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54,344,800 | https://en.wikipedia.org/wiki/Crustoderma%20dryinum | Crustoderma dryinum is a species of crust fungus in the family Meruliaceae, and the type species of the genus Crustoderma. It is found in Europe and Asia, where it causes a brown rot on conifer wood.
References
Fungi described in 1873
Fungi of Asia
Fungi of Europe
Meruliaceae
Taxa named by Miles Joseph Berkeley
Fungus species | Crustoderma dryinum | [
"Biology"
] | 73 | [
"Fungi",
"Fungus species"
] |
54,345,151 | https://en.wikipedia.org/wiki/Skeletocutis%20inflata | Skeletocutis inflata is a species of poroid fungus in the family Polyporaceae. Found in Guangdong, China, it was described as a new species in 2013 by mycologist Bao-Kai Cui. The fungus is characterized by having fruit bodies with caps, and small pores numbering 8–10 per millimetre. Microscopically, it features inflated skeletal hyphae (after which it is named) that partially dissolve in a solution of potassium hydroxide (KOH). The skeletal hyphae in the trama are parallel along the tubes.
References
Fungi described in 2013
Fungi of China
inflata
Taxa named by Bao-Kai Cui
Fungus species | Skeletocutis inflata | [
"Biology"
] | 141 | [
"Fungi",
"Fungus species"
] |
54,345,232 | https://en.wikipedia.org/wiki/Journal%20of%20Astronomical%20Telescopes%2C%20Instruments%2C%20and%20Systems | Journal of Astronomical Telescopes, Instruments, and Systems is a quarterly, peer-reviewed scientific journal covering the development, testing, and application of telescopes, instrumentation, techniques, and systems for ground- and space-based astronomy, published by SPIE. The editor-in-chief is Megan Eckart (Lawrence Livermore National Laboratory, USA).
Abstracting and indexing
The journal is abstracted and indexed in:
SAO/NASA Astrophysics Data System (ADS)
Science Citation Index Expanded
Current Contents - Engineering, Computing & Technology
Inspec
Scopus
Ei/Compendex
According to the Journal Citation Reports, the journal has a 2020 impact factor of 1.436.
References
External links
Optics journals
Engineering journals
SPIE academic journals
English-language journals
Academic journals established in 2015 | Journal of Astronomical Telescopes, Instruments, and Systems | [
"Astronomy"
] | 160 | [
"Astronomy journal stubs",
"Astronomy stubs"
] |
54,345,393 | https://en.wikipedia.org/wiki/Monosodium%20xenate | Monosodium xenate is the sodium salt of xenic acid with formula NaHXeO4. It is a powerful oxidizer, owing to being a highly reactive compound of xenon.
Synthesis
Monosodium xenate can be made by mixing solutions of xenon trioxide and sodium hydroxide, followed by freezing to liquid nitrogen temperatures, and dehydrating in a vacuum.
Properties
Monosodium xenate usually exists in the sesquihydrate form, with 1.5 waters of hydration per unit molecule. It is stable up to 160 °C heated in a pure state. However it can explode when subjected to mechanical shock, or lower temperatures when mixed with XeO3.
Sodium xenate is slightly toxic with a median lethal dose between 15 and 30 mg/kg of body weight in mice. Xenate leaves the body very quickly. In mice, the level in blood drops by half in twenty seconds due to it being decomposed and exhaled. In the peritoneum the half-life extends to six minutes.
The dialkali xenates XeO42- have not been discovered, as xenate disproportionates in more alkaline conditions, hence it being rare to the find the dialkaline salt Na2XeO4.
References
Xenon(VI) compounds
Oxidizing agents
Sodium compounds | Monosodium xenate | [
"Chemistry"
] | 285 | [
"Redox",
"Oxidizing agents"
] |
54,346,164 | https://en.wikipedia.org/wiki/Wirelesspt | Wirelesspt is a non-commercial open grassroots initiative to support free computer networks that is not dependent of central infrastructure, corporation or entity which is done by the ordinary citizen provide free, open and democratic access to the highways of information technologies helping people and organizations implementing wireless networks that will benefit their communities.
The project also invests in investigating free, open source, digital, information and telecommunication technologies as well as to promote, educate and supply technological information to teach and educate its surrounding social environment about the importance of online privacy and security.
WirelessPT is also part of an international movement for wireless community networks in Europe. The Project counts with local communities and was started in the community of Moitas Venda in Portugal.
Goals
The main goal of WirelessPT is to build a large scale free wireless Wi-Fi network that is decentralized and owned by those who run it and to support local communication. The project is governed by its own agreement which was inspired in the Pico peering Agreement where participants agree upon a network that is free from discrimination and upholds net neutrality. Among other communities like guifi.net and freifunk, WirelessPT has and shares similarities.
Among several goals the project includes:
Development of mesh networks for communities built by the ordinary citizen
Foster free access to communication technologies
Establish wireless connectivity with other communities and regions
Sharing and developing technological communication resources with and for their communities
Promote, educate and provide technical information on wireless networks to communities environment about the importance of online privacy, security and democracy.
Technology
Like many other free community-driven networks, Wirelesspt uses mesh technology to bring up ad hoc networks by interconnecting multiple Wireless LANs using mobile ad hoc network technology and a special routing software.
If one of these routers fail, this special software automatically calculates a new path to the final destination. This software is called mvwrt firmware. It is based on OpenWrt and other free software such as LEDE and was specifically designed for the needs and challenges of the project.
There are many different developed versions of the firmware depending on the hardware and protocols that local communities decide to use. Having previously tested olsr, WirelessPT decided to work with Ad Hoc and the B.A.T.M.A.N. routing protocol as the firmware base routing protocol.
History
Founded in January 2011 in Portugal after 2 years of planning the project was first started by its founder with a setup of 9 nodes and 5 gateways in 3 weeks to cover an area of 6 square kilometres using ddwrt firmware.
In 2013 the project developed its own firmware and expanded their nodes count as well as coverage until today and became a registered national trademark in 2016 after participating in the Battlemesh v9 event.
The project is currently active and stable also because it very easy to install the wireless kit specifically created for non-tech-savvy users and with the use of the self-managed and auto configured firmware on off-the-shelf wireless routers a node is fully functional without human interaction soon as the firmware is uploaded to a node.
During its development of the project, it also created one of the best sources of dyi wireless documentation that can be found online offering solutions for small to large projects.
External links
Official website also available on the Tor hidden service network]
Video clip on youtube that explains the project
Firmware Information (Translation bar provided on the wiki)
Portuguese mesh network
Wireless presentation at University of Minho
Presentation Wireless Battle Mesh v9 2016 at INESC TEC
Supporter on making regulation work community networks
Pico Peering Agreement
Wireless Networking in the developing world. A practical guide to planning and building low-cost telecommunications infrastructure, 3rd edition, Feb. 2013
Custom firmware
Wireless
Wireless networking
Community networks | Wirelesspt | [
"Technology",
"Engineering"
] | 756 | [
"Wireless",
"Wireless networking",
"Telecommunications engineering",
"Computer networks engineering"
] |
54,347,634 | https://en.wikipedia.org/wiki/Nested%20sequent%20calculus | In structural proof theory, the nested sequent calculus is a reformulation of the sequent calculus to allow deep inference.
References
Proof theory
Logical calculi | Nested sequent calculus | [
"Mathematics"
] | 34 | [
"Mathematical logic stubs",
"Mathematical logic",
"Logical calculi",
"Proof theory"
] |
54,349,009 | https://en.wikipedia.org/wiki/Ugeoji | In Korean cuisine, ugeoji () is outer leaves or stems of cabbage, radish, and other greens, which are removed while trimming the vegetables.
Ugeoji is often used in soups and stews, including haejang-guk (hangover soup).
Gallery
See also
Siraegi – dried radish greens
References
Food ingredients
Korean cuisine | Ugeoji | [
"Technology"
] | 81 | [
"Food ingredients",
"Components"
] |
54,349,569 | https://en.wikipedia.org/wiki/Investigative%20genetic%20genealogy | Investigative genetic genealogy, also known as forensic genetic genealogy, is the emerging practice of utilizing genetic information from direct-to-consumer companies for identifying suspects or victims in criminal cases. As of December 2023, the use of this technology has solved a total of 651 criminal cases, including 318 individual perpetrators who were brought to light. There have also been 464 decedents identified, as well as 4 living Does. The investigative power of genetic genealogy revolves around the use of publicly accessible genealogy databases such as GEDMatch and Family TreeDNA. On GEDMatch, users are able to upload their genetic data from any direct-to-consumer company in an effort to identify relatives that have tested at companies other than their own.
Identifying unknown subjects through investigative genetic genealogy is done through the use of analysis of identity-by-descent (IBD) segments of DNA that indicate shared ancestors. Data available in GEDMatch, which is composed of genetic profiles from approximately 1.2 million individuals, has proven capable of identifying a third cousin or closer in over 90% of the population. This information, used in tandem with demographic identifiers like age, gender, and place of residence, is sufficient for identifying any person who has a third cousin or closer within a publicly accessible genetic genealogy database.
Law enforcement agencies have leveraged the access to public databases by uploading crime-scene genealogy data and inferring relatives to potential suspects. Family tree assembly and analysis of demographic identifiers is then carried out by genetic genealogy experts, either working directly for law enforcement agencies or through one of the many US companies that have been set up to work on these cases. Parabon Nanolabs is the most well known company working in this field. By January 2021 Parabon claimed to have used genetic genealogy to produce an investigative lead in over 200 cases. The DNA Doe Project, a non-profit organization, have also been instrumental in resolving unidentified remains cases, many of whom are victims of violent crimes.
Field Application
There are more uses to investigative forensic genealogy than cold cases or cases otherwise deemed "unsolvable" by law enforcement. Natural disasters such as floods, wildfires, earthquakes are all prime examples of scenarios where gene-matching can be utilized. In instances where the body is unidentifiable by standard means, such as facial recognition or dental records, genetic technology can be used.
A number of living doe situations have also been solved this way. There is push to provide more resources for DNA to be offered when there is a need to identify a child who has been trafficked, or an adult who was trafficked at a young age.
Agencies that fall under the US Department of Justice, who have jurisdiction on the case(s) and/or person(s), can utilize forensic genetic genealogical DNA analysis and searching, FGGS for short. There are specific rules they must follow in order to use the system.
Complications
The use of investigative genetic genealogy has been central in numerous high-profile cases, namely in the identification and ultimate arrest of Joseph DeAngelo, the Golden State Killer. Despite its apparent success, the growing use of genetic genealogy databases by law enforcement agencies has not avoided serious scrutiny. A year prior to the arrest of DeAngelo, an individual was wrongly identified as a suspect in the murder of Angie Dodge, an 18-year-old woman who was the victim of a 1996 murder in Idaho Falls, Idaho. Michael Usry was the subject of a police investigation that led to a court order requiring Ancestry.com to disclose the identity of a partial match to crime scene DNA. This partial match was Usry, who was ultimately cleared as a suspect after police secured a warrant for his DNA. This DNA test proved that he was not a full match to the perpetrator.
Privacy implications
Direct-to-consumer companies
The use of genetic genealogy databases by investigators has initiated a debate over the Fourth Amendment implications of genealogy data. The Fourth Amendment states that a warrant is required in situations that violate an individual's reasonable expectations of privacy. Given the sensitivity of information within direct-to-consumer genealogy databases, particularly concerning medical traits, behavioral tendencies, ethnic background, and familial associations, courts have asserted that they are subject to protection under the Fourth Amendment.
Currently, direct-to-consumer companies do not promise complete protection of user data. 23andMe, a leading consumer genealogy company, states in its privacy policy that “23andMe will preserve and disclose any and all information to law enforcement agencies or others if required to do so by law or in the good faith belief that such preservation or disclosure is reasonably necessary to…comply with legal or regulatory process”.
In an effort to remain transparent to its consumers, 23andMe has a quarterly Transparency Report. This report identifies the number of government requests for user data in addition to the number of times data has been produced without the explicit consent of the individual(s) of interest. 23andMe claims to have never produced user data without consent. The other industry leader, Ancestry.com, takes an analogous stance on the privacy of user data and similarly provides an annual transparency report.
The direct-to-consumer genealogy company FamilyTreeDNA faced a backlash following an admission that they were working secretly with the FBI. This partnership was initiated in 2018 and had the goal of solving cold cases involving murder and rape. Following scrutiny, FamilyTreeDNA's president Bennett Greenspan apologized for a lack of transparency, stating "I am genuinely sorry for not having handled our communications with you as we should have".
Public genetic genealogy databases
Privacy implications pertaining to public databases like GEDMatch are distinct from direct-to-consumer companies. As users voluntarily upload their genealogy profiles to GEDMatch, they forfeit their privacy to the data. The third-party doctrine, originally established by the US Supreme Court, states that a person “has no legitimate expectation of privacy in information…voluntarily turn[ed] over to third parties”. However, following intense media attention after the arrest of the Golden State Killer, GEDMatch changed their terms of service to require individuals to opt into use of their profiles by third parties. In effect, privacy rights were shifted back into the hands of the users.
Potential for supplementing the FBI's CODIS System
The US government's own Combined DNA Index System (CODIS) database is composed of forensic evidence assessable to local, state, and federal law enforcement officials. This database consists of genetic profiles of approximately 18 million different people, however these are limited to DNA samples from convicted felons and arrestees. Data on the racial distribution of profiles suggests that 8.6% of the entire African American population is present in the database compared to only 2% of the white population.
On the other hand, genetic profiles from direct-to-consumer databases and GEDMatch consist of 75% white individuals from Northern European descent. The vast overrepresentation of African American individuals within the CODIS database has rendered it relatively ineffective for solving serial murder and sexual assault cases, of which the majority of perpetrators are white. Based on data from 4,700 mass murderers, 57% of serial killers are white whereas only 29% are African American. It has been suggested that the use of investigative genetic genealogy, which relies heavily on databases like GEDMatch, would therefore help to reduce racial disparities in the current criminal justice system. However, in practice it has been found that the majority of victims identified through this technique were white.
Investigative Genetic Genealogy Centers
The world's first Investigative Genetic Genealogy Center was launched at the Ramapo College of New Jersey in December of 2022. The center offers student workshops, certificate programs, and bootcamps for interested practitioners around the world. The center is led by David Gurney and Cairenn Binder.
See Also
Public genealogy databases known to have been used in IGG:
FamilyTreeDNA
GEDMatch
MyHeritage
Genetic genealogy laboratories known to assist with IGG:
DNA Solutions, Inc.
Othram, Inc.
Parabon NanoLabs
References
Genetic genealogy
Forensic disciplines
Genealogy
Forensic genetics | Investigative genetic genealogy | [
"Biology"
] | 1,647 | [
"Phylogenetics",
"Genealogy"
] |
55,917,496 | https://en.wikipedia.org/wiki/Spt-Ada-Gcn5%20acetyltransferase | Spt-Ada-Gcn5 acetyltransferase (SAGA) complex is a multicomponent regulator of acetylation. It has been found that this complex is highly conserved between different organisms, such as humans, Drosophila, and yeast. This 15 subunit complex has been best characterized for its histone acetyltransferase activity (HAT). The acetylating activity has been found to occur in the lysine residues of the N-terminal tails of H3 and H2 histones. It has been found recently that this activity is actually a deubiquitination of a monoubiquitin that occurs in residue Lys 123 of the H2b histone and the acetylation of the H3 histone. The histone acetylation is mediated by the GCN5 histone acetyl transferase, while the deubiquitinating activity is mediated by a deubiquitinating module (DUBm), which is composed of 4 proteins, Ubp8 ubiquitin hydrolase, Sgf11, Sus1, and Sgf73. This DUB module is an independently folding subcomplex that is connected to the C-terminal tail of Sgf 73, Sgf73, as well as Sus1, also have a role in facilitating SAGA complex's role in nuclear export by binding to components of the nuclear pore complex. Even though Ubp8 has ubiquitin specific hydrolase (USP) domain, the protein remains inactive unless it is in complex with the other 3 DUBm proteins.
References
Transferases | Spt-Ada-Gcn5 acetyltransferase | [
"Chemistry"
] | 342 | [
"Molecular biology stubs",
"Molecular biology"
] |
55,918,390 | https://en.wikipedia.org/wiki/Polynomial%20functor | In algebra, a polynomial functor is an endofunctor on the category of finite-dimensional vector spaces that depends polynomially on vector spaces. For example, the symmetric powers and the exterior powers are polynomial functors from to ; these two are also Schur functors.
The notion appears in representation theory as well as category theory (the calculus of functors). In particular, the category of homogeneous polynomial functors of degree n is equivalent to the category of finite-dimensional representations of the symmetric group over a field of characteristic zero.
Definition
Let k be a field of characteristic zero and the category of finite-dimensional k-vector spaces and k-linear maps. Then an endofunctor is a polynomial functor if the following equivalent conditions hold:
For every pair of vector spaces X, Y in , the map is a polynomial mapping (i.e., a vector-valued polynomial in linear forms).
Given linear maps in , the function defined on is a polynomial function with coefficients in .
A polynomial functor is said to be homogeneous of degree n if for any linear maps in with common domain and codomain, the vector-valued polynomial is homogeneous of degree n.
Variants
If “finite vector spaces” is replaced by “finite sets”, one gets the notion of combinatorial species (to be precise, those of polynomial nature).
References
Functors | Polynomial functor | [
"Mathematics"
] | 280 | [
"Functions and mappings",
"Mathematical structures",
"Category theory stubs",
"Mathematical objects",
"Category theory",
"Functors",
"Mathematical relations"
] |
55,918,466 | https://en.wikipedia.org/wiki/Bismuth%20polycations | Bismuth polycations are polyatomic ions of the formula . They were originally observed in solutions of bismuth metal in molten bismuth chloride. It has since been found that these clusters are present in the solid state, particularly in salts where germanium tetrachloride or tetrachloroaluminate serve as the counteranions, but also in amorphous phases such as glasses and gels. Bismuth endows materials with a variety of interesting optical properties that can be tuned by changing the supporting material. Commonly-reported structures include the trigonal bipyramidal cluster, the octahedral cluster, the square antiprismatic cluster, and the tricapped trigonal prismatic cluster.
Known materials
Crystalline
Bi5(AlCl4)3
Bi8(AlCl4)2
Bi5(GaCl4)3
Bi8(GaCl4)2
Metal complexes
[CuBi8][AlCl4]3
[Ru(Bi8)2]6+
[Ru2Bi14Br4][AlCl4]4
Structure and bonding
Bismuth polycations form despite the fact that they possess fewer total valence electrons than would seem necessary for the number of sigma bonds. The shapes of these clusters are generally dictated by Wade's rules, which are based on the treatment of the electronic structure as delocalized molecular orbitals. The bonding can also be described with three-center two-electron bonds in some cases, such as the cluster.
Bismuth clusters have been observed to act as ligands for copper and ruthenium ions. This behavior is possible due to the otherwise fairly inert lone pairs on each of the bismuth that arise primarily from the s-orbitals left out of Bi–Bi bonding.
Optical properties
The variety of electron-deficient sigma aromatic clusters formed by bismuth gives rise to a wide range of spectroscopic behaviors. Of particular interest are the systems capable of low-energy electronic transitions, as these have demonstrated potential as near-infrared light emitters. It is the tendency of electron-deficient bismuth to form sigma-delocalized clusters with small HOMO/LUMO gaps that gives rise to the near-infrared emissions. This property makes these species potentially valuable to the field of near-infrared optical tomography, which exploits the near-infrared window in biological tissue.
References
Bismuth compounds
Cations
Cluster chemistry | Bismuth polycations | [
"Physics",
"Chemistry"
] | 500 | [
"Matter",
"Cluster chemistry",
"Cations",
"Organometallic chemistry",
"Ions"
] |
55,918,702 | https://en.wikipedia.org/wiki/Digital%20pill | A digital pill (also known as a smart pill, or ingestible sensor) is a pharmaceutical dosage form that contains an ingestible sensor inside of a pill. The sensor begins transmitting medical data after it is consumed. The technology that makes up the pill, as well as the data transmitted by the pill's sensor, are considered to be part of digital medicine. The purpose of the sensor is to determine whether the person is taking their medication or not (called "compliance").
There are privacy concerns with respect to who receives the data and what is done with it. Such concerns, along with uncertain economic benefits, have made the broad introduction of digital pills in the healthcare practice challenging, despite accumulating body of clinical evidence indicating their efficacy and safety.
Overview
The first emergence of a swallowable electronic device was in 1957, this device used radio frequency to transmit temperature and pressure readings. The field lay stagnant until technology caught up with invention in the 1990s.
The first digital pill to be approved by the United States Food and Drug Administration (FDA), a version of aripiprazole (Abilify) manufactured by Otsuka Pharmaceutical, was approved in November 2017. This digital pill's sensor, developed by Proteus Digital Health, is activated by acid in the stomach, and generates an electrical signal that is picked up by a patch worn on the ribcage; the patch in turn forwards information to a smartphone app. The drug is taken by people with schizophrenia. People with the condition tend to have problems with adherence, and the digital pill could help with that; however, some people with schizophrenia have paranoia which the digital pill could make worse.
A video from the Wall Street Journal that shows an overview of how digital pills work can be found here.
Types
The most common types of ingestible sensors are used for imaging, sensing different types of gasses, to monitor medication compliance or absorption of medication, and electrochemical signal sensing.
Imaging
Images and video require the highest bandwidth for data delivery. Ingestible capsules containing video cameras are used for generating images of the macroscopic structures of hollow organs, such as the stomach and small bowel. These devices are powered by batteries, can transmit video at up to 2.7 Mbit/s, and are less invasive than other traditional endoscopic imaging devices.
Gas sensing
Gas sensing capsules utilize a gas-permeable membrane surrounding an electrochemical gas sensor and are primarily used to detect the partial-pressures of different gasses produced as the byproduct of metabolic reactions by bacteria in the intestines. The presence of gasses like carbon dioxide and methane in the gut provides useful data for analysis of metabolic and digestional health. This internal measurement of a body's organs provides a superior analysis in terms of accuracy and reliability as compared to the traditional technique of breath-test analysis.
Medication monitoring
Ingestible sensors that are specific for the monitoring of the absorption of medication or compliance will also signal the user that medication needs to be taken. These are activated in the stomach by pH differences and will transmit via Bluetooth.
Electrochemical sensing
Voltammetry can be used in vitro on stool liquid as a Gi tract diagnostic tool. The device would be able to perform cyclic, square wave, and differential pulse voltammetries.
Sensing targets
Due to the nature of ingestible sensors, they are optimized for passage through hollow organs. This makes them ideal for data collection throughout the digestive tract, which includes multiple organs between the mouth and anus.
Oral cavity
The most common clinical targets for the ingestible sensor in the oral cavity would aid in the determination of: electrolyte imbalances, body metabolism based on chemical makeup of saliva, hormonal imbalances, infectious conditions, i.e. HIV and viral hepatitis, allergy disorders and cancer.
Esophagus
Digital pills that have imaging capabilities are used in endoscopy to look for inflammation and lacerations in the esophagus. The mucosa contained in the esophagus can also be tested to look for issues such as eosinophilic esophagitis.
Stomach
The pH value of the stomach is important for proper digestion and is something that can be detected by certain types of digital pills. Stomach enzymes and electrolyte production are also able to be detected by a digital pill. These pills can also search for specific bacteria in various areas of the body. For example, digital pills can be programmed to search for helicobacter pylori in the stomach, which is known to be a cause of ulcers.
Colon
The potential targets would be to monitor stool (colonic content) for medical diagnosis of infection (parasite, viral, or bacterial sources), poor nutrient absorption, or colon cancer. Also, the ingestible sensor could do an internal colonoscopy that would be less invasive than traditional.
Power sources
Most digital pills use silver-oxide batteries. Lithium ion batteries are dangerous to the human bodies digestive system and therefore cannot be used.
Locomotion
Most digital pills rely on passive locomotion, or allowing the body's digestive system to do all the work moving the pill, however some pills do utilise active locomotion. One active locomotion method is to include a small magnet in the digital pill that can then be activated by an external magnetic field, which can then move the pill from outside the body.
Safety
It is possible that the digital pill and pacemakers may interfere with each other, however, this has not been verified.
References
Medical devices
Telemedicine | Digital pill | [
"Biology"
] | 1,143 | [
"Medical devices",
"Medical technology"
] |
55,919,158 | https://en.wikipedia.org/wiki/NGC%20497 | NGC 497 is a barred spiral galaxy approximately 336 million light-years away from Earth in the constellation of Cetus. It was discovered by French astronomer Édouard Stephan on November 6, 1882.
NGC 497 was imaged by Halton Arp and included in his Atlas of Peculiar Galaxies as Arp 8, under the category of 'split arm' galaxies.
See also
List of NGC objects (1–1000)
References
External links
SEDS
Barred spiral galaxies
Cetus
497
4992
915
8
Astronomical objects discovered in 1882
Discoveries by Édouard Stephan | NGC 497 | [
"Astronomy"
] | 112 | [
"Cetus",
"Constellations"
] |
55,921,429 | https://en.wikipedia.org/wiki/Julianna%20Lisziewicz | Julianna Lisziewicz (born 1959) is a Hungarian immunologist. Lisziewicz headed many research teams that have discovered and produced immunotheraputic drugs to treat diseases like cancer and chronic infections like HIV/AIDS. Some of these drugs have been successfully used in clinical trials.
Education
Lisziewicz graduated from Budapest University of Technology in Budapest, Hungary with an MSc in Chemistry and Biology in 1982. She went on to earn her Ph.D. in Molecular Biology at the Max-Planck Institute in Germany. Lisziewicz did post-doctoral research at the Max-Planck Institute of Experimental Medicine from 1985 to 1989.
Career
National Institutes of Health
Lisziewicz worked at the National Institutes of Health (NIH) from 1989 to 1995. During her time working at the National Cancer Institute she was the Head of the Antiviral Unit at the Laboratory of Tumor Cell Biology.
Research Institute for Genetic and Human Therapy (RIGHT)
In 1995, Lisziewicz and her colleague Franco Lori founded the Research Institute for Genetic and Human Therapy (RIGHT), where Lisziewicz worked as the Director. RIGHT is a non-profit organization based in the United States and Italy that funds research to develop immunologic technologies, create new therapies, and research vaccines for many chronic diseases like HIV/AIDS. RIGHT strives to quickly put their discoveries to use in patient treatments.
Genetic Immunity, Inc.
Lisziewicz founded Genetic Immunity, Inc., and worked as the President and the CEO of the company. Genetic Immunity is a private clinical-stage biotechnology company in the United States and Hungary. Genetic Immunity works to create and commercialize immunotherapeutic biologics to treat chronic viral infections, allergies, and cancers to prolong the life of the patient and improve their quality of life.
TREOS Bio
TREOS Bio is a company that develops precision vaccines to treat and prevent cancer using computational immune-oncology. Lisziewicz worked as the Chief Scientific Officer of TREOS Bio.
Research
Antisense oligonucleotides
While working at the National Institute of Health, Lisziewicz worked to find a gene therapy approach to treat HIV/AIDS. She based her research on discovering if small portions of gene-stopping DNA (called antisense oligonucleotides) could be created to bind up the viral RNA in retroviruses like HIV so that the virus could not make more copies of itself to continue the infection. Small pieces of messenger RNA (or mRNA) carry a copy of the cell's DNA to the ribosomes where the mRNA directs the ribosomes to create the proteins that the cells need. Viruses (like HIV) have their own set of mRNA, and they use the ribosomes of the cell they infected to make new viruses to propagate the infection throughout the body. Lisziewicz's idea was to create antisense oligonucleotides that are complementary to the HIV's viral mRNA. These complementary DNA pieces can bind to the HIV viral mRNA and prevent the HIV virus from replicating itself. The use of antisense oligonucleotides worked very well in cell cultures, and was quickly transferred to clinical trials.
DermaVir
DermaVir immunotherapy was created during Lisziewicz's research at the National Cancer Institute in Bethesda, Maryland. She worked to produce gene and antisense therapies to treat HIV/AIDS, and researched how the immune system controls HIV in tissue culture and in monkey models. She applied these results to the treatment of HIV patients in clinical trials. Lisziewicz discovered and headed the preclinical and clinical development of DermaVir HIV immunotherapy. Under Lisziewicz's direction, DermaVir successfully completed a Phase 2 clinical trial.
DermaVir is a topical vaccine that is applied with a patch to the skin. It is a new immunization strategy that uses dendritic cells to increase viral antigen production. DermaVir contains a plasmid that expresses all of the HIV proteins except integrase. This stimulates an immune response to attack the cells infected with HIV.
DermaVir has been proven safe and immunogenic in several clinical trials, one of which was in collaboration with the Division of AIDS (DAIDS). In one trial, Lisziewicz's research team compared the immunogenicity of topical-based and ex vivo dendritic cell-based DermaVir in rhesus macaques. As a result, it was discovered that both vaccinations induced CD4 helper T cells and CD8 memory T cells that are specific to simian immunodeficiency virus. The CD4 helper T cells and CD8 memory T cells were identified using an in vivo skin test and an in vitro intracellular cytokine-based assay. The topical DermaVir vaccine is an improvement upon the ex vivo dendritic cell- based immunization that could offer a new alternative therapy for patients with HIV.
PolyPEPI™
An investigation Lisziewicz was involved with when she was working at TREOS Bio is how human leukocyte antigen (HLA) genes regulate immune responses. This research led to the development of a computational immune-oncology technology that can determine a patient's natural T cell response to tumor antigens. As a result, TREOS Bio found there was a correlation between a patient's HLA gene sequence and how well their immunotherapies worked. PolyPEPI™ immunotherapies to treat a number of cancer indications were created by TREOS Bio using the computational immune-oncology.
Langerhans cell-targeting DNA vaccines
Langerhans cells are a natural agent of antigen release. They are the precursors of dendritic cells in the skin and mucosa. Lisziewicz and her team developed synthetic nanoparticles that act like pathogens and specially target Langerhans cells in epidermal cell cultures. When these nanoparticles are applied topically to human subjects, a strong immune response was observed. This vaccine has been clinically proven, and it opens the door for more new dendritic cell-targeting vaccines to be created for the treatment of cancers.
References
1959 births
Living people
Molecular biologists
Hungarian women physicians
Budapest University of Technology and Economics alumni
Women immunologists
Hungarian immunologists
Physicians from Budapest | Julianna Lisziewicz | [
"Chemistry"
] | 1,330 | [
"Molecular biologists",
"Biochemists",
"Molecular biology"
] |
55,925,977 | https://en.wikipedia.org/wiki/SV%20Centauri | SV Centauri is a variable star in the constellation Centaurus. An eclipsing binary, its visual apparent magnitude has a maximum of 8.71, fading to 9.98 during primary eclipse and 9.42 during secondary eclipse. From its brightness, it's estimated to be around away from Earth. Parallax measurements from Gaia Data Release 2 yield a similar distance of around . Henrietta Leavitt announced the discovery of this variable star, in 1906, when it was called CPD-59° 3809. It was given its variable star designation, SV Centauri, in 1907.
SV Centauri is a contact binary made of two hot B-type stars with spectral types of B1V and B6.5III and effective temperatures of 23,000 and 14,000 K. The primary component, the brighter star with 11,700 times the solar luminosity, is the less massive one with 7.7 times the solar mass and has a radius of 6.8 times the solar radius. The secondary component has a mass equal to 9.6 solar masses, radius of 7.4 solar radii and a brightness 1,900 times larger than the Sun's. The separation between the center of each star is only 15.3 solar radii. The system is viewed from a high inclination of 81.8°.
The orbital period of SV Centauri is monotonically decreasing at a very fast mean rate of 2.1 seconds per year, the largest rate for any known system. The first observations of the system, in 1894, revealed a period of 1.6606 days, which decreased to 1.6581 days in 1993, showing a decrease rate that is variable with time, but with time intervals of 10 to 30 years when it is constant. The transition between such intervals of constant change can be accompanied by very fast decreases in the period, such as of 15 seconds per year in 1975.
The most probable explanation for the period decrease is mass transfer from the less massive to the more massive star and subsequent mass loss through the L3 Lagrangian point of the system, which is located on the outer side of the more massive star. The mass loss causes loss of angular momentum, which is compensated by a decrease in the separation between the stars. In this model, the system is losing mass at a rate of about 5 solar masses per year; the variation of this rate causes the variation in the rate of period decrease. The alternative possibility is mass transfer from the more massive to the less massive star, which naturally tends to decrease the orbital period. This may create an accretion disk around the less massive star, similar to Beta Lyrae.
References
Centaurus
Centauri, SV
Beta Lyrae variables
B-type main-sequence stars
B-type giants
102552
Durchmusterung objects | SV Centauri | [
"Astronomy"
] | 584 | [
"Centaurus",
"Constellations"
] |
55,926,948 | https://en.wikipedia.org/wiki/Pesticide%20standard%20value | Pesticide standard values are applied worldwide to control pesticide pollution, since pesticides are largely applied in numerous agricultural, commercial, residential, and industrial applications. Usually, pesticide standard value is regulated in residential surface soil (i.e., pesticide soil regulatory guidance value, or RGV), drinking water (i.e., pesticide drinking water maximum concentration level, or MCL), foods (i.e., pesticide food maximum residue level, or MRL), and other ecological sections (e.g., air, surface water, groundwater, bed sediment, or aquatic organisms).
Definition
Pesticide standard values specify the maximum amount of a pollutant that may be present without prompting some form of regulatory response such as human health and ecological effects. Pesticide standard values are often derived from laboratory toxicology data (i.e., animal tests), human or ecological parameters (i.e., body weight, intake rate, lifetime, etc.), and human health risk models such as USEPA and RIVM models. On the other hand, the European Union took a precautionary approach (in accordance with the principles of its environmental policy) before toxicological data was available and provided very strict and protective standards for all pesticides in drinking water.
Worldwide pesticide standard values
Up till now (November 2017), less than 30% of the worldwide nations have regulated pesticide standard values in surface residential soil, about 50% of the total nations have provided pesticide standard values in drinking water and agricultural foods. Many nations in Africa, Asia, and South America are lacking pesticide standard values for the major human and ecological exposure pathways such as soil, sediment, and water.
Pesticide standard values for many current and historical largely used pesticides such as DDT, aldrin, lindane, glyphosate, MCPA, chlorpyrifos, and 2,4-D often vary over seven, eight, or nine orders of magnitude and are log-normally distributed, which indicates that there is little agreement on the regulation of pesticide standard values among worldwide jurisdictions. Additionally, many worldwide pesticide standard values are not sufficiently low to protect public health based on human health risk uncertainty bounds calculations and maximum legal contribution estimations.
See also
Persistent organic pollutant
Aquatic toxicology
Regulation of pesticides in the European Union
Pesticide regulation in the United States
References
Pollution control technologies
Pesticides
Environmental effects of pesticides
Environmental standards | Pesticide standard value | [
"Chemistry",
"Engineering",
"Biology",
"Environmental_science"
] | 507 | [
"Pesticides",
"Toxicology",
"Pollution control technologies",
"Environmental engineering",
"Biocides"
] |
55,927,187 | https://en.wikipedia.org/wiki/NGC%20725 | NGC 725 is a spiral galaxy approximately 450 million light-years away from Earth in the constellation of Cetus. It was discovered by Francis Preserved Leavenworth on November 9, 1885 with the 26" refractor at the Leander McCormick Observatory.
See also
Spiral galaxy
List of NGC objects (1–1000)
Cetus (constellation)
References
External links
SEDS
Spiral galaxies
Cetus
725
6950
Astronomical objects discovered in 1885
Discoveries by Francis Leavenworth | NGC 725 | [
"Astronomy"
] | 95 | [
"Cetus",
"Constellations"
] |
55,927,722 | https://en.wikipedia.org/wiki/NGC%207259 | NGC 7259 is a spiral galaxy approximately 66 million light-years away from Earth in the constellation of Piscis Austrinus. It was discovered by John Herschel on September 28, 1834.
SN 2009ip
In 2009, a possible supernova was detected within the galaxy, and was designated SN 2009ip. Since the brightness faded in a matter of days, it was redesignated as a luminous blue variable (LBV) supernova impostor.
During the following years several luminous outbursts were detected from SN 2009ip. In September 2012 SN 2009ip was classified as a young type IIn supernova.
See also
List of NGC objects (7001–7840)
Piscis Austrinus (constellation)
References
External links
SEDS
Spiral galaxies
Piscis Austrinus
7259
68718
Astronomical objects discovered in 1834
Discoveries by John Herschel | NGC 7259 | [
"Astronomy"
] | 179 | [
"Piscis Austrinus",
"Constellations"
] |
55,928,064 | https://en.wikipedia.org/wiki/SN%202009ip | SN 2009ip was a supernova discovered in 2009 in the spiral galaxy NGC 7259 in the constellation of Piscis Austrinus. Since the brightness waned after days post-discovery, it was redesignated as Luminous blue variable (LBV) Supernova impostor.
During the following years several luminous outbursts were detected from the SN 2009ip. In September 2012 SN 2009ip was classified as a young type IIn supernova.
References
Further reading
External links
Light curves and spectra on the Open Supernova Catalog
Supernova 2009ip in NGC 7259 Rochester Academy of Science
Supernovae
Astronomical objects discovered in 2009
Piscis Austrinus
Luminous blue variables | SN 2009ip | [
"Chemistry",
"Astronomy"
] | 138 | [
"Piscis Austrinus",
"Supernovae",
"Astronomical events",
"Constellations",
"Explosions"
] |
55,928,290 | https://en.wikipedia.org/wiki/Glass%20bead%20road%20surface%20marking | Glass beads composed of soda lime glass are essential for providing retroreflectivity in many kinds of road surface markings. Retroreflectivity occurs when incident light from vehicles is refracted within glass beads that are imbedded in road surface markings and then reflected back into the driver's field of view. In North America, approximately 227 million kilograms of glass beads are used for road surface markings annually. Roughly 520 kilograms of glass beads are used per mile during remarking of a five lane highway system, and road remarking can occur every two to five years. In the United States, the massive demand for glass beads has led to importing from countries using outdated manufacturing regulations and techniques.
These techniques include the use of heavy metals such as arsenic, antimony, and lead during the manufacturing process as decolorizes and fining agents. It has been found that the heavy metals become incorporated into the bead's glass matrix and may leach under environmental conditions that roads experience.
Composition and manufacturing
The synthesis of these beads begins when calcium carbonate is heated to anywhere from 800 to 1300C. This heating causes a decomposition reaction which forms solid calcium oxide and releases carbon dioxide gas.
CaCO3 ->[{800-1300C}]{CaO(s)} + CO2(g)
Similarly, sodium carbonate decomposes to sodium oxide and releases carbon dioxide gas.
Na2CO3 -> [{800-1300C}] {Na2O(s)} + CO2(g)
Sodium oxide is then reacted with silica to produce sodium silicate liquid glass.
{Na2O(s)}+SiO2(s) -> Na2SiO3(l)
Lastly, to complete the general structure of the soda-lime glass, calcium oxide is dissolved in solution with sodium silicate glass, which ultimately reduces the softening temperature of the glass. Additional metals and ions are added to this melted glass to improve its properties, and the compound is then sprayed and formed into beads using either the direct or indirect method.
{Na2SiO3(l)}+ CaO(s) -> Na2O*CaO*SiO2
Overall, the percent composition of major compounds found in the final glass bead product is shown below.
In addition to these primary components of soda-lime glass, manufacturers include heavy metals arsenic, antimony, and lead to refine and improve the properties of the glass bead. Lead in the form of PbO is added to increase the durability of the glass to withstand harsh road conditions. Arsenic and antimony are used as fining agents that facilitate the removal of gas bubbles from the molten mixture. Carbon dioxide produced by the decomposition of calcium carbonate and sodium carbonate is removed to obtain the required retroreflective properties of the glass. In addition, both arsenic and antimony are used as decolorizers. Having a colorless glass is crucial to maximizing retroreflectivity. Arsenic in its inorganic form assists in the decolorization of the glass by controlling iron's oxidation state. Arsenic oxidizes ferrous oxide to its less colorful counterpart, ferric oxide.{As2O5}+4Fe3O4->{As2O3} + 6Fe2O3
Antimony in the form of Sb2O5 performs a similar reaction as arsenic, oxidizing ferrous oxide to ferric oxide.
{Sb2O5} + 4Fe3O4 -> {Sb2O3}+6Fe2O3
While these three heavy metals can typically be found in both domestic and imported glass beads, they vary in concentration. According to the US Environmental Protection Agency, the Resource Conservation and Recovery Act limits the levels of heavy metal content in accordance with their toxicity. Due to increasing demands for marked roads, however, the majority of glass beads used in the U.S. are imported from countries with little to no regulation on heavy metal content. For example, beads obtained from North America contain approximately 15 mg of arsenic per kg of beads, while some from China have concentrations of up to 1000 mg/kg. Imported bead concentrations of each of these metals are listed in the table below.
Degradation of glass beads
Environmental conditions can cause degradation of glass beads, leading to release of incorporated heavy metals into the environment. While abrasion may dislodge these beads from the road marking itself, the reaction of these beads with an aqueous environment vastly accelerate their decomposition and heavy metal release.
There are three reactions involved in the corrosion of silicon dioxide. The first is an ion exchange reaction, in which mobile ions of a solution are exchanged for those of similar charge on the solid. Particularly, this reaction is involving cation exchange material, where a negatively charged structural backbone allows the replacement of positively charged cations. This reaction involved in the degradation of soda lime beads shows various ions that are interaction with the silicon-oxygen network (e.g. Na+, Ca^2+, K+, Mg^2+) being replaced with a hydrogen ion.
{{Si-O^-} Na+} + ({H^+} + OH^-) -> {Si-OH} + {Na+} +OH-
In addition to this reaction, a hydroxyl ion can attack the Si-O bond causing dissolution of the SiO2 matrix and creating silanol and non-bridging oxygen groups.
{Si-O-Si} + {OH^-} -> {Si-OH} + {^-O-Si}
As dissolution occurs, the non-bridging oxygen groups can abstract hydrogen ions from solution.
{Si-O^-} + ({H^+} + OH^-) -> {Si-OH}+{OH^-}
An increase in the concentration of hydroxyl ions comes with increased alkalinity of the aqueous solution. This increase in pH has shown, in varying column leaching studies, to increase the reduction potential and DOC (dissolved organic carbon) concentration of the solution. This ultimately leads to an increase in mobility of many metals including arsenic, copper, and nickel.
The mobility of these heavy metals are therefore affected by the presence of alkali oxides. The Na+, Ca^2+, Mg^2+, and K+ ions can associate with the tetrahedral networks of silicon and oxygen, forming a trigonal antiprism network. In trigonal antiprism formation, the ions coordinate with three oxygen atoms at a distance of 2.3 angstroms and then another three oxygen atoms at a nonbonding distance of 3 angstroms. As the concentration of alkali oxides increases in metal beads, the probability of chemical attack increases due to the more open and accessible glass chemical network and structure.
Heavy metal speciation and leaching
During both routine road marking removal and harsh environmental conditions, these glass beads can degrade and leach incorporated heavy metals. Although the exact mechanism of heavy metal incorporation into the glass beads is unknown, current literature hypothesizes that the heavy metals are associated with alkali and alkali earth metals on the surface of glass beads. Environmental conditions relevant to road surfaces such as pH, different salts, and ionic strength strongly influence the leaching process. In particular, pH determines the speciation of the heavy metal which is critical for solubility in the aqueous phase. The following graphs show the speciation of heavy metals as a function of pH.
Few states have regulations on leached concentrations of heavy metals. For example, New Jersey limits arsenic to 3 μg/L, lead to 65 μg/L, and antimony to 78 μg/L. In studies that subjected batches of glass beads to environmental conditions in a lab setting, 96% of the leached concentrations of arsenic exceeded 3 μg/L, 75% of leached lead exceeded 65 μg/L, and 27% of the leached concentrations of antimony exceeded the criterion of 78 μg/L. The following graphs show the total concentrations of heavy metals leached from glass beads after 160 days as a function of pH, salt type, and ionic strength.
Interaction with roadside soil
Once the arsenic is mobilized in aqueous form, humic substances interact with arsenic. It has been shown that particularly under acidic environments, humic acids contribute immensely to the retention of arsenic in the soil matrix. While an exact mechanism for this has not been confirmed, it has been hypothesized that humic acids are acting as anion exchange moieties, potentially through amine interaction within the humic material with arsenic. This is only likely if the amine is quaternary, thus justifying the low pH claim, as similar resins are used to separate As(III) and As(V). Another possible mechanism of arsenic's interaction with humic substances is through metal complexes. Potentially, arsenic adsorption could occur as a humic-acid-metal-As bridging ligand, or possibly adsorbed to the clay that is bound to the humic acid itself as well.
Lead, on the other hand, has been shown to increase binding to humic substances with increasing pH and decreasing ionic strength. Research has indicated that monodentate lead binds at a relatively high measure to carboxylic type groups present in humic materials. There is also evidence of the bidentate form of lead binding to phenolic-type groups in the ortho position in humic material when concentrations of lead are high, as is the case for soils nearby marked roads.
In the case of antinomy, qualitative studies on its association with humic substances is scarce and rarely conclusive. It has been shown in many cases, however, that pH has little indication on these interactions. One study indicated that organic ligands that possess carboxylic groups or hydroxyl groups create stable bidentate chelates in its speciation as As(III) and As(V). Another indicated that As(III) when bound to humic material is easily oxidized, and can be released back into aqueous solution as (SbOH)6-, thus showing that As(V) is more commonly bound to humic material. The details of how this binding occurs mechanistically remains relatively unresolved, but knowledge of the primary form of its binding is important to furthering this research.
Alternative to heavy metal usage
Retroreflectivity is essential to safe driving conditions. While metals are necessary to achieve these goals, there are other, non-toxic metals that can achieve the same results. These may include zirconium, tungsten, titanium, and barium. The amount of these metals that could be incorporated into the glass varies based on its country of origins and the regulations placed on those countries, but further research on alternatives to heavy metal usage in road markings would assist in reducing heavy metal leachate near roadside soils.
See also
Road surface marking
Toxic heavy metal
References
External links
U.S. Federal Highway Administration—Learn About Pavement Markings
Road surface markings | Glass bead road surface marking | [
"Physics",
"Chemistry",
"Materials_science",
"Engineering",
"Environmental_science"
] | 2,280 | [
"Glass engineering and science",
"Environmental chemistry",
"Transport and the environment",
"Materials science",
"Physical systems",
"Transport",
"Soil contamination"
] |
51,488,917 | https://en.wikipedia.org/wiki/Glycoside-pentoside-hexuronide%3Acation%20symporter%20family | The Glycoside-Pentoside-Hexuronide (GPH):Cation Symporter Family is part of the major facilitator superfamily and catalyzes uptake of sugars (mostly, but not exclusively, glycosides) in symport with a monovalent cation (H+ or Na+). The various members of the family have been reported to use Na+, H+ or Li, Na+ or Li+, or all three cations as the symported cation.
Structure
Proteins of the GHP family are generally about 500 amino acids in length, although the Gram-positive bacterial lactose permeases are larger, due to a C-terminal hydrophilic domain that is involved in regulation by the phosphotransferase system. All of these proteins possess twelve putative transmembrane α-helical spanners.
Homology
Homologues are from bacteria, including the distantly related sucrose:H+ symporters of plants and a yeast maltose/sucrose:H+ symporter of Schizosaccharomyces pombe. This yeast protein is about 24% identical to the plant sucrose:H+ symporters and is more distantly related to the bacterial members of the GPH family. Limited sequence similarity of some of these proteins with members of the major facilitator superfamily has been observed, and their 3D structures are clearly similar.
Transport Reaction
The generalized transport reaction catalyzed by the GPH:cation symporter family is:
Sugar (out) + [H+ or Na+] (out) → Sugar (in) + [H+ or Na+] (in)
References
Protein families
Membrane proteins
Transmembrane proteins
Transmembrane transporters
Transport proteins
Integral membrane proteins | Glycoside-pentoside-hexuronide:cation symporter family | [
"Biology"
] | 389 | [
"Protein families",
"Protein classification",
"Membrane proteins"
] |
51,488,947 | https://en.wikipedia.org/wiki/Faraday%20House | Faraday House Electrical Engineering College was created to train engineers in power generation and distribution. It was set up at a time before engineering was widely taught at universities, founded as an adjunct to a commercial company for supplying towns with electricity. It operated between 1890 and 1967, mainly at Southampton Row, London. Six of its alumni have been presidents of the Institution of Electrical Engineers.
The Faraday House curriculum covered the whole electrical field, at a level less theoretical than the City and Guilds Institute at South Kensington, with the four-year course of study resulting in a D.F.H. (Diploma of Faraday House). The first year was spent at the college, then eight months at a mechanical engineering works, followed by five more terms at the college, and finally a period spent as a graduate apprentice at an electrical engineering works. Examinations were supervised by the Institution of Electrical Engineers, and two senior scholarships were offered; the Faraday (75 guineas per annum), and the Maxwell (40 guineas per annum).
At a 1992 symposium held in his honour, the microscopist Vernon Ellis Cosslett, who lectured at the college from 1935 to 1939, during an interview with Tom Mulvey, of the Department of Electronic Engineering and Applied Physics at Aston University, Birmingham, related: "... Faraday House... an 'Engineering College for the sons of Gentlemen'... was set up in the 1880s before electrical engineering was respectable at universities; the engineering industry set it up on their own account and funded it themselves. They had a grand man in charge, one Alexander Robinson, a man of some eminence... running the thing very well at a level we would now call HNC, Higher National Certificate, Higher National Diploma level."
The building has been occupied by Syracuse University's study abroad program since 2005.
References
1890 establishments in England
1967 disestablishments in England
Defunct universities and colleges in London
Educational institutions established in 1890
Electrical engineering departments
Engineering education in the United Kingdom
Syracuse University buildings | Faraday House | [
"Engineering"
] | 415 | [
"Electrical engineering organizations",
"Electrical engineering departments",
"Engineering universities and colleges"
] |
51,489,296 | https://en.wikipedia.org/wiki/ATP%3AADP%20antiporter%20family | The ATP:ADP Antiporter (AAA) Family (TC# 2.A.12) is a member of the major facilitator superfamily. Members of the AAA family have been sequenced from bacteria and plants.
Structure and function
One protein from the obligate intracellular bacterial parasite, Rickettsia prowazekii, is of 498 amino acyl residues, and is believed to span the membrane 12 times. The transporter is an obligate exchange translocase specific for ATP and ADP. It functions to take up ATP from the eukaryotic cell cytoplasm into the bacterium in exchange for ADP. The ATP/ADP uniporters can also transport inorganic phosphate, but not ribonucleoside and monophosphates, as well as deoxyribonucleotides.
Transport reaction
The transport reaction catalyzed by the antiporters is:
ATP (out) + ADP (in) ⇌ ATP (in) + ADP (out)
Homology
The AAA family proteins are distantly related to members of the major facilitator superfamily, and are not related to the mitochondrial ATP/ADP exchangers of the mitochondrial carrier family which pump ATP out of mitochondria in accordance with the polarity of the mitochondrial membrane potential.
References
Protein families
Membrane proteins
Transmembrane proteins
Transmembrane transporters
Transport proteins
Integral membrane proteins | ATP:ADP antiporter family | [
"Biology"
] | 296 | [
"Protein families",
"Protein classification",
"Membrane proteins"
] |
51,493,917 | https://en.wikipedia.org/wiki/NGC%20163 | NGC 163 is an elliptical galaxy in the constellation Cetus. It was discovered by William Herschel in 1890. Seen through an optical telescope it ranges up to 13th magnitude.
Notes
References
External links
Cetus
Elliptical galaxies
0163
002149 | NGC 163 | [
"Astronomy"
] | 50 | [
"Cetus",
"Constellations"
] |
51,493,998 | https://en.wikipedia.org/wiki/NGC%20164 | NGC 164 is a spiral galaxy located in the constellation Pisces. It was found by the German astronomer Albert Marth on 3 August 1864.
References
External links
SEDS
0164
02181
Pisces (constellation)
Spiral galaxies | NGC 164 | [
"Astronomy"
] | 49 | [
"Pisces (constellation)",
"Constellations"
] |
51,494,005 | https://en.wikipedia.org/wiki/Zhiwei%20Yun | Zhiwei Yun (; born September 1982) is a Chinese-born American mathematician and writer. He is a Professor of Mathematics at MIT specializing in number theory, algebraic geometry and representation theory, with a particular focus on the Langlands program.
He was previously a C. L. E. Moore instructor at Massachusetts Institute of Technology from 2010 to 2012, assistant professor then associate professor at Stanford University from 2012 to 2016, and professor at Yale University from 2016 to 2017.
Education
Yun was born in Changzhou, China. As a high schooler, he participated in the International Mathematical Olympiad in 2000; he received a gold medal with a perfect score. Yun received his bachelor's degree from Peking University in 2004. In 2009, he received his Ph.D. from Princeton University, under the direction of Robert MacPherson.
Work
His collaborations with Wei Zhang, Xinyi Yuan and Xinwen Zhu have received attention in publications such as Quanta Magazine and Business Insider. In particular, his work with Wei Zhang on the Taylor expansion of L-functions is "already being hailed as one of the most exciting breakthroughs in an important area of number theory in the last 30 years."
Yun also made substantial contributions towards the global Gan–Gross–Prasad conjecture.
Awards
Yun was awarded the SASTRA Ramanujan Prize in 2012 for his "fundamental contributions to several areas that lie at the interface of representation theory, algebraic geometry and number theory."
In December 2017, he was awarded the 2018 New Horizons In Mathematics Prize together with Wei Zhang, Aaron Naber and Maryna Viazovska.
He was included in the 2019 class of fellows of the American Mathematical Society "for contributions to geometry, number theory, and representation theory, including his construction of motives with exceptional Galois groups". In 2019 he received the Morningside Medal jointly with Xinwen Zhu.
Selected publications
(with Davesh Maulik)
(with Roman Bezrukavnikov)
(with Ngô Bảo Châu and Jochen Heinloth)
(with Alexei Oblomkov)
(with Wei Zhang)
References
1982 births
Living people
21st-century Chinese mathematicians
21st-century Chinese science writers
Educators from Changzhou
Fellows of the American Mathematical Society
International Mathematical Olympiad participants
Massachusetts Institute of Technology School of Science faculty
Mathematicians from Jiangsu
Number theorists
Peking University alumni
Princeton University alumni
Recipients of the SASTRA Ramanujan Prize
Scientists from Changzhou
Writers from Changzhou | Zhiwei Yun | [
"Mathematics"
] | 490 | [
"Number theorists",
"Number theory"
] |
51,494,017 | https://en.wikipedia.org/wiki/NGC%20165 | NGC 165 is a barred spiral galaxy located in the constellation Cetus. It was discovered in 1882 by Wilhelm Tempel and was described by as "faint, large, star in centre, eastern of 2" by John Louis Emil Dreyer.
One supernova has been observed in NGC 165: SN2021acnz (typeIb, mag. 19.2).
References
External links
0165
Barred spiral galaxies
Cetus | NGC 165 | [
"Astronomy"
] | 88 | [
"Cetus",
"Constellations"
] |
51,494,308 | https://en.wikipedia.org/wiki/NGC%20166 | NGC 166 (also known as PGC 2143) is a spiral galaxy located around 2.6 million light-years away in the constellation Cetus, with an apparent magnitude of 15.18. It was discovered by Francis Preserved Leavenworth in 1886.
See also
Spiral galaxy
List of NGC objects (1–1000)
Cetus (constellation)
References
External links
SEDS
Astronomical objects discovered in 1886
Cetus
0166
002143
Discoveries by Francis Leavenworth
Spiral galaxies | NGC 166 | [
"Astronomy"
] | 97 | [
"Cetus",
"Constellations"
] |
51,494,341 | https://en.wikipedia.org/wiki/Premature%20thelarche | Premature thelarche (PT) is a medical condition, characterised by isolated breast development in female infants. It occurs in females younger than 8 years, with the highest occurrence before the age of 2. PT is rare, occurring in 2.2-4.7% of females aged 0 to 2 years old. The exact cause of the condition is still unknown, but it has been linked to a variety of genetic, dietary and physiological factors.
PT is a form of Incomplete Precocious Puberty (IPP). IPP is the presence of a secondary sex characteristic in an infant, without a change in their sex hormone levels. Central Precocious Puberty (CPP) is a more severe condition than IPP. CPP is the presentation of secondary sex characteristics, with a change in sex hormones due to alteration of the hypothalamic-pituitary-gonadal (HPG) axis.
CPP is an aggressive endocrine disorder with harmful developmental consequences for the patient. At the presentation of PT, diagnostics are used to ensure it is not early stage CPP. CPP can be differentiated from PT through biochemical testing, ultrasounds and ongoing observation. There is no treatment for PT but regular observation is important to ensure it does not progress to CPP. CPP diagnosis is important as treatment is necessary.
Symptoms and signs
Premature thelarche is breast hypertrophy before puberty. This form of hypertrophy is an increase in breast tissue. PT occurs in pre-pubescent females, under the age of 8, having a peak occurrence in the first two years of life. The breast development is usually bi-lateral: both breasts show development. In some cases development may be unilateral: one breast develops.
Patterns of PT
There are four patterns of PT development. Most patients have hypertrophy followed by complete loss of the excess breast tissue (51% of cases) or loss of most excess tissue, but some remains until puberty (36% of cases). Less commonly patients have ongoing patterns of thelarche: 9.7% suffer from a cyclic pattern where the size of the breast tissue varies over time, and 3.2% experience continual increase in tissue size.
Associated Symptoms
The main symptom of PT is enlarged breast tissue in infants. estrogen's role in PT, also leads to increased bone age and growth in some cases. In PT these secondary symptoms are minimal: bone age only varies from actual age by a few months and growth velocity only slightly varies from the norm. Diagnostic tests will distinguish these PT secondary symptoms from the more severe bone aging and growth occurring in early CPP.
Pathophysiology
The direct pathophysiology behind PT is still unknown, but there are many postulated causes.
Estrogen
PT is linked to increased sensitivity of the breast tissue to estradiol, an estrogen derivative, in certain prepubertal individuals. Sporadic estrogen or estradiol production in the adrenal glands, follicles or ovarian cysts is also linked to the condition.
Follicle stimulating hormone
Follicle Stimulating Hormone (FSH) is secreted from the anterior pituitary. FSH plays a key role in development, growth and puberty, thus it is suspected to play a role in PT. Gondotropin-releasing hormone (GnRH) stimulation testing in some patients with PT has shown a dominant response from FSH. This response is linked to active mutations in the FSH receptor and Gs-a subunit in PT. Genetic investigation indicated these mutations only account for few cases of premature PT. PT may also be caused by transient partial activation of the HPG axis. Partial activation would release a surplus of FSH from the anterior pituitary without further disruption of the HPG axis.
Other causes
The consumption or exposure to certain endocrine disrupters have also been linked to PT.
CPP and PT
PT is the benign growth of breasts in infants, while CPP is a condition that involves the frequent activation of the HPG axis in patients. PT does not require treatment, as the condition is limited to enlarged breast tissue that usually subsides with time. CPP is associated with a wider range of symptoms including thelarche, pubic hair growth, accelerated bone aging, increased growth velocity and early epiphyseal growth. If an individual is affected with CPP they will need to begin treatment immediately. CPP is treated with lutenizing hormone (LH) releasing hormone agonists. PT can impact growth velocity and bone age slightly, but CPP affects these characteristics to the point of detriment to the adult stature. Patients with suspected PT must undergo diagnostic testing to ensure it isn’t CPP or exaggerated thelarche, the intermediate stage before CPP.
Notable hormone differences occur between CPP and PT patients, so studying these hormone levels is the main biochemical diagnostic used in CPP. Individuals with CPP usually have a higher basal LH levels and LH:FSH ratios.
Few PT patients, 9 to 14%, are predicted to develop CPP. Observation allows clinicians to identify the presentation of CPP indicative symptoms in PT patients. No diagnostics tests can indicate if a PT patient is at risk of developing CPP.
Diagnosis
Premature thelarche does not require treatment. In PT, breast hypertrophy will usually stop completely and patients will experience regression of the breast tissue over 3 to 60 months. Less commonly, patients may remain with residual breast tissue or continue through cycles of breast hypertrophy and regression until puberty.
Diagnostics are utilised in individuals with PT, especially at the presentation of other secondary sex characteristics. Diagnostics aim to ensure PT patients are not suffering from CPP.
Pelvic Ultrasounds
Pelvic ultrasounds are important in diagnosing CPP. Patients with CPP have an increased ovary and uterus size. The ovary and uterus volume of CPP patients is similar to that of females undergoing puberty. The pelvis ultrasound is problematic as a diagnostic, as there is not a specific cut-off for the uterine and ovary volumes that indicate the patient has CPP. Patients with PT should have a uterine and ovarian volume within the normal range for their age. Pelvic ultrasounds are a desirable diagnostic as they are non-invasive and easy to continually review. The pelvic ultrasound should be paired with biochemical tests to determine the presence of CPP.
Biochemical tests
Biochemical tests study the hormone levels in patients. CPP patients have elevated LH levels and peak LH:FSH ratios when compared to PT patients. It is hard to use LH as a diagnostic for CPP, as the LH assay has varying sensitivity and specificity. The GnRH stimulation test is the main diagnostic biochemical test used to distinguish PT from CPP. The GnRH test demonstrates the pituitary responsiveness to GnRH. GnRH stimulates the release of LH and FSH from the anterior pituitary. The peak LH:FSH ratio in CPP patients is similar to the ratio of pubertal females. Females with PT demonstrated a LH:FSH ratio lower than pubertal females. The disadvantages of the GnRH stimulation test is it takes a long time to perform and requires multiple collections from the patient, making the process time consuming and inconvenient. The test is highly specific but has low sensitivity as the LH hormone response is usually observed in later stages of CPP. There are also overlaps in the expected value in the GnRH test results of individuals with CPP and PT.
Combined diagnostic approach
The diagnostic inconsistency in CPP means that a combination of all of pelvic ultrasounds and biochemical tests should be paired with observation, to ensure PT doesn’t progress to CPP.
Research
Exposure to environmental agents
Natural commodities like fennel, lavender and tea tree oils have been linked to PT. Lavender and tea tree oil have weak estrogenic activities. These estrogenic properties may cause an imbalance in endocrine signalling pathways, leading to PT in regular users of these products. Fennel tea has been studied as an endocrine disrupter linked to PT. Fennel seed oil contains anethole a compound with estrogenic effects. The tea contains fennel seed oil and regular use results in increased estradiol levels in the infant. Infants with fennel tea related PT, were given the tea as a homeopathic remedy for restlessness. The tea was consumed for at least four months before the presentation of PT symptoms. PT resulting from fennel tea subsides approximately six months after stopping the use of fennel tea.
Leptin
Leptin is an adipocyte hormone that has important implications of puberty and sex hormone secretion. Increased leptin has been linked to estrogen and estradiol secretion. Leptin has key roles in maintaining age appropriate body composition and desired weight. Leptin receptors are also found in mammary epithelial cells and leptin has been observed as a growth factor in breast tissue. Increased leptin levels have been observed in some cases of PT. The increase in leptin levels cause increased estradiol levels and development of breast tissue.
GNAS1 gene mutation
The form of PT with fluctuating hypertrophy in patients has been linked to activating mutations in the GNAS1 gene. This mutation accounts for a small number of cases of PT.
See also
Mammoplasia
Breast hypertrophy
Gynecomastia
References
External links
Breast diseases
Developmental biology
Human female endocrine system
Pediatrics
Rare diseases
Endocrine diseases
Premature events | Premature thelarche | [
"Biology"
] | 1,998 | [
"Behavior",
"Developmental biology",
"Reproduction"
] |
51,494,441 | https://en.wikipedia.org/wiki/NGC%20167 | NGC 167 is a spiral galaxy located approximately 172 million light-years from the Solar System in the constellation Cetus. It was discovered in 1886 by Francis Preserved Leavenworth.
See also
List of NGC objects (1–1000)
References
External links
SEDS
0167
2122
Cetus
Spiral galaxies
Discoveries by Francis Leavenworth | NGC 167 | [
"Astronomy"
] | 68 | [
"Cetus",
"Constellations"
] |
51,494,628 | https://en.wikipedia.org/wiki/ZFOURGE | ZFOURGE or the FourStar Galaxy Evolution Survey is a medium-band imaging survey that aims to establish an observational benchmark of galaxy properties at redshift z > 1. The survey uses an efficient near-infrared FOURSTAR instrument on the Magellan Telescopes, surveying in all three HST legacy fields: COSMOS, CDFS, and UDS.
Aims
ZFOURGE aims to create a benchmark of properties at z > 1 by deriving 1-2% accurate redshifts of ~60,000 galaxies at 1 < z < 3.
The majority of L∗ galaxies are too faint for spectroscopy. This resulted in inaccurate broadband photometric redshifts in earlier studies. FourStar is equipped with innovative "medium-bandwidth" filters from 1 − 1.8μm, which enable redshifts to z = 3.5.
This allows ZFOURGE to observe galaxy samples from the low mass at z > 1, to measure the value of mass and environment in transformation of galaxies, measure galaxy scaling relations. It will also explore the shape of the stellar mass function to z = 3, find luminous galaxies at z = 6–9, and identify high-redshift 1.5 < z < 2.5 (proto)clusters.
Instruments
The Fourstar ZFOURGE is conducted using the FourStar imager on the 6.5m Magellan Baade telescope at Las Campanas Observatory. It uses medium-band filters in the near-IR that allow for samplings at wavelengths that bracket the Balmer break of galaxies leading to more well-constrained photometric redshifts at 1 < z < 4 than with broadband filters alone. This dataset provides a comprehensive sampling of the 0.3 – 8 micron spectral energy distribution of galaxies.
ZFOURGE is composed of three 11′ x 11′ pointings with coverage in the CDFS, COSMOS and UDS. The 5sigma depth in a circular aperture of D=0.6" in the Ks band is 26.2-26.5 in the CDFS, COSMOS and UDS fields respectively at a typical seeing of ~0.4″.
References
External links
ZFOURGE Homepage
Astronomical surveys
Great Observatories program | ZFOURGE | [
"Astronomy"
] | 463 | [
"Astronomical surveys",
"Works about astronomy",
"Space telescopes",
"Astronomical objects",
"Great Observatories program"
] |
51,494,644 | https://en.wikipedia.org/wiki/NGC%20168 | NGC 168 is a lenticular galaxy located in the constellation Cetus. It was discovered in 1886 by Frank Muller.
References
External links
0168
Lenticular galaxies
Cetus
002192 | NGC 168 | [
"Astronomy"
] | 40 | [
"Cetus",
"Constellations"
] |
51,494,830 | https://en.wikipedia.org/wiki/NGC%20169 | NGC 169 is an unbarred spiral galaxy located in the constellation Andromeda. It was discovered on September 18, 1857, by R. J. Mitchell.
NGC 169 has a smaller companion named NGC 169A, also designated IC1559. The two are currently interacting, and the pair is included in Halton Arp's Atlas of Peculiar Galaxies.
References
External links
0169
00365
02202
282
Unbarred spiral galaxies
Interacting galaxies
Andromeda (constellation) | NGC 169 | [
"Astronomy"
] | 101 | [
"Andromeda (constellation)",
"Constellations"
] |
51,495,660 | https://en.wikipedia.org/wiki/XMASS | XMASS is a multipurpose physics experiment in Japan. It is a large cryogenic storage dewar, a tank of liquid xenon equipped with photosensors monitoring flashes of light that might be caused by interactions with hypothetical dark matter particles. Unlike a cryogenic particle detector, it operates at temperatures relatively far from absolute zero (specifically, ). In addition to searching for dark matter, XMASS is also studying neutrinoless double beta decay and solar neutrinos. The project is conducted by a team at Institute for Cosmic Ray Research, University of Tokyo.
Its results have not confirmed the annual variation seen in some earlier experiments.
History
Construction started in April 2007. The detector was completed in September 2010. Commissioning run was conducted between October 2010 and June 2012. Scientific data taking begun in November 2013. The detector is sometimes called XMASS-I, as it is planned to be superseded by an upgrade called XMASS-1.5 (a 5-ton detector) and eventually XMASS-II (24 ton detector).
The XMASS-I experiment shut down and ceased data taking 20 February 2019.
Results were published in 2021.
Detector
The detector is located 1000m underground in the Kamioka Observatory in Japan. It contains about 800 kg of xenon.
See also
References
External links
Direct Dark Matter Search by Annual Modulation [Results from XMASS] Sept 2015
dark matter
experiments for dark matter search
research in Japan | XMASS | [
"Physics",
"Astronomy"
] | 298 | [
"Dark matter",
"Unsolved problems in astronomy",
"Concepts in astronomy",
"Unsolved problems in physics",
"Experiments for dark matter search",
"Exotic matter",
"Physics beyond the Standard Model",
"Matter"
] |
51,495,665 | https://en.wikipedia.org/wiki/Steroidal%20antiandrogen | A steroidal antiandrogen (SAA) is an antiandrogen with a steroidal chemical structure. They are typically antagonists of the androgen receptor (AR) and act both by blocking the effects of androgens like testosterone and dihydrotestosterone (DHT) and by suppressing gonadal androgen production. SAAs lower concentrations of testosterone through simulation of the negative feedback inhibition of the hypothalamus. SAAs are used in the treatment of androgen-dependent conditions in men and women, and are also used in veterinary medicine for the same purpose. They are the converse of nonsteroidal antiandrogens (NSAAs), which are antiandrogens that are not steroids and are structurally unrelated to testosterone.
Medical uses
SAAs are used in clinical medicine for the following indications:
Prostate cancer in men
Benign prostatic hyperplasia in men
Androgen-dependent skin and hair conditions like acne, hirsutism, seborrhea, and pattern hair loss (androgenic alopecia) in women
Hyperandrogenism, such as due to polycystic ovary syndrome or congenital adrenal hyperplasia, in women
As a component of hormone therapy for transgender women
Precocious puberty in boys
Hypersexuality and paraphilias in men and sex offenders
Priapism in men
Available forms
Pharmacology
Unlike NSAAs, most SAAs show off-target hormonal activity such as progestogenic, glucocorticoid, or antimineralocorticoid activity, possess antigonadotropic effects, and are weak partial agonists of the AR with some capacity to activate the receptor. Due to their antigonadotropic effects, SAAs lower androgen levels in addition to directly blocking the actions of androgens at the AR; at sufficiently high dosages, they are able to lower circulating testosterone levels by up to 70 to 80% in men, to just above the castrate range. However, due to their other hormonal effects, suppression of estrogen levels alongside testosterone levels, and AR activation, SAAs have increased side effects and show lower efficacy in the treatment of prostate cancer relative to NSAAs.
List of SAAs
Marketed
Used specifically as antiandrogens (major)
Cyproterone acetate (Androcur): A combined AR antagonist and progestogen/antigonadotropin. Also has weak glucocorticoid activity. Previously used widely in the treatment of prostate cancer, but since largely replaced by NSAAs. Also used for androgen-dependent indications in women and transgender women, precocious puberty in boys, and as a means of chemical castration for sexual deviation in men. Widely used in oral contraceptives as well (with ethinylestradiol under the brand names Diane and Diane-35). Not available in the United States. Uniquely among most SAAs, has a high risk of liver changes and hepatotoxicity. Also has a high incidence of psychiatric side effects such as depression, anxiety, and fatigue.
Spironolactone (Aldactone): An antimineralocorticoid (aldosterone antagonist) with additional/coincidental antiandrogen activity. Specifically acts as an AR antagonist, weak antigonadotropin, and weak steroidogenesis inhibitor. Used for androgen-dependent indications in women and transgender women, particularly in the United States where cyproterone acetate is unavailable. Studied in the treatment of benign prostatic hyperplasia but was found to be ineffective. Contraindicated in prostate cancer due to weak androgenic activity and stimulation of tumor growth. Most commonly used as a diuretic and antihypertensive for cardiovascular disease. Commonly associated with gynecomastia (breast development) and menstrual disturbances.
Used specifically as antiandrogens (minor)
Chlormadinone acetate (Prostal): A combined AR antagonist and progestogen/antigonadotropin. Also has weak glucocorticoid activity. Widely used in the treatment of prostate cancer in Japan, but little used for this purpose elsewhere. Has largely been replaced by NSAAs. Mostly used throughout the world in oral contraceptives (with ethinylestradiol under the brand names Belara and Belarina). Not available in the United States.
Gestonorone caproate (Depostat, Primostat): A pure progestogen/antigonadotropin without any direct AR antagonism or other hormonal activity. Injected intramuscularly. Used in the treatment of benign prostatic hyperplasia in certain countries such as the United Kingdom. Not available in the United States.
Hydroxyprogesterone caproate (Proluton, Proluton Depot): A pure progestogen/antigonadotropin without any direct AR antagonism or other hormonal activity. Injected intramuscularly. Studied in the treatment of benign prostatic hyperplasia and showed some albeit only marginal effectiveness. Associated with hypogonadism and causes impotence in two-thirds of men. Mostly used for gynecological and obstetric indications in women.
Medrogestone (Colprone): A progestogen/antigonadotropin with additional activity as an AR antagonist and steroidogenesis inhibitor. Also has weak glucocorticoid activity. Formerly used in the treatment of benign prostatic hyperplasia in men. Most commonly used in the treatment of gynecological disorders and in menopause. It is an older progestin that has mostly been discontinued and is now rarely used.
Medroxyprogesterone acetate (Depo-Provera): A progestogen/antigonadotropin without any direct AR antagonism. Also has weak androgenic and glucocorticoid activity and acts as a steroidogenesis inhibitor at very high dosages. Injected intramuscularly. Used as a means of chemical castration for sexual deviation in men, particularly in the United States where cyproterone acetate is unavailable. Studied in the treatment of prostate cancer but never widely used. Has also been used to prevent precocious puberty. Most commonly used as a long-lasting injectable contraceptive in women.
Megestrol acetate (Megace): A combined AR partial antagonist and progestogen/antigonadotropin. Also has weak androgenic and glucocorticoid activity. Studied in the treatment of prostate cancer but showed poor effectiveness. Mostly used as an appetite stimulant in patients with cachexia.
Oxendolone (Prostetin, Roxenone): A combined AR antagonist and progestogen/antigonadotropin. Marketed in Japan only for the treatment of benign prostatic hyperplasia. Controversial due to low effectiveness observed in clinical studies.
Used as antiandrogens in veterinary medicine
Delmadinone acetate (Tardak): A combined AR antagonist and progestogen/antigonadotropin. Also has weak glucocorticoid activity. Used in veterinary medicine only. Marketed in Europe and Oceania for the treatment of androgen-dependent conditions such as benign prostatic hyperplasia in dogs.
Osaterone acetate (Ypozane): A combined AR antagonist and progestogen/antigonadotropin. Used in veterinary medicine only. Marketed in Europe specifically for the treatment of benign prostatic hyperplasia in dogs. Has been associated with transiently elevated liver enzymes.
Used exclusively as progestins in women
Dienogest (Visanne, Dinagest): Progestin with some AR antagonist activity. Used as an oral contraceptive (with estradiol valerate as Natazia and Qlaira and with ethinylestradiol as Valette) and in the treatment of endometriosis.
Drospirenone: Progestin with antimineralocorticoid and AR antagonist activity. Used in combination with estrogen in hormonal replacement therapy and oral contraceptives (with ethinylestradiol as Yasmin, Yasminelle, and Yaz and with estradiol as Angeliq). Also used (as an oral contraceptive) in the treatment of acne.
Nomegestrol acetate (Lutenyl): Progestin with AR antagonist activity. Used in the treatment of gynecological disorders and in hormonal replacement therapy and oral contraceptives (with estradiol as Naemis and Zoely).
Miscellaneous
Mifepristone (RU-486; Mifegyne, Mifeprex): An antiprogestogen which is widely used as an abortifacient. Also has antiglucocorticoid and AR antagonist activity. Has been found to produce gynecomastia as a side effect in men at a relatively high rate in clinical studies. Has been studied as a treatment for prostate cancer.
Steroidal androgen synthesis inhibitors like the CYP17A1 inhibitor abiraterone acetate (Zytiga) or the 5α-reductase inhibitors finasteride and dutasteride could also technically be described as "SAAs", but the term is usually reserved to describe AR antagonists (and sometimes progestogenic antigonadotropins).
Not marketed
Under development
Clascoterone (CB-03-01; Breezula, Winlevi): A pure AR antagonist. Topical without any systemic activity. Under development for the treatment of acne and pattern hair loss (androgenic alopecia).
Development discontinued
11α-Hydroxyprogesterone (11α-OHP): Possibly the first antiandrogen to be discovered. Weak antiandrogen used topically. Studied in the 1950s for the treatment of androgen-dependent skin conditions like acne and reportedly showed some effectiveness but was never marketed.
Benorterone (SKF-7690, FC-612): A pure AR antagonist without progestogenic activity, though with some antigonadotropic activity through an undefined mechanism. One of the earliest antiandrogens. Studied in the treatment of acne, seborrhea, and hirsutism in the 1960s but was found to produce a very high rate of gynecomastia in males. Development was discontinued in favor of cyproterone acetate, which showed only a low rate of gynecomastia in males.
BOMT (Ro 7-2340): A pure AR antagonist without other progestogenic activity, though with some antigonadotropic activity through an undefined mechanism. One of the earliest antiandrogens. Studied in the treatment of benign prostatic hyperplasia but was never marketed. Was also of interest for the potential treatment of acne, pattern hair loss (androgenic alopecia), and prostate cancer, but was never studied for such uses.
Cyproterone (SH-80881, SH-881): A pure AR antagonist without progestogenic activity, showing robust progonadotropic activity like NSAAs. One of the earliest antiandrogens. Was studied in the treatment of precocious puberty as well as acne, seborrhea, and hirsutism. Showed surprisingly poor effectiveness in clinical trials and was abandoned in favor of cyproterone acetate.
Delanterone (GBR-21162): An AR antagonist which was described in the literature in 1977. Was under development for the treatment of acne but showed poor effectiveness in preclinical studies and was abandoned.
Galeterone (TOK-001, VN/124-1): A dual AR antagonist and steroidogenesis inhibitor which was under development for the treatment of prostate cancer but showed insufficient effectiveness in clinical trials and was discontinued.
Inocoterone acetate (RU-38882, RU-882): A steroid-like NSAA. It was under development as a topical medication for the treatment of acne but was discontinued due to insufficient effectiveness in clinical trials.
Metogest (SC-14207): An AR antagonist which was patented in 1975 and briefly investigated for the treatment of acne but was never marketed.
Rosterolone (SH-434): A pure AR antagonist without other hormonal activity. Developed as a topical antiandrogen without systemic activity. Showed some effectiveness in the treatment of acne, but was never marketed.
Topterone (WIN-17665): An AR antagonist which was described in the literature in 1977. Developed as a topical antiandrogen. Was under development for the treatment of acne but showed poor effectiveness and was abandoned.
Trimethyltrienolone (R-2956): An extremely potent AR antagonist without other hormonal activity derived from the powerful anabolic–androgenic steroid metribolone (methyltrienolone). Was under investigation for potential clinical use but development was discontinued in favor of NSAAs, which in contrast show a complete lack of intrinsic androgenic activity.
Zanoterone (WIN-49596): A pure AR antagonist without other hormonal activity except some antiprogestogenic activity in animal models. Was under development for the treatment of benign prostatic hyperplasia but showed poor effectiveness and a high rate of breast pain and gynecomastia in clinical trials and was subsequently abandoned.
Many spirolactone antimineralocorticoids that were never marketed like dicirenone, mespirenone, mexrenone, prorenone, SC-5233 (spirolactone), spirorenone, and spiroxasone also show varying degrees of activity as AR antagonists.
See also
Discovery and development of antiandrogens
List of steroidal antiandrogens
References
Further reading
Anti-acne preparations
Antiandrogens
Antigonadotropins
Hair loss medications
Hair removal
Hormonal antineoplastic drugs
Prostate cancer
Sex hormones
Steroids | Steroidal antiandrogen | [
"Biology"
] | 2,975 | [
"Behavior",
"Sexuality",
"Sex hormones"
] |
51,496,340 | https://en.wikipedia.org/wiki/PTS%20Mannose-Fructose-Sorbose%20Family | The PTS Mannose-Fructose-Sorbose (Man) Family (TC# 4.A.6) is a group of multicomponent PTS systems that are involved in sugar uptake in bacteria. This transport process is dependent on several cytoplasmic phosphoryl transfer proteins - Enzyme I (I), HPr, Enzyme IIA (IIA), and Enzyme IIB (IIB) as well as the integral membrane sugar permease complex (IICD). It is not part of the PTS-AG or PTS-GFL superfamilies.
Distinguishing characteristics from other PTS porters
The Man Family is unique in several respects among other PTS porter families:
It is the only PTS family in which members possess a IID protein;
It is the only PTS family in which the IIB constituent is phosphorylated on a histidyl rather than a cysteyl residue;
Its porter members usually exhibit broad specificity for a range of sugars, rather than being specific for just one or a few sugars.
The mannose porter of Escherichia coli, for example, can transport and phosphorylate glucose, mannose, fructose, glucosamine, N-acetylglucosamine, and N-acteylmannosamine.
Structure
The structure of the E. coli IIAMan domain has been shown to exhibit an α/β doubly wound superfold. The IIB domain also exhibits an α/β doubly wound superfold, but it is very dissimilar from that of the IIA domain. Instead, it has the same topology as phosphoglyceromutase (PGM). Since both proteins (IIBMan and PGM) catalyze phosphoryl transfer with a phosphohistidine intermediate, both proteins show a similar distribution of active site residues, and both exhibit similar structures, they are probably homologous.
IICMan of E. coli has been reported to have six transmembrane α-helical segments, while IIDMan was reported to have only one. However, hydropathy plots show multiple peaks of hydropathy, rendering the experimental result, suggesting 1 TMS, questionable. These two proteins together are required for transport, although IICMan is presumed to comprise all or most of the sugar transporting channel.
Transport reaction
The generalized reaction catalyzed by members of the Man Family is:
Sugar (out) + PEP (in) → Sugar-P (in) + pyruvate (in)
References
Membrane proteins
Protein families | PTS Mannose-Fructose-Sorbose Family | [
"Biology"
] | 543 | [
"Protein families",
"Protein classification",
"Membrane proteins"
] |
51,496,520 | https://en.wikipedia.org/wiki/Strongback%20%28girder%29 | A strongback is a beam or girder which acts as a secondary support member to an existing structure. A strongback in a staircase is usually ordinary two-by dimensional lumber attached to the staircase stringers to stiffen the assembly. In shipbuilding, a strongback, known as a waler is oriented lengthwise along a ship to brace across several frames to keep the frames square and plumb. In formwork strongbacks (typically vertical) reinforce typically horizontal walers to provide additional support against hydrostatic pressure during concrete pours.
Some rockets like the Antares, the Falcon 9 and the Falcon Heavy use a strongback to restrain the rocket prior to launch. This structure tilts several degrees away from the rocket to clear the launch, either at the moment of launch or a few minutes before.
References
Building materials
Construction | Strongback (girder) | [
"Physics",
"Engineering"
] | 166 | [
"Building engineering",
"Construction",
"Materials",
"Building materials",
"Architecture stubs",
"Matter",
"Architecture"
] |
51,496,610 | https://en.wikipedia.org/wiki/Reduced%20folate%20carrier%20family | The Reduced Folate Carrier (RFC) Family (TC# 2.A.48) is a group of transport proteins that is part of the major facilitator superfamily. RFCs take up folate, reduced folate, derivatives of reduced folate and the drug, methotrexate.
Structure and Homology
These proteins are usually 500-600 amino acyl residues long and possess 12 putative transmembrane α-helical segments (TMSs). Residues in the first TMS and in the region between TMSs 1 and 2, and in TMS 11 appear to play roles in substrate recognition. The large cytoplasmic loop between TMSs 6 and 7 is required for stability and efficient transport.
Proteins of the RFC family have been characterized only from animals, but homologues can also be found in other eukaryotes such as slime molds and Giardia. They have been sequenced from several mammals and from the worm, Caenorhabditis elegans, as well as the fly, Drosophila melanogaster. Humans have at least two RFC family paralogues, and C. elegans has three. All homologues exhibit a high degree of sequence similarity with each other.
Proposed Mechanisms
The RFC members appear to transport reduced folate by an energy-dependent, pH-dependent, Na+-independent mechanism. Folate:H+ symport, folate:OH−antiport and folate:anion antiport mechanisms have been proposed. Intracellular anions are able to promote folate derivative uptake. A bidirectional anion antiport mechanism for RFC family members is favored. In support of this notion, RFC1 has been shown to catalyze efflux of thiamin pyrophosphate (TPP).
Transport Reactions
The generalized transport reactions catalyzed by the proteins of the RFC family are:
Folate derivative (out) + anion (in) ⇌ folate derivative (in) + anion (out)
Thiamine (out) + H+ (out) ⇌ thiamine (in) + H+ (in)
TPP (in) + H+ (in) ⇌ TPP (out) + H+ (out)
Medical relevance
Several human RFCs have been linked to chronic kidney disease. In particular, RFC1, ThTr-1, and ThTr-2 have been shown to be downregulated in heart, liver and brain, causing malabsorption.
See also
Reduced folate carrier 1
References
Protein families
Membrane proteins
Transmembrane proteins
Transmembrane transporters
Transport proteins
Integral membrane proteins | Reduced folate carrier family | [
"Biology"
] | 554 | [
"Protein families",
"Protein classification",
"Membrane proteins"
] |
51,497,005 | https://en.wikipedia.org/wiki/Equilibrative%20nucleoside%20transporter%20family | Members of the Equilibrative Nucleoside Transporter (ENT) Family (TC# 2.A.57) are transport proteins that are specific to nucleosides and nucleobases, and are part of the major facilitator superfamily. They generally possess at least 6, typically 10, transmembrane segments (TMSs) and are 300-600 amino acyl residues in length.
Function
ENTs, including those in parasitic protozoa, function in nucleoside and nucleobase uptake for salvage pathways of nucleotide synthesis and, in humans, are also responsible for the cellular uptake of nucleoside analogues used in the treatment of cancers and viral diseases. By regulating the concentration of adenosine available to cell surface receptors, mammalian ENTs additionally influence physiological processes ranging from cardiovascular activity to neurotransmission.
Human ENTs
In humans ENT are also known as SLC29, a group of plasmalemmal transport proteins which transport nucleoside substrates like adenosine into cells. There are four known human ENTs, designated ENT1, ENT2, ENT3, and ENT4. They are blocked by adenosine reuptake inhibitors like dipyridamole and dilazep, drugs used clinically for their vasodilatory properties.
The best-characterized members of the human Ent family, hENT1 and hENT2, possess similar broad permeant selectivities for purine and pyrimidine nucleosides, but hENT2 also efficiently transports nucleobases. hENT3 has a similar broad permeant selectivity for nucleosides and nucleobases and appears to function in intracellular membranes, including lysosomes. Gemcitabine, an anti-cancer drug, is transported by hENT1 and hENT3. hENT4 is uniquely selective for adenosine, and also transports a variety of organic cations.
Transport reaction
The generalized transport reaction catalyzed by well characterized ENT family members is:
Nucleoside (out) → Nucleoside (in)
See also
Concentrative nucleoside transporter
Nucleoside transporter
Further reading
References
Protein families
Membrane proteins
Transmembrane proteins
Transmembrane transporters
Transport proteins
Integral membrane proteins | Equilibrative nucleoside transporter family | [
"Biology"
] | 493 | [
"Protein families",
"Protein classification",
"Membrane proteins"
] |
51,497,071 | https://en.wikipedia.org/wiki/Hot%20Rodders%20of%20Tomorrow | Hot Rodders of Tomorrow is an American national competition where high school students tear-down and rebuild an engine in the shortest time possible. The competition is run by a non-profit organization.
The organization has awarded over US$15.5 million in scholarships, including $4.55 million in 2015.
References
External links
Mechanical engineering competitions | Hot Rodders of Tomorrow | [
"Engineering"
] | 69 | [
"Mechanical engineering competitions",
"Mechanical engineering"
] |
51,497,943 | https://en.wikipedia.org/wiki/Organo%20anion%20transporter%20family | Members of the Organic Anion Transporter (OAT) Family (organic-anion-transporting polypeptides, OATP) are membrane transport proteins or 'transporters' that mediate the transport of mainly organic anions across the cell membrane. Therefore, OATPs are present in the lipid bilayer of the cell membrane, acting as the cell's gatekeepers. OATPs belong to the Solute Carrier Family (SLC) and the major facilitator superfamily.
The generalized transport reactions catalyzed by members of the OAT family are:
Anion (in) → Anion (out)
Anion1 (in) + Anion2 (out) → Anion1 (out) + Anion2 (in)
Function
Proteins of the OAT family catalyze the Na+-independent facilitated transport of fairly large amphipathic organic anions (and less frequently neutral or cationic drugs), such as bromosulfobromophthalein, prostaglandins, conjugated and unconjugated bile acids (taurocholate and cholate), steroid conjugates, thyroid hormones, anionic oligopeptides, drugs, toxins and other xenobiotics. One family member, OATP2B1, has been shown to use cytoplasmic glutamate as the exchanging anion. Among the well characterized substrates are numerous drugs including statins, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, antibiotics, antihistaminics, antihypertensives and anticancer drugs. Other substrates include luciferin, thyroid hormones and quinolones.
Organic anion transporting polypeptides carry bile acids as well as bilirubin and numerous hormones such as thyroid and steroid hormones across the basolateral membrane (facing sinusoids) in hepatocytes, for excretion in bile. As well as expression in the liver, OATPs are expressed in many other tissues on basolateral and apical membranes, transporting anions, as well as neutral and even cationic compounds. They also transport an extremely diverse range of drug compounds, ranging from anti-cancer, antibiotic, lipid lowering to anti-diabetic drugs, as well as toxins and poisons.
Various anti-cancer drugs like pazopanib, vandetanib, nilotinib, canertinib and erlotinib are known to be transported via OATPs (OATP-1B1 and OATP-1B3). Some of these have also been reported as inhibitors of certain OATPs: pazopanib and nilotinib against OATP-1B1 and vandetanib against OATP-1B3.
They also transport the dye bromosulphopthalein, availing it as a liver-testing substance.
Homology
The various paralogues in a mammal have differing but overlapping substrate specificities and tissue distributions as summarized by Hagenbuch and Meier. These authors also provide a phylogenetic tree of the mammalian members of the family, showing that they fall into five recognizable subfamilies, four of which exhibit deep branching sub-subfamilies. However, all sequences within a subfamily are >60% identical while those between subfamilies are >40% identical. As also shown by Hagenbuch and Meier, all but one (OatP4a1) of the mammalian homologues cluster together, separately from all other animal (insect and worm) homologues.
OAT family homologues have been found in other animals but not outside of the animal kingdom. These transporters have been characterized in mammals, but homologues are present in Drosophila melanogaster, Anopheles gambiae, and Caenorhabditis elegans. The mammalian OAT family proteins exhibit a high degree of tissue specificity.
Human proteins
The table below shows the 11 known human OATPs. Note: Human OATPs are designated with capital letters, animal Oatps are designated with lower class letters. The 'SLCO' stands for their gene name; 'solute carrier organic anion.' Previous nomenclature using letters and numbers (e.g. OATP-A, OATP-8 is no longer used.
The most well characterised human OATPs are OATP1A2, OATP1B1, OATP1B3 and OATP2B1. Very little is known about the function and characteristics of OATP5A1 and OATP6A1.
Pharmacology
The OATPs play a role in the transport of some classes of drugs across the cell membrane, particularly in the liver and kidney. In the liver, OATPs are expressed on the basolateral membrane of hepatocytes, transporting compounds into the hepatocyte for biotransformation. A number of drug-drug interactions have been associated with the OATPs, affecting the pharmacokinetics and pharmacodynamics of drugs. This is most commonly where one drug inhibits the transport of another drug into the hepatocyte, so that it is retained longer in the body (i.e. increased plasma half-life). The OATPs most associated with these interactions are OATP1B1, OATP1B3 and OATP2B1, which are all present on the hepatocyte basolateral (sinusoidal) membrane. OATP1B1 and OATP1B3 are known to play an important role in hepatic drug disposition. These OATPs contribute towards first step of hepatic accumulation and can influence the disposition of drug via hepatic route. The most clinically relevant interactions have been associated with the lipid lowering drugs statins, which led to the removal of cerivastatin from the market in 2002. Single nucleotide polymorphisms (SNPs) are also associated with the OATPs; particularly OATP1B1.
Many modulators of OATP function have been identified based on in vitro research in OATP-transfected cell lines. Both OATP activation and inhibition has been observed and an in silico model for structure-based identification of OATP modulation was developed.
Since tyrosine kinase inhibitors (TKIs) are metabolized in the liver, interaction of TKIs with OATP1B1 and OATP1B3 can be considered as important molecular targets for transporter mediated drug-drug interactions.
Along with the organic cation transporters and the ATP-binding cassette transporters, the OATPs play an important role in the absorption, distribution, metabolism and excretion (ADME) of many drugs.
Evolution
OATPs are present in many animals, including fruit flies, zebrafish, dogs, cows, rats, mice, monkeys and horses. OATPs are not present in bacteria, indicating their evolution from the animal kingdom. However homologs do not correlate well with the human OATPs and therefore it is likely that isoforms arose by gene duplication. OATPs have however been found in insects, suggesting that their evolution was early in the formation of the animal kingdom.
References
Solute carrier family
Protein families
Membrane proteins
Transmembrane proteins
Transmembrane transporters
Transport proteins
Integral membrane proteins
Thyroid hormone transporters | Organo anion transporter family | [
"Biology"
] | 1,566 | [
"Protein families",
"Protein classification",
"Membrane proteins"
] |
51,498,943 | https://en.wikipedia.org/wiki/Ethanesulfonic%20acid | Ethanesulfonic acid (esylic acid) is a sulfonic acid with the chemical formula CH3CH2SO3H. The conjugate base is known as ethanesulfonate or, when used in pharmaceutical formulations, as esilate. It is a colorless liquid.
References
External links
Ye YK, Stringham RW (2006), The effect of acidic and basic additives on the enantioseparation of basic drugs using polysaccharide-based chiral stationary phases. Chirality 18, 519–530. (PubMed:16676332)
National Center for Biotechnology Information (2005), Ethanesulfonic acid, PubChem Compound Database; CID=11668, (accessed December 23, 2016)
https://www.scbt.com/scbt/product/ethanesulfonic-acid-594-45-6
http://www.chemicalbook.com/productmsdsdetailcb5173859_en.htm
Sulfonic acids | Ethanesulfonic acid | [
"Chemistry"
] | 223 | [
"Functional groups",
"Organic compounds",
"Sulfonic acids",
"Organic compound stubs",
"Organic chemistry stubs"
] |
51,499,423 | https://en.wikipedia.org/wiki/Grunt%20%28software%29 | Grunt is a JavaScript task runner, a tool used to automatically perform frequent tasks such as minification, compilation, unit testing, and linting. It uses a command-line interface to run custom tasks defined in a file (known as a Gruntfile). Grunt was created by Ben Alman and is written in Node.js. It is distributed via npm. As of October 2022, there were more than 6,000 plugins available in the Grunt ecosystem.
Companies and projects that use Grunt include Adobe Systems, jQuery, Twitter, Mozilla, Bootstrap, Cloudant, Opera, WordPress, Walmart, and Microsoft.
Overview
Grunt was originally created by Ben Alman in 2012 as an efficient alternative to simplify writing and maintaining a suite of JavaScript build process tasks in one huge file. It was designed as a task-based command line build tool for JavaScript projects.
Grunt is primarily used to automate tasks that need to be performed routinely. There are thousands of plugins that can be installed and used directly to accomplish some commonly used tasks. One of Grunt's most desirable features is that it is highly customizable—i.e., it allows developers to add, extend, and modify custom tasks to fit their personal needs; each task has a set of configuration options that the user can set. Moreover, Grunt offers the ability to define custom tasks, which can combine multiple existing tasks into a single task or add entirely new functionality.
Basic concepts
Command-line interface
Grunt's command-line interface (CLI) can be installed globally through npm. Executing the grunt command will load and run the version of Grunt locally installed in the current directory. Hence, we can maintain different versions of Grunt in different folders and execute each one as we wish.
Files
To use Grunt in a project, two specific files need to be created in the root directory, namely package.json and a Gruntfile.
package.json - contains the metadata for the project including name, version, description, authors, licenses and its dependencies (Grunt plugins required by the project). All the dependencies are listed either in the dependencies or the devDependencies section.
Gruntfile - a valid JavaScript or CoffeeScript file named "Gruntfile.js" or "Gruntfile.coffee" that contains code to configure tasks, load existing plugins and/or create custom tasks.
Tasks
Tasks are the modules that perform a specified job. They are defined in the Gruntfile.
Developers can load predefined tasks from existing Grunt plugins and/or write custom code to define their own tasks depending on their requirements. Once defined, these tasks can be run from the command line by simply executing grunt <taskname>. If the <taskname> defined in the Gruntfile is 'default' then simply executing grunt will suffice.
Example
The following is an example of a Gruntfile written in JavaScript that shows how to load plugins, create custom tasks and configure them:
module.exports = function(grunt) {
// Task configuration
grunt.initConfig({
taskName1: 'Task1 Configuration',
taskName2: 'Task2 Configuration'
});
// Loads plugins
grunt.loadNpmTasks('pluginName1');
grunt.loadNpmTasks('pluginName2');
// Custom tasks
grunt.registerTask('customTaskName1', 'Custom task description', function(taskParameter) {
// Custom statements
});
// Combining multiple tasks to a single task
grunt.registerTask('customTaskName2', ['taskName1', 'customTaskName1']);
// Default task - runs if task name is not specified
grunt.registerTask('default', ['customTaskName2']);
};
In the above example, executing the grunt command will run <customtaskName2> which has been defined above as a combination of both <taskName1> and <customTaskName1>.
Plugins
Plugins are reusable code that defines a set of tasks. Each plugin internally contains a tasks directory with JavaScript files that have the same syntax as a Gruntfile. Most of the Grunt plugins are published with the keyword gruntplugin in npm and prefixed with grunt. This helps Grunt in showing all the plugins in Grunt's plugin listing. The plugins officially supported by Grunt are prefixed with grunt-contrib and are also marked with a star symbol in the plugins listing. Some popular plugins include grunt-contrib-watch, grunt-contrib-clean, grunt-contrib-uglify.
Developers can even create their own Grunt plugins by using the grunt-init plugin and publish them to npm using the npm publish command.
Advantages
The following are some of the advantages of using Grunt:
All task runners have the following properties: consistency, effectiveness, efficiency, repeatability, etc.
Access to many predefined plugins that can be used to work with JavaScript tasks and on static content.
Allows users to customize tasks using predefined plugins.
Prefers the configuration approach to coding.
Allows users to add their own plugins and publish them to npm.
Comparison
Ant
Ant or Apache Ant is a Java-based build tool. Ant has a little over a hundred built-in tasks that are better suited to projects with a Java build structure. Writing custom code in Ant requires users to write a JAR file and reference it from XML. This would add unnecessary complexities to projects that do not require Java themselves. Ant build configurations are listed in XML rather than in JSON format.
Rake
Rake allows developers to define tasks in Ruby. Rake doesn't have the concept of plugins or predefined tasks which means all the required actions must be written and then executed. This makes the developments costly when compared to Grunt which has a large set of reusable plugins.
Gulp
Gulp.js is a JavaScript based task runner tool similar to Grunt since both follow a modular-based architecture and are based on npm. Gulp tasks are defined by code rather than configuration. Gulp is faster than Grunt. Grunt uses temporary files to transfer output from one task to another whereas in Gulp files are piped between the tasks.
See also
Node.js
Build automation
List of build automation software
Apache Maven
Yeoman (computing)
Modernizr
JavaScript framework
JavaScript library
References
Further reading
External links
Automation software
JavaScript programming tools | Grunt (software) | [
"Engineering"
] | 1,389 | [
"Automation software",
"Automation"
] |
67,211,745 | https://en.wikipedia.org/wiki/Electronic%20Design%20%28magazine%29 | Electronic Design magazine, founded in 1952, is an electronics and electrical engineering trade magazine and website.
History
Hayden Publishing Company began publishing the bi-weekly magazine Electronic Design in December 1952, and was later published by InformaUSA, Inc.
In 1986, Verenigde Nederlandse Uitgeverijen, purchased Hayden Publishing Inc.
In June 1988, Verenigde Nederlandse Uitgeverijen, purchased Electronic Design from McGraw-Hill.
In July 1989, Penton Media, purchased Electronic Design, then in Hasbrouck, N.J., from Verenigde Nederlandse Uitgeverijen.
In July 2007, Penton Media's OEM electronics publication, EE Product News, merged with Penton Media's "Electronic Design" magazine. EE Product News was founded in 1941, as a monthly publication.
In September 2016, Informa, purchased Penton Media, including Electronic Design.
In November 2019, Endeavor Business Media purchased Electronic Design from Informa.
Content
Sections include Technology Reports (products), Engineering Essentials (new standards), Engineering Features (events), and Embedded in Electronic Design (embedded hardware and software). Design Solutions are contributed by field engineers and Ideas For Design are submitted by readers. Electronic Design also covers components. Techview presents news and products in the categories of Analog & Power, Digital, Electronic design automation, Communications, Test, and Wireless. The magazine covers emerging technologies and large-scale trends.
Six "big" issues are published per year. The Technology Forecast issue is published in January. In June, the Megatrends issue describes industry trends. The "Best" issue reviews the year's "best" designs, events and products. "Your Issue" covers topics from the annual reader survey results. "One Powerful Issue" covers Power and "Wireless Everywhere" covers Wireless.
Editorial staff include: William Wong, Senior Content Director; James Morra, Senior Editor; Andy Turudic, Technology Editor; Cabe Atwell, Technology Editor; Alix Paultre, Editor-at-Large; and David Maliniak, Senior Editor.
Notable contributor
Bob Pease was an electronics engineer and author employed by National Semiconductor Corporation who wrote a monthly column, Pease Porridge, about analog electronics, and answered letters.
Distribution
The publication is free, in print and PDF, for qualified engineers and North American industry managers. It is also available online.
See also
EE Times
EDN
Electronics (magazine)
Electronic News
References
External links
Electronic Design
Endeavor Business Media
Engineering magazines
Magazines established in 1952
Professional and trade magazines
Magazines published in New York City
Science and technology magazines published in the United States
Electrical and electronic engineering magazines | Electronic Design (magazine) | [
"Engineering"
] | 547 | [
"Electrical engineering",
"Electronic engineering",
"Electrical and electronic engineering magazines"
] |
67,212,123 | https://en.wikipedia.org/wiki/International%20Network%20of%20Women%20Engineers%20and%20Scientists | International Network of Women Engineers and Scientists (INWES) is a current network for women professionals, which was founded in 2002 with the intention to support women and girls in engineering and science across the world. The current (2020-2023) President is Jung Sun Kim, from Dongseo University, South Korea.
According to their mission statement, the network seeks to encourage the education and retention of professional women in these fields through international collaboration. The founding of the network received support from UNESCO. Founding members include Canadian engineers Claire Deschênes, Monique Frize and Gail Mattson, current Immediate Past President of INWES and past president of SWE, Society of Women Engineers, USA. The network currently has over 60 countries involved, including the Association of Korean Women Scientists and Engineers, Women's Engineering Society (UK), the German Association of Women Engineers (DIB), the Society of Taiwan Women in Science and Technology (TWiST) and African Women in Science and Engineering (AWSE).
Management of the International Conference of Women Engineers and Scientists
The network took over the management of the International Conference of Women Engineers and Scientists (ICWES), which first took place in 1964 in New York and has met every 3–4 years since then. ICWES serves as a meeting point for women practitioners in science and engineering from across the world. Since INWES took over the management of the conference, it has taken place in Ottawa, Canada (2002); Seoul, Korea (2005); Lille, France (2008); Adelaide, Australia (2011); Los Angeles, USA (2014); and New Delhi, India (2017). ICWES 18 will take place in Coventry, UK, in 2021.
INWES archives
The archives of INWES are held in the University of Ottawa Archives and Special Collections.
Education and Research Institute
The Education and Research Institute (INWES-ERI) is an initiative of INWES.
References
Women in science and technology | International Network of Women Engineers and Scientists | [
"Technology"
] | 395 | [
"Women in science and technology"
] |
67,212,287 | https://en.wikipedia.org/wiki/Ascodichaena%20rugosa | Ascodichaena rugosa is a species of fungus in the family Ascodichaenaceae. It was first scientifically described as a new species by Carl Linnaeus in 1753 as Lichen rugosum. Heinz Butin transferred it to the newly circumscribed genus Ascodichaena in 1977, in which it is the type species.
References
Leotiomycetes
Fungi of Europe
Fungi of North America
Fungi described in 1753
Taxa named by Carl Linnaeus
Fungus species | Ascodichaena rugosa | [
"Biology"
] | 102 | [
"Fungi",
"Fungus species"
] |
67,212,817 | https://en.wikipedia.org/wiki/Heresthetic | Heresthetic is an approach to understanding how political actors manipulate the decision-making process so they can win. Heresthetic is a positive political theory, including aspects of game theory, public choice theory, rational choice theory, and social choice theory to political science. Political scientist William H. Riker is considered the creator and one of the most prominent supports of theory.
Description
Riker argues that herestheticians win because they compel or persuade others to join them in voting or political coalitions. Heresthetic focuses both on the use of rhetoric and political strategy. Riker argues that there are three vital components to heresthetic.
Agenda control: political agents may structure debate in ways that highlight favorable or eliminate undesirable policy alternatives. Depending upon the order that policy options are discussed, debate can produce different outcomes, including outcomes that are not preferred by the heresthetician. The order of choice matters. Riker's concept of agenda control differs from conventional accounts of agenda-setting involving policy-makers, which focus on how policy-makers’ agendas are influenced by exogenous factors, such as the media and public opinion. Riker's focus is on how policy-makers affect the ordering of items on the political agenda, and how that ordering can be manipulated.
Strategic voting: in deliberative settings herestheticians can take advantage of voting procedures to influence outcomes. For example, agents may vote against their own interest in the short-term to secure a better long-term position. Another element of strategic voting is vote trading. Policy-makers may informally trade votes with others in exchange for future votes or benefits. Strategic voting is common in legislative settings because of open rules and sequential voting procedures.
Dimension manipulation: herestheticians can manipulate the dimensionality of political decision-making by introducing new dimensions or modifying existing framing. Dimension manipulation can either expand a decision-making space by reconfiguring acceptable topics of debate and policy alternatives, or shrink dimensions by eliminating certain topics or alternatives. The manipulation of dimensions is important because once an agent manipulates framing, it cannot be removed from debate.
These components allow herestheticians to manipulate political outcomes by structuring debate, rhetorically or structurally, to be more advantageous to their preferred position.
Example
The British Parliament is scheduling upcoming referendum votes to determine Scottish independence from the United Kingdom and if the UK should remain a member of the European Union. A member of parliament who has influence on how the votes will be structured, has a preference that Scotland will remain in union with the UK and that the UK will leave the EU. Scottish independence and the UK remaining a member of the EU is an undesirable outcome for the MP. While polling indicates that a majority of Scottish voters do not support independence, voters are more likely to support independence if the UK leaves the EU. In order to receive his preferred outcome, the MP seeks for the referendum votes to be held in a sequence in which Scottish independence is determined first, and then UK withdrawal from the EU. This voting sequence demonstrates how herestheticians can manipulate the decision-making process so they can win.
See also
Agenda-setting theory
Choice modelling
Opportunism
Political economy
Tactical voting
Voting systems
References
Game theory
Public choice theory
Political science
Political science theories
Political theories
Public economics
Sociological theories | Heresthetic | [
"Mathematics"
] | 674 | [
"Game theory"
] |
67,213,205 | https://en.wikipedia.org/wiki/Melampsora%20pulcherrima | Melampsora pulcherrima is a Mediterranean plant pathogen. It is a rust that infects Mercurialis annua, causing galls, pycnia, and aecia over leaves and stem in winter, seen as a golden yellow swelling over several centimeters, as well as Populus alba, causing uredia and telia on leaves from spring until autumn.
References
External links
in
Penetration and earlycolonization in basidiospore-derived infection of Melampsora pulcherrima (Bub.)Maire on Mercurialis annua L.
Pucciniales
Fungi described in 1914
Fungi of Europe
Fungal plant pathogens and diseases
Taxa named by René Maire
Fungus species | Melampsora pulcherrima | [
"Biology"
] | 149 | [
"Fungi",
"Fungus species"
] |
67,213,766 | https://en.wikipedia.org/wiki/Qatar-3 | Qatar-3 is a 12th magnitude star located in the northern constellation Andromeda. It is host to a transiting planet. With a radial velocity of 10.99 km/s, it is drifting away from the Solar System, and is currently located 2,400 light years away based on its annual parallax.
Properties
This star is a hot yellow dwarf with 14.5% more mass than the Sun, and 27.2% larger. It has a luminosity of almost two times that of the Sun, and has effective temperature of 5,991 K, which gives it a yellow hue. Qatar-3 is also a metal poor star that has a similar metallicity to the Sun, and has a rapid rotation rate of 10.4 km/s. This means it takes Qatar-3 6.31 days to complete a full rotation, while the Sun takes almost a month to rotate.
Planetary system
In 2016, the Qatar Exoplanet Survey discovered a planet around Qatar-3, Qatar-4, and Qatar-5, which was led by an international team in Qatar. Qatar-3b is a massive planet, with 4.31 times the mass of Jupiter, and has a similar radius to the latter. With a density of , this is one of the densest planets discovered. With an effective temperature of , it is a scorching planet.
Qatar-3b
Qatar-3b is a hot Jupiter. It orbits its star every 2.5 days. It was discovered in 2016 by the Qatar Exoplanet Survey (QES). This planet was discovered by QES along with Qatar-4b and Qatar-5b. The light curves of the planet's respective host stars have been observed as well during the survey, along with their stellar properties.
Orbit
This planet is another typical hot Jupiter. It orbits very close to its star with a period of 2 days, 12 hours, 11 minutes, and 24 seconds. This corresponds with an orbital distance of about 0.04 AU, which is 10 times closer to its star than Mercury is to the Sun. With an eccentricity of 0, this suggests that Qatar-3b is on a perfectly circular orbit.
Physical properties
Qatar-3b is a massive planet, with 4.31 times the mass of Jupiter, but a similar radius. With a density of 4.0 g cm−3, this is one of the densest planets discovered. With an effective temperature of 1,681 K, it is a scorched planet.
References
G-type main-sequence stars
Andromeda (constellation) | Qatar-3 | [
"Astronomy"
] | 531 | [
"Andromeda (constellation)",
"Constellations"
] |
67,215,509 | https://en.wikipedia.org/wiki/USA-235 | USA-235, also known as Advanced Extremely High Frequency 2 or AEHF-2, is a military communications satellite operated by the United States Air Force. It is the second of six satellite to be launched as part of the Advanced Extremely High Frequency program, which replaced the earlier Milstar system.
Satellite description
The USA-235 satellite was constructed by Lockheed Martin Space, and is based on the A2100 satellite bus. The satellite has a mass of and a design life of 14 years. It will be used to provide super high frequency (SHF) and extremely high frequency (EHF) communications for the United States Armed Forces, as well as those of the United Kingdom, the Netherlands, and Canada.
Launch
USA-235 was launched by United Launch Alliance, aboard an Atlas V 531 flying from Space Launch Complex 41 (SLC-41) at the Cape Canaveral Air Force Station (CCAFS). The launch occurred at 18:24 UTC on 4 May 2012, first placing the satellite in a parking orbit of 185 kilometers by 905 kilometers. A second burn placed the satellite into a geostationary transfer orbit (GTO) with a perigee of , an apogee of , and 20.6° inclination. The satellite was successfully deployed in this orbit 51 minutes after launch.
See also
2012 in spaceflight
References
Military communications
Communications satellites of the United States | USA-235 | [
"Engineering"
] | 282 | [
"Military communications",
"Telecommunications engineering"
] |
67,217,185 | https://en.wikipedia.org/wiki/Deterenol | Deterenol (also known as Isopropylnorsynephrine and Isopropyloctopamine; trade name Betaphrine) is a stimulant drug which acts as a beta agonist. It has been found as an ingredient of dietary supplement products, but is banned in most countries due to risk of cardiac arrest.
See also
Halostachine
Isoprenaline
Isopropylamphetamine
Methylhexanamine
Octopamine
Phenpromethamine
Synephrine
Pre-workout
References
Phenylethanolamines | Deterenol | [
"Chemistry"
] | 118 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
67,218,332 | https://en.wikipedia.org/wiki/Flying%20Laptop | The German Flying Laptop satellite, launched on 14 July 2017 on a Soyuz-2.1a launch vehicle from Baikonur Cosmodrome in Kazakhstan, hosts the OSIRISv1 laser communications experiment. The satellite has a total mass of 110 kg. It operates at a Sun-synchronous orbit with an inclination of 97.6 degrees.
The satellite is part of the Stuttgart Small Satellite Program, a program led by the German Space Agency.
Optical communications tests have been carried out with ground stations in Japan, Europe, and Canada, with a data rate of up to 200 Mbit/s, from orbit to ground only.
The two fixed lasers of OSIRISv1 are aimed at ground stations by 'body pointing', attitude control of the entire satellite, using four reaction wheels. The reaction wheels can be desaturated using three internal magnetorquers.
Flying Laptop carries a de-orbit mechanism called DOM2500 developed by Tohoku University and manufactured by Nakashimada Engineering Works, Ltd., which upon activation will unfurl a sail to increase atmospheric drag. The device will be used at the end of the satellite mission.
Further reading
OSIRISv1 on Flying Laptop: Measurement Results and Outlook Fuchs 2019
See also
Laser communication in space
References
Satellites of Germany
Spacecraft launched by Soyuz-2 rockets | Flying Laptop | [
"Astronomy"
] | 272 | [
"Astronomy stubs",
"Spacecraft stubs"
] |
67,218,628 | https://en.wikipedia.org/wiki/NGC%207457 | NGC 7457 is an unbarred lenticular galaxy in the constellation Pegasus. NGC 7457 is its New General Catalogue designation. It was discovered by the astronomer William Herschel on 12 September 1784.
NGC 7457 is estimated to be about 43 million light-years (13.2 megaparsecs) away from the Sun. There are about 201 globular clusters in the galaxy. The core of NGC 7457 is surprisingly bright and compact, with many stars.
References
External links
Pegasus (constellation)
7457
Unbarred lenticular galaxies | NGC 7457 | [
"Astronomy"
] | 112 | [
"Pegasus (constellation)",
"Constellations"
] |
67,218,870 | https://en.wikipedia.org/wiki/Commonwealth%20Engineers%20Council | The Commonwealth Engineers' Council (CEC) is a network of professional engineering institutions of the Commonwealth, established to foster cooperation and exchange of information, support the development of indigenous engineering institutions, and foster the education, training and professional development of engineers. The CEC is an affiliated organisation of The Commonwealth.
History
In the autumn of 1945 the Secretary of The Institution of Civil Engineers (UK) suggested to his President and to The Institution of Mechanical Engineers and to the Institution of Electrical Engineers (now the Institution of Engineering and Technology) that a conference of representatives of Commonwealth Engineering Institutions should be held in London in 1946 to increase collaboration and co-operation between them. In consequence a meeting was held in London in September 1946 and was attended by representatives of institutions in Australia, Canada, India, New Zealand, South Africa and the UK.
Many common problems and matters of common interest were discussed. Moreover it was agreed to establish CEC (it was then called the Commonwealth Engineering Conference) and to meet on a regular basis. Subsequent meetings have been held in
Johannesburg, South Africa 1950
London, UK 1954
Sydney, Melbourne and Canberra, Australia (including New Zealand) 1958
Montreal, Canada 1962
London, UK 1966
Delhi, India 1969
London, UK 1973
Accra, Ghana 1975
London, UK 1977
Hong Kong 1979
Trinidad 1981
Harare, Zimbabwe 1983
Colombo, Sri Lanka 1985
Canada 1987
The pattern of meetings changed from a four year interval to a two year interval when the Commonwealth Foundation which had been founded in 1966 recognized CEC as a Commonwealth Professional Association to which it could grant funds so that representatives could attend meetings.
CEC today
The Institution of Civil Engineers (ICE) serves as the Secretariat for the Commonwealth Engineers’ Council. ICE’s ties to CEC have been longstanding; the immediate Past President of CEC is ICE Past-president Professor Paul Jowitt. The current President of CEC is Dawn Bonfield.
CEC is an International member of the World Federation of Engineering Organisations (WFEO).
The Council’s main aims and objectives are the following:
Foster co-operation and exchange of information among members;
Support the development of indigenous engineering institutions in all member countries, associated states and colonies of the Commonwealth;
Foster the education, training and professional development of engineers;
Encourage and facilitate the transfer of technology between countries;
Promote meetings on engineering and related subjects;
Undertake specific projects and support local programmes;
Support the contribution of engineering to sustainable development and fulfilment of the UN SDGs;
Present the views of the engineering profession to the central Commonwealth bodies such as the Commonwealth Secretariat and through them to Commonwealth Heads of Government.
The CEC reaffiliated to The Commonwealth organisation in 2020 and formed an Executive Board.
References
Engineering organizations
1946 establishments in the United Kingdom | Commonwealth Engineers Council | [
"Engineering"
] | 555 | [
"nan"
] |
67,219,182 | https://en.wikipedia.org/wiki/Contrastive%20Language-Image%20Pre-training | Contrastive Language-Image Pre-training (CLIP) is a technique for training a pair of neural network models, one for image understanding and one for text understanding, using a contrastive objective.
This method has enabled broad applications across multiple domains, including cross-modal retrieval, text-to-image generation, aesthetic ranking, and image captioning.
Publication history
It was first announced on OpenAI's official blog on January 5, 2021, with a report served directly through OpenAI's CDN, and a GitHub repository. The paper was delivered on arXiv on 26 February 2021.
The report (with some details removed, and its appendix cut out to a "Supplementary PDF") was published in Proceedings of the 38th International Conference on Machine Learning, PMLR, which had a submission deadline of February 2021.
Concurrent to CLIP was ALIGN, published at the same conference. It was done by researchers at Google, with essentially the same algorithm.
Algorithm
The CLIP method trains a pair of models contrastively. One model takes in a piece of text as input and outputs a single vector representing its semantic content. The other model takes in an image and similarly outputs a single vector representing its visual content. The models are trained so that the vectors corresponding to semantically similar text-image pairs are close together in the shared vector space, while those corresponding to dissimilar pairs are far apart.
To train a pair of CLIP models, one would start by preparing a large dataset of image-caption pairs. During training, the models are presented with batches of image-caption pairs. Let the outputs from the text and image models be respectively . Two vectors are considered "similar" if their dot product is large.
The loss incurred on this batch is the multi-class N-pair loss, which is a symmetric cross-entropy loss over similarity scores:In essence, this loss function encourages the dot product between matching image and text vectors () to be high, while discouraging high dot products between non-matching pairs. The parameter is the temperature, which is parameterized in the original CLIP model as where is a learned parameter.
Other loss functions are possible. For example, Sigmoid CLIP (SigLIP) proposes the following loss function:where is the negative log sigmoid loss, and the Dirac delta symbol is 1 if else 0.
CLIP models
While the original model was developed by OpenAI, subsequent models have been trained by other organizations as well.
Image model
The image encoding models used in CLIP are typically vision transformers (ViT). The naming convention for these models often reflects the specific ViT architecture used. For instance, "ViT-L/14" means a "vision transformer large" (compared to other models in the same series) with a patch size of 14, meaning that the image is divided into 14-by-14 pixel patches before being processed by the transformer. The size indicator ranges from B, L, H, G (base, large, huge, giant), in that order.
Other than ViT, the image model is typically a convolutional neural network, such as ResNet (in the original series by OpenAI), or ConvNeXt (in the OpenCLIP model series by LAION).
Since the output vectors of the image model and the text model must have exactly the same length, both the image model and the text model have fixed-length vector outputs, which in the original report is called "embedding dimension".
For example, in the original OpenAI model, the ResNet models have embedding dimensions ranging from 512 to 1024, and for the ViTs, from 512 to 768.
Its implementation of ViT was the same as the original one, with one modification: after position embeddings are added to the initial patch embeddings, there is a LayerNorm.
Its implementation of ResNet was the same as the original one, with 3 modifications:
In the start of the CNN (the "stem"), they used three stacked 3x3 convolutions instead of a single 7x7 convolution, as suggested by.
There is an average pooling of stride 2 at the start of each downsampling convolutional layer (they called it rect-2 blur pooling according to the terminology of ). This has the effect of blurring images before downsampling, for antialiasing.
The final convolutional layer is followed by a multiheaded attention pooling.
ALIGN used EfficientNet of various sizes, a kind of convolutional neural network.
Text model
The text encoding models used in CLIP are typically Transformers.
In the original OpenAI report, they reported using a Transformer (63M-parameter, 12-layer, 512-wide, 8 attention heads) with lower-cased byte pair encoding (BPE) with 49152 vocabulary size. Context length was capped at 76 for efficiency. Like GPT, it was decoder-only, with only causally-masked self-attention. Its architecture is the same as GPT-2.
Like BERT, the text sequence is bracketed by two special tokens [SOS] and [EOS] ("start of sequence" and "end of sequence"). Take the activations of the highest layer of the transformer on the [EOS], apply LayerNorm, then a final linear map. This is the text encoding of the input sequence. The final linear map has output dimension equal to the embedding dimension of whatever image encoder it is paired with. These models all had context length 77 and vocabulary size 49408.
ALIGN used BERT of various sizes.
Dataset
WebImageText
The CLIP models released by OpenAI were trained on a dataset called "WebImageText" (WIT) containing 400 million pairs of images and their corresponding captions scraped from the internet. The total number of words in this dataset is similar in scale to the WebText dataset used for training GPT-2, which contains about 40 gigabytes of text data.
The dataset contains 500,000 text-queries, with up to 20,000 (image, text) pairs per query. The text-queries were generated by starting with all words occurring at least 100 times in English Wikipedia, then extended by bigrams with high mutual information, names of all Wikipedia articles above a certain search volume, and WordNet synsets.
The dataset is private and has not been released to the public, and there is no further information on it.
Data preprocessing
For the CLIP image models, the input images are preprocessed by first dividing each of the R, G, B values of an image by the maximum possible value, so that these values fall between 0 and 1, then subtracting by [0.48145466, 0.4578275, 0.40821073], and dividing by [0.26862954, 0.26130258, 0.27577711].
The rationale was that these are the mean and standard deviations of the images in the WebImageText dataset, so this preprocessing step roughly whitens the image tensor. These numbers slightly differ from the standard preprocessing for ImageNet, which uses [0.485, 0.456, 0.406] and [0.229, 0.224, 0.225].
If the input image does not have the same resolution as the native resolution (224x224 for all except ViT-L/14@336px, which has 336x336 resolution), then the input image is scaled down by bicubic interpolation, so that its shorter side is the same as the native resolution, then the central square of the image is cropped out.
Others
ALIGN used over one billion image-text pairs, obtained by extracting images and their alt-tags from online crawling. The method was described as similar to how the Conceptual Captions dataset was constructed, but instead of complex filtering, they only applied a frequency-based filtering.
Later models trained by other organizations had published datasets. For example, LAION trained OpenCLIP with published datasets LAION-400M, LAION-2B, and DataComp-1B.
Training
In the original OpenAI CLIP report, they reported training 5 ResNet and 3 ViT (ViT-B/32, ViT-B/16, ViT-L/14). Each was trained for 32 epochs. The largest ResNet model took 18 days to train on 592 V100 GPUs. The largest ViT model took 12 days on 256 V100 GPUs.
All ViT models were trained on 224x224 image resolution. The ViT-L/14 was then boosted to 336x336 resolution by FixRes, resulting in a model. They found this was the best-performing model.
In the OpenCLIP series, the ViT-L/14 model was trained on 384 A100 GPUs on the LAION-2B dataset, for 160 epochs for a total of 32B samples seen.
Applications
Cross-modal retrieval
CLIP's cross-modal retrieval enables the alignment of visual and textual data in a shared latent space, allowing users to retrieve images based on text descriptions and vice versa, without the need for explicit image annotations. In text-to-image retrieval, users input descriptive text, and CLIP retrieves images with matching embeddings. In image-to-text retrieval, images are used to find related text content.
CLIP’s ability to connect visual and textual data has found applications in multimedia search, content discovery, and recommendation systems.
Image classification
CLIP can perform zero-shot image classification tasks. This is achieved by prompting the text encoder with class names and selecting the class whose embedding is closest to the image embedding. For example, to classify an image, they compared the embedding of the image with the embedding of the text "A photo of a {class}.", and the {class} that results in the highest dot product is outputted.
CLIP for multimodal learning
CLIP has been used as a component in multimodal learning. For example, during the training of Google DeepMind's Flamingo (2022), the authors trained a CLIP pair, with BERT as the text encoder and NormalizerFree ResNet F6 as the image encoder. The image encoder of the CLIP pair was taken with parameters frozen and the text encoder was discarded. The frozen image encoder was then combined with a frozen Chinchilla language model, by finetuning with some further parameters that connect the two frozen models.
Applications in other domains
CLIP has been used in various domains beyond its original purpose:
Image Featurizer: CLIP's image encoder can be adapted as a pre-trained image featurizer. This can then be fed into other AI models.
Text-to-Image Generation: Models like Stable Diffusion use CLIP's text encoder to transform text prompts into embeddings for image generation. CLIP can also be used as a gradient signal for directly guiding diffusion ("CLIP guidance") or other generative art.
Aesthetic Ranking: Fine-tuned CLIP models can be used to rank images by aesthetic quality, aiding in dataset curation.
Image Captioning: CLIP can be used to generate image captions by matching text inputs to image embeddings.
Notes
References
External links
OpenAI's CLIP webpage
Machine learning
Artificial neural networks
Computer vision
Natural language processing | Contrastive Language-Image Pre-training | [
"Technology",
"Engineering"
] | 2,442 | [
"Machine learning",
"Packaging machinery",
"Natural language processing",
"Artificial intelligence engineering",
"Natural language and computing",
"Computer vision"
] |
67,219,853 | https://en.wikipedia.org/wiki/APWEN | The Association of Professional Women Engineers of Nigeria (APWEN) was established in 1982 by Nigerian engineer Joana Maduka. It is a division of the Nigerian Society of Engineers (NSE).
According to the body's leadership, APWEN was founded by six women and now has a membership of over 3,000 people with chapters in 35 cities, and collegiate in 16 campuses in all six geopolitical zones of Nigeria.
APWEN advocates the inclusion of females in the engineering sector, by educating them to contribute to the production sector of the economy.
The chairman of the Ota chapter, Dr. Imhade Okokpujie during the 2021/2022 executives' inauguration was quoted to have said, "Nigeria, as it stands, lacks involvement in that aspect of production engineering, hence the need to answer the question, 'What do Nigeria produce?' This is why women's development will be a catalyst for national development, hence, the need for more mentorship and encouragement for the girl child to study engineering."
APWEN advocates for more female representation in STEM courses and projects in the engineering field by organising programs that encourage young girls in high schools and colleges, as well as promote women considered prominent in various engineering fields. Some of their programs include scholarships to young females. The award programme is often in conjunction with other bodies and corporations.
References
Engineering organizations
Professional associations based in Nigeria
1982 establishments in Nigeria
Women in engineering | APWEN | [
"Engineering"
] | 290 | [
"nan"
] |
67,220,055 | https://en.wikipedia.org/wiki/Benjaminiella | Benjaminiella is a genus of fungi belonging to the family Mucoraceae.
The genus name of Benjaminiella is in honour of Richard Keith Benjamin (1922 - 2002), an American botanist from Rancho Santa Ana Botanic Garden.
Species:
Benjaminiella multispora Benny, Samson & M.C.Sriniv.
Benjaminiella poitrasii (R.K.Benj.) Arx
Benjaminiella youngii P.M.Kirk
References
Fungi
Fungus genera | Benjaminiella | [
"Biology"
] | 100 | [
"Fungi"
] |
67,221,648 | https://en.wikipedia.org/wiki/Introduction%20to%20Lattices%20and%20Order | Introduction to Lattices and Order is a mathematical textbook on order theory by Brian A. Davey and Hilary Priestley. It was published by the Cambridge University Press in their Cambridge Mathematical Textbooks series in 1990, with a second edition in 2002. The second edition is significantly different in its topics and organization, and was revised to incorporate recent developments in the area, especially in its applications to computer science. The Basic Library List Committee of the Mathematical Association of America has suggested its inclusion in undergraduate mathematics libraries.
Topics
Both editions of the book have 11 chapters; in the second book they are organized with the first four providing a general reference for mathematicians and computer scientists, and the remaining seven focusing on more specialized material for logicians, topologists, and lattice theorists.
The first chapter concerns partially ordered sets, with a fundamental example given by the partial functions ordered by the subset relation on their graphs, and covers fundamental concepts including top and bottom elements and upper and lower sets. These ideas lead to the second chapter, on lattices, in which every two elements (or in complete lattices, every set) has a greatest lower bound and a least upper bound. This chapter includes the construction of a lattice from the lower sets of any partial order, and the Knaster–Tarski theorem constructing a lattice from the fixed points of an order-preserving functions on a complete lattice. Chapter three concerns formal concept analysis, its construction of "concept lattices" from collections of objects and their properties, with each lattice element representing both a set of objects and a set of properties held by those objects, and the universality of this construction in forming complete lattices. The fourth of the introductory chapters concerns special classes of lattices, including modular lattices, distributive lattices, and Boolean lattices.
In the second part of the book, chapter 5 concerns the theorem that every finite Boolean lattice is isomorphic to the lattice of subsets of a finite set, and (less trivially) Birkhoff's representation theorem according to which every finite distributive lattice is isomorphic to the lattice of lower sets of a finite partial order. Chapter 6 covers congruence relations on lattices. The topics in chapter 7 include closure operations and Galois connections on partial orders, and the Dedekind–MacNeille completion of a partial order into the smallest complete lattice containing it. The next two chapters concern complete partial orders, their fixed-point theorems, information systems, and their applications to denotational semantics. Chapter 10 discusses order-theoretic equivalents of the axiom of choice, including extensions of the representation theorems from chapter 5 to infinite lattices, and the final chapter discusses the representation of lattices with topological spaces, including Stone's representation theorem for Boolean algebras and the duality theory for distributive lattices.
Two appendices provide background in topology needed for the final chapter, and an annotated bibliography.
Audience and reception
This book is aimed at beginning graduate students, although it could also be used by advanced undergraduates. Its many exercises make it suitable as a course textbook, and serve both to fill in details from the exposition in the book, and to provide pointers to additional topics. Although some mathematical sophistication is required of its readers, the main prerequisites are discrete mathematics, abstract algebra, and group theory.
Writing of the first edition, reviewer Josef Niederle calls it "an excellent textbook", "up-to-date and clear". Similarly, Thomas S. Blyth praises the first edition as "a well-written, satisfying, informative, and stimulating account of applications that are of great interest", and in an updated review writes that the second edition is as good as the first. Likewise, although Jon Cohen has some quibbles with the ordering and selection of topics (particularly the inclusion of congruences at the expense of a category-theoretic view of the subject), he concludes that the book is "a wonderful and accessible introduction to lattice theory, of equal interest to both computer scientists and mathematicians".
Both Blyth and Cohen note the book's skilled use of LaTeX to create its diagrams, and its helpful descriptions of how the diagrams were made.
References
Mathematics textbooks
Order theory
1990 non-fiction books
2002 non-fiction books | Introduction to Lattices and Order | [
"Mathematics"
] | 888 | [
"Order theory"
] |
67,222,418 | https://en.wikipedia.org/wiki/Ashlie%20Martini | Ashlie Martini is a tribologist and professor of mechanical engineering at University of California, Merced.
Biography
Education
Martini received her Bachelor of Science in mechanical engineering in 1998 from Northwestern University, in Evanston, Illinois. She later completed her Doctor of Philosophy in the same field, at the same school, in 2007.
Career
She was an assistant professor at Purdue University in West Lafayette, Indiana before becoming a full professor at University of California, Merced.
Research
The topics of study at "Martini Research Group: Fundamental Tribology Lab" at UC Merced include:
Solid and liquid lubricants
Tribochemistry
Nanoscale contact and sliding
Martini's lab helps test dry lubricants for the Mars rover. "The Martini research group is performing some very critical and important data gathering for us and presenting that data in a way that helps us make critical, mission-sensitive decisions for Mars," said Duval Johnson of NASA's Jet Propulsion Laboratory.
Awards and honors
American Society of Mechanical Engineers - ASME Burt L. Newkirk Award (2012)
Air Force Office of Scientific Research - AFOSR Young Investigator Award
Distinctions
Tribology Letters - Editor
Tribology Transactions - Associate Editor
Tribology International - Editorial Board Member
Computational Materials Science - Editorial Board Member
Lubricants - Editorial Board Member
Gordon Research Conference on Tribology (International Conference) - Chair
Society of Tribologists and Lubrication Engineers Tribology Frontiers Conference (International Conference) - Chair
Publications
Martini has over 250 publications. Her most cited work has been cited over 4400 times:
Her second most cited work has been cited over 400 times:
See also
Tribology
Mechanical engineering
ASME Burt L. Newkirk Award
Stick-slip phenomenon
References
External links
University of California, Merced faculty
Northwestern University alumni
American women scientists
American women engineers
Mechanical engineers
Tribologists
Living people
Year of birth missing (living people)
American women academics
21st-century American women | Ashlie Martini | [
"Materials_science",
"Engineering"
] | 397 | [
"Tribology",
"Mechanical engineers",
"Tribologists",
"Mechanical engineering"
] |
67,222,715 | https://en.wikipedia.org/wiki/Cerium%28III%29%20sulfide | Cerium(III) sulfide, also known as cerium sesquisulfide, is an inorganic compound with the formula Ce2S3. It is the sulfide salt of cerium(III) and exists as three polymorphs with different crystal structures.
Its high melting point (comparable to silica or alumina) and chemically inert nature have led to occasional examination of potential use as a refractory material for crucibles, but it has never been widely adopted for this application.
The distinctive red colour of two of the polymorphs (α- and β-Ce2S3) and aforementioned chemical stability up to high temperatures have led to some limited commercial use as a red pigment (known as cerium sulfide red).
Synthesis
The oldest syntheses reported for cerium(III) sulfide follow a typical rare earth sesquisulfide formation route, which involves heating the corresponding cerium sesquioxide to 900–1100 °C in an atmosphere of hydrogen sulfide:
Ce2O3 + 3 H2S → Ce2S3 + 3 H2O
Newer synthetic procedures utilise less toxic carbon disulfide gas for sulfurisation, starting from cerium dioxide which is reduced by the CS2 gas at temperatures of 800–1000 °C:
6 CeO2 + 5 CS2 → 3 Ce2S3 + 5 CO2 + SO2
Polymorphs
Ce2S3 exists in three polymorphic forms: α-Ce2S3 (orthorhombic, burgundy colour), β-Ce2S3 (tetragonal, red colour), γ-Ce2S3 (cubic, black colour). They are analogous to the crystal structures of the likewise trimorphic Pr2S3 and Nd2S3.
Following the synthetic procedures given above will yield mostly the α- and β- polymorphs, with the proportion of α-Ce2S3 increasing at lower temperatures (~700–900 °C) and with longer reaction times. The α- form can be irreversibly transformed into β-Ce2S3 by vacuum heating at 1200 °C for 7 hours. Then γ-Ce2S3 is obtained from sintering of β-Ce2S3 powder via hot pressing at an even higher temperature (1700 °C).
α polymorph
The α polymorph of cerium(III) sulfide has the same structure as α-. It contains both 7-coordinate and 8-coordinate cerium ions, , with monocapped and bicapped trigonal prismatic coordination geometry, respectively. The sulfide ions, , are 5-coordinate. Two thirds of them adopt a square pyramidal geometry and one third adopt a trigonal bipyramidal geometry.
γ polymorph
The γ polymorph of cerium(III) sulfide adopts a cation-deficient form of the structure. 8 out the 9 metal positions in the structure are occupied by cerium in γ-, with the remainder as vacancies. This composition can be represented by the formula . The cerium ions are 8-coordinate while the sulfide ions are 6-coordinate (distorted octahedral).
Reactions
Some reported reactions of cerium(III) sulfide are with bismuth compounds in order to form superconducting crystalline materials of the M(O,F)BiS2 family (for M=Ce).
The reaction of Ce2S3 with Bi2S3 and Bi2O3 in a sealed tube at 950 °C gives the parent compound CeOBiS2:
3 Ce2S3 + Bi2S3 + 2 Bi2O3 → 6 CeOBiS2
This material is superconducting on its own, but the properties can be enhanced if it is doped with fluoride by including BiF3 in the reaction mixture.
Applications
Refractory material
Cerium(III) and cerium(IV) sulfides were first investigated in the 1940s as part of the Manhattan project, where they were considered -but eventually not adopted- as advanced refractory materials. Their suggested application was as the material in crucibles for the casting of uranium and plutonium metal.
Although the sulfide's properties (high melting point and large, large negative ΔfG° and chemical inertness) are suitable and cerium is a relatively common element (66 ppm, about as much as copper), the danger of the traditional H2S-involving production route and the difficulty in controlling the formation of the resulting Ce2S3/CeS solid mixture meant that the compound was ultimately not developed further for such applications.
Pigment and other uses
The main non-research use of cerium(III) sulfide is as a specialty inorganic pigment. The strong red hues of α- and β-Ce2S3, non-prohibitive cost of cerium, and chemically inert behaviour up to high temperature are the factors which make the compound desirable as a pigment.
Regarding other applications, the γ-Ce2S3 polymorph has a band gap of 2.06 eV and high Seebeck coefficient, thus it has been proposed as a high-temperature semiconductor for thermoelectric generators. A practical implementation thereof has not been demonstrated so far.
References
Sesquisulfides
Cerium(III) compounds
Refractory materials
Inorganic pigments | Cerium(III) sulfide | [
"Physics",
"Chemistry"
] | 1,113 | [
"Inorganic compounds",
"Refractory materials",
"Inorganic pigments",
"Materials",
"Matter"
] |
64,250,278 | https://en.wikipedia.org/wiki/Timeout%20Detection%20and%20Recovery | Timeout Detection and Recovery or TDR is a feature of the Windows operating system (OS) introduced in Windows Vista. It detects response problems from a graphics card (GPU), and if a timeout occurs, the OS will attempt a card reset to recover a functional and responsive desktop environment. However, if the attempt was unsuccessful, it results in the Blue Screen of Death (BSOD). The recovery tries to mitigate the scenario where an end user superfluously reboots their device should it become unresponsive.
Timeline
When the GPU takes more than the allotted time to process a request, the system's GPU scheduler will pick up the anomaly. It then tries to preempt the particular task, this operation has the TDR timeout which is 2 seconds by default.
Once the timeout is up and the task is not completed or preempted, the kernel determines that the GPU is frozen and proceeds to inform the respective driver about the detected timeout. It is then the driver's responsibility to properly reset and reinitialize the underlying GPU.
The OS will then do a bunch of other recovery steps needed for the system to regain responsiveness. If the entire operation was successful, the end user might see some visual artefacts and a message will be shown on the screen describing what had happened ("Display driver stopped responding and has recovered."), else a BSOD might ensue.
Possible causes
There are multiple probable causes should a recovery fail, causing an inevitable BSOD:
Outdated drivers
GPU/Hardware issue
Overloading the GPU
Corrupted application/system files/driver
BSOD stop codes
Possible BSOD stop codes emitted if the attempted recovery failed:
VIDEO_TDR_FAILURE (Bug check value: 0x116), recovery and resetting of display driver from a TDR timeout failed.
See also
Windows Display Driver Model
Display driver
DirectX
Vulkan
References
Further reading
Timeout Detection & Recovery (TDR) Nvidia
TDR in Windows 8 and later - Windows drivers | Microsoft Learn
Thread Synchronization and TDR - Windows drivers | Microsoft Learn
Microsoft Windows | Timeout Detection and Recovery | [
"Technology"
] | 441 | [
"Computing platforms",
"Microsoft Windows"
] |
64,252,606 | https://en.wikipedia.org/wiki/Garbage%20landslide | A garbage landslide is a man-made event that occurs when poorly managed garbage mounds at landfills collapse with similar energy to natural landslides. These kinds of slides can be catastrophic as they sometimes occur near communities of people, often being triggered by weather or human interaction. This form of landslide has attracted the attention of anthropologists, news media, and politicians as a result of incidents that have severely damaged communities and killed hundreds of people since the 1990s.
Causes
People and weather can cause garbage landslides by impacting the weight distribution of mounds in landfills, which are sometimes poorly regulated and open to those seeking recyclables for profit. Human interaction can destabilize precarious mounds of garbage as people walk atop them or attempt to remove valuable materials. Such dangerous mounds are frequently found on slopes and hillsides, where landfills often exist due to the lack of value for other development. Impoverished communities may be drawn to build homes near such landfills for extant recycling opportunities, and informal neighborhoods have developed in high-risk areas as a result. People collecting garbage are thus commonly both triggers and victims of garbage landslides, but these events can also be caused by landfill workers driving heavy machinery nearby or adding too much trash to the mounds.
Weather is a common agitator and cause of garbage landslides. Mounds may collapse if they become heavier from rain and disturbances like strong storms can both trigger sliding and start fires if lightning ignites combustible gases from the landfill. Weather may also induce soil erosion, making landfills more vulnerable to sliding events.
Government mismanagement
Landfill mismanagement and public corruption have featured as significant factors to devastating garbage landslides. If layers of garbage are not properly buried, they remain loose and can gradually separate from the effects of weather and people. Poor waste management policies of different governments at local and national levels contribute to a lack of regulation enabling irresponsible dumping and hazardous access to landfills. Poverty in a society is a very important risk factor as the lack of more stable income can motivate people to collect recyclables from or live in such hazardous sites. As of 2017, around 15 million people lived and worked within such landfills.
Notable examples
Several garbage landslides have occurred worldwide since the 1990s in which nearby infrastructure was destroyed or mass casualties occurred. Examples from the 90s include a 1993 methane explosion at a landfill in Istanbul's Ümraniye district, which triggered a landslide that killed 30 people, and a 1996 garbage slide in Ohio at the Colerain Township landfill which destroyed an adjacent limestone quarry. The latter landslide resulted in a 35-acre fire after lightning ignited combustible waste fumes.
These accidents have become more common and more deadly in the twenty-first century. On 21 July 2000 a garbage mound at the Payatas Sanitary Landfill collapsed and slid through the barangay of Payatas outside Quezon City, Philippines, which resulted in the deaths of over 300 people. The tragedy resulted in the Philippine Congress banning all open-air garbage dumps throughout the country. Urban settings can also be affected by these events: During the 2015 Shenzhen landslide a 100-meter tall garbage mound collapsed into a slide and destroyed 33 buildings, some of them multistoried concrete structures, in the Hengtaiyu Industrial Park of Shenzhen in addition to rupturing part of the West–East Gas Pipeline. 45 individuals ultimately faced charges for the disaster and 20 public officials who oversaw the creation and management of the Shenzhen landfill later received prison sentences for corruption.
Incidents such as the aforementioned slides attracted local and international outcry, but many smaller events occasionally strike communities with fatal results and attract little media attention. As populations rise, the volumes of waste that need to be managed grow with them and raise the risk of deadly accidents occurring. The development of communities around poorly-managed landfills has left some populations increasingly vulnerable to garbage landslides, which accounted for 15% of landslides not involving soil or rocks from 1993-2004.
See also
2005 Leuwigajah landslide
References
Landslides
Landfill | Garbage landslide | [
"Environmental_science"
] | 812 | [
"Landslides",
"Environmental soil science"
] |
64,252,681 | https://en.wikipedia.org/wiki/Samsung%20Galaxy%20Z%20Fold%202 | The Samsung Galaxy Z Fold 2 (stylized as Samsung Galaxy Z Fold2, sold as Samsung Galaxy Fold 2 in certain territories) is an Android-based foldable smartphone developed by Samsung Electronics for its Samsung Galaxy Z series, succeeding the Samsung Galaxy Fold. It was announced on 5 August 2020 alongside the Samsung Galaxy Note 20, the Samsung Galaxy Tab S7, the Galaxy Buds Live, and the Galaxy Watch 3. Samsung later revealed pricing and availability details on 1 September.
On October 9, 2024, Samsung stopped security updates to the phone.
Specifications
Design
Unlike the original Fold which had an entirely plastic screen, the screen is protected by -thick "ultra-thin glass" with a plastic layer like the Z Flip, manufactured by Samsung with materials from Schott AG; conventional Gorilla Glass is used for the back panels with an aluminum frame. The hinge mechanism is also borrowed from the Z Flip, using nylon fibers designed to keep dust out; it is self-supporting from 75 to 115 degrees. The power button is embedded in the frame and doubles as the fingerprint sensor, with the volume rocker located above. The device comes in two colors, Mystic Bronze and Mystic Black, as well as a Limited Edition Thom Browne model. In select regions, users are able to customize the hinge color when ordering the phone from Samsung's website.
Hardware
The Galaxy Z Fold 2 contains two screens: its front cover uses a 6.2-inch display in the center with minimal bezels, significantly larger than its predecessor's 4.6-inch display, and the device can fold open to expose a 7.6-inch display, with a circular cutout in the top center right replacing the notch along with a thinner border. Both displays support HDR10+; the internal display benefits from an adaptive 120 Hz refresh rate like the S20 series and Note 20 Ultra.
The device has 12 GB of LPDDR5 RAM, and either 256 or 512 GB of non-expandable UFS 3.1. Storage availability varies by country, the 512 GB version is the most scarce by far. The Z Fold 2 is powered by the Qualcomm Snapdragon 865+, which is used in all regions (unlike other flagship Samsung phones that have been split between Snapdragon and Samsung's in-house Exynos chips depending on the market). It uses two batteries split between the two halves, totaling a slightly larger 4500 mAh capacity; fast charging is supported over USB-C at up to 25 W or wirelessly via Qi at up to 11 W. The Z Fold 2 contains 5 cameras, including three rear-facing camera lenses (12-megapixel, 12-megapixel telephoto, and 12-megapixel ultra wide-angle), as well as a 10-megapixel front-facing camera on the cover, and a second 10-megapixel front-facing camera on the inside screen.
Software
The Galaxy Z Fold 2 shipped with Android 10 and Samsung's One UI software; by means of an improved Multi Window mode, up to three supported apps can be placed on-screen at once. Apps open on the smaller screen can expand into their larger, tablet-oriented layouts when the user unfolds the device. Additionally, supported apps will now automatically get a split-screen view with a sidebar and main app pane. New to the Z Fold 2 is split-screen functionality, called "Flex Mode", which is compatible with certain apps like YouTube and Google Duo along with native Samsung apps.
Luxury model
In November 2020, Samsung unveiled the Samsung W21 5G, a luxury version of the Z Fold2, exclusively available to the Chinese market. The phone is identical to its counterparts, in terms of its design and specifications, with the exception of a slightly taller build and two SIM card slots. The phone features an exclusive "Glitter Gold" color, which consists of a seven-layer nano-level optical film attached to the glass back that has vertical ridges for added texture.
Gallery
See also
Samsung Galaxy Z series
Samsung Galaxy Z Flip
References
External links
Samsung Galaxy
Foldable smartphones
Mobile phones introduced in 2020
Mobile phones with multiple rear cameras
Mobile phones with 4K video recording
Discontinued flagship smartphones
Discontinued Samsung Galaxy smartphones
Samsung smartphones | Samsung Galaxy Z Fold 2 | [
"Technology"
] | 882 | [
"Crossover devices",
"Foldable smartphones",
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64,256,623 | https://en.wikipedia.org/wiki/BitFunnel | BitFunnel is the search engine indexing algorithm and a set of components used in the Bing search engine, which were made open source in 2016. BitFunnel uses bit-sliced signatures instead of an inverted index in an attempt to reduce operations cost.
History
Progress on the implementation of BitFunnel was made public in early 2016, with the expectation that there would be a usable implementation later that year. In September 2016, the source code was made available via GitHub. A paper discussing the BitFunnel algorithm and implementation was released as through the Special Interest Group on Information Retrieval of the Association for Computing Machinery in 2017 and won the Best Paper Award.
Components
BitFunnel consists of three major components:
BitFunnel – the text search/retrieval system itself
WorkBench – a tool for preparing text for use in BitFunnel
NativeJIT – a software component that takes expressions that use C data structures and transforms them into highly optimized assembly code
Algorithm
Initial problem and solution overview
The BitFunnel paper describes the "matching problem", which occurs when an algorithm must identify documents through the usage of keywords. The goal of the problem is to identify a set of matches given a corpus to search and a query of keyword terms to match against. This problem is commonly solved through inverted indexes, where each searchable item is maintained with a map of keywords.
In contrast, BitFunnel represents each searchable item through a signature. A signature is a sequence of bits which describe a Bloom filter of the searchable terms in a given searchable item. The bloom filter is constructed through hashing through several bit positions.
Theoretical implementation of bit-string signatures
The signature of a document (D) can be described as the logical-or of its term signatures:
Similarly, a query for a document (Q) can be defined as a union:
Additionally, a document D is a member of the set M''' when the following condition is satisfied:
This knowledge is then combined to produce a formula where M''' is identified by documents which match the query signature:
These steps and their proofs are discussed in the 2017 paper.
Pseudocode for bit-string signatures
This algorithm is described in the 2017 paper.
References
External links
BitFunnel · GitHub
BitFunnel · BitFunnel
Data management
Search algorithms
Database index techniques
Free and open-source software
Microsoft free software
Microsoft Research
Software using the MIT license
Free software programmed in C++ | BitFunnel | [
"Technology"
] | 510 | [
"Data management",
"Data"
] |
64,257,772 | https://en.wikipedia.org/wiki/Laguerre%20transformations | The Laguerre transformations or axial homographies are an analogue of Möbius transformations over the dual numbers. When studying these transformations, the dual numbers are often interpreted as representing oriented lines on the plane. The Laguerre transformations map lines to lines, and include in particular all isometries of the plane.
Strictly speaking, these transformations act on the dual number projective line, which adjoins to the dual numbers a set of points at infinity. Topologically, this projective line is equivalent to a cylinder. Points on this cylinder are in a natural one-to-one correspondence with oriented lines on the plane.
Definition
A Laguerre transformation is a linear fractional transformation where are all dual numbers, lies on the dual number projective line, and is not a zero divisor.
A dual number is a hypercomplex number of the form where but . This can be compared to the complex numbers which are of the form where .
The points of the dual number projective line can be defined equivalently in two ways:
The usual set of dual numbers, but with some additional "points at infinity". Formally, the set is . The points at infinity can be expressed as where is an arbitrary real number. Different values of correspond to different points at infinity. These points are infinite because is often understood as being an infinitesimal number, and so is therefore infinite.
The homogeneous coordinates [x : y] with x and y dual numbers such that the ideal that they generate is the whole ring of dual numbers. The ring is viewed through the injection x ↦ [x : 1]. The projective line includes points [1 : yε].
Line coordinates
A line which makes an angle with the x-axis, and whose x-intercept is denoted , is represented by the dual number
The above doesn't make sense when the line is parallel to the x-axis. In that case, if then set where is the y-intercept of the line. This may not appear to be valid, as one is dividing by a zero divisor, but this is a valid point on the projective dual line. If then set .
Finally, observe that these coordinates represent oriented lines. An oriented line is an ordinary line with one of two possible orientations attached to it. This can be seen from the fact that if is increased by then the resulting dual number representative is not the same.
Matrix representations
It's possible to express the above line coordinates as homogeneous coordinates where is the perpendicular distance of the line from the origin. This representation has numerous advantages: One advantage is that there is no need to break into different cases, such as parallel to the -axis and non-parallel. The other advantage is that these homogeneous coordinates can be interpreted as vectors, allowing us to multiply them by matrices.
Every Laguerre transformation can be represented as a 2×2 matrix whose entries are dual numbers. The matrix representation of is (but notice that any non-nilpotent scalar multiple of this matrix represents the same Laguerre transformation). Additionally, as long as the determinant of a 2×2 matrix with dual-number entries is not nilpotent, then it represents a Laguerre transformation.
(Note that in the above, we represent the homogeneous vector as a column vector in the obvious way, instead of as a row vector.)
Points, oriented lines and oriented circles
Laguerre transformations do not act on points. This is because if three oriented lines pass through the same point, their images under a Laguerre transformation do not have to meet at one point.
Laguerre transformations can be seen as acting on oriented lines as well as on oriented circles. An oriented circle is an ordinary circle with an orientation represented by a binary value attached to it, which is either or . The only exception is a circle of radius zero, which has orientation equal to . A point is defined to be an oriented circle of radius zero. If an oriented circle has orientation equal to , then the circle is said to be "anti-clockwise" oriented; if it has orientation equal to then it is "clockwise" oriented. The radius of an oriented circle is defined to be the radius of the underlying unoriented circle multiplied by the orientation.
The image of an oriented circle under a Laguerre transformation is another oriented circle. If two oriented figures – either circles or lines – are tangent to each other then their images under a Laguerre transformation are also tangent. Two oriented circles are defined to be tangent if their underlying circles are tangent and their orientations are equal at the point of contact. Tangency between lines and circles is defined similarly. A Laguerre transformation might map a point to an oriented circle which is no longer a point.
An oriented circle can never be mapped to an oriented line. Likewise, an oriented line can never be mapped to an oriented circle. This is opposite to Möbius geometry, where lines and circles can be mapped to each other, but neither can be mapped to points. Both Möbius geometry and Laguerre geometry are subgeometries of Lie sphere geometry, where points and oriented lines can be mapped to each other, but tangency remains preserved.
The matrix representations of oriented circles (which include points but not lines) are precisely the invertible skew-Hermitian dual number matrices. These are all of the form (where all the variables are real, and ). The set of oriented lines tangent to an oriented circle is given by where denotes the projective line over the dual numbers . Applying a Laguerre transformation represented by to the oriented circle represented by gives the oriented circle represented by . The radius of an oriented circle is equal to the half the trace. The orientation is then the sign of the trace.
Profile
Note that the animated figures below show some oriented lines, but without any visual indication of a line's orientation (so two lines that differ only in orientation are displayed in the same way); oriented circles are shown as a set of oriented tangent lines, which results in a certain visual effect.
The following can be found in Isaak Yaglom's Complex numbers in geometry and a paper by Gutin entitled Generalizations of singular value decomposition to dual-numbered matrices.
Unitary matrices
Mappings of the form express rigid body motions (sometimes called direct Euclidean isometries). The matrix representations of these transformations span a subalgebra isomorphic to the planar quaternions.
The mapping represents a reflection about the x-axis.
The transformation expresses a reflection about the y-axis.
Observe that if is the matrix representation of any combination of the above three transformations, but normalised so as to have determinant , then satisfies where means . We will call these unitary matrices. Notice though that these are unitary in the sense of the dual numbers and not the complex numbers. The unitary matrices express precisely the Euclidean isometries.
Axial dilation matrices
An axial dilation by units is a transformation of the form . An axial dilation by units increases the radius of all oriented circles by units while preserving their centres. If a circle has negative orientation, then its radius is considered negative, and therefore for some positive values of the circle actually shrinks. An axial dilation is depicted in Figure 1, in which two circles of opposite orientations undergo the same axial dilation.
On lines, an axial dilation by units maps any line to a line such that and are parallel, and the perpendicular distance between and is . Lines that are parallel but have opposite orientations move in opposite directions.
Real diagonal matrices
The transformation for a value of that's real preserves the x-intercept of a line, while changing its angle to the x-axis. See Figure 2 to observe the effect on a grid of lines (including the x axis in the middle) and Figure 3 to observe the effect on two circles that differ initially only in orientation (to see that the outcome is sensitive to orientation).
A general decomposition
Putting it all together, a general Laguerre transformation in matrix form can be expressed as where and are unitary, and is a matrix either of the form or where and are real numbers. The matrices and express Euclidean isometries. The matrix either represents a transformation of the form or an axial dilation. The resemblance to Singular Value Decomposition should be clear.
Note: In the event that is an axial dilation, the factor can be set to the identity matrix. This follows from the fact that if is unitary and is an axial dilation, then it can be seen that , where denotes the transpose of . So .
Other number systems and the parallel postulate
Complex numbers and elliptic geometry
A question arises: What happens if the role of the dual numbers above is changed to the complex numbers? In that case, the complex numbers represent oriented lines in the elliptic plane (the plane which elliptic geometry takes places over). This is in contrast to the dual numbers, which represent oriented lines in the Euclidean plane. The elliptic plane is essentially a sphere (but where antipodal points are identified), and the lines are thus great circles. We can choose an arbitrary great circle to be the equator. The oriented great circle which intersects the equator at longitude , and makes an angle with the equator at the point of intersection, can be represented by the complex number . In the case where (where the line is literally the same as the equator, but oriented in the opposite direction as when ) the oriented line is represented as . Similar to the case of the dual numbers, the unitary matrices act as isometries of the elliptic plane. The set of "elliptic Laguerre transformations" (which are the analogues of the Laguerre transformations in this setting) can be decomposed using Singular Value Decomposition of complex matrices, in a similar way to how we decomposed Euclidean Laguerre transformations using an analogue of Singular Value Decomposition for dual-number matrices.
Split-complex numbers and hyperbolic geometry
If the role of the dual numbers or complex numbers is changed to the split-complex numbers, then a similar formalism can be developed for representing oriented lines on the hyperbolic plane instead of the Euclidean or elliptic planes: A split-complex number can be written in the form because the algebra in question is isomorphic to . (Notice though that as a *-algebra, as opposed to a mere algebra, the split-complex numbers are not decomposable in this way). The terms and in represent points on the boundary of the hyperbolic plane; they are respectively the starting and ending points of an oriented line. Since the boundary of the hyperbolic plane is homeomorphic to the projective line , we need and to belong to the projective line instead of the affine line . Indeed, this hints that .
The analogue of unitary matrices over the split-complex numbers are the isometries of the hyperbolic plane. This is shown by Yaglom. Furthermore, the set of linear fractional transformations can be decomposed in a way that resembles Singular Value Decomposition, but which also unifies it with the Jordan decomposition.
Summary
We therefore have a correspondence between the three planar number systems (complex, dual and split-complex numbers) and the three non-Euclidean geometries. The number system that corresponds to Euclidean geometry is the dual numbers.
In higher dimensions
Euclidean
n-dimensional Laguerre space is isomorphic to n + 1 Minkowski space. To associate a point in Minkowski space to an oriented hypersphere, intersect the light cone centred at with the hyperplane. The group of Laguerre transformations is isomorphic then to the Poincaré group . These transformations are exactly those which preserve a kind of squared distance between oriented circles called their Darboux product. The direct Laguerre transformations are defined as the subgroup . In 2 dimensions, the direct Laguerre transformations can be represented by 2×2 dual number matrices. If the 2×2 dual number matrices are understood as constituting the Clifford algebra , then analogous Clifford algebraic representations are possible in higher dimensions.
If we embed Minkowski space in the projective space while keeping the transformation group the same, then the points at infinity are oriented flats. We call them "flats" because their shape is flat. In 2 dimensions, these are the oriented lines.
As an aside, there are two non-equivalent definitions of a Laguerre transformation: Either as a Lie sphere transformation that preserves oriented flats, or as a Lie sphere transformation that preserves the Darboux product. We use the latter convention in this article. Note that even in 2 dimensions, the former transformation group is more general than the latter: A homothety for example maps oriented lines to oriented lines, but does not in general preserve the Darboux product. This can be demonstrated using the homothety centred at by units. Now consider the action of this transformation on two circles: One simply being the point , and the other being a circle of raidus centred at . These two circles have a Darboux product equal to . Their images under the homothety have a Darboux product equal to . This therefore only gives a Laguerre transformation when .
Conformal interpretation
In this section, we interpret Laguerre transformations differently from in the rest of the article. When acting on line coordinates, Laguerre transformations are not understood to be conformal in the sense described here. This is clearly demonstrated in Figure 2.
The Laguerre transformations preserve angles when the proper angle for the dual number plane is identified. When a ray , , and the positive x-axis are taken for sides of an angle, the slope m is the magnitude of this angle.
This number m corresponds to the signed area of the right triangle with base on the interval . The line , with the dual number multiplication, forms a subgroup of the unit dual numbers, each element being a shear mapping when acting on the dual number plane. Other angles in the plane are generated by such action, and since shear mapping preserves area, the size of these angles is the same as the original.
Note that the inversion z to 1/z leaves angle size invariant. As the general Laguerre transformation is generated by translations, dilations, shears, and inversions, and all of these leave angle invariant, the general Laguerre transformation is conformal in the sense of these angles.
See also
Edmond Laguerre
Laguerre plane
Isaak Yaglom
Line coordinates
References
Lie groups
Functions and mappings
Projective geometry
Hypercomplex numbers
Geometry
External links
"Oriented circles and 3D relativistic geometry" An elementary video introducing concepts in Laguerre geometry. The video is presented from the rational trigonometry perspective | Laguerre transformations | [
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"Lie groups",
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"Hypercomplex numbers",
"Numbers"
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64,258,213 | https://en.wikipedia.org/wiki/Polygonalization | In computational geometry, a polygonalization of a finite set of points in the Euclidean plane is a simple polygon with the given points as its vertices. A polygonalization may also be called a polygonization, simple polygonalization, Hamiltonian polygon, non-crossing Hamiltonian cycle, or crossing-free straight-edge spanning cycle.
Every point set that does not lie on a single line has at least one polygonalization, which can be found in polynomial time. For points in convex position, there is only one, but for some other point sets there can be exponentially many. Finding an optimal polygonalization under several natural optimization criteria is a hard problem, including as a special case the travelling salesman problem. The complexity of counting all polygonalizations remains unknown.
Definition
A polygonalization is a simple polygon having a given set of points in the Euclidean plane as its set of vertices. A polygon may be described by a cyclic order on its vertices, which are connected in consecutive pairs by line segments, the edges of the polygon. A polygon, defined in this way, is "simple" if the only intersection points of these line segments are at shared endpoints.
Some authors only consider polygonalizations for points that are in general position, meaning that no three are on a line. With this assumption, the angle between two consecutive segments of the polygon cannot be 180°. However, when point sets with collinearities are considered, it is generally allowed for their polygonalizations to have 180° angles at some points. When this happens, these points are still considered to be vertices, rather than being interior to edges.
Existence
observed that every finite point set with no three in a line forms the vertices of a simple polygon. However, requiring no three to be in a line is unnecessarily strong. Instead, all that is required for the existence of a polygonalization (allowing 180° angles) is that the points do not all lie on one line. If they do not, then they have a polygonalization that can be constructed in polynomial time. One way of constructing a polygonalization is to choose any point in the convex hull of (not necessarily one of the given points). Then radially ordering the points around (breaking ties by distance from q) produces the cyclic ordering of a star-shaped polygon through all the given points, with in its kernel. The same idea of sorting points radially around a central point is used in some versions of the Graham scan convex hull algorithm, and can be performed in time. Polygonalizations that avoid 180° angles do not always exist. For instance, for and square grids, all polygonalizations use 180° angles.
As well as star-shaped polygonalizations, every non-collinear set of points has a polygonalization that is a monotone polygon. This means that, with respect to some straight line (which may be taken as the -axis) every perpendicular line to the reference line intersects the polygon in a single interval, or not at all. A construction of begins by sorting the points by their -coordinates, and drawing a line through the two extreme points. Because the points are not all in a line, at least one of the two open halfplanes bounded by this line must be non-empty. Grünbaum forms two monotone polygonal chains connecting the extreme points through sorted subsequences of the points: one for the points in this non-empty open halfplane, and the other for the remaining points. Their union is the desired monotone polygon. After the sorting step, the rest of the construction may be performed in linear time.
It is NP-complete to determine whether a set of points has a polygonalization using only axis-parallel edges. However, polygonalizations with the additional constraint that they make a right turn at every vertex, if they exist, are uniquely determined. Each axis-parallel line through a point must pass through an even number of points, and this polygonalization must connect alternating pairs of points on this line. The polygonalization may be found in time by grouping the points by equal coordinates and sorting each group by the other coordinate. For any point set, at most one rotation can have a polygonalization of this form, and this rotation can again be found in polynomial time.
Optimization
Problems of finding an optimal polygonalization (for various criteria of optimality) are often computationally infeasible. For instance, the solution to the travelling salesman problem, for the given points, does not have any crossings. Therefore, it is always a polygonalization, the polygonalization with the minimum perimeter. It is NP-hard to find. Similarly, finding the simple polygonalization with minimum or maximum area is known to be NP-hard, and has been the subject of some computational efforts. The maximum area is always more than half of the area of the convex hull, giving an approximation ratio of 2. The exact complexity of the simple polygonalization with maximum perimeter, and the existence of a constant approximation ratio for this problem, remain unknown. The polygonalization that minimizes the length of its longest edge is also NP-hard to find, and hard to approximate to an approximation ratio better than ; no constant-factor approximation is known.
A non-optimal solution to the travelling salesman problem may have crossings, but it is possible to eliminate all crossings by local optimization steps that reduce the total length. Using steps that also eliminate crossings at each step, this can be done in polynomial time, but without this restriction there exist local optimization sequences that instead use an exponential number of steps.
The shortest bitonic tour (the minimum-perimeter monotone polygon through the given points) is always a polygonalization, and can be found in polynomial time.
Counting
The problem of counting all polygonalizations of a given point set belongs to #P, the class of counting problems associated with decision problems in NP. However, it is unknown whether it is #P-complete or, if not, what its computational complexity might be. A set of points has exactly one polygonalization if and only if it is in convex position. There exist sets of points for which the number of polygonalizations is as large as , and every set of points has at most polygonalizations.
Methods applying the planar separator theorem to labeled triangulations of the points can be used to count all polygonalizations of a set of points in subexponential time, . Dynamic programming can be used to count all monotone polygonalizations in polynomial time, and the results of this computation can then be used to generate a random monotone polygonalization.
Generation
It is unknown whether it is possible for the system of all polygonalizations to form a connected state space under local moves that change a bounded number of the edges of the polygonalizations. If this were possible, it could be used as part of an algorithm for generating all polygonalizations, by applying a graph traversal to the state space. For this problem, it is insufficient to consider flips that remove two edges of a polygonalization and replace them by two other edges, or VE-flips that remove three edges, two of which share a vertex, and replace them by three other edges. There exist polygonalizations for which no flip or VE-flip is possible, even though the same point set has other polygonalizations.
The polygonal wraps, weakly simple polygons that use each given point one or more times as a vertex, include all polygonalizations and are connected by local moves. Another more general class of polygons, the surrounding polygons, are simple polygons that have some of the given points as vertices and enclose all of the points. They are again locally connected, and can be listed in polynomial time per polygon. The algorithm constructs a tree of polygons, with the convex hull as its root and with the parent of each other surrounding polygon obtained by removing one vertex (proven to be possible by applying the two ears theorem to the exterior of the polygon). It then applies a reverse-search algorithm to this tree to list the polygons. As a consequence of this method, all polygonalizations can be listed in exponential time ( for points) and polynomial space.
Applications
Classical connect the dots puzzles involve connecting points in sequence to form some unexpected shape, often without crossings. The travelling salesman problem and its variants have many applications. Polygonalization also has applications in the reconstruction of contour lines from scattered data points, and in boundary tracing in image analysis.
See also
Denjoy–Riesz theorem, on sets of infinitely many points that can be connected by a Jordan arc
References
Polygons
Computational geometry | Polygonalization | [
"Mathematics"
] | 1,801 | [
"Computational geometry",
"Computational mathematics"
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64,258,653 | https://en.wikipedia.org/wiki/Contact%20region | A Contact Region is a concept in robotics which describes the region between an object and a robot’s end effector. This is used in object manipulation planning, and with the addition of sensors built into the manipulation system, can be used to produce a surface map or contact model of the object being grasped.
In Robotics
For a robot to autonomously grasp an object, it is necessary for the robot to have an understanding of its own construction and movement capabilities (described through the math of inverse kinematics), and an understanding of the object to be grasped. The relationship between these two is described through a contact model, which is a set of the potential points of contact between the robot and the object being grasped. This, in turn, is used to create a more concrete mathematical representation of the grasp to be attempted, which can then be computed through path planning techniques and executed.
In Mathematics
Depending on the complexity of the end effector, or through usage of external sensors such as a Lidar or Depth camera, a more complex model of the planes involved in the object being grasped can be produced. In particular, sensors embedded in the fingertips of an end effector have been demonstrated to be an effective approach for producing a surface map from a given contact region. Through knowledge of the robot's position of each individual finger, the location of the sensors in each finger, and the amount of force being exerted by the object onto each sensor, points of contact can be calculated. These points of contact can then be turned into a three-dimensional ellipsis, producing a surface map of the object.
Applications
In hand manipulation is a typical use case. A robot hand interacts with static and deformable objects, described with soft-body dynamics. Sometimes, additional tools has to be controlled by the robot hand for example a screwdriver. Such interaction produces a complex situation in which the robot hand has similar contact points with the tool.
Apart from robotics control, tactile models are calculated in virtual environments. If a human operator touches with a data glove on an object, he produces a heatmap on the contact points with the object. This surface can be displayed in realtime and allows a better understanding of motion models.
References
Object manipulation
Robotics engineering | Contact region | [
"Technology",
"Engineering",
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"Behavior",
"Computer engineering",
"Robotics engineering",
"Motor control",
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64,260,042 | https://en.wikipedia.org/wiki/SCH-79797 | SCH-79797 is a drug which acts as a potent and selective antagonist of the thrombin receptor proteinase activated receptor 1 (PAR1). It has anticoagulant, anticonvulsant and antiinflammatory effects and has been researched as a treatment for heart attack and stroke, though never developed for medical use. It also shows antibiotic actions which are not shared with other PAR1 antagonists such as vorapaxar, so may be mediated through a different target than PAR1.
References
Antibiotics | SCH-79797 | [
"Chemistry",
"Biology"
] | 115 | [
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"Antibiotics",
"Pharmacology stubs",
"Biocides"
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60,756,169 | https://en.wikipedia.org/wiki/Caffeine%20use%20for%20sport | Caffeine use for sport is a worldwide known and tested idea. Many athletes use caffeine as a legal performance enhancer, as the benefits it provides, both physically and cognitively outweigh the disadvantages. The benefits caffeine provides influences the performance of both endurance athletes and anaerobic athletes. Caffeine has been proven to be effective in enhancing performance.
Caffeine is a stimulant drug. Once consumed, it is absorbed in the stomach and small intestine as well as being circulated throughout the body. It targets muscles and organs, in particular the brain.
Caffeine is most commonly known for being in coffee. It is also found in tea, chocolate, soft drinks, energy drinks and medications.
The short term effects from caffeine are usually noticed after 5–30 minutes and long term ones last for up to 12 hours.
Those who use caffeine regularly, most often drinking at least one coffee a day, can become dependent and addicted. If caffeine use for these people is stopped they may have withdrawals symptoms of feeling tired and headaches.
Effects
Physical
Caffeine acts on both the respiratory system and cardiovascular system. The cardiovascular system is the pathway the human body uses for circulating blood, supplying oxygen and removing waste products. The respiratory system is the system involved with the exchange of oxygen and carbon dioxide between the atmosphere and the blood.
Via many of these physiological responses, the fatigue an athlete would normally feel is postponed, allowing physical activity to be sustained for longer and of a higher level.
Cognitive
As caffeine targets the brain, there are many cognitive effects from using it. Caffeine can reduce tiredness and improve reaction time.
Disadvantages
Physical
Caffeine is a mild diuretic, which can often lead to dehydration. Other physical disadvantages include, impaired fine motor control, observed via the shakiness of athlete's hands, gastrointestinal upset, increased heart rate and sleep disruptions.
Cognitive
Caffeine can cause feelings of anxiety and insomnia. Studies have found that sleep deprivation has a significant effect on sub-maximal, prolonged exercise. Caffeine also elevates stress hormone levels and one's perception of stress.
Effectiveness
Studies have found that typical doses of caffeine from 1–3 mg per kg of body weight will provide an effective improvement to performance. Previously, high doses were used such as 6 mg/kg, until recently lower doses supply the desired benefits with less consequences.
There is preliminary evidence that shows caffeine is effective for endurance and anaerobic activities.
Anaerobic athletes
In studies of trained males the discovery of the optimal amount of caffeine for anaerobic exercise was determined. A caffeine dosage of 3–5 mg/kg may improve high-intensity sprint performance when consumed prior to exercise.
One analysis showed that there were small improvements, in which they discussed for these activities correlate to meaningful differences in performance. The following conclusions were drawn:
Caffeine ingested resulted in an increase in upper body strength but not lower body strength.
For strength exercises, there was no significant differences between trained and untrained subjects
Caffeine in capsule form had a greater influence on performance rather than liquid form, gums and gels were not tested.
Using a vertical jump as an indicator of muscle power, results showed a significant increase in power, supporting caffeine as a possible ergogenic aid.
References
Exercise biochemistry
Sports culture
Doping in sport | Caffeine use for sport | [
"Chemistry",
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60,757,701 | https://en.wikipedia.org/wiki/Collagen%20loss | Collagen loss is the gradual decrease of levels of collagen in the body. Collagen is the main structural protein found in the body's various connective tissues (skin, bones, tendons, etc.) where it contributes to much of their strength and elasticity.
Collagen loss occurs naturally as a part of aging, but can also be influenced by environmental factors such as exposure to ultraviolet light, tobacco, and excessive intake of sugar. Collagen loss is highly visible in the skin where it can cause the skin to lose elasticity, reduction of the thickness of the epidermis, an increase in the formation of wrinkles and sagging and also make the skin vulnerable and easily damaged.
Prevalent throughout the body, loss of collagen can also contribute to numerous other disorders such as
joint pain, weakened hair and nails, reduced bone density, gastrointestinal issues, and reduced muscle mass. Numerous interventions exist to address the loss of collagen with varying levels of efficacy and evidentiary support.
Collagen
Collagen is the main structural protein in the extracellular matrix found in the body's various connective tissues.
It is a rigid, non-soluble, fibrous protein that adds up to one-third of the proteins in the human body.
Collagen is mostly made up of molecules packed together to form long and thin fibrils that support each other and ensure the skin is strong and elastic. Various types of collagens have individual roles and structures. Most collagen belongs to types 1, 2, and 3. Collagen consists mainly of amino acids and can be mostly found in tendons, muscles, bones, skin, ligaments, and other fibrous tissues. It helps keep the skin strong and supple and sustains the renewal of skin cells and the replacement of damaged and dead body cells. Collagen tissues provide support for the formation of bones, tendons, and cartilage, which depends on their level of mineralization.
Molecular mechanisms in skin aging
Many dissimilar models have been used to explain skin aging on a molecular basis, such as the theory of cellular senescence, the reduction of the cells' DNA repair capacity, the loss of telomeres, oxidative stress, etc. It is believed that external factors cause a large portion of skin aging, while only 3% is caused by hereditary genetic influences. The following sections discuss prominent models and advancements in molecular mechanism studies related to skin aging.
Oxidative stress
Oxidative stress results from the lack of balance between the systemic production of reactive oxygen species (ROS) and the biological system's capacity to detoxify them or repair the resulting damage. It is known that reactive oxygen species take part in dermal changes taking place outside the cells in both aging caused by internal factors and those caused by external factors. ROS can be created within many dissimilar sources, which include the mitochondria, endoplasmic reticulum and peroxisomes. In normal conditions the binding of ligands to receptor tyrosine kinases (RTKs) activates them, while the various actions of RTKs on the cells' surface are repressed by receptor protein tyrosine phosphatases.
DNA damage
Exposure to ultraviolet rays damages DNA, which may disrupt the function of the genes that play a role in the skin stem cells' homeostasis.
Mutations in DNA from frequent exposure to UV radiation may result in aging prematurely or carcinogenesis. When DNA absorbs photons in the UV-B range the nucleotide arrangement structurally changes which leads to the DNA strands having defects. In the lesser species, they can repair the damage to the DNA using the photolyase enzyme, but higher species do not have this enzyme. In human cells, repair can be achieved through the nucleotide excision repair pathway; when the associated proteins are deficient, the skin becomes susceptible to premature aging.
Telomere shortening
Telomeres are nucleoid sequences that repeat themselves and cap chromosomes. They protect chromosomes from dilapidation and recombination abnormalities. Their length decreases with every division of the cell and results in cellular senescence. They are critical structures at the end of the eukaryotic chromosomes, consisting of many copies of G rich repeats. Without telomeres, chromosomes will combine and cause instability in the genes. The enzyme that increases telomere length to prevent them from becoming short is called telomerase. Deficiency of this enzyme can hasten telomere shortening which can cause a flawed regeneration of the tissue. This also suppresses the production of epidermal cells. Also, exposure to UV radiation causes mutations to telomeres and sufficient exposure can result in the deaths of cells.
"Inflammaging"
"Inflammaging" refers a chronic, sterile, low-grade inflammation that develops with advanced age. It affects the start and progression of diseases that occur due to aging, e.g. type 2 diabetes. It occurs in the skin because when exposed to UV radiation, it damages the epidermal cells, which in turn causes inflammation to occur.
Increase in age
When an individual ages, the outermost layer of skin becomes thin despite the number of cell layers remaining unchanged. The number of cells that contain pigment decreases, and the melanocytes that remain increase in size. This is why aging skin looks thin, pale, and translucent. Large spots may be pigmented when some areas are exposed to sunlight. The various alterations in the skin and underlying connective tissue may decrease its strength and elasticity. Also, the blood vessels in the outer skin become more delicate and can result in bruises and bleeding under the skin's surface. The subcutaneous glands also excrete decreased amounts of oil as you age. Men experience this shortage mostly after reaching the age of 80 years. Women may slowly begin excreting less oil after menopause, making it difficult to keep the skin moist. The subcutaneous fat layer also decreases, reducing the insulation and padding capability of the skin. This can put the individual at risk of an injury and makes maintaining body temperature difficult. The sweat glands also reduce the amount of sweat they produce, making the individual's body harder to cool.
Lifestyle habits
Excessive sugar intake
Too much sugar intake can negatively impact the body, including damage to collagen. Excess sugar consumption results in glycation that produces AGEs. This occurs naturally, and when too much sugar is consumed, the AGE molecules stick to the collagen molecules turning them stiff, thus damaging them. The process of glycation does not only damage the collagen existing in the body but also makes some alterations to its stability. When an individual consumes excessive amounts of sugar, the glycation process converts collagen into an unstable type 1, which becomes more vulnerable and can be easily broken down, potentially leading to premature aging.
Tobacco usage
The use of tobacco can cause damage to the skin's collagen layer. It can cause the skin around the lips to lose collagen when in contact with the smoke or due to puckering of the lips around the cigarette. It may also cause blood vessels to constrict and reduce blood flow. Due to this, perioral collagen (connective tissue around the mouth below the skin) may show signs of damage. When collagen is lost in large amounts, it may cause wrinkles to emerge. Tobacco use can also result in slow collagen healing.
Treatment for collagen loss
There are various ways in which an individual can treat the loss of collagen. Dietary changes may increase the turnover of cells and increase the creation of collagen. One can also adopt exercises that stimulate the production of collagen and also increase their intake of vitamin D. Moreover, applying an adequate amount of sunscreen can prevent UV rays from the sun from causing damage to your skin. You can also protect yourself from some of the causatives that break down collagen. Avoid spending too much time in the sun, apply sunblock, avoid smoking tobacco, drink plenty of water to prevent dehydration, and participate in stress-relieving activities. Stress is known to cause skin aging.
Various other interventions can aid in preserving healthy, youthful skin. Taking vitamins C and A can provide a boost to collagen production in the body. To maintain healthy skin, individuals can nurture and protect the collagen present in their bodies by consuming nutritious foods rich in the necessary vitamins, minerals, and amino acids. This promotes collagen production and reduces cellular damage within the body.
References
Aging-associated diseases | Collagen loss | [
"Biology"
] | 1,785 | [
"Senescence",
"Aging-associated diseases"
] |
60,758,292 | https://en.wikipedia.org/wiki/Wound%20response%20in%20plants | Plants are constantly exposed to different stresses that result in wounding. Plants have adapted to defend themselves against wounding events, like herbivore attacks or environmental stresses. There are many defense mechanisms that plants rely on to help fight off pathogens and subsequent infections. Wounding responses can be local, like the deposition of callose, and others are systemic, which involve a variety of hormones like jasmonic acid and abscisic acid.
Overview
There are many forms of defense that plants use to respond to wounding events. There are physical defense mechanisms that some plants utilize, through structural components, like lignin and the cuticle. The structure of a plant cell wall is incredibly important for wound responses, as both protect the plant from pathogenic infections by preventing various molecules from entering the cell.
Plants are capable of activating innate immunity, by responding to wounding events with damage-associated Molecular Patterns (DAMPs). Additionally, plants rely on microbe-associated molecular patterns (MAMPs) to defend themselves upon sensing a wounding event. There are examples of both rapid and delayed wound responses, depending on where the damage took place.
MAMPs/ DAMPS & Signaling Pathways
Plants have pattern recognition receptors (PRRs) that recognize MAMPs, or microbe-associated molecular patterns. Upon entry of a pathogen, plants are vulnerable to infection and lose a fair amount of nutrients to said pathogen. The constitutive defenses are the physical barriers of the plant; including the cuticle or even the metabolites that act toxic and deter herbivores. Plants maintain an ability to sense when they have an injured area and induce a defensive response. Within wounded tissues, endogenous molecules become released and become Damage Associated Molecular Patterns (DAMPs), inducing a defensive response. DAMPs are typically caused by insects that feed off the plant. Such responses to wounds are found at the site of the wound and also systemically. These are mediated by hormones.[1]
As a plant senses a wound, it immediately sends a signal for innate immunity. These signals are controlled by hormones such as jasmonic acid, ethylene and abscisic acid. Jasmonic acid induces the prosystemin gene along with other defense related genes such as abscisic acid, and ethylene, contributing to a rapid induction of defense responses. Other physical factors also play a vital role in wound signaling, which include hydraulic pressure and electrical pulses. Most of these that are involved within wound signaling also function in signaling other defense responses. Cross-talk events regulate the activation of different roles.
Callose, Damaged Sieve Tube Elements, and P-Proteins
Sieve elements are very rich in sugars and various organic molecules. Plants don't want to lose these sugars when the sieve elements get damaged, as the molecules are a very large energy investment. The plants have both short-term and long-term mechanisms to prevent sieve element sap loss. The short-term mechanism involves sap proteins, and the long-term mechanism involves callose, which helps to close the open channels in broken sieve plates.
The main mechanism for closing damaged sieve elements involves P-proteins, which act as a plug in the sieve element pores. P-proteins essentially plug the pores that form in sieve elements. They act as a stopper in the damaged sieve elements by blocking the open channels so that no additional sap or sugar can be lost.
A longer-term solution to wounded sieve tube elements involves the production of callose at the sieve pores. Callose is a β-1,3 glucan synthesized by callose synthase, which is an enzyme that's localized within the plasma membrane. Callose gets synthesized after the sieve tube elements undergo damage and/or stress. The use of wound callose occurs when callose gets deposited following sieve element damage. Wound callose is proven to first be deposited at the sieve plate pores, or the intracellular connections, where it then spreads to different regions. Essentially, wound callose seals off the parts that were damaged, and separates them from the parts that are still healthy and not broken. Once the sieve elements get fixed, the callose is always dissipated by callose-hydrolyzing enzyme. Callose is also synthesized during normal plant growth and development, and it typically responds to things like high temperatures, or allows the plant to prepare for more dormant seasons.
When the sieve elements get damaged, the sap, sugar, and other molecules inside rush to the end that was damaged. If there was no mechanism to stop the sugars from leaking out the plant would lose an incredibly large amount of invested energy.
Jasmonic Acid
Jasmonic acid (JA) is a plant hormone that increases in concentration in response to insect herbivore damage. The rise in JA induces the production of proteins functioning in plant defenses. JA also induces the transcription of multiple genes coding for key enzymes of the major pathways for secondary metabolites. Its structure and synthesis show parallels to oxylipins, which function in inflammatory responses. JA is synthesized by the octadecanoid pathway, which is activated in response to wound-induced signals. It is a derivative of the most rich fatty acid in the lipids of leaf membranes, alpha-linolenic acid. When plants experience mechanical wounding or herbivory, JA is synthesized de novo and induces genome-wide changes in gene expression. JA travels through plants via the phloem, and accumulates in vascular tissue. JA acts as an intracellular signal in order to promote responses in distal tissues. The perception of jasmonate in distal responding leaves is necessary for recognition of the transmissible signal that coordinates responses to wounding stress. JA mutants, which lack the gene encoding jasmonic acid, are killed by insect herbivore damage that would otherwise not harm normal-type plants. Upon the application of JA to the same mutants, resistance is restored. Signaling agents such as ethylene, methyl salicylate, and salicylic acid can pair with JA and enhance JA responses.
Protections Against Abiotic Stress
Morphological Changes
Plants can protect themselves from abiotic stress in many different ways, and most include a physical change in the plant’s morphology. Phenotypic plasticity is a plant’s ability to alter and adapt its morphology in response to the external environments to protect themselves against stress. One way that plants alter their morphology is by reducing the area of their leaves. Though large and flat leaves are favorable for photosynthesis because there is a larger surface area for the leaf to absorb sunlight, bigger leaves are more vulnerable to environmental stresses. For example, it is easier for water to evaporate off of large surface areas which can rapidly deplete the soil of its water and cause drought stress. Plants will reduce leaf cell division and expansion and alter the shape to reduce leaf area.
Another way that plants alter their morphology to protect against stress is by changing the leaf orientation. Plants can suffer from heat stress if the sun’s rays are too strong. Changing the orientation of their leaves in different directions (parallel or perpendicular) allows plants to reduce damage from intense light. Leaves also wilt in response to stress, because it changes the angle at which the sun hits the leaf. Leaf rolling also minimizes how much of the leaf area is exposed to the sun.
Constitutive structures
Trichomes are small, hair-like growths on plant leaves and stems which help the plant protect itself. Although not all trichomes are alive (some undergo apoptosis, but their cell walls are still present) they protect the leaf by keeping its surface cool and reducing evaporation. In order for trichomes to successfully protect the plant, they must be dense. Oftentimes, trichomes will appear white on a plant, meaning that they are densely packed and are able to reflect a large amount of light off of the plant to prevent heat and light stress. Although trichomes are used for protection, they can be disadvantageous for plants at times because trichomes may reflect light away from the plant that can be used to photosynthesize.
The cuticle is a layered structure of waxes and hydrocarbons located on the outer layer of the epidermis which also helps protect the plant from stress. Cuticles can also reflect light, like trichomes, which reduces light intensity and heat. Plant cuticles can also limit the diffusion of water and gases from the leaves which helps maintain them under stress conditions. Thicker cuticles have been found to decrease evaporation, so some plants will increase the thickness of their cuticles in response to drought stress.
Symbiotic Relationships
Plants are also further protected from both abiotic and biotic stresses when plant growth promoting Rhizobacteria (PGPRs) are present. Rhizobacteria are root-colonizing and non-pathogenic, and they form symbiotic relationships with plants that can elicit stress responsive pathways. PGPRs also improve key physiological processes in plants such as water and nutrient uptake, photosynthesis, and source-sink relationships. Bacteria will respond to substances secreted by plant roots and optimize nutrient acquisition for the plant with their own metabolic processes. Though dependent on the strain, most Rhizobacteria will produce major phytohormones such as auxins, gibberellins, cytokinins, abscisic acid (ABA) and ethylene, which stimulate plant growth and increase the plant’s resistance to pathogens. Other substances are also released by Rhizobacteria, including nitric oxide, enzymes, organic acids, and osmolytes.
See also
Embryo rescue
Somatic embryogenesis
Wound healing
Jasmonic acid
Herbivore
Trichome
Cuticle
Pathogen
References
Plant physiology
Plant cells
Eukaryotic cells | Wound response in plants | [
"Biology"
] | 2,019 | [
"Plant physiology",
"Plants"
] |
60,758,751 | https://en.wikipedia.org/wiki/Artemis%20program | The Artemis program is a Moon exploration program led by the United States' National Aeronautics and Space Administration (NASA), formally established in 2017 via Space Policy Directive 1. It is intended to reestablish a human presence on the Moon for the first time since the Apollo 17 mission in 1972. The program's stated long-term goal is to establish a permanent base on the Moon to facilitate human missions to Mars.
Two principal elements of the Artemis program are derived from the now-cancelled Constellation program: the Orion spacecraft and the Space Launch System (SLS) (as a reincarnation of Ares V). Other elements of the program, such as the Lunar Gateway space station and the Human Landing System, are in development by government space agencies and private spaceflight companies, collaborations bound by the Artemis Accords and governmental contracts.
The Space Launch System, Orion spacecraft and the Human Landing System form the main spaceflight infrastructure for Artemis, and the Lunar Gateway plays a supporting role in human habitation. Supporting infrastructures for Artemis include the Commercial Lunar Payload Services, development of ground infrastructures, Artemis Base Camp on the Moon, Moon rovers, and spacesuits. Some aspects of the program have been criticized, such as the use of a near-rectilinear halo orbit and the program's sustainability.
Orion's first launch on the Space Launch System was originally set in 2016, but faced numerous delays; it launched on November 16, 2022 as the Artemis I mission, with robots and mannequins aboard. , the crewed Artemis II launch is expected to take place in April 2026, the Artemis III crewed lunar landing is scheduled for mid-2027, the Artemis IV docking with the Lunar Gateway is planned for late 2028, the Artemis V docking with the European Space Agency's ESPRIT, Canada's Canadarm3, and NASA's Lunar Terrain Vehicle is planned for early 2030, and the Artemis VI docking which is expected to integrate the Crew and Science Airlock with the Lunar Gateway station is planned for early 2031. After Artemis VI, NASA plans yearly landings on the Moon from then on. However, the NASA Inspector General has called the schedules unrealistic.
Overview
The Artemis program is organized around a series of SLS missions. These space missions will increase in complexity and are scheduled to occur at intervals of a year or more. NASA and its partners have planned Artemis I through Artemis V missions; later Artemis missions have also been proposed. Each SLS mission centers on the launch of an SLS launch vehicle carrying an Orion spacecraft. Missions after Artemis II will depend on support missions launched by other organizations and spacecraft for support functions.
SLS missions
Artemis I (2022) was the successful uncrewed test of the SLS and Orion, and was the first test flight for both craft. The Artemis I mission placed Orion into a lunar orbit and then returned to Earth. The SLS Block 1 design uses the Interim Cryogenic Propulsion Stage (ICPS) second stage, which performs the trans-lunar injection burn to send Orion to lunar space. For Artemis I, Orion braked into a polar distant retrograde lunar orbit and remained for about six days before boosting back toward Earth. The Orion capsule separated from its service module, re-entered the atmosphere for aerobraking, and splashed down in the Pacific Ocean under parachutes.
Artemis II (2026) is planned to be the first crewed test flight of SLS and the Orion spacecraft. The four crew members will perform extensive testing in Earth orbit, and Orion will then be boosted into a free-return trajectory around the Moon, which will return Orion to Earth for re-entry and splashdown. Launch is scheduled for no earlier than April 2026.
Artemis III (2027) is planned to be the first American crewed lunar landing since Apollo 17 in December 1972. The mission depends on a support mission to place a Starship Human Landing System (HLS) in a near-rectilinear halo orbit (NRHO) of the Moon prior to the launch of SLS/Orion. After Starship HLS reaches NRHO, SLS/Orion will send the Orion spacecraft with a crew of four to dock with HLS. Two astronauts will transfer to HLS, which will descend to the lunar surface and spend about 6.5 days on the surface. The astronauts will perform at least two Extravehicular Activities (EVAs) on the surface before the HLS ascends to return them to a rendezvous with Orion. Orion will return the four astronauts to Earth. Launch is scheduled for no earlier than mid-2027.
Artemis IV (2028) is planned to be the second crewed lunar landing mission. Orion and an upgraded Starship HLS will dock with the Lunar Gateway station in NRHO prior to the landing. A prior support mission will deliver the first two Lunar Gateway modules to NRHO. The extra power of this mission's SLS Block 1B will allow it to deliver the I-HAB Gateway module for connection to the Lunar Gateway. Launch is scheduled for no earlier than September 2028.
Artemis V (2030) is planned to be the third crewed lunar landing, which will deliver four astronauts to the Lunar Gateway station. The mission will deliver the European Space Agency's ESPRIT refueling and communications module and Canadarm3, a Canadian-built robotic arm system for the Gateway. Also delivered will be NASA's Lunar Terrain Vehicle. Launch is scheduled for no earlier than March 2030. The mission will also be the first to use Blue Origin's Blue Moon lander to take astronauts to the Moon's surface.
Artemis VI (2031) is planned to be the fourth crewed lunar landing, which will integrate the Crew and Science Airlock with the Gateway space station. Launch is scheduled for no earlier than March 2031. As of 2024, the Airlock module is under construction.
Support missions
Support missions include robotic landers, delivery of Gateway modules, Gateway logistics, delivery of the HLS, and delivery of elements of the Moon base. Most of these missions are executed under NASA contracts to commercial providers.
Under the Commercial Lunar Payload Services (CLPS) program, several robotic landers will deliver scientific instruments and robotic rovers to the lunar surface after Artemis I. Additional CLPS missions are planned throughout the Artemis program to deliver payloads to the Moon base. These include habitat modules and rovers in support of crewed missions.
A Human Landing System (HLS) is a spacecraft that can convey crew members from NRHO to the lunar surface, support them on the surface, and return them to NRHO. Each crewed landing needs one HLS, although some or all of the spacecraft may be reusable. Each HLS must be launched from Earth and delivered to NRHO in one or more launches. The initial commercial contract was awarded to SpaceX for two Starship HLS missions, one uncrewed and one crewed as part of Artemis III. These two missions each require one HLS launch and multiple fueling launches, all on SpaceX Starship launchers. NASA later exercised an option under the initial contract to commission an upgraded Starship HLS for Artemis IV and a separate contract to Blue Origin to develop a third crewed lunar lander, which will make its first crewed flight as part of the Artemis V mission.
The first two Gateway modules (PPE and HALO) will be delivered to NRHO in a single launch using a Falcon Heavy launcher. Originally planned to be available prior to Artemis III, as of 2021 it is planned for availability before Artemis IV.
The Gateway will be resupplied and supported by launches of Dragon XL spacecraft launched by Falcon Heavy. Each Dragon XL will remain attached to Gateway for up to six months. The Dragon XLs will not return to Earth, but will be disposed of, probably by deliberate crashes on the lunar surface.
History
Early history
The Artemis program incorporates several major components of previously cancelled NASA programs and missions, including the Constellation program and the Asteroid Redirect Mission. Originally legislated by the NASA Authorization Act of 2005, Constellation included the development of Ares I, Ares V, and the Orion Crew Exploration Vehicle. The program ran from the early 2000s until 2010.
In May 2009, U.S. President Barack Obama established the Augustine Committee to take into account several objectives including support for the International Space Station, development of missions beyond low Earth orbit (including the Moon, Mars, and near-Earth objects), and use of the commercial space industry within defined budget limits. The committee concluded that the Constellation program was massively underfunded and that a 2020 Moon landing was impossible. Constellation was subsequently put on hold.
On April 15, 2010, President Obama spoke at the Kennedy Space Center, announcing the administration's plans for NASA and cancelling the non-Orion elements of Constellation on the premise that the program had become nonviable. He instead proposed US$6 billion in additional funding and called for development of a new heavy-lift rocket program to be ready for construction by 2015 with crewed missions to Mars orbit by the mid-2030s.
On October 11, 2010, President Obama signed into law the NASA Authorization Act of 2010, which included requirements for the immediate development of the Space Launch System as a follow-on launch vehicle to the Space Shuttle, and continued development of a Crew Exploration Vehicle to be capable of supporting missions beyond low Earth orbit starting in 2016, while making use of the workforce, assets, and capabilities of the Space Shuttle program, Constellation program, and other NASA programs. The law also invested in space technologies and robotics capabilities tied to the overall space exploration framework, ensured continued support for Commercial Orbital Transportation Services, Commercial Resupply Services, and expanded the Commercial Crew Development program.
On June 30, 2017, President Donald Trump signed an executive order to re-establish the National Space Council, chaired by Vice-President Mike Pence. The Trump administration's first budget request kept Obama-era human spaceflight programs in place: Commercial Resupply Services, Commercial Crew Development, the Space Launch System, and the Orion spacecraft for deep space missions, while reducing Earth science research and calling for the elimination of NASA's education office.
Redefinition and naming as Artemis
On December 11, 2017, president Trump signed Space Policy Directive 1, a change in national space policy that provides for a U.S.-led, integrated program with private sector partners for a human return to the Moon, followed by missions to Mars and beyond. The policy calls for the NASA administrator to "lead an innovative and sustainable program of exploration with commercial and international partners to enable human expansion across the Solar System and to bring back to Earth new knowledge and opportunities". The effort intends to more effectively organize government, private industry, and international efforts toward returning humans to the Moon and laying the foundation of eventual human exploration of Mars.
Space Policy Directive 1 authorized the lunar-focused campaign. The campaign, later named Artemis, draws upon legacy US spacecraft programs, including the Orion space capsule, the Lunar Gateway space station, and Commercial Lunar Payload Services, and creates entirely new programs such as the Human Landing System. The in-development Space Launch System is expected to serve as the primary launch vehicle for Orion, while commercial launch vehicles will launch various other elements of the program.
On March 26, 2019, Vice President Mike Pence announced that NASA's Moon landing goal would be accelerated by four years with a planned landing in 2024. On May 16, 2019, NASA Administrator Jim Bridenstine announced that the new program would be named Artemis, after the goddess of the Moon in Greek mythology who is the twin sister of Apollo. Despite the immediate new goals, Mars missions by the 2030s were still intended .
In mid-2019, NASA requested US$1.6 billion in additional funding for Artemis for fiscal year 2020, while the Senate Appropriations Committee requested from NASA a five-year budget profile which is needed for evaluation and approval by Congress.
In February 2020, the White House requested a funding increase of 12% to cover the Artemis program as part of its fiscal year 2021 budget. The total budget would have been US$25.2 billion per year with US$3.7 billion dedicated toward a Human Landing System. NASA Chief Financial Officer Jeff DeWit said he thought the agency has "a very good shot" to get this budget through Congress despite Democratic concerns around the program. However, in July 2020 the House Appropriations Committee rejected the White House's requested funding increase. The bill proposed in the House dedicated only US$700 million toward the Human Landing System, 81% (US$3 billion) short of the requested amount.
In April 2020, NASA awarded funding to Blue Origin, Dynetics, and SpaceX for 10-month-long preliminary design studies for the HLS.
Throughout February 2021, Acting Administrator of NASA Steve Jurczyk reiterated those budget concerns when asked about the project's schedule, clarifying that "The 2024 lunar landing goal may no longer be a realistic target [...]".
On February 4, 2021, the Biden administration endorsed the Artemis program. More specifically, White House Press Secretary Jen Psaki expressed the Biden administration's "support [for] this effort and endeavor".
On April 16, 2021, NASA contracted SpaceX to develop, manufacture, and fly two lunar landing flights with the Starship HLS lunar lander. Blue Origin and Dynetics protested the award to the Government Accountability Office (GAO) on April 26. After the GAO rejected the protests, Blue Origin sued NASA over the award, and NASA agreed to stop work on the contract until November 1, 2021 as the lawsuit proceeded. The judge dismissed the suit on 4 November 2021 and NASA resumed work with SpaceX.
On September 25, 2021, NASA released its first digital, interactive graphic novel in celebration of National Comic Book Day. "First Woman: NASA's Promise for Humanity" is the fictional story of Callie Rodriguez, the first woman to explore the Moon.
On November 15, 2021, an audit of NASA's Office of Inspector General estimated the true cost of the Artemis program at about $93 billion until 2025.
In addition to the initial SpaceX contract, NASA awarded two rounds of separate contracts in May 2019 and September 2021, on aspects of the HLS to encourage alternative designs, separately from the initial HLS development effort. It announced in March 2022 that it was developing new sustainability rules and pursuing both a Starship HLS upgrade (an option under the initial SpaceX contract) and new competing alternative designs. These came after criticism from members of Congress over lack of redundancy and competition, and led NASA to ask for additional support.
Artemis I (2022)
Artemis I was originally scheduled for late 2016, and as delays accrued, eventually for late 2021, but the launch date was then pushed back to August 29, 2022. Various delays related to final infrastructure repairs and weather pushed the launch date further out.
In October 2022, NASA launch managers decided on a new launch date in November, which were again slightly delayed due to preparation and weather. On November 16 at 01:47:44 EST (06:47:44 UTC), Artemis I successfully launched from the Kennedy Space Center.
Artemis I was completed at 09:40 PST (17:40 UTC) on 11 December, when the Orion spacecraft splashed down in the Pacific Ocean, west of Baja California, after a record-breaking mission, which saw Artemis travel more than on a path around the Moon before returning safely to Earth. The splashdown occurred 50 years to the day since NASA's Apollo 17 Moon landing, the last human crewed mission to touch down on the lunar surface.
Artemis II (2026)
Artemis II is scheduled to launch in April 2026 as a crewed lunar flyby. The European Service Module for the mission was completed and handed over to NASA in 2023. Testing is underway on the Orion module for Artemis II. In April 2024, Lockheed was on track to hand over the Orion module by September after testing was complete. A NASA OIG report released on May 1 reported the mission was still on track, provided corrective actions on the Orion heat shield were made. The Artemis II crew planned to conduct a series of trainings and simulations prior to launch, the first of which occurred in May 2024.
The SLS core stage for the mission was delivered to Kennedy Space Center (KSC) in July 2024. Notably, the SLS core stage for Artemis II was the last to be fully built at the Michoud Assembly Facility: future missions starting with Artemis III will have the core stage partly built after arriving at Kennedy Space Center (KSC) in Florida, managed by Exploration Ground Systems, which was deemed to be more efficient by program officials. In July, the Orion spacecraft was moved from the testing cell to the altitude chamber inside the Neil Armstrong Operations and Checkout Building at KSC. Rocket stacking operations began on November 20, 2024, when the left aft assembly of the booster was stacked onto the Mobile Launcher. The stacking marked a crucial step for launch in late 2025.
On December 5, 2024, NASA delayed the Artemis II mission from September 2025 to April 2026, citing damage found to the heat shield of the uncrewed Orion capsule that flew on the Artemis I mission in 2022.
Crew
Artemis II is to be crewed by four astronauts: Commander Reid Wiseman, Pilot Victor J. Glover, Payload Specialist Christina Koch, and Mission Specialist Jeremy Hansen. Jenni Sidey-Gibbons is Hansen's backup; she will join the mission if Hansen is unable to.
Glover, Koch, and Hansen are planned to be the first person of color, woman, and non-US citizen to go beyond low Earth orbit, respectively. Hansen and Sidey-Gibbons are Canadian and have been assigned by the Canadian Space Agency; a 2020 treaty between the United States and Canada led to their involvement.
Artemis III (2027)
Artemis III is expected to launch in mid-2027 as the first crewed landing on the Moon since Apollo 17. In February 2024, NASA completed full qualification testing of the docking systems on Starship HLS. Also in February, the bulk of the manufacturing for the core stage of the SLS to be used in the mission was completed. In April 2024, NASA announced the successful completion of Starship’s first internal propellant transfer demonstration. The Starship’s tanker variant ability to act as an orbital propellant depot to Starship HLS is a key capability necessary to complete the Artemis III mission. A ship-to-ship propellant transfer demonstration to further prove out the capability is expected in 2025. The European Service Module for the mission was reported on track to be handed over to NASA in summer 2024. The first integrated test for the mission, which included the next generation space suits developed by Axiom Space, and the airlock module of Starship HLS was conducted in June 2024.
On December 5, 2024, NASA delayed the Artemis III mission from September 2026 to mid-2027, citing damage found to the heat shield of the uncrewed Orion capsule that flew on the Artemis I mission in 2022.
Instruments and payloads
In March 2024, NASA announced the scientific instruments to be included on the mission were a compact, autonomous seismometer suite called the Lunar Environment Monitoring Station, or LEMS. LEMS will characterize the regional structure of the Moon's crust and mantle to inform the development of lunar formation and evolution models. Another instrument is Lunar Effects on Agricultural Flora, a.k.a. LEAF, which will investigate the impact of the lunar surface environment on space crops. The third instrument is the Lunar Dielectric Analyzer, or LDA, an internationally contributed payload that will measure the regolith's ability to propagate an electric field.
Artemis IV (2028)
Artemis IV is expected to launch in September 2028. Prior to the launch of the mission, a Falcon Heavy is planned to launch the first two Lunar Gateway elements: the Power and Propulsion Element and Habitation and Logistics Outpost, now scheduled for 2027. Artemis IV will then be responsible for launching with a crew with the International Habitation Module (I-Hab) and adding the module to the Gateway space station. SLS Block 1B manufacture began in March 2024. The I-Hab module construction was underway as of April 2024. In May 2024, it was reported NASA made significant progress towards completion of Mobile Launcher 2 (ML-2), the launch platform that will be used by the larger SLS Block 1B. However, in August 2024, the NASA Inspector General estimated that the launch platform could end up costing the agency $2.5 billion, more than six times its original value and may not be ready to support a launch until 2029, making the current launch schedule unrealistic.
NASA has highlighted five key points for the mission (in chronological order):
The crewed Orion spacecraft and Lunar I-Hab Gateway element will launch as a co-manifested payload on an SLS Block 1B rocket to lunar orbit.
Orion will deliver Lunar I-Hab to Gateway, where it will dock to HALO.
A Human Landing System spacecraft will dock to Gateway.
Artemis IV crew members will use the Human Landing System to descend to and later ascend from the lunar surface.
Artemis IV crew will return to Earth on Orion.
Artemis V (2030)
Artemis V is expected to launch in March 2030. The mission will launch four astronauts on a Space Launch System rocket and an Orion spacecraft to the Lunar Gateway and will be the third lunar landing of the Artemis program. In addition, Artemis V will deliver two new elements to the Gateway space station. After docking to the Gateway, two astronauts will board the Blue Moon lunar lander and fly it to the Lunar south pole to land near the Lunar Terrain Vehicle (LTV). This will be the first lunar landing since Apollo 17 to use an unpressurized lunar rover.
NASA has highlighted five key points for the mission (in chronological order):
The crewed Orion spacecraft and the Lunar View element will launch as a co-manifested payload on an SLS Block 1B rocket to lunar orbit.
Orion will deliver Lunar View to Gateway, where it will dock to HALO.
A Human Landing System spacecraft will dock to Gateway.
Artemis V crew members will use the Human Landing System to descend to and later ascend from the lunar surface.
Artemis V crew will return to Earth on Orion.
Artemis VI (2031)
Artemis VI is expected to launch in March 2031. According to NASA, the primary objectives of this mission would be to integrate the Crew and Science Airlock Module with Gateway and complete the fourth crewed lunar surface expedition of the Artemis missions. As of 2024, the Airlock module is under construction by Mohammed bin Rashid Space Centre.
NASA has highlighted five key points for the mission (in chronological order):
The crewed Orion spacecraft and Gateway’s Crew and Science Airlock will launch as a co-manifested payload on an SLS Block 1B rocket to lunar orbit.
Orion will deliver the Crew and Science Airlock to Gateway, where it will dock to Lunar I-Hab.
A Human Landing System spacecraft will dock to Gateway.
Artemis VI crew members will use the Human Landing System to descend to and later ascend from the lunar surface.
Artemis VI crew will return to Earth on Orion.
Supporting programs
Implementation of the Artemis program will require additional programs, projects, and commercial launchers to support the construction of the Lunar Gateway, launch resupply missions to the station, and deploy numerous robotic spacecraft and instruments to the lunar surface. Several precursor robotic missions are being coordinated through the Commercial Lunar Payload Services (CLPS) program, which is dedicated to scouting and characterization of lunar resources as well as testing principles for in-situ resource utilization (ISRU).
Commercial Lunar Payload Services
In March 2018, NASA established the Commercial Lunar Payload Services (CLPS) program with the aim of sending small robotic landers and rovers mostly to the lunar south pole region as a precursor to and in support of crewed missions. The main goals include scouting of lunar resources, ISRU feasibility testing, and lunar science. NASA is awarding commercial providers indefinite delivery/indefinite quantity contracts to develop and fly lunar landers with scientific payloads. The first phase considered proposals capable of delivering at least of payload by the end of 2021. Proposals for mid-sized landers capable of delivering between and of cargo were planned to also be considered for launch beyond 2021.
In November 2018, NASA announced the first nine companies that were qualified to bid on the CLPS transportation service contracts (see list below). On 31 May 2019, three of those were awarded lander contracts: Astrobotic Technology, Intuitive Machines, and OrbitBeyond. On July 29, 2019, NASA announced that it had granted OrbitBeyond's request to be released from obligations under the contract citing "internal corporate challenges".
The first twelve payloads and experiments from NASA centers were announced on February 21, 2019. On July 1, 2019, NASA announced the selection of twelve additional payloads, provided by universities and industry. Seven of these are scientific investigations while five are technology demonstrations.
The Lunar Surface Instrument and Technology Payloads (LSITP) program was soliciting payloads in 2019 that do not require significant additional development. They will include technology demonstrators to advance lunar science or the commercial development of the Moon.
In November 2019, NASA added five contractors to the group of companies who are eligible to bid to send large payloads to the surface of the Moon under the CLPS program: Blue Origin, Ceres Robotics, Sierra Nevada Corporation, SpaceX, and Tyvak Nano-Satellite Systems.
In April 2020, NASA selected Masten Space Systems for a follow-on CLPS delivery of cargo to the Moon in 2022. On June 23, 2021, Masten Space Systems announced it was delayed until November 2023. Dave Masten, the founder and chief technology officer, blamed the delay on the COVID pandemic and industry-wide supply chain issues.
In February 2021, NASA selected Firefly Aerospace for a CLPS launch to Mare Crisium in mid-2023.
International contractors
Artemis Accords
On May 5, 2020, Reuters reported that the Trump administration was drafting a new international agreement outlining the laws for mining on the Moon. NASA Administrator Jim Bridenstine officially announced the Artemis Accords on May 15, 2020. It consists of a series of multilateral agreements between the governments of participating nations in the Artemis program "grounded in the Outer Space Treaty of 1967". The Artemis Accords have been criticized by some American researchers as "a concerted, strategic effort to redirect international space cooperation in favor of short-term U.S. commercial interests".
Exploration Ground Systems (EGS)
The Exploration Ground Systems (EGS) Program is one of three NASA programs based at NASA's Kennedy Space Center in Florida. EGS was established to develop and operate the systems and facilities necessary to process and launch rockets and spacecraft during assembly, transport, and launch. EGS is preparing the infrastructure to support NASA's Space Launch System (SLS) rocket and its payloads, such as the Orion spacecraft for Artemis I.
Gateway Logistics Services
The Lunar Gateway is a space station to be constructed in lunar orbit, and the Gateway Logistics Services program will provide cargo and other supplies to the station, even when crews are not present. , only SpaceX's supply vehicle, known as Dragon XL, is planned to supply the Gateway. Dragon XL is a version of the Dragon spacecraft, to be launched by the Falcon Heavy. Unlike Dragon 2 and its predecessor, it is intended to be an expendable spacecraft.
Supporting Earth-launch vehicles
As of the early mission concepts outlined by NASA in May 2020 and refined by the HLS contract award in July 2021, the primary Earth-launch vehicles planned to support the Artemis program will include the NASA Space Launch System for the Orion vehicle, the Falcon Heavy for various components of the Lunar Gateway, and the Starship HLS configuration for the eventual delivery of the HLS vehicle. Other standard SpaceX Starships may be used later to meet other and yet to be determined crew and/or cargo handling mission needs. Additional launch vehicles will also be employed later for CLPS cargo services. The European Ariane 6 has been proposed to be part of the program in July 2019.
The Power and Propulsion Element (PPE) module and the Habitation and Logistics Outpost (HALO) of the Gateway, which were previously planned for the SLS Block 1B, will now fly together on a Falcon Heavy in 2027. The Gateway will be supported and resupplied by approximately 28 commercial cargo missions launched by undetermined commercial launch vehicles. The Gateway Logistics Services (GLS) will be in charge of resupply missions. GLS has also contracted for the construction of a resupply vehicle, Dragon XL, capable of remaining docked to the Gateway for one year of operations, providing and generating its own power while docked, and capable of autonomous disposal at the end of its mission.
In May 2019, the plan was for components of a crewed lunar lander to be deployed to the Gateway on commercial launchers before the arrival of the first crewed mission, Artemis III. An alternative approach where the HLS and Orion dock together directly was discussed.
As late as mid-2019, NASA considered use of Delta IV Heavy and Falcon Heavy to launch a crewed Orion mission given SLS delays. Given the complexity of conversion to a different vehicle, the agency ultimately decided to use only the SLS to launch astronauts.
LEO: Low Earth Orbit
TLI: Trans-Lunar Injection
Space Launch System
The Space Launch System (SLS) is a United States super heavy-lift expendable launch vehicle, which has been under development since its announcement in 2011. The SLS is the main Earth-launch vehicle of the Artemis lunar program, . NASA is required by the U.S. Congress to use SLS Block 1, which will be powerful enough to lift a payload of to low Earth orbit (LEO), and will launch Artemis I, II, and III. Starting in 2028, Block 1B is intended to debut the Exploration Upper Stage (EUS) and launch the notional Artemis IV–VII.
Starting in 2029, Block 2 is planned to replace the initial Shuttle-derived boosters with advanced boosters and would have a LEO capability of more than , again as required by Congress. Block 2 is intended to enable crewed launches to Mars. The SLS will launch the Orion spacecraft and use the ground operations capabilities and launch facilities at NASA's Kennedy Space Center in Florida.
In March 2019, the Trump administration released its Fiscal Year 2020 Budget Request for NASA. This budget did not initially include any money for the Block 1B and Block 2 variants of SLS, but later a request for a budget increase of $1.6 billion towards SLS, Orion, and crewed landers was made. Block 1B is now intended to debut on Artemis IV and will be used mainly for co-manifested crew transfers and logistics rather than constructing the Gateway as initially planned. An uncrewed Block 1B was planned to launch the Lunar Surface Asset in 2028, the first lunar outpost of the Artemis program, but now that launch has been moved to a commercial launcher. Block 2 development will most likely start in the late 2020s after NASA is regularly visiting the lunar surface and shifts focus towards Mars.
In October 2019, NASA authorized Boeing to purchase materials in bulk for more SLS rockets ahead of the announcement of a new contract. The contract was expected to support up to ten core stages and eight Exploration Upper Stages for the SLS 1B to transfer heavy payloads of up to 40 metric tons on a lunar trajectory.
SpaceX Starship
The SpaceX Starship system is a fully-reusable super heavy-lift Earth-launch system which is under development. It consists of a first-stage booster named Super-Heavy and a second-stage space vehicle which is generally named Starship and which will have several variants. A Starship HLS mission will use three variants: a tanker, a propellant depot, and the Starship HLS itself which will be designed only for lunar landings and takeoffs, and not for Earth landings. Some variants will be able to return to Earth for reuse.
The second-stage Starships are fully self-contained spacecraft, complete with their own propulsion systems. The combined Starship system using standard Starship variants for its second-stage is planned to launch crews and cargo, which may then be used to support the various developmental needs of the Artemis program, and also to support the needs of other NASA and SpaceX programs.
The SpaceX Starship is also qualified to be bid for Commercial Lunar Payload Services (CLPS) launches, and in 2021 was the winning NASA bid for a crewed lunar landing.
Falcon Heavy
The SpaceX Falcon Heavy is a partially reusable heavy-lift launcher. It will be used to launch the first two Gateway modules into NRHO. It will also be used to launch the Dragon XL spacecraft on supply missions to Gateway, and it is qualified to be bid for other launches under the CLPS program. It was selected under CLPS to launch the VIPER mission, though this mission was later cancelled in 2024 due to cost overruns and mission delays.
CLPS launchers
Under the CLPS (Commercial Lunar Payload Service) program, qualified CLPS vendors can use any launcher that meets their mission requirements.
Space vehicles
Orion
Orion is a class of partially reusable spacecraft to be used in the Artemis program. The spacecraft consists of a Crew Module (CM) space capsule designed by Lockheed Martin and the European Service Module (ESM) manufactured by Airbus Defence and Space. Capable of supporting a crew of six beyond low Earth orbit, Orion is equipped with solar panels, an automated docking system, and glass cockpit interfaces modeled after those used in the Boeing 787 Dreamliner. It has a single AJ10 engine for primary propulsion, and others including reaction control system engines. Although designed to be compatible with other launch vehicles, Orion is primarily intended to launch atop a Space Launch System (SLS) rocket, with a tower launch escape system.
Orion was originally conceived by Lockheed Martin as a proposal for the Crew Exploration Vehicle (CEV) to be used in NASA's Constellation program. Following the cancellation of the Constellation program in 2010, Orion was heavily redesigned for use in NASA's Journey to Mars initiative; later named Moon to Mars. The SLS replaced the Ares I as Orion's primary launch vehicle, and the service module was replaced with a design based on the European Space Agency's Automated Transfer Vehicle. A development version of Orion's CM was launched in 2014 during Exploration Flight Test-1, while at least four test articles were produced. By 2022, three flight-worthy Orion crew modules have been built, with an additional one ordered, for use in the Artemis program; the first of these was due to be launched on 30 November 2020, however Artemis I did not launch until 16 November 2022.
Dragon XL
Human Landing System (HLS)
The Human Landing System (HLS) is a critical component of the Artemis mission. This system transports crew from lunar orbit (the Gateway or an Orion spacecraft) to the lunar surface, acts as a lunar habitat, and then transports the crew back to lunar orbit. In 2021 SpaceX's Starship HLS program was awarded the winning NASA bid for the production of a crewed lunar landing vehicle. In May 2023, Blue Origin was selected as the second provider for lunar lander services.
Early developmental history of the HLS vehicle
Bidding for NASA's HLS lunar landing vehicle began in 2019. At that time, NASA elected to have the HLS designed and developed by commercial vendors. Eleven competing contracts were initially awarded in May 2019. In April 2020, NASA awarded three competing design contracts, and in April 2021, NASA selected the Starship HLS to proceed to development and production.
Separate from its early design and development program for its first HLS spacecraft, NASA retains multiple smaller contracts to study various elements of alternative HLS designs.
Starship HLS
The Starship Human Landing System (Starship HLS) was the winner selected by NASA for potential use for long-duration crewed lunar landings as part of NASA's Artemis program.
Starship HLS is a variant of SpaceX's Starship spacecraft optimized to operate on and around the Moon. In contrast to the Starship spacecraft from which it derives, Starship HLS will never re-enter an atmosphere, so it does not have a heat shield or flight control surfaces. In contrast to other proposed HLS designs that used multiple stages, the entire spacecraft will land on the Moon and will then launch from the Moon. Like other Starship variants, Starship HLS has Raptor engines mounted at the tail as its primary propulsion system. However, when it is within "tens of meters" of the lunar surface during descent and ascent, it will use high-thrust methane/oxygen RCS thrusters located mid-body instead of the Raptors to avoid raising dust via plume impingement. A solar array located on the nose below the docking port provides electrical power. Elon Musk stated that Starship HLS would be able to deliver "potentially up to 200 tons" to the lunar surface.
Starship HLS would be launched to Earth orbit using the SpaceX Super Heavy booster, and would use a series of tanker spacecraft to refuel the Starship HLS vehicle in Earth orbit for lunar transit and lunar landing operations, a capability referred to as orbital refueling. Starship HLS would then boost itself to lunar orbit for rendezvous with Orion. In the mission concept, a NASA Orion spacecraft would carry a NASA crew to the lander, where they would depart and descend to the surface of the Moon. After lunar surface operations, Starship HLS would lift off from the lunar surface acting as a single-stage-to-orbit (SSTO) vehicle and return the crew to Orion.
Blue Origin HLS
On May 19, 2023, NASA announced an additional contract to Blue Origin to develop a second crewed lunar lander, which will make its first crewed flight as part of the Artemis V mission. Blue Moon is smaller than the SpaceX HLS lander, having only 20 tons of payload capacity. The lander is fueled with a combination of liquid hydrogen and liquid oxygen propellants.
Lunar Gateway
NASA's Gateway is an in-development mini-space station in lunar orbit intended to serve as a solar-powered communication hub, science laboratory, short-term habitation module, and holding area for rovers and other robots. While the project is led by NASA, the Gateway is meant to be developed, serviced, and used in collaboration with commercial and international partners: Canada (Canadian Space Agency) (CSA), Europe (European Space Agency) (ESA), and Japan (JAXA).
The Power and Propulsion Element (PPE) started development at the Jet Propulsion Laboratory during the now canceled Asteroid Redirect Mission (ARM). The original concept was a robotic, high performance solar electric spacecraft that would retrieve a multi-ton boulder from an asteroid and bring it to lunar orbit for study. When ARM was canceled, the solar electric propulsion was repurposed for the Gateway. The PPE will allow access to the entire lunar surface and act as a space tug for visiting craft. It will also serve as the command and communications center of the Gateway. The PPE is intended to have a mass of 8–9 tonnes and the capability to generate 50 kW of solar electric power for its ion thrusters, which can be supplemented by chemical propulsion.
The Habitation and Logistics Outpost (HALO), also called the Minimal Habitation Module (MHM) and formerly known as the Utilization Module, will be built by Northrop Grumman Innovation Systems (NGIS). A single Falcon Heavy equipped with an extended fairing will launch the PPE together with the HALO in 2027. The HALO is based on a Cygnus Cargo resupply module to the outside of which radial docking ports, body mounted radiators (BMRs), batteries and communications antennae will be added. The HALO will be a scaled-down habitation module, yet, it will feature a functional pressurized volume providing sufficient command, control, and data handling capabilities, energy storage and power distribution, thermal control, communications and tracking capabilities, two axial and up to two radial docking ports, stowage volume, environmental control and life support systems to augment the Orion spacecraft and support a crew of four for at least 30 days.
In late October 2020, NASA and European Space Agency (ESA) finalized an agreement to collaborate in the Gateway program. ESA will provide a habitat module in partnership with JAXA (I-HAB) and a refueling module (ESPRIT). In return, Europe will have three flight opportunities to launch crew aboard the Orion crew capsule, for which they will provide the service module.
In 2024, the HALO module reached substantial completion and entered into the stress test phase, following successful completion of which it will be shipped from Europe to the US in preparation for configuration with the PPE module and launch.
Astronauts
On January 10, 2020, NASA's 22nd astronaut group, nicknamed the "Turtles", graduated and were assigned to the Artemis program. The group includes two Canadian Space Agency (CSA) astronauts. The group earned their nickname from the prior astronaut group, "The 8-Balls", as is a tradition dating back to "The Mercury Seven" in 1962 which subsequently provided the "Next Nine" with their nickname. They were given this name, for the most part, because of Hurricane Harvey. Some of the astronauts will fly on the Artemis missions to the Moon and may be part of the first crew to fly to Mars.
Artemis team
On December 9, 2020, vice president Mike Pence announced the first group of 18 astronauts (all American, including 9 male and 9 female from different backgrounds), the 1st Artemis team, who could be selected as astronauts of early missions of the Artemis program:
Joe Acaba
Kayla Barron
Raja Chari
Matthew Dominick
Victor Glover
Warren Hoburg
Jonny Kim
Christina Koch
Kjell Lindgren
Nicole Mann
Anne McClain
Jessica Meir
Jasmin Moghbeli
Kathleen Rubins
Frank Rubio
Scott Tingle
Jessica Watkins
Stephanie Wilson
Chief Astronaut Reid Wiseman said in August 2022, however, that all 42 active members of the NASA Astronaut Corps, and the ten more training as NASA Astronaut Group 23, are eligible for Artemis II and later flights.
Planned surface operations
The Artemis Base Camp will support missions of up to two months and will be used to study technologies to use on future Moon or Mars bases, and then future stationary modules may be used regularly for decades to come through both Government and commercial programs. Most probably it will be a site that has already been visited by prior robotic missions. It will consist of three main modules:
The Surface Habitat (SH) modules, which is the initial dwelling structure and a surface home base for the first residents of the Moon.
The Lunar Terrain Vehicle (LTV), which is an unpressurized rover cart for transporting suited astronauts and cargo around in the vicinity of the Base.
The Pressurized Rovers (PR), a pressurized vehicle complete with small backup habitation facilities, thus enabling multi-day and longer-range explorations tens of kilometers away from the Base.
Transportation on the Moon
Landing zone
In 2022, NASA has identified 13 candidate regions near the lunar South Pole for initial landing and inspection missions.
Ground transportation development
In February 2020, NASA released two requests for information regarding both a crewed and uncrewed unpressurized surface rover. The latter, Lunar Terrain Vehicle (LTV) would be prepositioned by a CLPS vehicle before the Artemis III mission. It would be used to transport crews around the exploration site and serve a similar function to the Apollo Lunar Roving Vehicle. In July 2020, NASA established a program office for the rover at the Johnson Space Center in Houston.
NASA has specified its need for a Lunar Terrain Vehicle (LTV) that has a cargo capacity of 800 kg, traversal distances of up to 20 km without battery recharging, continuous operations for 8 hours within a 24-hour period, the ability to survive the lunar night, and the ability to traverse grades as steep as ±20 degrees.
On April 3, 2024, NASA announced that Intuitive Machines, Lunar Outpost and Venturi Astrolab are the three companies developing the LTV in a 12-month feasibility and demo phase. A source selection statement by NASA provided further details on cost and overall feasibility on April 9, 2024. The Intuitive Machines proposal was for $1.692 billion, Lunar Outpost for $1.727 billion and Astrolab for $1.928 billion to develop the vehicle.
Shelter building construction
The Artemis Base Camp is the proposed lunar base to be established at the end of the 2020s. The Base camp is to be located in the south pole region near the two adjacent Shackleton and de Gerlache craters, due to this area's wide variety of lunar geography and also due to the abundance of water ice that is believed to exist in the lunar soils of the crater floors. The environs of these craters fall under the guidelines of the Outer Space Treaty.
Foundational Surface Habitat
Most of the information about the Surface Habitat (SH) modules comes from studies and launch manifests which include a reference to its launch. It will be commercially built and commercially launched in the early 2030s along with the Pressurized Vehicle (PV). The SH was formerly referred to as the Artemis Surface Asset. Launch plans showed that landing it on the surface would be similar to the HLS. The SH would be sent to the Gateway where it would then be attached to a descent stage and subsequently transported to the lunar surface with a commercial launcher and lander. It would use the same lunar transfer stage as used for the HLS. Other designs from 2019 envisioned it being launched from an SLS Block 1B as a single unit and landing directly on the surface. It would then be hooked up to a surface power system launched by a CLPS mission and tested by the Artemis VI crew. The Italian Space Agency signed a contract with Thales Alenia Space in late 2023 for the Multi Purpose Habitat, which may become the second module for the Artemis Base Camp.
Resource prospecting and research programs
As of February 2020, a lunar stay during a Phase 1 Artemis mission will be about seven days and will have five extravehicular activities (EVA). A notional concept of operations, i.e., a hypothetical but possible plan, would include the following: On Day 1 of the stay, astronauts touchdown on the Moon but do not conduct an EVA. Instead, they prepare for the EVA scheduled for the next day, in what is referred to as "The Road to EVA".
On Day 2, the astronauts open the hatch on the Human Landing System and embark on EVA 1, which will be six hours long. It will include collecting a contingency sample, conducting public affairs activities, deploying the experiment package, and acquiring samples. The astronauts will stay close to the landing site on this first EVA. EVA 2 begins on day 3. The astronauts characterize and collect samples from permanently shadowed regions. Unlike the previous EVA, the astronauts will go farther from the landing site, up to , and up and down slopes of 20°.
Day 4 will not include an EVA, but Day 5 will. EVA 3 may include activities such as collecting samples from an ejecta blanket. Day 6 will have the two astronauts deploy a geotechnical instrument alongside an environmental monitoring station for in-situ resource utilization (ISRU). Day 7 will have the final and shortest EVA. This EVA will last one hour, rather than the others' six hours in duration from egress to ingress, and mostly comprises preparations for the lunar ascent, including jettisoning hardware. Once the final EVA is concluded, the astronauts will return to the Human Landing System and the vehicle will launch from the surface and join up with Orion/Gateway.
Pressurized rover ("Mobile Habitat")
The Pressurized Rover (PR) is a large, pressurized module used to enable crewed operation across large distances and live for multiple days. NASA had developed multiple pressurized rovers including what was formerly called the Space Exploration Vehicle (SEV). This rover was built for the Constellation program and was fabricated and then tested. In the 2020 flight manifest it was later referred to as the "Mobile Habitat" suggesting it could fill a similar role to the ILREC Lunar Bus. It would be ready for the crew to use on the surface but could also be autonomously controlled from the Gateway or other locations.
Mark Kirasich, who is the acting director of NASA's Advanced Exploration Systems, has stated that the current plan is to partner with JAXA and Toyota to develop a closed cabin rover to support crews for up to 14 days (currently known as Lunar Cruiser). "It's very important to our leadership at the moment to involve JAXA in a major surface element", he said. "... The Japanese, and their auto industry, have a very strong interest in rover-type things. So, there was an idea to—even though we have done a lot of work—to let the Japanese lead development of a pressurized rover. So right now, that's the direction we're heading in".
In regard to the PR, senior-lunar-scientist Clive Neal said "Under Constellation, NASA had a sophisticated rover put together. It's pretty sad if it's never going to get to the Moon". However Neal also said that he understands the different mission objectives between the Constellation Program and those of the Artemis Program, and the need of the Artemis Program to focus more on international collaboration.
On April 9, 2024, it was announced that JAXA and NASA had signed an agreement stipulating that Japan would join the pressurized rover collaboration venture and would design, develop, and operate a rover for crewed and uncrewed exploration of the Moon. In return, NASA will provide the launch and delivery of the rover to the Moon, as well as providing seats for two Japanese astronaut missions to the lunar surface, with the goal of these astronauts being the first non-Americans to travel to the Moon's surface. The pressurized rover is planned to accommodate two astronauts for up to 30 days outside. NASA plans to use the pressurized rover from Artemis VII and subsequent missions, over an approximate 10 year lifespan.
Specialized lunar equipment development
Artemis space suits
The Artemis program will make use of two types of space suit revealed in October 2019: the Exploration Extravehicular Mobility Unit (xEMU), and the Orion Crew Survival System (OCSS).
On August 10, 2021, a NASA Office of Inspector General audit reported a conclusion that the spacesuits would not be ready until April 2025 at the earliest, likely delaying the mission from the then planned late 2024. In response to the IG report, SpaceX indicated that they could provide the suits.
Commercial spacesuits
NASA published a draft RFP to procure commercially-produced spacesuits in order to meet the 2024 schedule. On June 2, 2022, NASA announced that commercially produced spacesuits would be developed by Axiom Space and Collins Aerospace. In early 2024, the development reached the critical design and test phase.
Artemis flights
Orion testing
A prototype version of the Orion Crew Module was launched on Exploration Flight Test-1 on December 5, 2014 atop a Delta IV Heavy rocket. Its reaction control system and other components were tested during two medium Earth orbits, reaching an apogee of and crossing the Van Allen radiation belts before making a high-energy re-entry at .
The Ascent Abort-2 test on July 2, 2019 tested the final iteration of the launch abort system on a Orion boilerplate at maximum aerodynamic load, using a custom Minotaur IV-derived launch vehicle built by Orbital ATK.
Artemis I–VI
, all crewed Artemis missions will launch on the Space Launch System from Kennedy Space Center Launch Complex 39B. Current plans call for some supporting hardware to be launched on other vehicles and from other launch pads.
Artemis VII–XI
In November 2021, plans to return humans to the Moon in 2024 were cancelled, and the Artemis III mission was delayed until at least 2025. It has since been delayed to mid-2027. Artemis VII is expected to deliver a crew of four astronauts to a surface lunar outpost known as the Foundation Habitat, along with the Mobile Habitat, which is expected to occur in March 2032. The Foundation Habitat would be launched back to back with the Mobile Habitat by an undetermined super heavy launcher and would be used for extended crewed lunar surface missions.
Prior to each crewed Artemis mission, payloads to the Gateway, such as refueling depots and expendable elements of the lunar lander, would be deployed by commercial launch vehicles. The most updated manifest includes missions suggested in NASA's timelines that have not been designed or funded from Artemis IV to IX.
Support missions schedule
Artemis support missions are robotic missions flown through the CLPS program and Gateway program, and HLS demo and delivery missions.
Criticism
The Artemis program has received criticism from several space professionals.
Mark Whittington, who is a contributor to The Hill and an author of several space exploration studies, stated in an article that the "lunar orbit project doesn't help us get back to the Moon".
Aerospace engineer, author, and Mars Society founder Robert Zubrin has voiced his distaste for the Gateway, which is part of the Artemis program as of 2027. He presented an alternative approach to a 2024 crewed lunar landing called "Moon Direct", a successor to his proposed Mars Direct. His vision phases out the SLS and Orion, replacing them with the SpaceX launch vehicles and SpaceX Dragon 2. It proposes using a heavy ferry/lander that would be refueled on the lunar surface via in situ resource utilization and transfer the crew from LEO to the lunar surface. The concept bears a heavy resemblance to NASA's own Space Transportation System proposal from the 1970s.
Apollo 11 astronaut Buzz Aldrin disagrees with NASA's current goals and priorities, including their plans for a lunar outpost. He questioned the benefit of the idea to "send a crew to an intermediate point in space, pick up a lander there and go down". However, Aldrin expressed support for Robert Zubrin's "Moon Direct" concept which involves lunar landers traveling from Earth orbit to the lunar surface and back.
The program attracted criticism for the fact that at least 15 launches will be required to refuel HLS in orbit per crewed mission. In 2024, SpaceX's Jennifer Jensen stated on a call that Starship HLS will require ten launches.
Gallery
See also
Chinese Lunar Exploration Program – Chinese crewed lunar program with international partners e.g. Russia.
List of Artemis Astronauts
First Lunar Outpost – Crewed lunar program proposal from the SEI
List of missions to the Moon
NASA Astronaut Group 23
Coordinated Lunar Time
Notes
References
Sources
External links
Moon to Mars portal at NASA
Artemis program at NASA
Monthly report by the Exploration Systems Development (ESD)
View Artemis I in NASA's Eyes Eyes on the Solar System – NASA/JPL
Artemis program
2010s in the United States
2020s in the United States
2020s in spaceflight
Orion (spacecraft)
Commercial Lunar Payload Services
Exploration of the Moon
Human spaceflight programs
NASA programs
Projects established in 2017 | Artemis program | [
"Engineering"
] | 11,396 | [
"Space programs",
"Human spaceflight programs"
] |
60,758,754 | https://en.wikipedia.org/wiki/Coral%20Reef%20Conservation%20Program | Coral Reef Conservation Program (CRCP) is a partnership between National Oceanic and Atmospheric Administration (NOAA) agencies, established in 2000. The program is a multidisciplinary approach, initiated by the NOAA, to managing and understanding coral reef ecosystems through research and the publication of data to support relevant partners involved in coral reef restoration.
Background
The CRCP was established by the Coral Reef Conservation Act 2000 and Presidential Executive Order 13089, in order to fulfil the NOAA's obligations under these statutes.
The main role of the CRCP is to gather and present scientific information that coastal and marine resource managers and other decision-makers require, to address the various threats facing coral reef ecosystems in U.S. and surrounding waters. The CRCP's priority threats are climate change, unsustainable fishing practices and pollution. Monitoring the effects of these threats on the condition of U.S. coral reef ecosystems is the primary responsibility of the CRCP. Each year NOAA divers survey coral reefs at nearly 1600 sites to monitor these effects.
All research and data collected by the CRCP is publicly available on the Coral Reef Information System. Other than ecosystem monitoring, other tasks conducted by the CRCP include mapping of coral reef habitats, forecasting oceanographic conditions, and communications and data management.
As well as conducting research, the CRCP also financially supports a number of partners including institutions of higher education and not-for-profit organisations, by awarding grants to projects involved in coral reef ecosystem management and restoration. The program aims to fund at least $8 million in grants each year to partners involved in coral reef conservation management projects. In the 2018 Fiscal Year, the program contributed more than $26 million in funding towards coral reef projects across the U.S, through grants and agreements. Funding for the CRCP is provided by the NOAA and the U.S. Fish and Wildlife Service.
Agencies Involved
The CRCP is made up of several NOAA Line Offices including the National Ocean Service, the National Marine Fisheries Service, the Office of Oceanic and Atmospheric Research, and the National Environmental Satellite, Data and Information Service.
The National Ocean Service is the NOAA partner that is responsible for overseeing budget activities for the CRCP and other NOAA agencies. The National Ocean Service also conducts a number of partnered activities with the CRCP including mapping and monitoring of coral reef ecosystems.
The National Marine Fisheries Service is an agency focused on reducing and controlling the effects of overfishing, and works closely with the CRCP to manage the effects of overfishing on coral reef ecosystems
The National Environmental Satellite, Data and Information Service is another NOAA agency whose main role is to monitor coral reef indices through sensors. This data is shared with NOAA bodies including the CRCP, which is then applied to management decision making.
NOAA's Oceanic and Atmospheric Research body coordinates data collection relating to atmospheric and oceanic parameters such as climate variability and wave movement. Oceanic and Atmospheric Research is another partner of the CRCP, providing the organisation with data.
The CRCP also works closely with a number of external partners including state and territorial governments, academic institutions and non-government and intergovernmental organisations.
Objectives
The mission of the Coral Reef Conservation Program is outlined in the Coral Reef Conservation Act and can be summarised as to "protect, conserve and restore coral reef resources by maintaining healthy ecosystem functioning". The objectives of the program are consolidated into the following four key pillars, as outlined in the NOAA governmental webpage.
Increasing Resilience to Climate Change
The CRCP has adopted a resilience-based approach to addressing the issue of climate change which poses a significant threat to coral reef ecosystems by instigating coral bleaching. A resilience-based approach involves increasing the capacity of coral reef ecosystems to recover from changes in parameters and continue normal functioning. Resilience based management utilises pro-active responses rather than reactive responses that traditional management strategies tend to adopt. The CRCP's main responsibility under this approach is to continue to conduct and provide partners with the relevant information and data necessary to successfully initiate resilience-based management practices. In 2014, CRCP scientists, along with partners including the NOAA Coral Reef Watch, developed precise climate and bleaching thermal stress prediction tools. By anticipating stress events such as global bleaching outbreaks, managers can make proactive decisions to minimise the overall effects on coral reef ecosystems. One of the CRCP's targets is for at least seven of the organisation's partners to apply such climate resilience related data to climate-change orientated projects, by 2025. The CRCP also has the responsibility of initiating ongoing communication with government bodies and federal management partners on the importance of resilience-based management for the future viability of coral reefs. To fulfil this responsibility, the CRCP has developed communication plans and response plans to present information and data in a systematic and coherent manner for federal decision and policy makers. Crisis response plans are made up of early warning frameworks to prepare and protect ecosystems in response to global threat events such as coral bleaching, disease and invasive species outbreaks, and natural weather disasters such as tropical storms.
Reducing Land-based Sources of Pollution
Land-based sources of pollution pose a significant threat on coral reef ecosystems by interrupting natural processes and functioning. Reducing this threat is another pillar under the objectives of the CRCP. The CRCP regulates and supports a number of watershed management initiatives including research to identify sources of pollution, conducting studies to understand the impacts of land-based sources of pollution on coral reefs and providing financial and technical assistance to partners' watershed management responses. A key partnership under this pillar is the 'Watershed Partnership Initiative' with the U.S Coral Reef Task Force, which focuses on reducing land-based pollutants by implementing specific and integrated action responses. Watershed management includes the implementation of vegetated buffer protection along coasts, land conservation and the responsible treatment of wastewater.
Improving Fisheries' Sustainability
The success of the CRCP's ability to improve the sustainability of U.S. fisheries relies heavily on partnerships with relevant fishery management councils and agencies. There are two key strategies under this pillar, both of which involve cooperating with external partners. One of the strategies is to provide key data for coral reef fisheries management. Data collected by the CRCP is used by a number of fisheries managers working under the Magnuson-Stevens Fishery Conservation and Management Act in order to ensure that the ecological role and function that marine species play in coral reef ecosystems is sustained. The second strategy is to assist partner agencies in effectively managing coral reef fisheries. The CRCP aims for 50 percent of relevant partners to adopt effective management tools of which have been developed cooperatively. One way that the CRCP assists federal partners interested in the sustainable management of fisheries, is by supporting effective implementation and management of marine protected areas. Marine protected areas are valuable tools for restoring overexploited ecosystems and protecting fisheries.
Restoring Viable Coral Populations
The final pillar to the CRCP's strategy plan is the restoration of coral reef ecosystems. This involves supporting research of herbivore replenishment processes and collecting further data to support the prevention of avoidable losses of coral, increasing resilience and improving long-term coral health. In order to successfully enhance resilience the CRCP has recognised the need to conduct restoration projects on an international level by continuing to build foreign partnership. Restoration projects include resilience interventions such as assisted genetic adaptation, the manipulation of symbiotic relationships and larval propagation.
Projects and Initiatives
Status reports
One of the CRCP's most significant contributions to the management of U.S. coral reef ecosystems is the development of a periodic, national-level assessment on the condition of U.S. coral reef areas. The CRCP partnered with the Integration and Application Network (IAN) at the University of Maryland Centre for Environmental Science (UMES) in forming 'status reports' to present the data collected from the periodic assessments. The status reports fulfil one of the CRCP's responsibilities, as mandated by the Coral Reef Conservation Act 2000, to build an 'integrated observing system' to monitor the condition of coral reefs over time.
Both biological and physical data is collected by UMES-IAN and NOAA scientists in coral reef areas including: American Samoa, the Commonwealth of the Northern Marianna Islands, Guam, Hawaiian Archipelago, and the Pacific Remote Islands. The status reports include the assessment of several indicators which are synthesised into overall condition scores. The indicators are based on four main categories: coral and algae, fish, climate and human connections.
The purpose of the reports is to establish both a baseline and a record to track changes overtime and evaluate the overall conditions of the U.S. coral reef ecosystems. The reports are also part of CRCP's larger initiative to communicate complex information in a clear and concise manner in order to inform communities and decision-makers.
Coral Reef Information System (CoRIS)
The CRCP operates an information database known as 'CoRIS', that provides public access to all coral reef data and information collected and managed by the NOAA. This information portal is a key function of the CRCP, making data accessible to all coral reef management decision-makers. CoRIS is made up of a number of databases including the 'NOAA Deep Sea Coral Data Portal', which provides access to data relating to deep sea coral and sponges.
Outreach and education activities
One of the CRCP's responsibilities as outlined in the Coral Reef Conservation Act is to build public awareness and knowledge on the importance of sustainable management of coral reefs. The CRCP has conducted a number of educational and training workshops, and has also distributed a range of educational material regarding coral reef management, to the public.
In 2017, the CRCP developed an educational video named "A Guide to Assessing Coral Reef Resilience for Decision Support". The video was awarded first place at the 2018 CINEFISH film festival, held in Mexico.
Funding and grants
The CRCP funds a wide variety of coral reef management projects ranging from school science excursions, projects concerning the identification and mapping of coral ecosystems, the publication of educational materials and restoration initiatives.
Funding for hurricanes Irma and Maria
In 2017 Hurricanes Irma and Maria caused severe damage to the coral reefs in Florida and Puerto Rico, impacting ecosystem vulnerability and resilience. Funding to assist coral restoration was provided by the NOAA's CRCP and partners including the National Fish and Wildlife Foundation and National Marine Fisheries Service. The program led efforts to assess the impact of the hurricanes on local coral reef ecosystems and restore damage. The funds were used towards research and assessment to collect data on the impact of the hurricanes on the reefs and other crucial information, vital for effective decision-making. It was found that overturned coral reefs in Puerto Rico appeared to have macroalgal overgrowth, as evident in the figure, as a result of stress from the 2017 hurricanes. Scientists are concerned with the rapid growth of this macroalgae, and such findings are vital for effective management decision-making for the coral reef ecosystem
Funding the Hawaii Coastal Uses Mapping Project
The CRCP funds a number of projects and programs that are interested in the sustainable management of U.S. coral reef ecosystems, including the Hawaii Coastal Uses Mapping Project. The project involved gathering data and information on the impact of human activity near coastal environments on coral reef ecosystems surrounding Hawaii, by using a participatory geographic information systems (PGIS) methodology. PGIS is an effective means to obtain critical sociospatial information which includes data regarding the location of resources and the location of ecosystem related concerns, and is very useful information for a number of stakeholders involved in coastal ecosystem management including state and federal managers. Prior to the implementation of the program there was very little sociospatial data collected on the Hawaii coast.
Funding Research
The CRCP provides financial support to a number of institutional organisations with the purpose of funding and supporting the development of research papers interested in the restoration and protection of coral reef ecosystems. In 2015 the NOAA CRCP funded a study run by the Florida International University, which found that 'grazing fish can help save imperilled coral reefs'. The CRCP has also funded a number of studies on the impacts of climate change on coral reefs and the effectiveness of new management strategies. The article 'Climate-smart Design for Ecosystem Management' from the Environmental Management Journal, was partly funded by the CRCP and examines and assesses adaptation strategies for coral reefs.
References
Oceanographic organizations
Hydrology organizations
Earth sciences organizations
National Oceanic and Atmospheric Administration | Coral Reef Conservation Program | [
"Environmental_science"
] | 2,549 | [
"Hydrology",
"Hydrology organizations"
] |
60,758,873 | https://en.wikipedia.org/wiki/Chlorobactane | Chlorobactane is the diagenetic product of an aromatic carotenoid produced uniquely by green-pigmented green sulfur bacteria (GSB) in the order Chlorobiales. Observed in organic matter as far back as the Paleoproterozoic, its identity as a diagnostic biomarker has been used to interpret ancient environments.
Background
Chlorobactene is a monocyclic accessory pigment used by green sulfur bacteria to capture electrons from wavelengths in the visible light spectrum. Green sulfur bacteria (GSB) live in anaerobic and sulfidic (euxinic) zones in the presence of light, so they are found most often in meromictic lakes and ponds, sediments, and certain regions of the Black Sea. The enzyme CrtU converts γ-carotene into chlorobactene by shifting the C17 methyl group from the C1 site to the C2 site.
Preservation
Following transport and burial, diagenetic processes saturate the hydrocarbon chain, turning it into the fully saturated structure of chlorobactane.
Isoreneiratene is an aromatic light-harvesting molecule interpreted as a biomarker for brown-pigmented GSB in the same order, Chlorobiales, and its fossil form (isorenieratane) is often found co-occurring with chlorobactene in ancient organic material. Purple sulfur bacteria (PSB) also live in euxinic regions. They produce a different accessory pigment, okenone, that is preserved as okenane and often observed co-occurring with chlorobactane.
Measurement techniques
Gas chromatography coupled to mass spectrometry (GC/MS)
Organic molecules are first extracted from rocks using solvents, capitalizing on chemical properties like the polarity of the molecules to dissolve the molecules. Usually, less than one percent of the organic material from a rock is successfully pulled out in this process, leaving behind undissolved material called kerogen. The organic-rich extract is subsequently purified using silica gel column packed chromatography – eluting the extract through the column with targeted solvents pulls out contaminants and remnant undissolved organic material, which will bind to the polar silica moieties. When the sample is then run through a gas chromatography (GC) column, the compounds separate based on their boiling points and interaction with a stationary phase within the column. The temperature ramping of a gas chromatography column can be programmed to obtain optimal separation of the compounds. After the GC, the molecules are ionized and fragmented into smaller, charged molecules. A mass spectrometer then separates the individual compounds based on their mass-to-charge (M/Z) ratio and measures their relative abundance, producing a characteristic mass spectrum. Peaks representing the relative abundance of the compounds are identified as molecules based on their relative retention times, matches to a library of mass spectra with known compound identities, and comparison to standards.
Case Study: Ocean Euxinia
Because green-pigmented green sulfur bacteria require higher light intensities than their brown-pigmented counterparts, the presence of chlorobactane in the rock record has been used as key evidence in interpretations for a very shallow euxinic layer in the ocean. The euxinic zone may have changed depth in the ocean at various points in Earth's history, such as with the advent of an oxygenated atmosphere around 2.45 billion years ago and the shallowing of the oxic zone within the last six kyr.
See also
Green sulfur bacteria (GSB)
Carotenoid
Isorenieratene
Purple sulfur bacteria (PSB)
Okenane
References
Carotenoids
Chlorobiota | Chlorobactane | [
"Biology"
] | 770 | [
"Biomarkers",
"Carotenoids"
] |
60,760,613 | https://en.wikipedia.org/wiki/Circular%20procurement | Circular procurement is an approach to government procurement that enables private and public authorities to support a transition to a circular economy. This is done by purchasing works, goods, or services designed to create closed energy and material loops within supply chains while minimizing, or avoiding, the generation of waste and other negative factors on the environment. The circular procurement approach builds on the sustainable procurement approach by adding elements such as the closed-loop use of materials.
Policy context
The European Union (EU) Action Plan for the Circular Economy has implemented a comprehensive program aimed at enhancing the sustainability of product life cycles. This plan acknowledges public procurement as a significant factor in the shift towards a circular economy and outlines various measures that the European Commission will implement to promote the incorporation of circular economy principles in Green Public Procurement (GPP). These measures involve emphasizing circular attributes in revised or new sets of EU GPP criteria.
Circular public procurement also has a role in achieving the Sustainable Development Goals (SDGs), defined by the United Nations 2030 Agenda for Sustainable Development. In particular, SDG 12 – Responsible Consumption and Production – includes a specific target on promoting sustainable public procurement practices, in accordance with national policies and priorities.
Furthermore, many countries, regions, and cities have been developing their circular strategies in which public procurement is often emphasized as a key mechanism for scaling up the transition to a circular economy.
Three levels of circular procurement
There are three types or levels of models for implementing circular procurement:
System level concerns the contractual methods the purchasing organization can use to ensure circularity. For example, supplier take-back agreements or product service systems.
Supplier level pertains to how suppliers can build circularity into their systems and processes to ensure the products and services they offer meet circular procurement criteria.
Product level focuses solely on the products that suppliers to public authorities may themselves procure further down the supply chain.
Benefits
Besides sustainable procurement, circularity in procurement make buyers take a more comprehensive approach – from the first stages of procurement to the end of product life – while achieving financial benefits. Other benefits of the circular procurement include reduced environmental harm and a closed loop system which has 100% recovery and a negligible landfill ratio. By 2025, at a global scale, it has an estimated potential to add $1 trillion to the global economy and create 100,000 new jobs within the next five years.
References
Further reading
Environmental economics | Circular procurement | [
"Environmental_science"
] | 479 | [
"Environmental economics",
"Environmental social science"
] |
60,763,706 | https://en.wikipedia.org/wiki/Wine/water%20paradox | The wine/water paradox is an apparent paradox in probability theory. It is stated by Michael Deakin as follows:
The core of the paradox is in finding consistent and justifiable simultaneous prior distributions for and .
Calculation
This calculation is the demonstration of the paradoxical conclusion when making use of the principle of indifference.
To recapitulate, We do not know , the wine to water ratio.
When considering the numbers above, it is only known that it lies in an interval between the minimum of one quarter wine over three quarters water on one end (i.e. 25% wine), to the maximum of three quarters wine over one quarter water on the other (i.e. 75% wine). In term of ratios, resp. .
Now, making use of the principle of indifference, we may assume that is uniformly distributed. Then the chance of finding the ratio below any given fixed threshold , with , should linearly depend on the value . So the probability value is the number
As a function of the threshold value , this is the linearly growing function that is resp. at the end points resp. the larger .
Consider the threshold , as in the example of the original formulation above. This is two parts wine vs. one part water, i.e. 66% wine. With this we conclude that
.
Now consider , the inverted ratio of water to wine but the equivalent wine/water mixture threshold. It lies between the inverted bounds.
Again using the principle of indifference, we get
.
This is the function which is resp. at the end points resp. the smaller .
Now taking the corresponding threshold (also half as much water as wine). We conclude that
.
The second probability always exceeds the first by a factor of . For our example the number is .
Paradoxical conclusion
Since , we get
,
a contradiction.
References
Probability theory paradoxes | Wine/water paradox | [
"Mathematics"
] | 380 | [
"Probability theory paradoxes",
"Mathematical problems",
"Mathematical paradoxes"
] |
60,763,744 | https://en.wikipedia.org/wiki/Associative%20interference | Associative interference is a cognitive theory established on the concept of associative learning, which suggests that the brain links related elements. When one element is stimulated, its associates can also be activated. The most known study demonstrating the credibility of this concept was Pavlov's experiment in 1927 which was later developed into the learning procedure known as classical conditioning.
However, whilst classical conditioning and associative learning both explore how the brain utilizes this cognitive association to benefit us, studies have also shown how the brain can mistakenly associate related, but incorrect elements together, and this is known as associative interference. A simple example of this would be when one was asked a series of multiplication questions. A study conducted in 1985 showed that over 90% of the mistakes subjects made were actually answers to other questions with a common multiplicand. That is, questions such as 4 x 6 = 24 and 3 x 8 = 24 were very likely to promote errors (8 x 4 = 24) due to associative interference.
Associative interference was widely investigated and researchers realized there were different types of interference, namely retroactive interference which investigates how new memories disrupts the retrieval of old memories, and proactive interference which investigates how old memories disrupts the retrieval of new memories. These two were subsequently known as the interference theory.
Therefore, associative interference is a fundamental theory which the interference theory draws upon. The essential difference between these two is time. Both retroactive and proactive interference are concerned with when the interfering elements, or memories were obtained. However, associative interference does not encompass time, as shown by the previous example. The chronological acquisition of the four times table in relation to the three times table is independent as to why subjects made an error, highlighting the difference between the two.
History
Interference in experimental literature has been a topic of interest for psychologists for over 100 years, with early studies dating back to the 1890s. Hugo Münsterberg was among the first to study this concept by recording the effects of altering some of his daily routines, such as dipping his pen in ink and taking a watch out of his pocket. He concluded that by associating the stimulus (what's the time?) with a response (taking out pocket watch), both the stimulus and response have equal likelihood to trigger automatic retrieval if the other was encountered. That is, taking out a pocket watch (response) would often trigger the action of checking the time (stimulus) even if the supposed action was something different, such as taking out the watch and placing it on the table.
Georg E. Müller and Friedrich Schumann later developed a study in 1894 researching stimuli recall. By making subjects learn a series of words composed of nonsense syllables, it was found that if an association formed between syllables 1 and 2, it was harder for subjects to associate syllable 1 with syllable 3. The phenomenon was subsequently termed the law of associative inhibition. This paved the way for future studies as many psychologists utilized a similar experimental procedure of preparing a series of stimuli for subjects to recognize and/or recall to investigate the effects of interference.
Over the course of the 19th and 20th century, various psychologists entered the field of interference study and designed their experiments with unique stimuli. John A. Bergström and many others began working with card sorting, while Linus W. Kline used stimuli which were designed to be more recognizable for subjects such as states, capitals and book titles. In the end, it was concluded that as long as the subject's brain had formed associations with the experiment stimuli, regardless of what form or shape the stimuli took interference could occur.
Impact on memory
Effect on recall
Many studies have concluded that associative interference reduces a subject's ability to recall. In 1925, Erwin A. Esper presented subjects with a series of random shapes with different colours. In total there were 4 different shapes and colours, creating 16 possible shape-colour combinations.
Each combination was then assigned a nonsensical name which followed the same rule. The first half of the name would be a syllable corresponding to its colour, whilst the second half would be a syllable corresponding to its shape. For example, the colour red would correspond to the syllable “nas”, whilst the first shape would correspond to the syllable “lin”, creating the name “naslin” for that specific combination. By presenting these combinations alongside their names to subjects to remember throughout the length of the study, they were subsequently tested by being asked to recall the name of each randomly presented combination.
The results of this study found that in cases where subjects made a mistake, a common pattern emerged. Using the previous colour-shape combination as an example, when it was presented one participant's response was “nasden”. This response seemed to be an amalgamation of “naslin” the correct answer, and the word “nasdeg” which interestingly was a name assigned to another colour-shape combination with a different shape, but also in red. This occurrence whereby the stimulus and its similar associate forms a variant were seen for other combinations as well and indicates the presence of associative interference.
Similar trends can be seen in other studies. Alison M. Dyne and her peers designed a similar experiment, however instead of colours and shapes, word pairs were used to investigate whether overlapping words from different pairs would result in associative interference during recall.
Participants were introduced to a study list with word pairs randomly sampled from a word pool which they were subsequently tested on. The pairs that were chosen consisted of a mix of ones which had unique words (where both words did not appear in any other pair on the list), and ones which had overlapping words (where one or both words appeared in other pairs on the list). They were then given one half of the word-pair, and asked to recall and write down the corresponding word for that specific pair. As hypothesised, associative interference hindered many of the participants recall ability, as they were much more likely to make a mistake in recalling overlapping word pairs.
Effect on recognition
Whilst associative interference has shown to reduce recall performance, its effects on recognition remain inconsistent.
In the previous study, participants were also tested for recognition, by providing a similar test list with interference inducing word pairs and non-interference word pairs. However, this time certain pairs from both categories were rearranged, and participants were asked to circle the pairs they thought remained the same. Surprisingly, there was no significant result to indicate the sign of associative interference as both the miss rate and accuracy rate increased under interference conditions as opposed to the recall experiment.
Michael F. Verde conducted a similar study in 2004 to further investigate how recognition is affected by interference. In his experimental method, participants were also subject to word pairs, however this time in the form of “the person is in the location”. Participants were tested in a similar manner to the previous study by being asked if the tested pair were rearranged or not. After noting the lack of any significant results to Dyne and her peers' study, Verde then introduced a new factor, the concept of familiarity. Despite the results of the recognition test not showing signs of interference, he predicted that interference conditions would increase participant's familiarity to the word pairs.
As such, a second experiment was conducted whose method was almost identical to the first. However this time instead of presenting participants with some word pairs which were rearranged, word pairs which contained words not present in the study list were added to the test list. Participants were then asked if the tested word pairs contained novel words which they hadn't seen before to investigate how familiarity affects recognition under interference and non-interference conditions. This resulted in an increase in recognition rate under interference conditions compared to the first experiment, suggesting that familiarity is a contributor to recognition performance while under the influence of associative interference.
Impact on learning
Kevin Darby and Vladimir Sloutsky's study of interference effects on memory development has shown that associative interference can have significant implications on learning as a result of its effects on memory (ref). In their study, 2 experimental studies were outlined to test the ways in which interference impacts learning.
The first one was conducted on a sample of preschool-aged participants. The stimulus presented were word pairs from 4 different categories: animals (e.g. turtle), vehicles (e.g. train), clothing (e.g. boot) and furniture (e.g. lamp) presented in a visual form. No pair contained words from the same category, and these image pairs where shown to participants alongside 2 familiar characters; Winnie the Pooh and Mickey Mouse. These two characters served as a response to test interference, as each word pair would correspond to one of the characters. Similar to prior interference studies, word pairs were either unique, or contained an overlapping word from another pair. These overlapping pairs were used to facilitate interference conditions.
After an initial phase of teaching participants what each word pair's supposed response was, they then undergone a testing phase and questioned on the proper response for each pair. The results of this experiment revealed that the young participants showed signs of interference. However, these results are all expected, and align with similar conclusions achieved from previous studies. The unique factor regarding Darby and Sloutsky's experiment was that it was repeated, this time with adult participants. Although both younger and older participants have displayed signs of interference, by directly comparing the two age groups it becomes possible to analyse the level of impact interference has with regards to age.
These subsequent experiments with adult participants concluded that certain types of interference affected children much more than adults. Therefore, it can be concluded that interference has a much bigger impact on learning during childhood and growing up than it is when an individual is much older.
Although this difference isn't substantial to the point where adults can learn more easily than children as shown by multiple studies as a result of neuroplasticity, it is important to outline the importance of interference as a hindrance towards learning in younger individuals. In particular, education systems such as schools may need to reassess certain topics and subjects if they are more difficult for students to grasp as interference may be inhibiting their ability to understand and process the information to learn and memorise it.
Proactive Interference and Retroactive interference Summary
Context
The concepts of proactive interference and retroactive interference were first introduced by the studies of verbal behavior, focusing on the use of paired-associate learning, in which a stimulus is paired with an idea or object that elicits a response. In order to observe interference using paired-associate stimuli, the target association should be similar, to some extent, to the interfering association, otherwise interference would not occur. For example, if subjects are asked to memorize word pairs (e.g., donkey-tree and dog-tree), interference will occur when two pairs share a common associate (in this example, tree). A study using paired-associate tasks by Wickens, Born, and Allen (1963) showed that if target material and interfering material decrease in similarity, a decrease in proactive interference will follow.
Proactive interference is the interfering of older memories with the retrieval of newer memories. Compared with retroactive interference, it is less common and less problematic. Proactive interference is likely to happen when memories are learned in similar contexts. An example is when motor abilities from skills that were previously learned interfere with new abilities in another skill being learned. If someone learned how to drive a stick shift first, and has driven a stick shift for a long time, it would be harder for them to drive an automatic car. interference is also associated with poorer list discrimination, which occurs when participants are asked to judge whether an item has appeared on a previously learned list. If the items or pairs to be learned are conceptually related to one another, then proactive interference has a greater effect. Delos Wickens discovered that proactive interference build-up is released when there is a change to the category of items being learned, leading to increased processing in working memory. Presenting new skills later in practice can considerably reduce proactive interference, which is desirable for participants to have the best opportunity to encode fresh new memories into long-term memory."
Retroactive interference is the interference of newer memories with the retrieval of older memories. The learning of new memories contributes to the forgetting of previously learned memories. For example, retroactive interference would happen as an individual learns a list of Italian vocabulary words, had previously learned Spanish. Learning the Italian words would make it more difficult to remember the Spanish words. The term Retroactive Interference was first brought up by Muller and colleagues; they demonstrated that if the retention interval (the amount of time between stimulus presentation and recall) was filled with tasks and material, interference would be caused with the previously learned items. Retroactive interference may have larger effects than proactive interference because it not only involves competition between previously learned material and new material, but it also involves unlearning.
Paired-associate learning
One strategy used to understand how people encode and retrieve memory associations is called paired-associate learning. In a typical study using paired-associate learning, subjects would be presented with pairs of unrelated words (cat, phone) and then memory for those word pairs would be tested. Results from Rohwer’s (1966) studies on paired-associate learning indicate that subjects have increased recall ability when words are associated with a specific context than without such context. For example, subjects would perform better in a recalling task if the sentence “The COW chased the BALL” than if they simply tried to remember the words cow and ball., which seems to support the claim that elaborative rehearsal can improve memory. Other research by Bobrow and Bower (1969) indicated that subject-generated sentences were better recalled than experimenter-generated sentences, suggesting that self-generated sentences improved word pair recall. Bower (1969) also suggested that if experimenters try to control subject’s spontaneous elaboration in the control group by telling them to repeat the words over and over (without making any elaborative rehearsal), recall would be negatively affected.
References
Memory
Psychological theories
Neuroscience | Associative interference | [
"Biology"
] | 2,887 | [
"Neuroscience"
] |
60,763,954 | https://en.wikipedia.org/wiki/OnePlus%207 | The OnePlus 7 and OnePlus 7 Pro (stylized as “OnePlus 7Pro”) are Android smartphones manufactured by OnePlus. They were unveiled on 14 May 2019.
Specifications
Design
Both phones have a metal/glass construction, with an anodized aluminium frame and Gorilla Glass 5 on both the front and back. The OnePlus 7 opts for a more conservative design with a notch, resembling the 6T, while the OnePlus 7 Pro has a near-full screen curved display with an 88.1% screen-to-body ratio. Both are available in Mirror Gray; Mirror Red and Mirror Blue are exclusive to the 7 while Almond and Nebula Blue are exclusive to the 7 Pro.
Hardware
Internally, both use the Snapdragon 855 processor with the Adreno 640 GPU. Both phones are available with either 128 or 256 GB of storage, although the 7 Pro is available with 12 GB of RAM in addition to the 6 and 8 GB variants on the 7. A version of the OnePlus 7 with 12 GB of RAM is available in China. Both phones have an AMOLED display, but the 7 Pro has a slightly larger 1440p screen as opposed to the 7's 1080p screen. The 7 Pro also has a faster 90 Hz refresh rate, rivaling gaming phones such as the ROG Phone and the Razer Phone. Both phones have stereo speakers with active noise cancellation as well. Due to the larger screen, the 7 Pro is also physically larger and has a 4000 mAh battery, the largest in a OnePlus phone. The 7 uses a 3700 mAh battery, which is the same capacity as the 6T's. Power and data connections are provided through the USB-C port; both support fast charging with the 7 rated at 20W and the 7 Pro rated at 30W. Biometric options include an optical (under-screen) fingerprint sensor and facial recognition.
Camera
The 7 Pro's all-screen design is enabled by a motorized pop-up selfie camera. The motor is rated as being capable of surviving up to 300,000 actuations. The phone will warn users if they are using the camera too often, and has fall detection which automatically retracts the camera. A warning will also be displayed if the camera is pushed back in manually. Both phones have a 16 MP sensor for the front camera, but the 7 Pro's rear cameras are noticeably upgraded. The primary sensor is 48 MP with OIS; the 7 has a 5 MP depth sensor, while the 7 Pro has a 16 MP wide-angle sensor and an S5K3M3 8 MP telephoto sensor.
Software
OnePlus released OxygenOS 12 H.41 for the 7 and 7 Pro, based on Android 12, but not the OnePlus 7 Pro 5G, which remains on OxygenOS 10.
Although the software maintenance schedule given by OnePlus mentions only two Android upgrades, the devices without 5G received these 2 upgrades to OxygenOS 10 and OxygenOS 11, and then OnePlus delivered a final upgrade to OxygenOS 12 to match the OnePlus 7T and 7T Pro, which each received only 2 upgrades, ending on the same version of OxygenOS.
Network compatibility
Notes: * denotes global, ** denotes North America
The regular OnePlus 7 was not available in the United States.
Variants
Both OnePlus 7 and OnePlus 7 Pro have several variants. The differences are usually with the supported brands. The pricing for the OnePlus 7 varied across international markets. OnePlus 7 has been sold for as much as $690 in Europe but later got a price reduction, retailing for as low as $465 when purchased directly from OnePlus. A Mirror Blue variant, which was launched in India, cost roughly $480. The price of the base model of OnePlus 7 Pro was around $670 while its higher end variants were sold for as much as $749.
Reception
The OnePlus 7 Pro was received positively, with CNET giving it an 8.8/10, The Verge giving it an 8.5/10, Wired giving it an 8/10 and Engadget giving it a 91. The screen, performance, cameras and design were all praised, but it received some criticism for the lack of an IP Rating, wireless charging and a headphone jack. Engadget called it "a beast of a device that delivers fantastic mobile cinematic plus gaming experience, and one that’s in a well-designed package".
The 7 Pro received a score of 111 from DxOMark, it ranked as the third best smartphone camera at the time behind the P30 Pro and Galaxy S10 5G. It has a photo score of 118 and a video score of 98.
Marques Brownlee considered the 7 Pro to be the smartphone of 2019 because it "felt like the best, most complete smartphone of the year".
See also
Comparison of ARMv8-A cores, ARMv8 family
List of Qualcomm Snapdragon processors
References
External links
OnePlus mobile phones
Mobile phones introduced in 2019
Mobile phones with multiple rear cameras
Mobile phones with 4K video recording
Discontinued flagship smartphones | OnePlus 7 | [
"Technology"
] | 1,074 | [
"Discontinued flagship smartphones",
"Flagship smartphones"
] |
60,765,233 | https://en.wikipedia.org/wiki/Microarchitectural%20Data%20Sampling | The Microarchitectural Data Sampling (MDS) vulnerabilities are a set of weaknesses in Intel x86 microprocessors that use hyper-threading, and leak data across protection boundaries that are architecturally supposed to be secure. The attacks exploiting the vulnerabilities have been labeled Fallout, RIDL (Rogue In-Flight Data Load), ZombieLoad., and ZombieLoad 2.
Description
The vulnerabilities are in the implementation of speculative execution, which is where the processor tries to guess what instructions may be needed next. They exploit the possibility of reading data buffers found between different parts of the processor.
Microarchitectural Store Buffer Data Sampling (MSBDS),
Microarchitectural Load Port Data Sampling (MLPDS),
Microarchitectural Fill Buffer Data Sampling (MFBDS),
Microarchitectural Data Sampling Uncacheable Memory (MDSUM),
Transactional Asynchronous Abort (TAA), CVE-2019-11135
Not all processors are affected by all variants of MDS.
History
According to Intel in a May 2019 interview with Wired, Intel's researchers discovered the vulnerabilities in 2018 before anyone else. Other researchers had agreed to keep the exploit confidential as well since 2018.
On 14 May 2019, various groups of security researchers, amongst others from Austria's Graz University of Technology, Belgium's Catholic University of Leuven, and Netherlands' Vrije Universiteit Amsterdam, in a disclosure coordinated with Intel, published the discovery of the MDS vulnerabilities in Intel microprocessors, which they named Fallout, RIDL and ZombieLoad. Three of the TU Graz researchers were from the group who had discovered Meltdown and Spectre the year before.
On 12 November 2019, a new variant of the ZombieLoad attack, called Transactional Asynchronous Abort, was disclosed.
Impact
According to varying reports, Intel processors dating back to 2011 or 2008 are affected, and the fixes may be associated with a performance drop. Intel reported that processors manufactured in the month before the disclosure have mitigations against the attacks.
Intel characterized the vulnerabilities as "low-to-medium" impact, disagreeing with the security researchers who characterized them as major, and disagreeing with their recommendation that operating system software manufacturers should completely disable hyperthreading. Nevertheless, the ZombieLoad vulnerability can be used by hackers exploiting the vulnerability to steal information recently accessed by the affected microprocessor.
Mitigation
Fixes to operating systems, virtualization mechanisms, web browsers and microcode are necessary.
, applying available updates on an affected PC system was the most that could be done to mitigate the issues.
Intel incorporated fixes in its processors starting shortly before the public announcement of the vulnerabilities.
On 14 May 2019, a mitigation was released for the Linux kernel, and Apple, Google, Microsoft, and Amazon released emergency patches for their products to mitigate ZombieLoad.
On 14 May 2019, Intel published a security advisory on its website detailing its plans to mitigate ZombieLoad.
See also
Transient execution CPU vulnerabilities
Hardware security bug
References
Further reading
Original papers by the researchers
Information from processor manufacturers
External links
Official disclosure website of ZombieLoad
RIDL and Fallout: MDS attacks Vrije Universiteit Amsterdam
Transient execution CPU vulnerabilities
Intel x86 microprocessors
2019 in computing
X86 memory management | Microarchitectural Data Sampling | [
"Technology"
] | 721 | [
"Transient execution CPU vulnerabilities",
"Computer security exploits"
] |
60,765,961 | https://en.wikipedia.org/wiki/Eugene%20Catalan%20Prize | The Eugene Catalan Prize (Prix Eugène-Catalan) is awarded every five years by the Royal Academies for Science and the Arts of Belgium to recognize a scholar who has made important progress in pure mathematics. The prize, created in honor of the mathematician Eugène Charles Catalan, was first given in 1969; the original criteria specified Belgian or French scholars but European Union citizens are now eligible.
Recipients
The recipients of the Eugene Catalan Prize are:
2020: Antoine Gloria
2015: Pierre Bieliavsky
2010:
2005: Didier Smets
2000: Jean-Michel Coron
1995: Jean-Pierre Tignol
1990: Haïm Brezis
1979: Roger Apéry
1974: J. Goffar-Lombet
1969: Gilbert Crombez
See also
List of mathematics awards
References
Mathematics awards | Eugene Catalan Prize | [
"Technology"
] | 158 | [
"Science and technology awards",
"Mathematics awards"
] |
60,766,435 | https://en.wikipedia.org/wiki/Express%20Data%20Path | XDP (eXpress Data Path) is an eBPF-based high-performance network data path used to send and receive network packets at high rates by bypassing most of the operating system networking stack. It is merged in the Linux kernel since version 4.8. This implementation is licensed under GPL. Large technology firms including Amazon, Google and Intel support its development. Microsoft released their free and open source implementation XDP for Windows in May 2022. It is licensed under MIT License.
Data path
The idea behind XDP is to add an early hook in the RX path of the kernel, and let a user supplied eBPF program decide the fate of the packet. The hook is placed in the network interface controller (NIC) driver just after the interrupt processing, and before any memory allocation needed by the network stack itself, because memory allocation can be an expensive operation. Due to this design, XDP can drop 26 million packets per second per core with commodity hardware.
The eBPF program must pass a preverifier test before being loaded, to avoid executing malicious code in kernel space. The preverifier checks that the program contains no out-of-bounds accesses, loops or global variables.
The program is allowed to edit the packet data and, after the eBPF program returns, an action code determines what to do with the packet:
XDP_PASS: let the packet continue through the network stack
XDP_DROP: silently drop the packet
XDP_ABORTED: drop the packet with trace point exception
XDP_TX: bounce the packet back to the same NIC it arrived on
XDP_REDIRECT: redirect the packet to another NIC or user space socket via the AF_XDP address family
XDP requires support in the NIC driver but, as not all drivers support it, it can fallback to a generic implementation, which performs the eBPF processing in the network stack, though with slower performance.
XDP has infrastructure to offload the eBPF program to a network interface controller which supports it, reducing the CPU load. In 2023, only Netronome cards support it.
Microsoft is partnering with other companies and adding support for XDP in its MsQuic implementation of the QUIC protocol.
AF_XDP
Along with XDP, a new address family entered in the Linux kernel starting 4.18. AF_XDP, formerly known as AF_PACKETv4 (which was never included in the mainline kernel), is a raw socket optimized for high performance packet processing and allows zero-copy between kernel and applications. As the socket can be used for both receiving and transmitting, it supports high performance network applications purely in user space.
See also
Application layer
Network layer
Data link layer
References
External links
XDP documentation on Read the Docs
AF_XDP documentation on kernel.org
XDP walkthrough at FOSDEM 2017 by Daniel Borkmann, Cilium
AF_XDP at FOSDEM 2018 by Magnus Karlsson, Intel
eBPF.io - Introduction, Tutorials & Community Resources
L4Drop: XDP DDoS Mitigations, Cloudflare
Unimog: Cloudflare's edge load balancer, Cloudflare
Open-sourcing Katran, a scalable network load balancer, Facebook
Cilium's L4LB: standalone XDP load balancer, Cilium
Kube-proxy replacement at the XDP layer, Cilium
eCHO Podcast on XDP and load balancing
Command-line software
Firewall software
Linux security software
Linux kernel features
Free and open-source software
Microsoft free software
Software using the GNU General Public License
Software using the MIT license
2016 software
Free software programmed in C | Express Data Path | [
"Technology"
] | 757 | [
"Command-line software",
"Computing commands"
] |
60,767,585 | https://en.wikipedia.org/wiki/Hazel%20Perfect | Hazel Perfect (circa 1927 – 8 July 2015) was a British mathematician specialising in combinatorics.
Contributions
Perfect was known for inventing gammoids, for her work with Leon Mirsky on doubly stochastic matrices, for her three books Topics in Geometry, Topics in Algebra, and Independence Theory in Combinatorics, and for her work as a translator (from an earlier German translation) of Pavel Alexandrov's book An Introduction to the Theory of Groups (Hafner, 1959).
The Perfect–Mirsky conjecture, named after Perfect and Leon Mirsky, concerns the region of the complex plane formed by the eigenvalues of doubly stochastic matrices. Perfect and Mirsky conjectured that for matrices this region is the union of regular polygons of up to sides, having the roots of unity of each degree up to as vertices. Perfect and Mirsky proved their conjecture for ; it was subsequently shown to be true for and false for , but remains open for larger values
Education and career
Perfect earned a master's degree through Westfield College (a constituent college for women in the University of London) in 1949, with a thesis on The Reduction of Matrices to Canonical Form.
In the 1950s, Perfect was a lecturer at University College of Swansea; she collaborated with Gordon Petersen, a visitor to Swansea at that time, on their translation of Alexandrov's book.
She completed her Ph.D. at the University of London in 1969; her dissertation was Studies in Transversal Theory with Particular Reference to Independence Structures and Graphs. She became a reader in mathematics at the University of Sheffield.
Selected publications
Books
Research papers
Translation
References
2015 deaths
British mathematicians
British women mathematicians
Alumni of Westfield College
Academics of Swansea University
Academics of the University of Sheffield
German–English translators
Technical translators
Combinatorialists
Year of birth uncertain | Hazel Perfect | [
"Mathematics"
] | 374 | [
"Combinatorialists",
"Combinatorics"
] |
60,768,446 | https://en.wikipedia.org/wiki/Robert%20E.%20Rundle | Robert Eugene Rundle (1915 – 9 October 1963) was an American chemist and crystallographer. He was a professor at Iowa State University and fellow of the American Physical Society.
Early life and education
Rundle was born in Orleans, Nebraska in 1915. He attended University of Nebraska where he completed a bachelor of science in 1937 and a master's degree in 1938. He completed a Ph.D. in 1941 at the California Institute of Technology. His advisors were Linus Pauling and J. Holmes Sturdivant.
Career and research
Rundle joined Iowa State University as an assistant professor of chemistry. From 1945 to 1946, he worked at Princeton University before returning to Iowa State University as a full professor. His research was focused on x-ray diffraction by crystals, inorganic solid-state chemistry, intermetallic and interstitial compounds, hydrogen-bonded substances, compounds of uranium and thorium, and electron-deficient compounds. He was a member of the American Crystallographic Association and served as the president of the organization in 1958. He was a member of the American Association of University Professors.
Awards and honors
Rundle was a fellow of the American Physical Society.
Personal life
Rundle died from a stroke in Iowa Methodist Hospital on October 9, 1963. He was survived by his wife and three sons.
References
1915 births
1963 deaths
People from Harlan County, Nebraska
Scientists from Nebraska
20th-century American chemists
University of Nebraska alumni
Iowa State University faculty
California Institute of Technology alumni
American crystallographers
Fellows of the American Physical Society
Presidents of the American Crystallographic Association
Solid state chemists | Robert E. Rundle | [
"Chemistry"
] | 326 | [
"Solid state chemists"
] |
60,768,800 | https://en.wikipedia.org/wiki/Life%20cycle%20ritual | A life cycle ritual is a ceremony to mark a change in a person's biological or social status at various phases throughout life. Such practices are found in many societies and are often based on traditions of a community. Life cycle rituals may also have religious significance that is stemmed from different ideals and beliefs.
A life cycle ritual can best be described as a ceremony undergone by an individual when he or she enters one phase of life to another. The term may be synonymous with ‘rite of passage’ as described by Arnold van Gennep in his 1909 work ‘Rite of Passage’. although can be described as more specifically to do with major biological life events such as birth, adolescence, marriage and death. Van Gennep described society as being composed of “…several disparate social groupings”. He further divided these social groupings into either secular (financial strata, for example) or sacred (being born, getting married), the latter being the category most closely associated with life cycle rituals.
Van Gennep classified rituals as broadly belonging to one of three categories: separation, liminal and incorporation. The separation phase involves the individual leaving one group or life phase at a point in time and the incorporation phase involves them joining the new phase. The liminal phase is the transitive phase in between the two where the individual has left one phase but not yet joined the next.
The various phases of the life cycle were described by David Lancy as belonging to six practical categories: 1) Birth and early infancy, which Lancy describes as ritually being the least important given the doubt over the child's survival; 2) Joining the community when the infant's survival is confirmed, usually denoted by a naming ceremony; 3) Separation, marked by removing the child from the mother's breast or when the child starts walking; 4) Getting noticed i.e. when the child starts becoming useful, usually by beginning to help around the house; 5) Adolescence, described as being highly variable across cultures and most commonly being marked by an initiation ceremony and 6) Adulthood, which the author says in most cultures is the point when the individual sires offspring.
Birth rites begin at the indication of pregnancy and through childbirth, continuing for a variable time forth until the required conditions per individual practices are satisfied. Adolescence is also marked by a term known as “Coming of Age”, which is the transition period between childhood and adulthood. In some societies, it is described by Joseph as the change associated with the age of sexual maturity (p. 68), while in others, it is marked as the age where one adopts religious and social responsibility and standing. Initiation rights specifically involve those relating to the age during which sexual maturity is observed. However, this is very variable between societies and religions, and so the definition of maturation is derived mostly from social and cultural beliefs.
Norbeck & Alexander note that in primitive societies detached from the modern developing world, the rites of passage are limited by distinctions of sex and age. There is an absence of social status and developed religious beliefs. In culturally sophisticated societies, there are distinct divisions of labor, social statuses of the leadership and specialised occupations. Individuals are literate and learned, and possess the intellectual thinking to develop personal beliefs based on knowledge and understanding. This results in more organised practices of life cycle rituals, mostly in tune with critical biological and social events.
Life cycle ceremonies possess aspects of the symbolism that are representative of their origin. The practice of each rite and ritual has certain rules and conditions that must be adhered to. These can vary from clothing, venue, time of day, recitation of prayers and order of proceedings.
Examples of life cycle rituals
Birth
a. In India, the birth of a male is announced by the beating of a Thali (a sort of bronze utensil) by friends or relatives while a female child is announced by the beating of a fan used for winnowing
b. In most Muslim cultures, it is customary for the father or general patriarch of the family to whisper the Adhan, the Muslim call to prayer, into the child's ear as soon as possible after birth
Adolescence
a. In the Navajo tribe, the Kinaalda ceremony marks the advent of womanhood for a girl when she experiences her first menstrual cycle. The ceremony lasts several days and is composed of several discrete rituals
b. The Bar mitzvah is a coming of age ceremony for Jewish boys at the age of 13, where they read scripture from the Torah in the synagogue and a celebration is held in the boy's honor afterwards.
Marriage
a. Marriage in Renaissance Florence was usually marked by the delivery of an intricately decorated chest with the wedding procession. This chest contained the bride's dowry and would later be added to the furniture in the newlywed's bedroom.
b. In the Garo community of Bangladesh, an essential pre wedding ceremony involves the compulsory gifting of betel leaf, nuts and sweets to the groom from the bride's family.
Death
a. In the Akan culture of Ghana, the widow of a recently deceased man wears a charm necklace for the entire 40 day period of the funeral rites, so that her husband may not return to haunt her from the afterlife as believed→.
b. In Japanese Buddhist culture, after the cremation of the deceased, family and close friends use special chopsticks to pick up bone fragments and place them in an urn, which in turn must be placed in a family grave within forty nine days of the funeral.
Classification of life cycle rituals
While no scheme of classification of passage rites has been universally accepted, there is a general trend with names being given to distinguishable types and some corresponding examples:
a. Purification practices - prepare the individual for communication with the supernatural, or erasing an old status in preparation for a new one.
b. Social transformation - initiation, induction, change in status.
c. Religious transformation - sacrifice rituals, acceptance of a belief, functions related to changing life stages, circumcision.
d. Biological development - pregnancy, childbirth, birth, puberty, menopause.
e. Marital ceremonies.
f. Death - burial, cremation, prayers (include all stages of separation, transition and reincorporation).
Psychological impact
Possessing religious and cultural significance, rituals and ceremonies are noted to provide one with a sense of belonging and a deeper meaning and the understanding of their being. This applied to ones position as an individual, a follower of a certain belief and a member of society. It also fosters personal and family identity, providing a means by which one can possess a feeling of belonging. Life cycle rites also help individuals in becoming more aware, understanding and accepting of the inevitable changes in life, reducing a feeling of the possible isolation or unfamiliarity. They channel feelings of togetherness and inclusion for the closed ones of the involved individual as well.
Transitional rituals and rites of passage have profound implications on the development of the individual psyche. The decline of such initiation rites among males in today's technology and intellect driven world has been associated with a loss of identification with the male group as a whole and a lack of perceived masculinity among modern men, leading to feelings of anxiety, inadequacy and overall impotence and anger management issues.
Conversely, extremely severe initiation rituals have been found to induce a sense of cognitive dissonance within the psyche of the initiate. Individuals who undergo severe rites before joining a specific group tend to find that group more attractive due to a perceived pride and justification of effort. This fosters an inbuilt belief of superiority, as well as dissociation from personal ideals, which transform into those adopted by the group as a whole.
Rituals and ceremonies also effectively reinforce the changes corresponding to the developmental stages that they signify. A baby's identity for its family and community after birth, reminding an individual of their newly adopted responsibilities and expectations upon reaching adolescence, officiating a couples love by transforming them from lovers to committed partners in a marriage, and the preparation of a person's body as per cultural or religious standards after their death are all examples of such reflection.
Overall, the performance of rituals as part of an overall cultural identity has been found to be associated with an increased feeling of association with other members of the same group, thereby creating a sense of ‘collective unity’. In addition to that, rituals have also been found to be a way for individuals to familiarize themselves with social norms, some suggesting that the primary purpose of any ritual is to impart that informal learning to the individual and to increase his or her social awareness.
Cultural impact
The use of rituals and traditions such as weddings, bar mitzvahs, funerals and baptisms to celebrate and denote the life cycle transitions have been found to offer the members of a family to reaffirm their status and identity within the household. In addition to the reaffirmation of status within the family, the performance of rituals specific to a certain subculture also affords individuals the opportunity to identify and connect with the members of that specific subculture.
David Lancy also offers a unique perspective on the impact that the performance of life cycle rituals may have on an individual's role in society. He notes that in indigenous populations, children who undergo specific rites to denote a transition from phase of life to another are usually self-sufficient not long after puberty. In contrast, he observes that in modern bourgeoisie societies where rituals and milestones are foregone in favor of comparison to standardized development milestones, children often have a prolonged period of adolescence lasting into their twenties before they become self-sufficient, something he defines as a form of ‘learned helplessness’ .
Following cultural standards, life cycle rituals are practiced based on specific beliefs and rites. Ones acceptance of their culture, and involvement with the society, is associated with their implementation of these practices. The structural functionalism is seen to maintain societies in a “steady state” and preserve a specific status quo. Such practices relieve the stress individuals may be exposed to as a result of the significant changes and restructure they must undergo as a natural progression of growth. The rituals can assist in providing instruction and approval of the new roles that must subsequently be adopted. The resulting feeling of belonging also provides encouragement to not be disturbed or displaced by these changes, and instead welcome them as a part of life and affirm the social and moral values expressed. Hence, these sociocultural practices foster unity through communal actions.
Modern-day changes
In developed countries, as people live longer and become more affluent, there has been a shift in the practices of life cycle rituals. Newly conceptualized stages have emerged, such as “bridal shower”, “baby shower”, “bachelor/bachelorette party”, “mid-life” and “empty nest”. These celebrations are derived from evolving stages in a life and signify progression and change. They can be culminated and categorized under traditional classifications of the life cycle rituals, and represent the dynamic growth of society and culture in today's modern and technologically advanced world.
Traditional rites have also been revived and expanded, specifically due to the influence and development of the women's movement demanding equal rights. Geffen states that this has resulted in mothers, as well as fathers, demanding inclusion in birth, adolescent and marriage rituals for themselves and for their sons and daughters. Such practices encourage unity and equality within society. They also shun previously held beliefs of the male sex being dominant and superior, and instead encourage more practices that celebrate the female sex on equal footing.
References
Life cycle ceremonies
Ritual | Life cycle ritual | [
"Biology"
] | 2,348 | [
"Behavior",
"Human behavior",
"Ritual"
] |
60,769,668 | https://en.wikipedia.org/wiki/Shuiyousphaeridium | Shuiyousphaeridium is an extinct genus of acritarch discovered in 1993. Dated to 1.8Ga, it represents one of the earliest fossil eukaryote taxa. It is found in the Changcheng System and the Ruyang Group of China.
References
Acritarch genera | Shuiyousphaeridium | [
"Biology"
] | 61 | [
"Eukaryotes",
"Eukaryote stubs"
] |
62,877,073 | https://en.wikipedia.org/wiki/Hack%20Fall%20Wood | Hack Fall Wood, otherwise known as Hackfall, is a Site of Special Scientific Interest, or SSSI, of , lying north-east of the village of Grewelthorpe, North Yorkshire, England. During the 18th century it was landscaped in the picturesque style by landowner William Aislabie, who created views by engineering streams and pools, planting trees and building follies. J. M. W. Turner and William Sawrey Gilpin painted it, and pictures of it featured on Catherine the Great's 1773 Wedgwood dinner service. Some 19th century writers called it "one of the most beautiful woods in the country."
Following 20th century clear-felling and natural regeneration of trees, the Woodland Trust purchased the property in 1989. The site was designated as an SSSI in the same year. Together with the Hackfall Trust and the Landmark Trust, the Woodland Trust restored footpaths, conserved the remaining follies and managed the wildlife habitat according to its SSSI status.
The woodland supports varied wildlife, including many birds, animals and flowering plants, plus more than 200 species of liverworts and mosses, and two rare creatures: the beetle Platycis minutus and the lemon slug, which lives only in ancient woodland. The site is now listed as a Conservation Area, and as Ancient Semi-Natural Woodland (ASNW). The woodland is open to the public and has many summer visitors, although the only public facility is a car park.
Site history
There is local evidence of earlier settlements in this area. There are prehistoric earthworks at Magdalen Hill, the name Camp Hill suggests a Roman encampment, and the name Grewelthorpe implies Danish settlement. It is possible that the name Hackfall derives simply from haggen, an Old Norse word associated with tree felling, and the fall of water through the Hackfall Gorge.
Hack Fall Wood is a Grade I listed Historic Garden. The listed follies on the site are Mowbray Point Ruin, Mowbray Castle, the Rustic Temple, and Fisher's Hall. Fisher's Hall is dated 1750, and named after William Aislabie's gardener.
Follies
Fisher's Hall
Fisher's Hall was completed in 1750, and is grade II listed. It is built of tufa, and has an octagonal plan and a single storey. It is without a roof, it has a plain eaves band, and is in Gothic style. The building contains a doorway with a pointed moulded arch and pilasters, above which is a dated and initialled tablet. On the other sides are window openings with pointed arches.
Mowbray Castle
Mowbray Castle was also built in about 1750, and is grade II listed. It is in the form of a ruined stone Gothic tower. There are two storeys, an oval plan, and a front of three bays. In the centre is a large opening with a pointed arch, and the flanking wings contain smaller pointed arches with imposts. Above is a floor band, a cross-shaped opening in the middle bay and pointed arches in the outer bays. At the top are the remains of an eaves band and a parapet.
Rustic Temple
The Rustic Temple is grade II listed and is also mid-18th century. It is stone-built and is now a ruin. It has a single storey and an octagonal plan. On the front is an opening, flanked by square openings, all under large lintels. Inside, in the middle of the back wall, is a round-headed niche.
Mowbray Point Ruin
The ruin at Mowbray Point was built as a banqueting hall. It is also mid-18th century and is the only grade II* listed folly in the wood. It is partly ruined, and is built of stone and tufa. The front range has one storey and five bays, the middle three bays projecting under a pediment with a moulded cornice. In the centre is a doorway flanked by windows, all with pointed arches and voussoirs. The outer bays contain rectangular windows. At the rear are three round arches, the middle one tallest, and a domed roof pierced by roundels. Outside these are tunnel vaults with niches.
Other follies
The grotto was constructed as a place to sit and rest, and admire the view of a drop. By the mid-20th century it had almost entirely collapsed, and so it was not listed with the other follies. The walls have since been rebuilt, using rubble from the original building, and a bench set inside them. There are no plans to restore the roof.
Landscaping
In previous centuries the area which is now designated an SSSI was called Hackfall. John Aislabie (1670–1742) of Studley Royal Park, who had been responsible for the formal-style landscaping of Studley Royal and Fountains Abbey, purchased this land in 1731. He bought it for its timber, and perhaps also for its lime kiln, the coal pits near Limehouse Hill, sandstone quarries for repairing Ripon Cathedral, and the sawmill. His son William Aislabie (1700–1781), with an eye to the sublime aesthetic, landscaped the site in a natural, picturesque style with follies, an artificial waterfall, temples and grottoes among the trees, and the kinds of views and glades which were fashionable at the time. Aislabie used the Banqueting House, now known as the Mowbray Point Ruin, to entertain friends, and in the 19th century this became a tea room for tourists, when Hackfall was the property of Lord Ripon and available to those could pay for entry. Mowbray Point may have been designed by Robert Adam, and is now a holiday cottage controlled by the Landmark Trust.
"Nineteenth century writers hailed [Hackfall] as one of the most beautiful woodlands in the country;" J. M. W. Turner and William Sawrey Gilpin painted here. Hackfall is mentioned in William Wordsworth's Guide to the Lakes, and in works by Arthur Young and Reverend Richard Warner. It was pictured on five or six items of Wedgwood's 944-piece Frog dinner service of 1773, made for Catherine the Great.
Hackfall before the felling
Felling
In March 1933 after the National Trust failed to purchase it due to lack of funds, timber merchant John Green bought the wood, and most of it was clear-felled, then partially replanted with conifers. By 1937 Hackfall was a commercial farm and woodland, then during World War II it was allowed to degenerate, and fell prey to vandalism. Some features, including wooden buildings, were lost during the 1930s and 1940s, including cascades, weirs, benches, seats, a pair of summerhouses, and two items called the Sentry Box and the Tent. The wood was, however, allowed to regenerate naturally until the 1980s, and a small part still remains of the Sandbed Hut near Limehouse Hill, and the entrance Gate Pillars.
Restoration
When the property was offered for sale in 1987 and a threat of commercial development was noted, the Hackfall Trust was formed to raise funds for restoration of the landscaping. In 1989 the Woodland Trust purchased it on a 999-year lease, "restoring footpaths and woodland walks, conserving the various follies, managing the fragile habitats."
Almost £1,000,000 was given to the Woodland Trust by the National Lottery Heritage Fund for restoration in 2007. The work was also funded by Yorventure and Nidderdale Area of Outstanding Natural Beauty. The three organisations responsible for organising the restoration and maintenance of the site are the Hackfall Trust, the Woodland Trust and the Landmark Trust. The Landscape Agency carried out the work, and received the Landscape Award in 2008 from RIBA White Rose Awards. A warden was provided for the wood in 2009. The Hackfall and Woodland Trusts were under contract to maintain the woodland until around 2034.
Hack Fall Wood after regeneration
Site location and designation
Hack Fall Wood is a biological Site of Special Scientific Interest (SSSI), designated because "it is important as a largely undisturbed example of ancient semi-natural broadleaved woodland." This "ancient woodland" with its large variety of flora over a mixed geology holds a valued resource of plant life. The key habitat of Hack Fall Wood is listed as a Conservation Area, it is included in the United Kingdom Biodiversity Action Plan (BAP); it is listed as Ancient Semi-Natural Woodland (ASNW), and it is on the Invertebrate Site Register (ISR).
It sits on the north and east slopes where the River Ure flows through the Hackfall Gorge, the site being adjacent to the north-east side of Grewelthorpe, and south of Masham. There are four separate entrances to the site. Although there are no facilities apart from a comparatively recent car park, the site has been popular with tourists since the 19th century. There are no toilets, the nearest being at Grewelthorpe or Masham, and there is no wheelchair access, due to rough terrain and steep paths.
Significant biological content
Flora
This ancient woodland was mostly felled in the 1930s, and the present tree cover has naturally regenerated since then, featuring a diversity of localised species, and also many common species such as sycamore, beech, scots pine, foxglove, dog rose and red campion. Hack Fall Wood is known for its spring carpet of bluebells.
Plants grow here in specific groups according to the underlying geology. For example, around the Brimham Grits cliffs and steep slopes the soil is acidic, and woodland trees are holly, rowan, with a predominant canopy of silver birch and sessile oak. On the woodland floor are small cow-wheat, hard fern, heather, bilberry, wavy hair-grass and great wood-rush.
Under the less steep slopes are Ure Shell beds, and here the soil is less acidic. Among the herbaceous plants are herb Paris and toothwort, which are "uncommon." Other woodland floor plants here are primrose, wood anemone, enchanter's nightshade, woodruff or sweet-scented bedstraw, ramsons or wild garlic and dog's mercury. This ground flora is described by Natural England as "characteristic of old, established woodland." Above these, the understorey contains guelder rose and hazel. Above this is a canopy of sycamore, wych elm and ash. Lesser celandine, early dog violet, opposite-leaved golden-saxifrage (Chrysosplenium oppositifolium) and wood sorrel are also present in spring.
This site has many pools and streams, resulting from "a series of calcareous springs," which "give rise to ... extensive flushing." On the wettest ground is tufted hair-grass, pendulous sedge, great horsetail and meadowsweet, below spindle, bird cherry and alder. Beside the streams, on steep sides and rocks, are many bryophytes, and ferns such as male fern, polypody and hart's tongue.
In the northern part of the site, many wych elms have been lost to Dutch elm disease, leaving clearings full of rose bay willowherb, bramble and bracken. The southern end is more fortunate in having wood fescue (Festuca altissima) "which has a very local distribution in Great Britain." The wood fescue grows on cliff faces above the River Ure. In the woods nearby are many small-leaved lime, some of which has regenerated from 18th century plantings.
Fauna
The site supports a large variety of birds. Beside the river, common sandpiper, grey wagtail, dipper, kingfisher, and even osprey, have been reported. In the woods are lesser spotted woodpecker, green woodpecker, great spotted woodpecker, wood warbler, nuthatch, chiffchaff, treecreeper and buzzard. The Harrogate and District Naturalist's Society (HDNS) recorded 24 bird species here in March 2017, including mallard, sparrowhawk, grey wagtail, wren, robin, song thrush, blackbird, chiffchaff, great tit, long-tailed tit, nuthatch and chaffinch.
Animals seen here are stoat, badger, red fox, brown hare, rabbit, grey squirrel, mole, roe deer, and otter. The noctule bat and pipistrelle are here, besides the common frog, which congregates seasonally at the Fountain Pond. The palmate newt, smooth newt and common toad have been seen here also.
Bryophytes
202 liverworts and mosses have been recorded here, and Harrogate and District Naturalists' Society (HDNS) recorded 24 bryophytes in March 2017, including Pseudotaxiphyllum elegans, Orthotrichum pulchellum, Thamnobryum alopecurum, Mnium hornum, Eurhynchium striatum and Orthotrichum affine.
Other biota
Various butterflies are present, including speckled wood, orange tip and peacock. Also recorded here are the "locally rare" beetle (Platycis minutus) and the lemon slug. The lemon slug is a creature of ancient woodland which eats fungi; it has become rare as a result of loss of habitat.
Maintenance
The main principles of maintenance in this case are to make sure that the woodland is appropriate for the site's history, geology and geography, that it can continue to regenerate following the clearcutting of the 1930s, and that the protected habitat and biota can be supported. This means that there should be old and young trees, and some mature trees with a thick understorey.
Dead wood is good for fungi and invertebrates, but this wood constitutes a public area, so dying trees must be made safe especially in popular places. Invertebrates and butterflies will benefit from occasional lighter man-made clearings; this may require cutting, coppicing or even felling trees. Between August and February (to avoid the breeding season), non-Indigenous trees and shrubs may be cleared, and in some areas thinning may take place to maintain variety of woodland structure. Stump re-growth and natural seed regeneration is preferable to planting, because such natural processes contribute to all woodland life. Light grazing by deer, cattle and rabbits is conducive to species diversity, but sometimes the woodland will need protection from these if they over-graze. Himalayan balsam and rhododendron should be controlled to protect the integrity of the natural woodland. Some areas of the wood should be left completely unmanaged, with fallen trees permitted to pile up, providing habitat and insect food for a variety of wildlife.
Around the calcareous tufa springs, there is specialised plant life. This plant life depends on the minerals from the springs, and the springs depend on protection of the aquifer below. Therefore, the site should be protected against commercial and agricultural water extraction or ground pollution by waste, fertiliser, herbicide and insecticide.
Development and risk assessment
The whole site is covered by upland "broadleaved, mixed and yew woodland," which Natural England has measured out in two large units and one smaller unit. When the site was assessed on 28 May 2012, the first two larger units were judged to be in favourable condition. Unit One, in the north, had mature woodland with old and young trees, fallen deadwood and some sycamore but not too much. Its ground flora met with approval. Unit Two, in the centre of the site, had been in less favourable condition but was now acceptable, with varied woodland, diverse flora and sycamore whose expansion had been cut back sufficiently but still required monitoring. The report mentions issues with previous "scrubbing up of the tufa," which had now been addressed.
The third unit, in the east, was judged "unfavourable, recovering." It was considered mostly acceptable, with "diverse ground flora," and especially wood fescue (Festuca altissima). There was plenty of bilberry above Raven Scar, which was given approval. The unfavourable assessment was due to the overwhelming amount of sycamore. There was too little regeration of plant life other than sycamore. There was no perceived immediate threat to the condition of any part of the site. Harrogate Borough Council's conservation document of 2011 provides full information on the quality of the site and public consultation obligations.
See also
Listed buildings in Grewelthorpe
There are about eight SSSIs in the Harrogate region, others being Bishop Monkton Ings, Brimham Rocks, Cow Myers,
Farnham Mires, Hay-a-Park Gravel Pit, Kirk Deighton Mar Field Fen, Quarry Moor, and Ripon Parks.
Notes
References
External links
(archive images of follies)
(A written description of Hackfall as it was in the mid-19th century)
Sites of Special Scientific Interest in North Yorkshire
Sites of Special Scientific Interest notified in 1989
Landscape architecture
Forests and woodlands of North Yorkshire
Grewelthorpe | Hack Fall Wood | [
"Engineering"
] | 3,578 | [
"Landscape architecture",
"Architecture"
] |
62,877,206 | https://en.wikipedia.org/wiki/Auricular%20splint | An auricular splint (AS) or ear splint is a custom-made medical device that is used to maintain auricular projection and dimensions following second stage auricular reconstruction. The AS is made from ethylene-vinyl acetate (EVA), which is typically used to make custom-made mouthguards and was developed by a team from Great Ormond Street Hospital in the United Kingdom.
History
The auricle is typically reconstructed using autogenous cartilage, which is the most reliable material for producing the best results with the least complications. Cartilage from the knee and contralateral auricular cartilage from the concha have also been reported but costal cartilage is typically used as it is the only donor site that provides sufficient tissue to fabricate the complete auricular framework. The four main elements to consider when assessing the final reconstructed auricle are:
The symmetry of size of the auricle
The projection of the auricle
The adequacy of the temporoauricular sulcus (the depression behind the auricle next to the head)
The contour of the different subunits of the reconstructed auricle
In order to prevent compression during sleep and to prevent the grafted skin from contracting, the use of a Foley catheter, Reston Foam, silicone foam, polysiloxane and
dental impression compound have been described. The auricular splint was developed with the aim of overcoming the drawbacks associated with these methods.
Technique
The auricular splint (AS) is easy to fit and remove, self-retaining, lightweight and easy to camouflage due to its transparency. The AS is made from ethylene-vinyl acetate (EVA), which is inert and non-toxic, non-absorbent, sufficiently elastic to allow it to fitted and removed but sufficiently rigid to avoid breakage.
The concept was first presented at the 2nd Congress of the International Society for Auricular Reconstruction in Beijing, China in September 2017 and published in the Annals of Plastic Surgery the following year.
The first stage involves taking an impression of the reconstructed auricle with Soft Putty Elastomer, which is cast in dental stone to make a model of the reconstructed auricle. The splint is made by thermoforming a 4mm sheet of transparent ethylene-vinyl acetate (EVA) over the stone model. The edges of the splint are trimmed and polished using the outline on the model as a guide.
The splint has been found to maintain auricular projection and other key dimensions up to the six-month post-operative follow-up.
References
2017 in science
2017 introductions
Congenital disorders of ears
Ear
Ear procedures
Ear surgery
Medical devices
Plastic surgery | Auricular splint | [
"Biology"
] | 571 | [
"Medical devices",
"Medical technology"
] |
62,878,887 | https://en.wikipedia.org/wiki/Curvature%20renormalization%20group%20method | In theoretical physics, the curvature renormalization group (CRG) method is an analytical approach to determine the phase boundaries and the critical behavior of topological systems. Topological phases are phases of matter that appear in certain quantum mechanical systems at zero temperature because of a robust degeneracy in the ground-state wave function. They are called topological because they can be described by different (discrete) values of a nonlocal topological invariant. This is to contrast with non-topological phases of matter (e.g. ferromagnetism) that can be described by different values of a local order parameter. States with different values of the topological invariant cannot change into each other without a phase transition. The topological invariant is constructed from a curvature function that can be calculated from the bulk Hamiltonian of the system. At the phase transition, the curvature function diverges, and the topological invariant correspondingly jumps abruptly from one value to another. The CRG method works by detecting the divergence in the curvature function, and thus determining the boundaries between different topological phases. Furthermore, from the divergence of the curvature function, it extracts scaling laws that describe the critical behavior, i.e. how different quantities (such as susceptibility or correlation length) behave as the topological phase transition is approached. The CRG method has been successfully applied to a variety of static, periodically driven, weakly and strongly interacting systems to classify the nature of the corresponding topological phase transitions.
Background
Topological phases are quantum phases of matter that are characterized by robust ground state degeneracy and quantized geometric phases. Transitions between different topological phases are usually called topological phase transitions, which are characterized by discrete jumps of the topological invariant . Upon tuning one or multiple system parameters , jumps abruptly from one integer to another at the critical point . Typically, the topological invariant takes the form of an integration of a curvature function in momentum space:Depending on the dimensionality and symmetries of the system, the curvature function can be a Berry connection, a Berry curvature, or a more complicated object.
In the vicinity of high symmetry points in a -dimensional momentum space, where is a reciprocal lattice vector, the curvature function typically displays a Lorentzian shape
where defines the width of the multidimensional peak. Approaching the critical point the peak gradually diverges, flipping sign across the transition:This behavior is displayed in the video on the side for the case .
Scaling laws, critical exponents, and universality
The divergence of the curvature function permits the definition of critical exponents as The conservation of the topological invariant , as the transition is approached from one side or the other, yields a scaling law that constraints the exponents where is the dimensionality of the problem. These exponents serve to classify topological phase transitions into different universality classes.
To experimentally measure the critical exponents, one needs to have access to the curvature function with a certain level of accuracy. Good candidates at present are quantum engineered photonics and ultracold atomic systems. In the first case, the curvature function can be extracted from the anomalous displacement of wave packets under optical pulse pumping in coupled fibre loops. For ultracold atoms in optical lattices, the Berry curvature can be achieved through quantum interference or force-induced wave-packet velocity measurements.
Correlation function
The Fourier transform of the curvature function typically measures the overlap of certain quantum mechanical wave functions or more complicated objects, and therefore it is interpreted as a correlation function. For instance, if the curvature function is the noninteracting or many-body Berry connection or Berry curvature, the correlation function is a measure of the overlap of Wannier functions centered at two home cells that are distance apart. Because of the Lorentzian shape of the curvature function mentioned above, the Fourier transform of the curvature function decays with the length scale . Hence, is interpreted as the correlation length, and its critical exponent is assigned to be like in Landau theory. Furthermore, the correlation length is related to the localization length of topological edge states, such as Majorana modes.
Scaling equation
The scaling procedure that identifies the topological phase transitions is based on the divergence of the curvature function. It is an iterative procedure that, for a given parameter set that controls the topology, searches for a new parameter set that satisfies where is a high-symmetry point and is a small deviation away from it. This procedure searches for the path in the parameter space of along which the divergence of the curvature function reduces, yielding a renormalization group flow that flows away from the topological phase transitions. The name "curvature renormalization group" is derived precisely from this procedure that renormalizes the profile of the curvature function. Writing and , and expanding the scaling equation above to leading order yields the generic renormalization group equation
The renormalization group flow can be obtained directly as a stream plot of the right hand side of this differential equation. Numerically, this differential equation only requires the evaluation of the curvature function at few momenta. Hence, the method is a very efficient way to identify topological phase transitions, especially in periodically driven systems (aka Floquet systems) and interacting systems.
See also
Topological quantum number
Berry connection and curvature
Topological insulator
Periodic table of topological invariants
Dirac matter
Landau theory
Critical exponent
Scaling law
Correlation function (statistical mechanics)
Universality (dynamical systems)
Renormalization group
Floquet theory
Majorana fermion
Surface states
References
Theoretical physics | Curvature renormalization group method | [
"Physics"
] | 1,106 | [
"Theoretical physics"
] |
62,879,352 | https://en.wikipedia.org/wiki/IRAS%2013224-3809 | IRAS 13224-3809 is a highly active and fluctuating Seyfert 1 galaxy in the constellation Centaurus about 1 billion light-years from Earth. The galaxy is notable due to its centrally-located supermassive black hole that is closely studied by astronomers using x-ray astronomy, particularly X-ray reverberation echo mapping techniques, in an effort to better understand the inner workings, including mass and spin, of black holes.
References
External links
SIMBAD
SIMBAD/ascii
Centaurus
Seyfert galaxies
TIC objects
088835
2MASS objects | IRAS 13224-3809 | [
"Astronomy"
] | 124 | [
"Galaxy stubs",
"Centaurus",
"Astronomy stubs",
"Constellations"
] |
62,881,422 | https://en.wikipedia.org/wiki/Transverse-field%20Ising%20model | The transverse field Ising model is a quantum version of the classical Ising model. It features a lattice with nearest neighbour interactions determined by the alignment or anti-alignment of spin projections along the axis, as well as an external magnetic field perpendicular to the axis (without loss of generality, along the axis) which creates an energetic bias for one x-axis spin direction over the other.
An important feature of this setup is that, in a quantum sense, the spin projection along the axis and the spin projection along the axis are not commuting observable quantities. That is, they cannot both be observed simultaneously. This means classical statistical mechanics cannot describe this model, and a quantum treatment is needed.
Specifically, the model has the following quantum Hamiltonian:
Here, the subscripts refer to lattice sites, and the sum is done over pairs of nearest neighbour sites and . and are representations of elements of the spin algebra (Pauli matrices, in the case of spin 1/2) acting on the spin variables of the corresponding sites. They anti-commute with each other if on the same site and commute with each other if on different sites. is a prefactor with dimensions of energy, and is another coupling coefficient that determines the relative strength of the external field compared to the nearest neighbour interaction.
Phases of the 1D transverse field Ising model
Below the discussion is restricted to the one dimensional case where each lattice site is a two-dimensional complex Hilbert space (i.e., it represents a spin 1/2 particle). For simplicity here and are normalised to each have determinant -1. The Hamiltonian possesses a symmetry group, as it is invariant under the unitary operation of flipping all of the spins in the direction. More precisely, the symmetry transformation is given by the unitary .
The 1D model admits two phases, depending on whether the ground state (specifically, in the case of degeneracy, a ground state which is not a macroscopically entangled state) breaks or preserves the aforementioned spin-flip symmetry. The sign of does not impact the dynamics, as the system with positive can be mapped into the system with negative by performing a rotation around for every second site .
The model can be exactly solved for all coupling constants. However, in terms of on-site spins the solution is generally very inconvenient to write down explicitly in terms of the spin variables. It is more convenient to write the solution explicitly in terms of fermionic variables defined by Jordan-Wigner transformation, in which case the excited states have a simple quasiparticle or quasihole description.
Ordered phase
When , the system is said to be in the ordered phase. In this phase the ground state breaks the spin-flip symmetry. Thus, the ground state is in fact two-fold degenerate. For this phase exhibits ferromagnetic ordering, while for antiferromagnetic ordering exists.
Precisely, if is a ground state of the Hamiltonian, then is also a ground state, and together and span the degenerate ground state space. As a simple example, when and , the ground states are and , that is, with all the spins aligned along the axis.
This is a gapped phase, meaning that the lowest energy excited state(s) have an energy higher than the ground state energy by a nonzero amount (nonvanishing in the thermodynamic limit). In particular, this energy gap is .
Disordered phase
In contrast, when , the system is said to be in the disordered phase. The ground state preserves the spin-flip symmetry, and is nondegenerate. As a simple example, when is infinity, the ground state is , that is with the spin in the direction on each site.
This is also a gapped phase. The energy gap is .
Gapless phase
When , the system undergoes a quantum phase transition. At this value of , the system has gapless excitations and its low-energy behaviour is described by the two-dimensional Ising conformal field theory. This conformal theory has central charge , and is the simplest of the unitary minimal models with central charge less than 1. Besides the identity operator, the theory has two primary fields, one with conformal weights and another one with conformal weights .
Jordan-Wigner transformation
It is possible to rewrite the spin variables as fermionic variables, using a highly nonlocal transformation known as the Jordan-Wigner Transformation.
A fermion creation operator on site can be defined as . Then the transverse field Ising Hamiltonian (assuming an infinite chain and ignoring boundary effects) can be expressed entirely as a sum of local quadratic terms containing Creation and annihilation operators. This Hamiltonian fails to conserve total fermion number and does not have the associated global continuous symmetry, due to the presence of the term. However, it does conserve fermion parity. That is, the Hamiltonian commutes with the quantum operator that indicates whether the total number of fermions is even or odd, and this parity does not change under time evolution of the system. The Hamiltonian is mathematically identical to that of a superconductor in the mean field Bogoliubov-de Gennes formalism and can be completely understood in the same standard way. The exact excitation spectrum and eigenvalues can be determined by Fourier transforming into momentum space and diagonalising the Hamiltonian.
In terms of Majorana fermions and , the Hamiltonian takes on an even simpler form (up to an additive constant): .
Kramers-Wannier duality
A nonlocal mapping of Pauli matrices known as the Kramers–Wannier duality transformation can be done as follows:
Then, in terms of the newly defined Pauli matrices with tildes, which obey the same algebraic relations as the original Pauli matrices, the Hamiltonian is simply . This indicates that the model with coupling parameter is dual to the model with coupling parameter , and establishes a duality between the ordered phase and the disordered phase. In terms of the Majorana fermions mentioned above, this duality is more obviously manifested in the trivial relabeling .
Note that there are some subtle considerations at the boundaries of the Ising chain; as a result of these, the degeneracy and symmetry properties of the ordered and disordered phases are changed under the Kramers-Wannier duality.
Generalisations
The q-state quantum Potts model and the quantum clock model are generalisations of the transverse field Ising model to lattice systems with states per site. The transverse field Ising model represents the case where .
Classical Ising Model
The quantum transverse field Ising model in dimensions is dual to an anisotropic classical Ising model in dimensions.
References
Lattice models
Spin models
Quantum models | Transverse-field Ising model | [
"Physics",
"Materials_science"
] | 1,400 | [
"Spin models",
"Quantum mechanics",
"Lattice models",
"Computational physics",
"Quantum models",
"Condensed matter physics",
"Statistical mechanics"
] |
62,881,629 | https://en.wikipedia.org/wiki/Amide%20%28functional%20group%29 | In chemistry, the term amide ( or or ) is a compound with the functional group RnE(=O)xNR2, where x is not zero, E is some element, and each R represents an organic group or hydrogen. It is a derivative of an oxoacid RnE(=O)xOH with an hydroxy group –OH replaced by an amine group –NR2.
Some important subclasses are
carboxamides, or organic amides, where E = carbon, with the general formula RC(=O)NR2.
phosphoramides, where E = phosphorus, such as R2P(=O)NR2
sulfonamides, where E = sulfur, namely RS(=O)2NR2
The term amide may also refer to
amide group, a functional group –C(=O)N= consisting of a carbonyl adjacent to a nitrogen atom.
cyclic amide or lactam, a cyclic compound with the amide group –C(=O)N– in the ring.
metal amide, an ionic compound ("salt") with the azanide anion H2N− (the conjugate base of ammonia) or to a derivative thereof R2N−.
There is also a neutral amino radical (•NH2) and a positively charged NH2+ ion called a nitrenium ion, but both of these are very unstable.
See also
Imide
References | Amide (functional group) | [
"Chemistry"
] | 304 | [
"Amides",
"Functional groups"
] |
62,881,760 | https://en.wikipedia.org/wiki/Lactarius%20albocarneus | Lactarius albocarneus is a member of the large genus Lactarius (order Russulales), known as milk-caps. Found in Europe, the species was first described in 1895 by German mycologist Max Britzelmayr.
See also
List of Lactarius species
References
albocarneus
Fungi of Europe
Fungi described in 1895
Taxa named by Max Britzelmayr
Fungus species | Lactarius albocarneus | [
"Biology"
] | 86 | [
"Fungi",
"Fungus species"
] |
62,882,118 | https://en.wikipedia.org/wiki/Dynamic%20revetment | Dynamic revetments, also known as "cobble berms" or "dynamic cobble berm revetments", use gravel or cobble-sized rocks to mimic a natural cobble storm beach for the purpose of reducing wave energy and stopping or slowing coastal erosion.
Unlike seawalls, dynamic revetment is designed to allow wave action to rearrange the stones into an equilibrium profile, disrupting wave action and dissipating wave energy as the cobbles move. This can reduce the wave reflection which often contributes to beach scouring.
Principle
The goal is to create structures that are natural in appearance and function while providing acceptable protection to coastlines, combining the benefits of ecologically responsive shore protection methods with those of conventional armor‑stone revetments or seawalls.
A line of logs can also be employed as upper reinforcement for a cobble berm. Drift logs are common on most shores in the Pacific Northwest. Their crisscrossed arrangement provides dynamic stability even when impacted by high tides and waves, capturing wind-blown sand and encouraging the growth of foredunes.
History
Self-protection via landslides was demonstrated in the early 1990s when, in an effort to stabilize the Lone Tree landslide 15 km north of San Francisco, California Department of Transportation dumped excavated material including rocks and sediment sized from clay to large boulders down a steep cliff face, creating an artificial landslide. This experiment permitted the documentation of the early stages of landslide erosion, including the processes of waves cutting away the toe of the slide. It was observed that a beach immediately began to form along the toe of the eroding slide, consisting of the coarsest materials, gravel, cobbles and boulders. With its accumulation, the rate of toe erosion progressively slowed, the material having sorted itself into a protective gravel and cobble beach, backed in riprap-like fashion by a line of armor-sized boulders.
Laboratory experiment
In 2017 DynaRev, a research project funded by the European Union, conducted a large scale laboratory experiment at the Large Wave Flume (Großer Wellenkanal) in Hanover, Germany. Its aim was to determine the performance and resilience of dynamic revetments to rising sea-level. The response of a sand beach was measured for various water levels and wave heights, both with and without an upper cobble berm. During the experiment, the dynamic revetment demonstrated dynamic stability, as the individual cobbles within the structure moved with every wave but the global shape of the revetment remained stable. The researchers determined that dynamic revetments appeared to be a sustainable and affordable option for many locations experiencing coastal erosion where complete protection from coastal hazards is not needed and some coastal retreat is acceptable.
Projects
Surfer's Point, Ventura, California
In 2011, the Surfers' Point working group relocated the bike path and parking lot. To stabilize the area the project constructed a "cobble mattress" on the back beach. Sand was placed in the retreat zone to complement the cobbles and help rebuild the dunes. Later, the project constructed dunes using sand sourced from other beaches with excess sand. The project used grant funds from the California Coastal Conservancy and the Federal Highway Administration.
Cape Lookout State Park, Oregon
Following storm damage to Cape Lookout State Park in 1999, some form of shore protection was sought. A conventional riprap revetment or seawall was deemed incompatible with this natural park setting, so the decision was made to construct a cobble berm that resembled the appearance and function of a natural cobble beach, backed by an artificial foredune that was reinforced by a core of sand-filled geotextile bags. Oregon Parks and Recreation Department completed construction of the 300-m long project by December 2000.
State Route 105, North Cove, Washington
In 1996 a rock jetty was constructed to protect State Route 105 near North Cove, which appeared to increase the erosion to the east by redirecting the force of the waves. In response, Washington State Department of Transportation constructed 780 feet of dynamic revetment along the south side of the highway right of way in the fall of 2017. The revetment generally performed as intended, with storm erosion transporting the berm material to the toe where it can buffer and dissipate wave energy. However, due to project footprint constraints, the cobble berm was constructed with a narrow width at the western end where wave energy is highest. This segment receives the brunt of waves that refract off adjacent riprap along the highway. Cobble re-nourishment was required several times during the first winter.
North Cove Community, North Cove, Washington
In 2016, as a response to what has been called the fastest erosion on the West Coast of the United States, the community of North Cove began placing unsorted pit-run basalt of predominantly cobble size along nearly 2 miles of shoreline to slow the erosion while engineers worked on a more permanent design. The community nonprofit group Wash Away No More supported the project through fundraising and work parties. Working with regulatory agencies, the principles of Adaptive management and Design with Nature were incorporated into the project to allow for learning and change based on periodic monitoring by Washington State Department of Ecology. As part of the monitoring, PIT tags were placed in individual rocks and their motion tracked over time. It was observed that the rocks that moved farthest weighed between 1 and 10 kg (2.2 and 22 lb) with an intermediate axis of about 10 to 20 cm (4 to 8 in). Angular and rounded rocks appeared to perform equivalently in this environment. Technical assistance and funding were provided by the Pacific County Conservation District. The lost beach quickly returned.
As Chairman of Pacific County Drainage District #1 and with support from Wash Away No More and the Pacific Conservation District, local cranberry farmer David Cottrell led the project through all phases from conception, construction, and adaptive management between 2016 and 2023. David undertook significant hands-on work alongside the local community to ensure cobble levels were maintained and carried out pioneering experiments on how and where to place cobble volume and the use of local driftwood to enhance coastal protection. This work drew the attention of coastal engineering academics in the USA and internationally, and David co-authored several papers on the topic of dynamic revetments.
See also
Shingle beach
Storm beach
References
Marine revetments
Coastal construction
Coastal engineering
Coastal erosion | Dynamic revetment | [
"Engineering"
] | 1,298 | [
"Construction",
"Coastal engineering",
"Coastal construction",
"Civil engineering"
] |
62,883,325 | https://en.wikipedia.org/wiki/Color%20Developing%20Agent%202 | Color Developing Agent 2 is the second in the series of color developing agents used in developing color films. It is commonly known as CD-2 and is chemically known as 4-diethylamino-o-toluidine, 1,4-benzenediamine, N4,N4-diethyl-2-methyl-, N1,N1-diethyl-3-methylbenzene-1,4-diamine, or 4-(diethylamino)-2-methylaniline. In color development, after reducing a silver atom in a silver halide crystal, the oxidized developing agent combines with a color coupler to form a color dye molecule.
See also
Color Developing Agent 1
Color Developing Agent 3
Color Developing Agent 4
References
Photographic chemicals
Anilines | Color Developing Agent 2 | [
"Chemistry"
] | 167 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
62,884,268 | https://en.wikipedia.org/wiki/S62%20%28star%29 | S62 is a star in the cluster surrounding Sagittarius A* (Sgr A*), the supermassive black hole in the center of the Milky Way. S62 was initially thought to orbit extremely close to Sgr A*, with a period of 9.9 years and a closest approach of only , less than the distance between Uranus and the Sun. This would have put it at just 215 times the Schwarzschild radius of Sgr A* (the Schwarzschild radius of Sgr A* is approximately 0.082 AU, or 12 million km).
However, later observations with the GRAVITY instrument of the Very Large Telescope observed S62 to be in an inconsistent position compared to the prediction from the original observations. The star was observed to be moving linearly, with no detected acceleration, indicating that it not as close to the black hole as it appears in projection. The original, mistaken orbital reconstruction is consistent with an observation of the star S29 having been mistaken for S62.
References
Sagittarius (constellation)
Galactic Center | S62 (star) | [
"Astronomy"
] | 224 | [
"Sagittarius (constellation)",
"Constellations"
] |
62,884,556 | https://en.wikipedia.org/wiki/Combined%20diesel-electric%20and%20diesel | Combined diesel-electric and diesel (CODLAD) is a naval propulsion system in which an electric motor and a diesel engine act on a single propeller. The transmission system takes care of making one or both motors act on the propeller shaft.
Description
The CODLAD propulsion system is based on the use of electric motors directly connected to the axes (generally two) of the propellers. The electric motors are powered by diesel generators and to have higher speeds, as happens in CODAD propulsion systems, the higher power diesel engine is inserted which is disconnected from the transmission system to return to cruising speed.
This system that uses diesel engines for both propulsion and for the production of electricity for on-board services significantly reduces costs, as the number of diesel engines for the various ship services decreases and the electric motors need less maintenance. Furthermore, since electric motors can work more effectively in a larger number of revolutions, and being directly connected to the propeller axis, the transmission systems for coupling and decoupling the diesel-electric systems with the diesel engines used to have higher speeds.
The CODLAD system has been adopted in the new Vulcano-class logistic support ship under construction for the Italian Navy.
References
Marine propulsion
Diesel engine technology | Combined diesel-electric and diesel | [
"Engineering"
] | 242 | [
"Marine propulsion",
"Marine engineering"
] |
62,885,083 | https://en.wikipedia.org/wiki/Color%20Developing%20Agent%201 | Color Developing Agent 1 (CD-1) is the first in the series of color developing agents used in developing color films. It is the organic compound N,N-diethyl-1,4-benzenediamine (DPD), which is usually in the form of the monohydrochloride salt. In color development, after reducing a silver atom in a silver halide crystal, the oxidized developing agent combines with a color coupler to form a color dye molecule.
Arthur Thomas Palin, a Fellow of the Royal Society of Chemistry, developed a widely used color based method of water testing using DPD to indicate the chlorine content of treated water.
See also
Color Developing Agent 2
Color Developing Agent 3
Color Developing Agent 4
References
Photographic chemicals
4-Aminophenyl compounds
Diethylamino compounds | Color Developing Agent 1 | [
"Chemistry"
] | 170 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
62,885,320 | https://en.wikipedia.org/wiki/Vir%20Bahadur%20Singh%20Planetarium%2C%20Gorakhpur | Vir Bahadur Singh Planetarium (also spelled 'Veer' or 'Bir') is a tourist attraction in Gorakhpur, Uttar Pradesh, India. It has been run by the Council of Science & Technology, Uttar Pradesh since 21 December 2009.
This planetarium runs three daily, 45-minute shows at 1pm, 3pm and 5pm. It has a dome size of 18m and a seating capacity of 395. It is based on digital technology, and six equipments of CRT, Evans and Sutherland are installed here.
See also
Astrotourism in India
List of planetariums
References
See also
List of planetariums
Planetaria in India
Tourist attractions in Gorakhpur
Buildings and structures in Gorakhpur | Vir Bahadur Singh Planetarium, Gorakhpur | [
"Astronomy"
] | 149 | [
"Astronomy stubs"
] |
62,886,564 | https://en.wikipedia.org/wiki/List%20of%20mechanical%20engineering%20awards | This list of mechanical engineering awards is an index to articles about notable awards for mechanical engineering.
Awards
See also
Lists of awards
Lists of science and technology awards
List of engineering awards
References
Mechanical engineering | List of mechanical engineering awards | [
"Technology",
"Engineering"
] | 39 | [
"Science and technology awards",
"Mechanical engineering awards",
"Mechanical engineering",
"Lists of science and technology awards"
] |
44,307,291 | https://en.wikipedia.org/wiki/Chemical%20reaction%20model | Chemical reaction models transform physical knowledge into a mathematical formulation that can be utilized in computational simulation of practical problems in chemical engineering. Computer simulation provides the flexibility to study chemical processes under a wide range of conditions. Modeling of a chemical reaction involves solving conservation equations describing convection, diffusion, and reaction source for each component species.
Species transport equation
Ri is the net rate of production of species i by chemical reaction and Si is the rate of creation by addition from the dispersed phase and the user defined source. Ji is the diffusion flux of species i, which arises due to concentration gradients and differs in both laminar and turbulent flows. In turbulent flows, computational fluid dynamics also considers the effects of turbulent diffusivity. The net source of chemical species i due to reaction, Ri which appeared as the source term in the species transport equation is computed as the sum of the reaction sources over the NR reactions among the species.
Reaction models
These reaction rates R can be calculated by following models:
Laminar finite rate model
Eddy dissipation model
Eddy dissipation concept
Laminar finite rate model
The laminar finite rate model computes the chemical source terms using the Arrhenius expressions and ignores turbulence fluctuations. This model provides with the exact solution for laminar flames but gives inaccurate solution for turbulent flames, in which turbulence highly affects the chemistry reaction rates, due to highly non-linear Arrhenius chemical kinetics. However this model may be accurate for combustion with small turbulence fluctuations, for example supersonic flames.
Eddy dissipation model
The eddy dissipation model or the Magnussen model, based on the work of Magnussen and Hjertager, is a turbulent-chemistry reaction model. Most fuels are fast burning and the overall rate of reaction is controlled by turbulence mixing. In the non-premixed flames, turbulence slowly mixes the fuel and oxidizer into the reaction zones where they burn quickly. In premixed flames the turbulence slowly mixes cold reactants and hot products into the reaction zones where reaction occurs rapidly. In such cases the combustion is said to be mixing-limited, and the complex and often unknown chemical kinetics can be safely neglected. In this model, the chemical reaction is governed by large eddy mixing time scale. Combustion initiates whenever there is turbulence present in the flow. It does not need an ignition source to initiate the combustion. This type of model is valid for the non-premixed combustion, but for the premixed flames the reactant is assumed to burn at the moment it enters the computation model, which is a shortcoming of this model as in practice the reactant needs some time to get to the ignition temperature to initiate the combustion.
Eddy dissipation concept
The eddy dissipation concept (EDC) model is an extension of the eddy dissipation model to include detailed chemical mechanism in turbulent flows. The EDC model attempts to incorporate the significance of fine structures in a turbulent reacting flow in which combustion is important. EDC has been proven efficient without the need for changing the constants for a great variety of premixed and diffusion controlled combustion problems, both where the chemical kinetics is faster than the overall fine structure mixing as well as in cases where the chemical kinetics has a dominating influence.
References
Ansys Fluent Help, Chapters 7, 8.
Henk Kaarle Versteeg, Weeratunge Malalasekera. An Introduction to Computational Fluid Dynamics: The Finite Volume Method.
Magnussen, B. F. & B. H. Hjertager (1977). "On Mathematical Models of Turbulent Combustion with Special Emphasis on Soot Formation and Combustion". Symposium (International) on Combustion. 16 (1): 719–729. doi:10.1016/S0082-0784(77)80366-4.
Bjørn F. Magnussen. Norwegian University of Science and Technology Trondheim (Norway), Computational Industry Technologies AS (ComputIT), The Eddy Dissipation Concept: A Bridge Between Science and Technology.
Schlögl, Friedrich. "Chemical reaction models for non-equilibrium phase transitions." Zeitschrift für Physik 253.2 (1972): 147–161.
Levenspiel, Octave. Chemical reaction engineering. Vol. 2. New York etc.: Wiley, 1972.
Chemical reaction engineering
Mathematical modeling | Chemical reaction model | [
"Chemistry",
"Mathematics",
"Engineering"
] | 902 | [
"Chemical engineering",
"Applied mathematics",
"Chemical reaction engineering",
"Mathematical modeling"
] |
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