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54,442,182 | https://en.wikipedia.org/wiki/Flupamesone | Flupamesone (brand name Flutenal), also known as triamcinolone acetonide metembonate, is a synthetic glucocorticoid corticosteroid which is marketed in Spain. It is a dimer of a C21 ester of triamcinolone acetonide.
References
Acetonides
Corticosteroid cyclic ketals
Corticosteroid esters
Dimers (chemistry)
Diols
Organofluorides
Glucocorticoids
Naphthalenes
Polyketones
Pregnanes | Flupamesone | [
"Chemistry",
"Materials_science"
] | 116 | [
"Dimers (chemistry)",
"Polymer chemistry"
] |
54,442,183 | https://en.wikipedia.org/wiki/Itrocinonide | Itrocinonide (developmental code name D5159) is a synthetic glucocorticoid corticosteroid which was never marketed.
References
Secondary alcohols
Corticosteroid cyclic ketals
Cyclic acetals with aldehydes
Organofluorides
Glucocorticoids
Pregnanes
Abandoned drugs | Itrocinonide | [
"Chemistry"
] | 72 | [
"Drug safety",
"Abandoned drugs"
] |
54,442,184 | https://en.wikipedia.org/wiki/Rofleponide | Rofleponide is a synthetic glucocorticoid corticosteroid which was never marketed.
References
Corticosteroid cyclic ketals
Cyclic acetals with aldehydes
Diketones
Diols
Organofluorides
Glucocorticoids
Pregnanes
Abandoned drugs | Rofleponide | [
"Chemistry"
] | 65 | [
"Drug safety",
"Abandoned drugs"
] |
54,442,186 | https://en.wikipedia.org/wiki/Triclonide | Triclonide (developmental code name RS-4464) is a synthetic glucocorticoid corticosteroid which was never marketed.
References
Acetonides
Organochlorides
Corticosteroid cyclic ketals
Diketones
Organofluorides
Glucocorticoids
Pregnanes
Abandoned drugs | Triclonide | [
"Chemistry"
] | 70 | [
"Drug safety",
"Abandoned drugs"
] |
54,442,348 | https://en.wikipedia.org/wiki/Cortisuzol | {{Drugbox
| Verifiedfields =
| Watchedfields =
| verifiedrevid =
| IUPAC_name = 4-({2-[(1R,2R,3aS,3bS,10aR,10bS,11S,12aS)-1,11-Dihydroxy-2,5,10a,12a-tetramethyl-7-phenyl-1,2,3,3a,3b,7,10,10a,10b,11,12,12a-dodecahydrocyclopenta[5,6]naphtho[1,2-f]indazol-1-yl]-2-oxoethoxy}carbonyl)benzenesulfonic acid
| image = Cortisuzol.svg
| width =
| tradename = Solu-Altim
| pregnancy_AU =
| pregnancy_US =
| pregnancy_category =
| legal_AU =
| legal_CA =
| legal_UK =
| legal_US =
| legal_status =
| routes_of_administration =
| bioavailability =
| protein_bound =
| metabolism =
| elimination_half-life =
| excretion =
| CAS_number_Ref =
| CAS_number = 50801-44-0
| CAS_supplemental =
| class = Corticosteroid; Glucocorticoid
| ATC_prefix =
| ATC_suffix =
| ATC_supplemental =
| PubChem = 3037936
| IUPHAR_ligand =
| DrugBank_Ref =
| DrugBank =
| ChemSpiderID_Ref =
| ChemSpiderID = 16736901
| UNII = 1PA76KJ99Y
| KEGG =
| ChEBI =
| ChEMBL = 2106054
| C=37 | H=40 | N=2 | O=8 | S=1
| SMILES = C[C@@H]1C[C@H]2[C@@H]3C=C(C4=CC5=C(C[C@@]4([C@H]3[C@H](C[C@@]2([C@]1(C(=O)COC(=O)C6=CC(=CC=C6)S(=O)(=O)O)O)C)O)C)C=NN5C7=CC=CC=C7)C
| StdInChI_Ref =
| StdInChI = 1S/C37H40N2O8S/c1-21-13-27-29-14-22(2)37(43,32(41)20-47-34(42)23-9-8-12-26(15-23)48(44,45)46)36(29,4)18-31(40)33(27)35(3)17-24-19-38-39(30(24)16-28(21)35)25-10-6-5-7-11-25/h5-13,15-16,19,22,27,29,31,33,40,43H,14,17-18,20H2,1-4H3,(H,44,45,46)/t22-,27+,29+,31+,33-,35+,36+,37+/m1/s1
| StdInChIKey_Ref =
| StdInChIKey = ZKIDWWQMNXGYHV-BYJSBFAFSA-N
| synonyms = RU-16999; 11β,17α,21-Trihydroxy-6,16α-dimethyl-2'-phenyl-2H-pregna-2,4,6-trieno[3,2-c]pyrazol-20-one 21-(m''-sulfobenzoate)
}}Cortisuzol (brand name Solu-Altim; developmental code name RU-16999''') is a synthetic glucocorticoid corticosteroid.
References
Benzoate esters
Ketones
Glucocorticoids
Sulfonic acids
Phenyl compounds
Pregnanes
Pyrazoles | Cortisuzol | [
"Chemistry"
] | 942 | [
"Ketones",
"Functional groups",
"Sulfonic acids"
] |
54,442,350 | https://en.wikipedia.org/wiki/Naflocort | Naflocort (developmental code name SQ-26490) is a synthetic glucocorticoid corticosteroid which was never marketed.
References
Diketones
Diols
Organofluorides
Glucocorticoids
Tetralins
Pregnanes
Abandoned drugs | Naflocort | [
"Chemistry"
] | 59 | [
"Drug safety",
"Abandoned drugs"
] |
54,442,351 | https://en.wikipedia.org/wiki/Nicocortonide | Nicocortonide is a synthetic glucocorticoid corticosteroid which was never marketed.
See also
Proligestone
References
Secondary alcohols
Corticosteroid cyclic ketals
Corticosteroid esters
Corticosteroids
Cyclic acetals with aldehydes
Glucocorticoids
Nicotinate esters
Pregnanes
Abandoned drugs | Nicocortonide | [
"Chemistry"
] | 81 | [
"Drug safety",
"Abandoned drugs"
] |
54,442,353 | https://en.wikipedia.org/wiki/Oxisopred | Oxisopred is a synthetic glucocorticoid corticosteroid which was never marketed.
References
Glucocorticoids
Triketones
Triols
Abandoned drugs | Oxisopred | [
"Chemistry"
] | 39 | [
"Drug safety",
"Abandoned drugs"
] |
54,442,938 | https://en.wikipedia.org/wiki/Colestolone | Colestolone (, ), also known as 5α-cholest-8(14)-en-3β-ol-15-one, is a potent inhibitor of sterol biosynthesis which is described as a hypocholesterolemic (lipid-lowering) agent. It was first reported in 1977 and was studied until at least 1988, but was never introduced for medical use.
Colestolone has been found to significantly reduce serum levels of cholesterol both in animals and in humans. It inhibits multiple relatively early-stage steps in cholesterol biosynthesis such as HMG-CoA reductase and does not appear to affect any late-stage steps (after squalene, specifically). Unlike late-stage cholesterol biosynthesis inhibitors like triparanol and azacosterol, no accumulation of sterols has been observed in animals treated with colestolone, suggesting that it does not share the toxicity of late-stage cholesterol biosynthesis inhibitors.
In addition to its potent inhibition of cholesterol biosynthesis, it is notable that colestolone also happens to serve as a precursor of cholesterol, and is efficiently converted into it in rat liver homogenates and upon oral administration to rats.
References
Abandoned drugs
Secondary alcohols
Hypolipidemic agents
Hydroxyketones
Statins
Steroidogenesis inhibitors
Sterols | Colestolone | [
"Chemistry"
] | 296 | [
"Drug safety",
"Abandoned drugs"
] |
54,443,743 | https://en.wikipedia.org/wiki/Active%20power%20filter | Active power filters (APF) are filters, which can perform the job of harmonic elimination. Active power filters can be used to filter out harmonics in the power system which are significantly below the switching frequency of the filter. The active power filters are used to filter out both higher and lower order harmonics in the power system.
The main difference between active power filters and passive power filters is that APFs mitigate harmonics by injecting active power with the same frequency but with reverse phase to cancel that harmonic, where passive power filters use combinations of resistors (R), inductors (L) and capacitors (C) and does not require an external power source or active components such as transistors. This difference, make it possible for APFs to mitigate a wide range of harmonics.
See also
Static synchronous series compensator
Power conditioner
Active filter
Line filter
References
Filters
Power engineering | Active power filter | [
"Chemistry",
"Engineering"
] | 191 | [
"Chemical equipment",
"Filters",
"Energy engineering",
"Filtration",
"Power engineering",
"Electrical engineering"
] |
54,443,915 | https://en.wikipedia.org/wiki/Building%20Regulations%20Advisory%20Committee | The Building Regulations Advisory Committee (BRAC) was an advisory non-departmental public body of the government of the United Kingdom.
The Building Regulations Advisory Committee was a statutory advisory body that the Secretary of State consulted on proposals to make or change building regulations. In addition the Committee provided expert advice to the Secretary of State on building regulations or related matters. This includes for example the health and safety, welfare and convenience of people in and around buildings; energy conservation and the sustainability of buildings.
It was officially replaced by the Building Advisory Committee (BAC) and the new Industry Competence Committee (ICC) and both help the Building Safety Regulator to meet its duty to keep the safety and standards of all buildings.
Composition
BRAC membership consisted of independent volunteers appointed due to their experience and expertise across the construction sector. Members were appointed for a 3-year term and can serve for a maximum of 3 terms.
Sub-committees
The Building Control Performance Standards Advisory Group (BCPSAG) advised BRAC for England and BRAC for Wales on the performance of building control bodies.
The Competent Person Forum advised BRAC for England and BRAC for Wales on matters of interest for Competent Person Schemes who undertake self-certified building work in England and Wales.
Abolition
BRAC was abolished by the Building Safety Act 2022, which created the Building Safety Regulator to advise the government on the safety and standard of all buildings.
References
External links
This article contains quotations from this source, which is available under the Open Government Licence v3.0. © Crown copyright.
Construction trade groups based in the United Kingdom
Housing in the United Kingdom
Defunct non-departmental public bodies of the United Kingdom government | Building Regulations Advisory Committee | [
"Engineering"
] | 332 | [
"Architecture stubs",
"Architecture"
] |
54,445,465 | https://en.wikipedia.org/wiki/Neutrophil%20swarming | Neutrophil swarming is a type of coordinated neutrophil movement that acts in response to acute tissue inflammation or infection. The term comes from the swarming characteristics of insects that are similar to the behavior of neutrophils in response to an infection. These processes have mostly been studied in tissues of mice and studies of mouse ear tissue has proved to be very effective at observing neutrophil movement. Neutrophil swarming typically aggregates at surface layers of tissue so the thin nature of the mouse ear tissue makes for a good model to study this process. Additionally, zebrafish larvae have been used for the study of neutrophil movement mainly because of their translucence during the first few days of their development. With transgenic lines that fluorescently label zebrafish neutrophils, the cells can be tracked by epifluorescence or confocal microscopy during the course of an inflammatory response. Through this method, specific subpopulations of neutrophils can be tracked and their origin and fate during the induction and resolution of inflammation is observed. Another advantage for using zebrafish to study neutrophil swarming is that adaptive immunity for this organism does not develop until around 4 weeks of age. This allows for the study of neutrophil movement and other host immune responses independent of adaptive immune responses.
History
Originally, neutrophils were once seen as a solely homogenous (of the same type) populations but as of late, there had been discoveries that show that this is not the case. Instead, they are a mixture (heterogeneity) of mature neutrophils as they have been divided based on their production of cytokine expression of TLR (toll-like receptors), activation of macrophages in immunological responses, and host resistance, and lastly, in vitro angiogenesis and tumorigenesis.
Communication
Neutrophils have two different forms of communication: homotypic and heterotypic. Homotypic communication, which is between a neutrophil and another neutrophil, is involved in the signaling when their bodies are fighting infections and inflammation. In order to carry out this type of communication, the neutrophils must cross the vascular endothelium and the basal membrane to pass into the interstitial space (IF). These are assisted by chemoattractant gradients as well as signal relays that interact between the neutrophils to carry out this signaling. In addition with communication with each other, the neutrophils must also communicate with the leukocytes (white blood cells) that are directly involved with immunological functions in the bodies of the neutrophils. This would be considered the heterotypic form of communication (neutrophil to leukocyte). Some of the functions of heterotypic communication include regulating when effector molecules are distributed, conducting immune responses, and also leaving lasting effects on cells even once they have been removed. This type of communication can also be referred to as cross-talk.
Variations
A study of the lymph nodes of mice that were infected by injection of parasites into their earflaps revealed two types of neutrophil swarming: transient and persistent swarms. Transient swarms are characterized by groups of 10-150 neutrophils forming multiple small cell clusters within 10–40 minutes that quickly dispersed. Once the neutrophils moved dispersed, they join other close swarm centers and this oftentimes leads to competition as the neutrophil groups fight for recruiting neutrophils. Persistent swarms showed clusters of more than 300 neutrophils and recruitment lasted for more than 40 minutes. These persistent swarms are also characterized by having constant neutrophil recruitment with large-cell clustering, stable and longer term than transient (a few hours). For both the transient and persistent swarms, the formed neutrophil clusters appeared to be competing with each other with the larger clusters attracting neutrophils from the smaller clusters. The study also revealed two distinct phases in swarm formation. The first phase occurs when a small number of “pioneer” neutrophils respond to an initial signal and form small clusters and this is followed by the second phase where there are a large scale migration of neutrophils leading to the growth of multiple cell clusters. In terms of migration, neutrophils will do something called chemotactic migration in which they go into and out of a swarm center by accumulation (moving towards) or moving out. Another movement is with just individual neutrophils that go will go from one swarm to another when they are in competition. One interesting fact about these two swarm types is that they can work together in the same disrupted tissue in order to restore an inflamed tissue to its original composition.
The exact size or duration of swarms depends on the specific inflammatory conditions as well as the tissue type of the infection location. Several factors that influence the swarm phenotype are: the size of the initial tissue damage, the presence of pathogens, the induction of secondary cell death, and the number of recruited neutrophils. A study that compared large scale tissue damage of sterile mouse tissue by a needle prick with small injuries by a laser beam showed that the needle prick provoked a larger and longer swarm response. After the needle injury, hundreds to thousands of neutrophils were recruited that formed stable cell clusters that sometimes were prolonged for days. In comparison, the neutrophil swarms resulting from the laser induced injury only recruited around 50-330 neutrophils which persisted for a few hours. The presence of pathogens can also increase the size of neutrophil swarms, not necessarily because of their presence as a foreign body, but because of the additional cell death that they can cause in infection sites. When cells are lysed in an infection site, they release an assortment of signaling factors that augment the recruitment of neutrophils to the site. Additionally, neutrophil death during a swarm releases more signaling factors to recruit more neutrophils so the initial amount of neutrophils recruited plays a role in how large the propagation effect is during swarming.
Stages
Stages 1-3
The neutrophil swarming process is categorized into 5 phases: swarm initiation, swarm amplification, additional swarm amplification through intercellular signaling, swarm aggregation and tissue remodeling, and recruitment of myeloid cells and swarm resolution. The first stage of neutrophil swarming details the “pioneer” neutrophils responding to an infection or inflammation site. The neutrophils close to the injury will switch from random motility to chemotactic movement within a period of 5–15 minutes and swarm towards the infection site. In the second stage, the pioneer neutrophils attract a second wave of neutrophils that come from more distant regions of the tissue. The methods of movement to the region of injury depends on the tissue environment the neutrophils are moving towards. Neutrophil swarming in extravascular spaces such as the connective tissue in the skin involves movement without the assistance of integrin proteins and neutrophil attraction by a gradient of chemoattractants. Neutrophils will be guided by the forces generated by the actomyosin cytoskeleton through the path of least resistance to the site of infection. However, for intravascular tissue environments, neutrophil movement is dependent on integrins and chemoattractant signals on the luminal surface of endothelial cells. In this process, distant neutrophils will be recruited by an inflammatory signal and perform integrin-mediated crawling along the vascular walls to reach the neutrophil swarming sites.
In the third stage, swarming neutrophils can amplify their recruitment in a feed forward manner through intercellular communication by leukotriene B4 (LTB4). The propagation of neutrophil recruitment leads to multiple, dense neutrophil cell clusters at the site of inflammation. A 2013 study showed that neutrophils lacking the high affinity receptor for LTB4 (LTB4R1) decreased the recruitment of neutrophils at later stages of swarming. In addition, proximal cells to the inflammation site showed chemotaxis similar to the control cells while distant cells were poorly attracted. This finding suggests that the proximal neutrophils that are recruited early on are not affected by the lack of LTB4R1, but distant neutrophils that are required for the propagation of neutrophil swarming are not able to be recruited to the swarming site. These results present LTB4 as a key signaling molecule for a prolonged neutrophil swarm response and recruitment of neutrophils from distant areas of the tissue.
Stages 4-5
After stages 1–3, neutrophils slow down in the cell clusters and begin to form aggregates. In this fourth stage, the neutrophil aggregates will aid in rearranging the surrounding extracellular tissue area and create a collagen-free zone at the inflammation center eventually resulting in a wound seal which isolates the site from the rest of the tissue. The exact mechanisms of this are unknown but it is believed that neutrophil proteases from the cell clusters play a role in clearing out the surrounding tissue environment. These neutrophil aggregates become stable as opposed to the constant movement in stages 1–3 by development of high chemoattractant concentrations within the clusters that promote local neutrophil interactions within the cluster. Additionally, neutrophils are switched to an adhesive mode of migration within clusters which further stabilize the aggregates and can prevent neutrophils from leaving the cluster. This switch is believed to be caused by additional secretions of LTB4 and other chemoattractants within the neutrophil aggregates.
In stage 5, the swarming response terminates and the clusters dissolve with the resolution of inflammation. Little is known about the mechanisms of this stage but the process may be regulated by neutrophils or external factors from the tissue environment. In a laser-induced skin injury model, neutrophil aggregation typically stopped after 40–60 minutes which occurs at the same time as the appearance of secondary myeloid cell swarms. Knock-in mice studies have shown that the myeloid cells move slower than neutrophils and assemble around the neutrophil aggregates during this stage. These myeloid cells may disrupt the propagation signals of neutrophil chemoattractants or to create competing attractants in the tissue space so that the neutrophil aggregation is less strong.
External factors
When discussing the neutrophil swarming, it is important to address the other factors in the outside environment that can influence what is happening during migration of these neutrophils whether in packs or individually. A massive influence of neutrophils occurs when there is some sort of inflammatory problem occurring as they influence autocrine and paracrine signaling, involved in the clustering up and recruiting of the neutrophils themselves. Neutrophil swarming are influenced by three main external factors: type of tissues involved, nearby tissue-specific cells, and something referred to as chemoattractant (or when there is a chemical substance that influences a bacterium to move in the direction of their increasing concentration). One of the external factors that impact how communication occurs is the tissue context, as these each have a specific signal that can influence the swarming (the size and persistence of the neutrophil swarms). Two of these types are extravascular swarming and intravascular swarming. The extravascular swarming is due to integrin-independent interstitial movement as well as using soluble directional aspects like LTB4 that affects neutrophil attraction. Extravascular swarming consists of fibrillar (ex. skin) and cell rich (ex. lymph node) while intravascular consists of intrasinusoidal, with an example being the liver.
Swarming signals
Two triggers of neutrophil swarming include PAMPs or Pathogen Associated Molecular Patterns and DAMPs or Damage-Associated Molecular Patterns. One attribute of note in neutrophil swarming is that it is a conserved protective mechanism that respond when tissues undergo disruption. This can occur in many different tissues of the body includes the ears, liver, lung, and skin. The neutrophil warming can also participate in activating pathogen containment, keeping foreign substances localized and easier to treat and rid the body of later on.
In the figure above, we see that at the start of neutrophil swarming, we begin with either an injury, fungi, or bacteria. As discussed above the PAMPs and the DAMPs trigger the initial neutrophil swarming. Then the LTB4 and CXCL2, which are chemoattractants, that are there to further the signals that cause a cascade of intracellular reactions to the disruptions and foreign substances. These begin a process known as swarm aggregation where the bacterial or other substances begin to all congregate together into one massive "ball" of bacteria, as shown above after the second green arrow. Another part of the image includes the box above the LTB4 and CXCL2, including Calcium, complement, ATP, Connexin 43, and Integrins. These also contribute to the chemoattractants by amplifying their signal and causing the swarm aggregation to run more forwardly. However, below is the NADPH Oxidase 2 or NOX2 is a negative regulator of the chemoattractants that may disrupt the events from proceeding forward. These events previously show how neutrophil swarming begins while the steps ahead are going to explain the ending of this process once the body no longer needs this to occur for its health and well-being, if the bacteria fungi or injury has resolved. The most crucial step in terminating the neutrophil swarming is when GPCR kinase 2 or GRK2 has phosphorylated or desensitized the GPCRs (G-protein coupled receptors). Then the other three, Lipoxin A4, resolving E3, and w-OH-LTB4 assist the GRK2 in stopping this process fully.
Essential regulators of signaling
One of the regulators of signaling includes Calcium. It is one of the positive regulators to chemoattractants such as LTB4 and CXCL2. To obtain calcium, the cell must get the calcium from the intracellular endoplasmic reticulum (ER) or from the extracellular matrix. For the endoplasmic reticulum calcium sequestering, the cell uses a process called SOCE or store-operated calcium entry that induces cascades of signaling via receptors and these then stimulate the release of calcium out of the ER. In order to bring the Calcium from outside the cell a much more complex process occurs by using CRAC or calcium release-activated calcium channels (which also have something called ORAI family members in them). Before this can occur, however, stromal interaction molecule proteins (STIM) must detect the calcium and this then allows the ER to sense a change thus changing their shape and allowing these CRAC channels to gate between the intracellular ER and the extracellular space in order that calcium may be through into the cell then driving downstream mechanisms that were dependent on calcium. During swarming, neutrophils notably exhibit sustained calcium activity in the center of the swarm and produces calcium waves.
Another part of regulation includes the chemokines and the cytokines. There are two chemokines that work cooperatively in neutrophil swarming operations, CXCL2 and LTB4. They did tests in order to find out that CXCL2 did in fact assist, making a noticeable impact on the driving of swarming. But, it was a little more complicated than just that one chemokine. In coupling with inhibition of CXCR1 as well as BLT1 and BLT2 there was a decrease in chemoattractant inducement (also known as chemotactic index). In summary, there is a chemokine called CXCL8, which is basically a ligand of CXCR1 and 2 that alongside LTB4 positively promotes the swarming in neutrophils.
Basics of neutrophils
In order to properly understand neutrophil swarming, one must also understand the basics of the structure and function of neutrophils. They are leukocytes (white blood cells) that are the most abundant WBC in the body and are known for their role in the immune system.
In figure 2, it shows the main three ways in which a neutrophil can approach attacking and getting rid of a foreign antigen or bacteria. The top left illustrates degranulation, a process in which the neutrophil itself degradulates and then releases its substances in the outer circulation in which the bacteria lies. These contents work to destroy/break down the bacteria. The second way, on the upper right, shows phagocytosis. This is when the bacteria is brought into the neutrophil by the plasma membrane engulfing it and pulling it inside to create a vacuole. The engulfing process begins with a bacteria, then turns into a phagosome when it being to form a vacuole, and lastly becomes a phagolysosome that contain broken down bacteria with contents from the neutrophil environment inside. These contents have enzymes that degrade the bacteria coupled with a low pH of the internal environment. Lastly, in the bottom part of the image, it shows NETosis. Comparatively to the other bacteria, the bacteria are much larger and thus need this process to be combatted. It includes the creation of NETs or neutrophil extracellular traps that are composed of DNA wrapped around histones and proteins like myeloperoxidase and elastase. These DNA string extensions along with the helper proteins envelop the bacteria and these break down the bacteria. All three of these processes show the action that neutrophils have in targeting and destroying foreign substances, their main job in the body.
References
Cell biology | Neutrophil swarming | [
"Biology"
] | 3,864 | [
"Cell biology"
] |
54,447,677 | https://en.wikipedia.org/wiki/Pentafluorosulfanylbenzene | Pentafluorosulfanylbenzene, or phenylsulfur pentafluoride, is an organosulfur compound with the formula C6H5SF5. It is colorless liquid with high chemical stability.
Reactivity
Pentafluorosulfanylbenzene possesses high chemical stability under a wide range of conditions including oxidizing, reducing, strongly acidic and strongly basic environments. For example, it does not react with a refluxing solution of sodium hydroxide in aqueous ethanol, but it can react with concentrated sulfuric acid at elevated temperatures.
The pentafluorosulfanyl group is a strong electron withdrawing group, and leads to electrophilic aromatic substitution reactions at the meta position.
Synthesis
Pentafluorosulfanylbenzene was originally synthesized by fluorination of diphenyl disulfide by AgF2, a method that suffers from low yield. The best known method of synthesis is the fluorination of diphenyl disulfide with xenon difluoride, but it still only has a 25% yield.
References
Phenyl compounds
Organosulfur compounds
Sulfur fluorides | Pentafluorosulfanylbenzene | [
"Chemistry"
] | 247 | [
"Organic compounds",
"Organosulfur compounds"
] |
54,448,472 | https://en.wikipedia.org/wiki/Glasser%27s%20master%20theorem | In integral calculus, Glasser's master theorem explains how a certain broad class of substitutions can simplify certain integrals over the whole interval from to It is applicable in cases where the integrals must be construed as Cauchy principal values, and a fortiori it is applicable when the integral converges absolutely. It is named after M. L. Glasser, who introduced it in 1983.
A special case: the Cauchy–Schlömilch transformation
A special case called the Cauchy–Schlömilch substitution or Cauchy–Schlömilch transformation was known to Cauchy in the early 19th century. It states that if
then
where PV denotes the Cauchy principal value.
The master theorem
If , , and are real numbers and
then
Examples
References
External links
Integral calculus | Glasser's master theorem | [
"Mathematics"
] | 169 | [
"Integral calculus",
"Calculus"
] |
54,448,552 | https://en.wikipedia.org/wiki/NGC%207053 | NGC 7053 is a spiral galaxy located about 200 million light-years away in the constellation of Pegasus. It was discovered by astronomer Albert Marth on September 2, 1863. It was then rediscovered by astronomer Heinrich d'Arrest on October 8, 1865.
Tow supernovae have been observed in NGC 7053. On 4 June, 2003, SN 2003ep (type Ia, mag. 15.7) was discovered. On 28 July, 2022, SN 2022pux (type II, mag. 17.9) was discovered.
See also
NGC 7042
References
External links
Spiral galaxies
Pegasus (constellation)
7053
11727
66610
Astronomical objects discovered in 1863 | NGC 7053 | [
"Astronomy"
] | 140 | [
"Pegasus (constellation)",
"Constellations"
] |
54,449,666 | https://en.wikipedia.org/wiki/Semantic%20space | Semantic spaces in the natural language domain aim to create representations of natural language that are capable of capturing meaning. The original motivation for semantic spaces stems from two core challenges of natural language: Vocabulary mismatch (the fact that the same meaning can be expressed in many ways) and ambiguity of natural language (the fact that the same term can have several meanings).
The application of semantic spaces in natural language processing (NLP) aims at overcoming limitations of rule-based or model-based approaches operating on the keyword level. The main drawback with these approaches is their brittleness, and the large manual effort required to create either rule-based NLP systems or training corpora for model learning. Rule-based and machine learning based models are fixed on the keyword level and break down if the vocabulary differs from that defined in the rules or from the training material used for the statistical models.
Research in semantic spaces dates back more than 20 years. In 1996, two papers were published that raised a lot of attention around the general idea of creating semantic spaces: latent semantic analysis and Hyperspace Analogue to Language. However, their adoption was limited by the large computational effort required to construct and use those semantic spaces. A breakthrough with regard to the accuracy of modelling associative relations between words (e.g. "spider-web", "lighter-cigarette", as opposed to synonymous relations such as "whale-dolphin", "astronaut-driver") was achieved by explicit semantic analysis (ESA) in 2007. ESA was a novel (non-machine learning) based approach that represented words in the form of vectors with 100,000 dimensions (where each dimension represents an Article in Wikipedia). However practical applications of the approach are limited due to the large number of required dimensions in the vectors.
More recently, advances in neural network techniques in combination with other new approaches (tensors) led to a host of new recent developments: Word2vec from Google, GloVe from Stanford University, and fastText from Facebook AI Research (FAIR) labs.
See also
Word embedding
Semantic folding
Distributional–relational database
References
Semantics
Semantic relations
Natural language processing | Semantic space | [
"Technology"
] | 436 | [
"Natural language processing",
"Natural language and computing"
] |
54,449,949 | https://en.wikipedia.org/wiki/Kingmax | Kingmax is a Taiwan-based corporate group and manufacturer of RAM modules and memory cards. The principal company of the group is Kingmax Semiconductor Inc. was established in 1989, headquartered in Zhubei City, Hsinchu County, Taiwan, and the group manufactures and offers computer hardware and electronics products all over the world.
Overview
Originally, in 1989, Kingmax Semiconductor Inc. was established. The Group has several manufacturing facilities in Taiwan, China, and Hong Kong. The group manufactures and offers flash memory products (SD cards, USB flash drives and Solid state drives), Hard disk drives, DRAM, Card readers, USB adapters, and other electronics products all over the world. The business type and scope is same as ADATA, Silicon Power and Transcend Information, these are also the companies in Taiwan. In 2011, Kingmax was known that introduced the first 64GB microSD card in the world. In 2015, Kingpak Technology Inc. was merged into International Branding Marketing Inc. (English name is still Kingpak Technology Inc). And then, it was the first company of the group that changed status from private to public listed on the Taiwan OTC Market (6238.TWO). In 2017, Kingmax was also known that AirQ Check, the portable air quality checker for checking PM2.5 etc., received Taiwan Excellence Award.
In the aspect of business-to-business, as the supplier of computer hardware, Kingmax has contributed to offer the various products to major computer companies. The group has offered TinyBGA to IBM, hp, Sun Microsystems, Compaq, Dell, NEC, Acer, Asus
, CMOS image sensor to ON Semiconductor, etc. However, the group has been offered flash memory and DRAM by Lexar (Micron Technology) and Elixir (Nanya Technology).
Group Companies
Kingmax Semiconductor Inc. (勝創科技股份有限公司)
Kingmax Digital Inc. (協泰國際股份有限公司)
Kingpak Technology Inc. (勝麗國際股份有限公司)
See also
List of companies of Taiwan
References
External links
Official Website
Computer companies established in 1989
Computer hardware companies
Computer memory companies
Computer peripheral companies
Computer storage companies
Electronics companies of Taiwan
Taiwanese brands
Taiwanese companies established in 1989 | Kingmax | [
"Technology"
] | 474 | [
"Computer hardware companies",
"Computers"
] |
54,450,226 | https://en.wikipedia.org/wiki/Corallivore | A corallivore is an animal that feeds on coral. Corallivores are an important group of reef organism because they can influence coral abundance, distribution, and community structure. Corallivores feed on coral using a variety of unique adaptations and strategies. Known corallivores include certain mollusks, annelids, fish, crustaceans, flatworms and echinoderms. The first recorded evidence of corallivory was presented by Charles Darwin in 1842 during his voyage on HMS Beagle in which he found coral in the stomach of two Scarus parrotfish.
History
While visiting the Cocos (Keeling) Islands in 1842, Charles Darwin was told by an Englishman living on the islands that there were large shoals of parrotfish that subsisted entirely on coral. Darwin dissected several parrotfish and found pieces of coral and finely ground calcareous material in their stomach. This led Darwin to correctly theorize that some species of parrotfish consume coral and contribute sediment to the environment by passing finely ground particles from coral skeletons.
In 1952, the first descriptions of organisms actively consuming coral were written by Jacques Cousteau and published in National Geographic. During his trip to the Red Sea aboard RV Calypso, Cousteau swam with a pair of green humphead parrotfish and watched them take regular bites and leaving white scars on the coral around them. Like Darwin, Cousteau also noticed the sediment particles that were produced in the parrotfishs' waste and settled to the seafloor. Cousteau noted the leisurely speed with which the parrotfish consumed the coral and remarked that they appeared "unhurried" and like "sea cows, browsing on stone pastures."
The term "corallivore" comes from the Latin word for coral and -vora for to eat or devour.
Types
Approximately one-third of known corallivores are obligate corallivores, while the remaining three-fourths are facultative corallivores. Obligate corallivory is defined as having a diet which is at least 80% coral. Obligate corallivores are present in all tropical oceans, except the Caribbean. Facultative corallivores are defined as organisms that regularly consume coral without it comprising a large percentage of their diet.
It is thought that some facultative corallivores, such as some damselfish, eat coral to promote algal growth. Many facultative corallivores also graze on algae, which competes with coral for space and resources. By grazing coral, it may provide better conditions for algal growth. Aggressive grazing may keep the algal community in a state of accelerated growth, effectively preventing the transition to a slower growing community.
Feeding strategies
Organisms display different strategies for consuming coral. The majority of corallivores feed on stony coral, however, a few species feed on soft coral. There are no known obligate soft coral feeder; soft coral is estimated to be a small percentage of the diet of soft coral feeders. The most common genera of coral consumed are Acropora, Pocillopora, Montipora, and Porites. Only 18 out of the 111 described coral genera are known to be consumed by corallivores.
Mucus feeders
Mucus feeders feed exclusively on coral mucus. Coral regularly slough off mucus into the surrounding water, so it is thought that mucus feeding causes no harm to the coral. However, it has been shown to disrupt microbial communities living on the coral. Many mucus feeders have shown a preference towards damaged corals, which typically produce more mucus than undamaged corals.
Browsers
Browsers eat coral tissue without damaging the coral's calcium carbonate skeleton. The majority of corallivore species are browsers.
Scrapers
Scrapers consume live coral tissue and small portions of the coral's calcium carbonate skeleton.
Excavators
Excavators consume live coral tissue and large portions of the coral's calcium carbonate skeleton. Excavators can be further broken down to "spot biters" and "focused biters". Spot biters take bites that are scattered over a colony's surface, while focused biters bite repeatedly in the same area. At one time, focused biting was thought to be a display of territoriality in parrotfish, but was later determined to be for food. Out of all of the kinds of corallivores, excavators are thought to have the biggest impact on coral reef communities due to the large amount of coral and skeleton consumed. Additionally, studies suggest that the damage from excavating takes significantly longer to heal than other types of corallivory.
Bioeroders
Bioeroders consume dead coral substrate. Bioeroders are thought to help reshape coral reef landscapes by eroding dead corals.
In nature
Corallivory is relatively rare in nature; less than 3% of known fish species, four families of crustaceans, four families of gastropods, and a few echinoderm genera have been identified as corallivores. Corallivores are present in all tropical reef regions. The region with the highest proportion of corallivorous organisms is the tropical eastern Pacific Ocean.
Fish
Butterflyfish constitute a large percentage of the known corallivores; of the 128 known corallivorous fish species, 69 are butterflyfish species. Additionally, 50% of butterflyfish species are corallivores, making corallivory their most common feeding method. Corallivorous fish come from 11 different families. 39 species are obligate corallivores.
Butterflyfish have a wide range of adaptations that facilitate coral consumption. Some butterflyfish have long mouth that they use like forceps to pluck off individual coral polyps and some use their teeth to scrape off coral tissue. Butterflyfish that consume coral have longer intestines than fish that do not consume coral, suggesting that corallivores need more time to process the complex molecules of the coral.
The golden pufferfish is distributed widely across the tropical oceans, however, is considered a particularly significant corallivore, specifically in the tropical Eastern Pacific. The golden pufferfish uses its beak-like dental plate to feed on the tips of branching corals at an estimated pace of of calcium carbonate per of live coral per day. Despite the large amount of coral consumed, studies suggest that the golden pufferfish has little influence on coral abundance in the region.
Parrotfish are a family of fish that contain several corallivorous species. Reef-dwelling parrotfish have teeth on their lower and upper jaw that have evolved into an edge for cutting. This cutting edge allows parrotfish to scrape and feed on coral tissue and skeleton. The cutting edge on the teeth of parrotfish resembles a beak, which is the basis for the organism's common name. In addition to the cutting edge adaptation, parrotfish also have well-developed crossed joints that connect the dentary and articular bones of the lower jaw, which presents a mechanical advantage that makes the bite much stronger.
Invertebrates
There are 48 known corallivorous invertebrate species, 14 of which are obligate corallivores. The facultative corallivore crown-of-thorns star is an important coral browser that feeds by everting its stomach and using its tube feet to spread the stomach over the coral and into the crevices between polyps. Occurrences of high crown-of-thorns star population densities has resulted in documented decimation of large coral reef tracts, with reports of 100% coral mortality in localized areas. It is estimated that one crown-of-thorns star may eat up to of live coral per year.
The genus Drupella are obligate corallivorous sea snails that specialize on fast growing Acropora and Montipora species. Like crown-of-thorns star, Drupella aggregations have been known to destroy large areas of coral, and have been cited as the cause for instances of significant coral reduction in Toga Bay, Japan, and Ningaloo Reef, Australia.
Most corallivores display a preference for one or a few types of coral. However, the obligate corallivore snail, Coralliophila abbreviata, is known to feed on 26 different species of coral and shows no distinct preference for one species. C. abbreviata lacks a radula that would allow it to scrape off coral tissue, so coral is broken down by digestive enzymes.
Not all corallivores are detrimental to coral health. Corals with populations of the mucus feeding Tetralia and Trapezia crabs were shown to have a greater chance of survival during an crown-of-thorns star outbreak. Trapezia crabs are known to symbiotically benefit their host coral by cleaning sediment and debris off their surface.
Some organisms receive more than nutrition. The nudibranch, Phestilla sibogae, has been known to incorporate zooxanthellae, a phytoplankton symbiont, harvested through corallivory into its cerata. After they are incorporated, the zooxanthellae continue to photosynthesize and provide energy for the nudibranch.
Impacts on ecosystem
Corallivory often results in damage to coral or loss of coral biomass, and sometime directly causes coral death. Corals divert energy and resources towards repairing damage, which has shown to suppress additional growth. The ability for a coral to repair itself is partially based on the size of the lesion; since not all damage can be healed, superfluous damage can result in permanent change to the reef. Corals have shown to energetically prioritize repairing damage over reproducing, so corallivory can have a negative effect on coral reproduction. Additionally, studies have shown that grazing by corallivores can be associated with reduced zooxanthellae densities.
Scientists believe that excessive fishing of predators to corallivores, like large piscivorous fish, may result in an increase in corallivore abundance. This increase in corallivory may have a future negative effect on coral health and density.
Corallivory can indirectly cause an increase in growth of competitive organisms, such as algae and sponges. Additionally, some corallivores have been implicated in the spread of coral diseases. Some studies have shown that corallivores can have an influence on the competitive abilities of coral colonies.
Corallivory is not always detrimental to coral reefs. If the species of coral being consumed is spatially dominant, grazing can help control growth and promote greater reef diversity.
Corallivores are often sensitive to declines in coral health and population size, and are negatively affected during periods of high coral loss. In particular, obligate corallivores have been reported to experience high population declines following instances of coral loss. Studies have shown that corallivores suffer during bleaching events, suggesting that bleached coral is not as nutritional as healthy coral. Scientific investigation into the nutritional value of healthy and bleached coral is lacking. However, it has been determined that the disparity in nutritional value is not related to the concentration of zooxanthellae.
Known corallivores
This list contains the majority of known corallivores, as research is actively ongoing.
See also
Parrotfish
Pufferfish
Butterflyfish
Triggerfish
Wrasse
Damselfish
Acanthaster planci
Arothron meleagris
Architectonicidae
Epitoniidae
Pediculariidae
Muricidae
Drupella
Coralliophila
References
Marine animals
Animals by eating behaviors | Corallivore | [
"Biology"
] | 2,411 | [
"Ethology",
"Behavior",
"Animals by eating behaviors"
] |
54,450,566 | https://en.wikipedia.org/wiki/NGC%207056 | NGC 7056 is a barred spiral galaxy located about 225 million light-years away in the constellation of Pegasus. NGC 7056 was discovered by astronomer Albert Marth on September 17, 1863. It was then rediscovered by astronomer Truman Henry Safford on September 29, 1866.
See also
NGC 7051
References
External links
Barred spiral galaxies
Pegasus (constellation)
IC objects
7056
11734
66641
Astronomical objects discovered in 1863
Discoveries by Albert Marth | NGC 7056 | [
"Astronomy"
] | 91 | [
"Pegasus (constellation)",
"Constellations"
] |
54,451,462 | https://en.wikipedia.org/wiki/Preening | Preening is a found in birds that involves the use of the beak to position feathers, interlock feather that have become separated, clean plumage, and keep ectoparasites in check. Feathers contribute significantly to a bird's insulation, waterproofing and aerodynamic flight, and so are vital to its survival. Because of this, birds spend considerable time each day maintaining their feathers, primarily through preening. Several actions make up preening behaviour. Birds fluff up and shake their feathers, which helps to "rezip" feather barbules that have become unhooked. Using their beaks, they gather preen oil from a gland at the base of their tail and distribute this oil through their feathers. They draw each contour feather through their bill, nibbling it from base to tip.
Over time, some elements of preening have evolved to have secondary functions. Ritualised preening has become a part of some courtship displays, for example. It is also a displacement activity that can occur when birds are subjected to two conflicting drives. Though primarily an individual function, preening can be a social activity involving two or more birds – a behaviour known as allopreening. In general, allopreening occurs either between two members of a mated pair or between flock members in a social species. Such behaviour may assist in effective grooming, in the recognition of individuals (mates or potential sexual partners), or in reducing or redirecting potential aggressive tendencies in social species. Most allopreening is confined to the head and neck, smaller efforts being directed towards other parts of the body.
Ingestion of pollutants or disease-causing organisms during preening can lead to problems ranging from liver and kidney damage to pneumonia and disease transmission. Injury and infection can cause overpreening in caged birds, as can confining a bird with a dominant or aggressive cage mate.
Etymology
The use of the word preen to mean the tidying of a bird's feathers dates from Late Middle English. It appears to be a variant of the word prune; one now-obsolete definition of prune meant "anoint", based on the Latin ungere, which had the same meaning. This usage was combined with the Scottish and northern English dialect preen meaning "pierce" or "pin", due to the "pricking" action of the bird's beak during preening.
Importance
Preening is a maintenance behaviour used by all birds to care for their feathers. It is an innate behaviour; birds are born knowing the basics, but there is a learned component. Birds that are hand-reared without access to a role model have abnormalities in their preening behaviours. Despite spending considerable time in their efforts, they do not use proper techniques to groom effectively and may do a poor job overall as a result. Displaced feathers can cause birds considerable trouble; such feathers might become damaged, could interrupt the smooth flow of air over a flying bird, or might allow the bird's body heat to escape. Preening allows a bird to reposition such displaced feathers. There is evidence that filoplumes, specialised feathers buried under a bird's outer covering of contour feathers, help to signal when contour feathers have been displaced. Mechanoreceptors at the base of the filoplumes only fire when contour feathers are displaced or the filoplume moves. Preening enables birds to remove dirt and parasites from their plumage, and assists in the waterproofing of feathers. During moult, birds remove the sheaths from around their emerging pin feathers while preening.
Because feathers are critical to a bird's survival – contributing to insulation, waterproofing and aerodynamic flight – birds spend a great deal of time maintaining them. When resting, birds may preen at least once an hour. Studies on multiple species have shown that they spend an average of more than 9% of each day on maintenance behaviours, preening occupying over 92% of that time, though this figure can be significantly higher. Studies found that some gull species spent 15% of daylight hours during the breeding season preening, while another showed that common loons spent upwards of 25% of their day preening. In most of the studied species where the bird's sex could be determined in the field, males spent more time preening than females, though this was reversed in ducks. Some ratites, which are not dependent on their feathers for flight, spend far less time on maintenance behaviours. One study of ostriches found that they spent less than 1% of their time engaged in such behaviours.
Preen oil
Fully grown feathers are essentially dead structures, so it is vital that birds have some way to protect and lubricate them. Otherwise, age and exposure cause them to become brittle. To facilitate that care, many bird species have a preen or uropygial gland, which opens above the base of the tail feathers and secretes a substance containing fatty acids, water, and waxes. The bird gathers this substance on its bill and applies it to its feathers. The gland is generally larger (in relation to body size) in waterbirds, including terns, grebes and petrels. However, studies have found no clear correlation between the size of the gland and the amount of time a species spends in the water; it is not consistently largest in those species that spend the most time in the water.
Preen oil plays a role in reducing the presence of parasitic organisms, such as feather-degrading bacteria, lice and fungi, on a bird's feathers. One study of Eurasian hoopoes showed that the presence of symbiotic bacteria (Enterococcus faecalis) in their preen oil inhibited the growth of the feather-degrading bacteria Bacillus licheniformis. Enterococcus faecalis did this by releasing a bacteriocin. Female hoopoes transfer preen oil onto their brood patches and eggs, which results in the transfer of bacteria as well. Preen oil and bacteria are rubbed into microscopic pits on the surface of the eggs during incubation. This alters the colour of the eggs (darkening them) but there is also evidence that the bacteria may help to protect the developing chicks. Other studies have shown that removing or restricting access to the uropygial gland typically results in a higher bacterial parasite load on the plumage, though not necessarily of feather-degrading bacterial species. Preen oil may play a part in protecting at least some species from some internal parasites; a study of the incidence of avian malaria in house sparrows found that uninfected birds had larger uropygial glands and higher antimicrobial activity in those glands than infected birds did. There is even evidence that the foul-smelling preen oil of hoopoes and wood hoopoes may help to repel mammalian predators.
Preen oil helps to maintain the waterproofing of a bird's plumage. Though the oil does not provide any direct waterproofing agent, it helps to extend the life of the feather – including the microscopic structures (the barbs and barbules) which interlock to create the waterproof barrier.
While most species have a preen gland, the organ is missing in the ratites (emu, ostriches, cassowaries, rheas and kiwis) and some neognath birds, including bustards, woodpeckers, a few parrots and pigeons. Some species that lack a preen gland instead have powder down feathers which continually break down into a fine dust that the birds apply to their contour feathers while preening. These powder down feathers may be scattered throughout the bird's plumage or concentrated into dense patches. As well as helping to waterproof and preserve the bird's feathers, powder down can give a metallic sheen to the plumage.
Preening action
A bird's plumage is primarily made up of two feather types: firm vaned or pennaceous feathers on the surface, with softer down feathers underneath. Both feather types have a central shaft with narrower branching from that shaft. Pennaceous feathers also have much smaller barbules branching from the entire length of each barb; these barbules have tiny hooks along their length, which interlock with the hooks of neighbouring barbules. Barbules can become unhooked as a result of a bird's daily activities – dislodged when the bird brushes up against vegetation, for instance, or when it interacts with another bird during fighting or mating. Preening may involve two kinds of bill actions: nibbling (or mandibulating) while working the feather from base to tip, or stroking with the bill either open or closed. The nibbling action is the one used most often; it is more effective than stroking for applying preen oil, removing ectoparasites, rejoining unzipped barbules, and rearranging feathers. The stroking action is typically done in the direction the feathers lie, with the bill either opened or closed. Stroking is used to apply preen oil, as well as to dry and smooth plumage. Grebes stroke more vigorously with an open bill – a behaviour known as "stropping". Penguins use their whole heads to stroke, in a motion referred to as "wiping". Birds regularly fluff up their plumage and repeatedly shake their bodies while preening. Experiments have shown that the shaking action can "rezip" a majority of split feather barbules.
Birds cannot use their beaks to apply preen oil to their own heads. Instead, many use their feet in an action called scratch-preening. Once they have gathered preen oil on their beak, they scrape a foot across their bill to transfer the oil, and then scratch the oil into the feathers on their head. Longer-necked birds may rub their head directly on their uropygial gland. Some species (including nightjars, herons, frigatebirds, owls and pratincoles) have comb-like serrations on the claw (a pectinate claw) of the middle toe which may aid in scratch-preening. Some species stretch their leg over their lowered wing to reach their head (known as "indirect" scratching), while others extend their leg between their wing and their body (known as "direct" scratching). There is some evidence that the method used by a species may be related to its ecology. For instance, New World warblers that are primarily arboreal tend to be overwing scratchers, while those that spend significant time on the ground are typically underwing scratchers. In general, preening takes place while the bird is perched, on the ground, or swimming, but some of the more aerial species (including swifts, swallows, terns and albatrosses) preen while flying. Many birds have a slight overhang at the tip of their upper mandible. Experiments suggest that this allows birds to apply shearing forces that kill the flat-bodied feather lice; the removal of the bill tip caused an increase in feather lice due to ineffective preening.
Preening is often done in association with other maintenance behaviours, including bathing, dusting, sunning, oiling or anting, and can either precede or follow these other behaviours. All birds typically preen after bathing. Groups of birds sometimes all groom individually at the same time. This has been seen in species ranging from herons to blackbirds.
Secondary functions
Preening may help to send sexual signals to potential mates because plumage colouration (which can be altered by the act of preening) can reliably reflect the health or "quality" of its bearer. In some species, preen oil is used to cosmetically colour the plumage. During the breeding season, the preen oil of the great white pelican becomes red-orange, imparting a pink flush to the bird's plumage. The preen oil of several gull and tern species, including Ross's gull, contains a pink colourant which does the same. The heads of these birds typically show little pink, because of the difficulty of reaching those areas with preen oil. The yellow feathers of the great hornbill are also cosmetically coloured during preening. The preen oil of the Bohemian waxwing increases the UV reflectance of its feathers. Ritualised preening is used in courtship displays by several species, particularly ducks; such preening is typically designed to draw attention to a modified structure (such as the sail-shaped secondaries of the drake mandarin duck) or distinctive colour (such as the ) on the bird. Mallards of both sexes will lift a wing so that the brightly coloured speculum is showing, then will place their bill behind the speculum as if preening it. Courtship preening is more conspicuous than is preening for feather maintenance, using more stereotypical movements.
Preening may be performed as a displacement activity. In some cases, it is done in place of another activity that birds are strongly motivated, but unable, to do. In one study, black-headed gulls which were prevented from incubating a full clutch of eggs (by the removal of eggs from their nest) responded by preening and nest building – both displacement activities. When all three eggs in their regular clutch were removed, the gulls showed a significant increase in the amount of time they spent preening. The conflict between two incompatible drives, such as incubating and escape, can lead a bird to engage in displacement activities. Nesting Sandwich and common terns preen when they have been alarmed by a potential predator or when they have had an aggressive encounter with a neighbouring bird, for instance. Fighting European starlings will break off their battles to preen.
Allopreening
Although preening is primarily an individual behaviour, some species indulge in allopreening, one individual preening another. It is not particularly common among birds, though species from at least 43 families are known to engage in the mutual activity. Most allopreening activity concentrates on the head and neck, a lesser amount being directed towards the and and an even smaller percentage applied to the . A few species are known to allopreen other areas, including the rump, tail, belly and underwing.
Several hypotheses have been advanced to explain the behaviour: that it assists in effective grooming, that it assists in recognition of individuals (mates or potential sexual partners), and that it assists in social communication, reducing or redirecting potential aggressive tendencies. These functions are not mutually exclusive. Evidence suggests that different species may participate for different reasons, and that those reasons may change depending on the season and the individuals involved. In most cases, allopreening involves members of the same species, although some cases of interspecific allopreening are known; the vast majority of these involve icterids, though at least one instance of mutual grooming between a wild black vulture and a wild crested caracara has been documented. Birds seeking allopreening adopt specific, ritualised postures to signal so; they may fluff their feathers out or put their heads down. Captive birds of social species that normally live in flocks, such as parrots, will regularly solicit preening from their human owners.
There is some evidence that allopreening may help to keep in good condition those feathers that a bird cannot easily reach by itself; allopreening activities tend to focus on the head and neck. It may also help to remove ectoparasites from those hard-to-reach areas. Allopreening is most common among species that are regularly in close physical contact due to flocking or social behaviours, where such contact allows for easier transfer of ectoparasites between individuals. In one study, Macaroni penguins that frequently allopreened had significantly fewer ticks on their heads and necks than those that did not. Green wood hoopoes, a flocking species with a complex hierarchy, show similar frequencies of initiating and reciprocating allopreening of the head and neck regardless of social status, time of year or group size, which suggests that such activity is primarily related to feather hygiene.
Most allopreening is done between the two members of a mated pair, and the activity appears to play an important role in strengthening and maintaining pair bonds. It is more common in species where both parents help to raise the offspring and correlates with an increased likelihood that partners will remain together for successive breeding seasons. Allopreening often features as part of the "greeting ceremony" between the members of a pair in species such as albatrosses and penguins, where partners may be separated for a relatively long period of time, and is far more common among sexually monomorphic species (that is, species where the sexes look outwardly similar). It appears to inhibit or redirect aggression, as it is typically the dominant bird that initiates the behaviour.
Allopreening appears to reduce the incidence of conflict between members of some colonially living or colonially nesting species. Neighbouring common guillemots that engaged in allopreening were much less likely to fight. Since fights often lead to eggs or chicks being knocked off breeding cliffs, fewer fights led to greater breeding success for allopreening neighbours. Among social flocks of green wood hoopoes, rates of body allopreening (that is, allopreening of another bird's body rather than head and neck) increase with group size. Evidence suggests this type of allopreening reduces social tension, and thus plays an important role in group cohesion. More dominant birds receive far more body allopreening services than do lower-ranked birds, and lower-ranked birds initiate far more body allopreening bouts than do their higher-ranked flock mates. Body allopreening is only reciprocal when done between members of a mated pair; otherwise, the dominant bird reciprocates in fewer than 10% of the instances.
Potential problems
If birds are exposed to some pollutants, such as leaking petroleum, they can quickly lose the preen oil from their feathers. This causes a loss of heat regulation and waterproofing, and rapidly leads to the bird becoming chilled. If waterbirds are exposed, they can lose both buoyancy and the ability to fly; this means they must swim constantly to stay warm and afloat (if they cannot reach land), and eventually die of exhaustion. While preening in an effort to clean themselves, they may ingest harmfully large amounts of the petroleum. Ingested oil can cause pneumonia, as well as liver and kidney damage. Studies done with black guillemots showed that even small amounts of ingested oil caused the birds physiological distress. It interfered with the foraging efficiency of adults and decreased the growth rates of young birds.
Allopreening may facilitate disease transmission between infected and non-infected individuals. West Nile virus has been found in the feather pulp of several species of corvid, for instance, meaning that birds that preen infected partners might become infected themselves. Even preening its own body may expose a bird to pathogens. There is evidence that water-borne avian influenza virus is "captured" by the preen oil on feathers, providing a possible route for infection. The ingestion of parasites during preening may result in infection; the tick-borne disease louping ill virus can be transmitted to red grouse if the bird consumes a tick carrying the disease.
Caged birds, particularly parrots, sometimes overpreen in response to being exposed to strong scents (such as nicotine or air fresheners) or as a result of neuropathy. Reducing exposure to the offending odour, or treating the underlying cause of the neuropathy (such as injury, infection, or heavy metal intoxication) can help to eliminate the behaviour. Confining a bird with an incompatible or very dominant cage mate can lead to excessive allopreening, which can result in feather plucking or injury.
References
Works cited
External links
Barred owl preening on YouTube
Splendid fairy-wrens preening and allopreening on YouTube
Bird behavior
Feathers
Hygiene
Articles containing video clips | Preening | [
"Biology"
] | 4,164 | [
"Behavior by type of animal",
"Behavior",
"Bird behavior"
] |
60,841,429 | https://en.wikipedia.org/wiki/Angus%20McLaren%20%28historian%29 | Angus McLaren (December 20, 1942 – June 7, 2024) was a Canadian historian who was a professor of history at the University of Victoria in British Columbia, specializing in the history of sexuality.
McLaren was born in East Vancouver and earned a bachelor of arts from the University of British Columbia in 1965. He later earned two degrees from Harvard University, a master of arts in 1966 and a PhD in 1971.
In 1999, McLaren was named a fellow of the Royal Society of Canada.
After suffering from Parkinson's disease, McLaren died in June 2024, at the age of 81.
Selected publications
References
1942 births
2024 deaths
Academic staff of the University of Victoria
Historians of sexuality
University of British Columbia alumni
Harvard University alumni
Fellows of the Royal Society of Canada | Angus McLaren (historian) | [
"Biology"
] | 153 | [
"Behavior",
"Sexuality",
"Historians of sexuality"
] |
60,841,716 | https://en.wikipedia.org/wiki/APBS%20%28software%29 | APBS (previously also Advanced Poisson-Boltzmann Solver) is a free and open-source software for solving the equations of continuum electrostatics intended primarily for the large biomolecular systems. It is available under the BSD license.
PDB2PQR prepares the protein structure files from Protein Data Bank for use with APBS. The preparation steps include, but aren't limited to adding missing heavy atoms to the structures and assigning charges from a number of force fields. The output file format is PQR and that's where the name of the software comes from.
References
External links
Official documentation
APBS, PDB2PQR, and related software - GitHub
Molecular modelling software
Free and open-source software
Free software programmed in Python
Free software programmed in C++
Free software programmed in C | APBS (software) | [
"Chemistry"
] | 173 | [
"Molecular modelling software",
"Molecular physics",
"Computational chemistry software",
"Molecular modelling",
"Molecular physics stubs"
] |
60,841,839 | https://en.wikipedia.org/wiki/The%20Land%20Trust | The Land Trust is a British charity, based in Warrington, Cheshire, which owns or manages open spaces restored from derelict land for public benefit. Its vision is "to improve the quality of people’s lives by creating sustainable, high quality green spaces that deliver environmental, social and economic benefits".
The Land Restoration Trust was created in 2004 to ensure that restoration projects for derelict land would have a long-term future. It became independent as The Land Trust in 2009/10.
Projects
the Land Trust owns or manages more than in more than 50 spaces in England, and is developing projects in Scotland.
Spaces include:
Northumberlandia, a land sculpture near Cramlington, Northumberland
Phoenix Park, Thurnscoe, on the former Hickleton Main Colliery in South Yorkshire
Braeburn Park, a nature reserve in London Borough of Bexley
The Land Trust is working with Buglife in a project to conserve pollinating insects, initially on the trust's Yorkshire sites.
References
Further reading
External links
Charities based in Cheshire
Environmental charities based in the United Kingdom
Ecological restoration | The Land Trust | [
"Chemistry",
"Engineering"
] | 212 | [
"Ecological restoration",
"Environmental engineering"
] |
60,842,586 | https://en.wikipedia.org/wiki/NGC%203741 | NGC 3741 is an irregular galaxy in the constellation Ursa Major. It was discovered by John Herschel on March 19, 1828. At a distance of about 10 million light-years (3.2 Mpc), it is located in the M94 Group. It is relatively undisturbed by other galaxies.
NGC 3741 is an unusual galaxy in several aspects. It has a disk of neutral hydrogen (H I) that is extremely wide, extending some 23,000 light-years (7 kpc). The disk is strongly but symmetrically warped. With a mass-to-light ratio of MT/LB ~ 149, it is highly rich in dark matter.
NGC 3741 has a central bar and a faint spiral arm rich in H I. The bar rotates slowly, likely due to interaction with the dark matter. The bar and spiral arms would make NGC 3741 a low-luminosity spiral galaxy. The unusual properties could be explained if NGC 3741 were a late-stage merger between a low-mass companion or if it accreted mass from the intergalactic medium.
References
External links
3741
07768
Ursa Major
Irregular galaxies
035878
M94 Group | NGC 3741 | [
"Astronomy"
] | 249 | [
"Ursa Major",
"Constellations"
] |
60,842,665 | https://en.wikipedia.org/wiki/Back%20to%20nature | Back to nature or return to nature is a philosophy or style of living which emphasises closeness to nature, rather than artifice and civilisation. In this, the rustic customs and pastoralism of country life are preferred to urban fashion and sophistication.
At the end of the nineteenth century, a variety of back to nature movements developed in Germany which were collectively known as Lebensreform (life reform). These included naturism and naturopathy.
Notable exponents
Diogenes and other cynics who advocated the simple, shameless lifestyle of a dog
Henry David Thoreau, who spent two years living a simple life in a log cabin at Walden Pond
John Zerzan, an anarcho-primitivist who thinks that symbolic culture such as language is a barrier to the direct experience of nature
Ted Kaczynski, a mathematician who opposed industrial society as the Unabomber
See also
Back-to-the-land movement
Rewilding (conservation biology)
References
Nature
Philosophy of life
Simple living
Environmental philosophy | Back to nature | [
"Environmental_science"
] | 214 | [
"Environmental philosophy",
"Environmental social science"
] |
60,842,845 | https://en.wikipedia.org/wiki/Enumeration%20algorithm | In computer science, an enumeration algorithm is an algorithm that enumerates the answers to a computational problem. Formally, such an algorithm applies to problems that take an input and produce a list of solutions, similarly to function problems. For each input, the enumeration algorithm must produce the list of all solutions, without duplicates, and then halt. The performance of an enumeration algorithm is measured in terms of the time required to produce the solutions, either in terms of the total time required to produce all solutions, or in terms of the maximal delay between two consecutive solutions and in terms of a preprocessing time, counted as the time before outputting the first solution. This complexity can be expressed in terms of the size of the input, the size of each individual output, or the total size of the set of all outputs, similarly to what is done with output-sensitive algorithms.
Formal definitions
An enumeration problem is defined as a relation over strings of an arbitrary alphabet :
An algorithm solves if for every input the algorithm produces the (possibly infinite) sequence such that has no duplicate and if and only if . The algorithm should halt if the sequence is finite.
Common complexity classes
Enumeration problems have been studied in the context of computational complexity theory, and several complexity classes have been introduced for such problems.
A very general such class is EnumP, the class of problems for which the correctness of a possible output can be checked in polynomial time in the input and output. Formally, for such a problem, there must exist an algorithm A which takes as input the problem input x, the candidate output y, and solves the decision problem of whether y is a correct output for the input x, in polynomial time in x and y. For instance, this class contains all problems that amount to enumerating the witnesses of a problem in the class NP.
Other classes that have been defined include the following. In the case of problems that are also in EnumP, these problems are ordered from least to most specific:
Output polynomial, the class of problems whose complete output can be computed in polynomial time.
Incremental polynomial time, the class of problems where, for all i, the i-th output can be produced in polynomial time in the input size and in the number i.
Polynomial delay, the class of problems where the delay between two consecutive outputs is polynomial in the input (and independent from the output).
Strongly polynomial delay, the class of problems where the delay before each output is polynomial in the size of this specific output (and independent from the input or from the other outputs). The preprocessing is generally assumed to be polynomial.
Constant delay, the class of problems where the delay before each output is constant, i.e., independent from the input and output. The preprocessing phase is generally assumed to be polynomial in the input.
Common techniques
Backtracking: The simplest way to enumerate all solutions is by systematically exploring the space of possible results (partitioning it at each successive step). However, performing this may not give good guarantees on the delay, i.e., a backtracking algorithm may spend a long time exploring parts of the space of possible results that do not give rise to a full solution.
: This technique improves on backtracking by exploring the space of all possible solutions but solving at each step the problem of whether the current partial solution can be extended to a partial solution. If the answer is no, then the algorithm can immediately backtrack and avoid wasting time, which makes it easier to show guarantees on the delay between any two complete solutions. In particular, this technique applies well to self-reducible problems.
Closure under set operations: If we wish to enumerate the disjoint union of two sets, then we can solve the problem by enumerating the first set and then the second set. If the union is non disjoint but the sets can be enumerated in sorted order, then the enumeration can be performed in parallel on both sets while eliminating duplicates on the fly. If the union is not disjoint and both sets are not sorted then duplicates can be eliminated at the expense of a higher memory usage, e.g., using a hash table. Likewise, the cartesian product of two sets can be enumerated efficiently by enumerating one set and joining each result with all results obtained when enumerating the second step.
Examples of enumeration problems
The vertex enumeration problem, where we are given a polytope described as a system of linear inequalities and we must enumerate the vertices of the polytope.
Enumerating the minimal transversals of a hypergraph. This problem is related to monotone dualization and is connected to many applications in database theory and graph theory.
Enumerating the answers to a database query, for instance a conjunctive query or a query expressed in monadic second-order. There have been characterizations in database theory of which conjunctive queries could be enumerated with linear preprocessing and constant delay.
The problem of enumerating maximal cliques in an input graph, e.g., with the Bron–Kerbosch algorithm
Listing all elements of structures such as matroids and greedoids
Several problems on graphs, e.g., enumerating independent sets, paths, cuts, etc.
Enumerating the satisfying assignments of representations of Boolean functions, e.g., a Boolean formula written in conjunctive normal form or disjunctive normal form, a binary decision diagram such as an OBDD, or a Boolean circuit in restricted classes studied in knowledge compilation, e.g., NNF.
Connection to computability theory
The notion of enumeration algorithms is also used in the field of computability theory to define some high complexity classes such as RE, the class of all recursively enumerable problems. This is the class of sets for which there exist an enumeration algorithm that will produce all elements of the set: the algorithm may run forever if the set is infinite, but each solution must be produced by the algorithm after a finite time.
References
Algorithms | Enumeration algorithm | [
"Mathematics"
] | 1,279 | [
"Algorithms",
"Mathematical logic",
"Applied mathematics"
] |
60,842,892 | https://en.wikipedia.org/wiki/Phyllary | In botanical terminology, a phyllary, also known an involucral bract or tegule, is a single bract of the involucre of a composite flower. The involucre is the grouping of bracts together. Phyllaries are reduced leaf-like structures that form one or more whorls immediately below a flower head.
Function
Phyllaries provide protection to developing flowers and fruits. In the dandelion hybrid Taraxacum japonicum × officinale, recurved phyllaries help defend the flowers from herbivory by slugs.
They sometimes assist in the dispersal of fruits. The hooked phyllaries of burdock species (Arctium) cling to the fur and feathers of animals, dispersing the seeds away from the parent plant (exozoochory).
Structure and arrangement
Phyllary morphology is useful in plant identification as between species of the Asteraceae family, they may vary in number, shape, width, length, hairiness, presence of glands, or texture.
References
Plant morphology
Flowers | Phyllary | [
"Biology"
] | 227 | [
"Plant morphology",
"Plants"
] |
60,843,293 | https://en.wikipedia.org/wiki/PLUMED | PLUMED is an open-source library implementing enhanced-sampling algorithms, various free-energy methods, and analysis tools for molecular dynamics simulations. It is designed to be used together with ACEMD, AMBER, DL_POLY, GROMACS, LAMMPS, NAMD, OpenMM, ABIN, CP2K, i-PI, PINY-MD, and Quantum ESPRESSO, but it can also be used together with analysis and visualization tools VMD, HTMD, and OpenPathSampling.
In addition, PLUMED can be used as a standalone tool for analysis of molecular dynamics trajectories. A graphical user interface named METAGUI is available.
Collective variables
PLUMED offers a large collection of collective variables that serve as descriptions of complex processes that occur during molecular dynamics simulations, for example angles, positions, distances, interaction energies, and total energy.
References
External links
METAGUI
Molecular dynamics software
Computational biology
Free software programmed in C++
Free and open-source software
Software using the GNU Lesser General Public License | PLUMED | [
"Chemistry",
"Biology"
] | 211 | [
"Molecular dynamics software",
"Molecular physics",
"Computational chemistry software",
"Molecular dynamics",
"Computational biology",
"Molecular physics stubs"
] |
60,843,438 | https://en.wikipedia.org/wiki/Artemis%20V | Artemis V is the fifth planned mission of NASA's Artemis program and the first crewed flight of the Blue Moon lander. The mission will launch four astronauts on a Space Launch System rocket and an Orion to the Lunar Gateway and will be the third lunar landing of the Artemis program. In addition, Artemis V will also deliver two new elements to the Gateway Space Station.
Overview
Artemis V will launch four astronauts to the Lunar Gateway space station. The mission will deliver the European Space Agency's ESPRIT refueling and communications module and a Canadian-built robotic arm system for the Gateway. Also delivered will be NASA's Lunar Terrain Vehicle.
After docking to the Gateway, two astronauts will board the Blue Moon lunar lander and fly it down to the Lunar south pole to land near the Lunar Terrain Vehicle. This will be the first lunar landing since Apollo 17 to use an unpressurized lunar rover. It is planned to have the two astronauts on the surface of the Moon for about one week where they will conduct science and exploration activities.
, Artemis V is scheduled to launch no earlier than March 2030.
Spacecraft
Space Launch System
The Space Launch System is a super-heavy-lift launcher used to launch the Orion spacecraft from Earth to a trans-lunar orbit.
Orion
Orion is the crew transport vehicle used by all Artemis missions. It will transport the crew from Earth to the Gateway orbit, and return them to Earth.
Gateway
Gateway is a small modular space station to be established in Near-rectilinear halo orbit (NRHO) in late 2024. The first two Gateway elements will launch together aboard a SpaceX Falcon Heavy rocket in late 2024. The I-Hab habitat module will be delivered by Artemis IV.
Blue Origin's Blue Moon lander
The Blue Moon lander will transfer astronauts from the Gateway to the Lunar surface and back. Blue Origin will be the second provider to deliver Artemis astronauts to the lunar surface. NASA previously contracted SpaceX to develop and demonstrate the Starship Human Landing System.
Blue Origin will design, develop, test, and verify its Blue Moon lander to meet NASA's human landing system requirements for recurring astronaut expeditions to the lunar surface. In addition to design and development work, the contract includes one uncrewed demonstration mission to the lunar surface and the crewed demo in 2030. The total award value of the contract is $3.4 billion.
Lunar Terrain Vehicle
The Lunar Terrain Vehicle is an unenclosed rover being developed by NASA that astronauts will drive on the Moon while wearing spacesuits.
See also
List of Artemis missions
List of missions to the Moon
References
External links
Orion website at nasa.gov
Space Launch System website at nasa.gov
2029 in spaceflight
Artemis program
Crewed missions to the Moon
Orion (spacecraft)
Space Launch System
2029 in the United States
Missions to the Moon
Crewed spacecraft
Future human spaceflights
Lunar Gateway
Spaceflight
Space stations | Artemis V | [
"Astronomy"
] | 588 | [
"Spaceflight",
"Outer space"
] |
60,844,791 | https://en.wikipedia.org/wiki/Austempered%20Ductile%20Iron | Austempered Ductile Iron (ADI) is a form of ductile iron that enjoys high strength and ductility as a result of its microstructure controlled through heat treatment. While conventional ductile iron was discovered in 1943 and the austempering process had been around since the 1930s, the combination of the two technologies was not commercialized until the 1970s.
Microstructure
Like all ductile iron, ADI is characterized by its spheroidal graphite nodules spaced within the matrix. These nodules reduce microsegregation of solutes within the material. For ADI, the material has been austempered such that the matrix is transformed into ausferrite, or a mixture of acicular ferrite and austenite. The microstructure is used to classify ADI into grades, which depend on the heat treatment process and not the composition of the material.
Mechanical properties
The high strength and ductility of ADI are a direct result of its microstructure. Specifically, the ductility of ductile irons is a result of the lack of bainite in the matrix. Rather, the austempering process forms acicular ferrite and austenite. The latter of these has a face-centered cubic (FCC) structure. The FCC has 12 slip systems that allow for dislocations motion, resulting in high ductility in the austenitic phase of ADI. This ductility also translates to relatively high toughness in ADI.
The increase in ductility that ADI exhibits over other form of cast iron also comes as a result of the spheroidal graphite. As compared to the flake-like graphite present in gray iron, for example, the spheroidal graphite nodes are relatively easy for dislocations to bypass, increasing the ductility of the material. These nodules also decrease the stress concentration compared to flakes, as stress at the tip of an inclusion is proportional to the radius of curvature. The large radius prevents the propagation of cracks in the material, further resulting in high ductility and good fatigue properties in the material.
Some of the austenite phase mentioned above is mechanically metastable and will form martensite when subjected to high stress. The combination of hard, wear-resistant martensite with ausferrite results in good wear properties, as the regions near a crack tip strengthen and prevent further propagation. This is not an example of work hardening, which multiplies dislocations that inhibit each other's growth and result in higher strength. Rather, a phase transformation is taking place as a result of applied stress.
The mechanical properties of ADI are extremely dependent on processing. Wide ranges in strength and ductility are possible. High temperature heat treatment (>400C) results in high ductility, good impact toughness, with a yield strength around 500 MPa. Lower temperatures (~260C) results in a higher yield strength of 1400 MPa and high hardness but much lower ductility.
References
Ferrous alloys | Austempered Ductile Iron | [
"Chemistry"
] | 616 | [
"Ferrous alloys",
"Alloys"
] |
60,844,836 | https://en.wikipedia.org/wiki/Nintendo%20Gateway%20System | The Nintendo Gateway System is a series of video game consoles specialized for airlines and hotels. As part of a partnership between Nintendo and LodgeNet from late 1993 up until the late 2000s, about 40,000 airline seats and 955,000 hotel rooms featured a modified version of the Super Nintendo Entertainment System, Game Boy, Game Boy Color, Game Boy Advance, Nintendo 64, or GameCube, installed on some Northwest, Singapore Airlines, Air China, Air Canada, Alitalia-Linee Aeree Italiane, All Nippon Airways, British Midland International, Kuwait Airways, Malaysia Airlines, Thai Airways, and Virgin Atlantic passenger aircraft, as well as certain hotels with LodgeNet, NXTV, or Quadriga entertainment systems.
Aimed at adults than Nintendo's core children's market, it was one of the first in-seat airline entertainment services, provided by Matsushita Avionics, Rockwell Collins, and Thales Avionics. The controller, or remote, for the airline version of the Gateway System had a button setup similar to the Super NES controller, and it also doubled as a remote for the movie and music aspects of the system. It was part of a much larger computer system that allowed air passengers to not only play video games, but also watch movies and shows, listen to music, talk on the phone, and even shop while in-flight, before the rise of the internet. Upon its release, there were 10 games installed in the system, which included The Legend of Zelda: A Link to the Past, F-Zero and Super Mario World. Future plans for the system were to have it installed on cruise ships as well.
LodgeNet partnered with Nintendo to bring video games directly into guest hotel rooms through streaming over the LodgeNet server, with the special LodgeNet controller plugging directly into the TV or LodgeNet set-top box, transmitting the game over phone lines connected to a central game server. Pricing was usually $6.95 plus tax for 1 hour of video games. After 1 hour, the game would immediately stop and prompt the user to purchase more play time. Many games were modified for single-player play only.
Its official website was discontinued in mid-2008, but units have been seen as late as 2013 for Nintendo 64 in hotels, and as late as 2012 for Game Boy and Game Boy Color on Singapore Airlines. LodgeNet was the most widespread pay-per-view system for hotels that used it.
History
On August 10, 1993, Nintendo of America began rolling out the Nintendo Gateway System, initially in one of Northwest Airlines' Boeing 747 and LodgeNet.
In late 1993, LodgeNet launched its on-demand hospitality service, including worldwide delivery of Super NES games to hotel guests via its proprietary building-wide networks. LodgeNet eventually reported the system being installed in 200,000 hotel guest rooms by April 1996, and 530,000 guest rooms by mid-1999. By April 1996, LodgeNet reported that its partnership with Nintendo to deliver Super NES games had yielded 200,000 worldwide hotel guest room installations. In June 1998, Nintendo and LodgeNet entered a 10-year licensing agreement for an "aggressive" upgrade to add Nintendo 64 support to their existing 500,000 Super NES equipped guest room installations. LodgeNet says that within the system's previous five years to date, the system had "caused Nintendo to become the most successful new product rollout in the history of the hotel pay-per-view industry". LodgeNet reported that within the middle of 1998 alone, 35 million hotel guests encountered the Nintendo name as an integral amenity, and it reported sales of more than 54 million minutes of Nintendo-based gameplay.
In June 1999, LodgeNet and Nintendo began expanding and upgrading their existing Super NES buildout to include Nintendo 64 support. In mid-1999, LodgeNet reported that its 530,000 hotel room installations were increasing at a rate of 11,000 rooms per month. In September 2000, Nintendo and LodgeNet began delivering newly released Nintendo 64 games to hotel rooms at more than 1,000 hotel sites, concurrently with the games' retail releases, demonstrating "the capacity to update LodgeNet's interactive digital systems with fresh content virtually overnight".
Games
Games are offered for six Nintendo platforms, the Super Nintendo Entertainment System, the Game Boy, the Game Boy Color, the Game Boy Advance, the Nintendo 64, and the GameCube, with support for the Nintendo Entertainment System planned. While GB, GBC, and GBA games are exclusive to the airlines, the N64 and GC games are exclusive to the hotels, and the SNES is available for both.
Super Nintendo Entertainment System
There were 49 Super Nintendo Entertainment System titles available to play on LodgeNet hotel televisions and on airlines equipped with Nintendo Gateway System, which LodgeNet used for their hotel service. Some titles were not playable on airlines.
Blackthorne
Boogerman: A Pick and Flick Adventure (not available on airlines)
Boxing Legends of the Ring
The Brainies
ClayFighter: Tournament Edition (not available on airlines)
ClayFighter 2: Judgment Clay (not available on airlines)
Claymates
Donkey Kong Country
Donkey Kong Country 2: Diddy's Kong Quest (not available on airlines)
Dr. Mario (standalone, exclusive to the service)
Final Fight
F-Zero
Hagane: The Final Conflict
Hal's Hole in One Golf
Hangman (exclusive to the service)
Killer Instinct (not available on airlines)
Kirby's Dream Course
The Legend of Zelda: A Link to the Past
The Lost Vikings
The Lost Vikings 2
Mega Man X
NCAA Basketball (listed in a Nintendo Power article about the Gateway Service, unknown availability)
Noughts & Crosses (exclusive to the service)
Panel de Pon
Postcard Puzzle (exclusive to the service)
Prehistorik Man
Pro Mahjong Kiwame
Shanghai II: Dragon's Eye
Street Fighter II: The World Warrior
Street Fighter II: Hyper Fighting (not available on airlines)
Super Adventure Island
Super Bonk
Super Ghouls 'n Ghosts
Super Mario All-Stars
Super Mario All-Stars + Super Mario World (unknown availability)
Super Mario World
Super Metroid (not available on airlines)
Super Play Action Football
Super Punch-Out!!
Super Soccer
Super Solitaire
Super Street Fighter II (not available on airlines)
Super Tennis
True Golf Classics: Pebble Beach Golf Links (listed in a Nintendo Power article about the Gateway Service, unknown availability)
Tetris (standalone, exclusive to the service)
Tetris Attack
Tetris & Dr. Mario
Vegas Stakes
Wario's Woods
Nintendo 64
There were 38 Nintendo 64 titles available to play on LodgeNet hotel televisions.
1080° Snowboarding
Donkey Kong 64
Dr. Mario 64
Excitebike 64
Extreme-G
F-Zero X
Forsaken 64
Gauntlet Legends
Hydro Thunder
Iggy's Reckin' Balls
Kirby 64: The Crystal Shards
The Legend of Zelda: Majora's Mask
The Legend of Zelda: Ocarina of Time
Mario Golf
Mario Kart 64
Mario Party 3
Mario Tennis
Midway's Greatest Arcade Hits
Milo's Astro Lanes
Mortal Kombat 4
Namco Museum 64
The New Tetris
Paper Mario
Pilotwings 64
Pokémon Snap
Rampage 2: Universal Tour
Ready 2 Rumble Boxing
Rush 2: Extreme Racing USA
San Francisco Rush: Extreme Racing
Star Fox 64
Star Wars: Rogue Squadron
Super Mario 64
Super Smash Bros.
Turok 2: Seeds of Evil
Virtual Chess 64
Virtual Pool 64
Wave Race 64
Yoshi's Story
GameCube
There were 43 Nintendo GameCube titles available to play on LodgeNet hotel televisions.
1080° Avalanche
Animal Crossing
Backyard Baseball 2007
Battalion Wars
Chibi-Robo!
Custom Robo
Eternal Darkness: Sanity's Requiem
Final Fantasy Crystal Chronicles
Fire Emblem: Path of Radiance
Geist
Kirby Air Ride
The Legend of Zelda: Collector's Edition
The Legend of Zelda: Four Swords Adventures
The Legend of Zelda: Ocarina of Time Master Quest
The Legend of Zelda: Twilight Princess
The Legend of Zelda: The Wind Waker
Luigi's Mansion
Mario Golf: Toadstool Tour
Mario Kart: Double Dash!!
Mario Party 4
Mario Party 5
Mario Party 6
Mario Party 7
Mario Power Tennis
Metroid Prime
Metroid Prime 2: Echoes
Paper Mario: The Thousand-Year Door
Pikmin
Pikmin 2
Pokémon Channel
Pokémon Colosseum
Pokémon XD: Gale of Darkness
Star Fox: Assault
Star Wars Rogue Squadron II: Rogue Leader
Star Wars Rogue Squadron III: Rebel Strike
Super Mario Strikers
Super Mario Sunshine
TMNT
Tomb Raider: Legend
The Urbz: Sims in the City
Wario World
WarioWare, Inc.: Mega Party Games!
Wave Race: Blue Storm
Game Boy and Game Boy Color
There were 33 Game Boy/Game Boy Color titles available to play on airlines featuring Nintendo Gateway System.
Baseball
Dr. Mario
F1 Race
Game & Watch Gallery
Game & Watch Gallery 2
Game & Watch Gallery 3
Golf
Kirby's Dream Land 2
Kirby's Pinball Land
Kirby's Star Stacker
Mario Golf
Mario Tennis
Metroid II: Return of Samus
Picross 2
Pokémon Gold Version
Pokémon Silver Version
Pokémon Pinball
Pokémon Puzzle Challenge
Pokémon Red Version
Pokémon Blue Version
Pokémon Trading Card Game
Pokémon Yellow Version
Super Mario Bros. Deluxe
Super Mario Land
Super Mario Land 2
Tennis
The Legend of Zelda: Link's Awakening
The Legend of Zelda: Oracle of Ages
The Legend of Zelda: Oracle of Seasons
Wario Land: Super Mario Land 3
Wario Land II
Wario Land 3
Yakuman
Game Boy Advance
There were 13 Game Boy Advance titles available to play on airlines featuring Nintendo Gateway System.
Advance Wars 2: Black Hole Rising
Dr. Mario & Puzzle League
Fire Emblem: The Blazing Blade
Game & Watch Gallery 4
Kirby: Nightmare in Dream Land
Kirby & the Amazing Mirror
Mario Kart: Super Circuit
Mario Pinball Land
Pokémon Pinball: Ruby & Sapphire
Super Mario Advance 4: Super Mario Bros. 3
Super Mario World: Super Mario Advance 2
The Legend of Zelda: A Link to the Past
Wario Land 4
See also
Interactive television
Smart TV
Sonifi Solutions
Notes
References
External links
1993 in video gaming
Audiovisual introductions in 1993
Television technology
Nintendo hardware | Nintendo Gateway System | [
"Technology"
] | 2,062 | [
"Information and communications technology",
"Television technology"
] |
60,844,925 | https://en.wikipedia.org/wiki/Prasiola%20crispa | Prasiola crispa is a small terrestrial green alga. It has been recorded world-wide mostly from cold-temperate to polar regions.
Taxonomy
The species, first described as Ulva crispa Lightfoot, is the type of the genus Prasiola.
A lectotype was nominated for the species, the type location of which was provided in accompanying notation as walls that faced north and were favoured as urinals.
The specific epithet is said to translate as "crisped", a reference to the irregular convolutions of the species.
Description
This is a small green alga growing to about 6 cm long. The frond is round in shape, flattened. Generally one cell thick, the cells are arranged in rows or in groups of four.
It seems to be an important food source for Antarctic collembolans.
The species has been used a model for the study of the effects of high intensities of UV radiation on photosynthesis.
Reproduction
Reproduction is by akinetes and aplanospores.
Distribution
Recorded world-wide mostly from cold-temperate to polar regions, e.g. from Iceland, the British Isles including the Isle of Man, New Zealand, Japan and the Pacific shores of North America. In Antarctica, the species lives near penguin colonies.
Conservation status
In Iceland, it is red listed as a vulnerable species (VU).
References
Prasiolales
Seaweeds
Species described in 1777
Lichen photobiont | Prasiola crispa | [
"Biology"
] | 297 | [
"Seaweeds",
"Algae"
] |
60,847,281 | https://en.wikipedia.org/wiki/Jarman%E2%80%93Bell%20principle | The Jarman–Bell principle is a concept in ecology that the food quality of a herbivore's intake decreases as the size of the herbivore increases, but the amount of such food increases to counteract the low quality foods. It operates by observing the allometric (non- linear scaling) properties of herbivores. The principle was coined by P.J Jarman (1968.) and R.H.V Bell (1971).
Large herbivores can subsist on low quality food. Their gut size is larger than smaller herbivores. The increased size allows for better digestive efficiency, and thus allow viable consumption of low quality food. Small herbivores require more energy per unit of body mass compared to large herbivores. A smaller size, thus smaller gut size and lower efficiency, imply that these animals need to select high quality food to function. Their small gut limits the amount of space for food, so they eat low quantities of high quality diet. Some animals practice coprophagy, where they ingest fecal matter to recycle untapped/undigested nutrients.
However, the Jarman–Bell principle is not without exception. Small herbivorous members of mammals, birds and reptiles were observed to be inconsistent with the trend of small body mass being linked with high-quality food. There have also been disputes over the mechanism behind the Jarman–Bell principle; that larger body sizes does not increase digestive efficiency.
The implications of larger herbivores ably subsisting on poor quality food compared to smaller herbivores mean that the Jarman–Bell principle may contribute evidence for Cope's rule. Furthermore, the Jarman–Bell principle is also important by providing evidence for the ecological framework of "resource partitioning, competition, habitat use and species packing in environments" and has been applied in several studies.
Links with allometry
Allometry refers to the non-linear scaling factor of one variable with respect to another. The relationship between such variables is expressed as a power law, where the exponent is a value not equal to 1 (thereby implying a non-linear relationship).
Allometric relationships can be mathematically expressed as follow:
(BM = body mass)
Kleiber's law
Kleiber's law describes how larger animals use less energy relative to small animals. Max Kleiber developed a formula that estimates this phenomenon (the exact values are not always consistent).
Where MR = metabolic rate (kcal/day), W = weight/body mass (Kg)
Gut capacity scales linearly with body size (gut capacity = BM1.0) but maintenance metabolism (energy required to maintain homeostasis) scales fractionally ( = BM0.75). Both of these factors are linked through the MR/GC (metabolic requirement to gut capacity ratio). If body mass increases, then the observed ratio demonstrates how large bodies display a lower MR/GC ratio relative to a small body. That is, smaller herbivores require more metabolic energy per unit of body mass than a large one.
Retention time
The allometric scaling of retention time (the time that food remains inside the digestive system) with respect to body mass:
Where Tr = retention time (hours), D = digestibility of the food, W = weight/body mass (Kg).
This formula was refined from a previous iteration because the previous formula took into account the entire gut, rather than focusing on the fermentation site where cellulose (the fibrous substance) is broken down.
Explanation
Food intake
The energy gained food depends on the rate of digestion, retention time and the digestible content of the food.
As herbivores, food intake is achieved through three main steps: ingestion, digestion, and absorption.
Plant- based food is hard to digest and is done so with the help of symbiotic microbes in the gut of the herbivore. When food is passed through the digestive system (including multiple stomach chambers), it breaks down further through symbiotic microbes at fermentation site(s).
There exists different types of stomach plans:
Ruminants: 4 chambered stomach animals with fermentation occurring in the rumen (first stomach).
Pseudoruminants: ruminants but with 3 chambered stomach
Monogastric: one stomach, but fermentation can occur in multiple places depending on the animal. Places include the foregut, colon, caecum and hindgut.
In order, the stomach plans represent the general level of efficiency when digesting plant-based food; ruminants are better compared to pseudoruminants and monogastrics. The development of the rumen not only allows a site for fermentation but also decrease the food digestion (increase retention time). However, a body mass ranging from 600 to 1200 kg is enough to cause sufficient digestion regardless of stomach plan.
Link to the Jarman–Bell principle
The Jarman–Bell Principle implies that the food quality a herbivore consumes is inversely proportional to the size of the herbivore, but the quantity of such food is proportional. The principle relies on the allometric (non-linear) scaling of size and energy requirement.
The metabolic rate per unit of body mass of large animals is slow enough to subside on a consistent flow of low-quality food. However, in small animals, the rate is higher and they cannot draw sufficient energy from low-quality food to live on.
The length of the digestive tract scales proportionally to the size of the animal. A longer digestive tract allows for more retention time and hence increases the efficiency of digestion and absorption.
Larger body mass
Poorer quality food selects animals to grow larger in size, and hence develop an increased digestive efficiency compared to smaller animals. Larger sized animals have a larger/longer digestive tract, allowing for more quantities of low quality food to be processed (retention time). Although herbivores can consume high quality food, the relative abundance of low quality food and other ecological factors such as resource competition and predator presence influence foraging behavior of the animal to primarily consume low quality food. Other factors include the size of the mouth constraining the selective ability of foraging, and the absolute energy large animals require compared to small (though smaller animals require higher energy per unit body mass).
Smaller body mass
Smaller animals have a limited digestive tract relative to larger animals. As such, they have a shorter retention time of food and cannot digest and absorb food to the same degree as larger animals. To counteract this disadvantage, high-quality food is selected, with quantity being limited by the animals gut size. Another method to counteract this is to practice coprophagy, where re-ingestion of fecal matter recycles untapped/undigested nutrients.
However, there are also reports of larger animals, including primates and horses (under dietary restrictions), practicing coprophagy.
Through the extra flexibility of subsisting on low-quality food, the Jarman–Bell Principle suggests an evolutionary advantage of larger animals and hence provides evidence for Cope's rule.
Exceptions
The Jarman–Bell Principle has some notable exceptions. Small herbivorous members of class Mammalia, Aves and Reptilia were observed to be inconsistent with the trend of small body mass being linked with high quality food. This discrepancy could be due to ecological factors which apply pressure and encourage an adaptive approach to the given environment, rather than taking on an optimal form of digestive physiology.
Small rodents subjected to low quality diet were observed to increase food intake and increase the size of their cecum and intestine, counteracting their low quality diet by allowing viable consumption of such food and hence refuting the link between diet quality and body size.
Refuting the mechanism of the Jarman–Bell principle
Although the pattern of low food quality and body size appears consistent across multiple species, the explanation behind the principle (bigger size allowed better digestion via more retention time) has been disputed.
M. Clauss et al. argues that retention time is not proportional to body mass above 500 grams. That is, smaller species (that are above 500 grams but not too large) have been observed to rival larger species in their mean retention time.
Retention time being proportional to food intake was only observed in non-ruminant animals, not ruminants. Clauss et al. suggests that this is due to the diverse adaptations that support the rumen such that the digestive efficiency of ruminants remain consistent and independent of body size and food intake.
Applications and examples
In addition to providing evidence for ecological frameworks such as "resource partitioning, competition, habitat use and species packing in environment" and Cope's rule, the Jarman–Bell Principle has been applied to model primate behaviours and explain sexual segregation in ungulates.
Sexual segregation in polygynous ungulates
Sexual segregation in Soay sheep (Ovis aries) has been observed. Soay sheep are polygynous in nature; males have multiple partners (opposed to polygynandry). Two main hypotheses have been proposed to explain the observed phenomena.
Sexual dimorphism-body size hypothesis
Male soay sheep are morphologically larger than females. Larger overall size implies larger gut size, and hence digestive efficiency. As males are larger they can subsist on lower quality food. This leads to resource partitioning of males and females and thus sexual segregation on an intraspecies level.
Activity budget hypothesis
The time taken to process food depends on the food quality; poorer/high fibre food requires more time to process and ruminate. This extra time influences behaviour and, over a group of ungulates, lead to segregation via food quality. Since males are larger and can handle low quality food, their feeding and ruminating activity will differ from females.
The digestive efficiency between both sexes of Soay sheep
Pérez-Barbería F. J., et al. (2008) tested the proposed hypothesis by feeding Soay sheep grass hay and observing the digestive efficiency between both sexes via their faecal output. Given that the supplied food is the same, more faecal matter implies less digestion and thus lower digestive effectiveness. Male Soay sheep produced less faecal matter than females. Although this result is consistent with the Jarman–Bell principle in that it observes the relationship between size and food quality, it does not adequately explain the proposed hypotheses.
For hypothesis (1), the sheep were kept in an environment where the food abundance and quality were controlled. There was no need for resources to be partitioned and segregation to occur.
For hypothesis (2), there are many external factors which may influence behavioural changes in males, enough to induce sexual segregation, that are not explored in Pérez-Barbería F. J, et al. experiment. In the experiment, the sheep were kept in a controlled environment with a controlled diet (monitoring for digestive efficiency only). Males consume more food than females, thereby having a greater allowance of energy to expend. Activities such as predator lookout, migration or simply standing all use energy, and since males have more energy, there could be enough leeway to induce sexual segregation. However, the cost:benefit ratio of segregating from a group remains equivocal and hard to test.
Size induced sexual segregation threshold
By observing effective food digestibility in Soay sheep, the Jarman–Bell principle seems to apply at an intraspecific level. The threshold at which this occurs was tested at 30%, but other studies (Ruckstuhl and Neuhaus 2002) have shown the threshold to be close to 20%
Modelling primate behavior
Primates are very diverse in their dietary range, general morphological and physiological adaptations. The Jarman–Bell principle was used to help organise these variables. It expects a negative trend between body size and food quality. This trend is supported by observed primate adaptations and how they help them survive in their environment. It can also be used to hypothesis the general diet of newly discovered/mysterious primates that have not been researched by taking into account the animal's body size. For example, information about pygmy chimpanzees was scarce around 1980s. However, it was expected to have a fruity diet.
Steven J. C. Gaulin examined 102 primate species (from various scientific literature) for links between size and diet, and hence the Jarman–Bell principle. Omnivorous primates seemed inconsistent with the trend, likely due to the diversity of their diet.
Carnivorous diets
The aye-aye is a large primate for its nearly exclusive insectivorous diet. This seems inconsistent with the Jarman–Bell principle. However, specialised adaptations, such as large ears and elongated fingers for echolocating larvae, allow the aye-aye to subside on such diet. This supports the idea that the Jarman- Bell Principle is not universal, and that depending on the circumstances (in this case, specialised adaptations), the expected trend is not followed.
Herbivorous diets
Colobines which feed heavily on low- quality food display ruminant like qualities such as digestion via symbiotic microbes in a separate forestomach.
Weasel sportive lemurs are extremely small folivores. They practice coprophagy to maximise nutrient extraction.
The Western gorilla is large and highly herbivorous; its diet contains 90% herbivorous food.
Omnivorous diets
Omnivorous cercopithecoids such as baboons and the patas monkey display the second largest average body mass.
Humans feature such a diverse range of diet that they do not rely on one particular food group.
Both of the above omnivores and the majority of primate omnivores live in open ranges, particularly ecotonal regions (where two biomes meet). In these environments, food abundance is comparatively lower than forest biomes. The diet would shift to a mixture of low amounts of high-quality food, and high amounts of low-quality food to maximise forage and energy.
The universality of the Jarman–Bell principle
Deviations from the expected trend question the universality of the principle. Steven J. C. Gaulin notes that, when the principle is applied to offer any type of explanation, it is subjected to numerous other phenomena that occur at the same time. For example, the habitat range constrains the size of an organism; large primates are too heavy to live on tree tops. Or perhaps the use of adaptations or even tools were enough to allow viable consumption of food quality that would not otherwise be sufficient.
Gigantism in dinosaurs
Extinct dinosaurs, particularly the large sauropods, can be imagined primarily through two methods. Method one involves fossil records; bones and dentition. Method two involves drawing ideas from extant animals and how their body mass is linked with their diet.
Comparing digestion in extant, herbivorous reptiles and mammals and relating this to Sauropod gigantism
Reptiles generally have a shorter retention time than mammals. However, this loss of digestive efficiency is offset by their ability to process food into smaller particles for digestion. Smaller particles are easier to digest and ferment.
As sauropods are reptiles, it would be expected that they have a similar retention time to extant reptiles. However, the lack of particle reduction mechanisms (e.g. gastric mills, chewing teeth) challenges this expectation. Marcus Clauss et al. hypothesised that sauropods have a very enlarged gut capacity to account for this. Retention time is inversely proportional to intake amount. Therefore, an enlarged gut cavity allows increased intake, and thus shorter retention time similar to other herbivorous reptiles.
Nutrient constraints
D. M. Wilkinson and G. D. Ruxton considered the available nutrients as a driving factor for sauropod gigantism. Sauropods appeared during the late triassic period and became extinct at the end of the cretaceous period. During this time period, herbivorous plant matter such as conifers, ginkgos, cycads, ferns and horsetails may have been the dietary choice of sauropods. These plants have a high carbon/nitrogen content. Large amounts of these plant matter would be consumed to meet the bodily nitrogen requirement. Hence, more carbon content is consumed than required.
Clauss Hummel et al. (2005), cited in D. M. Wilkinson and G. D. Ruxton's paper, argues that larger sizes does not necessarily improve digestive efficiency. Rather, it allows nutrient prioritisation. For example, if there exists a diet with high carbon but low nitrogen content, then meeting the nitrogen dietary requirement suggests consuming a high level of carbon diet. Since gut volume scales linearly with body mass, larger animals have more capacity to digests food.
References
Ecological theories
Biological rules
Animal size | Jarman–Bell principle | [
"Biology"
] | 3,470 | [
"Biological rules",
"Animal size",
"Organism size",
"nan"
] |
60,847,424 | https://en.wikipedia.org/wiki/Qianli%20chuan | Qianli chuan () were paddle wheel boats used in medieval China. The boats were driven by human pedaling and were able to cruise hundreds of kilometers per day with no wind blowing.
History
Qianli chuan were invented in the late 5th century AD during the Southern Qi dynasty, and the invention is attributed to the ancient Chinese astronomer and mathematician Zu Chongzhi. References made to the boat were made recalling various tests on the Xinting River, south of modern Nanjing. The boat was proven to be able to cruise several hundred kilometers in a single day without any wind blowing. Late-8th-century AD records have descriptions of the qanli chuan as a type of naval boat that had two wheels found on its sides that was propelled by treadmills.
See also
Naval history of China
References
Chinese inventions
Human-powered watercraft
Marine propulsion
Naval ships of China
Southern Qi | Qianli chuan | [
"Engineering"
] | 179 | [
"Marine propulsion",
"Marine engineering"
] |
60,848,020 | https://en.wikipedia.org/wiki/Tutte%E2%80%93Grothendieck%20invariant | In mathematics, a Tutte–Grothendieck (TG) invariant is a type of graph invariant that satisfies a generalized deletion–contraction formula. Any evaluation of the Tutte polynomial would be an example of a TG invariant.
Definition
A graph function f is TG-invariant if:
Above G / e denotes edge contraction whereas G \ e denotes deletion. The numbers c, x, y, a, b are parameters.
Generalization to matroids
The matroid function f is TG if:
It can be shown that f is given by:
where E is the edge set of M; r is the rank function; and
is the generalization of the Tutte polynomial to matroids.
Grothendieck group
The invariant is named after Alexander Grothendieck because of a similar construction of the Grothendieck group used in the Riemann–Roch theorem. For more details see:
References
Graph invariants | Tutte–Grothendieck invariant | [
"Mathematics"
] | 200 | [
"Graph invariants",
"Mathematical relations",
"Graph theory"
] |
60,848,041 | https://en.wikipedia.org/wiki/Thomas%20J.%20Laffey | Thomas J. Laffey (born December 1943) is an Irish mathematician known for his contributions to group theory and matrix theory. His entire career has been spent at University College Dublin (UCD), where he served two terms as head of the school of mathematics. While he formally retired in 2009, he remains active in research and publishing. The journal Linear Algebra and Its Applications had a special issue (April 2009) to mark his 65th birthday. He received the Hans Schneider Prize in 2013. In May 2019 at UCD, the International Conference on Linear Algebra and Matrix Theory held a celebration to honor Professor Laffey on his 75th birthday.
Education and career
Tom Laffey was born in Cross, County Mayo. His parents were farmers, and the family had no tradition of education. His own early schooling was entirely through the Irish language, and in mathematics and physics he was more or less self-taught. The technical books he had to study were in English, which at first he found challenging. Nobody at his school had attempted honours Leaving Cert maths before. However, he got one of the highest marks in the country in the 1961 Leaving Certificate mathematics examination, thereby earning a state scholarship to university.
He attended University College Galway, earning bachelor's (1964) and master's (1965) degrees in mathematical science and also winning a National University of Ireland Traveling Studentship Prize. In 1968 he was awarded the D.Phil. by the University of Sussex for a thesis on "Structure Theorems for Linear Groups" done under advisor Walter Ledermann.
He immediately joined the staff at University College Dublin, from which he officially retired in 2009, but he has continued to publish regularly. His research has focussed on group theory, and later linear algebra too, and he has supervised five Ph.D. students. He has also played a significant role in the establishment of the Irish Mathematical Olympiad, and had frequently served the BT Young Scientists Exhibition as a judge and reviewer.
Early in his career, he developed a strong interest in matrix theory, due to the influence of Olga Taussky-Todd, with whom he often corresponded. This was cemented by a 1972–3 sabbatical spent at Northern Illinois University.
He received the Hans Schneider Prize in 2013 in recognition of his constructive solution to the NIEP (Non-negative inverse eigenvalue problem) for non-zero spectra.
Selected publications
2018 "The Diagonalizable Nonnegative Inverse Eigenvalue Problem" (with Cronin, A.). Special Matrices, 6 (1) 273–281.
2015 "On a conjecture of Deveci and Karaduman". Linear Algebra and its Applications, Vol 471, 15 April 2015, Pages 569–574.
2012 "A constructive version of the Boyle–Handelman theorem on the spectra of nonnegative matrices". Linear Algebra Appl., Volume 436, Issue 6, 15 March 2012, pages 1701–1709.
2006 "Nonnegative realization of spectra having negative real parts" (with H. Šmigoc). Linear Algebra Appl., 416 (1) 148–159.
2004/2005 "Perturbing non-real eigenvalues of nonnegative real matrices". J. Linear Algebra, 12 73–76 (electronic).
1999 "A characterization of trace zero nonnegative 5 × 5 matrices". (with E. Meehan) Linear Algebra Appl., 302–3.
1996 "The real and the symmetric nonnegative inverse eigenvalue problems are different" (with C.R. Johnson, R. Loewy). Proc. Amer. Math. Soc, 124 (12) 3647–3651.
References
External links
Number theorists
Group theorists
Scholars and academics from County Mayo
Academics of University College Dublin
Alumni of the University of Galway
Alumni of the University of Sussex
1943 births
Living people
20th-century Irish mathematicians
21st-century Irish mathematicians | Thomas J. Laffey | [
"Mathematics"
] | 805 | [
"Number theorists",
"Number theory"
] |
60,849,373 | https://en.wikipedia.org/wiki/Major%20irrigation%20project | Major irrigation project is a classification of irrigation projects used in India. A project with a cultivable command area of more than 10,000 hectares is classified as a major irrigation project. Before the Fifth Five-Year Plan, irrigation schemes were classified on the basis of investments needed to implement the scheme. Since the Fifth Five-Year Plan, India has adopted the command area-based system of classification.
References
Irrigation projects
Irrigation in India | Major irrigation project | [
"Engineering"
] | 88 | [
"Irrigation projects"
] |
60,851,083 | https://en.wikipedia.org/wiki/Maria%20Falkenberg | Maria Falkenberg is a professor of medical biochemistry at the Sahlgrenska Academy of the University of Gothenburg, Sweden. She has made important contributions to understanding how the mitochondrial genome is maintained in health and disease.
Career
Falkenberg received her doctorate from the University of Gothenburg in 2000 for her work on the molecular aspects of DNA replication in Herpes Simplex virus type 1 in the Per Elias group in Gothenburg and the Robert Lehman group at Stanford University. She studied the mechanisms of mitochondrial DNA replication during her postdoctoral fellowship from 2001-2003 in the Nils-Göran Larsson laboratory at the Karolinska Institute, where she then established her own group in 2003. She was the first to set up a cell-free system to study human mitochondrial DNA replication. Her research is funded by among others, the European Research Council (ERC), the Swedish Research Council (VR), and the Knut and Alice Wallenberg Foundation (KAW).
Awards
2019 Appointed Wallenberg Scholar by the Knut and Alice Wallenberg Foundation (KAW)
2017 Election to the Royal Society of Arts and Sciences in Gothenburg (KVVS)
2015 Election to the Royal Swedish Academy of Sciences (KVA)
2012 The Edlunska Prize
2009 Sven och Ebba-Christina Hagbergs Prize in Chemistry
2009 The Fernström Prize
2008 Research Fellow of the Royal Swedish Academy of Sciences
2008 Future Research Leader Award, Swedish Foundation for Strategic Research (SSF)
Selected publications
Copy-choice recombination during mitochondrial L-strand synthesis causes DNA deletions.
Persson Ö, Muthukumar Y, Basu S, Jenninger L, Uhler JP, Berglund AK, McFarland R, Taylor RW, Gustafsson CM, Larsson E, Falkenberg M.
Nat Commun. 2019 Feb 15;10(1):759. doi: 10.1038/s41467-019-08673-5.
Nucleotide pools dictate the identity and frequency of ribonucleotide incorporation in mitochondrial DNA.
Berglund AK, Navarrete C, Engqvist MK, Hoberg E, Szilagyi Z, Taylor RW, Gustafsson CM, Falkenberg M, Clausen AR.
PLoS Genet. 2017 Feb 16;13(2):e1006628. doi: 10.1371/journal.pgen.1006628.
Maintenance and Expression of Mammalian Mitochondrial DNA.
Gustafsson CM, Falkenberg M, Larsson NG.
Annu Rev Biochem. 2016 Jun 2;85:133-60. doi: 10.1146/annurev-biochem-060815-014402.
In vitro-reconstituted nucleoids can block mitochondrial DNA replication and transcription
Géraldine Farge, Majda Mehmedovic, Marian Baclayon, Siet MJL van den Wildenberg, Wouter H Roos, Claes M Gustafsson, Gijs JL Wuite, Maria Falkenberg
Cell Rep. 2014 Jul 10;8(1):66-74. doi: 10.1016/j.celrep.2014.05.046.
In vivo occupancy of mitochondrial single-stranded DNA binding protein supports the strand displacement mode of DNA replication.
Miralles Fusté J, Shi Y, Wanrooij S, Zhu X, Jemt E, Persson Ö, Sabouri N, Gustafsson CM, Falkenberg M.
PLoS Genet. 2014 Dec 4;10(12):e1004832. doi: 10.1371/journal.pgen.1004832.
References
External links
Year of birth missing (living people)
Living people
Academic staff of the University of Gothenburg
University of Gothenburg alumni
Swedish women scientists
Swedish biochemists
Women biochemists
21st-century Swedish women scientists | Maria Falkenberg | [
"Chemistry"
] | 805 | [
"Biochemists",
"Women biochemists"
] |
60,851,292 | https://en.wikipedia.org/wiki/Lightweight%20software | In computing, lightweight software also called lightweight program and lightweight application, is a computer program that is designed to have a small memory footprint (RAM usage) and low CPU usage, overall a low usage of system resources . To achieve this, the software should avoid software bloat and code bloat and try to find the best algorithm efficiency.
See also
Software optimization
Application footprint
Light-weight process
Lightweight protocol
Lightweight Procedure Call
Lightweight programming language
Lightweight markup language
Load (computing)
References
Software optimization | Lightweight software | [
"Technology"
] | 100 | [
"Computing stubs",
"Software stubs"
] |
60,852,153 | https://en.wikipedia.org/wiki/De%20novo%20gene%20birth | De novo gene birth is the process by which new genes evolve from non-coding DNA. De novo genes represent a subset of novel genes, and may be protein-coding or instead act as RNA genes. The processes that govern de novo gene birth are not well understood, although several models exist that describe possible mechanisms by which de novo gene birth may occur.
Although de novo gene birth may have occurred at any point in an organism's evolutionary history, ancient de novo gene birth events are difficult to detect. Most studies of de novo genes to date have thus focused on young genes, typically taxonomically restricted genes (TRGs) that are present in a single species or lineage, including so-called orphan genes, defined as genes that lack any identifiable homolog. It is important to note, however, that not all orphan genes arise de novo, and instead may emerge through fairly well characterized mechanisms such as gene duplication (including retroposition) or horizontal gene transfer followed by sequence divergence, or by gene fission/fusion.
Although de novo gene birth was once viewed as a highly unlikely occurrence, several unequivocal examples have now been described, and some researchers speculate that de novo gene birth could play a major role in evolutionary innovation, morphological specification, and adaptation, probably promoted by their low level of pleiotropy.
History
As early as the 1930s, J. B. S. Haldane and others suggested that copies of existing genes may lead to new genes with novel functions. In 1970, Susumu Ohno published the seminal text Evolution by Gene Duplication. For some time subsequently, the consensus view was that virtually all genes were derived from ancestral genes, with François Jacob famously remarking in a 1977 essay that "the probability that a functional protein would appear de novo by random association of amino acids is practically zero."
In the same year, however, Pierre-Paul Grassé coined the term "overprinting" to describe the emergence of genes through the expression of alternative open reading frames (ORFs) that overlap preexisting genes. These new ORFs may be out of frame with or antisense to the preexisting gene. They may also be in frame with the existing ORF, creating a truncated version of the original gene, or represent 3’ extensions of an existing ORF into a nearby ORF. The first two types of overprinting may be thought of as a particular subtype of de novo gene birth; although overlapping with a previously coding region of the genome, the primary amino-acid sequence of the new protein is entirely novel and derived from a frame that did not previously contain a gene. The first examples of this phenomenon in bacteriophages were reported in a series of studies from 1976 to 1978, and since then numerous other examples have been identified in viruses, bacteria, and several eukaryotic species.
The phenomenon of exonization also represents a special case of de novo gene birth, in which, for example, often-repetitive intronic sequences acquire splice sites through mutation, leading to de novo exons. This was first described in 1994 in the context of Alu sequences found in the coding regions of primate mRNAs. Interestingly, such de novo exons are frequently found in minor splice variants, which may allow the evolutionary “testing” of novel sequences while retaining the functionality of the major splice variant(s).
Still, it was thought by some that most or all eukaryotic proteins were constructed from a constrained pool of “starter type” exons. Using the sequence data available at the time, a 1991 review estimated the number of unique, ancestral eukaryotic exons to be < 60,000, while in 1992 a piece was published estimating that the vast majority of proteins belonged to no more than 1,000 families. Around the same time, however, the sequence of chromosome III of the budding yeast Saccharomyces cerevisiae was released, representing the first time an entire chromosome from any eukaryotic organism had been sequenced. Sequencing of the entire yeast nuclear genome was then completed by early 1996 through a massive, collaborative international effort. In his review of the yeast genome project, Bernard Dujon noted that the unexpected abundance of genes lacking any known homologs was perhaps the most striking finding of the entire project.
In 2006 and 2007, a series of studies provided arguably the first documented examples of de novo gene birth that did not involve overprinting. These studies were conducted using the accessory gland transcriptomes of Drosophila yakuba and Drosophila erecta and they identified 20 putative lineage-restricted genes that appeared unlikely to have resulted from gene duplication. Levine and colleagues identified and confirmed five de novo candidate genes specific to Drosophila melanogaster and/or the closely related Drosophila simulans through a rigorous approach that combined bioinformatic and experimental techniques.
Since these initial studies, many groups have identified specific cases of de novo gene birth events in diverse organisms. The first de novo gene identified in yeast, BSC4 gene was identified in S. cerevisiae in 2008. This gene shows evidence of purifying selection, is expressed at both the mRNA and protein levels, and when deleted is synthetically lethal with two other yeast genes, all of which indicate a functional role for the BSC4 gene product. Historically, one argument against the notion of widespread de novo gene birth is the evolved complexity of protein folding. Interestingly, Bsc4 was later shown to adopt a partially folded state that combines properties of native and non-native protein folding. In plants, the first de novo gene to be functionally characterized was QQS, an Arabidopsis thaliana gene identified in 2009 that regulates carbon and nitrogen metabolism. The first functionally characterized de novo gene identified in mice, a noncoding RNA gene, was also described in 2009. In primates, a 2008 informatic analysis estimated that 15/270 primate orphan genes had been formed de novo. A 2009 report identified the first three de novo human genes, one of which is a therapeutic target in chronic lymphocytic leukemia. Since this time, a plethora of genome-level studies have identified large numbers of orphan genes in many organisms, although the extent to which they arose de novo, and the degree to which they can be deemed functional, remain debated.
Identification
Identification of de novo emerging sequences
There are two major approaches to the systematic identification of novel genes: genomic phylostratigraphy and synteny-based methods. Both approaches are widely used, individually or in a complementary fashion.
Genomic phylostratigraphy
Genomic phylostratigraphy involves examining each gene in a focal, or reference, species and inferring the presence or absence of ancestral homologs through the use of the BLAST sequence alignment algorithms or related tools. Each gene in the focal species can be assigned an age (aka “conservation level” or “genomic phylostratum”) that is based on a predetermined phylogeny, with the age corresponding to the most distantly related species in which a homolog is detected. When a gene lacks any detectable homolog outside of its own genome, or close relatives, it is said to be a novel, taxonomically restricted or orphan gene.
Phylostratigraphy is limited by the set of closely related genomes that are available, and results are dependent on BLAST search criteria. In addition, it is often difficult to determine based on lack of observed sequence similarity whether a novel gene has emerged de novo or has diverged from an ancestral gene beyond recognition, for instance following a duplication event. This was pointed out by a study that simulated the evolution of genes of equal age and found that distant orthologs can be undetectable for rapidly evolving genes. On the other hand, when accounting for changes in the rate of evolution in young regions of genes, a phylostratigraphic approach was more accurate at assigning gene ages in simulated data. Subsequent studies using simulated evolution found that phylostratigraphy failed to detect an ortholog in the most distantly related species for 13.9% of D. melanogaster genes and 11.4% of S. cerevisiae genes. However, a reanalysis of studies that used phylostratigraphy in yeast, fruit flies and humans found that even when accounting for such error rates and excluding difficult-to-stratify genes from the analyses, the qualitative conclusions were unaffected. The impact of phylostratigraphic bias on studies examining various features of de novo genes remains debated.
Synteny-based approaches
Synteny-based approaches use order and relative positioning of genes (or other features) to identify the potential ancestors of candidate de novo genes. Syntenic alignments are anchored by conserved “markers.” Genes are the most common marker in defining syntenic blocks, although k-mers and exons are also used. Confirmation that the syntenic region lacks coding potential in outgroup species allows a de novo origin to be asserted with higher confidence. The strongest possible evidence for de novo emergence is the inference of the specific "enabling" mutation(s) that created coding potential, typically through the analysis of smaller sequence regions, termed microsyntenic regions, of closely related species.
One challenge in applying synteny-based methods is that synteny can be difficult to detect across longer timescales. To address this, various optimization techniques have been created, such as using exons clustered irrespective of their specific order to define syntenic blocks or algorithms that use well-conserved genomic regions to expand microsyntenic blocks. There are also difficulties associated with applying synteny-based approaches to genome assemblies that are fragmented or in lineages with high rates of chromosomal rearrangements, as is common in insects. Synteny-based approaches can be applied to genome-wide surveys of de novo genes and represent a promising area of algorithmic development for gene birth dating. Some have used synteny-based approaches in combination with similarity searches in an attempt to develop standardized, stringent pipelines that can be applied to any group of genomes in an attempt to address discrepancies in the various lists of de novo genes that have been generated.
Determination of status
Even when the evolutionary origin of a particular coding sequence has been established, there is still a lack of consensus about what constitutes a genuine de novo gene birth event. One reason for this is a lack of agreement on whether or not the entirety of the sequence must be non-genic in origin. For protein-coding de novo genes, it has been proposed that de novo genes be divided into subtypes based on the proportion of the ORF in question that was derived from a previously noncoding sequence. Furthermore, for de novo gene birth to occur, the sequence in question must be a gene which has led to a questioning of what constitutes a gene, with some models establishing a strict dichotomy between genic and non-genic sequences, and others proposing a more fluid continuum.
All definitions of genes are linked to the notion of function, as it is generally agreed that a genuine gene should encode a functional product, be it RNA or protein. There are, however, different views of what constitutes function, depending whether a given sequence is assessed using genetic, biochemical, or evolutionary approaches. The ambiguity of the concept of ‘function’ is especially problematic for the de novo gene birth field, where the objects of study are often rapidly evolving. To address these challenges, the Pittsburgh Model of Function deconstructs ‘function’ into five meanings to describe the different properties that are acquired by a locus undergoing de novo gene birth: Expression, Capacities, Interactions, Physiological Implications, and Evolutionary Implications.
It is generally accepted that a genuine de novo gene is expressed in at least some context, allowing selection to operate, and many studies use evidence of expression as an inclusion criterion in defining de novo genes. The expression of sequences at the mRNA level may be confirmed individually through techniques such as quantitative PCR, or globally through RNA sequencing (RNA-seq). Similarly, expression at the protein level can be determined with high confidence for individual proteins using techniques such as mass spectrometry or western blotting, while ribosome profiling (Ribo-seq) provides a global survey of translation in a given sample. Ideally, to confirm a gene arose de novo, a lack of expression of the syntenic region of outgroup species would also be demonstrated.
Genetic approaches to detect a specific phenotype or change in fitness upon disruption of a particular sequence, are useful to infer function. Other experimental approaches, including screens for protein-protein and/or genetic interactions, may also be employed to confirm a biological effect for a particular de novo ORF.
Evolutionary approaches may be employed to infer the existence of a molecular function from computationally derived signatures of selection. In the case of TRGs, one common signature of selection is the ratio of nonsynonymous to synonymous substitutions (dN/dS ratio), calculated from different species from the same taxon. Similarly, in the case of species-specific genes, polymorphism data may be used to calculate a pN/pS ratio from different strains or populations of the focal species. Given that young, species-specific de novo genes lack deep conservation by definition, detecting statistically significant deviations from 1 can be difficult without an unrealistically large number of sequenced strains/populations. An example of this can be seen in Mus musculus, where three very young de novo genes lack signatures of selection despite well-demonstrated physiological roles. For this reason, pN/pS approaches are often applied to groups of candidate genes, allowing researchers to infer that at least some of them are evolutionarily conserved, without being able to specify which. Other signatures of selection, such as the degree of nucleotide divergence within syntenic regions, conservation of ORF boundaries, or for protein-coding genes, a coding score based on nucleotide hexamer frequencies, have instead been employed.
Prevalence
Estimates of numbers
Frequency and number estimates of de novo genes in various lineages vary widely and are highly dependent on methodology. Studies may identify de novo genes by phylostratigraphy/BLAST-based methods alone, or may employ a combination of computational techniques, and may or may not assess experimental evidence for expression and/or biological role. Furthermore, genome-scale analyses may consider all or most ORFs in the genome, or may instead limit their analysis to previously annotated genes.
The D. melanogaster lineage is illustrative of these differing approaches. An early survey using a combination of BLAST searches performed on cDNA sequences along with manual searches and synteny information identified 72 new genes specific to D. melanogaster and 59 new genes specific to three of the four species in the D. melanogaster species complex. This report found that only 2/72 (~2.8%) of D. melanogaster-specific new genes and 7/59 (~11.9%) of new genes specific to the species complex were derived de novo, with the remainder arising via duplication/retroposition. Similarly, an analysis of 195 young (<35 million years old) D. melanogaster genes identified from syntenic alignments found that only 16 had arisen de novo. In contrast, an analysis focused on transcriptomic data from the testes of six D. melanogaster strains identified 106 fixed and 142 segregating de novo genes. For many of these, ancestral ORFs were identified but were not expressed. A newer study found that up to 39 % of orphan genes in the Drosophila clade may have emerged de novo, as they overlap with non-coding regions of the genome. Highlighting the differences between inter- and intra-species comparisons, a study in natural Saccharomyces paradoxus populations found that the number of de novo polypeptides identified more than doubled when considering intra-species diversity. In primates, one early study identified 270 orphan genes (unique to humans, chimpanzees, and macaques), of which 15 were thought to have originated de novo. Later reports identified many more de novo genes in humans alone that are supported by transcriptional and proteomic evidence. Studies in other lineages/organisms have also reached different conclusions with respect to the number of de novo genes present in each organism, as well as the specific sets of genes identified. A sample of these large-scale studies is described in the table below.
Generally speaking, it remains debated whether duplication and divergence or de novo gene birth represent the dominant mechanism for the emergence of new genes, in part because de novo genes are likely to both emerge and be lost more frequently than other young genes. In a study on the origin of orphan genes in 3 different eukaryotic lineages, authors found that on average only around 30% of orphan genes can be explained by sequence divergence.
Dynamics
It is important to distinguish between the frequency of de novo gene birth and the number of de novo genes in a given lineage. If de novo gene birth is frequent, it might be expected that genomes would tend to grow in their gene content over time; however, the gene content of genomes is usually relatively stable. This implies that a frequent gene death process must balance de novo gene birth, and indeed, de novo genes are distinguished by their rapid turnover relative to established genes. In support of this notion, recently emerged Drosophila genes are much more likely to be lost, primarily through pseudogenization, with the youngest orphans being lost at the highest rate; this is despite the fact that some Drosophila orphan genes have been shown to rapidly become essential. A similar trend of frequent loss among young gene families was observed in the nematode genus Pristionchus. Similarly, an analysis of five mammalian transcriptomes found that most ORFs in mice were either very old or species specific, implying frequent birth and death of de novo transcripts. A comparable trend could be shown by further analyses of six primate transcriptomes. In wild S. paradoxus populations, de novo ORFs emerge and are lost at similar rates. Nevertheless, there remains a positive correlation between the number of species-specific genes in a genome and the evolutionary distance from its most recent ancestor. A rapid gain and loss of de novo genes was also found on a population level by analyzing nine natural three-spined stickleback populations. In addition to the birth and death of de novo genes at the level of the ORF, mutational and other processes also subject genomes to constant “transcriptional turnover”. One study in murines found that while all regions of the ancestral genome were transcribed at some point in at least one descendant, the portion of the genome under active transcription in a given strain or subspecies is subject to rapid change. The transcriptional turnover of noncoding RNA genes is particularly fast compared to coding genes.
Examples de novo genes
Features
General Features
Recently emerged de novo genes differ from established genes in a number of ways. Across a broad range of species, young and/or taxonomically restricted genes have been reported to be shorter in length than established genes, more positively charged, faster evolving, and to be less expressed. Although these trends could be a result of homology detection bias, a reanalysis of several studies that accounted for this bias found that the qualitative conclusions reached were unaffected. Another feature includes the tendency for young genes to have their hydrophobic amino acids more clustered near one another along the primary sequence.
The expression of young genes has also been found to be more tissue- or condition-specific than that of established genes. In particular, relatively high expression of de novo genes was observed in male reproductive tissues in Drosophila, stickleback, mice, and humans, and, in the human brain. In animals with adaptive immune systems, higher expression in the brain and testes may be a function of the immune-privileged nature of these tissues. An analysis in mice found specific expression of intergenic transcripts in the thymus and spleen (in addition to the brain and testes). It has been proposed that in vertebrates de novo transcripts must first be expressed in tissues lacking immune cells before they can be expressed in tissues that have immune surveillance.
Evolutionary rate
For sequence evolution, dN/dS analysis studies often indicate that de novo genes evolve at a higher rate compared to other genes. For expression evolution and structural evolution, quantitative studies across different evolutionary ages or phylostratigraphic branches are very few.
Features that promote de novo gene birth
Its also of interest to compare features of recently emerged de novo genes to the pool of non-genic ORFs from which they emerge. Theoretical modeling has shown that such differences are the product both of selection for features that increase the likelihood of functionalization, and of neutral evolutionary forces that influence allelic turnover. Experiments in S. cerevisiae showed that predicted transmembrane domains were strongly associated with beneficial fitness effects when young ORFs were overexpressed, but not when established (older) ORFs were overexpressed. Experiments in E. coli showed that random peptides tended to have more benign effects when they were enriched for amino acids that were small, and that promoted intrinsic structural disorder.
Lineage-dependent features
Features of de novo genes can depend on the species or lineage being examined. This appears to partly be a result of varying GC content in genomes and that young genes bear more similarity to non-genic sequences from the genome in which they arose than do established genes. Features in the resulting protein, such as the percentage of transmembrane residues and the relative frequency of various predicted secondary structural features show a strong GC dependency in orphan genes, whereas in more ancient genes these features are only weakly influenced by GC content.
The relationship between gene age and the amount of predicted intrinsic structural disorder (ISD) in the encoded proteins has been subject to considerable debate. It has been claimed that ISD is also a lineage-dependent feature, exemplified by the fact that in organisms with relatively high GC content, ranging from D. melanogaster to the parasite Leishmania major, young genes have high ISD, while in a low GC genome such as budding yeast, several studies have shown that young genes have low ISD. However, a study that excluded young genes with dubious evidence for functionality, defined in binary terms as being under selection for gene retention, found that the remaining young yeast genes have high ISD, suggesting that the yeast result may be due to contamination of the set of young genes with ORFs that do not meet this definition, and hence are more likely to have properties that reflect GC content and other non-genic features of the genome. Beyond the very youngest orphans, this study found that ISD tends to decrease with increasing gene age, and that this is primarily due to amino acid composition rather than GC content. Within shorter time scales, using de novo genes that have the most validation suggests that younger genes are more disordered in Lachancea, but less disordered in Saccharomyces. Intrinsic structural disorder and aggregation propensity did not show significant differences with age in some studies of mammals and primates, but did in other studies of mammals. One large study of the entire Pfam protein domain database showed enrichment of younger protein domain for disorder-promoting amino acids across animals, but enrichment on the basis of amino acid availability in plants.
Role of epigenetic modifications
An examination of de novo genes in A. thaliana found that they are both hypermethylated and generally depleted of histone modifications. In agreement with either the proto-gene model or contamination with non-genes, methylation levels of de novo genes were intermediate between established genes and intergenic regions. The methylation patterns of these de novo genes are stably inherited, and methylation levels were highest, and most similar to established genes, in de novo genes with verified protein-coding ability. In the pathogenic fungus Magnaporthe oryzae, less conserved genes tend to have methylation patterns associated with low levels of transcription. A study in yeasts also found that de novo genes are enriched at recombination hotspots, which tend to be nucleosome-free regions.
In Pristionchus pacificus, orphan genes with confirmed expression display chromatin states that differ from those of similarly expressed established genes. Orphan gene start sites have epigenetic signatures that are characteristic of enhancers, in contrast to conserved genes that exhibit classical promoters. Many unexpressed orphan genes are decorated with repressive histone modifications, while a lack of such modifications facilitates transcription of an expressed subset of orphans, supporting the notion that open chromatin promotes the formation of novel genes.
Structural evolution
De novo proteins typically exhibit less well-defined secondary and three-dimensional structures, often lacking rigid folding but having extensive disordered regions. Quantitative analyses are still lacking on the evolution of secondary structural elements and tertiary structures over time. As structure is usually more conserved than sequence, comparing structures between orthologs could provide deeper insides into de novo gene emergence and evolution and help to confirm these genes as true de novo genes. Nevertheless, so far only very few de novo proteins have been structurally and functionally characterized, especially due to problems with protein purification and subsequent stability. Progresses have been made using different purification tags, cell types and chaperones.
The ‘antifreeze glycoprotein’ (AFGP) in Arctic codfishes prevents their blood from freezing in arctic waters. Bsc4, a short non-essential de novo protein in yeast, has been shown to be built mainly by β-sheets and has a hydrophobic core. It is associated to DNA repair under nutrient-deficient conditions. The Drosophila de novo protein Goddard has been characterized for the first time in 2017. Knockdown Drosophila melanogaster male flies were not able to produce sperm. Recently, it could be shown that this lack was due to failure of individualization of elongated spermatids. By using computational phylogenomic and structure predictions, experimental structural analyses, and cell biological assays, it was proposed that half of Goddard's structure is disordered and the other half is composed by alpha-helical amino acids. These analyses also indicated that Goddard's orthologs show similar results. Goddard's structure therefore appears to have been mainly conserved since its emergence.
Mechanisms
Pervasive expression
With the development of technologies such as RNA-seq and Ribo-seq, eukaryotic genomes are now known to be pervasively transcribed and translated. Many ORFs that are either unannotated, or annotated as long non-coding RNAs (lncRNAs), are translated at some level, either in a condition or tissue-specific manner. Though infrequent, these translation events expose non-genic sequence to selection. This pervasive expression forms the basis for several models describing de novo gene birth.
It has been speculated that the epigenetic landscape of de novo genes in the early stages of formation may be particularly variable between and among populations, resulting in variable gene expression thereby allowing young genes to explore the “expression landscape.” The QQS gene in A. thaliana is one example of this phenomenon; its expression is negatively regulated by DNA methylation that, while heritable for several generations, varies widely in its levels both among natural accessions and within wild populations. Epigenetics are also largely responsible for the permissive transcriptional environment in the testes, particularly through the incorporation into nucleosomes of non-canonical histone variants that are replaced by histone-like protamines during spermatogenesis.
Intergenic ORFs as elementary structural modules
Analysis of the fold potential diversity shows that the majority of the amino acid sequences encoded by the intergenic ORFs of S. cerevisiae are predicted to be foldable. More importantly, these amino acid sequences with folding potential can serve as elementary building blocks for de novo genes or integrate into pre-existing genes.
Order of events
For birth of a de novo protein-coding gene to occur, a non-genic sequence must both be transcribed and acquire an ORF before becoming translated. These events could occur in either order, and there is evidence supporting both an “ORF first” and a “transcription first” model. An analysis of de novo genes that are segregating in D. melanogaster found that sequences that are transcribed had similar coding potential to the orthologous sequences from lines lacking evidence of transcription. This finding supports the notion that many ORFs can exist prior to being transcribed. The antifreeze glycoprotein gene AFGP, which emerged de novo in Arctic codfishes, provides a more definitive example in which the de novo emergence of the ORF was shown to precede the promoter region. Furthermore, putatively non-genic ORFs long enough to encode functional peptides are numerous in eukaryotic genomes, and expected to occur at high frequency by chance. Through tracing the evolution history of ORF sequences and transcription activation of human de novo genes, a study showed that some ORFs were ready to confer biological significance upon their birth. At the same time, transcription of eukaryotic genomes is far more extensive than previously thought, and there are documented examples of genomic regions that were transcribed prior to the appearance of an ORF that became a de novo gene. The proportion of de novo genes that are protein-coding is unknown, but the appearance of “transcription first” has led some to posit that protein-coding de novo genes may first exist as RNA gene intermediates. The case of bifunctional RNAs, which are both translated and function as RNA genes, shows that such a mechanism is plausible.
The two events may occur simultaneously when chromosomal rearrangement is the event that precipitates gene birth.
Models
Several theoretical models and possible mechanisms of de novo gene birth have been described. The models are generally not mutually exclusive, and it is possible that multiple mechanisms may give rise to de novo genes. An example is the type III antifreeze protein gene, which originates from an old sialic acid synthase (SAS) gene, in an Antarctic zoarcid fish.
“Out of Testis” hypothesis
An early case study of de novo gene birth, which identified five de novo genes in D. melanogaster, noted preferential expression of these genes in the testes, and several additional de novo genes were identified using transcriptomic data derived from the testes and male accessory glands of D. yakuba and D. erecta. This is in agreement with other studies that showed there is rapid evolution of genes related to reproduction across a range of lineages, suggesting that sexual selection may play a key role in adaptive evolution and de novo gene birth. A subsequent large-scale analysis of six D. melanogaster strains identified 248 testis-expressed de novo genes, of which ~57% were not fixed. A recent study on twelve Drosophila species additionally identified a higher proportion of de novo genes with testis-biased expression compared to annotated proteome. It has been suggested that the large number of de novo genes with male-specific expression identified in Drosophila is likely due to the fact that such genes are preferentially retained relative to other de novo genes, for reasons that are not entirely clear. Interestingly, two putative de novo genes in Drosophila (Goddard and Saturn) were shown to be required for normal male fertility. A genetic screen of over 40 putative de novo genes with testis-enriched expression in Drosophila melanogaster revealed that one of the de novo genes, atlas, was required for proper chromatin condensation during the final stages of spermatogenesis in male. atlas evolved from the fusion of a protein-coding gene that arose at the base of Drosophila genus and a conserved non-coding RNA. Comparative analysis of the transcriptomes of testis and accessory glands, a somatic tissue of males that is important for fertility, of D. melanogaster suggests that de novo genes make greater contribution to the transcriptomic complexity of testis as compared to accessory glands. Single-cell RNA-seq of D. melanogaster testis revealed that the expression pattern of de novo genes was biased toward early spermatogenesis.
In humans, a study that identified 60 human-specific de novo genes found that their average expression, as measured by RNA-seq, was highest in the testes. Another study looking at mammalian-specific genes more generally also found enriched expression in the testes. Transcription in mammalian testes is thought to be particularly promiscuous, due in part to elevated expression of the transcription machinery and an open chromatin environment. Along with the immune-privileged nature of the testes, this promiscuous transcription is thought to create the ideal conditions for the expression of non-genic sequences required for de novo gene birth. Testes-specific expression seems to be a general feature of all novel genes, as an analysis of Drosophila and vertebrate species found that young genes showed testes-biased expression regardless of their mechanism of origination.
Preadaptation model
The preadaptation model of de novo gene birth uses mathematical modeling to show that when sequences that are normally hidden are exposed to weak or shielded selection, the resulting pool of “cryptic” sequences (i.e. proto-genes) can be purged of “self-evidently deleterious” variants, such as those prone to lead to protein aggregation, and thus enriched in potential adaptations relative to a completely non-expressed and unpurged set of sequences. This revealing and purging of cryptic deleterious non-genic sequences is a byproduct of pervasive transcription and translation of intergenic sequences, and is expected to facilitate the birth of functional de novo protein-coding genes. This is because by eliminating the most deleterious variants, what is left is, by a process of elimination, more likely to be adaptive than expected from random sequences. Using the evolutionary definition of function (i.e. that a gene is by definition under purifying selection against loss), the preadaptation model assumes that “gene birth is a sudden transition to functionality” that occurs as soon as an ORF acquires a net beneficial effect. In order to avoid being deleterious, newborn genes are expected to display exaggerated versions of genic features associated with the avoidance of harm. This is in contrast to the proto-gene model, which expects newborn genes to have features intermediate between old genes and non-genes.
The mathematics of the preadaptation model assume that the distribution of fitness effects is bimodal, with new sequences of mutations tending to break something or tinker, but rarely in between. Following this logic, populations may either evolve local solutions, in which selection operates on each individual locus and a relatively high error rate is maintained, or a global solution with a low error rate which permits the accumulation of deleterious cryptic sequences. De novo gene birth is thought to be favored in populations that evolve local solutions, as the relatively high error rate will result in a pool of cryptic variation that is “preadapted” through the purging of deleterious sequences. Local solutions are more likely in populations with a high effective population size.
In support of the preadaptation model, an analysis of ISD in mice and yeast found that young genes have higher ISD than old genes, while random non-genic sequences tend to show the lowest levels of ISD. Although the observed trend may have partly resulted from a subset of young genes derived by overprinting, higher ISD in young genes is also seen among overlapping viral gene pairs. With respect to other predicted structural features such as β-strand content and aggregation propensity, the peptides encoded by proto-genes are similar to non-genic sequences and categorically distinct from canonical genes.
Proto-gene model
This proto-gene model agrees with the preadaptation model about the importance of pervasive expression, and refers to the set of pervasively expressed sequences that do not meet all definitions of a gene as “proto-genes”. In contrast to the preadaptation model, the proto-gene model, suggests newborn genes have features intermediate between old genes and non-genes. Specifically this model envisages a more gradual process under selection from non-genic to genic state, rejecting the binary classification of gene and non-gene.
In an extension of the proto-gene model, it has been proposed that as proto-genes become more gene-like, their potential for adaptive change gives way to selected effects; thus, the predicted impact of mutations on fitness is dependent on the evolutionary status of the ORF. This notion is supported by the fact that overexpression of established ORFs in S. cerevisiae tends to be less beneficial (and more harmful) than does overexpression of emerging ORFs.
Several features of ORFs correlate with ORF age as determined by phylostratigraphic analysis, with young ORFs having properties intermediate between old ORFs and non-genes; this has been taken as evidence in favor of the proto-gene model, in which proto-gene state is a continuum . This evidence has been criticized, because the same apparent trends are also expected under a model in which identity as a gene is a binary. Under this model, when each age group contains a different ratio of genes vs. non-genes, Simpson's paradox can generate correlations in the wrong direction.
Grow slow and moult model
The “grow slow and moult” model describes a potential mechanism of de novo gene birth, particular to protein-coding genes. In this scenario, existing protein-coding ORFs expand at their ends, especially their 3’ ends, leading to the creation of novel N- and C-terminal domains. Novel C-terminal domains may first evolve under weak selection via occasional expression through read-through translation, as in the preadaptation model, only later becoming constitutively expressed through a mutation that disrupts the stop codon. Genes experiencing high translational readthrough tend to have intrinsically disordered C-termini. Furthermore, existing genes are often close to repetitive sequences that encode disordered domains. These novel, disordered domains may initially confer some non-specific binding capability that becomes gradually refined by selection. Sequences encoding these novel domains may occasionally separate from their parent ORF, leading or contributing to the creation of a de novo gene. Interestingly, an analysis of 32 insect genomes found that novel domains (i.e. those unique to insects) tend to evolve fairly neutrally, with only a few sites under positive selection, while their host proteins remain under purifying selection, suggesting that new functional domains emerge gradually and somewhat stochastically.
Escape from adaptive conflict
The evolutionary model escape from adaptive conflict (EAC) proposes a possible way for new gene duplication to be fixed: conflict due to contrasting function within a single gene drives the fixation of new duplication.
Pleiotropy-barrier model
The 'pleiotropy-barrier' model suggests that newly evolved genes, including de novo genes and duplication-related genes, could facilitate evolutionary innovation or evolution of specific functions due to their low (or no) pleiotropic effect, when facing new selective force, based on observations from human gene-disease data.
Human health
In addition to its significance for the field of evolutionary biology, de novo gene birth has implications for human health. It has been speculated that novel genes, including de novo genes, may play an outsized role in species-specific traits; however, many species-specific genes lack functional annotation. Nevertheless, there is evidence to suggest that human-specific de novo genes are involved in diseases such as cancer. NYCM, a de novo gene unique to humans and chimpanzees, regulates the pathogenesis of neuroblastomas in mouse models, and the primate-specific PART1, an lncRNA gene, has been identified as both a tumor suppressor and an oncogene in different contexts. Several other human- or primate-specific de novo genes, including PBOV1, GR6, MYEOV, ELFN1-AS1, and CLLU1, are also linked to cancer. Some have even suggested considering tumor-specifically expressed, evolutionary novel genes as their own class of genetic elements, noting that many such genes are under positive selection and may be neofunctionalized in the context of tumors.
The specific expression of many de novo genes in the human brain also raises the intriguing possibility that de novo genes influence human cognitive traits. One such example is FLJ33706, a de novo gene that was identified in GWAS and linkage analyses for nicotine addiction and shows elevated expression in the brains of Alzheimer's patients. Generally speaking, expression of young, primate-specific genes is enriched in the fetal human brain relative to the expression of similarly young genes in the mouse brain. Most of these young genes, several of which originated de novo, are expressed in the neocortex, which is thought to be responsible for many aspects of human-specific cognition. Many of these young genes show signatures of positive selection, and functional annotations indicate that they are involved in diverse molecular processes, but are enriched for transcription factors.
In addition to their roles in cancer processes, de novo originated human genes have been implicated in the maintenance of pluripotency and in immune function. The preferential expression of de novo genes in the testes is also suggestive of a role in reproduction. Given that the function of many de novo human genes remains uncharacterized, it seems likely that an appreciation of their contribution to human health and development will continue to grow.
Genome-scale studies of orphan and de novo genes in various lineages.
Note: For purposes of this table, genes are defined as orphan genes (when species-specific) or TRGs (when limited to a closely related group of species) when the mechanism of origination has not been investigated, and as de novo genes when de novo origination has been inferred, irrespective of method of inference. The designation of de novo genes as “candidates” or “proto-genes” reflects the language used by the authors of the respective studies.
See also
Molecular evolution
Population genetics
Evolvability
Overlapping gene
Orphan gene
References
Genes
Modification of genetic information | De novo gene birth | [
"Biology"
] | 8,808 | [
"Modification of genetic information",
"Molecular genetics"
] |
60,852,572 | https://en.wikipedia.org/wiki/Design%20culture | Design culture is an organizational culture focused on approaches that improve customer experiences through design. In every firm, the design culture is of significance as it allows the company to understand users and their needs. Integration of design culture in any organization aims at creating experiences that add value to their respective users. In general, design culture entails undertaking design as the forefront of every operation in the organization, from strategy formulation to execution. Every organization is responsible for ensuring a healthy design culture through the application of numerous strategies. For instance, an organization should provide a platform that allows every stakeholder to engage in design recesses. Consequently, employees across the board need to incorporate design thinking, which is associated with innovation and critical thinking.
Moreover, design culture has many characteristics that create a conducive integration within the work environment. It offers freedom for design experimentation through course corrections. Therefore, individuals involved in design processes learn from their mistakes and eventually develop innovative solutions. Proactivity in design culture has a positive impact on the organization, specifically on decision-making and problem-solving. Design culture allows designers to engage in constructive tasks. In the process, designers can solve problems in an organization and make crucial decisions towards innovations of the organization. Design culture is concerned with the human side of the respective organization. In the recent past, organizations adopted a data-driven mentality with the success of the organization being measured through the level of efficiency in the operations. In contrast, design culture is interested in the participation of humans in determining the success of the organization through the level of innovation facilitated by their involvement. In return, design culture is concerned with improving an organization's culture into a pleasant and change-driven culture.
Developing a design culture
Creation of a design culture for an organization leads to a better transformation of the organisation. According to a study conducted by Forrester Research Consulting in the year 2016 to investigate whether the design-led cultures gave companies a significant advantage over their contemporaries. The results showed evidence that most of the enterprises that were analyzed during the research had digital experiences that outpaced the competition. The study proved that focusing on design strengthens an organization from the inside as well as from the outside.
In a design-led enterprise, the design permeates the organisation beyond the product teams that are embedded in the culture and in such organizations, there is always an ambition to do better.
These companies typically support a variety of skills from the more oriented designers to the junior designers or the more tactical designers. The teams use collaborative processes and tools to unify the working groups of the organization. An organization driven by design is more proactive rather than reactive, and it tends to confirm the next challenge rather than wait until the challenge presents itself. This is made possible by the values that are built based on, which is done through collaboration, experimentation, empathy as well as user research.
Furthermore, developing a design culture requires a definition of the design and the necessary resources that will facilitate its integration into the organization. This follows an evaluation of the organisation's stakeholders who will be involved in the design process. The evaluation depends on the organisation's culture, which is the defining aspect of an organization's life. Consequently, identifying the designers to be involved in the designing process requires an in-depth understanding of the purpose of the design towards the organisation's culture and innovation as well.
Additionally, building a design culture entails creating an environment that presents a platform that ensures that every individual obtains solutions to some problems present in the organisation. There exist several factors necessary for developing a design culture in any organisation. Cultivating culture is the first approach to developing design culture. This step entails identifying individuals, and their characters, and including them in the design process. The management involved in the design process needs to set the tone for the organisation's culture. Besides, design culture needs to develop an organisation's value in line with the design and ensure that every member of the design team incorporates them in the field of interest.
Developing a design culture requires the incorporation of skilled personnel, alongside innovative and creative individuals as well. However, identifying such individuals is a process in itself. Therefore, the management needs to integrate an effective interview process that will help in the selection of the best skills. Also, it will require motivation for the personnel involved and alignment with the organisation's values. The design culture needs to foster social capital that is responsible for higher information flow, effective collaboration, and collective action of the team. Therefore, building a design culture should facilitate the creation of employee values, recognition of their achievements, enhance communication in the organisation and establish a firm organisation.
Addressing markets and society
Design culture plays a significant role in marketing systems and the surrounding society. It addresses market externalities and internalizes association with the overall performance of the organisations. In addition, design culture allows an organisation to understand users in society and their needs, hence playing a significant role in shaping the product offering. Through design culture, the organisation supports more strategically oriented designers from the society that ensure effective operation in the business. A design-driven organisation tends to be more proactive in the market by defining challenges and strategically working to improve its overall performance. Design culture facilitates the growth of a firm from tiny startups to legacy enterprises. Therefore, in markets and societies, design culture aims at improving an organisation's output to the excellent quality of products, services, and overall societal relationships.
Additionally, design culture needs to consider the aspects of the surrounding society and ensure that the design process is incorporative of the values and culture that is in sync with the surrounding community. The society plays a significant role in the design culture by presenting skilled personnel who can be recruited into the design process. In relation to society, design culture aims at designing a brand for everyone. I. Moreover, the community presents a ready market for the brands designed by the organisation. Consequently, the branding process should consider all the necessary qualities that will maintain the brand in the market. This is enhanced through consideration of the values defining the surrounding society. Moreover, the organisation's culture should be at par with the societal culture to promote collaboration.
Design culture aims at enhancing collaboration in the market with the respective stakeholders. Therefore, introducing design into the market requires intensive research and planning that will facilitate the production of a brand that fits the requirements for all. The design process needs to be aware of the market trends and branded products to solve an existing problem in the market. In addition, the design process should involve designing a brand that provides a solution to various situations in the society. Addressing the market, design culture is concerned about developing a brand that meets the best competitive qualities. Through innovation, the organisation involved in the design process conducts research on different market trends and comes up with refined approaches to be integrated into the design process. Moreover, the organisation needs to maintain its culture that uniquely defines its operations and products in the market. Concerned about the future trend of the design, the management responsible for the design process need to ensure that necessary qualities are met in the design process.
Positioning design professions
As a guiding truth towards the successful firm organisation, design culture takes a psychological approach to different operations of the business. Positioning design professions entails defining numerous approaches necessary for building a healthy design culture. In addition, it focuses on professional strategies that get prospects and customers preferences that enable a business to stand firm in a competitive market. A design-centric organisation is usually biased against leaving anything to chance. A healthy design culture applies not only to the product but also to the organisation itself. Products usually reflect the structure as well as the character of the organisation that is responsible for their production. A well-designed enterprise is capable of producing well-designed products and services. In a healthy design culture, everyone has a feeling of empowerment towards participation in the design process. Employees are usually encouraged to carry out experimentations with the understanding that they will often lead to mistakes, and this should not be a hindrance.
Design culture has innovation as one of its core components. Therefore, the design profession is crucial in the design process as it incorporates necessary branding skills, design skills and knowledge of the design process. The process of cultivating culture requires skills necessary for analysing the surrounding society and determining the required skills for the design process. Setting the tone for an organisation is a professional approach that requires the development of an organisation's values. The design management needs to demonstrate knowledge and an understanding of the conduct of the design team and the level of innovation necessary for the design process.
Furthermore, positioning the design profession requires increased diversity that facilitates innovation. Gender diversity should be maintained in determining the team that will be involved in the design process. In addition, diversity brings heterogenous individuals together who have varying skills, creativity and knowledge that help in branding different products. Branding a product for everyone in society requires extensive research. As a result, the research requires a professional approach that will help in identifying the cultural aspects defining the society. Moreover, identification of the market trends requires in-depth analysis approaches that are in line with design professions. Therefore, the design management team need to ensure an effective and strong position in the design culture that enhances innovation in the design process
Locating design culture
Effective design culture has to be made with intention and put into practice consistently. This requires the definition of approaches necessary for locating design culture. Discovering design culture is facilitated by the need to obtain a solution to a given challenge or the need to champion problem-solving approaches. Locating design culture is done through experimentation, collaboration, user research and empathy. It is a common characteristic for many companies to build a third design culture through trial and error. For example, a company such as Apple has been fine-tuning its design culture for about three decades. Locating design culture require an effective definition of the characteristics of a robust design culture. It requires frequent experimentation that allow individuals to explore as many solutions as possible that result in successful launches. In addition, locating design culture entails implementation of a system that provides answers for questions raised concerning the design culture. Moreover, it involves locating different tools that encourage collaboration allowing a given team to formulate plans, design presentations and work together for successful design culture. Concerning idea generation, it is a norm for every organisation to keep coming up with new ideas now and then, and this allows the organisation to iterate and even receive feedback more efficiently and in a short time
References
Design
Culture | Design culture | [
"Engineering"
] | 2,096 | [
"Design"
] |
60,853,956 | https://en.wikipedia.org/wiki/HDR10%2B | HDR10+ is a high dynamic range (HDR) video technology that adds dynamic metadata to HDR10 source files. The dynamic metadata are used to adjust and optimize each frame of the HDR video to the consumer display's capabilities in a way based on the content creator's intentions.
HDR10+ is an alternative to Dolby Vision, which also uses dynamic metadata. HDR10+ is the default variant of dynamic metadata as part of the HDMI 2.1 standard.
HDR10+ Adaptive is an update designed to optimize HDR10+ content according to the ambient light.
Description
HDR10+, also known as HDR10 Plus, was announced on 20 April 2017, by Samsung and Amazon Video. HDR10+ updates HDR10 by adding dynamic metadata that can be used to more accurately adjust brightness levels up to the full range of PQ code values (10,000 nits maximum brightness) on a scene-by-scene or frame-by-frame basis. The technology is standardized and defined in SMPTE ST 2094-40. HDR10+ is an open standard and is royalty-free; it is supported by a growing list of post-production software and tools. HDR10+ specifications are not publicly available. A certification and logo program for HDR10+ device manufacturers is available with an annual administration fee for certain adopter categories and no per-unit royalty. Authorized test centers conduct certification testing for HDR10+ devices.
On 28 August 2017, Samsung, Panasonic, and 20th Century Fox created the HDR10+ Technologies LLC to promote the HDR10+ standard. HDR10+ video started being offered by Amazon Video on 13 December 2017. On 5 January 2018, Warner Bros. announced their support for the HDR10+ standard. On 6 January 2018, Panasonic announced Ultra HD Blu-ray players with support for HDR10+. On 4 April 2019, Universal Pictures Home Entertainment announced a technology collaboration with Samsung Electronics to release new titles mastered with HDR10+. It is considered to have most of the advantages of Dolby Vision over HDR10, as well as being royalty free.
HDR10+ signals the dynamic range and scene characteristics on a scene-by-scene or even frame-by-frame basis. The display device then uses the dynamic metadata to apply an appropriate tone map through the process of dynamic tone mapping. Dynamic tone mapping differs from static tone mapping by applying a different tone curve from scene-to-scene rather than use a single tone curve for an entire video.
HDR10+ and Dolby Vision do not use the same dynamic metadata.
Technical details
HDR10+ content profile
: SMPTE ST 2084 (PQ)
Chroma subsampling: 4:2:0 (for compressed video sources), 4:2:2 and 4:4:4
Resolution: Agnostic (2K/4K/8K, etc.)
Bit depth: 10-bit or more (up to 16-bit) per color channel
Color primaries: ITU-R BT.2020
Maximum linearized pixel value: 10,000 cd/m2 for each color R/G/B (content)
Metadata (required): Mastering Display Color Volume Metadata
Metadata (optional): MaxCLL, MaxFALL
HDR10+ supports the full range PQ up to 10,000 cd/m2. Being resolution agnostic, metadata needs to be created only once and can be applied to any target resolution.
HDR10+ content can be encoded using video encoding technologies including HEVC (implemented with ) and AV1, VP9 compatibility is achieved via the WebM container.
Workflow and ecosystem
HDR10+ utilizes an HDR10 master file within existing HDR post-production and distribution workflows.
The HDR10+ ecosystem is used within current systems by,
storing HDR10+ metadata in JSON files
embedding HDR10+ metadata into HDR10 encoded content
distribution through digital stream (e.g. streaming with HDR10+ SEI)
displaying HDR10+ content on a capable display (e.g. HDMI interfaces with HDR10+ VSIF) and mobile devices
Metadata generation
For offline and video-on-demand (VOD) (e.g. ultra-high-definition Blu-ray, over-the-top (OTT), multi-channel video programming distributor (MVPD)), HDR10+ metadata may be created during the post-production mastering process or during transcoding/encoding for distribution back-ends by HDR10+ content generation tools in two steps:
Identifying scene cuts, and
Performing an image analysis on each scene or frame to derive statistics
HDR10+ metadata is interchanged through a low complexity JSON-structured text file, which is then parsed and injected into video files.
Live encoding
Live use cases are possible by delivering HDR10+ metadata in every frame. HEVC encoders generate and inject metadata on live content and mobile phones record video and create HDR10+ metadata in real-time during recording. Live encoding is detailed in the Live Encoder Workflow diagram and real time broadcast operations are supported at the point of transmission enabling a metadata-less broadcast operation.
Compatibility
HDR10+ metadata can co-exist with HDR10 static metadata that makes HDR10+ content backward compatible with non-HDR10+ TVs. HDR10+ metadata is ignored by devices that do not support the format and video is played back in HDR10.
Administration
HDR10+ Technologies, LLC administers the license and certification program for products that want to adopt HDR10+. HDR10+ Technologies, LLC provides the technical specifications, test specifications, and certified logo.
Founders
Source:
20th Century Fox (now 20th Century Studios)
Panasonic Corporation
Samsung Electronics
Authorized test centers
Certification of products is done through authorized test centers. The following are a list of HDR10+ authorized test centers:
Allion – Japan
Allion Shenzhen – China
Allion Taipei – Taiwan
BluFocus – United States
Kwangsung – South Korea
SGS-CSTC Standards Technical Services Co. Ltd – China
Shenzhen CESI Information Technology Co., Ltd – China
TIRT – China
TTA – South Korea
Adoption
Adopters
Source:
Google
Amazon
Evertz AV
Panasonic Corporation
Telechips
Amlogic (Shanghai) Co., Ltd.
Extron Electronics
Parade Technologies, Inc.
Teledyne LeCroy
Andy Fiord Production Company
FF Pictures GmbH
Pixelogic Media Partners LLC
TFI Digital Media
Arcelik
Fidelity in Motion
Pixelworks, Inc.
Top Victory Electronics -TPV
Arm Limited
Giant Interactive
Pixtree, Inc.
Toshiba Visual Solutions Corp
Astro Design
Grass Valley K.K.
Turbine Medien GmbH
ATEME SA
Guangdong Oppo Mobile
Qualcomm
20th Century Studios Inc.
Audio Partnership PLC
Interra Systems
Rakuten TV
Unigraf Oy
Beijing Xiaomi Mobile Software
Inventory Films
Realme Chongqing Mobile
US Screen Corp
Blackmagic Design Technology Pte Ltd
Ivi.ru LLC
Realtek Semiconductor Corp.
V-Silicon Inc.
Blackshark Technologies
JVCKENWOOD Corp
Rohde & Schwarz GmbH & Co. KG
Venera Technologies
Broadcom
Loewe Technologies GmbH
Samsung Research America
VeriSilicon, Inc
Capella Systems
Lussier
Shenzhen SDMC Technology Co., Ltd
Vestel Elektronik
Chrontel
MediaArea.net
Shenzhen TCL New Technolog Co., Ltd.
Vicom
Colorfront
Media Tek Inc.
Shenzhen Zidoo Technology Co., Ltd.
VideoQ
Crestron Electronics
MegaChips Technology America
Shout! Factory LLC
Visible Light Digital Inc
Dalet UK Ltd.
Megogo LLC
Sirius Pixels
Vivo Mobile Communications
Deluxe Entertainment Services Group
MTI Film
Socionext, Inc.
Vizio
Digital Vision
Novatek Microelectronics Corp.
Spears & Munsil
Warner Bros. Entertainment
DTS, Inc.
Omnitek
Spin Digital Video Technologies GmbH
Weka Media Publishing
Encoding.com Inc.
OnePlus Technology (Shenzhen) Co., Ltd
Synaptics, Inc.
Xi'an NovaStar Tech Co., Ltd.
Enteractive GmbH
Onkyo Corporation
T1 Technologies
Yamzz IP BV
EON 247, A Public Benefit Corporation
Oppo Digital, Inc.
Tatung Technology Inc.
Shenzhen Amoonsky Technology Co., LTD.
HDR10+ certified products
Certified product categories include:
Ultra-High Definition displays
Ultra-High Definition Blu-ray disc players
Systems-on-chip (SoC)
Set-top boxes
A/V Receivers
Streaming applications
Mobile devices
Inflight Entertainment Systems
References
External links
High dynamic range
Ultra-high-definition television | HDR10+ | [
"Engineering"
] | 1,797 | [
"Electrical engineering",
"High dynamic range"
] |
70,173,377 | https://en.wikipedia.org/wiki/Gymnopilus%20arenophilus | Gymnopilus arenophilus is a species of mushroom-forming fungus in the family Hymenogastraceae. It can be found in Spain and France.
See also
List of Gymnopilus species
References
arenophilus
Fungi of Europe
Fungi described in 2005
Fungus species | Gymnopilus arenophilus | [
"Biology"
] | 60 | [
"Fungi",
"Fungus species"
] |
70,173,434 | https://en.wikipedia.org/wiki/Gymnopilus%20dryophilus | Gymnopilus dryophilus is a species of mushroom in the family Hymenogastraceae. This species is found in North America.
See also
List of Gymnopilus species
References
dryophilus
Fungi of North America
Fungi described in 1943
Fungus species | Gymnopilus dryophilus | [
"Biology"
] | 57 | [
"Fungi",
"Fungus species"
] |
70,173,464 | https://en.wikipedia.org/wiki/Gymnopilus%20pachycystis | Gymnopilus pachycystis is a species of mushroom-forming fungus in the family Hymenogastraceae. It is found in Central America.
See also
List of Gymnopilus species
References
pachycystis
Fungi of Central America
Fungi described in 1989
Taxa named by Rolf Singer
Fungus species | Gymnopilus pachycystis | [
"Biology"
] | 64 | [
"Fungi",
"Fungus species"
] |
70,173,531 | https://en.wikipedia.org/wiki/Gymnopilus%20turficola | Gymnopilus turficola is a species of agaric fungus in the family Hymenogastraceae.
Habitat and distribution
It can be found growing in peat in subarctic tundra in northern Finland and in Finnmark, Norway.
See also
List of Gymnopilus species
References
turficola
Fungi described in 2001
Fungi of Europe
Taxa named by Meinhard Michael Moser
Fungus species | Gymnopilus turficola | [
"Biology"
] | 83 | [
"Fungi",
"Fungus species"
] |
70,173,577 | https://en.wikipedia.org/wiki/Animal%20Locomotion | Animal Locomotion: An Electro-photographic Investigation of Consecutive Phases of Animal Movements is a series of scientific photographs by Eadweard Muybridge made in 1884 and 1885 at the University of Pennsylvania, to study motion in animals (including humans). Published in July 9, 1887, the chronophotographic series comprised 781 collotype plates, each containing up to 36 pictures of the different phases of a specific motion of one subject (over 20,000 images in total).
Following motion studies in California and his lectures with the zoopraxiscope, Muybridge was commissioned by the University of Pennsylvania to oversee the photographic aspects of a scientific study of animal movement. The body of work is celebrated for its contribution to both the art of photography and to science.
History
In 1878, Muybridge published his first series of chronophotographic pictures as 6 cabinet cards entitled The Horse in Motion, from the recordings made as an assignment from industrialist and horse breeder Leland Stanford. The revolutionary images gained worldwide attention and inspired Muybridge to change his career from "photographic view artist" to scientific photographer and lecturer.
In 1879, Muybridge created the zoöpraxiscope (animal action viewer), a projection device that created cyclical animations of animal movement, incorporating technologies from photography, the magic lantern and the zoetrope. The photographer created painted sequences on the glass zoöpraxiscope discs that were based on his motion-study photographs to produce an early form of animation. Muybridge used these to illustrate his lectures that were presented to audiences in the U.S. and Europe, marking his contribution to photography and film in relation to the "experience of time within modernity."
In a 1885 news report, the photographer stated that his interest in animal movement was inspired by observing an eagle flying in the Yosemite Valley in California some years prior. Muybridge described the bird as making "numerous flaps with its wings, but in flying across a valley to another peak it went for a distance of over a mile with but one flap of the wings. I was convinced that individual feather movements upheld and propelled the bird, and I can prove by the negative plates of the eagle whose flight we photographed last Thursday that my conclusion was correct." These earlier photographs in California formed the basis for his later work with the University of Pennsylvania.
Commission
The Animal Locomotion project was a collaborative endeavor between the photographer and the institutional commissioning committee at the University of Pennsylvania. In 1883, Muybridge met with William Pepper and J.B. Lippincott to discuss a plan for a scientific study focused on the analysis of animal and human movement. The university contributed $5,000, seeing the proposed project as important research that would benefit anthropology, physiology, medicine and sports. The commission was appointed in March 1884 and included the University's professors Pepper, Joseph Leidy, George Frederick Barker, Lewis M. Haupt and emeritus Harrison Allen, as well as Thomas Eakins and Edward Hornor Coates of the Pennsylvania Academy of the Fine Arts. The project would eventually last more than three years, and costs rose to almost $30,000, but the University believed the unexpected amount of time and money to be well spent. The huge body of work was thought to be of everlasting importance to science and art and it would take years to examine all the material critically.
From spring 1884 to autumn 1885, Muybridge and his team produced over 100,000 images, mostly at an outdoor studio on the University grounds' northeast corner of 36th and Pine, recording the motions of animals from the veterinary hospital, and from humans: University professors, students, athletes, Blockley Almshouse patients, and local residents. Thomas Eakins worked with him briefly, although the painter preferred working with multiple exposures on a single negative, whereas Muybridge preferred capturing motion through the use of multiple cameras.
Muybridge spent three weeks of August and September 1884, and another three weeks of August 1885, at the Philadelphia Zoo photographing all kinds of animals. Published plates with exotic species include Capybara Walking depicting the world's largest rodent, Ostrich Running (also printed as a cyanotype) and American Bison Cantering,
The pictures of thoroughbred horses were made at the Gentlemen's Driving Park in Philadelphia.
Technology
At the outdoor studio, Muybridge's team used a array of twenty-four 4 by 5 inch cameras, placed 15 centimeters (6 inches) apart at 15 metres (49 feet) from the track. An improved electro-magnetic shutter system with variable rubber bands regulated the exposures. Muybridge had two additional arrays of smaller, portable cameras made; this allowed more flexible placements and quicker operation. The two arrays of 12 cameras each were usually placed at the front and the back of the track, for views of subjects approaching and receding in addition to the lateral views of the 24-camera set. Many of the published series contain 36 pictures, with moving subjects recorded from two or three angles. Muybridge also made studies of foreshortenings with 6 cameras placed at different angles at the same time (comparable to the later bullet time effect).
The trip-wires caused irregular sequences when subjects didn't maintain a constant gait. Muybridge therefore developed a circuit-breaker for making the successive electrical contacts automatically and at equal intervals, long or short, as desired. Each shutter was connected to a chronographic clock that recorded the exposures. Muybridge carried a telegraphic key with him, which was connected to the clockwork and allowed him to fire the whole series of cameras by a touch.
While working in California, Muybridge had used the wet-plate collodion process in making his albumen-print photographs. Once he arrived in Philadelphia, he began to employ a standardized dry-plate process, involving quicker exposure times; these were printed using the collotype photomechanical process.
Content and publication
The published portfolio contained 19 by 24 inch plates in 36 by 36-inch frames, numbered from 1 to 781 in an order mostly based on types of movement (starting with "Walking" followed by "Walking and turning around", "Starting for a run", "Running", et cetera). The plates came in eleven categorized volumes with title pages: Vol. I. & II. Males (nude)., Vol. III. & IV. Females (nude)., Vol. V. Males (pelvis cloth)., Vol. VI. Females (semi-nude and transparent drapery) and Children., Vol. VII. Males and Females (draped) and Miscellaneous Subjects., Vol. VIII. Abnormal Movements. Men and Women (nude and semi-nude)., Vol. IX. Horses., Vol. X. Domestic Animals., and Vol. XI. Wild Animals and Birds. The classification and order of the subjects suggests a hierarchy from nude human males down to chickens, following the Christian concept of the Great chain of being.
Subscribers had the option of selecting 100 plates of their choosing from the portfolio's prospectus and complete catalog for $100. Complete sets were offered for $600, but sold very poorly; reportedly only 37 proper versions were produced.
Contrary to the animal focus suggested by the title of the collection, there were 514 plates of men and women in motion, 27 plates of abnormal male and female movement, 16 of children, 5 of adult male hand movement, and only 221 with animal subjects. Many of the animal plates featured horses, partially a consequence of Muybridge's offering private owners to photograph their horses in exchange for a contribution to the cost of the study. Animals were typically photographed crossing a short distance, human subjects were also portrayed performing activities ranging from typical daily tasks to competitive athletics.
Muybridge classified his adult male human models according to their profession, adult female models ("chosen from all classes of society") to their marital status, age and built. He described himself (model 95) as "an ex-athlete, aged about sixty".
In many cases the human images featured nude or partially-nude men or women, directly confronting a local controversy over the use of nude models in art.
Reception
Muybridge's Animal Locomotion project received attention in the news, who reported on his unusual character and eccentricities as well as the photographic project. The collection's portrayal of nude subjects has been the focus of a directed scholarly study.
Although conceived and initially received as a scientific study, historians note that many of the plates of Animal Locomotion seem to have little to do with science. While most of the male subjects engage in sports or physical labor, most of the movements of female subjects were accessorized with props to create a more imaginative setting, relating to the gendered traditions of 19th century culture. Many of the plates aren't the objective records that were suggested by the use of a chronograph and a background grid; Muybridge was more concerned with esthetics and thus cropped the images, freely omitted elements of a sequence, or combined pictures from different takes.
Legacy
Historians and theoreticians have proposed that Muybridge's work on animal locomotion influenced a number of other artists, photographers and filmmakers, including Marcel Duchamp, Thomas Eakins, Walt Disney, among others.
The composer Philip Glass created a three-part chamber opera titled The Photographer in 1982 that featured a slide show of the motion studies in the second act.
The conceptual artist, Sol LeWitt was inspired by the serial nature of the Animal Locomotion studies, and produced works that directly refers to it.
Poet and legendary singer Jim Morrison wrote about the project in his bundle The Lords and New Creatures (1970): "Muybridge derived his animal subjects from the Philadelphia Zoological Garden, male performers from the University. The women were professional artists’ models, also actresses and dancers, parading nude before the 48 cameras."
In 1992, the Addison Gallery of American Art produced the exhibition, Motion and Document–Sequence and Time: Eadweard Muybridge and Contemporary American Photography, pairing Muybridge's animal motion studies with the work of 42 artists and photographers among them Vito Acconci and Sarah Charlesworth. The show later traveled to the Long Beach Museum of Art.
An animation of one of the Animal Locomotion horse plates was used for a Google doodle on April 9, 2012, to commemorate the 182nd anniversary of Muybridge's birthday.
An animation of Muybridge's pictures of galloping horse Annie G. (plate 626) was featured in Jordan Peele's 2022 science fiction horror film Nope. In the film, Keke Palmer's character Emerald "Em" Haywood claims that she, her brother OJ Haywood (Daniel Kaluuya) and their father are direct descendants of the rider in the photographs. The animation was also featured briefly in Back to the Future: The Game, made by Telltale.
Collections
The University of Pennsylvania houses the Muybridge Collection, which contains 740 of the 781 plates, along with some of his photographic equipment. Images from the series are held in numerous permanent collections including the Royal Academy of Arts, Pennsylvania Academy of Fine Arts, the Metropolitan Museum, the Brooklyn Museum, the Museum of Modern Art and others.
Gallery
References
Further reading
Hendricks, G. Eadweard Muybridge: The Father of the Motion Picture (London: Secker and Warburg, 1975)
Muybridge, Eadweard. Muybridge's Complete Human and Animal Locomotion, Vol. I: All 781 Plates from the 1887 "Animal Locomotion" (1979) Dover Publications
Muybridge, Eadweard. Descriptive Zoopraxography, or the Science of Animal Locomotion Made Popular (1893) Library of Alexandria.
Solnit, Rebecca. Motion Studies: Time, Space and Eadweard Muybridge (London: Bloomsbury, 2004)
External links
Animal locomotion : an electro-photographic investigation of consecutive phases of animal movements Prospectus and Catalog of Plates
Animals in motion: an electro-photographic investigation of consecutive phases of animal progressive movements, 1899 Digital copy by Mart museum, Italy
Eadweard Muybridge Collection, at the University of Pennsylvania
1887 films
1887 works
1887 in film
1880s photographs
1887 short films
History of photography
Photographic collections
1880s in American cinema
Animal locomotion
Stop motion
1880s in animation
Films directed by Eadweard Muybridge
Surviving American silent films | Animal Locomotion | [
"Physics",
"Biology"
] | 2,562 | [
"Animal locomotion",
"Physical phenomena",
"Animals",
"Behavior",
"Motion (physics)",
"Ethology"
] |
70,174,499 | https://en.wikipedia.org/wiki/N-Acetyldopamine | N-Acetyldopamine is the organic compound with the formula CH3C(O)NHCH2CH2C6H3(OH)2. It is the N-acetylated derivative of dopamine. This compound is a reactive intermediate in sclerotization, the process by which insect cuticles are formed by hardening molecular precursors. The catechol substituent is susceptible to redox and crosslinking.
References
Dopamine
Phenethylamine alkaloids | N-Acetyldopamine | [
"Chemistry"
] | 108 | [
"Alkaloids by chemical classification",
"Phenethylamine alkaloids"
] |
70,175,623 | https://en.wikipedia.org/wiki/K-stability%20of%20Fano%20varieties | In mathematics, and in particular algebraic geometry, K-stability is an algebro-geometric stability condition for projective algebraic varieties and complex manifolds. K-stability is of particular importance for the case of Fano varieties, where it is the correct stability condition to allow the formation of moduli spaces, and where it precisely characterises the existence of Kähler–Einstein metrics.
The first attempt to define K-stability for Fano manifolds was made by Gang Tian in 1997, in response to a conjecture of Shing-Tung Yau from 1993 that there should exist a stability condition which characterises the existence of a Kähler–Einstein metric on a Fano manifold. It was defined in reference to the K-energy functional previously introduced by Toshiki Mabuchi. Tian's definition of K-stability was later replaced
by a purely algebro-geometric refinement that was first formulated by Simon Donaldson in 2001.
K-stability has become an important notion in the study and classification of Fano varieties. In 2012 Xiuxiong Chen, Donaldson, and Song Sun proved that a smooth Fano manifold is K-polystable if and only if it admits a Kähler–Einstein metric. (Tian then announced a nearly identical proof, under circumstances that resulted in a bitter priority dispute.) This theorem was later generalised to singular K-polystable Fano varieties due to the work of Berman–Boucksom–Jonsson and others. K-stability is important in constructing moduli spaces of Fano varieties, where observations going back to the original development of geometric invariant theory show that it is necessary to restrict to a class of stable objects to form good moduli. It is now known through the work of Chenyang Xu and others that there exists a projective coarse moduli space of K-polystable Fano varieties of finite type. This work relies on Caucher Birkar's proof of boundedness of Fano varieties, for which he was awarded the 2018 Fields medal. Due to the reformulations of the K-stability condition by Fujita–Li and Odaka, the K-stability of Fano varieties may be explicitly computed in practice. Which Fano varieties are K-stable is well understood in dimension one, two, and three.
Definition and characterisations
The notion of K-stability for Fano manifolds was originally specified using differential geometry by Tian, who extended the purely analytical notion of the Futaki invariant of a vector field to the case of certain normal varieties with orbifold singularities. This was later reformulated in a purely algebro-geometric form by Donaldson, but this general definition lost a direct link to the geometry of Fano varieties, instead making sense for the broader class of all projective varieties. Work of Tian shows that the Donaldson–Futaki invariant specifying the weight of the -action on the central fibre of a test configuration can be computed in terms of certain intersection numbers (corresponding to the weight of an action on the so-called CM line bundle). In the Fano case these intersection numbers, which involve the anticanonical divisor of the variety and its test configuration, can be given powerful alternative characterisations in terms of the algebraic and birational geometry of the Fano variety.
Thus in the case of Fano varieties, there are many different but equivalent characterisations of K-stability, and some of these characterisations lend themselves to explicit calculation or easier proofs of results.
In this section all definitions are stated in the generality of a -Fano variety, which is a Fano variety with ample -Cartier anticanonical divisor and at worst Kawamata log terminal (klt) singularities. The definitions of K-stability can be made for any -Gorenstein Fano variety (that is, any Fano variety where the anticanonical divisor is -Cartier), however it was proven by Odaka that every K-semistable Fano variety has at worst klt singularities, so for the purpose of studying K-stability it suffices to assume at worst klt singularities. Every definition can be extended in a straightforward way to -log Fano pairs, a pair of a klt variety X and klt divisor such that is ample and -Cartier.
Traditional definition
The definition of K-stability for a Fano manifold, or more generally a -Fano variety, can be given in many forms. The general definition of K-stability in terms of test configurations (see K-stability for more details) can be simplified if the type of test configuration one considers can be simplified. For example, in the case of toric varieties, one may always take test configurations which are also toric, and this leads to a recharacterisation of K-stability in terms of convex functions on the moment polytope of the toric variety, as was observed by Donaldson in his first paper on K-stability.
In the case of Fano manifolds, it was already implicit in the work of Tian that one may restrict to test configurations with a simplified central fibre, in that case where the central fibre is a normal variety.
In this case there exists an intersection-theoretic formula for the Donaldson–Futaki invariant of a normal test configuration for . Explicitly, one extends the test configuration to a test configuration over the complex projective line trivially at the point , one has a formula
With respect to this invariant, if is a -Fano variety, we say is
K-semistable if for any normal test configuration .
K-stable if for any normal test configuration which is not isomorphic to the trivial test configuration outside a set of codimension 2.
Uniformly K-stable if for any normal test configuration , where is the minimum norm of the test configuration and is a uniform constant depending only on .
K-unstable if is not K-semistable.
According to the above definitions, there are implications
Uniformly K-stable K-stable K-semistable
The above definitions are not well-suited to the situation where the Fano variety has automorphisms. When the space of automorphisms is positive-dimensional , it was observed by Akito Futaki that there are certain test configurations constructed out of the automorphisms of which are "trivial" for the perspective of testing K-stability. In this case one should restrict to those test configurations which are equivariant with respect to the action of a maximal torus , and this leads to the notion of K-polystability or reduced K-stability. We say is
K-polystable if for any test configuration and equality holds precisely when is isomorphic to outside a set of codimension 2.
Reduced uniformly K-stable if where is the reduced -norm of the test configuration.
As for the case where the automorphism group is not positive-dimensional, we have implications
Reduced uniformly K-stable K-polystable K-semistable
The condition of uniform stability is a priori stronger than stability, because it assumes a uniform bound above zero for the Donaldson–Futaki invariant of the test configuration. However it turns out in the case of -Fano varieties uniform stability is actually equivalent to stability.
Many results can be proved more easily for uniform K-stability because a uniform bound is stronger than a non-uniform bound, so often one works with this definition as opposed to the traditional K-(poly)stability. In the more general case of a polarised variety considered in the article on K-stability it is still an open and important problem to characterise how (reduced) uniform K-stability relates to K-(poly)stability.
Special test configurations
As mentioned above, sometimes the type of test configuration to be considered can be simplified. In the case of Fano varieties, a special test configuration is a test configuration such that we have a rational equivalence of divisors for some , and the central fibre is also a -Fano variety.
One may prove that given any test configuration , there exists a special test configuration such that
This implies that for the purposes of testing the K-stability of , it suffices restrict to just looking at the above definitions of K-stability for special test configurations. The fact that one may assume the central fibre of the test configuration is also Fano leads to strong links with birational geometry and the minimal model program, providing a number of alternative characterisations of K-stability described in the following sections.
The main alternative characterisation is in terms of a different notion of Ding stability, which is a variation of the K-stability condition for the Ding invariant
where one adds on the log canonical threshold of the test configuration. The Ding invariant can only be defined in the setting of Fano varieties. Using this new invariant instead of , one can define every notion of Ding stability exactly as above, leading to Ding (semi/poly)stability and uniform versions. The Ding invariant has better formal properties with respect to algebraic geometry than the Donaldson–Futaki invariant. It is known that when a test configuration is special, the Ding invariant agrees with the Donaldson–Futaki invariant up to a constant factor, and so for Fano varieties Ding stability is equivalent to K-stability.
Alpha invariant
The first known effective criteria to test for K-stability was developed by Tian. Originally Tian's work was designed to directly provide a criterion for the existence of a Kähler–Einstein metric on a Fano manifold, and by later work it is known that every Kähler–Einstein Fano manifold is K-polystable. Tian's original definition of the alpha invariant was analytical in nature, but can be used to verify the existence of a Kähler–Einstein metric in practice.
The alpha invariant of Tian can be defined relative to a group of automorphisms , and the alpha invariant corresponds to the concept of reduced K-stability or K-polystability above. Fix a -invariant Kähler metric on a Fano manifold. Define a special class of Kähler potentials by
Then the alpha invariant is defined by
The importance of this invariant is as follows:
It was later observed by Odaka–Sano that the alpha invariant can be given a purely algebro-geometric definition in terms of an infimum of the log canonical threshold over all -invariant linear systems contained inside . Precisely, Demailly showed This allows purely algebro-geometric proofs of the existence of Kähler–Einstein metrics.
Beta invariant
The beta invariant makes close contact with birational geometry. This invariant was developed by Fujita and Li in an attempt to discover a characterisation of K-stability in terms of divisors or valuations of the Fano variety . This work was inspired by earlier ideas of Ross–Thomas which attempted to describe K-stability in terms of algebraic invariants coming out of subschemes of the variety . Whilst it is not possible to show that this "slope" K-stability is equivalent to K-stability, by passing not just to divisors inside but divisors inside any birational model over , one obtains "enough" objects to accurately test for K-stability.
In particular Fujita realised that Ross–Thomas's notion of slope K-stability was limited by only integrating up to the Seshadri constant of the subscheme, where the natural divisor on the blow-up becomes ample. By contract the -invariant integrates up to the pseudoeffective threshold where the natural divisor has positive volume (since every ample divisor has positive volume, the pseudoeffective threshold goes beyond the Seshadri constant). This extra information gives Fujita and Li's valuative criterion enough information to fully characterise K-stability.
Suppose is a normal variety with -Cartier canonical divisor . One says is a divisor over if is a divisor contained inside some normal variety such that there exists a proper birational morphism (for example given by a blow up of ). One defines the log discrepancy of a divisor over as
where is the discrepancy of the divisor in the sense of birational geometry (see canonical singularity). The discrepancy of a divisor over is defined as follows. Away from the exceptional locus of the birational morphism , the canonical divisors of and agree. Therefore, their difference is given by some sum of prime divisors contained in the exceptional locus of . That is,
where . By definition and when is not one of the prime divisors in the exceptional locus. The log discrepancy of measures the singularities of the Fano variety. In particular X is Kawamata log terminal if and only if for any over .
To define the beta invariant, one also needs the a volume term. For a divisor over , define
Here the volume of a divisor measures the rate at which its space of sections grows in comparison to the expected dimension. Namely,
where .
Finally, the beta invariant was defined by Fujita and Li as
Despite the complicated definition, due to the powerful tools of birational geometry, this invariant may be explicitly computed in practice for many classes of Fano varieties where the structure of divisors in their birational models is known. This can often be achieved with the use of computational algebraic geometry or by-hand calculation.
The relevance of the -invariant is in the following characterisation of K-stability first observed (in one direction) by Fujita and Li independently.
Delta invariant
The delta invariant can be defined as a "multiplicative" version of the "additive" beta invariant. The delta invariant of a divisor over is defined by
The delta invariant of is then given by a uniform measurement of the delta invariants of all divisors over .
The delta invariant of a divisor is conceptually similar to the beta invariant, however it was observed by Fujita–Odaka that one can compute the delta invariant as a limit of "quantized" delta invariants as . The quantized delta invariants can be computed in terms of m-basis type divisors which are given by choices of bases in the fixed finite-dimensional vector space . Thus the delta invariant is generally more computable and more theoretically powerful than its predecessors, and much progress on the explicit computations of K-stability for Fano varieties, and in the theory of moduli of Fano varieties has occurred since its introduction.
Its initial importance to the theory of K-stability is captured in the following characterisation.
The algebraic -invariant can make contact with the explicit analytical properties of Kähler–Einstein metrics. In particular, one may define the greatest Ricci lower bound as the supremum of all such that there exists a Kähler metric such that . This is the limit of how far one can traverse the natural continuity method to solve the Kähler–Einstein equation. If the greatest Ricci lower bound takes the value then one can complete the continuity method to derive the existence of a Kähler–Einstein metric. It turns out that precisely how far you can go along this continuity method, the greatest Ricci lower bound, is exactly given by the -invariant. That is,
In the case of toric Fano manifolds an even more geometric interpretation of the delta invariant was derived by Li. For such a toric Fano , the origin is always contained in the interior of the moment polytope . If denotes the barycentre of the polytope and denotes the point on the boundary of the polytope intersecting the ray , then Li showed that the greatest Ricci lower bound is given by the ratio . In particular the toric Fano has if and only if its barycentre is the origin. Interpreted using the delta invariant (and indeed using earlier results), one concludes that a toric Fano manifold is K-stable if and only if the barycentre of its polytope is the origin.
Existence of Kähler–Einstein metrics
From its initial introduction, the notion of K-stability has been intimately linked to the existence of Kähler–Einstein metrics on Fano manifolds. There are now many theorems which relate certain K-stability assumptions to the existence of solutions. These conjectures fall broadly under the title of the Yau–Tian–Donaldson conjecture. In the case of Fano varieties this conjecture asserts:For Fano manifolds this conjecture was originally proposed by Yau and Tian, and a more general form was stated by Donaldson which extends beyond just the case of Fano manifolds. Nevertheless, the conjecture even in the case of Fanos has come to be known as the Yau–Tian–Donaldson conjecture. See K-stability for more discussion of the general conjecture.
In the case of Fano manifolds, the YTD conjecture admits generalisations beyond the case of smooth varieties and forms of the conjecture are now known for singular Fanos and log Fanos.
Smooth Fano varieties
The forward direction of the conjecture, that a Fano manifold with a Kähler–Einstein metric is K-polystable, was proven by Tian in his original paper when the Fano manifold has a discrete automorphism group, that is, . This direction was proven in full generality, removing the assumption that the automorphism group was discrete, by Berman.
The reverse direction of the Yau–Tian–Donaldson conjecture was first resolved in the smooth case as stated above by Chen–Donaldson–Sun, and at the same time by Tian. Chen, Donaldson, and Sun have alleged that Tian's claim to equal priority for the proof is incorrect, and they have accused him of academic misconduct. Tian has disputed their claims. Chen, Donaldson, and Sun were recognized by the American Mathematical Society's prestigious 2019 Veblen Prize as having had resolved the conjecture. The Breakthrough Prize has recognized Donaldson with the Breakthrough Prize in Mathematics and Sun with the New Horizons Breakthrough Prize, in part based upon their work with Chen on the conjecture.The proofs of Chen–Donaldson–Sun and Tian were based on a delicate study of Gromov–Hausdorff limits of Fano manifolds with Ricci curvature bounds. More recently, a proof based on the "classical" continuity method was provided by Ved Datar and Gabor Székelyhidi, followed by a proof by Chen, Sun, and Bing Wang using the Kähler–Ricci flow.
Robert Berman, Sébastien Boucksom, and Mattias Jonsson also provided a proof from a new variational approach, which interprets K-stability in terms of Non-Archimedean geometry. Of particular interest is that the proof of Berman–Boucksom–Jonsson also applies to the case of a smooth log Fano pair, and does not use the notion of K-polystability but of uniform K-stability as introduced by Dervan and Boucksom–Hisamoto–Jonsson. It is now known that uniform K-stability is equivalent to K-stability and so BBJ's proof provides a new proof of the full YTD conjecture.
Building on the variational techniques Berman–Boucksom–Jonsson and the so-called quantized delta invariants of Fujita–Odaka, Zhang produced a short quantization-based proof of the YTD conjecture for smooth Fano manifolds.
Using other techniques entirely, Berman has also produced a proof of a YTD-type conjecture using a thermodynamic approach called uniform Gibbs stability, where a Kähler–Einstein metric is constructed through a random point process.
Singular Fano varieties and weak Kähler–Einstein metrics
The new proof of the Yau–Tian–Donaldson conjecture by Berman–Boucksom–Jonsson using variational techniques opened up the possible study of K-stability and Kähler–Einstein metrics for singular Fano varieties. The variational techniques used rely on uniform K-stability as described above.
The result of Berman that a Fano manifold admitting a Kähler–Einstein metric is K-polystable was proven in the full generality of a -log Fano pair, admitting a weak Kähler–Einstein metric. A weak Kähler–Einstein metric on a -Fano variety is a positive -current which restricts to give a smooth Kähler–Einstein metric on the smooth locus of . By requiring a compatibility with a divisor , this definition can be extended to a weak Kähler–Einstein metric on a pair .
In this generality, the reverse direction of the YTD conjecture was proven by Li–Tian–Wang in the case where the automorphism group is discrete, and in full generality by Li.By the resolution of the finite generation conjecture by Liu–Xu–Zhuang it is known that reduced uniform K-stability is equivalent to K-polystability, so combined with Berman's result the Yau–Tian–Donaldson conjecture is true in complete generality for singular Fano varieties.
Moduli spaces of K-stable Fano varieties
The construction of moduli spaces is a central problem in algebraic geometry. The construction of moduli of algebraic curves spurred the development of geometric invariant theory, stacks, and classification of algebraic surfaces has motivated results throughout algebraic geometry. The case of moduli spaces of canonically polarised varieties was settled using techniques arising from the minimal model program by Kollár–Shepherd-Barron leading to the so-called KSB moduli spaces of varieties of general type. A key property of varieties of general type which allow the construction of moduli is the lack of automorphisms of such varieties. This does not hold for Fano varieties, which can often have very large automorphism groups, so the minimal model program did not directly find applications to the construction of moduli of Fano varieties, and it became clear that K-stability was the correct algebro-geometric notion to allow the formation of moduli in this case. Moduli spaces of K-stable varieties are known as K-moduli.
Smooth case
In the case of smooth Fano manifolds, one may use techniques arising out of the Yau–Tian–Donaldson conjecture to construct the moduli space analytically. In particular work of Odaka and Donaldson building upon the ideas of Gromov compactness of Kähler–Einstein Fanos used in the proof of the YTD conjecture implies the existence of moduli spaces of smooth Fano Kähler–Einstein manifolds with discrete automorphism groups. These moduli spaces are Hausdorff and have at worst quotient singularities. By the YTD conjecture these are alternatively moduli spaces of smooth K-polystable Fano varieties with discrete automorphism groups. However, a Gromov–Hausdorff limit of smooth Fano Kähler–Einstein manifolds may lead to a singular -Fano variety, so the moduli spaces described by Odaka and Donaldson is not compact, a criterion that is often desirable in the formation of moduli spaces. One method of compactifying the moduli space of smooth K-polystable Fanos is to pass to a moduli space of singular K-polystable Fanos, and use algebraic geometry to prove its projectivity. The Yau–Tian–Donaldson conjecture for singular Fano varieties would give this compactification an alternative point of view as consisting of singular Fano varieties with weak Kähler–Einstein metrics.
General case
The standard algebraic technique to construct moduli spaces utilizes geometric invariant theory. Typically to apply Mumford's geometric invariant theory to construct moduli, one must embed a family of varieties inside a fixed finite-dimensional projective space. Such a family then defines a locus of points in the corresponding Hilbert scheme of the projective space, which is a projective scheme on which the group of projective automorphisms act. GIT stability with respect to this linearisation is called Hilbert stability. If this locus forms an open set, then GIT may be used to construct a quotient which parametrises these objects. In good circumstances this quotient may be proper and projective.
It is not always possible to embed a family of varieties inside a fixed projective space and therefore describe their moduli with geometric invariant theory, and this special property is called boundedness. A fundamental property of Fano varieties is that they fail to be bounded, and thus their stability cannot be reasonably captured by any finite-dimensional geometric invariant theory. This explains why K-stability requires one to consider test configurations for which the relatively ample line bundle can correspond to some power for arbitrarily large. However, results of Caucher Birkar showed that certain families of Fano varieties with volume bounded below form bounded families, which suggests that it may be possible to study stability of volume-bounded families of Fano varieties to form moduli spaces. For this work Birkar was awarded the Fields Medal in 2018.
It was proven by Jiang that K-semistable -Fano varieties with volume bounded below form a bounded family. Thus for a given volume there exists a uniform integer such that every K-semistable -Fano with anticanonical volume larger than or equal to admits an embedding inside the fixed projective space . The openness of this locus of K-semistable Fanos was proven by Blum–Liu–Xu and Xu. This implies the existence of an Artin stack of finite type denoted parametrising K-semistable -Fano varieties with volume bounded below by .
In order to find a genuine moduli space as a projective variety or scheme, one must prove certain properties about S-completeness and -reductivity of K-semistable Fanos inside the stack . Using properties of K-polystability, these properties of the moduli stack are true and there exists a coarse moduli space for the stack which parametrises K-polystable -Fano varieties with volume bounded below by . It was proven that is proper and that the CM-line bundle is ample, meaning the coarse moduli space is also projective. The existence result for K-moduli can be summarised in the following theorem.The construction of the moduli space of K-polystable Fanos can be generalised to the setting of log Fano varieties. The case of singular -Fano varieties which are smoothable (that is they are limits of algebraic families of smooth K-polystable Fano manifolds) was solved earlier by Li–Wang–Xu using a combination of analytic techniques, also relying on the earlier work of Odaka, Donaldson, and Codogni–Patakfalvi. There the coarse moduli space is shown to be a scheme, but in general the existence results for K-moduli only guarantee the existence of an algebraic space.
Explicit K-stability of Fano varieties
The explicit study of K-stable Fano varieties precedes the algebraic notion of K-stability, and in low dimensions was of interest purely due to the study of Kähler–Einstein manifolds. For example, either by explicit construction or the use the Tian's alpha invariant, all smooth Kähler–Einstein manifolds of dimension 1 and 2 were known before the definition of K-stability was introduced. In dimension 3 and higher explicit constructions of Kähler–Einstein metrics become more difficult, but advances arising out of the algebraic study of K-stability have enabled explicit computations of K-polystable Fano threefolds and certain families of higher dimensional varieties, and subsequently the discovery of new Kähler–Einstein manifolds.
Dimension 1
In dimension one there is a unique smooth Fano variety, the complex projective line . This variety is easily seen to be K-stable due to the existence of the Fubini–Study metric, which is a Kähler–Einstein metric, implying the K-polystability of .
A purely algebro-geometric proof of the K-stability of smooth Riemann surfaces follows from the work of Ross–Thomas on slope K-stability, which is equivalent to K-stability in dimension one. In this case one may construct test configurations out of collections of points on the curve, and when the curve is smooth no points destabilise.
Dimension 2
In dimension two the spaces which admit Kähler–Einstein metrics were classified by Tian. There are 10 deformation families of smooth Fano varieties in dimension two, the del Pezzo surfaces. Using the alpha invariant, Tian showed that a smooth Fano surface admits a Kähler–Einstein metric and is K-polystable if and only if it is not the blow up of the complex projective plane in one or two points. Thus 8 out of these 10 classes consist of K-polystable Fano surfaces.
The K-moduli of Fano surfaces were studied in explicit examples by Tian and Mabuchi–Mukai. Explicit constructions of compact moduli spaces of Kähler–Einstein Fano surfaces were achieved by Odaka–Spotti–Sun. These spaces were constructed as Gromov–Hausdorff compactifications but were identified with explicit algebraic spaces of log Fano surfaces.
For example, it is proven by Odaka–Spotti–Sun that the compact moduli space of smoothable Kähler–Einstein surfaces of degree four is given by the weighted projective space with the smooth Kähler–Einstein surfaces of degree four corresponding to the locus where is an ample divisor consisting of those points satisfying the equation .
Dimension 3
In dimension 3 purely algebraic techniques can be used to find examples of K-stable Fano varieties which are not a priori known to admit Kähler–Einstein metrics. The Iskovskikh–Mori–Mukai classification of smooth Fano threefolds provides a natural way of breaking down the problem of studying K-stable Fano threefolds into its components. It is known that there are 105 deformation families of smooth Fano threefolds, and explicit computations using Fujita–Li's beta invariant and Fujita–Odaka's delta invariant can be used to determine which deformation families contain K-stable representatives.
For every deformation family it is known whether the generic element of the family is K-(poly)stable. In particular it is known that 78 out of 105 families contain a K-polystable representative in their deformation class. For 71 out of 105 families, it is known for every single member of the deformation class whether or not it is K-polystable. For many examples of the 105 deformation families, the K-stability of representative threefolds can be interpreted in terms of a natural GIT problem which describes that family, and so explicit examples of K-moduli of Fano threefolds can also be found as GIT quotients.
For some classes of Fano threefolds the classification problem remains open. For example, it is known that the Mukai–Umemura threefold in the deformation class admits a Kähler–Einstein metric and is therefore K-polystable by work of Donaldson, who computed Tian's alpha invariant explicitly using the criterion above. This manifold has non-discrete automorphism group and which nearby deformations of are also K-polystable is not known. It is conjectured that the deformations corresponding to GIT-polystable points within the versal deformation space of should correspond to nearby K-polystable varieties.
Higher dimensions
The first and simplest example of a K-polystable Fano manifold in any dimension is complex projective space, which always admits the Fubini–Study metric which is Kähler–Einstein in any dimension and therefore all projective spaces are K-polystable.
In general there are not many such "obvious" Kähler–Einstein metrics in higher dimensions, and one must use recent techniques of stability to find examples. For certain families of Fano varieties, K-stability can be proved in higher dimensions using either analytic techniques through the alpha invariant or purely algebro-geometric techniques with the beta or delta invariants. As an example, a Fermat hypersurface is a variety of the form
These hypersurfaces are smooth Fano manifolds with discrete automorphism group for , and it was proven by Tian using the alpha invariant that implying admits a Kähler–Einstein for , and using more detailed arguments Tian proved the existence of a Kähler–Einstein metric when . On the other hand, using the delta invariant Zhuang gave a completely algebraic proof that is K-stable for and therefore admits a Kähler–Einstein metric in these cases. Using the openness results for uniform K-stability and K-semistability, one can conclude from this that the generic smooth hypersurface of degree inside is K-stable. In some cases it is in fact known that all degree hypersurfaces are K-stable, such as all smooth hypersurfaces in .
In addition to the study of particular Fano varieties, in certain settings K-moduli may be explicitly described in higher dimensions. For example, when the K-moduli admits an "obvious" GIT interpretation, the algebraic tools of beta or delta invariants can be used to verify that GIT stability is equivalent to K-stability for that particular problem. For example, Liu showed that for cubic fourfold hypersurfaces in , the GIT moduli space of (possibly singular) cubic fourfolds is isomorphic to the K-moduli space, and thus one obtains an explicit description of the K-stable, K-polystable, and K-semistable cubic fourfolds in terms of their GIT stability and singularity structure. In particular every smooth cubic fourfold is K-stable.
References
Notes
Algebraic geometry | K-stability of Fano varieties | [
"Mathematics"
] | 6,936 | [
"Fields of abstract algebra",
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70,175,808 | https://en.wikipedia.org/wiki/Deterministic%20Barcoding%20in%20Tissue%20for%20Spatial%20Omics%20Sequencing | Deterministic Barcoding in Tissue for Spatial Omics Sequencing (DBiT-seq) was developed at Yale University by Rong Fan and colleagues in 2020 to create a multi-omics approach for studying spatial gene expression heterogenicity within a tissue sample. This method can be used for the co-mapping mRNA and protein levels at a near single-cell resolution in fresh or frozen formaldehyde-fixed tissue samples. DBiT-seq utilizes next generation sequencing (NGS) and microfluidics. This method allows for simultaneous spatial transcriptomic and proteomic analysis of a tissue sample. DBiT-seq improves upon previous spatial transcriptomics applications such as High-Definition Spatial Transcriptomics (HDST) and Slide-seq by increasing the number of detectable genes per pixel, increased cellular resolution, and ease of implementation.
Applications
In multicellular systems the function of each individual cell is impacted by their spatial location and surroundings. Thus, implementation of DBiT-seq to profile both mRNA and protein levels across a tissue in a spatial context could lead to a better understanding of many biological processes. DBiT-seq can be utilized across many different fields such as oncology, developmental biology, and pathology. Use in developmental biology may lead to a better understanding of how organogenesis occurs, and in oncology it may provide more insight into the role of heterogeneity in tumorigenesis and progression.
Methodology
DBiT-seq uses a microfluidics system to deliver oligonucleotide barcodes in a precisely controlled pattern. The system applies two sets of oligonucleotide barcodes (A1 – A50 and B1 – B50) perpendicularly to produce a grid of unique barcodes across the section labelled A1B1, A1B2 and so on.
Device preparation
DBiT-seq requires a specially crafted microfluidics device to deliver the barcodes. Microfluidics enables the precise manipulation of fluids on the micron scale. The DBiTseq device is prepared using polydimethylsiloxane (PDMS) cast in a silicon wafer mold. The device allows the user to deposit the liquid reagents into appropriate channels on a macro scale with no special equipment. These reagents are then drawn by vacuum through the 10, 25, or 50 μm wide channels across the surface of the tissue section.
The other components of the DBiT-seq device are two PDMS reservoirs and an acrylic clamp system to hold the device flush to the tissue.
Tissue preparation and antibody staining
An advantage of DBiT-seq is the ability to use it on tissue slides preserved with formaldehyde in a process known as tissue fixing, which is incompatible with other spatial omics methodologies. Tissues are frozen, fixed and sectioned into very thin slices which are mounted on glass slides. If information about proteins in the sample is desired, the tissue is first stained with antibody-derived DNA tags (ADTs). ADTs are made up of an antibody conjugated to an oligonucleotide containing a unique barcode sequence and a Poly-A tail sequence. The Poly-A tail will be recognized by the Poly-T sequence on barcode A, enabling it to be associated with a spatial location.
Barcoding
Following antibody staining (if desired), the first set of 50 barcodes are applied to the tissue sample using the first microfluidics chip. Each 'A' primer contains a unique barcode sequence, a ligation linker, and a poly T sequence. The poly-T sequence binds to the poly-A tail on mRNAs in the tissue sample and on the ADTs applied earlier. Reverse transcription then generates the first cDNA strand containing the barcode and mRNA or antibody tag sequence. Chip B is then applied to the same tissue slide. Chip B will deliver the second set of barcodes perpendicular to the first, creating a grid pattern. Each 'B' oligonucleotide contains a unique barcode sequence, a PCR handle, a ligation linker, and biotin for cDNA purification. The ligation linker sequences are used to ligate barcodes A and B together into a single DNA strand. Finally, a lysis step extracts the cDNA from the tissue into a pooled sample containing all of the barcoded strands.
Library preparation and sequencing
The cDNA lysate produced in step 3 is purified using streptavidin beads that recognize the biotin on barcode B. The complementary cDNA strand is then synthesized by reverse transcription, followed by PCR amplification and final purification of the library. The library is then sequenced using next-generation (Illumina) sequencing.
Data analysis
The tissue slide is imaged before, during, and after each barcoding step to enable precise association of spatial information obtained from the barcodes. Associating the barcodes with each mRNA sequence provides a spatial transcriptomics map of the tissue. While this is not a single-cell methodology, the 10 uM channels capture only 1-2 cells per square, generating near-single-cell resolution. The ADT sequences capture spatial proteomic information that can be compared to the transcriptomic data. Specific cell populations can be identified in two ways. First, by matching the transcriptome to previous single-cell RNA-seq (scRNA-seq) profiles for each cell type. Second, using spatial differential expression (SpatialDE), a pattern recognition software that can differentiate tissue types without scRNA-seq data.
Advantages and limitations
Advantages
DBiT-seq provides an advantage over other spatial-omics techniques by allowing the co-mapping of mRNAs and proteins. This provides both transcriptomic and proteomic data for analysis. The technique can be easily implemented and adapted to researcher's needs and proteins of interest. This method can be used successfully on H&E and immunostained tissue samples, as well as with formaldehyde-fixed tissue samples. The channels used for barcoding can be changed to adjust for resolution requirements from 10 μm, 25 μm, and 50 μm.
Limitations
The resolution of DBiT-seq does not have single cell resolution, but it is near single cell resolution. The pixel size has a theoretical limit of ~5 μm, which is small enough to allow for single or fraction of a single cell observation but has not been implemented. With the current channel configurations there is a size limitation to mapping area on a tissue, using 10 μm channels this allows for only a 1 mm × 1 mm area of the tissue to be mapped. To overcome this limitation additional barcoding channels could be added to increase area covered.
Summary
Tissues are made of heterogeneous populations of cells. Understanding how these cells work together and the role of each cell type in the tissue is important in fields such as cancer research and developmental biology. While advances in single cell omics technologies have improved our effort to understand these complex environments, spatial information has been notably lacking. This has been improved by the advent of spatial omics. DBiT-seq provides an accessible method to obtain spatial transcriptomic and proteomic information from fixed or fresh tissue sections. With 10, 25 or 50 μm resolution, DBiT-seq provides near single cell resolution and provides spatial omics data without the need for highly specialized imaging equipment.
References
Omics
DNA barcoding | Deterministic Barcoding in Tissue for Spatial Omics Sequencing | [
"Biology"
] | 1,528 | [
"Genetics techniques",
"DNA barcoding",
"Bioinformatics",
"Omics",
"Molecular genetics",
"Phylogenetics"
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70,178,444 | https://en.wikipedia.org/wiki/Thraustochytrids | Thraustochytrids are single-celled saprotrophic eukaryotes (decomposers) that are widely distributed in marine ecosystems, and which secrete enzymes including, but not limited to amylases, proteases, phosphatases. They are most abundant in regions with high amounts of detritus and decaying plant material. They play an important ecological role in mangroves, where they aid in nutrient cycling by decomposing decaying matter. Additionally, they contribute significantly to the synthesis of omega-3 polyunsaturated fatty acids (PUFAs): docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), which are essential fatty acids for the growth and reproduction of crustaceans. Thraustochytrids are members of the class Labyrinthulea, a group of protists that had previously been incorrectly categorized as fungi due to their similar appearance and lifestyle. With the advent of DNA sequencing technology, labyrinthulomycetes were appropriately placed with other stramenopiles and subsequently categorized as a group of Labyrinthulomycetes.
There are several characteristics which are unique to Thraustochytrids, including their cell wall made of extracellular non-cellulosic scales, zoospores with characteristic heterokont flagella, and a bothrosome-produced ectoplasmic net, which is used for extracellular digestion. Thraustochytrids are morphologically variable throughout their life cycle. They have a main vegetative asexual cycle, which can vary depending on the genus. While sexual reproduction has been observed in this group, it remains poorly understood.
Thraustochytrids are of particular biotechnical interest due to their high concentrations of docosahexaenoic acid (DHA), palmitic acid, carotenoids, and sterols, all of which have beneficial effects to human health. Thraustochytrids rely on a plethora of resources such as various sources of organic carbon (vitamins and sugars), and inorganic salts throughout their life cycle. Scientists have devised several potential uses for thraustochytrids stemming around increasing DHA, fatty acids, and squalene concentrations in vivo by either changing the genetic makeup or medium composition/conditioning. There have also been some breakthroughs which have resulted in gene transfers to plant species in order to make isolation of certain oils easier and cost effective. Thraustochytrids are currently cultured for use in fish feed and production of dietary supplements for humans and animals. In addition, scientists are currently researching new methodologies to convert waste water into useful products like squalene, which can then be utilized for the production of biofuel.
Morphology
As labyrintulomycetes, thraustochytrids share distinct characteristics with other organisms in this group. These include, but are not limited to: biflagellate zoospores which have an anterior flagellum containing mastigonemes, a bothrosome-produced ectoplasmic net, and multilamellate cell walls with scales derived from Golgi bodies. Thraustochytrids are single-celled protists, characterized with only one sporangium (monocentric), an ectoplasmic net, and a multi-layered, non-cellulosic cell wall made of overlapping circular scales. Despite often being referred to as algae, they do not have a plastid, making them obligate heterotrophs.
At their vegetative state, thraustochytrids measure 4 to 20 μm in diameter and are globose or subglobose in shape. They have a multi-layered cell wall made of sulphated galactose. The singular sporangium of thraustochytrids is typically ovular or spherical in shape, and varies across genus. In the Botryochytrium genus, for example, the shape of the zoosporangium was compared to a grape. Thraustochytrids have biflagellate zoospores with heterokont flagella typical of other Stramenopiles. On the posterior end, the whiplash is short, and on the anterior end, a long tinsel flagellum protrudes.
Ultrastructure
Within the granular cytoplasm lies single dictyosomes, centrioles, endoplasmic reticulum, mitochondria, and lipid bodies in some cases. Thraustochytrids contain many mitochondria, which are polymorphic and have tubular cristae. Made of sulphated polysaccharides, the cell wall of thraustochytrids are multilamellate and non-cellulosic. The cell wall is derived from the dictyosome cisternae during thallus development, where circular scales (vesicles) form on the basal membrane to merge. In thraustochytrids, the cell wall is rich in galactose and xylose.
Characteristic of thraustochytrids is their ectoplasmic net—which is an extension of the plasma membrane —emerging from the bothrosome (also known as the sagenogenetosome, or SAG). The cytoplasmic net is unilateral, motile, and resembles fine fibres when viewed under a scanning electron micrograph. Depending on the genus, they may be branched or unbranched, and are thought to originate from a single trunk or organelle. Ectoplasmic nets have the capacity to excrete hydrolytic enzymes (cellulases, amylases, lipases, phosphatases, and/or proteases) to digest organic material in the water, thus assuming the role of decomposition. In lab settings, the endoplasmic net of thraustochytrids has been shown the ability to penetrate the sporopollenin of pine pollen, which comprises a polymer that is highly resistant to microbial degradation. This experimental process is called pollen-baiting. Beyond decomposition, ectoplasmic nets also participate in providing adhesive function, as well as assimilation of digested organic material (absorption).
Life cycle
The life cycle of thraustochytrids is generally complicated, differing from genus to genus, and typically consisting of multiple stages of cell types such as zoosporangia, multinucleated cells, mononucleated cells, and amoeboid cells.
Asexual reproduction
All thraustochytrids undergo a main vegetative life cycle, beginning as a mononucleated cell that undergoes nuclear division to become multinucleated and maturing into a sporangia which release zoospores to begin the cycle again. Branching off of the main vegetative life cycle, additional paths can be taken based on the strain. Traustochytrids undergo cell division in two main ways: through a zoosporangium or through successive bipartition. These methods can occur in the same species and at different stages of the lifecycle. When cell division occurs through the formation of a zoosporangium, the nuclei divide within a single cell to create a multinucleate cell which becomes a zoosporangium following progressive cleavage. When cells divide through successive bipartition, the cell divides immediately after nuclear division, either by invagination of the plasma membrane or fusion with internal vesicular membranes. Thraustochytrids undergo open mitosis, meaning that the nuclear membrane breaks down during cell division, and then reforms following nuclear division.
Amoeboid loop
Certain strains of thraustochytrid are able to enter an amoeboid loop from multiple vegetative life cycle stages, gaining an advantage of being able to move slowly across surfaces as either mononucleated or multinucleated amoeboid cells. Ulkenia, Schizochytrium, Hondaea, and Aurantiochytrium can undergo binary division to form a cluster of mononucleated cells which can then turn into amoeboid cells and enter an amoeboid loop. The amoeboid loop can also be entered from mononucleated cells directly turning into mononucleated amoeboid cells or multinucleated cells and sporangia directly turning into multinucleated amoeboid cells. Strains in the amoeboid loop eventually have to re-enter the main vegetative life cycle in order to produce zoospores.
Sexual reproduction
Although the details of sexual reproduction are poorly understood, vegetative cells are thought to be diploid and undergo meiosis to form a sporangium, which releases gametes. While syngamy has been observed in Aurantiochytrium acetophilum, the fate of the zygote is relatively unknown, however, it is suspected that they enter the vegetative cycle as a mononucleated cell.
Taxonomy
Thraustochytrids were first reported by F.K. Sparrow in 1934. Like other Labyrinthulomycetes, they were classified as fungi due to their ectoplasmic nets and ability to produce zoospores. However, the morphological plasticity of thraustochytrids prevents them from being accurately classified based on their appearance. It was not until 1973 that Sparrow reclassified them as oomycetes, indicating that they were stramenopiles and not fungi. In the years that followed, scientists began to perform concurrent morphological and molecular genetics studies to further explore the placement of thraustochytrids. Using ribosomal RNA as a phylogenetic marker, Cavalier-Smith et al. provided strong molecular evidence that indicated thraustochytrids were not closely related to fungi or oomycetes. Other studies supported these findings by highlighting morphological similarities between thraustochytrids and other labyrinthulomycetes. While the phylogeny of thraustochytrids is still relatively unresolved, they have been clearly defined taxonomically. Thraustochytrida is one of two orders in the class Labyrinthulea and the nomenclature in this group is highly variable due to its history of being considered fungi.
Ecology
Distribution
Thraustochytrids have been found in various habitats such as tropical coasts in the Indian Ocean, Pacific Ocean, and the Northern Arabian sea; temperate and cold waters in Australia, Argentina, the Mediterranean Sea, and the North sea; and subantarctic, antarctic, and subarctic waters. Overall, thraustochytrids are widespread in marine waters. They can be found all the way through the photic, euphotic, and aphotic zones. The ideal salinity range for this protist is ~20‰-30‰; however they are euryhaline and can survive at a salinities as low as 12‰. Since they require a specific concentration of salt to survive, they are categorized as halophilic protists.
Living conditions
Additionally, they require sodium to live and this cannot be substituted by potassium. They are found at a higher frequency in systems that have large amounts of detritus along with decaying plant material. Areas of note include mangroves, salt marshes, and river output zones. Thraustochytrids gain a significant amount of nutrients for growth from any form of decaying organic matter and, as a result, can thrive in areas with elevated pollution or rich in organic material. They can be found on materials either indigenous (autochthonous) or that has been transported there (allochthonous). They are not commonly found on living organisms, and if they are, it is sporadic and in low concentrations. The reasoning for this is suspected to be due to plants being able to release antimicrobial compounds to prevent them from being colonized by microorganisms. In the early stages of decomposition, there are low observed numbers of thraustochytrids as there are still materials that inhibit growth on the organism.
As decomposition progresses, thraustochytrids rapidly populate the substrate. In studies involving mangroves, the thraustochytrids on the leaves would produce the enzymes cellulase, amylase, xylanase, proteases, and pectinases, which suggest that they can play a role in the chemical processes taking place. There have been cases of thraustochytrids being cultured from algal surfaces but only in low numbers. Notably, in a case of culturing thraustochytrids on the brown alga Fucus serratus, they were found to be in low numbers potentially due to inhibitory material being secreted by the alga. A 1992 experiment found that thraustochytrids could not be cultured on the green algae Ulva fasciata and Valoniopsis pachynema. These two algae contain high amounts of phenolic compounds, which is believed to be the reason.
Parasitism
There is a lack of concrete evidence regarding parasitic relationships with plants, however studies have found such relationships with invertebrates. In the case of the octopus Eledone cirrhosa, there were found to be ulcerative lesions that could be contagious to other marine organisms. Thraustochytrids could not confidently be determined as the cause of these fatal lesions, with a suggestion being that they came into contact with octopuses after initial infection. Other discoveries of infections similar to what befell Eledone cirrhosa have been noted on oysters, farmed rainbow trout, squid gills, sponges, free living flat worms, cnidarians nudibranchs, and tunicates.
Examining cases of parasitic relationships between thraustochytrids and living organisms, the protist can be either the direct cause of disease to the host or an opportunistic parasite. It is unclear what allows for thraustochytrids to act as a pathogen, however, it appears to be a combination of environmental factors and there being an issue with the host organisms pathogenic defence mechanisms such as being unable to excrete any inhibitory materials.
Other biotic relationships
Studies have found significant amounts of thraustochytrids in the stomach contents and feces of Lytechinus variegatus, a sea urchin. This discovery could be due to either ingestion of detritus, containing thraustochytrids or it could potentially be a regular component of the sea urchin species’ stomach. A species of thraustochytrid, Ulkenia visurgensis have also been found in healthy cnidarians in Indian tidal pools using immunofluorescence. Large amounts of the protist have also been discovered in the feces of the salp Pegea confoederata. These discoveries suggest that there is a relationship between thraustochytrids and the invertebrates mentioned, as well as potentially others in marine environments. Barnacle larvae were also found to survive and grow on substrates where thraustochytrids lived compared to surfaces without, potentially indicating a relationship between the two.
Role in marine food webs
Thraustochytrids play a large role in marine food webs with a significant contribution being in their synthesization of omega-3 polyunsaturated fatty acids (PUFAs): docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) which are essential for marine crustaceans. Their main contributions of these fatty acids to the marine food chain occur in environments where they are able to thrive, usually in areas of high particular detritus in the water column. The PUFAs produced specifically enable growth and reproduction in the crustaceans. Bacteria do not synthesize significant amounts of PUFAs and zooplankton synthesis rates are usually less than 2% of what is required, suggesting that the main source of these fatty acids for them are found further down the food chain and are incorporated into their body from thraustochytrids they feed on. The synthesization of these fatty acids is also important for organisms at higher trophic levels.
Physiology
Since thraustochytrids are obligate heterotrophic protists (non-photosynthetic microalgae), they obtain most of their resources for growth from decaying matter. To act as decomposers, thraustochytrids have evolved to encompass a wide variety of hydrolytic enzymes which include: amylases, proteases, phosphatases, cellulases, lipases, ureases, gelatinase, chitinase, and α-glucosidase. These hydrolytic enzymes are either deposited at the ECM or secreted to the surrounding solution. Ectoplasmic nets have the capacity to excrete hydrolytic enzymes (cellulases, amylases, lipases, phosphatases, and/or proteases) to digest organic material in the water, thus assuming the role of decomposition. In lab settings, the endoplasmic net of thraustochytrids has been shown the ability to penetrate the Pine pollen's sporopollenin, which is a highly microbial-resistant polymer. This experimental process is called pollen-baiting. Beyond decomposition, ectoplasmic nets also participate in providing adhesive function, as well as assimilation of digested organic material (absorption).
Thraustochytrids rely on a wide array of inorganic material for growth such as monopotassium phosphate, sodium chloride, and sodium sulfate. Absence of ions such as potassium can stunt thraustochytrid growth. More specifically, the absence of sodium ions could prevent the uptake of inorganic phosphate that is required for large scale growth conditions. In addition, some species of thraustochytrids can utilize urea as a nitrogen source for growth via a hydrolytic process, which ultimately yields carbon dioxide and ammonia.
In terms of organic carbon sources, thraustochytrids are capable of harnessing organic carbon compounds like maltose, fructose, sucrose, glucose, glycerol, and ethanol for energy expenditure and growth. In addition, vitamins such as thiamine, biotin, cobalamin, nicotinic acid, pantothenic acid, and riboflavin are utilized as well.
Hong Kong isolates of thraustochytrids species have displayed a wide range of pH for proper growth extending from 4 to 9, however, each individual species exhibited a different range of pH optima. In addition, these Hong Kong isolates tend grow within a temperature range of 20-25 °C, with salinity levels ranging around 7.5-30‰. However, just like the pH ranges, the optima range of temperature and salinity exhibited by each species differed from one another.
Major compounds synthesized
Roughly greater than 65% of fatty acids that constitute thraustochytrids' membranes stem from DHA (22:6) and palmitic acid (16:0). Through unestablished physiological means, thraustochytrids sustained in an environment lacking nitrogen will initiate the synthesis of lipids. It is believed that limitations induced by nitrogen deficiency within the medium can pause cell division, which causes a change in the carbon flux that is used to maintain membrane and protein synthesis and ultimately promotes the production of TAGs. In terms of overall lipid composition, neutral lipids which are mainly constituted of TAGs make up a large portion of glycerolipid distribution relative to polar lipids.
Saturated fatty acids and polyunsaturated fatty acids
The production of saturated fatty acids and polyunsaturated fatty acids takes place via two pathways which require a type I Fatty Acid Synthase (FAS) construct and a Polyketide Synthase-like (PKS-like) machinery (a.k.a. PUFA synthase), respectively. FAS gives rise to saturated fatty acids that are 16 carbons in length via an aerobic pathway. On the other hand, PUFA synthase gives rise to unsaturated fatty acids that are 20 and 22 carbons in length via an anaerobic pathway. FAS typically produces an abundance of palmitic acid (16:0), while PUFA synthase typically produces an abundance of DHA (22:6). It is not certain as to why two different pathways are needed for fatty acid synthesis, but studies have shown that auxotrophic thraustochytrids are a direct result of mutations to the PUFA synthase, thus indicating that the two pathways are not redundant and are independent of one another. It has been reported that if the DH/I domain of PUFA synthase's subunit C is mutated, it will lead to a decrease of greater than 50% to the overall yield of PUFA, thus, indicating its importance to the synthetic pathway and possible exploitation.
Synthesis of DHA
Acetyl-CoA first attaches to KS releasing CoA-SH, then MAT adds a malonyl group to ACP while releasing CoA-SH as a byproduct. KS condenses the activated acetyl with the malonyl group to produce acetoacetyl-CoA, releasing CO2 as a byproduct. KR then reduces acetoacetyl-CoA via NADPH + H+ and the subsequent product is dehydrated via a DH or DH/I dehydratase to produce an acyl chain with a 2-trans double bond (trans-∆2-butenoyl-ACP). The 2-trans double bond may then be reduced via ER utilizing NADPH + H+ (FAS pathway continuation) or isomerized via DH/I leading to a 2,3 or 2,2 trans-cis product (PUFA synthase pathway continuation). The cycle may repeat several times with the addition of two more carbons via either pathway to yield an elongated fatty acid or a precursor to PUFA 22:6 (DHA) through CLF (chain length factor) domain processing. It has been reported that the type of DH dehydratase utilized dictates the process towards PUFA 22:6 (DHA) synthesis, which is ultimately determined via the length of an already growing acyl chain.
Synthesis of sterols and carotenoids
To form mevalonate (a precursor to sterols and carotenoids), two acetyl-CoAs combine to form acetoacetyl-CoA, then another acetyl-CoA is added to form HMG-CoA. With the utilization of two NADPH + H+, mevalonate forms. Mevalonate then undergoes three series of reactions with one ATP dedicated to each to form mevalonate-5-PP. Mevalonate-5-PP then loses CO2 and Pi to from ∆3-isopentenyl pyrophosphate, which can isomerize to dimethylallyl pyrophosphate. With the addition of both these components in a head-to-tail condensation, geranyl pyrophosphate can either lead to the synthesis of carotenoids and or sterols via their intermediary product – farnesyl pyrophosphate. Continuing towards sterols, geranyl pyrophosphate with ∆3-isopentenyl pyrophosphate in a head-to-tail condensation will lead to the production of farnesyl pyrophosphate. Farnesyl pyrophosphate then combines with another farnesyl pyrophosphate via utilization of NADPH + H+ to produce squalene (via squalene synthase) – the major precursor to sterol synthesis.
Applications
Thraustochytrids produce lots of docosahexaenoic acid (DHA). When cultivated under certain conditions, some thraustochytrids can have their total weight composed of 15-25% DHA. DHA has been reported to have many benefits such as decreasing the onset of depression, having anti-inflammatory properties, decreasing the onset of memory loss via proper neuronal cell development (especially in infants), and many more. Thraustochytrids are also capable of producing carotenoids and sterols, which have been linked to decreasing diseases such as coronary heart disease, cancer, and osteoporosis. Furthermore, squalene can be extracted from thraustochytrids, which has benefits linked to activating non-specific immune responses, cancer remedies, UV ionization cell damage reduction, and the capability of acting as an exogenous antioxidant.
Potential uses
Thraustochytrids have the potential to overturn exploitation of fish stocks as a new form of sustainable commercial oil producers, while also minimizing losses caused by toxic environmental exposures. This can be accomplished by depriving cells from nitrogen, therefore, triggering the production of DHA. More specifically, a two-stage fermentation protocol could be utilized to accomplish this task. Cells are first grown within a low C:N (high nitrogen content) ratio medium, and then replaced with a high C:N (low nitrogen content) ratio medium, which subsequently prompts an increase in both DHA and FAs yields. If a vast number of 15:0 fatty acids is desired, the low nitrogen medium could be supplied with a surplus of branched amino acids such as valine, isoleucine, leucine.
Squalene (a precursor to sterols) is used to improved human health as a drug delivery system, and a moisturizing agent which is typically derived from shark liver oil. With an increase in demand for squalene over time, sharks are faced with a major decline in population size. Thus, an incentive for a new form of squalene production was generated, and Aurantiochytrium seems to be a viable solution to this problem.
Scientists have genetically engineered several pathways to increase thraustochytrids’ yield of beneficial products by creating mutants, overexpressing genes, and or introducing knock-ins. Some experiments had significant results such as producing a 1.5-3-fold increase in fatty acid production, a 2-9 fold increase in astaxanthin production, a 4 fold increase in EPA (20:5) production, and a 2.5-3 fold increase in DHA quantity. Recent data has shown that if Aurantiochytrium limacinum SR21 are kept at 50% dissolved oxygen levels within their growth medium, then large increases in both biomass and DHA levels are observed. Other studies and a patent have shown that light could be used to increase biomass, carotenoids, and DHA through either constant or discontinuous illumination using different wavelengths.
Addition of terbinafine hydrochloride and jasmonate to cultures containing certain thraustochytrids strains like Aurantiochytrium mangrovei FB3 and Schizochytrium mangrovei, respectively, have demonstrated an increase in squalene production which could be utilized for sterol synthesis. Supplementation of calcium and magnesium ions helped thraustochytrids strains Aurantiochytrium sp. DBTIOC-18 and Schizochytrium sp. DBTIOC-1 to grow under a highly concentrated glycerol medium which typically inhibits growth, and thus gave rise to greater biomass, fatty acid, and DHA production rates.
Extracellular lipases have also been induced in two thraustochytrids strains displaying optimal activity at basic pH, thus giving rise to potential detergent usage. Some scientists have also demonstrated that thraustochytrids could be used to make antigens to fight against influenza and other types of viruses. In addition, gene transfers into plant seeds have been successful, thus allowing for the overexpression of PUFA synthase. As a result, these seeds can have their oils isolated and extracted for possible downstream commercial sale.
The temperature and or seasons have been reported to alter the fatty acid composition of thraustochytrids isolated from India. Winter isolates depicted a large increase in DHA content which are useful towards nutraceutical applications, while summer isolates depicted a large increase in omega three fatty acids and compounds directly related to biodiesel formulation.
Industrial uses
Companies such as Royal DSM, Alltech, Martek Bioscience, and Ocean Nutrition Canada currently utilize thraustochytrids in some form to produce dietary supplements fit for human and animal consumption. Food products such as eggs, meat, milk, and baby formula are some of the many examples of products enriched with omega-3 fatty acids derived from thraustochytrids. Many of these products are certified as harmless towards human health by the FDA and European Commission.
Thraustochytrids oils have been used to feed aquaculture such as Atlantic salmon, juveniles of giant grouper, longfin yellowtail, catfish, and salmon parr. It been reported that rotifers are supplemented with polyunsaturated fatty acids using a schizochytrium strain, which are subsequently fed to finfish larvae. Studies have shown that commercial fish supplemented with DHA during the spawning season tend to grow faster and have greater survival rates with reduced abnormalities. Astaxanthin, a keto-carotenoid, derived from thraustochytrids have also been used to feed fish, chicken, and turkey, and to even dye food.
Thraustochytrids have also made some break throughs in the biofuel industry. Strains such as Schizochytrium sp. S31 and Schizochytrium mangrovei PQ6 have demonstrated good potential towards the production of certain fuel compounds like biodiesel. The Japanese have also developed a new strain of thraustochytrid, Aurantiochytrium 18 W13a, which is capable of producing squalene from sludge waste water. Using ruthenium/cerium oxide catalysis, squalene is then turned into small chain alkanes which can be subsequently used in the production of industrial and commercial fuel. Scientists have also engineered a new thraustochytrid strain (T18) that can feed on hemi-cellulosic waste generated from feedstocks, and thus produce useful lipids. This was accomplished via overexpressing heterologous xylulose kinase and endogenous xylose isomerase.
A European patent has also demonstrated the capability of oils sourced from thraustochytrids being used towards the creation of thermal insulators.
References
Wikipedia Student Program
Bigyra
Marine microorganisms | Thraustochytrids | [
"Biology"
] | 6,411 | [
"Marine microorganisms",
"Microorganisms"
] |
70,179,173 | https://en.wikipedia.org/wiki/TX%20Ursae%20Majoris | TX Ursae Majoris is an eclipsing binary star system in the northern circumpolar constellation of Ursa Major. With a combined apparent visual magnitude of 6.97, the system is too faint to be readily viewed with the naked eye. The pair orbit each other with a period of 3.063 days in a circular orbit, with their orbital plane aligned close to the line of sight from the Earth. During the primary eclipse, the net brightness decreases by 1.74 magnitudes, while the secondary eclipse results in a drop of just 0.07 magnitude. TX UMa is located at a distance of approximately 780 light years from the Sun based on parallax measurements, but is drifting closer with a mean radial velocity of −13 km/s.
In 1931, H. Rügemer and H. Schneller independently discovered this is an eclipsing binary system of the Algol type. Rügemer later found that the eclipse period was not constant, a behavior that was subsequently explained as apsidal precession. B. Cester and associates in 1977 confirmed this is a semidetached binary system consisting of a main sequence primary star and an evolved giant companion. A study of the system by J. M. Kreiner and J. Tremko in 1980 disproved that changes in the eclipse period are due to apsidal motion.
The light curve of this system shows little impact from proximity effects between the two stars, making it only weakly interacting. The primary eclipse is very deep with less than 5% of the brighter star's light appearing at central eclipse, allowing the spectrum of the fainter secondary to be directly examined. In addition to a steady decrease in the system orbital period, multiple irregular changes in the period were observed between 1903 and 1996. The slowing orbit may be due in part from magnetic breaking of the mass-donor secondary, causing a transfer of angular momentum to the system. An accretion disk may be a contributing factor. Spectral evidence supports an accretion disk in orbit around the primary that is sustained by mass transfer. A faint emission from the system is evidence of a circumbinary ionized shell.
The cooler secondary component is the more evolved member of the pair with a stellar classification of G0III-I, having previously exhausted the supply of hydrogen at its core and evolved off the main sequence. This star has filled its Roche lobe and is contributing mass to the primary. It now has 1.2 times the Sun's mass but has expanded to 4.2 times the solar radius. The secondary is rotating synchronously with its orbit. The primary component of this system is a B-type main-sequence star with a stellar classification of B8V. It is rotating 1.5 times as fast as the orbital rate due to the impact of mass accretion from the secondary. The primary has 4.8 times the mass and 2.8 times the radius of the Sun.
References
Further reading
B-type main-sequence stars
G-type giants
Algol variables
Binary stars
Ursa Major
BD+30 2162
093033
052599
Ursae Majoris, TU | TX Ursae Majoris | [
"Astronomy"
] | 649 | [
"Ursa Major",
"Constellations"
] |
70,179,999 | https://en.wikipedia.org/wiki/Suita%20conjecture | In mathematics, the Suita conjecture is a conjecture related to the theory of the Riemann surface, the boundary behavior of conformal maps, the theory of Bergman kernel, and the theory of the L2 extension. The conjecture states the following:
It was first proved by for the bounded plane domain and then completely in a more generalized version by . Also, another proof of the Suita conjecture and
some examples of its generalization to several complex variables (the multi (high) - dimensional Suita conjecture) were given in and . The multi (high) - dimensional Suita conjecture fails in non-pseudoconvex domains. This conjecture was proved through the optimal estimation of the Ohsawa–Takegoshi L2 extension theorem.
Notes
References
Several complex variables
Algebraic geometry | Suita conjecture | [
"Mathematics"
] | 157 | [
"Functions and mappings",
"Mathematical analysis",
"Mathematical analysis stubs",
"Several complex variables",
"Mathematical objects",
"Fields of abstract algebra",
"Mathematical relations",
"Algebraic geometry"
] |
70,180,406 | https://en.wikipedia.org/wiki/Psoromic%20acid | Psoromic acid is a β-orcinol depsidone with the molecular formula C18H14O8. Psoromic acid inhibits herpes simplex viruses type 1 and type 2. Furthermore, it inhibits the RabGGTase. Psoromic acid occurs in antarctic lichens.
References
Further reading
Lichen products
Heterocyclic compounds with 3 rings
Oxygen heterocycles
Carboxylic acids
Lactones
Ketones
Hydroxyarenes
Methoxy compounds | Psoromic acid | [
"Chemistry"
] | 104 | [
"Natural products",
"Lichen products",
"Ketones",
"Carboxylic acids",
"Functional groups"
] |
70,180,544 | https://en.wikipedia.org/wiki/Phalaenopsis%20%C3%97%20veitchiana | Phalaenopsis × veitchiana is a species of orchid endemic to the Philippines. It is a hybrid of Phalaenopsis equestris and Phalaenopsis schilleriana. It occurs naturally and has also been artificially re-created. It is named after the British horticulturalist Harry J. Veitch.
References
veitchiana
Orchid hybrids
Hybrid plants
Plant nothospecies
Interspecific plant hybrids | Phalaenopsis × veitchiana | [
"Biology"
] | 88 | [
"Hybrid plants",
"Plants",
"Hybrid organisms"
] |
70,180,865 | https://en.wikipedia.org/wiki/Die%20shot | A die shot or die photography is a photo or recording of the layout of an integrated circuit, showings its design with any packaging removed. A die shot can be compared with the cross-section of an (almost) two-dimensional computer chip, on which the design and construction of various tracks and components can be clearly seen. Due to the high complexity of modern computer chips, die-shots are often displayed colourfully, with various parts coloured by diffraction within the parts of the die, using special lighting or even manually.
Methods
A die shot is a picture of a computer chip without its housing or packaging. There are two ways to capture such a chip "naked" on a photo; by either taking the photo before a chip is packaged or by removing its package.
Avoiding the package
Taking a photo before the chip ends up in a housing is typically preserved to the chip manufacturer, because the chip is packed fairly quickly in the production process to protect the sensitive very small parts against external influences. However, manufacturers may be reluctant to share die shots to prevent competitors from easily gaining insight into the technological progress and complexity of a chip.
Removing the package
Removing the housing from a chip is typically a chemical process called decapping - a chip is so small and the parts are so microscopic that opening a housing (also named delidding) with tools such as saws, sanders or dremels could damage the chip in such a way that a die shot is no longer or less useful. For example, sulphuric acid can be used to dissolve the plastic housing of a chip. Chips are immersed in a glass jar with sulphuric acid, after which the sulphuric acid is boiled for up to 45 minutes at a temperature of 337 degrees Celsius. Once the plastic housing has decayed, there may be other processes to remove leftover carbon, such as with a hot bath of concentrated nitric acid. After this, the contents of a chip are relatively exposed and a picture can be made of the chip with macrophotography or microphotography.
Legal aspects
The circuit layout of integrated circuits is generally not subject to copyright, because it is functional in nature. Since die shots are usually much too low in resolution and picture many layers at once, it is impossible to reproduce the pictured circuits using a die shot. Therefore die shots are not restricted under laws like the Semiconductor Chip Protection Act of 1984.
Gallery
See also
Die (integrated circuit)
References
External links
"Hardwarecop CPU Museum" - a website showing die shots sorted per ship-series.
CPU Graveyard dieshots - wiki with over 1000 die shots.
YouTube-video explaining how one can take a die shot.
Integrated circuits
Photography | Die shot | [
"Technology",
"Engineering"
] | 550 | [
"Computer engineering",
"Integrated circuits"
] |
70,180,977 | https://en.wikipedia.org/wiki/Verticordia%20elizabethiae | Verticordia elizabethiae, named as Elizabeth's featherflower, is a flowering plant in the myrtle family, Myrtaceae. An endemic species of Southwest Australia, it occurs near salt lakes as an erect bushy shrub.
Taxonomy
A species of Verticordia, the featherflowers, assigned to a section of the genus Verticordia sect. Verticordella. The type was collected in 2018 at a location reported imprecisely as Baladjie. Previously collected specimens, including one made by Charles Gardner in 1926 and another recognised as Verticordia sp. Koolyanobbing, were assigned by the authors, Barbara Rye and Matthew Barrett, to the new species.
The specific epithet honours the extensive contribution of Elizabeth Anne (Berndt) George, née Sykes (1935-2012) to the collection and research of verticordias. A treatment of the population had previously been published by George as an inland variant of Verticordia halophila.
Description
A low growing salt tolerant shrub between 0.4 and 1.2 metres in width and 0.3 to 0.6 m high. The species lacks evidence of a lignotuber.
Distribution and habitat
Only known at a restricted distribution range within the semi-arid Coolgardie bioregion, in an area near Southern Cross, Western Australia. It occurs on flats around salt lakes amongst other halophytes forming heath communities, species of Maireana, Gunniopsis and Frankenia, associated with Callitris.
References
elizabethiae
Halophytes
Endemic flora of Western Australia
Rosids of Western Australia
Plants described in 2020 | Verticordia elizabethiae | [
"Chemistry"
] | 332 | [
"Halophytes",
"Salts"
] |
70,181,938 | https://en.wikipedia.org/wiki/Postman%20%28software%29 | Postman is an Indian-origin global software company that offers an API platform for developers to design, build, test, and collaborate on APIs. Over 30 million registered users and 500,000 organizations are using Postman. Postman also maintains the Postman API Network, a directory of over 100,000 public APIs that is listed as the world’s largest such collection. The company is headquartered in San Francisco and maintains additional offices in Tokyo and Bangalore, where Postman was founded.
History
Postman started in 2012 as a side project of software engineer Abhinav Asthana, who wanted to simplify API testing while working at Yahoo Bangalore. He named his app Postman – a play on the API request “POST” – and offered it free in the Chrome Web Store. As the app's usage grew to 500,000 users with no marketing, Abhinav recruited former colleagues Ankit Sobti and Abhijit Kane to help create Postman, Inc. The three co-founders lead the company today, with Abhinav serving as CEO and Ankit as CTO.
In 2023, Postman announced it had acquired Akita, an API observability solution. In 2024, Postman acquired Orbit, a solution for building and managing developer communities.
Features
Postman features include:
Workspaces: Personal, team, partner, and public workspaces allow for API collaboration internally and externally
API repository: Allows users to store, catalog, and collaborate around API artifacts in a central platform within public, private, or partner networks
API builder: Helps implement an API design workflow through specifications including OpenAPI, GraphQL, and RAML. Integrates varied source controls, CI/CD, gateways, and APM solutions
Tools: API client, API design, API documentation, API testing, mock servers, and API detection
Intelligence: Security warnings, API repository search, workspaces, reporting, API governance
Postman v11 was released in May 2024. The update includes AI-powered features to help developers with API test generation, documentation, debugging, and data visualization. V11 also enables more users to share API collections with external partners.
Business model
Postman offers tiered pricing, ranging from free options for small teams to paid plans for larger companies and enterprises.
Ownership
Postman is privately held, with funding from Nexus Venture Partners, CRV, Insight Partners, Coatue, Battery Ventures, and Mary Meeker’s BOND. In May 2015, the company raised a $1 million seed round. In August 2021, Postman raised a $225 million Series D round at a $5.6 billion valuation.
References
Software testing
Automation software
Application programming interfaces | Postman (software) | [
"Engineering"
] | 552 | [
"Software engineering",
"Automation software",
"Software testing",
"Automation"
] |
70,182,860 | https://en.wikipedia.org/wiki/11%20Sagittae | 11 Sagittae is a blue in the constellation Sagitta with a spectral type of B9III.
Naming
It is in the Chinese asterism (), or Left Flag which consists of 11 Sagittae, γ Sagittae, α Sagittae, β Sagittae, δ Sagittae, ζ Sagittae, 13 Sagittae, 14 Sagittae and ρ Aquilae. Consequently, the Chinese name for γ Sagittae itself is (, ).
References
B-type giants
Sagitta
Sagittae, 11
189090
7622
098324 | 11 Sagittae | [
"Astronomy"
] | 135 | [
"Sagitta",
"Constellations"
] |
70,182,917 | https://en.wikipedia.org/wiki/Robert%20Otto%20Pohl | Robert Otto Pohl (December 17, 1929 – August 30, 2024) was a German-American physicist, specializing in condensed matter physics topics such as solid state physics, thermal conductivity, and thin films, who was the Goldwin Smith Emeritus Professor of Physics at Cornell University where he has been on the faculty since the 1950s.
Life and career
Robert O. Pohl's father was the physicist Robert Wichard Pohl (1884–1976), whose maternal grandfather was Friedrich Wichard Lange (1826–1884), a member of the Hamburg Parliament. After completing undergraduate study at the University of Freiburg, Robert O. Pohl matriculated as a graduate student at the University of Erlangen. There he graduated with a Diplom (M.S.) in 1955 and a doctorate in 1957 and worked as an assistant in physics for the academic year 1957–1958. He emigrated to the United States in 1958.
At Cornell University he was a research associate (from 1958 to 1960), an assistant professor from 1960 to 1963, an associate professor from 1963 to 1968), a full professor from 1968 to 2000, and Goldwin Smith Emeritus Professor of Physics from 2000 to 2024. He held visiting appointments at RWTH Aachen University (1964), the University of Stuttgart (1966–1967), the Ludwig Maximilian University of Munich, the University of Konstanz, the University of Regensburg, New Zealand's University of Canterbury, China's Tongji University, and the Nuclear Research Center in Jülich.
Robert O. Pohl has done research on experimental investigations of glass and glassy materials, as well as heat transport and lattice transport behavior in crystalline solids and in amorphous solids, structure of glass, cryogenic techniques, and energy problems.
In 1985 he received the Oliver E. Buckley Condensed Matter Prize for "his pioneering work on low energy excitations in amorphous materials and continued important contributions to the understanding of thermal transport in solids." It was considered the highest recognition in condensed matter physics.
Pohl was elected in 1972 a fellow of the American Physical Society, in 1984 a fellow of American Association for the Advancement of Science and in 1999 a member of the National Academy of Sciences. For the academic year 1973–1974 he was a Guggenheim Fellow. In 1980 he received the Humboldt US Senior Scientist Award.
His doctoral students included Venkatesh Narayanamurti.
Springer published Robert Wichard Pohl's 3-volume edition of Einführung in die Physik (vol. 1, Mechanik und Akustik, 1930; vol. 2, Elektrizitätslehre, 1927; vol. 3, 1940, Optik) with many later editions and a 2-volume edition edited by Klaus Lüders and Robert O. Pohl (vol. 1, Mechanik, Akustik und Wärmelehre, 19th edition, 2004; vol. 2, 22nd edition, 2006). Robert O. Pohl added videos of demonstration experiments for the latest editions.
Pohl died in Göttingen, Germany on August 30, 2024, at the age of 94.
Pohl's opinions on nuclear waste disposal
In addition to his main research interests, Robert O. Pohl was concerned about radioactive waste disposal and its effects on the environment and human health. During the Carter administration he served on a Presidential advisory committee on nuclear waste disposal.
In a 1982 article published in Physics Today, Pohl wrote:
See also
Nuclear Waste Policy Act
Ocean disposal of radioactive waste
Selected publications
Articles
(over 500 citations)
(over 2200 citations)
(over 1050 citations) See aluminium nitride.
(over 400 citations)
(over 450 citations)
(over 3050 citations)
(over 2000 citations)
(over 400 citations)
Books
translated from Pohls Einführung in die Physik, Band. 1 : Mechanik, Akustik und Wärmelehre by William D. Brewers (Vol. 1 contains 77 videos of experiments.)
translated from Pohls Einführung in die Physik, Band.2 : Elektizitaetslehre und Optik by William D. Brewer (Vol. 2 contains 41 videos of experiments.)
References
External links
(movie from the early 1970s)
(creators: Klaus Lüders, Robert Otto Pohl, et al.)
(creators: Klaus Lüders, Robert Otto Pohl, et al.)
1929 births
2024 deaths
20th-century German physicists
21st-century German physicists
20th-century American physicists
21st-century American physicists
Condensed matter physicists
University of Freiburg alumni
University of Erlangen-Nuremberg alumni
Cornell University faculty
Fellows of the American Physical Society
Fellows of the American Association for the Advancement of Science
Members of the United States National Academy of Sciences
Oliver E. Buckley Condensed Matter Prize winners | Robert Otto Pohl | [
"Physics",
"Materials_science"
] | 987 | [
"Condensed matter physicists",
"Condensed matter physics"
] |
70,183,473 | https://en.wikipedia.org/wiki/Past%20hypothesis | In cosmology, the past hypothesis is a fundamental law of physics that postulates that the universe started in a low-entropy state, in accordance with the second law of thermodynamics. The second law states that any closed system follows the arrow of time, meaning its entropy never decreases. Applying this idea to the entire universe, the hypothesis argues that the universe must have started from a special event with less entropy than is currently observed, in order to preserve the arrow of time globally.
This idea has been discussed since the development of statistical mechanics, but the term "past hypothesis" was coined by philosopher David Albert in 2000. Philosophical and theoretical efforts focus on trying to explain the consistency and the origin of the postulate.
The past hypothesis is an exception to the principle of indifference, according to which every possible microstate within a certain macrostate would have an equal probability. The past hypothesis allows only those microstates that are compatible with a much-lower-entropy past, although these states are assigned equal probabilities. If the principle of indifference is applied without taking into account the past hypothesis, a low- or medium-entropy state would have likely evolved both from and toward higher-entropy macrostates, as there are more ways statistically to be high-entropy than low-entropy. The low- or medium-entropy state would have appeared as a "statistical fluctuation" amid a higher-entropy past and a higher-entropy future.
Common theoretical frameworks have been developed in order to explain the origin of the past hypothesis based on inflationary models or the anthropic principle. The Weyl curvature hypothesis, an alternative model by Roger Penrose, argues a link between entropy, the arrow of time and the curvature of spacetime (encoded in the Weyl tensor).
See also
Loschmidt's paradox
Entropy as an arrow of time
Notes
References
Philosophy of thermal and statistical physics
Philosophy of time | Past hypothesis | [
"Physics",
"Chemistry"
] | 394 | [
"Philosophy of thermal and statistical physics",
"Physical quantities",
"Time",
"Philosophy of time",
"Thermodynamics",
"Spacetime",
"Statistical mechanics"
] |
70,183,840 | https://en.wikipedia.org/wiki/Naoki%20Saito%20%28mathematician%29 | Naoki Saito is an applied mathematician specializing in applied and computational harmonic analysis, and interested in feature extraction, pattern recognition, graph signal processing, statistical signal processing, Laplacian eigenfunctions, and human and machine perception.
Education
Saito studied at the University of Tokyo, receiving his BEng in 1982 and his MEng in 1984. He joined Nippon Schlumberger K.K. in 1984, and in 1986 moved to Schlumberger-Doll Research (SDR), Ridgefield, Connecticut, where he was a research scientist. He continued his studies, receiving his PhD in applied mathematics from Yale University in 1994.
Career
Saito began teaching at the Department of Mathematics at the University of California, Davis in 1997, where he is currently a professor and a director of the UC Davis TETRAPODS Institute of Data Science, one of National Science Foundation's Transdisciplinary Research In Principles Of Data Science (TRIPODS) Institutes, which brings together the theoretical computer science, electrical engineering, mathematics, and statistics communities to develop the theoretical foundations of data science. He was also Chair of the Graduate Group in Applied Mathematics at UC Davis from 2007 to 2012. He is a senior member of IEEE as well as a member of IMS, SIAM, and JSIAM.
He served as Chair of the SIAM Activity Group on Imaging Science from 2013 to 2015, and is a member of the editorial board of Applied and Computational Harmonic Analysis, Inverse Problems and Imaging, and Journal of Mathematical Imaging and Vision.
Saito received the Best Paper Awards from the SPIE (1994), and JSIAM (2016) as well as the Henri Doll Award from Schlumberger (1997), Young Investigator Award from the ONR (2000), and the Presidential Early Career Award for Scientists and Engineers (PECASE) (2000).
Saito has contributed to a number of notable interdisciplinary projects including the development of a noninvasive fetal oxygen monitor as well as the Lake Tahoe Sonification Project in 2014.
References
External links
Naoki Saito, at University of California, Davis
Japanese mathematicians
Year of birth missing (living people)
Living people
University of Tokyo alumni
Yale Graduate School of Arts and Sciences alumni
Applied mathematicians
University of California, Davis faculty
Senior members of the IEEE
Recipients of the Presidential Early Career Award for Scientists and Engineers | Naoki Saito (mathematician) | [
"Mathematics"
] | 474 | [
"Applied mathematics",
"Applied mathematicians"
] |
70,187,145 | https://en.wikipedia.org/wiki/Importance%20Value%20Index | The Importance Value Index in Ecology is the measure of how dominant a species is in a given ecosystem.
References
Indexes
Ecology
Biodiversity | Importance Value Index | [
"Biology"
] | 27 | [
"Ecology",
"Biodiversity"
] |
57,749,328 | https://en.wikipedia.org/wiki/Trans-Dichlorobis%28ethylenediamine%29cobalt%28III%29%20chloride | trans-Dichlorobis(ethylenediamine)cobalt(III) chloride is a salt with the formula [CoCl2(en)2]Cl (en = ethylenediamine). It is a green diamagnetic solid that is soluble in water. It is the monochloride salt of the cationic coordination complex [CoCl2(en)2]+. One chloride ion in this salt readily undergoes ion exchange but the two other chlorides are less reactive, being bound to the metal center. The more stable cis-dichlorobis(ethylenediamine)cobalt(III) chloride is also known.
Synthesis
The compound is synthesized by the reaction of cobalt(II) chloride and ethylenediamine in hydrochloric acid in the presence of oxygen:
4 CoCl2 + 8 en + 4 HCl + O2 → 4 trans-[CoCl2(en)2]Cl + 2 H2O
The initial product contains HCl, which is removed by heating. Alternatively, (carbonato)bis(ethylenediamine)cobalt(III) chloride reacts with hydrochloric acid at 10 °C to give the same species.
[Co(CO3)(en)2]Cl + 2 HCl → trans-[CoCl2(en)2]Cl + CO2 + H2O
Related complexes
This salt is more soluble than cis-dichlorobis(ethylenediamine)cobalt(III) chloride. This pair of isomers were significant in the development of the area of coordination chemistry. The chiral cis isomer is obtained by heating the trans isomer. Both isomers of dichlorobis(ethylenediamine)cobalt(III) have often been used in stereochemical studies. The trans isomer cation has idealized D2h point group symmetry, whereas the cis isomer cation has C2 symmetry.
Tris(ethylenediamine)cobalt(III) chloride in contrast to the bis(ethylenediamine) complexes does not undergo substitution.
References
Chlorides
Chloro complexes
Cobalt complexes
Cobalt(III) compounds
Ethylenediamine complexes | Trans-Dichlorobis(ethylenediamine)cobalt(III) chloride | [
"Chemistry"
] | 458 | [
"Chlorides",
"Inorganic compounds",
"Salts"
] |
57,750,049 | https://en.wikipedia.org/wiki/Induction-induction | In intuitionistic type theory (ITT), a discipline within mathematical logic, induction-induction is for simultaneously declaring some inductive type and some inductive predicate over this type.
An inductive definition is given by rules for generating elements of some type. One can then define some predicate on that type by providing constructors for forming the elements of the predicate, such inductively on the way the elements of the type are generated. Induction-induction generalizes this situation since one can simultaneously define the type and the predicate, because the rules for generating elements of the type are allowed to refer to the predicate .
Induction-induction can be used to define larger types including various universe constructions in type theory. and limit constructions in category/topos theory.
Example 1
Present the type as having the following constructors, note the early reference to the predicate :
and-simultaneously present the predicate as having the following constructors :
if and then
if and and then .
Example 2
A simple common example is the Universe à la Tarski type former. It creates some inductive type and some inductive predicate . For every type in the type theory (except itself!), there will be some element of which may be seen as some code for this corresponding type; The predicate inductively encodes each possible type to the corresponding element of ; and constructing new codes in will require referring to the decoding-as-type of earlier codes, via the predicate .
See also
Induction-recursion – for simultaneously declaring some inductive type and some recursive function on this type .
References
External links
A list of Peter Dybjer's publications on induction and induction-recursion
Type theory | Induction-induction | [
"Mathematics"
] | 357 | [
"Type theory",
"Mathematical logic",
"Mathematical structures",
"Mathematical objects"
] |
57,751,953 | https://en.wikipedia.org/wiki/Active%20Student%20Response%20Techniques | Active student response (ASR) techniques are strategies to elicit observable responses from students in a classroom. They are grounded in the field of behavioralism and operate by increasing opportunities reinforcement during class time, typically in the form of instructor praise. Active student response techniques are designed so that student behavior, such as responding aloud to a question, is quickly followed by reinforcement if correct. Common form of active student response techniques are choral responding, response cards, guided notes, and clickers. While they are commonly used for disabled populations, these strategies can be applied at many different levels of education. Implementing active student response techniques has been shown to increase learning, but may require extra supplies or preparation by the instructor.
History
Active student response techniques are grounded in the field of behaviorism, a movement in psychology that believes behaviors are responses to stimuli and motivated by past reinforcement. The field has its origins in experiments of Edward Thorndike, who pioneered the Law of effect, which is now known as reinforcement and punishment. Thorndike explained that behaviors that produce a positive effect become more likely to reoccur, given the same scenario. Conversely, behaviors that produce a negative effect become less likely to reoccur.
Psychologist B.F. Skinner applied the principles of behaviorism to influence education. Skinner believed that students must be active in the classroom and that effective instruction is based on positive reinforcement. According to Skinner, teachers should avoid punishment, as it only teaches students to avoid punishment. Instead, lessons should be broken into small tasks with clear instruction and positive reinforcement. His beliefs led him to invent the teaching machine. Active student response techniques use Skinner's model to provide rapid reinforcement for desired responses. This increases the likelihood the responses will occur again. Also, these techniques may give instructors an opportunity to embrace technology in the classroom.
The foundation of active student response techniques is behaviorism's stimulus-response-reinforcement paradigm. A stimulus is any environmental change that may produce a response. In an academic setting, a stimulus is often a verbal cue. The response may be any change by the subject, such as an emotion or a behavior. Reinforcers are either positive or negative. In an academic setting, confirmation of a correct answer may be a positive reinforcer. So, active student response techniques aim to arrange the paradigm so the response is most correct. This includes separating instruction into small, achievable steps, providing clear and quick feedback, and including many repetitions. As a result, the correct response will have a strong relationship to the stimulus, creating more learning.
Methods
Choral responding
Choral responding is a low-tech, high-ASR strategy that paces instruction throughout a class. In this strategy, students are prompted to respond orally in unison to questions posed by an instructor. For choral responding to work, questions must be presented clearly, be able to answered briefly, and have one correct answer. Choral responding is useful for reviewing subject matter, solving problems, or spelling words. It may be used to review previously covered content or provide feedback throughout a class period. Choral responding is effective in both small- and whole-group instruction, for students from preschool through secondary grades, in both general education and special education, as measured by learning outcomes.
The instructional format for choral responding is the following:
Instructor poses a question (e.g. "What is 9x9?")
Appropriate wait-time pause
Instructor uses a clear signal (e.g. "Tell me.")
Instructor provides feedback for the majority answer (e.g. Correct! 9x9 is 81.")
Response cards
Response cards are cards, signs, or other objects held up by students in unison in response to a question posed by an instructor. Write-on response cards, such as whiteboards, allow students to write their answers on the spot and erase between learning trials. Pre-printed response cards are pre-made and are often true/false or colors to indicate answers. Both types of response cards promote high-ASR by allowing all students to respond to all questions, instead of one student responding to each. Instructors can easily gauge learning using response cards.
The instructional format of response cards is similar to choral responding, as follows:
Instructor poses a question with a clear, quick response (e.g. "What is the atomic number of carbon?")
Appropriate wait-time pause for students to write answers
Instructor uses a clear signal (e.g. "Show me your boards!")
Instructor provides feedback (e.g. "That's right! The atomic number of carbon is 6.) Occasionally, the instructor may want to address some of the incorrect responses that were given.
Implementing response cards in a classroom may increase questions posed by the instructor, increase academic performance, and be favored by students. The technique is effective in both general education and special education. Response cards may also increase on-task behavior in the classroom and decrease disruptive behavior. Response cards are most effective when paired with brisk instructional pacing. Instructors have been easily able to implement response cards and achieve a response rate of approximately one response per minute. The brisk instructional pace maximized responses in a class period without sacrificing accuracy and while minimizing problem behavior.
Guided notes
Notetaking serves both a process and product function. But, traditional notetaking is dependent on attendance, criterion knowledge, and attention. Often, students may be inefficient note takers by recording incomplete, verbatim notes. Distributing instructor's notes increases academic performance. Guided notes aims to improve notetaking behavior by ensuring complete and accurate notes.
Guided notes are prepared handouts containing standard cues to guide a student through a lecture. The handouts are often based on the instructor's notes with blank spaces throughout for the student to fill in. In the blank spaces, the student is to complete the information or concept, creating a high-ASR strategy with many response opportunities throughout the lecture. The blank spaces should be varied and may allow for many different types of responses, such as drawing pictures or graphs. While mostly low-tech, guided notes has the option to use many high-tech applications, such as software that makes guided notes from completed notes. Guided notes are used in both K-12 level and college levels. The active student response technique improves assessment scores, accuracy of notes, and student responses during lecture. Most students prefer guided notes over traditional notetaking.
The instructional format of guided notes is as follows:
Instructor makes an outline of the lecture, and should contain clear typographical cues, such as bullet points
Instructor replaces some sections with blank spaces where the student will write in the information
Guided notes are distributed to students for the lecture
Example of guided notes:
The space between two neurons is the _. Neurons most often exhibit ___ signaling within cells and ___ signaling between cells. The generation of the ___ potential produces an __-or-none response. So, greater intensity stimulation produces higher .
High-tech strategies
Response strategies can be implemented using commercially available technologies, such as clickers or mobile phone apps. Similar to response cards, the instructor would pose a question and ask for a response from the class. Some of the process may be automated with a software that uses a clear signal for response and collects student responses. Though, high-tech strategies are not as well researched.
Applications
Active student response techniques can be applied to nearly all levels of education. Also, the techniques can be used with multiple populations. The Individuals with Disabilities Education Act (IDEA) prioritizes accessible general education that includes individuals with disabilities, including those with autism spectrum disorder, intellectual disabilities, learning disabilities, and behavior disorders. Active student response benefits the inclusion of students with disabilities in classrooms by facilitating all students' participation in the classroom.
Higher education may also benefit from active student response techniques.. Undergraduate classrooms would often benefit from implementing the techniques. While traditional lectures serve a function in higher education, such as setting context and synthesizing information, the reliance on passive learning is not as effective as active student learning.
Active student response strategies can be either low- or high-tech. High-tech strategies, which use electrical devices, may utilize mobile phones, clickers, or other devices. Low-tech strategies do not require any electrical devices and may not require anything more than pencil and paper. Examples include guided notes and response cards. The range of technology that can be used broadens the applications of active student response.
Compared to traditional teaching styles
Traditional lecturing, in which an instructor speaks uninterrupted for the majority of the class, is often less effective than active student response techniques. Without active participation from students and contingent positive reinforcement for correct responses, traditional lecturing does not reinforce desired behaviors. Traditional lecturing may allow disorganized delivery of information. Implementing active student response techniques into lectures ensures the lectures function to assess, instruct, plan, and evaluate.
Active student response techniques have been shown to increase learning, compared to traditional lecture. During lectures with active student response, students exhibited more on-task behavior, and instructors received more feedback. Frequency of active student responses is correlated with performance on evaluations. Instructors also remarked that active student participation provides instructors with clear feedback and promotes a more inclusive nature of the classroom.
However, active student response also demands a higher cost. Instructors must supply or prepare any necessary materials. For example, to implement guided notes, instructors must write and print the notes to distribute to students. Similarly, the techniques demand more time from instructors. It may take added preparation to plan all of the questions throughout class. If an instructor chooses to use response cards, the instructor must prepare questions to which the class can respond.
References
Behaviorism
Educational practices | Active Student Response Techniques | [
"Biology"
] | 1,970 | [
"Behavior",
"Behaviorism"
] |
57,752,176 | https://en.wikipedia.org/wiki/21-Crown-7 | 21-Crown-7 is an organic compound with the formula [C2H4O]7 and the IUPAC name 1,4,7,10,13,16,19-heptaoxacycloheneicosane. Similar to other crown ethers, 21-crown-7 functions as a ligand for certain metal cations, with a specific affinity for caesium cations. The dipole moment of 21-crown-7 varies depending on the solvent and temperatures.
References
External links
ChemicalBook
Crown ethers
Macrocycles | 21-Crown-7 | [
"Chemistry"
] | 114 | [
"Organic compounds",
"Crown ethers",
"Macrocycles"
] |
57,752,446 | https://en.wikipedia.org/wiki/Estradiol%203-saccharinylmethyl%20ether | Estradiol 3-saccharinylmethyl ether (E2SME), also known as 3-O-(saccharinylmethyl)-17β-estradiol, is a synthetic estrogen and estrogen ether – specifically, the C3 saccharinylmethyl ether of estradiol – which was described in the mid-1990s and was never marketed. It is a prodrug of estradiol and appears to be partially protected from first-pass metabolism in the liver and intestines with oral administration, showing greatly improved oral potency compared to estradiol.
E2SME has been found to be 9-fold as potent as estradiol by the oral route in rats. Similarly, its bioavailability (16%) was 5-fold greater than that of estradiol via the oral route in rats, and the elimination half-life of released estradiol was 5- to 7-fold longer than that of regular estradiol. Conversely, when E2SME and estradiol were given intravenously in rats, there was no difference between them in terms of potency. In vitro studies revealed that E2SME is not hydrolyzed to estradiol enzymatically but rather is hydrolyzed chemically in biological media such as plasma, apparently dependent on the concentration of protein.
See also
List of estrogen esters § Ethers of steroidal estrogens
References
Abandoned drugs
Benzoisothiazolinones
Secondary alcohols
Estrogen ethers
Estradiol esters
Sulfonamides
Synthetic estrogens | Estradiol 3-saccharinylmethyl ether | [
"Chemistry"
] | 333 | [
"Drug safety",
"Abandoned drugs"
] |
57,752,945 | https://en.wikipedia.org/wiki/Estradiol%20acetylsalicylate | Estradiol acetylsalicylate, or estradiol 3-acetylsalicylate, is a synthetic estrogen and estrogen ester – specifically, the C3 acetylsalicylic acid (aspirin) ester of estradiol – which was described in the late 1980s and was never marketed. In dogs, the oral bioavailability of estradiol acetylsalicylate was found to be 17-fold higher than that of unmodified estradiol. However, a subsequent study found that the oral bioavailability of estradiol and estradiol acetylsalicylate did not differ significantly in rats (4.3% and 4.2%, respectively), suggestive of a major species difference.
See also
List of estrogen esters § Estradiol esters
References
Abandoned drugs
Estradiol esters
Acetylsalicylic acids
Salicylate esters | Estradiol acetylsalicylate | [
"Chemistry"
] | 200 | [
"Drug safety",
"Abandoned drugs"
] |
57,753,079 | https://en.wikipedia.org/wiki/Estradiol%20salicylate | Estradiol salicylate, or estradiol 3-salicylate, is a synthetic estrogen and estrogen ester – specifically, the C3 salicylic acid ester of estradiol – which was described in the late 1980s and was never marketed. It is a metabolite of estradiol acetylsalicylate, which appears to be very rapidly hydrolyzed into estradiol salicylate.
See also
List of estrogen esters § Estradiol esters
References
Abandoned drugs
Estradiol esters
Salicylic acids | Estradiol salicylate | [
"Chemistry"
] | 123 | [
"Drug safety",
"Abandoned drugs"
] |
57,753,096 | https://en.wikipedia.org/wiki/Estradiol%20anthranilate | Estradiol anthranilate, or estradiol 3-anthranilate, is a synthetic estrogen and estrogen ester – specifically, the C3 anthranilic acid ester of estradiol – which was described in the late 1980s and was never marketed. In dogs, the oral bioavailability of estradiol anthranilate was found to be 5-fold higher than that of unmodified estradiol. However, a subsequent study found that the oral bioavailability of estradiol and estradiol anthranilate did not differ considerably in rats (4.3% and 3.2%, respectively), suggestive of a major species difference.
See also
List of estrogen esters § Estradiol esters
References
Abandoned drugs
Anthranilic acids
Estradiol esters | Estradiol anthranilate | [
"Chemistry"
] | 177 | [
"Drug safety",
"Abandoned drugs"
] |
57,753,344 | https://en.wikipedia.org/wiki/Estradiol%20benzoate%20cyclooctenyl%20ether | Estradiol benzoate cyclooctenyl ether (EBCO), or estradiol 3-benzoate 17β-cyclooctenyl ether, is a synthetic estrogen as well as estrogen ester and ether – specifically, the C3 benzoate ester and C17β cyclooctenyl ether of estradiol – which was described in the early 1970s and was never marketed. It has been found to have a dramatically prolonged duration of action with oral administration in animals, similarly to the related compound quinestrol (the 3-cyclopentyl ether of ethinylestradiol). A single oral dose of EBCO sustained high uterus weights for 3 weeks in rats. This long-lasting activity may be due to storage of EBCO in fat. It appears that EBCO is absorbed satisfactorily from the gastrointestinal tract, at least partially survives first-pass metabolism in the liver and intestines, and is then sequestered into fat, from which it is slowly released and activated into estradiol. In contrast to quinestrol, the oral activity of EBCO is greatly improved when it is delivered in an oil solution as opposed to an aqueous vehicle.
See also
List of estrogen esters § Ethers of steroidal estrogens
References
Abandoned drugs
Benzoate esters
Estradiol esters
Estrogen ethers
Synthetic estrogens | Estradiol benzoate cyclooctenyl ether | [
"Chemistry"
] | 309 | [
"Drug safety",
"Abandoned drugs"
] |
57,754,885 | https://en.wikipedia.org/wiki/Mineral%20waters%20of%20Nakhchivan | Mineral waters of Nakhchivan are water springs in Nakhchivan Autonomous Republic that contain various minerals such as, sodium, potassium, magnesium, chloride and sulfur compounds.
Overview
There are approximately seven thousand artesian aquifers and more than two hundred mineral water springs in Nakhchivan. Mineral water springs of Nakhchivan cover about 60% of overall water sources of Azerbaijan. Sirab, Badamli, Vaykhir, Gulustan and Daridagh are considered as the most popular water sources in Nakhchivan. They are used as a treatment and potable water sources. Research works of the mineral waters in this territory were started in the 1840s and centralized exploration works carried out there in the twentieth century. According to the investigations, there are six types, sixteen categories and thirty-three spices of mineral waters in Nakhchivan and 98% of them contain Carbon dioxide. The majority of mineral waters’ temperature is 8 °C - 22 °C. There are explored waters with 50 °C and more in Sirab and Daridagh springs. 35% of Carbon dioxide abundant mineral waters of the country are situated in Nakhchivan Autonomous Republic.
Mineral water springs in Nakhchivan
Sirab
Sirab mineral water spring located in Babek district (18 kilometers north – east of Nakhchivan city) and it is 1100-meter-high from sea level in Sirab village. The origin of the word “sirab” consists of two parts “sir” and “ab” means “secret water”. There are differentiated three types of water in this spring regarding to their compositions.
The first type is Carbon Dioxide, Hydro carbonate, sodium – potassium abundant and less mineralized. Regarding to the chemical composition, it is close to the water of Kislovodsk.
The second one is Carbon Dioxide, Hydro Carbonate, potassium abundant and medium mineralized. It is similar to the Borjomi (Georgia).
The third type is highly mineralized and consists of Carbon Dioxide, Arsenic, Hydro carbonate – chloride, potassium. It is related to the waters of Sinegorsk (Sakhalin) and Daridagh (Julfa).
Sirab mineral water is used as a treatment for diseases such as, liver and gastroenterostomy oriented. This mineral water exported to the countries such as, Russia, China, Turkey, Belarus, Kazakhstan, Turkmenistan, Iran, Iraq, Poland, Ukraine, Qatar, and Baltic states from Azerbaijan.
Badamli
Source of the Badamli mineral water is located 1274 meters high from the sea level in Shahbuz district (three kilometers south – west of the Badamli village) and consists of the several springs. The chemical composition of the water consists of minerals such as, Carbon Dioxide, Hydro carbonate – chloride and sodium – potassium. Badamli is Narzan (Kislovodsk) and Saqveri (Georgia) typed healing – beverage water.
Daridagh
Daridagh mineral water located in Culfa district and consists of five springs and 32 exploration wells. The source of the water is 800–900 meters high from the sea level. According to the chemical composition Daridagh mineral water is arsenic and highly mineralized chloride – hydro carbonate – sodium abundant, and close to the Kudova (Poland), La – Burbula (France), Durkheim (Germany) and Sinegorsk (Russia) mineral waters.
Vaykhir
Mineral water Vaykhir is located 1100 meters high from the sea level in Babek district. Vaykhir mineral water consists of a number of springs and two types of waters were found from the central well.
Yessentuki typed medium mineralized, Carbon dioxide, hydro carbonate – chloride and sodium – potassium abundant water.
Sirab and Soymi typed low mineralized, Carbon dioxide and hydro carbonate – potassium – sodium.
Vaykhir mineral water is beneficial for the treatment of diseases such as, hepatitis, inflammation of gallbladder, chronic gastritis and chronic colitis.
Gulustan
Gulustan mineral water is Sirab and Kislovodsk typed and located in Culfa district. The well was dug in 1962 and is more than 130 meters deep. Chemical composition consists of magnesium, sodium, potassium, carbonate and carbon dioxide and mostly used as a treatment for gastroenterostomy diseases.
Batabat
Batabat mineral water is located 1700 high from the sea level in the north – east of the Nakhchivan city. Magnesium, hydro carbonated, sodium – potassium abundant water is beneficial for gastroentric diseases.
References
Mineral water | Mineral waters of Nakhchivan | [
"Chemistry"
] | 941 | [
"Mineral water"
] |
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 | [
"Galaxies",
"Astronomical objects"
] |
57,756,777 | https://en.wikipedia.org/wiki/R13%20%28drug%29 | R13 is a small-molecule flavonoid and orally active, potent, and selective agonist of the tropomyosin receptor kinase B (TrkB) – the main signaling receptor for the neurotrophin brain-derived neurotrophic factor (BDNF) – which is under development for the potential treatment of Alzheimer's disease. It is a structural modification and prodrug of tropoflavin (7,8-DHF) with improved potency and pharmacokinetics, namely oral bioavailability and duration. The compound is a replacement for the earlier tropoflavin prodrug R7 and has similar properties to it. It was developed because while R7 displayed a good drug profile in animal studies, it showed almost no conversion into tropoflavin in human liver microsomes. In contrast to R7, R13 is readily hydrolyzed into tropoflavin in human liver microsomes.
See also
List of investigational antidepressants
Tropomyosin receptor kinase B § Agonists
References
External links
7,8-Dihydoxyflavone and 7,8-substituted flavone derivatives, compositions, and methods related thereto (US9975868B2)
Antidementia agents
Carbamates
Esters
Experimental drugs
Flavones
Neuroprotective agents
Nootropics
Prodrugs
TrkB agonists | R13 (drug) | [
"Chemistry"
] | 308 | [
"Esters",
"Functional groups",
"Prodrugs",
"Organic compounds",
"Chemicals in medicine"
] |
57,757,047 | https://en.wikipedia.org/wiki/IGTV | IGTV, short for Instagram TV, was a video application by Instagram for Android and iOS smartphones. It allowed for longer videos compared to Instagram feeds. IGTV was available as a stand-alone app, though basic functionality was also available within the Instagram app and website.
The service was launched and introduced by former Instagram CEO Kevin Systrom in a live event in San Francisco on June 20, 2018, featuring creators such as Lele Pons.
Service
IGTV required users to log in with an Instagram account. Mobile devices allowed uploads of up to 15 minutes in length with a file size of up to 650 MB, while desktop web browsers allowed uploads of up to 60 minutes in length with a file size of up to 3.6 GB. The app auto-played videos as soon as it was launched, which Kevin Systrom contrasted to video hosts where one must first locate a video.
Instagram accounts with an IGTV channel received an IGTV tab on their profile page. Additionally, uploads on IGTV could be mirrored to a linked Facebook page.
In May 2019, IGTV gained the ability to upload landscape videos.
The standalone app was not widely adopted; in January 2020, it was reported that it only had around 7 million users. In October 2021, Instagram began to merge IGTV's functionality into the main Instagram app, including its video upload and editing functionality, changing the IGTV tab on user profiles to simply "Video"—which included IGTV posts and existing in-feed videos and live streams (though excluding Reels, its short-form video format), and updating the video playback interface. Instagram stated that the standalone app would remain operational for the time being.
In February 2022, Instagram announced that IGTV would be discontinued in March 2022, electing to focus on video functionality in the main app (including Reels).
References
External links
2018 software
2018 introductions
2018 establishments in California
IOS software
Mobile software
Proprietary cross-platform software
Social software
Video software
Instagram
Vertical video | IGTV | [
"Technology"
] | 435 | [
"Mobile software stubs",
"Mobile content",
"Mobile technology stubs",
"Social software"
] |
57,757,193 | https://en.wikipedia.org/wiki/International%20Society%20for%20Research%20on%20Aggression | The International Society for Research on Aggression (abbreviated ISRA) is an international learned society dedicated to scientific research on all aspects of human aggressive behavior. It was established in August 1972 in Tokyo, Japan, by a group of academics who were there to attend the 20th Annual International Congress of Psychology. The Society was co-founded by Saul Rosenzweig and John Paul Scott, who served as its first and second president, respectively. Its official journal is Aggressive Behavior, which is published by John Wiley & Sons. The current president of the society is Barbara Krahé.
Presidents
Notable past presidents of the ISRA include:
Saul Rosenzweig (first president)
John Paul Scott (second president)
Dan Olweus (1995-1996)
Leonard Eron (1989–1991)
Craig A. Anderson (2010–2012)
References
External links
Organizations established in 1972
Aggression
International learned societies | International Society for Research on Aggression | [
"Biology"
] | 177 | [
"Behavior",
"Aggression",
"Human behavior"
] |
57,758,420 | https://en.wikipedia.org/wiki/NGC%201271 | NGC 1271 is a compact elliptical or lenticular galaxy located about 250 million light-years away in the constellation Perseus. The galaxy was discovered by astronomer Guillaume Bigourdan on November 14, 1884. NGC 1271 is a member of the Perseus Cluster and has a nuclear dust disk in its center. It also has an edge-on, intermediate-scale disk and has a central bulge. Like NGC 1277, NGC 1271 is a candidate "relic galaxy".
Supermassive black hole
Using orbital-based stellar dynamical models, Walsh et al. determined that the supermassive black hole in the center of NGC 1271 has a mass of .
See also
List of NGC objects (1001–2000)
NGC 1277
References
External links
Perseus Cluster
Perseus (constellation)
Elliptical galaxies
Lenticular galaxies
1271
12367
Astronomical objects discovered in 1884
Discoveries by Guillaume Bigourdan | NGC 1271 | [
"Astronomy"
] | 187 | [
"Perseus (constellation)",
"Constellations"
] |
57,759,485 | https://en.wikipedia.org/wiki/Sneathia%20amnii | Sneathia amnii is a bacterium from the genus of Sneathia which has been isolated from human blood from Strasbourg in France. Sneathia amnii is a pathogen of the female urogenital tract.
References
Fusobacteriota
Bacteria described in 2002 | Sneathia amnii | [
"Biology"
] | 61 | [
"Bacteria stubs",
"Bacteria"
] |
57,759,676 | https://en.wikipedia.org/wiki/Uncobasidium%20roseocremeum | Uncobasidium roseocremeum is a species of crust fungus in the family Meruliaceae. Found in South America, it was described as a new species in 2012 by mycologists Sergio Gorjón, Alina Greslebin, and Mario Rajchenberg. The holotype was collected in Nahuel Huapi National Park, Argentina, where it was found growing on the bark of a living tree of Saxegothaea conspicua. The specific epithet roseocremeum refers to the colour of the fruit body—cream with pinkish tints. Microscopic features of the fungus include its basidia that have two sterigma and lateral protuberances, encrusted hyphae that resemble paraphyses, and spherical spores.
References
Meruliaceae
Fungi described in 2012
Fungi of Argentina
Fungus species | Uncobasidium roseocremeum | [
"Biology"
] | 174 | [
"Fungi",
"Fungus species"
] |
57,760,000 | https://en.wikipedia.org/wiki/ZK-283197 | ZK-283197 (also known as BAY 86-5310 or SH-T04211C) is a selective and orally active ERβ agonist which was under development by Bayer Healthcare AG for the treatment of vasomotor symptoms. It reached phase II clinical trials prior to the discontinuation of its development. Its development was terminated in 2014.
References
Abandoned drugs
Drugs with undisclosed chemical structures
Selective ERβ agonists
Synthetic estrogens | ZK-283197 | [
"Chemistry"
] | 97 | [
"Drug safety",
"Abandoned drugs"
] |
57,760,315 | https://en.wikipedia.org/wiki/TLBleed | TLBleed is a cryptographic side-channel attack that uses machine learning to exploit a timing side-channel via the translation look-aside buffer (TLB) on modern microprocessors that use simultaneous multithreading. , the attack has only been demonstrated experimentally on Intel processors; it is speculated that other processors may also potentially be vulnerable to a variant of the attack, but no proof of concept has been demonstrated. AMD had indicated that their processors would not be vulnerable to this attack.
The attack led to the OpenBSD project disabling simultaneous multithreading on Intel microprocessors. The OpenBSD project leader Theo de Raadt has stated that, while the attack could theoretically be addressed by preventing tasks with different security contexts from sharing physical cores, such a fix is currently impractical because of the complexity of the problem.
See also
Transient execution CPU vulnerability
Zombieload
References
External links
Research Paper
2018 in computing
Hardware bugs
Intel x86 microprocessors
Side-channel attacks | TLBleed | [
"Technology"
] | 210 | [
"Computer security stubs",
"Computing stubs"
] |
57,760,585 | https://en.wikipedia.org/wiki/NNC%2045-0095 | NC 45-0095 is a synthetic nonsteroidal selective estrogen receptor modulator (SERM) which was under development by Novo Nordisk for the treatment of postmenopausal osteoporosis but was never marketed. It is a partial agonist of the estrogen receptor ( (for binding inhibition) = 9.5 nM; = 13 nM) with mixed estrogenic and antiestrogenic activity, and shows full estrogenic activity in bone and uterus ( (relative to moxestrol, in Ishikawa endometrial cancer cell line) = 105%). The compound is a pyrrolo indolizine derivative. Its development was discontinued by 2003.
See also
List of selective estrogen receptor modulators
References
Abandoned drugs
Indolizines
4-Hydroxyphenyl compounds
Pyrroles
Selective estrogen receptor modulators
Drugs developed by Novo Nordisk | NNC 45-0095 | [
"Chemistry"
] | 192 | [
"Drug safety",
"Abandoned drugs"
] |
57,760,778 | https://en.wikipedia.org/wiki/%CE%92-LGND2 | β-LGND2, also known as ERβ-selective ligand 2 or as GTx-878, is a synthetic nonsteroidal estrogen and selective ERβ agonist which was under development by GTx for the treatment of benign prostatic hyperplasia, prostatitis, and rheumatoid arthritis but was never marketed. It shows approximately 25-fold selectivity for activation of the ERβ over the ERα ( = 2 nM and 52 nM, respectively). β-LGND2 is an isoquinolinone derivative.
References
External links
GTx-878 - AdisInsight
Abandoned drugs
Bromoarenes
Isoquinolines
Ketones
4-Hydroxyphenyl compounds
Selective ERβ agonists
Synthetic estrogens
Hydroxyarenes | Β-LGND2 | [
"Chemistry"
] | 165 | [
"Ketones",
"Functional groups",
"Drug safety",
"Abandoned drugs"
] |
57,760,888 | https://en.wikipedia.org/wiki/Climacturia | Climacturia is urinary incontinence at the moment of sexual climax (orgasm). It can be a result of radical prostatectomy to treat prostate cancer. It is uncomfortable at times, but usually harmless.
References
Sexology
Urology
Oncology | Climacturia | [
"Biology"
] | 56 | [
"Behavior",
"Sexuality stubs",
"Sexology",
"Behavioural sciences",
"Sexuality"
] |
57,761,185 | https://en.wikipedia.org/wiki/WAY-204688 | WAY-204688, also known as SIM-688, is a synthetic nonsteroidal estrogen and nuclear factor κB (NF-κB) inhibitor which was originated by ArQule and Wyeth and was under development by Wyeth for the treatment of rheumatoid arthritis, non-specific inflammation, and sepsis but was never marketed. It is a "pathway-selective" estrogen receptor (ER) ligand which inhibits NF-κB with an of 122 nM and with maximal inhibition relative to estradiol of 94%. Inhibition of NF-κB by WAY-204688 appears to be dependent on agonism of the ERα, as it is reversed by the ERα antagonist fulvestrant, but is not dependent on the ERβ. In contrast to the case of NF-κB inhibition, WAY-204688 produces only slight elevation of creatine kinase in vitro, a measure of classical estradiol effects. It reached phase I clinical trials prior to the discontinuation of its development.
References
External links
SIM-688 (WAY-204688) - AdisInsight
4-Phenylpiperidines
Abandoned drugs
Biased ligands
Ethers
Ketones
1-Naphthyl compounds
Nitriles
Synthetic estrogens
Trifluoromethyl compounds | WAY-204688 | [
"Chemistry"
] | 285 | [
"Ketones",
"Drug safety",
"Functional groups",
"Signal transduction",
"Biased ligands",
"Organic compounds",
"Ethers",
"Nitriles",
"Abandoned drugs"
] |
57,761,321 | https://en.wikipedia.org/wiki/Rimostil | Rimostil (developmental code name P-081) is a dietary supplement and extract of isoflavones from red clover which was under development by Kazia Therapeutics (formerly Novogen) for the prevention of postmenopausal osteoporosis and cardiovascular disease and for the treatment of menopausal symptoms and hyperlipidemia but was never approved for medical use. It is enriched with isoflavone phytoestrogens such as formononetin, biochanin A, daidzein, and genistein, and is proposed to act as a selective estrogen receptor modulator, with both estrogenic and antiestrogenic effects in different tissues. The extract reached phase II clinical trials for cardiovascular disorders, hyperlipidemia, and postmenopausal osteoporosis prior to the discontinuation of its development in 2007.
See also
Femarelle
Menerba
References
External links
P-081 (Rimostil) - AdisInsight
Abandoned drugs
Botanical drugs
Dietary supplements
Herbalism
Isoflavones
Phytoestrogens
Selective estrogen receptor modulators | Rimostil | [
"Chemistry"
] | 234 | [
"Drug safety",
"Abandoned drugs"
] |
57,761,454 | https://en.wikipedia.org/wiki/ORG-201745 | ORG-201745 is a progestin which was originated by Organon and was under development by Schering-Plough (which acquired Organon in 2007) for the treatment of "female genital diseases" and as a hormonal contraceptive for the prevention of pregnancy but was never marketed.
References
Abandoned drugs
Drugs with undisclosed chemical structures
Hormonal contraception
Progestogens | ORG-201745 | [
"Chemistry"
] | 80 | [
"Drug safety",
"Abandoned drugs"
] |
57,761,492 | https://en.wikipedia.org/wiki/ORG-47241 | ORG-47241 is a progestin which was under development by Organon for the treatment of "female genital diseases" and as a hormonal contraceptive for the prevention of pregnancy but was never marketed.
References
Abandoned drugs
Drugs with undisclosed chemical structures
Hormonal contraception
Progestogens | ORG-47241 | [
"Chemistry"
] | 64 | [
"Drug safety",
"Abandoned drugs"
] |
57,761,568 | https://en.wikipedia.org/wiki/LG-2527 | LG-2527 is a nonsteroidal progestin which was under development by Ligand Pharmaceuticals and Wyeth for the treatment of menopausal symptoms and breast cancer, but was never marketed. It reached the preclinical stage of development prior to the discontinuation of its development in early 2001.
References
Abandoned drugs
Drugs with undisclosed chemical structures
Hormonal antineoplastic drugs
Progestogens | LG-2527 | [
"Chemistry"
] | 89 | [
"Drug safety",
"Abandoned drugs"
] |
57,761,673 | https://en.wikipedia.org/wiki/ASCE-ASME%20Journal%20of%20Risk%20and%20Uncertainty%20in%20Engineering%20Systems | The ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems is a peer-reviewed scientific journal established in 2014 by the American Society of Civil Engineers (ASCE) and the American Society of Mechanical Engineers (ASME). It disseminates research findings, best practices concerns, and discussions and debates on risk- and uncertainty-related issues in the areas of civil and mechanical engineering and related fields.
Scope
The journal covers risk and uncertainty issues in planning, design, construction/manufacturing, utilization, decommissioning and removal, and evaluation of engineering systems. The journal has wide coverage to all sub-disciplines of civil and mechanical engineering and other related fields, including structural engineering, geotechnical engineering, water resources engineering, construction engineering, transport engineering, coastal engineering, nuclear engineering, industrial and manufacturing engineering including gas, oil and chemical, ocean engineering, hazard analysis including climate change, earthquake engineering, associated resilience and sustainability, mechanics, mechatronics, robotics, thermodynamics, human factors, and thermo science.
History
Professor Bilal M. Ayyub from the Department of Civil and Environmental Engineering, University of Maryland College Park, established the ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems in 2014 in coordination and consultation with an advisory board representing leaders from ASCE and ASME, with the first issue being published in March 2015. As of 2018, it is the only joint journal for both societies with another society in their respective long histories. ASCE and ASME registered the two parts as separate journals as Part A and Part B, respectively, to facilitate the production of the journal along other journals offered by the respective societies. Both journals have the same editorial board and leadership and produced their first quarterly issues at the end of first quarter of 2015. The current Editor-in-Chief of the two journals is Professor Michael Beer.
Indexes
Both Part A and Part B are listed in the Emerging Sources Citation Index by Clarivate Analytics, formerly Thomson Reuters, and it is eligible for indexing in 2018. From 2016 onward, all articles are included in Web of Science. They are included also in Scopus. The current Impact Factor of Part A is 1.926. based on the latest Journal Citation Reports released by Clarivate Analytics.
References
External links
ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems, Part A website
ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems, Part B website
ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems, Part A & B website
American Society of Mechanical Engineers academic journals
American Society of Civil Engineers academic journals
Mechanical engineering journals | ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems | [
"Engineering"
] | 542 | [
"Mechanical engineering journals",
"Mechanical engineering"
] |
57,761,689 | https://en.wikipedia.org/wiki/Electroshapable%20material | Electroshapable materials are composite materials from the class of thermoplastic materials. Electroshapable materials are plastics rigid at room temperature, which can take the form of various objects or plastic elements. They can substitute for more common thermoplastic polymers such as PVC, PE, PC, EVA.
The particularity of electroshapable materials lies in their ability to become fluid and malleable when an electric voltage is applied to two ends of the material, before becoming rigid again after the voltage is removed. This process can be reversible. This behavior makes thermoforming fast, reversible and easy to use for many applications. One of the major benefits is the improved comfort of everyday products in contact with the human body.
Electroshapable materials are particularly useful in so-called thermoformable products, particularly in the field of sports equipment (e.g. ski boots, soles, body protections) and in the medical sector (e.g. splints).
Electroshapable materials should not be confused with electroactive polymers because they are not based on the same physical principle.
Physical principle
Electroshapable materials are based on a relatively simple physical principle: it is in fact an electrically conductive thermoplastic material in which are positioned two electrodes for applying an electrical voltage.
When an electrical voltage is applied, the polymer will act as a heating resistor because of its resistivity. It will heat up homogeneously by the Joule effect until it reaches its melting temperature, beyond which it becomes sufficiently viscous to be malleable to the hand.
Ideally the thermoplastic polymer selected has a relatively low melting temperature (60 °C for example) so that the user can handle it without danger of burning and to reduce the amount of energy required for the transition.
Any voltage can be used, both direct current and alternating current. However, the electric power required to do the rigid-malleable transition is proportional to the mass of electroshapable materials to be deformed. Depending on the mass of the element, it will be required a minimum electrical power to achieve the melting temperature. The current is determined by the resistance of the electroshapable element to melt. Thus by the geometry of the element and by the resistivity of the material.
History
Electrically conductive polymers or composites have existed since the 1970s.
However, the concept of electroshapable materials is quite recent; it was developed for the first time in France in 2015 by Pierre-Louis Boyer and Alexis Robert.
Uses
Lack of adaptation of mass produced products
Some rigid objects in contact with the human body have a need to adapt to the morphology of the user, in order to distribute the pressure over the entire human-object interface. In order to improve the comfort of the user and to avoid pressure points, which can cause bedsores.
This need to adapt rigid forms comes from the extreme variability of anatomy between individuals; most mass production processes are not adapted to meet this variability. Indeed, these methods are generally optimized to make a single shape, often from a mold or die (for example: plastic injection, metal foil stamping). To address this problem of morphological diversity, manufacturers often have to multiply industrial tools in order to offer several dimensions or shapes to their products. The most prominent example is shoes for which there can be up to fifteen to twenty different sizes. Which is very difficult to handle because:
Cost: Industrial tools such as injection molds are very expensive. Required investment is proportional to the number of reference.
Logistics: With an increasing number of references the stock management also becomes more complicated. Moreover, the manufacturers are very limited in number of product variations, because each is multiplying the number of references. For example, if a shoe manufacturer who proposes a model in fifteen sizes wishes to produce a product in three different colors, he will have to manage 3 × 15, or 45 references. If it wants to make two models, one for large foot and one for thin foot, it will double again to 90 references.
Limited by the number of variations, the designers can hardly answer all the anatomical specificities of the individuals. The most common strategic option is to address the products to the physical characteristics of the average individual, which is expected to match the majority of customers, but leaves a significant fringe of users unsatisfied.
Thermoformable products
The so-called thermoformable products (which use thermoplastic elements often at low melting temperature such as PCL) are a solution allowing products to adapt to the anatomy of the user.
Thermoformable products make it possible to adapt an initially standard shape to the anatomy of the user, making it possible to adapt more finely to each user than is possible through product variations. Many current applications use the principle of thermoforming, such as: ski boots, shoe soles, medical splints.
One of the limitations of these products using conventional thermoplastics is the equipment required for their implementation. Indeed, the heat energy required to raise the material to its melting point is generally provided by the use of an oven or a water bath.
The electroshapable materials also make it possible to form product to the user anatomy.
Advantages
Making the work easier for the end user, who simply needs to connect the product to a calibrated power source.
Speed of the forming process because the material heats intrinsically and homogeneously by Joule effect. So it can melt in seconds, making the whole forming process under a minute.
Disadvantages
Need for a power supply.
The use of a power supply requires compliance with safety standards, especially if the voltage used is greater than 50 V.
References
Sources
Shape changing polymers.
LOMA Innovation and its plastic forming technology.
A polymer forming with heat.
Patent describing the principle of electroformable polymers.
External links
Composite materials
Plastics
Polymers
Thermoplastics | Electroshapable material | [
"Physics",
"Chemistry",
"Materials_science"
] | 1,210 | [
"Unsolved problems in physics",
"Composite materials",
"Materials",
"Polymer chemistry",
"Polymers",
"Amorphous solids",
"Matter",
"Plastics"
] |
57,761,913 | https://en.wikipedia.org/wiki/LAG%20Insecte | The LAG Insecte is a portable keyboard which allows an artist to move around on stage while playing stationary electronic instruments. It was specially made in France for Jean-Michel Jarre in 1988 by LAG. Jarre used the keyboard in 1988 at the Docklands concert and in 1990 at La Défense concert. He also used it for the Industrial Revolution (overture) on the album Revolutions.
The Insescte is a 29-key MIDI controller, that is not capable of producing its own sounds. Instead it triggers up to 16 other instruments via standardized communication, known as MIDI. It contains an internal Z80 microprocessor and pitch bend (a control that lets the musician bend a note's pitch).
Design
The Insecte had a science-fiction design; it was meant to resemble an insect. The design was said to be inspired by the film Blade Runner, and drawings of Enki Bilal.
Microphone
A homemade Shure microphone used for the vocoder effect on the Jean-Michel Jarre track Revolution.
Construction
The white keys were constructed from wood and the black keys were constructed of sheathed leather. The case was also made of wood. The controllers and buttons were made of iron and aged plastic.
Concerts used in
Destination Docklands
Paris la Defense
External link
Photo of the instrument being played
References
Computer peripherals
Electronic musical instruments
MIDI
Products introduced in 1988 | LAG Insecte | [
"Technology"
] | 278 | [
"Computer peripherals",
"Components"
] |
57,763,003 | https://en.wikipedia.org/wiki/Broadcast%2C%20unknown-unicast%20and%20multicast%20traffic | Broadcast, unknown-unicast and multicast traffic (BUM traffic) is network traffic transmitted using one of three methods of sending data link layer network traffic to a destination of which the sender does not know the network address. This is achieved by sending the network traffic to multiple destinations on an Ethernet network. As a concept related to computer networking, it includes three types of Ethernet modes: broadcast, unicast and multicast Ethernet. BUM traffic refers to that kind of network traffic that will be forwarded to multiple destinations or that cannot be addressed to the intended destination only.
Overview
Broadcast traffic is used to transmit a message to any reachable destination in the network without the need to know any information about the receiving party. When broadcast traffic is received by a network switch it is replicated to all ports within the respective VLAN except the one from which the traffic comes from.
Unknown-unicast traffic happens when a switch receives unicast traffic intended to be delivered to a destination that is not in its forwarding information base. In this case the switch marks the frame for flooding and sends it to all forwarding ports within the respective VLAN. Forwarding this type of traffic can create unnecessary traffic that leads to poor network performance or even a complete loss of network service. This flooding of packets is known as a unicast flooding.
Multicast traffic allows a host to contact a subset of hosts or devices joined into a group. This causes the message to be broadcast when no group management mechanism is present. Flooding BUM frames is required in transparent bridging and in a data center context this does not scale well causing poor performance.
BUM traffic control
Throttling
One issue that may arise is that some network devices cannot handle high rates of broadcast, unknown-unicast or multicast traffic. In such cases, it is possible to limit the BUM traffic for specific ports in order to have a control on the number of packets or bytes that are flooded on the VLAN to other devices. This threshold is represented in kilobits per second (kbps), and it can be set for broadcast rate, multicast rate and unknown unicast rate independently.
Network port security
In the case of unknown-unicast traffic, a security issue may arise. To prevent flooding unknown-unicast traffic across the switch, it is possible to configure the network equipment to divert unknown-unicast traffic to specific trunk interfaces in order to split broadcast coming from different VLANs or to use specific trunk interfaces for multiple VLANs.
BUM handling in VXLAN
The use of VXLAN as overlay technology allows for providing data link layer connectivity services between endpoints that may be deployed across network layer network domains. Since those endpoints are logically part of the same data link layer domain, they must be capable of sending and receiving data link layer multi-destination frames (BUM traffic). BUM traffic can be exchanged across network layer network boundaries by encapsulating it into VXLAN packets addressed to a multicast group, so to leverage the network for traffic replication services.
In Data Plane Learning the broadcast traffic is flooded to multicast group members. In Control Plane Learning addresses are collected and forwarded via BGP. Broadcast traffic is reduced and VXLAN tunnel endpoints (VTEPs) reply to the caller directly.
VXLAN can handle BUM in two ways: Multicast and Head End Replication.
Multicast is the most common approach, and each VXLAN network identifier (VNI) is mapped to a single multicast group, while each multicast group may map to one or more VNIs. When a VTEP comes alive it uses the Internet Group Management Protocol to join the multicast groups for the VNIs it uses. When a VTEP has to send BUM traffic it will send it only to the relevant multicast group. This is a method for VTEP discovery.
Head End Replication is only available if using BGP EVPN. It is less efficient than multicast and does not scale well but it is simpler to implement if you do not have a multicast-enabled infrastructure. In Head End Replication, when BUM arrives, the VTEP creates several unicast packets and sends one to each VTEP that supports the VNI.
BUM handling in EVPN
Ethernet VPN (EVPN) and Provider Backbone Bridging EVPN (PBB-EVPN) provide Ethernet multipoint services over MPLS networks. In EVPN operations, the Provider Edge (PE) routers automatically discover each other when connected on the same Ethernet segment and select a Designated Forwarder (DF) responsible for forwarding BUM traffic.
In a VXLAN-EVPN, MAC learning occurs via the control plane instead of data plane. Furthermore, it is accepted only traffic from VTEPs whose information is learnt via the control plane, otherwise it is dropped. This presents a secure fabric where traffic will only be forwarded between VTEPs validated by the control plane.
See also
Transparent bridging
References
Computer networking
Ethernet
Network topology | Broadcast, unknown-unicast and multicast traffic | [
"Mathematics",
"Technology",
"Engineering"
] | 1,037 | [
"Computer networking",
"Computer engineering",
"Network topology",
"Computer science",
"Topology"
] |
62,046,844 | https://en.wikipedia.org/wiki/Yang%20Liming | Yang Liming (; 5 February 1919 – 12 January 2003), also known as Li-Ming Yang, was a Chinese theoretical physicist and professor at Peking University. A doctoral student of the Nobel laureate Max Born, he made contributions to the research of nuclear shell structure, many-body theory, and the interacting boson model. He was elected an academician of the Chinese Academy of Sciences in 1991, together with his wife, computer scientist Xia Peisu.
Early life and education
Yang was born on 5 February 1919 in Lishui County, Jiangsu, Republic of China. When he was in high school, the Second Sino-Japanese War broke out and Lishui was occupied by the Imperial Japanese Army. Yang became a war refugee and fled across China, finally arriving in Sichuan half a year later. There he completed his secondary education at National No. 2 High School of Hechuan and entered National Central University, then exiled in Chongqing, in 1938. After graduating four years later with a degree in mechanics, he worked at Central Mechanics Factory in Kunming for a year, before returning to National Central University as an assistant professor.
Career in the United Kingdom
In 1944, Yang passed the government examination for study abroad, and was sent to the United Kingdom in 1945, where he worked and trained at Renold Works. In 1946, Max Born accepted him as a graduate student at the University of Edinburgh. Yang earned his Ph.D. in theoretical physics in just two years, and continued to conduct postdoctoral research under Born afterwards. He published six papers in the field, including "Nuclear Shell Structure and Nuclear Density" which explains the recently discovered magic numbers for nucleons.
Career in China
Two years after the founding of the People's Republic of China, Yang and his wife Xia Peisu returned to China in 1951. They both became faculty members at Tsinghua University, although Yang was soon transferred to Peking University during Communist China's reorganization of higher education on the Soviet model in 1952. At Peking University he served as associate professor, professor, and later doctoral advisor. In the late 1950s, he and Yu Min co-authored a textbook on the theories of nuclear physics.
Starting in the late 1950s, Yang advanced many-body theory in condensed matter physics, which was pioneered by Keith Brueckner. In the 1970s, he conducted research and proposed new theories for the interacting boson model (IBM). In 1985, he taught as a visiting professor at Yale University on the invitation of Francesco Iachello, a co-inventor of IBM. He taught at the Technical University of Munich in 1986, and collaborated with Akito Arima, the other co-inventor of IBM in Japan.
Over a teaching career spanning more than four decades, Yang educated a large number of students, including more than 30 doctoral and master's students. In 1991, Yang Liming and his wife Xia Peisu were both elected as academicians of the Chinese Academy of Sciences.
Personal life
In 1945, Yang met Xia Peisu, an alumna of National Central University. They married in 1950, when they were both studying at the University of Edinburgh. She later became a pioneering computer scientist, acclaimed as the "mother of computer science" in China. The couple had two sons, Yang Yuenian and Yang Yuemin. The children followed the footsteps of their parents: Yuenian became a computer scientist, and Yuemin a physicist.
Yang died on 12 January 2003, aged 83.
References
1919 births
2003 deaths
Alumni of the University of Edinburgh College of Science and Engineering
Chinese expatriates in the United Kingdom
Members of the Chinese Academy of Sciences
National Central University alumni
Scientists from Nanjing
Physicists from Jiangsu
Academic staff of Peking University
Theoretical physicists
Second Sino-Japanese War refugees | Yang Liming | [
"Physics"
] | 762 | [
"Theoretical physics",
"Theoretical physicists"
] |
62,047,186 | https://en.wikipedia.org/wiki/Kotzig%27s%20theorem | In graph theory and polyhedral combinatorics, areas of mathematics, Kotzig's theorem is the statement that every polyhedral graph has an edge whose two endpoints have total degree at most 13. An extreme case is the triakis icosahedron, where no edge has smaller total degree. The result is named after Anton Kotzig, who published it in 1955 in the dual form that every convex polyhedron has two adjacent faces with a total of at most 13 sides. It was named and popularized in the west in the 1970s by Branko Grünbaum.
More generally, every planar graph of minimum degree at least three either has an edge of total degree at most 12, or at least 60 edges that (like the edges in the triakis icosahedron) connect vertices of degrees 3 and 10.
If all triangular faces of a polyhedron are vertex-disjoint, there exists an edge with smaller total degree, at most eight.
Generalizations of the theorem are also known for graph embeddings onto surfaces with higher genus.
The theorem cannot be generalized to all planar graphs, as the complete bipartite graphs and have edges with unbounded total degree. However, for planar graphs with vertices of degree lower than three, variants of the theorem have been proven, showing that either there is an edge of bounded total degree or some other special kind of subgraph.
References
Planar graphs
Theorems in graph theory | Kotzig's theorem | [
"Mathematics"
] | 298 | [
"Statements about planar graphs",
"Planar graphs",
"Theorems in discrete mathematics",
"Planes (geometry)",
"Theorems in graph theory"
] |
62,047,555 | https://en.wikipedia.org/wiki/Christiane%20Koch | Christiane P. Koch is a German physicist whose research involves quantum mechanical versions of control theory, including the use of lasers to achieve coherent control of chemical reactions. She has also performed research on efficiently testing the accuracy of quantum computing devices. She is a professor at the Free University of Berlin.
Education and career
Koch studied physics at the Humboldt University of Berlin from 1992 to 1998, during which she was a Fulbright Scholar at the University of Texas at Austin. She did her doctoral studies in chemical physics through Humbold University at the Fritz Haber Institute of the Max Planck Society, completing her Ph.D. in 2002.
After postdoctoral study at the University of Paris-Sud and The Hebrew University of Jerusalem, she became an Emmy Noether Independent Junior Researcher at the Free University of Berlin in 2006. She became a professor at Kassel in 2010, and moved to the Free University of Berlin in 2019.
Recognition
In 2002, Koch won the Otto Hahn Medal of the Max Planck Society.
References
Year of birth missing (living people)
Living people
Humboldt University of Berlin alumni
Academic staff of the Free University of Berlin
Academic staff of the University of Kassel
21st-century German physicists
German women physicists
Control theorists | Christiane Koch | [
"Engineering"
] | 240 | [
"Control engineering",
"Control theorists"
] |
62,048,514 | https://en.wikipedia.org/wiki/ProcDump | ProcDump is a command-line application used for monitoring an application for CPU spikes and creating crash dumps during a spike. The crash dumps can then be used by an administrator or software developer to determine the cause of the spike. ProcDump supports monitoring of hung windows and unhandled exceptions. It can also create dumps based on the values of system performance counters.
Overview
Initially, ProcDump was only available for Microsoft Windows. In November 2018, Microsoft confirmed it is porting Sysinternals tools, including ProcDump and ProcMon, to Linux. The software is open source. It is licensed under MIT License and the source code is available on GitHub.
The Linux version requires Linux kernels version 3.5+ and runs on Red Hat Enterprise Linux / CentOS 7,
Fedora 26, Mageia 6, Ubuntu 14.04 LTS. It currently does not have full feature parity with the Windows version (e.g. custom performance counters).
Example
Create 5 core dumps 10 seconds apart of the target process with process identifier (pid) == 1234
$ sudo procdump -n 5 -p 1234
See also
WinDbg
Dr. Watson (debugger)
kdump (Linux)
ktrace
Process Explorer
References
External links
ProcDump - Windows Sysinternals | Microsoft Docs
GitHub - microsoft/ProcDump-for-Linux: A Linux version of the ProcDump Sysinternals tool
Command-line software
Free software programmed in C
Microsoft free software
Software using the MIT license
Unix programming tools
Windows administration | ProcDump | [
"Technology"
] | 336 | [
"Command-line software",
"Computing commands"
] |
62,048,793 | https://en.wikipedia.org/wiki/Antimony%20electrode | The antimony electrode has been investigated for its ability to function as a pH electrode. The electrode is made of elemental antimony. The electrochemical process can be formulated as
Sb2O3(s) + 6 H+ + 6 e− 2Sb(s) + 3H2O
The oxide, Sb2O3, is present on the surface of the electrode. Although this electrode does not give measurements of high accuracy, its rapid response, simplicity and rugged construction make it useful for continuous industrial pH monitoring. It can be used at elevated temperatures.
In an unusual application, an antimony electrode was used to measure pH inside the human stomach. The simplicity of construction meant that the electrode could be made small enough to be swallowed. Thin copper wires were attached to the electrode and one terminal on a pH meter. The subject's foot was placed in a saline solution. A calomel reference electrode was also placed in this solution and was connected to the other terminal on the meter. Antimony electrodes continue to be used for in vivo measurements. The use of antimony-based electrodes for analytical determinations has been reviewed.
Antimony electrodes are available commercially. They can be employed with solutions containing hydrofluoric acid for which the glass electrode cannot be used because of the reaction of glass with solutions containing hydrogen fluoride.
References
Electrodes
Electroanalytical chemistry devices | Antimony electrode | [
"Chemistry"
] | 282 | [
"Electroanalytical chemistry",
"Electrodes",
"Electrochemistry",
"Electroanalytical chemistry devices",
"Electrochemistry stubs",
"Physical chemistry stubs"
] |
62,051,454 | https://en.wikipedia.org/wiki/Teaghrelins | Teaghrelins are acylated flavonoid tetraglycosides found in semi-oxidized oolong teas (Camellia sinensis), such as Chin-shin oolong tea and Shy‐jih‐chuen oolong tea.
Teaghrelins are ghrelin receptor agonists in vitro. In an animal model, teaghrelins induce hunger and accelerate gastric emptying. Teaghrelins also has growth hormone releasing activity on the anterior pituitary gland, similar to the synthetic ghrelin analog GHRP-6, that could be inhibited by a ghrelin receptor antagonist.
References
Flavonoid glycosides
Ghrelin receptor agonists | Teaghrelins | [
"Chemistry"
] | 154 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
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