id int64 39 79M | url stringlengths 31 227 | text stringlengths 6 334k | source stringlengths 1 150 ⌀ | categories listlengths 1 6 | token_count int64 3 71.8k | subcategories listlengths 0 30 |
|---|---|---|---|---|---|---|
14,771,723 | https://en.wikipedia.org/wiki/PKNOX1 | PBX/Knotted 1 Homeobox 1 (PKNOX1) is a protein that in humans is encoded by the PKNOX1 gene.
An important paralog of this gene is PKNOX2.
Function
PKNOX1 belongs to the three amino acid loop extension (TALE) class of homeodomain transcription factors that form transcriptionally active complexes involved in development and organogenesis. PKNOX1 is essential for embryogenesis, but it can also act as a tumor suppressor in adulthood.
References
Further reading
External links
Transcription factors | PKNOX1 | [
"Chemistry",
"Biology"
] | 120 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,771,853 | https://en.wikipedia.org/wiki/Cav1.1 | {{DISPLAYTITLE:Cav1.1}}
Cav1.1 also known as the calcium channel, voltage-dependent, L type, alpha 1S subunit, (CACNA1S), is a protein which in humans is encoded by the CACNA1S gene. It is also known as CACNL1A3 and the dihydropyridine receptor (DHPR, so named due to the blocking action DHP has on it).
Function
This gene encodes one of the five subunits of the slowly inactivating L-type voltage-dependent calcium channel in skeletal muscle cells. Mutations in this gene have been associated with hypokalemic periodic paralysis, thyrotoxic periodic paralysis and malignant hyperthermia susceptibility.
Cav1.1 is a voltage-dependent calcium channel found in the transverse tubule of muscles. In skeletal muscle it associates with the ryanodine receptor RyR1 of the sarcoplasmic reticulum via a mechanical linkage. It senses the voltage change caused by the end-plate potential from nervous stimulation and propagated by sodium channels as action potentials to the T-tubules. It was previously thought that when the muscle depolarises, the calcium channel opens, allowing calcium in and activating RyR1, which mediates much greater calcium release from the sarcoplasmic reticulum. This is the first part of the process of excitation-contraction coupling, which ultimately causes the muscle to contract. Calcium entry through Cav1.1 is not required in skeletal muscle, as it is in cardiac muscle; Cav1.1 undergoes a conformational change which allosterically activates RyR1.
Clinical significance
In hypokalemic periodic paralysis (HOKPP), the voltage sensors in domains 2 and 4 of Cav1.1 are mutated (loss-of-function), reducing the availability of the channel to sense depolarisation, and therefore it cannot activate the ryanodine receptor as efficiently. As a result, the muscle cannot contract very well and the patient is paralysed. The condition is hypokalemic because a low extracellular potassium ion concentration will cause the muscle to repolarise to the resting potential more quickly, so any calcium conductance that does occur cannot be sustained. It becomes more difficult to reach the threshold at which the muscle can contract, and even if this is reached then the muscle is more prone to relaxing. Because of this, the severity would be reduced if potassium ion concentrations are maintained. In contrast, hyperkalemic periodic paralysis refers to gain-of-function mutations in sodium channels that maintain muscle depolarisation and therefore are aggravated by high potassium ion concentrations.
The European Malignant Hyperthermia Group accepts two mutations in CACNA1S as diagnostic for malignant hyperthermia.
Blockers
Cav1.1 is blocked by dihydropyridine.
See also
Calcium channel
Neuromuscular junction
Ryanodine receptor
References
Further reading
External links
GeneReviews/NCBI/NIH/UW entry on Malignant Hyperthermia Susceptibility
Ion channels | Cav1.1 | [
"Chemistry"
] | 661 | [
"Neurochemistry",
"Ion channels"
] |
14,771,908 | https://en.wikipedia.org/wiki/PROX1 | Prospero homeobox protein 1 is a protein that in humans is encoded by the PROX1 gene. The Prox1 gene is critical for the development of multiple
tissues. Prox1 activity is necessary and sufficient to specify a lymphatic endothelial cell fate in endothelial progenitors located in the embryonic veins.
Interactions
PROX1 has been shown to interact with EP300.
Production
PROX1 is produced primarily in the dentate gyrus in the mouse, and in the dentate gyrus and white matter in humans. Gene expression data for mouse, human and macaque from the Allen Brain Atlases can be found here.
Clinical significance
PROX1 is used as a marker for lymphatic endothelium in biopsy samples.
Homologous gene
PROX2
References
Further reading
External links
Transcription factors | PROX1 | [
"Chemistry",
"Biology"
] | 179 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,771,927 | https://en.wikipedia.org/wiki/GeneMark | GeneMark is a generic name for a family of ab initio gene prediction algorithms and software programs developed at the Georgia Institute of Technology in Atlanta. Developed in 1993, original GeneMark was used in 1995 as a primary gene prediction tool for annotation of the first completely sequenced bacterial genome of Haemophilus influenzae, and in 1996 for the first archaeal genome of Methanococcus jannaschii. The algorithm introduced inhomogeneous three-periodic Markov chain models of protein-coding DNA sequence that became standard in gene prediction as well as Bayesian approach to gene prediction in two DNA strands simultaneously. Species specific parameters of the models were estimated from training sets of sequences of known type (protein-coding and non-coding). The major step of the algorithm computes for a given DNA fragment posterior probabilities of either being "protein-coding" (carrying genetic code) in each of six possible reading frames (including three frames in the complementary DNA strand) or being "non-coding". The original GeneMark (developed before the advent of the HMM applications in Bioinformatics) was an HMM-like algorithm; it could be viewed as approximation to known in the HMM theory posterior decoding algorithm for appropriately defined HMM model of DNA sequence.
Further improvements in the algorithms for gene prediction in prokaryotic genomes
The GeneMark.hmm algorithm (1998) was designed to improve accuracy of prediction of short genes and gene starts. The idea was to use the inhomogeneous Markov chain models introduced in GeneMark for computing likelihoods of the sequences emitted by the states of a hidden Markov model, or rather semi-Markov HMM, or generalized HMM describing the genomic sequence. The borders between coding and non-coding regions were formally interpreted as transitions between hidden states. Additionally, the ribosome binding site model was added to the GHMM model to improve accuracy of gene start prediction. The next important step in the algorithm development was introduction of self-training or unsupervised training of the model parameters in the new gene prediction tool GeneMarkS (2001). Rapid accumulation of prokaryotic genomes in the following years has shown that the structure of sequence patterns related to gene expression regulation signals near gene starts may vary. Also, it was observed that prokaryotic genome may exhibit GC content variability due to the lateral gene transfer. The new algorithm, GeneMarkS-2 was designed to make automatic adjustments to the types of gene expression patterns and the GC content changes along the genomic sequence. GeneMarkS and, then GeneMarkS-2 have been used in the NCBI pipeline for prokaryotic genomes annotation (PGAP).
().
Heuristic Models and Gene Prediction in Metagenomes and Metatransciptomes
Accurate identification of species specific parameters of a gene finding algorithm is a necessary condition for making accurate gene predictions. However, in the studies of viral genomes one needs to estimate parameters from a rather short sequence that has no large genomic context. Importantly, starting 2004, the same question had to be addressed for gene prediction in short metagenomic sequences. A surprisingly accurate answer was found by introduction of parameter generating functions depending on a single variable, the sequence G+C content ("heurisic method" 1999). Subsequently, analysis of several hundred prokaryotic genomes led to developing more advanced heuristic method in 2010 (implemented in MetaGeneMark). Further on, the need to predict genes in RNA transcripts led to development of GeneMarkS-T (2015), a tool that identifies intron-less genes in long transcript sequences assembled from RNA-Seq reads.
Eukaryotic gene prediction
In eukaryotic genomes modeling of exon borders with introns and intergenic regions present a major challenge. The GHMM architecture of eukaryotic GeneMark.hmm includes hidden states for initial, internal, and terminal exons, introns, intergenic regions and single exon genes located in both DNA strands. Initial version of the eukaryotic GeneMark.hmm needed manual compilation of training sets of protein-coding sequences for estimation of the algorithm parameters. However, in 2005, the first self-training eukaryotic gene finder, GeneMark-ES, was developed. A fungal version of GeneMark-ES developed in 2008 features a more complex intron model and hierarchical strategy of self-training. In 2014, in GeneMark-ET the self-training of parameters was aided by extrinsic hints generated by mapping to the genome short RNA-Seq reads. Extrinsic evidence is not limited to the 'native' RNA sequences. The cross-species proteins collected in the vast protein databases could be a source for external hints, if the homologous relationships between the already known proteins and the proteins encoded by yet unknown genes in the novel genome are established. This task was solved upon developing the new algorithm, GeneMark-EP+ (2020). Integration of the RNA and protein sources of the intrinsic hints was done in GeneMark-ETP (2023). Versatility and accuracy of the eukaryotic gene finders of the GeneMark family have led to their incorporation into number of pipelines of genome annotation. Also, since 2016, the pipelines BRAKER1, BRAKER2, BRAKER3 were developed to combine the strongest features of GeneMark and AUGUSTUS.
Notably, gene prediction in eukaryotic transcripts can be done by the new algorithm GeneMarkS-T (2015)
GeneMark Family of Gene Prediction Programs
Bacteria, Archaea
GeneMark
GeneMarkS
GeneMarkS-2
Metagenomes and Metatranscriptomes
MetaGeneMark
GeneMarkS-T
Eukaryotes
GeneMark
GeneMark.hmm
GeneMark-ES: ab initio gene finding algorithm for eukaryotic genomes with automatic (unsupervised) training.
GeneMark-ET: augments GeneMark-ES by integrating RNA-Seq read alignments into the self-training procedure.
GeneMark-EP+: augments GeneMark-ES by iterative finding genes in a novel genome, detecting similarities of predicted genes to known proteins, splice-aligning of the known proteins to the genome and generating hints for the next round of prediction, and correction based on the external evidence.
GeneMark-ETP: integrates genomic, transcript and protein evidence into the gene prediction
Viruses, phages and plasmids
Heuristic models
Transcripts assembled from RNA-Seq read
GeneMarkS-T
See also
List of gene prediction software
Gene prediction
References
Borodovsky M. and McIninch J. "GeneMark: parallel gene recognition for both DNA strands." Computers & Chemistry (1993) 17 (2): 123–133. DOI
Lukashin A. and Borodovsky M. "GeneMark.hmm: new solutions for gene finding." Nucleic Acids Research (1998) 26 (4): 1107–1115. DOI PMID
Besemer J. and Borodovsky M. "Heuristic approach to deriving models for gene finding." Nucleic Acids Research (1999) 27 (19): 3911–3920. DOI PMID
Besemer J., Lomsadze A., and Borodovsky M. "GeneMarkS: a self-training method for prediction of gene starts in microbial genomes. Implications for finding sequence motifs in regulatory regions." Nucleic Acids Research (2001) 29 (12): 2607–2618. DOI PMID
Mills R., Rozanov M., Lomsadze A., Tatusova T., and Borodovsky M. "Improving gene annotation in complete viral genomes." Nucleic Acids Research (2003) 31 (23): 7041–7055. DOI PMID
Besemer J. and Borodovsky M. "GeneMark: web software for gene finding in prokaryotes, eukaryotes and viruses." Nucleic Acids Research (2005) 33 (Web Server Issue): W451-454. DOI PMID
Lomsadze A., Ter-Hovhannisyan V., Chernoff Y., and Borodovsky M. "Gene identification in novel eukaryotic genomes by self-training algorithm." Nucleic Acids Research (2005) 33 (20): 6494–6506. DOI PMID
Ter-Hovhannisyan V., Lomsadze A., Chernoff Y., and Borodovsky M. "Gene prediction in novel fungal genomes using an ab initio algorithm with unsupervised training." Genome Research (2008) 18 (12): 1979-1990. DOI PMID
Zhu W., Lomsadze A., and Borodovsky M. "Ab initio gene identification in metagenomic sequences." Nucleic Acids Research (2010) 38 (12): e132. DOI PMID
Lomsadze A., Burns P.D., and Borodovsky M. "Integration of mapped RNA-Seq reads into automatic training of eukaryotic gene finding algorithm." Nucleic Acids Research (2014) 42 (15): e119. DOI PMID
Tang S., Lomsadze A., and Borodovsky M. "Identification of protein coding regions in RNA transcripts." Nucleic Acids Research (2015) 43 (12): e78. DOI PMID
Tatusova T., DiCuccio M., Badretdin A., Chetvernin V., Nawrocki E., Zaslavsky L., Lomsadze A., Pruitt K., Borodovsky M., and Ostell J. "NCBI prokaryotic genome annotation pipeline." Nucleic Acids Research (2016) 44 (14): 6614-6624. DOI PMID
Hoff K., Lange S., Lomsadze A., Borodovsky M., and Stanke M. "BRAKER1: Unsupervised RNA-Seq-Based Genome Annotation with GeneMark-ET and AUGUSTUS." Bioinformatics (2016) 32 (5): 767-769. DOI PMID
Lomsadze A., Gemayel K., Tang S., and Borodovsky M. "Modeling leaderless transcription and atypical genes results in more accurate gene prediction in prokaryotes." Genome Research (2018) 28 (7): 1079-1089. DOI PMID
Bruna T., Hoff K., Lomsadze A., Stanke M., and Borodovsky M. "BRAKER2: automatic eukaryotic genome annotation with GeneMark-EP+ and AUGUSTUS supported by a protein database." NAR Genomics and Bioinformatics (2021) 3 (1): lqaa108 DOI PMID
Bruna T., Lomsadze A., and Borodovsky M. "GeneMark-EP+: eukaryotic gene prediction with self-training in the space of genes and proteins." NAR Genomics and Bioinformatics (2022) 2 (2): lqaa026 DOI PMID
Bruna T., Lomsadze A., and Borodovsky M. "GeneMark-ETP: Automatic Gene Finding in Eukaryotic Genomes in Consistence with Extrinsic Data." bioRxiv (Jan 5, 2023) DOI PMID
Gabriel L., Brůna T., Hoff K., Ebel M., Lomsadze A., Borodovsky M., and Stanke M. "BRAKER3: Fully automated genome annotation using RNA-Seq and protein evidence with GeneMark-ETP, AUGUSTUS and TSEBRA." bioRxiv (Nov 27, 2023) DOI PMID
External links
Metagenomics software
Mathematical and theoretical biology
Genomics
Bioinformatics software
zh:基因识别 | GeneMark | [
"Mathematics",
"Biology"
] | 2,528 | [
"Bioinformatics",
"Applied mathematics",
"Bioinformatics software",
"Mathematical and theoretical biology"
] |
14,772,106 | https://en.wikipedia.org/wiki/SEPP1 | Selenoprotein P is a protein that in humans is encoded by the SEPP1 gene.
This gene encodes a selenoprotein containing multiple selenocysteine (Sec) residues, which are encoded by the UGA codon that normally signals translation termination. The 3' UTR of selenoprotein genes have a common stem-loop structure, the sec insertion sequence (SECIS), which is necessary for the recognition of UGA as a Sec codon rather than as a stop signal. This selenoprotein is an extracellular glycoprotein, and is unusual in that it contains 10 Sec residues (human, rat, mouse) per polypeptide, one located at the C-terminal side of protein and others at the N-terminal side. It is a heparin-binding protein that appears to be associated with endothelial cells, and has been implicated to function as an antioxidant in the extracellular space. Several transcript variants, encoding either the same or different isoform, have been found for this gene.
Animal models
Mice and dogs with knock-out variants in their SEPP1 homologues (Selenop and SELENOP respectively) may develop cerebellar ataxia phenotypes. SEPP1 and neural precursor cell levels in mouse brains increase post-exercise. Mice engineered to lack SEPP1 did not increase neural precursors.
See also
Selenium in biology
References
Further reading
Selenoproteins | SEPP1 | [
"Chemistry"
] | 314 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,772,124 | https://en.wikipedia.org/wiki/Homeobox%20protein%20SIX1 | Homeobox protein SIX1 (Sine oculis homeobox homolog 1) is a protein that in humans is encoded by the SIX1 gene.
Function
The vertebrate SIX genes are homologs of the Drosophila 'sine oculis' (so) gene, which is expressed primarily in the developing visual system of the fly. Members of the SIX gene family encode proteins that are characterized by a divergent DNA-binding homeodomain and an upstream SIX domain, which may be involved both in determining DNA-binding specificity and in mediating protein–protein interactions. Genes in the SIX family have been shown to play roles in vertebrate and insect development or have been implicated in maintenance of the differentiated state of tissues.[supplied by OMIM]
Interactions
SIX1 has been shown to interact with EYA1, DACH, GRO and MDFI.
References
Further reading
Transcription factors | Homeobox protein SIX1 | [
"Chemistry",
"Biology"
] | 190 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,772,272 | https://en.wikipedia.org/wiki/UGT2B15 | UDP-glucuronosyltransferase 2B15 is an enzyme that in humans is encoded by the UGT2B15 gene.
The UGTs are of major importance in the conjugation and subsequent elimination of potentially toxic xenobiotics and endogenous compounds. UGT2B8 demonstrates reactivity with estriol. See UGT2B4 (MIM 600067).[supplied by OMIM]
References
Further reading | UGT2B15 | [
"Chemistry"
] | 100 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,772,277 | https://en.wikipedia.org/wiki/RAD18 | E3 ubiquitin-protein ligase RAD18 is an enzyme that in humans is encoded by the RAD18 gene. A knockout in a human colorectal cancer cell line, HCT116, has also been created.
Function
The protein encoded by this gene is highly similar to S. cerevisiae DNA damage repair protein Rad18. Yeast Rad18 functions through interaction with Rad6, which is a ubiquitin-conjugating enzyme required for post-replication repair of damaged DNA. Similar to its yeast counterpart, this protein is able to interact with the human homolog of yeast Rad6 protein through a conserved ring finger motif. Mutation of this motif results in defective replication of UV-damaged DNA and hypersensitivity to multiple mutagens.
Interactions
RAD18 has been shown to interact with HLTF, UBE2B and UBE2A.
References
Further reading
Genes mutated in mice
DNA repair | RAD18 | [
"Biology"
] | 199 | [
"Molecular genetics",
"DNA repair",
"Cellular processes"
] |
14,772,389 | https://en.wikipedia.org/wiki/KLRC4 | NKG2-F type II integral membrane protein is a protein that in humans is encoded by the KLRC4 gene.
Natural killer (NK) cells are lymphocytes that can mediate lysis of certain tumor cells and virus-infected cells without previous activation. They can also regulate specific humoral and cell-mediated immunity. NK cells preferentially express several calcium-dependent (C-type) lectins, which have been implicated in the regulation of NK cell function. KLRC4 is a member of the NKG2 group which are expressed primarily in natural killer (NK) cells and encodes a family of transmembrane proteins characterized by a type II membrane orientation (extracellular C terminus) and the presence of a C-type lectin domain. The NKG2 gene family is located within the NK complex, a region that contains several C-type lectin genes preferentially expressed on NK cells. The 3' end of the KLRC4 transcript includes the first non-coding exon found at the 5' end of the adjacent D12S2489E gene transcript.
References
Further reading | KLRC4 | [
"Chemistry"
] | 237 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,773,056 | https://en.wikipedia.org/wiki/ETV1 | ETS translocation variant 1 is a protein that in humans is encoded by the ETV1 gene.
References
Further reading
External links
Transcription factors | ETV1 | [
"Chemistry",
"Biology"
] | 31 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,773,127 | https://en.wikipedia.org/wiki/MERTK | Proto-oncogene tyrosine-protein kinase MER is an enzyme that in humans is encoded by the MERTK gene.
Function
This gene is a member of the TYRO3/AXL/MER (TAM) receptor kinase family and encodes a transmembrane protein with two fibronectin type-III domains, two Ig-like C2-type (immunoglobulin-like) domains, and one tyrosine kinase domain. Mutations in this gene have been associated with disruption of the retinal pigment epithelium (RPE) phagocytosis pathway and onset of autosomal recessive retinitis pigmentosa (RP).
References
Further reading
External links
GeneReviews/NCBI/NIH/UW entry on Retinitis Pigmentosa Overview
Tyrosine kinase receptors | MERTK | [
"Chemistry"
] | 177 | [
"Tyrosine kinase receptors",
"Signal transduction"
] |
14,773,279 | https://en.wikipedia.org/wiki/PPARGC1B | Peroxisome proliferator-activated receptor gamma coactivator 1-beta is a protein that in humans is encoded by the PPARGC1B gene.
See also
PPARGC1A
Peroxisome proliferator-activated receptor
Peroxisome proliferator-activated receptor alpha
Peroxisome proliferator-activated receptor delta
Peroxisome proliferator-activated receptor gamma
Transcription coregulator
References
Further reading
External links
Gene expression
Transcription coregulators | PPARGC1B | [
"Chemistry",
"Biology"
] | 102 | [
"Gene expression",
"Molecular genetics",
"Cellular processes",
"Molecular biology",
"Biochemistry"
] |
14,773,394 | https://en.wikipedia.org/wiki/GABRB1 | Gamma-aminobutyric acid receptor subunit beta-1 is a protein that in humans is encoded by the GABRB1 gene.
Function
The gamma-aminobutyric acid A receptor (GABAA receptor) is a multisubunit chloride channel that mediates the fastest inhibitory synaptic transmission in the central nervous system. This gene encodes GABA A receptor, beta 1 subunit. It is mapped to chromosome 4p12 in a cluster of genes encoding alpha 4, alpha 2 and gamma 1 subunits of the GABAA receptor. Alteration of this gene is implicated in the pathogenetics of schizophrenia.
Clinical significance
Mice bearing mutant copies of this gene have been shown to be vulnerable to binge drinking of alcohol.
See also
GABAA receptor
References
Further reading
External links
Ion channels | GABRB1 | [
"Chemistry"
] | 166 | [
"Neurochemistry",
"Ion channels"
] |
14,773,579 | https://en.wikipedia.org/wiki/HIC1 | Hypermethylated in cancer 1 protein is a protein that in humans is encoded by the HIC1 gene.
References
Further reading
External links
Transcription factors | HIC1 | [
"Chemistry",
"Biology"
] | 32 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,773,582 | https://en.wikipedia.org/wiki/Power%20transfer%20unit | In aviation, a power transfer unit (PTU) is a device that transfers hydraulic power from one of an aircraft's hydraulic systems to another in the event that the other system has failed or been turned off.
The PTU is used when, for example, there is right hydraulic system pressure but no left hydraulic system pressure. In this example, the PTU transfers hydraulic power from the right hydraulic system to the left hydraulic system. A PTU consists of a hydraulic motor paired with a hydraulic pump via a shaft.
As the connection is purely mechanical, there is no intermixing of hydraulic fluid between the left and right hydraulic systems during PTU operation.
Design philosophy
Large transport category aircraft with hydraulically powered flight controls and utilities typically have multiple, independent hydraulic systems powered by a combination of engine-driven and electrically driven hydraulic pumps. Multiple hydraulic systems are typically needed for redundancy, where for instance if one system fails or loses hydraulic fluid, a surviving system may still provide sufficient power for critical systems to continue safe flight and landing.
On airliners or business jets with powered flight controls, it is typical to have at least two hydraulic power control units (actuators) for each critical flight control surface — these are the elevators, rudder and ailerons. Only two sources might be used if some form of mechanical reversion is present (i.e. the pilot can still fly the aeroplane manually, but with some difficulty, via mechanical linkages and cables if hydraulic power is lost).
On fly-by-wire aircraft, at least three independent power sources are needed. Spoilers and flaps meanwhile are considered secondary flight controls, and may only have a single hydraulic power source, providing the flight control can be deployed symmetrically.
Likewise, landing gear, brakes and nosewheel steering are systems which are not considered critical for flight, and are subsequently typically only powered by a single hydraulic system on an airliner or business jet.
Where an aircraft utility is powered by a single hydraulic system, PTUs become beneficial in allowing a single source of power, e.g. a pump powered by one surviving engine, to power more than one hydraulic system if the source of power in that system has failed. PTUs only work on the proviso that the system has not punctured and lost its fluid, because they do not permit fluid transfer, only the transfer of mechanical work.
For example, on the original design of the Airbus A320, the landing gear hydraulics (extension/retraction, brakes and steering) were solely powered from the green (left hand) system, powered by the left-hand engine driven pump. In the event of a port engine failure during take-off, the landing gear would not be able to retract as there is no auxiliary motorpump in the green hydraulic system on an A320. (Modern A320s have the nosewheel steering powered by the yellow system.)
The PTU solves this problem by allowing a rotary mechanical coupling between both systems, so the engine driven pump for the yellow (right hand) system on the starboard engine, which is oversized for normal hydraulic demand, can dump the excess power into the green system via the PTU, and allow powered landing gear retraction to continue, while maintaining hydraulic pressure to the green system flight controls as well.
Assuring landing gear retraction in a failure case is one potential assurance provided by a PTU. Alternatively, the designer may elect to have a second electric motorpump perform this role if a PTU is not desired. An additional motorpump may be heavier than a PTU however, and complex trade studies may favor one option or the other, depending on which failure cases are considered and how important weight is in the trade-off.
Uni-directional & bi-directional PTUs
On the Airbus A320, the yellow system may power the green system, but because it is also bi-directional, if the starboard engine fails, the green system can help to power the yellow system by dumping excess power into it via the same mechanism. This is also known as a 'reversible' PTU.
On some other aircraft, the direction of rotation of the PTU, and thereby the fluid flow through it, may be designed to work in only one direction. The Citation X business jet is one such aircraft with a uni-directional PTU, protected by check-valves and a back-pressure stall line, designed to allow the right hand hydraulic system to assist the left hand hydraulic system and the left hand auxiliary motorpump to retract the landing gear during a port engine failure only.
On yet other aircraft, the function of a bi-directional reversible PTU can be accomplished with two uni-directional PTUs installed side-by-side arranged in opposite orientations to each other. The hydraulic system of the CH-47 Chinook helicopter uses twin uni-directional PTUs in this fashion.
In-line & bent-axis PTUs
Hydraulic power transfer units are essentially nothing more than a hydraulic motor coupled to a hydraulic pump via a shaft; as such, they can conceptually be any kind of motor or pump such as a vane, gear, impeller or an in-line piston, or a variable displacement in-line piston pump.
Commonly though, PTUs are paired in-line piston motors/pumps, in either bent or straight axis arrangements.
A straight-axis in-line piston pump/motor relies on a canted internal swashplate to drive the piston shoes up and down around the internal piston slipway of the pump, lubricated by the fluid itself — this kind of PTU may appear to resemble two cylinders bolted together, with an inlet and outlet port at either end. An example of a straight axis in-line PTU can be found in the Cessna Citation X hydraulic system.
A bent-axis in-line piston pump works the same way, but forgoes the canted swashplate; instead the whole rotating group is tilted to achieve the piston displacement. An example of a bent-axis in-line PTU can be found on the Hawker 4000 hydraulic system.
In yet further representations, a bent-axis fixed-displacement motor/pump can be mated with a straight-axis variable displacement motorpump, as in the case of the Airbus A320 PTU.
Mechanism of operation & distinctive noises
The mechanism by which a PTU works is by surging, PTUs self-start by pure mechanical influence alone resulting from the delta-pressure between the two hydraulic systems it is connected to. Consequently, a PTU accelerates very rapidly under the delta-P induced load, and then stops just as suddenly once the pressure equalizes. Each pressure surge may only be a second long, causing a stop-start mode of operation.
In practice, this results in a 'whoosh-whoosh' sudden spool up and spool down, which produces a loud noise that can be likened to a barking dog. Passengers who have flown on the Airbus A320 will frequently hear the PTU 'barking dog', generally when only one engine is running, or when the yellow system electric motorpump is the only active hydraulic power source; the PTU is mechanically activated in these cases. Consequently, the PTU is normally only heard on start-up or shut down. Very rarely is it heard in flight unless a momentary power deficit is present when retracting the gear, or a hydraulic fault has occurred.
In Airbus literature, it is stated that the PTU 'self-tests', on startup, however the PTU does not contain any electronic motor assistance and cannot be commanded to start; it starts by itself only when hydraulic pressure is present. However, solenoid energized shut-off valves can isolate the PTU via a push-button switch (pb/sw) in the cockpit, but this feature is rarely used.
Notes
External links
Video of Aer Lingus A320 start up, with characteristic PTU sound
Video of Airbus-PTU, working in its compartment
Hydraulics | Power transfer unit | [
"Physics",
"Chemistry"
] | 1,649 | [
"Physical systems",
"Hydraulics",
"Fluid dynamics"
] |
14,773,607 | https://en.wikipedia.org/wiki/HLF%20%28gene%29 | Hepatic leukemia factor is a protein that in humans is encoded by the HLF gene.
Function
This gene encodes a member of the proline and acidic-rich (PAR) protein family, a subset of the bZIP transcription factors. The encoded protein forms homodimers or heterodimers with other PAR family members and binds sequence-specific promoter elements to activate transcription. Chromosomal translocations fusing portions of this gene with the E2A gene cause a subset of childhood B-lineage acute lymphoid leukemias. Alternatively spliced transcript variants have been described, but their biological validity has not been determined.
References
Further reading
External links
Transcription factors | HLF (gene) | [
"Chemistry",
"Biology"
] | 141 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,773,643 | https://en.wikipedia.org/wiki/CRTC1 | CREB-regulated transcription coactivator 1 (CRTC1), previously referred to as TORC1 (), is a protein that in humans is encoded by the CRTC1 gene. It is expressed in a limited number of tissues that include fetal brain and liver and adult heart, skeletal muscles, liver and salivary glands and various regions of the adult central nervous system.
Clinical significance
Production of CRTC1 is blocked in Alzheimer's disease.
See also
Transcription coregulator
References
Further reading
External links
Gene expression
Transcription coregulators
Immunology
Alzheimer's disease research | CRTC1 | [
"Chemistry",
"Biology"
] | 120 | [
"Gene expression",
"Immunology",
"Molecular genetics",
"Cellular processes",
"Molecular biology",
"Biochemistry"
] |
14,773,744 | https://en.wikipedia.org/wiki/Protein%20AATF | Protein AATF, also known as apoptosis-antagonizing transcription factor is a protein that in humans is encoded by the AATF gene.
Function
The protein encoded by this gene was identified on the basis of its interaction with MAP3K12/DLK, a protein kinase known to be involved in the induction of cell apoptosis. This gene product contains a leucine zipper, which is a characteristic motif of transcription factors, and was shown to exhibit strong transactivation activity when fused to Gal4 DNA binding domain. Overexpression of this gene interfered with MAP3K12 induced apoptosis.
Interactions
Protein AATF has been shown to interact with:
PAWR,
POLR2J,
Retinoblastoma protein, and
Transcription factor Sp1.
References
Further reading
External links
Transcription factors | Protein AATF | [
"Chemistry",
"Biology"
] | 168 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,773,755 | https://en.wikipedia.org/wiki/HBP1 | HMG-box transcription factor 1, also known as HBP1, is a human protein.
Interactions
HBP1 has been shown to interact with SIN3A and Retinoblastoma protein.
References
Further reading
External links
Transcription factors | HBP1 | [
"Chemistry",
"Biology"
] | 52 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,773,824 | https://en.wikipedia.org/wiki/ATOX1 | ATOX1 is a copper metallochaperone protein that is encoded by the ATOX1 gene in humans. In mammals, ATOX1 plays a key role in copper homeostasis as it delivers copper from the cytosol to transporters ATP7A and ATP7B. Homologous proteins are found in a wide variety of eukaryotes, including Saccharomyces cerevisiae as ATX1, and all contain a conserved metal binding domain.
Function
ATOX1 is an abbreviation of the full name Antioxidant Protein 1. The nomenclature stems from initial characterization that showed that ATOX1 protected cells from reactive oxygen species. Since then, the primary role of ATOX1 has been established as a copper metallochaperone protein found in the cytoplasm of eukaryotes. A metallochaperone is an important protein that has metal trafficking and sequestration roles. As a metal sequestration protein, ATOX1 is capable of binding free metals in vivo, in order to protect cells from generation of reactive oxygen species and mismetallation of metalloproteins. As a metal trafficking protein, ATOX1 is responsible for shuttling copper from the cytosol to ATPase transporters ATP7A and ATP7B that move copper to the trans-Golgi network or secretory vesicles. In Saccharomyces cerevisiae, Atx1 delivers Cu(I) to a homologous transporter, Ccc2. The delivery of copper to ATPase transporters is vital for the subsequent insertion of copper into ceruloplasmin, a ferroxidase required for iron metabolism, within the golgi apparatus.
In addition to the metallochaperone function, recent reports have characterized ATOX1 as a cyclin D1 transcription factor.
Structure & metal coordination
ATOX1 has a ferrodoxin-like βαββαβ fold and coordinates to Cu(I) via a MXCXXC binding motif located in between the first β-sheet and α-helix. The metal binding motif is largely solvent exposed in Apo-ATOX1 and a conformational change is induced upon coordination to Cu(I). Cu(I) is coordinated in a distorted linear geometry to sulfurs of cystine to form a bond angle of 120°. The overall -1 charge of the primary coordination sphere is stabilized through the secondary coordination sphere that contains a proximal positively charged lysine. ATOX1 also binds Hg(II), Cd(II), Ag(I), and cisplatin via this motif, but a physiological role, if any, is not yet known.
Metal transfer
ATOX1 transfers Cu(I) to transporters ATP7A and ATP7B. Transfer occurs via a ligand exchange mechanism, where Cu(I) transiently adopts a 3-coordinate geometry with cysteine ligands from ATOX1 and the associated transporter. The ligand exchange mechanism allows for faster exchange than a diffusion mechanism and imparts specificity for both the metal and transporter. Since the ligand exchange accelerates that transfer and the reaction has a shallow thermodynamic gradient, it is said to be under kinetic control rather than thermodynamic control.
Clinical significance
Although there are presently no known diseases directly associated with ATOX1 malfunction, there is currently active research in a few areas:
There is a link between ATOX1 levels and sensitivity of cells for Pt-based drugs like cisplatin.
The mechanism of ammonium tetrathiomolybdate [NH4]2MoS4 treatment of Wilson's Disease is under review. Since ATOX1 forms a stable complex tetrathiomolybdate, it is being studied as the potential therapeutic target.
References
External links
Further reading
Proteins | ATOX1 | [
"Chemistry"
] | 802 | [
"Biomolecules by chemical classification",
"Proteins",
"Molecular biology"
] |
14,773,844 | https://en.wikipedia.org/wiki/HOXA7 | Homeobox protein Hox-A7 is a protein that in humans is encoded by the HOXA7 gene.
In vertebrates, the genes encoding the class of transcription factors called homeobox genes are found in clusters named A, B, C, and D on four separate chromosomes. Expression of these proteins is spatially and temporally regulated during embryonic development. This gene is part of the A cluster on chromosome 7 and encodes a DNA-binding transcription factor which may regulate gene expression, morphogenesis, and differentiation. For example, the encoded protein represses the transcription of differentiation-specific genes during keratinocyte proliferation, but this repression is then overcome by differentiation signals. This gene is highly similar to the antennapedia (Antp) gene of Drosophila.
See also
Homeobox
References
Further reading
External links
Transcription factors | HOXA7 | [
"Chemistry",
"Biology"
] | 177 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,773,867 | https://en.wikipedia.org/wiki/HOXA13 | Homeobox protein Hox-A13 is a protein that in humans is encoded by the HOXA13 gene.
Function
In vertebrates, the genes encoding the class of transcription factors called homeobox genes are found in clusters named A, B, C, and D on four separate chromosomes. Expression of these proteins is spatially and temporally regulated during embryonic development. This gene is part of the A cluster on chromosome 7 and encodes a DNA-binding transcription factor which may regulate gene expression, morphogenesis, and differentiation.
Clinical significance
Expansion of a polyalanine tract in the encoded protein can cause hand-foot-genital syndrome, also known as hand-foot-uterus syndrome. Aberrant expression of HoxA13 gene products in the esophagus, provokes Barrett’s esophagus, a form of metaplasia that is a direct precursor to esophageal cancer.
See also
Homeobox
References
Further reading
External links
GeneReviews/NCBI/NIH/UW entry on Hand-Foot-Genital Syndrome
Transcription factors | HOXA13 | [
"Chemistry",
"Biology"
] | 227 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,773,966 | https://en.wikipedia.org/wiki/KCNB1 | Potassium voltage-gated channel, Shab-related subfamily, member 1, also known as KCNB1 or Kv2.1, is a protein that, in humans, is encoded by the KCNB1 gene.
Potassium voltage-gated channel subfamily B member one, or simply known as KCNB1, is a delayed rectifier and voltage-gated potassium channel found throughout the body. The channel has a diverse number of functions. However, its main function, as a delayed rectifier, is to propagate current in its respective location. It is commonly expressed in the central nervous system, but may also be found in pulmonary arteries, auditory outer hair cells, stem cells, the retina, and organs such as the heart and pancreas. Modulation of K+ channel activity and expression has been found to be at the crux of many profound pathophysiological disorders in several cell types.
Potassium channels are among the most diverse of all ion channels in eukaryotes. With over 100 genes coding numerous functions, many isoforms of potassium channels are present in the body, but most are divided up into two main groups: inactivating transient channels and non-inactivating delayed rectifiers. Due to the multiple varied forms, potassium delayed rectifier channels open or close in response to a myriad of signals. These include: cell depolarization or hyperpolarization, increases in intracellular calcium concentrations, neurotransmitter binding, or second messenger activity such as G-proteins or kinases.
Structure
The general structure of all potassium channels contain a centered pore composed of alpha subunits with a pore loop expressed by a segment of conserved DNA, T/SxxTxGxG. This general sequence comprises the selectivity of the potassium channel. Depending on the channel, the alpha subunits are constructed in either a homo- or hetero-association, creating a 4-subunit selectivity pore or a 2-subunit pore, each with accessory beta subunits attached intracellularly. Also on the cytoplasmic side are the N- and C- termini, which play a crucial role in activating and deactivating KCNB1 channels. This pore creates the main opening of the channel where potassium ions flow through.
The type of pore domain (number of subunits) determines if the channel has the typical 6 transmembrane (protein) spanning regions, or the less dominant inward rectifier type of only 2 regions. KCNB1 has 6TM labeled S1-S6, each with a tetrameric structure. S5 and S6 create the p-loop, while S4 is the location of the voltage sensor. S4, along with S2 and S3 create the ‘activating’ portions of the delayed rectifier channel. The heteromeric complexes that contain the distinct pore are electrically inactive or non-conducting, but unlike other potassium families, the pore of the KCNB1 group has numerous phosphorylation sites allowing kinase activity. Maturing KCNB1 channels develop these phosphorylation sites within the channel pore, but lack a glycosylation stage in the N-terminus.
Specifically, the KCNB1 delayed rectifier channel conducts a potassium current (K+). This mediates high frequency firing due to the phosphorylation sites located within the channel via kinases and a major calcium influx typical of all neurons.
Kinetics
The kinetics surrounding the activation and deactivation of the KCNB1 channel is relatively unknown, and has been under considerable study. Three of the six transmembrane regions, S2, S3 and S4, contribute to the activation phase of the channel. Upon depolarization, the S4 region, which is positively charged, is moved in response to the subsequent positive charge of the depolarization. As a result of S4 movement, the negatively charged regions of S2 and S3 appear to move as well. The movement of these regions causes an opening of the channel gate within regions of S5 and S6. The intracellular regions of the C and N-terminus also play a crucial role in the activation kinetics of the channel. The two termini interact with one other, as the C-terminus folds around the N-terminus during channel activation. The relative movement between the N- and C- termini greatly aids in producing a conformational change of the channel necessary for channel opening. This interaction between these intracellular regions is believed to be linked with membrane-spanning regions of S1 and S6, and thus aid in the movement of S2, S3, and S4 in opening the channel. Studies on selective mutations knocking out these intracellular termini have been shown to produce larger reductions in speed and probability of channel opening, which indicates their importance in channel activation.
Function
Voltage-gated potassium (Kv) channels represent the most complex class of voltage-gated ion channels from both functional and structural standpoints. Delayed rectifier potassium channels’ most prevalent role is in the falling phase of physiological action potentials. KCNB1 rectifiers are also important in forming the cardiac beat and rate synchronicity that exists within the heart, and the lysis of target molecules in the immune response. These channels can also act as effectors in downstream signaling in G-protein coupled receptor transduction. KCNB1's regulation and propagation of current provides a means for regulatory control over several physiological functions. Their diverse functions include regulating neurotransmitter release, heart rate, insulin secretion, neuronal excitability, epithelial electrolyte transport, smooth muscle contraction, and apoptosis.
Voltage-gated potassium channels are essential in regulating neuronal membrane potential, and in contributing to action potential production and firing. In mammalian CNS neurons, KCNB1 is a predominant delayed rectifier potassium current that regulates neuronal excitability, action potential duration, and tonic spiking. This is necessary when it comes to proper neurotransmitter release, as such release is dependent on membrane potential. In mouse cardiomyocytes, KCNB1 channel is the molecular substrate of major repolarization current IK-slow2. Transgenic mice, expressing a dominant-negative isoform of KCNB1, exhibit markedly prolonged action potentials and demonstrate arrhythmia. KCNB1 also contributes to the function and regulation of smooth muscle fibers. Human studies on pulmonary arteries have shown that normal, physiological inhibition of KCNB1 current aids vasoconstriction of arteries. In human pancreatic ß cells, KCNB1, which mediates potassium efflux, produces a downstroke of the action potential in the cell. In effect, this behavior halts insulin secretion, as its activation decreases the Cav channel-mediated calcium influx that is necessary for insulin exocytosis. KCNB1 has also been found to promote apoptosis within neuronal cells. It is currently believed that KCNB1-induced apoptosis occurs in response to an increase in reactive oxygen species (ROS) that results either from acute oxidation or as a consequence of other cellular stresses.
Regulation
KCNB1 conductance is regulated primarily by oligomerization and phosphorylation. Additional forms of regulation include SUMOylation and acetylation, although the direct effect of these modifications is still under investigation. KCNB1 consensus sites in the N-terminus are not subject to glycosylation.
Phosphorylation
Many proteins undergo phosphorylation, or the addition of phosphate groups to amino acids subunits. Phosphorylation is modulated by kinases, which add phosphate groups, and phosphatases, which remove phosphate groups. In its phosphorylated state, KCNB1 is a poor conductor of current. There are 16 phosphorylation sites that are subject to the activity of kinases, such as cyclin-dependent kinase 5 and AMP-activated protein kinase. These sites are reversibly regulated by phosphatases such as, phosphatase calcineurin. Under periods of high electrical activity, depolarization of the neuron increases calcium influx and triggers phosphatase activity. Under resting conditions, KCNB1 tends to be phosphorylated. Phosphorylation raises the threshold voltage requirement for activation and allows microdomains to bind the channel, preventing KCNB1 from entering the plasma membrane. Microdomains localize KCNB1 in dendrites in cell bodies of hippocampal and cortical neurons. Conductance associated with de-phosphorylation of this channel acts to decrease or end periods high excitability. However, this relationship is not static and is cell dependent. The role of phosphorylation can be affected by reactive oxygen species (ROS) that increase during oxidative stress. ROS act to increase the levels of zinc (Zn2+) and calcium (Ca2+) intracellularly that act with protein kinases to phosphorylate certain sites on KCNB1. This phosphorylation increases the insertion of KCNB1 into the membrane and elevates conductance. Under these conditions the interaction with SNARE protein syntaxin, is enhanced. This surge of KCNB1 current induces activation of a pro-apoptotic pathway, DNA fragmentation, and caspase activation.
Oligomerization
Another proposed mechanism for regulation of apoptosis is oligomerization, or the process of forming multi-protein complexes held together through disulfide bonds. Under oxidative stress, reactive oxygen species (ROS) form and act to regulate KCNB1 through oxidation. Increase in oxygen radicals directly causes formation of KCNB1 oligomers that then accumulate in the plasma membrane and initially decrease current flow. Oligomer activation of c-Src and JNK kinases induces the initial pro-apoptotic signal, which is coupled to KCNB1 current. This further promotes the apoptosis pathway. KCNB1 oligomers have been detected in the post mortem human hippocampus
Blockers
Potassium delayed rectifiers have been implicated in many pharmacological uses in the investigation of biological toxins for drug development. A main component to many of the toxins with negative effects on delayed rectifiers contain cystine inhibitors that are arranged around disulfide bond formations. Many of these toxins originate from species of tarantulas. G. spatulata produces the hanatoxin, which was the first drug to be manipulated to interact with KCNB1 receptors by inhibiting the activation of most potassium voltage-gated channels. Other toxins, such as stromatoxin, heteroscordratoxin, and guangxitoxin, target the selectivity of voltage KCNB1 rectifiers, by either lowering potassium binding affinity or increasing the binding rate of potassium. This can lead to excitotoxicity, or overstimulation of postsynaptic neurons. In nature, the prey of tarantula that are injected with these endogenous toxins induces this excitotoxic effect, producing paralysis for easy capture. Physiologically, these venoms work on KCNB1 rectifier affinity by altering the channels’ voltage sensor, making it more or less sensitive to extracellular potassium concentrations. KCNB1 is also susceptible to tetraethylammonium (TEA) and 4-aminopyridine (4-AP), which completely block all channel activity. TEA also works on calcium-activated potassium channels, furthering its inhibitory effects on neurons and skeletal muscle. Some isoforms of TEA are beneficial for patients with severe Alzheimer's, as blocking KCNB1 channels reduces the amount of neuronal apoptosis, thereby slowing the rate of dementia. This has been attributed to the oxidative properties of the channel by ROS.
Physiological Role in Disease
Neurodegenerative Disease
Oxidative damage is widely considered to play a role in neurodegenerative disorders, including Alzheimer's disease. Such oxidative stress alters the redox sensitivity of the Kv2.1 delayed rectifier, resulting in the modulation of the channel. In vitro studies and studies in animal models show that when KCNB1 is oxidized, it no longer conducts, leading to neurons becoming hyperpolarized and dying; oxidized KCNB1 also clusters in lipid rafts and cannot be internalized, which also leads to apoptosis. These alterations disrupt normal neuronal signaling and increase the likelihood of neurological diseases. Oxidized (oligomerized) KCNB1 channels are present in the hippocampi of old (Braak stage 1-2) and Alzheimer's disease (Braak stage 5) donors of either sexes
As indicated earlier, oxidative and nitrosative injurious stimuli also activate a cell death-inducing cascade that promotes to a zinc and calcium/clamodulin-dependent interaction between syntaxin and Kv2.1, leading to the pro-apoptotic insertion of additional potassium channels into the plasma membrane. These new population of channels aid in the loss of intracellular potassium, creating a permissive environment for protease and nuclease activation in injured neurons. Agents that interfere with the Kv2.1/syntaxin interaction are highly neuroprotective in acute ischemic injury models (stroke)
Increased probability of the channel remaining open can also potentially drive neurodegeneration. Human immunodeficiency virus type-1 (HIV-1)-associated dementia (HAD) may be driven by an overabundance of glutamate, which in turn can trigger increased calcium levels, which in turn can drive calcium-dependent dephosphorylation of KCNB1 channels, which increases probability of channel activation and current conductance. Enhanced KCNB1 current couples cell shrinkage associated with apoptosis and dendritic beading leading to diminished long term potentiation. These neuronal modifications may explain the atrophy of cell layer volume and late stage cell death observed in HAD disease.
Cancer
Exploitation of this channel is advantageous in cancer cell survival as they have the ability to produce heme oxygenase-1, an enzyme with the ability to generate carbon monoxide (CO). Oncogenic cells benefit from producing CO due to the antagonizing effects of the KCNB1 channel. Inhibition of KCNB1 allows cancer proliferation without the apoptotic pathway preventing tumor formation. Although potassium channels are studied as a therapeutic target for cancer, this apoptotic regulation is dependent on cancer type, potassium channel type, expression levels, intracellular localization as well as regulation by pro- or anti-apoptotic factors.
Interactions
KCNB1 has been shown to interact with:
KCNH1, and
PTPRE.
See also
Voltage-gated potassium channel
Guangxitoxin
References
Further reading
External links
Ion channels | KCNB1 | [
"Chemistry"
] | 3,142 | [
"Neurochemistry",
"Ion channels"
] |
14,773,972 | https://en.wikipedia.org/wiki/KCNJ5 | G protein-activated inward rectifier potassium channel 4 (GIRK-4) is a protein that in humans is encoded by the KCNJ5 gene and is a type of G protein-gated ion channel.
Function
Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. The protein encoded by this gene is an integral membrane protein and inward-rectifier type potassium channel. The encoded protein, which has a greater tendency to allow potassium to flow into a cell rather than out of a cell, is controlled by G-proteins. It may associate with other G-protein-activated potassium channel subunits to form a heterotetrameric pore-forming complex.
In humans KCNJ5 is mainly expressed in adrenal gland and pituitary, although it is also detected at low levels in pancreas, spleen, lung, heart and brain. Consistent with this expression pattern, mutations in KCNJ5/Kir3.4 can cause familial hyperaldosteronism type III and a type of long QT syndrome.
Interactions
KCNJ5 has been shown to interact with KCNJ3.
See also
G protein-coupled inwardly-rectifying potassium channel
Inward-rectifier potassium ion channel
References
Further reading
External links
GTEX portal: KCNJ5 expression in human tissue
Ion channels | KCNJ5 | [
"Chemistry"
] | 292 | [
"Neurochemistry",
"Ion channels"
] |
14,774,346 | https://en.wikipedia.org/wiki/PPP3R1 | Calcineurin subunit B type 1 also known as protein phosphatase 2B regulatory subunit 1 is a protein that in humans is encoded by the PPP3R1 gene.
Clinical significance
The presence of a single nucleotide polymorphism rs1868402 in the PPP3R1 gene is strongly correlated with rapid progress of Alzheimer's disease.
References
Further reading
EF-hand-containing proteins | PPP3R1 | [
"Chemistry"
] | 88 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,774,442 | https://en.wikipedia.org/wiki/RFX5 | DNA-binding protein RFX5 is a protein that in humans is encoded by the RFX5 gene.
Function
A lack of MHC-II expression results in a severe immunodeficiency syndrome called MHC-II deficiency, or the bare lymphocyte syndrome (BLS; MIM 209920). At least 4 complementation groups have been identified in B-cell lines established from patients with BLS. The molecular defects in complementation groups B, C, and D all lead to a deficiency in RFX, a nuclear protein complex that binds to the Xbox of MHC-II promoters. The lack of RFX binding activity in complementation group C results from mutations in the RFX5 gene encoding the 75-kD subunit of RFX (Steimle et al., 1995). RFX5 is the fifth member of the growing family of DNA-binding proteins sharing a novel and highly characteristic DNA-binding domain called the RFX motif. Multiple alternatively spliced transcript variants have been found but the full-length natures of only two have been determined.
Interactions
RFX5 has been shown to interact with CIITA.
References
Further reading
External links
Transcription factors | RFX5 | [
"Chemistry",
"Biology"
] | 247 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,774,475 | https://en.wikipedia.org/wiki/60S%20ribosomal%20protein%20L6 | 60S ribosomal protein L6 is a protein that in humans is encoded by the RPL6 gene.
Ribosomes, the organelles that catalyze protein synthesis, consist of a small 40S subunit and a large 60S subunit. Together these subunits are composed of 4 RNA species and approximately 80 structurally distinct proteins. This gene encodes a ribosomal protein that is a component of the 60S subunit. The protein belongs to the L6E family of ribosomal proteins. It is located in the cytoplasm. The protein can bind specifically to domain C of the tax-responsive enhancer element of human T-cell leukemia virus type 1, and it has been suggested that the protein may participate in tax-mediated transactivation of transcription. As is typical for genes encoding ribosomal proteins, there are multiple processed pseudogenes of this gene dispersed through the genome. Two alternatively spliced transcript variants encoding the same protein have been found for this gene.
Interactions
RPL6 has been shown to interact with Basic fibroblast growth factor.
References
Further reading
Ribosomal proteins | 60S ribosomal protein L6 | [
"Chemistry"
] | 221 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,774,602 | https://en.wikipedia.org/wiki/McDonnell%20XV-1 | The McDonnell XV-1 is an experimental Convertiplane developed by McDonnell Aircraft for a joint research program between the United States Air Force and the United States Army to explore technologies to develop an aircraft that could take off and land like a helicopter but fly at faster airspeeds, similar to a conventional airplane. The XV-1 would reach a speed of , faster than any previous rotorcraft, but the program was terminated due to the tip-jet noise and complexity of the technology which gave only a modest gain in performance.
Development
In 1951, the Air Force announced a competition to develop a compound helicopter, an aircraft that could take off and land vertically, like a helicopter, but could cruise at higher airspeeds than conventional helicopters. The joint research program was being conducted by the Air Force's Research and Development Command and the Army's Transportation Corps. Bell Aircraft submitted the design for the XV-3, Sikorsky Aircraft submitted the S-57, a retracting rotor design, and McDonnell submitted a design modified from its Model M-28 design.
On 20 June 1951, the Air Force and Army signed a Letter of Intent with McDonnell to award a contract to develop an aircraft based on their design. McDonnell benefited from previous design work on the Model M-28 and had a complete mockup ready for inspection by the Army and Air Force by November 1951. McDonnell was given approval to begin fabrication of what was then designated the XL-25 ("L" for Liaison). As the aircraft was being constructed the designation was changed to XH-35. Finally, the aircraft became the first vehicle in the convertiplane series as the XV-1.
The basic airframe came from an early post-World War II commercial airplane program for a four-place airplane in the Bonanza and Navion class. McDonnell enlisted Kurt Hohenemser and Friedrich von Doblhoff, the Austrian helicopter designer of the WNF 342, to provide technical direction in developing the tip-jet driven rotor system. After 22 months of fabrication, the first aircraft (serial 53-4016) was ready for flight testing by early 1954.
Design
Built mostly from aluminum, the XV-1 fuselage consisted of a streamlined tube mounted on skid landing gear, with a rear-mounted engine and a pusher propeller. It also had tapered stub wings mounted high on the fuselage. In turn, twin tailbooms and twin vertical surfaces, interconnected by a horizontal stabilizer elevator, were mounted to the wings. A three-bladed main rotor powered by blade tip pressure jets was mounted on top of the fuselage, above the wing roots.
The convertiplane featured a single Continental-built R-975 radial piston engine that powered twin air compressors. These forced high-pressure air through piping in the rotor blades to a combustion chamber on each of the three rotor tips, where a burner ignited fuel for increased thrust, which drove the rotors around and allowed the aircraft to fly like a conventional helicopter.
For horizontal flight, the engine was disconnected from the compressors and drove the two-bladed pusher propeller instead. During forward flight the wing provided 80% of the lift with the remainder generated by the main rotor autorotating at about 50% of normal rpm. When in hover mode, the rotor turned at 410 RPM but slowed to 180 RPM for high-speed flight above .
The cabin was covered almost entirely with Plexiglas windows providing visibility in all directions except directly underneath the aircraft. The cockpit consisted of tandem pilot and copilot stations, or the aircraft could accommodate a pilot and three passengers, or a pilot and two stretchers.
Operational history
The XV-1 began tethered hovering flight tests on 11 February 1954, with test pilot John R. Noll. The tether had lead weights intended to keep the aircraft in ground effect until issues with the rotor's tip-jet propulsion system were solved. On 14 July 1954, the lead weights were removed and the XV-1 conducted its first free hovering flight. As flight testing continued, McDonnell completed the second machine (s/n 53-4017).
The second aircraft was modified from the original XV-1 in an attempt to reduce parasitic drag during high-speed forward flight. To achieve this end, the rotor pylon was reduced and the undercarriage was streamlined as well as strengthened. The second XV-1 also featured two small tail rotors mounted on the outboard side at the end of each tailboom. These were a result of the hover test flights by Noll who remarked on the lack of yaw authority when using rudders only. The original XV-1 would later be modified with the tail rotors.
By the spring of 1955, the second XV-1 was ready to join the flight program. On 29 April 1955, the XV-1 made its first transition from vertical to horizontal flight, and on 10 October 1955, the second XV-1 became the first rotorcraft to exceed , nearly faster than the helicopter speed record at the time. The XV-1 achieved a mu (the ratio of airspeed to rotor tip speed) of 0.95.
After three years and nearly 600 hours between the two aircraft, the XV-1 contract was canceled in 1957. Ultimately, it was determined that the XV-1's convertiplane configuration was too complex for the small advantages gained over conventional helicopters. The piston engine could not produce enough power to optimize the design advantages. Technological advances in conventional helicopter rotor design and engines in the following years would eventually negate the XV-1's performance margin. The noise level was 116 dB in the cockpit, but even higher for ground personnel who described the tip jet noise as "extremely irritating" and the noise level was still 90 dB away. McDonnell would try to capitalize on the tip-jet rotor technology with a small crane helicopter design, designated Model 120 and first flown on 13 November 1957.
Surviving aircraft
The Army retained 53-4016, which was transferred to the United States Army Aviation Museum at Fort Novosel, Alabama. 53-4017, the record-setting, second prototype, was donated by the Army to the Smithsonian Institution's National Air and Space Museum, Washington, D.C., in 1964.
Specifications (XV-1)
See also
References
Notes
Bibliography
Connor, R. and R. E. Lee. McDonnell XV-1 Convertiplane. 24 September 2001. Smithsonian National Air and Space Museum, Washington, DC. Accessed 4 December 2007.
Donald, David. The Complete Encyclopedia of World Aircraft. New York: Barnes & Noble Books, 1997. .
Francillon, René J. McDonnell Douglas Aircraft since 1920: Volume II. London: Putnam, 1997. .
Harding, Stephen. U.S. Army Aircraft Since 1947 An Illustrated Reference. Schiffer military/aviation history. Atglen, PA: Schiffer Pub, 1997. .
Markman, Steve, and William G. Holder. Straight Up A History of Vertical Flight. Schiffer military/aviation history. Atglen, PA: Schiffer Pub, 2000. .
Robb, Raymond L. Hybrid helicopters: Compounding the quest for speed, Vertiflite. Summer 2006. American Helicopter Society.
Harris, Franklin D. An Overview of Autogyros and the McDonnell XV–1 Convertiplane NASA, 2003. Mirror1, Mirror2. Size: 284 pages in 13MB
External links
McDonnell XV-1 XV-1 Convertiplane on Smithsonian National Air and Space Museum' site
XV-1 page on GlobalSecurity.org
XV-1 page on vstol.org
Early McDonnell Helicopters on AirandSpaceMuseum.org
Rotorcraft
Gyrodynes
1950s United States helicopters
XV-1
Single-engined pusher aircraft
Slowed rotor
Aircraft first flown in 1954
High-wing aircraft
Tipjet-powered helicopters
Aircraft with skid landing gear | McDonnell XV-1 | [
"Engineering"
] | 1,608 | [
"Slowed rotor",
"Aerospace engineering"
] |
14,774,731 | https://en.wikipedia.org/wiki/CACNB2 | Voltage-dependent L-type calcium channel subunit beta-2 is a protein that in humans is encoded by the CACNB2 gene.
Clinical significance
Mutation in the CACNB2 gene are associated with Brugada syndrome, autism, attention deficit-hyperactivity disorder (ADHD), bipolar disorder, major depressive disorder, and schizophrenia.
See also
Voltage-dependent calcium channel
References
Further reading
External links
GeneReviews/NIH/NCBI/UW entry on Brugada syndrome
Ion channels | CACNB2 | [
"Chemistry"
] | 106 | [
"Neurochemistry",
"Ion channels"
] |
14,774,797 | https://en.wikipedia.org/wiki/SUPT4H1 | Transcription elongation factor SPT4 is a protein that in humans is encoded by the SUPT4H1 gene.
References
Further reading | SUPT4H1 | [
"Chemistry"
] | 30 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,774,825 | https://en.wikipedia.org/wiki/TRG%20%28gene%29 | T cell receptor gamma locus is a protein that in humans is encoded by the TRG gene, also known as TCRG or TRG@. It contributes the gamma (γ) chain to the larger TCR protein (T-cell receptor).
Function
T cell receptors recognize foreign antigens which have been processed as small peptides and bound to major histocompatibility complex (MHC) molecules at the surface of antigen presenting cells (APC) (APC). Each T cell receptor is a dimer consisting of one alpha and one beta chain or one delta and one gamma chain. In a single cell, the T cell receptor loci are rearranged and expressed in the order delta, gamma, beta, and alpha. If both delta and gamma rearrangements produce functional chains, the cell expresses delta and gamma. If not, the cell proceeds to rearrange the beta and alpha loci. This region represents the germline organization of the T cell receptor gamma locus. The gamma locus includes V (variable), J (joining), and C (constant) segments. During T cell development, the gamma chain is synthesized by a recombination event at the DNA level joining a V segment with a J segment; the C segment is later joined by splicing at the RNA level. Recombination of many different V segments with several J segments provides a wide range of antigen recognition. Additional diversity is attained by junctional diversity, resulting from the random addition of nucleotides by terminal deoxynucleotidyl transferase. Several V segments of the gamma locus are known to be incapable of encoding a protein and are considered pseudogenes. Somatic rearrangement of the gamma locus has been observed in T cells derived from patients with T cell leukemia and ataxia telangiectasia.
Structure
In the αβ T cell lineage, these chains are disulfide-linked and noncovalently associated at the cell surface of T lymphocytes. While the αβ lineage has been widely studied, the γδ lineage has not due to the minimal number of defined antigens, the unusual cellular responses to their environment, and the resulting challenge of identifying and studying this population in vivo. Recombinant technology has allowed for the identification of the T-cell receptor gamma (TRG) gene that is found associated with the CD3 complex on the cell surface. As early as 1988, the structure and genetic basis of the γδ TCR was reported. The γ and δ chains can be either disulfide-linked or noncovalently attached.
The genomic sequence of the TRG locus has been determined in Canis lupus familiaris, with the Carnivora order hypothesized as the putative origin of the TRG locus. Forty genes were discovered of the following three types: variable (TRGV), joining (TRGJ), and constant (TRGC). These genes are organized into eight cassettes aligned with the same transcriptional orientation. Each cassette is composed of a V-J-J-C unit, except one with a J-J-C unit on the 3’ end of the locus. The canine locus is approximately 460 kb in length. Eight of the sixteen total TRGV genes, seven of the sixteen TRGJ genes, and six of the eight TRGC genes were determined to be functional. The locus organization of the TRG chain has been found to vary greatly across species and can be traced back evolutionarily. The human TRG locus is located on chromosome 7 and includes 14 variable segments, of which eight are potentially active, five joining segments, and two constant segments.
Function
T cells expressing the γ-chain (TRG+ cells) make up 3-10% of normal adult peripheral blood lymphocytes, with the majority (>80%) being of the Vγ2Vδ2+ subtype (referred to as Vδ2+ T cells). All TRG+ cells also express CD3, CD4, and CD8 complexes. While CD3 complexes have been associated with cytolytic regulation, it is unclear whether TRG is also necessary for mediated cellular cytotoxicity.
The function of the γ chain as well as the γδ dimer is still largely unknown, although they have been implicated in cytokine secretion and cytotoxic activity as a part of the protective immune system. The Vδ2+ T cells recognize small non-peptide antigens, but unlike αβ T cells, these antigens do not need to be processed by antigen-presenting cells or presented by classical major histocompatibility complex (MHC) molecules. This expansion in response to infections is specific to and more efficient in γδ T cells than αβ cells. There is a hypothesis that γδ T cells process these pathogenic antigens, transport them to draining lymph nodes, and then present the antigens to activate αβ T cells and other immune effectors. These Vδ2+ T cells have been reported to connect the innate and adaptive immune systems. Their innate effector functions include cell lysis and secretion of chemokines and cytokines, while their adaptive immunity functions include B cell help, DC maturation, and provision of memory T cells. Once activated these Vδ2+ T cells potentially mimic professional APCs by processing and presenting antigens. After activation, these cells may upregulate several antigen-presentation, adhesion, and co-stimulation molecules that mimic dendritic cells, a particular type of APC. These Vδ2+ T cells are exclusive to higher primates, indicating that they are responsible for protection against species-specific microbes.
Clinical significance
Deletions and mutations of the TRG gene have been implicated in a variety of cancers. Specifically, γδ T cells may contribute to the immune response against several tumor types (lymphoma, myeloma, breast, colon, lung, ovary, and others). They act directly through mediation of cytotoxic activity and indirectly through the regulation of other cell types responsible for the anti-tumor response. The presence of γδ T cells in the tumor microenvironment has been associated with poor prognosis in some cancers. This has led to the suggestion that these cells have plasticity and can respond to environmental cues. A potential mechanism is the downregulation of dendritic cell maturation, leading to immunosuppression.
While γδ T cells have been implicated in T cell lymphomas, there is also a specific subtype known as γδ T-cell lymphoma, characterized by the proliferation of those cells exclusively. This lymphoma can be quite aggressive with ulcerative plaques and subcutaneous nodules. In adenocarcinoma, polyclonal rearrangement of the TCR γ chain gene was significantly greater in N1 and N2 patients (using the TNM cancer staging system) than in N0 patients. Apart from carcinomas, TRG has also been correlated with hepatitis B virus (HBV). Specifically, Vδ2+ T cell levels and TCR γδ T cell cytotoxicity were significantly lower in patients with chronic HBV infections. These T cells may also play a role in immune cell reconstitution after hematopoietic stem cell transplantation, a procedure often used for cancers of the blood or bone marrow. The probability of post-procedure infections was significantly lower in patients with elevated levels of γδ T cells.
References
Further reading
Proteins | TRG (gene) | [
"Chemistry"
] | 1,574 | [
"Biomolecules by chemical classification",
"Proteins",
"Molecular biology"
] |
14,774,993 | https://en.wikipedia.org/wiki/HIST1H2AM | Histone H2A type 1 is a protein that in humans is encoded by the HIST1H2AM gene.
Histones are basic nuclear proteins that are responsible for the nucleosome structure of the chromosomal fiber in eukaryotes. Two molecules of each of the four core histones (H2A, H2B, H3, and H4) form an octamer, around which approximately 146 bp of DNA is wrapped in repeating units, called nucleosomes. The linker histone, H1, interacts with linker DNA between nucleosomes and functions in the compaction of chromatin into higher order structures. This gene is intronless and encodes a member of the histone H2A family. Transcripts from this gene lack polyA tails but instead contain a palindromic termination element. This gene is found in the small histone gene cluster on chromosome 6p22-p21.3.
References
Further reading | HIST1H2AM | [
"Chemistry"
] | 206 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,775,326 | https://en.wikipedia.org/wiki/MTA2 | Metastasis-associated protein MTA2 is a protein that in humans is encoded by the MTA2 gene.
MTA2 is the second member of the MTA family of genes. MTA2 protein localizes in the nucleus and is a component of the nucleosome remodeling and the deacetylation complex (NuRD). Similar to the founding family member MTA1, MTA2 functions as a chromatin remodeling factor and regulates gene expression. MTA2 is overexpressed in human cancer and its dysregulated level correlates well with cancer invasiveness and aggressive phenotypes.
Discovery
MTA2 was initially recognized as an MTA1 like 1 gene, named MTA1-L1, from a large scale sequencing of randomly selected clones from human cDNA libraries in 1999. Clues about the role of MTA2 in gene expression came from the association of MTA2 polypeptides in the NuRD complex in a proteomic study This was followed by targeted cloning of murine Mta2 in 2001.
Gene and spliced variants
MTA2 is localized on chromosome 11q12-q13.1 in human and on 19B in mice. The 8.6-kb long human MTA2 gene contains 20 exons and seven transcripts inclusive of three protein-coding transcripts but predicted to code for two polypeptides of 688 amino acids and 495 amino acids. The remaining four MTA2 transcripts are non-coding RNA transcripts ranging from 532-bp to 627-bp. The murine Mta2 consists of a 3.1-kb protein-coding transcript to code a protein of 668 amino acids, and five non-coding RNAs transcripts, ranging from 620-bp to 839-bp.
Structure
Amino acid sequence of MTA2 shares 68.2% homology with MTA1’s sequence. MTA2 domains include, a BAH (Bromo-Adjacent Homology), an ELM2 (egl-27 and MTA1 homology), a SANT domain (SWI, ADA2, N-CoR, TFIIIB-B), and a GATA-like zinc finger. MTA2 is acetylated at lysine 152 within the BAH domain
Function
This gene encodes a protein that has been identified as a component of NuRD, a nucleosome remodeling deacetylase complex identified in the nucleus of human cells. It shows a very broad expression pattern and is strongly expressed in many tissues. It may represent one member of a small gene family that encode different but related proteins involved either directly or indirectly in transcriptional regulation. Their indirect effects on transcriptional regulation may include chromatin remodeling.
MTA2 inhibits estrogen receptor-transactivation functions, and participates in the development of hormones independent of breast cancer cells. The MTA2 participate in the circadian rhythm through CLOCK-BMAL1 complex. MTA2 inhibits the expression of target genes owing to its ability to interact with chromatin remodeling complexes, and modulates pathways involved in cellular functions, including invasion, apoptosis, epithelial-to-mesenchymal transition, and growth of normal and cancer cells
Regulation
Expression of MTA2 is stimulated by Sp1 transcription factor and repressed by Kaiso. Growth regulatory activity of MTA2 is modulated through its acetylation by histone acetylase p300 [12]. The expression of MTA2 is inhibited by the Rho GDIa in breast cancer cells and by human β-defensins in colon cancer cells. MicroRNAs-146a and miR-34a also regulate the levels of MTA2 mRNA through post-transcriptional mechanism.
Targets
MTA2 deacetylates the estrogen receptor alpha and p53 and inhibits their transactivation functions. MTA2 represses the expression of E-cadherin in non-small-cell lung cancer cells. but stimulates the expression of IL-11 in gastric cancer cells. The MTA2-containing chromatin remodeling complex targets CLOCK-BMAL1 complex.
Interactions
MTA2 has been shown to interact with:
CHD4,
HDAC1,
HDAC2,
MBD3
MTA1,
RBBP4,
RBBP7, and
SATB1.
Notes
References
External links
Transcription factors | MTA2 | [
"Chemistry",
"Biology"
] | 931 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,775,368 | https://en.wikipedia.org/wiki/Elastration | Elastration (a portmanteau of "elastic" and "castration") is a bloodless method of male castration and docking commonly used for livestock. Elastration is simply banding the body part (scrotum or tail) until it drops off. This method is favored for its simplicity, low cost, and minimal training requirements.
Castration
Elastration is the most common method used to castrate sheep and goats, but is also common in cattle.
Procedure
Elastration involves restraining the animal, without the need for anesthesia or sedation (unlike most other castration methods), in a position that provides access to the genitals. Special elastrator pliers are then used to place a tight latex (rubber) elastrator ring gently around the base of the scrotum. This cuts the blood supply to the scrotum and testicles, which will totally decay and slough off within a few weeks. Care must be taken during the procedure to ensure that both testicles are fully descended and properly located inside the scrotum, and that the animal's nipples are not included within the ring. Elastration is normally limited to castrations done during the first few weeks of life, and it cannot be used for species where the scrotum does not have a narrow base, such as pigs or horses. It is commonly recommended to not use this method on goats until they are 8 weeks or older. This is due to possible complications that could occur later in life like urinary calculi. Goats that are banded during the first month of age are most at risk.
Possible complications
The country of Lithuania has banned the practice due to their belief that the procedure is inhumane. There is some evidence that elastration is more painful if carried out on older animals, although much of the immediate pain of application can be prevented by injection of local anaesthesia into the scrotal neck and testicles. Practitioners usually try to elastrate as soon as possible, once the testicles have descended, to reduce the amount of dead tissue, infection, and accompanying complications. However, with some animals such as goats, castrating too early increases the frequency of kidney stones and urinary problems due to reduced size of the urethra, so elastration may be postponed. If bull calves are castrated within the first one or two days the testes may sometimes be small and soft enough to be drawn up through the ring, and they continue to develop above the scrotum – surgical castration then becomes necessary.
Improper use of banding can result in death and charges of cruelty.
Docking
The same tool and rings are also used to dock the tails of many breeds of sheep, to prevent dung building up on the tails (which can lead to fly strike). This is usually done at the same time as castration of the ram lambs.
It is also called sheep marking in Australia and signaling in Argentina and Uruguay due to being done at the same time as the "signaling" or marking of the lambs' ears.
See also
Animal husbandry
Banding (medical)
Castration
Docking (animal)
References
Animal equipment
Theriogenology
Veterinary castration | Elastration | [
"Biology"
] | 653 | [
"Animal equipment",
"Animals"
] |
14,775,483 | https://en.wikipedia.org/wiki/ZBTB33 | Transcriptional regulator Kaiso is a protein that in humans is encoded by the ZBTB33 gene. This gene encodes a transcriptional regulator with bimodal DNA-binding specificity, which binds to methylated CGCG and also to the non-methylated consensus KAISO-binding site TCCTGCNA. The protein contains an N-terminal POZ/BTB domain and 3 C-terminal zinc finger motifs. It recruits the N-CoR repressor complex to promote histone deacetylation and the formation of repressive chromatin structures in target gene promoters. It may contribute to the repression of target genes of the Wnt signaling pathway, and may also activate transcription of a subset of target genes by the recruitment of catenin delta-2 (CTNND2). Its interaction with catenin delta-1 (CTNND1) inhibits binding to both methylated and non-methylated DNA. It also interacts directly with the nuclear import receptor Importin-α2 (also known as karyopherin alpha2 or RAG cohort 1), which may mediate nuclear import of this protein. Alternatively spliced transcript variants encoding the same protein have been identified.
NAMED by Dr.Juliet Daniel's, the KAISO gene was named after 'calypso' music popular in the Caribbeans, Trinidad & Tobago, e.t.c.
Interactions
ZBTB33 has been shown to interact with HDAC3, Nuclear receptor co-repressor 1 and CTNND1.
References
Further reading
External links
Transcription factors | ZBTB33 | [
"Chemistry",
"Biology"
] | 329 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,775,592 | https://en.wikipedia.org/wiki/OLIG2 | Oligodendrocyte transcription factor (OLIG2) is a basic helix-loop-helix (bHLH) transcription factor encoded by the OLIG2 gene. The protein is of 329 amino acids in length, 32 kDa in size and contains one basic helix-loop-helix DNA-binding domain. It is one of the three members of the bHLH family. The other two members are OLIG1 and OLIG3. The expression of OLIG2 is mostly restricted in central nervous system, where it acts as both an anti-neurigenic and a neurigenic factor at different stages of development. OLIG2 is well known for determining motor neuron and oligodendrocyte differentiation, as well as its role in sustaining replication in early development. It is mainly involved in diseases such as brain tumor and Down syndrome.
Function
OLIG2 is mostly expressed in restricted domains of the brain and spinal cord ventricular zone which give rise to oligodendrocytes and specific types of neurons. In the spinal cord, the pMN region sequentially generates motor neurons and oligodendrocytes. During embryogenesis, OLIG2 first directs motor neuron fate by establishing a ventral domain of motor neuron progenitors and promoting neuronal differentiation. OLIG2 then switches to promoting the formation of oligodendrocyte precursors and oligodendrocyte differentiation at later stages of development. Apart from functioning as a neurogenic factor in specification and the differentiation of motor neurons and oligodendrocytes, OLIG2 also functions as an anti-neurogenic factor at early time points in pMN progenitors to sustain the cycling progenitor pool. This side of anti-neurogenicity of OLIG2 later plays a bigger role in malignancies like glioma.
The role of phosphorylation has been highlighted recently to account for the multifaceted functions of OLIG2 in differentiation and proliferation. Studies showed that the phosphorylation state of OLIG2 at Ser30 determines the fate of cortical progenitor cells, in which cortical progenitor cells will either differentiate into astrocytes or remain as neuronal progenitors. Phosphorylation at a triple serine motif (Ser10, Ser13 and Ser14) on the other hand was shown to regulate the proliferative function of OLIG2. Another phosphorylation site Ser147 predicted by bioinformatics was found to regulate motor neuron development by regulating the binding between OLIG2 and NGN2. Further, OLIG2 contains a ST box composed of a string of 12 contiguous serine and threonine residues at position Ser77-Ser88. It is believed that phosphorylation at ST box is biologically functional, yet the role of it still remains to be elucidated in vivo.
OLIG2 has also been implicated in bovine horn ontogenesis. It was the only gene in the bovine polled locus to show differential expression between the putative horn bud and the frontal forehead skin.
Clinical Significance
OLIG2 in Cancer
OLIG2 is well recognized for its importance in cancer research, particularly in brain tumors and leukemia. OLIG2 is universally expressed in glioblastoma and other diffuse gliomas (astrocytomas, oligodendrogliomas and oligoastrocytomas), and is a useful positive diagnostic marker of these brain tumors. Although in normal brain tissue OLIG2 expresses mostly on oligodendrocytes but not on mature astrocytes, in adult glioma, OLIG2 expresses on both IDH1 or IDH2-mutant adult lower grade astrocytoma and oligodendroglioma on similar levels, but it is expressed on a lower level on IDH-wildtype glioblastoma. OLIG2 overexpression is a good surrogate marker for IDH mutation with an AUC of 0.90, but predicts poorly (AUC = 0.55) for 1p/19q co-deletion, a class-defining chromosomal alteration for oligodendroglioma. In survival analysis, higher mRNA levels of OLIG2 were associated with better overall survival, but this association was completely dependent on IDH mutation status.
In particular, OLIG2 is selectively expressed in a subgroup of glioma cells that are highly tumorigenic, and is shown to be required for proliferation of human glioma cells implanted in the brain of severe combined immunodeficiency (SCID) mice.
Though the molecular mechanism behind this tumorigenesis is not entirely clear, more studies have recently been published pinpointing diverse evidence and potential roles for OLIG2 in glioma progression. It is believed that OLIG2 promotes neural stem cell and progenitor cell proliferation by opposing p53 pathway, which potentially contributes to glioma progression. OLIG2 has been shown to directly repress the p53 tumor-suppressor pathway effector p21WAF1/CIP1, suppress p53 acetylation and impede the binding of p53 to several enhancer sites. It is further found that the phosphorylation of triple-serine motif in OLIG2 is present in several glioma lines and is more tumorigenic than the unphosphorylated status. In a study using the U12-1 cell line for controlled expression of OLIG2, researchers showed that OLIG2 can suppress the proliferation of U12-1 by transactivating the p27Kip1 gene and can inhibit the motility of the cell by activating RhoA.
Besides glioma, OLIG2 is also involved in leukemogenesis. The Olig2 gene was actually first identified in a study in T-cell acute lymphoblastic leukemia, in which the expression of OLIG2 was found elevated after t(14;21)(q11.2;q22) chromosomal translocation. The overexpression of OLIG2 was later shown present in malignancies beyond glioma and leukemia, such as breast cancer, melanoma and non-small cell lung carcinoma cell lines. It also has been shown that up-regulation of OLIG2 together with LMO1 and Notch1 helps to provide proliferation signals.
OLIG2 in Neural Diseases
OLIG2 is also associated with Down syndrome, as it locates at chromosome 21 within or near the Down syndrome critical region on the long arm. This region is believed to contribute to the cognitive defects of Down syndrome. The substantial increase in the number of forebrain inhibitory neurons often observed in Ts65dn mouse (a murine model of trisomy 21) could lead to imbalance between excitation and inhibition and behavioral abnormalities. However, genetic reduction of OLIG2 and OLIG1 from three copies to two rescued the overproduction of interneurons, indicating the pivotal role of OLIG2 expression level in Down syndrome. The association between OLIG2 and neural diseases (i.e. schizophrenia and Alzheimer's disease) are under scrutiny, as several single nucleotide polymorphisms (SNPs) associated with these diseases in OLIG2 were identified by genome-wide association work.
OLIG2 also plays a functional role in neural repair. Studies showed that the number of OLIG2-expressing cells increased in the lesion after cortical stab-wound injury, supporting the role for OLIG2 in reactive gliosis. OLIG2 was also implicated in generating reactive astrocytes possibly in a transient re-expression manner, but the mechanisms are unclear.
References
Further reading
External links
Transcription factors | OLIG2 | [
"Chemistry",
"Biology"
] | 1,612 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,775,823 | https://en.wikipedia.org/wiki/Centaurin%2C%20alpha%201 | Arf-GAP with dual PH domain-containing protein 1 is a protein that in humans is encoded by the ADAP1 gene.
Interactions
Centaurin, alpha 1 has been shown to interact with:
Casein kinase 1, alpha 1
Nucleolin,
P110α,
PRKCI,
Protein kinase D1, and
Protein kinase Mζ.
References
Further reading
Proteins | Centaurin, alpha 1 | [
"Chemistry"
] | 78 | [
"Biomolecules by chemical classification",
"Proteins",
"Molecular biology"
] |
14,775,986 | https://en.wikipedia.org/wiki/CLCN2 | Chloride channel protein 2 is a protein that in humans is encoded by the CLCN2 gene. Mutations of this gene have been found to cause leukoencephalopathy and Idiopathic generalised epilepsy (), although the latter claim has been disputed.
A gain of function mutation in the CLCN2 gene was found to cause primary aldosteronism, a form of arterial hypertension due to excessive production of aldosterone by the neuroendocrine cells of the zona glomerulosa of the adrenal gland. The mutation was found to cause a chloride leak in these cells and increased the expression of aldosterone synthase.
CLCN2 contains a transmembrane region that is involved in chloride ion transport as well two intracellular copies of the CBS domain.
See also
Chloride channel
References
Further reading
External links
Ion channels | CLCN2 | [
"Chemistry"
] | 181 | [
"Neurochemistry",
"Ion channels"
] |
14,776,022 | https://en.wikipedia.org/wiki/CLCN3 | H+/Cl− exchange transporter 3 is a protein that in humans is encoded by the CLCN3 gene.
Interactions
CLCN3 has been shown to interact with PDZK1.
See also
Chloride channel
References
Further reading
External links
Ion channels | CLCN3 | [
"Chemistry"
] | 54 | [
"Neurochemistry",
"Ion channels"
] |
14,776,038 | https://en.wikipedia.org/wiki/CLCN7 | Chloride channel 7 alpha subunit also known as H+/Cl− exchange transporter 7 is a protein that in humans is encoded by the CLCN7 gene. In melanocytic cells this gene is regulated by the Microphthalmia-associated transcription factor.
Clinical significance
Mutations in the CLCN7 gene have been reported to be associated with autosomal dominant osteopetrosis type II, a rare disease of bones.
See also
Chloride channel
References
Further reading
External links
GeneReviews/NCBI/NIH/UW entry on CLCN7-Related Osteopetrosis
Ion channels | CLCN7 | [
"Chemistry"
] | 128 | [
"Neurochemistry",
"Ion channels"
] |
14,776,057 | https://en.wikipedia.org/wiki/CLCNKB | Chloride channel Kb, also known as CLCNKB, is a protein which in humans is encoded by the CLCNKB gene.
Chloride channel Kb (CLCNKB) is a member of the CLC family of voltage-gated chloride channels, which comprises at least 9 mammalian chloride channels. Each is believed to have 12 transmembrane domains and intracellular N and C termini. Mutations in CLCNKB result in the autosomal recessive Type III Bartter syndrome. CLCNKA and CLCNKB are closely related (94% sequence identity), tightly linked (separated by 11 kb of genomic sequence) and are both expressed in mammalian kidney.
See also
Chloride channel
BSND, barttin, accessory subunit beta for this channel
References
Further reading
External links
Ion channels | CLCNKB | [
"Chemistry"
] | 165 | [
"Neurochemistry",
"Ion channels"
] |
14,776,101 | https://en.wikipedia.org/wiki/HAPLN1 | Hyaluronan and proteoglycan link protein 1 is a protein that in humans is encoded by the HAPLN1 gene.
Interactions
HAPLN1 has been shown to interact with Versican.
References
Further reading
Extracellular matrix proteins
Glycoproteins | HAPLN1 | [
"Chemistry"
] | 60 | [
"Glycoproteins",
"Glycobiology"
] |
14,776,154 | https://en.wikipedia.org/wiki/DLX5 | Homeobox protein DLX-5 is a protein that in humans is encoded by the distal-less homeobox 5 gene, or DLX5 gene. DLX5 is a member of the DLX gene family.
Function
This gene encodes a member of a homeobox transcription factor gene family similar to the Drosophila distal-less (Dll) gene. The encoded protein may play a role in bone development and fracture healing. Current research holds that the homeobox gene family is important in appendage development. DLX5 and DLX6 can be seen to work in conjunction and are both necessary for proper craniofacial, axial, and appendicular skeleton development. Mutations in this gene, which is located in a tail-to-tail configuration with DLX6 on the long arm of chromosome 7, may be associated with split-hand/split-foot malformation.
DLX5 also acts as the early BMP-responsive transcriptional activator needed for osteoblast differentiation by stimulating the up-regulation of a variety of promoters (ALPL promoter, SP7 promoter, MYC promoter).
Clinical significance
Mutations in the DLX5 gene have been shown to be involved in the split hand and foot malformation syndrome (SHFM). SHFM is a heterogenous limb defect in which the development of the central digital rays is hindered, leading to missing central digits and claw-like distal extremities. Other defects associated with DLX5 include sensorineural hearing loss, mental retardation, ectodermal and craniofacial findings, and orofacial clefting.
In mice, the targeted disruption of DLX1, DLX2, DLX1/2, or DLX5 orthologs yields craniofacial, bone, and vestibular defects. If DLX5 is disrupted in conjunction with DLX6, bone, inner ear, and severe craniofacial defects are prevalent. Research utilizing Dlx5/6-nulls suggests that these genes have both unique and redundant functions.
Role in development
DLX5 begins to express DLX5 protein in the facial and branchial arch mesenchyme, otic vesicles, and frontonasal ectoderm at around day 8.5-9. By day 12.5, DLX5 protein begins to be expressed in the brain, bones, and all remaining skeletal structures. Expression in the brain and skeleton begins to decrease by day 17.
Interactions
DLX5 has been shown to interact with DLX1, DLX2, DLX6, MSX1 and MSX2.
References
Further reading
External links
Transcription factors | DLX5 | [
"Chemistry",
"Biology"
] | 564 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,776,158 | https://en.wikipedia.org/wiki/Genmab | Genmab A/S is a Danish biotechnology company, founded in February 1999 by Florian Schönharting, at the time managing director of BankInvest Biomedical venture fund. The company is based in Copenhagen, Denmark – internationally, it operates through the subsidiaries Genmab B.V. in Utrecht, the Netherlands, Genmab U.S., Inc. in Princeton, New Jersey, US, and Genmab K.K. in Tokyo, Japan. Genmab is a dual-listed company with shares traded on both the Copenhagen Stock Exchange in Denmark and the NASDAQ Global Select Market in the US.
Technology
Genmab's technology is licensed from Medarex to create fully human high affinity antibodies using transgenic mice. These antibodies are less likely to elicit an allergic reaction and other side effects compared with other types of man-made antibodies containing other animal proteins because the IgG antibodies produced have human proteins. This technology is called the HuMab-Mouse technology. One benefit of using this type of technology is that there is no need for humanization or complicated genetic engineering to make this antibody fit for humans which cuts down on expenses and time spent developing it. It can be generated within months and can be selected to bind to specific antigens such as tumor cells and other infectious agents.
Genmab also has developed its own technology called UniBody, which is used to make smaller antibodies in contrast to the traditional full sized monoclonal antibody. Its smaller size allows for better distribution over larger target areas like tumors. The UniBody can only bind to one site and doesn’t elicit a harmful immune response by binding to two sites and over-activating cell growth. It does not kill target cells but rather silences or inhibits them. Thus it can be used to treat certain cancers, inflammations, allergies and asthmas, where killing the cell isn’t the objective.
The technology modifies the human IgG4 antibody. Normally the IgG4 is considered inert and doesn’t elicit an immune response. However, they are also unstable and fall apart easily, which makes them unsuitable for therapeutic use. Genmab changes the shape of the IgG4 antibody by eliminating the hinge, the part of the antibody that creates the “Y” shape. This halves the antibody, creating a smaller version now known as their UniBody. This smaller version can only bind to one site and does not stimulate cancer cells to grow.
History
Genmab was founded as a European spin-off of American Biotech company Medarex in February 1999. Danish investment firm BankInvest, under Florian Schönharting, provided the seed investment for the company to start up in Copenhagen. Like Medarex, Genmab began work producing monoclonal antibodies for life-threatening or debilitating diseases. Rising quickly in the Biotech world, Genmab attracted many investors, especially venture capital firms. The company went public in October 2000, earning DKK 1.56 billion, and had a second public offering in January 2006, yielding DKK 800 million.
The company's initial R&D location was a nine-story building in Utrecht Science Park, in the Netherlands; this was replaced with an "R&D Center" also in Utrecht, in June 2018. By mid-2019, this new facility was at capacity, and plans were set afoot to build an adjacent, connected facility.
By 2001, Medarex and Genmab had come back together in a drug development partnership, which highlighted the manufacturing deficit and clinical development expertise of Genmab relative to Medarex.
In 2005, the Biotechnology Industry Organization (BIO) and the Long Island Life Sciences Initiative honored Genmab with a James D. Watson Helix Award.
2008 saw the company purchasing a 22,000-litre, 36-acre antibody manufacturing plant in Brooklyn Park, Minnesota from PDL BioPharma, with plans to retain all 170 employees thereat. However, the company ran into financial trouble originating from several quarters, and a decision to sell the facility was reached in late 2009, after Genmab had started producing development scale batches from the facility. In 2008, the world was experiencing a financial crisis as a whole, and GlaxoSmithKline decided to exit oncology, which impacted co-development of ofatumumab, an oncology-directed product. In tandem with the sale of the plant, the company reorganized and planned to dismiss about 300 employees. Selling the facility, though, proved very difficult, due in large part to the global financial crisis; by 2012, Genmab had decided to simply write-off the entire facility from the company's balance sheets. A sale of the facility to Baxter came in February 2013.
Following the failed strategy of in-housing manufacturing, Genmab chose to thereafter completely outsource both manufacturing and the conduct of clinical trials.
The Company's first product, Arzerra (ofatumumab) reached the US market in 2009 for refractory chronic lymphocytic leukemia.
Executive history
Lisa N. Drakeman, Ph.D. had been a vice president at Medarex and wife of Donald Drakeman, Medarex's CEO and President at the time. Drakeman was one of Genmab's co-founders and was appointed chief executive officer (CEO) of the company upon incorporation in 1999, also joining the board of directors. , Drakeman remained in the CEO role, but by 2010 she had announced her retirement.
In 2010, Jan Van de Winkel, a co-founder of the firm, was appointed as President and CEO of Genmab. Since the company started in 1999, he had been Genmab's chief scientific officer (CSO); he had concurrently served as head of research, then president of R&D. , Van de Winkel remained CEO of the firm. Van de Winkel is a scientist, having produced more than 300 publications during his career.
Partnerships
Amgen: In May 1999, Genmab entered a sub-license agreement with Amgen where it would gain rights to the IL15 antibodies. In October 2001, this was replaced by a direct license agreement where Amgen retained exclusive commercialization options for the products through phase II. Amgen has also expanded its agreement to a new antibody program targeting additional disease targets. Amgen has discontinued development of the IL15 antibody, AMG 714, in psoriasis and rheumatoid arthritis based on disappointing results from recent clinical studies. Amgen is exploring options to maximize the value of this asset, but as this time, no further internal development of a lead indication is planned.
GlaxoSmithKline: In December 2006, Genmab entered a deal with GlaxoSmithKline to co-develop and commercialize ofatumumab, a drug that could be used for treatment in CD20 positive B-cell chronic lymphocytic leukemia, follicular non-Hodgkin’s lymphoma, rheumatoid arthritis and other indications. The agreement gave Genmab a license fee of DKK 582 million () and GSK bought 4,471,202 shares of Genmab for DKK 2,033 million (). The potential value of this agreement could be DKK 12.0 billion () if all milestones are reached and commercial success is reached in the fields of cancer, autoimmune, and inflammatory disease. The intention of GlaxoSmithKline to exit oncology, disagreement around milestones reached, and financial difficulties of Genmab, led to re-negotiation of the partnership in mid-2010, resulting in an immediate payment by GlaxoSmithKline and future financial and licensing concessions on the part of Genmab.
In addition, Genmab has collaborations with Roche (RG1507, a monoclonal antibody directed against IGF-1R, collaboration was terminated in 2009)
In April 2024, the company announced it would acquire ProfoundBio for $1.8 billion.
Products
The company has 8 approved antibodies (monoclonal and bispecific) used in 8 marketed products, covering cancer indications and autoimmune diseases.
Proprietary, marketed with partners:
Epkinly/Tepkinly (epcoritamab) for the treatment of Relapsed/refractory diffuse large B-cell lymphoma (DLBCL) (AbbVie)
Tivdak (tisotumab vedotin) for the treatment of previously treated recurrent or metastatic cervical cancer (Seagen)
Marketed by partners:
Darzalex (IV) (daratumumab) / Darzalex Faspro (SC) (daratumumab and hyaluronidase) for the treatment of all stages of multiple myeloma as combination therapy or monotherapy, and for the treatment of newly diagnosed amyloid light-chain (AL) amyloidosis (Janssen)
Kesimpta (ofatumumab) for the treatment of relapsing remitting multiple sclerosis (Novartis)
Rybrevant (amivantamab) for the treatment of non-small-cell lung cancer (EGFR exon 20 insertion mutations) (Janssen)
Talvey (talquetamab) for the treatment of relapsed/refractory MM (Janssen)
Tecvayli (teclistamab) for the treatment of relapsed/refractory MM (Janssen)
Tepezza (teprotumumab) for the treatment of thyroid eye disease (Horizon)
Furthermore both Genmab and its partners have a whole range of antibody programs, building on Genmab technologies, in clinical and pre-clinical development in both cancer and autoimmune diseases.Genmab have several late stage clinical programs for tisotumab vedotin (cervical cancer, ovarian cancer and solid tumors) and epcoritamab (B-cell non-Hodgkin lymphoma and Relapsed/refractory Follicular lymphoma).The partners have, among others, clinical programs for daratumumab (non-MM blood cancers), amivantamab (gastric cancer and esophageal cancer), Mim8 (Factor VIII mimetic bi-specific antibody) (Haemophilia A), inclacumab (VOC in Sickle cell disease) and teprotumumab (diffuse cutaneous systemic sclerosis).
Pipeline
Proprietary Products
Approved Medicines/Products
Pipeline, Including Further Development for Approved Medicines
Programs Incorporating Genmab’s Innovation and Technology
Approved Medicines/Products
Pipeline, Partner-owned products incorporating Genmab’s innovation, ≥Phase 2 Development
References
Companies listed on Nasdaq Copenhagen
Companies listed on the Nasdaq
Pharmaceutical companies of Denmark
Biotechnology companies of Denmark
Life science companies based in Copenhagen
Pharmaceutical companies established in 1999
Biotechnology companies established in 1999
Danish companies established in 1999
Danish brands
Dual-listed companies
Companies based in Copenhagen Municipality
Companies in the OMX Copenhagen 25
Companies in the OMX Nordic 40 | Genmab | [
"Biology"
] | 2,326 | [
"Life sciences industry",
"Life science companies based in Copenhagen"
] |
14,776,520 | https://en.wikipedia.org/wiki/GLUDP5 | Glutamate dehydrogenase pseudogene 5, also known as GLUDP5, is a human gene.
References
Further reading
Pseudogenes | GLUDP5 | [
"Chemistry"
] | 34 | [
"Biochemistry stubs",
"Protein stubs"
] |
9,633,147 | https://en.wikipedia.org/wiki/Sarcomastigophora | The phylum Sarcomastigophora belongs to the Protista or protoctista kingdom and it includes many unicellular or colonial, autotrophic, or heterotrophic organisms. It is characterized by flagella, pseudopodia, or both.
Taxonomy
It is divided into three subphyla: the Mastigophora, the Sarcodina and the Opalinata.
It is polyphyletic, and it is not a universally recognized classification. It places great significance upon method of locomotion in generating the taxonomy.
It can be described either as:
kingdom Protista → phylum Sarcomastigophora
or in older classifications as
phylum Protozoa → subphylum Sarcomastigophora.
Characteristics
It gets its name from the combination of "Sarcodina" (which is an older term used for amoeboids) and "Mastigophora" (which is an older term for flagellates).
The characteristics of phylum sarcomastigophora are :
(1) Nucleus is of one type except in the stages of certain foraminifera.
(2) Locomotory organ either pseudopodia or flagella or both.
(3) Reproduction asexual, but when sexually it is essentially by syngamy
Example : Amoeba, Euglena etc.
See also
Protozoa
Foraminifera
Radiolaria
Red Tide
Volvox
References
External links
Obsolete eukaryote taxa
Eukaryote phyla
Polyphyletic groups | Sarcomastigophora | [
"Biology"
] | 321 | [
"Phylogenetics",
"Polyphyletic groups"
] |
9,633,335 | https://en.wikipedia.org/wiki/Gauss%E2%80%93Codazzi%20equations | In Riemannian geometry and pseudo-Riemannian geometry, the Gauss–Codazzi equations (also called the Gauss–Codazzi–Weingarten-Mainardi equations or Gauss–Peterson–Codazzi formulas) are fundamental formulas that link together the induced metric and second fundamental form of a submanifold of (or immersion into) a Riemannian or pseudo-Riemannian manifold.
The equations were originally discovered in the context of surfaces in three-dimensional Euclidean space. In this context, the first equation, often called the Gauss equation (after its discoverer Carl Friedrich Gauss), says that the Gauss curvature of the surface, at any given point, is dictated by the derivatives of the Gauss map at that point, as encoded by the second fundamental form. The second equation, called the Codazzi equation or Codazzi-Mainardi equation, states that the covariant derivative of the second fundamental form is fully symmetric. It is named for Gaspare Mainardi (1856) and Delfino Codazzi (1868–1869), who independently derived the result, although it was discovered earlier by Karl Mikhailovich Peterson.
Formal statement
Let be an n-dimensional embedded submanifold of a Riemannian manifold P of dimension . There is a natural inclusion of the tangent bundle of M into that of P by the pushforward, and the cokernel is the normal bundle of M:
The metric splits this short exact sequence, and so
Relative to this splitting, the Levi-Civita connection of P decomposes into tangential and normal components. For each and vector field Y on M,
Let
The Gauss formula now asserts that is the Levi-Civita connection for M, and is a symmetric vector-valued form with values in the normal bundle. It is often referred to as the second fundamental form.
An immediate corollary is the Gauss equation for the curvature tensor. For ,
where is the Riemann curvature tensor of P and R is that of M.
The Weingarten equation is an analog of the Gauss formula for a connection in the normal bundle. Let and a normal vector field. Then decompose the ambient covariant derivative of along X into tangential and normal components:
Then
Weingarten's equation:
DX is a metric connection in the normal bundle.
There are thus a pair of connections: ∇, defined on the tangent bundle of M; and D, defined on the normal bundle of M. These combine to form a connection on any tensor product of copies of TM and T⊥M. In particular, they defined the covariant derivative of :
The Codazzi–Mainardi equation is
Since every immersion is, in particular, a local embedding, the above formulas also hold for immersions.
Gauss–Codazzi equations in classical differential geometry
Statement of classical equations
In classical differential geometry of surfaces, the Codazzi–Mainardi equations are expressed via the second fundamental form (L, M, N):
The Gauss formula, depending on how one chooses to define the Gaussian curvature, may be a tautology. It can be stated as
where (e, f, g) are the components of the first fundamental form.
Derivation of classical equations
Consider a parametric surface in Euclidean 3-space,
where the three component functions depend smoothly on ordered pairs (u,v) in some open domain U in the uv-plane. Assume that this surface is regular, meaning that the vectors ru and rv are linearly independent. Complete this to a basis {ru,rv,n}, by selecting a unit vector n normal to the surface. It is possible to express the second partial derivatives of r (vectors of ) with the Christoffel symbols and the elements of the second fundamental form. We choose the first two components of the basis as they are intrinsic to the surface and intend to prove intrinsic property of the Gaussian curvature. The last term in the basis is extrinsic.
Clairaut's theorem states that partial derivatives commute:
If we differentiate ruu with respect to v and ruv with respect to u, we get:
Now substitute the above expressions for the second derivatives and equate the coefficients of n:
Rearranging this equation gives the first Codazzi–Mainardi equation.
The second equation may be derived similarly.
Mean curvature
Let M be a smooth m-dimensional manifold immersed in the (m + k)-dimensional smooth manifold P. Let be a local orthonormal frame of vector fields normal to M. Then we can write,
If, now, is a local orthonormal frame (of tangent vector fields) on the same open subset of M, then we can define the mean curvatures of the immersion by
In particular, if M is a hypersurface of P, i.e. , then there is only one mean curvature to speak of. The immersion is called minimal if all the are identically zero.
Observe that the mean curvature is a trace, or average, of the second fundamental form, for any given component. Sometimes mean curvature is defined by multiplying the sum on the right-hand side by .
We can now write the Gauss–Codazzi equations as
Contracting the components gives us
When M is a hypersurface, this simplifies to
where and . In that case, one more contraction yields,
where and are the scalar curvatures of P and M respectively, and
If , the scalar curvature equation might be more complicated.
We can already use these equations to draw some conclusions. For example, any minimal immersion into the round sphere must be of the form
where runs from 1 to and
is the Laplacian on M, and is a positive constant.
See also
Darboux frame
Notes
References
Historical references
("General Discussions about Curved Surfaces")
.
Textbooks
do Carmo, Manfredo P. Differential geometry of curves & surfaces. Revised & updated second edition. Dover Publications, Inc., Mineola, NY, 2016. xvi+510 pp.
do Carmo, Manfredo Perdigão. Riemannian geometry. Translated from the second Portuguese edition by Francis Flaherty. Mathematics: Theory & Applications. Birkhäuser Boston, Inc., Boston, MA, 1992. xiv+300 pp.
Kobayashi, Shoshichi; Nomizu, Katsumi. Foundations of differential geometry. Vol. II. Interscience Tracts in Pure and Applied Mathematics, No. 15 Vol. II Interscience Publishers John Wiley & Sons, Inc., New York-London-Sydney 1969 xv+470 pp.
O'Neill, Barrett. Semi-Riemannian geometry. With applications to relativity. Pure and Applied Mathematics, 103. Academic Press, Inc. [Harcourt Brace Jovanovich, Publishers], New York, 1983. xiii+468 pp.
Articles
Simons, James. Minimal varieties in riemannian manifolds. Ann. of Math. (2) 88 (1968), 62–105.
External links
Peterson–Mainardi–Codazzi Equations – from Wolfram MathWorld
Peterson–Codazzi Equations
Differential geometry of surfaces
Riemannian geometry
Curvature (mathematics)
Surfaces | Gauss–Codazzi equations | [
"Physics"
] | 1,491 | [
"Geometric measurement",
"Physical quantities",
"Curvature (mathematics)"
] |
9,633,614 | https://en.wikipedia.org/wiki/Delay%20equalization | In signal processing, delay equalization corresponds to adjusting the relative phases of different frequencies to achieve a constant group delay, using by adding an all-pass filter in series with an uncompensated filter. Clever machine-learning techniques are now being applied to the design of such filters.
References
Signal processing
Digital signal processing | Delay equalization | [
"Technology",
"Engineering"
] | 66 | [
"Telecommunications engineering",
"Computer engineering",
"Signal processing"
] |
9,633,678 | https://en.wikipedia.org/wiki/Baptist%20Mills%2C%20Bristol | Baptist Mills an area of the city of Bristol, England. The name derives from the former mills which stood in that area.
Geology
The solid geology of Baptist Mills comprises Triassic Redcliffe Sandstone, which is overlain by superficial deposits of Quaternary alluvium in the floodplain of the Horfield Brook and the River Frome.
History
Baptist Mills is so named from the mills that once stood there. A grist (flour) mill is recorded in this area in a document written in 1470, and again in 1610, when they are marked on Chester and Master's Map of Kingswood.
The mills were converted to brass mills by the Bristol Brass Company, formed in 1702 by Abraham Darby, Edward lloyd, John Andrews, and Arthur Thomas. In 1706, further partners were admitted, the business becoming an early unincorporated joint stock company with a capital of £8000. While there, Darby recruited skilled 'Dutchmen' to operate a brass battery with trip hammers. He may also have recruited men skilled in sand moulding as opposed to the loam moulding hitherto used in England. Darby was the active partner in the business, but later withdrew to concentrate on his new ironfounding business at Coalbrookdale.
Brass production at the Baptist Mills Brass Works ceased in 1814, and in 1839 parts of the former brass works were acquired Joseph and James White, who established a factory manufacturing "Egyptian Black" pottery, Rockingham teapots and clay tobacco pipes. By 1861 the business was known as the Phoenix Pottery. The pottery closed at some point after 1891.
The last remains of the brass works were destroyed when Junction 3 of the M32 Motorway was constructed in the early 1970s. However, slag blocks made from waste from the works can be found in the area.
References
Areas of Bristol
Non-ferrous metallurgical works in the United Kingdom
Places formerly in Gloucestershire | Baptist Mills, Bristol | [
"Chemistry"
] | 390 | [
"Non-ferrous metallurgical works in the United Kingdom",
"Metallurgical facilities"
] |
9,633,736 | https://en.wikipedia.org/wiki/Insulin%20tolerance%20test | An insulin tolerance test (ITT) is a medical diagnostic procedure during which insulin is injected into a patient's vein, after which blood glucose is measured at regular intervals. This procedure is performed to assess pituitary function, adrenal function, insulin sensitivity, and sometimes for other purposes. An ITT is usually ordered and interpreted by an endocrinologist.
When used to assess insulin sensitivity, a standard dose of insulin is administered, and blood glucose is monitored with frequent sampling. The plasma glucose disappearance rate (KITT) indicates the degree of whole-body insulin sensitivity, and correlates well with the gold-standard glucose clamp technique.
When used for assessing the integrity of the hypothalamic–pituitary–adrenal axis (HPA), insulin injections are continued to the point of inducing extreme hypoglycemia below 2.2 mmol/L (40 mg/dL). Patient must have symptomatic neuroglycopenia to trigger counter-regulatory cascade. Glucose levels below 2.2 mmol/L are insufficient absent symptoms. The brain must register low glucose levels. In response, adrenocorticotropic hormone (ACTH) and growth hormone (GH) are released as a part of the stress mechanism. ACTH elevation causes the adrenal cortex to release cortisol. Normally, both cortisol and GH serve as counterregulatory hormones, opposing the action of insulin, i.e. acting against the hypoglycemia.
ITT to the point of extreme hypoglycemia is considered to be the gold standard for assessing the integrity of the HPA. Sometimes ITT is performed to assess the adrenal function, e.g. before surgery. It is assumed that the ability to respond to insulin-induced hypoglycemia translates into appropriate cortisol rise in the stressful event of acute illness or major surgery. The extreme hypoglycemic version of the ITT is potentially very dangerous and must be undertaken with great care, because it can iatrogenically induce the equivalent of a diabetic coma. A health professional must attend it at all times. Other provocation tests which cause much less release of growth hormone include the use of glucagon, arginine and clonidine.
Side effects
Side effects include sweating, palpitations, loss of consciousness and rarely convulsions due to severe hypoglycemia which may cause coma. If extreme symptoms are present, glucose should be given intravenously. In subjects with no adrenal reserve an Addisonian crisis may occur. For cortisol stimulation, the ACTH stimulation test has much less risk.
Contraindications
Insulin tolerance test contraindications are:
This test should not be performed on children outside a specialist pediatric endocrine unit.
Ischemic heart disease
Epilepsy
Severe panhypopituitarism, hypoadrenalism
Hypothyroidism impairs the GH and cortisol response. Patients should have corticosteroid replacement commenced prior to thyroxine as the latter has been reported to precipitate an Addisonian crisis with dual deficiency. If adrenal insufficiency is confirmed, the need for a repeat ITT may need to be reconsidered after 3 months thyroxine therapy.
Interpretation
The test cannot be interpreted unless hypoglycaemia (< 2.2 mmol/L (or) < 40 mg/dL) is achieved.
Hypopituitarism
An adequate cortisol response is defined as a rise to greater than 550 nmol/L. Patients with impaired cortisol responses (less than 550 but greater than 400 nmol/L) may only need steroid cover for major illnesses or stresses. An adequate GH response occurs with an absolute response exceeding 20 mU/L.
Cushing's syndrome
There will be a rise of less than 170 nmol/L above the fluctuations of basal levels of cortisol.
See also
ACTH stimulation test
Hypopituitarism
Triple bolus test
References
Blood tests
Pediatrics
Dynamic endocrine function tests | Insulin tolerance test | [
"Chemistry"
] | 873 | [
"Blood tests",
"Chemical pathology"
] |
9,634,115 | https://en.wikipedia.org/wiki/Business%20informatics | Business informatics (BI) is a discipline combining economics, the economics of digitization, business administration, accounting, internal auditing, information technology (IT), and concepts of computer science. Business informatics centers around creating programming and equipment frameworks which ultimately provide the organization with effective operation based on information technology application. The focus on programming and equipment boosts the value of the analysis of economics and information technology. The BI discipline was created in Germany (in German: Wirtschaftsinformatik). It is an established academic discipline, including bachelor, master, diploma, and PhD programs in Austria, Belgium, Egypt, France, Germany, Hungary, Ireland, The Netherlands, Russia, Slovakia, Sweden, Switzerland, and Turkey, and is establishing itself in an increasing number of other countries as well, including Finland, Australia, Bosnia and Herzegovina, Malaysia, Mexico, Poland, India and South Africa.
Business informatics as an integrative discipline
Business informatics shows similarities to information systems (IS), which is a well-established discipline originating in North America. However, there are a few differences that make business informatics a unique discipline:
Business informatics includes information technology, like the relevant portions of applied computer science, to a significantly larger extent than information systems do.
Business informatics includes significant construction and implementation-oriented elements. Another thing is one major focus lies in the development of solutions for business problems rather than the ex post investigation of their impact.
Information systems (IS) focus on empirically explaining the phenomena of the real world. Information systems has been said to have an "explanation-oriented" focus in contrast to the "solution-oriented" focus that dominates business informatics. Information systems researchers make an effort to explain the phenomena of acceptance and influence of IT in organizations and society by applying an empirical approach. In order to do that, usually qualitative and quantitative empirical studies are conducted and evaluated. In contrast to that, business informatics researchers mainly focus on the creation of IT solutions for challenges they have observed or assumed, and thereby they focus more on the possible future uses of IT.
Tight integration between research and teaching following the Humboldtian ideal a major goal in business informatics. Insights gained in actual research projects become part of the curricula quite quickly since most researchers are also lecturers at the same time. The pace of scientific and technological progress in business informatics is quite rapid; therefore, subjects taught are under permanent reconsideration and revision. In its evolution, the business informatics discipline is fairly young. Therefore, significant hurdles have to be overcome in order to further establish its vision.
Career prospects
Specialists in business informatics can work both in research and in commerce. In business, there are various uses, which may vary depending on professional experience. Fields of employment may include:
Management consulting
Information technology consulting
IT account manager
Systems analysis and organization
Business analyst
IT project manager
IT auditor
Solution architect
Enterprise architect
Information technology management
In consulting, a clear line must be drawn between strategic and IT consulting.
Tertiary Institutions Providing Business Informatics Degree
University of Louisiana at Lafayette
Idaho State University
Northern Kentucky College
University of South Africa (Unisa)
There are more and more universities and community colleges providing business informatics degree.
Journal
Business & Information Systems Engineering
See also
Bachelor of Business Information Systems
Master of Business Informatics
References
Academic disciplines
Information systems
Information technology management | Business informatics | [
"Technology"
] | 677 | [
"Information systems",
"Information technology",
"Information technology management"
] |
9,634,133 | https://en.wikipedia.org/wiki/Local%20insertion | In broadcasting, local insertion (known in the United Kingdom as an opt-out) is the act or capability of a broadcast television station, radio station or cable system to insert or replace part of a network feed with content unique to the local station or system. Most often this is a station identification (required by the broadcasting authority such as the U.S. Federal Communications Commission), but is also commonly used for television or radio advertisements, or a weather or traffic report. A digital on-screen graphic ("dog" or "bug"), commonly a translucent watermark, may also be keyed (superimposed) with a television station ID over the network feed using a character generator using genlock. In cases where individual broadcast stations carry programs separate from those shown on the main network, this is known as regional variation (in the United Kingdom) or an opt-out (in Canada and the United States).
Automated local insertion used to be triggered with in-band signaling, such as DTMF tones or sub-audible sounds (such as 25 Hz), but is now done with out-of-band signaling, such as analog signal subcarriers via communications satellite, or now more commonly via digital signals; broadcast automation equipment can then handle these automatically. In an emergency, such as severe weather, local insertion may also occur instantly through command from another network or other source (such as the Emergency Alert System or First Warning). In this case, the most urgent warning messages may interrupt without delay, while others may be worked into a normal break in programming within 15 minutes of their initial issuance.
Within individual programs
In the United States, insertion can easily be heard every evening on the nationally syndicated radio show Delilah, where the host does a pre-recorded station-specific voiceover played over a music bed from the network. When host Delilah Rene says "this is Delilah", her voice (often in a slightly different tone or mood than what she has just been speaking) then identifies the branding or identification for the specific station (for example, "on B98.5 FM" when heard on WSB-FM in Atlanta, Georgia). Because of this slight difference in vocal quality, many syndicated radio networks suggest using only one voice for local station IDs 24/7; this way, the difference in vocal intonation is lessened. Insertion is made conspicuous when, due to carelessness, or even abuse—e.g. to squeeze in one more ad—the network program is already underway by the time the insert closes. This same mode of insertion is heard during weather forecasts transmitted by outside companies such as Weatherology, where all the audio assets, including three to four days of upcoming weather, temperatures, wind direction/speed and the current conditions and possible warnings are pre-recorded, then matched together to form the audio of a full forecast.
The other more prominent example is during live sports programming carried over radio and television networks, where close to the top of the hour, a play-by-play announcer will say "we pause ten seconds for station identification; this is the (team name) (radio network branding)", or a close equivalent. On most stations, this is a basic station identification, as required by the Federal Communications Commission (FCC), with the call letters and city of license relayed, while on others a quickly-read five second advertisement or program promotion is read before the identification, or a breaking news event or weather warning occurring during the event is relayed, followed by the station ID. Due to many sports rights deals for televised sports moving to regional sports networks which are not required to identify themselves under FCC guidelines, or network sports coverage where the station is identified through an on-screen display by the local station rather than speech, this is more prominent on radio rather than television.
Local commercial (and some non-commercial) broadcast television stations also insert local commercial breaks during programming each half-hour while network-supplied or syndicated content is being broadcast. Television networks and syndication distributors give their affiliates either 60, 90 or 120 seconds each half-hour (typically totaling about four minutes per hour) to run local station breaks, including promos for the station and advertisements for national and local area businesses (and on a few stations, local news updates – which were particularly common during the 1970s through the 1990s, especially as the "24 Hour News Source" format became commonplace in the United States during the latter decade – current time and temperature information, or a brief local weather forecast), over network programming. Typically, these networks air a blank feed showing the network's logo (such as with Fox, NBC, The CW, and MyNetworkTV) or a series of public service announcements (as with ABC and CBS), while stations air local commercials. PBS member stations and other non-commercial educational stations also insert promos for network series and/or syndicated or locally produced programming during promo breaks; as these station are non-commercial, breaks are typically not featured during the programs themselves, instead promos are inserted in-between shows, even – in the case of PBS members – if the station is carrying the national network feed.
Various television morning news shows (such as Good Morning America and Today) also allocate five minutes of programming time each half-hour for stations to carry a local news update at :25 and :55 minutes past the hour; however the national feed continues for stations that do not wish to "break away", either because they do not air a morning newscast or simply do not have a news department (for example, some mid-sized and smaller market NBC affiliates, such as KTEN in Ada, Oklahoma, do not air news cut-ins during the weekend edition of Today if they do not have a weekend morning newscast, but cut-ins are shown during the weekday telecasts where Today follows a morning newscast). This also occurs with news on NPR's Morning Edition and All Things Considered, which respectively air during the morning and evening rush hours. For commercial stations in the 2020s, the news and weather update, which was traditionally 2-3 minutes in the past, now may run only as long as a condensed one minute at most, with the rest of the allocation devoted to local advertising.
Starting in the early 1990s, some cable television systems began carrying a local insert called "Local Edition", a segment featuring local news inserts (which are produced by area television stations or local cable operators) that air at :24 and :54 minutes past the hour during HLN's rolling daytime news block, usually during the network's non-essential features news block. This has been discontinued as that network has switched to a general news/talk format beginning in 2005.
Transmitter identification
Translator stations may also have local insertion, though this is generally limited to identifying the repeating station's callsign and community of license separate from its parent station. In the United States, the FCC also allows up to 30 seconds each hour for fundraising to keep the translator service on the air.
Pay television
Local insertion is also used by cable and telephone company television providers, in which cable and telco headends insert advertisements for the system, promotions for programs on other cable channels carried by the provider and commercials for local area businesses (such as car dealerships or furniture stores) at least twice each hour; unlike most commercial broadcast stations, however, cable channels often run only 60 seconds of local commercial inserts each half-hour near the end of the first or second commercial break and are aired in place of national ads or network promos that air during that given time. Direct-broadcast satellite services take advantage of the hard drive space on consumer digital video recorders to upload service-specific advertising and promotions localized to the customer's market area, though consumers with non-DVR units instead have default service advertising and promos.
Local insertion on cable television is used especially on The Weather Channel in the U.S. and The Weather Network/MétéoMédia in Canada, where systems like the WeatherStar, IntelliStar and PMX have been used to show regularly scheduled local weather forecasts (known as "Local on the 8s" on The Weather Channel in the U.S.), and well as the lower display line (LDL) or lower-third graphic that is shown at other times. The Weather Channel, in particular also airs ads during national breaks at the end of some advertisements allowing its WeatherSTAR or IntelliSTAR systems to insert selected locations for certain businesses operating in the area, such as restaurants or auto rental dealers; though The Weather Channel has not done this as much in recent years as they have in the past. This only applies to the cable systems, although in the U.S. direct-broadcast satellite services have shown an LDL of the current conditions and 12-hour forecast for select major cities. This is not seen on older TVRO or "big ugly dish" systems, as this is intended as a backhaul and has very few end-users, and is used as a clean feed, though some cable services which have not upgraded to the channel's HD systems may see the national overview instead while the standard definition broadcast remains localized.
Set-top boxes
In place of the IntelliSTAR, a hyperlocal form of insertion is now done on DirecTV (and possibly other DBS services), whereby the first half of the local forecast is generated by the set-top box. A "cutout" at the upper right corner of the picture allows the sponsor's advertising logo to be shown live from the main video feed, while a datacast on the satellite (like that which provides the electronic program guide) sends simple forecast and conditions data for the entire country every couple of minutes. Graphics are stored on the receiver, and displayed according to the forecast, which is selected by ZIP code or city according to user settings.
Additionally, starting in 2011, DirecTV users with digital video recorders will have commercials downloaded to their boxes, which will play according to their demographic information, likely commanding higher revenue from advertisers. This may eventually lead to or merge with interactive television, which may find more success on cable and telco television because of the lack of a return channel on satellite and broadcast. Internet-connected TVs may erode this barrier as well, however, with only their embedded flash memory chip necessary to hold short video clips.
The ATSC 3.0 standard, the newest standard planned for over-the-air television, has an emphasis on targeted news, weather or information to a ZIP code, along with advertising and overall improved tracking of viewers; the standard will likely require current sets to utilize a set-top box to receive ATSC 3.0 signals before the technology becomes commoditized into future sets.
References
See also
Broadcast automation and centralcasting
Emergency Alert System
Station identification
Broadcast engineering
Television terminology
Radio broadcasting | Local insertion | [
"Engineering"
] | 2,216 | [
"Broadcast engineering",
"Electronic engineering"
] |
9,634,634 | https://en.wikipedia.org/wiki/Mioara%20Mugur-Sch%C3%A4chter | Mioara Mugur-Schächter is a French-Romanian physicist specialized in fundamental quantum mechanics, probability theory, and theory of communication of information. She is also an epistemologist. As a professor at the University of Reims, she founded there the Laboratoire de Mécanique Quantique et Structures de l'Information, which she directed until 1997.
During an interview in 2015, Mugur-Schäcter explained how she worked on the invalidation of John von Neumann's no hidden variables proof during her PhD. Her academic advisor was Louis de Broglie.
References
Quantum physicists
Year of birth missing (living people)
Living people
Romanian emigrants to France
Academic staff of the University of Reims Champagne-Ardenne
French physicists | Mioara Mugur-Schächter | [
"Physics"
] | 157 | [
"Quantum physicists",
"Quantum mechanics"
] |
9,634,941 | https://en.wikipedia.org/wiki/Gene%20trapping | Gene trapping is a high-throughput approach that is used to introduce insertional mutations across an organism's genome.
Method
Trapping is performed with gene trap vectors whose principal element is a gene trapping cassette consisting of a promoterless reporter gene and/or selectable genetic marker, flanked by an upstream 3' splice site (splice acceptor; SA) and a downstream transcriptional termination sequence (polyadenylation sequence; polyA).
When inserted into an intron of an expressed gene, the gene trap cassette is transcribed from the endogenous promoter of that gene in the form of a fusion transcript in which the exon(s) upstream of the insertion site is spliced in frame to the reporter/selectable marker gene. Since transcription is terminated prematurely at the inserted polyadenylation site, the processed fusion transcript encodes a truncated and nonfunctional version of the cellular protein and the reporter/selectable marker. Thus, gene traps simultaneously inactivate and report the expression of the trapped gene at the insertion site, and provide a DNA tag (gene trap sequence tag, GTST) for the rapid identification of the disrupted gene.
Access
The International Gene Trap Consortium is centralizing the data and supplies modified cell lines.
References
Further reading
External links
Genetics | Gene trapping | [
"Biology"
] | 260 | [
"Genetics"
] |
9,635,291 | https://en.wikipedia.org/wiki/The%20Tragedy%20of%20Man | The Tragedy of Man () is a play written by the Hungarian author Imre Madách. It was first published in 1861. The play is considered to be one of the major works of Hungarian literature and is one of the most often staged Hungarian plays today. Many lines have become common quotations in Hungary. The 1984 film The Annunciation (Angyali üdvözlet) was based on the play, as was the 2011 animated film The Tragedy of Man.
Synopsis
The main characters are Adam, Eve and Lucifer. As God creates the universe, Lucifer decries it as futile, stating that man will soon aspire to be gods and demanding their own right of the world, because man was created to the image of God, "the ancient spirit of denial". God casts him out of Heaven, but grants his wish: the two cursed trees in Eden, the Tree of Knowledge and the Tree of Immortality. Playing on Eve's vanity and Adam's pride, Lucifer tempts both into sin. After the Fall and expulsion from Eden, Adam is still too proud to admit that he acted wrongly. Instead, he recounts his dreams of human progress and achievement; he feels that now, unencumbered by God's rules, he is ready to pursue his own glory. Lucifer puts Adam to sleep, and the two begin to travel through history. The first period they visit, ancient Egypt, is the realization of Adam's dream of immense human achievements. However, his joy is abruptly cut off when he finds that the pyramids are being built on the backs of slaves (as a later-executed slave points out, "millions for one"). Adam, in the role of a pharaoh, falls in love with Eve, a slave-girl; with renewed hope, he now tells Lucifer to take him to a world where all men live in equality, and Lucifer transports him to democratic Greece. In each period, Adam's previous dreams are exposed as futile, flawed, or unattainable, and Eve appears just in time to refresh Adam's spirit, and the cycle repeats.
Adam and Lucifer are introduced at the beginning of each scene, with Adam assuming various important historical roles and Lucifer usually acting as a servant or confidant. Eve enters only later in each scene, usually as a historical character. Adam is usually engrossed in his role at the beginning of each scene, and only becomes self-aware and aware of Lucifer as his guide near the end. Eve never breaks out of character. From the 19th century period on, Adam is no longer a leader, but retreats into an observer role, his political and historical enthusiasm having disappeared. Likewise, throughout the dream, Adam is older and older with each passing scene, representing not only his increasing wisdom but also the increasing burden of hopelessness.
The final dream scene is in an ice age in the far future. The Sun is dying, civilization has disappeared, and mankind has been reduced to a few scattered savages trying to eke out a living. It is never addressed whether this is truly the future Madách foresaw, or whether this is an elaborate illusion on the part of Lucifer to make Adam lose hope once and for all.
Awaking from his dream, Adam declares that the future is hopeless, and that the only course of action now open to him is to kill himself, thereby ending the human race before it begins and preventing all the meaningless suffering the future holds. As he is poised to throw himself from a cliff, Eve finds him, and happily announces that she is pregnant. Adam falls to his knees and declares that God has vanquished him. God rebukes Satan, and tells Adam that regardless of whether he sees hope or not, his task is only to "strive on, and have faith."
Sequence of scenes
The Tragedy of Man contains fifteen scenes, with ten historical periods represented. The scenes, their locations, and the identity of the main protagonists in each are as follows.
SCENE 1 – In Heaven, immediately following the creation.
SCENE 2 – In the Garden of Eden at the Beginning of Human History, likely around 75,000 BC.
SCENE 3 – Outside the Garden of Eden at the Beginning of Human History.
SCENE 4 – Egypt, c. 2686-2648 BC. Adam is a Pharaoh, most likely Djoser; Lucifer his Vizier Imhotep; Eve is the widow of a slave.
SCENE 5 – Athens, 490-489 BC. Adam is Miltiades the Younger; Lucifer is a city guard; Eve is Miltiades's wife.
SCENE 6 – Rome, c. 67 AD. Adam is a wealthy Roman; Lucifer is his friend, Eve is a prostitute.
SCENE 7 – Constantinople, 1096-1099 AD. Adam is Tancred, Prince of Galilee; Lucifer is his squire; Eve is a noble maiden forced to become a nun.
SCENE 8 – Prague, c. 1608. Adam is Johannes Kepler; Lucifer is his pupil; Eve is his wife, Barbara.
SCENE 9 – Paris, 1793-1794 (in a dream of Kepler). Adam is Georges Danton; Lucifer is an executioner; Eve appears in two forms, first as an aristocrat about to be executed, then immediately following as a bloodthirsty poor woman.
SCENE 10 – Prague, c. 1612. Adam is Johannes Kepler; Lucifer is his pupil; Eve is his wife, Barbara.
SCENE 11 – London, 19th century. Adam and Lucifer are nameless Englishmen; Eve is a young woman of the middle class.
SCENE 12 – A utopist socialist Phalanstery, in the future (most likely in 2000 AD). Adam and Lucifer masquerade as traveling chemists; Eve is a worker who protests when she is separated from her child.
SCENE 13 – Space. Adam and Lucifer are themselves, Eve does not appear in this scene.
SCENE 14 – An ice age in the distant future, at least 6000 AD. Adam is a broken old man; Lucifer is himself; Eve is an Eskimo's wife.
SCENE 15 – Outside Eden at the Beginning of Human History.
Interpretation
The play is invariably compared to John Milton's Paradise Lost, as the two deal with the same subject matter—the creation and fall of Man, and the devil's role in it. As in Paradise Lost, some critics maintain that the true protagonist of the Tragedy is Lucifer himself, being more active than Adam and God combined. Milton offers a more well-rounded Lucifer, however; he is motivated chiefly by a desire for power, and all his actions stem from that, rather than from any specifically malicious drive. Madách's version is significantly more one-sidedly villainous, seeking to destroy mankind simply to prove God's creation experiment a failure. This spite, combined with his charisma in dealing with Adam and Eve, make him a decidedly sinister character, more so than Milton's.
Some critics suggest that the unique portrayal of Eve, the first woman, was prompted by Madách's own unhappy marriage. Eve is both the vehicle of Adam's fall, offering him the apple, but through her appearance in each scene, is also usually the means by which Adam regains his hope for the future. In the end, she is the force which prevents his demise. The relationship between man and woman is indeed at the heart of the play, portrayed as being both deeply flawed on the one hand, yet still affirmed as the basic human relationship.
While these interpretations may be up for discussion, the role of Hegelian dialectic in the sequencing of scenes is an established fact. Each scene, each historical period, is the realization of some ideal of Adam (thesis), which Lucifer then exposes as being deeply flawed (antithesis). Adam, on the verge of losing hope, comes into contact with Eve, and decides upon a new ideal (synthesis) which would cure the worst problems of his present reality. The cycle then repeats. But each time Lucifer shows an age to Adam, he deceives Adam: Lucifer always shows the age not when the new ideal was ascending and contributed to the well-being of the human race. Instead, Lucifer and Adam experience the declining phase of the ages. Thus, contrary to Hegel's philosophy, what Adam sees is that humanity does not constantly build towards a glorious future, but is slowly sinking into worse and worse depravity.
This leads to the most famous and one of the most controversial elements of the play. Adam cannot understand what the purpose of his existence is if mankind's future is so bleak. The last line is spoken by God: "Mondottam, ember, küzdj és bízva bízzál!" ("I have told you, Man: strive on, and trust!") Depending on the interpretation, this can either be seen cynically as the words of a capricious deity, or else pointing to a "hope beyond all hope," that God has a purpose for all things which man may not necessarily comprehend. This is markedly different from Paradise Lost, where the Christian hope is explicitly spelled out.
It may therefore be tempting to suggest that The Tragedy of Man is not really a Christian play. It is, in fact, rather critical of historical Christianity. However, it is really only the institutional Roman Catholic Church that comes under direct attack. His brief portrayal of the early church, and St. Peter specifically, is also completely positive. It is certain that Madách's contemporaries likewise saw the play as unquestionably Christian in character. János Arany, who proofread Madách's poetry, was at first so disgusted by Lucifer's apparent blasphemous behaviour in the first scene that he refused to read further; however, once Madách begged him to read it to the end, he felt that the rest of the play's Christianity justified and explained what he had at first misinterpreted. Therefore, the interpretation of God as a capricious and arbitrary deity who wants to see his creations toil and suffer for no purpose does not seem to fit with Madách's probable intentions.
Literary influence, notably from Milton's Paradise Lost and Goethe's Faust, cannot be overlooked. Both notably contributed to the representation of the Lucifer, that takes characteristics from both Milton's Satan and Goethe's Mephistopheles. Likewise, existentialist themes reflecting on the apparent absurdity of existence are present throughout; Kierkegaard's influence can also be inferred, especially in the ending, which affirms both the world's meaninglessness and the meaningfulness of striving for God.
Adaptations
Stage
The poem is quite suitable for the stage, but a bit lengthy. German, Czech and Polish theaters have staged adaptations.
Opera
There are also two operas based on the play: a two-act mystery opera ("Az ember tragédiája") by the Hungarian composer György Ránki and a very large-scale work by the English composer Clive Strutt ("The Tragedy of Man").
Animation
Marcell Jankovics directed the animated film The Tragedy of Man, produced from 1988 to 2011 at Pannonia Film Studio. Some of the segments were showcased individually over the years, and the finished 160-minute feature film was finally released in 2011.
Cinema
Directed by András Jeles, Angyali üdvözlet (The Annunciation) was released in 1984, in which children play all the characters.
References
External links
Az ember tragédiája
Translations:
The Tragedy of Man (translation by George Szirtes)
The Tragedy of Man (translation by J. C. W. Horne)
The Tragedy of Man (translation by Iain Macleod)
Tragedy of the Man (translation by Ottó Tomschey)
The Tragedy of Man (translation by )
Illustrations:
Mihály Zichy's Illustrations of The Tragedy of Man
Illustrations of the Tragedy by famous Hungarian artists
Adaptations:
Plays by Imre Madách
1861 plays
Cultural depictions of Adam and Eve
Cultural depictions of Georges Danton
Cultural depictions of Johannes Kepler
Fiction about God
Plays about slavery
Plays set in ancient Greece
Plays set in Athens
Plays set in antiquity
Plays set in Egypt
Plays set in Paris
Plays set in Germany
Plays set in the 11th century
Plays set in the 1790s
Fiction about the Devil
Lucifer
Plays set in the 17th century
Plays set in the 19th century
Works set in the future
Plays set in Prague
Plays set in the 1600s
Fiction set in the 1610s | The Tragedy of Man | [
"Astronomy"
] | 2,560 | [
"Cultural depictions of astronomers",
"Cultural depictions of Johannes Kepler"
] |
9,635,691 | https://en.wikipedia.org/wiki/Davies%20attack | In cryptography, the Davies attack is a dedicated statistical cryptanalysis method for attacking the Data Encryption Standard (DES). The attack was originally created in 1987 by Donald Davies. In 1994, Eli Biham and Alex Biryukov made significant improvements to the technique. It is a known-plaintext attack based on the non-uniform distribution of the outputs of pairs of adjacent S-boxes. It works by collecting many known plaintext/ciphertext pairs and calculating the empirical distribution of certain characteristics. Bits of the key can be deduced given sufficiently many known plaintexts, leaving the remaining bits to be found through brute force. There are tradeoffs between the number of required plaintexts, the number of key bits found, and the probability of success; the attack can find 24 bits of the key with 252 known plaintexts and 53% success rate.
The Davies attack can be adapted to other Feistel ciphers besides DES. In 1998, Pornin developed techniques for analyzing and maximizing a cipher's resistance to this kind of cryptanalysis.
References
Cryptographic attacks
Data Encryption Standard | Davies attack | [
"Technology"
] | 224 | [
"Cryptographic attacks",
"Computer security exploits"
] |
9,636,455 | https://en.wikipedia.org/wiki/Logarithmic%20number%20system | A logarithmic number system (LNS) is an arithmetic system used for representing real numbers in computer and digital hardware, especially for digital signal processing.
Overview
A number, , is represented in an LNS by two components: the logarithm () of its absolute value (as a binary word usually in two's complement), and its sign bit ():
An LNS can be considered as a floating-point number with the significand being always equal to 1 and a non-integer exponent. This formulation simplifies the operations of multiplication, division, powers and roots, since they are reduced down to addition, subtraction, multiplication, and division, respectively.
On the other hand, the operations of addition and subtraction are more complicated and are calculated by the formulae
where the "sum" function is defined by , and the "difference" function by . These functions and are also known as Gaussian logarithms.
The simplification of multiplication, division, roots, and powers is counterbalanced by the cost of evaluating these functions for addition and subtraction. This added cost of evaluation may not be critical when using an LNS primarily for increasing the precision of floating-point math operations.
History
Logarithmic number systems have been independently invented and published at least three times as an alternative to fixed-point and floating-point number systems.
Nicholas Kingsbury and Peter Rayner introduced "logarithmic arithmetic" for digital signal processing (DSP) in 1971.
A similar LNS named "signed logarithmic number system" (SLNS) was described in 1975 by Earl Swartzlander and Aristides Alexopoulos; rather than use two's complement notation for the logarithms, they offset them (scale the numbers being represented) to avoid negative logs.
Samuel Lee and Albert Edgar described a similar system, which they called the "Focus" number system, in 1977.
The mathematical foundations for addition and subtraction in an LNS trace back to Zecchini Leonelli and Carl Friedrich Gauss in the early 1800s.
Applications
In the late 1800s, the Spanish engineer Leonardo Torres Quevedo conceived a series of analogue calculating mechanical machines and developed one that could solve algebraic equations with eight terms, finding the roots, including the complex ones. One part of this machine called an "endless spindle" allowed the mechanical expression of the relation , with the aim of extracting the logarithm of a sum as a sum of logarithms.
A LNS has been used in the Gravity Pipe (GRAPE-5) special-purpose supercomputer that won the Gordon Bell Prize in 1999.
A substantial effort to explore the applicability of LNSs as a viable alternative to floating point for general-purpose processing of single-precision real numbers is described in the context of the European Logarithmic Microprocessor (ELM). A fabricated prototype of the processor, which has a 32-bit cotransformation-based LNS arithmetic logic unit (ALU), demonstrated LNSs as a "more accurate alternative to floating-point", with improved speed. Further improvement of the LNS design based on the ELM architecture has shown its capability to offer significantly higher speed and accuracy than floating-point as well.
LNSs are sometimes used in FPGA-based applications where most arithmetic operations are multiplication or division.
See also
Decibel
Subnormal number
Tapered floating point (TFP)
Level-index arithmetic (LI) and symmetric level-index arithmetic (SLI)
Gaussian logarithm
Zech's logarithm
ITU-T G.711
A-law algorithm
μ-law algorithm
References
Further reading
Previously published in:
(NB. Describes a 13-bit LNS used in Yamaha music synthesizers during the 1980s.)
. Also reprinted in:
(389 pages)
External links
A site that lists LNS papers
esprit – European Logarithmic Microprocessor (formerly the 'High Speed Logarithmic Arithmetic' (HSLA) project)
A VHDL library for LNS hardware generation
A Short Account on Leonardo Torres’ Endless Spindle
Computer arithmetic
Digital signal processing
Logarithms | Logarithmic number system | [
"Mathematics"
] | 877 | [
"Logarithms",
"Computer arithmetic",
"Arithmetic",
"E (mathematical constant)"
] |
9,636,501 | https://en.wikipedia.org/wiki/Crescendo%20pedal | A crescendo pedal is a large pedal commonly found on medium-sized and larger pipe organs (as well as digital organs), either partially or fully recessed within the organ console. The crescendo pedal incrementally activates stops as it is pressed forward and removes stops as it is depressed backward. The addition of stops, in order from quietest to loudest, creates the effect of a crescendo (and, likewise, a diminuendo, when the stops are deactivated). In actual use, the operation of the crescendo pedal usually does not move the draw knobs or stop tabs on the console; the stops are electronically activated inside the organ. Often an indicator light or lights will be present on the console to inform the organist of when the crescendo pedal is activated and how far it is engaged. The crescendo pedal is located directly above the pedalboard, to the right of any expression pedals that may be present.
The earliest type of automatic crescendo device was the Rollschweller (German for "roll-sweller") or Walze (German for "roller"), seen in large Romantic music era organs of the nineteenth century, almost exclusively in Germany. It consists of a wheel and axle, which would be horizontally mounted directly above the pedalboard. When turned toward the organist, the wheel would activate a mechanism that would add stops to the registration. Likewise, turning the wheel back would remove stops. The Rollschweller is constructed so that it may be turned forward or backward indefinitely. This gives the device a much longer field of operation than the modern crescendo pedal, thus making the dynamic change more smooth and gradual. It is especially helpful and appropriate in the playing of the organ works of Max Reger, Franz Liszt, and Sigfrid Karg-Elert, who all wrote for organs that featured a Rollschweller.
As the use of electricity became widespread in the early twentieth century, organ builders began to apply it to their instruments, electrifying the key action and the stop action as well as the expression pedals. An electrically operated crescendo pedal resembling an expression pedal was invented and mounted to the right of the expression pedals. The order in which the stops were activated by the crescendo pedal was set by the organ builder and could not be modified by the organist. This was the case until the later part of the twentieth century, when computerized devices were incorporated into console design, allowing greater customization of registration through more sophisticated combination actions. As a result, in organs with these devices, the stops controlled by the crescendo pedal are usually customizable, as is the order in which they are activated.
Reed organs and harmoniums of the late 19th and early 20th centuries often had a similar mechanism to a crescendo pedal. Since the player's feet were needed to pedal the bellows that provided the wind for the instrument, the mechanism was operated by a 'paddle' lever moved by one of the player's knees (the paddle being located under the keyboard). Usually this was called a 'full organ pedal', as it did not gradually engage ranks of stops in the manner of a true crescendo pedal, but simply engaged all the stops (and usually any octave couplers fitted to the instrument) when operated, with no progressive action.
Use of the crescendo pedal
The crescendo pedal is typically used only in certain repertoire, and, generally speaking, the organ's expression pedal(s) are more commonly used. Because the crescendo pedal both resembles and is adjacent to the expression pedal(s), it may confuse beginning organists, such as pianists who are filling in at the church organ, who intend to use the expression pedal(s) rather than the crescendo pedal. To avoid this danger, the organist should look at the pedals before playing to ascertain if they are labeled, as well as practice locating the correct pedal by feel. When feeling for a pedal while playing, the organist should remember that the crescendo pedal is normally the right-most of the volume pedals, and that its surface is often raised slightly above the expression pedal(s) so as to help the organist to avoid selecting it by mistake.
References
Pipe organ components | Crescendo pedal | [
"Technology"
] | 903 | [
"Pipe organ components",
"Components"
] |
9,636,856 | https://en.wikipedia.org/wiki/Mansion%20stage | A mansion stage is a stage for theatrical performances. They originated in churches where they were small wooden platforms with supports and a roof. Mansions were stage structures used in medieval theatre to represent specific locations, such as Heaven or Hell. The actors would move between these mansions as the play demanded. The acting area of the stage was called the platea, and mansions were placed around the platea. As the actors moved between the mansions, the platea would take on the scenic identity of each mansion. In England, pageant wagons were used for the cycle dramas to hold the mansion, the plateau, and a dressing area. These were used to move the scene from one audience to the next, unlike in the church where the mansions were stationary and both the performer and the congregation would move from mansion to mansion.
Sociohistorical context
After the fall of the Roman Empire, structured drama became practically nonexistent. Theatrical performances persisted in some small degree through local and travelling troupes of what would later be called minstrels. These minstrels, along with the monastery scholars, would carry the knowledge and tradition of the Roman Theatre until the revival of theatre in the Early Middle Ages, beginning around 500 C.E. As the church’s power grew, they attempted to absorb the pagan religions. In order to draw people in, while allowing them to keep a sense of their traditions, they superimposed Christian theology on pagan holiday celebrations. Easter was already the appropriate time of year to take the place of the spring fertility festivals. The Roman festivals celebrating the births of Dionysus, Osiris, and other lesser deities became Christmas, despite Christ's birth never being celebrated in the winter before.
To keep up with the elaborate and theatrical celebrations found in the pagan religions, the church began creating spectacle performances. For example, they might place a cross wrapped in burial clothes in a tomb on Good Friday and raise it on Sunday, or stage elaborate mystery plays such as the one that lasted multiple days in the town of Mons, France. The processionals evolved into the liturgical dramas of the high Middle Ages. By 1300, the performance of liturgical dramas in churches was widespread across Western Europe, and so began the use of mansions and plateas, which persisted throughout the Middle Ages.
In the 14th century, the Church in England, in an attempt to continue to spark interest and devotion to the church, began to build movable mansions, called pageant wagons, to carry to different parts of town to create an elaborate travelling show. Carrying the performances out of the church, the play slowly became more secular. Audiences prized the comic characters such as lesser demons and drunks, and those who played them well, reigniting professionalism in performance. The use of mansions, and eventually pageant wagons helped to create an affirmation of faith in the church in the Middle Ages.
Specific characteristics of mansions
In the earliest days of liturgical drama, plays were performed inside the church with limited scenery and the focus of the audience on the action. Mansions were used to indicate location but much of the performance took place on the platea, the open space in front of the scenic structure, with the actors moving from mansion to mansion only when strictly necessary. The increase in length of the plays and the inclusion of a wider variety of locations that needed to be represented by individual mansions was part of what caused the movement of performances from clergy control inside church spaces (where the mansions were nestled within structural arches or alcoves) to laity control outdoors in the streets or public squares.
This movement to the outdoors resulted in two different methods of staging: in England, mansions were converted into pageant wagons, which could be wheeled along in a parade-like fashion from audience to audience, while in France and the rest of continental Europe, the stations were more commonly lined up in an open square, sometimes on a u-shaped or circular platform, and the actors would move from mansion to mansion. As time passed the plays came to be performed in the vernacular and required the involvement of community members, local guilds, and patronage from town government to produce the increasingly spectacular cycle, mystery, and morality plays.
Mansions, either stationary or moveable, represented a wide variety of locations such as the House of Adam, the Temple, the Garden of Gethsemane, and Mount Olivet, and were often lavishly decorated to add to the spectacle of the performance. In the mystery play at Mons, France in 1501, five painters were hired to paint the 67 mansion stages with various pigments as well as varnish, gold leaf, and silver powder. They were also responsible for painting the backdrops, the furniture and other set pieces, and imitation draperies. It is likely that because of the limited amount of total stage space, many of the mansion stages doubled for one another or were changed in between scenes. Flying machines, trapdoors, rope-and-pulley systems, and special effects such as a dragon that spit fire, light shining from the manger in the Nativity and torrential rain for the creation of the world were popular. Machinery or hidden sections such as Heaven would often be concealed with drapery or painted clouds, as was done in the Mons production.
A great number of people were employed in the production of these mansions, from Jehan de Dours, cabinetmaker, paid 48 sols for “making castles and turrets”, to Pierart Viscave, tinker, for installing sheets of metal to be used to create thunder effects, to Jehan du Fayt and seventeen assistants for working as stage hands for the nine-day performance. Both the production period and the performance of the outdoor vernacular medieval drama were extensive, with the 22 mansions for a production in Rouen prepared over 18 years. These medieval spectacles laid the foundation for the flourishing of drama in the Renaissance of later centuries.
See also
Liturgical drama
Medieval architecture
Medieval guilds
Scenic design
External links
Overview of medieval drama
E-book of history of scenic art
History of Western theatre from the Encyclopædia Britannica
Integrated Performing Arts Guild page on medieval theatre
Overview of different forms of medieval theatrical literature
References
History of theatre
Medieval drama
Scenic design | Mansion stage | [
"Engineering"
] | 1,246 | [
"Scenic design",
"Design"
] |
9,638,061 | https://en.wikipedia.org/wiki/Humberto%20Maturana | Humberto Maturana Romesín (September 14, 1928 – May 6, 2021) was a Chilean biologist and philosopher. Many consider him a member of a group of second-order cybernetics theoreticians such as Heinz von Foerster, Gordon Pask, Herbert Brün and Ernst von Glasersfeld, but in fact he was a biologist, scientist.
Maturana, along with Francisco Varela and Ricardo B. Uribe, was known for creating the term "autopoiesis" about the self-generating, self-maintaining structure in living systems, and concepts such as structural determinism and structural coupling. His work was influential in many fields, mainly the field of systems thinking and cybernetics. Overall, his work is concerned with the biology of cognition. Maturana (2002) insisted that autopoiesis exists only in the molecular domain, and he did not agree with the extension into sociology and other fields:
The molecular domain is the only domain of entities that through their interactions give rise to an open ended diversity of entities (with different dynamic architectures) of the same kind in a dynamic that can give rise to an open ended diversity of recursive processes that in their turn give rise to the composition of an open ended diversity of singular dynamic entities.
Life and career
Maturana was born in Santiago, Chile. After completing secondary school at the Liceo Manuel de Salas in 1947, he enrolled at the University of Chile, studying first medicine in Santiago, then biology in London and Cambridge, Mass.
Anatomy and physiology
In 1954, he obtained a scholarship from the Rockefeller Foundation to study anatomy and neurophysiology with J. Z. Young (the “discoverer” of the squid giant axon and who later wrote the foreword to The Tree of Knowledge) at University College London. Maturana wrote that he was as an ”invisible” student never officially accepted in University College, London. Nonetheless, he did research and produced a paper(1) investigating the possibility of the presence of efferent fibers running from the brain to the retina. In this study, he unilaterally severed optic nerves of toads who were maintained weeks to months post-surgery. Maturana then examined the ocular and brain stumps of the cut nerves using the conventional Weigert’s and Holmes’s nerve fiber staining methods and although 'thin', concluded that efferent fibers existed. Amphibians, unlike avian and reptile species, lacked a distinct isthmo-optic nucleus located in the caudal part of the midbrain with direct connections to the retina.
Maturana then went to Harvard for his PhD work with George B Chapman as his advisor. Chapman’s speciality was cell biology and ultrastructure. Maturana produced a PhD thesis in 1958 and a research paper(2) on the amphibian optic nerve. Why he did this particular work is not clear? Chapman was a cytologist using ultrastructural methods. He never worked on frogs or optic nerves even during his later distinguished career at Georgetown University. However, at MIT, down the street from Harvard, Jerome Lettvin was electrophysiologically recording from the frog optic nerve. Maturana made contact with Lettvin through J.Z. Young (who knew Lettvin and colleagues from work they carried out at the Zoological Station in Naples, Italy). Maturana's thesis revealed the frog optic nerve contains thirty times more fibers than previously estimated (3). Most of the fibers are unmyelinated and collectively the number of optic nerve fibers is around 500,000. He found that the number of fibers in the optic nerve approximately matches the number of ganglion cells in the retina.
Maturana formally joined Lettvin’s laboratory at MIT’s Research Laboratory of Electronics (RLE) as a post-doctoral fellow. The details from his thesis about the frog optic nerve were useful for subsequent physiological studies. Maturana and Lettvin recorded electrical activity in the frog optic nerve and in the midbrain optic tectum, the principal target of the retina. They found that the unmyelinated optic nerve fibers terminate in the most superficial layers of the tectum and the myelinated optic nerve fibers terminate in layers below. Several sets of optic nerve fibers form visuotopic maps of visual space in the tectum. They published the paper "What the Frog's Eye Tells the Frog's Brain" (4) with Warren McCulloch and Walter Pitts, also at MIT, that became extensively cited and may have been one of the earliest papers in the realm of neuroethology.
Their work was distinguished from other similar studies at the time by using “natural” visual stimuli rather than spots of light of various sizes and durations. They discovered five physiological types of retinal ganglion cells. Four of these five types are restricted to an individual layer of the tectum. One of these types is insensitive to spots of light but are exquisitely sensitive to small, dark, convexly-shaped moving objects that they dubbed "bug detectors". Lettvin and Maturana carried out the physiological and anatomical experiments and McCulloch and Pitts, famed for earlier theoretical work modeling neurons and neural networks and for epistemological approaches to the recognition of universals, provided theoretical rigor.
Maturana as first author, co-wrote a longer paper elaborating on the results of the Frog’s Eye paper(5) The MIT group also produced a brief but notable physiological paper on regeneration of cut frog optic nerve fibers and showed they grow back to their original tectal locations(6). They also produced a paper describing two classes of visually evoked tectal cells. One class responded primarily to novel visual stimuli (“newness” cells); the other class responded best to stimuli repeatedly presented (“sameness” cells)(7).
Maturana followed his anuran studies with studies in pigeon vision(8, 9) and with Lettvin and Wall, one of the first electrophysiological studies in octopus(10). After a 2 year post-doctoral period at MIT, he returned to Chile in 1960.
Academic career
Maturana was appointed Assistant Prof in Dept of Biology of Medical School of University of Chile Santiago, at the age of 32. He worked in neuroscience at the University of Chile, in the Biología del Conocer (Biology of Knowing) research center. Maturana's work has been developed and integrated into the work on ontological coaching developed by Fernando Flores and Julio Olalla.
In 1994, he received Chile's National Prize for Natural Sciences.
Maturana established his own reflection and research center, the Instituto de Formación Matriztica. In 2020, he was awarded an honorary fellowship by the Cybernetics Society.
Maturana died in Santiago on May 6, 2021, at age 92, due to pneumonia.
Work
Maturana's research interests concern concepts like cognition, autopoiesis, languaging, zero time cybernetics and structurally determined systems. Maturana's work extends to philosophy, cognitive science and even family therapy. He was inspired by the work of the biologist Jakob von Uexküll.
His inspiration for his work in cognition came while he was a medical student and became seriously ill with tuberculosis. Confined in a sanatorium with very little to read, he spent time reflecting on his condition and the nature of life. What he came to realize was "that what was peculiar to living systems was that they were discrete autonomous entities such that all the processes that they lived, they lived in reference to themselves ... whether a dog bites me or doesn't bite me, it is doing something that has to do with itself." This paradigm of autonomy formed the basis of his studies and work.
Maturana and his student Francisco Varela were the first to define and employ the concept of "autopoiesis", which was Maturana's original idea. Aside from making important contributions to the field of evolution, Maturana is associated with an epistemology built upon empirical findings in neurobiology. Maturana and Varela wrote "Living systems are cognitive systems, and living as a process is a process of cognition. This statement is valid for all organisms, with or without a nervous system."
Reflections on life and association with Francisco Varela
In an article in Constructivist Foundations. Maturana described the origins of the concept of autopoiesis and his collaboration with Varela.
Publications
Articles on anatomy and physiology
1958 H.R. Maturana Efferent fibres in the optic nerve of the toad (Bufo bufo) J. Anat Jan 92 : 21-27. [ He thanked JZ Young “for always valuable criticism and friendly encouragement.” On the paper his institutional address is Dept. Anatomy University College, London. With present address Biological Laboratory, Harvard University, Cambridge Mass.]
1959 Humberto R Maturana The Fine Anatomy of the optic nerve of anurans – an electron microscope study. Journal of Biophysical and Biochemical Cytology 7 107-120 [Present address: Research Laboratory of Electronics, MIT “My appreciation to Professor G.B. Chapman under whom this work was done as a doctoral thesis”]
1959 Maturana, H.R. Number of Fibres in the Optic Nerve and the number of Ganglion Cells in the Retina of Anurans Nature 183 1400-1407.
1959 J.Y. Lettvin, H.R. Maturana, W. S. McCulloch. W.H. Pitts What the Frog’s Eye Tells The Frog’s Brain Proceedings of the IRE 47: 1940-1951.
1960 H.R. Maturana, J.Y. Lettvin, W. S. McCulloch. W.H. Pitts Anatomy and Physiology of Vision in the frog (Rana pipiens). J. General Physiology 43 129-175.
1959 H.R. Maturana, J.Y. Lettvin, W. S. McCulloch. W.H. Pitts Evidence that cut optic nerve fibers grow back to original location. Science 130: 1709-10.
1960 J. Y. Lettvin, H. R. Maturana, W. H. Pitts, W. S. McCulloch Two Remarks on the Visual System of the Frog [In MIT Press publication, 'Sensory Communications'].
1963 H.R. Maturana and S. Frenk Directional movement and horizontal edge detectors in the pigeon retina Science 142 977-979.
1965 H,R. Maturana and S. Frenk Synaptic connections of the centrifugal fibers in the pigeon retina. Science 150 359-361 1965.
1965 Boycott BB, Lettvin JY, Maturana HR, Wall PD Octopus optic responses Experimental Neurology, 12, 247-256.
1968 Maturana, H, G. Uribe, S. Frenk A biological theory of relativistic colour coding in the primate retina Arch Biol Med Exp. 1:1-30
1970 Varela, FG, Maturana, HR Time courses of excitation and inhibition in retinal ganglion cells. Experimental Neurology
1970 H.R. Maturana, F. Varela and S. Frenk Size Constancy and the Perception of Space Cognition I (I), pp. 97-104. 1972
Philosophy
The initial paper which stands as a prelude to all that followed:
Biology of Cognition . Humberto R. Maturana. Biological Computer Laboratory Research Report BCL 9.0. Urbana IL: University of Illinois, 1970. As Reprinted in: Autopoiesis and Cognition: The Realization of the Living. Dordecht: D. Reidel Publishing Co., 1980, pp. 5–58.
Books
1979 Autopoiesis and Cognition: The Realization of the Living With Francisco Varela. (Boston Studies in the Philosophy of Science). ISBN 90-277-1015-5.
1984 The tree of knowledge. Biological basis of human understanding. With Francisco Varela Revised edition (92) The Tree of Knowledge: Biological Roots of Human Understanding.
1990 Biology of Cognition and epistemology. Ed Universidad de la Frontera. Temuco, Chile.
1992 Conversations with Humberto Maturana: Questions to biologist Psychotherapist. With K. Ludewig. Ed Universidad de la Frontera. Temuco, Chile. 1992.
1994 Reflections and Conversations. With Kurt Ludewig. Collection Family Institute. FUPALI Ed. Cordova. 1994
1994 Democracy is a Work of Art. Collection Roundtable. Linotype Ed Bogota Bolivar y Cia.
1997 Objectivity - An argument to force. Santiago de Chile: Ed Dolmen.
1997 Machines and living things. Autopoiese to do Organização Vivo. With Francisco Varela Porto Alegre: Medical Arts, 1997.
2004 From Being to Doing, The Origins of the Biology of Cognition. With Bernhard Poerksen. Paperback, 2004
2009 The Origins of humanness in the Biology of Love. With Gerda Verden-Zoller and Pille Bunnell.
2004 From biology to psychology. Paperback.
2009 Sense of humanity. Paperback.
2008 Habitar humano en seis ensayos de biología-cultural. With Ximena Dávila.
2012 The Origin of Humanness in the Biology of Love. With Gerda Verden-Zöller. Edited by Pille Bunnell. Philosophy Document Center, Charlottesville VA; Exeter UK: Imprint Academic, Imprint Academic.
2015 El árbol del vivir. With Ximena Dávila.
2019 Historia de nuestro vivir cotidiano. With Ximena Dávila.
See also
Autopoiesis
Constructivism
Ernst von Glasersfeld
Francisco Varela
Heinz von Foerster
Molecular cellular cognition
Neurobiology
Neurophilosophy
Second-order cybernetics
Santiago theory of cognition
Vittorio Guidano
William Ross Ashby
References
Further reading
External links
Cultural Biology Certification - Brazil
Biology of Cognition Lab website
Appreciation of Maturana's work and philosophy (in Spanish with English subtitles)
1928 births
2021 deaths
20th-century Chilean non-fiction writers
20th-century Chilean male writers
21st-century Chilean non-fiction writers
21st-century Chilean male writers
20th-century Chilean philosophers
21st-century philosophers
20th-century Chilean biologists
Chilean scientists
Consciousness researchers and theorists
Cyberneticists
Systems biologists
Systems psychologists
Theoretical biologists
University of Chile alumni
Harvard University alumni
Alumni of University College London
Scientists from Santiago, Chile
Academics from Santiago, Chile
Members of the Chilean Academy of Sciences
Deaths from pneumonia in Chile
Chilean non-fiction writers | Humberto Maturana | [
"Biology"
] | 3,071 | [
"Bioinformatics",
"Theoretical biologists"
] |
9,638,111 | https://en.wikipedia.org/wiki/Raether%20limit | The Raether limit is the physical limiting value of the multiplication factor () or gas gain in an ionization avalanche process (Townsend avalanche).
Even though, theoretically, it seems as if can increase without limit (exponentially), physically, it is limited to about or (where is the first Townsend coefficient and is the length of the path of ionization, starting from the point of the primary ionization).
Heinz Raether postulated that this was due to the effect of the space charge on the electric field.
The multiplication factor or gas gain is of fundamental importance for the operation of the proportional counter and Geiger counter ionizing radiation detectors.
Sources
The Mechanism of the Electric Spark, Leonard Benedict Loeb, John M. Meek. Stanford University Press, 1941
High Voltage Engineering, M S Naidu, V Kamarju. Tata McGraw-Hill Education, 2009
Particle detectors
Ionization
Electrical phenomena | Raether limit | [
"Physics",
"Chemistry",
"Technology",
"Engineering"
] | 184 | [
"Ionization",
"Physical phenomena",
"Particle detectors",
"Measuring instruments",
"Electrical phenomena"
] |
9,638,200 | https://en.wikipedia.org/wiki/Boltzmann%20brain | The Boltzmann brain thought experiment suggests that it might be more likely for a brain to spontaneously form in space, complete with a memory of having existed in our universe, rather than for the entire universe to come about in the manner cosmologists think it actually did. Physicists use the Boltzmann brain thought experiment as a reductio ad absurdum argument for evaluating competing scientific theories.
In contrast to brain in a vat thought experiments, which are about perception and thought, Boltzmann brains are used in cosmology to test our assumptions about thermodynamics and the development of the universe. Over a sufficiently long time, random fluctuations could cause particles to spontaneously form literally any structure of any degree of complexity, including a functioning human brain. The scenario initially involved only a single brain with false memories, but physicist Sean M. Carroll pointed out that, in a fluctuating universe, the scenario works just as well with entire bodies and entire galaxies.
The idea is named after the physicist Ludwig Boltzmann (1844–1906), who, in 1896, published a theory that tried to account for the fact that the universe is not as chaotic as the budding field of thermodynamics seemed to predict. He offered several explanations, one of them being that the universe, even after it had progressed to its most likely spread-out and featureless state of thermal equilibrium, would spontaneously fluctuate to a more ordered (or low-entropy) state such as the universe in which we find ourselves. Boltzmann brains were first proposed as a reductio ad absurdum response to this explanation by Boltzmann for the low-entropy state of our universe.
The Boltzmann brain gained new relevance around 2002, when some cosmologists started to become concerned that, in many theories about the universe, human brains are vastly more likely to arise from random fluctuations; this leads to the conclusion that, statistically, humans are likely to be wrong about their memories of the past and in fact are Boltzmann brains. When applied to more recent theories about the multiverse, Boltzmann brain arguments are part of the unsolved measure problem of cosmology.
"Boltzmann universe"
In 1896, the mathematician Ernst Zermelo advanced a theory that the second law of thermodynamics was absolute rather than statistical. Zermelo bolstered his theory by pointing out that the Poincaré recurrence theorem shows statistical entropy in a closed system must eventually be a periodic function; therefore, the Second Law, which is always observed to increase entropy, is unlikely to be statistical. To counter Zermelo's argument, Boltzmann advanced two theories. The first theory, now believed to be the correct one, is that the universe started for some unknown reason in a low-entropy state. The second and alternative theory, published in 1896 but attributed in 1895 to Boltzmann's assistant Ignaz Schütz, is the "Boltzmann universe" scenario. In this scenario, the universe spends the vast majority of eternity in a featureless state of heat death; however, over enough eons, eventually a very rare thermal fluctuation will occur where atoms bounce off each other in exactly such a way as to form a substructure equivalent to our entire observable universe. Boltzmann argues that, while most of the universe is featureless, humans do not see those regions because they are devoid of intelligent life; to Boltzmann, it is unremarkable that humanity views solely the interior of its Boltzmann universe, as that is the only place where intelligent life lives. (This may be the first use in modern science of the anthropic principle).
In 1931, astronomer Arthur Eddington pointed out that, because a large fluctuation is exponentially less probable than a small fluctuation, observers in Boltzmann universes will be vastly outnumbered by observers in smaller fluctuations. Physicist Richard Feynman published a similar counterargument within his widely read Feynman Lectures on Physics. By 2004, physicists had pushed Eddington's observation to its logical conclusion: the most numerous observers in an eternity of thermal fluctuations would be minimal "Boltzmann brains" popping up in an otherwise featureless universe.
Spontaneous formation
In the universe's eventual state of ergodic "heat death", given enough time, every possible structure (including every possible brain) will presumably get formed via random fluctuation, the timescale of which is related to the Poincaré recurrence time. A Boltzmann brain (or body or world) need not fluctuate suddenly into existence, argue Anthony Aguirre, Sean M. Carroll, and Matthew C. Johnson. Rather, it would form in a sequence of smaller fluctuations that would look like the brain's decay path run in reverse. Boltzmann-style thought experiments generally focus on structures like human brains that are presumably self-aware observers. However, smaller structures that minimally meet the criteria are vastly and exponentially more common than larger structures; a rough analogy is how the odds of a single real English word showing up when one shakes a box of Scrabble letters are greater than the odds that a whole English sentence or paragraph will form. The average timescale required for the formation of a Boltzmann brain is vastly greater than the current age of the universe. In modern physics, Boltzmann brains can be formed either by quantum fluctuation, or by a thermal fluctuation generally involving nucleation.
Via quantum fluctuation
By one calculation, a Boltzmann brain would appear as a quantum fluctuation in the vacuum after a time interval of years. This fluctuation can occur even in a true Minkowski vacuum (a flat spacetime vacuum lacking vacuum energy). Quantum mechanics heavily favors smaller fluctuations that "borrow" the least amount of energy from the vacuum. Typically, a quantum Boltzmann brain would suddenly appear from the vacuum (alongside an equivalent amount of virtual antimatter), remain only long enough to have a single coherent thought or observation, and then disappear into the vacuum as suddenly as it appeared. Such a brain is completely self-contained, and can never radiate energy out to infinity.
Via nucleation
Current evidence suggests that the vacuum permeating the observable universe is not a Minkowski space, but rather a de Sitter space with a positive cosmological constant. In a de Sitter vacuum (but not in a Minkowski vacuum), a Boltzmann brain can form via nucleation of non-virtual particles gradually assembled by chance from the Hawking radiation emitted from the de Sitter space's bounded cosmological horizon. One estimate for the average time required until nucleation is around years. A typical nucleated Boltzmann brain will cool off to absolute zero and eventually completely decay, as any isolated object would in the vacuum of space. Unlike the quantum fluctuation case, the Boltzmann brain will radiate energy out to infinity. In nucleation, the most common fluctuations are as close to thermal equilibrium overall as possible given whatever arbitrary criteria are provided for labeling a fluctuation a "Boltzmann brain".
Theoretically a Boltzmann brain can also form, albeit again with a tiny probability, at any time during the matter-dominated early universe.
Modern reactions to the Boltzmann brain problem
The consensus amongst cosmologists is that some yet-to-be-revealed error is hinted at by the surprising calculation that Boltzmann brains should vastly outnumber normal human brains. Sean Carroll states "We're not arguing that Boltzmann Brains exist—we're trying to avoid them." Carroll has stated that the hypothesis of being a Boltzmann brain results in "cognitive instability". Because, he argues, it would take longer than the current age of the universe for a brain to form, and yet it thinks that it observes that it exists in a younger universe, and thus this shows that memories and reasoning processes would be untrustworthy if it were indeed a Boltzmann brain. Seth Lloyd has stated, "They fail the Monty Python test: Stop that! That's too silly!" A New Scientist journalist summarizes that "The starting point for our understanding of the universe and its behavior is that humans, not disembodied brains, are typical observers".
Some argue that brains produced via quantum fluctuation, and maybe even brains produced via nucleation in the de Sitter vacuum, do not count as observers. Quantum fluctuations are easier to exclude than nucleated brains, as quantum fluctuations can more easily be targeted by straightforward criteria (such as their lack of interaction with the environment at infinity).
Carroll believes that a better understanding of the measurement problem in quantum mechanics would show that some vacuum states have no dynamical evolution and cannot support nucleated brains, nor any other type of observer. Some cosmologists believe that a better understanding of the degrees of freedom in the quantum vacuum of holographic string theory can solve the Boltzmann brain problem.
American theoretical physicist and mathematician Brian Greene states: "I am confident that I am not a Boltzmann brain. However, we want our theories to similarly concur that we are not Boltzmann brains, but so far it has proved surprisingly difficult for them to do so".
In single-universe scenarios
In a single de Sitter universe with a cosmological constant, and starting from any finite spatial slice, the number of "normal" observers is finite and bounded by the heat death of the universe. If the universe lasts forever, the number of nucleated Boltzmann brains is, in most models, infinite; cosmologists such as Alan Guth worry that this would make it seem "infinitely unlikely for us to be normal brains". One caveat is that if the universe is a false vacuum that locally decays into a Minkowski or a Big Crunch-bound anti-de Sitter space in less than 20 billion years, then infinite Boltzmann nucleation is avoided. (If the average local false vacuum decay rate is over 20 billion years, Boltzmann brain nucleation is still infinite, as the universe increases in size faster than local vacuum collapses destroy the portions of the universe within the collapses' future light cones). Proposed hypothetical mechanisms to destroy the universe within that timeframe range from superheavy gravitinos to a heavier-than-observed top quark triggering "death by Higgs".
If no cosmological constant exists, and if the presently observed vacuum energy is from quintessence that will eventually completely dissipate, then infinite Boltzmann nucleation is also avoided.
In eternal inflation
One class of solutions to the Boltzmann brain problem makes use of differing approaches to the measure problem in cosmology: in infinite multiverse theories, the ratio of normal observers to Boltzmann brains depends on how infinite limits are taken. Measures might be chosen to avoid appreciable fractions of Boltzmann brains. Unlike the single-universe case, one challenge in finding a global solution in eternal inflation is that all possible string landscapes must be summed over; in some measures, having even a small fraction of universes permeated with Boltzmann brains causes the measure of the multiverse as a whole to be dominated by Boltzmann brains.
The measurement problem in cosmology also grapples with the ratio of normal observers to abnormally early observers. In measures such as the proper time measure that suffer from an extreme "youngness" problem, the typical observer is a "Boltzmann baby" formed by rare fluctuation in an extremely hot, early universe.
Identifying whether oneself is a "Boltzmann observer"
In Boltzmann brain scenarios, the ratio of Boltzmann brains to "normal observers" is astronomically large. Almost any relevant subset of Boltzmann brains, such as "brains embedded within functioning bodies", "observers who believe they are perceiving 3 K microwave background radiation through telescopes", "observers who have a memory of coherent experiences", or "observers who have the same series of experiences as me", also vastly outnumber "normal observers". Therefore, under most models of consciousness, it is unclear that one can reliably conclude that oneself is not such a "Boltzmann observer", in a case where Boltzmann brains dominate the universe. Even under "content externalism" models of consciousness, Boltzmann observers living in a consistent Earth-sized fluctuation over the course of the past several years outnumber the "normal observers" spawned before a universe's "heat death".
As stated earlier, most Boltzmann brains have "abnormal" experiences; Feynman has pointed out that, if one knows oneself to be a typical Boltzmann brain, one does not expect "normal" observations to continue in the future. In other words, in a Boltzmann-dominated universe, most Boltzmann brains have "abnormal" experiences, but most observers with only "normal" experiences are Boltzmann brains, due to the overwhelming vastness of the population of Boltzmann brains in such a universe.
See also
Swampman – Philosophical thought experiment
References
Further reading
"Disturbing Implications of a Cosmological Constant", Lisa Dyson, Matthew Kleban, and Leonard Susskind, Journal of High Energy Physics 0210 (2002) 011 (at arXiv)
"Is Our Universe Likely to Decay within 20 Billion Years?", Don N. Page, (at arXiv)
"Sinks in the Landscape, Boltzmann Brains, and the Cosmological Constant Problem", Andrei Linde, Journal of Cosmology and Astroparticle Physics, 0701 (2007) 022 (at arXiv)
"Spooks in Space", Mason Inman, New Scientist, Volume 195, Issue 2617, 18 August 2007, pp. 26-29.
"Big Brain Theory: Have Cosmologists Lost Theirs?", Dennis Overbye, 15 January 2008, The New York Times
External links
Human Brain and Universe - Similar Shapes?, ScienceAlert (2020)
"Are You a Boltzmann Brain?", PBS Space Time (2017)
Boltzmann Brains, Matrioshka Brains, Simulation Hypothesis, and a Concept of God
Brain
Philosophy of thermal and statistical physics
Physical cosmology
Thought experiments in philosophy of mind | Boltzmann brain | [
"Physics",
"Chemistry",
"Astronomy"
] | 2,980 | [
"Astronomical sub-disciplines",
"Philosophy of thermal and statistical physics",
"Theoretical physics",
"Astrophysics",
"Thermodynamics",
"Statistical mechanics",
"Physical cosmology"
] |
9,638,730 | https://en.wikipedia.org/wiki/United%20States%20Congressional%20Joint%20Committee%20on%20Atomic%20Energy | The Joint Committee on Atomic Energy (JCAE) was a United States congressional committee that was tasked with exclusive jurisdiction over "all bills, resolutions, and other matters" related to civilian and military aspects of nuclear power from 1946 through 1977. It was established by the United States Atomic Energy Act of 1946, and was the overseer of the United States Atomic Energy Commission. It had been preceded by the Senate Special Committee on Atomic Energy, chaired by Senator Brien McMahon. For its broad powers, it is described as one of the most powerful congressional committees in U.S. history. It was the only permanent joint committee in modern times to have legislative authority.
The panel coupled these legislative powers with exclusive access to the information upon which its highly secretive deliberations were based. In particular its relations with the U.S. Department of Defense and the individual armed services were especially close. The joint committee was also entitled by statute to be kept "fully and currently informed" of all commission activities and vigorously exercised that statutory right, demanding information and attention from the executive branch in a fashion that arguably has no equivalent today.
During the early years of the Cold War, McMahon became the Senate's most prominent expert on atomic energy matters and as chairman exercised considerable influence towards increasing the focus on nuclear weapons as being essential to the American national interest. In this McMahon was aided by the executive director of the committee's staff, William L. Borden, who himself became a powerful figure. Senator Bourke Hickenlooper also served as chair during the early years of the committee and shared a similar sensibility. Indeed regardless of which party controlled the committee, the push for increased production of nuclear materials, and a resultant increase in the American nuclear stockpile, continued.
One major power wielded by the JCAE was the "Legislative Veto". This unique power enabled the JCAE to influence policy decisions while matters were pending. This enabled the JCAE to act as a co-decision maker with the executive branch rather than only providing congressional oversight of actions that had already occurred. The legislative veto power was later found to be unconstitutional by the United States Supreme Court in 1983.
This committee was the main opponent to the creation of the EPA. The Ash Council addressed its resistance to interference by proposing to only transfer over to the new agency the responsibilities of setting radiation standards outside of nuclear power plants.
The JCAE had various subcommittees including Agreements for Cooperation, Communities, Legislation, Military Application, National Security, Raw Materials, Radiation (Special), and Research and Development.
During the 1970s, the committee's role in shaping nuclear policy began to diminish after the Nuclear Regulatory Commission was created to replace the Atomic Energy Commission. Congress soon transferred the bulk of the joint committee's jurisdiction over civilian nuclear power to other standing congressional committees in the House and Senate. The joint committee was finally abolished on August 5, 1977.
Prominent members
Brien McMahon (D-CT), 1946–52: Senator who was legislative author of the Atomic Energy Act of 1946, chairman of the JCAE whenever Democrats controlled Congress (1946, and 1949–52), until his death. Chairman of the JCAE during detection of the first Soviet atomic bomb, the debate over the hydrogen bomb, and the discovery of Klaus Fuchs as a spy.
Bourke Hickenlooper (R-IA), 1946–68: Ranking senator throughout much of its early history; chairman of the JCAE from 1947 to 1948. In 1949, he led a campaign accusing AEC chairman David E. Lilienthal of "incredible mismanagement" of the US nuclear complex.
Committee members, 1946–1977
The joint committee had equal representation between both the House and Senate, with 5 majority and 4 minority members from each house. The committee was chaired by a senator from the majority party until the 83rd Congress, when the chairmanship began to alternate between a majority representative and majority senator.
79th Congress, 1946
80th Congress, 1947–1949
81st Congress, 1949–1951
82nd Congress, 1951–1953
83rd Congress, 1953–1955
84th Congress, 1955–1957
85th Congress, 1957–1959
86th Congress, 1959–1961
87th Congress, 1961–1963
88th Congress, 1963–1965
89th Congress, 1965–1967
90th Congress, 1967–1969
91st Congress, 1969–1971
92nd Congress, 1971–1973
93rd Congress, 1973–1975
94th Congress, 1975–1977
95th Congress, 1977
Staff members
William L. Borden, executive director of staff, 1949–1953: Unusually powerful and influential staff figure who advocated for nuclear weapons development in the United States government. Most known for sending a letter that led to the Oppenheimer security hearing.
See also
Immigration and Naturalization Service v. Chadha
References
External links
Library.stanford.edu: Joint Committee on Atomic Energy Digital Library — hosted by Stanford University.
Governmental nuclear organizations
Atomic Energy
Congress
Congress
Congress
Congress | United States Congressional Joint Committee on Atomic Energy | [
"Engineering"
] | 1,002 | [
"Governmental nuclear organizations",
"Nuclear organizations"
] |
9,639,785 | https://en.wikipedia.org/wiki/Kuroshima%20Research%20Station | Kuroshima Research Station is a marine research institute in Okinawa, Japan, located on the island of Kuroshima. (黒島)
It was established in 1973 as the Yaeyama Marine Park Research Institute, for the purpose of managing and utilising the marine park area in Sekisei (石西) lagoon between Ishigaki (石垣) Island and Iriomote (西表) Island including Kuroshima Island.
From the beginning, it worked as ocean research station, and existed until 2002 under the financial support of Nagoya Railroad Business Operations Co. Ltd.
At present, Kuroshima Research Station belongs to the NPO Sea Turtle Association of Japan, which took over the activities of the institute.
Activities
Some of the institutes activities include 30 years’ research into the nesting of sea turtles, including confirmation of the nesting of the hawksbill sea turtle for the first time in Japan, and confirming the nesting of green sea turtles. They have also researched acanthasters and corals.
In 2005, they sponsored the Japanese Sea Turtle Conference, which is held every year at the location of sea turtles nesting rookeries in Japan.
References
External links
Sea Turtle Association of Japan
Japan Committee for IUCN
Mexican, Japanese and U.S. Fishermen Celebrate Sea Turtle's Epic Journey and Commit to Conservation
The nature of Yaeyama Islands
Turtle conservation organizations
Animal welfare organizations based in Japan
Environmental organizations based in Japan
Environmental organizations established in 1973
1973 establishments in Japan
Marine biology
Research institutes | Kuroshima Research Station | [
"Biology"
] | 299 | [
"Marine biology"
] |
9,639,798 | https://en.wikipedia.org/wiki/Sinus%20%28anatomy%29 | A sinus is a sac or cavity in any organ or tissue, or an abnormal cavity or passage. In common usage, "sinus" usually refers to the paranasal sinuses, which are air cavities in the cranial bones, especially those near the nose and connecting to it. Most individuals have four paired cavities located in the cranial bone or skull.
Etymology
Sinus is Latin for "bay", "pocket", "curve", or "bosom". In anatomy, the term is used in various contexts.
The word "sinusitis" is used to indicate that one or more of the membrane linings found in the sinus cavities has become inflamed or infected. It is however distinct from a fistula, which is a tract connecting two epithelial surfaces. If left untreated, infections occurring in the sinus cavities can affect the chest and lungs.
Sinuses in the body
Paranasal sinuses
Maxillary
Ethmoid
Sphenoid
Frontal
Dural venous sinuses
Anterior midline
Cavernous
Superior petrosal
Inferior petrosal
Central sulcus
Inferior sagittal
Superior sagittal
Straight
Confluence of sinuses
Lateral
Transverse
Sigmoid
Inferior
Occipital
Arterial sinuses
Carotid sinus
Organ-specific spaces
Costodiaphragmatic recess (lung/diaphragm sinus, also known as phrenicocostal sinus)
Renal sinus (drains renal medulla)
Coronary sinus (subdivisions of the pericardium)
Lymphatic spaces
Subcapsular sinus (space between the lymph node and capsule)
Trabecular sinuses (space around the invaginations of the lymphatic capsule)
Medullary sinuses (space between the lymphatic cortex and efferent lymphatic drainage)
Paranasal sinuses
The four paired sinuses or air cavities can be referred to as:
Ethmoid sinus cavities which are located between the eyes.
Frontal sinus cavities which can be found above the eyes (more in the forehead region).
Maxillary sinus cavities are located on either side of the nostrils (cheekbone areas).
Sphenoid sinuses that are located behind the eyes and lie in the deeper recesses of the skull.
Function
The function of the sinus cavities within the cranial bone (skull) is not entirely clear. Beliefs about their possible function include:
Sinus cavities allow for voice resonance
They help filter and add moisture to any air that is inhaled through the nasal passages and in the removal of unwanted particles from the sinus cavities.
Sinus cavities lighten the skull.
Sinus cavities allow space to accommodate for growth
Sinus cavities may serve as shock absorption upon trauma
Sinusitis
If one or more of the paired paranasal sinuses or air cavities becomes inflamed, it leads to an infection called sinusitis. The term "sinusitis" means an inflammation of one or more of the sinus cavities. This inflammation causes an increase in internal pressure within these areas. The pressure is often experienced in the cheek area, eyes, nose, on one side of the head (temple areas), and can result in a severe headache.
When diagnosing a sinus infection, one can identify which sinus cavity the infection is located in by the term given to the cavity. Ethmoiditis refers to an infection in the ethmoid sinus cavity/ies, frontal sinusitis refers to an infection occurring in the frontal sinus cavity/ies, antritis is used to refer to an infection in the maxillary sinus cavity/ies whilst sphenoiditis refers to an infection in the sphenoid sinus cavity/ies.
Classification
Sinusitis can be acute, chronic or recurrent.
Acute: Any sinus infection which lasts for a maximum of three weeks can be referred to as acute sinusitis; with the affected individual displaying symptoms such as congestion, post nasal drip, halitosis, a runny nose as well as sinus pressure and pain in the affected areas.
Chronic: This infection extends beyond the three-week period and if left untreated can persist for years. Certain causes of chronic sinusitis can be allergies that have been left untreated, bacterial or fungal infections within one or more of the sinus cavities or any allergic disorders which targets and increases the sensitivity of the mucous membrane linings which surround the sinus cavities and nasal passages. Symptoms of chronic sinusitis are debilitating headaches, green colored mucus, severe nasal blockages or congestion and heavy pressure experienced in the cheek, forehead, temple and eye regions.
Recurrent: This type of sinus infection is intermittent; a person usually experiences this type of infection numerous times throughout a year with periods of complete relief being experienced for weeks or months between episodes of infection.
Causes
A sinus infection can have a number of causes. Untreated allergies are one of the main contributing factors to the development of sinus infections. A person with a sinus infection often has nasal congestion with thick nasal secretions, fever, and cough (WebMD). Patients can be treated by “reducing the swelling or inflammation in the nasal passages and sinuses, eliminating the infection, promoting drainage from the sinuses, and maintaining open sinuses” (WebMD). Sinusitis can be treated with medications and can also be eliminated by surgery.
Another cause of sinus infections is a result of bacterial invasion within one or more of the sinus cavities. Any bacteria that enter the nasal passages and sinus cavities through the air that is inhaled, are trapped by the mucus secreted by the mucous membranes surrounding these areas. These trapped particles can cause an irritation to these linings resulting in swelling and inflammation. “Bacteria that normally cause acute sinusitis are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis (WebMD). These microorganisms, along with Staphylococcus aureus and some anaerobes (bacteria that live without oxygen), are involved in chronic sinusitis. (WebMD)” Fungi can also cause chronic sinusitis.
Certain abnormalities or trauma related injuries to the nasal cavity can make it difficult for effective drainage of mucus from the sinus cavities. This mucus is then allowed to develop in these areas making the cavity an ideal area in which bacteria can both attach and thrive.
Treatment outlook
Sinusitis or sinus infections usually clear up if treated early and appropriately. Apart from complications, the outlook for acute bacterial sinusitis is good. People may develop chronic sinusitis or have recurrent attacks of acute sinusitis if they suffer with allergies or if they have any “structural or anatomical causes" which predispose them to developing sinus infections.
Viral sinus infections do not, however, respond well to conventional treatments such as antibiotics. When treating fungal sinusitis, an appropriate fungicide is usually administered.
References
Notes
Sinusitis: Causes, Symptoms, Tests, and Treatment. WebMD - Better information. Better health. 06 Nov. 2009
Is a sinus infection contagious? sinusinfectioncontagious.org - 12 Steps to Prevent Sinus Infection
Anatomy | Sinus (anatomy) | [
"Biology"
] | 1,541 | [
"Anatomy"
] |
9,640,452 | https://en.wikipedia.org/wiki/Toddler%20bed | A toddler bed is a small bed designed for toddlers. A child grows capable of escaping an infant bed around one and a half or two years of age, at which they are often transitioned to a toddler bed. They become too large for a toddler bed between the ages of five and seven years, and will then transition to an ordinary bed.
Commonly toddler beds have low side rails (cot sides, possibly removable) on each side to prevent accidental rolling out of the bed while asleep, rather than being fully enclosed like an infant bed. A toddler bed is low to the ground to facilitate safe and easy entry and exit for the occupant. Due to their ground height, they are often referred to as floor beds or montessori beds. The mattress in a toddler bed is often the same size as that in an infant bed. Generally toddler beds range from x to x . As toddlers are learning to express their tastes, licensed or themed beds to appeal to their preferences are available (for example, a racing car bed).
See also
Bassinet, a common precursor bed for newborns
References
Beds
Child safety | Toddler bed | [
"Biology"
] | 235 | [
"Beds",
"Behavior",
"Sleep"
] |
9,640,479 | https://en.wikipedia.org/wiki/Muir%E2%80%93Torre%20syndrome | Muir–Torre syndrome is a rare hereditary, autosomal dominant cancer syndrome that is thought to be a subtype of HNPCC (Lynch syndrome). Individuals are prone to develop cancers of the colon, genitourinary tract, and skin lesions, such as keratoacanthomas and sebaceous tumors. The genes affected are MLH1, MSH2, and more recently, MSH6, and are involved in DNA mismatch repair.
Symptoms
Muir–Torre syndrome is characterized by both:
At least a single sebaceous gland tumor (either an adenoma, an epithelioma, or a carcinoma)
A minimum of one internal malignancy
The Amsterdam criteria are frequently used to diagnose Lynch syndrome and Muir–Torre syndrome. They include the following:
3 or more relatives with an HNPCC-associated cancer (i.e., colorectal, cancer of the endometrium, small bowel, ureter, or renal pelvis)
2 or more successive generations affected by cancer
1 or more persons with cancer is a first-degree relative of the other 2, at least 1 case of colorectal cancer younger than age 50 years, a diagnosis of familial adenomatous polyposis has been excluded, tumors are verified by histologic examination
Muir–Torre syndrome is a genetic condition. Mutations in MLH1 and MSH2 are linked with the disease. These genes code for DNA mismatch repair genes, and mutations increase the risk of developing cancerous qualities.
Many patients who have sebaceous neoplasms with mutations in MSH2 and MLH1 do not in fact have Muir–Torre syndrome. The Mayo Muir–Torre syndrome risk scoring system was devised to improve the positive predictive value of immunohistochemistry and reduce the false positive rate.
The Mayo Muir–Torre risk scoring system assigns points based several characteristics. A score of 2 or greater has a high positive predictive value of Muir–Torre syndrome. A score of 1 or lower is less likely to be Muir–Torre syndrome.
Age of onset of first sebaceous neoplasm: <60 years = 1 point, otherwise 0 points
Total number of sebaceous neoplasms: 1 = 0 points, >2 = 2 points.
Personal history of Lynch related cancers: No = 0 points, Yes = 1 point
Family history of Lynch-related cancer: No = 0 points, Yes = 1 point
The most common internal malignancies associated with Muir–Torre syndrome are: Colorectal (56%), Urogenital (22%), Small Intestine (4%), and Breast (4%). A variety of other internal malignancies have been reported.
Cause
Genetic overlap with Turcot syndrome
A couple studies have been conducted on patients with both Muir–Torre syndrome and Turcot syndrome. It is thought that the two may have some genetic overlap. Both have been associated defects in MLH1 and MSH2 genes.
In one study, a patient with defective MSH2 and MSH6 mismatch repair genes exhibited both syndromes. This is the first case where a patient with genotypic changes consistent with HNPCC has been properly diagnosed with an overlap of both syndromes. Along with neoplasms of the sebaceous gland, this patient developed cerebral neoplasms, characteristic of Turcot syndrome.
Diagnosis
Immunohistochemistry is now being used more often to diagnose patients likely to have Muir–Torre syndrome. Sebaceous neoplasms are only infrequently encountered, and immunohistochemistry is reliable and readily available, so researchers have recommended its use. Routine immunohistochemical detection of DNA mismatch repair proteins help identify hereditary DNA mismatch repair deficiency.
Treatment
Treatment of Muir–Torre syndrome normally consists of oral isotretinoin. The drug has been found to prevent tumor development.
Patients with Muir–Torre syndrome should follow the same stringent screening for colorectal carcinoma and other malignancies as patients with Lynch syndrome. This includes frequent and early colonoscopies, mammograms, dermatologic evaluation, and imaging of the abdomen and pelvis.
Epidemiology
Muir–Torre was observed to occur in 14 of 50 families (28%) and in 14 of 152 individuals (9.2%) with Lynch syndrome, also known as HNPCC.
The two major MMR proteins involved are hMLH1 and hMSH2. Approximately 70% of tumors associated with the MTS have microsatellite instability. While germline disruption of hMLH1 and hMSH2 is evenly distributed in HNPCC, disruption of hMSH2 is seen in greater than 90% of MTS patients.
Gastrointestinal and genitourinary cancers are the most common internal malignancies. Colorectal cancer is the most common visceral neoplasm in Muir–Torre syndrome patients.
Eponym
The syndrome is named for Edward Grainger Muir and Douglas P. Torre. A British physician and surgeon, Muir noted a patient with many keratoacanthomas who went on to develop several internal malignancies at a young age in the 1960s. Torre, a New York dermatologist, presented his findings at a meeting of the New York Dermatologic Society.
It was not until the 1980s when Creighton professor Henry T. Lynch noted a clustering of Muir–Torre syndrome patients in families with Lynch syndrome.
See also
List of cutaneous conditions
List of cutaneous conditions associated with increased risk of nonmelanoma skin cancer
References
External links
Epidermal nevi, neoplasms, and cysts
DNA replication and repair-deficiency disorders
Syndromes | Muir–Torre syndrome | [
"Biology"
] | 1,208 | [
"Senescence",
"DNA replication and repair-deficiency disorders"
] |
9,641,231 | https://en.wikipedia.org/wiki/Greenphone | The Greenphone was a smartphone developed by Trolltech with Qtopia Phone Edition, a GUI and application platform embedded in Linux using mostly free and open source software.
The proprietary software on the phone includes the communications stack and the package manager. However, Trolltech put these components under GPL in version 4.3 of Qtopia, making it possible to run the Greenphone with no proprietary components by updating its software to Qtopia 4.3.
On October 22, 2007, Trolltech announced that it had sold all inventory of Greenphones and would no longer continue production, having achieved its goal of promoting the Qtopia platform and gaining interest from developers. Focus was shifted to developing the Neo FreeRunner phone. Trolltech intends to continue supporting the Qtopia Greenphone community, and alternative hardware, such as the Neo 1973.
The Greenphone was named after Robert Green, an employee of Trolltech at the time, who jokingly suggested it when the company was having trouble agreeing on a name for the phone.
See also
Android (operating system), developed by Google
FIC Neo 1973 a smartphone developed by Openmoko
Openmoko, which can also run Qtopia
Qtopia
External links
Greenphone developer tutorials
Getting Started with the Trolltech Greenphone SDK
References
Open-source mobile phones
Smartphones
Discontinued smartphones
it:GreenPhone | Greenphone | [
"Technology"
] | 277 | [
"Mobile technology stubs",
"Mobile phone stubs"
] |
9,641,508 | https://en.wikipedia.org/wiki/William%20L.%20Jorgensen | William L. Jorgensen (born October 5, 1949, in New York) is a Sterling Professor of Chemistry at Yale University. He is known for his work in the field of computational chemistry. Some of his contributions include the TIP3P, TIP4P, and TIP5P water models, the OPLS force field, free-energy perturbation theory for modelling reactions in solution, protein-ligand binding, and drug design. Jorgensen served as the Editor of the ACS Journal of Chemical Theory and Computation from its founding in 2005 until 2022.
Academic career
Jorgensen earned a bachelor's degree from Princeton University in 1970 and a PhD from Harvard University in 1975 in Chemical Physics while studying under Elias J. Corey. Jorgensen then worked at Purdue University from 1975 to 1990 first as an assistant professor and then later as a Professor. He joined the Yale faculty in 1990 and has remained there since.
Research
Jorgensen's research interests include the calculation of free energy of reactions using quantum mechanics, molecular mechanics, and Metropolis Monte Carlo methods. These methods have application to the calculation of protein-ligand binding affinities. Generally, the research goals involve developing theoretical and computational methods to contribute to the understanding of the structure and reactivity of organic and biomolecular systems. His research group has also pursued de novo drug design, synthesis, and protein crystallography. This drug design being particularly based towards anti-infective, anti-proliferative, and anti-inflammatory agents. Jorgensen was an early contributor to the use of free-energy perturbation calculations for applications several applications including efficient drug lead optimization. Using these methods, he developed improved NNRTIs for HIV treatment. In 2020, Jorgensen's group discovered inhibitors of the main protease of the SARS-CoV-2 virus.
Awards and honors
Jorgensen's work has been recognized by many awards including election to the American Academy of Arts and Sciences, the National Academy of Sciences, and the International Academy of Quantum and Molecular Sciences. He has also received the ACS Award for Computers in Chemical and Pharmaceutical Research, the ACS Hildebrand Award, the Tetrahedron Prize, and Arthur C. Cope Award.
See also
BOSS (molecular mechanics)
OPLS
Sources
External links
William L. Jorgensen Research Group
21st-century American chemists
Living people
1949 births
Yale University faculty
Harvard University alumni
Princeton University alumni
Yale Sterling Professors
Members of the United States National Academy of Sciences
Computational chemists | William L. Jorgensen | [
"Chemistry"
] | 503 | [
"Computational chemistry",
"Theoretical chemists",
"Computational chemists"
] |
9,642,591 | https://en.wikipedia.org/wiki/Glutaredoxin | Glutaredoxins (also known as Thioltransferase) are small redox enzymes of approximately one hundred amino-acid residues that use glutathione as a cofactor. In humans this oxidation repair enzyme is also known to participate in many cellular functions, including redox signaling and regulation of glucose metabolism. Glutaredoxins are oxidized by substrates, and reduced non-enzymatically by glutathione. In contrast to thioredoxins, which are reduced by thioredoxin reductase, no oxidoreductase exists that specifically reduces glutaredoxins. Instead, glutaredoxins are reduced by the oxidation of glutathione. Reduced glutathione is then regenerated by glutathione reductase. Together these components compose the glutathione system.
Like thioredoxin, which functions in a similar way, glutaredoxin possesses an active centre disulfide bond. It exists in either a reduced or an oxidized form where the two cysteine residues are linked in an intramolecular disulfide bond. Glutaredoxins function as electron carriers in the glutathione-dependent synthesis of deoxyribonucleotides by the enzyme ribonucleotide reductase. Moreover, GRX act in antioxidant defense by reducing dehydroascorbate, peroxiredoxins, and methionine sulfoxide reductase. Beside their function in antioxidant defense, bacterial and plant GRX were shown to bind iron-sulfur clusters and to deliver the cluster to enzymes on demand.
In viruses
Glutaredoxin has been sequenced in a variety of viruses. On the basis of extensive sequence similarity, it has been proposed that Vaccinia virus protein O2L is, it seems, a glutaredoxin. Bacteriophage T4 thioredoxin seems to be evolution-related. In position 5 of the pattern T4, thioredoxin has Val instead of Pro.
In plants
Approximately 30 GRX isoforms are described in the model plant Arabidopsis thaliana and 48 in Oryza sativa L. According to their redox-active centre, they are subgrouped in six classes of the CSY[C/S]-, CGFS-, CC-type and 3 groups with additional domains of unknown function. The CC-type GRXs are only found in higher plants. In Arabidopsis, GRXs are involved in flower development and Salicylic acid signalling.
Subfamilies
Glutaredoxin subgroup
Human proteins containing this domain
GLRX; GLRX2; GLRX3; GLRX5; PTGES2
References
External links
Enzyme database entry
EC 1.20.4
Protein domains
Single-pass transmembrane proteins
Antioxidants | Glutaredoxin | [
"Biology"
] | 622 | [
"Protein domains",
"Protein classification"
] |
9,643,090 | https://en.wikipedia.org/wiki/Paddu | Paddu () is an Indian dish made by steaming batter using a mould. It is named variously paniyaram, guliyappa, yeriyappa, gundponglu, bugga, Kuḻi paniyaram (), ponganalu, gunta (), or Tulu: appadadde, appe () . The batter is made of black lentils and rice and is similar in composition to the batter used to make idli and dosa. The dish can also be made spicy with chillies or sweet with jaggery respectively. Paddu is made on a special pan that comes with multiple small indentations.
Gallery
See also
Æbleskiver, a Danish sweet dish
Khanom krok, a Thai dish
Mont lin maya, a Burmese dish
Neyyappam, a fermented South Indian sweet dumpling fried in Ghee
Pinyaram, an Indonesian dish
Poffertjes, a Dutch sweet dish
Takoyaki, a Japanese dish
Unni appam, a fermented South Indian sweet dumpling made with fruits like Jackfruit or Banana
References
External links
Video of the making of kuḻi paniyaram – Wikimedia Commons
ylfd=cb[lv[l ḍg[lh[gh[bṅḥ[l [lṇ\[t\[t;\[b
Indian rice dishes
Fermented foods | Paddu | [
"Biology"
] | 291 | [
"Fermented foods",
"Biotechnology products"
] |
9,644,500 | https://en.wikipedia.org/wiki/Regulatory%20Reform%20%28Fire%20Safety%29%20Order%202005 | The Regulatory Reform (Fire Safety) Order 2005 (SI 2005/1541) is a statutory instrument applicable in England and Wales. The Order places the responsibility on individuals within an organisation to carry out risk assessments to identify, manage and reduce the risk of fire. The Order was made into law on 7 June 2005 and came into force on 1 October 2006.
Guidance for businesses is available in the form of 16 government-published documents, with general guidance, a 5-Step Checklist and 12 documents pertaining specifically to a particular type of business premises. On 5 January 2016, responsibility for fire and rescue policy transferred from the Department for Communities and Local Government to the Home Office, who then became responsible for the guidance. The guidance does not normally apply to domestic premises.
Prior to the Order, under the Fire Precautions Act 1971, all public and commercial buildings, and all non-single-household domestic dwellings (apart from houses in multiple occupation), were required to hold a valid fire safety certificate issued annually after an inspection by the Fire Service. This regime was replaced with assessment by third-party fire-risk assessors contracted by building owners and landlords, with no mandated timeframe for checks, and no mandated professional qualifications.
In 2013, the Fire Service found that 14% of risk assessments were non-compliant with the law, and in 2018 it was found that 500 out of 800 of the UK's fire risk assessors were not registered with accredited bodies.
Guides
The guides available are:
Do you have paying guests?
Fire safety risk assessment: animal premises and stables
Fire safety risk assessment: means of escape for disabled people
Fire safety risk assessment: open-air events and venues
Fire safety risk assessment: transport premises and facilities
Fire safety risk assessment: healthcare premises
Fire safety risk assessment: residential care premises
Fire safety risk assessment: theatres, cinemas and similar premises
Making your premises safe from fire
Fire safety risk assessment: 5-step checklist
Fire safety risk assessment: factories and warehouses
Fire safety risk assessment: large places of assembly
Fire safety risk assessment: small and medium places of assembly
Fire safety risk assessment: educational premises
Fire safety risk assessment: sleeping accommodation
Fire safety risk assessment: offices and shops
See also
Fire services in the United Kingdom
References
External links
The Regulatory Reform (Fire Safety) Order 2005
Fire and rescue in the United Kingdom
Statutory instruments of the United Kingdom
2005 in British law
Fire protection | Regulatory Reform (Fire Safety) Order 2005 | [
"Engineering"
] | 477 | [
"Building engineering",
"Fire protection"
] |
9,644,721 | https://en.wikipedia.org/wiki/Posynomial | A posynomial, also known as a posinomial in some literature, is a function of the form
where all the coordinates and coefficients are positive real numbers, and the exponents are real numbers. Posynomials are closed under addition, multiplication, and nonnegative scaling.
For example,
is a posynomial.
Posynomials are not the same as polynomials in several independent variables. A polynomial's exponents must be non-negative integers, but its independent variables and coefficients can be arbitrary real numbers; on the other hand, a posynomial's exponents can be arbitrary real numbers, but its independent variables and coefficients must be positive real numbers. This terminology was introduced by Richard J. Duffin, Elmor L. Peterson, and Clarence Zener in their seminal book on geometric programming.
Posynomials are a special case of signomials, the latter not having the restriction that the be positive.
References
External links
S. Boyd, S. J. Kim, L. Vandenberghe, and A. Hassibi, A Tutorial on Geometric Programming
Functions and mappings | Posynomial | [
"Mathematics"
] | 243 | [
"Mathematical analysis",
"Functions and mappings",
"Applied mathematics",
"Mathematical objects",
"Mathematical relations",
"Applied mathematics stubs"
] |
9,644,792 | https://en.wikipedia.org/wiki/Hilbert%20projection%20theorem | In mathematics, the Hilbert projection theorem is a famous result of convex analysis that says that for every vector in a Hilbert space and every nonempty closed convex there exists a unique vector for which is minimized over the vectors ; that is, such that for every
Finite dimensional case
Some intuition for the theorem can be obtained by considering the first order condition of the optimization problem.
Consider a finite dimensional real Hilbert space with a subspace and a point If is a or of the function defined by (which is the same as the minimum point of ), then derivative must be zero at
In matrix derivative notation
Since is a vector in that represents an arbitrary tangent direction, it follows that must be orthogonal to every vector in
Statement
Detailed elementary proof
Proof by reduction to a special case
It suffices to prove the theorem in the case of because the general case follows from the statement below by replacing with
Consequences
:
If then
which implies
:
Let where is the underlying scalar field of and define
which is continuous and linear because this is true of each of its coordinates
The set is closed in because is closed in and is continuous.
The kernel of any linear map is a vector subspace of its domain, which is why is a vector subspace of
:
Let
The Hilbert projection theorem guarantees the existence of a unique such that (or equivalently, for all ).
Let so that and it remains to show that
The inequality above can be rewritten as:
Because and is a vector space, and which implies that
The previous inequality thus becomes
or equivalently,
But this last statement is true if and only if every Thus
Properties
Expression as a global minimum
The statement and conclusion of the Hilbert projection theorem can be expressed in terms of global minimums of the followings functions. Their notation will also be used to simplify certain statements.
Given a non-empty subset and some define a function
A of if one exists, is any point in such that
in which case is equal to the of the function which is:
Effects of translations and scalings
When this global minimum point exists and is unique then denote it by explicitly, the defining properties of (if it exists) are:
The Hilbert projection theorem guarantees that this unique minimum point exists whenever is a non-empty closed and convex subset of a Hilbert space.
However, such a minimum point can also exist in non-convex or non-closed subsets as well; for instance, just as long is is non-empty, if then
If is a non-empty subset, is any scalar, and are any vectors then
which implies:
Examples
The following counter-example demonstrates a continuous linear isomorphism for which
Endow with the dot product, let and for every real let be the line of slope through the origin, where it is readily verified that
Pick a real number and define by (so this map scales the coordinate by while leaving the coordinate unchanged).
Then is an invertible continuous linear operator that satisfies and
so that and
Consequently, if with and if then
See also
Notes
References
Bibliography
Convex analysis
Theorems in functional analysis | Hilbert projection theorem | [
"Mathematics"
] | 613 | [
"Theorems in mathematical analysis",
"Theorems in functional analysis"
] |
9,644,994 | https://en.wikipedia.org/wiki/Landfill%20liner | A landfill liner, or composite liner, is intended to be a low permeable barrier, which is laid down under engineered landfill sites. Until it deteriorates, the liner retards migration of leachate, and its toxic constituents, into underlying aquifers or nearby rivers from causing potentially irreversible contamination of the local waterway and its sediments.
Modern landfills generally require a layer of compacted clay with a minimum required thickness and a maximum allowable hydraulic conductivity, overlaid by a high-density polyethylene geomembrane.
The United States Environmental Protection Agency has stated that the barriers "will ultimately fail," while sites remain threats for "thousands of years," suggesting that modern landfill designs delay but do not prevent ground and surface water pollution.
Chipped or waste tires are used to support and insulate the liner.
Types
Different types of liquid trash will vary in their chemical properties and threat posed to the local environment, so any individual landfills may use a variety of different liner systems depending on the type of trash that is collected there. There are two main types of liner systems in use: single-liner systems, and double-liner systems.
Single-liner systems are generally used in landfills which hold rubble waste from construction. Landfills with single-liner systems are not designed to contain harmful liquid wastes such as paint or tar that could easily seep through a single-liner system.
Double-liner systems are usually found in municipal solid waste landfills, as well all hazardous waste landfills. The first layer is constructed to collect the leachate, while the second layer is engineered to be a leak-detection system to ensure that no contaminants seep into the ground.
Components
Composite liners are required to be used in municipal solid waste systems for landfills and use a double liner system which is composed of a leachate system which is a liquid that collects solids from the substance this is passed through it. The leachate system is surrounded in a by a type of solid drainage layer such as gravel which is enclosed by a geomembrane and compressed clay, also known as a geosynthetic clay liner. This geosynthetic clay liner is usually made of sodium bentonite which is compacted in between two thick pieces of geotextile. The next material surrounding the composite liner would be a leak detection system composed of another material like gravel with an additional geomembrane or complex liner. The geomembranes within the composite liner consist of a high-density polyethylene which provide an effective minimization for flow and deliver and helpful barrier which is used on inorganic contaminants. It can be used as a substitute for sand or gravel and also has a very high transmissivity and low storage. The lower surface helps provide an effective leak test once correctly installed. It is also a low permeable vapor and liquid barrier. The geosynthetic clay liners are manufactured by factories and the purpose for it being made of sodium bentonite is that they regulate the movement of liquids in gases within the waste. The geocomposites which are a combination of the geomembranes and geosynthetic liner material also include a layer of bentonite between the middle of the layers of geotextile; however, airspace is allowed to be implemented. It is then topped off with a final cover.
Mechanism
The main role a composite liner performs in a municipal solid waste system for landfills is reducing the amount of leakage through small seep holes that sometimes form in the geomembrane part of the composite liner. The protection layer part serves as a preventer from these holes from forming inside the geomembrane which would allow the waste to leak through the entire liner. It also takes away the pressure and stress which can cause cracking and holes from forming in the membrane as well. An effective liner in a landfill system should be able to control water in terms of movement and protection on the environment. It should be able to regulate the flow away from the waste area and withhold the waste contents as it enters the actual landfill. Due to the effectiveness on how landfills are placed on top of slopes in order for the water to stream downhill and in an emergency, into the actual landfill. Water moves through the landfill and downward through the composite liner. The main purpose for all of this is so that the movement is lateral which lessens the probability for slope catastrophe and the waste leaking down and freely contaminating whatever is in its path. The final cover functions as a way to keep the water out of the contaminate and to control the runoff from entering the system. This helps prevent plants and animals from being harmed by the waste contaminated water, leachate. Using gravity and pumps the leachate is able to be pushed to a sump where it is removed by a pump. When developing composite liners it is extremely important to take in risk factors such as earthquakes and other slope failure problems that could occur. Composite liners are used in municipal solid waste (MSW) landfills to reduce water pollution. A composite liner is made of a geomembrane along with a geosynthetic clay liner. Composite-liner systems are better at reducing leachate migration into the subsoil than either a clay liner or a single geomembrane layer.
Mechanical properties
The primary forms of mechanical degradation associated with geomembranes result from insufficient tensile strength, tear resistance, impact resistance, puncture resistance, and susceptibility to environmental stress cracking (ESC). The ideal method of assessing the amount of liner degradation would be by examining field samples over their service life. Due to the lengths of time required for field sampling tests, various laboratory-accelerated ageing tests have been developed to measure the important mechanical properties.
Tensile strength
Tensile strength represents the ability for a geomembrane to resist tensile stress. Geomembranes are most commonly tested for tensile strength using one of three methods; the uniaxial tensile test described in ASTM D639-94, the wide-strip tensile test described in ASTM D4885-88, and the multiaxial tension test described in ASTM D5617-94. The difference in these three methods lies in the boundaries imposed into the test specimens. Uniaxial tests do not provide lateral restraint during testing and thus tests the sample under uniaxial stress conditions. During the wide-strip test the sample is restrained laterally while the middle portion is unrestrained. The multiaxial tensile test provides a plane stress boundary condition at the edges of the sample. A typical range of tensile strengths in the machine direction are from 225 to 245 lb/in for 60-mil HDPE to 280 to 325 lb/in for 80-mil HDPE.
Tear resistance
Tear resistance of a geomembrane becomes important when it is exposed to high winds or handling stress during installation. There are various ASTM methods for measuring tear resistance of geomembranes, with most common reports using ASTM D1004. Typical tear resistances show a value of 40 to 45 lb for 60-mil HDPE and 50 to 60 lb for 80-mil HDPE.
Impact resistance
Impact resistance provides an assessment of the effects of impacts from falling objects which can either tear or weaken the geomembrane. As with the previous mechanical properties, there are various ASTM methods for assessment. Significantly higher impact resistances are realized when geotextiles are placed above or below the geomembrane. Thicker geomembranes also display higher impact resistances.
Puncture resistance
Puncture resistance of a geomembrane is important due to the heterogeneous material above and below a typical liner. Rough surfaces, such as stones or other sharp objects, may puncture a membrane if it does not have sufficient puncture resistance. Various methods beyond standard ASTM tests are available; one such method, the critical cone height test, measures the maximum height of a cone on which a compressed geomembrane, which is subjected to increasing pressure, does not fail. HDPE samples typically have a critical cone height of around 1 cm.
Environmental stress cracking
Environmental stress cracking is defined as external or internal cracking in plastic induced by applied tensile stress more than its short-term tensile strength. ESC is a fairly common observation in HDPE geomembranes and thus needs to be evaluated carefully. Proper polymeric properties, such as molecular weight, orientation, and distribution, aid in ESC resistance. ASTM D5397 [standard test method for evaluation of stress crack resistance of polyolefin geomembranes using notched constant tensile load (NCTL)] provides the necessary procedure for measuring the ESC resistance of most HDPE geomembranes. The current recommended transition time for an acceptable HDPE geomembrane is around 100 h.
See also
Geomembrane / Pond liner
Bioclogging
Biogas
Daily cover
Landfill mining
Landfills in the United States
Waste compaction
References
Landfill
Waste treatment technology
Water pollution | Landfill liner | [
"Chemistry",
"Engineering",
"Environmental_science"
] | 1,858 | [
"Water treatment",
"Environmental engineering",
"Waste treatment technology",
"Water pollution"
] |
9,645,184 | https://en.wikipedia.org/wiki/Tetrasodium%20tris%28bathophenanthroline%20disulfonate%29ruthenium%28II%29 | Tetrasodium tris(bathophenanthroline disulfonate)ruthenium(II) (Na4Ru(bps)3) is a sodium salt of coordination compound. In this form, it is the salt of a sulfonic acid. This compound is an extension of the phenanthroline series of coordination compounds. Ruthenium(II) tris(bathophenanthroline disulfonate), referring to the anionic fragment, is used as a protein dye in biochemistry for differentiating and detecting different proteins in laboratory settings.
In recent years, 2-D electrophoresis has been widely accepted as a standard procedure to separate complex protein mixtures in proteome studies (Proteomics). Protein visualisation by Ruthenium(II) tris(bathophenthroline disulfonate) has become a firmly established and widely used method in proteomic analysis and a crucial step in gene expression profiling.
For protein detection, it is advantageous to use fluorescent labels containing chromophores which have longer excitation wavelength and emission wavelength than the aromatic amino acids. The dyes used for this important step should combine attributes like good signal to background ratio (contrast), broad linear dynamic range, broad application range, photochemical stability and compatibility to protein identification techniques, e.g. mass spectrometry (MS) or Western blotting.
History
Originally, the ruthenium transition metal complex, ruthenium(II) tris(4,7-diphenyl-1,10-phenanthroline disulfonate) also termed as ruthenium(II) tris(bathophentroline disulfonate) (RuBPS) was synthesized by Bannwarth as a precursor molecule for a dye that was used as a non-radioactive label for oligo nucleotides. Within 5 years, similar transition metal complexes had been recognized as workable protein detection reagents, and shortly afterwards the europium analog of RuBPS was demonstrated as an effective fluorescent protein detection reagent. The first reported use of RuBPS for protein detection appears to be the commercial release of the proprietary Sypro Ruby protein staining solution in 1999. While Sypro Ruby is proprietary & is not stated to have RuBPS as the major component, it is stated to have ruthenium, and Rabilloud et al. synthesized RuPBS and compared it to Sypro Ruby, finding them to be highly similar, albeit not identical, reagents for fluorescent detection of proteins in polyacrylamide gels. Notably, Rabilloud et al. made their comparisons against the first formulation of Sypro Ruby, the second (and presumed current) formulation of Sypro Ruby has the same product numbers (but distinct lot numbers) and an increased performance with diverse fixative solutions.
The fact that RuBPS is not only easy to synthesize but also easy to handle, induced further developments in this field.
Ongoing developments
Lamanda et al. improved the RuBPS staining protocol by selectively destaining the polyacrylamide matrix while the protein content remained tinctured. This new technique entailed a variety of advantages like strong signals, ameliorated signal to background ratio, better linearity and advanced baseline resolution. More recently, heteroleptic ruthenium(II) complexes highly similar to RuBPS were shown to have some improved properties, specifically a broader pH range where they could be used.
References
External links
More information about ruthenium(II) tris(bathophenanthroline disulfonate) staining can be found on
Ruthenium complexes
Fluorescent dyes
Ruthenium(II) compounds
Pyridine complexes
Sulfonic acids
Organic sodium salts | Tetrasodium tris(bathophenanthroline disulfonate)ruthenium(II) | [
"Chemistry"
] | 793 | [
"Salts",
"Organic sodium salts",
"Functional groups",
"Sulfonic acids"
] |
9,645,719 | https://en.wikipedia.org/wiki/Robustification | Robustification is a form of optimisation whereby a system is made less sensitive to the effects of random variability, or noise, that is present in that system's input variables and parameters. The process is typically associated with engineering systems, but the process can also be applied to a political policy, a business strategy or any other system that is subject to the effects of random variability.
Clarification on definition
Robustification as it is defined here is sometimes referred to as parameter design or robust parameter design (RPD) and is often associated with Taguchi methods. Within that context, robustification can include the process of finding the inputs that contribute most to the random variability in the output and controlling them, or tolerance design. At times the terms design for quality or Design for Six Sigma (DFFS) might also be used as synonyms
Principles
Robustification works by taking advantage of two different principles.
Non-linearities
Consider the graph below of a relationship between an input variable x and the output Y, for which it is desired that a value of 7 is taken, of a system of interest. It can be seen that there are two possible values that x can take, 5 and 30. If the tolerance for x is independent of the nominal value, then it can also be seen that when x is set equal to 30, the expected variation of Y is less than if x were set equal to 5. The reason is that the gradient at x = 30 is less than at x = 5, and the random variability in x is suppressed as it flows to Y.
This basic principle underlies all robustification, but in practice there are typically a number of inputs and it is the suitable point with the lowest gradient on a multi-dimensional surface that must be found.
Non-constant variability
Consider a case where an output Z is a function of two inputs x and y that are multiplied by each other.
Z = x y
For any target value of Z there is an infinite number of combinations for the nominal values of x and y that will be suitable. However, if the standard deviation of x was proportional to the nominal value and the standard deviation of y was constant, then x would be reduced (to limit the random variability that will flow from the right hand side of the equation to the left hand side) and y would be increased (with no expected increase random variability because the standard deviation is constant) to bring the value of Z to the target value. By doing this, Z would have the desired nominal value and it would be expected that its standard deviation would be at a minimum: robustified.
By taking advantage of the two principles covered above, one is able to optimise a system so that the nominal value of a systems output is kept at its desired level while also minimising the likelihood of any deviation from that nominal value. This is despite the presence of random variability within the input variables.
Methods
There are three distinct methods of robustification, but a combination that provides the best in results, resources, and time can be used.
Experimental
The experimental approach is probably the most widely known. It involves the identification of those variables that can be adjusted and those variables that are treated as noises. An experiment is then designed to investigate how changes to the nominal value of the adjustable variables can limit the transfer of noise from the noise variables to the output. This approach is attributed to Taguchi and is often associated with Taguchi methods. While many have found the approach to provide impressive results, the techniques have also been criticised for being statistically erroneous and inefficient. Also, the time and effort required can be significant.
Another experimental method that was used for robustification is the Operating Window. It was developed in the United States before the wave of quality methods from Japan came to the West, but still remains unknown to many. In this approach, the noise of the inputs is continually increased as the system is modified to reduce sensitivity to that noise. This increases robustness, but also provides a clearer measure of the variability that is flowing through the system. After optimisation, the random variability of the inputs is controlled and reduced, and the system exhibits improved quality.
Analytical
The analytical approach relies initially on the development of an analytical model of the system of interest. The expected variability of the output is then found by using a method like the propagation of error or functions of random variables. These typically produce an algebraic expression that can be analysed for optimisation and robustification. This approach is only as accurate as the model developed and it can be very difficult if not impossible for complex systems.
The analytical approach might also be used in conjunction with some kind of surrogate model that is based on the results of experiments or numerical simulations of the system.
Numerical
In the numerical approach a model is run a number of times as part of a Monte Carlo simulation or a numerical propagation of errors to predict the variability of the outputs. Numerical optimisation methods such as hill climbing or evolutionary algorithms are then used to find the optimum nominal values for the inputs. This approach typically requires less human time and effort than the other two, but it can be very demanding on computational resources during simulation and optimization.
See also
Sensitivity analysis
Footnotes
References
Clausing (1994) Total Quality Development: A Step-By-Step Guide to World-Class Concurrent Engineering. American Society of Mechanical Engineers.
Clausing, D. (2004) Operating Window: An Engineering Measure for Robustness Technometrics. Vol. 46 [1] pp. 25–31.
Siddall (1982) Optimal Engineering Design. CRC.
Dodson, B., Hammett, P., and Klerx, R. (2014) Probabilistic Design for Optimization and Robustness for Engineers John Wiley & Sons, Inc.
External links
Probabilistic design
Reliability engineering
Quality | Robustification | [
"Engineering"
] | 1,181 | [
"Systems engineering",
"Reliability engineering"
] |
12,095,458 | https://en.wikipedia.org/wiki/Eel%20City | Eel City is the name given to a community of deep-sea eels living amongst hydrothermal vents in the new volcano of Nafanua in American Samoa. It is unique because most hydrothermal vents are predominantly inhabited by invertebrates, whereas there is little invertebrate life in Eel City.
The community of eels was discovered in 2005, when a new volcanic cone, Nafanua, was discovered inside the submerged caldera of Vailulu'u volcanic sea mount. The eels were identified as synapobranchid eels Dysommina rugosa, which are known from trawl samples in both the Atlantic and Pacific oceans, but have never before been studied in their natural habitat. They are deep sea fishes, bottom dwellers, up to 37 cm long.
Preliminary work indicates that they use the vent only as a place to live. They seem to feed not on chemosynthetic bacteria, but on crustaceans that pass by Nafanua's summit in the currents.
During the initial dive in March 2005, one of the discoverers, Hubert Staudigel (a geologist at San Diego's Scripps Institution of Oceanography), commented "I suppose it's possible they migrate up the water column and feed in the water column and migrate back down to the cracks and crevices to hang out. But it seems odd that a deep-sea fish that would normally be experiencing 2- to 5-degree Celsius (35.6 degrees to 41 degrees Fahrenheit) water would be seeking out water that is warmer."
References
Organisms living on hydrothermal vents
Hot springs of American Samoa | Eel City | [
"Biology"
] | 334 | [
"Organisms by adaptation",
"Organisms by habitat",
"Organisms living on hydrothermal vents"
] |
12,096,417 | https://en.wikipedia.org/wiki/Wirtinger%20inequality%20%282-forms%29 | For other inequalities named after Wirtinger, see Wirtinger's inequality.
In mathematics, the Wirtinger inequality, named after Wilhelm Wirtinger, is a fundamental result in complex linear algebra which relates the symplectic and volume forms of a hermitian inner product. It has important consequences in complex geometry, such as showing that the normalized exterior powers of the Kähler form of a Kähler manifold are calibrations.
Statement
Consider a real vector space with positive-definite inner product , symplectic form , and almost-complex structure , linked by for any vectors and . Then for any orthonormal vectors there is
There is equality if and only if the span of is closed under the operation of .
In the language of the comass of a form, the Wirtinger theorem (although without precision about when equality is achieved) can also be phrased as saying that the comass of the form is equal to .
Proof
In the special case , the Wirtinger inequality is a special case of the Cauchy–Schwarz inequality:
According to the equality case of the Cauchy–Schwarz inequality, equality occurs if and only if and are collinear, which is equivalent to the span of being closed under .
Let be fixed, and let denote their span. Then there is an orthonormal basis of with dual basis such that
where denotes the inclusion map from into . This implies
which in turn implies
where the inequality follows from the previously-established case. If equality holds, then according to the equality case, it must be the case that for each . This is equivalent to either or , which in either case (from the case) implies that the span of is closed under , and hence that the span of is closed under .
Finally, the dependence of the quantity
on is only on the quantity , and from the orthonormality condition on , this wedge product is well-determined up to a sign. This relates the above work with to the desired statement in terms of .
Consequences
Given a complex manifold with hermitian metric, the Wirtinger theorem immediately implies that for any -dimensional embedded submanifold , there is
where is the Kähler form of the metric. Furthermore, equality is achieved if and only if is a complex submanifold. In the special case that the hermitian metric satisfies the Kähler condition, this says that is a calibration for the underlying Riemannian metric, and that the corresponding calibrated submanifolds are the complex submanifolds of complex dimension . This says in particular that every complex submanifold of a Kähler manifold is a minimal submanifold, and is even volume-minimizing among all submanifolds in its homology class.
Using the Wirtinger inequality, these facts even extend to the more sophisticated context of currents in Kähler manifolds.
See also
Gromov's inequality for complex projective space
Systolic geometry
Notes
References
Inequalities
Differential geometry
Systolic geometry | Wirtinger inequality (2-forms) | [
"Mathematics"
] | 618 | [
"Binary relations",
"Mathematical relations",
"Inequalities (mathematics)",
"Mathematical problems",
"Mathematical theorems"
] |
12,096,549 | https://en.wikipedia.org/wiki/Service%20Integration%20Maturity%20Model | The Service Integration Maturity Model (SIMM) is a standardized model for organizations to guide their transformation to a service based business model. By having a standard maturity model, it becomes possible for the organizations or industry to benchmark their SIMM levels, to have a roadmap for transformation to assist their planning and for vendors to offer services and software against these benchmarks.
SIMM may also serve as a framework for the transformation process that can be customized to suit the specific needs of organizations and assessments. This process is a simple sequence of steps: configure the assessment framework, determine the initial level of maturity, and determine the target level of maturity and a transformation path from initial to target level.
The Service Integration Maturity Model (SIMM) helps an organization create a roadmap for the incremental transformation of that organisation towards more mature levels of service integration in order to achieve increasing business benefits associated with higher levels of maturity. SIMM is used to determine which organisational characteristics are desirable in order to attain a new level of maturity. This will determine whether problems occurring at the current level can be solved by evolving to a higher level of service integration maturity.
The Open Group has adopted SIMM as the foundation for the Open Group Service Integration Maturity Model (OSIMM), the industry's first collaborative maturity model for SOA adoption.
References
OSIMM
IBM Article
IT Services Guide
IT service management | Service Integration Maturity Model | [
"Technology"
] | 285 | [
"Computer industry",
"IT service management"
] |
12,096,743 | https://en.wikipedia.org/wiki/LiveStation | Livestation was a platform for distributing live television and radio broadcasts over a data network. It was originally developed by Skinkers Ltd. and is now an independent company called Livestation Ltd. The service was originally based on peer-to-peer technology acquired from Microsoft Research. Between mid-June 2013 and mid-July Livestation was unavailable to some subscribers due to technical issues.
In late 2016, the service closed down without notice.
Overview
Livestation aggregated international news channels online and offered them in some ways:
Free to watch: Some channels could be watched for free on the Livestation website or on their desktop player, a freely downloadable video application that presented all the channels through one interface.
Premium service: Some of the free channels were also available on a subscription basis both in higher quality (800 kbit/s) and in lower (256 kbit/s) delivered via an international content distribution network for higher reliability.
Mobile: Livestation launched BBC World News on the iPhone in 16 European countries and Al Jazeera English globally. The apps were available in the iOS AppStore and streamed the live TV channel 24/7 on both Wi-Fi and 3G connections.
Livestation broadcast streams are encoded in VC-1 format (Livestation is not currently using peer-to-peer). Playback controls were overlaid on top of the video stream. Unlike services such as Joost which offer video-on-demand channels, Livestation streams live broadcasts.
Livestation provided a website, mobile website and native applications for the iOS, Android, Nokia and Blackberry handsets. Early models of Samsung TV were also supported. They also provided desktop software available for Windows, Mac (including PowerPC) and Linux. The cross-platform compatibility of the desktop software was facilitated by the Qt framework. Social networking features were later added that include the ability to chat with other viewers and also find out what others are watching through a user-generated rating system. You could search and select the available channels either from the website or from within the software.
In the first quarter of 2011 by 1047 percent, resulting in the first profitable quarter in its history.
Between mid-June and mid-July 2013, Livestation suffered a prolonged series of technical issues and was unavailable to some users.
In early 2015, Livestation re-branded their entire site changing what channels were offered and bringing in an interactive feature. Some stations on the app were not on the main site and vice versa.
Available channels
Stations available until closure and former live TV news channels in the global offering (which comes with a default installation) included, as of 2016:
ABS-CBN News Channel
Al Aan TV
Al-Alam News Network
Al Arabiya
Al Jazeera
Al Jazeera English
Al Jazeera Mubasher
Al Mayadeen
Al Nabaa TV
BBC Arabic
BBC Persian
BBC World News
BBC World Service Radio
CNBC
CNBC Arabiya (EMEA)
Bloomberg TV
BBC News Channel
CCTV News
CNC World
CNN International
C-SPAN
Democratic Voice of Burma
Deutsche Welle TV and radio
eNCA
Euronews
Espreso TV
Fox News Radio
France24
HispanTV
i24news
Kurdast News
Libya TV
NASA TV
NHK World News
One News
Press TV
RFI Afrique and Monde.
Reuters TV
Russia Today
SAMAA TV
Sky News Arabia
Sky News International
TeleSUR
United Nations Television
UNHCR TV
VOA Persian
As of 2016, the Livestation site is closed.
See also
IPTV
Internet Television
TVUnetworks
References
External links
Official website
Live Station Status
Internet television streaming services
Internet properties established in 2008
Internet properties disestablished in 2016
Defunct companies based in London
Defunct video on demand services
Microsoft Research
Television technology | LiveStation | [
"Technology"
] | 747 | [
"Information and communications technology",
"Television technology"
] |
12,097,339 | https://en.wikipedia.org/wiki/C11H17NO3 | {{DISPLAYTITLE:C11H17NO3}}
The molecular formula C11H17NO3 (molar mass: 211.25 g/mol, exact mass: 211.120843 u) may refer to:
BOHD (psychedelic)
2C-O
Dioxethedrin
Isomescaline
Isoprenaline
Mescaline, a natural psychedelic alkaloid
Methoxamine
Orciprenaline
Molecular formulas | C11H17NO3 | [
"Physics",
"Chemistry"
] | 95 | [
"Molecules",
"Set index articles on molecular formulas",
"Isomerism",
"Molecular formulas",
"Matter"
] |
12,097,860 | https://en.wikipedia.org/wiki/Data%20extraction | Data extraction is the act or process of retrieving data out of (usually unstructured or poorly structured) data sources for further data processing or data storage (data migration). The import into the intermediate extracting system is thus usually followed by data transformation and possibly the addition of metadata prior to export to another stage in the data workflow.
Usually, the term data extraction is applied when (experimental) data is first imported into a computer from primary sources, like measuring or recording devices. Today's electronic devices will usually present an electrical connector (e.g. USB) through which 'raw data' can be streamed into a personal computer.
Data sources
Typical unstructured data sources include web pages, emails, documents, PDFs, social media, scanned text, mainframe reports, spool files, multimedia files, etc. Extracting data from these unstructured sources has grown into a considerable technical challenge, where as historically data extraction has had to deal with changes in physical hardware formats, the majority of current data extraction deals with extracting data from these unstructured data sources, and from different software formats. This growing process of data extraction from the web is referred to as "Web data extraction" or "Web scraping".
Imposing structure
The act of adding structure to unstructured data takes a number of forms
Using text pattern matching such as regular expressions to identify small or large-scale structure e.g. records in a report and their associated data from headers and footers;
Using a table-based approach to identify common sections within a limited domain e.g. in emailed resumes, identifying skills, previous work experience, qualifications etc. using a standard set of commonly used headings (these would differ from language to language), e.g. Education might be found under Education/Qualification/Courses;
Using text analytics to attempt to understand the text and link it to other information
See also
Data mining, discovery of patterns in large data sets using statistics, database knowledge or machine learning
Data retrieval, obtaining data from a database management system, often using a query with a set of criteria
Extract, transform, load (ETL), procedure for copying data from one or more sources, transforming the data at the source system, and copying into a destination system
Information extraction, automated extraction of structured information from unstructured or semi-structured machine-readable data, for example using natural language processing to extract content from images, audio or documents
References
Data engineering
Data warehousing | Data extraction | [
"Engineering"
] | 506 | [
"Software engineering",
"Data engineering"
] |
12,098,689 | https://en.wikipedia.org/wiki/Systems%20analyst | A systems analyst, also known as business technology analyst, is an information technology (IT) professional who specializes in analyzing, designing and implementing information systems. Systems analysts assess the suitability of information systems in terms of their intended outcomes and liaise with end users, software vendors and programmers in order to achieve these outcomes. A systems analyst is a person who uses analysis and design techniques to solve business problems using information technology. Systems analysts may serve as change agents who identify the organizational improvements needed, design systems to implement those changes, and train and motivate others to use the systems.
Industry
, the sectors employing the greatest numbers of computer systems analysts were state government, insurance, computer system design, professional and commercial equipment, and company and enterprise management. The number of jobs in this field is projected to grow from 487,000 as of 2009 to 650,000 by 2016. According to the U.S. Bureau of Labor Statistics (BLS), Occupational Outlook predicts the need for Computer Systems Analysts as growing 25% in 2012 to 2022 and gradually decreasing their estimates and now predict the years 2022 to 2032 as only 10% growth. Saying "Many of those openings are expected to result from the need to replace workers who transfer to different occupations or exit the labor force, such as to retire."
This job ranked third best in a 2010 survey, fifth best in the 2011 survey, 9th best in the 2012 survey and the 10th best in the 2013 survey.
See also
Business analyst
Change management analyst
Data analyst
Software analyst
References
External links
Computer Systems Analysts in the Occupational Outlook Handbook from the Bureau of Labor Statistics, a unit of the United States Department of Labor
Systems analysis
Business occupations
Computer occupations
de:Systemanalyse#Informatik | Systems analyst | [
"Technology"
] | 351 | [
"Computer occupations"
] |
12,098,816 | https://en.wikipedia.org/wiki/Damage%20mechanics | Damage mechanics is concerned with the representation, or modeling, of damage of materials that is suitable for making engineering predictions about the initiation, propagation, and fracture of materials without resorting to a microscopic description that would be too complex for practical engineering analysis.
Damage mechanics illustrates the typical engineering approach to model complex phenomena. To quote Dusan Krajcinovic, "It is often argued that the ultimate task of engineering research is to provide not so much a better insight into the examined phenomenon but to supply a rational predictive tool applicable in design." Damage mechanics is a topic of applied mechanics that relies heavily on continuum mechanics. Most of the work on damage mechanics uses state variables to represent the effects of damage on the stiffness and remaining life of the material that is damaging as a result of thermomechanical load and ageing. The state variables may be measurable, e.g., crack density, or inferred from the effect they have on some macroscopic property, such as stiffness, coefficient of thermal expansion, remaining life, etc. The state variables have conjugate thermodynamic forces that motivate further damage. Initially the material is pristine, or intact. A damage activation criterion is needed to predict damage initiation. Damage evolution does not progress spontaneously after initiation, thus requiring a damage evolution model. In plasticity like formulations, the damage evolution is controlled by a hardening function but this requires additional phenomenological parameters that must be found through experimentation, which is expensive, time consuming, and virtually no one does. On the other hand, micromechanics of damage formulations are able to predict both damage initiation and evolution without additional material properties.
Creep continuum damage mechanics
When mechanical structures are exposed to temperatures exceeding one-third of the melting temperature of the material of construction, time-dependent deformation (creep) and associated material degradation mechanisms become dominant modes of structural failure. While these deformation and damage mechanisms originate at the microscale where discrete processes dominate, practical application of failure theories to macroscale components is most readily achieved using the formalism of continuum mechanics. In this context, microscopic damage is idealized as a continuous state variable defined at all points within a structure. State equations are defined which govern the time evolution of damage. These equations may be readily integrated into finite element codes to analyze the damage evolution in complex 3D structures and calculate how long a component may safely be used before failure occurs.
Lumped damage state variable
L. M. Kachanov and Y. N. Rabotnov suggested the following evolution equations for the creep strain ε and a lumped damage state variable ω:
where is the creep strain rate, is the creep-rate multiplier, is the applied stress, is the creep stress exponent of the material of interest, is the rate of damage accumulation, is the damage-rate multiplier, and is the damage stress exponent.
In this simple case, the strain rate is governed by power-law creep with the stress enhanced by the damage state variable as damage accumulates. The damage term ω is interpreted as a distributed loss of load bearing area which results in an increased local stress at the microscale. The time to failure is determined by integrating the damage evolution equation from an initial undamaged state to a specified critical damage . If is taken to be 1, this results in the following prediction for a structure loaded under a constant uniaxial stress :
Model parameters and n are found by fitting the creep strain rate equation at zero damage to minimum creep rate measurements. Model parameters and m are found by fitting the above equation to creep rupture life data.
Mechanistically informed damage state variables
While easy to apply, the lumped damage model proposed by Kachanov and Robotnov is limited by the fact that the damage state variable cannot be directly tied to a specific mechanism of strain and damage evolution. Correspondingly, extrapolation of the model beyond the original dataset of test data is not justified. This limitation was remedied by researchers such as A.C.F. Cocks, M.F. Ashby, and B.F. Dyson, who proposed mechanistically informed strain and damage evolution equations. Extrapolation using such equations is justified if the dominant damage mechanism remains the same at the conditions of interest.
Void-growth by power-law creep
In the power-law creep regime, global deformation is controlled by glide and climb of dislocations. If internal voids are present within the microstructure, global structural continuity requires that the voids must both elongate and expand laterally, further reducing the local section. When cast in the damage mechanics formalism, the growth of internal voids by power-law creep can be represented by the following equations.
where is the creep-rate multiplier, is the applied stress, n is the creep stress exponent, is the average initial void radius, and d is the grain size.
Void-growth by boundary diffusion
At very high temperature and/or low stresses, void growth on grain boundaries is primarily controlled by the diffusive flux of vacancies along the grain boundary. As matter diffuses away from the void and plates onto the adjacent grain boundaries, a roughly spherical void is maintained by rapid diffusion of vacancies along the surface of the void. When cast in the damage mechanics formalism, the growth of internal voids by boundary diffusion can be represented by the following equations.
where is the creep-rate multiplier, is the applied stress, is the center-to-center void spacing, is the grain size, is the grain-boundary diffusion coefficient, is the grain boundary thickness, is the atomic volume, is the Boltzmann constant, and is the absolute temperatures. It is noted that factors present in are very similar to the Coble creep pre-factors due to the similarity of the two mechanisms.
Precipitate coarsening
Many modern steels and alloys are designed such that precipitates will precipitate either within the matrix or along grain boundaries during casting. These precipitates restrict dislocation motion and, if present on grain boundaries, grain boundary sliding during creep. Many precipitates are not thermodynamically stable and grow via diffusion when exposed to elevated temperatures. As the precipitates coarsen, their ability to restrict dislocation motion decreases as the average spacing between particles increases, thus decreasing the required Orowan stress for bowing. In the case of grain boundary precipitates, precipitate growth means that fewer grain boundaries are impeded from grain boundary sliding. When cast into the damage mechanics formalism, precipitation coarsening and its effect on strain rate may be represented by the following equations.
where is the creep-rate multiplier, is the applied stress, is the creep-rate stress exponent, is a parameter linking the precipitation damage to the strain rate, determines the rate of precipitate coarsening.
Combining damage mechanisms
Multiple damage mechanism can be combined to represent a broader range of phenomena. For instance, if both void-growth by power-law creep and precipitate coarsening are relevant mechanisms, the following combined set of equations may be used:
Note that both damage mechanisms are included in the creep strain rate equation. The precipitate coarsening damage mechanisms influences the void-growth damage mechanism as the void-growth mechanism depends on the global strain rate. The precipitate growth mechanisms is only time and temperature dependent and hence does not depend on the void-growth damage .
Multiaxial effects
The preceding equations are valid under uniaxial tension only. When a multiaxial state of stress is present in the system, each equation must be adapted so that the driving multiaxial stress is considered. For void-growth by power-law creep, the relevant stress is the von Mises stress as this drives the global creep deformation; however, for void-growth by boundary diffusion, the maximum principal stress drives the vacancy flux.
See also
Lumped damage mechanics
Failure analysis
Critical plane analysis
References
Continuum mechanics
Materials degradation
Mechanical failure | Damage mechanics | [
"Physics",
"Materials_science",
"Engineering"
] | 1,653 | [
"Continuum mechanics",
"Classical mechanics",
"Materials science",
"Mechanical engineering",
"Materials degradation",
"Mechanical failure"
] |
12,098,877 | https://en.wikipedia.org/wiki/Tanzania%20Atomic%20Energy%20Commission | The Tanzania Atomic Energy Commission (also known by its acronym, TAEC) is the regulatory body responsible for all atomic energy matters in the United Republic of Tanzania. It was established under the Atomic Energy Act No. 7 of 2003. The formation of TAEC in 2003 came into effect after the repeal of the Protection from Radiation Act No. 5 of 1983, which created the National Radiation Commission (NRC) in 1983. The TAEC was established with additional responsibilities, including the control of the use of ionizing and non-ionizing radiation sources, as well as the promotion of safe and peaceful applications of atomic energy and nuclear technology. Additionally, TAEC regulates the safe and peaceful uses of atomic energy and promotes and expands the contribution of atomic energy and nuclear technology to health and prosperity throughout the United Republic of Tanzania. The first President of Tanzania, Mwalimu Julius Kambarage Nyerere, signed the Protection from Radiation Act on May 9, 1983, to control the use of radioactive material and for other matters connected with the protection of persons from harm resulting from ionizing radiation in the United Republic of Tanzania. This act gave the National Radiation Commission complete control over the use of radioactive materials, the installation of plants, the importation of nuclear installations, and the operation of nuclear installations.
During its early days, the NRC played a key role in coordinating the medical and industrial application of ionizing radiation by carrying out regular inspections at ionizing radiation facilities with a view to ensuring the protection of workers. students, and the general public from harm resulting from ionizing radiation. On importation of nuclear instillations, the NRC was responsible to take into consideration all applications for and granting licenses to persons intending to import or use atomic or other radioactive plants, installations and maintain a register or registers of importers, users and operators, of nuclear or other radioactive plants, installations, apparatus or other radioactive materials.
See also
Energy law
Nuclear energy policy
References
Ministry of Communication, Science & Technology
External links
Tanzania Atomic Energy Commission
Nuclear energy in Tanzania
Government of Tanzania
Governmental nuclear organizations
Arusha | Tanzania Atomic Energy Commission | [
"Engineering"
] | 418 | [
"Governmental nuclear organizations",
"Nuclear organizations"
] |
12,099,794 | https://en.wikipedia.org/wiki/Tin-glazed%20pottery | Tin-glazed pottery is earthenware covered in lead glaze with added tin oxide which is white, shiny and opaque (see tin-glazing for the chemistry); usually this provides a background for brightly painted decoration. It has been important in Islamic and European pottery, but very little used in East Asia. The pottery body is usually made of red or buff-colored earthenware and the white glaze imitated Chinese porcelain. The decoration on tin-glazed pottery is usually applied to the unfired glaze surface by brush with metallic oxides, commonly cobalt oxide, copper oxide, iron oxide, manganese dioxide and antimony oxide. The makers of Italian tin-glazed pottery from the late Renaissance blended oxides to produce detailed and realistic polychrome paintings.
The earliest tin-glazed pottery appears to have been made in Iraq in the 9th century, the oldest fragments having been excavated during the First World War from the palace of Samarra about fifty miles north of Baghdad. From there it spread to Egypt, Persia and Spain before reaching Italy in mid-15th century, early Renaissance, Holland in the 16th century and England, France and other European countries shortly after.
The development of white, or near white, firing bodies in Europe from the late 18th century, such as creamware by Josiah Wedgwood, and increasingly cheap European porcelain and Chinese export porcelain, reduced the demand for tin-glaze Delftware, faience and majolica.
The rise in the cost of tin oxide during the First World War led to its partial substitution by zirconium compounds in the glaze.
Names
Tin-glazed pottery of different periods and styles is known by different names. The pottery from Muslim Spain is known as Hispano-Moresque ware. The decorated tin-glaze of Renaissance Italy is called maiolica, sometimes pronounced and spelt majolica by English speakers and authors. When the technique was taken up in the Netherlands, it became known as delftware as much of it was made in the town of Delft. Dutch potters brought it to England in around 1600, and wares produced there are known as English delftware or galleyware. In France it was known as faience.
The word maiolica is thought to have come from the medieval Italian word for Majorca, an island on the route for ships that brought Hispano-Moresque wares to Italy from Valencia in the 15th and 16th centuries, or from the Spanish obra de Mallequa, the term for lustered ware made in Valencia under the influence of Moorish craftsmen from Malaga. During the Renaissance, the term maiolica was adopted for Italian-made luster pottery copying Spanish examples, and, during the 16th century, its meaning shifted to include all tin-glazed earthenware.
Because of their identical names, there has been some confusion between tin-glazed majolica/maiolica and the lead-glazed majolica made in England and America in the 19th century, but they are different in origin, technique, style and history. In the late 18th century, old Italian tin-glazed maiolica became popular among the British, who referred to it by the anglicized pronunciation majolica. The Minton pottery copied it and applied the term majolica ware to their product. At the Great Exhibition of 1851, Minton launched the colorful lead-glazed earthenware which they called Palissy ware, soon also to become known as majolica. So now there were two distinct products with the same name. "In the 1870s, the curators of the South Kensington Museum returned to the original Italian 'maiolica' with an 'i' to describe all Italian tin-glazed earthenware, doubtless to stress the Italian pronunciation and to avoid confusion with contemporary majolica."
A style of brightly-coloured 19th-century lead-glazed earthenware was also called "majolica", and is now known as Victorian majolica
W.B. Honey (Keeper of Ceramics at the Victoria & Albert Museum, 1938–1950) wrote of maiolica that, "By a convenient extension and limitation the name may be applied to all tin-glazed ware, of whatever nationality, made in the Italian tradition … the name faïence (or the synonymous English 'delftware') being reserved for the later wares of the 17th Century onwards, either in original styles (as in the case of the French) or, more frequently, in the Dutch-Chinese (Delft) tradition." The term maiolica is sometimes applied to modern tin-glazed ware made by studio potters.
Hispano-Moresque ware
The Moors introduced tin-glazed pottery to Spain after the conquest of 711.
Hispano-Moresque ware is generally distinguished from the pottery of Christendom by the Islamic character of its decoration, though as the dish illustrated shows, it was also made for the Christian market.
Hispano-Moresque shapes of the 15th century included the albarello (a tall jar), luster dishes with coats of arms, made for wealthy Italians and Spaniards, jugs, some on high feet (the citra and the grealet), a deep-sided dish (the lebrillo de alo) and the eared bowl (cuenco de oreja).
With the Spanish conquest of Mexico, tin-glazed pottery came to be produced in the Valley of Mexico as early as 1540, at first in imitation of the ceramics imported from Seville.
Although the Moors were expelled from Spain in the early 17th century, the Hispano-Moresque style survived in the province of Valencia. Later wares usually have a coarse reddish-buff body, dark blue decoration and luster.
Maiolica
The 15th-century wares that initiated maiolica as an art form were the product of a long technical evolution, in which medieval lead-glazed wares were improved by the addition of tin oxides under the initial influence of Islamic wares imported through Sicily. Such archaic wares are sometimes dubbed proto-maiolica. During the later 14th century, the limited palette of colors was expanded from the traditional manganese purple and copper green to embrace cobalt blue, antimony yellow and iron-oxide orange. Sgraffito wares were also produced, in which the white tin-oxide slip was decoratively scratched to produce a design from the revealed body of the ware.
Refined production of tin-glazed earthenware made for more than local needs was concentrated in central Italy from the later 13th century, especially in the contada of Florence. The importance of the city itself in the production of maiolica declined in the second half of the 15th century, perhaps because of local deforestation. Italian cities encouraged the start of a new pottery industry by offering tax relief, citizenship, monopoly rights and protection from outside imports. Production scattered among small communes and, after the mid-15th century, at Faenza, Arezzo and Siena. Faenza, which gave its name to faience, was the only fair-sized city in which the ceramic industry became a major economic component. Bologna produced lead-glazed wares for export. Orvieto and Deruta both produced maioliche in the 15th century. In the 16th century, maiolica production was established at Castel Durante, Urbino, Gubbio and Pesaro. Some maiolica was produced as far north as Padua, Venice and Turin and as far south as Palermo and Caltagirone in Sicily. In the 17th century Savona began to be a prominent place of manufacture.
Some of the principal centres of production (e.g. Deruta and Montelupo) still produce maiolica, which is sold in quantity in Italian tourist areas.
Delftware
Delftware was made in the Netherlands from the 16th to the 18th centuries. The main period of manufacture was 1600-1780, after which it was succeeded by white stoneware and porcelain.
The earliest tin-glazed pottery in the Netherlands was made in Antwerp in 1512. The manufacture of painted pottery may have spread from the southern to the northern Netherlands in the 1560s. It was made in Middleburg and Haarlem in the 1570s and in Amsterdam in the 1580s. Much of the finer work was produced in Delft, but simple everyday tin-glazed pottery was made in such places as Gouda, Rotterdam, Amsterdam and Dordrecht.
The Guild of St. Luke, to which painters in all media had to belong, admitted ten master potters in the thirty years between 1610 and 1640 and twenty in the nine years 1651 to 1660. In 1654 a gunpowder explosion in Delft destroyed many breweries, and, as the brewing industry was in decline, their premises became available to pottery makers.
From about 1615, the potters began to coat their pots completely in white tin glaze instead of covering only the painting surface and coating the rest with clear glaze. They then began to cover the tin glaze with a coat of clear glaze which gave depth to the fired surface and smoothness to cobalt blues, ultimately creating a good resemblance to porcelain.
Although Dutch potters did not immediately imitate Chinese porcelain, they began to do after the death of the Emperor Wan-Li in 1619, when the supply to Europe was interrupted. Delftware inspired by Chinese originals persisted from about 1630 to the mid-18th century alongside European patterns.
Delftware ranged from simple household items to fancy artwork. Pictorial plates were made in abundance, illustrated with religious motifs, native Dutch scenes with windmills and fishing boats, hunting scenes, landscapes and seascapes. The Delft potters also made tiles in vast numbers (estimated at eight hundred million over a period of two hundred years); many Dutch houses still have tiles that were fixed in the 17th and 18th centuries.
Delftware became popular, was widely exported in Europe and reached China and Japan. Chinese and Japanese potters made porcelain versions of Delftware for export to Europe.
By the late 18th century, Delftware potters had lost their market to British porcelain and the new white earthenware.
There are good collections of old Delftware in the Rijksmuseum and the Victoria and Albert Museum.
English delftware
English delftware was made in the British Isles between about 1550 and the late 18th century. The main centers of production were London, Bristol and Liverpool with smaller centers at Wincanton, Glasgow and Dublin.
John Stow's Survey of London (1598) records the arrival in 1567 of two Antwerp potters, Jasper Andries and Jacob Jansen, in Norwich, where they made "Gally Paving Tiles, and vessels for Apothecaries and others, very artificially". In 1579 Jansen applied to Queen Elizabeth I for the sole right to practice "galleypotting" (at the time "galliware" was the term in English for delftware) in London and soon set up a workshop at Aldgate to the east of the city. There were already other Flemish potters in London, two of them in Southwark recorded in 1571 as "painters of pottes".
English delftware pottery and its painted decoration is similar in many respects to that from Holland, but its peculiarly English quality has been commented upon: "... there is a relaxed tone and a sprightliness which is preserved throughout the history of English delftware; the overriding mood is provincial and naive rather than urbane and sophisticated." Its methods and techniques were less sophisticated than those of its continental counterparts.
The earliest known piece with an English inscription is a dish dated 1600 in the London Museum. It is painted in blue, purple, green, orange and yellow and depicts the Tower of London and Old London Bridge, surrounded by the words, "THE ROSE IS RED THE LEAVES ARE GRENE GOD SAVE ELIZABETH OUR QUEENE" and an Italianate border of masks and leaves. The rim is decorated with dashes of blue and can be considered the first in series of large decorated dishes so painted and called blue-dash chargers. Blue-dash chargers, usually between about 25 and 35 cm in diameter with abstract, floral, religious, patriotic or topographical motifs, were produced in quantity by London and Bristol potters until the early 18th century. As they were kept for decoration on walls, dressers and side-tables, many have survived and they are well represented in museum collections.
Smaller and more everyday wares were also made: paving tiles, mugs, drug jars, dishes, wine bottles, posset pots, salt pots, candlesticks, fuddling cups, puzzle jugs, barber's bowls, pill slabs, bleeding bowls, porringers, and flower bricks.
Towards the end of the 17th century, changing taste led to the replacement of apothecary pots, paving tiles and large dishes by polite tablewares, delicate ornaments, punch bowls, teapots, cocoa pots and coffee-pots.
There are good examples of English delftware in the Victoria and Albert Museum, the British Museum, the Ashmolean Museum and the Fitzwilliam Museum.
Faience
In France, the first well-known painter of faience was Masseot Abaquesne, established in Rouen in the 1530s. Nevers faience and Rouen faience were the leading French centres of faience manufacturing in the 17th century, both able to supply wares to the standards required by the court and nobility. Many others developed from the early 18th century, led in 1690 by Quimper in Brittany, followed by Moustiers, Marseille, Strasbourg and Lunéville and many smaller centres.
The products of faience manufactories are identified by the usual methods of ceramic connoisseurship: the character of the clay body, the character and palette of the glaze, and the style of decoration, faïence blanche being left in its undecorated fired white slip. Faïence parlante (especially from Nevers) bears mottoes often on decorative labels or banners. Apothecary wares, including albarelli, can bear the names of their intended contents, generally in Latin and often so abbreviated to be unrecognizable to the untutored eye. Mottoes of fellowships and associations became popular in the 18th century, leading to the faïence patriotique that was a specialty of the years of the French Revolution.
The industry was in crisis by the start of the French Revolution in 1789, as production of French porcelain had greatly increased, and its prices were reducing, though it still cost much more than faience. At the same time a commercial treaty with Britain in 1786 led to a flood of imports of English creamware which was not only superior to faience in terms of weight and strength, but cheaper. In the 19th century production revived, but faience was rarely fashionable again.
Current use
Popular and folk forms have continued in many countries, including the Mexican Talavera.
In the 20th century there were changes in the formulation of tin-glaze and several artist potters began to work in the medium of tin-glazed pottery.
The cost of tin oxide rose considerably during the 1918-1918 war and resulted in a search for cheaper alternatives. The first successful replacement was zirconia and later zircon. Whilst zirconium compounds are not as effective opacifiers as tin oxide, their relatively low price has led to a gradual increase in their use, with an associated reduction in the use of tin oxide. The whiteness resulting from the use of zirconia has been described as more "clinical" than that from tin oxide and is preferred in some applications. Nevertheless, tin oxide still finds use in ceramic manufacture and has been widely used as the opacifier in sanitaryware, with up to 6% used in glazes. Otherwise, tin oxide in glazes, often in conjunction with zircon compounds, is generally restricted to specialist low temperature applications and use by studio potters.
In England at the end of the nineteenth century, William De Morgan re-discovered the technique of firing luster on tin-glaze "to an extraordinarily high standard". Since the beginning of the 20th century there has been a revival of pottery-making in Orvieto and Deruta, the traditional centres of tin-glazed ceramics in Italy, where the shapes and designs of the medieval and renaissance period are reproduced. In the 1920s and 1930s, Roger Fry, Vanessa Bell and Duncan Grant decorated tin-glazed pottery for the Omega Workshops in London. Picasso produced and designed much tin-glazed pottery at Vallauris in the south of France in the 1940s and 1950s. At the Central School of Arts and Crafts, London, Dora Billington encouraged her students, including William Newland and Alan Caiger-Smith, to use tin-glaze decoration. In Britain during the 1950s Caiger-Smith, Margaret Hine, Nicholas Vergette and others including the Rye Pottery made tin-glazed pottery, going against the trend in studio pottery towards stoneware. Subsequently, Caiger-Smith experimented with the technique of reduced lustre on tin glaze, which had been practiced in Italy until 1700 and Spain until 1800 and had then been forgotten. Caiger-Smith trained several potters at his Aldermaston Pottery and published Tin-glaze Pottery which gives a history of maiolica, delftware and faience in Europe and the Islamic world. A selection of tin glaze pottery by contemporary Studio potters is given Tin-glazed Earthenware by Daphne Carnegy.
The pottery Royal Tichelaar Makkum, located in Makkum, Friesland, continue the production of Delftware using tin-glazed earthenware.
Gallery of modern examples
See also
Azulejo
Faience
Islamic pottery
Lusterware
Lead-glazed earthenware
Tin glaze
References
Further reading
Anscombe, Isabelle, Omega and After, (Thames and Hudson, 1981)
Blake, Hugo, "The archaic maiolica of North-Central Italy: Montalcino, Assisi and Tolentino" in Faenza, 66 (1980) pp. 91–106
Caiger-Smith, Alan, Lustre Pottery: Technique, Tradition and Innovation in Islam and the Western World (Faber and Faber, 1985)
Carnegy, Daphne, Tin-glazed Earthenware (A&C Black/Chilton Book Company, 1993)
Cohen, David Harris, and Hess, Catherine, A Guide To Looking At Italian Ceramics (J. Paul Getty Museum in association with British Museum Press, 1993)
Goldthwaite, Richard A., "The Economic and Social World of Italian Renaissance Maiolica", in Renaissance Quarterly, 42.1 (Spring 1989)
Lane, Arthur, French Faïence, 1948, Faber & Faber
Lister, Florence C. and Lister, Robert H. Lister, Sixteenth Century Maiolica Pottery in the Valley of Mexico (Tucson: Anthropological Papers of the University of Arizona, 1982)
McCully, Marylin (ed.), Picasso: Painter and Sculptor in Clay (Royal Academy of Arts, 1998)
Musacchio, Jacqueline Marie, Marvels of Maiolica: Italian Renaissance Ceramics from the Corcoran Gallery of Art (Bunker Hill Publishing, 2004)
Piccolpasso, Cipriano, The Three Books of the Potter's Art (trans. A. Caiger Smith and R. Lightbown) (Scolar Press, 1980)
Whitehouse, David, "Proto-maiolica" in Faenza, 66 (1980), pp. 77–83
Arabic pottery
Italian pottery
History of glass
Types of pottery decoration
Ceramic glazes
Pottery | Tin-glazed pottery | [
"Chemistry"
] | 4,029 | [
"Ceramic glazes",
"Coatings"
] |
12,100,059 | https://en.wikipedia.org/wiki/HydroGeoSphere | HydroGeoSphere (HGS) is a 3D control-volume finite element groundwater model, and is based on a rigorous conceptualization of the hydrologic system consisting of surface and subsurface flow regimes. The model is designed to take into account all key components of the hydrologic cycle. For each time step, the model solves surface and subsurface flow, solute and energy transport equations simultaneously, and provides a complete water and solute balance.
History
The original name for the code was FRAC3DVS, which was created by René Therrien in 1992. The code was further developed jointly at the University of Waterloo and the Laval University, and was primarily used for academic research. It was renamed to HydroGeoSphere in 2002 with the implementation of 2D surface water flow and transport. In 2012, the software became commercialized under the support and management of Aquanty Inc.
Governing equations
In order to accomplish the integrated analysis, HydroGeoSphere utilizes a rigorous, mass conservative modeling approach that fully couples the surface flow and transport equations with the 3-D, variably saturated subsurface flow and transport equations. This approach is significantly more robust than previous conjunctive approaches that rely on linkage of separate surface and subsurface modeling codes.
Groundwater Flow
HydroGeoSphere assumes that the subsurface flow equation in a porous medium is always solved during a simulation, either for fully saturated or variably saturated flow conditions. The subsurface flow equation can be expanded to incorporate discrete fractures, a second interacting porous continuum, wells, tile drains and surface flow. The following assumptions are made for subsurface flow:
The fluid is essentially incompressible.
The porous medium and fractures (or macropores), if present, are non-deformable.
The system is under isothermal conditions.
The air phase is infinitely mobile.
The Richards’ equation is used to describe three-dimensional transient subsurface flow in a variably saturated porous medium:
The fluid flux, , is represented by the Darcy's law shown as:
where is the volumetric fraction of the total porosity occupied by the porous medium, is the internal fluid exchange rate (e.g. surface water, wells, and tile drains), is the external fluid outside of the model domain, is the saturated water content, is the degree of saturation, is the hydraulic conductivity tensor, is the relative permeability of the medium calculated as a function of saturation, is the pressure head, and is the elevation head.
Surface water flow
Areal surface water flow is represented in HydroGeoSphere by a two-dimensional depth-averaged flow equation, which is the diffusion-wave approximation of the Saint Venant equation for surface water flow. HydroGeoSphere's surface water flow component is implemented with the following assumptions:
Depth-averaged flow velocities
Hydrostatic pressure distribution vertically
Mild slope
Dominant bottom shear stresses.
The surface flow components are solved by the following three equations, which are given by the following mass balance equation:
coupled with the momentum equations, neglecting inertia terms, for the x-direction:
and for the y-direction:
where is the surface flow domain porosity, is the water surface elevation, and are the vertically averaged flow velocities in the x and y directions, is the depth of surface water flow, is the internal fluid exchange, and is the external fluid exchange. The surface conductances, and are approximated by either the Manning or Chezy equation.
Solute transport
Three-dimensional transport of solutes is described by the modified reactive transport advective-dispersion equation:
where is the solute concentration, is the first-order decay constant, is the external source or sink term, is the internal solute transfer between domains, is the retardation factor, is the diffusion coefficient, and designates parent species for the case of a decay chain.
Heat transport
Graf [2005] incorporated heat transport within the saturated-zone flow regime into HydroGeoSphere together with temperature-dependent fluid properties, such as viscosity and density. The model’s capability was successfully demonstrated for the case of thermohaline flow and transport in porous and fractured porous media [Graf and Therrien, 2007]. This work extends the model’s capability to include thermal energy transport in the unsaturated zone and in the surface water, which is considered a key step in the linkage between the atmospheric and hydrologic systems. Surface heat fluxes from atmospheric inputs are an important source/sink of thermal energy, especially to the surface water system. As such, surface heat fluxes across the land surface were also incorporated into HydroGeoSphere. A complete description of the physical processes and governing flow and solute transport equations that form the basis of HydroGeoSphere can be found in Therrien et al. [2007] and therefore will not be presented here.
The general equation for variably saturated subsurface thermal energy transport following Molson et al. [1992] is given by:
where is the density, is the heat capacity, is the temperature of the bulk subsurface, is the thermal conductivity, is the thermal dispersion term, is the thermal source/sink, is the thermal interactions between the surface and subsurface, and is the external thermal interactions.
Surface-subsurface coupling
The 2-D areal surface flow modules of HydroGeoSphere follow the same conventions for spatial and temporal discretizations as those used by the subsurface modules. The surface flow equation is solved on a 2-D finite-element mesh stacked upon a subsurface grid when solving for both domains (i.e. the x- and y-locations of nodes are the same for each layer of nodes). For superposition, the grid generated for the subsurface domain is mirrored areally for the surface flow nodes, with surface flow node elevations corresponding to the top elevation of the topmost active layer of the subsurface grid. Note that surface flow node elevations may vary substantially to conform with topography. However, the assumptions of small slope inherent in the diffusion-wave equation will not allow for modeling of inertial effects.
The discretized surface equation is coupled with the 3-D subsurface flow equation via superposition (common node approach) or via leakage through a surficial skin layer (dual node approach). For both approaches, fully implicit coupling of the surface and subsurface flow regimes provides an integral view of the movement of water, as opposed to the traditional division of surface and subsurface regimes. Flux across the land surface is, therefore, a natural internal process allowing water to move between the surface and subsurface flow systems as governed by local flow hydrodynamics, instead of using physically artificial boundary conditions at the interface. When the subsurface connection is provided via superposition, HydroGeoSphere adds the surface flow equation terms for the 2-D surface mesh to those of the top layer of subsurface nodes. In that case, the fluid exchange flux, which contains leakance term does not need to be explicitly defined.
Features
The HGS model is a three-dimensional control-volume finite element simulator which is designed to simulate the entire terrestrial portion of the hydrologic cycle. It uses a globally implicit approach to simultaneously solve the 2D diffusive-wave equation and the 3D form of Richards’ equation. HGS also dynamically integrates key components of the hydrologic cycle such as evaporation from bare soil and water bodies, vegetation-dependent transpiration with root uptake, snowmelt and soil freeze/thaw. Features such as macro pores, fractures, and tile drains can either be incorporated discretely or using a dual-porosity, dual permeability formulation. Additionally, HydroGeoSphere has been linked to Weather Research and Forecasting, a mesoscale atmospheric model for fully coupled subsurface, surface, and atmospheric simulations.
Other groundwater models
FEFLOW
MODFLOW
OpenGeoSys
References
External links
Scientific simulation software
Hydrogeology software
Hydrology models
Integrated hydrologic modelling
Earth sciences software | HydroGeoSphere | [
"Biology",
"Environmental_science"
] | 1,662 | [
"Hydrology",
"Environmental modelling",
"Hydrology models",
"Biological models"
] |
12,101,027 | https://en.wikipedia.org/wiki/Holstein%E2%80%93Primakoff%20transformation | In quantum mechanics, the Holstein–Primakoff transformation is a mapping from boson creation and annihilation operators to the spin operators, effectively truncating their infinite-dimensional Fock space to finite-dimensional subspaces.
One important aspect of quantum mechanics is the occurrence of—in general—non-commuting operators which represent observables, quantities that can be measured.
A standard example of a set of such operators are the three components of the angular momentum operators, which are crucial in many quantum systems.
These operators are complicated, and one would like to find a simpler representation, which can be used to generate approximate calculational schemes.
The transformation was developed in 1940 by Theodore Holstein, a graduate student at the time, and Henry Primakoff. This method has found widespread applicability and has been extended in many different directions.
There is a close link to other methods of boson mapping of operator algebras: in particular, the (non-Hermitian) Dyson–Maleev technique, and to a lesser extent the Jordan–Schwinger map. There is, furthermore, a close link to the theory of (generalized) coherent states in Lie algebras.
Description
The basic idea can be illustrated for the basic example of spin operators of quantum mechanics.
For any set of right-handed orthogonal axes, define the components of this vector operator as , and , which are mutually noncommuting, i.e., and its cyclic permutations.
In order to uniquely specify the states of a spin, one may diagonalise any set of commuting operators. Normally one uses the SU(2) Casimir operators and , which leads to
states with the quantum numbers ,
The projection quantum number takes on all the values .
Consider a single particle of spin (i.e., look at a single irreducible representation of SU(2)). Now take the state with maximal projection , the extremal weight state as a vacuum for a set of boson operators, and each subsequent state with lower projection quantum number as a boson excitation of the previous one,
Each additional boson then corresponds to a decrease of in the spin projection. Thus, the spin raising and lowering operators
and , so that , correspond (in the sense detailed below) to the bosonic annihilation and creation operators, respectively.
The precise relations between the operators must be chosen to ensure the correct commutation relations for the spin operators, such that they act on a finite-dimensional space, unlike the original Fock space.
The resulting Holstein–Primakoff transformation can be written as
The transformation is particularly useful in the case where is large, when the square roots can be expanded as Taylor series, to give an expansion in decreasing powers of .
Alternatively to a Taylor expansion there has been recent progress with a resummation of the series that made expressions possible that are polynomial in bosonic operators but still mathematically exact (on the physical subspace). The first method develops a resummation method that is exact for spin , while the latter employs a Newton series (a finite difference) expansion with an identical result, as shown below
While the expression above is not exact for spins higher than 1/2 it is an improvement over the Taylor series. Exact expressions also exist for higher spins and include terms. Much like the result above also for the expressions of higher spins and therefore the resummation is hermitian.
There also exists a non-Hermitian Dyson–Maleev (by Freeman Dyson and S.V. Maleev) variant realization J is related to the above and valid for all spins,
satisfying the same commutation relations and characterized by the same Casimir invariant.
The technique can be further extended to the Witt algebra, which is the centerless Virasoro algebra.
See also
Spin wave
Jordan–Wigner transformation
Jordan–Schwinger transformation
Bogoliubov–Valatin transformation
Klein transformation
References
Quantum mechanics | Holstein–Primakoff transformation | [
"Physics"
] | 801 | [
"Theoretical physics",
"Quantum mechanics"
] |
12,101,061 | https://en.wikipedia.org/wiki/Anil%20Aggrawal%27s%20Internet%20Journal%20of%20Forensic%20Medicine%20and%20Toxicology | Anil Aggrawal's Internet Journal of Forensic Medicine and Toxicology is an online scientific journal covering forensic medicine and toxicology and allied subjects such as criminology, police science, and deviant behavior. It is one of the most widely read and popular peer-reviewed forensic medicine journals in the world. The journal is published semiannually and is indexed by EMBASE, Chemical Abstracts Service, Locatorplus, EBSCO, Indianjournals.com, Scopus and Emerging Sources Citation Index (ESCI) by Clarivate. It was established by Anil Aggrawal (Maulana Azad Medical College, New Delhi) in 2000.
Thematic issues
The journal has produced several thematic issues on forensic entomology edited by Mark Benecke of Germany, on crime scene investigation edited by Daryl Clemens, and on toxicology edited by V.V.Pillay of India.
References
External links
Anil Aggrawal's Internet Journal of Book Reviews (Sister publication)
Academic works about forensics
Open access journals
Academic journals established in 2000
Biannual journals
Toxicology journals
English-language journals
Criminology journals | Anil Aggrawal's Internet Journal of Forensic Medicine and Toxicology | [
"Environmental_science"
] | 234 | [
"Toxicology journals",
"Toxicology"
] |
12,101,596 | https://en.wikipedia.org/wiki/Convolution%20power | In mathematics, the convolution power is the n-fold iteration of the convolution with itself. Thus if is a function on Euclidean space Rd and is a natural number, then the convolution power is defined by
where ∗ denotes the convolution operation of functions on Rd and δ0 is the Dirac delta distribution. This definition makes sense if x is an integrable function (in L1), a rapidly decreasing distribution (in particular, a compactly supported distribution) or is a finite Borel measure.
If x is the distribution function of a random variable on the real line, then the nth convolution power of x gives the distribution function of the sum of n independent random variables with identical distribution x. The central limit theorem states that if x is in L1 and L2 with mean zero and variance σ2, then
where Φ is the cumulative standard normal distribution on the real line. Equivalently, tends weakly to the standard normal distribution.
In some cases, it is possible to define powers x*t for arbitrary real t > 0. If μ is a probability measure, then μ is infinitely divisible provided there exists, for each positive integer n, a probability measure μ1/n such that
That is, a measure is infinitely divisible if it is possible to define all nth roots. Not every probability measure is infinitely divisible, and a characterization of infinitely divisible measures is of central importance in the abstract theory of stochastic processes. Intuitively, a measure should be infinitely divisible provided it has a well-defined "convolution logarithm." The natural candidate for measures having such a logarithm are those of (generalized) Poisson type, given in the form
In fact, the Lévy–Khinchin theorem states that a necessary and sufficient condition for a measure to be infinitely divisible is that it must lie in the closure, with respect to the vague topology, of the class of Poisson measures .
Many applications of the convolution power rely on being able to define the analog of analytic functions as formal power series with powers replaced instead by the convolution power. Thus if is an analytic function, then one would like to be able to define
If x ∈ L1(Rd) or more generally is a finite Borel measure on Rd, then the latter series converges absolutely in norm provided that the norm of x is less than the radius of convergence of the original series defining F(z). In particular, it is possible for such measures to define the convolutional exponential
It is not generally possible to extend this definition to arbitrary distributions, although a class of distributions on which this series still converges in an appropriate weak sense is identified by .
Properties
If x is itself suitably differentiable, then from the properties of convolution, one has
where denotes the derivative operator. Specifically, this holds if x is a compactly supported distribution or lies in the Sobolev space W1,1 to ensure that the derivative is sufficiently regular for the convolution to be well-defined.
Applications
In the configuration random graph, the size distribution of connected components can be expressed via the convolution power of the excess degree distribution ():
Here, is the size distribution for connected components, is the excess degree distribution, and denotes the degree distribution.
As convolution algebras are special cases of Hopf algebras, the convolution power is a special case of the (ordinary) power in a Hopf algebra. In applications to quantum field theory, the convolution exponential, convolution logarithm, and other analytic functions based on the convolution are constructed as formal power series in the elements of the algebra . If, in addition, the algebra is a Banach algebra, then convergence of the series can be determined as above. In the formal setting, familiar identities such as
continue to hold. Moreover, by the permanence of functional relations, they hold at the level of functions, provided all expressions are well-defined in an open set by convergent series.
See also
Convolution
Convolution theorem
Fourier transform
Taylor series
References
.
.
.
.
.
.
.
Functional analysis
Fourier analysis | Convolution power | [
"Mathematics"
] | 882 | [
"Functional analysis",
"Mathematical objects",
"Functions and mappings",
"Mathematical relations"
] |
12,102,117 | https://en.wikipedia.org/wiki/Michael%20Tye%20%28philosopher%29 | Michael Tye (born 1950) is a British philosopher who is currently the Dallas TACA Centennial Professor in Liberal Arts at the University of Texas at Austin. He has made significant contributions to the philosophy of mind.
Education and career
Tye completed his undergraduate education at Oxford University in England, studying first physics and then physics and philosophy. He went on to complete a PhD in philosophy at the State University of New York, Stony Brook. Before moving to Texas, Tye taught at Haverford College in suburban Philadelphia and Temple University in Philadelphia proper. He was also a visiting professor at King's College, London for some ten consecutive years while at Temple and briefly took up a chair at the University of St. Andrews. In 2023, Tye met with the Dalai Lama in Dharamsala at a conference dedicated to the topic of animal consciousness. Besides philosophy of mind, Tye has interests in cognitive science, metaphysics, and philosophical logic, especially problems relating to vagueness.
Tye's third book, Ten Problems of Consciousness (1995), was a selection of the Library of Science Book Club.
Representationalism
In the philosophy of mind, Tye has dedicated much of his work to the development and defense of representationalism. Representationalism is a thesis about the phenomenal, “qualitative” character of conscious experiences. According to Tye, the most basic version of the representationalist thesis holds that “necessarily (visual) experiences that are alike with respect to the qualities they represent are alike phenomenally.”. Tye has argued for representationalism about conscious experience in general on the grounds that it provides the best explanation of the connection between phenomenal and representational features in experience, the "transparent" character of sensory consciousness, and perceptual accuracy conditions.
In his early work on representationalism, Tye defended materialist views about conscious representation and developed an influential account of phenomenal character known as the "PANIC theory". According to the PANIC theory, “phenomenal character is one and the same as Poised Abstract Nonconceptual Intentional Content.” Tye's proposal precludes the possibility that conceptual states such as beliefs are (or could be) phenomenally conscious. Tye later came to reject the PANIC theory in favor of the view that phenomenal character is nothing other than the cluster of properties represented by an experience (as opposed to being a representational content). In his more recent work, Tye retains his commitment to representationalism while rejecting the claim that phenomenally conscious states can be fully characterized in terms of standard materialist features.
Color
Tye endorses the realist view that “colors are physical properties whose natures are discoverable by empirical investigation.” His work on color has broadly examined the extent to which contemporary science can be reconciled with pre-theoretical convictions about the nature of color. Tye affirms what he calls the “commonsense” belief that colors are objective features of surfaces.
Tye has defended his view of color in print against criticism from Ned Block.
Animal consciousness
Tye has authored papers on animal consciousness and pain in animals. He is the author of the book, Tense Bees and Shell-Shocked Crabs: Are Animals Conscious?, published in 2016. The book defends the hypothesis that consciousness extends a considerable way down the phylogenetic scale, focusing on felt pain as a criterion. He states that, in the absence of defeaters, we should prefer the view that animals feel pain if they behave similarly to humans in contexts where we know that humans feel pain. He has reviewed scientific studies and concludes that mammals, birds, reptiles, fish, and arthropods are, in most cases, likely to be conscious.
According to Tye, current evidence suggests that teleost fish feel pain while the evidence for pain in elasmobranchs and certain insects remains inconclusive. Tye has commented that "insects do not react to treatment that would undoubtedly cause severe pain in mammals. So, there is reason to doubt that generally insects feel pain." However, in Chapter 5 of Vagueness And The Evolution Of Consciousness: Through The Looking Glass, Tye favorably considers opposing evidence including cases of apparent pain-behavior in elasmobranchs and insects as well as “striking commonalities in gene pathways in fruit flies and mice, pathways that aid mice in sensing pain and fixing pain thresholds.” In Chapter 11 of Tense Bees and Shell-Shocked Crabs: Are Animals Conscious?, Tye discusses arguments in favor of vegetarianism.
Tense Bees and Shell-Shocked Crabs: Are Animals Conscious? has been reviewed in Metascience and PsycCRITIQUES.
Panpsychism
In his 2021 book, Vagueness And The Evolution Of Consciousness: Through The Looking Glass, Tye abandons an earlier form of physicalism and argues that sensory experience cannot be fully characterized by the resources of standard scientific investigation. On the basis of issues relating to vagueness and the emergence of consciousness, Tye endorses a modified, “panpsychist” form of representationalism. This view holds that fundamental physical particles possess a basic, proto-phenomenal mental property that transfers to representational states when the particles are appropriately arranged. According to his new position, this basic mental property (which Tye refers to as “consciousness*”) is a necessary feature of phenomenally conscious states over and above the representational features described in his previous work.
Tye holds that fundamental physics can only “tell us about the relational/structural properties of matter.” Significantly, these relational/structural properties do not include the intrinsic mental property that he attributes to fundamental particles and conscious states. However, Tye maintains that his proposed property still qualifies as genuinely physical on the grounds that it is “found in things that are unconscious as well as in things that are conscious”, occurs “across all of nature at the most fundamental level”, and obeys “fundamental physical laws”. For this reason, Tye denies that his conversion constitutes an endorsement of anti-physicalism.
Books
The Metaphysics of Mind (1989)
The Imagery Debate (1991)
Ten Problems of Consciousness (1995)
Consciousness, Color, and Content (2000)
Consciousness and Persons (2003)
Consciousness Revisited: Materialism without Phenomenal Concepts (2009)
Tense Bees and Shell-Shocked Crabs: Are Animals Conscious? (2016)
Vagueness And The Evolution Of Consciousness: Through The Looking Glass (2021)
See also
Qualia
Consciousness
Naïve realism
Fred Dretske
Ned Block
David Chalmers
Philosophy of mind
Mind–body problem
References
External links
Michael Tye's personal webpage (includes articles for download).
Michael Tye's Academia.edu page (includes articles for download)
Stanford Encyclopedia of Philosophy entry on Qualia
Interview for Mind and Consciousness
A review of Consciousness, Colour, and Content by Bill Brewer of Oxford University.
Living people
1950 births
20th-century British philosophers
21st-century British philosophers
Animal cognition writers
Animal ethicists
Analytic philosophers
British animal rights scholars
English vegetarianism activists
British consciousness researchers and theorists
Panpsychism
British philosophers of mind
Haverford College faculty
Materialists
Temple University faculty | Michael Tye (philosopher) | [
"Physics"
] | 1,450 | [
"Materialism",
"Matter",
"Materialists"
] |
12,102,352 | https://en.wikipedia.org/wiki/Zeiss-Planetarium%20Jena | The Zeiss-Planetarium in Jena, Germany, is the oldest continuously operating planetarium in the world.
Engineered by German engineer Walther Bauersfeld, the building was opened on 18 July 1926.
The Zeiss-Planetarium is a projection planetarium; the planets and fixed stars are projected onto the inner surface of a white cupola.
It is owned and operated by the Ernst-Abbe-Stiftung.
See also
Zeiss projector
References
External links
Zeiss-Planetarium Jena
Museums in Thuringia
Jena
Glass engineering and science
History of glass
Buildings and structures in Jena
Tourist attractions in Thuringia | Zeiss-Planetarium Jena | [
"Materials_science",
"Engineering"
] | 127 | [
"Glass engineering and science",
"Materials science"
] |
12,102,438 | https://en.wikipedia.org/wiki/Nephrogenic%20systemic%20fibrosis | Nephrogenic systemic fibrosis is a rare syndrome that involves fibrosis of the skin, joints, eyes, and internal organs. NSF is caused by exposure to gadolinium in gadolinium-based MRI contrast agents (GBCAs) in patients with impaired kidney function. Epidemiological studies suggest that the incidence of NSF is unrelated to gender or ethnicity and it is not thought to have a genetic basis. After GBCAs were identified as a cause of the disorder in 2006, and screening and prevention measures put in place, it is now considered rare.
Signs and symptoms
Clinical features of NSF develop within days to months and, in some cases, years following exposure to some GBCAs. The main symptoms are the thickening and hardening of the skin associated with brawny hyperpigmentation, typically presenting in a symmetric fashion. The skin gradually becomes fibrotic and adheres to the underlying fascia. The symptoms initiate distally in the limbs and progress proximally, sometimes involving the trunk. Joint contractures of the fingers, elbows and knees can develop secondary to skin involvement and can severely impair physical function. While skin involvement is on the foreground, the process may involve any organ, e.g., the eye, heart, diaphragm, pleura, pericardium, and kidneys, as well as the lungs and liver.
Causes
NSF is an iatrogenic disease caused by exposure to gadolinium-based contrast agents used in magnetic resonance imaging.
Risk factors
Impaired kidney function reduces the clearance of GBCAs and is the major risk factor for the development of NSF. The etiology or duration of renal failure seems not to be relevant, but NSF risk greatly depends on the residual kidney function. The majority of NSF cases have been identified in patients with stage 5 CKD, but NSF has also developed in patients with stage 4 and 3 CKD, and those with acute kidney injury, even if kidney function subsequently returned to normal following GBCA administration. Thus NSF should be considered as a differential diagnosis in any patient who has been exposed to a GBCA, regardless of the kidney function level.
Three GBCAs have been principally implicated in NSF: gadodiamide, gadopentetate dimeglumine, and gadoversetamide, though cases have been reported with majority of GBCAs on the market. High doses in individual GBCA administrations and high cumulative doses of GBCA over the lifetime of patients with renal dysfunction are associated with increased risk of NSF.
Mechanism
De-chelation of Gd(III) is responsible for the toxicity associated with gadolinium complexes such as GBCAs, and the toxicity appears to be a consequence of Zn2+, Cu2+, and Ca2+ transmetallation in vivo. This hypothesis is supported by acute toxicity experiments, which demonstrate that despite a 50-fold range of LDse values for four Gd(III) complexes, all become lethally toxic when they release precisely the same quantity of Gd(III). It is also supported by subchronic rodent toxicity experiments, which demonstrate a set of gross and microscopic findings similar to those known to be caused by Zn2+ deficiency. Under the transmetallation hypothesis, we can expect that subtle changes in formulation can affect the intrinsic safety of gadolinium complexes, which is indeed observed.
Diagnosis
There is no specific imaging finding for NSF, and the diagnosis is a clinicopathological one, based on presentation and histological findings.
Microscopic pathology
At the microscopic level, NSF shows a proliferation of dermal fibroblasts and dendritic cells, thickened collagen bundles, increased elastic fibers, and deposits of mucin. More recent case reports have described the presence of sclerotic bodies (also known as elastocollagenous balls) in skin biopsies from NSF patients. While not universally present, this finding is believed to be unique to patients exposed to gadolinium, although not necessarily limited to areas involved by NSF.
Differential diagnosis
The differential diagnoses for NSF include diffuse cutaneous or limited cutaneous systemic sclerosis, scleromyxedema, lipodermatosclerosis, scleroedema diabeticorum, graft versus host disease, eosinophilic fasciitis; eosinophilia-myalgia syndrome; porphyria cutanea tarda, and other disorders. The nearly universal absence of facial skin involvement in NSF, presence of yellow plaques on the sclera of the eyes, absence of Raynaud's phenomenon, and other differences in presentation can aid the proper diagnosis. History of exposure to GBCAs would favor NSF as the differential diagnosis.
Prevention
The only known measure for prevention of NSF is the non-use or cautious use of GBCAs in patients with renal impairment, including preferential use of safer, macrocyclic GBCAs. Performing dialysis immediately after the MRI exam is recommended for patients already in dialysis treatment, but there is no evidence for introducing dialysis in non-dialytic patients for prevention of NSF. Screening for impaired kidney function is routinely conducted and has drastically reduced the incidence of NSF.
Treatment
Multiple therapies for NSF have been attempted, with variable clinical improvement. None have been as effective as restoration of kidney function. Restoration of kidney function by treating the underlying disease process, recovery from acute kidney injury (AKI), or performing a kidney transplant can slow or hold the progression of NSF. A few cases of curative kidney transplantation have been reported, and it is appropriate to consider transplantation as treatment.
Epidemiology
NSF affects males and females in approximately equal numbers and has been reported in patients of different ethnic and geographic regions. It most often affects middle-aged individuals, but there are reports of cases occurring from childhood to senescence.
History
This condition was originally termed "nephrogenic fibrosing dermopathy" as initially only skin involvement in patients with impaired kidney function was observed, and later renamed "nephrogenic systemic fibrosis" to better describe its systemic nature. The term "gadolinium-associated systemic fibrosis" has also been proposed to reflect the fact that impaired kidney function is not in itself the cause of NSF.
The first cases of NSF were identified in 1997, but it was first described as an independent disease entity in 2000. In 2006, the link between NSF and gadolinium-based MRI contrast agents was made. As a result, restrictions on use of GBCAs in patients with an estimated glomerular filtration rate (a measure of kidney function) under 60 and especially under 30 mL/min/1.73 m2 have been recommended and NSF is now considered rare.
After several years of controversy, during which up to 100 Danish patients developed gadolinium poisoning after use of the contrast agent Omniscan, the Norwegian medical company Nycomed admitted that they were aware of some dangers from using gadolinium-based agents in their product.
With both Gadopentetic acid (gadopentetate dimegulumine (Magnevist)) and Gadodiamide (Omniscan) the risk was considered to outweigh the benefits and, as a result, the EMA recommended the licence for intravenous gadopentetic acid and Gadodiamide be suspended.
Following a legally binding decision issued by The European Commission and applicable in all EU Member States (Commission decision date: 23/11/2017), Intravenous Magnevist and Omniscan is now no longer authorised for use in Europe. Magnavist is, however, still authorised in Europe as an intra-articular MR contrast medium. The authorised indication for the use of linear chelated media gadobenic acid (also known as gadobenate dimeglumine; MultiHance) and gadoxetic acid (Primovist) has been limited to delayed phase liver imaging only.
References
Further reading
External links
Connective tissue diseases
Nephrology
Element toxicology
Rare diseases | Nephrogenic systemic fibrosis | [
"Chemistry"
] | 1,686 | [
"Biology and pharmacology of chemical elements",
"Element toxicology"
] |
12,102,450 | https://en.wikipedia.org/wiki/Raspberry%20ketone | Raspberry ketone is a naturally occurring phenolic compound that is the primary aroma compound of red raspberries.
Occurrence
Raspberry ketone occurs in a variety of fruits, including raspberries, cranberries, and blackberries. It is detected and released by orchid flowers, e.g. Dendrobium superbum (syn D. anosmum), and several Bulbophyllum species to attract raspberry ketone-responsive male Dacini fruit flies. It is biosynthesized from coumaroyl-CoA. It can be extracted from the fruit, yielding about 1–4 mg per kg of raspberries.
Preparation
Since the natural abundance of raspberry ketone is very low, it is prepared industrially by a variety of methods from chemical intermediates. One of the ways this can be done is through a Claisen-Schmidt condensation followed by catalytic hydrogenation. First, acetone is condensed with 4-hydroxybenzaldehyde to form an α,β-unsaturated ketone. Then the alkene part is reduced to the alkane. This two-step method produces raspberry ketone in 99% yield. There is a less expensive hydrogenation catalyst, nickel boride, which also demonstrates high selectivity towards hydrogenation of the double bond of enone.
Uses
Raspberry ketone is sometimes used in perfumery, in cosmetics, and as a food additive to impart a fruity odor. It is one of the most expensive natural flavor components used in the food industry. The natural compound can cost as much as $20,000 per kg.
Marketing
Although products containing this compound are marketed for weight loss, there is no clinical evidence for this effect in humans. They are called "ketones" because of the ketone (acetone) group at their end, which is shared with ketone bodies.
Safety
Little is known about the long-term safety of raspberry ketone supplements, especially since little research has been done with humans. Toxicological models indicate a potential for cardiotoxic effects, as well as effects on reproduction and development. Furthermore, in many dietary supplements containing raspberry ketones, manufacturers add other ingredients such as caffeine which may have unsafe effects.
In 1965, the US Food and Drug Administration classified raspberry ketone as generally recognized as safe (GRAS) for the small quantities used to flavor foods.
See also
Raspberry ellagitannin
References
Flavors
Food additives
Ketones
Perfume ingredients
Ketone
4-Hydroxyphenyl compounds | Raspberry ketone | [
"Chemistry"
] | 533 | [
"Ketones",
"Functional groups"
] |
12,103,432 | https://en.wikipedia.org/wiki/Regression%20%28medicine%29 | Regression in medicine is the partial or complete reversal of a disease's signs and symptoms.
Clinically, regression generally refers to a decrease in severity of symptoms without completely disappearing. At a later point, symptoms may return. These symptoms are then called recidive.
In cancer, regression refers to a specific decrease in the size or extent of a tumour. In histopathology, histological regression is one or more areas within a tumor in which neoplastic cells have disappeared or decreased in number. In melanomas, this means complete or partial disappearance from areas of the dermis (and occasionally from the epidermis), which have been replaced by fibrosis, accompanied by melanophages, new blood vessels, and a variable degree of inflammation.
References
Epidemiology
Medical terminology | Regression (medicine) | [
"Environmental_science"
] | 166 | [
"Epidemiology",
"Environmental social science"
] |
4,274,087 | https://en.wikipedia.org/wiki/Keystroke%20dynamics | Keystroke dynamics, keystroke biometrics, typing dynamics, or typing biometrics refer to the collection of biometric information generated by key-press-related events that occur when a user types on a keyboard. Use of patterns in key operation to identify operators predates modern computing, and has been proposed as an authentication alternative to passwords and PIN numbers.
Science
The behavioral biometric of keystroke dynamics uses the manner and rhythm in which an individual types characters on a keyboard or keypad. The user's keystroke rhythms are measured to develop a unique biometric template of the user's typing pattern for future authentication. Keystrokes are separated into static and dynamic typing, which are used to help distinguish between authorized and unauthorized users. Vibration information may be used to create a pattern for future use in both identification and authentication tasks.
History
During the late nineteenth century, telegram operators began to develop unique "signatures" that could be identified simply by their tapping rhythm. As late as World War II, the military transmitted messages through Morse Code. Using a methodology called "The Fist of the Sender," military intelligence identified that an individual had a unique way of keying in a message's "dots" and "dashes", creating a rhythm that could help distinguish ally from enemy.
Keyboard dynamics received attention as a potential alternative to short PIN numbers, which were widely used for authentication early in the expansion of networked computing.
Collection and potential use of keystroke dynamics data
The behavioral biometric of keystroke dynamics uses the manner and rhythm in which an individual types characters on a keyboard or keypad. The user's keystroke rhythms are measured to develop a unique biometric template of the user's typing pattern for future authentication. Keystrokes are separated into static and dynamic typing, which are used to help distinguish between authorized and unauthorized users. Vibration information may be used to create a pattern for future use in both identification and authentication tasks.
Keystroke dynamic information could be used to verify or determine the identity of the person producing the keystrokes. The techniques used to do this vary widely in sophistication and range from statistical techniques to artificial intelligence (AI) approaches such as neural networks.
The time to seek and depress a key (seek-time) and the time the key is held down (hold-time) may be characteristic of an individual, regardless of the total speed at which they type. Most people take longer to find or get to specific letters on the keyboard than their average seek-time for all letters. Which letters require more time vary dramatically and consistently for different people. Right-handed people may be statistically faster in getting to keys they hit with their right-hand fingers than with their left-hand fingers. Index fingers may be faster than other fingers, consistent for a user, regardless of their overall speed.
In addition, sequences of letters may have characteristic properties for a user. In English, the use of "the" is very common, and those three letters may be known as a rapid-fire sequence. Common endings, such as "ing", may be entered far faster than the same letters in reverse order ("gni") to the degree that varies consistently by user. This consistency may hold and reveal common sequences of the user's native language even when they are writing entirely in a different language.
Common "errors" may also be quite characteristic of a user. There is a taxonomy of errors, such as the user's most common "substitutions", "reversals", "drop-outs", "double-strikes", "adjacent letter hits", "homonyms" and hold-length-errors (for a shift key held down too short or too long a time). Even without knowing what language the user is working in, these errors may be detected by looking at the rest of the text and what letters the user goes back and replaces.
Authentication versus identification
Keystroke dynamics is part of a larger class of biometrics known as behavioral biometrics, a field in which observed patterns are statistical in nature. Because of this inherent uncertainty, a commonly held belief is that behavioral biometrics are not as reliable as biometrics used for authentication based on physically observable characteristics such as fingerprints or retinal scans or DNA. Behavioral biometrics use a confidence measurement in replacement of the traditional pass/fail measurements. As such, the traditional benchmarks of False Acceptance Rate (FAR) and False Rejection Rates (FRR) no longer have linear relationships.
The benefit to keystroke dynamics (as well as other behavioral biometrics) is that FRR/FAR can be adjusted by changing the acceptance threshold at the individual level. This allows for explicitly defined individual risk mitigation that physical biometric technologies could not achieve.
One of the major problems that keystroke dynamics runs into is that a user's typing varies substantially during a day and between different days and may be affected by any number of external factors.
Because of these variations, any system will make false-positive and false-negative errors. Some successful commercial products have strategies to handle these issues and have proven effective in large-scale use in real-world settings and applications.
Legal and regulatory issues
Use of keylogging software may be in direct and explicit violation of local laws, such as the U.S. Patriot Act, under which such use may constitute wire-tapping.
Patents
P. Nordström, J. Johansson. Security system and method for detecting intrusion in a computerized system. Patent No. 2 069 993, European Patent Office, 2009.
Other uses
Because human beings generate keystroke timings, they are not well correlated with external processes. They are frequently used as a source of hardware-generated random numbers for computer systems.
Mental health symptoms such as depression and anxiety have also been correlated with keystroke timing features.
See also
Fist (telegraphy)
References
Other references
Checco, J. (2003). Keystroke Dynamics & Corporate Security. WSTA Ticker Magazine,
iMagic Software. (vendor web-site May 2006). Notes: Vendor specializing in keystroke authentication for large enterprises.
AdmitOne Security - formerly BioPassword. (vendor web-site home [Web Page]. URL . Notes: Vendor specializing in keystroke dynamics
Garcia, J. (Inventor). (1986). Personal identification apparatus. (USA 4621334). Notes: US Patent Office -
Bender, S and Postley, H. (Inventors) (2007). Key sequence rhythm recognition system and method. (USA 7206938), Notes: US Patent Office -
Joyce, R., & Gupta, G. (1990). Identity authorization based on keystroke latencies. Communications of the ACM, 33(2), 168-176. Notes: Review up through 1990
much cited
Monrose, F. R. M. K., & Wetzel, S. (1999). Password hardening based on keystroke dynamics. Proceedings of the 6th ACM Conference on Computer and Communications Security, 73-82. Notes: Kent Ridge Digital Labs, Singapore
Young, J. R., & Hammon, R. W. (Inventors). (1989). Method and apparatus for verifying an individual's identity. 4805222). Notes: US Patent Office -
Vertical Company LTD. (vendor web-site October 2006). Notes: Vendor specializing in keystroke authentication solutions for government and commercial agencies.
Lopatka, M. & Peetz, M.H. (2009). Vibration Sensitive Keystroke Analysis. Proceedings of the 18th Annual Belgian-Dutch Conference on Machine Learning, 75-80.
Coalfire Systems Compliance Validation Assessment (2007) https://web.archive.org/web/20110707084309/http://www.admitonesecurity.com/admitone_library/AOS_Compliance_Functional_Assessment_by_Coalfire.pdf
Further reading
User interfaces
Biometrics | Keystroke dynamics | [
"Technology"
] | 1,660 | [
"User interfaces",
"Interfaces"
] |
4,274,789 | https://en.wikipedia.org/wiki/The%20Environment%20Trust%20%28Tower%20Hamlets%29 | The Environment Trust was a registered charity and development trust which, from 1979 until its closure in 2008, was based in the London Borough of Tower Hamlets. It aimed to achieve sustainable development by improving the social, economic and physical environment for community benefit.
The Environment Trust helped to establish Fair Finance, a community development financial institution, which offered a range of financial packages to disadvantaged community members in the East End of London.
The Trust researched and developed renewable energy schemes, including solar, wind, biofuels, and tidal energy, and offered educational workshops in schools around themes of biodiversity, nature and gardening. Through organised events, it assisted people in becoming more involved in improving and using their local green spaces. It also worked with partners and communities to try to effect change in local and national government policy on public spaces and biodiversity.
The organisation provided affordable, environmentally sustainable housing through its green homes schemes. It developed a practical approach to building energy efficient homes with low running costs, which were then sold at 70% of their market value.
The organisation also worked to increase the number of quality, affordable workspaces available to local social enterprises, by acquiring land and properties at discounted cost and transforming them into suitable workspace, which were then developed in line with the Green Homes Specification.
See also
Environment Trust for Richmond upon Thames, now Habitats & Heritage
References
1979 establishments in England
2008 disestablishments in England
Charities based in London
Community development organizations
Environmental charities based in the United Kingdom
Environmental organisations based in London
Former organisations based in the London Borough of Tower Hamlets
Housing organisations based in London
Renewable energy organizations
Sustainable development | The Environment Trust (Tower Hamlets) | [
"Engineering"
] | 322 | [
"Renewable energy organizations",
"Energy organizations"
] |
4,275,506 | https://en.wikipedia.org/wiki/Pelmet | A pelmet (also called a "cornice board") is a framework placed above a window, used to conceal curtain fixtures. These can be used decoratively (to hide the curtain rod) and help insulate the window by preventing convection currents. It is similar in appearance to a valance, which performs the same function but is made of fabric. A pelmet can be made of plywood, and may be painted, or fabric covered.
Exterior timber pelmets are a feature of some historic buildings, fitted on the outside of a window. These may be plain or decorative, with complex fretwork in some examples. These may be purely decorative, or serve to conceal an external blind mechanism.
Due to the appearance of a pelmet, the term is often used to describe an extremely short skirt.
References
External links
Architectural elements | Pelmet | [
"Technology",
"Engineering"
] | 173 | [
"Building engineering",
"Architectural elements",
"Components",
"Architecture"
] |
4,275,666 | https://en.wikipedia.org/wiki/Utility%20Radio | The Utility Radio or Wartime Civilian Receiver was a valve domestic radio receiver, manufactured in Great Britain during World War II starting in July 1944. It was designed by G.D. Reynolds of Murphy Radio. Both AC and battery-operated versions were made.
History
When war broke out in 1939, British radio manufacturers devoted their resources to producing a range of military radio equipment required for the armed forces. This resulted in a shortage of consumer radio sets and spare parts, particularly valves, as all production was for the services. The war also prompted a shortage of radio repairmen, as virtually all of them were needed in the services to maintain vital radio and radar equipment. This meant it was very difficult for the average citizen to get a radio repaired, and with very few new sets available, there was a desperate need to overcome the problem.
The government solved this by arranging for over forty radio manufacturers to produce sets to a standard design with as few components as possible consistent with the ability to source them. Earlier, the government had introduced the "Utility" brand to ensure that all clothing, which was rationed, was produced to a reasonable quality standard as, prior to its introduction, a lot of shoddy goods had appeared on the market; the brand was therefore adopted for this wartime radio.
The Utility Set had limited reception on medium wave and lacked a longwave band to simplify the design. The tuning scale listed only BBC stations. After the war a version with LW was made available and modification kits to retrofit existing sets were marketed.
About 175,000 sets were sold, at a price of £12 3s 4d each. The set is sometimes characterized as the British equivalent of the German Volksempfänger "Peoples' Receiver"; however there were dissimilarities. The Volksempfänger were radio sets designed to be inexpensive enough for any German citizen to purchase one but higher quality consumer radios were always available to Germans who could afford to pay higher prices. By contrast, the Utility Set was the only consumer radio receiver available for purchase on the British market for much of the latter part of the war. Starting in June 1942, manufacture of consumer radio receivers in the United States also ceased due to military production needs.
Specifications
The sets used a four-valve superhet circuit with an audio output of 4 watts at 10% total harmonic distortion; they performed as well as many pre-war sets. The valve complement consisted of a triode-hexode frequency mixer, a variable-μ RF pentode IF amplifier and a high slope output pentode. A "Westector" solid-state copper oxide diode was used for demodulation, which saved one valve and allowed use of an available type of pentode for the audio stage. The HT line was derived from a full wave rectifier. All valves were on International Octal sockets apart from the rectifier which was on a British 4-pin base. There were minor variations between set makers; for instance Philips used IF transformers with adjustable ferrite cores (so-called slug tuning) rather than the conventional trimmer capacitors.
Manufacturers
More than 40 manufacturers, such as Pye Ltd. and Marconiphone, made Utility radios. The manufacturer of a particular set was not readily apparent to the general public, although each manufacturer stamped a code letter on the radio to identify themselves to dealers. UK makers often used different designations for the same valve (tube), while octal tubes might be of USA origin. All valves in the Utility radio used standard designations prefixed by BVA (for British Valve Association). They were produced by valve makers such as Mullard, MOV, Cossor, Mazda and Brimar. Dealers, knowing the maker of a set and which valve manufacturer that maker used, could easily deduce which pre-war types these were and make warranty claims on the manufacturer.
References
External links
Technical review by BBC Research Department, 1943
Utility Set(1)
Utility Set(2)
Manufacturers and valve complement
Government Surplus advertisement
Types of radios
Radio electronics
United Kingdom home front during World War II
World War II British electronics
Models of radios | Utility Radio | [
"Engineering"
] | 846 | [
"Radio electronics"
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.