase-seq) is used to investigate regions that are bound by well-positioned nucleosomes. Use of the micrococcal nuclease enzyme is employed to identify nucleosome positioning. Well-positioned nucleosomes are seen to have enrichment of sequences.
3. Assay for transposase accessible chromatin sequencing (ATAC-seq) is used to look in to regions that are nucleosome free (open chromatin). It uses hyperactive Tn5 transposon to highlight nucleosome localisation.
See also
Histone methylation
Histone methyltransferase
References
Epigenetics
Post-translational modification | H3R17me2 | [
"Chemistry"
] | 1,210 | [
"Post-translational modification",
"Gene expression",
"Biochemical reactions"
] |
61,390,972 | https://en.wikipedia.org/wiki/Onehunga%20Ironworks | The Onehunga Ironworks was a colonial-era iron smelting and rolling operation at Onehunga, on the Manukau Harbour, (now a suburb of Auckland, New Zealand). It was at one time claimed to be the largest ironworks in the Southern Hemisphere. It is significant, both as the first large scale attempt to exploit New Zealand's iron-sand by direct reduction, and as a precursor of the modern steel industry of New Zealand.
The ironworks was located adjacent to the original Onehunga railway station. It operated—but not continuously—from 1883 to around 1895. It was partially demolished around 1903 but its brick chimney and some of its other structures were still standing in the late 1960s.
Historical context
New Zealand's iron-sand resource
Vast deposits of iron-sand exist over 480 kilometres of the North Island's coast from Kaipara Harbour down to Whanganui. These iron-sand deposits are rich in the mineral titanomagnetite that originates as crystals within volcanic rock. As the rock is eroded, rivers carry the heavy grains of titanomagnetite to the coast. Currents, wind, and wave action then move the minerals along the coastline, concentrating them in dark-coloured sands on the sea floor, on beaches and in dunes.
Captain James Cook was probably the first European to record the 'black sands' of New Zealand's North Island, during his first voyage around New Zealand in 1769–70. In 1839, Ernst Dieffenbach, employed by the New Zealand Company to describe New Zealand's natural resources, noted the 'black titanic iron-sand' on beaches along the Taranaki coast.
Earlier smelting of iron-sand
Smelting of iron-sand has been carried out successfully in Japan for centuries, The Japanese method is a type of direct-reduction smelting. Smelting occurred in a Tatara furnace. That process is slow and makes only small batches of metal (known as Tamahagane) that is used in the making of high-quality steel weapons.
Although New Zealand's iron-sands are smelted today on a commercial scale, it took many years and many failed attempts before a successful process was developed that could smelt titanomagnetite iron-sand in commercially viable volumes. Before the establishment of the Onehunga Ironworks, other attempts had been made to smelt New Zealand iron-sands, but only "partial success was attained by smelting, in furnaces, bricks formed of the ore with calcareous clay and carbonaceous matter". The most notable of these earlier ventures was the New Zealand Titanic Steel and Iron Company, which was led by Edward Smith and had erected a blast furnace at Te Henui near New Plymouth.
Attempts to smelt iron-sands in blast furnaces—the conventional means used for other iron ores—failed for two main reasons; the fine sand grains blocked the flow of hot air through the furnace—something that could be overcome, to an extent, by binding the sand into 'bricks' as mentioned above—and carbon from the coke combined with titanium in the iron-sand to produce a thick pasty layer of compounds that blocked up the tap holes used to draw off the molten iron and slag.
History
First period of operation 1883–1887
John Chambers
It was the potential to exploit deposits of iron-sand near the heads of Manukau Harbour, which led to the establishment of the Onehunga Ironworks.
John Chambers had visited England and America in 1876 trying to interest ironmakers in the iron-sand, without success, but while in America he became aware of a process by which it was claimed wrought iron could be made from iron-sand. Chambers and an American, Guy H. Gardner of New York, jointly purchased the New Zealand patent rights of the furnace design patented in 1873, by Joel Wilson of Dover, New Jersey.
Wilson provided the services of William Henry Jones to come out to New Zealand to supervise the work. A full scale furnace using this design was erected at Onehunga during 1882. This first furnace was completed by early February 1883. A public demonstration of the furnace operation and smelting of iron-sand took place in early February 1883. The first billets of wrought iron smelted from iron-sand were made on 27 February 1883.
New Zealand Iron and Steel Company (Limited)
The initial success led to the formation of a company, New Zealand Iron and Steel Company (Limited), to expand the operation. The company had a capital of £200,000 made up of 40,000 shares of £5 each. Of these shares only 9,103 were sold to the public, resulting in a paid-up capital of £45,515.
The site on which the experimental furnace had been erected, 5 acres on the south-eastern side of Onehunga railway station, was purchased. This land had a water frontage onto the harbour—allowing raw material to be landed at the works—and a rail connection. Copious supplies of freshwater could be obtained from the Onehunga Springs. A lease—from where the iron-sand would be obtained—was taken over 6.5 miles of beach (some at South Head and some at the North Head of Manukau Harbour) and 1000 acres of land at the North Head.
It was planned to erect ten new furnaces and a rolling mill was ordered.
Wilson's process for iron-sand smelting
The smelting process was based on the method of direct reduction; iron-sand mixed with fine coal was heated to red-heat inside retorts and thereby reduced to 'sponge iron', which was then ‘puddled’ and worked to produce wrought iron. Joel Wilson's furnace design was ingenious, with the three different processes—'deoxidising' (direct reduction), 'balling' and 'puddling'—taking place within different parts of the same furnace structure and fired by the same fire grate.
The iron-sand was first washed and then concentrated magnetically, to remove silica sand.
A mixture of the concentrated iron-sand and the reducing agent (fine coal) was loaded into one of the multiple retorts of the smelting furnace, where this mixture resided for about 24-hours, during which it was heated by flue gases from the puddling furnace. —The multiple retorts in each furnace allowed an essentially 'batch' process to be operated more or less continuously, another ingenious feature of Wilson's design.—When a gate-valve in the base of any retort was opened, a sticky mass of hot, reduced iron-sand was transferred (by gravity) into the 'balling' section of the furnace; here it was heated for about half an hour—again by puddling furnace flue gases—until a ball of 'sponge iron', about 18-inches in diameter, was created. This ball was then rolled across into the 'puddling' section of the furnace. The conventional 19th-century iron-making process of puddling then took place, resulting in a ball-shaped piece of puddled iron. The puddled-iron ball was then removed from the furnace, and its processing thereafter was by conventional 19th-century iron-making techniques—shingling to create wrought iron, and hot-rolling to manufacture wrought-iron bars.
Difficulties and first closure
The works' reliance on the skill and knowledge of its American manager, William Henry Jones, became a serious problem, when in December 1883, he was charged with attempted murder. Jones was convicted and sentenced to 14 years gaol in April 1884.
After Jones' imprisonment, the company employed three other ironmasters—two subsequently leaving due to ill health—but none of them could replicate the extent of successful operation that Jones had achieved. Incomplete reduction of the iron-sand caused the resulting iron to have included, within its structure, grains of partially-reduced iron-sand, which made the iron hard or brittle.
Two of the ten planned new furnaces were in service by May 1885. These new furnaces were gas-fired, with the gas being produced by Wilson gas-producers that proved to be a problem. Gas quality was initially good but, by the time the furnace was up to temperature, either the heat fell away or explosions occurred, bringing work to a stop. These difficulties were never overcome.
Chambers was to claim later that the cost of production was too high at £9 per ton.
The plant managed to continue to operate but, by November 1886, the company had liabilities of £20,000 and all its paid-up capital had been expended. The shareholders were unwilling to contribute more capital. The assets were taken over by the mortgagee, and, by March 1887, the works had shut down.
Second period of operation 1887–1890
Onehunga Ironworks Company
The proprietors of the works were now Thomas and Samuel Morrin, who had large landholdings in the Waikato region. The venture was now known as the Onehunga Ironworks Company.
When the works shut down, rolling machinery had been bought by the New Zealand Iron and Steel Company, but had not been erected and put to work. It seems that there was also a quantity of wrought iron that had yet to be rolled into bars.
Enoch Hughes, expansion and the blast furnace
With the original manager, William Henry Jones—and his knowledge of iron-sand smelting—still in gaol, Enoch Hughes took over as manager of the Onehunga Ironworks on 22 August 1887, bringing with him some experienced workers from Australia.
Hughes came to New Zealand with many years experience in the iron industry—in England and Australia—but he had a chequered career while in Australia. Hughes recently had left the Eskbank Ironworks at Lithgow, under acrimonious circumstances and he had been blamed for the shortcomings of the blast furnace at the Fitzroy Iron Works at Mittagong, which he had erected while the works manager there in 1863–1864. However, Hughes did have a proven record in erecting and setting up iron rolling mills—he had erected the first iron rolling mill in Australia which commenced operation in June 1860—and it was in that role that he was first engaged at Onehunga.
Hughes was initially under contract to the proprietors, to erect the bar rolling mill and produce 120 tons of iron bars within four months. By late March 1888, the re-opened Onehunga Ironworks had made at least 400 tons of bars, using scrap iron and wrought iron that was already on hand at the works. Hughes operated the Onehunga works as a 'cooperative' with his workers, something he had done previously during his time at Lithgow.
By November 1888, the works had made 2000 tons of iron bar, but was finding the local demand for its bars inadequate. The proprietors then ordered a sheet mill and other equipment to make corrugated iron—the first such plant in New Zealand. At the end of June 1889, skilled workers from Pennsylvania were coming, to operate the sheet mill and commence production of corrugated iron.
Hughes had great confidence in his own abilities, including overcoming the daunting problems of smelting iron-sands. His interest in this went back to at least 1868.
The original plan was to mix the iron-sand with hematite ore (from Kamo near Whangārei) and smelt this mixture. By later in 1887, this had changed to making iron bars, using iron made from scrap iron with a 20% iron-sands admixture. Hughes expressed complete confidence that he could smelt the ironsands profitably, but it seems that he only ever did so experimentally and on a small scale. In June 1889, he said that the works had made iron entirely from iron-sand and in March 1890, such iron won first-class awards at the Dunedin Exhibition. Hughes position on the technology of iron-sand smelting seems to have been that direct reduction would not work at a commercially viable scale, and only a blast furnace —making pig-iron— could be successful. Hughes saw the solution as being to mix the iron-sand with other material such as hematite or clay-band ore.
In July 1889, a blast furnace, with a nominal capacity of 120 tons of iron per week, was under construction at Onehunga. The blast furnace was 45 feet tall, 16 feet external diameter and 11 feet at its largest internal diameter. The furnace was a hot-blast design. There was a steam winch to lift material to the top of the furnace, where there was a 26-foot diameter platform. The 40-horsepower blast engine and other parts of the furnace were from another (failed) iron-sand smelting venture, the New Zealand Titanic Steel and Iron Company, which was led by Edward Smith and had erected a blast furnace at Te Henui near New Plymouth. There were also two boilers and water pumps to keep the tuyeres cool.
The blast furnace made its first pig-iron, in July 1890. It seems that the iron was made with conventional iron ore, not iron-sand. However, in early September 1890, the furnace was 'allowed to cool', reportedly as a result of insufficient coal, due to industrial trouble at the mines. But, in fact, Hughes had built a furnace that could not achieve its purpose—to smelt iron-sand. Hughes should have been aware of the previous failure of the lengthy, earlier attempt at New Plymouth, but may have drawn the wrong conclusions from its partial success in making pig-iron; the outcome was predictable.
In late October 1890, Hughes was advocating the erection of another blast furnace at Kamo near Whangārei, where there was a hematite iron ore deposit with coal and limestone nearby. He was stating publicly that Onehunga would not be able to compete with a works at Kamo. No doubt his public stance would have annoyed the proprietors of the Onehunga Ironworks, who had just recently backed the now dormant Onehunga blast furnace. By December 1890, Hughes had been sacked by Onehunga and was suing the company, and, a little later, he was trying to dispose of his shares in it. He then returned to Australia.
Final years (1891–1895)
In 1891, the Onehunga Works was a much larger plant than it had been before Enoch Hughes's management—even before the blast furnace was erected, it was claimed to be the largest ironworks in the southern hemisphere—but it was no longer smelting iron ore, let alone iron-sand.
Other operations continued during 1891, but were subject to industrial trouble as the key 'puddling' workers went on strike for higher wages. Thomas J. Heskett became manager and conducted a trial smelting of 300 tons of limonite iron ore from Onekaka on Golden Bay, in the South Island. That ore and nearby coal deposits later became the resources used by the Onekaka Ironworks, established by Heskett's grandson, John Heskett, which operated between 1924 and 1935, using conventional blast furnace technology.
By June 1892, the works had reopened and was once again aiming to smelt iron-sand and so win a government bonus payment. These efforts involved Edward Smith as a consultant. By August 1893, a bonus had been paid, but critics claimed that little if any of the marketable iron involved was smelted from local ores; one describing the efforts as "a tin-pot experiment".
In January 1894, the works closed and its workforce was dismissed, only to reopen with a new workforce from Lithgow—some of whom had worked at Onehunga previously—who intended to operate the works as a 'cooperative'. The workers, from the Eskbank Ironworks at Lithgow, had left that works in 1894 with the blessing of their employer, William Sandford, because it was short of orders. It was Sandford who had first made enquiries to the owners of the Onehunga works, in an attempt to find work for his idle workforce. It seems that the Lithgow men made a living by rolling scrap iron into bars at Onehunga, but there was difficulty in obtaining sufficient scrap iron and work was carried on part-time only. At least some of these men drifted back to Lithgow, where prospects for work had improved.
By August 1895, the Onehunga Ironworks had shut down, it seems for the last time.
Demise and demolition
The works were sold in 1899, the buyer's intention being to relocate the rolling mills to Wellington. In 1903 there was an auction of equipment, iron and building materials—only part was sold—and it seems that the works may have been partially demolished at this time.
In the 1940s, the old ironworks site was occupied by Duroid Products (New Zealand) Limited.
The brick chimney and some structures of the Onehunga Ironworks were still standing in the late 1960s, but there is now no trace left of the old ironworks.
Legacy
Other attempts to exploit New Zealand's iron-sands as iron ore also failed, until a commercially viable process—now the basis of the modern steel industry of New Zealand—was developed by the Department of Scientific and Industrial Research, during the 1950s.
Like the original process used at Onehunga from 1883 to 1887, the modern process uses direct reduction of an iron-sand and coal mixture, but the resulting 'sponge iron' is now melted in an electric arc furnace to produce molten pig-iron that is then converted to steel by conventional means.
References
Industry in New Zealand
Iron and steel mills
History of Auckland
1883 establishments in New Zealand
1890s disestablishments in New Zealand
Ironworks | Onehunga Ironworks | [
"Chemistry"
] | 3,636 | [
"Iron and steel mills",
"Metallurgical facilities"
] |
61,391,308 | https://en.wikipedia.org/wiki/Alphasyllabic%20numeral%20system | Alphasyllabic numeral systems are a type of numeral systems, developed mostly in India starting around 500 AD. Based on various alphasyllabic scripts, in this type of numeral systems glyphs of the numerals are not abstract signs, but syllables of a script, and numerals are represented with these syllable-signs. On the basic principle of these systems, numeric values of the syllables are defined by the consonants and vowels which constitute them, so that consonants and vowels are - or are not in some systems in case of vowels - ordered to numeric values. While there are many hundreds of possible syllables in a script, and since in alphasyllabic numeral systems several syllables receive the same numeric value, so
the mapping is not injective.
Alphasyllabaries
The basic principle of the Indian alphasyllabaries is a set of 33 consonant-signs, which are combined with a set of about 20 diacritic marks that indicate vowels of the brahmi scripts, these produce a set of signs for syllables; unmarked consonant-signs denote the syllable with the inherent vowel ’a’.
Indian alphasyllabic numeration
Starting around 500 AD, Indian astronomers and astrologers began to use this new principle for numeration with assigning numeral values to the phonetic signs of various Indian alphasyllabic scripts – the brahmi scripts. Earlier 20th-century scholars supposed that the Indian grammarian Pāṇini used alphasyllabic numerals already in the 7th century BC. Since there is no direct evidence for any alphasyllabic numeration in India until about 510 AD, recently this theory is not supported.
These systems, known collectively as varnasankhya systems, were considered to be distinct from other Indian systems – i.e. brahmi or kharosthi numerals - that had abstract numeral-signs. Alike the alphabetic systems of Europe and the Middle East, these systems used phonetic signs of a script for numeration, but they were more flexible than those. Three significant systems of them: Āryabhaṭa numeration, katapayadi system, and the aksharapalli numerals.
Alphasyllabic numeration are very important for understanding Indian astronomy, astrology, and numerology, since Indian astronomical texts were written in Sanskrit verse, which had strict metrical form. These systems had the advantage of being able to give any word a numerical value, and to find many words corresponding to one given number. This made possible the construction of various mnemonics to aid scholars and students, and would have served a prosodic function.
Structure
Structure of the Indian alphasyllabic numeration systems differs basically from one another. Though in each of the systems consonants and vowels are ordered to numeric values, thereby each syllable has a numeric value, but on the base of each system's own rules. In various systems the V, CV, CCV syllables receive different values, and the methods, how the numbers are represented by these syllables, are quite different.
Āryabhaṭa numeration system operates on the additive principle, so that the number's value, which is represented in it, is computed as the sum of each syllable's numeric value. In his mapping, the consonants are ordered from 1 to 25, then by tens from 30 to 100. Each successive vowel is ordered to the different exponent of 100. In Āryabhaṭa numeration’s the diacritic signs, which mark vowels, multiply the value of the syllable’s consonant by the given power of 100. Direction of his script is right to left, which reflects the order of the Sanskrit lexical numerals.
In katapayadi system, syllables have the numeric values only from 0 to 9. To each V, CV and CCV syllable is given a value between 0 and 9. In this way each number between 0 and 9 are ordered to several syllables. Unlike Aryabhata's system, changing the vowel in the syllable doesn’t change the syllable’s numerical value. The number’s value, which is represented in this way, is given as positional number with one syllable on each position. Direction of this script is right to left.
In aksharapalli system, syllables were assigned the numerical values 1–9, 10–90, but never as high as 1000. According to S. Chrisomalis there was never a single regular system for correlating signs with numeral values in this system. It was used widely for paginating books, aksharapalli numerals were written in the margins from top to bottom.
Systems
Āryabhaṭa numeration
Katapayadi system
Aksharapalli
Tuubhyara
References
Sources
Georges Ifrah: The Universal History of Numbers. From Prehistory to the Invention of the Computer. John Wiley & Sons, New York, 2000, .
See also
Alphabetic numeral system
Bhutasamkhya system
Numeral systems
Indian mathematics | Alphasyllabic numeral system | [
"Mathematics"
] | 1,036 | [
"Numeral systems",
"Mathematical objects",
"Numbers"
] |
61,392,110 | https://en.wikipedia.org/wiki/Eva%20Harth | Eva M. Harth FRSC is a German-American polymer scientist and researcher, and a fellow of both the Royal Society of Chemistry and the American Chemical Society. She is a full professor at the University of Houston and director of the Welch Center for Excellence in Polymer Chemistry.
Education
She received her undergraduate degree from the University of Bonn (BS) and her graduate degrees at the University of Zurich (MS) and the Max Planck Institute for Polymer Research (PhD). Under the guidance of Klaus Müllen, Harth completed her PhD on fullerene-based polymers with her thesis, Synthesis and properties of new fullerene adducts and fullerene-containing polymers, in 1998.
Career and research
Early career
Eva Harth moved to the United States as a National Science Foundation postdoctoral fellow to the IBM Almaden Research Center. She worked with chemist Craig Hawker on polymeric nanoparticles and nitroxide polymerization for two years and then moved to a start-up company, XenoPort, Inc.
Vanderbilt University
In 2004, she started at Vanderbilt University as an assistant professor, was promoted to associate professor in 2011, and served three years as director and DGS of the Interdisciplinary Materials Science Graduate Program (IMS).
During her time at Vanderbilt, she developed a nanosponge delivery system that is licensed by a start-up company. The biodegradable nanoparticle, composed of crosslinked polyester, contains tiny cavities that can store drug molecules. The nanoparticle breaks down in the body, releasing the drug in a predictable fashion, and can be further functionalized with a targeting peptide to favor drug delivery to cancerous cells.
University of Houston
Harth moved to the University of Houston as a full professor in 2017, where her research expanded into the area of metal-organic chemistry. In 2018, the group developed the metal-insertion light-initiated radical (MILRad) polymerization.
Her current research group focuses on incorporating functional groups into polyolefins, combining polymerization methodologies to design novel polymer structures containing polyolefins. The group has a long-standing interest in biomedical materials and technologies to increase the therapeutic function of synthetic and biological substances.
In 2022, the group developed Polyolefin Active Ester Exchange (PACE) process to give access to polyolefin block copolymers containing vinylic, acrylic and polyester and polyamide segments.
Editorial and advisory work
In 2017, Harth received a Gutenberg Chair Award from the University of Strasbourg and was admitted as a Fellow of the Royal Society of Chemistry. From 2009–2018, she served as an associate editor for Polymer Chemistry, a journal of the RSC.
She is a member of the advisory board of Polymer Chemistry and is an associate editor of the European Polymer Journal.
Awards and honors
2007 NSF Career Award
2017 Gutenberg Chair
2017 Fellow of the Royal Society of Chemistry
2021 Fellow of the American Chemical Society
References
Notes
Polymer scientists and engineers
Living people
University of Bonn alumni
University of Zurich alumni
University of Houston faculty
Vanderbilt University faculty
German women chemists
21st-century German chemists
21st-century women scientists
Fellows of the Royal Society of Chemistry
21st-century German women
Fellows of the American Chemical Society
1968 births | Eva Harth | [
"Chemistry",
"Materials_science"
] | 655 | [
"Polymer scientists and engineers",
"Physical chemists",
"Polymer chemistry"
] |
61,393,318 | https://en.wikipedia.org/wiki/Mutanome | The mutanome is the entirety of somatic cancer mutations in an individual tumor.
Description
Carcinogenesis is largely driven by changes in the DNA sequence of the genomes of cancer cells. This process leads to a unique repertoire of mutations (′the mutanome′) in every patient's tumor. The mutanome encodes peptides that can be targets for T cells, which play a central role in the immune response.
A description of individual mutanomes of human tumors has been made feasible by the introduction of Next Generation Sequencing Technology (NGS). Cancer mutanomes can be defined by comparing exome sequencing data obtained by NGS of individual healthy tissue with sequences from tumor-derived nucleic acids. As the vast majority of cancer-associated mutations are patient specific, shared mutations are rare, even within the same type of cancer.
Neoantigens and neoepitopes
The mutanome encodes a pattern of tumor-specific mutated peptides referred to as neoantigens or m-peptides. Neoantigens are products of mutations that first occur in the course of cancer development. Each and every tumor has its own unique neoantigenic pattern, and even within the same type of cancer, only a small percentage of neoantigens are shared.
Neoantigens are presented on major histocompatibility complex (MHC) molecules of tumor cells. The antigenic determinants of neoantigens – neoepitopes – are recognized by the immune system as a target for T cells, thus triggering immune responses against cancer.
A neoepitope is an epitope the immune system has not encountered before. Therefore, it is not subject to tolerance mechanisms of the immune system. Since the mutated gene product is only expressed in tumors, but not on healthy cells, neoepitopes may evoke vigorous T cell response.
Mutanome immunotherapy
The vast majority of cancer mutations are unique to the individual patient, and a significant portion of mutations (21-45%) are immunogenic. Therefore, the patients' individual mutanome and the neoepitopes are used as the basis for a novel strategy against cancer, which is referred to as individualized cancer immunotherapy. Cancer immunotherapy uses the body's own immune defense system and is based on the recognition by cytotoxic and helper T cells with antitumor activity.
Mutanome-specific vaccines
Strategies to immunotherapeutically address the individual mutanome are currently under investigation. Ongoing mutanome cancer vaccine trials use synthetic peptides and antigen-encoding DNA or RNA as formats. For an individualized treatment, neoepitopes that are thought to elicit a strong immune response are selected out of the patient's mutanome.
An increasingly explored concept for individualized cancer immunotherapy is the treatment of a patient with immunogenic mRNA vaccines for a given patient's individual cancer mutanome (IVAC - Individualized Vaccine Against Cancer). The IVAC concept is based on decoding the individual mutanome by NGS and on-demand mRNA manufacturing for use in single patients to produce therapeutic vaccines against cancer.
Since 2016, the IVAC concept has been developed as Individualized Neoantigen Specific Therapy (iNeST).
The process of NSG based cancer mutanome mapping, target selection, prioritization approaches, synthetic mRNA vaccine manufacturing and delivery is also referred to as MERIT (mutanome engineered RNA immunotherapy). By vaccination with the synthetic mRNA, which contains the blueprint of a mutant tumor peptide, T lymphocytes are activated against the tumor.
References
External links
The MERIT (Mutanome Engineered RNA Immuno-Therapy) project – European Union funded Initiative
GAPVAC (Glioma Actively Personalized Vaccine Consortium) – European Union funded Initiative
Medical genetics
Biotechnology
Applied genetics
Genomics
Vaccines
Cancer vaccines | Mutanome | [
"Biology"
] | 817 | [
"nan",
"Vaccination",
"Vaccines",
"Biotechnology"
] |
61,396,323 | https://en.wikipedia.org/wiki/Ro-Pat-In%20Corporation | Ro-Pat-In Corporation (ElectRo-Patent-Instruments) was founded by Adolph Rickenbacher and George Beauchamp in 1931 to manufacture and distribute electrically amplified musical instruments. Beauchamp designed the instruments, assisted by Paul Barth and Harry Watson from National String Instrument Corporation. Ro-Pat-In would eventually develop into Rickenbacher and ultimately: Rickenbacker a leader manufacturer in musical instruments, who is still active today. Early examples from Ro-Pat-In bear the brand name Electro.
Early history
At the end of 1931, Beauchamp, Barth, Rickenbacher and several other individuals banded together and formed the Ro-Pat-In Corporation (elektRO-PATent-INstruments) to manufacture and distribute electrically amplified musical instruments, with an emphasis on their newly developed A-25 Hawaiian Guitar, often referred to as the "fry-pan" lap-steel electric guitar as well as an Electric Spanish (standard) model and companion amplifiers. In the summer of 1932, Ro-Pat-In began to manufacture cast aluminum production versions of the Fry-Pan as well as a lesser number of standard Spanish Electrics also known as "Electro-Spanish" models, built from wooden bodies similar to those made in Chicago for the National Company. These instruments constitute the origin of the electric guitar by virtue of their string-driven electro-magnetic pick-ups. In 1933 the Ro-Pat-In company's name was changed to Electro String Instrument Corporation and its instruments labeled simply as "Electro". In 1934 the name of Rickenbacker" was added in honor of the company's principal partner, Adolph Rickenbacher.
References
American musical instrument makers
Electrical equipment manufacturers | Ro-Pat-In Corporation | [
"Engineering"
] | 341 | [
"Electrical engineering organizations",
"Electrical equipment manufacturers"
] |
61,400,305 | https://en.wikipedia.org/wiki/Jane%20Osbourn | Jane Osbourn, OBE, is a scientist and former chair of the UK BioIndustry Association.
A Natural Sciences graduate of Queens' College, Cambridge, Osbourn completed several post-graduate qualifications before moving into industry at Cambridge Antibody Technology, that became MedImmune and AstraZeneca.
In the Queen's Birthday Honours list of 2019, Osbourn was awarded the Order of the British Empire medal for services to "Human Monoclonal Antibody Drug Research and Development and Biotechnology".
Early life
Osbourn was born in Bingley, West Yorkshire, and attended Bingley Grammar School. She is married to John Richer, Professor of Physics at the Cavendish Laboratory, Cambridge.
She is the sister of Professor Anne Osbourn FRS who investigates plant natural product biosynthesis.
Academic career
Osbourn went on to study at the Queens' College, Cambridge, where she obtained a 1st class degree in Natural Sciences (Biochemistry). She was recognised in 1986 for playing netball at Queens, and was awarded both a third year Foundation Scholarship and The Henry Mosseri prize.
She went on to complete a PhD degree at the John Innes Centre for Plant Science Research in Norwich, which resulted in the publication of Evidence that nucleocapsid disassembly and a later step in virus replication are inhibited in transgenic tobacco protoplasts expressing TMV coat protein. Following this, she completed a post-doctoral position at Rutgers University, New Jersey, United States, undertaking research directed towards clarification of the sequence elements responsible for the translational enhancement effect conferred by the 5' untranslated region of Tobacco Mosaic Virus known as omega.
Osbourn then moved into medical research through a British Heart Foundation Post-Doctoral Fellowship at the Department of Medicine at Addenbrooke's Hospital in Cambridge.
Career in industry
In 1993 she moved to a small, Cambridge-based, start-up biotechnology company called Cambridge Antibody Technology. CAT, as it was called, would pioneer the use of Phage Display technology that ultimately discovered important drugs such as Humira.
She was the key author of several scientific papers, including Human Antibodies with Sub-nanomolar Affinities Isolated from a Large Non-immunized Phage Display Library, Nature Biotechnology, 1996 and Human Antibodies by Design, Nature Biotechnology, 1998. She is co-author of several others pertaining to antibody discovery and development:
A Biparatopic HER2-Targeting Antibody-Drug Conjugate Induces Tumor Regression in Primary Models Refractory to or Ineligible for HER2-Targeted Therapy, Cancer Cell, 2019
Engineering of a GLP-1 analogue peptide/anti-PCSK9 antibody fusion for type 2 diabetes treatment, Sci Rep, 2018
A novel in vivo method for isolating antibodies from a phage display library by neuronal retrograde transport selectively yields antibodies against p75(NTR.), MAbs, 2013
Applications of ribosome display to antibody drug discovery, Expert Opin Biol Ther, 2015
Signal amplification in flow cytometry using biotin tyramine, Cytometry, 1999
Aquaporin-1 is expressed by vascular smooth muscle cells and mediates rapid water transport across vascular cell membranes, J Vasc Res, 1999
Directed selection of MIP-1 alpha neutralizing CCR5 antibodies from a phage display human antibody library, Nat Biotechnology, 1999
Pathfinder selection: in situ isolation of novel antibodies, Immunotechnology, 1998
Generation of a panel of related human scFv antibodies with high affinities for human CEA, Immunotechnology, 1996
Osbourn is listed as an inventor on several patents, which are (in chronological order):
EP0865492B1 - Specific binding members for human carcinoembryonic antigen, materials and methods
EP0906571 - Labelling and selection of molecules
US5994519A - Labelling and selection of molecules
EP1353180B1 - Labelling and selection of molecules
US7074557 - Ribosome Display
EP1268766 - Improvements to Ribosome Display
WO2001075097A2 - Improvements to Ribosome Display
Osbourn also created a technique to assist with the discovery of proximity-guided selection of antibodies, so called Proximol.
CAT was acquired by AstraZeneca in 2006 and in the following year was merged with a US-based company called MedImmune to form AstraZeneca’s global biologics R&D arm. During this time Osbourn began to speak about opportunities for diversity in science.
In 2013, AstraZeneca announced its decision to relocate its headquarters to Cambridge, UK. Jonathan Burroughs, of Creative Places, wrote in 2015 that Osbourn had an influence over this decision.
In February 2019, it was announced that Osbourn would be leaving AstraZeneca. Since November 2019, Osbourn has been Chief Scientific Office of antibody therapeutics discovery company Alchemab Therapeutics.
Recognition
Her early interest in science has grown into a passion for science education, supporting and championing life science education programmes and she is established as an advisor and mentor to many young researchers in the life science sector. She has been acknowledged by a number of different pharmaceutical media groups for these qualities.
She has been recognised in two BioBeat Movers and Shakers lists - BioBeat 50 Movers and Shakers in BioBusiness 2014 and 2016. BioBeat is an organisation that connects entrepreneurs with the leaders in biotech.
In 2016 she was recognised in the PharmaVoice 100 researchers and scientists. PharmaVOICE is a resource for life-sciences executives and other healthcare-service related professionals
In 2016, Fierce Pharma’s “Fierce Women in Biopharma” recognised her as one of 15 women in the global industry noteworthy for their leadership, providing mentorship and helping increase opportunities for women in science. FierceBiotech and its family of publications provide end-to-end coverage of biotech and medtech, from pre-clinical science through clinical testing and regulatory approval.
In 2014 Osbourn was elected to join the board of the BioIndustry Association, becoming Chair in 2016; and in this role she has been working to support the development of the biotechnology sector in the UK. She also does this through her roles as a Director of Babraham Bioscience Technologies and as a Director of Cambridge Enterprise, the technology transfer organisation for University of Cambridge.
Osbourn has presented at a number of parliamentary Select Committees. At the Business, Innovation and Skills Committee, on Tuesday 13 May 2014, she gave evidence on behalf of AstraZeneca as it faced a potential takeover from Pfizer.
On 1 July that year, Osbourn gave evidence to the Science and Technology Select Committee: Priorities for Scientific Research.
Osbourn has also has previously served as a Member of the UK Medical Research Council Industry Grant Award Assessment Panel.
In 2018 the Nobel Prize for Chemistry was awarded jointly to Sir Greg Winter, George Smith and Frances Arnold. Winter received his award for the phage display of peptides and antibodies. Sir Greg and David Chiswell had founded Cambridge Antibody Technology to exploit this science. Osbourn says of this time, "There was a cohort of really able intellect in Cambridge – in CAT and other companies, in the MRC LMB and in the University – and what happened was a condensation of that focus… Once we decided to make phage display work, we set some really tough goals and then just got on with it." To recognise Jane’s contribution to the prize, she, along with David Chiswell and John McCafferty, accompanied Sir Greg to the Nobel ceremony.
On 7 June 2019 she was awarded an OBE for services to Human Monoclonal Antibody Drug Research and Development and Biotechnology. CEO of AstraZeneca, Pascal Soriot, said of the award "On behalf of AstraZeneca, I am delighted to congratulate Dr Jane Osbourn for her award of an OBE in recognition of her services to human monoclonal antibody drug research and development and biotechnology. This well-deserved honour reflects her contribution to biopharmaceutical science over more than 25 years, from Cambridge Antibody Technology to AstraZeneca and MedImmune. Jane’s leadership in UK life sciences includes championing the biotech sector through her position as chair of the BIA and contributing to the growth of the UK’s scientific ecosystem. I would also like to recognise her authentic commitment to building skills through STEM and education outreach, in particular for women in science".
References
Biotechnologists
Members of the Order of the British Empire
Living people
Year of birth missing (living people)
Alumni of Queens' College, Cambridge
Women biotechnologists
21st-century women scientists | Jane Osbourn | [
"Biology"
] | 1,816 | [
"Biotechnologists",
"Women biotechnologists"
] |
61,400,489 | https://en.wikipedia.org/wiki/Phaeton%20complex | The Phaeton complex is a psychological condition described by Maryse Choisy as a "painful combination of thoughts and emotions caused by the absence, loss, coldness, or traumatizing behavior of one or both parents, resulting in frustration and aggression".
The theory was devised by Lucille Iremonger, who in 1970 studied the 24 British prime ministers who held office from 1809 to 1940, and found that 62% of these men had lost one or both parents by age 15, compared to a national average of 10-15% in those times. Hugh Berrington expanded on the theory in 1974, finding sufferers of the Phaeton complex to be less sociable, flexible or tolerant, instead being ambitious, vain, sensitive, lonely and shy. Micha Popper, though, disputes that an unhappy childhood always leads to obsessive urges, citing Winston Churchill as an example where childhood unhappiness had positive results.
The name derives from the Greek myth of Phaeton, a child of the sun god, who demands to drive his father's chariot and in doing so, falls to earth and scorches the Sahara Desert.
Examples
Neville Chamberlain, UK prime minister 1937–40, having lost his mother by age six, is said to have displayed 'all the characteristics of the damaged Phaeton - immature, sensitive, cold, secretive and depressed' when in office, according to Harry Davis.
Zulfikar Ali Bhutto is described by Shamim Ahmad as a neglected child, 'having a sense of insecurity that drove him to prove himself worthy'.
In a discussion of the Phaeton complex, Tom McTague lists Boris Johnson, Theresa May, Bill Clinton and Tony Blair as examples of ambitious, isolated, detached politicians who suffered a 'deprivation of love' in childhood.
See also
Complex (psychology)
Ideocracy
Napoleon complex
References
Complex (psychology)
Power (social and political) theories
Mental health
Narcissism | Phaeton complex | [
"Biology"
] | 401 | [
"Behavior",
"Narcissism",
"Human behavior"
] |
69,270,951 | https://en.wikipedia.org/wiki/Neural%20synchrony | Neural synchrony is the correlation of brain activity across two or more people over time. In social and affective neuroscience, neural synchrony specifically refers to the degree of similarity between the spatio-temporal neural fluctuations of multiple people. This phenomenon represents the convergence and coupling of different people's neurocognitive systems, and it is thought to be the neural substrate for many forms of interpersonal dynamics and shared experiences. Some research also refers to neural synchrony as inter-brain synchrony, brain-to-brain coupling, inter-subject correlation, between-brain connectivity, or neural coupling. In the current literature, neural synchrony is notably distinct from intra-brain synchrony—sometimes also called neural synchrony—which denotes the coupling of activity across regions of a single individual's brain.
Neural synchrony approaches represent an important theoretical and methodological contribution to the field. Since its conception, studies of neural synchrony have helped elucidate the mechanisms underlying social phenomena, including communication, narrative processing, coordination, and cooperation. By emphasizing the social dynamics of the brain, this area of research has played a critical role in making neuroscience more attuned to people's social proclivities—a perspective that is often lost on individual-level approaches to understanding the brain.
History
Motivation
Driven by the desire to understand the social nature of the human brain, the study of neural synchrony stems from social cognition, a subfield of psychology that explores how we understand and interact with other people through processes like mentalization or theory of mind. Given that it relies on measuring brain activity, neural synchrony also has its roots in cognitive neuroscience.
Despite the growth of social cognition and cognitive neuroscience prior to the early 2000s, research into the brain neglected interpersonal processes, focusing mostly on the neural mechanisms of individuals' behaviors. Furthermore, neuroscience research that did probe social questions only investigated how social processes affect neural dynamics in a single brain. Considering that researchers clearly recognized how interpersonal interaction was fundamental to human cognition, the paucity of social and multi-brain neuroscience research represented a tension in the field. In response to the discrepancy between the complexity of social interaction and the single-brain focus of cognitive neuroscience, researchers called for a multi-person, interaction-oriented approach to understanding the brain.
Early history
In 2002, the American neuroscientist P. Read Montague articulated the need to examine the neural activity of multiple individuals at one time. To this point, Montague and his colleagues wrote, "Studying social interactions by scanning the brain of just one person is analogous to studying synapses while observing either the presynaptic neuron or the postsynaptic neuron, but never both simultaneously." They performed the first brain scan of more than one person by using functional magnetic resonance imaging (fMRI) to take simultaneous recordings of two people engaged in a simple deception game. While this study marked the first example of multi-brain neuroimaging, in 2005, King-Casas and others combined neuroimaging with an economic exchange game to conduct the first study that directly compared neural activity between pairs of subjects. Since then, multi-brain imaging studies have grown in popularity, leading to the formation of preliminary neural synchrony frameworks.
Early conceptualizations of neural synchrony, mostly from the Hasson Lab at Princeton University, were motivated by models of stimulus-to-brain coupling. In these models, aspects of the physical environment emit mechanical, chemical, and electromagnetic signals, which the brain receives and translates into electrical impulses that guide our actions and allow us to understand the world. Researchers presumed that the synchronization of neural activity between two brains should leverage the same system that binds one's neural activity to environmental stimuli. If the stimulus is another person, then the perceptual system of one brain may couple with the behaviors or emotions of the other person, causing "vicarious activations" that manifest as synchronized neural responses across perceiver and agent. According to the theory, this process also occurs through more complex, synergistic interactions, especially when people communicate and convey meaning.
Further development
Over the last two decades, neural synchrony has become an increasingly common topic of study in social and affective neuroscience research, spurring conceptual and methodological development. Along with an emphasis on ecologically valid, naturalistic experimental designs, the focus on multi-brain neuroscience studies has increased researchers' ability to explore neural synchrony in social contexts. As a result, conceptualizations of neural synchrony have been expanded to incorporate a wider range of ideas, though it is often viewed as a neural correlate for two or more people's shared experiences. Studies now involve a variety of social processes, with applications spanning simple motor synchronization to classroom learning.
Notable methodological advancements have come from the evolution of multi-brain imaging techniques beyond fMRI, especially magnetoencephalography/electroencephalography (MEG/EEG) and functional near-infrared spectroscopy (fNIRS)—methods which afford more socially interactive experimental designs. These technologies are also complemented by comprehensive data processing techniques that are useful in multi-brain analyses, such as Granger causality or Phase Locking Value (PLV).
As a progressively paradigmatic approach in social and affective neuroscience, neural synchrony undergirds the field's search for the brain basis of social interaction.
A 2022 study by the University of Helsinki measured brain synchronization among players during cooperative online video gaming.
Methods
Hyperscanning
The study of neural synchrony is predicated on advanced neuroimaging methods, particularly hyperscanning. Coined in 2002 by Montague et al., hyperscanning refers to the method of simultaneously measuring the hemodynamic or neuroelectric responses of two or more brains as they engage with the same task or stimulus. The ability to record time-locked activity from multiple brains makes hyperscanning conducive to exploring the variation in activity across brains. It also allows experimenters to examine various aspects of neural recordings in naturalistic scenarios, from low-level stimulus processing to high-level social cognition. For these reasons, hyperscanning has helped foster a systematic investigation of interpersonal dynamics at the level of the brain.
Though hyperscanning has become the most common imaging technique for studying neural synchrony, researchers do not necessarily need to scan brains simultaneously. Sometimes referred to as off-line measurement, or "pseudo-hyperscanning"; this alternative approach follows the same basic premise as hyperscanning, except that participants' brain activity is recorded one at a time. Data from different scans of isolated participants are then analyzed to compare functional similarities during identical tasks or stimuli.
Imaging techniques
Hyperscanning and off-line scanning methods can be achieved through common noninvasive hemodynamic or neuroelectric brain imaging techniques. A review of neural synchrony hyperscanning studies showed that the most prevalent methods are EEG, fNIRS, and fMRI, which account for 47%, 35%, and 17% of studies, respectively. Each technique offers unique contributions to the understanding of neural synchrony given their relative advantages and limitations.
EEG measures the brain's electrical activity through the scalp. It is widely used to study neural synchrony because of its superior millisecond-range temporal resolution. Though susceptible to head movements, EEG still allows for exploring neural synchrony through naturalistic designs where people can interact socially. The downside to EEG is its relatively poor spatial resolution, which makes it difficult to elucidate spatial qualities of brain activation in social contexts.
fNIRS uses near infrared waves to measure the blood-oxygen-level-dependent (BOLD) response in the brain. It is an increasingly popular imaging method for neural synchrony studies because of its portability and motion tolerance, which makes it ideal for testing real-world social stimuli. fNIRS only measures the cortical regions of the brain, and its temporal resolution is not as fine as EEG. However, the balance between spatial and temporal properties, combined with subjects' ability to move around and interact with relative freedom during scanning, qualify fNIRS as a versatile option for exploring neural synchrony.
fMRI uses magnetic resonance to measure the brain's BOLD response. The major advantage of fMRI is the precise spatial resolution. fMRI allows researchers to examine in-depth neurocognitive processes that occur across brains. However, fMRI has low temporal resolution, is highly sensitive to motion, and requires that subjects lie flat in a loud MRI machine while interacting with a screen. These factors pose limitations to the study of neural synchrony, which often calls for naturalistic environments and tasks that are representative of real-world social contexts.
Analysis
A standard approach to investigating neural synchrony, especially with data from naturalistic experimental designs, is inter-subject correlation (ISC). Often, ISC is the Pearson correlation, or robust regression, of spatio-temporal patterns of neural activity in multiple subjects. In ISC, an individual's brain responses are either correlated across the average of the other subjects in a leave-one-out analysis, or all pairs of subjects are correlated in a pairwise analysis. This method leverages time-locked stimuli in order to understand how brain activity across participants relates to different parts of the task. Rather than focusing on the strength of activation in brain areas, ISC explores the variability in neural activity across subjects, allowing researchers to probe the level of similarity or idiosyncrasy in people's brain responses. Shared variance in neural activity is assumed to be indicative of similar processing of identical stimuli or tasks. Similar to the general linear model, it is important to compare ISC values to a null, which can be derived from recordings of resting states or irrelevant stimuli. Because it depends on extended designs that allow for activity recording over time, ISC is especially conducive to social interaction studies, which makes it a powerful approach for exploring neural synchrony in social contexts. However, ISC depends on stimulus-driven responses, which poses difficulties for researchers interested in resting-state activity.
Recently, inter-subject representational similarity analysis (IS-RSA) has been put forward as a way to detect the individual differences, or “idiosynchrony,” across people experiencing naturalistic experimental stimuli. This analysis takes the neural synchrony of each subject to the other subjects and relates it to known individual behavioral measures, allowing researchers to compare multi-person-level brain data with individual-level traits and behaviors.
Best practices
Neural synchrony is a relatively new area of study that affords a variety of approaches, and no prevailing paradigm exists to collect, analyze, and interpret the data. Many decisions, such as imaging techniques or analysis methods, depend on researchers’ goals. However, there are some generally agreed upon best practices when designing these experiments. For example, sample sizes of about 30 are necessary to acquire reliable and reproducible statistical ISC maps. Furthermore, when studying shared responses, researchers typically prefer a strong stimulus that is able to generate significant brain responses, allowing researchers to detect greater levels of neural synchrony across participants. The exception to this preference is when researchers are more interested in the individual differences that drive synchrony. In these cases, researchers should employ stimuli that are strong enough to evoke neural synchrony, yet modest enough to maintain sufficient neural variability that researchers can later relate to the variability in behavioral measures.
One of the biggest considerations for conducting neural synchrony studies concerns the ecological validity of the design. As an inherently social phenomenon, neural synchrony calls for multidimensional stimuli that emulate the richness of the social world. Furthermore, by nature of how it is measured—through computing the variance in multiple brains' responses to a task over time—neural synchrony is particularly amenable to extended social stimuli. Ecological designs are notably difficult in most neuroimaging studies, yet they are especially important for capturing social processes, and they also play to the strengths and affordances of neural synchrony approaches.
Experimental evidence and implications
Communication
Examining neural synchrony through multi-brain studies has offered insight into the shared and idiosyncratic aspects of human communication. As a potential neural mechanism for the effective transfer of information across brains, neural synchrony has shown how brain activity temporally and spatially couples when people communicate. Synchrony during communication occurs in a number of brain frequencies and regions, notably alpha and gamma bands, the temporal parietal junction, and inferior frontal areas.
In a seminal study, Stephens et al. demonstrated this inter-brain link through an fMRI analysis of speakers and listeners. Using the speaker's spatial and temporal neural responses to model the listener's responses during natural verbal communication, they found that brain activity synchronized in dyads in both a delayed and anticipatory manner, but this synchrony failed to occur when subjects did not communicate (e.g., speaking in a language the listener does not understand). Greater synchrony across brains, especially in the predictive anticipatory responses, indicated better scores on comprehension measures. Building on this work, other research has sought to pinpoint communicative factors associated with neural synchrony. By manipulating conversation modality and instruction, research has found that neural synchrony is strongest during face-to-face conversations that incorporate turn-taking behavior and multi-sensory verbal and nonverbal interaction. Network structure dynamics also play a role in neural synchrony, such that central figures, like conversation leaders, tend to show greater neural synchrony than non-leaders with other discussion partners.
Neural synchrony is also found in nonverbal communication, such as hand gestures and facial expressions. An early study found synchronization across participants playing a game of charades. Using fMRI to record brain activity as people gestured or watched the gestures, researchers found synchronized temporal variation in brain activity in mirror neuron and mentalizing systems. Another study showed that communicative behaviors like shared gaze and positive affect expression generated neural synchrony in romantic partners, though not in strangers. As a whole, neural synchrony studies surrounding verbal, multi-sensory, and nonverbal communication demonstrate its potential as a tool for exploring the underlying mechanisms of interpersonal communication.
Narrative processing
Another focus of neural synchrony studies involves narrative processing. This direction of research has some crossover with neural synchrony studies of communication, but there remains sufficient interest in the similarities and differences in how people specifically process multimodal narrative information, such as watching movies, hearing stories, or reading passages. Importantly, narrative processing studies of neural synchrony observe hierarchical levels of processing that unfold over time, starting in areas responsible for low-level processing of auditory or visual stimuli. As semantic information becomes more salient in the narrative, synchronized processing moves to more integrative networks, such as the inferior parietal lobe or temporal parietal junction.
Research shows that neural synchrony is indicative of the similarity in people's narrative recall and understanding, even for ambiguous narratives. One study demonstrated this phenomenon using Heider and Simmel's classic paradigm, where simple shapes move around the screen in a way that causes people to imbue the shapes with stories and social meaning. Participants who interpreted the movement of shapes in similar ways showed greater neural synchrony in cortical brain regions. This connection between neural synchrony and similarity in comprehension reliably occurs across other types of narratives, including listening to stories and free viewing of visual content, and it persists throughout different stages of the narrative, such as consuming the story, recalling the story, and listening to another person recall the story. Together, these findings highlight neural synchrony as a reliable neural mechanism for the convergence of people's hierarchical narrative processing, suggesting that synchrony plays a critical role in how, if, and why we see meaning in the world similarly.
Coordination
The pursuit of complex goals for individuals or groups depends on successful coordination, and neural synchrony provides a window into the underlying mechanisms of these processes as well. A review of hyperscanning research shows that neural synchrony approaches have explored coordination through a range of paradigms, including joint attention, movements, ideas, and tasks. These findings also demonstrate synchronization across a variety of brain areas associated with sharing actions and mentalizing, namely the inferior and temporal parietal areas, as well as alpha band and other frequencies. Furthermore, converging evidence suggests that inter-brain models (i.e., neural synchrony) are more effective than intra-brain models at predicting performance for tasks requiring social coordination.
Understanding how coordination via joint attention relates to neural synchrony, and how this relationship drives performance, is of particular interest to researchers. Research shows that even simple social interactions, like attention convergence, can induce synchrony. For example, in a task where one participant must direct another participant to a target location through eye gazing only, which requires that both participants eventually coordinate eye movements, researchers found significant neural synchrony in mentalizing regions of interacting pairs. Other studies show strong neural synchrony during simple coordinated events like hand and finger movement imitation, humming, and even eye-blinking.
Coordination studies also find neural synchrony in more complex social coordinations. A set of studies has demonstrated the prevalence of neural synchrony in music production while people coordinate rhythms and movements. Early studies showed that dyads of guitarists generate greater low frequency band neural synchrony when playing together than when playing solo. Also, people who performed distinct roles in an intricate musical piece showed synchrony between brains during periods of coordination. Another series of studies examined pilots and copilots in a flight simulator, finding that synchrony was strongest when the situation demanded more social coordination, such as during stressful scenarios or takeoff and landing. These findings implicate neural synchrony as a reliable correlate of social coordination, even when interactions call for coordination of various forms and complexities.
Cooperation
As measured through tasks that involve interactive decision-making and games, results from the field suggest a close association between neural synchrony and cooperation. Decision-making contexts and games that demand greater levels of social, high-level, and goal-directed engagement with other people are typically more conducive to neural synchrony. In this domain, researchers are particularly interested in how neural synchrony levels vary depending on whether people collaborate, compete, or play alone.
For example, one study that employed a computer video game found high levels of neural synchrony - and better performance - across subjects when they played on the same team, but this effect disappeared when people played against each other or by themselves. Similarly, researchers that administered a puzzle solving task found neural synchrony for people when they are working as a team, yet synchrony decreased for the same people when they worked separately or watched others solve the puzzle. Another study using a classic prisoner's dilemma game showed that participants experienced higher neural synchrony with each other in the high-cooperation-context conditions than they did in the low-cooperation-context conditions or when they interacted with the computer. Subjective measures of perceived cooperativeness mediated this effect. Critically, the idea that neural synchrony is robust during cooperation, that more interactive and demanding cooperative tasks recruit greater neural synchrony, and that better cooperation often links to better performance is corroborated throughout the neural synchrony literature.
Individual-level differences
Much of the neural synchrony literature examines how stimuli drive responses across multiple brains. Because these responses are often task-dependent, it becomes hard to disentangle state-level factors from individual-level factors (e.g., traits). However, creative experimental designs, access to certain populations, and advances in analysis methods, like IS-RSA, have offered some recent insight into how individual-level differences affect neural synchrony.
Using an ambiguous social narrative, Finn et al. report that individuals with high-trait paranoia showed stronger neural synchrony with each other in socially-motivated cortical regions than they did with low-trait paranoia subjects - a finding that also scales when examining the semantic and syntactic similarities of their narrative recall. Similarly, research shows that people's cognitive styles affect their level of synchrony with each other. In response to viewing a film, Bacha-Trams et al. demonstrated that holistic thinkers showed greater neural synchrony with each other, and presumably understood the film more similarly, than analytic thinkers did with each other. The two groups also exhibited within-group synchrony in different brain regions.
The idea that individual-level differences affect neural synchrony extends to clinical areas as well. Some research indicates that people who manage autism spectrum disorder exhibit distinct and diminished patterns of neural synchrony compared to people without autism spectrum disorder. Clinically driven discrepancies in neural synchrony have also been shown to increase along with symptom severity.
The brain-as-predictor approach
Neural synchrony has major implications for the brain-as-predictor approach, which encourages the use of neuroimaging data to predict robust, ecologically valid behavioral outcomes. The brain-as-predictor approach has been effective in predicting outcomes across a variety of domains, including health and consumer choices. Given its social nature, neural synchrony has the potential to build on brain-as-predictor models by allowing for predictions about real-world social processes. Some researchers have started to employ this approach.
In one study, members of a bounded social network watched a battery of short audiovisual movies in an MRI scanner. Hypothesizing that similarity in neural responses tracks with social closeness, the researchers used the strength of neural synchrony measures across participants to reliably predict real-world social network proximity and friendship. Another example of how neural synchrony can be leveraged to predict outcomes involves the use of neural reference groups, which can predict behaviors like partisan stance on controversial topics at above-chance levels. This approach requires identifying groups of people that perceive and respond to the world in similar ways, measuring their brain activity and dispositional attitudes related to any stimuli of interest, and then using a synchrony-based classification method to predict whether new individuals see the world similarly or differently depending on their synchrony with the reference group. Together, these findings illustrate the power and potential for neural synchrony to contribute to brain-as-predictor models, ultimately framing neural synchrony as a tool for understanding real-world outcomes above and beyond behavioral measures alone.
See also
Social cognition
Social neuroscience
Cognitive neuroscience
Behavioural synchrony
Brainwave entrainment
Group cohesiveness
Electroencephalography
Functional near-infrared spectroscopy
Functional magnetic resonance imaging
References
Wikipedia Student Program
Cognitive neuroscience
Neuroscience | Neural synchrony | [
"Biology"
] | 4,712 | [
"Neuroscience"
] |
69,271,754 | https://en.wikipedia.org/wiki/HD%2034868 | HD 34868 (HR 1758) is a solitary star located in the southern constellation Columba. With an apparent magnitude of 5.97, it's barely visible to the unaided eye. The star is located 410 light years away based on parallax, but is drifting away with a heliocentric radial velocity of 18 km/s.
Properties
HD 34868 is an ordinary A-type main-sequence star with a mass of 2.73 solar masses, and a radius of 3 solar radii. It radiates at 82 solar luminosities from its photosphere at an effective temperature of , which gives it a blueish-white hue of an A0 star. HD 34868 has a rapid projected rotational velocity of 103 km/s, and is a young star, with an age of 245 million years. However, some sources give it a classification of A1 IV, which makes it a subgiant star.
References
Columba (constellation)
1758
Columbae, 12
034868
024831
Durchmusterung objects
A-type main-sequence stars | HD 34868 | [
"Astronomy"
] | 230 | [
"Columba (constellation)",
"Constellations"
] |
69,272,019 | https://en.wikipedia.org/wiki/HD%2047475 | HD 47475 (HR 2445) is a solitary star located in the southern constellation Columba. With an apparent magnitude of 6.34, its barely visible to the naked eye under ideal conditions. The star is located 1,720 light years away from the Solar System, but is drifting away with a heliocentric radial velocity of 15.77 km/s.
Properties
HD 47475 has a classification of K0 II, which states its a bright giant that has exhausted hydrogen at its core and left the main sequence. It has four times the Sun's mass, but has expanded to 45 times the Sun's radius. It radiates at about 1,000 times the Sun's luminosity from its enlarged photosphere from an effective temperature of . HD 47475 has a projected rotational velocity of 5 km/s, which is fast for its class.
References
047475
K-type bright giants
2445
031603
Durchmusterung objects
Columba (constellation)
Columbae, 111 | HD 47475 | [
"Astronomy"
] | 216 | [
"Columba (constellation)",
"Constellations"
] |
69,274,109 | https://en.wikipedia.org/wiki/Turkesterone | Turkesterone is a phytoecdysteroid found in numerous plant species, including Ajuga turkestanica, various Vitex species, Triticum aestivum, and Rhaponticum acaule.
See also
Ecdysterone
References
Tertiary alcohols | Turkesterone | [
"Chemistry"
] | 62 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
69,274,191 | https://en.wikipedia.org/wiki/InterPore | The International Society for Porous Media (InterPore) is a nonprofit independent scientific organization established in 2008. It aims to advance and disseminate knowledge for the understanding, description, and modeling of natural and industrial porous medium systems. It acts as a platform for researchers active in modeling of flow and transport in natural, biological, and technical porous media, such as soils, aquifers, oil and gas reservoirs, biological tissues, plants, fuel cells, wood, ceramics, concrete, textiles, paper, polymer composites, hygienic materials, food, foams, membranes, etc.
History
In the course of 2006, researchers from the Department of Earth Sciences, Utrecht University and Institute for Modelling Hydraulic and Environmental Systems, University of Stuttgart, under the leadership of Professor Rainer Helmig and Professor Majid Hassanizadeh, respectively, developed a proposal for setting up a joint international graduate research program. The proposal was submitted to German Research Foundation (DFG) and Netherlands Organisation for Scientific Research (NWO), and was successfully funded. The research school started its activities on January 1, 2007, under the name NUPUS (Non-linearities and Upscaling in PoroUS Media). This project led to the idea of creating an international center for porous media wherein scientists from diverse disciplines who study porous media could exchange ideas and research activities. The European Society for Porous Media (Europore) was established in Spring, 2008. By Summer 2008, the geographical scope was expanded beyond Europe and the name was changed to the International Society for Porous Media (InterPore.) Bylaws were approved and the society was officially registered in Fall 2008.
InterPore Academy was established in 2020 to promote educational activities mainly to serve industrial and/or younger researchers. The academy is organizing short courses, webinars, and workshops.
National Chapters
National chapters are country-wide activity groups of InterPore. They form platforms for bringing together porous media researchers from academia and industry of a given country or region. A variety of activities, such as porous media workshops, conferences, short courses, are organized by national chapters. National chapters compile a list of porous media companies in their countries to be able to interact with institutions and industries.
As of 2021, InterPore has active national chapters in:
Australia
Benelux countries
Brazil
China
Colombia
France
Germany
Greece
India
Iran
Israel
Italy
Mexico
Norway
Saudi Arabia
Spain
United Kingdom
United States (Southern)
InterPore Annual Meetings
InterPore has organized the International Conference on Porous Media annually since 2009. General themes include: fundamentals of porous media; computational challenges in porous media simulation; experimental studies and applications involving porous media. Previous conferences have been hosted by in Fraunhofer ITWM in Kaiserslautern, Germany; Texas A&M University in College Station, Texas, USA; I2M-Dept TREFLE (CNRS, ENSAM, University of Bordeaux), France; Purdue University in West Layfayette, Indiana, USA; Technical University of Prague, Czech Republic; University of Wisconsin, in Milwaukee, USA; University of Padova, Italy; University of Cincinnati, Ohio, USA; Technical University of Delft in Rotterdam, Netherlands; Louisiana State University in New Orleans, USA; Universitat Politecnica de Valencia, Spain; and two online conferences (2020 & 2021.) InterPore2022 is scheduled for May 30 - June 2, 2022 at Khalifa University in Abu Dhabi, UAE.
References
Materials science organizations | InterPore | [
"Materials_science",
"Engineering"
] | 713 | [
"Materials science organizations",
"Materials science"
] |
69,274,247 | https://en.wikipedia.org/wiki/Toyota%20R32V/R36V%20engine | The Toyota R32V and R36V engine family are a series of turbocharged, 3.2-liter and 3.6-liter, 90-degree, four-stroke, V-8, gasoline racing engines, designed, developed and produced by Toyota for sports car racing; between 1988 and 1999. The engines were used in various Toyota sports prototype race cars.
Applications
Toyota 88C-V
Toyota 89C-V
Toyota 90C-V
Toyota 91C-V
Toyota 92C-V
Toyota 93C-V
Toyota 94C-V
Toyota GT-One
References
Toyota engines
Gasoline engines by model
Engines by model
Group C
V8 engines | Toyota R32V/R36V engine | [
"Technology"
] | 131 | [
"Engines",
"Engines by model"
] |
69,274,567 | https://en.wikipedia.org/wiki/Toyota%20RV10%20engine | The Toyota RV10 engine is a 72-degree, four-stroke, naturally-aspirated, V10 racing engine, designed, developed and produced by Toyota, for their Toyota TS010 Group C sports prototype race car, between 1991 and 1993.
Background
Due to rule changes in the World Sportscar Championship for 1992, Toyota was forced to replace their previous series of Group C engines, dubbed the R32-V and R36-V, which were 3.6L twin-turbocharged V8 engine units. The new rules required a 3.5L naturally aspirated engine to be used, similar to Formula One engine regulations at the time. Thus, in 1991, Toyota completed its RV10 engines and began early testing.
Due to the change in engines, a whole new chassis was also necessary in order to better handle the new V10. Former Tom Walkinshaw Racing designer Tony Southgate was in charge of designing the car that became the TS010, featuring a more aerodynamic and longer body than the C-V series of sportscars.
Applications
Toyota TS010
References
Toyota engines
Group C
Engines by model
Gasoline engines by model
V10 engines | Toyota RV10 engine | [
"Technology"
] | 236 | [
"Engines",
"Engines by model"
] |
69,275,023 | https://en.wikipedia.org/wiki/List%20of%20organisms%20named%20after%20famous%20people%20%28born%201800%E2%80%931899%29 | In biological nomenclature, organisms often receive scientific names that honor a person. A taxon (e.g. species or genus; plural: taxa) named in honor of another entity is an eponymous taxon, and names specifically honoring a person or persons are known as patronyms. Scientific names are generally formally published in peer-reviewed journal articles or larger monographs along with descriptions of the named taxa and ways to distinguish them from other taxa. Following rules of Latin grammar, species or subspecies names derived from a man's name often end in -i or -ii if named for an individual, and -orum if named for a group of men or mixed-sex group, such as a family. Similarly, those named for a woman often end in -ae, or -arum for two or more women.
This list is part of the List of organisms named after famous people, and includes organisms named after famous individuals born between 1 January 1800 and 31 December 1899. It also includes ensembles in which at least one member was born within those dates; but excludes companies, institutions, ethnic groups or nationalities, and populated places. It does not include organisms named for fictional entities (which can be found in the List of organisms named after works of fiction), for biologists, paleontologists or other natural scientists, nor for associates or family members of researchers who were not otherwise notable; exceptions are made, however, for natural scientists who are much more famous for other aspects of their lives, such as, for example, writers Vladimir Nabokov or Beatrix Potter.
Organisms named after famous people born earlier can be found in:
List of organisms named after famous people (born before 1800)
Organisms named after famous people born later can be found in:
List of organisms named after famous people (born 1900–1949)
List of organisms named after famous people (born 1950–present)
The scientific names are given as originally described (their basionyms); subsequent research may have placed species in different genera, or rendered them taxonomic synonyms of previously described taxa. Some of these names may be unavailable in the zoological sense or illegitimate in the botanical sense due to senior homonyms already having the same name.
List (people born 1800–1899)
See also
List of bacterial genera named after personal names
List of rose cultivars named after people
List of taxa named by anagrams
List of organisms named after the Harry Potter series
Notes
References
Named after celebrities 1800
Taxonomy (biology)
Organisms 1800
Organisms 1800
Organisms 1800
Taxonomic lists | List of organisms named after famous people (born 1800–1899) | [
"Biology"
] | 507 | [
"Lists of biota",
"Taxonomy (biology)",
"Taxonomic lists"
] |
69,275,247 | https://en.wikipedia.org/wiki/CYP23%20family | Cytochrome P450, family 23, also known as CYP23, is a nematoda cytochrome P450 monooxygenase family. The first gene identified in this family is the CYP23A1 from the Caenorhabditis elegans, is a homolog of the human gene CYP7B1.
References
Animal genes
23
Protein families | CYP23 family | [
"Biology"
] | 81 | [
"Protein families",
"Protein classification"
] |
69,275,290 | https://en.wikipedia.org/wiki/CYP25%20family | Cytochrome P450, family 25, also known as CYP25, is a nematoda cytochrome P450 monooxygenase family. The first gene identified in this family is the CYP25A1 from the Caenorhabditis elegans.
References
Animal genes
25
Protein families | CYP25 family | [
"Biology"
] | 67 | [
"Protein families",
"Protein classification"
] |
69,275,720 | https://en.wikipedia.org/wiki/ArtemiFlow | ArtemiFlow is a biotechnology Potsdam-based company founded in 2012 by Peter Seeberger. The company produces and sells drugs containing the active ingredient artemisinin from Artemisia annua and its derivatives to fight malaria, cancer and other diseases. As of 2019, Adam Maust is the CEO of ArtemiFlow.
Production process
ArtemiFlow is one of Peter Seeberger's companies for the production of low-cost medicines. With his team, he developed a process to produce artemisinin in large quantities in a cost-effective and environmentally friendly way, especially to meet the needs of developing countries. This was an innovative method as an alternative to Sanofi's genetic engineering one. Artemiflow developed a reactor for novel artemisinin production and developed higher-yielding plants in Kentucky in collaboration with the University Plants with higher yields.The new chemical production process is the first example of how not only the starting materials for making a drug or natural product are derived from plants. The catalyst, the tool that drives the reaction, also comes directly from plants.For developing the new process, Seeberger, Kerry Gilmore, and Andreas Seidel-Morgenstern were awarded the 2021 Science Prize for "Affordable Green Chemistry" by the American Chemical Society.
Development
Initial difficulties were the large-scale implementation of the manufacturing process, the cultivation of annual mugwort in Vietnam and the financing of the start-up. According to the first CEO Dirk Pohlmann, the company was hoping for support from the Bill and Melinda Gates Foundation. The latter supported competing products from the Sanofi company made from genetically modified yeast. According to Pohlmann's account, the foundation's monopoly position in funding the international fight against malaria made it difficult for ArtemiFlow to gain a foothold. In addition, simply announcing synthetic production dropped prices for producers, so less artemisinin was expected to be produced.
Partnerships
ArtemiFlow partnered with the University of Kentucky in 2018. Researchers at the university grew Artemisia annua, the plant that fights malaria, as part of the partnership. In 2020, the university and Artemiflow partnered on a clinical study to test the plant and its anti-cancer effects.
COVID-19
Production on the potential use of artemisin against COVID-19 was controversial, in part because of possible conflicts of interest owing to Seeberger's leadership of ArtemiLife. The critical article in the SZ was answered by an article in the German magazine Focus.
References
External links
Official website
Biotechnology companies
Biotechnology companies by country
Biotechnology companies established in 2012
Malaria | ArtemiFlow | [
"Engineering",
"Biology"
] | 520 | [
"Biotechnology organizations",
"Biotechnology companies by country",
"Biotechnology by country",
"Biotechnology companies"
] |
69,276,509 | https://en.wikipedia.org/wiki/Jupiter%27s%20South%20Pole | For the first time the South Pole of Jupiter was photographed in detail by the Juno spacecraft, which arrived to Jupiter in July 2016 and for the first time in history entered the polar orbit of Jupiter. At the same time, six cyclones were discovered at the South Pole: Оne in the center and five around it (their centers formed a close to regular pentagon), each about 4,500 km (2,800 mi.) in diameter, with a wind speed of about 360 km/h (220 mph), and all of them twisted clockwise. A similar picture at the North Pole of Jupiter presents nine cyclones of similar size: one in the center, and eight around it, rotating counterclockwise.
For more than three years the structure of cyclones at both poles of the nearest to us gas giant remained stable, but on November 3, 2019, on the 22nd rotation, "Juno" found the birth of a new cyclone at the South Pole: it quickly "pushed" the previous (although still has a smaller size, about 800 km), and now the centers of peripheral cyclones pole form almost right 6-corner.
Before Juno, only the Galileo probe entered Jupiter's orbit from 1995 to 2003; however, its orbital inclination made it impossible to observe the polar regions of Jupiter; Cassini, which flew past Jupiter in 2000, also had no opportunity to photograph the polar regions. Thus, they remained "white spots" until 2016 (the images of the previous flyby missions and Earth telescopes had low resolution); however, back in 2000, the polar X-ray spots of Jupiter (the southern one is significantly weaker than the northern one) were detected.
Jupiter's geographic South Pole is also the location of its magnetic South Pole (Jupiter does not have a well-defined magnetic North Pole).
References
Jupiter
Solar System
Space | Jupiter's South Pole | [
"Physics",
"Astronomy",
"Mathematics"
] | 372 | [
"Outer space",
"Space",
"Geometry",
"Spacetime",
"Solar System"
] |
69,276,603 | https://en.wikipedia.org/wiki/Analysing%20Interferometer%20for%20Ambient%20Air | Analysing Interferometer for Ambient Air (ANITA) is a trace gas monitoring system for the International Space Station (ISS). Monitoring air quality on ISS helps provide adequate life support for the crew. ANITA is developed by OHB and SINTEF under contract of ESA.
Working principle
ANITA is based on Fourier-Transform-Infrared-Spectroscopy FTIR. Each measured gas absorbs light in a certain frequency, these spectral lines are analysed and a gas concentration is calculated.
Development
ANITA-1 was operating from Sept 2007 until Aug 2008 on board the ISS. It weighed >55kg which was distributed in 2 Middeck Locker Inserts and a Laptop. Power consumption was approx. 150W. It was able to measure more than 32 trace gases on board the ISS.
ANITA-2 launched on SpaceX CRS-24 in Dec. 2021. It has been significantly reduced in size (1 Middeck Locker Insert) and mass (<38kg). The total power consumption is approx. 80W. It features WiFi Connection and a Touch Screen for a more versatile use. Compared to ANITA-1 it has a significantly increased (~factor 4) Signal to Noise Ratio allowing lower detection limits. ANITA-2 is calibrated to detect 37 gases, mostly with a detection limit well below 1ppm.
ANITA-2 was installed in an Express Rack inside the Destiny Lab by Matthias Maurer January 5, 2022. ANITA-2 is running nearly continuously on board the ISS since March 2022 and is monitoring the gas environment.
Usage
Using ANITA-1 Freon 218 was able to be detected on board the ISS, which was probably leaking from a Russian cooling loop.
References
External links
Overview of the project ANITA-2 at the website of SINTEF
Interferometers
Components of the International Space Station | Analysing Interferometer for Ambient Air | [
"Astronomy",
"Technology",
"Engineering"
] | 370 | [
"Interferometers",
"Astronomy stubs",
"Measuring instruments",
"Spacecraft stubs"
] |
69,278,585 | https://en.wikipedia.org/wiki/Kosmos%201408 | Kosmos-1408 () was an electronic signals intelligence (ELINT) satellite operated by the Soviet Union. It was launched into low Earth orbit on 16 September 1982 at 14:55 UTC, replacing Kosmos-1378. It operated for around two years before becoming inactive and left in orbit.
The satellite was destroyed in a Russian anti-satellite weapon test on 15 November 2021, resulting in space debris in orbits between above Earth. The threat of potential collision with debris caused the crew of the International Space Station (ISS) to take shelter in their escape capsules for the first few passes of the debris cloud, and increased the future risk of a debris collision with the ISS or other satellites.
Mission
From 1965 to 1967, the Soviet Yuzhnoye Design Office developed two satellite ELINT systems: Tselina-O for broad observations and Tselina-D for detailed observations. The ELINT payloads (satellites) for Tselina were first tested under the Kosmos designation in 1962–65. The Soviet Ministry of Defence could not convince the different parts of the Soviet military to decide between the two, so both systems were brought into service. The first production Tselina-O was launched in 1970. The Tselina-D took longer to enter service, due to delays with the satellite development and problems with the mass budget. The full Tselina system became operational in 1976. Continued improvements in the satellite systems led to Tselina-O being abandoned in 1984, with all of the capabilities of the two satellite systems being combined into Tselina-D.
Spacecraft
Kosmos-1408 was part of the Tselina-D system. It had a mass of around , and a radius of around . It is thought to have replaced Kosmos-1378 in the Tselina system, since it was launched into a similar orbital plane.
Kosmos-1408 was launched on a Tsyklon-3 launch vehicle on 16 September 1982, from Site 32/2, at the Plesetsk Cosmodrome. It was placed in low Earth orbit, with a perigee of , an apogee of , and an inclination of 82.5°. Its orbital period was 97.8 minutes.
The satellite had an expected lifespan of around six months, but it operated for around two years. The satellite could not be de-orbited after finishing operations because it did not have a propulsion system. Its orbit subsequently slowly decayed due to the small natural drag of the thermosphere.
Destruction
On 15 November 2021, at around 02:50 UTC, the satellite was destroyed as part of an anti-satellite weapons test by Russia. The direct-ascent anti-satellite A-235 "Nudol" anti-ballistic missile was launched from Plesetsk Cosmodrome at around 02:45 UTC. The system had been undergoing testing since 2014, but this was the first satellite it destroyed. The Outer Space Treaty, which Russia has ratified, bans some types of military activities in space, but not anti-satellite missiles using conventional warheads.
The destruction of the satellite and missile produced a cloud of space debris that threatened the International Space Station. The seven crew members aboard the ISS (four American, two Russian, one German) were told to put on their spacesuits and take shelter in the crew capsules so they could quickly return to Earth if debris struck the station. The satellite had been in orbit at an altitude ~50 kilometers (~30 miles) above the ISS orbital altitude, with the debris intersecting the orbit of the ISS every 93 minutes.
The crew sheltered for only the second and third passes through the debris field, based on an assessment of the debris risk. There is no evidence that any debris hit the station, but the risk of a potential impact was thought to be increased by a factor of five for the following weeks and months, and the longer term risk was doubled. In June 2022 the ISS had to manoeuvre to avoid a piece of debris from the satellite. The debris can also pose a risk to other low Earth orbit satellites, and several SpaceX Starlink satellites underwent manoeuvres to reduce the risk of collision with the debris. On 18 January 2022 there was a near miss (separated by only ) between a piece of debris and the Tsinghua Science Satellite.
On 15 November, the US State Department reported that it had identified about 1,500 pieces of debris that can be tracked by ground-based radar, and hundreds of thousands more that are more difficult to track. The same day, breakup of the satellite was independently confirmed by Numerica Corporation and Slingshot Aerospace. By 16 November 2021, the debris was orbiting at altitudes between ; by 17 November 2021 this range increased to .
On 18 November 2021, LeoLabs, a commercial tracking company, detected around 300 pieces and also estimated that there were around 1,500 ground-trackable pieces in total. They found this lower than expected, compared to other anti-satellite tests, meaning that the pieces are expected to have higher masses so will stay in orbit for longer, and that the lower-than-expected number of debris pieces might be because the event was not a hypervelocity collision. By 21 December, LeoLabs was tracking around 500 pieces of debris, including several large items that are thought to be the solar panels, antennas and booms from the satellite.
The low altitude of the satellite means the debris swarm is expected to be short-lived. only 300 of the initial 1,790 pieces of debris (17%) were still in orbit. Increasing solar activity during solar cycle 25 is causing the debris to decay at a faster rate than usual.
Reactions
The US State Department accused Russia of having targeted Kosmos 1408 during an anti-satellite weapon test, using a ground-based missile against their own defunct satellite, saying that it was "dangerous and irresponsible". On 15 November the Russian foreign minister, Sergei Lavrov, stated that there was no risk to the ISS or other peaceful uses of space. On 16 November, Sergei Shoigu, the Russian minister of defence, acknowledged that the destruction of the satellite was due to a Russian missile test, but argued that it posed no threat to any space activities.
NASA administrator Bill Nelson stated that: "With its long and storied history in human spaceflight, it is unthinkable that Russia would endanger not only the American and international partner astronauts on the ISS, but also their own cosmonauts." He added, "Their actions are reckless and dangerous, threatening as well the Chinese space station and the taikonauts on board."
The Secure World Foundation, a U.S. think tank, called upon the United States, Russia, China, and India to declare unilateral moratoriums on further testing of their anti-satellite weapons.
See also
1985 ASM-135 ASAT test – United States first anti-satellite missile test
2007 Chinese anti-satellite missile test
Gravity – 2013 science fiction movie in which a Russian satellite shoot-down creates a catastrophic Kessler syndrome–inciting debris swarm
Kessler syndrome – hypothetical runaway debris cascade making low Earth orbit inaccessible for centuries
Mission Shakti – 2019 Indian anti-satellite missile test
Operation Burnt Frost – 2008 United States satellite intercept
References
1982 in the Soviet Union
2021 in spaceflight
Intentionally destroyed artificial satellites
Kosmos satellites
Satellite collisions
Space debris
Space hazards
Space traffic management
Spacecraft launched in 1982
Spacecraft that broke apart in space | Kosmos 1408 | [
"Technology"
] | 1,531 | [
"Satellite collisions",
"Space debris",
"Spacecraft that broke apart in space"
] |
69,279,899 | https://en.wikipedia.org/wiki/McLaren%20M840T%20engine | The McLaren M840T engine is a , 90-degree, twin-turbocharged, flat-plane V8 petrol engine, designed, developed and produced by McLaren, in partnership and collaboration with Ricardo, and introduced with their 720S sports car model, in 2017. It is an evolution of the M838T engine, introduced in 2011.
Development
McLaren bought the intellectual property rights to the Tom Walkinshaw Racing developed engine, itself based on the Nissan VRH engine architecture, which was designed for the IRL IndyCar Series but never raced. However, other than the bore and stroke, little of that engine remains in the M840T.
Developed with help from Ricardo, the engine redlines at 8500 rpm, but 80% of the engine's torque is available as low as 2000 rpm. McLaren claims that the engine has the highest horsepower to emission ratio of any current production engine.
M840T engine uses double MHI turbochargers which names TD05H-06*20HF1T-12T. Despite the name, these are not the same turbochargers which used in the Mitsubishi Lancer Evo IX (X).
The engine is built at Ricardo's engine assembly facility in Shoreham-by-Sea, West Sussex.
Applications
McLaren's new M840T engine debuted as an evolution of the M838T used in the 650S. It is a twin-turbocharged V8 engine. However, the stroke has been lengthened by 3.6 mm to increase the capacity and 41% of the engine's components are new. The engine uses new twin-scroll turbochargers which have a low inertia titanium-aluminium turbines which spin with maximum efficiency with the help of actively controlled waste gates. The engine in the 720S was rated at a power output of at 7,500 rpm, giving the car its name; the maximum torque is at 5,500 rpm.
References
External links
Engines by model
Gasoline engines by model
McLaren Group
V8 engines | McLaren M840T engine | [
"Technology"
] | 414 | [
"Engines",
"Engines by model"
] |
69,280,228 | https://en.wikipedia.org/wiki/Ministry%20of%20Energy%2C%20Hydropower%20and%20Hydrocarbons%20%28Guinea%29 | The Ministry of Energy, Hydropower and Hydrocarbons is a Guinean government ministry whose current minister is Ibrahima Abé Sylla
Organization
Minister
Secretary General
Chef de Cabinet
Energy Advisor
Legal Advisor
Direction Nationale de l’Energie (DNE)
Bureau de Stratégie et de Développement (BSD)
Electricité de Guinée (EDG)
Agence Guinéene de l’Electrification Rurale (AGER)
Officeholders since 2010
References
Politics of Guinea
Guinea
Government ministries of Guinea | Ministry of Energy, Hydropower and Hydrocarbons (Guinea) | [
"Engineering"
] | 102 | [
"Energy organizations",
"Energy ministries"
] |
69,280,515 | https://en.wikipedia.org/wiki/FlyOver%20in%20Las%20Vegas | FlyOver in Las Vegas is a flying theater attraction and is the third FlyOver location operated by Pursuit, a subsidiary of Viad Corp. FlyOver in Las Vegas opened on September 1, 2021, on the Las Vegas Strip next to the Hard Rock Cafe on Las Vegas Boulevard South.
Description
FlyOver is a flight ride experience where riders are suspended in front of a 52-foot spherical screen, riding on a platform with six degrees of motion. The ride is designed to make you feel like you're flying in a helicopter over recognizable destinations such as the Grand Canyon, Lake Tahoe, Zion National Park and Arches National Park. The ride also includes special effects like wind, mist and location-specific scents.
FlyOver in Las Vegas has two 40-seat theaters and a full-service bar, The Lost Cactus, which is accessible without a ticket and serves beer, wine, cocktails, mocktails and snacks. FlyOver is available to guests of all ages. Children must be at least 40 inches tall to ride.
In addition to the FlyOver film, guests can experience a six-minute panoramic pre-show, which was created by Moment Factory. The pre-show is projected on 360-degree wrap-around screens and a central hanging medallion.
History
The construction of the attraction cost $40 to $45 million and consisted of converting the former United Artists movie theater and part of a Famous Footwear store into FlyOver. It took over a year and more than 100 hours of flight time with an actual helicopter to shoot all the video footage for FlyOver in Las Vegas's primary film, The Real Wild West.
The creative director for FlyOver in Las Vegas is Rick Rothschild, a former Disney Imagineer. Rothschild spent 40 years with Disney, during which he was responsible for developing the flight motion attraction Soarin’. After retiring from Disney, Rothschild spent three years working with Dave Mossop, a Cannes Lion Award-winning film director, to develop the FlyOver attractions and films in both Iceland and Las Vegas.
The first FlyOver location was opened in Vancouver, Canada in 2013 as FlyOver Canada and was later bought by Pursuit in December 2016. FlyOver Iceland, which is located in Reykjavik, Iceland, was opened in September 2019. In July 2019, Pursuit announced plans to open another FlyOver location in Toronto, Canada.
References
External links
FlyOver in Las Vegas official website
Amusement rides
Tourist attractions in Las Vegas | FlyOver in Las Vegas | [
"Physics",
"Technology"
] | 491 | [
"Physical systems",
"Machines",
"Amusement rides"
] |
69,280,791 | https://en.wikipedia.org/wiki/Crowd%20collapses%20and%20crushes | Crowd collapses and crowd crushes are catastrophic incidents that can occur when a body of people becomes dangerously overcrowded. When numbers are up to about five people per square meter, the environment may feel cramped but manageable; when numbers reach between eight and ten people per square meter, individuals become pressed against each other and may be swept along against their will by the motion of the crowd. Under these conditions, the crowd may undergo a progressive collapse where the pressure pushes people off their feet, resulting in people being trampled or crushed by the weight of other people falling on top of them. At even higher densities, the pressure on each individual can cause them to be crushed or asphyxiated while still upright.
Such incidents are invariably the product of organizational failures, and most major crowd disasters could have been prevented by simple crowd management strategies. Such incidents can occur at large gatherings such as sporting, commercial, social, and religious events. The critical factor is crowd density rather than crowd size.
Crowd collapses and crushes are often reported incorrectly as human stampedes, which typically occur when a large group of people all try to get away from a perceived risk to life.
Background
One study has calculated that there were 232 deaths and over 66,000 injuries in the ten years between 1992 and 2002 as a result of such incidents, but crowd scientists believe that such casualties are both vastly under-reported and increasing in frequency. One estimate is that only one in ten crowd injuries occurring in doorbuster sales are reported, while many, if not most, injuries at rock concerts go unreported.
Dynamics
The average individual occupies an oval floorspace approximately ——and at densities of 1 to 2 per square meter (or per ) individuals can move freely without contact. Even if people are moving quickly, at this density one can avoid obstacles, and the chance of a crowd-related incident is minimal. Even at three or four people per square meter, the risk is low; however, at densities of five per square meter, it becomes more difficult for individuals to move, and at higher densities of six to seven per square meter, individuals become pressed against each other and can be unable to move voluntarily. At this point a crowd can begin to behave like a fluid, with individuals moved about by the pressure of those around them, and shockwaves can pass through the crowd as pressures within the crowd change. This can be highly dangerous, although some people actively seek this experience, such as at rock concerts or football matches, where the excitement, camaraderie, and literally "going with the flow" is for some an essential part of the experience, and activities like dancing and moshing are common. The danger inherent in these conditions is that the crowd will collapse in on itself or become so densely packed that individuals are crushed and asphyxiated.
Crowd collapses
A crowd collapse occurs when a crowd is so dense that each individual is touching others all around and is, to an extent, supported by those around. This can occur whether the crowd is moving or stationary. If a person then falls, the support to those around is lost, while the pressure from those further out remains, causing people to fall into the void. This process is then repeated, causing a bigger void, and will progress until the pressure eases; meanwhile, those who have fallen are at risk of being smothered by the weight of bodies on top or being trampled as the crowd is swept over them.
An example of a progressive crowd collapse was the 2015 Mina stampede in Mecca, Saudi Arabia during the Hajj when over 2,400 people were reported to have died.
Crowd crushes
At even higher densities (approaching ) a crowd can become so packed that people are crushed together to such an extent they can no longer breathe and are asphyxiated. Such crowd crushes can occur when a moving crowd is funneled into a smaller and smaller space, when it meets an obstacle (such as a dead end, or a locked door), or when an already densely packed crowd has an influx of people, causing a pressure wave toward those at the front of the crowd. In this situation those entering may be unaware of the effect on those in front and continue to press in.
Examples of crushes are the Hillsborough disaster in Sheffield, South Yorkshire, England in 1989, the Love Parade disaster in Duisburg, North Rhine-Westphalia, Germany in 2010, the Astroworld Festival crowd crush in Houston, Texas, and the Itaewon Halloween crowd crush in Itaewon, Seoul, South Korea in 2022.
Crowd "stampedes"
The term "stampede" is usually used in reference to animals that are fleeing a threat. Stampede events that involve humans are extremely rare and are unlikely to be fatal. According to Keith Still, professor of crowd science at Manchester Metropolitan University, "If you look at the analysis, I've not seen any instances of the cause of mass fatalities being a stampede. People don't die because they panic. They panic because they are dying". Paul Torrens, a professor at the Center for Geospatial Information Science at the University of Maryland, remarks that "the idea of the hysterical mass is a myth". Incidents involving crowds are often reported by media as the results of panic. However, the scientific literature has explained how panic is a myth which is used to mislead the attention of the public from the real causes of crowd incidents, such as a crowd crush.
Causes of death
In crowd collapse and crush incidents the most common cause of death is asphyxiation, caused either by vertical stacking, as people fall on top of one another, or by horizontal stacking, where people are crushed together or against an unyielding barrier. Victims can also exhibit bone fractures caused by the pressure, or trampling injuries, when a crowd has swept over them where they have lain.
Prevention
It is believed that most major crowd disasters can be prevented by simple crowd management strategies. Crushes can be prevented by organization and traffic control, such as crowd barriers. On the other hand, barriers in some cases may funnel the crowd toward an already-packed area, such as in the Hillsborough disaster. Hence barriers can be a solution in preventing or a key factor in causing a crush. One problem is lack of feedback from people being crushed to the crowd pressing behind—feedback can instead be provided by police, organizers, or other observers, particularly raised observers, such as on platforms or horseback, who can survey the crowd and use loudspeakers to communicate and direct a crowd. In some cases it may be possible to take simple measures such as spreading movements out over time.
A factor that may contribute to a crush is inexperienced security officers who assume that people's behaviour in a dense crowd is voluntary and dangerous, and start applying force or preventing people from moving in certain directions. In the 1989 Hillsborough disaster, some police and stewards were so concerned with what they saw as possible hooliganism that they took actions that actually made matters worse.
There is risk of a crush when crowd density exceeds about five people per square meter. For a person in a crowd a signal of danger, and a warning to get out of the crowd if possible, is the sensation of being touched on all four sides. A later, more serious, warning is when one feels shock waves travelling through the crowd, due to people at the back pushing forward against people at the front with nowhere to go. Keith Still of the Fire Safety Engineering Group, University of Greenwich, said "Be aware of your surroundings. Look ahead. Listen to the crowd noise. If you start finding yourself in a crowd surge, wait for the surge to come, go with it, and move sideways. Keep moving with it and sideways, with it and sideways." Other recommendations include trying to remain upright, and keeping away from walls and other obstructions if possible.
After the 1883 crush known as the Victoria Hall disaster in Sunderland, England, which killed 183 children, a law was passed in England which required all public entertainment venues to be equipped with doors that open outwards—for example, using crash bar latches that open when pushed. Crash bars are required by various building codes.
See also
Ant mill
Emergent behavior
List of fatal crowd crushes
Notes
References
Sources
External links
How to stay safe at a crowded concert or music festival: CNN
Fire Safety Engineering Group
Interview with Paul Wertheimer (Crowd-safety expert) at Insider.com
"World's worst stampedes" – China Daily
Hazards
Man-made disasters
+ | Crowd collapses and crushes | [
"Biology"
] | 1,733 | [] |
76,673,018 | https://en.wikipedia.org/wiki/IRAS%2014348-1447 | IRAS 14348-1447 known as PGC 52270, are a pair of spiral galaxies located 1 billion light-years away in the constellation of Libra. The galaxy IRAS 14348-1447NE, is in the early process of merging with IRAS 14348-1447SW, causing gravity to pull stars from both galaxies and forming tidal tails. As the interaction takes place, molecular gas is swirled about and creating emission that is responsible for the galaxies' ultraluminous appearance.
IRAS 14348-1447, is classified a Seyfert 1 galaxy and has an active galactic nucleus, indicating certain activity in its supermassive black hole has awakened, possibly turning it into a quasar.
References
Luminous infrared galaxies
Interacting galaxies
Libra (constellation)
52270
IRAS catalogue objects
J14373831-1500239 | IRAS 14348-1447 | [
"Astronomy"
] | 178 | [
"Libra (constellation)",
"Constellations"
] |
76,673,219 | https://en.wikipedia.org/wiki/IC%2064 | IC 64 is a massive lenticular galaxy located 622 million light-years away in the Pisces constellation. IC 64 has a diameter of 300,000 light-years, making it, three times bigger than the Milky Way and one of the largest galaxies observed. IC 64 was discovered by French astronomer Stephane Javelle on 5 December 1893. It has an active galactic nucleus, and is an emission line galaxy.
References
Lenticular galaxies
0064
Pisces (constellation)
00613
003550
+04-03-031
003550
Astronomical objects discovered in 1893
Active galaxies | IC 64 | [
"Astronomy"
] | 121 | [
"Pisces (constellation)",
"Constellations"
] |
76,673,267 | https://en.wikipedia.org/wiki/Karl%20A.%20Smith | Karl A. Smith is a metallurgical engineer, academic and author. He is an emeritus Cooperative Learning Professor of Engineering Education at Purdue University's School of Engineering Education, as well as an emeritus Professor of Civil, Environmental, and Geo-Engineering, Morse-Alumni Distinguished University Teaching Professor, and Faculty Member at the Technological Leadership Institute at the University of Minnesota.
Smith's work has focused on developing research and innovation capabilities in engineering education, exploring cooperation in learning and design, and managing projects and knowledge. His publications comprise research articles and eight books including Teamwork and Project Management, How to Model it: Problem Solving for the Computer Age and New Paradigms for College Teaching. He is the recipient of the University of Minnesota Distinguished Alumni Award (2006), an Honorary Doctorate from the Universiti Teknologi Malaysia (2014) along with the Chester F. Carlson Award (2001), the Distinguished Service Award (2006), and the Lifetime Achievement Award (2015), all from the American Society for Engineering Education.
Smith is a Fellow of the American Association for the Advancement of Science and the American Society for Engineering Education, where he was inducted into the Hall of Fame in 2023. He served as the Guest Editor of a Special Issue of the Journal of Engineering Education, and as the Editor-in-Chief of Annals of Research on Engineering Education (AREE).
Education and early career
Smith earned a BS in Metallurgical Engineering from Michigan Technological University in 1969, subsequently working at an engineering firm in Moab, Utah. He returned to Michigan Tech to complete an M.S. degree in 1972 and then moved to Minneapolis for a research position at the University of Minnesota.
Career
Smith continued his academic career as an assistant professor at the University of Minnesota in 1980, later becoming associate professor in 1986 and Professor in 2004. In 2011 he served as Distinguished Engineering Education Innovation (EI) Fellow at the Hong Kong University of Science and Technology. He retired from the University of Minnesota in 2011 and between 2006 and 2022 he served as Cooperative Learning Professor of Engineering Education at Purdue University's School of Engineering Education. Also since 2011, he has held positions as an emeritus Professor of Civil, Environmental, and Geo-Engineering, Morse-Alumni Distinguished University Teaching Professor, and Faculty Member at the Technological Leadership Institute at the University of Minnesota. Additionally, in collaboration with Tony Starfield, Alan Wassyng, Sam Sharp, and others, he developed the civil engineering systems and "How to model it" courses for upper division and first-year students, respectively, which, alongside his work in cooperative learning and teamwork with David W. and Roger T. Johnson, led to the creation of the Civil Engineering Project Management course and the Management of Technology Project and Knowledge Management course.
Between 1999 and 2004, he had a split appointment with Michigan State University where he served as a Senior Consultant to the Provost for Faculty Development. At the University of Minnesota, he was the Co-coordinator of the Bush Faculty Development Program for Excellence and Diversity in Teaching from 1996 to 1997, Director of undergraduate studies in the Department of Civil Engineering from 1999 to 2004, and executive co-director and researcher in the STEM Education Research Center from 2012 to 2018. He was inducted into the Michigan Technological University Academy for Engineering Education Leadership in 2018.
Research
Smith has focused his research on mineral processing technology along with engineering education by facilitating faculty and graduate student professional growth, exploring the role of cooperation in learning and design, addressing problem formulation, modeling, and knowledge engineering, and managing projects and knowledge.
Engineering education
Smith's contributions to engineering education encompass work in cooperative learning and knowledge engineering applications. He published a paper in the Journal of Engineering Education, in 1981, introducing cooperative learning in engineering literature. During the early 1980s, he conducted some of the first randomized design empirical studies on cooperative learning in engineering classes. Subsequently, in the late 1980s, he transitioned from engineering research to education research, particularly focusing on cooperative learning and structured controversy, as his emphasis shifted towards teaching and research on project and knowledge management. This research addressed the critical needs of enhancing student learning, deepening understanding, and fostering collaborative skills. Beyond cooperative learning, his work included structured academic controversy, aimed at facilitating comprehensive understanding of complex issues through argument development and cooperative learning strategies.
Smith published books on this topic, including Active Learning: Cooperation in the College Classroom with David W. Johnson and Roger T. Johnson, providing strategies for college faculty to implement cooperative learning. They also co-authored Cooperative learning: Increasing College Faculty Instructional Productivity, in which they delved into the basics of cooperative learning, and he discussed how cooperative learning changed college teaching in New Paradigms for College Teaching that he co-edited with William E. Campbell. Later, in 2000, he wrote Teamwork and Project Management, where he emphasized key skills for engineering success, including teamwork, problem-solving, and project management.
Mineral processing technology
Smith worked on the development of technically and environmentally sound mineral and waste processing technologies. He laid the groundwork for various technical innovations, including a carbochlorination technique proposed for use in the processing of lunar anorthite. Alongside colleagues, he confirmed graphite's ability, with or without catalysts, to selectively reduce iron oxide in synthetic ilmenite, observed through isothermal weight loss over time from 850 °C to 1200 °C under argon atmosphere. Additionally, he explored reduction roasting processes using various reductants and desulfurizers to convert sulfide minerals to metallic form without sulfur dioxide emissions, capturing sulfur as either calcium sulfide or sodium sulfide.
Awards and honors
2001 – Chester F. Carlson Award, American Society for Engineering Education
2006 – Distinguished Alumni Award, University of Minnesota
2006 – Distinguished Service Award, American Society for Engineering Education
2014 – Honorary Doctorate, University of Technology Malaysia
2015 – Lifetime Achievement Award, American Society for Engineering Education
2023 – Hall of Fame, American Society for Engineering Education
Bibliography
Selected books
How to model it: Problem Solving for the Computer Age (1990) ISBN 978-0808779704
Active Learning: Cooperation in the College Classroom (1991) ISBN 978-0939603145
Cooperative learning: Increasing college faculty instructional productivity (1991) ISBN 978-1878380095
New paradigms for College Teaching (1997) ISBN 978-0939603268
Teamwork and Project Management, 4th edition, (2014) ISBN 978-0073534909
Selected articles
Johnson, D. W., Johnson, R. T., & Smith, K. A. (1998). Cooperative learning returns to college what evidence is there that it works?. Change: the magazine of higher learning, 30(4), 26–35.
Smith, K.A. (2000). Going deeper: Formal small-group learning in large classes. In MacGregor, J., Cooper, J., Smith, K, and Robinson, P., eds. Strategies for Energizing Large Classes: From Small Groups to Learning Communities. New Directions for Teaching and Learning, 81, 25–46. San Francisco: Jossey-Bass.
Johnson, D.W., Johnson, R.T., and Smith, K.A. (2000). Constructive controversy: The power of intellectual conflict. Change, 32 (1), 28–37.
Wankat, P. C., Felder, R. M., Smith, K. A., & Oreovicz, F. S. (2002). The scholarship of teaching and learning in engineering. In M.T. Huber & S.P. Morreale, eds., Disciplinary styles in the scholarship of teaching and learning, 217–237.
Smith, K. A., Sheppard, S. D., Johnson, D. W., & Johnson, R. T. (2005). Pedagogies of engagement: Classroom‐based practices. Journal of Engineering Education, 94(1), 87–101.
Johnson, D. W., Johnson, R. T., & Smith, K. (2007). The state of cooperative learning in postsecondary and professional settings. Educational psychology review, 19, 15–29.
Froyd, J. E., Wankat, P. C., & Smith, K. A. (2012). Five major shifts in 100 years of engineering education. Proceedings of the IEEE, 100(Special Centennial Issue), 1344–1360.
Singer, S. & Smith, K.A. (2013). Discipline-Based Education Research: Understanding and Improving Learning in Undergraduate Science and Engineering. Guest Editorial. Journal of Engineering Education, 102, 468–471.
Lichtenstein, G., Chen, H.L., Smith, K.A. & Maldonado, T.A. (2013). Retention and Persistence of Women and Minorities Along the Engineering Pathway in the United States. In A. Johri & B. Olds (Eds), Cambridge Handbook on Engineering Education Research.
Johnson, D. W., Johnson, R. T., & Smith, K. A. (2014). Cooperative learning: Improving university instruction by basing practice on validated theory. Journal on Excellence in University Teaching, 25(4), 1-26.
Streveler, R.A. & Smith, K.A. (2020). Opinion: Course Design in the Time of Coronavirus: Put on your Designer's CAP. Advances in Engineering Education, COVID-19 Issue.
Smith, K.A. & Starfield, A.M. (2023). Reflections on modeling and teaching modeling. The Journal of Undergraduate Mathematics and Its Applications (UMAP), 44(2).
Smith, K.A. & Felder, R.M. (2023). Cooperative Learning in Engineering Education: The Story of an Ongoing Uphill Climb. In Robyn Gillies, Barbara Millis, and Neil Davidson, eds. Contemporary Global Perspectives on Cooperative Learning. New York: Routledge.
References
Metallurgists
Fellows of the American Association for the Advancement of Science
Fellows of the American Society for Engineering Education
Purdue University faculty
University of Minnesota faculty
Michigan Technological University alumni
University of Minnesota alumni | Karl A. Smith | [
"Chemistry",
"Materials_science"
] | 2,098 | [
"Metallurgists",
"Metallurgy"
] |
76,673,660 | https://en.wikipedia.org/wiki/BnF%2C%20M%C3%A9langes%20de%20Colbert%2060 | Mélanges de Colbert 60 (Mel. Col. 60) is a medieval astronomical multiple-text manuscript preserved in the funds of Bibliothèque nationale de France. This manuscript was compiled, approximately, at the end of the 15th century, using different codicological units originating from the 14th and 15th century.
The main interest in the Mel. Col. 60 in the history of astronomy, are the different versions of the Oxford tables and John of Lignères' Tabule magne, which underlines the circulation of these famous alfonsine texts between continental Europe and the British Isles starting in the 14th century. Another peculiarity of this manuscript is that the canons and tables of the Tabule magne are conserved within the same codex, which is unusual for the transmission of this work
History
Little is known about the composition and provenance of Mel. Col. 60. It was composed around the end of the 15th century. However, the codex consists of several quires, some of which might be from the 14th century, while the others are from the 15th century. The manuscript is made partly of parchment, and partly of paper, which makes it easier for scholars to distinguish the quires of different provenance.
The identity of the compilator of Mel. Col. 60 remains unknown. There are at least two scribal hands that can be observed throughout the manuscript. For instance, the handwriting that copied John of Lignères' canon (starting on folio 34r) is different from one found on folios 42v or 43r, or from the one that has copied John of Mur's canon on folio 175r.
Content
Mel. Col. 60 is a type of astronomical manuscripts oriented towards practical use and containing various tables and canons that can assist in astronomical computations. The practical aim of Mel. Col. 60 is underlined by the high number of arithmetical tables, which show the compilator's interest in decimal numbers in particular.
The historical interest of the manuscript pertaining to alfonsine astronomy are different Oxford tables and John of Lignères' Tabule magne. However, Mel. Col. 60 contains other works, such as tables for mean motions of the luminaries and the planets (fol. 165r) or tables for conjunctions and oppositions from the year 1299 to 1525 (fol. 175r).
There are canons to the Tabulae permanentes by Firmin de Beauval and John of Murs that can be found on folio 175r.
Tabule magne
John of Lignères. was one of the key figures in the history of the Alfonsine astronomy, to be precise of its Parisian period. His work Tabule magne, consisting of tables accompanied by canons, was composed between 1320 and 1325. Later, John of Lignères integrated Tabule magne into a larger collection of his works, along with the treatises on Saphea and on Equatorium. In the 14th and 15th centuries the text had been circulating around Europe, but most important is its transmission to England, along with the other alfonsine material. The canons to the Tabule magne have been most likely composed by John of Lignères by combining different types of sources; some seem to be using original and alternative approaches to certain computations, while the others seem to follow a more traditional approach
Oxford tables
After flourishing in Paris during the 14th century, the Alfonsine tradition had made its way to the British Isles, which resulted, alongside other works, into the composition of so-called Oxford tables. Mel. Col. 60 begins with the Oxford tables: folios from 1v to 17r contain double argument tables for the Moon and the planets.
Further folios (63v–94r) contain Oxford tables (composed in 1348) attributed to William Batecombe, a 14th-century an English mathematician and astrologer, followed by the respective canons of the same authorship on folios 94v–96r.
References
Bibliothèque nationale de France
Astronomy books | BnF, Mélanges de Colbert 60 | [
"Astronomy"
] | 835 | [
"Astronomy books",
"Works about astronomy"
] |
76,674,337 | https://en.wikipedia.org/wiki/Hickson%2040 | Hickson 40 is a well-known galaxy group in the constellation Hydra. It consists of 6 separate members (three spiral galaxies, an elliptical galaxy, and a lenticular galaxy) and is in the stage of merging. Member galaxies of Hickson 40 interacted in the early stages of their formation to create a crowded galaxy sampler. Hickson 40 resides at a distance of 300 million light years and is so dense that it could even exist within a region close to the diameter of the Milky Way's galactic disk.
Location
Although Hickson 40 is remarkably self-sustained, the vast majority of galaxy clusters that resemble it are typically a part of larger galaxy cluster. It can be located in the Hydra constellation.
Formation
Researchers have observed Hickson 40 in many wavelengths, including visible light, radio, infrared, and X-ray. Majority of the galaxies within the cluster have a dense radio source in the cores, which could be proof for the existence of supermassive black holes. X-ray surveys have revealed that the galaxies are pushing closer together because of the amount of hot gas present. Infrared observations reveal fast rates of star formation. Hickson 40 is one of the most compact galaxy clusters ever observed, making it a valuable research point NASA. Research shows that galaxy cluster were more prevalent in the early universe, and helped the formation of quasars, whose luminosity from heated infalling material spread across the universe. Studying the formation of galaxies in other close groups like Hickson 40 have given astronomers a chance to sort out when and where galaxies assemble themselves, and what material they are made of.
Gallery
See also
Hickson Compact Group
Supercluster
Stephan's Quintet, a more famous HCG.
References
Sources
Galaxy clusters
40
Hydra (constellation) | Hickson 40 | [
"Astronomy"
] | 355 | [
"Hydra (constellation)",
"Galaxy clusters",
"Galaxy stubs",
"Astronomy stubs",
"Constellations",
"Astronomical objects"
] |
76,674,682 | https://en.wikipedia.org/wiki/Sonocatalysis | Sonocatalysis is a field of sonochemistry which is based on the use of ultrasound to change the reactivity of a catalyst in homogenous or heterogenous catalysis. It is generally used to support catalysis. This method of catalysis has been known since the creation of sonochemistry in 1927 by (1887–1975) and Robert Williams Wood (1868–1955). Sonocatalysis depends on ultrasounds, which were discovered in 1794 by the Italian biologist Lazarro Spallanzani (1729–1799).
Principle
General concept
Sonocatalysis is not a self-sufficient catalysis technique but instead supports a catalyst in the reaction. Sonocatalysis and sonochemistry both come from a phenomenon called “acoustic cavitation”, which happens when a liquid is irradiated by ultrasounds. Ultrasounds will create huge local variations of pressure and temperature, affecting the liquid's relative density and creating cavitation bubbles when liquid pressure decreases under its vapor pressure. When these bubbles blow up, some energy is released, which comes from the transformation of kinetic energy into heat. Sonocatalysis may happen in the homogenous phase or the heterogenous phase. This depends on the phase in which the catalyst is compared to the reaction.
The blowing of cavitation bubbles can cause intense local pressure and temperature conditions, going to a 1000 atm pressure and a 5000 K temperature. This may provoke the creation of highly energetic radicals. Bubbles' blowing causes the formation of hydroxyl radical HO^{.}and hydrogen radical H^{.}in a water-based environment. Next, these radicals may combine to produce different molecules, such as water H2O, hydroperoxyl HO2^{.} , hydrogen peroxide H2O2 and dioxygen O2
Radical formation reactions due to the decomposition of water by ultrasound can be described this way:
H2O ->[{)))}] HO{.} + H{.}
.OH + H. -> H2O2
.H + O2 ->HO2.
2HO. -> H2O2
2HO2.->H2O2 +O2
H2O +.OH->H2O2 +H.
Energy from ultrasonic irradiation differs from heat energy or electromagnetic radiation energy in time, pressure, and energy received by a molecule... For example, a 20 kHz ultrasound creates an 8.34 x 10−11 eV energy, while a 300 nm laser creates a 4.13 eV energy. This ultrasound causes a shorter reaction time and a better yield.
Direct and indirect irradiation
There are two types of irradiation in sonocatalysis and sonochemistry: direct irradiation and indirect radiation. In direct irradiation, the solution is in touch with a sound wave emitter (generally a transducer), while these two elements are separated by an irradiated bath in indirect irradiation. The bath transmits the radiations to the solution due to convection. While indirect irradiation is the most used irradiation technique, direct irradiation is possible too, especially when the irradiated bath may be the container for the solution too.
Catalysts
Homogenous catalysts
Metal carbonyls, such as Fe(CO)5, Fe3(CO)12, Cr(CO)6, Mo(CO)6 and W(CO)6, are very often used in homogenous catalysis, because these are stable species at standard temperature and pressure, due to their structures. Furthermore, their catalytic capacities are well-known and efficient.
Heterogenous catalysts
Carbon-based species like carbon nanotubes, graphene, graphene oxide, activated carbon, biochar, g-C3N4, carbon-doped materials, Buckminsterfullerene (C60), and mesoporous carbons, are very often used in heterogeneous sonocatalysis. These species are great sonocatalysts because they favour the degradation process during sonocatalysis. Furthermore, they have a huge activity and stability for sonocatalysis, and they show the nucleation effect. These properties come from features like optic activities, electrical resistivities and conductivities, chemical stabilities, forces, and their porous structures. These species are becoming more frequently used.
Materials
Transducers
Sonocatalysis needs equipment other than catalysts to generate ultrasound, like transducers that create ultrasound by the transformation from electrical energy to mechanical energy. There are two types of transducers: piezoelectric transducers and magnetostrictic transducers. Piezoelectric transducers are used more often because they are cheaper, lighter, and less bulky. These transducers are constituted of single crystals or ceramic and two electrodes fixed on the side of the precedent materials. These electrodes receive a voltage which equals at the most to the transducer's resonance frequency. Then, single crystals may be compressed or dilated, creating a wave.
Some examples of transducers
The ultrasonic cleaner is a bath full of liquid. The liquid can transmit acoustic energy from the bottom of the bath to the solution in the container. This cleaner often generates ultrasound with low frequencies (from 20 to 60 kHz) and is inexpensive. However, it has some inconveniences, like the difficulty of controlling the liquid temperature in the bath, and the fact that irradiation isn't equal everywhere in the bath
The cup-horn sonicator is similar to the ultrasonic cleaner, but it may irradiate using both direct and indirect irradiation. While ultrasonic cleaning only generates ultrasound with low frequencies, the cup-horn sonicator can generate ultrasound with high frequencies too, and with a higher intensity. However, this equipment is very expensive due to its conception.
The "whistle" reactor is a reactor in which the reaction mix is continuously pumped through an adjustable-width opening, in a delimited area where cavitation happens. Ultrasonic waves are generated in this area by the vibration of blades during the passing of the pumped solution. This reactor is often used for homogenous reaction mixes, as the solid part of heterogenous mixes cannot pass through the whistle. This type of reactor is less frequently used.
Applications
The use of sonocatalysis has risen. Today, sonocatalysis is used in lots of fields, like medicine, pharmacology, metallurgy, environment, nanotechnology, and wastewater treatment.
Health
Active ingredient synthesis
The example of pyrazole
Several studies showed that sonocatalysis could increase pyrazole synthesis yield, compounds that has antimicrobial, antihypertensive, anti-inflammatory and anticonvulsant activities.
A study developed a new way of synthesis for this molecule, using ecological and economical reactants while keeping a high yield and using sonocatalysis.
The following table contains is an example for the 3-methyl-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbothioamide synthesis:
(*) synthesis conditions are described on the picture above
Environment
Pollutants degradation
An example of the use of sonocatalysis is to degrade pollutants. Ultrasound can generate the HO^{.}radical from a water molecule. This radical is a strong oxidizing agent, which can degrade persistent organic pollutant. However, the reaction speed for hydrophobic compounds is low, so ultrasound is often paired with a solid catalyst. The addition of this catalyst means the addition of atomic nuclei that amplifies the cavity phenomenon, and so does the ultrasonic efficiency. Near the solid-liquid contact surface, pressure is applied on one of the sides of the bubble, causing a more violent blowing of the bubble.
46 cationic red bleaching
This principle can apply to the oxidated bleaching of 46 cationic red by zinc oxide held by bentonite. More than 10% to 20% of organic dyes are lost and released in nature. Finding new ways to improve dyes’ bleaching is an important topic, as these dyes may be toxic and carcinogenic. The oxidation comes from the HO^{.} radical, whose oxidant capacities are known. Indeed, we can observe that a higher concentration of the HO^{.} radical provokes a better 46 red cationic bleaching, as the yield for bleaching of cationic red is 17.8% before using ultrasound and 81.6% after using ultrasound. However, sonocatalysis’ efficiency mainly comes from the combination of both catalyst and ultrasound. For example, we observe a cationic red bleaching of only 25.4% by applying only ultrasound.
Tetracycline elimination
Another example of pollutant degradation is the elimination of tetracycline, an antibiotic that is frequently found as a pollutant in wastewater. When tetracycline is dissolved in aqueous solution, using only ultrasound is inefficient to degrade tetracycline, because it is kinetically unfavourable.
The addition of catalysts like titanium dioxide TiO2 or hydrogen peroxide H2O2 to ultrasound may speed up degradation: thirty minutes are enough when ultrasound and both catalysts are used.
Rhodamine B degradation
Sonocatalysis is used in rhodamine B degradation too. Rhodamine B is a synthetic dye that may be harmful for aquatic plant when released in wastewater.
Application to reactions
The Fenton's reaction
Sonocatalysis can be applied for reactions like Fenton's reaction. By associating sonocatalysis (at a 20 kHz frequency) and Fenton's reaction, with a 5.0 mg/L iron chloride ( FeCl2) mass concentration and a pH of 4, degradation efficiency is about 80% after 12 minutes.
References
Ultrasound
Physical chemistry
Catalysis | Sonocatalysis | [
"Physics",
"Chemistry"
] | 2,098 | [
"Catalysis",
"Applied and interdisciplinary physics",
"nan",
"Chemical kinetics",
"Physical chemistry"
] |
76,676,022 | https://en.wikipedia.org/wiki/Perceptual%20vigilance | In psychology and cognitive science, perceptual vigilance (also called perceptual sensitization) refers to a form of selective perception where a person has a heightened state of awareness and attentiveness towards specific stimuli or information, generally to satisfy a motive. This phenomenon involves individuals becoming more attuned to detecting and processing relevant sensory input or cues from their environment. Perceptual vigilance is influenced by various factors such as personal interests, goals or expectations.
This heightened perceptual sensitivity plays a crucial role in cognitive processes such as attention, perception, and memory. It involves selectively focusing attention on certain stimuli while filtering out irrelevant or less salient information. This selective attention allows individuals to prioritize and respond effectively to important or meaningful stimuli in their surroundings.
Researchers in psychology and cognitive science study perceptual vigilance to understand how attentional mechanisms operate and how they can be influenced by internal and external factors. By investigating the cognitive processes underlying perceptual vigilance, researchers gain insights into human perception, behavior and decision-making.
See also
Perceptual defense
Selective perception
References
Psychology
Cognitive science | Perceptual vigilance | [
"Biology"
] | 238 | [
"Behavioural sciences",
"Behavior",
"Psychology"
] |
76,676,467 | https://en.wikipedia.org/wiki/NGC%20833 | NGC 833 is an intermediate spiral galaxy in the constellation Cetus. It has an active Hubble-type Sa nucleus, and lies south of the celestial equator. It is estimated to be 173 million light-years from the Milky Way and about 75,000 light-years in diameter. Together with NGC 835, NGC 838 and NGC 839 it forms a group of galaxies cataloged as Hickson Compact Group 16 (Arp 318). Halton Arp divided his catalog of unusual galaxies into groups based on purely morphological criteria.
See also
Atlas of Peculiar Galaxies
Interacting galaxy
References
External links
NGC 833 at SEDS USA
Intermediate spiral galaxies
Interacting galaxies
Active galaxies
Cetus
0833
Astronomical objects discovered in 1785
Discoveries by William Herschel | NGC 833 | [
"Astronomy"
] | 150 | [
"Cetus",
"Constellations"
] |
76,677,167 | https://en.wikipedia.org/wiki/Pier%20%28bridge%20structure%29 | The pier of a bridge is an intermediate support that holds the deck of the structure. It is a massive and permanent support, as opposed to the shoring, which is lighter and provides temporary support.
History
Until the advent of concrete and the use of cast iron and then steel, bridges were made of masonry. Roman bridges were sturdy, semicircular, and rested on thick piers, with a width equal to about half the span of the vault.
It was only from 1750, with Jean-Rodolphe Perronet, that the thickness of the piers could be reduced. While it was considered an absolute rule to give them a thickness equal to one-fifth of the span, Perronet proposed and succeeded in having thicknesses equal to one-tenth of the span and rises varying between one-fifth and one-seventh accepted. These reductions significantly reduced the obstacle to water flow created by the structure. With a height of 92 meters, the piers of the Fades viaduct in France, inaugurated on 10 October 1909, are the tallest traditional masonry piers ever built.
Considerable progress was then made with the invention of modern natural cement discovered in 1791 by James Parker in England and especially through the work of Louis Vicat in France (1813–1818) who laid the foundations of the hydraulic binders industry and thus of concrete. The alliance with steel gave birth to reinforced concrete, allowing the construction of increasingly daring and economical structures. Paul Séjourné would be the last great theorist of masonry bridges, and his methods and formulas for calculating piers remain relevant today.
Piers then became more slender and taller. As early as 1937, considerable height was reached with the Golden Gate Bridge in the United States, which has pylons 230 meters tall.
A further leap forward occurred with the emergence of two new technologies: pre-stressed concrete developed by Eugène Freyssinet in 1928 and high-performance concrete in the 1980s. The combination of the two allowed for the construction of very tall piers.
Masonry piers
Morphology
In masonry bridge piers, there is a resistant part and a filling part:
The periphery of the shafts over a certain thickness constitutes the resistant part, made of dressed stones in the angles and squared or even rough stones.
The filling, at the core of the support, consists of rough stones or rubble, bonded or not by mortar, offering no particular characteristics of mechanical resistance and sometimes even of very poor and very heterogeneous quality.
Calculation
The dimensions of the supports result from the consideration of four criteria: stability against overturning, compression resistance of the support masonry, permissible pressure on the ground, and aesthetics.
However, the piers of the first bridges were not calculated, and the characteristics of the structures resulted from empirical formulas. The piers of the early structures were very robust to ensure the stability of the support during construction: each pier was self-stable under the thrust of the already built vault. Subsequently, technical evolution, such as simultaneous vault construction, allowed for refinement.
The thickness of the piers at the level of the vault spring lines is given by the formulas of Paul Séjourné.
Low piers
In this case, the height of the structure, measured between the top of the deck and the ground, is between the values a/3 and a/2, where a denotes the span of the arch, which is generally a semicircular or elliptical arch.
The thickness e of the pier depends solely on the span of the arches: a/10 < e < a/8.
High piers
The total height of the structure is generally between 1.5 a and 2.5 a.
The arches are semicircular, and their thickness T depends both on the span a of the arches and on the height H of the structure:
If H = 2.5 a, T = 0.1 a + 0.04H
If H < 2.5 a, T = 0.125 a + 0.04H
However, if the span a is small (a<8 m), it is preferable to use the following formula for T: T = 0.15 a + 0.4.
Concrete piers
Most of the piers of modern bridges are made of reinforced concrete or prestressed concrete for larger structures. Two types of forms are mainly encountered: columns or walls.
Each support can be composed of one or more walls or columns. The standard-shaped walls that can be found on most highways are represented in the illustration opposite.
Columns, being visible surfaces, are often subject to architectural research. This can result in a different section from the classic disk or specific surfaces. This is called architectural concrete.
Some structures have pile forms different from these two classic forms of column or wall. The deck of the Europe Bridge in Orléans is supported by particularly original tripodal piers.
Tall piles
A pile is considered tall when it exceeds 70 m. The slenderness, the ratio of the maximum diameter of the shaft to the height of the pile, is generally less than or equal to 1/10°. The compression exerted at the base of the pile is accentuated both by the weight of the pile itself and by the weight of the supported deck, as tall height generally combines, for architectural reasons, with long span. Therefore, this is a logical and sometimes privileged area for the use of high-performance concrete.
Used concrete
High-performance concretes are manufactured by reducing the porosity of the concrete, which means reducing the ratio E/C of the mass of water to that of cement per 1 m3 of concrete. A ratio E/C below 0.4 generally corresponds, with common cements, to the domain of HPC (the strength then exceeds 50 MPa). In practice, to overcome the decrease in workability of the concrete due to low E/C ratios, superplasticizers are used to deflocculate the fines (cement, mineral additions, ultra-fines).
The composition of the HPC80 concrete used for the Elorn Bridge was as follows:
Saint-Vigor CPA HP PM cement: 150 kg/m3
Saint-Renan 0/4 sand: 744 kg/m3
Kerguillo 4/10 gravel: 423 kg/m3
Kerguillo 10/16 gravel: 634 kg/m3
Silica fume (8%): 36 kg/m3
Plasticizer (3.95%): 18 kg/m3
Setting retarder: 1.6 kg/m3
Water (E/C ratio = 0.32): 132 kg/m3
Construction method
Two construction methods can be used to build tall piers:
Climbing or self-climbing formwork is the most commonly used method in France. The formwork relies on the already concreted part to rise to a determined height. However, concrete resumption is necessary each time the concreting is stopped. The piers of the Millau Viaduct and the Verrières Viaduct were built using this method.
Sliding formwork consists of continuously moving a formwork at a speed between 10 and 30 cm per hour. This technique avoids concrete resumption. The Tsing Ma Bridge (1997) in Hong Kong, the Skarnsundet Bridge (1991), or the Helgeland Bridge (1990) in Norway were built using this method.
The world's tallest piers
Structures with the tallest piers in the world are concentrated in Europe, specifically in France, Germany, and Austria. The first of these is the Millau Viaduct, which has the tallest pier in the world and two others in the top nine. The list of the fifteen tallest piers is as follows.
See also
Bridge
Bridge bearing
References
Bibliography
Bridges
Building
Piers by country | Pier (bridge structure) | [
"Engineering"
] | 1,547 | [
"Construction",
"Building",
"Structural engineering",
"Bridges"
] |
76,678,956 | https://en.wikipedia.org/wiki/Balsamia%20oregonensis | Balsamia oregonensis is a species of ascomycete fungus in the family Helvellaceae. It is the type species of the genus Barssia, and is commonly found in Oregon, which it is named for.
Description
Balsamia oregonensis is reddish-yellow in color and between in diameter. Its exterior appears lumpy and rounded in nature with less distinct warts then other truffles. The exterior folds into itself at a singular point, and the entirety of the exterior is covered in coarse hyphae. The interior of B. oregonensis is translucent white and appears marbled. The interior has central channels which do not appear translucent and somewhat mimics the exterior in shape/form, not unlike the human brain, these channels penetrate the gleba in multiple places.
Reproduction
Balsamia oregonensis releases its fungal spores seasonally in the spring and into early summertime.
Consumption
By humans
Balsamia oregonensis is an edible species of truffle and is described as having a pleasant taste. While edible, B. oregonensis is not often found in large enough quantities to be considered a regular delicacy even where it is most prevalent.
By animals
There is evidence that B. oregonensis is seasonally consumed by other animals, such as chipmunks, within its ecosystem.
History
Balsamia oregonensis was first described by Helen Gilkey in 1925, who named it in honor of Professor H. P. Barss who first collected B. oregonensis in Oregon. This was then published in the Journal Mycologia, from the Mycological Society of America in December of 1925 Vol. 17 No. 6.
Ecological associations
Balsamia oregonensis is commonly found alongside Douglas Fir trees which are considered its primary host. This association is useful in truffling and the best way to locate B. oregonensis in the wild.
Location
As its name suggests, Balsamia oregonensis is primarily found in Oregon, United States, although it is not exclusive to the area. Other areas within the United States where B. oregonensis can be found includes the Great plains region.
B. oregonensis has reportedly also been found in the Polish Tatra Mountains.
References
Pezizales
Fungus species | Balsamia oregonensis | [
"Biology"
] | 453 | [
"Fungi",
"Fungus species"
] |
76,679,567 | https://en.wikipedia.org/wiki/Hyzetimibe | Hyzetimibe is a pharmaceutical drug that inhibits cholesterol absorption. It targets the NPC1-like intracellular cholesterol transporter 1.
It reduces plasma levels of low-density lipoprotein cholesterol (LDL-C) by blocking the Niemann-Pick C1-like 1 protein, a transporter mainly found in the intestine that allows dietary cholesterol to enter the body from the intestinal lumen.
In China, it is used as a lipid-lowering agent and it has efficacy similar to ezetimibe.
References
Beta-lactams
Hypolipidemic agents
4-Fluorophenyl compounds
4-Hydroxyphenyl compounds
Primary alcohols
Azetidines | Hyzetimibe | [
"Chemistry"
] | 159 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
76,679,596 | https://en.wikipedia.org/wiki/Balsamia%20gunerii | Balsamia gunerii is a species of fungus from the genus Balsamia. It was previously listed in genus Barssia.
Description
Balsamia gunerii has a reddish-brown exterior and is roughly between in diameter. It has a coarse and bumpy skin with a textured white interior that appears like styrofoam.
Distribution
Balsamia gunerii is found in Turkey.
References
Pezizales
Fungi of Turkey
Fungus species | Balsamia gunerii | [
"Biology"
] | 94 | [
"Fungi",
"Fungus species"
] |
76,679,651 | https://en.wikipedia.org/wiki/Barssia%20yezomontana | Barssia yezomontana is a species of fungus from the genus Barssia. First described by Kobayasi in 1938.
Distribution
Barssia yezomontana is primarily found in Northern Japan, it was originally found in Yezo (Hokkaido).
References
Pezizales
Fungus species
Fungi of Japan | Barssia yezomontana | [
"Biology"
] | 63 | [
"Fungi",
"Fungus species"
] |
76,679,775 | https://en.wikipedia.org/wiki/Steven%20J.%20van%20Enk | Steven Jacob van Enk (born 1965) is a physicist on the faculty of the University of Oregon whose fields of study are theoretical quantum information and quantum optics.
Early life and education
Born in 1965 in Veenendaal, the Netherlands, Steven J. van Enk lived in Holland until 1993. He earned a Ph.D. at the Universiteit Leiden in 1992.
Van Enk is a national FIDE Master chess player.
Career
Van Enk held postdoc positions at the MaxPlanck Institute of Quantum Optics, at the University of Innsbruck, and at Cal Tech, where he worked with H. Jeff Kimble, a leading theorist in quantum information. Van Enk was then a member of the technical staff at Bell Labs for six years.
In 2006 van Enk joined the University of Oregon Physics Department, where he became a full professor in 2009. His work has been partially supported by N.S.F. grants.
Selected publications
Awards, honors
2010 American Physical Society Fellow, cited "For pioneering contributions in theoretical quantum information and quantum optics, including entanglement verification, quantum communication and teleportation, and angular momentum of photons."
See also
Cat state
References
External links
Physics leaves most behind
Star Trek fantasy is closer and Scientists Take Step Toward Star Trek Fantasy (cont. from p.1)
1965 births
Living people
Theoretical physicists
University of Oregon faculty | Steven J. van Enk | [
"Physics"
] | 281 | [
"Theoretical physics",
"Theoretical physicists"
] |
76,679,925 | https://en.wikipedia.org/wiki/Barssia%20guozigouensis | Barssia guozigouensis is a species of fungus from the genus Barssia.
Description
Barssia guozigouensis has a finely bumpy, and dark brown exterior. The interior is tan with comparatively large wrinkles to the size of the fungus.
Distribution
Barssia guozigouensis is primarily found in Western Europe on the border between France and Switzerland. It has also been located in China.
References
Pezizales
Fungi of Europe
Fungus species | Barssia guozigouensis | [
"Biology"
] | 95 | [
"Fungi",
"Fungus species"
] |
76,682,917 | https://en.wikipedia.org/wiki/Sculpture%20of%20Shakira | The sculpture of Shakira is a monument of Colombian singer Shakira that is located outside the Roberto Meléndez Metropolitan Stadium, in Barranquilla, Colombia.
Features
The sculpture made of steel measures 5 meters high and represents the Barranquilla artist Shakira standing with a guitar. The monument stands for the artist's successful career and the "musical triumphs she has given to the country." It is located just outside the Estadio Metropolitano Roberto Meléndez.
2023 statue
Since December 26, 2023, a second Shakira statue has been displayed in Barranquilla on a promenade along the Magdalena River.
References
2006 sculptures
Barranquilla
Outdoor sculptures in Colombia
Shakira
Sculptures of women in Colombia
Statues in Colombia
Colossal statues
Sculptures of musical instruments | Sculpture of Shakira | [
"Physics",
"Mathematics"
] | 159 | [
"Quantity",
"Colossal statues",
"Physical quantities",
"Size"
] |
76,682,938 | https://en.wikipedia.org/wiki/UGC%204881 | UGC 4881 (also known as The Grasshopper) is a pair of interacting galaxies, UGC 4881A and UGC 4881B. They are located in the constellation Lynx, some 500 million light-years away. UGC 4881, the brighter, is a peculiar spiral galaxy. It has been heavily documented by the Hubble Space Telescope, and is cataloged in the Atlas of Peculiar Galaxies.
Etymology
UGC 4881 was first given the nickname "The Grasshopper" by astrophysicist Dr. Boris Vorontsov-Velyaminov in a 1977 paper due to its resemblance to a grasshopper larva. It has also been informally called the "Shrimp galaxy" due to the curvature of the arm resembling a shrimp.
Morphology
The two galaxy cores are the two brightest regions in the object. The cores of each merging galaxy are separated and distinct, but the disks of the galaxies have started to merge. Intense star formation is occurring, as seen by the bright blue line of clusters along the grasshopper's "tail". Three other faint galaxies are visible near UGC 4881 and form a group with it.
Formation
UGC 4881 is believed to be in the process of merging, but the discs of the parent galaxies are overlapping while the cores are separated. A supernova exploded inside of UGC 4881 in 1999 and the galaxy is in the beginning of star formation.
See also
Halton Arp
Starburst galaxy
References
Interacting galaxies
Lynx (constellation)
04881
+08-17-065
026132
055 | UGC 4881 | [
"Astronomy"
] | 329 | [
"Lynx (constellation)",
"Constellations"
] |
76,682,944 | https://en.wikipedia.org/wiki/NGC%203125 | NGC 3125 is a large starburst galaxy in the constellation Antlia. It is located approximately 50 million light-years away from Earth. Starburst galaxies are galaxies in which unusually high numbers of new stars are forming, springing to life within intensely hot clouds of gas.
Morphology
NGC 3125 is notable as it displays large and violent bursts of star formation. Some of these stars are notable; one of the most extreme Wolf–Rayet star clusters in the local Universe, NGC 3125-A1, resides within NGC 3125.
Nearby galaxies
NGC 3125 is member of the LGG 189 Group, which also includes the galaxies NGC 3113, NGC 3137, and NGC 3175.
See also
List of NGC objects (3001–4000)
Star formation
References
Antlia
Starburst galaxies
3125
29366
435-G041
-05-24-022 | NGC 3125 | [
"Astronomy"
] | 180 | [
"Antlia",
"Constellations"
] |
76,683,114 | https://en.wikipedia.org/wiki/UGC%2011105 | UGC 11105, also known as PGC 61361, is a relatively nearby spiral galaxy located 109 million light-years (33.4 Mpc) away in the Hercules constellation. The galaxy is outshone by bright stars in the foreground. From the perspective on Earth, the Sun is 14 thousand trillion times brighter as compared to UGC 1105, if we to calculate the apparent magnitude for both objects. It is a possible active galactic nucleus candidate, according to SIMBAD.
One supernova has been observed in UGC 11105: SN 2019pjs (type II, mag. 17.3).
References
Spiral galaxies
Hercules (constellation)
61361
11105
+04-42-024 | UGC 11105 | [
"Astronomy"
] | 151 | [
"Hercules (constellation)",
"Constellations"
] |
76,683,306 | https://en.wikipedia.org/wiki/PGC%202456 | PGC 2456 known as KAZ 364 and JO201, is a spiral galaxy located in the constellation of Cetus. It is located 617 million light-years away from the Solar System. A member of Abell 85, PGC 2456 lies 360 kiloparsecs from the brightest cluster galaxy, Holmberg 15A.
PGC 2456 contains an active galactic nucleus. It is a low-excitation radio galaxy, with a stellar mass of 3.6 x 1010 M⊙.
PGC 2456 is considered a jellyfish galaxy due to the fact the tendrils are seen drifting downwards from its core. It exhibits intensive star formation in its tendrils and is the Ultraviolet-brightest cluster galaxy in Abell 85.
Such jellyfish galaxies are formed when galaxies like PGC 2456, moves through high speeds across the galaxy clusters, causing ram pressure to strip gas. According to studies, researchers estimated PGC 2456 might have lost about 50% of its mass when undergoing ram-pressure stripping.
See also
PGC 29820
PGC 1228197
Jellyfish galaxy
References
Spiral galaxies
02456
Cetus
Radio galaxies | PGC 2456 | [
"Astronomy"
] | 237 | [
"Cetus",
"Constellations"
] |
76,683,450 | https://en.wikipedia.org/wiki/IC%205337 | IC 5337 or JW100, is a spiral galaxy located 800 million light-years away from the Solar System in the constellation of Pegasus.
It was discovered by French astronomer, Stephane Javelle on November 25, 1897 and is probably gravitationally bound to IC 5338, the brightest cluster galaxy in Abell 2626. According to SIMBAD, IC 5337 is considered an emission-line galaxy.
IC 5337 is a jellyfish galaxy, mainly due to ram pressure. Star-forming gas are thrown about, as the galaxy penetrates through the thin gas layer and causing them to drip from the galaxy's disc, giving it its unique appearance of a cosmic jellyfish. It has a stellar mass of 3.2 × 1011 M⊙ and contains an active galactic nucleus likely trigged by accretion of matter into its supermassive black hole.
In addition, IC 5337 also shows an X-ray source.
See also
IC 4141
PGC 2456
Jellyfish galaxy
References
Pegasus (constellation)
Spiral galaxies
5337
+03-60-012
071875
071875
Astronomical objects discovered in 1897 | IC 5337 | [
"Astronomy"
] | 229 | [
"Pegasus (constellation)",
"Constellations"
] |
76,683,769 | https://en.wikipedia.org/wiki/NGC%204680 | NGC 4680 is a spiral/lenticular galaxy in the constellation Virgo. It is estimated to be 106 million light-years from the Milky Way and has a diameter of about 45,000 ly. In the same area of the sky there are, among other things: the galaxies NGC 4700 and NGC 4708. NGC 4680 was discovered on May 27, 1835, by John Herschel using an 18-inch reflecting telescope, who described it as "eF, S, has one or two small stars entangled in it".
One supernova has been observed in NGC 4680. SN 1997bp (type Ia, mag. 13.8) was discovered by Robert Evans on 6 April 1997.
See also
List of NGC objects (4001–5000)
References
External links
Spiral galaxies
Lenticular galaxies
Virgo (constellation)
4680
043118
-02-33-007
Astronomical objects discovered in 1835
Discoveries by John Herschel
12443-1121 | NGC 4680 | [
"Astronomy"
] | 201 | [
"Virgo (constellation)",
"Galaxy stubs",
"Astronomy stubs",
"Constellations"
] |
76,684,152 | https://en.wikipedia.org/wiki/NGC%20626 | NGC 626 is a very large barred spiral galaxy located in the constellation Sculptor. Its speed relative to the cosmic microwave background is 5,475 ± 16 km/s, which corresponds to a Hubble distance of 80.8 ± 5.7 Mpc (~264 million ly). NGC 626 was discovered by British astronomer John Herschel in 1834.
The luminosity class of NGC 626 is III and it has a broad HI line.
NGC 626 has a surface brightness equal to 14.13 mag/am2, which classifies NGC 626 as a low surface brightness galaxy (LSB). LSB galaxies are diffuse (D) galaxies with a surface brightness less than one magnitude lower than that of the ambient night sky.
Gallery
See also
List of NGC objects (1–1000)
European Southern Observatory
References
External links
Barred spiral galaxies
Sculptor (constellation)
0626
05901
Discoveries by John Herschel
Astronomical objects discovered in 1834
297-6
-7-14-18 | NGC 626 | [
"Astronomy"
] | 203 | [
"Constellations",
"Sculptor (constellation)"
] |
76,686,234 | https://en.wikipedia.org/wiki/Join%20count%20statistic | Join count statistics are a method of spatial analysis used to assess the degree of association, in particular the autocorrelation, of categorical variables distributed over a spatial map. They were originally introduced by Australian statistician P. A. P. Moran. Join count statistics have found widespread use in econometrics, remote sensing and ecology. Join count statistics can be computed in a number of software packages including PASSaGE, GeoDA, PySAL and spdep.
Binary data
Given binary data distributed over spatial sites, where the neighbour relations between regions and are encoded in the spatial weight matrix
the join count statistics are defined as
Where
The subscripts refer to 'black'=1 and 'white'=0 sites. The relation implies only three of the four numbers are independent. Generally speaking, large values of and relative to imply autocorrelation and relatively large values of imply anti-correlation.
To assess the statistical significance of these statistics, the expectation under various null models has been computed. For example, if the null hypothesis is that each sample is chosen at random according to a Bernoulli process with probability
then Cliff and Ord show that
where
However in practice an approach based on random permutations is preferred, since it requires fewer assumptions.
Local join count statistic
Anselin and Li introduced the idea of the local join count statistic, following Anselin's general idea of a Local Indicator of Spatial Association (LISA). Local Join Count is defined by e.g.
with similar definitions for and . This is equivalent to the Getis-Ord statistics computed with binary data. Some analytic results for the expectation of the local statistics are available based on the hypergeometric distribution but due to the multiple comparisons problem a permutation based approach is again preferred in practice.
Extension to multiple categories
When there are categories join count statistics have been generalised
Where is an indicator function for the variable belonging to the category . Analytic results are available or a permutation approach can be used to test for significance as in the binary case.
Spatial analysis
Covariance and correlation
References | Join count statistic | [
"Physics"
] | 424 | [
"Spacetime",
"Space",
"Spatial analysis"
] |
76,689,273 | https://en.wikipedia.org/wiki/Spatial%20weight%20matrix | The concept of a spatial weight is used in spatial analysis to describe neighbor relations between regions on a map. If location is a neighbor of location then otherwise . Usually (though not always) we do not consider a site to be a neighbor of itself so . These coefficients are encoded in the spatial weight matrix
Where is the number of sites under consideration. The spatial weight matrix is a key quantity in the computation of many spatial indices like Moran's I, Geary's C, Getis-Ord statistics and Join Count Statistics.
Contiguity-Based Weights
This approach considers spatial sites as nodes in a graph with links determined by a shared boundary or vertex. The elements of the spatial weight matrix are determined by setting for all connected pairs of nodes with all the other elements set to 0. This makes the spatial weight matrix equivalent to the adjacency matrix of the corresponding network. It is common to row-normalize the matrix ,
In this case the sum of all the elements of equals the number of sites.
There are three common methods for linking sites named after the chess pieces which make similar moves:
Rook: sites are neighbors if they share an edge
Bishop: sites are neighbours if they share a vertex
Queen: sites are neighbours if they share an edge or a vertex
In some cases statistics can be quite different depending on the definition used, especially for discrete data on a grid. There are also other cases where the choice of neighbors is not obvious and can affect the outcome of the analysis. Bivand and Wong describe a situation where the value of spatial indices of association (like Moran's I) depend on the inclusion or exclusion of a ferry crossing between counties. There are also cases where regions meet in a tripoint or quadripoint where Rook and Queen neighborhoods can differ.
Distance-Based Weights
Another way to define spatial neighbors is based on the distance between sites. One simple choice is to set for every pair separated by a distance less than some threshold . Cliff and Ord suggest the general form
Where is some function of the distance between and and is the proportion of the perimeter of in contact with . The function
is then suggested. Often the term is not included and the most common values for are 1 and 2. Another common choice for the distance decay function is
though a number of different Kernel functions can be used. The exponential and other Kernel functions typically set which must be considered in applications.
It is possible to make the spatial weight matrix a function of 'distance class': where denotes the 'distance class', for example corresponding to first, second, third etc. neighbors. In this case, functions of the spatial weight matrix become distance class dependent. For example, Moran's I is
This defines a type of spatial correlogram, in this case, since Moran's I measures spatial autocorrelation, measures how the autocorrelation of the data changes as a function of distance class. Remembering Tobler's first law of geography, "everything is related to everything else, but near things are more related than distant things" it usually decreases with distance.
Common distance functions include Euclidean distance, Manhattan distance and Great-circle distance.
Spatial Lag
One application of the spatial weight matrix is to compute the spatial lag
For row-standardised weights initially set to and with , is simply the average value observed at the neighbors of . These lagged variables can then be used in regression analysis to incorporate the dependence of the outcome variable on the values at neighboring sites.
The standard regression equation is
The spatial lag model adds the spatial lag vector to this
where is a parameter which controls the degree of autocorrelation of . This is similar to an autoregressive model in the analysis of time series.
See Also
Spatial Analysis
Moran's I
Geary's C
Join Count Statistics
Spatial analysis
Covariance and correlation
References | Spatial weight matrix | [
"Physics"
] | 780 | [
"Spacetime",
"Space",
"Spatial analysis"
] |
76,690,741 | https://en.wikipedia.org/wiki/Strict%20Fibonacci%20heap | In computer science, a strict Fibonacci heap is a priority queue data structure with low worst case time bounds. It matches the amortized time bounds of the Fibonacci heap in the worst case. To achieve these time bounds, strict Fibonacci heaps maintain several invariants by performing restoring transformations after every operation. These transformations can be done in constant time by using auxiliary data structures to track invariant violations, and the pigeonhole principle guarantees that these can be fixed. Strict Fibonacci heaps were invented in 2012 by Gerth S. Brodal, George Lagogiannis, and Robert E. Tarjan.
Along with Brodal queues, strict Fibonacci heaps belong to a class of asymptotically optimal data structures for priority queues. All operations on strict Fibonacci heaps run in worst case constant time except delete-min, which is necessarily logarithmic. This is optimal, because any priority queue can be used to sort a list of elements by performing insertions and delete-min operations. However, strict Fibonacci heaps are simpler than Brodal queues, which make use of dynamic arrays and redundant counters, whereas the strict Fibonacci heap is pointer based only.
Structure
A strict Fibonacci heap is a single tree satisfying the minimum-heap property. That is, the key of a node is always smaller than or equal to its children. As a direct consequence, the node with the minimum key always lies at the root.
Like ordinary Fibonacci heaps, strict Fibonacci heaps possess substructures similar to binomial heaps. To identify these structures, we label every node with one of two types. We thus introduce the following definitions and rules:
All nodes are either active (colored white) or passive (colored red).
An active root is an active node with a passive parent.
A passive linkable node is a passive node where all its descendants are passive (a passive node with no children is considered to be linkable).
The rank of an active node is the number of active children it has.
The loss of an active node is the number of active children it has lost.
For any node, the active children lie to the left of the passive children.
An active root always has zero loss.
The root is passive.
The passive linkable children of the root lie to the right of the passive non-linkable children.
Invariants
Invariant 1: Structure
The th rightmost active child of an active node satisfies .
Thus, the loss of an active node can be viewed as a generalisation of Fibonacci heap 'marks'. For example, a subtree consisting of only active nodes with loss zero is a binomial tree.
In addition, several invariants which impose logarithmic bounds on three main quantities: the number of active roots, the total loss, and the degrees of nodes. This is in contrast to the ordinary Fibonacci heap, which is more flexible and allows structural violations to grow on the order of to be cleaned up later, as it is a lazy data structure.
To assist in keeping the degrees of nodes logarithmic, every non-root node also participates in a queue . In the following section, and for rest of this article, we define the real number , where is the number of nodes in the heap, and denotes the binary logarithm.
Invariant 2: Active roots
The total number of active roots is at most .
Invariant 3: Total loss
The total loss in the heap is at most .
Invariant 4: Root degree
The degree of the root is at most .
Invariant 5: Non-root degrees
For an active node with zero loss, the degree is at most , where is its position in (with 1 as the first element). For all other non-root nodes, the degree is at most .
Corollary 1: Maximum degree
The degree of any non-root node is at most .
Proof:
This follows immediately from invariant 5. Letting , we have
Lemma 1: Maximum rank
If invariant 1 holds, the maximum rank or any active node is at most , where is the total loss.
Proof:
We proceed by contradiction. Let be an active node with maximal rank in a heap with nodes and total loss , and assume that , where is the smallest integer such that . Our goal is to show that the subtree rooted at contains nodes, which is a contradiction because there are only nodes in the heap.
Discard all subtrees rooted at passive nodes from , leaving it with only active nodes. Cut off all the grandchildren of whose subtrees contain any node of positive loss, and increase the loss of the children of accordingly, once for each grandchild lost. The quantity is unchanged for the remaining nodes, preserving invariant 1. Furthermore, the total loss is still at most .
The children of now consists of loss-free subtrees and leaf nodes with positive loss. Currently, satisfies for the th rightmost child of . We make this an exact equality by first reducing the loss of each , and pruning any grandchildren if necessary. Afterwards, exactly. All other descendants of are also converted into binomial subtrees by pruning children as necessary.
We now attempt to reconstruct a minimal version of by starting with a binomial tree of degree , containing active nodes. We wish to increase the loss to , but keep the rank of as and the number of nodes as low as possible. For a binomial tree of degree , there is one child of each degree from to . Hence, there are grandchildren of order . If we cut all the grandchildren whose degree , then we have cut grandchildren, which is sufficient to bring the loss up to . All grandchildren with degree survive. Let be the child of with degree and loss 0. By assumption, , and is a complete binomial tree, so it has at least nodes. Since this would mean has at least nodes, we have reached a contradiction, and therefore . Noting that , we obtain .
Corollary 2: Maximum rank
If invariants 1 and 3 both hold, then the maximum rank is .
Proof:
From invariant 3, we have . By substituting this into lemma 1, we calculate as follows:
Transformations
The following transformations restore the above invariants after a priority queue operation has been performed. There are three main quantities we wish to minimize: the number of active roots, the total loss in the heap, and the degree of the root. All transformations can be performed in time, which is possible by maintaining auxiliary data structures to track candidate nodes (described in the section on implementation).
Active root reduction
Let and be active roots with equal rank , and assume . Link as the leftmost child of and increase the rank of by 1. If the rightmost child of is passive, link to the root.
As a result, is no longer an active root, so the number of active roots decreases by 1. However, the degree of the root node may increase by 1,
Since becomes the th rightmost child of , and has rank , invariant 1 is preserved.
Lemma 2: Availability of active root reduction
If invariant 2 is violated, but invariants 1 and 3 hold, then active root reduction is possible.
Proof:
Because invariant 2 is broken, there are more than active roots present. From corollary 2, the maximum rank of a node is . By the pigeonhole principle, there exists a pair of active roots with the same rank.
Loss reduction
One node loss reduction
Let be an active non-root with loss at least 2. Link to the root, thus turning it into an active root, and resetting its loss to 0. Let the original parent of be . must be active, since otherwise would have previously been an active root, and thus could not have had positive loss. The rank of is decreased by 1. If is not an active root, increase its loss by 1.
Overall, the total loss decreases by 1 or 2. As a side effect, the root degree and number of active roots increase by 1, making it less preferable to two node loss reduction, but still a necessary operation.
Two node loss reduction
Let and be active nodes with equal rank and loss equal to 1, and let be the parent of . Without loss of generality, assume that . Detach from , and link to . Increase the rank of by 1 and reset the loss of and from 1 to 0.
must be active, since had positive loss and could not have been an active root. Hence, the rank of is decreased by 1. If is not an active root, increase its loss by 1.
Overall, the total loss decreases by either 1 or 2, with no side effects.
Lemma 3: Availability of loss reduction
If invariant 3 is violated by 1, but invariant 2 holds, then loss reduction is possible.
Proof: We apply the pigeonhole principle again. If invariant 3 is violated by 1, the total loss is . Lemma 1 can be reformulated to also work with . Thus, corollary 2 holds. Since the maximum rank is , either there either exists a pair of active nodes with equal rank and loss 1, or an active node with . Both cases present an opportunity for loss reduction.
Root degree reduction
Let , , and be the three rightmost passive linkable children of the root. Detach them all from the root and sort them such that . Change and to be active. Link to , link to , and link as the leftmost child of the root. As a result, becomes an active root with rank 1 and loss 0. The rank and loss of is set to 0.
The net change of this transformation is that the degree of the root node decreases by 2. As a side effect, the number of active roots increases by 1.
Lemma 4: Availability of root degree reduction
If invariant 4 is violated, but invariant 2 holds, then root degree reduction is possible.
Proof:
If invariant 4 is broken, then the degree of the root is at least . The children of the root fall into three categories: active roots, passive non-linkable nodes, and passive linkable nodes. Each passive non-linkable node subsumes an active root, since its subtree contains at least one active node. Because the number of active roots is at most , the rightmost three children of the root must therefore be passive linkable.
Summary
The following table summarises the effect of each transformation on the three important quantities. Individually, each transformation may violate invariants, but we are only interested in certain combinations of transformations which do not increase any of these quantities.
When deciding which transformations to perform, we consider only the worst case effect of these operations, for simplicity. The two types of loss reduction are also considered to be the same operation. As such, we define 'performing a loss reduction' to mean attempting each type of loss reduction in turn.
Implementation
Linking nodes
To ensure active nodes lie to the left of passive nodes, and preserve invariant 1, the linking operation should place active nodes on the left, and passive nodes on the right. It is necessary for active and passive nodes to coexist in the same list, because the merge operation changes all nodes in the smaller heap to be passive. If they existed in two separate lists, the lists would have to be concatenated, which cannot be done in constant time for all nodes.
For the root, we also pose the requirement that passive linkable children lie to the right of the passive non-linkable children. Since we wish to be able link nodes to the root in constant time, a pointer to the first passive linkable child of the root must be maintained.
Finding candidate nodes
The invariant restoring transformations rely on being able to find candidate nodes in time. This means that we must keep track of active roots with the same rank, nodes with loss 1 of the same rank, and nodes with loss at least 2.
The original paper by Brodal et al. described a fix-list and a rank-list as a way of tracking candidate nodes.
Fix-list
The fix-list is divided into four parts:
Active roots ready for active root reduction – active roots with a partner of the same rank. Nodes with the same rank are kept adjacent.
Active roots not yet ready for active reduction – the only active roots for that rank.
Active nodes with loss 1 that are not yet ready for loss reduction – the only active nodes with loss 1 for that rank.
Active nodes that are ready for loss reduction – This includes active nodes with loss 1 that have a partner of the same rank, and active nodes with loss at least 2, which do not need partners to be reduced. Nodes with the same rank are kept adjacent.
To check if active root reduction is possible, we simply check if part 1 is non-empty. If it is non-empty, the first two nodes can be popped off and transformed. Similarly, to check if loss reduction is possible, we check the end of part 4. If it contains a node with loss at least 2, one node loss reduction is performed. Otherwise, if the last two nodes both have loss 1, and are of the same rank, two node loss reduction is performed.
Rank-list
The rank-list is a doubly linked list containing information about each rank, to allow nodes of the same rank to be partnered together in the fix-list.
For each node representing rank in the rank-list, we maintain:
A pointer to the first active root in the fix-list with rank . If such a node does not exist, this is NULL.
A pointer to the first active node in the fix-list with rank and loss 1. If such a node does not exist, this is NULL.
A pointer to the node representing rank and , to facilitate the incrementation and decrementation of ranks.
The fix-list and rank-list require extensive bookkeeping, which must be done whenever a new active node arises, or when the rank or loss of a node is changed.
Shared flag
The merge operation changes all of the active nodes of the smaller heap into passive nodes. This can be done in time by introducing a level of indirection. Instead of a boolean flag, each active node has a pointer towards an active flag object containing a boolean value. For passive nodes, it does not matter which active flag object they point to, as long as the flag object is set to passive, because it is not required to change many passive nodes into active nodes simultaneously.
Storing keys
The decrease-key operation requires a reference to the node we wish to decrease the key of. However, the decrease-key operation itself sometimes swaps the key of a node and the key root.
Assume that the insert operation returns some opaque reference that we can call decrease-key on, as part of the public API. If these references are internal heap nodes, then by swapping keys we have mutated these references, causing other references to become undefined. To ensure a key is always stays with the same reference, it is necessary to 'box' the key. Each heap node now contains a pointer to a box containing a key, and the box also has a pointer to the heap node. When inserting an item, we create a box to store the key in, link the heap node to the box both ways, and return the box object. To swap the keys between two nodes, we re-link the pointers between the boxes and nodes instead.
Operations
Merge
Let and be strict Fibonacci heaps. If either is empty, return the other. Otherwise, let and be their corresponding sizes. Without loss of generality, assume that . Since the sizes of the fix-list and rank-list of each heap are logarithmic with respect to the heap size, it is not possible to merge these auxiliary structures in constant time. Instead, we throw away the structure of the smaller heap by discarding its fix-list and rank-list, and converting all of its nodes into passive nodes. This can be done in constant time, using a shared flag, as shown above. Link and , letting the root with the smaller key become the parent of the other. Let and be the queues of and respectively. The queue of resulting heap is set to, where is the root with the larger key.
The only possible structural violation is the root degree. This is solved by performing 1 active root reduction, and 1 root degree reduction, if each transformation is possible.
Proof of correctness
Invariants 1, 2, and 3 hold automatically, since the structure of the heap is discarded. As calculated above, any violations of invariant 4 are solved by the root degree reduction transformation.
To verify invariant 5, we consider the final positions of nodes in . Each node has its degree bounded by or .
For the smaller heap the positions in are unchanged. However, all nodes in are now passive, which means that their constraint may change from the case to the case. But noting that , the resulting size is at least double . This results in an increase of at least 1 on each constraint, which eliminates the previous concern.
The root with the larger key between and becomes a non-root, and is placed between and at position . By invariant 4, its degree was bounded by either or , depending on which heap it came from. It is easy to see that this is less than in any case.
For the larger heap, the positions increase by . But since the resulting size is , the value actually increases, weakening the constraint.
Insert
Insertion can be considered a special case of the merge operation. To insert a single key, create a new heap containing a single passive node and an empty queue, and merge it with the main heap.
Find-min
Due to the minimum-heap property, the node with the minimum key is always at the root, if it exists.
Delete-min
If the root is the only node in the heap, we are done by simply removing it. Otherwise, search the children of the root to find the node with minimum key, and set the new root to . If is active, make it passive, causing all active children of to implicitly become active roots. Link the children of the old root to . Since is now the root, move all of its passive linkable children to the right, and remove from .
The degree of the root approximately doubles, because we have linked all the children of the old root to . We perform the following restorative transformations:
Repeat twice: rotate by moving the head of to the back, and link the two rightmost passive children of to the root.
If a loss reduction is possible, perform it.
Perform active root reductions and root degree reductions until neither is possible.
To see how step 3 is bounded, consider the state after step 3:
Observe that, 3 active root reductions and 2 root reductions decreases the root degree and active roots by 1:
Since , step 3 never executes more than times.
Proof of correctness
Invariant 1 holds trivially, since no active roots are created.
The size of the heap decreases by one, causing decreases by at most one. Thus, invariant 3 is violated by at most 1. By lemma 3, loss reduction is possible, which has been done by step 2.
Invariants 1 and 3 now hold. If invariants 2 and 4 were still violated after step 3, it would be possible to apply active root reduction and root degree reduction, by lemmas 2 and 4. However, active root reduction and root degree reduction have already been exhaustively applied. Therefore, invariants 2 and 4 also hold.
To show that invariant 5 is satisfied, we first note that the heap size has decreased by 1. Because the first 2 nodes in are popped in step 1, the positions of the other elements in decrease by 2. Therefore, the degree constraints and remain constant for these nodes. The two nodes which were popped previously had positions 1 and 2 in , and now have positions and respectively. The effect is that their degree constraints have strengthened by 2, however, we cut off two passive children for each of these nodes, which is sufficient to satisfy the constraint again.
Decrease-key
Let be the node whose key has been decreased. If is the root, we are done. Otherwise, detach the subtree rooted at , and link it to the root. If the key of is smaller than the key of the root, swap their keys.
Up to three structural violations may have occurred. Unless was already a child of the root, the degree of the root increases by 1. When was detached from its original parent , we have the following cases:
If is passive, then there are no extra violations.
If was previously an active root with passive, then moving from being a child of to a child of the root does not create any additional active roots, nor does it increase the loss of any node.
If both and are active, then the loss of increases by 1, and an extra active root is created (by linking to the root).
In the worst case, all three quantities (root degree, total loss, active roots) increase by 1.
After performing 1 loss reduction, the worst case result is still that the root degree and number of active roots have both increased by 2. To fix these violations, we use the fact that 3 active root reductions and 2 root reductions decrease both of these quantities by 1. Hence, applying these transformations 6 and 4 times respectively is sufficient to eliminate all violations.
Proof of correctness
The nodes which were previously the left siblings of move to fill the gap left by , decreasing their index. Since their constraint has weakened, invariant 1 is unaffected. Invariant 5 trivially holds as is unchanged.
Lemmas 2, 3 and 4 guarantee the availability of active root reduction, loss reduction, and root degree reduction. Therefore, invariants 2, 3 and 4 hold.
Performance
Although theoretically optimal, strict Fibonacci heaps are not useful in practical applications. They are extremely complicated to implement, requiring management of more than 10 pointers per node. While most operations run in time, the constant factors may be very high, making them up to 20 times slower than their more common counterparts such as binary heaps or pairing heaps. Despite being relatively simpler, experiments show that in practice the strict Fibonacci heap performs slower than the Brodal queue.
Summary of running times
References
External links
JavaScript simulation of strict Fibonacci heap
Fibonacci numbers
Heaps (data structures) | Strict Fibonacci heap | [
"Mathematics"
] | 4,598 | [
"Fibonacci numbers",
"Mathematical relations",
"Golden ratio",
"Recurrence relations"
] |
63,589,365 | https://en.wikipedia.org/wiki/Archaeal%20translation | Archaeal translation is the process by which messenger RNA is translated into proteins in archaea. Not much is known on this subject, but on the protein level it seems to resemble eukaryotic translation.
Most of the initiation, elongation, and termination factors in archaea have homologs in eukaryotes. Shine-Dalgarno sequences only are found in a minority of genes for many phyla, with many leaderless mRNAs probably initiated by scanning. The process of ABCE1 ATPase-based recycling is also shared with eukaryotes.
Being a prokaryote without a nucleus, archaea do perform transcription and translation at the same time like bacteria do.
References
Further reading
Molecular biology
Protein biosynthesis
Gene expression | Archaeal translation | [
"Chemistry",
"Biology"
] | 156 | [
"Protein biosynthesis",
"Gene expression",
"Molecular biology stubs",
"Molecular genetics",
"Biosynthesis",
"Cellular processes",
"Molecular biology",
"Biochemistry"
] |
63,589,689 | https://en.wikipedia.org/wiki/Archaeal%20transcription | Archaeal transcription is the process in which a segment of archaeal DNA is copied into a newly synthesized strand of RNA using the sole Pol II-like RNA polymerase (RNAP). The process occurs in three main steps: initiation, elongation, and termination; and the end result is a strand of RNA that is complementary to a single strand of DNA. A number of transcription factors govern this process with homologs in both bacteria and eukaryotes, with the core machinery more similar to eukaryotic transcription.
Because archaea lack a membrane-enclosed nucleus like bacteria do, transcription and translation can happen at the same time on a newly-generated piece of mRNA. Operons are widespread in archaea.
Initiation
Initiation in archaea is governed by TATA-binding protein (TBP), Archaeal transcription factor B (TFB), and Archaeal transcription factor E (TFE) that are homologous to eukaryotic TBP, TFIIB, and TFIIE respectively. These factors recognize the promoter core sequence (TATA box, B recognition element) upstream of the coding region and recruits the RNAP to form a closed transcription preinitiation complex (PIC).
The PIC is turned into an open state with the local DNA helix "melting" to load the template strand of DNA. The RNAP undergoes "abortive initiation": it makes and releases many short (2-15nt) segments before generating a transcript of significant length. This continues until it moves past the promoter (promoter escape), loosening TBP's grasp on the DNA, and swapping TFE out for elongation factors Spt4/5. How this escape happens exactly remains to be studied.
Elongation
After getting out of the promoter region, the RNAP moves into the elongation state, where it keeps growing the new RNA strand in a processive process. Double stranded DNA that enters from the front of the enzyme is unzipped to avail the template strand for RNA synthesis. For every DNA base pair separated by the advancing polymerase, one hybrid RNA:DNA base pair is immediately formed. DNA strands and nascent RNA chain exit from separate channels; the two DNA strands reunite at the trailing end of the transcription bubble while the single strand RNA emerges alone.
A number of elongation factors help with the rate and processivity of the RNAP. Factors of the Spt4/Spt5 family (bacterial homolog of Spt5 is called NusG) stimulate transcription by binding to the RNAP clamp on one side of the DNA channel and to the gate loop on the other. The resultant DSIF locks the clamp into a closed state to prevent the elongation complex (EC) from dissociating. Spt5 also has a NGN domain that helps the two strands separate. A KOW domain probably hooks the RNAP up to a ribosome so that translation and transcription happen together.
Some archaea have an Elf1 homolog that might also act as an elongation factor.
Backtracking
The RNAP occasionally stops and starts moving backwards when it encounters a roadblock or some difficult sequences. When this happens, the EC gets stuck because the reactive 3' edge of the RNA is out of the active site. The transcript cleavage factor TFS (a TFIIS homolog) helps resolve this issue by generating a cut so that a new 3' end is available in the active site. Some archaeon have up to 4 paralogs of TFS with divergent functions.
Termination
Not much is known about archaeal termination. Euryarchaeal RNAPs seem to terminate on their own when poly-U stretches appear.
References
Gene expression
Archaea | Archaeal transcription | [
"Chemistry",
"Biology"
] | 770 | [
"Archaea",
"Gene expression",
"Prokaryotes",
"Molecular genetics",
"Cellular processes",
"Molecular biology",
"Biochemistry",
"Microorganisms"
] |
63,591,386 | https://en.wikipedia.org/wiki/Olamkicept | Olamkicept, also known as soluble gp130Fc or sgp130Fc (other designations are FE 999301, FE301, TJ301) is an immunosuppressive drug candidate, which selectively blocks activities of the cytokine Interleukin-6, which are mediated by the soluble Interleukin-6. Interleukin-6 is a cytokine, which plays a dominant role in the regulation of the immune response and also in autoimmunity. Furthermore, Interleukin-6 has been demonstrated to be involved in the regulation of metabolism and body weight. Interleukin-6 also has many activities on neural cells. The biochemical principle was invented by the German biochemist Stefan Rose-John and it was further developed into a biotech compound by the Conaris Research Institute AG, which gave an exclusive world-wide license to the Swiss-based biopharmaceutical company Ferring Pharmaceuticals. In December 2016, Ferring and the biotech company I-MAB signed a licensing agreement granting I-MAB exclusive rights in Asia to Olamkicept for the treatment of autoimmune disease.
Mechanism of action
On cells, interleukin-6 binds to an Interleukin-6 receptor, which, however, is not signaling. The complex of Interleukin-6 and the Interleukin-6 receptor binds to a second receptor protein, gp130, which thereupon dimerizes and initiates intracellular signaling. The gp130 receptor is present on all cells of the human body, whereas the Interleukin-6 receptor is only expressed by some cells such as hepatocytes, epithelial cells and some leukocytes. Since Interleukin-6 exhibits only measurable affinity to the Interleukin-6 receptor but not to gp130, only cells, which express the Interleukin-6 receptor can respond to Interleukin-6. It was found that the Interleukin-6 receptor can be cleaved from the cell membrane by the protease ADAM17 generating a soluble receptor. The soluble interleukin-6 receptor can still bind interleukin-6 and the complex of interleukin-6 and interleukin-6 receptor can bind to gp130 even on cells which do not express the membrane-bound interleukin-6 receptor. This mode of signaling has named Interleukin-6 trans-signaling. The protein olamkicept consists of the extracellular portion of gp130 fused (and thereby dimerized) to the constant portion of a human IgG1 antibody. Like membrane bound gp130, the protein olamkicept does not bind Interleukin-6 alone but only the complex of interleukin-6 and soluble interleukin-6 receptor. Therefore, olamkicept only inhibits interleukin-6 trans-signaling but not interleukin-6 signaling via the membrane-bound interleukin-6 receptor. It has been shown that Interleukin-6 activities via the membrane-bound interleukin-6 receptor are regenerative and protect from bacterial infections whereas interleukin-6 activities via the soluble interleukin-6 receptor are considered pro-inflammatory. Therefore, olamkicept only blocks the pro-inflammatory activities of the cytokine interleukin-6.
Research
In many animal disease models of human pathologies it was tested whether the specific blockade of interleukin-6 trans-signaling by the olamkicept protein was superior to a global blockade with an interleukin-6 or an interleukin-6 receptor neutralizing antibody. It turned out that the specific blockade of Interleukin-6 trans-signaling was superior to global Interleukin-6 blockade in models of e.g. sepsis, of acute lung injury after severe acute pancreatitis and of abdominal aortic aneurysm. Furthermore, it was shown that Interleukin-6 trans-signaling plays a dominant role in colon cancer and lung cancer.
Medical use
The olamkicept protein underwent phase I clinical studies in healthy volunteers and a small cohort of largely inactive patients with IBD in 2013/14. An open label phase IIa study in patients with active inflammatory bowel disesase was performed in Germany. A second placebo-controlled, phase II clinical trial in patients with ulcerative colitis was successfully completed in China, Taiwan and South Korea. The results of the German phase IIa clinical trial were published and demonstrated target engagement through olamkicept exposure over 12 weeks in patients with active inflammatory bowel disease. Most interestingly some patients developed a complete remission while others went into response. The molecular analysis revealed an olamkicept-specific signature in influencing disease pathophysiology. The results of the placebo controlled trial in China/Taiwan/South Korea were released during the 2021 Digestive Disease Week (DDW) and the 2021 annual meeting of the European Crohn’s and Colitis Organization (ECCO).
References
Recombinant proteins | Olamkicept | [
"Biology"
] | 1,088 | [
"Recombinant proteins",
"Biotechnology products"
] |
63,591,823 | https://en.wikipedia.org/wiki/Simen%20%C3%85dn%C3%B8y%20Ellingsen | Simen Andreas Ådnøy Ellingsen (born 14 May 1981) is a Norwegian engineering physicist specializing in fluid mechanics, especially waves, turbulence, and quantum mechanics. He is a full professor at the Norwegian University of Science and Technology, at the Department of Energy and Process Engineering. He is known for having expanded Lord Kelvin's work known as Kelvinangle. He received the Royal Norwegian Society of Sciences and Letters Prize for Young Researchers in the Natural Sciences in 2011 and became a member of the Young Academy of Norway in 2019. He received a European Research Council Consolidator Grant in 2022.
He plays several instruments and has published music with the band Shamblemaths.
Education
Ellingsen has two doctoral degrees. The first from 2009 is Nuclear Terrorism and Rational Choice from King's College London. The second from 2011 is Dispersion forces in Micromechanics: Casimir and Casimir-Polder forces affected by geometry and non-zero temperature from the Norwegian University of Science and Technology.
Publications (selection)
(The Norwegian Scientific Index)
Membership and honours
In 2011 he was the winner of the Royal Norwegian Society of Sciences and Letters Prize for Young Researchers in the Natural Sciences.
Ellingsen became one of 12 new members of the Young Academy of Norway in 2019, and is member of the Royal Norwegian Society of Sciences and Letters.
References
External links
Home page
1981 births
Engineering academics
Engineering educators
Fluid dynamicists
Living people
Norwegian physicists
Academic staff of the Norwegian University of Science and Technology
Quantum physicists
Royal Norwegian Society of Sciences and Letters | Simen Ådnøy Ellingsen | [
"Physics",
"Chemistry"
] | 312 | [
"Fluid dynamicists",
"Quantum physicists",
"Quantum mechanics",
"Fluid dynamics"
] |
63,591,893 | https://en.wikipedia.org/wiki/Sex%20trafficking%20in%20Malaysia | Sex trafficking in Malaysia is human trafficking for the purpose of sexual exploitation and slavery that occurs in Malaysia. Malaysia is a country of origin, destination and transit for sex trafficking.
Sex trafficking victims in the country are from all ethnic groups in Malaysia and foreigners. Children, people in rural areas and or poverty, minorities, migrants, and refugees are vulnerable. Malaysian citizens, primarily women and girls, have been sex trafficked into other countries in Asia and different continents. Many are forced into prostitution and or marriage and unfree labour. Victims are threatened and experience physically and psychologically abuse. They contract sexually transmitted diseases from rapes. Some are coerced to be in online pornographic films. The perpetrators are often part of or collude with criminal syndicates. They increasing use the internet to deceive victims.
The government of Malaysia has been criticized for its response to sex trafficking. Corruption and impunity are pervasive. Officials and police have been complicit in trafficking. Law enforcement have also failed to recognize victims and other indications of trafficking, and have treated cases as immigration violations. Though some anti-trafficking efforts, such as public service announcements, are carried out, progress has been limited by poor border management, weak victim protections, inadequate law enforcement practices, low convictions, and other factors.
See also
Human rights in Malaysia
Human trafficking in Malaysia
Slavery in Malaysia
References
Prostitution in Malaysia
Women in Malaysia
Malaysian women
Youth in Malaysia
Society of Malaysia
Human rights abuses in Malaysia
Malaysia | Sex trafficking in Malaysia | [
"Biology"
] | 298 | [
"Behavior",
"Sexuality stubs",
"Sexuality"
] |
63,591,906 | https://en.wikipedia.org/wiki/NGC%20635 | NGC 635 is a spiral galaxy located in the constellation of Cetus about 626 million light years from the Milky Way. NGC 635 was discovered by the American astronomer Francis Leavenworth in 1885. It is also known as MCG-04-05-002 or PGC 6062, although in SIMBAD its New General Catalogue designation is not recognized.
See also
List of NGC objects (1–1000)
References
Spiral galaxies
Cetus
0635
006062 | NGC 635 | [
"Astronomy"
] | 99 | [
"Cetus",
"Constellations"
] |
63,591,986 | https://en.wikipedia.org/wiki/NGC%20636 | NGC 636 is an elliptical galaxy in the Cetus constellation. It is located about 96 million light-years from the Milky Way. It was discovered by the German–British astronomer William Herschel in 1785.
See also
List of NGC objects (1–1000)
References
External links
Elliptical galaxies
0636
Cetus
006110 | NGC 636 | [
"Astronomy"
] | 68 | [
"Cetus",
"Constellations"
] |
63,592,266 | https://en.wikipedia.org/wiki/Oman%E2%80%93United%20Arab%20Emirates%20border | The Oman–United Arab Emirates border consists of three non-contiguous sections totalling 609 km (378 mi) in length.
Description
Northern (Musandam) section
The northern section of the border divides the Omani exclave of Musandam from the UAE Emirates of Fujairah and Ras Al Khaimah. This peninsula commands the strategic Strait of Hormuz, with the Oman-UAE border consisting of a series of irregular, though roughly horizontal, lines running through mountainous terrain, from the western Persian Gulf coast to the eastern Gulf of Oman coast.
Middle (enclaved) section
The middle section of the border consists of the Omani enclave of Madha, within which is the UAE counter-enclave of Nahwa, belonging to the Emirate of Sharjah. This territory is the only territory between UAE and Oman which is not lined with any barrier and there is no border crossing between Madha, Nahwa, or the rest of the UAE.
Southern section
The southern, and by far the longest, section of the frontier starts in the north on the Oman Gulf coast, just south of Kalba in the Emirate of Sharjah. It then proceeds inland roughly south-westwards via a series of irregular lines, arcing southwards so as to include Hatta within the UAE. The border then proceeds roughly south-westwards down to the Omani tripoint, save for a piece of Emirati territory south-east of Al-Ain that juts into Oman.
History
During the 19th century, Britain had signed a number of protectorate treaties with seven emirates on what was then known as the 'Pirate Coast', giving rise to the so-called Trucial States. Britain also exercised protectorate control over Oman via its sultan. Boundaries in this part of Arabia remained indistinct; Britain and the Ottoman Empire theoretically divided their realms of influence in Arabia via the so-called 'Blue' and 'Violet lines' in 1913–14, however these agreements were rendered null and void following the collapse of the Ottoman Empire after the First World War.
The enclaves of Madha and Nahwa appear to have arisen in the 1930s-40, following a dispute over the ownership of the area between Oman and the local emirs, which was settled by a vote amongst the village elders. The boundaries of the enclaves were fixed in 1969.
In the 1950s Britain appointed Julian Walker to survey more precise boundaries between the Trucial States and Oman. However, by the time of independence of the Trucial States (as the United Arab Emirates) in 1971, much of the border remained undemarcated, resulting in several disputes. The Ras Al Khaimah section of the boundary was settled in 1979 after a dispute arose in 1977-78 following the discovery of oil in the area. Relations between the two states warmed in the 1980s-90s, resulting in a border agreement for the southern section of the frontier in 1999, followed by a complete border delimitation ratified in Abu Dhabi on 22 June 2002.
Barrier
In 2002, the UAE announced that it was installing a fence along the UAE-Oman border (minus the Madha-Nahwa enclaves) in an effort to curb the flow of illegal migrants, illicit drugs and terrorists into the country. The barrier constructed is a 4-meter barbed wire border fence.
In 2003, Oman introduced an exit toll on crossing to the UAE border. In July 2004, Oman and the UAE jointly launched a three-day coordinated crackdown in and around Al Buraimi and arrested approximately 1,000 illegal immigrants.
Settlements near the border
Oman
Tibat
Quroon as Said
Dibba Al-Baya
Al Wajajah
Aswad
A'Tuvayah
Hadf
Al-Buraimi
Mahdah
Hamasa
Al Qabil
Sahl al Arba
Safah
Al Khuwayr
United Arab Emirates
Sha'am
Al Jeer
Dibba Al-Fujairah
Dibba Al-Hisn
Shis
Qidfa
Sayh Mudayrah
Mirbah
Wahla
Al Nasla
Mosfuj
Al Qor
Fili
Al Madam
Shwaib
Al Ain
Al Ghafan
Mezyad
Al Arad
Al Qua’a
Umm az Zamul
Border Crossings
There are two border crossings on the Musandam section of the border (Tibat and Dibba) and four on the main southern section (Hatta/Al Wajajah, Hilli, Jebel Hafeet and Khatmat Malaha). There are no border controls at the Madha-Nahwa enclaves.
Gallery
See also
Oman-United Arab Emirates relations
References
Borders of Oman
Borders of the United Arab Emirates
International borders
Border barriers | Oman–United Arab Emirates border | [
"Engineering"
] | 950 | [
"Separation barriers",
"Border barriers"
] |
63,592,402 | https://en.wikipedia.org/wiki/Ferulic%20acid%20decarboxylase | Ferulic acid decarboxylases (Fdc) are decarboxylase enzymes capable of the reversible decarboxylation of aromatic carboxylic acids such as ferulic acid and cinnamic acid. Fdc's are fungal homologues of the E.coli UbiD enzyme which is involved in ubiquinone biosynthesis. This places Fdc within the wider UbiD enzyme family, representing a distinct clade within the family
Presence of fdc1 and the associated pad1 genes (Pad1 homologous to UbiX in E.coli) were shown to be required for the decarboxylation of phenylacrylic acids in Saccharomyces cerevisiae.
In 2015 the cofactor prFMN was discovered in the active site of Fdc1 from Aspergillus niger (AnFdc) by crystallography, prior to this genetic studies had led to the assumption that both UbiD and UbiX encoded isofunctional decarboxylases. In actuality UbiX/Pad were found to be flavin preyltransferases supplying the prFMN cofactor to UbiD/Fdc where it is utilised for the reversible decarboxylation of alpha-beta unsaturated carboxylic acid substrates. Since the discovery of prFMN AnFDC has become the most well understood representative of the UbiD enzyme family
AnFDC Mechanism
In the same paper in which the structure of prFMN was deduced in the active site of AnFdc1 there was a proposal for the mechanism by which Fdc1 decarboxylates α,β-unsaturated carboxylic acids. Not all UbiD enzymes decarboxylate acrylic acid substrates and other mechanisms may be at play for alternative substrates. In the case of AnFdc1 it was noted that prFMN displays an azomethine ylide characteristic C4a-N5+=C1’(Figure 1). This is a well-known 1,3-dipole in organic chemistry, positioned in the enzyme active site near to the α,β-unsaturated carboxylic acid substrate which contains a 1,3-dipolarophile. Thus, it was proposed that a 1,3-dipolar cycloaddition mechanism was responsible for the enzymatic decarboxylation. This was confirmed in a later paper.
The mechanism proposed in for 1,3-dipolar cycloaddition by Fdc1 is as follows (intermediates represented in Figure 1):
1,3-dipolar cycloaddition between prFMNiminium and the α,β-unsaturated substrate leads to a pyrrolidine cycloadduct (Int1)
This pyrrolidine cycloadduct supports simultaneous decarboxylation and ring opening, resulting in the formation of a distinct prFMN-alkene adduct (Int2)
A conserved glutamic acid residue (E282) donates a proton to the alkene moiety, resulting a second pyrrolidine cycloadduct (Int3)
The reaction concludes with cycloelimination of Int3 and the release of the alkene product and CO2
A study went on to present evidence for the 1,3-dipolar cycloaddition, due to suspected turnover of cinnamic acid a crystal structure of AnFdc1 in complex with α-fluorocinnamic acid revealed the substrate Cα and Cβ carbons are located directly above the prFMNiminium C1’ and C4a respectively (shown as Sub in Figure 1 - with cinnamic acid as opposed to α-fluorocinnamic acid). Cinnamic acid was confirmed to bind in a similar manner using inactive AnFdc1 crystals containing FMN. The AnFdc1 E282Q mutant crystallised with cinnamic acid revealed a structure corresponding to the Int2 species, this was taken to mean that progression through the 1,3-dipolarcycloadition cycle was halted as E282 is unable to donate a proton to the alkene moiety.
In order to observe the Int1 and Int3 structures alkyne analogues were used. Like alkenes these compounds can also act as dipolarophiles but cycloaddition would yield a cycloadduct containing a double bond. An inactive AnFdc1 enzyme (with prFMNradical bound) co-crystallised with the phenylpropiolic acid revealed binding in a similar manner to the α-fluorocinnamic acid AnFdc1 and cinnamic acid AnFdc1 with FMN bound (Inhib). An active AnFdc1 enzyme co-crystallised with phenylpropiolic acid revealed clear density for a 3-pyrroline cycloadduct (Int3’) between the alkyne and prFMNiminium. Int3’ represents a structure post decarboxylation, so it was assumed that over the time it took for crystallisation (~24h) the decarboxylation had occurred. Using a rapid soaking procedure, a different cycloadduct was observed that retained the carboxyl moiety (Int1’).
References
Enzymes
Acids
Biochemistry
Fungal proteins | Ferulic acid decarboxylase | [
"Chemistry",
"Biology"
] | 1,162 | [
"Biochemistry",
"Acids",
"nan"
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.