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76,205,712 | https://en.wikipedia.org/wiki/Mark%20of%20the%20Web | The Mark of the Web (MoTW) is a metadata identifier used by Microsoft Windows to mark files downloaded from the Internet as potentially unsafe. Although termed the "Mark of the Web", it is sometimes also found on files from other sources perceived to be of high risk, including files copied from NTFS-formatted external drives and themselves downloaded from the web at some earlier point.
It is implemented using the alternate data stream (ADS) feature of Microsoft's default NTFS filesystem. Due to its reliance on features exclusive to NTFS, transferring the file to or from a partition with an alternative filesystem, such as FAT32 or Ext3, will strip the file of its ADSs and thus the mark. These alternate streams are intended to be transparent (i.e. hidden from most users) and are not shown to or made editable by users through any GUI built into Windows by default.
A second type of MotW can arise when saving a webpage as an HTML document, as most browsers will insert an HTML comment in the process while noting the URL from which the document was saved. This form of mark is significantly different in that it is clearly accessible to users and is embedded within the file itself, rather than the ADS metadata, making it easy to manually spot and remove.
The mark was added by all versions of Internet Explorer supported by Windows 7 and later. Without deep modifications to the source code, all Chromium (e.g. Google Chrome) and Firefox-based web browsers also write the mark's stream to downloaded files. All of these browsers additionally add the second type of mark in the form of the source URL of downloaded webpages as a HTML comment at the beginning of the file. Chromium and Firefox-based browser marks contain the domain name and exact URL of the original online download location, potentially offering a deeply esoteric method of tracking browsing history with concomitant privacy risks.
Effects
Windows warns users attempting to open a Web-marked file that it was downloaded from the Internet and could be harmful; the user can opt either to continue or cancel execution. If the file is executable and the user opts to override the warning, the mark will be removed from the file in order to prevent the same prompting each time. Unless overridden by user action, the mark prevents macros from running in Microsoft Office files. Visual Studio projects created with Web-marked files cannot be built or executed.
Some archiving software propagates the MoTW from the archive itself to files extracted from it, preventing its security protection being bypassed by malware distributed within an archive.
If the downloaded file is an executable (e.g. an installer), the mark stream can be used for reflection, enabling the program to identify from where it was downloaded, which is occasionally used for telemetry and/or security purposes. A program can attempt to verify that it was downloaded from an official source (assuming the stream has not been removed or spoofed) and can transmit this information back over the internet (an example of this in action is BiglyBT's installer).
Implementation
ADS is a form of fork allowing more than one data stream to be associated with a filename/file using the format filename:streamname (e.g. notepad.exe:extrastream). Although intended for helpful metadata, their arcane nature makes them a possible hiding place for potentially unwanted information, including, in the case of the MoTW, the browser history associated with the downloaded file.
In the case of the mark, the ADS is named Zone.Identifer. As of Windows 10, the contents of the Zone.Identifer stream are structured like an INI file (i.e. a key-value store) that includes the keys HostIpAddress, HostUrl, and ReferrerUrl. To some extent, these are implementation-defined fields, but they typically contain the domain name and exact URL of the original online download location.
Bypasses, security, and privacy concerns
There have been several Windows vulnerabilities that have enabled malicious actors to fully or partially bypass the mark or allowed it to be used in the proliferation of malware by e.g. hiding code. Many or all of the known exploits have been corrected by patches. Due to the privacy concerns associated with the mark and the Zone.Identifier stream, including the storage of the exact domain name and origin URL of the file, there exists software specifically designed to strip the information from files in a user-friendly way.
An exploit with the Common Vulnerabilities and Exposures (CVE) identifier CVE-2022-41091 was added to the National Vulnerability Database on November 8, 2022, and refers to the now-patched ability of a malicious actor to avoid files downloaded from the Internet being marked. Other vulnerabilities (CVE-2022-44698, patched in December 2022 and CVE-2023-36584, patched in October 2023) allowed malicious actors to bypass the restrictions of the mark without removing it. In September 2024, another exploit (CVE-2024-38217) was found that, under some circumstances, allowed the full removal, and thus bypass of all detection, of the mark, and was additionally found to be in active use in the wild. It has also since been patched.
An attacker may also use social engineering to convince a target user to unblock the file by right-clicking it and changing the file properties.
References
Windows administration
Cybersecurity engineering | Mark of the Web | [
"Technology",
"Engineering"
] | 1,176 | [
"Cybersecurity engineering",
"Computer networks engineering",
"Computer engineering"
] |
76,206,157 | https://en.wikipedia.org/wiki/Birds%20of%20the%20World | Birds of the World (BoW) is an online database of ornithological data adapted from the Handbook of the Birds of the World and contemporary reference works, including Birds of North America, Neotropical Birds Online, and Bird Families of the World. The database is published and maintained by the Cornell Lab of Ornithology and collects data on bird observations through integration with eBird. The database requires a subscription to access the majority of its entries, but offers institutional access to many libraries and birding-related organizations, participating in the National Information Standards Organization's Shared E-Resource Understanding practice as a publisher.
The database is frequently cited in regional checklists and distribution map studies, either as a point of comparison or a source of data.
History
Birds of the World was originally developed in the early 1990s through collaboration between the American Ornithologists' Union, the Cornell Lab of Ornithology, and the Academy of Natural Sciences of Drexel University. The goal of the project was to produce an illustrated guide to all of the birds of the world; its first iteration was in the 17-volume Handbook of the Birds of the World, published by Lynx Edicions over the course of 22 years, from 1992 to 2014. After the Cornell Lab of Ornithology acquired the rights to the contents of the Handbook of the Birds of the World, the online database was launched in March of 2020.
A significant portion of the audiovisual content available in Birds of the World is collected through citizen science data collection as provided by eBird, but content is also included from the Macaulay Library, as it was gathered in the Internet Bird Collection by Josep del Hoyo, the initial founder of Lynx Edicions, and his colleagues in 2002.
Description
Birds of the World is a subscription-access database that aims to describe comprehensive life history information on birds. This includes:
Species accounts
Details on taxonomy, habitat, breeding, diet, and behaviors
Family accounts
Hybrid and subspecies descriptions and photos
Migration and range maps
IUCN Conservation Status
Literature cited
Common names in multiple languages
Free resources
Birds of the World provides various resources other than those provided with an institutional or individual subscription to the service. James A. Jobling's Dictionary of Scientific Bird Names, which would be published by Lynx Edicions as the HBW Alive Key to Scientific Names In Ornithology, is accessible as a searchable database on the Birds of the World website, allowing for free access to the definitions of the various scientific names of birds. The HBW Alive Key has been the underpinning for developments between the Cornell Lab and BirdLife International to produce a unified checklist of the birds of the world, and is currently used to form the list of bird species on the IUCN Red List.
References
External links
Birds of the World website
The Key to Scientific Names on Birds of the World
2020 introductions
Biodiversity databases
Birdwatching
Citizen science
Cornell University
Ornithological citizen science | Birds of the World | [
"Biology",
"Environmental_science"
] | 595 | [
"Biodiversity databases",
"Environmental science databases",
"Biodiversity"
] |
76,206,424 | https://en.wikipedia.org/wiki/Oil%20reserves%20in%20France | In 2020, oil reserves in France were equivalent to 1% of its annual consumption. These reserves in the geological sense (extractable oil present in deposits) should not be confused with the strategic reserves of three months' full consumption, which can be used in the event of a serious international crisis. In fact, as a member of the International Energy Agency (IEA), France must maintain oil reserves equivalent to 90 days' net imports, corresponding in 2010 to around 17 million tonnes.
Reserves and production
France's oil reserves are mainly distributed between the Paris Basin and the Aquitaine Basin.
In 1939 production in mainland France was around 50,000 tonnes, for a fuel consumption of three million tonnes.
Between 1956 and 2017 the French government received more than 1,700 applications for exploration permits (applications for exclusive permits to explore for liquid or gaseous hydrocarbons) and granted more than 600. These led to the granting of 77 exploitation titles (concessions for liquid or gaseous hydrocarbons), mainly in the Paris Basin, the Aquitaine Basin and the Rhine Graben. During this period, France produced around 100 million tonnes of oil and 300 billion cubic metres of natural gas (245 Gm3 from the Lacq field alone, 56 Gm3 from Meillon). Some 4,000 exploration and production wells have been drilled.
In the 2000s, around 20,000 barrels of crude oil were extracted every day from the two regions (55% from Île-de-France and 45% from Aquitaine), representing 0.7 Mtoe by 2020. However, exploitable reserves are far greater than those exploited, due to the existence in the Paris Basin's subsoil of oil trapped in the Permian (end of the Primary Era) and Lias (middle of the Secondary Era). In 2016, this represented 815,000 tonnes of oil, or around 1 % of its consumption. These reserves represent 28 years of exploitation at the 2020 rate and three and a half months of national consumption.
The main producer at that date is the Canadian company Vermilion Energy, which has been operating in France since 1997, and at that date accounted for almost three-quarters of French production, i.e. 12,600 barrels a day at the start of 2016. At the beginning of 2017, the other main producers were Lundin Petroleum (Sweden), which during the year transferred its activities in France to a new company, International Petroleum Corporation, based in Canada, Geopétrol, Petrorep (the first company to discover commercially exploitable oil in the Paris Basin in 1958) and Société pétrolière production exploitation.
In the 2010s these activities generated annual direct and indirect sales of between €500 million and €1 billion, providing several thousand direct and indirect jobs in France and generating tax revenues of around €150 million a year. In 2014, the Union française des industries pétrolières estimated that "the total workforce in the para-oil and para-gas sector in France is 65,000, with 50 % of activities linked to hydrocarbon exploration and production".
In December 2017 a law was passed phasing out hydrocarbon exploration and production in France by 2040. As a result, no new hydrocarbon exploration permits can now be granted in France by the government. However, it is still possible to extend existing permits. No new exploitation permits may be granted either, unless the application is made during the period of validity of an existing exploration permit. Existing operating permits may not be extended beyond 2040, unless the company requesting the extension demonstrates that it has not covered its research costs by exploiting the deposit.
Oil reserves and production in the Paris Basin
More than two thousand wells have already been drilled, and over 285 million barrels of oil were produced in the Paris Basin in 2011, out of a total reserve estimated at between 60 and 100 billion barrels.
But in the absence of new exploration, this production is gradually dwindling and is in danger of disappearing. The main deposits are Chaunoy, Itteville and Villeperdue.
Production in the Paris Basin dates back to the 1950s, when France set its sights on oil self-sufficiency and began a series of major research programs in the Seine-et-Marne region.
The first oil discovery was made on February 22, 1958, at 7:02 pm, at a depth of 1,875 m in the subsoil of the village of Coulommes.
This deposit has produced around two million tonnes of oil, but of the fifty-seven wells drilled on the concession since 1958, only four are still active in 2011.
Other discoveries followed in the 1960s. It was also during this period that Seine-et-Marne's only refinery, the Grandpuits refinery supplying Paris, was inaugurated in 1967 in the presence of then Prime Minister Georges Pompidou. Today, it still employs 400 people.
In 1982 and 1983, the Villeperdue and Chaunoy fields were discovered. The former by Triton (later operated by Total, then Coparex, which became Lundin in November 2002) and the latter by Esso. By the end of 2002, Chaunoy had produced a total of 9.8 Mt of oil and Villeperdue 5.8 Mt.
The last significant discovery was made by Elf in 1990 (Itteville). At that time, however, oil activity in the Paris Basin was poor, and no further significant discoveries had been made. In 1992, only nine wells were drilled, compared with 33 in 1991.
Several discoveries were made in the 1990s, and more recently in 2003–2004.
At the same time, however, a number of French wells were shut down and exploration suspended as the price of oil fell below nine dollars a barrel (the break-even point was 15 dollars a barrel).
With the price of a barrel of oil now at $100 in 2011, it is once again becoming economically viable to prospect in the Paris Basin.
The oil companies currently exploiting oil in the Paris Basin are seeking to make progress in two parallel areas: increasing extraction yields, which are currently only 25% per well, and continuing exploration.
Oil reserves and exploitation in the Aquitaine Basin
The three main oil fields in the Aquitaine Basin are Parentis, Cazaux and the Arcachon pool.
Following the discovery of oil in the village of Gabian (Hérault) in 1924, and that of Saint-Gaudens (Haute-Garonne) on July 14, 1939, France's largest oil field, Parentis-en-Born, was discovered by Esso on March 25, 1954.
Since then, around 20 deposits have been discovered in the Aquitaine Basin. Most of the activity is concentrated in the Adour–Arzacq sub-basin, which covers more than 6,000 km2, with 4.7 wells per 100 km2. The Parentis sub-basin, on the other hand, has a higher density of exploration drilling (around 8 wells/100 km2).
On the Cap Ferret peninsula, wells are being drilled to tap an oil table at a depth of 3,200 m, part of the resources of the Aquitaine basin. The Cap Ferret well, opened in 1962, used a deviated borehole to tap the "Lavergne" deposit located under the sea between the Pointe and the Banc d'Arguin. It was shut down in 1994 by ESSO-Rep, an Exxon subsidiary and former operator, due to low flow rates. The well was moved further north due to erosion.
In 2010 the oil company Vermilion, which bought the oil fields from Esso, was authorized to re-exploit the "Lavergne" field in Cap Ferret until 2029, and to drill additional wells.
In 2023, Vermilion intends to increase the exploitation of its "Cazaux" concession in the La Teste forest by drilling additional wells. This project is incomprehensible to environmentalists in view of the announced 2040 deadline for the cessation of all hydrocarbon production in France.
The hydrocarbons are transported via a pipeline to the Bec d'Ambès.
Oil reserves and production in Alsace-Lorraine
Merkwiller-Pechelbronn, 50 kilometers from Strasbourg, was one of the first oil fields in the world to be exploited (using a system of underground galleries rather than boreholes), from the time it was founded in 1740 by Louis Pierre Ancillon de la Sablonnière until December 31, 1964, when it was finally shut down. At the time, the area was known as "Karichschmiermann land" (the land of the mineral grease merchant who sold this axle-lubricant with his wheelbarrow). It produced a total of 3.5 million tonnes of oil, almost 30 million barrels.
At its peak in the 1920s Alsatian crude production exceeded 70,000 tonnes a year, representing 7/8ths of French production and 5% of national requirements. As of 2014, thirteen wells, most of them recent, are in operation in Bas-Rhin, extracting 8,000 tonnes of crude a year, which are refined in Karlsruhe, Germany, since the closure of the Reichstett Refinery in January 2011.
The Sion Hill in Meurthe-et-Moselle was an oil production site at the end of the 20th century. About 13,698 tonnes of "light crude" quality were extracted from the Forcelles subsoil between May 27, 1983, and December 31, 1998.
Unconventional oil reserves and production
Shale oil is light oil contained in porous, low-permeability geological formations, often shale or sandstone. Some consider that it would be "more accurate to speak of 'bedrock' oil or gas, rather than 'shale'".
In France their production has been anecdotal. During the Creveney shale mining operation in the 1930s, 20,000 tonnes of shale were extracted, yielding 500 tonnes of crude oil, 90 tonnes of gasoline, 62 tonnes of refined gasoline, 25 tonnes of refined heavy gasoline, 36 tonnes of diesel, 135 tonnes of heavy oil and 220 tonnes of bitumen. By 1933, the plant was capable of producing 5,000 liters of crude oil per day, which in turn yielded 2,000 liters of gasoline. Industrial production took place mainly in the Autun area between 1824 and 1957, in particular at the Télots mine, which was equipped with a refinery as well as an oil distillation plant.By 2010, 64 exploration permits had been issued for oil and gas, 15 of which were for unconventional hydrocarbons. In fact, according to an assessment by the EIA (U.S. Energy Information Administration), France and Poland are the European countries with the largest shale gas resources. The two basins potentially rich in shale hydrocarbons in France are the northeast and southeast quarters of the country.
In the south-west, under a prospecting permit granted by the French government in 2006, known as the "Permis de Foix", Canadian company Encana drilled two exploratory wells for shale gas in 2007, one year at Franquevielle and 4 months at Mérigon. The deposits were deemed insufficient for further exploitation. These prospective drillings, authorized by the French government with little information for local populations, contributed to the lively controversy over this type of fossil fuel and its extraction methods.
The law of July 13, 2011 repealed permits for projects involving the exploitation of reserves by hydraulic fracturing.
In overseas territories
New discoveries
In September 2011 a consortium comprising Tullow Oil, Shell, Total and Northpet announced that it had found unconventional oil offshore Cayenne in French Guiana. This potential deposit is buried 150 kilometers northeast of Cayenne under more than 2,000 meters of water and 5,711 meters of rock below the seafloor. The well is called "Zaedyus".
The site was considered highly promising by oil analysts, and the French government estimated that, if the site's potential was confirmed, the discovery could have significant economic spin-offs.
In mid-2012 oil company Shell received authorization to start exploration drilling. The two subsequent drillings in December 2012 and April 2013 failed to confirm the presence of the reserves previously announced.
Refining capacity
In 1975 France had twenty-four refineries. In 2009, the number was twelve, with an annual refining capacity of less than 100 million tonnes. In 2011, there were eleven refineries in operation, ten of which are located in mainland France. In 2014, there are still eight sites in operation in mainland France, capable of refining 70 million tonnes a year.
In 2010 Total decided to close its Flandres refinery, and in 2011, a distillation unit at the Gonfreville refinery. In the same year, Petroplus announced the closure of its Reichstett refinery. In 2012, the Petit-Couronne refinery near Rouen and the Berre-l'Étang refinery also closed, and the Provence refinery ceased refining in 2016. By 2020–2030, public authorities and industry professionals believe that, given forecasts of falling consumption of petroleum products, one or two more refineries will close, in the absence of investments to boost their competitiveness and a rebalancing of demand for gasoline and diesel.
See also
Petroleum
Oil and gas reserves and resource quantification
North Sea oil
Les Télots Mine
Fracking
Oil well
Mining in France
References
Petroleum industry in France
France
France | Oil reserves in France | [
"Chemistry"
] | 2,757 | [
"Petroleum",
"Petroleum by country"
] |
76,206,595 | https://en.wikipedia.org/wiki/Gulfstream%20%28tank%20barge%29 | MV Gulfstream is a capsized unpowered double-hulled barge, part of an articulated tug and barge system, without a registration number. The vessel capsized on 7 February 2024 and was abandoned by the crew. It caused a huge spillage of oil in the Caribbean Sea.
History
In February 2024, the barge, carrying an estimated 35,000 barrels of fuel oil, capsized after running aground on a reef some off the south coast of Tobago. The circumstances of the capsizing are not yet clear. The oil spill has spread to Grenada and could potentially affect Venezuela.
The Government of Trinidad and Tobago confirmed the situation and considered declaring a national emergency. It has reportedly affected the fishing and tourism industries. The National Office of Disaster Preparedness and Management (ODPM) said that the oil spill had affected around 15 kilometres (9 miles) of the coastline. Emergency workers were sent to run a major clean up operation. Authorities are attempting to pinpoint the ship's origin.
Farley Augustine, the Chief Secretary of Tobago, said: 'We need those responsible to come clean and we need those responsible to know that they have to pay for this mess, that they are culpable as part of this mess'.
This reportedly threatens an environmental catastrophe. According to Bellingcat, the barge may have started leaking oil on 7 February. The identity and whereabouts of the tug that was hauling the barge are not yet known. By 28 February, oil began to wash ashore on Bonaire in the Leeward Antilles. These beaches are hundreds of miles away from where the ship capsized.
On 21 August 2024, the Government of Trinidad and Tobago confirmed that the barge had been successfully re-floated.
References
Maritime incidents in 2024
Oil tankers
February 2024 events in North America
Oil spills
Shipwrecks in the Caribbean Sea
2024 in Trinidad and Tobago
Environmental disasters in North America | Gulfstream (tank barge) | [
"Chemistry",
"Environmental_science"
] | 385 | [
"Oil spills",
"Water pollution"
] |
76,207,111 | https://en.wikipedia.org/wiki/Dissoderma%20odoratum | Dissoderma odoratum is a species of fungi in the family Squamanitaceae. It is a distinctly strong-smelling species with small, purple sporocarps. The fungus parasites in the sporocarps of the veiled hebeloma (Hebeloma mesophaeum), which are deformed by the parasitic fungus. Dissoderma odoratum is mostly found in Europe but has also been found from the United States. The fungus is a rare species that is classified as endangered in several European countries.
Description
The sporocarps of D. odoratum are small and short-legged. They grow in clusters on the sporocarps of the Hebeloma mesophaeum. There can be more than ten sporocarps in one cluster, but they can also rarely grow individually.
The pileus and the upper part of the foot are coarsely scaly. The base color of the pileus is lilac gray-brown, but the scales are darker. The pileus is convex, usually 1–3 centimeters wide. The lamellae, whitish at first and later light purple or color of the pileus, are quite far apart. The stipe is whither than the pileus. The spore dust is light yellow and the spores are inamyloid (meaning that the fungus does not change color in Melzer's reagent), thin-walled and ellipsoid or ovoid in shape. The length of a spore is 6,5–9,5 micrometers and width 4–6 micrometers.
D. odoratum is an easily identifiable mushroom. The species has a strong sweet scent, which has been as caramel-like or fruity.
Habitat
The habitat of D. odoratum is determined by the presence of its host species. The host species is a mycorrhizal fungi that usually grows with pine, spruce, beech, willow or birch. The host species is found from a variety of habitats, such as deciduous and coniferous forests, sand dunes, parks and gardens.
A significant part of observations have been recorded from human-modified areas, such as in the edges of public paths and lawns. It has been suggested that H. mesophaeum could be more vulnerable to parasitism in human-made environment.
The fungus can grow in a suitable habitat for a long time. For example, in Switzerland, the species grew in the same place for more than 13 years. It is unclear how this is possible, as the fungus is known to be parasitic only on spores and not on underground fungal mycelium. One possibility is that the species leaves chlamydospores behind, which always re-germinate on the sporocarps of the host.
Ecology
D. odoratum is a parasitic fungus that transforms its host's sporocarp into ochre-colored, tuber-like deformity where the original cap and foot have atrophied. The deformation, consisting of the host's swollen trama and the filaments of the parasitic fungus is no longer recognized as a veiled hebeloma, but it may still smell and taste like radish.
Among the parasitic fungi of its family, the D. odoratum is the only one whose host species is known to belong to the genus Hebeloma. Because the fungus grows on spores that are deformed beyond recognition, it took a long time to confirm its host fungus. However, the species had been found in Denmark in association with the veiled hebeloma, which gave it a candidate as a possible host species. Confirmation of the matter was obtained with a molecular study published in 2007. It is not known whether the fungus also grow on other species of Hebeloma.
Several other species of the same genus are poisonous. The fungi is inedible and has been described as potentially poisonous.
Distribution
The fungus was originally found from The Netherlands in 1915. The species was first considered endemic, but in 1948 it was found in Denmark and later from other European countries. By 2016 the fungi was also found from Belgium, Great Britain, Italy, Norway, Poland, France, Sweden, Germany, Finland and Switzerland.
In the 2020s, studies have been published using metabarcoding based on DNA sequencing of environmental samples have been published. This way the presence of D. odoratum in Estonia and Latvia was revealed although no spores have been found. Based on the environmental samples, the species seems to occur in Russia as well.
D. odoratum is primarily a European species, but in 1951 it was found in the Washington state in the United States. Species identification was genetically confirmed in 2022, and it is the only discovery from North America so far. The observations from Japan were found to represent a different species Dissoderma phaeolepioticola, whose host species is the golden bootleg (Phaeolepiota aurea).
Endangerment
The International Union for Conservation of Nature (IUCN) has not assessed the endangerment of the species. The species is considered very rare worldwide.
Taxonomy
The fungus was first described by Dutch mycologist Catharina Cool in 1918 as Lepiota odorata. In 1946 Emil J. Imbach described genus Squamanita where the fungus was placed in to as Squamanita odorata. In 2022 Squamanita was split in half, because according to phylogenetic analysis the genus was paraphyletic. The species was moved to genus Dissoderma. Although the fungus is not the type species of its genus, it is the species known for the longest.
References
Squamanitaceae
Fungi described in 1918
Parasitic fungi
Fungi of Europe
Fungi of the United States
Fungus species | Dissoderma odoratum | [
"Biology"
] | 1,187 | [
"Fungi",
"Fungus species"
] |
76,207,646 | https://en.wikipedia.org/wiki/Nanshitou%20massacre | The Nashitou massacre () was large-scale unnatural deaths among the refugees detained by the Imperial Japanese Army and Wang Jingwei regime at the Nanshitou Refugee Camp in Guangzhou, China, between 1942 and 1945. The event was triggered by the Japanese expulsion of Chinese residents from Japanese-occupied Hong Kong in 1942, which resulted in refugees crowding into the city of Guangzhou by ferry along the Pearl River. They were stopped at Nanshitou for physical examinations. A former soldier of Unit 8604 stated that the unit was instructed to poison Chinese refugees with the pathogens of typhoid and paratyphoid, which they put into the thin porridge and drinking water prepared for the refugees, causing a large number of deaths. Additionally, survivors claimed that the Japanese used detainees for human experimentation. In the 1950s and 1980s, Guangzhou Paper Mill found a massive amount of human skeletons and bones during construction projects, which were believed to be victims of the refugee camp. Chinese scholar Tan Yuanheng asserts that at least 100,000 died in the refugee camp.
Background
Expelling of Chinese from Hong Kong
In October 1938, following the Japanese occupation of Guangzhou, 100,000 to 200,000 Guangzhou residents fled Hong Kong due to the historical ties between the two cities. The Japanese took British Hong Kong in December 1941, following its attack on the Pearl Harbour. The Japanese military authorities considered the massive Chinese population in Hong Kong could be a burden to the city and soon began expelling Chinese from the city.
By 19 February 1942, 554,000 individuals had been repatriated. Subsequently, a governor's office was established in Hong Kong, overseeing the expulsion of another 419,000 people by the end of September 1943. It is estimated that a significant portion of refugees returning to Guangzhou by sea numbered at least 150,000 or more. In April 1944, the Hong Kong Occupied Territories Government halted rice distribution to the general population. The surge in repatriates prompted the cessation of encouraged evacuation in July. By the time of Japan's surrender, Hong Kong's population had dwindled to 600,000.
Nanshitou refugee camp
The refugee camp at Nanshitou was a prison in the south suburb of Guangzhou, which had a dock upon the Pearl River. It was turned into a refugee camp, with the surge of refugees arriving from Hong Kong until the Japanese surrender in 1945. As the number of refugees was far above the capacity of the camp, ferries carrying refugees were anchored on the Pearl River near Nanshitou. The refugees were prohibited from leaving Nanshitou and forced them to work for the Japanese or Wang Jingwei authorities.
Unit 8604
By the end of 1939, the Imperial Japanese Army in Guangzhou had organised Unit 8604, purportedly tasked with providing epidemic prevention water supply for the Japanese army. However, its actual activities involved bacteriological research and bacteriological warfare. While the refugee camp was run by the Guangdong Provincial Government under the Wang Jingwei regime, Unit 8604 took control of the epidemic prevention in the camp, where the unit secretly murdered refugees with bacteriological weapons and experimentations.
Refugee camp
Quarantine processes
According to eyewitness accounts, the quarantine process roughly proceeded as follows: Upon anchoring the ships, quarantine procedures were conducted, whereby individuals suspected of being infected were isolated and taken away, while the rest were driven back onto the ships. Quarantine inspections sometimes took place on board, at other times at the Yuehai Customs Harbor Quarantine Office, and occasionally on the riverbanks or flat ground ashore. The so-called quarantine procedure involved "men, women, old, and young being forced to strip naked, exposing their buttocks upwards," followed by rectal examinations using glass rods. However, in Japanese military records, there is no detailed documentation regarding the specific quarantine procedures for refugees in the so-called "refugee camps on board ships." Furthermore, if thermometers were used, this step alone would not accurately detect infectious diseases. If sampling probes were used, questions arose regarding whether there were registration numbers, and how large quantities of samples were stored and tested, among other issues. It is unlikely that standard quarantine procedures would lead to the destruction of relevant documentation. Due to the limited capacity of the Nanshitou Refugee Camp, which could accommodate only about 5,000 people at most, many refugees were initially placed on refugee ships awaiting processing. Once the camp reached full capacity, refugees were transferred to the camp, and this cycle repeated as needed.
High death toll
Survivors typically described that there was a significant decrease in the number of people aboard the ships. Some refugees couldn't endure the waiting period and died on the ships, mostly due to starvation or disease, with some potentially being caused by the spread of pathogens. While fleas were typically absent on board, some refugees recalled sudden infestations of fleas, followed by a succession of deaths, with "people dying every day," and the deceased being thrown into the river. Refugees believed this was the result of the deliberate dissemination of fleas carrying pathogens by the Japanese. Others attempted to escape secretly.
After the establishment of the Guangdong Provincial Infectious Diseases Hospital by the Japanese following the Customs Quarantine Station at Nanshitou, it was purported to be for the centralized treatment of cholera among Cantonese-Hong Kong refugees, with the cholera outbreak in Guangzhou attributed to the refugees. Locals referred to this hospital as the "Japanese Hospital." According to records from the Japanese hospital, Hong Kong refugees were generally in a state of starvation, with 90.1% suffering from malnutrition, which was the leading cause of death. Among those afflicted with cholera, the highest mortality rates were observed in individuals aged 1 to 10 and 61 to 70, reaching 60-70%. After the age of 40, mortality rates increased significantly. Mortality rates for other age groups ranged from 40 to 70%. Deaths were concentrated in July, during the warmer months, and mortality rates sometimes reached 90% between July and September. Therefore, research suggests that the mortality of cholera is most strongly correlated with temperature rather than gender. When patients experienced severe diarrhoea, mortality rates could reach 40%; with vomiting, mortality rates rose to 57.1%. The mortality rate for patients who vomited five times a day reached 24.7%. Additionally, 52.2% of patients experienced spasms: 31.8% in the upper limbs, 47.8% in the lower limbs, and 20.4% in both upper and lower limbs.
Human experimentation
Japanese records show that Unit 8604 allegedly contacted the Army Military School in Tokyo for the disposal of the refugees. The School requested information regarding the infection rates and death tolls of the bacteria they provided. The unit then decided to experiment on refugees and visualised their results in figures and tables. The infected Chinese people were also sent north to the Chinese-controlled area to infect the Chinese army, in order to alleviate the pressure faced by the refugee camp.
According to a former soldier of the unit, they brought a strain of intestinal salmonella from the Army Medical School in Tokyo and chose to delay the soup supply during breakfast time when provincial government officials were not yet on duty. They took advantage of the refugees' unfamiliarity with the routine and chaotic conditions to secretly release the bacteria while avoiding the destruction of salmonella due to high temperatures.
The use of salmonella, such as typhoid-like strains, in bacteriological warfare is related to their pathological characteristics. These bacteria, when ingested through contaminated water sources, dust, etc., enter the human body via the digestive tract and can rapidly cause severe infection. Even those who are asymptomatic or have mild infections can continue to carry the bacteria, some for several years, thereby spreading the infection widely among both military personnel and civilians during acute outbreaks. Moreover, the ability of asymptomatic carriers to harbour the bacteria for extended periods and over broader geographical areas contributes to greater harm to more individuals over a longer period of time.
The Customs Quarantine Station located in the west of Nanshitou served as a live testing ground for the Japanese bacteriological weapons. Witnesses reported that the Japanese selected young people and sent them into the quarantine station to be fed on by mosquitoes. Tai Wei, a villager from Nanshitou, identified that the Japanese captured mosquito larvae in the rice fields, had people feed the mosquitoes, and then extracted the mosquito blood for experimentation. His brother-in-law was seized and fed to mosquitoes in the quarantine station, only to succumb to illness afterward. According to survivor Feng Qi's account, refugees in the camp were forcibly administered vaccination shots. Many developed high fevers and convulsions shortly after receiving the injection, and within days, they died.
Disposal of corpses
The provincial government of the Wang Jingwei regime was responsible for burying the deceased, employing the method of on-site burial where bodies were stacked together. Even the soil used for burying the bodies became increasingly scarce.
Japanese records only mentioned the deaths of over 300 people and revealed that the outbreak of cholera led to a significant reduction in population, necessitating the commencement of cremation and the use of two large pools to allow natural decay of the bodies. Each pool could accommodate 50–60 bodies at a time, alternating between the two pools. Therefore, the number of deaths far exceeded 300 people.
Zhong Ruirong, an elderly resident of Nanshitou, pointed out that there were two huge pools in the refugee camp at that time to handle the bodies. After each layer of bodies was laid down in the pits, an unknown liquid was poured in, followed by a layer of lime. Within just two or three days, the two pools were filled with bodies. Feng Qi, a survivor of the refugee camp, noted that after the pools were filled with bodies, they were sealed with additional liquid, emitting a foul smell.
According to Xiao Zheng, a retired worker from the Guangzhou Paper Group and a victim of bacteriological warfare, his father witnessed both pools in the refugee camp being filled with skeletal remains, and it took six grave diggers several months to clear them. After the refugees died, they would be transported to the area around Nanji Road for burial.
Memorial
The present location of the Nanshitou Refugee Camp Quarantine Station is situated opposite 44 Xinglong Street, West Nanshitou Road, Nanshitou Subdistrict, Guangzhou. Originally, it served as the office space for the Guangzhou Public Security Bureau's Water Division. The refugee camp was located in the vicinity of the former motorcycle factory and surrounding enterprises.
In 1995, a memorial monument for the Cantonese-Hong Kong refugees was established in the Guangzhou Paper Mill Dormitory Area. In 2002, the Quarantine Station was registered as a protected cultural site in Guangzhou under the name "Former Site of Guangdong Customs Quarantine Station." In 2012, the Haizhu District Government named the unit the "Former Site of the South China Epidemic Prevention and Water Supply Department of the Invading Japanese Army." In 2016, the Haizhu District Government and the Guangzhou Paper Group funded the construction of the area into a green square. In 2018, the Guangzhou Municipal Government announced plans to establish the Cantonese-Hong Kong Refugee Park.
Discovery of the remains
In October 1947, the Guangzhou municipal government relocated the remains from Nanshitou to the outskirts of Qixing Hill.
In 1953, during the construction of worker housing projects in Nanshitou by the Guangzhou Paper Mill, numerous uncoffined bones were discovered along both sides of Nanji Road, buried less than 0.5 meters deep. The bones were stacked in layers, separated by yellow soil, with a thickness of about 20 to 40 centimetres and visible from 2 meters underground. Local residents mentioned that these remains were transported from nearby punitive fields for burial. Due to the lack of other hills nearby and the overwhelming number of corpses, it was likely impractical to dig individual graves. Instead, a thin layer of soil was simply placed over the bodies each year. Construction workers treated the remains as ordinary soil and used them to fill road sections needing soil.According to witness and retired Guangzhou Paper Mill worker Cao Xiuying, at least three to four hundred bodies were observed in the area.
In the 1980s, during the construction of worker dormitories on Nanji Road by the Guangzhou Paper Mill, another three to four hundred bodies were discovered. Local residents identified them as the deceased from the Nanshitou Refugee Camp. Shen Shisheng, the former head of the Guangzhou Paper Mill's construction office, mentioned that besides the foundation pits, the exact number of bodies beneath the dormitory building was unknown. The bodies were placed in ossuaries, with each ossuary containing the remains of 2–3 individuals. There were over a hundred ossuaries in total, eventually relocated to Mashihu, Xiaolou Town, Zengcheng County.
Scepticism
According to Assistant Professor Chi Man Kwong from the History Department of Hong Kong Baptist University, the notion of Japanese conducting bacteriological experiments in Nanshitou is not surprising, given historical instances of extreme actions by the Japanese military. While some individuals have provided eyewitness testimonies and identified locations, along with some relevant documentation, there is currently a lack of sufficiently clear evidence to fully depict this event, particularly concerning the specific individuals responsible for this water supply unit and detailed information related to it.
References
Massacres of the Second Sino-Japanese War
Japanese human subject research
Anti-Chinese violence in Asia
Japanese war crimes in China
Massacres committed by Japan
Massacres of Chinese people
Mass poisoning
Crime in Guangzhou
Military history of Guangzhou
1940s in Guangzhou
Biological warfare | Nanshitou massacre | [
"Biology"
] | 2,824 | [
"Biological warfare"
] |
76,207,836 | https://en.wikipedia.org/wiki/Alexia%20F%C3%BCrnkranz-Prskawetz | Alexia Fürnkranz-Prskawetz (born 1966; published as Alexia Prskawetz) is an Austrian demographer and economist, the former director of the Vienna Institute of Demography and a director of the Wittgenstein Centre for Demography and Global Human Capital. She continues at the Vienna Institute of Demography as its deputy director, and also holds a professorship in mathematical economics at the Institute of Statistics and Mathematical Methods in Economics of TU Wien. Her research applies control theory and nonlinear dynamics to population economics, including the effects of fertility, education policy, migration, and population ageing on the workforce.
Education and career
Fürnkranz-Prskawetz was born in 1966 in Vienna. She was a student of technical mathematics applied to economics at TU Wien, earning an engineering diploma there in 1989, and completing a doctorate (Dr. techn.) in 1992. Her doctoral research also included a stint as a Fulbright Scholar at the University of Chicago.
She became a research assistant at the Vienna Institute of Demography and at the Institute for Econometrics, Operations Research and Systems Theory of TU Wien, earning a habilitation through TU Wien in 1998. This period also included postdoctoral study at the University of California, Berkeley Department of Demography from 1997 to 1998.
After heading a research group at the Max Planck Institute for Demographic Research in Rostock, Germany, from 1998 to 2003, she returned to the Vienna Institute of Demography as deputy director in 2003. In 2008 she added a second affiliation as professor of mathematical economics at TU Wien, and in 2011 she became a director of the Wittgenstein Centre for Demography and Global Human Capital. From 2012 to 2014 she headed TU Wien's Institute of Mathematical Methods in Economics, and from 2015 to 2016 she headed its Institute of Statistics and Mathematical Methods in Economics. She was director of the Vienna Institute of Demography from 2016 to 2019, and interim director again in 2013, returning to deputy director afterwards.
Recognition
Fürnkranz-Prskawetz was the 2003 recipient of the Gustav Figdor Award for Law, Social Sciences and Economics of the Austrian Academy of Sciences.
She became a corresponding member of the Austrian Academy of Sciences in 2007, and a full member in 2011. She was elected to the German National Academy of Sciences Leopoldina in 2015, and to the Academia Europaea in 2022.
References
External links
Home page at the Vienna Institute of Demography
1966 births
Living people
Austrian demographers
Austrian economists
Austrian women economists
Control theorists
TU Wien alumni
Academic staff of TU Wien
Members of Academia Europaea
Members of the Austrian Academy of Sciences
Members of the German National Academy of Sciences Leopoldina | Alexia Fürnkranz-Prskawetz | [
"Engineering"
] | 539 | [
"Control engineering",
"Control theorists"
] |
76,211,076 | https://en.wikipedia.org/wiki/Geochicas | Geochicas is a collective of feminists linked to OpenStreetMap, originally Spanish-speaking, who work for female empowerment and reducing the gender gap in the OpenStreetMap communities and communities associated with the world of free software and open data. Geochicas today has users on at least 3 continents.
The thematic areas of Geochicas are:
The fight against gender violence against women and girls
Women's health care
The visibility of feminist mobilizations
The understanding of leadership mechanisms and their brakes in the collective dimension.
History
Geochicas was born in 2016, days before the annual OpenStreetMap State of the Map LatAm 2016 conference, in São Paulo, Brazil, with the aim of discussing in a panel that would be proposed as a permanent activity, the causes and implications of the low participation of women in the construction of the map. The conclusions of this panel and forum with the total number of attendees allowed us to build the initial agenda of Geochicas, and link the first members.
The idea arose from three participants, Miriam González, Selene Yang and Céline Jacquin, who with this purpose participated in the organization of activities at SOTM in São Paulo. They organized a previous meeting between women attendees to talk about the problems they face as women in their geodate community and find out their interest in forming a network or collective. A panel was held at the close of the conference where the problematic issues of the gender gap in OpenStreetMap were raised, and the mixed group of the community present was discussed about the implications for a map so important for all types of decision-making in the world. The first lines of a work agenda were designed as conclusions of the panel and a communication channel was created integrating the interested women present. The popularity of this event led to the creation in the form of a collective focused on looking at the map of Latin America and the world, through a feminist lens.
Projects
In 2016 and 2017, the Geochicas created maps of both the oncology clinics in Nicaragua and the femicides in that country. During those same years they created visibility campaigns on Twitter with the hashtag "#MujeresMapeandoElMundo",the "International Gender Representation Survey" on OpenStreetMap.
In 2018 they created a virtual map to make visible the lack of representation of women's names on the streets of cities in Latin America and Spain.
A HOTOSM subgrant was obtained to collect field information in the Oaxaca region (Mexico) affected by the 2017 earthquakes through a journey through 20 towns, carrying out photo-mapping with Mapillary and interviewing women.
The horizontal training strategy "Training Spaces" was promoted with a series of community webinars on technology and data science training.
In 2019, an internal working group was started, based in Mexico, on femicidal violence. resulting in a rapprochement with the Geobrujas collective. For International Women's Day, a regional Editathon + Mapathon was promoted to collect data on health infrastructure for women.
A global collaborative map of the performances of "Un Violador En Tu Camino" was made inspired by the initiative of the Las Tesis collective. This proposal was extended in the mapping of mobilizations for International Women's Day in 2020.
References
Organizations for women in science and technology
Digital divide
Women in technology
OpenStreetMap | Geochicas | [
"Technology"
] | 684 | [
"Organizations for women in science and technology",
"Women in technology",
"Women in science and technology"
] |
76,212,601 | https://en.wikipedia.org/wiki/Government%20Construction%20Contracting%20Agency | Government Construction Contracting Agency (FSR) () is an independent government agency responsible for managing public works in Iceland on behalf of the government. The institution is intended to improve efficiency, cost-effectiveness, and quality in the execution of government projects. FSR is funded by financial allocations from the state and falls under the jurisdiction of the Ministry of Finance. Established in 2001, the agency is headquartered in Reykjavík.
Responsibilities
The responsibilities of FSR are defined in Act No. 84/2001 on the organization of public administration. The institution is intended to be a leading force in the field of public administration to improve efficiency, cost-effectiveness, and quality in government projects.
'Public execution' refers to the construction, maintenance, or alterations of infrastructure funded by the state to any extent, with an estimated cost to the state of at least 5 million ISK.
FSR is tasked with ensuring cost-effectiveness in the organization of public execution. To fulfill this role, the institution is required to:
provide advice and coordinate the preparation and planning of public works;
prepare and execute tenders and contracts with contractors;
handle accounting and payments for works;
take the lead in issuing guidelines for the size and quality of public infrastructure;
build and maintain a registry of state properties beneficial to ministries and government agencies in property management;
promote the development of the contractor market and increased competition;
contribute to efficiency and professional practices in connection with practical implementations.
Public execution bidding is governed by the Public Procurement Act.
Structure
FSR operates under the auspices of the Ministry of Finance and Economic Affairs, which is responsible for public works in Iceland. The institution does not have a separate board, and its director reports directly to the Minister of Finance and Economic Affairs.
The ministry responsible for the financial oversight of public works conducts initial assessments and planning. FSR then oversees the practical execution, and evaluation, and ultimately conducts performance assessments. With performance evaluations, an assessment is made of how the execution has progressed compared to plans and similar implementations.
The institution is divided into four main divisions:
The "Planning and Coordination Division" manages the maintenance and control of FSR projects in the fields of planning and coordination.
The "Execution and Evaluation Division" manages the maintenance and control of FSR projects in the fields of execution and evaluation.
The "Operations Division" handles operation-related matters of FSR, accounting, finance, financial reporting, settlements, etc.
"Support Services" is a support unit for the operations of individual divisions and reports directly to the director.
The institution operates on Part A of the budget and functions as a public institution in accordance with the Public Finance Act.
In 2024, 76 employees were registered on the FSR website.
See also
Government agencies in Iceland
References
External links
Contractor Quote
Reykjavík
Public finance
Construction organizations
Government agencies of Iceland
Organizations established in 2001
Government-owned companies of Iceland
Infrastructure in Iceland
Public administration
Government agencies established in 2001 | Government Construction Contracting Agency | [
"Engineering"
] | 579 | [
"Construction",
"Construction organizations"
] |
76,212,886 | https://en.wikipedia.org/wiki/Acromelic%20acid%20A | Acromelic acid A (ACRO A) is a toxic compound that is part of a group known as kainoids, characterized by a structure bearing a pyrrolidine dicarboxylic acid, represented by kainic acid. Acromelic acid A has the molecular formula . It has been isolated from a Japanese poisonous mushroom, Clitocybe acromelalga. Acromelic acid is responsible for the poisonous aspects of the mushroom because of its potent neuroexcitatory and neurotoxic properties. Ingestion of the Clitocybe acromelalga, causes allodynia which can continue for over a month. The systemic administration of acromelic acid A in rats results in selective loss of interneurons in the lower spinal cord, without causing neuronal damage in the hippocampus and other regions.
Structure and isoforms
Acromelic acids represent a group of compounds found in various forms. Five distinct molecules have been identified, including two isoforms designated acromelic acid A and B. Acromelic acid C-E are recognized toxic analogs. Acromelic acid A, characterized by its pyrrolidine carboxylic acid (L-proline), tricarboxylic acid, and pyridone composition, resembles kainic acid in its chemical makeup.
Acromelic acid A was the first to be isolated from Clitocybe acromelalga, leading to extensive investigation of this type. Comparative studies reveal acromelic acid B, an isoform of A, to exhibit reduced allodynia effects in mice models. Conversely, limited information exists regarding ACROs C, D, and E, though their analogous structure suggests similar functionalities to varying extents. Further research into these compounds is needed, but not without challenges; the synthesis of acromelic acid A presents difficulties for large-scale production required for comprehensive biological studies.
Synthesis
Acromelic acid A can be produced through the synthesis of L-alpha-kainic acid. However, this process involves multiple complicated steps. One way to do this, as outlined by Katsuhiro Konno et al. (1986), initiates with the successive protection of imino and carboxyl groups of L-alpha-kainic acid, followed by a reduction and silylation. Subsequently, the oxidation of the methyl group via epoxidation occurs. To form the pyridine nucleus, 1,4-addition by thiophenol, Horner-Emmons reaction, and a Pummerer reaction are necessary. Following several rearrangements, an unstable compound is obtained, which promptly cyclizes. Treatment with various compounds transforms this compound into a pyridone carboxylic acid derivative. The final steps involve the deprotection of various groups, resulting in the production of acromelic acid A. The yield of this elaborated synthesis is notably low, as expected due to the numerous synthetic steps, which in turn also hinders large-scale biological studies on acromelic acid A.
Alternatively, another synthesis route involves the condensation of L-glutamic acid with pyridones. This method, too, entails numerous steps leading to a yield of only 9%. The construction of the pyridone ring is achieved from a catechol through an oxidative cleavage recyclization strategy, akin to the previously described method. Researchers attempted a similar approach to synthesize acromelic acid B, which proved challenging but feasible.
In a more recent development, a 13-step synthesis with a yield of 36% has been described. Acromelic acids A and B were synthesized from 2,6-dichloropyridine, with the pyrrolidine ring constructed via Ni-catalyzed asymmetric conjugate addition, followed by intramolecular reductive amination. This represents an advancement over previous synthesis methods, offering a higher yield and fewer steps.
Mechanism of action
Following absorption, acromelic acid A induces abnormal behavioral symptoms in rats, and tactile allodynia in mice. Administration of this toxin causes selective degeneration specifically in lower spinal interneurons.
In the late 20th century, acromelic acid A was initially believed to act as a glutamate receptor agonist, specifically targeting AMPA receptors. This would explain the observed increase in intracellular Ca2+ concentration after administration. However, over the years, a new type of non-NMDA receptor was thought to be the target of acromelic acid A, as the observed effects couldn't completely be explained by AMPA binding. This idea was established through comparative studies with kainic acid, another glutamate receptor agonist. This revealed remarkable differences in behavioral and pathological effects.
Therefore, the proposed mechanism suggests binding of acromelic acid A to a (yet unidentified) non-NMDA receptor. Binding to the target receptor leads to depolarization of the postsynaptic cell. This depolarization subsequently activates NMDA receptors, which in turn become permeable for Ca2+. The increase in intracellular Ca2+ concentration triggers a cascade of downstream signaling events, including activation of various intracellular enzymes. Consequently, neuronal damage and sustained neuronal excitability, particularly in spinal cord neurons, occur
Although researchers know the resulting pathological symptoms and some molecular conditions after administration of acromelic acid A, they have still not been able to unravel the exact mechanism of action of this neurotoxic compound. Therefore, further investigation into the mechanism of action of acromelic acid A is required to better understand the toxic effects.
Toxicity
Research has revealed that the lethal dose () ranges between 5 and 5.5 mg/kg in rats, when acromelic acid A administered intravenously.
Effects on rats
Multiple studies were performed in which rats were injected with acromelic acid A intravenously. Kwak et al. (1991) conducted experiments involving the injection of both 2 mg/kg and the lethal dose (5 mg/kg) of acromelic acid A in rats. The results demonstrated a series of behavioral changes.
30 minutes after injection: All rats began to bite and moved their tails like snails. Their hindlimbs became gradually extended and their back slowly bent forwards, which led them to occasional falls. Further, rats suffered from attacks of intermittent hindlimb cramp, which became tonic over time.
1 hour after injection: Rats were seized by tonic cloning convulsions. The Rats which got the lethal dose died during these seizures. The surviving rats developed complete flaccid paraplegia which carried on for 2 hours.
Days after injection: Rats developed paraparesis of severe spasticity. They were able to move using their forelimbs.
Effects on mice
Intrathecal administration of acromelic acid A provoked tactile allodynia in mice. At an extremely low dose of 1 fg/mouse allodynia was already provoked and persisted over a month. Furthermore, at a higher dose of 500 ng/kg, injection of acromelic acid A induced strong spontaneous agitation, scratching, jumping and tonic convulsion and caused death within 15 min.
Effects on humans
The effects of acromelic acid A on humans have not been studied yet. However, after accidental ingestion of Clitocybe acromelalga, violent pain and marked reddish edema in hands and feet were observed after several days and continued for a month. However, there is no direct evidence these symptoms were caused by acromelic acid A. Findings from experiments in rats and mice suggest a potential association between acromelic acid A and the observed symptoms.
References
Pyrrolidines
Carboxylic acids
Pyridines | Acromelic acid A | [
"Chemistry"
] | 1,645 | [
"Carboxylic acids",
"Functional groups"
] |
76,212,889 | https://en.wikipedia.org/wiki/Microplastics%20and%20human%20health | Microplastics effects on human health are of growing concern and an area of research. The tiny particles known as microplastics (MPs), have been found in various environmental and biological matrices, including air, water, food, and human tissues. Microplastics, defined as plastic fragments smaller than 5 mm, and even smaller particles such as nanoplastics (NP), particles smaller than 1000 nm in diameter (0.001 mm or 1 μm), have raised concerns impacting human health. The pervasive presence of plastics in our environment has raised concerns about their long-term impacts on human health. While visible pollution caused by larger plastic items is well-documented, the hidden threat posed by nanoplastics remains under-explored. These particles originate from the degradation of larger plastics and are now found in various environmental matrices, including water, soil, and air. Given their minute size, nanoplastics can penetrate biological barriers and accumulate in human tissues, potentially leading to adverse health effects.
Plastics continue to accumulate in landfills and oceans, leading to pollution that negatively impacts both human and animal health. Notably, microplastics and nanoplastics are now ubiquitous, infiltrating our food chain and water supplies. Studies indicate that humans ingest significant amounts of microplastics daily through food, especially seafood and inhalation, with estimates ranging from 39,000 to 52,000 particles per person annually Additionally, the presence of microplastics in human feces suggests widespread exposure and absorption. In scientific literature, combined microplastics and nanoplastics are referred to as MNPs or NMPs, or NMPPs for nano-and microplastic particles.
Understanding the sources and health effects of nanoplastics is crucial for developing effective public health policies. As plastics are an integral part of modern life, balancing their benefits with the associated health risks is essential. This research aims to provide evidence-based recommendations to mitigate the adverse health effects of nanoplastics, thereby informing future regulatory and policy decisions. The increasing presence of nanoplastics in the environment has raised concerns about their potential impacts on human health. Research has shown that nanoplastics can penetrate biological barriers, induce toxicity, and accumulate in organs, leading to various health issues . Nanoplastics have been found in drinking water, food, and air, making human exposure ubiquitous.
Routes of exposure and bioaccumulation
The major pathways of human exposure to micro- and nanoplastics (MNPs) are ingestion, inhalation, and dermal contact, with bioaccumulation varying based on particle size, composition, and physicochemical characteristics. Research suggests that MNPs above 150 μm typically remain confined to tissues and do not enter systemic circulation, whereas particles below 200 nm can breach cellular and tissue barriers, potentially reaching the bloodstream and other organs. This diversity in bioaccumulation pathways underscores the widespread yet nuanced risks of MNP exposure to human health.
Ingestion
Ingestion is one of the primary pathways of MNP exposure due to the omnipresence of these particles in food, beverages, and drinking water. Studies show that MNPs are detected in a variety of consumables, including drinking water, beer, honey, sugar, table salt, and even airborne particles that settle on food. Indirect ingestion includes toothpaste, face wash, scrubs, and soap and enter systemic circulation.
Marine products are particularly concerning sources of ingestion-related exposure due to the accumulation of MNPs in aquatic environments. Fish, bivalves, and other seafood are frequently contaminated with MNPs ingested through water and food, and humans consuming these animals are thus directly exposed to microplastic particles embedded in tissue. The entire soft tissue of bivalves, for instance, is eaten by humans, which increases the direct transfer of MNPs. In a study along the Mediterranean coast of Turkey, 1,822 microplastic particles were extracted from the stomachs and intestines of 1,337 fish specimens, with fibers accounting for 70% of these particles.
Contamination is further compounded by plastic packaging and storage materials, which can leach MNPs over time, leading to additional ingestion from common foods and drinks. Fecal sample analyses estimate a daily intake of approximately 203–332 MNP particles, translating to an annual ingestion rate of around 39,000–52,000 particles. This suggests that daily MNP exposure from food and drink may be substantial, with significant implications for gastrointestinal and systemic health.
Maternal exposure
Maternal transfer of MNPs represents an emerging exposure route that affects infants directly. Recent studies have shown the presence of microplastics in breast milk, often leading to exposures in very young children. While it has already been established that chemicals <ref>Calabrese, Edward J. (March 1992). "Human Breast Milk Contamination in the United States and Canada by Chlorinated Hydrocarbon Insecticides and Industrial Pollutants: Current Status". Journal of the American College of Toxicology. 1 (3): 91–98. doi:10.3109/10915818209018020. ISSN 0730-0913. </ref> such as flame retardants Brilliant, LawrenceB.; Van Amburg, George; Isbister, John; Humphrey, Harold; Wilcox, Kenneth; Eyster, Janet; Bloomer, ArthurW.; Price, Harold (September 1978). "Breast-Milk Monitoring to Measure Michigan's Contamination with Polybrominated Biphenyls". The Lancet. 312 (8091): 643–646. doi:10.1016/s0140-6736(78)92758-7. hdl:2027.42/22528. ISSN 0140-6736. PMID 80575. and pesticides have been detected in breast milk, knowledge about microplastics is limited in comparison. A 2022 study detected microplastic particles smaller than five millimeters in 75% of analyzed breast milk samples, raising concerns about infant exposure during critical developmental windows.Kopatz, V., Wen, K., Kovács, T., Keimowitz, A. S., Pichler, V., Widder, J., ... & Kenner, L. (2023). Micro-and nanoplastics breach the blood–brain barrier (BBB): Biomolecular corona's role revealed. Nanomaterials, 13(8), 1404.
Exposure during developmental stages can lead to long lasting developmental defects or other issues later in life. While these detected levels were not above the currently established thresholds for unsafe levels, they show another possible route for microplastic ingestion. For some native population in north Canada and people who live near industrial factories, it is sometimes suggested by pediatricians that mothers not nurse their children, over fear of ingestion of microplastics and other potentially harmful chemicals. It has been suggested that mothers should directly breast feed their children instead of from a bottle. Studies have shown that pumping milk, freezing it in plastic bags, then subsequently heating it up will increase the contamination of microplastics in the milk. Similar results have been seen from heating plastic reusable food containers in a microwave, showing the release of both microplastics and nanoplastics. It has been suggested that mothers try to avoid ingesting microplastics themselves, to try and avoid passing them onto their children through breastfeeding. Studies have shown that drinking water from plastic bottles has significantly greater detectable plastic content than tap water.
These findings suggest that breastfeeding may inadvertently expose infants to endocrine-disrupting plastics, which could have lasting effects on growth and development. To mitigate these risks, pediatricians recommend reducing the use of plastic bottles and avoiding the heating or freezing of breast milk in plastic containers, as temperature fluctuations can increase MNP leaching.
Dermal contact
Though less frequently examined, dermal exposure to MNPs occurs through contact with contaminated media like soil, water, and personal care products, including facial and body scrubs containing MNPs as exfoliants.Dris, Rachid; Gasperi, Johnny; Saad, Mohamed; Mirande, Cécile; Tassin, Bruno (March 2016). "Synthetic fibers in atmospheric fallout: A source of microplastics in the environment?". Marine Pollution Bulletin. 104 (1–2): 290–293. Bibcode:2016MarPB.104..290D. doi:10.1016/j.marpolbul.2016.01.006. PMID 26787549. Although the skin generally acts as a barrier, conditions such as skin lesions or high exposure environments may allow for enhanced absorption of MNPs, particularly nanoparticles, which can penetrate the stratum corneum. Studies on dermal exposure highlight the potential for these particles to enter systemic circulation, especially if the skin barrier is disrupted by wounds or conditions that increase permeability, like pores such as sweat glands and hair follicles
Inhalation
Inhalation is a critical but understudied route of MNP exposure, with airborne MNPs originating from urban dust, synthetic fibers from textiles, rubber tires, and household plastic items. These airborne particles may become suspended in the air due to wave action in aquatic environments or the spread of wastewater treatment sludge on agricultural fields. Once inhaled, these particles may lodge in the lungs or, through mucociliary clearance, be ingested and enter the digestive system.Murashov, Vladimir; Geraci, Charles L.; Schulte, Paul A.; Howard, John (2021-11-02). "Nano- and microplastics in the workplace". Journal of Occupational and Environmental Hygiene. 18 (10–11): 489–494. doi:10.1080/15459624.2021.1976413. ISSN 1545-9624. PMC 10020928. PMID 34478348. Airborne microplastics have been detected in urban atmospheres, with reports showing a fallout of 29–280 particles per square meter per day on an urban rooftop, underscoring the potential for routine exposure. Annual inhalation exposure rates are estimated at around 39,000–52,000 microplastic particles, with studies highlighting the significant contributions from synthetic textiles and urban dust sources.
These findings collectively suggest that MNPs may accumulate in multiple organ systems depending on the exposure route, potentially leading to long-term health consequences as their presence in human tissues becomes more pervasive over time.
Occupational exposure
Incidental generation of MNPs is mechanical or environmental degradation or industrial processes such as plastic manufacturing (heating and chemical condensation) and intentional generation of MNPs occur during 3D printing.
The main route of workplace exposure is acute inhalation. Workplace exposure can be high concentration and lasting the duration of a shift and thus short-term whereas exposure outside of work is at low concentration and long-term. The concentration of worker exposure is orders of magnitude higher than the general population'' (e.g., 4×1010 particles per m3 from extrusion 3D printers versus 50 particles per m3 in the general environment).
High chronic exposure to aerosolized MNPs occur in: the synthetic textile industry, the flocking industry, and the plastics industry consisting of the Vinyl Chloride supplier and the Polyvinyl Chloride manufacturer.
Manufacturing and processing of plastic
3D printing. Additive Manufacturing such as commercial extrusion printing and multi-jet fusion printing with thermoplastics and resin emit MNPs and organic vapors (Volatile Organic Compounds) into the ambient workplace air. There is emerging evidence of allergic, respiratory, and cardiovascular adverse effects from 3D printing. For extrusion printing Acrylonitrile butadiene styrene (ABS) filaments emit more MNPs than Polylactic acid (PLA) filaments.
Nylon flocking is the process of applying, cutting, sanding and machining of nylon polymers on surfaces where dust emission peaks during air blowing flocked surfaces.
Coating utensils and cookware: polytetrafluoroethylene, and high energy or heat processing of plastic products (Bello et al. 2010; Walter et al. 2015).
Dust generation occurs in a wide range of settings from composite material machining, drilling, hand-held grinding, and sanding of nanotube-containing composites, and sanding of dental composites, and cutting PVC piping and plastics.
PVC and plastic production produces PVC dust with mortality confirmed among vinyl and polyvinyl chloride workers after reanalysis of data and coronary artery disease and cancer death among vinyl chloride exposed workers
Rubber chemical manufacturing impacting mortality among these workers.
Environmental and mechanical degradation of plastic
Carpet and synthetic fibers: indoor air contains high concentrations of degraded synthetic fibers with potential exposure to office workers and custodial staff; settled dust is ingested by adults, and particularly children.
Wastewater management, recycling facilities, and landfills: plastic goods undergo environmental (weathering) and mechanical degradation and wastewater management and recycling facilities and landfills serve as a reservoirs of particulates workers may potentially be exposed to.
Medical plastic
Face masks and respirators: globally up to 7 billion facemasks which amounts to 21,000 tons of synthetic polymer, were estimated to be used daily during the COVID-19 pandemic increasing plastic demand and waste. It is yet unknown if respirable NMP debris on the surface of facemasks poses adverse health effects.
Medical plastics include a wide range of products from bags to pharmaceutical containers that leach and expose patients and healthcare workers to MNPs. Further research is needed to assess toxicology and medical significance of MNPs from medical plastics.
Potential health risks
The potential health impacts of microplastics vary based on factors, such as their particle sizes, shape, exposure time, chemical composition (enriched with heavy metals, polycyclic aromatic hydrocarbons (PAHs), etc.), surface properties, and associated contaminants.
Experimental and observational studies in mammals have shown that microplastics and nanoplastics exposure have the following adverse effects:
On the cellular level
Inflammation
Oxidative stress
Genotoxicity
Cytotoxicity
By systems
Cardiovascular
Respiratory
Inflammation in the lungs from inhalation
Disruption of hypothalamic-pituitary axis (HPA), including the Hypothalamic-pituitary-thyroid, Hypothalamic-pituitary-adrenal, Hypothalamic-pituitary-testicular and Hypothalamic-pituitary-ovarian axis
Reproductive toxicity, decreased reproductive health, decreased sperm quality
Developmental abnormalities
Immunotoxicity
Endocrine disruption
Neurotoxicity
Metabolic disturbances
Disrupted gut-liver axis resulting in increased risk of insulin resistance
disrupted hormone function, potentially contributing to weight gain.
Epidemiological studies
Despite growing concern and evidence, most epidemiologic studies have focused on characterizing exposures. Epidemiological studies directly linking microplastics to adverse health effects in humans remain yet limited and research is ongoing to determine the full extent of potential harm caused by microplastics and their long-term impact on human health.
Prevalence
Microplastics have been found in blood.
Mitigating inhalation exposure to MNPs
As April 2024, there is no established NIOSH Recommended Exposure Limit (REL) for MNPs due to limited data on exposure levels to adverse health effects, the absence of standardization to characterize the heterogeneity of MNPs by chemical composition and morphology, and difficulty in measuring airborne MNPs. And thus, safety measures focus on the hierarchy of controls for nanomaterials with good industrial hygiene to implement source emission control with local exhaust ventilation, air filtration, and nonventilating engineering controls such as substitution with less hazardous materials, administrative controls, Personal Protective Equipment (PPE) for skin and respiratory protection.
Research from the U.S. National Institute of Occupational Safety and Health (NIOSH) Nanotechnology Research Center (NTRC) show local exhaust ventilation and High Efficiency Particulate Air (HEPA) filtration to be effective mitigation to theoretically filter 99.97% of nanoparticles down to 0.3 microns.
See also
Bisphenol A (BPA) and exposure to humans
Polyvinyl chloride and health
Microplastic remediation
References
Clothing and the environment
Plastics and the environment
Environmental impact of products
Water pollution
Health effects by subject | Microplastics and human health | [
"Chemistry",
"Environmental_science"
] | 3,467 | [
"Water pollution"
] |
76,212,894 | https://en.wikipedia.org/wiki/D-peptide | A D-peptide is a small sequence of D-amino acids. Since ribosomes are specific to L-amino acids, D-peptides rarely occur naturally in organisms and are not easily digested or degraded. D-peptide peptidomimetics are D-peptides designed to mimic natural L-peptides that commonly have therapeutic properties. A peptide with secondary structure cannot be mimicked by its retro-inverse, as linking in the reverse order breaks many backbone interactions essential for the secondary structure. An approach to mimicking these peptides is by searching for similar (sidechain) structures in a mirrored copy of the Protein Data Bank for the structured elements, and then linking the sections by retro-inversed versions of the loops found in the original protein.
When placed in a nonchiral solvent like water, D-peptides, as well as the larger polypeptide D-proteins, have similar but mirrored properties to the L-peptides and L-proteins with identical sequences. If an L-protein does not require a chaperone or a structural cofactor to fold, its D-enantiomer protein should have a mirror image conformation with respect to the L-protein (Figure 2). A D-enzyme should act on substrates of reverse chirality compared to the L-enzyme with the same sequence. Similarly, if an L-peptide binds to an L-protein, their D-peptide and D-protein counterparts should bind together in a mirrored way.
D-peptides also have properties that make them attractive as drugs. D-peptides are less susceptible to be degraded in the stomach or inside cells by proteolysis. D-peptide drugs can, therefore, be taken orally and are effective for a longer period of time. D-peptides are easy to synthesize when compared to many other drugs. In some cases, D-peptides can have a low immunogenic response.
Ret design
An L-peptide has three analogue sequences (Figure 3) built from L and D amino acids: the D-enantiomer or inverso-peptide with the same sequence, but composed of D-amino acids and a mirror conformation; the retro-peptide, consisting of the same sequence of L amino acids but in reverse order; and the retro-inverso or D-retro-enantiomer peptide, consisting of D-amino acids in the reversed sequence.
While the L-peptide and its D-enantiomer are mirror structures of each other, the L-retro-peptide is the mirror image of the D-retro-inverso-peptide. On the other hand, the L-peptide and the D-retro-inverso-peptide share a similar arrangement of side-chains, although their carboxyl and amino groups point in opposing directions. For small peptides that do not depend on a secondary structure for binding, an L-peptide and its D-retro-inverso-peptide is likely to have a similar binding affinity with a target L-protein.
Mirror-image phage display
Phage display is a technique to screen large libraries of peptides for binding to a target protein. In phage display, the DNA sequence that codes the potential drug-peptide is fused to the gene of the protein coat of bacteriophages and introduced into a vector. Diversity can be introduced to the peptide by mutagenesis. The protein coats peptides are then expressed and purified, and applied to a surface of immobilized protein targets. The surface is then washed away to remove non-binding peptides, while the remaining binding peptides are eluted.
Mirror-image phage display is a similar method that can be used to screen large libraries of D-peptides that bind to target L-proteins. More precisely, since D-peptides can not be expressed in bacteriophages, mirror-image phage display screens L-peptides that bind to immobilized D-proteins that are previously chemically synthesized. Because of the mirror properties of D-peptides, the D-enantiomer of an L-peptide that binds to a D-protein will bind to the L-protein.
Mirror-image phage display, however, has two disadvantages when compared to phage display. Target D-proteins must be chemically synthesized, which is normally an expensive and time-consuming process. Also, the target protein must not require a cofactor or a chaperone to fold, otherwise the chemically synthesized D-protein will not fold to the target, mirror structure.
References
Peptides | D-peptide | [
"Chemistry"
] | 953 | [
"Biomolecules by chemical classification",
"Peptides",
"Molecular biology"
] |
76,213,778 | https://en.wikipedia.org/wiki/Aarti%20Holla-Maini | Aarti Holla-Maini is a British lawyer, economist and space expert. Since 2023, she has been Director of United Nations Office for Outer Space Affairs (UNOOSA).
Life
Holla-Maini studied German law at King's College in London from 1988 to 1992 with a foreign part at the University of Passau (1990–1991) and graduated with a bachelor's degree and LL.B. She completed her Legal Practice Course at the University of Law from 1992 to 1993.
She completed a master's degree in business administration at the École des hautes études commerciales in Paris (HEC) from 1995 to 1997, spending the first year of her studies as part of an exchange program at the New York University Stern School of Business. In 2021 she completed an Executive Space course at the International Space University in Alsace.
Holla-Maini worked as a business development manager at Airbus Defense and Space from 1997 to 2004 in Munich and Brussels. From 2004 to 2023 she was a consultant and Secretary General of the Global Satellite Operators Association. She was replaced by Isabelle Mauro.
She took the leadership of an idea called UNOOSA Space Bridge which was launched at the start of 2024. The idea was to increase communication between areas of global interest using exchange programmes and other techniques to break down information silos.
On 26 June 2023 Holla-Maini was appointed director of the UN Office for Space Affairs in Vienna by UN Secretary-General António Guterres. She followed the Italian physicist Simonetta Di Pippo and an interim appointee. Holla-Maini highlighted the problem of space debris. It is estimated that there is 9,000 tonnes of debris in orbits at speeds of around 15,000 mph. The amount is increasing and there is an increased chance of collisions creating more bits. Holla-Maini predicted that it would take some time to agree international rules, but the UN had issued guidelines in 2019 and these could be the basis of national policies until then.
On 21 November 2024, she appeared in a video featuring Ukrainian youtuber based in London Max Klymenko at an airport in Azerbaijan.
Holla-Maini speaks English, French, German and Punjabi.
Personal life
She has three children.
References
Living people
Alumni of King's College London
Alumni of the University of Law
British women lawyers
Space law
United Nations officials
Year of birth missing (living people) | Aarti Holla-Maini | [
"Astronomy"
] | 489 | [
"Space law",
"Outer space"
] |
76,213,802 | https://en.wikipedia.org/wiki/Fimea | The Finnish Medicines Agency (Fimea; ) is a central agency under the Ministry of Social Affairs and Health that regulates medicines, medical devices, blood and tissue products, biobanks, and develops the pharmaceutical industry. Fimea was established in 2009, succeeding the National Agency for Medicines. Its predecessor, the National Agency for Medicines, had been operational since 1994.
Responsibilities
Fimea's tasks and objectives are based on national and EU legislation, government programs, the strategy of the Ministry of Social Affairs and Health, and performance and resource management. The agency's task areas include pharmaceutical licensing and supervision tasks, research and development, and the production and dissemination of pharmaceutical information to improve the effectiveness of pharmaceutical care and treatment. Fimea is part of the European medicines regulatory network and is oriented towards international cooperation.
Fimea acts as the licensing and supervisory authority for human or veterinary medicines, blood and tissue products, and pharmaceutical operators. Fimea also monitors the compliance of medical devices and pharmaceutical operators in Finland. Fimea is also responsible for coordinating national pharmaceutical development, research tasks, and evaluating pharmaceutical treatments. Fimea collects and evaluates clinical information on pharmaceutical treatments and develops treatment practices through education and information dissemination.
Fimea's operations are funded by revenue from fee-based activities and state appropriations.
Operations
Eija Pelkonen serves as Fimea's Director-General. Fimea's organizational structure was reformed in 2022 and consists of three functional areas: Marketing Authorizations, Supervision and Availability, and Safety and Effectiveness. In addition, the functional areas are supported by Shared Services, Communication Services, and Information and Development Services.
Fimea's main office is located in Kuopio. Fimea also has offices in Helsinki, Turku, Tampere, and Oulu.
References
Government agencies of Finland
National agencies for drug regulation | Fimea | [
"Chemistry"
] | 383 | [
"National agencies for drug regulation",
"Drug safety"
] |
76,215,026 | https://en.wikipedia.org/wiki/Einstein%E2%80%93Oppenheimer%20relationship | Albert Einstein and J. Robert Oppenheimer were twentieth century physicists who made pioneering contributions to physics. From 1947 to 1955 they had been colleagues at the Institute for Advanced Study (IAS). Belonging to different generations, Einstein and Oppenheimer became representative figures for the relationship between "science and power", as well as for "contemplation and utility" in science.
Overview
In 1919, after the successful verification of the phenomenon of light from faraway stars gravitationally bending near the sun — as predicted earlier by Einstein's theory of gravity — became an observable fact, Albert Einstein was acclaimed as “the most revolutionary innovator in physics” since Isaac Newton. J. Robert Oppenheimer, called the American physics community's "boy-wonder" in the 1930s, became a popular figure from 1945 onwards after overseeing the first ever successful test of nuclear weapons.
Both Einstein and Oppenheimer were born into nonobservant Jewish families.
Belonging to different generations, Einstein (1879–1955) and Oppenheimer (1904–1967), with the full development of quantum mechanics by 1925 marking a delineation, represented the shifted approach in being either a theoretical physicist or an experimental physicist since the mid-1920s when being both became rare due to the division of labor.
Einstein and Oppenheimer, who incorporated different modes of approach for their achievements, became emblematic for the relationship between "science and power", as well as for "contemplation and utility" in science. When in 1945 the first ever nuclear weapons were successfully tested, Oppenheimer was acknowledged for bringing forth to the world the astounding "instrumental power of science". Einstein, after facing criticism for having "participated" in the creation of the atomic bomb, answered in 1950 that, when he contemplated on the relationship between mass and energy in 1905, he had no idea that it could have been used for military purposes in anyway, and maintained that he had always been a "convinced pacifist".
While Einstein engaged in the pursuit of what he called as "Unity" in the complex phenomena of the Universe, Oppenheimer engaged in the establishment of an "Unified" framework at the Institute for Advanced Study, which would comprise all the academic disciplines of knowledge that can be pursued. Einstein was markedly individualistic in his approach to physics. He had only few students, and was disinterested if not adversarial in his relation with formal institutions and politics. Oppenheimer was more collaborative and embraced collective scientific work. He had been a better successful teacher and more immersed in political and institutional realms. Oppenheimer emerged as a powerful political 'insider', a role that Einstein never embraced but instead wondered why Oppenheimer desired such power. Despite their differences in stances, both Oppenheimer and Einstein were regarded as "deeply suspicious" figures by the authorities, specifically by J. Edgar Hoover.
With the advent of modern physics in the twentieth century changing the world radically, both Einstein and Oppenheimer grappled with metaphysics that can provide an ethical framework for human actions. Einstein turned to the philosophical works of Spinoza and Schopenhauer, along with an attachment to the European enlightenment heritage. Oppenheimer became engrossed in the eastern philosophy, with particular interest in the Bhagavad Gita, and an affinity with the American philosophical tradition of pragmatism.
Association with each other
Oppenheimer met Einstein for the first time in January 1932 when the latter visited Caltech as part of his round-the-world trip during 1931-32.
In 1939, Einstein published a paper that argued against the existence of Black holes. Einstein used his own general theory of relativity to arrive at this conclusion. A few months after Einstein rejected the existence of Black holes, Oppenheimer and his student Hartland Snyder published a paper that revealed, for the first time, using Einstein's general theory of relativity, how Black holes would form. Though Oppenheimer and Einstein later met, there's no record of them having discussed Black holes.
When in 1939, the general public became aware of the Einstein–Szilard letter that urged the US government to initiate the Manhattan project, for the development of nuclear weapons, Einstein was credited for foreseeing the destructive power of the atom with his mass–energy equivalence formula. Einstein played an active role in the development of US nuclear weapons by being an advisor to the research that ensued; this was in contrast to the common belief that his role was limited to only signing a letter. During this time, the public linked Einstein with Oppenheimer, who then happened to be the scientific director of the Manhattan project.
In 1945, when Oppenheimer and Pauli were being considered for a professorial position at an institute, Einstein and Hermann Weyl wrote a letter that recommended Pauli over Oppenheimer.
After the end of World War II, both Einstein and Oppenheimer lived and worked in Princeton at the Institute for Advanced Study, Einstein became a professor there while Oppenheimer its director and a professor of physics from 1947 to 1966. They had their offices down the hall from each other. Einstein and Oppenheimer became colleagues and conversed with each other occasionally. They saw each other socially, with Einstein once attending dinner at the Oppenheimers in 1948. At the Institute, Oppenheimer considered general relativity to be an area of physics that wouldn't be of much benefit to the efforts of physicists, partly due to lack of observational data and due to conceptual and technical difficulties. He actively prohibited people from taking up these problems at the institute. Furthermore he forbade Institute members from having contacts with Einstein. For one of Einstein's birthdays, Oppenheimer gifted him a new FM radio and had an antenna installed on his house so that he may listen to New York Philharmonic concerts from Manhattan, about 50 miles away from Princeton. Oppenheimer did not provide an article to the July 1949 issue of Reviews of Modern Physics, which was dedicated to the seventieth birthday of Einstein.
In October 1954, when an honorary doctorate was to be conferred to Einstein at Princeton, Oppenheimer made himself unavailable at the last moment (despite being "begged" to attend the event); he informed the convocation committee that he had to be out of town on the day of convocation. Earlier, in May 1954 when the Emergency Civil Liberties Committee decided to honour Einstein on his seventy-fifth birthday, the American Committee for Cultural Freedom, concerned about the Communist ties of the honouring committee requested Oppenheimer to stop Einstein from attending the event lest it may cause people to associate Judaism with Communism, and think of scientists as naive about politics. Oppenheimer, who was then busy with his security clearance hearings, persuaded Einstein to dissociate with the honouring committee.
Views about each other
In January 1935, Oppenheimer visited Princeton University as a visiting faculty member on an invitation. After staying there and interacting with Einstein, Oppenheimer wrote to his brother Frank Oppenheimer in a letter thus, "Princeton is a madhouse: its solipsistic luminaries shining in separate & helpless desolation. Einstein is completely cuckoo. ... I could be of absolutely no use at such a place, but it took a lot of conversation & arm waving to get Weyl to take a no”. Oppenheimer's initial harsh assessment was attributed to the fact that he found Einstein highly skeptical about the quantum field theory. Einstein never accepted the quantum theory; in 1945 he said: "The quantum theory is without a doubt a useful theory, but it does not reach to the bottom of things. I never believed that it constitutes the true conception of nature". Oppenheimer also noted that Einstein became very much a loner in his working style.
After the death of Einstein in April 1955, in a public eulogy Oppenheimer wrote that "physicists lost their greatest colleague". He noted that of all the great accomplishments in Physics, the theory of general relativity is the work of one man, and it would have remained undiscovered for a long time had it not been for the work of Einstein. He ascertained that the public image of Einstein as a simple and kindhearted man “with warm humor,... wholly without pretense” was indeed right, and remembered what Einstein once said to him before his death, "You know, when it once has been given to a man to do something sensible, afterwards life is a little strange." Oppenheimer wrote that it was given to Einstein to do "something reasonable". He stated that general theory of relativity is "perhaps the single greatest theoretical synthesis in the whole of science". Oppenheimer wrote that more than anything, the one special quality, that made Einstein unique was “his faith that there exists in the natural world an order and a harmony and that this may be apprehended by the mind of man”, and that Einstein had given not just an evidence of that faith, but also its heritage.
Oppenheimer was less graceful about Einstein in private. He said Einstein had no interest in or did not understand modern physics and wasted his time in trying to unify gravity and electromagnetism. He stated that Einstein's methods in his final years had in "a certain sense failed him". Einstein in his last twenty-five years of life focused solely on working out the unified field theory without considering its reliability nor questioning his own approach. This led him to lose connections with the wider physics community. Einstein's urge to find unity had been constant throughout his life. In 1900, while still a student at ETH, he wrote in a letter to his friend Marcel Grossmann that, "It is a glorious feeling to recognize the unity of a complex of phenomena, which appear to direct sense perceptions as quite distinct things." In 1932, when questioned about his goal of work, Einstein replied, "The real goal of my research has always been the simplification and unification of the system of theoretical physics. I attained this goal satisfactorily for macroscopic phenomena, but not for the phenomena of quanta and atomic structure." And added, "I believe that despite considerable success, the modern quantum theory is still far from a satisfactory solution of the latter group of problems." Einstein was never convinced with quantum field theory, which Oppenheimer advocated. Oppenheimer noted that Einstein tried in vain to prove the existence of inconsistencies in quantum field theory, but there were none. In the 1960s Oppenheimer became skeptical about Einstein's general theory of relativity as the correct theory of gravitation. He thought Brans–Dicke theory to be a better theory. Oppenheimer also complained that Einstein did not leave any papers to the institute (IAS) in his will despite the support he received from it for twenty-five years. All of Einstein's papers went to Israel.
In December 1965, Oppenheimer visited Paris on an invitation from UNESCO to speak at the tenth anniversary of Einstein's death. He spoke on the first day of the commemoration as he had known Einstein for more than thirty years and at the IAS, they "were close colleagues and something of friends". Oppenheimer made his critical views of Einstein public there. He also praised Einstein for his stand against violence and described his attitude towards humanity by the Sanskrit word "Ahimsa". The speech received considerable media attention, New York Times reported the story headlined “Oppenheimer View of Einstein Warm But Not Uncritical”. After the speech, as part of an effort to amend any misunderstandings, in an interview with the French magazine L'Express, Oppenheimer said, "During all the end of his life, Einstein did no good. He worked all alone with an assistant who was there to correct his calculations... He turned his back on experiments, he even tried to rid himself of the facts that he himself had contributed to establish ... He wanted to realize the unity of knowledge. At all cost. In our days, this is impossible." But nevertheless, Oppenheimer said he was "convinced that still today, as in Einstein’s time, a solitary researcher can effect a startling discovery. He will only need more strength of character". The interviewer concluded asking Oppenheimer if he had any longing or nostalgia, to which he replied "Of course, I would have liked to be the young Einstein. This goes without saying."
Einstein appreciated Oppenheimer for his role in the drafting and advocacy of the Acheson–Lilienthal Report, and for his subsequent work to contain the nuclear arms race between the United States and Soviet Union.
At the IAS, Einstein acquired profound respect for Oppenheimer on his administration skills, and described him as an “unusually capable man of many sided education”.
In popular culture
A semifictional account of the relationship between Albert Einstein and J. Robert Oppenheimer was portrayed in the feature film Oppenheimer directed by Christopher Nolan.
Notes
See also
Einstein versus Oppenheimer
References
Citations
Sources
Quantum physicists
Theory of relativity
History of physics | Einstein–Oppenheimer relationship | [
"Physics"
] | 2,684 | [
"Quantum physicists",
"Quantum mechanics",
"Theory of relativity"
] |
76,216,842 | https://en.wikipedia.org/wiki/Data%20physicalization | A data physicalization (or simply physicalization) is a physical artefact whose geometry or material properties encode data. It has the main goals to engage people and to communicate data using computer-supported physical data representations.
History
Before the invention of computers and digital devices, the application of data physicalization already existed in ancient artifacts as a medium to represent abstract information. One example is Blombo ocher plaque which is estimated to be 70000 – 80000 years old. The geometric and iconographic shapes engraved at the surface of the artifact demonstrated the cognitive complexity of ancient humans. Moreover, since such representations were deliberately made and crafted, the evidences suggest that the geometric presentation of information is a popular methodology in the context of society. Although researchers still cannot decipher the specific type of information encoded in the artifact, there are several proposed interpretations. For example, the potential functions of the artifact are divided into four categories, categorized as "numerical", "functional", "cognitive", and "social". Later, at around 35,000 B.C, another artifact, the Lebombo bone, emerged and the encoded information became easier to read. There are around 29 distinct notches carved on the baboon fibula. It is estimated that the number of notches is closely related to the number of lunar cycles. Moreover, this early counting system was also regarded as the birth of calculation.
Right before the invention of writing, the clay token system was spread across ancient Mesopotamia. When the buyers and sellers want to make a trade, they prepare a set of tokens and seal them inside the clay envelope after impressing the shape on the surface. Such physical entity was widely used in trading, administrative documents, and agricultural settlement. Moreover, the token system is evidence of the early counting system. Each shape corresponds to a physical meaning such as the representation of "sheep", forming a one-to-one mapping relationship. The significance of the token is it uses physical shape to encode numerical information and it is regarded as the precursor of the early writing system. The logical reason is the two-dimension symbol would record the same information as the impression created by the clay token.
From 3000 BCE to the 17th century, a more complex visual encoding, Quipus, was developed and widely used in Andean South America. Knotted strings unrelated to quipu have also been used to record information by the ancient Chinese, Tibetans and Japanese. The ancient Inca empire used it for military and taxation purposes. The Base-10 logical-numerical system can record information based on the relative distance of knots, the color of the knots, and the type of knots. Due to the texture (cotton) of Quipus, very few of them survive. By analyzing those remaining artifacts, Erland Nordenskiöld proposed that Quipus is the only writing system used by Inca, and the information encoding technique is sophisticated and distinctive.
The idea of data physicalization become popular since the 17th century in which architects and engineers widely used such methods in civil engineering and city management. For example, from 1663 to 1867, Plan-relief model was used to visualize French territorial structure and important military units such as citadels and walled cities. Therefore, one of the functions of the Plan-relief model was to plan defense or offense. It is worth noting that the model can be categorized as a military technology and it did not encode any abstract information. The tradition of using tangible models to represent buildings and architectures still remains today.
One of the contemporary examples of data physicalization is the Galton board designed by Francis Galton who promoted the concept of Regression toward the mean. The Galton board, a very useful tool in approximating the Gaussian law of errors, consists of evenly spaced nails and vertical slats at the bottom of the board. After a large number of marbles are released, they will settle down at the bottom, forming the contour of a Bell Curve. Most marbles will agglomerate at the center (smaller deviation) with few on the edge of the board.
In 1935, three different electricity companies (e.g. Pacific Gas and Electric Company, Commonwealth Edison Company) created an electricity data physicalization model to visualize the power consumption of their customers so that the company can better forecast the upcoming power demand. The model has one short axis and one long axis. The short axis indicates "day", whereas the long axis spans the whole year. The viewers can gain perspective on when customers consume electricity the most during the day and how does the consumption change across different seasons. The model was built manually by cutting wooden sheets and stacked all pieces together.
Researchers began to realize that data physicalization models can not only help agents manage/plan certain tasks, but also can greatly simplify very complex problems by letting users manipulate data in the real world. Therefore, from an epistemic perspective, physical manipulation enables users to uncover hidden patterns that cannot be easily detected. Max Perutz received Nobel Prize in Chemistry in 1962 for his distinguished work in discovering the structure of the globular protein. When a narrow X-ray passes through the haemoglobin molecule, the diffraction pattern can review the inner structure of the atomic arrangements. One of Perutz's works within this research involved creating a physicalized haemoglobin molecule which enables him to manipulate and inspect the structure in a tangible way.
In the book, Bertin designed a matrices visualization device called Domino which let users manipulate row and column data. The combination of row and column can be considered as a two-dimensional data space. In Semiology of Graphics, Bertain defined what variables can be reordered and what variables cannot. For example, time can be considered as a one direction variable. We should keep it in a natural order. Compared with the aforementioned work, this model emphasized the visual thinking aspect of data physicalization and supports a variety of data types such as maps, matrices, and timelines. By adjusting the data entries, an analyst can find patterns inside the datasets and repeatedly use Domino on different datasets.
More recent physicalization examples include using LEGO bricks to keep track of project progress. For example, people used LEGO to record their thesis writing progress. Users can use the LEGO board to set concrete steps before pushing to real publications such as data analysis, data collection, development, etc. Another application involves using LEGO in bug tracking. For software engineers, keeping track of the issue of the code base is a crucial task and LEGO simplify this progress by physicalize the issues.
A specific application of data physicalization involves building tactile maps for visually impaired people. Past example include using microcapsule paper to build tactile maps. With the help of digital fabrication tool such as laser cutter, researchers in Fab Lab at RWTH Aachen University has used it to produce relief-based a tactile map to support visually impaired users. Some tangible user interface researchers combined TUI with tactile maps to render dynamic rendering and enhance collaboration between vision impaired people (e.g. FluxMarkers).
References
physicalization
Visualization (research)
physicalization | Data physicalization | [
"Engineering"
] | 1,453 | [
"Data modeling",
"Data engineering"
] |
76,217,142 | https://en.wikipedia.org/wiki/Tuan%20Andrew%20Nguyen | Tuan Andrew Nguyen (born 1976, Sài Gòn, Vietnam) is a Vietnamese-American artist known for moving-image works, sculptures and installations. His work taps into counter-memory, testimony and dialogue as forms of political resistance and empowerment, highlighting unofficial and underrepresented histories involving the fragmented consciousness of colonial inheritance and the cultural estrangement of expatriation and repatriation. He interweaves factual and speculative elements—archival resources, fiction, explorations of material memory embedded in objects (animism), and supernatural realms—in order to rework dominant narratives into poetic vignettes that imagine alternate forms of healing, survival and political potentiality. In 2023, New York Times critic Roberta Smith wrote, "Nguyen is a documentarian and an assembler of broken things with a preference for collaboration. His work aims to heal the fragmented lives and retrieve the suppressed memories of the marginalized people most affected by colonization, war and displacement, especially in Vietnam."
Nguyen's work belongs to the public art collections of the Museum of Modern Art, Solomon R. Guggenheim Museum, Singapore Art Museum and San Francisco Museum of Modern Art (SFMOMA), among others. In 2023, he received the Joan Miró Prize. He has exhibited at international exhibitions and film festivals including the Whitney Biennial, Sharjah Biennial, Berlin Biennale and Manifesta, and a solo show at the New Museum. He is a cofounding member of the artist collective The Propeller Group and is based in Ho Chi Minh City, Vietnam.
Early life and career
Nguyen was born in 1976 in Sài Gòn, Vietnam. He and his family emigrated as refugees to the United States in 1979, and he grew up in Oklahoma and then Southern California. Initially a pre-med student, he earned a BFA from the University of California, Irvine in 1999. As an undergraduate he developed an inclination toward collective artmaking as a member of a graffiti crew; this would solidify in his later work with The Propeller Group and solo projects with various ethnic communities. He continued his art studies at California Institute of the Arts under Daniel Joseph Martinez, earning an MFA in 2004.
That same year Nguyen returned to Vietnam and settled in Ho Chi Minh City, in part out of a desire to understand and learn from his grandmother, who became a writer and published poet there at a young age. After the move, the country and its trials became a recurrent subject in his work. Nguyen's early exhibitions included solo shows at Voz Alta Projects (San Diego, 2004) and Galerie Quynh (Ho Chi Minh City, 2008), the 2006 Asia Pacific Triennial, and screenings at international and experimental film festivals. He cofounded the artist-run alternative space Sàn Art in Ho Chi Minh City in 2007.
The Propeller Group
In 2006, Nguyen co-founded The Propeller Group (TPG) with artist Phunam Thuc Ha; they were joined by Matt Lucero in 2008. For roughly a decade, TPG was the focus of Nguyen's efforts with large-scale collaborative projects that bridged fine art and mainstream media, including online viral campaigns, film productions, television commercials and installation art. TPG's work often combined contradictory concepts and strategies: public and private, political ideology and branding, low and high culture. The collective was featured in a traveling retrospective organized by the Museum of Contemporary Art Chicago (2016) and selected for the Guangzhou Triennial (2012), Venice Biennale (2015), and surveys at the Guggenheim Museum, New Museum and SFMOMA. In 2017, Phunam and Lucero withdrew from the group; Nguyen is still associated with TPG.
Work and reception
Critics describe Nguyen's individual projects as more personal, subtler and more ambitious than his work with TPG. They draw upon both his own family's experience and the stories of others—Vietnamese-Senegalese people, the Aboriginal Ngurrara of Western Australia, migrants in Marseilles and endangered animals, among others. His projects have remained collaborative, as well as participatory, directly engaging with communities to devise and enact narratives, intergenerational dialogues, personal accounts and performances. The resulting works have been noted for their reflective, multi-perspectival character, lack of didacticism and refusal to reduce or erase cultural contradictions.
Nguyen frequently combines moving images and objects in his installations. His videos and films have dramatized paradoxes involving belief, mythology, decolonial politics, cultural legacies, consumerism and ecology. According to Artforum critic Murtaza Vali, Nguyen's sculptural work "seeks to give visibility and voice to displaced and marginalized communities, often through 'testimonial objects,' i.e., physical repositories of memory that retain the agency to narrate these recollections." For example, he has repurposed objects ranging from decorative animal statuary to salvaged bombshells from the American war in Vietnam (1955–75) in order to examine the traumas of war and extinction (e.g., A Rising Moon Through The Smoke, 2022). His Enemy's Enemy: A Monument to a Monument (2009) consisted of a baseball bat with the image of Buddhist monk Thich Quang Duc's 1963 self-immolating protest against the US-backed South Vietnamese government carved into it; the sculpture commented on cultural inheritance, a newly unveiled official monument to the event, and the use of such objects to serve political exigencies.
Since 2017, Nguyen has had solo exhibitions at institutions including the Asia Society, Joslyn Art Museum, Ulrich Museum, Centre for Contemporary Arts in Glasgow and New Museum ("Radiant Remembrance," 2023), among others; the New Museum exhibition was featured on the PBS NewsHour in August 2023. He has also shown at the James Cohan Gallery in New York and Galerie Quynh.
Individual works and exhibitions
In his expansive exhibition "Empty Forest" (2017, Factory Contemporary Arts Center), Nguyen examined the complex, relationship in Vietnam between humans and animals, one involving traditional mythology, contemporary ecology and capitalist consumption. Placed in dialogue with an otherworldly menagerie of strange hybrid creatures, the two-channel video My Ailing Beliefs Can Cure Your Wretched Desires (2017) examined the paradoxical connection between archaic medicinal and spiritual beliefs, illegal trade in endangered animals and the extinction of species. The video was set in both real and surreal landscapes and revolved around a fictional Socratic dialogue (in voiceover) between the wandering spirits of the last Javan rhinoceros (poached in 2010) and the last giant softshell turtle concerning political revolution against humans. The exhibition's objects—neoritualistic masks, costumes-sculptures and mutations of animal statues on altar-like pedestals bathed in eerie purple neon light—together suggested a chilling spirit forest haunted by violence, greed and devastation; the show's title, "Empty Forest," is an ecological term for viable ecosystems void of large mammals due to hunting, poaching or deforestation.
In the forty-minute video The Island (2017, Whitney Biennial), Nguyen collapsed past and future and questioned notions of identity, trauma, history and exile. The video was set on the tiny Malaysian island of Pulau Bidong—the largest refugee camp after the Vietnam War, now overgrown with jungle, where Nguyen and his family briefly stayed. The video mixed historical footage with a dystopian narrative about the last two humans on earth: a man who is the island's last inhabitant and a woman scientist who washes up on shore after witnessing a nuclear holocaust. The Boat People (2020) took up similar themes, while reclaiming the eponymous derogatory term. It juxtaposed hand-carved wooden objects with a video fable set in an unspecified post-apocalyptic future that portrayed a band of scrawny children in steampunk headdresses navigating the open seas in a whimsical yellow boat. They wade ashore a deserted, sun-dappled island and collect objects that survived over time, trying to piece together the stories and history of a world they never knew.
In two video installations, Nguyen considered communities created and divided by colonial conflict, specifically the First Indochina War (1946–54). The collaborative, four-channel video and photography work The Specter of Ancestors Becoming (2019) was commissioned for the Sharjah Biennial. Its imagined, real and poetic cross-cultural exchanges depicted intergenerational memories, desires and conflicts from the small Vietnamese-Senegalese population in Dakar—descendants of colonial Senegalese troops conscripted to fight for the French in the war (the tirailleurs sénégalais) who took Vietnamese wives and then returned. Because No One Living Will Listen (2023), a two-channel work using CGI, centered on a Vietnamese woman mourning her father, a Moroccan soldier and defector who died when she was a baby; its video screen was bounded on either side by white khaki fabric embroideries—enlarged versions of the propaganda pamphlets that Viet Minh insurgents dropped on French colonial troops urging them to defect.
Nguyen's "Unburied Sounds" (2022, James Cohan) was an exhibition of video and sculptural works (used in the video) crafted from fragments of discarded Vietnam War remnants. Weaving fiction, folkloric ghost stories, history and testimony, the show explored the ways in which material contains memory and holds potential for salvation, healing and reincarnation—often through transformation by art. The video, The Unburied Sounds of a Troubled Horizon, centered on a woman who runs a small junkyard with her mother on the outskirts of Quang Tri one of the most heavily bombed areas in history, still haunted by a legacy of death and dismemberment, physical residue and the ongoing danger of unexploded ordnance (UXO). The woman scavenges and sells the discarded war metals, but also compulsively transforms them into musical instruments with healing properties (e.g., the temple gong sculpture, Unexploded Resonance) and mobiles that seem to channel the aesthetics and perhaps the spirit of sculptor Alexander Calder, who campaigned against the war in the 1960s.
Collections and awards
Nguyen's work belongs to the public art collections of The Burger Collection (Switzerland), Carré d’Art (Musée d’art contemporain de Nîmes, France), Colección Diéresis (México), Kadist, Kemper Art Museum, Museum of Fine Arts, Houston, Museum of Modern Art, Philadelphia Museum of Art, Queensland Art Gallery and Gallery of Modern Art (QAGOMA), Singapore Art Museum, San Francisco Museum of Modern Art, Smithsonian American Art Museum, Solomon R. Guggenheim Museum and Whitney Museum, among others. He received the Joan Miró Prize (2023), a VIA Art Fund acquisition grant (2020), a Civitella Ranieri Foundation fellowship (2019), and an artist residency from Bellas Artes (2019, Bataan, Philippines).
References
External links
Tuan Andrew Nguyen official website
"Artist examines legacy of Vietnam War and its impact on his own life in new exhibition," PBS News Hour feature, 2023
Tuan Andrew Nguyen interview, Art in America, 2023
Tuan Andrew Nguyen interview ARTnews, 2020
Tuan Andrew Nguyen, James Cohan Gallery
Tuan Andrew Nguyen, Gallery Quynh
Video artists
Contemporary sculptors
Multimedia artists
Vietnamese contemporary artists
Vietnamese film directors
Vietnamese artist groups and collectives
Living people
1976 births
Film directors from Ho Chi Minh City | Tuan Andrew Nguyen | [
"Technology"
] | 2,394 | [
"Multimedia",
"Multimedia artists"
] |
76,217,266 | https://en.wikipedia.org/wiki/Kandis%20Leslie%20Abdul-Aziz | Kandis Leslie Abdul-Aziz is an American chemical and environmental engineer known for the development of technologies that turn agricultural waste into a filtration system for water. While previously residing at the University of California, Riverside, she worked as an assistant professor in the Chemical and Environmental Engineering Department. Before joining the University of Southern California, she directed the Sustainable Lab, a diagnostic center for repurposing waste materials into innovative products that offer benefits to society.
Career and research
After obtaining her Bachelor's in Chemistry in 2007 from Temple University, she secured a role testing the refinery's waste-water and examining refined petroleum goods such as phenol and acetone at a refinery located near the Schuylkill River in South Philadelphia. Abdul-Aziz later worked for the Philadelphia Police Department as a chemist specializing in forensic science from 2009-2011. She then branched out to entrepreneurship and founded her own company called Nardo Technology in 2016, named after Leonardo Da Vinci. While she founded her company she simultaneously furthered her education by pursuing a Ph.D. in Chemistry at the University of Illinois, Urbana-Champaign. Once Abdul-Aziz finished her Doctorate, she became an assistant professor at the University of California, Riverside in 2018, working in the Chemical and Environmental Engineering department. In 2020, Abdul-Aziz received a $30,000 Hellman Fellowship to support her development of expandable technology in plastic waste repurposing.
Abdul-Aziz was recognized as one of the top up-and-coming minds in the 2022 issue of the Popular Science magazine "The Brilliant 10." Abdul-Aziz focuses on repurposing waste materials such as corn stover and citrus peels into activated carbon filters for environmental cleanup. She also explores converting plastic trash and developing absorbent materials to capture and reuse carbon dioxide emissions, aiming to create practical recycling solutions for a more sustainable circular economy.
Abdul-Aziz holds the Pasqual and Adelina Early Career Chair in Civil and Environmental Engineering department at the University of Southern California. She leads the Sustainable Catalysis and Materials Laboratory, focusing on transforming waste materials like carbon dioxide, citrus peel and plastic into valuable products through catalysis. Her work, recently recognized with a 2024 Alfred P. Sloan Research Fellowship in Chemistry, aims to create recyclable products and mitigate global warming by developing innovative reuse processes. Kandis Leslie Abdul-Aziz's approach involves integrating sustainability and economic viability, with a focus on practical solutions for industry and policymakers.
Her work further centers around innovational approaches to waste management, as sustainable catalysis has garnered much recognition. Kandis Leslie Abdul-Aziz received a $538,000 National Science Foundation CAREER Award in 2021 for her research on converting greenhouse gas into energy chemicals at the University of California Riverside. Her research has also been pivotal in advancing sustainable chemical processes for low-carbon chemical production. Notably, her development of carbon sequestration technologies for direct methanation in an integrated CO2 capture and utilization process represents a significant step towards enhancing the efficiency and sustainability of CO2 conversion technologies.
References
Wikipedia Student Program
Living people
Temple University
University of Illinois Urbana-Champaign alumni
University of California, Riverside faculty
University of Southern California faculty
21st-century African-American academics
21st-century American academics
21st-century African-American scientists
21st-century African-American women
Environmental engineers
African-American chemists
21st-century American chemists
American women chemists
Year of birth missing (living people) | Kandis Leslie Abdul-Aziz | [
"Chemistry",
"Engineering"
] | 701 | [
"Environmental engineers",
"Environmental engineering"
] |
76,217,482 | https://en.wikipedia.org/wiki/Thallide | Thallides are compounds containing anions composed of thallium. There are several thallium atoms in a cluster, and it does not occur as a single Tl− in thallides. They are a subclass of trielides, which also includes gallides and indides. A more general classification is polar intermetallics, as clusters contain delocalized multicentre bonds. Thallides were discovered by Eduard Zintl in 1932.
Mixed anion compounds with thallides include halides (bromides and chlorides), oxides, and tetrelates (silicate, germanate).
Production
Thallide compounds can be produced by melting metals together in a tantalum crucible under an inert argon atmosphere. However if arsenic is included in the mix, it can react with the crucible wall.
A low temperature production route, is to dissolve an alkali metal in liquid ammonia, and use that to reduce a thallium salt, like thallium iodide.
Properties
Thallide compounds are dense, dense to X-rays and usually metallic grey or black in appearance.
Thallide clusters mostly do not follow Wade-Mingos rules or the Zintl–Klemm concept, as they have too small a negative charge. They can be called "hypoelectronic".
Reactions
In liquid ammonia, oxidation occurs yielding metal amides, and thallium metal.
Thallides react with water and air.
List
References
Thallium compounds
Anions | Thallide | [
"Physics",
"Chemistry"
] | 318 | [
"Ions",
"Matter",
"Anions"
] |
76,217,872 | https://en.wikipedia.org/wiki/Muskegon%20Chemical%20Co. | The Muskegon Chemical Company is a 19.6 acre Superfund site located in Muskegon County, Michigan.
History
The Muskegon Chemical Co. was founded in 1957, and ran until 1993. The site was founded by John R. Yost Jr. who was also the vice president and chief operating officer at the Ott/Story/Cordova Chemical Company. He founded Muskegon Chemical Company in the Whitehall Industrial Park to manufacture chemicals primarily for the pharmaceutical industry.
Impacts and cause
The site was contaminated with dichloroethane, bis-(2-chlorophyll)ether, and triglycol dichloride. It was determined that there was a leak in the drainage system inside the facility that contaminated the soil and groundwater around the site.
Cleanup
The remediation process involves several steps to address groundwater contamination. Groundwater is extracted to prevent the contaminated plume from reaching Mill Pond Creek. Carbon adsorption is employed to remove organic contaminants. The treated water is safely discharged into the Whitehall Area Publicly Owned Treatment Works. Regular monitoring of surface water, groundwater, soil, and air evaluates the system’s effectiveness.
Current day
The Muskegon Chemical Co. currently has "Hazardous Ranking" score of 34.19 And the status of the site is “Completed” which means that All the facilities necessary for cleanup have been built.
References
Superfund sites
Chemical companies of the United States
Companies established in 1957 | Muskegon Chemical Co. | [
"Technology"
] | 297 | [
"Hazardous waste",
"Superfund sites"
] |
61,046,889 | https://en.wikipedia.org/wiki/AaaI | AaaI is a Type II restriction enzyme found in Acetobacter aceti ss aceti. Its prototype is XmaIII. It is in the subtype category 'P', meaning that it has symmetric target and cleavage sites.
Its recognition sequence is 5' CGGCG and 3' GCCGGC and its cut is 5' ---C GGCCG--- 3' and 3' ---GCCGG C--- 5'.
Its isoschizomers are BseX3I, BstZI, EagI, EclXI, Eco52I, SenPT16I, XmaIII, meaning that they have the same recognition sequences, but have been isolated from different bacteria, so they likely have different reaction conditions, making them different.
References
Restriction enzymes
Bacterial enzymes | AaaI | [
"Biology"
] | 172 | [
"Genetics techniques",
"Restriction enzymes"
] |
61,047,346 | https://en.wikipedia.org/wiki/Estrone/progesterone/testosterone | Estrone/progesterone/testosterone (E1/P4/T), sold under the brand name Tristeron or Tristerone, is an injectable combination medication of estrone (E1), an estrogen, progesterone (P4), a progestogen, and testosterone (T), an androgen/anabolic steroid, which was used in the treatment of functional uterine bleeding in women. It contained 6 mg estrone, 50 mg progesterone, and 25 mg testosterone in microcrystalline aqueous suspension and was administered by intramuscular injection. The medication was manufactured by Wyeth and was marketed by 1951. It is no longer available.
See also
List of combined sex-hormonal preparations § Estrogens, progestogens, and androgens
References
Abandoned drugs
Combined estrogen–progestogen–androgen formulations | Estrone/progesterone/testosterone | [
"Chemistry"
] | 195 | [
"Drug safety",
"Abandoned drugs"
] |
61,047,951 | https://en.wikipedia.org/wiki/Honor%2010 | The Honor 10 is a smartphone made by Huawei under their Honor sub-brand.
The phone was released in April 2018, outside China in May 2018, and succeeded by the Honor 20 in June 2019. It uses the Kirin 970 SoC and is equipped with a 5.84" 2280x1080 LCD display.
It was available in a version with 4 GB memory and 64 GB of storage capacity, and a 'Premium edition' offering 6 GB of memory and double the amount of storage. In July, Honor launched the Honor 10 GT, further upgrading the model to 8 GB of memory and offering improved GPU performance and camera software. In June 2021, Huawei announced that the Honor 10 line would be eligible for installing HarmonyOS.
It was noted for being one of the first phones on the market featuring an ultrasonic fingerprint reader, as opposed to the conventional capacitive type.
Reception
The phone was praised for being good value for money, offering a good build and screen quality, decent performance and camera quality, but reviewers criticized the phone for lacking wireless charging and water resistance.
References
Mobile phones introduced in 2018
Android (operating system) devices
Huawei Honor
Mobile phones with multiple rear cameras
Discontinued flagship smartphones | Honor 10 | [
"Technology"
] | 247 | [
"Discontinued flagship smartphones",
"Flagship smartphones"
] |
61,048,240 | https://en.wikipedia.org/wiki/Noa%20Marom | Noa Marom is an Israeli materials scientist and computational physicist at Carnegie Mellon University. She was awarded the International Union of Pure and Applied Physics Young Scientist Prize.
Early life and education
Marom studied materials engineering at Technion – Israel Institute of Technology and earned her bachelor's degree in 2003. After graduating, she worked as an application engineer in the Process and Control Division. She joined the Weizmann Institute of Science for her doctoral studies, earning a PhD under the supervision of Leeor Kronik in 2010. Marom won the Shimon Reich Memorial Prize for her PhD thesis. Her doctoral work considered the predictions of dispersion interactions and electronic structure using computational chemistry. She worked on molecules including copper phthalocyanine, azabenzenes and hexagonal boron nitride.
Research and career
Marom joined the University of Texas at Austin as a postdoctoral researcher in 2010. She moved to Tulane University as an assistant professor in physics in 2013. In 2016 Marom was appointed as an assistant professor at Carnegie Mellon University. She is a member of the Pittsburgh Quantum Institute.
Her work considers molecular crystals that are bound by Van der Waals interactions. As Van de Waal's interactions are weak, molecules can adopt a range of crystal structures. These are known as polymorphs, and can be predicted using computational simulations. The chemical and physical properties of these systems are determined by their crystal structure. Marom develops genetic algorithms that predict the structure of molecular crystals using the principles of survival of the fittest. Marom's work uses density functional theory and many-body perturbation theory to study complex atomic systems. She has investigated the GW approximation for molecules. The materials investigated by Marom can be used for dye-sensitized solar cells.
Awards and honors
In 2018 Marom was awarded the International Union of Pure and Applied Physics Young Scientist Prize.
References
Israeli women academics
Israeli women scientists
Technion – Israel Institute of Technology alumni
Weizmann Institute of Science alumni
Carnegie Mellon University faculty
Computational chemists
Year of birth missing (living people)
Living people
Recipients of the IUPAP Early Career Scientist Prize | Noa Marom | [
"Chemistry"
] | 434 | [
"Computational chemistry",
"Theoretical chemists",
"Computational chemists"
] |
61,049,743 | https://en.wikipedia.org/wiki/Zig%20%28programming%20language%29 | Zig (Also known as Ziglang) is an imperative, general-purpose, statically typed, compiled system programming language designed by Andrew Kelley. It is free and open-source software, released under an MIT License.
A major goal of the language is to improve on the C language, (also taking inspiration from Rust), with the intent of being even smaller and simpler to program in, while offering more functionality. The improvements in language simplicity relate to flow control, function calls, library imports, variable declaration and Unicode support. Further, the language makes no use of macros or preprocessor instructions. Features adopted from modern languages include the addition of compile time generic programming data types, allowing functions to work on a variety of data, along with a small set of new compiler directives to allow access to the information about those types using reflective programming (reflection). Like C, Zig omits garbage collection, and has manual memory management. To help eliminate the potential errors that arise in such systems, it includes option types, a simple syntax for using them, and a unit testing framework built into the language. Zig has many features for low-level programming, notably packed structs (structs without padding between fields), arbitrary-width integers and multiple pointer types.
The main drawback of the system is that, although Zig has a growing community, as of 2024, it remains a new language with areas for improvement in maturity, ecosystem and tooling. Also the learning curve for Zig can be steep, especially for those unfamiliar with low-level programming concepts. The availability of learning resources is limited for complex use cases, though this is gradually improving as interest and adoption increase. Other challenges mentioned by the reviewers are interoperability with other languages (extra effort to manage data marshaling and communication is required), as well as manual memory deallocation (disregarding proper memory management results directly in memory leaks).
The development is funded by the Zig Software Foundation (ZSF), a non-profit corporation with Andrew Kelley as president, which accepts donations and hires multiple full-time employees. Zig has very active contributor community, and is still in its early stages of development. Despite this, a Stack Overflow survey in 2024 found that Zig software developers earn salaries of $103,000 USD per year on average, making it one of the best-paying programming languages. However, only 0.83% reported they were proficient in Zig.
Language
Goals
The primary goal of Zig is to be a better solution to the sorts of tasks that are currently solved with C. A primary concern in that respect is readability; Zig attempts to use existing concepts and syntax wherever possible, avoiding the addition of different syntax for similar concepts. Further, it is designed for "robustness, optimality and maintainability", including a variety of features to improve safety, optimization, and testing. The small and simple syntax is an important part of the maintenance, as it is a goal of the language to allow maintainers to debug the code without having to learn the intricacies of a language they might not be familiar with. Even with these changes, Zig can compile into and against existing C code; C headers can be included in a Zig project and their functions called, and Zig code can be linked into C projects by including the compiler-built headers.
In keeping with the overall design philosophy of making the code simple and easy to read, the Zig system as a whole also encompasses a number of stylistic changes compared to C and other C-like languages. For instance, the Rust language has operator overloading which means a statement like might actually be a function call to a type’s overloaded version of the plus operator. Further, that function might panic which might pre-empt any following code. In Zig, if something calls a function, it looks like a function call; if it doesn’t, it doesn’t look like a function call. If it raises an error, it is explicit in the syntax, error handling is handled through error types and can be handled with catch or try.
The goals of Zig are in contrast to those of many other languages designed in the same time period, like Go, Rust, Carbon, and Nim. Generally, these languages are more complex with added features like operator overloading, functions that masquerade as values (properties), and many other features intended to aid in building large programs. These sorts of features have more in common with C++’s approach, and these languages are more along the lines of that language. Zig has a more conservative extension of the type system, supporting compile time generics and accommodating a form of duck typing with the directive.
Memory handling
One of the primary sources of bugs in C programs is the memory management system, based on malloc. malloc sets aside a block of memory for use in the code and returns a reference to that memory as a pointer. There is no system to ensure that memory is released when the program no longer needs it, which can lead to programs using up all available memory, a memory leak. More common is a dangling pointer that does not refer to a properly allocated memory object.
A common solution to these problems is a garbage collector (GC), which examines the program for pointers to previously allocated memory, and removing any blocks that no longer have anything pointing to them. Although this greatly reduces, or even eliminates, memory errors, GC systems are relatively slow compared to manual memory management, and have unpredictable performance that makes them unsuited to systems programming. Another solution is automatic reference counting (ARC), which implements the same basic concept of identifying blocks of disused memory, but does so at pointer creation and destruction time by maintaining the number of pointers to a block, meaning there is no need to perform exhaustive pointer searches, which are rendered unnecessary at the cost of adding reference counter adjustment overhead to every pointer creation and destruction operation.
Zig aims to provide performance similar to or better than C, so GC and ARC are not suitable solutions. Instead, it uses a modern, , concept known as option types. Instead of a pointer being allowed to point to nothing, or nil, a separate type is used to indicate data that is optionally empty. This is similar to using a structure with a pointer and a boolean that indicates whether the pointer is valid, but the state of the boolean is invisibly managed by the language and does not need to be explicitly managed by the programmer. So, for instance, when the pointer is declared it is set to "unallocated", and when that pointer receives a value from a malloc, it is set to "allocated" if the malloc succeeded.
The advantage to this model is that it has very low or zero overhead; the compiler has to create the code to pass along the optional type when pointers are manipulated, as opposed to a simple pointer, but this allows it to directly express possible memory problems at compile time with no runtime support. For instance, creating a pointer with a null value and then attempting to use it is perfectly acceptable in C, leading to null-pointer errors. In contrast, a language using optional types can check that all code paths only attempt to use pointers when they are valid. While this does not eliminate all potential problems, when issues do occur at runtime the error can be more precisely located and explained.
Another change for memory management in Zig is that the actual allocation is handled through s describing the action, as opposed to calling the memory management functions in libc. For instance, in C if one wants to write a function that makes a string containing multiple copies of another string, the function might look like this:
const char* repeat(const char* original, size_t times);
In the code, the function would examine the size of and then malloc that length to set aside memory for the string it will build. That malloc is invisible to the functions calling it, if they fail to later release the memory, a leak will occur. In Zig, this might be handled using a function like:
fn repeat(allocator: *std.mem.Allocator, original: []const u8, times: usize) std.mem.Allocator.Error![]const u8;
In this code, the variable is passed a struct that describes what code should perform the allocation, and the function returns either the resulting string or, using the optional type as indicated by the , an Allocator.Error. By directly expressing the allocator as an input, memory allocation is never "hidden" within another function, it is always exposed to the API by the function that is ultimately calling for the memory to be allocated. No allocations are performed inside Zig’s standard library. Further, as the struct can point to anything, one can use alternative allocators, even ones written in the program. This can allow, for instance, small-object allocators that do not use the operating system functions that normally allocate an entire memory page.
Optional types are an example of a language feature that offers general functionality while still being simple and generic. They do not have to be used to solve null pointer problems, they are also useful for any type of value where "no value" is an appropriate answer. Consider a function that returns an integer, and an integer variable, that holds the result. In many languages, a magic number would be placed in to indicate that has not yet been called, while many implementations would just set it to zero. In Zig, this could be implemented as an which sets the variable to a clear "not been called" value.
Another more general feature of Zig that also helps manage memory problems is the concept of , which marks some code to be performed at the end of a function no matter what happens, including possible runtime errors. If a particular function allocates some memory and then disposes of it when the operation is complete, one can add a line to defer a to ensure it is released no matter what happens.
Zig memory management avoids hidden allocations. Allocation is not managed in the language directly. Instead, heap access is done via the standard library, explicitly.
Direct interaction with C
Zig promotes a gradual approach to portability that combines new Zig code with existing C code. To do this, it aims to make interaction with existing C libraries as seamless as possible. Zig imports its own libraries with the directive, typically in this fashion:
const std = @import("std");
Zig code within that file can now call functions inside std, for instance:
std.debug.print("Hello, world!\n", .{});
To work with C code, one simply replaces the with :
const c = @cImport(@cInclude("soundio/soundio.h"));
The Zig code can now call functions in the soundio library as if they were native Zig code. As Zig uses new data types that are explicitly defined, unlike C’s more generic and , a small number of directives are used to move data between the C and Zig types, including and .
Comptime
By using the keyword, the programmer can explicitly have Zig evaluate sections of code at compile time, as opposed to runtime. Being able to run code at compile time allows Zig to have the functionality of macros and conditional compilation without the need for a separate preprocessor language.
During compile time, types become first-class citizens. This enables compile-time duck typing, and is how Zig implements generic types.
For instance, in Zig, a generic linked list type might be implemented using a function like:
fn LinkedList(comptime T: type) type;
This function takes in some type , and returns a custom defining a linked list with that data type.
Compiler
Zig is not just a new language: it also includes a C and C++ compilers, and can be used with either or both languages by leveraging with the commands zig cc and zig c++, providing many headers including the C standard library (libc) and C++ Standard Library (libcxx) for many different platforms. This allows Zig’s cc and c++ sub-commands to act as cross compilers out of the box (similarly to Clang).
Zig treats cross-compiling as a first-class use-case of the language. This means any Zig compiler can compile runnable binaries for any of its target platforms, of which there are dozens. These include not only widely-used modern systems like ARM and x86-64, but also PowerPC, SPARC, MIPS, RISC-V and even the IBM z/Architectures (S390). The toolchain can compile to any of these targets without installing additional software, all the needed support is in the basic system. The experimental support is also provided for less known platforms like AMD and Nvidia GPUs or PlayStation 4 and 5 (with various degree of support).
Cross-compilation is also available for variety of the operating systems (mostly desktop ones). Popular UNIX-like ones and Windows are officially supported (and documented), but (minimal) applications can and have been made for Android (with Android NDK) or iOS.
Zig uses LLVM (written in C++) as a backend for optimization. Since version 0.10 the Zig compiler is written in the Zig programming language, i.e., it is a self-hosting compiler. The self-hosted linker is tightly coupled with the self-hosted compiler.
Packages
Version 0.11.0 bundles an experimental package manager, but no official package repository is available. Instead a package is simply a URL that points to a compressed file. Each package includes a standard `build.zig` file (that the Zig compiler uses by convention to compile the source code) and, ideally, a `build.zig.zon` file containing metadata with name and version of the package.
Examples
Hello World
const std = @import("std");
pub fn main() !void {
const stdout = std.io.getStdOut().writer();
try stdout.print("Hello, {s}!\n", .{"world"});
}
Generic linked list
const std = @import("std");
const stdout = std.io.getStdOut().writer();
fn LinkedList(comptime T: type) type {
return struct {
const Self = @This();
pub const Node = struct {
next: ?*Node = null,
data: T,
};
first: ?*Node = null,
pub fn prepend(
list: *Self,
new_node: *Node,
) void {
new_node.next = list.first;
list.first = new_node;
}
pub fn format(
list: Self,
comptime fmt: []const u8,
options: std.fmt.FormatOptions,
out_stream: anytype,
) !void {
try out_stream.writeAll("( ");
var it = list.first;
while (it) |node| : (it = node.next) {
try std.fmt.formatType(
node.data,
fmt,
options,
out_stream,
1,
);
try out_stream.writeAll(" ");
}
try out_stream.writeAll(")");
}
};
}
pub fn main() !void {
const ListU32 = LinkedList(u32);
var list = ListU32{};
var node1 = ListU32.Node{ .data = 1 };
var node2 = ListU32.Node{ .data = 2 };
var node3 = ListU32.Node{ .data = 3 };
list.prepend(&node1);
list.prepend(&node2);
list.prepend(&node3);
try stdout.print("{}\n", .{list});
try stdout.print("{b}\n", .{list});
}
Output
( 3 2 1 )
( 11 10 1 )
String repetition with allocator
const std = @import("std");
fn repeat(
allocator: *std.mem.Allocator,
original: []const u8,
times: usize,
) std.mem.Allocator.Error![]const u8 {
var buffer = try allocator.alloc(
u8,
original.len * times,
);
for (0..times) |i| {
std.mem.copyForwards(
u8,
buffer[(original.len * i)..],
original,
);
}
return buffer;
}
pub fn main() !void {
const stdout = std.io.getStdOut().writer();
var arena = std.heap.ArenaAllocator.init(
std.heap.page_allocator,
);
defer arena.deinit();
var allocator = arena.allocator();
const original = "Hello ";
const repeated = try repeat(
&allocator,
original,
3,
);
try stdout.print("{s}\n", .{repeated});
}
Output
Hello Hello Hello
History
The name “Zig” was reportedly chosen through a process involving a Python script that randomly combined letters, starting with the letter “Z” and followed by a vowel or “Y”, in order to generate four-letter words. Despite the intended length, “Zig”, a three-letter word, was ultimately selected from the various combinations produced by the script.
The previous bootstrapping compiler, written in Zig and C++ using LLVM as a back-end, supporting many of its native targets, was removed in version 0.11.
Projects
Bun is a JavaScript and TypeScript runtime written in Zig, using Safari’s JavaScriptCore virtual machine.
Ghostty is a terminal emulator written in Zig.
The TigerBeetle financial transaction database is written in Zig.
See a more comprehensive list of companies and projects utilizing Zig in production.
See also
C
C++
D
Nim
Go
Rust
Carbon
V
References
Citations
Bibliography
External links
Movie: Introducing Zig
Movie: The Road to 1.0
Zig Weekly
High-level programming languages
C (programming language) compilers
Cross-platform software
Cross-platform free software
Embedded systems
Free and open source compilers
Free computer libraries
Programming languages
Programming languages created in 2015
Software using the MIT license
Statically typed programming languages
Systems programming languages | Zig (programming language) | [
"Technology",
"Engineering"
] | 4,022 | [
"Embedded systems",
"Computer science",
"Computer engineering",
"Computer systems"
] |
61,051,395 | https://en.wikipedia.org/wiki/Comparison%20of%20ASCII%20encodings%20of%20the%20International%20Phonetic%20Alphabet | The International Phonetic Alphabet (IPA) consists of more than 100 letters and diacritics. Before Unicode became widely available, several ASCII-based encoding systems of the IPA were proposed. The alphabet went through a large revision at the Kiel Convention of 1989, and the vowel symbols again in 1993. Systems devised before these revisions inevitably lack support for the additions they introduced.
Only language-neutral systems are discussed below because language-dependent ones (such as ARPABET) do not allow for a systematic comparison.
General information
Symbols
Only the symbols in the latest IPA chart are included. The numbers in the leftmost column, according to which the symbols are sorted, are the IPA Numbers. Some of the IPA symbols to which a system lacks a corresponding symbol may still be represented in that system by use of a modifier (diacritic), but such combinations are not included unless the documentation explicitly assigns one for the value.
Coverage
See also
ARPABET
SAMPA
Notes
References
External links
Representation of IPA with ASCII
International Phonetic Alphabet
ASCII
ASCII encodings of the International Phonetic Alphabet | Comparison of ASCII encodings of the International Phonetic Alphabet | [
"Technology"
] | 223 | [
"Computing comparisons"
] |
61,051,630 | https://en.wikipedia.org/wiki/Natural%20methane%20on%20Mars | The reported presence of methane in the atmosphere of Mars is of interest to many geologists and astrobiologists, as methane may indicate the presence of microbial life on Mars, or a geochemical process such as volcanism or hydrothermal activity.
Since 2004, trace amounts of methane (range from 60 ppbv to under detection limit (< 0.05 ppbv)) have been reported in various missions and observational studies. The source of methane on Mars and the explanation for the enormous discrepancy in the observed methane concentrations are still unknown and are under study. Whenever methane is detected, it is rapidly removed from the atmosphere by an efficient, yet unknown process.
History of detections
Methane (CH4) is chemically unstable in the current oxidizing atmosphere of Mars. It would quickly break down due to ultraviolet (UV) radiation from the Sun and chemical reactions with other gases. Therefore, a persistent or episodic presence of methane in the atmosphere may imply the existence of a source to continually replenish the gas.
The first evidence of methane in the atmosphere was measured by ESA's Mars Express orbiter with an instrument called the Planetary Fourier Spectrometer. In March 2004, the Mars Express science team suggested the presence of methane in the atmosphere at a concentration of about 10 ppbv. This was confirmed soon after by three ground-based telescope teams, although large differences in the abundances were measured between observations taken in 2003 and 2006. This spatial and temporal variability of the gas suggests that the methane was locally concentrated and probably seasonal. It is estimated that Mars produces 270 tons of methane per year.
In 2011, NASA scientists reported a comprehensive search using high-resolution infrared spectroscopy from high-altitude Earth ground-based observatories (VLT, Keck-2, NASA-IRTF) for trace species (including methane) on Mars, deriving sensitive upper limits for methane (< 7 ppbv), ethane (< 0.2 ppbv), methanol (< 19 ppbv) and others (H2CO, C2H2, C2H4, N2O, NH3, HCN, CH3Cl, HCl, HO2 – all with limits at ppbv levels).
In August 2012, the Curiosity rover landed on Mars. The rover's instruments are capable of making precise abundance measurements, but cannot be used to distinguish between different isotopologues of methane and so it cannot determine if it is geophysical or biological in origin. However, the Trace Gas Orbiter (TGO) can measure these ratios and point to their origin.
The first measurements with Curiosity Tunable Laser Spectrometer (TLS) in 2012 indicated that there was no methane —or less than 5 ppb— at the landing site, later calculated to a baseline of 0.3 to 0.7 ppbv. In 2013, NASA scientists again reported no detection of methane beyond a baseline. But in 2014, NASA reported that the Curiosity rover detected a tenfold increase ('spike') in methane in the atmosphere around it in late 2013 and early 2014. Four measurements taken over two months in this period averaged 7.2 ppbv, implying that Mars is episodically producing or releasing methane from an unknown source. Before and after, readings averaged around one-tenth that level. On 7 June 2018, NASA announced the confirmation of a cyclical seasonal variation in the background level of atmospheric methane. The largest concentration of methane detected in situ by the Curiosity rover showed a spike to 21 ppbv, during an event in late June 2019. The Mars Express orbiter happened to be performing spot tracking in that area 20 hours before Curiosity methane detection, as well as 24 and 48 hours after the detection, and the TGO was performing atmospheric observations at around the same time but at a higher latitude.
The Indian Mars Orbiter Mission, which entered orbit around Mars on 24 September 2014, is equipped with a Fabry–Pérot interferometer to measure atmospheric methane, but after entering Mars orbit it was determined that it was not capable of detecting methane, so the instrument was repurposed as an albedo mapper. As of April 2019, the TGO showed that the concentration of methane is under the detectable level (< 0.05 ppbv).
The Perseverance rover (landed Feb 2021) and the Rosalind Franklin rover (due NET 2028) will not be equipped to analyze the atmospheric methane nor its isotopes, so the proposed Mars sample-return mission in the mid-2030s seems the earliest a sample could be analyzed to differentiate a geological from a biological origin.
Potential sources
Geophysical
The principal candidates for the origin of Mars' methane include non-biological processes such as water-rock reactions, radiolysis of water, and pyrite formation, all of which produce H2 that could then generate methane and other hydrocarbons via Fischer–Tropsch synthesis with CO and CO2. It has also been shown that methane could be produced by a process involving water, carbon dioxide, and the mineral olivine, which is known to be common on Mars. The required conditions for this reaction (i.e. high temperature and pressure) do not exist on the surface but may exist within the crust. Detection of the mineral by-product serpentinite would suggest that this process is occurring. An analog on Earth suggests that low-temperature production and exhalation of methane from serpentinized rocks may be possible on Mars. Another possible geophysical source could be ancient methane trapped in clathrate hydrates that may be released occasionally. Under the assumption of a cold early Mars environment, a cryosphere could trap such methane as clathrates in a stable form at depth, which might exhibit sporadic release.
On modern Earth, volcanism is a minor source of methane emission, and it is usually accompanied by sulfur dioxide gases. However, several studies of trace gases in the Martian atmosphere have found no evidence for sulfur dioxide in the Martian atmosphere, which makes volcanism on Mars unlikely to be the source of methane. Although geologic sources of methane such as serpentinization are possible, the lack of current volcanism, hydrothermal activity or hotspots is not favorable for geologic methane.
It had also been proposed that the methane might be replenished by meteorites entering the atmosphere of Mars, but researchers from the Imperial College London found that the volumes of methane released this way are too low to sustain the measured levels of the gas. It has been suggested that the methane was produced by chemical reactions in meteorites, driven by the intense heat during entry through the atmosphere. Although research published in December 2009 ruled out this possibility, research published in 2012 suggested that a source may be organic compounds on meteorites that are converted to methane by ultraviolet radiation.
Lab tests have demonstrated that bursts of methane can be produced when an electrical discharge interacts with water ice and CO2. The discharges from the electrification of dust particles from sand storms and dust devils in contact with permafrost ice may produce about 1.41×1016 molecules of methane per joule of applied energy.
Current photochemical models cannot explain the apparent rapid variability of the methane levels on Mars. Research suggests that the implied methane destruction lifetime is as long as ≈ 4 Earth years and as short as ≈ 0.6 Earth years. This unexplained fast destruction rate also suggests a very active replenishing source. A team from the Italian National Institute for Astrophysics suspects that the methane detected by the Curiosity rover may have been released from a nearby area called Medusae Fossae Formation located about 500 km east of Gale crater. The region is fractured and is likely volcanic in origin.
Biogenic
Living microorganisms, such as methanogens, are another possible source, but no evidence for the presence of such organisms has been found on Mars. In Earth's oceans, biological methane production tends to be accompanied by ethane () generation. The long-term ground-based spectroscopic observation did not find these organic molecules in the Martian atmosphere. Given the expected long lifetimes for some of these molecules, emission of biogenic organics seems to be extremely rare or currently non-existent.
The reduction of carbon dioxide into methane by reaction with hydrogen can be expressed as follows:
CO2 + 4 H2 -> CH4 + 2 H2O (∆G˚' = -134 kJ/mol CH4)
This reaction of CO2 with the hydrogen to produce methane is coupled with the generation of an electrochemical gradient across the cell membrane, which is used to generate ATP through chemiosmosis. In contrast, plants and algae obtain their energy from sunlight or nutrients.
Measuring the ratio of hydrogen and methane levels on Mars may help determine the likelihood of life on Mars. A low H2/CH4 ratio in the atmosphere (less than approximately 40) may indicate that a large part of atmospheric methane could be attributed to biological activities, but the observed ratios in the lower Martian atmosphere were "approximately 10 times" higher "suggesting that biological processes may not be responsible for the observed CH4".
Since the 2003 discovery of methane in the atmosphere, some scientists have been designing models and in vitro experiments testing the growth of methanogenic bacteria on simulated Martian soil, where all four methanogen strains tested produced substantial levels of methane, even in the presence of 1.0 wt% perchlorate salt. Methanogens do not require oxygen or organic nutrients, are non-photosynthetic, use hydrogen as their energy source, and carbon dioxide (CO2) as their carbon source, so they could exist in subsurface environments on Mars. If microscopic Martian life is producing the methane, it probably resides far below the surface, where it is still warm enough for liquid water to exist.
Research at the University of Arkansas published in 2015 suggested that some methanogens could survive on Mars' low pressure in an environment similar to a subsurface liquid aquifer on Mars. The four species tested were Methanothermobacter wolfeii, Methanosarcina barkeri, Methanobacterium formicicum, and Methanococcus maripaludis.
A team led by Gilbert Levin suggested that both phenomena—methane production and degradation—could be accounted for by an ecology of methane-producing and methane-consuming microorganisms.
Even if rover missions determine that microscopic Martian life is the seasonal source of the methane, the life forms probably reside far below the surface, outside of the rover's reach.
Potential sinks
It was initially thought that methane is chemically unstable in an oxidizing atmosphere with UV radiation and so its lifetime in the Martian atmosphere should be about 400 years, but in 2014, it was concluded that the strong methane sinks are not subject to atmospheric oxidation, suggesting an efficient physical-chemical process at the surface that "consumes" methane, generically called a "sink".
A hypothesis postulates that the methane is not consumed at all, but rather condenses and evaporates seasonally from clathrates. Another hypothesis is that methane reacts with tumbling surface sand quartz (silicon dioxide ) and olivine to form covalent Si – bonds. The researchers showed that these solids can be oxidized and gases are ionized during the erosion processes. Thus, the ionized methane reacts with the mineral surfaces and bonds to them.
Images
See also
Atmosphere of Mars
Climate of Mars
Life on Mars
Weather of Mars
Green methanol
References
Atmosphere of Mars
Mars
Astrobiology | Natural methane on Mars | [
"Astronomy",
"Biology"
] | 2,362 | [
"Origin of life",
"Speculative evolution",
"Astrobiology",
"Biological hypotheses",
"Astronomical sub-disciplines"
] |
61,052,505 | https://en.wikipedia.org/wiki/NGC%203048 | NGC 3048 is a pair of spiral galaxies located in the constellation Leo. It was discovered on April 27, 1864, by German astronomer Albert Marth. The object consists of a visual pair of galaxies, PGC 1509261 and PGC 28595. PGC 1509261 is likely a physical pair with a much fainter galactic object not a part of the New General Catalogue, J095458+162726.
See also
List of NGC objects (3001–4000)
References
Spiral galaxies
Leo (constellation)
3048
Astronomical objects discovered in 1864
028595 | NGC 3048 | [
"Astronomy"
] | 123 | [
"Leo (constellation)",
"Constellations"
] |
61,053,401 | https://en.wikipedia.org/wiki/Danuta%20Gierulanka | Danuta Gierulanka (1909–1995) was a Polish mathematics educator, psychologist, philosopher, and translator. She was associated with Roman Ingarden and known for her work in phenomenology and the philosophy of mathematics.
Mathematics educator
Gierulanka was born in Kraków on 30 June 1909; her father was a civil servant. She studied mathematics at the Jagiellonian University from 1927 to 1932, completing a master's degree with a thesis on Periodic solutions of differential equations, and stayed there for another year for a teaching credential. From 1933 to 1938 she worked as a high school teacher of mathematics, science, and philosophy at two Kraków gymnasia.
Psychologist
Gierulanka returned to the Jagiellonian University in 1938, as a psychology student working in the Laboratory of Experimental Psychology with Władysław Heinrich. Her studies were interrupted by World War II, during which she and her brother, physicist Jerzy Gierula, taught in secret. She completed her doctorate in 1947. Her dissertation, O przyswajaniu sobie pojęć geometrycznych [On Grasping Geometrical Notions], was published as a book in 1958.
Gierulanka remained at the Jagiellonian University, and in 1953 became an adjunct in mathematical analysis at the university, with the plan of writing a habilitation thesis combining mathematical analysis with psychology. However, this did not materialize and in 1957 she returned to the Laboratory of Experimental Psychology.
Philosopher
In 1958 Gierulanka moved again, becoming an adjunct in philosophy.
She became interested in Roman Ingarden's work in phenomenology, and wrote a habilitation thesis in 1962 on the phenomenology of mathematics, Zagadnienie swoistoici poznania matematycznego [On the Peculiarity of Mathematical Cognition], also published at the same time as a book.
Failing to obtain a permanent position in philosophy, she returned to a posting in psychology at Jagiellonian, from which she retired in 1971. She died on 29 April 1995 in Kraków.
After her habilitation work, Gierulanka became one of the editors of Ingarden's collected works. She also translated works of Ingarden, Edmund Husserl, and Edith Stein into Polish.
References
Further reading
1909 births
1995 deaths
Polish women mathematicians
20th-century Polish mathematicians
Polish women psychologists
Polish psychologists
Polish women sociologists
Polish women philosophers
Mathematics educators
Philosophers of mathematics
Jagiellonian University alumni
Academic staff of Jagiellonian University
Translators to Polish
20th-century psychologists
20th-century Polish philosophers
20th-century Polish translators
Polish educators
20th-century Polish women educators
20th-century Polish educators
Polish women academics | Danuta Gierulanka | [
"Mathematics"
] | 554 | [
"Philosophers of mathematics"
] |
61,054,835 | https://en.wikipedia.org/wiki/QFAB%20Bioinformatics | QFAB Bioinformatics is a Queensland-based organisation concerned with the provision of resources in bioinformatics, biostatistics and specialised computing platforms. QFAB operates Australia-wide and is a key contributor to the EMBL Australia Bioinformatics Resource.
History
QFAB was established in 2007,
with funding from the Queensland Government's National and International Research Alliances Program, as a joint venture between The University of Queensland, Queensland University of Technology, Griffith University, CSIRO’s Australian eHealth Research Centre and the Queensland Government’s Department of Agriculture, Fisheries and Forestry.
Mark Ragan from the Institute of Molecular Bioscience (IMB) and Anthony Maeder from the Australian eHealth Research Centre led QFAB's establishment and appointed Jeremy Barker as CEO (2007–2014) to address three critical issues then facing bioinformatics in Queensland:
integrated data and high-performance computing in a secure environment
affordable network bandwidth
access to expert personnel
In 2015, Dominique Gorse became CEO of QFAB and led the strategic alliance with QCIF, the Queensland Cyber Infrastructure Foundation; the two organisations merged in April 2016. QCIF operates significant high-performance computing, cloud computing and data storage resources, is part of the national eResearch infrastructure.
Queensland Cyber Infrastructure Foundation
QFAB Bioinformatics is a unit of the Queensland Cyber Infrastructure Foundation (QCIF), a not-for-profit member-based organisation.
Members
Central Queensland University
Griffith University
James Cook University
Queensland University of Technology
The University of Queensland
University of Southern Queensland
Affiliate member
University of the Sunshine Coast
Galaxy Australia
QFAB and QCIF, together with the University of Melbourne's Melbourne Bioinformatics, and the University of Queensland's Research Computing Centre jointly built and operate Galaxy Australia, which is a major feature of the Genomics Virtual Laboratory,
based on the Galaxy (computational biology) scientific workflow system.
References
Bioinformatics organizations
2007 establishments in Australia | QFAB Bioinformatics | [
"Biology"
] | 403 | [
"Bioinformatics",
"Bioinformatics organizations"
] |
61,055,772 | https://en.wikipedia.org/wiki/Celestri | The Celestri Multimedia LEO System was a planned Low Earth orbit (LEO) satellite constellation, which was intended to offer global, low-latency broadband Internet services via Ka-band radio links. It was planned by Motorola circa 1997-1998 as one of the earliest "Internet in the sky" constellations, and as a successor to the company's Iridium satellite constellation, but never built or launched.
The Celestri constellation was envisioned to consist of 63 operational satellites in 7 orbital planes, inclined at 48° with respect to the Equator, plus up to 7 in-orbit spares. Satellites in each plane would follow circular orbits at an altitude of 1400 kilometers. Each satellite was envisioned to contain all hardware and software needed to route traffic throughout the network, including Earth-to-space in the 28.6-29.1 GHz and 29.5-30.0 GHz bands, space-to Earth in the 18.8-19.3 GHz and 19.7-20.2 GHz bands, and space-to-space connections via optical inter-satellite links. Satellites were expected to employ phased array antennas supporting 432 uplink beams and 260 downlink beams per satellite, provided by Raytheon, to communicate with Celestri ground stations, which would have equivalent antenna aperture sizes from 0.3 to 1 meter to support communications at rates from 2.048 to 155.52 Mbps.
Celestri's anticipated cost was $12.9 billion. In May 1998, Motorola announced that it was dropping its plans for the Celestri system, and instead would invest $750 million in the rival Teledesic constellation. The combined project was ultimately abandoned in 2003.
References
Communications satellite constellations | Celestri | [
"Astronomy"
] | 352 | [
"Astronomy stubs",
"Spacecraft stubs"
] |
61,057,634 | https://en.wikipedia.org/wiki/C21H23N3O2 | {{DISPLAYTITLE:C21H23N3O2}}
The molecular formula C21H23N3O2 (molar mass: 349.426 g/mol, exact mass: 349.1790 u) may refer to:
MDA-19
Panobinostat
Molecular formulas | C21H23N3O2 | [
"Physics",
"Chemistry"
] | 68 | [
"Molecules",
"Set index articles on molecular formulas",
"Isomerism",
"Molecular formulas",
"Matter"
] |
61,057,684 | https://en.wikipedia.org/wiki/C19H27N3O | {{DISPLAYTITLE:C19H27N3O}}
The molecular formula C19H27N3O (molar mass: 313.437 g/mol, exact mass: 313.2154 u) may refer to:
MEPIRAPIM
NDTDI
Ricasetron (BRL-46470)
Molecular formulas | C19H27N3O | [
"Physics",
"Chemistry"
] | 75 | [
"Molecules",
"Set index articles on molecular formulas",
"Isomerism",
"Molecular formulas",
"Matter"
] |
61,058,207 | https://en.wikipedia.org/wiki/Wireless%20Network%20after%20Next | The Wireless Network after Next (WNaN) was a DARPA project to create and demonstrate an advanced tactical mobile ad-hoc network (MANET) that rapidly adapts to soldiers maneuvering in complicated environments, automatically determining the best radio frequencies and network paths to maximize connectivity and throughput. In 2010 it was successfully demonstrated in live military experiments containing up to 100 nodes, the largest military MANET demonstrated to that date.
The Wireless Network after Next consisted of a novel radio platform, created by Cobham plc, and novel networking protocols, created by BBN Technologies:
The WNaN radio was envisioned as a low-cost, hand-held, multi-channel, spectrum-agile, MIMO-capable wireless node, built with inexpensive RF circuit technology. It operated in the 900 MHz to 6 GHz frequency band, and contained multiple radio transceivers for simultaneous transmission and reception across multiple frequency bands at rates greater than 1 megabit/second.
The WNaN network provided highly adaptive communications in a self-organizing, self-healing network. Each radio node acted as a router to automatically perform dynamic spectrum management for spectrum agility, Disruption Tolerant Networking for resilience, and content-based networking for efficient data dissemination. The routers also took full advantage of sending and receiving communications packets in parallel across multiple radio transceivers.
References
"Wireless Network after Next (WNaN) Adaptive Network Development (WAND) API Technical Interchange Meeting (TIM)", DARPA solicitation, April 19, 2007.
DARPA WNaN brochure, September 14, 2010.
"Wireless Network After Next leader drives promising technology forward", Claire Heininger and Michael Ackley, US Army PEO C3T, November 15, 2010.
"WNAN: DARPA’s Idea for Next-Generation Soldier Networks", Defense Industry Daily, Jun 29, 2011.
"The DARPA WNaN network architecture", Jason Redi and Ram Ramanathan, MILCOM 2011, pages 2258-2263.
Wireless networking | Wireless Network after Next | [
"Technology",
"Engineering"
] | 412 | [
"Wireless networking",
"Computer networks engineering"
] |
68,892,101 | https://en.wikipedia.org/wiki/Berkelium%28IV%29%20oxide | Berkelium(IV) oxide, also known as berkelium dioxide, is a chemical compound with the formula BkO2. This compound slowly decays to californium(IV) oxide. It can be converted to berkelium(III) oxide by hydrogen reduction at 600 °C.
2BkO2 + H2 → Bk2O3 + H2O
Production
Berkelium(IV) oxide is produced by burning berkelium metal in air at 1200 °C. It can also be produced by reacting berkelium(III) oxide with oxygen at 600 °C.
References
Berkelium compounds
Oxides
Fluorite crystal structure | Berkelium(IV) oxide | [
"Chemistry"
] | 133 | [
"Oxides",
"Salts"
] |
68,892,195 | https://en.wikipedia.org/wiki/Photo%20response%20non-uniformity | Photo response non-uniformity, pixel response non-uniformity, or PRNU, is a form of fixed-pattern noise related to digital image sensors, as used in cameras and optical instruments. Both CCD and CMOS sensors are two-dimensional arrays of photosensitive cells, each broadly corresponding to an image pixel. Due to the non-uniformity of image sensors, each cell responds with a different voltage level when illuminated with a uniform light source, and this leads to luminance inaccuracy at the pixel level.
High-end and metrology camera vendors tend to characterise this non-uniformity during instrument manufacture. The sensor is illuminated with a standardized light source and a two-dimensional table of correction factors is generated. This table is either carried in camera non-volatile memory and dynamically applied to the image on each capture, or ships with the camera to be applied by an external image processing and correcting pipeline.
See also
Color balance
Color correction
Flat-field correction
Image sensor
Digital photography
Image sensors
Optics | Photo response non-uniformity | [
"Physics",
"Chemistry"
] | 210 | [
"Applied and interdisciplinary physics",
"Optics",
" molecular",
"Atomic",
" and optical physics"
] |
68,892,222 | https://en.wikipedia.org/wiki/Bacteriophage%20AP205 | Bacteriophage AP205 is a plaque-forming bacteriophage that infects Acinetobacter bacteria. Bacteriophage AP205 is a protein-coated virus with a positive single-stranded RNA genome. It is a member of the family Fiersviridae, consisting of particles that infect Gram-negative bacteria such as E. coli.
AP205 was isolated from the gram negative species Acinetobacter. Sewage from Quebec, Canada was scanned for bacteriophages that replicated in Acinetobacter bacteria. AP205 was isolated by enrichment methods from urine by P. J. M. Bouvet. The virus was attached to a pili of Acinetobacter. Using electron microscopy, researchers were able to describe the physical characteristics of AP205.
Structure
The main structural component of Bacteriophage AP205 in the Fiersviridae family is a protein shell. Viruses in this family are not enveloped and are characterized by their icosahedral and spherical shape. The icosahedron shape of the capsid results from the arrangement of 178 copies of the coat protein which provide the virus with its structure. While the virus is icosahedral, the surface protrusions are smoother and less prominent of other viruses, giving the capsid a spherical appearance. The coat proteins form dimeric interactions due to hydrophobic and polar interactions to provide the capsid with a high level of structural rigidity. Before forming these dimers, the coat protein exists in three monomeric conformations, labeled A, B, and C. The A and C subunits of the capsid are folded in an arrangement such that they form a three-fold axis while the B subunit is arranged to form a five-fold axis . The protein shell also includes a single copy of a maturation protein (A protein) that functions in maturation of the virus and pilus attachment in prokaryotes. The virus-like particle (VLP) formation without the maturation protein consists of 60 dimers, 30 of which are made of the subunits A and B. The remaining dimers are "CC dimers", forming a homodimer. The maturation protein replaces a CC dimer, resulting in 178 copies of the coat protein as opposed to the expected 180. Identifying characteristics of the Leviviridae coat proteins include a β-hairpin at the N-terminus, a β-sheet with five strands, and two α-helices at the C-terminus. Bacteriophage AP205 has many secondary protein structures, which contributes to its structural rigidity. The capsid self-assembles in vitro. AP205 is 29 nanometers in diameter, making it one of the largest Fiersviridae viruses known as this time.
Genome
Bacteriophage AP205 contains a (+) sense single stranded RNA genome. The genome length for single stranded RNA phages are short, including that of Bacteriophage AP205. However, the genome of AP205 is longer than other Fiersviridae, containing approximately 4268 nucleotides with coding regions for a lytic protein, maturation protein, coat protein, and an RNA-dependent RNA polymerase. The AP205 genome is longer than most single stranded RNA phages due to the presence of lengthy intercistronic regions, a long maturation gene, and two extra open reading frames before the maturation sequence.
Operator
The operator of AP205 contains a 4 nucleotide loop with adenosine at the first and last position with two other amino acids in between. This loop is typically present in the operator region of Fiersviridae. The AP205 operator region has a bulged adenosine on the hairpin structure similar to viruses in the Qubevirus genera. However, it is positioned closer to the 3' end of the hairpin structure.
Lytic gene
The first open reading frame (ORF) codes for a short lysis gene containing 35 amino acids. This gene is in a different position from the lytic genes of other viruses related to AP205. While other Fiersviridae encode their lytic genes between the coat and replicase proteins, AP205 has an open reading frame encoding a functional protein toward the 5' end of the genome that researchers suspect to have lytic function. The N-terminus of the gene consists of positively charged amino acids. The C-terminus consists of a group of non-polar amino acids. To confirm the function of the protein, researchers cloned the gene into a plasmid with a strong promoter. The plasmid was induced in E. coli, which resulted in limited cell growth when compared to the control. The enzymes encoded by the lysis protein do not disrupt the proton motive force of the host cell. This supports the theory that AP205 bacteriophage evolved and formed a lysis gene through utilizing a vacant area of the genome. The lytic protein of AP205 is produced in an efficient manner, and is used to lyse bacteria other than the host cell.
Maturation gene
Researchers suspect that the second open reading frame is involved in the translation of the maturation gene. Independent translation from the start codon of the second reading frame is suppressed by the lack of a strong Shine-Dalgarno sequence and a stable hairpin structure. The start codon of this ORF is within this strong hairpin secondary structure. The hairpin structure results in a translational rephrasing from the ORF2 reading frame to the A-protein (maturation protein) frame. The protein product of the maturation gene facilitates attachment of the bacteriophage to the host pilus through the cell attachment motif.
Coat protein gene
The third ORF codes for the coat protein. The coat protein of AP205 varies from other single stranded RNA phages due to the presence of a C-terminal β-strand that is not seen in evolutionarily related particles. In every other known single stranded RNA bacteriophage, the first twenty amino acid of the coat protein form two β-strands (strands A and B) that combine and yield a β-hairpin on the exterior surface of the viral particle. In AP205, the first β-strand (strand A) of the coat protein is located at the same position as the second strand (strand B) in other phages. However, the C-terminal strand (strand B) in AP205 coincides with the first strand (strand A). The termini connect via an amino acid linker and yield a dimer, which serves as the subunit for capsid assembly. When dimerized, the C-terminus of one coat protein monomer is located close to the N-terminus of the other. The AP205 coat protein transfers the N-terminal β-strand strand to the C-terminus to yield circular permutation of the capsid. The result of this conformation is a lack of an AB loop formed by Strand A and B. The topology of the AP205 coat protein dimer resembles the double sandwich model of other ssRNA phages. The helices of AP205 form a wide gap that is filled with large side chains. The wider gaps result from a long αA subunit and the wide angle of which the αB subunit is to the αA subunit and the β-sheet. The space provided by the gaps is utilized by bulky side chains. The coat protein follows the conserved folding pattern of Fiersviridae with the exception of β-hairpin formation at the N-terminus.
Replicase gene
The final ORF encodes the replicase gene. The protein product of this sequence yields a RNA-dependent RNA polymerase. The replicase gene is controlled by the same mechanism in all single stranded RNA bacteriophages. The start codon is folded into a hairpin structure with an affinity for the coat protein. However, in AP205 there is no binding of the coat protein to the translational operator of the replicase gene to repress translation.
Taxonomy
Single stranded RNA viruses are subject to higher levels of mutation when compared to other viruses, resulting in a diverse collection of genomic sequences. Single stranded RNA coliphages are classified into two genera: Qubevirus and Fiersviridae. AP205 shares characteristics with viruses in both of these genera (such as the Fiersviridae MS2 and the Quebevirus Qβ), and is phylogenetically classified between MS2 and Qβ. The operator region of displays identifying cahracteristics of both genera. The operator in AP205 has adenosine residues are in the same placement as those in Fiersviridae, but there is not a bulged adenosine at the same position of the hairpin loop in the operator. Viruses in the Quebevirus genera encode a coat extension protein, which the Fiersviridae genera lacks. AP205 does not contain this coat extension protein. AP205 has more genetic similarities to Fiersviridae, with the exception of the 3' UTR which has more similarities to a Quebevirus. There are many conserved sequences and motifs in AP205 that aide in the phylogenetic classification of the bacteriophage. The sequence UGCUU in the 3' untranslated region is preserved in all RNA coliphages, and is present in AP205. The RNA-dependent RNA polymerases of AP205 contain the conserved (Y)GGD motif present in other positive sense single stranded RNA bacteriophages.
Infection
Bacteriophage AP205 infects gram-negative bacteria by attaching to and adsorbing into the pilus of the Acinetobacterium. The maturation protein recognizes the pilin subunits of the host’s pilus. AP205 uses type IV twitching pili for attachment to the host cell. Once bound to the pilus, the virus releases its genome into the bacteria by cleaving the maturation/A protein. During the later stages of infection in single stranded RNAs, the coat protein will bind to an RNA hairpin structure preceding the replicase gene. AP205 is an exception, and does not experience this type of interaction. In other single stranded RNA phages, a high concentration of the coat protein results in the binding of a dimer to the hairpin loop, which blocks ribosomal access. This halts transcription of the replicase protein, and results in packaging of the replicated viral genome. Further research is necessary to determine the termination of replicase translation. After the coat proteins are produced, the capsid experiences self-assembly. Circular permutation exposes the exterior termini on the coat proteins, which cluster together through various interactions. Once assembled, the virus will lyse the cell via the product of the lytic gene. The single-gene lysis mechanism of AP205 is unknown. However, the product of the lysis gene‘ in many single stranded RNA bacteriophages does not have any peptidoglycan degradation ability.
Medical applications
Modular vaccine approach
The capsid of AP205 has 180 protein subunits. Each individual subunit can be fused to multiple peptides. Researchers have made an AP205 VLP with up to 370 peptides attached to the coat. The lack of an AB loop in AP205 provides an advantage to using the VLP in the development of vaccines. Peptide insertions to the area can destabilize the protein shell of the VLP and yield nonfunctional dimers. Bacteriophage AP205 has been used as a vector for delivering antigens in vaccines. The production of virus-like particles (VLP) derived from Bacteriophage AP205 can be used to display antigens that elicit an immune response in the target. Using a VLP as a vector for immunization does not pose a risk of transmitting disease due to the absence of a viral genome. AP205 serves as an attractive virus for this process due to its high tolerance for antigen fusion. The coat protein of an AP205 VLP can tolerate conjugation to many antigens due to the availability of both the N and C terminus. This availability of both termini is a limiting factor in the use of other VLPs in immunological studies. AP205 VLPs are also used in vaccine designs due to their ability to self-assemble with long epitopes up to 55 amino acids in length fused to the surface. These structures activate a strong humoral response through production of specific antibodies in the host [9]. Bacteriophage AP205 has been used in previous studies to produce vaccines-induced active active immunity against SARS-CoV-2, Influenza, West Nile Virus, HIV, and many other infectious viruses.
Influenza
Bacteriophage AP205 has been used to make vaccines for influenza. By fusing the M2e extracellular domain of the influenza virus to the capsid of a AP205 VLP, researchers have been able to produce vaccines described to have protected infected mice from a lethal dosage of influenza. Researchers have fused the consensus sequence of the antigenic influenza M2e protein to the N-terminus of the capsid protein of AP205 by using a linker sequence. The VLP was propagated in E. coli. The genomic content within the M2e-AP205 VLP may be contaminated with RNA from the E. coli which the VLPs were propagated in, leading to induction of various antibodies that were not induced against the M2e. Mice immunized with M2e-AP205 that contained RNA from E. coli displayed more protection when compared to the mice immunized with M2e-AP205 that did not contain the RNA. These results indicate that the RNA within the VLP plays a role in the immunity provided against influenza.
Angiotensin II Receptor Type 1
Researchers have used AP205 VLP to decrease blood pressure in hypertensive animal subjects. They produced a vaccine through conjugating the B cell epitope ATR001 to the AP205 capsid protein structure. The repetitive pattern of the ATR001 epitopes permitted the formation of immune complexes with IgM antibodies following exposure. In addition to activating humoral immunity in vivo, the ATR-AP205-001 vaccine resulted in enhanced differentiation of Tfh cells, leading to expression of proinflammatory cytokines such as IL-21. IL-21 is required for the activation of memory B cells that are specific to the ATR001 epitope. The ATR-AP205-001 vaccine resulted in a rapid humoral response initiated through the recruitment of dendritic cells, Tfh cells, and B cells with limited activation from regulatory T cells.
SARS-CoV-2
Research studies have concluded that Bacteriophage AP205-VLPs can be used to generate a vaccine against SARS-CoV-2. Using the coat proteins of AP205, researchers have been able to present the receptor binding domain of the SARS-CoV-2 spike protein to invoke an immune response in mice. A stable AP205 VLP was designed by using a linker to fuse 2 capsid proteins, then adding the receptor binding motif (RBM) domain of the SARS-CoV-2 spike to the C terminus of the AP205 dimer. The formation of this complex was confirmed via SDS-PAGE and Electron Microscopy analysis. Each dimer in the AP205 VLP incorporated a RBM domain, resulting in 90 RBM domains per VLP. Mice immunized with the AP205-RBM experienced an increase in IgA response, RBD and spike protein specific antibody production, and class switching to IgG2a and IgG1 antibodies that was not observed in the control subjects. Researchers have also used SpyCatcher to fuse the RBD proteins to the capsid of an AP205VLP. To form a RBD-CLP particle, researchers fused a peptide-binding Tag and a gene linker to the N-terminus AP205 coat protein, which was then cloned into the pET28a(+) vector. The plasmid was transformed into competent E. coli cells, and the subsequent Tag-CLP products were purified. Researchers fused receptor binding domain antigens with a GSGS linker and the split-protein Catcher, and combined this product with the Tag-CLP to form RBD-CLP complexes. Mice immunized with this complex displayed induction of IgG2a and IgG2b antibodies.
West Nile virus
Cross-linking an antigen to the surface of a AP205 VLP can increase the immunogenicity of the protein. Vaccines made via the conjugation of DIII to AP205 VLPs induced high titers of antibodies specific to DIII after a single injection when compared to the groups of mice who were immunized with free DIII-C proteins and non-conjugated AP205 particles. The repetitive pattern of DIII on the capsid results in efficient cross-linking of B-Cell Receptors and leads to a specific humoral response in the host. Antigen presenting cells uptake the VLP, present the DIII antigen epitopes on the MHC II receptor to activate T helper cells. Bacterial RNA packaged within the BLP enhances antigen-presenting cell activity when it is delivered to the endosomal compartment and activates TLR 3 and TLR7/8. The AP205 subunits that were cross-linked to DIII-C molecules displayed an average of 50 DIII molecules per particle due to the availability of both the N and C terminus on the coat protein. The immunogenicity of the AP205 vaccine proved to be higher than the previous vaccines. VLPs made in this experiment contained about 25-30 micrograms of host cell E. Coli RNA per 100 micrograms of coat protein. The antibodies produced act to neutralize the infectious West Nile Virus particles.
Other applications
Salmonid aquaculture
Bacteriophage AP2-5 can be used to target pathogenic bacterium in animals as well as human hosts. Bacteriophage AP205 can be used to vaccinate fish against A. salmonicida, a gram negative bacterium found in salmon with furunculosis. Research studies have used conjugated AP205 VLP-VapA to induce a strong antibody reaction in rainbow trout resulting in survival rates up to 44% higher than that of the control immunization.
Agriculture and waste water treatment
AP205 can be utilized as an indicator for microbial contaminants in water to reduce public health risks. While bacterial coliforms are usually used to determine contamination levels of water, viruses provide several advantages. Viruses are typically more resistant against UV radiation and other environmental stresses. AP205 shares a similar chemical composition and several physical characteristics similar to noroviruses and rotaviruses, allowing it to be used as a surrogate marker of contamination of crops by enteric viruses. AP205 is propagated in Acinetobacter baumannii, which can cause gastroenteritis in individuals who consume contaminated produce.
References
Bacteriophages
Riboviria | Bacteriophage AP205 | [
"Biology"
] | 4,024 | [
"Viruses",
"Riboviria"
] |
68,892,243 | https://en.wikipedia.org/wiki/Phosphanide | Phosphanides are chemicals containing the [PH2]− anion. This is also known as the phosphino anion or phosphido ligand. The IUPAC name can also be dihydridophosphate(1−).
It can occur as a group phosphanyl -PH2 in organic compounds or ligand called phosphanido, or dihydridophosphato(1−). A related substance has PH2−. Phosphinidene (PH) has phosphorus in a −1 oxidation state.
As a ligand PH2 can either bond to one atom or be in a μ2-bridged ligand across two metal atoms. With transition metals and actinides, bridging is likely unless the metal atom is mostly enclosed in a ligand.
In phosphanides, phosphorus is in the −3 oxidation state. When phosphanide is oxidised, the first step is phosphinite ([H2PO]−). Further oxidation yields phosphonite ([HPO2]2−) and phosphite ([PO3]3−).
The study of phosphine derivatives is unpopular, because they are unstable, poisonous and malodorous.
Formation
Alkali metal phosphanides can be made from phosphine and the metal dissolved in liquid ammonia. Sodium phosphanide can also be made from phosphine and triphenylmethyl sodium. Lithium phospahnide can be made from phosphine and butyl lithium or phenyl lithium.
Another way to produce -PH2 complexes is by hydrolysis of a -P(SiMe3)2 compound with an alcohol, such as methanol.
Yet another way is to remove a hydrogen atom from the phosphine in a phosphine complex by using a strong base.
Properties
When calcium phosphanide is heated, it decomposes by releasing phosphine and yielding the phosphanediide: CaPH. With further heating a binary calcium phosphide is formed. Other compounds may also lose hydrogen as well as phosphine.
Phosphanides can react with CCl4 to substitute Cl for H giving a -PCl2 compound. Similarly CBr4 can produce -PBr2. Also AgBF4 can react to yield -PF2.
Sodium phosphanide can react with ethyl alcohol in a diethyl carbonate solution to yield sodium 2-phosphaethynolate (NaOCP). Na(DME)2OCP is also formed from NaPH2 when reacted with CO in a dimethoxyethane (DME) solution under pressure.
List
Derivatives
Some derivatives of phosphanides have also been studied where hydrogen is substituted by another group. They include bis(trimethylsilyl)phosphanide, bis (triisopropylsilyl) phosphanide, bis (trimethylsilyl) phosphanide, diphenyl phosphanide.
References
Phosphines
Ligands | Phosphanide | [
"Chemistry"
] | 659 | [
"Ligands",
"Coordination chemistry"
] |
68,897,186 | https://en.wikipedia.org/wiki/Yang-Hui%20He | Yang-Hui He (; born 29 September 1975) is a mathematical physicist, who is a Fellow at the London Institute, which is based at the Royal Institution of Great Britain, as well as lecturer and former Fellow at Merton College, Oxford. He holds honorary positions as visiting professor of mathematics at City, University of London, Chang-Jiang Chair professor at Nankai University, and President of STEMM Global scientific society.
Yang works on the interface between quantum field theory, string theory, algebraic geometry and number theory, as well as how AI and machine-learning help with these problems. He is one of the pioneers of the field of using AI for pure mathematics.
Yang is author of over 200 scientific publications and is also a keen communicator of science, giving regular public lectures including the Royal Institution Friday Evening Discourse ,
as well as podcasts.
His other outreach activities include acting as an advisor to BMUCO and being a fellow of the One Garden.
Education and career
Yang received his A.B. in Physics from Princeton University in 1996, with Highest Honours (summa cum laude, Allen Shenstone Prize and Kusaka Memorial Prize), joint with certificates in applied mathematics and in engineering physics. He received his Masters from University of Cambridge in 1997 with Distinction and then obtained his PhD from MIT in 2002 in the Center for Theoretical Physics (NSF Scholarship and MIT Presidential Award) under the supervision of Amihay Hanany.
After postdoctoral work at the University of Pennsylvania, in the group of Burt Ovrut, Yang joined the University of Oxford as FitzJames Fellow and Advanced Fellow of the STFC, UK, working closely with Philip Candelas. He remains a tutor at Merton College, Oxford when taking up his professorships at the University of London and Nankai University, and more recently, when he joined the London Institute.
Works
Yang has authored over 200 journal papers, as well as several books, notably:
Topology and Physics, co-edited with C. N. Yang and Mo-Lin Ge, with contributions from Sir Michael Atiyah, Edward Witten, Sir Roger Penrose, Robbert Dijkgraaf et al., recommended by Book Authority as one of the 20 most influential books in quantum field theory of all time.
The Calabi-Yau Landscape: from geometry, to physics, to machine-learning, textbook aimed at early PhD students, introducing mathematics to physicists, physics to mathematicians and machine-learning to both, the first textbook on the AI mathematician.
Dialogues Between Physics and Mathematics: C. N. Yang at 100, co-edited with Mo-Lin Ge, with contributions from Edward Witten, Sir Roger Penrose, Sir Anthony James Leggett, Alexander Polyakov, Vladimir Drinfeld et al., celebrating the 100th birthday of C. N. Yang.
Machine Learning in Pure Mathematics and Theoretical Physics, the first of its kind, as a collection of essays on the interactions between AI and pure mathematics/fundamental physics.
References
External links
1975 births
Academics of the University of London
Academic staff of Nankai University
Mathematical physicists
Quantum physicists
Living people
Massachusetts Institute of Technology alumni | Yang-Hui He | [
"Physics"
] | 634 | [
"Quantum physicists",
"Quantum mechanics"
] |
68,897,666 | https://en.wikipedia.org/wiki/Icd-II%20ncRNA%20motif | The icd-II non-coding RNA (ncRNA) is an RNA motif proposed as a Strong Riboswitch Candidate (SRC). Icd-II ncRNA has been recognized by a comparative sequence analysis in GC-rich intergenic regions (IGR) of bacteria, using a pipeline call Discovery of Intergenic Motifs PipeLine (DIMPL). Icd-II ncRNA has been located upstream of the icd gene, which codes for an NADP+-dependent isocitrate dehydrogenase (IDH) enzyme. IDH is part of the citric acid cycle, and thus it participates in managing the carbon flux through this energy metabolism pathway. Icd-II ncRNA has been found in bacteria of the class beta proteobacteria, particularly in Polynucleobacter genus. Icd-II RNA secondary structure consists of a three-stem junction, where the ribosome binding site (RBS) of the adjacent open reading frame (ORF) is predicted to be involved in the first base-paired stem. It has been proposed that icd-II ncRNA can function as a riboswitch that regulates translation initiation of its associate ORF.
References
External links
Cis-regulatory RNA elements
Riboswitch | Icd-II ncRNA motif | [
"Chemistry"
] | 262 | [
"Biochemistry stubs",
"Molecular and cellular biology stubs"
] |
68,898,128 | https://en.wikipedia.org/wiki/Slice%20%28painting%29 | Slice is a 2020 oil painting by the American artist Jasper Johns.
The work is a horizontal, mostly black oil painting that contains references to two outside sources: an anatomical diagram of a knee drawn by a Cameroonian emigre student Jéan-Marc Togodgue; and a map of the distribution of galaxies in a slice of the universe by Valérie de Lapparent, Margaret Geller, and John Huchra with graphics by Michael J. Kurtz. The painting was shown publicly for the first time in September 2021 at the Whitney Museum of American Art in Johns's double museum retrospective Mind/Mirror, held simultaneously at the Whitney and the Philadelphia Museum of Art. The painting is currently a promised gift to the Museum of Modern Art, New York.
Much controversy has ensued over the fact that Johns initially used Togodgue's anatomical drawing of a knee without his knowledge. The artist informed the young student, who attended and played basketball at the Salisbury School near Johns's estate in Sharon, after Slice was completed. Johns originally saw the drawing in his orthopedist's office; Togodgue had given the drawing to the same doctor as a thank you for his own surgery. In August 2021, Johns and Togodgue reached an undisclosed settlement for a licensing agreement.
Johns received the image of the galaxies from astrophysicist Margaret Geller prior to executing the painting. The title Slice is taken from the concept that the map represents a slice of the universe.
References
2020 paintings
Paintings by Jasper Johns
Space art
Maps in art | Slice (painting) | [
"Astronomy"
] | 310 | [
"Space art",
"Outer space"
] |
68,898,978 | https://en.wikipedia.org/wiki/Kimito%20Funatsu | is a Japanese chemist specializing in chemoinformatics and data-driven chemistry, a Professor Emeritus at University of Tokyo, and the research director of the Data Science Center at Nara Institute of Science and Technology.
Biography
He graduated from Kagoshima Prefectural Konan High School in 1974 and from Department of Chemistry, School of Science, Kyushu University in 1978. He completed Department of Chemistry, Graduate School of Science, Kyushu University and obtained a doctorate in science in 1983. After he served as an Associate Professor at Toyohashi University of Technology, he became a Professor at Department of Chemical System Engineering, School of Engineering, University of Tokyo in 2004. He concurrently holds the posts of a Professor and the research director of the Data Science Center at Nara Institute of Science and Technology from 2017. He was also invited as visiting professor at University of Strasbourg in France in 2011.
The Division of Chemical Information of the American Chemical Society gave him the Herman Skolnik Award in 2019 for his contributions to structure elucidation, de novo structure generation and applications of cheminformatics methods to materials design and chemical process control. He also received the for 2020. In 2021, he retired from University of Tokyo at mandatory age and was given the title of Professor Emeritus.
References
1955 births
Living people
20th-century Japanese chemists
21st-century Japanese chemists
Cheminformatics
Academic staff of the University of Tokyo
Academic staff of Nara Institute of Science and Technology
Kyushu University alumni | Kimito Funatsu | [
"Chemistry"
] | 293 | [
"Computational chemistry",
"Cheminformatics",
"nan"
] |
68,899,895 | https://en.wikipedia.org/wiki/Microsoft%20Whiteboard | Microsoft Whiteboard is a free multi-platform application, as well as an online service and a feature in Microsoft Teams, which simulates a virtual whiteboard and enables real-time collaboration between users.
Overview and features
Microsoft Whiteboard allows users to draw on a virtual whiteboard using input methods such as a stylus pen or a mouse and keyboard, and write down notes, draw connections between shareable ideas and interact in real time. Microsoft Whiteboard is available to download on the following platforms and devices:
Microsoft Windows (on Windows 10 or above)
Android
Apple iOS
Surface Hub devices
It is also available on the web and as a feature in Microsoft Teams.
Microsoft Whiteboard allows users with Microsoft accounts to view, edit and share whiteboards using the provided tools and options. The feature set includes tools for drawing, shapes and media. Drawing in Microsoft Whiteboard is called inking. It works both on mobile devices and computers. The inking toolbar has customizable pencils, as well as a ruler, a highlighter, an eraser and an object selector. Whiteboard can recognize shapes drawn by hand and straighten them. Holding the Shift key on a computer while inking draws straight lines.
Microsoft Whiteboard has keyboard shortcuts for some functions.
Additional features include inserting sticky notes, text boxes, stickers, as well as images. Grid lines and colors are adjustable. There are different templates, which can be inserted into the whiteboard. Users can also share their reactions. A feature limited to boards created in Microsoft Teams, is the ability to make them read-only; other participants from the meeting cannot edit them.
Reviews
PC Magazine rated Microsoft Whiteboard a 3.5 out of 5, praising the app's free availability and plentiful templates. It compared it to other, paid whiteboarding solutions, and concludes that Microsoft offers the best free one. Some of the cons, described by PCMag, include the inability to view boards without a Microsoft account, and the inability to create custom templates.
See also
Whiteboarding
References
External links
Official website (Whiteboard web app)
Whiteboard for Android - Apps on Google Play
Whiteboard
Application software
Collaborative software
Computer-mediated communication
Android (operating system) software | Microsoft Whiteboard | [
"Technology"
] | 454 | [
"Computer-mediated communication",
"Information systems",
"Computing and society"
] |
68,901,004 | https://en.wikipedia.org/wiki/Experimental%20Techniques | Experimental Techniques is an official journal of the Society for Experimental Mechanics and was established in 1975. The journal is published by Springer Nature and the editor-in-chief is Bonnie Antoun (Sandia National Laboratories).
Abstracting and indexing
The journal is abstracted and indexed in:
According to the Journal Citation Reports, the journal has a 2020 impact factor of 1.167.
References
External links
English-language journals
Materials science journals
Springer Science+Business Media academic journals
Academic journals established in 1975
Bimonthly journals | Experimental Techniques | [
"Materials_science",
"Engineering"
] | 104 | [
"Materials science journals",
"Materials science"
] |
68,901,022 | https://en.wikipedia.org/wiki/Journal%20of%20Dynamic%20Behavior%20of%20Materials | The Journal of Dynamic Behavior of Materials is a quarterly peer-reviewed scientific journal published by Springer Science+Business Media on behalf of the Society for Experimental Mechanics. Jennifer L. Jordan (Los Alamos National Laboratory) has been the editor-in-chief since 2020. The journal was established in 2015 with Eric N. Brown as the inaugural editor-in-chief.
Abstracting and indexing
The journal is abstracted and indexed in:
Astrophysics Data System
Ei Compendex
Emerging Sources Citation Index
ProQuest databases
Scopus
References
External links
English-language journals
Materials science journals
Springer Science+Business Media academic journals
Academic journals established in 2015
Quarterly journals
Hybrid open access journals | Journal of Dynamic Behavior of Materials | [
"Materials_science",
"Engineering"
] | 136 | [
"Materials science journals",
"Materials science"
] |
68,903,729 | https://en.wikipedia.org/wiki/Topre | is a Japanese engineering company that manufactures stamped parts for automobiles, refrigeration units for trucks, air conditioners, and various other electronic and electro-mechanical equipment. It was founded in 1935 as Tokyo Press Kogyo Co. Ltd., in Kōtō, Tokyo.
History
Topre was founded in April 1935 as the Tokyo Press Kogyo Co. Ltd. with a capital of JP¥300,000. From the 1930s until around the mid-1970s, the company was focused on low-tech tool and die manufacturing. In 1958, it acquired Tokyo Die-Cast Co. Ltd. and within the next four years set up two die-cast plants in Kanagawa and Hiroshima.
In 1976, Tokyo Press Kogyo began a venture into electronics with keyboards for computer terminals. The first several of their prototype designs were unsuccessful with technology companies within Japan being reluctant to order them into production. In the late 1970s, a young engineer inspired by the katori senkō—a Japanese mosquito coil—devised a conical-spring capacitive key switch which held promise with the company's executives. After half a year of perfecting the design and another half a year of rigorous life-cycle testing, TPK took their keyboards to the Japanese market, earning orders from Hitachi, JVC, Ricoh, and others.
In 1981, TPK tasked salesperson Seiji Miwa, who set up an American office for the company three years prior, to market the design in the United States. There he was able to win accounts for NCR and Memorex, who respectively ordered 1,500 and 10,000 units of their keyboard. In October that year, the company changed its name to Topre, promoting Miwa to executive managing director of Topre's new Research and Development subsidiary.
By 1985, its Tokyo manufacturing plant was producing 30,000 units a month. At up to US$90 per keyboard (equivalent to $ in ) in 1985, Topre's keyboards were costlier than others, which along with its overseas manufacturing put the company's ability to compete with other keyboard manufacturers in the United States into question at the time. Topre's capacitive key switches are still being manufactured for some Japanese keyboards, most notably the Happy Hacking Keyboard, as well as Topre's own Realforce. Albeit still costly, with Computer Shopper calling the Realforce too bland otherwise to justify the high price, keyboards with Topre switches are renowned by keyboard enthusiasts for their tactile feel, with David Hayward of Micro Mart calling the Realforce the "Aston Martin One-77 of the keyboard world."
Topre was a manufacturer of bumpers and dashboards for Nissan, Isuzu, and Honda automobiles in the 1990s. In June 2000, Topre gained Toyota as a client and started construction of a ¥2.5 billion plant in Fukuoka Prefecture for the manufacturing of pressed parts for Nissan and Toyota. Their automotive manufacturing division made the move to the United States in 2005, with the opening of a plant in Cullman, Alabama, with a budget of $132 million. They set up shop in Nissan's factory in Smyrna, Tennessee, in 2012 as a small operation, later moving to their own factory in the city in 2015, purchasing an additional 35 acres of factory space in 2019. In 2014, Topre moved their production of Nissan parts closer to the aforementioned company's factory in Canton, Mississippi, while retaining their Cullman plant. They also have an automotive parts factory in Springfield, Ohio.
Topre's long-standing chairman Kyohei Ishii died in 2018.
References
External links
(in )
(in )
Official website of Topre America Corporation
Auto parts suppliers of Japan
Computer companies of Japan
Computer hardware companies
Computer peripheral companies
Electrical engineering companies of Japan
Japanese companies established in 1935
Manufacturing companies based in Tokyo
Companies listed on the Tokyo Stock Exchange | Topre | [
"Technology"
] | 796 | [
"Computer hardware companies",
"Computers"
] |
68,903,743 | https://en.wikipedia.org/wiki/Smoke%20control | In the event of a fire, a smoke control system is used to keep a building's escape routes and access routes free from smoke, assist fire-fighting operations and delay or prevent flashover, thereby reducing the risk that the fire will escalate.
In the United Kingdom, the Smoke Control Association operates as a professional and advisory organisation in this field.
Standards
Within the International Organization for Standardization (ISO), Technical Committee ISO/TC 21/SC 11 is responsible for the development of standards concerned with smoke and heat control systems and components.
In Australia and New Zealand, joint standard AS/NZS 1668.1:2015 aims to provide: Requirements for the maintenance of smoke control systems fall outside this standard.
References
Smoke
Fire protection | Smoke control | [
"Engineering"
] | 150 | [
"Building engineering",
"Fire protection"
] |
68,904,876 | https://en.wikipedia.org/wiki/Ovarian%20culture | Ovarian culture is an in-vitro process that allows for the investigation of the development, toxicology and pathology of the ovary. This technique can also be used to study possible applications of fertility treatments e.g. isolating oocytes from primordial ovarian follicles that could be used for fertilisation.
Culture methods using mouse ovarian tissue
There are several culture systems which can be employed to investigate ovarian and follicular growth and development.
Whole ovarian culture
The culture of intact ovaries supports the formation and development of primordial follicles. Ovaries are dissected from neonatal mouse pups and placed into ovarian culture medium containing Bovine Serum Albumen (BSA) dissolved in α-Minimal Essential Media (αMEM). The cultures are maintained in a 37°C, 5% CO2 incubator and then the ovaries are frozen or fixed to facilitate further study.
Follicle culture
Individual
This method of culturing supports the growth of individual follicles from late pre-antral to pre-ovulatory stage. This system allows follicle growth and hormone production to be studied. The ovaries of young mice (19–23 days) are removed and halved, and follicles are identified under a microscope. Late pre-antral follicles are identified as having a diameter of 180-200 μm and containing 2-3 layers of granulosa cells. Follicles are manually dissected and then examined for suitability to culture. Follicles are chosen for culture only if they are healthy (diameter of 190 ± 10 μm; translucent; without dark atretic areas; intact basal lamina.) Wells containing follicle culture medium (α-Minimal Essential Media, recombinant human follicle stimulating hormone, ascorbic acid and adult female mouse serum) is overlaid with sterilised silicon oil, which prevents medium evaporation. A follicle is placed at the bottom of each well and maintained in a 37°C, 5% CO2 incubator, being moved into a well containing fresh medium for up to 6 days. If growth measurements are being taken visually the distortion due to the oil layer must be accounted for. Follicles are frozen or fixed so further analysis can be performed.
Paired
By culturing 2 follicles in close proximity, follicle-follicle interactions can be examined. The follicles may grow together to form a two-follicle unit. The follicles are dissected from the ovaries as above, then placed in contact with each other in pairs, in a well with follicle culture medium and sterilised silicon oil. Follicles from different genetic sources can be co-cultured so that tissue origins can be differentiated within the co-culture. The medium is replaced every 2 days and after 6 days the culture is fixed or frozen for further processing.
Follicle-ovary co-culture
This method allows follicle-ovary interactions to be studied. The ovaries and follicles are dissected as above and then one follicle is placed in contact with one pole of a neonatal ovary on a plate. The follicle-ovary plate is cultured in follicle culture medium at 37 °C, 5% CO2 for up to 5 days. At this point the co-culture is frozen or fixed before further processing. To facilitate differentiation between tissue origins the ovary and the follicle should be from different genetic sources.
Uses of ovarian culture techniques
Toxicological studies
At present research within the field of reproductive toxicology is principally carried out in vivo, however new culture methods have been developed with the aim of allowing ovarian follicles to be grown in vitro. These new methods allow us to culture isolated ovarian follicles, embryos, ovaries (whole organ or only part of the tissue), and embryonic stem cells. Ovarian cultures are useful to research as they can allow us to replicate systematic follicle development, periodical ovulation, and follicle atresia in an environment with modulated culture conditions.The ability of in vitro ovarian cultures to detect damage to the ovary and its specialised structures of the follicles and oocytes, allows for faster screening of potential developmental and/or reproductive toxicants. Therefore, ovarian culture systems have become increasingly widely used in reproductive biology and toxicology.
Culture of the whole ovary or ovarian fragments allows evaluation of various parameters in a controlled way and, therefore, has the potential for more complete reproductive toxicity studies. A big advantage of ovarian culture is the ability to evaluate the effect of drugs on the pool of primordial follicles that make up the ovarian reserve. However, this strategy is restricted regarding the duration of culture time, as short periods may not be sufficient to ensure follicular development. On the contrary, cells may be negatively affected by longer periods of culture.
Most in vitro toxicology studies use female mice and rat models. These species have been selected to assess the adverse effects of drugs on reproductive function and fertility, due to ease of handling and small size. Additionally, these species have been well characterised; anatomically, physiologically, and genetically. Their short life cycles make it convenient to assess gestation, breastfeeding, and puberty. The relevance of animal studies for toxicological risk assessment in heterogeneous human populations remains undetermined as it is unknown if the results obtained can be extrapolated to humans.
Fertility treatment
The use of in vivo maturation in ovarian culture would eliminate the risk of Ovarian Hyperstimulation Syndrome during IVF in patients with polycystic ovary syndrome (PCOS). For those without PCOS, in vitro maturation still has advantages as the process is less intense as superovulation is not required. Principles of ovarian culture can be applied to women who are resistant to FSH or oestrogen sensitive tumours. In comparison to IVF, cells used in vitro maturation are harvested at a smaller size, immature and arrested at Metaphase I stage of meiosis. Once in the lab they undergo maturation to Metaphase II.
Fertility preservation
Ovarian tissue can be harvested before ovarian damaging treatments and re-implanted at a later stage using cryopreservation. However, this method is associated with the recurrence of malignancy in those with ovarian cancer and leukaemia. In theory, ovarian tissue culture is a safer method to produce mature oocytes for fertilisation in these patients.
References
External links
In vitro fertilisation
Cell culture
Reproduction
Fertility medicine
Environmental toxicology | Ovarian culture | [
"Biology",
"Environmental_science"
] | 1,411 | [
"Behavior",
"Toxicology",
"Reproduction",
"Biological interactions",
"Environmental toxicology",
"Model organisms",
"Cell culture"
] |
68,905,054 | https://en.wikipedia.org/wiki/Benjamin%20List | Benjamin List (; born 11 January 1968) is a German chemist who is one of the directors of the Max Planck Institute for Coal Research and professor of organic chemistry at the University of Cologne. He co-developed organocatalysis, a method of accelerating chemical reactions and making them more efficient. He shared the 2021 Nobel Prize in Chemistry with David MacMillan "for the development of asymmetric organocatalysis".
Background
Born to an upper-middle-class family of scientists and artists in Frankfurt, List is a great-grandson of the cardiologist Franz Volhard and a 2nd great-grandson of the chemist Jacob Volhard. His aunt, the 1995 Nobel laureate in medicine Christiane Nüsslein-Volhard, is the sister of his mother, architect Heidi List. At age three, his parents divorced.
Career and research
List obtained his Diplom (M.Sc.) degree in chemistry from the Free University of Berlin in 1993, and his PhD from Goethe University Frankfurt in 1997. His doctoral dissertation was titled Synthese eines Vitamin B 12 Semicorrins (Synthesis of a Vitamin B 12 Semicorrin), and was advised by Johann Mulzer. List worked at the Scripps Research Institute Department of Molecular Biology in La Jolla, US as a postdoctoral researcher in Carlos F. Barbas III and Richard Lerner's research groups from 1997 to 1998 with a scholarship from the Alexander von Humboldt Foundation and as an assistant professor from 1999 to 2003.
In 2003 he returned to Germany to become group leader at the Max Planck Institute for Coal Research, and in 2005 he became one of the institute's directors, heading the Homogeneous Catalysis Department. He served as the institute's managing director from 2012 to 2014. He has held a part-time position as an honorary professor of organic chemistry at the University of Cologne since 2004. List is also a principal investigator at the Institute for Chemical Reaction Design and Discovery, Hokkaido University since 2018. He is the editor-in-chief of the scientific journal Synlett. , he has an h-index of 95 according to Google Scholar and of 86 according to Scopus.
List is considered to be one of the founders of organocatalysis, which uses non-metal and non-enzyme catalysts. In particular, while still an assistant professor he discovered the possibility of using the amino acid proline as an efficient chiral catalyst. This takes place in intermolecular aldol reactions, in which carbon atoms from two different molecules are bonded together, induced by proline. The development is based on the Hajos–Parrish–Eder–Sauer–Wiechert reaction. Subsequently, he developed the first proline-catalyzed Mannich, Michael, and α-amination reactions. He found asymmetric catalysis (especially Asymmetric counteranion directed catalysis, ACDC). He developed also new methods of textile organic catalysis, in which soluble organic catalysts and textiles are bound. These methods could, for example, help to treat water where there is no fresh water. Asymmetric organocatalysis is particularly important in bioactive organic compounds, where the chirality of the compounds is important, for example in drug production.
On 6 October 2021, he was awarded the Nobel Prize in Chemistry with David MacMillan "for the development of asymmetric organocatalysis." The development has great influence on pharmaceutical research and the drug production and "made chemistry greener".
Personal life
List married Sabine List in La Jolla in 1999 and they have two sons, Theo and Paul. They all survived the 2004 Indian Ocean earthquake and tsunami.
List's parents sought to raise their children with an anti-authoritarian parenting style; he has admitted occasionally using the approach with his own children, stating that "you may only be 12, but if you think it will do you good to eat ten chocolate bars, then go ahead and do it. I have faith in you. But my advice is: I wouldn't do it."
Honors and awards
Source:
1994 NaFöG-Award from the City of Berlin
1997 Feodor Lynen Fellowship of the Alexander von Humboldt Foundation
2000 Synthesis-Synlett Journal Award
2003 of the German Chemical Society
2004 Degussa Prize for Chiral Chemistry
2004 Lecturer's Award of the Fonds der Chemischen Industrie
2004 Lieseberg Prize of the University of Heidelberg
2005 AstraZeneca European Lectureship, the Society of Synthetic Chemistry, Japan
2005 Lectureship Award
2005 Novartis Young Investigator Award
2006 JSPS Fellowship Award of Japan
2007 AstraZeneca Award in Organic Chemistry
2007 Award of the Fonds der Chemischen Industrie
2007 OBC-Lecture Award
2008 Visiting Professor at Sungkyunkwan University, Korea
2009 Boehringer-Ingelheim Lectureship, Canada
2009 Organic Reactions Lectureship, US
2009 Thomson Reuters Citation Laureate
2011 Boehringer-Ingelheim Lectureship, Harvard University, US
2011 ERC Advanced Grant
2012 Novartis Chemistry Lectureship Award
2012 Otto Bayer Award
2013 Horst-Pracejus-Preis
2013 Mukaiyama Award
2013 Ruhrpreis, Mülheim, Germany
2014 Cope Scholar Award, US
2014 Thomson Reuters Highly Cited Researcher
2015 Carl Shipp Marvel Lectures, University of Illinois at Urbana-Champaign, US
2016 Gottfried Wilhelm Leibniz Prize
2017 Prof. U. R. Ghatak Endowment Lecture, Indian Association for the Cultivation of Science (IACS), Kolkata, India
2017 Ta-shue Chou Lectureship, Institute of Chemistry, Academia Sinica, Taipei, Taiwan
2018 Member of the German National Academy of Sciences Leopoldina
2019 Herbert C. Brown Lecture, Purdue University, Indiana, US
2019 Web of Science Citation Laureate in Chemistry
2021 TCR Lecture, 100th CSJ Annual Meeting, Japan
2021 Nobel Prize in Chemistry
2022 Herbert C. Brown Award 2022 for Creative Research in Synthetic Methodes
2024 John Stauffer Distinguished Lecture in the Sciences University of Southern California
2024 Criegee Lectureship (Karlsruhe Institute of Technology)
Selected works
Source:
References
Further reading
External links
1968 births
20th-century German chemists
21st-century German chemists
Living people
Free University of Berlin alumni
German Nobel laureates
Goethe University Frankfurt alumni
Gottfried Wilhelm Leibniz Prize winners
Members of the German National Academy of Sciences Leopoldina
Nobel laureates in Chemistry
German organic chemists
Scientists from Frankfurt
Max Planck Institute directors
Academic staff of the University of Cologne
Max Planck Society people | Benjamin List | [
"Chemistry"
] | 1,320 | [
"Organic chemists",
"German organic chemists"
] |
68,905,567 | https://en.wikipedia.org/wiki/Circumtriple%20planet | A circumtriple planet is a celestial mass that is hypothesized to be orbiting not only a single star but three stars at the same time. Scientists observing the star system GW Ori, which is a huge disk of dust and gases about 1,300 light years away from Earth, suspect that there may be a circumtriple planet orbiting the three stars. They observed a gap in the vast dust cloud and they hypothesize that there may be a planet in this gap. The planet itself has not been seen but its influence may explain gravitational oddities within the star system. By using computer modeling, some scientists believe that a Jupiter-sized planet may be able to explain the star system's rings and strange behavior, according to one account. If so, this may be the first known example of a circumtriple planet in the universe.
In 2022, evidence of a very small planet was found around the triple system PSR J0337+1715. In 2024, additional data allowed the planet's mass to be constrained to , making it one of the smallest objects directly detected outside the Solar System so far.
In 2024, the substellar object CWISE J235827.96–521813.4 was detected to be bound to the Gliese 900 triple star system at a distance of , thus becoming the planet with the longest orbital period and first confirmed circumtriple planet.
Circumtriple planets are likely to be an extremely rare phenomenon in the universe. Studying them could add to human understanding of how planets form.
Fiction
A circumtriple planet is prominently featured in the Remembrance of Earth's Past book series. In the series, the planet of Trisolaris orbits a three-star system, and the chaotic nature of the system drives the native species of the planet to seek refuge on Earth, which has a comparatively more "stable" one-star system.
References
Further reading
GW Ori: circumtriple rings and planets, Jeremy L. Smallwood, Rebecca Nealon, Cheng Chen, Rebecca G. Martin, Jiaqing Bi, Ruobing Dong, Christophe Pinte, 20 Sep 2021
Astronomical hypotheses | Circumtriple planet | [
"Astronomy"
] | 460 | [
"Astronomical hypotheses",
"Astronomical controversies"
] |
68,905,874 | https://en.wikipedia.org/wiki/Khayyam%20%28play%29 | "Khayyam" () is a tragedy written by the Azerbaijani playwright Huseyn Javid, in 1935. It was dedicated to the famous poet and thinker Omar Khayyam, and was firstly published in 1963 in Baku. It was staged in March 1970 at the Azerbaijan Drama Theatre in Baku.
Play’s history
Huseyn Javid wrote the play "Khayyam" in 1935. In the same year, it was awarded the 3rd place in the competition of literary works of the Azerbaijan SSR.
Huseyn Javid once sent the play to his friend who lived in Yerevan. After a long time, in 1957, his daughter, Turan Javid, managed to find it in Yerevan and bring it to Baku.
The play was firstly published in 1963 by the Azerneshr publishing house in Baku.
On 12 March 1970, the play was staged in the Azerbaijan State Academic Drama Theatre named after M. Azizbekov by the Peoples Artist of the USSR, the Professor Mekhti Mammadov. The decoration of the performance and sketches were prepared by the artist Elchin Mammadov, and the music was written by the Peoples Artist of the Azerbaijan SSR, the laureate of the USSR State Prize - Jahangir Jahangirov. The roles were played by Mekhti Mamadov, Shafiga Mamedova, Hasanagha Turabov, Mamedrza Sheikhzamanov, Ismayil Osmanli, and others.
See also
Siyavush
The Devil
Sheikh Sanan
References
Plays set in Azerbaijan
1935 plays
Historical plays
Tragedy plays
Tragedies of Huseyn Javid
Works about Omar Khayyam
Azerbaijani-language plays
Cultural depictions of Omar Khayyam | Khayyam (play) | [
"Astronomy"
] | 350 | [
"Cultural depictions of Omar Khayyam",
"Cultural depictions of astronomers"
] |
68,906,231 | https://en.wikipedia.org/wiki/List%20of%20Mersenne%20primes%20and%20perfect%20numbers | Mersenne primes and perfect numbers are two deeply interlinked types of natural numbers in number theory. Mersenne primes, named after the friar Marin Mersenne, are prime numbers that can be expressed as for some positive integer . For example, is a Mersenne prime as it is a prime number and is expressible as . The exponents corresponding to Mersenne primes must themselves be prime, although the vast majority of primes do not lead to Mersenne primes—for example, .
Perfect numbers are natural numbers that equal the sum of their positive proper divisors, which are divisors excluding the number itself. So, is a perfect number because the proper divisors of are , and , and .
Euclid proved that every prime expressed as has a corresponding perfect number . For example, the Mersenne prime leads to the corresponding perfect number . In 1747, Leonhard Euler completed what is now called the Euclid–Euler theorem, showing that these are the only even perfect numbers. As a result, there is a one-to-one correspondence between Mersenne primes and even perfect numbers, so a list of one can be converted into a list of the other.
It is currently an open problem whether there are infinitely many Mersenne primes and even perfect numbers. The density of Mersenne primes is the subject of the Lenstra–Pomerance–Wagstaff conjecture, which states that the expected number of Mersenne primes less than some given is , where is Euler's number, is Euler's constant, and is the natural logarithm. It is widely believed, but not proven, that no odd perfect numbers exist; numerous restrictive conditions have been proven, including a lower bound of .
The following is a list of all 52 currently known () Mersenne primes and corresponding perfect numbers, along with their exponents . The largest 18 of these have been discovered by the distributed computing project Great Internet Mersenne Prime Search, or GIMPS; their discoverers are listed as "GIMPS / name", where the name is the person who supplied the computer that made the discovery. New Mersenne primes are found using the Lucas–Lehmer test (LLT), a primality test for Mersenne primes that is efficient for binary computers. Due to this efficiency, the largest known prime number has often been a Mersenne prime.
All possible exponents up to the 48th () have been tested and verified by GIMPS . Ranks 49 and up are provisional, and may change in the unlikely event that additional primes are discovered between the currently listed ones. Later entries are extremely long, so only the first and last six digits of each number are shown, along with the number of decimal digits.
Notes
References
External links
List on GIMPS, with the full values of large numbers
A technical report on the history of Mersenne numbers, by Guy Haworth
Mathematical tables
Primes
List
List | List of Mersenne primes and perfect numbers | [
"Mathematics"
] | 624 | [
"Perfect numbers",
"Mathematical tables",
"Number theory"
] |
71,878,784 | https://en.wikipedia.org/wiki/Seizo%20Onoe | Seizo Onoe, a Japanese telecommunication executive, is the Director of the Telecommunication Standardization Bureau of the International Telecommunication Union, the Secretariat of ITU-T. Onoe was elected to the post of Director of the TSB for the term 2023-2026 at the ITU Plenipotentiary Conference 2022 (PP-22).
Career
Prior to being elected, Onoe had a career with Japanese mobile operator NTT DOCOMO for over thirty years. As of 2021, he served as Executive Vice President and Chief Standardization Strategy Officer for the Nippon Telegraph and Telephone (NTT) Corporation as well as simultaneously a Fellow of NTT DOCOMO.
Between 2017 and 2021, he served as NTT DOCOMO’s Chief Technology Architect as well as President of the DOCOMO Technology subsidiary.
From 2012 until 2017, Onoe held the position of Chief Technology Officer and Executive Vice President, (Member of the Board of Directors and Managing Director of R&D Innovation Division) at NTT DOCOMO. Prior to this, he served as Senior Vice President and Managing Director of NTT DOCOMO’s R&D Strategy Department and Managing Director of the company’s Radio Network Development Department.
Studies
Seizo Onoe holds Master’s and Bachelor's degrees in Electrical Engineering from the Kyoto University (Graduate School of Engineering).
Personal life
Mr. Onoe is married and has two children.
References
International Telecommunication Union
International Telecommunication Union people
Living people
1957 births
People from Akashi, Hyōgo
NTT Docomo
Kyoto University alumni | Seizo Onoe | [
"Technology"
] | 313 | [
"Members of the Conexus Mobile Alliance",
"NTT Docomo"
] |
71,879,783 | https://en.wikipedia.org/wiki/Rumina%20Velshi | Rumina Velshi (born c.1955) is the former Canadian President and Chief Executive Officer of the Canadian Nuclear Safety Commission (CNSC). She chaired a committee for International Gender Champions. She became a partner in a nuclear company.
Life
Velshi was born in Uganda and she had parents who had Indian heritage. In 1972, Idi Amin who was the President of Uganda decided to eject Ugandan Asians from the country. She and her parents had to leave and they went to Canada. She arrived early in the year and later that year she had to decide on a university course. Velshi has noted that when she was evicted from Uganda she had one significant possession and that was her education. She was a student interested in maths and physics so a course in Engineering beckoned. She liked the description of the Civil Engineering course and she enrolled. During the first lecture she realised that she was one of three women students among about 100 students in the course. She graduated in 1978 and her first job was with Ontario Hydro.
Velshi joined the Canadian Nuclear Safety Commission in 2011. and she won the 2011 Women in Nuclear (WiN) Canada Leadership Award in that year.
In 2018, Velshi became the President and CEO of the CNSC.
Velshi has been keen to encourage other women to choose a career in a STEM subject. She is the vice-chair of "Scientists in School" which organises opportunities for 700,000 Canadian school children to attend science workshops.
In 2020, she took on an international role for the IAEA becoming their Chairperson for their Commission on Safety Standards.
In 2024 she was a partner in ZettaJoule, Inc. who plan to build small nuclear reactors.
References
1950s births
Living people
Civil engineers
Ugandan women engineers
University of Toronto alumni
Ugandan refugees
Canadian businesspeople
Nuclear engineers | Rumina Velshi | [
"Engineering"
] | 376 | [
"Civil engineering",
"Civil engineers"
] |
71,880,389 | https://en.wikipedia.org/wiki/Hemoglycin | Hemoglycin (previously termed hemolithin) is a space polymer that is the first polymer of amino acids found in meteorites.
Structure
Structural work has determined that its 1,494 Dalton core unit (Glycine18 / Hydroxy-glycine4 / Fe2O4) contains iron, but not lithium, leading to the more general term hemoglycin for these molecules. The hemoglycin core contains a total of 22 glycine residues in an anti-parallel beta sheet chain that is terminated at each end by an iron atom plus two oxygens. Four of these glycine residues are oxidized to hydroxy-glycine with hydroxy groups (-OH) on the alpha carbon. This structure was determined by mass spectrometry of meteoritic solvent extracts and has been confirmed in X-ray scattering by crystals of hemoglycin, and also by optical absorption. Crystals show a 480 nm characteristic absorption that can only exist when hydroxy-glycine residues have R chirality and are C-terminal bonded to iron.
History
Because hemoglycin has now been found to be the dominant polymer of amino acids in 6 different meteorites (Allende, Acfer 086, Efremovka, Kaba, Orgueil and Sutter's Mill), each time with the same structure, it has been proposed that it is produced by a process of template replication. The measured 480 nm absorbance is larger than expected for a racemic distribution of R and S chirality in the hydroxy-glycine residues, indicating an R chirality excess in the polymer. Modeling of template replication that is assumed to depend on 480 nm absorption leads to an excess of R chirality and thus is consistent with this finding.
Significance
Hemoglycin is a completely abiotic molecule that forms in molecular clouds which go on to become protoplanetary disks, long before biochemistry on exoplanets like Earth begins. Hemoglycin via its glycine could seed an exoplanet (one able to support early biochemistry), but its main function appears to be the accretion of matter via formation of an extensive low-density lattice in space in a protoplanetary disk. Besides being present in carbonaceous meteorites, hemoglycin has also been extracted and crystallized from a fossil stromatolite that formed on Earth 2.1 billion years ago. Potentially this fossil hemoglycin was delivered to Earth during the Late Heavy Bombardment (LHB). Data to support this is that the hemoglycin in the fossil has extraterrestrial isotopes similar to that in meteorites.
The polymer on the precambrian Earth could have driven the Great Oxygenation Event (GOE) beginning 2.4 Gya by splitting water in response to ultraviolet irradiation. Also, it could have provided an energy source to early biochemistry and/or it could have simply delivered a source of polymer glycine.
A comment from the Harvard research leader on Hemoglycin JEMMc - Hemoglycin, a space polymer of glycine and iron has been extensively characterized [1-11] and now needs to be considered in the context of 4 areas of astronomy and planetary science:
1st in astronomy, the period between Pop III and Pop II stars, when the constituent elements of hemoglycin first formed even as early as 500My into cosmic time [1].
2nd in molecular clouds and protoplanetary disks where the polymer is likely to form and function in accretion [6,9,10]. Thus, the polymer could be a major player in solar system formation throughout the Universe.
3rd after in-fall to planets like Earth, where on Earth it could have kick-started the “The Great Oxygenation Event” (GOE) [9].
4th on exo-planets that evolve biochemistry like Earth, it could be asked whether the formation of DNA involves hemoglycin as a template. Guanine and cytosine nucleotide bases could form and bind to the 5nm glycine rods of in-fall hemoglycin to start the coding of glycine [12].
Hemoglycin is not a biological molecule, being outside of biochemistry, that is, abiotic. It may have first formed 500 million years into cosmic time as a structure that could absorb photons from 0.2-15µm [7,8,9,10], be available throughout the Universe, and provide energy to drive adjacent space chemistry. On its in-fall to exo-planets like Earth it could absorb solar ultraviolet and donate energy to early chemical systems. Hemoglycin could therefore be thought of as an abiotic absorber of light, a supplier of energy and an accretor of matter.
Synthetic hemoglycin synthesis will be attempted in 2025 to aid acquisition of a refined x-ray diffraction set for its structure. Hemoglycin crystals from meteorites, and stromatolites, to date are fiber-like or multiple [6,8,9]. A comparison of the MALDI mass spectrometry fragmentation patterns [5,11] of synthetic and extracted hemoglycin will be informative.
1. McGeoch J. E. M. and McGeoch M. W. (2014) Polymer Amide as an Early Topology. PLoS ONE 9(7): e103036. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0103036
2. McGeoch J. E. M. and McGeoch M. W. (2015) Polymer amide in the Allende and Murchison meteorites. Meteoritics & Planetary Science 50, Nr12 1971-1983. https://onlinelibrary.wiley.com/doi/10.1111/maps.12558
3. McGeoch J. E. M. and McGeoch M. W. (2017) A 4641Da polymer of amino acids in Acfer-086 and Allende meteorites. https://arxiv.org/pdf/1707.09080.pdf
4. McGeoch M. W., Šamoril T., Zapotok D. and McGeoch J. E. M. (2018) Polymer amide as a carrier of 15N in Allende and Acfer 086 meteorites. https://arxiv.org/abs/1811.06578.
5. McGeoch M. W., Dikler S. and McGeoch J. E. M. (2021) Meteoritic Proteins with Glycine, Iron and Lithium https://arxiv.org/abs/2102.10700. [physics.chem-ph]
6. McGeoch J. E. M. and McGeoch M.W. (2021) Structural Organization of Space Polymers. Physics of Fluids 33, 6, June 29th. https://aip.scitation.org/doi/10.1063/5.0054860.
7. McGeoch J. E. M. and McGeoch M. W. (2022) Chiral 480nm absorption in the hemoglycin space polymer: a possible link to replication. Sci. Rept. 12 16198 DOI: 10.1038/s41598-022-21043-4 License CC BY 4.0
8. McGeoch M. W., Owen R., Jaho S. and McGeoch J. E. M. (2023) Hemoglycin visible fluorescence induced by X-rays. J. Chem. Phys. 158, 114901 (2023); https://doi.org/10.1063/5.0143945
9. McGeoch J. E. M., Frommelt A. J., Owen R., Cinque G., McClelland A., Lageson D. and McGeoch M. W. (2024) Fossil and present-day stromatolite ooids contain a meteoritic polymer of glycine and iron. Int. J. Astrobiology 23, e20, 1-21 https://doi.org/10.1017/S1473550424000168 & arXiv:2309.17195 [physics.geo-ph].
10. McGeoch J. E. M. and McGeoch M. W. (2024) Polymer amide as a source of the cosmic 6.2 micron emission and absorption arXiv:2309.14914 [astro-ph.GA]. Mon. Not. Roy. Astron. Soc. 530, 1163-1170. DOI: https://doi.org/10.1093/mnras/stae756.
11. McGeoch J. E. M and McGeoch M. W. (2024) Sea foam contains hemoglycin from cosmic dust. RSC Advances, 2024, 14, 36919 – 36929. https://doi.org/10.1039/d4ra06881e
12. Lei L. and Burton Z. F. (2021) Evolution of the genetic code, Transcription, 12:1, 28-53, DOI: 10.1080/21541264.2021.1927652
See also
Ancient protein
Bubble (physics)
Earliest known life forms
Evolutionary history of life
Extraterrestrial: The First Sign of Intelligent Life Beyond Earth
List of interstellar and circumstellar molecules
Panspermia
Protein
References
Astrobiology
Biological hypotheses
Iron compounds
Origin of life
Panspermia
Prebiotic chemistry
Proteins | Hemoglycin | [
"Chemistry",
"Astronomy",
"Biology"
] | 2,078 | [
"Biomolecules by chemical classification",
"Origin of life",
"Panspermia",
"Speculative evolution",
"Prebiotic chemistry",
"Astrobiology",
"Molecular biology",
"Biological hypotheses",
"Proteins",
"Astronomical sub-disciplines"
] |
71,881,271 | https://en.wikipedia.org/wiki/Maya%20%28wolf%29 | Maya (Chinese: ) is a cloned female arctic wolf that was born from a beagle surrogate mother in China. She was born on June 10, 2022, and news of her birth was revealed to the public on September 19 of the same year at Harbin Polarland, in China's Heilongjiang Province, by the biotechnology company Sinogene.
Genesis and birth
Maya was cloned in a Beijing lab using skin cells from a 16-year-old female donor arctic wolf, also named Maya, that was living in Harbin Polarland, an arctic theme-park in China. A skin cell from the donor wolf was inserted into the enucleated egg cell of a female beagle, whereby the somatic nucleus from the skin cell and the recipient oocyte were reconstituted into a new embryo. This method was performed in order to construct 137 new embryos. Scientists then inserted 85 of the embryos into seven different beagle surrogate mothers. The experiments resulted in failed births six out of seven times, with Maya being the only wolf born successfully. Although she was born on 10 June 2022, researchers decided to wait 100 days before unveiling her to the public due to the high likelihood that she would die young. Researchers said that it would be impossible to release her into the wild due to her lack of socialization with other wolves for the beginning of her life. She was then moved to Harbin Polarland where she now lives with her beagle surrogate mother.
Implications for conservation
Although arctic wolves are not under threat, the researchers behind Maya hope that the genetic technology used can potentially help other species under threat as the world heads into an extinction crisis. Sinogene, the company behind Maya, said that it will be working with the Beijing Wildlife Park to research more applications for the cloning of rare and endangered animals in China.
See also
List of animals that have been cloned
References
Cloned animals
2022 animal births
2022 in China
Individual animals in China
Individual wolves | Maya (wolf) | [
"Biology"
] | 410 | [
"Cloning",
"Cloned animals"
] |
71,881,497 | https://en.wikipedia.org/wiki/Arsaalkyne | In chemistry, an arsaalkyne is chemical compound with a triple bond between carbon and arsenic. These organoarsenic compounds are rare, especially in comparison with the phosphaalkynes. The parent HCAs has been characterized spectroscopically, otherwise the only arsaalkynes have bulky organic substituents.
Synthesis and isolation
Arsaalkynes are produced by dehydrohalogenation or related base-induced elimination reactions. The case of HCAs is illustrative:
Owing to the principles of the double bond rule, arsaalkynes tend to oligomerize more readily than the phosphorus analogues. Thus attempts to prepare AsCCMe3 produce the tetramer, which has a cubane structure. The very bulky substituent C6H2-2,4,6-(t-Bu)3 does however allow the crystallization of the monomeric arsaalkyne. Its As-C bond length is 1.657(7) Å.
See also
Cyaarside
References
Functional groups
Organoarsenic compounds | Arsaalkyne | [
"Chemistry"
] | 224 | [
"Functional groups"
] |
71,881,524 | https://en.wikipedia.org/wiki/BE%20Ursae%20Majoris | BE Ursae Majoris is a binary star system in the northern circumpolar constellation of Ursa Major, abbreviated BE UMa. The two components are an unusual M-class dwarf star and a subdwarf O star, borderline white dwarf. It is classified as a detached Algol variable and ranges in brightness from an apparent visual magnitude of 14.8 down to 17.8. This is too faint to be visible to the naked eye. The distance to this system is approximately 4,600 light years based on parallax measurements.
The variability of SVS 1424 was announced in 1964 by N. E. Kurochkin from Sternberg, and was found to have a period of 2.291 days while ranging in brightness from magnitude 14.1 down to 15.6. After being assigned the variable star designation BE UMa, it was discovered to be a source of hot ultraviolet emission with a helium-rich spectrum by D. H. Ferguson and associates in 1981. B. Margon and associates found variability of spectral features on a time scale as low as a few hours. They interpreted this as a detached binary system consisting of a compact, high temperature white dwarf and a cool red dwarf star. The outer layers of the cooler star are being ionized by radiation from the hotter component, and the changing orientation of this heated region over the course of an orbit is creating a sinusoidal variability of about 1.5 magnitudes.
In 1982, a deep eclipse was discovered in the light curve by H. Ando and associates. This put a strong limit on the possible models for the system, which indicated that the compact component is a hot O-type subdwarf. D. Crampton and associates in 1983 found that the temperature and radius of the cool component suggested that it is an evolved subgiant star. At present, no mass transfer is taking place, but the system appears to be evolving into a cataclysmic variable as the subdwarf cools to become a normal white dwarf.
In 1995, J. Liebert and associates discovered that the system is surrounded by a planetary nebula with a diameter of , which was likely shed when the present day subdwarf was leaving the asymptotic giant branch stage. The two components would have shared a common envelope as little as 10,000 years ago. As a result, rather than being a subgiant, the cool component has not yet reached the thermal equilibrium of a late dwarf star. The pair have a circular orbit with a period of 2.2911658 days and a separation of . The orbital plane is inclined at an angle of to the line of sight from the Earth.
References
Further reading
M-type main-sequence stars
O-type subdwarfs
White dwarfs
Algol variables
Ursa Major
Ursae Majoris, BE | BE Ursae Majoris | [
"Astronomy"
] | 582 | [
"Ursa Major",
"Constellations"
] |
71,881,584 | https://en.wikipedia.org/wiki/List%20of%20organisms%20with%20names%20derived%20from%20Indigenous%20languages%20of%20the%20Americas | This list includes organisms whose common or scientific names are drawn from indigenous languages of the Americas. When the common name of the organism in English derives from an indigenous language of the Americas, it is given first.
In biological nomenclature, organisms receive scientific names, which are formally in Latin, but may be drawn from any language and many have incorporated words from indigenous language of the Americas. These scientific names are generally formally published in peer-reviewed journal articles or larger monographs along with descriptions of the named taxa and ways to distinguish them from other taxa.
List
References
indigenous
Taxonomy (biology)
Taxonomic lists
Indigenous languages of the Americas | List of organisms with names derived from Indigenous languages of the Americas | [
"Biology"
] | 124 | [
"Lists of biota",
"Taxonomy (biology)",
"Taxonomic lists"
] |
71,881,589 | https://en.wikipedia.org/wiki/Eleanor%20Janega | Eleanor Janega is an American broadcaster and medievalist. Her scholarship focuses on gender and sexuality; apocalyptic thought; propaganda; and the urban experience, in the late medieval period.
Biography
Despite her initial interest in pursuing Chinese history in college, particularly the 17th century transition from the Ming Dynasty to the Qing dynasty, upon encountering professors Barbara Rosenwein and Theresa Gross-Diaz at Loyola University Chicago, she says, "It was over," and her career studying Medieval history had begun.
Janega gained her undergraduate degree in History (with honours) from Loyola University Chicago, and holds an MA (with distinction) in Medieval Studies and a PhD in history, both from University College London. Her doctoral thesis on the 14th-century Bohemian preacher Milíč of Kroměříž was titled Jan Milíč of Kroměříž and Emperor Charles IV: Preaching, Power, and the Church of Prague, and was supervised by Martyn Rady.
She is a guest teacher in the London School of Economics Department of International History, and teaches a standalone online course on Medieval Gender and Sexuality.
Janega co-hosts the Going Medieval documentary strand on the History Hit streaming service. She also co-hosts the Gone Medieval podcast, and has appeared as a talking head on radio and television.
Selected publications
References
External links
Eleanor Janega
Going Medieval
Living people
1982 births
21st-century American historians
21st-century American non-fiction writers
21st-century American women writers
Loyola University Chicago alumni
Alumni of University College London
Academics of the London School of Economics
American broadcasters
American medievalists
American history podcasters
Historians of the Czech Republic
Women's historians
Women's studies academics
Historians of sexuality
Urban historians
American expatriates in England | Eleanor Janega | [
"Biology"
] | 341 | [
"Behavior",
"Sexuality",
"Historians of sexuality"
] |
71,881,949 | https://en.wikipedia.org/wiki/Hamus%20%28archaea%29 | Archaea, one of the three domains of life, are a highly diverse group of prokaryotes that include a number of extremophiles. One of these extremophiles has given rise to a highly complex new appendage known as the hamus (: hami). In contrast to the well-studied prokaryotic appendages pili and fimbriae, much is yet to be discovered about archaeal appendages such as hami. Appendages serve multiple functions for cells and are often involved in attachment, horizontal conjugation, and movement. The unique appendage was discovered at the same time as the unique community of archaea that produces them. Research into the structure of hami suggests their main function aids in attachment and biofilm formation. This is accomplished due to their evenly placed prickles, helical structure, and barbed end. These appendages are heat and acid resistant, aiding in the cell's ability to live in extreme environments.
Archaeal background
In 1977, archaea, then known as archaebacteria, were first discovered when Carl Woese and George Fox published their findings in the Proceedings of the National Academy of Sciences, stating that these organisms were distantly related to bacteria. This revolutionized biology into the three domains of life known today; Bacteria, Eukarya, and Archaea. By checking the ratios of biogenic isotopes that are unique to different metabolisms, scientists have dated archaea as far back as 2,500 million years. Due to oxygen being a trace element in the atmosphere at this time, archaea anaerobes methanotrophy is believed to have preceded bacterial aerobic methanotrophy. When studying phylogenetic trees, Bacteria are evolved from the last universal common ancestor or LUCA, while Archaea and Eukarya are considered sister lineages because they share a last common ancestor that is more recent than LUCA.
Hami function
Archaea, much like other microorganisms, possess a variety of extracellular appendages to facilitate important functions such as motility, cell adhesion, and DNA transfer. Unlike fimbriae and pili, whose composition and function(s) are well defined among bacterial species, hami belong to a relatively new class of filamentous cell appendages unique to archaea. Archaeal cells may have as many as 100 hami, which are largely composed of 120 kDa subunits. Each hamus (hami plural), is helical in shape with many hook-like projections at the distal end, which are hypothesized to aid in attachment to surfaces within the environment, or in the formation of biofilms.
Hami producers
Archaeal cells possessing hami appear to grow only in relatively cold aquatic environments around 10 degrees Celsius, which could be suggestive of a particular function that has not yet been defined. One possible explanation for this observation could be the relationship archaeal cells, SM1 euryarchaeon, possessing hami have with Thiothrix, a type of sulfur-oxidizing bacterium typically found within similar conditions. Hamus-bearing archaeal cells sometimes form macroscopically visible communities with Thiothrix or IMB1 ε- proteobacterium, called a string-of-pearls. Thiothrix and IMB1 ε- proteobacterium are filamentous bacteria that appear to form the outer shell of the pearl as well as the strings that connect these pearls together. Within the pearls, it appears the archaea SM1 euryarchaeon forms the majority of the core. Research has shown the SM1 euryarchaeon use the hamus to aid in biofilm formation. The formation of string-of-pearls communities suggests a mutual dependency for nutrient exchange, though the entirety of this unique relationship has yet to be established. Another hami producing biofilm was discovered that was dissimilar from the string pearl formation. This biofilm consists almost entirely of SM1 archaea making it the first biofilm found of this nature as no other biofilm with a nearly pure composition of archaea has been found. This biofilm has a highly organized structure with distances between cells being exceptionally consistent. Scientists speculate the hami are not only responsible for the strong attachments found in the biofilm formation but also this highly intricate and specific structure. It is possible that other archaeal cells possessing hami have not yet been discovered or cultured.
Hami special abilities
Archaeal appendages serve a variety of purposes and provide the archaeal cells with multiple unique and essential abilities. Hami play a large role in cellular attachment. These appendages allow the cells to adhere to each other, as well as their surroundings. When the hami filaments of one cell come into contact with a neighboring cell, the hami are able to entangle and produce a web like structure between the cells. This helps to form and maintain the biofilm. Hami are also used by the cells in biofilms or individually to adhere to external environmental surfaces. They have been proven to attach to substances with varying chemical compositions including those of an inorganic nature. Hami are also capable of contributing to the EPS of the cell as part of the main protein component of the EPS.
One interesting facet of these hami is that their 120 kDa protein allows them to remain stable over a broad range of temperatures. One research experiment found hami to be stable at 70 degrees C and noted the finding curious as the only currently known hami producing cells live in 10 degrees C. These hami were also noted to be stable over a significant pH range of 0.5-11.5. Archaea are known as extremophiles and live in extreme environments, but this capacity to remain stable over a large range of both pH and temperature makes hami very unique structures. Similarly, this lends to the possibility that archaeal hami may exist in other yet to be discovered biofilms outside of the 10 degree C temperature range and in various pH ranges.
References
Prokaryotes | Hamus (archaea) | [
"Biology"
] | 1,268 | [
"Archaea",
"Archaea biology",
"Molecular biology stubs",
"Molecular biology"
] |
71,882,263 | https://en.wikipedia.org/wiki/Niobium%28V%29%20oxynitrate | Niobium(V) oxynitrate is an inorganic compound with the proposed formula NbO(NO3)3. A single publication claims that niobium(V) oxynitrate is produced by the reaction of niobium pentachloride and dinitrogen pentoxide at 30 °C:
Nitryl chloride is produced as a byproduct.
Attempts failed to produce niobium(V) oxynitrate by the reaction dinitrogen tetroxide and niobium pentachloride in acetonitrile in the formation of the acetonitrile niobium dioxide nitrate complex.
References
Niobium(V) compounds
Nitrates | Niobium(V) oxynitrate | [
"Chemistry"
] | 146 | [
"Oxidizing agents",
"Nitrates",
"Salts"
] |
71,882,273 | https://en.wikipedia.org/wiki/Ya-Jun%20Pan | Ya-Jun Pan is a Chinese and Canadian mechanical engineer whose research involves robust and nonlinear control for teleoperation and multi-agent systems. She is a professor of mechanical engineering at Dalhousie University, where she directs the Advanced Control and Mechatronics Laboratory.
Education and career
Pan studied mechanical engineering at Yanshan University, graduating in 1996. After earning a master's degree in mechanical engineering at Zhejiang University in 1999, she completed a Ph.D. in electrical and computer engineering at the National University of Singapore in 2003.
Before becoming a faculty member at Dalhousie, she was a postdoctoral researcher in France with CNRS at the Laboratoire d'automatique de Grenoble, and in Canada at the University of Alberta.
Recognition
Pan was named as an ASME Fellow in 2017. In 2021 she was elected as a Fellow of the Engineering Institute of Canada, as "an internationally renowned expert in robust nonlinear control and networked control systems with successful in-depth applications to tele-robotics, cooperative systems, unmanned systems, industrial automation, and rehabilitations".
References
External links
Home page
Year of birth missing (living people)
Living people
Canadian mechanical engineers
Canadian women engineers
Chinese mechanical engineers
Chinese women engineers
Control theorists
Yanshan University alumni
Zhejiang University alumni
National University of Singapore alumni
Academic staff of Dalhousie University
Fellows of the American Society of Mechanical Engineers | Ya-Jun Pan | [
"Engineering"
] | 280 | [
"Control engineering",
"Control theorists"
] |
71,882,510 | https://en.wikipedia.org/wiki/Gerard%20Kraus | Gerard Kraus (February 25, 19201990) - was a Phillips Petroleum scientist known for developing testing standards for carbon black surface area.
Education
Kraus was born in Prague, Czechoslovakia, the son of a pathologist and professor of medicine. He came to the United States in 1940, following his graduation in 1938 from the State High School in Prague. In 1943, he completed his Bachelor of Science degree with High Honors from Southern Methodist University. He presented work entitled "Supercharging Diesels" at the ASME convention that year. In 1947, he received the doctoral degree in polymer chemistry working under W. B. Reynolds at the University of Cincinnati, under a fellowship funded by the Inland Division of General Motors Corporation. He studied adhesion of rubber-to-metal interfaces with application to the manufacture of tank track treads.
Career
From 1947 to 1953, Kraus was employed on the faculty at the University of Cincinnati, first as an instructor, then later as an assistant professor. He joined the Research and Development department at Phillips Petroleum Company in 1953. By 1963, he was managing a group responsible for exploratory work in carbon black, filler reinforcement, and properties of elastomers. In 1968 his title was Senior Scientist.
Kraus' most cited work is an account of the swelling behavior of filler-reinforced, vulcanized rubbers. He established a relationship on the assumption that, at the filler interface, swelling is completely restricted due to adhesion. He is also known for a model of the Payne effect.
Awards
1990 - Melvin Mooney Distinguished Technology Award
1996 - elected to the International Rubber Science Hall of Fame
References
1920 births
1990 deaths
Polymer scientists and engineers
20th-century American engineers
People from Bartlesville, Oklahoma | Gerard Kraus | [
"Chemistry",
"Materials_science"
] | 355 | [
"Polymer scientists and engineers",
"Physical chemists",
"Polymer chemistry"
] |
71,882,587 | https://en.wikipedia.org/wiki/Undecaprenyl%20phosphate | Undecaprenyl phosphate (UP), also known lipid-P, bactoprenol and C55-P., is a molecule with the primary function of trafficking polysaccharides across the cell membrane, largely contributing to the overall structure of the cell wall in Gram-positive bacteria. In some situations, UP can also be utilized to carry other cell-wall polysaccharides, but UP is the designated lipid carrier for peptidoglycan. During the process of carrying the peptidoglycan across the cell membrane, N-acetylglucosamine and N-acetylmuramic acid are linked to UP on the cytoplasmic side of the membrane before being carried across. UP works in a cycle of phosphorylation and dephosphorylation as the lipid carrier gets used, recycled, and reacts with undecaprenyl phosphate. This type of synthesis is referred to as de novo synthesis where a complex molecule is created from simpler molecules as opposed to a complete recycle of the entire structure.
The synthesis of UP differs between Gram-negative and Gram-positive bacteria. In Gram-positive bacteria, undecaprenol is found in vast quantities, which is then phosphorylated into UP. For Gram-negative bacteria however, there has yet to be any indication that they contain any undecaprenol at all. Instead of having an undecaprenol be phosphorylated, it appears that instead, Gram-negative bacteria undergo a dephosphorylation of undecaprenyl diphosphate which is catalyzed by both a type-2 phosphatidic acid, phosphatase homologue, and a BacA homologue.
Undecaprenyl phosphate is also known to be the "Universal Glycan Lipid Carrier". When UP is inhibited, the peptidoglycan synthesis is interrupted and it could lead to cell lysis. Furthermore, UP is involved in the metabolism of many cellular processes that can potentially be targeted by antibiotics. Also, it is common for bacteria to use UP to translocate glycan; however, certain bacteria do not use undecaprenyl phosphate as a glycan translocator.
Biosynthetic processes
Peptidoglycan synthesis
UP is involved in transporting peptidoglycan subunits from the cytoplasmic face of the cell membrane to the periplasmic or extracellular surface.
In the process, UP (also called lipid-P) complexes with UDP-N-acetylmuramic acid pentapeptide (UDP-NAM pentapeptide) to form lipid I, displacing UMP. From there, lipid I complexes with N-acetyl glucosamine (NAG) to form lipid II. Lipid II then is flipped across the membrane by a flippase to the outside leaflet of the cell membrane. The NAG-NAM pentapeptide subunit is then added onto the growing peptidoglycan chain, leaving behind undecaprenyl diphosphate. The extra phosphate on undecaprenyl diphosphate is cleaved by a pyrophosphatase and UP is then recycled to the cytoplasmic face of the cell membrane.
O-antigen synthesis in lipopolysaccharide assembly
UP also serves as the lipid transporter for the O-antigen component of lipopolysaccharide. It is supposed that sugars are assembled into O-antigen subunits directly on UP on the cytoplasmic surface of the cell membrane. Then the UP-O-antigen subunit gets flipped to the other side of the membrane, where similar UP-O-antigen subunits interact and aggregate the O-antigen subunits into repeating-subunit chains, leaving undecaprenyl diphosphate behind. Again undecaprenyl phosphate is recycled by a pyrophosphatase and flipped to the cytoplasmic face again.
Inhibition
UP is a valuable transporter for cell wall equipment. That being said, the components necessary for the proper UP functioning can be inhibited, restricting the aiding of cell wall synthesis. As a result, the bacteria's structure is compromised, and its ability to combat lysing is lost. On a larger scale, this is helpful when fighting, or preventing bacterial infections.
Bacitracin is an example of one of these antibiotics. It is a generic topical cream used for "cuts, scrapes, and burns", possessing "bacteriostatic and bactericidal properties". The process is accomplished by targeting and inhibiting the enzyme used to renew UP—membrane-bound undecaprenyl phosphatase hydrolyzing undecaprenyl diphosphate to UP. This renewal process is crucial for maintaining the flow of lipid I and lipid II across the membrane, and without it, the cell wall synthesis process is halted.
Clomifene, a medication used to treat infertility in women, is another UP inhibitor discovered in the last decade. It has a similar process of cell wall disruption as bacitracin, resulting with lysis of cells.
While Bacitracin and clomiphene are not the only inhibitors out there, they are two on the evolving list that have been experimentally proven to inhibit pyrophosphatase.
References
Phosphates | Undecaprenyl phosphate | [
"Chemistry"
] | 1,138 | [
"Phosphates",
"Salts"
] |
71,883,121 | https://en.wikipedia.org/wiki/Floral%20morphology | In botany, floral morphology is the study of the diversity of forms and structures presented by the flower, which, by definition, is a branch of limited growth that bears the modified leaves responsible for reproduction and protection of the gametes, called floral pieces.
Fertile leaves or sporophylls carry sporangiums, which will produce male and female gametes and therefore are responsible for producing the next generation of plants. The sterile leaves are modified leaves whose function is to protect the fertile parts or to attract pollinators. The branch of the flower that joins the floral parts to the stem is a shaft called the pedicel, which normally dilates at the top to form the receptacle in which the various floral parts are inserted.
All spermatophytes ("seed plants") possess flowers as defined here (in a broad sense), but the internal organization of the flower is very different in the two main groups of spermatophytes: living gymnosperms and angiosperms. Gymnosperms may possess flowers that are gathered in strobili, or the flower itself may be a strobilus of fertile leaves. Instead, a typical angiosperm flower possesses verticils or ordered whorls that, from the outside in, are composed first of sterile parts, commonly called sepals (if their main function is protective) and petals (if their main function is to attract pollinators), and then the fertile parts, with reproductive function, which are composed of verticils or whorls of stamens (which carry the male gametes) and finally carpels (which enclose the female gametes).
The arrangement of the floral parts on the axis, the presence or absence of one or more floral parts, the size, the pigmentation and the relative arrangement of the floral parts are responsible for the existence of a great variety of flower types. Such diversity is particularly important in phylogenetic and taxonomic studies of angiosperms. The evolutionary interpretation of the different flower types takes into account aspects of the adaptation of floral structure, particularly those related to pollination, fruit and seed dispersal and of protection against predators of reproductive structures.
Arrangement of the floral pieces
Depending on the family considered, the pieces of the flower can be arranged on the receptacle in two different ways. In the case of the spiral arrangement, the parts are inserted consecutively and at different levels, describing a spiral on the axis in the same way as the leaves are inserted on the stem. Examples of species with spiral flowers are Magnolia grandiflora (magnoliaceae), Victoria cruziana (nymphaeaceae) and Opuntia ficus-indica (cactaceae). In the case of the whorled or cyclic arrangement, the pieces are inserted at various nodes of the axis, arranged in whorls or cycles. Each floral piece of a whorl alternates with the pieces of the following whorl, for example, the petals alternate with the sepals. In these flowers, called cyclic or whorled, the number of whorls may vary, depending—again—on the family considered. Very often the flowers have four cycles (called tetracyclic), such as those of Solanum (Solanaceae), which show a cycle of sepals, one of petals, another of stamens and the last of carpels. Also common are pentacyclic flowers (bearing five cycles), since in this case they have two cycles of stamens instead of only one, such as the flowers of Lilium (liliaceae). Finally, there are many other cases in which the flowers have several whorls of stamens, as in Poncirus trifoliata (Rutaceae), in which case the flowers have more than five cycles.
Floral symmetry
An object is said to have symmetry when at least one plane can divide it into two parts, so that each part is the mirror image of the other. Spiral flowers have no plane of symmetry and are said to be asymmetrical or irregular, as in the case of Liriodendron tulipifera (magnoliaceae). However, in the whorled flowers, because there are repetitions of floral parts, there may be one or more planes of symmetry, so they can have bilateral symmetry (i.e., a single plane of symmetry) or radial symmetry (i.e., several planes can divide the flower in as many mirror images). Thus, two types of flowers can be distinguished by their symmetry. The flowers called actinomorphics, radiate or polysymmetric have radial symmetry, as is the case of Tulipa gesneriana (liliaceae) or Linum usitatissimum (linaceae). In contrast, monosymmetrical, dorsiventral or zygomorphic flowers have bilateral symmetry and the evolution of their shape is related to the need to attract and guide pollinators to them, as for example, the flowers of orchids and many legumes.
Perianth and perigonium
The perianth is the flower structure comprising the two sterile whorls, the calyx and the corolla. In many cases, as for example in weeping willow (Salix babylonica, salicaceae) or European ash (Fraxinus excelsior, oleaceae) the perianth may be missing, that is, the flowers have only the fertile whorls (androecium and gynoecium) and are called aperianthous, aclamyds or simply "naked" flowers. The flowers that present perianth—the most frequent case—are called perianthed, chlamydeous or "clothed".
In the perianth flowers may be the case that only present calyx, so they are called monoclamyds or, more usually, apetalous and the most conspicuous example is the urticaceae family. The absence of petals in these flowers should not lead to the assumption that they are not showy, since there are cases in which the sepals (called "petaloid sepals") acquire the consistency, shape and coloring of petals, as for example in the species of the genus Clematis (buttercups).
When perianth flowers have both calyx and corolla they are called dichlamydeous. The members of both whorls may differ from each other in shape and color and the flowers are said to be heteroclamydeous, as for example rose (Rose sp., rosaceae). When, on the other hand, the calyx and corolla parts are indistinguishable from each other in shape and color, the flower is called homochlamydeous. In this type of flowers, typical of many families of monocotyledons such as iridaceae and amaryllidaceae, the perianth is called perigonium and the pieces that compose it are called tepals. If the tepals resemble a petal the perigonium is called corollaceous (from corolla), and if they resemble sepals the perigonium is called calyceal (from calyx).
In a bud or flower bud, the relative arrangement of the sepals or petals of each flower whorl is called vernation. This arrangement must be observed in the flower bud because in the fully open flower the floral parts are often so far separated from each other that the vernation cannot be determined. There are six main types of vernation. In the valvar vernation, the flower pieces may touch each other at the edges, but without any of them being placed above or below the immediate ones; in the contorta each one mounts on the one following it and is overlapped by the one preceding it; in the quincuncial, there are two totally external pieces, two totally internal and the fifth piece is external at one edge and internal at the other. In the imbricate vernation, there is an external piece on both edges, another, contiguous to the previous one, totally internal, and the remaining three are external on one edge and internal on the other. The vexillary vernation is a variant of the preceding one, with the totally internal piece contiguous to the external one, which occupies a superior position. Finally, in the carinal vernation, the external piece of the vexillary preflowering becomes internal and one of the lower pieces becomes external. The vernation is important in the description and identification of plants because it often characterizes the different families. Thus, malvaceae have valvar vernation, gentianaceae, contorta; and in legumes, vexillary and carinal vernation are characteristic.
Calyx
The calyx is the outermost whorl of the flower. It has a protective function and is constituted by the sepals, generally of green color. If the sepals are free from each other the calyx is called dialisepalus, while if they are united it is called gamosepalus as in the carnation (Dianthus caryophyllus, caryophyllaceae) or the kapok (Erythrina crista-galli (legumes).
When the calyx is gamosepalous, three well-defined parts can be distinguished: the tube, which is the portion in which the sepals are united; the throat, which is the place where the sepals are separated from each other; and the limbo, which is the free portion, formed by the apical ends of each sepal or lobes.
The sepals can have varied consistency and shape. In the compositae, for example, the sepals are reduced to hairs or bristles that constitute the pappus.
Depending on its duration with respect to the other floral parts, the calyx may be ephemeral or fleeting, when the sepals fall when the flower opens, as in the poppy (Papaver rhoeas, Papaveraceae); deciduous, when the sepals are shed after fertilization has occurred; or persistent when it remains after fertilization and accompanies the fruit, as in the apple tree (Malus domestica, rosaceae).
The sepals can form spurs that carry nectar (they are called nectar spurs) to attract pollinators as occurs in Viola and Tropaeolum. In other species as for example in Impatiens balsamina, some of the calyx pieces acquire the shape and coloration of petals and, for that reason, they are adjectivized as petaloids.
Corolla
The corolla is the inner whorl of the perianth and the one that surrounds the fertile whorls of the flower. It is composed of petals, which are generally larger than the sepals and are colored. Each petal consists of a claw that fixes it to the receptacle and a blade or limb which is the widest and most showy part. The claw can be very short, as in roses or very long as in carnations (Dianthus). The blade can be very varied in shape, color and margin.
In certain genera—Narcissus, for example—at the top of the claw there is a ligular appendage that forms a cup inside the tepal cycle called paraperigonium or "false corolla". In other cases—Hymenocallis—the paraperigonium is constituted by a membrane that joins the filaments of the stamen together. In the latter case the paraperigonium is also called the "staminal corona".
If the petals are free from each other, the corolla is called dialipetalous. If, instead, they are joined through their margins, the corolla is called gamopetalous and, as in the case of the calyx, it has tube, throat and limb.
The shape of the gamopetalous corolla can be very varied: tubulose (cylinder-shaped, as in the central flowers of the capitula of the compositae family), infundibuliform (funnel-shaped, as in sweet potato, Ipomoea batatas, convolvulaceae); bell-shaped (like an inflated, bell-like tube, as in thrush, Convallaria majalis, ruscaceae), hypocrateriform (shaped like a long, slender tube, as in Jasminum), labiated (with the blade formed by two unequal segments, as in Salvia splendens, a lamiaceae), ligulated (with the tongue-shaped blade, which is seen in the peripheral flowers of the capitula of many compositae) and spurred (when it has one or more nectariferous spurs, as in Aquilegia).
The anatomy of the tepals and petals is similar to that of the sepals. The epidermal cell walls are often convex or papillose, especially on the adaxial side. In many petals, such as those of Brassica napus, the papillae are conical, with a marked cuticular thickening at the apex, and radial striations toward the base. It has been suggested that these thickenings allow an even diffusion of the emerging light, so that the brightness of the petals is uniform at any angle of illumination. Some epidermal cells of the petals are osmophores, containing essential oils that impart the characteristic fragrance to the flowers. The mesophyll usually has no chlorophyll parenchyma, but fundamental parenchyma.
The color of the petals results from the presence of pigments. In many flowers the cells have chromoplasts with caroteneid pigments (red, orange, yellow). The most important pigments are the flavonoids, mainly anthocyanins, which are dissolved in the cytoplasm of the cell; the basic pigments are pelargonidin (red), cyanidin (violet), and delphinidin (blue), flavonols (yellow to ivory). The color of anthocyanin pigments depends on the acidity (of the pH) of the cell juice: in Brunfelsia australis ("mountain lily") the flowers are purplish but as they age they turn white due to a change in pH.
The white color of many flowers, such as Magnolia grandiflora, is due to the phenomenon of total reflection of light. The petals may have air spaces in subepidermal position or a layer of cells with abundant starch grains, and in both cases the light is reflected. The dark colors are due to a total absorption of light operated by complementary pigments. In the black cultivars of "tulip" (Tulipa gesneriana) there is blue anthocyanin in the epidermal cells and yellow carotene in the subepidermal cells.
In some species the basal parts of the petals contain a flavonolglucoside called chalcone, which absorbs ultraviolet light, turning them into "nectar guides" for pollinating insects. This particular color, visible only to insects, is called bee purple.
Androecium
The androecium is one of the fertile cycles of flowers. The parts that make up the androecium are called stamens whose function is the generation of male gametophytes or pollen grains. The stamens are highly modified leaves formed by a foot that is inserted into the receptacle of the flower, called filament, and a distal portion called anther. The filament is the sterile part of the stamen, it can be very long, short or missing, in which case the anthers are called sessile. It is usually filiform, but may be thick, even petaloid, and may be provided with appendages. The anther is the fertile part of the stamen and usually consists of two distinguishable, contiguous parts, called thecae, joined by an area called the connective, which is also where the anther joins the filament. It is usually formed by two thecae, sometimes it can be constituted by a single theca as in malvaceae and cannaceae or by three in the case of Megatritheca (sterculiaceae). If the anther is cut perpendicular to its axis, it is observed that each anther contains one or two pollen sacs extending along its entire length.
After the maturation of the pollen grains, dehiscence or opening of the anther occurs to let the pollen out. The tissue responsible is called endothecium. If the opening occurs along the entire length of the septum separating the pollen sacs, the dehiscence is longitudinal, which is the most frequent case. In other cases, the endothecium is located in limited areas that later arise as valves or windows: poricidal dehiscence (as in Solanaceae) there is no endothecium, the destruction of the tissue at the apex of the anther occurs and pores are formed through which the pollen will come out.
The number of stamens in each flower is a highly variable character. Some species of the euphorbiaceae family have flowers with only one stamen (they are called monanders), the oleaceae have two stamens (flowers dianders) and in the myrtaceae there are numerous (they are polyanders). The number of stamens may or may not be equal to the number of petals. Thus, the flower is said to be isostomous if it has the same number of stamens as petals (as can be seen in the liliaceae and amaryllidaceae); anisostomous if the number of petals is different from the number of stamens (for example, in the genus Brassica, there are four petals and 6 stamens); diplostemone, when the number of stamens is twice the number of petals (the genus Kalanchoe, for example, has four petals and eight stamens) and it is polystemone when the number of stamens is more than twice the number of petals (as in Poncirus, with five petals and numerous stamens).
Many times the flowers have a reduced perianth and the stamens are long and showy. In these cases the function of attracting pollinators is fulfilled by the androecium. This type of flowers is usually arranged in inflorescences that, because of their shape, look like brushes or pipe cleaners, as for example in the leguminous plants Inga uruguensis and Acacia caven and in the myrtaceae such as Callistemon rigidus.
The staminodes are the sterile stamens that normally appear in certain flowers. Their function is varied and may have to do with the production of nectar or with the attraction function usually fulfilled by the petals.
Gynoecium
In angiosperms the gynoecium, also called pistil, consists of one or more carpels or carpel leaves that form a cavity, the ovary, inside which the ovules or seminal primordia are protected from both desiccation and attack by phytophagous insects.
The gynoecium consists of three parts: the ovary, bulging lower part that forms a cavity or locule inside which are the ovules; the style which is a more or less elongated column that supports the third component of the pistil: the stigma. This is constituted by a specialized glandular tissue for the reception of the grains of polen. Sometimes the style may be absent, and in such cases the stigma is said to be sessile.
If the carpels are separate or free from each other, the gynoecium is called dialicarpelate or apocarpic (as occurs in the genera Sedum, Kalanchoe and Paeonia); if, on the other hand, the carpels are welded together it is called gamocarpellar or syncarpous, which is most common.
In the dialycarpous flower each carpel constitutes a pistil, while in the syncarpous flower there is only one pistil. For example, Kalanchoe, with four free carpels, has four pistils. In the gamocarpellar or syncarpous gynoecium the union of the carpels may involve only a portion of the ovary, leaving both styles and stigmas free (example, the genus Turnera); it may involve the ovaries and styles, leaving the stigmas free (as occurs in the compositae and in Hibiscus), so that the number of carpels that make up the pistil can be determined by observation of the number of stigmas. Finally, in many occasions the union or welding of the carpels is total. In these cases the number of carpels can be determined through the number of stigmatic lobes (for example, in bignoniaceae).
The style is variable in length, from less than 0.5 mm (subsessile stigma) to more than 30 cm in certain varieties of maize, which is known as corn silk. It is usually borne at the apex of the ovary, but may be lateral or apparently borne at the base (gynobasic style). From the anatomical point of view, the style can be solid or hollow. In plants with hollow style the transmission tissue (through which the pollen tube grow to effect fertilization) consists of a layer of fairly differentiated epidermal cells surrounding a hollow canal (also known as stylar canal). The pollen tubes grow from the stigma into the ovary along the surface of that canal, usually through a thin layer of mucilage. In plants with solid styles, on the other hand, the epidermal cells are intimately fused and leave no space between them. The pollen tubes, in this case, grow between the cells of the transmission tissue (as in the case of Petunia,) or through cell walls (as in Gossypium,). The transmission tissue in solid styles includes an intercellular substance containing pectin, comparable to the mucilage found in the stylar canal of hollow styles.
From the point of view of the distribution of both types of styles among the different families of angiosperms, solid styles are considered typical of the eudicotyledons and are rare in the monocotyledons.
The stigma is variable in shape, feathery in the case of grasses, head-shaped in Citrus, lobed in Cucurbita, petaloid in Canna and even inverted umbrella-shaped in the case of Sarracenia. It has structural peculiarities that allow the germination of pollen and the development of the pollen tube that will reach the ovules. The stigma has been found to be covered by hydrophilic proteins on the outer wall; these are probably the ones that act in the recognition of suitable pollen and in the reactions of self-incompatibility, in which case sometimes callose is deposited to stop the germination of incompatible pollen.
Stigmas are divided into two major groups: wet and dry stigmas. Moist stigmas release an exudate during the receptive period and occur in families such as orchidaceae, scrophulariaceae and solanaceae. Wet stigmas may have papillae (papillose stigmas, as in Annona, Mandevilla, Bignonia and Punica) or no papillae (non-papillose stigmas, in Citrus, Impatiens, Opuntia and Tamarix). Dried stigmas do not release liquid secretions, but produce proteins or waxes. They can be feathery (grasses) or non-feathery and, in this case, papillose (Cordyline, Yucca Pelargonium or non-papillose (Asclepias, Capparis, Cyperus]).
The ovary is the lower part of the gynoecium that contains the ovules to be fertilized. It is formed by one or more modified leaves called carpels. Inside the ovary there are one or more cavities or locules that contain the eggs waiting to be fertilized. The eggs are inserted into the ovary in an area called the placenta.
One of the terminologies for describing the ovary refers to the point of insertion above the receptacle (where the other floral parts (perianth and androcecium) join and attach to the surface of the ovary. If the ovary is located above the point of insertion, it will be subterranean; if it is below, it will be infertile.
The seminal rudiment, also called the ovule, is the plant organ that forms in the ovary and contains the embryo sac within which are the oosphere or female gamete, the synergid cells, the median cell with the two polar nuclei and the antipodal cells. Surrounding the embryo sac is the nucella, the integuments, the chalaza and a funiculus that connects the ovule to the placenta.
The oospore comes from a spore, called megaspore or macrospore, through a process called megagametogenesis, which basically consists of mitotic divisions. Its nucleus is generally haploid, that is, it has half the chromosomes of the plant that gave rise to it. The oosphere fuses with one of the generative nuclei of the pollen grain during double fertilization to give rise to the embryo. The other generative nucleus will fuse with the polar nuclei of the middle cell and give rise to the endosperm.
The arrangement of the ovule in the cavity of the ovary is called placentation. The number of placentas is, in general, equal to the number of carpels forming the ovary. In certain cases, however, some of the placentas may atrophy and a pluricarpel ovary may contain only one ovule, as for example in grasses (Poaceae) and compositae (Asteraceae).
There are different types of placentation:
Marginal placentation: it is typical of unicarpel gynoecium (Leguminosae) or dialicarpel gynoecium (Magnoliaceae, Magnoliaceae, Ranunculaceae). Each carpel has a single placenta corresponding to the weld zone of the carpel leaf.
Parietal placentation: occurs in the gynoecium formed by two or more carpels welded by their edges forming a single cavity in the ovary, so that each placenta corresponds to the edges of two contiguous carpel leaves. Some of the families that present this type of placentation are: Orchids, Violaceae, Passifloraceae and Cucurbitaceae. In certain genera false septa form on the ovary wall increasing the placental surface: this is the so-called "laminar placentation", typical of the genus Papaver. In the Cruciferae (Brassicaceae) the ovary consists of two carpels joined at the edges that would delimit a single cavity. However, between the two sutures a membranous septum called replum develops, which separates the cavity into two locules. The ovules are arranged on both sides, in two series for each carpel. A variant of this type of placentation, difficult to interpret by mere examination of the ovary, is that of the Gramineae (Poaceae). In these species the ovary is bicarpelate, unilocular and uniseminated. The position of the ovule is lateral, as can be deduced from the position of the thread, and the placentation is therefore parietal.
Axillary placentation. Occurs in the gynoecium formed by two or more welded carpels in which each one carries the placenta in the central angle, so that the placental sutures form a column inside the ovary. The ovules of each locule are thus isolated from their neighbors by the carpellar septa. This type of placentation is found in Solanum, Citrus, liliaceae, iridaceae, among many other examples.
Central placentation. The unilocular gynoecium is formed by two or more united carpels and the ovules are fixed on a central column and without partitions with the ovary wall. This column may be a basal prolongation of the placenta, as in the Primulaceae, or it is the set of united placentas that persist after the dissolution of the septa, as in the Caryophyllaceae.
Basal placentation. This type of placentation occurs in species with pluricarpel and unilocular gynoecium. The ovule is arranged in the basal center of the ovary cavity. It is typical of the polygonaceae, chenopodiaceae and compositae families.
Sexuality
Floral sexuality is related to the presence or absence of the reproductive whorls: androecium and gynoecium. Flowers that have both whorls (i.e., will produce both male and female gametes) are said to be perfect, bisexual, monoclinous or, more frequently, hermaphrodites, as is the case with potato flowers (Solanum tuberosum, Solanaceae). In many other species, on the other hand, the flowers have only one reproductive whorl and are said to be diclinate, imperfect or unisexual, as is the case in mulberry (Morus nigra, moraceae) and pumpkin (Cucurbita maxima, cucurbitaceae). In the case that such a whorl is the androecium, the flowers are called male or staminate; while if the whorl present is the gynoecium, the flowers are called pistillate or female. There are some cases in which the flower does not present any of the reproductive whorls and only shows sepals and petals. The function of these flowers is to specialize, within a group of flowers that are perfect, in attracting pollinating insects to the inflorescence. Such flowers, called neutral or asexual, are usually arranged on the periphery of the inflorescence and can be observed, for example, in many species of the compositae family, such as the daisy (Bellis perennis) or sunflower (Helianthus annuus).
Floral formula and diagram
The floral diagram is a graphic representation of the arrangement of the floral parts and the arrangement of the different whorls, in a cross section of the flower. Each whorl is represented, by convention, with a concentric circumference around the gynoecium, indicated by a cut at the level of the ovary. The sepals are drawn as white lunules, the petals as black or sometimes colored lunules. The stamens are symbolized by cross sections of the anther, and the gynoecium is represented in the center of the diagram by a cross section of the ovary. Usually the pieces of one whorl alternate with the pieces of the previous whorl. The stamens may be opposite or alternate with respect to the petals. The welding between the pieces of each whorl or of opposite whorls is indicated by dotted lines.
By means of these diagrams the floral structure is well manifested, its symmetry is deduced from it, the number of members of each whorl, and in the case of the sepals and petals, their vernation, their welding or independence; of the androecium the relative position of the stamens with respect to the perianth, the concrescence or separation of the same, their union or autonomy with respect to the corolla and the introrse or extrorse position of the anthers. From the gynoecium, the number of carpels and cavities in the ovary and the placentation of the ovules can be observed.
The diagram above shows the floral diagram of Lilium, typical of the liliaceae family. The diagram shows that the flowers are hermaphrodites (have stamens and pistil), actinomorphics (have several planes of symmetry). The perigonium is formed by 6 tepals arranged in two trimerous whorls (that is, each of them is formed by three pieces), they are separated from each other and free from the other floral pieces (it is said, then, dialithepal). The androecium has 6 stamens arranged in 2 whorls also trimeres, the filaments are separated from each other and free from the other floral parts. The androcecium is diplostomatous (i.e. the outer whorl of stamens is opposite the outer tepals and the inner cycle is opposite the inner tepals). The gynoecium has superior ovary and is formed by 3 connate carpels, it is trilocular. The ovule has axillary placentation.
The floral formula is a way of symbolically representing the structure of a flower through the use of letters, numbers and other signs. Typically, the floral formula is used to represent the morphological characteristics of the flowers of a given plant family, rather than of a particular species. The following are the most commonly used symbols:
K = calyx; for example, "K5" indicates that the flower has 5 sepals.
C = corolla; for example, "C3" means that the flower has 3 petals.
Z = is added if the corolla is zygomorphic; e.g., "CZ6" = indicates a zygomorphic corolla with 6 petals.
A = androecium; e.g., "A∞" means having many stamens.
G = gynoecium; thus, "G(3)1∞" indicates a gynoecium with a succumbent ovary (hence the "G" is underlined), composed of 3 capelli joined (hence the number three is put in parentheses), with a single locule and numerous ovules per locule. The number of locules of the ovary is given as a subscript of the number of carpels; the number of ovules per locule is given as an exponent.
A floral formula then acquires a form like the following, typical of the lily family:K3 C3 A6 G(3)3∞which indicates that the flowers of this family have 3 sepals, 3 petals, an androcecium with 6 stamens and a gynoecium with a succulent ovary formed by 3 carpels joined, with three loculi and numerous ovules per locule.
The floral formula that symbolically describes the floral structure of ''Oxalis'', previously described, is:K5 C5 A10 G(5)5∞
Double-flowered
The term double-flower describes those flowers that present an extra number of petals, much higher than the usual number for the species in question, because in them a group or all the stamens are replaced by petals.
The "double-flowered" characteristic is denoted in the scientific names of the varieties by the abbreviation fl. pl. (flore pleno, meaning "full flowering"). It has been the first abnormality to be documented in flowers and one of the most popular characters in many ornamental species, such as rose bush, camellia and carnation.
Floral morphology in some families of plants
Amaryllidaceae
Within the monocotyledons, plants belonging to the Amaryllidaceae family have the simplest and most typical flowers. The flowers are hermaphrodites, actinomorphics (i.e., of radial symmetry) or slightly zygomorphics, pedicellate or sessiles, showy, each associated with a filiform bract. The perigonium is composed of six tepals arranged in two whorls of 3 pieces each, which have approximately the same shape and size. The tepals are free from each other or may be welded at the base forming a perigonial tube or hypanthium, which is extended in some cases in a "crown"—also called paraperigonium or false corolla, for example in Narcissus—sometimes reduced to scales or unremarkable teeth.
The androecium has six stamens arranged in two whorls of three pieces each—rarely only three stamens, as in Zephyra, or from 9 to 18, as in Gethyllis—opposite the tepals, inserted on the perigonium tube or the base of the tepals. The filaments are slender, filiform or flared at the base, may be free (Hippeastrum) or bound together by a membrane surrounding the entire ovary called the "staminal cup", as for example in Hymenocallis. The anthers are oblong or linear. The stamens sometimes have appendages that form a staminal corona—for example in Hymenocallis.
The gynoecium has an ovary in the case of amaryllioids and a superior ovary in agapanthoids and allioids. It is formed by three carpels joined and delimiting three cavities or loculi, which contain from two to three to many anthropoid ovules of axillary placentation. The ovary is continuous with a style and with a minute, capitate to deeply trifid stigma. They usually present floral nectarys and the secretion of nectar comes from the perigonium or gynoecium, usually in the septa of the ovary.
The flowers are arranged in cymose inflorescences at the apex of a scape, sometimes compressed and umbel-like, and are thus called "pseudoumbels". They are rarely reduced to solitary flowers. The involucral bracts, which enclose the flower buds, may be present or absent.
Compositae
In compositae, the sunflower family and margarita, the flowers are small, hermaphrodites or, sometimes, functionally unisexuals or sterile (in the latter case they are called neutral). By their symmetry they can be both actinomorphic and zygomorphic, i.e. they can have radial or bilateral symmetry, respectively. Because of the number of pieces that compose each cycle, the flowers of the composites are pentamerous. The calyx is null or the sepals are deeply modified, forming a pappus, from two to many scales, bristles or hairs, persistent, sometimes joined.
The corolla is gametopetalous, the five petals may be joined forming a tube with 4 or 5 lobes (in the flower called tubulose flower or floret, or two groups of petals joined (in the case of bilabiated flowers, with an upper lip formed by 2 petals and a lower lip formed by 3 petals), or they can present a short tube and the limb prolonged laterally in a ligule with 3 or 5 teeth (ligulated flowers).
The androecium usually has 5 stamens, which alternate with the corolla lobes. The filaments, separated from each other, are inserted in the corolla tube. The anthers are joined forming a tube around the style in which the pollen is released, and the style then grows through this tube, pushing out or taking up the pollen (with variably developed hairs) and presenting it to floral visitors, after which the stigmas become receptive (i.e., with a plunger or brush pollination mechanism).
The gynoecium is two carpels joined, with the ovary being inferoid and unilocular. The pistil has a style that usually has a nectary at its apex. The style is distally divided into two branches (stylar branches) which have style papillae on their adaxial side arranged in two separate lines or in a single continuous band.
Legumes
Leguminosae, the acacias and bean family, have a great diversity of flower types, depending on the subfamily considered, mimosoideae, caesalpinioideae and faboideae. The flowers can range from small to large, actinomorphics (in Mimosoideae) to slightly or deeply zygomorphics (Papilionoideae and most of Caesalpinioideae). Irregularities in floral symmetry in these cases involve the perianth and androcecium. The perianth almost always has a distinct calyx and corolla. However, the corolla may be absent, in which case the perianth is said to be sepaline, as occurs in dozens of cesalpinioid genera. The calyx has 5 sepals (rarely 3 or 6) arranged in a single cycle, which may be wholly or partially united with each other. The calyx, moreover, may or may not be persistent, is rarely acrescent (i.e. continuing in the fruit), imbricate or valvate. The corolla is composed of 5 free petals (commonly less than 5 or absent in Swartzieae, Amorphieae and Caesalpinioideae, or 3 to 4 in Mimosoideae) or partially united and presents, in general, a characteristic morphology. Thus, the papilionaceous or amaripose corolla is composed of a highly developed upper petal, known as vexillum, two lateral petals or wings and two lower pieces often connivent that constitute a symmetrical structure called carina or keel. This architecture is very similar to that of cesalpinoid flowers but, unlike the latter, with vernation vexillary or descending, i.e., with the vexillum covering the rest of the corolla pieces inside the flower bud.
The gynoecium has superior ovary, monocarpellar, with very variable development and tendency to reduce the number of ovules.
Gramineae
Gramineae, the grass and cereal family, have deeply modified flowers. The elementary inflorescence in this family is a small spike formed by one or more seated or sessile flowers on a jointed rachis, often very short, called rachilla and protected by sterile bracts called glumes. This type of inflorescence is called spikelet. The flowers can be hermaphrodites or unisexuals and present a rudimentary perianth of 2 or 3 pieces, the lodiculae or glumellulae. These lodicules are the organs that, when they become turgid, determine the opening of the antecio or floral box during flowering, allowing the feathery stigmas and the stamens to be exposed. The anthers are formed by the lemma, attached to the rachilla, and the palea inserted on the floral axis that arises above the rachilla in the axil of the lemma and supports the floral organs themselves. The lemma (or lower glumella) is keel-shaped, can be mutic or aristate, and embraces the palea with its edges. The arista arises at the extremity of the lemma or on its dorsum. The upper palea or glumella is lanceolate, binervate and is like a cap that encloses the flower. The glumes are inserted above the rachilla, one lower than the other.
Orchids
No plant family has such a diverse range of flowers. Flowers are highly specialized in relation to their pollinators. Flowers are hermaphrodite (rarely unisexual), generally zygomorphic (bilaterally symmetrical), usually resupinates (i.e., the floral parts rotate 180° during development), often conspicuous and epigynous (i.e., the perianth parts are arranged above the ovary).
In the vast majority of genera, the flowers consist of three external parts called sepals, two lateral and one dorsal, and three internal elements called petals, the lower one modified into a lip or labellum of larger size and more intense color than the others. Some authors interpret the perianth of orchids as a perigonium, formed by six tepals arranged in two whorls. The different parts of the perianth may be separated from each other or fused at the base. The sepals, or outer tepals, are usually petaloid (petal-like), imbricate. Sometimes the two lateral sepals are fused into a single element called a synsepal. The petals, or inner tepals, are always separate, sometimes with dots, spots and various colors. The labellum is the middle petal, is larger in size than the two lateral petals, and its shape is extremely variable: it often has three lobes, or unusual shapes, and with fleshy bumps or ridges or a basal spur, and often with a different coloration pattern than the lateral petals.
The androecium is usually formed by one or two stamens (sometimes three), if only one derived from the middle stamen of the ancestral outer whorl and usually with two vestigial staminodes derived from the lateral stamens of an ancestral inner whorl. In some subfamilies, as in Apostasioideae or Cypripedioideae, there are two or three fertile stamens. When there are two, they have derived from the two lateral stamens of the ancestral inner whorl, and when three, they have originated from the two laterals of the inner whorl and the middle stamen of the outer whorl. The androcecium is fused to the style and stigma, which are highly modified, forming a structure known as a column, gynostema or gynostegium. The theca of the anthers are arranged in the portion of the gynostema called the clinandrium or androcline. The pollen is granular, in tetrads or agglutinated in two to eight soft or hard masses called pollinias. These pollinia present a filiform appendage—called caudicula—which is united with a sticky mass—retinaculum or viscidium—on the rostellum, a structure derived from the stigma with the shape of an elongated lobe and which is located on the receptive portion of the stigma. The set of pollinia, caudiculae and retinaculae is called pollinarium, which is the transport unit of the pollen during pollination. The anthers are longitudinally dehiscent and their connective is often modified into an operculum that covers the anther until pollination.
The gynoecium consists of three carpels fused together, with the inferior ovary, which may have one locule or three, and numerous ovules (up to millions) of placentation usually parietal, but occasionally axillary placentation.
Orchids are, in general, producers of nectar, a substance that they use as a reward for pollinators. The nectarys are variable in position and type. For example, they are found on the spur of the labellum, or on the apices of the sepals, or on the inner walls of the gynoecium. Species that do not produce nectar are autogamous or apomictics, i.e., they do not need pollinators to produce seeds.
See also
Flower
Pollination
ABC model of flower development
Notes
References
Botany
Morphology (biology)
Flowers
Plant morphology
Plant reproductive system
Plant sexuality
Pollination | Floral morphology | [
"Biology"
] | 10,164 | [
"Behavior",
"Plants",
"Plant sexuality",
"Morphology (biology)",
"Plant morphology",
"Botany",
"Sexuality"
] |
71,883,718 | https://en.wikipedia.org/wiki/Barbara%20Thenn | Barbara Thenn (1519-1579) was an Austrian merchant and Münzmeister.
She was a member of the rich merchant family Alt of Salzburg, and the aunt of Salome Alt. She married Marx Thenn, Münzmeister of the Arch Bishopric of Salzburg. When her spouse died in 1552, she successfully applied to succeed him in his public office as Münzmeister. It was almost unique for a woman to have such an office. She managed the state coin workshop of Salzburg between 1552 and 1572. In addition, she also managed the iron works in Hammerau, and the silver and copper mines in Kitzbühel.
There is a memorial to Barbara Thenn in Salzburg.
References
1519 births
1579 deaths
16th-century Austrian people
Austrian merchants
16th-century merchants
16th-century businesswomen
Miners
Ironmasters
Coins of Austria
16th-century Austrian women
Merchants from the Holy Roman Empire | Barbara Thenn | [
"Chemistry"
] | 186 | [
"Metallurgists",
"Ironmasters"
] |
71,884,733 | https://en.wikipedia.org/wiki/Acuitas%20Therapeutics | Acuitas Therapeutics Inc. is a Canadian biotechnology company based in Vancouver, British Columbia. The company was established in February 2009 to specialize in the development of delivery systems for nucleic acid therapeutics based on lipid nanoparticle (LNP) technology, a key component of the mRNA vaccines deployed for COVID-19.
History
Inex Pharmaceuticals
Pieter Cullis was among several scientists experimenting with liposomes in the early 1980s, fascinated by their properties in many aspects of human biology. Cullis discovered he could load cancer drugs into liposomes, inspiring him and several colleagues at the University of British Columbia to form Inex Pharmaceuticals in 1992. One of Inex's co-founders was Thomas Madden, who had recently emigrated to Canada from the United Kingdom to complete post-doctoral studies in biochemistry.
Tekmira Pharmaceuticals
To improve the prospects of successfully advancing gene therapy techniques, Cullis developed and patented a new form of lipid nanoparticle designed to deliver genetic material to recipient cells. From 1994 onward, a series of patents were filed describing the technology Cullis and his colleagues created, including the addition of a chemical called polyethylene glycol (PEG) to further increase the LNP's ability to pass into cells.
Several spinoff companies emerged based on the research and intellectual property, including Protiva Biotherapeutics (which focused on gene therapies based on RNAi). In 2001, Inex was developing topotecan with GlaxoSmithKline and by 2004 was in the research stage of preparing their own targeted cancer vaccine program. However, Cullis left the company after the Food and Drug Administration declined to approve their chemotherapy products. Inex then downsized and rebranded to Tekmira Pharmaceuticals. This led to $28.5 million in funding from “large biotechnology companies” for further development of anti-cancer drugs and RNA therapeutics for other diseases.
AlCana and Acuitas
Madden, Cullis and Michael Hope then founded AlCana Technologies in February 2009, later changing its name to Acuitas Therapeutics. With early financial support from the National Research Council Canada's Industrial Research Assistance Program (NRC IRAP), the company spent several years establishing its research and development capabilities and building out its staff. This led to its development of a viable lipid nanoparticle platform that showed promise for use in a variety of medical applications including chemotherapy, gene therapy and genetic vaccines. By 2012, the company had decided to focus on LNP development for the delivery of mRNA.
The Natural Research Council Canada awarded Acuitas a $173,020 grant in September 2013 and a $498,640 grant in February 2015 to continue their research and development.
In April 2016, Acuitas entered into a development and option agreement with German biotechnology company CureVac to jointly develop a product incorporating Acuitas' LNP technology with CureVac's mRNA materials. The encapsulated mRNA product described under the agreement was commissioned for use in in vitro and animal testing for pre-clinical trials of a vaccine candidate. Acuitas also worked on developing an mRNA vaccine against rabies.
COVID-19
According to president and CEO Thomas Madden, Acuitas began working towards a COVID-19 vaccine in February 2020. The company also partnered with CureVac and Imperial College London for their own vaccine trials. Madden noted that the mRNA vaccine platform would allow for rapid development of updated vaccines in case the SARS-CoV-2 virus evolved beyond the immunity generated by the initial formulation, though additional clinical testing would still be required. He also stated that the Pfizer–BioNTech COVID-19 vaccine would stop the spread of the virus and infection in vaccinated individuals.
On December 9, 2020, Acuitas released a statement celebrating Health Canada's approval of Pfizer and BioNTech's BNT162b2 COVID-19 vaccine, stating they had “made history” due to their collaboration through the LNP delivery system, “a key element… in the development of this vaccine.” As a privately held company, Acuitas doesn't publicly publish its earnings. However, Madden stated the company's annual revenues were "more than tens of millions of dollars" as of the end of 2020, having increased by 75% in the prior several years leading up to the COVID-19 crisis and expectations to grow by "at least that amount" through to 2022.
Acuitas entered a long-term partnership with Science World in January 2022. In April 2022, Acuitas completed an agreement with Korean biotechnology company GC Biopharma to develop vaccines and therapeutics using their joint LNP-mRNA platform. In June 2022, Acuitas donated $25,000 to the Brain Tumour Foundation of Canada to create the Frazer Anderson Pediatric Research Grant. The company entered an agreement with genetic editing company Arbor Biotechnologies in August 2022 to target rare liver diseases, combining Acuitas' LNP technology with Arbor's CRISPR gene editing capabilities.
In June 2023, Bayer announced it had entered a partnership with Acuitas to use its lipid nanoparticles to deliver in vivo gene editing products to the liver.
Organization
Partners
Acuitas has partnered with several pharmaceutical companies and universities to collaboratively advance specific product candidates, as well as to support the broader development of the personalized medicine sector. It is a member of BIOTECanada, a biotechnology industry association, and a sponsor of Life Sciences British Columbia. It has participated in research published by the University of Pennsylvania, Mount Sinai Health System, Chulalongkorn University, Thomas Jefferson University, and BioNTech.
Acuitas is a sponsor of the Vancouver-based Student Biotechnology Network.
Ownership
Rumours circulated in early 2022 that Prime Minister Justin Trudeau owned a 40% stake in Acuitas, either directly or through the Trudeau Foundation. This was refuted by the Office of the Prime Minister, CEO Thomas Madden and co-founder Pieter Cullis.
References
External links
Biotechnology companies
Nanotechnology companies
Canadian companies established in 2009 | Acuitas Therapeutics | [
"Materials_science",
"Engineering",
"Biology"
] | 1,253 | [
"Nanotechnology",
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"Nanotechnology companies",
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71,886,336 | https://en.wikipedia.org/wiki/Nucleon%20magnetic%20moment | The nucleon magnetic moments are the intrinsic magnetic dipole moments of the proton and neutron, symbols μp and μn. The nucleus of an atom comprises protons and neutrons, both nucleons that behave as small magnets. Their magnetic strengths are measured by their magnetic moments. The nucleons interact with normal matter through either the nuclear force or their magnetic moments, with the charged proton also interacting by the Coulomb force.
The proton's magnetic moment was directly measured in 1933 by Otto Stern team in University of Hamburg. While the neutron was determined to have a magnetic moment by indirect methods in the mid-1930s, Luis Alvarez and Felix Bloch made the first accurate, direct measurement of the neutron's magnetic moment in 1940. The proton's magnetic moment is exploited to make measurements of molecules by proton nuclear magnetic resonance. The neutron's magnetic moment is exploited to probe the atomic structure of materials using scattering methods and to manipulate the properties of neutron beams in particle accelerators.
The existence of the neutron's magnetic moment and the large value for the proton magnetic moment indicate that nucleons are not elementary particles. For an elementary particle to have an intrinsic magnetic moment, it must have both spin and electric charge. The nucleons have spin ħ/2, but the neutron has no net charge. Their magnetic moments were puzzling and defied a valid explanation until the quark model for hadron particles was developed in the 1960s. The nucleons are composed of three quarks, and the magnetic moments of these elementary particles combine to give the nucleons their magnetic moments.
Description
The CODATA recommended value for the magnetic moment of the proton is μp = = The best available measurement for the value of the magnetic moment of the neutron is Here, μN is the nuclear magneton, a standard unit for the magnetic moments of nuclear components, and μB is the Bohr magneton, both being physical constants. In SI units, these values are and A magnetic moment is a vector quantity, and the direction of the nucleon's magnetic moment is determined by its spin. The torque on the neutron that results from an external magnetic field is towards aligning the neutron's spin vector opposite to the magnetic field vector.
The nuclear magneton is the spin magnetic moment of a Dirac particle, a charged, spin-1/2 elementary particle, with a proton's mass p, in which anomalous corrections are ignored. The nuclear magneton is
where is the elementary charge, and is the reduced Planck constant. The magnetic moment of such a particle is parallel to its spin. Since the neutron has no charge, it should have no magnetic moment by the analogous expression. The non-zero magnetic moment of the neutron thus indicates that it is not an elementary particle. The sign of the neutron's magnetic moment is that of a negatively charged particle. Similarly, that the magnetic moment of the proton, is not almost equal to 1 N indicates that it too is not an elementary particle. Protons and neutrons are composed of quarks, and the magnetic moments of the quarks can be used to compute the magnetic moments of the nucleons.
Although the nucleons interact with normal matter through magnetic forces, the magnetic interactions are many orders of magnitude weaker than the nuclear interactions. The influence of the neutron's magnetic moment is therefore only apparent for low energy, or slow, neutrons. Because the value for the magnetic moment is inversely proportional to particle mass, the nuclear magneton is about 1/2000 as large as the Bohr magneton. The magnetic moment of the electron is therefore about 1000 times larger than that of the nucleons.
The magnetic moments of the antiproton and antineutron have the same magnitudes as their antiparticles,
the proton and neutron, but they have opposite sign.
Measurement
Proton
The magnetic moment of the proton was discovered in 1933 by Otto Stern, Otto Robert Frisch and Immanuel Estermann at the University of Hamburg. The proton's magnetic moment was determined by measuring the deflection of a beam of molecular hydrogen by a magnetic field. Stern won the Nobel Prize in Physics in 1943 for this discovery.
Neutron
The neutron was discovered in 1932, and since it had no charge, it was assumed to have no magnetic moment. Indirect evidence suggested that the neutron had a non-zero value for its magnetic moment, however, until direct measurements of the neutron's magnetic moment in 1940 resolved the issue.
Values for the magnetic moment of the neutron were independently determined by R. Bacher at the University of Michigan at Ann Arbor (1933) and I. Y. Tamm and S. A. Altshuler in the Soviet Union (1934) from studies of the hyperfine structure of atomic spectra. Although Tamm and Altshuler's estimate had the correct sign and order of magnitude (), the result was met with skepticism.
By 1934 groups led by Stern, now at the Carnegie Institute of Technology in Pittsburgh, and I. I. Rabi at Columbia University in New York had independently measured the magnetic moments of the proton and deuteron. The measured values for these particles were only in rough agreement between the groups, but the Rabi group confirmed the earlier Stern measurements that the magnetic moment for the proton was unexpectedly large. Since a deuteron is composed of a proton and a neutron with aligned spins, the neutron's magnetic moment could be inferred by subtracting the deuteron and proton magnetic moments. The resulting value was not zero and had a sign opposite to that of the proton. By the late 1930s, accurate values for the magnetic moment of the neutron had been deduced by the Rabi group using measurements employing newly developed nuclear magnetic resonance techniques.
The value for the neutron's magnetic moment was first directly measured by L. Alvarez and F. Bloch at the University of California at Berkeley in 1940. Using an extension of the magnetic resonance methods developed by Rabi, Alvarez and Bloch determined the magnetic moment of the neutron to be . By directly measuring the magnetic moment of free neutrons, or individual neutrons free of the nucleus, Alvarez and Bloch resolved all doubts and ambiguities about this anomalous property of neutrons.
Unexpected consequences
The large value for the proton's magnetic moment and the inferred negative value for the neutron's magnetic moment were unexpected and could not be explained. The unexpected values for the magnetic moments of the nucleons would remain a puzzle until the quark model was developed in the 1960s.
The refinement and evolution of the Rabi measurements led to the discovery in 1939 that the deuteron also possessed an electric quadrupole moment. This electrical property of the deuteron had been interfering with the measurements by the Rabi group. The discovery meant that the physical shape of the deuteron was not symmetric, which provided valuable insight into the nature of the nuclear force binding nucleons. Rabi was awarded the Nobel Prize in 1944 for his resonance method for recording the magnetic properties of atomic nuclei.
Nucleon gyromagnetic ratios
The magnetic moment of a nucleon is sometimes expressed in terms of its -factor, a dimensionless scalar. The convention defining the -factor for composite particles, such as the neutron or proton, is
where is the intrinsic magnetic moment, is the spin angular momentum, and is the effective -factor. While the -factor is dimensionless, for composite particles it is defined relative to the nuclear magneton. For the neutron, is , so the neutron's -factor is while the proton's g-factor is
The gyromagnetic ratio, symbol , of a particle or system is the ratio of its magnetic moment to its spin angular momentum, or
For nucleons, the ratio is conventionally written in terms of the proton mass and charge, by the formula
The neutron's gyromagnetic ratio is The proton's gyromagnetic ratio is The gyromagnetic ratio is also the ratio between the observed angular frequency of Larmor precession and the strength of the magnetic field in nuclear magnetic resonance applications, such as in MRI imaging. For this reason, the quantity γ/2π called "gamma bar", expressed in the unit MHz/T, is often given. The quantities and are therefore convenient.
Physical significance
Larmor precession
When a nucleon is put into a magnetic field produced by an external source, it is subject to a torque tending to orient its magnetic moment parallel to the field (in the case of the neutron, its spin is antiparallel to the field). As with any magnet, this torque is proportional the product of the magnetic moment and the external magnetic field strength. Since the nucleons have spin angular momentum, this torque will cause them to precess with a well-defined frequency, called the Larmor frequency. It is this phenomenon that enables the measurement of nuclear properties through nuclear magnetic resonance. The Larmor frequency can be determined from the product of the gyromagnetic ratio with the magnetic field strength. Since for the neutron the sign of γn is negative, the neutron's spin angular momentum precesses counterclockwise about the direction of the external magnetic field.
Proton nuclear magnetic resonance
Nuclear magnetic resonance employing the magnetic moments of protons is used for nuclear magnetic resonance (NMR) spectroscopy. Since hydrogen-1 nuclei are within the molecules of many substances, NMR can determine the structure of those molecules.
Determination of neutron spin
The interaction of the neutron's magnetic moment with an external magnetic field was exploited to determine the spin of the neutron. In 1949, D. Hughes and M. Burgy measured neutrons reflected from a ferromagnetic mirror and found that the angular distribution of the reflections was consistent with spin . In 1954, J. Sherwood, T. Stephenson, and S. Bernstein employed neutrons in a Stern–Gerlach experiment that used a magnetic field to separate the neutron spin states. They recorded the two such spin states, consistent with a spin particle. Until these measurements, the possibility that the neutron was a spin particle could not have been ruled out.
Neutrons used to probe material properties
Since neutrons are neutral particles, they do not have to overcome Coulomb repulsion as they approach charged targets, unlike protons and alpha particles. Neutrons can deeply penetrate matter. The magnetic moment of the neutron has therefore been exploited to probe the properties of matter using scattering or diffraction techniques. These methods provide information that is complementary to X-ray spectroscopy. In particular, the magnetic moment of the neutron is used to determine magnetic properties of materials at length scales of 1–100 Å using cold or thermal neutrons. B. Brockhouse and C. Shull won the Nobel Prize in physics in 1994 for developing these scattering techniques.
Control of neutron beams by magnetism
As neutrons carry no electric charge, neutron beams cannot be controlled by the conventional electromagnetic methods employed in particle accelerators. The magnetic moment of the neutron allows some control of neutrons using magnetic fields, however, including the formation of polarized neutron beams. One technique employs the fact that cold neutrons will reflect from some magnetic materials at great efficiency when scattered at small grazing angles. The reflection preferentially selects particular spin states, thus polarizing the neutrons. Neutron magnetic mirrors and guides use this total internal reflection phenomenon to control beams of slow neutrons.
Nuclear magnetic moments
Since an atomic nucleus consists of a bound state of protons and neutrons, the magnetic moments of the nucleons contribute to the nuclear magnetic moment, or the magnetic moment for the nucleus as a whole. The nuclear magnetic moment also includes contributions from the orbital motion of the charged protons. The deuteron, consisting of a proton and a neutron, has the simplest example of a nuclear magnetic moment. The sum of the proton and neutron magnetic moments gives 0.879 μN, which is within 3% of the measured value 0.857 μN. In this calculation, the spins of the nucleons are aligned, but their magnetic moments offset because of the neutron's negative magnetic moment.
Nature of the nucleon magnetic moments
A magnetic dipole moment can be generated by two possible mechanisms. One way is by a small loop of electric current, called an "Ampèrian" magnetic dipole. Another way is by a pair of magnetic monopoles of opposite magnetic charge, bound together in some way, called a "Gilbertian" magnetic dipole. Elementary magnetic monopoles remain hypothetical and unobserved, however. Throughout the 1930s and 1940s it was not readily apparent which of these two mechanisms caused the nucleon intrinsic magnetic moments. In 1930, Enrico Fermi showed that the magnetic moments of nuclei (including the proton) are Ampèrian. The two kinds of magnetic moments experience different forces in a magnetic field. Based on Fermi's arguments, the intrinsic magnetic moments of elementary particles, including the nucleons, have been shown to be Ampèrian. The arguments are based on basic electromagnetism, elementary quantum mechanics, and the hyperfine structure of atomic s-state energy levels. In the case of the neutron, the theoretical possibilities were resolved by laboratory measurements of the scattering of slow neutrons from ferromagnetic materials in 1951.
Anomalous magnetic moments and meson physics
The anomalous values for the magnetic moments of the nucleons presented a theoretical quandary for the 30 years from the time of their discovery in the early 1930s to the development of the quark model in the 1960s. Considerable theoretical efforts were expended in trying to understand the origins of these magnetic moments, but the failures of these theories were glaring. Much of the theoretical focus was on developing a nuclear-force equivalence to the remarkably successful theory explaining the small anomalous magnetic moment of the electron.
The problem of the origins of the magnetic moments of nucleons was recognized as early as 1935. G. C. Wick suggested that the magnetic moments could be caused by the quantum-mechanical fluctuations of these particles in accordance with Fermi's 1934 theory of beta decay. By this theory, a neutron is partly, regularly and briefly, disassociated into a proton, an electron, and a neutrino as a natural consequence of beta decay. By this idea, the magnetic moment of the neutron was caused by the fleeting existence of the large magnetic moment of the electron in the course of these quantum-mechanical fluctuations, the value of the magnetic moment determined by the length of time the virtual electron was in existence. The theory proved to be untenable, however, when H. Bethe and R. Bacher showed that it predicted values for the magnetic moment that were either much too small or much too large, depending on speculative assumptions.
Similar considerations for the electron proved to be much more successful. In quantum electrodynamics (QED), the anomalous magnetic moment of a particle stems from the small contributions of quantum mechanical fluctuations to the magnetic moment of that particle. The g-factor for a "Dirac" magnetic moment is predicted to be for a negatively charged, spin-1/2 particle. For particles such as the electron, this "classical" result differs from the observed value by around 0.1%; the difference compared to the classical value is the anomalous magnetic moment. The g-factor for the electron is measured to be QED is the theory of the mediation of the electromagnetic force by photons. The physical picture is that the effective magnetic moment of the electron results from the contributions of the "bare" electron, which is the Dirac particle, and the cloud of "virtual", short-lived electron–positron pairs and photons that surround this particle as a consequence of QED. The effects of these quantum mechanical fluctuations can be computed theoretically using Feynman diagrams with loops.
The one-loop contribution to the anomalous magnetic moment of the electron, corresponding to the first-order and largest correction in QED, is found by calculating the vertex function shown in the diagram on the right. The calculation was discovered by J. Schwinger in 1948. Computed to fourth order, the QED prediction for the electron's anomalous magnetic moment agrees with the experimentally measured value to more than 10 significant figures, making the magnetic moment of the electron one of the most accurately verified predictions in the history of physics.
Compared to the electron, the anomalous magnetic moments of the nucleons are enormous. The g-factor for the proton is 5.6, and the chargeless neutron, which should have no magnetic moment at all, has a g-factor of −3.8. Note, however, that the anomalous magnetic moments of the nucleons, that is, their magnetic moments with the expected Dirac particle magnetic moments subtracted, are roughly equal but of opposite sign: , but .
The Yukawa interaction for nucleons was discovered in the mid-1930s, and this nuclear force is mediated by pion mesons. In parallel with the theory for the electron, the hypothesis was that higher-order loops involving nucleons and pions may generate the anomalous magnetic moments of the nucleons. The physical picture was that the effective magnetic moment of the neutron arose from the combined contributions of the "bare" neutron, which is zero, and the cloud of "virtual" pions and photons that surround this particle as a consequence of the nuclear and electromagnetic forces. The Feynman diagram at right is roughly the first-order diagram, with the role of the virtual particles played by pions. As noted by A. Pais, "between late 1948 and the middle of 1949 at least six papers appeared reporting on second-order calculations of nucleon moments". These theories were also, as noted by Pais, "a flop" they gave results that grossly disagreed with observation. Nevertheless, serious efforts continued along these lines for the next couple of decades, to little success. These theoretical approaches were incorrect because the nucleons are composite particles with their magnetic moments arising from their elementary components, quarks.
Quark model of nucleon magnetic moments
In the quark model for hadrons, the neutron is composed of one up quark (charge ) and two down quarks (charge ) while the proton is composed of one down quark (charge ) and two up quarks (charge ).
The magnetic moment of the nucleons can be modeled as a sum of the magnetic moments of the constituent quarks, although this simple model belies the complexities of the Standard Model of Particle Physics.
The calculation assumes that the quarks behave like pointlike Dirac particles, each having their own magnetic moment, as computed using an expression similar to the one above for the nuclear magneton:
where the q-subscripted variables refer to quark magnetic moment, charge, or mass. Simplistically, the magnetic moment of a nucleon can be viewed as resulting from the vector sum of the three quark magnetic moments, plus the orbital magnetic moments caused by the movement of the three charged quarks within it.
In one of the early successes of the Standard Model (SU(6) theory), in 1964 M. Beg, B. Lee, and A. Pais theoretically calculated the ratio of proton-to-neutron magnetic moments to be , which agrees with the experimental value to within 3%.
The measured value for this ratio is . A contradiction of the quantum mechanical basis of this calculation with the Pauli exclusion principle led to the discovery of the color charge for quarks by O. Greenberg in 1964.
From the nonrelativistic quantum-mechanical wave function for baryons composed of three quarks, a straightforward calculation gives fairly accurate estimates for the magnetic moments of neutrons, protons, and other baryons. For a neutron, the magnetic moment is given by where d and u are the magnetic moments for the down and up quarks respectively. This result combines the intrinsic magnetic moments of the quarks with their orbital magnetic moments and assumes that the three quarks are in a particular, dominant quantum state.
The results of this calculation are encouraging, but the masses of the up or down quarks were assumed to be the mass of a nucleon. The masses of the quarks are actually only about 1% that of a nucleon. The discrepancy stems from the complexity of the Standard Model for nucleons, where most of their mass originates in the gluon fields, virtual particles, and their associated energy that are essential aspects of the strong force.
Furthermore, the complex system of quarks and gluons that constitute a nucleon requires a relativistic treatment.
Nucleon magnetic moments have been successfully computed from first principles, requiring significant computing resources.
See also
Aharonov–Casher effect
LARMOR neutron microscope
Neutron electric dipole moment
Neutron triple-axis spectrometry
References
Bibliography
S. W. Lovesey (1986). Theory of Neutron Scattering from Condensed Matter. Oxford University Press. .
Donald H. Perkins (1982). Introduction to High Energy Physics. Reading, Massachusetts: Addison Wesley, .
John S. Rigden (1987). Rabi, Scientist and Citizen. New York: Basic Books, Inc., .
Sergei Vonsovsky (1975). Magnetism of Elementary Particles. Moscow: Mir Publishers.
External links
Electric and magnetic fields in matter
Magnetic moment
Magnetism
Magnetostatics
magnetic moment
magnetic moment
Physical quantities | Nucleon magnetic moment | [
"Physics",
"Chemistry",
"Materials_science",
"Mathematics",
"Engineering"
] | 4,431 | [
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"Physical quantities",
"Quantity",
"Electric and magnetic fields in matter",
"Materials science",
"Magnetic moment",
"Condensed matter physics",
"Physical properties",
"Moment (physics)"
] |
71,886,846 | https://en.wikipedia.org/wiki/Rs16891982 | In genetics, rs16891982, also known as F374L, is the name for a single nucleotide polymorphism found in the SLC45A2 gene. The SNP consists of two alleles: C (cytosine) and G (guanine). It is associated with skin tone and hair/eye color. It is a type of missense mutation.
C allele homozygosity is associated with black hair in people of European descent, although those with this genotype are usually of non-European descent.
C/G allele heterozygosity is associated with black hair in people of European descent
G allele homozygosity is associated with light skin, hair, and eye color (European ancestry), those with this genotype also have a slightly higher susceptibility to melanoma.
References
SNPs on chromosome 5 | Rs16891982 | [
"Biology"
] | 187 | [
"SNPs on chromosome 5",
"Single-nucleotide polymorphisms"
] |
71,887,388 | https://en.wikipedia.org/wiki/ITU-T%20Study%20Group%2015 | The ITU-T Study Group 15 (SG15) 'Transport' is a standardization committee of ITU-T concerned with networks, technologies and infrastructures for transport, access and home. It responsible for standards such as GPON, G.fast, etc.
Administratively, SG15 is a statutory meeting of the World Telecommunication Standardization Assembly (WTSA), which creates the ITU-T Study Groups and appoints their management teams. The secretariat is provided by the Telecommunication Standardization Bureau (under Director Chaesub Lee).
The goal of SG15 is to produce recommendations (international standards) for networks.
Area of work
SG15 focuses on developing standards and recommendations related to optical transport networks, access network transport, and associated technologies.
Some of the key responsibilities of SG15 include:
Developing international standards for optical and transport networks, which covers fiber-optic communication systems, dense wavelength division multiplexing (DWDM), and synchronization aspects.
Addressing issues related to access network transport, such as digital subscriber lines (DSL), gigabit-capable passive optical networks (GPON), and Ethernet passive optical networks (EPON).
Developing recommendations for network management, control, and performance monitoring, as well as resilience, protection, and restoration mechanisms.
SG15 collaborates with other ITU-T study groups, regional standardization bodies, and industry stakeholders to ensure a comprehensive and coordinated approach to global telecommunication standardization.
See also
ITU-T
References
External links
ITU main site
ITU-T Study Group 15 web site
International Telecommunication Union
ITU-T Study Groups
Computer networking | ITU-T Study Group 15 | [
"Technology",
"Engineering"
] | 328 | [
"Computer networking",
"Computer science",
"Computer engineering"
] |
71,887,790 | https://en.wikipedia.org/wiki/CQ%20Ursae%20Majoris | CQ Ursae Majoris is a variable star in the northern circumpolar constellation of Ursa Major, abbreviated CQ UMa. It is sometimes identified as HR 5153 from the Bright Star Catalogue or HD 119213 in the Henry Draper Catalogue; CQ UMa is the variable star designation. The star ranges in apparent visual magnitude from 6.28 to 6.30, which is bright enough to be dimly visible to the naked eye. It is located at a distance of 296 light years from the Sun based on parallax measurements.
This object was found to be a chemically peculiar star by W. P. Bidelman in 1964, with the spectrum showing strong lines of the element strontium. (This feature had been previously noted by W. E. Harper in 1937.) A. P. Cowley and C. R. Cowley found abnormalities in both strontium and chromium lines. In 1972, E. W. Burke, Jr. and J. T. Howard discovered the star is variable in luminosity with a period of 1.706 days. S. C. Wolff and N. D. Morrison in 1975 found a longer period of 2.451 days, double the earlier estimate.
W. K. Bonsack in 1974 noted peculiarities with the europium lines and found that the lines of ionized calcium and chromium are variable. Z. Mikulášek in 1978 showed that ionized europium lines varied in antiphase with the ionized chromium lines. In 1981, Y. V. Glagolevskij measured a large magnetic field of CQ UMa, interpreting it to be variable and reversing. Z. Mikulášek was able to fit the observations to an oblique rotator model with a concentration of europium-titanium close to the north magnetic pole, a patch of chromium-strontium near the southern pole, and a belt of enhanced iron along the magnetic equator.
CQ Ursae Majoris is classified as a Alpha2 Canum Venaticorum variable with a stellar classification of A2IVpSrCr. This is a magnetic Ap star where the variability is modulated by the rotation period. It is spinning with a period of 2.449967 days and has an estimated age of approximately 537 million years. The star has double the mass and twice radius of the Sun. It is radiating 19.5 times the Sun's luminosity from its photosphere at an effective temperature of 8,620 K. The magnetic field of CQ UMa is inclined at an angle of 60° and has a dipole field strength of roughly .
References
Further reading
Ap stars
Alpha2 Canum Venaticorum variables
Ursa Major
5153
BD +57 1456
119213
066700
Ursae Majoris, BE | CQ Ursae Majoris | [
"Astronomy"
] | 595 | [
"Ursa Major",
"Constellations"
] |
71,888,296 | https://en.wikipedia.org/wiki/Thallium%28I%29%20nitrate | Thallium(I) nitrate, also known as thallous nitrate, is a thallium compound with the formula TlNO3. It is a colorless and highly toxic salt.
Preparation
Thallium(I) nitrate can be produced by reacting thallium(I) iodide with nitric acid.
However, the production is simpler starting from the metal, its hydroxide or the carbonate:
Toxicity
Thallium(I) nitrate is extremely toxic, like many other thallium compounds. It is highly toxic by ingestion but can also be absorbed through skin due to its solubility in water.
See also
Thallium(III) nitrate
References
Thallium(I) compounds
Nitrates | Thallium(I) nitrate | [
"Chemistry"
] | 150 | [
"Nitrates",
"Oxidizing agents",
"Salts"
] |
71,888,545 | https://en.wikipedia.org/wiki/Sony%20Xperia%205%20IV | The Sony Xperia 5 IV is an Android smartphone manufactured by Sony. Part of Sony's Xperia series, the phone was announced on September 1, 2022.
Design
The Xperia 5 IV is built similarly to the Xperia 1 IV, using anodized aluminum for the frame and Corning Gorilla Glass Victus for the screen and back panel, as well as IP65 and IP68 certifications for water resistance. The build has a pair of symmetrical bezels on the top and the bottom, where the front-facing dual stereo speakers are placed. The right side contains a fingerprint reader embedded into the power button, a volume rocker and a shutter button. The earpiece, front-facing camera, notification LED and various sensors are housed in the top bezel. The bottom edge has the primary microphone, USB-C port, and SIM/microSDXC card slot; the rear cameras are arranged in a vertical strip. The phone is available in three colors: Black, Green and White. Xperia 5 IV marks the last both Xperia 5 series and all Xperia to feature notification LED, as the successor, Sony Xperia 5 V, has removed the feature.
Specifications
Hardware
The Xperia 5 IV is powered by the Qualcomm Snapdragon 8 Gen 1 SoC and an Adreno 730 GPU, accompanied by 8 GB of LPDDR5 RAM. It has 128 or 256 GB of UFS internal storage, which can be expanded up to 1 TB via the microSD card slot with a hybrid dual-SIM setup. The display is a 6.1-inch 1080p (2520 × 1080) HDR OLED with a 21:9 aspect ratio, resulting in a pixel density of 449 ppi. It features a 120 Hz refresh rate, and is capable of displaying one billion colors. The battery capacity is 5000 mAh; USB Power Delivery 3.0 is supported at 30W over USB-C in addition to wireless charging. The device includes a 3.5mm audio jack as well as an active external amplifier.
Camera
The Xperia 5 IV has three 12 MP rear-facing cameras and a 12 MP front-facing camera. The rear cameras consist of a wide-angle lens (24 mm f/1.7), an ultra wide angle lens (16 mm f/2.2), and a telephoto lens (60 mm f/2.4) with 2.5× optical zoom; each uses ZEISS' T✻ (T-Star) anti-reflective coating.
Software
The Xperia 5 IV runs on Android 12. Sony has also paired the phone's camera tech with a "Pro" mode developed by Sony's camera division CineAlta, whose features take after Sony's Alpha camera lineup.
References
Notes
Android (operating system) devices
Flagship smartphones
Sony smartphones
Mobile phones introduced in 2022
Mobile phones with multiple rear cameras
Mobile phones with 4K video recording | Sony Xperia 5 IV | [
"Technology"
] | 607 | [
"Flagship smartphones"
] |
71,888,924 | https://en.wikipedia.org/wiki/Alan%20Seeger%20Natural%20Area | Alan Seeger Natural Area is located in Huntingdon County, Pennsylvania, United States, approximately nine miles south of Boalsburg, within Rothrock State Forest in the Appalachian Mountains. It is traversed by the long-distance Standing Stone Trail, and includes other short trails. The natural area is known for old growth trees and extensive copses of giant rhododendron.
Description
Alan Seeger Natural Area was founded in 1921. It was named after Alan Seeger, a noteworthy American poet who died in action while serving with the French Foreign Legion during World War I in 1916. The name was bestowed as a tribute by Colonel Henry Shoemaker, an early Pennsylvania forestry commissioner, though Seeger is not known to have ever visited the region. A loop trail of about three-quarters of a mile in length visits most of the natural area, with several footbridges over upper tributaries of Standing Stone Creek. The eastern half of this trail is also a segment of the 84-mile Standing Stone Trail. The natural area features extensive copses of giant rhododendron.
The eastern portion of the natural area features several groves of large old growth hemlock and white pine trees of a stature once seen throughout Pennsylvania. Some specimens here are more than 500 years old. These old trees may have survived the Pennsylvania logging era in the late 1800s due to an undefined boundary; two adjoining logging firms would not dare to accidentally fell each other's trees near the boundary between their holdings, thus creating a no-man's land where the trees survived. It is also possible that one or both companies went out of business before these groves of trees were felled, given known logging company practices of the time. Regardless, the natural area now hosts one of the few remaining groves of old-growth trees in Pennsylvania.
See also
List of old growth forests
References
Old-growth forests
Protected areas of Huntingdon County, Pennsylvania | Alan Seeger Natural Area | [
"Biology"
] | 384 | [
"Old-growth forests",
"Ecosystems"
] |
71,888,930 | https://en.wikipedia.org/wiki/CW%20Octantis | CW Octantis, also known as HD 148542, is a solitary, white hued variable star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 6.03, allowing it to be faintly visible to the naked eye. Parallax measurements from Gaia DR3 place the object at a distance of 629 light years. It appears to be receding from the Solar System with a heliocentric radial velocity of .
CW Octantis has a stellar classification of A3 IV, indicating that it is an evolved A-type star heading towards the red giant branch. Zorec and Royer (2012) model it as a dwarf star that has just reached the end of its main sequence lifetime. It has 2.98 times the mass of the Sun and 4.6 times its radius. It radiates 111 times the luminosity of the Sun from its photosphere at an effective temperature of . CW Octantis is estimated to be 188 million years old.
This object is classified as a Alpha2 Canum Venaticorum variable. Most stars of this class have chemical peculiarities in their spectra, but CW Octantis seems to be ordinary. Renson and Manfroid (2009) consider its peculiarity status to be doubtful. Nevertheless, CW Octantis fluctuates between 6.05 and 6.07 in the Hipparcos passband within 2.63 days. It takes 2.8 days to complete a full a rotation, which corresponds to a projected rotational velocity of .
References
Alpha2 Canum Venaticorum variables
Ap stars
A-type subgiants
Octans
Octantis, CW
Octantis, 26
CD-86 00100
148542
83255
6139 | CW Octantis | [
"Astronomy"
] | 363 | [
"Octans",
"Constellations"
] |
71,889,057 | https://en.wikipedia.org/wiki/Chronology%20of%20Haile%20Selassie | This is a chronology of the lifetime of Ethiopian Emperor Haile Selassie (reigned from 1930 to 1974).
1892–1930
23 July 1892 – Haile Selassie (as Ras Tafari) was born from Ras Mekonnen Woldemikael and Woizero Yeshimebet Ali Abba Jifar.
1 November 1905 – Tafari was renamed as Dejazmach at the age of 13.
1906 – His father Ras Mikael died at Kulibi.
1906 – Tafari assumed nominal governorship of Selale, enabled him to continue his studies.
1907 – He was appointed as governor over part of the province of Sidamo.
1907 – Following his death of his brother Yelma, the governorate of Harar was left vacant, which left to Menelik's loyal general Balcha Safo.
1910/1911 – Tafari appointed as governor of Harar.
3 August 1911 – Tafari married to Menen Asfaw from Ambassel, the niece of the heir to throne Lij Iyasu.
1916 – Empress Zewditu made Tafari Ras and was made heir apparent and Crown Prince.
11 February 1917 – During the coronation of Zewditu, she pledged Regent Tafari to rule fairly.
1924 – Ras Tafari toured numerous countries: Jerusalem, Alexandria, Paris, Luxembourg, Brussels, Amsterdam, Stockholm, London, Geneva, and Athens.
1928 – When Dejazmach Balcha Safo went to Addis Ababa with considerable size of forces, Tafari consolidated his hold over the provinces, many of Menelik's appointees refused to abide the new regulations.
18 February 1928 – As Balcha Safo went to Addis Ababa, Tafari had Ras Kassa Haile Darge buy off his army and arranged to have him displaced as the shum of Sidamo Province, by Birru Wolde Gabriel who himself was replaced by Desta Damtew.
2 August 1928 – the Italo-Ethiopian Treaty was signed to foster favorable relations between the two countries.
7 October 1928 – Empress Zewditu crowned Tafari as Negus.
31 March 1930 – Gugsa Welle was defeated by loyal forces of Tafari during the Battle of Anchem.
2 April 1930 – Death of Zewditu; Tafari rose to power as Emperor of Ethiopia.
2 November 1930 – Ras Tafari crowned as Haile Selassie I at Addis Ababa's St. George"s Cathedral.
1930–1974
16 July 1931 – Emperor Haile Selassie introduced the first Constitution of Ethiopia, providing bicameral legislature.
5 December 1934 – the Italians initially invaded Ethiopia at Welwel, in Ogaden; Haile Selassie armies set up headquarters at Dessie in Wollo Province.
3 October 1935 – the Second Italo-Ethiopian War began.
19 October 1935 – Haile Selassie gave more precise orders for his army to his Commander-in-Chief Ras Kassa.
2 May 1936 – Haile Selassie appointed Ras Imru Haile Selassie as Prince Regent in his absence, departing with his family for French Somaliland.
30 June 1936 – Haile Selassie appealed to the League of Nations address the invasion.
1936–1941 – Haile Selassie lived in Bath, England, in Fairfield House, which he bought.
18 January 1941 – during the East African Campaign in World War II, Haile Selassie crossed the border between Sudan and Ethiopia near the village of Um Idda.
5 May 1941 – Haile Selassie entered Addis Ababa and reclaimed his throne after leaving for five years since Italian occupation, and address the Ethiopian populace.
27 August 1942 – Haile Selassie abolished slavery in Ethiopia.
1942 – Haile Selassie attempted to institute a progressive tax scheme.
2 December 1950 – the UN General Assembly adopted Resolution 390 (V), establishing the former Italian colony into Ethiopia.
4 November 1955 – the revised 1955 Constitution of Ethiopia adopted with unitary parliamentary constitutional monarchy scheme.
1958 – the famine of Tigray unveiled to Ministry of the Interior two years later, which contributed significant deaths.
1959 – Haile Selassie played a role of the autocephaly of the Ethiopian Orthodox Tewahedo Church from Coptic Orthodox Church.
13 December 1960 – a coup d'état was attempted against Haile Selassie during state visiting Brazil despite successfully suppressed by his loyal Kebur Zabagna army.
2 December 1950 – The federation of Eritrea with Ethiopia had stipulated under UN Resolution 390 (V).
1961 – Eritrean War of Independence began, followed by the dissolution of the federation and closing of Eritrean parliament.
25 May 1963 – Haile Selassie formed the Organization of African Unity (OAU) headquartered in Addis Ababa.
1964 – Haile Selassie would initiate the concept of the United States of Africa, a proposition later taken up by Muammar Gaddafi.
1966 – Haile Selassie attempted to replace the historical tax system with a single progressive income tax, which weakened the nobility which previously avoided to pay taxes.
1960s – 1970s – Students Marxism revolution took place among educated people with radical and left-wing sentiments to oppose Haile Selassie feudal administration.
1972 – 1974 – the Wollo–Tigray famine killed about 40,000 to 80,000 Ethiopians. Haile Selassie was criticized for not reporting these famines.
12 January 1974 – the Ethiopian Revolution began when Ethiopian soldiers began rebellion in Negele Borena.
27 February 1974 – Prime Minister Aklilu Habte-Wold resigned as a result from mutiny. He installed the liberal aristocrat Endelkachew Mekonnen as a new Prime Minister.
June 1974 – The Coordinating Committee of the Armed Forces, also known as the Derg formed to topple Haile Selassie government.
12 September 1974 – Haile Selassie was deposed by the Derg's General Aman Andom at the age of 82. He was subsequently imprisoned at National Palace in Addis Ababa.
27 August 1975 – Haile Selassie died and pronounced on state media one day later on 28 August from "respiratory failure" following complications from prostate examination followed up by a prostate operation.
17 February 1992 – After the fall of the Derg in 1991, Haile Selassie's bones were found under a concrete slab on the palace grounds.
5 November 2000 – State funeral of Haile Selassie took place at Holy Trinity Cathedral in Addis Ababa.
References
Haile Selassie
Selassie, Haile | Chronology of Haile Selassie | [
"Physics"
] | 1,368 | [
"Spacetime",
"Chronology",
"Physical quantities",
"Time"
] |
71,889,173 | https://en.wikipedia.org/wiki/Mavis%20Freeman%20%28scientist%29 | Mavis Louisa Freeman (30 January 1907 – 1992) was an Australian bacteriologist and biochemist. She assisted Macfarlane Burnet in identifying the source of Q fever.
Early life and education
Mavis Louisa Freeman was born in Ballarat, Victoria on 30 January 1907 to Louisa (née Lutzen) and Harry Stanley Freeman. She completed her primary education at Esperance Girls' School, Brighton where she was dux of classes III and IV. She then attended Firbank Girls' Grammar School where she was dux of the school in 1924. On leaving school she won a scholarship to Trinity College at the University of Melbourne from which she graduated with a BSc in 1928.
Career
Freeman's first job was at the Walter and Eliza Hall Institute where she was employed as a research fellow. Her work included studying snake venoms with Charles Kellaway and proteins with biochemist H. F. Holden.
In 1934 she won the Victorian Women Graduates' Association Travelling Scholarship and went to London to continue her studies at the Lister Institute. She returned to the Walter and Eliza Hall Institute and, in 1939, assisted Macfarlane Burnet in the discovery of the source of Q fever.
In World War II she was appointed as pathologist to the Second Australian Hospital, A.I.F. in Palestine and was the only woman to serve overseas, other than nurses and masseuses.
Freeman returned to the Walter and Eliza Hall Institute after the war but resigned in 1948 and moved to Adelaide to work at the Institute of Medical and Veterinary Research. She completed an MSc at the University of Melbourne in 1950.
Freeman died in Malvern, Victoria in 1992.
References
1907 births
1992 deaths
People educated at Trinity College (University of Melbourne)
Australian bacteriologists
Australian biochemists
20th-century Australian women scientists
20th-century Australian biologists
20th-century Australian chemists
Women bacteriologists
Women biochemists
Australian women biologists
Australian women chemists
People from Ballarat
People educated at Firbank Girls' Grammar School | Mavis Freeman (scientist) | [
"Chemistry"
] | 407 | [
"Biochemists",
"Women biochemists"
] |
71,890,151 | https://en.wikipedia.org/wiki/Vercel | Vercel Inc., formerly ZEIT, is an American cloud platform as a service company. The company maintains the Next.js web development framework.
Vercel's architecture is built around composable architecture, and deployments are handled through Git repositories, the Vercel CLI, or the Vercel REST API. Vercel is a member of the MACH Alliance.
History
Vercel was founded by Guillermo Rauch in 2015 as ZEIT. Rauch had previously created the realtime event-driven communication library Socket.IO. ZEIT was rebranded to Vercel in April 2020, although retained the company's triangular logo.
In June 2021, Vercel raised $102 million in a Series C funding round. As of May 2024, the company is valued at $3.25 billion.
Acquisitions
On December 9, 2021, Vercel acquired Turborepo.
On October 25, 2022, Vercel acquired Splitbee.
Architecture
Deployments through Vercel are handled through Git repositories, with support for GitHub, GitLab, and Bitbucket repositories. Deployments are automatically given a subdomain under the vercel.app domain, although Vercel offers support for custom domains for deployments.
Vercel's infrastructure uses Amazon Web Services and Cloudflare.
Reception
Vercel's clientele includes Airbnb, Uber, GitHub, Nike, Ticketmaster, Carhartt, IBM, and McDonald's.
References
Bibliography
Citations
American companies established in 2015
Companies based in San Francisco
Blog hosting services
Cloud computing providers
Cloud infrastructure
Cloud platforms
Content delivery networks
Free web hosting services
Git (software)
Internet technology companies of the United States
Web service providers
Project hosting websites
Software companies established in 2015 | Vercel | [
"Technology"
] | 376 | [
"Cloud infrastructure",
"Cloud platforms",
"Computing platforms",
"IT infrastructure"
] |
71,890,543 | https://en.wikipedia.org/wiki/John%20Senders | John W. Senders (1920 – Feb 12, 2019) was an American professor of industrial engineering and psychology who did research on safety and human error. He founded Canada's Institute for Safe Medication Practices (ISMP), introduced the visual occlusion paradigm, and organized the first conference on human error, which came to be known as Clambake I.
Early life
Senders was born in Cambridge, Massachusetts, to a family of Russian immigrants with five children. He was the youngest of the five and benefited from an environment full of books, fierce competition, scientific inquiry, and word games. Accepted at age 16 to Antioch College in Yellow Springs, Ohio, he was sent home a year later for his refusal to take a required first-year math course, saying, “I’ve known this stuff since I was 7, and I’ll be damned if I’ll do it again.” In expelling him, the administration made an exception to its famously lenient policies. Years later, he continued his undergraduate education at Harvard. [cite IEEE obituary as source doc]
Education
Senders received an A.B. in experimental psychology from Harvard College in 1948, and a Ph.D. in quantitative psychology from Tilburg University in 1983.
Career
In 1959, Senders was a lecturer in the department of mechanical engineering at the University of Minnesota.
From 1965 to 1972, Senders, was a lecturer and senior research associate in psychology at Brandeis University.
In 1973, Senders took a position as a visiting professor in the department of mechanical and industrial engineering at the University of Toronto. He took a permanent position at the university in 1974 where he worked until he retired in 1985, when he became a Professor Emeritus.
Awards and honors
Due to his recognized contributions in engineering psychology, Senders was welcomed as a full member of the American Psychological Association (APA) long before he had gained a doctoral degree (which used to be a criterion for APA membership) and as a member of the Communications Committee, contributed to development of a National Information System for Psychology in the early 1970s. [11]
In 1973, Senders was elected as a fellow of the American Association for the Advancement of Science.
Senders founded Canada's Institute for Safe Medication Practices (ISMP), and received an award from ISMP in 2001.
In 2008, Senders was awarded the Knowledge Media Design Institute (KMDI) Pioneer Award by the University of Toronto.
In 2010, the Human Factors Interest Group of the University of Toronto held a symposium of Applied Human Factors Research in Senders's honor. Attendees included Abigail Sellen, Neville Moray (remotely), Shuman Zhai, Don Norman, and Jean Zu.
In 2011, Senders won an Ig Nobel Prize in the field of public safety for conducting experiments driving a car while intermittently blindfolded.
Clambake conferences
Senders, along with his wife Ann Chrichton-Harris, organized a meeting in Columbia Falls, Maine in July 1980 of researchers who were interested in studying human error. They originally submitted a proposal for funding the conference to the National Science Foundation, but the proposal was rejected. They decided to invite participants despite the lack of funding, inviting the attendees to attend a clambake. Twenty-five people attended, from the United States and the United Kingdom. This meeting came to be known as the "Clambake Conference" and Clambake I.
In 1983, a multidisciplinary conference on human error was held at the Rockefeller Foundation's Bellagio Center in Bellagio, Italy, funded by NATO and the Rockefeller Foundation. This conference came to be known as Clambake II. Senders, along with Neville Moray, published a summary of the workshop.
In addition to Senders, Chrichton-Harris, and Moray, participants at the clambake conferences included Jens Rasmussen, Daniel Kahneman, Don Norman, James Reason, Alan Swain, Thomas Sheridan, Elizabeth Loftus, Erik Hollnagel, David Woods, Ward Edwards, Brian Gaines, Marcel Kinsbourne, Lawrence Stark, Anne Treisman, Laurence Young, and Dune McRuer.
References
1920 births
2019 deaths
Industrial engineers
Fellows of the American Association for the Advancement of Science
Harvard College alumni
Tilburg University alumni
Ig Nobel laureates
Academic staff of the University of Toronto | John Senders | [
"Engineering"
] | 891 | [
"Industrial engineers",
"Industrial engineering"
] |
71,890,650 | https://en.wikipedia.org/wiki/Thallium%20nitrate | Thallium nitrate may refer to:
Thallium(I) nitrate
Thallium(III) nitrate
Thallium compounds
Nitrates | Thallium nitrate | [
"Chemistry"
] | 30 | [
"Oxidizing agents",
"Nitrates",
"Salts"
] |
71,890,955 | https://en.wikipedia.org/wiki/Al%20Seef | Al Seef () or Al Seef Khor is a 1.8 km waterfront promenade along the bank of Dubai Creek in the Al Fahidi neighborhood of Dubai, United Arab Emirates.
History
The promenade was developed by Dubai-based real estate company Meraas and its construction was completed in 2017.
Reception
Cristiano Luchetti, an associate professor at the American University of Ras Al Khaimah, called this project a "historical fraud" based on a critical interpretation of the usage of components taken from the features of the local architecture of Dubai without sufficient interpretative key and the use of artificially aged finishes and materials.
Similar sentiments are shared by other academicians as the project completely undermines the municipal and cultural authorities' work in preservation and rehabilitation. Moreover, the Al Seef buildings, are an inflated and inaccurate interpretation of the old wind tower houses in Dubai, built of modern materials and aged theatrically to indicate hardship that is not even visible in the initially maintained homes.
Gallery
References
Waterfronts
Architecture in Dubai
Architectural controversies | Al Seef | [
"Engineering"
] | 210 | [
"Architectural controversies",
"Architecture"
] |
67,517,849 | https://en.wikipedia.org/wiki/K-sorted%20sequence | In computer science, a nearly-sorted sequence, also known as roughly-sorted sequence and as -sorted sequence is a sequence which is almost ordered. By almost ordered, it is meant that no element of the sequence is very far away from where it would be if the sequence were perfectly ordered. It is still possible that no element of the sequence is at the place where it should be if the sequence were perfectly ordered.
The nearly-sorted sequences are particularly useful when the exact order of element has little importance. For example Twitter nearly sort tweets, up to the second, as there is no need for more precision. Actually, given the impossibility to exactly synchronize all computers, an exact sorting of all tweets according to the time at which they are posted is impossible. This idea led to the creation of Snowflake IDs.
-sorting is the operation of reordering the elements of a sequence so that it becomes -sorted. -sorting is generally more efficient than sorting. Similarly, sorting a sequence is easier if it is known that the sequence is -sorted. So if a program needs only to consider -sorted sequences as input or output, considering -sorted sequences may save time.
The radius of a sequence is a measure of presortedness, that is, its value indicate how much the elements in the list has to be moved to get a totally sorted value. In the above example of tweets which are sorted up to the second, the radius is bounded by the number of tweets in a second.
Definition
Given a positive number , a sequence is said to be -sorted if for each and for each , . That is, the sequence has to be ordered only for pairs of elements whose distance is at least .
The radius of the sequence , denoted or is the smallest such that the sequence is -sorted. The radius is a measure of presortedness.
A sequence is said to be nearly-sorted or roughly-sorted if its radius is small compared to its length.
Equivalent definition
A sequence is -sorted if and only if each range of length , is -sorted.
Properties
All sequences of length are -sorted, that is, . A sequence is -sorted if and only if it is sorted. A -sorted sequence is automatically -sorted but not necessarily -sorted.
Relation with sorted sequences
Given a sequence a -sorted sequence and its sorted permutation , is at most .
Algorithms
Deciding whether a sequence is -sorted
Deciding whether a sequence is -sorted can be done in linear time and constant space by a streaming algorithm. It suffices, for each , to keep track of and to check that .
Computing the radius of a sequence
Computing the radius of a sequence can be computed in linear time and space. This follows from the fact that it can be defined as .
Halving the radius of a sequence
Given a -sorted sequence , it is possible to compute a -sorted permutation of in linear time and constant space.
First, given a sequence , lets say that this sequence is partitioned if the -smaller elements are in and the -greater elements are in . Lets call partitioning the action of reordering the sequence into a partitioned permutation. This can be done in linear time by first finding the median of and then moving elements to the first or second half depending on whether they are smaller or greater than the median.
The sequence can be obtained by partitioning the blocks of elements at position , then by partitioning the blocks of elements at position , and then again the elements at position for each number such that those sequences are defined.
Using processors, with no shared read nor write access to memory, the same algorithm can be applied in time, since each partition of a sequence can occur in parallel.
Merging two -sorted sequences
Merging two -sorted sequences and can be done in linear time and constant space.
First, using the preceding algorithm, both sequences should be transformed into -sorted sequences.
Let's construct iteratively an output sequence by removing content from both and adding it in .
If both 's are empty, then it suffices to return . Otherwise, let us assume that is empty and not , it suffices to remove the content of and append it to . The case where is empty and not is similar by symmetry.
Let us consider the case where neither is empty. Let us call and , they are the greatest of the -firsts
elements of each list. Let us assume that , the other case is similar by symmetry. Remove
from and remove from and add them to .
Sorting a -sorted sequence
A -sorted sequence can be sorted by applying the halving algorithm given above times. This takes time on a sequential machine, or time using processors.
-sorting a sequence
Since each sequence is necessarily -sorted, it suffices to apply the halving algorithm -times. Thus, -sorting can be done in -time. This algorithm is Par-optimal, that is, there exists no sequential algorithm with a better worst-case complexity.
References
Sorting algorithms | K-sorted sequence | [
"Mathematics"
] | 1,025 | [
"Order theory",
"Sorting algorithms"
] |
67,518,500 | https://en.wikipedia.org/wiki/Initial%20Defense%20Communications%20Satellite%20Program | The Initial Defense Communications Satellite Program or IDCSP was the first United States Department of Defense communications satellite constellation and the first stage of the Defense Communications Satellite Program (DCSP). Launched in five groups by Titan IIIC launch vehicles to near equatorial, subsynchronous orbits between 1966 and 1968, they were intended to be experimental testbeds. They were so successful that, by the time of the launch of the last set of eight satellites, the IDCSP was deemed operational and renamed Initial Defense Satellite Communications System or IDSCS. This system allowed real-time collection of battlefield intelligence during the Vietnam War. A total of 35 IDCSP satellites were launched, 27 successfully.
Background
The Initial Defense Communications Satellite Program or IDCSP was the first stage in the Defense Communications Satellite Program (DCSP) commissioned by United States Secretary of Defense Robert McNamara in 1962. Under the DCSP, several increasingly sophisticated satellite series would test and provide long-range communications between "fixed, transportable or shipboard terminals". Development of these series would be managed by the Defense Communications Agency (DCA). This decision came on the heels of the cancellation of Project ADVENT, the first attempt at a military geosynchronous communications satellite system, begun February 1960. Originally costed at $140 million to develop, $170 million had been spent by 1962, and the estimated total cost had reached $325 million. The cheaper, "interim" IDCSP was chosen to replace ADVENT. It would use a constellation of 24-30 satellites launched into Medium Earth Orbit via ten Atlas Agena rockets for a total cost of $165 million ($60 million of which would be spent on satellites).
Philco's Western Development Division was originally selected by the United States Air Force (USAF) to build the satellites. However, by 1964, the development of the much more powerful Titan IIIC booster made it possible for fewer IDCSP satellites to fulfill the same mission at a higher altitude. Four to eight could be launched on a single Titan IIIC rocket into slightly subsynchronous orbit. Once there, the satellites would be deployed one at a time over the course of three minutes from the Transtage of the Titan. The satellites would drift randomly at an average rate of 28.5° per day becoming a roughly evenly spaced belt of satellites above the Earth's equator. In this way, at least one satellite of the constellation would always be visible to an Earth station if one failed. Full coverage would be provided by at least 12 satellites.
Thus, the Titan IIIC was chosen to replace the Atlas Agena as the IDCSP launch vehicle. This change did not go unchallenged; the House Committee on Government Operations denounced the move, saying that the "plan for short-range economies depending on a high-risk program may prove costly in the end". With the selection of the Titan IIIC as the IDCSP booster, the Pentagon dropped contract negotiations with Philco, preferring to develop the satellites in-house. Through early 1965 the satellites were still being designed so that they could be lofted to Medium Earth Orbit via Atlas Agena in the event that the Titan IIIC was not available.
The Titan IIIC was developed in time for use, the first launch taking place just four months behind the original schedule. The satellites built by 1966, sufficient for three launches, had cost just $33 million to produce (an overage of $3 million on original estimates).
Design
Developed primarily by TRW, the IDCSP spacecraft were identical communications satellites, spin-stabilized, 26-sided polygons, in diameter, covered with solar panels, and had a mass of . They were specifically designed to be simple to avoid the problems faced by the earlier Courier and Advent programs: no in-orbit control mechanisms were included, nor were the satellites equipped with batteries. The satellites were equipped with an automatic radiation shut-off device to deactivate them after six years in orbit.
Each satellite contained a single 3.5 Watt X-band or SHF transponder receiving at 8.025 GHz and transmitting 7.25–7.3 GHz (similar to the Lincoln Experimental Satellites procured around the same time) capable of concurrently supporting 600 voice or 6000 teletype conversations. Complementing these satellites were ground communications terminals used to transmit and receive via IDCSP satellite voice, imagery, computerized digital data, and teletype channel using Frequency-division multiplexing/Frequency Modulation (FDM/FM), Differential Phase Shift Keying (DPSK), Multiple frequency-shift keying (MFSK), and Spread Spectrum Multiple Access (SSMA) modulation techniques. The Eimac Division of Varian Associates supplied one of the two traveling wave amplifiers used by the satellite's transmitter, the other being produced by Watkins-Johnson Company. Because of the low power of the satellites' transponders, as well as its low-gain antenna, the receiving installations had to be very large.
Operational history
The first launch of IDCSP satellites took place at 14:00:01 GMT on 16 June 1966 from Cape Canaveral Space Launch Complex 41 aboard the fourth Titan IIIC. After a successful Transtage burn placed the last stage of the Titan into a by orbit, the first seven IDCSP satellites (along with the Gravity Gradient Technology Satellite, a stabilization test satellite built on the same satellite bus) were dispersed one-by-one into orbit, each drifting 27.8° per day. Communications were conducted successfully between Fort Dix, New Jersey, and sites in California, England and Germany.
The second set of IDCSP satellites, totaling eight, was lost 26 August 1966 when a faulty payload fairing caused the launch failure of the fifth Titan IIIC. This proved to be the last unsuccessful Titan IIIC launch.
On 18 January 1967, the seventh Titan IIIC launch successfully placed a full constellation of eight IDCSP satellites into orbit, and on 1 July 1967, four more IDCSP satellites (including IDCSP 19, also known as DATS (Despun Antenna Test Satellite)) were put into orbit. IDCSP ground terminals had been installed at American bases at Saigon and Nha Trang by that time. Despite the comparative simplicity of the IDCSP constellation satellites, under Project Compass Link, the satellites made it possible for high-resolution photography to be transferred between the South Vietnamese capital and Washington, D.C., allowing near-real-time battlefield analysis. With the launch of the fourth system of eight satellites on 13 June 1968, DCA deemed the experimental system operational, renaming it the Initial Defense Satellite Communications System (IDSCS). This system afforded the American military a secure system for sensitive command-and-control communications, the more routine administrative and logistical messages being relayed via commercial satellites. The IDCSP constellation was also used by North Atlantic Treaty Organization states, which referred to the program as NATO-1.
In all, 35 IDCSP satellites were launched in 5 groups by Titan IIIC launch vehicles, 27 successfully to near equatorial, subsynchronous orbits. The automatic shut-off device installed on the IDCSP satellites did not work reliably, and many satellites operated long past their six-year lifespan. As of 1975, six were still functioning.
Technical and systems management assistance was provided to the USAF's Space Systems Division by The Aerospace Corporation. The IDCSP series was succeeded by the NATO-2 and DSCS-2 true geosynchronous satellites.
Launches
References
1966 in spaceflight
1967 in spaceflight
1968 in spaceflight
Communications satellite constellations
Military communications
Military space program of the United States
Satellite series
Spacecraft launched by Titan rockets
Military equipment introduced in the 1960s | Initial Defense Communications Satellite Program | [
"Engineering"
] | 1,582 | [
"Military communications",
"Telecommunications engineering"
] |
67,518,897 | https://en.wikipedia.org/wiki/Sklyanin%20algebra | In mathematics, specifically the field of algebra, Sklyanin algebras are a class of noncommutative algebra named after Evgeny Sklyanin. This class of algebras was first studied in the classification of Artin-Schelter regular algebras of global dimension 3 in the 1980s. Sklyanin algebras can be grouped into two different types, the non-degenerate Sklyanin algebras and the degenerate Sklyanin algebras, which have very different properties. A need to understand the non-degenerate Sklyanin algebras better has led to the development of the study of point modules in noncommutative geometry.
Formal definition
Let be a field with a primitive cube root of unity. Let be the following subset of the projective plane :
Each point gives rise to a (quadratic 3-dimensional) Sklyanin algebra,
where,
Whenever we call a degenerate Sklyanin algebra and whenever we say the algebra is non-degenerate.
Properties
The non-degenerate case shares many properties with the commutative polynomial ring , whereas the degenerate case enjoys almost none of these properties. Generally the non-degenerate Sklyanin algebras are more challenging to understand than their degenerate counterparts.
Properties of degenerate Sklyanin algebras
Let be a degenerate Sklyanin algebra.
contains non-zero zero divisors.
The Hilbert series of is .
Degenerate Sklyanin algebras have infinite Gelfand–Kirillov dimension.
is neither left nor right Noetherian.
is a Koszul algebra.
Degenerate Sklyanin algebras have infinite global dimension.
Properties of non-degenerate Sklyanin algebras
Let be a non-degenerate Sklyanin algebra.
contains no non-zero zero divisors.
The hilbert series of is .
Non-degenerate Sklyanin algebras are Noetherian.
is Koszul.
Non-degenerate Sklyanin algebras are Artin-Schelter regular. Therefore, they have global dimension 3 and Gelfand–Kirillov dimension 3.
There exists a normal central element in every non-degenerate Sklyanin algebra.
Examples
Degenerate Sklyanin algebras
The subset consists of 12 points on the projective plane, which give rise to 12 expressions of degenerate Sklyanin algebras. However, some of these are isomorphic and there exists a classification of degenerate Sklyanin algebras into two different cases. Let be a degenerate Sklyanin algebra.
If then is isomorphic to , which is the Sklyanin algebra corresponding to the point .
If then is isomorphic to , which is the Sklyanin algebra corresponding to the point .
These two cases are Zhang twists of each other and therefore have many properties in common.
Non-degenerate Sklyanin algebras
The commutative polynomial ring is isomorphic to the non-degenerate Sklyanin algebra and is therefore an example of a non-degenerate Sklyanin algebra.
Point modules
The study of point modules is a useful tool which can be used much more widely than just for Sklyanin algebras. Point modules are a way of finding projective geometry in the underlying structure of noncommutative graded rings. Originally, the study of point modules was applied to show some of the properties of non-degenerate Sklyanin algebras. For example to find their Hilbert series and determine that non-degenerate Sklyanin algebras do not contain zero divisors.
Non-degenerate Sklyanin algebras
Whenever and in the definition of a non-degenerate Sklyanin algebra , the point modules of are parametrised by an elliptic curve. If the parameters do not satisfy those constraints, the point modules of any non-degenerate Sklyanin algebra are still parametrised by a closed projective variety on the projective plane. If is a Sklyanin algebra whose point modules are parametrised by an elliptic curve, then there exists an element which annihilates all point modules i.e. for all point modules of .
Degenerate Sklyanin algebras
The point modules of degenerate Sklyanin algebras are not parametrised by a projective variety.
References
Abstract algebra | Sklyanin algebra | [
"Mathematics"
] | 933 | [
"Abstract algebra",
"Algebra"
] |
67,520,139 | https://en.wikipedia.org/wiki/Run%20of%20a%20sequence | In computer science, a run of a sequence is a non-decreasing range of the sequence that cannot be extended. The number of runs of a sequence is the number of increasing subsequences of the sequence. This is a measure of presortedness, and in particular measures how many subsequences must be merged to sort a sequence.
Definition
Let be a sequence of elements from a totally ordered set. A run of is a maximal increasing sequence . That is, and assuming that and exists. For example, if is a natural number, the sequence has the two runs and .
Let be defined as the number of positions such that and . It is equivalently defined as the number of runs of minus one. This definition ensure that , that is, the if, and only if, the sequence is sorted. As another example, and .
Sorting sequences with a low number of runs
The function is a measure of presortedness. The natural merge sort is -optimal. That is, if it is known that a sequence has a low number of runs, it can be efficiently sorted using the natural merge sort.
Long runs
A long run is defined similarly to a run, except that the sequence can be either non-decreasing or non-increasing. The number of long runs is not a measure of presortedness. A sequence with a small number of long runs can be sorted efficiently by first reversing the decreasing runs and then using a natural merge sort.
References
Sorting algorithms | Run of a sequence | [
"Mathematics"
] | 304 | [
"Order theory",
"Sorting algorithms"
] |
67,521,729 | https://en.wikipedia.org/wiki/Nirmatrelvir | Nirmatrelvir is an antiviral medication developed by Pfizer which acts as an orally active 3C-like protease inhibitor. It is part of a nirmatrelvir/ritonavir combination used to treat COVID-19 and sold under the brand name Paxlovid.
Development
Pharmaceutical
Coronaviral proteases cleave multiple sites in the viral polyprotein, usually after there are glutamine residues. Early work on related human rhinoviruses showed that the flexible glutamine side chain in inhibitors could be replaced by a rigid pyrrolidone. These drugs had been further developed prior to the COVID-19 pandemic for other diseases including SARS. The utility of targeting the 3CL protease in a real world setting was first demonstrated in 2018 when GC376 (a prodrug of GC373) was used to treat the previously 100% lethal cat coronavirus disease, feline infectious peritonitis, caused by feline coronavirus. Nirmatrelvir and GC373 are both peptidomimetics, share the aforementioned pyrrolidone in P1 position and are competitive inhibitors. They use a nitrile and an aldehyde respectively to bind the catalytic cysteine. Pfizer investigated two series of compounds, with nitrile and benzothiazol-2-yl ketone as the reactive group, respectively, and in the end settled on using nitrile.
Nirmatrelvir was developed by modification of the earlier clinical candidate lufotrelvir, which is also a covalent protease inhibitor but its active element is a phosphate prodrug of a hydroxyketone. Lufotrelvir needs to be administered intravenously, limiting its use to a hospital setting. Stepwise modification of the tripeptide peptidomimetic led to nirmatrelvir, which is suitable for oral administration. Key changes include a reduction in the number of hydrogen bond donors, and the number of rotatable bonds by introducing a rigid bicyclic non-canonical amino acid (specifically, a "fused cyclopropyl ring with two methyl groups"), which mimics the leucine residue found in earlier inhibitors. This residue had previously been used in the synthesis of boceprevir.
Tert-leucine (abbreviation: Tle) used in the P3 position of nirmatrelvir was identified first as optimal non-canonical amino acid in potential drug targeting SARS-CoV-2 3C-like protease using combinatorial chemistry (hybrid combinatorial substrate library technology). The leucine-like residue resulted in loss of a nearby contact with a glutamine on the 3C-like protease. To compensate, Pfizer tried adding methane sulfonamide, acetamide and trifluoroacetamide, discovering that of the three, trifluoroacetamide resulted in superior oral bioavailability.
Chemistry and pharmacology
Full details of the synthesis of nirmatrelvir were first published by scientists from Pfizer.
In the penultimate step a synthetic homochiral amino acid is coupled with a homochiral amino amide using the water-soluble carbodiimide EDCI as a coupling agent. The resulting intermediate is then treated with Burgess reagent, which dehydrates the amide group to the nitrile of the product.
Nirmatrelvir is a covalent inhibitor, binding directly to the catalytic cysteine (Cys145) residue of the cysteine protease enzyme.
In the co-packaged medication nirmatrelvir/ritonavir, ritonavir serves to slow the metabolism of nirmatrelvir via cytochrome enzyme inhibition, thereby increasing the circulating concentration of the main drug. This effect is also used in HIV therapy, where ritonavir is used in combination with another protease inhibitor to similarly enhance their pharmacokinetics.
Society and culture
Licensing
In November 2021, Pfizer signed a license agreement with the United Nations–backed Medicines Patent Pool to allow nirmatrelvir to be manufactured and sold in 95 countries. Pfizer stated that the agreement will allow local medicine manufacturers to produce the pill "with the goal of facilitating greater access to the global population". The deal excludes several countries with major COVID-19 outbreaks including Brazil, China, Russia, Argentina, and Thailand.
Names
Nirmatrelvir is the international nonproprietary name
Research
The research that led to nirmatrelvir began in March 2020, when Pfizer formally launched a project at its Cambridge, Massachusetts site to develop antiviral drugs for treating COVID-19. In July 2020, Pfizer chemists were able to synthesize nirmatrelvir for the first time. In September 2020, Pfizer completed a pharmacokinetic study in rats which suggested that nirmatrelvir could be administered orally. The actual synthesis of the drug for laboratory research and for clinical trials was carried out at Pfizer's Groton, Connecticut site.
In February 2021, Pfizer launched the company's first phase I trial of PF-07321332 (nirmatrelvir) at its clinical research unit in New Haven, Connecticut.
A study published in March 2023 reported that treatment with nirmatrelvir within five days of initial infection reduced the risk of long COVID relative to patients who did not receive Paxlovid.
A 2024 study found that "the time to sustained alleviation of all signs and symptoms of Covid-19 did not differ significantly between participants who received nirmatrelvir–ritonavir and those who received placebo."
References
Amides
COVID-19 drug development
Cyclopropanes
Nitriles
Drugs developed by Pfizer
Pyrrolidones
SARS-CoV-2 main protease inhibitors
Trifluoromethyl compounds | Nirmatrelvir | [
"Chemistry"
] | 1,272 | [
"Amides",
"Drug discovery",
"Functional groups",
"COVID-19 drug development",
"Nitriles"
] |
67,521,816 | https://en.wikipedia.org/wiki/Leohumicola%20verrucosa | Leohumicola verrucosa is a heat-resistant, endophytic, ericoid mycorrhizal soil fungus. Its species name refers to rough, warty or spine-like ornamentations on its aleurioconidia. L. verrucosa was first described from samples of soil exposed to fire; among these it was especially abundant in regularly burned blueberry fields in eastern Canada. L. verrucosa forms mycorrhizal relationships with a wide variety and distribution of species in the Ericaceae family.
Description and morphology
The sexual structures of L. verrucosa have not been seen or studied; instead, this species is identified by the mature morphology and development of its asexual aleurioconidia, as well as genetic data.
The aleurioconidia of L. verrucosa have a basal and terminal cell connected by a small pore; this is a characteristic shared by all described members of the genus Leohumicola. Oftentimes in their initial stages of development, aleurioconidia are simply clear, cylindrical extensions of conidiogenous hyphae. Later in development, a septum develops between the aleurioconidia and the conidiogenous hypha. As the terminal aleurioconidial cell swells, it takes on a dark-brown color. Its cell walls sometimes remain smooth and slightly thicken, but more often they become roughened with the wart or spine-like projections characteristic of this species, with the projections concentrated near the top of the terminal aleurioconidial cell. The basal cell remains clear or takes on a pale brown color as it swells. When development of the aleurioconidia is complete, it is released from the conidiogenous hypha on which it was formed by rhexolytic secession; the ruptured basal cell remains attached to the dispersed terminal cell.
The conidiogenous hyphae, often forming in the aerial mycelium of the colony, display a range of forms.
Most commonly, they develop sympodial proliferations, producing up to five clusters of denticles. They may also form once- or twice-branched conidiophore-like structures, or develop as single denticles.
The mycelium of L. verrucosa colonies can be greyish yellow, olive yellow, or gray, and colonies produce red, reddish brown, or olive brown soluble pigments.
Leohumicola verrucosa forms endophytic hyphal coils in rhizodermal cells of the fine roots of Vaccinium virgatum. These endophytic hyphae tend to be looser in living host cells and denser in non-living host cells, a pattern that is consistent with other ericoid mycorrhizal fungi. L. verrucosa also forms hyphae between, within, and outside of rhizodermal cells.
Taxonomy
Leohumicola verrucosa was described in 2005 by Nickerson et al., alongside three other Leohumicola species and the genus itself in Hambleton et al. 2005. Its species name references
its characteristically verrucose aleurioconidia. It was first isolated from soil samples in Nova Scotia, Canada; Alberta, Canada; and Puerto Rico. Nearly all of the soil samples from which this fungi were initially isolated and described were previously exposed to fire. This species does not have any synonyms, nor has its classification changed since its description in 2005.
Leohumicola verrucosa is the type species of the genus Leohumicola. All members of the Leohumicola genus produce two-celled aleurioconidia, grow slowly, and only sporulate sparsely, if at all.
Other described members of this genus include:
Leohumicola atra
Leohumicola incrustata
Leohumicola levissima
Leohumicola lenta
Leohumicola minima
Leohumicola terminalis
Phylogenetic analyses of nuclear DNA sequences encoding the SSU and ITS ribosomal genes also grouped some undescribed GenBank sequences in this monophyletic genus. The Cox1 gene has since been sequenced for Leohumicola. Phylogenetic analyses place the monophyletic Leohumicola genus in the class Leotiomycetes. Its closest relatives in this class are other soil and root-associated fungi.
Distribution, habitat, and ecology
Leohumicola verrucosa was first described from soil sampled in Canada and Puerto Rico. The distance between these initial sites led the researchers who described this species to propose that it may have a broad distribution. Indeed, since its description, L. verrucosa has been isolated from Rhododendron molle roots and soil on Mt. Nekodake, Japan; Vaccinium myrtillus roots in boreal forest in northern Sweden; forest floor soil in a wet sclerophyll forest near Geeveston, Tasmania, Australia; soil from remnant temperate grassland near Melbourne, Australia; and soil samples from the Andes mountain range in Argentina, among other sites. Two characteristics that are common among many of these sampling localities are the presence of plants in the Ericaceae family, and/or the recent exposure of the soil to heat via fire.
Leohumicola verrucosa has been isolated at elevations as low as approximately sea level and as high as 3,000 meters, and from a range of habitats with widely varying soil compositions and plant communities, including forests, grasslands, commercial agricultural fields, and even coastal dunes. As a thermo-tolerant ericoid mycorrhizal soil fungus, L. verrucosa has a particular advantage in colonizing regularly burned plant communities in which the Ericaceae family is represented by at least one species. We do not yet understand the mechanism of heat resistance in L. verrucosa.
The status of L. verrucosa as an ericoid mycorrhizal fungus is still considered putative by some, though observations of intracellular hyphal coils in Ericaceae root cells, records of associations with a wide variety of Ericaceae plants in situ, and evidence of L. verrucosa's ability to readily colonize Ericaceae roots, especially after heat treatment of soil, all provide support for the role of this species as an endophytic, ericoid mycorrhizal fungus. Research demonstrates that the mycorrhizal symbioses between L. verrucosa and Ericaceae plants may be mutualistic. For example, Vaccinium myrtilloides and Ledum groenlandicum individuals grown in heated soil colonized by L. verrucosa had higher root and shoot biomass than individuals grown in unheated, sterile soil. Another study demonstrated that, when colonized by ericoid mycorrhizal fungi including L. verrucosa, the plant species Calluna vulgaris and Rhododendron hirstum had a decreased rate of pathogenic fungal infection as compared to treatments not colonized by ericoid mycorrhizal fungi.
Uses
Although L. verrucosa does not directly provide food or economic value to humans, it has been shown to form mutualistic mycorrhizal relationships with plants that do, including lingonberries and various species of agriculturally-important blueberries. L. verrucosa also forms mutualistic mycorrhizal relationships with Ledum groenlandicum, an ericoid species with cultural, nutritional, and/or medicinal importance to many of the indigenous peoples of North America, including the Ojibwe, Potawatomi, Cree, and Mi'kmaq; many Inuit groups; and nearly all of the indigenous peoples who originally inhabited the land we call British Columbia, Canada.
Further research on the compounds produced by L. verrucosa may yet reveal that they are of medical value to humans. Phenolic compounds produced by the closely related Leohumicola incrustata, were shown to be effective in inhibiting the growth of two strains of gram-negative bacteria, and one proposed explanation for L. verrucosa's own role in inhibiting pathogenic fungal colonization of ericoid roots is that it has an antibiotic mechanism which may be of interest to human medicine.
Soil fungi, and especially mycorrhizal fungi that form mutualistic symbioses with native plant species, are important components of ecological restoration projects. The isolation of L. verrucosa in remnant temperate grasslands of Australia supports its role in the health and diversity of this conserved ecosystem's microbiome. The mutualistic mycorrhizal relationship between L. verrucosa and the naive plant species Vaccinum myrtilloides and Ledum groenlandicum has identified it as a candidate of interest for assisting these plant species in revegetating an oil sand mine in Alberta, Canada that was once boreal forest.
References
Leotiomycetes
Fungal plant pathogens and diseases
Fungus species | Leohumicola verrucosa | [
"Biology"
] | 1,881 | [
"Fungi",
"Fungus species"
] |
67,521,820 | https://en.wikipedia.org/wiki/Water%20use%20in%20alluvial%20fans | Water use in alluvial fans refers to irrigation systems using the water resources in alluvial fans, mainly river floods and groundwater recharged by infiltration of rain or river water, to enhance the production of agricultural crops.
Background
Alluvial fans, also called inland deltas, occur at the foot of mountain ranges and mark the presence of river floods. They contain considerable groundwater reservoirs that are replenished each year by infiltration of the water from the river branches into the usually permeable underground, thus creating rich aquifers.
The mountainous areas usually receive more rainfall than the plains: they form a watershed and provide a source of water. In (semi)arid regions, therefore, alluvial fans are often used for irrigation of agricultural crops. The fans reveal much greenery in the harsh desert-like environment. Irrigation methods in alluvial fans differ according to the hydrological regime of the river, the shape of the fan, and the natural resources available to maintain human life.
Examples
Khuzdar
The alluvial fans along the river plains near Khuzdar, Baluchistan, are fed by small water catchments in areas of relatively low mountains. The fans are relatively small, steep, and subject to flash floods
Average annual rainfall in Baluchistan varies between 200 and 400 mm, depending on altitude, and the main part occurs in winter (November to March). Of old, in sloping lands, farmers constructed bunds along the contour lines to capture the surface runoff (Fig. K1). This method of water harvesting (locally called khuskaba) provided extra water for agricultural crops planted just up-slope of the bund, where the captured water would infiltrate into the soil and provide extra soil moisture to supplement the scarce rainfall.
In alluvial fans, the spate floods provided and additional source of water. The floods, diverted from the watercourses, were retained behind similar bunds employed in the khuskaba system (Fig. K2). The method of flood interception is locally called sailaba (Rod Kohi elsewhere in Pakistan, generally: spate irrigation). The system is combined with the tapping of groundwater from the aquifer by means of dug underground galleries, called karez or qanat (Fig. K3). The karezes make permanent agriculture possible (Fig. K3).
Although the sailaba-and-qanat systems cover about 20% of the agricultural land, their production is more than 40% of the total.
It is a modern development to sink deep wells in the aquifer of the alluvial fan to exploit the groundwater more effectively than do the traditional karezes. The owners of the wells may be entrepreneurs from elsewhere and the original population runs the risk of losing the karez water when the wells draw the water table down to a deeper depth than that of the karezes so that these fall dry (Fig K4).
Garmsar
The fairly large alluvial fan of Garmsar, east of Tehran, is fed by the Hableh Rud river with an important catchment area in the high Alburz mountain range. The river carries a large amount of water during the rainy season, otherwise the discharge is low.
The irrigation system for the Garmsar alluvial fan is quite well developed (Fig. G1, below), to the extent that lined canals have been made and a large belt-canal crosses the fan through its middle.
Roughly, the cropped area occupies 30% of the land each season, while 70% is left fallow. The winter crops are mainly wheat and barley, while the summer crops are cotton and melons. However, the planting of the new crops is done before harvesting the previous crops. Thus, there is a period of overlap during which 60% of the land is under crops. The fallow land is continuously rotated throughout the years, so that there exists no permanent fallow land, except along the fringes at the base of the fan where soil salinization occurs.
An estimated average annual water balance is shown in Fig. G2 (below). It is seen that the storage of irrigation losses in the aquifer plays an important role. In the dry season the groundwater is used for irrigation by pumping from deep wells. A cross-section of the groundwater situation is shown in Fig. G3 (below).
The water rights are expressed in sang, a measure of continuous flow of about 10 L/s, but in practice it varies from 10 to more than 15 L/s. The water is delivered to about 100 tertiary units (often a village), within which the water is distributed by 12-day rotations amongst the farmers who each are entitled to receive the authorized sangs for a fixed number of hours during each rotation period. The village communities are, at the same time, water-user associations who take care of the water-distribution within the tertiary unit and they maintain the tertiary canals.
At present, the distribution of surface irrigation water to the villages is determined by the Garmsar Water Authority on the basis of the water rights and verbal agreements and communications with the water users in the absence of a written manual. The authority also maintains the irrigation canals and structures. The structures are sometimes re-designed to adjust them to verbally communicated needs. The fair distribution of the irrigation water is not an easy job as the average annual river discharge is quite variable in the range of 5 to 20 m3/s (see graph at the right).
The deep tube-wells are privately owned. The drilling of wells is subject to license. Recently, the licensing has stopped for fear of over-exploitation of the aquifer. It appears that no operational rules are applied to the wells.
In the fringe lands, the water table is shallow because the discharge capacity of the aquifer diminishes here for two reasons: (1) the hydraulic gradient reduces where the sloping alluvial fan reaches the flat desert area, and (2) the thickness and hydraulic conductivity of the aquifer diminishes. The necessary drainage canals for watertable control at the fringes of the irrigation perimeter are not maintained by the water authority, but by the respective farmers groups. For the irrigation water, these groups depend (1) on occasional river floods too large to be handled by the irrigation system and that flow down to the fringe lands through the natural watercourses, (2) on spillage from the irrigation system, and (3) on deep wells.
To stabilize the agriculture in the fringe lands, which are threatened by soil salinization, a method of strip-cropping (Fig. G4) can be recommended for soil salinity control. This method uses irrigated strips next to permanently un-irrigated strips, whereby the salinization is directed to the un-irrigated strips. This concept is sometimes called sacrificial drainage.
Punata
The alluvial fan of Punata in the Valle Alto, east of Cochabamba, is fed by the Rio Paracaya river with a higher average discharge than the Hableh Rud, and consequently is fairly flat.
The alluvial fan of Punata is found in the district of Cochabamba, Bolivia.
The region of Punata, at the upper end of the Valle (valley) Alto, at about 2800 m altitude, has a summer rainfall of 400 to 450 mm starting in the second half of November end ending in March. Maize is here the most important food crop, followed by potatoes. Alfalfa is the dominant fodder crop, followed by maize straw. (Fig. P1). These crops could, of old, only be planted successfully because of the existence of additional water resources like runoff, floods, river base-flow and groundwater. In the winter months, crop growth is restricted due to the occurrence of night frosts, especially in June and July, and absence of rains.
The total rural population in Punata is estimated at 25 000. There are about 4000 families of which an estimated 3680 are farmer families. The farms are small. The average size is 1.3 ha of which 1 ha is cropped. The modal size of farm is smaller, about 0.7 ha.
The rainfall distribution in Punata is characterized by a wet season from December to March, a dry season from May to October, and transition months in April and November. The average yearly total is 428 mm (1966 to 1983, San Benito). The rainfall with a probability of exceedance of 75% (R75) on a year basis is 360 mm. Rainfall is not reliable: in the period from 1966 to 1983, the yearly total varied between 246 mm (1982/83) to 591 mm (1968/69).
The river floods during the rainy summer period can be used for irrigation by anyone who wants to. When the river flow recedes, the stream can only be used for rotational irrigation by those who are entitled to take part in it (this is locally called the mita system). By the month of May the river base-flow becomes strongly reduced, and a drought period sets in, lasting into November.
Irrigation is considered desirable to start the cropping season in August/September, so that an early harvest can be obtained. The early harvest has a high market value and reduces peak labor requirements. Further, the irrigation reduces the risk of crop failure and it permits diversification of agricultural produce. Nevertheless, there are some farming communities that have refrained in the past from the extra effort to obtain additional irrigation water and who seemed to be content with purely rain-fed cropping.
At a modest scale, irrigation from deep-wells is also practiced.
In order to satisfy the needs of the majority of the farmers who strongly wish to have additional irrigation water, the irrigation project Punata-Tiraque began to be developed from 1970 onwards. The project entailed the construction of a complicated system of dams and reservoirs up in the Andean mountains (Fig. P2).
The gross area of the Punata projects is estimated at 4600 ha, 90% of which can be used for agriculture or animal husbandry. About 1150 ha of this presently receive irrigation water, either surface water derived from the Laguna Robada or Lluska Kocha dam, or water pumped from the 16 deep wells in the project area (estimated at 350 ha). In addition there are a few hundred hectares that receive occasional water from mita irrigation (wild flooding).
The traditional irrigation method is based on handling large irrigation flows (golpes) per farm at large intervals. The intake structures in the Pucara Mayu river, at the place where it enters the alluvial fan of Punata, would alternately pass water from each of the reservoir systems (Laguna Robada and Lluska Kocha / Muyu Loma) and the natural mita water. The new system has been designed for smaller flows with shorter rotation intervals, but it works continuously for the whole area, so that there is no need anymore to separate the various sources of water. It covers a much larger area than the traditional system and it incorporates the associations of the mita systems (which may have partly the same members), the associations of tube-well systems (which may also have partly the same members) as well as the persons who had no previous water rights.
Hence, the new irrigation system makes it necessary to replace the traditional water rights by a totally new set of rights (and duties). In addition, the farmers will have to get used to new water distribution methods and new field irrigation techniques. Because the new irrigation zones do not correspond to the boundaries of the existing, scattered, Comité’s de Riego (Fig. P3), not only the water management but also the organizational structure will have to be adjusted to the new situation.
Okavango
The Okavango inland delta, near Maun, receives an enormous amount of river inflow from Angola. Hence, the fan is so large and flat that it is rather called a delta. It takes six months for the peak inflow at the apex to reach the base of the delta.
Features
The inland Okavango Delta in northwest Botswana is hand-shaped, with the fingers spread (see map). The Okavango River, which originates in Angola, enters the delta at its apex. On the average, the river carries about 10 000 million m3 of water a year into the delta. The flow rate is high in the months of March and April (about 1000 m3 /s on the average), but varying from year to year between 500 and 1500 m3/s and low in November (100 to 200 m3 /s).
The large volume of water spreading over the delta is almost fully absorbed in permanent and seasonal swamps (the latter are called molapo’s) before is slowly infiltrates or evaporates. There is rich swamp vegetation, which creates an ideal environment for numerous kinds of animals. The rich fauna finds its habitat on and between the thousands of islands between the swamps.
The little water that exceeds the retention capacity of the marshy wilderness drains from July to November through the fingers of the giant hand. Hence, it takes almost six months before the peak discharge of the Okavango River manifests itself at the base of the delta. Here, the water meets a barrier: the Thamalakane Fault Line (see map), beyond which the Kalahari sands rise up 10 m. At the foot of the fault, the Thamalakane River collects the water (which is not more than 5% of the total inflow) and carries it almost without gradient to the Boteti River, which flows through a breach in the fault line. Eventually, the remaining waters evaporate in the Makgadikgadi Pans, more than 200 km to the east.
Although the annual rainfall is relatively low (an average of 500 mm, the greater part of which falls from December to March), it contributes a volume of water to the Delta equaling half of the Okavango inflow. The annual rainfall and its yearly distribution are equally erratic as the regime of the river.
The Okavango River transports a large amount of sands and other sediments into the delta. Their mass is about 2 million tons a year. Salts also enter the Delta, but they do so in a dissolved form. The salt concentration of the water is some 200 mg/L, which is very low. The total weight of incoming salts is thus about 2 million tons per year.
The sediments and the salts imported by the Okavango River settle in the delta. Together with the vegetation the sediments build up resistances to surface-water flow. As a result, the main watercourses have in the past swayed from thumb to little finger to and fro, as is common in alluvial fans. Tectonic movements have also contributed to this phenomenon. At present the middle finger, from which the Boro River stems, provides the major thoroughfare.
Many of the islands in the delta have a garland of riparian trees along their borders, but in the middle they are bare: symptoms of salt accumulation (see photo of the delta).
The Kalahari Desert cooperates with the Okavango River to form the predominantly sandy soils of the delta. The desert uses the vector wind to deposit its share of fine sand.
The geophysical characteristics of the Okavango Delta have led to a low population density, so that the natural situation has scarcely been disrupted by mankind. Also, the population was more interested in hunting and cattle breeding than in food crop production, so that agricultural developments were limited.
The arable lands in the south-eastern fringes of the delta, that become dry after the floods recede (these are locally known as molapo's), often have a sandy topsoil. In depressions, the topsoil may be thin or missing altogether, exposing a heavy clay soil.
Developments
In 1978/79, after four years of high and prolonged floods had made molapo farming impossible, a severe drought coincided with an outbreak of foot and mouth disease, leaving the local population in a state of emergency. This resulted in two important undertakings:
The first took place from 1979 to 1981 when, as part of a drought-relief program (Food for Work), FAO organized labor-intensive works to rehabilitate the flood-control bunds that the local population had built to protect their crops against inundations from rainstorms. Some new bunds were also built.
The second was the construction of the “Buffalo-fence” (see map), which separates the outer fringes of the delta from its interior to prevent the spread of cattle diseases – especially foot and mouth disease. Completed in 1983, this fence has increased the importance of the molapo’s outside it, and for the following reasons. Especially in the years when rains start late, the new grass flush in the molapo’s after flood-recession presents about the only source of fodder in the region, also for the herds in the wide surroundings of the delta. With the molapo’s inside the fence closed to cattle grazing, the grazing intensity in the molapo’s outside the fence has increased.
The Molapo Development Projects (MDP) became operational in December 1983. The project aimed at increasing crop production in pilot areas by protecting those areas against prolonged high floods by flood-control bunds with entrance gates that could be closed (see photo). When enough floodwater has entered the molapo, the gate can be closed and the water recedes under influence of evaporation and infiltration into the soil and cropping may start when the outside water level is still high. This was a response to the high and prolonged flooding in the years 1974–1978, when molapo cropping was largely impossible. In more recent years, however, inadequate floods appeared to present an equally severe constraint to satisfactory crop production. It was therefore decided to focus also on improved, more stable crop production under fully rain-dependent conditions.
The hydrograph figure shows that crop production has not been possible in 60% of the hitherto recorded years because of the prolonged high floods. The figure also shows how flood-control measures can bring about a timely recession of the water level in the molapo. After the flood has been permitted to enter the bunded molapo, the sluice gates are closed. Recession of the water in the bunded molapo then begins under the influence of evaporation and infiltration, and allows a timely planting of the crop (in October or November). The crops use the residual soil moisture (about 100 mm) till the onset of the rainy season at the end of November or the beginning of December. Thus the growing season is prolonged, the moisture availability is increased, and crop production is enhanced. However, the success of the flood-control measures on the crop performance still depends to a great extent on the amount and distribution of the rainfall.
References
Land management
Hydrology
Irrigation
Hydraulic engineering | Water use in alluvial fans | [
"Physics",
"Chemistry",
"Engineering",
"Environmental_science"
] | 3,919 | [
"Hydrology",
"Physical systems",
"Hydraulics",
"Civil engineering",
"Environmental engineering",
"Hydraulic engineering"
] |
67,522,507 | https://en.wikipedia.org/wiki/Deltaic%20lobe | A deltaic lobe is a wetland formation that forms as a river empties water and sediment into other bodies of water. As the sediment builds up from this delta, the river will break away from its single channel and the mouth will be pushed outwards, forming a deltaic lobe.
When the rate of water discharge and lobe progradation are sufficiently high, a river can form a deltaic lobe. A single deltaic lobe includes a network of shallow channels called distributaries that make up a distributary network that branches off from the mainstream of the river. These networks can be the blueprint for a future progradational deltaic lobe when the initial deltaic lobe is abandoned. As the deltaic lobe progresses, heavier and coarser sediments settle first. As heavier sediments are deposited at the top of the deltaic lobe, smaller and finer sediments get deposited out, creating the beginning of a deltaic fan. When the alluvium, the smallest sediment carried by the deltaic lobe, is deposited and new land is formed, the resulting formation is considered a delta.
Lobes are important in forming river deltas over time by amalgamation of channel avulsions. When a lobe is prograded the frequency of avulsion decreases, and the avulsion length increases relative to a non-progradational deltaic lobe. As the deltaic lobe progrades, the channel bed gradient is lowered, resulting in a sedimentary push upstream. This shifts the location of the avulsion forwards creating a completed deltaic lobe on which overlies a delta. Lobe formation is determined by a relationship between water discharge and lobe progradation. A model must take into account both factors in order to accurately predict avulsion timing and location.
Types
Wave-dominated deltaic lobes
In wave-dominated settings the number of created deltaic lobes is limited by the number of distributaries. Lobes are rarely distinguished from one another in high tide settings as tidal currents favor channel stability and suppress avulsions. The Nile, for example, is considered to be an arcuate delta because of its arc shaping. As it is waves that shape it into an arc, it also falls under the category of a wave-dominated delta.
The word delta is derived from the Greek letter delta, which, like arcuate deltas, is roughly triangular.
Tide-dominated deltaic lobes
Tide dominated deltaic lobes are defined by high levels of sediment transfer, low numbers of distributaries, and the possible creation of tidal dominated fluvial structures such as sandbars. This high level of sediment transfer can be attributed to the tidally generated water movements that control the levels of water flux on the system, and to a lesser extent the increase of river discharge and local precipitation. All created channels are widened by the incoming and outgoing tide but the water depth does not increase significantly so the tidal deltaic lobe progrades further sea-word creating multiple distributaries and a flooding effect.
One example of a tide-dominated deltaic lobe system is the Han River delta in Korea. The Han River delta is shaped by its tidal changes in the summer and winter as well as its shallow and steep basins.
Bird's-foot deltaic lobes
The Mississippi River delta (see lede image) is made up of six subdeltas, which in turn are made up of 16 individual lobes. Individual lobes in multilobe deltas can be vastly different from one another. Lobes are sequentially abandoned; the overly-extended seaward lobe silts up, and the river finds another outlet that is shorter and more direct. This sequential channel abandonment causes the deltaic plain to grow, creating a bird's foot delta composed of many deltaic lobes.
Each major deltaic lobe is composed of complex non-detrital sediments indigenous to the basin of deposition. A change in sediment supply is responsible not only for the abandonment of a deltaic lobe, but also the coastal retreat and reaccumulation of sediments over the detrital lens.
Cuspate deltaic lobes
A cuspate deltaic lobe involves the creation and subsequent abandonment of deltaic lobe cusps to create unique linear delta formations. The cuspate deltaic lobe is defined by its abrupt rate of discharge from river to body of water, and the creation of multiple cusp systems built up into separate but active distributaries.
One such example of a cuspate delta is the Tiber River delta of Italy. The river was formed first as a deltaic lobe cusp prograded from the river mouth. An abrupt southward migration of the river mouth left the first cusp abandoned and a new deltaic lobe prograded. Finally, the two distributary channels formed one deltaic formation running through the city center.
Gilbert deltaic lobes
Gilbert deltaic lobes are defined by their movement of coarse-grained materials, relatively large sizes, and steep slopes into basins. This rise in level commonly results in intensified aggradation and eventual decrease in topset slope. The most well documented example of gilbert deltaic lobes is at the gilbert delta of Lake Bonneville.
References
Wetlands
Environmental terminology
Bodies of water | Deltaic lobe | [
"Environmental_science"
] | 1,059 | [
"Hydrology",
"Wetlands"
] |
67,522,711 | https://en.wikipedia.org/wiki/EUwarn | EUwarn (proper spelling: EUWARN) – also KATWARN international – is an internal warning system used by the European Commission in Brussels and Luxembourg, as well as the Austrian Federal Ministry of the Interior to disseminate internal warning messages within the organisation via smartphone app in dangerous situations (e.g., major fires, power outages, terrorist attacks, or pandemics).
The system is technically based on the KATWARN warning system, which has been in use in Germany since 2011, and is networked through roaming technology.
Functionality
Receiving alerts (multi-channel technology)
In order to disseminate warnings to internal and external target groups, EUwarn uses digitally networked communication channels (EUwarn app, on-board computers, smarthome, wearables, displays, portals, etc.) – so-called "multi-channel." The EUwarn system is a multi-channel system. The system is based on the European warning and information system according to Article 110 EU Directive (EU) 2018/1972.
In addition, the system can be used to communicate via different channels in order to best reach target groups (local and area warnings, group and authority warnings, topic and info channels).
Since EUwarn is based on Katwarn technology, which is widely used in Germany, and is roaming-enabled, the Katwarn app can also be used to receive EUwarn alerts.
Issuing Warnings (multi-hazard technology)
Through the use of international standards (e.g. CAP - common alerting protocol) and a secure editorial and administration platform, control centers and security centers as well as external information systems (e.g. for severe weather, floods, earthquakes, "predictive policing") can be connected to the system – so-called "multi-hazard".
Warnings and warning channels can be created and sent via the editorial and administration platform, and comprehensive administrative actions can be carried out (language selection, event and area configurations, etc.).
Multilingualism
EUwarn is multi-language capable, i.e. depending on the system settings of the smartphone, the app displays warnings in the respective language or – as default – in English. Templates for different languages can be prepared and, if necessary, automatically activated.
Technology
Developed by of the Fraunhofer Society, EUwarn is subject to constant further development in exchange with authorities, security organizations and industry. In doing so, the principles of "privacy by design" and "privacy by default" as well as the requirements of the General Data Protection Regulation (GDPR) are followed consistently.
The EUwarn system, like the Katwarn system, is based on a microservice infrastructure. This exists decentralized on several servers and thus allows for a fast and reliable distribution of warnings.
Warnings are primarily distributed via the smartphone-app, but email and SMS can be used as additional warning channels.
Tsunami drill
The European Commission's evaluation of a tsunami drill on the island of Kos shows that Katwarn-international is crucial for quickly warning those affected. During the 2019 drill, Katwarn-international was the only warning app used, along with other warning channels such as sirens, scoreboards and loudspeakers.
On November 21, 2019, the European Commission's Joint Research Centre (JRC) tested technology and procedures from the EU Tsunami Last Mile project. During the drill, EUwarn (or Katwarn-international) was used to send a tsunami warning to the participants and give them instructions on how to evacuate. The evaluation showed that a complete dissemination of the warning message was only possible by using Katwarn. For example, since sirens could not be heard in classrooms, the only way to reach a school class was through the Katwarn app on a teacher's smartphone.
References
Warning systems | EUwarn | [
"Technology",
"Engineering"
] | 793 | [
"Warning systems",
"Safety engineering",
"Measuring instruments"
] |
67,522,937 | https://en.wikipedia.org/wiki/Gjitonia | The gjitonia is a form of consolidated social cooperation and today little present in the whole historical Arbëreshë region.
It differs from the typical Italian "rione" for its urban architecture and social contribution.
Etymology
The word gjitonìa is a complex word that contains social values of parental extraction of the ancient extended family Arbëreshë; literally from Albanian gjitonìa, gjit / ngjit or 'neighborhood' or 'the neighbor', in detail the medieval Albanian word, it is used by arvaniti, or those Albanian populations established secularly in present-day Greece, while it is less widespread, or in other cases disappeared, in Albania (or 'place of the five senses', gjitonë is "literally the opposite of the indigenous neighborhood") [without source]. The origins of gjitonia in the countries of southern Italy are linked to three fundamental elements of a material type: the fence that delimits the space shared by the family, the state, or the house, meeting place and material refuge and the botanical garden, the place of Pharmacy. A journey to the places of the historical region.
Gjitonië comes from the union of the words gjindë tonë ('people of the same linguistic tonality') (or in another version it would derive from gjithë tonë 'all ours'), and is made up of two words: Gji indicating 'the people' and tonië meaning 'people who are able to make the tones of the five senses vibrate in their lived environments and confirm their belonging through the idiomatic metric'.
Architectural-urban aspect
Unlike the districts, the "gjitonie" are small agglomerations of houses often attached to each other (often understood as the smallest portion of the urban fabric) (however, as it represents a historically complex social phenomenon and as it represents a Mediterranean model, this definition does not find all enthusiasts and scholars unanimous) [without source]. The peculiarity is in the constitution of small houses that are usually built in a semicircle, flanking a "mother" house called "stately home" and all overlook a small square or open space. The gjitonia unlike the neighborhood that unites people in the sense of built, represents a social model that crosses what could be found in the indigenous neighborhood. The social structure is foreign to the typical architecture of Italian centers. The various "gjitonie" are connected to each other by small and narrow alleys, so much so that it is difficult to access them by car and in recent times this has penalized the historic centers favoring large residential complexes.
The "gjitonie" represents for the Arbereshe, Arberi or Arbanon the place of the root of the original extended family stock, it originated in the aftermath of the growth of the group that did not exceed but twenty elements, reached this name it expired and was repeated each time the generated groups reached the partition number. for this the phenomenon continually generated the search for the original stock and in order to become part of it, it was necessary to provide a series of elements of historical memory that could guarantee the originality of the dynasty. for this reason the gjitonia is the indefinite place within which the sounds and the proximity of a scattered identity are perceived and which meets to share moments and difficulties that life has in store for us
In the case of Lungro, the "gjitonie" and the urban center were the focus of a historical-urbanistic study.
Social aspect
The social aspect of " gjitonia " mainly refers to an ancient and historical experience where at the basis of human relationships coexisted values of hospitality and solidarity between the families of the neighborhood and where the aggregation was lived without difference of social classes . Mainly for the Italian-Albanian communities the " gjitonia " is a world where relationships were so strong as to create real family relationships, so much so that the phrase in Arbëresh is typical. Gjitoni gjirì "(" vinato parentato ").
Perhaps handed down by the Albanians of origin, the gjitonia is close to the values of kanùn ("Family, Individual and Hospitality") albeit contaminated and altered by customs over the years and local customs. The gjitonia has therefore become a place of socialization and contagion of knowledge and anecdotes or where one was preparing to learn a "profession" as a beginner, but it is also still a place where sacred and profane are intertwined, or, where religious songs alternate with fairy tales and popular songs.
Typically the " gjitonie " are also the place where votive bonfires for the saints are lit or where stops for religious processions are set up; these events are treated with the participation of the whole neighborhood as a unit.
The use of the "half-door", the sharing of basic necessities, the participation of the whole gjitonia in mourning and joys are some of the most visible social aspects of this phenomenon that has been diminishing over the years with depopulation of the communities Arbëreshë. In Lungro, for example, to make the meaning of " gjitonia " more marked, the neighborhood used to (and in some cases still today) get together for a mate (an Argentinian drink imported from Lungresi emigrants).
Modern times
In recent years, for various causes such as depopulation and demographic decline in the first place, instability hydrogeological, unappealing houses, architectural barriers, historic centers not accessible by cars and other reasons, this phenomenon has is slowly fading; this "light" is kept by the elderly who continue with their daily rites to keep alive the traditional gjitonia arbëreshe.
In the village of San Basile (CS) since 2010 the " A house in San Basile " initiative has been active by the municipal administration, or the sale of houses in the historic center at reasonable prices to encourage repopulation, the tourist vocation of the place and "stop" the loss of " gjitonie ".
See also
Rione
References
Bibliography
Mattanò Vincenzo Maria, 2012, Il centro antico di Lungro. Un raro documento di rigore tipologico e di sofisticata strategia insediativa, Il Coscile.
Rennis Giovan Battista, 2000, La tradizione popolare della comunità arbëreshe di Lungro'', Il Coscile.
Neighbourhoods in Italy
Urban planning
Arbëreshë culture | Gjitonia | [
"Engineering"
] | 1,350 | [
"Urban planning",
"Architecture"
] |
67,523,190 | https://en.wikipedia.org/wiki/Qalculate%21 | Qalculate! is an arbitrary precision cross-platform software calculator. It supports complex mathematical operations and concepts such as derivation, integration, data plotting, and unit conversion. It is a free and open-source software released under GPL v2.
Features
Qalculate! supports common mathematical functions and operations, multiple bases, autocompletion, complex numbers, infinite numbers, arrays and matrices, variables, mathematical and physical constants, user-defined functions, symbolic derivation and integration, solving of equations involving unknowns, uncertainty propagation using interval arithmetic, plotting using Gnuplot, unit and currency conversion and dimensional analysis, and provides a periodic table of elements, as well as several functions for computer science, such as character encoding and bitwise operations.
It provides four interfaces: two GUIs, one using GTK (qalculate-gtk) and another using Qt (qalculate-qt), a library for use in other programs (libqalculate), and a CLI program for use in a terminal (qalc).
Qalculate! (GTK+ GUI): qalculate-gtk
Qalculate! (Qt GUI): qalculate-qt
Qalculate! (CLI): qalc (usually provided by the libqalculate package)
Qalculate! (Library): libqalculate
Use in academic research
Bartel, Alexandre. "DOS Software Security: Is there Anyone Left to Patch a 25-year old Vulnerability?."
"In our example of Figure 7, we choose to execute /usr/bin/qalculate-gtk, a calculator. Since the stack of the DOSBox process is non-executable, we cannot directly inject our shellcode on it."
"The Gnome calculator was used to perform these calculations and the results were verified using the Qalculate! calculator and WolframAlpha (15) since spreadsheets are unable to perform these calculations."
See also
Mathematical software
List of arbitrary-precision arithmetic software
Comparison of software calculators
References
External links
Qalculate! - the ultimate desktop calculator at GitHub
Qalculate! - downloads at GitHub
Qalculate/qalculate-gtk GUI at GitHub
Qalculate! Manual at GitHub
QALC man page at GitHub
Ubuntu – Details of package qalculate in bionic
Ubuntu – Details of package qalculate in focal
Qalculate! code review by PVS-Studio
Free educational software
GNOME Applications
Software calculators
Free software programmed in C++
Software using the GNU General Public License | Qalculate! | [
"Mathematics"
] | 582 | [
"Software calculators",
"Mathematical software"
] |
67,523,196 | https://en.wikipedia.org/wiki/List%20of%20green%20seaweeds%20of%20the%20Cape%20Peninsula%20and%20False%20Bay | This is a list of green seaweeds recorded from the oceans bordering the Cape Peninsula in South Africa from Melkbosstrand on the West Coast to Cape Hangklip on the South Coast. This list comprises locally used common names, scientific names with author citation and recorded ranges. Ranges specified may not be the entire known range for the species, but should include the known range within the waters surrounding the Republic of South Africa.
Green seaweed refers to thousands of species of macroscopic, multicellular, marine algae in the taxon Chlorophyta
The marine ecology is unusually varied for an area of this size, as a result of the meeting of two major oceanic water masses near Cape Point, and the area extends into two coastal marine bioregions. The ecology of the west or "Atlantic Seaboard" side of the Cape Peninsula is noticeably different in character and biodiversity to that of the east, or "False Bay" side. Both sides are classified as temperate waters, but there is a significant difference in average temperature, with the Atlantic side being noticeably colder on average.
List ordering and taxonomy complies where possible with the current usage in Algaebase, and may differ from the cited source, as listed citations are primarily for range or existence of records for the region. Sub-taxa within any given taxon are arranged alphabetically as a general rule. Details of each species may be available through the relevant internal links. Synonyms may be listed where useful.
Class: Bryopsidophyceae
Order: Bryopsidales
Family: Bryopsidaceae
Bryopsis africana Areschoug, 1851, (Probably along the whole of the west Cape coast)
Bryopsis eckloniae Stegenga, Bolton & Anderson 1997, (Muizenberg, endemic)
Bryopsis hypnoides Lamouroux, 1809c, (False Bay)
Sea moss, Bryopsis myosuroides Kützing, 1856, (TMNPMPA).
Bryopsis plumosa (Hudson 1778) C.Agardh 1823,l syn. Ulva plumosa Hudson 1778, (False Bay and eastward)
Family: Caulerpaceae
Caulerpa bartoniae G. Murray, 1896, (Rare in Western Cape, Cape Hangklip and Muizenberg. Mainly from south coast. endemic)
Strap caulerpa Caulerpa filiformis (Suhr) Hering 1841, syn.Amphibolis filiformis Suhr 1834, Himandactylius filiformis (Suhr) Trevisan 1849, (False Bay to northern KwaZulu-Natal)
Feathery caulerpa Caulerpa holmesiana G. Murray, 1891, (Mainly a south coast species. the westernmost records at Cape of Good Hope, endemic)
Family: Codiaceae
Duthie's upright codium Codium duthieae Silva in Silva & Womersley, 1956, (Mainly a south and east coast species, westwards as far as Langebaan lagoon.)(From Namibia along the entire South African coast)
Fragile upright codium Codium fragile subsp. fragile (Suringar) Hariot 1889, syn Codium fragile (Suringar) Hariot subsp. capense Silva 1959a, Acanthocodium fragile Suringar 1867, (Whole of Cape west coast and most of Namibia, Eastward as far as Robberg, Plettenberg Bay)
Codium isaacii Silva, 1959a, (Namibia to Cape Peninsula, endemic)
Lucas' codium Codium lucasii Setchell subsp. capense Silva 1959a, (Strand, False Bay to southern Mozambique)
Codium papenfussii Silva, 1959a, (West coast of Cape Peninsula to southern KwaZulu-Natal, single specimen from Sodwana Bay, endemic)
Flat-lobed codium Codium platylobium Areschoug 1854, (False Bay to mouth of Mtwalume river in KwaZulu-Natal)
Stephens' codium Codium stephensiae Dickinson 1932, (St Helena Bay to Transkei, endemic)
Family: Derbesiaceae
Derbesia hollenbergii Taylor 1945, (Muizenberg and Strandfontein, False Bay, and Eastern Cape and Transkei)
Derbesia marina (Lyngbye) Solier 1846, syn. Vaucheria marina Lyngbye 1819, (Muizenberg, False Bay, and Eastern Cape and Transkei)
Family: Udoteaceae
Chlorodesmis sp. indet (Oudekraal, Cape Peninsula, endemic)
Class: Chlorophyceae
Order: Chaetophorales
Family: Chaetophoraceae
Acrochaete sp. indet (Glencairn (False Bay) and De Hoop Nature Reserve)
Family: Chroolepidaceae
Sporocladopsis novae-zelandiae Chapman, 1949 (Yzerfonten to East London)
Class: Charophyceae
Order: Charales
Family: Characeae
Foxtail stonewart, Lamprothamnium papulosum (K.Wallroth) J.Groves, 1916 (TMNPMPA)
Class: Ulvophyceae
Order: Cladophorales
Family: Cladophoraceae
Chaetomorpha aerea (Dillwyn) Kützing 1849, syn. Conferva aerea Dillwyn 1806, Chloronitum aerea (Dillwyn) Gaillon 1828, (False Bay to Cape Agulhas)
Hair weed Chaetomorpha linum (O.F.Müller) Kützing 1845, syn. Conferva linum O.F.Müller 1778, Lychaete linum (O.F.Müller) Areschoug 1851, (Kalk Bay and Simon's Town harbours)
Robust hair-weed Chaetomorpha robusta (Areschoug) Papenfuss 1940, syn. Lychaete robusta Areschoug 1851, (Namibia to Hermanus)
Chaetomorpha sp. indet, (Clovelly, False Bay)
Cape cladophora Cladophora capensis (C.Agardh) De Toni 1889, syn. Conferva capensis C.Agardh 1824, (Namibia to southern Cape Peninsula)
Turf cladophora Cladophora contexta Levring 1938, (Olifantsbos to Lüderitz)
Cladophora dalmatica Kuetzing 1843, (Glencairn, False Bay)
Blue whip cladophora Cladophora flagelliformis (Suhr) Kützing 1849, syn. Conferva flagelliformis Suhr 1840, Lychaete flagelliformis (Suhr) Areschoug 1851, (Brandfontein to Namibia)
Cladophora isaacii Simons 1960, (Port Nolloth to Cape Hangklip)
Cladophora mirabilis (C.Agardh) Rabenhorst in Hohenacker 1852, syn. Conferva mirabilis C.Agardh 1820, (Cape Hangklip to Cape Fria, Namibia)
Cladophora radiosa (Suhr) Kützing 1889, syn. Conferva radiosa Suhr 1834, (Table Bay eastwards to Cape Morgan)
Cladophora sericia (Hudson) Kützing 1843, syn. Conferva sericea Hudson 1762, Chloronitum sericeum (Hudson) Gallion 1928, (Cape Peninsula north to Melkbosstrand, east to De Hoop nature reserve)
Cladophora sp. indet. (Clovelly to Buffels Bay, Cape Peninsula)
Rhizoclonium implexum (Dillwyn) Kützing 1845, SYN. Conferva implexa Dillwyn 1809, Rhizoclonium riparium var. implexum (Dillwyn) Rosenvinge 1893, (Kraalbaai, Langebaan lagoon and Clovelly, Cape Peninsula)
Order: Ulotrichales
Family: Ulotrichaceae
Ulothrix flacca (Dillwyn) Thuret in Le Jolis 1863, syn. Conferva flacca Dillwyn 1805, Lyngbya flacca (Dillwyn) Harvey 1849, (Cape Peninsula and False Bay)
Ulothrix speciosa (Carmichael) Kützing 1849, syn Ulothrix zonata var. speciosa (Carmichael) Stockmayer, Lyngbya speciosa Carmichael 1833, Hormotrichum speciosum (Carmichael) P.L.Crouan & H.M.Crouan 1852, Urospora speciosa (Carmichael) Leblond ex G.Hamel 1931, (Known from a single collection at Kalk Bay)
Order: Ulvales
Family: Ulvaceae
Blidingia minima (Nägeli ex Kützing) Kylin 1947, syn. Enteromorpha minima Nägeli ex Kützing 1849, Enteromorpha compressa var. minima (Nägeli ex Hauck) Hamel 1931, Enteromorpha nana var. minima (Nägeli ex Hauck) Sjøstedt 1939, (Kraalbaai, Langebaan lagoon to False Bay, and Eastern Cape)
Chloropelta caespitosa Tanner 1980, (Kalk Bay and Cape Hangklip)
Enteromorpha atroviridis (Levring) M.J.Wynne 1986, syn. Ulva atroviridis Levring 1938, (Namibia to Oudekraal, Cape Peninsula)
Percursaria percursa (C.Agardh) Rosenvinge 1893, syn. Zignoa percursa (C.Agardh) Trevisan, Conferva percursa C.Agardh 1817, Enteromorpha percursa (C.Agardh) J.Agardh 1842, (Cape Peninsula – Glencairn, Scarborough, Mouille Point)
Tangleweed, Ulva clathrata (Roth) C.Agardh, 1811, (TMNPMPA),
Ulva flexuosa Wulfen 1803, syn. Enteromorpha flexuosa (Wulfen) J.Agardh 1883, (Muizenberg and Dalebrook, False Bay and Eastern Cape)
Green sea intestines, Ulva intestinalis Linnaeus 1753, syn. Conferva intestinalis (Linnaeus) Roth 1797, Tetraspora intestinalis (Linnaeus) Desvaux 1818, Scytosiphon intestinalis (Linnaeus) Lyngbye 1819, Enteromorpha intestinalis (Linnaeus) Nees 1820, Fistularia intestinalis (Linnaeus) Greville 1824, Solenia intestinalis (Linnaeus) C.Agardh 1824, Ilea intestinalis (Linnaeus) Leiblein 1827, Hydrosolen intestinalis (Linnaeus) Martius 1833, Ulva enteromorpha var. intestinalis (Linnaeus) Le Jolis 1863, Ulva bulbosa var. intestinalis (Linnaeus) Hariot 1889, Enteromorpha compressa var. intestinalis (Linnaeus) Hamel 1931, (Widespread on west and south coasts, along entire South African coast)
Ulva lactuca Linnaeus 1753, syn. Phyllona lactuca (Linnaeus) F.H.Wiggers 1780, Ulva fasciata Delile 1813, (Saldanha Bay, False Bay eastwards into Mozambique)
Ulva linza Linnaeus 1753, syn. Solenia linza (Linnaeus) C.Agardh 1824, Enteronia linza (Linnaeus) Chevallier 1836, Phycoseris linza (Linnaeus) Kützing 1843, Enteromorpha linza (Linnaeus) J.Agardh 1883, (Namibia to False Bay)
Ulva prolifera O.F.Müller 1778, syn. Ulva enteromorpha f. prolifera (O.F.Müller) Van Heurck, Ulva compressa var. prolifera (O.F.Müller) C.Agardh 1823, Enteromorpha compressa var. prolifera (O.F.Müller) Greville 1830, Enteromorpha prolifera (O.F.Müller) J.Agardh 1883, (Namibia to Eastern Cape)
Ulva rhacodes (Holmes) Papenfuss 1960, syn. Enteromorpha rhacodes Holmes 1894, (False Bay to Eastern Cape)
Rigid sea lettuce Ulva rigida C.Agardh 1823, syn. Phycoseris rigida (C.Agardh) Kützing 1843, Ulva lactuca var. rigida (C.Agardh) Le Jolis 1863, (Cape Peninsula to tropical East Africa)
Ulva uncialis (Kützing) Montagne 1850, syn. Phycoseris uncialis Kützing 1849, Ulva capensis Areschoug 1851, (Namibia to Cape Agulhas)
Geographical position of places mentioned in species ranges
Algoa Bay, Eastern Cape,
Aliwal shoal, KwaZulu-Natal,
Arniston (Waenhuiskrans), Western Cape,
Betty's Bay, Western Cape,
Bhanga Neck, KwaZulu-Natal,
Bird Island, Eastern Cape,
Blaauwberg, Western Cape,
Black Rock, Northern KwaZulu-Natal,
Brandfontein, Western Cape,
Buffelsbaai (Cape Peninsula), Western Cape,
Buffelsbaai (west coast), Western Cape,
Buffelsbaai (south coast), Western Cape,
Cape Agulhas, Western Cape,
Cape Columbine, Western Cape,
Cape Frio, Namibia,
Cape of Good Hope, Western Cape, (sometimes used historically to refer to the Cape Province, or South Africa)
Cape Peninsula, Western Cape
Cape Hangklip, Western Cape,
Cape Infanta, Western Cape,
Clovelly, False Bay, Western Cape,
Dalebrook, False Bay, Western Cape,
Danger Point, Western Cape,
De Hoop, Western Cape, (just west of Cape Infanta)
De Walle, (Die Walle), (Just west of Agulhas)
Die Dam (Quoin Point), Western Cape,
Doring Bay (Doringbaai), Western Cape,
Durban, KwaZulu-Natal,
Dwesa, Eastern Cape,
East London, Eastern Cape,
False Bay, Western Cape,
Glencairn, False Bay, Western Cape,
Groenrivier (Groen River),
Groot Bergrivier estuary (Berg River, Velddrif), Western Cape,
Haga Haga, Eastern Cape (N of E.London)
The Haven, Eastern Cape, 150 km west of Port St. Johns,
Hermanus, Western Cape,
Hluleka, Eastern Cape,
Hondeklipbaai, Northern Cape,
Hout Bay, Cape Peninsula, Western Cape,
Isipingo, KwaZulu-Natal,
Island Rock, KwaZulu-Natal,
Kalk Bay, False Bay, Western Cape,
Kei River, Eastern Cape,
Kenton-on-Sea, Eastern Cape,
Keurboomstrand, Plettenberg Bay, Western Cape,
Knysna, Western Cape,
Kommetjie, Western Cape,
Koppie Alleen, De Hoop, Western Cape,
Kosi Bay, Kwa-Zulu-Natal,
Kowie River, Eastern Cape,
Kraalbaai, Langebaan lagoon, Western Cape,
Lala Nek, KwaZulu-Natal,
Lamberts Bay, Western Cape,
Leadsman shoal, KwaZulu-Natal,
Langebaan Lagoon, Western Cape,
Llandudno, Cape Peninsula, Western Cape,
Lüderitz, Namibia,
Mabibi, Kwa-Zulu-Natal,
Mapelane, Maphelana, KwaZulu-Natal, near St. Lucia,
Melkbosstrand, Western Cape,
Mission Rocks, KwaZulu-Natal,
Mkambati, KwaZulu-Natal,
Morgan's Bay, Eastern Cape, (Near Kei mouth)
Möwe Bay, Namibia, (Möwe Point lighthouse)
Mtwalume river, KwaZulu-Natal,
Noordhoek, Cape Peninsula, Western Cape,
Muizenberg, False Bay, Western Cape,
Oatlands Point, False Bay, Western Cape,
Oudekraal, Cape Peninsula, Western Cape,
Olifantsbos, Cape Peninsula, Western Cape,
Palm Beach, South Africa,
Park Rynie, KwaZulu-Natal,
Paternoster, Western Cape,
Papenkuilsfontein, Western Cape, 10 km west of Agulhas
Pearly Beach, Western Cape,
Platbank, Cape Peninsula, Western Cape, °'"S °'E
Platboombaai,
Plettenberg Bay, Western Cape,
Ponta do Ouro, Mozambique border,
Port Alfred, Eastern Cape,
Port Edward, KwaZulu-Natal
Port Elizabeth, Eastern Cape,
Port Nolloth, Northern Cape,
Port St. Johns, KwaZulu-Natal,
Postberg, Western Cape,
Protea Banks, KwaZulu-Natal,
Rabbit Rock, KwaZulu-Natal,
Robberg, Western Cape,
Rocky Point, Namibia,
Saldanha Bay, Western Cape,
Saxon Reef, KwaZulu-Natal, (near Mozambique border),
Scarborough, Cape Peninsula, Western Cape,
Scottburgh, KwaZulu-Natal,
Sea Point, Cape Peninsula, Western Cape,
Shelly Beach, KwaZulu-Natal, KwaZulu-Natal,
Simon's Town, Western Cape,
Smitswinkel Bay, False Bay, Western Cape,
Sodwana Bay, KwaZulu-Natal,
Soetwater,
Stilbaai (Still Bay), Western Cape, E
St Helena Bay, Western Cape,
St. James, False Bay, Western Cape,
St Lucia, KwaZulu-Natal,
Strand, Western Cape,
Strandfontein, False Bay, Western Cape,
Strandfontein, Western Cape,
Swakopmund, Namibia,
Swartklip, False Bay, Western Cape,
Swartkops River,
Table Bay, Western Cape,
Three Anchor Bay, Cape Peninsula, Western Cape,
Three Sisters (Eastern Cape), Riet River, 10 km west of Port Alfred, Eastern Cape,
Trafalgar, KwaZulu-Natal,
Tsitsikamma, Eastern Cape,
Umhlali, KwaZulu-Natal, (mHlali river mouth)
Umpangazi, KwaZulu-Natal, (Cape Vidal?)
Uvongo, KwaZulu-Natal,
Waterloo Bay, Eastern Cape,
Yzerfontein, Western Cape,
See also
References
South Africa
Biology-related lists
Lists of biota of South Africa
Marine biota of South Africa | List of green seaweeds of the Cape Peninsula and False Bay | [
"Biology"
] | 3,943 | [
"Seaweeds",
"Algae"
] |
67,523,275 | https://en.wikipedia.org/wiki/List%20of%20brown%20seaweeds%20of%20the%20Cape%20Peninsula%20and%20False%20Bay | This is a list of brown seaweeds recorded from the oceans bordering The Cape Peninsula in South Africa from Melkbosstrand on the West Coast to Cape Hangklip on the South Coast.
This list comprises locally used common names, scientific names with author citation and recorded ranges. Ranges specified may not be the entire known range for the species, but should include the known range within the waters surrounding the Republic of South Africa.
Brown seaweed refers to thousands of species of macroscopic, multicellular, marine algae in the taxon Phaeophyta
The marine ecology is unusually varied for an area of this size, as a result of the meeting of two major oceanic water masses near Cape Point, and the park extends into two coastal marine bioregions. The ecology of the west or "Atlantic Seaboard" side of the Cape Peninsula is noticeably different in character and biodiversity to that of the east, or "False Bay" side. Both sides are classified as temperate waters, but there is a significant difference in average temperature, with the Atlantic side being noticeably colder on average.
List ordering and taxonomy complies where possible with the current usage in Algaebase, and may differ from the cited source, as listed citations are primarily for range or existence of records for the region.
Sub-taxa within any given taxon are arranged alphabetically as a general rule.
Details of each species may be available through the relevant internal links. Synonyms may be listed where useful.
Class: Phaeophyceae
Order: Cutleriales
Family Cutleriaceae
Aglaozonia sp. (Muizenberg, False Bay. Brandfontein. Bird Island, eastern Cape)
Order: Desmarestiales
Family Desmarestiaceae
Acid weed Desmarestia herbacea subsp. firma (C.Agardh) A.F.Peters, E.C.Yang, F.C.Küpper & Prud'Homme van Reine, 2014, recorded as syn. Desmarestia firma (C.Agardh) Skottsberg in Nordenskjöld 1907, syn. Sporochnus herbaceus var. firma C.Agardh 1824, (Möwe Bay, Namibia to Betty's Bay. Doubtful record for Cape Agulhas)
Order: Dictyotales
Family Dictyotaceae
Dictyota dichotoma (Hudson) J.V.Lamouroux 1809, syn. Ulva dichotoma Hudson 1762, Zonaria dichotoma (Hudson) C.Agardh 1817, Fucus dichotomus (Hudson) Bertolini 1819, Haliseris dichotoma (Hudson) Sprengel 1827, Dichophyllium dichotomum (Hudson) Kützing 1843,(Langebaan and False Bay to Natal. D. dichotoma var. intricata (C.Agardh) Greville 1830, common at Kalk Bay and Dalebrook, and occurring more or less throughout the range of the species)
Dictyota liturata J.Agardh 1848, (Kommetjie on Cape Peninsula to Umhlali in KwaZulu-Natal)
Spotted dictyota Dictyota naevosa (Suhr) Montagne 1840, syn. Zonaria naevosa Suhr 1834, Cutleria naevosa (Suhr) Hering ex Krauss 1846, (Die Walle to Umhlali, KwaZulu-Natal)(Cape Peninsula eastward into KwaZulu-Natal as far as Mission Rocks)
Intricate dictyota, Dictyota spp.
Multi-fanned zonaria Exallosorus harveyanus (Pappe ex Kützing) J.A.Phillips, 1997. Syn. Zonaria harveyana (Pappe ex Kützing) Areschoug 1851, (Platbank, False Bay to KwaZulu-Natal as far north as Park Rynie. Endemic)
Articulated zonaria, Zonaria subarticulata (J.V.Lamouroux) Papenfuss, 1944.
Order: Ectocarpales
Family: Acinetosporaceae
Acinetospora crinita (Carmichael) Sauvageau 1899, syn. Acinetospora pusilla var. crinita (Carmichael) Batters, Ectocarpus crinitus Carmichael 1833, (False Bay, Eastern Cape)
Feldmannia irregularis (Kützing) G.Hamel 1939, syn. Ectocarpus irregularis Kützing 1845, Giffordia irregularis (Kützing) Joly 1965, Hincksia irregularis (Kützing) Amsler 1991, (Cape Peninsula, Langebaan lagoon and Eastern Cape)
Hincksia granulosa (Smith) P.C.Silva in P.C.Silva, E.G.Meñez & R.L.Moe 1987, Conferva granulosa Smith 1811, Ectocarpus granulosus (Smith) C.Agardh 1828, Giffordia granulosa (Smith) G.Hamel 1939, (Muizenberg and Oudekraal, also Namibia)
Family Chordariaceae
Asperococcus compressus A.W.Griffiths ex W.J.Hooker 1833, (Table Bay)
Furry slime strings, Chordariaceae spp.
Brown brains Leathesia marina (Lyngbye) Decaisne 1842, syn. Chaetophora marina Lyngbye 1819, Leathesia difformis (Linnaeus) J.E. Areschoug 1847, (All South African coasts: common on west coast, internittent in eastern Cape and KwaZulu-Natal)
Myriocladia capensis J. Agardh 1848, (Port Nolloth to De Hoop Nature Reserve, endemic)
Myriogloea abbreviata Kylin 1940, (Sea Point to Port Nolloth, endemic)
Myriogloea papenfussii Kylin 1940, (False Bay to Melkbosstrand, endemic)
Myrionema cf. magnusii (Sauvageau) Loiseaux 1967, syn. Ascocyclus magnusii Sauvageau 1927, (Glencairn)
Papenfussiella gracilis Kylin 1940, (Platboombaai to Swakopmund, Namibia. Endemic to southern Africa)
Zeacarpa leiomorpha Anderson, Simons & Bolton 1988, (Yzerfontein to Dalebrook, Probably more widespread)
Family Chordariopsidaceae
Cape cord weed Chordariopsis capensis (C.Agardh) Kylin 1940, syn. Chordaria flagelliformis var. capensis C.Agardh 1824, (Cape Frio, Namibia to at least Arniston)
Family Ectocarpaceae
Ectocarpus acutus Setchell & Gardner 1922c, (Olifantsbos to Hondeklipbaai)
Ectocarpus fasciculatus Harvey 1841, (Melkbosstrand to De Hoop)
Ectocarpus siliculosus (Dillwyn) Lyngbye 1819, syn. Conferva siliculosa Dillwyn 1809, Ceramium siliculosum (Dillwyn) C.Agardh 1811, Ectocarpus confervoides f. siliculosus (Dillwyn) Kjellman 1872, Ectocarpus confervoides var. siliculosus (Dillwyn) Farlow 1881, (Port Nolloth to Eastern Cape)
Ectocarpus spp.
Family: Pylaiellaceae
Bachelotia antillarum (Grunow) Gerloff 1959, syn. Ectocarpus antillarum Grunow 1867, Pylaiella antillarum (Grunow) De Toni 1895, (False Bay to KwaZulu-Natal)
Family Scytosiphonaceae
Oyster thief Colpomenia sinuosa (Mertens ex Roth) Derbès & Solier in Castagne 1851, syn. Ulva sinuosa Mertens ex Roth 1806, Encoelium sinuosum (Mertens ex Roth) C.Agardh 1820, Stilophora sinuosa (Mertens ex Roth) C.Agardh 1827, Asperococcus sinuosus (Mertens ex Roth) Bory de Saint-Vincent 1832, Asperococcus sinuosus (C.Agardh) Zanardini 1841, Hydroclathrus sinuosus (Mertens) ex Roth) Zanardini 1843, (Throughout South Africa)
Compsonema cf. sessile Setchell & Gardner 1922a, (Oudekraal)
Starred cushion Iyengaria stellata (Børgesen) Børgesen 1939, syn. Rosenvingea stellata Børgesen 1928, Colpomenia stellata (Børgesen) Børgesen 1930, (Southern Cape Peninsula to KwaZulu-Natal)
Petalonia binghamiae (J.Agardh) K.L.Vinogradova, 1973, also recorded as syn. Endarachne binghamiae J.Agardh 1896, (False Bay eastwards to KwaZulu-Natal as far as Port Edward)
Petalonia fascia (O.F.Müller) Kuntze 1898, syn. Fucus fascia O.F.Müller 1778, Laminaria fascia (O.F.Müller) C.Agardh 1817, Ulva fascia (O.F.Müller) Lyngbye 1819, Ilea fascia (O.F.Müller) Fries 1835, Phyllitis fascia (O.F.Müller) Kützing 1843, Saccharina fascia (O.F.Müller) Kuntze 1891, (Yzerfontein to Soetwater)
Sausage skins, Scytosiphon lomentaria (Lyngbye) Link 1833, Chorda lomentaria Lyngbye 1819, Scytosiphon filum var. lomentarius (Lyngbye) C.Agardh 1820, Fucus lomentarius (Lyngbye) Sommerfelt 1826, Scytosiphon simplicissimus (Clemente) Cremades 1990, Ulva simplicissima Clemente 1807, (Simon's Town to Lüderitz)
Order: Fucales
Family Bifurcariopsidaceae
Upright wrack Bifurcariopsis capensis (Areschoug) Papenfuss 1940a, syn. Fucodium capense Areschoug 1854, (Cape Infanta to Groen River)
Family Sargassaceae
Long-leafed sargassum Anthophycus longifolius (Turner) Kützing, 1849 syn. Fucus longifolius Turner 1809, Sargassum longifolium (Turner) C.Agardh 1820, Carpophyllum longifolium (Turner) De Toni 1895, (Platboombaai eastwards as far as Uvongo in southern KwaZulu-Natal)
Constricted axils Axillariella constricta (J.Agardh) P.C.Silva 1959b, syn. Fucodium constrictum J.Agardh 1848, Ascophyllum constricta (J.Agardh) Kuntze 1891, Ascophylla constricta (Kützing) Kuntze 1891, (Cape Peninsula to Cape Columbine)
Hanging wrack Brassicophycus brassicaeformis (Kützing) Draisma, Ballesteros, F.Rousseau & T.Thibaut 2010, syn. Pycnophycus brassicaeformis Kützing 1860, Bifurcaria brassicaeformis (Kützing) E.S.Barton 1893, (Cape Agulhas to Sea Point)
Cystophora fibrosa Simons, 1970, (De Walle to Koppie Allen, and Platboom)
Sargassum elegans Suhr, 1840, (False Bay to Mozambique. Endemic to southern Africa)
Different-leafed sargassum, Sargassum incisifolium (Turner) C.Agardh 1820, syn. Fucus incisifolius Turner 1811, Sargassum heterophyllum (Turner) C.Agardh, 1820, (False Bay eastward into Mozambique. Restricted to Southern Africa and Madagascar)
Order: Laminariales
Family Laminariaceae
Split-fan kelp Laminaria pallida Greville in J. Agardh 1848, Hafgygia pallida (Greville) Areschchoug 1883, Saccharina pallida (Greville) Kuntze 1891, (Danger Point to Cape Nolloth, as the schinzii form to at least Rocky Point in northern Namibia)
Bladder kelp Macrocystis pyrifera (Linnaeus) C.Agardh, 1820, also recorded as syn. Macrocystis angustifolia Bory de Saint-Vincent 1826, (Occasional in drift in False Bay. Attached from Cape Point to Paternoster)
Family Lessoniaceae
Sea bamboo Ecklonia maxima (Osbeck) Papenfuss 1940b, syn. Fucus maximus Osbeck 1757, (Papenkuilsfontein 10 km west of Cape Agulhas to north of Lüderitz, Namibia)
Spined kelp Ecklonia radiata (C.Agardh) J.Agardh 1848, Laminaria radiata C.Agardh 1817, Capea radiata (C.Agardh) Endlicher 1843, (Forms with long stipes and rugose blades in False Bay, Spinose forms common at Die Dam, Otherwise species common from Koppie Allen to Southern Natal. Longer stiped smooth bladed form as far east as parts of Zululand)(Deep water populations extend to Sodwana Bay at depths up to 60m)
Order: Ralfsiales
Family Neoralfsiaceae
Neoralfsia expansa (J.Agardh) P.-E.Lim & H.Kawai ex Kraft 2009, syn. Myrionema expansum J.Agardh 1847, Ralfsia expansa (J.Agardh) J.Agardh 1848, (unclear distribution)
Family Ralfsiaceae
Ralfsia Ralfsia verrucosa (Areschoug) J.Agardh 1848, syn. Cruoria verrucosa Areschoug 1843, (Common on all west coast shores and probably throughout the Agulhas marine province)
Order: Scytothamnales
Family Splachnidiaceae
Dead man's fingers, Splachnidium rugosum (Linnaeus) Greville 1830, (Dominant in mid-shore throughout west coast, Lüderitz, Namibia to eastern Cape)
Order: Sphacelariales
Family Sphacelariaceae
Sphacelaria brachygonia Montagne 1843, (St. James and Strandfontein, False Bay, More frequent on south coast as far as Transkei)
Sphacelaria rigidula Kützing 1843, (Kalk Bay in False Bay to at least Transkei)
Family Stypocaulaceae
Broom-weed, Halopteris funicularis (Montagne) Sauvageau, 1904, also recorded as syn. Stypocaulon funiculare (Montagne) Kützing 1849, (Port Nolloth to Cape Agulhas and Tsitsikamma)
Order: Sporochnales
Family Sporochnaceae
Carpomitra costata (Stackhouse) Batters 1902, (Algoa Bay. Vulcan Rock, Hout Bay)
Sporochnus pedunculatus (Hudson) C. Agardh 1820, (Strandfontein)
Geographical position of places mentioned in species ranges
Algoa Bay, Eastern Cape,
Aliwal shoal, KwaZulu-Natal,
Arniston (Waenhuiskrans), Western Cape,
Betty's Bay, Western Cape,
Bhanga Neck, KwaZulu-Natal,
Bird Island, Eastern Cape,
Blaauwberg, Western Cape,
Black Rock, Northern KwaZulu-Natal,
Brandfontein, Western Cape,
Buffelsbaai (Cape Peninsula), Western Cape,
Buffelsbaai (west coast), Western Cape,
Buffelsbaai (south coast), Western Cape,
Cape Agulhas, Western Cape,
Cape Columbine, Western Cape,
Cape Frio, Namibia,
Cape of Good Hope, Western Cape, (sometimes used historically to refer to the Cape Province, or South Africa)
Cape Peninsula, Western Cape
Cape Hangklip, Western Cape,
Cape Infanta, Western Cape,
Clovelly, False Bay, Western Cape,
Dalebrook, False Bay, Western Cape,
Danger Point, Western Cape,
De Hoop, Western Cape, (just west of Cape Infanta)
De Walle, (Die Walle), (Just west of Agulhas)
Die Dam (Quoin Point), Western Cape,
Doring Bay (Doringbaai), Western Cape,
Durban, KwaZulu-Natal,
Dwesa, Eastern Cape,
East London, Eastern Cape,
False Bay, Western Cape,
Glencairn, False Bay, Western Cape,
Groenrivier (Groen River),
Groot Bergrivier estuary (Berg River, Velddrif), Western Cape,
Haga Haga, Eastern Cape (N of E.London)
The Haven, Eastern Cape, 150 km west of Port St. Johns,
Hermanus, Western Cape,
Hluleka, Eastern Cape,
Hondeklipbaai, Northern Cape,
Hout Bay, Cape Peninsula, Western Cape,
Isipingo, KwaZulu-Natal,
Island Rock, KwaZulu-Natal,
Kalk Bay, False Bay, Western Cape,
Kei River, Eastern Cape,
Kenton-on-Sea, Eastern Cape,
Keurboomstrand, Plettenberg Bay, Western Cape,
Knysna, Western Cape,
Kommetjie, Western Cape,
Koppie Alleen, De Hoop, Western Cape,
Kosi Bay, Kwa-Zulu-Natal,
Kowie River, Eastern Cape,
Kraalbaai, Langebaan lagoon, Western Cape,
Lala Nek, KwaZulu-Natal,
Lamberts Bay, Western Cape,
Leadsman shoal, KwaZulu-Natal,
Langebaan Lagoon, Western Cape,
Llandudno, Cape Peninsula, Western Cape,
Lüderitz, Namibia,
Mabibi, Kwa-Zulu-Natal,
Mapelane, Maphelana, KwaZulu-Natal, near St. Lucia,
Melkbosstrand, Western Cape,
Mission Rocks, KwaZulu-Natal,
Mkambati, KwaZulu-Natal,
Morgan's Bay, Eastern Cape, (Near Kei mouth)
Möwe Bay, Namibia, (Möwe Point lighthouse)
Mtwalume river, KwaZulu-Natal,
Noordhoek, Cape Peninsula, Western Cape,
Muizenberg, False Bay, Western Cape,
Oatlands Point, False Bay, Western Cape,
Oudekraal, Cape Peninsula, Western Cape,
Olifantsbos, Cape Peninsula, Western Cape,
Palm Beach, South Africa,
Park Rynie, KwaZulu-Natal,
Paternoster, Western Cape,
Papenkuilsfontein, Western Cape, 10 km west of Agulhas
Pearly Beach, Western Cape,
Platbank, Cape Peninsula, Western Cape, °'"S °'E
Platboombaai,
Plettenberg Bay, Western Cape,
Ponta do Ouro, Mozambique border,
Port Alfred, Eastern Cape,
Port Edward, KwaZulu-Natal
Port Elizabeth, Eastern Cape,
Port Nolloth, Northern Cape,
Port St. Johns, KwaZulu-Natal,
Postberg, Western Cape,
Protea Banks, KwaZulu-Natal,
Rabbit Rock, KwaZulu-Natal,
Robberg, Western Cape,
Rocky Point, Namibia,
Saldanha Bay, Western Cape,
Saxon Reef, KwaZulu-Natal, (near Mozambique border),
Scarborough, Cape Peninsula, Western Cape,
Scottburgh, KwaZulu-Natal,
Sea Point, Cape Peninsula, Western Cape,
Shelly Beach, KwaZulu-Natal, KwaZulu-Natal,
Simon's Town, Western Cape,
Smitswinkel Bay, False Bay, Western Cape,
Sodwana Bay, KwaZulu-Natal,
Soetwater,
Stilbaai (Still Bay), Western Cape, E
St Helena Bay, Western Cape,
St. James, False Bay, Western Cape,
St Lucia, KwaZulu-Natal,
Strand, Western Cape,
Strandfontein, False Bay, Western Cape,
Strandfontein, Western Cape,
Swakopmund, Namibia,
Swartklip, False Bay, Western Cape,
Swartkops River,
Table Bay, Western Cape,
Three Anchor Bay, Cape Peninsula, Western Cape,
Three Sisters (Eastern Cape), Riet River, 10 km west of Port Alfred, Eastern Cape,
Trafalgar, KwaZulu-Natal,
Tsitsikamma, Eastern Cape,
Umhlali, KwaZulu-Natal, (mHlali river mouth)
Umpangazi, KwaZulu-Natal, (Cape Vidal?)
Uvongo, KwaZulu-Natal,
Waterloo Bay, Eastern Cape,
Yzerfontein, Western Cape,
See also
References
South Africa
Biology-related lists
Lists of biota of South Africa
Marine biota of South Africa | List of brown seaweeds of the Cape Peninsula and False Bay | [
"Biology"
] | 4,548 | [
"Seaweeds",
"Algae"
] |
67,524,235 | https://en.wikipedia.org/wiki/Phantom%20Secure | Phantom Secure was a Canadian company that provided modified secure mobile phones, which were equipped with a remotely operated kill switch. After its shutdown, criminal users fled to alternatives including ANOM, which turned out to be a honeypot run by the FBI.
Arrest of Vincent Ramos
CEO Vincent Ramos was arrested at an Over Easy restaurant in Bellingham, Washington on 7 March 2018. At the time he lived in Richmond, British Columbia. Ramos had turned state's witness by June. Vincent Ramos did not provide login information or backdoors to Phantom Secure, deciding to instead serve the max sentence given, which was nine years in US prison.
Convictions
It was said to have provided "secure communications to high-level drug traffickers and other criminal organization leaders" according to a 2018 FBI takedown announcement. Its CEO, Vincent Ramos, was sentenced in 2019 to a nine-year prison sentence after telling undercover agents that he created the device to help drug traffickers. Customers included members of the Sinaloa Cartel, and the FBI reportedly asked Ramos to plant a backdoor in Phantom Secure's encrypted network, which he refused to do.
Cameron Ortis
In September 2019 the RCMP arrested a man charged with leaking information to foreign entities. Cameron Ortis was director general of the National Intelligence Coordination Centre, a branch of the RCMP that specialised in analytics. He had been running the NICC since 2016 having joined the RCMP in 2007 as a strategic analyst from an academic background in technology and crime, after completing a PhD at the University of British Columbia before he joined.
In 2018 a joint operation between the RCMP and FBI indicated that there might be a mole, the investigation led to the arrest of Ortis. Media reports have linked his arrest to Phantom Secure.
He faces five charges under the Security of Information Act and the Criminal Code.
Charges against him include that in 2015 he supplied "special operational information" to "V.R", believed to be Vincent Ramos. In early 2024, Ortis was sentenced to 14 years in prison.
See also
EncroChat
References
Anonymity networks
Cyberspace
Dark web | Phantom Secure | [
"Technology"
] | 430 | [
"Information technology",
"Cyberspace"
] |
67,524,251 | https://en.wikipedia.org/wiki/Aclonifen | Aclonifen is a diphenyl ether herbicide which has been used in agriculture since the 1980s. Its mode of action has been uncertain, with evidence suggesting it might interfere with carotenoid biosynthesis or inhibit the enzyme protoporphyrinogen oxidase (PPO). Both mechanisms could result in the observed whole-plant effect of bleaching (removal of leaf colour) and the compound includes chemical features (a nitro group attached to a diphenyl ether) that are known to result in PPO effects, as seen with acifluorfen, for example. In 2020, further research revealed that aclonifen has a different and novel mode of action, targeting solanesyl diphosphate synthase which would also cause bleaching.
History
The nitrophenyl ethers are a well-known class of herbicides, the oldest member of which was nitrofen, invented by Rohm & Haas and first registered for sale in 1964. This area of chemistry became very competitive, with the Mobil Oil Corporation's filing in 1969 and grant in 1974 of a patent to the structural analog with a COOCH3 group adjacent to the nitro group of nitrofen. This product, bifenox, was launched in 1981. Meanwhile, Rohm & Haas introduced acifluorfen (as its sodium salt) in 1980. It had much improved properties including a wider spectrum of herbicidal effect and good safety to soybean crops. The first patent for this material was published in December 1975,
Celamerck scientists were also working on analogs retaining the 4-nitrodiphenyl ether framework and in 1978 filed a patent of relatively narrow scope which claimed compounds having an amine group adjacent to the nitro substituent and also having an additional chlorine atom between the amine and the oxygen of the diphenyl ether. 2-Chloro-3-phenoxy-6-nitroaniline was described as having selectivity, so that important grass weeds could be controlled within dicot crops and this lack of damage to the crop extended to some cereals. Aclonifen was subsequently developed and marketed by Rhône-Poulenc under the code number RPA099795 and launched in 1983 in Europe.
Synthesis
The preparation of aclonifen first described in Celamerck patents starts from 2,3,4-trichloronitrobenzene. This is reacted in an autoclave with ammonia in dimethyl sulfoxide. The intermediate aniline is treated with potassium phenolate in an Ullmann ether synthesis using acetonitrile as solvent.
Mechanism of action
The detailed mechanism of action for nitro diphenyl ether herbicides such as acifluorfen was unknown at the time they were invented. The effects visible on whole plants are chlorosis and desiccation: in 1983 several hypotheses were advanced regarding the molecular-level interactions which might explain these symptoms. By 1992, it was becoming clear that most compounds of this class inhibit the enzyme protoporphyrinogen oxidase (PPO), which leads to an accumulation of protoporphyrin IX in the plant cells. This is a potent photosensitizer which activates oxygen, leading to lipid peroxidation. Both light and oxygen are required for this process to kill the plant.
Aclonifen was shown to be an inhibitor of PPO but in addition had effects on carotenoid synthesis, by inhibition of phytoene desaturase at similar concentrations in vitro. This led to the conclusion that it expressed a dual mode of action. In 2020, further research revealed that it is likely to have a completely different and novel mode of action, targeting solanesyl diphosphate synthase. This has led to its being classified in its own group for the purposes of resistance management.
Uses
Aclonifen is registered for use in the European Union, where a two-tiered approach is used for approval and authorisation. Before a formulated product can be developed for market, the active substance must be approved. Then authorisation for the specific product must be sought from every Member State that the applicant wants to sell it to. Afterwards, there is a monitoring programme to make sure the pesticide residues in food are below the limits set by the European Food Safety Authority. The active ingredient is registered for use against weeds in crops including cereals, potato and sunflower. It is particularly safe to sunflower, owing to the metabolism which occurs in that crop.
Aclonifen is now supplied by Bayer Crop Science under a variety of brand names according to the crop and formulation. For example, Proclus is used in winter wheat and Emerger in potatoes. It is normally applied pre-emergence (before weeds are visible in the crop) and controls or suppresses species including Alopecurus myosuroides, Anthemis cotula, Chenopodium album, Fallopia convolvulus, Galium aparine and Viola arvensis when used at application rates of 600 g a.i. per hectare.
In the UK, following the withdrawal of linuron in 2017, aclonifen began to be used as a pre-emergence herbicide in potatoes.
References
External links
Herbicides
Nitrobenzene derivatives
Anilines
Chloroarenes
Phenol ethers | Aclonifen | [
"Biology"
] | 1,122 | [
"Herbicides",
"Biocides"
] |
67,525,376 | https://en.wikipedia.org/wiki/Representative%20layer%20theory | The concept of the representative layer came about though the work of Donald Dahm, with the assistance of Kevin Dahm and Karl Norris, to describe spectroscopic properties of particulate samples, especially as applied to near-infrared spectroscopy. A representative layer has the same void fraction as the sample it represents and each particle type in the sample has the same volume fraction and surface area fraction as does the sample as a whole. The spectroscopic properties of a representative layer can be derived from the spectroscopic properties of particles, which may be determined by a wide variety of ways. While a representative layer could be used in any theory that relies on the mathematics of plane parallel layers, there is a set of definitions and mathematics, some old and some new, which have become part of representative layer theory.
Representative layer theory can be used to determine the spectroscopic properties of an assembly of particles from those of the individual particles in the assembly. The sample is modeled as a series of layers, each of which is parallel to each other and perpendicular to the incident beam. The mathematics of plane parallel layers is then used to extract the desired properties from the data, most notably that of the linear absorption coefficient which behaves in the manner of the coefficient in Beer’s law. The representative layer theory gives a way of performing the calculations for new sample properties by changing the properties of a single layer of the particles, which doesn’t require reworking the mathematics for a sample as a whole.
History
The first attempt to account for transmission and reflection of a layered material was carried out by George G. Stokes in about 1860 and led to some very useful relationships. John W. Strutt (Lord Rayleigh) and Gustav Mie developed the theory of single scatter to a high degree, but Aurthur Schuster was the first to consider multiple scatter. He was concerned with the cloudy atmospheres of stars, and developed a plane-parallel layer model in which the radiation field was divided into forward and backward components. This same model was used much later by Paul Kubelka and Franz Munk, whose names are usually attached to it by spectroscopists.
Following WWII, the field of reflectance spectroscopy was heavily researched, both theoretically and experimentally. The remission function, , following Kubelka-Munk theory, was the leading contender as the metric of absorption analogous to the absorbance function in transmission absorption spectroscopy.
The form of the K-M solution originally was: , but it was rewritten in terms of linear coefficients by some authors, becoming , taking and as being equivalent to the linear absorption and scattering coefficients as they appear in the Bouguer-Lambert law, even though sources who derived the equations preferred the symbolism and usually emphasized that and was a remission or back-scattering parameter, which for the case of diffuse scatter should properly be taken as an integral.
In 1966, in a book entitled Reflectance Spectroscopy, Harry Hecht had pointed out that the formulation led to , which enabled plotting "against the wavelength or wave-number for a particular sample" giving a curve corresponding "to the real absorption determined by transmission measurements, except for a displacement by in the ordinate direction." However, in data presented, "the marked deviation in the remission function ... in the region of large extinction is obvious." He listed various reasons given by other authors for this "failure ... to remain valid in strongly absorbing materials", including: "incomplete diffusion in the scattering process"; failure to use "diffuse illumination; "increased proportion of regular reflection"; but concluded that "notwithstanding the above mentioned difficulties, ... the remission function should be a linear function of the concentration at a given wavelength for a constant particle size" though stating that "this discussion has been restricted entirely to the reflectance of homogeneous powder layers" though "equation systems for combination of inhomogeneous layers cannot be solved for the scattering and absorbing properties even in the simple case of a dual combination of sublayers. ... This means that the (Kubelka-Munk) theory fails to include, in an explicit manner, any dependence of reflection on particle size or shape or refractive index".
The field of Near infrared spectroscopy (NIR) got its start in 1968, when Karl Norris and co-workers with the Instrumentation Research Lab of the U.S. Department of Agriculture first applied the technology to agricultural products. The USDA discovered how to use NIR empirically, based on available sources, gratings, and detector materials. Even the wavelength range of NIR was empirically set based on the operational range of a PbS detector. Consequently, it was not seen as a rigorous science: it had not evolved in the usual way, from research institutions to general usage. Even though the Kubelka-Munk theory provided a remission function that could have been used as the absorption metric, Norris selected for convenience. He believed that the problem of non-linearity between the metric and concentration was due to particle size (a theoretical concern) and stray light (an instrumental effect). In qualitative terms, he would explain differences in spectra of different particle size as changes in the effective path length that the light traveled though the sample.
In 1976, Hecht published an exhaustive evaluation of the various theories which were considered to be fairly general. In it, he presented his derivation of the Hecht finite difference formula by replacing the fundamental differential equations of the Kubelka-Munk theory by the finite difference equations, and obtained: . He noted "it is well known that a plot of versus deviates from linearity for high values of , and it appears that (this equation) can be used to explain the deviations in part", and "represents an improvement in the range of validity and shows the need to consider the particulate nature of scattering media in developing a more precise theory by which absolute absorptivities can be determined."
In 1982, Gerry Birth convened a meeting of experts in several areas that impacted NIR Spectroscopy, with emphasis on diffuse reflectance spectroscopy, no matter which portion of the electromagnetic spectrum might be used. This was the beginning of the International Diffuse Reflectance Conference. At this meeting was Harry Hecht, who may have at the time been the world's most knowledgeable person in the theory of diffuse reflectance. Gerry himself took many photographs illustrating various aspects of diffuse reflectance, many of which were not explainable with the best available theories. In 1987, Birth and Hecht wrote a joint article in a new handbook, which pointed a direction for future theoretical work.
In 1994, Donald and Kevin Dahm began using numerical techniques to calculate remission and transmission from samples of varying numbers of plane parallel layers from absorption and remission fractions for a single layer. Using this entirely independent approach, they found a function that was the independent of the number of layers of the sample. This function, called the Absorption/Remission function and nick-named the ART function, is defined as: . Besides the relationships displayed here, the formulas obtained for the general case are entirely consistent with the Stokes formulas, the equations of Benford, and Hecht's finite difference formula. For the special cases of infinitesimal or infinitely dilute particles, it gives results consistent with the Schuster equation for isotropic scattering and Kubelka–Munk equation. These equations are all for plane parallel layers using two light streams. This cumulative mathematics was tested on data collected using directed radiation on plastic sheets, a system that precisely matches the physical model of a series of plane parallel layers, and found to conform. The mathematics provided: 1) a method to use plane parallel mathematics to separate absorption and remission coefficients for a sample; 2) an Absorption/Remission function that is constant for all sample thickness; and 3) equations relating the absorption and remission of one thickness of sample to that of any other thickness.
Mathematics of plane parallel layers in absorption spectroscopy
Using simplifying assumptions, the spectroscopic parameters (absorption, remission, and transmission fractions) of a plane parallel layer can be built from the refractive index of the material making up the layer, the linear absorption coefficient (absorbing power) of the material, and the thickness of the layer. While other assumptions could be made, those most often used are those of normal incidence of a directed beam of light, with internal and external reflection from the surface being the same.
Determining the A, R, T fractions for a surface
For the special case where the incident radiation is normal (perpendicular) to a surface and the absorption is negligible, the intensity of the reflected and transmitted beams can be calculated from the refractive indices η1 and η2 of the two media, where is the fraction of the incident light reflected, and is the fraction of the transmitted light:
, , with the fraction absorbed taken as zero ( = 0 ).
Illustration
For a beam of light traveling in air with an approximate index of refraction of 1.0, and encountering the surface of a material having an index of refraction of 1.5:
,
Determining the A, R, T fractions for a sheet
There is a simplified special case for the spectroscopic parameters of a sheet. This sheet consists of three plane parallel layers (1:front surface, 2:interior, 3:rear surface) in which the surfaces both have the same remission fraction when illuminated from either direction, regardless of the relative refractive indices of the two media on either side of the surface. For the case of zero absorption in the interior, the total remission and transmission from the layer can be determined from the infinite series, where is the remission from the surface:
These formulas can be modified to account for absorption. Alternatively, the spectroscopic parameters of a sheet (or slab) can be built up from the spectroscopic parameters of the individual pieces that compose the layer: surface, interior, surface. This can be done using an approach developed by Kubelka for treatment of inhomogeneous layers. Using the example from the previous section: { , , } {, , }.
We will assume the interior of the sheet is composed of a material that has Napierian absorption coefficient of 0.5 cm−1, and the sheet is 1 mm thick (). For this case, on a single trip through the interior, according to the Bouguer-Lambert law, , which according to our assumptions yields and . Thus { , , }.
Then one of Benford's equations can be applied. If , and are known for layer and and are known for layer , the ART fractions for a sample composed of layer and layer are:
(The symbol means the reflectance of layer when the direction of illumination is antiparallel to that of the incident beam. The difference in direction is important when dealing with inhomogeneous layers. This consideration was added by Paul Kubelka in 1954. He also pointed out that transmission was independent of the direction of illumination, but absorption and remission were not.)
Illustration
Step 1: We take layer 1 as x, and layer 2 as y. By our assumptions in this case, { }.
Step 2: We take the result from step 1 as the value for new x [ x is old x+y; (-x) is old y+x ], and the value for layer 3 as new y.
Dahm has shown that for this special case, the total amount of light absorbed by the interior of the sheet (considering surface remission) is the same as that absorbed in a single trip (independent of surface remission). This is borne out by the calculations.
The decadic absorbance () of the sheet is given by:
Determining the A, R, T fractions for n layers
The Stokes Formulas can be used to calculate the ART fractions for any number of layers. Alternatively, they can be calculated by successive application of Benford's equation for "one more layer".
If , , and are known for the representative layer of a sample, and , and are known for a layer composed of representative layers, the ART fractions for a layer with thickness of are:
Illustration
In the above example, { }. The Table shows the results of repeated application of the above formulas.
Absorbing Power: The Scatter Corrected Absorbance of a sample
Within a homogeneous media such as a solution, there is no scatter. For this case, the function is linear with both the concentration of the absorbing species and the path-length. Additionally, the contributions of individual absorbing species are additive. For samples which scatter light, absorbance is defined as "the negative logarithm of one minus absorptance (absorption fraction: ) as measured on a uniform sample". For decadic absorbance, this may be symbolized as: . Even though this absorbance function is useful with scattering samples, the function does not have the same desirable characteristics as it does for non-scattering samples. There is, however, a property called absorbing power which may be estimated for these samples. The absorbing power of a single unit thickness of material making up a scattering sample is the same as the absorbance of the same thickness of the materiel in the absence of scatter.
Illustration
Suppose that we have a sample consisting of 14 sheets described above, each one of which has an absorbance of 0.0222. If we are able to estimate the absorbing power (the absorbance of a sample of the same thickness, but having no scatter) from the sample without knowing how many sheets are in the sample (as would be the general case), it would have the desirable property of being proportional to the thickness. In this case, we know that the absorbing power (scatter corrected absorbance) should be: {14 x the absorbance of a single sheet} . This is the value we should have for the sample if the absorbance is to follow the law of Bouguer (often referred to as Beer's law).
In the Table below, we see that the sample has the A,R,T values for the case of 14 sheets in the Table above. Because of the presence of scatter, the measured absorbance of the sample would be: . Then we calculate this for the half sample thickness using another of Benford's equations. If , and are known for a layer with thickness , the ART fractions for a layer with thickness of are:
In the line for half sample [S/2], we see the values which are the same as those for 7 layers in the Table above, as we expect. Note that . We desire to have the absorbance be linear with sample thickness, but we find when we multiply this value by 2, we get , which is a significant departure from the previous estimate for the absorbing power.
The next iteration of the formula produces the estimate for A,R,T for a quarter sample: . Note that this time the calculation corresponds to three and a half layers, a thickness of sample that cannot exist physically.
Continuing for the sequentially higher powers of two, we see a monotonically increasing estimate. Eventually the numbers will start jumping with round off error, but one can stop when getting a constant value to a specified number of significant figures. In this case, we become constant to 4 significant figures at 0.3105, which is our estimate for the absorbing power of the sample. This corresponds to our target value of 0.312 determined above.
Expressing particulate mixtures as layers
If one wants to use a theory based on plane parallel layers, optimally the samples would be describable as layers. But a particulate sample often looks a jumbled maze of particles of various sizes and shapes, showing no structured pattern of any kind, and certainly not literally divided into distinct, identical layers. Even so, it is a tenet of Representative Layer Theory that for spectroscopic purposes, we may treat the complex sample as if it were a series of layers, each one representative of the sample as a whole.
Definition of a representative layer
To be representative, the layer must meet the following criteria:
• The volume fraction of each type of particle is the same in the representative layer as in the sample as a whole.
• The surface area fraction of each type of particle is the same in the representative layer as in the sample as a whole.
• The void fraction of the representative layer is the same as in the sample.
• The representative layer is nowhere more than one particle thick. Note this means the “thickness” of the representative layer is not uniform. This criterion is imposed so that we can assume that a given photon of light has only one interaction with the layer. It might be transmitted, remitted, or absorbed as a result of this interaction, but it is assumed not to interact with a second particle within the same layer.
In the above discussion, when we talk about a “type” of particle, we must clearly distinguish between particles of different composition. In addition, however, we must distinguish between particles of different sizes. Recall that scattering is envisioned as a surface phenomenon and absorption is envisioned as occurring at the molecular level throughout the particle. Consequently, our expectation is that the contribution of a “type” of particle to absorption will be proportional to the volume fraction of that particle in the sample, and the contribution of a “type” of particle to scattering will be proportional to the surface area fraction of that particle in the sample. This is why our “representative layer” criteria above incorporate both volume fraction and surface area fraction. Since small particles have larger surface area-to-volume ratios than large particles, it is necessary to distinguish between them.
Determining spectroscopic properties of a representative layer
Under these criteria, we can propose a model for the fractions of incident light that are absorbed (), remitted (), and transmitted () by one representative layer.
, ,
in which:
• is the fraction of cross-sectional surface area that is occupied by particles of type .
• is the effective absorption coefficient for particles of type .
• is the remission coefficient for particles of type .
• is the thickness of a particle of type in the direction of the incident beam.
• The summation is carried out over all of the distinct “types” of particle.
In effect, represents the fraction of light that will interact with a particle of type , and and quantify the likelihood of that interaction resulting in absorption and remission, respectively.
Surface area fractions and volume fractions for each type of particle can be defined as follows:
, , ,
in which:
• is the mass fraction of particles of type i in the sample.
• is the fraction of occupied volume composed of particles of type i.
• is the fraction of particle surface area that is composed of particles of type i.
• is the fraction of total volume composed of particles of type i.
• is the fraction of cross-sectional surface area that is composed of particles of type i.
• is the density of particles of type i.
• is the void fraction of the sample.
This is a logical way of relating the spectroscopic behavior of a “representative layer” to the properties of the individual particles that make up the layer. The values of the absorption and remission coefficients represent a challenge in this modeling approach. Absorption is calculated from the fraction of light striking each type of particle and a “Beer’s law”-type calculation of the absorption by each type of particle, so the values of used should ideally model the ability of the particle to absorb light, independent of other processes (scattering, remission) that also occur. We referred to this as the absorbing power in the section above.
List of principle symbols used
Where a given letter is used in both capital and lower case form (, and , ) the capital letter refers to the macroscopic observable and the lower case letter to the corresponding variable for an individual particle or layer of the material. Greek symbols are used for properties of a single particle.
– absorption fraction of a single layer
– remission fraction of a single layer
– transmission fraction of a single layer
An, Rn, Tn – The absorption, remission, and transmission fractions for a sample composed of n layers
α – absorption fraction of a particle
β – back-scattering from a particle
σ – isotropic scattering from a particle
– absorption coefficient defined as the fraction of incident light absorbed by a very thin layer divided by the thickness of that layer
– scattering coefficient defined as the fraction of incident light scattered by a very thin layer divided by the thickness of that layer
References
Spectroscopy | Representative layer theory | [
"Physics",
"Chemistry"
] | 4,197 | [
"Instrumental analysis",
"Molecular physics",
"Spectroscopy",
"Spectrum (physical sciences)"
] |
67,525,474 | https://en.wikipedia.org/wiki/Vertebrate%20Genomes%20Project | The Vertebrate Genomes Project (VGP) is a project which aims to generate high-quality, complete reference genomes of all 66,000 vertebrate species. It is an international cooperation project with members from more than 50 separate institutions and was launched in February 2017.
In October 2021, VGP partnered with Colossal Biosciences to sequence and assemble elephant genomes for preservation purposes.
In April 2022, VGP partnered with the Human Genome Project and the African BioGenome Project for sequencing research.
In July 2022, VGP and Colossal Biosciences announced that they successfully sequenced the entire Asian elephant genome; this is the first time that mammalian genetic code has been fully sequenced to this degree since the Human Genome Project was completed in the early 2000s.
In November 2022, VGP successfully sequenced the Nile Rat genome in order to facilitate research on type 2 diabetes and the health effects of circadian rhythm disruption. Not only did researchers sequence an individual rat, but they also sequenced both its parents, allowing them to separate the original rat’s alleles by parental haplotype. The resulting sequence showed that the vast majority of expected protein-coding genes were accounted for.
References
External links
Vertebrate Genomes Project
Genome projects
Bioinformatics | Vertebrate Genomes Project | [
"Engineering",
"Biology"
] | 262 | [
"Bioinformatics",
"Biological engineering",
"Genome projects"
] |
67,525,526 | https://en.wikipedia.org/wiki/Tectonics%20on%20icy%20moons | Tectonic activity has been studied on several icy moons.
Background
Igneous activity on icy moons can be defined as the melting, ascension, and solidification of liquids, particularly water and its ice polymorphs. Tectonic features on icy lithospheres occur by global and regional stresses acting on the moon's interior. Fractures in the icy lithosphere influence the mechanisms by which the lithosphere reacts to stress. An unfractured ice lithosphere has a greater shear strength than tensile strength, and accordingly, compressional deformation must occur by shear failure and cause thrust and strike-slip faulting. Conversely, prefractured ice has much less shear strength, and extensional stress will produce normal faults and graben.
Residual heat from accretion is one possible source of internal heat for icy moons. But only moons with radii greater than about 2000 km are thought to be massive enough to melt pure water-ice in the outer layers. Tidal heating and the decay of radioactive elements are another possible source of internal heat on icy moons. Warming of a cold interior would cause the satellite to expand and undergo tensional stress on the surface. Cooling, on the other hand, would cause contraction and compression. Mantle convection likely occurred within most icy moons, but is not an important source of lithospheric stress.
Asteroid and comet impacts are another source of thermal and seismic energy on icy moons. Impacts could produce melt pools, reactivation of older faults and/or cracks, and deformation to the region antipodal to the impact site. Impacts may impart three general fracture patterns on the icy moon: (1) a global system of radially symmetric fractures originating from the impact site, (2) concentric and radial fractures, and (3) collapse of an impact basin with radial and concentric troughs.
Most icy satellites rotate synchronously. If the satellite rotated more rapidly during formation, rotation becomes synchronous within 1,000-1,000,000 years due to tidal friction. A decrease in rotational speed decreases the oblateness of the icy moon, which reduces principle stress in the north–south direction, thereby creating east–west trending dikes. If tidal friction causes the lithosphere to fail, east west extensional features should be expected near the poles, northeast/northwest strike slip features at mid-latitudes, and north–south compressional features at the equator. The transfer of angular momentum from the planet to the orbiting moon causes the moon's orbital distance to increase with time. As a consequence of increasing orbital distance, the tidal bulge decreases. These stresses should produce compression at the planet facing and antipode positions, extension at the poles, and strike-slip faults oriented northeast/northwest elsewhere.
Plate tectonics
Some of the satellites of Jupiter have features that may be related to plate-tectonic style deformation, although the materials and specific mechanisms may be different from plate-tectonic activity on Earth. On 8 September 2014, NASA reported finding evidence of plate tectonics on Europa, a satellite of Jupiter—the first sign of subduction activity on another world other than Earth.
Titan, the largest moon of Saturn, was reported to show tectonic activity in images taken by the Huygens probe, which landed on Titan on January 14, 2005.
The mechanisms of plate tectonics on icy moons, particularly Earth-like plate tectonics are not widely agreed upon or well understood. Plate tectonics on Earth is hypothesized to be driven by “slab pull,” where the sinking of the more dense subducting plate provides the spreading force for mid-ocean ridges. “Ridge push” is comparatively weak in Earth's plate tectonics. Extensional features are abundant on icy moons, but compressional features are sparse. Furthermore, subducting less dense ice into a more dense fluid is difficult to explain. Force balance modeling suggests that subduction is likely to create large scale topographic forcing across icy moons, because the buoyant force is orders of magnitude greater than subducting forces. Fracturing and plate-like motion is more easily explained by volume changes and ice-shell motion that is decoupled from interior motion.
Tectonic and volcanic features
Trough and Scarp Sets
Linear troughs, chains of pits, and scarps in coherent orientations have been observed on Mimas, Tethys, Rhea, Iapetus, Umbriel, Europa, and Ganymede. These features are thought to be formed from impacts or tidal forcing.
Scarps and troughs traversing older material
These features are similar in appearance to trough and scarp sets, but appear geologically distinct from the terrain in which they traverse. It is thought that the troughs are younger material. These features are considered normal faults and rifts formed by extensional tectonics. However, on Dione and Tethys, large impacts may have produced traversing scarps and troughs.
Linear and curvilinear ridges
Ridges are uncommon, but have been observed on Rhea, Dione, and Ganymede. Ridges are thought to form by compression or transpression.
Concentric and radial scarps and furrows
Collapsed impact basins are thought to form concentric and radial scarps. The Valhalla ring system on Callisto is one of the most well-preserved examples of these features. Concentric furrows on Ganymede's dark terrain appear, but only as troughs and without scarps.
Volcanism
Four processes may produce volcanic activity on icy moons: (1) mantle convection, (2) negative diapirism, (3) impact cratering, and (4) antipodal fracturing in response to a large impact. The strongest evidence for volcanism is found in the polygonal coronae on Miranda, a large, fractured and resurfaced region embedded within a heavily cratered region.
Grooved terrain
Grooved terrain refers to features that are parallel or subparallel, dissect older terrain, are often associated with lighter colored terrain, and are negative relief structures rather than raised. The negative topography suggests that these features formed from global expansion of the icy moon, although some suggest the features formed by reactivation of older structures.
Observations
Europa
Voyager 2 and Galileo mission imagery revealed a highly fractured surface on Europa devoid of cratering, suggesting that the surface is regularly young and subject to resurfacing. Dilational bands appear morphologically similar to spreading ridges on Earth, and therefore suggest that warm ice ascends upwards to form the bands. However, compressional deformation features are sparse and too small to accommodate spreading from the dilational bands. A subduction mechanism is a key to the ice tectonics hypothesis on Europa. For subduction to occur, convection within or below the ice crust must exert stresses that exceed the strength of the overlying ice crust. But to hold a tenable tectonics hypothesis, one must explain how ice sinks below the surface. If the crustal ice porosity exceeds ~1%, subduction is unlikely, but the high concentrations of salt within the ice make subduction possible with porisities up to 10%. Subduction may occur if differences in salt content exceed 5% between the overriding plate and the subducting plate. However, the processes and conditions that initiate subduction are still poorly explained.
Europa's ice crust may be fractured by tidal stresses from Jupiter, and it has been hypothesized that liquid water could reach the surface through these cracks. However, the ice overburden pressure within the crust exceeds tidal stresses at depths greater than 35 m below the ice surface, thereby limiting the depth at which tidally-induced cracks can propagate. Furthermore, liquid water within any cracks will rapidly freeze. Therefore, a source other than tidal forcing must place the crust under tension for cracks to propagate deeply. Tides may force strike-slip motion along cracks, and this lateral motion would produce heat within the crack and make the ice more susceptible to ductile flow. The warmer and less viscous ice along the cracks is less dense than the surrounding ice, and may flow upwards to the surface. Melt generated within these fractures may briefly exist near the surface before percolating downward to the subsurface ocean over thousand year timescales.
Truncated surface features suggest that subduction on Europa may occur along tabular zones. Unlike subduction on Earth, differences in the strengths and relative densities of Europan ice, it is unlikely that the subducting ice plate is “pulled” into the subsurface ocean. Instead, it is most likely incorporated into the ice composing the overriding plate. Surface features that intersect tabular zones do not continue on the other side, unlike across strike-slip and dilational faults.
Strike-slip faults in the northern hemisphere of Europa are predominantly left-lateral, while those in the southern hemisphere are predominantly right-lateral. This dichotomy becomes more pronounced the further the fault is from the equator. To explain this, the shell tectonics hypothesis describes a mechanism for strike-slip motion along faults driven by tidal forces from Jupiter. Numerical simulations of shell tectonics strike-slip faulting agrees closely with observations. However, the shell tectonics model requires that a substantial number of fractures or faults already exist on the surface.
Convection and advection within the liquid ocean can transport and freeze liquid water into the ice crust, and that ocean-origin material may potentially reach the surface. However, the forces that drive extension in the ice crust are not well known. Slab pull, where a subducting ice plate pulls the crust apart at divergent boundaries is unlikely to drive extension because ice is less dense than liquid water, and therefore unable to sink into the subsurface ocean.
Ganymede
Ganymede has two principle geologic units termed “dark” terrain and “bright” terrain. Bright terrain is hypothesized to be younger because it has fewer craters than the dark terrain. The topography of bright terrain has many linear grooves in some regions, while it appears smooth in others. The appearance of smooth terrain may be an artifact of low resolution Voyager 2 imagery. Bright bands are hypothesized to form by tectonic spreading, possibly analogous to mid-ocean ridge spreading or terrestrial rift spreading. In some regions, dark terrain patches are found within light terrain. Parmentier et al. (1982) suggests that the light terrain material flooded into the dark terrain, leaving dark topographic highs as the observed dark patches surrounded by lower elevation light terrain. Parmentier et al. (1982) find that mid-ocean ridge-like spreading does not occur on Ganymede, citing observations of poorly matched crater remnants and poorly fitting polygonal terrain in regions split by rifts. Instead, offset features and evidence of flooding suggest finite lithospheric rifting produces the bright terrain. Parmentier et al. (1982) infer that the dark terrain is an ice-silicate mixture that is slightly more dense than pure water ice. Extension in the dark terrain causes less dense water-ice to extrude upwards, forming linear and curve rifts of bright terrain. Long, narrow grooves appear in both bright and dark terrains, but are more abundant in light terrain. Grooves are typically symmetrical, which suggests that they are extensional features, rather than compressional features like folds or thrust faults.
Head et al. (2002) reexamine possible formation mechanisms of bright and dark terrains on Ganymede using higher resolution Galileo mission imagery, with particular interest in whether the smooth areas described in Parmentier et al. (1982) are produced by cryovolcanic infilling. Many of the smooth regions observed in Voyager 2 imagery appear that way due to low image resolution. Instead, these “smooth” regions hold smaller linear ridges and troughs. The presence of smooth terrain was key to the cryovolcanic infilling hypothesis, and the presence of ridges and troughs within these regions poses a substantial challenge to that hypothesis. Galileo imagery reveals no lobate features or vents indicative of cryovolcanic flow. Furthermore, in regions with both bright and dark terrain, the bright terrain is topographically higher. These observations demand a tectonic deformation, possibly in addition to cryovolcanism, to explain bright regions.
Linear grooves and furrows thousands of kilometers in length form concentric arcs on Ganymede's surface. Rossi et al. (2018) undertook a detailed tectonic survey of Ganymede, using a combination of Voyager 2 and Galileo mission imagery, to inform an evolutionary tectonic model for the Uruk Sulcus region. Right lateral faulting produces sigmoidal structures in the shear zone, where extensional forces create linear grooves and furrows.
Abundant evidence of strike-slip faulting on Ganymede exists in both bright and dark terrain types. Such faulting may expose fresh, light ice within dark terrains. The fields of mapped faults may give evidence of how stress patterns shifted through time to produce the terrain.
References
Moons
Plate tectonics
Geology
Planetary science | Tectonics on icy moons | [
"Astronomy"
] | 2,700 | [
"Planetary science",
"Astronomical sub-disciplines"
] |
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