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56,415,676 | https://en.wikipedia.org/wiki/WolfSSH | wolfSSH is a small, portable, embedded SSH library targeted for use by embedded systems developers. It is an open-source implementation of SSH written in the C language. It includes SSH client libraries and an SSH server implementation. It allows for password and public key authentication.
Platforms
wolfSSH is currently available for Win32/64, Linux, macOS, Solaris, Threadx, VxWorks, FreeBSD, NetBSD, OpenBSD, embedded Linux, WinCE, Haiku, OpenWrt, iPhone (iOS), Android, Wii and GameCube through DevKitPro support, QNX, MontaVista, TRON variants (TRON/ITRON/μITRON), NonStop OS, OpenCL, Micrium's MicroC/OS-II, FreeRTOS, SafeRTOS, Freescale MQX, Nucleus, TinyOS, TI-RTOS, HP-UX, uTasker, embOS, PIC32, PikeOS, and Green Hills INTEGRITY.
Protocols
The wolfSSH SSH library implements the SSHv2 protocol for both client and server. It also includes support for the Secure copy and SSH File Transfer protocols.
Algorithms
wolfSSH uses the cryptographic services provided by wolfCrypt. wolfCrypt Provides RSA, ECC, Diffie–Hellman, AES (CBC, GCM), Random Number Generation, Large Integer support, and base 16/64 encoding/decoding.
Key exchange
diffie-hellman-group1-sha1
diffie-hellman-group14-sha1
diffie-hellman-group-exchange-sha256
ecdh-sha2-nistp256
ecdh-sha2-nistp384
ecdh-sha2-nistp521
Public key
ssh-rsa
ecdsa-sha2-nistp256
ecdsa-sha2-nistp384
ecdsa-sha2-nistp521
Integrity
hmac-sha1
hmac-sha1-96
hmac-sha2-256
Encryption
aes128-cbc
aes128-gcm (OpenSSH compatible)
Licensing
wolfSSH is open source and dual licensed under both the GNU GPL-3.0-or-later and commercial licensing.
See also
Secure Shell
OpenSSH
DropBear
Comparison of SSH clients
Comparison of SSH servers
Comparison of cryptography libraries
References
External links
wolfSSH Homepage
C (programming language) libraries
Cryptographic software
Secure Shell | WolfSSH | [
"Mathematics"
] | 536 | [
"Cryptographic software",
"Mathematical software"
] |
56,416,473 | https://en.wikipedia.org/wiki/Sulfamoyl%20fluoride | In organic chemistry, sulfamoyl fluoride is an organic compound having the chemical formula F−SO2−N(−R1)−R2. Its derivatives are called sulfamoyl fluorides.
Examples of sulfamoyl fluorides include:
Sulfamoyl fluorides are contrasted with the sulfonimidoyl fluorides with structure R1-S(O)(F)=N-R2.
Production
Sulfamoyl fluorides can be made by treating secondary amines with sulfuryl fluoride (SO2F2) or sulfuryl chloride fluoride (SO2ClF). Cyclic secondary amines work as well, provided they are not aromatic.
Sulfamoyl fluorides can also be made from sulfamoyl chlorides, by reacting with a substance that can supply the fluoride ion, such as NaF, KF, HF, or SbF3.
Sulfonamides can undergo a Hofmann rearrangement when treated with a difluoro-λ3-bromane to yield a singly substituted N-sulfamoyl fluoride.
See also
Fluorosulfonate
Sulfonyl halide
Sulfuryl fluoride
References
Functional groups
Leaving groups | Sulfamoyl fluoride | [
"Chemistry"
] | 269 | [
"Functional groups",
"Organic chemistry stubs",
"Leaving groups"
] |
56,417,022 | https://en.wikipedia.org/wiki/Abell%203742 | Abell 3742 is a galaxy cluster located around 200 million light-years (61 Mpc) from Earth in the constellation Indus. The cluster's brightest member is the elliptical galaxy NGC 7014. Abell 3742 is located in the Pavo–Indus Supercluster and is one of three major clusters along with Abell 3656 and Abell 3698.
See also
Abell catalogue
List of Abell clusters
Galaxy cluster
References
Indus (constellation)
Galaxy clusters
Pavo-Indus Supercluster
3742
Abell richness class 0 | Abell 3742 | [
"Astronomy"
] | 114 | [
"Indus (constellation)",
"Galaxy clusters",
"Astronomical objects",
"Constellations"
] |
77,819,408 | https://en.wikipedia.org/wiki/Camlipixant | Camlipixant is an investigational new drug that is being evaluated for the treatment of chronic cough. It is a P2X3 receptor antagonist.
See also
gefapixant
References
Benzamides
Carbamates
Morpholines
Imidazopyridines | Camlipixant | [
"Chemistry"
] | 57 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
77,820,866 | https://en.wikipedia.org/wiki/Cenerimod | Cenerimod is an investigational new drug that is being evaluated for the treatment of systemic lupus erythematosus. It is a sphingosine-1-phosphate receptor modulator.
References
Glycerols
Oxadiazoles
Pyridines
Cyclopentyl compounds
Ethyl compounds
Methoxy compounds | Cenerimod | [
"Chemistry"
] | 70 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
77,821,098 | https://en.wikipedia.org/wiki/Ceralasertib | Ceralasertib is an investigational new drug that is being evaluated for the treatment of cancer. It is an ATR kinase inhibitor.
References
Cyclopropanes
Morpholines
Pyrimidines
Pyrrolopyridines
Sulfoximines | Ceralasertib | [
"Chemistry"
] | 59 | [
"Pharmacology",
"Sulfoximines",
"Functional groups",
"Medicinal chemistry stubs",
"Pharmacology stubs"
] |
77,821,288 | https://en.wikipedia.org/wiki/Raphael%20M.%20Littauer | Raphael Max Littauer' (* November 28, 1925 †– October 19, 2009) was an American physicist who was a longtime Professor of Physics and Nuclear Studies at Cornell University. He was involved in the development of several particle accelerators there, in particular the 10 GeV electron synchrotron at the Wilson Synchrotron Lab in the late 1960s, where he devised a distributed, multiplexed control system for it, and the Cornell Electron Storage Ring (CESR) in the late 1970s and early 1980s, where his scheme to create pretzel-shaped orbits to increase the number of particle bunches in circulation contributed significantly to CESR having the highest luminosity of any accelerator of its era. Littauer was also known for his teaching, including the design, implementation, and installation of one of the earliest and most successful classroom response systems. An active opponent of the Vietnam War, he led a group at Cornell that published a well-regarded study on the nature and effects of the U.S. air attacks in Southeast Asia. In 1991 he became a Fellow of the American Physical Society and in 1995 he received the Robert R. Wilson Prize for Achievement in the Physics of Particle Accelerators.
Early life and education
Littauer was born in Leipzig, Germany, on November 28, 1925. In March 1939 he emigrated to the United Kingdom, six months before the outbreak of World War II. According to what his daughter later related, he was part of the Kindertransport and was taken in by a family in England.
He attended the University of Cambridge beginning in 1943. He first received an M.A. degree, that being awarded in 1946. He then earned a Ph.D. from Christ's College at Cambridge in 1950, the title of his dissertation being Levels in Light Elements. During this time he worked as an assistant in the famed Cavendish Laboratory.
Marriage and family
Littauer married Salome Alexandra Kroch in 1950. Also born in Leipzig, she and her two sisters had endured a hazardous journey through Europe in order to survive the Holocaust.
Littauer left England for the United States in 1950, becoming a research associate at Cornell University. Together he and his wife had two children. The couple lived in Ithaca, New York. Alexandra Littauer taught French in the younger grades of the Ithaca City School District and later became an instructor in French at Cornell.
Raphael Littauer became a United States citizen in 1956.
Career as physicist
Accelerators and positions
Littauer's arrival at Cornell in 1950 was in order to do work on an electron accelerator at Cornell's Laboratory for Nuclear Studies, which had been founded after World War II by scientists returning to academic life following their efforts at Los Alamos. The director of that laboratory, Robert R. Wilson, was instrumental in bringing Littauer there. At the time Cornell had a 300 MeV electron synchrotron, which was followed in 1952 by a new 1.3 GeV synchrotron.
In 1954, Littauer departed Cornell to work on a synchrotron at the General Electric Research Laboratory in Schenectady, New York. But in 1955, Littauer returned to Cornell for good, being appointed a member of the faculty as a Research Associate Professor of Physics. Once again, Wilson played a role in his return.
In 1963, Littauer was named a research professor. Then in 1965, he became a full professor, being named a professor of Physics and Nuclear Studies.
Littauer was awarded two postdoctoral fellowships from the National Science Foundation. The second of these, in 1968, involved work at the Laboratori Nazionali di Frascati in Italy. There he spent a semester working on the laboratory's new 1.5 GeV electron-positron colliding beam accelerator.
Later in 1968, Cornell's Wilson Synchrotron Laboratory saw the dedication of its new 10 GeV electron synchrotron, the largest and most powerful such one in the world, with Littauer highlighted as one of the people who helped develop it. The ring was built underneath Schoellkopf Field and other athletic facilities on campus. Among Littauer's responsibilities were monitoring and adjusting the steering coils located around the synchrotron's ring . As part of his work, Littauer created a time-sharing, distributed, multiplex control system for the synchrotron that helped reduce both the initial and ongoing costs of the system.
The Cornell Electron Storage Ring (CESR) came into operation at the end of 1970s but initially featured disappointing luminosity, so over the next several years several improvements to it were made. One of them, put into place in 1983, was Littauer's development of a scheme for so-called "pretzel orbits" (a name he came up with). This involved having multiple bunches of particles in a storage ring, but introducing electrostatic separators at key places in the ring such that two counter-circulating beams are displaced in eccentric and opposite directions, thereby limiting the number of collisions in a rotation and increasing the number of bunches that can be in circulation. With this among other improvements, throughout the 1990s, CESR had the highest luminosity of any colliding-beam system in the world and became valuable as a synchrotron light source The pretzel orbits scheme was subsequently embraced and successfully incorporated into the Tevatron particle accelerator at Fermilab and the Large Electron–Positron Collider at CERN.
Overall, the physicist Maury Tigner has described Littauer as someone who was "very much interested in accelerators and was ... a pioneering controls designer and builder."
In 1974, Littauer was elected chair of Cornell's department of physics, a department which held 47 faculty members at the time. He remained in that position for three years.
Research
In addition to his work on accelerator construction and operation, Littauer was the author or co-author of a number of articles in physics journals. In 1958, he was one of several groups that published results regarding nucleon resonances, finding and establishing the properties of the state latter known as N(1520).
Teaching
Littauer had a longtime interest in how the teaching of physics, and teaching in general, could be improved. This included giving out lecture notes that emphasized scientific understanding coming out of mathematical formulae and experiments that could be performed in class.
Having seen that large lecture hall courses such as those given at Cornell tended to result in disengaged or absent students, during 1971 Littauer designed, built, and introduced an electronic classroom response system into his teaching of physics. It allowed the instructor to pose multiple-choice questions to the students, from which they would push buttons at their seats to anonymously register what they thought the answer was, giving the instructor immediate feedback as to students' level of understanding of the material being presented. The system was meant for large lecture classes and was permanently installed, with the location being the Rockefeller B room in the campus's Rockefeller Hall. As such, it was the first such response system at Cornell, and one of the first such anywhere in the country. In Fall 1972, Littauer published an account of the system, including photographs of the apparatus as it appeared both to students in their seats and to the teacher at the lectern, in the journal Educational Technology. He continued to use it in all his classes.
Moreso than with most such early efforts, Littauer's system was successful, with one later analysis attributing that success to the fact that the designer of the system was also the teacher who used it. Although other audience response technologies emerged over time and were utilized at Cornell, Littauer's system was still in place and in use within Rockefeller B some three decades later.
Anti-war activities
In 1962, Littauer was one of two dozen Cornell professors that signed onto a Committee for Peaceful Alternatives, an entity that was looking to run a candidate for New York's 33rd congressional district in the 1962 United States House of Representatives elections who would have better ideas for finding a solution to the nuclear arms race.
Littauer also became a national council member of the Federation of American Scientists.
With opposition to United States involvement in the Vietnam War being a major issue on American campuses, Littauer became one of the more outspoken members of the faculty in this regard. This including him being one of a number of physics faculty who stated they would not engage in teaching activities during the Moratorium to End the War in Vietnam in October 1969 and instead encouraged others to join them.
Starting in May 1971, Littauer headed the Air War Study Group, which was sponsored by Cornell's Center for International Studies and consisted of a 19-person group of professors and students who investigated the nature of the air attacks being conducted by the United States in the Vietnam War. They used only unclassified sources and discussions; as part of this Littauer made trips to Washington to interview participants. The report from the five-month study was distributed privately in November 1971; it established that despite the ongoing Vietnamization of the ground effort, the United States was still maintaining the air war with large numbers of munitions being delivered, akin to 1967 levels, but that these attacks were ineffective at halting Communist operations in Vietnam, Laos, and Cambodia. The report was written in a matter-of-fact way; while it was motivated by opposition to the war, Littauer said the study group was trying to be scholarly and fair in their work.
The study was subsequently revised and updated and published as The Air War in Indochina in August 1972 by the Beacon Press. By now the study group comprised some 21 scholars encompassing a number of different academic fields. Littauer was joined as editor of the volume by Norman Uphoff, a young professor of government at Cornell. A lengthy, front-page assessment of the volume in a positive vein appeared in the New York Times Book Review.
In a September 1972 op-ed run by the Los Angeles Times News Service, Littauer decried the air war as "remote, inefficient and indiscriminate", especially in the use of aerial gunships, cluster bombs, napalm, and B-52 Arc Light saturation bombing. Littauer did acknowledge the advent of "smart" laser-guided bombs as an improvement, but noted that their existence was not lowering the amount of conventional bombing being done. Decades later, the study was still being used as a source for analyses of the U.S. air effort.
Later years and honors
In 1991, Littauer was elected a Fellow of the American Physical Society. The citation for the achievement read, "For outstanding contributions to accelerator control systems, architecture and electronics, and in the use of feedback to cure instabilities."
In 1995, Littauer was awarded the Robert R. Wilson Prize for Achievement in the Physics of Particle Accelerators. The citation on the prize, also from the American Physical Society, read, "For his many contributions to accelerator technology, in particular his innovative conception and implementation of a mechanism to provide multifold increases in the luminosity of single-ring colliding beam facilities by the establishment of separated orbits of opposing, manу-bunch, particle beams. [...] the concept has been adopted, equally successfully, at the other high energy physics facilities of the world."
Littauer became a professor emeritus of Physics, but remained active in efforts to improve undergraduate education at Cornell. As part of this he maintained an interest in networked classroom technology.
Littauer died on October 19, 2009, at his home in Trumansburg, New York. His wife Alexandra had died four years earlier.
Selected publications
Accelerators: Machines of Nuclear Physics (Anchor Books, 1960) [co-author with Robert R. Wilson]
Pulse Electronics (McGraw-Hill, 1965)
The Air War in Indochina (Beacon Press, 1972) [co-editor with Norman Uphoff]
References
External links
Cornell Interactives: Physics tutorials provided by Raphael Littauer, Professor Emeritus of Physics, and Cornell University
Three Sisters: A True Holocaust Story of Love Luck and Survival, biographical account of S. Alexandra Littauer during World War II
1925 births
2009 deaths
People from Leipzig
Kindertransport refugees
Emigrants from Nazi Germany to the United Kingdom
Alumni of the University of Cambridge
Alumni of Christ's College, Cambridge
German emigrants to the United States
Cornell University faculty
People from Ithaca, New York
General Electric employees
20th-century American physicists
Particle physicists
American anti–Vietnam War activists
Fellows of the American Physical Society
People from Trumansburg, New York | Raphael M. Littauer | [
"Physics"
] | 2,598 | [
"Particle physicists",
"Particle physics"
] |
77,821,413 | https://en.wikipedia.org/wiki/Ioxynil | Ioxynil is a post-emergent selective nitrile herbicide. It is used in Australia, New Zealand and Japan to control broadleaf weeds via the inhibition of photosynthesis. It is used notably on onion crops, among others, normally at 300–900 g/Ha. It was introduced in 1966. The supply of ioxynil is decreasing, as of 2019 but the herbicide remains effective.
History
Ioxynil and bromoxynil (along with 2,4-DB and MCPB) were patented by Louis Wain as joint-head of the chemistry department at Wye College, and coincidentally discovered independently by May & Baker in England screening spare nitriles for herbicide activity, and by Amchem Products Inc in America doing similar screening, all in 1963. Commercial prospects were promising, as cereals could tolerate large amounts, over 2 lbs/ac; even 4 lbs/ac only temporarily scorches.
Wain theorised ioxynil and bromoxynil, the nitrile (-CN) group herbicides, because of the chemical similarity to a nitro (NO2) group, and on their success, the -SO2CH3 group was explored, leading to the discovery of methylsulphone herbicides.
May & Baker, a subsidiary of Rhone-Poulenc began ioxynil's, and the very similar bromoxynil's, production in Norwich in 1965, where it has continued for over 40 years. By 1968, ioxynil (as "Buctril") was registered for use in the USA, Canada, the UK, Australia, New Zealand, Japan, the West Indies and most of Europe.
In the 2010s, ioxynil was produced in South Africa to alleviate shortages.
Regulations
Today, ioxynil is banned in the EU and used in Brazil, China (as octanoate), New Zealand, Australia, South Africa and Japan.
The UK followed the EU's ban (taking effect 1 September 2015) to ban ioxynil's sale; the European approval lapsing under Regulation (EC) 1107/2009.
India and Columbia raised concerns about the EU's maximum allowed residue for ioxynil (amongst other pesticides), saying the EU's stance was too precautionary and not based on evidence, which is yet inconclusive on their genotoxicity. Bayer, Syngenta and others launched a lawsuit against the 2022 ban on exporting EU-prohibited pesticides from the EU to nations where they are legal, however the French Constitutional Court has upheld the ban.
Properties
Ioxynil is a flammable solid with a weak phenolic smell and decays under UV light. Ioxynil's octanoate, ioxynil octanoate, or 4-cyan-2,6-diiodphenyloctanoate, is likewise a colourless insoluble solid and hydrolyses to ioxynil in basic conditions.
The taste of ioxynil is "slight, not characteristic."
Mechanism and effect
Ioxynil acts via photosynthesis inhibition. It and bromoxynil uncouple oxidative phosphorylation and inhibit photosynthetic phosphorylation. Ioxynil additionally breaks down into iodide ions which inhibit plant growth again. Ioxynil may also inhibit photoreduction of ferricyanide, fixation of carbon dioxide, photoreduction of NAPD or of endogenous plastoquinone. Ioxynil acts as an electron transport inhibitor and uncoupling agent.
Symptoms on weeds appear after a few hours or days. Areas of collapsed tissue appear, rapidly becoming necrotic. In good conditions on small plants, necrosis may complete within two days but some weeds can take up to three weeks to die. Effectiveness is enhanced if any times of high humidity occur 1 or 2 days after application. Light and temperature speed up herbicidal action.
Ioxynil is a Group C, (Australia), C3 (Global) or Group 6, (numeric) resistance class herbicide.
Toxicology
Ioxynil is toxic to mammals, with an oral LD50 of 110 mg/kg (rats), dermal LD50 of 800 mg/kg, and inhalative LC50 of 0.38 mg/L over four hours. Ioxynil is toxic to fish, with a 96 hour LC50 of 6.8 mg/L, and 3.9 mg/L for daphnia. Plankton and bloodworms are also effected. The oral LD50s in mice, guinea-pigs, rabbits and dogs respectively are 230, 76, 180, > 100 mg/kg.
Ioxynil can affect the human thyroid via binding to transthyretin, a thyroid hormone binding protein which transports thyroid hormone in the blood. It can provoke thyroid tumors in rats, and can disrupt zebrafish's heart development.
Environmental fate
Ioxynil is a contact herbicide and has no residual soil activity or translocation, so spray coverage must be thorough as unsprayed weeds will not be controlled; large enough weeds may even contain surviving portions that resprout, and resistance can occur at later growth stages. Translocated chemical may produce chlorosis but is unlikely to be lethal.
Ioxynil bioaccumulates, although it does not linger long in the environment. Ioxynil, bromoxynil, and their octanoate variants, leave negligible residues after use on crops. In all cases, under 0.01 ppm, the limit of detection, though some inactive content may be adsorbed into the soil.
Lists
Ioxynil is or has been sold under these tradenames: Ioxynil, Unyunox, Totril, Toxynil, Hawk, Hocks, Sanoxynil, Iotril, Certrol, Actril, Actrilawn, Bentrol, Belgran, Bronx, Cipotril, Dantril, Oxytril, Mextrol-Biox, Sanoxynil, Shamseer-2, Stellox, Iotox, Iconix and Trevespan. Some products include multiple active ingredients.
Ioxynil has been sold in formulations also containing bromoxynil and isoproturon.
It is used to control these weeds: bellvine, burr medic, capeweed, chickweed, climbing buckwheat, common heliotrope, common sowthistle, corn gromwell, dandelion, dead nettle, fat-hen, fumitory, green amaranth, green crumbleweed, bittercress, ox tongue, pigweed, potato weed, saffron thistle, scarlet pimpernel, shepherd's purse, slender celery, smallflower mallow, stagger weed, threecornered Jack, three flowered nightshade, turnip weed, Ward's weed, wild radish, wild turnip, wireweed, annual sowthistle, cornbind, musky storksbill, willow weed, buttercup, field pansy, groundsel, plantain, speedwell, stinking mayweed, the knotweed family broadly, in particular tartary buckwheat, the composite or sunflower family, chamomile, mayweed, some borages, fiddlenecks, gromwells and prickly paddy melon.
Crops situations which ioxynil has been used on include: onions, spring onions, welsh onions, garlic onions, cereals, leeks, garlic, shallots, flax, sugarcane, forage grasses, lawns and turf. Peas, oats, maize, sorghum and rice show high tolerance. Limited resistance is seen in lucerne, clover and carrot.
References
External links
Herbicides
Nitriles
Products introduced in 1966
Phenols
Iodoarenes | Ioxynil | [
"Chemistry",
"Biology"
] | 1,684 | [
"Herbicides",
"Nitriles",
"Biocides",
"Functional groups"
] |
77,822,737 | https://en.wikipedia.org/wiki/Kawarau%20Gibbston%20Dark%20Sky%20Park | The Kawarau Gibbston Dark Sky Park is a dark-sky preserve located between Cromwell and Queenstown in the Queenstown-Lakes District in the South Island of New Zealand. It covers an area of along a section of the Kawarau River, and is centred on the small community of Gibbston. The Kawarau Gibbston Dark Sky Park was accredited as an International Dark Sky Park by DarkSky International in May 2024. It is the first dark sky preserve to be accredited in the Otago Region, the seventh dark sky preserve in New Zealand, and the third International Dark Sky Park in the country (after Wai-iti Dark Sky Park and Oxford Forest Conservation Area).
The Kawarau Gibbston Dark Sky Park is located in a valley and shielded from light pollution by high mountains, leading to a particularly dark night sky. Central regions of the Magellanic Clouds and the Milky Way galaxy can be readily viewed and photographed, as well as the Aurora Australis.
The application for the dark sky park accreditation was prepared by a volunteer group, the Gibbston Community Association. The lead author for the application was Brian Boyle, an astrophysicist who moved to the Queenstown-Lakes District at the end of 2019. The application reports that night sky luminance in the park is 21.75 mag/arcsec2 (corresponding to Bortle scale 2 and on the threshold of Bortle scale 1).
The Gibbston Community Association is a registered charity in New Zealand. The association advocates for the protection of the dark sky, promotes good lighting practices and is introducing a voluntary certification code for lighting of homes and businesses. The association hopes to work with nearby communities at Lowburn, Bannockburn and Cardrona to expand the dark sky preserve to include the Remarkables and Pisa conservation areas.
References
External links
Official website
Antimony Observatory - observatory in Gibbston
Winterstellar Charitable Trust
2024 establishments in New Zealand
Dark-sky preserves in New Zealand
Queenstown-Lakes District | Kawarau Gibbston Dark Sky Park | [
"Astronomy"
] | 404 | [
"Dark-sky preserves",
"Dark-sky preserves in New Zealand"
] |
77,823,491 | https://en.wikipedia.org/wiki/4-Aminobutanal | 4-Aminobutanal, also known as γ-aminobutyraldehyde, 4-aminobutyraldehyde, or GABA aldehyde, is a metabolite of putrescine and a biological precursor of γ-aminobutyric acid (GABA). It can be converted into GABA by the actions of diamine oxidase (DAO) and aminobutyraldehyde dehydrogenase (ABALDH) (e.g., ALDH9A1). Putrescine is converted into 4-aminobutanal via monoamine oxidase B (MAO-B). However, biosynthesis of GABA from polyamines like putrescine is a minor metabolic pathway in the brain.
The related compound γ-hydroxybutyraldehyde (GHBAL) is a prodrug of γ-hydroxybutyric acid (GHB) as well as a metabolic intermediate in the conversion of 1,4-butanediol (1,4-BD) into GHB. However, aliphatic aldehydes like GHBAL are caustic, strong-smelling, and foul-tasting, and ingestion is likely to be unpleasant and result in severe nausea and vomiting.
See also
N-Acetyl-γ-aminobutyraldehyde (N-acetyl-GABAL)
References
Aldehydes
Amines
GABA analogues
Neurotransmitter precursors
Prodrugs | 4-Aminobutanal | [
"Chemistry"
] | 322 | [
"Functional groups",
"Prodrugs",
"Chemicals in medicine",
"Amines",
"Bases (chemistry)"
] |
77,823,783 | https://en.wikipedia.org/wiki/4-Amino-1-butanol | 4-Amino-1-butanol, or 4-aminobutanol, also known as 4-hydroxybutylamine, is an alkanolamine and an analogue and precursor of the neurotransmitter γ-aminobutyric acid (GABA).
The structural relation of 1,4-butanediol (1,4-BD) to γ-hydroxybutyric acid (GHB) is analogous to the relation of 4-amino-1-butanol to GABA. 1,4-BD is a known prodrug of GHB which is converted into it through the actions of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). γ-Hydroxybutyraldehyde (GHBAL) is an intermediate in this pathway, whereas the analogous intermediate structure for 4-amino-1-butanol and GABA is γ-aminobutyraldehyde (GABAL). Similar to the conversion of 1,4-BD into GHB, 4-amino-1-butanol is converted into GABAL by aldehyde reductase (ALR) and GABAL is converted into GABA by ALDH.
References
Alcohols
Amines
GABA analogues
GABA receptor agonists
Neurotransmitter precursors
Prodrugs | 4-Amino-1-butanol | [
"Chemistry"
] | 296 | [
"Functional groups",
"Prodrugs",
"Amines",
"Organic compounds",
"Bases (chemistry)",
"Chemicals in medicine",
"Organic compound stubs",
"Organic chemistry stubs"
] |
77,824,235 | https://en.wikipedia.org/wiki/Neurotransmitter%20prodrug | A neurotransmitter prodrug, or neurotransmitter precursor, is a drug that acts as a prodrug of a neurotransmitter. A variety of neurotransmitter prodrugs have been developed and used in medicine. They can be useful when the neurotransmitter itself is not suitable for use as a pharmaceutical drug owing to unfavorable pharmacokinetic or physicochemical properties, for instance high susceptibility to metabolism, short elimination half-life, or lack of blood–brain barrier permeability. Besides their use in medicine, neurotransmitter prodrugs have also been used as recreational drugs in some cases.
Monoamine prodrugs
Monoamine neurotransmitter prodrugs include the catecholamine precursors and prodrugs L-phenylalanine, L-tyrosine, L-DOPA (levodopa), L-DOPS (droxidopa), and dipivefrine (O,O'-dipivalylepinephrine), as well as the serotonin and melatonin precursors and prodrugs L-tryptophan and L-5-hydroxytryptophan (5-HTP; oxitriptan). Other dopamine prodrugs, including etilevodopa, foslevodopa, melevodopa, XP-21279, DopAmide, DA-Phen, O,O'-diacetyldopamine, O,O'-dipivaloyldopamine, docarpamine, gludopa, and gludopamine, have also been developed. Dopamantine (N-adamantanoyl dopamine) is another possible attempt at a dopamine prodrug. Other serotonin prodrugs have been developed as well, such as the renally-selective L-glutamyl-5-hydroxy-L-tryptophan (glu-5-HTP).
5-HTP is additionally a prodrug of N-methylated tryptamine psychedelic trace amines, such as N-methylserotonin (NMS; norbufotenin) and bufotenin (5-hydroxy-N,N-dimethyltryptamine; 5-HO-DMT). The same is also true of L-tryptophan, which is transformed into tryptamine as well as into N-methyltryptamine (NMT) and N,N-dimethyltryptamine (N,N-DMT). Dependent on these transformations, both tryptophan and 5-HTP produce the head-twitch response (HTR), a behavioral proxy of psychedelic effects, at sufficiently high doses in animals. O-Acetylbufotenine and O-pivalylbufotenine are thought to be centrally active prodrugs of the peripherally selective bufotenin.
Although they are not endogenous neurotransmitter prodrugs, "false" or "substitute" neurotransmitter prodrugs, such as α-methyltryptophan and α-methyl-5-hydroxytryptophan (which are prodrugs of α-methylserotonin, a substitute neurotransmitter of serotonin), have also been developed. Analogously, ibopamine and fosopamine are prodrugs of epinine (N-methyldopamine; deoxyepinephrine).
GABA prodrugs
γ-Aminobutyric acid (GABA) prodrugs include progabide and tolgabide. Picamilon has been claimed to be a prodrug of GABA, but has not actually been demonstrated to be converted into GABA. Pivagabine was once thought to be a prodrug of GABA, but this proved not to be the case.
4-Amino-1-butanol is known to be converted into GABA through the actions of aldehyde reductase (ALR) and aldehyde dehydrogenase (ALDH). 4-Amino-1-butanol is to GABA as 1,4-butanediol (4-hydroxy-1-butanol; 1,4-BD) is to γ-hydroxybutyric acid (GHB) (with 1,4-BD being a well-known prodrug of GHB). The metabolic intermediate γ-aminobutyraldehyde (GABAL) is also converted into GABA.
GHB prodrugs
A number of γ-hydroxybutyric acid (GHB) prodrugs are known. These include 1,4-butanediol (1,4-BD) and γ-butyrolactone (GBL), as well as the metabolic intermediate γ-hydroxybutyraldehyde (GHBAL).
Acetylcholine prodrugs
Acetylcholine precursors and prodrugs like choline, phosphatidylcholine (lecithin), citicoline (CDP-choline), and choline alphoscerate (α-GPC) are known and have been researched.
References
Neurotransmitter precursors
Neurotransmitters
Prodrugs | Neurotransmitter prodrug | [
"Chemistry"
] | 1,188 | [
"Neurochemistry",
"Neurotransmitters",
"Prodrugs",
"Chemicals in medicine"
] |
77,825,154 | https://en.wikipedia.org/wiki/Dordaviprone | Dordaviprone is an investigational new drug that is being evaluated for the treatment of diffuse intrinsic pontine glioma (a type of brain tumor). It is dopamine receptor D2 antagonist and an allosteric activator of the mitochondrial caseinolytic protease P.
References
Imidazopyrimidines | Dordaviprone | [
"Chemistry"
] | 73 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
77,825,222 | https://en.wikipedia.org/wiki/Wetland%20virus | Wetland virus or WELV is a tick borne Orthonairovirus which can infect humans. It can produce fever, headache, dizziness, malaise, arthritis and less commonly petechiae, localized lymphadenopathy. Complications may include neurological symptoms.
Virology
The Wetland virus orthonairovirus (WELV) is a member of the genus Orthonairovirus, family Nairoviridae of RNA viruses. It was first identified in 2019 in a Chinese person in Jinzhou, Liaoning province NorthEastern China after a visit to a wetland park in Yakeshi, Inner Mongolia. Three different strains were identified one from the patient and two from ticks.
Its sequence is most similar to the Tofla virus from Japan.
Hosts and transmission
The Wetland virus was found in mice, sheep, pigs, and horses, but not dogs or cattle. It was found in about 2% of 14,500 different ticks in Northeast China with the highest prevalence (6%) in Haemaphysalis concinna.
Experimental infection showed that WELV caused lethal disease even in immunocompetent mice, unlike the remainder of the viruses in Nairoviridae family.
Signs and symptoms
Symptoms of infection with the Wetland virus are fever, headache, dizziness, malaise, myalgia (muscle pain), arthritis, and back pain. Less commonly there are petechiae and localized lymphadenopathy. One person also had severe neurological symptoms, but all recovered without sequelae. Symptoms and signs resemble those of Crimean–Congo hemorrhagic fever, and the differential diagnosis includes severe fever with thrombocytopenia syndrome and spotted fever.
References
Nairoviridae
Unaccepted virus taxa | Wetland virus | [
"Biology"
] | 362 | [
"Viruses",
"Controversial taxa",
"Virus stubs",
"Unaccepted virus taxa",
"Biological hypotheses"
] |
77,825,280 | https://en.wikipedia.org/wiki/Funobactam | Funobactam is an investigational new drug that is being evaluated for the treatment of hospital-acquired bacterial pneumonia. It is a β-lactamase inhibitor.
References
Diazabicyclooctanes
Imidazolines
Oxadiazoles
Sulfonic acids
Sulfate esters
Cyclopropyl compounds
Guanidinium compounds
Ureas
Zwitterions | Funobactam | [
"Physics",
"Chemistry"
] | 77 | [
"Pharmacology",
"Matter",
"Functional groups",
"Medicinal chemistry stubs",
"Organic compounds",
"Zwitterions",
"Sulfonic acids",
"Pharmacology stubs",
"Ions",
"Ureas"
] |
77,825,441 | https://en.wikipedia.org/wiki/Histamine%20glutarimide | Histamine glutarimide is an investigational new drug that is being evaluated for the treatment of cough in acute respiratory infection. It is a glutaminyl cyclase inhibitor.
References
Glutarimides
Imidazoles | Histamine glutarimide | [
"Chemistry"
] | 53 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
77,826,356 | https://en.wikipedia.org/wiki/Algebraic%20homotopy | In mathematics, algebraic homotopy is a research program on homotopy theory proposed by J.H.C. Whitehead in his 1950 ICM talk, where he described it as:
In spirit, the program is somehow similar to Grothendieck's homotopy hypothesis. However, according to Ronnie Brown, "Looking again at Esquisses d'un Progamme, it seems that programme has currently little relation to Whitehead's."
References
https://ncatlab.org/nlab/show/algebraic+homotopy
Handbook of Algebraic Topology edited by I.M. James
Further reading
https://ncatlab.org/nlab/show/Algebraic+Homotopy, an entry about a book
Homotopy theory
Homotopical algebra | Algebraic homotopy | [
"Mathematics"
] | 164 | [
"Topology stubs",
"Topology"
] |
77,827,597 | https://en.wikipedia.org/wiki/Masupirdine | Masupirdine is an investigational new drug that is being evaluated for the treatment of agitation in Alzheimer's dementia. It is a selective 5-HT6 receptor antagonist.
References
Indoles
4-Methylpiperazin-1-yl compounds
Sulfonamides
Bromobenzene derivatives
Methoxy compounds | Masupirdine | [
"Chemistry"
] | 68 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
77,827,739 | https://en.wikipedia.org/wiki/Obefazimod | Obefazimod is an investigational new drug that is being evaluated for the treatment of ulcerative colitis. It is miR-124 micro RNA upregulator.
References
Anilines
Quinolines
Trifluoromethoxy compounds
Chlorobenzene derivatives | Obefazimod | [
"Chemistry"
] | 60 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
77,827,864 | https://en.wikipedia.org/wiki/Povorcitinib | Povorcitinib is an investigational new drug that is being evaluated for the treatment of the skin conditions hidradenitis suppurativa and chronic prurigo. It is a JAK1 inhibitor.
References
Azetidines
Benzamides
Janus kinase inhibitors
Pyrazoles
Trifluoromethyl compounds
Nitriles | Povorcitinib | [
"Chemistry"
] | 73 | [
"Pharmacology",
"Functional groups",
"Medicinal chemistry stubs",
"Pharmacology stubs",
"Nitriles"
] |
77,828,029 | https://en.wikipedia.org/wiki/Sebetralstat | Sebetralstat is an investigational new drug that is being evaluated for the treatment of hereditary angioedema. It is a plasma kallikrein inhibitor.
References
Pyridines
Pyridones
Pyrazoles
Carboxamides
Fluoroarenes
Methoxy compounds | Sebetralstat | [
"Chemistry"
] | 62 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
77,828,177 | https://en.wikipedia.org/wiki/Sepetaprost | Sepetaprost is an investigational new drug that is being evaluated for the treatment of open angle glaucoma and ocular hypertension. It is an agonist of the prostaglandin EP3 and F receptors.
References
Oxepanes
2-Fluorophenyl compounds
Isopropyl esters
Diols | Sepetaprost | [
"Chemistry"
] | 71 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
77,828,478 | https://en.wikipedia.org/wiki/Tigulixostat | Tigulixostat is an investigational new drug that is being evaluated for the treatment of gout. It is a xanthine oxidase inhibitor.
References
Antigout agents
Indoles
Carboxylic acids
Isopropylamino compounds
Nitriles
Pyrazoles | Tigulixostat | [
"Chemistry"
] | 60 | [
"Pharmacology",
"Carboxylic acids",
"Functional groups",
"Medicinal chemistry stubs",
"Pharmacology stubs",
"Nitriles"
] |
77,829,061 | https://en.wikipedia.org/wiki/Bathurst%20studentship | The Bathurst studentship was a fund for graduates of the natural science tripos at the women's colleges at the University of Cambridge to continue their scientific research.
It was established in 1879 by The Hon. Lady Evelyn Selina Bathurst (often called Selina Bathurst, d. 1946). She was the daughter of Allen Bathurst, 6th Earl Bathurst and his second wife Evelyn, née Hankey. She contributed money and equipment for the establishment of the Balfour Biological Laboratory for Women. On 18 June 1898, she married Major George Coryton Lister. They had two children. She died on 16 April 1946.
The Bathurst Studentship, awarded 'from time to time,' was taken up by dozens of women scientists in the late nineteenth and twentieth centuries. Students would work independently, supported by academic supervisors, and were granted bench space in the Balfour Biological Laboratory for Women for their experiments.
Notable recipients
Florence Eves (1881–2)
Alice Johnson (1882–3)
Marion Greenwood (1883–4)
Anna Bateson (1887–9)
Edith Saunders (1888–9)
Elizabeth Eleanor Field (1891–3)
Mary Tebb (1891–3)
Ethel Skeat (1895–7)
Mildred Gostling (1899–1900)
Sibille Ford (1900–2)
Ida Smedley (1901–3)
Jessie Slater (1903–5)
Muriel Onslow (1904)
Edith Gertrude Willcock (1904–5)
Annie Homer (1905)
Mary Gladys Sykes (1908–9)
Margaret Hume (1912)
Molly F. Mare (1938)
Nancy Kirk (1939)
June Sutor (1954)
Brigid Hogan (1966)
Rachel Alcock
Mary Bernheim
Dorothy Jordan Lloyd
Cecilia Payne-Gaposchkin
Lilian Sheldon
References
Awards and prizes of the University of Cambridge
Women in science and technology | Bathurst studentship | [
"Technology"
] | 365 | [
"Women in science and technology"
] |
77,829,188 | https://en.wikipedia.org/wiki/Seleqseya | Seleqṣeya () was the Israeli policy of selective immigration imposed on poor Moroccan Jews adopted in mid 1951. It was applied by Cadima, the Zionist apparatus overseen by agents from Mossad LeAliyah and the Jewish Agency that administered the migration of Moroccan Jews to Israel from 1949 to 1956.
History
In the summer of 1951, the recently established State of Israel sought to severely limit the immigration of poor Moroccan Jews by adopting Seleqṣeya, a policy of selective immigration. With this policy, the Jewish Agency discriminated against poor Moroccan Jews unable to pay for their own immigration, families without a breadwinner in the age range of 18-45, and families with a member in need of medical care. The American historian Norman Stillman described the Seleqṣeya as a "draconian and frequently cruel policy." This policy was also imposed to a lesser extent upon Tunisian Jews.
The policy caused bitterness among Moroccan and Maghrebi Jews. It was debated among members of Israeli administration, and it was rescinded in 1953 as Cadima sought to increase its activity in the twilight of French colonial rule in Morocco.
Justifications
Stillman writes that when the Seleqṣeya was imposed, the recently established State of Israel was overwhelmed with immigrants and in a state of economic crisis. He adds that Jews living under French rule in the Maghreb were not perceived to be in the same kind of danger as Jews in Iraq, Yemen, and Libya. He also writes that, though it was not expressed, the policy may have been influenced by the prejudice of European Ashkenazim veterans in Israel against Sephardic/Mizrahi Jews in general, and Maghrebi Jews and Moroccan Jews in particular. Epithets such as Maroqo sakkin ( 'Morocco of the knife) demonstrate the prejudiced view of Moroccans as primitive and violent.
References
Jewish Moroccan history
Colonial history of Morocco
Aliyah
Discrimination
Immigration to Israel
Words and phrases in Modern Hebrew
Jewish exodus from the Muslim world | Seleqseya | [
"Biology"
] | 411 | [
"Behavior",
"Aggression",
"Discrimination"
] |
77,829,349 | https://en.wikipedia.org/wiki/Kitaev%20chain | In condensed matter physics, the Kitaev chain is a simplified model for a topological superconductor. It models a one dimensional lattice featuring Majorana bound states. The Kitaev chain have been used as a toy model of semiconductor nanowires for the development of topological quantum computers. The model was first proposed by Alexei Kitaev in 2000.
Description
Hamiltonian
The tight binding Hamiltonian in of a Kitaev chain considers a one dimensional lattice with N site and spinless particles at zero temperature, subjected to nearest neighbour hoping interactions, given in second quantization formalism as
where is the chemical potential, are creation and annihilation operators, the energy needed for a particle to hop from one location of the lattice to another, is the induced superconducting gap (p-wave pairing) and is the coherent superconducting phase. This Hamiltonian has particle-hole symmetry, as well as time reversal symmetry.
The Hamiltonian can be rewritten using Majorana operators, given by
,
which can be thought as the real and imaginary parts of the creation operator . These Majorana operator are Hermitian operators, and anticommutate,
.
Using these operators the Hamiltonian can be rewritten as
where .
Trivial phase
In the limit , we obtain the following Hamiltonian
where the Majorana operators are coupled on the same site. This condition is considered a topologically trivial phase.
Non-trivial phase
In the limit and , we obtain the following Hamiltonian
where every Majorana operator is coupled to a Majorana operator of a different kind in the next site. By assigning a new fermion operator , the Hamiltonian is diagonalized, as
which describes a new set of N-1 Bogoliubov quasiparticles with energy t. The missing mode given by couples the Majorana operators from the two endpoints of the chain, as this mode does not appear in the Hamiltonian, it requires zero energy. This mode is called a Majorana zero mode and is highly delocalized. As the presence of this mode does not change the total energy, the ground state is two-fold degenerate. This condition is a topological superconducting non-trivial phase.
The existence of the Majorana zero mode is topologically protected from small perturbation due to symmetry considerations. For the Kitaev chain the Majorana zero mode persist as long as and the superconducting gap is finite. The robustness of these modes makes it a candidate for qubits as a basis for topological quantum computer.
Bulk case
Using Bogoliubov-de Gennes formalism it can be shown that for the bulk case (infinite number of sites), that the energy yields
,
and it is gapped, except for the case and wave vector . For the bulk case there are no zero modes. However a topological invariant exists given by
,
where is the Pfaffian operation. For , the invariant is strictly and for , corresponding to the trivial and non-trivial phases from the finite chain, respectively. This relation between the topological invariant from the bulk case and the existence of Majorana zero modes in the finite case is called a bulk-edge correspondence.
Experimental efforts
One possible realization of Kitaev chains is using semiconductor nanowires with strong spin–orbit interaction to break spin-degeneracy, like indium antimonide or indium arsenide. A magnetic field can be applied to induce Zeeman coupling to spin polarize the wire and break Kramers degeneracy. The superconducting gap can be induced using Andreev reflection, by putting the wire in the proximity to a superconductor. Realizations using 3D topological insulators have also been proposed.
There is no single definitive way to test for Majorana zero modes. One proposal to experimentally observe these modes is using scanning tunneling microscopy. A zero bias peak in the conductance could be the signature of a topological phase. Josephson effect between two wires in superconducting phase could also help to demonstrate these modes.
In 2023 QuTech team from Delft University of Technology reported the realization of a "poor man's" Majorana that is a Majorana bound state that is not topologically protected and therefore only stable for a very small range of parameters. It was obtained in a Kitaev chain consisting of two quantum dots in a superconducting nanowire strongly coupled by normal tunneling and Andreev tunneling with the state arising when the rate of both. Some researches have raised concerns, suggesting that an alternative mechanism to that of Majorana bound states might explain the data obtained.
See also
Su–Schrieffer–Heeger chain
References
Condensed matter physics
Superconductivity | Kitaev chain | [
"Physics",
"Chemistry",
"Materials_science",
"Engineering"
] | 963 | [
"Electrical resistance and conductance",
"Physical quantities",
"Superconductivity",
"Phases of matter",
"Materials science",
"Condensed matter physics",
"Matter"
] |
77,829,631 | https://en.wikipedia.org/wiki/Tinlarebant | Tinlarebant is a investigational new drug that is being evaluated to treat dry macular degeneration and Stargardt disease. It is a retinol binding protein 4 antagonist.
References
Pyrazolopyridines
Piperidines
Carboxamides
Trifluoromethyl compounds
Acetamides | Tinlarebant | [
"Chemistry"
] | 66 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
77,829,705 | https://en.wikipedia.org/wiki/Zatolmilast | Zatolmilast is a investigational new drug that is being evaluated to treat fragile X syndrome. It is a PDE4D allosteric inhibitor.
References
Pyridines
Carboxylic acids
Trifluoromethyl compounds
Chloroarenes | Zatolmilast | [
"Chemistry"
] | 57 | [
"Pharmacology",
"Carboxylic acids",
"Functional groups",
"Medicinal chemistry stubs",
"Pharmacology stubs"
] |
77,829,729 | https://en.wikipedia.org/wiki/Catherine%20O%27Sullivan | Catherine O'Sullivan is an Irish environmental engineer who is Professor of Particulate Soil Mechanics and Head of the Geotechnics Section at Imperial College London. She uses discrete element modelling to understand fundamental processes in sand and soils.
Early life and education
O'Sullivan is from Ireland. She was an undergraduate at University College Cork, and started a master's degree in soil mechanics. She spent six months working in a geotechnical engineering consultancy. She was awarded a scholarship to complete a master's degree in geotechnical engineering completed her doctorate at the University of California, Berkeley, where she developed discrete element methods to model granular materials. After graduating she moved to University College Dublin, where she spent two years as a College Lecturer.
Research and career
In 2004, O'Sullivan joined Imperial College London as a lecturer. She was promoted to Professor in 2017. Her research considers the behaviour of granular materials, including soil and sand.
In 2023, O'Sullivan became the first woman to be editor of the Journal of Geotechnical & Geoenvironmental Engineering. She is enthusiastic about sustainability, and was involved with the development of a graduate course in geotechnical engineering for offshore renewables.
Awards and honours
2016 Shamsher Prakash Research Award
2021 Imperial College London President's Awards for Teaching Innovation
Selected publications
References
Living people
Alumni of University College Cork
University of California, Berkeley alumni
Academics of Imperial College London
Environmental engineers
Year of birth missing (living people) | Catherine O'Sullivan | [
"Chemistry",
"Engineering"
] | 296 | [
"Environmental engineers",
"Environmental engineering"
] |
77,829,756 | https://en.wikipedia.org/wiki/IPhone%2016 | The iPhone 16 and iPhone 16 Plus are smartphones developed and marketed by Apple. They are the eighteenth-generation iPhones, succeeding the iPhone 15 and iPhone 15 Plus. The devices were unveiled alongside the higher-priced iPhone 16 Pro and 16 Pro Max during the Apple Event at Apple Park in Cupertino, California, on September 9, 2024.
History
The devices were unveiled during an event on September 9, 2024, marking the first time an iPhone release had been announced on a Monday. It is also the first iPhone not to include Apple stickers in the box, as Apple removed them for environmental reasons. Stickers can be included if a customer asks for them at an Apple Store.
Design
Like the iPhone 15, the device features rounded edges, a slightly curved display, and back glass.
Material
The iPhone 16 is equipped with an aluminum design with a color infused glass back.
Display
The iPhone 16 and iPhone 16 Plus retain their screen sizes of 6.1 inches and 6.7 inches, respectively. They feature a full-edge screen design with slim borders.
For more specifics, here is each individual display
iPhone 16: 6.1-inch Super Retina XDR OLED display with a resolution of 2556x1179 pixels.
iPhone 16 Plus: 6.7-inch Super Retina XDR OLED display with a resolution of 2796x1290 pixels.
Camera
iPhone 16 features a more refined dual-lens array on the back, with a 48 megapixel Fusion wide-angle lens and 12 megapixel ultra-wide lens. The cameras are now aligned vertically, similar to iPhone 12, instead of diagonally like on iPhone 15, enabling spatial video capture.
There is also an improved Photographic Styles feature for real-time lighting and color adjustments, allowing specific tones and colors to be manipulated.
Colors
The iPhone 16 and 16 Plus come in five colors: Ultramarine, Teal, Pink, White, and Black.
Hardware
The iPhone 16 and the iPhone 16 Plus use an Apple A18 system on a chip. The chip is optimized for running Generative artificial intelligence and features a Neural Engine that is twice as fast as its predecessor.
The iPhone 16 includes an updated 48-megapixel Fusion camera, the same resolution as the iPhone 15, with 2 μm, quad pixel PDAF, sensor-shift OIS, 100% Focus Pixels, support for super-high-resolution photos (24MP and 48MP). It has a new ultrawide camera with a wider aperture, automatic focus and 1.4 μm, 100% Focus Pixels.
All iPhone 16 models have an improved thermal design. The main logic board has been updated, centralizing chip placement and optimizing the surrounding architecture. The recycled aluminum substructure dissipates heat for up to 30 percent higher sustained performance for gaming.
Every model in the iPhone 16 lineup has support for WiFi 7.
Action Button
The iPhone 16 and iPhone 16 Plus come with the Action Button, first featured on the iPhone 15 Pro lineup. By default, the Action Button toggles silent mode. However, users can change the button's feature to do different things other than silent mode, like open the Camera app or toggle a focus mode.
Camera Control button
All iPhone 16 models now come with a new button called Camera Control. This button is on the right side of the device, and allows the user to open the camera app, switch between different camera controls and features, and taking photos and videos. The button can distinguish between light and hard presses. By pressing the button once, it opens the camera app. By lightly pressing it twice, it opens a small menu with different camera controls, such as zoom or tone. Pressing the button hard once takes a photo, while holding for a few seconds starts a video.
Battery and charging
The iPhone 16 has been upgraded in terms of battery capacity.
The base iPhone 16 has video playback duration of up to 22 hours, while the iPhone 16 Plus has video playback up to 27 hours. The iPhone 16 has duration of audio playback up to 80 hours, 20% less than the iPhone 16 Plus with 100 hours of audio playback. The MagSafe wireless charging standard has been refreshed with a longer cable as an option, allowing the iPhone 16 and iPhone 16 Plus to charge at a faster speed of 25W with a 30W power adapter.
Enclosure
The enclosure is made up of 85% recycled content.
Software
The iPhone 16 launched with iOS 18. While the device was announced alongside Apple Intelligence, these features were delayed until after release.
iOS 18 includes RecoveryOS on the iPhone 16 series that allows users to recover and restore firmware wirelessly using another iPhone.
Specifications
The iPhone 16 and 16 Plus have a vertical camera layout, similar to the iPhone 12, as opposed to the diagonal layout for iPhone 13, iPhone 14, and iPhone 15. USB Type-C port is used, albeit with USB 2.0 data transfer speeds up to 480 Mb/s.
Other features
Action Button - customizable button for very quick access to various functions
Water and Dust Resistance - Rated IP68 (maximum depth of 6 meters up to 30 minutes)
Operating Systems - iOS 18 with Apple intelligence for enhanced privacy and productivity features.
Release and pricing
The iPhone 16 has a starting price of , while the iPhone 16 Plus starts at . Pre-orders began on September 13, 2024, and sales started September 20.
Availability by region
September 20, 2024
Australia
Austria
Bahrain
Brazil
Belgium
Canada
China
Croatia
Czech Republic
Denmark
Finland
France
Germany
Greece
Hong Kong
Hungary
India
Italy
Ireland
Japan
Luxembourg
Malaysia
Mexico
Netherlands
New Zealand
Norway
Oman
Poland
Portugal
Qatar
Saudi Arabia
Serbia
Singapore
Slovakia
South Africa
South Korea
Spain
Sweden
Switzerland
Taiwan
Thailand
Turkey
United Arab Emirates
United Kingdom
United States
September 26, 2024
Israel
September 27, 2024
Macao
Vietnam
Malta
October 18, 2024
Bangladesh
Philippines
Indonesian sales ban
On October 20, 2024, the Indonesian Ministry of Industry announced a formal ban on the sale and use of iPhone 16 models in Indonesia, citing that Apple has not fulfilled their promised investments in the country, and failing to meet the 40% local content requirement threshold for certification. Apple subsequently offered a $100 million investment in exchange for lifting of the ban, but the Ministry of Industry rejected this offer, stating that it "has not met principles of fairness" and demanded a larger amount, which later said to be at least $1 billion.
Reception
The iPhone 16 has received positive feedback for several aspects, but also shows a few limitations. The upgraded design is a favourite, bringing a refreshed aesthetic with the available vibrant color options, which feel more dynamic than past models. The display maintains Apple's Super Retina HDR quality, but is limited to a 60 Hz refresh rate, which some users find outdated compared to faster displays on cheaper competitor phones. The iPhone 16 Plus has been praised, weighing 30 grams less and having longer battery life than the iPhone 16 Pro Max, while having a similar screen size to the Pro Max. The "base model iPhone has often felt like a notable downgrade from its Pro counterparts, but that’s not the case this year", with the iPhone 16 and 16 Plus having enough features to make the 16 Pro and 16 Pro Max somewhat redundant.
References
IPhone
Mobile phones introduced in 2024
Products introduced in 2024
Mobile phones with 4K video recording
Mobile phones with multiple rear cameras
Flagship smartphones | IPhone 16 | [
"Technology"
] | 1,499 | [
"Flagship smartphones"
] |
77,829,808 | https://en.wikipedia.org/wiki/IPhone%2016%20Pro | The iPhone 16 Pro and iPhone 16 Pro Max are smartphones developed and marketed by Apple Inc. Alongside the iPhone 16 and iPhone 16 Plus, they form the eighteenth generation of the iPhone, succeeding the iPhone 15 Pro and iPhone 15 Pro Max, and were announced on September 9, 2024, and released on September 20, 2024. The iPhone 16 Pro and iPhone 16 Pro Max include larger 6.3-inch and 6.9-inch displays, a faster processor, upgraded wide and ultra-wide cameras, support for Wi-Fi 7, larger batteries, and come pre-installed with the iOS 18 operating system.
Specifications
Design and display
The iPhone 16 Pro models continue the edge-to-edge display design but introduce thinner display borders, giving them the thinnest borders of any Apple product to date; iPhone 16 Pro and iPhone 16 Pro Max feature larger 6.3-inch and 6.9-inch Super Retina XDR OLED displays, respectively, with iPhone 16 Pro Max offering the largest iPhone display ever. Both models have always-on 19.5:9 aspect ratio displays, with 460 ppi density from a (Pro) and (Pro Max) resolution. Both are 120 Hz, HDR10, with 1000 nits brightness typical and 2000 nits at peak.
Both Pro models come in four colors, the new Desert Titanium, Natural Titanium, White Titanium and Black Titanium, offering a lightweight, scratch-resistant exterior. The Desert Titanium color replaced the Blue Titanium color used on the iPhone 15 Pro and iPhone 15 Pro Max.
Hardware
The iPhone 16 Pro models are powered by the Apple A18 Pro chip, built using a second-generation 3-nanometer process (TSMC N3E), significantly enhancing performance, especially in AI-related tasks. This chip includes a 6-core CPU, 6-core GPU, and a 16-core Neural Engine with a speed of 35 trillion-operations-per-second that accelerates machine learning capabilities, allowing for seamless integration of Apple Intelligence features. Both models offer 8 GB of memory and storage options ranging from 128 GB (256 GB for Pro Max) to 1 TB.
All iPhone 16 models have an improved thermal design. The main logic board has been updated, centralizing chip placement and optimizing the surrounding architecture. The iPhone 16 Pro lineup maximizes thermal capacity with a machined chassis that uses 100 percent recycled aluminum, bonded to the titanium frame using solid state diffusion. This is combined with a graphite clad aluminum substructure. The new thermal architecture enables a 20 percent improvement in sustained gaming performance compared to the A17 Pro.
Every model in the iPhone 16 lineup has support for Wi-Fi 7 (802.11a/b/g/n/ac/ax/be). In a teardown by iFixit, the US model's modem was shown to be a Qualcomm X71 (SDX71M-000).
Camera
The iPhone 16 Pro introduces an upgraded camera system, with three rear cameras and a lidar scanner. It features "wide", "ultrawide" and "telephoto" lenses. The wide camera is 48 megapixels, with sensor-shift optical image stabilization (OIS) and dual-pixel phase detection autofocus (PDAF). The ultrawide camera is 48 MP with a 120-degree field of view, optimized for low-light conditions. A 5× optical zoom telephoto camera, which was previously exclusive to the iPhone 15 Pro Max, now comes standard on both models. In addition, video recording now supports 4K at 120 frames per second, offering the iPhone's highest resolution and frame rate combination yet and is the only iPhone to record in 4K in slow motion.
Camera control button
All iPhone 16 models now come with a new button called Camera Control. This button is on the right side of the device, and allows the user to open the camera app, switch between different camera controls and features, and taking photos and videos. The button can distinguish between light and hard presses. By pressing the button once, it opens the camera app. By lightly pressing it twice, it opens a small menu with different camera controls, such as zoom or tone, and if a user presses it hard once, it takes a photo. If a user holds it for a few seconds, it starts a video.
Software
One of the iPhone 16 Pro's features is its integration with Apple Intelligence, a suite of AI-driven capabilities. Apple Intelligence enhances Siri's functionality, improving natural language understanding and introduces generative features such as custom emojis and Visual Intelligence, which can analyze photos and identify objects in real-time.
Release and pricing
Pre-orders for iPhone 16 Pro and iPhone 16 Pro Max began on September 13, 2024, and they became available on September 20, 2024. The iPhone 16 Pro model starts at $999, while the Pro Max model starts at $1,199.
Availability by region
September 20, 2024
Australia
Austria
Bahrain
Brazil
Belgium
Canada
China
Croatia
Czech Republic
Denmark
Finland
France
Germany
Greece
Hong Kong
Hungary
India
Italy
Ireland
Japan
Luxembourg
Malaysia
Mexico
Netherlands
New Zealand
Norway
Oman
Poland
Portugal
Qatar
Saudi Arabia
Serbia
Singapore
Slovakia
South Africa
South Korea
Spain
Sweden
Switzerland
Taiwan
Thailand
Turkey
United Arab Emirates
United Kingdom
United States
September 27, 2024
Macao
Vietnam
October 18, 2024
Bangladesh
Israel
Philippines
Indonesian sales ban
On October 20, 2024, the Indonesian Ministry of Industry announced a formal ban on the sale and use of iPhone 16 models in Indonesia, citing that Apple has not fulfilled their promised investments in the country, and failing to meet the 40% local content requirement threshold for certification. Apple subsequently offered a $100 million investment in exchange for lifting of the ban, but the Ministry of Industry rejected this offer, stating that it "has not met principles of fairness" and demanded a larger amount, which later said to be at least $1 billion.
References
External links
– official website
Mobile phones introduced in 2024
Products introduced in 2024
Mobile phones with 4K video recording
Mobile phones with multiple rear cameras
Flagship smartphones | IPhone 16 Pro | [
"Technology"
] | 1,243 | [
"Flagship smartphones"
] |
77,830,283 | https://en.wikipedia.org/wiki/Pooling%20layer | In neural networks, a pooling layer is a kind of network layer that downsamples and aggregates information that is dispersed among many vectors into fewer vectors. It has several uses. It removes redundant information, reducing the amount of computation and memory required, makes the model more robust to small variations in the input, and increases the receptive field of neurons in later layers in the network.
Convolutional neural network pooling
Pooling is most commonly used in convolutional neural networks (CNN). Below is a description of pooling in 2-dimensional CNNs. The generalization to n-dimensions is immediate.
As notation, we consider a tensor , where is height, is width, and is the number of channels. A pooling layer outputs a tensor .
We define two variables called "filter size" (aka "kernel size") and "stride". Sometimes, it is necessary to use a different filter size and stride for horizontal and vertical directions. In such cases, we define 4 variables .
The receptive field of an entry in the output tensor are all the entries in that can affect that entry.
Max pooling
Max Pooling (MaxPool) is commonly used in CNNs to reduce the spatial dimensions of feature maps.
Definewhere means the range . Note that we need to avoid the off-by-one error. The next input isand so on. The receptive field of is , so in general,If the horizontal and vertical filter size and strides differ, then in general,More succinctly, we can write .
If is not expressible as where is an integer, then for computing the entries of the output tensor on the boundaries, max pooling would attempt to take as inputs variables off the tensor. In this case, how those non-existent variables are handled depends on the padding conditions, illustrated on the right.
Global Max Pooling (GMP) is a specific kind of max pooling where the output tensor has shape and the receptive field of is all of . That is, it takes the maximum over each entire channel. It is often used just before the final fully connected layers in a CNN classification head.
Average pooling
Average pooling (AvgPool) is similarly definedGlobal Average Pooling (GAP) is defined similarly to GMP. It was first proposed in Network-in-Network. Similarly to GMP, it is often used just before the final fully connected layers in a CNN classification head.
Interpolations
There are some interpolations of max pooling and average pooling.
Mixed Pooling is a linear sum of maxpooling and average pooling. That is,
where is either a hyperparameter, a learnable parameter, or randomly sampled anew every time.
Lp Pooling is like average pooling, but uses Lp norm average instead of average:where is the size of receptive field, and is a hyperparameter. If all activations are non-negative, then average pooling is the case of , and maxpooling is the case of . Square-root pooling is the case of .
Stochastic pooling samples a random activation from the receptive field with probability . It is the same as average pooling in expectation.
Softmax pooling is like maxpooling, but uses softmax, i.e. where . Average pooling is the case of , and maxpooling is the case of
Local Importance-based Pooling generalizes softmax pooling by where is a learnable function.
Other poolings
Spatial pyramidal pooling applies max pooling (or any other form of pooling) in a pyramid structure. That is, it applies global max pooling, then applies max pooling to the image divided into 4 equal parts, then 16, etc. The results are then concatenated. It is a hierarchical form of global pooling, and similar to global pooling, it is often used just before a classification head.
Region of Interest Pooling (also known as RoI pooling) is a variant of max pooling used in R-CNNs for object detection. It is designed to take an arbitrarily-sized input matrix, and output a fixed-sized output matrix.
Covariance pooling computes the covariance matrix of the vectors which is then flattened to a -dimensional vector . Global covariance pooling is used similarly to global max pooling. As average pooling computes the average, which is a first-degree statistic, and covariance is a second-degree statistic, covariance pooling is also called "second-order pooling". It can be generalized to higher-order poolings.
Blur Pooling means applying a blurring method before downsampling. For example, the Rect-2 blur pooling means taking an average pooling at , then taking every second pixel (identity with ).
Vision Transformer pooling
In Vision Transformers (ViT), there are the following common kinds of poolings.
BERT-like pooling uses a dummy [CLS] token ("classification"). For classification, the output at [CLS] is the classification token, which is then processed by a LayerNorm-feedforward-softmax module into a probability distribution, which is the network's prediction of class probability distribution. This is the one used by the original ViT and Masked Autoencoder.
Global average pooling (GAP) does not use the dummy token, but simply takes the average of all output tokens as the classification token. It was mentioned in the original ViT as being equally good.
Multihead attention pooling (MAP) applies a multiheaded attention block to pooling. Specifically, it takes as input a list of vectors , which might be thought of as the output vectors of a layer of a ViT. It then applies a feedforward layer on each vector, resulting in a matrix . This is then sent to a multiheaded attention, resulting in , where is a matrix of trainable parameters. This was first proposed in the Set Transformer architecture.
Later papers demonstrated that GAP and MAP both perform better than BERT-like pooling.
Graph neural network pooling
In graph neural networks (GNN), there are also two forms of pooling: global and local. Global pooling can be reduced to a local pooling where the receptive field is the entire output.
Local pooling: a local pooling layer coarsens the graph via downsampling. Local pooling is used to increase the receptive field of a GNN, in a similar fashion to pooling layers in convolutional neural networks. Examples include k-nearest neighbours pooling, top-k pooling, and self-attention pooling.
Global pooling: a global pooling layer, also known as readout layer, provides fixed-size representation of the whole graph. The global pooling layer must be permutation invariant, such that permutations in the ordering of graph nodes and edges do not alter the final output. Examples include element-wise sum, mean or maximum.
Local pooling layers coarsen the graph via downsampling. We present here several learnable local pooling strategies that have been proposed. For each cases, the input is the initial graph is represented by a matrix of node features, and the graph adjacency matrix . The output is the new matrix of node features, and the new graph adjacency matrix .
Top-k pooling
We first set
where is a learnable projection vector. The projection vector computes a scalar projection value for each graph node.
The top-k pooling layer can then be formalised as follows:
where is the subset of nodes with the top-k highest projection scores, denotes element-wise matrix multiplication, and is the sigmoid function. In other words, the nodes with the top-k highest projection scores are retained in the new adjacency matrix . The operation makes the projection vector trainable by backpropagation, which otherwise would produce discrete outputs.
Self-attention pooling
We first set
where is a generic permutation equivariant GNN layer (e.g., GCN, GAT, MPNN).
The Self-attention pooling layer can then be formalised as follows:
where is the subset of nodes with the top-k highest projection scores, denotes element-wise matrix multiplication.
The self-attention pooling layer can be seen as an extension of the top-k pooling layer. Differently from top-k pooling, the self-attention scores computed in self-attention pooling account both for the graph features and the graph topology.
History
In early 20th century, neuroanatomists noticed a certain motif where multiple neurons synapse to the same neuron. This was given a functional explanation as "local pooling", which makes vision translation-invariant. (Hartline, 1940) gave supporting evidence for the theory by electrophysiological experiments on the receptive fields of retinal ganglion cells. The Hubel and Wiesel experiments showed that the vision system in cats is similar to a convolutional neural network, with some cells summing over inputs from the lower layer. See (Westheimer, 1965) for citations to these early literature.
During the 1970s, to explain the effects of depth perception, some such as (Julesz and Chang, 1976) proposed that the vision system implements a disparity-selective mechanism by global pooling, where the outputs from matching pairs of retinal regions in the two eyes are pooled in higher order cells. See for citations to these early literature.
In artificial neural networks, max pooling was used in 1990 for speech processing (1-dimensional convolution).
See also
Convolutional neural network
Subsampling
Image scaling
Feature extraction
Region of interest
Graph neural network
References
Neural network architectures
Computer vision
Computational neuroscience | Pooling layer | [
"Engineering"
] | 2,044 | [
"Artificial intelligence engineering",
"Packaging machinery",
"Computer vision"
] |
77,830,504 | https://en.wikipedia.org/wiki/Hedonic%20scale | The hedonic scale is a sensory evaluation tool used to measure the degree of pleasure or liking of a product or service. The scale usually consists of 9 levels ranging from 1 to 9, or "dislike extremely" to "like extremely".
The hedonic scale is widely used for consumer acceptance testing.
See also
JAR scale
References
Product testing
Psychophysics | Hedonic scale | [
"Physics"
] | 73 | [
"Psychophysics",
"Applied and interdisciplinary physics"
] |
77,830,623 | https://en.wikipedia.org/wiki/Just-About-Right%20scale | The Just-About-Right scale (JAR scale), is a sensory evaluation tool used to measure the intensity of a particular attribute or characteristic of a product or service. The JAR scale typically consists of 5 levels ranging from "Much too little" to "Much too much."
The JAR scale focuses on specific attributes of a product such as sweetness, saltiness, texture, etc., or service such as expediency, cost, etc.
The JAR scale is criticized for measuring attribute intensity and acceptability simultaneously.
See also
Hedonic scale
References
Product testing
Psychophysics | Just-About-Right scale | [
"Physics"
] | 118 | [
"Psychophysics",
"Applied and interdisciplinary physics"
] |
77,831,713 | https://en.wikipedia.org/wiki/Wincenty%20Witos%20Monument | Wincenty Witos Monument (Polish: Pomnik Wincentego Witosa) is a monument in Warsaw, Poland, placed at the Three Crosses Square, within the Downtown district. It consists of a bronze statue of Wincenty Witos, a statesman and politician, who was the Prime Minister of Poland from 1920 to 1921, in 1923, and in 1926. It was designed by Marian Konieczny, and unveiled on 22 September 1985.
History
The monument was designed by Marian Konieczny, and unveiled on 22 September 1985.
Characteristics
The monument is placed at the Three Crosses Square, within the Downtown district. It consists of a bronze statue of Wincenty Witos, a statesman and politician, who was the Prime Minister of Poland from 1920 to 1921, in 1923, and in 1926. The figure wears a suit and a winter coat, and holds a book in the left hand, and a hat, in the right hand. It is placed on a large granite pedestal. Its front features a Polish inscription that reads "…a Polska winna trwać wiecznie" (transaction: and Poland should last forever), a Witos's quote, while the back, "Wielkiemu synowi polskiej wsi – Naród" (translation: To the great son of Polish countryside, the Nation). It has the total height of 6 m, with the statue being half of that.
References
Monuments and memorials in Warsaw
1985 establishments in Poland
Buildings and structures completed in 1985
1985 sculptures
Outdoor sculptures in Warsaw
Statues of men in Poland
Statues of prime ministers
Bronze sculptures in Poland
Granite sculptures in Poland
Śródmieście Południowe
Colossal statues | Wincenty Witos Monument | [
"Physics",
"Mathematics"
] | 343 | [
"Quantity",
"Colossal statues",
"Physical quantities",
"Size"
] |
77,832,351 | https://en.wikipedia.org/wiki/Physics%20education%20in%20Hong%20Kong | Physics education in Hong Kong is carried both at high schools and universities.
High schools
In Hong Kong, physics is a subject for public examination. Local students in Form 6 take the public exam of Hong Kong Diploma of Secondary Education (HKDSE).
Compare to the other syllabus include GCSE, GCE etc. which learn wider and broader on different topics, the Hong Kong syllabus is learning more deeply and more challenges with calculations. Topics are narrowed down to a smaller amount compared to the A-level due to the insufficient teaching hours at secondary schools in Hong Kong, which include temperature, heat, internal energy, change of state, gases, position, motion, force, projectile motion, work, energy, power, momentum, uniform circular motion, gravitation, wave, light, sound, electrostatics, circuits, electromagnetism, radiation, radioactivity, atomic model, nuclear energy, universe, astronomy, stars, Rutherford model, photoelectric effect, Bohr model, particles, nanoscopic scale, building, transportation, renewable energy sources, eye, ear, non-ionizing radiation and ionizing radiation etc.
Some schools only allow students choose physics as elective subject since Form 4, some schools provide physics compulsory curriculum in Form 3 and then allow students to choose in Form 4, and some other schools allow students choose physics as elective subject since Form 3. Also, most schools use English language as the medium of instruction for physics, whereas a few of the schools use Chinese language as the medium of instruction for physics.
Other than having lectures in classrooms or laboratories, schools in Hong Kong organise outside-school activities to motivate students learning Physics.
Universities
Pure Physics major programmes are provided in the Chinese University of Hong Kong (CUHK), Hong Kong University of Science and Technology (HKUST) and University of Hong Kong (HKU). Topics include engineering physics, mechanics, thermodynamics, fluids, wave, optics, modern physics, laboratory, heat, electromagnetism, quantitative methods, computational physics, astronomy, astrophysics, classical mechanics, quantum mechanics, quantum information, statistical physics, theoretical physics, computer simulation, soft matter, practical electronics, contemporary physics, instrumentation, statistical mechanics, solid state physics, meteorology, nanoscience, optical physics, theory of relativity and particle physics etc.
There are different approaches of delivering physics lectures in different universities in Hong Kong. In CUHK, most relevant knowledge including quantitative methods and computer simulation are learnt in the Department of Physics, which may let the students learn deeper into the concept that applied to the physics problems, whereas in HKUST, quantitative methods and computer simulation are learnt by students in the courses delivered by Department of Mathematics and Department of Computer Science respectively which allow the students to learn boarder with knowledge of different aspects.
There are also Enrichment Stream in Theoretical Physics offered by CUHK and International Research Enrichment Track offered by HKUST. In that stream, additional topics include astrophysics, particle physics, computational physics, and quantum physics. The practices of solving theoretical systems and the discussions of physical insight are very in-depth, which promote the graduates into a high level of the understanding of physics. However, the working opportunity for graduates with theoretical background in Hong Kong is too narrow. Most graduates pursue further studies overseas or become teachers.
Moreover, Applied Physics major programmes are offered only in most other universities in Hong Kong.
References
Hong Kong
Science and technology in Hong Kong
Education in Hong Kong | Physics education in Hong Kong | [
"Physics"
] | 709 | [
"Applied and interdisciplinary physics",
"Physics education"
] |
77,833,472 | https://en.wikipedia.org/wiki/Camizestrant | Camizestrant is an investigational new drug that is being evaluated to treat breast cancer. It is an estrogen receptor alpha antagonist and a selective estrogen receptor degrader (SERD).
References
Selective estrogen receptor degraders
Antineoplastic drugs
Amines
Azetidines
Isoquinolines
Pyrazolones
Pyridines
Trifluoromethyl compounds | Camizestrant | [
"Chemistry"
] | 82 | [
"Pharmacology",
"Functional groups",
"Medicinal chemistry stubs",
"Amines",
"Pharmacology stubs",
"Bases (chemistry)"
] |
77,833,581 | https://en.wikipedia.org/wiki/Ibcasertib | Ibcasertib is an investigational new drug that is being evaluated to treat small-cell lung cancer. Ibcasertib inhibits several angiogenesis-related kinases, including VEGFR1, VEGFR2, VEGFR3, PDGFRα, and c-Kit, as well as the mitosis-related kinase Aurora B and the chronic inflammation-related kinase CSF-1R.
References
Amides
Anilines
Antineoplastic drugs
Ethers
Naphthalenes
Quinolines
Anilides | Ibcasertib | [
"Chemistry"
] | 112 | [
"Pharmacology",
"Functional groups",
"Medicinal chemistry stubs",
"Organic compounds",
"Ethers",
"Pharmacology stubs",
"Amides"
] |
77,833,708 | https://en.wikipedia.org/wiki/Milademetan | Milademetan is an investigational new drug that is being evaluated to treat liposarcoma. It is a MDM2 inhibitor.
References
Antineoplastic drugs
Amides
Cyclohexanes
Indoles
Pyrans
Pyrrolidines
Spiro compounds
Pyridines
Chloroarenes
Fluoroarenes | Milademetan | [
"Chemistry"
] | 71 | [
"Pharmacology",
"Functional groups",
"Medicinal chemistry stubs",
"Organic compounds",
"Pharmacology stubs",
"Amides",
"Spiro compounds"
] |
77,833,801 | https://en.wikipedia.org/wiki/Reldesemtiv | Reldesemtiv is an investigational new drug that is being evaluated to treat amyotrophic lateral sclerosis. It is a troponin activator.
References
Amides
Cyclobutanes
Pyridines
Pyrimidines
Pyrroles
Fluoroarenes | Reldesemtiv | [
"Chemistry"
] | 64 | [
"Pharmacology",
"Functional groups",
"Medicinal chemistry stubs",
"Pharmacology stubs",
"Amides"
] |
77,834,120 | https://en.wikipedia.org/wiki/Valiltramiprosate | Valiltramiprosate is an investigational new drug that is being evaluated to treat early Alzheimer's disease. It is an amyloid precursor protein antagonist.
References
Sulfonic acids
Carboxamides
Amines
Amino acids
Isopropyl compounds | Valiltramiprosate | [
"Chemistry"
] | 54 | [
"Pharmacology",
"Biomolecules by chemical classification",
"Functional groups",
"Medicinal chemistry stubs",
"Amines",
"Amino acids",
"Sulfonic acids",
"Pharmacology stubs",
"Bases (chemistry)"
] |
63,365,963 | https://en.wikipedia.org/wiki/Columba%20association | In astronomy, the Columba association is a nearby Myr old stellar association. The association is named after the constellation Columba which contains many of the stars first recognized in the group.
Special interest
Stars in young associations are a popular target for professional astronomers. The stars are often surrounded by circumstellar disks, discs of dust and other planet forming matter around a young star, and young planets that still glow in the infrared spectrum, which makes it easier to directly image, using the light reflected off of the planets to obtain an image of the planets. The most famous star in the Columba association is which has four directly imaged planets.
The group was at first not recognized as an individual group, but stars within the group were first assigned to the Great Austral Young Association (GAYA), because it showed similar movement and distance compared with two nearby groups. Only later it became clear that GAYA is subdivided into three groups: the Tucana-Horologium association, the Carina association and the Columba association.
The brightest star in the association is the massive star HD 32309, with a spectral type of B9Vann and an apparent magnitude of 4.90 . The association also contains several A-type and F-type stars, such as Omega Aurigae, HR 8799, 26 Geminorum and AS Columbae. It also contains several other variable stars, such as V1358 Orionis, RT Pictoris, DK Leonis, V909 Orionis and GJ 1284. The stars HD 30447 and HD 35847 are members of the group with directly imaged debris disks.
See also
List of nearby stellar associations and moving groups
Argus Association
TW Hydrae association
Footnotes
References
Stellar associations
Columba (constellation) | Columba association | [
"Astronomy"
] | 372 | [
"Columba (constellation)",
"Constellations"
] |
63,366,055 | https://en.wikipedia.org/wiki/Green%20rush | The Green Rush (2012–present) is an ongoing global economic event that began on December 6, 2012, when cannabis was legalized in the US state of Washington; Colorado's legalization took effect four days later. While still illegal federally in the United States, the actions of these two state governments signaled the opening of a market projected to be worth globally by 2027. As of 2019 the cannabis industry had created over 250,000 jobs. However, cannabis companies have been a mixed investment success, with many experiencing plunging stock prices, massive layoffs, and failure to meet investor expectations.
Etymology
According to Maximum Yield:
The "green rush" can also be used to characterize the movement of capital and people into territories and markets that have legalized cannabis.
History
The economic viability of the cannabis marketplace began to erode in the United States in 1937 when the Marihuana Tax Act was passed, prohibiting the production of cannabis in addition to hemp. Later the United Nations conventions on drug control include the Single Convention on Narcotic Drugs of 1961, effectively ended the legal international trade in medicinal and recreational cannabis. These reforms were largely manifested by public fear campaigns that included the public exhibitions of films such as Reefer Madness (1936) that were supported by Federal Bureau of Narcotics commissioner Harry J. Anslinger and his contemporaries.
It was not until the early 1990s that events such as Seattle Hempfest began public education campaigns to reverse the public perception about the restoration and viability of a medicinal and recreational marijuana marketplace. Activist efforts such as these have spearheaded the green rush which has contributed to the legalization of cannabis in 5 countries; led to the legalization of cannabis for recreational production, sale and consumption in 11 U.S. states; and also inspired medicinal cannabis exchanges in 33 states as of January 2020.
These reforms have created substantial economic activity not only related to growing and selling cannabis, but have facilitated the lesser known ancillary market in the cannabis industry that provides opportunity in other sectors such as packaging, marketing, software, media, finance, and real estate.
2023 Oklahoma State Question 820 was rejected by over 60% of voters, the largest margin of defeat for a legalization measure since the beginning of the green rush.
Licensing
In most US & Canadian jurisdictions cannabis business owners are required to have a license to legally produce, modify, transport and/or sell cannabis products. The same has held true of Uruguay's emerging market. These licensing systems are regulatory in nature, designed to assure quality standards to protect consumers and assure that proper taxes are collected from the business entity. The licensing system is also designed to protect society from illicit acts such as selling cannabis to minors and money laundering. In the United States, state licensing schemes are modeled under Department of Justice guidance issued under the Cole Memorandum during the Obama administration. Canada has implemented similar rules.
Most jurisdictions have requirements termed "green-zones" which require that cannabis businesses operate a certain distance from schools, churches, and other family facilities. These restrictions makes green-zone real estate both highly valuable and highly sought after; In many jurisdictions an application for a license must include some kind of link to properly zoned real estate.
Upon voter-sanctioned legalization each jurisdiction has implemented its own unique systems for applicants seeking to open licensed cannabis businesses. The first two examples were Washington State and Colorado. In Washington 1175 applicants applied for licenses with 334 qualified applicants being selected in a lottery. Colorado opted to issue 348 licenses to existing medical marijuana businesses in good standing. These initial systems left many potentially qualified applicants without a means to obtain a license. The cap on the number of licenses and the use of a lottery to award them resulted in highly disparate outcomes among businesses who won local lotteries.
Secondary market
License issuance is controlled and regulated by governments which in many cases have allowed for their transfer. Due to the limited supply of licenses and high number of organizations seeking to obtain them a secondary market has emerged for licenses. In some areas a license can command a price in the 10s of millions of dollars. As a result, several digital marketplaces have created niches for themselves allowing individuals to list and buy licenses from other individuals.
MSOs
A Multi-State Operator, or MSO, is a term unique to the United States that refers to a cannabis company that holds licenses or otherwise operates in multiple states. However, since the emergence of the Canadian Marketplace many US MSOs have traded on the Canadian marketplace, and consequently many Canadian companies have sought licenses and IPOs in the United States.
Stock markets
Marijuana stocks became popular following the first phases of legalization in the United States, with mixed success. Many initial cannabis offerings were traded on the OTC market as early as 2012 but have subsequently failed. In 2016 both Canadian and US based stocks began trading on the Toronto Stock Exchange. Canopy Growth was the first federally regulated, licensed, publicly traded cannabis producer in North America; it began trading on the Toronto Stock Exchange as WEED in August 2016. The first cannabis IPO took place on July 19, 2018. A Canadian-based company, Tilray (TLRY), began publicly trading on Nasdaq at $17 per share. In many cases cannabis stocks have fallen in price over 80% amidst massive layoffs and failure to meet investor expectations. The Global Cannabis Stock index, a measure of cannabis stock value, fell from a high of in January 2017 to a low of in March 2020, although it had reclaimed some territory to by August 2020.
Black market
Since the inception of prohibition, a black market for cannabis has existed. Estimates say the black market makes up 87% of all sales, netting over 40 billion dollars in the US alone, according to a 2016 study. The black market has created additional issues for cannabis regulators and legal businesses owners alike. Black Market operators have been known to open illegal store fronts posing as legal operators to unwary consumers, an activity that for the moment has overwhelmed law enforcement's ability to regulate these illicit businesses. These operators also pose issues for legal operators because illegal dispensaries are able to offer consumers cannabis products at lower prices than their regulated, tax-paying, legal counterparts. A 2021 study of Washington state showed that by enforcing the regulations against unlicensed retailers the state had almost eliminated the black market for sales to consumers.
Vape crisis
Because of the nature of the black market some operators have been found to be selling adulterated electronic cigarettes attuned to cannabis, that allow cartridges of oil derived from the cannabis plant to be heated and inhaled by the user. In some cases these illegally-manufactured cartridges have been found to have 7000 times the legal limit of pesticides. These illicit products led to the 2019–20 vaping lung illness outbreak which hospitalized many unwary consumers, including many minors, and in some cases resulted in permanent injuries and fatalities. While efforts are underway by law enforcement to crack down on the illicit trade, the issue is ongoing as of 2020.
Controversy
United States
Social equity
While racial and economic minorities were often the most persecuted groups under prohibition, the primary make up of the marijuana industry leadership is white males, who compose over 70% of cannabis executives. The primary barrier to both minorities and women has been access to capital needed to start-up cannabis businesses. This has resulted in many jurisdictions' implementing social equity laws to combat this economic disparity, with mixed results.
Banking
Currently in the US cannabis companies cannot use traditional banking. This has effectively made cannabis in the US a cash-only business. Commentators have claimed that by not allowing banking, the government has set the stage for money laundering and other forms of crime. Currently all legislation set to fix cannabis banking issues has failed to pass the Senate.
Federal taxation
Internal Revenue Code section 280e is a law created during the Reagan administration designed to prevent deductions of business exemptions for scheduled substances. Because marijuana is still a Schedule 1 substance in the US, license holders have been subject to a higher tax burden than a normal business. To many business owners this obscure tax law has been made known to them in the form of a letter from the IRS requesting substantial back tax for misappropriated deductions on their businesses.
Canada
Dispensaries
The Canadian government has been slow to license enough dispensaries to meet consumer demand and cultivator supply. This has created issues both for large cannabis producers and for consumers. In an effort to fix the disparity, the Canadian government implemented what is known as Cannabis 2.0; however, the dispensary issue has yet to be addressed by the Canadian government, leading to the resurgence of the black market.
See also
Decriminalization of non-medical cannabis in the United States
References
External links
"I-502 data"
"Cole Memorandum"
Cannabis law reform
Drug control law
Cannabis in the United States
Cannabis in Canada | Green rush | [
"Chemistry"
] | 1,787 | [
"Drug control law",
"Regulation of chemicals"
] |
63,367,384 | https://en.wikipedia.org/wiki/Algorithmic%20Geometry | Algorithmic Geometry is a textbook on computational geometry. It was originally written in the French language by Jean-Daniel Boissonnat and Mariette Yvinec, and published as Géometrie algorithmique by Edusciences in 1995. It was translated into English by Hervé Brönnimann, with improvements to some proofs and additional exercises, and published by the Cambridge University Press in 1998.
Topics
The book covers the theoretical background and analysis of algorithms in computational geometry, their implementation details, and their applications. It is grouped into five sections, the first of which covers background material on the design and analysis of algorithms and data structures, including computational complexity theory, and techniques for designing randomized algorithms. Its subsequent sections each consist of a chapter on the mathematics of a subtopic in this area, presented at the level of detail needed to analyze the algorithms, followed by two or three chapters on algorithms for that subtopic.
The topics presented in these sections and chapters include convex hulls and convex hull algorithms, low-dimensional randomized linear programming, point set triangulation for two- and three-dimensional data, arrangements of hyperplanes, of line segments, and of triangles, Voronoi diagrams, and Delaunay triangulations.
Audience and reception
The book can be used as a graduate textbook, or as a reference for computational geometry research. Reviewer Peter McMullen calls it "a welcome addition to the shelves of anyone interested in algorithmic geometry".
References
Computational geometry
Mathematics textbooks
1995 non-fiction books
1998 non-fiction books | Algorithmic Geometry | [
"Mathematics"
] | 316 | [
"Computational geometry",
"Computational mathematics"
] |
63,368,344 | https://en.wikipedia.org/wiki/Marie%20Rognes | Marie Elisabeth Rognes (born 7 October 1982) is a Norwegian applied mathematician specializing in scientific computing and numerical methods for partial differential equations. She works at the Simula Research Laboratory, as one of their chief research scientists.
Education and career
Rognes was a student in applied mathematics at the University of Oslo, earning a master's degree in 2005 and completing a Ph.D. in 2009. Her dissertation, Mixed finite element methods with applications to viscoelasticity and gels, was jointly supervised by Ragnar Winther and Hans Petter Langtangen.
After postdoctoral research at the University of Minnesota and the Simula Research Laboratory, she joined the University of Oslo as a lecturer in 2012, and in the same year became a senior researcher for Simula Research. She remained affiliated on a part-time basis with the University of Oslo until 2016, when she became a chief research scientist for Simula Research.
Recognition
Rognes became one of 20 founding members of the Young Academy of Norway in 2015. In the same year she was part of a team that won the J. H. Wilkinson Prize for Numerical Software, given every four years at the International Congress on Industrial and Applied Mathematics. The award cited their work on dolfin-adjoint, a software package for adjoint and tangent linear equations.
In 2018 she was the winner of the Royal Norwegian Society of Sciences and Letters Prize for Young Researchers in the Natural Sciences.
References
External links
Home page
1982 births
Living people
Norwegian mathematicians
Norwegian women mathematicians
Applied mathematicians
University of Oslo alumni
Academic staff of the University of Oslo | Marie Rognes | [
"Mathematics"
] | 320 | [
"Applied mathematics",
"Applied mathematicians"
] |
63,369,842 | https://en.wikipedia.org/wiki/Protocol%20ossification | Protocol ossification is the loss of flexibility, extensibility and evolvability of network protocols. This is largely due to middleboxes that are sensitive to the wire image of the protocol, and which can interrupt or interfere with messages that are valid but which the middlebox does not correctly recognise. This is a violation of the end-to-end principle. Secondary causes include inflexibility in endpoint implementations of protocols.
Ossification is a major issue in Internet protocol design and deployment, as it can prevent new protocols or extensions from being deployed on the Internet, or place strictures on the design of new protocols; new protocols may have to be encapsulated in an already-deployed protocol or mimic the wire image of another protocol. Because of ossification, the Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) are the only practical choices for transport protocols on the Internet, and TCP itself has significantly ossified, making extension or modification of the protocol difficult.
Recommended methods of preventing ossification include encrypting protocol metadata, and ensuring that extension points are exercised and wire image variability is exhibited as fully as possible; remedying existing ossification requires coordination across protocol participants. QUIC is the first IETF transport protocol to have been designed with deliberate anti-ossification properties.
History
Significant ossification had set in on the Internet by 2005, with analyses of the problem also being published in that year; suggests that ossification was a consequence of the Internet attaining global scale and becoming the primary communication network.
Multipath TCP was the first extension to a core Internet protocol to deeply confront protocol ossification during its design.
The IETF created the Transport Services (taps) working group in 2014. It has a mandate to mitigate ossification at the transport protocol layer.
QUIC is the first IETF transport protocol to deliberately minimise its wire image to avoid ossification.
The Internet Architecture Board identified design considerations around the exposure of protocol information to network elements as a "developing field" in 2023.
Causes
The primary cause of protocol ossification is middlebox interference, invalidating the end-to-end principle. Middleboxes may entirely block unknown protocols or unrecognised extensions to known protocols, interfere with extension or feature negotiation, or perform more invasive modification of protocol metadata. Not all middlebox modifications are necessarily ossifying; of those which are potentially harmful, they are disproportionately towards the network edge. Middleboxes are deployed by network operators unilaterally to solve specific problems, including performance optimisation, security requirements (e.g., firewalls), network address translation or enhancing control of networks. These middlebox deployments provide localised short-term utility but degrade the global long-term evolvability of the Internet in a manifestation of the tragedy of the commons.
Changes to a protocol must be tolerated by all on-path intermediaries; if wide Internet deployment of the change is desired, then this extends to a large portion of intermediaries on the Internet. A middlebox must tolerate widely-used protocols as they were being used at the time of its deployment, but is liable not to tolerate new protocols or changes to extant ones, effectively creating a vicious cycle as novel wire images cannot gain wide enough deployment to make middleboxes tolerate the new wire image across the entire Internet. Even all participants tolerating the protocol is no guarantee of use: in the absence of a negotiation or discovery mechanism, the endpoints may default to a protocol that is considered more reliable.
Beyond middleboxes, ossification can also be caused by insufficient flexibility within the endpoint's implementation. Operating system kernels are slow to change and deploy, and protocols implemented in hardware can also inappropriately fix protocol details. A widely-used application programming interface (API) that makes assumptions about the operation of underlying protocols can hinder the deployment of protocols that do not share those assumptions.
Prevention and remediation
The Internet Architecture Board recommended in 2019 that implicit signals to observers should be replaced with signals deliberately intended for the consumption of those observers, and signals not intended for their consumption should not be available to them (e.g., by encryption); and also that the protocol metadata should be integrity protected so that it cannot be modified by middleboxes. However, even fully encrypted metadata may not entirely prevent ossification in the network, as the wire image of a protocol can still show patterns that come to be relied upon. Network operators use metadata for a variety of benign management purposes, and Internet research is also informed by data gathered from protocol metadata; a protocol's designer must balance ossification resistance against observability for operational or research needs. provides further guidance on these considerations: disclosure of information by a protocol to the network should be intentional, performed with the agreement of both recipient and sender, authenticated to the degree possible and necessary, only acted upon to the degree of its trustworthiness, and minimised and provided to a minimum number of entities.
Active use of extension points is required if they are not to ossify. Reducing the number of extension points, documenting invariants that protocol participants can rely on as opposed to incidental details that must not be relied upon, and prompt detection of issues in deployed systems can assist in ensuring active use. However, even active use may only exercise a narrow portion of the protocol and ossification can still occur in the parts that remain invariant in practice despite theoretical variability. "Greasing" an extension point, where some implementations indicate support for non-existent extensions, can ensure that actually-existent-but-unrecognised extensions are tolerated (cf. chaos engineering). HTTP headers are an example of an extension point that has successfully avoided significant ossification, as participants will generally ignore unrecognised headers.
A new protocol may be designed to mimic the wire image of an existing ossified protocol; alternatively, a new protocol may be encapsulated within an existing, tolerated protocol. A disadvantage of encapsulation is that there is typically overhead and redundant work (e.g., outer checksums made redundant by inner integrity checks).
Besides middleboxes, other sources of ossification can also be resisted. User-space implementation of protocols can lead to more rapid evolution. If the new protocol is encapsulated in UDP, then user-space implementation is possible. Where support for protocols is uncertain, participants may simultaneously try alternative protocols, at the cost of increasing the amount of data sent.
With sufficient effort and coordination, ossification can be directly reversed. A flag day, where protocol participants make changes in concert, can break the vicious cycle and establish active use. This approach was used to deploy EDNS, which had formerly not been tolerated by servers.
Examples
The Transmission Control Protocol has suffered from ossification. One measurement found that a third of paths across the Internet encounter at least one intermediary that modifies TCP metadata, and 6.5% of paths encounter harmful ossifying effects from intermediaries. Extensions to TCP have been affected: the design of MPTCP was constrained by middlebox behaviour, and the deployment of TCP Fast Open has been likewise hindered.
The Stream Control Transmission Protocol has been little-deployed on the Internet due to intolerance from middleboxes, and also due to the very widespread BSD sockets API ill-fitting its capabilities. In practice, TCP and UDP are the only usable Internet transport protocols.
Transport Layer Security (TLS) has experienced ossification. TLS was the original context for the introduction of greasing extension points. TLS 1.3, as originally designed, proved undeployable on the Internet: middleboxes had ossified the protocol's version parameter. This was discovered late in the protocol design process, during experimental deployments by web browsers. As a result, version 1.3 mimics the wire image of version 1.2.
QUIC has been specifically designed to be deployable, evolvable and to have anti-ossification properties; it is the first IETF transport protocol to deliberately minimise its wire image for these ends. It is greased, it has protocol invariants explicitly specified, it is encapsulated in UDP, and its protocol metadata is encrypted. Still, applications using QUIC must be prepared to fall back to other protocols, as UDP is blocked by some middleboxes.
See also
Backward compatibility
Collective action problem
De facto standard
Forward compatibility
Interoperability
Hyrum's law
Network effect
Robustness principle
Vendor lock-in
References
Bibliography
Further reading
Tragedy of the commons | Protocol ossification | [
"Mathematics"
] | 1,803 | [
"Game theory",
"Tragedy of the commons"
] |
63,370,948 | https://en.wikipedia.org/wiki/LMS%20Journal%20of%20Computation%20and%20Mathematics | LMS Journal of Computation and Mathematics was a peer-reviewed online mathematics journal covering computational aspects of mathematics published by the London Mathematical Society. The journal published its first article in 1998 and ceased operation in 2017. An open access archive of the journal is maintained by Cambridge University Press.
Abstracting and indexing
The journal is abstracted and indexed in MathSciNet, Scopus, and Zentralblatt MATH.
References
External links
English-language journals
Hybrid open access journals
Mathematics education in the United Kingdom
Computational mathematics journals | LMS Journal of Computation and Mathematics | [
"Mathematics"
] | 105 | [
"Computational mathematics",
"Computational mathematics journals"
] |
63,371,137 | https://en.wikipedia.org/wiki/Pyrocene | Pyrocene is a proposed term for a new geologic epoch or age characterized by the influence of human-caused fire activity on Earth. The concept focuses on the many ways humans have applied and removed fire from the Earth, including the burning of fossil fuels and the technologies that have enabled people to leverage their influence and become the dominant species on the planet. The Pyrocene offers a fire-centric perspective on human history that is an alternative to or complementary term for the Anthropocene. Like the Anthropocene, the concept suggests that human activity has shaped the Earth's geology and identifies fire as humanity's primary tool for shaping the planet and its environment.
Pyrocene was first proposed by environmental historian Stephen J. Pyne in 2015. Since that time, it has been adopted by journalists and scholars in the fields of wildland fire, ecology, and environmental policy focused on the impacts of climate change and increased risk of wildfires around the globe. This research has focused on extreme wildfires in Hawaii, California, Spain, Portugal, Romania, Australia, and Canada. It has relied on the concept of Pyrocene to highlight how climate change, land-use changes, and direct human ignition have increased the frequency and intensity of these conflagrations.
Etymology
The word Pyrocene is formed from two Ancient Greek words. Pyros (; ) is the Greek word for fire while "Cene" coming from the word kainós () means "new". The concept is that this epoch is "entirely new". The suffix '-cene' is used in several epochs of geologic Era.
Overview of the concept
The concept of the Pyrocene argues that humanity's collective fire practices have become an informing presence and a geological force on Earth. Fire practices include all those activities that start and stop fires among living biomass, but also those that involve fossil biomass and those pyrotechnologies that enable people to leverage their influence.
The foundational premise suggests that humanity and fire formed an alliance that increased the range and power of each. While fire has been on Earth for over 420 million years, as long as terrestrial plants (Silurian-Devonian terrestrial revolution), humanity has altered its regimes and expanded it into a planetary presence. In return, fire has enabled and accompanied humans to every landscape on Earth and even the Moon. Humanity enjoys a species monopoly over fire's manipulation, establishing it as the keystone species for fire on Earth and making fire its unique ecological signature.
Together, humans and fire have upset biogeochemical cycles, including carbon, rewired energy flows, and, through the accumulation of emitted greenhouse gases into the atmosphere, perturbed global climate to such an extent that climate history has become a subnarrative of fire history.
According to Pyne's concept of the Pyrocene, there have been three kinds of fire. The first kind of fire was natural fire, which began with the evolution of plants. The second kind of fire was human fire, which the species domesticated for heat, light, cooking, and the control of landscapes. The third kind of fire involves extracting and burning fossil fuels through chemical combustion and industrial machinery. This third kind of fire has created by-products in the form of pollution and greenhouse gasses on a scale that have overwhelmed the atmosphere and the planet's capacity to cope with the accelerated rate with which humans burn these fuel sources.
History of the concept
Fire historian Stephen Pyne first used the term in an article, "Fire Age," published by Aeon in 2015, then announced in the more fully developed form in 2019, again in Aeon. In 2019, Pyne used the concept to frame the September fire-focused issue of Natural History magazine and to provide a coda to a revision of Fire: A Brief History. In 2021 he condensed his notions into a small book,The Pyrocene: How We Created a Fire Age, and What Happens Next. The book was translated into Italian, Portuguese, Chinese, and Danish, and reviewed by both Nature and Science.
The Pyrocene has been frequently invoked in news articles about catastrophic wildfires in places like California, Hawaii, and Australia and the growing impact of wildfire smoke. Journalists in outlets including the New York Times, New York Magazine, Wired, and Los Angeles Times. The New Yorker has included it a review of recent books with a fire theme. An overview has appeared in Scientific American.
In his original conception, Pyne imagined the Pyrocene as coextensive with the Holocene (current geological epoch, beginning approximately 11,700 years ago), commencing as a fire-wielding species that interacted more widely with a fire-warming Earth. He introduced the term "pyric transition" to describe the subsequent phase change that occurred when humans began to burn fossil biomass (or what he calls "lithic landscapes") in place of surface biomass ("living landscapes"). Burning in living landscapes has a long evolutionary ecological checks and balances history. Burning fossil biomass lacks those baffles and barriers; the available sources overwhelm the sinks, unhinging air, seas, and terrestrial biotas. Both realms of combustion share an unbroken narrative of humanity's relationship to fire. Pyne has proposed the metaphor of a fire age – the fire-informed equivalent of an ice age to suggest the cumulative magnitude of these effects. The Pyrocene is thus a successor epoch to the Pleistocene.
Interpretations
In the original conception of the term, Pyne advocated for a long Pyrocene that spans the entirety of the Holocene. He acknowledges, however, that the evidence and case for pre-industrial global change through anthropogenic fire is only recently emerging. Most commentators reserve the term for a shorter Pyrocene era that begins with humanity's use of fossil biomass, which changed the use of fire in quantity and kind. Others have modified the concept to refer to that still briefer era of accelerated fossil-fuel burning after World War II. Some consider it a feature best restricted to the 21st century with its eruption of serial conflagrations.
Wildlife ecologist Gavin Jones and others have defined the Pyrocene as "the modern, human-caused era of extreme fire characterized by greater negative impacts to society and ecosystems than in the past." This definition focuses on the more recent impact of human activity on fire regimes, including climate change and fire suppression activities. Jones has argued that fire is a key driver of evolution and situated his research in the framework of the Pyrocene to investigate how species are evolving in response to more frequent and intense wildfires.
Likewise, Australian fire researcher Hamish Clarke has situated the Pyrocene specifically within the recent era of extreme fires exacerbated by changing populations and land use patterns. Others have invoked Pyne's concept of the Pyrocene when discussing recent catastrophic wildfires but have interpreted it as a new era coming after the Holocene, and as an alternative concept to a short Anthropocene.
Interpretations that set the start of this era in the 21st century have suggested that the Earth has just begun to enter the Pyrocene and that the planet can escape an era defined by fire through actions such as the reduction of greenhouse gases in the atmosphere and changes to land use practices, including a selective restoration of a second fire.
References
Geologic time scales
Fire | Pyrocene | [
"Chemistry"
] | 1,502 | [
"Combustion",
"Fire"
] |
63,371,375 | https://en.wikipedia.org/wiki/Selenium%20tetrabromide | Selenium tetrabromide is an inorganic compound with a chemical formula SeBr4.
Preparation
Selenium tetrabromide could be produced by mixing elemental bromine and selenium:
Properties
Selenium tetrabromide exists in two polymorphs, the trigonal, black α-SeBr4 and the monoclinic, orange-reddish β-SeBr4, both of which feature tetrameric cubane-like Se4Br16 units but differ in how they are arranged. It dissolves in carbon disulfide, chloroform and ethyl bromide, but decomposes in water, so that it produces selenous acid in wet air.
The compound is only stable under a bromine-saturated atmosphere; gas phase measurements of the gas density indicate that the compound decomposes into selenium monobromide and bromine.
References
Selenium(IV) compounds
Bromides
Selenium halides | Selenium tetrabromide | [
"Chemistry"
] | 201 | [
"Bromides",
"Salts"
] |
63,373,032 | https://en.wikipedia.org/wiki/Kunioki%20Mima | was a Japanese plasma physicist. He is known for his contributions to the theory of turbulent transport in plasmas, and in particular the derivation of the Hasegawa–Mima equation in 1977, which won him the 2011 Hannes Alfvén Prize.
Life and career
Mima studied physics at Kyoto University and graduated with a bachelor's degree in 1968 and a PhD in 1973. He was a post-doctoral student at Hiroshima University until 1975 and then started work at Osaka University, where he became an assistant professor in 1978 and a professor in 1984. From 1995 to 1999, he was director of the Institute of Laser Engineering. There, his work involved laser fusion (experiments with the Gekko XII laser and FIREX program), free electron lasers, relativistic plasmas and laser-plasma interaction.
Mima died on 5 January 2025, at the age of 79.
Honors and awards
Mima was a Fellow of the American Physical Society and a Member of the Physical Society of Japan and the Japan Society of Plasma Science at Nuclear Fusion Research.
He was a co-recipient of the 1993 John Dawson Award for Excellence in Plasma Physics Research and won the 2007 Edward Teller Award. He was jointly awarded the 2011 Hannes Alfvén Prize (with Akira Hasegawa and Patrick H. Diamond) for "laying the foundations of modern numerical transport simulations and key contributions on self-generated zonal flows and flow shear decorrelation mechanisms which form the basis of modern turbulence in plasmas".
References
1945 births
2025 deaths
Plasma physicists
Japanese plasma physicists
Kyoto University alumni
Fellows of the American Physical Society | Kunioki Mima | [
"Physics"
] | 323 | [
"Plasma physicists",
"Plasma physics"
] |
63,375,308 | https://en.wikipedia.org/wiki/List%20of%20SQL%20reserved%20words | This list includes SQL reserved words – aka SQL reserved keywords, as the SQL:2023 specifies and some RDBMSs have added.
A dash (-) means that the keyword is not reserved.
See also
SQL
SQL syntax
List of relational database management systems
References
SQL
SQL reserved words | List of SQL reserved words | [
"Technology"
] | 60 | [
"Computing-related lists"
] |
63,376,504 | https://en.wikipedia.org/wiki/Introduction%20to%20the%20Theory%20of%20Error-Correcting%20Codes | Introduction to the Theory of Error-Correcting Codes is a textbook on error-correcting codes, by Vera Pless. It was published in 1982 by John Wiley & Sons, with a second edition in 1989 and a third in 1998. The Basic Library List Committee of the Mathematical Association of America has rated the book as essential for inclusion in undergraduate mathematics libraries.
Topics
This book is mainly centered around algebraic and combinatorial techniques for designing and using error-correcting linear block codes. It differs from previous works in this area in its reduction of each result to its mathematical foundations, and its clear exposition of the results follow from these foundations.
The first two of its ten chapters present background and introductory material, including Hamming distance, decoding methods including maximum likelihood and syndromes, sphere packing and the Hamming bound, the Singleton bound, and the Gilbert–Varshamov bound, and the Hamming(7,4) code. They also include brief discussions of additional material not covered in more detail later, including information theory, convolutional codes, and burst error-correcting codes. Chapter 3 presents the BCH code over the field , and Chapter 4 develops the theory of finite fields more generally.
Chapter 5 studies cyclic codes and Chapter 6 studies a special case of cyclic codes, the quadratic residue codes. Chapter 7 returns to BCH codes. After these discussions of specific codes, the next chapter concerns enumerator polynomials, including the MacWilliams identities, Pless's own power moment identities, and the Gleason polynomials.
The final two chapters connect this material to the theory of combinatorial designs and the design of experiments, and include material on the Assmus–Mattson theorem, the Witt design, the binary Golay codes, and the ternary Golay codes.
The second edition adds material on BCH codes, Reed–Solomon error correction, Reed–Muller codes, decoding Golay codes, and "a new, simple combinatorial proof of the MacWilliams identities".
As well as correcting some errors and adding more exercises, the third edition includes new material on connections between greedily constructed lexicographic codes and combinatorial game theory, the Griesmer bound, non-linear codes, and the Gray images of codes.
Audience and reception
This book is written as a textbook for advanced undergraduates; reviewer H. N. calls it "a leisurely introduction to the field which is at the same time mathematically rigorous". It includes over 250 problems, and can be read by mathematically-inclined students with only a background in linear algebra (provided in an appendix) and with no prior knowledge of coding theory.
Reviewer Ian F. Blake complained that the first edition omitted some topics necessary for engineers, including algebraic decoding, Goppa codes, Reed–Solomon error correction, and performance analysis, making this more appropriate for mathematics courses, but he suggests that it could still be used as the basis of an engineering course by replacing the last two chapters with this material, and overall he calls the book "a delightful little monograph". Reviewer John Baylis adds that "for clearly exhibiting coding theory as a showpiece of applied modern algebra I haven't seen any to beat this one".
Related reading
Other books in this area include The Theory of Error-Correcting Codes (1977) by Jessie MacWilliams and Neil Sloane, and A First Course in Coding Theory (1988) by Raymond Hill.
References
External links
Introduction to the Theory of Error-Correcting Codes (2nd ed.) on the Internet Archive
Error detection and correction
Mathematics textbooks
1982 non-fiction books
1989 non-fiction books
1998 non-fiction books | Introduction to the Theory of Error-Correcting Codes | [
"Engineering"
] | 748 | [
"Error detection and correction",
"Reliability engineering"
] |
63,376,505 | https://en.wikipedia.org/wiki/Indo-European%20cosmogony | The Indo-European cosmogony refers to the creation myth of the reconstructed Proto-Indo-European mythology.
The comparative analysis of different Indo-European tales has led scholars to reconstruct an original Proto-Indo-European creation myth involving twin brothers, * ('Man') and * ('Twin'), as the progenitors of the world and mankind, and a hero named * ('Third') who ensured the continuity of the original sacrifice.
Although some thematic parallels can be made with Ancient Near East (the primordial couple Adam and Eve), and even Polynesian or South American legends, the linguistic correspondences found in descendant cognates of *Manu and *Yemo make it very likely that the myth discussed here has a Proto-Indo-European (PIE) origin.
Historiography
Hermann Güntert, stressing philological parallels between the Germanic and Indo-Iranian texts, argued in 1923 for an inherited Indo-European motif of the creation of the world from the sacrifice and dismemberment of a primordial androgyne.
Following a first paper on the cosmogonical legend of Manu and Yemo, published simultaneously with Jaan Puhvel in 1975 (who pointed out the Roman reflex of the story), Bruce Lincoln assembled the initial part of the myth with the legend of the third man Trito in a single ancestral motif.
Since the 1970s, the reconstructed motifs of Manu and Yemo, and to a lesser extent that of Trito, have been generally accepted among scholars.
Myths
Primordial state
The basic Indo-European root for the divine creation is *dheh1, 'to set in place, lay down, or establish', as attested in the Hittite expression nēbis dēgan dāir ("...established heaven (and) earth"), the Young Avestan formula kə huvāpå raocåscā dāt təmåscā? ("What skillful artificer made the regions of light and dark?"), the name of the Vedic creator god Dhātr, and possibly in the Greek name Thetis, presented as a demiurgical goddess in Alcman's poetry. The concept of the Cosmic Egg, symbolizing the primordial state from which the universe arises, is also found in many Indo-European creation myths. A similar depiction of the appearance of the universe before the act of creation is given in the Vedic, Germanic and, at least partly, in the Greek tradition.
Although the idea of a created world is untypical of early Greek thinking, similar descriptions have been highlighted in Aristophanes's The Birds: "...there was Chasm and Night and dark Erebos at first, and broad Tartarus, but earth nor air nor heaven there was..." The analogy between the Greek Χάος ('Chaos, Chasm') and the Norse Ginnungagap ('Gaping abyss') has also been noted by scholars. The importance of heat in Germanic creation myths has also been compared with similar Indian beliefs emphasized in the Vedic hymn on 'cosmic heat'.
Cosmic sacrifice
The first man Manu and his giant twin Yemo are crossing the cosmos, accompanied by a primordial cow. To create the world, Manu sacrifices his brother and, with the help of heavenly deities (the Sky-Father, the Storm-God and the Divine Twins), forges both the natural elements and human beings from his twin's remains.
Manu thus becomes the first priest after initiating sacrifice as the primordial condition for the world order. His deceased brother Yemo turns into the first king as social classes emerge from his anatomy (priesthood from his head, the warrior class from his breast and arms, and the commoners from his sexual organs and legs).
Although the European and Indo-Iranian versions differ on this matter, the primeval cow was most likely sacrificed in the original myth, giving birth to the other animals and vegetables. Yemo may have become the King of the Otherworld, the realm of the dead, as the first mortal to die in the primordial sacrifice, a role suggested by the Indo-Iranian and, to a lesser extent, in the Germanic, Greek and Celtic traditions.
First Warrior
To the third man Trito, the celestial gods offer cattle as a divine gift, which is stolen by a three-headed serpent named * ('serpent'; and the Indo-European root for negation).
Trito first suffers at his hands, but fortified by an intoxicating drink and aided by a helper-god (the Storm-God or *Haner, 'Man'), together they go to a cave or a mountain, and the hero finally manages to overcome the monster. Trito then gives the recovered cattle back to a priest for it to be properly sacrificed. He is now the first warrior, maintaining through his heroic deeds the cycle of mutual giving between gods and mortals.
Interpretations
Three Functions
According to Lincoln, Manu and Yemo seem to be the protagonists of "a myth of the sovereign function, establishing the model for later priests and kings", while the legend of Trito should be seen as "a myth of the warrior function, establishing the model for all later men of arms". He has thus interpreted the narrative as an expression of the priests's and kings's attempt to justify their role as indispensable for the preservation of the cosmos, and therefore as essential for the organization of society. The motif indeed recalls the Dumézilian tripartition of the cosmos between the priest (in both his magical and legal aspects), the warrior (the Third Man), and the herder (the cow).
Primeval hermaphrodite
Some scholars have proposed that the primeval being Yemo was depicted as a two-folded hermaphrodite rather than a twin brother of Manu, both forming indeed a pair of complementary beings entwined together. The Germanic names Ymir and Tuisto were understood as twin, bisexual or hermaphrodite, and some myths give a sister to the Vedic Yama, also called Yamī ('Twin'). The primordial being may therefore have self-sacrificed, or have been divided in two, a male half and a female half, embodying a prototypal separation of the sexes that continued the primordial union of the Sky Father (Dyēus) with the Mother Earth (Dhéǵhōm).
Cattle-raiding myth
The story of Trito served as a model for later cattle raiding epic myths and most likely as a moral justification for the practice of raiding among Indo-European peoples. In their legends, Trito is portrayed as only taking back what rightfully belongs to his people, those who sacrifice properly to the gods. Although cattle raiding is a common theme found in all societies keeping cattle, it was particularly popular among Indo-European peoples, as attested by the legends of Indra and the Panis, Beowulf and Grendel, the quest of Queen Medb for the Bull, or Odysseus hunting down the cattle of Helios.
The myth has been variously interpreted as a cosmic conflict between a heavenly hero and an earthly serpent; as a depiction of the male fellowships' struggle to protect society against external evil; or as an Indo-European victory over non-Indo-European people, the monster symbolizing the aboriginal thief or usurper. The Vedic serpent Vṛtrá is indeed described as a *dāsa, an aboriginal inhabitant who is inimical to the Indo-European invaders; the Iranian serpent Aži Dahāka carries in his name the pejorative suffix -ka; and the Latin inimical giant Cācus is depicted as a non-Indo-European aborigine (incola), hostile to Romans and Greeks alike. According to Martin L. West, the Proto-Indo-European name *Trito ('Third') may have been a "poetic or hieratic code-name, fully comprehensible only with specialized knowledge".
Linguistic evidence
Manu and Yemo
Cognates deriving from the Proto-Indo-European First Priest *Manu ('Man', 'ancestor of humankind') include the Indic Mánu, legendary first man in Hinduism, and Manāvī, his sacrificed wife; the Germanic Mannus (from Germ. *Manwaz), mythical ancestor of the West Germanic tribes; and the Persian Manūščihr (from Av. Manūš.čiθra, 'son of Manuš'), Zoroastrian high priest of the 9th century AD.
From the name of the sacrificed First King *Yemo ('Twin') derive the Indic Yama, god of death and the underworld; the Avestan Yima, king of the golden age and guardian of hell; the Norse Ymir (from Germ. *Yumiyáz), ancestor of the giants (jötnar); and most likely Remus (from Proto-Latin *Yemos), killed in the Roman foundation myth by his twin brother Rōmulus. Latvian jumis ('double fruit'), Latin geminus ('twin') and Middle Irish emuin ('twin') are also linguistically related.
Trito and Ngwhi
Cognates stemming from the First Warrior *Trito ('Third') include the Vedic Trita, the hero who recovered the stolen cattle from the serpent Vṛtrá; the Avestan Thraētona ('son of Thrita'), who won back the abducted women from the serpent Aži Dahāka; and the Norse þriði ('Third'), one of the names of Óðinn. Other cognates may appear in the Greek expressions trítos sōtḗr (τρίτος σωτήρ; 'Third Saviour'), an epithet of Zeus, and tritogḗneia (τριτογήνεια; 'Third born' or 'born of Zeus'), an epithet of Athena; and perhaps in the Slavic mythical hero Troyan, found in Russian and Serbian legends alike.
*Ngwhi, a term meaning 'serpent', is also related to the Indo-European root for negation (*ne-). Descendent cognates can be found in the Iranian Aži, the name of the inimical serpent, and in the Indic áhi ('serpent'), a term used to designate the monstrous serpent Vṛtrá, both descending from Proto-Indo-Iranian *aj'hi.
Comparative mythology
Many Indo-European beliefs explain aspects of human anatomy from the results of the original dismemberment of Yemo: his flesh usually becomes the earth, his hair grass, his bone yields stone, his blood water, his eyes the sun, his mind the moon, his brain the clouds, his breath the wind, and his head the heavens. The traditions of sacrificing an animal before dispersing its parts following socially established patterns, a custom found in Ancient Rome and India, has been interpreted as an attempt to restore the balance of the cosmos ruled by the original sacrifice.
In the Indo-Iranian version of the myth, his brother Manu also sacrifices the cow, and from the parts of the dead animal are born the other living species and vegetables. In the European reflexes, however, the cow (represented by a she-wolf in the Roman myth) serves only as a provider of milk and care for the twins before the creation. This divergence may be explained by the cultural differences between the Indo-Iranian and European branches of the Indo-European family, with the former still strongly influenced by pastoralism, and the latter much more agricultural, perceiving the cow mainly as a source of milk. According to Lincoln, the Indo-Iranian version best preserves the ancestral motif, since they lived closer to the original Proto-Indo-European pastoral way of life.
Indo-Iranian
Creation myth
Mánu ('Man, human') appears in the Rigveda as the first sacrificer and the founder of religious law, the Law of Mánu. He is the brother (or half-brother) of Yama ('Twin'), both presented as the sons of the solar deity Vivasvat. The association of Mánu with the ritual of sacrifice is so strong that those who do not sacrifice are named amanuṣāḥ, which means 'not belonging to Mánu', 'unlike Mánu', or 'inhuman'. The Song of Puruṣa (another word meaning 'man') tells how the body parts of the sacrificed primeval man led to the creation of the cosmos (the heaven from his head, the air from his navel, the earth from his legs) and the Hindu castes (the upper parts becoming the upper castes and the lower parts the commoners). In the later Śatapatha Brāhmana, both a primordial bull and Mánu's wife Manāvī are sacrificed by the Asuras (demi-gods). According to Lincoln, this could represent an independent variant of the original myth, with the figure of Yama laying behind that of Manāvī.After a religious transformation led by Zarathustra around the 7th–6th centuries BC that degraded the status of prior myths and deities, *Manuš was replaced in the Iranian tradition with three different figures: Ahriman, who took his role as first sacrificer; Manūščihr ('son' or 'seed of Manuš'), who replaced him as ancestor of the priestly line; and Zarathustra himself, who took his role as priest par excellence. Manūščihr is described in the Greater Bun-dahišnīh as the ancestor of all Mōpats ('High Priests') of Pars, and it has been proposed that *Manuš was originally regarded as the First Priest instead of Zarathustra by pre-Zoroastrian tribes.
The Indo-Iranian tradition portrays the first mortal man or king, *YamHa, as the son of the solar deity, *Hui-(H)uas-uant. Invoked in funeral hymns of the Rigveda, Yama is depicted as the first man to die, the one who established the path towards death after he freely chose his own departure from life. Although his realm was originally associated with feasting, beauty and happiness, Yama was gradually portrayed as a horrific being and the ruler of the Otherworld in the epic and puranic traditions. Some scholars have equated this abandonment (or transcendence) of his own body with the sacrifice of Puruṣa. In a motif shared with the Iranian tradition, which is touched in the Rigveda and told in later traditions, Yama and his twin sister Yamī are presented as the children of the sun-god Vivasvat. Discussing the advisability of incest in a primordial context, Yamī insists on having sexual intercourse with her brother Yama, who rejects it, thus forgoing his role as the creator of humankind.
In pre-Zoroastrian Iran, Yima was seen as the first king and first mortal. The original myth of creation was indeed condemned by Zarathustra, who makes mention of it in the Avesta when talking about the two spirits that "appeared in the beginning as two twins in a dream ... (and) who first met and instituted life and non-life". Yima in particular is depicted as the first to distribute portions of the cow for consumption, and is explicitly condemned for having introduced the eating of meat. After a brief reign on earth, the king Yima was said in a later tradition to be deprived of his triple royal nimbus, which embodied the three social classes in Iranian myths. Mithra receives the part of the Priest, Thraētona that of the Warrior, and Kərəsāspa that of the Commoner. The saga ends with the real dismemberment of Yima by his own brother, the daiwic figure Spityura. In another myth of the Younger Avesta, the primal man Gayōmart (Gaya marətan; 'Mortal Life') and the primeval world ox Gōšūrvan are sacrificed by the destructive spirit Ahriman (Aŋra Mainyu, 'Evil Spirit'). From the ox's parts came all the plants and animals, and from Gayōmart's body the minerals and humankind. In the Vīdēvdāt, Yima is presented as the builder of an underworld, a sub-terrestrial paradise eventually ruled by Zarathustra and his son. The story, giving a central position to the new religious leader, is once again probably the result of a Zoroastrian reformation of the original myth, and Yima might have been seen as the ruler of the realm of the dead in the early Iranian tradition. Norbert Oettinger argues that the story of Yima and the Vara was originally a flood myth, and the harsh winter was added in due to the dry nature of Eastern Iran, as flood myths didn't have as much of an effect as harsh winters. He has argued that the Videvdad 2.24's mention of melted water flowing is a remnant of the flood myth, and mentions that the Indian Flood Myths originally had their protagonist as Yama, but it was changed to Manu later.
Trita Atpya
Both the Rigveda and the Younger Avesta depict the slaying of a three-headed serpent by a hero named Trita Āptya or Thraēta(ona) Āthwya for the recovery of cattle or women. *Atpya may refer to the name of an Indo-Iranian family of heroes. Both heroes are known as the preparers of the Indo-Iranian sacred beverage, the *sauma, which *Trita Atpya probably drank to obtain god-like powers. The Greek story of Herakles recovering the stolen cattle from the three-headed monster Geryon is likely related, and a Germanic reflex may be found in the depiction of a three-head man fighting three serpents while holding a goat on the Golden Horns of Gallehus.
In the Vedic tradition, Trita Āptya and the god Indra maintain a relationship of mutual assistance, Trita giving soma to the god so that he can, in return, provide help to the hero in his fight against the monster Vṛtrá. The hero confronts the three-headed dragon (áhi-) and kills him to let the cows go out. Finally, Indra cuts off three heads of Vṛtrá and drives the cows home for Trita.
In the Younger Avestan, the stolen cattle was replaced with his two beautiful wives (vantā), said to have been abducted by the serpent Aži Dahāka and whom the hero Thraētona ('son of Thrita') eventually wins back after confronting the monster. Vantā, which means 'female who is desired', has been compared with Indo-Iranian *dhainu ('one who lactates, gives milk'), a frequent word for 'cow' also used to designate female humans. Although Thraētona was aided in his quest by several deities, the pre-Zoroastrian warrior-god *Vr̥traghna ('Smasher of Resistance') appears to be the most probable helper-god in the original Iranian myth, since it was the name borrowed as Vahagn in the Armenian version of the story.
Graeco-Roman
The Roman writer Livy relates the murder of Remus by his brother Rōmulus during the legendary founding of Rome following a disagreement about which hill to build the city on. In a version of the myth, Rōmulus himself is said to have been torn limb-from-limb by a group of senators for being a tyrant, which may represent a reflex of the gods who sacrificed the twin giant in the original motif. Like in the Proto-Indo-European myth, the sacrifice of Remus (Yemos) led to a symbolical creation of humankind, represented by the birth of the three Roman 'tribes' (the Ramnes, Luceres and Tities), and to the enthronement of his brother as the 'First King'.It is likely that Remus was originally seen as the main protagonist of the Latin myth, since the formula initially went by Remo et Romulo, and his name was often used as an elliptical replacement for the whole couple, such as in Remi nepotes ("descendants of Remus"), a poetic name for the Romans. While the name Rōmulus is interpreted as a back-formation of the city name Rōma, Remus is derived from PIE *Yemo, via an intermediary Proto-Latin form *Yemos or *Yemonos. The initial 'y' sound may have shifted to 'r' as a result of long and frequent associations with the names Roma and Rōmulus in Latin myths. In the legend reported by Livy, Rōmulus and Remus were nurtured as infants by a she-wolf, a motif that parallels the cow nourishing Ymir in the Old Norse version.
Some scholars have proposed that the original motifs of Yemo, the Proto-Indo-European sacrificed twin ancestor and ruler of the dead, have been transferred in Greek mythology to three different figures: Kronos, Rhadamanthys and Menealos.
A possible reflex of the original legend of the Third Man *Trito may be found in a Greek myth told by Hesiod. A three-headed monster named Geryon, the grandson of Medusa (the serpent-haired Gorgon), is said to have been killed by Herakles to recover a stolen cattle. The Greek hero is helped by the sun-god Helios, from whom he borrows the cup that helps him cross the western Ocean and reach the island of Erythea. Together with his herdsman Eurytion and his dog, Herakles finally overcomes the monster and drives the cattle back to Greece.
Roman versions of myth, which relied on earlier Greek texts, have been remodelled around an opposition between Hercules and a fire-breathing ogre named Cācus, who lives in a cave on the Aventine. They have nonetheless retained some features of the original three-headed monstrous opponent: Hercules' club, with which he kills Cācus with three strikes, is said to be three-noded; and Hercules runs around the mountain three times after finding the monster's cave, batters the door three times, and sits down to rest three times before finally breaking in. Like in the Iranian and Greek versions, Cācus is portrayed as the one who initially stole the cattle which rightfully belongs to the hero, Hercules.
Germanic
Ymir is depicted in the Eddas as the primal being and a frost jötunn ('giant'). After Óðinn and his brothers killed him, they made the earth out of his flesh, the mountains from his bones, the trees from his hair, the sky from his skull, and the sea and lakes from his blood; and from his two armpits came a man and a woman. The Germanic name Ymir means 'Twin', and some scholars have proposed that it was also understood as hermaphrodite or bisexual. In fact, one of his legs is said to make love to the other one, fathering a six-headed son, the ancestor of the giants. In another Old Norse story, the primeval cow Auðhumla is said to be formed from melting ice like Ymir, and she fed him with her milk.
In his book Germania (ca. 98 AD), Tacitus reports the existence of a myth involving an earth-born god named Tuisto ('Twin') who fathered Mannus ('Man'), the ancestor of West Germanic peoples. Tuisto has begotten Mannus on his own, and his name is also understood to mean hermaphrodite. Some scholars have proposed that the Germanic tribal name Alamanni meant 'Mannus' own people', although 'all-men' remains the most widely accepted etymology among linguists.
A Germanic reflex of myth of Trito fighting the three-headed serpent Ngwhi may be found on the Golden Horns of Gallehus (5th c. AD), where a three-headed man is portrayed as holding a goat and confronting three serpents. One of the names of Óðinn, Þriði ('Third'), is also linguistically related to *Trito. Another reflex may be found in the Norse legend of the giant Hymir who employed an ox head to capture the serpent Jǫrmungandr with the help of the storm-god Thor.
Celtic
A possible Celtic reflex of the Proto-Indo-European myth of creation has been proposed in the Irish epic Táin Bó Cúailnge, where two mythical bulls, Donn Cúalnge ('the Dark [bull] of Cooley') and Findbennach Aí ('the White-horned bull of Aí'), fight each other. The battle ends with the former tearing his opponent limb from limb, creating the Irish landscape out of his body. Donn himself dies shortly after the fight from a broken heart, and thereafter also gives his body to form the island's landscape. Julius Caesar reported that the Gaulish believed in a mythical ancestor he compared to Dīs Pater, the Roman god of the underworld. According to some scholars, this could represent a reflex of the original Proto-Indo-European twin ancestor and ruler of the dead *Yemo, a function similar to that held by the Indo-Iranian Yama.
Parallels and legacy
The motif of Manu and Yemo has been influential throughout Eurasia following the Indo-European migrations. The Greek, Old Russian (Poem on the Dove King) and Jewish versions depend on the Iranian, and a Chinese version of the myth has been introduced from Ancient India. The Armenian version of the myth of the First Warrior Trito depends on the Iranian, and the Roman reflexes were influenced by earlier Greek versions.
Latin tradition
Linguist and comparativist Jaan Puhvel proposed that the characters of "Man" and "Twin" are present in Proto-Latin under the names of Remus (from *Yemo(no)s) and Romulus. The latter was deified as god Quirinus, a name he considered to be ultimately derived from ('man').
Baltic mythology
Baltic mythology records a fertility deity Jumis, whose name means 'pair, double (of fruits)'. His name is also considered a cognate to Indo-Iranian Yama, and related to Sanskrit yamala 'in pairs, twice' and Prakrit yamala 'twins'. Ranko Matasović cites the existence of Jumala as a female counterpart and sister of Jumis in Latvian dainas (folksongs), as another fertility deity, and in the same vein, Zmago Smitek mentioned the pair as having "pronounced vegetational characteristics". Jumis, whose name can also mean 'double ear of wheat', is also considered a Latvian chthonic deity that lived "beneath the plowed field", or a vegetation spirit connected to the harvest.
Following Puhvel's line of argument, Belarusian scholar Siarhiej Sanko attempted to find a Proto-Baltic related pair, possibly named Jumis ("twin") and Viras ("male, hero"). He saw a connection with (quasi-pseudo-)historical Prussian king Widewuto and his brother Bruteno. Related to them is a pair of figures named Wirschaitos and Szwaybrutto (Iszwambrato, Schneybrato, Schnejbrato, Snejbrato) which he interprets as "Elder" and "His Brother", respectively. These latter two would, in turn, be connected to the worship, by the Prussians, of stone statues erected during their expansion in the 12th and 13th centuries.
Indo-Iranian tradition
Later Iranian tradition (Pahlavi) attests a brother-sister pair named Jima (Yima) and Jimak (Yimak). Yimak, or Jamag, is described as Yima's twin sister in the Bundahishn from Central Iran. Yima consorts with his sister Yimak to produce humankind, but is later killed by Azi Dahaka.
The name Yama is attested as a compound in personal names of the historical Persepolis Administrative Archives, such as Yamakka and Yamakšedda (from Old Persian *Yama-xšaita- 'majestic Yama', modern Jamshid).
Nuristani deity Imra is also considered a reflex of Indo-Iranian Yama. The name Imra is thought to derive from *Yama-raja "King Yama", a name possibly cognate to the Bangani title Jim Raza 'god of the dead'. He is also known as Mara "Killer, Death". This name may have left traces in other Nuristani languages: Waigali Yamrai, Kalash (Urtsun) imbro, Ashkun im'ra, Prasun yumr'a and Kati im'ro – all referring to a "creator god". This deity also acts as the guardian to the gates of hell (located in a subterranean realm), preventing the return to the world of the living - a motif that echoes the role of Yama as the king of the underworld.
Footnotes
References
Bibliography
Further reading
Böldl, Klaus. "Von Den Ersten Und Den Letzten Dingen: Kosmogonie, Kosmologie Und Eschatologie Der Edda." In Götter Und Mythen Des Nordens: Ein Handbuch, 93–141. München: Verlag C.H.Beck, 2013. doi:10.2307/j.ctv11693m7.7.
Fraschetti, Augusto, Marian Hill, and Kevin Windle. "The Disappearance of the Founder: Romulus 'cut into Pieces' or His Apotheosis." In: The Foundation of Rome. Edinburgh: Edinburgh University Press, 2005. pp. 85–112. .
Kulikov, Leonid. "The First Woman Yamī, Her Origin and Her Status in Indo-Iranian Mythology: Demigoddess or Half-human? (Evidence from R̥gveda 10.10, Iranian Parallels and Greek Relatives)". In: Studia Ceranea 8, 2018, pp. 43–75. DOI: 10.18778/2084-140X.08.03
Lincoln, Bruce (1981). The Lord of the Dead. History of Religions. 20. pp. 224–41. 10.1086/462869.
Witzel, Michael. (2008). "Slaying the Dragon across Eurasia". In: In Hot Pursuit of Language in Prehistory. pp. 263–286. 10.1075/z.145.21wit.
Yama/Yima: Variations indo-iraniennes sur la geste mythique [Variations on the Indo-Iranian Myth of Yama/Yima]. Edited by Samra Azarnouche and Céline Redard with an introduction by Jean Kellens. College de France: Publications de l'Institut de Civilisation Indienne, fasc. 81. Paris: De Boccard, 2012.
Comparative mythology
Cosmogony
Proto-Indo-European mythology
Religious cosmologies
Religious studies | Indo-European cosmogony | [
"Astronomy"
] | 6,556 | [
"Cosmogony"
] |
72,080,623 | https://en.wikipedia.org/wiki/Leucocoprinus%20bonianus | Leucocoprinus bonianus is a species of mushroom producing fungus in the family Agaricaceae.
Taxonomy
It was first described in 1897 by the French mycologist Narcisse Théophile Patouillard who classified it as Hiatula boniana.
In 2000 it was reclassified as Leucocoprinus bonianus by Zhu Liang Yang.
Description
Leucocoprinus bonianus is a small yellow dapperling mushroom with thin flesh.
Patouillard provided only a brief description of this species:
Cap: Up to 5cm wide, convex and flattening with age with an umbo, it is thin but not fragile. The surface is sulphur yellow and dry with powdery scales. Stem: 7cm tall with a slightly bulbous base. The surface is likewise yellow but less intense than the cap, it is covered in dry powdery scales whilst the interior is hollow. Patouillard noted no stem ring. Gills: Free and presumably yellow (Patouillard only describes the entire 'plant' as being sulphur coloured). Spores: Ovoid with a visible germ pore. 8-10 x 5-6 μm. Patouillard described it as being similar to his previous observation of Leucocoprinus cretaceus but differing in colour and the lack of a ring. However as the ring in many Leucocoprinus species can be fragile and may quickly disappear it is not certain if this specimen had a ring to begin with and simply lost it before being collected.
In 2000 Yang examined the preserved holotype specimen collected by Patouillard which consists of only two pieces of dried cap and added the following to the description:
Cap: 4-5cm wide, brownish (many Leucocoprinus species dry to a brownish colour) with long striations from the cap edges and very thin flesh. The surface is covered with dark grey to blackish woolly scales (floccose squamules) however the color of these is also likely to have darkened and changed as a result of the drying process.
Based on the long striations, the thin flesh and microscopic features it was placed in Leucocoprinus and noted to be very similar to L. birnbaumii. However the distinction from this species is based only on the longer striations and darker coloured scales on the cap and this seems uncertain when the comparison has been made from a dried, partial specimen that is over 100 years old.
Habitat and distribution
The specimens studied by Patouillard were found during August and only described as growing from the ground near the habitations of Ke So in Vietnam. This is about 35 miles south of Hanoi.
Similar species
Leucocoprinus birnbaumii
References
bonianus
Fungi described in 1897
Fungus species | Leucocoprinus bonianus | [
"Biology"
] | 580 | [
"Fungi",
"Fungus species"
] |
72,080,744 | https://en.wikipedia.org/wiki/Secunet%20Security%20Networks | secunet Security Networks AG commonly known as Secunet, is a German information security corporation headquartered in Essen. Secunet develops, manufactures and sells information security hardware and secure telecommunications equipment. It is the producer and vendor of Germany's SINA infrastructure that forms the basis for Germany's secure IT networks. Secunet is Germany's biggest information security company and provides services for the public administration and private enterprises in the country. The company listed publicly in the SDAX.
Secunet was founded in 1997, as a spin-off of the IT division of the former TÜV Mitte AG. Since 2009, Giesecke+Devrient has been the majority shareholder. In 2022, Secunet generated a revenue of 347 million euros and had more than 1,000 employees, thus making it the leading IT security partner of the Federal Republic of Germany. Within Germany Secunet has seats in Berlin, Bonn, Borchen, Dresden, Eschborn, Hamburg, Munich and Siegen.
Products and services
With its products and services, Secunet primarily focuses on clients in the public administration and ministries, the healthcare sector, the defense and space sector as well as specifically security and police agencies.
Secure Networking
One of Secunet's premier products is the SINA (Secure Inter-Network Architecture) product line which was co-developed with Germany's Federal Office for Information Security (BSI). The SINA architecture forms the basis for Germany's classified information networks and is used in a broad range of public institutions in Germany and abroad. The architecture is accredited to the NATO and EU SECRET classifications and includes network encryptors and workstations as well as communication devices, such as encrypted phones.
Border Control
Secunet is the producer of EasyPASS, an automated border control system used at airports and border check points in Germany and a number of EU countries.
Consulting
Secunet's services include information security consulting, assessments and penetration testing.
Healthcare
Germany's electronic healthcare infrastructure is partially based on Secunet products.
External links
secunet Security Solutions
References
Computer companies of Germany
Computer hardware companies
Companies based in North Rhine-Westphalia
Companies based in Essen
Information technology consulting firms of Germany
ICT service providers
Software companies of Germany
Networking hardware companies
Networking software companies
Computer security companies
Companies listed on the Frankfurt Stock Exchange | Secunet Security Networks | [
"Technology"
] | 480 | [
"Computer hardware companies",
"Computers"
] |
72,081,917 | https://en.wikipedia.org/wiki/Goddess%20of%20Victory%3A%20Nikke | Goddess of Victory: Nikke is a third-person shooter action role-playing video game developed by South Korean developer Shift Up and published by Level Infinite. Development of Nikke began as early as 2017, and it was released for Android and iOS in 2022, and Windows in 2023. The game's action-based battle system revolves around quick character-switching and the usage of combat skills in an anime-style environment. The game is free-to-play and features a gacha game system, through which in-app purchases are used as a method for monetization. It garnered over US$70 million in its first month of release.
Goddess of Victory: Nikke is set in a post-apocalyptic future where the surface of the Earth was overthrown by mechanical aliens, called Raptures. The surviving humans fled underground and produced artificial soldiers called Nikkes. The story follows a Commander and his squad of Nikkes who hope to reclaim the surface.
Gameplay
Goddess of Victory: Nikke is a role-playing video game (RPG) in which the player controls one of up to five interchangeable characters (Nikkes) who are distributed in a row facing a battlefield and positioned behind a defensive object. A third-person shooter, the player aims a reticle to shoot at enemies and takes cover to reload—which automatically happens when a character is out of ammunition—allowing them to strategically plan their attacks. Each Nikke wields her own firearm and possess one of five possible elements that determine strengths and weaknesses when attacking foes. Characters each have three unique combat skills: two normal skills and one Burst skill, the latter is each assigned with a numeric value of up to three and requires users to accumulate enough cost, amassable through damaging enemies, before activating the initial Burst—subsequent skills can be activated immediately—and a temporary Full Burst mode is entered upon triggering the final skill, which significantly increases the attack power of all allies.
A stage ends once the player defeats a powerful boss following several swarms of basic enemies. Moreover, a special battle mode called the Interception requires the player to destroy a runaway locomotive throughout the stage. The game features a cooperative multiplayer mode of up to five players who can challenge the environment.
New characters are obtainable via a gacha game system, which costs in-game currency—acquirable by playing the game or via microtransactions—to use. While there is no pity system to guarantee rare characters, players can accumulate mileage tickets every time they draw from the gacha banner, and can exchange a certain amount of mileage tickets for a featured character of their choice at the in-game shop. The player can raise characters' strengths by enhancing their levels and skills, increase their level caps, and equip better armour; the resources for all of those are obtainable by completing various quests.
Story
Goddess of Victory: Nikke takes place in a post-apocalyptic future where the Earth was suddenly attacked by extraterrestrial mechanical creatures called Raptures that destroyed everything on the surface, forcing the remaining humans to take refuge underground and establish the Ark, a metropolis ruled by the Central Government. The PMC manufacturers Elysion, Missilis Industry and Tetra Line—owned by Ingrid, Syuen and Mustang, respectively—that compose the Big Three work on converting women and children into powerful obedient soldiers called Nikkes to be used as weapons to defeat the Raptures and restore humanity on the surface. Due to their prominence, the Big Three CEOs have very high authority; they are, however, heavily monitored by the Central Government to prevent any hostile behavior.
The story is played from the perspective of the Commander who graduated from the Military Academy one day prior to the events of the game; despite this, he performs extraordinarily in the operations and survive various encounters with rare Rapture species throughout the journey. He leads a squad called Counters, which consists of the Nikkes Anis, Rapi and later down the story, Neon. The Commander views Nikkes with sympathy and privately advocates for Nikke rights, which is illegal in accordance with the laws of the Ark. Outlaws may be sent to the Rehabilitation Center or the Outer Rim, an area fully isolated from the rest of the Ark, and they have formed terrorist organizations claiming to fight for human rights for themselves.
Development and release
Nikke was developed by South Korean-based studio Shift Up working with Level Infinite, a publishing brand of Tencent Games. Development began between 2017 and 2018 with an internal planning competition of which one idea was selected to be the predecessor of the game. It was originally planned to be played from a first-person perspective but later was changed to incorporate battle poses inspired by the Gears of War series.
Shift Up's CEO Kim Hyung-tae, who was responsible for the production and illustrations of the game, said in an interview with IGN Japan that the battle environment features life-size models using Live2D, instead of chibi-style characters, to amplify sex appeal. Contributing composers include Hiroyuki Sawano, who produced one of the game's theme song. Shift Up and Level Infinite hosted closed beta tests for the global version between the announcement and its release, allowing selected registrants to test out the game mechanics. The game contains voice-overs in English, Japanese and Korean.
Shift Up first revealed Nikke along with Stellar Blade at the Crank in Showcase event in 2019, with several trade exhibitions being held ahead of its launch, such as at BEXCO and Tokyo Game Show. The game was initially planned to be released worldwide for Android and iOS in 2020, but it was rescheduled and officially released on November 4, 2022. A Microsoft Windows version of the game was released on February 15, 2023, with, soon later, a brand collaboration with manga series Chainsaw Man that introduced characters therefrom as playable characters. The game has since collaborated with the RPG Nier: Automata in September of the same year and the series Re:Zero in March 2024.
Reception
Pete Davison of Rice Digital criticized the early gameplay for being too easy to the point that "it feels at odds with the narrative at times". He called the character design a "thirst trap" and "horny to an almost satirical degree". He describes the story atmosphere as having "an interesting, almost Nier-esque melancholy". He remarks the early killing of Marian, calling it "a ballsy move" because it "means deliberately eschewing potential income".
According to data analysis from SensorTower, Nikke grossed over $70 million in revenue in its first month of release, which was mostly generated from Japan, South Korea, and the United States. It reached a total of $400 million less than one year after its release, and saw over 25 million downloads before the Windows port's release. PocketGamer.biz reported that though the game's "excess of fanservice" played a significant role in its "more than respectable levels of success", its unique gacha mechanics may have also been a contributing factor.
Goddess of Victory: Nikke was nominated for the Famitsu Dengeki Game Awards 2022's "Best App" category.
Controversies
Following the release of a character costume, players criticized Tencent for having the design altered from beta versions to show less revealing clothing. Since Tencent is based in China, its video games must adhere to the censorship policies of China in addition to those of other jurisdictions.
In January 2023, an official Thai advertisement—which depicted a Nikke player watching Anis', Rapi's and Marian's bouncing buttocks and fantasizing about such with cosplayers—was taken down and apologized for by Tencent after they received backlash from Thai fans who were unhappy with the portrayal of the playerbase. This pullback, however, faced another backlash from a different portion of fans who were already upset with the censorship, claiming that "there is nothing wrong with the ad for being honest about why some players are attracted to the game".
Notes
References
Sources
External links
2022 video games
Action role-playing video games
Android (operating system) games
Cooperative video games
Free-to-play video games
Gacha games
iOS games
Multiplayer and single-player video games
Post-apocalyptic video games
Science fiction role-playing video games
Shift Up games
Tencent
Third-person shooters
Video game controversies
Video games developed in South Korea
Video games featuring female protagonists
Video games featuring non-playable protagonists
Windows games
World War III video games
Nike (mythology)
Level Infinite games
Transhumanism in fiction
Video games about cyborgs
Fiction about nanotechnology | Goddess of Victory: Nikke | [
"Materials_science"
] | 1,764 | [
"Fiction about nanotechnology",
"Nanotechnology"
] |
72,082,890 | https://en.wikipedia.org/wiki/TOI-1136 | TOI-1136 is a G-type main-sequence star away in the constellation Draco. It is slightly smaller than the Sun and similar in mass and temperature, but is much younger, with an age of about 700 million years. It hosts a system of at least six, and possibly seven, exoplanets.
Planetary system
TOI-1136 was discovered to have six transiting planets in 2022 using the Transiting Exoplanet Survey Satellite (TESS), all orbiting closer to their star than Mercury is to the Sun. All of them are Neptune-sized or mini-Neptunes, and their masses have been measured using a combination of radial velocity and transit-timing variations, showing them to have low densities. The planets are in an orbital resonance, with period ratios near 3:2, 2:1, 3:2, 7:5, and 3:2.
A possible single transit of a seventh planet was also identified. This candidate planet would also be sub-Neptune-sized, but its orbit is poorly constrained. If this is confirmed, it would make TOI-1136 one of the largest known planetary systems.
See also
HD 110067
Kepler-90
Kepler-385
TOI-178
TRAPPIST-1
References
Draco (constellation)
G-type main-sequence stars
Planetary systems with six confirmed planets
J12484436+6451191
BD+65 0902
1136
142276270 | TOI-1136 | [
"Astronomy"
] | 302 | [
"Constellations",
"Draco (constellation)"
] |
72,083,500 | https://en.wikipedia.org/wiki/Time%20in%20Panama | Panama observes Eastern Standard Zone (UTC−5) year-round.
IANA time zone database
In the IANA time zone database, Panama is given one zone in the file zone.tab—America/Panama. "PA" refers to the country's ISO 3166-1 alpha-2 country code. Data for Panama directly from zone.tab of the IANA time zone database; columns marked with * are the columns from zone.tab itself:
References
External links
Current time in Panama at Time.is
Time in Panama at TimeAndDate
Time by country
Geography of Panama | Time in Panama | [
"Physics"
] | 118 | [
"Spacetime",
"Physical quantities",
"Time",
"Time by country"
] |
72,084,320 | https://en.wikipedia.org/wiki/Georgia%20Purdom | Georgia Purdom (née Hickman; born 1972) is an American biologist and Young Earth creationist. She is the director of Educational Content at Answers in Genesis.
Early life
Purdom was born in 1972, and grew up near Columbus, Ohio in what she described as a "very strong Christian home". She attended a Nazarene church.
Education and career
Purdom studied at Cedarville University, graduating in 1994, before going on to get a PhD in molecular genetics from Ohio State University. She was an associate professor of biology at Mount Vernon Nazarene University before joining Answers in Genesis. She received the Alumna of the Year award from Cedarville in 2015.
Views
Purdom believes that whether one holds a "biblical versus secular" worldview determines how one interprets scientific data. She also believes that "available evidence supports and confirms biblical creation."
She is the editor of Galapagos Islands: A Different View (2013) which presents a "Bible-based analysis of the islands." Purdom claims that the Galápagos Islands were formed after the Genesis Flood.
Purdom distinguishes her creationist views with that of intelligent design, which she does not regard as Christian.
Purdom claimed that "mutations don’t cause the gain of novel traits—the gain of genetic information—necessary to change from one kind of organism into another" without providing any evidence for that claim. In fact, there are numerous studies demonstrating exactly such changes, especially supported by phylogenetic studies and genome analyses. For instance, novel morphological features are easily selected for in dog breeding and their genetic basis has been well documented. Many other examples are documented in studies on macro-evolution.
Scientific work
Purdom has published three studies that are indexed in Pubmed, all of which apparently resulted from her thesis work at Ohio State University. All three investigate the role of microphthalmia transcription factor (MITF), a protein that regulates gene expression during osteoclast differentiation. None of this work is directly related to evolutionary biology, although the studies show that they are fully compatible with the evolution of gene regulatory networks.
References
External links
Blog at Answers in Genesis
1972 births
Living people
American Christian Young Earth creationists
Creation scientists
American women geneticists
American geneticists
Cedarville University alumni
Ohio State University alumni
Mount Vernon Nazarene University faculty
Molecular geneticists
American members of the Church of the Nazarene
Scientists from Ohio | Georgia Purdom | [
"Biology"
] | 492 | [
"Molecular geneticists",
"Molecular genetics"
] |
72,084,406 | https://en.wikipedia.org/wiki/Tyrosinol | Tyrosinol is an organic compound with the formula . A colorless or white solid, it is produced by the reduction of the amino acid tyrosine with borane dimethylsulfide. The compound, which is chiral, is an example of a 1,2-ethanolamine as well as a phenethylamine.
Related compounds
Tyrosol,
References
Primary alcohols
Amines | Tyrosinol | [
"Chemistry"
] | 84 | [
"Amines",
"Bases (chemistry)",
"Functional groups"
] |
72,085,266 | https://en.wikipedia.org/wiki/Control%20coefficient%20%28biochemistry%29 | In biochemistry, control coefficients are used to describe how much influence a given reaction step has on the flux or concentration of the species at steady state. This can be accomplished experimentally by changing the expression level of a given enzyme and measuring the resulting changes in flux and metabolite levels. In theory, any observables, such as growth rate, or even combinations of observables, can be defined using a control coefficient; but flux and concentration control coefficients are by far the most commonly used.
The simplest way to look at control coefficients is as the scaled derivatives of the steady-state change in an observable with respect to a change in enzyme activity ( for each species ). For example, the flux control coefficients (, where is the reaction rate) can be written as:
while the concentration control coefficients (, where is the concentration of species ) can be written as:
The approximation in terms of percentages makes control coefficients easier to measure and more intuitively understandable.
Control coefficients can have both negative and positive values. A negative value indicates that the observable in question decreases as a result of the change in enzyme activity.
It is important to note that control coefficients are not fixed values but will change depending on the state of the pathway or organism. If an organism shifts to a new nutritional source, then the control coefficients in the pathway will change. As such, control coefficients form a central component of metabolic control analysis.
Formal Definition
One criticism of the concept of the control coefficient as defined above is that it is dependent on being described relative to a change in enzyme activity. Instead, the Berlin school defined control coefficients in terms of changes to local rates brought about by any suitable parameter, which could include changes to enzyme levels or the action of drugs. Hence a more general definition is given by the following expressions:
and concentration control coefficients by
In the above expression, could be any convenient parameter. For example, a drug, changes in enzyme expression etc. The advantage is that the control coefficient becomes independent of the applied perturbation. For control coefficients defined in terms of changes in enzyme expression, it is often assumed that the effect on the local rate by changes to the enzyme activity is proportional so that:
Relationship to rate-limiting steps
In normal usage, the rate-limiting step or rate-determining step is defined as the slowest step of a chemical reaction that determines the speed (rate) at which the overall reaction proceeds. The flux control coefficients do not measure this kind of rate-limitingness. For example, in a linear chain of reactions at steady-state, all steps carry the same flux. That is, there is no slow or fast step with respect to the rate or speed of a reaction. The flux control coefficient, instead, measures how much influence a given step has on the steady-state flux. A step with a high flux control coefficient means that changing the activity of the step (by changing the expression level of the enzyme) will have a large effect on the steady-state flux through the pathway and vice versa.
Historically the concept of the rate-limiting steps was also related to the notion of the master step. However, this drew much criticism due to a misunderstanding of the concept of the steady-state.
See also
Elasticity coefficient
Metabolic control analysis
Summation theorems (biochemistry)
References
Biochemistry methods
Metabolism
Mathematical and theoretical biology
Systems biology | Control coefficient (biochemistry) | [
"Chemistry",
"Mathematics",
"Biology"
] | 679 | [
"Biochemistry methods",
"Mathematical and theoretical biology",
"Applied mathematics",
"Cellular processes",
"Biochemistry",
"Metabolism",
"Systems biology"
] |
72,087,465 | https://en.wikipedia.org/wiki/Te%20lapa | Te lapa is a Polynesian term for an unexplained light phenomenon underneath, or on the surface of, the ocean. Te lapa has been loosely translated as "flashing light", "underwater lightning", "the flashing", or "something that flashes". It was used by historic and modern Polynesians as a navigation aid to find islands in the Pacific Ocean. In some instances, it has been theorized to be bioluminescence or electromagnetic in nature. Other hypotheses include the interference patterns of intersecting waves creating a raised curve acting as a lens, but would not explain the source of light. David Lewis speculated that te lapa may originate from luminescence of organisms, or related to deep swell, ground swell, or backwash waves from reefs or islands.
History
Te lapa was brought to the attention of academia by David Lewis with the publication of his book We, the Navigators in 1972. The book dispelled the former academic belief that Polynesians colonized the islands haphazardly by drifting and without navigational aids. Lewis documented many non-instrumental methods used for navigation, most explainable by science except for te lapa. Later on in 1993, Marianne George would voyage with Lewis and together worked with Kaveia, a native of Taumako, to define the origin and nature of te lapa.
Eventually George would witness te lapa on several occasions with help from Kaveia. She described it as a natural phenomenon and used for piloting, best seen at night. The light is followed toward its origin from islands, or to reorient boat pilots at sea. Kaveia noted that te lapa is used for navigation no more than 120 miles from shore, and rarely as close as 2 miles from shore due to the island already being visible from that distance. It is typically white in color, though its color may be dependent upon the makeup of the water. It was also described as having the shape of a straight line. Lewis, who had also seen the lights, described it as "streaking", "flickering", "flashes", "darts", "bolts", or "glowing plaques" but never as jagged, like lightning. Lewis noted that te lapa would travel slower farther out at sea, and faster when closer to shore, often having a "rapid to-and-fro jerking character." Lewis was instructed by Bongi, a native of Matema atoll, that te lapa was best seen 80 to 100 miles from shore.
Other Polynesian cultures are likely to have different names for the same phenomenon. On the island of Nikunau it is referred to as "te mata" and "ulo aetahi" (Glory of the Seas). On Tonga, "ulo aetahi" may be "ulo a'e tahi" and have other names such as "te tapa" translated as "to burst forth with light." Lewis noted that Tikopians were unaware of te lapa.
George, having been to sea many times, had seen many "ocean lights" from known sources, ruled out what te lapa was not. Ruled-out phenomena include: ball lightning, tektites, bioluminescence, luminescence, St. Elmo's fire, shooting stars/meteors, satellites, comets, unique colors visible at sunset or when the sun is occluded, celestial bodies, military firing ranges, fishing and military buoys, ice mirages, light mirroring, rainbows, glories, crepuscular rays, sun dogs, moon dogs, iceblink, looming from clouds, aurorae, asterisms, earthquake lights, and a large range of light shadowing, fractured lights, color, and mirage arcs from light phenomenon above 60° latitude. George also mentioned that Kaveia interpreted other known and explained phenomena, as well as other unexplained phenomena such as "Te Akua" also known as "the devil lights".
Skepticism
Richard Feinberg, a Kent State University professor, has, however, claimed that the phenomenon has not been scientifically written about, that there are few references to it, and that there are disagreements among sailors about how the phenomenon operates. Still, Feinberg interviewed sailors who believed in te lapa and said that they used it to navigate. He concluded his publication on te lapa with the remark "[a]lthough I am not quite ready dismiss te lapa out of hand, it is hard to see how a phenomenon so rare and difficult to find could be a dependable navigational tool, particularly in an emergency situation—precisely when it would be needed."
References
Further reading
Light
Unexplained phenomena
Polynesian navigation
Polynesian words and phrases | Te lapa | [
"Physics"
] | 986 | [
"Physical phenomena",
"Spectrum (physical sciences)",
"Electromagnetic spectrum",
"Waves",
"Light"
] |
72,089,297 | https://en.wikipedia.org/wiki/Caroline%20Thomas%20Rumbold | Caroline Thomas Rumbold (July 22, 1877 – November 7, 1949) was an American botanist. She specialized in forest pathology. Her researches focused on “fungus diseases of trees and blue stain fungi of wood.”
Biography
Born on July 22, 1877, in St. Louis, Missouri, United States, Caroline Thomas Rumbold was the daughter of Thomas Frasier Rumbold and Charlotte E. Ledengerber.
In 1901 she graduated from Smith College in Massachusetts. She got both the master's degree and the doctorate from the Washington University in St. Louis.
She started her career as an assistant at the Bureau of Plant Industry, United States Department of Agriculture in 1903. She later moved to University of Missouri to become an assistant in botany. From 1929 to 1942 she had a long career as an associate pathologist at the Department of Plant Pathology in the University of Wisconsin–Madison. She briefly worked as a fellow at the Missouri Botanical Garden.
She was associated with a number of professional institutions including Phytopathological Society, the American Society of Plant Physiologists and the Botanical Society of Washington.
She died on November 7, 1949, in Cleveland, Ohio, United States.
References
1877 births
1949 deaths
Pathology
American physiologists
Plant physiologists
American women botanists
American women physiologists
American women academics
20th-century American botanists
20th-century American women scientists
Smith College alumni
Washington University in St. Louis alumni
University of Wisconsin–Madison staff | Caroline Thomas Rumbold | [
"Biology"
] | 301 | [
"Pathology"
] |
72,089,950 | https://en.wikipedia.org/wiki/ER%20Ursae%20Majoris | ER Ursae Majoris is a variable star in the northern circumpolar constellation of Ursa Major, abbreviated ER UMa. It is a prototype system for a subclass of SU Ursae Majoris dwarf novae. The system ranges in brightness from a peak apparent visual magnitude of 12.4 down to 15.2, which is too faint to be visible to the naked eye. The distance to this system, based on parallax measurements, is approximately 1,163 light years.
This system was identified as an ultraviolet excess object as part of the Palomar-Green (PG) survey by R. F. Green and associate in 1986. It was given the catalog identifier PG 0943+521, and was confirmed to be cataclysmic variable. In 1992, it was determined this is a dwarf nova that ranges in brightness from magnitude 12.3 down to 15.2. F. A. Ringwald in 1993 found a candidate orbital period of 0.1997 days based on radial velocity variation, but with some uncertainty.
In 1995, T. Kato and C. Kunjaya confirmed this is a SU Ursae Majoris-type dwarf nova, and noted the unusual nature of this system, finding it has a long superoutburst lasting about 20 days and the supercycle (the time between superoutbursts) is very short at around 43 days. Large amplitude superhumps were found to occur near the start of a superoutburst, with a brightness increase of around 0.35 magnitude. The properties of the system suggest a high mass transfer rate and the white dwarf component is hotter than in other typical dwarf novae. During periods of quiescence, the accretion rate is ·yr−1.
References
Further reading
M-type main-sequence stars
White dwarfs
Cataclysmic variable stars
Ursa Major
Ursae Majoris, ER | ER Ursae Majoris | [
"Astronomy"
] | 390 | [
"Ursa Major",
"Constellations"
] |
72,090,512 | https://en.wikipedia.org/wiki/Karen%20Hudson-Edwards | Karen A. Hudson-Edwards is a Canadian mineralogist and geochemist. She is a professor at the University of Exeter, where she specializes in sustainable mining jointly between the Camborne School of Mines and the Environment and Sustainability Institute (University of Exeter). Specifically, she has delved into research on contaminant cycling, remediation strategies for mining waste, surface and ground water, sustainable mining practices, and the circular economy in mining.
Education
Born in Canada, Hudson-Edwards studied Geology at Queen's University at Kingston in 1981. She graduated in 1985, attaining her BSc in the Department of Geological Sciences. Edwards then went onto receive her MSc in Earth Science at Memorial University of Newfoundland from 1985 to 1988. From 1993 until 1996, Karen Hudson-Edwards achieved her PhD from the University of Manchester in the study of Environmental Mineralogy and Geochemistry.
Before her receiving her PhD, Edwards worked as geologist for the Geological Survey of Canada until 1989, before operating as an Exploration Geologist for Falconbridge Ltd. from the same year up to 1992.
Post-PhD, Hudson-Edwards assisted temporarily as a Postdoctoral Research Fellow for the School of Geography, at the University of Leeds.
Career
She has worked in the Department of Earth and Planetary Sciences at Birkbeck University of London for almost 20 years, before joining the Environment and Sustainability Institute and Camborne School of Mines in October 2017. Her research focuses on the environmental impact of mine wastes, including understanding their character, stability, impact, remediation, and reuse. In her research she looked into specific examples such as Fundão and Santarém mine tailings dam failure in Minas Gerais, Brazil, on November 5, 2015, and how it showed the world the results of unsustainable mining.
She also has conducted detailed mineralogical and geochemical studies on the effects of mining on river sediments, particularly in the Rio Tinto and Rio Pilcomayo regions between 1999-2001.
In 2019 she was invited to be the European Association of Geochemistry Distinguished Lecturer for 2019. Hudson-Edwards has authored more than 120 scientific articles and has an h-index of 49.
She was recognized by the '100 Global Inspirational Women in Mining' publication in 2022 as one of the most inspirational women in mining worldwide.
In addition to her research, she advises the Eden Project with their Living Worlds Exhibit which was on display until 2023. Furthermore, Hudson-Edwards is advising the law commission on their consultation on Regulating Coal Tip Safety in Wales. She is a member of the editorial board of the peer-reviewed publication called the Journal of Geochemical Exploration and Mineralogical Magazine, and associate editor for Frontiers in Earth Sciences, and Geoscience and Society. In addition, she currently holds the position of publications manager for the Mineralogical Society of Great Britain and Ireland.
Recently she has been contributing, and working with fellow researchers in natural carbon mineralization. Specifically, delving into the influence on the Geochemical Evolution of Coal-Based Aquifers in the Salt Ranges, in Punjab and Pakistan.
Research and contributions
References
Year of birth missing (living people)
Living people
Canadian women geologists
Canadian women chemists
Canadian expatriate academics in the United Kingdom
Canadian mineralogists
Women mineralogists
Canadian geochemists
Queen's University at Kingston alumni
Academics of the University of Exeter
Academics of Birkbeck, University of London
Memorial University of Newfoundland alumni
Women geochemists
Alumni of the University of Manchester
Canadian expatriates in England | Karen Hudson-Edwards | [
"Chemistry"
] | 704 | [
"Geochemists",
"Canadian geochemists",
"Women geochemists"
] |
72,091,336 | https://en.wikipedia.org/wiki/Sun%20Radio%20Interferometer%20Space%20Experiment | The Sun Radio Interferometer Space Experiment (SunRISE), is a set of CubeSats designed to study solar activity by acting as an aperture synthesis radio telescope. It is intended to monitor giant solar particle storms.
The satellites will occupy a supersynchronous geosynchronous Earth orbit.
The participants in the experiment include JPL, the University of Colorado Boulder and the University of Michigan. It is due to be launched in 2024.
Status
, the six satellites have been built and are going into storage to await their Vulcan Centaur launch vehicle.
References
Satellite constellations
Radio telescopes
Space telescopes
Interferometric telescopes
2024 in spaceflight | Sun Radio Interferometer Space Experiment | [
"Astronomy"
] | 132 | [
"Space telescopes",
"Astronomy stubs",
"Spacecraft stubs"
] |
72,093,304 | https://en.wikipedia.org/wiki/Trustworthy%20AI | Trustworthy AI refers to artificial intelligence systems designed and deployed to be transparent, robust and respectful of data privacy.
Trustworthy AI makes use of a number of Privacy-enhancing technologies (PETs), including homomorphic encryption, federated learning, secure multi-party computation, differential privacy, zero-knowledge proof.
The concept of trustworthy AI also encompasses the need for AI systems to be explainable, accountable, and robust. Transparency in AI involves making the processes and decisions of AI systems understandable to users and stakeholders. Accountability ensures that there are protocols for addressing adverse outcomes or biases that may arise, with designated responsibilities for oversight and remediation. Robustness and security aim to ensure that AI systems perform reliably under various conditions and are safeguarded against malicious attacks.
ITU standardization
Trustworthy AI is also a work programme of the International Telecommunication Union, an agency of the United Nations, initiated under its AI for Good programme. Its origin lies with the ITU-WHO Focus Group on Artificial Intelligence for Health, where strong need for privacy at the same time as the need for analytics, created a demand for a standard in these technologies.
When AI for Good moved online in 2020, the TrustworthyAI seminar series was initiated to start discussions on such work, which eventually led to the standardization activities.
Multi-Party Computation
Secure multi-party computation (MPC) is being standardized under "Question 5" (the incubator) of ITU-T Study Group 17.
Homomorphic Encryption
Homomorphic encryption allows for computing on encrypted data, where the outcomes or result is still encrypted and unknown to those performing the computation, but can be deciphered by the original encryptor. It is often developed with the goal of enabling use in jurisdictions different from the data creation (under e.g. GDPR).
ITU has been collaborating since the early stage of the HomomorphicEncryption.org standardization meetings, which has developed a standard on homomorphic encryption. The 5th homomorphic encryption meeting was hosted at ITU HQ in Geneva.
Federated Learning
Zero-sum masks as used by federated learning for privacy preservation are used extensively in the multimedia standards of ITU-T Study Group 16 (VCEG) such as JPEG, MP3, and H.264, H.265 (aka MPEG).
Zero-knowledge proof
Previous pre-standardization work on the topic of zero-knowledge proof has been conducted in the ITU-T Focus Group on Digital Ledger Technologies.
Differential privacy
The application of differential privacy in the preservation of privacy was examined at several of the "Day 0" machine learning workshops at AI for Good Global Summits.
See also
Artificial Intelligence
Privacy-enhancing technologies
Data Science
References
2020 establishments
Information privacy
United Nations Economic and Social Council
International Telecommunication Union
Artificial intelligence associations
Regulation of artificial intelligence | Trustworthy AI | [
"Technology",
"Engineering"
] | 576 | [
"Cybersecurity engineering",
"Computing and society",
"Information privacy",
"Regulation of artificial intelligence"
] |
72,094,215 | https://en.wikipedia.org/wiki/Meadow%20knapweed | Meadow knapweed (Centaurea × gerstlaueri), also known as hybrid knapweed or protean knapweed, is a fertile hybrid between black knapweed (Centaurea nigra) and brown knapweed (Centaurea jacea). The taxonomic status of the species is uncertain, and meadow knapweed has been variously described as different species.
Description
Meadow knapweed is a perennial forb that grows to 20–40 inches tall. The branched stems rise above a woody root crown. The seedlings have a tap root, but the mature plants develop a cluster of roots below the root crown. Meadow knapweed reproduces mostly by seed, but its root fragments can resprout after disturbance. The seeds naturally disperse only a few meters, but they can disperse further via animals, humans, vehicles, or water.
The leaves become progressively smaller up the stem. The lower leaves can have either smooth, coarsely lobed, or toothed edges, and can grow to 6 inches long and 1.5 inches wide. The upper leaves tend to have smooth edges and are almost like bracts.
Flowers are pink to reddish-purple, or occasionally white, the flowers are larger and showier than the flowers of other knapweeds. The flowerheads are about the size of a nickel and are more rounded than the flowerheads of other knapweeds. A single flowerhead tips the end of each branch. Underneath the flowerhead are distinctive light to dark-brown bracts with papery, fringed margins. Black knapweed has dark, comb-like bracts, while brown knapweed has rounded, papery tips. Meadow knapweed is intermediate between the two.
The fruit is an achene (a dry fruit with a single seed and thin walls that does not open at maturity; for example, a sunflower "seed"). The achenes are 1/8 inch long, and they are ivory-white to light brown. Seeds may retain viability for up to five years in the soil.
A hybrid itself, meadow knapweed hybridizes with yellow starthistle (Centaurea solstitialis) and diffuse knapweed (Centaurea diffusa).
Habitat and ecology
Black knapweed was probably introduced to North America from ship ballast or as an ornamental. Brown knapweed was purposefully introduced to North America as a forage crop. Meadow knapweed arose as a hybrid of these two species. It is not very palatable to animals; therefore it easily outcompetes other forage species. Meadow knapweed prefers moist sites in full sunshine, infesting river banks, pipelines, roadsides, fields, and pastures. Once established, infestations of meadow knapweed are difficult to remove. Despite its invasive status, gardeners plant it as an ornamental or as a pollen source for honeybees.
Meadow knapweed is considered an invasive species and noxious weed in some areas. Meadow knapweed has the ability to out-compete grasses and other species used for livestock forage, and may take over native prairie and savannah ecosystems. It is common in ruderal areas such as roadsides, clear cuts, and industrial areas. It is a threat to native species such as Plagiobothrys hirtus.
The species is found widely on continental North America, as well as in South Africa and Australia.
Management
Meadow knapweed is considered a noxious weed in British Columbia, Idaho, Oregon, and Washington. Cultivating areas is shown to reduce populations of meadow knapweed. Hand removal can be effective, but herbicide use is recommended.
The weevil Larinus obtusus is used as a biological control. Larva of the weevil feed on seeds and adults damage the leaves. The flies Urophora affinis and U. quadrifasciata were introduced in the 1960s to combat knapweeds. The moth Metzneria paucipunctella has also been introduced as a control method. However, biological control alone is not a totally effective way of eradicating meadow knapweed.
Taxonomy
The taxonomic status of this species is uncertain. It has been variously published as Centaurea × gerstlaueri, Centaurea debeauxii ssp. thuillieri, Centaurea jacea var. pratensis, Centaurea jacea subsp. × pratensis, Centaurea nigra var. radiata, and Centaurea thuillieri. The Invasive Species Compendium refers to meadow knapweed as Centaurea debeauxii.
References
Hybrid plants
Centaurea | Meadow knapweed | [
"Biology"
] | 963 | [
"Hybrid plants",
"Plants",
"Hybrid organisms"
] |
72,095,183 | https://en.wikipedia.org/wiki/Flag%20families | Flag families are sets of national and other flags with similarities in their design, often based on a shared history, culture, or influence. Families do not include flags with coincidental similarities. Flags may be in multiple flag families. Only twelve current national flags existed before the 19th century, when large-scale flag use began. Seven of these flags (Denmark, France, the Netherlands, Russia, Turkey, the United Kingdom, and the United States) are the inspiration for more than 130 current national flags and ensigns.
Christian cross
A Christian cross flag is any flag with a cross or crosses as a central element of its design (as opposed to flags like those of Malta and Serbia, which use crosses as smaller embellishments). It is the oldest flag family. The first flag purported to have such a cross was the flag of Portugal, beginning in around 1100. The flag design became the most common design for merchant ships across Europe for several centuries. Flags in this family use different types of crosses, including the Latin cross (†), the Greek cross (✚), and the Maltese cross (✠). (The Maltese cross does not appear on Malta's national flag, only its civil ensign.)
Nordic cross
Flags in the Nordic cross family feature crosses stretching the width and length of the flag, with the center offset to hoist. The cross design represents Christianity; Denmark was the first to adopt this design in the 14th century. As the oldest national flag in continuous use, the flag of Denmark served as inspiration for other Nordic countries as they adopted theirs. Though the design is strongly associated with Nordic countries, cities and territories outside the region use this design. Greenland is the only Nordic region that does not use the Nordic cross.
Crescent
Flags with crescents are recorded as being used in the region of Middle East and North Africa as early as the 14th century. These designs often featured a white crescent open toward the top on a solid-colored field. During the 19th century when national flags became common, the Ottoman Empire was the only Muslim state considered a world power. Its flag popularized the crescent design for other Muslim nations when they later adopted flags. Most Muslim crescent flags also have one or more stars near or within the circle formed by the crescent. The crescent appears on several flags of non-Muslim subnations and municipals. These crescent flags have symbolism unrelated to Islam.
British Ensign
The British Ensign family is composed of flags with the Union Jack in the canton. The Union Flag adopted in 1606 combined the Saint George's Cross of England and the St. Andrew's saltire of Scotland to form the Union Flag. The Saint Patrick's saltire was added to the flag in 1801. In the mid-19th century, the British government declared the use of a white ensign for use by the Royal Navy, a red ensign for non-government vessels, and a blue ensign for all vessels "belonging to, or permanently in, the service of the Colonies." As the British Empire expanded, so too did the use of variations of the ensigns, especially the blue ensign. Of the original fifty-three independent nations in the British Commonwealth, all but four had the Union Jack on their flag. Forty-four have removed the Union Jack from their flags.
Stars and Stripes
The stars and stripes flag family is composed of flags of alternating stripes with a field in the hoist (often the canton) charged with an emblem (often, but not always, a star or stars). Early versions of the flag of the United States were based on ensigns of the United Kingdom, with the Union Flag on the canton. Instead of a solid-colored field, they had stripes inspired by the flag of the East India Company. In 1777, the Continental Congress of the United States resolved to replace the Union Flag with thirteen stars. The first nation to adopt a similar flag was the Hawaiian Kingdom, and many other nations wanting to express ideals of liberty and democracy followed suit.
Dutch and pan-Slavic colors
Dutch and pan-Slavic colors are a family of flags, usually with red, white, and blue stripes, inspired by the Dutch and later Russian flags. The first flag of simple stripes were the livery colors of William I, Prince of Orange, used in the mid-16th century. These stripes of orange, white, and blue became the first flag of the Netherlands. In the 17th century, the orange was replaced by red. Tsar Peter the Great personally designed a merchant flag of Russia based on the colors of the flag of the Netherlands. The Russian flag, in turn, inspired many flags of countries in the Slavic region. Most retained the white, blue and red, but Bulgaria changed the blue stripe on the flag of Russia into a light green stripe.
Tricolours and tribands
A tricolor is any flag following the flag of France in its design of three vertical stripes of equal width, each distinct in color. On the eve of the French Revolution, 13 July 1789, red and blue cockades were given to the militia of Paris. Soon afterward, Louis XVI added one to his royal white cockade. These colors, arranged as stripes, became the flag of France in 1794. In this way, vertical tribands of three colors became associated with movements for republicanism and were adopted by many nations transitioning to republican governance, although their use was never exclusive to such states. Unlike tricolour, the triband design may contain two identical colors, such as flags of Nigeria and Peru.
A number of triband flags have a central band that is exactly twice the width of others, a design known as Spanish fess (horizontal) or Canadian pale (vertical). On some flags, this is not the central band, such as for Colombia or Rwanda.
Pan-African
Flags in the pan-African family use a combination of some or all of the colors red, yellow, green, and black. Some pan-African flags also have white and, less commonly, blue, but these are not considered pan-African colors. The designs of flags in this family vary considerably. The colors red, yellow, and green became associated with pan-African colors through the Ethiopian flag. Black was later added by Marcus Garvey, an activist and organizer for the first black unification movement in the United States. Inspired by the pan-African colors' growing association with post-colonial independence, many countries in the Caribbean and the Guianas with large populations in the African diaspora also adopted pan-African colors.
Ethiopian flag family
The colors green, yellow, and red have been historically important in Ethiopia since the early 17th century. Along with Liberia, Ethiopia was the only currently existing nation to avoid European colonization during the scramble for Africa. Its flag, therefore, was the inspiration for many countries that gained independence after colonization. The modern flags of Bolivia, Lithuania, and Myanmar also use these three colors, but their origins are unrelated to the Ethiopian flag.
Marcus Garvey and Theodosia Okoh families
The Jamaican pan-Africanist leader Marcus Garvey inspired two independent sets of national African flags. In 1917, he proposed a red, black, and green flag for his organization, known as the Universal Negro Improvement Association and African Communities League. According to Garvey,
These three colors were the inspiration behind the flag of Kenya, the flag of Malawi, the Flag of South Sudan and other historic flags such as the flag of Biafra. Independently, Marcus Garvey also created the Black Star Line, a shipping company between the United States and West Africa that transported many African-Americans to Africa and vice versa. The eponymous black star of the house flag of the company later became a part of three national flags in West Africa, starting with the flag of Ghana designed by Theodosia Okoh.
Pan-Arab colors
The pan-Arab flag family is a set of flags featuring three or four of the colors red, black, white, and green. The flags have three horizontal stripes, often with an emblem in the center or an overlapping shape in the hoist. According to biographers of Muhammad, he used both flags of white and flags of black. Each color of the pan-Arab flags is associated with a caliphate of Islam. White and black flags were used by the Umayyad and Abbasid dynasties respectively. Although green is often identified as the color of the Fatimid dynasty by vexillological sources, that is not correct: their dynastic color was white. Green is now considered the color of Islam. Red was the color of the Hashemites. These colors were also described by the 14th-century Iraqi poet Safi al-Din al-Hilli: "White are our deeds, black are our battles, green are our ranches, red are our swords."
In 1911, members of a Turkish literary club chose these four colors as the colors of the modern Arabic flag. The colors were combined in the flag of the Arab Revolt in 1916, and many countries adopted these colors as the colors of their national flags upon gaining independence from the Ottoman Empire at the end of World War I.
Iranian colors
Iran adopted a flag with green, white, and red stripes in the mid-19th century. The flag has undergone changes since, but the three stripes remain. When the newly independent republic of Tajikistan changed its flag from its former Soviet version, it chose to use the same stripes in reverse order as a nod to its close cultural ties with neighbouring Iran. The flag of Kurdistan, a geo-cultural region overlapping with Iran, uses the green-white-red stripes of the Iran flag charged with a yellow sun.
Gran Colombia
The Gran Colombia flag family is made up of flags of countries in the South American former area of Gran Colombia. They have three horizontal stripes of yellow, blue, and red. Venezuelan revolutionary leader Francisco de Miranda personally designed the flag of Gran Colombia, a historic state that included modern Colombia, Ecuador, Panama, Venezuela, and parts of Brazil and Guyana. The flag of Gran Colombia had three colours signifying Hispanic America (yellow), the Atlantic Ocean (blue), and "bloody Spain" (red). Miranda attributed the inspiration for these colors to a late-night conversation with the German writer and color theorist Johann Wolfgang von Goethe, who is described as saying
The flag of Gran Colombia was first hoisted in 1806. It led to the current designs of Colombia, Ecuador, and Venezuela.
Belgrano
The Belgrano flag family is composed of flags of Central and South America with blue and white stripes. In 1812, the Argentine revolutionary general Manuel Belgrano raised a flag in Rosario, Argentina, of three horizontal stripes of blue-white-blue. It was formally adopted by the Government of Argentina in 1816. Six years later, commander-general of El Salvador Manuel José Arce took the "Argentine colours of Belgrano" as a new national flag of that province, becoming the first additional flag of the family. Building on this, the flag of the Federal Republic of Central America had blue and white stripes, and all of the countries that were once part of that republic retain those stripes in some way in their flags. El Salvador and Nicaragua have also retained the triangular emblem of the former republic; the flag of Costa Rica has an additional red stripe. Argentina's and Uruguay's flags now have the Sol de Mayo.
Red banner
The red banner flag family is the family of flags that use large red fields or red stars as symbols of communism. The color red became associated with revolution when it was adopted by the Jacobins during the early days of the French Revolution as a symbol of their willingness to shed blood for their cause. After being used by the Paris Commune in 1871, the color became closely associated with socialism. The Bolsheviks used these flags as inspiration during the Russian Revolution, adopting the flag of the Soviet Union upon their victory in 1922. As a result, the color red became more closely associated with communism than socialism. The flag also featured a hammer and sickle and a red star fimbriated by gold, two symbols that also became closely associated with communism. As communism spread during the 20th century, many countries, especially in Asia and Africa, adopted red flags and stars to symbolize their support for the political movement. Every former Soviet state once flew red banners. All but Belarus, which simply removed the traditional communist hammer and sickle, has adopted a different flag since the fall of the Soviet Union. Similarly, the current flag of Mongolia removed the communist star from its flag in 1992, but kept all of the other elements.
Trucial States
Trucial State flags are a flag family from the southern and eastern coasts of the Persian Gulf. They consist of red flags with white stripes, cantons, or borders. Red is a traditional color of the Kharijite Muslims who lived in this region, and they historically used all-red banners. It was the British who added the white to the flags of the region. When the region became a British protectorate in 1820, the treaty drafted by the United Kingdom said
Instead of borders, most of the states adopted a stripe. Nearly all of these states are now member emirates of the United Arab Emirates. While the flag of the United Arab Emirates is not a Trucial States flag, the flags of the individual member emirates still are. In the 1930s, the independent countries within the Trucial State flag family, Bahrain and Qatar, both adopted serrated edges from their earlier straight-edge designs. The flag of Qatar is unique in the Trucial State flag family for having a darker shade of red or maroon, a color made using traditional shell-based dye from the area.
United Nations
The United Nations flag family includes the flag of the United Nations and subsequent flags that borrowed design elements from the flag including the colors, symbols, or both. The UN adopted its emblem and flag in 1947. The flag came to represent the neutrality and cooperation of the UN, so similar flags are often adopted for regions in states of conflict or instability. The first such national flag was the flag of Eritrea from 1952 to 1962, which symbolized peace between the Christians and Muslims in the newly formed country. The current Eritrean national flag, adopted in 1993, has less of the UN blue, but still retains the UN olive branches from the first design. The flag of Cyprus, adopted 1960, has no UN blue, but has the laurel wreath and a map as the central emblem. Most national flags inspired by the UN's were flags of United Nations trust territories, colonies that transitioned to independence with support and administration from the UN. These include the flag of the Trust Territory of the Pacific Islands (which later inspired the flags of Micronesia and the Northern Mariana Islands) the flag of the Trust Territory of Somaliland (which is the design of the current flag of Somalia), and the Flag of the United Nations Transitional Authority in Cambodia (which was replaced by the current flag of Cambodia that is not in the UN flag family).
References
Types of groupings
National symbols
Vexillology | Flag families | [
"Mathematics"
] | 3,035 | [
"Symbols",
"Flags"
] |
72,095,612 | https://en.wikipedia.org/wiki/Death%20of%20Cindy%20James | Cynthia Elizabeth James (née Hack; June 12, 1944 June 2—June 8, 1989) was a Canadian nurse who disappeared from Richmond, British Columbia, on May 25, 1989. She was found deceased approximately two weeks later in the yard of an abandoned house, hogtied and with a nylon stocking wrapped around her throat. An autopsy indicated that she had died of an overdose of morphine, diazepam, and flurazepam. James's death was notable as she had made numerous reports to authorities dating back to 1982, alleging that she had been a victim of various acts of stalking, harassment, vandalism, home invasions, and physical attacks perpetrated by an unknown assailant.
James's death and prior allegations were subject of great dispute, as the Royal Canadian Mounted Police (RCMP) were unable to find any evidence suggesting she had been an actual victim of a stalker. Furthermore, she had a documented medical history of depression and suicidal thoughts, leading authorities to suspect that she may have been fabricating the various attacks and other incidents herself, orchestrating them to appear as legitimate, culminating in an eventual staged suicide. Over the nearly seven-year period James reported the incidents, the RCMP allocated an estimated $1–1.5 million in funds to investigate her claims, marking one of the longest and most costly police investigations in British Columbia history.
Despite skepticism from authorities, James's family members publicly insisted that she had in fact been preyed upon, and eventually murdered. A coroner's inquest was held in the spring of 1990 which included testimony from more than 80 witnesses. The inquest ultimately resulted in the conclusion that James had died of an "unknown event."
James's death received international media coverage and was the subject of an Unsolved Mysteries segment in 1991. Furthermore, two different books were published in 1991 chronicling her life and death: Who Killed Cindy James by British journalist Ian Mulgrew, and The Deaths of Cindy James by Neal Hall, a Canadian crime reporter who had extensively covered James's case for the Vancouver Sun. In 2021, a podcast on James, Death by Unknown Event, narrated by Pamela Adlon, was released by Audible.
Background
Cynthia Elizabeth Hack was born in Oliver, British Columbia, Canada, on June 12, 1944, to Matilda "Tilley", a homemaker, and Otto Hack, an English teacher and former colonel in the Royal Canadian Air Force. Both of her parents were of Russian descent. She was one of six children, with three older brothers and two younger sisters. Cindy spent part of her teenage years in Ottawa due to her father's involvement in the air force, and attended high school there. She recorded in her private diaries that her childhood had been marked by her father's strictness, which included corporal punishment.
In adulthood, Cindy pursued a nursing career in Vancouver, and enrolled in nursing school in 1962. During this period, her father had reenlisted with the air force and relocated the family to France, where she visited them during holidays. During this time, in letters to her family, Cindy occasionally referred to an unnamed intern she had met during her studies. She claimed that the two had at one point been engaged, and that, after finding he had terminal cancer, the man committed suicide while the couple were on a skiing trip. None of her parents or siblings, however, ever met the man, and Cindy did not name him.
In the summer of 1965, Cindy met Roy Makepeace, a South African psychiatrist 18 years her senior. The two married on December 9, 1966, the same year she graduated from nursing school with a BSN. Cindy's parents were skeptical of the marriage due to the couple's age difference, and her father felt that Makepeace had taken advantage of Cindy's "naiveté and gullibility." Her family testified that the couple's marriage was troubled and that the two were at times emotionally distant. Though Cindy later made accusations of spousal abuse, Makepeace asserted he "only slapped her twice" over the course of their marriage. Though licensed as a psychiatrist in his home country of South Africa, Makepeace failed twice to obtain his medical license in Canada and instead accepted a job as an Assistant Professor in the Faculty of Medicine at the University of British Columbia.
Cindy worked as a pediatric nurse at Vancouver General Hospital—where her husband had also one time been employed—from 1966 to 1975. In 1973, Makepeace took a job as director of health services at BC Hydro. In April 1975, Cindy was hired as a team coordinater at Vancouver's Blenheim House, a facility caring for children with behavioral disorders. She worked at Blenheim House for approximately 12 years, and was noted by her colleagues for her competence and professionalism.
Allegations of harassment
Spanning a nearly seven year-period between 1982 and 1989, Cindy reported approximately 90 incidents of criminal activity to the Royal Canadian Mounted Police (RCMP). Her claims included alleged acts of stalking, vandalism, arson, harassment, intimidation, home invasions, and physical assaults perpetrated by an unknown person or persons.
1982
The incidents began in September 1982, four months after Cindy separated from Makepeace. In late September, she told friends and family members she suspected that a prowler had been lurking around her home. A series of obscene phone calls soon followed, the first of which was received on October 7, 1982. Cindy's mother relayed that, though she was reluctant to discuss her experiences, she indicated that the phone calls consisted of an individual speaking in different voices, and that, on some occasions, there was mere silence on the other end of the line. Cindy described some of the calls as sexual and violent in nature.
On October 11, Cindy received a phone call consisting of loud breathing noises, and the following day, received another call in a menacing whisper, which said: "I'll get you one night, Cindy." She reported the obscene calls to the RCMP, who visited her home and suggested she keep a list of each call and its contents, as well as get an unlisted number. Shortly after the officer left, Cindy received a call in which an apparent male voice said: "You fucking bitch. I'll get you." The next day, on the afternoon of October 13, the caller threatened her: "So you think calling the police will keep you safe? You wait. I've got my zipper open, I'm talking to my throbbing..." before she abruptly ended the call.
Two days later, Cindy reported to the RCMP that she had heard someone lurking outside her home and awoken in the morning to find her porch lights smashed. On October 15, she reported to police that someone had thrown a rock through one of her windows and entered her house, though nothing else had been disturbed. Four days later, on October 19, she reported that someone had entered her home and slashed a pillow on her bed.
Patrick McBride, a constable with the Vancouver RCMP, suspected the culprit was her estranged husband, Makepeace, who denied involvement. Cindy herself made conflicting statements regarding Makepeace, telling authorities she did not think he was capable of tormenting her, but also divulged to friends and coworkers that he was violently abusive during their marriage. On October 20, two tenants who rented the basement of Cindy's home reported to police that they heard strange noises upstairs on the main floor after she had left for work. A next-door neighbor informed McBride that she had witnessed a man standing outside the house on at least three different occasions, and one time entering the gate of the front yard. The neighbor insisted the man did not resemble Makepeace.
Cindy concurrently began a relationship with McBride, which lasted approximately one year. McBride, who had recently separated from his wife, moved into Cindy's house on October 31, 1982. She told friends that McBride had offered to stay for approximately two weeks, helping surveil in the event that the perpetrator arrived at her home. Several days after McBride moved in, he found Makepeace sitting in his parked car in an alley behind the house. When questioned, Makepeace claimed he was trying to catch Cindy's alleged intruder "in the act," and subsequently left after McBride informed him he had moved in.
In mid-November, McBride stated that he himself received a mysterious phone call at the home while Cindy was present, and that the caller spoke no words. McBride initially suspected the call may have been made from an airport terminal, as he could hear a woman's voice in the background over a public-address system, though it was eventually traced to an exchange in the Vancouver suburb of Richmond. Later in November, Cindy found a note pinned to her car windshield which featured a picture of a corpse lying under a medical sheet. On November 28, McBride observed that the phone lines outside the house had been cut in five different places. Cindy, who remained cordial and friendly with Makepeace despite their breakup, at times invited him to her home with McBride present, as both men had in common a shared fascination with finding her alleged harasser, and would often discuss the case together. McBride moved out of Cindy's home on December 1, though the two continued to casually date, frequently having dinners together in Vancouver and Bellingham, Washington, United States. The week of Christmas 1982, Cindy found a note outside her house reading "Merry Christmas," with a photo of a woman with her throat slashed, stained with red ink.
1983–1984
On the night of January 27, 1983, Agnes Woodcock, a friend and coworker from Blenheim House, visited Cindy's house and found her lying unconscious in her backyard, with a nylon stocking wrapped around her neck. Upon regaining consciousness, Cindy told Woodcock that she had been attacked from behind by an assailant while walking to her exterior garage, and that the individual brought her into the garage, where another male subject waited, and the two strangled her. She alleged that the men inserted a knife into her vagina and threatened to kill her younger sister, Melanie, if she reported the attack to authorities. Doctors who examined Cindy after the alleged attack found no concrete evidence of sexual assault, though Det. David Boywer-Smith remained ambivalent about her claim. At police request, Cindy was asked to see a psychiatrist but declined, as she feared doing so would stigmatize her; instead, she agreed to visit a general practitioner with experience in counseling.
Cindy relocated from her residence to a house in West Vancouver on February 1, 1983. Less than a week later, she received a threatening letter reading: "Run Rabbit Run, I'll show you how fucking good I am. Soon, bang, bang, you're dead." After a rash of further obscene calls, Cindy relocated again to another house in April 1983. Makepeace, who had made continued attempts to reconcile with his wife, showered her with several lavish gifts in the summer of 1983 and paid her airfare to Indonesia so she could visit her brother, Roger, who was stationed there. Several weeks after returning from the trip, Cindy found another note on August 22, which read: "Welcome back—death, blood, hate, etc."
Cindy painted her car a different color in an attempt to conceal her identity, and hired a private investigator, Ozzie Kaban, to help investigate her alleged stalker. She continued to pay for Kaban's services over the following six years. Kaban noted that Cindy went to extensive lengths to protect herself, such as wearing a portable panic button and keeping oil and pepper spray with her at all times. Between October and November 1983, Cindy discovered the remains of three strangled cats in her garden, each bound with rope. In her private diary, she accused Makepeace of destroying the garden in her backyard. She continued to receive numerous phone calls at home and at work, some of which were answered by her coworkers at Blenheim House, who told authorities the caller did not speak.
On January 30, 1984, Kaban overheard strange noises on a two-way radio he had given Cindy, prompting him to visit her home. Upon arrival, he found her lying unconscious on her living room floor with a paring knife stabbed through her hand, and a note pinned through with the knife. The note, which was crafted with letters cut-and-pasted from a magazine, read: "NOW YOU MUST DIE, CUNT." Cindy was taken to a local hospital, and in an interview with Kaban stated the last thing she remembered before being found was witnessing a man coming through the gate to her property before he assaulted her and bludgeoned her over the head with a blunt object. She stated that, once incapacitated, she recalled her attacker inserting a hypodermic needle into her arm. Doctors located a needle mark in her right arm, but found no traces of any drugs in her system. Cindy took a polygraph test after the incident, which purportedly showed no deception; however, the officer who conducted the test later stated that the results, by his estimation, proved "inconclusive." Constable Kiyo Ikoma, who reported to Cindy's residence the night of the alleged attack, stated that he observed blood smeared in circular patterns on the kitchen floor, as though someone had attempted to clean evidence.
In February 1984, detectives began increasingly questioning Makepeace, as Cindy had confided that she felt he was the one tormenting her. In interviews, Makepeace theorized that Cindy's attackers were part of the mafia and connected to her employment at Blenheim House, which often treated children who were wards of the court. In March 1984, Cindy's father Otto met with Makepeace at a doughnut shop in Vancouver wearing a police wiretap, and told Makepeace to cease contact with his daughter. After the meeting, Makepeace wrote and sent a six-page letter to Otto outlining his theory that he believed the mafia was after Cindy, and urged Otto to pressure police to investigate this angle.
Over the summer of 1984, Cindy's reported incidents of harassment reached a "crescendo" in intensity. On June 18, she phoned Kaban in a panic, and he rushed to her home to find her cowering in the garden, claiming someone had infiltrated the house. Kaban discovered her dog, Heidi, cowering in the basement, along with a note reading "Happy Birthday" alongside sexually-explicit photos. Heidi had been physically abused, and Kaban noted that the rope bound around her appeared to be the same discovered on the dead cats Cindy had found the previous autumn. On a windowsill in the basement, a cigarette butt was discovered which did not match the brand Cindy was known to smoke. Based on the physical abuse Heidi had endured, Kaban concluded that Cindy could not have been the perpetrator, stating: "She'd never have done that if she was the Cindy I knew." Over the following several weeks, further calls were received, one of which Kaban answered at Cindy's home while she was at work, and a dead cat was found lying in the stairwell of her house. On July 1, Cindy told Kaban two men had arrived at her front door posing as police officers, but fled when she radioed Kaban. Cindy subsequently reported a series of further obscene calls, one of which consisted of the caller saying: "You're dead, bitch. It's gonna feel good." A coworker of Cindy at Blenheim House also received a call which said: "Get rid of the big pig."
On July 9, 1984, Cindy's mother Tilley spent the night at her home. In the middle of the night, Tilley awoke to Heidi barking, and found Cindy checking windows and doors on the main floor of the house. Moments later, they both heard the doorbell ring, and discovered a window near the front porch cracked in several areas. Two weeks later, on July 23, Cindy claimed she was attacked by an assailant in nearby Dunbar Park while walking her dog at approximate 8:30 p.m. By her recollection, she was assailed by a bearded man driving a green van, with a female passenger. Several hours later, at around midnight, she was found in a dazed state attempting to enter the home of a neighbor, and had a dark-grey nylon stocking around her neck. Her dog Heidi was found by Kaban wandering in the area of the park. She was taken to the nearby University of British Columbia Health and Sciences Centre, where doctors observed two puncture marks in her right arm. While Cindy was being treated, a hospital receptionist told authorities a man with an accent had called the front desk inquiring about the hospital's security policies; when police played audio of Makepeace's voice, the receptionist felt there was a "strong possibility" it was the same person. In October 1984, while under the care of a hypnotherapist, Cindy recounted a repressed memory of witnessing a double murder but did not divulge further details.
1985–1986
Following the July 1984 attack, Cindy continued to receive anonymous phone calls, but none were long enough to be adequately traced by police, and police surveillance of her home proved unfruitful. In January 1985, while under hypnosis, Cindy told police she had witnessed her ex-husband murder a man and woman, then dismember their bodies with an axe while the couple were vacationing at a cabin on Thormanby Island, near Sechelt, in July 1981. According to Cindy, Makepeace smeared blood from one of the victims' severed limbs across her face during the dismemberment. It was later discovered that Cindy's sister, Melanie, was with her on this vacation, and had no recollection of anything sinister occurring.
In late June 1985, Cindy was involuntarily committed to the psychiatric unit at Vancouver's Lions Gate Hospital after having attempted suicide by overdosing on prescription drugs, though she later said she had not intended to kill herself. On July 2, she agreed to allow police to wiretap a phone conversation with Makepeace, during which she accused him of being the source of her problems, and confronted him about the memory she recounted under hypnosis of him murdering two people. During the conversation, Makepeace denied the incidents, deeming Cindy "insane" and involved in an "enormous" revenge fantasy. Following this recorded call, the RCMP employed officers to maintain 24-hour surveillance of Cindy, Makepeace, and two other unnamed suspects over a weeklong period. The surveillance was ultimately terminated after nothing unusual was observed. Authorities further investigated Cindy's claims regarding the alleged dismemberments committed by Makepeace and found no evidence of any murders or missing person cases in the Gulf Islands at the time. Makepeace's attorney stated that the accusation led authorities on a "wild goose chase" searching for the cabin location of the alleged murders, which they were unable to find.
Cindy received a package at her home in early July containing a charcoal-colored nylon stocking, along with a note reading: "Blood flowing freely." Several weeks later, on July 27, she found a cosmetics container on her front porch containing putrefied raw meat from a small animal. On August 5, Cindy called into the police station reporting a fire in her home. Authorities found what appeared to be pieces of burnt newspaper scattered in the room; another fire was reported by Cindy the following day.
On August 21, a third fire broke out in the basement bathroom of Cindy's home at approximately 4:45 a.m. When firefighters and police arrived at the residence, they observed Cindy in a "heated" discussion with private investigator Kaban, explaining that she had taken her dog out for a walk at approximately 3:15 am and returned home to discover the blaze. The window of the bathroom was found partly ajar by authorities, but the soot and dust on the windowsill showed no markings that an intruder had entered or exited through it. Charred remnants of a newspaper were discovered in the bathroom. A detective who investigated the fire later testified that he believed Cindy had started the blaze herself.
In the fall of 1985, Dr. Anthony Marcus, a psychologist, was requested by Carol Halliday of the RCMP to conduct interviews with Cindy and examine the various case files. Halliday, who had become involved with the case after reporting with a colleague at the August 21 fire incident, felt Cindy was lying and orchestrating her attacks, and that the various male officers who investigated them for her had been "conned by the histrionics of a pretty woman." Based on his interviews and analysis of police records, Marcus offered his professional opinion that Cindy may have been suffering from dissociative identity disorder stemming from a traumatic childhood incident, though he did not question Cindy about her early life during their interviews.
On December 1, Cindy relocated to a new house in Richmond. Ten days later, on December 11, at approximately 6:00 p.m., she was found by motorists semiconscious in a ditch approximately from her home, near the University of British Columbia campus. She was wearing men's work boots and a single glove, and again, a nylon stocking was tightly tied around her neck. Due to frigid temperatures, Cindy was suffering from hypothermia and was rushed to a local hospital, where it was suspected she had been injected with some sort of tranquilizer. She also exhibited bruising and various cuts on her body. When interviewed in the hospital, Cindy claimed to have no memory of what occurred, or how she had gotten to the location where she had been found; her last memory was going to have lunch during her workday, after which she stopped at a local pharmacy. Disconsolate over the feeling that police did not believe her, she flew to visit her brother Roger in West Germany for Christmas.
In early 1986, Cindy formally changed her last name from Makepeace, the surname of her ex-husband, to James, hoping to further conceal her identity. To help assuage her fears, her friend Agnes Woodcock, and her husband, Tom, sometimes spent nights at Cindy's home. On April 16, the couple were awoken by Cindy, who stated she heard a commotion in the house. Upon investigating, they found another fire had been started in the basement. When they attempted to phone the fire department, they found the phone was dead. Tom fled across the street to a neighbor's residence to call police, and when exiting the house, claimed to have witnessed a man standing on the street outside the residence; when Tom approached him, the subject fled on foot.
Cindy stayed with the Woodcocks for several days following the fire, where they noted that she refused to eat and made comments that her life was no longer worth living. Allan Connolly, a psychiatrist who had been treating Cindy since January 1983, met with her and stated that, though he had long believed her allegations of harassment, he feared she was suicidal. Connolly had her committed to the psychiatric ward of St. Paul's Hospital for two weeks, where it was observed that she was suffering from anorexia and depression. She was subsequently transferred to Riverview Hospital, where a comprehensive psychological examination was conducted. The report noted:
After a ten-week hospital stay, Cindy was released. According to her father, she told him she had been "withholding information" regarding her alleged attacks, stating that she knew the identity of the assailant but refused to name him.
1987–1989
In August 1987, Cindy began working as a nurse at Richmond General Hospital. On August 28, her home alarm was triggered after a back window was broken, and three days later, on August 31, she reported to police that her front porch lightbulbs had been loosened. The following week, she reported that someone had used a glass cutter to create a hole in the basement door window. In February 1988, Cindy indicated that someone had shattered a window to her home after securing it with electrical tape.
On October 11, 1988, Makepeace received two strange voice messages on his home answering machine. One of the messages contained a hoarse voice speaking the phrase: "Cindy, dead meat soon," while the other stated: "More smack, more downers, another grand after we waste the cunt. No more deal." He gave the answering machine tapes to his attorney, as he distrusted the Vancouver police, whom he felt might target him as a suspect. Fifteen days later, Cindy was found unconscious in her garage. She had been hogtied, was nude from the waist down, and again had a black nylon stocking tied around her neck. Around this time, the RCMP hired mountain climber and knot expert Robert Chisnall to analyze the knots on the nylon stockings she had frequently been found bound with. At the time, Chisnall concluded that it was "highly unlikely" that Cindy would have been able to secure such knots herself.
In January 1989, Richard Johnston, a life insurance salesman from whom Cindy had purchased a policy, moved into the basement unit of her residence; she offered him the rental on the basis that she would feel more safe with someone else living with her. On April 8, a security guard at Richmond General Hospital, where Cindy was employed, discovered a note on the premises crafted with cut-and-pasted letters, which read: "SOON, CINDY". The phrase "sleep well" was also found written in the dew on her windshield. Following a reported attempted break-in at her home on April 29, the RCMP used scent hounds in an attempt to track the alleged intruder, but the dogs found no trail. On May 10, 1989, scent hounds were utilized again following another alleged break-in, and were able to track the scent of an unknown individual that led over the backyard fence of Cindy's home.
RCMP conclusions
Over the course of the nearly seven years that Cindy had reported the various incidents, the RCMP spent an estimated CA$1–1.5 million of resources investigating her claims, but no evidence could be located to corroborate them. Because of this, authorities suspected that Cindy was inventing the incidents herself, and staging them to appear as though she were the victim of a violent stalker. Cindy expressed frustration with the police department, aside from one detective, Jerry Anderson. In a complaint she filed against the RCMP for her perceived dismissal by several officers, she positively singled out Anderson "for his patience, unfailing professional conduct and his exemplary investigation of this case... He is the only member of the RCMP I feel I can trust and be comfortable with."
Disappearance
At approximately 4 p.m. on May 25, 1989, Cindy picked up her paycheck from Richmond General Hospital. There, she spoke with a coworker, who reported that she seemed to be in good spirits, and said Cindy informed her she had not experienced any suspicious activity at her home for at least two weeks. Cindy was last seen several hours later purchasing groceries at a Safeway supermarket and visiting a Bank of Montreal at the Blundell Shopping Centre. A bank patron told police they had stood in line behind Cindy at the bank's ATM, where she deposited her paycheck at approximately 7:59 pm.
That same day, Cindy had scheduled to have an infrared detection system installed in her home for security purposes, and had planned for her friends Agnes and Tom Woodcock to play bridge and spend the night. After not hearing from Cindy, the Woodcocks visited her home at approximately 10:00 pm, and found the house locked and Cindy's Chevrolet Citation absent. They briefly spoke with Johnston, who informed them she had mentioned earlier that she was going to do some shopping. The Woodcocks drove past the Blundell Shopping Centre which they knew Cindy to frequent and found her car abandoned in the lot. They proceeded to drive to the Richmond RCMP station to report Cindy as a missing person. Though she had only been missing for several hours, a patrol car was sent to investigate based on her extensive history with the police department.
Upon examination of the vehicle, blood was located inside the car on the driver's side door as well as groceries and a wrapped birthday gift for her friend's young son; contents from Cindy's wallet were found lying underneath the vehicle. A subsequent inspection of her home that night showed nothing had been disturbed: police observed that the house was orderly and clean, and filled with numerous "well-tended" houseplants. The Canadian Coast Guard deployed searches of rivers in the area, as well as the Gulf of Georgia, in an attempt to locate the missing woman.
Several days after Cindy was reported missing, her tenant, Johnston informed police he had received a call at his office from a man claiming to be her father, inquiring about her life insurance policy. Johnston's secretary informed the caller that he would need to visit the office, as private insurance matters could not be relayed over the phone. When authorities questioned Cindy's father, he denied ever making the phone call.
Death
On June 8, 1989, Gordon Starchuck, a municipal paving worker, discovered Cindy's body in the backyard of an abandoned house at 8111 Blundell Road, Richmond. Her body was hogtied with rope in a fetal position, and a black nylon stocking was bound tightly around her neck. Cindy's right leg lay beneath a bramble of blackberry bushes, and her coat was found lying near her body. The property where her remains were found was situated along a busy street near an intersection, which had frequent foot traffic from pedestrians. On the residence's exterior fuel tank, police found a graffito in orange spray paint reading: "Some bitch died here." A line, spray-painted along the ground with the same orange paint, ran from the fuel tank to the spot where her body lay, encircling it. Inside the abandoned home, another spray-painted graffito reading "Devil" was found.
Sheila Carlyle, a pathologist who examined Cindy's body at the scene, noted that her hands had been bound so tightly that one finger had scratched another down to the bone. A pinprick consistent with a hypodermic needle was located on the inner-right elbow of the body. Based on insect and larvae activity on the remains, forensic entomologist Gail Anderson concluded that the body had begun the decomposition process at the site where it was found as early as June 2, 1989.
An autopsy determined that Cindy had died of multiple drug intoxication from substantial amounts of morphine, diazepam, and flurazepam. Her blood toxicology report showed that she had ten times the lethal dose of morphine in her bloodstream. Based on an examination of her stomach contents, toxicologist Heather Dinn reported that Cindy had orally ingested approximately twenty 30-milligram tablets of flurazepam (or up to eighty tablets of a higher dose), in addition to numerous tablets of diazepam, a combination that itself was lethal. The method by which the morphine had been administered could not be determined, "baffling" the pharmacologist who analyzed the toxicology report. Traces of morphine were found in Cindy's stomach, though Dr. John McNeill stated that the amount could have resulted from intravenous injection of the drug. By McNeill's analysis, if Cindy had received the morphine via intravenous injection, she would have been rendered unconscious within mere minutes, and would have died within several hours. It was ultimately concluded by authorities that the overdose had been "so large that there was no reliable estimate of how long Cindy could have remained functional."
The RCMP suspected Cindy's cause of death was likely a suicide or accident, based on the assumption that she had fabricated her numerous prior claims of assaults and stalking, and this was quickly reported by several local tabloid news outlets. Her personal private investigator, Kaban, visited the morgue to examine her body on June 10 and observed that her remains exhibited lividity—the settling of blood postmortem, visible on the skin—on the left side of her body. Because her body had been found lying on its right side, Kaban felt that she may have died elsewhere, and that her body was relocated to the site where it was ultimately discovered.
A memorial service was held for Cindy on June 14, 1989, two days after what would have been her forty-fifth birthday. Police surveilled the memorial service using hidden cameras, capturing the faces and license plates of all who attended. Her ex-husband, Makepeace, was not in attendance. In the summer of 1989, the abandoned house where Cindy's body was discovered was demolished.
Coroner's inquest
An extensive inquest into Cindy's death was undertaken in the spring of 1990 in Burnaby, which consisted of five jurors and featured testimony from over eighty witnesses. The inquest was originally scheduled to run three weeks, but upon it "progressing much slower than expected," an additional twenty-one days were added. The inquest, which totaled forty days, was the longest and most expensive in British Columbia at that time.
Among the evidence presented were the two recorded phone messages Makepeace had received on his answering machine. During his testimony on the stand, Makepeace made various accusations against Cindy's family, alleging that her father had physically abused her throughout her childhood and that one of her brothers had molested her. He also accused the police of attempting to frame him. It was also revealed that, shortly after her death, Cindy's parents uncovered a hoard of various medications in her home (including sedatives and antipsychotic drugs) prescribed by her psychiatrists, which they disposed of by flushing down the toilet. Her younger sister, Melanie, also found a glass cutter in Cindy's purse along with a medical syringe kit, a urinary catheter, and saline solution in her bedroom.
Jurors were presented with graphic footage of Cindy's decomposing corpse as it was discovered at the scene, as well as numerous accounts detailing her mental state leading up to her death. Testimony was provided from several psychiatrists and psychologists, including those who had personally treated Cindy over the years. Dr. Paul Termansen testified that he believed she suffered from hysterical personality disorder, while Dr. Wesley Friesen—a longtime psychiatrist of Cindy's—stated he suspected she had borderline personality disorder with elements of post-traumatic stress disorder. By Friesen's account, Cindy possessed a "tremendous amount of rage" toward her father and, based on their numerous sessions, Friesen believed there was a "strong likelihood" that her father sexually abused her when she was a child, though she never indicated this to be the case.
Attempts to discern whether or not Cindy could have bound herself in the state she was discovered were also focused on during the inquest: using the same length of nylon found binding her body, knot expert Robert Chisnall demonstrated in court how she could have bound herself within a three-minute timeframe, before the effects of the narcotics in her system would have taken effect.
The inquest concluded on May 25, 1990, exactly one year after Cindy had disappeared. After deliberations, the jury was unable to determine whether her manner of death was suicide, homicide, or accidental. It was ultimately ruled that Cindy had died of an "unknown event," and the case was formally closed.
Media representation
Cindy's disappearance was profiled on the American series A Current Affair prior to her discovery, and her case was later profiled in a February 1991 episode of the NBC series Unsolved Mysteries. A docuseries was released the same month in Canada via BCTV. Two books chronicling her life, stalking allegations, and death were also published in 1991: The Deaths of Cindy James by Canadian journalist Neal Hall, and Who Killed Cindy James? by British journalist Ian Mulgrew. In September 2021, an Audible-produced podcast on James' death, entitled Death by Unknown Event, was released, featuring narration by actress and writer Pamela Adlon.
See also
List of solved missing person cases
List of unsolved deaths
Notes
References
Sources
1980s missing person cases
Deaths by person in Canada
Drug-related deaths in Canada
Formerly missing people
June 1989 events in Canada
May 1989 events in Canada
Missing person cases in Canada
Stalking
Unsolved deaths in Canada
Violence against women in British Columbia | Death of Cindy James | [
"Biology"
] | 7,548 | [
"Behavior",
"Aggression",
"Stalking"
] |
72,096,190 | https://en.wikipedia.org/wiki/Triptonide | Triptonide is a chemical compound found in Tripterygium wilfordii, a plant used in traditional Chinese medicine. A 2021 trial in mice and monkeys suggested that triptonide may offer a reversible male contraceptive.
References
Heterocyclic compounds with 7 or more rings
Epoxides
Lactones
Isopropyl compounds
Ketones
Contraception for males | Triptonide | [
"Chemistry"
] | 77 | [
"Ketones",
"Functional groups"
] |
72,097,781 | https://en.wikipedia.org/wiki/Chiral%20thin-layer%20chromatography | Chiral thin-layer chromatography is a variant of liquid chromatography that is employed for the separation of enantiomers. It is necessary to use either
a chiral stationary phase or
a chiral additive in the mobile phase.
The chiral stationary phase can be prepared by mixing chirally pure reagents such as L-amino acid, or brucine, or a chiral ligand exchange reagent with silica gel slurry, or by impregnation of the TLC plate in the solution of a chiral reagent.
The principle can also be applied to chemically modify the stationary phase before making the plate via bonding of the chiral moieties of interest to the reactive groups of the layer material.
See also
Chiral column chromatography
References
Chromatography
Stereochemistry | Chiral thin-layer chromatography | [
"Physics",
"Chemistry"
] | 175 | [
"Chromatography",
"Separation processes",
"Stereochemistry",
"Space",
"Stereochemistry stubs",
"nan",
"Analytical chemistry stubs",
"Spacetime"
] |
72,097,953 | https://en.wikipedia.org/wiki/Dudley%20Dix | Dudley Dix is a yacht designer, of South African origin, now based in Virginia Beach, US. He graduated from the Westlawn School of Yacht Design. He is notable for having developed the "radius chine plywood" method as a basis for boat construction. Dix won the 1979 Cruising World Design Competition.
Dix has designed yachts of many types (such as monohulls, catamarans and trimarans) employing a variety of materials for the hulls (such as steel, aluminium and wood/epoxy composites). His building methods include cold moulding and radius chine plywood. The radius chine plywood method was developed by Dix himself, and many of his designs use this procedure. The radius chine plywood method enables fast, cheap construction of relatively lightweight vessels. Dix is particularly concerned that his designs are fully seaworthy.
Dix has built many of his own designs for his personal use, including the Didi 38 "Black Cat" which he sailed from 1995 until 2000 (including three crossings of the South Atlantic).
One of Dix's larger designs is the 55' DH550 ocean-going cruising catamaran, such as "Friends Forever" (built by Jean-Jacques Provoyeur and Richard Bertie).
See also
Dudley Dix interview
References
External links
Living people
Naval architecture
1949 births | Dudley Dix | [
"Engineering"
] | 284 | [
"Naval architecture",
"Marine engineering"
] |
72,098,316 | https://en.wikipedia.org/wiki/Ts8 | Ts8 (also known as: TsK2, Tityustoxin K-beta, TsTX-K beta or TsTx-Kβ) is a neurotoxin present in the venom of the Brazilian yellow scorpion, Tityus serrulatus. Ts8 is a selective inhibitor of the voltage-gated potassium channel Kv4.2
Etymology and Source
The neurotoxin Ts8 can be derived from the venom from the Brazilian yellow scorpion, Tityus serrulatus (Ts). This scorpion is predominantly found in Brazil. Alternative names for the Ts8 toxin are TsK2, Tityustoxin K-beta, TsTX-K beta and TsTx-Kβ.
Chemistry
Ts8 belongs to the β-KTx family 1. Toxins in this family contain about 59-75 amino acid residues and three disulfide bridges. There are two-domain peptides; the N-terminal helical domain (NHD) and the C-terminal CSαβ domain (CCD). The CCD is responsible for the neurotoxic activity.
Ts8 contains 60 amino acid residues and the three disulfide bridges that were already mentioned. It has a molecular weight of 6716 Da. Its amino acid sequence is as follows:
K-L-V-A-L-I-P-N-D-Q-L-R-S-I-L-K-A-V-V-H-K-V-A-K-T-Q-F-G-C-P-A-Y-E-G-Y-C-N-D-H-C-N-D-I-E-R-K-D-G-E-C-H-G-F-K-C-K-C-A-K-D
Target
Ts8 selectively and reversibly inhibits the voltage-gated potassium channel Kv4.2. Maximal block of the peak current is 65%. Kv4.2 channels are found in a variety of tissues, including high levels in the brain and heart.
Purified recombinant Ts8 was present in three forms, of which Ts8-FragII has a small inhibitory effect on the Kv1.3 channel.
Mode of action
The inhibition caused by the neurotoxin Ts8 on Kv4.2 channels increases with repeated activation of the channel in the presence of the toxin. In addition the channels inactivated more rapidly, suggesting that the toxin has a preference to bind to the inactivated state of the Kv4.2 channels.
Ts8 does not have pore-forming activity.
Toxicity
In mice, Ts8 increases earlier nociception with higher doses. Elimination or inhibition of Kv4.2 channels via intraplantar injections was seen to induce hypersensitivity to mechanical stimuli. Via intrathecal injection this effect was prolonged and a prolongation plateau of mechanical hypersensitivity was observed. Thus Ts8 can enhance sensitivity to tactile- and mechanical stimuli in mice, by inhibition of the Kv4.2 channels. The symptoms caused by Ts8 induce hyperalgesia, intense and persistent pain.
Ts8 is toxic to human erythrocytes type A+ in concentrations above 2.89 μM.
Treatment
A sting by Tityus serrulatus is treated with a scorpion antivenom serum. This serum, Soro antiscorpionico, containing a human antibody fragment, neutralizes most of the entire venomous cocktail of neurotoxins.
Therapeutic use
In a study from Cordeiro et al (2022) they expressed recombinant Ts8 (rTs8) in Pichia pastoris yeast to be able to evaluate the peptide expression under different conditioning. They looked at the native Ts8 and recombinant Ts8, rTs8-FragI and rTs8-FragII. These forms were all evaluated by an antimicrobial assay. This resulted in growth inhibition of P. pastoris. The native form of the toxin had a larger inhibitory effect than the recombinant forms.
The study from Oliveira et al (2022) showed the antimicrobial activity of Ts8. Here they tested the native Ts8 against different types of microorganisms;
Gram-positive bacteria: Micrococcus luteus
Gram-negative bacteria: Escherichia coli
Yeast: Candida albicans
Filamentous fungus: Aspergillus niger
Ts8 had antimicrobial activity for all of these microorganisms. Ts8 has the strongest effect on gram-negative bacteria, and the lowest effect on both the yeast and the filamentous fungus. This testing was an initial screening to be able to expand the spectrum of action of this toxin. As mentioned before, Ts8 can be toxic for human erythrocytes. The concentration of the antimicrobial assay on Escherichia coli is lower than what is toxic for the human erythrocytes, 1.45 μM. Thus it can be concluded that Ts8 potentially can be used as an antibiotic against E. coli.
See also
Tityustoxin
TsIV
References
Neurotoxins
Ion channel toxins
Tityus serrulatus venom toxins | Ts8 | [
"Chemistry"
] | 1,107 | [
"Neurochemistry",
"Neurotoxins"
] |
72,098,995 | https://en.wikipedia.org/wiki/Double-knot%20toxin | Double-knot toxin (DkTx), also known as Tau-theraphotoxin-Hs1a or Tau-TRTX-Hs1a, is a toxin found in the venom of the Chinese Bird spider (Ornithoctonus huwena or Cyriopagopus schmidti), a tarantula species primarily living in the Guangxi province of China. This toxin, characterized by its bivalent structure of two Inhibitor Cysteine Knots (ICK), is thought to induce excruciating and long-lasting pain by activating the transient receptor potential vanilloid 1 (TRPV1) channel.
Etymology
The name of DkTx is based on its molecular structure, consisting of two ICK segments, connected via a linker.
Chemistry
DkTx can be purified from the venom of the Chinese bird spider Ornithoctonus huwena using reversed-phase chromatography. DkTx is a cysteine-rich peptide; such peptides are difficult to synthesise because of their low folding efficiency. This is why structural and functional information about these peptides is limited. DkTx is a 75-amino-acid-peptide consisting of two independently folded head-to-tail ICK domains, which are linked together via a seven amino acid long linker peptide. This compact and rigid structure provides the toxin with a high affinity to bind to its target channel. The linker provides the separation of the two knots and allows them to dock to the channel binding sites concomitantly. The two ICK-motifs are referred to as K1 and K2, and each of them consists of six cysteine residues. For this reason, DkTx is part of the ICK peptide family; however its DNA sequence diverges from other ICK peptides, such as the vanillotoxins, huwentoxins or hanatoxin.
Target
DkTx is a specific TRPV1 receptor agonist and acts as a bivalent ligand, which gives it high affinity to its target. The TRPV1 channel is a member of the group of TRP ion channels, which are all known to be responsible for sensory signaling, such as mechanosensation, thermoception, and nociception. TRPV1 itself is a nonselective cation channel located in the plasma membrane of nociceptive dorsal root ganglions. It can be activated in several ways, such as by noxious heat, capsaicin, extracellular proteins, and other inflammatory agents. However, binding locations can differ, e.g., capsaicin does not bind to the outer pore region but to the S3-S4 region of the channel.
The potency of this toxin binding to the TRPV1 channel, as quantified with the half maximal effective concentration (EC50) of DkTx is 0.23 μM. Owing to its bivalent structure, this potency is much higher compared to single K1 and K2 motifs or other vanillotoxins binding to the TRPV1 channel.
Vanillotoxins (VaTx, or Vanilloids) are toxins that are TRPV1 agonists that target the channel on its outer pore region. For this reason, DkTx is considered a vanillotoxin. Different from the reversible interaction of the other three VaTx toxins (VaTx1, VaTx2 and VaTx3), binding of DkTx is irreversible and inflicts persistent TRPV1 channel activity.
Mode of action
The bird spider O. huwena produces a large amount of toxins which, although often characterized by the presence of ICK motifs, widely differ in their mode of action. Molecularly, the toxin specifically targets the TRPV1 receptor on the outer edge of the outer pore region of the channel. After binding, DkTx will interact with the membrane and insert its hydrophobic residues into the membrane by forming a complex consisting of the membrane and the toxin, which consequently will lock the TRPV1 channel in the open state.
Toxicity
Upon binding, the toxin is suggested to induce a prolonged sensation of severe pain, accompanied with neurogenic inflammation due to enduring TRPV1 activation. However, specific behavioural effects remain unknown. In line with the isolated toxin effect, the toxic effects of the crude venom are reported to be mainly nociceptive and inflammatory, but not lethal.
References
Ion channel toxins
Invertebrate toxins
Neurotoxins | Double-knot toxin | [
"Chemistry"
] | 959 | [
"Neurochemistry",
"Neurotoxins"
] |
67,685,236 | https://en.wikipedia.org/wiki/Haline%20contraction%20coefficient | The Haline contraction coefficient, abbreviated as β, is a coefficient that describes the change in ocean density due to a salinity change, while the potential temperature and the pressure are kept constant. It is a parameter in the Equation Of State (EOS) of the ocean. β is also described as the saline contraction coefficient and is measured in [kg]/[g] in the EOS that describes the ocean. An example is TEOS-10. This is the thermodynamic equation of state.
β is the salinity variant of the thermal expansion coefficient α, where the density changes due to a change in temperature instead of salinity. With these two coefficients, the density ratio can be calculated. This determines the contribution of the temperature and salinity to the density of a water parcel.
β is called a contraction coefficient, because when salinity increases, water becomes denser, and if the temperature increases, water becomes less dense.
Definition
Τhe haline contraction coefficient is defined as:
where ρ is the density of a water parcel in the ocean and S is the absolute salinity. The subscripts Θ and p indicate that β is defined at constant potential temperature Θ and constant pressure p. The haline contraction coefficient is constant when a water parcel moves adiabatically along the isobars.
Application
The amount that density is influenced by a change in salinity or temperature can be computed from the density formula that is derived from the thermal wind balance.
The Brunt–Väisälä frequency can also be defined when β is known, in combination with α, Θ and S. This frequency is a measure of the stratification of a fluid column and is defined over depth as:
.
The direction of the mixing and whether the mixing is temperature- or salinity-driven can be determined from the density difference and the Brunt-Väisälä frequency.
Computation
β can be computed when the conserved temperature, the absolute salinity and the pressure are known from a water parcel. Python offers the Gibbs SeaWater (GSW) oceanographic toolbox. It contains coupled non-linear equations that are derived from the Gibbs function. These equations are formulated in the equation of state of seawater, also called the equation of seawater. This equation relates the thermodynamic properties of the ocean (density, temperature, salinity and pressure). These equations are based on empirical thermodynamic properties. This means that the properties of the ocean can be computed from other thermodynamic properties. The difference between the EOS and TEOS-10 is that in TEOS-10, salinity is stated as absolute salinity, while in the previous EOS version salinity was stated as conductivity-based salinity. The absolute salinity is based on density, where it uses the mass off all non-H2O molecules. Conductivity-based salinity is calculated directly from conductivity measurements taken by (for example) buoys.
The GSW beta(SA,CT,p) function can calculate β when the absolute salinity (SA), conserved temperature (CT) and the pressure are known. The conserved temperature cannot be obtained directly from assimilation data bases like GODAS. But these variables can be calculated with GSW.
Physical examples
β is not a constant, it mostly changes with latitude and depth. At locations where salinity is high, as in the tropics, β is low and where salinity is low, β is high. A high β means that the increase in density is more than when β is low.The effect of β is shown in the figures. Near Antarctica, ocean salinity is low. This is because meltwater that runs off Antarctica dilutes the ocean. This water is dense, because it is cold. β around Antarctica is relatively high. Near Antarctica, temperature is the main contributor for the high density there. Water near the tropics already has high salinity. Evaporation leaves salt behind in the water, increasing salinity and therefore density. As water temperatures are a lot higher, density in the tropics is lower than around the poles. In the tropics, salinity is the main contributor to density.
References
Oceanography | Haline contraction coefficient | [
"Physics",
"Environmental_science"
] | 882 | [
"Oceanography",
"Hydrology",
"Applied and interdisciplinary physics"
] |
67,685,544 | https://en.wikipedia.org/wiki/Floating%20suspension%20bridge | A floating suspension bridge is a type of suspension bridge supported by towers built on floating pontoons which are tethered to the seabed. The design is intended to overcome the difficulties of building suspension towers in locations where the water is particularly deep. no such bridges have been built, but a project is underway to build one in Norway, at Bjørnafjord, designed by engineer Ian Firth.
See also
Floating cable-stayed bridge
Cable-stayed suspension bridge
Intercontinental and transoceanic fixed links
List of straits
Strait of Gibraltar
Straits of Tiran
References
Further reading
Floating suspension bridges - Long span bridges - Research - Structural Dynamics - Department of Structural Engineering - NTNU
https://www.vegvesen.no/vegprosjekter/ferjefriE39/konferanse/teknologidagene2015/_attachment/1023556?_ts=14ff54620d0&fast_title=11+-+Johannes+Veie++Presentation+of+TLP-concept+Teknologidagene.pdf
Bridges by structural type
Structural engineering | Floating suspension bridge | [
"Engineering"
] | 234 | [
"Structural engineering",
"Civil engineering",
"Construction"
] |
67,685,666 | https://en.wikipedia.org/wiki/Jonas%20C.%20Peters | Jonas C. Peters (born 1971 in Chicago, Illinois) is the Bren Professor of Chemistry at the California Institute of Technology and Director of the Resnick Sustainability Institute. He has contributed to the development of catalysts and photocatalysts relevant to small molecule activation.
Early life and education
Peters was born in 1971 in Chicago, Illinois. He received his Bachelor of Sciences from the University of Chicago in Chemistry in 1993. While an undergraduate student, he worked under Gregory L. Hillhouse on synthetic methods in inorganic chemistry, specifically with regard to the stabilization of reactive species including diazene and nitroxyl. Following his undergraduate, Peters spent a year as a Marshall Scholar at the University of Nottingham working with James J. Turner, . There, he studied physical inorganic chemistry including the photochemical generation and detection of short-lived transient organometallic species by rapid time-resolved infrared spectroscopy.
In fall of 1994, Peters went on to do graduate studies with Christopher "Kit" C. Cummins at the Massachusetts Institute of Technology. At MIT, he studied the activation and functionalization of small molecules using low coordinate tris-amido molybdenum and titanium complexes and prepared the first terminal carbide complex of a transition metal, earning his PhD in 1998.
After graduating, Peters conducted postdoctoral studies as a Miller Fellow at the University of California, Berkeley, under the guidance of T. Don Tilley. In Tilley's group, he concentrated on the synthesis and employment of novel phosphine and silane ligands relevant to late metal Si-C, Si-H, C-H, and C-C bond breaking and forming processes.
Independent career
Peters began as assistant professor in the Division of Chemistry and Chemical Engineering at Caltech in August 1999, was promoted to associate professor in 2004, and to Professor of Chemistry in 2006. In July 2007, he relocated to the MIT Department of Chemistry as the W. M. Keck Professor of Energy. Peters returned to Caltech in January 2010 as Bren Professor of Chemistry and in 2015 he was appointed Director of the Resnick Sustainability Institute.
Peters' laboratory focuses on the synthesis of new inorganic and organometallic species with interesting electronic structure, bonding, and reactivity properties. His laboratory has advanced new concepts for catalysis (including electro- and photocatalysis), with significance to renewable solar fuel technologies, distributed nitrogen fixation for fertilizers and fuels, and chemical transformations fundamental to the synthesis of organic molecules. Peters' research studies are mechanistic in nature and include the characterization of highly reactive species that populate open-shell ground spin states amenable to spectroscopic characterization. He collaborates with many talented scientists, including Gregory Fu on methodology in organic synthesis. In 2021, he was elected to the American Academy of Arts and Sciences, and in 2024 he was elected to the National Academy of Sciences.
References
1971 births
Living people
21st-century American chemists
California Institute of Technology faculty
University of Chicago alumni
Massachusetts Institute of Technology alumni
American inorganic chemists
Recipients of the Presidential Early Career Award for Scientists and Engineers | Jonas C. Peters | [
"Chemistry"
] | 629 | [
"American inorganic chemists",
"Inorganic chemists"
] |
67,685,853 | https://en.wikipedia.org/wiki/Glycerol%20dialkyl%20glycerol%20tetraether | Glycerol dialkyl glycerol tetraether lipids (GDGTs) are a class of membrane lipids synthesized by archaea and some bacteria, making them useful biomarkers for these organisms in the geological record. Their presence, structure, and relative abundances in natural materials can be useful as proxies for temperature, terrestrial organic matter input, and soil pH for past periods in Earth history. Some structural forms of GDGT form the basis for the TEX86 paleothermometer. Isoprenoid GDGTs, now known to be synthesized by many archaeal classes, were first discovered in extremophilic archaea cultures. Branched GDGTs, likely synthesized by acidobacteriota, were first discovered in a natural Dutch peat sample in 2000.
Chemical structure
The chemical nature of GDGTs is succinctly described by its name: they consist of two glycerol molecules connected via two alkyl chains, being held together at four ether linkages. In the living microbe, they are attached to two phosphate head groups that allow them to work as membrane phospholipids. Compared to the typical lipid bilayer in eukaryotes and most bacteria, GDGT-diphosphates differ by having two headgroups, which allow one molecule to do the job of two typical phospholipids (allowing monolayers in water) and resist heat better. They are also connected by ether, instead of ester, bonds.
The two primary structural classes of GDGTs are isoprenoid (isoGDGT) and branched (brGDGT), which refer to differences in the carbon skeleton structures.
Isoprenoid compounds are numbered -0 through -8, with the numeral representing the number of cyclopentane rings present within the carbon skeleton structure. The exception is crenarchaeol, a Nitrososphaerota product with one cyclohexane ring moiety in addition to four cyclopentane rings.
Branched GDGTs have zero, one, or two cyclopentane moieties and are further classified based the positioning of their branches. They are numbered with roman numerals and letters.
The roman numeral describes the total amount of modifications, summing branches and cyclopentane moieties. "I" indicates 4, "II" indicates 5, and "III" indicates 6. The simplest brGDGT is GDGT-I, with four methyls.
A lowercase suffix means that some modifications are cyclopentanes instead of methyl branches. a means one cyclopentane, b means two, and vice versa. For example, GDGT-IIb is a compound with three branches and two cyclopentane moieties (a total of five modifications).
Biological origin
Isoprenoid GDGTs originate as archaeal membrane lipids, whose fatty acids are converted to glycerol via esterification (ether lipid). They were first recognized as being associated with extremophilic archaea, but research in recent decades has discovered the compounds in a wide range of mesophilic environments as well, including soils, lake sediment, and marine deposits. Archaeal phylogenetic classes Nitrososphaerota (formerly Thaumarchaeota), Thermoproteota (formerly Crenarchaeota), "Euryarchaeota", and "Korarchaeota" produce GDGTs.
Branched GDGTs are most commonly detected in peats and soils and are most associated with terrestrial settings. To date, no direct evidence for an unequivocal source organism has been reported, but the structural similarity of acidobacterial lipid to brGDGT alkyl chains strongly suggests that acidobacteriota synthesize brGDGT. The stereochemistry strongly hints at a non-archaeal origin.
GDGT-0
GDGT-0 has zero cyclopentane moieties and is the most ubiquitous isoGDGT synthesized by archaea. Halophilic archaea are the only group of archaea not known to produce GDGT-0. Carbon isotope analyses and association with sites of anaerobic methane oxidation suggest that GDGT-0 is produced via methanotrophs. In microbiology literature not dealing with the geological record, GDGT-0 is sometimes referred to as caldarchaeol.
GDGT-1 – GDGT-4
GDGT-1, GDGT-2, and GDGT-3 have one, two, and three cyclopentane rings respectively within their isoprenoid biphytane carbon structures, respectively. Nitrososphaerota are the largest producers of these groups in marine and lacustrine environments. Methanogens are not thought to be large synthesizers of these molecules, with the exception of Methanopyrus kandleri, which does produce them. These classes are lower in abundance than GDGT-0 and GDGRT-4. They are used in the TEX86 paleothermometer.
GDGT-4 refers to the version with four cyclopentane rings. It is quite abundant (although not easy to differentiate from crenarchaeol on GC/MS, see below). Nitrososphaerota also makes GDGT-4.
Crenarchaeol
Crenarchaeol is mainly attributed to ammonium-oxidizing Nitrososphaerota and has four cyclopentane rings plus one cyclohexane ring, which distinguishes it from GDGT-4 and is unique to the Nitrososphaerota phylum. The evolution of the cyclohexane ring was likely to adjust the density of the membrane packing to more optimally function at the cooler ocean temperatures to which Nitrososphaerota adapted. Due to their structural similarities, crenarchaeol and GDGT-4 have similar GC/MS elution times. They are similar in prevalence to GDGT-0 and therefore are not included in the TEX86 paleothermometer because their abundance overwhelms the less abundant GDGT groups.
A crenarchaeol regioisomer, however, is a part of the TEX86 paleothermometer. This isomer likely differs by having a cis configuration on the cyclopentane ring neighboring the additional cyclohexane ring. It is presumed to be also made by Nitrososphaerota.
GDGT-5 – GDGT-8
GDGTs -5 through -8 are nearly exclusive to extreme high-temperature environments such as hot springs. The larger number of cyclopentane moieties facilitates a more densely packed membrane lipid structure, which better inhibits trans-membrane passage of protons and ions. Doing so increases the molecules' thermal stability, which is necessary to survive at extreme temperatures.
Two proteins responsible for making these GDGTs were identified in Sulfolobus acidocaldarius, a thermoacidophile. grsA is responsible for producing the four cyclopentane rings at the C7 position (also seen in less ring-rich GDGTs), while grsB cyclizes at the unique C3 position. Homologs of the two genes are found throughout Nitrososphaerota.
brGDGT
The building blocks of brGDGT, specifically the long alkyl groups (iso-diabolic acid), are detected in acidobacteria subdivisions 1, 3, 4, and 6. Small amounts of brGDGT-I was detected in Acidobacteriaceae strain A2-4c by full mass spectrum and tentatively in Acidobacteriaceae strain 307 by single-ion monitoring MS; none has been detected in the 44 other strains tested as of 2018. More complex brGDGTs known from nature have not yet been detected in any cell culture.
GDGT-based proxies
TEX86
Because the number of cyclopentane moieties in a GDGT compound is related to the temperature of the growth environment, with increasing numbers of cyclopentane rings resulting in increased thermal stability and allowing for survival at higher temperatures, GDGT distribution and abundance can be employed as paleoclimate proxies. TEX86 is one such paleothermometer which relates distribution and relative abundance of GDGT-1, GDGT-2, GDGT-3, and crenarchaeol isomer to past sea surface temperature (SST) (see TEX86). GDGT-0, GDGT-4, and crenarchaeol are excluded from consideration for this proxy due to their very high abundances relative to isoGDGTs 1–3. The relationship between isoGDGT distribution and temperature is not linear, and some studies have demonstrated its distinctive bias towards unrealistically cold temperatures in the lower latitudes. Current research suggests TEX86 works best in the temperature range 15-34 degrees Celsius. Seasonal variability in archaeal productivity and depth in the water column at which the archaea grow should be considered prior to employing this proxy.
BIT Index
The branched:isoprenoid tetraether (BIT) index relates the relative abundances of brGDGTs in a natural sample to the relative abundance of soil organic matter in that sample. It is calculated by ratioing a sum of bacterially-produced brGDGT abundances over a sum of archaeal isoGDGT abundances and is based on the fundamental idea that brGDGTs are produced most commonly in terrestrial environments (most ubiquitous in soils and peats) while archaeal isoGDGTs (particularly crenarchaeol) are produced in marine environments. While caveats and analytical uncertainties remain an issue, the BIT index is a potentially useful proxy for assessing the amount of fluvially transported soil organic matter compared to marine organic matter.
MBT/CBT index
The methylation of branched tetraethers (MBT) and cyclization of branched tetraethers (CBT) indices relate abundances and distributions of bacterially-produced brGDGTs to relative changes in soil pH and mean annual air temperature. Further research is needed to assess seasonal bias, appropriate calibration protocols, and whether the brGDGT distributions record air or soil temperature.
Measurement techniques
GDGTs are identified via organic geochemical analysis as the polar head groups of the membrane lipids. High-precision liquid chromatography mass spectrometry (HPLC-MS) is the primary means by which GDGTs are analyzed due to this method's tolerance for high temperatures.
References
Biomarkers
Lipids
Ethers | Glycerol dialkyl glycerol tetraether | [
"Chemistry",
"Biology"
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67,685,890 | https://en.wikipedia.org/wiki/Chiral%20switch | A chiral switch is a chiral drug that has already approved as racemate but has been re-developed as a single enantiomer. The term chiral switching was introduced by Agranat and Caner in 1999 to describe the development of single enantiomers from racemate drugs. For example, levofloxacin is a chiral switch of racemic ofloxacin. The essential principle of a chiral switch is that there is a change in the status of chirality. In general, the term chiral switch is preferred over racemic switch because the switch is usually happening from a racemic drug to the corresponding single enantiomer(s). It is important to understand that chiral switches are treated as a selection invention. A selection invention is an invention that selects a group of new members from a previously known class on the basis of superior properties. To express the pharmacological activities of each of the chiral twins of a racemic drug two technical terms have been coined eutomer and distomer. The member of the chiral twin that has greater physiological activity is referred to as the eutomer and the other one with lesser activity is referred to as distomer. The eutomer/distomer ratio is called the eudisimic ratio and reflects the degree of enantioselectivity of the biological activity.
In case of stereoselectivity in action only one of the components in the racemic mixture is truly active (eutomer). The other isomer, the distomer, should be regarded as impurity or isomeric ballast not contributing to the effects aimed at. It is well documented that the pharmacologically inactive isomer (distomer) may contribute to the toxic or adverse effects of the drugs. There is a wide spectrum of possibilities of distomer actions, many of which are confirmed experimentally. Sometimes the single enantiomer version lacks certain side-effects that the racemate exhibits. And where the two enantiomers are sufficiently different in pharmacological effects, it may be possible to get a patent on one or both isomers (for instance, as in the case of propoxyphene). The chiral twins of propoxyphene are separately sold by Eli Lilly and company. Dextropropoxyphene is an analgesic agent (Darvon) and levopropoxyphene an effective antitussive (Novrad). Interestingly the reversed trade names of the drugs, DARVON and NOVRAD, also reflect the chemical mirror-image relationship. A positive consequence of this redesigning approach is that it has given a new life to an old drug, minimizing or avoiding the undesirable side-effect profile. Whether to go in for a chiral switch is normally made on a case-by-case basis. A pragmatic solution could be in favor of a decision-tree approach, incorporating various factors such as pharmacodynamic, pharmacokinetic, toxicological profile of the enantiomers, enantiomer-enantiomer interaction potential, safety, efficacy, risk-benefit ratio, chiral inversion, distomer liability, physicochemical properties, cost of separation and production, quality control criteria, marketing edge, etc.
The concept
The chiral switch concept is illustrated in the diagram. This chiral switch is from (±)-ibuprofen to (S)-(+)-ibuprofen (dexibuprofen). The nonsteroidal anti-inflammatory drug (NSAID) ibuprofen was the first chiral drug of the NSAID class to be switched to the single-enantiomer version in 1994. The switch was done based on the fact that the (S)-ibuprofen, the eutomer, was over 100-fold more potent as an inhibitor of cycloxygenase-1 (COX-1) enzyme than (R)-ibuprofen. Moreover, ibuprofen, when administered as the racemate, the active (R)-enantiomer undergoes partial unidirectional chiral inversion (approximately 60%) to the (S)-enantiomer. Therefore, the use of the single (S)-ibuprofen was expected to give faster onset of action at a lower dosage. Further, while choosing the chiral drug candidate for a chiral switch one should take a look at the chiral inversion tendency of the molecule. For instance, thalidomide, the sedative drug, undergoes bidirectional chiral inversion or racemization in biological systems. In such cases chiral switching efforts will be pointless.
Advantages
There are several possible potential benefits to chiral switching or chiral specific drugs. These include:
An improved (less complex, more selective) pharmacodynamic profile
A higher therapeutic index (improved safety margin)
Less complex pharmacokinetic profile, less complex drug interactions
Less complex relationship between plasma concentration and effect
More rational therapeutic drug monitoring
Expose the patient to less body load and thus reduce metabolic/renal/hepatic drug load
The chiral switching approach has sometimes resulted in failures and disappointments.
Regulatory environment
The roles of regulatory agencies also continue to evolve with respect to the development of chiral switches. An interesting concept brought up in the FDA policy is that of "bridging studies". When a sponsor/innovator seeks to develop a single enantiomer from a racemic drug, the regulatory agencies demand them to conduct bridging studies. Bridging studies are tests (pharmacological and toxicological evaluations) to connect what is known about the already approved racemate and what is unknown about the single enantiomer under study, without going back to square one as for a completely new chemical entity. The intent of the bridging studies is to make sure that the companies are not scarifying some protective effect conferred by the other" isomer when they develop a chiral drug as single enantiomer rather than a racemate. "Bridging" procedure will help to reduce the number of studies required on the "new" enantiopure drug.
Examples
Launched
Chiral switch, a re-engineering approach, has enabled in the remarketing of a number of racemic drugs as chiral specific enantiomer products. Chiral switching strategy is the way most blockbuster drugs have entered the market as enantiopure drugs. A more appropriate term may be unichiral. But the alternate route is de novo (anew) synthesis of chiral specific drugs. The chiral switches may have the same, very similar, therapeutic indications as the original racemic drug. But, there are instances where new indications for the old drug have been reported. The table below gives a brief list of launched chiral switches.
Failed/aborted
The re-evaluation of single enantiomers not without problems. The chiral switches of fluoxetine and fenfluramine are classical examples. The development of (R )-fluoxetine was terminated after patients developed abnormal heart rhythms. The chiral switch of fenfluramine, dexfenfluramine was withdrawn from world marker due to pulmonary hypertension. The table below enumerates couple of chiral switches aborted or withdrawn due stereochemically engineered toxicity.
Evergreening
Evergreening refers to the various strategies whereby owners (innovators/sponsors) of pharmaceutical products use patent laws and minor drug modifications to extend their monopoly privileges on the drug. An enantiomer patent is another form of evergreening based on a chiral switch strategy. Single-enantiomer drugs represent more than 50% of the top-selling 100 drugs worldwide. There are some studies which go to suggest that drug companies employ chiral switching for life-cycle management/patent protection of the parent racemic drug and also as a marketing strategy. Pharmaceutical companies support evergreening practices. Some chiral switches are performed to re-start the patent clock for a medication without reducing side effects or improving efficacy. A high price can then continue to be charged for a medication. Examples include citalopram and escitalopram, and omeprazole and esomeprazole. In both these medications, proposed theoretical benefits were used to market the enantiopure drugs, without any clinical trials being conducted to provide evidence that the racemic drugs improved patient centered outcomes.
Metabolite switches
This idea, drug to metabolite switching, is an extension of the chiral switch concept. The purpose of the switching is to develop an active metabolite which will be devoid of the side-effects and have an improved therapeutic profile compared to the parent chiral drug. Some examples of chiral drug to metabolite switches, (those in the market and others under investigation) include terfenadine to fexofenadine, halofantrine to desbutylhalofantrine, and cisapride to norcisapride. A summary is presented in the table below.
Drug repurposing/chiral-switches
Drug repurposing and chiral switches are part of the secondary pharmaceuticals strategy. The COVID-19 pandemic has increased drug repurposing and this approach suggests combining the two strategies for better results. This combination strategy is not new, but has not been intentional until now. The combination strategy may improve pharmacology, patents, reduce costs, speed up approval times, and increase regulatory exclusivities. The benefits of the combination strategy include superior pharmacology, stronger patents, shorter approval times, and more exclusivity. Patenting this combination strategy is not considered evergreening, product hopping, or me-too. This perspective calls for a comprehensive search for worldwide-approved racemic drugs to be repurposed and combined with chiral switches.
See also
Chiral drugs
Chirality
Enantiopure drug
Chiral inversion
References
External links
Stereochemistry
Enantiopure drugs | Chiral switch | [
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67,686,153 | https://en.wikipedia.org/wiki/Chiral%20drugs | Chemical compounds that come as mirror-image pairs are referred to by chemists as chiral or handed molecules. Each twin is called an enantiomer. Drugs that exhibit handedness are referred to as chiral drugs. Chiral drugs that are equimolar (1:1) mixture of enantiomers are called racemic drugs and these are obviously devoid of optical rotation. The most commonly encountered stereogenic unit, that confers chirality to drug molecules are stereogenic center. Stereogenic center can be due to the presence of tetrahedral tetra coordinate atoms (C,N,P) and pyramidal tricoordinate atoms (N,S). The word chiral describes the three-dimensional architecture of the molecule and does not reveal the stereochemical composition. Hence "chiral drug" does not say whether the drug is racemic (racemic drug), single enantiomer (chiral specific drug) or some other combination of stereoisomers. To resolve this issue Joseph Gal introduced a new term called unichiral. Unichiral indicates that the stereochemical composition of a chiral drug is homogenous consisting of a single enantiomer.
Many medicinal agents important to life are combinations of mirror-image twins. Despite the close resemblance of such twins, the differences in their biological properties can be profound. In other words, the component enantiomers of a racemic chiral drug may differ wildly in their pharmacokinetic, pharmacodynamic profile. The tragedy of thalidomide illustrates the potential for extreme consequences resulting from the administration of a racemate drug that exhibits multiple effects attributable to individual enantiomers. With the advancements in chiral technology and the increased awareness about three-dimensional consequences of drug action and disposition emerged specialized field "chiral pharmacology". Simultaneously the chirality nomenclature system also evolved. A brief overview of chirality history and terminology/descriptors is given below. A detailed chirality timeline is not the focus of this article.
Chirality: history overview
Chirality can be traced back to 1812, when physicist Jean-Baptiste Biot found out about a phenomenon called "optical activity." Louis Pasteur, a famous student of Biot's, made a series of observations that led him to suggest that the optical activity of some substances is caused by their molecular asymmetry, which makes nonsuperimposable mirror-images. In 1848, Pasteur grew two different kinds of crystals from the racemic sodium ammonium salt of tartaric acid. He was the first person to separate enantiomeric crystals by hand. In fact Pasteur laid the foundations of stereochemistry and chirality.
In 1874, Jacobus Henricus van 't Hoff came up with the idea of an asymmetric carbon atom. He said that all optically active carbon compounds have an asymmetric carbon atom. In the same year, Joseph Achille Le Bel only used asymmetry arguments and talked about the asymmetry of the molecules as a whole instead of the asymmetry of each carbon atom. So, Le Bel's idea could be seen as the general theory of stereoisomerism, while van 't Hoff's could be seen as a special case (restricted to tetrahedral carbon).
Soon, scientists started to look into what chiral compounds meant for living things. In 1903, Cushny was the first person to show that enantiomers of a chiral molecule have different biological effects. Lord Kelvin used the word "chiral" for the first time in 1904.
Chirality: terminology/descriptors
This is to give an overview of the evolving chirality nomenclature system commonly employed to distinguish enantiomers of a chiral drug. In the beginning, enantiomers were distinguished based on their ability to rotate the plane of plane-polarized light. The enantiomer that rotates the plane-polarized light to the right is named "dextro-rotatory", abbreviated as "dextro" or "d" and the counterpart as "levo" or "l". A racemic mixture is denoted as "(±)", "rac", or "dl". Now the d/l system of naming based on optical rotation is falling into disuse.
Later, the Fischer convention was introduced to specify the configuration of a stereogenic center and uses the symbols D and L. The use of capital letters is to differentiate from the "d" / "l" notation (optical descriptor) described earlier. In this system, the enantiomers are named with reference to D- and L-glyceraldehyde which is taken as the standard for comparison. The structure of the chiral molecule should be represented in the Fischer projection formula. If the hydroxyl group attached to the highest chiral carbon is on the right-hand side it is referred to as D-series and if on the left-hand side it is called L-series. This nomenclature system has also become obsolete. But D-/L-system of naming is still employed to designate the configuration of amino acids and sugars. In general the D/L system of nomenclature is superseded by the Cahn-Ingold-Prelog (CIP) rule to describe the configuration of a stereogenic/chiral center.
In the CIP or R/S convention, or sequence rule, the configuration, spatial arrangements of ligands/substituents around a chiral center, is labeled as either "R" or "S". This convention is now almost worldwide in use and become a part of the IUPAC (International Union of Pure and Applied Chemistry) rules of nomenclature. In this approach: identify the chiral center, label the four atoms directly attached to the stereogenic center in question, assign priorities according to the sequence rule ( from 1 to 4), rotate the molecule until the lowest priority (number 4) substituent is away from the observer/viewer, draw a curve from number 1 to number 2 to number 3 substituent. If the curve is clockwise, the chiral center is of R-absolute configuration, "R" (Latin, rectus = right). If the curve is counterclockwise, the chiral center is of S-absolute configuration, "S" (Latin, sinister = left). Refer to figure, the Cahn-Ingold-Prelog rule.
An overview of the nomenclature system is presented in the table below.
Racemic drugs
For many years scientists in drug development have been blind to the three-dimensional consequences of stereochemistry, chiefly due to the lack of technology for making enantioselective investigations. Besides the thalidomide tragedy, another event that raised the importance of issues of stereochemistry in drug research and development was the publication of a manuscript in 1984 entitled, "Stereochemistry, a basis of sophisticated nonsense in pharmacokinetics and clinical pharmacology" by Ariëns. This article, and the series of articles that followed, criticized the practice of conducting pharmacokinetic and pharmacodynamic studies on racemic drugs and ignoring the separate contributions of the individual enantiomers. These papers have served to crystallize some of the important issues surrounding racemic drugs and stimulated much discussion in industry, government and academia.
Chiral pharmacology
As a result of these criticisms and the renewed awareness of the three-dimensional effects of drug action fueled by the exponential explosion of chiral technology emerged the new area "stereo-pharmacology". A more specific term is "chiral pharmacology", a phrase popularized by John Caldwell. This field has grown itself into a specialized discipline concerned with the three-dimensional aspects of drug action and disposition. This approach essentially views each version of the chiral twins as separate chemical species. To express the pharmacological activities of each of the chiral twins two technical terms have been coined, eutomer and distomer. The member of the chiral twin that has greater physiological activity is referred to as the eutomer and the other one with lesser activity is referred to as distomer. It is generally understood that this reference is necessarily to a single activity being studied. The eutomer for one effect may well be the distomer when another is studied. The eutomer/distomer ratio is called the eudysmic ratio.
Bio-environment and chiral twins
The behavior of the chiral twins depends mainly on the nature of the environment (achiral/chiral) in which they are present. An achiral environment does not differentiate the molecular twins whereas a chiral environment does distinguish the left-handed version from the right-handed version. Human body, a classic bio-environment, is inherently handed as it is filled with chiral discriminators like amino acids, enzymes, carbohydrates, lipids, nucleic acids, etc. Hence when a racemic therapeutic gets exposed to biological system the component enantiomers will be acted upon stereoselectively. For drugs, chiral discrimination can take place either in the pharmacokinetic or pharmacodynamic phase.
Chiral discrimination
Easson and Stedman (1933) advanced a drug-receptor interaction model to account for the differential pharmacodynamic activity between enantiomeric pairs. In this model the more active enantiomer (the eutomer) take part in a minimum of three simultaneous intermolecular interactions with the receptor surface (good fit), Figure. A., where as the less active enantiomer (distomer) interacts at two sites only (bad fit), Figure B. [Refer image for Figure: Easson-Stedman model]. Thus the "fit" of the individual enantiomers to the receptor site differs, as does the energy of interaction. This is a simplistic model but used to explain the biological discrimination between enantiomeric pairs.
In reality the drug-receptor interaction is not that simple, but this view of such complex phenomenon has provided major insights into the mechanism of action of drugs.
Pharmacodynamic considerations
Racemic drugs are not drug combinations in the accepted sense of two or more co-formulated therapeutic agents, but combinations of isomeric substances whose pharmacological activity may reside predominantly in one specific enantiomeric form. In case of stereoselectivity in action only one of the components in the racemic mixture is truly active. The other isomer, the distomer, should be regarded as impurity or isomeric ballast, a term coined by Ariëns, not contributing to the effects aimed at. In contrast to the pharmacokinetic properties of an enantiomeric pair, differences in pharmacodynamic activity tend to be more obvious. There is a wide spectrum of possibilities of distomer actions, many of which are confirmed experimentally. Selected examples of the distomer actions (viz. equipotent, less active, inactive, antagonistic, chiral inversion) are presented in the table below.
Drug toxicity
Since there is a frequent large pharmacokinetic and pharmacodynamic differences between enantiomers of a chiral drug it is not surprising that enantiomers may result in stereoselective toxicity. They can reside in the pharmacologically active enantiomer (eutomer) or in the inactive one (distomer). The toxicologic differences between enantiomers of have also been demonstrated. The following are examples of some of the chiral drugs where their toxic/undesirable side-effects dwell almost in the distomer. This would seem to be a clear cut case of going for a chiral switch.
Penicillamine
Penicillamine is a chiral drug with one chiral center and exists as a pair of enantiomers. (S)-penicillamine is the eutomer with the desired antiarthritic activity while the (R)-penicillamine is extremely toxic.
Ketamine
Ketamine is a widely used anaesthetic agent. It is a chiral molecule that is administered as a racemate. Studies show that (S)-(+)-ketamine is the active anaesthetic and the undesired side-effects (hallucination and agitation) reside in the distomer, (R)-(-)-ketamine.
Dopa
The initial use of racemic dopa for the treatment of Parkinson's disease resulted in a number of adverse effects viz. nausea, vomiting, anorexia, involuntary movements and granulocytopenia. The use of L-dopa [the (S)-enantiomer] resulted in reducing the required dose, and adverse effects. The granulocytopenia was not observed with the single enantiomer.
Ethambutol
The antitubercular agent Ethambutol contains two constitutionally symmetrical stereogenic centers in its structure and exists in three stereoisomeric forms. An enantiomeric pair (S,S)- and (R,R)-ethambutol, along with the achiral stereoisomer called meso-form, it holds a diastereomeric relationship with the optically active stereoisomers. The activity of the drug resides in the (S,S)-enantiomer which is 500 and 12 fold more potent than the (R,R)-ethambutol and the meso-form. The drug had initially been introduced for clinical use as the racemate and was changed to the (S,S)-enantiomer, as a result of optic neuritis leading to blindness. Toxicity is related to both dose and duration of treatment. All the three stereoisomers were almost equipotent with respect to side effects. Hence the use of S,S)-enantiomer greatly enhanced the risk/benefit ratio.
Thalidomide
Thalidomide is a classical example highlighting the alleged role of chirality in drug toxicity. Thalidomide was a racemic therapeutic and prescribed to pregnant women to control nausea and vomiting. The drug was withdrawn from world market when it became evident that the use in pregnancy causes phocomelia (clinical conditions where babies are born with deformed hand and limbs). Later in late 1970s studies indicated that the (R)- enantiomer is an effective sedative, the (S)-enantiomer harbors teratogenic effect and causes fetal abnormalities. Later studies established that under biological conditions the (R)-thalidomide, good partner, undergoes an in vivo metabolic inversion to the (S)-thalidomide, evil partner and vice versa. It is a bidirectional chiral inversion. Hence the argument that the thalidomide tragedy could have been avoided by using a single enantiomer is ambiguous and pointless.
The salient features are presented in the table below.
Unichiral drugs
Unichiral indicates configurationally homogeneous substance (i.e. made up of chiral molecules of one and the same configuration). Other commonly used synonyms are enantiopure drugs and enantiomerically pure drugs. Monochiral drugs has also been suggested as another synonym. Professor Eliel, Wilen, and Gal expressed their deep concern over the misuse of the term "homochiral" in articles to denote enantiomerically pure drugs, which is incorrect. Homochiral means objects or molecules of the same handedness. Hence should be used only for comparison of two or more objects of like "chirality". For instance, left hands of different individuals, or say R-naproxen and R-ibuprofen.
Globally drug companies and regulatory agencies have an inclination towards the development of unichiral drugs as a consequence of the increased understanding of the differing biological properties of individual enantiomers of a racemic therapeutics. Most of these unichiral drugs are the consequence of chiral switch approach. The table below list selected unichiral drugs used in drug therapy.
A company may go in for developing a racemic drug against an enantiomer by providing adequate reasoning. The rationale why a company might pursue developing racemic drugs could include expensive separation of enantiomers, eutomer racemizes in solution (e.g. oxazepam), activities of the enantiomeric pair are different but supplementary, distomer is inactive, but separation is exorbitant. Insignificant/low toxicity of the distomer, high therapeutic index, mutually beneficial, pharmacological activities of both the enantiomers, and if the development of an enantiomer takes huge amount of time for a drug of emergency need e.g., cancer, AIDS, etc.
Chiral purity
Chiral purity is a measure of the purity of a chiral drug. Other synonyms employed include enantiomeric excess, enantiomer purity, enantiomeric purity, and optical purity. Optical purity is an obsolete term since today most of the chiral purity measurements are done using chromatographic techniques (not based on optical principles). Enantiomeric excess tells the extent (in %) to which the chiral substance contains one enantiomer over the other. For a racemic drug the enantiomeric excess will be 0%. There are number of chiral analysis tools such as polarimetry, NMR spectroscopy with the use of chiral shift reagents, chiral GC (gas chromatography), chiral HPLC (high performance liquid chromatography), chiral TLC (thin-layer chromatography) and other chiral chromatographic techniques, that are employed to evaluate chiral purity. Assessing the purity of a unichiral drug or enantiopure drug is of great importance from a drug safety and efficacy perspective.
See also
Chirality (chemistry)
Chiral switch
Chiral analysis
Enantiopure drug
Chiral inversion
Racemate
Stereochemistry
Chirality timeline
References
External links
Chirality
Enantiopure drugs
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] |
67,686,502 | https://en.wikipedia.org/wiki/INSACOG | INSACOG (Indian SARS-CoV-2 Consortium on Genomics or Indian SARS-CoV-2 Genetics Consortium) is the forum set up under the Ministry of Health and Family Welfare by the Government of India on 30 December 2020, to study and monitor genome sequencing and virus variation of circulating strains of COVID-19 in India. Initially it was tasked to study the virus variant Lineage B.1.1.7 earlier found in United Kingdom in December 2020.
INSACOG works as a consortium of 38 national laboratories for genome sequencing located in different parts of India. All these 10 laboratories are required to share 5% of positive samples to INSACOG for further research and studies. A National Centre for Disease Control (NCDC) nodal unit maintain a database of all samples of the new variants. Two national genomic sequencing database centers are appointed 1) National Institute of Biomedical Genomics and 2) CSIR Institute of Genomics and Integrative Biology. In its early research INSACOG identified virus variant Lineage B.1.617 referred to as a double mutation variant.
See also
GISAID
References
COVID-19 pandemic in India
Scientific organisations based in India
Genomics
Bioinformatics organizations
Council of Scientific and Industrial Research
Biological research institutes
Ministry of Health and Family Welfare | INSACOG | [
"Biology"
] | 266 | [
"Bioinformatics",
"Bioinformatics organizations"
] |
67,686,875 | https://en.wikipedia.org/wiki/Baroclinic%20instabilities%20in%20the%20ocean | A baroclinic instability is a fluid dynamical instability of fundamental importance in the atmosphere and ocean. It can lead to the formation of transient mesoscale eddies, with a horizontal scale of 10-100 km. In contrast, flows on the largest scale in the ocean are described as ocean currents, the largest scale eddies are mostly created by shearing of two ocean currents and static mesoscale eddies are formed by the flow around an obstacle (as seen in the animation on eddy (fluid dynamics). Mesoscale eddies are circular currents with swirling motion and account for approximately 90% of the ocean's total kinetic energy. Therefore, they are key in mixing and transport of for example heat, salt and nutrients.
In a baroclinic medium, the density depends on both the temperature and pressure. The effect of the temperature on the density allows lines of equal density (isopycnals) and lines of equal pressure (isobars) to intersect. This is in contrast to a barotropic fluid, in which the density is only a function of pressure. For this barotropic case, isobars and isopycnals are parallel. The intersecting of isobars and isopycnals in a baroclinic medium may cause baroclinic instabilities to occur by the process of sloping convection. The sizes of baroclinic instabilities and therefore also the eddies they create scale with the Rossby radius of deformation, which strongly varies with latitude for the ocean.
Instability and eddy generation
In a baroclinic fluid, the thermal-wind balance holds, which is a combination of the geostrophic balance and the hydrostatic balance. This implies that isopycnals can slope with respect to the isobars. Furthermore, this also results in changing horizontal velocities with height as a result of horizontal temperature and therefore density gradients.
Under the thermal-wind balance, geostrophic balance and hydrostatic balance, a flow is in equilibrium. However, this is not the equilibrium of least energy. A reduction in slope of the isopycnals would lower the center of gravity and therefore also the potential energy. It would also reduce the pressure gradient, leading to an increase in the kinetic energy. However, under the thermal-wind balance, a decrease in slope of the isopycnals cannot occur spontaneously. It requires a change of potential vorticity. Under certain conditions, slight perturbations of the equilibrium under the thermal-wind balance may increase, leading to larger perturbations from the initial state and thus the growth of an instability.
It is often considered that baroclinic instability is the mechanism which extracts potential energy stored in horizontal density gradients and uses this "eddy potential energy" to drive eddies.
Sloping convection
These baroclinic instabilities may be initiated by the process of 'sloping convection' or 'slanted thermal convection'. To understand this, consider a fluid in steady state and under the thermal-wind balance. Initially, a fluid parcel is at location A. The fluid parcel is slightly perturbed to location B, while still retaining its original density. Therefore, the fluid parcel is now in a location with a lower density than itself and the parcel will just sink down to its original position; the fluid parcel is now stable. However, when a parcel displaced to location C, it is surrounded by fluid with a higher density than the parcel itself. Due to its relatively low density with respect to its surroundings, the parcel will float up even further. Now a small perturbation grows into a larger one, which implies a baroclinic instability.
A criterion for an instability to occur can be defined. As stated before, in a baroclinic fluid, the thermal-wind balance holds, which implies the following two relations:
and ,
where is the density and , and are the spatial coordinates in the horizontal (latitudinal and longitudinal) and vertical direction, respectively. and represent the horizontal (zonal and meridional) components of the velocity vector in the - and -direction, respectively. Now thus and are the two horizontal density gradients. is the gravitational acceleration at the surface of the Earth and the Coriolis parameter.
Therefore a horizontal density gradient in the -direction leads to a gradient in horizontal flow velocity over depth .
The slope of the displacement is defined as
,
where and are the horizontal and vertical velocities of the perturbation, respectively.
An instability now occurs when the slope of the displacement is smaller than the slope of the isopycnals. The isopycnals can be mathematically described as . Now this results in an instability when:
From now on, only a two layer system with and the slopes of the top and bottom layer, respectively, is considered to simplify the problem. This is now similar to the classic Philips model. From the thermal-wind balance it now follows that
where is the reduced gravity and the Coriolis-parameter at the equator according to the beta-plane approximation.
Performing a scale analysis on the slope of the perturbation allows to assign physical quantities to this mathematical problem. This now results in
,
where is the scale height, the horizontal length scale, and is the Rossby-parameter.
From this it can be stated that an instability occurs when
or ,
where is the reduced gravity and is the velocity difference between the lower and upper layer. This criterion can be used to identify whether a small perturbation will grow into a larger one and thus whether an instability is expected to occur. From this it follows that you need some kind of shear to obtain an instability, it is easier to get an instability for long waves (perturbations) with large , and the and therefore the beta-effect is stabilizing.
Furthermore, for the baroclinic Rossby radius of deformation it holds that . Now the instability criteria simplify to
or .
From this analysis it also follows that baroclinic instabilities are important for small Rossby numbers, where .
Observations of Baroclinic instabilities and eddies
Recently, many observations on mesoscale eddies in the ocean have been made using sea surface height data from altimeters. It has been shown that regions with the highest growth rate of baroclinic instabilities indeed match the regions which are rich in eddies. Furthermore, also the trajectories of both cyclonic and anticyclonic eddies can be studied. From this it follows that there are approximately the same number of cyclonic and anticyclonic eddies observed and therefore it is concluded that the generation of these two types is very similar. However, when considering longer lived eddies, they found that anticyclonic eddies clearly dominate. This implies that cyclonic eddies are less stable and therefore decay more rapidly. In addition, there are no eddies present above shallows in the ocean due to topographic steering as a result of the Taylor–Proudman theorem. Lastly, extremely long lived eddies with lifetimes over 1.5 to 2 years are only found in gyres, most likely because the background flow is small here.
Four different types of Baroclinic instabilities can be distinguished:
Eady type
Charney surface type
Charney bottom type
Phillips type
These four types are based on classical models (the classic Eady Model, the Charney model, and the Phillips model, respectively), but can also be distinguished from observations. Overall, from the observed baroclinic instabilities 47% is the Charney surface type, 33% the Phillips type, 13% the Eady type and only 7% the Charney bottom type. These different types of Baroclinic instabilities all lead to different types of eddies. Important here is ψ, which is the absolute value of the complex eigenfunction of the stream function of the horizontal velocity. It represents the vertical structure of the Baroclinic instability and ranges from 0, which implies a very low chance of an instability of this type and thus also eddy to form, to 1, which means a high chance.
The Eady type has a maximum ψ of one at the top and bottom, and a minimum around 0.5 halfway the total depth. For this type of model, an eddy thus occurs at both the surface and bottom of the ocean. It is therefore also called the surface- and bottom-intensified type and found mainly at high latitudes. The Charney surface type is surface-intensified and has a maximum ψ at the surface, whereas the Charney bottom type only shows baroclinic instabilities at the bottom. For the Charney bottom type ψ is also at the surface and increases to one over increasing depth. The Charney surface type is found in the subtropics, whereas the Charney bottom type is present at high latitudes. Lastly, for the Phillips type, ψ is zero at the surface, strongly increases to one just below the surface, and then slowly decreases again to zero for increasing depths. The location of these Phillips type instabilities agree with the occurrence of subsurface eddies, again supporting the idea that the Baroclinic instabilities lead to the formation of eddies. They are mostly found in the tropics and the eastern return flow of the subtropical gyres.
It was found that the type of Baroclinic instability present also depends on the mean background flow. An Eady type is preferred for a strong eastward mean flow in the upper ocean, and a weak westward flow in the deeper ocean. For the Charney bottom type this is similar, but now the westward flow in the deeper ocean is found to be stronger. The Charney surface and Phillips types exist for weaker background flows, also explaining why these are dominant in the ocean gyres.
References
Fluid dynamics
Physical oceanography | Baroclinic instabilities in the ocean | [
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"Chemical engineering",
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67,687,783 | https://en.wikipedia.org/wiki/Topographic%20steering | In fluid mechanics, topographic steering is the effect of potential vorticity conservation on the motion of a fluid parcel. This means that the fluid parcels will not only react to physical obstacles in their path, but also to changes in topography or latitude. The two types of 'fluids' where topographic steering is mainly observed in daily life are air (air can be considered a compressible fluid in fluid mechanics) and water in respectively the atmosphere and the oceans. Examples of topographic steering can be found in, among other things, paths of low pressure systems and oceanic currents.
In 1869, Kelvin published his circulation theorem, which states that a barotropic, ideal fluid with conservative body forces conserves the circulation around a closed loop. To generalise this, Bjerknes published his own circulation theorem in 1898. Bjerknes extended the concept to inviscid, geostrophic and baroclinic fluids, resulting in addition of terms in the equation.
Mathematical description
Circulation
The exact mathematical description of the different potential vorticities can all be obtained from the circulation theorem of Bjerkness, which is stated as
.
Here is the circulation, the line integral of the velocity along a closed contour. Also, is the material derivative, is the density, is the pressure, is the angular velocity of the frame of reference and is the area projection of the closed contour onto the equatorial plane. This means the bigger the angle between the contour and the equatorial plane, the smaller this projection becomes.
The formula states that the change of the circulation along a fluid's path is affected by the variation of density in pressure coordinates and by the change in equatorial projection of the contour. Kelvin assumed both a barotropic fluid and a constant projection. Under these assumptions the right hand side of the equation is zero and Kelvin's theorem is found.
Shallow water
When considering a relatively thin layer of fluid of constant density, with on the bottom a topography and on top a free surface, the shallow water approximation can be used. Using this approximation, Rossby showed in 1939, by integrating the shallow water equations over the depth of the fluid, that
.(1)
Here is the relative vorticity, is the Coriolis parameter and is the height of the water layer. The quantity inside the material derivative was later called the shallow water potential vorticity.
Layered atmosphere
When considering an atmosphere with multiple layers of constant potential temperature, the quasi-2D shallow water equations on a beta plane can be used. In 1940, Rossby used this to show that
.(2)
Here is the relative vorticity on an isentropic surface, is the Coriolis parameter and is a quantity measuring the weight of unit cross-section of an individual air column in the layer. This last quantity can also be seen as a measure of the vortex depth. The potential vorticity defined here is also called the Rossby potential vorticity.
Continuous atmosphere
When the approximation of the discrete layers is relaxed and the fluid becomes continuous, another potential vorticity can be defined which is conserved. It was shown by Ertel in 1942 that
.(3)
Here is the absolute vorticity, is the gradient in potential temperature and the density. This potential vorticity is also called the Ertel potential vorticity.
To get to this result, first recall the circulation theorem from Kelvin
.
If the coordinate system is transformed to the one of the local tangent plane coordinates and we use potential temperature as the vertical coordinate, the equation can be slightly rewritten to
.
Where now is the local circulation in the frame of reference, is Coriolis parameter and is the area on an isentropic surface over which the circulation .
Because the local circulation can be approximated as a product between the area and the relative vorticity on the isentropic surface, the circulation equation yields
.
When a fluid parcel is between two isentropic layers and the pressure difference between these layers increases, the fluid parcel is 'stretched'. This is because it wants to conserve the potential temperature at each side of the parcel. To conserve the mass, this horizontally thins the fluid parcel while it is vertically stretched. So the area of the isentropic surface, , is a function of how quickly the lines of equal potential temperature change with pressure:
.
In the end this yields
,
which is exactly the result found by Ertel, written in a slightly different way. Note that when assuming a layered atmosphere, the gradient in the potential temperature becomes an absolute difference and the result from Kelvin for a layered atmosphere can be found. Also note that when the fluid is incompressible, the layer depth becomes a measure for the change in potential temperature. Then the result for shallow water potential vorticity can be extracted again.
Effect
The different definitions of potential vorticity conservation, resulting from different approximations, can be used to explain phenomena observed here on earth. Fluid parcels will move along lines of constant potential vorticity.
Oceans
Because the scale of large flows in the oceans is much larger than the depth of the ocean, the shallow water approximation and thus (1) can often be used. On top of that, the changes in relative vorticity are very small with respect to the changes in the Coriolis parameter. The direct result of that is that for a fluid parcel a change in ocean floor depth will have to be compensated by a change in latitude. In both hemispheres this means that a rising ocean floor, so a decrease in water depth, results in a deflection equatorwards.
This phenomenon can explain different currents found on earth. One of them is the specific path the water takes in the Antarctic Circumpolar Current. This path is not a straight line, but curves according to the bathymetry.
Another one is the water flowing through the Luzon Strait. Researchers Metzger and Hurlburt showed that the existence of three small shoals can explain the deflection of the current away from the strait instead of flowing through the strait.
Atmosphere
In the atmosphere, topographic steering can also be observed. In most cases, the simple modeled layer of the atmosphere and thus (2) can explain the phenomena. When an isentropic layer flows zonally from west to east over a mountain, the topographic steering can create a wave-like pattern on the lee-side and eventually form an alternating pattern of ridges and troughs.
Upon approach of the mountain, the layer depth will increase slightly. This is because the incline of the isentropic surfaces is less steep at the top of the layer than at the bottom. When the layer depth increases, the change in potential vorticity is countered by an increase in relative vorticity as well as the Coriolis parameter. The vortex will begin to move away from the equator and begin to rotate cyclonically.
During the crossing of the mountain, the effect is reversed due to the shrinking of the layer depth. The vortex will rotate anti-cyclonically and move towards the equator. As the vortex leaves the mountain, the resulting latitude is closer to the equator than before. This means vortices will have a cyclonic rotation on the lee-side of the mountain and be turning northwards. The Coriolis parameter and relative vorticity increase and decrease in antiphase. This results in an alternation of cyclonic and anti-cyclonic flows after the mountain. The change in the Coriolis parameter and relative vorticity work against each other, creating a wave-like phenomenon.
When looking at zonal flow from east to west, this effect is not occurring. This is because the change in the Coriolis parameter and the change in relative vorticity work in the same direction. The flow will return to zonal again some time after crossing the mountain.
The effect described is often credited as the source of the tendency of cyclogenesis on lee-sides of mountains. One example of this are the so called Colorado lows, troughs originating from air passing over the Rocky Mountains.
See also
Potential vorticity
Circulation (physics)
Kelvin's circulation theorem
Shallow water equations
References
Oceanography
Atmospheric dynamics
Fluid mechanics | Topographic steering | [
"Physics",
"Chemistry",
"Engineering",
"Environmental_science"
] | 1,672 | [
"Hydrology",
"Applied and interdisciplinary physics",
"Atmospheric dynamics",
"Oceanography",
"Civil engineering",
"Fluid mechanics",
"Fluid dynamics"
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67,688,679 | https://en.wikipedia.org/wiki/57%20Pegasi | 57 Pegasi is a variable binary star system in the northern constellation of Pegasus (constellation). It has the variable star designation GZ Pegasi, while 57 Pegasi is the Flamsteed designation. The system is faintly visible to the naked eye as a point of light with an apparent visual magnitude that fluctuates around 5.105. It is located at a distance of approximately 780 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +14 km/s.
The variability of this star was discovered by J. Stebbins and C. M. Huffer in 1930. It was classified as a long-period variable of type Lb in 1974. However, based on a constant period and the shape of the light curve, it was later reclassified as a semiregular variable of type SRa in 1978. It varies in brightness from magnitude 4.95 down to 5.23 with a period of 92.66 days. The spectrum of 57 Peg displays blended features that indicate this is a binary system consisting of an aging red giant star on the asymptotic giant branch with a stellar classification of M4IIIa, and a fainter but hotter A-type main-sequence companion of class A3V. This spectroscopic binary system has poorly constrained orbital elements with an estimated orbital period of 100–500 years.
The red giant primary has been designated as an S-type star that shows enriched levels of s-process elements in its spectrum. However, it does not display significant lines of radioactive technetium-99 in its spectrum, indicating that the s-process elements must have been acquired from a mass transfer event from a formerly asymptotic giant branch companion that had passed through multiple dredge-up events. This would suggest it has a white dwarf as a tertiary companion, but this is incompatible with the data findings. Instead, it might have been misclassified as an S-type star.
There is a magnitude 10.06 visual companion at an angular separation of along a position angle of 198° from the primary, as of 2015. Designated component B, this star was first reported by F. G. W. Struve in 1827.
References
M-type giants
A-type main-sequence stars
Asymptotic-giant-branch stars
Semiregular variable stars
S-type stars
Spectroscopic binaries
Pegasus (constellation)
BD+07 4981
Pegasi, 57
218634
114347
8815
Pegasi, GZ | 57 Pegasi | [
"Astronomy"
] | 520 | [
"Pegasus (constellation)",
"Constellations"
] |
67,689,493 | https://en.wikipedia.org/wiki/Low-latitude%20western%20boundary%20currents | Low-latitude western boundary currents (LLWBC) are western boundary currents located between the subtropical gyres, within 20° of the equator. They are important for closing the tropical circulation driven by the equatorial zonal flow, and facilitate inter-ocean transport between the subtropical gyres. They occur in regions of negative (positive) wind stress curl in the southern (northern) hemisphere, and originate at the western bifurcation point of the South or North Equatorial Current. They are typically equatorward (cyclonic) as opposed to sub-tropical western boundary currents, which tend to be poleward (anticyclonic). Some well-known examples include the Mindanao Current (MC) and the East African Coastal Current (EACC).
LLWBCs transport a lot of mass, and bring cooler, saltier, and denser water from the subtropics to the warm, less salty, and less dense waters of the tropics. They are subject to changes in intensity and direction on seasonal and multi-annual timescales because of the annual variance in latitude of the equatorial currents and El Niño-Southern Oscillation.
LLWBCs in the Atlantic
The LLWBC in the Atlantic is the North Brazil Current (NBC). While it does initially transport quite salty water, its salinity changes considerably along its course due to the massive influx of fresh water from the Amazon delta. This influx makes it of vital importance for the transport of colder, relatively fresher water to the Northern Atlantic. Most of the water below 12 degrees that flows through the Caribbean is transported from the South Atlantic by this current.
The NBC develops as the equatorward branch of the South Equatorial Current (SEC), and transports 23 - 26 Sv of seawater along the north Brazil coast towards Venezuela at a speed of approximately 1 m/s. During its journey north it feeds both the North Equatorial Undercurrent (NEUC) and the North Equatorial Countercurrent (NECC) in a series of retroflections between 6°N and 8°N.
Near Barbados, it feeds the Yucatan (or Caribbean) Current (YC), which has a mean transport of 30 Sv.
LLWBCs in the Indian Ocean
The EACC and the Somali Current (SC) are the principal LLWBCs in the Indian Ocean. The East Indian Coastal Current (EIC) is sometimes considered a LLWBC.
Comparatively fresh water is transported from the maritime continent and the Pacific via the Indonesian Throughflow (ITF) to the western Indian Ocean by the SEC. Near Madagascar, the lower branch of the SEC splits into the North (or North-eastern) and South (or South-Eastern) Madagascar Currents (SMC). The North Madagascar Current (NMC) then splits into the Mozambique Current (MZC) and the EACC. Depending on the season, the EACC (with a peak transport of around 19 Sv at 8°N) will either feed into the northward SC, or converge with the southward SC to form the NECC where it is transported back across the Indian Ocean. Retroflections from the EACC form the South Gyre and Great Whirl.
Both the EIC in the Bay of Bengal and the SC change direction depending on the monsoon. In the case of the EIC, when there is a north-easterly monsoon it is directed towards the south-west, and when there is a south-westerly monsoon it is directed towards the north-east. The SC follows a similar pattern.
LLWBCs in the Pacific
The system of LLWBCs in the Pacific is of significant interest because of the irregular topography, the fact that the currents involved modulate the amount of heat and mass entering the Western Pacific Warm Pool, and because they help to air the relatively deep tropical thermocline. Additionally, the convergence of the two LLWBCs marks the source of the ITF, the only major ocean-to-ocean point of leakage on the planet.
The southern of the two LLWBC systems begins just north of the Great Barrier Reef, where a lower limb of the South Equatorial Current splits into the East Australian Current and the Gulf of Papua Current (GPC). The GPC travels around the southern tip of New Guinea and becomes the New Guinea Coastal Undercurrent (NGCU), which is found at depths of 200 to 400 m and is most intense during the SW monsoon, with transport varying between 20 and 29 Sv. The NGCU travels through the Solomon Sea and along the northern New Guinea coast via the Vitiaz Strait, Solomon Strait, or St Georges' Strait. In the Celebes Sea, the NGCU meets the MC. Water masses are recycled through massive eddies and feed the ITF (15 Sv) and the NECC.
Near Luzon, saltier subtropical water in the North Equatorial Current (NEC) bifurcates into the MC and the Kuroshio Current (KC). The MC, with a transport of 15 - 35 Sv, follows the Philippine archipelago to the south before meeting the southern hemisphere waters.
Beneath the MC there is a Mindanao Undercurrent (MUC), which had been thought to be directed poleward, and located precisely underneath the MC. In fact, what actually happens beneath the thermocline is a little bit more complicated. At a large scale (>400 km), there is indeed a more or less constant northward MUC; however, on smaller scales, there is an alternating pattern of poleward and equatorward flows driven by eastward zonal jets were found at 7°N, 10°N, 13°N, and 18°N.
The New Guinea Coastal Current (NGCC) also changes direction with the monsoon.
Mixing in LLWBCs
In contrast to sub-tropical western boundary currents, where isopycnal mixing is elevated due to shear stress—which increases as you approach a western boundary—as well as internal wave-breaking, the picture regarding mixing in LLWBC is less clear. Recent experiments have shown that in the Mindanao Eddy (ME) there is relatively less mixing than found in a sub-tropical western boundary current. This may be indicative of LLWBCs in general; however, previous research had suggested the opposite.
Climate Change
As is the case for other western boundary currents, the amount of mass transported by LLWBCs will change in the future. This will be driven by basin-scale changes in the wind field or deep circulation across decades. Transport along the MC and NBC may weaken by 2.3 to 5.6 Sv and -1.7 to -4.7 Sv respectively, while transport along the GPC and the NGCU may intensify by 0.6 to 2.8 Sv and 1.9 to 4.9 Sv respectively. Models also indicate that while currents in the southern Indian Ocean may weaken significantly, the EACC does not appear to be likely to change significantly in strength.
Such climatic-induced changes in circulation are now being recognised as an additional stressor on marine ecosystems. For strengthening LLWBCs such as the GPC, given that they oppose climate change velocities (which are poleward), dispersal of larvae to more thermally-appropriate locations may be more difficult. For weakening LLWBCs such as the MC, such relocation may be made less difficult.
References
Boundary layer meteorology
Wind
Ocean currents | Low-latitude western boundary currents | [
"Chemistry"
] | 1,516 | [
"Ocean currents",
"Fluid dynamics"
] |
67,690,210 | https://en.wikipedia.org/wiki/Cyazofamid | Cyazofamid is a fungicide that is highly-specific in controlling oomycete plant pathogens such as Phytophthora infestans, the organism which causes late blight in potato. Its mode of action is thought to involve binding to the Qi center of Coenzyme Q – cytochrome c reductase.
Cyazofamid is most often sold under the brand name Ranman.
Synthesis
Processes to manufacture cyazofamid were disclosed in patents from Ishihara Sangyo Kaisha, Ltd. An acetophenone derivative was first treated with aqueous glyoxal and hydroxylamine to form an oxime-substituted imidazole ring system. This intermediate was treated with thionyl chloride and disulfur dichloride to convert the oxime to a cyano group and chlorinate the imidazole in the position next to the phenyl ring. Finally, treatment with dimethylsulfamoyl chloride gave cyazofamid, with the desired regiochemistry. This placed the sulfamoyl group on the nitrogen adjacent to the phenyl ring rather than the chlorine atom. The structure of the fungicide has been confirmed by X-ray crystallography.
References
Further reading
AGRIS id JP2004007452. CiNii NAID 130004444938. ISSN-L 0385-1559.
External links
Fungicides
Sulfonamides
Imidazole antifungals
Nitriles
Chloroarenes | Cyazofamid | [
"Chemistry",
"Biology"
] | 324 | [
"Fungicides",
"Nitriles",
"Biocides",
"Functional groups"
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67,691,927 | https://en.wikipedia.org/wiki/Metal-ligand%20cooperativity | Metal-ligand cooperativity (MLC) is a mode of reactivity in which a metal and ligand of a complex are both involved in the bond breaking or bond formation of a substrate during the course of a reaction. This ligand is an actor ligand rather than a spectator, and the reaction is generally only deemed to contain MLC if the actor ligand is doing more than leaving to provide an open coordination site. MLC is also referred to as "metal-ligand bifunctional catalysis." Note that MLC is not to be confused with cooperative binding.
The earliest reported metal-ligand cooperativity was from the Fujiwara group in the 1950s, in which they reported formation of stilbene from styrene and arenes using a palladium chloride catalyst. Shvo's catalyst was developed for one of the earliest uses of ketone hydrogenation by an outer-sphere mechanism. Noyori has developed many chiral catalysts for asymmetric hydrogenation. Transfer hydrogenation, one of the most commonly used applications of MLC, is employed broadly in industry for large scale Noyori-type reductions.
Modes of Metal-Ligand Cooperativity
There are a variety of modes in which this cooperativity has been demonstrated. Four primary modes are generally accepted under MLC: the ligand can (1) act with Lewis acidity, (2) act with Lewis basicity, (3) play a role in aromatization and dearomatization, or (4) be redox non-innocent.
The ligand can act as a Lewis acid and accept electrons from an incoming substrate as it binds to the metal, as in employed in dehydrogenation catalysis. Conversely, the ligand can be Lewis basic and bind the substrate; this Lewis basicity is most frequently seen in hydrogenation catalysis.
The aromatization and dearomatization of a ligand can serve to facilitate a reaction. As shown in the figure, a ligand can be dearomatized by a base and thus activated toward cleaving a C-H or H-H bond and be subsequently rearomatized during substrate bond cleavage. NHC ligands and other pincer ligands are frequently employed in this mode of MLC. In some reports, with bidentate ligands, ligand dearomatization is not observed when the complex is treated with base but rather a complex with a formal metal-carbon bond is observed (that then acts as a Lewis basic ligand).
The ligand can also be redox non-innocent to facilitate reactions that the metal would otherwise be unable to activate. The ligand can act as an electron reservoir, which is enabled when ligands contain frontier orbitals of suitable energy to participate in the redox event themselves, and can accept or donate electrons during the course of the reaction, allowing the metal to modulate its oxidation state. This allows metals which normally only participate in one electron regimes to be used in two electron regimes with a redox non-innocent ligand to store electrons during the reaction. Dithiolate ligands have been used extensively as one electron redox active ligands in metal complexes. For example, dithiolates have been demonstrated to allow for the selective and reversible reduction of ethylene in the presence H2, CO, and H2S. This has applications in the purification of ethylene gas streams, in which ethylene can be reduced electrochemically by a dithiolate, selectively removed from the impurities in the stream, and then reversibly desaturated.
Electrochemical metal-ligand cooperativity in redox reactions allows for ease of tuning the potential of the ligands to avoid off-target reactivity.
There are a number of other ligand modes of reactivity which are sometimes classified under MLC. This includes reactions in which the ligand accepts or loses a proton, though not directly from or to the substrate. Ligands can also be used to form stabilizing H-bonds, which can be applied in molecular recognition catalysis. Ligands can also be designed to be photoresponsive, with applications in molecular switches. Ligands may also be considered to be involved in MLC while acting only in the second coordination sphere (not directly bound to the metal) but acting as a proton shuttle. Frustrated Lewis pairs, in which an ion pair of the type [R3B-H]−[H-Ar3]+ transfer a hydride and proton are also sometimes classified under MLC.
Mechanism of Hydrogenations with Metal-Ligand Cooperativity
MLC is most frequently used in hydrogenations, with many applications in asymmetric catalysis and in process scale production of chemicals. In a hydrogenation, there is a transfer of a hydride and a hydrogen to a substrate. Typical substrates include aldehydes, ketones, and imines. As this is a common use for MLC, it is instructive in understanding the mechanism of metal-ligand cooperativity. MLC occurs through an outer sphere mechanism. An outer sphere mechanism does not necessitate that the metal undergo oxidative addition or reductive elimination. Thus, H2 is not added across the metal, but rather across the metal and a ligand; alternatively, the metal complexes are preformed to contain a hydride ligand as well as a ligand with a hydrogen alpha to the metal. Thus, the hydride and hydrogen are adjacent to one another, facilitating the transfer to the substrate; this transfer occurs without the substrate ever binding to the metal itself. Though amine is by far the most used ligand in cooperativity, other actor ligands include alkoxides and thiols.
In contrast, in an inner sphere mechanism, the substrate will be inserted into the metal and reaction with hydrogen will then afford the hydrogenated product. This mechanism does not employ MLC. The differentiation between an outer sphere mechanism relying on MLC and an inner sphere mechanism is exemplified by cobalt hydrogenation with an amine pincer ligand. In the outer sphere mechanism, the hydrogen on the pincer ligand is added into the ketone along with a hydride ligand on the metal. It is worth noting that there is debate over the concertedness of the transition state of this outer sphere hydrogenation step, and different reactions and catalysts may be either concerted or stepwise, and in some scenarios there may be multiple pathways at play. In comparison to the ketone hydrogenation, an olefin undergoes an inner sphere mechanism under the same reaction conditions, in which the olefin inserts directly into the metal. These mechanistic differences between the ketone and olefin are corroborated by the observation that the ketone hydrogenation will not occur with an N-Me pincer ligand, and the olefin hydrogenation will proceed with the N-Me ligand, suggesting the ketone requires the presence of the N-H bond while the olefin does not.
Common Ligands
MLC is most broadly used with M-NH systems. Nyori and others have developed an extensive library of diamine ligands which serve in hydrogenation reactions, following the general outer sphere mechanism illustrated above. These systems are typically ruthenium complexes containing phosphine ligands as the spectator ligands. Many of these diphosphine ligands, such as BINAP, contain arene rings and impart chirality from atropisomerism; the rigidity of the phosphene ligands can impart chirality on prochiral substrates with high fidelity, allowing for asymmetric hydrogenation. Reactivity of metal complexes used in MLC can be tuned greatly by the use of different diphosphine spectator ligands.
M-OH metal ligand systems have application in MLC. Shvo's catalyst was one of the earliest complexes developed for ketone and aldehyde reductions to alcohols. The ruthenium complex (1), upon heating, dissociates into a 18 electron complex (2) and a 16 electron complex (3), the former of which is catalytically active. The hydroxy group on the cyclopentadienyl is the actor ligand, donating a hydrogen in an outer sphere mechanism. Bäckvall has developed use for Shvo's catalyst in the dynamic kinetic resolution of alcohols with lipases.
Bergman and coworkers developed a sulfur ligand for activation of H-H as well as Si-H bonds. A titanium sulfide complex binds H2 across the titanium and sulfur, yielding a hydride and thiol ligand. A similar mode of reactivity is seen with H-Si bonds, in which the sulfide forms a bond with the silicon, and the titanium accepts the hydride. The use of sulfur ligands in MHC has continued to expand since Bergman's early work in the field. Iridium and rhenium complexes with bridging sulfides have been demonstrated to heterolytically cleave H2.
Metal boron complexes have also been demonstrated to be useful in activating H2. These ligands are less developed for the purpose of MLC, and commonly suffer from off target alkyl and aryl migration from the boron ligand to other ligands or substrates which disrupts the catalytic cycle
References
Hydrogenation | Metal-ligand cooperativity | [
"Chemistry"
] | 1,906 | [
"Hydrogenation"
] |
67,692,128 | https://en.wikipedia.org/wiki/Thermohaline%20staircase | Thermohaline staircases are patterns that form in oceans and other bodies of salt water, characterised by step-like structures observed in vertical temperature and salinity profiles; the patterns are formed and maintained by double diffusion of heat and salt. The ocean phenomenon consists of well-mixed layers of ocean water stacked on top of each other. The well-mixed layers are separated by high-gradient interfaces, which can be several meters thick. The total thickness of staircases ranges typically from tens to hundreds of meters.
Two types of staircases are distinguished. Salt-fingering staircases can be found at locations where relatively warm, salty water overlies relatively colder, fresher water. Here, large-scale temperature and salinity both increase upward, making the mixing process of salt fingering possible. Locations where you can find these type of staircases are for example beneath the Mediterranean outflow, in the Tyrrhenian Sea, and northeast Caribbean. Diffusive staircases can be found at locations where both temperature and salinity increase downward, for example in the Arctic Ocean and in the Weddell Sea. An important feature of thermohaline staircases is their extreme stability in space and time. They can persist several years or more and can extend for hundreds of kilometers. The interest in thermohaline staircases is partly due to the fact that the staircases represent mixing hot spots in the main thermocline.
Extensive definition and detection
To determine the presence of thermohaline staircases, the following steps can be taken according to the algorithm designed by Van der Boog.
The first step of the algorithm is to identify the mixed layers by locating weak vertical density gradients in conservative temperature and absolute salinity. To do so, the threshold gradient method is used with a threshold of , with the pressure and the reference pressure. The vertical conservative temperature, absolute salinity, and potential density gradients are all below the threshold value by meeting these three conditions:
with the thermal expansion coefficient, the haline contraction coefficient, the reference density, the conservative temperature, and the salinity.
The second step is to define the interface, which is the part of the water column in the middle of two mixed layers. It is required that the conservative temperature, absolute salinity, and potential density variations in the interface should be larger than the variations within each mixed layer to ensure a stepped structure. Therefore the following conditions should be met:
where subscript 1 corresponds to the mixed layer above the interface and subscript 2 corresponds to the mixed layer below the interface.
The third step is to limit the interface height . The interface height should be smaller than the height of the mixed layers directly above and below the interface . This condition has to be met in order to ensure that the interface is relatively thin compared to the mixed layers surrounding it. Furthermore, the algorithm removes all interfaces with conservative temperature or absolute salinity inversions to make sure that it only detects step-like structures that are associated with the presence of thermohaline staircases.
The fourth step is to determine the double-diffusive regime (salt-fingering or diffusive) of each interface. When both conservative temperature and absolute salinity of the mixed layers above and below the interface increase downward, the interface belongs to the diffusive regime. When both conservative temperature and absolute salinity of the mixed layers above and below the interface both increase upward, the interface is classified as the salt-fingering regime.
Finally, only vertical sequences of at least two interfaces in the same double-diffusive regime are selected, where the interfaces should be separated from each other by only one mixed layer. This way, most thermohaline intrusions are removed, as these are characterised by alternating mixed layers in the diffusive and salt-finger regimes. Furthermore, the algorithm removes salt-fingering interfaces and diffusive-convective interfaces outside their favourable Turner angle , a parameter used to describe the local stability of an inviscid water column. Interfaces with salt-fingering characteristics should correspond to Turner angles of and interfaces with diffusive-convective characteristics should correspond to Turner angles of .
Staircase origin
The origin of thermohaline staircases relies on double diffusive convection, and specifically on the fact that heated water diffuses more readily than salty water. However, there is still much debate on which specific mechanism of layering plays a role. Six possible mechanisms are described below.
Collective instability mechanism
This mechanism, involving collective instability, relies on the idea that after a period of active internal wave motion, layers appear. This hypothesis was motivated by laboratory experiments in which staircases formed from the initially uniform temperature and salinity gradients. Growing waves might overturn and generate the stepped structure of thermohaline staircases.
Thermohaline intrusion mechanism
This hypothesis states that staircases represent the final stage in the evolution of thermohaline intrusions. Intrusions can evolve either to a state consisting of alternating salt-finger and diffusive interfaces separated by convecting layers, which is common at high density ratio , or to a series of salt-finger interfaces when the density ratio is low . This proposition relies on the presence of lateral property gradients to drive interleaving. This mechanism, where thermohaline intrusions are transformed into staircases, are likely to exist in strong temperature-salinity fronts.
Metastable equilibria mechanism
A different theory states that staircases represent distinct metastable equilibria. It is suggested that finite amplitude perturbations to the gradient state force the system into a layered regime where it can remain for long periods of time. Large initial perturbations to the gradient state make the transition to the staircase more likely and accelerate the process. Once the staircase is created, the system becomes resilient to further structural changes.
Applied flux mechanism
The applied flux mechanism was mainly tested in laboratory experiments, and is most likely at work in cases when layering is caused by geothermal heating. When a stable salinity gradient is heated from below, top-heavy convection will take place in the lower part of the water column. The well-mixed convecting layer is bounded from above by a thin high-gradient interface. By a combination of molecular diffusion and entrainment across the interface, heat is transferred upward from the convecting layer. The molecular transfer of heat exceeds that of salt, resulting in a supply of buoyancy to the region immediately above the interface. This leads to the formation of a second convecting layer. The process can repeat itself over and over, which results in a sequence of mixed layers separated by sharp interfaces, a thermohaline staircase.
Negative density diffusion
In salt-fingering staircases, vertical temperature and salinity fluxes are downgradient, while the vertical density flux is upgradient. This is explained by the fact that the potential energy released in transporting salt downward must exceed that expended in transporting heat upward, resulting in a net downward transport of mass. This negative diffusion sharpens the fluctuations and therefore suggests a means for generating and maintaining staircases.
Instability of flux-gradient laws
This mechanism is based on negative density diffusion as well. However, instead of combining temperature and salinity into a single density term, it treats both density components individually. In a publication by Radko, it is shown that formation of steps in numerical models is caused by the parametric variation of the flux ratio as a function of the density ratio , leading to an instability of equilibrium with uniform stratification. These unstable perturbations continuously grow in time until well-defined layers are formed.
Observations
Two types of staircases exist: salt-fingering staircases, where both temperature and salinity of the mixed layers decrease with pressure (and therefore with depth); and diffusive staircases, where both temperature and salinity of the mixed layers increase with pressure (so with depth).
Salt-fingering staircases
Most observations of salt-fingering staircases have come from three locations: the western Tropical Atlantic, the Tyrrhenian Sea, and the Mediterranean outflow. In these regions the density ratio has a very low value, which appears to be a condition for sufficient staircase formation. No staircases have been reported for values below 2. For values below 1.7, the step-like structures in vertical temperature and salinity profiles becomes apparent. Moreover, the spatial pattern of staircases is very sensitive to . With decreasing , the height of steps sharply increases and the staircases become more pronounced. The importance of the density ratio for the formation is a sign that staircases are a product of double diffusive convection.
In the Tyrrhenian Sea, thermohaline staircases due to salt fingers are observed. The step-like shape is visible in the vertical temperature and salinity profiles. Staircases in the Tyrrhenian Sea show a very high stability in space and time. The weak deep circulation in this area might be an explanation for this stability.
Diffusive staircases
Diffusive staircases are found at higher latitudes. In the Arctic Ocean, warm and salty water from the Atlantic enters the Arctic basin and subducts beneath the colder and fresher waters of the upper Arctic. In some regions, also Pacific waters sit below the mixed layer and above the Atlantic layer. A thermocline is found at the top of the Atlantic Water layer. In that region, temperature and salinity increases with depth and step-like patterns are observed in vertical temperature and salinity profiles. These staircases mediate the heat transport from the warm water of Atlantic origin to the Arctic halocline and therefore serve as an important process in determining the heat flux from the Atlantic Water upward to the sea ice. Staircases in the Arctic are characterised by much smaller steps than in salt-fingering staircases.
On a much smaller scale, diffusive staircases have also been observed in low- and mid-latitudes. For example, Lake Kivu and Lake Nyos show characteristic staircase patterns. In these salt-water lakes, geothermal springs supply heat at the bottom resulting in the diffusive background stratification.
See also
Salt fingering
Double diffusive convection
Oceans portal
References
Patterns
Physical oceanography | Thermohaline staircase | [
"Physics"
] | 2,142 | [
"Applied and interdisciplinary physics",
"Physical oceanography"
] |
67,693,073 | https://en.wikipedia.org/wiki/NGC%203412 | NGC 3412 is a barred lenticular galaxy located in the constellation Leo. It was discovered on April 8, 1784, by the astronomer William Herschel.
References
External links
Leo (constellation)
3412
Barred lenticular galaxies
032508 | NGC 3412 | [
"Astronomy"
] | 50 | [
"Leo (constellation)",
"Constellations"
] |
67,695,754 | https://en.wikipedia.org/wiki/Effects%20of%20climate%20change%20on%20the%20water%20cycle | The effects of climate change on the water cycle are profound and have been described as an intensification or a strengthening of the water cycle (also called hydrologic cycle). This effect has been observed since at least 1980. One example is when heavy rain events become even stronger. The effects of climate change on the water cycle have important negative effects on the availability of freshwater resources, as well as other water reservoirs such as oceans, ice sheets, the atmosphere and soil moisture. The water cycle is essential to life on Earth and plays a large role in the global climate system and ocean circulation. The warming of our planet is expected to be accompanied by changes in the water cycle for various reasons. For example, a warmer atmosphere can contain more water vapor which has effects on evaporation and rainfall.
The underlying cause of the intensifying water cycle is the increased amount of greenhouse gases in the atmosphere, which lead to a warmer atmosphere through the greenhouse effect. Fundamental laws of physics explain how the saturation vapor pressure in the atmosphere increases by 7% when temperature rises by 1 °C. This relationship is known as the Clausius-Clapeyron equation.
The strength of the water cycle and its changes over time are of considerable interest, especially as the climate changes. The hydrological cycle is a system whereby the evaporation of moisture in one place leads to precipitation (rain or snow) in another place. For example, evaporation always exceeds precipitation over the oceans. This allows moisture to be transported by the atmosphere from the oceans onto land where precipitation exceeds evapotranspiration. The runoff from the land flows into streams and rivers and discharges into the ocean, which completes the global cycle. The water cycle is a key part of Earth's energy cycle through the evaporative cooling at the surface which provides latent heat to the atmosphere, as atmospheric systems play a primary role in moving heat upward.
The availability of water plays a major role in determining where the extra heat goes. It can go either into evaporation or into air temperature increases. If water is available (like over the oceans and the tropics), extra heat goes mostly into evaporation. If water is not available (like over dry areas on land), the extra heat goes into raising air temperature. Also, the water holding capacity of the atmosphere increases proportionally with temperature increase. For these reasons, the temperature increases dominate in the Arctic (polar amplification) and on land but not over the oceans and the tropics.
Several inherent characteristics have the potential to cause sudden (abrupt) changes in the water cycle. However, the likelihood that such changes will occur during the 21st century is currently regarded as low.
Overview
Heating of the Earth leads to more energy cycling within its climate system, causing changes to the global water cycle. These include first and foremost an increased water vapor pressure in the atmosphere. This causes changes in precipitation patterns with regards to frequency and intensity, as well as changes in groundwater and soil moisture. Taken together, these changes are often referred to as an "intensification and acceleration" of the water cycle. Key processes that will also be affected are droughts and floods, tropical cyclones, glacier retreat, snow cover, ice jam floods and extreme weather events.
The increasing amount of greenhouse gases in the atmosphere leads to extra heating of the lower atmosphere, also known as the troposphere. The saturation vapor pressure of air rises along with its temperature, which means that warmer air can contain more water vapor. Transfers of heat to land, ocean and ice surfaces additionally promote more evaporation. The greater amount of water in the troposphere then increases the chances for more intense rainfall events.
This relation between temperature and saturation vapor pressure is described in the Clausius–Clapeyron equation, which states that saturation pressure will increase by 7% when temperature rises by 1 °C. This is visible in measurements of the tropospheric water vapor, which are provided by satellites, radiosondes and surface stations. The IPCC AR5 concludes that tropospheric water vapor has increased by 3.5% over the last 40 years, which is consistent with the observed temperature increase of 0.5 °C.
The human influence on the water cycle can be observed by analyzing the ocean's surface salinity and the "precipitation minus evaporation (P–E)" patterns over the ocean. Both are elevated. Research published in 2012 based on surface ocean salinity over the period 1950 to 2000 confirm this projection of an intensified global water cycle with salty areas becoming more saline and fresher areas becoming more fresh over the period. IPCC indicates there is high confidence that heavy precipitation events associated with both tropical and extratropical cyclones, and atmospheric moisture transport and heavy precipitation events will intensify.
Intermittency in precipitation
Climate models do not simulate the water cycle very well. One reason is that precipitation is a difficult quantity to deal with because it is inherently intermittent. Often, only the average amount is considered. People tend to use the term "precipitation" as if it was the same as "precipitation amount". What actually matters when describing changes to Earth's precipitation patterns is more than just the total amount: it is also about the intensity (how hard it rains or snows), frequency (how often), duration (how long), and type (whether rain or snow). Scientists have researched the characteristics of precipitation and found that it is the frequency and intensity that matter for extremes, and those are difficult to calculate in climate models.
Observations and predictions
Since the middle of the 20th century, human-caused climate change has included observable changes in the global water cycle. The IPCC Sixth Assessment Report in 2021 predicted that these changes will continue to grow significantly at the global and regional level.
The report also found that: Precipitation over land has increased since 1950, and the rate of increase has become faster since the 1980s and in higher latitudes. Water vapour in the atmosphere (in particular the troposphere) has increased since at least the 1980s. It is expected that over the course of the 21st century, the annual global precipitation over land will increase due to a higher global surface temperature.
A warming climate makes extremely wet and very dry occurrences more severe. There can also be changes in atmospheric circulation patterns. This will affect the regions and frequency for these extremes to occur. In most parts of the world and under all climate change scenarios, water cycle variability and accompanying extremes are anticipated to rise more quickly than the changes of average values.
In 2024 the World Meteorological Organization published a report saying that climate change had severely destabilized water cycle during the year 2023, causing both stronger rainfall and stronger drought. The world’s rivers had their driest year in at least 30 years and many of the world’s major river basins were drying up like the basins of Mississippi, Amazon, Ganges, Brahmaputra and Mekong. For 3 years in a row, more than 50% of global catchment areas had lower than normal river discharges. Glaciers lost more than 600 gigatons of water – the biggest water loss in the last 50 years. It was the second year in a row in which all glaciated regions had ice loss.
Changes to regional weather patterns
Regional weather patterns across the globe are also changing due to tropical ocean warming. The Indo-Pacific warm pool has been warming rapidly and expanding during the recent decades, largely in response to increased carbon emissions from fossil fuel burning. The warm pool expanded to almost double its size, from an area of 22 million km2 during 1900–1980, to an area of 40 million km2 during 1981–2018. This expansion of the warm pool has altered global rainfall patterns, by changing the life cycle of the Madden Julian Oscillation (MJO), which is the most dominant mode of weather fluctuation originating in the tropics.
Potential for abrupt change
Several characteristics of the water cycle have the potential to cause sudden (abrupt) changes of the water cycle. The definition for "abrupt change" is: a regional to global scale change in the climate system that happens more quickly than it has in the past, indicating that the climate response is not linear. There may be "rapid transitions between wet and dry states" as a result of non-linear interactions between the ocean, atmosphere, and land surface.
For example, a collapse of the Atlantic meridional overturning circulation (AMOC), if it did occur, could have large regional impacts on the water cycle. The initiation or termination of solar radiation modification could also result in abrupt changes in the water cycle.There could also be abrupt water cycle responses to changes in the land surface: Amazon deforestation and drying, greening of the Sahara and the Sahel, amplification of drought by dust are all processes which could contribute.
The scientific understanding of the likelihood of such abrupt changes to the water cycle is not yet clear. Sudden changes in the water cycle due to human activity are a possibility that cannot be ruled out, with current scientific knowledge. However, the likelihood that such changes will occur during the 21st century is currently regarded as low.
Measurement and modelling techniques
Changes in ocean salinity
Due to global warming and increased glacier melt, thermohaline circulation patterns may be altered by increasing amounts of freshwater released into oceans and, therefore, changing ocean salinity. Thermohaline circulation is responsible for bringing up cold, nutrient-rich water from the depths of the ocean, a process known as upwelling.
Seawater consists of fresh water and salt, and the concentration of salt in seawater is called salinity. Salt does not evaporate, thus the precipitation and evaporation of freshwater influences salinity strongly. Changes in the water cycle are therefore strongly visible in surface salinity measurements, which has already been known since the 1930s.
The advantage of using surface salinity is that it is well documented in the last 50 years, for example with in-situ measurement systems as ARGO. Another advantage is that oceanic salinity is stable on very long time scales, which makes small changes due to anthropogenic forcing easier to track. The oceanic salinity is not homogeneously distributed over the globe, there are regional differences that show a clear pattern. The tropic regions are relatively fresh, since these regions are dominated by rainfall. The subtropics are more saline, since these are dominated by evaporation, these regions are also known as the 'desert latitudes'. The latitudes close to the polar regions are then again less saline, with the lowest salinity values found in these regions. This is because there is a low amount of evaporation in this region, and a high amount of fresh meltwater entering the Arctic Ocean.
The long-term observation records show a clear trend: the global salinity patterns are amplifying in this period. This means that the high saline regions have become more saline, and regions of low salinity have become less saline. The regions of high salinity are dominated by evaporation, and the increase in salinity shows that evaporation is increasing even more. The same goes for regions of low salinity that are become less saline, which indicates that precipitation is intensifying only more. This spatial pattern is similar to the spatial pattern of evaporation minus precipitation. The amplification of the salinity patterns is therefore indirect evidence for an intensifying water cycle.
To further investigate the relation between ocean salinity and the water cycle, models play a large role in current research. General Circulation Models (GCMs) and more recently Atmosphere-Ocean General Circulation Models (AOGCMs) simulate the global circulations and the effects of changes such as an intensifying water cycle. The outcome of multiple studies based on such models support the relationship between surface salinity changes and the amplifying precipitation minus evaporation patterns.
A metric to capture the difference in salinity between high and low salinity regions in the top 2000 meters of the ocean is captured in the SC2000 metric. The observed increase of this metric is 5.2% (±0.6%) from 1960 to 2017. But this trend is accelerating, as it increased 1.9% (±0.6%) from 1960 to 1990, and 3.3% (±0.4%) from 1991 to 2017. Amplification of the pattern is weaker below the surface. This is because ocean warming increases near-surface stratification, subsurface layer is still in equilibrium with the colder climate. This causes the surface amplification to be stronger than older models predicted.
An instrument carried by the SAC-D satellite Aquarius, launched in June 2011, measured global sea surface salinity.
Between 1994 and 2006, satellite observations showed an 18% increase in the flow of freshwater into the world's oceans, partly from melting ice sheets, especially Greenland and partly from increased precipitation driven by an increase in global ocean evaporation.
Salinity evidence for changes in the water cycle
Essential processes of the water cycle are precipitation and evaporation. The local amount of precipitation minus evaporation (often noted as P-E) shows the local influence of the water cycle. Changes in the magnitude of P-E are often used to show changes in the water cycle. But robust conclusions about changes in the amount of precipitation and evaporation are complex. About 85% of the earth's evaporation and 78% of the precipitation happens over the ocean surface, where measurements are difficult. Precipitation on the one hand, only has long term accurate observation records over land surfaces where the amount of rainfall can be measured locally (called in-situ). Evaporation on the other hand, has no long time accurate observation records at all. This prohibits confident conclusions about changes since the industrial revolution. The AR5 (Fifth Assessment Report) of the IPCC creates an overview of the available literature on a topic, and labels the topic then on scientific understanding. They assign only low confidence to precipitation changes before 1951, and medium confidence after 1951, because of the scarcity of data. These changes are attributed to human influence, but only with medium confidence as well. There have been limited changes in regional monsoon precipitation observed over the 20th century because increases caused by global warming have been neutralized by cooling effects of anthropogenic aerosols. Different regional climate models project changes in monsoon precipitation whereby more regions are projected with increases than those with decreases.
Convection-permitting models to predict weather extremes
The representation of convection in climate models has so far restricted the ability of scientists to accurately simulate African weather extremes, limiting climate change predictions. Convection-permitting models (CPMs) are able to better simulate the diurnal cycle of tropical convection, the vertical cloud structure and the coupling between moist convection and convergence and soil moisture-convection feedbacks in the Sahel. The benefits of CPMs have also been demonstrated in other regions, including a more realistic representation of the precipitation structure and extremes. A convection-permitting (4.5 km grid-spacing) model over an Africa-wide domain shows future increases in dry spell length during the wet season over western and central Africa. The scientists concludes that, with the more accurate representation of convection, projected changes in both wet and dry extremes over Africa may be more severe. In other words: "both ends of Africa's weather extremes will get more severe".
Impacts on water management aspects
The human-caused changes to the water cycle will increase hydrologic variability and therefore have a profound impact on the water sector and investment decisions. They will affect water availability (water resources), water supply, water demand, water security and water allocation at regional, basin, and local levels.
Water security
Water scarcity
Droughts
Desertification
Floods
Groundwater quantity and quality
See also
Effects of climate change on oceans
Ocean temperature
References
Effects of climate change
Forms of water
Hydrology | Effects of climate change on the water cycle | [
"Physics",
"Chemistry",
"Engineering",
"Environmental_science"
] | 3,260 | [
"Hydrology",
"Phases of matter",
"Forms of water",
"Environmental engineering",
"Matter"
] |
67,696,055 | https://en.wikipedia.org/wiki/.sexy | .sexy is a generic top-level domain owned by Uniregistry. Delegated on 14 November 2013, .sexy was the subject of controversy due to opposition from the government of Saudi Arabia and privacy concerns regarding registering domains.
History
.sexy, along with .tattoo, was one of the first two gTLDs launched by Uniregistry on 14 November 2013. Its sunrise period, during which pre-existing trademark holders may register URLs prior to general availability to prevent domain squatting, lasted from 11 December 2013 to 9 February 2014, and it entered general availability on 25 February 2014. .sexy was one of the first hundred gTLDs to be delegated. Prior to its release, .sexy was one of many announced gTLDs, variously reported as 31 and over 160, that the Communication and Information Technology Commission of the government of Saudi Arabia objected to; other TLDs found objectionable included .gay, .casino, .sucks, .wine, and .bible.
On the first day of .sexy's general availability, around 2,000 domain names were registered, which commentators described as a "disappointing" low showing. The domain had a comparable number of first-day registrations as unpopular domains from Uniregistry's competitor Donuts such as .gallery and .estate. .sexy's launch was hampered by a lack of support from and availability at major domain name registrars such as GoDaddy, based in privacy concerns around Uniregistry's demands that registrants inform Uniregistry of their real names and identities to purchase domains. A number of pre-orders of .sexy domains were also stymied by domain name collision, the phenomenon where a private (intranet) domain name system queries a public one, and by names that had been pre-ordered being reserved by Uniregistry.
In 2015, a survey by ICANN concluded networks in Iran were systematically blocking .sexy domains. In 2017, Uniregistry CEO Frank Schilling increased the price of .sexy and a number of other domains due to low uptake. Schilling stated that the costs of running a TLD demanded that low-use TLDs, such as .sexy, be sold at higher price points in order to turn a profit.
Usage
According to Schilling, .sexy domains are intended "for fun, for fashion, for recreation, as a novelty, [and] for risqué content". .sexy has also been associated with cybersquatting, with cybersquatters purchasing .sexy domains for major companies who rejected having their trademarks associated with adult industries; such misuse was predicted prior to the domain's release, with commentators describing them as potentially costing companies "serious money". Explicit content is prohibited on the home pages of websites with .sexy domains, although sites are permitted to have a landing page with a warning button that needs to be clicked through to access such content.
, there are 10,203 registered .sexy domains, making up 0.03% of all domains. NameCheap holds the majority of the .sexy market share with 65.8%, although 14% of .sexy domains are registered by registries outside the top ten. The domain's lack of popularity was described by domain expert Kevin Murphy as a failure of Schilling's own practices:
See also
Internet pornography
References
Top-level domains
Generic top-level domains
2013 introductions
Sexuality and computing | .sexy | [
"Technology"
] | 704 | [
"Computing and society",
"Sexuality and computing"
] |
67,696,150 | https://en.wikipedia.org/wiki/Lagrangian%20ocean%20analysis | Lagrangian ocean analysis is a way of analysing ocean dynamics by computing the trajectories of virtual fluid particles, following the Lagrangian perspective of fluid flow, from a specified velocity field. Often, the Eulerian velocity field used as an input for Lagrangian ocean analysis has been computed using an ocean general circulation model (OGCM). Lagrangian techniques can be employed on a range of scales, from modelling the dispersal of biological matter within the Great Barrier Reef to global scales. Lagrangian ocean analysis has numerous applications, from modelling the diffusion of tracers, through the dispersal of aircraft debris and plastics, to determining the biological connectivity of ocean regions.
Techniques
Lagrangian ocean analysis makes use of the relation between the Lagrangian and Eulerian specifications of the flow field, namely
where defines the trajectory of a particle (fluid parcel), labelled , as a function of the time , and the partial derivative is taken for a given fluid parcel . In this context, is used to identify a given virtual particle - physically it corresponds to the position through which that particle passed at time . In words, this equation expresses that the velocity of a fluid parcel at the position along its trajectory that it reaches at time can also be interpreted as the velocity at that point in the Eulerian coordinate system. Using this relation, the Eulerian velocity field can be integrated in time to trace a trajectory,
where is a dummy integration variable. In this equation, is continuous in space – for the integration of trajectories in a Lagrangian ocean model, the velocity field must be evaluable at any point in space. Spatial interpolation is used so that the velocity field can be evaluated at points inside the grid cells outputted by OGCMs.
Time Integration
In some cases, the time integration is performed using explicit time-stepping methods. Lagrangian ocean analysis codes may make use of, for instance, an Euler method, or a higher order method, such as Runge-Kutta 4 or Runge-Kutta 4-5. If the timestep of the integration method is shorter than the time resolution of the Eulerian velocity field used as an input, then the velocity field must be interpolated in the temporal domain, so that there is a velocity value to be integrated for each time.
To ensure volume conservation in integrating the trajectories, symplectic methods, can be used. These methods are generally implicit in nature, requiring extra computation when compared to explicit methods.
Alternatively, if each component of the flow velocity within a spatial grid is assumed to vary linearly along its axis, trajectories can be analytically calculated. If the velocity field is steady-state, then trajectories can be treated as streamlines, and considered together in bundles known as stream tubes, which bound fluid flow in different parts of the spatial domain. If the velocity field provided as the starting point of the Lagrangian analysis is a divergence-free flow, the volume of fluid moving through a stream tube is conserved throughout the stream tube. To show this mathematically, the starting point is the condition that the divergence of the velocity field is zero,
Integrating this over the volume of a stream tube, the divergence theorem can be used to show that
where is the normal to the surface of the stream tube, denotes the entire volume of the stream tube and its surface. If the streamlines and pathlines (trajectories) are equivalent, as is the case for steady-state (non time-evolving) flows, then the walls of the stream tube do not contribute to the integral, as the flow cannot cross them. Thus, only the ends, and will contribute to the integral, so
Physically, this equation expresses that the fluid flux passing through the two ends of the streamtube are equal, demonstrating the volume conservation. The equation also shows that the area of each end of the stream tube is inversely proportional to the speed of the normal flow through it. These features of the analytical method of calculating trajectories lend themselves to Lagrangian analyses primarily concerned with the advective (as opposed to diffusive) component of the flow.
There exists a caveat to this approach: given that the velocity fields considered can be time-evolving, the equivalence between stream tubes and material pathways may not hold. Lagrangian ocean models can address this formalism by considering the flow field to be a piecewise function in the temporal domain, where each sub-function is a steady-state velocity field. A Boussinesq model, in which flow is incompressible and thus non-divergent, can be used to generate the velocity field used as an input for the Lagrangian analysis code to ensure volume is conserved when using this method.
Incorporating Diffusion
For a Lagrangian ocean analysis code to include the effects of molecular diffusion, or other small-scale mixing which may be modelled as a diffusive process, stochastic terms must be added to the trajectory computations. Stochastic terms may be added in accordance with a stochastic differential equation (SDE) derived from the tracer diffusion equation in the form of the Fokker-Planck equation. This method requires that a diffusion tensor be provided.
Rather than using an SDE derived with a diffusion tensor, Lagrangian ocean models may instead find an SDE based on how well the resulting diffusivity statistics fit either observations or models built with a finer resolution. This method involves the use of a Markov chain; the order of the Markov chain used is another point where different Lagrangian analysis codes differ.
Online and Offline Analysis
Lagrangian ocean analysis codes can be characterised as online or offline. Online codes work in tandem with the Eulerian model that outputs the velocity field: each time the Eulerian model updates, the trajectories are timestepped using the new velocity information. The Lagrangian analysis packages available with some OGCMs are examples of online Lagrangian ocean analysis codes. Offline codes calculate trajectories using stored velocity fields outputted by Eulerian models at a prior stage. As a result of this, offline models may be used to calculate trajectories forwards or backwards through time; the latter may be helpful in determining the origins of water masses. As of 2018, there are no examples of online models that use the tracer equation to compute diffusive effects.
Applications
One strength of Lagrangian ocean models is that they can be less computationally expensive than calculating the advection diffusion of a tracer concentration within the Eulerian paradigm: for each timestep, the Lagrangian code needs only evaluate the position of each virtual particle, as opposed to the Eulerian model which must explicitly calculate the tracer concentration in every grid cell. In the case of offline models, trajectories may be advected backwards in time which can be useful in finding sources of the material being tracked.
Lagrangian ocean analysis has found use in tracking water masses, for instance tracking the source and pathways of the Subantarctic Mode Water, as well as how its temperature and salinity evolve along its path. Another application of Lagrangian modelling techniques is in simulating the dispersal of biological matter in different ocean regions to gauge their biological connectivity.
Lagrangian ocean analysis has also been used to model the dispersal of materials originating in human activities, for example in tracking the spread of oil following the 2010 Deepwater Horizon oil spill and in attempts to model dispersal of Debris from flight MH370 in the Indian Ocean since 2014. Furthermore, Lagrangian ocean analysis has played a role in the tracking of the transport of plastics across the global ocean, for instance helping researchers estimate the fraction of plastic debris that ends up at the coast.
Examples
While small scale Lagrangian analysis codes have been written for many individual research projects, there exists a smaller number of community codes that can implement Lagrangian ocean models on a global scale. The differences between 10 such community codes are illustrated in the venn diagram, where they are grouped in terms of whether they are offline, whether they include a stochastic term to model diffusion or small-scale turbulent mixing, and whether they compute trajectories analytically. All of the codes in the diagram that lie outside of the analytic trajectories circle employ explicit integration methods to compute the trajectories. Ariane, for example, is a code that runs offline, calculates trajectories with the analytic streamtube method and does not model diffusive effects. By contrast, Parcels computes particle trajectories through explicit time-stepping and can include stochastic terms if the user desires; it is also offline. A caveat to this is that Parcels' integration framework is customisable, and could be reprogrammed to instead use the analytical method to calculate trajectories.
See also
Lagrangian and Eulerian specification of the flow field
Lagrangian analysis
Lagrangian particle tracking
References
Physical oceanography | Lagrangian ocean analysis | [
"Physics"
] | 1,898 | [
"Applied and interdisciplinary physics",
"Physical oceanography"
] |
67,696,353 | https://en.wikipedia.org/wiki/Remote%20sensing%20%28oceanography%29 | Remote sensing in oceanography is a widely used observational technique which enables researchers to acquire data of a location without physically measuring at that location. Remote sensing in oceanography mostly refers to measuring properties of the ocean surface with sensors on satellites or planes, which compose an image of captured electromagnetic radiation. A remote sensing instrument can either receive radiation from the Earth’s surface (passive), whether reflected from the Sun or emitted, or send out radiation to the surface and catch the reflection (active). All remote sensing instruments carry a sensor to capture the intensity of the radiation at specific wavelength windows, to retrieve a spectral signature for every location. The physical and chemical state of the surface determines the emissivity and reflectance for all bands in the electromagnetic spectrum, linking the measurements to physical properties of the surface. Unlike passive instruments, active remote sensing instruments also measure the two-way travel time of the signal; which is used to calculate the distance between the sensor and the imaged surface. Remote sensing satellites often carry other instruments which keep track of their location and measure atmospheric conditions.
Remote sensing observations, in comparison to (most) physical observations, are consistent in time and have good spatial coverage. Since the ocean is fluid, it is constantly changing on different spatial and temporal scales. Capturing the spatial variation of the ocean with remote sensing is considered extremely valuable and is on the frontier of oceanographic research. The high variability of the ocean surface is also the deterministic factor in the differences between land and ocean remote sensing.
Remote sensing of the ocean
Characteristics
Remote sensing is actively used in various fields of natural sciences like geology, physical geography, ecology, archeology and meteorology but, remote sensing of the ocean is vastly different. Unlike most land processes the ocean, just like the atmosphere, is variable on way shorter time scales over its entire spatial scale; the ocean is always moving. The temporal variability in the object of study determines the usability of specific data and the applicable methods and is the reason why remote sensing methods differ materially between ocean and land surfaces. A single wave on the surface of the ocean can not be tracked by satellites of today. Ocean waves crash or disappear before a new observation is made, features with this time scale are rarer on land. Unlike vegetation, snow and other land covers the ocean is opaque to most electromagnetic radiation (except for visible light) therefore the ocean surface is easy to monitor but it is a challenge to retrieve information of deeper layers. Remote sensing enables temporal analysis over vast spatial scale, since satellites have a constant revisit time, provide a wide image and are often operational for multiple consecutive years. This concept of constant data in time and space was a breakthrough in oceanography, which previously relied on measurements from drifters, coastal locations like tide gauges, ships and buoys. All in-situ measurements either have a small spatial footprint or are varying in location and time, so do not deliver constant and comparable data.
History
Remote sensing as we know it today started with the first earth orbiting satellite Landsat 1 in 1973. Landsat 1 delivered the first multi-spectral images of features on land and coastal zones all over the world and already showed effectiveness in oceanography, although not specifically designed for it. In 1978 NASA makes the next step in remote sensing for oceanography with the launch of the first orbiting satellite dedicated to ocean research, Seasat. The satellite carried 5 different instruments: a Radar altimeter for retrieving sea surface height, a microwave scatterometer to retrieve wind speeds and direction, a microwave radiometer to retrieve sea surface temperature (SST), an optical and infrared radiometer to check for clouds and surface characteristics and lastly the first Synthetic Aperture Radar (SAR) instrument. Seasat was only operational for a few months but, together with the Coastal Zone Color Scanner (CZCS) on Nimbus-7, proved the feasibility of many techniques and instruments in ocean remote sensing. TOPEX/POSEIDON, an altimeter launched in 1992, provided the first continuous global map of sea surface topography and continued on the possibilities explored by Seasat. The Jason-1, Jason-2 and Jason-3 missions continue the measurements from 1992 to today to form a complete time-series of the global sea surface height. Also other techniques hosted on Seasat found continuation. The Advanced Very-High-Resolution Radiometer (AVHRR) Is the sensor carried on al NOAA missions and made SST retrieval accessible with a continuous time-series since 1979. The European Space Agency (ESA) further developed SAR with the ERS-2, ENVISAT and now Sentinel-1 missions by providing larger spatial footprints, lowering the resolution and flying twin missions to reduce the effective revisit time. Optical remote sensing of the ocean found continuation after the CZCS with polar orbiting missions ENVISAT, OrbView-2, MODIS and very recently with Sentinel-3, to form a continuous record since 1997. Sentinel-3 is now one of the best equipped missions to map the ocean hosting a SAR altimiter, multispectral spectrometer a radiometer and several other instruments on multiple satellites with alternating orbits providing exceptional temporal and spatial resolution.
Methods
The physical and chemical state of a surface or object have direct impact on the emissivity, reflectance and refractance of electromagnetic radiation. Sensors on remote sensing instruments capture radiation, which can be translated back to deduce the physio-chemical properties of the surface. Water content, temperature, roughness and colour are characteristics often deduced from the spectral characteristics of the surface. A sensor on a satellite returns the composite signal for a certain area inside the footprint called a cell, the size of the unique cells is referred to as the spatial resolution. The spatial resolution of a sensor is determined by the distance from earth and the available bandwidth for data transfer. A satellite passes over the same location consistently through time with the same interval called the revisit-time or temporal resolution. Sensors can not have both a very high temporal and spatial resolution so a tradeoff has to be made specific for the goal of the mission. Sensors on satellites have measuring errors, caused by for example atmospheric interference, geolocation imprecision and topographic distortion. Complete derived products from remote sensing often use simple calculations or algorithms to transform the spectral signature from a cell to a physical value. All methods of transferring spectral data has certain biases which can contribute to the measurement errors of the final result. Often surface characteristics can be deduced with very low error margins due to data corrections, using onboard data or models, and a physically correct translation of spectral characteristics to physio-chemical characteristics.
Although it is interesting to know the surface characteristics at a certain moment, often research is more interested in documenting the change of a surface over time or the transport of characteristics through space. Change detection leverages the consistent temporal component of remote sensing data to analyze the change of surface properties in time. Change detection relies on having at least two observations taken at different times to analyze the difference between the two images visually or analytically. In land remote sensing change detection is used for example: to assess the impact of a volcano eruption, check the growth of plants through time, map deforestation, and measure ice sheet melt. In oceanography the surface changes more quickly than the revisit time of a satellite making it difficult to monitor certain processes. Change detection in oceanography requires the characteristic to change continuously like sea level rise or change spatial scale slower than the revisit time of the satellite like algal blooms. Another way to infer change from only 1 acquisition is by computing the dynamical component and direction from a static image which is leveraged in RADAR altimetry to deduce surface current velocity.
Remote sensing use cases
Sea surface temperature (thermal infrared radiometry)
The ocean surface emits electromagnetic radiation dependent on the temperature at a certain frequency following Planck's law for black body radiation, scaled by the emissivity of the surface since the ocean is not a perfect black body.
With the spectral radiance, the Planck constant; the speed of light and the Boltzmann constant. Most radiation emitted by earth is in the thermal-infrared spectrum which is part of the atmospheric window, the spectral region for which the atmosphere does not significantly absorb radiation. The radiation coming from the earth's surface with a wavelength within the atmospheric window can be captured by a passive radiometry sensor at satellite height. The radiation captured by the sensor is corrected for atmospheric disturbance and radiation noise to compute the brightness temperature of the ocean surface. With a correct estimation of the emissivity of sea water (~0.99) the grey body temperature of the ocean surface can be deduced, also referred to as the Sea Surface Temperature (SST).
To correctly remove atmospheric disturbance, both emission and absorption, the airborne radiometers are calibrated for every measurement by SST measurements in multiple bands and/or under different angles. Atmospheric correction is only viable if the measured surface is not covered in clouds as they significantly disturb the emitted radiation. Clouds are either removed as viable pixels in the image using cloud busting algorithms or clouds are handled using histogram and spatial coherency techniques (up to 80% cloud cover). Radiometry captures the surface skin temperature (~10 micron depth) of the ocean, which significantly differs from bulk SST in-situ measurements. Phenomena close but not at the surface like diurnal thermocline formation are not well captured with satellites but SST can still be of tremendous value in oceanography. Overall satellites measure the SST with a ~0.1-0.6 K accuracy dependent on the sensor and only experience limited issues like surface slicks.
Retrieved SST datasets really transformed oceanographic research during the 1980's and has multiple different uses. The SST is a clear climatological indicator linking to the ENSO cycles, weather and climate change but can also highlight movement of ocean water. SST anomalies can highlight mesoscale eddies, ocean fronts and regions of upwelling, vertical mixing or river outflow as the water is locally more cold or warm due to transport. The SST is directly linked to the horizontal density gradient which is really strong at fronts and is induced by ocean currents and eddies. The currents and fronts are visible in SST images and can be detected using edge detection via high pass filters or kernel transformations to study the dynamics and origin. SST is widely used to track upwelling and river outflow strength as these processes are clearly visible as negative SST anomalies.
Mapping of algal blooms (Optical)
An algae bloom is the enhanced growth of photosynthetic organisms in a water system, which manifests itself as a clear change of water color. Algal blooms are often caused by a local enrichment of the water system with nutrients, which temporarily remove the limiting growth factor of photosynthetic organisms like cyanobacteria. Due to oxygen depletion, blocking sunlight and the release of possible toxins algal blooms can be harmful to their environment. Algae are characterized by their green color, caused by the absorption spectra of the chlorophyll-a in these organisms. Optical satellites like Sentinel-2 or active radiometers like Sentinel-3 and MODIS can capture the reflectance of the ocean surface in the visible and near-infrared spectrum. Areas with a higher concentration of algae near the surface have a distinct different color. The spectral signature of an algal bloom in water is captured by the sensor as a high green and near-infrared radiation reflectance and low red light reflectance.
To map algal blooms thresholding is used in combination with a spectral index like the Normalized Difference Vegetation Index (NDVI). In one observation the intensity and location of the algal bloom can be recorded, and with a second observation at a different time the displacement and intensity change of the algal bloom can be tracked. Algal blooms are used to study internal wave structures, up-welling and river outflows, which all bring nutrients to surface waters, since they are correlated with algae concentration . Pollution often coincides with high nutrient waters, making algal blooms good indicators for the severity and impact of water pollution
Sea surface height (RADAR altimetry)
RADAR altimeters send microwave pulses to the surface and catch the reflection intensity over a short time period measuring the two-way travel time of the signal. Electromagnetic radiation travels with the speed of light thus the two way travel time gives information on the height of the satellite above the surface following the formula . To deduce the sea surface height from the satellite height the two-way travel time has to be corrected for dynamical errors, the atmospheric conditions and the local geoid height . The local change of the sea surface height due to dynamical effects like wind and currents can be expressed using the following formula.
is the dynamic Sea Surface Height (SSH) which changes dependent on wind and current conditions.
is the height of the satellite above the reference ellipsoid which is in the order of a 100 km and is known with a cm precision.
is the height of the satellite above the ocean surface and is the quantity measured by the satellite with cm precision.
is the local height difference between the geoid and the reference ellipsoid which is in the order of ±100 cm and can be estimated using a time series of ocean altimetry data.
is the local height difference due to tidal movements of which the magnitude scales dependent of the time of day.
is the local height difference due to atmospheric pressure difference above the surface.
It is hard to correctly estimate , and for a certain moment and location. As a solution remote sensing analysts use the Sea Surface Height Anomaly (SSHA) which only requires information on the tidal height and atmospheric pressure, which can be deduced from drifters, weather programs and tidal models. The geoid height for SSHA retrieval is deduced from a long time-series of the same RADAR altimetry data. The SSHA is computed by subtracting the temporal mean of the SSH or Mean Sea Surface (MSS) from the current SSH with so that:
Although the SSHA can show anomalies in surface currents of the ocean, often a measure called the Absolute Dynamic Topography (ADT) is computed using an independent measurement of the geoid height to display the total ocean currents.
with the geoid height as a measurement from instruments like the Gravity and Ocean Circulations Explorer (GOCE) or Gravity Recovery and Climate Experiment (GRACE).
With the launch of TOPEX/POSEIDON in 1992 started a continuous time series of global SSH data which, has been extremely valuable in assessing sea level rise in the past decades by combining data with local tide gauges. The dynamical sea surface height from radar altimetry provides useful insight into ocean currents. If assuming geostrophic balance, the velocity anomaly and direction of surface currents perpendicular to the satellite overpass can be computed using the formula:
and for and
With the Coriolis force, the gravity constant, the zonal and meridional velocity and the derived sea surface height anomaly. RADAR altimeters are able to collect data even in cloudy circumstances but only cover the globe up to latitudes ~60 - 65°. Often the spatial resolution of RADAR altimeters is not too high but their temporal coverage is tremendous, allowing constant monitoring of the ocean surface. RADAR altimeters can also be used to determine the specific wave height and estimate wind velocities using the wave form and backscatter coefficient of the pulse limited return signal.
Challenges of Remote Sensing in Coastal Zones
There can be numerous limitations with the sensors and techniques used by remote sensing tools when it comes to mapping coastal regions. Some challenges stem from issues with resolution and pixel size, as most remote imaging satellites have a pixel size of approximately 1 square kilometer. This presents issues with analyzing coastal regions in the desired level of detail as most coastal processes occur on a spatial scale that is approximately the same (or smaller) than the pixel size provided by remote imaging satellites. Additionally, most ocean sensors have a global coverage frequency of 1-2 days, which may be too long to observe the temporal scale of coastal ocean processes.
Furthermore, remote sensing of coastal areas has faced challenges in accurately interpreting the color of the ocean. The color of open ocean basins is mostly controlled by phytoplankton and travel predictably or covary with other constituents in the water column like chlorophyll a. However, as we get closer to the coastlines and move from the open ocean, to shelf seas, to coastal waters, the particles in the water do not covary with chlorophyll. The apparent color may be influenced by optically active constituents in the water column, such as sediments from runoff or pollution. The satellites can also be influenced by "adjacency effects", where the color of the land can bleed into coastal ocean pixels. Finally, removing the effects of the atmosphere is difficult to achieve because of the complex and dynamic mix of coastal aerosols and sea spray. All of these factors can make it increasingly challenging to accurately analyze coastal regions from remote sensing satellites.
Use of UAVs in Remote Sensing
Satellites, while the core of remote sensing, have limitations in their spatial, spectral, and temporal resolution. In an effort to combat these limitations, satellite remote sensing utilizes interpolation and modelling to fill in the gaps. While methods of interpolation and modelling can be developed to a high degree of statistical accuracy, they are in their essence a educated guess based on surrounding conditions. The use of UAVs, or drones, as a remote sensing tool can provide data at higher resolutions that can then be used to fill in the gaps in satellite data, often at a lower price than satellites or crewed aircraft. Notable benefits can be found in the pixel gaps found along coastal areas in satellite data as well as the ability to conduct observations of a given area between satellite passes.
Modern technology has provided UAV users with numerous platforms able to be outfitted with commercial or custom made sensor packages. These sensors consist of multispectral, hyperspectral sensors as well as standard visual spectrum, high definition cameras. The size of modern UAVs is also a factor contributing to their applicability. Satellites and crewed aircraft require shore-based facilities or ships capable of supporting take-off and landing operations. Small-UAVs, those defined as under 55 pounds, have the ability to be launched from nearly every location on shore as well as any size vessel at sea. They require very few crew to operate and flight training requirements are affordable and relatively easy to obtain.
There are some limiting factors to UAV use for oceanic remote sensing. Firstly, the range is limited to the on board fuel or battery capacity as well as distance from the controller. Many governments also impose restrictions on range, stating that UAVs must be flown within unaided visual line of sight. UAV use offshore must be accompanied by a vessel due to these range constraints. Furthermore, the sensors themselves encounter similar challenges to the sensors mounted on satellites, namely in alterations to oceanic reflectance in coastal zones; however, the higher resolution provided by UAV mounted sensors allows for a more diverse assignment of pixels, reducing the blending effect of terrestrial and aquatic environments and reducing the amount of calculations needed to account for reflectance shifts.
References
Remote sensing
Oceanography | Remote sensing (oceanography) | [
"Physics",
"Environmental_science"
] | 3,950 | [
"Oceanography",
"Hydrology",
"Applied and interdisciplinary physics"
] |
67,697,360 | https://en.wikipedia.org/wiki/Webwereld | Webwereld was a Dutch online newspaper about IT by the International Data Group. It was the oldest Dutch technology website until it was discontinued in 2020.
History
Webwereld was founded in 1995 by Oscar Kneppers, who got the idea after visiting Silicon Valley in the summer of that year. Another Dutch tech website Tweakers.net was founded in 1998 after Femme Taken concluded that the moderation on Webwereld was too strict.
In August 2011, Webwereld published about court documents in the Apple Inc. v. Samsung Electronics Co. lawsuit. In October 2011, Webwereld started Lektober (portmanteau of leak and October in Dutch) where they publicized about a security bug every day of the month in a website of a well-known Dutch organization. In 2011, Trans Link Systems considered suing Webwereld because they sold RFID writers that could be used for free traveling in Dutch public transport.
Journalists
Brenno de Winter
References
External links
Computing websites
Dutch-language websites
Dutch news websites | Webwereld | [
"Technology"
] | 210 | [
"Computing websites"
] |
67,698,084 | https://en.wikipedia.org/wiki/Colibactin | Colibactin is a genotoxic metabolite produced by Escherichia coli and other Enterobacteriaceae ("enteric bacteria") believed to cause mutations leading to colorectal cancer and the progression of colorectal cancer. Colibactin is a polyketide peptide that can form interstrand crosslinks in DNA. Colibactin is only produced by bacterial strains containing a polyketide synthase genomic island (pks) or clb biosynthetic gene cluster. About 20% of humans in high-income countries are colonized with E. coli that harbor the pks island.
Colibactin forms DNA inter-strand cross-links by alkylation of adenine moieties on opposing DNA strands. It induces lytic development in certain bacteria that contain prophages. Colibactin has been previously demonstrated to have a characteristic mutational signature. The same mutational signature was discovered in several cohorts of colon cancer patients, and in smaller numbers of patients with urogenital and head and neck cancers.
References
Bacterial toxins
Mutagens
Cyclopropanes
Spiro compounds
Thiazoles
Alkylating agents
Polyketides
Pyrrolines
Carboxamides | Colibactin | [
"Chemistry"
] | 264 | [
"Biomolecules by chemical classification",
"Alkylating agents",
"Natural products",
"Organic compounds",
"Polyketides",
"Reagents for organic chemistry",
"Spiro compounds"
] |
67,698,348 | https://en.wikipedia.org/wiki/Pagh%27s%20problem | Pagh's problem is a datastructure problem often used
when studying lower bounds in computer science named after Rasmus Pagh.
Mihai Pătrașcu was the first to give lower bounds for the problem.
In 2021 it was shown that, given popular conjectures, the naive linear time algorithm is optimal.
Definition
We are given as inputs subsets over a universe .
We must accept updates of the following kind:
Given a pointer to two subsets and , create a new subset .
After each update, we must output whether the new subset is empty or not.
References
Problems in computer science | Pagh's problem | [
"Technology"
] | 122 | [
"Problems in computer science",
"Computer science"
] |
66,205,491 | https://en.wikipedia.org/wiki/Equalized%20odds | Equalized odds, also referred to as conditional procedure accuracy equality and disparate mistreatment, is a measure of fairness in machine learning. A classifier satisfies this definition if the subjects in the protected and unprotected groups have equal true positive rate and equal false positive rate, satisfying the formula:
For example, could be gender, race, or any other characteristics that we want to be free of bias, while would be whether the person is qualified for the degree, and the output would be the school's decision whether to offer the person to study for the degree. In this context, higher university enrollment rates of African Americans compared to whites with similar test scores might be necessary to fulfill the condition of equalized odds, if the "base rate" of differs between the groups.
The concept was originally defined for binary-valued . In 2017, Woodworth et al. generalized the concept further for multiple classes.
See also
Fairness (machine learning)
Color blindness (racial classification)
References
Machine learning
Information ethics
Computing and society
Philosophy of artificial intelligence
Discrimination
Bias | Equalized odds | [
"Technology",
"Engineering",
"Biology"
] | 216 | [
"Behavior",
"Machine learning",
"Aggression",
"Computing and society",
"Discrimination",
"Ethics of science and technology",
"Artificial intelligence engineering",
"Information ethics"
] |
66,205,851 | https://en.wikipedia.org/wiki/Cortinarius%20subsaniosus | Cortinarius subsaniosus is a species of webcap mushroom known from north and central Europe, where it grows on sandy soil in association with willows. It produces small yellowish brown mushrooms. The species was described in 2020 by Kare Liimatainen and Tuula Niskanen. Its name refers to its affinity to C. saniosus, to which it is closely related. Along with five other British webcaps, C. subsaniosus was selected by Kew Gardens as a highlight of taxa described by the organisation's staff and affiliates in 2020.
Taxonomy
Cortinarius subsaniosus was described in a 2020 research note in the journal Fungal Diversity by Kare Liimatainen and Tuula Niskanen. The description was based on a collection made by S. E. Evans in 1999 at Sandscale Haws, a nature reserve near Barrow-in-Furness, Cumbria, England. The specific name refers to the affinity the mushrooms have to C. saniosus. Phylogentic analysis places the species in sect. Saniosi of the genus Cortinarius, along with C. saniosus, C. aureovelatus, C. chrysomallus, and C. aureomarginatus. It has been described as part of the Cortinarius sansiosus species complex in Cortinarius subgenus Telamonia.
Cortinarius subsaniosus was one of over 150 botanical and mycological taxa described by staff or affiliates of Kew Gardens in 2020. In a year-end round-up, Kew scientists selected ten highlights, one of which was six newly described British Cortinarius species: C. subsaniosus described from Cumbria; C. britannicus from Caithness; C. scoticus and C. aurae from the Black Wood of Rannoch; C. ainsworthii from Brighton; and C. heatherae from Heathrow Airport. In a press release, Kew identified Cortinarius species as "ecologically important in supporting the growth of plants, particularly trees such as oak, beech, birch and pine" and playing "a key role in the carbon cycling of woodlands and providing nitrogen to trees".
Description
Cortinarius subsaniosus has a cap that is wide, at first cone-shaped to somewhat convex, later convex to planoconvex (flat on one side, convex on the other) with a pointed umbo. The caps are yellowish brown, often dark brown at the centre, and are hygrophanous. The gills are brown and medium spaced. The stem is long, thick at the apex. They are cylindrical, and yellowish brown. The flesh is generally yellowish brown, though dark brown at the base of the stem. There is a yellow universal veil forming distinct complete and incomplete girdle-like structures on the stem. There is no distinct odour.
Microscopic characteristics
The ellipsoid to almond-shaped basidiospores are 9.5 to 11 by 6 to 7 micrometres (μm), averaging 10.2 by 6.1 μm. The spores are very warty, especially at their apices. The spores are moderately dextrinoid, meaning that they stain a reddish brown when tested with Melzer's reagent or Lugol's solution. The club-shaped basidia are 25 to 35 by 9 to 11 μm, sporting four sterigmata. The hyphae in the flesh of the gills are golden and are mainly smooth with a few spot-like encrustations. The pileipellis is rusty brown. It consists of more or less parallel hyphae that are 5 to 8 μm wide, densely encrusted with zebra-striped incrustations.
Similar species
Cortinarius subsaniosus is reminiscent of C. saniosus, though the latter has somewhat smaller spores, measuring 8.5 to 10 by 5 to 6.5 μm.
Ecology
Cortinarius subsaniosus associates with trees, including at least willows (Salix), but perhaps others. Collections have been made in the United Kingdom, Denmark, Estonia, Norway, Sweden, and Finland. It appears to be rare inland.
References
subsaniosus
Fungi described in 2020
Fungi of Europe
Fungus species | Cortinarius subsaniosus | [
"Biology"
] | 903 | [
"Fungi",
"Fungus species"
] |
66,206,864 | https://en.wikipedia.org/wiki/Infinity%20cube | An Infinity cube is a kind of mechanical puzzle toy with mathematical principles. Its shape is similar to a 2×2 Rubik's cube. It can be opened and put back together from different directions, thus creating a visually interesting effect.
Construction
The principle of the infinity cube is simple and can be made by hand with simple paper cutting and pasting. First make 8 small cubes, then arrange the small cubes in a 2 by 2 by 2 way, and tape 8 edges together. When combined, there are 28 small squares exposed and 20 small squares hidden inside.
Mathematics
Like the Rubik's Cube, the various states of the Infinity Cube can be represented as a group, but the Infinity Cube has far fewer permutations than the Rubik's Cube.
Rubik's Cube group have permutations and isomorphic to the below group, where are alternating groups and are cyclic groups:
The largest group representation for Infinity Cube only contains 6 elements, and can be represented as:
See also
Paper model
Fidget Cube
15 puzzle
References
External links
Magic Folding Cube - Mathematische-Basteleien
Rubik's Cube
Origami
Novelty items
Mechanical puzzles
Sensory toys | Infinity cube | [
"Mathematics"
] | 242 | [
"Recreational mathematics",
"Mechanical puzzles"
] |
Subsets and Splits
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