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14,517,517 | https://en.wikipedia.org/wiki/GPR3 | G-protein coupled receptor 3 is a protein that in humans is encoded by the GPR3 gene. The protein encoded by this gene is a member of the G protein-coupled receptor family of transmembrane receptors and is involved in signal transduction.
GPR3 mRNA is broadly expressed in neurons in various brain regions, including the cortex, thalamus, hypothalamus, amygdala, hippocampus, pituitary, and cerebellum. GPR3 mRNA is also expressed in the eye, lung, kidney, liver, testes, and ovary, among other tissues.
Individuals afflicted by Alzheimer's disease have in many cases, overexpression of the GPR3 protein in their neurons.
Function
GPR3 activates adenylate cyclase in the absence of ligand. GPR3 was first described as a constitutive activator of adenylate cyclase. This constitutive activity could be due to stimulation by a ubiquitous ligand that may be free, membrane-bound, or membrane-derived. Alternatively, they propose that this could also be due to basal Gs coupling. Various groups have since supported this initial finding of GPR3 constitutive activation and have proceeded to show similar Gs activity in GPR6 and GPR12.
GPR3 is expressed in mammalian oocytes where it maintains meiotic arrest and is thought to be a communication link between oocytes and the surrounding somatic tissue. It has been proposed that sphingosine 1-phosphate (S1P) and sphingosylphosphorylcholine (SPC) are GPR3 ligands, however this result was not confirmed in a β-arrestin recruitment assay.
Mice lacking GPR3 were found to develop late-onset obesity owing to decreased UCP-1 expression in brown adipose tissue and reduced thermogenic capacity.
Brown adipose tissue Activation
Brown adipose tissue (BAT), in contrast to bona fide white fat, can dissipate significant amounts of chemical energy through uncoupled respiration and heat production (thermogenesis). Metabolic substrates are consumed to fuel mitochondrial futile cycles and uncoupling protein 1 (UCP1)-dependent respiration to ultimately convert chemical energy to heat. Gs-signaling stimulates the recruitment of thermogenically competent beige adipocytes in the subcutaneous adipose depots.
Exposure to environmental cold stimulates thermogenic catabolism of lipids and carbohydrates in brown adipose tissue (BAT).
BAT activation is predominantly ascribed to the Gs-coupled family, which signals through increased cyclic AMP (cAMP). This class is exemplified by the β-adrenergic receptors (ADRB1, ADRB2, and ADRB3), which represent the canonical means of sympathetic, ligand-mediated thermogenic control.
However, in the case of Gpr3, cold exposure increases the expression of this constitutively active receptor, which possesses innate signaling capacity and, thus, can modulate cAMP levels and thermogenic output without a ligand.
Gpr3 expression must be kept at extremely low basal levels until there is a thermogenic demand. Mimicking the cold induction of Gpr3 is then sufficient to drive and maintain elevated BAT activity even under conditions of little or no sympathetic tone.
To prove this, OS Johansen and colleagues developed a conditional gain-of-function model (Gpr3 TTG) for robust and sustained genetic manipulation of Gpr3 in vitro and in vivo.
Gpr3 TTG mice were crossed with mice to facilitate overexpression of Gpr3 in isolated primary brown and subcutaneous white adipocytes. Gpr3 overexpression significantly increased the expression of thermogenic genes, fatty acid uptake, and basal and leak mitochondrial respiration.
Gpr3 overexpression in their primary adipocyte model suppressed expression of the β-adrenergic receptors, further supporting a counter-regulatory interaction between GPR3 and other Gs-coupled receptors.
BAT-specific overexpression of Gpr3 (C-3BO) mice were completely protected from developing diet-induced obesity despite maintaining comparable levels of food intake, C-3BO mice maintained elevated whole-body energy expenditure as well as darker brown BAT depots and higher thermogenic gene expression.
Reproductive system
In mammalian oocytes, the process of meiotic arrest and meiotic maturation is controlled by in large part by cAMP concentrations in the cell. When cAMP levels in the cell decrease the process of miosis resumes and this precedes germinal vesicle breakdown. It is proposed That GPR3 is implicated in cAMP signaling in oocytes since it is consistent with the observation that their mRNA expression is reduced when cAMP is chronically increased in oocytes. The constitutive activity of these receptors is sufficient to prevent maturation in mouse oocytes, it is shown that their activity is also sufficient for maintaining the meiotic arrest in the follicle.
Brain cells
GPR3 mRNA is broadly expressed in neurons in various brain regions, including the cortex, thalamus, hypothalamus, amygdala, hippocampus, pituitary, and cerebellum. Notably, the GPR3 protein is overexpressed in neurons in post-mortem brain tissue sections from individuals afflicted by Alzheimer's disease. In a study on mice with Alzheimer's disease, it was shown that the disruption of the expression of GPR3 has affected the overgrowth of amyloid plaque on neurons, helping symptoms of Alzheimer's disease.
Ligands
GPR3 is largely known as an orphan G protein-coupled receptor. Even though it does not have any endogenous ligands there is research being conducted to find non-endogenous agonists for the receptor.
Agonists
Sphingosine 1-phosphate
The molecule Sphingosine 1-phosphate (S1P) is a signaling lipid that exists in the extracellular plasma, its synthesis is catalysed by sphingosine kinases (SphKs). The molecule is reported to have high affinity to the GPR3 receptor. The proposed ligand activates the Gs signaling pathway in oocytes.
Diphenyleneiodonium chloride
Diphenyleneiodonium chloride (DPI) is an inhibitor of NADPH oxidase and a potent, irreversible, and time and temperature-dependent iNOS/eNOS inhibitor. Diphenyleneiodonium chloride (DPI) also functions as a TRPA1 activator and selectively inhibits intracellular reactive oxygen species (ROS). Diphenyleneiodonium chloride (DPI) was identified as a novel agonist of GPR3 with weak or no cross-reactivity with other GPCRs. DPI was further characterized to activate several GPR3-mediated signal transduction pathways, including Ca(2+) mobilization, cAMP accumulation, membrane recruitment of β-arrestin2, and receptor desensitization.
Inverse agonists
Cannabidiol
Cannabidiol (CBD) is a Phyto-cannabinoid found in the cannabis plant. This compound is connected to improving anxiety, cognition, and pain. Although it is orphan, GPR3 is phylogenetically most closely related to the cannabinoid receptors. Using β-arrestin2 recruitment and cAMP accumulation assays, it was recently found that cannabidiol is an inverse agonist for GPR3. The affects that the inverse agonist has are still unknown.
Evolution
Paralogues
Source:
GPR6
GPR12
S1PR5
LPAR2
S1PR1
S1PR2
LPAR3
LPAR1
CNR1
S1PR3
MC3R
MC4R
S1PR4
MC5R
MC1R
CNR2
MC2R
GPR119
References
Further reading
G protein-coupled receptors | GPR3 | [
"Chemistry"
] | 1,663 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,517,625 | https://en.wikipedia.org/wiki/Melatonin%20receptor%201B | Melatonin receptor 1B, also known as MTNR1B, is a protein that in humans is encoded by the MTNR1B gene.
Function
This gene encodes the MT2 protein, one of two high-affinity forms of a receptor for melatonin, the primary hormone secreted by the pineal gland. This gene product is an integral membrane protein that is a G-protein coupled, 7-transmembrane receptor. It is found primarily in the retina and brain; however, this detection requires RT-PCR. It is thought to participate in light-dependent functions in the retina and may be involved in the neurobiological effects of melatonin. Besides the brain and retina this receptor is expressed on the bone forming cells where it regulates their function in depositing bone.
Clinical significance
Several studies have identified MTNR1B receptor mutations that are associated with increased average blood sugar level and around a 20 percent elevated risk of developing type 2 diabetes. MTNR1B mRNA is expressed in human islets, and immunocytochemistry confirms that it is primarily localized in beta cells in islets.
Ligands
The following MT2R ligands have selectivity over MT1R:
Compound 3d: antagonist with sub-nM affinity
Compound 18f: antagonist and compound 18g partial agonist: sub-nM affinity, >100-fold selectivity over MT1
Compound 14: antagonist
Compound 13: agonist
See also
Melatonin receptor
Discovery and development of melatonin receptor agonists
References
Further reading
External links
G protein-coupled receptors
Human proteins
1B | Melatonin receptor 1B | [
"Chemistry"
] | 327 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,517,678 | https://en.wikipedia.org/wiki/Melanin-concentrating%20hormone%20receptor%201 | Melanin-concentrating hormone receptor 1, also known as MCH1, is one of the melanin-concentrating hormone receptors found in all mammals.
The protein encoded by this gene, a member of the G protein-coupled receptor family 1, is an integral plasma membrane protein which binds melanin-concentrating hormone. The encoded protein can inhibit cAMP accumulation and stimulate intracellular calcium flux, and is probably involved in the neuronal regulation of food consumption. Although structurally similar to somatostatin receptors, this protein does not seem to bind somatostatin.
Function
MCH1 is thought to have a number of functions including in the regulation of appetite, and in stress, anxiety and depression.
Selective ligands
Agonists
Melanin concentrating hormone (MCH)
S-36057 - modified MCH 6-13 fragment substituted with 3-iodotyrosine at N-terminus via dioxyoctanoyl linker, used as 125I radioligand for mapping MCH1 in vivo.
LK-184 (Procter & Gamble) is one pick
Antagonists
ATC-0065
ATC-0175
GW-803,430
NGD-4715
SNAP-7941
SNAP-94847
T-226,296
See also
Melanin-concentrating hormone receptor
References
Further reading
External links
G protein-coupled receptors
Human proteins | Melanin-concentrating hormone receptor 1 | [
"Chemistry"
] | 282 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,517,823 | https://en.wikipedia.org/wiki/Melanin-concentrating%20hormone%20receptor%202 | Melanin-concentrating hormone receptor 2 (MCH2) also known as G-protein coupled receptor 145 (GPR145) is a protein that in humans is encoded by the MCHR2 gene.
MCH2 is also found in dogs, ferrets, and some other primates and carnivores, but is not found in mice or rats. This has delayed research into the receptor as a therapeutic target, due to most early pharmaceutical research usually being conducted in small mammals such as mice, rats or rabbits which lack the MCH2 gene and its receptor product.
Clinical significance
Treatment of human cells expressing MCHR2 with MCH resulted in upregulation of IDH3A, PCK1 and PFKFB4 and the downregulation of INSIG2 and ACOT8.
See also
Melanin-concentrating hormone receptor
References
External links
Further reading
G protein-coupled receptors
Human proteins | Melanin-concentrating hormone receptor 2 | [
"Chemistry"
] | 190 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,520,493 | https://en.wikipedia.org/wiki/Agate%20%28typography%29 | An agate (US) or ruby (UK) is a unit of typographical measure. It is 5.5 typographical points, or about inch (1.94 mm). It can refer either to the height of a line of type or to a font that is 5.5 points. An is commonly used to display statistical data or legal notices in newspapers. It is considered to be the smallest point size that can be printed on newsprint and remain legible.
Due to the small size of agate compared to typical newspaper body text that might be 8 to 10 points and due to its use for statistical, stock, racing or other table uses, the term "agate" may also refer to tables and texts using this point size. The general description "agate" refers to the collection of miscellaneous tables, stock tables, horse racing and sports tables and so forth that may be in a newspaper.
From the American Dictionary of Printing and Bookmaking (1894):
See also
Traditional point-size names
References
Typography
Units of length
Typesetting | Agate (typography) | [
"Mathematics"
] | 220 | [
"Quantity",
"Units of measurement",
"Units of length"
] |
14,520,624 | https://en.wikipedia.org/wiki/Jay%20Nunamaker | Jay F. Nunamaker Jr. (born August 27, 1937) is Regents Professor and Soldwedel Professor at the University of Arizona. Regents Professor is the highest faculty rank bestowed at the university, an honor reserved for the top 3% of scholars.
He founded both the MIS department (ranked top 5 in the country by U.S. News & World Report for the past 20 years) in 1974, and the Center for the Management of Information in 1985 at the University of Arizona.
Biography
Nunamaker has served as major professor to over 80 doctoral students from 1968–present. Students that currently hold, or have held, positions at Harvard, University of Michigan, Indiana University, University of Iowa, University of Florida, University of Georgia, University of Washington, Carnegie Mellon University, Texas A&M University, University of Hawaii, and other top MIS institutions.
Jay Nunamaker has been featured in the July 1997 Forbes magazine issue on technology as one of eight key innovators in information technology.
In 2002, he was the recipient of the LEO (lifetime achievement) Award from the Association of Information Systems, at ICIS in Barcelona, Spain.
In a 2005 article in Communications of the Association for Information Systems, he was recognized as one of the most productive information systems researchers, ranking no. 4 to 6 for the period from 1991-2003 based on the number of papers in top IS journals.
Work
His multidisciplinary research is built on a foundation of computer supported collaboration, decision support, deception detection and determination of intent.
Nunamaker's research has led to major breakthroughs in collaboration, decision support systems, and automated systems analysis and design, and he is known for testing his theories and systems in the “real world.”
He built the first operational decision support center in 1985; there are over 2,500 decision centers in industry, government and universities using the GroupSystems software developed at the University of Arizona.
His research on group support systems addresses behavioral as well as engineering issues and focuses on theory as well as implementation.
Publications
His publications span more than 250 papers and seven books, and editorial positions on major journals, in computer science and engineering, information management, communication, security informatics.
References
Further reading
External links
Website at arizona.edu.
1937 births
Living people
Information systems researchers
University of Pittsburgh alumni
Carnegie Mellon University alumni
Case Western Reserve University alumni
Purdue University faculty
University of Arizona faculty | Jay Nunamaker | [
"Technology"
] | 489 | [
"Information systems",
"Information systems researchers"
] |
14,520,910 | https://en.wikipedia.org/wiki/Blacker%20%28security%29 | Blacker (styled BLACKER) is a U.S. Department of Defense computer network security project designed to achieve A1 class ratings (very high assurance) of the Trusted Computer System Evaluation Criteria (TCSEC).
The first Blacker program began in the late 1970s, with a follow-on eventually producing fielded devices in the late 1980s. It was the first secure system with trusted end-to-end encryption on the United States' Defense Data Network.
The project was implemented by SDC (software), and Burroughs (hardware), and after their merger, by the resultant company Unisys.
See also
RED/BLACK concept for segregation of sensitive plaintext information (RED signals) from encrypted ciphertext (BLACK signals)
References
Computer network security
Cryptography
Secure communication
Security engineering
Trusted computing
United States Department of Defense information technology | Blacker (security) | [
"Mathematics",
"Technology",
"Engineering"
] | 171 | [
"Cybersecurity engineering",
"Systems engineering",
"Cryptography",
"Security engineering",
"Computer network stubs",
"Applied mathematics",
"Computer networks engineering",
"Trusted computing",
"Computer network security",
"Computing stubs"
] |
14,522,267 | https://en.wikipedia.org/wiki/Cysteinyl%20leukotriene%20receptor%202 | Cysteinyl leukotriene receptor 2, also termed CYSLTR2, is a receptor for cysteinyl leukotrienes (LT) (see leukotrienes#Cysteinyl leukotrienes). CYSLTR2, by binding these cysteinyl LTs (CysLTs; viz, LTC4, LTD4, and to a much lesser extent, LTE4) contributes to mediating various allergic and hypersensitivity reactions in humans. However, the first discovered receptor for these CsLTs, cysteinyl leukotriene receptor 1 (CysLTR1), appears to play the major role in mediating these reactions.
Gene
The human gene maps to the long arm of chromosome 13 at position 13q14, a chromosomal region that has long been linked to asthma and other allergic diseases. The gene consists of four exons with all introns located in the genes' 5' UTR region and the entire coding region located in the last exon. CysLTR2 encodes a protein composed of 347 amino acids and shows only modest similarity to the CysLTR1 gene in that its protein shares only 31% amino acid identity with the CysLTR1 protein.
Receptor
CySLTR2 mRNA is co-expressed along with CysLRR1 in human blood eosinophils and platelets, and tissue mast cells, macrophages, airway epithelial cells, and vascular endothelial cells. It is also expressed without CysLTR1 throughout the heart, including Purkinje cells, adrenal gland, and brain as well as some vascular endothelial, airway epithelial, and smooth muscle cells.
CysLTR2, similar to CysLTR1, is a G protein–coupled receptor that links to and when bound to its CysLT ligands activates the Gq alpha subunit and/or Ga subunit of its coupled G protein, depending or the cell type. Acting through these G proteins and their subunits, ligand-bound CysLTR1 activates a series of pathways that lead to cell function (see Gq alpha subunit#function and Ga subunit#function for details); the order of potency of the cysLTs in stimulating CysLTR2 is LTD4=LTC4>LTE4 with LTE4 probably lacking sufficient potency to have much activity that operates through CysLTR1 in vivo. By comparison, the stimulating potencies of these CysLTs for CysLTR1 is LTD4>LTC4>LTE4 with LTD4 showing 10-fold greater potency on CysLTR1 than CysLTR2. Perhaps related to this difference in CysLT sensitivities, cells co-expressing CysLTR2 and CysLTR1 may exhibit lower sensitivity to LTD4 than do cells expressing only CysLTR1; in consequence, CysLTR2 has been suggested to dampen CysLTR1's activities.
In addition to CysLTR1, GPR99 (also termed the oxoglutarate receptor or, sometimes, CysLTR3) appears to be an important receptor for CysLTs, particularly for LTE4: the CystLTs show relative potencies of LTE4>LTC4>LTD4 in stimulating GPR99-bearing cells and GPR99-deficient mice exhibit a dose-dependent loss of vascular permeability responses in skin to LTE4 but not to LTC4 or LTD4.
Other studies on model cells for allergy have defined GPR17 (also termed the uracil nucleotide/cysteinyl leukotriene receptor) as a receptor not only uracil nucleotides but also for CysLTs, with CysLTs having the following potencies LTD4>LTC4>LTE4 in stimulating GPR17-bearing cells. However, recent studies also working with model cells involved in allergy find that GPR17-bearing cells do not respond to these CysLTs (or uracil nucleotides). Rather, they find that: a) cells expressing both CysLTR1 and GPR17 receptors exhibit a marked reduction in binding and responding to LTD4 and b) mice lacking GPR17 are hyper-responsive to igE in a model for passive cutaneous anaphylaxis. The latter studies conclude that GPR17 acts to inhibit CysLTR1. Finally, and in striking contrast to these studies, repeated studies on neural tissues find that Oligodendrocyte progenitor cells express GPR17 and respond through this receptor to LTC4, LTD4, and certain purines (see GPR17#Function).
CysLTR2 inhibitors
There are as yet no selective inhibitors of CysLTR2 that are in clinical use (see Clinical significance section below). However, Gemilukast (ONO-6950) reportedly inhibits both CysLTR1 and CysLTR2. The drug is currently being evaluated in phase II trials for the treatment of asthma.
CysLTR2 polymorphism
Polymorphism in the CysLTR2'' gene resulting in a single amino acid substitution, M201V (i.e. amino acid methionine changed for valine at the 201 position of CysLTR2 protein) has been negatively associated in Transmission disequilibrium testing with the inheritance of asthma in separate populations of: a) white and African-Americans from 359 families with a high prevalence of asthma in Denmark and Minnesota, USA, and b)''' 384 families with a high prevalence of asthma from the Genetics of Asthma International Network. The M201V CysLTR2 variant exhibits decreased responsiveness to LTD4 suggesting that this hypo-responsiveness underlies its asthma transmission-protecting effect. A -1220A>C (i.e. nucleotide adenine substituted for cytosine at position 1220 upstream from the transcription start site) gene polymorphism variant in intron III the upstream region of CysLTR2 has been associated significantly with development of asthma in a Japanese population; the impact of this polymorphism on the genes expression or product has not been determined. These results suggest that CYSLTR2 contributes to the etiology and development asthma and that drugs targeting CYSLTR2 may work in a manner that differs from those of CYSLTR1 antagonists.
Clinical significance
The CysLT-induced activation of CysLTR2 induces many of the same in vitro responses of cells involved in allergic reactions as well as the in vivo allergic responses in animal models as that induced by CysLT-induced CysLTR1 (see Cysteinyl leukotriene receptor 1#Receptor. However, CysLT2 requires 10-fold higher concentrations of LTD4, the most potent cysLT for CysLTR1, to activate CysLTR2. Furthermore, the allergic and hypersensitivity responses of humans and animal models are significantly reduced by chronic treatment with Montelukast, Zafirlukast, and Pranlukast, drugs which are selective receptor antagonists of CysLTR1 but not CysLTR2. Models of allergic reactions in Cysltr2-deficient mice as well as in a human mast cell line indicate that mouse Cysltr2 and its human homolog CysLTR2 act to inhibit Cysltr1 and CysLTR1, respectively, and therefore suggest that CysLTR2 may similarly inhibit CysLTR1 in human allergic diseases. The role of CysLTR2 in the allergic and hypersensitivity diseases of humans must await the development of selective CysLTR2 inhibitors.
See also
Cysteinyl leukotriene receptor 1
Eicosanoid receptor
GPR99
References
Further reading
External links
G protein-coupled receptors | Cysteinyl leukotriene receptor 2 | [
"Chemistry"
] | 1,633 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,522,300 | https://en.wikipedia.org/wiki/Susana%20L%C3%B3pez%20Charret%C3%B3n | Susana López Charretón (born 19 June 1957) is a Mexican virologist specialized in understanding the mechanisms of infection of rotavirus. López Charretón has led a research program as principal investigator at the Biotechnology Institute (UNAM) in Cuernavaca, Mexico for over 25 years.
From 2000 to 2010, she was a Howard Hughes Medical Institute International Research Scholar.
In 2012, López Charretón received the L'Oréal-UNESCO Award for Women in Science – Latin America "for identifying how rotaviruses cause the death of 600,000 children each year".
Early life and education
Susana López Charretón was born in Mexico City in 1957. López Charretón knew from a young age that she wanted to pursue biology. López Charretón followed her passion for Biology and enrolled into the Universidad Nacional Autónoma de México (UNAM), where she completed her bachelor's in basic biomedical research in 1980, followed by a masters in 2003 and a PhD in 2006. While finishing her graduate degrees, she spent a few years at the California Institute of Technology (Caltech).
López Charretón holds a bachelor's degree (1980), a master's degree (1983) and a doctorate degree (1986) in basic biomedical research from the National Autonomous University of Mexico (UNAM) and currently works for the Institute of Biotechnology of the same university.
Research interests
López Charretón has led her research program as principal investigator at the Biotechnology Institute (UNAM) in Cuernavaca, Mexico. López Charretón serves as a mentor for master's and PhD students, and currently holds a SNI level III investigator status. Throughout her career, López Charretón has made advancements in our understanding of rotavirus. One of the most important findings from López Charretón research group is related to viral entry into a human body. Rotavirus is spread through the mouth and skin, but the virus leaves those cells alone and only infects and reproduces in cells in the small intestine. She has additionally studied how the rotavirus spreads in human populations, the immune response to it, and its replication cycle. This work has contributed to new diagnostic tests, isolation of new strains, and efforts towards a vaccine. She's published more than 130 papers in international journals. She also spent nearly nine years serving on the editorial board for the Journal of Virology.
From 2000 to 2010, she was a Howard Hughes Medical Institute International Research Scholar.
Awards and recognition
López Charretón won the Gabino Barreda Medal from UNAM in 1988 for her PhD research. In 1991, she was a Fogarty Fellow. López Charretón won the Funsalud Biennial Award in Gastrointestinal Diseases from the Mexican Foundation for Health in 2000 and 2002. In 2001, she was awarded the Carlos J. Finlay Prize for Microbiology from the United Nations Educational, Scientific and Cultural Organization (UNESCO). In 2000, Dr. López Charretón became an International Research Scholar with the Howard Hughes Medical Institute (HHMI) providing funding for the potentially transformative impact of her rotavirus research.
In 2010, HHMI asked López Charretón what she would do to change the world in one year. She responded, "I would invest that year in convincing people who make enormous amounts of money (TV and movie stars, singers, athletes, etc.) to donate just a small part of their earnings to make a well-administered foundation, with the sole purpose of ensuring that every child in underdeveloped countries has access to all available vaccines, independent of their cost, and to guarantee that these children are nourished properly during the first five years of their lives. This would help give a fair start in life to the people born in underdeveloped nations."
In 2012, López Charretón won the LÓréal-UNESCO Prize for Women in Science, a prestigious prize given to only one woman scientist per continent each year. López Charretón won the award for Latin America for "identifying how rotaviruses cause the death of 600,000 children each year." That same year, she was also awarded the Omecihuatl Medal from the Women's Institute of Mexico City. In 2013, López Charretón received the "Premio Universidad Nacional" for Natural Sciences research. And in 2014 she was recognized as one of the BBC's 100 women.
Personal life
She was a co-recipient (along her husband, Carlos Arias Ortiz) of both the 2001 Carlos J. Finlay Prize for Microbiology and the 2008 TWAS Prize in Biology. López Charretón and her husband have two children, Rodrigo and Alejandra. She lives in Mexico City.
References
External links
Profile at the Howard Hughes Medical Institute
Personal web page at the Institute of Biotechnology - UNAM (in Spanish)
Living people
Members of the Mexican Academy of Sciences
Mexican biochemists
Women biochemists
Mexican women chemists
Women virologists
National Autonomous University of Mexico alumni
Academic staff of the National Autonomous University of Mexico
Scientists from Mexico City
1957 births
L'Oréal-UNESCO Awards for Women in Science laureates
20th-century Mexican women scientists
21st-century Mexican women scientists
TWAS laureates
21st-century Mexican scientists
20th-century Mexican scientists | Susana López Charretón | [
"Chemistry"
] | 1,079 | [
"Biochemists",
"Women biochemists"
] |
14,522,331 | https://en.wikipedia.org/wiki/Oxoeicosanoid%20receptor%201 | Oxoeicosanoid receptor 1 (OXER1) also known as G-protein coupled receptor 170 (GPR170) is a protein that in humans is encoded by the OXER1 gene located on human chromosome 2p21; it is the principal receptor for the 5-Hydroxyicosatetraenoic acid family of carboxy fatty acid metabolites derived from arachidonic acid. The receptor has also been termed hGPCR48, HGPCR48, and R527 but OXER1 is now its preferred designation. OXER1 is a G protein-coupled receptor (GPCR) that is structurally related to the hydroxy-carboxylic acid (HCA) family of G protein-coupled receptors whose three members are HCA1 (GPR81), HCA2 (Niacin receptor 1), and HCA3 (Niacin receptor 2); OXER1 has 30.3%, 30.7%, and 30.7% amino acid sequence identity with these GPCRs, respectively. It is also related (30.4% amino acid sequence identity) to the recently defined receptor, GPR31, for the hydroxyl-carboxy fatty acid 12-HETE.
Species and tissue distribution
Orthologs of OXER1 are found in various mammalian species including opossums and several species of fish; however, mice and rats lack a clear ortholog of OXER1. This represents an important hindrance to studies on the function of OXER1 since these two mammalian species are the most common and easiest models for investigating the in vivo functions of receptors in mammals and by extrapolation humans. Since mouse cells make and respond to members of the 5-HETE family of agonists, it is most likely that mice do have a receptor that substitutes for OXER1 by mediating their responses to this agonist family. Recently, A G protein-couple receptor of the hydroxy carboxylic acid subfamily, Niacin receptor 1, has been proposed to mediate the responses of mouse tissues to 5-oxo-ETE.
OXER1 is highly expressed by human white blood cells, particularly eosinophils and to a lesser extent neutrophils, basophils, and monocytes; by bronchoalveolar macrophages isolated from human bronchoalveolar lavage washings; and by the human H295R adrenocortical cell line. Various types of human cancer cells lines express OXER1; these include those of the prostate, breast, lung, ovaries, colon, and pancreas. OXER1 is also expressed by the human spleen, lung, liver, and kidney tissues. The exact cell types bearing OXER1 in these tissues has not been defined.
A recent study has found that cats express the OXER1 receptor for 5-oxo-ETE, that feline leukocytes, including eosinophils, have been found to synthesize and be very highly responsive to 5-oxo-ETE, and that 5-oxo-ETE is present in the bronchoalveolar lavage fluid from cats with experimentally induced asthma; these findings suggest that the 5-oxo-ETE/OXER1 axis may play an important role in feline asthma, a common condition in this species, and that felines could serve as a useful animal model to investigate the pathophysiological role of 5-oxo-ETE in asthma and other conditions.
Ligands
The OXER1 G protein-coupled receptor resembles the hydroxy carboxilic acid subfamily of G protein-coupled receptors, which besides GPR109A, niacin receptor 1, and niacin receptor 2 may include the recently defined receptor for 12-HETE, GPR31, not only in its amino acid sequence but also in the hydroxy-carboxylic acid nature of its cognate ligands. Naturally occurring ligands for OXER1 are long chain polyunsaturated fatty acids containing either a hydroxyl (i.e. -OH) or oxo (i.e. =O, keto) residue removed by 5 carbons from each of these acid's carboxy residue.
Agonists
OXER1 is known or presumed to bind and thereby be activated by the following endogenous arachidonic acid metabolites; 5-oxo-ETE>5-oxo-15-hydroxy-ETE>5-hydroperoxyicosatetraenoic acid (5-HpETE)>5-HETE>5,20-diHETE. OXER1 is also activated by metabolites of other polyunsaturated fatty acids that therefore may be categorized as members of the 5-oxo-ETE family of agonists; these agonists include 5(S)-oxo-6E,8Z,11Z-eicosatrienoic acid (a 5-LO metabolite of mead acid); 5(S)-hydroxy-6E,8Z-octadecadienoic acid and 5(S)-oxo-6E,8Z-octadecadienoic acid (5-LO metabolites of sebaleic acid, i.e. 5Z,8Z-octadecadienoic acid); and 5(S)-hydroxy-6E,8Z,11Z,14Z,17Z-eicosapentaenoic and 5-oxo-6E,8Z,11Z,14Z,17Z-eicosapentaenoic acids (5-LO metabolites of the n-3 polyunsaturated fatty acid, eicosapentaenoic acid).
Antagonists
5-Oxo-12(S)-hydroxy-HETE and its 8-trans isomer, 5-oxo-12(S)-hydroxy-6E,8E,11Z,14Z-eicosatetraenoic acid, and a series of synthetic mimetics of 5-oxo-ETE structure (compounds 346, S-264, S-230, Gue154, and still to be named but considerably more potent drugs than these) block the activity of 5-oxo-ETE but not other stimuli in leukocytes and are presumed to be OXER1 antagonists.
Mechanisms of activating cells
OXE-R couples to the G protein complex Gαi-Gβγ; when bound to a 5-oxo-ETE family member, OXE-R triggers this G protein complex to dissociate into its Gαi and Gβγ components. Gβγ appears to be the component most responsible for activating many of the signal pathways that lead to cellular functional responses. Intracellular cell-activation pathways stimulated by OXER1 include those involving rises in cytosolic calcium ion levels, and along with others that lead to the activation of MAPK/ERK, p38 mitogen-activated protein kinases, cytosolic Phospholipase A2, PI3K/Akt, and protein kinase C beta (i.e. PRKCB1, delta (i.e. PRKCD), epsilon (i.e. PRKCE), and zeta (i.e. PRKCZ).
Function
OXER1 is activated by 5-oxo-ETE, 5-HETE, and other members of the 5-Hydroxyicosatetraenoic acid family of arachidonic acid metabolites and thereby mediates this family's stimulatory effects on
cell types that are involved in mediating immunity-based inflammatory reactions such as neutrophils, monocytes, and macrophages) as well as allergic reactions such as eosinophils and basophils. It also mediates the in vitro proliferation and other pro-malignant responses of cultured prostate, breast, ovary, and kidney cancer cells to the 5-HETE family of agonists. These studies suggest that OXER1 may be involved in orchestrating inflammatory and allergic responses in humans and contribute to the growth and spread of human prostate, breast, ovary, and kidney cancers. OXER1 is responsible for steroid production response to 5-oxo-ETE by human steroidogenic cells in vitro and therefore could be involved in steroid production in humans.
To date, however, all studies have been pre-clinical; they use model systems that can suggest but not prove the contribution of OXER1 to human physiology and diseases. The most well-studied and promising area for OXER1 function is in allergic reactions. The recent development of OXER1 antagonists will help address this issue.
See also
Eicosanoid receptor
5-Hydroxyicosatetraenoic acid and 5-oxo-eicosatetraenoic acid
Niacin receptor 1
References
Further reading
External links
G protein-coupled receptors | Oxoeicosanoid receptor 1 | [
"Chemistry"
] | 1,915 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,522,485 | https://en.wikipedia.org/wiki/Prostaglandin%20EP1%20receptor | {{DISPLAYTITLE:Prostaglandin EP1 receptor}}
Prostaglandin E2 receptor 1 (EP1) is a 42kDa prostaglandin receptor encoded by the PTGER1 gene. EP1 is one of four identified EP receptors, EP1, EP2, EP3, and EP4 which bind with and mediate cellular responses principally to prostaglandin E2) (PGE2) and also but generally with lesser affinity and responsiveness to certain other prostanoids (see Prostaglandin receptors). Animal model studies have implicated EP1 in various physiological and pathological responses. However, key differences in the distribution of EP1 between these test animals and humans as well as other complicating issues make it difficult to establish the function(s) of this receptor in human health and disease.
Gene
The PTGER1 gene is located on human chromosome 19 at position p13.12 (i.e. 19p13.12), contains 2 introns and 3 exons, and codes for a G protein-coupled receptor (GPCR) of the rhodopsin-like receptor family, Subfamily A14 (see rhodopsin-like receptors#Subfamily A14).
Expression
Studies in mice, rats, and guinea pigs have found EP1 Messenger RNA and protein to be expressed in the papillary collecting ducts of the kidney, in the kidney, lung, stomach, thalamus, and in the dorsal root ganglia neurons as well as several central nervous system sites. However, the expression of EP1 In humans, its expression appears to be more limited: EP1 receptors have been detected in human mast cells, pulmonary veins, keratinocytes, myometrium, and colon smooth muscle.
Ligands
Activating ligands
The following standard prostaglandins have the following relative potencies in binding to and activating EP1: PGE2≥PGE1>PGF2alpha>PGD2. The receptor binding affinity Dissociation constant Kd (i.e. ligand concentration needed to bind with 50% of available EP1 receptors) is ~20 nM and that of PGE1 ~40 for the mouse receptor and ~25 nM for PGE2 with the human receptor.
Because PGE2 activates multiple prostanoid receptors and has a short half-life in vivo due to its rapidly metabolism in cells by omega oxidation and beta oxidation], metabolically resistant EP1-selective activators are useful for the study of EP1's function and could be clinically useful for the treatment of certain diseases. Only one such agonist that is highly selective in stimulating EP1 has been synthesized and identified, ONO-D1-OO4. This compound has a Ki inhibitory binding value (see Biochemistry#Receptor/ligand binding affinity) of 150 nM compared to that of 25 nM for PGE2 and is therefore ~5 times weaker than PGE2.
Inhibiting ligands
SC51322 (Ki=13.8 nM), GW-848687 (Ki=8.6 nM), ONO-8711, SC-19220, SC-51089, and several other synthetic compounds given in next cited reference are selective competitive antagonists for EP1 that have been used for studies in animal models of human diseases. Carbacylin, 17-phenyltrinor PGE1, and several other tested compounds are dual EP1/EP3 antagonists (most marketed prostanoid receptor antagonists exhibit poor receptor selectivity).
Mechanism of cell activation
When initially bound to PGE2 or other stimulating ligand, EP1 mobilizes G proteins containing the Gq alpha subunit (Gαq/11)-G beta-gamma complex. These two subunits in turn stimulate the Phosphoinositide 3-kinase pathway that raises cellular cytosolic Ca2+ levels thereby regulating Ca2+-sensitive cell signal pathways which include, among several others, those that promote the activation of certain protein kinase C isoforms. Since, this rise in cytosolic Ca2+ can also contract muscle cells, EP1 has been classified as a contractile type of prostanoid receptor. The activation of protein kinases C feeds back to phosphorylate and thereby desensitizes the activated EP1 receptor (see homologous desensitization but may also desensitize other types of prostanoid and non-prostanoid receptors (see heterologous desensitization). These desensitizations limit further EP1 receptor activation within the cell. Concurrently with the mobilization of these pathways, ligand-activated EP1 stimulates ERK, p38 mitogen-activated protein kinases, and CREB pathways that lead to cellular functional responses.
Function
Studies using animals genetically engineered to lack EP1 and supplemented by studies using treatment with EP1 receptor antagonists and agonists indicate that this receptor serves several functions. 1) It mediates hyperalgesia due to EP11 receptors located in the central nervous system but suppresses pain perception due to E1 located on dorsal root ganglia neurons in rats. Thus, PGE2 causes increased pain perception when administered into the central nervous system but inhibits pain perception when administered systemically; 2) It promotes colon cancer development in Azoxymethane-induced and APC gene knockout mice. 3) It promotes hypertension in diabetic mice and spontaneously hypertensive rats. 4) It suppresses stress-induced impulsive behavior and social dysfunction in mice by suppressing the activation of Dopamine receptor D1 and Dopamine receptor D2 signaling. 5) It enhances the differentiation of uncommitted T cell lymphocytes to the Th1 cell phenotype and may thereby favor the development of inflammatory rather than allergic responses to immune stimulation in rodents. Studies with human cells indicate that EP1 serves a similar function on T cells. 6) It may reduce expression of Sodium-glucose transport proteins in the apical membrane or cells of the intestinal mucosa in rodents. 7) It may be differentially involved in etiology of acute brain injuries. Pharmacological inhibition or genetic deletion of EP1 receptor produce either beneficial or deleterious effects in rodent models of neurological disorders such as ischemic stroke, epileptic seizure, surgically induced brain injury and traumatic brain injury.
Clinical studies
EP1 receptor antagonists have been studied clinically primarily to treat hyperalgesia. Numerous EP antagonists have been developed including SC51332, GW-848687X, a benzofuran-containing drug that have had some efficacy in treating various hyperalgesic syndromes in animal models. None have as yet been reported to be useful in humans.
See also
Prostaglandin receptors
Prostanoid receptors
Prostaglandin E2 receptor 2 (EP2)
Prostaglandin E2 receptor 3 (EP3)
Prostaglandin E2 receptor 4 (EP4)
Eicosanoid receptor
References
Further reading
External links
G protein-coupled receptors | Prostaglandin EP1 receptor | [
"Chemistry"
] | 1,478 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,522,499 | https://en.wikipedia.org/wiki/Prostaglandin%20EP2%20receptor | {{DISPLAYTITLE:Prostaglandin EP2 receptor}}
Prostaglandin E2 receptor 2, also known as EP2, is a prostaglandin receptor for prostaglandin E2 (PGE2) encoded by the human gene PTGER2: it is one of four identified EP receptors, the others being EP1, EP3, and EP4, which bind with and mediate cellular responses to PGE2 and also, but with lesser affinity and responsiveness, certain other prostanoids (see Prostaglandin receptors). EP has been implicated in various physiological and pathological responses.
Gene
The PTGER2 gene is located on human chromosome 14 at position p22.1 (i.e. 14q22.1), contains 2 introns and 3 exons, and codes for a G protein coupled receptor (GPCR) of the rhodopsin-like receptor family, Subfamily A14 (see rhodopsin-like receptors#Subfamily A14).
Expression
EP2 is widely distributed in humans. Its protein is expressed in human small intestine, lung, media of arteries and arterioles of the kidney, thymus, uterus, brain cerebral cortex, brain striatum, brain hippocampus, corneal epithelium, corneal choriocapillaries, Myometriuml cells, eosinophiles, sclera of the eye, articular cartilage, the corpus cavernosum of the penis, and airway smooth muscle cells; its mRNA is expressed in gingival fibroblasts, monocyte-derived dendritic cells, aorta, corpus cavernosum of the penis, articular cartilage, airway smooth muscle, and airway epithelial cells. In rats, the receptor protein and/or mRNA has been found in lung, spleen, intestine, skin, kidney, liver, long bones, and rather extensively throughout the brain and other parts of the central nervous system.
EP2 expression in fibroblasts from the lungs of mice with bleomycin-induced pulmonary fibrosis and humans with Idiopathic pulmonary fibrosis is greatly reduced. In both instances, this reduced expression was associated with hypermethylation of CpG dinucleotide sites located in the first 420 base pairs upstream of the PTGER2 gene transcription start site of these fibroblasts. This suggests that EP2 expression is regulated by this methylation.
Ligands
Activating ligands
The following standard prostaglandins have the following relative efficacies in binding to and activating EP2: PGE2>PGF2alpha>=PGI2>PGD2. The receptor binding affinity Dissociation constant Kd (i.e. ligand concentration needed to bind with 50% of available EP1 receptors) is ~13 nM for PGE2 and ~10 nM for PGE1 with the human receptor and ~12 nM for PGE2 with the mouse receptor. Because PGE2 activates multiple prostanoid receptors and has a short half-life in vivo due to its rapidly metabolism in cells by omega oxidation and beta oxidation, metabolically resistant EP2-selective activators are useful for the study of this receptor's function and could be clinically useful for the treatment of certain diseases. There are several such agonists including butaprost free acid and ONO-AE1-259-01 which have Ki inhibitory binding values (see Biochemistry#Receptor/ligand binding affinity) of 32 and 1.8 NM, respectively, and therefore are respectively ~2.5-fold less and 7-fold more potent than PGE2.
Inhibiting ligands
PF-04418948 (Ki=16 nM), TG4-155 (Ki=9.9 nM), TG8-4, and TG6-129 are selective competitive antagonists for EP2 that have been used for studies in animal models of human diseases. Many of the earlier EP2 receptor antagonists used for such studies exhibited poor receptor selectivity, inhibiting, for example, other EP receptors.
Mechanism of cell activation
EP2 is classified as a relaxant type of prostanoid receptor based on its ability, upon activation, to relax certain types of smooth muscle (see Prostaglandin receptors). When initially bound to PGE2 or any other of its agonists, it mobilizes G proteins containing the Gs alpha subunit (i.e. Gαs)-G beta-gamma complexes (i.e. Gβγ). The Gαs- Gβγ complexes dissociate into their Gαs and Gβγ subunits which in turn regulate cell signaling pathways. In particular, Gαs stimulates adenylyl cyclase to raise cellular levels of cAMP thereby activating PKA; PKA activates various types of signaling molecules such as the transcription factor CREB which lead to different types of functional responses depending on cell type. EP2 also activates the a) GSK-3 pathway which regulates cell migratory responses and innate immune responses including pro-inflammatory cytokine and interleukin production and b) Beta-catenin pathway which regulates not only cell–cell adhesion but also activates the Wnt signaling pathway which, in turn, stimulates the transcription of genes responsible for regulating cell migration and proliferation. In many of these respects, EP2 actions resemble those of another type of relaxant prostanoid receptor, EP4 but differs from the contractile prostanoid receptors, EP1 and EP3 receptors which mobilize G proteins containing the Gαq-Gβγ complex. EP2 also differs from all the other prostaglandin receptors in that it fails to undergo homologous desensitization. That is, following agonist-induced activation, the other prostaglandin (as well as most types of G protein coupled receptors) quickly become desensitized, often internalized, and whether or not internalized, incapable of activating their G protein targets. This effect limits the duration and extent to which agonists can stimulate cells. EP2, by failing to become desensitized, is able to function over prolong periods and later time points than other prostaglandin receptors and therefore potentially able to contribute to more delayed and chronic phases of cellular and tissue responses.
Functions
Studies using animals genetically engineered to lack EP2 and supplemented by studies examining the actions of EP2 receptor antagonists and agonists in animals as well as animal and human tissues indicate that this receptor serves various functions.
Eye
When applied topically into the eyes of rodents, cats, rhesus monkeys, and humans PGE2 acts, apparently acting at least in part through EP2, decreases intraocular pressure by stimulating increases in the drainage of aqueous humor through the uveoskceral pathway, the principal aqueous humor outflow pathway in the eye.
Reproduction
Female mice engineered to lack a functional Pgter2 gene show a modest reduction in ovulation and more severely impaired capacity for Fertilisation. Studies suggest that this impaired fertilization reflects the loss of EP2 functions in stimulating cumulus cells clusters which surround oocytes to: a) form the CCL7 chemokine which serves as a chemoattractant that guides sperm cells to oocytes and b) disassemble the extracellular matrix which in turn allows sperm cells to penetrate to the oocyte. These data allow that an EP2 receptor antagonist may be a suitable candidate as a contraceptive for women.
Inflammation and allergy
Activation of EP2 contributes to regulating B cell immunoglobulin class switching, maturation of T lymphocyte CD4−CD8− cells to CD4+CD8+ cells, and the function of Antigen-presenting cells, particularly Dendritic cells. EP thereby contributes to the development of inflammation in rodent models of certain types of experimentally-induced joint and paw inflammation and the neurotoxic effects of endotoxin. However, EP2 activation also has anti-inflammatory actions on pro-inflammatory cells (e.g. neutrophils, monocytes, macrophages, dendritic cells, NK cells, TH1 cells, TH2 cells, and fibroblasts in various tissues and on microglia cells in the central nervous system). These actions suppress certain forms of inflammation such NMDA receptor-related neurotoxicity and the rodent model of Bleomycin-induced pulmonary fibrosis. EP2 activation also inhibits the phagocytosis and killing of pathogens by alveolar macrophages; these effects may serve an anti-inflammatory role but reduce host defense against these pathogens.
Activation of EP2 also influences allergic inflammatory reactions. It dilates airways (bronchodilation) contracted by the allergic mediator, histamine; inhibits Immunoglobulin E-activated mast cells from releasing histamine and leukotrienes (viz., LTC4, LTD4, and LTE4), all of which have bronchoconstricting and otherwise pro-allergic actions; inhibits pro-allergic eosinophil apoptosis, chemotaxis, and release of pro-allergic granule contents; and reduces release of the pro-allergic cytokines Interleukin 5, Interleukin 4, and interleukin 13 from human blood mononuclear cells.
Cardiovascular
EP2 receptor-deficient mice develop mild systolic and/or systemic hypertension which is worsened by high dietary intake of salt. These effects are thought to be due to the loss of EP2's vasodilation effects and/or ability to increase the urinary excretion of salt.
Bone
EP2-deficient mice exhibit impaired generation of osteoclasts (cells that break down bone tissue) due to a loss in the capacity of osteoblastic cells to stimulate osteoclast formation. These mice have weakened bones compared with the wild type animals. When administered locally or systemically to animals, EP2-selective agonists stimulate the local or systemic formation of bone, augment bone mass, and accelerate the healing of fractures and other bone defects in animal models.
Nervous system
EP2 deficient mice exhibit reduced Oxidative stress and beta amyloid formation. Activation of this receptor also has neuroprotective effects in models of Alzheimer's disease, Amyotrophic lateral sclerosis, multiple sclerosis, and stroke while its inhibition reduces Epileptic seizure. EP2 signaling can also increase stroke injury via neurons in a mice model according to a PNAS paper. EP2 receptors on either nerve or Neuroglia cells of the peripheral and central nervous system act to promote pain perception, which are caused by inflammation, muscle stretch, temperature, and physical stimuli (see allodynia) in mice. A 2021 study found that inhibition of myeloid cell EP2 signalling can reverse or prevent an inflammation element of brain-ageing in mice.
Malignancy
The EP2 receptor can act as a tumor promoter. EP2 gene knockout mice have less lung, breast, skin, and colon cancers following exposure to carcinogens. Knockout of this gene in mice with the adenomatous polyposis coli mutation also causes a decrease in the size and number of pre-cancerous intestinal polyps that the animals develop. These effects are commonly ascribed to the loss of EP2-mediated: Vascular endothelial growth factor production and thereby of tumor vascularization; regulation of endothelial cell motility and survival; interference with transforming growth factor-β's anti-cell proliferation activity; and, more recently, regulation of host anti-tumor immune responses.
Clinical significance
Therapeutics
Preclinical studies, as outlined above, indicate that EP2 may be a target for treating and/or preventing particular human disorders involving: allergic diseases such as asthma and rhinitis, particularly aspirin-exacerbated respiratory disease (AERD); glaucoma; various diseases of the nervous system; fractures, osteoporosis, and other bone abnormalities; pulmonary fibrosis; certain forms of malignant disease such as colon cancer including those that arise from Adenomatous polyposis coli mutations; and salt-sensitive forms of hypertension; This receptor has also been suggested to be a target for contraception. To date, however, there has been little translational research to determine the possible beneficial effects of EP2 antagonists or agonists in humans. The following drugs that act on EP2 but also other prostaglandin receptors are in clinical use:
Iloprost activates EP2, EP3, and EP4 receptors to treat diseases involving pathological constriction of blood vessels such as pulmonary hypertension, Raynauds disease, and scleroderma. Presumably, it works by stimulating EP2, and EP4 receptors which have vasodilation actions.
Misoprostol, an EP3 and EP4 receptor agonist, to prevent ulcers; to induce labor in pregnancy, medical abortion, and late miscarriage; and to prevent and treat postpartum bleeding.
The following drugs are in development or proposed to be candidates for development as highly selective EP2 agonists for the indicated conditions:
Butaprost for the treatment of pulmonary fibrosis and certain neurological diseases
CP533,536 for the stimulation of bone formation
Taprenepag isopropyl (PF-04217329) for the treatment of glaucoma and various neurological diseases (see above section on Nervous system)
Genomic studies
The single-nucleotide polymorphism (SNP) variant rs17197 in the 3' untranslated region of PTGER2 has been associated with an increased incidence of essential hypertension in a population of Japanese men. SNP variant rs1254598 in a Spanish population; SNP variant uS5 located in a STAT-binding consensus sequence of the regulatory region of PTGER2 with reduced transcription activity in a Japanese population; and two PTGER2 SNP variants (-616C>G and -166G>A) in a Korean population have been associated with an increased incidence of Aspirin-induced asthma.
See also
Prostanoid receptors
Prostaglandin receptors
Prostaglandin E2 receptor 1 (EP1)
Prostaglandin E2 receptor 3 (EP3)
Prostaglandin E2 receptor 4 (EP4)
Eicosanoid receptor
References
Further reading
External links
G protein-coupled receptors | Prostaglandin EP2 receptor | [
"Chemistry"
] | 3,063 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,522,546 | https://en.wikipedia.org/wiki/Prostaglandin%20EP3%20receptor | {{DISPLAYTITLE:Prostaglandin EP3 receptor}}
Prostaglandin EP3 receptor (EP3, 53kDa), is a prostaglandin receptor for prostaglandin E2 (PGE2) encoded by the human gene PTGER3; it is one of four identified EP receptors, the others being EP1, EP2, and EP4, all of which bind with and mediate cellular responses to PGE2 and also, but generally with lesser affinity and responsiveness, certain other prostanoids (see Prostaglandin receptors). EP has been implicated in various physiological and pathological responses.
Gene
The PTGER3 gene is located on human chromosome 1 at position p31.1 (i.e. 1p31.1), contains 10 exons, and codes for a G protein coupled receptor (GPCR) of the rhodopsin-like receptor family, Subfamily A14 (see rhodopsin-like receptors#Subfamily A14). PTGER3 codes for at least 8 different isoforms in humans, i.e. PTGER3-1 to PGGER3-8 (i.e., EP3-1, EP3-2, EP3-3, EP3-4, EP3-5, EP3-6, EP3-7, and EP3-8), while Ptger3 codes for at least 3 isoforms in mice, Ptger1-Ptger3 (i.e. Ep3-α, Ep3-β, and Ep3-γ). These isoforms are variants made by Alternative splicing conducted at the 5'-end of DNA to form proteins that vary at or near their C-terminus. Since these isoforms different in their tissue expressions as well as the signaling pathways which they activate, they may vary in the functions that they perform. Further studies are needed to examine functional differences among these isoforms.
Expression
EP3 is widely distributed in humans. Its protein and/or mRNA is expressed in kidney (i.e. glomeruli, Tamm-Horsfall protein negative late distal convoluted tubules, connecting segments, cortical and medullary collecting ducts, media and endothelial cells of arteries and arterioles); stomach (vascular smooth muscle and gastric fundus mucosal cells); thalamus (anterior, ventromedial, laterodorsal, paraventricular and central medial nuclei); intestinal mucosal epithelia at the apex of crypts; myometrium (stromal cells, endothelial cells, and, in pregnancy, placenta, chorion, and amnion); mouth gingival fibroblasts; and eye (corneal endothelium and keratocytes, trabecular cells, ciliary epithelium, and conjunctival and iridal stroma cells, and retinal Müller cells).
Ligands
Activating ligands
Standard prostanoids have the following relative efficacies in binding to and activating EP3: PGE2>PGF2α=PGI2>PGD2=TXA2. Prostglandin E1 (PGE1), which has one less double bond than PGE2, has the same binding affinity and potency for EP3 as PGE2. PGE2 has extreme high affinity (dissociation constant Kd=0.3 nM) for EP3. Several synthetic compounds, e.g. sulprostone, SC-46275, MB-28767, and ONO-AE-248, bind to and stimulate with high potency EP3 but unlike PGE2 have the advantage of being highly selective for this receptor over other EP receptors and are relatively resistant to being metabolically degraded. They are in development as drugs for the potential treatment of stomach ulcers in humans.
Inhibiting ligands
Numerous synthetic compounds have been found to be highly selective in binding to but not stimulating EP3. These Receptor antagonist DG-O41, L798,106, and ONO-AE3-240, block EP3 from responding to PGE2 or other agonists of this receptor, including Sulprostone, ONO-AE-248 and TEI-3356. They are in development primarily as anti-thrombotics, i.e. drugs to treat pathological blood clotting in humans.
Mechanism of cell activation
EP3 is classified as an inhibitory type of prostanoid receptor based on its ability, upon activation, to inhibit the activation of adenylyl cyclase stimulated by relaxant types of prostanoid receptors viz., prostaglandin DP, E2, and E4 receptors (see Prostaglandin receptors). When initially bound to PGE2 or other of its agonists, it mobilizes G proteins containing various types of G proteins, depending upon the particular EP3 isoform: EP3α and EP3β isoforms activate Gi alpha subunit (i.e. Gαi)-G beta-gamma complexes (i.e. Gαi)-Gβγ) complexes) as well as Gα12-Gβγ complexes while the EP3γ isoform activates in addition to and the Gαi- Gβγ complexes Gαi- Gβγ complexes. (G protein linkages for the other EP3 isoforms have not been defined.) In consequence, complexes dissociate into Gαi, Gα12, Gs and Gβγ components which proceed to activate cell signaling pathways that lead functional responses viz., pathways that activate phospholipase C to convert cellular phospholipids to diacylglycerol which promotes the activation of certain isoforms of protein kinase C, pathways that elevated cellular cytosolic Ca2+ which thereby regulate Ca2+-sensitive cell signaling molecules, and pathways that inhibit adenylyl cyclase which thereby lowers cellular levels of cyclic adenosine monophosphate (cAMP) to reduce the activity of cAMP-dependent signaling molecules.
Functions
Studies using animals genetically engineered to lack EP3 and supplemented by studies examining the actions of EP3 receptor antagonists and agonists in animals as well as animal and human tissues indicate that this receptor serves various functions. However, an EP3 receptor function found in these studies does not necessarily indicate that in does do in humans. For example, EP3 receptor activation promotes duodenal secretion in mice; this function is mediated by EP4 receptor activation in humans. EP receptor functions can vary with species and most of the functional studies cited here have not translated their animal and tissue models to humans.
Digestive system
The secretion of (bicarbonate anion) from Brunner's glands of the duodenum serves to neutralize the highly acidified digestive products released from the stomach and thereby prevents ulcerative damage to the small intestine. Activation of EP3 and EP4 receptors in mice stimulates this secretion but in humans activation of EP4, not EP3, appears responsible for this secretion. These two prostanoid receptors also stimulate intestinal mucous secretion, a function which may also act to reduce acidic damage to the duodenum.
Fever
EP3-deficient mice as well as mice selectively deleted of EP3 expression in the brain's median preoptic nucleus fail to develop fever in response to endotoxins (i.e. bacteria-derived lipopolysaccharide) or the host-derived regulator of body temperature, IL-1β. The ability of endotoxins and IL-1β but not that of PGE2 to trigger fever is blocked by inhibitors of nitric oxide and PG2. EP3-deficient mice exhibit normal febrile responses to stress, interleukin-8, and macrophage inflammatory protein-1beta (MIP-1β). It is suggested that these findings indicate that a) activation of the EP3 receptor suppresses the inhibitory tone that the preoptic hypothalamus has on thermogenic effector cells in the brain; b) endotoxin and IL-1β simulate the production of nitric oxide which in turn causes the production of PGE2 and thereby the EP3-dependent fever-producing; c) other factors such as stress, interleukin 8, and MIP-1β trigger fever independently of EP3; and d) inhibition of the PGE2-EP3 pathway underlies the ability of aspirin and other Nonsteroidal anti-inflammatory drugs to reduce fever caused by inflammation in animals and, possibly, humans.
Allergy
In a mouse model of ovalbumin-induced asthma, a selective EP3 agonist reduced airway cellularity, mucus, and bronchoconstriction responses to methacholine. In this model, EP3-deficient mice, upon ovalbumin challenge, exhibited worsened allergic inflammation as measured by increased airway eosinophils, neutrophils, lymphocytes, and pro-allergic cytokines (i.e. interleukin 4, interleukin 5, and interleukin 13) as compared to wild type mice. EP3 receptor-deficient mice and/or wild type mice treated with an EP3 receptor agonist are similarly protected from allergic responses in models of allergic conjunctivitis and contact hypersensitivity. Thus, EP3 appears to serve an important role in reducing allergic reactivity at least in mice.
Cough
Studies with mice, guinea pig, and human tissues and in guinea pigs indicate that PGE2 operates through EP3 to trigger cough responses. Its mechanism of action involves activation and/or sensitization of TRPV1 (as well as TRPA1) receptors, presumably by an indirect mechanism. Genetic polymorphism in the EP3 receptor (rs11209716), has been associated with ACE inhibitor-induce cough in humans. The use of EP3 receptor antagonists may warrant study for the treatment of chronic cough in humans.
Blood pressure
Activation of EP3 receptors contracts vascular beds including rat mesentery artery, rat tail artery, guinea-pig aorta, rodent and human pulmonary artery, and murine renal and brain vasculature. Mice depleted of EP3 are partially protected from brain injury consequential to experimentally induced cerebral ischemia. Furthermore, rodent studies indicate that agonist-induced activation of EP3 in the brain by intra-cerebroventricular injection of PGE2 or selective EP3 agonist cause hypertension; a highly selective EP3 receptor antagonist blocked this PGE2-induced response. These studies, which examine a sympatho-excitatory response (i.e. responses wherein brain excitation such as stroke raises blood pressure) suggest that certain hypertension responses in humans are mediated, at least in part, by EP3.
Vascular permeability
Model studies indicate that PG2 (but not specific antigens or IgE cross-linkage) stimulates mouse and human mast cells to release histamine by an EP3-dependent mechanism. Furthermore, EP3-deficient mice fail to develop increased capillary permeability and tissue swelling in response to EP3 receptor agonists and the metabolic precursor to PGE2, arachidonic acid. It is suggested, based on these and other less direct studies, that PGE2-EP3 signaling may be responsible for the skin swelling and edema provoked by topical 5-aminolaevulinic acid photodynamic therapy, contact with chemical irritants, infection with pathogens, and various skin disorders in humans.
Blood clotting
Activation of EP3 receptors on the blood platelets of mice, monkeys, and humans enhances their aggregation, degranulation, and blood clot-promoting responsiveness to a wide array of physiological (e.g. thrombin) and pathological (e.g. atheromatous plaques. (In contrast, activation of either the EP2 or EP3 receptor inhibits platelet activation) Inhibition of EP3 with the selective EP3 receptor antagonist, DG-041, has been shown to prevent blood clotting but not to alter hemostasis or blood loss in mice and in inhibit platelet activation responses in human whole blood while not prolonging bleeding times when given to human volunteers. The drug has been proposed to be of potential clinical use for the prevention of blood clotting while causing little or no bleeding tendencies.
Pain
EP3 deficient mice exhibit significant reductions in: hyperalgesic writhing (i.e. squirming) responses to acetic acid administration; acute but not chronic Herpes simplex infection-induced pain; and HIV-1 Envelope glycoprotein GP120 intrathecal injection-induced tactile allodynia. Furthermore, a selective EP3 agonist, ONO-AE-248, induces hyperalgesia pain in wild type but not EP3-deficient mice. While pain perception is a complex phenomenon involving multiple causes and multiple receptors including EP2, EP1, LTB4, bradykinin, nerve growth factor, and other receptors, these studies indicate that EP3 receptors contribute to the perception of at least certain types of pain in mice and may also do so in humans.
Cancer
Studies of the direct effects of EP3 receptor activation on cancer in animal and tissue models give contradictory results suggesting that this receptor does not play an important role in Carcinogenesis. However, some studies suggest an indirect pro-carcinogenic function for the EP3 receptor: The growth and metastasis of implanted Lewis lung carcinoma cells, a mouse lung cancer cell line, is suppressed in EP3 receptor deficient mice. This effect was associated with a reduction in the levels of Vascular endothelial growth factor and matrix metalloproteinase-9 expression in the tumor's stroma; expression of the pro-lymphangiogenic growth factor VEGF-C and its receptor, VEGFR3; and a tumor-associated angiogenesis and lymphangiogenesis.
Clinical significance
Therapeutics
Many drugs that act on EP3 and, often, other prostaglandin receptors, are in clinical use. A partial list of these includes:
Misoprostol, an EP3 and EP4 receptor agonist, is in clinical use to prevent ulcers, to induce labor in pregnancy, medical abortion, and late miscarriage, and to prevent and treat postpartum bleeding (see Misoprostol).
Sulprostone, relatively selective EP3 receptor agonist with a weak ability to stimulate the EP1 receptor is in clinical use for inducing medical abortion and ending pregnancy after fetal death (see Sulprostone).
Iloprost activates EP2, EP3, and EP4 receptors; it is in clinical use to treat diseases involving pathological constriction of blood vessels such as pulmonary hypertension, Raynauds disease, and scleroderma. Presumably, Iloprost works by stimulating EP2, and EP4 receptors which have vasodilation actions.
Other drugs are in various stages of clinical development or have been proposed to be tested for clinical development. A sampling of these includes:
Enprostil, which binds to and activates primarily the EP3 receptor, was found in a prospective multicenter randomized controlled trial conducted in Japan to significantly improve the effects of cimetidine in treating gastric ulcer. It is considered to be an efficient and safe treatment for gastric and duodenal ulcers.
ONO-9054 (Sepetoprost), a dual an EP3/Prostaglandin F receptor agonist, is in phase 1 clinical trial studies for the treatment of ocular hypertension and open-angle glaucoma.
DG-041, a highly selective EP3 antagonist, has been proposed to warrant further study as anti-thrombosis agent.
GR 63799X, MB-28767, ONO-AE-248, and TEI-3356 are putative EP3 receptor-selective agonists that have been proposed to warrant further study to treat and/or prevent various types of cardiovascular diseases.
Genomic studies
The single nucleotide polymorphism (SNP) in the PTGER3, rs977214 A/G variant has been associated with an increase in pre-term births in two populations of European ancestry; the SNP variant -1709T>A in PTGER3 has been associated with aspirin-exacerbated respiratory disease in a Korean population; and 6 SNP variants have been associated with development of the Steven Johnson syndrome and its more severe form, toxic epidermal necrolysis, in a Japanese population.
See also
Eicosanoid receptor
Prostaglandin E2 receptor 1 (EP1)
Prostaglandin E2 receptor 2 (EP2)
Prostaglandin E2 receptor 4 (EP4)
References
Further reading
External links
G protein-coupled receptors | Prostaglandin EP3 receptor | [
"Chemistry"
] | 3,598 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,522,570 | https://en.wikipedia.org/wiki/Prostaglandin%20F%20receptor | Prostaglandin F receptor (FP) is a receptor belonging to the prostaglandin (PG) group of receptors. FP binds to and mediates the biological actions of prostaglandin F2α (PGF2α). It is encoded in humans by the PTGFR gene.
Gene
The PTGFR gene is located on human chromosome 1 at position p31.1 (i.e. 1p31.1), contains 7 exons, and codes for a G protein coupled receptor (GPCR) of the rhodopsin-like receptor family, Subfamily A14 (see rhodopsin-like receptors#Subfamily A14). PTGFR is expressed as two alternatively spliced transcript variants encoding different isoforms, FPA and FPB, which have different C-terminal lengths. MicroRNA miR-590-3p binds to the Three prime untranslated region of the FP gene to repress its translation. miR-590-3p thus appears to be a negative regulator of FP expression in various cell types.
Expression
In humans, FP mRNA and/or protein is highly expressed in the uterine myometrium; throughout the eye (endothelium and smooth muscle cells of blood vessels of the iris), ciliary body and choroid plexus; ciliary muscle (circular muscle, collagenous connective tissues; sclera; and ovarian (follicles and corpus luteum). Studies in mice indicate that FP mRNA and/or protein is expressed in diverse tissues including the kidney (distal tubules), uterus, and ovary (Luteal cells of corpus luteum.
Ligands
Activating ligands
The FP receptor is the least selective of the prostenoid receptors in that it is responsive to PGD2 and to a lesser extent PGE2 at concentrations close to those of PGF2α. Standard prostanoids have the following relative efficacies as receptor ligands in binding to and activating FP: PGF2α>PGD2>PGE2>PGI2=TXA2. In typical binding studies, PGF2α has one-half maximal binding and cell stimulating actions at ~1 nanomolar whereas PGD2 and PGE2 are ~5- to 10-fold and 10-100-fold weaker than this. The synthetic analogs that like PGF2α act as selective receptor agonists of FP viz., cloprostenol, flupostenol, latanoprost, and tafluprost (acid form) have FP binding affinities and stimulating potencies similar to PGF2α while others as enprostil, sulprostone, U46619, carbacyclin, and iloprost are considerably weaker FP agonists. Fluprostenol is a widely used clinically as a selective FP receptor agonist; latanoprost is a suitable substitute.
Inhibiting ligands
Currently, there are no selective receptor antagonists for FP.
Mechanism of cell activation
FP is classified as a contractile type of prostenoid receptor based on its ability, upon activation, to contract certain smooth muscle preparations and smooth muscle-containing tissues such as those of the uterus. When bound to PGF2α or other of its agonists, FP mobilizes primarily G proteins containing the Gq alpha subunit bound to of the Gq-Gβγ complex(i.e. Gqβγ). Gqβγ then dissociate into its Gq and Gβγ components which act to regulate cell signaling pathways. In particular, Gq stimulates cell signal pathways involving a) phospholipase C/IP3/cell Ca2+ mobilization/diacylglycerol/protein kinase Cs; calmodulin-modulated myosin light chain kinase; RAF/MEK/Mitogen-activated protein kinases; PKC/Ca2+/Calcineurin/Nuclear factor of activated T-cells; and the EGF cellular receptor. In certain cells, activation of FP also stimulates G12/G13-Gβγ G proteins to activate the Rho family of GTPases signaling proteins and Gi-Gβγ G proteins to activateRaf/MEK/mitogen-activated kinase pathways.
Functions
Studies using animals genetically engineered to lack FP and examining the actions of EP4 receptor agonists in animals as well as animal and human tissues indicate that this receptor serves various functions. It has been regarded as the most successful therapeutic target among the 9 prostanoid receptors.
Eye
Animal and human studies have found that the stimulation of FP receptors located on Ciliary muscle and trabecular meshwork cells of the eye widens the drainage channels (termed the uveoscleral pathway) that they form. This increases the outflow of aqueous humor from the anterior chamber of the eye through Schlemm's canal to outside of the eyeball. The increase in aqueous humor outflow triggered by FP receptor activation reduces Intraocular pressure and underlies the widespread usage of FP receptor agonists to treat glaucoma. László Z. Bitó is credited with making critical studies to define this intraocular pressure-relieving pathway. Three FP receptor agonists are approved for clinical use in the USA viz., travoprost, latanoprost, and bimatoprost, and two additional agonists are prescribed in Europe and Asia viz., unoprostone and tafluprost.
Hair growth
Since FP receptors are expresses in human dermal papillae and the use of FP agonists to treat glaucoma has as a side-effect an increase in eyelash growth, it has been suggested that FP agonists may be useful for treating baldness. This is supported by studies in the stump-tailed Macaque primate model of androgen-induced scalp alopecia which have found that the FP agonist, latanoprost, promotes scalp hair growth. These studies have not yet been translated into baldness therapy in humans.
Reproduction
FP receptor activation contributes to the regression of the corpus luteum and thereby the estrous cycle in many species of farm animals. However, it does not make these contributions in mice and its contribution to these functions in humans is controversial. The receptor has been in use as a target for decades to regulate the estrous cycle as well as to induce labor in pregnant farm animals FP gene knockout in female mice blocks parturition. That is, these FP-/- mice fail to enter labor even if induced by oxytocin due to a failure in copus luteum regression and consequential failure to stop secreting progesterone (declining progesterone levels trigger labor). Studies with monkey and human tissues allow that FP receptors may have a similar function in humans.
Skin pigmentation
One side effect of applying FP receptor agonists to eyelashes in humans is the development of hyperpigmentation at nearby skin sites. Follow-up studies of this side effect indicated than human skin pigment-forming melanocyte cells express FP receptors and respond to FP receptor agonists by increasing their dendricites (projections to other cells) as well as to increase their tyrosinase activity. Since skin melanocytes use their dendrites to transfer the skin pigment melanin to skin keratinocytes thereby darkening skin and since tyrosinase is the rate-limiting enzyme in the synthesis of melanin, these studies suggest that FP receptor activation may be a useful means to increase skin pigmentation.
Bone
PGF2α triggers the NFATC2 pathway stimulating skeletal muscle cell growth. PGF2α, shown or presumed to operate by activating FP receptors, has complex effects on bone osteoclasts and osteoblasts to regulate bone remodeling. However, further studies on the impact of the PGF2α-FP axis on bone are needed to better understand the pathophysiology underlying bone turnover and to identify this axis as a novel pharmacological target for the treatment of bone disorders and diseases.
Inflammation and allergy
Unlike other prostaglandin receptors which have been shown in numerous studies to contribute to inflammatory and allergic responses in animal models, there are few studies on the function of FP receptors in these responses. Gene knockout studies in mice clearly show that FP mediates the late phase (thromboxane receptor mediates the early phase) of the tachycardia response to the pro-inflammatory agent, lipopolysaccharide. PTGFR knockout mice also show a reduction in the development of pulmonary fibrosis normally caused by microbial invasion or bleomycin treatment. Finally, administration of PGF2α to mice causes an acute inflammatory response and elevated biosynthesis of PGF2α has been found in the tissues of patients with rheumatoid arthritis, psoriatic arthritis, and other forms of arthritis. While much further work is needed, these studies indicate that PGF2α-FP axis has some pro-inflammatory and anti-inflammatory effects in animals that may translate to humans. The axis may likewise play role in human allergic responses: PGF2α causes airway constriction in normal and asthmatic humans and its presence in human sputum is related to sputum eosinophil levels.
Cardiovascular system
PGF2α simulates an increase in systolic blood pressure in wild type but not FP(−/−) mice. Furthermore, FP(-/-) mice have significantly lower blood pressure, lower plasma renin levels, and lower plasma angiotensin-1 levels than wild-type mice, and FP agonists have a negative inotropic effect to weaken the strength of heart beating in rats. Finally, FP(−/−) mice deficient in the LDL receptor exhibit significantly less atherosclerosis than FP(+/+) LDL receptor-deficient mice. Activation of FP thus has pathophysiological consequences for the cardiovascular system relative to blood pressure, cardiac function, and atherosclerosis in animal models. The mechanism behind these FP effects and their relevancy to humans have not been elucidated.
Clinical significance
Therapeutic
Glaucoma
FP receptor agonists, specifically latanoprost, travoprost, bimatoprost, and tafluprost, are currently used as first-line drugs to treat glaucoma and other causes of intra-ocular hypertension (see Glaucoma#Medication).
Hair growth
The FP receptor agonist, bimatoprost, in the form of an 0.03% ophthalmic solution termed Latisse, is approved by the US Food and Drug Administration to treat hypotrichosis of the eyelashes, in particular to darken and lengthen eyelashes for cosmetic purposes. Eyelid hypotrichosis caused by
Veterinary uses
FP receptor agonists are used as highly effective agents to synchronize the oestrus cycles of farm animals and thereby to facilitate animal husbandry.
Translational studies
Hair growth
Eyelash hypotrichosis due to the autoimmune disease alopecia areata, or to chemotherapy, have been successfully treated with FP agonists in small translational research studies. In a randomized, double-blind, placebo-controlled pilot study of 16 men with male pattern baldness (also termed androgenetic alopecia) topical application of the FP agonist, latanoprost, for 24 weeks produced a significant increase in scalp hair density. Despite these findings, however, a case report of one woman with female pattern hair loss found that injection of FP agonist bimatoprost failed to influence hair growth.
Skin pigmentation
In preliminary studies, three Korean patients with periorbital vitiligo (i.e. skin blanching) were treated topically with the FP receptor agonist, latanoprost, for two months; the three patients experienced 20%, 50%, and >90% re-pigmentation of their vitiligo lesions. Fourteen patients with hypopigmented in their scarreed tissues were treated with the FP receptor agonist, bimatoprost, applied topically plus laser therapy and topical tretinoin or pimecrolimus. Most patients demonstrated significant improvement in their hypopigmentation, but the isolated effect of topical bimatoprost was not evaluated. These studies allow that FP receptor agonists may be useful for treating hypopigmentation such as occurs in scar tissue as well as diseases like vitiligo, tinea versicolor, and pityriasis alba.
Genomic studies
The single-nucleotide polymorphism (SNP) A/G variant, rs12731181, located in the Three prime untranslated region of PTGFR has been associated with increased risk for hypertension in individuals from southern Germany; while this association was not replicated in other European populations, it was found in a Korean population. This SNP variant reduces the binging of MicroRNA miR-590-3p to PTGFR; since this binding represses translation of this gene, the rs127231181 variant acts to increase expression of the FP receptor. PTGFR SNP variants rs6686438 and rs10786455s were associated with positive and SNP variants rs3753380, rs6672484, and rs11578155 in PTGFR were associated with negative responses to latanoprost for the treatment of Open-Angle Glaucoma in a Spanish population. PTGFR SNP variants rs3753380 and rs3766355 were associated with a reduce response to latanoprost in a Chinese population study.
See also
Prostaglandin F2 alpha
Prostaglandin receptors
Eicosanoid receptor
References
External links
Further reading
G protein-coupled receptors | Prostaglandin F receptor | [
"Chemistry"
] | 3,004 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,522,621 | https://en.wikipedia.org/wiki/Prostacyclin%20receptor | The prostacyclin receptor, also termed the prostaglandin I2 receptor or just IP, is a receptor belonging to the prostaglandin (PG) group of receptors. IP binds to and mediates the biological actions of prostacyclin (also termed prostaglandin I2, PGI2, or when used as a drug, epoprostenol). IP is encoded in humans by the PTGIR gene. While possessing many functions as defined in animal model studies, the major clinical relevancy of IP is as a powerful vasodilator: stimulators of IP are used to treat severe and even life-threatening diseases involving pathological vasoconstriction.
Gene
The gene is located on human chromosome 19 at position q13.32 (i.e. 19q13.32), contains 6 exons, and codes for a G protein coupled receptor (GPCR) of the rhodopsin-like receptor family, Subfamily A14 (see rhodopsin-like receptors#Subfamily A14).
Expression
IP is most highly expressed in brain and thymus and is readily detected in most other tissues. It is found throughout the vascular network on endothelium and smooth muscle cells.
Ligands
Agonists
Standard prostanoids have the following relative efficacies as receptor ligands in binding to and activating IP: PGI2>>PGD2=PGE2=PGF2α>TXA2. In typical binding studies, PGI2 has one-half of its maximal binding capacity and cell-stimulating actions at ~1 nanomolar whereas the other prostaglandins are >50-fold to 100-fold weaker than this. However, PGI2 is very unstable, spontaneously converting to a far less active derivative 6-keto-PGF1 alpha within 1 minute of its formation. This instability makes defining the exact affinity of PGI2 for IP difficult. It also makes it important to have stable synthetic analogs of PGI2 for clinical usage. The most potent of these receptor agonists for binding to and activating IP are iloprost, taprostene, and esuberaprost which have Kd values (i.e. concentrations which bind to half of available IP receptors) in the low nanomole/liter range.
Antagonists
Several synthetic compounds bind to, but do not activate, IP and thereby inhibit its activation by the activating ligands just described. These receptor antagonists include RO1138452, RO3244794, TG6-129, and BAY-73-1449, all of which have Kd values for IP at or beneath low nanomol/liter levels.
Mechanism of cell activation
IP is classified as a relaxant type of prostenoid receptor based on its ability, upon activation, to relax certain pre-contracted smooth muscle preparations and smooth muscle-containing tissues such as those of pulmonary arteries and veins. When bound to PGI2 or other of its agonists, IP stimulates one or more of three types of G protein complexes, depending on cell type: a) Gs alpha subunit-Gβγ complexes which release Gs that then stimulates adenyl cyclase to raise intracellular levels of cAMP and thereby activate cAMP-regulated protein kinases A-dependent cell signaling pathways (see PKA); b) Gq alpha subunit-Gβγ complexes which release Gq that then stimulates other cell signaling pathways (e.g. phospholipase C/IP3/cell Ca2+ mobilization/diacylglycerol/protein kinase Cs, calmodulin-modulated myosin light chain kinase, RAF/MEK/Mitogen-activated protein kinases, PKC/Ca2+/Calcineurin/Nuclear factor of activated T-cells; and EGF cellular receptors; and c) Gi alpha subunit-Giβγ) complexes which releases Gi that then simulates phospholipase C to cleave phosphatidylinositol triphosphate into inositol triphosphate that raises intracellular CaCa2 levels thereby regulating Calcium signaling pathways and diacylglycerol that activates certain protein kinase C enzymes )that phosphorylate and thereby regulate target proteins involved in cell signaling (see Protein kinase C#Function). Studies suggest that stimulation of Gsβγ complexes is required for activation of the Gqβγ- and Giβγ-dependent pathways. In certain cells, activation of IP also stimulates G12/G13-Gβγ G proteins to activate the Rho family of GTPases signaling proteins and Gi-Gβγ G proteins to activateRaf/MEK/mitogen-activated kinase pathways.
Function
Studies using animals genetically engineered to lack IP and examining the actions of EP4 receptor agonists in animals as well as animal and human tissues indicate that this receptor serves various functions. It has been regarded as the most successful therapeutic target among the 9 prostanoid receptors.
Platelets
IP gene knockout mice (i.e. IP(-/-) mice) exhibit increased tendency to thrombosis in response to experimentally-induced Endothelium, a result which appears to reflect, at least in part, the loss of IP's anti-platelet activity. IP activation of animal and human platelets inhibits their aggregation response and as one consequence of this inhibition of platelet-dependent blood clotting. The PGI2-IP axis along with the production of nitric oxide, acting together additively and potentially synergistically, are powerful and physiological negative regulators of platelet function and thereby blood clotting in humans. Studies suggest that the PGI2-IP axis is impaired in patients with a tendency to develop pathological thrombosis such as occurs in obesity, diabetes, and coronary artery disease.
Cardiovascular system
IP activation stimulates the dilation of arteries and veins in various animal models as well as in humans. It increases the blood flow through, for example, the pulmonary, coronary, retinal and choroid circulation. Inhaled PGI2 causes a modest fall in diastolic and small fall in systolic blood pressure in humans. This action involves IP's ability to relax vascular smooth muscle and is considered to be one of the fundamental functions of IP receptors. Furthermore, IP(-/-) mice on a high salt diet develop significantly higher levels of hypertension, cardiac fibrosis, and cardiac hypertrophy than control mice. The vasodilating and, perhaps, platelet-inhibiting effects of IP receptors likely underlie its ability suppress hypertension and protect tissues such as the heart in this model as well as the heart, brain, and gastrointestinal tract in various animal models of ischemic injury. Indeed, IP agonists are used to treat patients pathological vasoconstriction diseases. The injection of IP activators into the skin of rodents increases local capillary permeability and swelling; IP(-/-) mice fail to show this increased capillary permeability and swelling in response not only to IP activators but also in a model of carrageenan- or bradykinin-induced paw edema. IP antagonists likewise reduce experimentally-induced capillary permeability and swelling in rats. This actions is also considered a physiological function of IP receptors, but can contribute to the toxicity of IP activators in patients by inducing, for example, life-threatening pulmonary edema.
IP activators inhibit the adherence of circulating platelets and leukocytes adherence to vascular endothelium thereby blocking their entry into sites of tissue disturbance. The activators also inhibit vascular smooth muscle cells from proliferation by blocking these cells' growth cycle and triggering their apoptosis (i.e. cell death). These actions, along with its anti-inflammatory effects, may underlie the ability of IP gene knockout in an ApoE(−/−) mouse model to cause an accelerated rate of developing atherosclerosis.
Inflammation
Mouse studies indicate that the PGI2-IP axis activates cellular signaling pathways that tend to suppress allergic inflammation. The axis inhibits bone marrow-derived dendritic cells (i.e. antigen-presenting cells that process antigen material, present it on their surfaces for delivery to T cells, and otherwise regulate innate and adaptive immune system responses) from producing pro-inflammatory cytokines (e.g. IL-12, TNF-alpha, IL-1-alpha, and IL-6) while stimulating them to increase production of the anti-inflammatory cytokine, IL-10. IP receptor activation of these cells also blocks their lipopolysaccharide-stimulated expression of pro-inflammatory cell surface proteins (i.e. CD86, CD40, and MHC class II molecules) that are critical for developing adaptive immune responses. IL receptor-activated bone marrow-derived dendritic cells showed a greatly reduced ability to stimulate the proliferation of T helper cell as well as the ability of these cells to produce pro-allergic cytokines (i.e. IL-5 and IL-13)s. In a mouse model of allergic inflammation, PGI2 reduced the maturation and migration of lung mature dendritic cells to Mediastinal lymph nodes while increasing the egress of immature dendritic cells away from the lung. These effects resulted in a decrease in allergen-induced responses of the cells mediating allergic reactivity, TH-2 cells. These IP-induced responses likely contribute to its apparent function in inhibiting certain mouse inflammation responses as exemplified by the failure of IP receptor deficient mice to develop full lung airway allergic responses to ovalbumin in a model of allergic inflammation.
In human studies, PGI2 failed to alter bronchoconstriction responses to allergen but did protect against exercise-induced and ultrasonic water-induced bronchoconstriction in asthmatic patients. It also caused bronchodilation in two asthmatic patients. However, these studies were done before the availability of potent and selective IP agonists. These agonists might produce more effective inhibitor results on airways allergic diseases but their toxicity (e.g. pulmonary edema, hypotension) has tended to restrict there study in asthmatic patients.
IP receptors also appear involved in suppressing non-allergic inflammatory responses. IP receptor-deficient mice exhibit a reduction in the extent and progression of inflammation in a model of collagen-induced arthritis. This effect may result from regulating the expression of arthritis-related, pro-inflammatory genes (i.e. those for IL-6, VEGF-A, and RANKL). On the other hand, IP receptors may serve to promote non-allergic inflammatory responses: IP receptor-deficient mice exhibited increased lung inflammation in a model of bleomycin-induced pulmonary fibrosis while mice made to over-express the PGI2-forming enzyme, Prostacyclin synthase, in their airway epithelial cells were protected against lung injury in this model.
Pain perception
IP(-/-) mice exhibit little or no writhing responses in an acetic acid-induced pain model. The mouse IP receptor also appears to be involved in the development of heat-induced hyperalgesia. These and further studies using IP receptor antagonists in rats indicate that IP receptors on pain-perceiving sensory neurons of the dorsal root ganglia as well as on certain neurons in the spinal cord transmit signals for pain, particularly pain triggered by inflammation.
Clinical significance
Toxicity
IP receptor agonists, particularly when used intravenously, have been associated with the rapid development of pulmonary edema, hypotension, bleeding due to inhibition of platelet aggregation, and tachycardia. Clinical use of these agonists is contraindicated in patients suffering many conditions. For example, the IP agonist iloprost is contraindicated in patients with unstable angina; decompensated cardiac failure (unless under close medical supervision); severe cardiac arrhythmias; congenital or acquired heart valve defects; increased risk of bleeding; a history of myocardial infarction in the past 6 months; or a history of cerebrovascular events (e.g. stroke) within 3 months.
Vasoconstriction
IP receptor agonists are front-line drugs to treat pulmonary hypertension. Major drugs in this category include PGI2 itself (i.e. epoprostenol), iloprost, treprostinil, and beraprost with epoprostenol being favored in some studies. However, newly developed IP agonists with favorable pharmacological features such as Selexipag have been granted by the US FDA orphan drug status for the treatment of pulmonary hypertension. IP agonists are also to treat severe vasoconstriction in Raynaud's disease, Raynaud's disease-like syndromes, and scleroderma. Epoprostenol causes improvements in hemodynamic parameters and oxygenation in patients suffering the acute respiratory distress syndrome but due to the limited number of randomized clinical trials and lack of studies investigating mortality, its use cannot be recommended as standard of care for this disease and should be reserved for those refractory to traditional therapies. A meta-analysis of 18 clinical trials on the use of prostanoids including principally IP receptor agonists on patients with severe lower limb peripheral artery disease due to diverse causes found that these drugs may reduce the extent of limb tissue that needed to be amputated. However, the studies did not support extensive use of prostanoids in patients with critical limb ischemia as an adjunct to revascularization or as an alternative to major amputation in cases which cannot undergo revascularization.
Thrombotic diseases
IP receptor agonists have been used to treat Thromboangiitis obliterans, a disease involving blood clotting and inflammation of the small and medium-sized arteries and veins in the hands and feet.
Genomic studies
An adenine (A) to cytosine (C) synonymous substitution at base 984 (i.e. A984C) in exon 3 of PTGIR''' is the most frequent single nucleotide polymorphism (SNP) variant in a sampling of Japanese. This variant was associated with an increase in platelet activation responses in vitro and an increase in incidence of cerebral ischemia. Two other synonymous SNP variants, V53V and S328S, in PTGIR in an Italian population study were associated with enhanced platelet activation response and deep vein thrombosis. The rare SNP variant 795C of 794T in the PTGIR gene is associated with an increased incidence of Aspirin-induced asthma and a greater percentage fall in the forced expiratory volume response of airways to inhalation of an aspirin like compound (lysine-acetyl salicylic acid) in a Korean population sample.
See also
PTGIR'' gene (https://www.wikigenes.org/e/gene/e/5739.html)
PGI2
Prostaglandin receptors
Eicosanoid receptor
References
Further reading
External links
G protein-coupled receptors | Prostacyclin receptor | [
"Chemistry"
] | 3,218 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,522,694 | https://en.wikipedia.org/wiki/Stone%20of%20Tmutarakan | The Stone of Tmutarakan () is a marble slab engraved with the words "In the year 6576 [ A.M., 1068 A.D] the sixth of the Indiction, Prince Gleb measured across the sea on the ice from Tmutarakan to Kerch 14,000 sazhen" («В лето 6576 индикта 6 Глеб князь мерил море по леду от Тмутороканя до Корчева 14000 сажен»).
A sazhen, an old Rus unit of length, was equal to seven feet (or corresponded roughly to a fathom); thus the Kerch Straits, according to the stone, were 88,000 feet or 18.5 miles across (that is, from Kerch to Tmutarakan — the straits themselves are only 4.5 miles wide at their narrowest point, but the distance from the site of Tmutarakan to modern-day Kerch is about 15 miles.) The tenth-century Byzantine Emperor Constantine Porphyrogenitus wrote that the straits were the equivalent of 18 miles across, and this might explain why that measurement appears on the stone, although it is unclear if an eleventh-century prince in Rus would have had access to that information; this uncertainty calls the stone's authenticity into question.
The Prince Gleb referred to in the inscription was Gleb Svyatoslavich, then prince of Tmutarakan. Gleb was later Prince of Novgorod the Great, where he saved Bishop Fedor's life by chopping a sorcerer in half who led a pagan uprising against the bishop. Gleb was eventually killed fighting pagan Finnic tribes in the northern Novgorodian Lands ("the Zavoloch'e" or "Za Volokom", "the Land beyond the Portages") on May 30, 1079.
The stone was discovered on the Taman Peninsula just east of Crimea in 1792 and the inscription was first published in 1794 by Aleksei Musin-Pushkin. The study of the inscription is said to be the first epigraphic study in Russian history. In spite of its importance in the history of Russian epigraphy, a number of scholars have called the stone's provenance into question and consider the stone an eighteenth-century forgery, perhaps done by Romanticists enamored of ancient culture or even as an effort to find precedent for Russian involvement in the Caucasus. The stone is currently housed in the State Hermitage Museum in Saint Petersburg.
See also
List of individual rocks
References
11th-century inscriptions
1792 archaeological discoveries
Archaeological discoveries in Russia
Kievan Rus'
Archaeological collections of the Hermitage Museum
Stones
Tmutarakan
Tmutarakan | Stone of Tmutarakan | [
"Physics"
] | 593 | [
"Stones",
"Physical objects",
"Matter"
] |
14,522,807 | https://en.wikipedia.org/wiki/Xantocillin | Xantocillin (INN), also known as xanthocillin X or ophthocillin, was the first reported natural product found to contain the isocyanide functional group. It was first isolated from Penicillium notatum by Rothe in 1950 and subsequently from several other sources.
See also
Questiomycin A
U0126
References
Isocyanides
4-Hydroxyphenyl compounds | Xantocillin | [
"Chemistry"
] | 90 | [
"Functional groups",
"Organic compounds",
"Isocyanides",
"Organic compound stubs",
"Organic chemistry stubs"
] |
14,523,288 | https://en.wikipedia.org/wiki/Pyrheliometer | A pyrheliometer is an instrument that can measure direct beam solar irradiance. Sunlight enters the instrument through a window and is directed onto a thermopile which converts heat to an electrical signal that can be recorded. The signal voltage is converted via a formula to measure watts per square metre.
Standards
Pyrheliometer measurement specifications are subject to International Organization for Standardization (ISO) and World Meteorological Organization (WMO) standards.
Comparisons between pyrheliometers for intercalibration are carried out regularly to measure the amount of solar energy received.
The aim of the International Pyrheliometer Comparisons, which take place every 5 years at the World Radiation Centre in Davos, is to ensure the world-wide transfer of the World Radiometric Reference.
During this event, all participants bring their instruments, solar-tracking and data acquisition systems to Davos to conduct simultaneous solar radiation measurements with the World Standard Group.
Applications
Typical pyrheliometer measurement applications include scientific meteorological and climate observations, material testing research, and assessment of the efficiency of solar collectors and photovoltaic devices.
Usage
Pyrheliometers are typically mounted on a solar tracker. As the pyrheliometer only 'sees' the solar disk, it needs to be placed on a device that follows the path of the sun.
See also
Actinometer
Active cavity radiometer
Bolometer
Pyrometer
Solar constant
References
External links
Measuring instruments
Radiometry
Meteorological instrumentation and equipment | Pyrheliometer | [
"Technology",
"Engineering"
] | 301 | [
"Telecommunications engineering",
"Meteorological instrumentation and equipment",
"Measuring instruments",
"Radiometry"
] |
14,523,685 | https://en.wikipedia.org/wiki/MAS1L | Mas-related G-protein coupled receptor MRG is a protein that in humans is encoded by the MAS1L gene.
See also
MAS1 oncogene
References
Further reading
G protein-coupled receptors | MAS1L | [
"Chemistry"
] | 43 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,523,778 | https://en.wikipedia.org/wiki/Neuromedin%20U%20receptor%201 | Neuromedin-U receptor 1 is a protein that in humans is encoded by the NMUR1 gene.
See also
Neuromedin U receptor
Limostatin
References
Further reading
External links
G protein-coupled receptors | Neuromedin U receptor 1 | [
"Chemistry"
] | 46 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,523,796 | https://en.wikipedia.org/wiki/Neuromedin%20U%20receptor%202 | Neuromedin-U receptor 2 is a protein that in humans is encoded by the NMUR2 gene.
Ligands
Agonists
synephrine
See also
Neuromedin U receptor
References
Further reading
External links
G protein-coupled receptors | Neuromedin U receptor 2 | [
"Chemistry"
] | 52 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,523,851 | https://en.wikipedia.org/wiki/Cremona%20diagram | The Cremona diagram, also known as the Cremona-Maxwell method, is a graphical method used in statics of trusses to determine the forces in members (graphic statics). The method was developed by the Italian mathematician Luigi Cremona. However, recognizable Cremona diagrams appeared as early as 1725, in Pierre Varignon's posthumously published work, Nouvelle Méchanique ou Statique.
In the Cremona method, first the external forces and reactions are drawn (to scale) forming a vertical line in the lower right side of the picture. This is the sum of all the force vectors and is equal to zero as there is mechanical equilibrium.
Since the equilibrium holds for the external forces on the entire truss construction, it also holds for the internal forces acting on each joint. For a joint to be at rest the sum of the forces on a joint must also be equal to zero. Starting at joint Aorda, the internal forces can be found by drawing lines in the Cremona diagram representing the forces in the members 1 and 4, going clockwise; VA (going up) load at A (going down), force in member 1 (going down/left), member 4 (going up/right) and closing with VA. As the force in member 1 is towards the joint, the member is under compression, the force in member 4 is away from the joint so the member 4 is under tension. The length of the lines for members 1 and 4 in the diagram, multiplied with the chosen scale factor is the magnitude of the force in members 1 and 4.
Now, in the same way the forces in members 2 and 6 can be found for joint C; force in member 1 (going up/right), force in C going down, force in 2 (going down/left), force in 6 (going up/left) and closing with the force in member 1.
The same steps can be taken for joints D, H and E resulting in the complete Cremona diagram where the internal forces in all members are known.
In a next phase the forces caused by wind must be considered. Wind will cause pressure on the upwind side of a roof (and truss) and suction on the downwind side. This will translate to asymmetrical loads but the Cremona method is the same. Wind force may introduce larger forces in the individual truss members than the static vertical loads.
References
Mechanics
Structural system
Diagrams | Cremona diagram | [
"Physics",
"Technology",
"Engineering"
] | 499 | [
"Structural engineering",
"Building engineering",
"Classical mechanics stubs",
"Classical mechanics",
"Structural system",
"Mechanics",
"Mechanical engineering"
] |
14,523,944 | https://en.wikipedia.org/wiki/Pancreatic%20polypeptide%20receptor%201 | Pancreatic polypeptide receptor 1, also known as Neuropeptide Y receptor type 4, is a protein that in humans is encoded by the PPYR1 gene.
Selective Ligands
Agonists
Pancreatic polypeptide
Neuropeptide Y (endogenous agonist, non subtype selective)
Peptide YY
GR-231,118 (mixed NPY1 antagonist / NPY4 agonist, CAS# 158859-98-4)
Antagonists
UR-AK49
See also
Neuropeptide Y receptor
References
External links
Further reading
G protein-coupled receptors | Pancreatic polypeptide receptor 1 | [
"Chemistry"
] | 127 | [
"G protein-coupled receptors",
"Signal transduction"
] |
14,524,293 | https://en.wikipedia.org/wiki/Real-time%20Programming%20Language | Real-time Programming Language (RPL) is a compiled database programming language used on CMC/Microdata/McDonnell Douglas REALITY databases, derived and expanded from the PROC procedure language, with much extra functionality added. It was originally developed under the name "PORC" by John Timmons and Paul Desjardins in about 1975. "PORC" was then further developed by Tim Holland under the employ of George Ridgway's company Systems Management, Inc. (SMI) in Chicago. A number of large scale manufacturing applications were developed in RPL, including that which was in use at Plessey and GEC-Plessey Telecommunications limited in Liverpool and also the Trifid suite of manufacturing software.
Sources
RPL 1.3 Reference Manual (PDF)
"Software House Puts Emphasis on Nitty-Gritty", 10 Sep 1979.
Programming languages | Real-time Programming Language | [
"Technology"
] | 181 | [
"Computing stubs",
"Computer science",
"Computer science stubs"
] |
11,847,421 | https://en.wikipedia.org/wiki/Mediaroom | Mediaroom is a collection of software for operators to deliver IPTV (IPTV) subscription services, including content-protected, live, digital video recorder, video on demand, multiscreen, and applications. These services can be delivered via a range of devices inside and outside customers' homes, including wired and Wi-Fi set top boxes, PCs, tablets, smartphones and other connected devices – over both the operator's managed IP networks as well as "over the top" (OTT) or unmanaged networks.
According to a marketing firm, Mediaroom was the market leader in IPTV for 2014.
History
Microsoft TV platform
Microsoft announced an UltimateTV service from DirecTV in October 2000, based on technology acquired from WebTV Networks (later renamed MSN TV).
The software was called the Microsoft TV platform (which included the Foundation Edition); it had integrated digital video recorder (DVR) and Internet access capabilities. It was released on October 26, 2000. The software to decode and view digital video programming was derived from WebTV (later called MSN TV). UltimateTV had support for picture-in-picture and could record up to 35 hours of video content. The Internet capabilities were provided by Microsoft TV platform software, which was used for the TV guide. The TV guide could display programming schedule for 14 days, and recording could be scheduled for any of the shows. It could also be used to access E-mail. However, Microsoft lost distribution when DirecTV accepted an acquisition bid by Echostar, who had their own DVR. By 2003, it was taken off the market, even though it is still supported by DirecTV and the acquisition by Echostar failed.
The UltimateTV developers in Mountain View, California were eliminated by early 2002.
By June 2002, Moshe Lichtman replaced Jon DeVaan as leader of the division as more reductions were announced.
Foundation Edition
The Microsoft TV Foundation Edition platform integrated video-on-demand (VOD), DVR and HDTV programming with live television programming. It includes an electronic programming guide (EPG) that could be used to access any supported service from a centralized directory. The EPG could be used to search and filter the listings as well. The EPG was released around 2002. Comcast announced it would adopt this software in May 2004. Microsoft TV Foundation Edition platform also included an authoring environment that could be used to create content consumable from the set top box.
IPTV Edition
Microsoft TV IPTV Edition is an IPTV platform for accessing both on-demand as well as live television content over a 2-way IP network, coupled with DVR functionality. It is to be used with cable networks that have an IPTV infrastructure.
Microsoft Mediaroom
The IPTV platform was renamed Microsoft Mediaroom on June 18, 2007 at the NXTcomm conference. In January 2010, Microsoft Mediaroom 2.0 was announced at the International Consumer Electronics Show. On April 8, 2013, Microsoft and Ericsson announced plans for Ericsson to purchase Mediaroom. The sale was completed on September 5, 2013, and the platform officially became Ericsson Mediaroom.
Mediaroom
On February 6, 2014, Ericsson announced it had entered into an agreement to purchase multiscreen video platform company Azuki Systems. Azuki Systems was renamed Ericsson Mediaroom Reach.
MediaKind
On July 10, 2018, it was announced that the new identity of Ericsson Media Solutions is MediaKind. The CEO is Allen Broome.
Products
Current key products in Mediaroom's portfolio include Mediaroom, Mediaroom Reach, and MediaFirst TV Platform.
As of June 2016, Mediaroom TV was used in 65 commercial deployments in 34 countries, delivering services to over 16 million households via more than 30 million devices.
Mediaroom TV platforms are offered by 90 operators, including AT&T, Deutsche Telekom, CenturyLink, Telus, Hawaiian Telcom, Bell Canada (including Bell MTS), Hargray, Singtel, Telefónica SA, Cross Telephone, and Portugal Telecom.
See also
Windows Media Center
Interactive television
Smart TV
List of smart TV platforms and middleware software
10-foot user interface
Set-top box
Tasman (browser engine)
Xbox Video
References
External links
Mediaroom – official website.
Microsoft TV homepage
2007 software
Streaming television
Microsoft software | Mediaroom | [
"Technology"
] | 879 | [
"Multimedia",
"Streaming television"
] |
11,847,599 | https://en.wikipedia.org/wiki/Seletar%20Aerospace%20Park | Seletar Aerospace Park is an industrial park in Singapore catering to the aerospace industries. Located in Seletar, the plan to develop 140 hectares of land adjacent to Seletar Airport will further strengthen Singapore's position as an aviation hub. The development of the new aerospace park is geared towards delivering additional space for industry expansion, and complement existing aerospace activities at Changi North and Loyang.
Seletar Aerospace Park will host an integrated cluster of activities such as aerospace maintenance, repair and overhaul (MRO); design and manufacturing of aerospace systems and components; business and general aviation activities, and an aviation campus for the training of pilots, aviation professionals and technical personnel.
History
In May 2006, the Singapore Government together with the Economic Development Board (EDB) and JTC Corporation unveiled the plan of a new aerospace park. Decision was made when Singapore's aerospace industry has seen soaring growth potential and also a strong demand for aviation-related services. JTC Corporation was asked to carry out the master-planning and infrastructure improvements for Seletar Aerospace Park, in consultation with other government agencies. The development of the new aerospace hub is expected to take care of the industry's land needs for at least 10 years.
A master plan for Seletar Aerospace Park was announced by JTC Corporation on 26 June 2007. The Seletar Airport was upgraded to support the park, including lengthening the airport's runway and upgrading of avionics systems to allow access for bigger aircraft. Aerospace design and manufacturing companies and training schools were given additional space with new roads and infrastructure.
The development of the park would cost more than S$60 million and done in phases. The park is expected to create 10,000 jobs, predominantly skilled and technical positions and double the output of aerospace sector, from 2006's recordof S$6.3 billion.
Existing trees and open fields are conserved as much as possible and more than 30 distinctive trees will not be cut down. 204 of the existing 378 black-and-white bungalows will be conserved as well. 131 units would be used for residential purposes while the rest converted into aerospace training schools and food and beverage outlets. For the same reason,
As of 2016, according to a brochure published by JTC, there were already more than 60 MNCs and local companies in the region, with over 45,700 aircraft movements at the airport annually.
Tenants
The first few tenants moved into their new premises in the third quarter of 2010. Among the front runners are Singapore Technologies Aerospace, Jet Aviation, Airbus Helicopters South East Asia and EADS Innovation Works, all with plans to expand their current facilities at Seletar.
On 20 November 2007, Rolls-Royce plc announced plans to build its first Asian aero engine facility in the Park, slated for completion by end 2009. The facility will complement its existing facility at Derby by concentrating on the assembly and testing of large civil engines such as the Trent 1000 and Trent XWB. It is expected to provide employment for about 330 people, out of a total of 1,600 employees based in Singapore.
On 15 February 2015, jet engine manufacturer Pratt & Whitney officially opened its first Singapore manufacturing facility.
Airbus Asia Training Centre moved from Singapore Airlines's training centre to its new location in the park on 18 April 2016.
Amenities
The Seletar Aerospace Park has several buildings from the British colonial days, that have been preserved and revamped into dining outlets offering different styles of fares, from European to local dishes.
Thirty-two colonial houses have been conserved and redeveloped as part of 'The Oval at Seletar Aerospace Park'.
See also
Seletar Airport
Notes and references
External links
Seletar to be developed into an aerospace park, JTC Corporation 10 May 2006
Singapore to develop aerospace park at Seletar, Channel NewsAsia 10 May 2006
Promising start to Seletar Aerospace Park, The Straits Times 17 June 2007
2010 establishments in Singapore
Industrial parks in Singapore
Seletar
Aerospace
Rolls-Royce
Buildings and structures in North-East Region, Singapore | Seletar Aerospace Park | [
"Physics"
] | 813 | [
"Spacetime",
"Space",
"Aerospace"
] |
11,847,675 | https://en.wikipedia.org/wiki/Symphonie | The Symphonie satellites (2 satellites orbited) were the first communications satellites built by France and Germany (and the first to use three-axis stabilization in geostationary orbit with a bipropellant propulsion system) to provide geostationary orbit injection and station-keeping during their operational lifetime. After the launch of the second flight model, they comprised the first complete telecommunications satellite system (including an on-orbit spare and a dedicated ground control segment). They were the result of a program of formal cooperation between France and Germany.
1963–1970: Beginnings
January 22, 1963: Signing by President Charles de Gaulle and Chancellor Konrad Adenauer of the Élysée Treaty, an agreement for Franco-German cooperation. Start of preliminary studies in France (SAROS project) and in Germany (Olympia project) of communications satellites.
June 1967: Both countries sign an intergovernmental convention concerning the launch and exploitation of an experimental telecommunication satellite (Symphonie) and the development and construction of earth stations necessary for control of the satellites. Formation of a Franco-German board of directors and executive committee. The committee is headed by two executive secretaries – one German and the other French. Belgium joins the program.
1967–1968: A Request for Proposals is launched for the Symphonie satellite, which was answered by two Franco-German consortia. The leaders are, respectively, Nord Aviation (which was to become Aérospatiale after merging with Sud Aviation) for the CIFAS consortium (Consortium Industriel Franco-Allemand pour le satellite Symphonie) and Matra Space for the competing consortium. The CIFAS consortium was selected after the evaluation of bids and undertook, according to the terms of the consultation, a rounding-out of the various roles of the French and German firms in charge of electronic technology.
1969: Beginning of a preliminary definition phase of the satellite, and negotiation of the contract and main subcontracts. Establishment of the industrial project team in Les Mureaux (Nord Aviation) and the client-project group in Brétigny-sur-Orge (CNES). Production of mission specifications, satellite specifications and specifications for the control and exploitation segments.
Industrial Organization
Within the bilateral (CNES – GfW) French-German contract, and under industrial prime contractorship of the CIFAS consortium (which was a European economic interest grouping under French law) composed of six companies (three French and three German), their responsibilities were as follows:
Aérospatiale (France)
Consortium leader and host of the integrated project team at its centre at Les Mureaux.
Structures, and thermal-control subsystems and manufacture of all associated panels, mechanisms, thermal hardware and antenna reflectors (Cannes Space Centre).
Manufacture of the cold gas attitude control system, harness and pyrotechnics (Les Mureaux).
Integration of mechanical and thermal models (Cannes).
Integration of the electrical identification model and the first flight model, Symphonie-A (Les Mureaux).
Messerschmitt-Bölkow-Blohm (MBB) (Germany)
Attitude and Orbit Control Subsystem (AOCS) (Ottobrunn, near Munich).
Manufacture of the hot-gas (bi-propellant) thruster system (Ottobrunn and Lampoldshausen).
Apogee motor (bi-propellant) subsystem (Ottobrunn and Lampoldshausen).
Mechanical ground-support equipment for integration and transport.
Contribution of electrical test sets.
Integration of the qualification prototype and the second flight model, Symphonie-B (Ottobrunn).
Thomson-CSF (France)
Super high frequency (SHF)-antenna subsystem for telecommunications payload and VHF-antenna subsystem for the TT&C (Meudon).
Manufacture of the TT&C system (Gennevilliers and Vélizy-Villacoublay).
Manufacture of equipment for telecommunications transponders, local oscillators and frequency conversion.
Electronic test system (EGSE level 1) for ground testing (integration phase and preparation for flight).
Siemens AG (Germany)
SHF C-band telecommunications transponder subsystem (Munich).
Manufacture of equipment for telecommunications transponders, receiving section and intermediary frequency amplification (Munich).
Contribution of electrical test set.
SAT (France)
Solar-array subsystem (Paris and Lannion).
Manufacture of telemetry encoder (Paris).
Contribution to electrical test sets.
AEG-Telefunken (Germany)
Regulated electric power supply subsystem (Wedel, near Hamburg).
Manufacture of equipment for the telecommunications transponders, transmission section (Backnang – near Stuttgart – and Ulm).
Manufacture of SHF modulators and demodulators for onboard telemetry and telecommand.
Contribution to electrical test sets.
Other major contributions
The six CIFAS companies participated in the integrated project team with detached personnel, headed by Pierre Madon (Aérospatiale).
Belgium officially contributed to the project; its industrial presence included the Ateliers de Constructions Electriques de Charleroi (ACEC) and the space division of ETCA, supplier of the DC-DC converters for the electric power supply; and SAIT for the EGSE test computers.
French and German equipment manufacturers contributed under contract to the consortium members (notably Sodern, SAFT, Crouzet and Starec in France and Teldix and VFW in Germany).
Major test facilities used for the qualification and acceptance tests (space environment simulation): SOPEMEA (a subsidiary of CNES in Toulouse) and IABG in (Ottobrunn).
Calibration of telecommunications performance: Centre National d'Etudes des Telecommunications (CNET, in La Turbie).
1970: Satellite development
1970–1971: Beginning of the Symphonie satellite development program, with a contract signed by General Robert Aubinière (Director General of CNES) and Dr. Mayer (representing the German ministry) Bundesministerium für Wissenschaft und Forschung (BMWF). The CIFAS consortium (organized as a European economic interest grouping and whose administrator at the time was Charles Cristofini) went through several restructurings with the creation of Thomson-CSF, MBB (Messerschmitt Bolkow Blohm), AEG Telefunken and Aérospatiale.
1972: The failure of the Europa II launch vehicle and the abandonment of the program (which had been led by the ELDO) triggers a crisis; it is uncertain if development should continue or, if so, how the satellites will be deployed. After some governmental hesitation, the program continues. The satellites will be launched by the American Thor Delta 2914 satellite-launch vehicles, at the cost of a restrictive agreement; any commercial use of Symphonie is forbidden by the U.S. State Department.
1973: Integration of the test and qualification models of the satellite.
1974: Integration in Les Mureaux of the first flight model (Symphonie-A) and delivery of the satellite.
Launch and lifespan
1974: Symphonie-A was successfully launched from the Kennedy Space Center on December 19, 1974, at 2:39 a.m. UT. (9:39 pm on December 18 local time).
1975: (January 12) President Valéry Giscard d'Estaing of France and German Chancellor Helmut Schmidt exchange their New Year greetings live in a videoconference, via Symphonie-A in geostationary orbit. Symphonie-A is the first geostationary telecommunications satellite built and operated in Europe; some of its technology is groundbreaking.
1975: After its integration at MBB in Ottobrunn and delivery, Symphonie-B is launched from the Kennedy Space Center on August 27, 1975, at 1:42 a.m. UT.(8:42 pm on August 26, local time)
1975: The two satellites are positioned in geostationary orbit at 11.5° west, perfectly fulfilling their mission (two coverage zones, Euro-African and America, can fully benefit from 4 wideband transponders of 90 MHz each); they are the stars of the 1975 Geneva Telecom Show.
1977–1979: For two years beginning in June 1977, Symphonie-A is repositioned over the Indian Ocean at 49° east, where it carries out experiments with India and China.
February 4–7, 1980: An international colloquium is held in Berlin concerning the technical and operational results of the program. Among the presentations, Professor Hubert Curien (then-president of CNES) declared in brief, "Symphonie is the father of Ariane"; it served as the catalyst for the European decision to develop a heavy launch vehicle.
August 12, 1983: Symphonie-A makes its final manoeuvre to a graveyard orbit, and is de-activated after years of service.
December 19, 1984: Exactly ten years after the launch of Symphonie-A, Symphonie-B is also deactivated and placed in a graveyard orbit after nine years of active service. The Symphonie satellites operated successfully for double their expected lifespans, performing hundreds of experiments and expanding the horizons of telecommunications in space.
Uses
Symphonie was the forerunner for numerous telecommunications services. Its prohibition on commercial use may have paradoxically induced a larger program for experimentation of space telecommunications than ever before – both in the number of participating countries and diversity of field applications. As an example of the extent of its use, 40 countries participated in links via Symphonie A and B (east-west and north-south) – from Quebec to Argentina, from Finland to Reunion Island and from China to Indonesia. The Symphonie A and B experiments may be divided into two types:
Humanitarian, cultural and educational experiments.
Technical and scientific experiments.
To these types operational experiments may be added, notably for links between metropolitan France and its overseas departments for telephony and television via satellite. From this viewpoint Symphonie was a forerunner of the French national programs Telecom-1 & 2 and TDF 1 & 2, and the German programs TV-SAT and DFS Kopernikus. The wideband transponders, with their operational flexibility, made it possible to test all-access techniques (single or multiple) and modulation: FDMA (frequency sharing), TDMA (time sharing) and SSMA (spread spectrum). Symphonie terrestrial stations with antennas of various diameters from 16 to 2.2 meters (fixed, portable and mobile) contributed to the renown of the programme around the world. + Several demonstrations were:
Links between United Nations headquarters in New York and Geneva and the UN Blue Helmet squadrons in Jerusalem and Ismaïlia – inaugurating the future communications mode VSAT (very small aperture terminal), using small-diameter ground antennas.
Educational television in Africa, particularly in Côte d'Ivoire and Gabon.
Intercultural exchanges via teleconferencing, telerehabilitation and telemedicine, notably between France and Quebec.
Occasional tele-transmission services (emergency links to disaster areas for the Red Cross, sports reporting and so on).
High-speed, bidirectional links between computers – a forerunner of transcontinental data communications and the Internet.
Synchronization of atomic clocks on an intercontinental scale, to obtain a very high stability of universal time – a forerunner to navigation and positioning satellites GPS and Galileo.
Regional-level tests for mixed analog and digital television and radio broadcasting (now used in many countries – for example Iran, India and China).
One opportunity to demonstrate Symphonie's utility in 1978 was not used; it could have been utilized in Kolwezi (the intervention of French troops in Zaire to protect Europeans living in Katanga), if the French chiefs of staff had followed the above-mentioned UN example rather than calling upon logistical support from the United States.
After Symphonie
Symphonie's ten years of service have been credited with developing the maturity and reliability of space technology, at a time when telecommunications operators were thinking in terms of cables and ground microwave links. After Intelsat (a pioneer in intercontinental telephony), Symphonie led to the development of regional systems with a number of applications (including tele-distribution, tele-education and reliable radio-electrical access) for use in isolated areas with no ground infrastructure and low population density. The Symphonie program was also a training program; it trained engineers, operators and satellite users, who acquired their expertise through the program and distributed it on the European and international level.
Afterwards, new European programs followed and enabled Europe to attain excellence in the field of space telecommunications. The technical success of this precursor program, the demonstration in orbit of the quality of technology born in Europe and the diverse uses benefiting many countries and communities make Symphonie one of the major bases of Europe's success in space.
On the industrial level, it helped launch Europe into major space programs and spurred an industrial restructuring which transformed national industries into European groups. Most of Symphonie's industrial partners contributed to the genesis of the Spacebus programs, and to commercial applications in space communications and direct-to-home TV broadcasting.
Firsts
Symphonie was the:
First three-axis stabilized communications satellite in geostationary orbit with a bipropellant rocket propulsion system (to ensure geostationary orbit injection and orbit control during its entire lifespan).
First European communications satellite system.
Satellites
Symphonie A (aka Symphonie 1, COSPAR 1974-101A), launched 19 December 1974 at 2:39 UT from Kennedy Space Center (Cape Canaveral) LC-17B aboard Delta 2914 rocket to geostationary orbit. Mass of satellite 400 kg, 230 kg in orbit. Planned lifetime was 5 years. Decommissioned August 12, 1983 (moved to graveyard orbit). Mission duration: years.
Symphonie B (aka Symphonie 2, COSPAR 1975-077A), launched 27 August 1975 at 1:42 UT from Kennedy Space Center (Cape Canaveral) LC-17A aboard Delta 2914 rocket to geostationary orbit. Mass of satellite 400 kg, 230 kg in orbit. Planned lifetime was 5 years. Decommissioned December 19, 1984 (moved to graveyard orbit). Mission duration: 9 years.
See also
French version of this article
Sources
"80 years of passion: the Cannes Centre from 1919 to 1999", Editions Version Latine 1999, France.
External links
1969 to 1975, the first steps of Symphonie, Space Corner, Eurospace
Jean-Jacques Dechezelles, Technical presentation of the Symphonie Satellite, Cannes-aero-patrimoine
Footnotes
Satellites orbiting Earth
Spacebus
European space programmes
France–Germany relations | Symphonie | [
"Engineering"
] | 3,124 | [
"Space programs",
"European space programmes"
] |
11,848,030 | https://en.wikipedia.org/wiki/RSS%20editor | An RSS editor is a software application for writing and editing RSS feeds offline (i.e. on the local computer). These applications are also often called desktop RSS editors. Usually RSS feeds are automatically generated out of databases from Content Management Systems (CMS). Some other typical sources for RSS feeds are blogs and websites like Digg. However, there are also several, manually edited RSS feeds (mostly with editorial content), which are maintained offline. After the development and creation of such feeds in an RSS editor application, the feed file is usually transmitted via FTP to the web server. Most RSS editors offer a corresponding, integrated functionality for that.
References
RSS | RSS editor | [
"Technology"
] | 146 | [
"Computing stubs",
"World Wide Web stubs"
] |
11,848,175 | https://en.wikipedia.org/wiki/Fenna%E2%80%93Matthews%E2%80%93Olson%20complex | The Fenna–Matthews–Olson (FMO) complex is a water-soluble complex and was the first pigment-protein complex (PPC) to be structure analyzed by x-ray spectroscopy. It appears in green sulfur bacteria and mediates the excitation energy transfer from light-harvesting chlorosomes to the membrane-embedded bacterial reaction center (bRC). Its structure is trimeric (C3-symmetry). Each of the three monomers contains eight bacteriochlorophyll a (BChl a) molecules. They are bound to the protein scaffold via chelation of their central magnesium atom either to amino acids of the protein (mostly histidine) or water-bridged oxygen atoms (only one BChl a of each monomer).
Since the structure is available, calculating structure-based optical spectra is possible for comparison with experimental optical spectra. In the simplest case only the excitonic coupling of the BChls is taken into account. More realistic theories consider pigment-protein coupling. An important property is the local transition energy (site energy) of the BChls, different for each, due to their individual local protein environment. The site energies of the BChls determine the direction of the energy flow.
Some structural information on the FMO-RC super complex is available, which was obtained by electron microscopy and linear dichroism spectra measured on FMO trimers and FMO-RC complexes. From these measurements, two orientations of the FMO complex relative to the RC are possible. The orientation with BChl 3 and 4 close to the RC and BChl 1 and 6 (following Fenna and Matthews' original numbering) oriented towards the chlorosomes is useful for efficient energy transfer.
Test object
The complex is the simplest PPC appearing in nature and therefore a suitable test object for the development of methods that can be transferred to more complex systems like photosystem I. Engel and co-workers observed that the FMO complex exhibits remarkably long quantum coherence, but after about a decade of debate, it was shown that this quantum coherence has no significance to the functioning of the complex. Furthermore, it was shown that the reported long lived oscillations observed in the spectra are solely due to groundstate vibrational dynamics and do not reflect any energy transfer dynamics.
Quantum light harvesting
Light harvesting in photosynthesis employs both classical and quantum mechanical processes with an energy efficiency of almost 100 percent. For light to produce energy in classical processes, photons must reach reaction sites before their energy dissipates in less than one nanosecond. In photosynthetic processes, this is not possible. Because energy can exist in a superposition of states, it can travel all routes within a material at the same time. When a photon finds the correct destination, the superposition collapses, making the energy available. However, no purely quantum process can be wholly responsible, because some quantum processes slow down the movement of quantized objects through networks. Anderson localization prevents the spread of quantum states in random media. Because the state acts like a wave, it is vulnerable to disruptive interference effects. Another issue is the quantum zeno effect, in which an unstable state never changes if it is continuously measured/watched, because watching constantly nudges the state, preventing it from collapsing.
Interactions between quantum states and the environment act like measurements. The classical interaction with the environment changes the wave-like nature of the quantum state just enough to prevent Anderson localisation, while the quantum zeno effect extends the quantum state's lifetime, allowing it to reach the reaction centre. The proposed long lifetime of quantum coherence in the FMO influenced many scientists to investigate quantum coherence in the system, with Engel's 2007 paper being cited over 1500 times within 5 years of its publication. The proposal of Engel is still debated in literature with the suggestion that the original experiments were interpreted incorrectly assigning the spectral oscillations to electronic coherences instead of ground-state vibrational coherences, which will naturally be expected to live longer due to the narrower spectral width of vibrational transitions.
Computing
The problem of finding a reaction centre in a protein matrix is formally equivalent to many problems in computing. Mapping computing problems onto reaction center searches may allow light harvesting to work as a computational device, improving computational speeds at room temperature, yielding 100-1000x efficiency.
References
Photosynthesis
Phototrophic bacteria
Photosynthetic pigments | Fenna–Matthews–Olson complex | [
"Chemistry",
"Biology"
] | 918 | [
"Photosynthetic pigments",
"Photosynthesis",
"Bacteria",
"Phototrophic bacteria",
"Biochemistry"
] |
11,848,344 | https://en.wikipedia.org/wiki/Department%20of%20Petroleum%20Engineering%20and%20Applied%20Geophysics%2C%20NTNU | In 2017 the department was merged with the Department of Geology and Mineral Resources Engineering, forming the new
Department of Geoscience and Petroleum.
The Norwegian University of Science and Technology (NTNU) is the key university of science and technology in Norway. The Department of Petroleum Engineering and Applied Geophysics (IPT) was established in 1973, shortly after the start of production (Ekofisk field) from the Norwegian continental shelf. The department came to include Petroleum Engineering as well as Geophysics, which is seen as a major strength of the petroleum education at NTNU. The department has elected chairman and vice chairman, and 4 informal groups of professors; geophysics, drilling, production and reservoir engineering. The stated primary purpose of maintaining the informal groups is to take care of the teaching in their respective disciplines. Each group is responsible for offering a sufficient number of courses, semester projects and thesis projects at MSc and PhD levels in their discipline, and to make annual revisions of these in accordance with the needs of society and industry. The total number of professors, associate professors, assistant professors and adjunct professors is 32. The administrative staff is led by a department administrator, and consists of a total of 6 secretaries. The technical support staff reports to the department head, and consists of 8 engineers and technicians. Until 2000, the department was part of the Applied Earth Sciences faculty, together with the Geology-department. After that, the department is part of the Faculty of Engineering Science and Technology (one of a total of 10 departments).
Brief historical statistics of the department:
Established in 1973
More than 2000 graduated M.Sc.´s
More than 150 graduated Ph.D.´s
Around 120 M.Sc.´s graduate every year
Around 10 Ph.D.´s graduate every year
Currently around 120 full-time teachers, researchers and staff
Around 450 students enrolled at B.Sc. and M.Sc. levels
Around 65 PhD students enrolled
Research
The department focus research within the following 5 areas: Petroleum geophysics, Reservoir engineering, Production engineering, Subsea engineering, Drilling engineering and Integrated operations.
Petroleum Geophysics:
Marine seismic sources
Seismic tomography and imaging
Inversion for elastic parameters (AVA) and reservoir parameters
Reservoir seismic and rock physics
Analysis of repeated seismic data (four-dimensional)
Processing of marine controlled source electromagnetic data
Modelling and characterization of anisotropic layered media (seismic and EM)
Reservoir Engineering:
Experimental studies on novel methods for improved oil recovery, like chemical flooding, non-hydrocarbon gas flooding and microbial flooding
Development of improved methods for numerical simulation of enhanced oil recovery processes in conventional, fractured and heterogeneous reservoirs
Development of improved techniques for interpretation of well tests, specially related to compressible reservoirs
Development of phase-behaviour software for non-hydrocarbon injection gases for enhanced oil recovery
Production Engineering
Multiphase flow in wells and pipelines
Pumping and artificial lift
Flow assurance and condition monitoring
Hydrate for transport of natural gas
Processing of oil and gas
Field development
Subsea Engineering:
All-electric subsea control systems including electrical connectors and valve actuators
Experimental and numerical studies of near well bore formation damage related to balanced drilling
Drilling engineering:
Horizontal drilling
Electric pulse drilling
Improved drilling fluid properties
Managed pressure drilling
Integrated operations: The department hosts the Center for Integrated Operations in the Petroleum Industry. Key research areas are drilling, reservoir management, production optimization, operation and maintenance.
International
The department states that it intends to be strongly focused on the international profile with a friendly multi-cultural atmosphere. From the very beginning the international atmosphere existed at IPT in the form of teachers, researchers and students from various countries. IPT has been actively cooperating with countries like Angola, Aserbadjan, Australia, Austria, Bangladesh, Brazil, Canada, France, Germany, Italy, Iran, Mozambique, Netherlands, Russia, Spain, United States, Venezuela; altogether more than 50 countries. There are two 2-years international programs leading to Master's degrees, one in Petroleum Engineering and one in Petroleum Geoscience. Exchange students may take shorter term education within this program. In addition Ph.D-positions are open to qualified international candidates. These positions also constitute the basis for international research cooperation. Professors have individual scientific cooperation with various foreign institutions. The funding comes from Norwegian agencies SIU (NORAD, QUOTA), EnPe (NORAD, QUOTA), The Research Council of Norway, oil companies Statoil, Total, BP, and NTNU Scholarships; also from European Programs (Erasmus, Marie Curie, TIME, Socrates) and others. IPT cultivates personal international contacts as originators of new collaboration. Graduated Ph.D.s represent a particular bridging potential for new joint research.
Innovation
New companies, on average one new company each year, are founded by professors or students, including: Agir Boosting Technology, Geoprobing Technology, DeepSeaAnchors, Markland Technology, Natural Gas Hydrate, PERA, Petrostreamz, Petreco, ResLab, Corrocean, Sensorlink, Seres, Technoguide, Verande, Voxelvision, Waptheweb.
References
Norwegian University of Science and Technology
Norwegian University of Science and Technology, Petroleum
Geophysics organizations
Petroleum engineering schools
Petroleum in Norway
Educational institutions established in 1973
1973 establishments in Norway
1973 in the environment | Department of Petroleum Engineering and Applied Geophysics, NTNU | [
"Engineering"
] | 1,072 | [
"Petroleum engineering",
"Petroleum engineering schools",
"Engineering universities and colleges"
] |
11,848,801 | https://en.wikipedia.org/wiki/Keldysh%20formalism | In non-equilibrium physics, the Keldysh formalism or Keldysh–Schwinger formalism is a general framework for describing the quantum mechanical evolution of a system in a non-equilibrium state or systems subject to time varying external fields (electrical field, magnetic field etc.). Historically, it was foreshadowed by the work of Julian Schwinger and proposed almost simultaneously by Leonid Keldysh and, separately, Leo Kadanoff and Gordon Baym. It was further developed by later contributors such as O. V. Konstantinov and V. I. Perel.
Extensions to driven-dissipative open quantum systems is given not only for bosonic systems, but also for fermionic systems.
The Keldysh formalism provides a systematic way to study non-equilibrium systems, usually based on the two-point functions corresponding to excitations in the system. The main mathematical object in the Keldysh formalism is the non-equilibrium Green's function (NEGF), which is a two-point function of particle fields. In this way, it resembles the Matsubara formalism, which is based on equilibrium Green functions in imaginary-time and treats only equilibrium systems.
Time evolution of a quantum system
Consider a general quantum mechanical system. This system has the Hamiltonian . Let the initial state of the system be the pure state . If we now add a time-dependent perturbation to this Hamiltonian, say , the full Hamiltonian is and hence the system will evolve in time under the full Hamiltonian. In this section, we will see how time evolution actually works in quantum mechanics.
Consider a Hermitian operator . In the Heisenberg picture of quantum mechanics, this operator is time-dependent and the state is not. The expectation value of the operator is given by
where, due to time evolution of operators in the Heisenberg picture, . The time-evolution unitary operator is the time-ordered exponential of an integral, (Note that if the Hamiltonian at one time commutes with the Hamiltonian at different times, then this can be simplified to .)
For perturbative quantum mechanics and quantum field theory, it is often more convenient to use the interaction picture. The interaction picture operator is
where . Then, defining we have
Since the time-evolution unitary operators satisfy , the above expression can be rewritten as
,
or with replaced by any time value greater than .
Path ordering on the Keldysh contour
We can write the above expression more succinctly by, purely formally, replacing each operator with a contour-ordered operator , such that parametrizes the contour path on the time axis starting at , proceeding to , and then returning to . This path is known as the Keldysh contour. has the same operator action as (where is the time value corresponding to ) but also has the additional information of (that is, strictly speaking if , even if for the corresponding times ).
Then we can introduce notation of path ordering on this contour, by defining , where is a permutation such that , and the plus and minus signs are for bosonic and fermionic operators respectively. Note that this is a generalization of time ordering.
With this notation, the above time evolution is written as
Where corresponds to the time on the forward branch of the Keldysh contour, and the integral over goes over the entire Keldysh contour. For the rest of this article, as is conventional, we will usually simply use the notation for where is the time corresponding to , and whether is on the forward or reverse branch is inferred from context.
Keldysh diagrammatic technique for Green's functions
The non-equilibrium Green's function is defined as .
Or, in the interaction picture, . We can expand the exponential as a Taylor series to obtain the perturbation series
.
This is the same procedure as in equilibrium diagrammatic perturbation theory, but with the important difference that both forward and reverse contour branches are included.
If, as is often the case, is a polynomial or series as a function of the elementary fields , we can organize this perturbation series into monomial terms and apply all possible Wick pairings to the fields in each monomial, obtaining a summation of Feynman diagrams. However, the edges of the Feynman diagram correspond to different propagators depending on whether the paired operators come from the forward or reverse branches. Namely,
where the anti-time ordering orders operators in the opposite way as time ordering and the sign in is for bosonic or fermionic fields. Note that is the propagator used in ordinary ground state theory.
Thus, Feynman diagrams for correlation functions can be drawn and their values computed the same way as in ground state theory, except with the following modifications to the Feynman rules: Each internal vertex of the diagram is labeled with either or , while external vertices are labelled with . Then each (unrenormalized) edge directed from a vertex (with position , time and sign ) to a vertex (with position , time and sign ) corresponds to the propagator . Then the diagram values for each choice of signs (there are such choices, where is the number of internal vertices) are all added up to find the total value of the diagram.
See also
Spin Hall effect
Kondo effect
References
Other
Gianluca Stefanucci and Robert van Leeuwen (2013). "Nonequilibrium Many-Body Theory of Quantum Systems: A Modern Introduction" (Cambridge University Press, 2013). DOI: https://doi.org/10.1017/CBO9781139023979
Robert van Leeuwen, Nils Erik Dahlen, Gianluca Stefanucci, Carl-Olof Almbladh and Ulf von Barth, "Introduction to the Keldysh Formalism", Lectures Notes in Physics 706, 33 (2006). arXiv:cond-mat/0506130
Condensed matter physics
Electromagnetism | Keldysh formalism | [
"Physics",
"Chemistry",
"Materials_science",
"Engineering"
] | 1,256 | [
"Electromagnetism",
"Physical phenomena",
"Phases of matter",
"Materials science",
"Fundamental interactions",
"Condensed matter physics",
"Matter"
] |
11,848,927 | https://en.wikipedia.org/wiki/Personoid | Personoid is the concept coined by Stanisław Lem, a Polish science-fiction writer, in Non Serviam, from his book A Perfect Vacuum (1971). His personoids are an abstraction of functions of human mind and they live in computers; they do not need any human-like physical body.
In cognitive and software modeling, personoid is a research approach to the development of intelligent autonomous agents.
In frame of the IPK (Information, Preferences, Knowledge) architecture, it is a framework of abstract intelligent agent with a cognitive and structural intelligence. It can be seen as an essence of high intelligent entities.
From the philosophical and systemics perspectives, personoid societies can also be seen as the carriers of a culture. According to N. Gessler, the personoids study can be a base for the research on artificial culture and culture evolution.
Personoids on TV and cinema
Welt am Draht (1973)
The Thirteenth Floor (1999)
See also
Android
Humanoid
Intelligence
Artificial Intelligence
Culture
Computer Science
Cognitive Science
Anticipatory science
Memetics
References
Stanisław Lem's book Próżnia Doskonała (1971). The collection of book reviews of nonexistent books. Translated into English by Michael Kandel as A Perfect Vacuum (1983).
Personetics.
Personoids Organizations Framework: An Approach to Highly Autonomous Software Architectures , ENEA Report (1998).
Paradigms of Personoids, Adam M. Gadomski 1997 .
Computer Models of Cultural Evolution. Nicholas Gessler. In EVOLUTION IN THE COMPUTER AGE - Proceedings of the Center for the Study of Evolution and the Origin of Life, edited by David B. and Gary B. Fogel. Jones and Bartlett Publishers, Sudbury, Massachusetts (2002).
Hypothetical technology
Computing terminology
Fiction about computing
Scientific method
Artificial intelligence | Personoid | [
"Technology"
] | 365 | [
"Computing terminology"
] |
11,848,991 | https://en.wikipedia.org/wiki/Mallet%20%28habit%29 | A mallet is a small-tree form of Eucalyptus found in Western Australia. Unlike the mallee, it is single-stemmed and lacks a lignotuber. Species of this form have a relatively long, slender trunk, steeply-angled branches, often a conspicuously dense terminal crown, and sometimes form thickets.
Mallet species include:
Brown mallet (Eucalyptus astringens)
Blue mallet, blue-leaved mallet, Gardner's mallet (Eucalyptus gardneri)
Green mallet (Eucalyptus clivicola)
Salt River mallet, Sargent's mallet (Eucalyptus sargentii)
Silver mallet (Eucalyptus falcata or Eucalyptus ornata)
Steedman's mallet (Eucalyptus steedmanii)
Swamp mallet (Eucalyptus spathulata)
White mallet (Eucalyptus falcata or Eucalyptus spathulata)
Fuchsia gum (Eucalyptus dolichorhyncha)
See also
Mallee
Marlock
Gimlet
References
Plant morphology | Mallet (habit) | [
"Biology"
] | 205 | [
"Plant morphology",
"Plants"
] |
11,849,133 | https://en.wikipedia.org/wiki/Berkovich%20tip | A Berkovich tip is a type of nanoindenter tip used for testing the indentation hardness of a material. It is a three-sided pyramid which is geometrically self-similar. The popular Berkovich now has a very flat profile, with a total included angle of 142.3° and a half angle of 65.27°, measured from the axis to one of the pyramid flats. This Berkovich tip has the same projected area-to-depth ratio as a Vickers indenter. The original tip shape was invented by Russian scientist E. S. Berkovich in the USSR around 1950, which has a half angle of 65.03°.
As it is three-sided, it is easier to grind these tips to a sharp point and so is more readily employed for nanoindentation tests. It is typically used to measure bulk materials and films greater than thick.
References
Hardness tests
Soviet inventions
Russian inventions | Berkovich tip | [
"Materials_science"
] | 189 | [
"Hardness tests",
"Materials testing"
] |
11,849,160 | https://en.wikipedia.org/wiki/Tyrosine%20kinase%202 | Non-receptor tyrosine-protein kinase TYK2 is an enzyme that in humans is encoded by the TYK2 gene.
TYK2 was the first member of the JAK family that was described (the other members are JAK1, JAK2, and JAK3). It has been implicated in IFN-α, IL-6, IL-10 and IL-12 signaling.
Function
This gene encodes a member of the tyrosine kinase and, to be more specific, the Janus kinases (JAKs) protein families. This protein associates with the cytoplasmic domain of type I and type II cytokine receptors and promulgate cytokine signals by phosphorylating receptor subunits. It is also component of both the type I and type III interferon signaling pathways. As such, it may play a role in anti-viral immunity.
Cytokines play pivotal roles in immunity and inflammation by regulating the survival, proliferation, differentiation, and function of immune cells, as well as cells from other organ systems. Hence, targeting cytokines and their receptors is an effective means of treating such disorders. Type I and II cytokine receptors associate with Janus family kinases (JAKs) to affect intracellular signaling. Cytokines including interleukins, interferons and hemopoietins activate the Janus kinases, which associate with their cognate receptors.
The mammalian JAK family has four members: JAK1, JAK2, JAK3 and tyrosine kinase 2 (TYK2). The connection between Jaks and cytokine signaling was first revealed when a screen for genes involved in interferon type I (IFN-1) signaling identified TYK2 as an essential element, which is activated by an array of cytokine receptors. TYK2 has broader and profound functions in humans than previously appreciated on the basis of analysis of murine models, which indicate that TYK2 functions primarily in IL-12 and type I-IFN signaling. TYK2 deficiency has more dramatic effects in human cells than in mouse cells. However, in addition to IFN-α and -β and IL-12 signaling, TYK2 has major effects on the transduction of IL-23, IL-10, and IL-6 signals. Since, IL-6 signals through the gp-130 receptor-chain that is common to a large family of cytokines, including IL-6, IL-11, IL-27, IL-31, oncostatin M (OSM), ciliary neurotrophic factor, cardiotrophin 1, cardiotrophin-like cytokine, and LIF, TYK2 might also affect signaling through these cytokines. Recently, it has been recognized that IL-12 and IL-23 share ligand and receptor subunits that activate TYK2. IL-10 is a critical anti-inflammatory cytokine, and IL-10−/− mice suffer from fatal, systemic autoimmune disease.
TYK2 is activated by IL-10, and its deficiency affects the ability to generate and respond to IL-10. Under physiological conditions, immune cells are, in general, regulated by the action of many cytokines and it has become clear that cross-talk between different cytokine-signalling pathways is involved in the regulation of the JAK–STAT pathway.
Role in inflammation
It is now widely accepted that atherosclerosis is a result of cellular and molecular events characteristic of inflammation. Vascular inflammation can be caused by upregulation of Ang-II, which is produced locally by inflamed vessels and induces synthesis and secretion of IL-6, a cytokine responsible for induction of angiotensinogen synthesis in liver through JAK/STAT3 pathway, which gets activated through high affinity membrane protein receptors on target cells, termed IL-6R-chain recruiting gp-130 that is associated with tyrosine kinases (Jaks 1/2, and TYK2 kinase). Cytokines IL-4 and IL-13 gets elevated in lungs of chronically suffered asthmatics. Signalling through IL-4/IL-13 complexes is thought to occur through IL-4Rα-chain, which is responsible for activation of JAK-1 and TYK2 kinases. A role of TYK2 in rheumatoid arthritis is directly observed in TYK2-deficient mice that were resistant to experimental arthritis. TYK2−/− mice displayed a lack of responsiveness to a small amount of IFN-α, but they respond normally to a high concentration of IFN-α/β. In addition, these mice respond normally to IL-6 and IL-10, suggesting that TYK2 is dispensable for mediating for IL-6 and IL-10 signaling and does not play a major role in IFN-α signaling. Although TYK2−/− mice are phenotypically normal, they exhibit abnormal responses to inflammatory challenges in a variety of cells isolated from TYK2−/− mice. The most remarkable phenotype observed in TYK2-deficient macrophages was lack of nitric oxide production upon stimulation with LPS. Further elucidation of molecular mechanisms of LPS signaling, showed that TYK2 and IFN-β deficiency leads resistance to LPS-induced endotoxin shock, whereas STAT1-deficient mice are susceptible. Development of a TYK2 inhibitor appears to be a rational approach in the drug discovery.
Clinical significance
A mutation in this gene has been associated with hyperimmunoglobulin E syndrome (HIES), a primary immunodeficiency characterized by elevated serum immunoglobulin E.
TYK2 appears to play a central role in the inflammatory cascade responses in the pathogenesis of immune-mediated inflammatory diseases such as psoriasis. The drug deucravacitinib (marketed as Sotyktu), a small-molecule TYK2 inhibitor, was approved for moderate-to-severe plaque psoriasis in 2022.
The P1104A allele of TYK2 has been shown to increase risk of tuberculosis when carried as a homozygote; population genetic analyses suggest that the arrival of tuberculosis in Europe drove the frequency of that allele down three-fold about 2,000 years before present.
Interactions
Tyrosine kinase 2 has been shown to interact with FYN, PTPN6, IFNAR1, Ku80 and GNB2L1.
References
Further reading
Signal transduction
Tyrosine kinases | Tyrosine kinase 2 | [
"Chemistry",
"Biology"
] | 1,382 | [
"Biochemistry",
"Neurochemistry",
"Signal transduction"
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11,849,358 | https://en.wikipedia.org/wiki/ETV6 | ETV6 (i.e. translocation-Ets-leukemia virus) protein is a transcription factor that in humans is encoded by the ETV6 (previously known as TEL) gene. The ETV6 protein regulates the development and growth of diverse cell types, particularly those of hematological tissues. However, its gene, ETV6 frequently suffers various mutations that lead to an array of potentially lethal cancers, i.e., ETV6 is a clinically significant proto-oncogene in that it can fuse with other genes to drive the development and/or progression of certain cancers. However, ETV6 is also an anti-oncogene or tumor suppressor gene in that mutations in it that encode for a truncated and therefore inactive protein are also associated with certain types of cancers.
Gene
The human ETV6 gene is located at position "13.2" on the short (i.e. "p") arm of chromosome 12, i.e. its notated position is 12p13.2. The gene has 8 exons and two start codons, one located at exon 1 at the start of the gene and an alternative located upstream of exon 3. ETV6 codes for a full length protein consisting of 452 amino acids; the gene is expressed in virtually all cell types and tissues. Mice depleted of the ETV6 gene by Gene knockout die between day 10.5 and 11.5 of embryonic life with defective yolk sac angiogenesis and extensive losses in mesenchymal and neural cells due to apoptosis. Other genetic manipulation studies in mice indicate that the gene is required for the development and maintenance of bone marrow-based blood cell formation and the vascular network.
Protein
The human ETV6 protein is a member of the ETS transcription factor family; however, it more often acts to inhibit than stimulate transcription of its target genes. ETV6 protein contains 3 domains: a) the pointed N-terminal (i.e. PNT) domain which forms oligomer partners with itself as well as other transcription factors (e.g. FLI1) and is required for ETV6's transcriptional repressing activity; b) the central regulatory domain; and c) the C-terminal DNA-binding domain, ETS, which binds to the consensus DNA sequence, 5-GGAA/T-3 within a 9-to-10 bp sequence, in the target genes it regulates. ETV6 interacts with other proteins that regulate the differentiation and growth of cells. It binds to and thereby inhibits FLI1, another member of the ETS transcription factor family, which is active in promoting the maturation of blood platelet-forming megakaryocytes and blocking the Cellular differentiation of erythroblasts into red blood cells; this results in the excessive proliferation and abnormal morphology of erythroblasts. ETV6 likewise binds to HTATIP, a histone acetyl transferase that regulates the expression of various genes involved in gene transcription, DNA repair, and cellular apoptosis; this binding promotes the transcription-repressing activity of ETV6.
Medical significance
Inherited mutations
Rare missense and other loss of function mutations in ETV6 cause thrombocytopenia 5, an autosomal dominant familial disease characterized by variable thrombocytopenia (blood platelet counts from 5% to 90% of normal), mild to modest bleeding tendencies, and bone marrow biopsy findings of abnormal appearing megakaryocytes (i.e. nuclei with fewer than the normal number of lobulations) and red cell macrocytosis. Thrombocytopenia 5 is associated with an increased incidence of developing hematological (e.g. chronic myelomonocytic leukemia, acute myelocytic leukemia, B cell acute lymphoblastic leukemia, mixed phenotype acute leukemia, Myelodysplastic syndrome, and multiple myeloma) and non-hematological (e.g. skin and colon) cancers as well as non-malignant diseases such as refractory anemia myopathies, and gastroesophageal reflux disease.
Two unrelated kindreds were found to have autosomal dominant inherited mutations in the ETV6 gene, one family with a germline DNA substitution termed L349P that lead to replacing leucine with proline at amino acid 349 in the DNA binding domain of the ETV6, the second, termed N385fs, in germline DNA caused the lose of five base pairs ETV6 and a truncated ETV6 protein. Both mutant proteins failed to enter cell nuclei normally and had a reduced capacity to target genes regulated by the normal ETV6 protein. Afflicted members of these families had low platelet counts (i.e. thrombocytopenia) and acute lymphoblastic leukemia. Fifteen members of the two kindreds had thrombocytopenia, five of whom also had acute lymphoblastic leukemia. The L249P kindred also had one family member with renal cell carcinoma and another family member with Duodenal cancer. The relationship of these two cancers to the L249P mutation has not been investigated. In all events these two familial thrombocytopenia syndromes appear distinctly different than the thrombocytopenia 5 syndrome.
Treatment
Family members with thrombocytopenia 5 need to be regularly monitored with complete blood count and blood smear screenings to detect the early changes brought on by the malignant transformations of this disease into hematological neoplasms. Patients who developed these transformations have generally been treated similarly to patients who have the same hematological neoplasms but on a non-familial basis. Patients developing non-malignant hematological or non-hematological solid tumor manifestations of thrombocytopenia 5 are also treated like to patients with the same but no-familial disease.
The acute lymphoblastic leukemia associated with L349P or N385fs mutations in ETV6 appeared far less sensitive to standard chemotherapy for acute lymphoblastic leukemia with 2 among 3 family members moving rather quickly from chemotherapy to bone marrow transplantation and the third family member expiring. This suggest that these mutation-related forms of acute lymphoblastic leukemia require aggressive therapy.
Acquired mutations
The ETV6 gene is prone to develop a wide range of acquired mutations in hematological precursor cells that lead to various types of leukemia and/or lymphoma. It may also suffer a smaller number of mutations in non-hematological tissues that leads to solid tumors. These mutations involve chromosome translocations which fuse the ETV6 on chromosome 12's the short (i.e. "p") arm ("q" stands for long arm) at position p13.2 (site notation: 12p12.2) near to a second gene on another chromosome or, more rarely, its own chromosome. This creates a fusion gene of the oncogene category which encodes a chimeric protein that promotes the malignant growth of its parent cells. It may be unclear which portion of the newly formed oncoprotein contributes to the ensuing malignancy but fusions between ETV6 and proteins with tyrosine kinase activity generally are converted from a protein with tightly regulated tyrosine kinase activity to an uncontrolled and continuously active tyrosine kinase that thereby promotes the malignant transformation of its parent cells.
Hematological malignancies
The following table lists the more frequently occurring genes to which ETV6 fuses, the function of these genes, these genes' chromosomal locations, the notation designating the most common sites of the translocations of these fused genes, and the malignancies resulting from these translocations. These translocation mutations commonly occur in pluripotent hematopoietic stem cells that differentiate into various types of mature hematological cells. Consequently, a given mutation may lead to various types of hematological malignancies. The table includes abbreviations for tyrosine kinase receptor (TK receptor), non-receptor tyrosine kinase (non-receptor TK), homeobox protein type of transcription factor (homeobox protein), acute lymphocytic leukemia (ALL), Philadelphia chromosome negative chronic myelogenous leukemia (Ph(-)CML), myelodysplastic syndrome (MDS), myeloproliferative neoplasm (MPN), and acute myeloid leukemia (AML). The presence of ETV6 gene mutations in myelodysplastic syndromes is associated with shortened survival.
In addition to the fusion gene-producing translocations given in the table, ETV6 has been reported to fuse with other genes in very rare cases (i.e. 1-10 published reports). These translocations lead to one or more of the same types of hematological malignancies listed in the table. Thus, the ETV6 gene reportedly forms translocation-induced fusion genes with: a) tyrosine kinase receptor gene FGFR3; b) non-receptor tyrosine kinase genes ABL2, NTRK3, JAK2, SYK, FRK, and LYN; c) transcription factor genes MN1 and PER1; d) homeobox protein transcription factor CDX2; e) Protein tyrosine phosphatase receptor-type R gene PTPRR; f) transcriptional coactivator for nuclear hormone receptors gene NCOA2; f) Immunoglobulin heavy chain gene IGH; g) enzyme genes TTL (adds and removes tyrosine residues on α-tubulin), GOT1 (an Aspartate transaminase), and ACSL6 (a Long-chain-fatty-acid—CoA ligase); h) transporter gene ARNT (binds to ligand-bound aryl hydrocarbon receptor to aid in its movement to the nucleus where it promotes the expression of genes involved in xenobiotic metabolism); i) unknown function genes CHIC2, MDS2, FCHO2 and BAZ2A.; and j) non-annotated gene STL (which has no long open reading frame).
At least 9 frameshift mutations in the'ETV6 gene have been associated with ~12% of adult T cell Acute lymphoblastic leukemia cases. These mutations involve insertions or deletions in the gene that lead to its encoding a truncated and therefore inactive ETV6 protein. These mutations commonly occur alongside mutations in another oncogene, NOTCH1, which is associated with T cell acute lymphoblastic lymphoma quite independently of ETV6. It is suggested that suppressor mutations in the ETV6 gene may be a contributing factor in the development ant/or progression of this leukemia type.
Treatment
Patients developing hematological malignancies secondary to the ETV6 gene fusion to receptor tyrosine kinases and non-receptor tyrosine kinases may be sensitive to therapy with tyrosine kinase inhibitors. For example, patients with clonal eosinophilias due to PDGFRA or PDGFRB fusion genes experience long-term, complete remission when treated with are highly sensitive tyrosine kinase inhibitor, gleevec. Larotrectinib, entrectinib, merestinib, and server other broadly acting tyrosine kinase inhibitors target the NTRK3 gene. Many of these drugs are in phase 1 or phase 2 clinical trials for the treatment of ETV6-NTRK3-related solid tumors and may ultimately prove useful for treating hematologic malignancies associated with this fusion gene. Clinical trials have found that the first generation tyrosine kinase inhibitors sorafenib, sunitinib, midostaurin, lestaurtinib have shown some promise in treating acute myelogenous leukemia associated with the FLT3-TKI fusion gene; the second generation tyrosine kinase inhibitors quizartinib and crenolanib which are highly selective in inhibiting the FLT3 protein, have shown significant promise in treating relapsed and refractory acute myelogenous leukemia related to the FLT3-TKI fusion gene. One patient with ETV6-FLT3-related myeloid/lymphoid neoplasm obtained a short term remission on sunitinib and following relapse, on sorafenib suggesting that the cited FLT3 protein tyrosine kinase inhibitors may prove useful for treating ETV6-FLT-related hematologic malignancies. Two patients suffering hematologic malignancies related to PCM1-JAK2 or BCR-JAK2 fusion genes experienced complete and cytogenetic remissions in response to the tyrosine kinase inhibitor ruxolitinib; while both remissions were short-term (12 months), these results suggest that tyrosine kinase inhibitors that target JAK2 may be of some use for treating hematologic malignancies associated with ETV6-JAK2 fusion stems. An inhibitor of SYK tyrosine kinase, TAK-659 is currently undergoing Phase I clinical trials for advanced lymphoma malignancies and may prove to be useful in treating this disease when associated with the ETV6-SYK fusion gene. It is possible that hematological malignancies associated with ETV6 gene fusions to either the SYK or FRK tyrosine kinase genes may someday be shown susceptible to tyrosine kinase inhibitor therapy. However, children with ETV6-RUNX1-associated acute lymphoblastic leukemia are in an especially good-risk subgroup and therefore have been almost uniformly treated with standard-risk chemotherapy protocols.
Hematological malignancies associated with ETY6 gene fusions to other transcription factor genes appear to reflect a loss or gain in function of ETV6 and/or the other genes in regulating expression of their target genes; this results in the formation or lack of formation of products which influence cell growth, proliferation, and/or survival. In vitro studies of ETV6-RUNX, ETV6-MN1, ETV6-PER1, and ETV6-MECOM fusion genes support this notion. Thus, the ETV6-MECOM fusion gene is overexpressed because it is driven by the promoter derived from ETV6 whereas the ETV6-RUNX, ETV6-MN1, and ETV6-PER1 fusion genes produce chimeric proteins which lack ETV6 protein's gene-suppressing activity. The chimeric protein products of ETV6 gene fusions with ARNT, TTL, BA22A, FCHO2, MDS2, and CHIC2 likewise lack ETV6 protein's transcription factor activity. Gene fusions between ETV6 and the homeobox gens (i.e. CDX2, PAX5, and MNX1) produce chimeric proteins with lack either ETV6s and/or CDX2s, PAX5s or MNX1s transcription factor activity. In all events, hematological malignancies associated with these fusion genes have been treated with standard chemotherapy protocols selected on the basis of the malignancies phenotype.
Solid Tumors
Mutations in the ETV6 gene are also associated with solid tumors. In particular, the ETV6-NTRK3 fusion gene occurs in and is thought or proposed to drive certain types of cancers. These cancers include secretory breast cancer (also termed juvenile breast cancer), mammary analogue secretory carcinoma of the parotid and other salivary glands, congenital fibrosarcoma, congenital mesoblastic nephroma, inflammatory myofibroblastic tumor, and radiation-induced papillary thyroid carcinoma.
Treatment
The treatment of ETV6 gene-associated solid tumors has not advanced as far as that for ETV6 gene-associated hematological malignancies. It is proposed that tyrosine kinase inhibitors with specificity for NTRK3's tyrosine kinase activity in ETV6-NTRK3 gene-associated solid tumors may be of therapeutic usefulness. Entrectinib, a pan-NTRK as well as an ALK and ROS1 tyrosine kinase inhibitor has been found useful in treating a single patient with ETV6-NRTK3 fusion gene-associated mammary analogue secretory carcinoma and lends support to the clinical development of NTRK3-directed tyrosine kinase inhibitors to treat ETV6-NTRK3 fusion protein associated malignancies. Three clinical trials are in the recruitment phase for determining the efficacy of treating a wide range of solid tumors associated with mutated, overactive tyrosine kinase proteins, including the ETV6-TRK3 protein, with larotrectinib, a non-selective inhibitor of NTRK1, NTRK2, and NTRK3 tyrosine kinases.
See also
ETV6-NTRK3 gene fusion
TEL-JAK2
References
Further reading
External links
Drosophila anterior open - The Interactive Fly
Oncogenes
Tyrosine kinases
Transcription factors | ETV6 | [
"Chemistry",
"Biology"
] | 3,650 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
11,849,545 | https://en.wikipedia.org/wiki/Bonnet%20theorem | In the mathematical field of differential geometry, the fundamental theorem of surface theory deals with the problem of prescribing the geometric data of a submanifold of Euclidean space. Originally proved by Pierre Ossian Bonnet in 1867, it has since been extended to higher dimensions and non-Euclidean contexts.
Bonnet's theorem
Any surface in three-dimensional Euclidean space has a first and second fundamental form, which automatically are interrelated by the Gauss–Codazzi equations. Bonnet's theorem asserts a local converse to this result.
Given an open region in , let and be symmetric 2-tensors on , with additionally required to be positive-definite. If these are smooth and satisfy the Gauss–Codazzi equations, then Bonnet's theorem says that is covered by open sets which can be smoothly embedded into with first fundamental form and second fundamental form (relative to one of the two choices of unit normal vector field) . Furthermore, each of these embeddings is uniquely determined up to a rigid motion of .
Bonnet's theorem is a corollary of the Frobenius theorem, upon viewing the Gauss–Codazzi equations as a system of first-order partial differential equations for the two coordinate derivatives of the position vector of an embedding, together with the normal vector.
General formulations
Bonnet's theorem can be naturally formulated for hypersurfaces in a Euclidean space of any dimension, and the result remains true in this context. Furthermore, the theorem can be extended from Bonnet's local formulation to a global formulation, allowing to be any connected and simply-connected smooth manifold, with the result asserting the existence and uniqueness (up to a rigid motion) of a smooth immersion of as a hypersurface of Euclidean space with first fundamental form and second fundamental form . The idea of the proof is to use the existence theory from the local formulation to construct the immersion along arbitrary curves emanating from a single point. Simple-connectedness is used to say that any two such curves with a common endpoint are homotopic (through paths fixing the endpoints), and uniqueness from the local formulation implies that the value of the immersion at the endpoint must be fixed through the homotopy, so that an immersion results which is well-defined on the entire manifold.
In this global formulation, existence would not hold in general if the condition of simple-connectedness were removed. This can be seen from the nonexistence of a hypersurface immersion of the torus whose first fundamental form is flat and whose second fundamental form is zero.
The theorem can also be extended, beyond the context of hypersurfaces, to the theory of submanifolds of arbitrary codimension. This is more complicated to formulate, because in addition to the first and second fundamental forms, there is also the (generally nontrivial) connection in the normal bundle which must be taken into account. In this generality, the fundamental theorem of surface theory subsumes the fundamental theorem of curves.
In this general context, the ambient Euclidean space can also be replaced by any connected and geodesically complete Riemannian manifold of constant curvature, which (as with the more special case of higher codimension) requires a suitably extended formulation of the Gauss–Codazzi equations.
References
Bibliography
Surfaces
Theorems in differential geometry | Bonnet theorem | [
"Mathematics"
] | 686 | [
"Theorems in differential geometry",
"Theorems in geometry"
] |
11,849,588 | https://en.wikipedia.org/wiki/New%20Galilee%20%28the%20Sixth%20Epoch%29 | The New Galilee is the name given in the Western Wisdom Teachings to "a new heaven and a new earth" mentioned in the Bible. From the viewpoint of these Christian esoteric teachings, the New Galilee represents the future Sixth Epoch in mankind's evolutionary path and will see the transition of humanity to the etheric region of the Earth, where “sorrow and pain will cease and he[man] will have entered the path to the city of peace--Jer-u-salem, the future New Jerusalem to be established within, the heavenly ‘bride’ of the Christ's Race in the making.”
Usage in the Western Wisdom Teachings
According to the Rosicrucian writings of Max Heindel the sixth sub-race of the current Aryan Epoch (the fifth epoch) has evolved among the Slavic peoples and the seventh sub-race is now evolving from this sixth sub-race. Heindel refers that the United States is the melting pot to form the last race in human evolution that will exist at the beginning of the Sixth Epoch, the New Galilee:
See also
Second Coming (Esoteric Christian teachings)
Last Judgment (Esoteric Christian tradition)
The New Earth
References
External links
Rays from the Rose Cross: Christ is the Divine Messenger
Astrological ages
Christian cosmology
Christian eschatology
Esoteric Christianity
Rosicrucianism | New Galilee (the Sixth Epoch) | [
"Physics"
] | 270 | [
"Spacetime",
"Astrological ages",
"Physical quantities",
"Time"
] |
11,849,804 | https://en.wikipedia.org/wiki/Assisted%20zona%20hatching | Assisted zona hatching is a procedure of assisted reproductive technology, mainly used in IVF, which assists zona hatching. To achieve this a small hole is made in the zona pellucida (mechanically, chemically or by laser) to facilitate hatching. Zona hatching is where the blastocyst gets rid of the surrounding zona pellucida to be able to implant in the uterus.
Efficacy
A systematic review and meta-analysis came to the result that assisted zona hatching is related to increased rates of clinical pregnancy and multiple pregnancy in women with previous repeated failure or frozen-thawed embryos. However, it is unlikely to increase clinical pregnancy rates when performed in fresh embryos transferred to unselected women, to those without poor prognosis or to women of advanced maternal age. Also, overall, there no evidence of a significant difference in live birth rate following assisted hatching compared with no assisted hatching.
Indications
Sometimes, some embryos have a thickened or deformed zona pellucida that makes it difficult for them to come out and, therefore, can lead to implantation failures. To avoid this, this technique can be used. Assisted hatching is not routinely done in all laboratories. It is recommended in some cases:
• Patients of advanced age (37 years or more)
• Implantation failure
• Anomalous zona pellucida (thick, partitioned,...)
• Thawed embryos since vitrification produces a hardening of the zona pellucida.
• Embryos with slow development. For example, when on day 3 they have less than 6 cells.
• To do a blastocyst biopsy
Those embryos biopsied to make PGD (preimplantation genetic diagnosis) will already have the hole made and, therefore, will hatch easily once they reach the stage of expanded blastocysts.
Methods
Mechanical assisted hatching: involves the use of micromanipulation techniques by using a needle. The zona pellucida is pierced with a needle and drilled by friction against a pipette. It is a technique that is rarely used because of the risk it has of damaging the embryo. It is also called "partial zona dissection".
Chemical assisted hatching: involves the use of specialized solutions (mostly acid, e.g. thyroid acid) in order to degrade the zona pellucida. Because it can be toxic for the embryo, it needs to be washed.
"Laser assisted hatching" (LHA): a high energy laser is used to create an opening in the zona pellucida, it is the most precise technique and safe for the embryo but it is the most expensive one.
References
Assisted reproductive technology
Human reproduction | Assisted zona hatching | [
"Biology"
] | 574 | [
"Medical technology stubs",
"Biotechnology stubs",
"Assisted reproductive technology",
"Medical technology"
] |
11,850,008 | https://en.wikipedia.org/wiki/Deluge%20gun | A deluge gun, fire monitor, master stream or deck gun is an aimable controllable high-capacity water jet used for manual firefighting or automatic fire protection systems. Deluge guns are often designed to accommodate foam which has been injected in the upstream piping.
Installation
Deluge guns are often fitted to fire boats, tug boats, and atop large fire trucks for use in manual firefighting, where they can be aimed and operated by one firefighter and are used to deliver water or foam from outside the immediate area of the fire. Deluge guns are sometimes installed in fixed fire protection systems to protect high hazards, such as aviation hangars and helicopter landing pads. Similarly, facilities with highly flammable material such as oil refineries may have permanently-installed deluge guns. Most apparatus-mounted deluge guns can be directed by a single firefighter, compared to a standard fire hose which normally requires several. Deluge guns can be automatically positioned for fixed systems, or may have portable designs. The latter option enables a firefighter to set up the gun to apply water to a blaze, before leaving it in place to attend to other tasks.
Capacity
A deluge gun can discharge per minute or more. A master stream is a fire service term for a water stream of per minute or greater. It is delivered by a master stream device, such as a deck gun, deluge gun, or fire monitor. Master streams are often found at the end of aerial ladders, tele-squirt nozzles, or monitor nozzles. The high pressure that they require renders them unsuitable for handline use.
Risks
A master stream brings with it many risks when used in an urban setting. A master stream should never be fired into an occupied building, as the force could knock down a supporting wall and crush victims. Also, the steam from the high volume of water delivered could cause a blowout or displace oxygen from an enclosed area, creating a risk of asphyxiation.
See also
Standpipe (firefighting)
Water cannon
Water gun
Water salutes, often carried out with deluge guns
References
US Patent for improved mobile fire apparatus
ABS Rules for Steel Vessels 2007 5C.9.11/3 Specific Vessel Types- Chemical Carriers, Fire Protection and Fire Extinction
Fire protection
Firefighting equipment | Deluge gun | [
"Engineering"
] | 470 | [
"Building engineering",
"Fire protection"
] |
11,851,243 | https://en.wikipedia.org/wiki/L%C3%A9o-Pariseau%20Prize | The Léo-Pariseau Prize is a Québécois prize which is awarded annually to a distinguished individual working in the field of biological or health sciences. The prize is awarded by the Association francophone pour le savoir (Acfas), and is named after Léo Pariseau, the first president of Acfas.
The award was inaugurated in 1944 and was the first Acfas prize. Prior to 1980 the prize was awarded to researchers in a large variety of disciplines, before being restricted to biological and health sciences. There are now ten annual prizes for researchers in different disciplines.
Winners
Source: Acfas – Prix de la Recherche Scientifique de l'Acfas – Prix Léo-Pariseau
1944 - Marie-Victorin Kirouac, botany, Université de Montréal
1945 - Paul-Antoine Giguère, chemistry, Université Laval
1946 - Marius Barbeau, ethnology, Université Laval
1947 - Jacques Rousseau, botany and ethnology, Université de Montréal
1948 - Léo Marion, chemistry, University of Ottawa
1949 - Jean Bruchési, history and political science, Université de Montréal
1950 - Louis-Charles Simard, pathology, Université de Montréal
1951 - Cyrias Ouellet, chemistry, Université Laval
1952 - Louis-Paul Dugal, physiology, Université de Montréal
1953 - Guy Frégault, history, Université de Montréal
1954 - Pierre Demers. physics, Université de Montréal
1955 - René Pomerleau, mycology, Université de Montréal
1956 - Marcel Rioux, anthropology, Université de Montréal
1957 - No prize awarded.
1958 - Roger Gaudry, chemistry, Université de Montréal
1959 - Lionel Daviault, entomology
1960 - Marcel Trudel, history, Université Laval
1961 - Raymond Lemieux, chemistry, University of Alberta
1962 - Charles-Philippe Leblond, histology, McGill University
1963 - Lionel Groulx, history, Université de Montréal
1964 - Larkin Kerwin, physics, Université Laval
1965 - Pierre Dansereau, ecology, Université du Québec à Montréal
1966 - Noël Mailloux, psychology, Université de Montréal
1967 - Albéric Boivin, physics, Université Laval
1968 - Léonard-Francis Bélanger, histology, Université de Montréal
1969 - Fernand Dumont, sociology, Université Laval
1970 - Bernard Belleau, biochemistry, Bristol-Myers of Canada
1971 - Édouard Pagé, biology, Université de Montréal
1972 - Louis-Edmond Hamelin, geography, Université Laval
1973 - Camille Sandorfy, chemistry, Université de Montréal
1974 - Antoine D'Iorio, biochemistry, Université d'Ottawa
1975 - Pierre Angersphilosophy, Université de Montréal
1976 - Paul Marmet, physics, Université Laval
1977 - Jacques de Repentigny, microbiology and immunology, Université de Montréal
1978 - Vincent Lemieux, political science, Université Laval
1979 - Pierre Deslongchamps, chemistry, Université de Sherbrooke
1980 - André Barbeau, neurology, Institut de recherches cliniques de Montréal
1981 - Jean-G. Lafontaine, biology, Université Laval
1982 - J.-André Fortin, botany, Université Laval
1983 - Germain Brisson, nutrition, Université Laval
1984 - Wladimir A. Smirnoff, microbiology, Environment Canada
1985 - Louis Legendre, biology, Université Laval
1986 - Marc Cantin, medicine, Université de Montréal
1987 - Guy Lemieux, nephrology, Université de Montréal
1988 - Pierre Borgeat, physiology, Université Laval
1989 - Jules Hardy, neurosurgery, Université de Montréal
1990 - Jacques de Champlain, medicine, Université de Montréal
1991 - Jacques Leblanc, medicine, Université Laval
1992 - Paul Jolicoeur, molecular biology, Institut de recherches cliniques de Montréal
1993 - Albert J. Aguayo, neurology, McGill University
1994 - Emil Skamene, medicine, McGill University
1995 - André Parent, physiology, Université Laval
1996 - Domineco Regoli, pharmacology, Université de Sherbrooke
1997 - Rémi Quirion, neurosciences, McGill University
1998 - Serge Rossignol, neurosciences, Université de Montréal
1999 - Guy Armand Rouleau, neurology, McGill University
2000 - Rima Rozen, human genetics and pediatrics, McGill University
2001 - Nabil G. Seidah, biochemistry and molecular medicine, Institut de recherches cliniques de Montréal
2002 - Graham Bell. biology, McGill University
2003 - Mona Nemer, pharmacology, Université de Montréal
2004 - Jacques Montplaisir, sleep sciences, Université de Montréal
2005 - Laurent Descarries, pathology and cell biology, Université de Montréal
2006 - Michel Bouvier, biochemistry, Université de Montréal
2007 - André Veillette, immunology, Université de Montréal
2008 - Michael Kramer, pediatrics, Université McGill
2009 - Michel J. Tremblay, medical biology, Université Laval
2010 - René Roy, medicinal chemistry, Université du Québec à Montréal
2011 - Claude Perreault, immunology, Université de Montréal
2012 - Julien Doyon, neurosciences, Université de Montréal
2013 - Jean-Pierre Julien, neurodegeneration, Université Laval
2014 - Marc-André Sirard, animal reproduction, Université Laval
2015 - Guy Sauvageau, immunology and oncology, Université de Montréal
2016 - Gustavo Turecki, suicide and neurosciences, McGill University
2017 - Jacques Simard, genetics, Université Laval
2018 - Sylvain Moineau, microbiology, Université Laval
2019 - Sylvain Chemtob, neonatalogy and pharmacology, Université de Montréal
See also
List of biology awards
List of medicine awards
References
Canadian science and technology awards
Awards established in 1944
Medicine awards | Léo-Pariseau Prize | [
"Technology"
] | 1,176 | [
"Science and technology awards",
"Medicine awards"
] |
11,851,594 | https://en.wikipedia.org/wiki/Pseudocercospora%20kaki | Pseudocercospora kaki is a fungal plant pathogen, who causes leaf spot of persimmon. It was originally found on leaves of Diospyros kaki (Oriental persimmon) in Taiwan.
Some examples of other host species are Diospyros hispida, Diospyros lotus (date-plum, Caucasian persimmon), Diospyros texana (Texas persimmon, Mexican persimmon), and Diospyros melanoxylon (Coromandel ebony).
References
Fungal tree pathogens and diseases
Fruit tree diseases
kaki
Fungus species | Pseudocercospora kaki | [
"Biology"
] | 126 | [
"Fungi",
"Fungus species"
] |
11,851,829 | https://en.wikipedia.org/wiki/Krieger%E2%80%93Nelson%20Prize | The Krieger–Nelson Prize is presented by the Canadian Mathematical Society in recognition of an outstanding woman in mathematics. It was first
awarded in 1995. The award is named after Cecilia Krieger and Evelyn Nelson, both known for their contributions to mathematics in Canada.
Recipients
While the award has largely been awarded to a female mathematician working at a Canadian University, it has also been awarded to Canadian-born or -educated women working outside of the country. For example, Cathleen Morawetz, past president of the American Mathematical Society, and a faculty member at the Courant Institute of Mathematical Sciences (a division of New York University) was awarded the Krieger–Nelson Prize in 1997. (Morawetz was educated at the University of Toronto in Toronto, Canada). According to the call for applications, the award winner should be a "member of the Canadian mathematical community".
The recipient of the Krieger–Nelson Prize delivers a lecture to the Canadian Mathematical Society, typically during its summer meeting.
1995 Nancy Reid
1996 Olga Kharlampovich
1997 Cathleen Synge Morawetz
1998 Catherine Sulem
1999 Nicole Tomczak-Jaegermann
2000 Kanta Gupta
2001 Lisa Jeffrey
2002 Cindy Greenwood
2003 Leah Keshet
2004 Not Awarded
2005 Barbara Keyfitz
2006 Penny Haxell
2007 Pauline van den Driessche
2008 Izabella Łaba
2009 Yael Karshon
2010 Lia Bronsard
2011 Rachel Kuske
2012 Ailana Fraser
2013 Chantal David
2014 Gail Wolkowicz
2015 Jane Ye
2016 Malabika Pramanik
2017 Stephanie van Willigenburg
2018 Megumi Harada
2019 Julia Gordon
2020 Sujatha Ramdorai
2021 Anita Layton
2022 Matilde Lalín
2023 Johanna G. Nešlehová
2024 Renate Scheidler
See also
List of mathematics awards
References
External links
Krieger–Nelson Prize, Canadian Mathematical Society.
Awards of the Canadian Mathematical Society
Science awards honoring women
Awards established in 1995
Lists of women scientists
Lists of mathematicians by award
Women in mathematics | Krieger–Nelson Prize | [
"Technology"
] | 411 | [
"Science and technology awards",
"Women in science and technology",
"Science awards honoring women",
"Women in mathematics"
] |
11,851,855 | https://en.wikipedia.org/wiki/Knowledge%20space | In mathematical psychology and education theory, a knowledge space is a combinatorial structure used to formulate mathematical models describing the progression of a human learner. Knowledge spaces were introduced in 1985 by Jean-Paul Doignon and Jean-Claude Falmagne, and remain in extensive use in the education theory. Modern applications include two computerized tutoring systems, ALEKS and the defunct RATH.
Formally, a knowledge space assumes that a domain of knowledge is a collection of concepts or skills, each of which must be eventually mastered. Not all concepts are interchangeable; some require other concepts as prerequisites. Conversely, competency at one skill may ease the acquisition of another through similarity. A knowledge space marks out which collections of skills are feasible: they can be learned without mastering any other skills. Under reasonable assumptions, the collection of feasible competencies forms the mathematical structure known as an antimatroid.
Researchers and educators usually explore the structure of a discipline's knowledge space as a latent class model.
Motivation
Knowledge Space Theory attempts to address shortcomings of standardized testing when used in educational psychometry. Common tests, such as the SAT and ACT, compress a student's knowledge into a very small range of ordinal ranks, in the process effacing the conceptual dependencies between questions. Consequently, the tests cannot distinguish between true understanding and guesses, nor can they identify a student's particular weaknesses, only the general proportion of skills mastered. The goal of knowledge space theory is to provide a language by which exams can communicate
What the student can do and
What the student is ready to learn.
Model structure
Knowledge Space Theory-based models presume that an educational subject can be modeled as a finite set of concepts, skills, or topics. Each feasible state of knowledge about is then a subset of ; the set of all such feasible states is . The precise term for the information depends on the extent to which satisfies certain axioms:
A knowledge structure assumes that contains the empty set (a student may know nothing about ) and itself (a student may have fully mastered ).
A knowledge space is a knowledge structure that is closed under set union: if, for each topic, there is an expert in a class on that topic, then it is possible, with enough time and effort, for each student in the class to become an expert on all those topics simultaneously.
A quasi-ordinal knowledge space is a knowledge space that is also closed under set intersection: if student knows topics and ; and student knows topics and ; then it is possible for another student to know only topic .
A well-graded knowledge space or learning space is a knowledge space satisfying the following axiom: If , then there exists such that In educational terms, any feasible body of knowledge can be learned one concept at a time.
Prerequisite partial order
The more contentful axioms associated with quasi-ordinal and well-graded knowledge spaces each imply that the knowledge space forms a well-understood (and heavily studied) mathematical structure:
A quasi-ordinal knowledge space can be associated with a distributive lattice under set union and set intersection. The name "quasi-ordinal" arises from Birkhoff's representation theorem, which explains that distributive lattices uniquely correspond to partial orders.
A well-graded knowledge space is an antimatroid, a type of mathematical structure that describes certain problems solvable with a greedy algorithm.
In either case, the mathematical structure implies that set inclusion defines partial order on , interpretable as an educational prerequirement: if in this partial order, then must be learned before .
Inner and outer fringe
The prerequisite partial order does not uniquely identify a curriculum; some concepts may lead to a variety of other possible topics. But the covering relation associated with the prerequisite partial does control curricular structure: if students know before a lesson and immediately after, then must cover in the partial order. In such a circumstance, the new topics covered between and constitute the outer fringe of ("what the student was ready to learn") and the inner fringe of ("what the student just learned").
Construction of knowledge spaces
In practice, there exist several methods to construct knowledge spaces. The most frequently used method is querying experts. There exist several querying algorithms that allow one or several experts to construct a knowledge space by answering a sequence of simple questions.
Another method is to construct the knowledge space by explorative data analysis (for example by item tree analysis) from data. A third method is to derive the knowledge space from an analysis of the problem solving processes in the corresponding domain.
References
Cognition
Knowledge representation
Mathematical psychology | Knowledge space | [
"Mathematics"
] | 953 | [
"Applied mathematics",
"Mathematical psychology"
] |
11,851,882 | https://en.wikipedia.org/wiki/Cercospora%20melongenae | Cercospora melongenae is a fungal plant pathogen that causes leaf spot on eggplant (Solanum melongenum). It is a deuteromycete fungus that is primarily confined to eggplant species. Some other host species are Solanum aethiopicum and Solanum incanum. This plant pathogen only attacks leaves of eggplants and not the fruit. It is fairly common among the fungi that infect community gardens and home gardens of eggplant. Generally speaking, Cercospora melongenae attacks all local varieties of eggplants, but is most severe on the Philippine eggplant and less parasitic on a Siamese variety.
Signs and symptoms
Cercospora melongenae is found primarily in warm climates close to the equator. In the US it is prevalent in Hawaii, and could potentially be found in the southern Continental US. Symptoms begin to show on the underside of older, lower leaves first due to the proximity to the soil. They are the first leaves to receive the inoculum. Lesions can be found on leaves, stems and petioles. The lesions appear small and circular at first and later progress to angular and more irregular shapes. The lesions are usually 4-10mm in diameter, and have light to dark tan concentric spots. Spots appear on the upper leaf surface first and eventually progress to the lower side of the leaf. Upon observation in the field with a handheld scope, signs of conidiophores can be seen in the stomata of infected tissue. Conidiophores are typically mid-brown, and straight or slightly flexuous and septate. They are typically 30-150 microns long and 4-7 microns wide. Conidia can also sometimes be seen. Conidia of Cercospora melongenae typically have a truncate base with a somewhat thickened convex scar and a sub-acute apex. The conidia are typically 40-150 microns long and 3-4.5 microns wide, and of 4-14 septate. Later in the disease cycle excessive sporulation can be readily observed in the center of the lesions. Eventually the lesions will dry up and in some cases fall out. The fungi does not affect the fruit, however yield can be impacted due to loss of photosynthetic material.
Disease cycle
Cercospora melongenae exists wholly in its asexual stage; even when grown in culture in the lab, no sexual stage is seen. This means that this disease has an imperfect life cycle, making it of the deuteromycota. Cercospora melongenae overwinters in conidiophores which asexually produce conidia. It survives the winter on lesions of previously infected fruit, plant debris, or simply in the soil. This fungus can survive up to a year in the soil. Conidia is released in the spring when the fungus is ready to infect its host, the eggplant. The conidia disperse by air or wind, or by rain-splash, and are able to infect a suitable host this way. Conidia infect an eggplant host by landing on the lower surface young leaves and entering the leaf through stomata or other natural openings of the plant or wounds on the plant. From infection, there appear to be visible lesions on the leaves. The germ tube of the fungus can enter both closed and open stomata. Multiple germ tubes from various conidia can enter the same stomata. This fungus has the best infection rates among young leaves and has a reduced infection rate of mature leaves. It is thought that the reduced infection rate of mature leaves is due to the saprophytic microflora on the leaves and the anti-fungal compounds produced by the mature leaf. This fungus produces secondary conidia within the same season; this furthers the disease cycle and allows the fungus to infect more plants. Mycelium rapidly develops. Under near perfect conditions, mycelium can develop within twelve hours of infection. The mycelium protects the next generation of conidia and ensures survival through the winter via conidiophores, and the cycle starts again the next season.
Pathogenesis
Cercospora melongenae overwinters in soil or plant debris as conidiophores which then can be dispersed to the plant by rain splash, irrigation water, wind or mechanical transport. The innoculum, conidia, enter through the stomata of the leaves where they germinate and produce more conidia on conidiophores. The conidia must have water or moisture in the form of heavy dew in order to germinate and therefore penetrate the leaf via. the stomata or other natural openings or wounds on the plant. Fungi in the genus Cercospora produce the plant toxin cercosporin, which causes the leaf spot appearance. Cercosporin is a photosensitizing perylenequinone plant toxin that absorbs light energy and converts it into a highly activated state. This activated state then reacts with molecular oxygen to form activated oxygen, which in turn reacts with proteins, lipids, and nucleic acids causing damage or cell death. The fungal spores are not harmed by the production of this toxin because they produce pyridoxine which neutralizes the reaction. While the toxin damages the host cells, conidia is produced and is able to infect the current host or spread to other susceptible hosts in the area.
Environment
Cercospora melongenae enters through breaks in the plant surface on the young leaf host of eggplants, typically through lesions caused by the fungi. Fruiting bodies of the fungus are overall larger when the fungus is able to proliferate during a heavy rain period versus a dry season. The fungus favors wet or moist leaves and high relative humidity for optimal infection. A conducive environment for this fungus is one that is moist and wet, with a fair amount of wind and rain splash for optimal dispersal. This fungi produces larger fruiting structures during a rainy season than during a dry season, indicating the need for a moist or wet environment. Essentially, the amount of moisture in the air is correlated with the sizes of the fruiting structures. In almost all cases and especially in severe cases, signs and symptoms of Cercospora melongenae have already appeared by the beginning of the dry season (or the end of the wet or rainy season). Because Cercospora melongenae is a polycyclic disease and heavily dependent on a moist or wet environment, an extremely heavy rainy season is conducive for larger and greater conidia production and dispersal. What is interesting to note is that in less susceptible eggplant varieties, such as the Siamese variety, signs and symptoms of Cercospora melongenae can be unseen and not appear until at least four weeks after the start of the dry season.
Control and management
Prevention
Proper growing methods, crop rotation, and sanitary procedures are the most effective method of prevention of Cercospora melongenae infection.
Leaf spot is a common disease found in home gardens, and preventing its spread can be done by preventing excessive moisture and humidity accumulation. Ways to reduce relative humidity and dampness include: weed control, irrigating in the morning, avoiding overhead sprinkler irrigation, increasing aeration at base of plants, using covers to minimize dampness.
Crop rotation is also important, as well as the inclusion of diverse intercropping with many other vegetables. Being crop-specific, diversity will help slow down the spread of Cercospora melongenae. Sanitation, such as the use of disease free plants, and the removal of infected plant debris is critical in preventing future infestation. This disease may live in plant debris or soil for at least one year, so burning, or throwing away any infected matter is very important.
Chemical control
There are many fungicides which control Cercospora melongenae including Oils with no added pesticides, and some with. The most common recommended is a Bordeaux mixture, which only needs to be applied once every two weeks. Neem oil, Octanoic acid and copper salt solutions, and various concentrations of Chlorothalonil are all recommended fungicides, as well. Carefully read labels, and laws regarding application regiments and practices.
Fungicides for C. melongenae which are registered in Hawai'i and many other U.S states are:
- Bravo Ultrex® Agricultural Fungicide
- Bravo Weather Stik® Agricultural Fungicide
- Bonide Liquid Copper Fungicide Concentrate
- Bonide Liquid Copper Fungicide Ready to Use
- Bonide Neem Oil Fungicide · Miticide · Insecticide Concentrate
- Garden Safe® Brand Neem Oil Extract Concentrate
- Natural Guard® Neem
- Natural Guard® Copper Soap Liquid Fungicide
- Serenade® Garden Disease Control Concentrate
- Serenade® Garden Disease Control Ready to Spray
Environmental importance
Eggplant is a commonly grown vegetable in home gardens across the United States with an estimated economic value of $1.2 million USD in 1999, and 5,009 acres harvested in 2012.
Because of common garden growing mistakes, Cercospora leaf spot on eggplant is one of the most common fungal infections of eggplant. It is seen to have severe significance on eggplant produce in the Philippines and other southeast Asian tropical islands.
The genus Cercospora may reduce the photosynthetic area of mature leaves by over 75%, and close to 30% in young leaves. While listed as a minor Eggplant Disease in the Philippine Journal of Agriculture, it is an easily avoidable one with proper care and management.
References
melongenae
Vegetable diseases
Fungal plant pathogens and diseases
Fungus species | Cercospora melongenae | [
"Biology"
] | 2,011 | [
"Fungi",
"Fungus species"
] |
11,851,994 | https://en.wikipedia.org/wiki/Real%20Estate%20Transaction%20Standard | Real Estate Transaction Standard (RETS) is a deprecated data standard that was used by the real estate industry in Canada and the United States to facilitate the exchange of data. RETS was launched in 1999 by the National Association of Realtors and related groups.
RETS was originally created to overcome the difficulties presented by the existence of a large number of organizations desiring to share and distribute real estate information with others. Prior to RETS, much of the data exchange was done using the FTP protocol, which did not allow for queries, and required transfer of complete datasets. The inefficiencies of this approach meant that to generate a query such as "new listings since yesterday", the entire dataset had to be downloaded again and compared with a local copy. Rather than basing a solution on alternatives used by other industries to allow for such queries, RETS was created from the ground up as a new framework to attempt to address the need for a common and efficient standard for the exchange of real estate data. Most North American multiple listing service (MLS) data exchange service providers use the RETS protocol. Although the implementation of the protocol has offered some standardization, the field names of the underlying datasets still vary widely between markets.
RETS is a framework that can be adopted by computer systems to receive data from the multiple listing service (MLS) servers, as well as those of other real estate systems, provided they also have software installed designed to communicate using the RETS framework. The National Association of Realtors refers to RETS as a "common language".
Multiple other systems exist which support the secure and standardized transfer of datasets and associated access control requirements in a secure and efficient manner, such as MySQL. These other systems enjoy widespread adoption across most industries, whereas RETS is for one specific industry. RETS is generally not used outside North America.
In 2018, the Real Estate Standards Organization announced that it planned to retire RETS and replace it with the RESO Web API, a RESTful API.
See also
Internet Data Exchange
References
External links
reso.org Real Estate Standards Organization
Real estate in North America
Data interchange standards | Real Estate Transaction Standard | [
"Technology"
] | 442 | [
"Computer standards",
"Data interchange standards"
] |
11,852,565 | https://en.wikipedia.org/wiki/Legal%20aspects%20of%20file%20sharing | File sharing is the practice of distributing or providing access to digital media, such as computer programs, multimedia (audios, photos and/or videos), program files, documents or electronic books/magazines. It involves various legal aspects as it is often used to exchange data that is copyrighted or licensed.
File hosting and sharing
File hosting services may be used as a means to distribute or share files without consent of the copyright holder. In such cases one individual uploads a file to a file hosting service, which others may download. Legal history is documented in case law.
For example, in the case of Swiss-German file hosting service RapidShare, in 2010 the US government's congressional international anti-infringement caucus declared the site a "notorious illegal site", claiming that the site was "overwhelmingly used for the global exchange of illegal movies, music and other copyrighted works". But in the legal case Atari Europe S.A.S.U. v. Rapidshare AG in Germany (Legal case: OLG Düsseldorf, Judgement of 22 March 2010, Az I-20 U 166/09 dated 22 March 2010) the Düsseldorf higher regional court examined claims related to alleged infringing activity and reached the conclusion on appeal that "most people utilize RapidShare for legal use cases" and that to assume otherwise was equivalent to inviting "a general suspicion against shared hosting services and their users which is not justified". The court also observed that the site removes copyrighted material when asked, does not provide search facilities for illegal material, noted previous cases siding with RapidShare, and after analysis the court concluded that the plaintiff's proposals for more strictly preventing sharing of copyrighted material – submitted as examples of anti-file sharing measures RapidShare might have adopted – were found to be "unreasonable or pointless".
In January 2012 the United States Department of Justice seized and shut down the file hosting site Megaupload.com and commenced criminal cases against its owners and others. Their indictment concluded that Megaupload differed from other online file storage businesses, suggesting a number of design features of its operating model as being evidence showing a criminal intent and venture.
Jurisdictions
Australia
A secondary liability case in Australia, under Australian law, was Universal Music Australia Pty Ltd v Sharman License Holdings Ltd [2005] FCA 1242 (5 September 2005). In that case, the Court determined that the Kazaa file sharing system had "authorized" copyright infringement. The claim for damages was subsequently settled out of court.
In the case of AFACT v iiNet which was fought out in the Federal Court, an internet service provider was found not to be liable for the copyright infringement of its users. The case did not, however, create a clear precedent that Australian ISPs could never be held liable for the copyright infringement of their users by virtue of providing an internet connection. AFACT and other major Australian copyright holders have stated their intention to appeal the case, or pursue the matter by lobbying the government to change the Australian law.
Canada
The Copyright Modernization Act was passed in 2012, and came into effect on 2 January 2015. It provides for statutory damages for cases of non-commercial infringement between $100 and $5 000 and damages for commercial infringement from $500 to $20 000.
China
The People's Republic of China is known for having one of the most comprehensive and extensive approaches to observing web activity and censoring information in the world. Popular social networking sites such as Twitter and Facebook cannot be accessed via direct connection by its citizens. Mainland China requires sites that share video files to have permits and be controlled by the state or owned by state. These permits last for three years and will need renewal after that time period. Web sites that violate any rules will be subject to a 5-year ban from providing videos online. One of the country's most used file sharing programs, BTChina got shut down in December 2009. It was shut down by the State Administration of Radio Film and Television for not obtaining a license to legally distribute media such as audio and video files. Alexa, a company that monitors web traffic, claims that BTChina had 80,000 daily users. Being one of the primary file sharing websites for Chinese citizens, this shutdown affected the lives of many internet users in China. China has an online population of 222.4 million people and 65.8% are said to participate in some form of file-sharing on websites.
European Union
On 5 June 2014, the Court of Justice of the European Union (CJEU) ruled that making temporary copies on the user's screen or in the user's cache is not, in itself, illegal. The ruling relates to the British Meltwater case settled on that day.
The judgement of the court states: "Article 5 of Directive 2001/29/EC of the European Parliament and of the Council of 22 May 2001 on the harmonisation of certain aspects of copyright and related rights in the information society must be interpreted as meaning that the copies on the user’s computer screen and the copies in the internet 'cache' of that computer’s hard disk, made by an end-user in the course of viewing a website, satisfy the conditions that those copies must be temporary, that they must be transient or incidental in nature and that they must constitute an integral and essential part of a technological process, as well as the conditions laid down in Article 5(5) of that directive, and that they may therefore be made without the authorisation of the copyright holders."
The Boy Genius Report weblog noted that "As long as an Internet user is streaming copyrighted content online ... it’s legal for the user, who isn’t willfully [sic] making a copy of said content. If the user only views it directly through a web browser, streaming it from a website that hosts it, he or she is apparently doing nothing wrong."
In November 2009, the European Parliament voted on changes to the Telecoms Package. With regard to file-sharing, MEPs agreed to compromise between protecting copyright and protecting user's rights. A European Parliament statement reads "A user's internet access may be restricted, if necessary and proportionate, only after a fair and impartial procedure including the user's right to be heard." EU members were given until May 2011 to implement these changes into their own laws.
Graduated response
In response to copyright violations using peer-to-peer file sharing or BitTorrent the content industry has developed what is known as a graduated response, or three strikes system. Consumers who do not adhere to repeated complaints on copyright infringement, risk losing access to the internet. The content industry has thought to gain the co-operation of internet service providers (ISPs), asking them to provide subscriber information for IP addresses identified by the content industry as engaged in copyright violations. Consumer rights groups have argued that this approach denies consumers the right to due process and the right to privacy. The European Parliament passed a non-binding resolution in April 2008 admonishing laws that would require ISPs to disconnect their users and would prevent individuals from acquiring access to broadband.
In a number of European countries attempts to implement a graduated response have led to court cases to establish under which circumstances an ISP may provide subscriber data to the content industry. In order to pursue those that download copyrighted material the individual committing the infringing must be identified. Internet users are often only identifiable by their Internet Protocol address (IP address), which distinguishes the virtual location of a particular computer. Most ISPs allocate a pool of IP addresses as needed, rather than assigning each computer a never-changing static IP address. Using ISP subscriber information the content industry has thought to remedy copyright infringement, assuming that the ISPs are legally responsible for the end user activity, and that the end user is responsible for all activity connected to his or hers IP address.
In 2005 a Dutch court ordered ISPs in the Netherlands not to divulge subscriber information because of the way the Dutch content industry group had collected the IP addresses (Foundation v. UPC Nederland). According to Dutch law ISPs can only be ordered to provide personal subscriber data if it is plausible that an unlawful act occurred, and if it is shown beyond a reasonable doubt that the subscriber information will identify the person who committed the infringing act. In Germany court specifically considered the right to privacy and in March 2008 the German Federal Constitutional Court ruled that ISPs could only give out IP address subscription information in case of a "serious criminal investigation". The court furthermore ruled that copyright infringement did not qualify as a serious enough offense. Subsequently, in April 2008, the Bundestag (German parliament) approved a new law requiring ISPs to divulge the identity of suspected infringers who infringe on a commercial scale. Similarly, in Sweden, a controversial file sharing bill is awaiting the Riksdag’s approval. The law, which would enter into effect on 1 April 2009, would allow copyright holders to request the IP addresses and names of copyright infringement suspects in order to take legal action against them. The copyright holders, though, should present sufficient evidence of harm to justify the release of information regarding the Internet subscribers. In Italy, the courts established that criminal liability does not extend to file sharing copyrighted material, as long as it is not done for commercial gain. Ruling on a case involving a copyright holder who employed a third party to collect IP addresses of suspected copyright infringers, the Italian Data Protection Authority ruled in February 2008 that the systematic monitoring peer-to-peer activities for the purpose of detecting copyright infringers and suing them is prohibited.
Germany
In Germany, file sharing of copyrighted files, for example through peer-to-peer software like BitTorrent, is illegal. Internet service providers routinely transmit the identity of IP address owners to private lawyer firms who are then able to send "cease and desist" letters often demanding the offender to pay €1,000 fines or more. The GEMA also used to block many YouTube videos.
France
In October 2009, France's highest constitutional court approved the HADOPI law, a "three-strikes law"; however, the law was revoked on 10 July 2013 by the French Government because the punitive penalties imposed on copyright infringers was considered to be disproportionate.
Ireland
In May 2010, Irish internet provider Eircom have announced they will cut off the broadband connection of subscribers suspected of copyright infringement on peer-to-peer file sharing networks. Initially, customers will be telephoned by Eircom to see if they are aware of the unauthorized downloads. When customers are identified for a third time they will lose their internet connection for 7 days, if caught for a fourth time they will lose their internet connection for a year.
Japan
File sharing in Japan is notable for both its size and sophistication. The Recording Industry Association of Japan claims illegal downloads outnumber legal ones 10:1.
The sophistication of Japan's filesharing is due to the sophistication of Japanese anti-filesharing. Unlike most other countries, Copyright infringement is not just a civil offense, but a criminal one, with penalties of up to ten years for uploading and penalties of up to two years for downloading. There is also a high level of Internet service provider cooperation. This makes for a situation where file sharing as practiced in many other countries is quite dangerous.
To counter, Japanese file sharers employ anonymization networks with clients such as Perfect Dark (パーフェクトダーク) and Winny.
Malaysia
In June 2011, the Malaysian Communications and Multimedia Commission has ordered the blocking of several websites including The Pirate Bay and several file-hosting websites via a letter dated 30 May to all Malaysian ISPs for violating Section 41 of the Copyright Act 1987, which deals with pirated content.
Mexico
Mexican law does not currently address non-commercial file sharing, although Mexican legislators have considered increasing penalties for unauthorized file sharing. Broadband usage is increasing in Mexico, and Internet cafes are common. Due to the relative lack of authorized music distribution services in Mexico, filesharing continues to dominate music access. According to the recording industry in 2010, Internet sharing of music dominated approximately 90% of the total music market in Mexico with peer to peer networks the most dominant form of music copyright infringement.
Netherlands
According to Dutch law reproduction of a literary, science, or art work is not considered a violation on the right of the creator or performing artist when all of the following conditions have been met:
The copy has not been made with an (in)direct commercial motive
The copy's purpose is exclusively for own practice, study or use
The number of copies is limited
Such a copy is called a 'thuiskopie' or home copy.
Since 2018, following a decision by the Ministry of Justice, there is an organization which guarantees that artists and rights holders get a compensation for copies of their works made for private use. This compensation is levied indirectly through a surcharge on information carriers such as blank CD's, blank DVD's, MP3 Players, and, since 2013, hard drives and tablets.
North Korea
File sharing in North Korea is done by hand with physical transport devices such as computer disk drives, due to lack of access to the Internet. It is illegal, due to regime attempts to control culture. Despite government repression, file sharing is common, as it is in most other countries.
Because official channels are heavily dominated by government propaganda and outside media is banned, illegally traded files are a unique view into the outside world for North Koreans. The most shared media is from South Korea; k-pop and soap operas.
South Korea
In March 2009, South Korea passed legislation that gave internet users a form of three strikes for unlawful file sharing with the intention of curbing online theft.
This is also known as graduated response.
As the number of cases of unauthorized sharing increases, the proportion of youth involved has increased. As file shares are monitored, they are sent messages instructing them to stop. If their file sharing continues, their internet connection may be disconnected for up to six months.
The force behind this movement is the Korean National Assembly's Committee
on Culture, Sports, Tourism, Broadcasting & Communications (CCSTB&C). With help from local internet service providers, the CCSTB&C have gained
access and formed communication channels to specific file sharing users.
Spain
In a series of cases, Spanish courts have ruled that file sharing for private use is legal.
In 2006, the record industry's attempts to criminalize file sharing were thwarted when Judge Paz Aldecoa declared it legal to download indiscriminately in Spain, if done for private use and without any intent to profit, and the head of the police's technology squad has publicly said "No pasa nada. Podéis bajar lo que queráis del eMule. Pero no lo vendáis." ("It's ok. You can download whatever you want with eMule. But don't sell it."). There have been demonstrations where the authorities have been informed that copyrighted material would be downloaded in a public place, the last of which took place on 20 December 2008. No legal action was taken against the protestors. In another decision from May 2009, a judge ruled in favor of a person engaged in the private, non-commercial file-sharing of thousands of movies, even though the copying was done without the consent of the copyright owners.
The Spanish Supreme Court has ruled that personal data associated with an IP address may only be disclosed in the course of a criminal investigation or for public safety reasons. (Productores de Música de España v. Telefónica de España SAU).
It has been reported that Spain has one of the highest rates of file-sharing in Europe. Over a twelve-month period there were 2.4 billion reported downloads of copyrighted works including music, video games, software and films in Spain. Statistics for 2010 indicate that 30% of the Spanish population uses file-sharing websites, double the European average of 15%.
Record labels would have it that this has had a negative impact on the industry, with investment drying up, according to IFPI head John Kennedy. In 2003, for instance, 10 new Spanish artists appeared in the top 50 album chart, but in 2009 not a single new Spanish artist featured in the same chart. Album sales dropped by two-thirds over a period of five years leading up to 2010. "Spain runs the risk of turning into a cultural desert ... I think it's a real shame that people in authority don't see the damage being done."
However, the Spanish Association of Music Promoters (APM) states that "Music is alive," as despite the decrease in record sales the revenues from concert ticket sales has increased 117% over the last decade, from €69.9 million to €151.1 million in 2008. The number of concerts doubled from 71,045 in 2000 to 144,859 in 2008, and the number of people attending concerts increased from 21.8 million in 2000 to over 33 million in 2008.
Despite the troubles weathered by the entertainment industry, file sharing and torrent websites were ruled legal in Spain in March 2010. The judge responsible for the court ruling stated that "P2P networks are mere conduits for the transmission of data between Internet users, and on this basis they do not infringe rights protected by Intellectual Property laws".
On 20 September 2013, the Spanish government approved new laws that will take effect at the beginning of 2014. The approved legislation will mean that website owners who are earning "direct or indirect profit," such as via advertising links, from pirated content can be imprisoned for up to six years. Peer-to-peer file-sharing platforms and search engines are exempt from the laws.
Since January 2015, Vodafone Spain blocks thepiratebay.org as requested by the Ministry of Interior. And since 29 March 2015 thepiratebay is blocked on multiple URLs from all ISPs[111]
United Kingdom
Around 2010, the UK government's position was that action would help drive the UK’s vital creative and digital sectors to bolster future growth and jobs. According to a 2009 report carried out by the International Federation of the Phonographic Industry 95 per cent of music downloads are unauthorised, with no payment to artists and producers. Market research firm Harris Interactive believed there to be 8.3 million file sharers in the UK. Moreover the BPI claimed that in 1999 UK music purchases totaled £1,113 million but had fallen to £893.8 million in 2008. The Digital Economy Act 2010 received Royal Assent on 9 April 2010. But subsequently its main provisions were never legislatively passed.
Historical situation prior to 2010
Previous cases in the UK have seen internet users receive bills of £2500 for sharing music on the internet.
Digital Economy Act 2010
The Digital Economy Bill proposed that internet service providers (ISPs) issue warnings by sending letters to those downloading copyrighted files without authorization. Following this, the bill proposed that ISPs slow down or even suspend internet access for repeat offenders of unauthorized file sharing. The bill aimed to force internet service providers to disclose the identities of those offenders as well as making conditions for the regulation of copyright licensing. The Digital Economy Bill incorporated a graduated response policy despite the alleged file sharer not necessarily having to be convicted of copyright offences. The bill also introduced fines of up to £50,000 for criminal offences relating to copyright infringement – for example if music is downloaded with intent to sell. The high penalty is considered to be proportionate to the harm caused to UK industries. An appeals process exists whereby the accused can contest the case however, the concern has been expressed that this process will be costly and that, in requiring the individual to prove their innocence, the bill reverses the core principles of natural justice. Similarly, a website may be blocked if it is considered that it has been, is being, or is likely to be used in connection with copyright infringement meaning that a site does not actually have to be involved in copyright infringement – rather intent must be proved.
The Act was seen as controversial, and potentially creating serious repercussions for both file sharers and internet service providers. The bill was met with a mixed response. Geoff Taylor of the BPI claims the bill is vital for the future of creative works in the UK. The Conservative party spokesman for Culture and Media stated that those downloading should be given a criminal record. Conversely, the Liberal Democrat party spokesman for Culture and Media claimed the bill was reckless and dangerous stating that children could unwittingly be file sharing causing an entire family to lose their internet connection. In addition to this, there was concern that hackers may access internet connections to download files and leave the bill payer responsible. Specific concerns raised included:
Providers of public Wi-Fi access is uncertain. Responsibility for breaches could be passed on to the provider due to the difficulty in identifying individual users. The internet provider therefore may risk losing internet access or facing a hefty fine if an infringement of copyright takes place. Many libraries and small cafés for example may find this impossible to adhere to as it would require detailed logging of all those requiring internet access. In libraries in particular this may provide challenges to the profession’s importance of user privacy and could force changes in future policies such as Acceptable Use Policies (AUP). Public libraries utilise AUPs in order to protect creative works from copyright infringement and themselves from possible legal liability. However, unless the AUP is accompanied by the provision of knowledge on how to obey laws it could be seen as unethical, as blame for any breaches is passed to the user.
Hospitality sector - may also be affected by the Digital Economy Act. The British Hospitality Association has stated that hotels would have particular problems in providing details of guest’s internet access to Internet Service Providers and entire hotels may face disconnection. They have also expressed their concern that an individual's actions may lead to such a drastic outcome.
Internet service providers were also hostile towards the bill. TalkTalk stated that suspending access to the internet breached human rights. This view may be shared by many, as a survey carried out by the BBC found that 87% of internet users felt internet access should be the "fundamental right of all people". Certainly, people require access to the internet for many aspects of their life for example shopping, online banking, education, work and even socialising. Furthermore, TalkTalk Director of Regulation, Andrew Heaney has acknowledged that file sharing is a problem but the answer is to educate people and create legal alternatives. Heaney has also argued that disconnected offenders will simply create other user names to hide their identity and continue downloading. TalkTalk has claimed that 80% of youngsters would continue to download regardless of the bill and that internet service providers are being forced to police this without any workable outcomes.
Cable company Virgin Media also criticized the Digital Economy Bill believing it to be heavy handed and likely to alienate customers. Virgin advocated the development of alternative services which people would choose instead of file sharing.
The bill provoked protests in many forms. The Guardian reported that hundreds were expected to march outside the House of Commons on 24 March 2010. Moreover, an estimated 12,000 people sent emails to their MPs, through the citizen advocacy organization 38 degrees. 38 degrees objected to the speed with which the bill was rushed through parliament, without proper debate, due to the imminent dissolution of parliament prior to a general election. In October 2009 TalkTalk launched its Don't Disconnect Us campaign asking people to sign a petition against the proposal to cut off the internet connections of those accused of unauthorized file sharing. By November 2009 the petition had almost 17,000 signatories and by December had reached over 30,000. The Pirate Party in the UK called for non-commercial file sharing to be legalized. Formed in 2009 and intending to enter candidates in the 2010 UK general election, the Pirate Party advocates reform to copyright and patent laws and a reduction in government surveillance.
The Code which would implement these sections of the Act was never passed into law by Parliament, and no action was taken on it after around 2013.
Digital Economy Act 2017
The Digital Economy Act 2017 updates the anti-infringement provisions of existing laws, creates or updates criminal copyright breach provisions, and provides for a wider range of sentencing for criminal infringement.
United States
In Sony Corp. v. Universal Studios, 464 U.S. 417 (1984), the Supreme Court found that Sony's new product, the Betamax (the first mass-market consumer videocassette recorder), did not subject Sony to secondary copyright liability because it was capable of substantial non-infringing uses. Decades later, this case became the jumping-off point for all peer-to-peer copyright infringement litigation.
The first peer-to-peer case was A&M Records v. Napster, 239 F.3d 1004 (9th Cir. 2001). Here, the 9th Circuit considered whether Napster was liable as a secondary infringer. First, the court considered whether Napster was contributorily liable for copyright infringement. To be found contributorily liable, Napster must have engaged in "personal conduct that encourages or assists the infringement." The court found that Napster was contributorily liable for the copyright infringement of its end-users because it "knowingly encourages and assists the infringement of plaintiffs' copyrights." The court analyzed whether Napster was vicariously liable for copyright infringement. The standard applied by the court was whether Napster "has the right and ability to supervise the infringing activity and also has a direct financial interest in such activities." The court found that Napster did receive a financial benefit, and had the right and ability to supervise the activity, meaning that the plaintiffs demonstrated a likelihood of success on the merits of their claim of vicarious infringement. The court denied all of Napster's defenses, including its claim of fair use.
The next major peer-to-peer case was MGM v. Grokster, 545 U.S. 913 (2005). In this case, the Supreme Court found that even if Grokster was capable of substantial non-infringing uses, which the Sony court found was enough to relieve one of secondary copyright liability, Grokster was still secondarily liable because it induced its users to infringe.
It is important to note the concept of blame in cases such as these. In a pure P2P network there is no host, but in practice most P2P networks are hybrid. This has led groups such as the RIAA to file suit against individual users, rather than against companies. The reason that Napster was subject to violation of the law and ultimately lost in court was because Napster was not a pure P2P network but instead maintained a central server which maintained an index of the files currently available on the network.
Around the world in 2006, an estimated five billion songs, equating to approximately 38,000 years in music were swapped on peer-to-peer websites, while 509 million songs were purchased online. The same study which estimated these findings also found that artists that had an online presence ended up retaining more of the profits rather than the music companies.
In November 2009, the U.S. House of Representatives introduced the Secure Federal File Sharing Act, which would, if enacted, prohibit the use of peer-to-peer file-sharing software by U.S. government employees and contractors on computers used for federal government work. The bill has died with the adjournment of 111th Congress.
Copyright law
A copyright in the United States consists of the exclusive rights enumerated under 17 USC 106. When having to do with pictures, music, literature or video, these exclusive rights include:
1. The right to reproduce or redistribute the picture, music, lyrics, text, video, or images of a video.
2. The right to distribute the picture, music, lyrics, text, video, or images of a video.
3. The right to produce derivative works of the copyrighted work.
4. The right to perform the work publicly.
5. The right to display the work publicly.
6. The right to transmit the work through the use of radio or digital transition.
In summary, these exclusive rights cover the reproduction, adaptation, publication, performance, and display of a copyrighted work (subject to limitations such as fair use).
Anyone who violates the exclusive rights of copyright has committed copyright infringement, whether or not the work has been registered at the copyright office. If an infringement has occurred, the copyright owner has a legal right to sue the infringer for violating the terms of their copyright. The monetary value of the lawsuit can be whatever a jury decides is acceptable.
In the case of file sharing networks, companies claim that peer-to-peer file sharing enables the violation of their copyrights. File sharing allows any file to be reproduced and redistributed indefinitely. Therefore, the reasoning is that if a copyrighted work is on a file sharing network, whoever uploaded or downloaded the file is liable for violating the copyright because they are reproducing the work without the authorization of the copyright holder or the law.
Primary infringement liability
The fundamental question, "what use can a P2P file-sharing network's customers make of the software and of copyrighted materials without violating copyright law", has no answer at this time, as there has been almost no dispositive decision-making on the subject.
This issue has received virtually no appellate attention, the sole exception being BMG Music v. Gonzalez, a decision of the U.S. Court of Appeals for the Seventh Circuit, which held that where a defendant has admitted downloading and copying song files from other users in the P2P network without permission of the copyright holders, she cannot claim that such copying is a "fair use". Since Gonzalez involves a defendant who had admitted to actual copying and downloading of songs from other unauthorized users, it is of limited applicability in contested cases, in that it relates solely to the reproduction right in 17 USC 106(1), and has no bearing on the 17 USC 106(3) distribution right.
A series of cases dealing with the RIAA's "making available" theory has broad implications, not only for the subject of P2P file sharing but for the Internet at large. The first to receive a great deal of attention was Elektra v. Barker, an RIAA case against Tenise Barker, a Bronx nursing student. Ms. Barker moved to dismiss the complaint, contending, among other things, that the RIAA's allegation of "making available" did not state any known claim under the Copyright Act. The RIAA countered with the argument that even without any copying, and without any other violation of the record companies' distribution rights, the mere act of "making available" is a copyright infringement, even though the language does not appear in the Copyright Act, as a violation of the "distribution" right described in 17 USC 106(3). Thereafter, several amicus curiae were permitted to file briefs in the case, including the MPAA, which agreed with the RIAA's argument, and the Electronic Frontier Foundation (EFF), the U.S. Internet Industry Association (USIIA), and the Computer & Communications Industry Association (CCIA), which agreed with Ms. Barker. The US Department of Justice submitted a brief refuting one of the arguments made by EFF, but did not take any position on the RIAA's "making available" argument, noting that it had never prosecuted anyone for "making available". The Elektra v. Barker case was argued before Judge Kenneth M. Karas in Manhattan federal court on 26 January 2007, and decided on 31 March 2008.
The decision rejected the RIAA's "making available" theory but sustained the legal sufficiency of the RIAA's pleading of actual distribution and actual downloading. Additionally, the Court suggested to the RIAA that it might want to amend its complaint to include a claim for "offering to distribute for purposes of distribution", but gave no guidance on what type of evidence would be required for an "offer". The Court's suggestion that merely "offering" to distribute could constitute a violation of the Act has come under attack from William Patry, the author of the treatise Patry on Copyright.
Three other decisions, also rejecting the RIAA's "making available" theory, came from more unexpected sources.
The Barker decision was perhaps rendered anticlimactic by the decision of Judge Janet Bond Arterton, from the District of Connecticut, handed down six weeks earlier, in Atlantic v. Brennan, rejecting the RIAA's application for a default judgment. Brennan, like Barker, rejected the RIAA's "making available" theory, but unlike Barker it found the RIAA's specificity on the other issues to be insufficient, and it rejected the conceptual underpinnings upon which Judge Karas based his "offer to distribute" idea.
And Barker was perhaps overshadowed by the decision of Judge Gertner, rendered the same day as the Barker decision, in quashing a subpoena served on Boston University to learn the identity of BU students, in London-Sire v. Doe 1. Here too the Court rejected the RIAA's "making available" theory, but here too—like Atlantic but unlike Elektra – also rejected any possible underpinning for an "offer to distribute" theory.
And then came the decision of the District Judge Neil V. Wake, in the District of Arizona, in Atlantic v. Howell. This 17-page decision – rendered in a case in which the defendant appeared pro se (i.e., without a lawyer) but eventually received the assistance of an amicus curiae brief and oral argument by the Electronic Frontier Foundation—was devoted almost exclusively to the RIAA's "making available" theory and to the "offer to distribute" theory suggested by Judge Karas in Barker. Atlantic v. Howell strongly rejected both theories as being contrary to the plain wording of the Copyright Act. The Court held that "Merely making a copy available does not constitute distribution....The statute provides copyright holders with the exclusive right to distribute "copies" of their works to the public "by sale or other transfer of ownership, or by rental, lease, or lending." 17 U.S.C. ...106(3). Unless a copy of the work changes hands in one of the designated ways, a "distribution" under ...106(3) has not taken place." The Court also expressly rejected the 'offer to distribute' theory suggested in Barker, holding that "An offer to distribute does not constitute distribution".
The next critical decision was that in Capitol v. Thomas, which had received a great deal of media attention because it was the RIAA's first case to go to trial, and probably additional attention due to its outsized initial jury verdict. The RIAA had prevailed upon the trial judge to give the jurors an instruction which adopted its "making available" theory, over the protestations of the defendant's lawyer. Operating under that instruction, the jury returned a $222,000 verdict over $23.76 worth of song files. Almost a year after the jury returned that verdict, however, District Judge Michael J. Davis set the verdict aside, and ordered a new trial, on the ground that his instruction to the jurors—that they did not need to find that any files were actually distributed in order to find a violation of plaintiffs' distribution right—was a "manifest error of law". The Judge's 44-page decision agreed with Howell and London-Sire and rejected so much of Barker as intimated the existence of a viable "offer to distribute" theory.
There may be indications that the RIAA has been jettisoning its "making available" theory. In a San Diego, California, case, Interscope v. Rodriguez, where the Judge dismissed the RIAA's complaint as "conclusory", "boilerplate", "speculation", the RIAA filed an amended complaint which contained no reference at all to "making available". In subsequent cases, the RIAA's complaint abandoned altogether the "making available" theory, following the model of the Interscope v. Rodriguez amended complaint.
In its place, it is apparently adopting the "offer to distribute" theory suggested by Judge Karas. In the amended complaint the RIAA filed in Barker, it deleted the "making available" argument—as required by the judge—but added an "offer to distribute" claim, as the judge had suggested. It remains to be seen if it will follow that pattern in other cases.
Secondary infringement liability
Secondary liability, the possible liability of a defendant who is not a copyright infringer but who may have encouraged or induced copyright infringement by another, has been discussed generally by the United States Supreme Court in MGM v. Grokster, which held in essence that secondary liability could only be found where there has been affirmative encouragement or inducing behavior. On remand, the lower court found Streamcast, the maker of Morpheus software, to be liable for its customers' copyright infringements, based upon the specific facts of that case.
Under US law "the Betamax decision" (Sony Corp. of America v. Universal City Studios, Inc.), holds that copying "technologies" are not inherently illegal, if substantial non-infringing use can be made of them. Although this decision predated the widespread use of the Internet, in MGM v. Grokster, the U.S. Supreme Court acknowledged the applicability of the Betamax case to peer-to-peer file sharing, and held that the networks could not be liable for merely providing the technology, absent proof that they had engaged in "inducement."
In 2006 the RIAA initiated its first major post-Grokster, secondary liability case, against LimeWire in Arista Records LLC v. Lime Group LLC, where the United States District Court for the Southern District of New York held that LimeWire induced copyright infringement and granted a permanent injunction against LimeWire.
Electronic Frontier Foundation
The Electronic Frontier Foundation (EFF) seeks to protect and expand digital rights through litigation, political lobbying, and public awareness campaigns. The EFF has vocally opposed the RIAA in its pursuit of lawsuits against users of file sharing applications and supported defendants in these cases. The foundation promotes the legalization of peer-to-peer sharing of copyrighted materials and alternative methods to provide compensation to copyright holders.
In September 2008 the organization marked the 5th 'anniversary' of the RIAA's litigation campaign by publishing a highly critical, detailed report, entitled "RIAA v. The People: Five Years Later", concluding that the campaign was a failure.
Reported suspension of RIAA litigation campaign
Several months later, it was reported that the RIAA was suspending its litigation campaign, followed by a report that it had fired the investigative firm SafeNet (formerly MediaSentry) operating on its behalf. Some of the details of the reports, including claims that the RIAA had actually stopped commencing new lawsuits months earlier, and that its reason for doing so was that it had entered into tentative agreements with Internet service providers to police their customers, proved to be either inaccurate or impossible to verify and RIAA's claim not to have filed new cases "for months" was false.
Effects
A study ordered by the European Union found that illegal downloading may lead to an increase in overall video game sales because newer games charge for extra features or levels. The paper concluded that piracy had a negative financial impact on major blockbuster films. The study relied on self-reported data about game purchases and use of illegal download sites. Pains were taken to remove effects of false and misremembered responses.
Notable cases
EU
Atari Europe S.A.S.U. v. Rapidshare AG (Germany)
OiNK's Pink Palace (England)
USA
The AACS encryption key controversy of 2007
Flava Works Inc. v. Gunter - appeal case which analyzed contributory infringement in the context of linking to infringing material and social bookmarking.
Megaupload legal case
MGM v. Grokster
Sony Corp. v. Universal City Studios (The Betamax decision)
Sweden
The Pirate Bay trial
Singapore
Odex's actions against file-sharing
See also
Legal aspects of computing
Peer-to-peer file sharing
Sony BMG copy protection rootkit scandal
Copyright Directive (disambiguation)
Shared resource
Timeline of file sharing
Legal issues with BitTorrent
Don't Copy That Floppy
Torrent poisoning
Countries blocking access to The Pirate Bay
References
Computer law
Copyright law by country
Digital rights
File sharing | Legal aspects of file sharing | [
"Technology"
] | 8,358 | [
"Computer law",
"Computing and society"
] |
11,853,055 | https://en.wikipedia.org/wiki/Biodiversity%20Outcomes%20Framework | Canada's Biodiversity Outcomes Framework was approved by Ministers responsible for Environment, Forests, Parks, Fisheries and Aquaculture, and Wildlife in October 2006. It has been developed further to the Canadian Biodiversity Strategy, an implementation measure required under Article 6 of the United Nations Convention on Biological Diversity.
Criticism of the Framework
The Framework has been developed from the Canadian Biodiversity Strategy, which has been criticized as having a tendency to focus on species and to assign less importance to other scales of biodiversity from the genetic to the ecosystem level.
See also
Criticisms of the biodiversity paradigm
References
External links
Convention on Biological Diversity
Biodiversity Convention Office
Environment Canada
Ecology organizations
Environment and Climate Change Canada
Convention on Biological Diversity | Biodiversity Outcomes Framework | [
"Biology"
] | 133 | [
"Convention on Biological Diversity",
"Biodiversity"
] |
11,853,200 | https://en.wikipedia.org/wiki/Raman%20Parimala | Raman Parimala (born 21 November 1948) is an Indian mathematician known for her contributions to algebra. She is the Arts & Sciences Distinguished Professor of mathematics at Emory University. For many years, she was a professor at Tata Institute of Fundamental Research (TIFR), Mumbai.
She was on the Mathematical Sciences jury for the Infosys Prize 2019—2022 and was on the Abel prize selection Committee 2021–2023.
Background
Parimala was born and raised in Tamil Nadu, India. She studied in Saradha Vidyalaya Girls' High School and Stella Maris College at Chennai. She received her M.Sc. from Madras University (1970) and Ph.D. from the
University of Mumbai (1976); her advisor was R. Sridharan from TIFR.
In 1987, she won the highest science award in India: The Shanti Swarup Bhatnagar Prize.
She is a fellow of the Indian National Science Academy (New Delhi).
Selected publications
Failure of a quadratic analogue of Serre's conjecture, Bulletin of the AMS, vol. 82, 1976, pp. 962–964
Quadratic spaces over polynomial extensions of regular rings of dimension 2, Mathematische Annalen, vol. 261, 1982, pp. 287–292
Galois cohomology of the Classical groups over fields of cohomological dimension≦2, E Bayer-Fluckiger, R Parimala - Inventiones mathematicae, 1995 - Springer
Hermitian analogue of a theorem of Springer, R Parimala, R. Sridharan, V Suresh - Journal of Algebra, 2001 - Elsevier
Classical groups and the Hasse principle, E Bayer-Fluckiger, R Parimala - Annals of Mathematics, 1998 - jstor.org
Honors
On National Science Day in 2020, Smriti Irani, head of the Ministry of Women and Child Development of the Government of India, announced the establishment of chairs at institutes across India in the names of Raman Parimala and other ten Indian women scientists.
Parimala was an invited speaker at the International Congress of Mathematicians in Zurich in 1994 and gave a talk Study of quadratic forms — some connections with geometry . She gave a plenary address Arithmetic of linear algebraic groups over two dimensional fields at the Congress in Hyderabad in 2010.
Fellow of the Indian Academy of Sciences
Fellow of Indian National Science Academy
Bhatnagar Award in 1987
Honorary doctorate from the University of Lausanne in 1999
Srinivasa Ramanujan Birth Centenary Award in 2003.
TWAS Prize for Mathematics (2005).
Fellow of the American Mathematical Society (2012)
Notes
External links
Home page at Emory
Parimala's biography in the Agnes Scott College database of women mathematicians
1948 births
Emory University faculty
Algebraists
Living people
Tamil scholars
Tata Institute of Fundamental Research alumni
Fellows of the American Mathematical Society
Scientists from Tamil Nadu
University of Madras alumni
Indian women science writers
20th-century Indian women writers
20th-century Indian mathematicians
20th-century Indian women scientists
21st-century Indian mathematicians
21st-century Indian women scientists
21st-century Indian women writers
Women writers from Tamil Nadu
TWAS laureates
20th-century Indian non-fiction writers
21st-century Indian non-fiction writers
20th-century Indian women mathematicians
21st-century Indian women mathematicians
Recipients of the Shanti Swarup Bhatnagar Award in Mathematical Science | Raman Parimala | [
"Mathematics"
] | 676 | [
"Algebra",
"Algebraists"
] |
11,853,249 | https://en.wikipedia.org/wiki/Hyper%20Search | Hyper Search is a method of link analysis for search engines. It was created by Italian researcher Massimo Marchiori.
Bibliography
Massimo Marchiori, "The Quest for Correct Information on the Web: Hyper Search Engines", Proceedings of the Sixth International World Wide Web Conference (WWW6), 1997.
Sergey Brin and Lawrence Page, "The anatomy of a large-scale hypertextual Web search engine", Proceedings of the Seventh International World Wide Web Conference (WWW7), 1998.
See also
PageRank
Spamdexing
PR
References
Internet search | Hyper Search | [
"Technology"
] | 113 | [
"Computing stubs",
"World Wide Web stubs"
] |
11,853,271 | https://en.wikipedia.org/wiki/Biodiversity%20Convention%20Office | Canada's Biodiversity Convention Office (BCO) serves as National Focal Point for the United Nations Convention on Biological Diversity and the Canadian Biodiversity Strategy. BCO also provides a leadership role in the Biodiversity Conservation Working Group of the Commission for Environmental Cooperation and in the Conservation of Arctic Flora and Fauna (CAFF) working group of the Arctic Council.
The BCO was established by Environment Canada in September 1991 to coordinate Canadian involvement in the negotiations of the Convention. Following Canada's ratification of the Convention in December 1992, attention shifted to development of a Canadian response. Under the guidance of the BCO, a Federal-Provincial-Territorial Working Group was charged by the Canadian Council of Ministers of the Environment with developing the Canadian Biodiversity Strategy. In 1996, all jurisdictions signed a statement of commitment to use the Strategy as a guide to implementing the Convention in Canada. In 2005, Ministers instructed the Federal-Provincial-Territorial Working Group to develop a corresponding outcomes-based framework for guiding and monitoring implementation of the Canadian Biodiversity Strategy. This Biodiversity Outcomes Framework was approved by Ministers responsible for Environment, Forests, Parks, Fisheries and Aquaculture, and Wildlife in October 2006.
The BCO plays a policy coordinating, catalysing and facilitating role in national efforts to define Canada's response to the Convention and National Strategy. It operates through a network of contacts within and outside government. At the federal level, an Interdepartmental Committee on Biodiversity provides advice and guidance on domestic and international policy issues. The Federal/Provincial/Territorial Biodiversity Working Group focuses on national biodiversity issues. BCO also works with indigenous groups to enable their participation in meeting the objectives of the Convention and the Canadian Biodiversity Strategy. It also undertakes a variety of public education activities, helping to create awareness and training tools for national implementation of the Canadian Biodiversity Strategy.
See also: Criticisms of the biodiversity paradigm
References
External links
Convention on Biological Diversity
Biodiversity Convention Office
Environment Canada
Environment of Canada
Environment and Climate Change Canada
Biodiversity | Biodiversity Convention Office | [
"Biology"
] | 392 | [
"Biodiversity"
] |
11,853,438 | https://en.wikipedia.org/wiki/Canadian%20Biodiversity%20Strategy | The Canadian Biodiversity Strategy has been prepared in response to Canada's obligations as a party to the United Nations Convention on Biological Diversity. The Strategy has been developed as a guide to the implementation of the Biodiversity Convention in Canada.
Recognition of the worldwide impact of the decline of biodiversity inspired the global community to negotiate the United Nations Convention on Biological Diversity. The Canadian delegation participated in the negotiations, the Prime Minister signed the Convention at the Earth Summit in June 1992 and, in December 1992, Canada ratified it. Prior ratifying parties included Mauritius, Maldives, and Monaco.
One of the key obligations for parties that have ratified the Convention is to prepare a national strategy.
Elements of the Strategy
The Strategy contains guiding principles supporting a vision of society that lives sustainably, and contains a framework for action to support sustainable development as part of international efforts to implement the Convention on Biological Diversity. The Strategy goals are related to conservation, education, support, and collaboration.
In 2015, Canada adopted 19 targets to fulfill its obligations under the treaty. The first was to conserve at least 17% of terrestrial area and inland water, and 10% of coastal and marine areas, through "networks of protected areas and other effective area-based conservation measures." By the end of 2019, Canada was not on track to meeting its first target, having only conserved 12.1% of its terrestrial area (land and freshwater).
Criticism of the Strategy
Although biodiversity exists at many levels, from genetics to communities to ecosystems, and varies depending on type and organization, most conservation plans - the Canadian Biodiversity Strategy included - tend to focus on tangible, easily measured, visible aspects of biodiversity: species.
See also
Biodiversity
Convention on Biological Diversity
Canada's Biodiversity Convention Office
Canadian Biodiversity Information Network
Biodiversity Outcomes Framework
Criticisms of the biodiversity paradigm
References
External links
Convention on Biological Diversity
Biodiversity Convention Office
Environment Canada
Environment of Canada
Environment and Climate Change Canada
Convention on Biological Diversity | Canadian Biodiversity Strategy | [
"Biology"
] | 380 | [
"Convention on Biological Diversity",
"Biodiversity"
] |
11,853,832 | https://en.wikipedia.org/wiki/Cercospora%20apii | Cercospora apii is a fungal plant pathogen, who causes leaf spot on celery, and found on other plants, including Impatiens. Since the genus Cercospora is one of the largest and most heterogeneous genera of hyphomycetes, numerous species described from diverse hosts and locations are morphologically indistinguishable from C. apii and subsequently are referred to as C. apii sensu lato.
See also
Cercospora apii f.sp. clerodendri
References
apii
Fungal plant pathogens and diseases
Eudicot diseases
Fungus species | Cercospora apii | [
"Biology"
] | 129 | [
"Fungi",
"Fungus species"
] |
11,854,184 | https://en.wikipedia.org/wiki/Netgear%20MP101 | The Netgear MP101 was the first of a series of digital media receivers by Netgear.
Family history
The Netgear MP101's family also includes other devices such as the MP115, the EVA700 and, the EVA8000.
Appearance
The Netgear MP101 is a small brushed silver unit that can provide a link between a PC-based MP3 collection and a conventional hi-fi.
Concept
The MP101 requires a UPnP AV media server to provide access to digital media, while some other units (and the later EVA8000) can read from a Windows share directly (or a NAS device).
Netgear does not manufacture the devices itself, but they are produced instead by a third-party company and then marketed as a Netgear product.
Implementation
The MP101 is based on the ARM9 Marvell Libertas 88W8510H system-on-a-chip and has 8 MB of DRAM. Netgear licensed the ARM MP3 decoder software for use with the device.
The MP101 runs the open-source eCos real-time operating system. Netgear made the source code available online.
External links
MP101 review (December 20, 2004)
ARM press release: NetGear Builds Innovative Wireless MP3 Player Around ARM Powered SOC From Marvell (March 16, 2004)
MP101
Internet audio players | Netgear MP101 | [
"Technology"
] | 289 | [
"Netgear",
"Wireless networking"
] |
11,855,027 | https://en.wikipedia.org/wiki/Cashline | Cashline is the name and brand of the Automated Teller Machine (ATM) network in the United Kingdom run by the Royal Bank of Scotland.
History
Its beginnings date back to 1967 when the Royal Bank installed its first ATM in its offices in the West End of Edinburgh. Initially the service offered only basic deposit services to a small select number of customers, but by 1977 the familiar cash withdrawal service to current account holders was launched under the Cashline name.
By 1980, the Cashline network had become the busiest ATM network in the world in terms of how frequently each machine is used and how much money is taken out each time. Cashline ATMs up until the mid-1980s were usually of De La Rue or IBM-Diebold manufacture, before being progressively replaced by NCR machines. Cashline is a member of the LINK network, and in 1997 took the step of being available to all cardholders, irrespective of the ATM network their own particular bank belonged.
Coverage
Cashline ATMs are also exclusively found in branches of Tesco supermarkets all over the United Kingdom, operating under the Tesco Personal Finance banner, but with a small "Cashline" below the Tesco lettering.
The word cashline has become a generic name in Scotland used to describe a cash machine.
External links
ATMs Resources
Royal Bank of Scotland
Automated teller machines | Cashline | [
"Engineering"
] | 270 | [
"Automation",
"Automated teller machines"
] |
11,855,137 | https://en.wikipedia.org/wiki/Tetrabromobisphenol%20A | Tetrabromobisphenol A (TBBPA) is a brominated flame retardant. The compound is a white solid (not colorless), although commercial samples appear yellow. It is one of the most common flame retardants.
Production and use
TBBPA is produced by the reaction of bromine with bisphenol A. Most commercial TBBPA products consist of a mixture that differ in the degree of bromination with the formula C15H16−xBrxO2 where x = 1 to 4. Its fire-retarding properties correlate with its bromine content. The annual consumption in Europe has been estimated as 6200 tons in 2004.
TBBPA is mainly used as a reactive component of polymers, meaning that it is incorporated into the polymer backbone. It is used to prepare fire-resistant polycarbonates by replacing some bisphenol A. A lower grade of TBBPA is used to prepare epoxy resins, used in printed circuit boards.
Toxicity
A study was published by the European Food Safety Authority (EFSA) in December 2011 on the exposure of TBBPA and its derivatives in food. The study, which examined at 344 food samples from the fish and other seafood food group, concluded that “current dietary exposure to TBBPA in the European Union does not raise a health concern.” EFSA also determined that “additional exposure, particularly of young children, to TBBPA from house dust is unlikely to raise a health concern”.
Some studies suggest that TBBPA may be an endocrine disruptor and immunotoxicant. As an endocrine disruptor, TBBPA may interfere with both estrogens and androgens. Further, TBBPA structurally mimics the thyroid hormone thyroxin (T4) and can bind more strongly to the transport protein transthyretin than T4 does, likely interfering with normal T4 activity. TBBPA likely also suppresses immune responses by inhibiting expression of CD25 receptors on T cells, preventing their activation, and by reducing natural killer cell activity.
A 2013 literature review on TBBPA concludes that TBBPA does not produce “adverse effects that might be considered to be related to disturbances in the endocrine system”. Therefore, in accordance with internationally accepted definitions, TBBPA should not be considered an “endocrine disruptor”. Furthermore, TBBPA is rapidly excreted in mammals and therefore does not have a potential for bioaccumulation. Measured concentrations of TBBPA in house dust, human diet and human serum samples are very low. Daily intakes of TBBPA in humans were estimated to not exceed a few ng/kg bw/day. Exposures of the general population are also well below the derived-no-effect-levels (DNELs) derived for endpoints of potential concern in REACH.
TBBPA degrades to bisphenol A and to TBBPA dimethyl ether, and experiments in zebrafish (Danio rerio) suggest that during development, TBBPA may be more toxic than either BPA or TBBPA dimethyl ether.
Occurrence
TBBPA emits can be found in trace concentration in the hydrosphere, soil, and sediments. It also occurs in sewage sludge and house dust. TBBPA has been the subject of an eight-year evaluation under the EU Risk Assessment procedure which reviewed over 460 studies. The Risk Assessment was published on the EU Official Journal in June 2008. The conclusions of the Risk Assessment were confirmed by the European Commission SCHER Committee (Scientific Committee on Health and Environmental Risks). TBBPA has been registered under REACH.
See also
Dinitrobisphenol A
Further reading
Early work on bromination of BPA:
References
External links
BSEF, TBBPA Factsheet
BSEF, industry page on TBBPA: Environmental aspects
Flame retardants
Bromoarenes
Phenols
Suspected endocrine disruptors
2,2-Bis(4-hydroxyphenyl)propanes
IARC Group 2A carcinogens | Tetrabromobisphenol A | [
"Chemistry"
] | 854 | [
"Endocrine disruptors",
"Suspected endocrine disruptors"
] |
11,855,225 | https://en.wikipedia.org/wiki/Mycosphaerella%20bolleana | Mycosphaerella bolleana is a fungal plant pathogen.
See also
List of Mycosphaerella species
References
External links
New Zealand Fungi: Mycosphaerella bolleana
bolleana
Fungal plant pathogens and diseases
Fungi described in 1920
Fungus species | Mycosphaerella bolleana | [
"Biology"
] | 56 | [
"Fungi",
"Fungus species"
] |
11,855,520 | https://en.wikipedia.org/wiki/LG%20VX9400 | The LG VX9400 is a mobile phone manufactured by LG Electronics. The CDMA radio is supplied by Verizon Wireless in the United States. It was one of the first two phones on the market to support live mobile TV broadcasts using Qualcomm's MediaFLO technology (along with the Samsung SCH-U620). The unique design of the QVGA display allows it to swing up into landscape orientation for TV viewing. Other key features of the VX9400 includes stereo Bluetooth, an SD card slot, digital music player, EVDO high-speed data connectivity, and speakerphone.
The phone was also featured in the 2008 movie Iron Man, as the phone Tony Stark used to communicate with Obadiah about the successful presentation of a Stark Industries Jericho missile. The phone was also a significant focus in the movie Picture This starring Ashley Tisdale.
It is compatible with BitPim 1.0 and later to upload ringtones, transfer wallpapers and pictures, and to back up SMS messages, the phone book/contact list and the calendar. The current available software version is v03 and should be updated at your local Verizon store.
Specifications/Features
References
VX9400 | LG VX9400 | [
"Technology"
] | 255 | [
"Mobile technology stubs",
"Mobile phone stubs"
] |
11,856,314 | https://en.wikipedia.org/wiki/Knowledge%20Engineering%20Environment | Knowledge Engineering Environment (KEE) is a frame-based development tool for expert systems. It was developed and sold by IntelliCorp, and was first released in 1983. It ran on Lisp machines, and was later ported to Lucid Common Lisp with the CLX library, an X Window System (X11) interface for Common Lisp. This version was available on several different UNIX workstations.
On KEE, several extensions were offered:
Simkit, a frame-based simulation library
KEEconnection, database connection between the frame system and relational databases
In KEE, frames are called units. Units are used for both individual instances and classes. Frames have slots and slots have facets. Facets can describe, for example, a slot's expected values, its working value, or its inheritance rule. Slots can have multiple values. Behavior can be implemented using a message passing model.
KEE provides an extensive graphical user interface (GUI) to create, browse, and manipulate frames.
KEE also includes a frame-based rule system. In the KEE knowledge base, rules are frames. Both forward chaining and backward chaining inference are available.
KEE supports non-monotonic reasoning through the concepts of worlds. Worlds allow providing alternative slot-values of frames. Through an assumption-based truth or reason maintenance system, inconsistencies can be detected and analyzed.
ActiveImages allows graphical displays to be attached to slots of Units. Typical examples are buttons, dials, graphs, and histograms. The graphics are also implemented as Units via KEEPictures, a frame-based graphics library.
See also
Expert system
Frame language
Inference engine
IntelliCorp (software)
Knowledge base
Knowledge-based system
Knowledge representation
References
External links
An Assessment of Tools for Building Large Knowledge-Based Systems
Knowledge engineering
Knowledge representation
Common Lisp (programming language) software | Knowledge Engineering Environment | [
"Engineering"
] | 385 | [
"Systems engineering",
"Knowledge engineering"
] |
3,022,744 | https://en.wikipedia.org/wiki/Direct%20image%20functor | In mathematics, the direct image functor is a construction in sheaf theory that generalizes the global sections functor to the relative case. It is of fundamental importance in topology and algebraic geometry. Given a sheaf F defined on a topological space X and a continuous map f: X → Y, we can define a new sheaf f∗F on Y, called the direct image sheaf or the pushforward sheaf of F along f, such that the global sections of f∗F is given by the global sections of F. This assignment gives rise to a functor f∗ from the category of sheaves on X to the category of sheaves on Y, which is known as the direct image functor. Similar constructions exist in many other algebraic and geometric contexts, including that of quasi-coherent sheaves and étale sheaves on a scheme.
Definition
Let f: X → Y be a continuous map of topological spaces, and let Sh(–) denote the category of sheaves of abelian groups on a topological space. The direct image functor
sends a sheaf F on X to its direct image presheaf f∗F on Y, defined on open subsets U of Y by
This turns out to be a sheaf on Y, and is called the direct image sheaf or pushforward sheaf of F along f.
Since a morphism of sheaves φ: F → G on X gives rise to a morphism of sheaves f∗(φ): f∗(F) → f∗(G) on Y in an obvious way, we indeed have that f∗ is a functor.
Example
If Y is a point, and f: X → Y the unique continuous map, then Sh(Y) is the category Ab of abelian groups, and the direct image functor f∗: Sh(X) → Ab equals the global sections functor.
Variants
If dealing with sheaves of sets instead of sheaves of abelian groups, the same definition applies. Similarly, if f: (X, OX) → (Y, OY) is a morphism of ringed spaces, we obtain a direct image functor f∗: Sh(X,OX) → Sh(Y,OY) from the category of sheaves of OX-modules to the category of sheaves of OY-modules. Moreover, if f is now a morphism of quasi-compact and quasi-separated schemes, then f∗ preserves the property of being quasi-coherent, so we obtain the direct image functor between categories of quasi-coherent sheaves.
A similar definition applies to sheaves on topoi, such as étale sheaves. There, instead of the above preimage f−1(U), one uses the fiber product of U and X over Y.
Properties
Forming sheaf categories and direct image functors itself defines a functor from the category of topological spaces to the category of categories: given continuous maps f: X → Y and g: Y → Z, we have (gf)∗=g∗f∗.
The direct image functor is right adjoint to the inverse image functor, which means that for any continuous and sheaves respectively on X, Y, there is a natural isomorphism:
.
If f is the inclusion of a closed subspace X ⊆ Y then f∗ is exact. Actually, in this case f∗ is an equivalence between the category of sheaves on X and the category of sheaves on Y supported on X. This follows from the fact that the stalk of is if and zero otherwise (here the closedness of X in Y is used).
If f is the morphism of affine schemes determined by a ring homomorphism , then the direct image functor f∗ on quasi-coherent sheaves identifies with the restriction of scalars functor along φ.
Higher direct images
The direct image functor is left exact, but usually not right exact. Hence one can consider the right derived functors of the direct image. They are called higher direct images and denoted Rq f∗.
One can show that there is a similar expression as above for higher direct images: for a sheaf F on X, the sheaf Rq f∗(F) is the sheaf associated to the presheaf
,
where Hq denotes sheaf cohomology.
In the context of algebraic geometry and a morphism of quasi-compact and quasi-separated schemes, one likewise has the right derived functor
as a functor between the (unbounded) derived categories of quasi-coherent sheaves. In this situation, always admits a right adjoint . This is closely related, but not generally equivalent to, the exceptional inverse image functor , unless is also proper.
See also
Proper base change theorem
References
, esp. section II.4
Sheaf theory
Theory of continuous functions | Direct image functor | [
"Mathematics"
] | 999 | [
"Functions and mappings",
"Mathematical structures",
"Theory of continuous functions",
"Mathematical objects",
"Sheaf theory",
"Topology",
"Mathematical relations",
"Functors",
"Category theory"
] |
3,022,839 | https://en.wikipedia.org/wiki/H-Bahn | The H-Bahn (abbreviation for , German for 'hanging railway') in Dortmund and Düsseldorf (there known as "Sky train") is a driverless passenger suspension railway system. The system was developed by Siemens, who call the project SIPEM (SIemens PEople Mover).
Two installations exist, one at the Dortmund university campus, the other at the Düsseldorf Airport. While Siemens is no longer actively marketing the system, and will no longer carry out turnkey projects, new installations are still possible in collaboration with the Dortmund operating company.
Since 2011 Air Train International has been marketing the system in China and there are proposals to build lines in Shanghai and Wenzhou. A number of other Chinese cities are also studying the system.
Technical description
The cabins are centrally controlled and do not need a driver. The system can operate on a schedule or on-demand, whereby a passenger requests a carriage by pushing a button, similar to summoning an elevator. The maximum speed is . The system allows forking by a system of switches in the carrier.
Suspension and propulsion
The carrier is a hollow rectangular box girder with a slit in the bottom through which the cabin is suspended at the running gear, whose two axles carry the load with a rubber wheel on both sides providing both suspension and propulsion. Two wheels run horizontally along the top and bottom of the interior side walls of the carrier box, providing horizontal guidance. Thus, the designation as a monorail system is to be taken with a grain of salt, meaning just that there is a single axis of suspension.
400-volt three-phase current is taken from four conductors at the side wall. Above those, a cable provides continuous wireless data connection between the train and the control center.
All contact between the suspended cabin and the fixed system is enclosed in the interior of the carrier box, protected from the elements. In this sense, the SIPEM suspension system is similar to the one used by the earlier SAFEGE system (which was developed in France and which is used on two networks in Japan), but is much narrower, both the carrier box as well as the open slit for the suspension.
The cabin is suspended below two motorized bogies, which are enclosed in the carrier girder. Each bogie is equipped with two electric motors, providing a peak motive power of .
Each running gear is equipped with two motors, which are connected in parallel via their armature circuits
(4-pole separately-excited DC machine with contraflexure poles).
Operating voltage 3 x 400 V, 50 Hz
Nominal power of motors 4 x
Range of revolutions per minute 0-3,290 rpm
Nominal torque 90 Nm
Nominal propulsive force
Maximum propulsive force
Regular acceleration
Regular deceleration
Emergency deceleration >
Nominal speed
Positioning accuracy ±
Noise level (measured at at distance) < 65 dB/A
Cabin
Each cabin is long (, including couplers), wide and high. The interior height for standing passengers is . It has two wide automatic sliding doors at each side. The Dortmund cabin provides seating for 16 and standing room for 29 passengers, while the Düsseldorf airport version provides space for 15 and 32, respectively.
The cabin shell weighs . The complete car weighs , with bogies weighing each. It can carry a useful load of up to and has a maximum gross weight of .
Switching
Switching is done with the help of the horizontal guiding wheels, where short blades on both sides of the common section of the carrier move as a canal of the same width as the carrying box to the left or right, while a long blade between the two forking guideways moves right or left to provide the horizontal guidance into the intended direction.
History
In 1973, the Federal Ministry made DM 22 million (€11,250,000) available for the research and promotion of this system. A test line was opened on 21 July 1975 in Düsseldorf by the former transport minister Hans Matthoefer with a length of 180 metres (approx. 200 yards). In 1976, the system was extended by 1.5 km (a little less than a mile).
Dortmund
The first publicly funded overhead railway has run since 1984 at the University of Dortmund, where it initially just connected the north and south campuses with a single line. However, many stations have 2 platforms with a track either side permitting carriages to pass each other in opposite directions. This stretch was opened on 2 May 1984 by Dr. Heinz Riesenhuber, and comprised of track and two trains. The cost was approximately DM 24,000,000 (€12,270,000), of which 75% was funded by the German Federal Government, 20% by the state of North Rhine-Westphalia and 5% by the city of Dortmund.
The longest span between support pillars is 38.5 metres (126.3 ft), where it crosses the university road, which bisects the two campuses. Just beyond the road the H-Bahn crosses through a nature reserve at its maximum elevation of about 16 metres (approx. 50 feet) above ground. In order to prevent passengers getting close to the track at stations, there are platform edge doors between the platform and the track. As soon as the vehicles arrive in the station, doors in the partition open automatically, along with the train car doors.
In 1993, following a three-year construction period, a new 900 m (0.56 mile) long branch was opened, along with two new stations, one in Eichlinghofen and another at the S-Bahn station at Dortmund university. This construction included technology considered to be the first of its kind in Germany. The existing system was renovated, and equipped with technology which allowed determining the train's location with a much higher precision — within 3 cm (1.2 in). These changes allowed for a higher speed, and trains can now also follow each other more closely. Three new carriages were supplied by Siemens. An extension into the nearby technology park was opened on 19 December 2003, which means the current network, including this final extension, has a length of 3.162 km (approx. 2 miles). The building of this section cost around €15,500,000.
Line 1 operates between the Technology Park and Eichlinghofen, and during the day carriages arrive every ten minutes, stopping at the university and the S-Bahn stop, where there is a connection every twenty minutes to Dortmund city centre, and Bochum. Two trains serve line 1.
Line 2 is the original line between the North and South campuses of the university, and is served by a third train. A reserve fourth vehicle is available, and there is also a maintenance vehicle.
Further extensions to the H-Bahn network were being considered, but were not cost-effective enough:
Between the university and the central bus and train station of Dortmund.
Eastward from the university, as far as to the Märkische Strasse, southeast of downtown Dortmund.
Düsseldorf Airport
A nearly identical monorail system called SkyTrain transfers passengers at Düsseldorf Airport, which opened on 1 July 2002 after almost six years of construction. The system links Terminal C and Terminal A+B with the long-term parking facility and the long-distance train station along a twin line.
See also
Wuppertal Schwebebahn
Skybus Metro
External links
SIPEM Dortmund and Düsseldorf with technical descriptions
Monorails.org on SIPEM
Die H-Bahn an der Uni Dortmund (in German)
Presentation of H-Bahn for a project in Moscow (in Russian) with videos and photo gallery
References
SIPEM people movers
Rail services in North Rhine-Westphalia
Dortmund
University people mover systems
People mover systems in Germany
Monorails in Germany | H-Bahn | [
"Engineering"
] | 1,546 | [
"Siemens Mobility projects",
"SIPEM people movers"
] |
3,022,936 | https://en.wikipedia.org/wiki/Asphaltene | Asphaltenes are molecular substances that are found in crude oil, along with resins, aromatic hydrocarbons, and saturates (i.e. saturated hydrocarbons such as alkanes). The word "asphaltene" was coined by Jean-Baptiste Boussingault in 1837 when he noticed that the distillation residue of some bitumens had asphalt-like properties. Asphaltenes in the form of asphalt or bitumen products from oil refineries are used as paving materials on roads, shingles for roofs, and waterproof coatings on building foundations.
Composition
Asphaltenes consist primarily of carbon, hydrogen, nitrogen, oxygen, and sulfur, as well as trace amounts of vanadium and nickel. The C:H ratio is approximately 1:1.2, depending on the asphaltene source. Asphaltenes are defined operationally as the n-heptane ()-insoluble, toluene ()-soluble component of a carbonaceous material such as crude oil, bitumen, or coal. Asphaltenes have been shown to have a distribution of molecular masses in the range of 400 u to 1500 u, but the average and maximum values are difficult to determine due to aggregation of the molecules in solution.
Analysis
The molecular structure of asphaltenes is difficult to determine because the molecules tend to stick together in solution. These materials are extremely complex mixtures containing hundreds or even thousands of individual chemical species. Asphaltenes do not have a specific chemical formula: individual molecules can vary in the number of atoms contained in the structure, and the average chemical formula can depend on the source. Although they have been subjected to modern analytical methods, including SARA, mass spectrometry, electron paramagnetic resonance and nuclear magnetic resonance, the exact molecular structures are difficult to determine. Given this limitation, asphaltenes are composed mainly of polyaromatic carbon ring units with oxygen, nitrogen, and sulfur heteroatoms, combined with trace amounts of heavy metals, particularly chelated vanadium and nickel, and aliphatic side chains of various lengths. Many asphaltenes from crude oils around the world contain similar ring units, as well as polar and non-polar groups, which are linked together to make highly diverse large molecules.
Asphaltene after heating have been subdivided as: nonvolatile (heterocyclic N and S species), and, volatile (paraffin + olefins, benzenes, naphthalenes, phenanthrenes, several others). Speight reports a simplified representation of the separation of petroleum into the following six major fractions: volatile saturates, volatile aromatics, nonvolatile saturates, nonvolatile aromatics, resins and asphaltenes. He also reports arbitrarily defined physical boundaries for petroleum using carbon-number and boiling point.
Geochemistry
Asphaltenes are today widely recognised as dispersed, chemically altered fragments of kerogen, which migrated out of the source rock for the oil, during oil catagenesis. Asphaltenes had been thought to be held in solution in oil by resins (similar structure and chemistry, but smaller), but recent data shows that this is incorrect. Indeed, it has recently been suggested that asphaltenes are nanocolloidally suspended in crude oil and in toluene solutions of sufficient concentrations. In any event, for low surface tension liquids, such as alkanes and toluene, surfactants are not necessary to maintain nanocolloidal suspensions of asphaltenes.
The nickel to vanadium ratio of asphaltenes reflect the pH and Eh conditions of the paleo-depositional environment of the source rock for oil (Lewan, 1980;1984), and this ratio is, therefore, in use in the petroleum industry for oil-oil correlation and for identification of potential source rocks for oil exploration.
Occurrence
Heavy oils, oil sands, bitumen and biodegraded oils (as bacteria cannot assimilate asphaltenes, but readily consume saturated hydrocarbons and certain aromatic hydrocarbon isomers – enzymatically controlled) contain much higher proportions of asphaltenes than do medium-API oils or light oils. Condensates are virtually devoid of asphaltenes.
Measurement
Because the ratio of electron spins per gram is constant for a particular species of asphaltene then the quantity of asphaltene in an oil can be determined by measuring its paramagnetic signature (EPR). Measuring the EPR signature of the oil at the wellhead as the oil is produced then gives a direct indication of whether the amount of asphaltene is changing (e.g. because of precipitation or sloughing in the tubing below).
In addition, asphaltene aggregation, precipitation or deposition can sometimes be predicted by modeling or machine learning methods and can be measured in the laboratory using imaging methods or filtration.
Production problems
Asphaltenes impart high viscosity to crude oils, negatively impacting production. Furthermore, the variable asphaltene concentration in crude oils within individual reservoirs creates a myriad of production problems.
Heat exchanger fouling
Asphaltenes are known to be one of the largest causes of fouling in the heat exchangers of the crude oil distillation preheat train. They are present within micelles in crude oil, which can be broken down by reaction with paraffins under high temperature. Once the protective micelle has been removed polar asphaltenes agglomerate and are transported to the tube walls, where they can stick and form a foulant layer.
Asphaltene removal
Chemical treatments for removing asphaltene include:
Solvents
Dispersants/solvents
Oil/dispersants/solvents
The dispersant/solvent approach is used for removing asphaltenes from formation minerals. Continuous treating may be required to inhibit asphaltene deposition in the tubing. Batch treatments are common for dehydration equipment and tank bottoms. There are also asphaltene precipitation inhibitors that can be used by continuous treatment or squeeze treatments.
See also
Tholin
References
External links
An in-depth article on asphaltenes from OilfieldWiki.com, the oilfield encyclopedia
Article regarding asphaltene fouling by Irwin A. Wiehe
Asphaltene Aggregation from Crude Oils and Model Systems Studied by High-Pressure NIR Spectroscopy (Source : American Chemical Society)
A comprehensive website about asphaltene and its role in petroleum fouling by Prof. GA Mansoori at the Univ. of Illinois at Chicago
Petroleum production
Asphalt | Asphaltene | [
"Physics",
"Chemistry"
] | 1,312 | [
"Amorphous solids",
"Asphalt",
"Unsolved problems in physics",
"Chemical mixtures"
] |
3,022,963 | https://en.wikipedia.org/wiki/Discriminant%20of%20an%20algebraic%20number%20field | In mathematics, the discriminant of an algebraic number field is a numerical invariant that, loosely speaking, measures the size of the (ring of integers of the) algebraic number field. More specifically, it is proportional to the squared volume of the fundamental domain of the ring of integers, and it regulates which primes are ramified.
The discriminant is one of the most basic invariants of a number field, and occurs in several important analytic formulas such as the functional equation of the Dedekind zeta function of K, and the analytic class number formula for K. A theorem of Hermite states that there are only finitely many number fields of bounded discriminant, however determining this quantity is still an open problem, and the subject of current research.
The discriminant of K can be referred to as the absolute discriminant of K to distinguish it from the relative discriminant of an extension K/L of number fields. The latter is an ideal in the ring of integers of L, and like the absolute discriminant it indicates which primes are ramified in K/L. It is a generalization of the absolute discriminant allowing for L to be bigger than Q; in fact, when L = Q, the relative discriminant of K/Q is the principal ideal of Z generated by the absolute discriminant of K.
Definition
Let K be an algebraic number field, and let OK be its ring of integers. Let b1, ..., bn be an integral basis of OK (i.e. a basis as a Z-module), and let {σ1, ..., σn} be the set of embeddings of K into the complex numbers (i.e. injective ring homomorphisms K → C). The discriminant of K is the square of the determinant of the n by n matrix B whose (i,j)-entry is σi(bj). Symbolically,
Equivalently, the trace from K to Q can be used. Specifically, define the trace form to be the matrix whose (i,j)-entry is
TrK/Q(bibj). This matrix equals BTB, so the square of the discriminant of K is the determinant of this matrix.
The discriminant of an order in K with integral basis b1, ..., bn is defined in the same way.
Examples
Quadratic number fields: let d be a square-free integer, then the discriminant of is
An integer that occurs as the discriminant of a quadratic number field is called a fundamental discriminant.
Cyclotomic fields: let n > 2 be an integer, let ζn be a primitive nth root of unity, and let Kn = Q(ζn) be the nth cyclotomic field. The discriminant of Kn is given by
where is Euler's totient function, and the product in the denominator is over primes p dividing n.
Power bases: In the case where the ring of integers has a power integral basis, that is, can be written as OK = Z[α], the discriminant of K is equal to the discriminant of the minimal polynomial of α. To see this, one can choose the integral basis of OK to be b1 = 1, b2 = α, b3 = α2, ..., bn = αn−1. Then, the matrix in the definition is the Vandermonde matrix associated to αi = σi(α), whose determinant squared is
which is exactly the definition of the discriminant of the minimal polynomial.
Let K = Q(α) be the number field obtained by adjoining a root α of the polynomial x3 − x2 − 2x − 8. This is Richard Dedekind's original example of a number field whose ring of integers does not possess a power basis. An integral basis is given by {1, α, α(α + 1)/2} and the discriminant of K is −503.
Repeated discriminants: the discriminant of a quadratic field uniquely identifies it, but this is not true, in general, for higher-degree number fields. For example, there are two non-isomorphic cubic fields of discriminant 3969. They are obtained by adjoining a root of the polynomial or , respectively.
Basic results
Brill's theorem: The sign of the discriminant is (−1)r2 where r2 is the number of complex places of K.
A prime p ramifies in K if and only if p divides ΔK .
Stickelberger's theorem:
Minkowski's bound: Let n denote the degree of the extension K/Q and r2 the number of complex places of K, then
Minkowski's theorem: If K is not Q, then |ΔK| > 1 (this follows directly from the Minkowski bound).
Hermite–Minkowski theorem: Let N be a positive integer. There are only finitely many (up to isomorphisms) algebraic number fields K with |ΔK| < N. Again, this follows from the Minkowski bound together with Hermite's theorem (that there are only finitely many algebraic number fields with prescribed discriminant).
History
The definition of the discriminant of a general algebraic number field, K, was given by Dedekind in 1871. At this point, he already knew the relationship between the discriminant and ramification.
Hermite's theorem predates the general definition of the discriminant with Charles Hermite publishing a proof of it in 1857. In 1877, Alexander von Brill determined the sign of the discriminant. Leopold Kronecker first stated Minkowski's theorem in 1882, though the first proof was given by Hermann Minkowski in 1891. In the same year, Minkowski published his bound on the discriminant. Near the end of the nineteenth century, Ludwig Stickelberger obtained his theorem on the residue of the discriminant modulo four.
Relative discriminant
The discriminant defined above is sometimes referred to as the absolute discriminant of K to distinguish it from the relative discriminant ΔK/L of an extension of number fields K/L, which is an ideal in OL. The relative discriminant is defined in a fashion similar to the absolute discriminant, but must take into account that ideals in OL may not be principal and that there may not be an OL basis of OK. Let {σ1, ..., σn} be the set of embeddings of K into C which are the identity on L. If b1, ..., bn is any basis of K over L, let d(b1, ..., bn) be the square of the determinant of the n by n matrix whose (i,j)-entry is σi(bj). Then, the relative discriminant of K/L is the ideal generated by the d(b1, ..., bn) as {b1, ..., bn} varies over all integral bases of K/L. (i.e. bases with the property that bi ∈ OK for all i.) Alternatively, the relative discriminant of K/L is the norm of the different of K/L. When L = Q, the relative discriminant ΔK/Q is the principal ideal of Z generated by the absolute discriminant ΔK . In a tower of fields K/L/F the relative discriminants are related by
where denotes relative norm.
Ramification
The relative discriminant regulates the ramification data of the field extension K/L. A prime ideal p of L ramifies in K if, and only if, it divides the relative discriminant ΔK/L. An extension is unramified if, and only if, the discriminant is the unit ideal. The Minkowski bound above shows that there are no non-trivial unramified extensions of Q. Fields larger than Q may have unramified extensions: for example, for any field with class number greater than one, its Hilbert class field is a non-trivial unramified extension.
Root discriminant
The root discriminant of a degree n number field K is defined by the formula
The relation between relative discriminants in a tower of fields shows that the root discriminant does not change in an unramified extension.
Asymptotic lower bounds
Given nonnegative rational numbers ρ and σ, not both 0, and a positive integer n such that the pair (r,2s) = (ρn,σn) is in Z × 2Z, let αn(ρ, σ) be the infimum of rdK as K ranges over degree n number fields with r real embeddings and 2s complex embeddings, and let α(ρ, σ) = liminfn→∞ αn(ρ, σ). Then
,
and the generalized Riemann hypothesis implies the stronger bound
There is also a lower bound that holds in all degrees, not just asymptotically: For totally real fields, the root discriminant is > 14, with 1229 exceptions.
Asymptotic upper bounds
On the other hand, the existence of an infinite class field tower can give upper bounds on the values of α(ρ, σ). For example, the infinite class field tower over Q() with m = 3·5·7·11·19 produces fields of arbitrarily large degree with root discriminant 2 ≈ 296.276, so α(0,1) < 296.276. Using tamely ramified towers, Hajir and Maire have shown that α(1,0) < 954.3 and α(0,1) < 82.2, improving upon earlier bounds of Martinet.
Relation to other quantities
When embedded into , the volume of the fundamental domain of OK is (sometimes a different measure is used and the volume obtained is , where r2 is the number of complex places of K).
Due to its appearance in this volume, the discriminant also appears in the functional equation of the Dedekind zeta function of K, and hence in the analytic class number formula, and the Brauer–Siegel theorem.
The relative discriminant of K/L is the Artin conductor of the regular representation of the Galois group of K/L. This provides a relation to the Artin conductors of the characters of the Galois group of K/L, called the conductor-discriminant formula.
Notes
References
Primary sources
Secondary sources
Further reading
Algebraic number theory | Discriminant of an algebraic number field | [
"Mathematics"
] | 2,278 | [
"Algebraic number theory",
"Number theory"
] |
3,023,067 | https://en.wikipedia.org/wiki/Scaled%20Composites%20ARES | The Scaled Composites ARES is a demonstrator aircraft built by Scaled Composites. ARES is an acronym for Agile Responsive Effective Support.
Development
In 1981, U.S. Army Aviators Jim Kreutz and Milo Burroughs undertook a study for a low cost battlefield attack aircraft (LCBAA), as they felt the close air support aircraft available were inadequate to support the U.S. Army operations. They decided that a fixed-wing aircraft with excellent maneuvering capabilities at very low altitudes and resistance to stall would be necessary.
Burt Rutan joined their study to design an aircraft to meet the requirements with a two-phase program. The first phase was the preliminary design of LCBAA, while in the second phase the Long EZ aircraft was modified to serve as a technology demonstrator. The original layout was of a low wing canard configuration, aircraft powered by a pusher turboprop, and built around a 30 mm Gatling gun capable of destroying light armored vehicles. It was decided that as much military hardware as possible would be used in the design.
When a Pentagon official promised that they would evaluate his aircraft if he built it, he built a demonstrator aircraft in 1986.
By this time the aircraft had changed significantly. It retained the general configuration, but now had a single Pratt & Whitney Canada JT15D-5 turbofan engine rather than a turboprop as the propeller was vulnerable to debris kicked up by the nosewheel.
A GAU-12/U 25 mm rotary barreled cannon was mounted in the aircraft to the right of the nose in a concave recess under the cockpit. The concave recess trapped gun exhaust gases, creating a pressure buildup in the recess which pushing the aircraft's nose to the left, cancelled the recoil of the large cannon, which otherwise pushed the nose to the right. To prevent exhaust gases from the gun entering the engine intake and reducing engine performance, the engine intake was located on the left side of the nose, opposite the cannon making the aircraft asymmetric. Thrust was redirected to the centerline via a series of ducts, which also reduced the infrared signature.
After Beechcraft sold Scaled Composites back to Rutan, he chose to complete the project with company funds. This aircraft was renamed ARES, and first flew on February 19, 1990, piloted by Scaled Composites test pilot Doug Shane. Since then it has flown more than 250 hours, and met its original design specifications for performance and range. In 1991 under US Air Force contract, the ARES 25 mm cannon was installed and during testing the cannon performed well but the ARES remains a private project.
After an appearance in the movie Aces: Iron Eagle III as a fictional Me 263 fighter, the aircraft has become a commercially available research test bed. The aircraft was stored in December 2000 at the Mojave Spaceport until Scaled Composites became a Northrop Grumman subsidiary and flown again on March 7, 2008.
Design
The ARES is of canard configuration to enable safer flight at low altitude. The foreplane provides pitch control and is designed so that it reaches critical angle of attack sooner than the main wings, protecting the aircraft from stall while full roll control is retained. The foreplane has a wingspan of 19.2 feet (5.85 m) and is unusual in being swept 7 degrees forward from its attachment point behind the cockpit.
The main wing has a span of 35 feet (10.7 m) and a reference area of , not including the strakes. It is swept aft 16 degrees at the leading edge. The strakes are swept 49 degrees at the leading edge. These strakes, combined with a wet wing center-section area, form the bulk of the 2,200 lb (1000 kg, approximately ) fuel capacity. The wing has conventional ailerons on the outboard trailing edge, and spoil-flaps (similar to the dive-brake flap) on the inboard trailing edges. The ailerons are actuated by push-rods, and the spoil-flaps are hydraulically operated.
Directional stability is provided by twin boom-mounted fins, each of . area. Each has a cable-actuated rudder at its trailing edge. The rudder actuation system also drives the full-time mechanical nosewheel steering for ground operations.
The engine inlet is another major unique feature of ARES. Since gun gas ingestion posed significant problems in other aircraft development programs (like A-10), the configuration of ARES was designed to avoid this problem: the engine inlet is entirely contained on the left side of the aircraft, and the gun is installed on the right side. The inlet has a circular cross section, and is straight into the fan face. The engine is mounted slightly transversely in the fuselage, with an 8-degree misalignment from the aircraft's longitudinal axis.
The engine exhaust is turned back to the longitudinal axis by a curved composite tailpipe. A composite tailpipe was to help get the gun recoil reaction closer to the aircraft lateral center of gravity (CG) location, the gun is sub-merged as deeply as practical into the right side of the fuselage. Also, the fuselage is not centered about the aircraft centerline, but is offset to the left by . This results in the firing barrel of the gun being only about from the lateral CG. This minimizes the yaw movement caused by the recoil of the gun.
The aircraft fuselage is almost completely made of fiberglass composite material installed over the foam core. The fabrication technique of composite aircraft fuselages has been perfected by Scaled Composites in previous aircraft.
To assure a low cost and high reliability of the components ARES primarily includes off-the-shelf aircraft systems. The engine is the Pratt and Whitney Canada JT15D with 2,900 lb (13.2 kN) of thrust at sea level. The hydraulic system, used for spoiler flaps and landing gear actuation, uses a Piper Malibu hydraulic pump, which operates at . Instrumentation for the demonstrator consists mainly of standard general aviation equipment. In addition there is a head-up display which currently displays only a fixed reticle to aim the gun but is capable of displaying the complete data range of an F-16. The pilot sits in a Universal Propulsion Company SIIIS-3ER ejection seat with zero-zero capability.
The fuel system consists of auxiliary wing tanks feeding an armored, fuselage-mounted main tank, which sits just forward of the engine and behind the firewall. The main tank can feed the engine in all attitudes. This tank is continuously refilled from the main wing tanks with no fuel management duties required of the pilot. By feeding the main tank from the two auxiliary wing tanks, the size of the fuel tank in the fuselage was effectively halved, creating a large space behind the pilot empty of any tanks or other aircraft systems. This bay had no dedicated function on the demonstrator, but was intended to be left available for any additional equipment which the Army might wish to install in the production version.
The main flight controls are completely mechanical and the engine has a backup mechanical fuel control so the aircraft can retain control even if the electrical system fails. The controls were specially designed to minimize the forces on the stick.
Besides the GAU-12 gun, there are additional pylons to carry another ordnance (Hydra 70 FFAR, for example).
The ARES has very good turning performance as a result of low wing loading. Its turn rate is 32 degrees per second at 6G and 36 degrees per second at 7G (the structure is limited to 8G). The corner speed is 210 kn (390 km/h) the stall speed is 78 kn (145 km/h).
Due to high fuel volume and good cruising efficiency the aircraft can have a range of 1200 nautical miles (2200 km) at altitude and long endurance.
Specifications (Scaled Composites 151 ARES)
See also
Textron AirLand Scorpion
IML Addax, similar project from New Zealand
British Aerospace P.1233-1 Saba
PZL-230 Skorpion
References
"Airdata File: Scaled Composites ARES". Air International, Vol. 38, No. 5. May 1990. ISSN 0306-5634. p. 266.
Lambert, Mark. Jane's All The World's Aircraft 1993–94. Coulsdon, UK: Jane's Data Division, 1993. .
The Complete Encyclopedia of World Aircraft by David Donald
External links
Scaled Composites company ARES web page
Photos of ARES and other Rutan aircraft
More photos of ARES (in Russian)
YouTube Demo video narrated by Burt Rutan
1990s United States experimental aircraft
ARES
Aircraft with retractable tricycle landing gear
Canard aircraft
Asymmetrical aircraft
Single-engined jet aircraft
Low-wing aircraft
Twin-boom aircraft
Twin-tail aircraft | Scaled Composites ARES | [
"Physics"
] | 1,796 | [
"Asymmetrical aircraft",
"Symmetry",
"Asymmetry"
] |
3,023,194 | https://en.wikipedia.org/wiki/Attic | An attic (sometimes referred to as a loft) is a space found directly below the pitched roof of a house or other building. It is also known as a sky parlor or a garret. Because they fill the space between the ceiling of a building's top floor and its slanted roof, attics are known for being awkwardly-shaped spaces with difficult-to-reach corners and often exposed rafters.
While some attics are converted into bedrooms, home offices, or attic apartments complete with windows and staircases, most remain difficult to access, and are usually entered using a loft hatch and ladder. Attics help control temperatures in a house by providing a large mass of slowly moving air, and are often used for storage. The hot air rising from the lower floors of a building is often retained in attics, further compounding their reputation as inhospitable environments. However, in recent years, they have been insulated to help decrease heating costs, since, on average, uninsulated attics account for 15% of the energy loss in average houses.
A loft or mezzanine is also the uppermost space in a building, but is distinguished from an attic in that an attic typically constitutes an entire floor of the building, while a loft or mezzanine covers only a few rooms, leaving one or more sides open to the lower floor.
Attics are found in many different shapes and sizes. They also have many uses: In residential buildings, they are either small unusable spaces filled with insulation, or spaces with storage or HVAC equipment. Some commercial buildings also have attics under pitched roofs that are usually used for storage, mechanical equipment, or for roof access.
Etymology
The word "attic" is derived from the Attica region of Greece and comes from Attic style architecture. The term referred to "a low decorative façade above the main story of a building" and, as used in the phrase "attic order", had originally indicated a small decorative column above a building's main façade.
Ventilation
Modern building codes permit both vented and unvented attics in all climates, if a building is otherwise correctly constructed. However, unoccupied attics should usually be ventilated to reduce the accumulation of heat and moisture that contribute to mold growth and decay of wood rafters and ceiling joists. In cold climates ventilation also helps to prevent ice-dams on the roof and leaks that they cause. In hot climates, ventilation reduces cooling loads.
Sometimes an insulated roof with an internal vapor barrier is preferable to a ventilated attic. In areas with wildfire hazards, sparks can enter attic vents, so houses are safer without vents. Areas with wind-driven rain, fog or sea-spray might also prefer houses with insulated roofs instead of vents. A habitable attic, or a habitable room without an attic may use an insulated roof so that moist air from the habitable area cannot condense on the roofing materials. Also, a building with a complex roof or many piercings between the conditioned area and the attic might control condensation better or more cheaply with an insulated roof and a vapor barrier.
One common code requirement is that the total area of attic vents be equal to or greater than 1/150 of the floor area of the attic, with 50 percent or more of the vent area located in the upper portion of the attic. Vents and louvers should face away from prevailing winds to keep out driven rain. Soffit vents under the eaves normally provide the low vents. Louvered vents in gables can provide the high vents in small houses or short gables.
If a ridge is open, some metal roofing systems can install ridge vents along the entire ridge line of the roof. Various types of turbine ventilators and exhaust fans can assist with attic ventilation and decrease the required area of passive ventilators.
See also
Attic ladder
Basement
Cockloft
Garret
Hayloft
Loft
Penthouse apartment
References
External links
Rooms | Attic | [
"Engineering"
] | 807 | [
"Rooms",
"Architecture"
] |
3,023,216 | https://en.wikipedia.org/wiki/Glossy%20display | A glossy display is an electronic display with a glossy surface. In certain light environments, glossy displays provide better color intensity and contrast ratios than matte displays. The primary disadvantage of these displays is their tendency to reflect any external light, often resulting in an undesirable glare.
Technology
Some LCDs use an antireflective coating, or nanotextured glass surface, to reduce the amount of external light reflecting from the surface without affecting light emanating from the screen as an alternative to matte display.
Disadvantages
Because of the reflective nature of the display, in most lighting conditions that include direct light sources facing the screen, glossy displays create reflections, which can be distracting to the user of the computer. This can be especially distracting to users working in an environment where the position of lights and windows are fixed, such as in an office, as these create unavoidable reflections on glossy displays.
Adverse health effects
Ergonomic studies show that prolonged work in the office environment with the presence of discomforting glares and disturbances from light reflections on the screen can cause mild to severe health effects, ranging from eye strain and headaches to photosensitive epileptic episodes. These effects are usually explained by the physiology of the human eye and the human visual system. The image of light sources reflected in the screen can cause the human visual system to focus on that image, which is usually at a much farther distance than the information shown on the screen. This competition between two images that can be focused is considered to be the primary source of such effects.
Advantages
In controlled environments, such as darkened rooms, or rooms where all light sources are diffused, glossy displays create more saturated colors, deeper blacks, brighter whites, and are sharper than matte displays. This is why supporters of glossy screens consider these types of displays more appropriate for viewing photographs and watching films.
See also
Anti-reflective coating
Optical coating
Matte display
Nanotextured surface
List of glossy display branding manufacturers
References
External links
Glossy versus matte: fight! : From the News Desk at Ars Technica: a report of a Lenovo poll on matte vs. glossy LCDs by Jeremy Reimer, published Oct. 18, 2006.
Display technology | Glossy display | [
"Engineering"
] | 447 | [
"Electronic engineering",
"Display technology"
] |
3,023,644 | https://en.wikipedia.org/wiki/Idose | Idose is a hexose, a six carbon monosaccharide. It has an aldehyde group and is thus an aldose. Idose is not found in nature, but its oxidized derivative iduronic acid, is a component of dermatan sulfate and heparan sulfate, which are glycosaminoglycans. The first and third hydroxyls point the opposite way from the second and fourth. It is made by aldol condensation of D- and L-glyceraldehyde. L-Idose is a C-5 epimer of D-glucose.
It can be identified by mass spectrometry.
References
Aldohexoses
Pyranoses | Idose | [
"Chemistry"
] | 152 | [] |
3,023,772 | https://en.wikipedia.org/wiki/Astrology%20software | Astrology software is a type of computer programs designed to calculate astrological horoscopes. Many of them also assemble interpretive text into narrative reports.
History
Astro Computing Services (ACS) in San Diego, founded by Neil Michelsen in 1973, published a computer-generated astrological ephemeris in 1976, The American Ephemeris.
When personal computers generally became available, astrologers and astrology hobbyists were able to purchase them and use astrological or astronomical calculation software or make such programs themselves. Astrologer and computer programmer Michael Erlewine was involved early in making astrological software for microcomputers available to the general public in the late 1970s. In 1978, Erlewine founded Matrix Software, and in 1980 he published a book with all the algorithms and data required for owners of microcomputers to make their own complete astrological programs.
At first, astrology software was opposed by American astrologers who did not approve of computers in their field. However, acceptance grew as it became clear how more efficient and profitable such software could be.
A few hundred fixed-purpose astrology computers were made. One of which, the Digicomp DR-70 Astrology Minicomputer, was used by Nancy Reagan's astrologer Joan Quigley beginning in about 1981.
Astrology software has been made available in the open-source model, starting with the release of Astrolog in 1991.
Features
Computer astrology programs today typically make accurate planet position calculations, display and print these positions using astrological glyph symbols in graphic charts, save and retrieve individuals' data to and from database files, compare the planet positions of different charts to find the astrological aspects between them (e.g. for compatibility), calculate the dates of important events in the future for a chart, and research the saved chart database. Some generate colorful geographical maps with lines showing where the planets rise and culminate at a significant time, usually the time of birth or the time of inception of an organization (called astrocartography). Astrology programs usually come bundled with an electronic atlas, allowing the review of the longitudes, latitudes, and time zone observance histories for cities and towns. Many assemble interpretive text about the various element combinations in a chart into comprehensive printed reports.
Software development tools for astrology
Software libraries exist to aid in the development of astronomical software. These libraries can also be leveraged for use in astrological projects. One such tool is Swiss Ephemeris, which is an astronomical almanac developed by Astrodienst AG, Switzerland, the makers of Astrolog. It is widely used for calculating the positions of planets, moons, asteroids, and stars for a given date and time. The library can be integrated with several programming languages including C#, C++, Java, and .NET. The Swiss Ephemeris primarily uses the Jet Propulsion Laboratory Development Ephemeris as its source data for positions of the Sun, Moon and planets. It uses data from Astronomisches Rechen-Institut (ARI) in Heidelberg, Germany for the positions of asteroids.
See also
Astrolog
Planetarium software
References
Software
Divination software and games | Astrology software | [
"Astronomy"
] | 654 | [
"Astrology",
"History of astronomy"
] |
3,023,823 | https://en.wikipedia.org/wiki/Star%20count | Star counts are census counts of stars and the statistical and geometrical methods used to correct the corresponding data for bias. The surveys are most often made of nearby stars in the Milky Way galaxy.
The total number of stars counted in a particular direction depends on the location and density of stars, the luminosity function, and the absorption. Star count programs can therefore collect data that bounds or determines these values.
One of the interests of astronomy is to determine how many stars there are of each of several types that stars can be categorized into, and how these stars are distributed in space.
Reasons for star counts
When performing star counts, astronomers consider many different categories that have been created to classify a few stars that have been well studied. One of the hopes of studying the results of star counts is to discover new categories. Different counts typically seek to categorize stars for only a few of the qualities listed below, and determine how common each considered quality is and how stars of that kind are distributed.
Temperature: In astronomy, temperature is usually shown using the letter codes O B A F G K M running from 'blue' (type O, actually bluish white) through white (type F) to 'red' (type M, actually ruddy orange). Types L and T are used for brown dwarfs, whose 'colors' are in the infrared.
Size: Size is usually designated by Roman numerals I (supergiants) through V (dwarfs).
Age: Stars are usually grouped into Population I (young) and Population II (old).
Location: In the Milky Way galaxy the groups are described as thin disk, thick disk, central bulge, and halo.
Multiplicity: Most stars are members of double star, or triple star, or even double-double star systems. Our own sun appears to be unusual for not having a companion star.
There are many finer subdivisions in all of the above categories.
Bias
There are many unavoidable problems in counting stars for the purpose of getting an accurate picture of the distribution of stars in space. The effects of our point of view in the galaxy, the obscuring clouds of gas and dust in the galaxy, and especially the extreme range of inherent brightness, create a biased view of stars.
Stars vary far more in intrinsic brightness than they do in distance.
Our line of sight through the Milky Way is interrupted by great clouds of gas and dust, which block our view of stars more than a few thousand light-years away.
The Sun is located in the disk of the Milky Way, in the northern edge of the thin disk and on the inner edge of a spiral arm called the Orion–Cygnus Arm. There is good reason to believe that stars in the galaxy's thin disk are different from thicker part of the disk, and from the bulge and the halo. Some stars are obviously more common in spiral arms than in the disk in between the arms.
Knowing that these effects create bias, astronomers analyzing star counts attempt to find how much bias each effect has caused and then compensate for it as well as they can.
Inherent luminosity complications
The greatest problem biasing star counts is the extreme differences in inherent brightness of different sizes.
Heavy, bright stars (both giants and blue dwarfs) are the most common stars listed in general star catalogs, even though on average they are rare in space. Small dim stars (red dwarfs) seem to be the most common stars in space, at least locally, but can only be seen with large telescopes, and then only when they are within a few tens of light-years from Earth.
For example, the blue supergiant ζ Puppis is 400 million times more luminous than the nearest star, a red dwarf named Proxima, or α Centauri C. Even though Proxima is only 4.2 light-years away from us, it is so dim that it cannot be seen with the naked eye (one of its companions, α Centauri A, is visible). ζ Puppis is one of the brightest of the visible blue supergiants. It is so bright that it appears to be a second magnitude star, even though ζ Puppis is 1,399 light-years away.
References
Count | Star count | [
"Astronomy"
] | 856 | [
"Astronomical sub-disciplines",
"Stellar astronomy"
] |
3,023,865 | https://en.wikipedia.org/wiki/Glycan | The terms glycans and polysaccharides are defined by IUPAC as synonyms meaning "compounds consisting of a large number of monosaccharides linked glycosidically". However, in practice the term glycan may also be used to refer to the carbohydrate portion of a glycoconjugate, such as a glycoprotein, glycolipid, or a proteoglycan, even if the carbohydrate is only an oligosaccharide. Glycans usually consist solely of O-glycosidic linkages of monosaccharides. For example, cellulose is a glycan (or, to be more specific, a glucan) composed of β-1,4-linked D-glucose, and chitin is a glycan composed of β-1,4-linked N-acetyl-D-glucosamine. Glycans can be homo- or heteropolymers of monosaccharide residues, and can be linear or branched.
Glycans and proteins
Glycans can be found attached to proteins as in glycoproteins and proteoglycans. In general, they are found on the exterior surface of cells. O- and N-linked glycans are very common in eukaryotes but may also be found, although less commonly, in prokaryotes.
N-Linked glycans
Introduction
N-Linked glycans are attached in the endoplasmic reticulum to the nitrogen (N) in the side chain of asparagine (Asn) in the sequon. The sequon is an Asn-X-Ser or Asn-X-Thr sequence, where X is any amino acid except proline and the glycan may be composed of N-acetylgalactosamine, galactose, neuraminic acid, N-acetylglucosamine, fucose, mannose, and other monosaccharides.
Assembly
In eukaryotes, N-linked glycans are derived from a core 14-sugar unit assembled in the cytoplasm and endoplasmic reticulum. First, two N-acetylglucosamine residues are attached to dolichol monophosphate, a lipid, on the external side of the endoplasmic reticulum membrane. Five mannose residues are then added to this structure. At this point, the partially finished core glycan is flipped across the endoplasmic reticulum membrane, so that it is now located within the reticular lumen. Assembly then continues within the endoplasmic reticulum, with the addition of four more mannose residues. Finally, three glucose residues are added to this structure. Following full assembly, the glycan is transferred en bloc by the glycosyltransferase oligosaccharyltransferase to a nascent peptide chain, within the reticular lumen. This core structure of N-linked glycans, thus, consists of 14 residues (3 glucose, 9 mannose, and 2 N-acetylglucosamine).
Image: https://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=glyco.figgrp.469
Dark squares are N-acetylglucosamine; light circles are mannose; dark triangles are glucose.
Processing, modification, and diversity
Once transferred to the nascent peptide chain, N-linked glycans, in general, undergo extensive processing reactions, whereby the three glucose residues are removed, as well as several mannose residues, depending on the N-linked glycan in question. The removal of the glucose residues is dependent on proper protein folding. These processing reactions occur in the Golgi apparatus. Modification reactions may involve the addition of a phosphate or acetyl group onto the sugars, or the addition of new sugars, such as neuraminic acid. Processing and modification of N-linked glycans within the Golgi does not follow a linear pathway. As a result, many different variations of N-linked glycan structure are possible, depending on enzyme activity in the Golgi.
Functions and importance
N-linked glycans are extremely important in proper protein folding in eukaryotic cells. Chaperone proteins in the endoplasmic reticulum, such as calnexin and calreticulin, bind to the three glucose residues present on the core N-linked glycan. These chaperone proteins then serve to aid in the folding of the protein that the glycan is attached to. Following proper folding, the three glucose residues are removed, and the glycan moves on to further processing reactions. If the protein fails to fold properly, the three glucose residues are reattached, allowing the protein to re-associate with the chaperones. This cycle may repeat several times until a protein reaches its proper conformation. If a protein repeatedly fails to properly fold, it is excreted from the endoplasmic reticulum and degraded by cytoplasmic proteases.
N-linked glycans also contribute to protein folding by steric effects. For example, cysteine residues in the peptide may be temporarily blocked from forming disulfide bonds with other cysteine residues, due to the size of a nearby glycan. Therefore, the presence of a N-linked glycan allows the cell to control which cysteine residues will form disulfide bonds.
N-linked glycans also play an important role in cell-cell interactions. For example, tumour cells make N-linked glycans that are abnormal. These are recognized by the CD337 receptor on Natural Killer cells as a sign that the cell in question is cancerous.
Within the immune system the N-linked glycans on an immune cell's surface will help dictate that migration pattern of the cell, e.g. immune cells that migrate to the skin have specific glycosylations that favor homing to that site. The glycosylation patterns on the various immunoglobulins including IgE, IgM, IgD, IgE, IgA, and IgG bestow them with unique effector functions by altering their affinities for Fc and other immune receptors. Glycans may also be involved in "self" and "non self" discrimination, which may be relevant to the pathophysiology of various autoimmune diseases; including rheumatoid arthritis and type 1 diabetes.
The targeting of degradative lysosomal enzymes is also accomplished by N-linked glycans. The modification of an N-linked glycan with a mannose-6-phosphate residue serves as a signal that the protein to which this glycan is attached should be moved to the lysosome. This recognition and trafficking of lysosomal enzymes by the presence of mannose-6-phosphate is accomplished by two proteins: CI-MPR (cation-independent mannose-6-phosphate receptor) and CD-MPR (cation-dependent mannose-6-phosphate receptor).
O-Linked glycans
Introduction
In eukaryotes, O-linked glycans are assembled one sugar at a time on a serine or threonine residue of a peptide chain in the Golgi apparatus. Unlike N-linked glycans, there is no known consensus sequence yet. However, the placement of a proline residue at either -1 or +3 relative to the serine or threonine is favourable for O-linked glycosylation.
Assembly
The first monosaccharide attached in the synthesis of O-linked glycans is N-acetyl-galactosamine. After this, several different pathways are possible. A Core 1 structure is generated by the addition of galactose. A Core 2 structure is generated by the addition of N-acetyl-glucosamine to the N-acetyl-galactosamine of the Core 1 structure. Core 3 structures are generated by the addition of a single N-acetyl-glucosamine to the original N-acetyl-galactosamine. Core 4 structures are generated by the addition of a second N-acetyl-glucosamine to the Core 3 structure. Other core structures are possible, though less common.
Images:
https://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=glyco.figgrp.561 : Core 1 and Core 2 generation. White square = N-acetyl-galactosamine; black circle = galactose; Black square = N-acetyl-glucosamine. Note: There is a mistake in this diagram. The bottom square should always be white in each image, not black.
https://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=glyco.figgrp.562 : Core 3 and Core 4 generation.
A common structural theme in O-linked glycans is the addition of polylactosamine units to the various core structures. These are formed by the repetitive addition of galactose and N-acetyl-glucosamine units. Polylactosamine chains on O-linked glycans are often capped by the addition of a sialic acid residue (similar to neuraminic acid). If a fucose residue is also added, to the next to penultimate residue, a Sialyl-Lewis X (SLex) structure is formed.
Functions and importance
Sialyl lewis x is important in ABO blood antigen determination.
SLex is also important to proper immune response. P-selectin release from Weibel-Palade bodies, on blood vessel endothelial cells, can be induced by a number of factors. One such factor is the response of the endothelial cell to certain bacterial molecules, such as peptidoglycan. P-selectin binds to the SLex structure that is present on neutrophils in the bloodstream and helps to mediate the extravasation of these cells into the surrounding tissue during infection.
O-linked glycans, in particular mucin, have been found to be important in developing normal intestinal microflora. Certain strains of intestinal bacteria bind specifically to mucin, allowing them to colonize the intestine.
Examples of O-linked glycoproteins are:
Glycophorin, a protein in erythrocyte cell membranes
Mucin, a protein in saliva involved in formation of dental plaque
Notch, a transmembrane receptor involved in development and cell fate decisions
Thrombospondin
Factor VII
Factor IX
Urinary type plasminogen activator
Glycosaminoglycans
Another type of cellular glycan is the glycosaminoglycans (GAGs). These comprise 2-aminosugars linked in an alternating fashion with uronic acids, and include polymers such as heparin, heparan sulfate, chondroitin, keratan and dermatan. Some glycosaminoglycans, such as heparan sulfate, are found attached to the cell surface, where they are linked through a tetrasacharide linker via a xylosyl residue to a protein (forming a glycoprotein or proteoglycan).
Glycoscience
A 2012 report from the U.S. National Research Council calls for a new focus on glycoscience, a field that explores the structures and functions of glycans and promises great advances in areas as diverse as medicine, energy generation, and materials science. Until now, glycans have received little attention from the research community due to a lack of tools to probe their often complex structures and properties. The report presents a roadmap for transforming glycoscience from a field dominated by specialists to a widely studied and integrated discipline. As of 2019, NHLBI has established a new national career development consortium for excellence in glycoscience, led by program director Karin Hoffmeister.
Tools used for glycan research
The following are examples of the commonly used techniques in glycan analysis:
High-resolution mass spectrometry (MS) and high-performance liquid chromatography (HPLC)
The most commonly applied methods are MS and HPLC, in which the glycan part is cleaved either enzymatically or chemically from the target and subjected to analysis. In case of glycolipids, they can be analyzed directly without separation of the lipid component.
N-glycans from glycoproteins are analyzed routinely by high-performance-liquid-chromatography (reversed phase, normal phase and ion exchange HPLC) after tagging the reducing end of the sugars with a fluorescent compound (reductive labeling).
A large variety of different labels were introduced in the recent years, where 2-aminobenzamide (AB), anthranilic acid (AA), 2-aminopyridin (PA), 2-aminoacridone (AMAC) and 3-(acetylamino)-6-aminoacridine (AA-Ac) are just a few of them. Different labels have to be used for different ESI modes and MS systems used.
O-glycans are usually analysed without any tags, due to the chemical release conditions preventing them to be labeled.
Fractionated glycans from high-performance liquid chromatography (HPLC) instruments can be further analyzed by MALDI-TOF-MS(MS) to get further information about structure and purity. Sometimes glycan pools are analyzed directly by mass spectrometry without prefractionation, although a discrimination between isobaric glycan structures is more challenging or even not always possible. Anyway, direct MALDI-TOF-MS analysis can lead to a fast and straightforward illustration of the glycan pool.
In recent years, high performance liquid chromatography online coupled to mass spectrometry became very popular. By choosing porous graphitic carbon as a stationary phase for liquid chromatography, even non derivatized glycans can be analyzed. Detection is here done by mass spectrometry, but in instead of MALDI-MS, electrospray ionisation (ESI) is more frequently used.
Multiple reaction monitoring (MRM)
Although MRM has been used extensively in metabolomics and proteomics, its high sensitivity and linear response over a wide dynamic range make it especially suited for glycan biomarker research and discovery. MRM is performed on a triple quadrupole (QqQ) instrument, which is set to detect a predetermined precursor ion in the first quadrupole, a fragmented in the collision quadrupole, and a predetermined fragment ion in the third quadrupole. It is a non-scanning technique, wherein each transition is detected individually and the detection of multiple transitions occurs concurrently in duty cycles. This technique is being used to characterize the immune glycome.
Table 1:Advantages and disadvantages of mass spectrometry in glycan analysis
Arrays
Lectin and antibody arrays provide high-throughput screening of many samples containing glycans. This method uses either naturally occurring lectins or artificial monoclonal antibodies, where both are immobilized on a certain chip and incubated with a fluorescent glycoprotein sample.
Glycan arrays, like that offered by the Consortium for Functional Glycomics and Z Biotech LLC, contain carbohydrate compounds that can be screened with lectins or antibodies to define carbohydrate specificity and identify ligands.
Metabolic and covalent labeling of glycans
Metabolic labeling of glycans can be used as a way to detect glycan structures. A well-known strategy involves the use of azide-labeled sugars which can be reacted using the Staudinger ligation. This method has been used for in vitro and in vivo imaging of glycans.
Tools for glycoproteins
X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy for complete structural analysis of complex glycans is a difficult and complex field. However, the structure of the binding site of numerous lectins, enzymes and other carbohydrate-binding proteins have revealed a wide variety of the structural basis for glycome function. The purity of test samples have been obtained through chromatography (affinity chromatography etc.) and analytical electrophoresis (PAGE (polyacrylamide electrophoresis), capillary electrophoresis, affinity electrophoresis, etc.).
See also
Glycoside
Glycoside hydrolase
Glycosylation
Glycosyltransferase
Glycolipids - for Glycans and lipids
Glycophosphatidylinositol for GPI-Anchors
Resources
National Center for Functional Glycomics (NCFG) The focus of the NCFG is the development in the glycosciences, with an emphasis on exploring the molecular mechanisms of glycan recognition by proteins important in human biology and disease. They have a number of resources for glycan analysis as well as training in glycomics and protocols for glycan analysis
GlyTouCan, Glycan structure repository
Glycosciences.DE , German glycan database
Carbohydrate Structure Database, Russian glycan database
UniCarbKB, Australian glycan database
GlycoSuiteDB, glycan database by Swiss Institute of Bioinformatics
GlyGen, NIH funded glycoinformatics resource
The Consortium for Functional Glycomics (CFG) is a non-profit research initiative comprising eight core facilities and 500+ participating investigators that work together to develop resources and services and make them available to the scientific community free of charge. The data generated by these resources are captured in databases accessible through the Functional Glycomics Gateway, a web resource maintained through a partnership between the CFG and Nature Publishing Group.
Transforming Glycoscience: A Roadmap for the Future by the U.S. National Research Council. This site provides information about the U.S. National Research Council's reports and workshops on glycoscience.
References
External links
Oligosaccharides
Glycoproteins
Carbohydrates
Carbohydrate chemistry
Glycomics | Glycan | [
"Chemistry"
] | 3,974 | [
"Biomolecules by chemical classification",
"Carbohydrates",
"Organic compounds",
"Oligosaccharides",
"Glycomics",
"Carbohydrate chemistry",
"nan",
"Chemical synthesis",
"Glycoproteins",
"Glycobiology"
] |
3,024,021 | https://en.wikipedia.org/wiki/Parasympatholytic | A parasympatholytic agent is a substance or activity that reduces the activity of the parasympathetic nervous system.
The term parasympatholytic typically refers to the effect of a drug, although some poisons act to block the parasympathetic nervous system as well. Most drugs with parasympatholytic properties are anticholinergics.
Parasympatholytic agents and sympathomimetic agents have similar effects to each other, although some differences between the two groups can be observed. For example, both cause mydriasis, but parasympatholytics reduce accommodation (cycloplegia), whereas sympathomimetics do not.
Clinical significance
Parasympatholytic drugs are sometimes used to treat slow heart rhythms (bradycardias or bradydysrhythmias) caused by myocardial infarctions or other pathologies, as well as to treat conditions that cause bronchioles in the lung to constrict, such as asthma. By blocking the parasympathetic nervous system, parasympatholytic drugs can increase heart rate in patients with bradycardic heart rhythms, and open up airways and reduce mucus production in patients with asthma.
See also
Parasympathomimetic drug
References
External links
Overview at salisbury.edu
Anticholinergics | Parasympatholytic | [
"Chemistry",
"Biology"
] | 288 | [
"Biochemistry stubs",
"Biotechnology stubs",
"Biochemistry"
] |
3,024,106 | https://en.wikipedia.org/wiki/Apple%20Expo | The Apple Expo was a European annual sales conference and technology exposition held by Apple Inc. The conference featured over 250 exhibitors annually, with Apple being its main exhibitor. This conference was most often viewed as the European counterpart to MacWorld Expo, a similar conference that was held annually in San Francisco.
History
The Apple Expo event was originally invented and held in France around 1984 by the employees of the French Apple distributor Seedrin Sarl, and its manager Jean-Louis Gassée.
All the employees of this small distributor were each time involved in participating for this annual show, where several third-party software and hardware distributors would also have their booth.
Apple Seedrin (which turned to Apple France) continued for decades to organise this event every mid September. Within the small (100 people) Apple France subsidiary, a team was even created (with Adeline Domenjoz) to set up this event.
Due to the growing size of the event, Reed OIP was contracted for show management.
Around the year 2000, the Apple corporation took the ownership of the Apple Expo organisation, and Steve Jobs included this recurring date in his possible events list. With this new corporate management, the French subsidiary employees slowly stopped being be part of the booth demo team.
The last few years showed that the event was slowly turning into an iPod expo, more than a Mac one. Year after year, Apple stopped releasing new products during this event, removing much of its booth investments, and limited the amount of available new products on show.
The last issue was a Reed Expositions-only event, without even an Apple booth.
There were other similar events held in Europe, like MacExpo in London, but with no link with the Apple Expo.
Below there is a time line of all significant product announcements announced at the Apple Expo:
Timeline
Apple Expo 2002
Companies presented, including:
eBeam
Corel
Epson
HP
Wacom
References
External links
Former Apple Expo Official Site
MacWorld Expo Official Site
Apple Expo 2003 - Keynote Photos
Computer-related trade shows
Apple Inc. conferences | Apple Expo | [
"Technology"
] | 412 | [
"Computer industry",
"Computer-related trade shows"
] |
3,024,257 | https://en.wikipedia.org/wiki/Opal%20%28fuel%29 | Opal is a variety of low-aromatic 91 RON petrol developed in 2005 by BP Australia to combat the rising use of gasoline as an inhalant in remote Indigenous Australian communities.
Though more expensive to produce, requiring a $0.33/litre Federal subsidy, a 2006 report found it would likely save at least $27 million per year when the social and health costs of petrol-sniffing were taken into account.
A 2010 senate report showed that the introduction of Opal in 106 communities across remote and regional Australia had led to a 70% drop in petrol sniffing in those communities.
Typical unleaded petrol contains 25% aromatics, such as toluene, ortho-xylene and para-xylene. In contrast, Opal contains only 5% aromatics, which means that it has less of the toluene and other solvents which produce the intoxication (or "high") that inhalant users are seeking. The Australian Government subsidises Opal's provision and restricts traditional unleaded petrol in some remote communities. According to BP, the lower volatile component in Opal means that cars using it are less prone to vapour lock.
Prior to the introduction of Opal, Comgas (a brand of the aviation fuel avgas) was used in many communities to discourage use of fuel as an inhalant. Unlike Opal, however, Comgas contains tetraethyllead (TEL), a poisonous substance that inhibits catalytic converters and is therefore banned for automobile use in most parts of the world especially after the discovery that it increased concentrations of lead particles over the entire earth, including the poles.
See also
Indigenous health in Australia
Indigenous Australians
References
External links
Manufacturer site
Can new non-toxic products eliminate petrol sniffing behaviours in remote Indigenous communities? (PDF) Brett Badger, BA, RMIT University, June 2005 (large bibliography)
Australian brands
Petroleum products
BP
Inhalants
Aboriginal Australian health
Harm reduction | Opal (fuel) | [
"Chemistry"
] | 402 | [
"Petroleum",
"Petroleum products"
] |
3,024,336 | https://en.wikipedia.org/wiki/Cumene | Cumene (isopropylbenzene) is an organic compound that contains a benzene ring with an isopropyl substituent. It is a constituent of crude oil and refined fuels. It is a flammable colorless liquid that has a boiling point of 152 °C. Nearly all the cumene that is produced as a pure compound on an industrial scale is converted to cumene hydroperoxide, which is an intermediate in the synthesis of other industrially important chemicals, primarily phenol and acetone (known as the cumene process).
Production
Commercial production of cumene is by Friedel–Crafts alkylation of benzene with propylene. The original route for manufacturing of cumene was by alkylation of benzene in the liquid phase using sulfuric acid as a catalyst, but because of the complicated neutralization and recycling steps required, together with corrosion problems, this process has been largely replaced. As an alternative, solid phosphoric acid (SPA) supported on alumina has been used as the catalyst.
Since the mid-1990s, commercial production has switched to zeolite-based catalysts. In this process, the efficiency of cumene production is generally 70-75%. The remaining components are primarily polyisopropyl benzenes. In 1976, an improved cumene process that uses aluminum chloride as a catalyst was developed. The overall conversion of cumene for this process can be as high as 90%.
The addition of two equivalents of propylene gives diisopropylbenzene (DIPB). Using transalkylation, DIPB is comproportionated with benzene to give cumene.
Autoxidation
Depending on the conditions, autoxidation of cumene gives dicumyl peroxide or cumene hydroperoxide. Both reactions exploit the weakness of the tertiary C-H bond. The tendency of cumene to form peroxides by autoxidation poses safety concerns. Tests for peroxides are routinely conducted before heating or distilling.
Applications
Cumene is frequently found as an ingredient in thread locking fluids. Cumene is also a precursor chemical to the herbicide isoproturon.
See also
Pseudocumene
References
External links
National Pollutant Inventory - Cumene fact sheet
Cumene Production from Benzene and Propylene Using Aluminum Chloride Catalyst
Hazardous air pollutants
Alkylbenzenes
C3-Benzenes
Commodity chemicals
Suspected carcinogens
IARC Group 2B carcinogens
Isopropyl compounds | Cumene | [
"Chemistry"
] | 518 | [
"Commodity chemicals",
"Products of chemical industry"
] |
3,024,352 | https://en.wikipedia.org/wiki/Brewer%20and%20Nash%20model | The Brewer and Nash model was constructed to provide information security access controls that can change dynamically. This security model, also known as the Chinese wall model, was designed to provide controls that mitigate conflict of interest in commercial organizations and is built upon an information flow model.
In the Brewer and Nash model, no information can flow between the subjects and objects in a way that would create a conflict of interest.
This model is commonly used by consulting and accounting firms. For example, once a consultant accesses data belonging to Acme Ltd, a consulting client, they may no longer access data to any of Acme's competitors. In this model, the same consulting firm can have clients that are competing with Acme Ltd while advising Acme Ltd. This model uses the principle of data isolation within each conflict class of data to keep users out of potential conflict of interest situations. Because company relationships change all the time, dynamic and up-to-date updates to members and definitions for conflict classes are important.
See also
Bell–LaPadula model
Biba model
Clark–Wilson model
Graham–Denning model
References
Harris, Shon, All-in-one CISSP Exam Guide, Third Edition, McGraw Hill Osborne, Emeryville, California, 2005.
Chapple, Mike, et al, Certified Information System Security Professional - Official Study Guide, Eighth Edition, Sybex, John Wiley & Sons, Indiana, 2018.
External links
Computer security models | Brewer and Nash model | [
"Engineering"
] | 293 | [
"Cybersecurity engineering",
"Computer security models"
] |
3,024,416 | https://en.wikipedia.org/wiki/Graham%E2%80%93Denning%20model | The Graham–Denning model is a computer security model that shows how subjects and objects should be securely created and deleted.
It also addresses how to assign specific access rights. It is mainly used in access control mechanisms for distributed systems. There are three main parts to the model: A set of subjects, a set of objects, and a set of eight rules. A subject may be a process or a user that makes a request to access a resource. An object is the resource that a user or process wants to access.
Features
This model addresses the security issues associated with how to define a set of basic rights on how specific subjects can execute security functions on an object.
The model has eight basic protection rules (actions) that outline:
How to securely create an object.
How to securely create a subject.
How to securely delete an object.
How to securely delete a subject.
How to securely provide the read access right.
How to securely provide the grant access right.
How to securely provide the delete access right.
How to securely provide the transfer access right.
Moreover, each object has an owner that has special rights on it, and each subject has another subject (controller) that has special rights on it.
The model is based on the Access Control Matrix model where rows correspond to subjects and columns correspond to objects and subjects, each element contains a set of rights between subject i and object j or between subject i and subject k.
For example an action A[s,o] contains the rights that subject s has on object o (example: {own, execute}).
When executing one of the 8 rules, for example creating an object, the matrix is changed: a new column is added for that object, and the subject that created it becomes its owner.
Each rule is associated with a precondition, for example if subject x wants to delete object o, it must be its owner (A[x,o] contains the 'owner' right).
Limitations
Harrison-Ruzzo-Ullman extended this model by defining a system of protection based on commands made of primitive operations and conditions.
See also
Access Control Matrix
Bell–LaPadula model
Biba model
Brewer and Nash model
Clark-Wilson model
Harrison–Ruzzo–Ullman model
References
Krutz, Ronald L. and Vines, Russell Dean, The CISSP Prep Guide; Gold Edition, Wiley Publishing, Inc., Indianapolis, Indiana, 2003.
Security in Computing (by Charles P. Pfleeger, Shari Lawrence Pfleeger)
http://www.cs.ucr.edu/~brett/cs165_s01/LECTURE11/lecture11-4up.pdf
Computer security models | Graham–Denning model | [
"Engineering"
] | 547 | [
"Cybersecurity engineering",
"Computer security models"
] |
3,024,546 | https://en.wikipedia.org/wiki/Security%20modes | Generally, security modes refer to information systems security modes of operations used in mandatory access control (MAC) systems. Often, these systems contain information at various levels of security classification. The mode of operation is determined by:
The type of users who will be directly or indirectly accessing the system.
The type of data, including classification levels, compartments, and categories, that are processed on the system.
The type of levels of users, their need to know, and formal access approvals that the users will have.
Dedicated security mode
In this mode of operation, all users must have:
Signed NDA for ALL information on the system.
Proper clearance for ALL information on the system.
Formal access approval for ALL information on the system.
A valid need to know for ALL information on the system.
All users can access ALL data.
System high security mode
In system high mode of operation, all users must have:
Signed NDA for ALL information on the system.
Proper clearance for ALL information on the system.
Formal access approval for ALL information on the system.
A valid need to know for SOME information on the system.
All users can access SOME data, based on their need to know.
Compartmented security mode
In this mode of operation, all users must have:
Signed NDA for ALL information on the system.
Proper clearance for ALL information on the system.
Formal access approval for SOME information they will access on the system.
A valid need to know for SOME information on the system.
All users can access SOME data, based on their need to know and formal access approval.
Multilevel security mode
In multilevel security mode of operation (also called Controlled Security Mode), all users must have:
Signed NDA for ALL information on the system.
Proper clearance for SOME information on the system.
Formal access approval for SOME information on the system.
A valid need to know for SOME information on the system.
All users can access SOME data, based on their need to know, clearance and formal access approval
Summary
See also
Access control
Multifactor authentication
Bell–LaPadula model
Biba model
Clark-Wilson model
Discretionary access control (DAC)
Graham-Denning model
Multilevel security (MLS)
Mandatory access control (MAC)
Security
Security engineering
Take-grant model
References
Krutz, Ronald L. and Vines, Russell Dean, The CISSP Prep Guide; Gold Edition, Wiley Publishing, Inc., Indianapolis, Indiana, 2003.
External links
DoD 5200.28 defines the security terms
Computer security models | Security modes | [
"Engineering"
] | 504 | [
"Cybersecurity engineering",
"Computer security models"
] |
3,024,615 | https://en.wikipedia.org/wiki/Finite%20potential%20well | The finite potential well (also known as the finite square well) is a concept from quantum mechanics. It is an extension of the infinite potential well, in which a particle is confined to a "box", but one which has finite potential "walls". Unlike the infinite potential well, there is a probability associated with the particle being found outside the box. The quantum mechanical interpretation is unlike the classical interpretation, where if the total energy of the particle is less than the potential energy barrier of the walls it cannot be found outside the box. In the quantum interpretation, there is a non-zero probability of the particle being outside the box even when the energy of the particle is less than the potential energy barrier of the walls (cf quantum tunnelling).
Particle in a one-dimensional potential well
For the one-dimensional case on the x-axis, the time-independent Schrödinger equation can be written as:
where
is the reduced Planck constant,
is the mass of the particle,
is the potential energy at each point x,
is the (complex valued) wavefunction, or "eigenfunction", and
is the energy, a real number, sometimes called eigenenergy.
For the case of the particle in a one-dimensional box of length L, the potential is outside the box, and zero for x between and . The wavefunction is composed of different wavefunctions; depending on whether x is inside or outside of the box, such that:
Inside the box
For the region inside the box, V(x) = 0 and Equation 1 reduces to
resembling the time-independent free schrödinger equation, hence
Letting
the equation becomes
with a general solution of
where A and B can be any complex numbers, and k can be any real number.
Outside the box
For the region outside of the box, since the potential is constant, and equation becomes:
There are two possible families of solutions, depending on whether E is less than (the particle is in a bound state) or E is greater than (the particle is in an unbounded state).
If we solve the time-independent Schrödinger equation for an energy , letting such that
then the solution has the same form as the inside-well case:
and, hence, will be oscillatory both inside and outside the well. Thus, the solution is never square integrable; that is, it is always a non-normalizable state. This does not mean, however, that it is impossible for a quantum particle to have energy greater than , it merely means that the system has continuous spectrum above , i.e., the non-normalizable states still contribute to the continuous part of the spectrum as generalized eigenfunctions of an unbounded operator.
This analysis will focus on the bound state, where . Letting
produces
where the general solution is exponential:
Similarly, for the other region outside the box:
Now in order to find the specific solution for the problem at hand, we must specify the appropriate boundary conditions and find the values for A, B, F, G, H and I that satisfy those conditions.
Finding wavefunctions for the bound state
Solutions to the Schrödinger equation must be continuous, and continuously differentiable. These requirements are boundary conditions on the differential equations previously derived, that is, the matching conditions between the solutions inside and outside the well.
In this case, the finite potential well is symmetrical, so symmetry can be exploited to reduce the necessary calculations.
Summarizing the previous sections:
where we found , , and to be:
We see that as goes to , the term goes to infinity. Likewise, as goes to , the term goes to infinity. In order for the wave function to be square integrable, we must set , and we have:
and
Next, we know that the overall function must be continuous and differentiable. In other words, the values of the functions and their derivatives must match up at the dividing points:
These equations have two sorts of solutions, symmetric, for which and , and antisymmetric, for which and . For the symmetric case we get
so taking the ratio gives
Similarly for the antisymmetric case we get
Recall that both and depend on the energy. What we have found is that the continuity conditions cannot be satisfied for an arbitrary value of the energy; because that is a result of the infinite potential well case. Thus, only certain energy values, which are solutions to one or either of these two equations, are allowed. Hence we find that the energy levels of the system below are discrete; the corresponding eigenfunctions are bound states. (By contrast, for the energy levels above are continuous.)
The energy equations cannot be solved analytically. Nevertheless, we will see that in the symmetric case, there always exists at least one bound state, even if the well is very shallow.
Graphical or numerical solutions to the energy equations are aided by rewriting them a little and it should be mentioned that a nice approximation method has been found by Lima which works for any pair of parameters and . If we introduce the dimensionless variables and , and note from the definitions of and that , where , the master equations read
In the plot to the right, for , solutions exist where the blue semicircle intersects the purple or grey curves ( and ). Each purple or grey curve represents a possible solution, within the range . The total number of solutions, , (i.e., the number of purple/grey curves that are intersected by the blue circle) is therefore determined by dividing the radius of the blue circle, , by the range of each solution and using the floor or ceiling functions:
In this case there are exactly three solutions, since .
and , with the corresponding energies
If we want, we can go back and find the values of the constants in the equations now (we also need to impose the normalisation condition). On the right we show the energy levels and wave functions in this case (where ).
We note that however small is (however shallow or narrow the well), there is always at least one bound state.
Two special cases are worth noting. As the height of the potential becomes large, , the radius of the semicircle gets larger and the roots get closer and closer to the values , and we recover the case of the infinite square well.
The other case is that of a very narrow, deep well - specifically the case and with fixed. As it will tend to zero, and so there will only be one bound state. The approximate solution is then , and the energy tends to . But this is just the energy of the bound state of a Delta function potential of strength , as it should be.
A simpler graphical solution for the energy levels can be obtained by normalizing the potential and the energy through multiplication by . The normalized quantities are
giving directly the relation between the allowed couples as
for the even and odd parity wave functions, respectively. In the previous equations only the positive derivative parts of the functions have to be considered. The chart giving directly the allowed couples is reported in the figure.
Asymmetric well
Consider a one-dimensional asymmetric potential well given by the potential
with . The corresponding solution for the wave function with is found to be
and
The energy levels are determined once is solved as a root of the following transcendental equation
where Existence of root to above equation is not always guaranteed, for example, one can always find a value of so small, that for given values of and , there exists no discrete energy level. The results of symmetrical well is obtained from above equation by setting .
Particle in a spherical potential well
Consider the following spherical potential well
where is the radius from the origin. The solution for the wavefunction with zero angular momentum () and with an energy is given by
satisfying the condition
This equation does not always have a solution indicating that in some cases, there are no bound states. The minimum depth of the potential well for which the bound state first appears at is given by
which increases with decreasing well radius . Thus, bound states are not possible if the well is sufficiently shallow and narrow. For well depth slightly exceeding the minimum value, i.e., for , the ground state energy (since we are considering case) is given by
Spherically symmetric annular well
The results above can be used to show that, as to the one-dimensional case, there is two bound states in a spherical cavity, as spherical coordinates make equivalent the radius at any direction.
The ground state (n = 1) of a spherically symmetric potential will always have zero orbital angular momentum (ℓ = n−1), and the reduced wave function satisfies the equation
where is the radial part of the wave function. Notice that for (n = 1) angular part is constant (ℓ = 0).
This is identical to the one-dimensional equation, except for the boundary conditions. As before,
The energy levels for
are determined once is solved as a root of the following transcendental equation
where
Existence of root to above equation is always guaranteed. The results are always with spherical symmetry. It fulfils the condition where the wave does not find any potential inside the sphere: .
Different differential equation lay on when ℓ ≠0, so as above titles, here it is:
The solution can be rationalized by some changes of variable and function to rise a Bessel like differential equation, which solution is:
where , and are Bessel, Newman and Hankel spherical functions respectively, and could be rewritten as function of standard Bessel function.
The energy levels for
are determined once is solved as a root of the following transcendental equation
where
Also this two transcendental equations are solutions:
and also,
Existence of roots to above equations are always guaranteed. The results are always with spherical symmetry.
See also
Potential well
Delta function potential
Infinite potential well
Semicircle potential well
Quantum tunnelling
Rectangular potential barrier
References
Further reading
Quantum mechanical potentials
Quantum models
Exactly solvable models | Finite potential well | [
"Physics"
] | 2,028 | [
"Quantum models",
"Quantum mechanical potentials",
"Quantum mechanics"
] |
3,024,813 | https://en.wikipedia.org/wiki/Dihydroxylation | Dihydroxylation is the process by which an alkene is converted into a vicinal diol. Although there are many routes to accomplish this oxidation, the most common and direct processes use a high-oxidation-state transition metal (typically osmium or manganese). The metal is often used as a catalyst, with some other stoichiometric oxidant present. In addition, other transition metals and non-transition metal methods have been developed and used to catalyze the reaction.
Osmium catalyzed reactions
Osmium tetroxide (OsO4) is a popular oxidant used in the dihydroxylation of alkenes because of its reliability and efficiency with producing syn-diols. Since it is expensive and toxic, catalytic amounts of OsO4 are used in conjunction with a stoichiometric oxidizing agent. The Milas hydroxylation, Upjohn dihydroxylation, and Sharpless asymmetric dihydroxylation reactions all use osmium as the catalyst as well as varying secondary oxidizing agents.
The Milas dihydroxylation was introduced in 1930, and uses hydrogen peroxide as the stoichiometric oxidizing agent. Although the method can produce diols, overoxidation to the dicarbonyl compound has led to difficulties isolating the vicinal diol. Therefore, the Milas protocol has been replaced by the Upjohn and Sharpless asymmetric dihydroxylation.
Upjohn dihydroxylation was reported in 1973 and uses OsO4 as the active catalyst in the dihydroxylation procedure. It also employs N-Methylmorpholine N-oxide (NMO) as the stoichiometric oxidant to regenerate the osmium catalyst, allowing for catalytic amounts of osmium to be used. The Upjohn protocol yields high conversions to the vicinal diol and tolerates many substrates. However, the protocol cannot dihydroxylate tetrasubstituted alkenes. The Upjohn conditions can be used for synthesizing anti-diols from allylic alcohols, as demonstrated by Kishi and coworkers.
Sharpless asymmetric
The Sharpless asymmetric dihydroxylation was developed by K. Barry Sharpless to use catalytic amounts of OsO4 along with the stoichiometric oxidant K3[Fe(CN)6]. The reaction is performed in the presence of a chiral auxiliary. The selection of dihydroquinidine (DHQD) or dihydroquinine (DHQ) as a chiral auxiliary dictates the facial selectivity of the olefin, since the absolute configuration of the ligands are opposite. The catalyst, oxidant, and chiral auxiliary can be purchased premixed for selective dihydroxylation. AD-mix-α contains the chiral auxiliary (DHQ)2PHAL, which positions OsO4 on the alpha-face of the olefin; AD-mix-β contains (DHQD)2PHAL and delivers hydroxyl groups to the beta-face. The Sharpless asymmetric dihydroxylation has a large scope for substrate selectivity by changing the chiral auxiliary class.
Applications of Sharpless methods
The synthesis of highly substituted and stereospecific sugars has been achieved by Sharpless-based methods. Kakelokelose is one specific example.
Mechanism
In the dihydroxylation mechanism, a ligand first coordinates to the metal catalyst (depicted as osmium), which dictates the chiral selectivity of the olefin. The alkene then coordinates to the metal through a (3+2) cycloaddition, and the ligand dissociates from the metal catalyst. Hydrolysis of the olefin then yields the vicinal diol, and oxidation of the catalyst by a stoichiometric oxidant regenerates the metal catalyst to repeat the cycle. The concentration of the olefin is crucial to the enantiomeric excess of the diol since higher concentrations of the alkene can associate with the other catalytic site to produce the other enantiomer.
More variants
As mentioned above, the ability to synthesize anti-diols from allylic alcohols can be achieved with the use of NMO as a stoichiometric oxidant. The use of tetramethylenediamine (TMEDA) as a ligand produced syn-diols with a favorable diastereomeric ratio compared to Kishi’s protocol; however, stoichiometric osmium is employed. Syn-selectivity is due to the hydrogen bond donor ability of the allylic alcohol and the acceptor ability of the diamine. This has since been applied to homoallylic systems.
Alternative to Os-based reagents
Ruthenium-based reagents are rapid. Typically, the ruthenium tetroxide is created in situ from ruthenium trichloride, and the oxidant NaIO4. The turnover-limiting step of the reaction is the hydrolysis step; therefore, sulfuric acid is added to increase the rate of this step.
Manganese is also used in dihydroxylation and is often chosen when osmium tetroxide methods yield poor results. Similar to ruthenium, the oxidation potential of manganese is high, leading to over-oxidation of substrates. Potassium permanganate is often used as the oxidant for dihydroxylation; however, due to its poor solubility in organic solvent, a phase-transfer catalyst (such as benzyltriethylammonium chloride, TEBACl) is also added to increase the number of substrates for dihydroxylation. Mild conditions are required to avoid over-oxidation. In particular, a solution that is too warm, acidic, or concentrated will lead to cleavage of the glycol.
Arene dihydroxylations
The dihydroxylation of aromatic compounds gives dihydrocatechols and related derivatives. The conversions are catalyzed by several enzymes, notably Toluene dioxygenases (TDs) and benzene 1,2-dioxygenase.
(1)
cis-1,2-Dihydrocatechol is a versatile synthetic intermediate.
Prévost and Woodward dihydroxylation
Unlike the other methods described that use transition metals as catalyst, the Prévost and Woodward methods use iodine and a silver salt. However, the addition of water into the reaction directs the cis- and trans- addition of the hydroxyl groups. The Prévost reaction typically uses silver benzoate to produce trans-diols; the Woodward modification of the Prévost reaction uses silver acetate to produce cis-diols. In both the Prévost and Woodward reactions, iodine is first added to the alkene producing a cyclic iodinium ion. The anion from the corresponding silver salt is then added by nucleophilic substitution to the iodinium ion.
In the Prévost reaction, the iodinium ion undergoes nucleophilic attack by benzoate anion. The benzoate anion acts as a nucleophile again to displace iodide through a neighboring-group participation mechanism. A second benzoate anion reacts with the intermediate to produce the anti-substituted dibenzoate product, which can then undergo hydrolysis to yield trans-diols.
The Woodward modification of the Prévost reaction yields cis-diols. Acetate anion reacts with the cyclic iodinium ion to yield an oxonium ion intermediate. This can then readily react with water to give the monoacetate, which can then be hydrolyzed to give a cis-diol
To eliminate the need for silver salts, Sudalai and coworkers modified the Prévost-Woodward reaction; the reaction is catalyzed with LiBr, and uses NaIO4 and PhI(OAc)2 as oxidants.
LiBr reacts with NaIO4 and acetic acid to produce lithium acetate, which can then proceed through the reaction as previously mentioned. The protocol produced high dr for the corresponding diol, depending on the oxidant chosen.
Application of both Woodward and Sharpless methods
Dihydroxylation methods have been investigated for the synthesis of steroids. Brassinosteroids, which is a potential insecticide, has a stereochemically-rich array of hydroxy substituents. The hydroxyl groups in the steroid can be using both Woodward conditions to yield a cis-diol to the A ring of the steroid. Then, the alkene chain on the D ring was dihydroxylated to yield the second cis-diol using OsO4 and NMO as the stoichiometric oxidant.
References
Chemical processes
Alkenes
Diols | Dihydroxylation | [
"Chemistry"
] | 1,859 | [
"Chemical processes",
"Organic compounds",
"Alkenes",
"nan",
"Chemical process engineering"
] |
3,024,922 | https://en.wikipedia.org/wiki/Computer%20security%20model | A computer security model is a scheme for specifying and enforcing security policies. A security model may be founded upon a formal model of access rights, a model of computation, a model of distributed computing, or no particular theoretical grounding at all. A computer security model is implemented through a computer security policy.
For a more complete list of available articles on specific security models, see :Category:Computer security models.
Selected topics
Access control list (ACL)
Attribute-based access control (ABAC)
Bell–LaPadula model
Biba model
Brewer and Nash model
Capability-based security
Clark-Wilson model
Context-based access control (CBAC)
Graham-Denning model
Harrison-Ruzzo-Ullman (HRU)
High-water mark (computer security)
Lattice-based access control (LBAC)
Mandatory access control (MAC)
Multi-level security (MLS)
Non-interference (security)
Object-capability model
Protection ring
Relationship-based access control (ReBAC)
Role-based access control (RBAC)
Take-grant protection model
Discretionary access control (DAC)
See also
Security modes
Protection mechanism
References
Krutz, Ronald L. and Vines, Russell Dean, The CISSP Prep Guide; Gold Edition, Wiley Publishing, Inc., Indianapolis, Indiana, 2003.
CISSP Boot Camp Student Guide, Book 1 (v.082807), Vigilar, Inc. | Computer security model | [
"Engineering"
] | 287 | [
"Cybersecurity engineering",
"Computer security models"
] |
3,025,108 | https://en.wikipedia.org/wiki/Seapost%20Service | A Seapost was a mail compartment aboard an ocean-going vessel wherein international exchange mail was distributed. The first American service of this type was the U.S.-German Seapost, which began operating in 1891 on the S.S. Havel North German Lloyd Line. The service rapidly expanded with routes to Great Britain, Central America, South America, and Asia. The Seapost service still employed fifty-five clerks in early 1941. The last route of this type (to South America) was terminated October 19, 1941, due to unsafe wartime conditions on the Atlantic Ocean. The few remaining Seapost clerks transferred to branches of the Railway Mail Service (RMS). Seapost operations for the US Post Office Department were supervised from a New York City, New York, office.
Seapost offices were also operated by the postal authorities of France, Germany, Great Britain, Italy, Japan and New Zealand.
Sources
Wilking, Clarence. (1985) The Railway Mail Service, Railway Mail Service Library, Boyce, Virginia. Available as an MS Word file at http://www.railwaymailservicelibrary.org/articles/THE_RMS.DOC
United States Sea Post Cancellations Part 1 Transatlantic Routes, Edited by Philip Cockrill, Cockrill Series Booklet No 54
Seaposts of the USA by Roger Hosking, Published by the TPO & Seapost Society, September 2008
External links
TPO and Seapost Society for all collectors of Rail and Ship Mail worldwide
Postal systems
Philatelic terminology | Seapost Service | [
"Technology"
] | 308 | [
"Transport systems",
"Postal systems"
] |
3,025,124 | https://en.wikipedia.org/wiki/Operations%20security | Operations security (OPSEC) is a process that identifies critical information to determine whether friendly actions can be observed by enemy intelligence, determines if information obtained by adversaries could be interpreted to be useful to them, and then executes selected measures that eliminate or reduce adversary exploitation of friendly critical information.
The term "operations security" was coined by the United States military during the Vietnam War.
History
Vietnam
In 1966, United States Admiral Ulysses Sharp established a multidisciplinary security team to investigate the failure of certain combat operations during the Vietnam War. This operation was dubbed Operation Purple Dragon, and included personnel from the National Security Agency and the Department of Defense.
When the operation concluded, the Purple Dragon team codified their recommendations. They called the process "Operations Security" in order to distinguish the process from existing processes and ensure continued inter-agency support.
NSDD 298
In 1988, President Ronald Reagan signed National Security Decision Directive (NSDD) 298. This document established the National Operations Security Program and named the Director of the National Security Agency as the executive agent for inter-agency OPSEC support. This document also established the Interagency OPSEC Support Staff (IOSS).
Private-sector application
The private sector has also adopted OPSEC as a defensive measure against competitive intelligence collection efforts.
IT security
NIST SP 800-53 defines OPSEC as the "process by which potential adversaries can be denied information about capabilities and intentions by identifying, controlling, and protecting generally unclassified evidence of the planning and execution of sensitive activities."
See also
For Official Use Only – FOUO
Information security
Intelligence cycle security
Security
Security culture
Sensitive but unclassified – SBU
Controlled Unclassified Information - CUI
Social engineering
References
Further reading
National Security Decision Directive 298
Purple Dragon: The Origin & Development of the United States OPSEC Program, NSA, 1993.
Operations Security (JP 3-13.3) PDF U.S. DoD Operations Security Doctrine.
External links
U.S. Government OPSEC site
Operation Security Professional's Organization
How to Conduct an OPSEC Assessment
Information operations and warfare
Espionage
Cybersecurity engineering | Operations security | [
"Technology",
"Engineering"
] | 427 | [
"Cybersecurity engineering",
"Computer networks engineering",
"Computer engineering"
] |
3,025,251 | https://en.wikipedia.org/wiki/SnapPea | SnapPea is free software designed to help mathematicians, in particular low-dimensional topologists, study hyperbolic 3-manifolds. The primary developer is Jeffrey Weeks, who created the first version as part of his doctoral thesis, supervised by William Thurston. It is not to be confused with the unrelated android malware with the same name.
The latest version is 3.0d3. Marc Culler, Nathan Dunfield and collaborators have extended the SnapPea kernel and written Python extension modules which allow the kernel to be used in a Python program or in the interpreter. They also provide a graphical user interface written in Python which runs under most operating systems (see external links below).
The following people are credited in SnapPea 2.5.3's list of acknowledgments: Colin Adams, Bill Arveson, Pat Callahan, Joe Christy, Dave Gabai, Charlie Gunn, Martin Hildebrand, Craig Hodgson, Diane Hoffoss, A. C. Manoharan, Al Marden, Dick McGehee, Rob Meyerhoff, Lee Mosher, Walter Neumann, Carlo Petronio, Mark Phillips, Alan Reid, and Makoto Sakuma.
The C source code is extensively commented by Jeffrey Weeks and contains useful descriptions of the mathematics involved with references.
The SnapPeaKernel is released under GNU GPL 2+ as is SnapPy.
Algorithms and functions
At the core of SnapPea are two main algorithms. The first attempts to find a minimal ideal triangulation of a given link complement. The second computes the canonical decomposition of a cusped hyperbolic 3-manifold. Almost all the other functions of SnapPea rely in some way on one of these decompositions.
Minimal ideal triangulation
SnapPea inputs data in a variety of formats. Given a link diagram, SnapPea can ideally triangulate the link complement. It then performs a sequence of simplifications to find a locally minimal ideal triangulation.
Once a suitable ideal triangulation is found, SnapPea can try to find a hyperbolic structure. In his Princeton lecture notes, Thurston noted a method for describing the geometric shape of each hyperbolic tetrahedron by a complex number and a set of nonlinear equations of complex variables whose solution would give a complete hyperbolic metric on the 3-manifold. These equations consist of edge equations and cusp (completeness) equations. SnapPea uses an iterative method utilizing Newton's method to search for solutions. If no solution exists, then this is reported to the user.
The local minimality of the triangulation is meant to increase the likelihood that such a solution exists, since heuristically one might expect such a triangulation to be "straightened" without causing degenerations or overlapping of tetrahedra.
From this description of the hyperbolic structure on a link complement, SnapPea can then perform hyperbolic Dehn filling on the cusps to obtain more hyperbolic 3-manifolds. SnapPea does this by taking any given slopes which determine certain Dehn filling equations (also explained in Thurston's notes), and then adjusting the shapes of the ideal tetrahedra to give solutions to these equations and the edge equations. For almost all slopes, this gives an incomplete hyperbolic structure on the link complement, whose completion gives a hyperbolic structure on the Dehn-filled manifold. Its volume is the sum of the volumes of the adjusted tetrahedra.
Canonical decomposition
SnapPea is usually able to compute the canonical decomposition of a cusped hyperbolic 3-manifold from a given ideal triangulation. If not, then it randomly retriangulates and tries again. This has never been known to fail.
The canonical decomposition allows SnapPea to tell two cusped hyperbolic 3-manifolds apart by turning the problem of recognition into a combinatorial question, i.e. checking if the two manifolds have combinatorially equivalent canonical decompositions. SnapPea is also able to check if two closed hyperbolic 3-manifolds are isometric by drilling out short geodesics to create cusped hyperbolic 3-manifolds and then using the canonical decomposition as before.
The recognition algorithm allow SnapPea to tell two hyperbolic knots or links apart. Weeks, et al., were also able to compile different censuses of hyperbolic 3-manifolds by using the algorithm to cull lists of duplicates.
Additionally, from the canonical decomposition, SnapPea is able to:
Compute the Ford domain
Compute the symmetry group
Computable invariants
Censuses
SnapPea has several databases of hyperbolic 3-manifolds available for systematic study.
Cusped census
Closed census
See also
Regina incorporates aspects of SnapPea.
Computational topology
Thurston's 24 questions
References
External links
SnapPea Jeff Weeks' site
SnapPy Culler and Dunfield's extension
Orb Damian Heard's extension, allows :
hyperbolic manifolds with totally geodesic boundary
orbifolds where the orbifold locus contains trivalent vertices
3-manifolds
Computational topology
Numerical software
Free software programmed in C
Free mathematics software | SnapPea | [
"Mathematics"
] | 1,066 | [
"Computational topology",
"Computational mathematics",
"Free mathematics software",
"Topology",
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"Mathematical software"
] |
3,025,266 | https://en.wikipedia.org/wiki/Ternary%20computer | A ternary computer, also called trinary computer, is one that uses ternary logic (i.e., base 3) instead of the more common binary system (i.e., base 2) in its calculations. Ternary computers use trits, instead of binary bits.
Types of states
Ternary computing deals with three discrete states, but the ternary digits themselves can be defined differently:
Ternary quantum computers use qutrits rather than trits. A qutrit is a quantum state that is a complex unit vector in three dimensions, which can be written as in the bra-ket notation. The labels given to the basis vectors () can be replaced with other labels, for example those given above.
History
One early calculating machine, built entirely from wood by Thomas Fowler in 1840, operated in balanced ternary. The first modern, electronic ternary computer, Setun, was built in 1958 in the Soviet Union at the Moscow State University by Nikolay Brusentsov, and it had notable advantages over the binary computers that eventually replaced it, such as lower electricity consumption and lower production cost. In 1970 Brusentsov built an enhanced version of the computer, which he called Setun-70. In the United States, the ternary computing emulator Ternac working on a binary machine was developed in 1973.
The ternary computer QTC-1 was developed in Canada.
Balanced ternary
Ternary computing is commonly implemented in terms of balanced ternary, which uses the three digits −1, 0, and +1. The negative value of any balanced ternary digit can be obtained by replacing every + with a − and vice versa. It is easy to subtract a number by inverting the + and − digits and then using normal addition. Balanced ternary can express negative values as easily as positive ones, without the need for a leading negative sign as with unbalanced numbers. These advantages make some calculations more efficient in ternary than binary. Considering that digit signs are mandatory, and nonzero digits are magnitude 1 only, notation that drops the '1's and use only zero and the + − signs is more concise than if 1's are included.
Unbalanced ternary
Ternary computing can be implemented in terms of unbalanced ternary, which uses the three digits 0, 1, 2. The original 0 and 1 are explained as an ordinary binary computer, but instead uses 2 as leakage current.
The world's first unbalanced ternary semiconductor design on a large wafer was implemented by the research team led by Kim Kyung-rok at Ulsan National Institute of Science and Technology in South Korea, which will help development of low power and high computing microchips in the future. This research theme was selected as one of the future projects funded by Samsung in 2017, published on July 15, 2019.
Potential future applications
With the advent of mass-produced binary components for computers, ternary computers have diminished in significance. However, Donald Knuth argues that they will be brought back into development in the future to take advantage of ternary logic's elegance and efficiency. One possible way this could happen is by combining an optical computer with the ternary logic system. A ternary computer using fiber optics could use dark as 0 and two orthogonal polarizations of light as +1 and −1.
The Josephson junction has been proposed as a balanced ternary memory cell, using circulating superconducting currents, either clockwise, counterclockwise, or off. "The advantages of the proposed memory circuit are capability of high speed computation, low power consumption and very simple construction with fewer elements due to the ternary operation."
Ternary computing shows promise for implementing fast large language models (LLMs) and potentially other AI applications, in lieu of floating point arithmetic.
In popular culture
In Robert A. Heinlein's novel Time Enough for Love, the sapient computers of Secundus, the planet on which part of the framing story is set, including Minerva, use an unbalanced ternary system. Minerva, in reporting a calculation result, says "three hundred forty one thousand six hundred forty... the original ternary readout is unit pair pair comma unit nil nil comma unit pair pair comma unit nil nil point nil".
Modern researches
With the emergence of Carbon nano tube transistors, many researches have shown interest in designing ternary logic gates using them. During 2020–2024 more than 1000 papers about this subject on IEEE Xplore have been published.
See also
Flip-flap-flop Ternary variant of a flip-flop
References
Further reading
External links
The ternary calculating machine of Thomas Fowler
3niti – Collaboration for Open Ternary Computer Development
Development of ternary computers at Moscow State University
Tunguska – Ternary Operating System emulator
Triador: a ternary computer with 600 ternary multiplexers
5500FP - modern ternary CPU
Classes of computers
Russian inventions
Soviet inventions | Ternary computer | [
"Technology"
] | 1,021 | [
"Computers",
"Computer systems",
"Classes of computers"
] |
3,025,357 | https://en.wikipedia.org/wiki/Pierre%20Lecomte%20du%20No%C3%BCy | Pierre Lecomte du Noüy (; 20 December 1883 – 22 September 1947) was a French biophysicist and philosopher. He is probably best remembered by scientists for his work on the surface tension, and other properties, of liquids.
Early life and education
Du Noüy was a descendant of the French dramatist Pierre Corneille. His mother, Hermine Lecomte du Noüy, wrote many novels, one of which, Amitié Amoureuse, was translated into 16 languages and ran for 600 editions in France.
Born and educated in Paris, France, du Noüy obtained the degrees of LL.B., Ph.B., Sc.B., Ph.D., and Sc.D.
Career
He was an associate member of the Rockefeller Institute working in Alexis Carrel's lab from 1920 through 1928, head for 10 years of the biophysics division of the Pasteur Institute, and the author of some 200 published papers.
He invented a tensiometer, a scientific apparatus that used his du Noüy ring method to measure the surface tension of liquids.
Du Noüy believed that mankind should have confidence in science, but be aware that we know less about the material world than is commonly believed.
Telefinalism
Du Noüy converted from agnosticism to Christianity. He supported a theistic and teleological interpretation of evolution. In his book Human Destiny he wrote that biological evolution continues to a spiritual and moral plane. Du Noüy met Pierre Teilhard de Chardin who shared similar interests in evolution and spirituality.
Du Noüy developed his own hypothesis of orthogenesis known as "telefinalism". According to Du Noüy evolution could not occur by chance alone and that on an average since "the beginning of the world it has followed an ascending path, always oriented in the same direction." He accepted naturalistic evolutionary mechanisms such as mutation and natural selection but believed science could not explain all evolutionary phenomena or the origin of life. According to his telefinalist hypothesis a transcendent cause which he equated with God is directing the evolutionary process.
His "telefinalist" hypothesis was criticized by Carl Hempel, Leo Koch and George Gaylord Simpson as nonscientific.<ref>Koch, Leo (1957). "Vitalistic-Mechanistic Controversy", The Scientific Monthly',' Vol. 85, No. 5, pp. 245–255.</ref>
PublicationsBetween Knowing and Believing (1967)The Road to Reason (1948)Human Destiny (1947)
Biological Time (1937)An Interfacial Tensiometer for Universal Use (1925). The Journal of General Physiology. Volume 7, issue 5, pp. 625–633
Quotes
See also
Du Noüy ring method
References
Further reading
George Nauman Shuster, Ralph E. Thorson (1970). Evolution in Perspective: Commentaries in Honor of Pierre Lecomte du Noüy''. University of Notre Dame Press.
External links
Papers of Pierre Lecomte du Noüy (Pasteur Institute)
Papers of Pierre Lecomte du Noüy at The University of Arizona
1883 births
1947 deaths
20th-century French male writers
20th-century French philosophers
French male non-fiction writers
Orthogenesis
Theistic evolutionists
Academic staff of the University of Paris | Pierre Lecomte du Noüy | [
"Biology"
] | 677 | [
"Orthogenesis",
"Obsolete biology theories",
"Biology theories",
"Non-Darwinian evolution",
"Theistic evolutionists"
] |
3,025,578 | https://en.wikipedia.org/wiki/Web%20content%20development | Web content development is the process of researching, writing, gathering, organizing, and editing information for publication on websites. Website content may consist of prose, graphics, pictures, recordings, movies, or other digital assets that could be distributed by a hypertext transfer protocol server, and viewed by a web browser.
Web developers and content developers
When the World Wide Web began, web developers either developed online content themselves, or modified existing documents and coded them into hypertext markup language (HTML). In time, the field of website development came to encompass many technologies, so it became difficult for website developers to maintain so many different skills.
Content developers are specialized website developers who have content generation skills such as graphic design, multimedia development, professional writing, and documentation. They can integrate content into new or existing websites without using information technology skills such as script language programming and database programming.
Content developers or technical content developers can also be technical writers who produce technical documentation that helps people understand and use a product or service. This documentation includes online help, manuals, white papers, design specifications, developer guides, deployment guides, release notes, etc.
Search engine optimization
Content developers may also be search engine optimization specialists, or internet marketing professionals. High quality, unique content is what search engines are looking for. Content development specialists, therefore, have a very important role to play in the search engine optimization process. One issue currently plaguing the world of web content development is keyword-stuffed content which are prepared solely for the purpose of manipulating search engine rankings. The effect is that content is written to appeal to search engine (algorithms) rather than human readers. Search engine optimization specialists commonly submit content to article directories to build their website's authority on any given topic. Most article directories allow visitors to republish submitted content with the agreement that all links are maintained. This has become a method of search engine optimization for many websites today. If written according to SEO copywriting rules, the submitted content will bring benefits to the publisher (free SEO-friendly content for a webpage) as well as to the author (a hyperlink pointing to his/her website, placed on an SEO-friendly webpage).
New content types
Web content is no longer restricted to text. Search engines now index audio/visual media, including video, images, PDFs, and other elements of a web page. Website owners sometimes use content protection networks to scan for plagiarized content.
See also
Web content
Web content lifecycle
Content marketing
Search engine optimization
Content designer
Content management
Content adaptation
Professional writing
Technical writer
Web content management system
References
Web development
Web content | Web content development | [
"Engineering"
] | 529 | [
"Software engineering",
"Web development"
] |
3,025,604 | https://en.wikipedia.org/wiki/Exoelectron%20emission | In atomic physics, exoelectron emission (EE) is a weak electron emission, appearing only from pretreated (irradiated, deformed etc.) objects. The pretreatment ("excitation") turns the objects into an unequilibrial state. EE accompanies the relaxation of these unequilibria. The relaxation can be stimulated e.g. by slight heating or longwave illumination, not causing emission from untreated samples. Accordingly, thermo- and photostimulated EE (TSEE, PSEE) are distinguished. Thus, EE is an electron emission analogue of such optical phenomena as phosphorescence, thermo- and photostimulated luminescence.
References
Atomic, molecular, and optical physics | Exoelectron emission | [
"Physics",
"Chemistry"
] | 164 | [
"Nuclear and atomic physics stubs",
" molecular",
"Nuclear physics",
"Atomic",
" and optical physics"
] |
3,025,610 | https://en.wikipedia.org/wiki/Drove%20chisel | A drove chisel is a tool used by stonemasons for smoothing off roughly finished stones. When first cut from the quarry, stones are frequently have large grooves, droves, left from the splitting process. The droving chisel is used for the next stage, making the surface of the stone flat enough to use. The drove chisel is used for softer rocks such as limestone and marble, while harder rock such as granite requires a point-toothed chisel.
Notes
Masonry
Chisels | Drove chisel | [
"Engineering"
] | 103 | [
"Construction",
"Masonry"
] |
3,025,636 | https://en.wikipedia.org/wiki/Organic%20search%20results | In web search engines, organic search results are the query results which are calculated strictly algorithmically, and not affected by advertiser payments. They are distinguished from various kinds of sponsored results, whether they are explicit pay per click advertisements, shopping results, or other results where the search engine is paid either for showing the result, or for clicks on the result.
Background
The Google, Yahoo!, Bing, and Sogou search engines insert advertising on their search results pages. In U.S. law, advertising must be distinguished from organic results. This is done with various differences in background, text, link colors, and/or placement on the page. However, a 2004 survey found that a majority of search engine users could not distinguish the two.
Because so few ordinary users (38% according to Pew Research Center) realized that many of the highest placed "results" on search engine results pages (SERPs) were ads, the search engine optimization industry began to distinguish between ads and natural results. The perspective among general users was that all results were, in fact, "results." So the qualifier "organic" was invented to distinguish non-ad search results from ads. It has been used since at least 2004.
Because the distinction is important (and because the word "organic" has many metaphorical uses) the term is now in widespread use within the search engine optimization and web marketing industry. As of July 2009, the term "organic search" is now commonly used outside the specialist web marketing industry, even used frequently by Google (throughout the Google Analytics site, for instance).
Google claims their users click (organic) search results more often than ads, essentially rebutting the research cited above. A 2012 Google study found that 81% of ad impressions and 66% of ad clicks happen when there is no associated organic search result on the first page. Research has shown that searchers may have a bias against ads, unless the ads are relevant to the searcher's need or intent.
The same report and others going back to 1997 by Pew show that users avoid clicking "results" they know to be ads.
According to a June 2013 study by Chitika, 9 out of 10 searchers don't go beyond Google's first page of organic search results, a claim often cited by the search engine optimization (SEO) industry to justify optimizing websites for organic search. Organic SEO describes the use of certain strategies or tools to elevate a website's content in the "free" search results.
Users can prevent ads in search results and list only organic results by using browser add-ons and plugins. Other browsers may have different tools developed for blocking ads.
Organic search engine optimization is the process of improving web sites' rank in organic search results.
See also
Internet marketing
References
Search engine optimization
Internet terminology
Online advertising | Organic search results | [
"Technology"
] | 577 | [
"Computing terminology",
"Internet terminology"
] |
3,025,998 | https://en.wikipedia.org/wiki/TRAIL | In the field of cell biology, TNF-related apoptosis-inducing ligand (TRAIL), is a protein functioning as a ligand that induces the process of cell death called apoptosis.
TRAIL is a cytokine that is produced and secreted by most normal tissue cells. It causes apoptosis primarily in tumor cells, by binding to certain death receptors. TRAIL and its receptors have been used as the targets of several anti-cancer therapeutics since the mid-1990s, such as Mapatumumab. However, as of 2013, these have not shown significant survival benefit. TRAIL has also been implicated as a pathogenic or protective factor in various pulmonary diseases, particularly pulmonary arterial hypertension.
TRAIL has also been designated CD253 (cluster of differentiation 253) and TNFSF10 (tumor necrosis factor (ligand) superfamily, member 10).
Gene
In humans, the gene that encodes TRAIL is located at chromosome 3q26, which is not close to other TNF family members. The genomic structure of the TRAIL gene spans approximately 20 kb and is composed of five exonic segments 222, 138, 42, 106, and 1245 nucleotides and four introns of approximately 8.2, 3.2, 2.3 and 2.3 kb.
The TRAIL gene lacks TATA and CAAT boxes and the promoter region contains putative response elements for transcription factors GATA, AP-1, C/EBP, SP-1, OCT-1, AP3, PEA3, CF-1, and ISRE.
The TRAIL gene as a drug target
TIC10 (which causes expression of TRAIL) was investigated in mice with various tumour types.
Small molecule ONC201 causes expression of TRAIL which kills some cancer cells.
Structure
TRAIL shows homology to other members of the tumor necrosis factor superfamily. It is composed of 281 amino acids and has characteristics of a type II transmembrane protein. The N-terminal cytoplasmic domain is not conserved across family members, however, the C-terminal extracellular domain is conserved and can be proteolytically cleaved from the cell surface. TRAIL forms a homotrimer that binds three receptor molecules.
Function
TRAIL binds to the death receptors DR4 (TRAIL-RI) and DR5 (TRAIL-RII). The process of apoptosis is caspase-8-dependent. Caspase-8 activates downstream effector caspases including procaspase-3, -6, and -7, leading to activation of specific kinases. TRAIL also binds the receptors DcR1 and DcR2, which do not contain a cytoplasmic domain (DcR1) or contain a truncated death domain (DcR2). DcR1 functions as a TRAIL-neutralizing decoy-receptor. The cytoplasmic domain of DcR2 is functional and activates NFkappaB.
In cells expressing DcR2, TRAIL binding therefore activates NFkappaB, leading to transcription of genes known to antagonize the death signaling pathway and/or to promote inflammation. Application of engineered ligands that have variable affinity for different death (DR4 and DR5) and decoy receptors (DCR1 and DCR2) may allow selective targeting of cancer cells by controlling activation of Type 1/Type 2 pathways of cell death and single cell fluctuations. Luminescent iridium complex-peptide hybrids, which mimic TRAIL, have recently been synthesized in vitro. These artificial TRAIL mimics bind to DR4/DR5 on cancer cells and induce cell death via both apoptosis and necrosis, which makes them a potential candidate for anticancer drug development.
The TRAIL receptors as a drug target
In clinical trials only a small proportion of cancer patients responded to various drugs that targeted TRAIL death receptors. Many cancer cell lines develop resistance to TRAIL and limits the efficacy of TRAIL-based therapies.
Interactions
TRAIL has been shown to interact with TNFRSF10B.
See also
The Proteolysis Map
References
Further reading
External links
Apoptosis, Trail & Caspase 8 - The Proteolysis Map-animation
Cell biology
Clusters of differentiation
Anticancer genes | TRAIL | [
"Biology"
] | 866 | [
"Cell biology"
] |
3,026,193 | https://en.wikipedia.org/wiki/Alias%20%28command%29 | In computing, alias is a command in various command-line interpreters (shells), which enables a replacement of a word by another string. It is mainly used for abbreviating a system command, or for adding default arguments to a regularly used command. alias is available in Unix shells, AmigaDOS, 4DOS/4NT, FreeDOS, KolibriOS, Windows PowerShell, ReactOS, and the EFI shell. Aliasing functionality in the MS-DOS and Microsoft Windows operating systems is provided by the DOSKey command-line utility.
An alias will last for the life of the shell session. Regularly used aliases can be set from the shell's rc file (such as .bashrc) so that they will be available upon the start of the corresponding shell session. The alias commands may either be written in the config file directly or sourced from a separate file.
History
In Unix, aliases were introduced in the C shell to survive in descendant shells such as tcsh and bash. C shell aliases were strictly limited to one line. This was useful for creating simple shortcut commands, but not more complex constructs. Older versions of the Bourne shell did not offer aliases, but it did provide functions, which are more powerful than the csh alias concept. The alias concept from csh was imported into Bourne Again Shell (bash) and the Korn shell (ksh). With shells that support both functions and aliases but no parameterized inline shell scripts, the use of functions wherever possible is recommended. Cases where aliases are necessary include situations where chained aliases are required (bash and ksh).
The command has also been ported to the IBM i operating system.
Usage
Creating aliases
Common Unix shells
Non-persistent aliases can be created by supplying name/value pairs as arguments for the alias command. In Unix shells the syntax is:
alias gc='git commit'
C shell
The corresponding syntax in the C shell or tcsh shell is:
alias gc "git commit"
This alias means that when the command gc is read in the shell, it will be replaced with git commit and that command will be executed instead.
4DOS
In the 4DOS/4NT shell the following syntax is used to define cp as an alias for the 4DOS copy command:
alias cp copy
Windows PowerShell
To create a new alias in Windows PowerShell, the new-alias cmdlet can be used:
new-alias ci copy-item
This creates a new alias called ci that will be replaced with the copy-item cmdlet when executed.
In PowerShell, an alias cannot be used to specify default arguments for a command. Instead, this must be done by adding items to the collection $PSDefaultParameterValues, one of the PowerShell preference variables.
Viewing currently defined aliases
To view defined aliases the following commands can be used:
alias # Used without arguments; displays a list of all current aliases
alias -p # List aliases in a way that allows re-creation by sourcing the output; not available in 4DOS/4NT and PowerShell
alias myAlias # Displays the command for a defined alias
Overriding aliases
In Unix shells, it is possible to override an alias by quoting any character in the alias name when using the alias. For example, consider the following alias definition:
alias ls='ls -la'
To override this alias and execute the ls command as it was originally defined, the following syntax can be used:
'ls'
or
\ls
In the 4DOS/4NT shell it is possible to override an alias by prefixing it with an asterisk. For example, consider the following alias definition:
alias dir = *dir /2/p
The asterisk in the 2nd instance of dir causes the unaliased dir to be invoked, preventing recursive alias expansion. Also the user can get the unaliased behaviour of dir at the command line by using the same syntax:
*dir
Changing aliases
In Windows PowerShell, the set verb can be used with the alias cmdlet to change an existing alias:
set-alias ci cls
The alias ci will now point to the cls command.
In the 4DOS/4NT shell, the eset command provides an interactive command line to edit an existing alias:
eset /a cp
The /a causes the alias cp to be edited, as opposed to an environment variable of the same name.
Removing aliases
In Unix shells and 4DOS/4NT, aliases can be removed by executing the unalias command:
unalias copy # Removes the copy alias
unalias -a # The -a switch will remove all aliases; not available in 4DOS/4NT
unalias * # 4DOS/4NT equivalent of `unalias -a` - wildcards are supported
In Windows PowerShell, the alias can be removed from the alias:\ drive using remove-item:
remove-item alias:ci # Removes the ci alias
Features
Chaining
An alias usually replaces just the first word. But some shells, such as and , allow a sequence or words to be replaced. This particular feature is unavailable through the function mechanism.
The usual syntax is to define the first alias with a trailing space character. For instance, using the two aliases:
alias list='ls ' # note the trailing space to trigger chaining
alias long='-Flas' # options to ls for a long listing
allows:
list long myfile # becomes "ls -Flas myfile" when run
for a long listing, where "long" is also evaluated as an alias.
Command arguments
In the C Shell, arguments can be embedded inside the command using the string . For example, with this alias:
alias ls-more 'ls \!* | more'
ls-more /etc /usr expands to ls /etc /usr | more to list the contents of the directories /etc and /usr, pausing after every screenful. Without ,
alias ls-more 'ls | more'
would instead expand to ls | more /etc /usr which incorrectly attempts to open the directories in more.
The Bash and Korn shells instead use shell functions — see § Alternatives below.
Alternatives
Aliases should usually be kept simple. Where it would not be simple, the recommendation is usually to use one of the following:
Shell scripts, which essentially provide the full ability to create new system commands.
Symbolic links in the user's PATH (such as /bin). This method is useful for providing an additional way of calling the command, and in some cases may allow access to a buried command function for the small number of commands that use their invocation name to select the mode of operation.
Shell functions, especially if the command being created needs to modify the internal runtime environment of the shell itself (such as environment variables), needs to change the shell's current working directory, or must be implemented in a way which guarantees they it appear in the command search path for anything but an interactive shell (especially any "safer" version of , , and so forth).
The most common form of aliases, which just add a few options to a command and then include the rest of the command line, can be converted easily to shell functions following this pattern:
alias ll='ls -Flas' # long listing, alias
ll () { ls -Flas "$@" ; } # long listing, function
To prevent a function from calling itself recursively, use command:
ls () { command ls --color=auto "$@" ; }
In older Bourne shells use /bin/ls instead of command ls.
References
Further reading
External links
Bash man page for alias
The alias Command by The Linux Information Project (LINFO)
Alias
IBM i Qshell commands
ReactOS commands
Windows commands
Unix SUS2008 utilities
Windows administration | Alias (command) | [
"Technology"
] | 1,649 | [
"IBM i Qshell commands",
"Standard Unix programs",
"Windows commands",
"Computing commands",
"ReactOS commands"
] |
3,026,307 | https://en.wikipedia.org/wiki/Turnover%20number | In chemistry, the term "turnover number" has two distinct meanings.
In enzymology, the turnover number () is defined as the limiting number of chemical conversions of substrate molecules per second that a single active site will execute for a given enzyme concentration for enzymes with two or more active sites. For enzymes with a single active site, is referred to as the catalytic constant. It can be calculated from the limiting reaction rate and catalyst site concentration as follows:
(See Michaelis–Menten kinetics).
In other chemical fields, such as organometallic catalysis, turnover number (TON) has a different meaning: the number of moles of substrate that a mole of catalyst can convert before becoming inactivated:
An ideal catalyst would have an infinite turnover number in this sense, because it would never be consumed. The term turnover frequency (TOF) is used to refer to the turnover per unit time, equivalent to the meaning of turnover number in enzymology.
For most relevant industrial applications, the turnover frequency is in the range of for enzymes). The enzyme catalase has the largest turnover frequency, with values up to 4 s−1 having been reported.
Turnover number of diffusion-limited enzymes
Acetylcholinesterase is a serine hydrolase with a reported catalytic constant greater than 104 s−1. This implies that this enzyme reacts with acetylcholine at close to the diffusion-limited rate.
Carbonic anhydrase is one of the fastest enzymes, and its rate is typically limited by the diffusion rate of its substrates. Typical catalytic constants for the different forms of this enzyme range between 104 s−1 and 106 s−1.
See also
Catalysis
References
Enzyme kinetics
Units of catalytic activity | Turnover number | [
"Chemistry",
"Mathematics"
] | 350 | [
"Catalysis",
"Units of catalytic activity",
"Enzyme kinetics",
"Quantity",
"Chemical kinetics",
"Units of measurement"
] |
3,026,353 | https://en.wikipedia.org/wiki/Adverse%20yaw | Adverse yaw is the natural and undesirable tendency for an aircraft to yaw in the opposite direction of a roll. It is caused by the difference in lift and drag of each wing. The effect can be greatly minimized with ailerons deliberately designed to create drag when deflected upward and/or mechanisms which automatically apply some amount of coordinated rudder. As the major causes of adverse yaw vary with lift, any fixed-ratio mechanism will fail to fully solve the problem across all flight conditions and thus any manually operated aircraft will require some amount of rudder input from the pilot in order to maintain coordinated flight.
History
Adverse yaw was first experienced by the Wright brothers when they were unable to perform controlled turns in their 1901 glider which had no vertical control surface. Orville Wright later described the glider's lack of directional control.
Causes
Adverse yaw is a secondary effect of the inclination of the lift vectors on the wing due to its rolling velocity and of the application of the ailerons. Some pilot training manuals focus mainly on the additional drag caused by the downward-deflected aileron
and make only brief or indirect mentions of roll effects. In fact the rolling of the wings usually causes a greater effect than the ailerons. Assuming a roll rate to the right, as in the diagram, the causes are explained as follows:
Lift vector deflection during rolling
During a positive rolling motion, the left wing moves upward. If an aircraft were somehow suspended in air with no motion other than a positive roll, then from the point of view of the left wing, air will be coming from above and striking the upper surface of the wing. Thus, the left wing will experience a small amount of oncoming airflow merely from the rolling motion. This can be conceptualized as a vector originating from the left wing and pointing towards the oncoming air during the positive roll, i.e. perpendicularly upwards from the left wing's surface. If this positive-rolling aircraft were additionally moving forward in flight, then the vector pointing towards the oncoming air will be mostly forward due to forward-moving flight, but also slightly upward due to the rolling motion. This is the dashed vector coming from the left wing in the diagram.
Thus, for the left wing of a forward-moving aircraft, a positive roll causes the oncoming air to be deflected slightly upwards. Equivalently, the left wing's effective angle of attack is decreased due to the positive roll. By definition, lift is perpendicular to the oncoming flow. The upward deflection of oncoming air causes the lift vector to be deflected backward. Conversely, as the right wing descends, its vector pointing towards the oncoming air is deflected downward and its lift vector is deflected forward. The backward deflection of lift for the left wing and the forward deflection of lift for the right wing results in an adverse yaw moment to the left, opposite to the intended right turn. This adverse yaw moment is present only while the aircraft is rolling relative to the surrounding air, and disappears when the aircraft's bank angle is steady.
Induced drag
Initiating a roll to the right requires a briefly greater lift on the left than the right. This also causes a greater induced drag on the left than the right, which further adds to the adverse yaw, but only briefly. Once a steady roll rate is established the left/right lift imbalance dwindles, while the other mechanisms described above persist.
Profile drag
The downward aileron deflection on the left increases the airfoil camber, which will typically increase the profile drag. Conversely, the upward aileron deflection on the right will decrease the camber and profile drag. The profile drag imbalance adds to the adverse yaw. A Frise aileron reduces this imbalance drag, as described further below.
Minimizing the adverse yaw
There are a number of aircraft design characteristics which can be used to reduce adverse yaw to ease the pilot workload:
Yaw stability
A strong directional stability is the first way to reduce adverse yaw. This is influenced by the vertical tail moment (area and lever arm about gravity center).
Lift coefficient
As the tilting of the left/right lift vectors is the major cause to adverse yaw, an important parameter is the magnitude of these lift vectors, or the aircraft's lift coefficient to be more specific. Flight at low lift coefficient (or high speed compared to minimum speed) produces less adverse yaw.
Aileron to rudder mixing
As intended, the rudder is the most powerful and efficient means of managing yaw but mechanically coupling it to the ailerons is impractical. Electronic coupling is commonplace in fly-by-wire aircraft.
Differential aileron deflection
The geometry of most aileron linkages can be configured so as to bias the travel further upward than downward. By excessively deflecting the upward aileron, profile drag is increased rather than reduced and separation drag further aids in producing drag on the inside wing, producing a yaw force in the direction of the turn. Though not as efficient as rudder mixing, aileron differential is very easy to implement on almost any airplane and offers the significant advantage of reducing the tendency for the wing to stall at the tip first by limiting the downward aileron deflection and its associated effective increase in angle of attack.
Most airplanes use this method of adverse yaw mitigation — particularly noticeable on one of the first well-known aircraft to ever use them, the de Havilland Tiger Moth training biplane of the 1930s — due to the simple implementation and safety benefits.
Frise ailerons
Frise ailerons are designed so that when up aileron is applied, some of the forward edge of the aileron will protrude downward into the airflow, causing increased drag on this (down-going) wing. This will counter the drag produced by the other aileron, thus reducing adverse yaw.
Unfortunately, as well as reducing adverse yaw, Frise ailerons will increase the overall drag of the aircraft much more than applying rudder correction. Therefore, they are less popular in aircraft where minimizing drag is important (e.g. in a glider).
Note: Frise ailerons were primarily designed to reduce roll control forces. Contrary to the illustration, the aileron leading edge is in fact rounded to prevent flow separation and flutter at negative deflections. That prevents important differential drag forces.
Roll spoilers
On large aircraft where rudder use is inappropriate at high speeds or ailerons are too small at low speeds, roll spoilers (also called spoilerons) can be used to minimise adverse yaw or increase roll moment. To function as a lateral control, the spoiler is raised on the down-going wing (up aileron) and remains retracted on the other wing. The raised spoiler increases the drag, and so the yaw is in the same direction as the roll.
References and notes
Collection of balanced-aileron test data, F.M. Rogallo, Naca WR-L 419
Aerodynamics
Gliding technology | Adverse yaw | [
"Chemistry",
"Engineering"
] | 1,464 | [
"Aerospace engineering",
"Aerodynamics",
"Fluid dynamics"
] |
3,026,384 | https://en.wikipedia.org/wiki/Phantom%20withdrawal | A phantom withdrawal is a cash withdrawal from an automatic teller machine where money has been withdrawn from an account, and neither the customer nor the bank admit liability.
If the banks are unable to find any error on their side, they conclude that the withdrawals were done by the customers. Many experts ascribe phantom withdrawals to criminal activity done using the banking network itself.
See also
Automated Teller Machine (ATM)
ATM Industry Association (ATMIA)
Security of ATMs
References
External links
- A website devoted to the topic
Automated teller machines | Phantom withdrawal | [
"Engineering"
] | 108 | [
"Automation",
"Automated teller machines"
] |
3,026,507 | https://en.wikipedia.org/wiki/MOS%20Technology%206532 | The 6532 RAM-I/O-Timer (RIOT) was an integrated circuit made by MOS Technology, as well as second sources such as Rockwell. It incorporates 128 bytes of static RAM, two bidirectional 8-bit digital input/output ports, and a Programmable interval timer. This high degree of integration made it popular in the late 1970s and early 1980s, as it could take the place of several different integrated circuits (ICs).
It is used in the Atari 2600 video game console. The chip was also deployed in Gottlieb pinball machines, such as Haunted House and Black Hole, the Atari 810 and 1050 disk drives, as well as Commodore's 8050, 8250 & 8250LP PET disk drives. The Atari 850 Interface, which gives the Atari 400 and 800 computers an RS-232 interface, uses two 6532 chips.
6532 ICs were available in 1 MHz and 2 MHz versions. The form factor was a JEDEC-standard, 40-pin DIP (ceramic or plastic).
External links
6532 Datasheet (MOS) (GIF format, zipped)
6532 Datasheet (Rockwell) (PDF format)
MOS Technology integrated circuits | MOS Technology 6532 | [
"Technology"
] | 253 | [
"Computing stubs",
"Computer hardware stubs"
] |
3,027,037 | https://en.wikipedia.org/wiki/Bosonization | In theoretical condensed matter physics and quantum field theory, bosonization is a mathematical procedure by which a system of interacting fermions in (1+1) dimensions can be transformed to a system of massless, non-interacting bosons.
The method of bosonization was conceived independently by particle physicists Sidney Coleman and Stanley Mandelstam; and condensed matter physicists Daniel C. Mattis and Alan Luther in 1975.
In particle physics, however, the boson is interacting, cf, the Sine-Gordon model, and notably through topological interactions, cf. Wess–Zumino–Witten model.
The basic physical idea behind bosonization is that particle-hole excitations are bosonic in character. However, it was shown by Tomonaga in 1950 that this principle is only valid in one-dimensional systems. Bosonization is an effective field theory that focuses on low-energy excitations.
Mathematical descriptions
A pair of chiral fermions , one being the conjugate variable of the other, can be described in terms of a chiral boson
where the currents of these two models are related by
where composite operators must be defined by a regularization and a subsequent renormalization.
Examples
In particle physics
The standard example in particle physics, for a Dirac field in (1+1) dimensions, is the equivalence between the massive Thirring model (MTM) and the quantum Sine-Gordon model. Sidney Coleman showed the Thirring model is S-dual to the sine-Gordon model. The fundamental fermions of the Thirring model correspond to the solitons (bosons) of the sine-Gordon model.
In condensed matter
The Luttinger liquid model, proposed by Tomonaga and reformulated by J.M. Luttinger, describes electrons in one-dimensional electrical conductors under second-order interactions. Daniel C. Mattis and Elliott H. Lieb proved in 1965 that electrons could be modeled as bosonic interactions. The response of the electron density to an external perturbation can be treated as plasmonic waves. This model predicts the emergence of spin–charge separation.
See also
Holstein–Primakoff transformation
References
Quantum field theory
Condensed matter physics | Bosonization | [
"Physics",
"Chemistry",
"Materials_science",
"Engineering"
] | 461 | [
"Quantum field theory",
"Matter",
"Phases of matter",
"Quantum mechanics",
"Materials science",
"Condensed matter physics",
"Quantum physics stubs"
] |
3,027,051 | https://en.wikipedia.org/wiki/Supersplit%20supersymmetry | Supersplit supersymmetry was conceived as an April Fool's Day joke in 2005 by a group of young theoretical high energy physicists. It was meant as a parody of split supersymmetry.
The model proposed particles (beyond those of the Standard Model) which are decoupled, leaving no trace at low energies, therefore leaving just the Standard Model. The paper argued that the 30% accuracy of gauge coupling unification in the Standard Model is on par with the 1% accuracy in the MSSM or Split Supersymmetry. It also used the well-known possibility that a Peccei-Quinn axion could be the dark matter of the universe.
As a serious scientific theory, it leads to no new predictions beyond the Standard Model, and is therefore unverifiable. As a social commentary, it demonstrates the uneasiness in the high energy physics community about the direction some model building is heading.
Despite the original intent as a ridiculous proposal, the original paper has been cited by few theoretical physicists.
Very recently, a paper by Giudice and Strumia has presented the same idea under the name 'high scale supersymmetry'.
References
External links
Supersplit Supersymmetry by P.J. Fox, D.E. Kaplan, E. Katz, E. Poppitz, V. Sanz, M. Schmaltz, M.D. Schwartz and N. Weiner
Supersymmetric quantum field theory
String theory
April Fools' Day jokes | Supersplit supersymmetry | [
"Physics",
"Astronomy"
] | 309 | [
"Astronomical hypotheses",
"Supersymmetric quantum field theory",
"Particle physics",
"Particle physics stubs",
"String theory",
"Supersymmetry",
"Symmetry"
] |
3,027,077 | https://en.wikipedia.org/wiki/Helicity%20%28particle%20physics%29 | In physics, helicity is the projection of the spin onto the direction of momentum.
Mathematically, helicity is the sign of the projection of the spin vector onto the momentum vector: "left" is negative, "right" is positive.
Overview
The angular momentum J is the sum of an orbital angular momentum L and a spin S. The relationship between orbital angular momentum L, the position operator r and the linear momentum (orbit part) p is
so L's component in the direction of p is zero. Thus, helicity is just the projection of the spin onto the direction of linear momentum. The helicity of a particle is positive (" right-handed") if the direction of its spin is the same as the direction of its motion and negative ("left-handed") if opposite.
Helicity is conserved. That is, the helicity commutes with the Hamiltonian, and thus, in the absence of external forces, is time-invariant. It is also rotationally invariant, in that a rotation applied to the system leaves the helicity unchanged. Helicity, however, is not Lorentz invariant; under the action of a Lorentz boost, the helicity may change sign. Consider, for example, a baseball, pitched as a gyroball, so that its spin axis is aligned with the direction of the pitch. It will have one helicity with respect to the point of view of the players on the field, but would appear to have a flipped helicity in any frame moving faster than the ball.
Comparison with chirality
In this sense, helicity can be contrasted
to chirality, which is Lorentz invariant, but is not a constant of motion for massive particles. For massless particles, the two coincide: The helicity is equal to the chirality, both are Lorentz invariant, and both are constants of motion.
In quantum mechanics, angular momentum is quantized, and thus helicity is quantized as well. Because the eigenvalues of spin with respect to an axis have discrete values, the eigenvalues of helicity are also discrete. For a massive particle of spin , the eigenvalues of helicity are , , , ..., −.
For massless particles, not all of spin eigenvalues correspond to physically meaningful degrees of freedom: For example, the photon is a massless spin 1 particle with helicity eigenvalues −1 and +1, but the eigenvalue 0 is not physically present.
All known spin particles have non-zero mass; however, for hypothetical massless spin particles (the Weyl spinors), helicity is equivalent to the chirality operator multiplied by . By contrast, for massive particles, distinct chirality states (e.g., as occur in the weak interaction charges) have both positive and negative helicity components, in ratios proportional to the mass of the particle.
A treatment of the helicity of gravitational waves can be found in Weinberg.
In summary, they come in only two forms: +2 and −2, while the +1, 0 and −1 helicities are "non-dynamical" (they can be removed by a gauge transformation).
Little group
In dimensions, the little group for a massless particle is the double cover of SE(2). This has unitary representations which are invariant under the SE(2) "translations" and transform as under a SE(2) rotation by . This is the helicity representation. There is also another unitary representation which transforms non-trivially under the SE(2) translations. This is the continuous spin representation.
In dimensions, the little group is the double cover of SE() (the case where is more complicated because of anyons, etc.). As before, there are unitary representations which don't transform under the SE() "translations" (the "standard" representations) and "continuous spin" representations.
See also
Chirality (physics)
Helicity basis
Gyroball, a macroscopic object (specifically a baseball) exhibiting an analogous phenomenon
Wigner's classification
Pauli–Lubanski pseudovector
References
Other sources
Quantum field theory | Helicity (particle physics) | [
"Physics"
] | 883 | [
"Quantum field theory",
"Quantum mechanics"
] |
3,027,085 | https://en.wikipedia.org/wiki/Boustrophedon%20transform | In mathematics, the boustrophedon transform is a procedure which maps one sequence to another. The transformed sequence is computed by an "addition" operation, implemented as if filling a triangular array in a boustrophedon (zigzag- or serpentine-like) manner—as opposed to a "Raster Scan" sawtooth-like manner.
Definition
The boustrophedon transform is a numerical, sequence-generating transformation, which is determined by a binary operation such as addition.
Generally speaking, given a sequence: , the boustrophedon transform yields another sequence: , where is likely defined equivalent to . The entirety of the transformation itself can be visualized (or imagined) as being constructed by filling-out the triangle as shown in Figure 1.
Boustrophedon Triangle
To fill-out the numerical Isosceles triangle (Figure 1), you start with the input sequence, , and place one value (from the input sequence) per row, using the boustrophedon scan (zigzag- or serpentine-like) approach.
The top vertex of the triangle will be the input value , equivalent to output value , and we number this top row as row 0.
The subsequent rows (going down to the base of the triangle) are numbered consecutively (from 0) as integers—let denote the number of the row currently being filled. These rows are constructed according to the row number () as follows:
For all rows, numbered , there will be exactly values in the row.
If is odd, then put the value on the right-hand end of the row.
Fill-out the interior of this row from right-to-left, where each value (index: ) is the result of "addition" between the value to right (index: ) and the value to the upper right (index: ).
The output value will be on the left-hand end of an odd row (where is odd).
If is even, then put the input value on the left-hand end of the row.
Fill-out the interior of this row from left-to-right, where each value (index: ) is the result of "addition" between the value to its left (index: ) and the value to its upper left (index: ).
The output value will be on the right-hand end of an even row (where is even).
Refer to the arrows in Figure 1 for a visual representation of these "addition" operations.
For a given, finite input-sequence: , of values, there will be exactly rows in the triangle, such that is an integer in the range: (exclusive). In other words, the last row is .
Recurrence relation
A more formal definition uses a recurrence relation. Define the numbers (with k ≥ n ≥ 0) by
.
Then the transformed sequence is defined by (for and greater indices).
Per this definition, note the following definitions for values outside the restrictions (from the relationship above) on pairs:
Special Cases
In the case a0 = 1, an = 0 (n > 0), the resulting triangle is called the Seidel–Entringer–Arnold Triangle and the numbers are called Entringer numbers .
In this case the numbers in the transformed sequence bn are called the Euler up/down numbers. This is sequence A000111 on the On-Line Encyclopedia of Integer Sequences. These enumerate the number of alternating permutations on n letters and are related to the Euler numbers and the Bernoulli numbers.
Algebraic definition(s)
Building from the geometric design of the boustrophedon transform, algebraic definitions of the relationship from input values () to output values () can be defined for different algebras ("numeric domains").
Euclidean (Real) values
In the Euclidean () Algebra for Real ()-valued scalars, the boustrophedon transformed Real-value is related to the input value, , as:
,
with the reverse relationship (input from output) defined as:
,
where is the sequence of "up/down" numbers—also known as secant or tangent numbers.
The exponential generating function
The exponential generating function of a sequence (an) is defined by
The exponential generating function of the boustrophedon transform (bn) is related to that of the original sequence (an) by
The exponential generating function of the unit sequence is 1, so that of the up/down numbers is sec x + tan x.
References
Integer sequences
Triangles of numbers
Permutations
Transforms | Boustrophedon transform | [
"Mathematics"
] | 937 | [
"Sequences and series",
"Functions and mappings",
"Integer sequences",
"Mathematical structures",
"Permutations",
"Recreational mathematics",
"Mathematical objects",
"Combinatorics",
"Mathematical relations",
"Triangles of numbers",
"Transforms",
"Numbers",
"Number theory"
] |
3,027,136 | https://en.wikipedia.org/wiki/786%20%28number%29 | 786 (seven hundred [and] eighty-six) is the natural number following 785 and preceding 787.
In mathematics
786 is:
a sphenic number.
a harshad number in bases 4, 5, 7, 14 and 16.
the aliquot sum of 510.
part of the 321329-aliquot tree. The complete aliquot sequence starting at 498 is: 498, 510, 786, 798, 1122, 1470, 2634, 2646, 4194, 4932, 7626, 8502, 9978, 9990, 17370, 28026, 35136, 67226, 33616, 37808, 40312, 35288, 37072, 45264, 79728, 146448, 281166, 281178, 363942, 424638, 526338, 722961, 321329, 1, 0
786 might be the largest n for which the value of the central binomial coefficient is not divisible by an odd prime squared. If there is a larger such number, it would have to be at least 157450 (see ).
In other fields
In the New General Catalogue, NGC786 is a magnitude 13.5 spiral galaxy in the constellation Aries. Additionally, 786 Bredichina is an asteroid.
In juggling, 786 as fourhanded Siteswap is also known as French threecount.
In culture
Indian Muslims associate the number with the basmala by summing up of all the numerical values of each Arabic letter making up the phrase. This auspiciousness has led it to often feature in films from the country.
Vijay Verma's (Amitabh Bachchan) coolie number in the 1975 Hindi film Deewaar.
Raja's (Rajnikanth) coolie number in the 1981 Tamil film Thee, a remake of Deewaar.
Iqbal Khan's (Amitabh Bachchan) coolie number in the 1983 Hindi film Coolie.
Bachchan has indicated that he believes the number is auspicious, as he survived a serious injury while wearing this number during the shooting of Coolie.
Chiranjeevi sported this number in the 1988 Telugu film Khaidi No.786.
Veer Pratap Singh's (Shahrukh Khan) prisoner number in the 2004 Hindi film Veer-Zaara.
Sultan's (Ajay Devgan) car in the 2010 Hindi film Once Upon a Time in Mumbaai bears the registration number MRH 786.
In the 2011 Tamil film Mankatha, in the scene where Vinayak Mahadev (Ajith Kumar) shoots Prem (Premgi Amaren), Prem wears has a gold plate on his chest with the number 786 written on it.
Ashish R Mohan's 2012 Hindi film Khiladi 786 features Akshay Kumar in the title role. The same film was released in Pakistan without the number 786.
References
External links
e-786.com Permissible to write 786
United Submitters analysis of 786
Integers | 786 (number) | [
"Mathematics"
] | 655 | [
"Elementary mathematics",
"Integers",
"Mathematical objects",
"Numbers"
] |
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