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22,519,650 | https://en.wikipedia.org/wiki/Fast%20Universal%20Digital%20Computer%20M-2 | The M-2 () was a computer developed at the Laboratory of Electrical Systems in the Institute of Energy of the USSR Academy of Sciences. The successor to the M-1, it was developed in 1952 by a team of engineers led by I.S. Brook (or Bruk).
The computer was developed and assembled in the period between April and December 1952. In 1953 M-2 became fully operational and was used for solving applied problems on round-the-clock basis, mostly having to do with nuclear fission and rocket design.
M-2 was the basis for several other Soviet computers, some of them developed at other research institutes.
References
External links
Google translation
Soviet computer systems
Soviet inventions | Fast Universal Digital Computer M-2 | Technology | 141 |
68,859,982 | https://en.wikipedia.org/wiki/Institute%20of%20Evolutionary%20Biology | The Institute of Evolutionary Biology (In Spanish Instituto de Biología Evolutiva IBE (CSIC-UPF) is a joint research center of Pompeu Fabra University (UPF) and the Spanish National Research Council (CSIC) founded in 2008. IBE is the only research center in Catalonia and the rest of Spain that is entirely dedicated to evolutionary biology and natural resources.
The research carried out by IBE focuses on the study of the processes and mechanisms for the generation and maintenance of biodiversity and its conservation. This is one of the most important scientific challenges of the 21st century, as evidenced by new global initiatives to sequence the genomes of all known species and discover the remaining 80 percent of currently unknown species, including the Earth BioGenome Project. To meet this global challenge requires the methods and concepts of evolutionary biology; and in particular, the understanding of the bases of the differences between organisms, both between species and within them, and how these differences produce new functions and interactions, which will determine the basic mechanisms of life and place biodiversity in a robust evolutionary framework. To this end, IBE research uses the new tools available, experimental and computational, to understand the basic functioning of life, discover the mechanisms for generating biological innovations and preserve biodiversity and promote its management in a sustainable way.
In July 2008, Dr. Xavier Bellés was appointed director of the IBE. In February 2017 he was succeeded in office by Dr. Tomàs Marquès-Bonet as director of the center. Since May 2020, the IBE has been headed by Dr. Salvador Carranza.
Academics
The scientific activity of IBE is organized in 5 interrelated research programs:
Animal Biodiversity and Evolution
Comparative and Computational Genomics
Functional Genomics and Evolution
Population Genetics
Complex Systems
Campus
IBE employs more than one hundred and thirty people, distributed among the neighboring buildings of the Barcelona Biomedical Research Park (PRBB) and the Mediterranean Center for Marine and Environmental Research (CMIMA). Currently, IBE is in the process of moving to a new campus at the Mercat del Peix, an innovation complex, focused on biomedicine, biodiversity, and planetary well-being, which will be located next to the UPF Ciutadella campus and the Ciutadella Park. The Mercat del Peix project will involve the construction of three new buildings, which will house the Institute of Evolutionary Biology (IBE), the Barcelona Institute of Science and Technology (BIST) and a new complex at the Pompeu Fabra University (UPF). These will be built on the area of 7,500 square meters that is currently a car park and which was, until the middle of the 20th century, the central fish market of Barcelona (Mercat del Peix). The works will begin in April 2022 and the first researchers will begin to work at the center in the first half of 2025. The project is promoted by the City Council of Barcelona and UPF, with the participation of two strategic partners, the Spanish National Research Council and BIST.
Notable faculty
Carles Lalueza-Fox (Ancient DNA)
Luc Steels (Artificial Intellence)
See also
Pompeu Fabra University Notable Faculty
References
External links
Institute of Evolutionary Biology CSIC - Pompeu Fabra University website.
Education in Barcelona
Research institutes established in 2008
Evolutionary biology
Research institutes in Catalonia
Pompeu Fabra University | Institute of Evolutionary Biology | Biology | 690 |
291,229 | https://en.wikipedia.org/wiki/Epigraph%20%28literature%29 | In literature, an epigraph is a phrase, quotation, or poem that is set at the beginning of a document, monograph or section or chapter thereof. The epigraph may serve as a preface to the work; as a summary; as a counter-example; or as a link from the work to a wider literary canon, with the purpose of either inviting comparison or enlisting a conventional context.
A book may have an overall epigraph that is part of the front matter, or one for each chapter.
Examples
As the epigraph to The Sum of All Fears, Tom Clancy quotes Winston Churchill in the context of thermonuclear war: "Why, you may take the most gallant sailor, the most intrepid airman or the most audacious soldier, put them at a table together – what do you get? The sum of their fears."
Sir Walter Scott frequently used epigraphs in his historical novels, including throughout his Waverley novels.
The long quotation from Dante's Inferno that prefaces T. S. Eliot's "The Love Song of J. Alfred Prufrock" is part of a speech by one of the damned in Dante's Hell.
The epigraph to E. L. Doctorow's Ragtime quotes Scott Joplin's instructions to those who play his music, "Do not play this piece fast. It is never right to play ragtime fast."
The epigraph to Fyodor Dostoyevsky's The Brothers Karamazov is John 12:24: "Verily, verily, I say unto you, except a corn of wheat fall into the ground and die, it abideth alone: but if it die, it bringeth forth much fruit."
The epigraph to Eliot's Gerontion is a quotation from Shakespeare's Measure for Measure.
Eliot's "The Hollow Men" uses the line "Mistah Kurtz, he dead" from Joseph Conrad's Heart of Darkness as one of its two epigraphs.
As an epigraph to The Sun Also Rises, Ernest Hemingway quotes Gertrude Stein, "You are all a lost generation."
The epigraph to Theodore Herzl's Altneuland is "If you will it, it is no dream..." which became a slogan of the Zionist movement.
Louis Antoine de Saint-Just's line "Nobody can rule guiltlessly" appears before chapter one in Arthur Koestler's 1940 anti-totalitarian novel Darkness at Noon.
A Samuel Johnson quotation serves as an epigraph in Hunter S. Thompson's novel Fear and Loathing in Las Vegas: "He who makes a beast of himself gets rid of the pain of being a man."
Stephen King uses many epigraphs in his writing, usually to mark the beginning of another section in a novel. An unusual example is The Stand wherein he uses lyrics from certain songs to express the metaphor used in a particular part.
Jack London uses the first stanza of John Myers O'Hara's poem "Atavism" as the epigraph to The Call of the Wild.
Cormac McCarthy opens his 1985 novel Blood Meridian with three epigraphs: quotations from French writer and philosopher Paul Valéry, from German Christian mystic and Gnostic Jacob Boehme, and a 1982 news clipping from the Yuma Sun reporting the claim of members of an Ethiopian archeological excavation that a fossilized skull three hundred millennia old seemed to have been scalped.
The epigraphs to the preamble of Georges Perec's Life: A User's Manual (La Vie mode d'emploi) and to the book as a whole warn the reader that tricks are going to be played and that all will not be what it seems.
J. K. Rowling's novels frequently begin with epigraphs relating to the themes explored. For example, Harry Potter and the Deathly Hallows opens with two: a quotation from Aeschylus's tragedy The Libation Bearers and a quotation from William Penn.
Quotation from Woodrow Wilson's The State on the title page of every issue of The Bohemian Review, a magazine endorsing independence of Czechs and Slovaks to Austria-Hungary in 1917–1918 (example).
Fictional quotations
Some writers use as epigraphs fictional quotations that purport to be related to the fiction of the work itself. Examples include:
In films
The film Le Samouraï opens with a fictional quotation from the Bushido.
The film Talladega Nights: The Ballad of Ricky Bobby opens with a fictional quotation attributed to Eleanor Roosevelt for comedic effect.
In literature
Some science fiction works, such as Isaac Asimov's Foundation Trilogy, Frank Herbert's Dune series, and Jack McKinney's Robotech novelizations use quotations from an imagined future history of the period of their story.
Fantasy literature may also include epigraphs. For example, Ursula K. Le Guin's Earthsea series includes epigraphs supposedly quoted from the epic poetry of the Earthsea archipelago.
Elizabeth C. Bunce's Edgar Award-winning Myrtle Hardcastle mystery series, beginning with Premeditated Myrtle includes epigraphs by the fictional 19th century scholar H.M. Hardcastle at the beginning of each chapter of the five-book series.
The first and last books of Diane Duane's Rihannsu series of Star Trek novels pair quotations from Lays of Ancient Rome with imagined epigraphs from Romulan literature.
F. Scott Fitzgerald's The Great Gatsby carries on title page a poem called from its first hemistich "Then Wear the Gold Hat," purportedly signed by Thomas Parke D'Invilliers. D'Invilliers is a character in Fitzgerald's first novel, This Side of Paradise.
This cliché is parodied by Diana Wynne Jones in The Tough Guide To Fantasyland.
Jasper Fforde's The Eyre Affair has quotations from supposedly future works about the action of the story.
John Green's The Fault in Our Stars has a quotation from a fictitious novel, An Imperial Affliction, which features prominently as a part of the story.
Stephen King's The Dark Half has epigraphs taken from the fictitious novels written by the protagonist.
Dean Koontz's The Book of Counted Sorrows began as a fictional book of poetry from which Koontz would "quote" when no suitable existing option was available; Koontz simply wrote all these epigraphs himself. Many fans, rather than realizing the work was Koontz' own invention, apparently believed it was a real, but rare, volume; Koontz later collected the existing verse into an actual book.
The Ring Verse at the beginning of J. R. R. Tolkien's The Lord of the Rings describes the Rings of Power, the central plot device of the novel.
Akame Majyo's Time Anthology begins each chapter with an excerpt from a fictional grimoire.
Brandon Sanderson, in his Mistborn and Stormlight Archive series uses various epigraphs including letters between various gods, so-called "death rattles" and quotes from the villain's diary.
Edward Gorey's The Unstrung Harp is not only about a fictitious novel, but its author thinks of a fictional verse for its epigraph.
See also
Epigram, a brief, interesting, memorable, and sometimes surprising or satirical statement
Incipit, the first few words of a text, employed as an identifying label
Flavor text, applied to games and toys
Prologue, an opening to a story that establishes context and may give background
Keynote, the first non-specific talk on a conference spoken by an invited (and usually famous) speaker in order to sum up the main theme of the conference.
References
Bibliography
External links
Opening Quotes: an ever-growing collection of literary epigraphs
Epigraph at Literary Devices
Literature
Book design
Quotations
sv:Motto | Epigraph (literature) | Engineering | 1,664 |
22,270,456 | https://en.wikipedia.org/wiki/SUPER%20HI-CAT | C-MORE: SUPER HI-CAT (Center for Microbial Oceanography- Research and Education: Survey of Underwater Plastic Ecosystem Response Hawaii to California Transit)
The SUPER HI-CAT research cruise was the first effort to study the microbial communities and the biogeochemistry associated with the Great Pacific Garbage Patch.[1] The study was conducted aboard the RV Kilo Moana (T-AGOR-26) between August 25, 2008 and September 5, 2008 by researchers from University of Hawaiʻi at Mānoa, Oregon State University, and the Algalita Marine Research Foundation.
Previous research on the Plastic Patch had mostly focused on the effects of the plastic pieces on jellyfish, fish, sea turtles, and seabirds. Relatively little was known about how this type of marine debris would affect the microbial communities that make up 98% of the biomass in the ocean and control oceanic biogeochemistry. During this cruise, 30 sites were sampled. At 15 of these sites, a modified surface net called a manta trawl was used to collect plastic pieces, while water samples were collected from the upper 200 meters of the ocean. At the other 15 stations, only the surface waters were sampled. This study will allow researchers to begin to determine whether biofilms are forming on the plastic particles, whether the microbes living on the particles are different from the free-living planktonic organisms, and what effect these communities might have on the oceanic carbon cycle and nitrogen cycle.
See also
Project Kaisei
References
External links
Biological oceanography
Pacific expeditions
Oceanographic expeditions
Biogeochemistry | SUPER HI-CAT | Chemistry,Environmental_science | 324 |
65,669,827 | https://en.wikipedia.org/wiki/Richard%20Oreffo | Richard Okagbue Chude Oreffo is a British–Nigerian physician and Professor of Musculoskeletal Science at the University of Southampton. His research considers skeletal biology and the fundamental mechanisms that underpin skeletal stem cell differentiation. In 2020, he launched the Cowrie Scholarship Foundation, which supports Black British students in their university studies.
Early life and education
Oreffo is a British–Nigerian. As an undergraduate student Oreffo specialised in biochemistry at the University of Liverpool. Oreffo completed doctoral research at the University of Oxford, where he investigated Vitamin A and bone. Oreffo was a postdoctoral scholar at the University of Texas Health Science Center at San Antonio. Here he worked with Gregory Mundy, an expert in bone and mineral research. He returned to the United Kingdom in 1989, where he joined Zeneca as a principal research scientist. In 1993 Oreffo was awarded a Medical Research Council fellowship, and joined the University of Oxford.
Research and career
In 1999, Oreffo joined the University of Southampton, where he led the Bone and Joint Research Group. He was made Professor in 2004. Oreffo specialises in skeletal biology, with a focus on the mechanisms that underpin differentiation of skeletal stem cells and bone regeneration. His early work looked to create new, nanostructured surfaces capable of efficiently growing adult stem cells. In 2004 he founded the Centre for Human Development, Stem Cells and Regeneration.
Oreffo combined stem cells and degradable plastic to create an artificial bone, which incorporated a honeycomb-like scaffold to allow blood to flow through it. The flow of blood encourages a patient's own stem cells to attach to the artificial structure, which results in the growth of new bone. Eventually, the plastic degrades, and the structure is replaced by newly formed bone. The degradable plastic is a blend of three different materials.
After successfully realising artificial bone, Oreffo created the spinout company Renovos, who fabricate new materials for tissue repair. In early 2020 the non-profit Orthopaedic Research UK made an investment in Renovos, representing their first investment in a technology startup.
Awards and honours
2001 Maxime Hanns Award
2010 Medical Technology Awards Grand Prix
2015 Elected Fellow of the Royal Society of Biology
2019 Elected Fellow of International Orthopaedic Research
Academic service
In 2008, Oreffo was made the University of Southampton Associate Dean International and Enterprise. In 2015 Oreffo returned to the University of Oxford, where he completed a Doctor of Science in skeletal tissue engineering. Oreffo established the Cowrie Scholarship Foundation in 2020, a scheme which looks to provide financial support to 100 disadvantaged Black British students to attend universities in the United Kingdom between 2021 and 2031.
Selected publications
References
Year of birth missing (living people)
Living people
Place of birth missing (living people)
British people of Nigerian descent
Alumni of the University of Liverpool
Alumni of the University of Oxford
Academics of the University of Oxford
Academics of the University of Southampton
University of Texas Health Science Center at San Antonio faculty
21st-century British medical doctors
Stem cell researchers
Fellows of the Royal Society of Biology
Officers of the Order of the British Empire | Richard Oreffo | Biology | 643 |
26,345,629 | https://en.wikipedia.org/wiki/C16H10O6 | {{DISPLAYTITLE:C16H10O6}}
The molecular formula C16H10O6 (molar mass: 298.24 g/mol, exact mass: 298.0477 u) may refer to:
Irilone
Fallacinal | C16H10O6 | Chemistry | 58 |
7,864,806 | https://en.wikipedia.org/wiki/Process%20and%20General%20Workers%27%20Union | The Process and General Workers' Union was a British trade union representing workers involved in mining and processing salt, and related industries, mostly in Cheshire.
History
The union was founded in November 1888, as the Northwich Amalgamated Society of Salt Workers, Rock Salt Miners, Alkali Workers, Mechanics and General Labourers. Six months later, William Yarwood took over as its general secretary, resolving numerous industrial disputes. He brought the union into the Trades Union Congress, and the National Transport Workers' Federation. It was based at the Vine Tavern in Northwich, then in the 1920s moved to the George and Dragon.
In 1951, the union had 2,196 members, and renamed itself as the Mid-Cheshire Salt and Chemical Industries Allied Workers' Union, and in 1966 it became the Process and General Workers' Union. Three years later, it merged into the Transport and General Workers' Union.
General Secretaries
1889: William Yarwood
1918: W. Kettle
C. Yarwood
1945: H. Sutton
1961: R. M. Moss
References
Chemical industry trade unions
Trade unions based in Cheshire
Trade unions established in 1888
Trade unions disestablished in 1969
Transport and General Workers' Union amalgamations | Process and General Workers' Union | Chemistry | 236 |
8,162,512 | https://en.wikipedia.org/wiki/Luting%20agent | A luting agent is a dental cement connecting the underlying tooth structure to a fixed prosthesis. To lute means to glue two different structures together. There are two major purposes of luting agents in dentistry – to secure a cast restoration in fixed prosthodontics (e.g. for use of retaining of an inlay, crowns, or bridges), and to keep orthodontic bands and appliances in situ.
In a complex restoration procedure, the selection of an appropriate luting agent is crucial to its long-term success. In addition to preventing the fixed prosthesis from dislodging, it is also a seal, preventing bacteria from penetrating the tooth-restoration interface.
Zinc phosphate is the oldest material available and has been used in dentistry for more than a century. The introduction of adhesive resin systems made a wide range of dental materials available as luting agents. The choice of luting agent is dependent on clinical factors including dental occlusion, tooth preparation, adequate moisture control, core material, supporting tooth structure, tooth location, etc. Research has determined that no single luting agent is ideal for all applications.
Classification
There are many dental luting agents available. Recently introduced agents such as resins and resin-modified glass-ionomer cement (RMGIC) are claimed to perform better clinically than some traditional ones due to their improved properties. Ultimately, the durability of restoration attached to the tooth surface using lutes depends on several factors, for instance strength of materials used, operator's skills, tooth type, and patient's behaviour.
Dental lutes can be classified in many ways, some of which are based on:
(i) user's knowledge and experience of use
conventional: zinc phosphate, zinc polycarboxylate, and glass-ionomer (GI)
contemporary: resin-modified glass-ionomer cement (RMGIC) and resin
(ii) type of setting mechanism
acid-base reaction: zinc phosphate, zinc polycarboxylate, glass-ionomer
polymerisation: resin-modified glass-ionomer cement (RMGIC) and resin
(iii) the expected duration of use of restoration
definitive (long term): zinc phosphate, zinc polycarboxylate, glass-ionomer, resin-modified glass-ionomers (RMGIC) and resin
provisional (short term): eugenol, non-eugenol, resin, or polycarboxylate-based
Definitive cements
Zinc phosphate
Zinc phosphate is the luting cement that has been about the longest and has become very firmly established. It is still routinely used by almost one-third of UK practitioners today. It is usually made up of a powder (zinc oxide and magnesium oxide) and a liquid (aqueous phosphoric acid). Mixing of zinc phosphate is done by using a spatula to gradually incorporate the powder into the liquid. By using a chilled glass slab, the working time will be increased.
Clinical studies have been carried out and results show that over a ten-year period, zinc phosphate cemented restorations had a lower risk of failure compared to other conventional cements such as glass ionomer or resin-modified glass ionomer. However, it has some well-known clinical disadvantages, including high clinical solubility, lack of adhesion, low setting pH and a low tensile strength.
Zinc polycarboxylate
Zinc polycarboxylate was the first cement to bind to tooth structure. It is generally made up of the same powder as zinc phosphate (zinc oxide and up to 10% magnesium oxide) but uses a different liquid – aqueous copolymer of polyacrylic acid (30–40%).
It has a short working time which can make it difficult to use but this can be elongated by adding tartaric acid, mixing on a cold glass slab or using a lower powder–liquid ratio. In comparison with zinc phosphate, zinc polycarboxylate has been found to be distinctly superior in its adhesion to enamel and dentin under tensile loading.
Glass ionomer
This is the first of the glass ionomer (GI) luting cements to appear in 1978. It consists of fluoroaluminosilicate glass and a liquid containing polyacrylic acid, itaconic acid and water. Alternatively, the acid may be freeze-dried and added to powder with distilled water.
When in position it will release fluoride ions which could have a potential anti-caries effect. It also binds physicochemically to tooth structure and has a low coefficient of thermal expansion, both of which are important to create a good seal and good retention. However, it has been linked with significant postoperative sensitivity. It is also very initially acidic which may cause pulpal inflammation and has a very slow setting reaction, meaning hardening can take up to seven days.
Resin cements
Resin cements are a type of polymerisable lutes. They consist of methacrylate and dimethacrylate monomers (e.g. bisphenol A-glycidyl methacrylate (Bis-GMA), urethane dimethacrylate (UDMA), tri-ethylene glycol dimethacrylate (TEGMA)), filler particles (e.g. quartz, fused silica, aluminosilicates and borosilicates) and an initiator which can be either chemically- or light-activated.
Chemically/self-cured resin cements
Autopolymerisation occurs once all the constituents are mixed together. An external source of energy such as light and heat is not needed to activate the setting reaction. Excess cement should be removed immediately after seating the restoration by using interproximal dental instruments such as dental floss. Autopolymerised cement is proven to be the most radiolucent among all resin cements, making it relatively difficult to be seen on radiographs.
Light-cured resin cements
Due to the presence of light-activated components (photo-initiators), this type of resin cement requires an external light source to initiate the setting reaction. This characteristic allows command set at the periphery of the restoration where light can reach the cement. However, this type of cement is not suitable for thick restorations due to attenuation of light. Instead, a chemically-cured resin cement should be used.
Dual-cured resin cements
They consist of a light-activated paste mixed with a chemical catalyst for resin polymerisation. They are widely used for luting dental restoration whereby the thickness allows penetration of light for partial curing only. On the other hand, the chemically-cured component is key in ensuring complete polymerisation and hence full strength acquisition. Discolouration may occur due to the presence of aromatic amine. Overall, the combination of its physical and chemical properties makes it the most favourable type.
Today resin cements are manufactured in different shades to accommodate demanding aesthetic needs. It is also well known for its high flexural strength, which ranges from 64 to 97 MPa. Although it has the advantage of attaching restorations with minimal retentive capacity to tooth surfaces due to its high bond strength to dentine, its methacrylate constituent causes it to undergo polymerisation shrinkage when setting. The strain introduced by the shrinkage will tend to raise the tensile stresses significantly at areas where the cement is thick. However, the cement thickness usually used is sufficiently low to raise concern. Another way to look at the strain applied onto the tooth structure is to consider the configuration factor (C-factor) of the lute, especially in the case of inlay type restoration. The use of resin cements is considered technique-sensitive as compared to conventional cements because it requires multiple steps for bonding and is difficult to clean up.
Resin-modified glass-ionomer cement (RMGIC)
RMGIC, also known as hybrid cements, was developed with the purpose of eliminating weaknesses of the traditional glass-ionomer (GI) to enhance its existing properties. The addition of polymerisable resins (hydrophilic methacrylate monomers) results in higher compressive and tensile strength, as well as lower solubility, all of which are ideal properties of a dental luting agent. The setting reaction takes place with the relatively quick polymerisation of resins and gradual acid-base reaction of GI. At the early stage of setting reaction, RMGIC has a certain degree of solubility at the margins. Therefore, it is important to keep the margin dry for around 10 minutes to minimise loss of marginal cement.
Theoretically, RMGIC benefits the teeth by releasing fluoride at the marginal area to reduce the risk of tooth decay. However, there is currently no clinical evidence to prove this since the cement film is very thin (only 20–30μm) at the margin.
Provisional or temporary cements
Provisional (or temporary) luting agents are used specifically for inter-appointment fixation of temporary restorations, prior to cementation of a permanent restoration. It is mainly provisional crowns and bridges (fixed partial dentures) that are cemented with eugenol-containing temporary cements, but sometimes they may be used for permanent restorations.
As these temporary restorations will require removal, their ideal properties should consist of poor physical properties, such as low tensile strength and high solubility; as well as no pulp irritability and easy handling. The main examples of temporary luting agents include zinc oxide-eugenol cements, non-eugenol-containing zinc oxide cements and calcium hydroxide pastes.
Zinc oxide-eugenol
Eugenol (4-allyl-2-methoxy phenol) is the principal constituent of clove oil, and when mixed with zinc oxide leads to a chelating reaction. All eugenol reacts to zinc oxide eugenol, meaning none is available to diffuse once setting is complete. Supposedly its therapeutic effects are supported by dentinal tubule fluid promoting the release of eugenol and its penetration towards the pulp.
Zinc oxide-eugenol is often found as a two-paste material when used for temporary cementation. The paste containing zinc oxide often includes mineral or vegetable oils, and the eugenol has fillers incorporated into it to form the other paste.
Zinc oxide-eugenol may present as a powder (zinc oxide) that requires mixing with a liquid (eugenol). The zinc oxide powder may contain up to 8% of other zinc salts (acetate, propionate, or succinate) as accelerators. The liquid containing eugenol has up to 2% of acetic acid added as an accelerator.
Zinc oxide non-eugenol
If cementation of a definitive restoration would require a resin-based luting agent, there is evidence indicating the use of a zinc oxide non-eugenol containing cement. Non-eugenol materials use long-chain aliphatic acids or aryl-substituted butyric acid to react with zinc oxide particles. Eugenol itself is known to be incompatible with resin polymers, as it is a radical scavenger (like other phenolic compounds) and therefore inhibits polymerisation of resin materials.
Further evidence illustrated that the application of eugenol-containing cement to cured composite resin cores before final cementation with resin cement significantly reduced retention of the crowns. It is also worth bearing in mind that a temporary cement's incomplete removal from a cured resin composite core may affect the final restoration's cementation quality.
Clinical applications
Cements can either be permanent (called definitive) or temporary (called provisional):
Definitive cements
Zinc phosphate
Zinc phosphate is used to place metal constructed restorations which are mechanically retentive. The material is also suitable for cementing prefabricated or cast metal post-cores. It can also be used to lute long span bridges.
The use of zinc phosphate in luting a porcelain crown may result in decreased aesthetic properties due to the high concentrations of unreacted zinc oxide, especially if the cement lute margin is visible. To avoid this, the crown margins should be kept within gingival crevice, so that the cement lute remains hidden.
Zinc polycarboxylate
This material is mainly used in attaching crowns and inlays. Due to masticatory forces causing deformation, it can only be used in short-span bridges. Zinc polycarboxylate is adherent to tooth structure such as enamel and dentine, but has weak or no bond with gold and porcelain. This presents limited use when it comes to luting gold or porcelain crowns. However, zinc polycarboxylate bonds to non-precious metal alloys that have been increasingly used in porcelain fused to metal (PFM) crowns.
Zinc polycarboxylate bonds well with stainless steel, and this makes it useful for the attachment of orthodontic bands.
As a result of a high concentration of unreacted zinc oxide cores, zinc polycarboxylate sets opaque. If used in porcelain crowns, this will degrade the aesthetic properties of the restoration if the cement lute is left visible.
Glass ionomer
Glass ionomer cement when combined with retentive preparations produced a high retentive strength when used as a cement for metal copings to uremic teeth.
Glass ionomer cements can be used with metal and metal-ceramic restorations provided they possess adequate retentive and resistance form. They are however, contraindicated for all-ceramic restorations that are low-strength.
It is also suitable for use in amalgam restorations, due to its ability to withstand amalgam condensation. It has been said that GI cements can give more rigid support compared to calcium hydroxide cements, making it popular as a lining material.
Glass ionomer has an aesthetic advantage over zinc phosphate and zinc polycarboxylate when it comes to luting porcelain crowns. This is because of the presence of unreacted cores of glass rather than zinc oxide, therefore making it more translucent. However, improvements are still required to achieve a true match to porcelain.
Glass ionomer has not been recommended for cementing posts, as the vibration caused by tooth preparation may decrease the retention provided by the cement.
In orthodontics, glass ionomer cements are widely used to attach orthodontic bands. The presence of an adhesive seal between the cement and tooth structure additional to fluoride release can help to maintain teeth in good condition throughout orthodontic treatment. However, in practice, the high rate of brackets debonding during treatment has shown that glass ionomer is not a suitable material in this aspect.
Resin modified glass ionomer
RMGIC has demonstrated a successful history when used for both metal and metal ceramic restorations The cement also demonstrated good results with metal and composite fibre posts. However, they do not provide adequate retention when used on tooth preparations with poor retention and resistance forms.
Due to the possibility of hygroscopic expansion, these cements are not recommended for use with all-ceramic restorations that are susceptible to etching and with posts.
Similar to glass ionomer cement, RMGIC can also be used to provide a high retentive strength when used in cementation of metal copings on uremic teeth with retentive preparations.
Resin
Resin cements are widely selected for luting non-metallic restorations, resin bonded bridges, ceramic crowns and porcelain veneers. They are available in a different number of shades, viscosities and aesthetic try-in pastes. These cements are also an option for use with ceramic and resin composite inlays and onlays.
They also demonstrated a favourable outcome when used for all-ceramic restorations, veneers, metal or metal-ceramic restorations with compromised retention and resistance form.
Resin cement is also shown to be useful for cementation of post in endodontically treated teeth.
Self-adhesive cements
Self-adhesive cements do not require intermediate steps to bond tooth structure, unlike resin cements. This gives simplicity and efficiency in its use. They are dual-cured and are most effective when bonded to dentine. It is suitable for cementing all-ceramic crowns, porcelain inlays and onlays.
Self-adhesive resin cements has shown an acceptable clinical result when used for ceramic inlays.
Self-adhesive resin cements also demonstrated high and adequate survival rates when used as a cement for metal ceramic crowns making it a feasible alternative.
Provisional cements
Zinc oxide eugenol
Zinc oxide eugenol is used for luting temporary restorations due to its good sealing abilities but inferior physical properties.
Eugenol-containing cements should be used with caution as the eugenol can contaminate the preparation by inhibiting the polymerization of certain resin based composites which are used as a definitive filling material. They also reduce the bond strength of both total and self-etching adhesive systems to dentin if used before an indirect bonding restoration.
Another report shows that there is no difference in bond strengths of self-adhesive resin cements to dentine between prior application of eugenol free and eugenol containing provisional cements.
Later publications show a reduction in luting agent bond strengths to dentine when eugenol containing provisional cements are used. Nevertheless, contamination of dentine which interference with adhesion of definitive luting agent is inevitable when a provisional cement is used regardless of whether the cement contains eugenol or not.
Selection of luting agent to be used for a given restoration should be based on a basic knowledge of the materials available, the type of restoration to be placed, the requirements of the patient and the expertise and experience of the clinician.
Summary properties of cements
References
Dental materials | Luting agent | Physics | 3,659 |
40,240,350 | https://en.wikipedia.org/wiki/Milan%20Vojnovic | Milan Vojnovic is a professor of data science with the Department of Statistics at the London School of Economics, where he is also director of the MSc Data Science Programme. Prior to this, he worked as a researcher with Microsoft Research from 2004 to 2016.
He received his Ph.D. degree in Technical Sciences from École Polytechnique Fédérale de Lausanne in 2003, and both M.Sc. and B.Sc. degrees in Electrical Engineering from the University of Split, Croatia, in 1995 and 1998, respectively. He undertook an internship with the Mathematical Research Centre at Bell Labs in 2001. From 2005 to 2014, he was a visiting professor at the University of Split, Croatia. From 2014 to 2016, he was an affiliated lecturer at the Statistical Laboratory, University of Cambridge.
Research
His research interests include data science, machine learning, artificial intelligence, game theory, multi-agent systems and information networks. He has made contributions to the theory and the design of computation platforms for processing large-scale data.
He received several prizes for his work. In 2010, he was awarded the ACM SIGMETRICS Rising Star Researcher Award, and in 2005, the ERCIM Cor Baayen Award. He received the IEEE IWQoS 2007 Best Student Paper Award (with Shao Liu and Dinan Gunawardena), the IEEE INFOCOM 2005 Best Paper Award (with Jean-Yves Le Boudec), the ACM SIGMETRICS 2005 Best Paper Award (with Laurent Massoulie) and the ITC 2001 Best Student Paper Award (with Jean-Yves Le Boudec).
Vojnovic authored the book Contest Theory: Incentive Mechanisms and Ranking Methods.
References
Computer scientists
Croatian engineers
Living people
Academics of the London School of Economics
1971 births | Milan Vojnovic | Technology | 362 |
32,323,480 | https://en.wikipedia.org/wiki/C19H22N2O2 | {{DISPLAYTITLE:C19H22N2O2}}
The molecular formula C19H22N2O2 may refer to:
5-MeO-T-NBOMe
Wieland-Gumlich aldehyde | C19H22N2O2 | Chemistry | 51 |
51,796,334 | https://en.wikipedia.org/wiki/Ocean%20data%20acquisition%20system | An ocean data acquisition system (ODAS) is a set of instruments deployed at sea to collect as much meteorological and oceanographic data as possible. With their sensors, these systems deliver data both on the state of the ocean itself and the surrounding lower atmosphere. The use of microelectronics and technologies with efficient energy consumption allows to increase the types and numbers of sensor deployed on a single device.
Definition
According to Intergovernmental Oceanographic Commission and World Meteorological Organization (WMO), "ODAS means a structure, platform, installation, buoy, or other device, not being a ship, together with its appurtenant equipment, deployed at sea essentially for the purpose of collecting, storing or transmitting samples or data relating to the marine environment or the atmosphere or the uses thereof."
Use
Each hour, the data gathered by the system is transferred to the WMO's Global Telecommunications System by a geostationary satellite after having gone through a number of quality checks. Real-time data with information on the maritime environment can then be used for forecasts of physical states like weather, ocean currents or wave conditions which, in turn, may serve to warn seafarers of unfavourable conditions in the area.
ODAS types
ODAS can be mounted on the following structures:
Lighthouses
Lightvessels
Towers
Offshore platforms
Buoys
ODAS buoys are not navigational aids but have been included into the IALA Maritime Buoyage System. The structures have a fixed geographical position.
Data
Data gathered by an ODAS may include the following parameters:
Air temperature
Atmospheric pressure at sea level
Wind direction
Wind speed including gusts
Sea state
Wave height
Sea surface temperature
Disadvantages
ODAS buoys are expensive to obtain and need to be deployed by specialised vessels.
References
Oceanographic instrumentation
Meteorological instrumentation and equipment | Ocean data acquisition system | Technology,Engineering | 366 |
231,041 | https://en.wikipedia.org/wiki/Jolly%20Roger | Jolly Roger is the traditional English name for the ensign flown to identify a pirate ship preceding or during an attack, during the early 18th century (the latter part of the Golden Age of Piracy). The vast majority of such flags flew the motif of a human skull, or “Death's Head”, often accompanied by other elements, on a black field, sometimes called the "Death's Head flag" or just the "black flag".
The flag most commonly identified as the Jolly Roger todaythe skull and crossbones symbol on a black flagwas used during the 1710s by a number of pirate captains, including Black Sam Bellamy, Edward England, and John Taylor. It became the most commonly used pirate flag during the 1720s, although other designs were also in use.
Etymology
Use of the term Jolly Roger in reference to pirate flags goes back to at least Charles Johnson's A General History of the Pyrates, published in Britain in 1724 and in fact has no connection to the given name Roger.
Johnson specifically cites two pirates as having named their flag "Jolly Roger": Bartholomew Roberts in June 1721 and Francis Spriggs in December 1723. While Spriggs and Roberts used the same name for their flags, their flag designs were very different, suggesting that already "Jolly Roger" was a generic term for black pirate flags rather than a name for any single specific design. Neither Spriggs' nor Roberts' Jolly Roger consisted of a skull and crossbones.
Richard Hawkins, who was captured by pirates in 1724, reported that the pirates had a black flag bearing the figure of a skeleton stabbing a heart with a spear, which they named "Jolly Roger". This description closely resembles the flags of a number of Golden Age pirates.
It is sometimes claimed that the term derives from "Joli Rouge" ("Pretty Red") in reference to a red flag used by French privateers. This is sometimes attributed to red blood, symbolizing violent pirates, ready to kill.
An early reference to "Old Roger" (a humorous or familiar name for the devil, or death) is found in a news report in the Weekly Journal or British Gazetteer (London, Saturday, 19 October 1723; Issue LVII, p. 2, col. 1):
“Parts of the West-Indies. Rhode-Island, July 26. This Day, 26 of the Pirates taken by his Majesty Ship the Greyhound, Captain Solgard, were executed here. Some of them delivered what they had to say in writing, and most of them said something at the Place of Execution, advising all People, young ones especially, to take warning by their unhappy Fate, and to avoid the crimes that brought them to it. Their black flag, under which they had committed abundance of Pyracies and Murders, was affix'd to one Corner of the Gallows. It had in it the Portraiture of Death, with an Hour-Glass in one Hand, and a Dart in the other, striking into a Heart, and three Drops of Blood delineated as falling from it. This Flag they called Old Roger, and us'd to say, They would live and die under it.”
History
The first recorded uses of the skull-and-crossbones symbol on naval flags date to the 17th century. It possibly originated among the Barbary pirates of the period, which would connect the black colour of the Jolly Roger to the Muslim Black Standard (black flag). But an early reference to Muslim corsairs flying a skull symbol, in the context of a 1625 slave raid on Cornwall, explicitly refers to the symbols being shown on a green flag.
There are mentions of English privateer Francis Drake flying a black flag as early as 1585, but the historicity of this tradition has been called into question. Contemporary accounts show Peter Easton using a plain black flag in 1612; a plain black flag was also used by Captain Martel's pirates in 1716, Charles Vane, and Richard Worley in 1718, and Howell Davis in 1719.
An early record of the skull-and-crossbones design being used on a (red) flag by pirates is found in a 6 December 1687 entry in a log book held by the . The entry describes pirates using the flag, not on a ship but on land.
During the 17th and 18th centuries, British privateers were required to fly a specific flag, the 1606 Union Jack with a white crest in the middle, to distinguish them from Royal Navy vessels. Before this time, British privateers, such as Sir Henry Morgan, sailed under the Red Ensign.
An early use of a black flag with skull, crossbones, and hourglass is attributed to pirate captain Emanuel Wynn in 1700, according to a wide variety of secondary sources. Reportedly, these secondary sources are based on the account of Captain John Cranby of HMS Poole and are verified at the London Public Record Office.
With the end of the War of the Spanish Succession in 1714, many privateers turned to piracy. They still used red and black flags, but now they decorated them with their own designs. Edward England, for example, flew three different flags: from his mainmast the black flag depicted above; from his foremast a red version of the same; and from his ensign staff the Red Ensign. Just as variations on the Jolly Roger design existed, red flags sometimes incorporated yellow stripes or images symbolic of death. Coloured pennants and ribbons could also be used alongside flags.
Marcus Rediker (1987) claims that most pirates active between 1716 and 1726 were part of one of two large interconnected groups sharing many similarities in organisation. He states that this accounts for the "comparatively rapid adoption of the piratical black flag among a group of men operating across thousands of miles of ocean", suggesting that the skull-and-crossbone design became standardized at about the same time as the term Jolly Roger was adopted as its name. By 1730, the diversity of symbols in prior use had been mostly replaced by the standard design.
Use in practice
Pirates did not fly the Jolly Roger at all times. The flag was intended as communication of the pirates' identity, which gave target ships an opportunity to decide to surrender without a fight. For example, in June 1720, when Bartholomew Roberts sailed into the harbour at Trepassey, Newfoundland with black flags flying, the crews of all 22 vessels in the harbour abandoned their ships in panic.
Black and red flag
It is claimed that the Jolly Roger was part of a flag signal combination, comprising a "black flag", i.e. the Jolly Roger, and a "red flag", often called a bloody flag.
The "black flag" signaled that "quarter" would be given if the target surrendered their cargo/valuables, meaning that all enemies will be guaranteed mercy after surrender or capture.
The "red flag" signaled that "no quarter" would be given and the target's cargo/valuables taken by force, meaning that no mercy will be shown and no life will be spared in an attack.
When closing on a target ship, the pirate ship would normally fly a false flag or no colours until they had their prey within firing range. Like other vessels, pirate ships usually stocked a variety of flags for various purposes.
When the pirates' intended victim was within range, the black flag would be raised, often simultaneously with a warning shot, communicating the pirates' identity to the target ship in order to persuade them to surrender without a fight. Surrendering without a fight meant that they would cooperate with the pirate's demands and allow them to rifle through their cargo, which was sometimes rewarded with some cargo being left alone. To signal "yes", the victim ship would have to take down their own flag, in naval terminology called "striking their flag".
Followed by warning shots, if the enemy did not strike their own flag to signal surrender, the pirates would raise the red flag, which would signal that the cargo would be taken by force and that "no quarter would be given" to prisoners. If the pirates had several ships, the raising of the bloody flag could also act as the signal "to attack" for the rest of the ships. The pirate captain Jean Thomas Dulaien would wait for the enemy to fire three or more cannon shots after raising the red flag before giving the order to attack with no quarter given.
An early claim of the black and red flag-combo was made in the mid-18th century by Richard Hawkins, however, the cited content may simply relate to different pirate captains, their ships, their chosen flag and particular operating practices. The bloody flag was already an established naval flag and was not unique to piracy.
Function in practice
In view of these models, it was important for a prey ship to know that its assailant was a pirate, and not a privateer or government vessel, as the latter two generally had to abide by a rule that if a crew resisted, but then surrendered, it could not be executed:
An angry pirate therefore posed a greater danger to merchant ships than an angry Spanish coast guard or privateer vessel. Because of this, although, like pirate ships, Spanish coast guard vessels and privateers were almost always stronger than the merchant ships they attacked, merchant ships may have been more willing to attempt resisting these "legitimate" attackers than their piratical counterparts. To achieve their goal of taking prizes without a costly fight, it was therefore important for pirates to distinguish themselves from these other ships also taking prizes on the seas.
Flying a Jolly Roger was a reliable way of proving oneself a pirate. Just possessing or using a Jolly Roger was considered proof that one was a criminal pirate rather than something more legitimate; only a pirate would dare fly the Jolly Roger, as he was already under threat of execution.
Design
Before 1700, pirates flew a plain black flag together with the red (“bloody”) flag, the use of emblems first taking the scene in the 18th century.
Jolly Roger variations possibly existed as a type of personal calling card to be associated with a certain pirate crew's reputation and thus make enemies surrender more easily, however, this is not mentioned by period sources. Flag motifs could often not be made out at longer ranges, thus, flag details was more likely an internal mark of identity for the crew. Historically, most pirates reused the same designs as their peers, possibly to partake in the reputation of others, eventually leading to designs such as the skull and crossbones becoming the norm.
Pirates sometimes used a national flag to symbolize their nationality or their allegiance to a nation.
Common elements
Key elements commonly found on a Jolly Roger flag typically include (some rarer than others):
Skull and crossbones – The skull, historically called "death's head" (compare ), represents death and danger, emphasizing the pirates' ruthless and deadly reputation. The crossbones are often positioned behind or beneath the skull and create an "X" shape. They symbolize crossed swords or bones, signifying violence and conflict
Human skeleton – the period depiction of the personification of death, sometimes carrying out symbolic gestures of suffering and death, such as stabbing a heart with a spear, wielding weapons and even signal instruments
Hourglass – symbolizing that the life of the attacked is running out
Bundle of arrows – an older regal or state symbol alluding to the proverb that arrows can be easily broken one by one but are unbreakable if tied together, however, in the case of the Jolly Roger, more likely to symbolize implements of death
Sword – symbolizing implements of death
Sword arm – symbolizing implements of death, a common naval motif outside piracy (see the Dutch Bloody flag)
Pistol – symbolizing implements of death
Cannon – symbolizing implements of death
Powder horn or signal horn – symbolizing implements of death
Historical designs
All illustrations presented here are merely artistic interpretations based on surviving descriptions and do not faithfully represent actual flags.
Black flags
Bloody flags
Blue flags
Green flags
Striped flags
White flags
National flags
Modern military use
By British submarines
Following the introduction of submarines in several navies circa 1900, Admiral Sir Arthur Wilson, the First Sea Lord of the British Royal Navy, stated that submarines were "underhanded, unfair, and damned un-English", and that he would convince the British Admiralty to have the crews of enemy submarines captured during wartime hanged as pirates.
In September 1914, the British submarine successfully torpedoed the German cruiser SMS Hela. Remembering Wilson's statements, commanding officer Max Horton instructed his submariners to manufacture a Jolly Roger, which was flown from the submarine as she entered port. Each successful patrol saw Horton's submarine fly an additional Jolly Roger until there was no more room for flags, at which point Horton had a large Jolly Roger manufactured, onto which symbols indicating E9s achievements were sewn. A small number of other submarines adopted the practice: flew a red flag with the skull and crossbones on return from a foray into the Dardanelles in June 1915, and the first known photograph of the practice was taken in July 1916 aboard .
The practice restarted during World War II. In October 1940, following a successful patrol by , during which she sank the Italian destroyer Palestro, the submarine returned to Alexandria, but was ordered to remain outside the boom net until the motorboat assigned to the leader of the 1st Submarine Flotilla had come alongside. The flotilla leader wanted to recognise the boat's achievement, so had a Jolly Roger made and delivered to Osiris. After this, the commanders of submarine flotillas began to hand out the flags to successful submarines. Although some sources claim that all British submarines used the flag, the practice was not taken up by those submarine commanders who saw it as boastful and potentially inaccurate, as sinkings could not always be confirmed. During the war, British submarines were entitled to fly the Jolly Roger on the day of their return from a successful patrol: it would be hoisted as the boat passed the boom net, and remain raised until sunset.
Symbols on the flag indicated the history of the submarine, and it was the responsibility of the boat's personnel to keep the flag updated. The Royal Navy Submarine Museum (which, as of 2004, possessed fifteen Jolly Rogers) recognises 20 unique symbols. A bar denotes the torpedoing of a ship: red bars indicated warships, white bars represented merchant vessels, and black bars with a white "U" stood for U-boats. A dagger indicated a 'cloak and dagger' operation: typically the delivery or recovery of shore parties from enemy territory. Stars (sometimes surrounding crossed cannon) stood for occasions where the deck gun was fired. Minelaying operations were shown by the silhouette of a sea mine: a number inside the mine indicated how many such missions. A lighthouse or torch symbolised the boat's use as a navigational marker for an invasion force; the latter more particularly associated with Operation Torch. Rescue of personnel from downed aircraft or sunken ships was marked by a lifebuoy. Unique symbols are used to denote one-off incidents: for example, the Jolly Roger of included a can-opener, referencing an incident where an Italian destroyer attempted to ram the submarine, but ended up worse off because of damage to the destroyer's hull by the submarine's hydroplanes, while added a stork and baby when the boat's commander became a father while on patrol. Flying the Jolly Roger continued in the late 20th century and on into the 21st. raised the flag decorated with the silhouette of a cruiser to recognise her successful attack on the Argentine cruiser ARA General Belgrano during the Falklands War. Several submarines returning from missions where Tomahawk cruise missiles were fired fly Jolly Rogers with tomahawk axes depicted, with crossed tomahawks indicating an unspecified number of firings, or individual axes for each successful launch. The Jolly Roger has been adopted as the logo of the Royal Navy Submarine Service.
By other units
The practice, while commonly associated with British submarines, is not restricted to them. During World War II, Allied submariners working with Royal Navy fleets adopted the process from their British counterparts. While operating in the Mediterranean, the Polish submarines ORP Sokół and ORP Dzik were presented with Jolly Rogers by General Władysław Sikorski, and continued to update them during the war. At least one British surface ship recorded their U-boat kills through silhouettes on a Jolly Roger. The Australian submarine flew the Jolly Roger in 1980, following her successful participation in the Kangaroo 3 wargame as an opposing submarine: the flag bore the silhouettes of the seven surface ships involved, as during the exercise, Onslow had successfully 'sunk' all seven.
During the Vietnam war an urgent airfield was needed at Quảng Trị by the United States forces. U.S. Seabee Battalions 1, 3, 4, 7, 11, 74, 121, and 133 all sent detachments of men and equipment to get the job done. Construction of the airfield necessitated the removal of 11,000 graves. Those detachments dubbed themselves the Ghost Battalion and chose the Jolly Roger for the Battalion's colors.
The Kuperjanov Infantry Battalion, part of the Estonian Land Forces, uses the Jolly Roger as its insignia.
Three distinct U.S. Naval Aviation squadrons have used the name and insignia of the Jolly Roger: VF-17/VF-5B/VF-61, VF-84, and VF-103, since redesignated as VFA-103. While these are distinctly different squadrons that have no lineal linkage, they all share the same Jolly Roger name, the skull and crossbones insignia and traditions.
At least twice in 2017, the USS Jimmy Carter, an American attack submarine modified to support special forces operations, returned to its home port flying a Jolly Roger. The flag was traditionally an indicative of a successful mission.
The three American destroyers named USS Kidd have all flown the Jolly Roger; they were named for US Navy Rear Admiral Isaac C. Kidd, not for William Kidd.
The Jolly Roger is also commonly used by private PMC contractors, in form of patches velcroed on uniforms and tactical jackets.
In popular culture
The Jolly Roger flag became a cliché of pirate fiction in the 19th century.
The "Golden Age of Piracy" ended by the mid-18th century, and piracy was widely suppressed by the 1800s, although the problem of Barbary pirates persisted until the French conquest of Algeria in 1830.
By the Victorian era, the pirate threat had receded enough for it to become a topos of boyish adventure fiction, notably influenced by Robert Louis Stevenson's adventure novel Treasure Island (1883). Gilbert and Sullivan's comic opera The Pirates of Penzance (which debuted on 31 December 1879) introduced pirates as comedic characters, and since the later 20th century, pirates sporting the Jolly Roger flag were often depicted as cartoonish or silly characters. J.M. Barrie also used it as the name of Captain Hook's pirate ship in Peter and Wendy (1904 play and 1911 novel); it was thus used in most adaptations of the character, including ABC's television series Once Upon a Time (2011–2018). Additionally, the Jolly Roger is depicted in Eiichiro Oda's manga One Piece, in which the pirate crews in the series have different designs that reflects the appearance of the captain (Straw Hat Pirates for example, the protagonist crew, having the classic skull with cross bones wearing a straw hat like the main character, Monkey D. Luffy) or a personal theme of the crew (Black Cat Pirates for example, one of the antagonist crews, having the head of a black cat with cross bones).
In film and television
In the film The Island (1980), the Jolly Roger is a skull with a red dot and crossbones with an hourglass on the bottom. In Disney's Pirates of the Caribbean, the Black Pearl flies a flag of skull over two crossed swords. In Black Sails, the Jolly Roger is shown at the very end as Jack Rackham's new flag.
In music
Adam and the Ants' album Kings of the Wild Frontier (1980) includes the song, "Jolly Roger".
Kenny Chesney's single "Pirate Flag" is on his fourteenth studio album Life on a Rock (2013).
The cover of indie rock band Half Man Half Biscuit's 2005 album Achtung Bono shows a stylised Jolly Roger, featuring a grinning skull adorned with sunglasses and a halo.
The cover of Iron Maiden's album A Matter of Life and Death (2006) includes a version of a Jolly Roger depicting a helmeted Eddie and two assault rifles instead of bones, hanging from a tank.
On the cover of Michael Jackson's album Dangerous (1991), the Jolly Roger can be seen on the left side with the alteration of a skull over two swords.
The re-issued version of the Megadeth album, Killing Is My Business... and Business Is Good! (1985), shows a stylized Vic Rattlehead skull on top of crossed swords and crossed bones. This was based on Mustaine's original drawing for the cover which the band did not have enough money to produce at the time.
The "pirate" German metal band Running Wild often references the Jolly Roger and other pirate related themes in their music. Their third album is named Under Jolly Roger.
Another "pirate" metal band Alestorm also uses Jolly Roger and other pirate related themes in their music.
The Pirates, a spinoff of the band Johnny Kidd & the Pirates, released an album called Out of their Skulls featuring a skull with crossed guitars below it.
British DJ Eddie Richards released the acid house hit "Acid Man" in 1988, under a Jolly Roger alias.
In sports
A number of sports teams have been known to use variations of the Jolly Roger.
The supporters of FC St. Pauli, a sports club from Hamburg, Germany best known for its association football team, adopted a variation of Richard Worley's flag as their own emblem. The club later bought the rights to the design and made it an official team logo.
The South African Football Association soccer team Orlando Pirates also has the classic Jolly Roger as their logo. Central Coast United FC in Australia use the Jolly Roger as their club crest and their active supporters are known as the Graveyard.
The short-lived Pirate Yacht Club, based in Bridlington, Yorkshire, used a red burgee defaced with a black skull and crossbones. A black skull and crossbones features on the burgee of Penzance Sailing Club, Cornwall.
"Raise the Jolly Roger!" is used in a statement by the Major League Baseball's team Pittsburgh Pirates announcer Greg Brown when the Pirates win a game. Fans of the team are known to bring Jolly Roger flags and wave them during the ballgames. The Pirates have also used versions of a skull and crossbones for their logo, with crossed bats in place of swords or bones.
The National Football League's Las Vegas Raiders' use a variation of the Jolly Roger for their logo, which depicts a head with facial features, wearing an eye patch and a helmet, and crossed swords behind the helmet.
Also in the NFL, the Tampa Bay Buccaneers' use a version of Calico Jack's flag, with a carnelian red background instead of black, and an American football positioned over the intersection of two crossed swords.
The Milwaukee Admirals of the American Hockey League have used a series of pirate Death's heads as their logo. Their current version wears a John Paul Jones-style bicorne hat emblazoned with an "A" spelled out in bones.
All these variations are seen as the logos of sporting teams in Scotland:
The Braehead Paisley Pirates/Paisley Pirates of the Scottish National League and The Paisley Buccaneers and Riversdale Pirates of the Scottish Recreational Ice Hockey Conference
The East Kilbride Pirates American football team in BAFA Division 1
The Edinburgh Buccaneers basketball club of the Scottish Men's National League
The Jolly Roger is the popular icon of all University College Cork (Ireland) sports teams.
The athletic teams of East Carolina University used a stylized Jolly Roger as one of their logos. This particular variation includes an earringed and eyepatch-wearing skull donning a tricorn of purple and gold (the school's colors) emblazoned over two crossbones. This logo appears on the helmets of the school's football team, and an elaborate pre-game ritual takes place prior to each home contest wherein a flag bearing the university's Jolly Roger logo is raised on a special flagpole located behind the west end zone prior to the opening kickoff. Immediately prior to the start of the fourth quarter, the normal (black) Jolly Roger is lowered and replaced with a flag bearing the ECU Jolly Roger on a red background, indicating that the Pirates will grant their opponents "no quarter".
The Blackshirts, the starting defensive unit players for the Nebraska Cornhuskers football team, are represented by a Jolly Roger, somewhat similar to Richard Worley's flag but with the skull encased in the team's football helmet. Additionally, the players and fans often celebrate by "throwing the bones", where they cross the forearms in front of the chest in an 'X' imitating the logo, and the student section at Memorial Stadium, Lincoln is known as the 'Boneyard', where the logo is often displayed on banners, signs, and flags in an act of intimidation.
Other uses
The early development team of the Apple Macintosh used a pirate flag to portray a "rebellious" spirit.
Before changing to a stylized "P", Sweden's Pirate Party used the Jolly Roger as its symbol, which is still used extensively in the Pirate movement. The Piratbyrån and its online database, The Pirate Bay also use either the skull and crossbones symbol, or derivatives of it, such as the logo of Home Taping Is Killing Music.
The flag of the Sea Shepherd Conservation Society is modeled to look like a classic Jolly Roger, with some alterations. The flag depicts a whale and a dolphin on the skull's forehead, and the crossed long-bones are replaced with a crossed trident and a shepherd's crook.
Unicode uses a sequence of and to display this flag.
See also
Anarchist flag
Flags of the Makhnovshchina
Kronstadt rebellion & Soviet Republic of Naissaar (Flag of rebelling anarchist sailors being black with white skull and crossbones)
Bloody flag
Flag of Blackbeard
Maritime flag
Ossuary
Pesthörnchen (CCC)
Totenkopf
VF-61, VF-84 and VF-103, US Navy fighter squadrons nicknamed "Jolly Rogers"
References
Explanatory notes
Citations
Bibliography
Books
Journal and news articles
Websites
External links
Cross symbols
Maritime flags
Pictograms
Pirate customs and traditions
Skulls in art
Memento mori | Jolly Roger | Mathematics | 5,459 |
174,850 | https://en.wikipedia.org/wiki/Andalusite | Andalusite is an aluminium nesosilicate mineral with the chemical formula Al2SiO5. This mineral was called andalousite by Delamétherie, who thought it came from Andalusia, Spain. It soon became clear that it was a locality error, and that the specimens studied were actually from El Cardoso de la Sierra, in the Spanish province of Guadalajara, not Andalusia.
Andalusite is trimorphic with kyanite and sillimanite, being the lower pressure mid temperature polymorph. At higher temperatures and pressures, andalusite may convert to sillimanite. Thus, as with its other polymorphs, andalusite is an aluminosilicate index mineral, providing clues to depth and pressures involved in producing the host rock.
Varieties
The variety chiastolite commonly contains dark inclusions of carbon or clay which form a cruciform pattern when shown in cross-section. This stone was known at least from the sixteenth century, being taken to many European countries, as a souvenir, by pilgrims returning from Santiago de Compostela.
Viridine is a green variety of andalusite in which manganese 3+ substitutes for aluminium, the same change is also responsible for the colour. Kanonaite is a greenish-black mineral related to andalusite and having the approximate composition .
A clear variety found in Brazil and Sri-Lanka can be cut into a gemstone. Faceted andalusite stones give a play of red, green, and yellow colors that resembles a muted form of iridescence, although the colors are actually the result of unusually strong pleochroism.
Occurrence
Andalusite is a common metamorphic mineral which forms under low pressure and low to high temperatures. The minerals kyanite and sillimanite are polymorphs of andalusite, each occurring under different temperature-pressure regimes and are therefore rarely found together in the same rock. Because of this the three minerals are a useful tool to help identify the pressure-temperature paths of the host rock in which they are found. It is particularly associated with pelitic metamorphic rocks such as mica schist.
The world's highest concentration of andalusite is found in the Glomel mine in Côtes-d'Armor (France) which accounts for 25% of the global production of this mineral. South Africa possesses the largest portion of the world's known andalusite deposits.
Uses
Andalusite is used as a refractory in furnaces, kilns and other industrial processes.
See also
List of minerals
References
Aluminium minerals
Nesosilicates
Orthorhombic minerals
Minerals in space group 58
Industrial minerals
Gemstones | Andalusite | Physics | 569 |
5,135,097 | https://en.wikipedia.org/wiki/Rational%20R1000 | The R1000 was a workstation released in 1985 by Rational Software for the design, documentation, implementation, and maintenance of large software systems written using the Ada programming language. The R1000 featured an extensive tool set, including:
an Ada-83-compatible program design language
an integrated development environment that doubled as an operating system shell
automatic generation of design documentation
source-language debugging
interactive design-rule checking and semantic analysis
incremental compilation
configuration management and version control.
Optimizing code generators and cross-debuggers provided support for several popular application architectures.
As a successor to the R1000, Rational produced a new IDE called Rational Apex. Rational Apex took many of the features that the R1000 introduced and extended (ported) them onto commonly available workstations from Sun Microsystems and IBM.
Several R1000 units exist in museums and private collections, but, because of the classified nature of much Ada programming, these units had been wiped; efforts have been made to boot one of these systems, with little or no luck as of 2013. On 28 October 2019 the DataMuseum.dk successfully got one unit back into running condition.
References
External links
Evaluation of the Rational Environment report on analysis of the R1000 by Software Engineering Institute
Rational Announces Shipment of Apex 3.0 With Integrated Family of Products
Use of the Rational R1000 Ada development environment for an IBM based command and control system. by Charles B. Williams, 1987
Integrated development environments
Computer workstations
Ada (programming language) | Rational R1000 | Engineering | 311 |
29,797,960 | https://en.wikipedia.org/wiki/Asilomar%20International%20Conference%20on%20Climate%20Intervention%20Technologies | The Asilomar International Conference on Climate Intervention Technologies was a conference developed by Margaret Leinen of the Climate Response Fund and chaired by Michael MacCracken of the Climate Institute. The conference took place in March 2010 and the recommendations were published in November 2010. The goal was identify and minimize risks involved with climate engineering (geoengineering, or climate intervention), and was based on the 1975 Asilomar Conference on Recombinant DNA which discussed the potential biohazards and regulation of biotechnology. A group of over 150 scientist and engineers gathered together with lawyers, environmentalists and disaster relief workers in an open meeting to avoid accusations of conspiracy during this discussion. The Asilomar Conference focused exclusively on the development of risk reduction guidelines for climate intervention experiments.
Goals of the conference
Identify potential risks associated with climate intervention experiments
Propose a system to assess experiment design for potential categorical risks and suggest precautions to assure their safe conduct
Propose voluntary standards for climate intervention research for the international scientific community
Recommendations
The core rationale for pursuit of climate engineering research is to advance the collective well-being of society and the environment;
Climate engineering research is internationally planned and coordinated;
Appropriately scoped governmental oversight, public involvement, and decision-making takes place during consideration and conduct of planned activities;
Transparency and exchange of research plans, data, and findings minimize the need for environmentally disruptive experiments and maximize the learning from experiments that are conducted; and
Regular, independent evaluation and assessment of the extent of understanding and uncertainty is carried out to provide optimal information and confidence for the public and policymakers
Steering committee
Michael C. MacCracken (chair), Climate Institute, USA
Scott Barren, Columbia University, USA
Roger Barry, World Data Center for Glaciology and University of Colorado, USA
Paul Crutzen (corresponding member), Max Planck Institute, Germany, and Scripps Institution of Oceanography, USA
Steven Hamburg, Chief Scientist, Environmental Defense Fund, USA
Richard Lampitt, National Oceanography Centre and University of Southampton, UK
Diana Liverman, University of Arizona, US, and Oxford University, UK
Thomas Lovejoy, H. John Heinz III Center for Science, Economics and the Environment, USA
Gordon McBean, The University of Western Ontario, Canada
John Shepherd, National Oceanography Centre, University of Southampton, and Tyndall Centre for Climate Change Research, UK
Stephen Seidel, Pew Center on Global Climate Change, USA
Richard Somerville, Scripps Institution of Oceanography, University of California, San Diego, USA
Tom M. L. Wigley, University of Adelaide, Australia
References
Further reading
External links
Asilomar International Conference on Climate Intervention Technologies, 2010, Climate Response Fund
The Asilomar Conference Recommendations on Principles for Research into Climate Engineering Techniques. Conference Report
2010 in the environment
Climate change conferences
Climate change mitigation
Climate engineering
History of Monterey County, California
History of the Monterey Bay Area
Events in the Monterey Bay Area | Asilomar International Conference on Climate Intervention Technologies | Engineering | 589 |
27,372,985 | https://en.wikipedia.org/wiki/Mass%20action%20law%20%28electronics%29 | In electronics and semiconductor physics, the law of mass action relates the concentrations of free electrons and electron holes under thermal equilibrium. It states that, under thermal equilibrium, the product of the free electron concentration and the free hole concentration is equal to a constant square of intrinsic carrier concentration . The intrinsic carrier concentration is a function of temperature.
The equation for the mass action law for semiconductors is:
Carrier concentrations
In semiconductors, free electrons and holes are the carriers that provide conduction. For cases where the number of carriers are much less than the number of band states, the carrier concentrations can be approximated by using Boltzmann statistics, giving the results below.
Electron concentration
The free-electron concentration n can be approximated by
where
Ec is the energy of the conduction band,
EF is the energy of the Fermi level,
kB is the Boltzmann constant,
T is the absolute temperature in kelvins,
Nc is the effective density of states at the conduction band edge given by , with m*e being the electron effective mass and h being the Planck constant.
Hole concentration
The free-hole concentration p is given by a similar formula
where
EF is the energy of the Fermi level,
Ev is the energy of the valence band,
kB is the Boltzmann constant,
T is the absolute temperature in kelvins,
Nv is the effective density of states at the valence band edge given by , with m*h being the hole effective mass and h being the Planck constant.
Mass action law
Using the carrier concentration equations given above, the mass action law can be stated as
where Eg is the band gap energy given by Eg = Ec − Ev. The above equation holds true even for lightly doped extrinsic semiconductors as the product is independent of doping concentration.
See also
Law of mass action
References
External links
Doping, Carrier Concentration, Mobility, and Conductivity
Semi-conductor tutorial
Electronic engineering
Empirical laws | Mass action law (electronics) | Technology,Engineering | 392 |
2,432,911 | https://en.wikipedia.org/wiki/Mass%20flow%20sensor | A mass (air) flow sensor (MAF) is a sensor used to determine the mass flow rate of air entering a fuel-injected internal combustion engine.
The air mass information is necessary for the engine control unit (ECU) to balance and deliver the correct fuel mass to the engine. Air changes its density with temperature and pressure. In automotive applications, air density varies with the ambient temperature, altitude and the use of forced induction, which means that mass flow sensors are more appropriate than volumetric flow sensors for determining the quantity of intake air in each cylinder.
There are two common types of mass airflow sensors in use on automotive engines. These are the vane meter and the hot wire. Neither design employs technology that measures air mass directly. However, with additional sensors and inputs, an engine's ECU can determine the mass flow rate of intake air.
Both approaches are used almost exclusively on electronic fuel injection (EFI) engines. Both sensor designs output a 0.0–5.0 volt or a pulse-width modulation (PWM) signal that is proportional to the air mass flow rate, and both sensors have an intake air temperature (IAT) sensor incorporated into their housings for most post on-board diagnostics (OBDII) vehicles. Vehicles prior to 1996 could have MAF without an IAT. An example is 1994 Infiniti Q45.
When a MAF sensor is used in conjunction with an oxygen sensor, the engine's air/fuel ratio can be controlled very accurately. The MAF sensor provides the open-loop controller predicted air flow information (the measured air flow) to the ECU, and the oxygen sensor provides closed-loop feedback in order to make minor corrections to the predicted air mass. Also see manifold absolute pressure sensor (MAP sensor). Since around 2012, some MAF sensors include a humidity sensor.
Moving vane meter
The VAF (vane air flow) sensor measures the momentum of the air flow into the engine with a spring-loaded air vane (flap/door) attached to a variable resistor (potentiometer). The vane moves in proportion to the momentum of the airflow. A voltage is applied to the potentiometer and a voltage appears on the output terminal of the potentiometer proportional to the angle the vane rotates, or the movement of the vane may directly regulate the amount of fuel injected, as in the K-Jetronic system.
Many VAF sensors have an air-fuel adjustment screw, which opens or closes a small air passage on the side of the VAF sensor. This screw controls the air-fuel mixture by letting a metered amount of air flow past the air flap, thereby leaning or richening the mixture. By turning the screw clockwise the mixture is enriched and counterclockwise the mixture is leaned.
The vane moves because of the drag force of the air flow against it; it does not measure volume or mass directly. The drag force depends on air density (air density in turn depends on air temperature), air velocity and the shape of the vane, see drag equation. Some VAF sensors include an additional intake air temperature sensor (IAT sensor) to allow the engines ECU to calculate the density of the air, and the fuel delivery accordingly.
The vane meter approach has some drawbacks:
it restricts airflow which limits engine output
its moving electrical or mechanical contacts can wear
finding a suitable mounting location within a confined engine compartment is problematic
the vane has to be oriented with respect to gravity.
in some manufacturers fuel pump control was also part on the VAF internal wiring.
Hot wire sensor (MAF)
A hot wire mass airflow sensor determines the mass of air flowing into the engine's air intake system. The theory of operation of the hot wire mass airflow sensor is similar to that of the hot wire anemometer (which determines air velocity). This is achieved by heating a wire suspended in the engine's air stream, like a toaster wire, by applying a constant voltage over the wire. The wire's electrical resistance increases as the wire's temperature increases, which varies the electrical current flowing through the circuit, according to Ohm's law. When air flows past the wire, the wire cools, decreasing its resistance, which in turn allows more current to flow through the circuit, since the supply voltage is a constant. As more current flows, the wire's temperature increases until the resistance reaches equilibrium again. The current increase or decrease is proportional to the mass of air flowing past the wire. The integrated electronic circuit converts the proportional measurement into a proportional voltage which is sent to the ECU.
If air density increases due to pressure increase or temperature drop, but the air volume remains constant, the denser air will remove more heat from the wire indicating a higher mass airflow. Unlike the vane meter's paddle sensing element, the hot wire responds directly to air density. This sensor's capabilities are well suited to support the gasoline combustion process which fundamentally responds to air mass, not air volume. (See stoichiometry.)
This sensor sometimes employs a mixture screw, but this screw is fully electronic and uses a variable resistor (potentiometer) instead of an air bypass screw. The screw needs more turns to achieve the desired results. A hot wire burn-off cleaning circuit is employed on some of these sensors. A burn-off relay applies a high current through the platinum hot wire after the vehicle is turned off for a second or so, thereby burning or vaporizing any contaminants that have stuck to the platinum hot wire element.
The hot film MAF sensor works somewhat similar to the hot wire MAF sensor, but instead it usually outputs a frequency signal. This sensor uses a hot film-grid instead of a hot wire. It is commonly found in late 1980s and early 1990s fuel-injected vehicles. The output frequency is directly proportional to the air mass entering the engine. So as mass flow increases so does frequency. These sensors tend to cause intermittent problems due to internal electrical failures. The use of an oscilloscope is strongly recommended to check the output frequency of these sensors. Frequency distortion is also common when the sensor starts to fail. Many technicians in the field use a tap test with very conclusive results. Not all HFM systems output a frequency. In some cases, this sensor works by outputting a regular varying voltage signal.
A micro-bridge uses the same principles but arranged on a silicon chip.
Coldwire sensor
The GM LS engine series (as well as others) use a coldwire MAF system (produced by AC Delco) that works similarly to the hot-wire MAF system; however, it uses an additional "cold" resistor to measure the ambient air and provide a reference for the "hot" resistor element used to measure the air flow.
The mesh on the MAF is used to smooth out airflow to ensure the sensors have the best chance of a steady reading. It is not used for measuring the air flow per se. In situations where owners use oiled-gauze air filters, it is possible for excess oil to coat the MAF sensor and skew its readings. Indeed, General Motors has issued a Technical Service Bulletin, indicating problems from rough idle all the way to possible transmission damage resulting from the contaminated sensors. To clean the delicate MAF sensor components, a specific MAF sensor cleaner or electronics cleaner should be used, not carburetor or brake cleaners, which can be too aggressive chemically. Instead, the liquid phase of MAF sensor cleaners and electronics cleaners is typically based on hexanes or heptanes with little to no alcohol content and use either carbon dioxide or HFC-152a as aerosol propellants. The sensors should be gently sprayed from a careful distance to avoid physically damaging them and then allowed to thoroughly dry before reinstalling. Manufacturers claim that a simple but extremely reliable test to ensure correct functionality is to tap the unit with the back of a screwdriver while the car is running, and if this causes any changes in the output frequency then the unit should be discarded and an OEM replacement installed.
Kármán vortex sensor
A Kármán vortex sensor works by disrupting the air stream with a perpendicular bow. Providing that the incoming flow is laminar, the wake consists of an oscillatory pattern of Kármán vortices. The frequency of the resulting pattern is proportional to the air velocity.
These vortices can either be read directly as a pressure pulse against a sensor, or they can be made to collide with a mirror which will then interrupt or transmit a reflected light beam to generate the pulses in response to the vortices. The first type can only be used in pull-thru air (prior to a turbo- or supercharger), while the second type could theoretically be used push- or pull-thru air (before or after a forced induction application like the previously mentioned super- or turbocharger). Instead of outputting a constant voltage modified by a resistance factor, this type of MAF outputs a frequency which must then be interpreted by the ECU. This type of MAF can be found on all DSMs (Mitsubishi Eclipse, Eagle Talon, Plymouth Laser), many Mitsubishis, some Toyotas and Lexus, and some BMWs, among others.
Membrane sensor
An emerging technology utilizes a very thin electronic membrane placed in the air stream. The membrane has a thin film temperature sensor printed on the upstream side, and one on the downstream side. A heater is integrated in the center of the membrane which maintains a constant temperature similar to the hot-wire approach. Without any airflow, the temperature profile across the membrane is uniform. When air flows across the membrane, the upstream side cools differently from the downstream side. The difference between the upstream and downstream temperature indicates the mass airflow. The thermal membrane sensor is also capable of measuring flow in both directions, which sometimes occur in pulsating situations. Technological progress allows this kind of sensor to be manufactured on the microscopic scale as microsensors using microelectromechanical systems technology. Such a microsensor reaches a significantly higher speed and sensitivity compared with macroscopic approaches. See also MEMS sensor generations.
Laminar flow elements
Laminar flow elements measure the volumetric flow of gases directly. They operate on the principle that, given laminar flow, the pressure difference across a pipe is linearly proportional to the flow rate. Laminar flow conditions are present in a gas when the Reynolds number of the gas is below the critical figure. The viscosity of the fluid must be compensated for in the result. Laminar flow elements are usually constructed from a large number of parallel pipes to achieve the required flow rating.
See also
List of auto parts
List of sensors
Manifold absolute pressure (MAP)
References
Engine sensors
Flow meters
Gas technologies
Mass | Mass flow sensor | Physics,Chemistry,Mathematics,Technology,Engineering | 2,221 |
1,188,599 | https://en.wikipedia.org/wiki/IS-641 | TIA/EIA standard IS-641 is a speech coding standard used in some computer and telecommunications networks in the U.S.A. The main usage was in the U.S. TDMA networks defined by IS-136. The bit rate of the speech codec is 7.4 kbit/s. This codec is the same as the 7.4 kbit/s mode in the AMR speech codec. The standard has been superseded by TIA/EIA-136-410.
Speech codecs
Mobile telecommunications standards | IS-641 | Technology | 112 |
36,899,683 | https://en.wikipedia.org/wiki/Developer%21%20Developer%21%20Developer%21 | Developer! Developer! Developer!, more commonly known as DDD, is a series of community conferences aimed at software developers.
History
DDD conferences started in 2005, as a community conference organised by software developers for software developers. The first was held at Microsoft's TVP campus in Reading, United Kingdom. There have been 10 DDD conference held in this location, as well as a number of regional conferences held in Belfast, Bristol, Wales, Cambridge, Dublin, Dundee, Edinburgh, Galway, Glasgow, Leeds, Sunderland, Taunton and Bradford. In Australia: Perth, Sydney, Melbourne, Brisbane and Adelaide. In South Korea: Seoul.
The original DDD event in Reading has frequently sold out on the day the tickets become available. The record is 350 tickets selling out in 13 minutes.
Key Values
DDD was set up with a number of key elements in mind.
It is free
It is on a Saturday
An open submissions process
A democratically chosen agenda
The Australian DDD events do have a nominal ticket price, primarily to minimise the number of people who register to attend but don't show up. Subsidised tickets are available for those who can't afford this.
References
External links
Main DDD Website
DDD North Website
DDD SouthWest Website
DDD East Anglia Website
DDD Scotland Website
DDD Brisbane Website
DDD Melbourne Website
DDD Perth Website
DDD Sydney Website
DDD Wales
DDD East Midlands (first event scheduled for 2019)
DDD Brisbane Website
DDD Adelaide Website
DDD Seoul Website
Software developer communities
Computer conferences
Microsoft conferences | Developer! Developer! Developer! | Technology | 314 |
11,124,204 | https://en.wikipedia.org/wiki/NGC%20250 | NGC 250 is a lenticular galaxy in the constellation
Pisces.
References
External links
0250
02765
0487
2765
Lenticular galaxies
18851110
Pisces (constellation) | NGC 250 | Astronomy | 41 |
16,392,407 | https://en.wikipedia.org/wiki/Energy%20Victory | Energy Victory: Winning the War on Terror by Breaking Free of Oil is a 2007 book by Robert Zubrin. Zubrin's central argument is that the decisive front in the War on Terror is America's struggle for energy independence. He outlines the manner in which Islamic extremism has been financed by oil revenues, the technological feasibility of ethanol-fueled vehicles as well as the economic and agricultural imperatives for ethanol production, and the environmental implications of his plan.
Synopsis
Problem
Zubrin contends that OPEC nations, particularly Saudi Arabia, have used their enormous oil wealth to fund Islamic extremism; in effect, the US is financing both sides of the War on Terror. They have been able to do this through colluding to keep oil prices high. Due to its dependence on their oil, the United States (and the rest of the world) is powerless to do anything about this.
Flex-fuel mandate
The key to winning the war on terror, therefore, is to create a substitute for oil. Zubrin argues that a mandate that all new cars sold in the United States be flex-fueled (FFV, for Flex-Fuel Vehicle, able to run on gasoline, ethanol or methanol, or any combination thereof) would very quickly make such vehicles the world standard, as occurred in the early 1980s with the introduction of catalytic converters. As a result, consumers would demand ethanol- and methanol-blended fuels due to their price competitiveness with gasoline, which would in turn prompt gas stations to instal biofuel pumps. Under such a situation, competition would drive oil prices down. Zubrin argues that biofuels should be subsidized in order to keep their price advantage over gasoline, as it is the only way to cripple OPEC.
Some have argued that a switch to electric cars would be more beneficial. While this may be a longer-term solution, a switch to biofuel can be achieved in a few years (as in the case of Brazil). Additionally, existing cars (including hybrids) can be retrofitted with flex-fuel capability for "between $100 and $500".
A switch to biofuel would have the additional benefit that it is potentially a carbon-neutral fuel.
Development argument
Ethanol is produced primarily via the fermentation of corn or sugar cane (or indeed any other glucose-rich crop). Methanol can be produced from any plant matter. As both of these products can easily be produced in developing countries, Zubrin contends that the resultant expanding market for farm produce would be greatly beneficial for third-world farmers. There would be no need for western nations to subsidize their own farmers, as third-world produce could be absorbed into the larger market without causing a price-crash that would bankrupt western farmers.
Tariff elimination
Anne Korin, of The Institute for the Analysis of Global Security, has developed this concept further, adding to Zubrin's mandate the necessity to eliminate ethanol and sugar import tariffs in the United States for it to succeed.
Reception
Gal Luft, writing for the Institute for the Analysis of Global Security, called Energy Victory "one of the best books written on our oil dependence problem".
Zubrin presented the arguments from Energy Victory at a series of "go green" lectures sponsored by the Advanced Planning and Partnership Office and hosted by NASA, in January 2008.
See also
Energy security
Hydrogen economy
List of books about energy issues
Methanol economy
New Manhattan Project for Energy Independence
Open Fuel Standard Act of 2011
Pickens Plan
Wahhabism
References
External links
, presenting an outline of the book
Energy Victory website
MSNBC - Is alcohol the energy answer?
Robert Zubrin - The Hydrogen Hoax
The Institute for the Analysis of Global Security - Endorses Robert Zubrin's Flex-fuel Mandate and further develops the concept & evidence supporting it.
2007 non-fiction books
2007 in the environment
American non-fiction books
Energy policy
Ethanol fuel
Peak oil books
Political plans in the United States
Renewable energy in the United States
Books by Robert Zubrin
Environmental non-fiction books | Energy Victory | Environmental_science | 835 |
16,981,677 | https://en.wikipedia.org/wiki/Journal%20of%20Cell%20Science | The Journal of Cell Science (formerly the Quarterly Journal of Microscopical Science) is a peer-reviewed scientific journal in the field of cell biology. The journal is published by The Company of Biologists. The journal is partnered with Publons, is part of the Review Commons initiative and has two-way integration with bioRxiv. Journal of Cell Science is a hybrid journal and publishes 24 issues a year. Content over 6 months old is free to read.
History
Foundation and early years
The journal was established in 1853 as the Quarterly Journal of Microscopical Science (Q. J. Microsc. Sci., ). The founding editors were Edwin Lankester and George Busk. The publisher of the early issues was Samuel Highley of Fleet Street, London, with John Churchill and Sons (later J. & A. Churchill) taking over from 1856. The journal's original aims, as described in a preface to the first issue, were not limited to biology, but encompassed all branches of science related to the microscope:
Contributors to the first issue include Thomas Henry Huxley, Joseph Lister, William Crawford Williamson, and George Shadbolt. The contents of the early issues are diverse, and include original research articles, translations of papers published in other languages, transactions of the meetings of the Microscopical Society of London (later the Royal Microscopical Society), and book reviews. The journal also published short notes and memoranda, aimed "to gather up fragments of information, which singly might appear to be useless but together are of great importance to science"; the editors encouraged non-specialist submissions to this section, considering that "there are few possessors of a Microscope who have not met with some stray fact or facts which, published in this way, may not lead to important results." The editors also intended "to relieve the graver and more strictly scientific matter of the Journal by lighter contributions, such as will be found useful to the beginner, not uninteresting to the advanced observer, and of interest perhaps to the general reader."
Lankester and Busk co-edited the journal until the end of 1868. Lankester continued to edit the journal with his son, Ray Lankester until the end of 1871.
Under Ray Lankester and Edwin Goodrich
After Edwin Lankester's retirement, Ray Lankester remained an editor, with co-editors including E. Klein, William Archer, Joseph Frank Payne, and W. T. Thiselton Dyer. From 1878 until 1920, he served as the sole editor, amassing a total of over fifty years as an editor of the journal. The journal flourished under his guidance, becoming one of the leading British science journals. His successor, Edwin Stephen Goodrich, served as editor for twenty-five years, from 1920 until his death in 1946. Oxford University Press took over as publishers in 1920.
The Company of Biologists and relaunch
In 1946 or 1947, George Parker Bidder, then the owner, gave the journal to The Company of Biologists, a company he had founded in 1925 in a successful bid to rescue the failing British Journal of Experimental Biology. Initially, Oxford University Press remained the publishers on behalf of the Company of Biologists, but production was later transferred to Cambridge University Press. In 1952, The Company of Biologists became a registered charity, and full editorial control passed to the journal's editor-in-chief.
From 1946, the journal was edited jointly by Carl Pantin, an experimental zoologist and physiologist, and John Baker, a cytologist. Under the latter's influence, the journal accepted a growing number of papers in the relatively new discipline of cytology, now usually termed cell biology. After Pantin's retirement in 1960, the scope of the journal was refocused on the field of cytology, which the editors defined as "Everything that relates directly to the structure, chemical composition, physical nature, and functions of animal and plant cells, or to the techniques that are used in cytological investigations". Subsequent editors include H. G. Callan and A. V. Grimstone.
In 1966, the journal was redesigned and relaunched under the new title Journal of Cell Science, reflecting its altered scope. It continued to be published broadly quarterly until 1969, when the frequency increased to between six and nine issues per year. In the mid-to-late 1980s, to reduce publication lead times and compete more effectively with Cell (which had been launched in 1974), The Company of Biologists moved away from Cambridge University Press and set up its own in-house typesetting and printing for its journals, by then three in number, becoming pioneers in using disks from authors. Publication frequency also increased, at first to ten issues in 1987, then monthly between 1988 and 1995, finally becoming fortnightly in December 1996.
Issues from 1853 are available online via the journal website and HighWire Press as PDFs, with a text version additionally available from 2000. Content over 6 months old is freely available, and all articles are available to readers in developing countries via the Health InterNetwork Access to Research Initiative. Since 2004, authors have retained copyright of their material, licensing their contributions to the journal.
Scope and content
Journal of Cell Sciences publishes original research articles and reports, techniques and resources, reviews, and primers across the full range of topics in cell biology.
In addition to research papers and reviews, Journal of Cell Science includes critical commentaries and an occasional column, "Sticky Wickets", offering "controversial views of life-science research".
When appropriate, some articles are grouped into subject collections. Collection topics covered include:
Adhesion
Autophagy
Cell biology and disease
Cilia and flagella
Collective cell migration
ESCRT machinery
Establishing polarity
Exploring the nucleus
Imaging
Invadopodia and podosomes
Mechanotransduction
Microtubule dynamics
Mitochondria
Stem cells
Tools in cell biology
Ubiquitin
The journal operates on a continuous publication model. The final version of record is released online as soon as it is ready.
Abstracting and indexing
Journal of Cell Science is abstracted and/or indexed by:
BIOBASE
CAM abstracts
Cambridge Scientific Abstracts
Current Content
EMBASE
Clarivate Web of Science
Medline
Scopus
Journal of Cell Science is a signatory of the San Francisco Declaration on Research Assessment (DORA).
Journal management
Michael Way (Francis Crick Institute, UK) has been the editor-in-chief since 2012, when he took over from Fiona Watt.
References
External links
Delayed open access journals
Publications established in 1853
Molecular and cellular biology journals
Biweekly journals
English-language journals
The Company of Biologists academic journals | Journal of Cell Science | Chemistry | 1,355 |
1,701,834 | https://en.wikipedia.org/wiki/Four-current | In special and general relativity, the four-current (technically the four-current density) is the four-dimensional analogue of the current density, with units of charge per unit time per unit area. Also known as vector current, it is used in the geometric context of four-dimensional spacetime, rather than separating time from three-dimensional space. Mathematically it is a four-vector and is Lorentz covariant.
This article uses the summation convention for indices. See covariance and contravariance of vectors for background on raised and lowered indices, and raising and lowering indices on how to switch between them.
Definition
Using the Minkowski metric of metric signature , the four-current components are given by:
where:
is the speed of light;
is the volume charge density;
is the conventional current density;
The dummy index labels the spacetime dimensions.
Motion of charges in spacetime
This can also be expressed in terms of the four-velocity by the equation:
where:
is the charge density measured by an inertial observer O who sees the electric current moving at speed (the magnitude of the 3-velocity);
is “the rest charge density”, i.e., the charge density for a comoving observer (an observer moving at the speed - with respect to the inertial observer O - along with the charges).
Qualitatively, the change in charge density (charge per unit volume) is due to the contracted volume of charge due to Lorentz contraction.
Physical interpretation
Charges (free or as a distribution) at rest will appear to remain at the same spatial position for some interval of time (as long as they're stationary). When they do move, this corresponds to changes in position, therefore the charges have velocity, and the motion of charge constitutes an electric current. This means that charge density is related to time, while current density is related to space.
The four-current unifies charge density (related to electricity) and current density (related to magnetism) in one electromagnetic entity.
Continuity equation
In special relativity, the statement of charge conservation is that the Lorentz invariant divergence of J is zero:
where is the four-gradient. This is the continuity equation.
In general relativity, the continuity equation is written as:
where the semi-colon represents a covariant derivative.
Maxwell's equations
The four-current appears in two equivalent formulations of Maxwell's equations, in terms of the four-potential when the Lorenz gauge condition is fulfilled:
where is the D'Alembert operator, or the electromagnetic field tensor:
where μ0 is the permeability of free space and ∇α is the covariant derivative.
General relativity
In general relativity, the four-current is defined as the divergence of the electromagnetic displacement, defined as:
then:
Quantum field theory
The four-current density of charge is an essential component of the Lagrangian density used in quantum electrodynamics. In 1956 Semyon Gershtein and Yakov Zeldovich considered the conserved vector current (CVC) hypothesis for electroweak interactions.
See also
Four-vector
Noether's theorem
Covariant formulation of classical electromagnetism
Ricci calculus
References
Electromagnetism
Four-vectors | Four-current | Physics | 669 |
26,196,283 | https://en.wikipedia.org/wiki/Recruitment%20%28biology%29 | When discussing population dynamics, behavioral ecology, and cell biology, recruitment refers to several different biological processes. In population dynamics, recruitment is the process by which new individuals are added to a population, whether by birth and maturation or by immigration. When discussing behavioral ecology and animal communication, recruitment is communication that is intended to add members of a group to specific tasks. Finally, when discussing cell biology, recruitment is the process by which cells are selected for certain tasks.
Recruitment in population dynamics
Definition and importance
In population dynamics and community ecology, recruitment is the process by which individuals are added to a population. Successful recruitment is contingent on an individual surviving and integrating within the population; in some studies, individuals are only considered to have been recruited into a population once they've reached a certain size or life stage. Recruitment can be hard to assess due to the multitude of factors that affect it, such as predation, birth, and dispersal rates and environmental factors like temperature, precipitation, and natural disturbances. Recruitment rates in turn affect population size and demographics. High recruitment may increase a species' current and future abundance within a system, whereas low recruitment can lead to reduced current and future abundance.
Common study systems
Aquatic systems
Recruitment can be an important factor in predicting future population growth potential. For this reason, and due to their economic importance, recruitment has commonly been studied in fishery systems. While experimental work has been done in aquatic systems, dozens of papers have been published in the last few decades to model recruitment in both marine and freshwater aquatic environments.
Forest systems
Experimental studies on the effects of recruitment are numerous in forest and annual plant systems.
Recruitment in behavioral ecology
In behavioral ecology and studies of animal communication, recruitment is the process by which individuals in a social group direct other individuals to do certain tasks. This is often achieved through the use of recruitment pheromones that direct anywhere from one to several hundred individuals to important resources, like food or nesting sites. Recruitment is practiced in a wide variety of eusocial taxa, most notably in hymenoptera (the ants, bees, and wasps) and termites but also in social caterpillars, beetles, and even a species of naked mole rats (Heterocephalus glaber).
References
Ecosystems | Recruitment (biology) | Biology | 454 |
36,252,156 | https://en.wikipedia.org/wiki/Hauser%20base | Hauser bases, also called magnesium amide bases, are magnesium compounds used in organic chemistry as bases for metalation reactions. These compounds were first described by Charles R. Hauser in 1947. Compared with organolithium reagents, the magnesium compounds have more covalent, and therefore less reactive, metal-ligand bonds. Consequently, they display a higher degree of functional group tolerance and a much greater chemoselectivity. Generally, Hauser bases are used at room temperature while reactions with organolithium reagents are performed at low temperatures, commonly at −78 °C.
Structures
Hauser bases have the empirical formula R2NMgX (X = halide). The crystallize as dimers with halide bridges. Attached to Mg is amido (R2N) ligands derived from secondary amines 2,2,6,6-tetramethylpiperidine (TMP−) and HMDS−).
Amido-bridged Hauser bases exist when the amido ligand is less bulky, such as Et2N− and Ph3P=N−.
The structures of Hauser bases in solution have been investigated by diffusion-ordered NMR spectroscopy (DOSY). These studies indicate that iPr2NMgCl is subject to the Schlenk equilibrium:
iPr2NMgCl (A) (iPr2N)2Mg (B) + MgCl2
This equilibrium is temperature-dependent: heteroleptic (A) are the main species at high temperatures and homoleptic (B) dominate at lower temperatures. Dimeric species with bridging chlorides and amides are also present in the THF solution. At low temperatures, adducts of MgCl2 are present in solution.
Preparation and reactions
The Hauser bases are prepared by treating a secondary amine with a Grignard reagent:
R2NH + R′MgX → R2NMgX + R′H X = Cl, Br, I
(:R2NH = diisopropylamine, TMP)
Like many organolithium reagents, Hauser bases are generally used for metalation reagents. iPr2NMgBr selectively magnesiate carboxamides.
iPr2NMgX (X = Cl, Br) effect the deprotonation thiophenes. and phenylsulphonyl-substituted indoles.
Turbo-Hauser base
A major disadvantage of Hauser bases is their poor solubility in THF. In consequence, the metalation rates are slow and a large excess of base is required (e.g., 10 equiv.). This circumstance complicates the functionalization of the metaled intermediate with an electrophile. Improved solubility and reactivity can be achieved by adding stoichiometric amounts of LiCl to the Hauser base. These so-called Turbo-Hauser bases like e.g. TMPMgCl·LiCl and iPr2NMgCl·LiCl are commercially available. They show an enhanced kinetic basicity, regioselectivity and functional group tolerance.
References
Magnesium compounds | Hauser base | Chemistry | 661 |
1,847,936 | https://en.wikipedia.org/wiki/Honi%20HaMe%27agel | Honi HaMe'agel () was a tanna or Jewish scholar of the 1st century BC, the scholars from whose teachings the Mishnah was derived.
The Babylonian and Jerusalem Talmuds both provide examples of Jewish miracle workers, including Honi, such as in Jerusalem Talmud Taanit 3:10, 66d and Babylonian Talmud Taanit 19a; 23a.
Circle drawing incident
His surname is derived from an incident in which, according to the Babylonian Talmud, his prayer for rain was miraculously answered. On one occasion, when God did not send rain well into the winter (in Israel, it rains mainly in the winter), Honi drew a circle in the dust, stood inside it, and informed God that he would not move until it rained. When it began to drizzle, Honi told God that he was not satisfied and expected more rain; it then began to pour. He explained that he wanted a calm rain, at which point the rain calmed to a normal rain.
He was almost put into herem (excommunication) for the above incident in which he showed "dishonor" to God, as if he had imposed himself upon God. However, Simeon ben Shetach, the brother of Salome Alexandra, queen regnant of Hasmonean Judah, excused him, saying that Honi had a special relationship with God.
Two variations of this story appear in the Talmud, in Taanit 19a and 23a.
Extended sleep story
Two variations of a story are recorded—in the Babylonian and Jerusalem Talmuds—in which Honi fell asleep for decades before awakening. The story provides a Jewish version on the theme of a person or persons (as the Seven Sleepers) sleeping for many decades and waking to find a changed world—a theme originating in the story of Epimenides—found in many divergent cultures and traditions, and in modern times associated especially with the Rip Van Winkle story.
In the Babylonian Talmud (Carob tree story)
The Babylonian Talmud tells the following story, in which Honi slept for 70 years, before awaking and then dying:
In the Jerusalem Talmud
In the Jerusalem Talmud, the circle-drawing story is notably missing (except in the Mishnah), and the sleep theme does not manifest as the carob story. Instead, the story is about Honi sleeping in a cave for seventy years, then returning to see that the Temple in Jerusalem had been rebuilt, where he was able to prove his identity:
Unlike the Babylonian Talmud story, the account in the Jerusalem Talmud does not describe Honi's death. This more closely resembles the Epimenides sleep story in which Epimenides can pass on his message. According to one source, this difference could be specifically because of the two pieces this story is based on: Honi's death in Josephus and the Epimenides sleep theme. The idea would be that in the Jerusalem Talmud's case, the author more closely followed the Epimenides story to get their point across, while in the Babylonian Talmud, the author had a more metaphorical approach to his death in Josephus. The story of Honi the Circle-Maker is also quoted in Midrash Tehillim, chapter 126.
Death
According to Josephus in Antiquities of the Jews, Honi met his end in the context of conflict between the Hasmonean brothers Hyrcanus II, backed by the Pharisees and advised by Antipater the Idumaean, and Aristobulus II, backed by the Sadducees. Around 63 BCE, Honi was captured by the followers of Hyrcanus besieging Jerusalem and was asked to pray for the demise of their opponents. Honi, however, prayed: "Lord of the universe, as the besieged and the besiegers both belong to Your people, I beseech You not to answer the evil prayers of either." After this, the followers of Hyrcanus stoned him to death.
The Babylonian Talmud records a different story of his death, as part of the aforementioned carob tree story. Samuel Eidels (d. 1631) explains the discrepancy between the Talmud and Josephus by stating that Honi was presumed killed by Hyrcanus II's men, but in reality was put into a deep sleep or coma for 70 years, and only then died.
Honi's grave is found near the town of Hatzor HaGlilit in northern Israel.
His Yahrzeit is 5 Iyar.
Explanation of the word HaMe'agel
"HaMe'agel" in Hebrew means "circle maker". Samuel Klein suggested that the term "circle maker" relates to Honi's profession as a roofer (in Hebrew Me'agel). It was customary for sages in the Talmud to be called by their profession. Rollers for compressing plaster and mud on roofs during the Hellenistic period were found at Mount Gerizim. In the time of Honi, these rollers are the tools of the trade for a me'agel/circle maker/roofer. The Mishna in Maakot 2:1 calls this roofer a "circle maker" ("me'agel"). The term circle maker has a double meaning - profession and a label to describe Honi's drawing circles to interact with God.
Seder HaDoroth however, writes that the name is toponymic, as Honi was from a town named Maglu (see Seder HaTanna'im VehaAmora'im).
See also
Epimenides
Line in the sand
Magic circle
Rainmaking (ritual)
Rip Van Winkle
Seven Sleepers and Khidr
Zisurrû
References
Mishnah rabbis
1st-century BCE rabbis
Talmud rabbis of Syria Palaestina
Sleep in mythology and folklore | Honi HaMe'agel | Biology | 1,208 |
36,638,816 | https://en.wikipedia.org/wiki/Armenian%20eternity%20sign | The Armenian eternity sign (⟨֎ ֍⟩, ) or Arevakhach (, "Sun Cross") is an ancient Armenian national symbol and a symbol of the national identity of the Armenian people. It is one of the most common symbols in Armenian architecture, carved on khachkars and on walls of churches.
Evolution and use
In medieval Armenian culture, the eternity sign symbolized the concept of everlasting, celestial life. From the 1st century BC, it appeared on Armenian steles; later it became part of khachkar symbolism. Around the 8th century the use of the Armenian symbol of eternity had become a long established national iconographical practice, and it has kept its meaning in modern times. Besides being one of the main components of khachkars, it can be found on church walls, tomb stones and other architectural monuments. Notable churches with the eternity sign include the Mashtots Hayrapet Church of Garni, Horomayr Monastery, Nor Varagavank, Tsitsernavank Monastery. An identical symbol appears in the reliefs of the Divriği Great Mosque and Hospital, and is likely a borrowing from earlier Armenian churches of the area. It can also be found on Armenian manuscripts.
The eternity sign is used on the logos of government agencies and on commemorative coins, as well as Armenian government agencies and non-government organizations and institutions in Armenia and the Armenian diaspora.
The symbol is also used by Armenian neopagan organizations and their followers. It is called by them "Arevakhach" (, "sun cross").
ArmSCII and Unicode
In ArmSCII, Armenian Standard Code for Information Interchange, an Armenian eternity sign has been encoded in 7-bit and 8-bit standard and ad hoc encodings since at least 1987. In 2010 the Armenian National Institute of Standards suggested encoding an Armenian Eternity sign in the Unicode character set, and both left-facing ⟨֎⟩ and right-facing ⟨֍⟩ Armenian eternity signs were included in Unicode version 7.0 when it was released in June 2014.
Gallery
Churches
Modern statues and sculptures
Logos
See also
Borjgali
Castro culture (Economy and Arts, Stonework, Metallurgy)
Hilarri (Basque steles)
Lists of national symbols
Petroglyph
Pictish stone
Picture stones of Gotland
Triskelion
References
External links
Hayastan All Armenian Fund. Telethon 2010 – Water is Life. "Water is Life indeed and as you can see in the design, the water turns into the Armenian eternity symbol as it flows out of the helping hands."
Downtown, North End. "Armenian Heritage Park to participate Saturday in World Labyrinth Day", Posted by Jeremy C. Fox April 29, 2013. – "A single jet of water and the symbol of eternity mark its center, representing hope and rebirth."
Armenian Engineers & Scientists of America. "The Armenian Engineers and Scientists of America (AESA) logo is an ancient symbol used in Armenian architecture and carvings. The symbol signifies Eternal Life – in Armenian Haverjoutian Nshan or Sign of Eternity."
Armenian Monuments Awareness Project
Ancient Armenian religion
Armenian mythology
Infinity
Mathematical symbols
National symbols of Armenia
Rotational symmetry
Time in Armenia | Armenian eternity sign | Physics,Mathematics | 652 |
52,973,193 | https://en.wikipedia.org/wiki/Nano-FTIR | Nano-FTIR (nanoscale Fourier transform infrared spectroscopy) is a scanning probe technique that utilizes as a combination of two techniques: Fourier transform infrared spectroscopy (FTIR) and scattering-type scanning near-field optical microscopy (s-SNOM). As s-SNOM, nano-FTIR is based on atomic-force microscopy (AFM), where a sharp tip is illuminated by an external light source and the tip-scattered light (typically back-scattered) is detected as a function of tip position. A typical nano-FTIR setup thus consists of an atomic force microscope, a broadband infrared light source used for tip illumination, and a Michelson interferometer acting as Fourier-transform spectrometer. In nano-FTIR, the sample stage is placed in one of the interferometer arms, which allows for recording both amplitude and phase of the detected light (unlike conventional FTIR that normally does not yield phase information). Scanning the tip allows for performing hyperspectral imaging (i.e. complete spectrum at every pixel of the scanned area) with nanoscale spatial resolution determined by the tip apex size. The use of broadband infrared sources enables the acquisition of continuous spectra, which is a distinctive feature of nano-FTIR compared to s-SNOM.
Nano-FTIR is capable of performing infrared (IR) spectroscopy of materials in ultrasmall quantities and with nanoscale spatial resolution. The detection of a single molecular complex and the sensitivity to a single monolayer has been shown. Recording infrared spectra as a function of position can be used for nanoscale mapping of the sample chemical composition, performing a local ultrafast IR spectroscopy and analyzing the nanoscale intermolecular coupling, among others. A spatial resolution of 10 nm to 20 nm is routinely achieved.
For organic compounds, polymers, biological and other soft matter, nano-FTIR spectra can be directly compared to the standard FTIR databases, which allows for a straightforward chemical identification and characterization.
Nano-FTIR does not require special sample preparation and is typically performed under ambient conditions. It uses an AFM operated in noncontact mode that is intrinsically nondestructive and sufficiently gentle to be suitable for soft-matter and biological sample investigations. Nano-FTIR can be utilized from THz to visible spectral range (and not only in infrared as its name suggests) depending on the application requirements and availability of broadband sources. Nano-FTIR is complementary to tip-enhanced Raman spectroscopy (TERS), SNOM, AFM-IR and other scanning probe methods that are capable of performing vibrational analysis.
Basic principles
Nano-FTIR is based on s-SNOM, where the infrared beam from a light source is focused onto a sharp, typically metalized AFM tip and the backscattering is detected. The tip greatly enhances the illuminating IR light in the nanoscopic volume around its apex, creating a strong near field. A sample, brought into this near field, interacts with the tip electromagnetically and modifies the tip (back)scattering in the process. Thus by detecting tip scattering, one can obtain information about the sample.
Nano-FTIR detects the tip-scattered light interferometrically. The sample stage is placed into one arm of a conventional Michelson interferometer, while a mirror on a piezo stage is placed into another, reference arm. Recording the backscattered signal while translating the reference mirror yields an interferogram. The subsequent Fourier transform of this interferogram returns the near-field spectra of the sample.
Placement of the sample stage into one of the interferometer's arms (instead of outside of the interferometer as typically implemented in conventional FTIR) is a key element of nano-FTIR. It boosts the weak near-field signal due to interference with the strong reference field, helps to eliminate the background caused by parasitic scattering off everything that falls into large diffraction-limited beam focus, and most importantly, allows for recording of both amplitude s and phase φ spectra of the tip-scattered radiation. With the detection of phase, nano-FTIR provides complete information about near fields, which is essential for quantitative studies and many other applications. For example, for soft matter samples (organics, polymers, biomaterials, etc.), φ directly relates to the absorption in the sample material. This permits a direct comparison of nano-FTIR spectra with conventional absorption spectra of the sample material, thus allowing for simple spectroscopic identification according to standard FTIR databases.
History
Nano-FTIR was first described in 2005 in a patent by Ocelic and Hillenbrand as Fourier-transform spectroscopy of tip-scattered light with an asymmetric spectrometer (i.e. the tip/sample placed inside one of the interferometer arms). The first realization of s-SNOM with FTIR was demonstrated in 2006 in the laboratory of F. Keilmann using a mid-infrared source based on a simple version of nonlinear difference-frequency generation (DFG). However, the mid-IR spectra in this realization were recorded using dual comb spectroscopy principles, yielding a discrete set of frequencies and thus demonstrating a multiheterodyne imaging technique rather than nano-FTIR. The first continuous spectra were recorded only in 2009 in the same laboratory using a supercontinuum IR beam also obtained by DFG in GaSe upon superimposing two pulsed trains emitted from Er-doped fiber laser. This source further allowed in 2011 for the first assessment of nanoscale-resolved spectra of SiC with excellent quality and spectral resolution. At the same time, Huth et al. in the laboratory of R. Hillenbrand used IR radiation from a simple glowbar source in combination with the principles of Fourier-transform spectroscopy, to record IR spectra of p-doped Si and its oxides in a semiconductor device. In the same work the term nano-FTIR was first introduced. However, an insufficient spectral irradiance of glowbar sources limited the applicability of the technique to the detection of strongly-resonant excitations such phonons; and the early supercontinuum IR laser sources, while providing more power, had very narrow bandwidth (<300 cm−1). Further attempt to improve the spectral power, while retaining the large bandwidth of a glowbar source was made by utilizing the IR radiation from a high temperature argon arc source (also known as plasma source). However, due to lack of commercial availability and rapid development of the IR supercontinium laser sources, plasma sources are not widely utilized in nano-FTIR.
The breakthrough in nano-FTIR came upon the development of high-power broadband mid-IR laser sources, which provided large spectral irradiance in a sufficiently large bandwidth (mW-level power in ~1000 cm-1 bandwidth) and enabled truly broadband nanoscale-resolved material spectroscopy capable of detecting even the weakest vibrational resonances. Particularly, it has been shown that nano-FTIR is capable of measuring molecular fingerprints which match well with far-field FTIR spectra, owing to the asymmetry of the nano-FTIR spectrometer that provides phase and thus gives access to the molecular absorption. Recently, the first nanoscale-resolved infrared hyperspectral imaging of a co-polymer blend was demonstrated, which allowed for the application of statistical techniques such as multivariate analysis – a widely used tool for heterogeneous sample analysis.
Additional boost to the development of nano-FTIR came from the utilization of the synchrotron radiation that provide extreme bandwidth, yet at the expense of weaker IR spectral irradiance compared to broadband laser sources.
Commercialization
The nano-FTIR technology has been commercialized by neaspec – a Germany-based spin-off company of the Max Planck Institute of Biochemistry founded by Ocelic, Hillenbrand and Keilmann in 2007 and based on the original patent by Ocelic and Hillenbrand. The detection module optimized for broadband illumination sources was first made available in 2010 as a part of the standard neaSNOM microscope system. At this time, broadband IR-lasers have not been yet commercially available, however experimental broadband IR-lasers prove that the technology works perfect and that it has a huge application potential across many disciplines. The first nano-FTIR was commercially available in 2012 (supplied with still experimental broadband IR-laser sources), becoming the first commercial system for broadband infrared nano-spectroscopy. In 2015 neaspec develops and introduces Ultrafast nano-FTIR, the commercial version of ultrafast nano-spectroscopy. Ultrafast nano-FTIR is a ready-to-use upgrade for nano-FTIR to enable pump-probe nano-spectroscopy at best-in-class spatial resolution. The same year the development of a cryo-neaSNOM – the first system of its kind to enable nanoscale near-field imaging & spectroscopy at cryogenic temperatures – was announced.
Advanced capabilities
Synchrotron beamlines integration
Nano-FTIR systems can be easily integrated into synchrotron radiation beamlines. The use of synchrotron radiation allows for acquisition of an entire mid-infrared spectrum at once. Synchrotrons radiation has already been utilized in synchrotron infrared microscopectroscopy - the technique most widely used in biosciences, providing information on chemistry on microscales of virtually all biological specimens, like bone, plants, and other biological tissues. Nano-FTIR brings the spatial resolution to 10-20 nm scale (vs. ~2-5 μm in microspectroscopy), which has been utilized for broadband spatially-resolved spectroscopy of crystalline and phase-change materials, semiconductors, minerals, biominerals and proteins.
Ultrafast spectroscopy
Nano-FTIR is highly suitable for performing local ultrafast pump-probe spectroscopy due to intereferometric detection and an intrinsic ability to vary the probe delay time. It has been applied for studies of ultrafast nanoscale plasmonic phenomena in Graphene, for performing nanospectroscopy of InAs nanowires with subcycle resolution and for probing the coherent vibrational dynamics of nanoscopic ensembles.
Quantitative studies
The availability of both amplitude and phase of the scattered field and theoretically well understood signal formation in nano-FTIR allow for the recovery of both real and imaginary parts of the dielectric function, i.e. finding the index of refraction and the extinction coefficient of the sample. While such recovery for arbitrarily-shaped samples or samples exhibiting collective excitations, such as phonons, requires a resource-demanding numerical optimization, for soft matter samples (polymers, biological matter and other organic materials) the recovery of the dielectric function could often be performed in real time using fast semi-analytical approaches. One of such approaches is based on the Taylor expansion of the scattered field with respect to a small parameter that isolates the dielectric properties of the sample and allows for a polynomial representation of measured near-field contrast. With an adequate tip-sample interaction model and with known measurement parameters (e.g. tapping amplitude, demodulation order, reference material, etc.), the sample permittivity can be determined as a solution of a simple polynomial equation
Subsurface analysis
Near-field methods, including nano-FTIR, are typically viewed as a technique for surface studies due to short probing ranges of about couple tip radii (~20-50 nm). However it has been demonstrated that within such probing ranges, s-SNOM is capable of detecting subsurface features to some extents, which could be used for the investigations of samples capped by thin protective layers, or buried polymers, among others.
As a direct consequence of being quantitative technique (i.e. capable of highly reproducible detection of both near-field amplitude & phase and well understood near-field interaction models), nano-FTIR also provides means for the quantitative studies of the sample interior (within the probing range of the tip near field, of course). This is often achieved by a simple method of utilizing signals recorded at multiple demodulation orders naturally returned by nano-FTIR in the process of background suppression. It has been shown that higher harmonics probe smaller volumes below the tip, thus encoding the volumetric structure of a sample. This way, nano-FTIR has a demonstrated capability for the recovery of thickness and permittivity of layered films and nanostructures, which has been utilized for the nanoscale depth profiling of multiphase materials and high-Tc cuprate nanoconstriction devices patterned by focused ion beams. In other words, nano-FTIR has a unique capability of recovering the same information about thin-film samples that is typically returned by ellipsometry or impedance spectroscopy, yet with nanoscale spatial resolution. This capability proved crucial for disentangling different surface states in topological insulators.
Operation in liquid
Nano-FTIR uses scattered IR light to obtain information about the sample and has the potential to investigate electrochemical interfaces in-situ/operando and biological (or other) samples in their natural environment, such as water. The feasibility of such investigations has already been demonstrated by acquisition of nano-FTIR spectra through a capping Graphene layer on top of a supported material or through Graphene suspended on a perforated silicon nitride membrane (using the same s-SNOM platform that nano-FTIR utilizes).
Cryogenic environment
Reveling the fundamentals of phase transitions in superconductors, correlated oxides, Bose-Einstein condensates of surface polaritons, etc. require spectroscopic studies at the characteristically nanometer length scales and in cryogenic environment. Nano-FTIR is compatible with cryogenic s-SNOM that has already been utilized for reveling a nanotextured coexistence of metal and correlated Mott insulator phases in Vanadium oxide near the metal-insulator transition.
Special atmosphere environments
Nano-FTIR can be operated in different atmospheric environments by enclosing the system into an isolated chamber or a glove box. Such operation has already been used for the investigation of highly reactive Lithium-ion battery components.
Applications
Nano-FTIR has a plenitude of applications, including polymers and polymer composites, organic films, semiconductors, biological research (cell membranes, proteins structure, studies of single viruses), chemistry and catalysis, photochemistry, minerals and biominerals, geochemistry, corrosion and materials sciences, low-dimensional materials, photonics, energy storage, cosmetics, pharmacology and environmental sciences.
Materials and chemical sciences
Nano-FTIR has been used for the nanoscale spectroscopic chemical identification of polymers and nanocomposites, for in situ investigation of structure and crystallinity of organic thin films, for strain characterization and relaxation in crystalline materials and for high-resolution spatial mapping of catalytic reactions, among others.
Biological and pharmaceutical sciences
Nano-FTIR has been used for investigation of protein secondary structure, bacterial membrane, detection and studies of single viruses and protein complexes. It has been applied to the detection of biominerals in bone tissue. Nano-FTIR, when coupled with THz light, can also be applied to cancer and burn imaging with high optical contrast.
Semiconductor industry and research
Nano-FTIR has been used for nanoscale free carrier profiling and quantification of free carrier concentration in semiconductor devices, for evaluation of ion beam damage in nanoconstriction devices, and general spectroscopic characterization of semiconductor materials.
Theory
High-harmonic demodulation for background suppression
The nano-FTIR interferometrically detects light scattered from the tip-sample system, . The power at the detector can be written as
where is the reference field. The scattered field can be written as
and is dominated by parasitic background scattering, , from the tip shaft, cantilever sample roughness and everything else which falls into the diffraction-limited beam focus. To extract the near-field signal, , originating from the "hot-spot" below the tip apex (which carries the nanoscale-resolved information about the sample properties) a small harmonic modulation of the tip height H (i.e. oscillating the tip) with frequency Ω is provided and the detector signal is demodulated at higher harmonics of this frequency nΩ with n=1,2,3,4,... The background is nearly insensitive to small variations of the tip height and is nearly eliminated for sufficiently high demodulation orders (typically ). Mathematically this can be shown by expanding and into a Fourier series, which yields the following (approximated) expression for the demodulated detector signal:
where is the complex-valued number that is obtained by combining the lock-in amplitude, , and phase, , signals, is the n-th Fourier coefficient of the near-field contribution and C. C. stands for the complex conjugate terms. is the zeroth-order Fourier coefficient of the background contribution and is often called the multiplicative background because it enters the detector signal as a product with . It cannot be removed by the high-harmonic demodulation alone. In nano-FTIR the multiplicative background is eliminated as described below.
Asymmetric FTIR spectrometer
To acquire a spectrum, the reference mirror is continuously translated while recording the demodulated detector signal as a function of the reference mirror position , yielding an interferogram . This way the phase of the reference field changes according to for each spectral component of the reference field and the detector signal can thus be written as
where is the reference field at zero delay . To obtain the nano-FTIR spectrum, , the interferogram is Fourier-transformed with respect to . The second term in the above equation does not depend on the reference mirror position and after the Fourier transformation contributes only to the DC signal. Thus for only the near-field contribution multiplied by the reference field stays in the acquired spectrum:
This way, besides providing the interferometric gain, the asymmetric interferometer utilized in nano-FTIR also eliminates the multiplicative background, which otherwise could be a source of various artifacts and is often overlooked in other s-SNOM based spectroscopies.
Normalization
Following the standard FTIR practice, spectra in nano-FTIR are normalized to those obtained on a known, preferably spectrally-flat reference material. This eliminates the generally unknown reference field and any instrumental functions, yielding spectra of the near-field contrast:
Near-field contrast spectra are generally complex-valued, reflecting on the possible phase delay of the sample-scattered field with respect to the reference. Near-field contrast spectra depend nearly exclusively on the dielectric properties of sample material and can be used for its identification and characterization.
Nano-FTIR absorption spectroscopy
For the purpose of describing near-field contrasts for optically thin samples composed of polymers, organics, biological matter and other soft matter (so called weak oscillators), the near-field signal to a good approximation can be expressed as:
,
where is the surface response function that depends on the complex-valued dielectric function of the sample and can be also viewed as the reflection coefficient for evanescent waves that constitute the near field of the tip. That is, the spectral dependence of is determined exclusively by the sample reflection coefficient. The latter is purely real and acquires an imaginary part only in narrow spectral regions around the sample absorption lines. This means that the spectrum of an imaginary part of the near-field contrast resembles the conventional FTIR absorbance spectrum, , of the sample material:. It is therefore convenient to define the nano-FTIR absorption , which directly relates to the sample absorbance spectrum:
It can be used for direct sample identification and characterization according to the standard FTIR databases without the need of modeling the tip-sample interaction.
For phononic and plasmonic samples in the vicinity of the corresponding surface surface resonances, the relation might not hold. In such cases the simple relation between and can not be obtained, requiring modeling of the tip-sample interaction for spectroscopic identification of such samples.
Analytical and numerical simulations
Significant efforts have been put towards simulating nano-FTIR electric field and complex scattering signal through numerical methods (using commercial proprietary software such as CST Microwave Studio, Lumerical FDTD, and COMSOL Multiphysics) as well as through analytical models (such as through finite dipole and point dipole approximations). Analytical simulations tend to be more simplified and inaccurate, while numerical methods are more rigorous but computationally expensive.
References
External links
Infrared Nanoscopy Laboratory of Fritz Keilman (Ludwigs-Maximilians-Universität)
Nanooptics group of Rainer Hillenbrand (CIC nanoGUNE)
Nano-Optics & Metamaterials group of Thomas Taubner (RWTH Aachen)
Infrared Nano-Optics of Quantum Materials group of Dmitri Basov (UC San Diego)
Scanning probe microscopy
Infrared spectroscopy
Scientific techniques | Nano-FTIR | Physics,Chemistry,Materials_science | 4,360 |
59,103,038 | https://en.wikipedia.org/wiki/Psychological%20inertia | Psychological inertia is the tendency to maintain the status quo (or default option) unless compelled by a psychological motive to intervene or reject this.
Psychological inertia is similar to the status-quo bias but there is an important distinction in that psychological inertia involves inhibiting any action, whereas the status-quo bias involves avoiding any change which would be perceived as a loss.
Research into psychological inertia is limited, particularly into its causes, but it has been seen to affect decision-making by causing individuals to automatically choose or prefer the default option, even if there is a more beneficial option available to them, unless motivated to reject this option. For example, psychological inertia may cause individuals to continue with their investments later than they should, despite information telling them otherwise, causing them to suffer greater losses than they would have if they had disinvested earlier.
Psychological inertia has also seen to be relevant in areas of health, crime and within the workplace.
Loss aversion vs psychological inertia
David Gal and Derek Rucker both suggest that psychological inertia could be a more suitable explanation for phenomena such as the status-quo bias and the endowment effect than loss aversion.
Status quo bias
The psychological inertia account asserts that the reason individuals choose to remain at the status quo is due to a lack of psychological motive to change this behaviour rather than through the weighing up of losses and gains in this decision. Both explanations were tested by David Gal in a study where subjects were asked to imagine that they owned a quarter minted in either Denver or Philadelphia. They were then given the choice of exchanging their coin with one minted in the other city, assuming insignificant time and effort involved in this process. It was found that 85% of participants chose to retain their original coin which can be explained by the inertia account of remaining at the status quo. However, the loss aversion account is unable to explain this decision as it does not provide insight into a propensity towards the status-quo when the option values are equivalent.
Endowment effect
The endowment effect, i.e. greater value being placed on objects that are owned than those that are not, has been shown to be caused by loss aversion. This was demonstrated in Daniel Kahneman's study in 1990 where participants who were given a mug demanded, on average, around seven dollars to part with it. Whereas, individuals who were not given a mug were only willing to spend, on average, around three dollars on the same mug. This therefore demonstrated that losses exert a greater impact than gains. However, it could also be seen as evidence for psychological inertia as the participants were provided with the same objects and therefore, as they were indifferent to them, they chose to maintain the status quo as there was no incentive to trade.
Inability to break with tradition
The 1998 article "Psychological Inertia" by James Kowalick refers to a company where the president was displeased that company management had little knowledge of what was going on in the manufacturing department. The management team was not approachable and looked down on employees that were not managers. "Remaining behind the sacred doors of one's managerial office had become quite a tradition." To address this issue, the president asked each manager to present a manufacturing procedure in detail at the staff meeting while the other managers asked penetrating questions. As a result, in short time, managers were on the production floor learning the procedures. This form of PI represents "cultural and traditional programming".
Examples and applications
Health
Avolition has been understood as a core symptom in schizophrenia, however, the drives of it are unclear. One possible drive that may underlie avolition is psychological inertia. It has been argued that as individuals with schizophrenia may be less able to convert their preferences into actions, they may display an increased tendency to maintain a current state, even if they attribute greater value to a different option available. Therefore, this causes these individuals to display greater levels of psychological inertia, and since this process inhibits their action, its presence could drive avolition. James Gold found that motivational impairments of schizophrenia may be associated with abnormalities in estimating the "cost" of effortful behaviour leading to increased psychological inertia which, in turn, could lead to increased avolition in these individuals. However, research into links between psychological inertia and schizophrenia is limited as is their relationship to avolition. For example, research is needed to explore whether the differences in levels of psychological inertia in individuals with schizophrenia only occur when there is a need to engage high levels of inertia or when the individual displays a high level of avolition. Research has shown, however, that the differences in levels of psychological inertia among individuals with schizophrenia is not only due to avolition but could be caused by attention deficits or action-readiness deficits.
Crime
Psychological inertia is believed to be one explanation factor in crime continuity, that is the persistence of criminal behaviour. Glenn Walter's psychological inertia theorem states that crime continuity is partly caused by cognitive factors that account for the continuity in behaviour between past and future criminality and derives from his broader 'lifestyle theory' model, which explains the overall development of a criminal lifestyle. Walter's theorem is based upon Newton's law of inertia which states that a body will remain in motion until acted upon by an outside force, in which here the body in motion is crime.
Within this theorem, Walter attributes six slow-changing variables that when combined link past criminality with future criminality.
These six cognitive variables are:
Criminal thinking (antisocial attitudes and irrational thought patterns)
Positive outcome expectancies for crime (belief that crime will have specific positive outcomes)
Attribution biases (tendency to view the world as hostile and others as malicious)
Efficacy expectations (lack of confidence in one's ability to avoid criminal opportunities in the future)
Goals (i.e. focus on short-term goals which becomes detrimental to long-term goals)
Values (pursuit of self-indulgent pleasure and immediate gratification)
The psychological inertia theorem argues that criminal involvement gives rise to these six cognitive variables which then encourage further offending behaviour.
Theories surrounding the expectation of behavioural continuity are a topic of debate in the criminal justice community. But the conventional wisdom that past behaviour is the best predictor of future behaviour has generally led to "an expectation that offenders with histories of criminal violence in the community are at increased risk for disruptive conduct in prison [and] has been operationalized as a routine component in prison risk classifications".
Workplace
Psychological inertia has been found to be prevalent in change management within the workplace due to the fact it causes individuals to feel anxiety and fear as a result of any type of change away from the status-quo which may bring new responsibilities and roles. There are a variety of different interventions that have been suggested to overcome this psychological inertia which include providing fuller information including explaining the benefits that such a change will bring, causing people to feel less anxious and more motivated to carry out this change.
See also
Cognitive inertia
Knowledge inertia
Social inertia
References
Cognitive biases
Cognitive inertia
Behavioral economics | Psychological inertia | Biology | 1,482 |
54,203,120 | https://en.wikipedia.org/wiki/Junghuhnia%20japonica | Junghuhnia japonica is a species of poroid crust fungus in the family Steccherinaceae. The type specimen was collected in Ōkuchi, Japan, growing on a rotting log of Castanopsis. The fungus is only known from the type locality. Its cylindric spores measure 4–5 by 2–2.4 μm and are smooth and hyaline. J. japonica has two types of cystidia. One type is thick walled and heavily encrusted, measuring 40–70 by 9–15 μm. The other type is tubular, smooth, and thin walled, measuring 20–35 by 4–8 μm. The latter type, which have an oily or granular appearance under the microscope, are known as gloeocystidia.
The fungus was described as new to science in 1999 by mycologists Maria Núñez & Leif Ryvarden. J. japonica is similar in morphology to J. luteoalba but that species has narrower spores and lacks gloeocystidia.
References
Fungi described in 2005
Fungi of Japan
Steccherinaceae
Taxa named by Leif Ryvarden
Fungus species | Junghuhnia japonica | Biology | 245 |
99,820 | https://en.wikipedia.org/wiki/Carbon%20group | |-
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The carbon group is a periodic table group consisting of carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), and flerovium (Fl). It lies within the p-block.
In modern IUPAC notation, it is called group 14. In the field of semiconductor physics, it is still universally called group IV. The group is also known as the tetrels (from the Greek word tetra, which means four), stemming from the Roman numeral IV in the group name, or (not coincidentally) from the fact that these elements have four valence electrons (see below). They are also known as the crystallogens or adamantogens.
Characteristics
Chemical
Like other groups, the members of this family show patterns in electron configuration, especially in the outermost shells, resulting in trends in chemical behavior:
Each of the elements in this group has 4 electrons in its outer shell. An isolated, neutral group 14 atom has the s2 p2 configuration in the ground state. These elements, especially carbon and silicon, have a strong propensity for covalent bonding, which usually brings the outer shell to eight electrons. Bonds in these elements often lead to hybridisation where distinct s and p characters of the orbitals are erased. For single bonds, a typical arrangement has four pairs of sp3 electrons, although other cases exist too, such as three sp2 pairs in graphene and graphite. Double bonds are characteristic for carbon (alkenes, ...); the same for π-systems in general. The tendency to lose electrons increases as the size of the atom increases, as it does with increasing atomic number.
Carbon alone forms negative ions, in the form of carbide (C4−) ions.
Silicon and germanium, both metalloids, each can form +4 ions.
Tin and lead both are metals, while flerovium is a synthetic, radioactive (its half life is very short, only 1.9 seconds) element that may have a few noble gas-like properties, though it is still most likely a post-transition metal. Tin and lead are both capable of forming +2 ions. Although tin is chemically a metal, its α allotrope looks more like germanium than like a metal and it is a poor electric conductor.
Among main group (groups 1, 2, 13–17) alkyl derivatives QRn, where n is the standard bonding number for Q (see lambda convention), the group 14 derivatives QR4 are notable in being electron-precise: they are neither electron-deficient (having fewer electrons than an octet and tending to be Lewis acidic at Q and usually existing as oligomeric clusters or adducts with Lewis bases) nor electron-excessive (having lone pair(s) at Q and tending to be Lewis basic at Q). As a result, the group 14 alkyls have low chemical reactivity relative to the alkyl derivatives of other groups. In the case of carbon, the high bond dissociation energy of the C–C bond and lack of electronegativity difference between the central atom and the alkyl ligands render the saturated alkyl derivatives, the alkanes, particularly inert.
Carbon forms tetrahalides with all the halogens. Carbon also forms many oxides such as carbon monoxide, carbon suboxide, and carbon dioxide. Carbon forms a disulfide an a diselenide.
Silicon forms several hydrides; two of them are SiH4 and Si2H6. Silicon forms tetrahalides with fluorine (SiF4), chlorine (SiCl4), bromine (SiBr4), and iodine (SiI4). Silicon also forms a dioxide and a disulfide. Silicon nitride has the formula Si3N4.
Germanium forms five hydrides. The first two germanium hydrides are GeH4 and Ge2H6. Germanium forms tetrahalides with all halogens except astatine and forms dihalides with all halogens except bromine and astatine. Germanium bonds to all natural single chalcogens except polonium, and forms dioxides, disulfides, and diselenides. Germanium nitride has the formula Ge3N4.
Tin forms two hydrides: SnH4 and Sn2H6. Tin forms dihalides and tetrahalides with all halogens except astatine. Tin forms monochalcogenides with naturally occurring chalcogens except polonium, and forms dichalcogenides with naturally occurring chalcogens except polonium and tellurium.
Lead forms one hydride, which has the formula PbH4. Lead forms dihalides and tetrahalides with fluorine and chlorine, and forms a dibromide and a diiodide, although the tetrabromide and tetraiodide of lead are unstable. Lead forms four oxides, a sulfide, a selenide, and a telluride.
There are no known compounds of flerovium.
Physical
The boiling points of the carbon group tend to get lower with the heavier elements. At standard pressure, carbon, the lightest carbon group element, sublimes at 3825 °C. Silicon's boiling point is 3265 °C, germanium's is 2833 °C, tin's is 2602 °C, and lead's is 1749 °C. Flerovium is predicted to boil at −60 °C. The melting points of the carbon group elements have roughly the same trend as their boiling points. Silicon melts at 1414 °C, germanium melts at 939 °C, tin melts at 232 °C, and lead melts at 328 °C.
Carbon's crystal structure is hexagonal; at high pressures and temperatures it forms diamond (see below). Silicon and germanium have diamond cubic crystal structures, as does tin at low temperatures (below 13.2 °C). Tin at room temperature has a tetragonal crystal structure. Lead has a face-centered cubic crystal structure.
The densities of the carbon group elements tend to increase with increasing atomic number. Carbon has a density of 2.26 g·cm−3; silicon, 2.33 g·cm−3; germanium, 5.32 g·cm−3; tin, 7.26 g·cm−3; lead, 11.3 g·cm−3.
The atomic radii of the carbon group elements tend to increase with increasing atomic number. Carbon's atomic radius is 77 picometers, silicon's is 118 picometers, germanium's is 123 picometers, tin's is 141 picometers, and lead's is 175 picometers.
Allotropes
Carbon has multiple allotropes. The most common is graphite, which is carbon in the form of stacked sheets. Another form of carbon is diamond, but this is relatively rare. Amorphous carbon is a third allotrope of carbon; it is a component of soot. Another allotrope of carbon is a fullerene, which has the form of sheets of carbon atoms folded into a sphere. A fifth allotrope of carbon, discovered in 2003, is called graphene, and is in the form of a layer of carbon atoms arranged in a honeycomb-shaped formation.
Silicon has two known allotropes that exist at room temperature. These allotropes are known as the amorphous and the crystalline allotropes. The amorphous allotrope is a brown powder. The crystalline allotrope is gray and has a metallic luster.
Tin has two allotropes: α-tin, also known as gray tin, and β-tin. Tin is typically found in the β-tin form, a silvery metal. However, at standard pressure, β-tin converts to α-tin, a gray powder, at temperatures below . This can cause tin objects in cold temperatures to crumble to gray powder in a process known as tin pest or tin rot.
Nuclear
At least two of the carbon group elements (tin and lead) have magic nuclei, meaning that these elements are more common and more stable than elements that do not have a magic nucleus.
Isotopes
There are 15 known isotopes of carbon. Of these, three are naturally occurring. The most common is stable carbon-12, followed by stable carbon-13. Carbon-14 is a natural radioactive isotope with a half-life of 5,730 years.
23 isotopes of silicon have been discovered. Five of these are naturally occurring. The most common is stable silicon-28, followed by stable silicon-29 and stable silicon-30. Silicon-32 is a radioactive isotope that occurs naturally as a result of radioactive decay of actinides, and via spallation in the upper atmosphere. Silicon-34 also occurs naturally as the result of radioactive decay of actinides.
32 isotopes of germanium have been discovered. Five of these are naturally occurring. The most common is the stable germanium-74, followed by stable germanium-72, stable germanium-70, and stable germanium-73. Germanium-76 is a primordial radioisotope.
40 isotopes of tin have been discovered. 14 of these occur in nature. The most common is tin-120, followed by tin-118, tin-116, tin-119, tin-117, tin-124, tin-122, tin-112, and tin-114: all of these are stable. Tin also has four radioisotopes that occur as the result of the radioactive decay of uranium. These isotopes are tin-121, tin-123, tin-125, and tin-126.
38 isotopes of lead have been discovered. 9 of these are naturally occurring. The most common isotope is lead-208, followed by lead-206, lead-207, and lead-204: all of these are stable. 5 isotopes of lead occur from the radioactive decay of uranium and thorium. These isotopes are lead-209, lead-210, lead-211, lead-212 and lead-214.
6 isotopes of flerovium (flerovium-284, flerovium-285, flerovium-286, flerovium-287, flerovium-288, and flerovium-289) have been discovered, all from human synthesis. Flerovium's most stable isotope is flerovium-289, which has a half-life of 2.6 seconds.
Occurrence
Carbon accumulates as the result of stellar fusion in most stars, even small ones. Carbon is present in the Earth's crust in concentrations of 480 parts per million, and is present in seawater at concentrations of 28 parts per million. Carbon is present in the atmosphere in the form of carbon monoxide, carbon dioxide, and methane. Carbon is a key constituent of carbonate minerals, and is in hydrogen carbonate, which is common in seawater. Carbon forms 22.8% of a typical human.
Silicon is present in the Earth's crust at concentrations of 28%, making it the second most abundant element there. Silicon's concentration in seawater can vary from 30 parts per billion on the surface of the ocean to 2000 parts per billion deeper down. Silicon dust occurs in trace amounts in Earth's atmosphere. Silicate minerals are the most common type of mineral on earth. Silicon makes up 14.3 parts per million of the human body on average. Only the largest stars produce silicon via stellar fusion.
Germanium makes up 2 parts per million of the Earth's crust, making it the 52nd most abundant element there. On average, germanium makes up 1 part per million of soil. Germanium makes up 0.5 parts per trillion of seawater. Organogermanium compounds are also found in seawater. Germanium occurs in the human body at concentrations of 71.4 parts per billion. Germanium has been found to exist in some very faraway stars.
Tin makes up 2 parts per million of the Earth's crust, making it the 49th most abundant element there. On average, tin makes up 1 part per million of soil. Tin exists in seawater at concentrations of 4 parts per trillion. Tin makes up 428 parts per billion of the human body. Tin(IV) oxide occurs at concentrations of 0.1 to 300 parts per million in soils. Tin also occurs in concentrations of one part per thousand in igneous rocks.
Lead makes up 14 parts per million of the Earth's crust, making it the 36th most abundant element there. On average, lead makes up 23 parts per million of soil, but the concentration can reach 20000 parts per million (2 percent) near old lead mines. Lead exists in seawater at concentrations of 2 parts per trillion. Lead makes up 1.7 parts per million of the human body by weight. Human activity releases more lead into the environment than any other metal.
Flerovium doesn't occur in nature at all, so it only exists in particle accelerators with a few atoms at a time.
History
Discoveries and uses in antiquity
Carbon, tin, and lead are a few of the elements well known in the ancient world, together with sulfur, iron, copper, mercury, silver, and gold.
Silicon as silica in the form of rock crystal was familiar to the predynastic Egyptians, who used it for beads and small vases; to the early Chinese; and probably to many others of the ancients. The manufacture of glass containing silica was carried out both by the Egyptians – at least as early as 1500 BCE – and by the Phoenicians. Many of the naturally occurring compounds or silicate minerals were used in various kinds of mortar for construction of dwellings by the earliest people.
The origins of tin seem to be lost in history. It appears that bronzes, which are alloys of copper and tin, were used by prehistoric man some time before the pure metal was isolated. Bronzes were common in early Mesopotamia, the Indus Valley, Egypt, Crete, Israel, and Peru. Much of the tin used by the early Mediterranean peoples apparently came from the Scilly Isles and Cornwall in the British Isles, where mining of the metal dates from about 300–200 BCE. Tin mines were operating in both the Inca and Aztec areas of South and Central America before the Spanish conquest.
Lead is mentioned often in early Biblical accounts. The Babylonians used the metal as plates on which to record inscriptions. The Romans used it for tablets, water pipes, coins, and even cooking utensils; indeed, as a result of the last use, lead poisoning was recognized in the time of Augustus Caesar. The compound known as white lead was apparently prepared as a decorative pigment at least as early as 200 BCE.
Modern discoveries
Amorphous elemental silicon was first obtained pure in 1824 by the Swedish chemist Jöns Jacob Berzelius; impure silicon had already been obtained in 1811. Crystalline elemental silicon was not prepared until 1854, when it was obtained as a product of electrolysis.
Germanium is one of three elements the existence of which was predicted in 1869 by the Russian chemist Dmitri Mendeleev when he first devised his periodic table. However, the element was not actually discovered for some time. In September 1885, a miner discovered a mineral sample in a silver mine and gave it to the mine manager, who determined that it was a new mineral and sent the mineral to Clemens A. Winkler. Winkler realized that the sample was 75% silver, 18% sulfur, and 7% of an undiscovered element. After several months, Winkler isolated the element and determined that it was element 32.
The first attempt to discover flerovium (then referred to as "element 114") was in 1969, at the Joint Institute for Nuclear Research, but it was unsuccessful. In 1977, researchers at the Joint Institute for Nuclear Research bombarded plutonium-244 atoms with calcium-48, but were again unsuccessful. This nuclear reaction was repeated in 1998, this time successfully.
Etymologies
Carbon comes from the Latin word carbo, meaning "charcoal".
Silicon comes from the Latin word silex (or silicis), meaning "flint".
Germanium comes from the Latin word Germania, the Latin name for Germany, which is the country where germanium was discovered.
Stannum comes from the Latin word stannum, meaning "tin", from or related to Celtic staen.
- The common name for stannum in English is tin, inherited directly from Old English. Possibly of common origin with stannum and staen.
Plumbum comes from the Latin word plumbum meaning lead.
- The common name for plumbum in English is lead, inherited directly from Old English.
Flerovium was named after Georgy Flyorov and his Institute.
Applications
Carbon is most commonly used in its amorphous form. In this form, carbon is used for steelmaking, as carbon black, as a filling in tires, in respirators, and as activated charcoal. Carbon is also used in the form of graphite, for example as the lead in pencils. Diamond, another form of carbon, is commonly used in jewelry. Carbon fibers are used in numerous applications, such as satellite struts, because the fibers are highly strong yet elastic.
Silicon dioxide has a wide variety of applications, including toothpaste, construction fillers, and silica is a major component of glass. 50% of pure silicon is devoted to the manufacture of metal alloys. 45% of silicon is devoted to the manufacture of silicones. Silicon is also commonly used in semiconductors since the 1950s.
Germanium was used in semiconductors until the 1950s, when it was replaced by silicon. Radiation detectors contain germanium. Germanium dioxide is used in fiber optics and wide-angle camera lenses. A small amount of germanium mixed with silver can make silver tarnish-proof. The resulting alloy is known as argentium sterling silver.
Solder is the most important use of tin; 50% of all tin produced goes into this application. 20% of all tin produced is used in tin plate. 20% of tin is used by the chemical industry. Tin is a constituent of numerous alloys, including pewter. Tin(IV) oxide has been commonly used in ceramics for thousands of years. Cobalt stannate is a tin compound which is used as a cerulean blue pigment.
80% of all lead produced goes into lead–acid batteries. Other applications for lead include weights, pigments, and shielding against radioactive materials. Lead was historically used in gasoline in the form of tetraethyllead, but this application has been discontinued due to concerns of toxicity.
Production
Carbon's allotrope diamond is produced mostly by Russia, Botswana, Congo, Canada, South Africa, and India. 80% of all synthetic diamonds are produced by Russia. China produces 70% of the world's graphite. Other graphite-mining countries are Brazil, Canada, and Mexico.
Silicon can be produced by heating silica with carbon.
There are some germanium ores, such as germanite, but these are not mined on account of being rare. Instead, germanium is extracted from the ores of metals such as zinc. In Russia and China, germanium is also separated from coal deposits. Germanium-containing ores are first treated with chlorine to form germanium tetrachloride, which is mixed with hydrogen gas. Then the germanium is further refined by zone refining. Roughly 140 metric tons of germanium are produced each year.
Mines output 300,000 metric tons of tin each year. China, Indonesia, Peru, Bolivia, and Brazil are the main producers of tin. The method by which tin is produced is to heat the tin mineral cassiterite (SnO2) with coke.
The most commonly mined lead ore is galena (lead sulfide). 4 million metric tons of lead are newly mined each year, mostly in China, Australia, the United States, and Peru. The ores are mixed with coke and limestone and roasted to produce pure lead. Most lead is recycled from lead batteries. The total amount of lead ever mined by humans amounts to 350 million metric tons.
Biological role
Carbon is a key element to all known life. It is in all organic compounds, for example, DNA, steroids, and proteins. Carbon's importance to life is primarily due to its ability to form numerous bonds with other elements. There are 16 kilograms of carbon in a typical 70-kilogram human.
Silicon-based life's feasibility is commonly discussed. However, it is less able than carbon to form elaborate rings and chains. Silicon in the form of silicon dioxide is used by diatoms and sea sponges to form their cell walls and skeletons. Silicon is essential for bone growth in chickens and rats and may also be essential in humans. Humans consume on average between 20 and 1200 milligrams of silicon per day, mostly from cereals. There is 1 gram of silicon in a typical 70-kilogram human.
A biological role for germanium is not known, although it does stimulate metabolism. In 1980, germanium was reported by Kazuhiko Asai to benefit health, but the claim has not been proven. Some plants take up germanium from the soil in the form of germanium oxide. These plants, which include grains and vegetables contain roughly 0.05 parts per million of germanium. The estimated human intake of germanium is 1 milligram per day. There are 5 milligrams of germanium in a typical 70-kilogram human.
Tin has been shown to be essential for proper growth in rats, but there is, as of 2013, no evidence to indicate that humans need tin in their diet. Plants do not require tin. However, plants do collect tin in their roots. Wheat and maize contain 7 and 3 parts per million respectively. However, the level of tin in plants can reach 2000 parts per million if the plants are near a tin smelter. On average, humans consume 0.3 milligrams of tin per day. There are 30 milligrams of tin in a typical 70-kilogram human.
Lead has no known biological role, and is in fact highly toxic, but some microbes are able to survive in lead-contaminated environments. Some plants, such as cucumbers contain up to tens of parts per million of lead. There are 120 milligrams of lead in a typical 70-kilogram human.
Flerovium has no biological role and instead is found and made only in particle accelerators.
Toxicity
Elemental carbon is not generally toxic, but many of its compounds are, such as carbon monoxide and hydrogen cyanide. However, carbon dust can be dangerous because it lodges in the lungs in a manner similar to asbestos.
Silicon minerals are not typically poisonous. However, silicon dioxide dust, such as that emitted by volcanoes can cause adverse health effects if it enters the lungs.
Germanium can interfere with such enzymes as lactate dehydrogenase and alcohol dehydrogenase. Organic germanium compounds are more toxic than inorganic germanium compounds. Germanium has a low degree of oral toxicity in animals. Severe germanium poisoning can cause death by respiratory paralysis.
Some tin compounds are toxic to ingest, but most inorganic compounds of tin are considered nontoxic. Organic tin compounds, such as trimethyltin and triethyltin are highly toxic, and can disrupt metabolic processes inside cells.
Lead and its compounds, such as lead acetates are highly toxic. Lead poisoning can cause headaches, stomach pain, constipation, and gout.
Flerovium is too radioactive to test if it's toxic or not although its high radioactivity alone would be toxic.
References
Groups (periodic table) | Carbon group | Chemistry | 5,022 |
58,968,943 | https://en.wikipedia.org/wiki/Ethylsarin | Ethylsarin (GE), also known as EA-1209, TL-1620 or T-2109, is an organophosphate nerve agent of the G-series. It is the ethylphosphonofluoridate analog of sarin.
References
G-series nerve agents
Acetylcholinesterase inhibitors
Isopropyl esters
Ethylphosphonofluoridates | Ethylsarin | Chemistry | 87 |
20,207,047 | https://en.wikipedia.org/wiki/Oxhide%20ingot | Oxhide ingots are heavy (20–30 kg) metal slabs, usually of copper but sometimes of tin, produced and widely distributed during the Mediterranean Late Bronze Age (LBA). Their shape resembles the hide of an ox with a protruding handle in each of the ingot’s four corners. Early thought was that each ingot was equivalent to the value of one ox. However, the similarity in shape is simply a coincidence. The ingots' producers probably designed these protrusions to make the ingots easily transportable overland on the backs of pack animals. Complete or partial oxhide ingots have been discovered in Sardinia, Crete, Peloponnese, Cyprus, Cannatello in Sicily, Boğazköy in Turkey (ancient Hattusa, the Hittite capital), Qantir in Egypt (ancient Pi-Ramesses), and Sozopol in Bulgaria. Archaeologists have recovered many oxhide ingots from two shipwrecks off the coast of Turkey (one off Uluburun and one in Cape Gelidonya).
Context
The appearance of oxhide ingots in the archaeological record corresponds with the beginning of the bulk copper trade in the Mediterranean—approximately 1600 BC. The earliest oxhide ingots found come from Crete and date to the Late Minoan IB, approximately 1500 BC to 1450 BC. The latest oxhide ingots date to approximately 1000 BC, and were found on Sardinia. The copper trade was largely maritime: the principal sites where oxhide ingots are found are at sea, on the coast, and on islands.
Purposes
It is uncertain whether the oxhide ingots served as a form of currency. Ingots found in excavations at Mycenae are now part of the exhibits of the Numismatic Museum of Athens. Cemal Pulak argues that the weights of the Uluburun ingots are similar enough to have allowed "a rough but quick reckoning of a given quantity of raw metal prior to weighing". But George Bass proposes, via the Gelidonya ingots, whose weights are approximately the same if somewhat lower than the Uluburun ingot weights, that the weights were not standard and thus the ingots were not a currency. Another theory is that the oxhide shape, as well as the bun shape that some ingots took, was a visual statement that the ingot at hand is part of a legitimate trade. In Sardinia, oxhide ingot fragments have been found in hoards with bun ingots and scrap metal and, in some cases, in a metallurgical workshop. Citing this evidence, Vasiliki Kassianidou argues that the oxhide ingots "were meant to be used rather than to be kept as prestige goods".
Major finds
Uluburun shipwreck
In 1982, a diver discovered a shipwreck off the shore of Uluburun, Turkey. The ship contained 317 copper ingots in the normal oxhide shape, 36 with only two corner protrusions, 121 shaped like buns, and five shaped like pillows. The oxhide ingots (ingots with two or four protrusions) range in weight from after being cleaned of their corrosion. These ingots were found stacked in four rows following a herringbone pattern. The smooth sides of the ingots faced downwards, and the lowest layer rested on brushwood. There are three whole tin oxhide ingots, and there are many tin ingots cut into quarters or halves, with their corner protrusion(s) still intact. Besides metal ingots, the cargo included ivory, metal jewelry, and Mycenaean, Cypriot, and Canaanite pottery. Tree-ring dating of firewood from the ship gives an approximate date of 1300 BC. More than 160 copper oxhide ingots, 62 bun ingots, and some of the tin oxhide ingots have incised marks typically on their rough sides. Some of these marks—resembling fish, oars, and boats—relate to the sea, and they were probably incised after casting, when the ingot was received or exported.
Recently Yuval Goren proposed that the ten tons of copper ingots, one ton of tin ingots, and the resin stored in the Canaanite jars aboard the ship were one complete package. The recipients of the copper, tin, and resin would have used these materials for bronze casting through the lost-wax technique.
Cape Gelidonya shipwreck
In the early 1950s, divers found the remains of a shipwreck in Cape Gelidonya, off the coast of Turkey. The remains included a substantial amount of copper oxhide ingot material: 34 in full, five in half, 12 corners, and of random fragments. Twenty-four full copper oxhide ingots have stamps on their centers—usually of a circle containing intersecting lines. These stamps were likely made when the metal was soft. In addition, the ship contained numerous complete and incomplete copper bun-shaped ingots, rectangular tin bars, and Cypriot agricultural tools made of scrap bronze. Radiocarbon dating of brushwood from the ship gives an approximate date of 1200 BC.
Composition and microstructure
Typically the copper oxhide ingots are highly pure (approximately 99 weight percent copper) with trace element content of less than one weight percent. The few tin oxhide ingots that have been available to study are also exceptionally pure. Microscopic analysis of the Uluburun copper oxhide ingots reveals that they are highly porous. This feature results from the effervescence of gases as the molten metal cooled. Slag inclusions are also present. Their existence implies that slag was not fully removed from the smelted metal and thus that the ingots were made from remelted copper.
Macroscopic observation of the Uluburun copper ingots indicates that they were cast through multiple pours; there are distinct layers of metal in each ingot. Furthermore, the relatively high weight and high purity of the ingots would be difficult to achieve even today in only one pour.
The porosity of the copper ingots and the natural brittleness of tin suggest that both metal ingots were easy to break. As Bass et al. proposes, a metalsmith could simply break off a piece of the ingot whenever he liked for a new casting.
Provenance
Controversy has swirled around the provenance of the copper oxhide ingots. Lead isotope analysis (LIA) suggests that the late LBA ingots (that is, after 1250 BC) are composed of Cypriot copper, specifically copper from the Apilki mine and its surrounding area. The Gelidonya ingots' ratios are consistent with Cypriot ores while the Uluburun ingots fall on the periphery of the Cypriot isotopic field. On the other hand, Late Minoan I ingots found on Crete have Paleozoic lead isotope ratios and are more consistent with ore sources in Afghanistan, Iran, or Central Asia. The controversy settles on the validity of LIA. Paul Budd argues that LBA copper is the product of such extensive mixing and recycling that LIA, which works best for metals from a single ore deposit, is unfeasible.
Some scholars worry that the 1250 BC date is too limiting. They note that Cyprus was smelting copper on a large scale in the early LBA and had the potential to export the metal to Crete and other places at this time. Furthermore, copper ore is more plentiful on Cyprus than on Sardinia and far more plentiful than on Crete. Archaeologists have discovered numerous Cypriot exports to Sardinia including metalworking tools and prestige metal objects.
Due to the heavy corrosion of tin oxhide ingots and the limited data for lead isotopic studies of tin, the provenance of the tin ingots has been uncertain. The fact that scholars have been unable to pinpoint Bronze Age tin ore deposits compounds this problem.
Molds
A mold for casting an oxhide ingot was discovered in the LBA north palace at Ras Ibn Hani in Syria. It is made of fine-grained "ramleh", a shelly limestone. Archaeologists found burnt copper droplets around the mold. In spite of the questionable durability of limestone, Paul Craddock et al. concluded that limestone can be used for casting “large simple shapes” such as oxhide ingots. Evolution of carbon dioxide from the limestone would damage the metal surface that touched the mold. Thus, metal objects requiring surface detail could not be produced successfully.
This is not to say that oxhide ingots were normally cast in limestone molds. Using an experimental clay mold, Bass et al. argue that the ingot's smooth side was in contact with the mold while its rough side was exposed to the atmosphere. The roughness results from the interaction of the atmosphere and the cooling metal.
Bronze stands with oxhide ingot depictions
In the Late Bronze Age, Cyprus produced numerous bronze stands that depicted a man carrying an oxhide ingot. The stands were designed to hold vases, and they were cast through the lost-wax process. The ingots show the familiar shape of four protruding handles, and the men carry them over their shoulders. These Cypriot stands were exported to Crete and Sardinia, and both islands created similar stands in local bronze workshops.
Egyptian connections
While only one oxhide ingot fragment has been recovered from Egypt (in the context of a LBA smelting workshop), there is a wide array of painted scenes in Egypt that show oxhide ingots. The earliest scene dates to the 15th century BC and the latest scene to the 12th century BC. The ingots display their typical four protrusions, and red paint (which suggests they are copper) is preserved on them. The captions accompanying the scenes explain that the men who bring the ingots come from the north, specifically Retnu (Syria) and Keftiu (unidentified). They are shown being carried on the shoulders of men, sitting with other goods in storage, or as part of scenes in smelting workshops. In a relief from Karnak, the pharaoh Amenhotep II is seen riding a chariot and spearing an oxhide ingot with five arrows. A laudatory caption emphasizing the pharaoh’s strength accompanies the scene.
Several of the “Amarna letters” dating to the mid-14th century BC refer to hundreds of copper talents—in addition to goods such as elephant tusks and glass ingots—sent from the kingdom of Alashiya to Egypt. Some scholars identify Cyprus with Alashiya. In particular, the Uluburun cargo is similar to the goods that, according to the letters, Alashiya sent to Egypt.
References
See Also
Uluburun shipwreck
History of money
External links
Copper ingot in the shape of an oxhide at the British Museum website.
Oxhide ingot found at Enkomi, Cyprus, now in the British Museum
Bronze stand showing oxhide ingot-bearer, found at Kourion, Cyprus, now in the British Museum
Bronze Age
Bronze Age Europe
Archaeological artefact types
History of metallurgy | Oxhide ingot | Chemistry,Materials_science | 2,264 |
3,643,923 | https://en.wikipedia.org/wiki/Electroextraction | Electroextraction (EE) is a sample enrichment technique that focuses charged analytes from a large volume of one phase into a small volume of aqueous phase through the application of an electric current. The technique was originally developed as a separation technique for chemical engineering, but has since been coupled to capillary electrophoresis and liquid chromatography–mass spectrometry as a means of improving limits of detection, analysis time, and selectivity. The use of EE-CE has made capillary electrophoresis more applicable to use in the pharmaceutical industry.
Nomenclature
The term electroextraction is used to describe multiple processes. In this article, electroextraction describes the extraction of charged particles through a liquid phase barrier. The term can be used to describe electrowinning, which is the extraction of metals from their compounds via electrochemical processes. Electroextraction also describes a process of permeating bioproducts from a cell membrane using an electric field.
Applications
Chemical engineering
Johann Stichlmair developed electroextraction at the University of Essen in Germany in 1987 as an improvement on liquid-liquid extraction in an electric field. Electric fields are applied to enhance the demixing of a sample in a two-phase system. However, as current flows through the system, the resulting convective mixing disrupts separation. Electroextraction corrects for this. Two or three liquid phases that are electrically conductive and immiscible with one another are kept between electrodes, and upon addition of an electric field, charged particles travel from one phase to another separating anions and cations. A two-phase system brings anions into one phase and cations into the other. A three phase system extracts anions and cations into the two outer phases while leaving uncharged particles in the middle phase. Convective mixing is restricted to each phase and does not travel between phases. A diagram is given in figure 1. Organic phases that are used typically have small amounts of water added in order to be conductive. Other possible phases include mixtures of water and highly polymerized substances, or water with non-ionic surfactants. Electroextraction has also influenced the development of similar electrophoretic separation techniques involving a membrane between the two-phase systems.
Analytical chemistry
The EE method was first applied to analytical chemistry by Van der Vlis in 1994. A diagram of an electroextraction apparatus is shown in figure 2. The apparatus consists of a vial with a conical bottom, a grounded platinum electrode, a capillary to inject the aqueous solution, and an adjustable gold anode with a circular bottom that contacts the entire organic phase.
EE is also often performed in a capillary electrophoresis capillary. This is referred to as capillary electroextraction, or cEE. In this set up, shown in figure 3, a capillary containing aqueous phase is placed in a vial of organic phase and surrounded by a hallow cathode. The outlet of the capillary is then grounded.
When EE is coupled to isotachophoresis coupled to capillary electrophoresis, limits of detection decrease to the nanomolar range and isotachophoresis takes only a few minutes to complete. Similar limits of detections are obtained when EE is coupled to liquid chromatography-mass spectrometry. Similar limits of detections are obtained when EE is coupled to liquid chromatography-mass spectrometry.
Biomedical
EE is ideal for pharmaceuticals with low concentrations of active ingredient, such as those containing proteins and peptides, because of its ability to lower limits of detection for liquid chromatography and capillary electrophoresis. In addition, sample enrichment by EE helps overcome the low injection volumes and short optical path length of UV-Vis detectors that accompany CE. EE coupled to CE has been used to separate and analyze antisense oligonucleotides. Antisense oligonucleotides inhibit protein expression from their complementary base pair sequence and can treat certain diseases and genetic disorders. EE coupled to liquid chromatography also successfully detects low concentration metabolites in urine for the purpose of studying metabolic processes. In addition, EE-ITP-CE has been used in the determination of the drugs clenbuterol, salbutamol, terbutaline, and fenoterol.
Dyestuffs
Electroextraction has been successfully employed in the separation of dyestuffs from wastewater. Electroextraction is better suited over other techniques for its ability to extract small amounts of dye from very dilute solutions. EE has also been effectively used in the separation of amino acids. This separation was done using an aqueous two-phase system of dextran-polyethylene glycol-water to stabilize the amino acids. The velocity of a particle crossing the phase barrier is directly proportional to the strength of the applied electric field, so 100% separation is achieved with a strong enough field.
References
Liquid-liquid separation | Electroextraction | Chemistry | 1,047 |
71,260,974 | https://en.wikipedia.org/wiki/TZ%20Mensae | TZ Mensae is a binary star in the southern circumpolar constellation Mensa. The system has a combined maximum apparent magnitude of 6.19, placing it near the limit for naked eye visibility. Parallax measurements place the system at a distance of 403 light years. The radial velocity is small.
The components of TZ Mensae have stellar classifications of A0 V and A8 V, both indicating that they are ordinary A-type main-sequence stars. They have masses of , and radii of , respectively. The primary has an effective temperature of and a luminosity 40 times that of the Sun (). As for the companion, it has a temperature of 7,178 K. and a luminosity less than The rotation of both stars is apparently synchronous with the orbital period, with projected rotational velocities of respectively. The system is estimated to be 141 million years old.
The two components take about 8 days to revolve around each other in a relatively circular orbit. Since the inclination is close to (actually ), the two stars periodically pass in front of one another and it has been classified as a eclipsing binary, specifically the Algol type. If the brighter component is eclipsing the dimmer one, the brightness drops to 6.36. If vice versa, it drops to 6.87, which is below the limit for naked eye visibility.
References
Mensa (constellation)
A-type main-sequence stars
Algol variables
Eclipsing binaries
Mensae, TZ
Mensae, 31
CD-84 00063
039780
025776
2059 | TZ Mensae | Astronomy | 341 |
35,811,680 | https://en.wikipedia.org/wiki/Chamonixia%20pachydermis | Chamonixia pachydermis, is a species of fungus in the family Boletaceae, found in New Zealand.
Chamonixia pachydermis is common in areas of New Zealand beech forest and is often partially buried on the ground. It has a blue discoloration.
References
Boletaceae
Fungi of New Zealand
Taxa named by Sanford Myron Zeller
Taxa named by Carroll William Dodge
Fungus species | Chamonixia pachydermis | Biology | 86 |
68,272,140 | https://en.wikipedia.org/wiki/Scientific%20Committee%20on%20Oceanic%20Research | The Scientific Committee on Oceanic Research (SCOR) is an interdisciplinary body of the International Science Council. SCOR was established in 1957, coincident with the International Geophysical Year of 1957-1958. It sought to bring scientists together to answer key ocean science questions and improve opportunities for marginalised scientists.
From 1959 through to 1988 SCOR organised a sequence of Joint Oceanographic Assemblies. Following these, SCOR has focused its efforts on targeted scientific working groups. These small international groups are designed to address narrowly focused scientific topics based on proposals from independent groups of scientists, national committees for SCOR, other scientific organizations, or previous working groups. The working groups last typically for three to four years. SCOR activity, often through the efforts of working groups, has helped support the development of many large-scale ocean research projects.
SCOR-associated programs
IIOE International Indian Ocean Expedition (IIOE) resulted from the first annual SCOR meeting, held at Woods Hole Oceanographic Institution in 1957. The meeting identified the Indian Ocean as the least known component in the global ocean system and so that a campaign of focused observations would be of great benefit. The initiative commenced in 1959 and observational work carried on until 1965.
TOGA the Tropical Ocean-Global Atmosphere Study (TOGA) was coordinated by the World Climate Research Programme (WCRP) and made great observation-based advances in understanding of El Niño and improved skills in predicting the occurrence of El Niño events.
WOCE The World Ocean Circulation Experiment (WOCE) ran from 1990-2002 and aimed to gather more ocean observations in a way that enabled improved modelling tools.
GEOTRACES The GEOTRACES programme was solely sponsored by SCOR and continues to advance knowledge of the oceanic contribution to global biogeochemical cycles of trace elements and their isotopes.
JGOFS The Joint Global Ocean Flux Study focused on the role of the ocean in the global carbon cycle and completed its work in 2003. JGOFS was co-sponsored by SCOR and the International Geosphere-Biosphere Programme (IGBP).
GLOBEC The Global Ocean Ecosystem Dynamics project, completed in 2009, focused on the relationship between physical and biological variability in the ocean and how global change might impact the structure and functioning of marine ecosystems, with particular emphasis on important fisheries. GLOBEC was co-sponsored by SCOR, IGBP, and IOC.
IMBER SCOR and IGBP developed the Integrated Marine Biogeochemistry and Ecosystem Research (IMBER) project that promotes integrated marine research through a range of research topics towards sustainable, productive and healthy oceans at a time of global change, for the benefit of society.
SOLAS Surface Ocean – Lower Atmosphere Study (SOLAS) is sponsored by SCOR, IGBP, the World Climate Research Programme (WCRP) and the Commission on Atmospheric Chemistry and Global Pollution (CACGP). It is global and multidisciplinary in its approach to understanding the key biogeochemical-physical interactions and feedbacks between the ocean and the atmosphere. Additionally, SOLAS seeks to link ocean-atmosphere interactions with climate and people.
GEOHAB Global Ecology and Oceanography of Harmful Algal Blooms project examines the ecological and oceanographic conditions that cause harmful algal blooms and promote their development. It is supported by SCOR and IOC.
IQOE International Quiet Ocean Experiment (co-sponsored by the Partnership for Observation of the Global Oceans) and designed to examine questions around human activities affecting the global ocean soundscape compared with natural changes over geologic time.
IIOE-2 Second International Indian Ocean Expedition (co-sponsored by IOC and the Indian Ocean GOOS program) was a major global scientific program which will engage the international scientific community in collaborative oceanographic and atmospheric research from coastal environments to the deep sea over the period 2015-2020.
SOOS The Southern Ocean Observing System (SOOS) facilitated by both SCOR and the Scientific Committee on Antarctic Research, supports observations, the associated science community and data access, with a focus on the Southern Ocean.
References
International Science Council
Oceanography
Oceanographic organizations
Scientific organizations established in 1957 | Scientific Committee on Oceanic Research | Physics,Environmental_science | 828 |
46,413,558 | https://en.wikipedia.org/wiki/TBX4 | T-box transcription factor Tbx4 is a transcription factor that belongs to T-box gene family that is involved in the regulation of embryonic developmental processes. The transcription factor is encoded by the TBX4 gene located on human chromosome 17. Tbx4 is known mostly for its role in the development of the hindlimb, but it also plays a critical role in the formation of the umbilicus. Tbx4 has been shown to be expressed in the allantois, hindlimb, lung and proctodeum.
Function
Expression of Tbx4 is activated by a combined "caudal" Hox code, expressing a specified positional code that includes Pitx1 gene expression. The encoded protein plays a major role in limb development, specifically during limb bud initiation. For instance, in chickens Tbx4 specifies hindlimb status. The activation of Tbx4 and other T-box proteins by Hox genes activates signaling cascades that involve the Wnt signaling pathway and FGF signals in limb buds. Ultimately, Tbx4 leads to the development of apical ectodermal ridge (AER) and zone of polarizing activity (ZPA) signaling centers in the developing limb bud, which specify the orientation growth of the developing limb. Together with Tbx5, Tbx4 plays a role in patterning the soft tissues (muscles and tendons) of the musculoskeletal system.
Role in non-human animals
In zebrafish, mutations in the nuclear localisation signal of Tbx4 results in the lack of pelvic fin structures, which are homologous to tetrapod hindlimbs.
Mutations
Duplication of the 17q23.1–q23.2 region, which includes the TBX4 gene, has been reported to result in congenital clubfoot. TBX4 duplication within this region has been determined to be the gene that leads to this phenotype.
Loss-of-function TBX4 mutations lead to an autosomal-dominant disorder called small patella syndrome, also known as Scott-Taor syndrome, which is characterized by patellar aplasia and abnormalities of the pelvis and feet. The loss of both parental copies of TBX4, resulting in a complete knockout, was reported by Bruno Reversade and colleagues to result in the total loss of hind limbs in human fetuses. This fatal syndrome is known as posterior amelia with pelvic and pulmonary hypoplasia syndrome (PAPPAS).
Mutations in the TBX4 that cause small patella syndrome are also associated with childhood-onset pulmonary arterial hypertension (PAH). Deletion of 17q23.2 (which includes the TBX4 gene) or a point mutation in the TBX4 gene is reported in 30% of patients with childhood-onset PAH, whereas TBX4 gene mutations are associated with low frequency in adult-onset PAH patients (2%).
Using targeted mutagenesis of Tbx4 in the mouse, various abnormalities were observed in the development of the allantois. Choirioallantoic fusion fails to occur in embryos with the homozygous null allele resulting in death 10.5 days post coitus, embryos with the Tbx4-mutant gene were observed to have allantoises that were apoptotic, stunted, and displayed abnormal differentiation with endothelial cells resulting in the absence of vascular remodeling.
Role
Tbx4 is a transcription factor and member of the T-box family, which have been shown to play important role in fetal development. Tbx4 is expressed in a wide variety of tissues during organogenesis, including the hindlimb, proctodeum, mandibular mesenchyme, lung mesenchyme, atrium of the heart and the body wall. Tbx4 is specifically expressed in the visceral mesoderm of the lung primordium and governs multiple processes during respiratory tract development such as initial endodermal bud development, respiratory endoderm formation, and septation of the respiratory tract and esophagus. Along with Tbx4, Tbx5 is also expressed to help with development of limbs. Tbx4 is expressed in the hindlimb, whereas Tbx5 is expressed in the forelimb, heart, and dorsal side of the retina. Studies have shown that fibroblast growth factor (FGF) play a key role in limb initiation. In a developing embryo a gradient of retinoic acid aids in the combinatorial patterns of Hox gene expression along the body axis, which causes regions of the paraxial mesoderm to emit a signal to the lateral mesoderm that causes the expression of Tbx4 and Tbx5. When these two molecules are expressed that stimulate the secretion of FGF-10, which will induce the ectoderm to produce FGF-8. FGF-8 and FGF-10 together promote limb development. Mutations or teratogens that interfere with Tbx4/Tbx5 or FGF-8/FGF-10 has the ability to cause a child to be born without one or more limbs. A common syndrome seen with a mutation these genes is Tetra-Amelia syndrome which is characterized by the absence of all four limbs and anomalies involving the cranium and the face; eyes; urogenital system; heart; lungs and central nervous system. In a study done by Naiche et al. they generated a knockout mouse in which it lacked the expression on Tbx4 this mouse resulted in a phenotype of no limb formation.
References
Transcription factors | TBX4 | Chemistry,Biology | 1,173 |
675,364 | https://en.wikipedia.org/wiki/Voltage%20regulation | In electrical engineering, particularly power engineering, voltage regulation is a measure of change in the voltage magnitude between the sending and receiving end of a component, such as a transmission or distribution line. Voltage regulation describes the ability of a system to provide near constant voltage over a wide range of load conditions. The term may refer to a passive property that results in more or less voltage drop under various load conditions, or to the active intervention with devices for the specific purpose of adjusting voltage.
Electrical power systems
In electrical power systems, voltage regulation is a dimensionless quantity defined at the receiving end of a transmission line as:
where
Vnl is voltage at no load and Vfl is voltage at full load. The percent voltage regulation of an ideal transmission line, as defined by a transmission line with zero resistance and reactance, would equal zero due to Vnl equaling Vfl as a result of there being no voltage drop along the line. This is why a smaller value of Voltage Regulation is usually beneficial, indicating that the line is closer to ideal.
The Voltage Regulation formula could be visualized with the following: "Consider power being delivered to a load such that the voltage at the load is the load's rated voltage VRated, if then the load disappears, the voltage at the point of the load will rise to Vnl."
Voltage regulation in transmission lines occurs due to the impedance of the line between its sending and receiving ends. Transmission lines intrinsically have some amount of resistance, inductance, and capacitance that all change the voltage continuously along the line. Both the magnitude and phase angle of voltage change along a real transmission line. The effects of line impedance can be modeled with simplified circuits such as the short line approximation (least accurate), the medium line approximation (more accurate), and the long line approximation (most accurate).
The short line approximation ignores capacitance of the transmission line and models the resistance and reactance of the transmission line as a simple series resistor and inductor. This combination has impedance R + jωL or R + jX. There is a single line current I = IS = IR in the short line approximation, different from the medium and long line. The medium length line approximation takes into account the shunt admittance, usually pure capacitance, by distributing half the admittance at the sending and receiving end of the line. This configuration is often referred to as a nominal - π. The long line approximation takes these lumped impedance and admittance values and distributes them uniformly along the length of the line. The long line approximation therefore requires the solving of differential equations and results in the highest degree of accuracy.
In the voltage regulation formula, Vno load is the voltage measured at the receiving end terminals when the receiving end is an open circuit. The entire short line model is an open circuit in this condition, and no current flows in an open circuit, so I = 0 A and the voltage drop across the line given by Ohm’s law Vline drop = IZline is 0 V. The sending and receiving end voltages are thus the same. This value is what the voltage at the receiving end would be if the transmission line had no impedance. The voltage would not be changed at all by the line, which is an ideal scenario in power transmission.
Vfull load is the voltage across the load at the receiving end when the load is connected and current flows in the transmission line. Now Vline drop = IZline is nonzero, so the voltages and the sending and receiving ends of the transmission line are not equal. The current I can be found by solving Ohm’s law using a combined line and load impedance: . Then the VR, full load is given by .
The effects of this modulation on voltage magnitude and phase angle is illustrated using phasor diagrams that map VR, VS, and the resistive and inductive components of Vline drop. Three power factor scenarios are shown, where (a) the line serves an inductive load so the current lags receiving end voltage, (b) the line serves a completely real load so the current and receiving end voltage are in phase, and (c) the line serves a capacitive load so the current leads receiving end voltage. In all cases the line resistance R causes a voltage drop that is in phase with current, and the reactance of the line X causes a voltage drop that leads current by 90 degrees. These successive voltage drops are summed to the receiving end voltage, tracing backward from VR to VS in the short line approximation circuit. The vector sum of VR and the voltage drops equals VS, and it is apparent in the diagrams that VS does not equal VR in magnitude or phase angle.
The diagrams show that the phase angle of current in the line affects voltage regulation significantly. Lagging current in (a) makes the required magnitude of sending end voltage quite large relative to the receiving end. The phase angle difference between sending and receiving end is minimized, however. Leading current in (c) actually allows the sending end voltage magnitude be smaller than the receiving end magnitude, so the voltage counterintuitively increases along the line. In-phase current in (b) does little to affect the magnitude of voltage between sending and receiving ends, but the phase angle shifts considerably.
Real transmission lines typically serve inductive loads, which are the motors that exist everywhere in modern electronics and machines. Transferring a large amount of reactive power Q to inductive loads makes the line current lag voltage, and the voltage regulation is characterized by decrease in voltage magnitude. In transferring a large amount of real power P to real loads, current is mostly in phase with voltage. The voltage regulation in this scenario is characterized by a decrease in phase angle rather than magnitude.
Sometimes, the term voltage regulation is used to describe processes by which the quantity VR is reduced, especially concerning special circuits and devices for this purpose (see below).
Electronic power supply parameters
The quality of a system's voltage regulation is described by three main parameters:
Distribution feeder regulation
Electric utilities aim to provide service to customers at a specific voltage level, for example, 220 V or 240 V. However, due to Kirchhoff's Laws, the voltage magnitude and thus the service voltage to customers will in fact vary along the length of a conductor such as a distribution feeder (see Electric power distribution). Depending on law and local practice, actual service voltage within a tolerance band such as ±5% or ±10% may be considered acceptable. In order to maintain voltage within tolerance under changing load conditions, various types of devices are traditionally employed:
a load tap changer (LTC) at the substation transformer, which changes the turns ratio in response to load current and thereby adjusts the voltage supplied at the sending end of the feeder;
voltage regulators, which are essentially transformers with tap changers to adjust the voltage along the feeder, so as to compensate for the voltage drop over distance; and
capacitors, which reduce the voltage drop along the feeder by reducing current flow to loads consuming reactive power.
A new generation of devices for voltage regulation based on solid-state technology are in the early commercialization stages.
Distribution regulation involves a "regulation point": the point at which the equipment tries to maintain constant voltage. Customers further than this point observe an expected effect: higher voltage at light load, and lower voltage at high load. Customers closer than this point experience the opposite effect: higher voltage at high load, and lower voltage at light load.
Complications due to distributed generation
Distributed generation, in particular photovoltaics connected at the distribution level, presents a number of significant challenges for voltage regulation.
Conventional voltage regulation equipment works under the assumption that line voltage changes predictably with distance along the feeder. Specifically, feeder voltage drops with increasing distance from the substation due to line impedance and the rate of voltage drop decreases farther away from the substation. However, this assumption may not hold when DG is present. For example, a long feeder with a high concentration of DG at the end will experience significant current injection at points where the voltage is normally lowest. If the load is sufficiently low, current will flow in the reverse direction (i.e. towards the substation), resulting in a voltage profile that increases with distance from the substation. This inverted voltage profile may confuse conventional controls. In one such scenario, load tap changers expecting voltage to decrease with distance from the substation may choose an operating point that in fact causes voltage down the line to exceed operating limits.
The voltage regulation issues caused by DG at the distribution level are complicated by lack of utility monitoring equipment along distribution feeders. The relative scarcity of information on distribution voltages and loads makes it difficult for utilities to make adjustments necessary to keep voltage levels within operating limits.
Although DG poses a number of significant challenges for distribution level voltage regulation, if combined with intelligent power electronics DG can actually serve to enhance voltage regulation efforts. One such example is PV connected to the grid through inverters with volt-VAR control. In a study conducted jointly by the National Renewable Energy Laboratory (NREL) and Electric Power Research Institute (EPRI), when volt-VAR control was added to a distribution feeder with 20% PV penetration, the diurnal voltage swings on the feeder were significantly reduced.
Transformers
One case of voltage regulation is in a transformer. The unideal components of the transformer cause a change in voltage when current flows. Under no load, when no current flows through the secondary coils, Vnl is given by the ideal model, where VS = VP*NS/NP. Looking at the equivalent circuit and neglecting the shunt components, as is a reasonable approximation, one can refer all resistance and reactance to the secondary side and clearly see that the secondary voltage at no load will indeed be given by the ideal model. In contrast, when the transformer delivers full load, a voltage drop occurs over the winding resistance, causing the terminal voltage across the load to be lower than anticipated. By the definition above, this leads to a nonzero voltage regulation which must be considered in use of the transformer.
See also
Voltage regulator
Electric power distribution
Shunt regulator
References | Voltage regulation | Physics | 2,084 |
859,830 | https://en.wikipedia.org/wiki/Eduard%20%C4%8Cech | Eduard Čech (; 29 June 1893 – 15 March 1960) was a Czech mathematician. His research interests included projective differential geometry and topology. He is especially known for the technique known as Stone–Čech compactification (in topology) and the notion of Čech cohomology. He was the first to publish a proof of Tychonoff's theorem in 1937.
Biography
He was born in Stračov, then in Bohemia, Austria-Hungary, now in the Czech Republic. His father was Čeněk Čech, a policeman, and his mother was Anna Kleplová.
After attending the gymnasium in Hradec Králové, Čech was admitted to the Philosophy Faculty of Charles University of Prague in 1912. In 1915 he was drafted into the Austro-Hungarian Army and participated in World War I, after which he completed his undergraduate degree in 1918. He received his doctoral degree in 1920 at Charles University; his thesis, titled On Curves and Plane Elements of the Third Order, was written under the direction of Karel Petr. In 1921–1922 he collaborated with Guido Fubini in Turin, Italy. He taught at Masaryk University in Brno and at Charles University. Ivo Babuška, Vlastimil Dlab, Zdeněk Frolík, Věra Trnková, and Petr Vopěnka have been doctoral students of Čech.
He attended the First International Topological Conference held in Moscow 4–10 September 1935. He made two presentations there: "Accessibility and homology" and "Betti groups with different coefficient groups".
He died in Prague in 1960.
Publications
See also
Čech closure operator
Čech cohomology
Čech nerve
Stone–Čech compactification
Tychonoff's theorem
References
External links
List of publications from Czech Digital Mathematics Library
1893 births
1960 deaths
People from Hradec Králové District
People from the Kingdom of Bohemia
Czech mathematicians
20th-century Czech mathematicians
Topologists
Charles University alumni
Institute for Advanced Study visiting scholars
Academic staff of Masaryk University
Academic staff of Charles University
Austro-Hungarian military personnel of World War I | Eduard Čech | Mathematics | 423 |
6,779,384 | https://en.wikipedia.org/wiki/Hexapod%20%28robotics%29 | A six-legged walking robot should not be confused with a Stewart platform, a kind of parallel manipulator used in robotics applications.
A hexapod robot is a mechanical vehicle that walks on six legs. Since a robot can be statically stable on three or more legs, a hexapod robot has a great deal of flexibility in how it can move. If legs become disabled, the robot may still be able to walk. Furthermore, not all of the robot's legs are needed for stability; other legs are free to reach new foot placements or manipulate a payload.
Many hexapod robots are biologically inspired by Hexapoda locomotion – the insectoid robots. Hexapods may be used to test biological theories about insect locomotion, motor control, and neurobiology.
Designs
Hexapod designs vary in leg arrangement. Insect-inspired robots are typically laterally symmetric, such as the RiSE robot at Carnegie Mellon. A radially symmetric hexapod is ATHLETE (All-Terrain Hex-Legged Extra-Terrestrial Explorer) robot at JPL.
Typically, individual legs range from two to six degrees of freedom. Hexapod feet are typically pointed, but can also be tipped with adhesive material to help climb walls or wheels so the robot can drive quickly when the ground is flat.
Locomotion
Most often, hexapods are controlled by gaits, which allow the robot to move forward, turn, and perhaps side-step. Some of the
most common gaits are as follows:
Alternating tripod: 3 legs on the ground at a time.
Quadruped.
Crawl: move just one leg at a time.
Gaits for hexapods are often stable, even in slightly rocky and uneven terrain.
Motion may also be nongaited, which means the sequence of leg motions is not fixed, but rather chosen by the computer in response to the sensed environment. This may be most helpful in very rocky terrain, but existing techniques for motion planning are computationally expensive.
Biologically inspired
Insects are chosen as models because their nervous system are simpler than other animal species. Also, complex behaviours can be attributed to just a few neurons and the pathway between sensory input and motor output is relatively shorter. Insects' walking behaviour and neural architecture are used to improve robot locomotion. Conversely, biologists can use hexapod robots for testing different hypotheses.
Biologically inspired hexapod robots largely depend on the insect species used as a model. The cockroach and the stick insect are the two most commonly used insect species; both have been ethologically and neurophysiologically extensively studied. At present no complete nervous system is known, therefore, models usually combine different insect models, including those of other insects.
Insect gaits are usually obtained by two approaches: the centralized and the decentralized control architectures. Centralized controllers directly specify transitions of all legs, whereas in decentralized architectures, six nodes (legs) are connected in a parallel network; gaits arise by the interaction between neighbouring legs.
List of robots
Hexbug (insectoid toy robot)
Stiquito (inexpensive insectoid robot)
Rhex
Whegs
LAURON
See also
Biomechanics
Insects
Mondo spider
Robotics
Robot locomotion
Stewart platform
References
External links
Poly-pedal Laboratory at Berkeley (USA).
Biological Cybernetics/Theoretical Biology (Germany).
Robot kinematics
Robot locomotion | Hexapod (robotics) | Physics,Engineering | 706 |
1,756,887 | https://en.wikipedia.org/wiki/Salginatobel%20Bridge | Salginatobel Bridge is a reinforced concrete arch bridge designed by Swiss civil engineer Robert Maillart. It was constructed across an alpine ravine in the grisonian Prättigau, belonging to the municipality of Schiers, in Switzerland between 1929 and 1930. In 1991, it was declared an International Historic Civil Engineering Landmark, the thirteenth such structure and the first concrete bridge so designated.
As with his Schwandbach Bridge and Vessy Bridge, the structure's fame among civil engineers is a consequence of the techniques involved and the elegance of its design rather than its prominent location: it connects the village Schiers – on valley floor of the route between Landquart and Davos – with the alpine hamlet Schuders of almost 100 people, where the alpine post road ends, but is often visited by designers.
Design and history
Maillart had previously designed a three-hinged arch bridge over the Rhine at Tavanasa in 1904. In the span Tavanasa bridge, the arch is thinnest at its crown and springing points, thickening in between to reflect the shape of its bending moment diagram. This bridge was destroyed by an avalanche in September 1927. Although Maillart didn't win the contract for a replacement bridge, he entered a competition the following year for the bridge at Salginatobel, with a three-hinged arch spanning that used the same overall form as at Tavanasa. In conjunction with contractor Florian Prader, Maillart's design was the least expensive of nineteen entries.
The Salginatobel bridge arch is long in total, and its main element is a hollow concrete box girder over the central part of the arch. It carries a roadway wide, supported on reinforced concrete pillars above the ends of the arches.
The falsework was built by the Graubünden carpenter Richard Coray in late summer 1929, and the rest of the construction started in 1930. The bridge was officially opened on 18 August 1930.
Although regarded as a pioneering work, several aspects of its construction lacked durability, such as the absence of bridge deck waterproofing, low concrete cover and poor drainage. In 1975 and 1976 it was extensively repaired, the parapets were modified, and waterproofing was added. However, by 1991, deterioration had continued, with the parapets becoming unsafe. The waterproofing and drainage were replaced and amended, and most of the existing concrete surface removed and replaced by shotcrete. The parapets were completely rebuilt. Completed in 1998, this repair work cost 1.3 million US dollars.
Praise and criticism
1947, the bridge was featured with other of Maillart's works in a four-month exhibit at the Museum of Modern Art, New York
Salginatobel Bridge was designated a Swiss heritage site of national significance.
1991, it was designated an International Historic Civil Engineering Landmark by the American Society of Civil Engineers
The bridge has received widespread attention since its innovative design and construction, including considerable praise from other bridge engineers, architects and architectural historians. Writing in 2000, Heinrich Figi said:
David P. Billington has been particularly enthusiastic about the bridge:
The German bridge engineer Fritz Leonhardt has suggested that:
Maillart was not entirely satisfied with the bridge, writing after its completion that its soffit should have been a pointed rather than a pure curved arch, if it were properly to match his structural analysis:
Image gallery
References
ASCE page on the bridge
Billington, David P. Maillart and the Salginatobel Bridge. Structural Engineering International, 1/1991.
Billington, David P. The Tower and the Bridge. Princeton University Press, Princeton, USA, 1983.
Billington, David P. Robert Maillart and the Art of Reinforced Concrete. The MIT Press. Cambridge, USA, 1990. .
Billington, David P. The Art of Structural Design: A Swiss Legacy. Princeton University Art Museum. Princeton, USA, 2003. .
Figi, Heinrich. Rehabilitation of the Salginatobel Bridge. Structural Engineering International, 1/2000.
Leonhardt, Fritz. Bridges: Aesthetics and Design. The MIT Press, Cambridge, USA, 1984.
Maillart, Robert. Construction and Aesthetic of Bridges. The Concrete Way, May–June 1935.
Notes
External links
(includes construction photo)
ASCE: Salginatobel Bridge
Great Buildings Online
Sightseeing Graubünden, Switzerland, official tourism board suggestions and location
Deck arch bridges
Bridges completed in 1930
Road bridges in Switzerland
Monuments and memorials in Switzerland
Historic Civil Engineering Landmarks
Concrete bridges
Schiers
20th-century architecture in Switzerland
Bridges in Graubunden | Salginatobel Bridge | Engineering | 941 |
70,210,267 | https://en.wikipedia.org/wiki/Arithmetic%20progression%20topologies | In general topology and number theory, branches of mathematics, one can define various topologies on the set of integers or the set of positive integers by taking as a base a suitable collection of arithmetic progressions, sequences of the form or The open sets will then be unions of arithmetic progressions in the collection. Three examples are the Furstenberg topology on , and the Golomb topology and the Kirch topology on . Precise definitions are given below.
Hillel Furstenberg introduced the first topology in order to provide a "topological" proof of the infinitude of the set of primes. The second topology was studied by Solomon Golomb and provides an example of a countably infinite Hausdorff space that is connected. The third topology, introduced by A.M. Kirch, is an example of a countably infinite Hausdorff space that is both connected and locally connected. These topologies also have interesting separation and homogeneity properties.
The notion of an arithmetic progression topology can be generalized to arbitrary Dedekind domains.
Construction
Two-sided arithmetic progressions in are subsets of the form
where and The intersection of two such arithmetic progressions is either empty, or is another arithmetic progression of the same form:
where is the least common multiple of and
Similarly, one-sided arithmetic progressions in are subsets of the form
with and . The intersection of two such arithmetic progressions is either empty, or is another arithmetic progression of the same form:
with equal to the smallest element in the intersection.
This shows that every nonempty intersection of a finite number of arithmetic progressions is again an arithmetic progression. One can then define a topology on or by choosing a collection of arithmetic progressions, declaring all elements of to be open sets, and taking the topology generated by those. If any nonempty intersection of two elements of is again an element of , the collection will be a base for the topology. In general, it will be a subbase for the topology, and the set of all arithmetic progressions that are nonempty finite intersections of elements of will be a base for the topology. Three special cases follow.
The Furstenberg topology, or evenly spaced integer topology, on the set of integers is obtained by taking as a base the collection of all with and
The Golomb topology, or relatively prime integer topology, on the set of positive integers is obtained by taking as a base the collection of all with and and relatively prime. Equivalently, the subcollection of such sets with the extra condition also forms a base for the topology. The corresponding topological space is called the Golomb space.
The Kirch topology, or prime integer topology, on the set of positive integers is obtained by taking as a subbase the collection of all with and prime not dividing
Equivalently, one can take as a subbase the collection of all with prime and . A base for the topology consists of all with relatively prime and squarefree (or the same with the additional condition ). The corresponding topological space is called the Kirch space.
The three topologies are related in the sense that every open set in the Kirch topology is open in the Golomb topology, and every open set in the Golomb topology is open in the Furstenberg topology (restricted to the subspace ). On the set , the Kirch topology is coarser than the Golomb topology, which is itself coarser that the Furstenberg topology.
Properties
The Golomb topology and the Kirch topology are Hausdorff, but not regular.
The Furstenberg topology is Hausdorff and regular. It is metrizable, but not completely metrizable. Indeed, it is homeomorphic to the rational numbers with the subspace topology inherited from the real line. Broughan has shown that the Furstenberg topology is closely related to the -adic completion of the rational numbers.
Regarding connectedness properties, the Furstenberg topology is totally disconnected. The Golomb topology is connected, but not locally connected. The Kirch topology is both connected and locally connected.
The integers with the Furstenberg topology form a homogeneous space, because it is a topological ring — in some sense, the only topology on for which it is a ring. By contrast, the Golomb space and the Kirch space are topologically rigid — the only self-homeomorphism is the trivial one.
Relation to the infinitude of primes
Both the Furstenberg and Golomb topologies furnish a proof that there are infinitely many prime numbers. A sketch of the proof runs as follows:
Fix a prime and note that the (positive, in the Golomb space case) integers are a union of finitely many residue classes modulo . Each residue class is an arithmetic progression, and thus clopen.
Consider the multiples of each prime. These multiples are a residue class (so closed), and the union of these sets is all (Golomb: positive) integers except the units .
If there are finitely many primes, that union is a closed set, and so its complement (}) is open.
But every nonempty open set is infinite, so } is not open.
Generalizations
The Furstenberg topology is a special case of the profinite topology on a group. In detail, it is the topology induced by the inclusion , where is the profinite integer ring with its profinite topology.
The notion of an arithmetic progression makes sense in arbitrary -modules, but the construction of a topology on them relies on closure under intersection. Instead, the correct generalization builds a topology out of ideals of a Dedekind domain. This procedure produces a large number of countably infinite, Hausdorff, connected sets, but whether different Dedekind domains can produce homeomorphic topological spaces is a topic of current research.
Notes
References
.
Topological spaces
Arithmetic series | Arithmetic progression topologies | Mathematics | 1,204 |
8,958 | https://en.wikipedia.org/wiki/Dunstan | Dunstan ( – 19 May 988), was an English bishop and Benedictine monk. He was successively Abbot of Glastonbury Abbey, Bishop of Worcester, Bishop of London and Archbishop of Canterbury, later canonised. His work restored monastic life in England and reformed the English Church. His 11th-century biographer Osbern, himself an artist and scribe, states that Dunstan was skilled in "making a picture and forming letters", as were other clergy of his age who reached senior rank.
Dunstan served as an important minister of state to several English kings. He was the most popular saint in England for nearly two centuries, having gained fame for the many stories of his greatness, not least among which were those concerning his famed cunning in defeating the Devil.
Early life (909–943)
Birth and relatives
According to Dunstan's earliest biographer, known only as 'B', his parents were called Heorstan and Cynethryth and they lived near Glastonbury. B states that Dunstan was "oritur" in the days of King Æthelstan, 924 to 939. "Oritur" has often been taken to mean "born", but this is unlikely as another source states that he was ordained during Æthelstan's reign, and he would have been under the minimum age of 30 if he was born no earlier than 924. It is more likely that "oritur" should be taken as "emerged" and that he was born around 910. B states that he was related to Ælfheah the Bald, the Bishop of Winchester and Cynesige, Bishop of Lichfield. According to a later biographer, Adelard of Ghent, he was a nephew of Athelm, Archbishop of Canterbury, but this is less certain as it is not mentioned by B, who should have known as he had been a member of Dunstan's household.
School to the king's court
As a young boy, Dunstan studied under the Irish monks who then occupied the ruins of Glastonbury Abbey. Accounts tell of his youthful optimism and of his vision of the abbey being restored. While still a boy, Dunstan was stricken with a near-fatal illness and effected a seemingly miraculous recovery. Even as a child, he was noted for his devotion to learning and for his mastery of many kinds of artistic craftsmanship. With his parents' consent he was tonsured, received minor orders and served in the ancient church of St Mary. He became so well known for his devotion to learning that he is said to have been summoned by Athelm to enter his service. He was later appointed to the court of King Æthelstan.
Dunstan soon became a favourite of the king and was the envy of other members of the court. A plot was hatched to disgrace him and Dunstan was accused of being involved with witchcraft and black magic. The king ordered him to leave the court and as Dunstan was leaving the palace his enemies physically attacked him, beat him severely, bound him, and threw him into a cesspool. He managed to crawl out and make his way to the house of a friend. From there, he journeyed to Winchester and entered the service of his kinsman Ælfheah, Bishop of Winchester.
The bishop tried to persuade him to become a monk, but Dunstan was doubtful whether he had a vocation to a celibate life. The answer came in the form of an attack of swelling tumours all over Dunstan's body. This ailment was so severe that it was thought to be leprosy. It was more probably some form of blood poisoning caused by being beaten and thrown in the cesspool. Whatever the cause, it changed Dunstan's mind. He took Holy Orders in 943, in the presence of Ælfheah, and returned to live the life of a hermit at Glastonbury. Against the old church of St Mary he built a small cell long and deep. It was there that Dunstan studied, worked at his art, and played on his harp. It is at this time, according to a late 11th-century legend, that the Devil is said to have tempted Dunstan and to have been held by the face with Dunstan's tongs.
Monk and abbot (943–957)
Life as a monk
Dunstan worked as a silversmith and in the scriptorium while he was living at Glastonbury. It is thought likely that he was the artist who drew the well-known image of Christ with a small kneeling monk beside him in the Glastonbury Classbook, "one of the first of a series of outline drawings which were to become a special feature of Anglo-Saxon art of this period." Dunstan became famous as a musician, illuminator, and metalworker. Lady Æthelflæd, King Æthelstan's niece, made Dunstan a trusted adviser and on her death, she left a considerable fortune to him. He used this money later in life to foster and encourage a monastic revival in England. About the same time, his father Heorstan died and Dunstan inherited his fortune as well. He became a person of great influence, and on the death of King Æthelstan in 940, the new King, Edmund, summoned him to his court at Cheddar and made him a minister.
Again, royal favour fostered jealousy among other courtiers and again Dunstan's enemies succeeded in their plots. The King was prepared to send Dunstan away. There were then at Cheddar certain envoys from the "Eastern Kingdom", which probably meant East Anglia. Dunstan implored the envoys to take him with them when they returned to their homes. They agreed to do so, but it never happened. The story is recorded:
Abbot of Glastonbury
Dunstan, now Abbot of Glastonbury, went to work at once on the task of reform. He had to re-create monastic life and to rebuild the abbey. He began by establishing Benedictine monasticism at Glastonbury. The Rule of St. Benedict was the basis of his restoration according to the author of 'Edgar's Establishment of the Monasteries' (written in the 960s or 970s) and according to Dunstan's first biographer, who had been a member of the community at Glastonbury. Their statements are also in accordance with the nature of his first measures as abbot, with the significance of his first buildings, and with the Benedictine leanings of his most prominent disciples.
Nevertheless, not all the members of Dunstan's community at Glastonbury were monks who followed the Benedictine Rule. In fact, Dunstan's first biographer, 'B.', was a cleric who eventually joined a community of canons at Liège after leaving Glastonbury.
Dunstan's first care was to rebuild the Church of St. Peter, rebuild the cloister, and re-establish the monastic enclosure. The secular affairs of the house were committed to his brother, Wulfric, "so that neither himself nor any of the professed monks might break enclosure." A school for the local youth was founded and soon became the most famous of its time in England. A substantial extension of the irrigation system on the surrounding Somerset Levels was also completed.
Within two years of Dunstan's appointment, in 946, King Edmund was assassinated. His successor was Eadred. The policy of the new government was supported by the Queen mother, Eadgifu of Kent, by the Archbishop of Canterbury, Oda, and by the East Anglian nobles, at whose head was the powerful ealdorman Æthelstan the "Half-king". It was a policy of unification and conciliation with the Danish half of the kingdom. The goal was a firm establishment of royal authority. In ecclesiastical matters it favoured the spread of Catholic observance, the rebuilding of churches, the moral reform of the clergy and laity, and the end of the religion of the Danes in England. These policies made Dunstan popular in the North of England, but unpopular in the South. Against all these reforms were the nobles of Wessex, who included most of Dunstan's own relatives, and who had an interest in maintaining established customs. For nine years Dunstan's influence was dominant, during which time he twice refused the office of bishop (that of Winchester in 951 and Crediton in 953), affirming that he would not leave the king's side so long as the king lived and needed him.
Changes in fortune
In 955, Eadred died, and the situation was at once changed. Eadwig, the elder son of Edmund, who then came to the throne, was a headstrong youth wholly devoted to the reactionary nobles. According to one legend, the feud with Dunstan began on the day of Eadwig's coronation, when he failed to attend a meeting of nobles. When Dunstan eventually found the young monarch, he was cavorting with a noblewoman named Ælfgifu and her mother, and refused to return with the bishop. Infuriated by this, Dunstan dragged Eadwig back to the royal gathering.
Later realising that he had provoked the king, Dunstan saw that his life was in danger. He fled England and crossed the channel to Flanders, where he found himself ignorant of the language and of the customs of the locals. The count of Flanders, Arnulf I, received him with honour and lodged him in the Abbey of Mont Blandin, near Ghent. This was one of the centres of the Benedictine revival in that country, and Dunstan was able for the first time to observe the strict observance that had seen its rebirth at Cluny at the beginning of the century. His exile was not of long duration. Before the end of 957, the Mercians and Northumbrians revolted and drove out Eadwig, choosing his brother Edgar as king of the country north of the Thames. The south remained faithful to Eadwig. At once Edgar's advisers recalled Dunstan.
Bishop and archbishop (957–978)
Bishop of Worcester and of London
On Dunstan's return, Archbishop Oda consecrated him a bishop and, on the death of Coenwald of Worcester at the end of 957, Oda appointed Dunstan to the see.
In the following year the see of London became vacant and was conferred on Dunstan, who held it simultaneously with Worcester. In October 959, Eadwig died and his brother Edgar was readily accepted as ruler of Wessex. One of Eadwig's final acts had been to appoint a successor to Archbishop Oda, who died on 2 June 958. The chosen candidate was Ælfsige of Winchester, but he died of cold in the Alps as he journeyed to Rome for the pallium. In his place Eadwig then nominated one of his supporters, the Bishop of Wells, Byrhthelm. As soon as Edgar became king, he reversed this second choice on the ground that Byrhthelm had not been able to govern even his first diocese properly. The archbishopric was then conferred on Dunstan.
Archbishop of Canterbury
Dunstan went to Rome in 960, and received the pallium from Pope John XII. On his journey there, Dunstan's acts of charity were so lavish as to leave nothing for himself and his attendants. His steward complained, but Dunstan seems to have suggested that they trust in Jesus Christ.
On his return from Rome, Dunstan at once regained his position as virtual prime minister of the kingdom. By his advice Ælfstan was appointed to the Bishopric of London, and Oswald to that of Worcester. In 963, Æthelwold, the Abbot of Abingdon, was appointed to the See of Winchester. With their aid and with the ready support of King Edgar, Dunstan pushed forward his reforms in the English Church. The monks in his communities were taught to live in a spirit of self-sacrifice, and Dunstan actively enforced the law of celibacy whenever possible. He forbade the practices of simony (selling ecclesiastical offices for money) and ended the custom of clerics appointing relatives to offices under their jurisdiction. Monasteries were built, and in some of the great cathedrals, monks took the place of the secular canons; in the rest the canons were obliged to live according to rule. The parish priests were compelled to be qualified for their office; they were urged to teach parishioners not only the truths of the Christian faith, but also trades to improve their position. The state saw reforms as well. Good order was maintained throughout the realm and there was respect for the law. Trained bands policed the north, and a navy guarded the shores from Viking raids.
In 973, Dunstan's statesmanship reached its zenith when he officiated at the coronation of King Edgar. Edgar was crowned at Bath in an imperial ceremony planned not as the initiation, but as the culmination of his reign (a move that must have taken a great deal of preliminary diplomacy). This service, devised by Dunstan himself and celebrated with a poem in the Anglo-Saxon Chronicle forms the basis of the present-day British coronation ceremony. There was a second symbolic coronation held later. This was an important step, as other kings of Britain came and gave their allegiance to Edgar at Chester. Six kings in Britain, including the kings of Scotland and of Strathclyde, pledged their faith that they would be the king's liege-men on sea and land.
Edgar ruled as a strong and popular king for 16 years. Edgar's reign, and implicitly his governing partnership with Dunstan, was praised by early chroniclers and historians who regarded it as a golden age. The Anglo-Saxon Chronicle caveated the acclaim with one complaint, criticising the high level of immigration that took place at that time. It would appear from William of Malmesbury's later history that the objection was limited to the mercenary seaman, employed from around the North Sea littoral, to assist in the defence of the country.
In 975, Edgar was succeeded by his eldest son Edward "the Martyr". His accession was disputed by his stepmother, Ælfthryth, who wished her own son Æthelred to reign. Through the influence of Dunstan, Edward was chosen and crowned at Winchester. Edgar's death had encouraged the reactionary nobles, and at once there was a determined attack upon the monks, the protagonists of reform. Throughout Mercia they were persecuted and deprived of their possessions. Their cause, however, was supported by Æthelwine, the ealdorman of East Anglia, and the realm was in serious danger of civil war. Three meetings of the Witan were held to settle these disputes, at Kyrtlington, at Calne, and at Amesbury. At the second of them the floor of the hall where the Witan was sitting gave way, and all except Dunstan, who clung to a beam, fell into the room below; several men were killed.
Final years (978–88)
In March 978, King Edward was assassinated at Corfe Castle, possibly at the instigation of his stepmother, and Æthelred the Unready became king. The coronation took place on Low Sunday 31 March 978. According to William of Malmsesbury, writing over a century later, when the young king took the usual oath to govern well, Dunstan addressed him in solemn warning. He criticised the violent act whereby he became king and prophesied the misfortunes that were shortly to fall on the kingdom, but Dunstan's influence at court was ended. Dunstan retired to Canterbury, to teach at the cathedral school.
Only three more public acts are known. In 980, Dunstan joined Ælfhere of Mercia in the solemn translation of the relics of King Edward, soon to be regarded as a saint, from their grave at Wareham to a shrine at Shaftesbury Abbey. In 984, he persuaded King Æthelred to appoint Ælfheah as Bishop of Winchester in succession to Æthelwold. In 986, Dunstan induced the king, by a donation of 100 pounds of silver, to stop his persecution of the See of Rochester.
Dunstan's retirement at Canterbury consisted of long hours, both day and night, spent in private prayer, as well as his regular attendance at Mass and the daily office. He visited the shrines of St Augustine and St Æthelberht. He worked to improve the spiritual and temporal well-being of his people, to build and restore churches, to establish schools, to judge suits, to defend widows and orphans, to promote peace, and to enforce respect for purity. He practised his crafts, made bells and organs and corrected the books in the cathedral library. He encouraged and protected European scholars who came to England, and was active as a teacher of boys in the cathedral school. On Ascension Day 988, Dunstan said Mass and preached three times to the people: at the Gospel, at the benediction, and after the Agnus Dei. In this last address, he announced his impending death and wished his congregation well. That afternoon he chose the spot for his tomb, then went to his bed. His strength failed rapidly, and on Saturday morning, 19 May, he caused the clergy to assemble. Mass was celebrated in his presence, then he received Extreme Unction and the Viaticum, and died. Dunstan's final words are reported to have been, "He hath made a remembrance of his wonderful works, being a merciful and gracious Lord: He hath given food to them that fear Him."
The English people accepted him as a saint shortly thereafter. He was formally canonised in 1029. That year at the Synod of Winchester, St Dunstan's feast was ordered to be kept solemnly throughout England.
Legacy
Until Thomas Becket's fame overshadowed Dunstan's, he was the favourite saint of the English people. Dunstan had been buried in his cathedral. In 1180 his relics were translated to a tomb on the south side of the high altar, when that building was restored after being partially destroyed by a fire in 1174.
The monks of Glastonbury used to claim that during the sack of Canterbury by the Danes in 1012, Dunstan's body had been carried for safety to their abbey. This story was disproved by Archbishop William Warham, who opened the tomb at Canterbury in 1508. They found Dunstan's relics still to be there. However, his shrine was destroyed during the English Reformation.
Patronage and feast day
Dunstan became patron saint of English goldsmiths and silversmiths because he worked as a silversmith making church plate. The Eastern Orthodox Church and the Roman Catholic Church mark his feast day on 19 May. Dunstan is also honoured in the Church of England and in the Episcopal Church on 19 May.
In 2023, a pastoral area of the Roman Catholic Diocese of Clifton was named in honour of Dunstan.
In literature and folklore
English literature contains many references to him: for example, in A Christmas Carol by Charles Dickens, and in this folk rhyme:
St Dunstan, as the story goes,
Once pull'd the devil by the nose
With red-hot tongs, which made him roar,
That he was heard three miles or more.
This folk story is already shown in an initial in the Life of Dunstan in the Canterbury Passionale, from the second quarter of the 12th century (British Library, Harley MS 315, f. 15v.).
Daniel Anlezark has tentatively suggested that Dunstan may be the medieval author of the poem Solomon and Saturn, citing the style, word choice, and Hiberno-Latin used in the texts. However, Clive Tolley examines this claim from a linguistic point-of-view and disagrees with Anlezark's claim.
Another story relates how Dunstan nailed a horseshoe to the Devil's foot when he was asked to re-shoe the Devil's cloven hoof. This caused the Devil great pain, and Dunstan only agreed to remove the shoe and release the Devil after he promised never to enter a place where a horseshoe is over the door. This is claimed as the origin of the lucky horseshoe.
A further legend relating to Dunstan and the Devil seeks to explain the phenomena of Franklin nights, late frosts which occur around his Feast Day. The story goes that Dunstan was a great brewer and negotiated an agreement whereby the Devil could blast the blossom of local apple trees with frost, damaging the cider crop so that Dunstan's own beer would sell more readily.
An East London saint
As Bishop of London, Dunstan was also Lord of the Manor of Stepney, and may, like subsequent bishops, have lived there. Dunstan is recorded as having founded (or rebuilt) Stepney's church, in 952 AD. This church was dedicated to All Saints, but was rededicated to Dunstan after his canonisation in 1029, making Dunstan the patron saint of Stepney.
References
Notes
Citations
Sources
Further reading
Primary sources
'Author B', Vita S. Dunstani, ed. W. Stubbs, Memorials of St Dunstan, Archbishop of Canterbury. Rolls Series. London, 1874. 3–52. Portions of the text are translated by Dorothy Whitelock in English Historical Documents c. 500–1042. 2nd ed. London, 1979. These have been superseded by the new edition and translation by Michael Lapidge and Michael Winterbottom, The Early Lives of St Dunstan, Oxford University Press, 2012.
Adelard of Ghent, Epistola Adelardi ad Elfegum Archiepiscopum de Vita Sancti Dunstani, Adelard's letter to Archbishop Ælfheah of Canterbury (1005–1012) on the Life of St Dunstan, ed. W. Stubbs, Memorials of St Dunstan, Archbishop of Canterbury. Rolls Series 63. London, 1874. 53–68. Also in the new edition and translation by Michael Lapidge and Michael Winterbottom, The Early Lives of St Dunstan, Oxford University Press, 2012.
Wulfstan of Winchester, The Life of St Æthelwold, ed. and tr. M. Lapidge and M. Winterbottom, Wulfstan of Winchester. The Life of St Æthelwold. Oxford Medieval Texts. Oxford, 1991.
Reliquiae Dunstanianae, ed. W. Stubbs, Memorials of St Dunstan, Archbishop of Canterbury. Rolls Series. London, 1874. 354–439.
Fragmenta ritualia de Dunstano, ed. W. Stubbs, Memorials of St Dunstan, Archbishop of Canterbury. Rolls Series. London, 1874. 440–57.
Osbern of Canterbury, Vita sancti Dunstani and Liber Miraculorum Sancti Dunstani, ed. W. Stubbs, Memorials of St Dunstan, Archbishop of Canterbury. Rolls Series. London, 1874. 69–161.
Eadmer, Vita S. Dunstani and Miracula S. Dunstani, ed. and tr. Bernard J. Muir and Andrew J. Turner, Eadmer of Canterbury. Lives and Miracles of Saints Oda, Dunstan, and Oswald. OMT. Oxford, 2006. 41–159 and 160–212; ed. W. Stubbs, Memorials of St Dunstan, archbishop of Canterbury. Rolls Series 63. London, 1874. 162–249, 412–25.
An Old English Account of the King Edgar's Establishment of the Monasteries, tr. D. Whitelock, English Historical Documents I. Oxford University Press, 1979.
Secondary sources
Dales, Douglas, Dunstan: Saint and Statesman, 3rd ed., James Clark & Co, 2023
Duckett, Eleanor. Saint Dunstan of Canterbury (1955).
Dunstan, St. Encyclopedia of World Biography, 2nd ed. 17 vols. Gale Research, 1998.
Knowles, David. The Monastic Orders in England (1940; 2d ed. 1963).
Ramsay, Nigel St Dunstan: his Life, Times, and Cult, Woodbridge, Suffolk, UK; Rochester, NY: Boydell Press, 1992.
Sayles, G. O., The Medieval Foundations of England (1948; 2d ed. 1950).
William of Malmesbury, Vita sancti Dunstani, ed. and tr. Bernard J. Muir and Andrew J. Turner, William of Malmesbury. Lives of SS. Wulfstan, Dunstan, Patrick, Benignus and Indract. Oxford Medieval Texts. Oxford, 2002; ed. W. Stubbs, Memorials of St Dunstan, Archbishop of Canterbury. Rolls Series. London, 1874. 250–324.
John Capgrave, Vita sancti Dunstani, ed. W. Stubbs, Memorials of St Dunstan, Archbishop of Canterbury. Rolls Series. London, 1874. 325–53.
External links
The True Legend of St. Dunstan and the Devil by Edward G. Flight, illustrated by George Cruikshank, published in 1871, and available from Project Gutenberg
Dunstan at the British Library, BL medieval manuscripts blogpost, May 2016
900s births
988 deaths
10th-century English archbishops
10th-century artists
10th-century Christian saints
10th-century English bishops
Abbots of Glastonbury
Angelic visionaries
Anglican saints
Anglo-Saxon artists
Anglo-Saxon Benedictines
Anglo-Saxon saints
Archbishops of Canterbury
Bishops of London
Bishops of Worcester
English blacksmiths
English folklore
Manuscript illuminators
Medieval European scribes
English scribes
People from Mendip District
Year of birth uncertain
English silversmiths
10th-century Christian abbots | Dunstan | Physics | 5,330 |
29,213,054 | https://en.wikipedia.org/wiki/Glossary%20of%20spider%20terms | This glossary describes the terms used in formal descriptions of spiders; where applicable these terms are used in describing other arachnids.
Links within the glossary are shown .
Terms
A
Abdomen or opisthosoma: One of the two main body parts (tagmata), located towards the posterior end; see also Abdomen § Other animals
Accessory claw: Modified at the tip of the in web-building spiders; used with to grip strands of the web
Anal tubercle: A small protuberance (tubercule) above the through which the anus opens
Apodeme: see
Apophysis (plural apophyses): An outgrowth or process changing the general shape of a body part, particularly the appendages; often used in describing the male : see
Atrium (plural atria): An internal chamber at the entrance to the in female haplogyne spiders
B
Bidentate: Having two
Book lungs: Respiratory organs on the ventral side (underside) of the , in front of the , opening through narrow slits; see also Book lungs
Branchial operculum: see
Bulbus: see
C
Calamistrum (plural calamistra): Modified setae (bristles) on the of the fourth leg of spiders with a , arranged in one or more rows or in an oval shape, used to comb silk produced by the cribellum; see also Calamistrum
Caput (plural capita): see
Carapace: A hardened plate (sclerite) covering the upper (dorsal) portion of the ; see also Carapace
Carpoblem: The principal on the male ; also just called the tibial apophysis
Cephalic region or caput: The front part of the , separated from the thoracic region by the
Cephalothorax or prosoma: One of the two main body parts (tagmata), located towards the anterior end, composed of the head ( or caput) and the thorax (thoracic region), the two regions being separated by the ; covered by the and bearing the , legs, and mouthparts
Cervical groove: A shallow U-shaped groove, separating the and thoracic regions of the
Chelate: A description of a where the closes against a tooth-like process
Chelicera (plural chelicerae): One of two appendages at the front of the , made up of basal portion, the , and the ; sometimes called the jaw; see also Chelicerae
Cheliceral furrow: A shallow groove on the basal portion of a accommodating the , usually having on its margins
Cheliceral tooth: A tooth-like extension on the margin of the
Chilum: A small hardened plate (sclerite) at the base of the , under the
Claw: see
Claw tuft: A dense group of hairs or bristles (setae) underneath the paired , usually well developed in hunting spiders
Clypeus: The area of the between the anterior (frontmost) and the anterior edge of the carapace
Colulus: A short protuberance in the middle of the underside of the in front of the , considered to be a modification of the
Conductor: see
Copulatory duct: An internal tube (duct) from the through which sperm enters the female; separate from the duct through which fertilized eggs pass in entelegyne spiders
Copulatory opening: An opening in the ventral of female spiders; in entelegyne spiders, a double opening in the through which the is inserted; in haplogyne spiders, a single opening through which male is inserted
Coxa: see
Crenulate: Having longitudinal ridges
Cribellum: A sieve-like plate in front of the , used in conjunction with the ; spiders with a cribellum are called cribellate, those without ecribellate; see also Cribellum
Cuspule: A small spiny outgrowth ("wart") on the and of Mygalomorphae
Cymbium (plural cymbia): The end part of the of the in a mature male, usually hollowed out and bearing the
D
Dionychous: With two on the of each leg; a feature of spiders in the clade Dionycha
Dorsal groove: see
Dorsum: The upper (dorsal) portion or surface of the body or ; the adjective dorsal may be applied to the upper portion or surface of any part of the body; see
E
Ecribellate: see
Embolus: see
Endite: see
Endosternite: An internal hardened plate (sclerite)
Entelegyne: A spider whose female has an and separate ducts leading to for sperm storage and to the uterus for fertilization, creating a "flow-through" system; see ; see also Entelegynae
Epigastric furrow or epigastric fold: A transverse slit towards the front (anterior) of underside of the ; the front pair of open at the edge of this furrow as do the genital openings ()
Epigyne or epigynum (plural epigynes): A hardened plate on the underside of the female in which the are located; only fully developed in mature females of spiders; see also Epigyne
Eyes: The basic number of eyes is eight, typically arranged in two rows (e.g. as in Gnaphosidae); the front row are the anterior eyes, the row behind the posterior eyes; the four eyes to the edges are the lateral eyes, the four eyes in the centre the median eyes; the anterior median eyes are called the main eyes or direct eyes, while the other eyes are called the secondary eyes or indirect eyes; the number of eyes, their sizes and arrangement varies widely and is characteristic of spider families; see ,
F
Fang: The final hinged part of the , normally folded down into a groove in the basal part of the chelicera; venom is injected via an opening near the tip of the fang
Femur: see
Fertilization duct: A duct in female spiders leading from the to the uterus
Folium: A broad leaf-like marking along the medial line of the top of the
Fossa (plural fossae): A pit or depression, typically in the
Fovea (also called thoracic furrow or dorsal groove): A depression or pit in the centre of the of a spider marking an inward projection of the exoskeleton to which stomach muscles are attached
G
Genital opening: see
Gnathocoxa: see
Gonopore: The genital opening; located in the epigastric furrow; the opening of the duct from the uterus in females and from the testes in males; see also Gonopore
Gravid: A fertilised female with an enlarged abdomen section right before egg laying has begun.
H
Haematodocha (also spelled hematodocha): see
Haplogyne: A spider whose female lacks an and in which the same ducts are used to transport sperm to the uterus and to the ; see ; see also Haplogynae
Heart mark: A narrow marking along the top of the roughly corresponding to the location of the heart
L
Labio-sternum mound: A mound separating the from the , found in some tarantulas, where it can be a diagnostic feature
Labium (plural labia): A hardened plate (sclerite) between the at the front of the ; see also Arthropod mouthparts: Labium
Labrum: see
Lateral (applied to appendages): Viewed from above or below, the sides of the leg or , i.e. the surfaces parallel to the line of sight; see ,
Laterigrade: With legs directed to the side, hence appearing like and moving like a crab; see
Leg formula: The legs are numbered from the front from I to IV; the relative length of the legs can be represented by four numbers from the longest to the shortest; e.g. 1423 = first leg (leg I) is longest and third leg (leg III) is shortest
Leg parts or segments: see
M
Main eye: One of the two anterior median eyes (AME) that have the light-detecting units (rhabdomeres) pointing towards the source; particularly enlarged in the families Salticidae and Thomisidae; see ,
Mastidion (plural mastidia): A projection or bump on the chelicerae (not to be confused with )
Maxilla (plural maxillae; also called endite or gnathocoxa): Modified of the , used in feeding; not the structure called by this name in other arthropods, for which see Maxilla (arthropod mouthpart)
Metatarsus: see
O
Ocular area or ocular quadrangle: The area of the which includes the .
Operculum or branchial operculum (plural opercula): One of the plates on the surface of the , just in front of the , covering the , often pale, yellow or orange in colour; two pairs in Mygalomorphae, one pair in other spiders
Opisthosoma: see
P
Palp: see
Palpal bulb (also called bulbus, palpal organ, genital bulb): The copulatory organ of the male spider, carried on the modified last segment of the , used to transfer sperm to the female; see also Palpal bulb
Conductor: A part of the palpal bulb that accompanies and supports the embolus
Embolus: The final part of the palpal bulb containing the end of the sperm duct, usually thin, sharp-tipped and strongly hardened (sclerotized)
Haematodocha (plural haematodochae): A membranous, inflatable part of the palpal bulb
Median apophysis: A projection (apophysis) of the palpal bulb, below the conductor
Subtegulum: A hardened part of the palpal bulb nearer its base than the tegulum
Tegulum: The main hardened part of the palpal bulb
Paracymbium: An outgrowth of the on the male
Patella: see
Paturon: The basal segment of a to which the connects
Pedicel or petiolus: The narrow connection between the and
Pedipalp (plural pedipalps or pedipalpi; also called just palp): The second appendage of the in front of the first leg; bears the in male spiders; see , see also Pedipalp
Plumose: Used to describe hairs () having outgrowths or appendages on two sides, giving a feather-like appearance; the appendages vary in number, size and arrangement
Pluridentate: Having multiple
Postembryo (also called larva): The stage of development between hatching from the egg and first molting
Preening brush: a dense cluster of near the tip of the posterior ; called a preening comb when present as a transverse row of setae.
Procurved: Used to describe a structure which is curved in such a way that the outer edges are in front of the central part; opposite
Prolateral: Viewed from above or below, the side of a leg or nearest the mouth, i.e. the side facing forward; opposite (includes diagram)
Promarginal: The side of the facing forward; particularly used for describing ; opposite
Prosoma: see
R
Rastellum (plural rastella): An often rake-like structure at end of the in mygalomorph spiders; used in burrowing
Rebordered: Having a thickened edge (i.e. border) (more rarely seen as reborded, from the French , e.g. in Levy (1984)); particularly used of the
Receptaculum (plural receptacula): see
Recurved: Used to describe a structure which is curved in such a way that the outer edges are behind the central part; opposite
Retrolateral: Viewed from above or below, the side of a leg or furthest from the mouth, i.e. the side facing backwards; opposite
Retrolateral tibial apophysis: A backward-facing projection on the tibia of the male ; distinguishing feature of the RTA clade
Retromarginal: The side of the facing backward (towards the posterior end of the spider); particularly used for describing ; opposite
Rostrum (also called labrum): A component (the "upper lip") of the mouthparts, concealed by the ; see also Arthropod mouthparts: Labrum
S
Scape: An elongated process or appendage of some
Sclerite: A single hardened (sclerotized) part of the external covering (tegument, exoskeleton)
Scopula (plural scopulae): A brush of hairs (setae); called a when on the end of the foot (tarsus), where it improves adhesion
Scutum (plural scuta): A hardened (sclerotized) plate on the of some spiders
Secondary eye: An eye belonging to the three pairs – anterior lateral eyes (ALE), posterior median eyes (PME) and posterior lateral eyes (PLE) – that are primarily movement detectors and have the light-detecting units (rhabdomeres) pointing away from the source; see ,
Segments or articles of the legs and :
Coxa (plural coxae): First leg segment, between body and trochanter; the coxa of the is heavily modified to form the or endite
Trochanter: Second leg segment, between coxa and femur
Femur (plural femora): Third leg segment, between trochanter and patella
Patella (plural patellae): Fourth leg segment, between femur and tibia
Tibia (plural tibiae): Fifth leg segment, between patella and metatarsus
Metatarsus (plural metatarsi; also called basitarsus): Sixth leg segment, between tibia and tarsus; absent in the
Tarsus (plural tarsi; also called telotarsus): Seventh (last) leg segment, after the metatarsus
Serrula: A row of tiny teeth along the edge of the
Seta (plural setae): A bristle; spiders have a variety of hair-like structures of increasing size that are referred to as hairs, bristles (setae) or
Sigillum (plural sigilla): A circular indentation on the outside of the spider, showing where an internal muscle is attached; particularly on the in some Mygalomorphae and on the in some Araneomorphae
Sperm duct: A duct in the male used to store sperm
Spermatheca (plural spermathecae; also called receptulacum, receptulacum seminis): A structure in the of female spiders used to store sperm after insemination and before fertilization; see also Spermatheca
Spigot: A small pointed or cylindrical structure at the tip of a from which silk emerges
Spine: A pointed, rigid structure on body and legs, usually with a basal joint; spiders have a variety of hair-like structures of increasing size that are referred to as hairs, bristles (setae) or spines
Spinneret: An appendage borne on the , typically one of six arranged in three pairs: anterior (anterior median, AMS), median (posterior median, PMS) and posterior (posterior lateral, PLS); silk emerges from small on the spinnerets; see also Spinneret
Sternum: The lower (ventral) portion of the
Stridulating organ: A series of thin ridges on a hardened part of the body; rubbing this with a matching series of short, stiff bristles (setae) elsewhere on the body creates a sound
Subadult: A spider in the last stage of development (penultimate instar) before becoming a sexually mature adult
Subtegulum: see
T
Tapetum (plural tapeta): A light-reflecting layer in a making the eye appear pale
Tarsal claw (claw): One of a set of claws at the tip of the ; there may be a single pair, often concealed in a , or an additional third central claw, much smaller than the other two
Tarsal organ: a small pit, usually spherical and on the surface of each , believed to respond to humidity
Tarsus: see
Teeth: Pointed growths or bumps along the margins of the
Tegulum: see
Thoracic furrow: see
Tibia: see
Trachea (plural tracheae): A thin hardened internal tube, part of the respiratory system in many araneomorph spiders; opens on the underside of the via a tracheal spiracle; see Trachea § Invertebrates
Trichobothrium (plural trichobothria): A slender hair-like structure of variable length on the legs and , arising from a special socket; used to detect air movements, including sounds; see ,
Trochanter: see
U
Unidentate: Having a single tooth
V
Venter (or ventrum): The lower (ventral) portion or surface of the body or ; the adjective ventral may be applied to the lower portion or surface of any part of the body; see
Vulva: The internal copulatory organs of a female spider, including the , , and
Abbreviations
Some abbreviations commonly found in descriptions of spider anatomy include:
ALE: anterior lateral eyes →
ALS: anterior lateral spinnerets →
AME: anterior median eyes →
DTA: dorsal tegular apophysis, on the back of the
DTiA: dorsal tibial apophysis, on the back of a
ITC: inferior tarsal claw →
LTA: lateral tegular apophysis, apophysis on the side of the
MOQ: median ocular quadrangle, the quadrangle formed by the four median eyes, →
PLE: posterior lateral eyes →
PLS: posterior lateral spinnerets →
PME: posterior median eyes →
PMS: posterior median spinnerets →
RCF: retrolateral cymbial fold, fold on the surface of the
RTA: retrolateral tibial apophysis, on the surface of a
STC: superior tarsal claw →
VTA: ventral tegular apophysis, on the underside of the
VTiA: ventral tibial apophysis, on the lower surface of a
See also
Spider anatomy
Glossary of entomology terms
Anatomical terms of location
References
Bibliography
Spider terms
Wikipedia glossaries using unordered lists | Glossary of spider terms | Biology | 3,870 |
8,813,868 | https://en.wikipedia.org/wiki/Frosty%20Leo%20Nebula | The Frosty Leo Nebula is a protoplanetary nebula (PPN) located roughly at 3000 light-years away from Earth in the direction of the constellation Leo. It is a spectral bipolar nebula. Its central star is of optical spectral type K7II, by itself called Frosty Leo. It is unusual in that it has an extremely deep absorption feature at 3.1 μm and is unusually located at more than 900 pc above the plane of our galaxy. Further, as of 1990, it has the only known PPN circumstellar outflow in which crystalline ice dominates the long-wavelength emission spectrum and the only known PPN with point-reflection-symmetric deviations from axial symmetry.
Characteristics
The Frosty Leo Nebula has two lobes that are separated by 2 between which is an almost edge-on dust ring. It also has two relatively faint but prominent compact nebulosities, or ansae, separated by ~23 along the polar axis of the PPN. The PPN as a whole has an hourglass like shape. It has an inclination angle of 15° relative to the plane of the sky. Its molecular envelope is expanding at a rate of ~25 km/s.
Observation history
This PPN was first noticed in the IRAS survey due to its exceptionally cold IRAS color temperatures. It also has a uniquely sharp maximum at 60-μM.
Point symmetry
It is the first bipolar PPN known to have point reflection symmetry (all others being axially symmetric). Point symmetry is a fairly common trait of planetary nebulae as found in NGC 2022, NGC 2371-2, NGC 6309, Cat's Eye Nebula, NGC 6563, Dumbbell Nebula, Saturn Nebula, A24, and Hb5. postulate that point symmetry is either due to the bipolar outflow being directed by a precessing disc or a precessing common envelope binary.
Naming
dubbed IRAS 09371+1212 as the "Frosty Leo Nebula" because of their interpretation of the object's extremely unusual far infrared spectrum that water is largely depleted in its gaseous state by ice condensation into grains and for its location in the Leo constellation. Their interpretation was subsequently verified in 1988 by three independent papers. further observed in the band between 35 and 65 μM that very cold (<50 K) silicate dust grains, abundantly coated with crystalline ice, are responsible for the 60-μM excess.
Notes
References
External links
Image of Frosty Leo Nebula.
Protoplanetary nebulae
Leo (constellation) | Frosty Leo Nebula | Astronomy | 521 |
21,245,910 | https://en.wikipedia.org/wiki/Teleforce | Teleforce is a proposed defensive weapon by Nikola Tesla that accelerated pellets or slugs of material to a high velocity inside a vacuum chamber via electrostatic repulsion and then fired them out of aimed nozzles at intended targets. Tesla claimed to have conceived of it after studying the Van de Graaff generator. Tesla described the weapon as being able to be used against ground-based infantry or for anti-aircraft purposes.
Description
Tesla described Teleforce'''s operation in 1934, specifying its superiority to the death rays believed to exist at the time: My apparatus projects particles which may be relatively large or of microscopic dimensions, enabling us to convey to a small area at a great distance trillions of times more energy than is possible with rays of any kind. Many thousands of horsepower can thus be transmitted by a stream thinner than a hair, so that nothing can resist. The nozzle would send concentrated beams of particles through the free air, of such tremendous energy that they will bring down a fleet of 10,000 enemy airplanes at a distance of 200 miles from a defending nation's border and will cause armies to drop dead in their tracks.
In a letter that was written to J. P. Morgan, Jr. on November 29, 1934, Tesla described the weapon:
I have made recent discoveries of inestimable value... The flying machine has completely demoralized the world, so much that in some cities, as London and Paris, people are in mortal fear from aerial bombing. The new means I have perfected afford absolute protection against this and other forms of attack. ... These new discoveries, which I have carried out experimentally on a limited scale, have created a profound impression. One of the most pressing problems seems to be the protection of London and I am writing to some influential friends in England hoping that my plan will be adopted without delay. The Russians are very anxious to render their borders safe against Japanese invasion and I have made them a proposal which is being seriously considered.
In 1937, Tesla wrote a treatise, "The Art of Projecting Concentrated Non-dispersive Energy through the Natural Media", concerning charged particle beam weapons. Tesla published the document in an attempt to expound on the technical description of a 'superweapon" that would put an end to all war." This treatise is currently in the Nikola Tesla Museum archive in Belgrade. It describes an open-ended vacuum tube with a gas jet seal that allows particles to exit, a method of charging particles to millions of volts, and a method of creating and directing non-dispersive particle streams (through electrostatic repulsion).
"Death ray" misnomer
Teleforce was mentioned publicly in the New York Sun and The New York Times'' on July 11, 1934. The press called it a "peace ray" or death ray. The idea of a "death ray" was a misunderstanding in regard to Tesla's term when he referred to his invention as a "death beam" so Tesla went on to explain that "this invention of mine does not contemplate the use of any so-called 'death rays.' Rays are not applicable because they cannot be produced in requisite quantities and diminish rapidly in intensity with distance. All the energy of New York City (approximately two million horsepower) transformed into rays and projected twenty miles, could not kill a human being, because, according to a well known law of physics, it would disperse to such an extent as to be ineffectual. My apparatus projects particles ..."
What set Tesla's proposal apart from the usual run of fantasy "death rays" was a unique vacuum chamber with one end open to the atmosphere. Tesla devised a unique vacuum seal by directing a high-velocity air stream at the tip of his gun to maintain "high vacua". The necessary pumping action would be accomplished with a large Tesla turbine.
Components of Teleforce
In total, the components and methods included:
An apparatus for producing manifestations of energy in free air instead of in a high vacuum as in the past.
A mechanism for generating tremendous electrical force.
A means of intensifying and amplifying the force developed by the second mechanism.
A new method for producing a tremendous electrical repelling force. This would be the projector, or gun, of the invention.
It has been said that the charged particles would self-focus via "gas focusing,". In 1940, Tesla estimated that each station would cost no more than $2,000,000 and could have been constructed in a few months.
After Tesla died, in a box purported to contain a part of Tesla's "death ray" apparatus, John G. Trump found a 45-year-old multidecade resistance box.
Attempts at development and marketing
By November 1934, Tesla was attempting (unsuccessfully) to obtain funding from J. P. Morgan's son, Jack Morgan. The idea of Tesla possibly having a new type of weapon and, further, his offer to give it to the League of Nations as a way to prevent future war were seen together as an alarming security threat by one US diplomat – a view not shared by his government. In 1935, the Soviet Union, through the US Amtorg Trading Corporation, an alleged Soviet-arms front in New York City, paid Tesla $25,000 for detailed plans, specifications, and complete information on the method and apparatus, but it is unclear whether a physical device was ever produced. Tesla also attempted to get funding for his device in 1937, sending a paper ("New Art of Projecting Concentrated Non-Dispersive Energy Through Natural Media") outlining his plans to the governments of the United States, the United Kingdom, France, Canada, and Yugoslavia. The United Kingdom considered Tesla's offer to sell the device to them for $30 million, maybe with the idea that even hinting they had a super weapon would be a deterrent to Adolf Hitler, but by 1938 they had dropped all interest.
During this period, Tesla claimed that efforts had been made to steal the invention, saying that his room had been entered and that his papers had been scrutinized, but that the thieves or spies had left empty-handed. He said that there was no danger that his invention could be stolen, for he had at no time committed any part of it to paper; the blueprint for the Teleforce weapon was all in his mind.
At his birthday press conference in 1937, Tesla was asked about his weapon, and he made the claim, "But it is not an experiment... I have built, demonstrated and used it. Only a little time will pass before I can give it to the world." At the 1940 birthday press conference, 84-year-old Tesla offered to develop his weapon for the US, but there was no interest in his offer.
See also
Coilgun
Railgun
References
External links
Tesla Tries To Prevent World War II by John J. O'Neill
The New Art of Projecting Concentrated Non-dispersive Energy Through Natural Media by Nikola Tesla
Inventions by Nikola Tesla
Lost inventions
Systems engineering | Teleforce | Engineering | 1,455 |
72,415,186 | https://en.wikipedia.org/wiki/Legendrea | Legendrea is a genus of extremely rare ciliates first described by French biologist Emmanuel Fauré-Fremiet in 1908, rediscovered and re-examined in 2022.
Classification
The genus has 5 species including the type species, Legendrea loyezae, described in 1908. Other genera (e.g. Lacerus and Thysanomorpha) were only distinguished from Legendrea by their physical appearance, not affinities. These genera were misidentifications and were synonymised with Legendrea along with their respective species. First true taxonomic assignment of the cilliate was made in December 2022. The current 5 species are:
Legendrea bellerophon [=Thysanomorpha bellerophon ]
Legendrea crassa [=Penardiella crassa ]
Legendrea interrupta
Legendrea loyezae
Legendrea pespelicani [=Lacerus pespelicani ]
Taxonomic affinities
The genus (and species) are distinguishable from one another by the length of their finger-like tentacles. These tentacles are located at the rear end of the cell. Varied descriptions of these tentacles have been attributed to their different morphologies when swimming versus at rest, such as in the case of L. loyezae. Phylogenetic analysis of the 18S rRNA gene within L. loyezae placed the genus within the family Spathidiidae taxonomically ranked under the order of Haptorida. A shorter gene of 18S rRNA was used to classify the species and so its affinity should be carefully interpreted with there being the likelihood of it changing to a new affinity. The sequence used to determine the identity of L. loyezae implies that it forms a sister group with the sequences from the re-identified Epispathidium papilliferum as well as an undescribed species of the same genus. The Epispathidium possessed protruding papillae that are analogous to those found on L. loyezae, although the papillae on Epispathidium were only present on its oral region.
Genus divisions
Although A. Jankowski did not directly observe any members of Legendrea, Jankowski published a revision of the genus that divided Legendrea into two genera based on morphological differences: Lacerus and Thysanomorpha. Legendrea bellerophon was reclassified to the genus Thysanomorpha and was renamed Thysanomorpha bellerophon, re-described as having a serrated body edge/surface with an uneven series of outgrowths with trichomes. These names of the species and genera were in use by subsequent publications, but were challenged by Weiss et al. in 2022 as misidentifications of Legendrea species.
References
Litostomatea
Ciliate genera
Microscopic eukaryotes
Taxa described in 1908 | Legendrea | Biology | 584 |
65,433,466 | https://en.wikipedia.org/wiki/Maternal%20recognition%20of%20pregnancy | Maternal recognition of pregnancy is a crucial aspect of carrying a pregnancy to full term. Without maternal recognition to maintain pregnancy, the initial messengers which stop luteolysis and promote foetal implantation, growth and uterine development finish with nothing to replace them and the pregnancy is lost.
Pregnancy maintenance relies on the continued production of progesterone which is initially produced by the corpus luteum (CL). A hormone secreting structure that develops on the ovary after ovulation. Maternal recognition of pregnancy differs between species, however they all include a signal to prevent luteolysis, which then prevents the resumption of menstrual or oestrous cycles.
Luteolysis is the regression of the corpus luteum. The process is identified by the decline of progesterone and it signifies the absence of pregnancy following ovulation. In the non pregnant uterus, the decline of progesterone allows the return of oestrogen, resulting in the upregulation of oxytocin receptors and consequently pulsatile release of PGF2α. In turn, luteolysis is induced. This regression allows the continuation of the menstrual cycle.
However, if pregnancy is established, luteolysis is evaded via maternal recognition of pregnancy because high levels of progesterone are maintained by the CL and the placental hormone hCG further maintains the CL.
Mechanisms of recognition
Human
Progesterone released from the corpus luteum is promoted by human chorionic gonadotrophin (hCG) produced by the cells of the trophoblast, the outer layer of cells of the early embryo.
Sheep and cow
In most ruminant species, interferon tau has been identified as the signal for maternal recognition of pregnancy . Interferon tau is therefore also referred to as an anti luteolytic factor, essential for the maintenance of the corpus luteum.
Interferon tau is secreted by the trophectoderm of the blastocyst from around day 10 in ovine species and from day 15 in bovine species. Interferon tau acts on the endometrial cells of the maternal uterus to prevent the production of the luteolytic factor, PGF2ɑ. The inhibition of PGF2ɑ production is the result of a change in gene expression. Interferon tau inhibits the transcription of the oxytocin receptor gene in both sheep and cows, and also the oestrogen receptor ɑ gene in sheep. The absence of these receptors in the cells of the endometrium prevents the pulsatile release of PGF2ɑ.
References
Reproduction in animals
Reproduction in mammals
Hormones | Maternal recognition of pregnancy | Biology | 558 |
47,414,167 | https://en.wikipedia.org/wiki/Desi%20daru | Desi daru (), also known as country liquor or Indian-made Indian liquor (IMIL), is a local category of liquor produced on the Indian subcontinent, as opposed to Indian-made foreign liquor. Due to cheap prices, country liquor is the most popular alcoholic beverage among the impoverished people. It is fermented and distilled from molasses, a by-product of sugarcane. Desi liquor is a broad term and it can include both legally and illegally made local alcohol. The term desi daru usually refers to legal alcohol while other types of country liquor (arrack and palm toddy) may be categorised as moonshine alcohol.
Etymology
The term desi, from Hindi language term desh (country or region), which is generally an endonym for the compatriot or local is often applied to food or drink that is considered traditional or native. Dārū (Hindi दारू and Urdu دارو) is a Persian-derived term used for any alcoholic beverage in India. Śarāb (Hindi शराब and Urdu شراب) is another Persian-derived equivalent and is used in some areas with less frequency.
Industry
An article in the medical journal The Lancet estimated that nearly two-thirds of the alcohol consumed in India is country liquor. Globus spirits mentioned that India's country liquor market is about 242 million cases (over 30% of the beverage industry in India) with a growth rate of about 7% per annum. No data regarding Pakistan is available as drinking alcohol is officially prohibited for Muslims in Pakistan, although locally made liquor is sold on the black market.
Government regulation provide for a separate licensing for production, distribution and retailing of country liquor (IMIL) as opposed to Indian-made foreign liquor.
Social issues
Country liquor, being the cheapest alcohol in India, is the mainstay alcoholic beverage for the rural population and urban poor. In rural areas, illicit country liquor has been blamed for domestic violence and poverty in the family. There have been several protests against country liquor shops/bars in villages.
Adulteration
As country liquor is cheaper than other spirits, there have been reports of mixing country liquor with Scotch/English whisky in many bars in India.
If care is not taken in the distillation process and the proper equipment is not used, harmful impurities such as fusel alcohols, lead from plumbing solder, and methanol can be concentrated to toxic levels. Several deaths have been reported in India and Pakistan due to consumption of non-factory made toxic liquor.
In popular culture
There are several references of desi daru in Bollywood films, songs.
2012 film Cocktail has song named Daru Desi sung by Benny Dayal and Shalmali Kholgade.
2011 film F.A.L.T.U has party song named Char Baj Gaye (Party Abhi Baaki Hai) has reference of desi daru.
Scenes in 2011 film Rockstar shows lead actor Ranbir Kapoor and lead actress Nargis Fakhri drinking desi daru.
2014 film Main Aur Mr. Riight has song named Desi Daru sung by Jasbir Jassi.
See also
Alcoholic Indian beverages
Beer in India
Indian-made foreign liquor
Indian whisky
Lion beer, Asia's first beer brand
Solan No. 1, India's first malt whisky
Old Monk, iconic Indian rum
Sura
Other India alcohol related
Alcohol laws of India
Alcohol prohibition in India
Dry Days in India
References
External links
Photo of Desi daru by ''Firstpost
Indian alcoholic drinks
Indian distilled drinks
Desi cuisine
Desi culture
Traditional Indian alcoholic beverages
Adulteration | Desi daru | Chemistry | 751 |
78,769,427 | https://en.wikipedia.org/wiki/Eitaa%20Messenger | Eitaa Messenger () is an Iranian instant messaging (IM), VoIP service, and social media platform developed by the Idea of Today's Civilization Supporters Company. It is one of the most widely used messaging platforms in Iran, with more than 40 million users. Eitaa enables users to send text and voice messages, share images and videos, make voice and video calls, share files and locations, pay bills, and access services.
Eitaa is available on Android, iOS, macOS, Windows, Linux, and the web. Registration requires a mobile telephone number.
History
Eitaa was introduced as part of Iran's growing digital ecosystem, as a local alternative to international messaging platforms. Over the years, it has become a popular messaging app for millions of users in Iran, meeting the communication, business, and social networking needs of both domestic and international users. It was removed by Google Play and Apple store in 2022 along with many other Iranian platforms.
Features
Eitaa has a range of features designed for communication and user experience. These include text and voice messaging, multimedia sharing, voice and video calls, and file sharing. The platform also provides payment services for tasks such as paying bills, making purchases, and conducting transactions securely. Users can share their real-time location and access a variety of services through bots, including customer support and bill payments.
Message Exchange Bus (MXB)
Eitaa is connected to the Message Exchange Bus (MXB), which is a technology that connects major Iranian messaging platforms like Bale, Eitaa, Soroush, Rubika, Gap and iGap and enables users to send messages and files and more between these apps without needing a separate account for each one, offering communication regardless of the platform used. This system is instrumental in creating a unified messaging ecosystem in Iran and is created for the first time in Iran.
Social networking
Eitaa has some social networking features, including the ability for users to follow public accounts, participate in channels, share updates, photos, and videos. While the platform is widely adopted for social interaction, its features aim to meet a broad range of user needs, contributing to its growing use as a social platform.
Services
Banking Services
Eitaa offers banking features, including bill payments, account recharges, and other financial tasks. These services are integrated into the app, allowing users to perform various financial transactions.
Bots and AI
Eitaa includes AI-powered bots that assist with tasks such as subscription management, business services, and customer support. These bots are intended to automate certain processes within the app.
Removal from Amarican app stores
Eitaa was removed from both the Google Play Store and the Apple App Store, along with several other Iranian apps. This removal came as part of a broader action taken by these platforms to restrict access to apps from Iran. Despite this, Eitaa continues to be available through other app stores and to direct download, maintaining its user base.
See also
Bale
Rubika
Messaging apps
References
External links
Official website
Android (operating system) software
Instant messaging clients
Iranian social networking websites | Eitaa Messenger | Technology | 634 |
4,191,602 | https://en.wikipedia.org/wiki/PNP%20agar | PNP Agar is an agar medium used in microbiology to identify Staphylococcus species that have phosphatase activity. The medium changes color when p-nitrophenylphosphate disodium (PNP) is dephosphorylated.
PNP agar is composed of Mueller–Hinton agar buffered to pH 5.6 to 5.8, with the addition of 0.495 mg/mL PNP.
References
Microbiological media
Cell culture media | PNP agar | Biology | 107 |
45,662,917 | https://en.wikipedia.org/wiki/Penicillium%20heteromorphum | Penicillium heteromorphum is a species of the genus of Penicillium.
References
heteromorphum
Fungi described in 1988
Fungus species | Penicillium heteromorphum | Biology | 35 |
3,340,851 | https://en.wikipedia.org/wiki/Migrating%20motor%20complex | Migrating motor complex, also known as migrating myoelectric complex, migratory motor complex, migratory myoelectric complex and MMC, is a cyclic, recurring motility pattern that occurs in the stomach and small bowel during fasting; it is interrupted by feeding. A pattern of electrical activity is also observed in the gastrointestinal tract in a regular cycle during this interdigestive period.
MMC was discovered and characterized in fasting dogs in 1969 by Dr. Joseph H. Szurszewski at the Mayo Clinic. He also showed that this activity stops upon eating a meal, and suggested that it induces a motor activity that acts as an "interdigestive housekeeper" in the small intestine. These motor complexes trigger peristaltic waves, which facilitate transportation of indigestible substances such as bone, fiber, and foreign bodies from the stomach, through the small intestine, past the ileocecal sphincter, and into the colon. MMC activity varies widely across individuals and within an individual when measured on different days. The MMC occurs every 90–230 minutes during the interdigestive phase (i.e., between meals) and is responsible for the rumbling experienced when hungry. It also serves to transport bacteria from the small intestine to the large intestine and to inhibit the migration of colonic bacteria into the terminal ileum; an impairment to the MMC typically results in small intestinal bacterial overgrowth.
Phases
The MMC originates mostly in the stomach—although ~25% will arise from the duodenum or proximal jejunum—and can travel to the distal end of the ileum. They consist of four distinct phases:
Phase I – A prolonged period of quiescence (40–60% of total time);
Phase II – Increased frequency of action potentials and smooth muscle contractility (20–30% of total time);
Phase III – A few minutes of peak electrical and mechanical activity (5–10 minutes);
Phase IV – Declining activity which merges with the next Phase I.
Regulation
Movements of the small bowel are believed to be controlled by the central and enteric nervous systems, intestinal muscles, and numerous peptides and hormones. For example, the MMC is thought to be initiated by motilin, and it does not directly depend on extrinsic nerves. Additionally, gastrin, insulin, cholecystokinin, glucagon, and secretin have been reported to disrupt the MMC.
Eating interrupts the MMC. For example, one study found that a continental breakfast of 450 Kcal causes the MMC to disappear for 213 ± 48 minutes. The number of calories and nature of food determine the length of the disruption with fats causing a longer disruption than carbohydrates which in turn cause a longer disruption than protein.
Most of the cleaning waves in the MMC happen at night while we are asleep. For many people this will be sufficient to help maintain a healthy, balanced environment in the digestive tract. For others, it may be beneficial to space out food intake to allow for a couple cleaning waves to occur between meals throughout the day as well.
Impairment
Autoimmunity following infection by a pathogen producing CdtB, such as C. jejuni, may be the leading cause of MMC impairment. Narcotics are also known to impair the MMC. Stress has been shown to reduce MMC activity as well.
Patients with SIBO and IBS have on average a third as many MMC phase III events with those events being roughly 30% shorter on average.
Therapeutic stimuli
Drugs used to enhance gastrointestinal motility are generally referred to as prokinetics. Serotonin induces phase III of the MMC, and so serotonin receptor agonists are commonly administered as prokinetics. Motilin administration causes phase III contractions, and so motilin agonists are another common prokinetic.
Eradication of bacterial overgrowth has been shown to partially restore MMC activity.
An elemental diet has been hypothesized to partially restore MMC function.
References
External links
Digestive system | Migrating motor complex | Biology | 863 |
49,534,267 | https://en.wikipedia.org/wiki/Smartcat | Smartcat is a cloud-based translation and localization platform that connects businesses, translators, and translation agencies in a single Connected Translation delivery loop. The platform positions itself as an "all-in-one" translation platform, combining CAT, TMS, and other translation technologies.
History
Smartcat was originally developed as a CAT tool in 2012–2015 as an in-house solution by ABBYY Language Solutions (ABBYY LS), a linguistic service provider within the ABBYY group of companies. The impetus for its development was that ABBYY LS had "felt constrained by translation technologies that had existed for the last 15 years" and wanted an "intuitive, cloud-based, scalable, and powerful" solution that would let them manage projects with dozens of collaborators, including project managers, translators, editors, and other professionals.”
In 2016, Smartcat spun out of ABBYY LS to become a separate company and attracted $2.8 million in investments from Ilya Shirokov (ex-CEO at Odnoklassniki and founder of Yandex-acquired social network MoiKrug.ru). ABBYY LS’s founder and CEO Ivan Smolnikov also left the company to fully focus on Smartcat. The main reasons for the separation were that the "translation automation business turned out to be far from complementary to the services of language services providers" and that “some translation companies had been wary of using a service developed by a competitor.”
As of September 2020, the platform has more than 350,000 freelancers in its marketplace and provides an “app store” that allows users to integrate their Smartcat account with third-party tools.
Although Smartcat has an in-built CAT tool that helps translators work faster and more efficiently, its reach and functionality are much broader than that of a CAT tool. It is an all-in-one translation platform connecting businesses and translation professionals while offering additional services like payment automation, a combination the company brands as “Connected Translation”. For example, it allows translation agencies and LSPs to manage their businesses, including everything from searching for new vendors to managing international teams and centralizing international payments.
Monetization and subscription plans
Unlike most industry tools, Smartcat does not charge for user-based licenses, because it believes that counting seats just doesn’t fit in the translation business, where more than 90% of users in companies are freelancers and a varying number of them collaborate on projects on a daily basis.”
Instead, Smartcat’s monetization is primarily based on a percentage-based service fee on top of vendors’ own rates. Smartcat also offers paid subscriptions with some additional features, as well as vendor management and localization engineering support.
Connected Translation
Since early 2019, Smartcat has been using the term Connected Translation to refer to a connected localization ecosystem where businesses, agencies, and translators are combinedinto one content delivery loop. The connected translation model is made up of five key concepts: connectivity, translation, scalability, management, and automated payments:
Connectivity: interconnecting the content production and translation environments,
Translation: actually executing the translation job,
Scalability: sourcing new translation vendors if and when the need arises,
Management: having control over the process by tracking progress, reassigning vendors, etc.
Automated payments: sending bulk payments via a single invoice to any number of vendors in any location.
Document formats
Smartcat’s built-in CAT editor supports 70+ input formats, including text documents, presentations, spreadsheets, scanned documents and images (including a paid OCR service), HTML pages, resource files, industry-standard bilingual formats, and others. The platform also supports SDL Trados packages, which allows users to work on projects originally intended for SDL Trados, including generation of return packages to be further handled in Trados.
#LocFromHome
Smartcat is the organizer of the #LocFromHome online language industry conference. The conference is mostly focused on translation buyers and agencies and deals with up-and-coming challenges of the language industry. As of September 2020, there has been two runs of the event, each attracting around 2000 live attendees and featuring around 30 speakers.
References
External links
Official site
See also
vidby
Realivox
2015 software
Translation software
Computer-assisted translation | Smartcat | Technology | 887 |
2,509,631 | https://en.wikipedia.org/wiki/Dikaryon | The dikaryon (karyogamy) is a nuclear feature that is unique to certain fungi. (The green alga Derbesia had been long considered an exception, until the heterokaryotic hypothesis was challenged by later studies.) Compatible cell-types can fuse cytoplasms (plasmogamy). When this occurs, the two nuclei of two cells pair off and cohabit without fusing (karyogamy). This can be maintained for all the cells of the hyphae by synchronously dividing so that pairs are passed to newer cells. In the Ascomycota this attribute is most often found in the ascogenous hyphae and ascocarp while the bulk of the mycelium remains monokaryotic. In the Basidiomycota this is the dominant phase, with most Basidiomycota monokaryons weakly growing and short-lived.
The formation of a dikaryon is a plesiomorphic character for the subkingdom Dikarya, which consists of the Basidiomycota and the Ascomycota. The formation of croziers in the Ascomycota and of clamp connections in the Basidiomycota facilitates maintenance of the dikaryons. However, some fungi in each of these phyla have evolved other methods for maintaining the dikaryons, and therefore neither croziers nor clamp connections are ubiquitous in either phylum.
Etymology
The name dikaryon comes from the Greek δι- (di-) meaning "two" and κάρυον (karyon) meaning "nut", referring to the cell nucleus.
See also
Binucleated cells (as a pathological state)
Heterokaryon
Multinucleated cells
Syncytium
References
External links
Fungi Online Page, Formation of Dikaryons
Mycology | Dikaryon | Biology | 397 |
32,817,569 | https://en.wikipedia.org/wiki/AFDX-384 | AFDX-384 (BIBN-161) is a drug which acts as a selective antagonist of the muscarinic acetylcholine receptors, with selectivity for the M2 and M4 subtypes. It is used mainly for mapping the distribution of M2 and M4 muscarinic receptors in the brain, and studying their involvement in the development and treatment of dementia and schizophrenia.
See also
Pirenzepine (M1 selective antagonist)
References
M2 receptor antagonists
M4 receptor antagonists
Piperidines
Pyridobenzodiazepines
Ureas | AFDX-384 | Chemistry | 121 |
14,874,442 | https://en.wikipedia.org/wiki/EPHA6 | Ephrin type-A receptor 6 is a protein that in humans is encoded by the EPHA6 gene.
EphA6 may serve an important role in breast carcinogenesis and may pose as a novel prognostic indicator and therapeutic target for breast cancer, particularly in patients with steroid receptor negative expression and HER‑2 overexpression
References
Further reading
External links
Tyrosine kinase receptors | EPHA6 | Chemistry | 82 |
44,469 | https://en.wikipedia.org/wiki/Pluto | Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest known trans-Neptunian object by volume, by a small margin, but is less massive than Eris. Like other Kuiper belt objects, Pluto is made primarily of ice and rock and is much smaller than the inner planets. Pluto has roughly one-sixth the mass of the Moon, and one-third its volume.
Pluto has a moderately eccentric and inclined orbit, ranging from from the Sun. Light from the Sun takes 5.5 hours to reach Pluto at its orbital distance of . Pluto's eccentric orbit periodically brings it closer to the Sun than Neptune, but a stable orbital resonance prevents them from colliding.
Pluto has five known moons: Charon, the largest, whose diameter is just over half that of Pluto; Styx; Nix; Kerberos; and Hydra. Pluto and Charon are sometimes considered a binary system because the barycenter of their orbits does not lie within either body, and they are tidally locked. New Horizons was the first spacecraft to visit Pluto and its moons, making a flyby on July 14, 2015, and taking detailed measurements and observations.
Pluto was discovered in 1930 by Clyde W. Tombaugh, making it by far the first known object in the Kuiper belt. It was immediately hailed as the ninth planet. However, its planetary status was questioned when it was found to be much smaller than expected. These doubts increased following the discovery of additional objects in the Kuiper belt starting in the 1990s, and particularly the more massive scattered disk object Eris in 2005. In 2006, the International Astronomical Union (IAU) formally redefined the term planet to exclude dwarf planets such as Pluto. Many planetary astronomers, however, continue to consider Pluto and other dwarf planets to be planets.
History
Discovery
In the 1840s, Urbain Le Verrier used Newtonian mechanics to predict the position of the then-undiscovered planet Neptune after analyzing perturbations in the orbit of Uranus. Subsequent observations of Neptune in the late 19th century led astronomers to speculate that Uranus's orbit was being disturbed by another planet besides Neptune.
In 1906, Percival Lowell—a wealthy Bostonian who had founded Lowell Observatory in Flagstaff, Arizona, in 1894—started an extensive project in search of a possible ninth planet, which he termed "Planet X". By 1909, Lowell and William H. Pickering had suggested several possible celestial coordinates for such a planet. Lowell and his observatory conducted his search, using mathematical calculations made by Elizabeth Williams, until his death in 1916, but to no avail. Unknown to Lowell, his surveys had captured two faint images of Pluto on March 19 and April 7, 1915, but they were not recognized for what they were. There are fourteen other known precovery observations, with the earliest made by the Yerkes Observatory on August 20, 1909.
Percival's widow, Constance Lowell, entered into a ten-year legal battle with the Lowell Observatory over her husband's legacy, and the search for Planet X did not resume until 1929. Vesto Melvin Slipher, the observatory director, gave the job of locating Planet X to 23-year-old Clyde Tombaugh, who had just arrived at the observatory after Slipher had been impressed by a sample of his astronomical drawings.
Tombaugh's task was to systematically image the night sky in pairs of photographs, then examine each pair and determine whether any objects had shifted position. Using a blink comparator, he rapidly shifted back and forth between views of each of the plates to create the illusion of movement of any objects that had changed position or appearance between photographs. On February 18, 1930, after nearly a year of searching, Tombaugh discovered a possible moving object on photographic plates taken on January 23 and 29. A lesser-quality photograph taken on January 21 helped confirm the movement. After the observatory obtained further confirmatory photographs, news of the discovery was telegraphed to the Harvard College Observatory on March 13, 1930.
One Plutonian year corresponds to 247.94 Earth years; thus, in 2178, Pluto will complete its first orbit since its discovery.
Name and symbol
The name Pluto came from the Roman god of the underworld; and it is also an epithet for Hades (the Greek equivalent of Pluto).
Upon the announcement of the discovery, Lowell Observatory received over a thousand suggestions for names. Three names topped the list: Minerva, Pluto and Cronus. 'Minerva' was the Lowell staff's first choice but was rejected because it had already been used for an asteroid; Cronus was disfavored because it was promoted by an unpopular and egocentric astronomer, Thomas Jefferson Jackson See. A vote was then taken and 'Pluto' was the unanimous choice. To make sure the name stuck, and that the planet would not suffer changes in its name as Uranus had, Lowell Observatory proposed the name to the American Astronomical Society and the Royal Astronomical Society; both approved it unanimously. The name was published on May 1, 1930.
The name Pluto had received some 150 nominations among the letters and telegrams sent to Lowell. The first had been from Venetia Burney (1918–2009), an eleven-year-old schoolgirl in Oxford, England, who was interested in classical mythology. She had suggested it to her grandfather Falconer Madan when he read the news of Pluto's discovery to his family over breakfast; Madan passed the suggestion to astronomy professor Herbert Hall Turner, who cabled it to colleagues at Lowell on March 16, three days after the announcement.
The name 'Pluto' was mythologically appropriate: the god Pluto was one of six surviving children of Saturn, and the others had already all been chosen as names of major or minor planets (his brothers Jupiter and Neptune, and his sisters Ceres, Juno and Vesta). Both the god and the planet inhabited "gloomy" regions, and the god was able to make himself invisible, as the planet had been for so long.
The choice was further helped by the fact that the first two letters of Pluto were the initials of Percival Lowell; indeed, 'Percival' had been one of the more popular suggestions for a name for the new planet.
Pluto's planetary symbol was then created as a monogram of the letters "PL". This symbol is rarely used in astronomy anymore, though it is still common in astrology. However, the most common astrological symbol for Pluto, occasionally used in astronomy as well, is an orb (possibly representing Pluto's invisibility cap) over Pluto's bident , which dates to the early 1930s.
The name 'Pluto' was soon embraced by wider culture. In 1930, Walt Disney was apparently inspired by it when he introduced for Mickey Mouse a canine companion named Pluto, although Disney animator Ben Sharpsteen could not confirm why the name was given. In 1941, Glenn T. Seaborg named the newly created element plutonium after Pluto, in keeping with the tradition of naming elements after newly discovered planets, following uranium, which was named after Uranus, and neptunium, which was named after Neptune.
Most languages use the name "Pluto" in various transliterations. In Japanese, Houei Nojiri suggested the calque , and this was borrowed into Chinese and Korean. Some languages of India use the name Pluto, but others, such as Hindi, use the name of Yama, the God of Death in Hinduism. Polynesian languages also tend to use the indigenous god of the underworld, as in Māori Whiro.
Vietnamese might be expected to follow Chinese, but does not because the Sino-Vietnamese word 冥 minh "dark" is homophonous with 明 minh "bright". Vietnamese instead uses Yama, which is also a Buddhist deity, in the form of Sao Diêm Vương 星閻王 "Yama's Star", derived from Chinese 閻王 Yán Wáng / Yìhm Wòhng "King Yama".
Planet X disproved
Once Pluto was found, its faintness and lack of a viewable disc cast doubt on the idea that it was Lowell's Planet X. Estimates of Pluto's mass were revised downward throughout the 20th century.
Astronomers initially calculated its mass based on its presumed effect on Neptune and Uranus. In 1931, Pluto was calculated to be roughly the mass of Earth, with further calculations in 1948 bringing the mass down to roughly that of Mars. In 1976, Dale Cruikshank, Carl Pilcher and David Morrison of the University of Hawaiʻi calculated Pluto's albedo for the first time, finding that it matched that for methane ice; this meant Pluto had to be exceptionally luminous for its size and therefore could not be more than 1 percent the mass of Earth. (Pluto's albedo is times that of Earth.)
In 1978, the discovery of Pluto's moon Charon allowed the measurement of Pluto's mass for the first time: roughly 0.2% that of Earth, and far too small to account for the discrepancies in the orbit of Uranus. Subsequent searches for an alternative Planet X, notably by Robert Sutton Harrington, failed. In 1992, Myles Standish used data from Voyager 2'''s flyby of Neptune in 1989, which had revised the estimates of Neptune's mass downward by 0.5%—an amount comparable to the mass of Mars—to recalculate its gravitational effect on Uranus. With the new figures added in, the discrepancies, and with them the need for a Planet X, vanished. the majority of scientists agree that Planet X, as Lowell defined it, does not exist. Lowell had made a prediction of Planet X's orbit and position in 1915 that was fairly close to Pluto's actual orbit and its position at that time; Ernest W. Brown concluded soon after Pluto's discovery that this was a coincidence.
Classification
From 1992 onward, many bodies were discovered orbiting in the same volume as Pluto, showing that Pluto is part of a population of objects called the Kuiper belt. This made its official status as a planet controversial, with many questioning whether Pluto should be considered together with or separately from its surrounding population. Museum and planetarium directors occasionally created controversy by omitting Pluto from planetary models of the Solar System. In February 2000 the Hayden Planetarium in New York City displayed a Solar System model of only eight planets, which made headlines almost a year later.
Ceres, Pallas, Juno and Vesta lost their planet status among most astronomers after the discovery of many other asteroids in the 1840s. On the other hand, planetary geologists often regarded Ceres, and less often Pallas and Vesta, as being different from smaller asteroids because they were large enough to have undergone geological evolution. Although the first Kuiper belt objects discovered were quite small, objects increasingly closer in size to Pluto were soon discovered, some large enough (like Pluto itself) to satisfy geological but not dynamical ideas of planethood. On July 29, 2005, the debate became unavoidable when astronomers at Caltech announced the discovery of a new trans-Neptunian object, Eris, which was substantially more massive than Pluto and the most massive object discovered in the Solar System since Triton in 1846. Its discoverers and the press initially called it the tenth planet, although there was no official consensus at the time on whether to call it a planet. Others in the astronomical community considered the discovery the strongest argument for reclassifying Pluto as a minor planet.
IAU classification
The debate came to a head in August 2006, with an IAU resolution that created an official definition for the term "planet". According to this resolution, there are three conditions for an object in the Solar System to be considered a planet:
The object must be in orbit around the Sun.
The object must be massive enough to be rounded by its own gravity. More specifically, its own gravity should pull it into a shape defined by hydrostatic equilibrium.
It must have cleared the neighborhood around its orbit.
Pluto fails to meet the third condition. Its mass is substantially less than the combined mass of the other objects in its orbit: 0.07 times, in contrast to Earth, which is 1.7 million times the remaining mass in its orbit (excluding the moon). The IAU further decided that bodies that, like Pluto, meet criteria 1 and 2, but do not meet criterion 3 would be called dwarf planets. In September 2006, the IAU included Pluto, and Eris and its moon Dysnomia, in their Minor Planet Catalogue, giving them the official minor-planet designations "(134340) Pluto", "(136199) Eris", and "(136199) Eris I Dysnomia". Had Pluto been included upon its discovery in 1930, it would have likely been designated 1164, following 1163 Saga, which was discovered a month earlier.
There has been some resistance within the astronomical community toward the reclassification, and in particular planetary scientists often continue to reject it, considering Pluto, Charon, and Eris to be planets for the same reason they do so for Ceres. In effect, this amounts to accepting only the second clause of the IAU definition. Alan Stern, principal investigator with NASA's New Horizons mission to Pluto, derided the IAU resolution. He also stated that because less than five percent of astronomers voted for it, the decision was not representative of the entire astronomical community. Marc W. Buie, then at the Lowell Observatory, petitioned against the definition. Others have supported the IAU, for example Mike Brown, the astronomer who discovered Eris.
Public reception to the IAU decision was mixed. A resolution introduced in the California State Assembly facetiously called the IAU decision a "scientific heresy". The New Mexico House of Representatives passed a resolution in honor of Clyde Tombaugh, the discoverer of Pluto and a longtime resident of that state, that declared that Pluto will always be considered a planet while in New Mexican skies and that March 13, 2007, was Pluto Planet Day. The Illinois Senate passed a similar resolution in 2009 on the basis that Tombaugh was born in Illinois. The resolution asserted that Pluto was "unfairly downgraded to a 'dwarf' planet" by the IAU." Some members of the public have also rejected the change, citing the disagreement within the scientific community on the issue, or for sentimental reasons, maintaining that they have always known Pluto as a planet and will continue to do so regardless of the IAU decision. In 2006, in its 17th annual words-of-the-year vote, the American Dialect Society voted plutoed as the word of the year. To "pluto" is to "demote or devalue someone or something". In April 2024, Arizona (where Pluto was first discovered in 1930) passed a law naming Pluto as the official state planet.
Researchers on both sides of the debate gathered in August 2008, at the Johns Hopkins University Applied Physics Laboratory for a conference that included back-to-back talks on the IAU definition of a planet. Entitled "The Great Planet Debate", the conference published a post-conference press release indicating that scientists could not come to a consensus about the definition of planet. In June 2008, the IAU had announced in a press release that the term "plutoid" would henceforth be used to refer to Pluto and other planetary-mass objects that have an orbital semi-major axis greater than that of Neptune, though the term has not seen significant use.
Orbit
Pluto's orbital period is about 248 years. Its orbital characteristics are substantially different from those of the planets, which follow nearly circular orbits around the Sun close to a flat reference plane called the ecliptic. In contrast, Pluto's orbit is moderately inclined relative to the ecliptic (over 17°) and moderately eccentric (elliptical). This eccentricity means a small region of Pluto's orbit lies closer to the Sun than Neptune's. The Pluto–Charon barycenter came to perihelion on September 5, 1989, and was last closer to the Sun than Neptune between February 7, 1979, and February 11, 1999.
Although the 3:2 resonance with Neptune (see below) is maintained, Pluto's inclination and eccentricity behave in a chaotic manner. Computer simulations can be used to predict its position for several million years (both forward and backward in time), but after intervals much longer than the Lyapunov time of 10–20 million years, calculations become unreliable: Pluto is sensitive to immeasurably small details of the Solar System, hard-to-predict factors that will gradually change Pluto's position in its orbit.
The semi-major axis of Pluto's orbit varies between about 39.3 and 39.6 AU with a period of about 19,951 years, corresponding to an orbital period varying between 246 and 249 years. The semi-major axis and period are presently getting longer.
Relationship with Neptune
Despite Pluto's orbit appearing to cross that of Neptune when viewed from north or south of the Solar System, the two objects' orbits do not intersect. When Pluto is closest to the Sun, and close to Neptune's orbit as viewed from such a position, it is also the farthest north of Neptune's path. Pluto's orbit passes about 8 AU north of that of Neptune, preventing a collision.
This alone is not enough to protect Pluto; perturbations from the planets (especially Neptune) could alter Pluto's orbit (such as its orbital precession) over millions of years so that a collision could happen. However, Pluto is also protected by its 2:3 orbital resonance with Neptune: for every two orbits that Pluto makes around the Sun, Neptune makes three, in a frame of reference that rotates at the rate that Pluto's perihelion precesses (about degrees per year). Each cycle lasts about 495 years. (There are many other objects in this same resonance, called plutinos.) At present, in each 495-year cycle, the first time Pluto is at perihelion (such as in 1989), Neptune is 57° ahead of Pluto. By Pluto's second passage through perihelion, Neptune will have completed a further one and a half of its own orbits, and will be 123° behind Pluto. Pluto and Neptune's minimum separation is over 17 AU, which is greater than Pluto's minimum separation from Uranus (11 AU). The minimum separation between Pluto and Neptune actually occurs near the time of Pluto's aphelion.
The 2:3 resonance between the two bodies is highly stable and has been preserved over millions of years. This prevents their orbits from changing relative to one another, so the two bodies can never pass near each other. Even if Pluto's orbit were not inclined, the two bodies could never collide. When Pluto's period is slightly different from 3/2 of Neptune's, the pattern of its distance from Neptune will drift. Near perihelion Pluto moves interior to Neptune's orbit and is therefore moving faster, so during the first of two orbits in the 495-year cycle, it is approaching Neptune from behind. At present it remains between 50° and 65° behind Neptune for 100 years (e.g. 1937–2036). The gravitational pull between the two causes angular momentum to be transferred to Pluto. This situation moves Pluto into a slightly larger orbit, where it has a slightly longer period, according to Kepler's third law. After several such repetitions, Pluto is sufficiently delayed that at the second perihelion of each cycle it will not be far ahead of Neptune coming behind it, and Neptune will start to decrease Pluto's period again. The whole cycle takes about 20,000 years to complete.
Other factors
Numerical studies have shown that over millions of years, the general nature of the alignment between the orbits of Pluto and Neptune does not change. There are several other resonances and interactions that enhance Pluto's stability. These arise principally from two additional mechanisms (besides the 2:3 mean-motion resonance).
First, Pluto's argument of perihelion, the angle between the point where it crosses the ecliptic (or the invariant plane) and the point where it is closest to the Sun, librates around 90°. This means that when Pluto is closest to the Sun, it is at its farthest north of the plane of the Solar System, preventing encounters with Neptune. This is a consequence of the Kozai mechanism, which relates the eccentricity of an orbit to its inclination to a larger perturbing body—in this case, Neptune. Relative to Neptune, the amplitude of libration is 38°, and so the angular separation of Pluto's perihelion to the orbit of Neptune is always greater than 52° . The closest such angular separation occurs every 10,000 years.
Second, the longitudes of ascending nodes of the two bodies—the points where they cross the invariant plane—are in near-resonance with the above libration. When the two longitudes are the same—that is, when one could draw a straight line through both nodes and the Sun—Pluto's perihelion lies exactly at 90°, and hence it comes closest to the Sun when it is furthest north of Neptune's orbit. This is known as the 1:1 superresonance. All the Jovian planets (Jupiter, Saturn, Uranus, and Neptune) play a role in the creation of the superresonance.
Orcus
The second-largest known plutino, Orcus, has a diameter around 900 km and is in a very similar orbit to that of Pluto. However, the orbits of Pluto and Orcus are out of phase, so that the two never approach each other. It has been termed the "anti-Pluto", and is named for the Etruscan counterpart to the god Pluto.
Rotation
Pluto's rotation period, its day, is equal to 6.387 Earth days. Like Uranus and 2 Pallas, Pluto rotates on its "side" in its orbital plane, with an axial tilt of 120°, and so its seasonal variation is extreme; at its solstices, one-fourth of its surface is in continuous daylight, whereas another fourth is in continuous darkness. The reason for this unusual orientation has been debated. Research from the University of Arizona has suggested that it may be due to the way that a body's spin will always adjust to minimize energy. This could mean a body reorienting itself to put extraneous mass near the equator and regions lacking mass tend towards the poles. This is called polar wander. According to a paper released from the University of Arizona, this could be caused by masses of frozen nitrogen building up in shadowed areas of the dwarf planet. These masses would cause the body to reorient itself, leading to its unusual axial tilt of 120°. The buildup of nitrogen is due to Pluto's vast distance from the Sun. At the equator, temperatures can drop to , causing nitrogen to freeze as water would freeze on Earth. The same polar wandering effect seen on Pluto would be observed on Earth were the Antarctic ice sheet several times larger.
Geology
Surface
The plains on Pluto's surface are composed of more than 98 percent nitrogen ice, with traces of methane and carbon monoxide. Nitrogen and carbon monoxide are most abundant on the anti-Charon face of Pluto (around 180° longitude, where Tombaugh Regio's western lobe, Sputnik Planitia, is located), whereas methane is most abundant near 300° east. The mountains are made of water ice. Pluto's surface is quite varied, with large differences in both brightness and color. Pluto is one of the most contrastive bodies in the Solar System, with as much contrast as Saturn's moon Iapetus. The color varies from charcoal black, to dark orange and white. Pluto's color is more similar to that of Io with slightly more orange and significantly less red than Mars. Notable geographical features include Tombaugh Regio, or the "Heart" (a large bright area on the side opposite Charon), Belton Regio, or the "Whale" (a large dark area on the trailing hemisphere), and the "Brass Knuckles" (a series of equatorial dark areas on the leading hemisphere).
Sputnik Planitia, the western lobe of the "Heart", is a 1,000 km-wide basin of frozen nitrogen and carbon monoxide ices, divided into polygonal cells, which are interpreted as convection cells that carry floating blocks of water ice crust and sublimation pits towards their margins; there are obvious signs of glacial flows both into and out of the basin. It has no craters that were visible to New Horizons, indicating that its surface is less than 10 million years old. Latest studies have shown that the surface has an age of years.
The New Horizons science team summarized initial findings as "Pluto displays a surprisingly wide variety of geological landforms, including those resulting from glaciological and surface–atmosphere interactions as well as impact, tectonic, possible cryovolcanic, and mass-wasting processes."
In Western parts of Sputnik Planitia there are fields of transverse dunes formed by the winds blowing from the center of Sputnik Planitia in the direction of surrounding mountains. The dune wavelengths are in the range of 0.4–1 km and likely consist of methane particles 200–300 μm in size.
Internal structure
Pluto's density is . Because the decay of radioactive elements would eventually heat the ices enough for the rock to separate from them, scientists expect that Pluto's internal structure is differentiated, with the rocky material having settled into a dense core surrounded by a mantle of water ice. The pre–New Horizons estimate for the diameter of the core is , 70% of Pluto's diameter.
It is possible that such heating continues, creating a subsurface ocean of liquid water thick at the core–mantle boundary. In September 2016, scientists at Brown University simulated the impact thought to have formed Sputnik Planitia, and showed that it might have been the result of liquid water upweling from below after the collision, implying the existence of a subsurface ocean at least 100 km deep. In June 2020, astronomers reported evidence that Pluto may have had a subsurface ocean, and consequently may have been habitable, when it was first formed. In March 2022, a team of researchers proposed that the mountains Wright Mons and Piccard Mons are actually a merger of many smaller cryovolcanic domes, suggesting a source of heat on the body at levels previously thought not possible.
Mass and size
Pluto's diameter is and its mass is , 17.7% that of the Moon (0.22% that of Earth). Its surface area is , or just slightly bigger than Russia or Antarctica (particularly including the Antarctic sea ice during winter). Its surface gravity is 0.063 g (compared to 1 g for Earth and 0.17 g for the Moon). This gives Pluto an escape velocity of 4,363.2 km per hour / 2,711.167 miles per hour (as compared to Earth's 40,270 km per hour / 25,020 miles per hour). Pluto is more than twice the diameter and a dozen times the mass of Ceres, the largest object in the asteroid belt. It is less massive than the dwarf planet Eris, a trans-Neptunian object discovered in 2005, though Pluto has a larger diameter of 2,376.6 km compared to Eris's approximate diameter of 2,326 km.
With less than 0.2 lunar masses, Pluto is much less massive than the terrestrial planets, and also less massive than seven moons: Ganymede, Titan, Callisto, Io, the Moon, Europa, and Triton. The mass is much less than thought before Charon was discovered.
The discovery of Pluto's satellite Charon in 1978 enabled a determination of the mass of the Pluto–Charon system by application of Newton's formulation of Kepler's third law. Observations of Pluto in occultation with Charon allowed scientists to establish Pluto's diameter more accurately, whereas the invention of adaptive optics allowed them to determine its shape more accurately.
Determinations of Pluto's size have been complicated by its atmosphere and hydrocarbon haze. In March 2014, Lellouch, de Bergh et al. published findings regarding methane mixing ratios in Pluto's atmosphere consistent with a Plutonian diameter greater than 2,360 km, with a "best guess" of 2,368 km. On July 13, 2015, images from NASA's New Horizons mission Long Range Reconnaissance Imager (LORRI), along with data from the other instruments, determined Pluto's diameter to be , which was later revised to be on July 24, and later to . Using radio occultation data from the New Horizons Radio Science Experiment (REX), the diameter was found to be .
Atmosphere
Pluto has a tenuous atmosphere consisting of nitrogen (N2), methane (CH4), and carbon monoxide (CO), which are in equilibrium with their ices on Pluto's surface. According to the measurements by New Horizons, the surface pressure is about 1 Pa (10 μbar), roughly one million to 100,000 times less than Earth's atmospheric pressure. It was initially thought that, as Pluto moves away from the Sun, its atmosphere should gradually freeze onto the surface; studies of New Horizons data and ground-based occultations show that Pluto's atmospheric density increases, and that it likely remains gaseous throughout Pluto's orbit. New Horizons observations showed that atmospheric escape of nitrogen to be 10,000 times less than expected. Alan Stern has contended that even a small increase in Pluto's surface temperature can lead to exponential increases in Pluto's atmospheric density; from 18 hPa to as much as 280 hPa (three times that of Mars to a quarter that of the Earth). At such densities, nitrogen could flow across the surface as liquid. Just like sweat cools the body as it evaporates from the skin, the sublimation of Pluto's atmosphere cools its surface. Pluto has no or almost no troposphere; observations by New Horizons suggest only a thin tropospheric boundary layer. Its thickness in the place of measurement was 4 km, and the temperature was 37±3 K. The layer is not continuous.
In July 2019, an occultation by Pluto showed that its atmospheric pressure, against expectations, had fallen by 20% since 2016. In 2021, astronomers at the Southwest Research Institute confirmed the result using data from an occultation in 2018, which showed that light was appearing less gradually from behind Pluto's disc, indicating a thinning atmosphere.
The presence of methane, a powerful greenhouse gas, in Pluto's atmosphere creates a temperature inversion, with the average temperature of its atmosphere tens of degrees warmer than its surface, though observations by New Horizons have revealed Pluto's upper atmosphere to be far colder than expected (70 K, as opposed to about 100 K). Pluto's atmosphere is divided into roughly 20 regularly spaced haze layers up to 150 km high, thought to be the result of pressure waves created by airflow across Pluto's mountains.
Natural satellites
Pluto has five known natural satellites. The largest and closest to Pluto is Charon. First identified in 1978 by astronomer James Christy, Charon is the only moon of Pluto that may be in hydrostatic equilibrium. Charon's mass is sufficient to cause the barycenter of the Pluto–Charon system to be outside Pluto. Beyond Charon there are four much smaller circumbinary moons. In order of distance from Pluto they are Styx, Nix, Kerberos, and Hydra. Nix and Hydra were both discovered in 2005, Kerberos was discovered in 2011, and Styx was discovered in 2012. The satellites' orbits are circular (eccentricity < 0.006) and coplanar with Pluto's equator (inclination < 1°), and therefore tilted approximately 120° relative to Pluto's orbit. The Plutonian system is highly compact: the five known satellites orbit within the inner 3% of the region where prograde orbits would be stable.
The orbital periods of all Pluto's moons are linked in a system of orbital resonances and near-resonances. When precession is accounted for, the orbital periods of Styx, Nix, and Hydra are in an exact 18:22:33 ratio. There is a sequence of approximate ratios, 3:4:5:6, between the periods of Styx, Nix, Kerberos, and Hydra with that of Charon; the ratios become closer to being exact the further out the moons are.
The Pluto–Charon system is one of the few in the Solar System whose barycenter lies outside the primary body; the Patroclus–Menoetius system is a smaller example, and the Sun–Jupiter system is the only larger one. The similarity in size of Charon and Pluto has prompted some astronomers to call it a double dwarf planet. The system is also unusual among planetary systems in that each is tidally locked to the other, which means that Pluto and Charon always have the same hemisphere facing each other — a property shared by only one other known system, Eris and Dysnomia. From any position on either body, the other is always at the same position in the sky, or always obscured. This also means that the rotation period of each is equal to the time it takes the entire system to rotate around its barycenter.
Pluto's moons are hypothesized to have been formed by a collision between Pluto and a similar-sized body, early in the history of the Solar System. The collision released material that consolidated into the moons around Pluto.
Quasi-satellite
In 2012, it was calculated that 15810 Arawn could be a quasi-satellite of Pluto, a specific type of co-orbital configuration. According to the calculations, the object would be a quasi-satellite of Pluto for about 350,000 years out of every two-million-year period. Measurements made by the New Horizons spacecraft in 2015 made it possible to calculate the orbit of Arawn more accurately, and confirmed the earlier ones. However, it is not agreed upon among astronomers whether Arawn should be classified as a quasi-satellite of Pluto based on its orbital dynamics, since its orbit is primarily controlled by Neptune with only occasional perturbations by Pluto.
Origin
Pluto's origin and identity had long puzzled astronomers. One early hypothesis was that Pluto was an escaped moon of Neptune knocked out of orbit by Neptune's largest moon, Triton. This idea was eventually rejected after dynamical studies showed it to be impossible because Pluto never approaches Neptune in its orbit.
Pluto's true place in the Solar System began to reveal itself only in 1992, when astronomers began to find small icy objects beyond Neptune that were similar to Pluto not only in orbit but also in size and composition. This trans-Neptunian population is thought to be the source of many short-period comets. Pluto is the largest member of the Kuiper belt, a stable belt of objects located between 30 and 50 AU from the Sun. As of 2011, surveys of the Kuiper belt to magnitude 21 were nearly complete and any remaining Pluto-sized objects are expected to be beyond 100 AU from the Sun. Like other Kuiper-belt objects (KBOs), Pluto shares features with comets; for example, the solar wind is gradually blowing Pluto's surface into space. It has been claimed that if Pluto were placed as near to the Sun as Earth, it would develop a tail, as comets do. This claim has been disputed with the argument that Pluto's escape velocity is too high for this to happen. It has been proposed that Pluto may have formed as a result of the agglomeration of numerous comets and Kuiper-belt objects.
Though Pluto is the largest Kuiper belt object discovered, Neptune's moon Triton, which is larger than Pluto, is similar to it both geologically and atmospherically, and is thought to be a captured Kuiper belt object. Eris (see above) is about the same size as Pluto (though more massive) but is not strictly considered a member of the Kuiper belt population. Rather, it is considered a member of a linked population called the scattered disc.
Like other members of the Kuiper belt, Pluto is thought to be a residual planetesimal; a component of the original protoplanetary disc around the Sun that failed to fully coalesce into a full-fledged planet. Most astronomers agree that Pluto owes its position to a sudden migration undergone by Neptune early in the Solar System's formation. As Neptune migrated outward, it approached the objects in the proto-Kuiper belt, setting one in orbit around itself (Triton), locking others into resonances, and knocking others into chaotic orbits. The objects in the scattered disc, a dynamically unstable region overlapping the Kuiper belt, are thought to have been placed in their positions by interactions with Neptune's migrating resonances. A computer model created in 2004 by Alessandro Morbidelli of the Observatoire de la Côte d'Azur in Nice suggested that the migration of Neptune into the Kuiper belt may have been triggered by the formation of a 1:2 resonance between Jupiter and Saturn, which created a gravitational push that propelled both Uranus and Neptune into higher orbits and caused them to switch places, ultimately doubling Neptune's distance from the Sun. The resultant expulsion of objects from the proto-Kuiper belt could also explain the Late Heavy Bombardment 600 million years after the Solar System's formation and the origin of the Jupiter trojans. It is possible that Pluto had a near-circular orbit about 33 AU from the Sun before Neptune's migration perturbed it into a resonant capture. The Nice model requires that there were about a thousand Pluto-sized bodies in the original planetesimal disk, which included Triton and Eris.
Observation and exploration
Observation
Pluto's distance from Earth makes its in-depth study and exploration difficult. Pluto's visual apparent magnitude averages 15.1, brightening to 13.65 at perihelion. To see it, a telescope is required; around 30 cm (12 in) aperture being desirable. It looks star-like and without a visible disk even in large telescopes, because its angular diameter is maximum 0.11".
The earliest maps of Pluto, made in the late 1980s, were brightness maps created from close observations of eclipses by its largest moon, Charon. Observations were made of the change in the total average brightness of the Pluto–Charon system during the eclipses. For example, eclipsing a bright spot on Pluto makes a bigger total brightness change than eclipsing a dark spot. Computer processing of many such observations can be used to create a brightness map. This method can also track changes in brightness over time.
Better maps were produced from images taken by the Hubble Space Telescope (HST), which offered higher resolution, and showed considerably more detail, resolving variations several hundred kilometers across, including polar regions and large bright spots. These maps were produced by complex computer processing, which finds the best-fit projected maps for the few pixels of the Hubble images. These remained the most detailed maps of Pluto until the flyby of New Horizons in July 2015, because the two cameras on the HST used for these maps were no longer in service.
Exploration
The New Horizons spacecraft, which flew by Pluto in July 2015, is the first and so far only attempt to explore Pluto directly. Launched in 2006, it captured its first (distant) images of Pluto in late September 2006 during a test of the Long Range Reconnaissance Imager. The images, taken from a distance of approximately 4.2 billion kilometers, confirmed the spacecraft's ability to track distant targets, critical for maneuvering toward Pluto and other Kuiper belt objects. In early 2007 the craft made use of a gravity assist from Jupiter.New Horizons made its closest approach to Pluto on July 14, 2015, after a 3,462-day journey across the Solar System. Scientific observations of Pluto began five months before the closest approach and continued for at least a month after the encounter. Observations were conducted using a remote sensing package that included imaging instruments and a radio science investigation tool, as well as spectroscopic and other experiments. The scientific goals of New Horizons were to characterize the global geology and morphology of Pluto and its moon Charon, map their surface composition, and analyze Pluto's neutral atmosphere and its escape rate. On October 25, 2016, at 05:48 pm ET, the last bit of data (of a total of 50 billion bits of data; or 6.25 gigabytes) was received from New Horizons from its close encounter with Pluto.
Since the New Horizons flyby, scientists have advocated for an orbiter mission that would return to Pluto to fulfill new science objectives. They include mapping the surface at per pixel, observations of Pluto's smaller satellites, observations of how Pluto changes as it rotates on its axis, investigations of a possible subsurface ocean, and topographic mapping of Pluto's regions that are covered in long-term darkness due to its axial tilt. The last objective could be accomplished using laser pulses to generate a complete topographic map of Pluto. New Horizons principal investigator Alan Stern has advocated for a Cassini-style orbiter that would launch around 2030 (the 100th anniversary of Pluto's discovery) and use Charon's gravity to adjust its orbit as needed to fulfill science objectives after arriving at the Pluto system. The orbiter could then use Charon's gravity to leave the Pluto system and study more KBOs after all Pluto science objectives are completed. A conceptual study funded by the NASA Innovative Advanced Concepts (NIAC) program describes a fusion-enabled Pluto orbiter and lander based on the Princeton field-reversed configuration reactor.Fusion-Enabled Pluto Orbiter and Lander – Phase I Final Report . (PDF) Stephanie Thomas, Princeton Satellite Systems. 2017.New Horizons imaged all of Pluto's northern hemisphere, and the equatorial regions down to about 30° South. Higher southern latitudes have only been observed, at very low resolution, from Earth. Images from the Hubble Space Telescope in 1996 cover 85% of Pluto and show large albedo features down to about 75° South. This is enough to show the extent of the temperate-zone maculae. Later images had slightly better resolution, due to minor improvements in Hubble instrumentation. The equatorial region of the sub-Charon hemisphere of Pluto has only been imaged at low resolution, as New Horizons made its closest approach to the anti-Charon hemisphere.
Some albedo variations in the higher southern latitudes could be detected by New Horizons using Charon-shine (light reflected off Charon). The south polar region seems to be darker than the north polar region, but there is a high-albedo region in the southern hemisphere that may be a regional nitrogen or methane ice deposit.
See also
How I Killed Pluto and Why It Had It Coming''
List of geological features on Pluto
Pluto in astrology
Pluto in fiction
Stats of planets in the Solar System
Notes
References
Further reading
External links
New Horizons homepage
Pluto Profile at NASA's Solar System Exploration site
NASA Pluto factsheet
Website of the observatory that discovered Pluto
Earth telescope image of Pluto system
Keck infrared with AO of Pluto system
Video – Pluto – viewed through the years (GIF) (NASA; animation; July 15, 2015).
Video – Pluto – "FlyThrough" (00:22; MP4) (YouTube) (NASA; animation; August 31, 2015).
"A Day on Pluto Video made from July 2015 New Horizon Images" Scientific American
NASA CGI video of Pluto flyover (July 14, 2017)
CGI video simulation of rotating Pluto by Seán Doran (see album for more)
Google Pluto 3D , interactive map of the dwarf planet
Articles containing video clips
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Discoveries by Clyde Tombaugh
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Dwarf planets
Kozai mechanism
Minor planets visited by spacecraft
Pluto
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Plutinos
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Solar System | Pluto | Astronomy | 9,160 |
50,343,535 | https://en.wikipedia.org/wiki/Witnesses%20%282018%20film%29 | Witnesses is a historical drama directed by Konstantin Fam, consisting of three novellas "Shoes", "Brutus" and "Violin", united by a common concept and dedicated to the memory of Holocaust victims. Also known as The Trilogy "Witnesses".
Concept
The aim of the project is the story of the tragic events of 1933–1945 years and a reminder to the younger generation of the tragedy with the aim of preventing it in the future.
Konstantin Fam:
-This film I dedicate to the memory of their relatives who were killed or went missing during the Second World War, as well as the memory of the six million victims of the Holocaust. I wholeheartedly wish that such a tragedy does not happen again.
A notable feature of the film is its novel structure and the fact that each of the novels had its own unique stories and history of success on film festivals. "Shoes", "Brutus" and "Violin" - all parts of the film were longlisted for the Academy Award for "Best Live Action Short Film" and became the winners of many Russian and international film festivals.
History of creation
In 2012 it was created the short film "Shoes", dedicated to the memory of the Holocaust, which was warmly welcomed by the audience and the festival was a success. The film's director Konstantin Fam, decided to develop the idea of "unusual sight" to the Holocaust and to create a full-length film "Witnesses", which in addition to "shoes" will include two more novels -
"Brutus" and "Violin".
Presentation the Trilogy was held at the 66th Cannes Film Festival, which is also under the Short Film Corner, were shown the presentation materials to the novel "Brutus."
The producer group the Trilogy includes filmmakers from Russia, Belarus, Israel and the United States.
November 9 at the 34th American Film Market held a unique special pitching new projects. Film "Witnesses" with the support ROSKINO became the only Russian project, presented at the pitching.
The film was created with the financial support of the Ministry for Culture of Russia, as well as private philanthropists.
"Shoes"
"Shoes" The film is the first novel of the Trilogy "Witnesses". The film is set in the 1930s-1940s and tells the story of a pair of women's shoes, which story begins in a shop window and was tragically cut short in a mass grave footwear concentration camp "Auschwitz."
In the story "Shoes" is the main character shoes - women's shoes. In the picture is not visible persons and the lack of dialogue. The entire film is accompanied by an original symphonic music.
The shooting of the film took place on the territory of Belarus, Poland, Czech Republic and France. The picture was a success of the festival, both in Russia and abroad.
The only Russian short film nominated for the Academy Award in 2013.
"Brutus"
Events in the film "Brutus" (from a story by Ludvik Ashkenazy) are shown through the dog's eyes. This particular view allows you to see the different human values. War, racial laws, human cruelty have separated a German shepherd by the name Brutus with his owner. From kennel it as a watchdog gets to a concentration camp, where in the process of training and psychological manipulation a harmless pet becomes a killer dog. One day Brutus is commanded to chase and kill Jewish escapees, amongst whom he encounters his former owner...
There it was reported that the main role in the film can fulfill one of Hollywood actresses, do not hide their Jewish ancestry - Mila Kunis and Natalie Portman
June 27, 2013 "Brutus" won a screenwriting pitching the 35th Moscow International Film Festival and received a grant from the Russian Cinematographers' Union. Of the 418 applications submitted for the competition by the selection committee of the Youth Center made the long list of 22 projects of full-length feature films and television projects and 23 short film project.
Special guest and expert Pitching was Nikita Mikhalkov.
The script for "Brutus" wrote Sergei Rachlin - the first Russian journalist, received the Association of the Hollywood Foreign Press, today - the executive secretary of the award "Golden Globe".
Film premiered at the Moscow International Film Festival in June 2016.
"Violin"
World of third novel "Violin" entirely revolves around the unique musical instrument. The third story, "Violin" (from a story by Yossi Tavora) tells about the amazing violin fate, passed through all the horrors of war. The story begins in a violin workshop in Nuremberg, where at the beginning of the 20th century, was created a violin, intended as a gift to the Jewish boy, and ends with a hundred years later concert at the Wailing Wall.
Film premiered as part of the competition program of the 39th Moscow International Film Festival in June 2017. It is also longlisted for the Academy Award for Live Action Short Film and won the award of the name of Vera Glagoleva in Sochi International Film Awards
Partners
Federation of Jewish Communities of Russia
Russian Jewish Congress
Chabad Odesa
Documentary Film Center
Youth Center of the Union of Cinematographers of the Russian Federation
ROSKINO
See also
Shoes (2012 film)
Brutus (2016 film)
Violin (2017 film)
References
External links
Holocaust films
Russian epic films
Russian war drama films
Russian-language war drama films
2010s Russian films
2010s Russian-language films
War epic films
Epic films based on actual events
Rescue of Jews during the Holocaust
Russian World War II films | Witnesses (2018 film) | Biology | 1,122 |
11,821,775 | https://en.wikipedia.org/wiki/Poles%20of%20astronomical%20bodies | The poles of astronomical bodies are determined based on their axis of rotation in relation to the celestial poles of the celestial sphere. Astronomical bodies include stars, planets, dwarf planets and small Solar System bodies such as comets and minor planets (e.g., asteroids), as well as natural satellites and minor-planet moons.
Poles of rotation
The International Astronomical Union (IAU) defines the north pole of a planet or any of its satellites in the Solar System as the planetary pole that is in the same celestial hemisphere, relative to the invariable plane of the Solar System, as Earth's north pole. This definition is independent of the object's direction of rotation about its axis. This implies that an object's direction of rotation, when viewed from above its north pole, may be either clockwise or counterclockwise. The direction of rotation exhibited by most objects in the solar system (including Sun and Earth) is counterclockwise. Venus rotates clockwise, and Uranus has been knocked on its side and rotates almost perpendicular to the rest of the Solar System. The ecliptic remains within 3° of the invariable plane over five million years, but is now inclined about 23.44° to Earth's celestial equator used for the coordinates of poles. This large inclination means that the declination of a pole relative to Earth's celestial equator could be negative even though a planet's north pole (such as Uranus's) is north of the invariable plane.
In 2009 the responsible IAU Working Group decided to define the poles of dwarf planets, minor planets, their satellites, and comets according to the right-hand rule. To avoid confusion with the "north" and "south" definitions relative to the invariable plane, the poles are called "positive" and "negative." The positive pole is the pole toward which the thumb points when the fingers of the right hand are curled in its direction of rotation. The negative pole is the pole toward which the thumb points when the fingers of the left hand are curled in its direction of rotation. This change was needed because the poles of some asteroids and comets precess rapidly enough for their north and south poles to swap within a few decades using the invariable plane definition.
The projection of a planet's north pole onto the celestial sphere gives its north celestial pole. The location of the celestial poles of some selected Solar System objects is shown in the following table. The coordinates are given relative to Earth's celestial equator and the vernal equinox as they existed at J2000 (2000 January 1 12:00:00 TT) which is a plane fixed in inertial space now called the International Celestial Reference Frame (ICRF). Many poles precess or otherwise move relative to the ICRF, so their coordinates will change. The Moon's poles are particularly mobile.
Some bodies in the Solar System, including Saturn's moon Hyperion and the asteroid 4179 Toutatis, lack a stable north pole. They rotate chaotically because of their irregular shape and gravitational influences from nearby planets and moons, and as a result the instantaneous pole wanders over their surface, and may momentarily vanish altogether (when the object comes to a standstill with respect to the distant stars).
Magnetic poles
Planetary magnetic poles are defined analogously to the Earth's North and South magnetic poles: they are the locations on the planet's surface at which the planet's magnetic field lines are vertical. The direction of the field determines whether the pole is a magnetic north or south pole, exactly as on Earth. The Earth's magnetic axis is approximately aligned with its rotational axis, meaning that the geomagnetic poles are relatively close to the geographic poles. However, this is not necessarily the case for other planets; the magnetic axis of Uranus, for example, is inclined by as much as 60°.
Orbital pole
In addition to the rotational pole, a planet's orbit also has a defined direction in space. The direction of the angular momentum vector of that orbit can be defined as an orbital pole. Earth's orbital pole, i.e. the ecliptic pole, points in the direction of the constellation Draco.
Near, far, leading and trailing poles
In the particular (but frequent) case of synchronous satellites, four more poles can be defined. They are the near, far, leading, and trailing poles. For example, Io, one of the moons of Jupiter, rotates synchronously, so its orientation with respect to Jupiter stays constant. There will be a single, unmoving point of its surface where Jupiter is at the zenith, exactly overhead – this is the near pole, also called the sub- or pro-Jovian point. At the antipode of this point is the far pole, where Jupiter lies at the nadir; it is also called the anti-Jovian point. There will also be a single unmoving point which is farthest along Io's orbit (best defined as the point most removed from the plane formed by the north-south and near-far axes, on the leading side) – this is the leading pole. At its antipode lies the trailing pole. Io can thus be divided into north and south hemispheres, into pro- and anti-Jovian hemispheres, and into leading and trailing hemispheres. These poles are mean poles because the points are not, strictly speaking, unmoving: there is continuous libration about the mean orientation, because Io's orbit is slightly eccentric and the gravity of the other moons disturbs it regularly.
See also
Galactic coordinate system
Planetary coordinate system
References
Astronomical coordinate systems
Astronomical objects | Poles of astronomical bodies | Physics,Astronomy,Mathematics | 1,166 |
57,756,380 | https://en.wikipedia.org/wiki/Red%20nugget | Red nuggets is the nickname given to rare, unusually small galaxies packed with large amounts of red stars that were originally observed by the Hubble Space Telescope in 2005. They are ancient remnants of the first massive galaxies. The environments of red nuggets are usually consistent with the general elliptical galaxy population. Most red nuggets have merged with other galaxies, but some managed to stay unscathed.
Naming
Red nuggets are not only nicknamed for their size and color, but also for how precious the discovery is to astronomers as it challenged current theories regarding galaxy formation at the time the term was coined on.
Formation of red nuggets
Red nuggets are formed from blue nuggets. Blue nuggets are early, stream-fed, star-forming systems that are quenched inside-out within the inner kiloparsec (kpc) and dissipatively compacted into red nuggets at their peak of gas compaction. The compaction of the blue nugget happens at an approximately constant specific star formation rate (or SFR). The quenching of the blue nugget happens at a completely constant stellar surface density. Galaxies with more mass quench earlier than galaxies with low amounts of mass because galaxies with low amounts of mass try to quench several times. The compaction happens due to a fierce period of inflow involving (mostly small) mergers and counter-rotating streams or recycled gas. It is also frequently associated with extreme disc instability. The quenching happens because of the extremely high SFR, stellar and supernova feedback, and possibly also active galactic nuclei feedback due to the high gas density in the center of the red nugget.
Star formation
Data from NASA's Chandra X-Ray Observatory observing the red nuggets Mrk 1216 and PGC 032673 has shown that the central black holes suppress star formation in red nuggets with their heat and feed on the gas surrounding them. This brings up the intriguing question on how they could possibly be packed so densely with stars. Results show that red nuggets may have untapped stellar "fuel" to produce their unusually large number of stars. Another theory says that red nuggets are young elliptical galaxies, therefore forming the same way those do.
Sloan Digital Sky Survey
A team led by Ivana Damjanov found over 600 red nugget candidates in the Sloan Digital Sky Survey (SDSS) database, of which 9 were confirmed as red nuggets. These red nuggets have been missed so long because, due to their extremely small size, they look like stars in pictures. But their spectra shows what they really are. Damjanov expressed how truly amazing the discovery was when she said, "Looking for 'red nuggets' in the Sloan Digital Sky Survey was like panning a riverbed, washing away silt and mud to uncover bits of gold".
Before Damjanov and her team had thought to look through the immense database of the SDSS, no one could find the elusive galaxies after their original discovery in 2005.
See also
List of galaxies
List of nearest galaxies
List of spiral galaxies
References
Galaxies | Red nugget | Astronomy | 645 |
19,192,569 | https://en.wikipedia.org/wiki/Comparison%20of%20online%20backup%20services | This is a comparison of online backup services.
Online backup is a special kind of online storage service; however, various products that are designed for file storage may not have features or characteristics that others designed for backup have. Online Backup usually requires a backup client program. A browser-only online storage service is usually not considered a valid online backup service.
Online folder sync services can be used for backup purposes. However, some Online Folder Sync services may not provide a safe Online Backup. If a file is accidentally locally corrupted or deleted, it depends on the versioning features of a Folder Sync service, whether this file will still be retrievable.
Comparison
Legend
Windows/Linux/Mac/iOS/Android/BlackBerry: Supported operating systems for thick client (native binary application), which provide background data transmission and setting services.
Zero knowledge: The service provider has no knowledge of the user's encryption key, ensuring privacy of the backup data.
Secure Key Management: If yes, the user holds and controls the encryption key. If no, the service provider holds and controls the encryption key.
Payment options/plans:
Limited MB plan: Pay per computer. Additional fee for storage over a threshold.
Unlimited MB plan: Pay per computer. Storage per computer is unlimited.
$/MB plan: Pay per unit of storage, but unlimited computers may share that storage.
Cloud hosted Net Drive: Cloud can serve storage over WebDAV, SMB/CIFS, NFS, AFP or other NAS protocol, allowing files to be streamed from the cloud. A change made to the cloud is immediately accessible to applications on all clients without needing to pre-download (sync) the file in full.
Sync: Synchronization between computers, and/or mobile devices (PDA, MDA,...)
Public Internet file hosting
Restore via physical media
Server location: Countries where physical servers are located. Where the data will be located.
Still in Beta version
Whether the desktop client (if available) can detect and upload changes without scanning all files.
Many backup services offer a limited free plan, often for personal use. Often it is possible to increase the free backup limit through coupons, referrals, or other means that are not included in this column. This column also does not include free trials that are only available for a limited period of time.
External hard drive support: Can refer to an alternate backup destination or whether the service can back up external drives.
Hybrid Online Backup works by storing data to local disk so that the backup can be captured at high speed, and then either the backup software or a D2D2C (Disk to Disk to Cloud) appliance encrypts and transmits data to a service provider. Recent backups are retained locally, to speed data recovery operations.
Unlimited BW: If bandwidth capping or limits are used on accounts.
Comments
Acronis Up to five PCs, always incremental backups, remote access from the web
Backblaze Data de-duplication; block-level incremental.
Barracuda Backup Service Data de-duplication; real-time hybrid on-site/off-site data back-up.
BullGuard Backup 5 PC/license, fast upload speeds, mobile access, encrypted transfer and storage, password-protected settings, free 24/7 support.
Carbonite Block-level incremental, Home or Pro editions. iPhone/ Blackberry/ Android App available to remotely access data from the online backup (For Pro: Users of the computer which are backed up, not available for the Administrator of the Pro). Can manually select files to upload that are larger than 4 GB.
Cloudberry Backup Image & File Based backups, data de-duplication, block-level and multiple cloud providers supported.
CloudJuncxion Decentralized multi-cloud backup with integrated sharing, sync, backup, and Cloud NAS. Fault-tolerance against failure of a constituent cloud.
Crashplan
Unlimited destinations. Data de-duplication; block-level incremental. Can run server-free, exchanging backup space with friends and family.
Datashield High-level encryption, personalized encryption key, shared cloud drive, sync folder functionality .
Dolly Drive
Cloud storage that is specifically designed for the Mac. Also allows users to store files exclusively in the cloud for seamless access on any computer or mobile device.
Diino iPhone/Android app available.
Dropbox Data de-duplication, delta sync, iPhone/Android/Blackberry app available.
Dropmysite website backup, database backup, SFTP support, free up to 2 GB.
Egnyte Delta sync, Google Docs sync, user and group management
ElephantDrive Auto-transfer from defunct Xdrive.
F-Secure [Steek acquired by F-Secure July 2009]
Humyo Humyo was acquired by Trend Micro and will become part of Trend Micro SafeSync. Humyo no longer accepts new clients.
IASO Backup Advanced data reduction technology. Data de-duplication mechanism. High level of scalability and cost effectiveness.
ICFiles Secure File Share Storage. Proprietary license download client. High level security, SOC 2 TYPE II, ISO 27001,27017, 27018, CSA, PCI, HIPAA, CJIS, EU Model Clauses, on request private servers for FISMA and FedRAMP.
IDrive Proprietary license download client. Automatic Selection. Continuous Data Protection. "Virtual drive" explorer.
Jungle Disk Proprietary license download client sample code.
KeepVault Real-time hybrid on-site and offsite data backup.
Memopal Cross-user de-duplication, delta sync.
MiMedia Initial seed via a MiMedia-owned external hard drive available (no extra cost, shipping included).
Mozy Data de-duplication; block-level incremental. "Mozy Data Shuttle" physical seeding service available for extra fee.
Replicalia Professional Backup for Professional Data.
SpiderOak Data de-duplication."Zero Knowledge" encryption.
StoreGrid Cloud Byte-level incremental backup, local backup, Disk Image backup—BMR and physical seeding.
Syncplicity Google Docs sync, Central Management with Business Console.
Tarsnap Client source available; data de-duplication; block-level incremental.
TeamDrive Store encrypted data on any WebDAV server; supports working offline; files can be commented; built-in support for conflict resolution.
Unitrends Vault2Cloud Data de-duplication; hybrid on- and off-premises data backup; physical seeding.
UpdateStar Online Backup Data de-duplication; block-level incremental.
Usenet backup Is the method of storing backup data on the usenet.
Windows Live Mesh Replaces windows live sync and windows live folder.
Zetta Enterprise-grade Online Backup Supports Linux, Mac OS, and Windows, high speed WAN optimization, SAS 70 certified data centers.
Zmanda Cloud Backup Available in German and Japanese languages, supports MS SQL Server, MS Exchange, SharePoint, MySQL Database, System State, Oracle.
Versioning
Any changes can be undone, and files can be undeleted.
Acronis Supports detailed history of changes to files with browsing by date or version number.
Backblaze Old versions of files are kept for 30 days by default; One-year or Forever Retention is optional.
Box Versioning is included in paid subscription
Carbonite Keeps old versions for up to three months. It keeps one version for each day of the past week, one version for each of the previous three weeks, and one version for each of the previous two months that the file has been backed up. Versioning available for PC computers only; not available for Mac.
CloudJuncxion Supports multiple versions less than a week old, one version less than two weeks old, one version less than month old, and one version older than a month.
Crashplan Options: All, or staged (daily, then weekly, etc.).
Cubby All previous versions and deleted files are kept until explicitly removed by the user or the user runs out of space. All deleted files and previous versions count towards the storage limit.
Dolly Drive Yes. Keeps unlimited versions of files.
Dropbox By default, Dropbox saves a history of all deleted and earlier versions of files for 30 days for all Dropbox accounts.
Dropmysite Provides incremental backups with the ability to download every snapshot.
ElephantDrive Any number of versions can be kept for any amount of time.
Google Drive Old versions of files are kept for 30 days or 100 revisions. Revisions can be set not to be automatically deleted.
IASO Backup All versions of files can be kept for different periods of time, starting from 1 month to 1 year or more.
ICFiles No files are kept after delete, auto delete clears at every 24 hours.
iDrive Up to 10 old versions of files are kept forever (until explicitly removed).
Mozy Old version of files are kept for 30 days. Pro 60 days, Enterprise 90 days.
PowerFolder Five versions are kept online. In the client it is configurable how many versions to store locally.
SOS Online Backup (Infrascale) All versions are kept. Only the largest counts towards the storage limit.
SpiderOak All versions are kept. All files can be undeleted.
SugarSync Five versions are kept. Only the most recent version of each of existing files as well as deleted files count towards the storage limit.
Sync.com Sync.com saves a history of all deleted and earlier versions of files, 30 days for free accounts, indefinitely for premium plans.
Syncplicity Old versions of files, as well as deleted files, are kept for 30 days. Configurable for business or enterprise-class services.
TeamDrive All previous versions are kept and can be restored.
Tresorit Versioning is included in paid subscription
Zetta Enterprise-grade Online Backup All versions are kept. All files can be undeleted.
Other features and limitations
Other notable limitations or features.
Baidu Cloud Must be registered by verified phone first.
Box Performance degrades after 10,000 files in sync folder. Technical limit of 40,000 files in sync folder. Does not sync .tmp files, Outlook PST files, hidden files (hidden folders are synced), or any file or folder with \/*?":<>| in the name.
CloudJuncxion Decentralized fragment-and-disperse storage across a collection of heterogeneous clouds for maximal security. Supports a Virtual Private Cloud model for complete control by the enterprise customer. Supports Sync Groups for greater control over synchronization of files across multiple devices.
Dropbox Performance degrades with more than 300,000 files in sync folder. This is a soft limit.
Google Drive All account types are limited to 750 GB upload bandwidth per day. Enterprise accounts are now limited to 5 TB per paid user on the account whereas prior to May 2023 only a single user was required for the advertised unlimited storage. Once 5 users are on an Enterprise account, more storage can be requested in 25 TB allotments once every 90 days, but extra storage is not guaranteed. The extra allotted storage is also removed when users on the account drop under 5. Thus unlimited storage is unfeasible to attain with Google Drive's new restrictions.
Sugarsync Limited to 80,000 files per top level sync folder. To work around, one can create multiple syncing folders, but each top level folder is limited to 80k files. Also, Microsoft outlook and Apple iTunes databases are unsupported.
Trustbox A 3-layer encrypted storage supports privacy for an unlimited file version retrieval. Restore any file from any point in time.
Defunct services
Bitcasa closed its services in February 2017.
Copy was discontinued on May 1, 2016
Dell DataSafe was discontinued on June 11, 2015.
drop.io
Mozy, shutdown in 2019, and it redirects users to Carbonite
Norton Zone was discontinued on July 7, 2014.
Streamload aka MediaMax
Ubuntu One was discontinued on June 1, 2014.
Windows Live Mesh
Wuala was discontinued on November 15, 2015.
Xdrive
ZumoDrive
See also
File hosting service
Remote backup service
Comparison of online music lockers
Comparison of file synchronization software
Comparison of file hosting services
Cloud storage
Shared resource
File sharing
List of backup software
References
File hosting
Hard disk software
Cloud storage
Online services comparisons
Online backup
Comparison of online backup services | Comparison of online backup services | Technology | 2,570 |
3,557,336 | https://en.wikipedia.org/wiki/Koiter%20Medal | The Warner T. Koiter Medal was established in 1996 by the American Society of Mechanical Engineers. It is awarded in recognition of distinguished work in the field of solid mechanics.
The award was funded by the Technical University of Delft in the honor of Warner T. Koiter, who was a professor at the university from 1949 till 1979. Koiter's most influential work dealt with the non-linear stability of structures.
The recipient is given an honorarium and a bronze medal.
Nomination procedure
The Koiter Medal Committee consists of the five recent Koiter Medalists, the five members of the executive committee of the ASME International Applied Mechanics Division (AMD), and the five recent past chairs of the AMD. Upon receiving recommendations from the international community of applied mechanics, the Committee nominates a single medalist every year. This nomination is subsequently approved by the ASME Committee on Honors.
Koiter Medal recipients
2024 – H. Jerry Qi
2023 – Yiu-Wing Mai
2022 – Vikram Deshpande
2021 – Gerhard A. Holzapfel, Graz University of Technology, Austria
2020 – Anthony Waas, University of Michigan
2019 – K. T. Ramesh, Johns Hopkins University
2018 – M. Taher A. Saif, University of Illinois
2017 – Wei Yang, Zhejiang University
2016 – Pedro Ponte Castañeda, University of Pennsylvania
2015 – Kaushik Bhattacharya, California Institute of Technology
2014 – G. Ravichandran, California Institute of Technology
2013 – Norman A. Fleck, Cambridge University
2012 – Erik van der Giessen, Rijksuniversiteit Groningen
2011 – James G. Simmonds
2010 – Nicolas Triantafyllidis
2009 – Stelios Kyriakides
2008 – Richard. D. James, University of Minnesota
2007 – Chin-Teh Sun
2006 – Pierre Suquet
2005 – Raymond W. Ogden
2004 – Zenon Mróz, Polish Academy of Sciences
2003 – David R. J. Owen
2002 – James K. Knowles, California Institute of Technology
2001 – Wolfgang G. Knauss, California Institute of Technology
2000 – Giulio Maier
1999 – Charles R. Steele
1998 – Viggo Tvergaard
1997 – Warner T. Koiter
References
Information for nomination
Koiter Medal page at the ASME website
See also
List of mechanical engineering awards
Applied Mechanics Division
American Society of Mechanical Engineers
Applied mechanics
Mechanician
Mechanical engineering awards | Koiter Medal | Engineering | 490 |
77,826,356 | https://en.wikipedia.org/wiki/Algebraic%20homotopy | In mathematics, algebraic homotopy is a research program on homotopy theory proposed by J.H.C. Whitehead in his 1950 ICM talk, where he described it as:
In spirit, the program is somehow similar to Grothendieck's homotopy hypothesis. However, according to Ronnie Brown, "Looking again at Esquisses d'un Progamme, it seems that programme has currently little relation to Whitehead's."
References
https://ncatlab.org/nlab/show/algebraic+homotopy
Handbook of Algebraic Topology edited by I.M. James
Further reading
https://ncatlab.org/nlab/show/Algebraic+Homotopy, an entry about a book
Homotopy theory
Homotopical algebra | Algebraic homotopy | Mathematics | 164 |
11,485,462 | https://en.wikipedia.org/wiki/Z18%20small%20nucleolar%20RNA | Z18 small nucleolar RNA (also known as SNORD74 and U74) is a non-coding RNA (ncRNA) molecule which functions in the modification of other small nuclear RNAs (snRNAs). This type of modifying RNA is usually located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis. It is known as a small nucleolar RNA (snoRNA) and also often referred to as a guide RNA.
Z18 snoRNA belongs to the C/D box class of snoRNAs which contain the conserved sequence motifs known as the C box (UGAUGA) and the D box (CUGA). Most of the members of the box C/D family function in directing site-specific 2'-O-methylation of substrate RNAs.
See also
Z6 small nucleolar RNA
Z12 small nucleolar RNA
Z30 small nucleolar RNA
References
External links
snoRNABase page for U74
Small nuclear RNA | Z18 small nucleolar RNA | Chemistry | 218 |
15,495,100 | https://en.wikipedia.org/wiki/Waveguide%20rotary%20joint | A waveguide rotary joint is used in microwave communications to connect two different types of RF waveguides. Because coaxial parts are symmetrical in ø direction, free rotation without performance degradation is accomplished. In the rotating part, electrical continuity is achieved by λ/4-chokes eliminating metal contacts. The Rotary Joints can have both waveguide ports at a right angle to the rotational axis, "U-style", one waveguide port at a right angle and one in line, "L-style" or both waveguide ports in line. "I-style". Waveguide Rotary Joint modules are available for all frequency bands. Common materials for waveguide rotary joints include aluminum, brass, bronze, copper, and silver.
References
Radio technology | Waveguide rotary joint | Technology,Engineering | 152 |
68,522,460 | https://en.wikipedia.org/wiki/Table%20extraction | Table extraction is the process of recognizing and separating a table from a large document, possibly also recognizing individual rows, columns or elements.
It may be regarded as a special form of information extraction.
Table extractions from webpages can take advantage of the special HTML elements that exist for tables, e.g., the "table" tag,
and programming libraries may implement table extraction from webpages.
The Python pandas software library can extract tables from HTML webpages via its read_html() function.
More challenging is table extraction from PDFs or scanned images, where there usually is no table-specific machine readable markup.
Systems that extract data from tables in scientific PDFs have been described.
Wikipedia presents some of its information in tables,
and, e.g., 3.5 million tables can be extracted from the English Wikipedia.
Some of the tables have a specific format, e.g., the so-called infoboxes.
Large-scale table extraction of Wikipedia infoboxes forms one of the sources for DBpedia.
Commercial web services for table extraction exist, e.g., Amazon Textract, Google's Document AI, IBM Watson Discovery, and Microsoft Form Recognizer.
Open source tools also exist, e.g., PDFFigures 2.0 that has been used in Semantic Scholar.
In a comparison published in 2017, the researchers found the proprietary program ABBYY FineReader to yield the best PDF table extraction performance among six different tools evaluated. In a 2023 benchmark evaluation, Adobe Extract, a cloud-based API that employs Adobe’s Sensei AI-platform, performed best among five tools evaluated for table extraction.
References
Natural language processing | Table extraction | Technology | 350 |
78,389,911 | https://en.wikipedia.org/wiki/NGC%201285 | NGC1285 is a barred spiral galaxy in the constellation of Eridanus. Its velocity with respect to the cosmic microwave background is 5081 ± 12km/s, which corresponds to a Hubble distance of . However, three non-redshift measurements give a distance of . It was discovered by Heinrich Louis d'Arrest on 28 October 1865.
Supernovae
Three supernovae have been observed in NGC 1285:
SN 2004F (typeIIn-pec, mag. 17.8) was discovered by the Lick Observatory Supernova Survey on 16 January 2004.
SN 2013el (typeIb-pec, mag. 15.5) was discovered by Stu Parker on 11 July 2013.
SN 2017fvf (typeIIP, mag. 17.81) was discovered by the Gaia Photometric Science Alerts programme on 30 July 2017.
See also
List of NGC objects (1001–2000)
References
External links
1285
012259
-01-09-026
03154-0728
Eridanus (constellation)
18651028
Discoveries by Heinrich Louis d'Arrest
barred spiral galaxies | NGC 1285 | Astronomy | 234 |
1,387,878 | https://en.wikipedia.org/wiki/Dustpan | A dustpan, the small version of which is also known as a "hearth brush and shovel” (from its use of cleaning the fireplace hearth), is a cleaning utensil. The dustpan is commonly used in combination with a broom or long brush. The small dustpan may appear to be a type of flat scoop. Though often hand-held for home use, industrial and commercial enterprises use a hinged variety on the end of a stick to allow the user to stand instead of stoop while using it.
Handheld dustpans may be used with either a full-size broom or with a smaller broom or a brush. This second combination may be sold as one unit. A variant on the dustpan is the silent butler, a handheld, lidded dustpan.
Materials and Design
Dustpans typically features a flat, angled surface for ease of debris collection, with raised sides to contain the swept materials. They are manufactured from various materials including plastic, metal, and composite materials. The different materials affect durability, weight, and price. Modern dustpans may incorporate features such as rubber edges to improve debris collection efficiency, ergonomic handles for user comfort, and integrated brushes or brooms for convenience. There is a growing trend towards producing dustpans from recycled or eco-friendly materials to reduce environmental impact. These sustainable materials include bamboo, wood, aluminum, and recycled plastics.
Small Dustpans are typically used for light, everyday cleaning tasks. Dimensions may range from 20 cm to 30 cm in width, with a capacity sufficient for small amounts of debris. Large and industrial dustpans are designed for heavy-duty use, with widths exceeding 30 cm and larger capacities to handle more significant volumes of debris.
History
In 1858, the first patent for a dustpan was given to T.E. McNeill. This design featured a flat scoop with a handle, which could be held in one hand while sweeping with the other. This basic design laid the foundation for modern dustpans.
In 1897, Lloyd P. Ray, an African American inventor, patented an improved dustpan with a more ergonomic handle and a raised edge to prevent debris from spilling out. This design was influential in shaping the dustpans we use today.
Gallery
References
Cleaning tools
Mechanical hand tools | Dustpan | Physics | 466 |
17,774,270 | https://en.wikipedia.org/wiki/Zhumir | Zhumir Latin Spirit is an Ecuadorian brand of spirits, marketed on a national and international scale. Zhumir is often, incorrectly, referred to as Rum outside of Ecuador.
Origins
Zhumir was originally founded by Don Eduardo Crespo Malo. The term "Zhumir" was coined in 1870 by Francesco Cabeza de Vaca to describe spirits, and the distillery has roots in Cuenca, where it was founded in 1966 by Doña Hortensia Mata Ordóñez as "Destilería La Playa." The name was changed in 1982 to "Destilería Zhumir C. Ltda" in order to more closely identify the company with its most popular product.
When Zhumir began, it was a cottage industry, bottling and selling spirits made in the traditional artesanal manner, however the product quickly became so popular that the company installed an industrial distillery to keep up with demand. Much of the sugarcane used to produce Zhumir is grown in company owned fields in the valley of Paute in the province of Azuay, and the corporation has its headquarters in the Azuay capital, Cuenca.
Flavours
Zhumir's Neat Spirits
Zhumir Blender - triple-filtered, dry, flavourless spirit, 68 proof.
Zhumir Watermelon - semi-dry, Watermelon and Strawberry flavoured spirit, (Extremely popular among youngsters) 15 proof .
Zhumir Coco - semi-dry, coconut flavoured spirit, 42 proof.
Zhumir Maracuyá - semi-dry, passionfruit flavoured spirit, 42 proof.
Zhumir Durazno - semi-dry, peach flavoured spirit, 42 proof.
Zhumir Limón - semi-dry, lime flavoured spirit, 60 proof.
Zhumir Reposado - a fine, aged spirit similar to amber rum, 80 proof.
Zhumir Reserva Especial - a fine, aged spirit similar to dark rum, 80 proof.
"Zhumir Naranjilla"
As well, the company offers blended spirit-based liqueurs
Piña Colada with Zhumir - a pre-mixed Pina Colada, 30 proof.
Tacao with Zhumir - a chocolate cream liqueur, 30 proof.
Rompope with Zhumir - a cinnamon and egg cream liqueur of flavour similar to eggnog, 32 proof.
External links
Official website
References
Distilled drinks
Companies of Ecuador
Ecuadorian brands
Alcoholic drink brands
Sugar-based alcoholic drinks
Food and drink in Ecuador | Zhumir | Chemistry | 508 |
1,462,457 | https://en.wikipedia.org/wiki/Local%20property | In mathematics, a mathematical object is said to satisfy a property locally, if the property is satisfied on some limited, immediate portions of the object (e.g., on some sufficiently small or arbitrarily small neighborhoods of points).
Properties of a point on a function
Perhaps the best-known example of the idea of locality lies in the concept of local minimum (or local maximum), which is a point in a function whose functional value is the smallest (resp., largest) within an immediate neighborhood of points. This is to be contrasted with the idea of global minimum (or global maximum), which corresponds to the minimum (resp., maximum) of the function across its entire domain.
Properties of a single space
A topological space is sometimes said to exhibit a property locally, if the property is exhibited "near" each point in one of the following ways:
Each point has a neighborhood exhibiting the property;
Each point has a neighborhood base of sets exhibiting the property.
Here, note that condition (2) is for the most part stronger than condition (1), and that extra caution should be taken to distinguish between the two. For example, some variation in the definition of locally compact can arise as a result of the different choices of these conditions.
Examples
Locally compact topological spaces
Locally connected and Locally path-connected topological spaces
Locally Hausdorff, Locally regular, Locally normal etc...
Locally metrizable
Properties of a pair of spaces
Given some notion of equivalence (e.g., homeomorphism, diffeomorphism, isometry) between topological spaces, two spaces are said to be locally equivalent if every point of the first space has a neighborhood which is equivalent to a neighborhood of the second space.
For instance, the circle and the line are very different objects. One cannot stretch the circle to look like the line, nor compress the line to fit on the circle without gaps or overlaps. However, a small piece of the circle can be stretched and flattened out to look like a small piece of the line. For this reason, one may say that the circle and the line are locally equivalent.
Similarly, the sphere and the plane are locally equivalent. A small enough observer standing on the surface of a sphere (e.g., a person and the Earth) would find it indistinguishable from a plane.
Properties of infinite groups
For an infinite group, a "small neighborhood" is taken to be a finitely generated subgroup. An infinite group is said to be locally P if every finitely generated subgroup is P. For instance, a group is locally finite if every finitely generated subgroup is finite, and a group is locally soluble if every finitely generated subgroup is soluble.
Properties of finite groups
For finite groups, a "small neighborhood" is taken to be a subgroup defined in terms of a prime number p, usually the local subgroups, the normalizers of the nontrivial p-subgroups. In which case, a property is said to be local if it can be detected from the local subgroups. Global and local properties formed a significant portion of the early work on the classification of finite simple groups, which was carried out during the 1960s.
Properties of commutative rings
For commutative rings, ideas of algebraic geometry make it natural to take a "small neighborhood" of a ring to be the localization at a prime ideal. In which case, a property is said to be local if it can be detected from the local rings. For instance, being a flat module over a commutative ring is a local property, but being a free module is not. For more, see Localization of a module.
See also
Local path connectedness
Local-global principle
References
General topology
Homeomorphisms | Local property | Mathematics | 768 |
67,640,476 | https://en.wikipedia.org/wiki/Aureoumbra | Aureoumbra is a genus of algae belonging to the family Sarcinochrysidaceae.
Species:
Aureoumbra geitleri
Aureoumbra lagunensis
References
Ochrophyta
Ochrophyte genera | Aureoumbra | Biology | 49 |
65,978,396 | https://en.wikipedia.org/wiki/Reporter%20virus%20particles | Reporter virus particles (RVPs) are replication-incompetent virus particles engineered to express one or more reporter genes upon infecting susceptible cells. Since the RVP genome lacks genes essential for viral replication, RVPs are capable of only a single round of infection. Thus they are safe to work with under BSL-2 conditions, enabling the study of highly pathogenic viruses using standard laboratory facilities. Expression of a reporter such as luciferase can provide a quantitative readout of infection. With proper design and quality control, RVPs remain stable under common assay conditions and yield reproducible results that correlate with those obtained from live virus. These qualities make RVPs a safer and faster alternative to plaque assays, and especially well-suited for high-throughput applications. RVPs offer flexibility for different uses, as they are antigenically identical to wild-type virus, and can be engineered with various proteins or express mutant envelopes to study infectivity or antigenicity.
Applications
RVPs are most commonly used in neutralization assays, which measure the ability of serum or antibodies to prevent virus infectivity in vitro, with applications in vaccine development, antibody discovery, and serological testing. A related assay tests for antibody-dependent enhancement (ADE), a phenomenon where non-neutralizing antibodies against viruses can increase infectivity through their binding to the cellular Fc receptor, aiding entry of the virus into host cells.
Structure
Depending on the virus of interest and the desired application, RVPs can be pseudotypes, containing a heterologous self-assembling core (typically of lentiviral origin), as well as native envelope proteins corresponding to the studied virus. This type of RVP facilitates exceptional reliability and reproducibility of neutralization assay results, while maintaining antigenicity and safety. Alternatively, for structurally complex viruses such dengue and Zika viruses, RVPs are engineered to be antigenically identical to wild-type virus, using all of the structural proteins of the native virus.
Limitations
RVP production requires optimization of several elements, such as expression constructs, cell lines, and processing steps, to reach a yield sufficient for downstream applications and reproducibility across production lots. Although ideal for studying the effects of the immune response on virus entry, RVPs are replication-incompetent, and therefore typically do not allow study of the later stages of the viral life cycle. RVPs formed by pseudotyping contain the native form of the viral Envelope (or Spike) protein, but may not contain other structural elements from the original virus. Results obtained with RVPs are often compared to those obtained with live virus.
References
Virology
Viruses | Reporter virus particles | Biology | 551 |
25,181,777 | https://en.wikipedia.org/wiki/HD%20103197 | HD 103197 is a star with a planetary companion in the southern constellation of Centaurus. It has an apparent visual magnitude of 9.40, which is too faint to be viewed with the naked eye. Based on parallax measurements, HD 103197 is located at a distance of 187 light years from the Sun. It is drifting closer with a radial velocity of −4.6 km/s.
This is a K-type main-sequence star with a stellar classification of K1V(p). In 1978, N. Houk noted that the cores of the star's H and K lines are weakly in emission; hence the 'p' code indicating a spectral peculiarity. The star is an estimated five billion years old with a projected rotational velocity of approximately 0.6 km/s and it appears to be very inactive. It has 90% of the mass and 95% of the radius of the Sun. Its metal content is five-eighths greater than in the Sun.
In 2009, a gas giant exoplanet companion was discovered using the radial velocity method. This object is orbiting the host star at a distance of and a period of , with what is assumed to be a circular orbit.
See also
List of extrasolar planets
References
K-type main-sequence stars
Planetary systems with one confirmed planet
Centaurus
CD-49 06573
103197
057931 | HD 103197 | Astronomy | 286 |
48,768,665 | https://en.wikipedia.org/wiki/Non-malleable%20code | The notion of non-malleable codes was introduced in 2009 by Dziembowski, Pietrzak, and Wichs, for relaxing the notion of error-correction and error-detection. Informally, a code is non-malleable if the message contained in a modified code-word is either the original message, or a completely unrelated value. Non-malleable codes provide a useful and meaningful security guarantee in situations where traditional error-correction and error-detection is impossible; for example, when the attacker can completely overwrite the encoded message. Although such codes do not exist if the family of "tampering functions" F is completely unrestricted, they are known to exist for many broad tampering families F.
Background
Tampering experiment
To know the operation schema of non-malleable code, we have to have a knowledge of the basic experiment it based on. The following is the three step method of tampering experiment.
A source message is encoded via a (possibly randomized) procedure , yielding a code-word = .
The code-word is modified under some tampering-function to an erroneous-code-word =.
The erroneous-code-word is decoded using a procedure , resulting in a decoded-message = .
The tampering experiment can be used to model several interesting real-world settings, such as data transmitted over a noisy channel, or adversarial tampering of data stored in the memory of a physical device. Having this experimental base, we would like to build special encoding/decoding procedures , which give us some meaningful guarantees about the results of the above tampering experiment, for large and interesting families of tampering functions. The following are several possibilities for the type of guarantees that we may hope for.
Error correction
One very natural guarantee, called error-correction, would be to require that for any tampering function and any source-message s, the tampering experiment always produces the correct decoded message .
Error detection
A weaker guarantee, called error-detection, requires that the tampering-experiment always results in either the correct value or a special symbol indicating that tampering has been detected. This notion of error-detection is a weaker guarantee than error-correction, and achievable for larger F of tampering functions.
Algorithm description
A non-malleable code ensures that either the tampering experiment results in a correct decoded-message , or the decoded-message is completely independent of and unrelated to the source-message . In other word, the notion of non-malleability for codes is similar, in spirit, to notions of non-malleability for cryptographic primitives (such as encryption2, commitments and zero-knowledge proofs), introduced by the seminal work of Dolev, Dwork and Naor.
Compared to error correction or error detection, the "right" formalization of non-malleable codes is somewhat harder to define. Let be a random variable for the value of the decoded-message, which results when we run the tampering experiment with source-message and tampering-function , over the randomness of the encoding procedure. Intuitively, we wish to say that the distribution of is independent of the encoded message . Of course, we also want to allow for the case where the tampering experiment results in (for example, if the tampering function is identity), which clearly depends on .
Thus, we require that for every tampering-function , there exists a distribution which outputs either concrete values or a special same symbol, and faithfully models the distribution of for all in the following sense: for every source message , the distributions of and are statistically close when the symbol is interpreted as . That is, correctly simulates the "outcome" of the tampering-experiment with a function without knowing the source-messages , but it is allowed some ambiguity by outputting a same symbol to indicate that the decoded-message should be the same as the source-message, without specifying what the exact value is. The fact that depends on only and not on , shows that the outcome of is independent of , exempting equality.
Relation to error correction/detection
Notice that non-malleability is a weaker guarantee than error correction/detection; the latter ensure that any change in the code-word can be corrected or at least detected by the decoding procedure, whereas the former does allow the message to be modified, but only to an unrelated value. However, when studying error correction/detection we usually restrict ourselves to limited forms of tampering which preserve some notion of distance (e.g., usually hamming distance) between the original and tampered code-word.
For example, it is already impossible to achieve error correction/detection for the simple family of functions which, for every constant , includes a "constant" function that maps all inputs to . There is always some function in that maps everything to a valid code-word . In contrast, it is trivial to construct codes that are non-malleable w.r.t , as the output of a constant function is clearly independent of its input. The prior works on non-malleable codes show that one can construct non-malleable codes for highly complex tampering function families for which error correction/detection can not be achievable.
Application over tampering functions
Bit-wise independent tampering
As one very concrete example, we study non-malleability with respect to the family of functions which specify, for each bit of the code-word , whether to keep it as is, flip it, set it to 0, set it to 1. That is, each bit of the code-word is modified arbitrarily but independently of the value of the other bits of the code-word. We call this the “bit-wise independent tampering” family . Note that this family contains constant functions and constant-error functions as subsets. Therefore, as we have mentioned, error-correction and error-detection cannot be achieved w.r.t. this family. Nevertheless, the following can show an efficient non-malleable code for this powerful family.
With we denote the family which contains all tampering functions that tamper every bit independently. Formally, this family contains all functions that are defined by n functions (for i=1...n) as . Note that there are only 4 possible choices for each (i.e. how to modify a particular bit) and we name these “set to 0”, “set to 1”, “flip”, “keep” where the meanings should be intuitive. We call the above family the bit-wise independent tampering family.
All families of bounded size
Probabilistic Method Approach
For any "small enough" function family , there exists a (possibly inefficient) coding scheme which is non-malleable w.r.t. F. Moreover, for a fixed "small enough" function family , a random coding scheme is likely to be non-malleable w.r.t. F with overwhelming probability. Unfortunately, random coding schemes cannot be efficiently represented, nor is the encoding/decoding function likely to be efficient. Therefore, this result should merely be thought of as showing "possibility" and providing a target that we should then strive to match constructively. Moreover, this result also highlights the difference between "error-correction/detection" and "non-malleability" since a result of this form could not be true for the former notions.
Random Oracle Model Approach
It is not clear what the bound from the theorem of this type actually implies. For example, it does tell us that non-malleable codes exist with respect to all efficient functions, but this is misleading as we know that efficient non-malleable codes (and ultimately we are only interested in such) cannot be non-malleable w.r.t. this class. Nevertheless, the result by the probabilistic method does give us codes which are non-malleable w.r.t. very general classes of functions in the random oracle model.
Model of tamper-resilient security
In this model, we consider two ways of interacting with the system:
Execute(): A user can provide the system with Execute(x) queries, for , in which case the system computes , updates the state of the system to and outputs .
Tamper(): We also consider tampering attacks against the system, modeled by Tamper() commands, for functions . Upon receiving such command, the system state is set to .
An attacker that can also interact with the system via Tamper queries can potentially learn significantly more about the secret state, even recover it entirely. Therefore, we would like to have a general method for securing systems against tampering attacks, so that the ability to issue Tamper queries (at least for functions f in some large family ) cannot provide the attacker with additional information. By using non-malleable code for this purpose we have the conclusion: Let be any coding scheme which is non-malleable w.r.t , then can also be tamper-simulate w.r.t. .
Capacity of non-malleable codes
For every family with , there exist non-malleable codes against with rate arbitrarily close to 1 − (this is achieved w.h.p. by a randomized construction).
For families of size against which there is no non-malleable code of rate 1 − (in fact this is the case w.h.p for a random family of this size).
1 − is the best achievable rate for the family of functions which are only allowed to tamper the first bits of the code-word, which is of special interest.
References
Algorithms | Non-malleable code | Mathematics | 2,046 |
2,212,081 | https://en.wikipedia.org/wiki/Inspissation | Inspissation is the process of increasing the viscosity of a fluid, or even of causing it to solidify, typically by dehydration or otherwise reducing its content of solvents. The term also has been applied to coagulation by heating of some substances such as albumens, or cooling some such as solutions of gelatin or agar. Some forms of inspissation may be reversed by re-introducing solvent, such as by adding water to molasses or gum arabic; in other forms, its resistance to flow may include cross-linking or mutual adhesion of its component particles or molecules, in ways that prevent their dissolving again, such as in the irreversible setting or gelling of some kinds of rubber latex, egg-white, adhesives, or coagulation of blood.
Intentional use
Inspissation is the process used when heating high-protein containing media; for example to enable recovery of bacteria for testing. Once inspissation has occurred, any stained bacteria, such as Mycobacteria, can then be isolated.
A serum inspissation or fractional sterilization is a process of heating an article on 3 successive days as follows:
Pathologic inspissation
In cystic fibrosis, inspissation of secretions in the respiratory and gastrointestinal tracts is a major mechanism causing the disease.
References
Further reading
Textbook of Microbiology by Prof. C P Baveja,
Textbook of Microbiology by Ananthanarayan and Panikar,
Microbiology
Zoology | Inspissation | Chemistry,Biology | 318 |
67,573,786 | https://en.wikipedia.org/wiki/Podman | In computing, Podman (pod manager) is an open source Open Container Initiative (OCI)-compliant container management tool from Red Hat used for handling containers, images, volumes, and pods on the Linux operating system, with support for macOS and Microsoft Windows via a virtual machine. Based on the libpod library, it offers APIs for the lifecycle management of containers, pods, images, and volumes. The API is identical to the Docker API. Podman Desktop provides an alternative to Docker Desktop.
Security
Podman lets containers run without root privileges (rootless), meaning they can be created, run, and managed by regular users without administrator rights.
See also
List of Linux containers
References
Further reading
Containerization software
Software using the Apache license | Podman | Technology | 156 |
17,595,351 | https://en.wikipedia.org/wiki/HD%2045652 | HD 45652 is a star with an exoplanetary companion in the equatorial constellation of Monoceros. It was officially named Lusitânia on 17 December 2019, after the IAU100 press conference in Paris by the IAU (International Astronomical Union). This star has an apparent visual magnitude of 8.10, making it an 8th magnitude star that is too dim to be visible to the naked eye. The system is located at a distance of 114 light-years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −5 km/s. It shows a high proper motion, traversing the celestial sphere at an angular rate of .
The measured atmospheric properties match a metal-rich late G- or early K-type dwarf star. It is a middle-aged main sequence star, about five billion years old, and is chromospherically inactive. The star is smaller and less massive than the Sun. It is radiating 61% of the Sun's luminosity from its photosphere at an effective temperature of 5,342 K. HD 45652 is spinning with a projected rotational velocity of 3.5 km/s.
Planetary system
In May 2008, the discovery of an extrasolar planet, HD 45652 b, orbiting the star was announced. The planet was detected by the radial velocity method, using observations made from 2005 to 2007. It has been assigned the name Viriato by the IAU Division C Working Group on Star Names.
References
External links
G-type main-sequence stars
K-type main-sequence stars
Planetary systems with one confirmed planet
Monoceros
Durchmusterung objects
045652
030905 | HD 45652 | Astronomy | 349 |
54,755,318 | https://en.wikipedia.org/wiki/Hydrogenobacter | Hydrogenobacter is a genus of bacteria, one of the few in the phylum Aquificota. Type species is H. thermophilus. This genus belongs to Bacteria as opposed to the other inhabitants of extreme environments, the Archaea.
Phylogeny
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI)
See also
List of bacterial orders
List of bacteria genera
References
Bacteria genera
Aquificota
Thermophiles | Hydrogenobacter | Biology | 118 |
26,738,921 | https://en.wikipedia.org/wiki/Phallus%20pygmaeus | Phallus pygmaeus is a species of stinkhorn mushroom. It was found growing on rotten wood in the State of Pernambuco, Brazil, and first reported in 2003. The fruiting bodies, which are otherwise similar in appearance to the well-known Phallus impudicus, do not typically grow more than long.
References
External links
Phallales
Fungus species | Phallus pygmaeus | Biology | 81 |
60,456,582 | https://en.wikipedia.org/wiki/Evolution%20of%20bacteria | The evolution of bacteria has progressed over billions of years since the Precambrian time with their first major divergence from the archaeal/eukaryotic lineage roughly 3.2-3.5 billion years ago. This was discovered through gene sequencing of bacterial nucleoids to reconstruct their phylogeny. Furthermore, evidence of permineralized microfossils of early prokaryotes was also discovered in the Australian Apex Chert rocks, dating back roughly 3.5 billion years ago during the time period known as the Precambrian time. This suggests that an organism in of the phylum Thermotogota (formerly Thermotogae) was the most recent common ancestor of modern bacteria.
Further chemical and isotopic analysis of ancient rock reveals that by the Siderian period, roughly 2.45 billion years ago, oxygen had appeared. This indicates that oceanic, photosynthetic cyanobacteria evolved during this period because they were the first microbes to produce oxygen as a byproduct of their metabolic process. Therefore, this phylum was thought to have been predominant roughly 2.3 billion years ago. However, some scientists argue they could have lived as early as 2.7 billion years ago, as this was roughly before the time of the Great Oxygenation Event, meaning oxygen levels had time to increase in the atmosphere before it altered the ecosystem during this event.
The rise in atmospheric oxygen led to the evolution of Pseudomonadota (formerly proteobacteria). Today this phylum includes many nitrogen fixing bacteria, pathogens, and free-living microorganisms. This phylum evolved approximately 1.5 billion years ago during the Paleoproterozoic era.
However, there are still many conflicting theories surrounding the origins of bacteria. Even though microfossils of ancient bacteria have been discovered, some scientists argue that the lack of identifiable morphology in these fossils means they can not be utilised to draw conclusions on an accurate evolutionary timeline of bacteria. Nevertheless, more recent technological developments means more evidence has been discovered.
Defining bacteria
Bacteria are prokaryotic microorganisms that can either have a bacilli, spirilli, or cocci shape and measure between 0.5-20 micrometers. They were one of the first living cells to evolve and have spread to inhabit a variety of different habitats including hydrothermal vents, glacial rocks, and other organisms. They share characteristics with eukaryotic cells including the cytoplasm, cell membrane, and ribosomes. Some unique bacterial features include the cell wall (also found in plants and fungi), flagella (not common for all bacteria), and the nucleoid.
Bacteria can metabolise in different ways, most commonly by heterotrophic or autotrophic (either photosynthetic or chemosynthetic) processes. Bacteria reproduce through binary fission, though they can still share genetic information between individuals either by transduction, transformation, or conjugation.
Process of bacterial evolution
Bacteria evolve in a similar process to other organisms. This is through the process of natural selection, whereby beneficial adaptations are passed onto future generations until the trait becomes common within the entire population. However, since bacteria reproduce via binary fission—a form of asexual reproduction—the daughter cell and parent cell are genetically identical. This makes bacteria susceptible to environmental pressures, an issue that is overcome by sharing genetic information via transduction, transformation, or conjugation. This allows for new genetic and physical adaptations to develop, allowing bacteria to adapt to their environment and evolve. Furthermore, bacteria can reproduce in as little as 20 minutes, which allows for fast adaptation, meaning new strains of bacteria can evolve quickly. This has become an issue regarding antibiotic resistant bacteria.
Thermotogales
Thermotogota bacteria are typically thermophilic or hyperthermophilic, gram-negative staining, anaerobic organisms that can live near hydrothermal vents where temperatures can range between 55-95 °C. They are thought to be some of the earliest forms of life. Evidence of bacteria has been discovered in the Australian Apex Chert near ancient hydrothermal vents. These rocks date back 3.46 billion years and, because oxygen was not present in large quantities in Earth's early atmosphere, these fossils are thought to represent early thermophilic bacteria, which do not require oxygen to survive. Furthermore, living species such as Thermotoga neapolitana, which are thought to resemble their ancestral form, live around these vents, which some scientists have used as evidence to support this theory.
More recent evidence suggests that Thermotogales evolved roughly between 3.2-3.5 billion years ago. This evidence was collected via gene sequencing of bacterial nucleoids to reconstruct their phylogeny. The first major divergence within the Thermotogales phylum was between Thermotogaceae and Fervidobacteriaceae, however, it is yet to be determined as to when this occurred. The family of Thermotogaceae then diverged into the genus Thermotoga and the genus Pseudothermotoga. The genus Thermotoga represents the majority of existing hyperthermophiles and are unique in that they are wrapped in an outer membrane that is referred to as a "toga". Some extant Thermotoga species include T. neapolitana.
Thermotogale phylogeny
The phylogeny based on the work of the All-Species Living Tree Project.
Cyanobacteria
Cyanobacteria or blue green-algae is a gram negative bacteria, a phylum of photosynthetic bacteria that evolved between 2.3-2.7 billion years ago. This prokaryote produces oxygen as a byproduct of its photosynthetic processes. They have made a distinctive impact in pharmaceutical and agricultural industry due to their potential of making bioactive compounds with antibacterial, anti-fungal, antiviral, and anti-algal properties. Typically they form motile filaments referred to as hormogonia, which can form colonies and then bud and travel to colonise new areas. They have been located in environments including freshwater, oceans, soil and rock (both damp and dry), as well as arctic rock.
These organisms had evolved photosynthetic reaction centres and became the first oxygen producing autotrophs to appear in the fossil record. They utilise sunlight in order to drive their metabolic processes, which removes carbon dioxide from the atmosphere and releases oxygen. Due to this trait some scientist credit this phylum to causing the Great Oxygenation Event roughly 2.3 billion years ago
However, the closest known relatives of oxygen producing Cyanobacteria did not produce oxygen. These relatives are Melainabacteria and Sericytochromatia, neither of which can photosynthesise. Through genetic sequencing, scientists discovered that these two groups did not have any remnants of the genes required for the functioning of photosynthetic reactions. This suggests that Cyanobacteria, Melainabacteria, and Sericytochromatia evolved from a non-photosynthetic common ancestor.
References
Further reading
External links
What are Cyanobacteria and What are its Types?
Webserver for Cyanobacteria Research
Evolutionary biology | Evolution of bacteria | Biology | 1,529 |
36,960,939 | https://en.wikipedia.org/wiki/HD%20165189%20and%20HD%20165190 | HD 165189 and HD 165190 are components of a visual binary star system located 143 light years away in the southern constellation of Corona Australis. It is visible to the naked eye with the primary having an apparent visual magnitude of . The system is a member of the Beta Pictoris Moving Group.
The pair orbit each other with a period of 450 years and a large eccentricity of 0.650. They have a projected separation of . Both components are A-type main-sequence stars; the primary has a stellar classification of A6 V while the secondary is A7 V. They have similar masses of 1.59 and 1.58 times the mass of the Sun, respectively.
References
A-type main-sequence stars
Beta Pictoris moving group
Corona Australis
Durchmusterung objects
088726
165189
Binary stars
Coronae Australis, 1 | HD 165189 and HD 165190 | Astronomy | 182 |
697,416 | https://en.wikipedia.org/wiki/Talk.origins | talk.origins (often capitalised to Talk.Origins or abbreviated as t.o.) is a Usenet discussion forum concerning the origins of life, and evolution. Its official purpose is to draw such debates out of the science newsgroups, such as sci.bio.evolution and sci.bio.paleontology. With the general decline of evolution/creationism debate and discontinuation of Google Groups support for Usenet in February 2024, Talk.Origins is now largely defunct.
History
The first post to talk.origins was a starter post by Mark Horton, dated 5 September 1986.
In the early 1990s, a number of FAQs on various topics were being periodically posted to the newsgroup. In 1994, Brett J. Vickers established an anonymous FTP site to host the collected FAQs of the newsgroup. In 1995, Vickers started the TalkOrigins Archive web site as another means of hosting the talk.origins FAQs. It maintains an extensive FAQ on topics in evolutionary biology, geology and astronomy, with the aim of representing the views of mainstream science. It has spawned other websites, notably TalkDesign "a response to the intelligent design movement", Evowiki, and the Panda's Thumb weblog.
The group was originally created as the unmoderated newsgroup net.origins as a 'dumping ground' for all the various flame threads 'polluting' other newsgroups, then renamed to talk.origins as part of the Great Renaming. Subsequently, after discussion on the newsgroup, the group was voted to be moderated in 1997 by the normal USENET RFD/CFV process, in which only spam and excessive crossposting are censored. The moderator for the newsgroup is David Iain Greig (and technically Jim Lippard as alternate/backup).
Culture
The group is characterized by a long list of in-crowd jokes like the fictitious University of Ediacara, the equally fictitious Evil Atheist Conspiracy which allegedly hides all the evidence supporting Creationism, a monthly election of the Chez Watt-award for "statements that make you go 'say what', or some such", pun cascades, a strong predisposition to quoting Monty Python, and a habit of calling penguins "the best birds".
Apart from the humor, the group includes rebuttals to creationist claims. There is an expectation that any claim is to be backed up by actual evidence, preferably in the form of a peer-reviewed publication in a reputable journal. The group as a whole votes for a PoTM-award (Post of The Month), which makes it into the annals of TalkOrigins Archive.
See also
National Center for Science Education (NCSE)
TalkOrigins Archive
References
External links
(Archive)
Newsgroups
Evolutionary biology | Talk.origins | Biology | 577 |
2,420,839 | https://en.wikipedia.org/wiki/Ice%20pack | An ice pack or gel pack is a portable bag filled with water, refrigerant gel, or liquid, meant to provide cooling. They can be divided into the reusable type, which works as a thermal mass and requires freezing, or the instant type, which cools itself down using chemicals but can only be used once. The instant type is generally limited to medical use as a cold compress to alleviate the pain of minor injuries, while the reusable type is both used as a cold compress and to keep food cool in portable coolers or in insulated shipping containers to keep products cool during transport.
Reusable packs
To be prepared for use, the pack is first placed in a freezer. Both ice and other non-toxic refrigerants (mostly water) can absorb a considerable amount of heat before they warm above .`
Ice packs are used in coolers to keep perishable foods (especially meats, dairy products, eggs, etc.) below the danger zone when outside a refrigerator or freezer, and to keep drinks pleasantly cool. The amount of ice needed varies with the amount of food, its initial temperature, the thermal insulation of the cooler, and the ambient temperature and exposure to direct sunlight. Ice initially well below freezing temperature will last a little longer.
Water has a much higher latent heat of fusion than most substances, and a melting temperature which is convenient and easily attained with, for example, a household freezer. Additives to improve the properties of water are often used. For example, substances can be added to prevent bacterial growth in the pack, or to prevent the water from solidifying so it remains a thick gel throughout use.
Gel packs are often made of non-toxic materials that will remain a slow-flowing gel, and therefore will not spill easily or cause contamination if the container breaks. Gel packs may be made by adding hydroxyethyl cellulose, sodium polyacrylate, superabsorbent polymer or vinyl-coated silica gel.
Hot-or-cold packs
Hot-or-cold packs are ice packs that are rated for high temperature use. They can be used as a normal reusable ice pack by storing in a freezer, but they can also be heated in water or a microwave oven to reach the desired temperature. The first hot and cold pack was introduced in 1948 with the name Hot-R-Cold-Pak and could be chilled in a refrigerator or heated in hot water. The first reusable hot cold pack that could be heated in boiling water or a microwave oven was first patented in 1973.
Instant ice packs
An instant cold pack is a single-use device that consists of two bags; one containing water, inside a bag containing ammonium nitrate, calcium ammonium nitrate or urea. When the inner bag of water is broken by squeezing the package, it dissolves the solid in an endothermic process. This process absorbs heat from the surroundings, quickly lowering the pack's temperature.
Instant cold packs are a convenient replacement for crushed ice used as first aid on sport injuries or heat illness, and can be carried as first aid to remote or wilderness areas where ice is unavailable. However, they do not provide as much or as long-lasting cooling as ice.
Safety concerns
Gel packs have been made with diethylene glycol and ethylene glycol. Both can cause illness if ingested in large amounts, making them unsuitable for use with food. The US Consumer Product Safety Commission recalled such packs.
See also
Cryotherapy
Hot pack
Hand warmer
Hilotherapy
Phase-change material
Enthalpy of fusion
References
Medical treatments
Cooling technology
Food preservation
Medical equipment
Cryotherapy
Packaging | Ice pack | Biology | 756 |
51,092,574 | https://en.wikipedia.org/wiki/Nandrolone%20cyclotate | Nandrolone cyclotate () (developmental code name RS-3268R), or nandrolone ciclotate, also known as 19-nortestosterone 17β-ciclotate, is a synthetic and injected anabolic–androgenic steroid (AAS) of the nandrolone (19-nortestosterone) group which was never marketed. It is an androgen ester – specifically, the C17β ciclotate (4-methylbicyclo[2.2.2]oct-2-ene-1-carboxylate) ester of nandrolone. Nandrolone cyclotate has potent and prolonged activity as an AAS when administered by intramuscular injection and is reported to have a similar duration of action to that of nandrolone decanoate via this route.
See also
List of androgen esters § Nandrolone esters
References
Abandoned drugs
Anabolic–androgenic steroids
Nandrolone esters
Progestogens | Nandrolone cyclotate | Chemistry | 218 |
68,563,126 | https://en.wikipedia.org/wiki/Laboratoria | Laboratoria is an organization empowering women who dream of a better future to start and grow careers in technology. It seeks this through totally remote bootcamps, focused on technical and life skills, aimed at women who haven´t been able to start their careers. After the bootcamp, they guide their graduates to find quality jobs in the tech sector. Laboratoria also has a very powerful community of more than 3,500 women who are each playing a key role in a more diverse and competitive digital economy.
History
Laboratoria was created to revert the disadvantages women face in accessing quality jobs in the growing digital economy. It began with a pilot training program for 15 women and rapidly expanded, with 3,500 graduates.
Since its foundation in Lima, Peru, in 2014, Laboratoria has expanded to Bolivia, Brazil, Chile, Colombia, Costa Rica, Ecuador, México, Panamá, Paraguay and Uruguay. Today, due to it being a remote first company, it has been able to reach more countries in Latin America and beyond. Women from different cities and regions have been able to go through the bootcamp, thanks to the absence of geographic boundaries. It also has over 120 team members working daily to have a more profound social impact in the region.
Over 3,500 women have graduated as web developers and UX designers, with an average job placement rate of 79%. Laboratoria is also a source of female tech talent for leading companies in a wide variety of industries. More than 1,100 companies have hired Laboratoria talent.
Awards and recognitions
Mariana Costa was recognized in the Merco 2023 ranking, for her leadership work in Laboratoria, in the Technology category.
Mariana Costa was selected by Bloomberg for its Catalysts program, which highlights founders, activists, entrepreneurs, policymakers, scientists, visionaries, and even elected officials whose remarkable work in business, philanthropy, and government, especially in emerging markets, demands recognition.
Laboratoria was highlighted as one of the companies that leaves its mark on the digital ecosystem in the eWomen category of eCommerce Day Peru 2023, organized by the Lima Chamber of Commerce.
Gabriela Rocha received the Latin American Leaders Award from The Global School for New Leadership in 2022.
Mariana Costa was selected by Fortune magazine in its 40 Under 40 ranking in the Tech and Innovation section in 2022.
Laboratoria was recognized as one of the 100 most promising edtech startups in Latin America and the Caribbean by HolonIQ in 2022.
Laboratoria was selected to be part of the National Inclusive Employment Report (INEI) 2022 in Colombia, as part of the call for success stories.
Forbes Peru places Mariana Costa among the 50 most powerful women in the country in 2022. The special issue of the magazine highlights the contribution of Peruvian women in different areas, such as business, economy, academia, art, science and technology, among other sectors. In order to choose the 50 women, the resources they manage in their organizations and the impact they generate in their communities were evaluated.
Mariana Costa was chosen as one of the most influential, innovative and pioneering people in fintech, e-commerce, politics and digital infrastructure in the RoW100: Global Tech's Changemakers ranking (2022).
McKinsey & Company recognizes Mariana Costa on its The Committed Innovator list, which highlights women in corporate, academic and entrepreneurial fields around the world who are creating groundbreaking breakthroughs in some of the most challenging issues on the planet. These women leaders are pioneering, expanding frontiers and building legacies in agriculture, banking, beauty, education, fashion, health and technology, 2021.
Mariana Costa is recognized by Google.org as a "Leader to watch" in 2022. Google's philanthropic arm selected seven leaders in the world, including the Peruvian entrepreneur, the only representative from Latin America.
Laboratoria was recognized as one of the 100 edtechs in Latin America in 2021 by HolonIQ, an intelligence platform that provides data and analysis of developments in the global market and annually publishes a ranking of the most promising startups in the region. The evaluation was made after a review of more than 2,000 edtechs.
Mariana Costa was chosen by the Project Management Institute (PMI), an American organization with nearly 500,000 members in almost 100 countries, as one of the winners of the Future 50 in 2021, which features emerging leaders who are creating, building and transforming the world through remarkable projects, 2021.
Bloomberg online presented a list of the 100 Innovators of 2021, in which they selected the Latinos who, during the pandemic, not only invented models, but also corrected their steps and even reinvented themselves to adapt to this new economic and social scenario.
Mariana Costa Checa is part of the Wonderful Women of the World 2021 anthology, which – in comic format – shows the work of outstanding women around the world.
Holon IQ 2020 Latam EdTech 100
Transforming Lives Award A lquity, 2019
Women Leading in Technology and Impact, Engineering for Change, 2018
TEDxPlaceDeNations Speaker, 2018
Equals in Tech Award – ITU, UN, Internet Society, 2018
Change Agent Abie Award - AnitaB.org – Grace Hopper Celebration, 2018
Ashoka Fellow – Mariana Costa, as Cofounder and CEO, since 2017 to the present day
World Summit Awards, 2017.
MIT Inclusive Innovation Challenge – Winner Matching Category, 2016
BBC – 100 Most Influential Women, 2016
DAI Innovation Into Action Challenge, 2016
Google Rise Awards, 2015.
References
External links
2014 establishments in Peru
Non-profit organisations based in Peru
Organizations for women in science and technology
Computer science education
Women in computing
Social entrepreneurs | Laboratoria | Technology | 1,156 |
18,934,072 | https://en.wikipedia.org/wiki/Lactarius%20blennius | Lactarius blennius (commonly known as the slimy milkcap or beech milkcap) is a medium-sized mushroom of the genus Lactarius found commonly in beech forests in Europe, where it is mycorrhizal, favouring the European beech (though associations with other trees are known). It was first described by Elias Magnus Fries. Though its colour and size vary, it is distinctive because it is slimy when wet and exudes copious amounts of milk. It has been the subject of some chemical research, and it can be used to produce pigments and blennins. Blennins, some of which have shown potential medical application, are derived from lactarane, a chemical so named because of their association with Lactarius. The edibility of L. blennius is uncertain, with different mycologists suggesting that it is edible (though not recommended), inedible or even poisonous.
Taxonomy and naming
Lactarius blennius was first described by Swedish mycologist Elias Magnus Fries as Agaricus blennius in 1815, before being given its current binomial name by the same author in 1838. Within the genus Lactarius, it is closely related to Lactarius cinereus, another Lactarius species that also favours beech. It has been suggested that the two species (forming a group) could have a coevolutionary pathway with beech. The specific epithet is derived from a Latin adjective blennius, meaning "slimy". Lactarius mushrooms are commonly known as milkcaps, and L. blennius is known as the Slimy Milkcap or the Beech Milkcap.
Lactarius blennius is synonymous with Agaricus blennius (the name under which Fries first described the species in 1815) and Agaricus viridis, a name given earlier by Heinrich Schrader, in 1794. Galorrheus blennius (a name proposed in 1871 by Paul Kummer), Lactarius viridis (proposed in 1888 by Lucien Quélet) and Lactifluus blennius (proposed by Otto Kuntze in 1891) are also now recognised as synonyms. Lactarius albidopallens was originally described as a form of L. blennius as Lactarius blennius f. albidopallens by Jakob Emanuel Lange in 1928, before being classified as a separate species by J. Blum. Lange also described Lactarius blennius f. virescens, which is now recognised as nomen invalidum (an invalid name). Lactarius fluens is another species that has been included in L. blennius; originally described in 1899 by Jean Louis Émile Boudier, in 1999, German Joseph Krieglsteiner suggested that it is actually a variety of L. blennius, naming it Lactarius blennius var. fluens. However today L. fluens is normally regarded as a related but separate species, distinguished by a pale cap margin, less sliminess and a deeper cream gill colour.
The situation with Lactarius viridis is similar but with a different outcome; it was first described as a separate species by Quélet in 1888, and then in 1980 A. Marchand proposed that it is in fact a variety of L. blennius, naming it Lactarius blennius var. viridis. In this case the synonymy has become accepted.
Description
Lactarius blennius has a flattened convex cap that is 4–10 cm (1.6–4 in) across that later becomes depressed in the centre. In colour, it is pale olive to a greenish grey, sometimes a dull green or pale grey-sepia, and has blotches of darker colouration in concentric bands, though the colour can vary greatly. Heavily spotted specimens are also known, and a very brown specimen similar to Lactarius circellatus was recorded in Scotland. The cap is very slimy when moist and has a margin that is curved inwards. The stem is a paler colour than the cap, but also very slimy, and measures from 4–5 cm (1.6–2 in) tall by 1–1.7 cm (0.4–0.7 in) thick, tapering a little towards the bottom. The flesh is whitish, similar in colour to the gills, which later become a creamy or pale buff colour. The gills turn a brownish-grey colour when wounded, and are crowded. In shape, they are slightly decurrent or adnate, meaning that they run a small way down the stem in attachment, or that they are attached to the stem by the whole depth of the gills. The milk is white and dries grey, and is very plentiful. L. blennius spores leave a creamy print, and are elliptic with low warts joined by ridges with a small number of cross-connections, measuring from 6–9 by 5.5–7 μm.
Distribution, habitat and ecology
Lactarius blennius is very common and is found in broad-leaved woodland, favouring beech; it is most associated with Fagus sylvatica, the European Beech, though it has also been observed growing in association with species of oak. It forms an ectomycorrhizal association with trees, and can grow on a wide variety of subsoil types, but is more typical of acidic soil. It is found between late summer and late autumn, and is native to Europe. The distribution of the mushroom coincides with the distribution of beech. In the British Isles, the species is one of the one hundred most common mushrooms. Other areas in which it has been recorded include Sweden, France, Italy, and Poland.
Uses
Mycologist Roger Phillips claims that L. blennius is edible when cooked, but not recommended, while others describe it as inedible or even poisonous. The milk tastes very hot and acrid.
Lactarius blennius has been the subject of some research in chemistry. Lactarane derivatives (known as "blennins") have been acquired from the mushroom, including the lactone blennin D, and blennin A, which was first isolated from this species. Lactaranes are chemicals so named because of their occurrence in Lactarius species. Blennins have been shown to be potentially useful- blennin A, for instance (a lactarane-type sesquiterpene) has been shown to be an anti-inflammatory, having a strong inhibitative affect against leukotriene C4 biosynthesis. L. blennius can also be refined to create a green pigment, known as blennione.
See also
List of Lactarius species
References
External links
Fotos in Mushroom Observer
Fungi described in 1815
blennius
Fungi of Europe
Inedible fungi
Taxa named by Elias Magnus Fries
Fungus species | Lactarius blennius | Biology | 1,439 |
14,557,673 | https://en.wikipedia.org/wiki/The%20Guild%20%28web%20series%29 | The Guild is an American comedy web series created and written by Felicia Day, who also stars as Cyd Sherman (AKA Codex). It premiered on July 27, 2007, and ran until 2013. The show revolves around the lives of a gamers' online guild, The Knights of Good, who play countless hours of a fantasy MMORPG video game referred to as The Game. The story focuses on Codex, the guild's Priestess, who attempts to lead a normal life after one of her guild-mates, warlock Zaboo (Sandeep Parikh), shows up on her doorstep.
During The Guilds first season episodes were uploaded to YouTube and the series website. After the first season, The Guild entered a partnership with Microsoft, and episodes of the second through fifth seasons premiered on Xbox Live Marketplace, Zune Marketplace, and MSN Video before being later made available on the official Guild website, YouTube, and iTunes. According to Day, Microsoft's business model changed after season five; Day wanted to keep ownership, so the episode premieres moved to Day's YouTube channel Geek & Sundry. The series is also available via DVD and streaming on Apple TV. In 2013, after the end of the sixth season, Day confirmed that the web series is complete.
Since its release, The Guild has received several accolades, including six Streamy Awards and four IAWTV Awards.
History
The Guild was written and created by Felicia Day, an avid gamer, in between acting roles in several American television shows and movies. After two years of gaming, Day decided to make something productive from her experiences and wrote the series as a sitcom television pilot. The series was purposely kept generic to avoid copyright problems and to appeal to a wider audience of massively multiplayer online role-playing game (MMORPG) fans, but Day based it on her experience with a World of Warcraft addiction.
Day also hoped to show that the stereotypical man living in his parents' basement is not the only kind of gamer. She decided to produce the series online with Jane Selle Morgan and Kim Evey. Day already knew Sandeep Parikh and Jeff Lewis from Empty Stage Comedy Theatre, a Los Angeles-based comedy theatre, and their roles were written for them. The rest of the cast was filled through auditions.
After filming the first three episodes in two and a half days, they ran out of money. After donations were solicited through PayPal, the fourth and fifth episodes were almost solely financed by donations.
Format
Each episode opens with Codex (Felicia Day) recapping the previous events in the story in the form of a video blog. Usually, it gives the audience a recap of the previous episode and shares Codex's feelings on the subject. The video blogs appear to be outside the timeline, as she is usually wearing an outfit (typically her pajamas) different from that in the episode itself, though some blogs take place in the time line with other characters or situations interrupting Codex. Each season is divided into 12 episodes (with the exception of season 1, which is divided into 10 episodes).
Plot
Season 1 (2007–2008)
Cyd Sherman struggles to limit her time online, where she games as her alter ego Codex, a member of the Knights of Good. After the guild realizes that Zaboo has been offline for 39 hours, he appears on Codex's doorstep. Zaboo misunderstood Codex's in-game chats as flirting, and became a stalker living in the same apartment.
On the in-game side, trouble also arises when Bladezz is banned from the game for using a macro (to spam homophobic slurs "a few thousand times") in the trade house. Codex uses this as an excuse to have the guild help her with her Zaboo problem. The guild (except Bladezz) reluctantly meets up in person—for the first time—at Cheesybeards, a local restaurant, only to find out that Vork had transferred all of their in-game valuables to Bladezz's account as part of a team building strategy. If they decided to kick out Bladezz, they would lose everything.
Things get worse when Bladezz begins to slander the Knights of Good by showing inappropriate videos of the members' characters, and Codex is no closer to getting Zaboo to go home. Then, Zaboo's home comes to him in the form of his overbearing mother. Zaboo confesses that his mother controls every aspect of his life besides the Internet, which she is beginning to read about. He saw this as his only escape.
Codex comes up with a plan to bring Bladezz down, using Zaboo's stalking skills. Zaboo finds out about Bladezz's modelling career and blackmails him into giving the gold and equipment back to the Guild. The Guild then fights off Zaboo's mom, and Bladezz redeems himself by landing the final blow. Codex soon realizes that she got Zaboo's mother's loot- Zaboo.
Season 2 (2008–2009)
Zaboo's mother takes revenge for losing Zaboo by having Codex evicted. Codex and Zaboo move into a new apartment, where Codex meets a new love interest: Wade (Fernando Chien), a stunt man. Codex tries to get Zaboo to move out by telling him that he needs to level up before they can be together. She arranges for him to live with Vork, who will take in-game gold as rent, something Zaboo is really good at: farming. Codex focuses on trying to get Wade interested in her.
The Guild finds a valuable in-game orb which Clara and Tink fight over. Just as Vork lets it go up for bid, Clara's children unplug her computer from the Internet and, upon re-connecting, Clara finds out Tink wins it. Clara vows revenge on Vork for giving it to Tink and spends an entire weekend betraying Vork by corpse camping him on an alternate account as well as searching for her own orb.
Bladezz believes Tink is romantically interested in him and begins to max out his mother's credit cards to buy her stuff, when, in fact, Tink is using him to get what she wants. Vork is annoyed with Zaboo's lack of logic and his antics in trying to 'man-up' for Codex. Codex finds out that the stunt-man has a "stupid tall hot girlfriend," Riley (Michele Boyd).
The Game announces that the online play will be shut down for maintenance for four hours, during which Vork plans a strategy lecture for Zaboo and Bladezz, while Codex plans a quiet party with Clara and Tink. Bladezz coerces Vork to abandon the lecture in favor of a poker game (offline), hoping to make up some of what he spent on Tink. Clara advertises Codex's party and it becomes a crowded kegger.
Among Clara's random invitees, Wade and Riley come to the party. After finding out that Riley is Wade's roommate and Wade is single, Tink and Clara try to hook Codex up with him. Zaboo, learning of this, persuades Vork and Bladezz to go to Codex's party to try to stop it. Vork discovers that Clara has been attacking him, and begins to question his quality of leadership. Bladezz confronts Tink about their relationship; upon learning that he has been used, Bladezz steals Tink's laptop and deletes her character. Meanwhile, Zaboo walks in on Wade and Codex kissing and challenges Wade to a fight. Wade is a much better fighter, but Zaboo's seriousness about Codex leads to Wade giving up his interest in her. Codex yells at Zaboo that she doesn't like him, and he leaves dejected. Then Codex sees a drunken Clara kissing with Wade, and decides to chase after Zaboo to apologize, but is hurt when she sees him making out with Riley.
Season 3 (2009)
Codex was able to recover from the disastrous party by the announcement of the new expansion pack for the game, Spires of Dragonor. The Knights of Good are first in line at GameStop until a rival guild, the Axis of Anarchy, cuts in front of them. After the Axis tricks a GameStop worker into sending the Knights to the back of line, Vork, still not over the events of the party, resigns as Guild Leader. Codex is elected as his successor, causing Tink to leave the Knights and join the Axis.
While Vork goes on a self-discovery journey, Clara's husband George demands that she spend more time with the family after discovering her gaming has severely distanced her from him. As a result, Clara proposes that he take Tink's place after auditions for a sixth member fail. Riley, who becomes increasingly domineering to Zaboo, offers to join, but Codex chooses Clara's husband instead, adding "Mr. Wiggly" to the Guild. Meanwhile, Bladezz begins to be targeted by Tink and the Axis of Anarchy, who expose his modelling alias to his school and plant weapons in his locker; later, Bruiser (J. Teddy Garcia), a member of the Anarchists, seduces his mom. Codex issues a message on the game's public forum to stand up against the Axis for the behavior, and in retaliation the Axis puts a bounty on the Guild. Mr. Wiggly unknowingly gives away information about the Guild to other gamers in exchange for loot, which leads to his expulsion from the Guild. With this, he tells Clara to quit the game, and she does to save her marriage.
To end the Axis's harassment of Bladezz, Codex and Zaboo track down the Anarchist Valkyrie at his job, where is he playing the game on company time. After they take away some of his character's possessions and threaten to expose him, Valkyrie tells them where and when the next Axis of Anarchy meeting will take place. Vork returns after regaining his confidence to lead and, with Codex, reassembles the Guild to challenge the Axis at the Internet café where they planned to have a group raid. The battle begins, but both sides lose members quickly. Some of the Knights die in-game when their real-life problems manifest: Clara's husband shows up, angry that she is playing the game; Riley destroys Zaboo's computer for not meeting her demands. Clara tells her husband that they are going to have another child and he forgets about their argument and redeems himself in the eyes of the guild by helping Clara kill the Anarchist Kwan in game. Zaboo breaks up with Riley, who then proceeds to make out with Venom.
Finally, only Codex is left to face off Tink and Axis leader Fawkes (Wil Wheaton). After Codex makes Bladezz apologize to Tink, Tink decides that the Axis members are even bigger jerks than she can stand and lets Codex kill her in-game. Codex, in a hallucinatory conversation with her game character, musters the courage to defeat Fawkes. The Knights welcome Tink back into the guild, and Bladezz makes tentative peace with the Axis member who seduced his mother. Fawkes invites Codex for drinks; she initially refuses but, in a twist ending, wakes up in bed with him the next morning.
Season 4 (2010)
An unexpected and unintentional one-night stand with Fawkes (Wil Wheaton) causes Codex to stress over what the guild thinks of her and persuades him to cover for her in a pretend relationship. But after spending more time together, Codex realizes he is a "total tool-bag" and reevaluates her criteria for relationships with men. Her computer breaks and she is forced to get a job at Cheesybeards to pay for repairs but has no idea how to fulfil the expectations of her boss, Ollie (Frank Ashmore).
Zaboo tries to be a good friend to Codex during her fake relationship with Fawkes instead of trying to win her love. He dives into this new pursuit with his usual smothering intensity. When the truth of the relationship is revealed he realizes that his feelings for Codex have changed and he wants to be her friend.
An earnings competition for a new guild hall sparks a real-life business for Tink and Clara that strengthens and strains their friendship.
Vork enlists Zaboo's mother, Avinashi (Viji Nathan), for her "brilliant economic mind" in his pursuit of his vision for the guild's hall and he sets up a stock market and loan company that is bankrupting players. However, her smothering tendencies enrage him to the point that he "make[s] a giant gesture that's really inappropriate" and proposes marriage in an attempt to repulse her. To his horror she accepts.
Codex and Bladezz film an online Cheesybeards commercial but the result is so horrible that it spawns a series of prank calls to the establishment. Ollie is furious and fires Codex. The guild helps Codex get her job back by organizing a celebration at Cheesybeards that attracts a large population of gamers. Bladezz attempts to perform a magic trick involving fire, which ends up torching the restaurant (costing Codex and Bladezz their jobs).
Zaboo begs Codex to intercede in the upcoming nuptials between his mother and Vork. And when Zaboo reveals he has used the money from auctioning a romantic painting of Codex and Fawkes he had commissioned to buy her a new computer she is touched by the gesture and resolves to break up the wedding.
Avinashi and Vork are about to speak their vows to each other, at a virtual wedding ceremony in the newly purchased prison-like Knights of Good guild hall, when all of the guild members object. Codex manages to convince Zaboo's mother that it is wrong to marry "someone [she] can't stand in order to be close to someone who doesn't want to be near [her]". Zaboo helps by suggesting that she visit every few weeks when she gets lonely, causing Codex to realize that he possesses all the qualities on her new litmus test, and considers a relationship with him.
The season wraps up with an official gamemaster crashing the ceremony to put an end to Vork's "Trogothian Stock Market" scheme. Codex convinces the GM, Kevinator (Simon Helberg), to change the design of the guild hall to the "bitchin' fairy palace" that Tink and Clara wanted. Kevinator is impressed to meet Bladezz, who has become an internet celebrity and invites the whole guild to a gaming convention.
Season 5 (2011)
The Knights of Good travel to MegaGameORama-Con, a three-day gaming convention. Bladezz believes that he is invited by Kevinator as a special guest, but his name is not on the invite list. With all nearby hotels booked, Rachel, a member of the convention staff, manages to secure a room for them. However, it is not offered for free, and Bladezz convinces the rest of the guild that he will clarify the situation to Kevinator. Meanwhile, Codex is more interested in getting close to Zaboo, but he becomes engrossed in attending the events and panels.
On the first day of the convention, Bladezz and Vork discover that Kevinator had been fired from The Game before the day of the convention and Bladezz was one of his joke invites. To compensate for hotel fees, both of them start up a photo booth for the Cheeseybeard's pirate. Tink attempts to sell the T-shirts she and Clara made but is forced to find a booth to avoid from being caught by the convention staff for selling without a permit. When she and Clara come upon a steampunk-themed booth, Clara is more interested in it than selling the shirts. Zaboo is denied entry to a panel because the seats are full, causing him to form a seat-saving network.
Codex tries out the new demo at The Game's booth, but unknowingly insults the creator, Floyd Petrovski (Ted Michaels). She becomes even more preoccupied when Zaboo spurns her advances and is continuously stalked by a convention-goer in a furry costume. When she follows Floyd to apologize, she discovers that he plans to sell The Game to a mainstream market. Codex becomes concerned about the future of the game, which is the only thing in her life holding her friendships together.
Tink, who continuously changes costumes to hide her identity, reveals to Codex at a party that she is hiding from her adoptive family, who have attended the convention, fearing that they will discover her switching majors from pre-med to fashion design. Codex arranges a dinner with her family to reconcile against Tink's will. Meanwhile, Clara tries to join the steampunk group and is trained as their fourth member to help them win the costume contest, but the members of the group ultimately turn her away. Zaboo has become so preoccupied with his seat-saving network that he briefly goes power-hungry. He is stopped by Clara, who brings back his old personality, ending his involvement with the seat-saving network.
Bladezz and Vork's booth becomes successful, but Vork rejects all of the celebrities who want to spend time with Bladezz. His attention, however, is turned towards Madeline (Erin Gray), an actress who played his favorite character, Charity, on the show Time Rings. The two are invited to a party that night, but Bladezz realizes that all the celebrities lead normal lives, finding them boring. Still, he rejects Rachel and her friends for the celebrities and openly humiliates them. Vork, on the other hand, ends up offending Madeline after he criticizes her decision to leave her show.
The next day, Bladezz has lost all support from the celebrities and his fans, so he is unable to continue the Cheeseybeard pirate's photo booth. Zaboo helps Clara build a steampunk-themed blimp to help her win the costume contest. Codex and Tink discover that Codex's stalker is Fawkes, who wants to join their guild after the Axis of Anarchy broke up, but Codex rejects him. The girls later eavesdrop on Floyd's conversation and discover he plans on revealing his decision at the costume contest that night. Both of them convince the rest of the Guild to help them save The Game from going "freemium". The Guild is able to stop the changes with much success: Clara wins the costume contest, Bladezz is able to win back his fans, and Vork reconciles with Madeline. As all of them leave the convention the next morning, Floyd has decided to give Codex a job.
Season 6 (2012–2013)
Codex begins her new job working for Floyd Petrovski at the headquarters for "The Game", only to discover that he's a thoughtless tyrant who immediately turns all the other employees against her. Meanwhile, Tink discovers that the men she manipulated for services and gifts have all slandered her on local websites, losing all of her connections. Bladezz gets kicked out of his house by Bruiser and spends time at Clara's, convincing her long-suffering husband that she is devoted to her children by uploading videos of her parenting to the Internet, though he is more interested in monetizing the videos. Vork, who is dating Madeline, becomes disillusioned when Zaboo uncovers photos of her protesting nude, while Zaboo suffers separation anxiety from the members of the Guild going offline, seeking refuge from a collage of his ideal "sweetheart."
Codex is pressured by her co-workers to convince Floyd to release the underwater expansion pack they have been planning for months but is forced to do menial chores in order to appease him. When the Guild visits her workplace, Tink steals Codex's key to the testing server and initiates a casual relationship with Donovan (Corey Craig), where they agree that he will do chores for her if she spends time with him. Unbeknownst to her, she begins to fall in love with him for real. Zaboo, who enters the server posing as an IT technician, becomes smitten with Sabina (Justine Ezarik), an NPC of The Game and the spitting image of his ideal girl.
Vork, who has gotten through with an argument with Madeline about his personal goals, confronts Floyd about his unanswered complaints about The Game. This gets his character permanently banned, and he retaliates by protesting and gaining support from other gamers. Meanwhile, Bladezz is forced to spend time with Wiggly while Clara continues making videos. When Clara becomes Internet-famous, other parents turn to her for advice, one of them being Bladezz's mother. Clara encourages her to keep dating Bruiser, causing Bladezz to convince Wiggly to quit his job.
The underwater expansion patch notes are leaked onto the Internet, greatly intensifying the protest. Codex is unsuccessful in finding the culprit but convinces Floyd to release the expansion pack anyway. Donovan reveals to Tink that he was the one who caused the leak in order to push Floyd to release the expansion pack, and Tink tells him that Codex and Vork are in the same guild. He uses this information against Floyd to blame the leak on Codex and gets her fired. Vork's protest culminates in a riot, but his acts have renewed Madeline's faith in him and the two reconcile.
As her final act for Floyd, Codex quells the rioters by questioning their acts and informing that their poor attitudes contributed to the problems at the Game HQ. Floyd unexpectedly steps out and challenges the crowd to insult him to his face instead of typing online insults, but the entire crowd congratulate him on his work and cite their insecurities as part of their bad behaviors. Inspired, Floyd announces a troll-themed add-on for the Game. By the end of the day, Clara is successful in convincing Bruiser to break up with Bladezz's mother and secures a position at a vlogging network, Tink and Donovan begin a relationship, and Zaboo discovers his real-life Sabina. Codex, happy with getting her job back and realizing how much her friends are loyal to her, makes a final vlog and tearily shuts down her computer, bringing the season (and the series) to a close.
Characters and cast
Knights of GoodCodex (real name Cyd Sherman) is the Priest. Codex is shy and non-confrontational, tending to panic under stress. Outside the game she is a concert violinist (and former child prodigy), unemployed after setting fire to her boyfriend's cello. She is an addicted gamer who tries at first to control the time she spends online, but fails. For this reason, her therapist drops her. At the beginning of the series she is quite reclusive with no real-life friends; she is often self-conscious and awkward around men. Codex is portrayed by creator Felicia Day.Zaboo (real name Sujan Balakrishnan Goldberg) is the Warlock. Zaboo describes himself as a "HinJew", having a Hindu mother and Jewish father. He shows great skill with computers; for example, his stalking of Codex included obtaining (presumably through the Internet) the floor plan of her apartment and all her past residences. His obsessive attitude toward Codex reflects his mother's smothering. When talking, Zaboo often uses "-'d" after some key word or expression, self-commenting on what he just said (e.g. bladder'd, testosterone'd). While Zaboo doesn't appear to have a profession, he admits having attended college for four years (to which his mother drove him every day). Zaboo is portrayed by Sandeep Parikh.Vork (real name Herman Holden) is the guild leader and Warrior. He enjoys managing the guild and budgeting, and believes only in rules and logic. He lives frugally (and illegally) on his late grandfather's Social Security checks and is a certified notary public. When he became Guild Leader he "cut the fats of life" including electric power; he steals his senile neighbor's wifi (and shed), and keeps his food cold by buying ice with food stamps. In the penultimate episode of season 3 he reveals that he can speak fluent Korean; in season 4, he speaks Hindi to Zaboo's mother and claims to know all languages. Vork comes to believe that shared hatred of him is what keeps the guild together. In Season 4, his desire to own a guild hall leads him to manipulating an in-game exchange market, nearly causing him to be banned from the game. Vork is portrayed by Jeff Lewis.Bladezz (real name Simon Kemplar) is the Rogue. He is a high school student who spends most of his time outside of school in his mom's garage playing the Game. He is rude to the other male guild members, hits on the female guild members, and often makes lewd sexual jokes and comments. He is shown to be trumped by his tomboyish little sister many times throughout the series. He is worried about being sent to military school, and to save up for college his mom forced him into modeling; using the alias "Finn Smulders" in order to keep it a secret from his fellow high school students. In seasons 4 and 5, he becomes an Internet meme. Bladezz is portrayed by Vincent Caso.Clara (real name Clara Beane) is the Frost Mage. Clara is a neglectful stay-at-home wife and mother, college partier, and ex-cheerleader. Her three children are all young, with the youngest still breastfeeding. Though proud of her children, she tends to put gaming before her family, and sometimes tries to mix the two, recruiting her husband "Mr. Wiggly" to the guild. She uses her real name as her avatar name because her kids saw her old name, "Mom-inatrix". Clara expresses a ditsy, scatter brained, and eccentric personality with occasional bursts of insight. In the Season 5, Clara proves herself to be a capable mother -figure when she stops Zaboo from going mad with power and lack of sleep. Clara is portrayed by Robin Thorsen.Tinkerballa (real name April Lou) is the Ranger. Tink distances herself from the guild, trying not to let them know anything about her personal life, she even keeps her real name a secret from her fellow guildies introducing herself as Tinkerballa. Her real name isn't revealed until the fifth season. In reality, Tink is adopted and has two caucasian sisters. She also has been lying to her parents about being a pre-med student, when she has actually switched courses for a degree in costume design. She is shown to have a huge video game addiction, always having an alternate game in hand when not playing the guild's game, even when raiding. She is cold and manipulative, and uses men to get what she wants, including Bladezz who deletes Tink's character to avenge himself after being used by Tink. Following this, and Vork's refusal to punish Bladezz, she leaves the Knights of Good and joins the Axis of Anarchy, but later finds them too "douchey" even for her (she even says that she went on a date with Fawkes to join). She rejoins the Knights of Good during an in-game showdown with the Axis of Anarchy when they call her "Tainterballa" and she allows her avatar to be killed off intentionally to give Codex the shot at victory for the guild. Tink is revealed to be possibly the most social of the group although is incredibly grounded in the online world. In Season 5, Codex reunites Tink with her family at the gaming con. Tink is portrayed by Amy Okuda.
Temporary membersMr. Wiggly (real name George Beane) is a Hunter. He is Clara's husband, nominated by Clara to replace Tink in Season 3; Codex hastily accepts him in order to prevent Zaboo from recruiting Riley. He is clearly inexperienced in gaming, mentioning that the last game he played was Pong (which Bladezz was unfamiliar with). Mr. Wiggly wants to spend time with Clara, but is at his wits' end with her distraction and infidelity. George is shown to be a conventional man who has a sense of responsibility, helping Clara when she spontaneously starts a gamer company. He is displeased when Clara leaves unannounced for the gaming con. Mr. Wiggly is played by Brett Sheridan.
Axis of AnarchyFawkes is the leader of the Axis of Anarchy. He always wears a black kilt and often wears a black "Axis of Anarchy" T-shirt. In person he speaks with a cool, calm, almost polite tone, though he is prone to angered outbursts when online. He seems to be quite educated as well, as he is constantly quoting philosophers, authors, or figures of history. He often demonstrates that he does not believe in following rules, unless it benefits him. Because of their top ranking, he expects constant perfection from his guild. He is also quite full of himself and manipulative, convincing people they are into him. After the Knights of Good defeat the Axis of Anarchy at the end of Season 3, Fawkes invites Codex for drinks and although she doesn't intend to go, she does and ends up having a one-night stand with him. Attempting to justify this to herself and the Guild, she tries seeing where a relationship with Fawkes would go but he claims he is uninterested in dating and eventually she dumps him. However it emerges that Fawkes has developed feelings for Codex and asks her out properly, but she turns him down flatly. He returns in Season 5, revealing that the Axis broke up (claiming no fault of his own). Fawkes is played by Wil Wheaton.Venom is the only woman in her guild, until Tink joins. She is a paraplegic and uses a wheelchair, but seems to have no problem exploiting her disability for personal gain. She has a violent attitude and seems to dislike her guildmates. On at least two occasions she threatens suicide to get her way, and, when her character is killed in-game, feels ecstasy at this vicarious death. She works as a substitute art teacher at Bladezz's high school. Played by Teal Sherer.Bruiser is the guild's healer, and a corrupt police officer. Bruiser is probably the largest, loudest, and most vulgar member of the Axis. He had sex with Bladezz's mother to torment Bladezz, and in Season 6 is continuing to see her. Played by J. Teddy Garces.Kwan is a champion StarCraft player and earns millions playing in South Korea. He only speaks Korean, and has a female assistant named Nik (played by Toni Lee) who massages his hands and translates for him. He seems to be able to understand some English, and it's possible that Fawkes can understand some of what he says (as his translator does not translate what Kwan says into English). Played by Alexander Yi.Valkyrie (alt-character Artemis) is the attempted joker of the guild, though his jokes seem to be funny only to himself. Based on dialogue with his off-screen boss, he works for some form of design or decorating firm – he claimed to be dealing with a client whose damask came in the wrong color. He also has web skills, claiming to be the one who created finnsmulders.com. He also plays two girl characters because he claims to like looking at girls, although it is strongly implied he might be a closet homosexual. Played by Mike Rose.
Game HQFloyd Petrovski is the creator of the Game and head of the company that produces it. While at Megagame-o-ramacon Floyd overhears Codex criticize parts of the upgrades available for playtest at the convention. After Codex apologizes for her comments and gathers the guild together to interfere with the Game's sale to a larger company, Floyd recognizes Codex's passion for the Game, and hires her as an assistant. Floyd proves to be a difficult boss, quickly alienating Codex from much of the staff. Floyd is played by Ted Michaels.Roy Aquino (Derek Basco), the graphic designer of the Game. On Codex's first day, Floyd lets her have Roy's office without his permission, causing Roy to dislike Codex from the very start. He subtly harasses Codex with drawings and bulletins. He is shown to have a stutter when under stress.Theodora (Alexandra Hoover), the Game COO and head producer. Despite being austere and cold-hearted, she is also extremely clumsy and tends to cover this up with awkward recoveries.Sula Morrison (Sujata Day), the hyperactive community coordinator. She wears glasses despite not having any vision impairment, claiming they make her appear smarter.Donovan (Corey Craig), the lead programmer and nephew to Floyd. Despite being handsome and athletic, he avoids people most of the time; Floyd describes him as a savant and Tink questions whether he has Asperger's Syndrome or not. Tink, nonetheless, gets him into doing her homework and yet develops feelings for him. He graduated top of his class from Caltech.
Other charactersZaboo's mother (Avinashi Goldberg) epitomizes the over-controlling mother. She had Zaboo microchipped to keep track of his movements, punches Codex for (in her belief) trying to take her son away from her, manipulates him through a series of probably false ailments, and gets Codex evicted for helping him break free of her. She returns in Season 4, attempting to develop a real relationship with her son and ends up assisting Vork in earning gold to purchase a deluxe guild hall. She does manage to reconcile with Zaboo. She is played by Viji Nathan.Dena is Bladezz' precocious little sister. She is first seen when she arrives at the table at Cheesybeards, just after Bladezz has informed the Guildies that he is in control of all the Guild gold and equipment, ruining his big exit. Dena often practices playing bass guitar in Bladezz' basement, to his annoyance, and reads Sun Tzu's The Art of War (along with building Civil War dioramas). In Season 4, she trained Bladezz in being an actor (calling him terrible). Dena is played by Tara Caso, the sister of Vincent Caso who plays Bladezz.Wade Wei is Codex's attractive neighbor and brief love interest. Not a gamer himself, Wade works as a martial arts stunt double; on first meeting Codex, he bumps into her and falls down some stairs, practicing a new stunt. He's fond of showing off his moves and flirting with Codex, making her extremely nervous. Having a queasy stomach, Codex vomits on him upon seeing him in makeup from a zombie movie he is playing in. He harbors a revulsion for gamers, expressing his desire to punch them. Ironically, he describes Codex's gaming-derived knowledge of weaponry as "sexy," though it is worth noting that she does not explain how she knows so much about weapons when he makes the compliment. In episode 10 of season 2, it was revealed that he did motion capture stunt work for the Game. Wade is played by Fernando Chien.Riley is Wade's roommate with benefits and temporarily dated Zaboo. Riley is an FPS gamer and is ranked in Halo on Xbox Live. Riley is very dominant and enjoys submissive underdogs like Zaboo, and later Codex. At first she was thrilled to meet Codex, another girl gamer, until after she learned that Codex was an MMORPG player, the two began a grudging rivalry. This parodies the normal relationship between MOG and MMORPG players. In the finale of Season 3, Riley straddles Venom and starts making out with her to get back at Zaboo for breaking up with her. Riley and Venom then start a relationship, which goes well into Season 4 Episode 10, where they're seen discussing Wench outfits. The character of Riley is based on Team Unicorn member, Rileah Vanderbilt, and played by Team Unicorn member Michele Boyd.Ollie is the manager of Cheesybeards. He runs his restaurant in a very casual style, allowing Bladezz to use a computer while working at the grill. He speaks entirely in pirate-slang and uses a hook on his left hand (which is hinted to be real). Ollie is responsible for Codex getting a job at the restaurant, after she says she can improve advertising and increase business (though Bladezz sabotages these efforts). Ollie is slightly at odds with Jeannete, who strongly disapproves of Bladezz's slacker work ethic. He first appeared in episode 3 of season 4 and is played by Frank Ashmore.Jeanette is Bladezz's superior at Cheesybeards. She is fed up with his horrible work ethic, but is at odds with Ollie (who is okay with Bladezz). At the end of Season 4, it is revealed she was one of Fawkes' one-night stands and proceeds to beat him up (as she knows mixed martial arts). Jeanette was the first new character to appear in Season 4 and was played by Tymberlee Hill.Kevinator is the official gamemaster of the Game who appears at the end of Season 4 to undo Vork ruining the in game economy by hoarding craft items and selling them for massively inflated prices. Kevinator displays a high level of narcissism over his role, proclaiming ‘I am a god!’ before shooting lightning bolts around while giggling manically. After recognising Bladezz from the Cheesy Beards commercial and becoming friends, he provides the Knights of Good with tickets for a gaming convention focused on The Game. However, in Season 5, it is revealed that Kevinator was fired from the game just before the convention for unfair play. In addition, the invite for Bladezz turns out to be a joke, as he has a habit of inviting internet memes for his boss. Kevinator is played by Simon Helberg.Rachel is one of the staff members at Megagame-o-ramacon. She is amazed with meeting Bladezz (barely able to contain her excitement when meeting him), going out of her way to help get the Guild a room. The next day, Rachel is forced to get Tink and Clara to stop selling their shirts (with the help of stormtroopers). After being stood up by Bladezz she and her friends harass him by picketing and wrecking his booth at the convention, though Bladezz does manage to apologize later. She is played by Hayley Holmes.Madeline Twain''' is a guest of Megagame-o-ramacon, an actress regarded as legendary among the fans of the convention. The former heroine of the long ago cancelled science fiction television series "Time Rings", Madeline serves as mistress of ceremonies at the con's costume contest. Vork, revealed as a former head of the star's fan club, is still smitten with her, though somewhat resentful about her abrupt exit from the series. In Season 6, Vork and Madeline begin dating. Madeline is played by Erin Gray.
ReceptionThe Guild had over 69 million upload views on YouTube as of September 2011. The series won several awards since its launch, including six Streamy Awards and four IAWTV Awards, and in February 2009, Rolling Stone named it one of "The Net's Best Serial Shows". A costume from the series has been accessioned by the National Museum of American History of the Smithsonian Institution.
In 2014 The Guild was listed on New Media Rockstars Top 100 Channels, ranked at #37.
In popular culture
Joss Whedon credits The Guild as one of the inspirations for Dr. Horrible's Sing-Along Blog, which also starred Day.
Awards and nominations
Over the course of its duration, The Guild has won and been nominated for several awards.
In other media
Comic books
On March 24, 2010, the first issue of the comic book limited series based on the show was released from Dark Horse Comics. It acts as a prequel to the show, and it was written by Felicia Day and illustrated by Jim Rugg. The second issue was released on April 23, 2010, and the third and final issue was released on May 26, 2010. The collected volume was released on November 24, 2010.
A second five-issue series was released in 2011. Each issue focuses on a single character (Vork, Zaboo, Clara, Tinkerballa, and Bladezz) and is illustrated by a different artist. The collected volume, The Guild Volume 2, was released on June 27, 2012.
An additional single character issue, The Guild: Fawkes, was issued on May 23, 2012, and takes place after season 4 of the web series.
Music videosThe Guild cast have appeared as their characters in three music videos to promote the series. In "(Do You Wanna Date My) Avatar", the cast appears as their game characters. The song and video were released shortly before the start of Season 3 and were used to promote the show. "Game On" is a Bollywood-themed video about Zaboo trying to convince Codex to play the game. This second video was used in a similar fashion and promoted Season 4. The third song and video titled "I'm the One That's Cool" is a pop rock song "touting the rise of nerd culture and the geek shall inherit the earth credo". It was released to promote the launch of Felicia Day's new YouTube channel Geek & Sundry. "(Do You Wanna Date My) Avatar" and "I'm the One That's Cool" are available on the Rock Band Network.
Production notes
Season 1The Guild was originally intended to be a pilot episode for a TV series, but Felicia Day was advised that it would be much more suited for a web series. The show changed its format and script to fit a web series. The first episode "Wake-Up Call" premiered on YouTube on July 27, 2007. After the first three episodes, the group ran out of money; but a link to Day's PayPal brought enough donations to fund "Cheesybeards" and "Rather Be Raiding". The first season ended on May 15, 2008, consisting of 10 episodes and two specials (including the Christmas special, "Christmas Raid Carol").The Guild season 1 DVD was released on Amazon.com on May 19, 2009. For Canadian audiences, it was bundled with season 2, released on September 29, 2009, also available on Amazon.com.
Season 2
Filming for season 2 began in August 2008. "Link the Loot" premiered on Xbox Live Marketplace, Microsoft Zune Marketplace, and MSN Video on November 25, 2008. Season 2 ended with "Fight!" on February 17, 2009, and featured "Love During Wartime" by The Main Drag.
On November 24, 2008, Microsoft announced an exclusive distribution deal with Guild creator Felicia Day. All twelve episodes of season 2 premiered on Xbox 360, Zune, and MSN, with a four-week delay for release on The Guilds official website. The Microsoft releases were free, but supported by Sprint advertisements and product placements.
Creator Felicia Day retains the IP rights to the series, with Microsoft paying an "unspecified" license fee upfront. Sometime in late February 2009, when all episodes of season two had been released, Day and her team were free to sign a new nonexclusive distribution deal should they choose to do so.The Guild season 2 DVD was released on Amazon.com on May 19, 2009, containing commentary tracks, gag reels, audition footage, and a "behind the scenes" documentary. It was also released for the Canadian audience along with season 1 on Amazon.com.
Season 2 was nominated for eleven Streamy Awards and won three: Best Comedy Web Series, Best Ensemble Cast in a Web Series, and Best Female Actor in a Comedy Web Series (Felicia Day).
Season 3
On August 17, 2009, a music video – "(Do You Wanna Date My) Avatar" by Felicia Day – was released on Xbox Live to promote season 3, which would premiere on August 25, 2009, on Xbox Live for members with Gold Accounts first. Later it was announced that it would be released for members with Silver Accounts, as well as Zune and MSN Video users, on September 1, 2009. The season premiered with "Expansion Time" on August 25, 2009, and ended on November 24, 2009, with "Hero". The season featured guest star Wil Wheaton as the leader of a rival guild out to destroy the Knights of Good.
Season 4
In April 2010, The Guild's official website announced the show was renewed by Microsoft for a fourth season. On June 9, 2010, the official recap of season 3—an Auto-Tuned music video by The Gregory Brothers—was posted on Bing; the video included a message that season 4 would begin on July 13, 2010.
On July 27, 2010, a second music video, called "Game On", was posted to promote season 4. On September 14, 2010, another promotional video was posted of the Cheesybeard's full commercial. Michael Chaves, director of The Curse of La Llorona, served as a visual effects artist for season 4.
Season 5
Season 5 takes place at the gaming convention mentioned at the end of season 4. Shooting began on April 21, 2011. The first episode of Season 5 was released on Xbox Live and Zune on July 26, 2011, and was released on MSN on July 28.
Season 6
Season 6 was mentioned at Comic-Con by Felicia Day. It was shot during the summer under new director Chris Preksta, creator of The Mercury Men''. It premiered on October 2, 2012, on YouTube channel Geek & Sundry.
See also
Dead Pixels
References
Further reading
External links
The Guild at Blip.TV
2000s YouTube series
2007 web series debuts
2010s YouTube series
2013 web series debuts
American comedy web series
Fictional organizations
Massively multiplayer online role-playing games in fiction
Streamy Award-winning channels, series or shows
Works about video games
Television shows adapted into comics | The Guild (web series) | Technology | 9,697 |
50,854,680 | https://en.wikipedia.org/wiki/E-aksharayan | e-Aksharayan is an optical character recognition engine for Indian languages. Some of research work from e-Aksharayan has been published in different conferences and journals.
Screenshots
References
External links
Optical character recognition
C++ software | E-aksharayan | Technology | 51 |
14,234,903 | https://en.wikipedia.org/wiki/Gynophobia | Gynophobia or gynephobia (/ˌɡaɪnəˈfoʊbiə/) is a morbid and irrational fear of women, a type of specific social phobia. It is found in ancient mythology as well as modern cases. A small number of researchers and authors have attempted to pin down possible causes of gynophobia.
Gynophobia should not generally be confused with misogyny, the hatred, contempt for and prejudice against women, although some may use the terms interchangeably, in reference to the social, rather than pathological aspect of negative attitudes towards women. The antonym of misogyny is philogyny, the love, respect for and admiration of women.
Gynophobia is analogous with androphobia, the extreme and/or irrational fear of men. A subset of it is caligynephobia, or the fear of beautiful women.
Etymology
The term gynophobia comes from the Greek γυνή – gunē, meaning "woman" and φόβος – phobos, "fear". The Oxford English Dictionary cites the term's earliest known use as an 1886 writing by physician Oliver Wendell Holmes, Sr.
Hyponyms of the term "gynophobia" include feminophobia. Rare or archaic terms include the Latin horror feminae.
Examples
In his book Sadism and Masochism: The Psychology of Hatred and Cruelty, Wilhelm Stekel discusses horror feminae of a male masochist.
Callitxe Nzamwita, an elderly Rwandan man who reported a fear of women that had persisted for more than half a century of his life, was interviewed by Afrimax in 2023. He barricaded his house to avoid interactions with women, largely remaining inside for 55 years. He was consequently cited as a possible case of gynophobia by several international media outlets, though he was never formally diagnosed.
Mythology
In ancient mythology, the idea of woman as a, "mysterious, magical body-vessel", or "intimidating Great Goddess" is common. In these myths, woman (sometimes also depicted as a Great World Tree, pomegranate, poppyhead, or mountain) bears all living things, and empties them out of herself into the living world. In the "vessel" analogy, the inside of the vessel is unknown, and all body orifices are special zones, each regarded as idols by artistic representation. The historical permanence of woman as body-vessel, is sometimes artistically depicted to elicit fear. For example, Albert Dubout depicted the Great Goddess as eliciting fear from a short man simply by displaying her large breasts and noting that her breasts survived World War II.
In India, the goddess "Kali the Terrible" is the mother of the world and a fearsome, gruesome, and bloodthirsty destroyer of human life. She partially expresses her destruction through a wide array of female avatars (or "agents"). Kali's avatars and agents are regarded by believers as responsible for serious maladies such as typhoid fever, whooping cough, epilepsy, delirium, and convulsions. For example, Kali's agent goddess Vasurimala is mythologized as responsible for smallpox and cholera. Believers in the rural Indian town of Cranganore, make symbolic monetary offerings to Kali, to fulfill promises made in fear of being stricken with smallpox or cholera.
Woman as "Great Goddess" was often depicted as a goddess of death in ancient Greek mythology as well. For example, in ancient Greek mythology, at least 7 female goddesses are depicted as both nursing mothers and as queens of the dead.
Psychology
Genitalia
Sigmund Freud, the founder of psychoanalysis, argued that male hostility towards women stemmed from a subconscious misconception of one's mother as castrated, which is then transposed onto the male individual as an irrational fear for one's own genitals. Joseph Campbell explored this in the context of a recurring image of a vagina dentata (the "toothed vagina") that envelops and then destroys the phallus, while Freud himself instead highlighted the Greek myth of Medusa as a manifestation of the fear of female genitalia and sexuality.
Karen Horney, a psychoanalytic critic of Freud's theory of castration anxiety, proposed in The Dread of Woman (1932) that gynophobia may instead be partially due to a boy's fear that his genital is inadequate in relation to the mother. She also remarked that she was surprised at the lack of explicit recognition of gynophobia, after she allegedly found ample historical, clinical, mythological, and anthropological evidence of gynophobia.
Basic resource access barriers and population expansion limitations
Extreme examples of universal, cultural gypnohobia have been found in the highlands of New Guinea, where widespread anti-masturbation propaganda coincides with notions of, "perilous female sexuality". The anthropologist Carol Ember argues that such fears were likely caused by limited availability of basic resources that would be required to increase the population.
See also
List of phobias
References
Further reading
Women in society
Phobias
Sexology
Gender-related prejudices
Misogyny | Gynophobia | Biology | 1,088 |
32,088,502 | https://en.wikipedia.org/wiki/Coxeter%20notation | In geometry, Coxeter notation (also Coxeter symbol) is a system of classifying symmetry groups, describing the angles between fundamental reflections of a Coxeter group in a bracketed notation expressing the structure of a Coxeter-Dynkin diagram, with modifiers to indicate certain subgroups. The notation is named after H. S. M. Coxeter, and has been more comprehensively defined by Norman Johnson.
Reflectional groups
For Coxeter groups, defined by pure reflections, there is a direct correspondence between the bracket notation and Coxeter-Dynkin diagram. The numbers in the bracket notation represent the mirror reflection orders in the branches of the Coxeter diagram. It uses the same simplification, suppressing 2s between orthogonal mirrors.
The Coxeter notation is simplified with exponents to represent the number of branches in a row for linear diagram. So the An group is represented by [3n−1], to imply n nodes connected by n−1 order-3 branches. Example A2 = [3,3] = [32] or [31,1] represents diagrams or .
Coxeter initially represented bifurcating diagrams with vertical positioning of numbers, but later abbreviated with an exponent notation, like [...,3p,q] or [3p,q,r], starting with [31,1,1] or [3,31,1] = or as D4. Coxeter allowed for zeros as special cases to fit the An family, like A3 = [3,3,3,3] = [34,0,0] = [34,0] = [33,1] = [32,2], like = = .
Coxeter groups formed by cyclic diagrams are represented by parentheseses inside of brackets, like [(p,q,r)] = for the triangle group (p q r). If the branch orders are equal, they can be grouped as an exponent as the length the cycle in brackets, like [(3,3,3,3)] = [3[4]], representing Coxeter diagram or . can be represented as [3,(3,3,3)] or [3,3[3]].
More complicated looping diagrams can also be expressed with care. The paracompact Coxeter group can be represented by Coxeter notation [(3,3,(3),3,3)], with nested/overlapping parentheses showing two adjacent [(3,3,3)] loops, and is also represented more compactly as [3[ ]×[ ]], representing the rhombic symmetry of the Coxeter diagram. The paracompact complete graph diagram or , is represented as [3[3,3]] with the superscript [3,3] as the symmetry of its regular tetrahedron coxeter diagram.
For the affine and hyperbolic groups, the subscript is one less than the number of nodes in each case, since each of these groups was obtained by adding a node to a finite group's diagram.
Unconnected groups
The Coxeter diagram usually leaves order-2 branches undrawn, but the bracket notation includes an explicit 2 to connect the subgraphs. So the Coxeter diagram = A2×A2 = 2A2 can be represented by [3]×[3] = [3]2 = [3,2,3]. Sometimes explicit 2-branches may be included either with a 2 label, or with a line with a gap: or , as an identical presentation as [3,2,3].
Rank and dimension
Coxeter point group rank is equal to the number of nodes which is also equal to the dimension. A single mirror exists in 1-dimension, [ ], , while in 2-dimensions [1], or [ ]×[ ]+. The 1 is a place-holder, not an actual branch order, but a marker for an orthogonal inactive mirror. The notation [n,1], represents a rank 3 group, as [n]×[ ]+ or . Similarly, [1,1] as [ ]×[ ]+×[ ]+ or order 2 and [1,1]+ as [ ]+×[ ]+×[ ]+ or , order 1!
Subgroups
Coxeter's notation represents rotational/translational symmetry by adding a + superscript operator outside the brackets, [X]+ which cuts the order of the group [X] in half, thus an index 2 subgroup. This operator implies an even number of operators must be applied, replacing reflections with rotations (or translations). When applied to a Coxeter group, this is called a direct subgroup because what remains are only direct isometries without reflective symmetry.
The + operators can also be applied inside of the brackets, like [X,Y+] or [X,(Y,Z)+], and creates "semidirect" subgroups that may include both reflective and nonreflective generators. Semidirect subgroups can only apply to Coxeter group subgroups that have even order branches adjacent to it. Elements by parentheses inside of a Coxeter group can be give a + superscript operator, having the effect of dividing adjacent ordered branches into half order, thus is usually only applied with even numbers. For example, [4,3+] and [4,(3,3)+] ().
If applied with adjacent odd branch, it doesn't create a subgroup of index 2, but instead creates overlapping fundamental domains, like [5,1+] = [5/2], which can define doubly wrapped polygons like a pentagram, {5/2}, and [5,3+] relates to Schwarz triangle [5/2,3], density 2.
Groups without neighboring + elements can be seen in ringed nodes Coxeter-Dynkin diagram for uniform polytopes and honeycomb are related to hole nodes around the + elements, empty circles with the alternated nodes removed. So the snub cube, has symmetry [4,3]+ (), and the snub tetrahedron, has symmetry [4,3+] (), and a demicube, h{4,3} = {3,3} ( or = ) has symmetry [1+,4,3] = [3,3] ( or = = ).
Note: Pyritohedral symmetry can be written as , separating the graph with gaps for clarity, with the generators {0,1,2} from the Coxeter group , producing pyritohedral generators {0,12}, a reflection and 3-fold rotation. And chiral tetrahedral symmetry can be written as or , [1+,4,3+] = [3,3]+, with generators {12,0120}.
Halving subgroups and extended groups
Johnson extends the + operator to work with a placeholder 1+ nodes, which removes mirrors, doubling the size of the fundamental domain and cuts the group order in half. In general this operation only applies to individual mirrors bounded by even-order branches. The 1 represents a mirror so [2p] can be seen as [2p,1], [1,2p], or [1,2p,1], like diagram or , with 2 mirrors related by an order-2p dihedral angle. The effect of a mirror removal is to duplicate connecting nodes, which can be seen in the Coxeter diagrams: = , or in bracket notation:[1+,2p, 1] = [1,p,1] = [p].
Each of these mirrors can be removed so h[2p] = [1+,2p,1] = [1,2p,1+] = [p], a reflective subgroup index 2. This can be shown in a Coxeter diagram by adding a + symbol above the node: = = .
If both mirrors are removed, a quarter subgroup is generated, with the branch order becoming a gyration point of half the order:
q[2p] = [1+,2p,1+] = [p]+, a rotational subgroup of index 4. = = = = .
For example, (with p=2): [4,1+] = [1+,4] = [2] = [ ]×[ ], order 4. [1+,4,1+] = [2]+, order 2.
The opposite to halving is doubling which adds a mirror, bisecting a fundamental domain, and doubling the group order.
= [2p]
Halving operations apply for higher rank groups, like tetrahedral symmetry is a half group of octahedral group: h[4,3] = [1+,4,3] = [3,3], removing half the mirrors at the 4-branch. The effect of a mirror removal is to duplicate all connecting nodes, which can be seen in the Coxeter diagrams: = , h[2p,3] = [1+,2p,3] = [(p,3,3)].
If nodes are indexed, half subgroups can be labeled with new mirrors as composites. Like , generators {0,1} has subgroup = , generators {1,010}, where mirror 0 is removed, and replaced by a copy of mirror 1 reflected across mirror 0. Also given , generators {0,1,2}, it has half group = , generators {1,2,010}.
Doubling by adding a mirror also applies in reversing the halving operation: = [4,3], or more generally = [2p,q].
Radical subgroups
Johnson also added an asterisk or star * operator for "radical" subgroups, that acts similar to the + operator, but removes rotational symmetry. The index of the radical subgroup is the order of the removed element. For example, [4,3*] ≅ [2,2]. The removed [3] subgroup is order 6 so [2,2] is an index 6 subgroup of [4,3].
The radical subgroups represent the inverse operation to an extended symmetry operation. For example, [4,3*] ≅ [2,2], and in reverse [2,2] can be extended as [3[2,2]] ≅ [4,3]. The subgroups can be expressed as a Coxeter diagram: or ≅ . The removed node (mirror) causes adjacent mirror virtual mirrors to become real mirrors.
If [4,3] has generators {0,1,2}, [4,3+], index 2, has generators {0,12}; [1+,4,3] ≅ [3,3], index 2 has generators {010,1,2}; while radical subgroup [4,3*] ≅ [2,2], index 6, has generators {01210, 2, (012)3}; and finally [1+,4,3*], index 12 has generators {0(12)20, (012)201}.
Trionic subgroups
A trionic subgroup is an index 3 subgroup. Johnson defines a trionic subgroup with operator ⅄, index 3. For rank 2 Coxeter groups, [3], the trionic subgroup, [3⅄] is [ ], a single mirror. And for [3p], the trionic subgroup is [3p]⅄ ≅ [p]. Given , with generators {0,1}, has 3 trionic subgroups. They can be differentiated by putting the ⅄ symbol next to the mirror generator to be removed, or on a branch for both: [3p,1⅄] = = , = , and [3p⅄] = = with generators {0,10101}, {01010,1}, or {101,010}.
Trionic subgroups of tetrahedral symmetry: [3,3]⅄ ≅ [2+,4], relating the symmetry of the regular tetrahedron and tetragonal disphenoid.
For rank 3 Coxeter groups, [p,3], there is a trionic subgroup [p,3⅄] ≅ [p/2,p], or = . For example, the finite group [4,3⅄] ≅ [2,4], and Euclidean group [6,3⅄] ≅ [3,6], and hyperbolic group [8,3⅄] ≅ [4,8].
An odd-order adjacent branch, p, will not lower the group order, but create overlapping fundamental domains. The group order stays the same, while the density increases. For example, the icosahedral symmetry, [5,3], of the regular polyhedra icosahedron becomes [5/2,5], the symmetry of 2 regular star polyhedra. It also relates the hyperbolic tilings {p,3}, and star hyperbolic tilings {p/2,p}
For rank 4, [q,2p,3⅄] = [2p,((p,q,q))], = .
For example, [3,4,3⅄] = [4,3,3], or = , generators {0,1,2,3} in [3,4,3] with the trionic subgroup [4,3,3] generators {0,1,2,32123}. For hyperbolic groups, [3,6,3⅄] = [6,3[3]], and [4,4,3⅄] = [4,4,4].
Trionic subgroups of tetrahedral symmetry
]
Johnson identified two specific trionic subgroups of [3,3], first an index 3 subgroup [3,3]⅄ ≅ [2+,4], with [3,3] ( = = ) generators {0,1,2}. It can also be written as [(3,3,2⅄)] () as a reminder of its generators {02,1}. This symmetry reduction is the relationship between the regular tetrahedron and the tetragonal disphenoid, represent a stretching of a tetrahedron perpendicular to two opposite edges.
Secondly he identifies a related index 6 subgroup [3,3]Δ or [(3,3,2⅄)]+ (), index 3 from [3,3]+ ≅ [2,2]+, with generators {02,1021}, from [3,3] and its generators {0,1,2}.
These subgroups also apply within larger Coxeter groups with [3,3] subgroup with neighboring branches all even order.
]
For example, [(3,3)+,4], [(3,3)⅄,4], and [(3,3)Δ,4] are subgroups of [3,3,4], index 2, 3 and 6 respectively. The generators of [(3,3)⅄,4] ≅ ≅ [8,2+,8], order 128, are {02,1,3} from [3,3,4] generators {0,1,2,3}. And [(3,3)Δ,4] ≅ , order 64, has generators {02,1021,3}. As well, [3⅄,4,3⅄] ≅ [(3,3)⅄,4].
Also related [31,1,1] = [3,3,4,1+] has trionic subgroups: [31,1,1]⅄ = [(3,3)⅄,4,1+], order 64, and 1=[31,1,1]Δ = [(3,3)Δ,4,1+] ≅ [[4,2+,4]]+, order 32.
Central inversion
A central inversion, order 2, is operationally differently by dimension. The group [ ]n = [2n−1] represents n orthogonal mirrors in n-dimensional space, or an n-flat subspace of a higher dimensional space. The mirrors of the group [2n−1] are numbered . The order of the mirrors doesn't matter in the case of an inversion. The matrix of a central inversion is , the Identity matrix with negative one on the diagonal.
From that basis, the central inversion has a generator as the product of all the orthogonal mirrors. In Coxeter notation this inversion group is expressed by adding an alternation + to each 2 branch. The alternation symmetry is marked on Coxeter diagram nodes as open nodes.
A Coxeter-Dynkin diagram can be marked up with explicit 2 branches defining a linear sequence of mirrors, open-nodes, and shared double-open nodes to show the chaining of the reflection generators.
For example, [2+,2] and [2,2+] are subgroups index 2 of [2,2], , and are represented as (or ) and (or ) with generators {01,2} and {0,12} respectively. Their common subgroup index 4 is [2+,2+], and is represented by (or ), with the double-open marking a shared node in the two alternations, and a single rotoreflection generator {012}.
Rotations and rotary reflections
Rotations and rotary reflections are constructed by a single single-generator product of all the reflections of a prismatic group, [2p]×[2q]×... where gcd(p,q,...)=1, they are isomorphic to the abstract cyclic group Zn, of order n=2pq.
The 4-dimensional double rotations, [2p+,2+,2q+] (with gcd(p,q)=1), which include a central group, and are expressed by Conway as ±[Cp×Cq], order 2pq. From Coxeter diagram , generators {0,1,2,3}, requires two generator for [2p+,2+,2q+], as {0123,0132}. Half groups, [2p+,2+,2q+]+, or cyclic graph, [(2p+,2+,2q+,2+)], expressed by Conway is [Cp×Cq], order pq, with one generator, like {0123}.
If there is a common factor f, the double rotation can be written as [2pf+,2+,2qf+] (with gcd(p,q)=1), generators {0123,0132}, order 2pqf. For example, p=q=1, f=2, [4+,2+,4+] is order 4. And [2pf+,2+,2qf+]+, generator {0123}, is order pqf. For example, [4+,2+,4+]+ is order 2, a central inversion.
In general a n-rotation group, [2p1+,2,2p2+,2,...,pn+] may require up to n generators if gcd(p1,..,pn)>1, as a product of all mirrors, and then swapping sequential pairs. The half group, [2p1+,2,2p2+,2,...,pn+]+ has generators squared. n-rotary reflections are similar.
Commutator subgroups
Simple groups with only odd-order branch elements have only a single rotational/translational subgroup of order 2, which is also the commutator subgroup, examples [3,3]+, [3,5]+, [3,3,3]+, [3,3,5]+. For other Coxeter groups with even-order branches, the commutator subgroup has index 2c, where c is the number of disconnected subgraphs when all the even-order branches are removed.
For example, [4,4] has three independent nodes in the Coxeter diagram when the 4s are removed, so its commutator subgroup is index 23, and can have different representations, all with three + operators: [4+,4+]+, [1+,4,1+,4,1+], [1+,4,4,1+]+, or [(4+,4+,2+)]. A general notation can be used with +c as a group exponent, like [4,4]+3.
Example subgroups
Rank 2 example subgroups
Dihedral symmetry groups with even-orders have a number of subgroups. This example shows two generator mirrors of [4] in red and green, and looks at all subgroups by halfing, rank-reduction, and their direct subgroups. The group [4], has two mirror generators 0, and 1. Each generate two virtual mirrors 101 and 010 by reflection across the other.
Rank 3 Euclidean example subgroups
The [4,4] group has 15 small index subgroups. This table shows them all, with a yellow fundamental domain for pure reflective groups, and alternating white and blue domains which are paired up to make rotational domains. Cyan, red, and green mirror lines correspond to the same colored nodes in the Coxeter diagram. Subgroup generators can be expressed as products of the original 3 mirrors of the fundamental domain, {0,1,2}, corresponding to the 3 nodes of the Coxeter diagram, . A product of two intersecting reflection lines makes a rotation, like {012}, {12}, or {02}. Removing a mirror causes two copies of neighboring mirrors, across the removed mirror, like {010}, and {212}. Two rotations in series cut the rotation order in half, like {0101} or {(01)2}, {1212} or {(02)2}. A product of all three mirrors creates a transreflection, like {012} or {120}.
Hyperbolic example subgroups
The same set of 15 small subgroups exists on all triangle groups with even order elements, like [6,4] in the hyperbolic plane:
Parabolic subgroups
A parabolic subgroup of a Coxeter group can be identified by removing one or more generator mirrors represented with a Coxeter diagram. For example the octahedral group has parabolic subgroups , , , , , . In bracket notation [4,3] has parabolic subgroups [4],[2],[3], and a single mirror []. The order of the subgroup is known, and always an integer divisor group order, or index. Parabolic subgroups can also be written with x nodes, like =[4,3] subgroup by removing second mirror: or = = [4,1×,3] = [2].
Petrie subgroup
A petrie subgroup of an irreducible coxeter group can be created by the product of all of the generators. It can be seen in the skew regular petrie polygon of a regular polytope. The order of the new group is called the Coxeter number of the original Coxeter group. The Coxeter number of a Coxeter group is 2m/n, where n is the rank, and m is the number of reflections. A petrie subgroup can be written with a superscript. For example, [3,3] is the petrie subgroup of a tetrahedral group, cyclic group order 4, generated by a rotoreflection. A rank 4 Coxeter group will have a double rotation generator, like [4,3,3] is order 8.
Extended symmetry
Coxeter's notation includes double square bracket notation, to express automorphic symmetry within a Coxeter diagram. Johnson added alternative doubling by angled-bracket <[X]>. Johnson also added a prefix symmetry modifier [Y[X]], where Y can either represent symmetry of the Coxeter diagram of [X], or symmetry of the fundamental domain of [X].
For example, in 3D these equivalent rectangle and rhombic geometry diagrams of : and , the first doubled with square brackets, or twice doubled as [2[3[4]]], with [2], order 4 higher symmetry. To differentiate the second, angled brackets are used for doubling, <[3[4]]> and twice doubled as <2[3[4]]>, also with a different [2], order 4 symmetry. Finally a full symmetry where all 4 nodes are equivalent can be represented by [4[3[4]]], with the order 8, [4] symmetry of the square. But by considering the tetragonal disphenoid fundamental domain the [4] extended symmetry of the square graph can be marked more explicitly as [(2+,4)[3[4]]] or [2+,4[3[4]]].
Further symmetry exists in the cyclic and branching , , and diagrams. has order 2n symmetry of a regular n-gon, {n}, and is represented by [n[3[n]]]. and are represented by [3[31,1,1]] = [3,4,3] and [3[32,2,2]] respectively while by [(3,3)[31,1,1,1]] = [3,3,4,3], with the diagram containing the order 24 symmetry of the regular tetrahedron, {3,3}. The paracompact hyperbolic group = [31,1,1,1,1], , contains the symmetry of a 5-cell, {3,3,3}, and thus is represented by [(3,3,3)[31,1,1,1,1]] = [3,4,3,3,3].
An asterisk * superscript is effectively an inverse operation, creating radical subgroups removing connected of odd-ordered mirrors.
Examples:
Looking at generators, the double symmetry is seen as adding a new operator that maps symmetric positions in the Coxeter diagram, making some original generators redundant. For 3D space groups, and 4D point groups, Coxeter defines an index two subgroup of , , which he defines as the product of the original generators of [X] by the doubling generator. This looks similar to +, which is the chiral subgroup of . So for example the 3D space groups + (I432, 211) and (Pmn,
223) are distinct subgroups of (Imm, 229).
Rank one groups
In one dimension, the bilateral group [ ] represents a single mirror symmetry, abstract Dih1 or Z2, symmetry order 2. It is represented as a Coxeter–Dynkin diagram with a single node, . The identity group is the direct subgroup [ ]+, Z1, symmetry order 1. The + superscript simply implies that alternate mirror reflections are ignored, leaving the identity group in this simplest case. Coxeter used a single open node to represent an alternation, .
Rank two groups
In two dimensions, the rectangular group [2], abstract D22 or D4, also can be represented as a direct product [ ]×[ ], being the product of two bilateral groups, represents two orthogonal mirrors, with Coxeter diagram, , with order 4. The 2 in [2] comes from linearization of the orthogonal subgraphs in the Coxeter diagram, as with explicit branch order 2. The rhombic group, [2]+ ( or ), half of the rectangular group, the point reflection symmetry, Z2, order 2.
Coxeter notation to allow a 1 place-holder for lower rank groups, so [1] is the same as [ ], and [1+] or [1]+ is the same as [ ]+ and Coxeter diagram .
The full p-gonal group [p], abstract dihedral group D2p, (nonabelian for p>2), of order 2p, is generated by two mirrors at angle π/p, represented by Coxeter diagram . The p-gonal subgroup [p]+, cyclic group Zp, of order p, generated by a rotation angle of π/p.
Coxeter notation uses double-bracking to represent an automorphic doubling of symmetry by adding a bisecting mirror to the fundamental domain. For example, [[p]] adds a bisecting mirror to [p], and is isomorphic to [2p].
In the limit, going down to one dimensions, the full apeirogonal group is obtained when the angle goes to zero, so [∞], abstractly the infinite dihedral group D∞, represents two parallel mirrors and has a Coxeter diagram . The apeirogonal group [∞]+, , abstractly the infinite cyclic group Z∞, isomorphic to the additive group of the integers, is generated by a single nonzero translation.
In the hyperbolic plane, there is a full pseudogonal group [iπ/λ], and pseudogonal subgroup [iπ/λ]+, . These groups exist in regular infinite-sided polygons, with edge length λ. The mirrors are all orthogonal to a single line.
Rank three groups
Point groups in 3 dimensions can be expressed in bracket notation related to the rank 3 Coxeter groups:
In three dimensions, the full orthorhombic group or orthorectangular [2,2], abstractly Z23, order 8, represents three orthogonal mirrors, (also represented by Coxeter diagram as three separate dots ). It can also can be represented as a direct product [ ]×[ ]×[ ], but the [2,2] expression allows subgroups to be defined:
First there is a "semidirect" subgroup, the orthorhombic group, [2,2+] ( or ), abstractly Z2×Z2, of order 4. When the + superscript is given inside of the brackets, it means reflections generated only from the adjacent mirrors (as defined by the Coxeter diagram, ) are alternated. In general, the branch orders neighboring the + node must be even. In this case [2,2+] and [2+,2] represent two isomorphic subgroups that are geometrically distinct. The other subgroups are the pararhombic group [2,2]+ ( or ), also order 4, and finally the central group [2+,2+] ( or ) of order 2.
Next there is the full ortho-p-gonal group, [2,p] (), abstractly Z2×D2p, of order 4p, representing two mirrors at a dihedral angle π/p, and both are orthogonal to a third mirror. It is also represented by Coxeter diagram as .
The direct subgroup is called the para-p-gonal group, [2,p]+ ( or ), abstractly D2p, of order 2p, and another subgroup is [2,p+] () abstractly Z2×Zp, also of order 2p.
The full gyro-p-gonal group, [2+,2p] ( or ), abstractly D4p, of order 4p. The gyro-p-gonal group, [2+,2p+] ( or ), abstractly Z2p, of order 2p is a subgroup of both [2+,2p] and [2,2p+].
The polyhedral groups are based on the symmetry of platonic solids: the tetrahedron, octahedron, cube, icosahedron, and dodecahedron, with Schläfli symbols {3,3}, {3,4}, {4,3}, {3,5}, and {5,3} respectively. The Coxeter groups for these are: [3,3] (), [3,4] (), [3,5] () called full tetrahedral symmetry, octahedral symmetry, and icosahedral symmetry, with orders of 24, 48, and 120.
In all these symmetries, alternate reflections can be removed producing the rotational tetrahedral [3,3]+(), octahedral [3,4]+ (), and icosahedral [3,5]+ () groups of order 12, 24, and 60. The octahedral group also has a unique index 2 subgroup called the pyritohedral symmetry group, [3+,4] ( or ), of order 12, with a mixture of rotational and reflectional symmetry. Pyritohedral symmetry is also an index 5 subgroup of icosahedral symmetry: --> , with virtual mirror 1 across 0, {010}, and 3-fold rotation {12}.
The tetrahedral group, [3,3] (), has a doubling (which can be represented by colored nodes ), mapping the first and last mirrors onto each other, and this produces the [3,4] ( or ) group. The subgroup [3,4,1+] ( or ) is the same as [3,3], and [3+,4,1+] ( or ) is the same as [3,3]+.
Affine
In the Euclidean plane there's 3 fundamental reflective groups generated by 3 mirrors, represented by Coxeter diagrams , , and , and are given Coxeter notation as [4,4], [6,3], and [(3,3,3)]. The parentheses of the last group imply the diagram cycle, and also has a shorthand notation [3[3]].
as a doubling of the [4,4] group produced the same symmetry rotated π/4 from the original set of mirrors.
Direct subgroups of rotational symmetry are: [4,4]+, [6,3]+, and [(3,3,3)]+. [4+,4] and [6,3+] are semidirect subgroups.
Given in Coxeter notation (orbifold notation), some low index affine subgroups are:
Rank four groups
Point groups
Rank four groups defined the 4-dimensional point groups:
Subgroups
Space groups
Line groups
Rank four groups also defined the 3-dimensional line groups:
Duoprismatic group
Rank four groups defined the 4-dimensional duoprismatic groups. In the limit as p and q go to infinity, they degenerate into 2 dimensions and the wallpaper groups.
Wallpaper groups
Rank four groups also defined some of the 2-dimensional wallpaper groups, as limiting cases of the four-dimensional duoprism groups:
Subgroups of [∞,2,∞], (*2222) can be expressed down to its index 16 commutator subgroup:
Complex reflections
Coxeter notation has been extended to Complex space, Cn where nodes are unitary reflections of period 2 or greater. Nodes are labeled by an index, assumed to be 2 for ordinary real reflection if suppressed. Complex reflection groups are called Shephard groups rather than Coxeter groups, and can be used to construct complex polytopes.
In , a rank 1 Shephard group , order p, is represented as p[ ], [ ]p or ]p[. It has a single generator, representing a 2π/p radian rotation in the Complex plane: .
Coxeter writes the rank 2 complex group, p[q]r represents Coxeter diagram . The p and r should only be suppressed if both are 2, which is the real case [q]. The order of a rank 2 group p[q]r is .
The rank 2 solutions that generate complex polygons are: p[4]2 (p is 2,3,4,...), 3[3]3, 3[6]2, 3[4]3, 4[3]4, 3[8]2, 4[6]2, 4[4]3, 3[5]3, 5[3]5, 3[10]2, 5[6]2, and 5[4]3 with Coxeter diagrams , , , , , , , , , , , , .
Infinite groups are 3[12]2, 4[8]2, 6[6]2, 3[6]3, 6[4]3, 4[4]4, and 6[3]6 or , , , , , , .
Index 2 subgroups exists by removing a real reflection: p[2q]2 → p[q]p. Also index r subgroups exist for 4 branches: p[4]r → p[r]p.
For the infinite family p[4]2, for any p = 2, 3, 4,..., there are two subgroups: p[4]2 → [p], index p, while and p[4]2 → p[ ]×p[ ], index 2.
Computation with reflection matrices as symmetry generators
A Coxeter group, represented by Coxeter diagram , is given Coxeter notation [p,q] for the branch orders. Each node in the Coxeter diagram represents a mirror, by convention called ρi (and matrix Ri). The generators of this group [p,q] are reflections: ρ0, ρ1, and ρ2. Rotational subsymmetry is given as products of reflections: By convention, σ0,1 (and matrix S0,1) = ρ0ρ1 represents a rotation of angle π/p, and σ1,2 = ρ1ρ2 is a rotation of angle π/q, and σ0,2 = ρ0ρ2 represents a rotation of angle π/2.
[p,q]+, , is an index 2 subgroup represented by two rotation generators, each a products of two reflections: σ0,1, σ1,2, and representing rotations of π/p, and π/q angles respectively.
With one even branch, [p+,2q], or , is another subgroup of index 2, represented by rotation generator σ0,1, and reflectional ρ2.
With even branches, [2p+,2q+], , is a subgroup of index 4 with two generators, constructed as a product of all three reflection matrices: By convention as: ψ0,1,2 and ψ1,2,0, which are rotary reflections, representing a reflection and rotation or reflection.
In the case of affine Coxeter groups like , or , one mirror, usually the last, is translated off the origin. A translation generator τ0,1 (and matrix T0,1) is constructed as the product of two (or an even number of) reflections, including the affine reflection. A transreflection (reflection plus a translation) can be the product of an odd number of reflections φ0,1,2 (and matrix V0,1,2), like the index 4 subgroup : [4+,4+] = .
Another composite generator, by convention as ζ (and matrix Z), represents the inversion, mapping a point to its inverse. For [4,3] and [5,3], ζ = (ρ0ρ1ρ2)h/2, where h is 6 and 10 respectively, the Coxeter number for each family. For 3D Coxeter group [p,q] (), this subgroup is a rotary reflection [2+,h+].
Coxeter groups are categorized by their rank, being the number of nodes in its Coxeter-Dynkin diagram. The structure of the groups are also given with their abstract group types: In this article, the abstract dihedral groups are represented as Dihn, and cyclic groups are represented by Zn, with Dih1=Z2.
Rank 2
Example, in 2D, the Coxeter group [p] () is represented by two reflection matrices R0 and R1, The cyclic symmetry [p]+ () is represented by rotation generator of matrix S0,1.
Rank 3
The finite rank 3 Coxeter groups are [1,p], [2,p], [3,3], [3,4], and [3,5].
To reflect a point through a plane (which goes through the origin), one can use , where is the 3×3 identity matrix and is the three-dimensional unit vector for the vector normal of the plane. If the L2 norm of and is unity, the transformation matrix can be expressed as:
[p,2]
The reducible 3-dimensional finite reflective group is dihedral symmetry, [p,2], order 4p, . The reflection generators are matrices R0, R1, R2. R02=R12=R22=(R0×R1)3=(R1×R2)3=(R0×R2)2=Identity. [p,2]+ () is generated by 2 of 3 rotations: S0,1, S1,2, and S0,2. An order p rotoreflection is generated by V0,1,2, the product of all 3 reflections.
[3,3]
The simplest irreducible 3-dimensional finite reflective group is tetrahedral symmetry, [3,3], order 24, . The reflection generators, from a D3=A3 construction, are matrices R0, R1, R2. R02=R12=R22=(R0×R1)3=(R1×R2)3=(R0×R2)2=Identity. [3,3]+ () is generated by 2 of 3 rotations: S0,1, S1,2, and S0,2. A trionic subgroup, isomorphic to [2+,4], order 8, is generated by S0,2 and R1. An order 4 rotoreflection is generated by V0,1,2, the product of all 3 reflections.
[4,3]
Another irreducible 3-dimensional finite reflective group is octahedral symmetry, [4,3], order 48, . The reflection generators matrices are R0, R1, R2. R02=R12=R22=(R0×R1)4=(R1×R2)3=(R0×R2)2=Identity. Chiral octahedral symmetry, [4,3]+, () is generated by 2 of 3 rotations: S0,1, S1,2, and S0,2. Pyritohedral symmetry [4,3+], () is generated by reflection R0 and rotation S1,2. A 6-fold rotoreflection is generated by V0,1,2, the product of all 3 reflections.
[5,3]
A final irreducible 3-dimensional finite reflective group is icosahedral symmetry, [5,3], order 120, . The reflection generators matrices are R0, R1, R2. R02=R12=R22=(R0×R1)5=(R1×R2)3=(R0×R2)2=Identity. [5,3]+ () is generated by 2 of 3 rotations: S0,1, S1,2, and S0,2. A 10-fold rotoreflection is generated by V0,1,2, the product of all 3 reflections.
Rank 4
There are 4 irreducible Coxeter groups in 4 dimensions: [3,3,3], [4,3,3], [31,1,1], [3,4,4], [5,3,3], as well as an infinite family of duoprismatic groups [p,2,q].
[p,2,q]
The duprismatic group, [p,2,q], has order 4pq.
[[p,2,p]]
The duoprismatic group can double in order, to 8p2, with a 2-fold rotation between the two planes.
[3,3,3]
Hypertetrahedral symmetry, [3,3,3], order 120, is easiest to represent with 4 mirrors in 5-dimensions, as a subgroup of [4,3,3,3].
[[3,3,3]]
The extended group [[3,3,3]], order 240, is doubled by a 2-fold rotation matrix T, here reversing coordinate order and sign: There are 3 generators {T, R0, R1}. Since T is self-reciprocal R3=TR0T, and R2=TR1T.
[4,3,3]
A irreducible 4-dimensional finite reflective group is hyperoctahedral group (or hexadecachoric group (for 16-cell), B4=[4,3,3], order 384, . The reflection generators matrices are R0, R1, R2, R3. R02=R12=R22=R32=(R0×R1)4=(R1×R2)3=(R2×R3)3=(R0×R2)2=(R1×R3)2=(R0×R3)2=Identity.
Chiral hyperoctahedral symmetry, [4,3,3]+, () is generated by 3 of 6 rotations: S0,1, S1,2, S2,3, S0,2, S1,3, and S0,3. Hyperpyritohedral symmetry [4,(3,3)+], () is generated by reflection R0 and rotations S1,2 and S2,3. An 8-fold double rotation is generated by W0,1,2,3, the product of all 4 reflections.
[3,31,1]
A half group of [4,3,3] is [3,31,1], , order 192. It shares 3 generators with [4,3,3] group, but has two copies of an adjacent generator, one reflected across the removed mirror.
[3,4,3]
A irreducible 4-dimensional finite reflective group is Icositetrachoric group (for 24-cell), F4=[3,4,3], order 1152, . The reflection generators matrices are R0, R1, R2, R3. R02=R12=R22=R32=(R0×R1)3=(R1×R2)4=(R2×R3)3=(R0×R2)2=(R1×R3)2=(R0×R3)2=Identity.
Chiral icositetrachoric symmetry, [3,4,3]+, () is generated by 3 of 6 rotations: S0,1, S1,2, S2,3, S0,2, S1,3, and S0,3. Ionic diminished [3,4,3+] group, () is generated by reflection R0 and rotations S1,2 and S2,3. A 12-fold double rotation is generated by W0,1,2,3, the product of all 4 reflections.
[[3,4,3]]
The group [[3,4,3]] extends [3,4,3] by a 2-fold rotation, T, doubling order to 2304.
[5,3,3]
The hyper-icosahedral symmetry, [5,3,3], order 14400, . The reflection generators matrices are R0, R1, R2, R3. R02=R12=R22=R32=(R0×R1)5=(R1×R2)3=(R2×R3)3=(R0×R2)2=(R0×R3)2=(R1×R3)2=Identity. [5,3,3]+ () is generated by 3 rotations: S0,1 = R0×R1, S1,2 = R1×R2, S2,3 = R2×R3, etc.
Rank 8
[34,2,1]
The E8 Coxeter group, [34,2,1], , has 8 mirror nodes, order 696729600 (192x10!). E7 and E6, [33,2,1], , and [32,2,1], can be constructed by ignoring the first mirror or the first two mirrors respectively.
Affine rank 2
Affine matrices are represented by adding an extra row and column, the last row being zero except last entry 1. The last column represents a translation vector.
[∞]
The affine group [∞], , can be given by two reflection matrices, x=0 and x=1.
Affine rank 3
[4,4]
The affine group [4,4], , (p4m), can be given by three reflection matrices, reflections across the x axis (y=0), a diagonal (x=y), and the affine reflection across the line (x=1). [4,4]+ () (p4) is generated by S0,1 S1,2, and S0,2. [4+,4+] () (pgg) is generated by 2-fold rotation S0,2 and glide reflection (transreflection) V0,1,2. [4+,4] () (p4g) is generated by S0,1 and R3. The group [(4,4,2+)] () (cmm), is generated by 2-fold rotation S1,3 and reflection R2.
[3,6]
The affine group [3,6], , (p6m), can be given by three reflection matrices, reflections across the x axis (y=0), line y=(√3/2)x, and vertical line x=1.
[3[3]]
The affine group [3[3]] can be constructed as a half group of . R2 is replaced by R'2 = R2×R1×R2, presented by the hyperplane: y+(√3/2)x=2. The fundamental domain is an equilateral triangle with edge length 2.
Affine rank 4
[4,3,4]
The affine group is [4,3,4] (), can be given by four reflection matrices. Mirror R0 can be put on z=0 plane. Mirror R1 can be put on plane y=z. Mirror R2 can be put on x=y plane. Mirror R3 can be put on x=1 plane. [4,3,4]+ () is generated by S0,1, S1,2, and S2,3.
[[4,3,4]]
The extended group [[4,3,4]] doubles the group order, adding with a 2-fold rotation matrix T, with a fixed axis through points (1,1/2,0) and (1/2,1/2,1/2). The generators are {R0,R1,T}. R2 = T×R1×T and R3 = T×R0×T.
[4,31,1]
The group [4,31,1] can be constructed from [4,3,4], by computing [4,3,4,1+], , as R'3=R3×R2×R3, with new R'3 as an image of R2 across R3.
[3[4]]
The group [3[4]] can be constructed from [4,3,4], by removing first and last mirrors, [1+,4,3,4,1+], , by R'1=R0×R1×R0 and R'3=R3×R2×R3.
Notes
References
H.S.M. Coxeter:
Kaleidoscopes: Selected Writings of H.S.M. Coxeter, editied by F. Arthur Sherk, Peter McMullen, Anthony C. Thompson, Asia Ivic Weiss, Wiley-Interscience Publication, 1995,
(Paper 22)
(Paper 23)
(Paper 24)
Norman Johnson Uniform Polytopes, Manuscript (1991)
N.W. Johnson: The Theory of Uniform Polytopes and Honeycombs, Ph.D. (1966)
Norman W. Johnson and Asia Ivic Weiss Quadratic Integers and Coxeter Groups PDF Can. J. Math. Vol. 51 (6), 1999 pp. 1307–1336
N. W. Johnson: Geometries and Transformations, (2018) PDF
John H. Conway and Derek A. Smith, On Quaternions and Octonions, 2003,
The Symmetries of Things 2008, John H. Conway, Heidi Burgiel, Chaim Goodman-Strauss, Ch.22 35 prime space groups, ch.25 184 composite space groups, ch.26 Higher still, 4D point groups
Symmetry
Group theory | Coxeter notation | Physics,Mathematics | 11,332 |
406,726 | https://en.wikipedia.org/wiki/Toll-free%20telephone%20number | A toll-free telephone number or freephone number is one number that is billed for all arriving calls. For the calling party, a call to a toll-free number from a landline is free of charge. A toll-free number is identified by a dialing prefix similar to an area code. The specific service access varies by country.
History
The features of toll-free services have evolved as telephone networks have evolved from electro-mechanical call switching to computerized stored program controlled networks.
Originally, before the automatic system was developed, a call billed to the called party had to be placed through a telephone company operator as a collect call, often long-distance. The operator had to secure acceptance of the charges at the remote number, or even transfer that decision to a long-distance operator, before manually completing the call.
Some large businesses and government offices received large numbers of collect calls, which proved time-consuming for operators and the callers.
Manual toll-free systems
Prior to the development of customer-dialed toll-free service many telephone companies provided the service by operator assistance for telephone subscribers without dial telephones (manual service).
Operator-assisted toll-free calling included the Zenith number service introduced in the 1930s in the U.S. and Canada, as well as the manual 'Freephone' service introduced by the British Post Office in 1960.
Both systems were similar in concept. The calling party would ring the operator (now '100' in the UK, '0' in Canada/U.S.) and ask for a specific free number. In the U.S., the caller would ask for a number like "Zenith 12345" (some areas used "Enterprise" or "WX" instead of "Zenith"). In the UK, the caller would ask the operator to ring "Freephone" and a name or number (such as "Freephone Crimebusters" to pass on tips about a crime to the constabulary).
In either case, the operator would look up the corresponding geographic number from a list and place the call with charges reversed.
A Zenith number was typically available from a predefined area, anything from a few nearby cities to a province or state, and was listed in local directories in each community from which the subscriber was willing to accept the charges for inbound calls.
Until the introduction of InWATS toll-free service by the Bell System on May 2, 1967 and the Linkline (later "Freefone") 0800 services by British Telecom on 12 November 1985, manually ringing the operator was the standard means to place a toll-free call. More than a few established manual "Freephone" or "Zenith" numbers remained in use for many years after competing automated systems (0800 in UK, 1800 in U.S.) were deployed in parallel for new toll-free numbers.
Initial direct-dial systems
An automated toll-free service was introduced by AT&T in 1966 (US intrastate) and 1967 (US interstate) as an alternative to operator-assisted collect calling and manual "Zenith" or "Enterprise" numbers. This Inward Wide Area Telephone Service (InWATS) allowed calls to be made directly from anywhere in a predefined area by dialling the prefix 1800- and a seven-digit number.
The system initially provided no support for Automatic Number Identification and no itemised record of calls, instead requiring subscribers to obtain expensive fixed-rate lines which included some number of hours of inbound calling from a "band" of one or several U.S. states or Canadian provinces. Early InWATS 800 calling lacked the complex routing features offered with modern toll-free service. After competitive carriers were allowed to compete with AT&T in establishing toll-free service, the three digit exchange following the 800 prefix was linked to a specific destination carrier and area code; the number itself corresponded to specific telephone switching offices and trunk groups. All calls went to one central destination; there was no means to place a toll-free call to another country.
Despite its limitations (and the relatively high cost of long distance in that era), the system was adequate for the needs of large volume users such as hotel chains, airlines and rental car firms which used it to build a truly national presence.
For small regional businesses who received few long-distance calls, the original InWATS was prohibitively expensive. As a fixed-rate bulk service requiring special trunks, it was suited only to large volume users.
Modern direct-dial systems
Modern toll-free service became possible when telephone companies replaced their electro-mechanical switching systems with computerized switching systems. This allowed toll-free calls to be routed based on instructions located in central databases.
In the United States, AT&T engineer Roy P. Weber from Bridgewater, New Jersey patented a 'Data Base Communication Call Processing Method' which was deployed by AT&T in 1982. The called number was an index into a database, allowing a 'Toll-Free Call' or '800 Call' to be directed anywhere. This feature and other advances that made it possible were what led to AT&T marketing analyst Dodge Cepeda from Bedminster, New Jersey to propose the introduction of providing 800 Toll-Free Service to small and medium-size business customers on a nationwide basis. Once this service was implemented, it became possible for the very smallest of business operations to have potential customers contact them free of charge at a time when long-distance calling was expensive. Until this time, 800 Service was only available to major Fortune 500 companies.
In the United Kingdom, BT introduced "Linkline" on 12 November 1985. No more need to manually ring the operator, two new prefixes 0800 (an automated toll-free service which became "Freefone") and 0345 (a shared-cost service marketed as "Lo-Call" because initially its rates resembled those of local calls) could be reached by direct dial. Cable and Wireless used 0500 and 0645, in much the same way, just a few years later.
Vanity numbering
A toll-free vanity number, custom toll-free number, or mnemonic is easy to remember; it spells and means something or it contains an easily recognized numeric pattern. An easily remembered number is valued as a branding and direct response tool in business advertising.
In the United States, Federal Communications Commission regulations mandate that numbers be allocated on a first come, first served basis; this gives vanity number operators who register as RespOrgs a strong advantage in obtaining the most valuable phonewords, as they have first access to newly disconnected numbers and to newly introduced toll-free area codes. In Australia, premium numbers, such as the 13-series or the vanity phone words, are distributed by auction separately from the administrative procedure to assign random, generic numbers from the available pool.
Shared use
In toll-free telephony, a shared-use number is a vanity number (usually a valuable generic phone word), which is rented to multiple local companies in the same line of business in different cities. These appear in Australia (1300 and 1800) and North America (1800, etc.); in the U.S., the RespOrg infrastructure is used to direct calls for the same number to different vendors based on the area code of the calling number.
As one example, a taxi company could rent shared use of 1800TAXICAB in one city. The number belongs to a company in Van Nuys, California, but is redirected to local cab companies on a city-by-city basis and promoted by being printed on everything from individual taxi cab hub caps to campaigns against drunk driving. Another example is Mark Russell's 1800GREATRATE, a shared-use number rented to lenders in various cities nationwide for a monthly fee.
One former Mercedes dealer obtained 1800MERCEDES, charging other dealers to receive calls to that number from their local areas. The automaker unsuccessfully sued MBZ Communications of Owatonna, Minnesota, operated by former Mercedes dealer Donald Bloom, alleging deception and trademark infringement. Mercedes was ultimately forced to obtain a different number, 1-800-FOR-MERCEDES.
A company renting 1800REDCROSS at a premium price to individual local Red Cross chapters as "shared use" was less fortunate; the Federal Communications Commission reassigned that number to the American Red Cross as an emergency response to Hurricane Katrina in 2005.
Shared use can be used as a means to circumvent FCC regulations against "warehousing, hoarding and brokering" toll-free numbers as technically the number is not being sold, only rented one city or region at a time. The practice is nonetheless potentially problematic as it leaves local businesses advertising numbers which they do not own and for which they therefore have no number portability. The cost per minute and per month is typically far higher for a shared-use number than for a standard toll-free vanity number which a local business controls outright, and there is little protection if the shared use company fails to meet its obligations or ceases operation.
There are also technical limitations; voice over IP users in particular are difficult to geolocate as their calls may be gated to the public switched telephone network at a point hundreds or thousands of miles away from their actual location. A roaming mobile or Internet telephone user is effectively (like the user of a foreign exchange line) attached to a distant rate centre far from their physical address.
If a program like Crime Stoppers is inherently regional or local, but its national 1800222TIPS number is shared between multiple exchanges, the exchange accepting the call must determine whether the call belongs to some other region.
International implementations
The implementation of toll-free calling by assigning special telephone numbers for charging a destination party is implemented in many countries by various dialing prefixes in the local number plan.
In Argentina, the prefix for toll-free numbers is "0800", followed by seven digits (the first three of them are fixed for each operator, so the user may know which carrier is serving the party they are calling). These numbers are called "0800" (cero ochocientos) or líneas gratuitas (free lines). There is also a local-rate service named "0-810" (cero ochocientos diez) where the calling party pays the fee for a local call and the called party pays for the long-distance fees.
In Armenia, the toll-free prefix is "800" followed by a five-digit number.
In Australia, the toll-free prefix is "1800" followed by a six-digit number. Calls are free from any landline and generally free from mobiles, although some mobile providers may charge their own fee. A fixed-cost fee (usually the cost of a local call) is payable by the caller to "1300" and "13" prefix numbers (followed by six and four digits respectively).
In Austria, the prefix for toll-free numbers is also "0800", but only followed by six digits. They are commonly referred to as null-achthunderter Nummern (zero-eight hundred numbers).
In Azerbaijan, the prefix for toll -free numbers is 088, followed with seven digits. Toll Free calls are available both from mobile and landline phone operators.
In Belgium, the prefix "0800" is used for toll-free numbers, followed by 5 digits. They are commonly referred to as nul-achthonderd nummers (zero-eight hundred numbers) in Dutch, numéros verts (green numbers) in French or "null-achthunderter Nummern" (zero-eight hundred numbers) in the German speaking area.
In Brazil, the toll-free prefix is "0800". Although regular landline numbers in Brazil are 8 digits long, the toll-free prefix is usually followed by 7 digits, with 6 digits formerly common. Toll-free numbers in Brazil can be accessed from any telephone (by default) within the country, with many exceptions. They can only be accessed from outside Brazil by using a calling service (such as voice-over-Internet services or MCI Worldcom calling service) that accesses numbers from within the called country. Many toll-free numbers are not available from cell phones (usually blocked by the cell phone provider rather than by the provider of the toll-free number, in an effort to prevent low-price competition from calling card providers). Some toll-free numbers are not available from phones listed by the owner of the number, including many payphones. There is no special name for the service and when such a number is advertised, there is usually a remark that the call is free.
In Bulgaria, the toll-free prefix is "0800" followed by a five-digit number (up to now, only 1XXXX and 20ххх numbers have been allocated). These numbers are called Зелен номер (green number) by Vivacom and Зелена линия (green line) by A1.
In Canada, toll-free numbers are drawn from the US SMS/800 database. A seven-digit number 310-xxxx (a true toll-free, can be called from anywhere in its home area code at local rates from certain, but not all, carriers) is available in Bell Canada and Telus territories. From a landline, these are free. From cell phones, airtime is not covered, but there are no long-distance charges.
In Chile, the toll-free prefix is "800" followed by a six-digit number. These numbers are called número 800 (800 number). These numbers cannot be accessed from abroad.
In Colombia, toll-free numbers start with "018000".
In Croatia, the prefix for toll-free numbers is "0800".
In the Czech Republic, the toll-free prefix is "800".
In Denmark telephone-numbers have eight digits. The toll-free numbers all begin with "80" followed by six further digits.
The Dominican Republic is assigned specific 1800 exchanges in the North American Numbering Plan; the 1-809-200-xxxx exchange is also free for domestic callers in that country.
In Egypt, it starts with "0800" followed by a seven-digit number. Unavailable via cellphones.
In Ecuador, it starts with "1800" followed by a 6-digit number. Some numbers have either regional or nationwide access. Calls from cellphones are only allowed by the operator Alegro which charges a few cents for these calls. PORTA and Movistar do not allow the service.
In France the "0800" to "0805" prefixes are used for toll-free numbers. They are also known as numéros verts (green numbers).
In Finland, the toll-free prefix is "0800".
In Germany, the toll-free prefix is "'0800" followed by a seven-digit number. The "0801" prefix is already reserved for future use. The prefix used to be "0130". Deutsche Telekom calls these numbers "freecall 0800", most Germans refer to it simply as null-achthunderter Nummern (zero-eight hundred numbers).
In Georgia, the prefix for toll-free numbers is 0800 followed with six digits. Toll-free calls are available both from mobile and landline phone operators.
In Greece, the toll-free prefix is "800" followed by a seven-digit number or "807" followed by a four-digit number, used for phone card services only.
In Hong Kong, toll-free numbers have the "800" prefix.
In Hungary, toll-free numbers have the "80" prefix.
In Iceland, the toll-free prefix is "800", followed by a four-digit number.
In India, the toll-free prefix is "1800", followed by a six or seven digit number. They are free of charge if called from a mobile phone or a land line. The "1860" prefix followed by seven digits is used for local-rate numbers. The calling party pays the local rate and the called party pays long-distance call charges (if any).
In Indonesia, the toll-free prefix is "0800-1", followed by a six-digit number.
In Ireland, 1800- numbers are freephones, with the 1800 71xxxx reserved for services that expect unusually high volumes of calls (e.g. radio station phone-in lines).
In Israel, toll-free numbers are prefixed with "1800" followed by 6 digits (for local businesses); "180" or "189" followed by 7 digits usually refers to a free call to an overseas-operated calling center. The called party pays the charges for the call. As of 2012, calls from local cellular phone service providers to these prefixes are also free. Numbers prefixed with "1700" followed by 6 digits are local-rate numbers for the first 3–4 minutes, after which the charges for the remaining duration of the call are transferred to the receiving party (on a "shared cost" basis).
In Italy, toll-free numbers are dialed with the "800" or "803" prefix and are commonly referred to as numero verde (green number) or linea verde (green line). The numeri verdi used to begin with "1678" and later with "167".
In Japan, the prefixes "0120" and "0800" are officially assigned for toll-free numbers and are often referred to as or telephone numbers. These numbers are owned by NTT Communications (NTT Com). Several telephone carriers also provide toll-free services under their own company prefixes such as "0077" (these prefixes are also used for other toll services; the prefix "0570" is officially assigned for Navi Dial, a special toll service also operated by NTT Com).
In South Korea, toll-free numbers are prefixed with "080" (not to be confused with "060" or "070", which are used for pay-per-call/pay-per-minute information services or digital home phone services). Not all numbers with the "080" prefix are toll-free when called from a mobile phone.
In Latvia the prefix 8000-xx-xx is used for toll-free services. They are toll-free only when dialed from landlines, and charged the same as a land line when dialed from cell phones.
In Malaysia the prefix is 1800. Free if calling from a land-line and VoIP only. Calling from mobile phone will be considered a local call, with varying charges depending on the mobile network providers.
In Mexico the prefix is 800.
In Nepal the prefix is 1660.
In New Zealand, both "0800" or "0508" prefixes are referred to variously and interchangeably as "free phone" or "toll-free". Originally these "Oh-eight-hundred" numbers were provided by Spark New Zealand and "0508" by rival company Clear (now One New Zealand), although now both numbers can be provided by either company. Some older toll bar services designed to restrict toll calls (including long distance or calls to mobile phones) will also block calls to these free phone numbers, although this has become less common since the mid-1990s. A limited number of companies utilizing toll-free numbers will not accept calls from mobile phones. Some other free phone services exist, such as "*555" ("star five five five"), which can be dialled from cellular phones to report traffic conditions and incidents of dangerous driving.
In the Netherlands, the prefix "0800" is used for toll-free numbers. Calling 0800-numbers from fixed and mobile phones is free by law. UIFN's "00800" are generally free from fixed lines and charged for the airtime from mobile phones. UIFN access is not enforced by law, causing certain phone providers not to honor the standard.
In Norway most telephone-numbers have eight digits (with some exceptions). Toll-free numbers all begin with "800", followed by five further digits.
In Pakistan, toll-free numbers have the format "0800-xxxxx".
In Paraguay, the prefix "0800" is used for toll-free numbers, followed by 6 digits.
In the Philippines, the prefix for toll-free numbers is "1800" followed by either one, two, or four digits (examples include 8, 10, and 1888), and then by either a four- or seven-digit phone number. However, there are restrictions. Toll-free numbers are limited to the telephone network where the toll-free number is being handled. So, subscribers of a different telephone network company will not be able to call a toll-free number handled by a different telephone network. International toll-free numbers can only be accessed if the calling party is a PLDT subscriber.
In Poland, toll-free numbers have the format "800 xxx xxx". There are also split-charge numbers in the format "801 uxx xxx" (caller's cost depends on the digit u) and "universal numbers" in the format "804 uxx xxx", where the caller is automatically connected to the nearest office (these numbers are toll-free if u=3).
In Portugal, the prefix is "800" so the 9-digit number is "800 xxx xxx". It is referred as chamada gratuita (free call) or as número verde (green number).
In Qatar, toll-free numbers have the format "800' xxxx".
In Romania, toll-free numbers have the format "0800 xxx xxx". The service is referred to as număr verde.
In Russia, the prefix is "8-800", followed by 7 digits (8-800-XXX-XX-XX).
In Serbia, the prefix "0-800", followed by a 6 or 7 digit number, is used.
In Singapore, the prefix "1800" followed by a 7 digit number is used. Calling from a mobile phone network will be considered a local call and charges vary among service providers.
In Slovakia, the toll-free prefix is "0800", followed by six digits. The local rate prefix is "0850".
In Slovenia, the prefix "080" is used for toll-free numbers, followed by four more digits.
In South Africa, the prefix "080", followed by 7 digits is used. It is referred to as a "toll-free" or "080" number (Afrikaans: tol-vrye).
In Spain, the "900XXXXXX" or "800XXXXXX" numbers are always toll-free (800 numbers are not usually used), "909XXXXXX" is used for dial-up Internet service and toll-free dialup Internet service (under subscription). Also "1002", "1004", "14XX", "15XX" and "16XX" are free and are used for the telecommunication providers call centers.
In Sweden, the prefix is "020" or "0200" for toll-free numbers. (Additionally, 0800 is reserved for future use.) These numbers are unreachable from other countries.
In Switzerland, the toll-free prefix is "0800"; it used to be "155". These numbers are called grüne Nummer (German) / numéro vert (French) / numero verde (Italian), all meaning "green number".
In Taiwan, the toll-free prefix is 0800-xxx-xxx or 0809-xxx-xxx, but not all Taiwanese mobile numbers can call toll free numbers. A toll-free subscriber can decide to restrict a number due to high per-minute mobile rates. This is cumbersome for the caller, who is told to dial another landline number, usually at the highest toll rate within the country as a mobile to landline call. Some small VOIP operators also cannot call toll free numbers. For example, 0701-xxx-xxx cannot call toll free numbers directly, but can call through a live operator by dialling "123" and have them redirect the call.
In Thailand, for the Call Free, Free Call, Toll-Free, or Free Phone service, the format used is "1800-xxxxxx". Calls are free for all fixed line calls. Mobile carriers AIS and CAT (60+%o f Thailand's subscribers) offer 1-800 service for cell phones. DTAC and True mobile providers currently do not, but it is expected they will offer the 1-800 service for subscribers by late 2009.
In Turkey, the prefix for toll-free numbers is "0800".
In the United Kingdom, modern freephone numbers start with 0800 or 0808, followed by a further 7 digits. Some older 0800 numbers still in use have a shorter number length. The former 0500 freephone number range was withdrawn on 5 June 2017.
In Ukraine, toll-free numbers have the "0800" prefix, followed by 2 digits for the carrier code, then 4 digits for the client number - i.e., 0 800 YYXXXX. Before October 2009, the "8800" prefix was used.
In Vietnam, the prefix "1800" followed by a series of numbers, usually from 4 to 9 digits. All "1800" numbers are free of charge, but some of them cannot be dialled from all telephones.
In Kosovo, the toll-free prefix is "0800" followed by 5 digits.
Australia
Toll-free
Toll-free numbers in Australia are ten-digit numbers beginning with the prefix "1800".
1800 numbers can also be found in Phonewords via an online auction.
For all types, the recipient business pays for incoming toll charges, either per call or at flat rates.
In some cases, 1800 numbers can be accessed from international lines.
Callers to an 1800 number are not charged a connection fee from a domestic fixed line. Calls from a mobile phone may incur charges depending on the provider.
The original prefix was 008. Such numbers were nine digits long. For example, the Crime Stoppers toll-free hotline was 008 333 000, sometimes (misleadingly) written as (008) 33 3000. Such numbers could be dialled from outside Australia, for example +61 08 333 0000
Local Rate numbers
A system similar to 1800 numbering exists where 6 or 10 digit numbers prefixed with 13 (one-three), 1300 or 1301 (colloquially one-three-hundred) can be called at local call rates regardless of the caller's location.
Callers to a 13 number are charged a "connection fee" by their telephone provider.
13 and 1300 numbers are often "smart routed" to the local outlet of chain stores or fast food premises. They may also be used by different companies in different regions.
13 numbers, 1300 numbers and 1800 numbers are relocatable across Australia, and can be transferred between different telecommunications suppliers.
13 numbers are a premium number scheme, subject to charges from the Australian Communications & Media Authority (ACMA) of approximately $10,000 per annum collected by the supplying carrier.
Premium numbers, such as those that spell a word using keypad letters, are regularly auctioned by the ACMA.
Mobile telephones
Mobile callers are charged to phone a 1300 number or 1800 number, usually at their normal per minute rate, but sometimes at predatory rates. These expensive numbers can be decoded to ordinary landline and organisations usually offer a landline number on their websites, though it may be hard to find.
Smart routed 1800 or 13(00) numbers are sometimes not available from mobile phones as owners of the numbers may bar incoming calls from mobile devices due to higher call charges associated with such calls.
Canada
In addition to NANP toll-free numbers, carriers Bell Canada and Telus offer 310- numbers that can be accessed at local-call prices as shared-cost service (free from landlines, incurs local airtime charge from mobiles and local price from payphones). There are a few special mobile-only numbers (like *CAA to call the Canadian Automobile Association) which are free from cell phones, these are actually vertical service codes.
China
Calling an 800-number is free of charge. Calling a 400-number incurs a local access charge.
800-numbers are accessible only to land-line subscribers, while 400-numbers are accessible to all land-line and mobile users.
800-toll-free numbers
800 toll-free numbers are commonly called "800 免费电话". The official name is "被叫集中付费业务" (called party collect paid service), which means the cost of the call is borne not by the caller but by the party receiving the call.
800-toll-free numbers in China are ten-digit numbers beginning with "800". There is no prefix before "800".
800-toll-free numbers are not accessible to mobile network subscribers and some land-line subscribers. For instance China Tietong Telecom land-line users cannot access 800 numbers.
400-toll-free numbers
400-service is called "主被叫分摊付费业务" (calling party and called party split-paid service), which means the calling party pays for the local access fee and the called party pays the toll (long distance) fee.
400-toll-free numbers in China are ten-digit numbers beginning with "400".
400-toll-free numbers can be accessed by all fixed-line and mobile phones.
Callers have to bear local access charges from their service providers.
400-toll-free numbers with prefix "4001" are international toll-free numbers which can be routed to destination numbers inside or outside China. 400 toll-free numbers with prefix "4000", "4006", "4007" or "4008" are national toll-free numbers which can be routed to China destination numbers only.
Netherlands
The introduction of 0800/0900 numbers in the Netherlands in 1986 has led to significant growth of call centres and an increase in outsourcing.
Originally, free telephone numbers in the Netherlands started with either the 06-0, 06-4 or 06-3000 prefix. Most 0800-numbers cannot be called from abroad, and only few can be called from the Caribbean Netherlands (by dialing 0031800). 088-numbers are shared-cost; from landlines, the caller pays only the costs for a local call, whereas the receiver pays the rest.
United Kingdom
In the United Kingdom, toll-free telephone numbers are generally known as "freephone" numbers (British Telecom numbers use the previously trademarked term Freefone) and begin with the prefixes 0800 or 0808. The most commonly used prefix is 0800, first used in November 1985. Additionally, numbers in the range are reserved for not-for-profit helplines, through a scheme negotiated by the Helplines Partnership (now known as the Helplines Association).
Since 1 July 2015, all 0800 and 0808 numbers have been free to call from landlines and mobile phones alike. Most mobile phone operators had charged for such calls previously, with Orange being the final major network to introduce such charges during December 2005. Certain helplines, such as those in the 0808 80x xxxx series had remained free from most networks on a voluntary basis and some niche operators, such as Giffgaff always offered freephone calls at no charge.
The UK mobile operators offer an alternative product to organisations who wish to provide toll-free services - 5-digit voice short codes which are sold through mobile aggregators.
0500 numbers, introduced by Mercury Communications (later known as Cable & Wireless, now Vodafone) in 1982, were also freephone numbers (known as "FreeCall"), but were officially withdrawn by Ofcom on 3 June 2017. A three-year transition period prior to that had allowed existing subscribers to migrate to matching 080 85 numbers with the same final 6 digits as before. While the numbers had been portable, the 0500 range had been closed to new allocations since 1997/98.
0500 numbers had six more digits after the prefix. 0800 numbers can have six or seven digits after the prefix. 0808 numbers have seven digits after the prefix.
Freephone numbers in the range to are blocked out by Ofcom for use as fictitious telephone numbers.
United States
Toll-free numbers in the North American Numbering Plan (NANP) are commonly called "800-numbers" after the first area code assigned for the service. Today, several prefixes are used: 800 (since January 1, 1966), 888 (since March 1, 1996), 877 (since April 4, 1998), 866 (since July 29, 2000), 855 (since October 9, 2010), 844 (since December 7, 2013), and 833 (since June 3, 2017).
Area codes reserved for future expansion of the service include 822, 880 through 887, and 889.
The original Wide Area Telephone Service (WATS) is obsolete. North American toll-free numbers are controlled by an intelligent network database (SMS/800) in which any toll-free number may be directed to any geographic telephone number under the control of any of various RespOrgs. Direct inward dialing and toll-free number portability are supported; various providers offer gateways which receive free phone calls on PRI lines and deliver them to voice over IP or pager users.
Toll free numbers usually capture the telephone number of the caller for billing purposes through automatic number identification, which is independent of caller ID data and functions even if caller ID is blocked.
Universal International Freephone Service
Universal International Freephone Service is an international service, assigned the country code 800 by the International Telecommunication Union. The intention is that any customer in the world can dial the same number to reach a business subscribing to a number, and at no charge to the calling party. However, only a limited number of countries participate . In order to participate, countries must agree on the amount of revenue they will retain (to cover their costs of network transport) while still forwarding sufficient revenue to cover the recipient's costs of subscribing.
A Universal International Freephone Number (UIFN) is a worldwide toll-free "800 number" issued by the International Telecommunication Union. Like the 800 area code issued for the North American Numbering Plan in the United States and Canada and 0800 numbers in many other countries, the call is free for the caller while the receiver pays the charges. UIFN uses country-level calling code 800 so that no matter where the caller is, only the international access code (IAC), the UIFN country code (800) and the 8-digit UIFN need to be dialed. As of March 2020, 144 carriers in 67 countries participate in the UIFN program; free access to the numbers (as international calls) from mobile and coin telephones is not universal. Registration of a +800 number incurs a 300 Swiss franc ITU fee (as of 2018) in addition to any charges levied by the individual carrier. The number must be activated for inbound calls from at least two telephone country codes within 180 days.
The +800 UIFN service is one of three ITU-administered non-geographic codes with a similar numbering scheme. The +808 Universal International Shared Cost Number (UISCN), billed at the price of a domestic call, shares the same eight-digit format; the +979 Universal International Premium Rate Number (UIPRN), billed at a high premium cost, carries one extra digit to indicate price range.
See also
SMS/800 and RespOrg
900 number
Collect call
Freepost
Mobile dial code
Wide Area Telephone Service
Zenith number
References
Telephone numbers | Toll-free telephone number | Mathematics | 7,447 |
32,517,295 | https://en.wikipedia.org/wiki/Terumo%20Penpol | Terumo Penpol Private Limited is a subsidiary of Terumo Corporation, and is India's largest blood bag manufacturer. It is also the largest producers of blood bags in Asia, outside Japan.
History
Peninsula Polymers Limited (Penpol Ltd.) - was incorporated in 1983 by C. Balagopal, a former IAS (1977 Batch) officer from the Manipur Cadre. It was established as a joint venture with Sree Chitra Thirunal Institute of Medical Sciences and Technology (know fhen as the Chitra Medical Centre) and soon became the first company in India to produce blood bags using indigenous technology. In 1989, Penpol started exporting and followed it up by setting up an R&D centre.
In 1999, Tokyo-based Terumo Corporation signed a contract to acquire a 74% share of Peninsula Polymers Limited, and the new joint venture was renamed as Terumo Penpol Limited (TPL). The stake of financial institutions and other investors were bought over by Terumo, leaving only the promoters and itself as shareholders.
Operations
Terumo Penpol has its headquarters in Thiruvananthapuram, Kerala and employs 1200 people. Terumo Penpol Blood Bags are sold in over 64 countries across the world and its medical equipment division has commissioned more than 25000 installations. TPL has entered its 25-year of operations in 2010, with an enhanced production capacity of 22 million blood bags per annum.
TPL has been winning the top exporter award or the second best exporter award for medical disposables every year from 1994 onwards.
References
External links
Terumo Penpol Ltd.
Terumo Corporation Japan
https://cb.hbsp.harvard.edu/cbmp/product/NA0294-PDF-ENG Harvard case study on PENPOL
Companies established in 1987
Biomedical engineering | Terumo Penpol | Engineering,Biology | 382 |
74,911,177 | https://en.wikipedia.org/wiki/Conocybe%20macrospora | Conocybe macrospora is a species of mushroom-producing fungus in the family Bolbitiaceae.
Taxonomy
It was described in 1918 by the American mycologist George Francis Atkinson who classified it as Galerula macrospora.
In 1929 John Eugene Sass described Galera tenera f. bispora as a form variant of Galera tenera (now known as Conocybe tenera) which differed from this species by virtue of having two spored basidia with examination of the basidia being the only means noted of distinguishing them. This form is listed as a synonym of Conocybe macrospora by species fungorum.
In 1971 Conocybe ochracea f. macrospora was described by Robert Kühner and Roy Watling and Conocybe rubiginosa as described by Watling is now also considered a synonym.
In 2003 the species was reclassified as Conocybe macrospora by Anton Hausknecht and in Conocybe pubescens var. macrospora as described in 2007 by Erhard Ludwig is now also considered a synonym.
Description
Cap: 0.6–2.5 cm wide and 0.5–2.2 cm tall or up to 4 cm wide and 3 cm tall in the largest specimens, campanulate to convex and often as high as it is wide. The surface is pale orange to brown, hygrophanous and moist with striations running almost to the centre. It is smooth but when viewed under a magnifying glass has fine hairs. Gills: Adnexed, crowded and light yellow brown to light rusty brown with a slight ventricose bulge and lighter edge. Stem: 3.1–10 cm long and 1-3mm thick or up to 15 cm long and 4mm thick in the largest specimens. It is cylindrical with a slightly bulbous base that is 2-6mm thick. The surface is orange yellow with a yellow tip when immature and uniformly brassy yellow to orangy yellow when mature often with a slightly darker orange brown base when old. Longitudinal striations run up the length of the stem and the surface has some hairs. Flesh: Whitish to light yellow in the cap and orangish yellow in the stem. Smell: Odourless or slightly radish like when crushed. Taste: Indistinct.
Microscopic details
Spores: (11.5) 13.5–21 (23.5) x 7.5–11 (12.5) μm or (15.1) 15.6–19 x 7.8–10.6 μm on average. Ellipsoidal or rarely slightly limoniform (lemon shaped) with a thick wall and large 2–4 μm wide germ pore. Orange-brown to reddish-brown in KOH. Basidia: 18–30 x 9–13.5 μm. 2 spored. Round-petiolate to barrel shaped. Cheilocystidia: 15–22.5 x 6–11 μm. Lecythiform (skittle shaped) with a large 3–4 (5) μm head and thick short neck. Caulocystidia: Mix of lecythiform similar to cheilocystidia but larger and non-lecythiform hairs almost evenly distributed over the length of the stem.
Habitat and distribution
The specimens studied by Atkinson were found growing on the ground amongst mixed grassed and moss on the edge of a coniferous wood near Stockholm, Sweden. Hausknecht described them as growing in grassy, nitrate-rich meadows or in dung, disturbed ground, compost and rarely in leaf litter or on the edge of burnt areas. It is common in Europe and Hausknecht's description was based on collection in Austria in Italy.
References
Bolbitiaceae
Fungi described in 1918
Fungi of Europe
Fungus species | Conocybe macrospora | Biology | 808 |
16,543,596 | https://en.wikipedia.org/wiki/Orion%20correlation%20theory | The Orion correlation theory is a fringe theory in Egyptology attempting to explain the arrangement of the Giza pyramid complex.
It posits that there is a correlation between the location of the three largest pyramids of the Giza pyramid complex and Orion's Belt of the constellation Orion, and that this correlation was intended as such by the original builders of the Giza pyramid complex. The stars of Orion were associated with Osiris, the god of rebirth and afterlife by the ancient Egyptians. Depending on the version of the idea, additional pyramids can be included to complete the picture of the Orion constellation, and the Nile river can be included to match with the Milky Way.
The idea was first published in 1989 in Discussions in Egyptology, volume 13. It was the subject of the book The Orion Mystery, in 1994, as well as a BBC documentary, The Great Pyramid: Gateway to the Stars (February 1994), and appears in some New Age books.
History
The Orion correlation theory was put forward by Robert Bauval, and mentioned that Mintaka, the dimmest and most westerly of the stars making up Orion's belt, was offset slightly from the others. Bauval then made a connection between the layout of the three main stars in Orion's belt and the layout of the three main pyramids in the Giza pyramid complex. He published this idea in 1989 in the journal Discussions in Egyptology, volume 13. The idea has been further expounded by Bauval in collaboration with pseudoscientific authors Adrian Gilbert (The Orion Mystery, 1994) and Graham Hancock (Keeper of Genesis, 1996), as well as in their separate publications. The basis of this idea concerns the proposition that the relative positions of three main Ancient Egyptian pyramids on the Giza plateau was by design correlated with the relative positions of the three stars in the constellation of Orion which make up Orion's Belt, as these stars appeared in 10,000 BC.
Their initial ideas regarding the alignment of the Giza pyramids with Orion: "...the three pyramids were a terrestrial map of the three stars of Orion's belt" are later joined with speculation about the age of the Great Sphinx. According to these works, the Great Sphinx was constructed c. 10,500 BC (Upper Paleolithic), and its lion-shape is maintained to be a definitive reference to the constellation of Leo. Furthermore, the orientation and dispositions of the Sphinx, the Giza pyramids and the Nile River relative to one another on the ground is put forward as an accurate reflection or "map" of the constellations of Leo, Orion (specifically, Orion's Belt) and the Milky Way respectively. As Hancock puts it in 1998's The Mars Mystery (co-authored with Bauval):
The allusions to dates circa 12,500 years ago are significant to Hancock since this is the era he seeks to assign to the advanced progenitor civilization, now vanished, but which he contends through most of his works had existed and whose advanced technology influenced and shaped the development of the world's known civilizations of antiquity. Egyptology and archaeological science maintain that available evidence indicates that the Giza pyramids were constructed during the Fourth dynasty period (3rd millennium BC), while the exact date of the Great Sphinx is still unclear.
Critique
Arguments made by Hancock, Bauval, Anthony West and others concerning the significance of the proposed correlations have been described as a form of pseudoarchaeology.
Among these are critiques from two astronomers, Ed Krupp of Griffith Observatory in Los Angeles and Tony Fairall of the University of Cape Town, South Africa. Using planetarium equipment, Krupp and Fairall independently investigated the angle between the alignment of Orion's Belt and north during the era cited by Hancock, Bauval, et al. (which differs from the angle seen today or in the third millennium BC, because of the precession of the equinoxes). They found that the angle was somewhat different from the "perfect match" thought to exist by Bauval and Hancock in the Orion correlation theory. They estimate 47–50 degrees per the planetarium measurements, compared to the 38-degree angle formed by the pyramids.
Krupp pointed out that the slightly bent line formed by the three pyramids was deviated towards the north, whereas the slight "kink" in the line of Orion's Belt was deformed to the south, and to match them up one or the other of them had to be turned upside-down. Indeed, this is what was done in the original book by Bauval and Gilbert (The Orion Mystery), which compares images of the pyramids and Orion without revealing that the pyramids' map had been inverted. Krupp and Fairall found other problems with their arguments, including noting that if the Sphinx is meant to represent the constellation of Leo, then it should be on the opposite side of the Nile (the "Milky Way") from the pyramids ("Orion"), that the vernal equinox c. 10,500 BC was in Virgo and not Leo, and that in any case the constellations of the Zodiac originate from Mesopotamia and were completely unknown in Egypt until the much later Graeco-Roman era. Ed Krupp repeated this "upside down" statement in the BBC documentary Atlantis Reborn (1999).
BBC documentary
On 4 November 1999, the BBC broadcast a documentary entitled Atlantis Reborn which tested the ideas of Robert Bauval and his colleague, Graham Hancock. Bauval and Hancock afterwards complained to the Broadcasting Standards Commission (BSC) that they had been treated unfairly.
A hearing followed and in November 2000 the BSC ruled in favour of the documentary makers on all but one of the ten principal complaints brought by Hancock and Bauval. The one complaint upheld regarded the omission of their rebuttal of a specific argument against the Orion Correlation Theory. In regard of the nine remaining principal complaints, the BSC ruled against Hancock and Bauval, concluding that they had not been treated unfairly in the criticism of their theories concerning carbon-dating, the Great Sphinx of Egypt, Cambodia's Angkor temples, Japan's Yonaguni formation and the mythical land of Atlantis.
The BBC offered to broadcast a revised version of the documentary, which was welcomed by Hancock and Bauval. It was broadcast as Atlantis Reborn Again on 14 December 2000. The revised documentary continued to present serious doubts about Bauval and Hancock's ideas, as held by astronomer Anthony Fairall, Ed Krupp of the Griffith Observatory, Egyptologist Kate Spence of Cambridge University and Eleanor Mannikka of the University of Michigan.
Leo and the Sphinx
The Great Sphinx of Giza is commonly accepted by Egyptologists to represent the likeness of King Khafre who is often credited as the builder as well. This would place the time of construction somewhere between 2520 BC and 2494 BC. Because the limited evidence giving provenance to Khafre is ambiguous, the idea of who built the Sphinx, and when, continues to be the subject of debate.
An argument put forward by Bauval and Hancock to support the Orion Correlation Theory is that the construction of the Great Sphinx was begun in 10,500 BC; that the Sphinx's lion-shape is a definitive reference to the constellation of Leo; and that the layout and orientation of the Sphinx, the Giza pyramid complex and the Nile River are an accurate reflection or "map" of the constellations of Leo, Orion (specifically, Orion's Belt) and the Milky Way, respectively.
A date of 10,500 BC is chosen because they maintain this is the only time in the precession of the equinoxes when the astrological age was Leo and when that constellation rose directly east of the Sphinx at the vernal equinox. They also suggest that in this epoch the angles between the three stars of Orion's Belt and the horizon were an "exact match" to the angles between the three main Giza pyramids. These propositions and other theories are used to support the overall belief in an advanced and ancient, but now vanished, global progenitor civilization.
The supposition that the Sphinx is far older has received very limited support from geologists. Robert M. Schoch has argued that the effects of water erosion on the Sphinx and its surrounding enclosure mean that parts of the monument must originally have been carved at the latest between 7000–5000 BC. Colin Reader has suggested a date only several hundred years prior to the commonly accepted date for construction. These views have been almost universally rejected by mainstream Egyptologists who, together with a number of geologists including James Harrell, Lal Gauri, John J. Sinai, and Jayanta K. Bandyopadhyay, stand by the conventional dating for the monument. Their analyses attribute the apparently accelerated wear on the Sphinx variously to modern industrial pollution, qualitative differences between the layers of limestone in the monument itself, scouring by wind-borne sand, or temperature changes causing the stone to crack.
References
External links
"The Giza Pyramids as a Stellar Representation of Orion's Belt" by Robert Bauval
"The Orion Correlation and Air-Shaft Theories" by John A.R. Legon
"Pyramid Marketing Schemes" by E. C. Krupp
"The Fundamental Flaws in the Orion-Giza Correlation Theory" by Ian Lawton
1989 introductions
Orion (constellation)
Archaeological controversies
Pseudoscience
Pyramidology
Giza pyramid complex
Fringe theories | Orion correlation theory | Astronomy | 1,954 |
3,291,096 | https://en.wikipedia.org/wiki/Combined%20gas%20or%20gas | Combined gas or gas (COGOG) is a propulsion system for ships using gas turbine engines.
System
A high efficiency, low output turbine is used for cruising speeds with a high output turbine being used for high-speed operations. A clutch allows either turbine to be selected, but there is no gearbox to allow operation of both turbines at once. This has the advantage of not requiring heavy, expensive and potentially unreliable gearboxes. The reason that a smaller turbine is used for cruising is that a small turbine running at 100% power is more fuel efficient than a bigger turbine running at 50% power.
The system is currently used in the 2 ships of the Russian Navy's s, the Japanese Maritime Self-Defense Force's Hatsuyuki-class destroyers, and the Royal Netherlands Navy s (on which the Greek Navy s are based). It was formerly used in the Royal Navy's Type 42 destroyer and Type 22 frigate, as well as the Royal Canadian Navy's Iroquois-class destroyer.
Development
Having previously pioneered the combined diesel or gas (CODOG) system, in 1968 the Royal Navy converted an old frigate, , to COGOG propulsion as a test bed for use in later ships. Because developing a new gas turbine purely for marine use would be very expensive, it was decided to adapt a Rolls-Royce Olympus engine, which had been originally designed for the Avro Vulcan bomber and further developed for the Concorde supersonic airliner. Cruising power was provided by two Rolls-Royce Proteus gas turbines, originally designed for turboprop airliners, each rated at . The Olympus had to be down-rated to to keep within the limits of the Exmouth's hull structure.
Even before the Exmouth trials had started, the Royal Navy had already ordered the first class of vessels to be designed from the start for COGOG propulsion, the Type 21 frigates, in which the Proteus turbines were replaced by a pair of Rolls-Royce Tyne engines. The Tynes were rated at each, giving a cruising speed , while an Olympus rated at 25,000 shp gave a maximum speed of . However, they were beaten into service by the Canadian s, which were powered by two Pratt & Whitney FT4A2 gas turbines creating and two Pratt & Whitney FT12AH3 cruising gas turbines creating , giving a maximum speed of .
Disadvantages
The operation of large gas turbines on ships produces a high volume of very hot exhaust gasses, which can hinder onboard helicopter operations, and also greatly increases a ship's infrared signature making it more conspicuous to enemy sensors and guided weapons. The ducting and filters required take up a considerable amount of space in a ship, and the volume of air being drawn in can exacerbate an internal fire. This was found to be a factor in the loss of during the 1982 Falklands War. Many navies have now abandoned pure gas turbine propulsion in favour of combined diesel-electric and gas (CODLAG) systems.
References
Marine propulsion | Combined gas or gas | Engineering | 607 |
31,979,720 | https://en.wikipedia.org/wiki/Silvicide |
As herbicides are pesticides used to kill unwanted plants, silvicides are special pesticides (cacodylic acid or MSMA, for instance) used to kill brush and trees. They can wipe out entire forests or specific, unwanted forest species.
See also
Bioherbicide
Deforestation
List of environmental health hazards
Soil contamination
Surface runoff
References
Further reading
Allard, J. (1974) Arsenical silvicide effects on human health. See Norris, L.A. (1974a). p 4.
Tarrant, R.F. and Allard, J. (1972) Arsenic levels in urine of forest workers applying silvicides. Arch. Envir. Health 24:277-280.
External links
General Information
National Pesticide Information Center, Information about pesticide-related topics
National Agricultural Statistics Service
Regulatory policy
US EPA
UK Pesticides Safety Directorate
European Commission pesticide information
pmra Pest Management Regulatory Agency of Canada
Herbicides | Silvicide | Biology | 195 |
69,191,109 | https://en.wikipedia.org/wiki/Interning%20%28computer%20science%29 | In computer science, interning is re-using objects of equal value on-demand instead of creating new objects. This creational pattern is frequently used for numbers and strings in different programming languages. In many object-oriented languages such as Python, even primitive types such as integer numbers are objects. To avoid the overhead of constructing a large number of integer objects, these objects get reused through interning.
For interning to work the interned objects must be immutable, since state is shared between multiple variables. String interning is a common application of interning, where many strings with identical values are needed in the same program.
History
Lisp introduced the notion of interned strings for its symbols. The LISP 1.5 Programmers Manual describes a function called intern which either evaluates to an existing symbol of the supplied name, or if none exists, creates a new symbol of that name. This idea of interned symbols persists in more recent dialects of Lisp, such as Clojure in special forms such a (def symbol) which perform symbol creation and interning.
In the object-oriented programming paradigm interning is an important mechanism in the flyweight pattern, where an interning method is called to store the intrinsic state of an object such that this can be shared among different objects which share different extrinsic state, avoiding needless duplication.
Interning continues to be an important technique for managing memory use in programming language implementations; for example, the Java Language Specification requires that identical string literals (that is, literals that contain the same sequence of code points) must refer to the same instance of class String, because string literals are "interned" so as to share unique instances. In the Python programming language small integers are interned, though the details of exactly which are dependent on language version.
Motivation
Interning saves memory and can thus improve performance and memory footprint of a program. The downside is time required to search for existing values of objects which are to be interned.
See also
Flyweight pattern
Hash consing
References
External links
Design Patterns - University of Washington
String interning in Python
A standard library package for interning in Go - The Go Blog
Software optimization
String (computer science) | Interning (computer science) | Mathematics,Technology | 445 |
4,707,640 | https://en.wikipedia.org/wiki/Galeb%20%28computer%29 | Galeb () was an 8-bit computer developed by the PEL Varaždin company in Yugoslavia in the early 1980s. A grand total of 250 were produced by the end of the summer of 1984, before being replaced with the Orao.
Galeb was designed by Miroslav Kocjan and inspired by Compukit UK101, Ohio Scientific Superboard and Superboard II computers. These machines appeared in the UK and USA in 1979 and were less expensive than Apple II, Commodore PET and/or TRS-80 computers. Galeb's codename YU 101 was chosen to resemble Compukit's UK101.
Galeb was very similar to computers that inspired it:
Specifications:
CPU: MOS Technology 6502
ROM: 16 KB (with modified Microsoft BASIC interpreter and Machine code monitor)
RAM: 9 KB (expandable to 64 KB)
Keyboard: 59-key QWERTZ
I/O ports: composite video and RF TV out, cassette tape interface (DIN-5), RS-232 (D-25), edge expansion connector
Sound: Internal speaker; single-channel, 5 octaves
Graphics: monochrome, 96×48 pixels
Text mode: 48x16 characters
Price: 90,000 dinars (in 1984)
Emulation of this machine is supported by MESS since 2008 (version 0.124), along with dedicated emulators.
References
Computer-related introductions in 1981
Personal computers | Galeb (computer) | Technology | 294 |
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