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58,041,927 | https://en.wikipedia.org/wiki/NGC%203873 | NGC 3873 is an elliptical galaxy located about 300 million light-years away in the constellation Leo. The galaxy was discovered by astronomer Heinrich d'Arrest on May 8, 1864. NGC 3873 is a member of the Leo Cluster.
On May 15, 2007 a type Ia supernova designated as SN 2007ci was discovered in NGC 3873.
See also
NGC 3842
References
External links
3873
36670
Leo (constellation)
Leo Cluster
Astronomical objects discovered in 1864
Elliptical galaxies
6735 | NGC 3873 | [
"Astronomy"
] | 104 | [
"Leo (constellation)",
"Constellations"
] |
58,042,061 | https://en.wikipedia.org/wiki/WatchGuard | WatchGuard, formally known as WatchGuard Technologies, Inc, is an American technology company based in Seattle, Washington. It specializes in network security solutions aimed at safeguarding computer networks from external threats such as malware and ransomware.
The company was founded in 1996.
History
WatchGuard was initially established in 1996 under the name Seattle Software Labs, Inc. Its inaugural product was a network firewall known as the WatchGuard Security Management System, which included the WatchGuard Firebox, a "firewall in a box" security appliance, along with configuration and administration software.
In 1997, the company rebranded itself as WatchGuard Technologies, Inc.
Come July 1999, WatchGuard Technologies, Inc. went public, trading on Nasdaq.
In October 2006, the company was acquired for $151 million by private equity firms Francisco Partners and Vector Capital. Bruce Coleman assumed the role of interim CEO.
In August 2007, Joe Wang took over as the company's permanent CEO, succeeding Coleman.
In May 2014, CEO Wang stepped down, and interim CEO Michael Kohlsdorf, an operating partner with Francisco Partners, assumed leadership.
In April 2015, Kohlsdorf passed the CEO mantle to Prakash Panjwani. It was announced that both Panjwani and Kohlsdorf were joining WatchGuard's board.
In June 2016, the company acquired HawkEye G, a threat-detection and response technology from Hexis Cyber Solutions, now part of KEYW Holding Corp. In October, the company launched the WatchGuard Wi-Fi Cloud to expand its network security coverage to Wi-Fi networks.
In August 2017, WatchGuard acquired Datablink, a provider of multi-factor authentication software used to secure laptops, servers, and other devices.
In January 2018, the company acquired Percipient Networks, a domain name system security service provider. Later it was renamed as DNSWatch.
In July 2018, the company unveiled AuthPoint, an application designed to offer multi-factor authentication security for businesses.
In March 2020, WatchGuard announced an agreement to acquire Bilbao-based Panda Security, a provider of network endpoint security. The deal was finalized in June.
Products
The company develops security products and services for businesses. There are four product groups: Network Security, Endpoint Security, Secure Wi-Fi, and Multi-Factor Authentication.
The Network Security devices are categorized as Unified Threat Management (UTM), where a single device provides multiple security features. The devices include WatchGuard Dimension, a network discovery tool that allows administrators to identify devices on the network, including mobile devices; and WatchGuard Cloud, giving the devices access to online threat intelligence.
The Endpoint Security offering includes products and services that provide advanced endpoint security, endpoint antivirus, security operations, and DNS-level protection and content filtering.
The Secure Wi-Fi product line consists of secure indoor and outdoor Wave 1 and Wave 2 802.11ac Wi-Fi hardware, security subscription services, and WatchGuard's Wi-Fi Cloud, a management platform used to control the devices.
The Multi-Factor Authentication group includes the company's AuthPoint application, a multi-factor authentication management and reporting tool that prevents unauthorized users from accessing sensitive cloud applications, VPNs, and networks.
The company also issues a quarterly security report based on feed data from WatchGuard UTM appliances installed at customer sites. The report highlights the type and frequency of malicious attacks occurring on computer networks.
References
External links
Official website
Computer security companies
Companies based in Seattle
American companies established in 1996
Networking hardware companies
Networking companies of the United States
Privately held companies based in Washington (state)
Computer companies of the United States
Computer hardware companies | WatchGuard | [
"Technology"
] | 748 | [
"Computer hardware companies",
"Computers"
] |
58,042,122 | https://en.wikipedia.org/wiki/Tetramethylphosphonium%20bromide | Tetramethylphosphonium bromide is an organophosphorus compound with the formula (CH3)4PBr. It is a white, water-soluble solid, the salt of the cation tetramethylphosphonium and the bromide anion. It is prepared by treating trimethylphosphine with methyl bromide.
Reactions
Deprotonation gives methylenetrimethylphosphine ylide, which can sustain a second deprotonation:
(CH3)4PBr + BuLi → CH3)3P=CH2 + LiBr + BuH
CH3)3P=CH2 + BuLi → CH3)2P(CH2)2Li + BuH
The latter is a precursor to many coordination complexes, e.g., the dicuprous complex Cu2[(Me2P(CH2)2]2.
References
Quaternary phosphonium compounds
Bromides
Organophosphorus compounds | Tetramethylphosphonium bromide | [
"Chemistry"
] | 209 | [
"Functional groups",
"Salts",
"Organic compounds",
"Bromides",
"Organophosphorus compounds"
] |
58,042,232 | https://en.wikipedia.org/wiki/1995%20University%20of%20Maryland%20conference%20on%20crime%20and%20genetics | The University of Maryland hosted a 1995 conference to examine and discuss the relationship between genetics and crime. It took place from September 22 to 24 at the Aspen Institute in Queenstown, Maryland. It was originally planned for 1992, but was effectively cancelled after the original proposal was met with fierce backlash and accusations of racism.
Background
Originally planned 1992 conference
In 1992, UMD professor David Wasserman set out to organize a meeting to discuss the potential genetic bases for criminal behavior. The originally planned conference was entitled "Genetic Factors in Crime: Findings, Uses and Implications", and was scheduled to be held on the University of Maryland's College Park campus on October 9, 1992. It was to be funded by a $78,000 grant from the National Institutes of Health (NIH).
When the planned conference became known to the public, it faced swift backlash and condemnation from civil rights activists, as well as from Peter Breggin, a prominent critic of psychiatry. Breggin's claim that the conference was racist had attracted the attention of the Congressional Black Caucus, which subsequently joined Breggin in protesting the conference, as did the Association of Black Psychologists and the NAACP's Baltimore chapter. Wasserman responded to the conference's critics by saying that the conference would aim to critically examine, not promote, research linking genes to crime, but this did not satisfy its critics. The backlash to Alcohol, Drug Abuse, and Mental Health Administration then-director Frederick K. Goodwin's controversial statement earlier that year, which compared inner cities in the United States to "jungles", inspired further opposition. Breggin had publicly linked the planned conference both to Goodwin's remarks and to an anti-violence initiative that had recently been proposed by then-Secretary of Health and Human Services Louis Wade Sullivan.
In July 1992, the NIH's National Center for Human Genome Research revoked the $78,000 grant that it had already given in response to the opposition, effectively cancelling it. That September, the NIH announced that it would be postponing the conference indefinitely, putting an end to the organizers' attempts to convince the NIH to reinstate the grant. In defending their decision to revoke the conference grant, it also cited a brochure promoting the conference and claimed that the brochure implied, falsely, that the NIH itself believed that there was a definitive link between genetics and crime. John W. Diggs, the NIH's then-deputy director for outside research, told the New York Times that the brochure suggested as scientific facts the link between genetics and crime and the potential for genetic tests to identify people predisposed to criminal behavior. Diggs further said that these statements "inflamed public opinion" and deviated significantly from the scope of the original grant proposal.
The University of Maryland responded to the cancellation by claiming that the NIH's withdrawal of the grant was a violation of the University's academic freedom and appealed the NIH's decision to cancel the conference. The appeal succeeded, and NIH funded the conference again, this time with a $133,000 grant. The NIH's new grant was awarded after Wasserman broadened the scope of topics to be covered in the conference, as well as allowing for more discussion on the desirability and potential implications of the research. This broader scope was reflected in the conference's new name, "The Meaning and Significance of Research on Genetics and Criminal Behavior", and also persuaded some critics of the original 1992 conference to attend the new one. After the change in scope, the conference ended up focusing "...far more on the significance of the research into the biology of violent behavior than it did on the research itself", as Natalie Angier noted. Despite the changed scope, however, Goodwin criticized the 1995 conference for being designed to attract controversy, rather than to address the topic from a scientific perspective.
Conference
The conference took place from Friday, September 22 to Sunday, September 24, 1995, at the Aspen Institute, a liberal think tank in Queenstown, Maryland. In total, about 70 "biologists, criminologists, historians, and philosophers" attended the conference, according to Science. Panelists included Diana Fishbein, Dorothy Nelkin, Evan Balaban, David Comings, Irving Gottesman, Adrian Raine, and Adrienne Asch.
On September 23, 1995, the second day of the conference, over 30 protesters with signs and red flags marched into the meeting. The protesters, who were affiliated with the Progressive Labor Party, accused the conference's organizers of "pushing genocide". They went on to invade one of the conference rooms at the institute, where they grabbed a microphone and denounced the meeting. The protest was ended peacefully two hours later. Some of the protesters also compared the topics discussed at the conference to eugenics, a sentiment echoed by panelist Paul Billings. In the opening discussion, Billings asked, "How do we know the bad old days are over? I would argue that the evidence is that the bad old days aren't over."
On September 24, the third and last day of the conference, Howard University professor Rodney Green began addressing the audience just as they were leaving for a coffee break. Green told them, "We have to consider whether this conference should continue. What we heard this morning...was a racist presentation under the guise of genetics."
After the conference ended, a report based on the talks given there was published in Politics and the Life Sciences. Some of the conference talks were also published in the 2001 book Genes and Criminal Behavior, published as part of Cambridge University Press's Cambridge Studies in Philosophy and Public Policy series.
References
Further reading
Conferences in the United States
1995 conferences
1995 in Maryland
Biology conferences
University of Maryland, College Park
Scientific controversies
Race-related controversies in the United States
Scientific racism
History of racism in Maryland
Genetics studies | 1995 University of Maryland conference on crime and genetics | [
"Biology"
] | 1,205 | [
"Biology theories",
"Obsolete biology theories",
"Scientific racism"
] |
59,667,652 | https://en.wikipedia.org/wiki/Samantha%20Payne | Samantha Joanne Payne MBE is an English entrepreneur. The co-founder of Open Bionics, a bionics company developing affordable prosthetics for children, Payne has won a number of international awards for her work. These include the MIT Technology Review 'Innovators under 35' in 2018, James Dyson gong for innovative engineering and Wired Innovation Fellow in 2016. In the Queen's Birthday Honours list 2020, Payne was awarded an MBE, for her work making bionic technology more accessible.
Early life and education
Born and raised in Knowle West, outside of Bristol, England. Payne is a graduate of Whitworth University and has a Bachelor of Arts/Science.
Career
She worked as a journalist, specialising in technology before becoming a co-founder of Open Bionics. In 2013, whilst working as a journalist, Payne interviewed Joel Gibbard, who was a robotics graduate at the time. Gibbard and Payne later became business partners and co-founders of Open Bionics.
Payne and Gibbard founded Open Bionics in 2014. The start-up was initially based at the Technology Business Incubator at Bristol Robotics Laboratory. The aim of the company was to develop "affordable, assistive devices that enhance the human body."
Open Bionics has partnered with Disney to make prosthetics based on Disney characters for children.
Her work at Open Bionics has been featured in The Guardian and Daily Mirror.
Innovation
Open Bionics uses 3D scanning to take the initial prosthetic fitting and 3D printing to improve the prosthetic design. These innovations significantly reduce the build-time and the material costs for a personalised hand, making prosthetics more affordable for amputees. Payne estimates that, if bought from private providers, bionic hands with multi-grip functionality cost up to £60,000, compared to £5,000 from Open Bionics.
Awards and recognition
In 2015, Payne was shortlisted for Women in Business 'Young Entrepreneur of The Year' award. In 2018, Payne featured on the Forbes 30 Under 30 list in the Sciences and Healthcare category.
References
21st-century English women engineers
21st-century English engineers
Members of the Order of the British Empire
Year of birth missing (living people)
Living people
English women in business
Bionics
Prosthetics
Whitworth University alumni
Women bioengineers
People from Bristol | Samantha Payne | [
"Engineering",
"Biology"
] | 485 | [
"Bionics"
] |
59,672,219 | https://en.wikipedia.org/wiki/Asbolane | Asbolane, previously cobalt ochre is a manganese (IV) oxy-hydroxide mineral containing also cobalt, nickel, magnesium, and calcium ions. It crystallizes in the hexagonal crystal system. Its chemical formula is .
Naming
It is named after the Greek word for "soil like soot".
References
Manganese minerals
Cobalt minerals
Hydroxide minerals
n | Asbolane | [
"Chemistry"
] | 78 | [
"Hydrate minerals",
"Hydrates"
] |
59,675,381 | https://en.wikipedia.org/wiki/Ethel%20Browning%20%28toxicologist%29 | Ethel Browning née Chadwick (1891–1969) was a medical researcher who specialised in dietetics and toxicology. She wrote many papers and 12 books, including Toxicity of Industrial Organic Solvents which became the standard reference on the subject. She was appointed as an official inspector of factories from 1940 to 1958 and continued as a consultant into her seventies.
She was born in Bury on 16 March 1891, went to school in Hough Green and then studied medicine at the University of Liverpool where she was a Roger Lyon Jones scholar, won the Holt and Kanthack medals and the university prize for medicine.
References
1891 births
1969 deaths
Alumni of the University of Liverpool
Dietitians
Factory inspectors
British toxicologists | Ethel Browning (toxicologist) | [
"Environmental_science"
] | 141 | [
"Toxicology",
"Toxicology stubs"
] |
59,675,893 | https://en.wikipedia.org/wiki/Tissue%20engineering%20of%20heart%20valves | Tissue engineered heart valves (TEHV) offer a new and advancing proposed treatment of creating a living heart valve for people who are in need of either a full or partial heart valve replacement. Currently, there are over a quarter of a million prosthetic heart valves implanted annually, and the number of patients requiring replacement surgeries is only suspected to rise and even triple over the next fifty years. While current treatments offered such as mechanical valves or biological valves are not deleterious to one's health, they both have their own limitations in that mechanical valves necessitate the lifelong use of anticoagulants while biological valves are susceptible to structural degradation and reoperation. Thus, in situ (in its original position or place) tissue engineering of heart valves serves as a novel approach that explores the use creating a living heart valve composed of the host's own cells that is capable of growing, adapting, and interacting within the human body's biological system.
Research has not yet reached the stage of clinical trials.
Procedure
Scaffolds
Various biomaterials, whether they are biological, synthetic, or a combination of both, can be used to create scaffolds, which when implanted in a human body can promote host tissue regeneration. First, cells from the patient in which the scaffold will be implanted in are harvested. These cells are expanded and seeded into the created scaffold, which is then inserted inside the human body. The human body serves as a bioreactor, which allows the formation of an extracellular matrix (ECM) along with fibrous proteins around the scaffold to provide the necessary environment for the heart and circulatory system. The initial implantation of the foreign scaffold triggers various signaling pathways guided by the foreign body response for cell recruitment from neighboring tissues. The new nanofiber network surrounding the scaffold mimics the native ECM of the host body. Once cells begin to populate the cell, the scaffold is designed to gradually degrade, leaving behind a constructed heart valve made of the host body's own cells that is fully capable of cell repopulation and withstanding environmental changes within the body. The scaffold designed for tissue engineering is one of the most crucial components because it guides tissue construction, viability, and functionality long after implantation and degradation.
Biological
Biological scaffolds can be created from human donor tissue or from animals; however, animal tissue is often more popular since it is more widely accessible and more plentiful. Xenograft, from a donor of a different species from the recipient, heart valves can be from either pigs, cows, or sheep. If either human or animal tissue is used, the first step in creating useful scaffolds is decellularization, which means to remove the cellular contents all the while preserving the ECM matrix, which is advantageous compared to manufacturing synthetic scaffolds from scratch. Many decellularization methods have been used such as the use of nonionic and ionic detergents that disrupt cellular material interactions or the use of enzymes to cleave peptide bonds, RNA, and DNA.
Fabricated
There are also current approaches that are manufacturing scaffolds and coupling them with biological cues. Fabricated scaffolds can also be manufactured using either biological, synthetic, or a combination of both materials from scratch to mimic the native heart valve observed using imaging techniques. Since the scaffold is created from raw materials, there is much more flexibility in controlling the scaffold's properties and can be more tailored. Some types of fabricated scaffolds include solid 3-D porous scaffolds that have a large pore network that permits the flow through of cellular debris, allowing further tissue and vascular growth. 3-D porous scaffolds can be manufactured through 3-D printing or various polymers, ranging from polyglycolic acid (PGA) and polylactic acid (PLA) to more natural polymers such as collagen.
Fibrous scaffolds have the potential to closely match the structure of ECM through its use of fibers, which have a high growth factor. Techniques to produce fibrous scaffolds include electrospinning, in which a liquid solution of polymers is stretched from an applied high electric voltage to produce thin fibers. Conversely to the 3-D porous scaffolds, fibrous scaffolds have a very small pore size that prevents the pervasion of cells within the scaffold.
Hydrogel scaffolds are created by cross-linking hydrophilic polymers through various reaction such as free radical polymerization or conjugate addition reaction. Hydrogels are beneficial because they have a high water content, which allows the ease of nutrients and small materials to pass through.
Biocompatibility
The biocompatibility of surgically implanted foreign biomaterial refers to the interactions between the biomaterial and the host body tissue. Cell line as well as cell type such as fibroblasts can largely impact tissue responses towards implanted foreign devices by changing cell morphology. Thus the cell source as well as protein adsorption, which is dependent on biomaterial surface property, play a crucial role in tissue response and cell infiltration at the scaffold site.
Methodology
Inflammatory response
Acute inflammation
Implantation of any foreign device or material through the means of surgery results in at least some degree of tissue trauma. Therefore, especially when removing a native heart valve either partially or completely, the tissue trauma will trigger a cascade of inflammatory responses and elicit acute inflammation. During the initial phase of acute inflammation, vasodilation occurs to increase blood flow to the wound site along with the release of growth factors, cytokines, and other immune cells. Furthermore, cells release reactive oxygen species and cytokines, which cause secondary damage to surrounding tissue. These chemical factors then proceed to promote the recruitment of other immune responsive cells such as monocytes or white blood cells, which help foster the formation of a blood clot and protein-rich matrix.
Chronic inflammation
If the acute inflammatory response persists, the body then proceeds to undergo chronic inflammation. During this continual and systemic inflammation phase, one of the primary driving forces is the infiltration of macrophages. The macrophages and lymphocytes induce the formation of new tissues and blood vessels to help supply nutrients to the biomaterial site. New fibrous tissue then encapsulates the foreign biomaterial in order to minimize interactions between the biomaterial and surrounding tissue. While the prolonging of chronic inflammation may be a likely indicator for an infection, inflammation may on occasion be present upwards to five years post-surgery. Chronic inflammation marked by the presence of fibrosis and inflammatory cells was observed in rat cells 30 days post implantation of a device.
Following chronic inflammation, mineralization occurs approximately 60 days after implantation due to the buildup of cellular debris and calcification, which has the potential to compromise the functionality of biocompatible implanted devices in vivo.
Foreign body response
Under normal physiological conditions, inflammatory cells protect the body from foreign objects, and the body undergoes a foreign body reaction based on the adsorption of blood and proteins on the biomaterial surface. In the first two to four weeks post implant, there is an association between biomaterial adherent macrophages and cytokine expression near the foreign implant site, which can be explored using semi-quantitative RT-PCR. Macrophages fuse together to form foreign body giant cells (FBGCs), which similarly express cytokine receptors on their cell membranes and actively participate in the inflammatory response. Device failure in organic polyether polyurethane (PEU) pacemakers compared to silicone rubber showcases that the foreign body response may indeed lead to degradation of biomaterials, causing subsequent device failures. The utilization of to prevent functionality and durability compromise is proposed to minimize and slow the rate of biomaterial degradation.
Benefits
Tissue engineered heart valves offer certain advantages over traditional biological and mechanical valves:
Living valve – The option of a living heart valve replacement is highly optimal for children as the live valve has the ability to grow and respond to its biological environment, which is especially beneficial for children whose bodies are continually changing. This option would help reduce the number of reoperation needed in a child's life.
Customized process – Since the scaffolds used in tissue engineering can be manufactured from scratch, there is a higher degree of flexibility and control. This allows the potential of tailoring tissue engineered heart valves and its properties such as the scaffold's shape and biomaterial makeup to be tailored specifically to the patient.
Risks and challenges
Many risks and challenges must still be addressed and explored before tissue engineered heart valves can fully be clinically implemented:
Contamination – Particular source materials can foster a microbiological environment that is conducive to the susceptibility of viruses and infectious diseases. Anytime an external scaffold is implanted within the human body, contamination, while inevitable, can be diminished through the enforcement of sterile technique.
Scaffold Interactions - There are many risks associated with the interactions between cells and the implanted scaffold as specific biocompatibility requirements are still largely unknown with current research. The response to these interactions are also highly individualistic, dependent on the specific patient's biological environment; therefore, animal models researched prior may not accurately portray outcomes in the human body. Due to the highly interactive nature between the scaffold and surrounding tissue, properties such as biodegradability, biocompatibility, and immunogenicity must all be carefully considered as they are key factors in the performance of the final product.
Structural complexity – Heart valves with their heterogeneous structure are very complex and dynamic, thus posing a challenge for tissue engineered valves to mimic. The new valves must have high durability while also meeting the anatomical shape and mechanical functions of the native valve.
History
Synthetic scaffolds
Studies performed seeded scaffolds made of polymers with various cell lines in vitro, in which the scaffolds degraded over time while leaving behind a cellular matrix and proteins. The first study on tissue engineering of heart valves was published in 1995. During 1995 and 1996, Shinoka used a scaffold made of polyglycolic acid (PGA), approved by the FDA for human implantation, and seeded it with sheep endothelial cells and fibroblasts with the goal of replacing a sheep's pulmonary valve leaflet. What resulted from Shinoka's study was an engineered heart valve that was much thicker and more rigid, which prompted Hoerstrup to conduct a study to replace all three pulmonary valve leaflets in a sheep using a poly-4-hydroxybutyrate (P4HB) coated PGA scaffold and sheep endothelial cells and myofibroblast.
Biological scaffolds
Another option studied was using decellularized biological scaffolds and seeding them with their corresponding cells in vitro. In 2000, Steinhoff implanted a decellularized sheep pulmonary valve scaffold seeded with sheep endothelial cells and myofibroblasts. Dohmen then created a decellularized cryopreserved pulmonary allograft scaffold and seeded it with human vascular endothelial cells to reconstruct the right ventricular outflow tract (RVOT) in a human patient in 2002. Perry in 2003 seeded a P4HB coated PGA scaffold with sheep mesenchymal stem cells in vitro; however, an in vivo study was not performed. In 2004, Iwai conducted a study using a poly(lactic-co-glycolic acid) PLGA compounded with collagen microsponge sphere scaffold, which was seeded with endothelial and smooth muscle cells at the site of a dog's pulmonary artery. Sutherland in 2005 utilized a sheep mesenchymal stem cell seeded PGA and poly-L-lactic acid (PLLA) scaffold to replace all three pulmonary valve leaflets in a sheep.
In vivo implant studies
A handful of studies utilized tissue engineering of heart valves in vivo in animal models and humans. In 2000, Matheny conducted a study in which he used a pig's small intestinal submucosa to replace one pulmonary valve leaflet. Limited studies have also been conducted in a clinical setting. For instance in 2001, Elkins implanted SynerGraft treated decellularized human pulmonary valves in patients. Simon similarly used SynerGraft decellularized pig valves for implantation in children; however, these valves widely failed as there were no host cells but rather high amounts of inflammatory cells found at the scaffold site instead. Studies led by Dohmen, Konertz, and colleagues in Berlin, Germany involved the implantation of a biological pig valve in 50 patients who underwent the Ross operation from 2002 to 2004. Using a decellularized porcine xenograft valve, also called Matrix P, in adults with a median age of 46 years, the aim of the study was to offer a proposal for pulmonary valve replacement. While some patients died postoperatively and had to undergo reoperation, the short-term results appear to be going well as the valve is behaving similarly to a native, healthy valve. One animal trial combined the transcatheter aortic valve replacement (TAVR) procedure with tissue engineered heart valves (TEHVs). A TAVR stent integrated with human cell-derived extracellular matrix was implanted and examined in sheep, in which the valve upheld structural integrity and cell infiltration, allowing the potential clinical application to extend TAVR to younger patients.
Research
While many in vitro and in vivo studies have been tested in animal models, the translation from animal models to humans has not begun. Factors such as the size of surgical cut sites, duration of the procedure, and available resources and cost must all be considered. Synthetic nanomaterials have the potential to advance scaffoldings used in tissue engineering of heart valves. The use of nanotechnology could help expand beneficial properties of fabricated scaffolds such as higher tensile strength.
See also
Tissue engineering
Valvular heart disease
Valve replacement
Artificial heart valve
Nanotechnology
References
Tissue engineering
Organ transplantation | Tissue engineering of heart valves | [
"Chemistry",
"Engineering",
"Biology"
] | 2,955 | [
"Biological engineering",
"Cloning",
"Chemical engineering",
"Tissue engineering",
"Medical technology"
] |
59,675,902 | https://en.wikipedia.org/wiki/Extremophiles%20in%20biotechnology | Extremophiles in biotechnology is the application of organisms that thrive in extreme environments to biotechnology.
Extremophiles are organisms that thrive in the most volatile environments on the planet and due to their talents, they have begun playing a large role in biotechnology. These organisms live everywhere from environments of high acidity or salinity to areas with limited or no oxygen. Scientists show keen interest in organisms with rare or strange talents and in the past 20-30 years extremophiles have been at the forefront with thousands of researchers delving into their abilities. The area in which there has been the most talk, research, and development in relation to these organisms is biotechnology.
Scientists around the globe are either extracting DNA to modify genomes or directly using extremophiles to complete tasks. Thanks to the discovery and interest in these organisms the enzymes used in polymerase chain reaction (PCR) were found, making the rapid replication of DNA in the lab possible. Since they gained the spotlight researchers have been amassing databases of genome data for the hopes that new traits and abilities can be used to further biotechnical advancements. Everything from the biodegradation of waste to the production of new fuels is on the horizon with the developments made in the field of biotechnology. There are many different kinds of extremophiles with each kind favoring a different environment. These organisms have become more and more important to biotechnology as their genomes have been uncovered, revealing a plethora of genetic potential. Currently the main uses of extremophiles lies in processes such as PCR, biofuel generation and biomining, but there are many other smaller scale operations at play. There are also labs that have identified what they wish to do with extremophiles, but haven't been able to fully achieve their goals. While these large scale goals have not yet been met the scientific community is working towards their completion in hope of creating new technologies and processes.
Overview of extremophiles
Extremophile is the term that covers a large group of organisms, most prominently Archaeans, which have evolved to fill the niches of extremely inhospitable environments. Such environments include high or low temperatures, high levels of salinity, high or low pH levels, and areas where volatile chemicals are prominent. These organisms have made some of the most undesirable locations on the planet their home. A few examples of these locations include thermal vents at the bottom of the ocean, soda lakes, runoffs from chemical factories and the trash heaps of landfills.
There are 4 major types of extremophiles:
Thermophiles
Thermophilic extremophiles live in areas of extreme heat with the best example being geothermal vents at the bottom of the ocean. The benefit of these organisms lies in the polymers and enzymes produced within them as they are highly thermostable.
Halophilies
Halophilic extremophiles live in areas of high salinity such as solar salterns and soda lakes. Their ability to consume and thrive in areas of such salinity open up possible benefits such as inoculating crops in salt rich soils to help them grow. Another use found for them lies in their production of polymers used to make biodegradable plastics.
Methanogens
Methanogenic extremophiles live just about anywhere and are the most widespread. These organisms take various simple organic compounds and use them to synthesize methane as their source of energy. There are no other known organisms that use the synthesis of methane as a form of energy production.
Psychrophiles
Psychrophilic extremophiles have the ability to maintain high growth rates and enzyme activity at temperatures even as low as 0°C. This presents the possibility of utilizing enzymes found in these organisms in parallel to how thermophilic organism enzymes are used, but at low temperatures as opposed to high temperatures.
Having the ability to live in such harsh environment comes from the organisms traits and abilities that are coded into their genomes. Changes inherited over time via DNA have allowed these organisms to build up various resistances and immunities to the volatile nature of their homes. It is these traits that have scientists so fixated on extremophiles because the genes that allow for said abilities can be taken from extremophiles and used in various biotechnical processes. A good example of this would be how Taq Polymerase was isolated from the bacteria Thermus aquaticus and was then used to make the process of PCR possible. In some cases even the entire organism can be utilized due to how it functions in nature. A good example of this would be the use of methanogenic extremophiles to assist in the decomposition of waste. While only four major types of extremophiles are listed above, there are many more types that are not mentioned in this article.
Importance
A great deal of biological and chemical processes undertaken in laboratories take great stretches of time, are extremely delicate and tend to be costly. This is due to the fact that general biological enzymes, proteins and other various organic compounds have very specific requirements for them to function properly. These are generally moderate conditions and therefore are known as mesophilic. Catalysts that involve changes in temperature, salinity, or acidity can impact the mesophilic organic compounds and products within a given process which in turn negatively affects the outcome. To deal with this, scientists in the past had to use longer experimental pathways to meet the moderate conditions. This, as stated previously, extends the time it takes to perform experiments and processes as well as increases costs.
To overcome this issue scientists have turned to extremophiles due to their natural abilities to handle extreme conditions. These abilities are linked to genes which can be isolated, extracted and replicated in the lab. With this, the genetic information can then be implanted in the given enzymes, polymers, proteases and other various organic compounds to give them desired resistance. This allows for biological and chemical processes to be completed rapidly as the careful, long winded strategies can be bypassed. Extremophiles, both themselves and their DNA, are helping scientists to optimize lengthy research techniques and processes.
Applications
PCR
The polymerase chain reaction (PCR) was developed in the 1980s by Kary Mullis. Mullis would later receive the Nobel Prize for his creation of this process in 1993. PCR uses one of the heat resistant enzymes found in the thermophile T. aquaticus to rapidly and efficiently make copies of specific strands of DNA. The small sample of the target DNA is added to a test tube along with DNA primers, DNA nucleotides, Taq polymerase, and a buffer solution. Once these five key parts are combined they can be put into a PCR thermocycler. In this device the mixture is exposed to a series of temperatures over and over again cycling between 94-95°C, 50-56°C, and 72°C. These three stages are known as the denaturing, annealing and extending stages. During the denaturing stage at 94-95°C the DNA chains separate allowing for new bonds to be made. Then during the annealing stage from 50-56°C primers attach to the single strands of DNA to prepare them for replication. Finally, the extending stage at 72°C the strands of DNA replicate as they would naturally as the DNA nucleotides are added reforming the double stranded helix. These stages are cycled through multiple times until the desired amount of DNA is obtained. Without the enzyme produced by T. aquaticus, Taq polymerase, this process would not be possible as the components would normally denature at such high temperatures.
Biofuel production
Fuels play a large part in everyday life in everything from driving a car and heating homes to large scale industrial processes and heavy machinery. As natural gases and fuels are being used up scientists have focused their gaze on possible replacements for said fuels. One way in which this is being done is through the utilization of various methanogenic and thermophilic strains of bacteria. These extremophiles in large quantities are able to take in various substances such as sugars, cellulose, and various waste products to produce methane, butanol and biodiesel. While butanol in high percentages would normally inhibit the growth and function of biological organisms, some bacterial strains, primarily thermophiles, have been engineered to handle butanol even in high concentrations. One of the more recent developments in this area is the discovery of extremophile strains of algae which can be used to produce biodiesel. Cyanidium caldarium is noted as one of the most promising strains due to the high lipid content of the biodiesel products it creates. While this application has not yet widely developed to large scale utilization, scientists working in this field hope to find an efficient and sustainable solution involving extremophiles soon.
Biomining
Through work with various extremophiles the technique of biomining was developed. Also known as bioleaching, the process involves the use of acidophiles in the removal of insoluble sulfides and oxides from various metals as they are mined from the earth. The normal process of heap leaching involves mixing mined metals with highly volatile chemicals such as cyanide. The process of bioleaching is noted as a safer approach to the mining process. Along with this it is also much better for the environment. With heap leaching comes the possibility of runoff and spills that would poison the environment as it seeps into the ground. With biomining this worry is reduced as the conditions can be easily maintained using thermophilic and acidophilic strains of bacteria. Not only has this process been noted as safer and more environmentally friendly, but is also able to extract more metal. Heap leaching has about a 60% extraction rate while bioleaching has seen rates up to 90%. So far gold, silver, copper, zinc, nickel, and uranium have been mined successfully using this process.
These three examples listed above are a few of the primary applications of extremophiles in biotechnology, but they are not the only ones. Other various applications that will not be fully described here include: carotenoid production, protease/lipase production, Glycosyl hydrolase production and sugar production. These secondary applications focus on the production of biological compounds that can be used within primary applications such as those listed above.
Future developments
Thanks to the increased interest in extremophiles the revolutionary technique of PCR was pioneered and brought the field of DNA study to the next level. Following this trend scientists in both biotech and industry want to push farther and find new ways to impact the scientific community. One way that is currently being studied is the production of plastics by halophilic extremophiles so that modern day oil-based plastics can become a thing of the past. This would bring biodegradable plastics to the world market, which in the long run is proposed as a way to help fight the world's garbage problem. Another advancement that scientists hope to make using these organisms is to increase the degradation of landfills around the world using methanogenic species that thrive on the organic compounds found there. Not only would this reduce waste, but the methane produced is hoped to be collected and used as an energy source. One other interesting future development lies in the field of medicine. Some biotechnical labs are looking into using extremophiles engineered to produce portions of viruses on their surface to elicit immune system responses. This would help train immune memory and antibody response to defend the body in case said virus ever attacks. While this is just a handful of examples there are many more advancements and developments being worked on using extremophiles in hopes of creating a better future.
References
Further reading
Extremophiles
Biotechnology | Extremophiles in biotechnology | [
"Biology",
"Environmental_science"
] | 2,474 | [
"Biotechnology",
"Organisms by adaptation",
"Extremophiles",
"Bacteria",
"nan",
"Environmental microbiology"
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59,675,946 | https://en.wikipedia.org/wiki/Trilateration | Trilateration is the use of distances (or "ranges") for determining the unknown position coordinates of a point of interest, often around Earth (geopositioning).
When more than three distances are involved, it may be called multilateration, for emphasis.
The distances or ranges might be ordinary Euclidean distances (slant ranges) or spherical distances (scaled central angles), as in true-range multilateration; or biased distances (pseudo-ranges), as in pseudo-range multilateration.
Trilateration or multilateration should not be confused with triangulation, which uses angles for positioning; and direction finding, which determines the line of sight direction to a target without determining the radial distance.
Terminology
Multiple, sometimes overlapping and conflicting terms are employed for similar concepts – e.g., multilateration without modification has been used for aviation systems employing both true-ranges and pseudo-ranges. Moreover, different fields of endeavor may employ different terms. In geometry, trilateration is defined as the process of determining absolute or relative locations of points by measurement of distances, using the geometry of circles, spheres or triangles. In surveying, trilateration is a specific technique.
True-range multilateration
Pseudo-range multilateration
References
Geometry
Geopositioning | Trilateration | [
"Mathematics"
] | 260 | [
"Geometry"
] |
59,676,244 | https://en.wikipedia.org/wiki/QM-AM-GM-HM%20inequalities | In mathematics, the QM-AM-GM-HM inequalities, also known as the mean inequality chain, state the relationship between the harmonic mean, geometric mean, arithmetic mean, and quadratic mean (also known as root mean square). Suppose that are positive real numbers. Then
These inequalities often appear in mathematical competitions and have applications in many fields of science.
Proof
There are three inequalities between means to prove. There are various methods to prove the inequalities, including mathematical induction, the Cauchy–Schwarz inequality, Lagrange multipliers, and Jensen's inequality. For several proofs that GM ≤ AM, see Inequality of arithmetic and geometric means.
AM-QM inequality
From the Cauchy–Schwarz inequality on real numbers, setting one vector to :
hence . For positive the square root of this gives the inequality.
HM-GM inequality
The reciprocal of the harmonic mean is the arithmetic mean of the reciprocals , and it exceeds by the AM-GM inequality. implies the inequality:
The n = 2 case
When n = 2, the inequalities become
for all
which can be visualized in a semi-circle whose diameter is [AB] and center D.
Suppose AC = x1 and BC = x2. Construct perpendiculars to [AB] at D and C respectively. Join [CE] and [DF] and further construct a perpendicular [CG] to [DF] at G. Then the length of GF can be calculated to be the harmonic mean, CF to be the geometric mean, DE to be the arithmetic mean, and CE to be the quadratic mean. The inequalities then follow easily by the Pythagorean theorem.
Tests
To infer the correct order, the four expressions can be evaluated with two positive numbers.
For and in particular, this results in .
See also
Inequalities among pythagorean means
Generalized mean inequality
References
External links
The HM-GM-AM-QM Inequalities
Useful inequalities cheat sheet entry "means" on the right of page 1
Inequalities | QM-AM-GM-HM inequalities | [
"Physics",
"Mathematics"
] | 440 | [
"Means",
"Mathematical analysis",
"Point (geometry)",
"Mathematical theorems",
"Geometric centers",
"Binary relations",
"Mathematical relations",
"Inequalities (mathematics)",
"Articles containing proofs",
"Mathematical problems",
"Symmetry"
] |
59,676,344 | https://en.wikipedia.org/wiki/Saad%20Omer | Saad B. Omer is an American vaccinologist and infectious disease epidemiologist. He is the Founding Dean of the Peter O’Donnell Jr. School of Public Health at UT Southwestern Medical Center in Dallas. He is also a Professor in the O’Donnell School of Public Health and holds the Lyda Hill Deanship of the School of Public Health at UT Southwestern.
He was previously the inaugural Director of the Yale Institute for Global Health. He was also a Professor of Medicine (Infectious Diseases) at Yale School of Medicine and the Susan Dwight Bliss Professor of Epidemiology of Microbial Diseases at Yale School of Public Health.
In 2009, he received the Maurice R. Hilleman Early-Stage Career Investigator Award from the National Foundation for Infectious Diseases. His research on vaccination rates, exemptions, and outbreaks of vaccine-preventable diseases has been widely covered in the media. On March 5, 2019, he testified at a US Senate hearing on vaccines, stating that preventing the next potential resurgence of measles will require a broad-based federal response to improve vaccine access.
He has published widely in biomedical journals including the New England Journal of Medicine, JAMA, Lancet, Pediatrics, American Journal of Public Health, and Science. Moreover, he has written op-eds for publications such as the New York Times, Politico, and the Washington Post.
References
External links
Faculty page
Omer Research Group website
Living people
American epidemiologists
Vaccinologists
Emory University School of Medicine faculty
Emory University faculty
American public health doctors
Year of birth missing (living people)
Members of the National Academy of Medicine | Saad Omer | [
"Biology"
] | 334 | [
"Vaccination",
"Vaccinologists"
] |
59,676,605 | https://en.wikipedia.org/wiki/Institute%20of%20Theoretical%20Astrophysics | The Institute of Theoretical Astrophysics (Norwegian: Institutt for teoretisk astrofysikk, abbreviated ITA) is a research and teaching institute dedicated to astronomy, astrophysics and solar physics located at Blindern in Oslo, Norway. It is a department of The Faculty of Mathematics and Natural Sciences at the University of Oslo. It was founded in its current form by Svein Rosseland with funding from the Rockefeller Foundation in 1934, and was the first of its kind in the world when it opened. Prior to that, it existed as the University Observatory which was created in 1833. It thus is one of the university's oldest institutions. As of 2019, it houses research groups in cosmology, extragalactic astronomy, and The Rosseland Centre for Solar Physics, a Norwegian Centre of Excellence.
History
The observatory
Prior to 1934, the university's astronomy efforts revolved around the University Observatory (Norwegian: Universitetsobservatoriet, abbreviated Observatoriet, lit. the Observatory) located downtown Oslo. The first observation facilities were provided in 1815 to the newly appointed professor Christopher Hansteen of the recently established Royal Frederick University (which was renamed the University of Oslo in 1939) in an octagonal shack at Akershus Festning, Christiania. Construction began in 1831 on a larger observatory which also could house Hansteen and his family. At its completion in 1833 it became the first building to have been erected by the university.
An Institute of Theoretical Astrophysics
The Observatory's final director, professor Svein Rosseland (appointed in 1928) did not consider its future to be promising. In a letter to a colleague, he wrote,
He visited the Harvard College Observatory in 1929, and accepted a professorship there. However, rector Sem Sæland of the University of Oslo saw this as a great loss, as Rosseland already had become an internationally renowned scientist at the time. Sæland coordinated a political effort in which Rosseland was offered to manage an astronomical fund provided by the state, prospects of new university facilities, and was promised a general renovation of the observatory. Rosseland accepted, and returned to Oslo in 1930. He then contacted Niels Bohr in Copenhagen who recently had founded the Institute of Theoretical Physics for inspiration and his level plans. Rosseland concluded that the director should reside at the institute. In his opinion, work did not comply with working hours, and the director should always be available. An architectural competition was announced, and the winning design was sent to the Rockefeller Foundation. His proposal of an institute of theoretical astrophysics did not exist elsewhere in the world at the time. The foundation replied 15 April 1931, granting him 105,000 dollars to erect the institute and 15,000 dollars to obtain scientific equipment.
The architectural firm of Finn Bryn and Johan Fredrik Ellefsen designed the building for Rosseland at Blindern campus in Oslo. It opened 1 July 1934 and was named Svein Rosselands hus (lit. the house of Svein Rosseland). The building is a striking example of functionalism, unlike the nearby building for physics and chemistry which originally was designed in neoclassical style. Both scientists and the library were moved from the observatory to the new premises. The two first floors and the basement were purposed for research and teaching, and Rosseland himself resided in the upper three floors. A plaque honoring the Rockefeller Foundation can be found near the entrance.
In the early days, the institute housed Rosseland himself, his assistant Gunnar Randers, two of the founders of modern meteorology: retired Norwegian dean of science Vilhelm Bjerknes and professor Halvor Solberg, as well as Carl Størmer, a mathematics professor who also studied the northern lights. Rosseland's international recognition led to visits from prominent scientists such as Martin Schwarzschild.
Instruments, observatories, and telescopes
The institute housed the Oslo Analyzer in its basement between 1934 and 1954. It was the most powerful differential analyzer in the world for four years after its creation. Key pieces were buried in the garden behind the institute during WW2 to prevent the machine from being used by the nazis.
The institute had its own solar observatory outside Oslo between 1954 and 1987, the Harestua Solar Observatory. It has been used for science educational purposes after ceasing to exist as a research facility. A subsequent telescope was proposed, the Large European Solar Telescope. After a completion of an initial scientific requirement analysis in 1982, a legal body was formed in 1983. The telescope was however never realized. Solar physicists at ITA have routinely been using the Swedish Solar Telescope since it saw first light in 2002.
The institute contributed to, and made use of, the solar imager High Resolution Telescope and Spectrograph of the Naval Research Laboratory which was launched on rockets and flew once with the Space Shuttle between 1975 and 1985.
The space-borne Solar and Heliospheric Observatory was launched in 1995. The institute provided the ground test system and computers.
In 1988, the Nordic Optical Telescope at La Palma was opened. It was co-funded by Norway and is used by astronomers at ITA.
The works of the former celestial mechanics research group at the institute were instrumental in determining the path ESA's Rosetta spacecraft would take when approaching its target, the comet 67P/Churyumov–Gerasimenko in 2014.
The institute lead the Norwegian contributions to the Planck mission of ESA until its final release of results in 2018. Scientists at the institute were instrumental in analyzing the resulting maps of the cosmic microwave background (CMB).
A Center of Excellence
The solar physics group at the institute was granted status as a Norwegian Centre of Excellence in 2017 for the period 2017–2027 under the direction of Mats Carlsson.
Directors
Christopher Hansteen (1834–1861)
Carl Frederik Fearnley (1861–1890)
Hans Geelmuyden (1890–1919)
Jens Fredrik Schroeter (1919–1927)
Svein Rosseland (1928–35 at the observatory, 1935–1965 at ITA)
Mats Carlsson (1997–2003 (?))
Per Barth Lilje (2003–2012)
Viggo Hansteen (2013–2017)
Per Barth Lilje (2017–)
Research
The institute is engaged in various fields of theoretical, observational and numerical astrophysics.
The cosmology group is engaged in analysis of data from cosmic microwave background-related experiments such as CORE, GreenPol, LiteBIRD, PASIPHAE, QUIET and SPIDER. The group is also researching the nature of the cosmological accelerating expansion and the nature of dark matter, both through theoretical and numerical investigations into modifying general relativity as well as the future Euclid mission of ESA.
The extragalactic astronomy group is organized under the cosmology group. Its scientists use both simulations of galaxy formations, radiative transfer simulations, and observations of gravitationally lensed galaxies to understand and investigate the Universe beyond our own galaxy. Observations are carried out with the Hubble Space Telescope and the Nordic Optical Telescope among others. The group is also a key player in the COMAP carbon monoxide intensity mapping experiment.
The Rosseland Centre for Solar Physics combines theory, numerics and observations to provide insights into the solar atmosphere. It is regarded as one of the world's foremost solar physics research institutions. With an allocated amount of 115 million CPU hours in 2018, it also is the most data intensive research group in Norway. The institute hosts the European data center for data from the Hinode satellite. It has an in-house developed 3D numerical model of the solar atmosphere called Bifrost. Besides using the Swedish Solar Telescope and Hinode for solar observations, the group also makes use of the space-borne Interface Region Imaging Spectrograph (IRIS), the Solar Dynamics Observatory as well as the ground-based Swedish Solar Telescope (SST) and the Atacama Large Millimeter Array (ALMA).
The Almanac of Norway
The official almanac of Norway has been published since 1644. After the dissolution of the Denmark-Norway union in 1814, the almanac has been edited in Norway. In 1814, it was edited by the Danish astronomer Thomas Bugge. Christopher Hansteen became editor in 1815 and remained so until 1862. Directors and astronomers at the Observatory and ITA have been editing it ever since.
References
Astrophysics research institutes
University of Oslo | Institute of Theoretical Astrophysics | [
"Physics"
] | 1,709 | [
"Astrophysics research institutes",
"Astrophysics"
] |
59,677,212 | https://en.wikipedia.org/wiki/Lone%20divider | The lone divider procedure is a procedure for proportional cake-cutting. It involves a heterogenous and divisible resource, such as a birthday cake, and n partners with different preferences over different parts of the cake. It allows the n people to divide the cake among them such that each person receives a piece with a value of at least 1/n of the total value according to his own subjective valuation.
The procedure was developed by Hugo Steinhaus for n = 3 people. It was later extended by Harold W. Kuhn to n > 3, using the Frobenius–Konig theorem. A description of the cases n = 3, n = 4 appears in and the general case is described in.
Description
For convenience we normalize the valuations such that the value of the entire cake is n for all agents. The goal is to give each agent a piece with a value of at least 1.
Step 1. One player chosen arbitrarily, called the divider, cuts the cake into n pieces whose value in his/her eyes is exactly 1.
Step 2. Each of the other n − 1 partners evaluates the resulting n pieces and says which of these pieces he considers "acceptable", i.e., worth at least 1.
Now the game proceeds according to the replies of the players in step 3. We present first the case n = 3 and then the general case.
Steinhaus' procedure for the case n = 3
There are two cases.
Case A: At least one of the non-dividers marks two or more pieces as acceptable. Then, the third partner picks an acceptable piece (by the pigeonhole principle he must have at least one); the second partner picks an acceptable piece (he had at least two before, so at least one remains); and finally the divider picks the last piece (for the divider, all pieces are acceptable).
Case B: Both other partners mark only one piece as acceptable. Then, there is at least one piece that is acceptable only for the divider. The divider takes this piece and goes home. This piece is worth less than 1 for the remaining two partners, so the remaining two pieces are worth at least 2 for them. They divide it among them using divide and choose.
The procedure for any n
There are several ways to describe the general case; the shorter description appears in and is based on the concept of envy-free matching – a matching in which no unmatched agent is adjacent to a matched piece.
Step 3. Construct a bipartite graph G = (X + Y, E) in which each vertex in X is an agent, each vertex in Y is a piece, and there is an edge between an agent x and a piece y iff x values y at least 1.
Step 4. Find a maximum-cardinality envy-free matching in G. Note that the divider is adjacent to all n pieces, so |NG(X)| = n ≥ |X| (where NG(X) is the set of neighbors of X in Y). Hence, a non-empty envy-free matching exists.
Step 5. Give each matched piece to its matched agent. Note that each matched agent has a value of at least 1, and thus goes home happily.
Step 6. Recursively divide the remaining cake among the remaining agents. Note that each remaining agent values each piece given away at less than 1, so he values the remaining cake at more than the number of agents, so the precondition for recursion is satisfied.
Query complexity
At each iteration, the algorithm asks the lone divider at most n mark queries, and each of the other agents at most n eval queries. There are at most n iterations. Therefore, the total number of queries in the Robertson-Webb query model is O(n2) per agent, and O(n3) overall. This is much more than required for last diminisher (O(n) per agent) and for Even-Paz (O(log n) per agent).
See also
For other procedures for solving the same problem, see proportional cake-cutting.
One advantage of lone-divider is that it can be modified to yield a symmetric fair cake-cutting procedure.
Fair Division: Method of Lone Divider at Cut-the-Knot.
References
Fair division protocols
Division (mathematics)
Number theory
Cake-cutting | Lone divider | [
"Mathematics"
] | 904 | [
"Discrete mathematics",
"Number theory"
] |
59,677,453 | https://en.wikipedia.org/wiki/Tonelada | The tonelada (Spanish and Portuguese for "a tunful") was a conventional Spanish and Portuguese unit of mass, volume, and capacity roughly equivalent to the English "ton" in its various senses. In English following Spain and Portugal's adoption of the metric system, the toneladas are most often used to specify the capacity of Spanish and Portuguese ships during the Age of Exploration with greater care than simply using the misleadingly vague calque "ton". However, as with the ton, the specific size of the units varied with time and location.
Spanish unit
The Spanish tonelada of volume was reckoned as 2 butts or pipes ( or ) and equivalent to 968.2 liters or 255.8 gallons.
The Spanish tonelada of shipping capacity varied in size and method of computation over the years but scholars place the usual value for southern Spain from Columbus through the Age of Exploration at about or This was the same as the "sea ton" () used in early modern Bordeaux, France, and roughly half of the English old measure and British gross register tons. (The present system of tonnage varies logarithmically with ship size and cannot be linearly converted.) At other times, it was closer to of the British shipping ton.
The Spanish tonelada of mass was normally reckoned as 20 quintals or 2000 Spanish pounds (). The Castilian Spanish pound was standardized as about 460 grams by the 19th century, producing a tonelada of around 920 kilograms or 2030 pounds avoirdupois. In Mexico, the tonelada was instead reckoned as 2240 Castilian pounds, 1030.4 kg or 2266.9 lbs., while Valencia used only 1920 slightly heavier poundsabout 534 gramsso that it was equivalent to 1025.3 kg or 2255.7 lbs.
Portuguese unit
The Portuguese tonelada of volume was initially reckoned as 2 pipes (), which in the 19th century was equivalent to 860.3 liters or 226.3 gallons. Following metrification, Portugal's used a quasimetric tonelada of exactly 800 liters while Brazil used a kiloliter tonelada of exactly 1000 liters.
The Portuguese tonelada of mass was reckoned as 1728 arratels in Europe and Rio de Janeiro but 2240 arratels in Pernambuco. The arratel was standardized in Portugal and Brazil as about 460 grams by the 19th century, producing a lighter tonelada of around 793.2 kilograms or 1748.5 pounds avoirdupois and a heavier one around 1028.2 kg and 2266.7 lbs.
See also
Metric ton (Portuguese & or simply )
English tons (Portuguese & , , or simply )
Notes
References
Citations
Bibliography
.
.
.
.
.
.
.
Spanish customary measurements
Obsolete units of measurement
Units of mass
Units of volume
Nautical terminology
Ship measurements | Tonelada | [
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] | 599 | [
"Obsolete units of measurement",
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59,679,002 | https://en.wikipedia.org/wiki/C9H21N3 | {{DISPLAYTITLE:C9H21N3}}
The molecular formula C9H21N3 (molar mass: 171.28 g/mol, exact mass: 171.1735 u) may refer to:
2-tert-Butyl-1,1,3,3-tetramethylguanidine
1,4,7-Trimethyl-1,4,7-triazacyclononane | C9H21N3 | [
"Chemistry"
] | 96 | [
"Isomerism",
"Set index articles on molecular formulas"
] |
59,679,292 | https://en.wikipedia.org/wiki/Zimbabwe%20fuel%20protests | Protests began in Zimbabwe on 14 January 2019 following a 130% increase in the price of fuel imposed by the government of Emmerson Mnangagwa. Thousands of Zimbabweans protested against the price increase, along with increasing levels of poverty, the poor state of the economy, and declining standards of living. The government responded with a coordinated crackdown that resulted in hundreds of arrests and multiple deaths. The protests stopped after three days; by 17 January, businesses started reopening as the protests ended.
Background
In an effort to improve the financial and fiscal situation of the country following the establishment of the Mnangagwa government in 2017, the government initiated a number of austerity policies in an effort to kick-start the moribund economy. By October 2018, foreign currency shortages led to large scale business closures and shortages of imported commodities, including fuel. This led to persistent fuel shortages, strikes by government workers, and a worsening economic environment.
On 12 January 2019, the government of Emmerson Mnangagwa announced that the Zimbabwe Energy Regulatory Agency would more than double fuel prices as of midnight that night. The price of diesel rose from US$1.38 to US$3.11 per litre (equivalent to $11.77 per US gallon or €2.73 per litre) and that of petrol from $1.43 to $3.31 per litre ($12.53 per US gallon or €2.91 per litre), for an increase of almost 130% overnight, making Zimbabwe's fuel the most expensive in the world at the time. Mnangagwa stated that the price increases were needed to reduce fuel shortages and illegal trading. The Zimbabwe Congress of Trade Unions called for a three-day strike in protest at the price increases.
Protests
During the protests
Protests began in Harare on 14 January 2019. In response, the police and military launched a coordinated response that involved raiding the homes of some residents. Beyond the capital, disturbances were also reported in the cities of Mutare and Bulawayo. By the end of the day, the government reported that three people, including one policeman, had died in the protests. Non-government sources reported that around 200 people had been arrested and that eight had been killed in the protests by police by the end of the first day of protests.
The Zimbabwe Association of Doctors for Human Rights (ZADHR) stated that 172 people had been injured, of which 68 were treated for gunshot wounds. Indiscriminate acts of violence by the police on both protesters and bystanders were also reported, along with acts of looting by some protesters in Harare, Bulawayo and Kadoma. By 18 January, the ZADHR had recorded 844 human rights violations that included 78 gunshot injuries, 466 arbitrary arrests and detentions, as well as 242 cases of assault and degrading treatment.
On 15 January, internet monitoring group NetBlocks reported the blocking of over a dozen social media and messaging platforms in Zimbabwe including WhatsApp, Facebook, Twitter and Instagram followed by total internet blackouts. The first three days of the disruption cost the Zimbabwe's economy an estimated $17 million as the government extended its disruption to a full shutdown to prevent the use of VPN circumvention tools by demonstrators. The country's largest cellular provider, Econet, confirmed that the government issued a directive blocking all internet access during the protests. After the protests ended the Zimbabwean High Court ruled that the internet shutdown was illegal and ordered it to be restored.
On the third day of the protests, civil society activist and pastor Evan Mawarire was arrested. Mawarire's lawyer stated that the government alleged that his inciting of violent protests on Twitter as the reason for the arrest. The Movement for Democratic Change – Tsvangirai (MDC-T) stated that its party leadership had been detained by security forces during the protests. An unknown number of abductions by security personnel were reported during the crackdown on the protests.
The government blamed the MDC-T for the protests. MDC-T offices were attacked and torched during the protests with the MDC-T alleging that ZANU-PF supporters were responsible. The government stated that government property and property owned by the ruling ZANU-PF party was damaged in the attacks and blamed MDC-T supporters. The government also stated that the protests were coordinated by opposition parties and compared the protests to terrorism. The MDC-T denied government accusations that they were responsible for violence committed by protesters and highlighted acts of violence committed by government forces against protesters and civilians. A large number of the police raids took place in opposition electoral strong holds in urban areas around Harare.
On 17 January in Harare, the fourth and final day of fixtures in round three of the 2018–19 Logan Cup cricket tournament were both called off due to the protests.
After the protests
By Saturday the 20 January the security services set up a number of roadblocks throughout the country in an effort to arrest protesters and other individuals wanted by the government. A large number of people who disappeared during the government crackdown during the protests remain unaccounted for.
On 21 January, human rights organizations in Zimbabwe claimed that a total of 12 protesters were killed by security forces and many more had been beaten.
Response
Regional response
The MDC-T called on South Africa to intervene and criticise the government's violent response. Human Rights Watch stated that the use of unlawful lethal force by the government should be investigated and those responsible prosecuted. Zimbabweans in South Africa demonstrated to encourage South Africa to put pressure on the government to release arrested opposition leaders, restore internet access, and respect human rights. Protests by Zimbabweans against the Zimbabwean government response were also reported in Botswana and Namibia.
South Africa's official opposition party, the Democratic Alliance, stated that the situation within Zimbabwe was so severe that the South African government should abandon its Mbeki-era quiet diplomacy policy and intervene. The Economic Freedom Fighters, a South African political party, issued a statement condemning the Zimbabwean government's violent response to the protests. The South African government said it was monitoring the situation in Zimbabwe and stated with confidence that "measures being taken by the Zimbabwean government will resolve the situation."
The South African Federation of Trade Unions condemned both the fuel price increase and the government's use of lethal force against the protesters. The National Union of Namibian Workers stated that they were "saddened and disturbed by the blatant disregard for trade unions and human rights in Zimbabwe" and criticised the silence of the Southern African Development Community (SADC).
Human Rights Watch criticised the SADC and the African Union for remaining silent on the violations of human rights by the Zimbabwean government during the protests.
International response
embassy in Zimbabwe stated that it was "alarmed by credible reports that security forces are targeting and beating political activists and labor leaders". The embassy also urged the government to restore access to social media and for peaceful protests.
summoned the Zimbabwean ambassador to express its concern over the unrest and called on Zimbabwe to "ensure its security forces act professionally, proportionately and at all times with respect for human life".
criticised the disproportionate use of "force by security personnel" and stated that it expected "the Government of Zimbabwe to uphold human rights and the rule of law, as enshrined in the constitution, and ensure due legal process for those detained."
High Commissioner for Human Rights urged the government to "stop the crackdown" and stated its concern over the security forces' "excessive use of force".
See also
2017 Zimbabwean coup d'état
Economy of Zimbabwe
List of fuel protests
References
Protest
Zimbabwean
January 2019 events in Africa
Protests in Zimbabwe
Petroleum politics
Fuel protests
Labour disputes in Zimbabwe | Zimbabwe fuel protests | [
"Chemistry"
] | 1,583 | [
"Petroleum",
"Petroleum politics"
] |
59,679,523 | https://en.wikipedia.org/wiki/Nubia%20X | The Nubia X is an Android smartphone which was launched on 31 October 2018.
Given the tendency in the late 2010s toward bezelless displays, instead of trimming the display with a notch or hole for housing a front camera, it opts to use two screens (on both sides of the phone). Selfies and videocalls are made with the main camera and the rear display as viewfinder.
References
Android (operating system) devices
Discontinued flagship smartphones
Mobile phones introduced in 2018
Mobile phones with multiple rear cameras
Mobile phones with 4K video recording | Nubia X | [
"Technology"
] | 113 | [
"Mobile technology stubs",
"Discontinued flagship smartphones",
"Flagship smartphones",
"Mobile phone stubs"
] |
59,679,582 | https://en.wikipedia.org/wiki/NGC%204060 | NGC 4060 is a lenticular galaxy located 320 million light-years away in the constellation Coma Berenices. It was discovered by astronomer Albert Marth on March 18, 1865 and is a member of the NGC 4065 Group which is part of the Coma Supercluster.
NGC 4060 is classified as a LINER galaxy.
See also
List of NGC objects (4001–5000)
References
External links
4060
38151
Coma Berenices
Astronomical objects discovered in 1865
Lenticular galaxies
LINER galaxies
Discoveries by Albert Marth
NGC 4065 Group | NGC 4060 | [
"Astronomy"
] | 111 | [
"Coma Berenices",
"Constellations"
] |
59,679,805 | https://en.wikipedia.org/wiki/Vivo%20NEX%20Dual%20Display | The Vivo NEX Dual Display is an Android smartphone which was launched on 11 December 2018. Given the tendency in the late 2010s toward bezelless displays, instead of trimming the display with a notch or hole for housing a front camera and face recognition sensor, it opts to use two screens (on both sides of the phone). Selfies and videocalls are made with the main camera and the rear display as viewfinder.
Reviews
It has been described as a "wow" flagship device and "an unusual concept executed well".
References
Android (operating system) devices
Mobile phones introduced in 2018
Mobile phones with multiple rear cameras
NEX 2
Mobile phones with 4K video recording
Discontinued flagship smartphones | Vivo NEX Dual Display | [
"Technology"
] | 143 | [
"Mobile technology stubs",
"Discontinued flagship smartphones",
"Flagship smartphones",
"Mobile phone stubs"
] |
59,680,063 | https://en.wikipedia.org/wiki/Human%20satellite%20II | Human satellite II is an exceptionally high-copy but unexplored sequence of the human genome thought of as junk DNA has a surprising ability to impact master regulators of our genome, and it goes awry in 50 percent of tumors.
Because HSAT-II DNA is normally methylated (a form of gene regulation), it remains dormant in healthy cells. For this reason, the HSAT-II hasn't been extensively studied and has not been thought to have a function. Due to its similarities to Human Satellite 3, the primary sequence component of the traditional human satellite fraction II (also known as Human Satellite 2 or HSat2) is sometimes incorrectly marked by RepeatMasker. In RepeatMasker annotations, both repeats frequently appear as a mixed pattern of "HSATII" and "(CATTC)n simple repeats." Based on this problem, Oxford Nanopore Technologies researcher used their own characterization of these sequences inside the CHM13 genome To further classify each HSat2 array into its previously identified subfamilies.
In fact, standard genomic experiments intentionally screen HSAT-II out of the results. Both herpes viruses and cancer manipulate this same pathway causing genetic instability and disease.
References
DNA
Gene expression
Non-coding DNA | Human satellite II | [
"Chemistry",
"Biology"
] | 255 | [
"Gene expression",
"Molecular genetics",
"Cellular processes",
"Molecular biology",
"Biochemistry"
] |
59,681,101 | https://en.wikipedia.org/wiki/Plant%20blindness | Plant blindness is a proposed form of cognitive bias which, in its broadest meaning, is a human tendency to ignore plant species. This includes such phenomena as not noticing plants in the surrounding environment, not recognizing the importance of plant life to the whole biosphere and to human affairs, a philosophical view of plants as an inferior form of life to animals, and/or the inability to appreciate the unique features or aesthetics of plants. Related terms include plant‐neglect, zoo-centrism, zoo‐chauvinism, or a lack of plant literacy.
The term plant blindness was coined by the botanists educators J. H. Wandersee and E. E. Schussler in their 1999 publication 'Preventing Plant Blindness'. Scientists have suggested that the reason some people don't notice plants is because plants are stationary and similarly coloured, although other research has suggested that plant blindness is affected by cultural practices. A 2014 study in the United States looked at how plants and animals are perceived using "attentional blink" (the ability to notice one of two rapidly presented images). The study showed that participants were more accurate in detecting animals in images, rather than plants. The researchers also suggested possible strategies for characterizing and overcoming zoo-centrism.
According to the BBC journalist Christine Ro, plant blindness is potentially linked to nature deficit disorder, which she construes is causing what she claims is reduced funding and fewer classes for botany.
Causes
Two main avenues through which plant blindness has arisen have been suggested: human nature, and culture.
Human nature
The first, human nature, encompasses the idea that human brain chemistry and visual processing systems are inherently biased to ignore plants in the environment. Studies have shown that human visual systems can not effectively process all the information that is seen. Thus, research suggests that priority is given to variable colors, movement, and familiar objects in order to most effectively detect threats and potential food sources. As plants do not often fit this criterion, many scientists think the human brain tends not to fully process their visual presence. Additionally, primates have been shown to have a preference for organisms that behave similarly to their own species. As plants behave very differently than humans, this also suggests that there is an intrinsic component to plant blindness.
Culture
Culture has also been shown to play an important role in the establishment of plant blindness in a society. Many believe that evidence for this is found in the decreased level of plant blindness in certain communities. For example, in certain Indian and indigenous communities, plants are highly valued for their role in religion, medicine, and mythology.
In societies where plant blindness is prevalent, several cultural mechanisms are considered to contribute to the phenomenon. Zoo-centric education is considered to be one main cause. In the United States, high school biology textbooks devote only 15% of their content to plants. In many societies, there is not thought to be a comprehensive understanding among citizens of the complexity behind plants' behaviors, reactions, and movements. The pervasive misunderstanding of evolution as a linear mechanism where humans are most evolved and plants are least evolved, rather than as a complex, non-hierarchical process, may also cultivate plant blindness. Plant blindness is also partially attributed to increased urbanization, which has led to nature-deficit disorder and the decrease in prominence of plants' roles in everyday life. Finally, the concept that animals are more important than plants is reinforced through cultural over-representation of animals, such as in mascots.
Potential effects
Several concerns exist regarding the potential effects of plant blindness. Most notably, plant blindness may lead to less funding being available for plant conservation efforts. Plants make up 57% of the endangered species list, while only 3.9% of funding for endangered species is allotted to them.
Laws do not protect endangered plants as well as endangered animals. Endangered plants on Federal land are protected, but landowners can destroy them on their private property. Many states have no state level laws to protect endangered plants.
Plant blindness is also thought to have led to a deficit in plant science research and education. Plant science research has been defunded, interest in botany majors has decreased, and plant biology courses have been terminated in recent years. Yet, this plant research is believed to be critical for medicinal and agricultural advancement.
Efforts to combat plant blindness
Several methods have been proposed to combat plant blindness and efforts are on-going. The most prominent campaign addressing this issue is called Prevent Plant Blindness and was created by Wandersee and Schussler, the researchers who coined this term. This campaign uses three main types of advocacy: a classroom poster which has been distributed to 20,000 teachers and endorsed by the Botanical Society of America, a children's mystery picture book about a plant, entitled Lost Plant!, and promotion of plant-growing education, including school-gardens.
Several other suggestions to address the cultural component of plant blindness have also been proposed. Research has shown that creative activities involving plants, such as storytelling, art, and role-playing can help to strengthen children's relationships to plants. Increasing the representation of plants in science education textbooks, specifically those for high school biology has also been encouraged. Spreading awareness about plant blindness may help reduce it, as the first step in reducing one's biases is thought to be acknowledging them. Citizen science projects involving plants, such as TreeVersity, attempt to help non-botanists see plants in more variable and frequent ways. Plant representation in art and in fictional characters, such as Groot, is considered to be a part of the solution, as well as ensuring plant education employs best practices. Particularly, it has been suggested that plant education should employ constructivist principles, active learning, and multimedia instruction. Finally, plant activists suggest that humans should be considered as a part of the natural system, rather than outside and above it.
Disagreement about the term
Some disagree with the use of this term, asserting that human bias against groups of species extends to all organisms without backbones and human-like eyes. Much of the biodiversity on Earth is found in insects, such as beetles, yet few insects are represented in biology education and in media. Thus, some argue that this phenomenon is more accurately the tendency of humans to ignore everything except vertebrates, not just plants.
Others take issue with the name of the phenomenon, as they consider the use of a disability, blindness, inappropriate as a descriptor of a negative trait and have suggested the name Plant Awareness Disparity (PAD).
See also
Speciesism
References
Plants and humans
Bioethics
Cognitive biases | Plant blindness | [
"Technology",
"Biology"
] | 1,318 | [
"Bioethics",
"Plants and humans",
"Plants",
"Ethics of science and technology",
"Humans and other species"
] |
74,749,187 | https://en.wikipedia.org/wiki/Fronti%C3%A8re%20de%20fer | Frontière de fer or pré carré is the name given in military historiography to the double line of fortresses that king Louis XIV of France had constructed after the Peace of Nijmegen in 1678 to protect what was then Northern France against foreign invasion, and to be used as operational bases against foreign enemies in the years of the Nine Years' War and the War of the Spanish Succession. This system of defensive lines was later extended to a so-called Ceinture de fer (Iron Belt) that also encompassed similar systems along the eastern and southern borders of France. The alternative term pré carré may be based on a misunderstanding. The term pré carré was first used by the French military engineer Sébastien Le Prestre de Vauban in a letter to the French minister of war François Michel Le Tellier de Louvois of January 1643 in which he wrote:
In this quote Vauban not only introduced the term pré carré that can be variously translated, depending on the context, but more importantly, for the first time formulated the strategic vision that would later be the basis for the frontière de fer as a military architecture. He may have been inspired by the so-called Oud-Hollands vestingstelsel (Old-Dutch system of fortresses), a multi-tiered ring of fortresses around the core of the Dutch Republic, that had been constructed since 1629 in the last stage of the Eighty Years' War, and that culminated in the Dutch Waterline that frustrated the final push of the French offensive in late 1672.
Vauban envisioned (like in the Dutch example) a tiered set-up, like in a contemporary order of battle. To attain this objective he suggested to Louvois not just which enemy fortresses to take and retain, but also which ones to bypass, and which eventually to discard (after demolishing them). His strategic ideal thus guided him both in the conduct of offensive war and in the peacetime construction of new fortified locations. He intended his barriers not as flexible defenses, but as "...seals designed to preserve the sacred land of France. The pré carré demanded the rationalization of French frontiers, not just the building of ever more fortifications. Vauban often spoke of abandoning and razing existing fortifications, as well as building new ones."
The term frontière de fer was apparently coined by Lazare Carnot in a later stage. Officially the system was referred to as the règlement des places frontières (regulation for the border places).; the other designations were given by later historians. Though Vauban can claim to be the originator of the concept, others (primarily Louvois, and possibly the king himself) decided the final shape the system would take over many years. However, Vauban was the architect of many, if not all, of the fortresses that would become part of the system. According to the principles he developed in his
Mémoire, pour servir d'instruction dans la conduite des sièges et dans la défense des places (1670) and worked out in many later such mémoires, he sought to adapt each individual design to the characteristics of the local landscapes, taking advantage of local features, where possible. As Commissaire general des fortifications he was in charge of the actual construction of the system after 1677 and until his death in 1707. He therefore did not see the system in its final form, which it briefly achieved after 1708, before it was broken up again in the immediately following years.
The system spanned the area between the sea at Dunkirk to Dinant at the border of the Prince-Bishopric of Liège, a neutral state at the time. It is a landscape that is relatively open to maneuver warfare, even though many rivers run through it. This unlike the area to the East, which is far more difficult to maneuver in, and so forms a natural border. Hence the need to form a non-natural defensive barrier in it. Vauban aimed at forming in the center of the plain a strong center from which the army could resist the invading enemy from the front and threaten him on his flanks if he tried to bypass that position, and from which the army could take the offensive also. To construct such a position Vauban sought to take advantage of natural obstacles, like rivers, canals and military inundations. It consisted of a "first" or "northern" line of fortified places, centered on Mons, Condé and Tournai, with in front of that the fortress of Ath. Behind this first line in the center, a second line was envisaged, consisting of Douai, Arras, Valenciennes, Bouchain,Cambrai, Maubeuge, Landrecies, and Le Quesnoy. To the right of this central sector we find Namur, Charleroi, Philippeville, Mariembourg, Avesnes, Rocroi, and Charlemont. On the Western part of the line we find Nieuwpoort, Fort Knokke, Ypres, and Menen.
The system was developed while wars were going on in the area in question. Consequently, the places mentioned above often changed hands. In 1701, when the War of the Spanish Succession started, France possessed all of them, but in the course of the war more and more were lost to the opponents of France in that War. After the Peace of Utrecht a number of these places were permanently removed from the French sphere of influence, and ironically a number of those places became part of the Barrier created by the Barrier treaties that were intended to defend the Dutch Republic against French encroachment after 1715. Knokke, Ypres, Menen, Tournai, Mons and Namur so became part of the defensive line of fortresses that protected France's enemies.
Notes
References
Sources
Historic defensive lines
War of the Spanish Succession
17th-century fortifications
Forts in France
Forts in Belgium
18th-century fortifications | Frontière de fer | [
"Engineering"
] | 1,225 | [
"Fortification lines",
"Historic defensive lines"
] |
74,749,311 | https://en.wikipedia.org/wiki/Barium%20nitrite | Barium nitrite is a chemical compound, the nitrous acid salt of barium. It has the chemical formula Ba(NO2)2. It is a water-soluble yellow powder. It is used to prepare other metal nitrites, such as lithium nitrite.
Synthesis
Barium nitrite can be made by reacting barium nitrate with lead metal sponge, or by reaction of lead nitrite with barium chloride.
Safety
Barium nitrite is toxic if ingested or inhaled, as both barium and the nitrite ion are toxic.
References
Inorganic compounds
Barium compounds
Nitrites | Barium nitrite | [
"Chemistry"
] | 129 | [
"Inorganic compounds"
] |
74,749,516 | https://en.wikipedia.org/wiki/Sirobasidium%20magnum | Sirobasidium magnum is a species of fungus in the order Tremellales. Basidiocarps (fruit bodies) are gelatinous, lobed to foliose (leaf-like) and appear to be parasitic on ascomycetous fungi on wood. No other Sirobasidium species has such large fruit bodies. The species was originally described from Indonesia, but has been reported from elsewhere in Asia and also in Australia and North America.
Taxonomy
Sirobasidium magnum was described from Borneo and Java in 1934 by Dutch mycologist Karel Boedijn.
Description
Fruit bodies are gelatinous, lobed and folded, and orange-brown. measuring up to 45 mm across. Basidia are catenulate (formed in chains), with up to 8 basidia in each chain. Individual basidia are oval to fusiform and transversely 2-4-septate. The sterigmata are deciduous, fusiform, 15-19 x 4-5 μm. The basidiospores are globose, 7-9 μm across.
Habitat and distribution
Sirobasidium magnum was originally described on rotten wood, but is possibly parasitic on fungi in the genus Hypoxylon growing on dead attached or fallen wood. Sirobasidium magnum has been recorded from Asia (China, Indonesia, Japan, Korea, Malaysia, Philippines, Singapore, Taiwan, Thailand), Australia, the Seychelles, Tahiti, and North America (USA).
References
Tremellomycetes
Parasitic fungi
Fungi described in 1934
Fungi of Asia
Fungus species | Sirobasidium magnum | [
"Biology"
] | 328 | [
"Fungi",
"Fungus species"
] |
74,749,576 | https://en.wikipedia.org/wiki/Avant%20Slant | Avant Slant (subtitled One Plus 1 = II?) is an album by American jazz ensemble the John Benson Brooks Trio, released in September 1968 by Decca Records. Produced by Decca A&R executive Milt Gabler, it was pianist and bandleader John Benson Brooks' third and final released recording, arriving ten years after his previous record, the acclaimed Alabama Concerto (1958).
The record is a sound collage that draws from several primary sources, namely The Twelves–a 1962 live performance by Brooks' ensemble in which they improvised within the twelve-tone technique–and D.J.-ology, a musique concrète tape that Brooks privately created which consisted of numerous sound effects, one-liners and excerpts of records and radio broadcasts. Gabler contributed additional pop songs to the final album, which he largely created himself. The record uses the Brooks trio's dissonant live music as a backbone while cutting to sampled audio and recordings of poetry, comedy, spoken comments, speeches and found sounds. Themes of war, racism, identity and personal freedom underpin the record.
On release, Avant Slant was a critical and commercial disappointment. Although reviews ranged from positive to negative, many expressed puzzlement at the record. Some critics and listeners who enjoyed Brooks' prior work in experimental jazz found that The Twelves material was devalued by the presence of the pop culture-centric D.J.-ology snippets. Despite this, the album has gone on to be credited as a prophetic release in the fields of sampling and mashups.
Background and recording
Prior to Avant Slant, John Benson Brooks had spent many years working as a pianist and arranger. His only two previous albums were Folk Jazz USA (1956), part of a personal project to adapt folk music idioms into modern jazz, and Alabama Concerto (1958), the hybrid of jazz, folk and contemporary composition that became his most critically acclaimed work. After 1958, the musician's music became more experimental and he largely disappeared from the public eye for many years. In 1962, Brooks' jazz trio (pianist Brooks, alto saxophonist Don Heckman and percussionist Howard Hart) were commissioned to write a piece to perform at the International Jazz Festival at Howard University. The resulting performance, named The Twelves, was the culmination of Brooks' experiments in improvising jazz in the twelve-tone serial and chance idioms. Heavily influenced by Ornette Coleman, it was ultimately the trio's only public show.
The genesis of Avant Slant came when Brooks created a tape entitled D.J.-ology, described by John Clellon Holmes as "a curious melange of air-shots, record excerpts, sound effects and one-liners that Brooks had put together, more or less experimentally". The tape also included other sounds which Brooks had recorded off disc jockey radio programs. Intended as a Christmas present for Heckman and composer George Russell, D.J.-ology exemplified Brooks' longtime interest in "the possibilities of using the tape recorder as a musical instrument." He had already created works of musique concrète, including a late 1940s piece created with a wire recorder to "capture moments that seemed like 'emblems' of favorite jazz recordings and stringing them together with environmental sounds", according to author Phil Ford. Brooks later studied with John Cage and composed Bird Meets Cage, which combined his passions for musique concrète and chance procedures by mixing clips of his and Heckman's atonal jazz with excerpts from electronic music albums.
In 1966, Brooks conceived the idea of creating "meta-music", or music as "a play of competing -isms," which, according to Ford, led the composer "to the idea of embodying those -isms in audio clips and making an album out of them". This resulted in Avant Slant, based in Brooks' improvised twelve-tone jazz system and the "pop-art musique concrète" of his "DJology". He had partly financial motivations, as he hoped to earn enough money to account for his mother's medical bills and to "contribute something to his household economy." The record was a collaboration between Brooks and producer Milt Gabler, who worked as an A&R executive at Decca Records. Brooks gave Gabler tapes of both The Twelves and D.J.-ology. Gabler then created much of the album; he added some of his own recordings and, according to Ralph J. Gleason, "let them sit for months while he played with them" before finally arriving at the finished album. Ford credits Gabler for finding the majority of the records's samples, sequencing most of its parts, writing lyrics for five of its six original songs and conceiving the "quick lines and snatches of dialogue read by actors" that also appear. An early problem was managing the costs of licensing all the intended audio excerpts, which was sometimes averted by Gabler re-recording clips he was unwilling to pay for.
Composition
Avant Slant is a sound collage, described by Gabler as a "twelve tone collage", which uses excerpts of The Twelves and D.J.-ology tapes and Gabler's additions to create what Gleason calls "a kind of kaleidoscope sound montage of contemporary America knotted together by the improvisations of the jazz trio of Brooks and the songs of Gabler." Author David Toop describes it as a "disrupted, haphazard narrative" in which the "intense angularity" of the trio's live playing is "intercut with recordings of comedy routines, poetry, piano solos and songs performed by singers such as Judy Scott, Lightnin' Hopkins, The Tarriers and Corrine." Burgess calls it an experimental work and "collage of sound" that uses the trio's dissonant music, non-musical sounds and "fragments of poetry, bits of pop tunes, broadcasts, spoken comments and instrumental snatches". Ford describes it as "an assaultive mix of atonal jazz, Tin Pan Alley songs, poems, found sounds, and non sequitur lines read by ham actors". The record has also been categorized as jazz and a mixed-media collage. The 1962 Brooks ensemble performance forms the spine of the album.
The different source materials are often presented in a linear and consecutive manner without any layering. In Toop's description, the album's subject matter covers an array of late 1960s concerns, including "spaceflight, sexual liberation, the Vietnam war, racism and civil rights, identity and personal freedom". He adds that these themes are accentuated by poems and speeches that "range from Herman Goering's 'guns and butter' speech justifying Nazi Germany's rearmament policy in 1936 to a brief excerpt from Black Dada Nihilismus, Amiri Baraka's violent verbal assault on white imperialist civilisation". Gleason highlights the use of poetry from Lawrence Ferlinghetti and John Donne and snippets of voice which "sound like (and perhaps are) Lord Buckley, Everett Dirksen, Dean Martin, LBJ, George Wallace and others." Furthermore, Gabler wrote several show tune-style ballads for the record, sung by Scott with Brooks' music, lifted some ragtime music from an early Decca release and added portions of "We Shall Overcome" and Malvina Reynolds' "Little Boxes" (1962) and works from critic Seymour Krim and LeRoi Jones.
In Ford's description, Brooks used Avant Slant to envision, represent and adapt to "the pop postmodernity that buried his native culture of Cold War modernism", and believed it to be "more way-out" than contemporary listeners could realize. David Atkinson compared the album to early 1960s jazz poetry, except that all the components on Avant Slant are "shortened down to mere fragments of an entire section." Toop writes that although the record is musically and politically serious, it is "still descended from radio drama and the novelty break-in records". In Marianna Ritchey's estimation, the record's combination of music and recorded soundscapes was merely one assortment of ideas from Brooks' archival work and, as Ford argues, thus could only be understood by Brooks.
Release and reception
Avant Slant was released by Decca in September 1968 with a psychedelic album cover and liner notes by John Clellon Holmes. Brooks' final released recording, it sold very poorly and received few reviews; according to Ford, "what notices it did get were either respectful or dismissive but in any event puzzled. Avant Slant was the overcooked product of ten years’ private study and musical experimentation, and there was no public context for it." Critics and listeners who endorsed Brooks' experimental jazz work believed that the pop cultural nature of the album's D.J.-ology elements devalued The Twelves, including Gil Evans, who dismissed them as "entertainment". Brooks predicted these reactions, as – according to Ford – the record was a product of the moment where "jazz intellectuals could feel themselves being shoved aside by a new pop culture that did not share their modernist values."
Martin Wiliams of Saturday Review praised the Brooks ensemble's original performance, noting the humor, swing and conviction in their playing, but dismissed Avant Slant for intercutting portions of the concert with "stilted, unfunny verbal gaggery, sound effects, snippets of other music, quasi-poetry, 'mod' verbiage, and a few conventionally conceived pop tunes." He added that despite the liner notes describing the album as a work for "Right Now", what he wanted was "to be able to listen to it tomorrow". A reviewer for Coda similarly dismissed the D.J.-ology segments as "ultra-hip, pretentious, money-grubbing, and several other things the editor would not be allowed to print." In their review, Cash Box commented that Avant Slant provides "a highly unusual listening experience" in which the four twelve-tone jazz improvisations are "broken up to allow space for 'ghost-voices' of contemporary figures, which reflect today's complex confusions."
In The San Francisco Examiner, Gleason believed it to be an innovative and "impressive performance" that pushed the boundaries of the album format further back following the Beatles' Sgt. Pepper's Lonely Hearts Club Band (1967), with regards to using it as a single artistic entity from start to finish rather than a reproduction of a live performance or a straight musical program. He considered there to be "flashes of real genius" on the record and concluded that it could help broaden the appeal of the album medium to young people who had been increasingly using film to express their worldviews. Paul Burgess of The Press of Atlantic City wrote that the album "seeks a rational whole out of irrational components" and compared it to the "surrealistic fur-lined tea cups" of Dadaism. He believed it to be a "turned on affair that will strike you as either a relevant piece of art or as a big put-on, depending on how you view such things." Similarly, David Atkinson of The Kansas City Star described it as a "montage of social comment and musical experimentation, but there are many elements of each which can be enjoyed, depending on the listener's point of view."
Legacy
Despite the critical and commercial failure of Avant Slant, it has been credited with anticipating "aspects of collage, mashup, and sampling." Duncan Heining of All About Jazz has listed Avant Slant as an example of jazz that experiments with electronics. In 1999, Heckman wrote in The Los Angeles Times that the album had become "hard-to-find". Retrospectively, AllMusic have named Avant Slant an "Album Pick". The authors of The Essential Jazz Records Volume 2 (2000) highlight Brooks and Heckman's work in improvisation and composition, but believed that Avant Slant presented them "in an extremely unsatisfactory manor", due to how it mixes segments of their music with excerpts of pop, poetry and radio broadcasts "in ways that make it impossible to decide what they had achieved and whether there was a further potential."
Academic writer Casey Nelson has called it a "deeply strange jazz/pop/found-sound fusion album".
Track listing
Side one
– 10:41
"The King Must Go" (Segments) (John Benson Brooks)
"The Gods on High" (Brooks, Milt Gabler)
"Pie in the Sky" (Brooks, Gabler, lyrics by John Donne)
"El Bluebirdo" (Brooks)
"A Bird Can Be" (Gabler)
– 12:11
"Cherries Are Ripe" (Brooks)
"What's a Square?" (Brooks, Gabler)
"Slapstix" (Jack Shaindlin)
"True Blue Heart" (Shaindlin)
"Little Boxes" (Excerpt) (Malvina Reynolds)
"But, Where Are You?" (Brooks, Gabler)
Side two
– 13:07
"Ornette" (Segments) (uncredited)
"Love Is Psychedelic" (Brooks, Gabler)
"The Life I Used to Live" (Lightnin' Hopkins)
"When I First Came to To Town" (uncredited)
"Mend Them Fences" (Brooks, lyrics by Robert Graves)
"But, Where Am I?" (Brooks, Gabler)
– 9:38
"Satan Takes" (Segments) (Brooks)
"Pie in the Sky" (Brooks, Gabler, lyrics by Catherine Lee Bates)
"We Shall Overcome" (Thomas Jefferson)
Excerpt credits
Sammy Davis Jr. – Sammy Davis Jr. at Town Hall
Jack Shaindlin – piano solo portions from 50 Years of Movie Music
The Tarriers – "Little Boxes"
Seymour Krim – The Magic Underwear Panty (with Detachable Garters)
Lawrence Ferlinghetti – Autobiography
Carl Sandburg – The People, Yes
LeRoi Jones – Black Dada Nihilismus
Lightnin' Hopkins – "Life I Used to Live"
Personnel
Adapted from the liner notes of Avant Slant.
The John Benson Brooks Trio
John Benson Brooks – piano
Don Heckman – alto saxophone
Howard Hart – snare drum, cymbal
Others
Milt Gabler – producer, editing supervisor
Ernie Stone – voice actor
Herb Hartig – voice actor
Jack Gibson – voice actor
Joyce Todd – voice actor
Judy Scott – voice ("The Gods on High", "What's a Square?", "But, Where Are You?", "But, Where Am I?")
Lawrence Ferlinghetti – voice ("El Bluebirdo")
Jack Shaindlin – piano ("Slapstix", "True Blue Heart")
The Tarriers - performer ("Little Boxes" (Excerpt))
Frank Hamilton – voice ("We Shall Overcome")
Guy Carawan – voice ("We Shall Overcome")
LeRoi Jones – voice ("We Shall Overcome")
Pete Seeger – voice ("We Shall Overcome")
Zilphia Horton – voice ("We Shall Overcome")
Emil Korsen – engineer
George Chandler – engineer
Joseph Curran – engineer
Rudy May – engineer
Joan Franklin – recording
Robert Franklin – recording
Steinweiss – cover
John Clellon Holmes – liner notes
Notes
References
Bibliography
1968 albums
Decca Records albums
Albums produced by Milt Gabler
Pete Seeger
Sound collage albums
Experimental music albums by American artists
Jazz albums by American artists
Pop albums by American artists
Musique concrète albums
Field recording
Postmodern music
Twelve-tone compositions | Avant Slant | [
"Engineering"
] | 3,214 | [
"Audio engineering",
"Field recording"
] |
74,750,400 | https://en.wikipedia.org/wiki/Gallic%20horse | Gallic horse (Equus caballus gallicus) is a prehistoric subspecies of Equus caballus (the horse) that lived in the Upper Paleolithic. It first appeared in the Aurignacian period because of climatic changes and roamed the territory of present-day France during the Gravettian and up to the end of the Solutrean. Its fossils, dated from 40,000 to around 15,000 years BC, are close to those of Equus caballus germanicus (the Germanic horse) and may not correspond to a valid subspecies. First described by François Prat in 1968, it is around tall and differs from Equus caballus germanicus mainly in its dentition and slightly smaller size.
Validity status
There is no consensus among specialists as to the validity of the subspecies Equus caballus gallicus. Based on paleontological discoveries at numerous sites in present-day France, such as Solutré, Camiac and La Quina, François Prat postulates that Equus caballus gallicus gradually replaced Equus caballus germanicus and that the two subspecies are distinct. On the other hand, Véra Eisenmann, a CNRS and MNHN researcher, postulates that the specimens attributed to Equus caballus gallicus do not present a sufficiently distinct variation from the subspecies Equus caballus germanicus. However, it is accepted that Equus caballus arcelini, a well-differentiated subspecies, has replaced the populations made up of specimens traditionally attributed to Equus caballus germanicus and Equus caballus gallicus.
Discovery and taxonomy
The discovery of this subspecies followed the examination of horse bones found at Solutré and recovered by Jean Combier. Noting differences in morphology associated with different dating (suggesting different species or subspecies among these fossils), François Prat and Combier postulated the existence of two differentiated types of horse on this site: Equus caballus gallicus and Equus caballus arcelini. The name chosen refers to the territory that Equus caballus gallicus occupied, Gaul. Because it forms most of the fossils found at Solutré, Equus caballus gallicus is generally referred to by the still-common name of "Solutré horse". It is considered a subspecies. As the evolutionary history of Equidae remains controversial, it is sometimes (rarely) considered a species of the genus Equus, named Equus gallicus.
Not all prehistorians and paleontologists recognize the existence of this taxon. Vera Eisenmann postulates that Equus caballus germanicus can show variations in size and dentition, and therefore that Equus caballus gallicus never existed. According to her, Equus caballus arcelini would have succeeded Equus caballus germanicus directly 15,000 years BC, with much more visible morphological changes.
Description
Evolutionary history
According to a theory put forward by N. Spassov and N. Iliev in 1997, it would seem that "cut off from the parent population in northern and central Europe by climatic barriers, Equus (caballus) germanicus evolved into gallicus and then arcelini in western Europe", while horses in eastern and southeastern Europe evolved differently. According to Vera Eisenmann, the transition from Equus caballus germanicus to gallicus appears to have been gradual, accompanying changes in the biotope. As horses eat more and more grasses, their dentition changes.
Appearance and skeletal characteristics
Equus caballus gallicus was first described by François Prat in 1968. Smaller than Equus caballus germanicus ( on average), it has a different morphology, with more pronounced caballins characters on its dentition. It is also lighter than the latter, with broad hooves and a short, voluminous head with strong teeth, resting on a short, broad neck. Based on cave paintings and primitive horses such as the Przewalski, specialists attribute a dun or pangaré coat (light brownish-yellow, black manes and tips, discoloration of the underside).
Period
Equus caballus gallicus appeared after the first half of Würm III. It is inseparable from the Aurignacian and Gravettian periods. It lasted until the Solutrean and Magdalenian periods. Between 35,000 and 22,000 B.P., the climate in present-day France was cold or temperate. At this time, there were vast areas of grassland, ideal for herding horses. It is then possible that a new species or subspecies better adapted to climatic constraints succeeded Equus caballus gallicus in south-western France at the end of the Würm IV, but this question remains debated.
Biotope and ethology
Equus caballus gallicus preferred to live in "dry to compound steppe environments" with few hygrophilous plants, in cold, dry climates, where grass was abundant. Gregarious, it congregated in large herds and preferred large, open areas, enabling it to move quickly in search of meadows where it could feed. It tolerated wide temperature ranges, as well as temperate climates.
Locations
Equus caballus gallicus is common in southwestern France, particularly in Aquitaine, Périgord and Quercy. Its remains have been identified at various prehistoric sites, including Camiac (Gironde, 35,000 years BC) and Nespouls (Corrèze, 30,000 years BC). This subspecies generally succeeds Equus caballus germanicus, then is itself replaced by Equus caballus arcelini, associated with the Magdalenian.
Rock of solutré
Solutré is the first site where bones of this subspecies have been identified. Equus caballus gallicus appeared in the region in the second half of Würm III, as a successor to Equus caballus germanicus, which had been present since Würm II. Horses probably often passed close to the Rocher de Solutré during their seasonal migrations, overwintering in the Rhône and Saône valleys before moving west to the plateaus when the weather warmed up. Paleolithic human groups took advantage of the passage of numerous herds to slaughter animals.
Ardennes
In 1985, Jean-Pierre Penisson summarized the numerous prehistoric horse remains found in the Ardennes region. During the Würm II period, Equus caballus gallicus settled in the Dommery region. According to the Laboratory of Quaternary Geology and Prehistory at the University of Bordeaux 1, this horse could be the origin of today's Ardennais breed. For their part, Belgian researchers note that during the same period, Equus caballus germanicus was gradually supplanted by Equus caballus gallicus, which became a highly prized game animal by the end of the Upper Paleolithic. During the Holocene, horses became rarer in the region. The Ardennais (one of France's oldest horse breeds, and probably Europe's oldest draft horse) has long been considered a direct descendant of the Solutré horse, which lived in the Saône and Meuse basins in the 50th millennium BC and settled on schistose plateaus with a harsh climate at the same time. However, there is no evidence that horses from the Solutré site migrated to the Ardennes.
La Quina
Also at the La Quina site, Equus caballus gallicus succeeded Equus caballus germanicus. This evolution is probably linked to climatic changes. Radiocarbon dating puts it at around 43,000 years old, or 35,000 years old, the differences perhaps being due to the lack of precision of this method.
Tournal cave
Located in the commune of Bize-Minervois in the Aude department, this cave also shows a transition between the two subspecies, dated at around 33,000 years BC, and therefore later than La Quina. Most of the bones found belong to Equus caballus gallicus.
See also
Evolution of the horse
References
Bibliography
Articles
Thesis
Papers
Horse subspecies
Horse anatomy
Taxonomy (biology)
Prehistoric mammals
Fossils of France | Gallic horse | [
"Biology"
] | 1,722 | [
"Taxonomy (biology)"
] |
74,751,166 | https://en.wikipedia.org/wiki/Mahathir%20Science%20Award | The Mahathir Science Award is an award for outstanding contributions in science and technology that address issues related to the tropics. The Foundation was established 17 August 2004 in honour of the former Prime Minister of Malaysia Mahathir Mohamad. It is presented by the Mahathir Science Award Foundation.
Award-winners
Alimuddin Zumla
Hugh Possingham
Kerrie Wilson
Erik Meijaard
Rita R. Colwell
Alan Cowman
Yuan Longping
References
Mahathir Mohamad
Science and technology awards
Malaysian awards
Awards established in 2004
2004 establishments in Malaysia
Science and technology in Malaysia | Mahathir Science Award | [
"Technology"
] | 120 | [
"Science and technology awards",
"Science award stubs"
] |
74,751,376 | https://en.wikipedia.org/wiki/Ho-Young%20Kim | Ho-Young Kim is a mechanical engineer and an academic. He is a Professor and chair in the Department of Mechanical Engineering at Seoul National University.
Kim's research interests encompass fluid mechanics, biofluid dynamics, microfluidics, soft matter, and their applications in bio-inspired soft mechanics, biomimetic soft robotics, nanofluidics, and renewable energy. Among numerous awards, he is the recipient of SNU President's Research Excellence Award, Gasan Award for Research Excellence and the Namheon Award for Research Excellent from the Korean Society of Mechanical Engineers.
Kim is a Fellow of the American Physical Society. He has served as an Associate Editor for Droplet.
Education
Kim obtained his B.S. in Mechanical Engineering from Seoul National University in 1994. In 1996, he pursued an S.M. (Master of Science) in Mechanical Engineering at the Massachusetts Institute of Technology (MIT) in Cambridge and earned his Ph.D. in Mechanical Engineering from MIT in 1999.
Career
Kim began his career as a Senior Research Scientist as Military Service at the Korea Institute of Science and Technology from 1999 to 2004. During the military stint, he held positions as a Visiting Scholar at the Laboratory for Manufacturing and Productivity at the Massachusetts Institute of Technology (MIT) in 2001 and a Visiting Scientist at the University of Cambridge, in 2002. In 2004, he worked as a Postdoctoral Fellow in the Division of Engineering and Applied Sciences at Harvard University. He then joined Seoul University as an assistant professor in the same year and has held the position of Professor in the Department of Mechanical Engineering at the Seoul National University since 2014.
Kim has held numerous professional appointments, including Track Chair for the World Congress on Biomechanics 2022 and co-chair for the International Conference on Nature Inspired Surface Engineering 2020, and organizer for the IUTAM Symposium on Capillarity and Elastocapillarity in Biology 2024.
Research
Kim's research has focused on biofluid mechanics, capillarity, bubbles, nanofabrication, and soft matter, and has integrated experimental and theoretical approaches.
Biofluid mechanics
Motivated by the ability of water striders to jump off water surface without sinking, Kim studied how super-water-repellent solids can be disengaged from water. He showed that a tiny superhydrophobic sphere can bounce off water surface when it impacts onto water with speeds of a narrow range. By studying the force and energy required to lift a solid object clear from the water surface, he found that a drastic degree of energy saving (up to 99%) is achieved when lifting a superhydrophobic object as compared with an object with moderate wettability. He also obtained the load supported by small floating objects as a function of the contact angle, and the sinking speeds of small but heavy solids into either inviscid or viscous liquids. These hydrodynamic studies eventually allowed him to capture the essential physics behind water jumping of water striders and to build a robotic water strider. He has extended his interests to the jumps of terrestrial insects, and solved the motion of a simple jumper (elastic hoop) to predict its maximum jump height accurately. In addition to the locomotion of semi-aquatic arthropods, he studied thrust generation of flapping appendages of swimming robots and animals. He found a kinematic condition of a compliant, beating fin for maximizing the thrust of a robotic fish. He also found that flapping paddles, tails, and fins of ducks, standing dolphins, and starting fish generate thrust by forming a vortical structure different from a conventional starting-stopping vortex paradigm, which allowed him to construct a scaling law to predict the thrust of the flapping plate in the absence of a free stream velocity. He also obtained a universal scaling law for the lift of hovering insects through simple scaling arguments of the strength of the leading edge vortex and the momentum induced by the vortical structure. In addition, his collaborative work used a fluttering flag to devise a novel scheme to generate electric power based on triboelectrification.
Capillarity
Upon the basis of the pioneering theory of elastocapillarity, Kim continued to investigate the bending of thin elastic objects due to interfacial forces as they touch the liquid-fluid interface. He formulated the elastic deformation of elastic sheets under the line force of surface tension and the loading due to hydrostatic and Laplace pressures, and solved the free-boundary problem as the location of the meniscus is a part of the solution. The problems that he investigated include a two-dimensional paintbrush, a bubble-actuated paddle, and a floating flexible leg. He investigated the clustering behavior of micropillars and lamellae as a liquid film evaporates and pulls the solid structures together due to surface tension effects. He has also expanded this research to hygroscopic poroelastic structures, like paper, that deform with impregnation of water.
The development of micro- and nanofabrication technology has enabled the formation of microscopically rough surfaces with tailored topography. Such surface textures magnify either wettability or water-repellency of smooth surfaces, which used to be impossible. He investigated the dynamics of liquid drops deposited on superhydrophilic textured surfaces to find that the spreading dynamics are qualitatively different from those on smooth surfaces and obtained the various scaling laws that govern the hemiwicking dynamics. Noting that writing with ink involves the similar process of superwetting of rough surfaces (paper) from a moving source (pen), he mathematically analyzed the process of writing. He also showed the effectiveness of superhydrophilic surfaces in collecting water from humid air via dewing, and modeled the shape of large drops on superhydrophobic surfaces.
Using the micro- and nanofabrication technology, he also generated surfaces with super- wettability-contrast, such that superhydrophobic areas are surrounded by superhydrophilic area or vice versa. Liquid drops impacting on the micro-wetting patterned surfaces exhibit novel and even aesthetically pleasing dynamic behaviors, leading to the formation of various deposit morphologies such as radiating liquid spokes and liquid rings.
Bubbles
Focusing on the mechanism of ultrasonic cleaning, Kim showed through a high-speed visualization technique and verified theoretically that it is the pressure gradient locally generated by rapid bubble oscillations that removes particles on solid surfaces. Based on the understanding of the role of ultrasonic bubbles in cleaning and damaging of solid surfaces, he devised a scheme of ultrasonic cleaning that can preserve fragile nanostructures on semiconductor chips while removing contaminant particles. He identified the physical origins of micropattern damage caused by violently oscillating cavitation bubbles. In addition to ultrasonic cavitation bubbles, he studied dynamic behavior of relatively slow thermal bubbles, which have implications on microbubble-based MEMS devices as well as boiling heat transfer. Both fluid-dynamic and thermal measurements were carried out for a bubble that forms, grows and departs from a continuously powered microline heater, a tool to investigate the microbubble behavior with high temporal and spatial resolutions. He also demonstrated that bubbles consecutively formed by a continuously powered microheater and deflecting an adjacent cantilever beam can be used as an actuator in liquid environments.
Nanofabrication
Kim developed a surface modification technology that forms nanoscale roughness and lowers the surface energy on large areas at a low cost using plasma assisted chemical vapor deposition (PACVD) technique with a group of materials scientists. The collaboration led to a variety of functional surfaces including the surfaces with strong and robust superhydrophobicity,
with long-lasting superhydrophilicity, with tunable absorbability, and an array of tilted pillars resembling the footpad of a gecko lizard. He extended this technique to superhydrophobize cylindrical porous tubes in order to improve the efficiency of a desalination process called membrane distillation.
To overcome the inherent drawbacks of most nanofabrication technologies that modify or pattern two-dimensional surfaces, either planar (conventional technology) or curved (the aforementioned plasma-based technology), he developed a technology to build three-dimensional nanoscale objects by direct deposition of nanofibers. He showed that a nanoscale polymer solution electrojet can coil to form free-standing hollow pottery as the jet is focused onto a sharp electrode tip. He also fabricated free-standing walls using electrojets, which can be a fundamental technology to enable nanoscale three-dimensional printing.
Soft matter
Kim has worked on mechanical analysis, optimal design, and low-cost fabrication of soft-matter-based machines, which can shape-morph and locomote just as soft natural organisms. He has been particularly interested in hygroscopically responsive materials, which can swell by absorbing water. He reported a self-locomotive ratcheted actuator powered by environmental humidity, called hygrobot. He suggested a way to understand such system from the perspective of thermodynamic cycle analysis. Mechanical study of hygroscopic swelling of porous materials led to the birth of a new scientific branch of poroelastocapillarity, for which he wrote an authoritative review. He is also working on stimuli-responsive granular materials and growing soft systems structurally embedded with physical intelligence.
Awards and honors
2014 – Shinyang Young Investigator Award, SNU College of Engineering
2014 – Gasan Award for Research Excellence, Korean Society of Mechanical Engineers
2017 – Fellow, American Physical Society
2018 – Namheon Award for Research Excellence, Korean Society of Mechanical Engineers
2022 – SNU President's Award for Research Excellence
References
Mechanical engineers
Mechanical engineering
Massachusetts Institute of Technology alumni
Seoul National University alumni
Academic staff of Seoul National University
Fellows of the American Physical Society
21st-century engineers
Year of birth missing (living people)
Living people | Ho-Young Kim | [
"Physics",
"Engineering"
] | 2,038 | [
"Mechanical engineers",
"Applied and interdisciplinary physics",
"Mechanical engineering"
] |
74,751,456 | https://en.wikipedia.org/wiki/Ship%20of%20Harkinian | Ship of Harkinian is an unofficial source port of the 1998 Nintendo 64 video game The Legend of Zelda: Ocarina of Time that runs on Microsoft Windows, Linux, macOS, Wii U, and Nintendo Switch.
It was first released in March 2022 for Windows, four months after Ocarina of Time's source code was decompiled and released. Since then, Ship of Harkinian has received ports to Linux and macOS, and homebrew ports to Wii U and Nintendo Switch.
Updates to Ship of Harkinian have attracted media attention, as they often integrate options and features which aren't present in any official release of Ocarina of Time.
The title of the project is an allusion to the philosophical thought experiment Ship of Theseus, as well as the name of the King from The Legend of Zelda CD-i games, which were infamous for the internet memes spawned from them.
Development
Decompilation of Ocarina of Time
In November 2021, after 21 months of development, the Zelda Reverse Engineering Team (ZRET) successfully decompiled the executable to The Legend of Zelda: Ocarina of Time into human-readable code. While the decompilation project was principally carried out for the sake of documenting the game's creation and backend functionality, it also made possible the potential creation of source ports of Ocarina of Time, which would allow the game to be recompiled and run on platforms it wasn't originally developed for. Speaking to Ars Technica, ZRET member Rozlette stated that source ports were "outside the scope of what we do".
Early development and release
In June 2020, developers Jack Walker and Kenix discussed the potential of a PC port of Ocarina of Time based on the ZRET decompilation project's work; at the time, Ocarina of Time's decompilation was only 17% complete. Development on what would later become Ship of Harkinian began in November 2021, coinciding with the decompilation project reaching completion.
In January 2022, a group of community developers named Harbour Masters released footage and screenshots of Ocarina of Time running natively on Microsoft Windows, in a widescreen aspect ratio not supported by the original Nintendo 64 release. The project was titled "Ship of Harkinian", a reference to Zelda: Wand of Gamelon. Speaking to Video Games Chronicle, Kenix, now part of Harbour Masters, estimated the project was "approximately 90%" complete.
Prior to Ship of Harkinian's release, Harbour Masters showcased various experimental game modifications to Ocarina of Time, such as gyroscopic aiming and 4K texture support.
Ship of Harkinian launched for Windows in March 2022.
Additional platform support and features
In May 2022, Harbour Masters announced the release of a Linux port of Ship of Harkinian via "Ship of Harkinian Direct", an online video parody presentation of Nintendo Direct. Additional features noted in this Direct include save states, an integrated cheat menu, accessibility options, and support for running the game at 60 frames per second.
Two months later, in July 2022, an additional Ship of Harkinian Direct was released, announcing the release of Ship of Harkinian for macOS and Wii U. Additional features promoted in this Direct include a graphic interface for rebinding controls, a "randomizer" which randomizes various elements of the game to enhance replayability, and the ability to set an arbitrary framerate (up to 250FPS).
Ship of Harkinian received Nintendo Switch support in the September 2022 "Zhora Alfa" update.
In April 2023, a new Ship of Harkinian Direct was released, announcing custom texture and model support. Multiplayer functionality was added to the port; a second player can take control of Ivan the Fairy, described as a fairy "who likes to play tricks", whose abilities can either help or hinder the main player.
Other releases
Harbour Masters have expressed intent to create a source port for The Legend of Zelda: Majora's Mask shortly after ZRET completes their decompilation of the game.
In November 2023, Harbour Masters revealed that they had fully decompiled Majora's Mask, and are currently working on a PC port provisionally called 2Ship2Harkinian, with its first version being released on 26 May 2024.
In December 2024, Harbour Masters released the first version of StarShip, a PC port of Star Fox 64.
Reception
Reception to Ship of Harkinian has been generally positive.
Ship of Harkinian has been favorably compared against the Nintendo Switch Online version of Ocarina of Time. Nick Rodriguez of Screen Rant deemed Ship of Harkinian "significantly better than the current Switch version in almost every regard", with The Verge's Derek Hill expressing similar sentiment: "As long as Nintendo is content putting out alarmingly low-quality versions of their classic games for shockingly high prices, Ship of Harkinian is proof that the unofficial option is sometimes the best option."
Some outlets expressed apprehension over Ship of Harkinian, fearing that Nintendo's perceived litigiousness could jeopardize the project. In discussing Ship of Harkinian's long-term prospects, GameSpot writer Jenny Zheng remarked that that Ship of Harkinian's "odds aren't great", while characterizing Nintendo as "notoriously copyright-lawsuit-happy". Luke Plunkett of Kotaku referred to Ship of Harkinian's legality as "murky", but noted that other projects built off of reverse engineering efforts were still active as of writing. In a statement to GamesRadar+, Harbour Masters contributor Kenix defended the legality of Ship of Harkinian: "The [Ocarina of Time] assets will be ripped from a user's own ROM that they must provide and then be exported into an archive compatible with the Ship of Harkinian. None of Nintendo's own property is involved in the process." Harbour Masters encouraged users to support official releases of Ocarina of Time, and offered a unique role on their Discord server to those who can provide proof of ownership.
References
2022 video games
The Legend of Zelda video games
Linux games
MacOS games
Nintendo fan games
Open-world video games
Reverse engineering
Single-player video games
Unauthorized video games
Video games with time manipulation
Windows games | Ship of Harkinian | [
"Engineering"
] | 1,327 | [
"Reverse engineering"
] |
74,751,551 | https://en.wikipedia.org/wiki/CoRoT-26b | CoRoT-26b is a gas giant exoplanet that orbits a G-type star, CoRoT-26. It has a mass of 0.52 Jupiters, takes 4.2 days to complete one orbit of its star, and is 0.0526 AU from its star. Its discovery was announced in 2013.
References
Exoplanets discovered in 2013
Exoplanets discovered by CoRoT
Transiting exoplanets
Ophiuchus | CoRoT-26b | [
"Astronomy"
] | 96 | [
"Ophiuchus",
"Constellations"
] |
74,752,544 | https://en.wikipedia.org/wiki/Jonathan%20Jeffers | Jonathan Jeffers is a mechanical engineer and Professor of Mechanical Engineering at Imperial College London. He was awarded a Research Professorship by the National Institute for Health and Care Research (NIHR), the first engineer to receive this award. His research focuses on improving surgical treatment of osteoarthritis.
Early life and education
Jonathan Jeffers studied Mechanical Engineering at Trinity College Dublin. He also has a PhD from the University of Southampton.
Career and research
His research focuses on topics such as orthopedic implants, external stabilisers for broken bones and biomechanics in hip surgery. He is also a co-investigator at the Smart Materials Hub of the UK Regenerative Medicine Platform. During the COVID-19 pandemic he worked on 3D printing FFP3 face masks through injection moulding.
He was awarded an NIHR Research Professorship in 2019 for his research on improving treatment options for osteoarthritis after early intervention orthopaedic surgery.
Jeffers is the Chief Technology Officer of OSSTEC, a company that manufactures orthopaedic implants using 3D printing. He was a co-founder of Additive Instruments, which was acquired by Smith&Nephew in 2023.
References
Living people
NIHR Research Professors
Mechanical engineers
Alumni of Trinity College Dublin
Alumni of the University of Southampton
Biomedical engineers
Academics of Imperial College London
Year of birth missing (living people) | Jonathan Jeffers | [
"Engineering"
] | 284 | [
"Mechanical engineers",
"Mechanical engineering"
] |
74,752,908 | https://en.wikipedia.org/wiki/TOI-1431%20b | TOI-1431 b, also known as MASCARA-5b, is an ultra-hot Jupiter exoplanet orbiting TOI-1431 in the constellation of Cepheus. It has an orbital period of 2.7 days. Its dayside temperature is 2,700 K (2,427 °C), making it hotter than 40% of stars in our galaxy. The nightside temperature is 2,600 K (2,300 °C).
References
Cepheus (constellation)
Exoplanets discovered in 2021
Transiting exoplanets
Exoplanets discovered by TESS
Exoplanets discovered by MASCARA | TOI-1431 b | [
"Astronomy"
] | 129 | [
"Constellations",
"Cepheus (constellation)"
] |
74,753,162 | https://en.wikipedia.org/wiki/Manganese%28III%29%20phosphate | Manganese(III) phosphate is an inorganic chemical compound of manganese with the formula MnPO4. It is a hygroscopic purple solid that absorbs moisture to form the pale-green monohydrate, though the anhydrous and monohydrate forms are typically each synthesized by separate methods.
Production and properties
Manganese phosphate monohydrate is produced by the reaction of an Mn(II) salt, such as manganese(II) sulfate, and phosphoric acid, followed by oxidation by nitric acid. Another method of producing the monohydrate is by the comproportionation of permanganate and Mn(II) in phosphoric acid:
MnO4– + 4 Mn2+ + 10 PO43– + 8 H+ → 5 [Mn(PO4)2]3– + 4 H2O
The diphosphomanganate(III) ion slowly converts to the monohydrate. Heating of the monohydrate does not yield the anhydrous form, instead, it decomposes to manganese(II) pyrophosphate (Mn2P2O7) at 420 °C:
4 MnPO4·H2O → 2 Mn2P2O7 + 4 H2O + O2
To produce the anhydrous form, lithium manganese(II) phosphate is oxidized with nitronium tetrafluoroborate under inert conditions.
The anhydrous form is sensitive to moisture. In the absence of moisture, it decomposes at 400 °C, but when moisture is present, it slowly transitions to an amorphous phase and decomposes at 250 °C.
Structure and natural occurrence
The anhydrous form has an olivine structure and naturally occurs as the mineral purpurite. The monohydrate has a monoclinic structure, similar to that of magnesium sulfate monohydrate, but has distortions at the octahederal manganese center due to the Jahn-Teller effect. It naturally occurs as the mineral serrabrancaite.
The monohydrate form has cell parameters of a = 6.912 Å, b = 7.470 Å, β = 112.3°, and Z = 4. It consists of interconnected distorted trans-[Mn(PO4)4(H2O)2] octahederons.
References
Manganese(III) compounds
Phosphates | Manganese(III) phosphate | [
"Chemistry"
] | 515 | [
"Phosphates",
"Salts"
] |
74,753,770 | https://en.wikipedia.org/wiki/Menstruation%20and%20mental%20health | Menstruation can have a notable impact on mental health, with some individuals experiencing mood disturbances and psychopathological symptoms during their menstrual cycle. Menstruation involves hormonal fluctuations and physiological changes in the body, which can affect a person's mood and psychological state. Many individuals report experiencing mood swings, irritability, anxiety, and even depression in the days leading up to their menstrual period. This cluster of symptoms is often referred to as premenstrual syndrome (PMS). For some individuals, the psychopathological symptoms associated with menstruation can be severe and debilitating, leading to a condition known as premenstrual dysphoric disorder (PMDD). PMDD is characterized by intense mood disturbances, cognitive, and somatic symptoms, which occur in a cyclical pattern linked to the menstrual cycle. In addition to PMDD, menstruation can exacerbate existing mental health conditions. The complex relationship between menstruation and mental well-being has garnered increased attention in both scientific research and public discourse.
Premenstrual disturbances
The period before menstruation, known as the premenstrual phase, is often linked to emotional distress. Conditions related to the menstrual cycle encompass premenstrual tension syndrome, premenstrual dysphoric disorder, and the exacerbation of another medical condition during the premenstrual phase.
Menstruation is linked to a range of psychopathological symptoms, such as lower self-esteem, increased anxiety, dysphoria, and feelings of being persecuted. Changes in behavior, like decreased social interaction during menstruation, can lead to feelings of loneliness and potentially contribute to the development of depression. Several reviews have reported that psychopathological symptoms and mental disorders, such as psychoses, suicidal tendencies, post-traumatic stress disorder, and addictive behaviors, tend to worsen during menstruation. Variations in ovarian hormone levels are also linked to the presence of symptoms related to eating disorders. Some comprehensive studies have indicated that women might be at a higher risk of suicide during menstruation. The symptoms occurring during menstruation can have a significant impact on mental health and lead to severe consequences.
Premenstrual tension syndrome
Premenstrual tension syndrome is a condition marked by particular metabolic, environmental, or behavioral factors that arise during the luteal phase of the menstrual cycle. It results in recurring somatic, behavioral, or affective symptoms that disrupt a person's daily life. While the quality of studies and their findings in this area can vary, it's common for women to report symptoms like mood swings, depression, tension, irritability, and anger occurring before their period.
Premenstrual dysphoric disorder
Premenstrual dysphoric disorder is an affective disorder characterized by emotional, cognitive, and somatic symptoms that consistently occur in the days leading up to menstruation and improve shortly after it begins. These somatic symptoms encompass joint pain, overeating, and lethargy, while cognitive symptoms involve forgetfulness and difficulty concentrating. Mood-related symptoms consist of irritability and depression. Studies evaluating the use of combined oral contraceptive pills containing both progesterone and estrogen have demonstrated their effectiveness in alleviating the symptoms of premenstrual dysphoric disorder.
Comorbidity
Psychotic symptoms tend to worsen when estrogen levels drop during the premenstrual period, leading to increased psychiatric admissions for women with schizophrenia just before and during their menstrual cycles. Another contributing factor to the higher incidence of schizophrenia onset in midlife women may be the reduced estrogen levels associated with menopause. In women with bipolar disorder, especially bipolar II disorder, premenstrual syndrome and premenstrual dysphoric disorder are common. For those women who experience these premenstrual conditions, bipolar affective symptoms and mood swings may be more severe.
Menstrual psychosis
Menstrual psychosis was documented in the mid-19th century and has been extensively discussed in numerous articles. However, it is not widely recognized or diagnosed by modern psychiatrists. The earliest clear clinical descriptions of this condition emerged in French literature around 1850, with most well-documented cases appearing in German literature between 1880 and 1930. As per British psychiatrist Ian Brockington, diagnosing menstrual psychosis requires specific criteria to be met, including symptoms recurring in sync with the menstrual cycle, acute onset against a background of normality, a brief duration followed by complete recovery, and the presence of psychotic features such as delusions, hallucinations, confusion, mutism, stupor, or manic syndrome.
See also
Miscarriage and mental disorders
Psychiatric disorders of childbirth
References
Menstrual cycle
Mental disorders
Women's mental health | Menstruation and mental health | [
"Biology"
] | 1,013 | [
"Mental disorders",
"Behavior",
"Human behavior"
] |
74,753,942 | https://en.wikipedia.org/wiki/Kappa%20Doradus | Kappa Doradus, Latinized from κ Doradus, is a solitary star located in the southern constellation Dorado. It is faintly visible to the naked eye as a white-hued point of light with an apparent magnitude of 5.28. The object is located relatively close at a distance of 220 light-years based on Gaia DR3 parallax measurements and its distance from the Solar System is not changing, having a somewhat constrained heliocentric radial velocity of . At its current distance, Kappa Doradus' brightness is diminished by two-tenths of a magnitude due to interstellar extinction and it has an absolute magnitude of +1.15.
The object has been given many different classes. Houk & Cowley (1975) gave a class of A8/9 III/IV, indicating that it is an evolved A-type star with the characteristics of an A8 and A9 star and the blended luminosity class of a giant star and a subgiant. It has also been given a class of A8 IV and A5 III, indicating either a slightly evolved subgiant or an evolved giant star. Kappa Doradus has 1.78 times the mass of the Sun and 2.88 times the radius of the Sun. However, this is only its polar radius, as it has an equatorial bulge 26% greater than its polar radius. It radiates 26.6 times the luminosity of the Sun from its photosphere at an effective temperature of . Kappa Doradus is metal deficient with an iron abundance 66.1% of the Sun's or [Fe/H] = −0.18. Like many hot stars it spins rapidly, having a projected rotational velocity of , which causes the aforementioned oblation.
Kappa Doradus variability was first observed in 1981 by astronomer H. M. Matizen. In the paper, it is used as a comparison star for Alpha Doradus. Matizen found out that Kappa Doradus show Delta Scuti-like amplitudes of 0.03 magnitudes in the visual passband within hours. As of 2004 however, it has not been confirmed to be variable.
References
A-type subgiants
Suspected variables
Dorado
Doradus, Kappa
Doradus, 12
PD-59 00376
030478
022040
1530
220414802 | Kappa Doradus | [
"Astronomy"
] | 477 | [
"Dorado",
"Constellations"
] |
74,753,947 | https://en.wikipedia.org/wiki/The%20Politics%20of%20Modelling%2C%20Numbers%20Between%20Science%20and%20Policy | The Politics of Modelling, Numbers Between Science and Policy is a multi-authors book edited by Andrea Saltelli and Monica Di Fiore and published in August 2023 by Oxford University Press.
Synopsis
The Politics of Modelling elaborates and expands on themes of responsible modelling from a manifesto published in the journal Nature in 2020. The text is structured into three main sections: Meeting Models, The Rules, and The Rules in Practice. The combination of theory with policy relevant examples makes the book accessible to modellers, researchers of modelling, and policy makers.
The volume comes with a foreword of Wendy Nelson Espeland and a preface of Daniel Sarewitz, with chapters from Andy Stirling, Wolfgang Drechsler, Philip B. Stark, Ting Xu, Paolo Vineis, Andrea Saltelli, and other scholars.
Reception
The book argues that models live in a “state of exception” provided by their access to a wealth of methodology of analysis, and by their epistemic authority borrowed from mathematics. This state allows models to better defend an appearance of neutrality that is appreciated by policymakers in search of a justification. A review published in the Science notes that the volume incorporated insights from science and technology studies to explore modeling beyond its technical aspects A second review in the Minerva notes the book’s reference to the works of historians Margaret Morrison and Mary S. Morgan in considering models as mediators whereby models are simultaneously a tool, an interpretation, and a representation of the system.
The book contrasts the danger of cynicism with suggestions to make models serve society, based on theory, examples, and a call for participatory modelling linked to Post-normal science, sensitivity auditing and the concept of extended peer community. Reviewers also noted that the book ignores other ongoing efforts in enhancing or formalizing modelling practices such as the framework proposed van Voorn, and the Good Modelling Practice handbook developed for water management purposes in the Netherlands. Reviewers pointed to the book's failure to cover the ‘fit-for purpose’ movement in modelling. Other points where the book was found to be lacking by critics were the challenge of participatory modelling, related to gaming and power relations such as Arnsteinds’ ladder of participation.
A review in Mathematics Magazine notes the book’s attention to sensitivity analysis: "[The authors] stress the importance of sensitivity analysis, with a highly-illustrative and illuminating example that analyzes the EOQ (economic order quantity) formula."
References
Links
Saltelli, A. and Di Fiore, M. (eds) (2023) The politics of modelling. Numbers between science and policy. Oxford: Oxford University Press, at OUP website.
Chapters available in open access.
Models: a state of exception, Oxford Martin School, November 20 2023, Launch of The Politics of Modelling – video.
Podcast – interview for ABC NET RADIO, AUS August 26, 2023: Assumptions and consequences: the politics of modelling, Guests: Ehsan Nabavi and Andrea Saltelli, Producer – Chris Bullock.
See also
Sociology of quantification
Ethics of quantification
Sensitivity analysis
Sensitivity auditing
Related readings
Desrosières, Alain. (1998). The Politics of Large Numbers: a history of statistical reasoning, Harvard University Press.
Scoones, I., & Stirling, A. (2020). The Politics of Uncertainty. (I. Scoones & A. Stirling, Eds.), Abingdon, Oxon; New York, NY: Routledge, 2020. Series: Pathways to sustainability: Routledge. doi:10.4324/9781003023845
Mennicken, A., & Salais, R. (Eds.). (2022b). The New Politics of Numbers: Utopia, Evidence and Democracy, Palgrave Macmillan.
Mathematical modeling
Mathematical terminology
Mathematical and quantitative methods (economics) | The Politics of Modelling, Numbers Between Science and Policy | [
"Mathematics"
] | 779 | [
"Applied mathematics",
"Mathematical modeling",
"nan"
] |
74,753,958 | https://en.wikipedia.org/wiki/Myocarditis-myositis-myasthenia%20gravis%20overlap%20syndrome | Myocarditis-myositis-myasthenia gravis overlap syndrome (IM3OS) is a rare immune-related adverse event primarily associated with the use of immune checkpoint inhibitors (ICIs). These ICIs, which have been incorporated into the treatment of various malignancies, function by activating the immune system to detect and attack cancer cells. However, a side effect can involve the immune system inadvertently attacking normal tissues and organs.
Clinical presentation
The most commonly reported symptoms in patients with IM3OS include fatigue and muscle weakness. Other symptoms can be specific to the organs affected, such as cardiac arrhythmias and depressed ejection fraction in cases where the heart is involved.
Diagnosis and management
A high index of clinical suspicion is necessary for diagnosis. Prompt comprehensive investigations are required to ascertain the presence of IM3OS, especially in patients who have recently received ICIs. The median number of ICI doses before the onset of IM3OS symptoms has been reported to be one. Immediate initiation of immunosuppressive therapy and supportive therapies, such as high-dose steroids, is paramount upon suspicion or diagnosis of IM3OS. Early multidisciplinary team involvement is also essential.
Prognosis
IM3OS is associated with significant mortality and morbidity. In a systematic review, 60% of patients diagnosed with IM3OS succumbed to acute complications in the hospital.
References
Syndromes
Oncology
Immunology | Myocarditis-myositis-myasthenia gravis overlap syndrome | [
"Biology"
] | 300 | [
"Immunology"
] |
74,754,012 | https://en.wikipedia.org/wiki/Simulation%20decomposition | SimDec, or Simulation decomposition, is a hybrid uncertainty and sensitivity analysis method, for visually examining the relationships between the output and input variables of a computational model.
SimDec maps multivariable scenarios onto the distribution of the model output. This visual analytics approach exposes the underlying nature of the model behavior, including its nonlinear and multivariate interaction effects.
SimDec can be used in any range of science, engineering, and social domains. Existing applications include business and environmental issues.
Method
SimDec operates on Monte Carlo simulation (or measured) data where both output and input values are recorded. At least one thousand observations (or simulated iterations) are typically recommended to preserve the readability of the resulting histograms. An outline of the decomposition algorithm, which is readily available in multiple programming languages, proceeds as follows:
Select the input variables for decomposition. One can use sensitivity indices (see variance-based sensitivity analysis) to define the most influential variables for decomposition or choose them manually according to the decision-problem context (for example, only those input variables that the decision-maker can act upon). Two to three input variables, ordered by decreasing value of their sensitivity indices, usually provide the most meaningful decomposition results.
Divide the inputs into states. The numeric ranges of the inputs are split into several intervals with an equal number of observations in each. For categorical variables, the categories represent states.
Form scenarios. All combinations of states of the selected input variables produce unique scenarios or subsets of the data. For example, if the range of X2 is divided into low, medium and high, and X3 takes values of 1 or 2, six scenarios are formed:
(i) X2 low & X3 = 1,
(ii) X2 low & X3 = 2,
(iii) X2 medium & X3 = 1,
(iv) X2 medium & X3 = 2,
(v) X2 high & X3 = 1, and
(vi) X2 high & X3 = 2.
Assign scenarios to each output value. The simulation data is used to define the scenario index for each simulation run. For example, if an X2 value falls into the low state and X3 is equal to 2, the corresponding scenario, defined in Step 3, is (ii).
Color-code the output distribution. When all output values are assigned scenario indices, they are plotted as series in a stacked histogram, visually separated by color-coding. For ease of visual perception, the states of the most influential input variable are assigned distinct colors, and all the remaining partitions take shades of those colors (see Figure).
All of these steps can be run automatically on the given data using the open-source SimDec packages currently available in Python, R, Julia, and Matlab. A SimDec template in Excel runs a Monte Carlo simulation of a spreadsheet model but possesses only a manual option for input selection.
How to read SimDec
Histogram
Histogram is an approximate representation of the distribution of numerical data. Its horizontal axis shows the range of the variable of interest, and its vertical axis denotes count, also called frequency, or, if divided by the total number of data points, probability.
The distribution alone can supply only limited information about the data – its minimum, maximum, and shape (where the most of data occurs).
Judging the importance of inputs
If an input variable has no effect on the output, its states (e.g., low & high) would lie on top of each other on the SimDec histogram, occupying fully overlapping ranges of the output. If an input variable has a strong effect and explains most of the variance of the output, the border between its states on the SimDec histogram would be vertical. Such visualization has an important decision-making implication – e.g., if the high state of X can be achieved, it would guarantee a certain range of Y. All cases in-between with low-to-strong effects would show a diagonal border between the states. The less they overlap, the larger the effect of X on Y.
While the horizontal displacement of sub-distributions on the SimDec histogram is the key to interpreting the results, the vertical disposition of sub-distributions is just a technical matter of the order of plotting the series of the stacked histogram.
Exploring the interaction of inputs
When two or more input variables are used for decomposition, it becomes possible to examine their joint effects. A schematic visualization portrays how different types of joint effects of input variables on the output appear on SimDec visualization.
Understanding the nature of interaction effects in a computational model and its behavior in general is crucial for effective decision-making.
Limitations
The SimDec method has several limitations:
It is based on Monte Carlo simulation and thus requires running a computational model a thousand of times or more. To models that take hours to evaluate once, it would be impossible to use SimDec (unless a supercomputer and/or large of time are available).
SimDec is based on a histogram, thus, for binary or categorical output variables, the visualization would be very limited (e.g., only a few bins).
The more input variables one selects for the decomposition, the less readable the histogram becomes. Only cases with two and three input variables are presented in.
References
See also
Sensitivity analysis
Data and information visualization
Histogram
Interaction (statistics)
Uncertainty
Decision making
Knowledge representation
Mathematical modeling
Mathematical and quantitative methods (economics) | Simulation decomposition | [
"Mathematics"
] | 1,145 | [
"Applied mathematics",
"Mathematical modeling"
] |
74,756,339 | https://en.wikipedia.org/wiki/Optical%20glass | Optical glass refers to a quality of glass suitable for the manufacture of optical systems such as optical lenses, prisms or mirrors. Unlike window glass or crystal, whose formula is adapted to the desired aesthetic effect, optical glass contains additives designed to modify certain optical or mechanical properties of the glass: refractive index, dispersion, transmittance, thermal expansion and other parameters. Lenses produced for optical applications use a wide variety of materials, from silica and conventional borosilicates to elements such as germanium and fluorite, some of which are essential for glass transparency in areas other than the visible spectrum.
Various elements can be used to form glass, including silicon, boron, phosphorus, germanium and arsenic, mostly in oxide form, but also in the form of selenides, sulfides, fluorides and more. These materials give glass its characteristic non-crystalline structure. The addition of materials such as alkali metals, alkaline-earth metals or rare earths can change the physico-chemical properties of the whole to give the glass the qualities suited to its function. Some optical glasses use up to twenty different chemical components to obtain the desired optical properties.
In addition to optical and mechanical parameters, optical glasses are characterized by their purity and quality, which are essential for their use in precision instruments. Defects are quantified and classified according to international standards: bubbles, inclusions, scratches, index defects, coloring, etc.
History
The earliest known optical lenses, dating from before 700 BC, were produced under the Assyrian Empire: they were made of polished crystals, usually quartz, rather than glass.
It wasn't until the rise of the Greeks and Romans that glass was used as an optical material. They used it in the form of spheres filled with water to make lenses for lighting fires (burning glass), as described by Aristophanes and Pliny, or to make very small, indistinct characters larger and sharper (magnifying glass), according to Seneca.
Although the exact date of their invention is not known, glasses are said to have been described in 1299 by Sandro di Popozo in his Treatise on Family Conduct: "I am so altered by age, that without these lenses called spectacles, I would no longer be able to read or write. They have recently been invented for the benefit of poor old people whose eyesight has become bad". At the time, however, "glasses" were actually made from beryl or quartz.
The only lens available at the time, ordinary soda-lime glass, was unable to compensate for optical aberrations. However, it evolved slowly over the centuries. It was first lightened by the use of ashes, which contain manganese dioxide that transforms ferrous oxide (FeO) into ferric oxide (Fe2O3), which is much less colorful. Then, around 1450, Angelo Barovier invented "crystalline glass" (vetro cristallino) or "Venetian glass" (cristallo di Venezia), improving on the previous process by purifying the ashes by leaching to obtain a purer potash. Lime was introduced, first for economic reasons in the 14th century, then as a technical improvement in Bohemia in the 17th century (Bohemian glass), eliminating a very large proportion of impurities. This practice did not arrive in France until the middle of the eighteenth century. It was at this time that the Manufacture Royale de Glaces de Miroirs (Compagnie de Saint-Gobain S.A.) began to produce glass composed of 74% silica, 17.5% soda and potash, and 8.5% lime.
Thus, the first complex optical instruments, such as Galileo's telescope (1609), used ordinary soda-lime glass (the first crown glass), composed of sand, soda, potash and sometimes lime, which, although suitable for glazing or bottles, was hardly suitable for optical applications (distortion, blurred effect, irregularities, etc.). In 1674, the British inventor George Ravenscroft, wishing to rival Venetian and Bohemian crystal while being less dependent on imported raw materials, replaced lime with lead(II) oxide to compensate for glass's lack of resistance to humidity, thus inventing lead crystal (the first flint glass, named after the high-purity English siliceous stone used), brighter than ordinary glass, composed of silica, lead oxide and potash.
Chester Moore Hall (1703-1771), using the two types of glass available (soda-lime crown and lead flint), invented the first achromatic doublet. His work was taken up by John Dollond in his Account of some experiments concerning the different refrangibility of light, published in 1758.
The real revolution in optical glass came with the development of industrial chemistry, which facilitated the composition of glass, allowing properties such as refractive index and dispersion coefficient to be varied. Between 1880 and 1886, the German chemist Otto Schott, in collaboration with Ernst Abbe, invented new glasses containing oxides such as "anhydrous baryte" (barium oxide BaO) and anhydrous boric acid (B2O3), with which he developed barium crowns, barium flints and borosilicate crowns.
Between 1934 and 1956, other oxides were used. Then, by adding phosphates and fluorides, phosphate crowns and fluorine crowns were obtained. As optics became increasingly complex and diverse, manufacturers' catalogs expanded to include 100 to 200 different lenses; glass melts increasingly included special components such as oxides of heavy elements (high refractive index and low dispersion), chalcogenides (sulfide, selenide, telluride), halides such as fluorides (low refractive index and high dispersion) or phosphides, cerium-doped glasses to obtain radiation-resistant lenses, and so on.
Since the 1980s, however, glass catalogs have tended to become increasingly limited.
Properties
The most important physical properties of glass for optical applications are refractive index and constringency, which are decisive in the design of optical systems, and transmission, glass strength and non-linear effects.
Index and constringency
The refractive index indicates the refractive power of a glass, i.e. its ability to deflect light rays to a greater or lesser extent. This deflection can be deduced from Descartes' law. The refractive index is a wavelength-dependent quantity, creating chromatic aberrations in a system by refracting rays more or less according to their wavelength: This is the phenomenon observed when light is decomposed by a prism. Several laws have approximated this relationship to wavelength, notably Cauchy's law and Sellmeier equation.
The refractive index of a glass is given for the yellow line known as the d line of helium (then noted nd) or for the green e line of mercury (then noted ne), depending on usage and the two main standards used.
The dependence of refractive index on wavelength requires a measure of the glass's dispersion, i.e. the difference in deviation between two wavelengths. A highly dispersive glass will deflect short wavelengths to a great extent, but long wavelengths to a lesser extent. The measure of dispersion is the Abbe number, or constringence. The main dispersion is the difference nF-nC (helium lines) or nF'-nC' (cadmium lines), and constringencies for the same lines as the refractive index are deduced by and . A high Abbe number means that the glass is not very dispersive, and vice versa.
Lenses are usually divided into two groups with the generic names of crown and flint, referring respectively to low-dispersion, low-index lenses and high-dispersion, high-index lenses. Typically, the distinction is made at around νd=50: lenses below this value are flints, the others are crowns.
These two parameters alone are needed to differentiate between lenses: two lenses with equal nd and νd are identical. Glasses are represented on the so-called Abbe diagram, a graph with abscissa nd and ordinate νd, where each glass is denoted by a point on the graph.
Oxide glasses fall into a range of nd from 1.4 to 2.0 and νd from 20 to 90, with SiO2 being the oxide glass with the highest contringency and lowest index. Fluoride glasses can go up to νd>100 and nd<1.4, BeF2 being the fluoride glass at the highest constringency and lowest index. Chalcogenide glasses have indexes exceeding 2, a large proportion of which cannot be shown on an Abbe diagram due to their absorption in visible wavelengths preventing a relevant νd measurement. For optical materials that are opaque in the visible range, constringence is measured at longer wavelengths.
This classification also has its limitations when it comes to active optical glasses (birefringence, acousto-optic effect, and non-linear effects), optical filters or graded-index lenses, so we restrict the term "classical optical glass" to the aforementioned glasses, i.e. those with limited index and dispersion, which can be described essentially by their dispersive behavior and refractive index.
Transmission and absorption
Another very important characteristic of optical glass is its absorption and transmission behaviour. The use to which the future lens will be put determines its behavior: filters that absorb in certain spectral bands, lenses that are highly transparent in the visible, ultraviolet or infrared, resistance to radiation.
As a general rule, the transmittance of the glass is given by the manufacturer, noted τi or Ti, a value that depends on the thickness of the material and whose measurement makes it possible to take into account the loss of transmission due to absorption and diffusion by internal defects in the glass. Since the transmittance term takes into account the refractive index via the Fresnel coefficient, it is also dependent on the wavelength and thickness of the sample via the formula where is the transmittance and thickness.
Transmittance windows are of particular interest when it comes to choosing the right glass for applications such as far-infrared or far-ultraviolet. These windows are the result of the absorption of the materials making up the glass, which increases in the infrared and ultraviolet. Absorption in these two wavelength ranges is due to distinct phenomena, and can evolve differently depending on environmental conditions.
Ultraviolet absorption
In the ultraviolet, or UV, the drop in transmission is due to the electronic transitions of the elements making up the glass: valence electrons absorb wavelengths whose energy corresponds to their band gap. According to solid-state band theory, electrons can only take on certain specific energy values in particular energy levels, but with sufficient energy, an electron can move from one of these levels to another. Light waves are charged with an energy hν, inversely proportional to wavelength (ν=c/λ), which can enable an electron to pass from one level to another if this energy is sufficient and therefore if the wavelength is short enough. A silica glass absorbs wavelengths below 160 nm, a glass based on boron trioxide (B2O3) absorbs below 172 nm, a phosphorus pentoxide glass (P2O5) absorbs below 145 nm.
There are two types of oxygen in oxide glasses: bridging and non-bridging (possessing an excess electron charge), detectable by photoelectron spectroscopy. Non-bridging oxygen possesses electrons whose kinetic energy after release by monochromatic X-rays is higher than that of bridging oxygen. Bonds between non-bridging oxygens and cations are generally ionic. These characteristics give the glass its energetic band properties, making it more or less effective at transmitting radiation. Depending on the intensity of the bonds with the cations in the glass, the transmission window varies: in the presence of alkali metals, electrons can move from one band to the other more easily, as they are less bound to the non-bridging oxygens. On the other hand, the introduction of aluminium (Al2O3) to replace silica will increase the glass's transmission window, as the tetrahedral configuration of alumina reduces the proportion of non-contacting oxygens and therefore of electrons able to move from the valence band to the conduction band.
As a result, glasses containing heavy metals (such as Ti+ or Pb2+) tend to transmit less well than others, since the oxygen will tend to share its electrons with the cation and thus reduce the band gap. The disadvantage is that the addition of these metals results in higher refractive indices. Depending on the heavy metal used, the drop in UV transmission will be more or less rapid, so lead lenses transmit better than niobium or titanium lenses. Attention to crucible and furnace materials is therefore very important, as these can also influence the UV transmission window. Platinum, for example, is widely used in glass melting, but inclusions of platinum particles in the glass paste can cause undesirable transmission losses due to impurities.
Another source of variation in UV transmission loss is ambient temperature: the higher the temperature of the glass, the more the UV drop will shift towards longer wavelengths, due to the material's reduced band gap.
Solarization, which is the exposure of glass (or paint, for that matter) to electromagnetic radiation, can "yellow" glass depending on the wavelength and intensity of the radiation. Lenses with the best UV transmission are the most affected by solarization, which modifies their transmission window. Lenses can be doped with cerium dioxide (CeO2), which shifts the transmission drop to longer wavelengths and stabilizes it. This doping is one of the processes used to create anti-radiation glasses, since a glass doped in this way has the particular ability to protect against the most energetic types of radiation, such as X-rays and gamma rays.
Infrared absorption
In infrared, or IR, the physical phenomena leading to a drop in transmission are different. When a molecule receives a given amount of energy, it begins to vibrate in different modes: fundamental, first harmonic, second harmonic, etc., corresponding to periodic movements of the atoms in the molecule; each frequency associated with the energy of the molecule's vibration mode is absorbed.
In silica glass, the Si-O bond has two main modes of vibration, rotation and elongation. Since the frequency of elongation is 0.34 × 1014 Hz, absorption will take place at 8.8 μm (fundamental), 4.4 μm (harmonic 1), 2.9 μm (harmonic 2), etc. As the absorption due to this vibration is very strong, silica becomes opaque from the first harmonic onwards. Most quartz glasses even show a marked drop in transmission at harmonic 2.
Chalcogenide glasses are used to reduce the frequency of molecular vibrations: as sulfur or selenium are heavier, their vibration modes are weaker, and their transmission is, therefore, better in the infrared. However, this comes at the price of visible transmission, since chalcogenide glasses are opaque in the visible. Another solution is to produce halide glasses, in particular fluoride glasses. As fluorine is highly electronegative, the bonds between anions and cations are weakened, and vibrations are therefore weaker.
Glass humidity, i.e. the presence of water in the material, has a strong influence on the transmission curve of glasses in the 2.9 μm to 4.2 μm region. Water takes the form of OH− groups, whose O-H bond vibrates at a frequency of around 90 THz, equivalent to an absorption of wavelengths from 2.9 μm to 3.6 μm. The higher the humidity of the sample, the greater the local drop in transmission, with very high humidity even causing absorption at the harmonics of the O-H bond vibration, at around 200 nm.
Emission and non-linear phenomena
Lasers are often used at very high illuminance levels. It has been found that in this high illumination range, the refractive index follows a law that deviates from the linear domain and becomes proportional to the intensity of the luminous flux: where is the refractive index of the material, the wavelength, the intensity of the light beam, the refractive index for low powers. For silica, for example, is 3.2 × 10–20 m2 W−1 for =1,060 nm. The most dispersive glasses tend to have the highest non-linear refractive indices, probably due to the metal ions present in the glass.
Above TW mm−2, the fluence (or flux) is sufficient to create higher-order non-linear optical phenomena such as multiphonon absorption and avalanche photo-ionization. The first phenomenon makes the material absorbent through the addition of two photons, which release an electron. The second phenomenon is the acceleration of an electron released by the electromagnetic field, the electron's kinetic energy being transmitted to other neighboring electrons. These two combined effects can cause damage to glass by destroying the vitreous lattice (freed electrons give energy to other electrons which are more easily freed, and the lattice bonds are weakened by electron depletion). The material may be vaporized at sufficient speed that the phonons cannot transmit the energy in the form of heat to the rest of the glass.
In 1988, an experiment showed that silica, whose lattice is isotropic, is capable of emitting green radiation when crossed by powerful infrared radiation. The generation of a second harmonic in this setting is atypical, but could be explained by the presence of F-center.
Fluorescence can appear in optical glasses. Fluorescence is the re-emission of higher-wavelength radiation from an illuminated material. The energy of the incident light excites the material's electrons, which then de-excite and return to their ground state, emitting a photon with a longer wavelength than the original one. This phenomenon is particularly troublesome in applications where the presence of stray light or light of a different wavelength from the reference wavelength poses a problem. In lasers, for example, it's important to agree on a single, precise spectral line. Causes of fluorescence include rare-earth ions, impurities and color centers.
Fabrication
The basic materials used to manufacture optical lenses must be particularly pure, as any inclusion or impurity could not only degrade performance but also cause considerable damage to the lens (breakage, darkening, tinting, etc.). For example, the sand used to manufacture silica-based glass must contain an extremely low proportion of ferric oxide (Fe2O3) (10 ppm maximum) and even lower proportions of other oxides and elements (cobalt, copper, nickel, etc.). There are very few geographical sites where the sands are sufficiently pure for these applications.
Most glass is melted in a pot furnace, which is used to melt limited quantities of glass, while certain mass-produced optical glasses (such as borosilicate glass) are melted in tank furnaces for continuous glass production.
The glassmaking process comprises a number of stages, beginning with the melting of the glass paste, followed by refining and then tempering or annealing, which are two different finishes. Finally, if required, the glass can be polished, particularly in the case of mirrors and lenses, for any application where the objective is high image quality.
The materials are placed together in the furnace and gradually heated to their melting point. Chemical reactions of composition or decomposition of molecules take place, resulting in significant off-gassing during this phase. Hydrates, carbonates, nitrates and sulfates recompose to form the glass paste with the vitrifying elements, giving rise to gases such as water vapor, carbon dioxide, sulfur dioxide and others. For example, 1 L of soda-lime glass paste releases around 1,440 L of various gases when heated to 100 °C, of which 70% is carbon dioxide.
Refining is an essential stage in the quality of optical lenses, since it involves homogenizing the glass so that the components are evenly distributed throughout the paste and the gas is fully released. Homogenization avoids the problem of streaks appearing in the lens. Chemical agents are used to release the gases, in particular arsenic pentoxide (As2O5), which decomposes into arsenic trioxide (As2O3), releasing oxygen which combines with the other elements and gases released, causing the bubbles remaining in the paste to rise.
Defects such as bubbles, streaks, inclusions and discolorations can appear as a result of the glass melting process. Bubbles result from insufficient refining, streaks from glass heterogeneity (the glass has a different refractive index locally, causing distortion), inclusions may come from glass that has crystallized locally or from fragments of the vessels used for melting, glass discoloration originates from insufficient purity of the mixed products.
The tempering process is reserved for glass whose structure is to be hardened. Glass used for optics is often fragile and thin, so it is not tempered. Optical fibers are tempered after drawing, to give them sufficient mechanical strength.
Annealing consists in slowly cooling a glass in a controlled manner from a certain temperature at which it has begun to solidify (around 1,000 °C for silica glass or 450 °C for soda-lime glass, for example). Annealing is necessary to eliminate internal stresses in the material that may have arisen during melting (impurities, streaks, bubbles, etc.) and to prevent uneven cooling in a material, with internal parts taking longer to heat and cool. The annealing time ranges from a hundred to a thousand hours, depending on the quantity of glass to be annealed and its composition.
Types of glass
The progressive development of the optical glass industry has led to the creation of new lens families. Lenses can be differentiated by their main components, which give them their mechanical, thermal and optical characteristics.
In addition to the two main glass groups, flint and crown, based essentially on SiO2 silica or oxides, other groups exist, such as halide glasses and chalcogenide glasses (excluding oxygen).
The following tables summarize most glass families and their composition. Each composition has its own particular properties and defects. Increasing the index often requires sacrificing transmission in the ultraviolet, and although research since the early days of glassmaking has considerably improved this state of affairs, it is not possible to obtain highly dispersive, low-refractive glasses, or low-dispersive, high-refractive glasses.
Oxide glass
Flints and crowns are glasses composed of oxides, often SiO2 or TiO2 titanates. Their index ranges from 1.4 to 2.4. This large group can be identified by its characteristic transmission profile ranging from 200 nm to 2.5 μm, due to the high gap energies and photon absorption peaks of hydroxyl groups in the infrared.
A variety of oxides are used, the most common being silica-based glasses, but other molecules can also be used to form glassy systems, such as :
germanium dioxide (GeO2) ;
diboron trioxide (B2O3);
phosphorus pentoxide (P2O5);
aluminosilicates and borosilicates;
phosphates.
Phosphate glasses have lower melting temperatures and are more viscous than borosilicate glasses, but they are less resistant to chemical attack and less durable. Glasses based on a phosphate, borate or borophosphate vitreous system are good candidates for athermalization, since their , i.e. the variation in refractive index with temperature, is generally negative. Athermalization consists in compensating for thermal expansion of the material by changing its index. The family of phosphate glasses is particularly well-suited to these possibilities.
Crown glass family
Borosilicate crowns are the most widely produced glass family, and the ones with the best control over final homogeneity. This family includes BK7, the glass widely used in optics. Alkali oxides and boron trioxide B2O3 make it easier to melt silicon dioxide SiO2, which requires very high temperatures to liquefy.
Barium crowns and dense crowns were developed for barium's ability to significantly increase the refractive index without significantly reducing the glass's constringency or ultraviolet transmission, which lead oxide tends to do. Some lenses use a mixture of zinc oxide ZnO and barium oxide BaO.
Crowns, zinc crowns and crown flints are small families of glasses containing a wide variety of oxides (CaO or BaO, ZnO and PbO respectively) to increase hardness or durability.
Phosphate crowns are characterized by their relatively low dispersion and medium index, with generally higher dispersion in the blue, making them useful for correcting chromatism in optical combinations.
Fluorine crowns use fluorine's properties to reduce the dispersion and index of the glass: fluorine's high electronegativity and the smaller radius of fluorine ions are responsible for this. As with phosphate crowns, these lenses are particularly suitable for correcting chromatic aberration, thanks to their partial dispersion in the blue.
Flint glass family
Dense or light flints are long-established families, such as borosilicate crowns, and are used as optical glass as well as crystal for everyday glassmaking. Their main properties derive from the proportion of PbO introduced. PbO increases refractive index while decreasing Abbe number, and also affects partial dispersion. Lead oxide will also increase the density of the glass and reduce its resistance to chemical attack. The ability of the PbO-SiO2 couple to vitrify enables PbO proportions of over 70 mol per 100 to be achieved, which would not be possible if PbO were merely a chemical mesh modifier. Indeed, a high PbO concentration produces tetrahedral PbO4, which can form a glass-like mesh.
The inclusion of PbO has several drawbacks. Firstly, the glasses are slightly yellow due to the high concentration of lead oxide. Secondly, inclusions and impurities such as iron(III) oxide Fe2O3 or chromium(III) oxide Cr2O3 degrade glass transmission to a far greater extent than in soda, potash or lime glasses. Thirdly, a chemical equilibrium between Pb2+ and Pb4+ is established and, in the presence of oxygen-saturated glass, leads to the creation of lead dioxide PbO2, a brown compound that darkens glass. However, this latter coloration can be reversed by a redox transformation of the glass paste, since it does not originate from impurities.
To overcome these problems, titanium dioxide TiO2 and zirconium dioxide ZrO2 can be added, increasing the glass's chemical stability and preserving its ultraviolet transmission.
Barium flints crystallize less easily than other glass families due to the presence of lead(II) oxide (PbO) in the mixture. The higher the proportion of PbO, the higher the refractive index and the lower the melting temperature, so these are glasses which, although very useful for their high indexes, present complications during melting. The BaO in these glasses is sometimes replaced by ZnO.
Lanthanum flints and lanthanum crowns are extended families achieving high refractive indices with medium dispersion. The use of SiO2 in the paste creates crystallization instabilities, a pitfall avoided by replacing silica with boron trioxide B2O3 and divalent oxides. To further increase their refractive index, the use of multiple oxides has become widespread, including gadolinium, yttrium, titanium, niobium, tantalum, tungsten and zirconium oxides (Gd2O3, Y2O3, TiO2, Nb2O5, Ta2O5, WO3 and ZrO2).
Short flints are a family distinguished not by their index or constringency, but by their partial dispersion. Named for their narrow blue spectrum, short flints are also an asset in optical system design for their low blue impact. They are obtained by replacing the lead oxide in flint glasses with Sb2O3 antimony oxide.
Halogenide glass
The first fluoride glasses appeared around 1970 to meet a growing need for mid-infrared transmitting glasses. These glasses are composed by replacing the oxygen in oxide glasses with a halogen, fluorine or chlorine, and more rarely with heavy halogens. Their transmission covers the visible and mid-infrared range, from 200 nm to 7 μm, due to the rather high band gap (on average, a fluoride glass has its transmission dip at around 250 nm, due to its band gap of around 5 eV) and the low-frequency vibrations of the heavy-metal fluoride bonds; silica absorption results from vibrations of Si-O bonds at 1.1 × 103 cm−1, whereas fluorozirconate absorption will result from vibrations of Zr-F bonds at a frequency of 0.58 × 103 cm−1, which is why oxide and halide glasses behave so differently in the infrared.
By using rare earths instead of heavy metals, we obtain a rare-earth fluoride glass that transmits even further into the infrared. Another way of transmitting further into the infrared is to make chloride glass instead of fluoride glass, but this reduces the stability of the glass. A type of glass recently developed at the University of Rennes uses a tellurium halide. As the energy gap in the visible is greater, the drop in transmission in the visible advances to 700 nm-1.5 μm, while its transmission improves in the far infrared. As the refractive index of such a glass is very high, it behaves like a chalcogenide glass, with a strong reflection that reduces its transmission.
Fluoride lenses are also useful for their near-UV transmission. Near-UV transmitting glasses are few in number, but include lithium fluoride, calcium fluoride and magnesium fluoride glasses.
Chalcogenide glass
Chalcogenide glasses have been specifically developed since the 1980s to improve the infrared transmission of optical glasses. Oxygen is replaced by another chalcogen (sulfur, selenium, tellurium), and silicon is replaced by heavier metals such as germanium, arsenic, antimony and others. Their index is greater than 2, and they appear black due to their weak gap and multiple absorption bands in the visible range. The transmission of these glasses ranges from 1 μm to 12 μm, but is lower than that of oxide or halide glasses due to their very high refractive index, which results in a high reflection coefficient.
This group can be divided into two families: glasses that can be doped with rare-earth ions or not. The former are mainly composed of germanium and gallium sulfides and selenides, while the latter, although not doped, offer the best transmission performance in the far infrared.
Classical glass designations
The field of optical lenses encompasses a multitude of materials with extremely diverse properties and equally diverse applications. Nevertheless, it is generally accepted that optical lenses fall into several major families. A large proportion of optical lenses are so-called "classic" lenses, designed for applications such as imaging and filtering. Smaller families of lenses are also part of the optical glass family, such as optical fibers, or so-called "active" lenses for applications in nonlinear optics or acousto-optics, for example.
Special glasses
Fused quartz
Quartz glass is distinguished from other optical glass by the source of the material used in its manufacture. Many manufacturers produce quartz glass, but the differences lie mainly in the nature of the impurities and the water content. These differences give each quartz glass its own special characteristics, such as transmission and resistance to chemical attack.
Quartz glass is made from a single material: silica. Its main properties are low expansion (α≈0.5 × 10−6 K−1), high thermal stability (up to 1,000 K) and transmission in the ultraviolet and infrared, which can be adapted as required.
Optical filter
Filters are glasses designed to transmit only certain parts of the spectrum of incident light. A filter can be colorless, a simple optical glass whose transmission drop serves to cut off wavelengths beyond a certain value, or colored in various ways, by the introduction of heavy metal or rare-earth ions, by molecular coloration or even by a colloidal suspension. Filter glasses show noticeable photoluminescence.
Optical filters in colored glass take the form of a blade with a parallel face and a thickness that depends on the transmission qualities required; like electronic filters, they are referred to as high-pass, low-pass, band-pass or notch filters.
Laser lenses
Several types of glass are used for lasers, including Li2O-CaO-SiO2 glasses for their resistance to thermal shock, and potassium-barium-phosphate glasses, whose effective cross-section is large enough for stimulated emission. The addition of sodium, lithium or aluminum oxides drastically reduces distortion. These glasses are athermalized. In addition to these two types of glass, lithium-aluminum phosphates can be used. These are treated by ion exchange and are particularly resistant, making them ideal for applications where the average laser power is very high (e.g. femtosecond pulsed lasers), or fluorophosphates, which have a slightly non-linear index.
These Nd3+-doped glasses are used as active laser medium.
Gradient index lenses
Gradient-index lenses exploit the special properties of light propagation in a variable-index medium. In 1854, James Clerk Maxwell invented the "Fisheye lens" in response to a problem from the Irish Academy asking for the refractive index of an image-perfect material. This theoretical lens, spherical in shape, has an index of the form where is the refractive index of the glass at a point on the spherical lens and the radius of this lens; it enables any point on its surface to be imaged perfectly at another point diametrically opposite. A generalization of this spherical lens was proposed in 1966 by Rudolf Karl Lüneburg (de), using a different index profile. In 1905, Robert Williams Wood developed a lens consisting of a blade with a parallel face whose index varies parabolically, with the extremum of the index lying on the axis of revolution of the component. The Wood lens can be used to focus or diverge rays, just like a conventional lens.
Since around 1970, glass manufacturing technology has made it possible to develop, qualify and machine graded-index glasses. Two main uses for graded-index glasses are in telecommunications, with optical fibers, and in imaging, with lenses machined from graded-index material. Gradients can also be divided into three types of profile: spherical gradients, cylindrical gradients and axial gradients.
There are several techniques for producing graded-index glass: neutron bombardment, ion filling or glass layer superposition. Depending on the technique used, the gradient will be stronger or weaker, and its profile more or less controlled. Injection or ionic filling methods can produce gradients of 10 to 50 mm, with an index amplitude of 0.04. Neutron bombardment and chemical vapor deposition methods produce shallow gradients (approx. 100 μm) of low amplitude. For larger gradients, there is partial lens polymerization of a monomer reacting to UV exposure (gradients of around one hundred millimeters for an index amplitude of 0, 01), or superimposing and then partially melting layers of borosilicate or flint glass (lanthanum-containing glasses are not suitable for this technique due to their recrystallization problems and thermal instability). A final technique consists of melting and then rotating the paste so that a material gradient, and therefore an index gradient, is established in the glass.
Doped lenses
Certain extreme environments are not conducive to the use of conventional lenses; when the system is exposed to far-field UV radiation (X, gamma, etc.) or particle fluxes such as alpha or beta, a drop in lens transmission is observed, due to discoloration of the material. Generally speaking, electromagnetic radiation causes a drop in blue transmission, a phenomenon known as solarization. As this is detrimental to system performance, it was necessary to develop new types of radiation-resistant lenses.
Radiation has a variety of effects: ionization, electron or hole capture, fission of Si-O bonds, etc. These effects can easily be amplified by the presence of impurities that change the valence of molecules or concentrate radiation, causing local degradation of the glass.
In order to reduce the drop in glass transmission and performance, they are doped with CeO2, which slightly shifts the glass's transmission drop, but makes it virtually impossible to feel the effects of radiation on the glass's optical performance.
Other glasses
In addition to the lenses already mentioned, all of which are specific in their design or use, there are also special glass-like materials.
These include athermalized lenses, which are produced in such a way that the optical path through the lens is independent of temperature. Note that the difference in optical path as a function of temperature is determined by the thickness of the glass, the coefficient of thermal expansion, the index, the temperature and the thermo-optical coefficient. Athermalized glasses can be found in the fluorinated crowns, phosphate crowns, dense crowns, barium and titanium flints and other families.
Glass-ceramics or ceramic glasses are glasses in which the crystal-forming process has been stimulated over a long, complex heating period. The addition of crystals to initiate crystallization results in a glass with a crystallized proportion ranging from 50 to 90%. Depending on the crystals incorporated and the proportion of glass in the ceramic glass, the properties will differ. Generally speaking, ceramic glass is highly resistant to thermal shock and has near-zero thermal expansion (Schott AG's Zerodur, for example, was used specifically for the Very Large Telescope for these thermal properties).
Glass quality
There are numerous standards for optical components, the aim of which is to unify the notations and tolerances applied to components, and to define optical quality standards. There are two main standards: MIL (American military standard) and ISO (international standard). In France, the AFNOR standard is very similar to the ISO standard, as the Union de normalisation de la mécanique is keen to conform as closely as possible to ISO publications.
The MIL and ISO standards cover a very wide field, and both standardize lenses, their defects, surface treatments, test methods and schematic representations.
Manufacturers
There are a number of manufacturers of special lenses for the various fields of optics, whose catalogs offer a wide choice of optical lenses and special lenses, sometimes in addition to filters and active lenses and crystals. Since 1980, however, catalogs have tended to reduce the choice, although optical design tools continue to include catalogs that no longer exist. Manufacturers include the following:
Schott AG
Heraeus Quarzglas
Ohara Corporation
Hoya Corporation
Corning Inc. : Lens catalog not available, but Corning lenses remain available on optical design software and production of special lenses continues.
Pilkington : has refocused its catalog on ophthalmic and flat lenses.
Sumita Optical Glass
Hikari Glass : a Nikon subsidiary producing optical lenses.
OAO Lytkarinski Zavod Optitcheskogo Stekla
CDGM
In addition to catalogs of optical glass and various materials, other manufacturers also sell active or special optical glass. Examples include graded-index glass, used to focus light beams in optical fibers; optical fibers, which in a significant proportion of cases are spun optical glass wires; and optical filters. These products can be found in the catalogs of a larger number of manufacturers, a non-exhaustive but relevant list of which can be found in the same catalogs selected by optical design software:
3M Precision Optics
Archer Optx
Coherent
CVI
Edmund Industrial Optic
Esco
Geltech
ISP Optics
JML
LightPath Technologies
Linos Photonics
Melles Griot
Midwest Optical
Newport Glass
NSG America
Optics for Research
OptoSigma
Philips
Quantum
Rolyn Optics
Ross Optical
Special Optics
Thorlabs
Applications
Optical glasses are mainly used in many optical instruments, as lenses or mirrors. These include, but are not limited to, telescopes, microscopes, photographic lenses and viewfinder lenses. Other possible optical systems include collimators and eyepieces.
Optical lenses, especially ophthalmic lenses, are used for prescription glasses. Glasses can also be made of photochromic glass, whose tint changes according to radiation.
Optical glasses are used for other, much more diverse and specialized applications, such as high-energy particle detectors (glasses detecting Cherenkov radiation, scintillation effects, etc.) and nuclear applications, such as on-board optics in systems subjected to radiation, for example.
Optical glass can be spun to form an optical fiber or form graded-index lenses (SELFOC lens or Geltech lenses) for injection into these same fibers.
Optical glass in one form or another, doped or undoped, can be used as an amplifying medium for lasers.
Last but not least, microlithography, using ultraviolet-transmitting glasses such as Schott's FK5HT (Flint crown), LF5HT (Flint light) or LLF1HT (Flint extra light), named i-line glasses by the company after the ray i of mercury.
Notes
References
Further reading
Bibliography
Publications
Articles
External links
Official records: LCCN GND Japan Israel Czech Republic
"How the generic optical glass code works" archive, on Newport Glass, 2003 (accessed March 12, 2012)
"Cross reference list between similar glasses" archive [PDF], on Ohara corp, 2012 (accessed March 12, 2012)
"Optical glass" archive [PDF], on Hoya, 2012 (consulted on March 12, 2012)
"Sumita Optical Glass" archive [PDF], on Sumita, 2012 (accessed March 12, 2012)
"Potapenko special glass" archive, on opticalglass.com.ua, 2012 (accessed March 12, 2012)
Transmittance of optical glass, Schott AG, coll. "Technical information" (no. 35), October 2005, 12 p. (read online archive)
Fluorescence of optical glass, Schott AG, coll. "Technical information" (no. 36), August 2010 (read online archive)
Stress in optical glass, Schott AG, coll. "Technical information" (no. 27), July 2004 (read online archive)
"Norme ISO 10110" archive, International Organization for Standardization.
"Info Vitrail" archive, on infovitrail.com, SARL ARBO-COM (accessed July 1, 2012) Site featuring a fairly comprehensive glossary of technical glassmaking terms.
"Verre online" archive, on verreonline.fr, Institut du verre (consulted July 1, 2012)
Glass
Infrared
Light
Refraction
Quartz
Glass makers | Optical glass | [
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"Chemistry"
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"Homogeneous chemical mixtures",
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"Amorphous solids",
"Infrared"
] |
74,757,254 | https://en.wikipedia.org/wiki/Phaeotremella%20fimbriata | Phaeotremella fimbriata is a species of fungus in the family Phaeotremellaceae. It produces blackish, frondose, gelatinous basidiocarps (fruit bodies) and is parasitic on the mycelium of Stereum rugosum, a fungus that grows on dead attached and recently fallen branches of broad-leaved trees. It is widespread in northern Europe. Prior to 2017, the species was generally considered a synonym of Tremella foliacea, but this latter species (now known as Phaeotremella foliacea) is restricted to conifers. Phaeotremella frondosa is a similar-looking but paler, brown species on broad-leaved trees and occurs in North America as well as Europe.
Taxonomy
Tremella fimbriata was first published in 1800 by South African-born mycologist Christiaan Hendrik Persoon, together with Tremella foliacea. Most subsequent authors considered the two species synonymous, with T. foliacea the preferred name (more rarely T. fimbriata). It was not until molecular research, based on cladistic analysis of DNA sequences, revealed that Tremella foliacea sensu lato covered several similar but distinct species, that the name Phaeotremella fimbriata was distinguished and recognized in its current sense.
Description
Fruit bodies are gelatinous, dark blackish brown becoming black, up to 4 cm (1.5 in) across, and seaweed-like (with branched, undulating fronds). Microscopically, the hyphae are clamped and occur in a dense gelatinous matrix. Haustorial cells arise on the hyphae, producing filaments that attach to and penetrate the hyphae of the host. The basidia are tremelloid (globose to ellipsoid, with oblique to vertical septa), 9 to 14 by 9 to 12 μm, usually unstalked. The basidiospores are mostly ellipsoid, smooth, 5 to 8 by 4.5 to 6.5 μm, and germinate by hyphal tube or by yeast cells.
Similar species
Phaeotremella frondosa is a common and widespread species parasitizing Stereum hirsutum and other Stereum species on broad-leaved trees. It produces larger and paler brown fruit bodies than Phaeotremella fimbriata and has slightly larger spores (6 to 10 by 5 to 9 μm). Phaeotremella foliacea parasitizes Stereum sanguinolentum on conifers.
Habitat and distribution
Phaeotremella fimbriata is a parasite of Stereum rugosum, growing on the host's hyphae in the wood rather than on the host's fruit bodies. Following its hosts, fruit bodies of P. fimbriata are typically found on dead, attached or recently fallen branches of broad-leaved trees, particularly alder.
The species is currently known only from northern Europe.
References
External links
Tremellomycetes
Fungi described in 1800
Fungi of Europe
Taxa named by Christiaan Hendrik Persoon
Fungus species | Phaeotremella fimbriata | [
"Biology"
] | 683 | [
"Fungi",
"Fungus species"
] |
74,759,951 | https://en.wikipedia.org/wiki/Sanglifehrin | Sanglifehrin A is a polyketide natural product found to potently inhibit cyclophilins and have immunosuppressive activity.
History
Isolation and characterisation of Sanglifehrins, produced by fermentation of Streptomyces sp. A92-308110 was first published by JJ Sanglier and T Fehr in 1999.
Structure
Sanglifehrins are mixed polyketide / non-ribosomal peptides, and their biosynthesis requires a modular type I polyketide synthase, with one module of non-ribosomal peptide synthetase, which incorporates phenylalanine, later converted by a hydroxylase to meta-tyrosine.
See also
Rapamycin
Epothilone
References
Polyketides
Lactams
Spiro compounds
Ketones
Polyols
Conjugated dienes
Diazinanes | Sanglifehrin | [
"Chemistry"
] | 183 | [
"Biomolecules by chemical classification",
"Natural products",
"Ketones",
"Functional groups",
"Organic compounds",
"Polyketides",
"Spiro compounds"
] |
74,760,198 | https://en.wikipedia.org/wiki/Nucleolus%20%28game%20theory%29 | In cooperative game theory, the nucleolus of a cooperative game is the solution (i.e., allocation of payments to players) that maximizes the smallest excess of a coalition (where the excess is the difference between the payment given to the coalition and the value the coalition could get by deviating). Subject to that, the nucleolus satisfies the second-smallest excess; and so on, in the leximin order. The nucleolus was introduced by David Schmeidler in 1969.
Background
In a cooperative game, there is a set N of players, who can cooperate and form coalitions. Each coalition S (subset of players) has a value, which is the profit that S can make if they coopereate on their own, ignoring the other players in N. The players opt to form the grand coalition - a coalition containing all players in N. The question then arises, how should the value of the grand coalition be allocated among the players? Each such allocation of value is called a solution or a payoff vector.
The excess of any coalition S from a given payoff-vector x is the difference between the total payoff to members of S under x, and the value of S. Note that the excess can be positive, negative or zero. Intuitively, a solution in which all coalitions have a higher excess is more stable, since coalitions are less incentivized to deviate from the grand-coalition.
The nucleolus is a single solution, for which the vector of excesses of all coalitions is largest in the leximin order. Intuitively, the nucleolus maximizes the stability of the solution by minimizing the incentives of coalitions to deviate.
Definitions
A cooperative game is represented by a value function , which assigns a value to each possible coalition (each subset of players). A solution to a cooperative game is a vector , which assigns a payoff to each player in N. A solution should satisfy the basic requirement of efficiency: the sum of payoffs should exactly equal v(N) -- the value of the grand coalition. A payoff solution satisfying this condition is called an imputation.
The excess of a payoff-vector for a coalition is the quantity . That is, the profit that players in coalition obtain if they remain in the grand coalition and do not deviate.
Let be the vector of excesses of , arranged in non-decreasing order: . For two payoff vectors , we say is lexicographically smaller than if for some index , we have and . The nucleolus of is the lexicographically largest imputation, based on this ordering. In other words, the nucleolus is an imputation whose excesses-vector is largest in the leximin order. It can be represented by the following optimization problem: where k = 2N = the number of possible coalitions.
Properties
The nucleolus is always unique. See and Section II.7 of for a proof.
Relation to other solution concepts
The core is, by definition, the set of all imputations in which the excess of each coalition is at least 0. Therefore, if the core is non-empty, the nucleolus is in the core.
When the core is empty, it is natural to consider an approximation: the ε-core is the set of all imputations in which the excess of each coalition is at least -ε. For every ε, if the ε-core is non-empty, then the nucleolus is in the ε-core.
The least-core is the smallest nonempty ε-core (for the smallest ε for which the ε-core is non-empty). The nucleolus is always in the least-core. In fact, the nucleolus can be seen as a refinement of the least-core. Starting with the least-core, record the coalitions for which the excess is exactly -ε. Find a subset of the least-core in which the smallest excess of the other coalitions is as large as possible. Repeat this process as many times as necessary until all coalitions have been recorded. The resulting payoff vector is the nucleolus.
The nucleolus is always in the kernel, and since the kernel is contained in the bargaining set, it is always in the bargaining set (see for details.)
Computation
General games
A general cooperative game among n players is characterized by 2n values - one value for each possible coalition. The nucleolus of a general game can be computed by any algorithm for lexicographic max-min optimization. These algorithms usually require to solve linear programs with one constraint for each objective value, plus some additional constraints. Therefore, the number of constraints is O(2n). The number of iterations required by the more efficient algorithms is at most n, so the run-time is O(n 2n).
If the cooperative game is given by enumerating all coalitions' values, then the input size is 2n , and so the above algorithms run in time polynomial in the input size. But when n is large, even representing such a game is computationally intensive, and there is more interest in classes of cooperative games that have a compact representation.
Weighted voting games
In a weighted voting game, each player has a weight. The weight of a coalition is the sum of weights of its members. A coalition can force a decision if its total weight is above a certain threshold. Therefore, the value of a coalition is 1 if its value is above the threshold, and 0 if its value is below the threshold. A weighted voting game can be represented by only n+1 values: a weight for each player, and the threshold.
In a weighted voting game, the core can be computed in time polynomial in n. In contrast, the least-core is NP-hard, but has a pseudopolynomial time algorithm - an algorithm polynomial in n and the maximum weight W. Similarly, the nucleolus is NP-hard, but has a pseudopolynomial time algorithm. The proof relies on solving successive exponential-sized linear programs, by constructing dynamic-programming based separation oracles.
Minimum-cost spanning tree games
In a minimum-cost spanning-tree game, each player is a node in a complete graph. The graph contains an additional node s (the supply node). Each edge in the graph has a cost. The cost of each coalition S is the minimum cost of a spanning tree connecting all nodes in S to the supply node s. The value of S is minus the cost of S. Thus, a MCST game can be represented by O(n2) values.
Computing the nucleolus on general MCST games is NP-hard, but it can be computed in polynomial time if the underlying network is a tree.
Weighted cooperative matching games
In weighted cooperative matching games, the nucleolus can be computed in polynomial time.
Implicitly-given value function
In some games, the value of each coalition is not given explicitly, but it can be computed by solving a set of mathematical programming problems. Using a constraint generation approach, it is possible to compute only the values of coalitions that are required for the nucleolus. This allows to compute the nucleolus efficiently in practice, when there are at most 20 players.
Potters, Reijnierse and Ansing present a fast algorithm for computing the nucleolus using the prolonged simplex algorithm.
Using the prekernel
If the prekernel of a cooperative game contains exactly one core vector, then the nucleolus can be computed efficiently. The algorithm is based on the ellipsoid method and on a scheme of Maschler for approximating the prekernel.
Mistakes in computing the nucleolus
Guajardo and Jornsten have found mistakes in the application of linear programming and duality to computing the nucleolus.
Notes
See also
Contested garment rule
The nucleolus vs. the least core
References
Cooperative games
Game theory equilibrium concepts | Nucleolus (game theory) | [
"Mathematics"
] | 1,663 | [
"Game theory",
"Game theory equilibrium concepts",
"Cooperative games"
] |
74,760,216 | https://en.wikipedia.org/wiki/Opioids%20and%20pregnancy | Opioid use during pregnancy can have significant implications for both the mother and the developing fetus.
Opioids are a class of drugs that include prescription painkillers (e.g., oxycodone, hydrocodone) and illicit substances like heroin. Opioid use during pregnancy is associated with an increased risk of complications, including an elevated risk of preterm birth, low birth weight, intrauterine growth restriction, and stillbirth. Opioids are substances that can cross the placenta, exposing the developing fetus to the drugs. This exposure can potentially lead to various adverse effects on fetal development, including an increased risk of birth defects. One of the most well-known consequences of maternal opioid use during pregnancy is the risk of neonatal abstinence syndrome (NAS). NAS occurs when the newborn experiences withdrawal symptoms after birth due to exposure to opioids in the womb. Maternal opioid use during pregnancy can also have long-term effects on the child's development. These effects may include cognitive and behavioral problems, as well as an increased risk of substance use disorders later in life. Current guidelines recommend that opioid use disorder in pregnancy be treated with opioid agonist pharmacotherapy consisting of methadone or buprenorphine to substitute for the drug of abuse.
Pain management and concerns
Opioid usage is common among pregnant women and is on the rise. Opioid drugs are used for various reasons during pregnancy, with pain being a frequent issue. Conditions like pelvic and lower back pain, occurring in around 68 to 72% of pregnancies, are commonly treated with these medications. Moreover, other sources of pain like muscle aches, migraines, and joint pain are commonly reported during pregnancy.
However, when it comes to chronic pain, guidelines from the American Pain Society recommend discussing the advantages and disadvantages of chronic opioid therapy with women and, if possible, limiting or avoiding opioid use during pregnancy due to potential risks to the fetus. Even though there is evidence suggesting harmful impacts on fetal development caused by prescription opioids, research conducted in both Europe and the United States consistently shows elevated levels of prescription opioid use during pregnancy, whether it's for medical reasons or due to opioid dependency. It's important to note that prescription opioids encompass a range of medications, and the potential effects on the fetus may differ between different medications within the same drug class.
Complications
Opioids can cross both the placental and blood-brain barriers, which poses risks to fetuses and newborns exposed to these drugs before birth. This exposure to opioids during pregnancy can lead to potential obstetric complications, including spontaneous abortion, abruption of the placenta, pre-eclampsia, prelabor rupture of membranes, and fetal death. There are also adverse outcomes in newborns associated with maternal opioid use during pregnancy, such as sudden infant death syndrome, being smaller than expected for their gestational age, preterm birth, lower birth weight, and reduced head size. Neonatal abstinence syndrome is a commonly observed issue in newborns who were exposed to opioids before birth.
Birth defects
The use of opioids in the early stages of pregnancy is associated with an elevated risk of congenital anomalies. Specifically, there is a two-fold increased likelihood of certain birth defects, including congenital heart defects, gastroschisis, and neural tube defects. The risk of preterm birth and neonatal complications is reduced to some extent when dextropropoxyphene or codeine is used in comparison to other opioid analgesics.
Neurodevelopment
The potential impact on the neurodevelopment of infants exposed to opioids before birth is another significant concern. A recent meta-analysis revealed noteworthy deficiencies in cognitive, psychomotor, and behavioral abilities in infants and preschool-aged children who had experienced chronic intrauterine opioid exposure. Children who experienced neonatal abstinence syndrome were notably more prone to hospitalizations due to cognitive impairments, communication, speech, or language disorders, autism spectrum disorder, and behavioral problems, particularly those concerning emotional control.
Neonatal withdrawal
Neonatal abstinence syndrome occurs when newborns go through withdrawal from opiates and is linked to dysfunction in the central and autonomic nervous systems, the respiratory system, and the gastrointestinal tract. Additionally, there is an elevated risk of neonatal abstinence syndrome associated with the medical use of certain opioid analgesics, such as tramadol, codeine, and propoxyphene.
Management
Pregnant women with opioid use disorder have treatment options including methadone, naltrexone, or buprenorphine to decrease opioid usage and enhance treatment adherence. Current guidelines suggest that methadone and buprenorphine are equally viable choices. Nevertheless, recent research suggests that buprenorphine may offer certain advantages over methadone. Current guidelines recommend that pregnant women with opioid use disorder be treated with opioid agonist pharmacotherapy consisting of methadone or buprenorphine to substitute for the drug of abuse.
See also
Alcohol and pregnancy
Cannabis in pregnancy
References
External links
Drugs and pregnancy
Opioids
Teratogens | Opioids and pregnancy | [
"Chemistry"
] | 1,103 | [
"Teratogens"
] |
74,760,455 | https://en.wikipedia.org/wiki/Purpureocillium%20roseum | Purpureocillium roseum is a species of fungus in the genus Purpureocillium in the order of Hypocreales.
References
Ophiocordycipitaceae
Fungi described in 2020
Fungus species | Purpureocillium roseum | [
"Biology"
] | 48 | [
"Fungi",
"Fungus species"
] |
74,760,499 | https://en.wikipedia.org/wiki/Purpureocillium%20lavendulum | Purpureocillium lavendulum is a species of fungus in the genus Purpureocillium in the order of Hypocreales.
References
Ophiocordycipitaceae
Fungi described in 2012
Fungus species | Purpureocillium lavendulum | [
"Biology"
] | 50 | [
"Fungi",
"Fungus species"
] |
74,760,523 | https://en.wikipedia.org/wiki/Purpureocillium%20sodanum | Purpureocillium sodanum is a species of fungus in the genus Purpureocillium in the order of Hypocreales.
References
Ophiocordycipitaceae
Fungi described in 2016
Fungus species | Purpureocillium sodanum | [
"Biology"
] | 48 | [
"Fungi",
"Fungus species"
] |
74,760,709 | https://en.wikipedia.org/wiki/Purpureocillium%20takamizusanense | Purpureocillium takamizusanense is a species of fungus in the genus Purpureocillium in the order of Hypocreales.
Biology
P. takamizusanense is the holomorph designation of this species. The anamorph form Isaria takamizusanensis and it's teleomorph Cordyceps rogamimontana were originally described to the genera Isaria and Cordyceps respectively., before their connection was shown in 2015.
P. takamizusanense has been collected from various cicada species in Japan. Species include Hyalessa maculaticollis, from which the holotype was sampled in 1939, and Meimuna opalifera.
References
Ophiocordycipitaceae
Fungi described in 1941
Fungi of Japan
Fungus species | Purpureocillium takamizusanense | [
"Biology"
] | 175 | [
"Fungi",
"Fungus species"
] |
74,761,363 | https://en.wikipedia.org/wiki/Paecilomyces%20niveus | Paecilomyces niveus is a species of fungus in the genus Paecilomyces in the order of Eurotiales.
References
niveus
Fungi described in 1909
Fungus species | Paecilomyces niveus | [
"Biology"
] | 41 | [
"Fungi",
"Fungus species"
] |
74,761,425 | https://en.wikipedia.org/wiki/Paecilomyces%20lagunculariae | Paecilomyces lagunculariae is a species of fungus in the genus Paecilomyces in the order of Eurotiales.
References
lagunculariae
Fungi described in 1968
Fungus species | Paecilomyces lagunculariae | [
"Biology"
] | 43 | [
"Fungi",
"Fungus species"
] |
74,761,545 | https://en.wikipedia.org/wiki/Thermoascus%20verrucosus | Thermoascus verrucosus is a species of fungus in the genus Thermoascus in the order of Eurotiales.
References
Thermoascaceae
Fungi described in 1975
Fungus species | Thermoascus verrucosus | [
"Biology"
] | 45 | [
"Fungi",
"Fungus species"
] |
74,761,665 | https://en.wikipedia.org/wiki/Pseudohamigera%20striata | Pseudohamigera striata is a species of fungus in the genus Pseudohamigera in the order of Eurotiales.
References
Aspergillaceae
Fungi described in 1948
Fungus species | Pseudohamigera striata | [
"Biology"
] | 40 | [
"Fungi",
"Fungus species"
] |
68,975,789 | https://en.wikipedia.org/wiki/Qajar%20coffee | Qajar coffee () was a type of poisoned coffee used in the court of Qajar Iran to kill the enemies of the government.
This method of removing opponents became popular especially after the reign of Nasereddin Shah Qajar, notably his son Zellossoltan was notorious in using cyanide, arsenic acid or strychnine poisoned coffee to remove those who opposed him.
Victims
These people are said to have died by consuming Qajar coffee:
Agha Reza Khan Eghbalossaltane
Mirza Agha Khan Nuri, grand vizier
Mansur Nezam, constitutionalist and tribal leader
Abolfath Khan
Mirza Mohammad Khan Sepahsalar, grand vizier
Hossein Gholi Khan Ilkhani
Mirza Habibollah Khan Moshirolmolk, politician
Mirza Ali Khan, Treasurer
Mirza Mohammad Khan Aminoddole
Mirza Mohammad Hasan Sheikholeslam, cleric
References
Poisons
Execution methods
Coffee
Arsenic
Qajar Iran | Qajar coffee | [
"Environmental_science"
] | 196 | [
"Poisons",
"Toxicology"
] |
68,976,588 | https://en.wikipedia.org/wiki/SeaBASS%20%28data%20archive%29 | The SeaWiFS Bio-optical Archive and Storage System (SeaBASS) is a data archive of in situ oceanographic data used to support satellite remote sensing research of ocean color. SeaBASS is used for developing algorithms for satellite-derived variables (such as chlorophyll-a concentration) and for validating or “ground-truthing” satellite-derived data products. The acronym begins with “S” for SeaWiFS, because the data repository began in the 1990s around the time of the launch of the SeaWiFS satellite sensor, and the same data archive has been used ever since. Oceanography projects funded by the NASA Earth Science program are required to upload data collected on research campaigns to the SeaBASS data repository to increase the volume of open-access data available to the public. As of 2021 the data archive contained information from thousands of field campaigns uploaded by over 100 principal investigators.
See also
EOSDIS
Ocean color
Ocean observations
Ocean optics
Water remote sensing
References
External links
NASA SeaBASS Official Website
Earth observation
Environmental data
Environmental science databases
Oceanography | SeaBASS (data archive) | [
"Physics",
"Environmental_science"
] | 219 | [
"Oceanography",
"Hydrology",
"Applied and interdisciplinary physics",
"Environmental science databases"
] |
68,976,965 | https://en.wikipedia.org/wiki/Organic%20thiocyanates | Organic thiocyanates are organic compounds containing the functional group RSCN. the organic group is attached to sulfur: R−S−C≡N has a S–C single bond and a C≡N triple bond.
Organic thiocyanates are valued building blocks. They allow to access efficiently various sulfur containing functional groups and scaffolds.
Synthesis
Several synthesis routes exist, the most common being the reaction between alkyl halides and alkali thiocyanate in aqueous media. Illustrative is the preparation of isopropyl thiocyanate by treatment of isopropyl bromide with sodium thiocyanate in boiling ethanol. The main complication with this route is the competing formation of alkyisothiocyanates. "SN1-type" substrates (e.g., benzyl halides) tend to give the isothiocyanate derivatives.
Some organic thiocyanates are generated by cyanation of some organosulfur compounds. Sulfenyl thiosulfates (RSSO3−) react with alkali metal cyanides to give thiocyanates with displacement of sulfite. This approach has been applied to allyl thiocyanate:
Sulfenyl chlorides (RSCl) also convert to thiocyanates.
Aryl thiocyanates are traditionally produced by the Sandmeyer reaction, which involves combining copper(I) thiocyanate and diazonium salts:
Some arylthiocyanates can also often be obtained by thiocyanogenation, i.e. the reaction of thiocyanogen. This reaction is favored for electron-rich aromatic substrates.
Structure
In methyl thiocyanate, and distances are 116 and 176 pm. By contrast, and distances are 117 and 158 pm in isothiocyanates.
Typical bond angles for are 100°. By contrast in aryl isothiocyanates is 165°. Again, the thiocyanate isomers are quite different with angle near 100°.
In both organic thiocyanate and isothiocyanate isomers the angle approaches 180°.
Reactions
Organic thiocyanates are hydrolyzed to thiocarbamates in the Riemschneider thiocarbamate synthesis.
Electrochemical reduction typically converts thiocyanates to thioates and cyanide, although sometimes it can replace the thiocyanate group as a whole with hydride.
Some thiocyanates isomerize to the isothiocyanates. This reaction is especially rapid for the allyl isothiocyanate:
Likewise, acyl thiocyanates are difficult to synthesize because any excess thiocyanate ion catalyzes isomerization to the acyl isothiocyanate.
See also
Isothiocyanate, isomers of organic thiocyanates with the formula R−N=C=S
Methyl thiocyanate, the simplest organic thiocyanate
References
Functional groups | Organic thiocyanates | [
"Chemistry"
] | 644 | [
"Thiocyanates",
"Functional groups"
] |
68,977,344 | https://en.wikipedia.org/wiki/Isocyanide%20dichloride | Isocyanide dichlorides are organic compounds containing the RN=CCl2 functional group. Classically they are obtained by chlorination of isocyanides. Phenylcarbylamine chloride is a well-characterized example.
Preparation and reactions
Chlorination of organic isothiocyanates is also well established:
RN=C=S + 2Cl2 → RN=CCl2 + SCl2
Alkylisocyanates are chlorinated by phosphorus pentachloride:
RN=C=O + PCl5 → RN=CCl2 + POCl3
Cyanogen chloride also chlorinates to give the isocyanide dichloride:
ClCN + Cl2 → ClN=CCl2
Reactions
Isocyanide dichlorides participate in Friedel-Crafts-like reactions, leading, after hydrolysis, to benzamides:
RN=CCl2 + ArH → RN=C(Cl)Ar + HCl
RN=C(Cl)Ar + H2O → R(H)NC(O)Ar + HCl
References
Functional groups
Isocyanides
Organochlorides | Isocyanide dichloride | [
"Chemistry"
] | 244 | [
"Isocyanides",
"Functional groups"
] |
68,977,795 | https://en.wikipedia.org/wiki/Seiridium%20cardinale | Seiridium cardinale is a species of fungus within the genus of Seiridium, in the Sporocadaceae family.
It is the primary cause of Cypress canker, a fungal disease that affects various species of trees in the genus Cupressus, including Cupressus sempervirens, the Provence cypress. This disease leads to the decline of infected trees and has led to the destruction of millions in central Italy in particular. It causes branch and trunk cankers.
In 2009, it was found in Morocco on Cupressus sempervirens trees.
References
Xylariales
Fungus species | Seiridium cardinale | [
"Biology"
] | 126 | [
"Fungi",
"Fungus species"
] |
68,985,460 | https://en.wikipedia.org/wiki/Avacopan | Avacopan, sold under the brand name Tavneos, is a medication used to treat anti-neutrophil cytoplasmic autoantibody-associated vasculitis. Avacopan is a complement 5a receptor antagonist and a cytochrome P450 3A4 inhibitor.
The most common side effects include nausea (feeling sick), headache, decrease in white blood cell count, upper respiratory tract (nose and throat) infection, diarrhea, vomiting, and nasopharyngitis (inflammation of the nose and throat).
Avacopan was approved for medical use in Japan in September 2021, and in the United States in October 2021. It is the first orally-administered inhibitor of the complement C5a receptor approved by the US Food and Drug Administration (FDA). The FDA considers it to be a first-in-class medication.
Medical uses
In the United States, avacopan is indicated as an adjunctive treatment of adults with severe active anti-neutrophil cytoplasmic autoantibody-associated vasculitis (granulomatosis with polyangiitis and microscopic polyangiitis) in combination with standard therapy including glucocorticoids.
In the European Union, avacopan, in combination with a rituximab or cyclophosphamide regimen, is indicated for the treatment of adults with severe, active granulomatosis with polyangiitis or microscopic polyangiitis.
History
The FDA approved avacopan based on evidence from a clinical trial of 330 participants with severe active anti-neutrophil cytoplasmic autoantibody-associated vasculitis. In the clinical trial, participants were randomly assigned to receive avacopan or placebo for 52 weeks. Participants in the placebo group received a glucocorticoid taper over 20 weeks. Neither the participants nor healthcare providers knew which medication was being given. Participants in both groups received background immunosuppressive treatment (cyclophosphamide or rituximab) and were allowed to receive additional glucocorticoids. The benefit of avacopan in comparison to placebo was assessed by proportion of participants who achieved remission at week 26 and sustained remission at week 52. Data from this trial were also analyzed for the assessment of side effects. The trial was conducted at 143 sites in 18 countries including the United States. This trial assessed both efficacy and safety. In the clinical trial, a greater proportion of participants who received avacopan for one year with other medicines (including glucocorticoids) achieved sustained disease remission compared to participants who received other medicines without avacopan. The proportion of participants who achieved remission after six months of treatment was similar.
Society and culture
Legal status
In November 2021, the Committee for Medicinal Products for Human Use of the European Medicines Agency (EMA) adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Tavneos, intended, in combination with a rituximab or cyclophosphamide regimen, for the treatment of adults with severe, active granulomatosis with polyangiitis or microscopic polyangiitis. The applicant for this medicinal product is Vifor Fresenius Medical Care Renal Pharma France. The EMA considers avacopan to be a first-in-class medicine. Avacopan was approved for medical use in the European Union in January 2022.
The FDA granted the application for avacopan orphan drug designation.
Names
Avacopan is the international nonproprietary name.
References
Further reading
External links
Immunosuppressants
Orphan drugs
Fluoroarenes
Trifluoromethyl compounds
Amides
Anilines
Piperidines
Cyclopentyl compounds | Avacopan | [
"Chemistry"
] | 792 | [
"Amides",
"Functional groups"
] |
68,985,654 | https://en.wikipedia.org/wiki/Comparative%20Biochemistry%20and%20Physiology%20A | Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology is a peer-reviewed scientific journal that covers research in biochemistry and physiology.
External links
Biochemistry journals
Physiology journals
Elsevier academic journals | Comparative Biochemistry and Physiology A | [
"Chemistry"
] | 40 | [
"Biochemistry stubs",
"Biochemistry journals",
"Biochemistry literature",
"Biochemistry journal stubs"
] |
68,985,674 | https://en.wikipedia.org/wiki/Comparative%20Biochemistry%20and%20Physiology%20C | Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology is a peer-reviewed scientific journal that covers research in biochemistry and physiology.
External links
Biochemistry journals
Physiology journals
Elsevier academic journals | Comparative Biochemistry and Physiology C | [
"Chemistry"
] | 41 | [
"Biochemistry stubs",
"Biochemistry journals",
"Biochemistry literature",
"Biochemistry journal stubs"
] |
68,985,700 | https://en.wikipedia.org/wiki/Comparative%20Biochemistry%20and%20Physiology%20D | Comparative Biochemistry and Physiology Part D: Genomics and Proteomics is a peer-reviewed scientific journal that covers research in biochemistry and physiology.
External links
Biochemistry journals
Physiology journals
Elsevier academic journals | Comparative Biochemistry and Physiology D | [
"Chemistry"
] | 40 | [
"Biochemistry stubs",
"Biochemistry journals",
"Biochemistry literature",
"Biochemistry journal stubs"
] |
68,987,530 | https://en.wikipedia.org/wiki/Kennie%20Tsui | Kennie Tsui is a New Zealand chemical and environmental engineer. In July 2021, she was appointed chief executive of the New Zealand Geothermal Association. In December 2024, she was appointed a Companion of the New Zealand Order of Merit, for services to the environment and governance.
Biography
Tsui is the chair of the Wellington branch of Engineering New Zealand. Since 2016, she has been chair of the International Partnership of Geothermal Technologies. In 2019, she was appointed principal analyst for the New Zealand Climate Change Commission. In 2020, she received the Fulton-Downer Gold Medal for her leadership in the engineering industry.
In the 2025 New Year Honours, Tsui was appointed a Companion of the New Zealand Order of Merit, for services to the environment and governance.
References
Living people
21st-century New Zealand engineers
Year of birth missing (living people)
New Zealand chemical engineers
21st-century New Zealand women
Environmental engineers
Companions of the New Zealand Order of Merit
New Zealand women engineers | Kennie Tsui | [
"Chemistry",
"Engineering"
] | 196 | [
"Environmental engineers",
"Environmental engineering"
] |
68,987,959 | https://en.wikipedia.org/wiki/Carlia%20S.%20Westcott | Carlia S. Westcott was an American engineer. She was the first woman to receive a license in Marine Engineering in the United States, in December 1921. She was highlighted on the cover of The Woman Engineer after the New York Times covered her. She was from Seattle, Washington.
Sources
Marine engineers
20th-century American women engineers
20th-century American engineers
Engineers from Seattle
Year of birth missing
Year of death missing | Carlia S. Westcott | [
"Engineering"
] | 84 | [
"Marine engineers",
"Marine engineering"
] |
68,988,573 | https://en.wikipedia.org/wiki/Zella%20McBerty | Zella McBerty (née Helwick; 1879 24 May 1937), was an American businesswoman and engineer, a “better mechanic than any of the other men that she worked with” at Packard Electric.
Early life
Born Zella Helwick in 1879 to a couple from Mineral Ridge, Ohio who died shortly after her birth, she later moved to Warren, Ohio where she married Fred McBerty. They met while working for Packard Electric.
Career
Together the couple bought 'The Federal Machine and Welder Company'. McBerty held the position of chief financial officer of the company and represented it internationally at conferences. In 1923 article the New Castle (Pa.) Herald, commented that “when you hear Mrs. McBerty talk ohms and amperes as well as any electrical engineer, there’s hardly a business realm that a capable woman cannot invade.”
She was the first woman to attend the International Association of Electric Welders conference, which she did when it was held in London in 1924. McBerty was the president of the local Business and Professional Women's Club and an international member of the Women's Engineering Society.
McBerty was also one of very few women to be members of the American Institute of Electrical Engineers.
She died of a heart attack on 24 May 1937 at the age of 58.
Sources
1879 births
1937 deaths
People from Warren County, Ohio
American women engineers
American women business executives
Women's Engineering Society
Electrical engineers
American electrical engineers | Zella McBerty | [
"Engineering"
] | 302 | [
"Electrical engineering",
"Electrical engineers"
] |
68,989,479 | https://en.wikipedia.org/wiki/Bina%20Shaheen%20Siddiqui | Bina Shaheen Siddiqui is a Pakistani chemist and the Director of the H.E.J. Research Institute of Chemistry at the University of Karachi. Siddiqui graduated from the University of Karachi with an MPhil in 1978. In 1980, she graduated from the same university with a PhD in organic chemistry.
She specialises in the chemical components of Pakistan's indigenous plants. She was elected to The World Academy of Sciences in 1989, and was elected a Fellow of the Pakistan Academy of Sciences in 1997. She is also a Fellow of the Chemical Society of Pakistan.
Awards
Dr. Abdus Salam Prize in Chemistry (1986)
Nishan-e-Azmat-e-Ilm Plaque, Karachi University (1989)
Nishan-e-Azmat-e-Danish Plaque, Karachi University (1993)
Nishane- Danish Plaque, Karachi University (1998)
First Prize of the National Book Foundation (1997)
Star Woman of the Year Award and gold medal by Star Girls and Women's Foundation (1997)
Tamgha-i-Imtiaz, Government of Pakistan (2000)
Khwarizmi Award by the President of Islamic Republic of Iran (2001)
Sitara-i-Imtiaz by the Govt. of Pakistan (2004)
Distinguished National Professor (HEC)
Selected publications
Siddiqui B.S., Afshan F., Rasheed M., Kardar N., Begum S., Faizi S. (2002) Medicinal Plants - A Source of Potential Chemicals of Diverse Structures and Biological Activity. In: Şener B. (eds) Biodiversity. Springer, Boston, MA.
References
Pakistani women scientists
Living people
Organic chemists
University of Karachi alumni
Academic staff of the University of Karachi
Women chemists
Year of birth missing (living people) | Bina Shaheen Siddiqui | [
"Chemistry"
] | 367 | [
"Organic chemists"
] |
68,990,413 | https://en.wikipedia.org/wiki/Hardware%20for%20artificial%20intelligence | Specialized computer hardware is often used to execute artificial intelligence (AI) programs faster, and with less energy, such as Lisp machines, neuromorphic engineering, event cameras, and physical neural networks. Since 2017, several consumer grade CPUs and SoCs have on-die NPUs. As of 2023, the market for AI hardware is dominated by GPUs.
Lisp machines
Lisp machines were developed in the late 1970s and early 1980s to make Artificial intelligence programs written in the programming language Lisp run faster.
Dataflow architecture
Dataflow architecture processors used for AI serve various purposes, with varied implementations like the polymorphic dataflow Convolution Engine by Kinara (formerly Deep Vision), structure-driven dataflow by Hailo, and dataflow scheduling by Cerebras.
Component hardware
AI accelerators
Since the 2010s, advances in computer hardware have led to more efficient methods for training deep neural networks that contain many layers of non-linear hidden units and a very large output layer. By 2019, graphics processing units (GPUs), often with AI-specific enhancements, had displaced central processing units (CPUs) as the dominant means to train large-scale commercial cloud AI. OpenAI estimated the hardware compute used in the largest deep learning projects from Alex Net (2012) to Alpha Zero (2017), and found a 300,000-fold increase in the amount of compute needed, with a doubling-time trend of 3.4 months.
Sources
Computer hardware
Artificial intelligence | Hardware for artificial intelligence | [
"Technology",
"Engineering"
] | 303 | [
"Computer engineering",
"Computer hardware",
"Computer systems",
"Computer science",
"Computers"
] |
68,990,485 | https://en.wikipedia.org/wiki/Camp%20Beagle | Camp Beagle is an ongoing protest camp set up in June 2021 by animal rights activists outside of MBR Acres, a breeding facility for beagles used in laboratory research, in Wyton, Cambridgeshire. As of May 2024, It is the longest-lasting protest camp of its kind, where protesters have maintained a permanent presence, as they want the site to be closed down.
Background
MBR Acres is owned by the American company Marshall BioResources (MBR). Up to 2,000 beagles are bred at the facility each year; they are sold at the age of around 16 weeks to be used for drugs and chemical testing. Since 2020, protests have been held around the facility by animal rights movements.
History
The camp was first set up in June 2021; footage of dogs from the facility published by the Daily Mirror led to increased support of the campaign. The protesters argue that the facility is factory farming beagles; MBR has issued a statement saying that the protesters are misinformed and that breeding of animals is essential for medical research. The statement also stated that the facility is both regulated and frequently inspected by the Home Office which enforces strict laws around animal welfare in research facilities.
Actors Ricky Gervais and Peter Egan have voiced their support for the facility to be closed down. In August 2021 The Times Newspaper published a letter signed by in support of MBR Acres and its contribution to medical research to nineteen scientific societies and organizations.
On 28 August, Camp Beagle coordinated a protest with Animal Rebellion at Smithfield Market in London.
15 activists were arrested on 31 August for "suspected obstruction of the highway or of criminal damage."
Following a High Court injunction hearing instigated by MBR Acres, it was ruled, on 5 October, that the camp was allowed to remain, with the provision that activists must remain at least 10 metres from the gates.
In October 2021, a Freedom of Information Request revealed that Cambridge Constabulary spent from 27 June to 14 September 2021 on policing the camp. According to protesters, "more than 40 officers and 10 police vans" were used during a day of transportation in October. The following month, the singer Will Young handcuffed himself to the gates of the facility, describing the facility as a "puppy farm".
In December 2022, activists from Animal Rebellion freed 18 beagles from the facility. Two beagles known as Libby and Love – that were recovered by police – were later returned to the facility, and 14 people were arrested as part of an investigation into burglary and aggravated trespass at the site. In July 2023, nine campaigners were found guilty of aggravated trespass, and were given conditional discharges or fines. The Crown Prosecution Service otherwise dropped charges of burglary against 12 people, stating that "the legal test for going ahead had not been met".
On 25 May 2024, an estimated 400–500 protesters descended upon the camp, as part of a protest billed as 'Operation 1,000', in an attempt to attract 1,000 protesters to the camp. Cambridgeshire police closed the nearby road due to the number of demonstrators in attendance.
See also
Brown Dog Affair
Consort beagles campaign
Save the Hill Grove Cats
Save the Newchurch Guinea Pigs
Stop Huntingdon Animal Cruelty
Shamrock Farm
References
2021 protests
2022 protests
2023 protests
2024 protests
Animal rights protests
Animal testing in the United Kingdom
Animal welfare and rights in England
Anti-vivisection movement
Dog breeding
Dogs in the United Kingdom
Protest camps
Protests in England
Organisations based in Cambridgeshire | Camp Beagle | [
"Chemistry"
] | 709 | [
"Animal testing",
"Anti-vivisection movement",
"Vivisection"
] |
68,991,436 | https://en.wikipedia.org/wiki/Pteronepelys | Pteronepelys, sometimes known as the winged stranger, is an extinct genus of flowering plant of uncertain affinities, which contains the one species, Pteronepelys wehrii. It is known from isolated fossil seeds found in middle Eocene sediments exposed in north central Oregon and Ypresian-age fossils found in Washington, US.
Distribution and paleoecology
Pteronepelys wehrii has been identified from two locations in the Clarno Formation, the leaf layer in the Clarno nut beds, type locality for the species plus the White Cliffs. The nut beds are approximately east of the unincorporated community of Clarno, Oregon, while the White Cliffs locality is south of Clarno, and both considered to be middle Eocene in age. The dating is based on averaging zircon fission track radiometric dating which yielded an age of and Argon–argon dating radiometric dating which yielded a to date. The average of the dates resulted in an age range of . The beds are composed of silica and calcium carbonate cemented tuffaceous sandstones, siltstones, and conglomerates which preserve either a lake delta environment, or alternatively periodic floods and volcanic mudflows preserved with hot spring activity.
Five additional specimens were studied from a location in the Eocene Okanagan Highlands, an outcrop of the Ypresian Klondike Mountain Formation in Republic. The formation preserves an upland lake system surrounded by a mixed conifer–broadleaf forest with nearby volcanism. The pollen flora has notable elements of birch and golden larch, and distinct trace amounts of fir, spruce, cypress, and palm. Wolfe and Tanai (1987) interpreted the forest climate to have been microthermal, having distinct seasonal temperature swings which dipped below freezing in the winters. However, further study has shown the lake system was surrounded by a warm temperate ecosystem that likely had a mesic upper microthermal to lower mesothermal climate, in which winter temperatures rarely dropped low enough for snow, and which were seasonably equitable.
It was likely wind-dispersed seed, and possibly part of the canopy flora of the forests, however the affinities of Pteronepelys with other flowering plants were unknown at the time of description.
History and classification
The Pteronepelys wehrii specimens were studied by paleobotanist Steven R. Manchester of the University of Florida. He published his 1994 type description for P. wehrii in the Journal Palaeontographica Americana. The genus and species were described from a series of type specimens, the holotype specimen OMSI PM018, which was preserved in the paleobotanical collections of the Oregon Museum of Science and Industry in Portland, Oregon, and seven paratype specimens. Of the paratypes, one is housed in the University of Florida collections, a second is in the OMSI collections, with the remaining five in the Burke Museum paleontology collections.
The genus name Pteronepelys is a combination of the Greek word elements Pteron meaning "wing" and epelys roughly translating to "stranger", while Manchester coined the specific epithet wehrii in honor of paleobotanist and artist Wesley Wehr, in recognition of contribution of the Klondike Mountain Formation specimens. The genus has been occasionally given the vernacular name "winged stranger" as a result of the genus name.
Description
Pteronepelys wehrii samaras are elongated and flattened sideways, with an elliptical wing that joins to an ovoid endocarp. The nutlets are with an estimated thickness between . The tip of the nutlet sports four to five short sepals which are with round tips. In the middle of the nutlet tip are two central styles. The wing has a convex lower margin and a convex to straight upper margin which meet at the basal end of the samara at a point where it would have connected to the parent plant. Three veins run the length of the wing, arising from the basal wingtip and merging onto the nutlet. Thick veins follow along the upper margin and cross the midline of the wing, while a third, thin vein curves parallel to the lower margin between the midvein and margin.
References
External links
†
Plants described in 1994
Fossil taxa described in 1994
Eocene plants
Flora of the Northwestern United States
Extinct flora of North America
Eocene life of North America
Prehistoric angiosperm genera
Prehistoric plants of North America
Klondike Mountain Formation
Clarno Formation
Enigmatic angiosperm taxa | Pteronepelys | [
"Biology"
] | 929 | [
"Plants",
"Angiosperms"
] |
70,494,954 | https://en.wikipedia.org/wiki/Phosphide%20bromide | Phosphide bromides or bromide phosphides are compounds containing anions composed of bromide (Br−) and phosphide (P3−) anions. Usually phosphorus is covalently connected into more complex structures. They can be considered as mixed anion compounds. They are in the category of pnictidehalides. Related compounds include the phosphide chlorides, phosphide iodides, nitride bromides, arsenide bromides, and antimonide bromides.
List
References
Phosphides
Mixed anion compounds
Bromides | Phosphide bromide | [
"Physics",
"Chemistry"
] | 131 | [
"Matter",
"Mixed anion compounds",
"Salts",
"Bromides",
"Ions"
] |
70,494,971 | https://en.wikipedia.org/wiki/Arsenide%20bromide | Arsenide bromides or bromide arsenides are compounds containing anions composed of bromide (Br−) and arsenide (As3−). They can be considered as mixed anion compounds. They are in the category of pnictidehalides. Related compounds include the arsenide chlorides, arsenide iodides, phosphide bromides, and antimonide bromides.
List
References
Arsenides
Bromides
Mixed anion compounds | Arsenide bromide | [
"Physics",
"Chemistry"
] | 105 | [
"Matter",
"Mixed anion compounds",
"Salts",
"Bromides",
"Ions"
] |
70,495,008 | https://en.wikipedia.org/wiki/Arsenide%20iodide | Arsenide iodides or iodide arsenides are compounds containing anions composed of iodide (I−) and arsenide (As3−). They can be considered as mixed anion compounds. They are in the category of pnictidehalides. Related compounds include the arsenide chlorides, arsenide bromides, phosphide iodides, and antimonide iodides.
List
References
Arsenides
Iodides
Mixed anion compounds | Arsenide iodide | [
"Physics",
"Chemistry"
] | 107 | [
"Ions",
"Matter",
"Mixed anion compounds"
] |
70,495,664 | https://en.wikipedia.org/wiki/Francesco%20Sciortino | Francesco Sciortino (born December 29, 1960) is an Italian physicist and full professor at Sapienza University of Rome. He has made seminal contributions to statistical physics, including the thermodynamic and dynamic theory of complex fluids like water, colloids, colloidal-polymer mixtures, patchy particles, and DNA-based materials. He is one of the original proponents of the "second liquid critical point" theory of water.
Education
Sciortino was awarded a Ph.D. in physics from the University of Palermo in 1989 working on the coupling between biomolecules and the solvent, and focusing on the role of water's hydrogen bond cooperativity in supramolecular arrangement of biomolecules. After the Ph.D., Sciortino became research assistant in the Center for Polymer Studies of Boston University, working in the group of Prof. H. Eugene Stanley.
Academic career
Following his postdoctoral research position in Boston, in 1992 Sciortino became a researcher in Centro di Ricerca, Sviluppo e Studi Superiori in Sardegna, Cagliari. One year later he moved to Sapienza University of Rome, where he became assistant professor in 1993, associate professor in 2000, and full professor in 2005. He serves as associate editor of the Journal of Chemical Physics.
Research and achievements
Sciortino has made seminal contributions in the field of statistical mechanics and soft condensed matter theory. He is one of the original proponents of the Second Liquid Critical Point Hypothesis for water,. which explains water's anomalous behaviour with the presence of a hidden critical point in supercooled water. Experimental verification of this hypothesis has been obtained numerically in several models of water, and finally confirmed with scattering experiments using X-ray pulses.
Sciortino has worked extensively on the physics of arrested states of matter, making seminal contribution to Mode Coupling theory and the Potential Energy Landscape formalism. He and his collaborators hypothesised a novel type of glass (re-entrant glass) in short-range attractive colloidal systems, and this prediction was later confirmed by several experiments and numerical simulations.
Sciortino and his co-authors were also the first to identify colloidal gels as the outcome of a dynamical arrested phase separation process. His contributions to the physics of reduced valence interactions are numerous: the discovery of empty liquids, equilibrium gels, re-entrant topological transitions in network fluids, among many others
According to Scopus, Sciortino's work has been cited 27315 times, and his H-index is 93. Google Scholar lists 38415 citations and an H-index of 105 . Thanks to these bibliometric indexes, he is ranked among the top 10 Italian Physicists in activity.
References
1960 births
Living people
Computational physicists
20th-century Italian physicists
21st-century Italian physicists | Francesco Sciortino | [
"Physics"
] | 594 | [
"Computational physicists",
"Computational physics"
] |
70,496,364 | https://en.wikipedia.org/wiki/DTA%20GView | DTA GVeiw is a program in which genomes of several organisms can be pulled up on the program to immediately show a list of known genes and where they are located in the genome. It has been referred to as a "google maps" of genomes.
Purpose
The purpose of DTA GVeiw is to collect data of organisms, in the hope of one day engineering microbial organisms to help make mars a suitable place for life.
DARPA, the creator of DTA GVeiw, Hopes one day they will be enabled to "pick and choose" desired genes to create new organisms capable of living on a foreign planet.
References
Terraforming
Genetic engineering
Bioinformatics software | DTA GView | [
"Chemistry",
"Astronomy",
"Engineering",
"Biology"
] | 145 | [
"Planetary engineering",
"Biological engineering",
"Bioinformatics stubs",
"Astrobiology stubs",
"Bioinformatics software",
"Biotechnology stubs",
"Genetic engineering",
"Astronomy stubs",
"Biochemistry stubs",
"Bioinformatics",
"Molecular biology",
"Terraforming"
] |
70,498,906 | https://en.wikipedia.org/wiki/The%20Planetary%20Science%20Journal | The Planetary Science Journal is a peer-reviewed open access scientific journal of astrophysics and astronomy, established in 2020. It is published by IOP Publishing on behalf of the American Astronomical Society. The founding editor-in-chief is Faith Vilas (Planetary Science Institute)
Abstracting and indexing
The journal is abstracted and indexed in Inspec and Scopus.
References
External links
Astrophysics journals
Planetary science journals
IOP Publishing academic journals
English-language journals
American Astronomical Society academic journals
Online-only journals | The Planetary Science Journal | [
"Physics",
"Astronomy"
] | 103 | [
"Astronomy stubs",
"Astrophysics journals",
"Astrophysics",
"Astronomy journal stubs",
"Planetary science stubs"
] |
70,500,178 | https://en.wikipedia.org/wiki/Epanorin | Epanorin is a lichen secondary metabolite with the molecular formula C25H25NO6. Epanorin inhibits the proliferation of MCF-7 cancer cells.
References
Further reading
Lichen products
Biological pigments
Amides
Furanones
Methyl esters | Epanorin | [
"Chemistry",
"Biology"
] | 56 | [
"Natural products",
"Lichen products",
"Functional groups",
"Biological pigments",
"Amides",
"Pigmentation"
] |
70,500,320 | https://en.wikipedia.org/wiki/37%20Camelopardalis | 37 Camelopardalis is a solitary star in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 5.36, allowing it to be seen with the naked eye under ideal conditions. Located about 444 light years away, the star is receding with a heliocentric radial velocity of 30.86 .
37 Camelopardalis has a stellar classification of G8 III, indicating that the object is an ageing yellow giant. It has an angular diameter of , with an actual size of . At present it has 1.43 times the mass of the Sun and shines at 129 times the luminosity of the Sun from its photosphere at an effective temperature of , giving it a yellow orange glow. 37 Cam is a metal poor star with an iron abundance only 32% that of the Sun and spins modestly with a projected rotational velocity of .
References
Camelopardalis
Camelopardalis, 37
G-type giants
Durchmusterung objects
041597
2152
029246 | 37 Camelopardalis | [
"Astronomy"
] | 214 | [
"Camelopardalis",
"Constellations"
] |
70,500,474 | https://en.wikipedia.org/wiki/LG%20K92 | LG K92 is a mid-range Android smartphone manufactured by LG Electronics, announced and released on 29 September 2020.
References
LG Electronics smartphones
Mobile phones introduced in 2020
Android (operating system) devices
Mobile phones with multiple rear cameras | LG K92 | [
"Technology"
] | 51 | [
"Mobile technology stubs",
"Mobile phone stubs"
] |
70,500,748 | https://en.wikipedia.org/wiki/Antimonide%20bromide | Antimonide bromides or bromide antimonides are compounds containing anions composed of bromide (Br−) and antimonide (Sb3−). They can be considered as mixed anion compounds. They are in the category of pnictidehalides. Related compounds include the antimonide chlorides, antimonide iodides, arsenide chlorides, arsenide bromides, arsenide iodides, phosphide chlorides, phosphide bromides, and phosphide iodides. The bromoantimonates have antimony in positive oxidation states.
The antimony can be linked into chains, in which case it has a formal oxidation state of −1. Alternately it can be in pairs as Sb2, with an oxidation state of −2 for each atom.
Many of these compounds are clathrates, whereby there are two interpenetrating structures that are only weakly bound to each other by van der Waals force.
List
References
Bromides
Antimonides
Mixed anion compounds
Clathrates | Antimonide bromide | [
"Physics",
"Chemistry"
] | 227 | [
"Matter",
"Mixed anion compounds",
"Salts",
"Bromides",
"Clathrates",
"Ions"
] |
70,500,920 | https://en.wikipedia.org/wiki/Arsenide%20chloride | Arsenide chlorides or chloride arsenides are compounds containing anions composed of chloride (Cl−) and arsenide (As3−). They can be considered as mixed anion compounds. They are in the category of pnictidehalides. Related compounds include the arsenide bromides, arsenide iodides, phosphide chlorides, and antimonide chlorides.
List
References
Arsenides
Chlorides
Mixed anion compounds | Arsenide chloride | [
"Physics",
"Chemistry"
] | 100 | [
"Matter",
"Chlorides",
"Inorganic compounds",
"Mixed anion compounds",
"Salts",
"Ions"
] |
70,501,237 | https://en.wikipedia.org/wiki/GCD%20matrix | In mathematics, a greatest common divisor matrix (sometimes abbreviated as GCD matrix) is a matrix that may also be referred to as Smith's matrix. The study was initiated by H.J.S. Smith (1875). A new inspiration was begun from the paper of Bourque & Ligh (1992). This led to intensive investigations on singularity and divisibility of GCD type matrices. A brief review of papers on GCD type matrices before that time is presented in .
Definition
Let be a list of positive integers. Then the matrix having the greatest common divisor as its entry is referred to as the GCD matrix on .The LCM matrix is defined analogously.
The study of GCD type matrices originates from who evaluated the determinant of certain GCD and LCM matrices.
Smith showed among others that the determinant of the matrix is , where is Euler's totient function.
Bourque–Ligh conjecture
conjectured that the LCM matrix on a GCD-closed set is nonsingular. This conjecture was shown to be false by and subsequently by . A lattice-theoretic approach is provided by .
The counterexample presented in is and that in is
A counterexample consisting of odd numbers is . Its Hasse diagram is presented on the right below.
The cube-type structures of these sets with respect to the divisibility relation are explained in .
Divisibility
Let be a factor closed set.
Then the GCD matrix divides the LCM matrix in the ring of matrices over the integers, that is there is an integral matrix such that ,
see . Since the matrices and are symmetric, we have . Thus, divisibility from the right coincides with that from the left. We may thus use the term divisibility.
There is in the literature a large number of generalizations and analogues of this basic divisibility result.
Matrix norms
Some results on matrix norms of GCD type matrices are presented in the literature.
Two basic results concern the asymptotic behaviour of the norm of
the GCD and LCM matrix on .
Given , the norm of an matrix is defined as
Let . If , then
where
and for and .
Further, if , then
where
Factorizations
Let be an arithmetical function, and let be a set of distinct positive integers. Then the matrix is referred to as the GCD matrix on associated with .
The LCM matrix on associated with is defined analogously.
One may also use the notations and .
Let be a GCD-closed set.
Then
where is the matrix defined by
and is the diagonal matrix, whose diagonal elements are
Here is the Dirichlet convolution and is the Möbius function.
Further, if is a multiplicative function and always nonzero,
then
where and are the diagonal matrices, whose diagonal elements are
and
If is factor-closed, then and
.
References
Matrix theory
Number theory | GCD matrix | [
"Mathematics"
] | 604 | [
"Discrete mathematics",
"Number theory"
] |
70,502,258 | https://en.wikipedia.org/wiki/Stuttgart%20Computer%20Museum | Stuttgart Computer Museum (Computermuseum der Stuttgarter Informatik) is a collection of calculators, mechanical calculating machines, and analog and digital computers at the Vaihingen campus of University of Stuttgart, Germany established in 1997.
Highlights of the collection include several DEC PDP-8 and DEC PDP-11 models, an IBM 1130, and a LGP-30 vacuum tube-based computer. Many items in the collection are in fully working condition and are available for demonstrations. Since 2020, the museum has hosted a virtual event series called "Evenings at the Computer Museum," showcasing various exhibits and demonstrating their functionality.
The inventory primarily consists of decommissioned systems and their components, as well as various documents such as manuals. For instance, the Karlsruhe University donated an extensive program collection on punched tape along with a PDP-11/10 equipped with a vector graphics unit. A Mincal-523 computing system originated from the Federal Institute of Hydrology in Koblenz. It was acquired in a non-functional state and restored to working order through reverse engineering. In 2021, a PDP-12 was added to the collection, donated by the University Observatory in Vienna.
References
External links
Official website
Computer museums
Museums established in 1997
Computer | Stuttgart Computer Museum | [
"Technology"
] | 253 | [
"Computer museums",
"History of computing"
] |
70,502,475 | https://en.wikipedia.org/wiki/Desert%20kite | Desert kites () are dry stone wall structures found in Southwest Asia (Middle East, but also North Africa, Central Asia and Arabia), which were first discovered from the air during the 1920s. There are over 6,000 known desert kites, with sizes ranging from less than a hundred metres to several kilometres. They typically have a kite shape formed by two convergent "antennae" that run towards an enclosure, all formed by walls of dry stone less than one metre high, but variations exist.
Little is known about their ages, but the few dated examples appear to span the entire Holocene. The majority view on their purpose is that they were used as traps for hunting game animals such as gazelles, which were driven into the kites and hunted there.
Appearance
Desert kites are stone structures with a convergent shape, composed of linear piles of stones. The structures have lengths ranging from less than a hundred metres to several kilometres and heights of less than one metre, even accounting for erosion. There often are gaps in the lines, which were presumably either purposeful (left by the builders) or the consequence of lines being formed by alignments of cairns rather than a continuous row. There are a number of different shapes that are referred to as "desert kites", but one common feature of all such structure are the lines forming two walls ("antennae") that converge into an enclosure ("head") with attached cells. Different regions have different prevalent kite types. Sometimes the existence of these cells is considered essential for a desert kite to be considered as such.
Research published in 2022 has shown that pits several metres deep often lie at the margins of enclosures, which have been interpreted as traps and killing pits. The kites enclose surface areas with a median of , but much larger and much smaller sizes are also known.
They are typically found in areas with elevated but flat topography or topographically complex terrain, but are rare or absent from sloping terrain, mountainous regions, or within endorheic basins, although they occur at the margins of mountains. Often, the terrain within the kite is much more open than the outside terrain, lacking vegetation and rocks. In general, the visibility of the kites from their inside is poor, which appears to be a purposeful feature of their construction; for example, the ends and entrances of the kites often coincide with slope breaks (places where the slope changes). Within a given region, the kites tend to have a preferred orientation. They are absent from humid climates and from certain hyperarid areas, and their use may have been influenced by Holocene climate changes.
Their often enormous size and conspicuousness in arid or semiarid terrain renders them visible in aerial images, while their construction in rough terrain makes them almost invisible on the ground. Sometimes, natural features like cliffs are used in conjunction with the artificial walls to form a kite. Clearing vegetation around the lines or using rocks with a different colour from the background has been documented in volcanic terrain. In Arabia, cairns and linear stone alignments have been found associated with kites.
Dating
Dating kites is difficult; various dating methods like radiocarbon dating and optically stimulated luminescence (OSL) have yielded ages ranging from the early to the late Holocene, and there are sporadic reports of their use in travel records. The early Holocene kites are the most complex man-made structures of that time. Some kites have been overprinted by later archaeological structures, destroyed, eroded or submerged, or built out over time to form more complex shapes. In some places, structures like cairns, tombs or square walls occur alongside kites.
Occurrence
Kites are known from the Middle East and Central Asia, with examples known mainly from Uzbekistan, Kazakhstan, Armenia, Turkey, Iraq, Syria, Lebanon, Israel, Palestine, Jordan, Saudi Arabia, Yemen, Egypt and Libya.
Kites have also been found in Mongolia and South Africa. , there were over 6,000 known kites in Asia and the Middle East, and in some parts of Syria there are as many as 1 kite every , to the point that they are partially overlapping or form complicated structures. Similar large enclosures that were presumably used as traps have been found in Europe, where they were dated to Mesolithic and Neolithic age; North America, where structures known as drive lines have been used into the 19th century AD; South America; and Japan.
Function
Both archaeological studies and ethnographic accounts from the 19th and 20th century indicate that desert kites in the Middle East and North Africa were used as traps for wild game. A minority viewpoint is that they were used for livestock management. The disagreement stems mainly from a lack of factual evidence to support either hypothesis, from disputes on the interpretation of evidence, and from the extinction of traditions involving desert kites. There is almost no evidence of what happened to animals after they were trapped or which animals were targeted, but ethnographic analyses indicate that kites were used to hunt ungulates like gazelles, which live in groups and form defensive formations when threatened. The usage of traps in catching animals in the steppe is mentioned in the Epic of Gilgamesh. The construction of kites would have required coordinated work from multiple people and are thus indicative of social organization, even if the trapping of animals is a comparatively simple hunting technique. The use of kites in trapping animals is depicted in Israeli, Mongolian and Sinai petroglyphs; these drawings may not always be contemporaneous to the actual usage of the kites. Petroglyphs relating to kites have been found on kites.
Studies show that even low walls or linear structures like pipelines can effectively "guide" animals, which do not attempt to cross the lines even if they are physically able to do so, explaining the effectiveness of desert kites. The low visibility of the kite structures prevents the animals from recognizing the trap. The positioning of pits at the end of convergent enclosures and the presence of small walls delimitating pits from the enclosure would hide the pit from the animals until they are too close to change course in their panic. The entrances often are situated opposite to the direction of animal migration in the region on a wide scale, or of daily animal behaviours on a small scale. The use of desert kites may have had a significant impact on wild animals.
Research history
The usage of kite-like structures to trap animals is attested in 1831. Desert kites were originally identified in aerial images during the 1920s and were initially interpreted as animal traps, enclosures for domesticated animals or fortresses. They are referred to as "desert kites" or "kites", a name bestowed to them by the Royal Air Force pilot Group Captain Lionel Rees, in reference to their resemblance to toy kites. Given that they are commonly found in desert areas, they later became known as "desert kites", which is now the commonly used term in academic literature.
The advent of publicly available satellite imagery such as Google Earth and Google Maps during the 2010s, on which desert kites are visible to everyone, has led to a resurgence of interest in these archaeological sites and the realization that they are widespread. However, without fieldwork, it is difficult to gain a full picture of what they were. Only a very few kites have been excavated or subject to dating efforts, and many of these are not representative of the majority of kites.
Engraved depictions of the layout of desert kites have been found, some of which are schematic and others are like scaled models. Open questions in kite research include what they were used for, when they were used and why the technology is so widespread.
See also
Buffalo jump
Fishing weir
Game drive system
Hartashen Megalithic Avenue
Jawa, Jordan
Mustatil, similar formations in Arabia
Petroform
References
Sources
External links
Globalkites, worldwide database of kites
Archaeological terminology
History of hunting
Hunting methods
Open problems
Types of wall | Desert kite | [
"Engineering"
] | 1,620 | [
"Structural engineering",
"Types of wall"
] |
70,502,530 | https://en.wikipedia.org/wiki/Kinematics%20of%20the%20cuboctahedron | The skeleton of a cuboctahedron, considering its edges as rigid beams connected at flexible joints at its vertices but omitting its faces, does not have structural rigidity. Consequently, its vertices can be repositioned by folding (changing the dihedral angle) at the edges and face diagonals. The cuboctahedron's kinematics is noteworthy in that its vertices can be repositioned to the vertex positions of the regular icosahedron, the Jessen's icosahedron, and the regular octahedron, in accordance with the pyritohedral symmetry of the icosahedron.
Rigid and kinematic cuboctahedra
When interpreted as a framework of rigid flat faces, connected along the edges by hinges, the cuboctahedron is a rigid structure, as are all convex polyhedra, by Cauchy's theorem. However, when the faces are removed, leaving only rigid edges connected by flexible joints at the vertices, the result is not a rigid system (unlike polyhedra whose faces are all triangles, to which Cauchy's theorem applies despite the missing faces).
Adding a central vertex, connected by rigid edges to all the other vertices, subdivides the cuboctahedron into square pyramids and regular tetrahedra, meeting at the central vertex. Unlike the cuboctahedron itself, the resulting system of edges and joints is rigid, and forms the vertex figure of the infinite tetrahedral-octahedral honeycomb.
Cyclical cuboctahedron transformations
The cuboctahedron can be transformed cyclically through four polyhedra, repeating the cycle endlessly. Topologically, the transformation follows a Möbius loop: it is an orientable double cover of the octahedron. Physically, it is a spinor.
In their spatial relationships the cuboctahedron, icosahedron, Jessen's icosahedron, and octahedron nest like Russian dolls and are related by a helical contraction. The contraction begins with the square faces of the cuboctahedron folding inward along their diagonals to form pairs of triangles. The 12 vertices of the cuboctahedron spiral inward (toward the center) and move closer together until they reach the points where they form a regular icosahedron; they move slightly closer together until they form a Jessen's icosahedron; and they continue to spiral toward each other until they coincide in pairs as the 6 vertices of the octahedron.
The general cuboctahedron transformation can be parameterized along a continuum of special-case transformations with two limit cases: one in which the edges of the cuboctahedron are rigid, and one in which they are elastic.
Rigid-edge transformation
The rigid-edge cuboctahedron transformation symmetrically transforms the cuboctahedron into a regular icosahedron, a Jessen's icosahedron, and a regular octahedron, in the sense that the polyhedron's vertices take on the vertex positions of those polyhedra successively.
The cuboctahedron does not actually become those other polyhedra, and they cannot transform into each other (if they have rigid edges), because unlike the cuboctahedron they do have structural rigidity as a consequence of having only triangular faces.
What the cuboctahedron with rigid edges actually can transform into (and through) is a regular icosahedron from which 6 edges are missing (a pseudoicosahedron), a Jessen's icosahedron in which the 6 reflex edges are missing or elastic, and a double cover of the octahedron that has two coincident rigid edges connecting each pair of vertices (formed by making pairs of cuboctahedron vertices coincide).
Elastic-edge transformation
There is a tensegrity polyhedron that embodies and enforces the closely related elastic-edge cuboctahedron transformation. The tensegrity icosahedron has a dynamic structural rigidity called infinitesimal mobility and can only be deformed into symmetrical polyhedra along that spectrum from cuboctahedron to octahedron. It is called the tensegrity icosahedron because its median stable form is Jessen's icosahedron.
Although the transformation is described above as a contraction of the cuboctahedron, the stable equilibrium point of the tensegrity is Jessen's icosahedron; the tensegrity icosahedron resists being deformed from that shape and can only be forced to expand or contract from it to the extent that its edges are elastic (able to lengthen under tension). Forcing the polyhedron away from its stable resting shape (in either direction) involves stretching its 24 short edges slightly and equally. Force applied to any pair of parallel long edges, to move them closer together or farther apart, is transferred automatically to stretch all the short edges uniformly, shrinking the polyhedron from its medium-sized Jessen's icosahedron toward the smaller octahedron, or expanding it toward the larger regular icosahedron and still larger cuboctahedron, respectively. Releasing the force causes the polyhedron to spring back to its Jessen's icosahedron resting shape.
In the elastic-edge transformation the cuboctahedron edges are not rigid (though Jessen's icosahedron's 6 long edges are). What the cuboctahedron transforms into is a regular icosahedron of shorter radius and shorter edge length, a Jessen's icosahedron of still shorter radius and (minimum) edge length, and finally an octahedron of still shorter radius but the same (maximum) edge length as the cuboctahedron (but only after the edges have shortened and lengthened again, and come together in coincident pairs).
Duality of the rigid-edge and elastic-edge transformations
The rigid-edge and elastic-edge cuboctahedron transformations differ only in having reciprocal parameters: in the elastic-edge transformation the Jessen's icosahedron's short edges stretch and its long edges are rigid, and in the rigid-edge transformation its long edges compress and its short edges are rigid. Everything in the descriptions above except the metrics applies to all cuboctahedron transformations. In particular, the vertices always move in helices toward the center as the cuboctahedron transforms into the octahedron, and Jessen's icosahedron (with 90° dihedral angles and three invariant orthogonal planes) is always the median point, stable to the extent that there is resistance to stretching or compressing.
The elastic-edge cuboctahedron transformation is usually given as the mathematics of the tensegrity icosahedron because it comes closest to modeling how most actual tensegrity icosahedron structures behave. However, one could certainly construct a tensegrity icosahedron in which the short edges (cables) were perfectly inelastic, and the long edges (struts) were compressible springs. Such a tensegrity would perform the rigid-edge cuboctahedron transformation.
Finally, both transformations are pure abstractions, the two limit cases of an infinite family of cuboctahedron transformations in which there are two elasticity parameters and no requirement that one of them be 0. Neither limit case is apt to apply perfectly to most real tensegrity structures, which usually have some elasticity in both the cables and the struts, giving their actual behavior metrics that are non-trivial to calculate. In engineering practice, only a tiny amount of elasticity is required to allow a significant degree of motion, so most tensegrity structures are constructed to be "drum-tight" using nearly inelastic struts and cables. A tensegrity icosahedron transformation is a kinematic cuboctahedron transformation with reciprocal small elasticity parameters.
Jitterbug transformations
The twisting, expansive-contractive transformations between these polyhedra were named Jitterbug transformations by Buckminster Fuller. Fuller did not give any mathematics; like many great geometers before him (Alicia Boole Stott for example) he did not have any mathematics to give. But he was the first to stress the importance of the cuboctahedron's radial equilateral symmetry which he applied structurally (and patented) as the octet truss, intuiting that it plays a fundamental role not only in structural integrity but in the dimensional relationships between polytopes. He discovered the symmetry transformations of the cuboctahedron, understood their relationship to the tensegrity icosahedron, and even gave demonstrations of the rigid-edge cuboctahedron transformation before audiences (in the days before computer-rendered animations). His demonstration with commentary of the "vector equilibrium", as he called the cuboctahedron, is still far more illuminating than the animations in this article.
Notes
References
Bibliography
; see the video itself at "The Borromean Rings: A new logo for the IMU", International Mathematical Union
External links
Archimedean solids
Quasiregular polyhedra
Tensile architecture | Kinematics of the cuboctahedron | [
"Technology"
] | 1,867 | [
"Structural system",
"Tensile architecture"
] |
70,504,377 | https://en.wikipedia.org/wiki/Lydia%20W.%20S.%20Finley | Lydia W. S. Finley is an American scientist and an assistant member at the Cell Biology Program at Memorial Sloan Kettering Cancer Center and an assistant professor at Weill Cornell Medical College. Finley is known for her contributions to understanding the metabolic underpinnings of stem cell fate.
Biography
Finley received her Bachelor of Science (BS) degree summa cum laude from Yale University. Finley completed her PhD at Harvard Medical School, where she worked in the laboratory of Marcia Haigis. Finley then worked as a postdoctoral fellow in the laboratory of Craig Thompson at Memorial Sloan Kettering Cancer Center. After completing her postdoctoral work, Finley opened her own laboratory in 2017, which is located in the Memorial Sloan Kettering Cancer Center.
Finley has received various awards for her work. These include the Dale F. Frey Award for Breakthrough Scientists from the Damon Runyon Cancer Research Foundation and the Searle Scholars Award. Finley currently serves as an associate editor for Cancer & Metabolism and a reviewing editor at eLife. As of April 2022, Finley has authored over 40 publications and has an h-index of 30.
Scientific contributions
Finley's research has focused on interrogating the connections between metabolites and their role in regulating embryonic stem cell self-renewal and cell fate decisions. Notably, as a postdoctoral fellow, Finley and Bryce W. Carey discovered that intracellular α-ketoglutarate levels regulated chromatin and gene expression, and contributes to embryonic stem cell renewal. In 2022, Finley and co-authors published a paper describing a non-canonical arm of the TCA cycle.
Selected awards and honors
National Science Foundation Graduate Research Fellowship
Dale F. Frey Award for Breakthrough Scientists, Damon Runyon Cancer Research Foundation
2018: Searle Scholar
2020: Pershing Square Sohn Cancer Research Alliance Award
Selected publications
Carey BW*, Finley LW*, Cross JR, Allis CD, Thompson CB. Intracellular α-ketoglutarate maintains the pluripotency of embryonic stem cells. Nature. 2015;518(7539):413-416. doi:10.1038/nature13981
Arnold PK, Jackson BT, Paras KI, Brunner JS, Hart ML, Newsom OJ, Alibeckoff SP, Endress J, Drill E, Sullivan LB, Finley LWS. A non-canonical tricarboxylic acid cycle underlies cellular identity. Nature. 2022 Mar;603(7901):477-481. doi: 10.1038/s41586-022-04475-w. Epub 2022 Mar 9. PMID 35264789; PMCID: PMC8934290.
References
21st-century American biologists
Yale University alumni
Harvard Medical School alumni
American editors
Year of birth missing (living people)
Living people
American cell biologists
Memorial Sloan Kettering Cancer Center faculty
Weill Medical College of Cornell University faculty
American women biologists
21st-century American women scientists
Stem cell researchers | Lydia W. S. Finley | [
"Biology"
] | 617 | [
"Stem cell researchers",
"Stem cell research"
] |
70,504,654 | https://en.wikipedia.org/wiki/FluBot | FluBot is a sophisticated SMS computer virus –specifically a banking Trojan– of global reach which aims to steal private data from Android smart phones. Unlike much malware, FluBot has proven exceptionally durable, coming in waves or "campaigns" with each redesign. It masquerades as innocuous messages such as missed calls and deliveries, asking the receiver to click links that download spyware. A variant, TeaBot, has infiltrated official app stores, including Google Play Store, in the guise of a QR-code reader.
16,000 reports of FluBot were reported to the Australian Competition & Consumer Commission's Scamwatch in Australia across eight weeks in 2021. Although coverage of FluBot primarily centres on Australia and New Zealand, the scam has also targeted European countries such as Germany and Poland in 2022 campaigns.
In May 2022, FluBot infrastructure was taken down in an operation involving 11 countries and it is not expected to resurge.
References
Virus
Internet security
Deception
Security breaches
Types of malware
Android (operating system) malware | FluBot | [
"Technology"
] | 216 | [
"Computer security exploits"
] |
70,505,581 | https://en.wikipedia.org/wiki/Song%20Lin%20%28chemist%29 | Song Lin is a Chinese-American organic electrochemist who is a Tisch University Professor at Cornell University. His research involves the development of new synthetic organic methodologies that utilize electrochemistry to forge new chemical bonds. He is an Associate Editor of the journal Organic Letters, and serves on the Early Career Advisory Board of Chemistry - A European Journal. He was named by Chemical & Engineering News as one of their Trailblazers of 2022, a feature highlighting LGBTQ+ chemists in academia.
Early life and education
Lin was born in Tianjin. He became interested in science as a child, doing simple household experiments, and was supported by his high school chemistry teacher to pursue a career in research. He completed his bachelor's degree in chemistry at Peking University where he worked under the supervision of Zhangjie Shi. Lin moved to the United States for graduate studies and joined the organic chemistry department at Harvard University for doctoral research, where he researched small molecule asymmetric catalysis with Eric Jacobsen.
Research and career
Lin moved to the University of California, Berkeley for his postdoctoral research, where he worked in the lab of Christopher Chang. While studying electrocatalysis in Chang's lab, he became aware of the use of porous materials like covalent organic frameworks (COFs) to absorb carbon dioxide. In collaboration with the Yaghi group, Lin showed that porphyrin-containing COFs could catalyze the electrocatalytic reduction of CO2 to CO under applied current and in an aqueous environment.
Lin began his independent career at Cornell University where his group's research has focused on the identification of novel synthetic pathways for medicinally relevant compounds. He focuses on the use of electrochemistry to drive chemical reactions. Electrochemistry can make organic synthesis cheaper and more environmentally friendly. For example, Lin demonstrated an electrochemical approach to synthesize 1,2-diamines from alkenes, which are useful precursors to bioactive natural products, therapeutic agents, and molecular catalysts. More recently, Lin's group has developed a method to directly couple alkyl halides using electrochemistry, providing a promising approach towards this difficult chemical transformation.
Awards and honors
2017 Thieme Chemistry Journal Award
2018 National Science Foundation CAREER Award
2019 MIT Technology Review Innovators Under 35
2019 Alfred P. Sloan Foundation Fellowship
2019 Office of Naval Research Young Investigator
2020 Princeton University Bristol-Myers Squibb Lectureship
2020 Research Corporation Cottrell Scholar Award
2021 American Chemical Society National Fresenius Award
2021 Camille Dreyfus Teacher-Scholar Award
2021 FMC New Investigator Award
Selected publications
References
Peking University alumni
Harvard University alumni
Cornell University faculty
Electrochemists
Chinese emigrants to the United States
Living people
Year of birth missing (living people) | Song Lin (chemist) | [
"Chemistry"
] | 559 | [
"Electrochemistry",
"Electrochemists"
] |
56,303,072 | https://en.wikipedia.org/wiki/2-Naphthalenethiol | 2-Naphthalenethiol is an organosulfur compound with the formula C10H7SH. It is a white solid. It is one of two monothiols of naphthalene, the other being 1-naphthalenethiol.
Synthesis and reactions
2-Naphthalenethiol is prepared from 2-naphthol by the Newman–Kwart rearrangement starting from a thiocarbamate. It undergoes lithiation at the 1 and 3-position.
It can be used as a flavouring agent and has been described as having an “artichoke”, “meaty” and “creamy” taste”.
References
Thiols
2-Naphthyl compounds | 2-Naphthalenethiol | [
"Chemistry"
] | 151 | [
"Organic compounds",
"Thiols"
] |
56,303,583 | https://en.wikipedia.org/wiki/Great%20Replacement%20conspiracy%20theory | The Great Replacement (), also known as replacement theory or great replacement theory, is a debunked white nationalist far-right conspiracy theory espoused by French author Renaud Camus. The original theory states that, with the complicity or cooperation of "replacist" elites, the ethnic French and white European populations at large are being demographically and culturally replaced by non-white peoples—especially from Muslim-majority countries—through mass migration, demographic growth and a drop in the birth rate of white Europeans. Since then, similar claims have been advanced in other national contexts, notably in the United States. Mainstream scholars have dismissed these claims of a conspiracy of "replacist" elites as rooted in a misunderstanding of demographic statistics and premised upon an unscientific, racist worldview.
While similar themes have characterized various far-right theories since the late 19th century, the particular term was popularized by Camus in his 2011 book Le Grand Remplacement. The book associates the presence of Muslims in France with danger and destruction of French culture and civilization. Camus and other conspiracy theorists attribute recent demographic changes in Europe to intentional policies advanced by global and liberal elites (the "replacists") from within the Government of France, the European Union, or the United Nations; they describe it as a "genocide by substitution".
The conspiracy theory found support in Europe, and has also grown popular among anti-migrant and white nationalist movements from other parts of the West; many of their adherents maintain that "immigrants [are] flocking to predominantly white countries for the precise purpose of rendering the white population a minority within their own land or even causing the extinction of the native population". It aligns with (and is a part of) the larger white genocide conspiracy theory except in the substitution of antisemitic canards with Islamophobia. This substitution, along with a use of simple catch-all slogans, has been cited as one of the reasons for its broader appeal in a pan-European context, although the concept remains rooted in antisemitism in many white nationalist movements, especially (but not exclusively) in the United States.
Although Camus has publicly condemned white nationalist violence, scholars have argued that calls to violence are implicit in his depiction of non-white migrants as an existential threat to white populations. Several far-right terrorists, including the perpetrators of the 2019 Christchurch mosque shootings, the 2019 El Paso shooting, the 2022 Buffalo shooting and the 2023 Jacksonville shooting, have made reference to the "Great Replacement" conspiracy theory. American conservative media personalities, including Tucker Carlson and Laura Ingraham, have espoused ideas of a replacement. Some Republican politicians have endorsed the theory in order to appeal to far-right members of the Republican Party and as a way of signalling their loyalty to Donald Trump.
Background
Renaud Camus developed his conspiracy theory in two books published in 2010 and 2011, in the context of an increase in anti-immigrant rhetoric in public discourse during the previous decade. Europe also experienced an escalation in Islamic terrorist attacks during the 2000s–2010s, and a migrant crisis in the years 2015–2016, which exacerbated tensions and prepared public opinion for the reception of Camus's conspiracy theory. As the latter depicts a population replacement said to occur in a short time lapse of one or two generations, the migrant crisis was particularly conducive to the spread of Camus's ideas while the terrorist attacks accelerated the construction of immigrants as an existential threat among those who shared such a worldview.
Camus's theme of a future demise of European culture and civilization also parallels a "cultural pessimistic" and anti-Islam trend among European intellectuals of the period, illustrated in several best-selling and straightforwardly titled books released during the 2010s: Thilo Sarrazin's Germany Abolishes Itself (2010), Éric Zemmour's The French Suicide (2014) or Michel Houellebecq's Submission (2015).
Concept of Renaud Camus
The "Great Replacement" conspiracy theory was developed by French author Renaud Camus, initially in a 2010 book titled L'Abécédaire de l'in-nocence ("Abecedarium of no-harm"), and the following year in an eponymous book, Le Grand Remplacement (introduction au remplacisme global). Camus has claimed that the name "came to [him], almost by chance, perhaps in a more or less unconscious reference to the Grand Dérangement of the Acadians in the 18th century." As an epigraph to the later book, Camus chose Bertolt Brecht's quip from the satirical poem Die Lösung that the easiest thing to do for a government which had lost the confidence of its people would be to choose new people.
According to Camus, the "Great Replacement" has been nourished by "industrialisation", "despiritualisation" and "deculturation"; the materialistic society and globalism having created a "replaceable human, without any national, ethnic, or cultural specificity", what he labels "global replacism". Camus claims that "the great replacement does not need a definition," as the term is not, in his views, a "concept" but rather a "phenomenon".
In Camus's theory, the indigenous French people ("the replaced") is described as being demographically replaced by non-white populations ("the replacing [peoples]")—mainly coming from Africa or the Middle East—in a process of "peopling immigration" encouraged by a "replacist power".
Camus frequently uses terms and concepts related to the period of Nazi-occupied France (1940–1945). He for instance labels "colonizers" or "Occupiers" people of non-European descent who reside in Europe, and dismisses what he calls the "replacist elites" as "collaborationist". In 2017 Camus founded an organization named the National Council of European Resistance, in a self-evident reference to the World War II National Council of the Resistance (1943–1945). This analogy to the French Resistance against Nazism has been described as an implicit call to hatred, direct action or even violence against what Camus labels the "Occupiers; i.e. the immigrants". Camus has also compared the Great Replacement and the so-called "genocide by substitution" of the European peoples to the Holocaust.
Claimed influences
Camus cites two influential figures in the epilogue of his 2011 book The Great Replacement: British politician Enoch Powell's apocalyptic vision of future race relations—expressed in his 1968 "Rivers of Blood" speech—and French author Jean Raspail's depiction of the collapse of the West from an overwhelming "tidal wave" of Third World immigration, featured in his 1973 novel The Camp of the Saints.
Camus also declared to The Spectator magazine in 2016 that a key to understanding the "Great Replacement" can be found in his 2002 book Du Sens. In the latter he wrote that the words "France" and "French" equal a natural and physical reality rather than a legal one, in a cratylism similar to Charles Maurras's distinction between the "legal" and the "real country". During the same interview, Camus mentioned that he began to imagine his conspiracy theory back in 1996, during the redaction of a guidebook on the department of Hérault, in the South of France: "I suddenly realized that in very old villages [...] the population had totally changed too [...] this is when I began to write like that."
Similar themes
White genocide conspiracy theory
Despite its own singularities and concepts, the "Great Replacement" is encompassed in a larger and older "white genocide" conspiracy theory, popularized in the US by neo-Nazi David Lane in his 1995 White Genocide Manifesto, where he asserted that governments in Western countries were intending to turn white people into "extinct species". Scholars generally agree that, although he did not father the theme, Camus indeed coined the term "Great Replacement" as a slogan and concept, and eventually led it to its fame in the 2010s.
The idea of "replacement" under the guidance of a hostile elite can be further traced back to pre-WWII antisemitic conspiracy theories which posited the existence of a Jewish plot to destroy Europe through miscegenation, especially in Édouard Drumont's antisemitic bestseller La France juive (1886). Commenting on this resemblance, historian Nicolas Lebourg and political scientist Jean-Yves Camus suggest that Renaud Camus's contribution was to replace the antisemitic elements with a clash of civilizations between Muslims and Europeans. Also in the late 19th century, imperialist politicians invoked the Péril jaune (Yellow Peril) in their negative comparisons of France's low birth-rate and the high birth-rates of Asian countries. From that claim arose an artificial, cultural fear that immigrant-worker Asians soon would "flood" France. This danger supposedly could be successfully countered only by increased fecundity of French women. Then, France would possess enough soldiers to thwart the eventual flood of immigrants from Asia. Maurice Barrès's nationalist writings of that period have also been noted in the ideological genealogy of the "Great Replacement", Barrès contending both in 1889 and in 1900 that a replacement of the native population under the combined effect of immigration and a decline in the birth rate was happening in France.
Scholars also highlight a modern similarity to European neo-fascist and neo-Nazi thinkers from the immediate post-war, especially Maurice Bardèche, René Binet and Gaston-Armand Amaudruz, and to concepts advanced from the 1960s onward by the French Nouvelle Droite. The associated and more recent conspiracy theory of "Eurabia", published by British author Bat Ye'or in her 2005 eponymous book, is often cited as a probable inspiration for Camus's "Great Replacement". Eurabia theory likewise involves globalist entities, that are led by both French and Arab powers, conspiring to Islamize Europe, with Muslims submerging the continent through immigration and higher birth rates. The conspiracy theory also depicts immigrants as invaders or as a fifth column, invited to the continent by a corrupt political elite.
Analysis
Demographic statistics
While the ethnic demography of France has shifted as a result of post-WWII immigration, scholars have generally dismissed the claims of a "great replacement" as being rooted in an exaggeration of immigration statistics and unscientific, racially prejudiced views. Geographer Landis MacKellar criticized Camus's thesis for assuming "that third- and fourth- generation 'immigrants' are somehow not French." Researchers have variously estimated the Muslim population of France at between 8.8% and 12.5% in 2017, and less than 1% in 2001, making a "replacement" unlikely according to MacKellar.
Racial connotations
In the words of scholar Andrew Fergus Wilson, whereas the islamophobic Great Replacement theory can be distinguished from the parallel antisemitic white genocide conspiracy theory, "they share the same terms of reference and both are ideologically aligned with the so-called '14 words' of David Lane ["We must secure the existence of our people and a future for white children"]." In 2021, the Anti-Defamation League wrote that "since many white supremacists, particularly those in the United States, blame Jews for non-white immigration to the U.S.", the Great Replacement theory has been increasingly associated with antisemitism and conflated with the white genocide conspiracy theory. Scholar Kathleen Belew has argued that the Great Replacement theory "allows an opportunism in selecting enemies", but "also follows the central motivating logic, which is to protect the thing on the inside [i.e. the preservation and birth rate of the white race], regardless of the enemy on the outside."
According to Australian historian A. Dirk Moses, the great replacement theory is a form of psychological projection in which Europeans—who enacted settler-colonial projects entailing the elimination and replacement of native populations by settler societies—fear the reverse may happen to them.
In German discourse, Austrian political scientist Rainer Bauböck questioned the conspiracy theorists' use of the terms "population replacement" or "exchange" (). Using Ruth Wodak's analysis that the slogan needs to be viewed in its historical context, Bauböck has concluded that the conspiracy theory is a reemergence of the Nazi ideology of ("ethnicity inversion").
Popularity
The simplicity and use of catch-all slogans in Camus's formulations—"you have one people, and in the space of a generation you have a different people"—as well as his removal of antisemitism from the original neo-Nazi "white genocide" conspiracy theory, have been cited as conducive to the popularity of the "Great Replacement" in Europe.
In a survey led by Ifop in December 2018, 25% of the French subscribed to the conspiracy theory; as well as 46% of the responders who defined themselves as "Gilets Jaunes" (Yellow Vest protesters). In another survey led by Harris Interactive in October 2021, 61% of the French believed that the "Great Replacement" will happen in France; 67% of the respondents were worried about it.
The theory has also become influential in far-right and white nationalist circles outside of France. The conspiracy theory has been cited by Canadian far-right political activist Lauren Southern in a YouTube video of the same name released in July 2017. Southern's video had attracted in 2020 more than 686,000 views and is credited with helping to popularize the conspiracy theory. Counter-jihad Norwegian blogger Fjordman has also participated in spreading the theory. It has also been promoted by the German edition of The Epoch Times, a far-right Falun Gong-associated newspaper.
Prominent right-wing extremist websites such as Gates of Vienna, Politically Incorrect, and have provided a platform for bloggers to diffuse and popularize the theory of the "Great Replacement". Among its main promoters are also a wide-ranging network of loosely connected white nationalist movements, especially the Identitarian movement in Europe, and other groups like PEGIDA in Germany.
Political influence
Europe
France
Much of the European spread of the Great Replacement () conspiracy theory rhetoric is due to its prevalence in French national discourse and media. Nationalist right-wing groups in France have asserted that there is an ongoing "Islamo-substitution" of the indigenous French population, associating the presence of Muslims in France with potential danger and destruction of French culture and civilization.
In 2011, Marine Le Pen evoked the theory, claiming that France's "adversaries" were waging a moral and economic war on the country, apparently "to deliver it to submersion by an organized replacement of our population". In 2013, historian Dominique Venner's suicide in Notre-Dame de Paris, in which he left a note outlining the "crime of the replacement of our people" is reported to have inspired the far-right Iliade Institute main ideological tenet of the Great Replacement. Referring to the conspiracy theory, Marine Le Pen publicly praised Venner, claiming that his "last gesture, eminently political, was to try to awaken the French people".
In 2015, Guillaume Faye gave a speech at the Swedish Army Museum in Stockholm, in which he claimed there were three societal things being used against Europeans to carry out a supposed Great Replacement: abortion, homosexuality and immigration. He asserted that Muslims were replacing white people by using birthrates as a demographic weapon.
In June 2017, a BuzzFeed News investigation revealed three National Front candidates subscribing to the conspiracy theory ahead of the legislative elections. These included Senator Stéphane Ravier's personal assistant, who claimed the Great Replacement had already started in France. Publishing an image of blonde girl next to the caption "Say no to white genocide", Ravier's aide politically charged the concept further, writing "the National Front or the invasion".
By September 2018, in a meeting at Fréjus, Marine Le Pen closely echoed Great Replacement rhetoric. Speaking of France, she declared that "never in the history of mankind, have we seen a society that organizes an irreversible submersion" that would eventually cause French society to "disappear by dilution or substitution, its culture and way of life". Following the Christchurch mosque shootings, Le Pen falsely denied knowledge of the theory.
Former National Assembly delegate Marion Maréchal, who is a junior member of the political Le Pen family, is also a proponent of the theory. In March 2019, in a trip to the U.S., Maréchal evoked the theory, stating "I don't want France to become a land of Islam". Insisting that the Great Replacement was "not absurd", she declared the "indigenous French" people, apparently in danger of being a minority by 2040, now wanted their "country back".
National Rally's serving president Marine Le Pen, who is the aunt of Maréchal, has been heavily influenced by the Great Replacement. The Frankfurter Allgemeine Zeitung has described the conspiracy theory creator Renaud Camus as Le Pen's "whisperer". In May 2019, National Rally spokesman Jordan Bardella was reported to use the conspiracy theory during a televised debate with Nathalie Loiseau, after he argued that France must "turn off the tap" from the demographic bomb of African immigration into the country.
In June 2019, journalist and author Éric Zemmour pushed the concept in comparison to the Kosovo War, claiming "In 1900, there were 90% Serbs and 10% Muslims in Kosovo, in 1990 there were 90% Muslims and 10% Serbs, then there was war and the independence of Kosovo". Zemmour, author of The French Suicide, has repeatedly described "the progressive replacement, over a few decades, of the historic population of our country by immigrants, the vast majority of them non-European". Later that month, Marion Maréchal joined Zemmour in invoking the Great Replacement in relation to the Balkan region, stating "I do not want my France to become Kosovo" and declared that the changing demographics of France "threatens us" ("nous menace") and that this was increasingly clear. Zemmour ran for president in 2022 and continued to extensively promote the theory during his campaign. He finished in fourth place in the first round of the election, taking 7,07% of the vote.
Austria
Identitäre Bewegung Österreich (IBÖ), the Austrian branch of the Identitarian movement, promotes this theory, citing a "great exchange" or replacement of the population that supposedly needs to be reversed. In April 2019, Heinz-Christian Strache campaigning for his FPÖ party ahead of the 2019 European Parliament election endorsed the conspiracy theory. Claiming that "population replacement" in Austria was a real threat, he stated that "We don't want to become a minority in our own country". Compatriot Martin Sellner, who also supports the theory, celebrated Strache's political use of the Great Replacement.
Belgium
In September 2018, , an extremist Flemish youth organization, were reported to be endorsing the conspiracy theory. The group, claiming that native populations of Europe were being replaced by migrants; they proposed an end to all immigration, forced deportation of non-whites, and the founding of ethnostates. The following month, VRT detailed how the organization was discussing the Great Replacement on secretive chat channels, and using the conspiracy theory to promote Flemish ethnic identity.
In March 2019, Flemish nationalist Dries Van Langenhove of the Vlaams Belang party repeatedly stated that the Flemish people were "being replaced" in Belgium, posting claims on social media which endorsed the Great Replacement theory.
Denmark
Use of the Great Replacement () conspiracy theory has become common in right-wing Danish political rhetoric. In April 2019, Rasmus Paludan, leader of the Hard Line party, which is widely associated with the Great Replacement, claimed that by the year 2040 ethnic Danish people would be approaching to be a minority in Denmark, having been outnumbered by Muslims and their descendants. During a debate for the 2019 European Parliament elections, Paludan used the concept to justify a proposal to ban Muslim immigration and deport all Islamic residents from the country, in what Le Monde described as Paludan "preaching the 'great replacement theory.
In June 2019, Pia Kjærsgaard (Danish People's Party) invoked the conspiracy theory while serving as Speaker of the Danish Parliament. After the alleged encouragement of Muslim communities to "vote red", for the Social Democrats; Kjærsgaard asked "What will happen? A replacement of the Danish people?".
Finland
Far-right Finns Party representatives and ministers have used the word "great replacement" () in their writings. Finns Party Speaker of the Parliament Jussi Halla-Aho and the party leader and deputy Prime Minister Riikka Purra have also promoted the theory. Halla-aho stated that it is ”dishonest to say that the great replacement is not going on, that it would not be rapid, and that it would not continue just as long as it is allowed to continue.” Riikka Purra wrote ”In any case, I use the term great replacement myself, because that is what this is, as long as this is being actively perpetrated”, Purra wrote. "As long as immigration policy is active and promotes immigration, the Finnish population will be exchanged for another". In October 2023 four men were convicted of offences committed with terrorist intent. According to the prosecutor, the defendants were motivated by the idea of a conspiracy of the government and Jewish people to replace the native population. Police said the potential targets of the attack were political decision-makers.
Germany
Ex-SPD politician Thilo Sarrazin is reported to be one of the most influential promoters of the Great Replacement, having published several books on the subject, some of which, such as Germany Abolishes Itself, are in high circulation. Sarrazin has proposed that there are too many immigrants in Germany, and that they supposedly have lower IQs than Germans. Regarding the demographics of Germany, he has claimed that in a century ethnic Germans will drop in number to 25 million, in 200 years to eight million and in 300 years: three million.
In May 2016, Alternative for Germany (, AfD) deputy leader Beatrix von Storch used a language reminiscent of the theory when she claimed that plans for a mass exchange of populations ("Massenaustausch der Bevölkerung") had long been made.
In April 2017, a few months before he assumed the leadership of the AfD, Alexander Gauland released a press statement regarding the issue of family reunification for refugees, in which he claimed that "Population exchange in Germany is running at full speed". In October 2018, following Beatrix von Storch's lead, Bundestag member Petr Bystron said the Global Compact for Migration was part of the conspiracy to bring about systemic population change in Germany.
In March 2019, Vice Germany reported how AfD MP attempted to justify and assign blame for the Christchurch mosque shootings, in relation to his "The Great Exchange" theory, by asserting that the shooter's actions were driven by "overpopulation" from immigrants and "climate protection" against them. Laatsch also claimed that the climate movement, who he labelled "climate panic propagators", had a "shared responsibility" for the massacre, and singled out child activist Greta Thunberg.
Similarly, right-wing publicist denied that either Anders Behring Breivik's 2011 manifesto, which referred to the Eurabia variant of the "white genocide" narrative, or Brenton Tarrant's 2019 The Great Replacement manifesto, had any connection to the theory. Claiming that it was, in fact, not a conspiracy theory at all, Lichtmesz said both Breivik and Tarrant were reacting to a real phenomenon; a "historically unique experiment" of a "Great Exchange" of people.
Hungary
Prime Minister Viktor Orbán and his political party Fidesz in Hungary have been associated with the conspiracy theory over the course of several years. The Sydney Morning Herald detailed Orbán's belief in and promotion of the Great Replacement as being central to the modern right-wing politics of Europe. In December 2018, he claimed the "Christian identity of Europe" needed saving, and labelled refugees traveling to Europe as "Muslim invaders". In a speech, Orbán asserted: "If in the future Europe is to be populated by people other than Europeans, and we accept this as a fact and see it as natural, then we will effectively be consenting to population replacement: to a process in which the European population is replaced".
He has also stated: "In all of Europe there are fewer and fewer children, and the answer of the West is migration," concluding that "We Hungarians have a different way of thinking. Instead of just numbers, we want Hungarian children." ThinkProgress described the comments as pushing a version of the theory. In April 2019, Radio New Zealand published insight that Orban's plans to cut taxes for large Hungarian families could be linked with fears of the Great Replacement.
Ireland
A 2019 Lidl advertisement that featured a white Irish woman, her Afro-Brazilian partner and their mixed race son was targeted by former journalist Gemma O'Doherty as part of an attempt at a "Great Replacement". After facing online harassment the family decided to leave Ireland. The "Great Replacement" has also been used in Ireland in opposition to direct provision centres, used to house asylum seekers.
Writing in 2020, Richard Downes said that "Rather than seeing the increase in non-Irish people living and making their lives here as being a normal part of a modern European country, some of the new nationalists see it as a conspiracy to overwhelm Ireland with foreigners. For many of them the conspirators include the Irish government, NGOs, the EU and the UN. They believe that these organisations want to replace Irish people with brown and black people from abroad."
The term "great replacement" was also used when the RTÉ News featured the three first babies born in 2020, born to Polish, Black and Indian mothers; journalist Fergus Finlay saying "I don't care about the vulgar abuse, but I really do believe that these hatemongers should be prosecuted when they incite others to hatred and violence against people whose only crime is their skin colour or religion. I find it hard to understand why the State hasn't acted already against these cruel ideologues who think they can say whatever they like under the banner of free speech. They may be small in number now, and on the surface they may just seem bonkers, but we've been here before. Political movements have been built on hatred of the other, and we know the damage they have caused."
Garda Commissioner (national chief of police) Drew Harris spoke about far right groups in 2020, saying that "Irish groups [believing] in the great replacement theory" had plans "to disrupt key State institutions and infrastructure. This included Dublin Port, high profile shopping areas such as Grafton Street in Dublin, Dáil Éireann and Government departments."
Some participants in the 2022–2023 Irish anti-immigration protests such as Hermann Kelly and Derek Blighe support a Great Replacement theory, as well as referring to the influx of immigrants as an "invasion" and a "plantation".
In 2024, a Red C survey found that 22% believed the establishment is replacing white people with non-white immigrants and that elected officials wanted more immigration to bring in obedient voters. This is linked with the great replacement theory.
Italy
The current Italian Prime Minister Giorgia Meloni has endorsed the Great Replacement ideology. Deputy Prime Minister Matteo Salvini of Italy (2018–2019) has repeatedly adopted the theme of the Great Replacement. In May 2016, two years before his election to office, he claimed "ethnic replacement is underway" in Italy in an interview with Sky TG24. Accusing nameless, well-funded organizations for importing workers that he named "farm slaves", he stated that there was a "lucrative attempt at genocide" of Italians.
In April 2023, the Minister of Agriculture, Food Sovereignty and Forests Francesco Lollobrigida remarked to a trade union conference that "Italians are having fewer children, so we're replacing them with someone else. [We say] yes to helping births, no to ethnic replacement. That's not the way forward".
Netherlands
In April 2015, writing on the publishing website GeenStijl, scholar of Islam Hans Jansen used Great Replacement rhetoric, suggesting that it was an "undisputed" fact that among the European Union's governing elite there was a common consensus that Europeans were "no good and can be better replaced". In May 2015, Martin Bosma, a Dutch parliament Representative for the Party for Freedom (PVV), released his book . Invoking the conspiracy theory, Bosma wrote about a growing 'a new population' of immigrants which lent itself to an apparently 'post-racial Multicultural State of Salvation'.
In March 2017, Thierry Baudet, leader of the right wing Forum for Democracy (FvD) party, promoted the theory after he claimed that the country's so-called elite were deliberately "homeopathically diluting" the Dutch population, in a speech about "national self-hatred". He said there was a plot to racially mix the ethnic Dutch with "all the people of the world", so that there would "never be a Dutchman again".
In January 2018, PVV Representative Martin Bosma endorsed the Great Replacement theory, and one of its key propagators, after meeting with Renaud Camus at a PVV demonstration in Rotterdam and tweeting his support. Filip Dewinter, a leading member of the Flemish secessionist Vlaams Belang party, who had traveled to the Netherlands on the day of the protest to meet with Camus, named him as a "visionary man" to the media.
Party for Freedom politician Geert Wilders of the Netherlands supports the notion of a Great Replacement occurring in Europe. In October 2018, Wilders invoked the conspiracy theory, claiming the Netherlands was "being replaced with mass immigration from non-western Islamic countries" and Rotterdam being "the port of Eurabia". He claimed 77 million, mainly Islamic immigrants would attempt to enter Europe over the course of half a century, and that white Europeans would cease to exist unless they were stopped. In 2019, The New York Times reported how Camus's demographic-based alarmist theories help fuel Wilders and his Party for Freedom's nativist campaigning.
In September 2018, Dutch author Paul Scheffer analyzed the Great Replacement and its political developments, suggesting that Forum for Democracy and Party for Freedom were forming policy regarding the demography of the Netherlands through the lens of the conspiracy theory.
Spain
The far-right party Vox has been described as circulating the theory for its discourse about low natality rates in Spaniards compared to migrants. According to journalist Antonio Maestre of El Diario, such an ideology is shared between Vox and some extreme strains of Catalan nationalism who fear replacement by Spanish-speakers.
United Kingdom
According to November 2018 research from the University of Cambridge, 31% of Brexit voters believe in the conspiracy theory compared to 6% of British people who oppose Brexit.
In July 2019, left-wing English musician and activist Billy Bragg released a public statement which accused fellow singer-songwriter Morrissey of endorsing the theory. Bragg suggested "that Morrissey is helping to spread this idea—which inspired the Christchurch mosque murderer—is beyond doubt".
Prior to the 2024 United Kingdom general election, videos of non-white people in London with captions such as "This is not Iran" spread on social media. Hope not Hate researcher Patrik Hermansson described the videos as prime examples of dog whistles due to using language and imagery that direct viewers to the conspiracy theory without explicitly referencing it. He said, "[The videos] are dangerous because they often avoid moderation and appear acceptable by seeming neutral in how they present reality".
Turkey
Leader of the Victory Party Ümit Özdağ uses a Turkish version of the theory. He previously argued that Turkey will be a "Migrantland" () unless Kemal Kılıçdaroğlu wins the 2023 Turkish presidential election.
North America
Canada
YouTuber Lauren Southern of Canada has helped amplify the conspiracy theory. In 2017, Southern dedicated a video to the Great Replacement, gaining over half a million views on her channel, before it was deleted. 2018 mayoral candidate for Toronto Faith Goldy has publicly embraced the replacement theory. In 2019, in the aftermath of the Christchurch mosque shootings in Christchurch, New Zealand, Vice accused Goldy of routinely pushing the same ideas of birthrate declines and the population replacement of whites, found in the gunman's The Great Replacement manifesto. When white nationalist Paul Fromm co-opted the pre-1967 Canadian national flag, the Canadian Red Ensign, he referred to it as "the flag of the true Canada, the European Canada before the treasonous European replacement schemes brought in by the 1965 immigration policies".
In June 2019, columnist Lindsay Shepherd claimed that "whites are becoming a minority" in the West, describing her assertion as "population replacement". She was criticized by Canadian MP Colin Fraser at a House of Commons justice committee for not denouncing the concept, while Nathaniel Erskine-Smith accused Shepherd of openly embracing the conspiracy theory.
The political commentator Mathieu Bock-Côté is known to frequently amplify the Great Replacement theory (French: Grand Remplacement) into mainstream media with his political ideologies.
United States
The Great replacement in the United States is the American version of a white nationalist far-right conspiracy theory that racial minorities are displacing the traditional white American population and taking control of the nation. Versions of the theory "have become commonplace" in the Republican Party of the United States, and have become a major issue of political debate. It also has stimulated violent responses including mass murders. It resembles the Great Replacement theory promoted in Europe, but has its origins in American nativism around 1900. According to Erika Lee, in 1894 the old stock Yankee upper-class founders of the Immigration Restriction League were, "convinced that Anglo-Saxon traditions, peoples, and culture were being drowned in a flood of racially inferior foreigners from Southern and Eastern Europe."
A May 2022 poll by Yahoo! News and YouGov found that 61% of people who voted for Donald Trump in the 2020 U.S. presidential election believe that "a group of people in this country are trying to replace native-born Americans with immigrants and people of color who share their political views."
Oceania
Australia
The media in Australia have covered former Senator Fraser Anning of Queensland and his endorsement of the Great Replacement conspiracy theory. In April 2019, Reuters reported how Anning was amplifying replacement theory by suggesting that Muslims would "out-breed us very quickly". In May 2019, Anning alleged that white Australians would "fast become a minority" if they did not defend their "ethno-cultural identity".
New Zealand
The far right neo-Nazi youth group Action Zealandia has endorsed the Great Replacement theory, alleging that European identity in New Zealand is being threatened by economically driven non-white migration. In addition, the group has promoted the pseudohistorical notion that white people settled in New Zealand before the arrival of the indigenous Māori people. According to the journalist Marc Daalder, Action Zealandia is the successor to the Dominion Movement, a far right group that ceased its activities following the 2019 Christchurch mosque shootings.
Asia
India
Hindu nationalists in India have stoked fears of demographic erasure of Hindus by Muslims, alleging that Muslims have higher fertility rates compared to other Indian communities and forced religious conversions are reducing the number of Hindus. In 2022, Hindu nationalist Yati Narsinghanand was arrested on hate speech charges and spoke about the risk of a Muslim prime minister in 2029, which he said would lead to killings and forced conversions of Hindus. Members of India's parliament and Indian television channels have also mainstreamed the claim of a demographic threat to Hindus. India's former chief election commissioner, S.Y. Quraishi, said that fearmongering over the threat to a Hindu majority has increased since 2014.
Malaysia
Hard right conservatives in Malaysia have expressed fears that local Indian communities, often of Tamil descent, may oust Malay Muslims, who are the current majority in Malaysia. These fears were heightened due to the Sri Lankan Civil War, backlash against activities of the Hindu Rights Action Force, and Hindu nationalism in India. Political actors have exploited this to acquire votes in Malaysia's heartland and to rally opposition against ratifying the International Convention on the Elimination of All Forms of Racial Discrimination.
Africa
Tunisia
In February 2023, the President of Tunisia Kais Saied made comments about African immigration into Tunisia, saying that they were changing the demographic makeup of the country in order to make it a "purely African" nation. This was widely interpreted as a Tunisian (or Arabic) version of the great replacement conspiracy theory allegedly in an attempt to distract voters from the policy failures of his government.
Influence on white nationalist terrorism
Implicit call to violence
Camus's use of strong terms like "colonization" and "Occupiers" to label non-European immigrants and their children have been described as implicit calls to violence. Scholars like Jean-Yves Camus have argued that the "Great Replacement" conspiracy theory closely parallels the concept of "remigration", a euphemistic term for the forced deportation of non-white immigrants. "We shall not leave Europe, we shall make Africa leave Europe," Camus wrote in 2019 to define his political agenda for the European parliament elections. He has also used another euphemism, the "Great Repatriation", to refer to remigration.
According to historians Nicolas Bancel and Pascal Blanchard, along with sociologist Ahmed Boubeker, "the announcement of a civil war is implicit in the theory of the 'great replacement' [...] This thesis is extreme—and so simplistic that it can be understood by anyone—because it validates a racial definition of the nation." Sceptical of Camus's description of second or third generation immigrants as being itself a contradiction in terms—"they do not migrate anymore, they are French"—demographer Hervé Le Bras is also critical of their designation as a fifth column in France or an "internal enemy".
Inspired attacks
Fears of the white race's extinction, and replacement theory in particular, have been cited by several accused perpetrators of mass shootings between 2018, 2019 and 2022. While Camus has stated his own philosophy is a nonviolent one, analysts including Heidi Beirich of the Southern Poverty Law Center say the idea of white genocide has "undoubtedly influenced" American white supremacists, potentially leading to violence.
In October 2018, a gunman killed 11 people and injured 6 in an attack on the Tree of Life synagogue in Pittsburgh, Pennsylvania. The gunman believed Jews were deliberately importing non-white immigrants into the United States as part of a conspiracy against the white race.
Brenton Harrison Tarrant, the Australian terrorist responsible for the mass shootings at Al Noor Mosque and Linwood Islamic Centre in Christchurch, New Zealand, on 15 March 2019, that killed 51 people and injured 49, named his manifesto The Great Replacement, a reference to Camus's book. In response, Camus condemned violence while reaffirming his desire for a "counter-revolt" against an increase in nonwhite populations.
In 2019, research by the Institute for Strategic Dialogue showed over 24,000 social media mentions of the Great Replacement in the month before the Christchurch shootings, in comparison to just 3,431 mentions in April 2012. The use of the term spiked in April 2019 after the Christchurch mosque shootings.
Patrick Crusius, the suspect in the 2019 El Paso shooting, posted an online manifesto titled The Inconvenient Truth alluding to the "great replacement" and expressing support for "the Christchurch shooter" minutes before the attack. It spoke of a "Hispanic invasion of Texas" leading to "cultural and ethnic replacement" (alluding to the Reconquista) as justifications for the shooting.
The suspect accused in the 2022 Buffalo shooting listed the Great Replacement in a manifesto he had published prior to the attack. The suspect described himself as a fascist, white supremacist, and antisemite.
List of proponents
Elon Musk
Tucker Carlson
Davor Domazet-Lošo
Mark Finchem
Matt Gaetz
Jussi Halla-aho
Laura Ingraham
Ron Johnson
Hermann Kelly
Steve King
Giorgia Meloni, Prime Minister of Italy
Robert Ménard
Jean Messiha
Viktor Orbán, Prime Minister of Hungary
Riikka Purra
Wendy Rogers
Lauren Southern
John Waters, Irish writer
Éric Zemmour
Kais Saïed, President of Tunisia
Paul Golding
Michel Houellebecq
See also
White demographic decline
Counter-jihad
Eurabia
The Kalergi Plan conspiracy theory, another variant of the white genocide conspiracy theory that heavily revolves around a supposed plan to replace and racially mix white Europeans with non-whites through immigration by Richard Coudenhove-Kalergi, an Austrian-Japanese politician and founder of the Paneuropean Union
Demographic engineering
Race suicide theory of early 20th-century eugenicists
Reconquista (Southwest United States)
The Protocols of the Elders of Zion
The Rising Tide of Color Against White World-Supremacy
Yellow Peril
Declinism
Love Jihad conspiracy theory
Notes
References
Citations
Sources
Alba, Richard. The Great Demographic Illusion: Majority, Minority, and the Expanding American Mainstream (Princeton UP, 2020) https://doi.org/10.1515/9780691202112
Further reading
. in Swedish
2010 introductions
Alt-right
White genocide conspiracy theory
Eurabia
Anti-immigration politics in Europe
Far-right politics in France
Identitarian movement
Conspiracy theories involving Jews
Conspiracy theories promoted by Donald Trump
Conspiracy theories in France
Demography
Anti-immigration politics
Islamophobia in France | Great Replacement conspiracy theory | [
"Environmental_science"
] | 8,783 | [
"Demography",
"Environmental social science"
] |
56,303,902 | https://en.wikipedia.org/wiki/2-Methyleneglutaronitrile | 2-Methylene glutaronitrile is a dimerization product of acrylonitrile and a starting material for di- and triamines, for the biocide 2-bromo-2-(bromomethyl)pentanedinitrile and for heterocycles, such as 3-cyanopyridine.
Preparation
2-Methylene glutaronitrile is a side-product in the production of hexanedinitrile which is used (after hydrogenation to 1,6-diaminohexane) as a key component for engineering polymers such as the polyamides (PA 66) or polyurethanes. Hexanedinitrile can be industrially produced by electrochemical hydrodimerisation or by catalytic dimerization of acrylonitrile.
A catalytic tail-tail dimerization of two acrylonitrile molecules forms hexanedinitrile:
Also head-to-tail dimerization can occur in the process. In the presence of tricyclohexylphosphine (PCy3) a yield of up to 77% 2-methylene glutaronitrile can be obtained:
Metal halides (such as zinc chloride or aluminium chloride) are used with tertiary amines (such as triethylamine) as catalysts for the dimerization. Crude yields of up to 84% are achieved. Often, significant amounts of product are lost during the work-up (e. g. extraction and distillation) because of the tendency to polymerization of 2-methylene glutaronitrile.
In addition to the linear dimerization products 1,4-dicyano-2-butene and 1,4-dicyano-3-butene (obtained as cis-trans isomer mixtures) usually also other oligomers (and polymers) of acrylonitrile are formed. During the electrochemical hydrooligomerization of acrylonitrile, these are trimers, such as 1,3,6- and 1,3,5-tricyanohexane or tetramers, such as 1,3,6,8- and 1,3,5,8-tetracyanooctane. The reaction of acrylonitrile with tributylphosphine affords 2-methyleneglutaronitrile in a modest yield of about 10% after fractional distillation. The DABCO-catalyzed acrylonitrile dimerization of 2,4-dicyano-1-butene after 10 days at room temperature is with 40% yield similarly inefficient.
Use
The earlier patent literature describes processes for the isomerization of 2-methylene glutaronitrile to 1,4-dicyanobutenes as hexanedinitrile precursors, which became obsolete with the optimization of the electrochemical hydrodimerization of acrylonitrile to hexanedinitrile.
The electrochemical hydrodimerization of 2-methylene glutaronitrile produces 1,3,6,8-tetracyanooctane.
In the hydrogenation of 2-methylene glutaronitrile in the presence of palladium on carbon, hydrogen is attached to the double bond and 2-methylglutaronitrile is obtained in virtually quantitative yield.
The hydrogenation of the nitrile groups requires more severe conditions and the presence of ammonia or amines to suppress the formation of secondary amines. This second hydrogenation step is carried out with Raney-cobalt as the hydrogenation catalyst to give 2-methyl-1,5-pentanediamine in 80% yield.
Hydrogenation of 2-methylene glutaronitrile in the presence of ammonia with manganese-containing sodium oxide-doped cobalt catalyst (at 80 to 100 °C and pressures of 200 atm in a tubular reactor) leads to the addition of ammonia to the double bond and directly converts the compound to 2-aminomethyl-1,5-pentanediamine with yields of 66%.
The branched triamine can be used in epoxides and polyurethanes.
2-Methylenglutaronitrile reacts with methanamide upon catalysis with 4-(dimethylamino)-pyridine (DMAP) at 60 °C in 47% yield to give 1-(N-methanoylamino)-2,4-dicyanobutane, from which α- aminomethylglutaric acid is formed by subsequent hydrolysis.
Heating 2-methyleneglutaronitrile with an alkaline ion exchanger, pyridine and water to 150 °C in an autoclave yields the lactam 5-cyano-2-piperidone in 80% yield.
2-Methylene glutaronitrile can be polymerized to various homo- and copolymers via anionic polymerization with sodium cyanide, sodium in liquid ammonia or with butyllithium. However, the polymers are formed only in low yields and show unsatisfactory properties such as intrinsic viscosities and poor mechanical properties.
The main use of 2-methyleneglutaronitrile is as starting material for the broad-spectrum biocide 2-bromo-2-(bromomethyl)pentanedinitrile (methyldibromo-glutaronitrile), which is formed in virtually quantitative yield by the addition of bromine to the double bond.
From the chlorine-analogous 2-chloro-2-(chloromethyl)pentenenitrile, 3-cyanopyridine is obtained by heating to 150 °C with tin(IV)chloride.
References
Vinylidene compounds
Nitriles | 2-Methyleneglutaronitrile | [
"Chemistry"
] | 1,231 | [
"Nitriles",
"Functional groups"
] |
56,304,602 | https://en.wikipedia.org/wiki/Pollutant-induced%20abnormal%20behaviour | Pollutant-induced abnormal behaviour refers to the abnormal behaviour induced by pollutants. Chemicals released into the natural environment by humans impact the behaviour of a wide variety of animals. The main culprits are endocrine-disrupting chemicals (EDCs), which mimic, block, or interfere with animal hormones. A new research field, integrative behavioural ecotoxicology, is emerging. However, chemical pollutants are not the only anthropogenic offenders. Noise and light pollution also induce abnormal behaviour.
This topic is of special concern for its conservation and human health implications and has been studied greatly by animal behaviourists, environmental toxicologists, and conservation scientists. Behaviours serve as potential indicators for ecological health. Behaviour can be more sensitive to EDCs than developmental and physiological traits, and it was the behaviour of eagles that first drew attention to the now well-known dangers of DDT. However, behaviour is generally difficult to measure and can be highly variable.
Behaviours which are critical for survival, such as reproductive and social behaviours, and cognitive abilities like learning can be affected directly or indirectly by chemical pollutants— many examples have been documented, and their chemical culprits have been identified. These same behaviours can also be altered by anthropogenic noise and light, although their mechanisms are relatively unknown.
EDCs known to alter behaviour
Atrazine - a common herbicide
Bisphenol A - component of some plastics
Carbaryl
Cypermethrin - a common insecticide
DDT
DEHP
Dioxins and dioxin-like compounds
Endosulfan
Fenarimol - a common fungicide
Fenitrothion
Kepone
Lead compounds
Mercury compounds
Methoxychlor
Nonylphenol
PCBs
Vinclozolin
17β-trenbolone
Determining the link between such pollutants and altered behaviours often requires both field studies and laboratory studies. Field studies are useful in determining whether behavioural changes appear with pollution levels occurring in the environment, while laboratory studies can be used to clarify the mechanisms connecting an environmental pollutant to specific behavioural changes.
Mechanisms
EDCs affect the synthesis, storage, release, transport, clearance, receptor recognition, binding, or post-receptor responses of hormones. This results in either stimulative or inhibitive effects, resulting in overproduction or underproduction of hormones. The effects of hormones on behaviour have been well studied, and often produce direct behavioural effects by acting on the central nervous system. Indirectly, behaviours may be altered by hormones influencing an animal's metabolism or other important processes.
Since behaviours also influence hormones, chemical pollutants that induce behavioural changes may also affect hormone levels, which could result in more behavioural or other changes.
Applying Tinbergen’s four questions
Studies into the mechanisms underlying behavioural adjustments fall into a category of animal behaviour research described by Tinbergen.
Studies of animal behaviour typically pertain to one of Tinbergen’s four questions, and these can be applied to studies regarding chemical pollution. Questions of causation focus on how pollutant-exposure disrupts the mechanisms behind normal behaviour. For example, when differences in sexual behaviours were noted in wildlife after the introduction of DDT, biochemical experiments on rats were able to show that the pollutant was inhibiting androgen binding to androgen receptors.
Secondly, questions of ontogeny consider how exposure disrupts the development of behaviours. An example is when researchers examined the effects of an aerosol on the spatial learning of mice. Thirdly, questions of adaptation consider how behavioural modifications resulting from exposure will influence fitness. Scientists have investigated the reproductive success of white ibises exposed to methylmercury, for instance. Lastly, questions of phylogeny consider how phylogenetic history might predetermine sensitivity or resistance to pollutants in a particular behaviour. This could include investigating how animals that are better at learning might be better at avoiding toxins in the environment.
Effects on reproductive behaviours
Reproductive behaviour effects may involve changes in courtship and mating behaviours, mate choice, or changes in nest building. Most studies on this topic have been conducted on fish and birds. For example, treating adult male zebra fish with biphenol A for 7 weeks resulted in decreased courtship behaviour of females. 17β-trenbolone exposure in adult guppies and mosquitofish also altered female mate selection, as they preferred unexposed males. Guppies treated with atrazine during breeding and through gestation were less likely to engage in and showed fewer numbers of courtship displays and other reproductive behaviours. Additionally, females preferred untreated males.
Studies on birds show significant effects of EDCs on mating songs and displays. For example, treating female zebra finches with PCBs before egg laying resulted in a size reduction in the song centres of the chick’s brains. Methylmercury exposure at environmental levels for 3 years in male white ibises resulted in increased homosexual behaviour, decreased rates of key courtship behaviours, and less attractiveness to females. Mammals are also susceptible, and effects on individuals have been shown to have transgenerational and even population-level consequences. Illustrating this, female rats three generations removed from vinclozolin exposure show changes in mate preference, preferring unexposed mates, while male rats do not, and this could have complex effects on the population.
Conservation implications
Chemical-induced changes in animal behaviour often have consequences for wild populations. The effects of concern aren’t limited to reproductive effects, which have obvious implications for population vitality. For example, frogs exposed to pesticide-levels found in the environment demonstrate hyperactivity, whip-like convulsions, and depressed avoidance behaviour, which may increase their vulnerability to predation.
As well, guppies from crude oil-polluted environments are less exploratory after both short-term and long-term exposure. This may weaken their foraging efficiency and resource-use diversity, thus posing a threat to the population viability. This topic is therefore quite important for understanding how human-impacts on the environment may threaten populations. Additionally, if abnormal behaviours can be used as indicators of toxic pollution, then this provides a much more accessible mode of toxicology science. Therefore, there is potential for engaging citizen scientists in environmental research.
Noise and light pollution
Pollutants are not always chemicals. They can be other unnatural stimuli introduced to the environment by humans, such as noise and light pollution. Anthropogenic noise and light can result in altered antipredator behaviour, reproductive behaviour, communication, foraging behaviour, population distribution, male-male competition and more. However, the mechanisms behind these altered behaviours is relatively unknown within the literature.
Noise pollution
Birds
Noise pollution is widespread, which is mostly a result of transportation networks. Although there are many effects of noise pollution, two specific consequences are adjustments in population distribution and modified animal communication. Birds provide a clear example of both of these consequences. Altered population distributions can affect inter-species interactions. For example, the diversity of birds in the woodlands of New Mexico was significantly reduced in areas with unnatural noise levels. This change in diversity resulted in less nest predation, which was explained by the decreased presence of the dominant predator - the scrub-jay. This effect has also been observed in owls. A negative correlation was found between the noise intensity of an area and the probability that a long-eared owl will reside in that region. Suggested explanations for this outcome are that hunting efficiency was diminished and communication was less effective.
Noise pollution also affects conspecific communication. High noise levels may require animals to adjust their vocalizations in order for communication to remain effective. Bird songs are a well-studied component of animal communication. The use of adjusted songs was observed in Savannah sparrows residing in noisy environments. Adjusted songs were so distinct that their use in the control environment did not result in responses (i.e. aggressive territorial behaviour) typically observed when non-adjusted songs were vocalized. Failure to recognize conspecific vocalizations can also be detrimental to male-male competition. Male urban white-crowned sparrows approached stimulus songs of intruders more closely, regardless of song type, when in the presence of noise pollution. A higher frequency of harmful fights is a suggested consequence of this behaviour because of the relatively small distance between the intruding and defending males.
Marine animals
Noise pollution can also affect marine animals. There are many sources of noise in the world's oceans, such as the sounds produced by commercial shipping, sonars and acoustic deterrents. Unnatural noise levels can negatively affect reproductive behaviour, such as courtship behaviours. For example, painted goby males did not take part in visual courtship behaviour when in a noisy environment. Female painted gobies in this experiment were also less likely to spawn in a noisy environment. Noise pollution can also affect foraging behaviour in marine animals, which results in less effective strategies. Porpoises have been found to make fewer prey capture attempts, dive deeper, and cut their foraging behaviour short when a vessel passes by, which results in a higher energy expenditure. Shore crabs were also observed interrupting their foraging behaviour when in the presence of ship noise. Antipredator behaviour in marine animals has also been known to change when noise levels are high. Shore crabs took longer to return to their shelters when in the presence of ship noise. Neolamprologus pulcher (a cichlid fish) females defended their nest less against predators when boat noise was present.
Recommendations for marine animals
Specific mitigation strategies and recommendations have been presented by the Marine Mammal Commission (2007). They offer multiple ways to alleviate noise pollution in the ocean. Some strategies include removing the source of noise, employing sound attenuation devices, limiting the use of the sound source and monitoring operational requirements. They recommend improving research programs, creating consistent regulation standards that are better enforced and improving mitigation strategies.
Light pollution
Light pollution affects multiple aspects of animal behaviour, such as reproductive behaviour, foraging behaviour and antipredator behaviour. Altered reproductive behaviour has been observed in multiple taxa. Female crickets were less captious of males when they were raised in bright artificial light. Male crickets that were raised under continuous artificial light were discriminated against more than male crickets raised in darkness or moonlight. Female fireflies also altered their reproductive behaviour by failing to flash when placed under artificial light and males never flashed in response to these females. However, it is not only insects that are affected by light pollution. Male green frogs made less calls and moved more often when in the presence of artificial light. According to Baker and Richardson (2006), these behavioural changes negatively affect breeding success.
Another consequence of light pollution is the disruption of foraging behaviour in wildlife, such as where and when they forage or hunt. Beach mice used foraging patches near sodium vapor lights or yellow bug lights less often than non-lit patches and they also harvested fewer seeds from these lit patches. This study also hypothesizes that artificial light may alter the movement of mice because of predation risks. Bats are another animal that are greatly affected by light pollution. The presence of artificial lights is associated with a delayed emergence of bats from their dwellings and less time spent emerged. This alteration in foraging behaviour causes bats to miss the most optimal hunting time for insects. According to this study, as little as one hour of artificial light exposure after dusk disrupts the bats foraging behaviour, as well as growth rates.
Light pollution can also alter antipredator behaviour in wildlife. When moths come within a close proximity of a hunting bat, they make a powerdive towards the ground (Roeder & Treat, 1961). If moths are in the presence of artificial light, they are less likely to make this powerdive manoeuver, which results in a reduced ability to evade bat predation. A suggested explanation for this behaviour, according to this study, is that moths turn their ultrasound detection off in daylight (or simulated daylight). Predator-prey interactions are also altered by noise pollution. An example of this is in loggerhead turtles and ghost crabs. Ghost crabs are attracted to artificial lights and begin to exhibit more aggressive predatory behaviour in the presence of the light. This study hypothesizes that loggerhead hatchling predation would also increase as a result of this modified predatory behaviour and the predator-prey relationship would, therefore, be altered.
References
Pollutants
Toxicology
Problem behavior
Abnormal behaviour in animals
Ethology | Pollutant-induced abnormal behaviour | [
"Biology",
"Environmental_science"
] | 2,550 | [
"Behavior",
"Toxicology",
"Problem behavior",
"Behavioural sciences",
"Abnormal behaviour in animals",
"Ethology",
"Human behavior"
] |
56,304,859 | https://en.wikipedia.org/wiki/NGC%20519 | NGC 519, also occasionally referred to as PGC 5182, is an elliptical galaxy located approximately 242 million light-years from the Solar System in the constellation Cetus. It was discovered on 20 November 1886 by astronomer Lewis Swift.
Observation history
Swift discovered the object along with NGC 530, 538 and 557 using a 16-inch refractor telescope at the Warner Observatory. It was later catalogued by John Louis Emil Dreyer in the New General Catalogue, where the galaxy was described as "most extremely faint, very small, round, very difficult".
Description
The galaxy appears very dim in the sky as it only has an apparent visual magnitude of 14.4. It can be classified as type E using the Hubble Sequence. The object's distance of roughly 240 million light-years from the Solar System can be estimated using its redshift and Hubble's law.
See also
List of NGC objects (1–1000)
References
External links
SEDS
Elliptical galaxies
Cetus
0519
5182
Astronomical objects discovered in 1886
Discoveries by Lewis Swift | NGC 519 | [
"Astronomy"
] | 217 | [
"Cetus",
"Constellations"
] |
56,306,126 | https://en.wikipedia.org/wiki/American%20polyconic%20projection | In the cartography of the United States, the American polyconic projection is a map projection used for maps of the United States and its regions beginning early in the 19th century. It belongs to the polyconic projection class, which consists of map projections whose parallels are non-concentric circular arcs except for the equator, which is straight. Often the American polyconic is simply called the polyconic projection.
The American polyconic projection was probably invented by Swiss-American cartographer Ferdinand Rudolph Hassler around 1825. It was commonly used by many map-making agencies of the United States from the time of its proposal until the middle of the 20th century. It is not used much these days, having been replaced by conformal projections in the State Plane Coordinate System.
Description
The American polyconic projection can be thought of as "rolling" a cone tangent to the Earth at all parallels of latitude. This generalizes the concept of a conic projection, which uses a single cone to project the globe onto. By using this continuously varying cone, each parallel becomes a circular arc having true scale, contrasting with a conic projection, which can only have one or two parallels at true scale. The scale is also true on the central meridian of the projection.
The projection is defined by:
where:
is the longitude of the point to be projected;
is the latitude of the point to be projected;
is the longitude of the central meridian;
is the latitude chosen to be the origin at .
To avoid division by zero, the formulas above are extended so that if , then and .
See also
List of map projections
References
External links
Table of examples and properties of all common projections, from radicalcartography.net
An interactive Java Applet to study the metric deformations of the Polyconic Projection.
Map projections | American polyconic projection | [
"Mathematics"
] | 366 | [
"Map projections",
"Coordinate systems"
] |
56,306,256 | https://en.wikipedia.org/wiki/Nolder | In automotive design, a nolder is a small aerodynamic shape (a strip, wing, protrusion, lip or profile) integral to bodywork or to an aerodynamic attachment – e.g., a spoiler, diffuser or splitter – perpendicular to the direction of air flow travel for the purpose of further managing and refining air flow.
Nolders are used in both high-performance as well as in less critical aerodynamic applications.
Etymology
In 1996, Autocar attributed original use of the term to Ferrari, with other sources citing the nolder as having derived from Formula One racing, where Ferrari has been prominent.
The Formula One Dictionary defines a nolder as "a small upside-down L-shaped aerodynamic appendage generally positioned on the trailing edge of the rear wing to increase downforce at low speed."
The Automotive Dictionary defines it as a "very small aerodynamic appendage that's fitted to an airfoil to increase down-force without affecting drag resistance."
Applications
In the design of high-performance vehicles, a nolder of limited size can significantly increase or decrease the lift (Cz) of a vehicle's aerodynamic profile.
Nolders are also used in less high-performance applications, for example forcing an airflow separation alongside a vertical rear window to minimize debris accumulation, e.g., with a small hatchback.
Examples
Examples include the underside of the LaFerrari, which features a nolder to assist with vehicle dynamics. The Ferrari 599 GTO features prominent flanking aerodynamic fins or flying buttresses aside the rear window, maximizing air flow to a linear rear nolder. The Ferrari 355 has a similar nolder profile at the upper portion of its tail.
The Koenigsegg CCXR features an optional front splitter with a nolder, and the spoiler at the rear bumper of the Maserati 320S features a supplementary nolder to increase the vertical load to the rear.
Early versions of the highly aerodynamic 1982 Ford Sierra suffered crosswind instability, which was addressed in 1985 with the addition of aerodynamic nolders on the rear edge of the rubber seals of the rear-most side windows.
For airflow management and to assist in keeping the rear window free from dirt, nolders are integral to the rearmost vertical pillar of Mini Cooper models and the Fiat 500L.
See also
Diffuser (automotive)
Servo tab
Trim tab
References
Automotive body parts
Automotive styling features
Aerodynamics
Formula One | Nolder | [
"Chemistry",
"Engineering"
] | 500 | [
"Aerospace engineering",
"Aerodynamics",
"Fluid dynamics"
] |
56,306,721 | https://en.wikipedia.org/wiki/Electronic%20seal | An electronic seal is a piece of data attached to an electronic document or other data, which ensures data origin and integrity.
The term is used in the EU Regulation No 910/2014 (eIDAS Regulation) for electronic transactions within the internal European market.
Description
Conceptually similar to electronic signatures and usually technically realized as digital signatures, electronic seals serve as evidence that an electronic document was issued by a specific legal entity. For this purpose, an electronic seal must be linked to the data sealed with it in such a way that any subsequent change in the data is detectable and also in such a way that a fake seal cannot be created without access to the data (usually a private key) used for creation of the digital seal. This is usually achieved through use of a qualified digital certificate that is involved in creation of a digital seal. The unique private key used in the creation of the digital seal ensures non-repudiation: the entity that created the digital seal cannot later deny that it created the seal for that document. If the document is modified after its digital seal was created, the digital seal is not valid for the modified document. This can be checked by anyone with access of the public key corresponding to the private key used in the creation of the digital seal, ensuring the integrity of the sealed document.
Besides authenticating the document issued by the legal entity, e-Seals can also be used to authenticate any digital asset of the legal person, such as software code or servers. The important difference between a digital signature and an electronic seal is that the latter is usually created by a legal person while digital signatures are created by a natural person. For the creation of a digital signature, action of the person signing a document or data is required. In contrast, the creation of the digital seals can be incorporated in automated processes executed in a digital environment.
Qualified electronic seal
A qualified electronic seal is an electronic seal that is compliant to EU Regulation No 910/2014 (eIDAS Regulation) for electronic transactions within the internal European market. It enables to verify the issuer of a document over long periods of time. Qualified electronic seals can be considered as digital equivalent to seals of legal entities on paper. According to the eIDAS regulation, a qualified electronic seal must be created by a qualified electronic device and based on a qualified certificate for electronic seal.
References
Data security
European Single Market | Electronic seal | [
"Engineering"
] | 477 | [
"Cybersecurity engineering",
"Data security"
] |
56,307,570 | https://en.wikipedia.org/wiki/Dirichlet%27s%20ellipsoidal%20problem | In astrophysics, Dirichlet's ellipsoidal problem, named after Peter Gustav Lejeune Dirichlet, asks under what conditions there can exist an ellipsoidal configuration at all times of a homogeneous rotating fluid mass in which the motion, in an inertial frame, is a linear function of the coordinates. Dirichlet's basic idea was to reduce Euler equations to a system of ordinary differential equations such that the position of a fluid particle in a homogeneous ellipsoid at any time is a linear and homogeneous function of initial position of the fluid particle, using Lagrangian framework instead of the Eulerian framework.
History
In the winter of 1856–57, Dirichlet found some solutions of Euler equations and he presented those in his lectures on partial differential equations in July 1857 and published the results in the same month. His work was left unfinished at his sudden death in 1859, but his notes were collated and published by Richard Dedekind posthumously in 1860.
Bernhard Riemann said, "In his posthumous paper, edited for publication by Dedekind, Dirichlet has opened up, in a most remarkable way, an entirely new avenue for investigations on the motion of a self-gravitating homogeneous ellipsoid. The further development of his beautiful discovery has a particular interest to the mathematician even apart from its relevance to the forms of heavenly bodies which initially instigated these investigations."
Riemann–Lebovitz formulation
Dirichlet's problem is generalized by Bernhard Riemann in 1860 and by Norman R. Lebovitz in modern form in 1965. Let be the semi-axes of the ellipsoid, which varies with time. Since the ellipsoid is homogeneous, the constancy of mass requires the constancy of the volume of the ellipsoid,
same as the initial volume. Consider an inertial frame and a rotating frame , with being the linear transformation such that and it is clear that is orthogonal, i.e., . We can define an anti-symmetric matrix with this,
where we can write the dual of as (and ), where is nothing but the time-dependent rotation of the rotating frame with respect to the inertial frame.
Without loss of generality, let us assume that the inertial frame and the moving frame coincide initially, i.e., . By definition, Dirichlet's problem is looking for a solution which is a linear function of initial condition . Let us assume the following form,
and we define a diagonal matrix with diagonal elements being the semi-axes of the ellipsoid, then above equation can be written in matrix form as
where . It can shown then that the matrix transforms the vector linearly to the same vector at any later time , i.e., . From the definition of , we can realize the vector represents a unit normal on the surface of the ellipsoid (true only at the boundary) since a fluid element on the surface moves with the surface. Therefore, we see that transforms one unit vector on the boundary to another unit vector on the boundary, in other words, it is orthogonal, i.e., . In a similar manner as before, we can define another anti-symmetric matrix as
,
where its dual is defined as (and ). The Dirichlet's ellipsoidal problem then reduces to finding whether the matrix exists that determines the vector and that it is expressible in terms of two orthogonal matrices as in where, further
Let be the velocity field seen by the observer at rest in the moving frame, which can be regarded as the internal fluid motion since this excludes the uniform rotation seen by the inertial observer. This internal motion is found to given by
whose components, explicitly, are given by
These three components show that the internal motion is composed of two parts: one with a uniform vorticity with components
and the other with a stagnation point flow, i.e., . Particularly, the physical meaning of can be seen to be attributed to the uniform-vorticity motion. The pressure is found to assume a quadratic form, as derived by the equation of motion (and using the vanishing condition at the surface) given by
where is the central pressure, so that . Substituting this back in the equation of motion leads to
where is the gravitational constant and is diagonal matrix, whose diagonal elements are given by
The tensor momentum equation and the conservation of mass equation, i.e., provides us with ten equations for the ten unknowns,
Dedekind's theorem
It states that if a motion determined by is admissible under the conditions of Dirichlet's problem, then the motion determined by the transpose of is also admissible. In other words, the theorem can be stated as for any state of motions that preserves a ellipsoidal figure, there is an adjoint state of motions that preserves the same ellipsoidal figure.
By taking transpose of the tensor momentum equation, one sees that the role of and are interchanged. If there is solution for , then for the same , there exists another solution with the role of and interchanged. But interchanging and is equivalent to replacing by . The following relations confirms the previous statement.
where, further
The typical configuration of this theorem is the Jacobi ellipsoid and its adjoint is called as Dedekind ellipsoid, in other words, both ellipsoid have same shape, but their internal fluid motions are different.
Integrals
The tensor momentum equation admits three integrals, with regards to conservation of energy, angular momentum and circulation. The energy integral is found to be
where
Next, we have the integral
which signifies the conservation of , where the angular momentum components are given by
wherein is the total mass. Since the problem is invariant to the interchange of and , from the above integral, we obtain
where we substituted the formula for in terms of the vorticity vector . This integral signifies the conservation of , where the circulation components (in the inertial frame) are given by
See also
Maclaurin ellipsoid
Jacobi ellipsoid
References
Astrophysics
Fluid dynamics
Equations of astronomy | Dirichlet's ellipsoidal problem | [
"Physics",
"Chemistry",
"Astronomy",
"Engineering"
] | 1,272 | [
"Concepts in astronomy",
"Chemical engineering",
"Astrophysics",
"Equations of astronomy",
"Piping",
"Astronomical sub-disciplines",
"Fluid dynamics"
] |
56,307,833 | https://en.wikipedia.org/wiki/Mabel%20Gweneth%20Humphreys | Mabel Gweneth Humphreys (1911-2006) was a Canadian-American mathematician and Professor of Mathematics at Randolph-Macon Woman's College.
The M. Gweneth Humphreys Award of the Association for Women in Mathematics was established in her honor.
Education
Humphreys attended North Vancouver High School from 1925 to 1928.
She received her Bachelor of Arts with honors in mathematics from the University of British Columbia in 1932, where she held scholarships for all four years. She studied at Smith College under Susan Miller Rambo, among others. She earned a master's degree in mathematics in 1933. She received her Ph.D. in mathematics from the University of Chicago in 1935. Her dissertation was entitled On the Waring Problem with Polynomial Summands and her advisor was Leonard Eugene Dickson.
Career
In 1981, Humphreys described her first attempts to find a job after completing her Ph.D.:
From 1935 to 1936, Humphreys was an instructor of mathematics and physics at Mount St. Scholastica College. She began teaching at H. Sophie Newcomb Memorial College in 1936 and was promoted to assistant professor in 1941. She was also an assistant professor at Barnard College in the summer of 1944, and an assistant professor at Tulane University in the summer of 1946.
In 1949, Humphreys became an associate professor at Randolph-Macon Woman's College.
After one year at Randolph-Macon, she was named Gillie A. Larew Professor and head of the mathematics department. She was head of the department until 1979. For the 1955-1956 academic year, Humphreys went on sabbatical leave to the University of British Columbia (UBC). During this time, she visited undergraduate mathematics programs at several colleges and universities to examine their methods. From 1962 to 1963, she was a visiting professor at UBC as a National Science Foundation (NSF) faculty fellow.
In the summers, Humphreys taught high school teachers at NSF summer institutes.
From 1965 to 1969, Humphreys worked for the Educational Testing Service.
She was also a consultant in 1975 for the American Council on Education regarding mathematics course credit given by nonacademic organizations.
Humphreys was an active member of the Mathematical Association of America at both the sectional and national levels.
Awards and legacy
Humphreys earned the Governor General's Gold Medal in 1932, which was awarded to the college student with the highest grade point average in Canada.
The M. Gweneth Humphreys Award of the Association for Women in Mathematics is named in her honor. Each year, this award is presented to a mathematics educator who has encouraged women undergraduates to pursue mathematical careers.
Personal life
Humphreys was born on October 22, 1911 in South Vancouver, British Columbia. Her mother, Mabel Jane Thomas (1885-1963), was born in London, England, and worked as a dressmaker and a florist.
Her father was Richard Humphreys (1880-1969), a machinist who was born in Pwllheli, Wales. Her parents were married in 1910, and Humphreys was their only child. In 1941, Humphreys became a naturalized U.S. citizen.
Humphreys' hobbies included gardening and reading.
She was an active member of the Natural Bridge Appalachian Trail Club.
She lived in Lynchburg, Virginia, through her retirement in 1980 until her death on October 6, 2006.
References
External links
Honoring American Women in Mathematics: Pre-World War II PhD’s (Smithsonian National Museum of American History).
20th-century Canadian mathematicians
Canadian women mathematicians
20th-century American mathematicians
Number theorists
Randolph–Macon College faculty
University of Chicago alumni
University of British Columbia alumni
Smith College alumni
1911 births
2006 deaths
20th-century American women mathematicians
20th-century Canadian women scientists
20th-century American women scientists
Canadian emigrants to the United States
Scientists from Vancouver
Naturalized citizens of the United States | Mabel Gweneth Humphreys | [
"Mathematics"
] | 772 | [
"Number theorists",
"Number theory"
] |
56,309,176 | https://en.wikipedia.org/wiki/Microporellus%20adextrinoideus | Microporellus adextrinoideus is a species of poroid fungus in the family Polyporaceae that was described as a new species in 2007. The holotype, collected in Ivindo National Park (Ogooué-Ivindo Province, Gabon), was found growing on soil among mosses at the base of a dead tree stump. The fungus makes a semicircular, cork-coloured fruit body that is up to tall. Its spores are more or less ellipsoid in shape, with typical dimensions of 6.4 by 4.7 μm. At the time of publication, M. adextrinoideus is the only Microporellus species having skeletal hyphae that are non-dextrinoid.
References
adextrinoideus
Fungi described in 2007
Fungi of Africa
Fungus species | Microporellus adextrinoideus | [
"Biology"
] | 174 | [
"Fungi",
"Fungus species"
] |
56,310,192 | https://en.wikipedia.org/wiki/Self-propulsion | Self-propulsion is the autonomous displacement of nano-, micro- and macroscopic natural and artificial objects, containing their own means of motion. Self-propulsion is driven mainly by interfacial phenomena. Various mechanisms of self-propelling have been introduced and investigated, which exploited phoretic effects, gradient surfaces, breaking the wetting symmetry of a droplet on a surface, the Leidenfrost effect, the self-generated hydrodynamic and chemical fields originating from the geometrical confinements, and soluto- and thermo-capillary Marangoni flows. Self-propelled system demonstrate a potential as micro-fluidics devices and micro-mixers. Self-propelled liquid marbles have been demonstrated.
See also
Self propelled particles
References
Mechanical engineering
Surface science | Self-propulsion | [
"Physics",
"Chemistry",
"Materials_science",
"Engineering"
] | 159 | [
"Surface science",
"Applied and interdisciplinary physics",
"Condensed matter physics",
"Mechanical engineering"
] |
56,311,333 | https://en.wikipedia.org/wiki/University%20of%20North%20Carolina%20-%20Coastal%20Studies%20Institute | The UNC Coastal Studies Institute (or UNC-CSI) is a campus used for research of the coastal environments and eco-systems, at 850 NC-345, Wanchese, in the Outer Banks of North Carolina, United States. The campus serves East Carolina University, UNC Chapel Hill, North Carolina State University, UNC Wilmington and Elizabeth City State University.
UNC-CSI is a research facility, on a site along the Croatan Sound on the Outer Banks near the town of Manteo. The facility includes research labs for marine archaeology, coastal processes, estuarine ecology, public policy and engineering. The building also houses classrooms and laboratories, along with marine operations, administration and research offices.
Design
The building plans for the UNC-CSI campus were designed considering guidelines set forth by the LEED program. Designers focused heavily on low energy use and water conservation. The campus contains sustainable features, including the building itself and the landscape design throughout the campus. The UNC-CSI building is LEED Gold certified (the second highest certification possible). LEED scores on a point system, from 40 (standard certification) to 80+ points for a Platinum certification. UNC-CSI was awarded 64 points and a Gold certification in 2014. The designers achieved this by integrating sustainable building materials and sustainable technologies. There are six categories in which LEED scores on, UNC-CSI's campus scored in all categories, the first being alternative transportation. This includes bicycle storage and preferred parking for low emission and carpool vehicles. On storm-water management and landscape design, 71% of the site is open space. The energy consumption is reduced by 37% and portable water consumption is reduced by 75%. 24% of the building materials are recycled and 75% of on-site waste was also recycled. The UNC Coastal Studies Institute was also designed for 95% of occupiable space to be exposed to daylight.
References
University of North Carolina
Environmental research institutes
Research institutes in North Carolina
Roanoke Island | University of North Carolina - Coastal Studies Institute | [
"Environmental_science"
] | 408 | [
"Environmental research institutes",
"Environmental research"
] |
56,311,337 | https://en.wikipedia.org/wiki/HotelOnline | HotelOnline is a travel technology company, offering a suite of digital tools for e-commerce, online marketing and operations automation to the hotel industry in Sub-Saharan Africa. The company helps hotels digitize operations and offers managed distribution to online channels, such as Online Travel Agents (OTAs), Global Distribution Systems, and metasearch engines.
Background
HotelOnline was founded in 2014, by Endre Opdal and Håvar Bauck, to facilitate e-commerce and online marketing for hotels in Eastern Africa. Initially operating as Savanna Sunrise, the company grew rapidly in Kenya, Uganda and Rwanda in 2015 and 2016. After merging with a Polish competitor in 2017, the company rebranded to HotelOnline and expanded operations to Nigeria. Later in 2017, HotelOnline raised USD 250,000 in an equity crowdfunding, becoming the first known case of an African company successfully using this funding method.
In May 2018, HotelOnline acquired Senegalese travel technology company Teranga Solutions as part of their expansion into francophone Western Africa. The company at the same time also acquired European Travel Group AS.
In 2019, prominent startup investor Shravan Shroff invested an undisclosed amount in HotelOnline, and joined their Board of Directors. Shroff is known for his role as the first investor in traveltech unicorn OYO Rooms. Trond Riiber-Knudsen, known as Norway's most active startup investor, also co-invested an undisclosed amount.
In September 2019, as part of their expansion into the Nordic market, HotelOnline acquired the Norwegian operations of Key Butler, a leading Nordic short term apartment rental company.
In 2020, HotelOnline acquired former competitor Africabookings, and the Cloud9 Lifestyle app. This received some notable attention, as HotelOnline was seen as going against the stream when most of the travel industry in Africa was in a crisis.
In April 2022, Yanolja, a South Korean travel technology firm backed by Softbank and Booking.com announced their investment of an undisclosed amount in HotelOnline. Later, in September 2022, HotelOnline announced the USD 1.9 million acquisition of Kenyan competitor HotelPlus.
Technology
HotelOnline provides a cloud-based suite of tools for automated online distribution and hotel operations, reservations management and AI-driven dynamic pricing.
References
Travel technology
Digital marketing companies
E-commerce
Technology companies of Kenya
Tourism in Africa
Hospitality industry in Africa | HotelOnline | [
"Technology"
] | 492 | [
"Information technology",
"E-commerce"
] |
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