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17,206,404 | https://en.wikipedia.org/wiki/Open%20web%20steel%20joist | In structural engineering, the open web steel joist (OWSJ) is a lightweight steel truss consisting, in the standard form, of parallel chords and a triangulated web system, proportioned to span between bearing points.
The main function of an OWSJ is to provide direct support for roof or floor deck and to transfer the load imposed on the deck to the structural frame i.e. beam and column.
In order to accurately design an OWSJ, engineers consider the joist span between bearing points, joist spacing, slope, live loads, dead loads, collateral loads, seismic loads, wind uplift, deflection criteria and maximum joist depth allowed. Many steel joist manufacturers supply economical load tables in order to allow designers to select the most efficient joist sizes for their projects.
While OWSJs can be adapted to suit a wide variety of architectural applications, the greatest economy will be realized when utilizing standard details, which may vary from one joist manufacturer to another. Some other shapes, in addition to the parallel top and bottom chord, are single slope, double slope, arch, gable and scissor configurations. These shapes may not be available from all joist manufacturers, and are usually supplied at a premium cost that reflects the complexity required.
The manufacture of OWSJ in North America is overseen by the Steel Joist Institute (SJI). The SJI has worked since 1928 to maintain sound engineering practice throughout the industry. As a non-profit organization of active manufacturers, the Institute cooperates with governmental and business agencies to establish steel joist standards. Continuing research and updating are included in this work. Load tables and specifications are published by the SJI in five categories: K-Series, LH-Series, DLH-Series, CJ-Series, and Joist Girders. Load tables are available in both Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD).
History
The first joist in 1923 was a Warren truss type, with top and bottom chords of round bars and a web formed from a single continuous bent bar. Various other types were developed, but problems also followed because each manufacturer had their own design and fabrication standards. Architects, engineers and builders found it difficult to compare rated capacities and to use fully the economies of steel joist construction.
Members of the industry began to organize the institute, and in 1928 the first standard specifications were adopted, followed in 1929 by the first load table. The joists covered by these early standards were later identified as open web steel joists, SJ-Series.
K-Series
Open Web Steel Joists, K-Series, were primarily developed to provide structural support for floors and roofs of buildings. They possess multiple advantages and features which have resulted in their wide use and acceptance throughout the United States and other countries.
K-Series Joists are standardized regarding depths, spans, and load-carrying capacities. There are 63 separate designations in the Load Tables, representing joist depths from through in increments and spans through . Standard K-Series Joists have a end bearing depth so that, regardless of the overall joist depths, the tops of the joists lie in the same plane. Seat depths deeper than can also be specified.
Standard K-Series Joists are designed for simple span uniform loading which results in a parabolic moment diagram for chord forces and a linearly sloped shear diagram for web forces. When non-uniform and/or concentrated loads are encountered the shear and moment diagrams required may be shaped quite differently and may not be covered by the shear and moment design envelopes of a standard K-Series Joist. When conditions such as this arise, a KCS joist may be a good option.
KCS Joists
KCS (K-Series Constant Shear) joists are designed in accordance with the Standard Specification for K-Series Joists.
KCS joist chords are designed for a flat positive moment envelope. The moment capacity is constant at all interior panels. All webs are designed for a vertical shear equal to the specified shear capacity and interior webs will be designed for 100% stress reversal.
LH- and DLH-Series
Longspan (LH) and Deep Longspan (DLH) Steel Joists are relatively light weight shop-manufactured steel trusses used in the direct support of floor or roof slabs or decks between walls, beams, and main structural members.
The LH- and DLH-Series have been designed for the purpose of extending the use of joists to spans and loads in excess of those covered by Open Web Steel Joists, K-Series.
LH-Series Joists have been standardized in depths from through , for spans through .
DLH-Series Joists have been standardized in depths from through , for spans up through .
Longspan and Deep Longspan Steel Joists can be furnished with either underslung or square ends, with parallel chords or with single or double pitched top chords to provide sufficient slope for roof drainage. Square end joists are primarily intended for bottom chord bearing.
The depth of the bearing seat at the ends of underslung LH- and DLH-Series Joists have been established at for chord section number 2 through 17. A bearing seat depth of has been established for the DLH Series chord section number 18 through 25.
CJ-Series
Open Web Composite Steel Joists, CJ-Series, were developed to provide structural support for floors and roofs which incorporate an overlying concrete slab while also allowing the steel joist and slab to act together as an integral unit after the concrete has adequately cured.
The CJ-Series Joists are capable of supporting larger floor or roof loadings due to the attachment of the concrete slab to the top chord of the composite joist. Shear connection between the concrete slab and steel joist is typically made by the welding of shear studs through the steel deck to the underlying CJ-Series Composite Steel Joist.
Joist Girders
Joist Girders are open web steel trusses used as primary framing members. They are designed as simple spans supporting equally spaced concentrated loads for a floor or roof system. These concentrated loads are considered to act at the panel points of the Joist Girders.
These members have been standardized for depths from , and spans to .
The standard depth at the bearing ends has been established at for all Joist Girders. Joist Girders are usually attached to the columns by bolting with two diameter A325 bolts.
See also
I-beam
Structural steel
References
Steel Joist Institute
Structural engineering
Structural steel | Open web steel joist | Engineering | 1,349 |
37,018,394 | https://en.wikipedia.org/wiki/Johannes%20Groenland | Johannes Groenland (also spelled Grönland and called "Jean Groenland," 1824–1891) was a German botanist, horticulturist, and microscopist.
Early life
He was born on 8 April 1824 in Altona, a borough of Hamburg that was part of the Duchy of Holstein at that time. He was the son of Johann Friedrich Grönland, a German organist and music teacher.
Career
Early career, First Schleswig War
Groenland was trained in pharmacology in his youth and served as a pharmacist in Altona, Hamburg, and Jena in his early 20s. In 1849 he joined the Schleswig-Holstein army to fight in the First Schleswig War.
Life in Paris
After the war, Groenland moved to Paris to work as an assistant to Louis de Vilmorin, a French biologist and horticulturist who was also a member of the family firm Vilmorin-Andrieux. While working for Vilmorin, Groenland worked with Theodor Rümpler to prepare the German edition of Les fleurs de pleine terre (Vilmorin's illustrierte Blumengärtnerei).
Groenland spent almost twenty years living in Paris working as a botanical researcher and horticulturist. He was a founding member of the Société botanique de France and was known for his work creating hybrids by crossing Triticum vulgare with various species of Aegilops. His botanical research also focused on liverworts, seagrasses, and the genus Drosera; and he served as the editor of the journal Revue horticole. In addition to his research and writing, Groenland developed skills in preparing botanical slides while living in Paris. He ran his own microscopist business from his residence at 13 Rue des Boulangers, and along with Marie Maxime Cornu and Gabriel Rivet, he wrote Des préparations microscopiques tirées du regne végétal, which was commonly used in the 19th century as a textbook on the preparation of microscope slides.
Move to Dahme
Groenland and his wife left Paris in May 1871 after the conclusion of the Franco-Prussian War. They settled in Dahme, Germany, where he worked as a botanist and professor of natural sciences at the Agricultural and Agricultural Chemistry Research Station until his death on 13 February 1891. At that time, he was also an active and important member of the Botanischer Verein der Provinz Brandenburg.
Legacy
The genus Groenlandia in the family Potamogetonaceae (pondweed) is named in his honor.
Selected works
Mémoire sur la germination de quelques hépatiques (1854)
Note sur l’Holcus setiger (1855)
Note sur les organs glanduleux du genre Drosera (1856)
Note sur l’hybridation du genre Aegilops (1857)
Note sur les hybrids du genre Aegilops (1862)
Histoire naturelle ilustrée: végétaux (1870)
Des préparations microscopiques tirées du regne végétal (1872)
Vilmorin's illustrierte Blumengärtnerei (1872-5)
References
1824 births
1891 deaths
People from Altona, Hamburg
People from the Duchy of Holstein
19th-century German botanists
German horticulturists
Microscopists
Scientists from Hamburg | Johannes Groenland | Chemistry | 714 |
35,262,599 | https://en.wikipedia.org/wiki/Grigorii%20Fikhtengol%27ts | Grigorii Mikhailovich Fikhtengol'ts (, ; 8 June 1888 – 26 June 1959) was a Soviet mathematician working on real analysis and functional analysis. Fikhtengol'ts was one of the founders of the Leningrad school of real analysis.
He was born in Odessa, Russian Empire in 1888, and graduated Odessa University in 1911.
He authored a three-volume textbook titled "A Course of Differential and Integral Calculus". The textbook covers mathematical analysis of functions of one real variable, functions of many real variables, and complex functions. Due to the depth and precision of the material's presentation, the book holds a classical position in the mathematical literature. It has been translated into several languages, including German, Polish, Chinese, Vietnamese, and Persian. However, no English translation has been completed yet.
Fikhtengol'ts's books on analysis are widely used in Middle and Eastern European, as well as Chinese universities, due to their exceptionally detailed and well-organized presentation of material on mathematical analysis. For unknown reasons, these books have not gained the same level of fame in universities in other parts of the world.
He was an Invited Speaker of the ICM in 1924 in Toronto.
Leonid Kantorovich and Isidor Natanson were among his students.
Books
References
External links
Grigorii Mikhailovich Fichtenholz
Soviet mathematicians
Mathematical analysts
1888 births
1959 deaths
Odesa University alumni | Grigorii Fikhtengol'ts | Mathematics | 289 |
14,876,163 | https://en.wikipedia.org/wiki/Thymic%20stromal%20lymphopoietin | Thymic stromal lymphopoietin (TSLP) is an interleukin (IL)-2-like cytokine, alarmin, and growth factor involved in numerous physiological and pathological processes, primarily those of the immune system. It shares a common ancestor with IL-7.
Originally appreciated for its role in immune cell proliferation and development, and then for its pivotal role in type 2 immune responses, TSLP is now known to be involved in other types of immune responses, autoimmune disease, and certain cancers.
Gene ontology
TSLP production has been observed in numerous species, including humans and mice.
In humans, TSLP is encoded by the TSLP gene. Alternative splicing of TSLP results in two transcript variants, a long form (lfTSLP, or just TSLP) consisting of 159 amino acid residues, and a short form (sfTSLP) consisting of 63 amino acid residues. These variants use different initiation methionine codons and share a carboxy terminus.
sfTSLP
sfTSLP mRNA is constitutively expressed in normal human bronchial epithelial cells (NHBE), normal human lung fibroblasts (NHLF), and bronchial smooth muscle cells (BSMC). sfTSLP mRNA expression is not significantly upregulated by inflammation.
TSLP
TSLP mRNA is not constitutively expressed in NHBE and has a low level of constitutive expression in NHLF and BSMC. TSLP mRNA expression is upregulated by certain Toll-like receptor (TLR) ligands such as flagellin and poly(I:C), but not by lipopolysaccharide (LPS) or macrophage-activating lipopeptide 2 (MALP-2).
Discovery
As the name suggests, TSLP was initially discovered as a growth factor derived from the supernatant of a mouse thymic stromal cell line that was found to promote the survival and proliferation of B lymphocytes.
Function
TSLP was initially observed to have both pro-inflammatory and anti-inflammatory activity. It is now clear that this seemingly ambivalent action can actually be divided between the two transcript variants, with TSLP being pro-inflammatory and sfTSLP being anti-inflammatory.
sfTSLP
sfTSLP inhalation prevents airway epithelial barrier disruption caused by the inhalation of house dust mite (HDM) antigens in mice who had been sensitised to HDM, an asthma-like model. Similarly, sfTSLP reduces the severity of dextran sulphate sodium (DSS)-induced colitis in mice, a model of inflammatory bowel disease (IBD), and prevents endotoxic shock and sepsis resulting from bacterial infections.
Signalling
A receptor for sfTSLP has not been discovered. It is not known whether sfTSLP also signals via the TSLP receptor complex.
TSLP
Epithelium defense
TSLP's pivotal role in initiating immune responses begins with its release by epithelial or stromal cells of the lungs, skin, or gastrointestinal tract as an alarmin following mechanical cell injury, pattern recognition receptor (PRR) and protease-activated receptor (PAR) activation, stimulation by certain cytokines, chemical irritation, or infection.
When local mast cells bind an allergen, they produce TSLP indirectly by releasing tryptase in an FcεRI-dependent manner, activating PARs on epithelial cells and causing them to release TSLP. Unlike IL-33, a similarly acting alarmin, TSLP is usually not constitutively expressed and must be upregulated by transcription factors such as nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) or activator protein (AP)1 following insult.
Type 2 immune responses
Local dendritic cells (DCs) are among the most important targets of TSPL, as they, among other antigen presenting cells (APCs), allow the immune system to mount adaptive responses. TSLP signalling grants DCs the exact phenotype needed to prime naive CD4+ T cells into TH2 pro-inflammatory cells, or producing type 2 cytokines, namely by upregulating OX40L, CD80, and CD86. TSLP-stimulated DCs that migrate into draining lymph nodes can prime CD4+ T cells into follicular helper T (TFH) cells, which in turn can promote immunoglobulin (Ig)G and E production by resident B lymphocytes, thus initiating type 2 immune responses. TH2 can also facilitate B cell class switching towards IgE.
Type 1 and 3 immune responses
As mentioned, TSLP serves as an alarmin following TLR binding by certain pathogen-associated molecular patterns (PAMPs), including viral and bacterial ones, rather than just irritation by allergens. Thus, TSLP also plays an early role in the initiation of type 1 and 3 immune responses to pathogens. This activity has thus far been best described in the respiratory mucosa.
TSLP-activated CD11b+ DCs can promote the proliferation and long-term survival of CD8+ cytotoxic T cells, promoting the development of lasting adaptive cellular immunity. Analogously, TSLP-activated CD11c+ cells are essential for the development of IgA antibodies following pneumococcal infection. TSLP also holds considerable promise as a novel vaccine adjuvant and anti-cancer immunotherapy due to its broad and potent alarmin functionality, as is evidenced by numerous animal studies.
Germinal centre formation
Germinal centres (GCs) are microstructures that form in secondary lymphoid organs during immune responses. GCs are the sites of the clonal expansion of B lymphocytes and the affinity maturation of their antibodies, thus allowing the immune system to generate antibodies with a high affinity for antigens. TSLP may play an important role in the formation of GCs, as the depletion of TSPLR in CD4+ T cells prevented their formation in mice, as well as the generation of IgG1.
Signalling
TSLP signals through a heterodimeric receptor complex composed of the TSLP receptor (TSLPR) and the IL-7Rα chain. Upon binding, Janus kinase (JAK)1 and 2 are activated, leading to the activation of signal transducer and activator of transcription (STAT)5A and 5B and, to a lesser extent, STAT1 and 3. These transcription factors upregulate pro-inflammatory cytokines such as IL-4, 5, 9, and 13.
Disease
TSLP expression is linked to many disease states including asthma, inflammatory arthritis, atopic dermatitis, eczema, eosinophilic esophagitis and other allergic states. The factors inducing the activation of TSLP release are not clearly defined.
Asthma
Expression of TSLP is enhanced under asthma-like conditions (aka Airway HyperResponsiveness or AHR model in the mouse), conditioning APCs in order to orient the differentiation of T cells coming into the lungs towards a TH2 profile (T helper 2 pathway). The TH2 cells then release factors promoting an inflammatory reaction following the repeated contact with a specific antigen in the airways.
Atopic dermatitis
TSLP-activated Langerhans cells of the epidermis induce the production of pro-inflammatory cytokines like TNF-alpha by T cells potentially causing atopic dermatitis. It is thought that by understanding the mechanism of TSLP production and those potential substances that block the production, one may be able to prevent or treat conditions of asthma and/or eczema.
Therapeutic targeting
The TSLP signaling axis is an attractive therapeutic target. Amgen's Tezepelumab, a monoclonal antibody which blocks TSLP, is currently approved for the treatment of severe asthma. Fusion proteins consisting of TSLPR and IL-7Rα which can trap TSLP with excellent affinity have also been designed. Additional approaches towards TSLP/TSLPR inhibition include peptides derived from the TSLP:TSLPR interface, natural products and computational fragment-based screening.
References
External links
Cytokines | Thymic stromal lymphopoietin | Chemistry | 1,744 |
75,771,425 | https://en.wikipedia.org/wiki/Christoph%20Merten | Christoph Merten (born 1976) is a German bio-engineer and entrepreneur; currently professor at EPFL (École Polytechnique Fédérale de Lausanne). He is an adjunct scientist at the Ludwig Institute for Cancer Research in Lausanne. His research focuses on developing biomedical microfluidics technologies for drug discovery, diagnostics, and personalized therapy in cancer research.
Career
Christoph studied biochemistry and organic chemistry at the Goethe University Frankfurt, Germany. He did his PhD at the Paul Ehrlich Institute in Langen, Germany before having a first postdoctoral research position at the Medical Research Council, Laboratory for Molecular Biology, in Cambridge, UK.
In 2005, he started a second postdoctoral appointment at the Institut de science et d'ingénierie supramoléculaires (ISIS) in Strasbourg, France. He focused on droplet-based microfluidics for cellular assays and started his research group in 2007. From 2010 to 2019, he served as a group leader at the European Molecular Biology Laboratory in Heidelberg, where he established high-throughput droplet-based microfluidic screening platforms.
In 2019, he was named associate professor of bioengineering at EPFL and currently leads the laboratory for biomedical microfluidics (LBMM) within the School of Engineering. He also holds an adjunct scientist position at the Ludwig Institute for Cancer Research's Lausanne branch.
Entrepreneurship
In 2017 he became the scientific founder of Velabs Therapeutics, a microfluidic antibody discovery company now operating as Veraxa Biotech. He is also leading the TheraMe! consortium, developing microfluidic technologies for personalized cancer treatment. This work resulted in the foundation of the EPFL-based Startup TheraMe! in 2023.
Research
His laboratory currently uses droplet-based approaches to address questions related to personalized medicine, biological screening assays, and genomics. In the context of cancer therapy, this work has allowed cost-efficient screening of numerous drug combinations on tumor samples issued from patient biopsies, enabling rapid determination of personalized treatment regimens for cancer patients.
Selected publications
References
External links
Living people
Goethe University Frankfurt alumni
Academic staff of the École Polytechnique Fédérale de Lausanne
21st-century German scientists
Bioengineers
Year of birth missing (living people) | Christoph Merten | Engineering,Biology | 468 |
56,642,366 | https://en.wikipedia.org/wiki/Ellen%20Jorgensen | Ellen D. Jorgensen (born 2 June 1955) is a New York-based molecular biologist and serial entrepreneur. In addition to her long career in the biotechnology industry she is also credited with playing a leading role in promoting the do-it-yourself biology movement where she has worked to increase scientific literacy in the general population, particularly in the fields of molecular and synthetic biology. She is a co-founder of both non-profit (Biotech Without Borders and Genspace. ) and for-profit (Aanika Biosciences) biotechnology-based companies. In 2017, Ellen Jorgensen was named one of the Most Creative Leaders in Business by Fast Company. Her current focus is on combating climate change through her role as Vice President of Biotechnology at CarbonBridge, a biotech startup that uses bacteria to remove environmental methane and create liquid fuel.
Education and career
Ellen Jorgensen graduated from New York University (NYU) in 1977 with a B.A. in Biology. She then went on to earn both her MA and MPhil in Biological Sciences from Columbia University in 1979 and 1981, respectively. Jorgensen returned to NYU where she obtained her Ph.D. in Cell and Molecular Biology in 1987 from the Sackler Institute. She later went to SUNY Downstate as a post-doc to continue research in protein structure and function. Jorgensen has served as adjunct faculty at The Cooper Union in New York City, New York Medical College and at the School of Visual Arts.
Jorgensen devoted many years of her career to various positions at both nonprofit and for-profit companies within the biotechnology sector. She spent eight years, from 2001 to 2009, as the Director of Biomarker Discovery and Development at Vector Research, researching early biomarkers of tobacco-related lung disease. In 2009, she co-founded the community biohacker space, Genspace where she developed innovative programming such as the Biorocket internships for underserved New York City high school students and classes in genetic engineering for the general public. Under her leadership Genspace provided low-cost lab space for biotech entrepreneurs. Opentrons and Curieco both used the Genspace pre-incubator space to launch successful companies. In 2017, Jorgensen founded Biotech Without Borders, a second nonprofit community biotechnology lab where she continues to serve on the board of directors.
In 2009, Ellen Jorgensen co-founded Genspace, the first nonprofit community biotech lab. In 2010, Jorgensen initiated Genspace's curriculum of informal science education, leading to the company being named one the World's Top 10 Innovative Companies in Education. The goal of Genspace is to increase scientific literacy in the general public by providing classes and workshops, as well as a space for community members to get involved in a biotechnology laboratory. In March 2017, Ellen Jorgensen stepped down from her role as executive director to found Biotech Without Borders and was replaced by Genspace co-founder, Daniel Grushkin. Jorgensen became president emeritus.
While Genspace was created with the goal of making scientific literacy more accessible, the organization was met with criticism by those that felt that hands-on science should be left to the professionals. Despite this criticism, Genspace has continued on, along with a larger community of hacker spaces opening worldwide, fostering an open environment of scientific collaboration and learning between amateurs and professionals.
Genspace is located in Brooklyn, New York. The lab follows Biosafety Level 1 restrictions. Different membership tiers are offered providing access to events, classes, lab access, participation to community projects, and more. In the spring of 2018, community projects will be offered in the fields of mycoremediation, open plant collaboration, and optogenetics.
Accolades
World's Top 10 Innovative Companies in Education (Fast Company, 2014)
Maker Space of the Year (Brooklyn Innovation Awards, 2016 & 2017)
Biotech Without Borders
In 2017, Ellen Jorgensen stepped down from her leadership role at Genspace in order to found Biotech Without Borders, where she now acts as President. Biotech Without Borders is a Brooklyn, New York based nonprofit public charity dedicated to enabling communities underrepresented in the biotechnology field to gain hands-on biotech lab experience. Biotech Without Borders focuses on providing a Biosafety Level 2 lab space, distributing biotech resources to labs worldwide, and engaging the public through hands-on lab classes, workshops, and events. It is the first Biosafety Level 2 lab open for public projects. Compared to Genspace, Biotech Without Borders seeks to facilitate engagement with more authentic high-level science.
Selected publications
Albino, Anthony; Huang, Xuan; Jorgensen, Ellen; Gietl, Diana; Traganos, Frank; Darzynkiewicz, Zbigniew (2006-07-01). "Induction of DNA double-strand breaks in A549 and normal human pulmonary epithelial cells by cigarette smoke is mediated by free radicals". International Journal of Oncology. 28: 1491–505. doi:10.3892/ijo.28.6.1491.
Albino, Anthony; Huang, X; Jorgensen, Ellen; Yang, J; Gietl, D; Traganos, F; Darzynkiewicz, Zbigniew (2004-09-01). "Induction of H2AX Phosphorylation in Pulmonary Cells by Tobacco Smoke: A New Assay for Carcinogens". Cell Cycle. 3: 1062–8. doi:10.4161/cc.3.8.988.
Albino, Anthony; Jorgensen, Ellen; Rainey, Patrick; Gillman, Ivan; Jeffrey Clark, T; Gietl, Diana; Zhao, Hong; Traganos, Frank; Darzynkiewicz, Zbigniew (2009-08-01). "gammaH2AX: A potential DNA damage response biomarker for assessing toxicological risk of tobacco products". Mutation research. 678: 43–52. doi:10.1016/j.mrgentox.2009.06.009.
F. Klement, John; B Moorefield, M; Jorgensen, Ellen; E. Brown, Jeanne; Risman, Steven; T. McAllister, William (1990-10-01). "Discrimination between bacteriophage T3 and T7 promoters by the T3 and T7 RNA polymerases depends primarily upon a three base-pair region located 10 to 12 base-pairs upstream from the start site". Journal of molecular biology. 215: 21–9. doi:10.1016/S0022-2836(05)80091-9.
Jorgensen, Ellen; Bhagwat, Dileep (1998-06-01). "Development of dissolution tests for oral extended-release products". Pharmaceutical Science & Technology Today. 1: 128–135. doi:10.1016/S1461-5347(98)00029-7.
Jorgensen, Ellen (1985-09-01). "Partial nucleotide sequence op newcastle disease virus HN gene". Virus Research - VIRUS RES. 3. doi:10.1016/0168-1702(85)90360-0.
Jorgensen, Ellen; Dozmorov, Igor; B Frank, Mark; Centola, Michael; Albino, Anthony (2004-10-01). "Global Gene Expression Analysis of Human Bronchial Epithelial Cells Treated with Tobacco Condensates". Cell Cycle. 3: 1154–68. doi:10.4161/cc.3.9.1078.
Jorgensen, Ellen; Grushkin, Daniel (2011-04-01). "Engage with, don't fear, community labs". Nature medicine. 17: 411. doi:10.1038/nm0411-411.
Jorgensen, Ellen; L. Collins, Peter; T. Lomedico, Peter (1987-02-01). "Cloning and nucleotide sequence of newcastle disease virus hemagglutinin-neuraminidase mRNA: Identification of a putative sialic acid binding site". Virology. 156: 12–24. doi:10.1016/0042-6822(87)90431-4.
Jorgensen, Ellen; Stinson, Andy; Shan, Lin; Yang, Jin; Gietl, Diana; Albino, Anthony (2008-02-01). "Cigarette smoke induces endoplasmic reticulum stress and the unfolded protein response in normal and malignant human lung cells". BMC cancer. 8: 229. doi:10.1186/1471-2407-8-229.
Jorgensen, Ellen; Zhao, Hong; Traganos, Frank; Albino, Anthony; Darzynkiewicz, Zbigniew (2010-06-01). "DNA damage response induced by exposure of human lung adenocarcinoma cells to smoke from tobacco- and nicotine-free cigarettes". Cell Cycle. 9: 2170–6. doi:10.4161/cc.9.11.11842.
Schäffner, Anton; Jorgensen, Ellen; T. McAllister, William; R. Hartmann, Guido (1987-12-01). "Specific labelling of the active site of T7 RNA polymerase". Nucleic Acids Research. 15: 8773–81. doi:10.1093/nar/15.21.8773.
Tanaka, Toshiki; Huang, Xuan; Jorgensen, Ellen; Gietl, Diana; Traganos, Frank; Darzynkiewicz, Zbigniew; Albino, Anthony (2007-02-01). "ATM activation accompanies histone H2AX phosphorylation in A549 cells upon exposure to tobacco smoke". BMC cell biology. 8: 26. doi:10.1186/1471-2121-8-26.
Zhao, Hong; Albino, Anthony; Jorgensen, Ellen; Traganos, Frank; Darzynkiewicz, Zbigniew (2009-10-01). "DNA Damage Response Induced by Tobacco Smoke in Normal Human Bronchial Epithelial and A549 Pulmonary Adenocarcinoma Cells Assessed by Laser Scanning Cytometry". Cytometry. Part A : the journal of the International Society for Analytical Cytology. 75: 840–7. doi:10.1002/cyto.a.20778.
Zhao, Hong; Yang, Jin; Shan, Lin; Jorgensen, Ellen (2011-12-31). "Measuring the Impact of Cigarette Smoke on the UPR". Methods in enzymology. 489: 147–64. doi:10.1016/B978-0-12-385116-1.00009-1.
References
External links
1955 births
Living people
American molecular biologists
American women scientists
Women founders
Biotechnologists
Biotechnology advocacy
New York University alumni
Columbia University alumni
Women biotechnologists
21st-century American women
Cooper Union faculty | Ellen Jorgensen | Engineering,Biology | 2,326 |
75,036,351 | https://en.wikipedia.org/wiki/T%20Puppis | The Bayer designations T Puppis and t Puppis are distinct and refer to two different stars in the constellation Puppis:
T Puppis (HD 63640, TYC 7649-108-1, HIP 38074, HR 3041, 189 G. Puppis), a non-variable star, although T Puppis is a variable star designation
t Puppis (HR 2619, HD 52092, HIP 33558, TYC 7097-2515-1)
Puppis, t
Puppis | T Puppis | Astronomy | 109 |
1,943,968 | https://en.wikipedia.org/wiki/Cativa%20process | The Cativa process is a method for the production of acetic acid by the carbonylation of methanol. The technology, which is similar to the Monsanto process, was developed by BP Chemicals and is under license by BP Plc. The process is based on an iridium-containing catalyst, such as the complex [Ir(CO)2I2]− (1).
The Cativa and Monsanto processes are sufficiently similar that they can use the same chemical plant. Initial studies by Monsanto had shown iridium to be less active than rhodium for the carbonylation of methanol. Subsequent research, however, showed that the iridium catalyst could be promoted by ruthenium, and this combination leads to a catalyst that is superior to the rhodium-based systems. The switch from rhodium to iridium also allows the use of less water in the reaction mixture. This change reduces the number of drying columns necessary, decreases formation of by-products, such as propionic acid, and suppresses the water gas shift reaction.
The catalytic cycle for the Cativa process, shown above, begins with the reaction of methyl iodide with the square planar active catalyst species (1) to form the octahedral iridium(III) species (2), the fac-isomer of [Ir(CO)2(CH3)I3]−. This oxidative addition reaction involves the formal insertion of the iridium(I) centre into the carbon-iodine bond of methyl iodide. After ligand exchange (iodide for carbon monoxide), the migratory insertion of carbon monoxide into the iridium-carbon bond, step (3) to (4), results in the formation of a square pyramidal species with a bound acetyl ligand. The active catalyst species (1) is regenerated by the reductive elimination of acetyl iodide from (4), a de-insertion reaction. The acetyl iodide is hydrolysed to produce the acetic acid product, in the process generating hydroiodic acid which is in turn used to convert the starting material (methanol) to the methyl iodide used in the first step.
References
Organometallic chemistry
Industrial processes
Catalysis
Organoiridium compounds
BP | Cativa process | Chemistry | 481 |
48,480,765 | https://en.wikipedia.org/wiki/Kepler-24b | Kepler-24b is an exoplanet orbiting the star Kepler-24, located in the constellation Lyra. It was discovered by the Kepler telescope in January 2012. It orbits its parent star at only 0.08 astronomical units away, and at its distance it completes an orbit once every 8.145 days.
References
Exoplanets discovered by the Kepler space telescope
Exoplanets discovered in 2012
Transiting exoplanets
Kepler-24
Lyra | Kepler-24b | Astronomy | 95 |
76,785,918 | https://en.wikipedia.org/wiki/Erminia%20Calabrese | Erminia Calabrese, FLSW, is a Professor of Astronomy and the Director of Research at Cardiff University School of Physics and Astronomy. She works in observational cosmology using the cosmic microwave background radiation to understand the origins and evolution of the universe. In 2024 she became a Fellow of the Learned Society of Wales, and in 2022 she was awarded the Institute of Physics Fred Hoyle medal and the Learned Society of Wales Dillwyn medal.
Early life and education
Calabrese was born in Benevento, Italy and grew up in a small town in the Apennines, Cerreto Sannita. She left to attend the Sapienza University of Rome and graduated in 2006 with a degree in Physics and Astrophysics. She stayed at the Sapienza University of Rome for her postgraduate studies, where she first earned a Masters degree in Astronomy and Astrophysics in 2008 and then went on to complete a PhD in Astronomy in 2012.
Research and career
Calabrese moved to the Oxford Astrophysics department in 2012, for a Research Associate position in cosmology, where she was advised by astrophysicist Joanna Dunkley. Calabrese went on to be a Beecroft Fellow at the University of Oxford from 2014 to 2015 before moving on to become a Lyman Spitzer Jr. Fellow at Princeton University from 2015 to 2016. In 2017 she became a STFC (Science and Technologies Facilities Council) Ernest Rutherford Fellow at the University of Oxford before moving to Cardiff in order to establish a cosmology group at Cardiff University. She started as a Lecturer at Cardiff University in 2017 and was promoted to Professor in 2019. As of 2024, Calabrese is the Director of Research for the School of Physics and Astronomy at Cardiff University.
Calabrese’s research combines theoretical work with statistical data analysis to answer fundamental questions about the Universe. As a Scientist of the Planck mission and a science member of the Atacama Cosmology Telescope she led work on characterising multi-frequency CMB microwave data, on combining data from satellite and ground-based experiments, and on extracting the underlying primordial CMB signal carrying the imprint of the physics of the early Universe, leading to state-of-the-art constraints on neutrino physics, inflation, dark matter and dark energy physics. Calabrese and her cosmology team are now exploring new physics signatures in CMB polarisation with future observations from the Simons Observatory and the proposed, Japanese-led LiteBIRD mission. Calabrese is also a member of the LSST Dark Energy Science Collaboration, and a member of the Euclid Collaboration, looking at how to combine low-redshift data with the CMB. She has been featured on several podcasts and shows explaining her research, including BBC Sky at Night Magazine, Physics World Weekly, Radio3 Scienza and the BBC Science Café.
Awards and honours
2024 Learned Society of Wales Fellowship.
2023 UK Space Agency award for LiteBIRD:UK.
2022 UKRI/STFC awards for SO:UK
2022 Institute of Physics Fred Hoyle Medal and Prize, Learned Society of Wales Dillwyn Medal and Prize for STEMM.
2021 H2020 Marie Sklodowska-Curie Actions Research and Innovation Staff Exchange (RISE) consortium grant
2019 European Research Council Starting Grant.
2019 Giuseppe and Vanna Cocconi Prize for the Planck Team.
2018 Gruber prize in cosmology as a member of the Planck team.
2018 Royal Astronomical Society Group Achievement Award for the Planck Team.
2018 Marcel Grossman Award to the Planck scientific collaboration.
2016 STFC Ernest Rutherford Fellowship
2012 Junior Research Fellowship (non-stipendiary), Wolfson College, Oxford.
2011 Tito Maiani prize for thesis in physics.
References
21st-century Italian astronomers
Astronomers
People associated with Cardiff University
1984 births
Living people
21st-century Italian women scientists | Erminia Calabrese | Astronomy | 800 |
30,958,981 | https://en.wikipedia.org/wiki/History%20of%20GLONASS | The satellite navigation system GLONASS was conceived in the late 1960s, and formal requirements were completed in 1970. The government of the Soviet Union made a decision to develop the system in 1976. Design work was carried out by specialists led by Vladimir Cheremisin at NPO PM in Krasnoyarsk-26. The first launch took place in 1982. Until its dissolution in 1991, the Soviet Union launched 43 GLONASS-related satellites. Work on the system was continued by the Russian Federation which brought it its full operational capability in 1995. In the following years, the system fell into disrepair due to the economic crisis in the country and diminished space funding. Starting from 2000, the government under President Vladimir Putin made the restoration of GLONASS a top priority; its funding was doubled and after a lull of several years, launches were restarted again. In 2003, a new satellite design, GLONASS-M, was introduced. By early 2011, GLONASS had 22 operational satellites, two short of the required constellation of 24 to provide global coverage. The latest and significantly improved satellite type, GLONASS-K, was launched in February 2011.
1970–1979: Inception and design
The first satellite-based radio navigation system developed in the Soviet Union was Tsiklon, which had the purpose of providing ballistic missile submarines a method for accurate positioning. 31 Tsiklon satellites were launched between 1967 and 1978. The main problem with the system was that, although highly accurate for stationary or slow-moving ships, it required several hours of observation by the receiving station to fix a position, making it unusable for many navigation purposes and for the guidance of the new generation of ballistic missiles.
From 1968 to 1969, the research institutes of the Ministry of Defence, Academy of Sciences, and Soviet Navy cooperated to develop a single system for navigation of their air, land, sea, and space forces. The requirements of such a system were formulated in a document completed in 1970. Six years later, in December 1976, a plan for developing the system was accepted by the Central Committee of the CPSU and of the Council of Ministers of the USSR in a decree entitled "On Deployment of the Unified Space Navigation System GLONASS."
The task of designing GLONASS was given to a group of young specialists at NPO PM in the city of Krasnoyarsk-26 (today called Zheleznogorsk). Under the leadership of the Vladimir Cheremisin, they developed different proposals, from which the institute's director Grigory Chernyavsky selected the final one. The work was completed in the late 1970s; the system would consist of 24 satellites operating at an altitude of 20,000 km in medium circular orbit. It would be able to promptly fix the receiving station's position based on signals from 4 satellites, and also reveal the object's speed and direction. The satellites would be launched 3 at a time on the heavy-lift Proton rocket. Due to the large number of satellites needed for the program, NPO PM delegated the manufacturing of the satellites to PO Polyot in Omsk, which had better production capabilities.
Originally, GLONASS was designed to have an accuracy of 65 m, but in reality it had an accuracy of 20 m in the civilian signal and 10 m in the military signal. The first generation GLONASS satellites were 7.8 m tall, had a width of 7.2 m, measured across their solar panels, and a mass of 1,260 kg.
1980–1995: Achieving full orbital constellation
In the early 1980s, NPO PM received the first prototype satellites from PO Polyot for ground tests. Many of the produced parts were of low quality and NPO PM engineers had to perform substantial redesigning, leading to a delay. On 12 October 1982, three satellites, designated Kosmos-1413, Kosmos-1414, and Kosmos-1415 were launched aboard a Proton rocket. As only one GLONASS satellite was ready in time for the launch instead of the expected three, it was decided to launch it along with two mock-ups. The American media reported the event as a launch of one satellite and "two secret objects." For a long time, the Americans could not find out the nature of those "objects". The Telegraph Agency of the Soviet Union (TASS) covered the launch, describing GLONASS as a system "created to determine positioning of civil aviation aircraft, navy transport and fishing-boats of the Soviet Union".
From 1982 through April 1991, the Soviet Union successfully launched a total of 43 GLONASS-related satellites plus five test satellites. When the Soviet Union disintegrated in 1991, twelve functional GLONASS satellites in two planes were operational; enough to allow limited usage of the system (to cover the entire territory of the country, 18 satellites would have been necessary.) The Russian Federation took over control of the constellation and continued its development. In 1993, the system, now consisting of 12 satellites, was formally declared operational and in December 1995, the constellation was finally brought to its optimal status of 24 operational satellites. This brought the precision of GLONASS on-par with the American GPS system, which had achieved full operational capability two years earlier.
1996–1999: Economic crisis and fall into disrepair
Since the first generation satellites operated for 3 years each, to keep the system at full capacity, two launches per year would have been necessary to maintain the full network of 24 satellites. However, in the financially difficult period of 1989–1999, the space program's funding was cut by 80% and Russia consequently found itself unable to afford this launch rate. After the full complement was achieved in December 1995, there were no further launches until December 1999. As a result, the constellation reached its lowest point of just 6 operational satellites in 2001. As a prelude to demilitarisation, responsibility of the program was transferred from the Ministry of Defence to Russia's civilian space agency Roscosmos.
2000–2007: Renewed efforts and modernization
In the early 2000s, under Vladimir Putin's presidency, the Russian economy recovered and state finances improved considerably. Putin himself took special interest in GLONASS and the system's restoration was made one of the government's top priorities.
For this purpose, in August 2001, the Federal Targeted Program "Global Navigation System" 2002–2011 (Government Decision n.587) was launched. The program was given a budget of $420 million and aimed at restoring the full constellation by 2009. The program was divided to three phases. In the first phase, the constellation would be partially restored to 18 satellites and a new satellite type (GLONASS-M) would be introduced. In the second step (2006–2011), the system would be brought to fully operational status with 24 satellites, and another, smaller and more accurate satellite design, GLONASS-K would be introduced.
On 10 December 2003, the second generation satellite design, GLONASS-M, was launched for the first time. It had a slightly larger mass than the baseline GLONASS, standing at 1,415 kg, but it had double the original's lifetime, decreasing the required replacement rate by 50%. The new satellite also had better accuracy and ability to broadcast two extra civilian signals.
In 2006, Defence Minister Sergey Ivanov ordered one of the signals (with an accuracy of 30 m) to be made available to civilian users. Putin, however, was not satisfied with this, and demanded that the whole system should be made fully available to everyone. Consequently, on 18 May 2007, all restrictions were lifted. The accurate, formerly military-only signal with a precision of 10 m, has since then been freely available to civilian users.
During the middle of the first decade of the 2000s, the Russian economy boomed, resulting in substantial increases in the country's space budget. In 2007, the financing of the GLONASS program was increased considerably. Its budget was almost doubled: while in 2006 the GLONASS had received $181 million from the federal budget, in 2007 the amount was increased to $380 million.
In the end, 140.1 billion rubles ($4.7 billion) were spent on the program 2001–2011, making it Roscosmos' largest project and consuming a third of its 2010 budget of 84.5 billion rubles.
2008–2011: Restoring full capacity
In June 2008, the system consisted of 16 satellites, 12 of which were fully operational at the time. Roscosmos aimed at having a full constellation of 24 satellites in orbit by 2010.
Promoting commercial use
Although the GLONASS constellation is nearing global coverage, its commercialisation, especially development of the user segment, has been lacking compared to the American GPS system. For example, the first commercial Russian-made GLONASS navigation device for cars, Glospace-SGK 70, was introduced in 2007, but it was much bigger and more costly than similar GPS receivers.
A protectionistic measure for improving the GLONASS user segment was proposed by Vladimir Evtushenkov main shareholder of JFSC Sistema. In a meeting with Russian Prime Minister Vladimir Putin, Evtushenkov called for an import ban on all the GPS-capable devices unless these devices support Glonass as well. Evtushenkov claimed that Russian authorities had already started negotiations with major vendors like Nokia, Siemens and Motorola. Vladimir Putin agreed that "It is good that our partners understand our need to protect our national interests and promote our product". According to Russian experts, it was possible that mobile devices like smartphones would be effectively banned as well. Some producers claimed that if additional expenses to add GLONASS were too high, they may consider turning off satnav feature in devices for Russian market to avoid import ban.
Following a December 2006 meeting in Moscow of the GPS-GLONASS Interoperability and Compatibility Working Group (WG-1), it was announced that in the future, GLONASS satellites would transmit a CDMA in addition to the FDMA. This would make GLONASS compatible with GPS, GALILEO and Compass receivers, which also use the CDMA method. A change in the GLONASS system from its current FDMA technique to the GPS and Galileo's format would enable a simply-designed receiver to use multiple satellite systems simultaneously.
On August 11, 2010, Deputy Prime Minister Sergei Ivanov, who is in charge of GLONASS development, called for a 25% import duty on all GPS-capable devices unless they are compatible with GLONASS. The duty is proposed to be implemented from January 2011. Russian government believes this move would "stimulate international interest" in the system.
On October 27, 2010, Sergei Ivanov confirmed a plan to introduce a 25% import duty on all GPS-capable devices, including mobile phones, unless they are compatible with GLONASS. As well, the government is planning to force all car manufacturers in Russia to make cars with GLONASS starting from 2011. This will affect all car makers, including foreign brands like Ford and Toyota, which have car assembling facilities in Russia.
Current GPS and phone baseband chips from major vendors ST-Ericsson, Broadcom CSR and Qualcomm all support GLONASS in combination with GPS. Any import restriction is likely to have little change as most devices shipping worldwide will soon support GLONASS.
In 2009, the head of the Russian Federal Space Agency Anatoly Perminov announced a new GLONASS project called "ERA" (), an acronym for "Emergency Response to Accidents" (). This system will provide location services for emergency calls and is based on the European eCall standard. In 2012, interoperability tests were successfully conducted in Finland using Russian-built ERA-GLONASS terminals and eCall Public Safety Answering Call infrastructure. Test pilot zones will be launched in Russia in 2013, and by 2017 all new vehicles are required to include ERA-GLONASS equipment.
The first phase of the project will include equipping automobiles with GLONASS receivers and creation of back-end software which will provide call center operators within emergency services with geographic data. The second phase will also involve GPS/GLONASS enabled phones and smartphones.
There is also a planned project called "Social GLONASS". It will help people who require supervision, such as old people, children, and people with reduced vision.
Finishing the constellation
Russia's aim of finishing the constellation in 2010 suffered a setback when a December 2010 launch of three GLONASS-M satellites failed. The Proton-M itself performed flawlessly, but the upper stage Blok DM3 (a new version which was to make its maiden flight) was loaded with too much fuel due to a sensor failure. As a result, the upper stage and the three satellites crashed into the Pacific Ocean. Kommersant estimated the launch failure cost up to $160 million. Russian President Dmitry Medvedev ordered a full audit of the entire $2 billion program and an investigation into the failure.
Following the mishap, Roscosmos activated two reserve satellites and decided to make the first GLONASS-K satellite, to be launched in February 2011, part of the operational constellation instead of mainly for testing as was originally planned. This would bring the total number of satellites to 23, obtaining almost complete worldwide coverage. The second GLONASS-K would be ready within three to four months.
The third generation GLONASS-K satellites have an operational lifetime of 10 years, compared to the 7-year lifetime of the second generation GLONASS-M, and to the 3-year lifetime of the original GLONASS satellite. The mass of the new satellite is just 750 kg, compared to 1,450 kg of GLONASS-M. This means that two can be orbited at time on a Soyuz-2.1b rocket, or six at a time on Proton-M. In contrast, only three GLONASS-M satellites can be launched on Proton-M at a time. The new satellite design is expected to double the accuracy of the GLONASS system.
2011–2020: Transitioning to CDMA signals
On a May 28, 2014 interview, Nikolay Testoyedov — president of ISS Reshetnev — stated that production of GLONASS-M would end in 2015, with GLONASS-K being exclusively produced after that final batch. In a December 14, 2014 interview with GPS World, he stated that while the original idea was to have just two GLONASS-K1 prototypes to be followed by the GLONASS-K2 production, the international sanctions limited the supply of radiation resistant electronics. And thus, they had decided to launch an additional nine GLONASS-K1 as fleet replacement while they finished the GLONASS-K2 design. On 11 May 2015, Leonid Gusev, one of the main designers of the GLONASS system and the COSPAS-SARSAT, died at the age of 92 years.
In a May, 2015 presentation, Mr. Testoyedov expected the last GLONASS-M to fly in late 2017, with serial production of GLONASS-K1 to start flying in early 2018, just after the launch of the first GLONASS-K2 prototype. The presentation showed at least eleven additional GLONASS-K1 satellites flying until 2020. On July 30, 2015, ISS Reshtev announced that it had completed the last GLONASS-M (N° 61) spacecraft and it was putting it in storage waiting for launch, along an additional eight already built satellites.
References
GLONASS | History of GLONASS | Technology | 3,199 |
41,077,350 | https://en.wikipedia.org/wiki/OpenWorm | OpenWorm is an international open science project for the purpose of simulating the roundworm Caenorhabditis elegans at the cellular level. Although the long-term goal is to model all 959 cells of the C. elegans, the first stage is to model the worm's locomotion by simulating the 302 neurons and 95 muscle cells. This bottom up simulation is being pursued by the OpenWorm community.
As of 2014, a physics engine called Sibernetic has been built for the project and models of the neural connectome and a muscle cell have been created in NeuroML format. A 3D model of the worm anatomy can be accessed through the web via the OpenWorm browser. The OpenWorm project is also contributing to develop Geppetto, a web-based multi-algorithm, multi-scale simulation platform engineered to support the simulation of the whole organism.
Background: C. elegans
The roundworm Caenorhabditis elegans is a free-living, transparent nematode, about 1 mm in length, that lives in temperate soil environments. It is the type species of its genus.
C. elegans has one of the simplest nervous systems of any organism - its hermaphrodite type possesses only 302 neurons. Furthermore, the structural connectome of these neurons is fully mapped. There are fewer than one thousand cells in the whole body of a C. elegans worm, and because C. elegans is a model organism, each has a unique identifier and comprehensive supporting literature. Being a model organism, the genome is fully known, along with many well characterized mutants readily available, and a comprehensive literature of behavioural studies. With so few neurons and new 2-photon calcium microscopy techniques, it should soon be possible to record the complete neural activity of a living organism. The manipulation of neurons via optogenetic methods, in tandem with the foregoing technical capacities, has provided the project an unprecedented position - now able to fully characterize the neural dynamics of an entire organism.
The efforts to build an in silico model of C. elegans, although a relatively simple organism, have burgeoned the development of technologies that will make it easier to model progressively more complex organisms.
OpenWorm project
While the ultimate goal is to simulate all features of C. elegans''' behaviour, the OpenWorm community initially aimed to simulate a simple motor response: teaching the worm to crawl. To do so, the virtual worm is placed in a virtual environment. A full feedback loop is subsequently established: Environmental Stimulus > Sensory Transduction > Interneuron Firing > Motor Neuron Firing > Motor Output > Environmental Change > Sensory Transduction.
There are two main technical challenges here: modelling the neural/electrical properties of the brain as it processes the information, and modelling the mechanical properties of the body as it moves. The neural properties are being modeled by a Hodgkin-Huxley model, and the mechanical properties are being modeled by a Smoothed Particle Hydrodynamics algorithm.
The OpenWorm team built an engine called Geppetto which could integrate these algorithms and due to its modularity will be able to model other biological systems (like digestion) which the team will tackle at a later time.
The team also built an environment called NeuroConstruct which is able to output neural structures in NeuroML. Using NeuroConstruct the team reconstructed the full connectome of C. elegans.
Using NeuroML the team has also built a model of a muscle cell. Note that these models currently only model the relevant properties for the simple motor response: the neural/electrical and the mechanical properties discussed above.
The next step is to connect this muscle cell to the six neurons which synapse on it and approximate their effect.
The rough plan is to then both:
Approximate the synapses which synapse on those neurons
Repeat the process for other muscle cells
Progress
, the project is still awaiting peer review, and researchers involved in the project are reluctant to make bold claims about its current resemblance to biological behavior; project coordinator Stephen Larson estimates that they are "only 20 to 30 percent of the way towards where we need to get".
, a whole brain emulation has not yet been achieved.
Related projects
In 1998 Japanese researchers announced the Perfect C. elegans Project. A proposal was submitted, but the project appears to have been abandoned.
In 2004 a group from Hiroshima began the Virtual C. elegans Project. They released two papers which showed how their simulation would retract from virtual prodding.
In 2005 a Texas researcher described a simplified C. elegans'' simulator based on a 1-wire network incorporating a digital Parallax Basic Stamp processor, sensory inputs and motor outputs. Inputs employed 16-bit A/D converters attached to operational amplifier simulated neurons and a 1-wire temperature sensor. Motor outputs were controlled by 256-position digital potentiometers and 8-bit digital ports. Artificial muscle action was based on Nitinol actuators. It used a "sense-process-react" operating loop which recreated several instinctual behaviors.
These early attempts of simulation have been criticized for not being biologically realistic. Although we have the complete structural connectome, we do not know the synaptic weights at each of the known synapses. We do not even know whether the synapses are inhibitory or excitatory. To compensate for this the Hiroshima group used machine learning to find some weights of the synapses which would generate the desired behaviour. It is therefore no surprise that the model displayed the behaviour, and it may not represent true understanding of the system.
Open science
The OpenWorm community is committed to the ideals of open science. Generally this means that the team will try to publish in open access journals and include all data gathered (to avoid the file drawer problem). Indeed, all the biological data the team has gathered is publicly available.
By mid-2024, twenty publications made by the group are available for free on their website. All the software that OpenWorm has produced is completely free and open source.
OpenWorm is also trying a radically open model of scientific collaboration. The team consists of anyone who wishes to be a part of it. There are over one hundred "members" who are signed up for the high volume technical mailing list. Of the most active members who are named on a publication there are collaborators from Russia, Brazil, England, Scotland, Ireland and the United States.
To coordinate this international effort, the team uses "virtual lab meetings" and other online tools that are detailed in the resources section. Frontiers website, OpenWorm: an open-science approach to modeling Caenorhabditis elegans, article by Balázs Szigeti et al, dated November 3, 2014
References
External links
Homepage: OpenWorm
OpenWorm community
Milestones.
Sibernetic
Geppetto
Artificial life
Free biosimulation software
Open science
Software using the MIT license
Neuroinformatics | OpenWorm | Biology | 1,439 |
1,105,488 | https://en.wikipedia.org/wiki/Classification%20of%20Clifford%20algebras | In abstract algebra, in particular in the theory of nondegenerate quadratic forms on vector spaces, the finite-dimensional real and complex Clifford algebras for a nondegenerate quadratic form have been completely classified as rings. In each case, the Clifford algebra is algebra isomorphic to a full matrix ring over R, C, or H (the quaternions), or to a direct sum of two copies of such an algebra, though not in a canonical way. Below it is shown that distinct Clifford algebras may be algebra-isomorphic, as is the case of Cl1,1(R) and Cl2,0(R), which are both isomorphic as rings to the ring of two-by-two matrices over the real numbers.
Notation and conventions
The Clifford product is the manifest ring product for the Clifford algebra, and all algebra homomorphisms in this article are with respect to this ring product. Other products defined within Clifford algebras, such as the exterior product, and other structure, such as the distinguished subspace of generators V, are not used here. This article uses the (+) sign convention for Clifford multiplication so that
for all vectors v in the vector space of generators V, where Q is the quadratic form on the vector space V. We will denote the algebra of matrices with entries in the division algebra K by Mn(K) or End(Kn). The direct sum of two such identical algebras will be denoted by , which is isomorphic to .
Bott periodicity
Clifford algebras exhibit a 2-fold periodicity over the complex numbers and an 8-fold periodicity over the real numbers, which is related to the same periodicities for homotopy groups of the stable unitary group and stable orthogonal group, and is called Bott periodicity. The connection is explained by the geometric model of loop spaces approach to Bott periodicity: their 2-fold/8-fold periodic embeddings of the classical groups in each other (corresponding to isomorphism groups of Clifford algebras), and their successive quotients are symmetric spaces which are homotopy equivalent to the loop spaces of the unitary/orthogonal group.
Complex case
The complex case is particularly simple: every nondegenerate quadratic form on a complex vector space is equivalent to the standard diagonal form
where , so there is essentially only one Clifford algebra for each dimension. This is because the complex numbers include i by which and so positive or negative terms are equivalent. We will denote the Clifford algebra on Cn with the standard quadratic form by Cln(C).
There are two separate cases to consider, according to whether n is even or odd. When n is even, the algebra Cln(C) is central simple and so by the Artin–Wedderburn theorem is isomorphic to a matrix algebra over C.
When n is odd, the center includes not only the scalars but the pseudoscalars (degree n elements) as well. We can always find a normalized pseudoscalar ω such that . Define the operators
These two operators form a complete set of orthogonal idempotents, and since they are central they give a decomposition of Cln(C) into a direct sum of two algebras
where
The algebras Cln±(C) are just the positive and negative eigenspaces of ω and the P± are just the projection operators. Since ω is odd, these algebras are mixed by α (the linear map on V defined by ):
and therefore isomorphic (since α is an automorphism). These two isomorphic algebras are each central simple and so, again, isomorphic to a matrix algebra over C. The sizes of the matrices can be determined from the fact that the dimension of Cln(C) is 2n. What we have then is the following table:
The even subalgebra Cl(C) of Cln(C) is (non-canonically) isomorphic to Cln−1(C). When n is even, the even subalgebra can be identified with the block diagonal matrices (when partitioned into block matrices). When n is odd, the even subalgebra consists of those elements of for which the two pieces are identical. Picking either piece then gives an isomorphism with .
Complex spinors in even dimension
The classification allows Dirac spinors and Weyl spinors to be defined in even dimension.
In even dimension n, the Clifford algebra Cln(C) is isomorphic to End(CN), which has its fundamental representation on . A complex Dirac spinor is an element of Δn. The term complex signifies that it is the element of a representation space of a complex Clifford algebra, rather than that is an element of a complex vector space.
The even subalgebra Cln0(C) is isomorphic to and therefore decomposes to the direct sum of two irreducible representation spaces , each isomorphic to CN/2. A left-handed (respectively right-handed) complex Weyl spinor is an element of Δ (respectively, Δ).
Proof of the structure theorem for complex Clifford algebras
The structure theorem is simple to prove inductively. For base cases, Cl0(C) is simply , while Cl1(C) is given by the algebra by defining the only gamma matrix as .
We will also need . The Pauli matrices can be used to generate the Clifford algebra by setting , . The span of the generated algebra is End(C2).
The proof is completed by constructing an isomorphism . Let γa generate Cln(C), and generate Cl2(C). Let be the chirality element satisfying and . These can be used to construct gamma matrices for Cln+2(C) by setting for and for . These can be shown to satisfy the required Clifford algebra and by the universal property of Clifford algebras, there is an isomorphism .
Finally, in the even case this means by the induction hypothesis . The odd case follows similarly as the tensor product distributes over direct sums.
Real case
The real case is significantly more complicated, exhibiting a periodicity of 8 rather than 2, and there is a 2-parameter family of Clifford algebras.
Classification of quadratic forms
Firstly, there are non-isomorphic quadratic forms of a given degree, classified by signature.
Every nondegenerate quadratic form on a real vector space is equivalent to an isotropic quadratic form:
where is the dimension of the vector space. The pair of integers (p, q) is called the signature of the quadratic form. The real vector space with this quadratic form is often denoted Rp,q. The Clifford algebra on Rp,q is denoted Clp,q(R).
A standard orthonormal basis {ei} for Rp,q consists of mutually orthogonal vectors, p of which have norm +1 and q of which have norm −1.
Unit pseudoscalar
Given a standard basis as defined in the previous subsection, the unit pseudoscalar in Clp,q(R) is defined as
This is both a Coxeter element of sorts (product of reflections) and a longest element of a Coxeter group in the Bruhat order; this is an analogy. It corresponds to and generalizes a volume form (in the exterior algebra; for the trivial quadratic form, the unit pseudoscalar is a volume form), and lifts reflection through the origin (meaning that the image of the unit pseudoscalar is reflection through the origin, in the orthogonal group).
To compute the square , one can either reverse the order of the second group, yielding sgn(σ)e1e2⋅⋅⋅enen⋅⋅⋅e2e1, or apply a perfect shuffle, yielding sgn(σ)e1e1e2e2⋅⋅⋅enen. These both have sign , which is 4-periodic (proof), and combined with , this shows that the square of ω is given by
Note that, unlike the complex case, it is not in general possible to find a pseudoscalar that squares to +1.
Center
If n (equivalently, ) is even, the algebra Clp,q(R) is central simple and so isomorphic to a matrix algebra over R or H by the Artin–Wedderburn theorem.
If n (equivalently, ) is odd then the algebra is no longer central simple but rather has a center which includes the pseudoscalars as well as the scalars. If n is odd and (equivalently, if ) then, just as in the complex case, the algebra Clp,q(R) decomposes into a direct sum of isomorphic algebras
each of which is central simple and so isomorphic to a matrix algebra over R or H.
If n is odd and (equivalently, if ) then the center of Clp,q(R) is isomorphic to C and can be considered as a complex algebra. As a complex algebra, it is central simple and so isomorphic to a matrix algebra over C.
Classification
All told there are three properties which determine the class of the algebra Clp,q(R):
signature mod 2: n is even/odd: central simple or not
signature mod 4: : if not central simple, center is or C
signature mod 8: the Brauer class of the algebra (n even) or even subalgebra (n odd) is R or H
Each of these properties depends only on the signature modulo 8. The complete classification table is given below. The size of the matrices is determined by the requirement that Clp,q(R) have dimension 2p+q.
It may be seen that of all matrix ring types mentioned, there is only one type shared by complex and real algebras: the type M2m(C). For example, Cl2(C) and Cl3,0(R) are both determined to be M2(C). It is important to note that there is a difference in the classifying isomorphisms used. Since the Cl2(C) is algebra isomorphic via a C-linear map (which is necessarily R-linear), and Cl3,0(R) is algebra isomorphic via an R-linear map, Cl2(C) and Cl3,0(R) are R-algebra isomorphic.
A table of this classification for follows. Here runs vertically and runs horizontally (e.g. the algebra is found in row 4, column −2).
Symmetries
There is a tangled web of symmetries and relationships in the above table.
Going over 4 spots in any row yields an identical algebra.
From these Bott periodicity follows:
If the signature satisfies then
(The table is symmetric about columns with signature ..., −7, −3, 1, 5, ...)
Thus if the signature satisfies ,
See also
Dirac algebra Cl1,3(C)
Pauli algebra Cl3,0(R)
Spacetime algebra Cl1,3(R)
Clifford module
Spin representation
References
Sources
Ring theory
Clifford algebras
Mathematical classification systems | Classification of Clifford algebras | Mathematics | 2,304 |
64,219 | https://en.wikipedia.org/wiki/Bernoulli%27s%20principle | Bernoulli's principle is a key concept in fluid dynamics that relates pressure, density, speed and height. Bernoulli's principle states that an increase in the speed of a parcel of fluid occurs simultaneously with a decrease in either the pressure or the height above a datum. The principle is named after the Swiss mathematician and physicist Daniel Bernoulli, who published it in his book Hydrodynamica in 1738. Although Bernoulli deduced that pressure decreases when the flow speed increases, it was Leonhard Euler in 1752 who derived Bernoulli's equation in its usual form.
Bernoulli's principle can be derived from the principle of conservation of energy. This states that, in a steady flow, the sum of all forms of energy in a fluid is the same at all points that are free of viscous forces. This requires that the sum of kinetic energy, potential energy and internal energy remains constant. Thus an increase in the speed of the fluid—implying an increase in its kinetic energy—occurs with a simultaneous decrease in (the sum of) its potential energy (including the static pressure) and internal energy. If the fluid is flowing out of a reservoir, the sum of all forms of energy is the same because in a reservoir the energy per unit volume (the sum of pressure and gravitational potential ) is the same everywhere.
Bernoulli's principle can also be derived directly from Isaac Newton's second Law of Motion. When fluid is flowing horizontally from a region of high pressure to a region of low pressure, there is more pressure behind than in front. This gives a net force on the volume, accelerating it along the streamline.
Fluid particles are subject only to pressure and their own weight. If a fluid is flowing horizontally and along a section of a streamline, where the speed increases it can only be because the fluid on that section has moved from a region of higher pressure to a region of lower pressure; and if its speed decreases, it can only be because it has moved from a region of lower pressure to a region of higher pressure. Consequently, within a fluid flowing horizontally, the highest speed occurs where the pressure is lowest, and the lowest speed occurs where the pressure is highest.
Bernoulli's principle is only applicable for isentropic flows: when the effects of irreversible processes (like turbulence) and non-adiabatic processes (e.g. thermal radiation) are small and can be neglected. However, the principle can be applied to various types of flow within these bounds, resulting in various forms of Bernoulli's equation. The simple form of Bernoulli's equation is valid for incompressible flows (e.g. most liquid flows and gases moving at low Mach number). More advanced forms may be applied to compressible flows at higher Mach numbers.
Incompressible flow equation
In most flows of liquids, and of gases at low Mach number, the density of a fluid parcel can be considered to be constant, regardless of pressure variations in the flow. Therefore, the fluid can be considered to be incompressible, and these flows are called incompressible flows. Bernoulli performed his experiments on liquids, so his equation in its original form is valid only for incompressible flow.
A common form of Bernoulli's equation is:
where:
is the fluid flow speed at a point,
is the acceleration due to gravity,
is the elevation of the point above a reference plane, with the positive -direction pointing upward—so in the direction opposite to the gravitational acceleration,
is the static pressure at the chosen point, and
is the density of the fluid at all points in the fluid.
Bernoulli's equation and the Bernoulli constant are applicable throughout any region of flow where the energy per unit mass is uniform. Because the energy per unit mass of liquid in a well-mixed reservoir is uniform throughout, Bernoulli's equation can be used to analyze the fluid flow everywhere in that reservoir (including pipes or flow fields that the reservoir feeds) except where viscous forces dominate and erode the energy per unit mass.
The following assumptions must be met for this Bernoulli equation to apply:
the flow must be steady, that is, the flow parameters (velocity, density, etc.) at any point cannot change with time,
the flow must be incompressible—even though pressure varies, the density must remain constant along a streamline;
friction by viscous forces must be negligible.
For conservative force fields (not limited to the gravitational field), Bernoulli's equation can be generalized as:
where is the force potential at the point considered. For example, for the Earth's gravity .
By multiplying with the fluid density , equation () can be rewritten as:
or:
where
is dynamic pressure,
is the piezometric head or hydraulic head (the sum of the elevation and the pressure head) and
is the stagnation pressure (the sum of the static pressure and dynamic pressure ).
The constant in the Bernoulli equation can be normalized. A common approach is in terms of total head or energy head :
The above equations suggest there is a flow speed at which pressure is zero, and at even higher speeds the pressure is negative. Most often, gases and liquids are not capable of negative absolute pressure, or even zero pressure, so clearly Bernoulli's equation ceases to be valid before zero pressure is reached. In liquids—when the pressure becomes too low—cavitation occurs. The above equations use a linear relationship between flow speed squared and pressure. At higher flow speeds in gases, or for sound waves in liquid, the changes in mass density become significant so that the assumption of constant density is invalid.
Simplified form
In many applications of Bernoulli's equation, the change in the term is so small compared with the other terms that it can be ignored. For example, in the case of aircraft in flight, the change in height is so small the term can be omitted. This allows the above equation to be presented in the following simplified form:
where is called total pressure, and is dynamic pressure. Many authors refer to the pressure as static pressure to distinguish it from total pressure and dynamic pressure . In Aerodynamics, L.J. Clancy writes: "To distinguish it from the total and dynamic pressures, the actual pressure of the fluid, which is associated not with its motion but with its state, is often referred to as the static pressure, but where the term pressure alone is used it refers to this static pressure."
The simplified form of Bernoulli's equation can be summarized in the following memorable word equation:
Every point in a steadily flowing fluid, regardless of the fluid speed at that point, has its own unique static pressure and dynamic pressure . Their sum is defined to be the total pressure . The significance of Bernoulli's principle can now be summarized as "total pressure is constant in any region free of viscous forces". If the fluid flow is brought to rest at some point, this point is called a stagnation point, and at this point the static pressure is equal to the stagnation pressure.
If the fluid flow is irrotational, the total pressure is uniform and Bernoulli's principle can be summarized as "total pressure is constant everywhere in the fluid flow". It is reasonable to assume that irrotational flow exists in any situation where a large body of fluid is flowing past a solid body. Examples are aircraft in flight and ships moving in open bodies of water. However, Bernoulli's principle importantly does not apply in the boundary layer such as in flow through long pipes.
Unsteady potential flow
The Bernoulli equation for unsteady potential flow is used in the theory of ocean surface waves and acoustics. For an irrotational flow, the flow velocity can be described as the gradient of a velocity potential . In that case, and for a constant density , the momentum equations of the Euler equations can be integrated to:
which is a Bernoulli equation valid also for unsteady—or time dependent—flows. Here denotes the partial derivative of the velocity potential with respect to time , and is the flow speed. The function depends only on time and not on position in the fluid. As a result, the Bernoulli equation at some moment applies in the whole fluid domain. This is also true for the special case of a steady irrotational flow, in which case and are constants so equation () can be applied in every point of the fluid domain. Further can be made equal to zero by incorporating it into the velocity potential using the transformation:
resulting in:
Note that the relation of the potential to the flow velocity is unaffected by this transformation: .
The Bernoulli equation for unsteady potential flow also appears to play a central role in Luke's variational principle, a variational description of free-surface flows using the Lagrangian mechanics.
Compressible flow equation
Bernoulli developed his principle from observations on liquids, and Bernoulli's equation is valid for ideal fluids: those that are incompressible, irrotational, inviscid, and subjected to conservative forces. It is sometimes valid for the flow of gases: provided that there is no transfer of kinetic or potential energy from the gas flow to the compression or expansion of the gas. If both the gas pressure and volume change simultaneously, then work will be done on or by the gas. In this case, Bernoulli's equation—in its incompressible flow form—cannot be assumed to be valid. However, if the gas process is entirely isobaric, or isochoric, then no work is done on or by the gas (so the simple energy balance is not upset). According to the gas law, an isobaric or isochoric process is ordinarily the only way to ensure constant density in a gas. Also the gas density will be proportional to the ratio of pressure and absolute temperature; however, this ratio will vary upon compression or expansion, no matter what non-zero quantity of heat is added or removed. The only exception is if the net heat transfer is zero, as in a complete thermodynamic cycle or in an individual isentropic (frictionless adiabatic) process, and even then this reversible process must be reversed, to restore the gas to the original pressure and specific volume, and thus density. Only then is the original, unmodified Bernoulli equation applicable. In this case the equation can be used if the flow speed of the gas is sufficiently below the speed of sound, such that the variation in density of the gas (due to this effect) along each streamline can be ignored. Adiabatic flow at less than Mach 0.3 is generally considered to be slow enough.
It is possible to use the fundamental principles of physics to develop similar equations applicable to compressible fluids. There are numerous equations, each tailored for a particular application, but all are analogous to Bernoulli's equation and all rely on nothing more than the fundamental principles of physics such as Newton's laws of motion or the first law of thermodynamics.
Compressible flow in fluid dynamics
For a compressible fluid, with a barotropic equation of state, and under the action of conservative forces,
where:
is the pressure
is the density and indicates that it is a function of pressure
is the flow speed
is the potential associated with the conservative force field, often the gravitational potential
In engineering situations, elevations are generally small compared to the size of the Earth, and the time scales of fluid flow are small enough to consider the equation of state as adiabatic. In this case, the above equation for an ideal gas becomes:
where, in addition to the terms listed above:
is the ratio of the specific heats of the fluid
is the acceleration due to gravity
is the elevation of the point above a reference plane
In many applications of compressible flow, changes in elevation are negligible compared to the other terms, so the term can be omitted. A very useful form of the equation is then:
where:
is the total pressure
is the total density
Compressible flow in thermodynamics
The most general form of the equation, suitable for use in thermodynamics in case of (quasi) steady flow, is:
Here is the enthalpy per unit mass (also known as specific enthalpy), which is also often written as (not to be confused with "head" or "height").
Note that
where is the thermodynamic energy per unit mass, also known as the specific internal energy. So, for constant internal energy the equation reduces to the incompressible-flow form.
The constant on the right-hand side is often called the Bernoulli constant and denoted . For steady inviscid adiabatic flow with no additional sources or sinks of energy, is constant along any given streamline. More generally, when may vary along streamlines, it still proves a useful parameter, related to the "head" of the fluid (see below).
When the change in can be ignored, a very useful form of this equation is:
where is total enthalpy. For a calorically perfect gas such as an ideal gas, the enthalpy is directly proportional to the temperature, and this leads to the concept of the total (or stagnation) temperature.
When shock waves are present, in a reference frame in which the shock is stationary and the flow is steady, many of the parameters in the Bernoulli equation suffer abrupt changes in passing through the shock. The Bernoulli parameter remains unaffected. An exception to this rule is radiative shocks, which violate the assumptions leading to the Bernoulli equation, namely the lack of additional sinks or sources of energy.
Unsteady potential flow
For a compressible fluid, with a barotropic equation of state, the unsteady momentum conservation equation
With the irrotational assumption, namely, the flow velocity can be described as the gradient of a velocity potential . The unsteady momentum conservation equation becomes
which leads to
In this case, the above equation for isentropic flow becomes:
Derivations
Applications
In modern everyday life there are many observations that can be successfully explained by application of Bernoulli's principle, even though no real fluid is entirely inviscid, and a small viscosity often has a large effect on the flow.
Bernoulli's principle can be used to calculate the lift force on an airfoil, if the behaviour of the fluid flow in the vicinity of the foil is known. For example, if the air flowing past the top surface of an aircraft wing is moving faster than the air flowing past the bottom surface, then Bernoulli's principle implies that the pressure on the surfaces of the wing will be lower above than below. This pressure difference results in an upwards lifting force. Whenever the distribution of speed past the top and bottom surfaces of a wing is known, the lift forces can be calculated (to a good approximation) using Bernoulli's equations, which were established by Bernoulli over a century before the first man-made wings were used for the purpose of flight.
The carburetor used in many reciprocating engines contains a venturi to create a region of low pressure to draw fuel into the carburetor and mix it thoroughly with the incoming air. The low pressure in the venturi can be explained by Bernoulli's principle. In the narrow throat the air is moving at its fastest speed and therefore it is at its lowest pressure. The carburetor may or may not use the difference between the two static pressures of the Venturi effect on the air flow in order to force the fuel to flow, and for a basic carburetor uses the difference in pressure between the throat and local air pressure in the float bowl..
An injector on a steam locomotive or a static boiler.
The pitot tube and static port on an aircraft are used to determine the airspeed of the aircraft. These two devices are connected to the airspeed indicator, which determines the dynamic pressure of the airflow past the aircraft. Bernoulli's principle is used to calibrate the airspeed indicator so that it displays the indicated airspeed appropriate to the dynamic pressure.
A De Laval nozzle utilizes Bernoulli's principle to create a force by turning pressure energy generated by the combustion of propellants into velocity. This then generates thrust by way of Newton's third law of motion.
The flow speed of a fluid can be measured using a device such as a Venturi meter or an orifice plate, which can be placed into a pipeline to reduce the diameter of the flow. For a horizontal device, the continuity equation shows that for an incompressible fluid, the reduction in diameter will cause an increase in the fluid flow speed. Subsequently, Bernoulli's principle then shows that there must be a decrease in the pressure in the reduced diameter region. This phenomenon is known as the Venturi effect.
The maximum possible drain rate for a tank with a hole or tap at the base can be calculated directly from Bernoulli's equation and is found to be proportional to the square root of the height of the fluid in the tank. This is Torricelli's law, which is compatible with Bernoulli's principle. Increased viscosity lowers this drain rate; this is reflected in the discharge coefficient, which is a function of the Reynolds number and the shape of the orifice.
The Bernoulli grip relies on this principle to create a non-contact adhesive force between a surface and the gripper.
During a cricket match, bowlers continually polish one side of the ball. After some time, one side is quite rough and the other is still smooth. Hence, when the ball is bowled and passes through air, the speed on one side of the ball is faster than on the other, and this results in a pressure difference between the sides; this leads to the ball rotating ("swinging") while travelling through the air, giving advantage to the bowlers.
Misconceptions
Airfoil lift
One of the most common erroneous explanations of aerodynamic lift asserts that the air must traverse the upper and lower surfaces of a wing in the same amount of time, implying that since the upper surface presents a longer path the air must be moving over the top of the wing faster than over the bottom. Bernoulli's principle is then cited to conclude that the pressure on top of the wing must be lower than on the bottom.
Equal transit time applies to the flow around a body generating no lift, but there is no physical principle that requires equal transit time in cases of bodies generating lift. In fact, theory predicts – and experiments confirm – that the air traverses the top surface of a body experiencing lift in a shorter time than it traverses the bottom surface; the explanation based on equal transit time is false. While the equal-time explanation is false, it is not the Bernoulli principle that is false, because this principle is well established; Bernoulli's equation is used correctly in common mathematical treatments of aerodynamic lift.
Common classroom demonstrations
There are several common classroom demonstrations that are sometimes incorrectly explained using Bernoulli's principle. One involves holding a piece of paper horizontally so that it droops downward and then blowing over the top of it. As the demonstrator blows over the paper, the paper rises. It is then asserted that this is because "faster moving air has lower pressure".
One problem with this explanation can be seen by blowing along the bottom of the paper: if the deflection was caused by faster moving air, then the paper should deflect downward; but the paper deflects upward regardless of whether the faster moving air is on the top or the bottom. Another problem is that when the air leaves the demonstrator's mouth it has the same pressure as the surrounding air; the air does not have lower pressure just because it is moving; in the demonstration, the static pressure of the air leaving the demonstrator's mouth is equal to the pressure of the surrounding air. A third problem is that it is false to make a connection between the flow on the two sides of the paper using Bernoulli's equation since the air above and below are different flow fields and Bernoulli's principle only applies within a flow field.
As the wording of the principle can change its implications, stating the principle correctly is important. What Bernoulli's principle actually says is that within a flow of constant energy, when fluid flows through a region of lower pressure it speeds up and vice versa. Thus, Bernoulli's principle concerns itself with changes in speed and changes in pressure within a flow field. It cannot be used to compare different flow fields.
A correct explanation of why the paper rises would observe that the plume follows the curve of the paper and that a curved streamline will develop a pressure gradient perpendicular to the direction of flow, with the lower pressure on the inside of the curve. Bernoulli's principle predicts that the decrease in pressure is associated with an increase in speed; in other words, as the air passes over the paper, it speeds up and moves faster than it was moving when it left the demonstrator's mouth. But this is not apparent from the demonstration.
Other common classroom demonstrations, such as blowing between two suspended spheres, inflating a large bag, or suspending a ball in an airstream are sometimes explained in a similarly misleading manner by saying "faster moving air has lower pressure".
See also
Torricelli's law
Coandă effect
Euler equations – for the flow of an inviscid fluid
Hydraulics – applied fluid mechanics for liquids
Navier–Stokes equations – for the flow of a viscous fluid
Teapot effect
Terminology in fluid dynamics
Notes
References
External links
The Flow of Dry Water - The Feynman Lectures on Physics
Science 101 Q: Is It Really Caused by the Bernoulli Effect?
Bernoulli equation calculator
Millersville University – Applications of Euler's equation
NASA – Beginner's guide to aerodynamics
Misinterpretations of Bernoulli's equation – Weltner and Ingelman-Sundberg
Fluid dynamics
Eponymous laws of physics
Equations of fluid dynamics
1738 in science | Bernoulli's principle | Physics,Chemistry,Engineering | 4,616 |
13,565,582 | https://en.wikipedia.org/wiki/Phenindamine | Phenindamine (Nolahist, Thephorin) is an antihistamine and anticholinergic closely related to cyproheptadine. It was developed by Hoffman-La Roche in the late 1940s. It is used to treat symptoms of the common cold and allergies, such as sneezing, itching, rashes, and hives. Its efficacy against some symptoms of opioid withdrawal was researched in the 1950s and 1960s in a number of countries; William S. Burroughs' book Junkie mentions this technique. Like many other first-generation antihistamines, phenindamine has useful potentiating effects on many narcotic analgesics and is even more useful with those opioids which release histamine when in the body.
Nolahist was originally manufactured in the US by Carnrick Laboratories, and later by Amarin Pharmaceuticals. When that company ceased its American operations, its product line was acquired by Valeant, but they declined to resume manufacturing Nolahist. The last produced lot bore an expiration date of 10/2005, and the product is no longer available.
Phenindamine does exhibit optical isomerism as do other chemicals of its general type ranging from pethidine and alphaprodine to cyproheptadine to certain herbicides and other industrial chemicals; the. In the example at hand, the compound isophenidamine (60295-96-7 MSDS), which is inactive.
See also
Cyproheptadine
References
Abandoned drugs
H1 receptor antagonists
Muscarinic antagonists | Phenindamine | Chemistry | 327 |
230,613 | https://en.wikipedia.org/wiki/Scythe | A scythe (, rhyming with writhe) is an agricultural hand tool for mowing grass or harvesting crops. It is historically used to cut down or reap edible grains, before the process of threshing. The scythe has been largely replaced by horse-drawn and then tractor machinery, but is still used in some areas of Europe and Asia. Reapers are bladed machines that automate the cutting of the scythe, and sometimes subsequent steps in preparing the grain or the straw or hay.
The word "scythe" derives from Old English siðe. In Middle English and later, it was usually spelled sithe or sythe. However, in the 15th century some writers began to use the sc- spelling as they thought (wrongly) the word was related to the Latin scindere (meaning "to cut"). Nevertheless, the sithe spelling lingered and notably appears in Noah Webster's dictionaries.
A scythe consists of a shaft about long called a snaith, snath, snathe or sned, traditionally made of wood but now sometimes metal. Simple snaiths are straight with offset handles, others have an "S" curve or are steam bent in three dimensions to place the handles in an ergonomic configuration but close to the shaft. The snaith has either one or two short handles at right angles to it, usually one near the upper end and always another roughly in the middle. The handles are usually adjustable to suit the user. A curved, steel blade between long is mounted at the lower end at 90°, or less, to the snaith. Scythes almost always have the blade projecting from the left side of the snaith when in use, with the edge towards the mower; left-handed scythes are made but cannot be used together with right-handed scythes as the left-handed mower would be mowing in the opposite direction and could not mow in a team. Although left-handed scythes exist, their primary purpose is not to suit left-handed mowers but to mow back out from an obstruction on the left, such as when mowing back from the end of a ditch; ditch mowers may have both left and right-handed ditch scythes with them to do this.
Use
The use of a scythe was historically called mowing, now often scything to distinguish it from machine mowing. The mower holds the top handle in the left hand and the central one in the right, with the arms straight, the blade parallel and very close to the ground. The mower cuts along the mowing edge of the meadow, keeping the uncut grass to the right. The blade hooks the grass on the right and is swung to the left in a long arc ending to the left of the mower to form a windrow of cut grass on the previously mown ground. The mower takes a small step forward and repeats the motion, proceeding with a steady rhythm, stopping at frequent intervals to hone the blade. The correct technique has a slicing action on the grass, leaving a swathe of uniformly cut stubble, and forming a regular windrow on the left.
When mown in a team, the team starts at the edge of the meadow in a staggered line, then proceeds clockwise, finishing in the middle. Mowing with a scythe is a skilled task that takes time to learn fully. Long-bladed scythes, typically around (such as in the example below) and suitable for mowing grass or wheat, are harder to use at first; consequently, beginners usually start on shorter blades, generally or less. Common beginner errors include setting up the snaith with the handles in the wrong locations to suit the body, setting the blade at the wrong turn-in and turn-up angles to suit the conditions, choosing a blade that is too long for the skill level, failing to start with a sharp edge and persevering with a dull one during use, chopping or hacking at the grass, trying to cut too wide a strip of grass at once and striking the ground with the blade. Historically, beginners relied on mentors to help them set up and maintain their scythe and to teach them to mow comfortably and efficiently.
Mowing grass is easier when it is damp, and so hay-making historically began at dawn and often stopped early, the heat of the day being spent raking and carting the hay cut on previous days or peening the blades.
Scythes are designed for different tasks. A long, thin blade is most efficient for mowing grass or wheat, while a shorter, more robust scythe is more appropriate for clearing weeds, cutting reed or sedge and can be used with the blade under water for clearing ditches and waterways. Skilled mowers using long-bladed scythes honed very sharp were used to maintain short lawn grass until the invention of the lawnmower. Many cultures have used a variety of 'cradles' to catch cut different kinds of grain stems, keeping the seed heads aligned and laying them down in an orderly fashion to make them easier to sheaf and winnow.
The mowing action
Sharpening
The cutting edge of a scythe blade is maintained by occasional peening followed by frequent honing. Peening reforms the malleable edge by hammering; creating the desired edge profile, locally work-hardening the metal, and removing minor nicks and dents. For mowing fine grass, the bevel angle may be peened extremely fine, while for coarser work a larger angle is created to give a more robust edge. Peening requires some skill and is done using a peening hammer and special anvils or by using a peening jig. Historically, when mowing in teams, a peening station was set up on the edge of the field during harvest, but now more likely back in the workshop.
In the example below, a short scythe blade, being used to clear brambles, is being sharpened. Before being taken to the forest, the blade is peened in the workshop: this reforms the malleable steel to create an edge profile that can then be honed. Peening is done only occasionally; how often depends on the hardness of the steel and the nature of the work. The Austrian blade shown is being used to cut tough-stemmed brambles and it is being peened about every thirty hours of work. Nicks and cuts to the blade edge can usually be worked out of the blade by peening and a new edge profile formed for honing.
A peening jig is being used here, but blades can be free-peened using various designs of peening anvils. The peening jig shown has two interchangeable caps that set different angles: a coarse angle is set first about 3 mm back from the edge, and the fine angle is then set on the edge, leaving an edge that lends itself to being easily honed. The blade is then honed using progressively finer honing stones and then taken to the field. In the field, the blade is honed using a fine, ovoid whetstone (or rubber), fine-grained for grass, coarser for cereal crops. Honing is performed the moment the mower senses that the edge has gone off; this may be every half hour or more depending on the conditions. The laminated honing stone shown here has two grades of stone and is carried into the field soaking in a water-filled holster on the belt. A burr is set up on the outside of the blade by stroking the blade on the inside; the burr is then taken off by gently stroking it on the outside. There are many opinions, regional traditions and variations on exactly how to do this; some eastern European countries even set up the burr on the inside.
Unlike European blades, which are made from malleable steel, typical American blades are made of harder, more brittle, steel and risk cracking if peened. While the harder blade holds an edge longer and requires less frequent honing in the field, the edge can only be reshaped by grinding after heavy use or damage. This usually only needs to be done only 1–3 times a season because of the greater wear resistance of the harder steel. Some examples have a laminated construction with a hard, wear-resistant core providing the edge, and softer sides providing strength. In American blades, the edge steel is typically clad on either side with the tough iron, while some Nordic laminated blades have a layer of iron on the top only, with the edge steel comprising the bottom layer.
History
Scythes may date back as far as ; they seem to have been used since Cucuteni–Trypillia settlements, becoming widespread with agricultural developments. Initially used mostly for mowing hay, it had replaced the sickle for reaping crops by the 16th century, as the scythe was better ergonomically and consequently more efficient. In about 1800, the grain cradle was sometimes added to the standard scythe when mowing grain; the cradle was an addition of light wooden fingers above the scythe blade which kept the grain stems aligned and the heads together to make the collection and threshing easier. In the developed world, the scythe has been largely replaced by the motorised lawn mower and combine harvester. However, the scythe remained in common use for many years after the introduction of machines because a side-mounted finger-bar mowerwhether horse- or tractor-drawncould not mow in front of itself, and scythes were still needed to open up a meadow by clearing the first swathe to give the mechanical mower room to start.
The Dictionary of Greek and Roman Antiquities of Sir William Smith argues that the scythe, known in Latin as the falx foenaria as opposed to the sickle, the falx messoria, was used by the ancient Romans. According to ancient Greek mythology, Gaiathe Greek goddess and mother of the Titansgave a sickle made of the strongest metal to her youngest son Kronos, who is also the youngest of the Titans and god of the harvest, to seek vengeance against her husband Ouranos for torturing their eldest sons. The Grim Reaper is often depicted carrying or wielding a scythe. According to Jack Herer and Flesh of The Gods (Emboden, W. A. Jr., Praeger Press, New York, 1974), the ancient Scythians grew hemp and harvested it with a hand reaper that would be considered a scythe.
The Abbeydale Industrial Hamlet in Sheffield, England, is a museum of a scythe-making works that was in operation from the end of the 18th century until the 1930s. This was part of the former scythe-making district of north Derbyshire, which extended into Eckington. Other English scythe-making districts include that around Belbroughton.
The German Renaissance scythe sword, the Greek and Roman harpe and the Egyptian khopesh were scythes or sickles modified as weapons or symbols of authority. An improvised conversion of the agricultural scythe to a war scythe by re-attaching the blade parallel to the snaith, similar to a bill, has also been used throughout history as a weapon. See below for an example.
In national cultures
Although the scythe is still an indispensable tool for farmers in developing countries and in mountainous terrain, the tool has become associated with the Grim Reaper.
In Romania, for example, in the highland landscape of the Transylvanian Apuseni Mountains, scything is a very important annual activity, taking about 2–3 weeks to complete for a regular house. As scything is a tiring physical activity and is relatively difficult to learn, farmers help each other by forming teams. After each day's harvest, the farmers often celebrate by having a small feast where they dance, drink and eat, while being careful to keep in shape for the next day's hard work. In other parts of the Balkans, such as in Serbian towns, scything competitions are held where the winner takes away a small silver scythe. In small Serbian towns, scything is treasured as part of the local folklore, and the winners of friendly competitions are rewarded richly with food and drink, which they share with their competitors.
Among Basques scythe-mowing competitions are still a popular traditional sport, called segalaritza (from Spanish verb segar: to mow). Each contender competes to cut a defined section of grown grass before his rival does the same.
There is an international scything competition held at Goričko where people from Austria, Hungary, Serbia, and Romania, or as far away as Asia enter to showcase their culturally unique method of reaping crops. In 2009, a Japanese man showcased a wooden reaping tool with a metal edge, which he used to show how rice was cut. He was impressed with the speed of the local reapers, but said such a large scythe would never work in Japan.
The Norwegian municipality of Hornindal has three scythe blades in its coat-of-arms.
Their motto was They Feed and Defend (Polish: Żywią i Bronią, archaic spelling: Żywią y Bronią).
The emblem of Bnei Akiva, a Jewish religious-Zionist youth movement, contains wheat, scythe and pitchfork, representing agriculture and the combination of land labor with the Torah.
In 2012, The Wall Street Journal reported some American homeowners were eschewing motorized lawn mowers in favor of scythes, citing the lack of noise as well as the health benefits of scythe reaping as exercise.
In art
See also
Billhook, a version of the sickle used for cutting shrubs and branches
Death, a cultural personification depicted in some mythologies as wielding a scythe
Grain cradle, for aligning grain stems
Harpe, a Greek or Roman long sickle or scythe which doubled as a weapon
Kama (tool), a Japanese hand scythe used in farming, and martial arts
Khopesh, an Egyptian long sickle or scythe as a weapon
Scythe sword, scythe blade converted to use as a weapon
Sickle, the archetypal forerunner of the scythe
String trimmer, a garden tool for cutting grass and groundcover which uses a flexible monofilament line instead of a blade
War scythe, a polearm resembling a modified scythe
References
External links
Scythe Network , a site dedicated to modern usage, with links to numerous equipment suppliers in North America.
Cutting tools
Mechanical hand tools
Gardening tools
Edged and bladed weapons
Farming tools
Heraldic charges | Scythe | Physics | 3,027 |
73,792,277 | https://en.wikipedia.org/wiki/Diurnal%20mood%20variation | Diurnal mood variation or morning depression is a prominent depression symptom characterized by gradual mood improvement through the day, reaching its peak sometime after twilight. While the main form of diurnal mood variation presents itself as described, a reversed form, with a worsening of mood towards the evening, also exists. While some mood changes are generally experienced by the majority of patients diagnosed with depression, such recurrent mood instability is a consistent predictor of suicidal ideation, and may cause increased mortality. Diurnal mood variation is most strongly associated with melancholic depression, which is also referred to as endogenous or somatic depression. According to the diagnostic criteria outlined in The Diagnostic and Statistical Manual of Mental Disorders (DSM) and The International Classification of Diseases (ICD), diurnal mood variation characterized by worsening symptoms in the early morning is recognized as a hallmark symptom of melancholic features in somatic major depressive disorder.
Symptoms
Patients experiencing diurnal mood variation generally complain about the following symptoms, which gradually improve throughout the day:
feelings of sadness
irritability
trouble getting out of bed
extreme lack of energy in the morning
fatigue
psychomotor slowing
difficulty performing daily tasks, such as making the bed or dressing up
delayed cognitive function, often described as fogginess
Distinction from regular mood change
Diurnal mood variation generally does not correspond with important behavioural or environmental stimuli, unlike regular mood changes and depression in general, which can be experienced in irregular waves. According to one study, among individuals with melancholic features, mood variations tended to occur spontaneously in over half of the cases. In contrast, healthy controls predominantly attributed their mood fluctuations to their own activities or external circumstances. Patients also report a preference for performing the majority of their activities at dusk or in the evening, which is consistent with the evening chronotype. People experiencing diurnal mood variation consistently prefer later bed and wake-up times.
Pathomechanism
Although diurnal mood variation is a prevalent pattern observed in various mood disorders, there exists a gap in the literature regarding a comprehensive analysis of its underlying causes; the mechanisms underlying DMV symptoms are not well understood. Diurnal changes in activity patterns align with the characteristics of individuals with an evening chronotype, who experience their peak energy and efficiency towards the later part of the day. The body's biological clock system plays a role in regulating wake-behavior rhythms, which in turn affects a person's chronotype and influences their mood variations. Numerous studies have demonstrated that circadian rhythms have an impact on an individual's psychological well-being, including their susceptibility to psychopathological conditions. In clinical settings, individuals with a late chronotype, commonly known as evening types, have been observed to have a higher likelihood of experiencing depression. This association suggests that being an evening type may contribute to an increased risk of developing depressive symptoms.
Functional neuroimaging plays a crucial role in deepening the understanding of the neural mechanisms involved in major depressive disorder with diurnal mood variation symptoms. The circadian or clock system consists of multiple cellular clocks present in organs and tissues, and it plays a vital role in regulating brain function. Research has indicated that functional changes in the ventral and dorsal emotion neural systems are associated with diurnal mood variation symptoms. The ventral emotion neural system, which encompasses the amygdala, ventral anterior cingulate, orbitofrontal cortex, ventral striatum, and insula, is particularly involved in facilitating the experience of emotions. Previous studies have provided support for the notion that diurnal mood symptoms are linked to functional alterations in these brain regions. In one study, when compared to individuals without depression, patients diagnosed with depression exhibited decreased metabolic activity in the frontal and parietal cortex throughout the day. Interestingly, in depressed patients, improvements in mood during the evening were accompanied by increased metabolic activity in the frontal regions of the brain. These findings suggest a link between mood fluctuations and altered metabolic activity in specific brain areas in individuals with depression.
One study revealed that individuals experiencing sleep deprivation displayed a higher percentage of diurnal mood variation compared to an unaffected control group.
References
Depression (mood)
Psychiatry
Chronobiology
Mood disorders | Diurnal mood variation | Biology | 865 |
7,434,970 | https://en.wikipedia.org/wiki/Hard%20engineering | Hard engineering involves the construction of hydraulic structures to protect coasts from erosion. Such structures include seawalls, gabions, breakwaters, groynes and tetrapods.
Effects
Hard engineering can cause unintended environmental consequences, such as new erosion and altered sedimentation patterns, that are detrimental to the immediate human and natural environment or along down-coast locations and habitats.
Seawalls and bulkheads may have multiple negative effects on nearshore ecosystems due to the way they reflect wave energy instead of dissipating it. Energy from reflected waves can cause a scouring effect on substrate below the structure, resulting in loss or displacement of sediment. Over time, this effect may lead to a decrease in the size of intertidal and nearshore habitats. This effect is also known as coastal squeeze. In addition, bulkheads and seawalls offer no filtering for surface runoff, this means that anthropogenic pollutants and chemicals in armored areas may enter coastal waters relatively quickly.
Hard engineering, also called shoreline armoring, comes with other ecological effects on top of habitat loss and increased surface runoff. Structures that are built between land and sea are usually made of material not native to shoreline ecosystems. For instance, most sea walls and interlocking coastal defense structures are made of concrete, which may lend itself as habitat for invasive species rather than native ones. These structures also impede shoreline access, blocking some or all species from accessing refuge on dry land. In these armored areas, nutrient exchange between tidal and riparian ecosystems is threatened or cut off entirely. These issues arise from hard engineered sea shores, and lead many to believe that living shoreline techniques are far more beneficial ecologically and in terms of long-term erosion control.
Examples
Examples of hard engineering include:
Groynes – Low walls constructed at right angles to retain sediments that might otherwise be removed due to longshore drift. These structures absorb or reduce the energy of the waves and cause materials to be deposited on the updrift side of the groyne facing the longshore drift.
Seawalls – Seawalls are constructed to protect coastlines against wave attack by absorbing wave energy. Most seawalls are made out of concrete or stone and are built parallel to the coast. They have been constructed in thousands of locations throughout the world.
Rip-rap/rock armour – Boulders piled up against the coast that absorb the energy of the waves
Gabions – wire cages filled with rocks to absorb wave energy
References
Water and the environment | Hard engineering | Environmental_science | 508 |
60,547,623 | https://en.wikipedia.org/wiki/Tris%28trimethylsilyl%29silane | Tris(trimethylsilyl)silane is the organosilicon compound with the formula (Me3Si)3SiH (where Me = CH3). It is a colorless liquid that is classified as a hydrosilane since it contains an Si-H bond. The compound is notable as having a weak Si-H bond, with a bond dissociation energy estimated at 84 kcal/mol. For comparison, the Si-H bond in trimethylsilane is 94 kcal/mol. With such a weak bond, the compound is used as a reagent to deliver hydrogen atoms. The compound has been described as an environmentally benign analogue of tributyltin hydride.
Reactions
The compound can be prepared by protonation of tris(trimethylsilyl)silyl lithium, which is derived from tetrakis(trimethylsilyl)silane:
(Me3Si)4Si + MeLi → (Me3Si)3SiLi + Me4Si
(Me3Si)3SiLi + HCl → (Me3Si)3SiH + LiCl
Alternatively, the reaction of trimethylsilyl chloride and trichlorosilane in the presence of lithium delivers the silane directly but in modest yield:
3 Me3SiCl + HSiCl3 + 6 Li → (Me3Si)3SiH + 6 LiCl
Many coordination complexes have been prepared with (Me3Si)3Si− (hypersilyl) ligand. Chalcogenide derivatives of (Me3Si)3SiLi are also well developed:
3 Me3SiLi + E → (Me3Si)3SiELi (E = S, Se, Te)
References
Carbosilanes
Trimethylsilyl compounds | Tris(trimethylsilyl)silane | Chemistry | 375 |
1,983,847 | https://en.wikipedia.org/wiki/Institutional%20review%20board | An institutional review board (IRB), also known as an independent ethics committee (IEC), ethical review board (ERB), or research ethics board (REB), is a committee at an institution that applies research ethics by reviewing the methods proposed for research involving human subjects, to ensure that the projects are ethical. The main goal of IRB reviews is to ensure that study participants are not harmed (or that harms are minimal and outweighed by research benefits). Such boards are formally designated to approve (or reject), monitor, and review biomedical and behavioral research involving humans, and they are legally required in some countries under certain specified circumstances. Most countries use some form of IRB to safeguard ethical conduct of research so that it complies with national and international norms, regulations or codes.
The purpose of the IRB is to assure that appropriate steps are taken to protect the rights and welfare of people participating in a research study. A key goal of IRBs is to protect human subjects from physical or psychological harm, which they attempt to do by reviewing research protocols and related materials. The protocol review assesses the ethics of the research and its methods, promotes fully informed and voluntary participation by prospective subjects, and seeks to maximize the safety of subjects. They often conduct some form of risk-benefit analysis in an attempt to determine whether or not research should be conducted.
IRBs are most commonly used for studies in the fields of health and the social sciences, including anthropology, sociology, and psychology. Such studies may be clinical trials of new drugs or medical devices, studies of personal or social behavior, opinions or attitudes, or studies of how health care is delivered and might be improved. Many types of research that involves humans, such as research into which teaching methods are appropriate, unstructured research such as oral histories, journalistic research, research conducted by private individuals, and research that does not involve human subjects, are not typically required to have IRB approval.
United States mandate for IRBs
Formal review procedures for institutional human subject studies were originally developed in direct response to research abuses in the 20th century. Among the most notorious of these abuses were the experiments of Nazi physicians, which became a focus of the post-World War II Doctors' Trial, the Tuskegee Syphilis Study, a long-term project conducted between 1932 and 1972 by the U.S. Public Health Service, and numerous human radiation experiments conducted during the Cold War. Other controversial U.S. projects undertaken during this era include the Milgram obedience experiment, the Stanford prison experiment, and Project MKULTRA, a series of classified mind control studies organized by the CIA.
The result of these abuses was the National Research Act of 1974 and the development of the Belmont Report, which outlined the primary ethical principles in human subjects review; these include "respect for persons", "beneficence", and "justice". An IRB may approve only research for which the risks to subjects are balanced by potential benefits to society, and for which the selection of subjects presents a fair or just distribution of risks and benefits to eligible participants. A bona fide process for obtaining informed consent from participants is also generally needed. However, this requirement may be waived in certain circumstances – for example, when the risk of harm to participants is clearly minimal.
In the United States, IRBs are governed by Title 45 Code of Federal Regulations Part 46. These regulations define the rules and responsibilities for institutional review, which is required for all research that receives support, directly or indirectly, from the United States federal government. Specifically, research on human subjects that is conducted by any institution must be reviewed by that institution's review board if it is not an exempt type and it also involves:
is conducted by the federal government,
involves any type of federal funding (e.g., a research grant from the National Institutes of Health), or
testing an FDA-regulated product.
Additionally, the states of California and Maryland have more expansive rules for reviewing research that is conducted within those two states. Many institutions that engage in substantial amounts of research, such as research universities and research hospitals, have their board reviews all research programs, even though it is not required, as a matter of their own internal policy.
IRBs are themselves regulated by the Office for Human Research Protections (OHRP) within the Department of Health and Human Services (HHS). Additional requirements apply to IRBs that oversee clinical trials of drugs involved in new drug applications, or to studies that are supported by the United States Department of Defense. In the United States, the Food and Drug Administration (FDA) and the OHRP have empowered IRBs to approve, require modifications in planned research prior to approval, or disapprove research. IRBs are responsible for critical oversight functions for research conducted on human subjects that are "scientific", "ethical", and "regulatory". The equivalent body responsible for overseeing U.S. federally funded research using animals is the Institutional Animal Care and Use Committee (IACUC).
In addition to registering its IRB with the OHRP, an institution is also required to obtain and maintain a Federalwide Assurance or FWA, before undertaking federally funded human research. This is an agreement in which the institution commits to abiding by the regulations governing human research. A secondary supplement to the FWA is required when institutions are undertaking research supported by the U.S. Department of Defense. This DoD Addendum includes further compliance requirements for studies using military personnel, or when the human research involves populations in conflict zones, foreign prisoners, etc.
Exceptions
U.S. regulations identify several research categories that are considered exempt from IRB oversight. These categories include:
Research in conventional educational settings, such as those involving the study of instructional strategies or effectiveness of various techniques, curricula, or classroom management methods. In the case of studies involving the use of educational tests, there are specific provisions in the exemption to ensure that subjects cannot be identified or exposed to risks or liabilities.
Research involving the analysis of existing data and other materials, where the data is either already publicly available or will be analyzed such that individual subjects cannot be identified.
Studies intended to assess the performance or effectiveness of public benefit or service programs, or to evaluate food taste, quality, or consumer acceptance.
Generally, human research ethics guidelines require that decisions about exemption are made by an IRB representative, not by the investigators themselves.
Additionally, research projects conducted outside of a federal government agency or government-funded institution, such as a citizen science project conducted by a private individual or a group of private individuals, are generally not required to be approved by any institutional review board, unless the project is funded by the US federal government.
International ethics review committees
Numerous other countries have equivalent regulations or guidelines governing human subject studies and the ethics committees that oversee them. However, the organizational responsibilities and the scope of the oversight purview can differ substantially from one nation to another, especially in the domain of non-medical research. The United States Department of Health and Human Services maintains a comprehensive compilation of regulations and guidelines in other countries, as well as related standards from a number of international and regional organizations.
Naming and composition
Although "IRB" is a generic term used in the United States by the FDA and HHS, each institution that establishes such a board may use whatever name it chooses. Many simply capitalize the term "Institutional Review Board" as the proper name of their instance. Regardless of the name chosen, the IRB is subject to the US FDA's IRB regulations when studies of FDA-regulated products are reviewed and approved. At one time, such a committee was named the "Committee for the Protection of Human Subjects".
Originally, IRBs were simply committees at academic institutions and medical facilities to monitor research studies involving human participants, primarily to minimize or avoid ethical problems. Today, some of these reviews are conducted by for-profit organizations known as independent or commercial IRBs. Anyone, including private individuals, can pay a commercial IRB for review. The responsibilities of these IRBs are identical to those based at academic or medical institutions, and within the US, they are governed by the same US federal regulations.
While its composition varies, it often includes a balance of academia and non-academia members. This serves to provide a greater scope of understanding which helps ensure ethics in research. In the US, regulations set out the board's membership and composition requirements, with provisions for diversity in experience, expertise, and institutional affiliation. For example, the minimum number of members is five, at least one scientist, and at least one non-scientist. The guidance strongly suggests that the IRB contain both men and women, but there is no regulatory requirement for gender balance in the IRB's membership. The full requirements are set out in 21 CFR 56.107.
As IRBs are normally staffed with employees, who have to be paid, there are costs to operating them. In 2001, the cost of operating an IRB typically ranged from about $75,000 to $770,000 ($ to $, after accounting for inflation) per year, depending on the volume of research reviewed.
Convened and expedited reviews
Unless a research proposal is determined to be exempt (see below), the IRB undertakes its work either in a convened meeting (a "full" review) or by using an expedited review procedure. When a full review is required, a majority of the IRB members must be present at the meeting, at least one of whom has primary concern for the nonscientific aspects of the research. The research can be approved if a majority of those present are in favor.
An expedited review may be carried out if the research involves no more than minimal risk to subjects, or where minor changes are being made to previously approved research. The regulations provide a list of research categories that may be reviewed in this manner. An expedited review is carried out by the IRB chair, or by their designee(s) from the board membership. In the US, research activity cannot be disapproved by expedited review.
Pharmaceutical trials and good clinical practice
The International Conference on Harmonisation sets out guidelines for registration of pharmaceuticals in multiple countries. It defines Good Clinical Practice (GCP), which is an agreed quality standard that governments can transpose into regulations for clinical trials involving human subjects.
Here is a summary of several key regulatory guidelines for oversight of clinical trials:
Safeguard the rights, safety, and well-being of all trial subjects. Special attention should be paid to trials that may include vulnerable subjects, such as pregnant women, children, prisoners, the elderly, or persons with diminished comprehension.
Obtain trial protocol(s)/amendment(s), written Informed Consent Form(s) (ICFs) and consent form updates the investigator proposes for use in the trial, subject recruitment procedures (e.g., advertisements), written information to be provided to subjects, investigator's brochure, available safety information, information about payments and compensation available to subjects, the investigator's current curriculum vitae and/or other documentation evidencing qualifications, and any other documents the IRB may need to fulfill its responsibilities.
Review both the amount and method of payment to subjects to assure neither presents problems of coercion or undue influence on the trial subjects. Payments to a subject should be prorated and not wholly contingent on completion of the trial by the subject. Information regarding payment to subjects, including the methods, amounts, and schedule of payment to trial subjects, should be set forth in the written informed consent form and any other written information to be provided to subjects. The way payment will be prorated should be specified.
Ensure that the proposed trial is reviewed within a reasonable time and document opinions and decisions in writing, clearly identifying the trial, the documents reviewed and recorded dates for approvals, required modifications prior to approval, disapproval of a proposed trial, or termination/suspension of any prior approval. Continuing review of ongoing trials is required at intervals appropriate to the degree of risk to human subjects, but at least once per year.
The reviewers may also request that more information be given to subjects when, in their judgment, the additional information would add meaningfully to the protection of the rights, safety and/or well-being of the subjects. When a non-therapeutic trial is to be carried out with the consent of the subject's legally acceptable representative, reviewers should determine that the proposed protocol and/or other document(s) adequately address relevant ethical concerns and meets applicable regulatory requirements for such trials. Where the protocol indicates prior consent of the trial subject or the subject's legally acceptable representative is not possible, the review should determine that the proposed protocol and/or other document(s) adequately addresses relevant ethical concerns and meets applicable regulatory requirements for such trials (i.e., in emergency situations).
Adapting IRB review to social science
While the Belmont Principles and U.S. federal regulations were formulated with biomedical and social-behavioral research in mind, the enforcement of the regulations, the examples used in typical presentations regarding the history of the regulatory requirements, and the extensiveness of written guidance have been predominantly focused on biomedical research.
Numerous complaints by investigators about the fit between the federal regulations and its IRB review requirements as they relate to social science research have been received. Broad complaints range from the legitimacy of IRB review, the applicability of the concepts of risk as it pertains to social science (e.g., possibly unneeded, over-burdensome requirements), and the requirements for the documentation of participants' informed consent (i.e., consent forms). Researchers have tried to determine under what instances participants are more likely to read informed consent forms, and ways to improve their efficacy in the social sciences. IRB members have been criticized for assuming that surveys about past trauma has a re-traumatizing effect. Social scientists have criticized biomedical IRBs for failing to adequately understand their research methods (such as ethnography). For this reason, some large research institutions have set up multiple specialized IRBs, and may have one committee that exclusively oversees social science research.
In 2003, the US Office for Human Research Protections (OHRP), in conjunction with the Oral History Association and American Historical Association, issued a formal statement that taking oral histories, unstructured interviews (as if for a piece of journalism), collecting anecdotes, and similar free speech activities often do not constitute "human subject research" as defined in the regulations and were never intended to be covered by clinical research rules. In 2017, the federal government announced that effective January 2018, the regulations would no longer cover "Scholarly and journalistic activities (e.g., oral history, journalism, biography, literary criticism, legal research, and historical scholarship), including the collection and use of information that focus directly on the specific individuals about whom the information is collected."
Other US federal agencies supporting social science have attempted to provide guidance in this area, especially the National Science Foundation. In general, the NSF guidelines assure IRBs that the regulations have some flexibility and rely on the common sense of the IRB to focus on limiting harm, maximizing informed consent, and limiting bureaucratic limitations of valid research.
Adapting IRB review to big data research
Aspects of big data research pose formidable challenges for research ethics and thus show potential for wider applicability of formal review processes. One theme is data breaches, but another with high difficulty is potentially dangerous predictive analytics with unintended consequences, via false-positives or new ways to invade privacy. A 2016 article on the hope to expand ethics reviews of such research included an example of a data breach in which a big data researcher leaked 70,000 OkCupid profiles with usernames and sexual orientation data. It also gave an example of potential privacy invasion and government repression in which machine learning was used to build automated gaydar, labeling strangers as "probably gay" based on their facial photographs. Analogies with phrenology and Nazis identifying people as "probably part-Jewish" based on facial features have been made to show what can go wrong with research whose authors may have failed to adequately think through the risks of harm. Such challenges broach familiar themes, such as mistaken identity, pre-crime, and persecution, in new applications.
Relationship with citizen science
Generally speaking, citizen science, whether conducted by a single private individual or a group of individuals, is not required to follow the IRB process. This is true even if some of the individuals involved are professional researchers or are also employed at institutions that normally review all research conducted by the institution.
However, many academic journals require proof of IRB approval for all human-subject research, even when it is not legally required, which means that citizen scientists may be unable to publish scientific papers describing their findings. Citizen scientists who expect to need IRB approval for publication or to comply with the terms of a research grant can pay a commercial IRB company. In the US, a standard initial review often costs a few thousand dollars; a review to determine that the project is less expensive.
The IRB-based approach to ethics assumes that human-subject research is conducted by an institution employing researchers, and that the institution and researchers have far more power and knowledge than the participants. The researchers and the participants are seen as distinct groups, and the concern is to prevent the researchers from exploiting the participants as a means to an end. This leads to IRBs issuing requirements such as having researchers explain the research project and obtain informed consent. However, this model does not always fit citizen science projects, especially when the participants are themselves the experts and researchers. In such cases, a requirement to explain the project means participants would absurdly be informing themselves of their own plans. In a citizen science project, the boundaries between the researcher and the participant are blurred. Similarly, many institutionally-driven research programs are limiting or prohibiting the return of results to individuals, especially for genetic or medical studies, for fear that some participants could be harmed if they misunderstand the results. In this restrictive model, the participant never finds out their test results, or they can only find out their test results if the researchers carefully explain the results to them. But in a citizen science project, learning the results is a highly desired reason for participating, and, since the researchers are themselves participants, it would be impossible to prevent them from obtaining the results.
Criticism
Conflicts of interest
While the IRB approval and oversight process is designed to protect the rights and welfare of the research subjects, it has been the subject of criticism, by bioethicists and others, for conflicts of interest resulting in lax oversight. In 2005, the for-profit Western Institutional Review Board claimed to conduct the majority of reviews for new drug submissions to the FDA. In a 2006 study of 575 IRB members at university medical centers, over one-third reported industry financial ties, and over one-third admitted they "rarely or never" disclosed conflicts of interest to other board members.
In 2009 the US Government Accountability Office (GAO) set up a series of undercover tests to determine whether the IRB system was vulnerable to unethical manipulation. In one test, a fake product "Adhesiabloc" was submitted to a number of IRBs for approval for human tests. The product, company, and CVs of the supposed researchers were all fictitious and documents were forged by the GAO. The product was deliberately formulated to match some "significant risk" criteria of the FDA and was described by GAO as a "gel that would be poured into a patient's stomach after surgery to collect the bits and pieces left over from an operation." Despite this, one IRB approved the device for human testing. Other IRBs to whom the device was submitted rejected the application, one of them saying it was "the riskiest thing I've ever seen on this board". However, none of the IRBs approached detected that the company and product were fake. The GAO also set up a fake IRB and obtained requests for approval from companies. They succeeded in getting assurance approval from the HHS for their fake IRB. At the time, the US HHS has only three staff to deal with 300 IRB registrations and 300 assurance applications per month. HHS stated that it would not be worthwhile to carry out additional evaluation even if they had the staff to do it.
See also
Clinical trial
Data monitoring committee
Declaration of Helsinki
Ethical problems using children in clinical trials
Ethics committee (European Union)
Ethics & Human Research (journal), formerly IRB: Ethics & Human Research , published by The Hastings Center
Informed consent
Inside the Ethics Committee
National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research
Office for Human Research Protections
Unethical human experimentation in the United States
References
Further reading
Enfield, K. B. & Truwit, J. D. (2008). The Purpose, Composition, and Function of an Institutional Review Board: Balancing Priorities. Respiratory Care, 53, 1330–1336.
Fairchild, A. L. & Bayer, R. (1999). Uses and Abuses of Tuskegee. American Association for the Advancement of Science, 284, 919–921.
Perrault, E. K. & Nazione, S. A. (2016). "Informed Consent—Uninformed Participants: Shortcomings of Online Social Science Consent Forms and Recommendations for Improvement". Journal of Empirical Research on Human Research Ethics. 11(3), 274–280. .
Pope, T. M. (2009). Multi-Institutional Healthcare Ethics Committees: The Procedurally Fair Internal Dispute Resolution Mechanism, 31 Campbell Law Review 257–331.
External links
Human Research Report—a monthly newsletter for IRBs
Office for Human Research Protections (OHRP) at HHS
Ethics & Human Research – a peer-reviewed journal of The Hastings Center
Ethics for Sale: For-profit ethical review, coming to a clinical trial near you, Carl Elliott and Trudo Lemmens, Slate, December 13, 2005
Design of experiments
Human subject research
Clinical research ethics
Medical ethics
Nursing ethics
Drug safety
Social research
Ethics organizations
Ethics and statistics
Professional ethics
Regulatory compliance | Institutional review board | Chemistry,Technology | 4,510 |
21,547,318 | https://en.wikipedia.org/wiki/List%20of%20LED%20failure%20modes | The most common way for LEDs (and diode lasers) to fail is the gradual lowering of light output and loss of efficiency. Sudden failures, however rare, can occur as well. Early red LEDs were notable for their short lifetime.
Packaging-related
Epoxy degradation: Some materials of the plastic package tend to yellow when subjected to heat, causing partial absorption (and therefore loss of efficiency) of the affected wavelengths.
Thermal stress: Sudden failures are most often caused by thermal stresses. When the epoxy resin package reaches its glass transition temperature, it starts rapidly expanding, causing mechanical stresses on the semiconductor and the bonded contact, weakening it or even tearing it off. Conversely, very low temperatures can cause cracking of the packaging.
Differentiated phosphor degeneration: The different phosphors used in white LEDs tend to degrade with heat and age, but at different rates causing changes in the produced light color, for example, purple and pink LEDs often use an organic phosphor formulation which may degrade after just a few hours of operation causing a major shift in output color.
Semiconductor and metal related
Nucleation and growth of dislocations: This is a known mechanism for degradation of the active region, where the radiative recombination occurs. It requires a presence of an existing defect in the crystal and is accelerated by heat, high current density, and emitted light. Gallium arsenide and aluminium gallium arsenide are more susceptible to this mechanism than gallium arsenide phosphide and indium phosphide. Due to different properties of the active regions, gallium nitride and indium gallium nitride are virtually insensitive to this kind of defect.
Electromigration: This is caused by high current density and can move atoms out of the active regions, leading to emergence of dislocations and point defects, acting as nonradiative recombination centers and producing heat instead of light.
Ionizing radiation: It can lead to the creation of defects, which leads to issues with radiation hardening of circuits containing LEDs (e.g., in optoisolators)
Metal diffusion: Caused by high electrical currents or voltages at elevated temperatures, metal diffusion can move metal atoms from the electrodes into the active region. Some materials, notably indium tin oxide and silver, are subject to electromigration which causes leakage current and non-radiative recombination along the chip edges. In some cases, especially with GaN/InGaN diodes, a barrier metal layer is used to hinder the electromigration effects.
Short circuits: Mechanical stresses, high currents, and a corrosive environment can lead to formation of whiskers, causing short circuits.
Stress-related
Thermal runaway: Non-homogeneities in the substrate, causing localized loss of thermal conductivity, can cause thermal runaway where heat causes damage which causes more heat etc. Most common ones are voids caused by incomplete soldering, or by electromigration effects and Kirkendall voiding.
Current crowding: A non-homogeneous distribution of the current density over the junction can lead to the formation of current filaments. This may lead to creation of localized hot spots, which poses risk of thermal runaway.
Electrostatic discharge: An ESD may cause immediate failure of the semiconductor junction, a permanent shift of its parameters, or latent damage causing increased rate of degradation. LEDs and lasers grown on sapphire substrate (see silicon on sapphire) are more susceptible to ESD damage.
Reverse bias: Although the LED is based on a diode junction and is nominally a rectifier, the reverse-breakdown mode for some types can occur at very low voltages and essentially any excess reverse bias can cause immediate degradation, and may lead to vastly accelerated failure. 5 V is a typical maximum reverse bias voltage specification for ordinary LEDs; some special types may have lower limits.
Catastrophic optical damage: Can occur in high power semiconductor lasers.
References
Light-emitting diodes
Semiconductor device defects | List of LED failure modes | Technology | 834 |
3,746,579 | https://en.wikipedia.org/wiki/New%20methylene%20blue | is an organic compound of the thiazine class of heterocycles. It is used as a stain and as an antimicrobial agent. It is classified as an azine dye, and the chromophore is a cation, the anion is often unspecified.
Applications
NMB is a staining agent used in diagnostic cytopathology and histopathology, typically for staining immature red blood cells. It is a supravital stain. It is closely related to methylene blue, an older stain in wide use.
Safety
New methylene blue is toxic. Skin contact or inhalation should be avoided.
See also
Methylene blue
References
Biochemistry detection methods
Thiazine dyes
Vital stains
Histology | New methylene blue | Chemistry,Biology | 151 |
5,593,281 | https://en.wikipedia.org/wiki/Wisconsin%20Integrally%20Synchronized%20Computer | The Wisconsin Integrally Synchronized Computer (WISC) was an early digital computer designed and built at the University of Wisconsin–Madison. Operational in 1954, it was the first digital computer in the state.
Pioneering computer designer Gene Amdahl drafted the WISC's design as his PhD thesis. The computer was built over the period 1951-1954. It had 1,024 50-bit words (equivalent to about 6 KB) of drum memory, with an operation time of 1/15 second and throughput of 60 operations per second, which was achieved by an early form of instruction pipeline. It was capable of both fixed and floating point operation.
It weighed about .
The WISC is part of the permanent collection of the Computer History Museum.
References
External links
Oral history interview with Gene M. Amdahl. Charles Babbage Institute, University of Minnesota, Minneapolis. Amdahl starts by describing his early life and education, recalling his experiences teaching in the Advanced Specialized Training Program during and after World War II. Amdahl discusses his graduate work at the University of Wisconsin and his direction of the design and construction of the Wisconsin Integrally Synchronized Computer. Describes his role in the design of several computers for IBM including the STRETCH, IBM 701, 701A, and IBM 704. He discusses his work with Nathaniel Rochester and IBM's management of the design process for computers. He also mentions his work with Ramo-Wooldridge, Aeronutronic, and Computer Sciences Corporation.
Contains Gene Amdahl's PhD thesis and WISC User's Manual
Photos:
Early computers
One-of-a-kind computers | Wisconsin Integrally Synchronized Computer | Technology | 332 |
78,262,034 | https://en.wikipedia.org/wiki/NGC%203833 | NGC 3833 is a barred spiral galaxy located in the constellation Virgo, about 280 million light-years from Earth. Discovered by astronomer William Herschel on April 15, 1784, NGC 3833 has a Hubble classification of "Sc," indicating loosely wound spiral arms and a relatively small central bulge. The galaxy spans roughly 1.4 by 0.7 arcminutes in the night sky and shines with an apparent magnitude of around 13.5, making it a faint object suitable for observation with larger telescopes.
Due to its distance and redshift (z ≈ 0.020214), NGC 3833 is part of the large Virgo Cluster of galaxies, a group containing thousands of galaxies. In various catalogs, it is also known as PGC 36441 and UGC 6692.
Characteristics
NGC 3833 is classified as a barred spiral galaxy (type Sc) within the constellation Virgo. It exhibits a loosely wound structure with a small central bulge, characteristic of its classification. The galaxy spans approximately 1.4 arcminutes in length and 0.7 arcminutes in width, making it relatively small in apparent size compared to other galaxies.
With an apparent magnitude of around 13.5, NGC 3833 is a faint object that requires moderate to large telescopes for observation. It has a surface brightness of 13.3 magnitudes per square arcminute, indicating how dim it appears against the background of the night sky. The galaxy's redshift value of 0.020214 translates to a recessional velocity of approximately 6,060 km/s, placing it roughly 280 million light-years away from Earth.
References
Barred spiral galaxies
3833
Virgo (constellation)
Discoveries by William Herschel
Galaxies discovered in 1784 | NGC 3833 | Astronomy | 362 |
50,768,319 | https://en.wikipedia.org/wiki/Multiple%20scattering%20theory | Multiple scattering theory (MST) is the mathematical formalism that is used to describe the propagation of a wave through a collection of scatterers. Examples are acoustical waves traveling through porous media, light scattering from water droplets in a cloud, or x-rays scattering from a crystal. A more recent application is to the propagation of quantum matter waves like electrons or neutrons through a solid.
As pointed out by Jan Korringa, the origin of this theory can be traced back to an 1892 paper by Lord Rayleigh. An important mathematical formulation of the theory was made by Paul Peter Ewald. Korringa and Ewald acknowledged the influence on their work of the 1903 doctoral dissertation of Nikolai Kasterin, portions of which were published in German in the Proceedings of the Royal Academy of Sciences in Amsterdam under the sponsorship of Heike Kamerlingh Onnes. The MST formalism is widely used for electronic structure calculations as well as diffraction theory, and is the subject of many books.
The multiple-scattering approach is the best way to derive one-electron Green's functions. These functions differ from the Green's functions used to treat the many-body problem, but they are the best starting point for calculations of the electronic structure of condensed matter systems that cannot be treated with band theory.
The terms "multiple scattering" and "multiple scattering theory" are often used in other contexts. For examples, Molière's theory of the scattering of fast charged particles in matter, or Glauber multiple scattering theory for high-energy particle multiple-scattering off nucleons in a nucleus are also denominated that way.
Mathematical formulation
The MST equations can be derived with different wave equations, but one of the simplest and most useful ones is the Schrödinger equation for an electron moving in a solid. With the help of density functional theory, this problem can be reduced to the solution of a one-electron equation
where the effective one-electron potential, , is a functional of the density of the electrons in the system.
In the Dirac notation, the wave equation can be written as an inhomogeneous equation, , where is the kinetic energy operator. The solution of the homogeneous equation is , where . A formal solution of the inhomogeneous equation is the sum of the solution of the homogeneous equation with a particular solution of the inhomogeneous equation , where .
This is the Lippmann–Schwinger equation, which can also be written . The t-matrix is defined by .
Suppose that the potential is the sum of non-overlapping potentials, . The physical meaning of this is that it describes the interaction of the electron with a cluster of atoms having nuclei located at positions . Define an operator so that can be written as a sum . Inserting the expressions for and into the definition of leads to
,
so , where is the scattering matrix for one atom. Iterating this equation leads to
.
The solution of the Lippmann-Schwinger equation can thus be written as the sum of an incoming wave on any site and the outgoing wave from that site
.
The site that we have chosen to focus on can be any of the sites in the cluster. The incoming wave on this site is the incoming wave on the cluster and the outgoing waves from all the other sites
.
The outgoing wave from the site is defined as
.
These last two equations are the fundamental equations of multiple scattering.
To apply this theory to x-ray or neutron diffraction we go back to the Lippmann–Schwinger equation, . The scattering from a site is assumed to be very small, so or . The Born approximation is used to calculate the t-matrix, which simply means that is replaced with . A plane wave impinges on a site, and a spherical wave exits it. The outgoing wave from the crystal is determined by the constructive interference of the waves from the sites. Advances to this theory involve the inclusion of higher-order terms in the total scattering matrix , such as. These terms are particularly important in the scattering of charged particles treated by Molière.
Multiple scattering theory of electronic states in solids
In 1947, Korringa pointed out that the multiple scattering equations can be used to calculate stationary states in a crystal for which the number of scatterers goes to infinity. Setting the incoming wave on the cluster and the outgoing wave from the cluster to zero, he wrote the first multiple scattering as
.
A simple description of this process is that the electrons scatter from one atom to the other ad infinitum.
Since the are bounded in space and do not overlap, there is an interstitial region between them within which the potential is a constant, usually taken to be zero. In this region, the Schrödinger equation becomes , where . The incoming wave on site can thus be written in the position representation
,
where the are undetermined coefficients and . The Green's function may be expanded in the interstitial region
,
and the outgoing Hankel function can be written
.
This leads to a set of homogeneous simultaneous equations that determines the unknown coefficients
,
which is a solution in principle of the multiple scattering equations for stationary states. This theory is very important for studies in condensed matter physics.
Periodic solids, one atom per unit cell
The calculation of stationary states is simplified considerably for periodic solids in which all of the potentials are the same, and the nuclear positions form a periodic array. Bloch's theorem holds for such a system, which means that the solutions of the Schrödinger equation may be written as a Bloch wave .
It is more convenient to deal with a symmetric matrix for the coefficients, and this can be done by defining
.
These coefficients satisfy the set of linear equations , with the elements of the matrix being
,
and the are the elements of the inverse of the t-matrix.
For a Bloch wave the coefficients depend on the site only through a phase factor, , and the satisfy the homogeneous equations
,
where and .
Walter Kohn and Norman Rostoker derived this same theory using the Kohn variational method. It is called the Korringa–Kohn–Rostoker method (KKR method) for band theory calculations. Ewald derived a mathematically sophisticated summation process that makes it possible to calculate the structure constants, . The energy eigenvalues of the periodic solid for a particular , , are the roots of the equation . The eigenfunctions are found by solving for the with . The dimension of these matrix equations is technically infinite, but by ignoring all contributions that correspond to an angular momentum quantum number greater than , they have dimension . The justification for this approximation is that the matrix elements of the t-matrix are very small when and are greater than , and the elements of the inverse matrix are very large.
In the original derivations of the KKR method, spherically symmetric muffin-tin potentials were used. Such potentials have the advantage that the inverse of the scattering matrix is diagonal in
,
where is the scattering phase shift that appears in the partial wave analysis in scattering theory. It is also easier to visualize the waves scattering from one atom to another, and can be used in many applications. The muffin-tin approximation is adequate for most metals in a close-packed arrangement. It cannot be used for calculating forces between atoms, or for important systems like semiconductors.
Extensions of the theory
It is now known that the KKR method can be used with space-filling non-spherical potentials. It can be extended to treat crystals with any number of atoms in a unit cell. There are versions of the theory that can be used to calculate surface states.
The arguments that lead to a multiple scattering solution for the single-particle orbital can also be used to formulate a multiple scattering version of the single-particle Green's function which is a solution of the equation
.
The potential is the same one from density functional theory that was used in the preceding discussion. With this Green's function and the Korringa–Kohn–Rostoker method, the Korringa–Kohn–Rostoker coherent potential approximation (KKR-CPA) is obtained. The KKR-CPA is used to calculate the electronic states for substitutional solid-solution alloys, for which Bloch's theorem does not hold. The electronic states for an even wider range of condensed matter structures can be found using the locally self-consistent multiple scattering (LSMS) method, which is also based on the single-particle Green's function.
References
Scattering theory
Quantum mechanics | Multiple scattering theory | Physics,Chemistry | 1,748 |
45,275,735 | https://en.wikipedia.org/wiki/Heinz%20Werner%27s%20orthogenetic%20principle | Heinz Werner's orthogenetic principle is a foundation for current theories of developmental psychology and developmental psychopathology. Initially proposed in 1940, it was formulated in 1957 and states that "wherever development occurs it proceeds from a state of relative globality and lack of differentiation to a state of increasing differentiation, articulation, and hierarchic integration." It is an example of an organismic theory based on the intrinsic activity of living systems and is parallel to Piaget's genetic epistemology both emphasizing a holistic view of development.
In contrast to stage theories of development such as Sigmund Freud's description of psychosexual development that posited a particular sequence of behavior, Werner's principle provides a direction for development that can be applied to any behavioral domain. He asserted that the principle provided a single framework for understanding change in child psychology, psychopathology, ethnopsychology, and individual differences. He believed that although the content of these areas may be different, there was a formal similarity of the sequences within each domain moving from the global to the hierarchically integrated.
References
Developmental psychology | Heinz Werner's orthogenetic principle | Biology | 230 |
6,101,309 | https://en.wikipedia.org/wiki/Quantities%20of%20information | The mathematical theory of information is based on probability theory and statistics, and measures information with several quantities of information. The choice of logarithmic base in the following formulae determines the unit of information entropy that is used. The most common unit of information is the bit, or more correctly the shannon, based on the binary logarithm. Although bit is more frequently used in place of shannon, its name is not distinguished from the bit as used in data processing to refer to a binary value or stream regardless of its entropy (information content). Other units include the nat, based on the natural logarithm, and the hartley, based on the base 10 or common logarithm.
In what follows, an expression of the form is considered by convention to be equal to zero whenever is zero. This is justified because for any logarithmic base.
Self-information
Shannon derived a measure of information content called the self-information or "surprisal" of a message :
where is the probability that message is chosen from all possible choices in the message space . The base of the logarithm only affects a scaling factor and, consequently, the units in which the measured information content is expressed. If the logarithm is base 2, the measure of information is expressed in units of shannons or more often simply "bits" (a bit in other contexts is rather defined as a "binary digit", whose average information content is at most 1 shannon).
Information from a source is gained by a recipient only if the recipient did not already have that information to begin with. Messages that convey information over a certain (P=1) event (or one which is known with certainty, for instance, through a back-channel) provide no information, as the above equation indicates. Infrequently occurring messages contain more information than more frequently occurring messages.
It can also be shown that a compound message of two (or more) unrelated messages would have a quantity of information that is the sum of the measures of information of each message individually. That can be derived using this definition by considering a compound message providing information regarding the values of two random variables M and N using a message which is the concatenation of the elementary messages m and n, each of whose information content are given by and respectively. If the messages m and n each depend only on M and N, and the processes M and N are independent, then since (the definition of statistical independence) it is clear from the above definition that .
An example: The weather forecast broadcast is: "Tonight's forecast: Dark. Continued darkness until widely scattered light in the morning." This message contains almost no information. However, a forecast of a snowstorm would certainly contain information since such does not happen every evening. There would be an even greater amount of information in an accurate forecast of snow for a warm location, such as Miami. The amount of information in a forecast of snow for a location where it never snows (impossible event) is the highest (infinity).
Entropy
The entropy of a discrete message space is a measure of the amount of uncertainty one has about which message will be chosen. It is defined as the average self-information of a message from that message space:
where
denotes the expected value operation.
An important property of entropy is that it is maximized when all the messages in the message space are equiprobable (e.g. ). In this case .
Sometimes the function is expressed in terms of the probabilities of the distribution:
where each and
An important special case of this is the binary entropy function:
Joint entropy
The joint entropy of two discrete random variables and is defined as the entropy of the joint distribution of and :
If and are independent, then the joint entropy is simply the sum of their individual entropies.
(Note: The joint entropy should not be confused with the cross entropy, despite similar notations.)
Conditional entropy (equivocation)
Given a particular value of a random variable , the conditional entropy of given is defined as:
where is the conditional probability of given .
The conditional entropy of given , also called the equivocation of about is then given by:
This uses the conditional expectation from probability theory.
A basic property of the conditional entropy is that:
Kullback–Leibler divergence (information gain)
The Kullback–Leibler divergence (or information divergence, information gain, or relative entropy) is a way of comparing two distributions, a "true" probability distribution , and an arbitrary probability distribution . If we compress data in a manner that assumes is the distribution underlying some data, when, in reality, is the correct distribution, Kullback–Leibler divergence is the number of average additional bits per datum necessary for compression, or, mathematically,
It is in some sense the "distance" from to , although it is not a true metric due to its not being symmetric.
Mutual information (transinformation)
It turns out that one of the most useful and important measures of information is the mutual information, or transinformation. This is a measure of how much information can be obtained about one random variable by observing another. The mutual information of relative to (which represents conceptually the average amount of information about that can be gained by observing ) is given by:
A basic property of the mutual information is that:
That is, knowing , we can save an average of bits in encoding compared to not knowing . Mutual information is symmetric:
Mutual information can be expressed as the average Kullback–Leibler divergence (information gain) of the posterior probability distribution of given the value of to the prior distribution on :
In other words, this is a measure of how much, on the average, the probability distribution on will change if we are given the value of . This is often recalculated as the divergence from the product of the marginal distributions to the actual joint distribution:
Mutual information is closely related to the log-likelihood ratio test in the context of contingency tables and the multinomial distribution and to Pearson's χ2 test: mutual information can be considered a statistic for assessing independence between a pair of variables, and has a well-specified asymptotic distribution.
Differential entropy
The basic measures of discrete entropy have been extended by analogy to continuous spaces by replacing sums with integrals and probability mass functions with probability density functions. Although, in both cases, mutual information expresses the number of bits of information common to the two sources in question, the analogy does not imply identical properties; for example, differential entropy may be negative.
The differential analogies of entropy, joint entropy, conditional entropy, and mutual information are defined as follows:
where is the joint density function, and are the marginal distributions, and is the conditional distribution.
See also
Information theory
References
Information theory | Quantities of information | Mathematics,Technology,Engineering | 1,394 |
4,157,154 | https://en.wikipedia.org/wiki/Small%20dodecicosahedron | In geometry, the small dodecicosahedron (or small dodekicosahedron) is a nonconvex uniform polyhedron, indexed as U50. It has 32 faces (20 hexagons and 12 decagons), 120 edges, and 60 vertices. Its vertex figure is a crossed quadrilateral.
Related polyhedra
It shares its vertex arrangement with the great stellated truncated dodecahedron. It additionally shares its edges with the small icosicosidodecahedron (having the hexagonal faces in common) and the small ditrigonal dodecicosidodecahedron (having the decagonal faces in common).
References
External links
Uniform polyhedra | Small dodecicosahedron | Physics | 148 |
38,140 | https://en.wikipedia.org/wiki/Wide%20area%20network | A wide area network (WAN) is a telecommunications network that extends over a large geographic area. Wide area networks are often established with leased telecommunication circuits.
Businesses, as well as schools and government entities, use wide area networks to relay data to staff, students, clients, buyers and suppliers from various locations around the world. In essence, this mode of telecommunication allows a business to effectively carry out its daily function regardless of location. The Internet may be considered a WAN. Many WANs are, however, built for one particular organization and are private. WANs can be separated from local area networks (LANs) in that the latter refers to physically proximal networks.
Design options
The textbook definition of a WAN is a computer network spanning regions, countries, or even the world. However, in terms of the application of communication protocols and concepts, it may be best to view WANs as computer networking technologies used to transmit data over long distances, and between different networks. This distinction stems from the fact that common local area network (LAN) technologies operating at lower layers of the OSI model (such as the forms of Ethernet or Wi-Fi) are often designed for physically proximal networks, and thus cannot transmit data over tens, hundreds, or even thousands of miles or kilometres.
WANs are used to connect LANs and other types of networks together so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization's LAN to the Internet.
WANs are often built using leased lines. At each end of the leased line, a router connects the LAN on one side with a second router within the LAN on the other. Because leased lines can be very expensive, instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions. Protocols including Packet over SONET/SDH, Multiprotocol Label Switching (MPLS), Asynchronous Transfer Mode (ATM) and Frame Relay are often used by service providers to deliver the links that are used in WANs. It is also possible to build a WAN with Ethernet.
Academic research into wide area networks can be broken down into three areas: mathematical models, network emulation, and network simulation.
Performance improvements are sometimes delivered via wide area file services or WAN optimization.
Private networks
Of the approximately four billion addresses defined in IPv4, about 18 million addresses in three ranges are reserved for use in private networks. Packets addressed in these ranges are not routable on the public Internet; they are ignored by all public routers. Therefore, private hosts cannot directly communicate with public networks, but require network address translation at a routing gateway for this purpose.
{| class="wikitable"
|+ Reserved private IPv4 network ranges
|-
!Name!!CIDR block!!Address range!!Number of addresses!!Obsolete classful description
|-
|24-bit block||10.0.0.0/8||10.0.0.0 – 10.255.255.255||align="right"|||Single Class A.
|-
|20-bit block|||172.16.0.0/12||172.16.0.0 – 172.31.255.255||align="right"|||Contiguous range of 16 Class B blocks.
|-
|16-bit block||192.168.0.0/16||192.168.0.0 – 192.168.255.255||align="right"|||Contiguous range of 256 Class C blocks.
|}
Since two private networks, e.g., two branch offices, cannot directly communicate via the public Internet, the two networks must be bridged across the Internet via a virtual private network (VPN) or other form of IP tunnel that encapsulates packets, including their headers containing the private addresses, for transmission across the public network. Additionally, encapsulated packets may be encrypted to secure their data.
Connection technology
Many technologies are available for wide area network links. Examples include circuit-switched telephone lines, radio wave transmission, and optical fiber. New developments have successively increased transmission rates. In , a line was normal on the edge of the WAN, while core links of 56 or 64 kbit/s were considered fast. Today, households are connected to the Internet with dial-up, asymmetric digital subscriber line (ADSL), cable, WiMAX, cellular network or fiber. The speeds that people can currently use range from 28.8 kbit/s through a 28K modem over a telephone connection to speeds as high as 100 Gbit/s using 100 Gigabit Ethernet.
The following communication and networking technologies have been used to implement WANs.
Asynchronous Transfer Mode
Cable modem
Cellular networks
Dial-up internet
Digital subscriber line
Fiber-optic communication
Frame Relay
ISDN
Leased line
SD-WAN
Synchronous optical networking
Very small aperture terminal (VSAT)
Wi-Fi
WiMAX
X.25
AT&T conducted trials in 2017 for business use of 400-gigabit Ethernet. Researchers Robert Maher, Alex Alvarado, Domaniç Lavery, and Polina Bayvel of University College London were able to increase networking speeds to 1.125 terabits per second. Christos Santis, graduate student Scott Steger, Amnon Yariv, Martin and Eileen Summerfield developed a new laser that potentially quadruples transfer speeds with fiber optics.
See also
Cell relay
Internet area network (IAN)
Label switching
Low-power wide-area network (LPWAN)
Wide area application services
Wireless WAN
References
External links
Cisco - Introduction to WAN Technologies
What is a software-defined wide area network?
Wide area networks
Telecommunications
Data transmission | Wide area network | Technology | 1,235 |
2,225,997 | https://en.wikipedia.org/wiki/C%20Traps%20and%20Pitfalls | C Traps and Pitfalls is a slim computer programming book by former AT&T Corporation researcher and programmer Andrew Koenig, its first edition still in print in 2017, which outlines the many ways in which beginners and even sometimes quite experienced C programmers can write poor, malfunctioning and dangerous source code.
It evolved from an earlier technical report, by the same name, published internally at Bell Labs. This, in turn was inspired by a prior paper given by Koenig on "PL/I Traps and Pitfalls" at a SHARE conference in 1977. Koenig wrote that this title was inspired by a 1968 science fiction anthology by Robert Sheckley, "The People Trap and other Pitfalls, Snares, Devices and Delusions, as Well as Two Sniggles and a Contrivance".
References
1989 non-fiction books
Computer programming books
Software bugs
C (programming language)
Software anomalies
Addison-Wesley books | C Traps and Pitfalls | Technology | 193 |
215,255 | https://en.wikipedia.org/wiki/Abducens%20nerve | The abducens nerve or abducent nerve, also known as the sixth cranial nerve, cranial nerve VI, or simply CN VI, is a cranial nerve in humans and various other animals that controls the movement of the lateral rectus muscle, one of the extraocular muscles responsible for outward gaze. It is a somatic efferent nerve.
Structure
Nucleus
The abducens nucleus is located in the pons, on the floor of the fourth ventricle, at the level of the facial colliculus. Axons from the facial nerve loop around the abducens nucleus, creating a slight bulge (the facial colliculus) that is visible on the dorsal surface of the floor of the fourth ventricle. The abducens nucleus is close to the midline, like the other motor nuclei that control eye movements (the oculomotor and trochlear nuclei).
Motor axons leaving the abducens nucleus run ventrally and caudally through the pons. They pass lateral to the corticospinal tract (which runs longitudinally through the pons at this level) before exiting the brainstem at the pontomedullary junction.
Course
The abducens nerve emerges from the brainstem at the junction of the pons and the medulla, superior to the medullary pyramid, and medial to the facial nerve. It runs upwards and forwards from this position to reach the eye.
The nerve enters the subarachnoid space (more precisely, the pontine cistern) when it emerges from the brainstem. It runs upward between the pons and the clivus, and then pierces the dura mater to run between the dura and the skull through Dorello's canal. At the apex of the petrous part of the temporal bone, it makes a sharp turn forward to enter the cavernous sinus. In the cavernous sinus, it runs anterior-ward alongside (inferolateral to) the internal carotid artery. It enters the orbit through (medial end of) the superior orbital fissure, passing through the common tendinous ring to reach and innervate the lateral rectus muscle of the eye.
Development
The human abducens nerve is derived from the basal plate of the embryonic pons.
Function
The abducens nerve supplies the lateral rectus muscle of the human eye. This muscle is responsible for outward gaze. The abducens nerve carries axons of type GSE, general somatic efferent.
Clinical significance
Damage
Damage to the peripheral part of the abducens nerve will cause double vision (diplopia), due to the unopposed muscle tone of the medial rectus muscle. The affected eye is pulled to look towards the midline. In order to see without double vision, patients will rotate their heads so that both eyes are toward the temple. Partial damage to the abducens nerve causes weak or incomplete abduction of the affected eye. The diplopia is worse on attempts at looking laterally.
The long course of the abducens nerve between the brainstem and the eye makes it vulnerable to injury at many levels. For example, fractures of the petrous temporal bone can selectively damage the nerve, as can aneurysms of the intracavernous carotid artery. Mass lesions that push the brainstem downward can damage the nerve by stretching it between the point where it emerges from the pons and the point where it hooks over the petrous temporal bone.
The central anatomy of the sixth nerve predicts (correctly) that infarcts affecting the dorsal pons at the level of the abducens nucleus can also affect the facial nerve, producing an ipsilateral facial palsy together with a lateral rectus palsy. The anatomy also predicts (correctly) that infarcts involving the ventral pons can affect the sixth nerve and the corticospinal tract simultaneously, producing a lateral rectus palsy associated with a contralateral hemiparesis. These rare syndromes are of interest primarily as useful summaries of the anatomy of the brainstem.
Peripheral lesions
Complete interruption of the peripheral sixth nerve causes diplopia (double vision), due to the unopposed action of the medial rectus muscle. The affected eye is pulled medially. In order to see without double vision, patients will turn their heads sideways so that both eyes are looking sideways. On formal testing, the affected eye cannot abduct past the midline – it cannot look sideways, toward the temple. Partial damage to the sixth nerve causes weak or incomplete abduction of the affected eye. The diplopia is worse on attempted lateral gaze, as would be expected (since the lateral gaze muscle is impaired).
Peripheral sixth nerve damage can be caused by tumors, aneurysms, or fractures – anything that directly compresses or stretches the nerve. Other processes that can damage the sixth nerve include strokes (infarctions), demyelination, infections (e.g. meningitis), cavernous sinus diseases and various neuropathies. Perhaps the most common overall cause of sixth nerve impairment is diabetic neuropathy. Iatrogenic injury is also known to occur, with the abducens nerve being the most commonly injured cranial nerve in halo orthosis placement. The resultant palsy is identified through loss of lateral gaze after application of the orthosis.
Rare causes of isolated sixth nerve damage include Wernicke–Korsakoff syndrome and Tolosa–Hunt syndrome. Wernicke–Korsakoff syndrome is caused by thiamine deficiency, classically due to alcoholism. The characteristic ocular abnormalities are nystagmus and lateral rectus weakness. Tolosa-Hunt syndrome is an idiopathic granulomatous disease that causes painful oculomotor (especially sixth nerve) palsies.
Indirect damage to the sixth nerve can be caused by any process (brain tumor, hydrocephalus, pseudotumor cerebri, hemorrhage, edema) that exerts downward pressure on the brainstem, causing the nerve to stretch along the clivus. This type of traction injury can affect either side first. A right-sided brain tumor can produce either a right-sided or a left-sided sixth nerve palsy as an initial sign. Thus a right-sided sixth nerve palsy does not necessarily imply a right-sided cause. Sixth nerve palsies are infamous as "false localizing signs." Neurological signs are described as "false localizing" if they reflect dysfunction distant or remote from the expected anatomical location of pathology. Isolated sixth nerve palsies in children are assumed to be due to brain tumors until proven otherwise.
Nuclear lesions
Damage to the abducens nucleus does not produce an isolated sixth nerve palsy, but rather a horizontal gaze palsy that affects both eyes simultaneously. The abducens nucleus contains two types of cells: motor neurons that control the lateral rectus muscle on the same side, and interneurons that cross the midline and connect to the contralateral oculomotor nucleus (which controls the medial rectus muscle of the opposite eye). In normal vision, lateral movement of one eye (lateral rectus muscle) is precisely coupled to medial movement of the other eye (medial rectus muscle), so that both eyes remain fixed on the same object.
The control of conjugate gaze is mediated in the brainstem by the medial longitudinal fasciculus (MLF), a nerve tract that connects the three extraocular motor nuclei (abducens, trochlear and oculomotor) into a single functional unit. Lesions of the abducens nucleus and the MLF produce observable sixth nerve problems, most notably internuclear ophthalmoplegia (INO).
Supranuclear lesions
The sixth nerve is one of the final common pathways for numerous cortical systems that control eye movement in general. Cortical control of eye movement (saccades, smooth pursuit, accommodation) involves conjugate gaze, not unilateral eye movement.
Tuberculosis
15–40% of people with tuberculosis have some resulting cranial nerve deficit. The sixth nerve is the most commonly affected cranial nerve in immunocompetent people with tuberculosis.
History
Etymology
The Latin name for the sixth cranial nerve is "nervus abducens". The Terminologia Anatomica officially recognizes two different English translations: "abducent nerve" and "abducens nerve".
"Abducens" is more common in recent literature, while "abducent" predominates in the older literature. The United States National Library of Medicine uses "abducens nerve" in its Medical Subject Heading (MeSH) vocabulary to index the vast MEDLINE and PubMed biomedical databases. The 39th edition of Gray's Anatomy (2005) also prefers "abducens nerve."
Other animals
The abducens nerve controls the movement of a single muscle, the lateral rectus muscle of the eye. In most other mammals it also innervates the musculus retractor bulbi, which can retract the eye for protection. Homologous abducens nerves are found in all vertebrates except lampreys and hagfishes.
See also
References
Blumenfeld H. Neuroanatomy Through Clinical Cases. Sinauer Associates, 2002
Brodal A. Neurological Anatomy in Relation to Clinical Medicine, 3rd ed. Oxford University Press, 1981
Brodal P. The Central Nervous System, 3rded. Oxford University Press, 2004
Butler AB, Hodos W. Comparative Vertebrate Neuroanatomy, 2nd ed. Wiley-Interscience, 2005
Carpenter MB. Core Text of Neuroanatomy, 4th ed. Williams & Wilkins, 1991.
Kandel ER, Schwartz JH, Jessell TM. Principles of Neural Science, 4th ed. McGraw-Hill, 2000
Martin JH. Neuroanatomy Text and Atlas, 3rd ed. McGraw-Hill, 2003.
Patten J. Neurological Differential Diagnosis, 2nd ed. Springer, 1996.
Victor, M, Ropper, AH. Adam's and Victor's Principles of Neurology, 7th ed. McGraw-Hill, 2001.
Wilson-Pauwels L, Akesson EJ, Stewart PA. Cranial Nerves: Anatomy and Clinical Comments. Decker, 1998.
Books
Additional images
External links
Animations of extraocular cranial nerve and muscle function and damage (University of Liverpool)
()
Cranial nerves
Otorhinolaryngology
Human head and neck
Nervous system
Neurology
Nerves of the head and neck
Ophthalmology | Abducens nerve | Biology | 2,203 |
26,342,713 | https://en.wikipedia.org/wiki/MusiXTeX | MusiXTeX is a suite of open source music engraving macros and fonts that allow music typesetting in TeX, released under the GPL-2.0-or-later license.
History
Macros for typesetting music in TeX first appeared in 1987 (MuTeX) and were limited to one-staff systems.
In 1991, Daniel Taupin created MusicTeX, whose macros allowed the production of systems with multiple staves, but which presented a few problems in controlling the horizontal positioning of notes. MusicTeX used a one-pass compilation.
In 1997 the positioning problems were corrected in MusiXTeX, which includes the external application musixflx to control the horizontal distances. This new module requires a three-pass compilation: TeX, musixflx and TeX again. MusiXTeX requires ghostscript.
Three-pass system
When compiling a TeX source file named file.tex, a file.mx1 is generated, containing information about the distances between staves and bar lengths. This file is processed by the program musixflx, which determines the distances between notes for each beat and writes them in file.mx2, which is used in compiling the final TeX file. Any changes in the score that affect the horizontal distances require file.mx2 to be deleted and all three passes to be performed again; otherwise, only one compilation in TeX is required.
Spin-offs
In 1996, Han-Wen Nienhuys and Jan Nieuwenhuizen, who were working in the MusiXTeX PreProcessor (MPP) project since the previous year, decided to create a new music engraving program loosely based on MusiXTeX's concepts, named LilyPond. LilyPond 1.0 was released on 31 July 1998, highlighting the development of a custom music font, Feta, and the complete separation of LilyPond from MusiXTeX.
PMX is a preprocessor for MusiXTeX written by Don Simons.
See also
List of music software
List of TeX extensions
References
External links
MusiXTeX and Related Software
List of programs that import/export to the MusiXTeX format
TeX
Scorewriters
Scorewriters for Linux | MusiXTeX | Mathematics,Technology | 458 |
53,102,766 | https://en.wikipedia.org/wiki/Hemicordulia%20novaehollandiae | Hemicordulia novaehollandiae is not formally recognized as a species of dragonfly by collections in Australia. It was originally described as being in the family Corduliidae from Nouvelle-Hollande (Australia) in 1871 by Edmond de Sélys-Longchamps, and the location of the holotype is unknown.
References
Corduliidae
Insects described in 1871
Nomina dubia | Hemicordulia novaehollandiae | Biology | 82 |
15,093,076 | https://en.wikipedia.org/wiki/Lunar%20Expeditionary%20Complex | The LEK Lunar Expeditionary Complex was a lunar expedition and Moon base proposed by Valentin Glushko in 1974 as a Soviet response to the United States' Apollo program and as a successor to the Zvezda moonbase, which was based on the cancelled N1-L3 crewed Moon expedition program. If implemented, it was intended to have been operational by 1980 and used for scientific and engineering research.
Hardware
The Vulkan-LEK project was based on new superheavy launcher developed in Glushko's bureau.
The moonbase design consisted of a number of modules, including:
Lunokhod, an 8-ton pressurized lunar rover to be used to build the base and for expeditions.
The LZM ("Laboratory-Factory Module"), a 15.5-ton pressurized module to be used for oxygen production and scientific experiments.
The LZhM ("Laboratory-Habitation Module"), 21.5-ton habitation module where cosmonauts were to reside.
A nuclear power station to provide electricity.
A simple transport vehicle to ferry supplies to and from a lunar orbit.
Project termination
The project was cancelled in 1976 when a Russian Academy of Sciences Commission ruled that resources should be targeted toward projects primarily adding economic value rather than for national prestige.
See also
Zvezda (moonbase)
Soviet Moonshot
Space race
References
External links
the LEK Lunar Expeditionary Complex at astronautix.com.
Entry at russianspaceweb.com.
Colonization of the Moon
Soviet lunar program | Lunar Expeditionary Complex | Astronomy | 311 |
10,370,738 | https://en.wikipedia.org/wiki/Utah%20statistical%20areas | The U.S. currently has 12 statistical areas that have been delineated by the Office of Management and Budget (OMB). On July 21, 2023, the OMB delineated one combined statistical area, five metropolitan statistical areas, and six micropolitan statistical areas in Utah. As of 2023, the largest of these is the Salt Lake City-Provo-Orem, UT-ID CSA, anchored by Utah's capital and largest city, Salt Lake City.
Table
Primary statistical areas
Primary statistical areas (PSAs) include all combined statistical areas and any core-based statistical area that is not a constituent of a combined statistical area. Of the 12 statistical areas of Utah, seven are PSAs comprising one combined statistical area, two metropolitan statistical areas and four micropolitan statistical areas.
See also
Geography of Utah
Demographics of Utah
Notes
References
External links
Office of Management and Budget
United States Census Bureau
United States statistical areas
Statistical Areas Of Utah
Statistical Areas Of Utah
Statistical Areas Of Utah | Utah statistical areas | Mathematics | 204 |
43,871,397 | https://en.wikipedia.org/wiki/Coin%20of%20the%20Year%20Award | The Coin of the Year Award (COTY) is an awards program founded and annually conducted by the American publisher Krause Publications of Iola, Wisconsin, and directed at the coin producing industry. Awards are given for numismatic design, artistic vision and craftsmanship. A panel of international judges chooses the coins from those issued two years prior to the year of the award.
About
The COTY was awarded for the first time in 1984, in which coins issued in 1982 were assessed. A panel of judges chooses ten coins to be nominees for each of ten categories. These nominees will then be reviewed by an international panel of judges who are numismatic experts, journalist, authors, coin designers, and mint, bank and museum officials. Category winners are selected in the first round of voting and Coin of the Year in the second round, chosen from the category winners.
Categories
Awards are currently given in ten categories. When the awards were first started, there were six categories. Five categories have since been added and one was dropped.
Best Bi-metallic: (1995–present) Bi-metallic coins are composed of two metals which can be seen, generally one metal in an outer ring and one in the inner ring.
Best Contemporary Event: (1996–present) Coins which commemorate events, institutions physical entities, or individuals which are deemed to be most important in terms of current or recent events influencing a people or mankind.
Best Crown: Coins which have all-around aesthetic and commercial appeal, and have a minimum diameter of 33mm.
Best Circulating: (1987–present) Circulating monetary unit coins which are made of non-precious metals, possess all-around aesthetic and commercial appeal.
Best Gold: Coins fabricated of gold, platinum, Palladium, or another exotic precious metal which have all-around aesthetic and commercial appeal.
Best Silver: Coins fabricated of silver which have all-around aesthetic and commercial appeal.
Most Popular: (1986-2013) Coins with commercial sales and artistic caliber which appeals to the general public internationally.
Most Artistic: Coins selected solely on the value of their artistic merit.
Most Historically Significant: Coins which commemorate events, institutions, physical entities, or individual which are deemed to be most important in terms of the historical heritage of a people or mankind.
Most Innovative: (1990–present) Coins which contain pioneering metallic alloys, non-typical coinage materials, planchet shapes, thickness, sizes, themes, distribution methods or other innovations.
Most Inspirational: (1995–present) Coins featuring themes, events, institutions, physical entities, or individuals that represent peace, freedom, and human rights.
List of award winners
2023 (minted in 2021)
2022 (minted in 2020)
Reference and images:
2021 (minted in 2019)
Reference and images:
2020 (minted in 2018)
Reference and images:
2019 (minted in 2017)
Reference and images:
2018 (minted in 2016)
Reference and images:
2017 (minted in 2015)
Reference and images:
2016 (minted in 2014)
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2015 (minted in 2013)
Reference and images:
2014 (minted in 2012)
Reference and images:
2013 (minted in 2011)
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2012 (minted in 2010)
Reference and images:
2011 (minted in 2009)
2010 (minted in 2008)
2009 (minted in 2007)
2008 (minted in 2006)
2007 (minted in 2005)
2006 (minted in 2004)
2005 (minted in 2003)
2004 (minted in 2002)
2003 (minted in 2001)
2002 (minted in 2000)
2001 (minted in 1999)
2000 (minted in 1998)
1999 (minted in 1997)
1998 (minted in 1996)
1997 (minted in 1995)
1996 (minted in 1994)
1995 (minted in 1993)
1994 (minted in 1992)
1993 (minted in 1991)
1992 (minted in 1990)
1991 (minted in 1989)
1990 (minted in 1988)
1989 (minted in 1987)
1988 (minted in 1986)
1987 (minted in 1985)
1986 (minted in 1984)
1985 (minted in 1983)
1984 (minted in 1982)
References
General
Specific
Coins
Arts awards in the United States
Design awards
Awards established in 1984
Lists of awards
Awards for numismatics | Coin of the Year Award | Engineering | 879 |
49,964,955 | https://en.wikipedia.org/wiki/Herman%20van%20Bekkum | Herman van Bekkum (26 September 1932 – 30 November 2020) was a Dutch organic chemist. He was professor of Catalysis in Organic Chemistry between 1971 and 1998 at Delft University of Technology. He served as rector magnificus of the university between 1975 and 1976. He was an expert in the field of carbohydrate chemistry and zeolites.
Career
Van Bekkum was born on 26 September 1932 in Rotterdam. He studied technological chemistry at Delft University of Technology and graduated in 1959. He subsequently worked two years for Royal Dutch Shell before returning to Delft University to work as lecturer. In 1971 he was named professor of Catalysis in Organic Chemistry. From 1975 to 1976 he served as rector magnificus of the university. As professor van Bekkum specialized in carbohydrate chemistry and the study of zeolites. In 1995 van Bekkum was appointed as the first president of the newly-founded Federation of the European Zeolite Association.
In 1998 he officially retired, however, by 2013 he was still working at the university. In his period at Delft University van Bekkum was doctoral advisor to 75 students.
Van Bekkum was elected member of the Royal Netherlands Academy of Arts and Sciences in 1995. He became an honorary member of the Royal Netherlands Chemical Society in 1998.
Apart from his career in chemistry van Bekkum was a competitive chess player.
He died on 30 November 2020 in Rotterdam, at age 88.
References
1932 births
2020 deaths
Delft University of Technology alumni
Academic staff of the Delft University of Technology
20th-century Dutch chemists
Dutch chess players
Members of the Royal Netherlands Academy of Arts and Sciences
Organic chemists
Scientists from Rotterdam
Rectors of universities in the Netherlands | Herman van Bekkum | Chemistry | 355 |
54,223 | https://en.wikipedia.org/wiki/Creator%20deity | A creator deity or creator god is a deity responsible for the creation of the Earth, world, and universe in human religion and mythology. In monotheism, the single God is often also the creator. A number of monolatristic traditions separate a secondary creator from a primary transcendent being, identified as a primary creator.
Monotheism
Atenism
Initiated by Pharaoh Akhenaten and Queen Nefertiti around 1330 BCE, during the New Kingdom period in ancient Egyptian history. They built an entirely new capital city (Akhetaten) for themselves and worshippers of their sole creator god in a wilderness. His father used to worship Aten alongside other gods of their polytheistic religion. Aten, for a long time before his father's time, was revered as a god among the many gods and goddesses in Egypt. Atenism was countermanded by later pharaoh Tutankhamun, as chronicled in the artifact, the Restoration Stela. Despite different views, Atenism is considered by some scholars to be one of the frontiers of monotheism in human history.
Abrahamic religions
Judaism
The Genesis creation narrative is the creation myth of both Judaism and Christianity. The narrative is made up of two stories, roughly equivalent to the first two chapters of the Book of Genesis. In the first, Elohim (the Hebrew generic word for God) creates the heavens and the Earth, the animals, and mankind in six days, then rests on, blesses and sanctifies the seventh (i.e. the Biblical Sabbath). In the second story, God, now referred to by the personal name Yahweh, creates Adam, the first man, from dust and places him in the Garden of Eden, where he is given dominion over the animals. Eve, the first woman, is created from Adam and as his companion.
It expounds themes parallel to those in Mesopotamian mythology, emphasizing the Israelite people's belief in one God. The first major comprehensive draft of the Pentateuch (the series of five books which begins with Genesis and ends with Deuteronomy) was composed in the late 7th or the 6th century BCE (the Jahwist source) and was later expanded by other authors (the Priestly source) into a work very similar to Genesis as known today. The two sources can be identified in the creation narrative: Priestly and Jahwistic. The combined narrative is a critique of the Mesopotamian theology of creation: Genesis affirms monotheism and denies polytheism. Robert Alter described the combined narrative as "compelling in its archetypal character, its adaptation of myth to monotheistic ends".
Christianity
The Abrahamic creation narrative is made up of two stories, roughly equivalent to the two first chapters of the Book of Genesis. The first account (1:1 through 2:3) employs a repetitious structure of divine fiat and fulfillment, then the statement "And there was evening and there was morning, the [xth] day," for each of the six days of creation. In each of the first three days there is an act of division: day one divides the darkness from light, day two the "waters above" from the "waters below", and day three the sea from the land. In each of the next three days these divisions are populated: day four populates the darkness and light with sun, moon, and stars; day five populates seas and skies with fish and fowl; and finally, land-based creatures and mankind populate the land.
The first (the Priestly story) was concerned with the cosmic plan of creation, while the second (the Yahwist story) focuses on man as cultivator of his environment and as a moral agent. The second account, in contrast to the regimented seven-day scheme of Genesis 1, uses a simple flowing narrative style that proceeds from God's forming the first man through the Garden of Eden to the creation of the first woman and the institution of marriage. In contrast to the omnipotent God of Genesis 1 creating a god-like humanity, the God of Genesis 2 can fail as well as succeed. The humanity he creates is not god-like, but is punished for acts which would lead to their becoming god-like (Genesis 3:1-24) and the order and method of creation itself differs. "Together, this combination of parallel character and contrasting profile point to the different origin of materials in Genesis 1:1 and Gen 2:4, however elegantly they have now been combined."
An early conflation of Greek philosophy with the narratives in the Hebrew Bible came from Philo of Alexandria (d. 50 CE), writing in the context of Hellenistic Judaism. Philo equated the Hebrew creator-deity Yahweh with Aristotle's unmoved mover (First Cause) in an attempt to prove that the Jews had held monotheistic views even before the Greeks.
A similar theoretical proposition was demonstrated by Thomas Aquinas, who linked Aristotelian philosophy with the Christian faith, followed by the statement that God is the First Being, the First Mover, and is Pure Act.
The deuterocanonical 2 Maccabees has two relevant passages. At chapter 7, it narrows about the mother of a Jewish proto-martyr telling to her son: "I beseech thee, my son, look upon heaven and earth, and all that is in them: and consider that God made them out of nothing, and mankind also"; at chapter 1, it refers a solemn prayer hymned by Jonathan, Nehemiah and the Priest of Israel, while making sacrifices in honour of God: "O Lord, Lord God, Creator of all things, who art fearefull, and strong, and righteous, and mercifull, and the onely, and gracious king".
The Prologue to the Gospel of John begins with: "In the beginning was the Word, and the Word was with God, and the Word was God. 2 The same was in the beginning with God. 3 All things were made by him, and without him was not any thing made that was made."
Christianity affirms the creation by God since its early time in the Apostles' Creed ("I believe in God, the Father almighty, creator of heaven and earth.", 1st century CE), that is symmetrical to the Nicene Creed (4th century CE).
Nowadays, theologians debate whether the Bible itself teaches if this creation by God is a creation ex nihilo. Traditional interpreters argue on grammatical and syntactical grounds that this is the meaning of Genesis 1:1, which is commonly rendered: "In the beginning God created the heavens and the earth." However, other interpreters understand creation ex nihilo as a 2nd-century theological development. According to this view, church fathers opposed notions appearing in pre-Christian creation myths and in Gnosticism—notions of creation by a demiurge out of a primordial state of matter (known in religious studies as chaos after the Greek term used by Hesiod in his Theogony).
Jewish thinkers took up the idea, which became important to Judaism.
Islam
According to Islam, the creator deity, God, known as Allah, is the all-powerful and all-knowing Creator, Sustainer, Ordainer, and Judge of the universe. Creation is seen as an act of divine choice and mercy, one with a grand purpose: "And We did not create the heaven and earth and that between them in play." Rather, the purpose of humanity is to be tested: "Who has created death and life, that He may test you which of you is best in deed. And He is the All-Mighty, the Oft-Forgiving;" Those who pass the test are rewarded with Paradise: "Verily for the Righteous there will be a fulfilment of (the heart's) desires;"
According to the Islamic teachings, God exists above the heavens and the creation itself. The Quran mentions, "He it is Who created for you all that is on earth. Then He Istawa (rose over) towards the heaven and made them seven heavens and He is the All-Knower of everything." At the same time, God is unlike anything in creation: "There is nothing like unto Him, and He is the Hearing, the Seeing." and nobody can perceive God in totality: "Vision perceives Him not, but He perceives [all] vision; and He is the Subtle, the Acquainted." God in Islam is not only majestic and sovereign, but also a personal God: "And indeed We have created man, and We know what his ownself whispers to him. And We are nearer to him than his jugular vein (by Our Knowledge)." Allah commands the believers to constantly remember Him ("O you who have believed, remember Allah with much remembrance") and to invoke Him alone ("And whoever invokes besides Allah another deity for which he has no proof—then his account is only with his Lord. Indeed, the disbelievers will not succeed.").
Islam teaches that God as referenced in the Qur'an is the only god and the same God worshipped by members of other Abrahamic religions such as Christianity and Judaism.
Sikhism
One of the biggest responsibilities in the faith of Sikhism is to worship God as "The Creator", termed Waheguru, who is shapeless, timeless, and sightless, i.e., Nirankar, Akal, and Alakh Niranjan. The religion only takes after the belief in "One God for All" or Ik Onkar.
Baháʼí Faith
In the Baháʼí Faith God is the imperishable, uncreated being who is the source of all existence. He is described as "a personal God, unknowable, inaccessible, the source of all Revelation, eternal, omniscient, omnipresent and almighty". Although transcendent and inaccessible directly, his image is reflected in his creation. The purpose of creation is for the created to have the capacity to know and love its creator.
Mandaeism
In Mandaeism, Hayyi Rabbi (lit=The Great Life), or 'The Great Living God', is the supreme God from which all things emanate. He is also known as 'The First Life', since during the creation of the material world, Yushamin emanated from Hayyi Rabbi as the "Second Life." "The principles of the Mandaean doctrine: the belief of the only one great God, Hayyi Rabbi, to whom all absolute properties belong; He created all the worlds, formed the soul through his power, and placed it by means of angels into the human body. So He created Adam and Eve, the first man and woman." Mandaeans recognize God to be the eternal, creator of all, the one and only in domination who has no partner.
Monolatrism
Monolatristic traditions would separate a secondary creator from the primary transcendent being, identified as a primary creator. According to Gaudiya Vaishnavas, Brahma is the secondary creator and not the supreme. Vishnu is the primary creator. According to Vaishnava belief Vishnu creates the basic universal shell and provides all the raw materials and also places the living entities within the material world, fulfilling their own independent will. Brahma works with the materials provided by Vishnu to actually create what are believed to be planets in Puranic terminology, and he supervises the population of them.
Monism
Monism is the philosophy that asserts oneness as its fundamental premise, and it contradicts the dualism-based theistic premise that there is a creator God that is eternal and separate from the rest of existence. There are two types of monism, namely spiritual monism which holds that all spiritual reality is one, and material monism which holds that everything including all material reality is one and the same thing.
Non-creationism
Buddhism
Buddhism denies a creator deity and posits that mundane deities such as Mahabrahma are misperceived to be a creator.
Jainism
Jainism does not support belief in a creator deity. According to Jain doctrine, the universe and its constituents—soul, matter, space, time, and principles of motion have always existed (a static universe similar to that of Epicureanism and steady state cosmological model). All the constituents and actions are governed by universal natural laws. It is not possible to create matter out of nothing and hence the sum total of matter in the universe remains the same (similar to law of conservation of mass). Similarly, the soul of each living being is unique and uncreated and has existed since beginningless time.
The Jain theory of causation holds that a cause and its effect are always identical in nature and therefore a conscious and immaterial entity like God cannot create a material entity like the universe. Furthermore, according to the Jain concept of divinity, any soul who destroys its karmas and desires achieves liberation. A soul who destroys all its passions and desires has no desire to interfere in the working of the universe. Moral rewards and sufferings are not the work of a divine being, but a result of an innate moral order in the cosmos; a self-regulating mechanism whereby the individual reaps the fruits of his own actions through the workings of the karmas.
Through the ages, Jain philosophers have adamantly rejected and opposed the concept of creator and omnipotent God and this has resulted in Jainism being labeled as nāstika darsana or atheist philosophy by the rival religious philosophies. The theme of non-creationism and absence of omnipotent God and divine grace runs strongly in all the philosophical dimensions of Jainism, including its cosmology, karma, moksa and its moral code of conduct. Jainism asserts a religious and virtuous life is possible without the idea of a creator god.
Polytheism
In polytheistic creation, the world often comes into being organically, e.g. sprouting from a primal seed, sexually, by miraculous birth (sometimes by parthenogenesis), by hieros gamos, violently, by the slaying of a primeval monster, or artificially, by a divine demiurge or "craftsman". Sometimes, a god is involved, wittingly or unwittingly, in bringing about creation. Examples include:
Sub-Saharan African contexts:
Mbombo of Bakuba mythology, who vomited out the world upon feeling a stomachache
in Zulu mythology
American contexts:
(Great Rabbit), Ojibwe deity, a shape-shifter and a cocreator of the world
in Aztec mythology
(and/or Bague) in Muisca mythology
in cosmology of the O'odham peoples
Viracocha in Inca mythology
A trickster deity in the form of a Raven in Inuit mythology
Near Eastern contexts:
Egyptian mythology
Atum in Ennead, whose semen becomes the primal component of the universe
Ptah creating the universe by the Word
Neith, who wove all of the universe and existence into being on her loom.
in Canaanite religion
killing in the Babylonian
Asian contexts:
Atingkok Maru Sidaba in Manipuri mythology, the creator of the universe
in Mongolian mythology, king of the skies
Eskeri - in Tungusic mythology
in Ainu mythology, who built the world on the back of a trout
and in Japanese mythology, who churned the ocean with a spear, creating the islands of Japan
in Chinese mythology, he is the one who separated heaven and earth and became geographic features such as mountains and rivers
the god who created the world in Vietnamese mythology
European contexts:
The sons of slaying the primeval giant in Norse mythology
in Slavic mythology
or (Radien Father) in Sámi mythology
Oceanic contexts:
, creator of humanity, the god of fertility and the chief god of the "" or "bird-man" cult of Rapa Nui mythology.
, the Sky Father, and , the Earth Mother in Māori mythology
Platonic demiurge
Plato, in his dialogue Timaeus, describes a creation myth involving a being called the demiurge ( "craftsman"). Neoplatonism and Gnosticism continued and developed this concept. In Neoplatonism, the demiurge represents the second cause or dyad, after the monad. In Gnostic dualism, the demiurge is an imperfect spirit and possibly an evil being, transcended by divine Fullness (Pleroma). Unlike the Abrahamic God, Plato's demiurge is unable to create ex-nihilo.
Hinduism
Hinduism is a diverse system of thought with beliefs spanning monotheism, polytheism, panentheism, pantheism, pandeism, monism, and atheism among others; and its concept of creator deity is complex and depends upon each individual and the tradition and philosophy followed. Hinduism is sometimes referred to as henotheistic (i.e., involving devotion to a single god while accepting the existence of others), but any such term is an overgeneralization.
The Nasadiya Sukta (Creation Hymn) of the Rigveda is one of the earliest texts which "demonstrates a sense of metaphysical speculation" about what created the universe, the concept of god(s) and The One, and whether even The One knows how the universe came into being. The Rig Veda praises various deities, none superior nor inferior, in a henotheistic manner. The hymns repeatedly refer to One Truth and Reality. The "One Truth" of Vedic literature, in modern era scholarship, has been interpreted as monotheism, monism, as well as a deified Hidden Principles behind the great happenings and processes of nature.
The post-Vedic texts of Hinduism offer multiple theories of cosmogony, many involving Brahma. These include Sarga (primary creation of universe) and Visarga (secondary creation), ideas related to the Indian thought that there are two levels of reality, one primary that is unchanging (metaphysical) and other secondary that is always changing (empirical), and that all observed reality of the latter is in an endless repeating cycle of existence, that cosmos and life we experience is continually created, evolved, dissolved and then re-created. The primary creator is extensively discussed in Vedic cosmogonies with Brahman or Purusha or Devi among the terms used for the primary creator, while the Vedic and post-Vedic texts name different gods and goddesses as secondary creators (often Brahma in post-Vedic texts), and in some cases a different god or goddess is the secondary creator at the start of each cosmic cycle (kalpa, aeon).
Brahma is a "secondary creator" as described in the Mahabharata and Puranas, and among the most studied and described. Born from a lotus emerging from the navel of Vishnu, Brahma creates all the forms in the universe, but not the primordial universe itself. In contrast, the Shiva-focused Puranas describe Brahma and Vishnu to have been created by Ardhanarishvara, that is half Shiva and half Parvati; or alternatively, Brahma was born from Rudra, or Vishnu, Shiva and Brahma creating each other cyclically in different aeons (kalpa). Thus in most Puranic texts, Brahma's creative activity depends on the presence and power of a higher god.
In other versions of creation, the creator deity is the one who is equivalent to the Brahman, the metaphysical reality in Hinduism. In Vaishnavism, Vishnu creates Brahma and orders him to order the rest of universe. In Shaivism, Shiva may be treated as the creator. In Shaktism, the Great Goddess creates the Trimurti.
Other
Kongo religion
The Bakongo people traditionally believe in Nzambi Mpungu, the Creator God, whom the Portuguese compared to the Christian God during colonization. They also believe his female counterpart called Nzambici, the ancestors (bakulu) as well as guardian spirits, such as Lemba, the basimbi, bakisi and bakita. Oral tradition accounts that in the beginning, there was only a circular void (mbûngi) with no life. Nzambi Mpungu summoned a spark of fire (Kalûnga) that grew until it filled the mbûngi. When it grew too large, Kalûnga became a great force of energy and unleashed heated elements across space, forming the universe with the sun, stars, planets, etc. Because of this, Kalûnga is seen as the origin of life and a force of motion. The Bakongo believe that life requires constant change and perpetual motion. Nzambi Mpunga is also referred to as Kalûnga, the God of change. Similarities between the Bakongo belief of Kalûnga and the Big Bang Theory have been studied.
Nzambi is also said to have created two worlds. As Kalûnga filled mbûngi, it created an invisible line that divided the circle in half. The top half represents the physical world (Ku Nseke or nsi a bamôyo), while the bottom half represents the spiritual world of the ancestors (Ku Mpèmba). The Kalûnga line separates these two worlds, and all living things exists on one side or another. After creation, the line and the mbûngi circle became a river, carrying people between the worlds at birth and death. Then the process repeats and a person is reborn. A simbi (pl. bisimbi) is a water spirit that is believed to inhabit bodies of water and rocks, having the ability to guide bakulu, or the ancestors, along the Kalûnga line to the spiritual world after death. They are also present during the baptisms of African American Christians, according to Hoodoo tradition.
Chinese traditional cosmology
Pangu can be interpreted as another creator deity. In the beginning there was nothing in the universe except a formless chaos. However this chaos began to coalesce into a cosmic egg for eighteen thousand years. Within it, the perfectly opposed principles of yin and yang became balanced and Pangu emerged (or woke up) from the egg. Pangu is usually depicted as a primitive, hairy giant with horns on his head and clad in furs. Pangu set about the task of creating the world: he separated Yin from Yang with a swing of his giant axe, creating the Earth (murky Yin) and the Sky (clear Yang). To keep them separated, Pangu stood between them and pushed up the Sky. This task took eighteen thousand years, with each day the sky grew ten feet higher, the Earth ten feet wider, and Pangu ten feet taller. In some versions of the story, Pangu is aided in this task by the four most prominent beasts, namely the Turtle, the Qilin, the Phoenix, and the Dragon.
After eighteen thousand years had elapsed, Pangu was laid to rest. His breath became the wind; his voice the thunder; left eye the sun and right eye the moon; his body became the mountains and extremes of the world; his blood formed rivers; his muscles the fertile lands; his facial hair the stars and milky way; his fur the bushes and forests; his bones the valuable minerals; his bone marrows sacred diamonds; his sweat fell as rain; and the fleas on his fur carried by the wind became human beings all over the world.
The first writer to record the myth of Pangu was Xu Zheng during the Three Kingdoms period.
Shangdi is another creator deity, possibly prior to Pangu; sharing concepts similar to Abrahamic faiths.
Kazakh
According to Kazakh folk tales, Jasagnan is the creator of the world.
See also
Notes
References
Bibliography
External links
Creation myths | Creator deity | Astronomy | 4,945 |
77,703,621 | https://en.wikipedia.org/wiki/Triprene | Triprene is an insecticide that is no longer in use. It is an insect growth regulator introduced by Zoecon Corporation (now Sandoz AG) under the "Altorick" trademark, registered 1974 and not renewed, expiring in 1980. The EPA records no registration, now or past.
Triprene is nontoxic to mammals, non-carcinogenic, not a human endocrine disruptor, and not neurotoxic. To fish, it may be of moderate toxicity.
Triprene is a juvenile hormone mimic. It disrupts insects' development by endocrine disruption, causing incomplete pupation and sterile adult insects.
Effectiveness
Triprene was tested against the similar kinoprene and hydroprene. Kinoprene was the most effective against long tailed mealybug and solanum mealybug, hydroprene and triprene both needing multiple applications. All controlled coffee brown scale.
References
External links
Insecticides
Ethers
Thioesters | Triprene | Chemistry | 207 |
1,157,423 | https://en.wikipedia.org/wiki/Printronix | Printronix is an American supplier of Industrial Print Solutions, Industrial Laser Printers and line and dot matrix printers. Printronix is based in Irvine, California, and operates across 14 offices worldwide.
Products
Printronix's printers are primarily used in industrial environments for printing high-volume labels, bar-codes, invoices, manifest and bill of lading documents, delivery sheets, reports, build/broadcast sheets, green bar and bank statements.
PrintNet Enterprise Suite (PNE), a web-based application allowing administrators to network and manage all Printronix line-matrix printers from a single computer, was launched in 2007.
Printronix also offers consumables, parts, accessories, service and software.
History
Printronix was founded in 1974 by Robert A. Kleist and business partners Gordon B. Barrus and David Mayne.
Barrus realized there was a capital need for businesses to store all their data via printing, so he quit his job at Data Products and started a company he named Eikon, marketing industrial-grade printers to businesses to fulfill this need. The company was not successful and Gordon regrouped to found the startup Printronix.
In the spring of 1974, in a garage in Playa del Rey, California, seven high technology pioneers got together and started a new company.
They were Gordon Barrus (RIP), Leo Emenaker (RIP), Robert A Kleist, Dave Mayne, Ray Melissa, Rafael Patiño and Glen Radke (RIP).
Initially working out of Leo Emenaker's garage in Playa Del Rey, California, Barrus developed and invented what he christened as the P300, a 300-line-per-minute (LPM) prototype line printer series.
The company would eventually incorporate, go public on the Nasdaq, and experience great success in the ensuing years with the emergence of the personal computer.
1976: Printronix goes Public and trades on the Nasdaq
1981: Opens Holland manufacturing facility and expands global operations to Europe, Middle-East and Africa
1985: Operations expand into Asia-Pacific with the opening of the Singapore Facility
1995: Printronix enters the Indian Market and signs agreement with Wipro
1998: Expansion into the China Market
2001: Printronix acquires RJS and enters the scanner/ verifier market
2008: Acquired by Vector Capital, Printronix becomes a Private Company
2009: Printronix acquires TallyGenicom
2013: Corona Investments acquires Printronix
References
Computer companies of the United States
Computer hardware companies
Computer printer companies
Manufacturing companies based in California | Printronix | Technology | 534 |
2,936,950 | https://en.wikipedia.org/wiki/Common-pool%20resource | In economics, a common-pool resource (CPR) is a type of good consisting of a natural or human-made resource system (e.g. an irrigation system or fishing grounds), whose size or characteristics makes it costly, but not impossible, to exclude potential beneficiaries from obtaining benefits from its use. Unlike pure public goods, common pool resources face problems of congestion or overuse, because they are subtractable. A common-pool resource typically consists of a core resource (e.g. water or fish), which defines the stock variable, while providing a limited quantity of extractable fringe units, which defines the flow variable. While the core resource is to be protected or nurtured in order to allow for its continuous exploitation, the fringe units can be harvested or consumed.
Examples of a Common-Pool Resource
Common-pool goods are typically regulated and nurtured in order to prevent demand from overwhelming supply and allow for their continued exploitation. Examples of common-pool resources include forests, man-made irrigation systems, fishing grounds, and groundwater basins. For instance, fishermen have an incentive to harvest as many fish as possible because if they do not, someone else will—so without management and regulation, fish stocks soon become depleted. And while a river might supply many cities with drinking water, manufacturing plants might be tempted to pollute the river if they were not prohibited from doing so by law because someone else would bear the costs. In California, where there is a huge demand for surface water but supplies are limited, common pool problems are exacerbated because the state does not manage groundwater basins at the state level. During the 2012-2016 drought, farmers with senior water rights dating back to the 19th century could use as much water as they wanted, while cities and towns had to make drastic cutbacks to water use.
In James Bay, Quebec, the beaver was an important species for food and later commerce when the fur trade started in 1670. Amerindian groups in the area have traditionally used resources communally and have a heritage of customary laws to regulate hunting. However, in the 1920s the railroads caused a large influx of non-native trappers who took advantage of the high fur prices and the indigenous people losing control of their territories. Both non-native and native trappers contributed to the decline of the beaver population, prompting conservation laws to be enacted after 1930 and outsiders being banned from trapping in James Bay. Eventually, Amerindian communities and family territories were legally recognized, and customary laws became enforceable. This restoration of local control allowed for the beaver population to recover.
Since 1947, the Maine lobster catch has been remarkably stable despite predictions of resource collapse. The state government has regulations in place but does not limit the number of licenses. The exclusion to this CPR is done through a system of traditional fishing rights which makes it so that one needs to be accepted by the community to be able to go lobster fishing. Those in a community are restricted to fishing in the territory held by that community. This is enforced by surreptitious violence towards interlopers. Fishermen in these exclusive territories catch significantly more and larger lobsters with less effort than those in areas where territories overlap.
In the New York Bight region, a cooperative of trawl fishermen that specializes in harvesting whiting limits entry into the local fishery and establishes catch quotas among members. These quotas are based on regional market sales estimations and attempt to encourage initiative while discouraging “free-riding.” They limit entry to the whiting grounds and markets through a closed membership policy and by controlling the dock space. Due to these methods, they have access to the best whiting grounds, dominate the market during winter, and can maintain relatively high prices through supply management. The fishermen consider this type of self-regulation both flexible and effective in maintaining sustainable use.
Common property systems
A common property rights regime system (not to be confused with a common-pool resource) is a particular social arrangement regulating the preservation, maintenance, and consumption of a common-pool resource. The use of the term "common property resource" to designate a type of good has been criticized, because common-pool resources are not necessarily governed by common property protocols. Examples of common-pool resources include irrigation systems, fishing grounds, pastures, forests, water or the atmosphere. A pasture, for instance, allows for a certain amount of grazing to occur each year without the core resource being harmed. In the case of excessive grazing, however, the pasture may become more prone to erosion and eventually yield less benefit to its users. Because the core resources are vulnerable, common-pool resources are generally subject to problems of congestion, overuse, pollution, and potential destruction unless harvesting or use limits are devised and enforced.
Resource systems like pastoral areas, fishing grounds, forest areas are storage variables. Under favorable conditions, they can maximize the flow without harming the total storage volume and the entire resource system. Different from the resource system, the resource unit is the amount that an individual occupies or uses from the resource system, such as the total amount of fish caught in a fishing ground, the amount of feed consumed by livestock in pastoral areas. A resource system allows multiple people or enterprise to produce at the same time, and the process of using common-pool resources can be performed simultaneously by multiple occupants. However, the resource unit cannot be used by multiple people or enterprises at the same time.
Management
The use of many common-pool resources, if managed carefully, can be extended because the resource system forms a negative feedback loop, where the stock variable continually regenerates the fringe variable as long as the stock variable is not compromised, providing an optimum amount of consumption. However, consumption exceeding the fringe value reduces the stock variable, which in turn decreases the flow variable. If the stock variable is allowed to regenerate then the fringe and flow variables may also recover to initial levels, but in many cases the loss is irreparable.
Ownership
Common-pool resources may be owned by national, regional or local governments as public goods, by communal groups as common property resources, or by private individuals or corporations as private goods. When they are owned by no one, they are used as open access resources. Having observed a number of common pool resources throughout the world, Elinor Ostrom noticed that a number of them are governed by common property protocols — arrangements different from private property or state administration — based on self-management by a local community. Her observations contradict claims that common-pool resources must be privatized or else face destruction in the long run due to collective action problems leading to the overuse of the core resource (see also Tragedy of the commons).
Definition matrix
Common property protocols
Common property systems of management arise when users acting independently threaten the total net benefit from common-pool resource. In order to maintain the resources, protocols coordinate strategies to maintain the resource as a common property instead of dividing it up into parcels of private property. Common property systems typically protect the core resource and allocate the fringe resources through complex community norms of consensus decision-making. Common resource management has to face the difficult task of devising rules that limit the amount, timing, and technology used to withdraw various resource units from the resource system. Setting the limits too high would lead to overuse and eventually to the destruction of the core resource while setting the limits too low would unnecessarily reduce the benefits obtained by the users.
In common property systems, access to the resource is not free and common-pool resources are not public goods. While there is relatively free but monitored access to the resource system for community members, there are mechanisms in place which allow the community to exclude outsiders from using its resource. Thus, in a common property state, a common-pool resource appears as a private good to an outsider and as a common good to an insider of the community. The resource units withdrawn from the system are typically owned individually by the appropriators. A common property good is rivaled in consumption.
Analysing the design of long-enduring CPR institutions, Elinor Ostrom identified eight design principles which are prerequisites for a stable CPR arrangement:
Clearly defined boundaries
Congruence between appropriation and provision rules and local conditions
Collective-choice arrangements allowing for the participation of most of the appropriators in the decision making process
Effective monitoring by monitors who are part of or accountable to the appropriators
Graduated sanctions for appropriators who do not respect community rules
Conflict-resolution mechanisms which are cheap and easy to access
Minimal recognition of rights to organize (e.g., by the government)
In case of larger CPRs: Organisation in the form of multiple layers of nested enterprises, with small, local CPRs at their bases.
Common property systems typically function at a local level to prevent the overexploitation of a resource system from which fringe units can be extracted. In some cases, government regulations combined with tradable environmental allowances (TEAs) are used successfully to prevent excessive pollution, whereas in other cases — especially in the absence of a unique government being able to set limits and monitor economic activities — excessive use or pollution continue.
Adaptive governance
The management of common-pool resources is highly dependent upon the type of resource involved. An effective strategy at one location, or of one particular resource, may not be necessarily appropriate for another. In The Challenge of Common-Pool Resources, Ostrom makes the case for adaptive governance as a method for the management of common-pool resources. Adaptive governance is suited to dealing with problems that are complex, uncertain and fragmented, as is the management of common-pool resources. Ostrom outlines five basic protocol requirements for achieving adaptive governance. These include:
Achieving accurate and relevant information, by focusing on the creation and use of timely scientific knowledge on the part of both the managers and the users of the resource
Dealing with conflict, acknowledging the fact that conflicts will occur, and having systems in place to discover and resolve them as quickly as possible
Enhancing rule compliance, through creating responsibility for the users of a resource to monitor usage
Providing infrastructure, that is flexible over time, both to aid internal operations and create links to other resources
Encouraging adaption and change to address errors and cope with new developments
Influential factors in the management of common-pool resources
A new proposal of the management of CPR is to develop autonomous organizations that are not completely privatized and controlled by government power, which led and supervised by the community to manage common-pool resources in addition to directly through the government and the free market. There are many factors that may affect the formation and development of these kinds of autonomous organizations. Effectively identifying the influencing factors of the autonomous management system of CPRs increasing the feasibility of the system, and it is more conducive to the sustainable use of resources as well.
In general, there are four variables that are very important for local common-pool resource management: (1) characteristics of the resource; (2) characteristics of the resource-dependent group; (3) institutional model of resource management; (4) the relationship between groups, external forces, and authorities.
The government, market and interest groups are all considered as external forces that have an impact on CPR management system. Changes in market demand for CPR, in particular, technological innovation increases productivity and lowers costs, which undermines the sustainability of the management system. In order to develop more resources, resource owners may seek to change the ownership of resources in the form of cooperation with the government, privatize CPR or even cancel the protection of CPR ownership by regulations. Such institutional changes prevent the implementation of policies that are beneficial to the majority of the population, while the power of the government and bureaucracy can be abused.
The community is responsible for supervising and administering CPR under an autonomous management system, the characteristics of a community can affect how CPR is managed. (1) the size of the community. The level of cooperation decreases as the number of community members grows; (2) Allocation mechanism for CPR. Encouraging the exploitation of the least used resources and reducing the exploitation of the most used resources will effectively increase the rate of resource supply and reduce the rate of resource consumption and individual demand. (3) Group identity. When people in a community have a strong sense of group identity, it helps to manage CPR within the community.
Experimental Studies on Common Pool Resource Games
Common Pool Resource (CPR) games have been a focal point in experimental research, providing insights into the dynamics and dilemmas associated with communal resource management. A foundational work introduced a conceptual framework that elucidates the strategic content of CPR dilemmas, demonstrating how theoretical constructs, such as the Prisoner's Dilemma and coordination games, apply to these behavioral challenges. Further, field experiments involving specific ecological features of CPRs, such as water irrigation, forestry, and fisheries, have revealed the impact of various resource-specific dynamics on collective action and resource management. Additionally, a study explored the external validity of CPR laboratory experiments within the context of artisanal benthic fisheries in Chile, revealing a correlation between cooperative behaviors exhibited in laboratory settings and those in real-world co-managed and open-access fisheries. These studies collectively underscore the complexity of CPR dilemmas and highlight the nuanced interplay between individual strategies, collective action, and resource sustainability, providing a multifaceted understanding of cooperation and norm internalization in the management of communal resources.
Open access resources
In economics, open access resources are, for the most part, rivalrous, non-excludable goods. This makes them similar to common goods during times of prosperity. Unlike many common goods, open access goods require little oversight or may be difficult to restrict access. However, as these resources are first come, first served, they may be affected by the phenomenon of the tragedy of the commons. Two possibilities may follow: a common property or an open access system.
However, in a different setting, such as fishing, there will be drastically different consequences. Since fish are an open access resource, it is relatively simple to fish and profit. If fishing becomes profitable, there will be more fishers and fewer fish. Fewer fish lead to higher prices which will lead again to more fishers, as well as lower reproduction of fish. This is a negative externality and an example of problems that arise with open access goods.
See also
Carrying capacity
Common good (economics)
Commons
Enclosure
Exploitation of natural resources
Global commons
Knowledge commons
Occupancy-abundance relationship
Overexploitation
Tragedy of the commons
Tyranny of small decisions
References
Citations
Bibliography
Araral, Eduardo. (2014). Ostrom, Hardin and the Commons. A Critical Appreciation and Revisionist View. Env Science and Policy. Volume 36, Pages 1–92 (February 2014)
Acheson, James, M. (1988) The Lobster Gangs of Maine.
Anderson, Terry L., Grewell, J. Bishop (2000) "Property Rights Solutions for the Global Commons: Bottom-Up or Top-Down?" In: Duke Environmental Law & Policy Forum, Vol. X, No. 2, Spring 2000.
Baland, Jean-Marie and Jean-Philippe Platteau (1996) Halting Degradation of Natural Resources: Is There a Role for Rural Communities?
Daniels, Brigham (2007) "Emerging Commons and Tragic Institutions," Environmental Law, Vol. 37.
Hess, C. and Ostrom, E. (2003), "Ideas, Artifacts, and Facilities: Information as a Common-Pool Resource", Law and Contemporary Problems 66, S. 111–146.
Hess, C. and Ostrom, E. (2001), "Artifacts, Facilities, And Content: Information as a Common-pool Resource", Workshop in Political Theory and Policy Analysis.
Meinzen-Dick, Ruth, Esther Mwangi, Stephan Dohrn. 2006. Securing the Commons. CAPRi Policy Brief 4. Washington DC: IFPRI.
Ostrom, Elinor (2003) "How Types of Goods and Property Rights Jointly Affect Collective Action", Journal of Theoretical Politics, Vol. 15, No. 3, 239-270 (2003).
Ostrom, Elinor (1990) "Governing the Commons. The Evolution of Institutions for Collective Action". Cambridge University Press.
Ostrom, Elinor, Roy Gardner, and James Walker (1994) Rules, Games, and Common-Pool Resources. University of Michigan Press. 1994.
Rose, Carol M. (2000) "Expanding the Choices for the Global Commons: Comparing Newfangled Tradable allowance schemes to Old-Fashioned Common Property Regimes". In: Duke Environmental Law & Policy Forum, Vol. X, No. 2, Spring 2000.
Saunders, Pammela Q. (2011) "A Sea Change Off the Coast of Maine: Common Pool Resources as Cultural Property". In: Emory Law Journal, Vol. 60, No. 6, June 2011.
Thompson, Jr., Barton H. (2000) "Tragically Difficult: The Obstacles to Governing the Commons" Environmental Law 30:241.
External links
Digital Library of the Commons
Public vs. Private Goods
Market failure
Property
Environmental social science concepts | Common-pool resource | Environmental_science | 3,496 |
5,762,008 | https://en.wikipedia.org/wiki/Microbial%20genetics | Microbial genetics is a subject area within microbiology and genetic engineering. Microbial genetics studies microorganisms for different purposes. The microorganisms that are observed are bacteria and archaea. Some fungi and protozoa are also subjects used to study in this field. The studies of microorganisms involve studies of genotype and expression system. Genotypes are the inherited compositions of an organism. (Austin, "Genotype," n.d.) Genetic Engineering is a field of work and study within microbial genetics. The usage of recombinant DNA technology is a process of this work. The process involves creating recombinant DNA molecules through manipulating a DNA sequence. That DNA created is then in contact with a host organism. Cloning is also an example of genetic engineering.
Since the discovery of microorganisms by Robert Hooke and Antoni van Leeuwenhoek during the period 1665-1885 they have been used to study many processes and have had applications in various areas of study in genetics.
For example: Microorganisms' rapid growth rates and short generation times are used by scientists to study evolution. Robert Hooke and Antoni van Leeuwenhoek discoveries involved depictions, observations, and descriptions of microorganisms. Mucor is the microfungus that Hooke presented and gave a depiction of. His contribution being, Mucor as the first microorganism to be illustrated. Antoni van Leeuwenhoek’s contribution to the microscopic protozoa and microscopic bacteria yielded to scientific observations and descriptions. These contributions were accomplished by a simple microscope, which led to the understanding of microbes today and continues to progress scientists understanding.
Microbial genetics also has applications in being able to study processes and pathways that are similar to those found in humans such as drug metabolism.
Role in understanding evolution
Microbial genetics can focus on Charles Darwin's work and scientists have continued to study his work and theories by the use of microbes. Specifically, Darwin's theory of natural selection is a source used. Studying evolution by using microbial genetics involves scientists looking at evolutionary balance. An example of how they may accomplish this is studying natural selection or drift of microbes. Application of this knowledge comes from looking for the presence or absence in a variety of different ways. The ways include identifying certain pathways, genes, and functions. Once the subject is observed, scientist may compare it to a sequence of a conserved gene. The process of studying microbial evolution in this way lacks the ability to give a time scale of when the evolution took place. However, by testing evolution in this way, scientist can learn the rates and outcomes of evolution. Studying the relationship between microbes and the environment is a key component to microbial genetics evolution.
Microorganisms whose study is encompassed by microbial genetics
Bacteria
Bacteria have been on this planet for approximately 3.5 billion years, and are classified by their shape. Bacterial genetics studies the mechanisms of their heritable information, their chromosomes, plasmids, transposons, and phages.
Gene transfer systems that have been extensively studied in bacteria include genetic transformation, conjugation and transduction. Natural transformation is a bacterial adaptation for DNA transfer between two cells through the intervening medium. The uptake of donor DNA and its recombinational incorporation into the recipient chromosome depends on the expression of numerous bacterial genes whose products direct this process. In general, transformation is a complex, energy-requiring developmental process that appears to be an adaptation for repairing DNA damage.
Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells. Bacterial conjugation has been extensively studied in Escherichia coli, but also occurs in other bacteria such as Mycobacterium smegmatis. Conjugation requires stable and extended contact between a donor and a recipient strain, is DNase resistant, and the transferred DNA is incorporated into the recipient chromosome by homologous recombination. E. coli conjugation is mediated by expression of plasmid genes, whereas mycobacterial conjugation is mediated by genes on the bacterial chromosome.
Transduction is the process by which foreign DNA is introduced into a cell by a virus or viral vector. Transduction is a common tool used by molecular biologists to stably introduce a foreign gene into a host cell's genome.
Archaea
Archaea is a domain of organisms that are prokaryotic, single-celled, and are thought to have developed 4 billion years ago. "They have no cell nucleus or any other organelles inside their cells."Archaea replicate asexually in a process known as binary fission. The cell division cycle includes when chromosomes of daughter cells replicate. Because archea have a singular structure chromosome, the two daughter cells separate and cell divides. Archaea have motility include with flagella, which is a tail like structure. Archaeal chromosomes replicate from different origins of replication, producing two haploid daughter cells. " They share a common ancestor with bacteria, but are more closely related to eukaryotes in comparison to bacteria. Some Archaea are able to survive extreme environments, which leads to many applications in the field of genetics. One of such applications is the use of archaeal enzymes, which would be better able to survive harsh conditions in vitro.
Gene transfer and genetic exchange have been studied in the halophilic archaeon Halobacterium volcanii and the hyperthermophilic archaeons Sulfolobus solfataricus and Sulfolobus acidocaldarius. H. volcani forms cytoplasmic bridges between cells that appear to be used for transfer of DNA from one cell to another in either direction. When S. solfataricus and S. acidocaldarius are exposed to DNA damaging agents, species-specific cellular aggregation is induced. Cellular aggregation mediates chromosomal marker exchange and genetic recombination with high frequency. Cellular aggregation is thought to enhance species specific DNA transfer between Sulfolobus cells in order to provide increased repair of damaged DNA by means of homologous recombination. Archaea are divided into 3 subgroups which are halophiles, methanogens, and thermoacidophiles. The first group, methanogens, are archaeabacteria that live in swamps and marshes as well as in the gut of humans. They also play a major role in decay and decomposition with dead organisms. Methanogens are anaerobic organisms, which are killed when they are exposed to oxygen. The second subgroup of archaeabacteria, halophiles are organisms that are present in areas with high salt concentration like the Great Salt Lake and the Dead Sea. The third subgroup thermoacidophiles also called thermophiles, are organisms that live in acidic areas. They are present in area with low pH levels like hot springs and geyers. Most thermophiles are found in the Yellowstone National Park.
Archaeal Genetics is the study of genes that consist of single nucleus-free cells. Archaea have a single, circular chromosomes that contain multiple origins of replication for initiation of DNA synthesis. DNA replication of Archaea involves similar processes including initiation, elongation, and termination. The primase used to synthesize a RNA primer varies than in eukaryotes. The primase by archaea is highly derived version of RNA recognition motif(RRM). Archaea come from Gram positive bacteria, which both have a single lipid bilayer, which are resistant to antibiotics. Archaea are similar to mitochondria in eukaryotes in that they release energy as adenosine triphosphate (ATP) through the chemical reaction called metabolism. Some archaea known as phototrophic archaea use the sun’s energy to produce ATP. ATP synthase is used as photophosphorylation to convert chemicals into ATP.
Archaea and bacteria are structurally similar even though they are not closely related in the tree of life. The shapes of both bacteria and archaea cells vary from a spherical shape known as coccus or a rod-shape known as bacillus. They are also related with no internal membrane and a cell wall that assists the cell maintaining its shape. Even though archaeal cells have cells walls, they do not contain peptidoglycan, which means archaea do not produce cellulose or chitin. Archaea are most closely related to eukaryotes due to tRNA present in archaea, but not in bacteria. Archaea have the same ribosomes as eukaryotes that synthesize into proteins. Aside from the morphology of archaea and bacteria, there are other differences between these domains. Archaea that live in extreme and harsh environments with low pH levels such as salt lakes, oceans, and in the gut of ruminants and humans are also known as extremophiles. In contrast, bacteria are found in various areas such as plants, animals, soil, and rocks.
Fungi
Fungi can be both multicellular and unicellular organisms, and are distinguished from other microbes by the way they obtain nutrients. Fungi secrete enzymes into their surroundings, to break down organic matter. Fungal genetics uses yeast, and filamentous fungi as model organisms for eukaryotic genetic research, including cell cycle regulation, chromatin structure and gene regulation.
Studies of the fungus Neurospora crassa have contributed substantially to understanding how genes work. N. crassa is a type of red bread mold of the phylum Ascomycota. It is used as a model organism because it is easy to grow and has a haploid life cycle that makes genetic analysis simple since recessive traits will show up in the offspring. Analysis of genetic recombination is facilitated by the ordered arrangement of the products of meiosis in ascospores. In its natural environment, N. crassa lives mainly in tropical and sub-tropical regions. It often can be found growing on dead plant matter after fires.
Neurospora was used by Edward Tatum and George Beadle in their experiments for which they won the Nobel Prize in Physiology or Medicine in 1958. The results of these experiments led directly to the one gene-one enzyme hypothesis that specific genes code for specific proteins. This concept proved to be the opening gun in what became molecular genetics and all the developments that have followed from that.
Saccharomyces cerevisiae is a yeast of the phylum Ascomycota. During vegetative growth that ordinarily occurs when nutrients are abundant, S. cerevisiae reproduces by mitosis as diploid cells. However, when starved, these cells undergo meiosis to form haploid spores. Mating occurs when haploid cells of opposite mating types MATa and MATα come into contact. Ruderfer et al. pointed out that, in nature, such contacts are frequent between closely related yeast cells for two reasons. The first is that cells of opposite mating type are present together in the same acus, the sac that contains the cells directly produced by a single meiosis, and these cells can mate with each other. The second reason is that haploid cells of one mating type, upon cell division, often produce cells of the opposite mating type. An analysis of the ancestry of natural S. cerevisiae strains concluded that outcrossing occurs very infrequently (only about once every 50,000 cell divisions). The relative rarity in nature of meiotic events that result from outcrossing suggests that the possible long-term benefits of outcrossing (e.g. generation of diversity) are unlikely to be sufficient for generally maintaining sex from one generation to the next. Rather, a short-term benefit, such as meiotic recombinational repair of DNA damages caused by stressful conditions (such as starvation) may be the key to the maintenance of sex in S. cerevisiae.
Candida albicans is a diploid fungus that grows both as a yeast and as a filament. C. albicans is the most common fungal pathogen in humans. It causes both debilitating mucosal infections and potentially life-threatening systemic infections. C. albicans has maintained an elaborate, but largely hidden, mating apparatus. Johnson suggested that mating strategies may allow C. albicans to survive in the hostile environment of a mammalian host.
Among the 250 known species of aspergilli, about 33% have an identified sexual state. Among those Aspergillus species that exhibit a sexual cycle the overwhelming majority in nature are homothallic (self-fertilizing). Selfing in the homothallic fungus Aspergillus nidulans involves activation of the same mating pathways characteristic of sex in outcrossing species, i.e. self-fertilization does not bypass required pathways for outcrossing sex but instead requires activation of these pathways within a single individual. Fusion of haploid nuclei occurs within reproductive structures termed cleistothecia, in which the diploid zygote undergoes meiotic divisions to yield haploid ascospores.
Protozoa
Protozoa are unicellular organisms, which have nuclei, and ultramicroscopic cellular bodies within their cytoplasm. One particular aspect of protozoa that are of interest to human geneticists are their flagella, which are very similar to human sperm flagella.
Studies of Paramecium have contributed to our understanding of the function of meiosis. Like all ciliates, Paramecium has a polyploid macronucleus, and one or more diploid micronuclei. The macronucleus controls non-reproductive cell functions, expressing the genes needed for daily functioning. The micronucleus is the generative, or germline nucleus, containing the genetic material that is passed along from one generation to the next.
In the asexual fission phase of growth, during which cell divisions occur by mitosis rather than meiosis, clonal aging occurs leading to a gradual loss of vitality. In some species, such as the well studied Paramecium tetraurelia, the asexual line of clonally aging paramecia loses vitality and expires after about 200 fissions if the cells fail to undergo meiosis followed by either autogamy (self-fertilization) or conjugation (outcrossing) (see aging in Paramecium). DNA damage increases dramatically during successive clonal cell divisions and is a likely cause of clonal aging in P. tetraurelia.
When clonally aged P. tetraurelia are stimulated to undergo meiosis in association with either autogamy or conjugation, the progeny are rejuvenated, and are able to have many more mitotic binary fission divisions. During either of these processes the micronuclei of the cell(s) undergo meiosis, the old macronucleus disintegrates and a new macronucleus is formed by replication of the micronuclear DNA that had recently undergone meiosis. There is apparently little, if any, DNA damage in the new macronucleus, suggesting that rejuvenation is associated with the repair of these damages in the micronucleus during meiosis.
Viruses
Viruses are capsid-encoding organisms composed of proteins and nucleic acids that can self-assemble after replication in a host cell using the host's replication machinery. There is a disagreement in science about whether viruses are living due to their lack of ribosomes. Comprehending the viral genome is important not only for studies in genetics but also for understanding their pathogenic properties.
Many types of virus are capable of genetic recombination. When two or more individual viruses of the same type infect a cell, their genomes may recombine with each other to produce recombinant virus progeny. Both DNA and RNA viruses can undergo recombination.
When two or more viruses, each containing lethal genomic damage infect the same host cell, the virus genomes often can pair with each other and undergo homologous recombinational repair to produce viable progeny. This process is known as multiplicity reactivation. Enzymes employed in multiplicity reactivation are functionally homologous to enzymes employed in bacterial and eukaryotic recombinational repair. Multiplicity reactivation has been found to occur with pathogenic viruses including influenza virus, HIV-1, adenovirus simian virus 40, vaccinia virus, reovirus, poliovirus and herpes simplex virus as well as numerous Bacteriophages.
Any living organism can contract a virus by giving parasites the opportunity to grow. Parasites feed on the nutrients of another organism which allows the virus to thrive. Once the human body detects a virus, it then creates fighter cells that attack the parasite/virus; literally, causing a war within the body. A virus can affect any part of the body causing a wide range of illnesses such as the flu, the common cold, and sexually transmitted diseases. The flu is an airborne virus that travels through tiny droplets and is formally known as Influenza. Parasites travel through the air and attack the human respiratory system. People that are initially infected with this virus pass infection on by normal day to day activity such as talking and sneezing. When a person comes in contact with the virus, unlike the common cold, the flu virus affects people almost immediately. Symptoms of this virus are very similar to the common cold but much worse. Body aches, sore throat, headache, cold sweats, muscle aches and fatigue are among the many symptoms accompanied by the virus. A viral infection in the upper respiratory tract results in the common cold. With symptoms like sore throat, sneezing, small fever, and a cough, the common cold is usually harmless and tends to clear up within a week or so. The common cold is also a virus that is spread through the air but can also be passed through direct contact. This infection takes a few days to develop symptoms; it is a gradual process unlike the flu.
Applications of microbial genetics
Microbes are ideally suited for biochemical and genetics studies and have made huge contributions to these fields of science such as the demonstration that DNA is the genetic material, that the gene has a simple linear structure, that the genetic code is a triplet code, and that gene expression is regulated by specific genetic processes. Jacques Monod and François Jacob used Escherichia coli, a type of bacteria, in order to develop the operon model of gene expression, which lay down the basis of gene expression and regulation. Furthermore, the hereditary processes of single-celled eukaryotic microorganisms are similar to those in multi-cellular organisms allowing researchers to gather information on this process as well. Another bacterium which has greatly contributed to the field of genetics is Thermus aquaticus, which is a bacterium that tolerates high temperatures. From this microbe scientists isolated the enzyme Taq polymerase, which is now used in the powerful experimental technique, Polymerase chain reaction(PCR). Additionally the development of recombinant DNA technology through the use of bacteria has led to the birth of modern genetic engineering and biotechnology.
Using microbes, protocols were developed to insert genes into bacterial plasmids, taking advantage of their fast reproduction, to make biofactories for the gene of interest. Such genetically engineered bacteria can produce pharmaceuticals such as insulin, human growth hormone, interferons and blood clotting factors. These biofactories are typically much cheaper to operate and maintain than the alternative procedures of producing pharmaceuticals. They're like millions of tiny pharmaceutical machines that only require basic raw materials and the right environment to produce a large amount of product. The utilization of incorporating the human insulin gene alone has had profound impacts on the medical industry. It is thought that biofactories might be the ultimate key in reducing the price of expensive life saving pharmaceutical compounds.
Microbes synthesize a variety of enzymes for industrial applications, such as fermented foods, laboratory test reagents, dairy products (such as renin), and even in clothing (such as Trichoderma fungus whose enzyme is used to give jeans a stone washed appearance).
There is currently potential for microbes to be used as an alternative for petroleum-based surfactants. Microbial surfactants would still have the same kind of hydrophillic and hydrophobic functional groups as their petroleum-based counterparts, but they have numerous advantages over their competition. In comparison, microbial amphiphillic compounds have robust a tendency to stay functional in extreme environments such as areas with high heat or extreme ph. all while being biodegradable and less toxic to the environment. This efficient and cheap method of production could be the solution to the ever increasing global consumption of surfactants. Ironically, the application for bio-based surfactants with the most demand is the oil industry which uses surfactants in general production as well as development of specific oil compositions.
Microbes are an abundant source of lipases which have a wide variety of industrial and consumer applications. Enzymes perform a wide variety of functions inside the cells of living things, so it only makes sense that we can use them for similar purposes on a larger scale. Microbial enzymes are typically preferred for mass production due to the wide variety of functions available and their ability to be mass produced. Plant and animal enzymes are typically too expensive to be mass-produced, however this is not always the case. Especially in plants. Industrial applications of lipases generally include the enzyme as a more efficient and cost-effective catalyst in the production of commercially valuable chemicals from fats and oils, because they are able to retain their specific properties in mild easy to maintain conditions and work at an increased rate. Other already successful applications of lipolytic enzymes include the production of biofuels, polymers, non-stereoisomeric pharmaceuticals, agricultural compounds, and flavor-enhancing compounds.
In regards to industrial optimization, the benefit of the biofactory method of production is the ability to direct optimization by means of directed evolution. The efficiency and specificity of production will increase over time by imposing artificial selection. This method of improving efficiency is nothing new in agriculture, but it's a relatively new concept in industrial production. It is thought that this method will be far superior to conventional industrial methods because you have optimization on multiple fronts. The first front being that the microorganisms that make up biofactories can be evolved to our needs. The second front being the conventional method of optimization brought about by the integration of advancing technologies. This combination of conventional and biological advancement is just now becoming utilized and provides a virtually limitless number of applications.
See also
Bacterial genetics
References
Microbiology
Genetics by type of organism | Microbial genetics | Chemistry,Biology | 4,732 |
42,478,623 | https://en.wikipedia.org/wiki/Sparse%20matrix%E2%80%93vector%20multiplication | Sparse matrix–vector multiplication (SpMV) of the form is a widely used computational kernel existing in many scientific applications. The input matrix is sparse. The input vector and the output vector are dense. In the case of a repeated operation involving the same input matrix but possibly changing numerical values of its elements, can be preprocessed to reduce both the parallel and sequential run time of the SpMV kernel.
See also
Matrix–vector multiplication
General-purpose computing on graphics processing units#Kernels
References
Sparse matrices | Sparse matrix–vector multiplication | Mathematics | 106 |
27,846,134 | https://en.wikipedia.org/wiki/Alexey%20Ekimov | Alexey Ekimov or Aleksey Yekimov (; born 1945) is a Russian solid state physicist and a pioneer in nanomaterials research. He discovered the semiconductor nanocrystals known as quantum dots in 1981, while working at the Vavilov State Optical Institute. In 2023, he was awarded the Nobel Prize in Chemistry for this discovery.
Life
Early years and education
Ekimov was born in Leningrad, Soviet Union in 1945. In 1967, he graduated from the Faculty of Physics, Leningrad State University. He went on to receive his PhD in physics at the Ioffe Institute of the Russian Academy of Sciences in 1974.
Research and career
After graduation, Ekimov moved to the Vavilov State Optical Institute to conduct research. He began studying semiconductor-activated glasses, known as Schott glasses, and developing theories to explain their color. When the glasses were heated and then cooled, copper chloride crystals formed, as revealed by X-rays, creating blue colors. Smaller crystals produced bluer glass.
In 1981, Ekimov, along with Alexei A. Onushchenko, reported the discovery of quantum size effects in copper chloride nanocrystals in glass, a phenomenon known now known as quantum dots. During his time at the institute he further investigated these system and developed the theory of quantum confinement with Alexander Efros.
Since 1999, Ekimov has been living and working in the United States as a scientist for Nanocrystals Technology, a company based in New York State.
Honors and awards
Ekimov was awarded the 1975 USSR State Prize in Science and Engineering for work on electron spin orientation in semiconductors. He is co-recipient of the 2006 R. W. Wood Prize of the Optical Society of America for "discovery of nanocrystal quantum dots and pioneering studies of their electronic and optical properties" shared with Alexander Efros and Louis E. Brus.
Ekimov, Brus and Moungi Bawendi were the recipients of the 2023 Nobel Prize in Chemistry "for the discovery and synthesis of quantum dots".
Selected publications
References
External links
1945 births
Living people
Nobel laureates in Chemistry
Physical chemists
Place of birth missing (living people)
Recipients of the USSR State Prize
Russian physicists
Saint Petersburg State University alumni
Soviet physicists
Russian Nobel laureates
Nanotechnologists
20th-century Russian scientists | Alexey Ekimov | Chemistry,Materials_science | 479 |
20,838,863 | https://en.wikipedia.org/wiki/Rotten%20ice | Rotten ice is a loose term for ice that is melting or structurally disintegrating due to being honeycombed by liquid water, air, or contaminants trapped between the initial growth of ice crystals. It may appear transparent or splotchy grey, and it is generally found after spring or summer thaws, presenting a danger to those traveling or spending time in outdoor recreation. The increase of rotten ice vs. solid ice in the Arctic affects ocean-atmosphere heat transfer and year-to-year ice formation, as well as the lives of the Inuit, sea mammals such as walrus and polar bear, and the microorganisms that live inside the ice.
Rotten ice has a subtype called "candle ice", which has a columnar structure. Like other rotten ice, it poses a hazard to humans due to its lack of structure.
Properties and life cycle
Compared to solid ice, rotten ice has "high porosity and enhanced permeability." This porosity facilitates "large convective transport of nutrients, salt and heat at the onset of fall freeze-up," which Algal bloom may also contribute. It forms on open water when snowpack and ice are mixed together or when polar ice melts during the spring or summer. If saturated with water, rotten ice may look dark or transparent, similar to new black ice, but otherwise it may look grey and splotchy. Though rotten ice may appear strong, it is weak—even several feet thick may not hold a person's weight. On land, it is difficult or impossible to climb.
Rotting may begin at the top or bottom surface and occurs due to absorption of heat from the sun. In general, ice melting may accelerate due to various factors. Water from underneath the ice can erode the ice and cause it to be thinner without a sign on the surface. Runoff from upstream melting, roads (especially salted), and snow can weaken the ice, and "tree stumps, rocks and docks absorb heat from the sun, causing ice around them to melt." Ice may melt faster along shorelines. Ice under a layer of snow will be thinner and weaker due to the snow's insulating effect; a new snowfall can also warm up and melt existing ice. However, snow or snow ice may also absorb or reflect incoming solar radiation and prevent rotting until the snow is melted. Regardless of thickness, ice will be weakened by multiple freezes and thaws or layers of snow inside the ice itself. It melts more quickly than solid ice.
Certain types of bacteria in rotten ice pores produce polymer-like substances, which may influence the physical properties of the ice. A team from the University of Washington studying this phenomenon hypothesizes that the polymers may provide a stabilizing effect to the ice. However, other scientists have found algae and other microorganisms produce pigments or help create a substance, cryoconite, all of which increase rotting and further the growth of the microorganisms.
Role in climate science
In 2009, researchers studying the Beaufort Sea north of Alaska found that most of the ice present had become rotten ice, instead of thick, solid ice that had either been newly formed or present for multiple years. This decline in multiyear ice contradicted previous impressions that Arctic ice was recovering from climate change and "had implications for climate science and marine vessel transport in the Arctic." Other research has found that the increased permeability of rotten ice can "contribute to ocean–atmosphere heat transfer." Future increases of rotten ice matter influence long-term ice cover: "If the ice melts completely, then the open ocean will form new ice in the autumn. Only ice remaining at the end of summer can become second-year and subsequently multiyear ice." As rotten ice exposes more of the ocean, it also creates a feedback loop where the exposed darker ocean absorbs more heat, which melts more ice and exposes more ocean.
In the years leading up to 2015, Greenland's ice cover has decreased to "a rotten ice regime", with months of solid ice decreasing from 9 per year to 2-3, and with thickness decreasing from 6-10 feet to 7 inches by 2004. The decline of solid land ice to rotten ice strongly disrupts travel and subsistence hunting for the local Inuit, as well as travel and habitat for sea mammals. In the future, the shedding rotted or melted ice may affect coastlines of other continents via rising sea levels.
Candle ice
Candle ice (sometimes known as needle ice) is a form of rotten ice that develops in columns perpendicular to the surface of a lake or other body of water. It makes a clinking sound when the "candles" are broken apart and floating in the water, bumping up against each other. As ice from a larger surface melts, the formation of candle ice "progressively increases with time, temperature, and quantity of water melt runoff." This occurs due to the hexagonal structure of the ice crystals; minerals such as salt, as well as other contaminants, can be trapped between the crystals when they initially form, and melting will begin at these boundaries due to the trapped contaminants. No matter the thickness, it can be dangerous due to its lack of horizontal structure, which means there will be no rim to grab for any person who falls through.
See also
Polar ice cap
Sea ice
Sea ice microbial communities
Frazil ice
References
Water ice
External links
Description and video close-up of candle ice
Motion Image of Candle Ice on lake surface
Sea ice
Snow or ice weather phenomena
Weather hazards | Rotten ice | Physics | 1,141 |
7,191,018 | https://en.wikipedia.org/wiki/Intel%20Paragon | The Intel Paragon is a discontinued series of massively parallel supercomputers that was produced by Intel in the 1990s. The Paragon XP/S is a productized version of the experimental Touchstone Delta system that was built at Caltech, launched in 1992. The Paragon superseded Intel's earlier iPSC/860 system, to which it is closely related.
The Paragon series is based on the Intel i860 RISC microprocessor. Up to 2048 (later, up to 4096) i860s are connected in a 2D grid. In 1993, an entry-level Paragon XP/E variant was announced with up to 32 compute nodes.
The system architecture is a partitioned system, with the majority of the system comprising diskless compute nodes and a small number of I/O nodes interactive service nodes. Since the bulk of the nodes have no permanent storage, it is possible to "Red/Black switch" the compute partition from classified to unclassified by disconnecting one set of I/O nodes with classified disks and then connecting an unclassified I/O partition.
Intel intended the Paragon to run the OSF/1 AD distributed operating system on all processors. However, this was found to be inefficient in practice, and a light-weight kernel called SUNMOS was developed at Sandia National Laboratories to replace OSF/1 AD on the Paragon's compute processors.
Oak Ridge National Laboratory operated a Paragon XP/S 150 MP, one of the largest Paragon systems, for several years.
The prototype for the Intel Paragon was the Intel Delta, built by Intel with funding from DARPA and installed operationally at the California Institute of Technology in the late 1980s with funding from the National Science Foundation. The Delta was one of the few computers to sit significantly above the curve of Moore's Law.
Compute nodes
The computer boards was produced in two variants: the GP16 with 16 MB of memory and two CPUs, and the MP16 with three CPUs. Each node has a B-NIC interface that connects to the mesh routers on the backplane. The compute nodes are diskless and performed all I/O over the mesh. During system software development, a light-pen was duct-taped to the status LED on one board and a timer interrupt was used to bit bang a serial port.
The B-NIC ASIC is the square chip with the circular heat-sink.
I/O nodes
The IO boards have either SCSI drive interfaces or HiPPI network connections and are used to provide data to the compute nodes. They do not run any user applications. The MP64 I/O node has three i860 CPUs and an i960 CPU used in the disk controller.
References
External links
Intel products
Massively parallel computers
Supercomputers
Very long instruction word computing
32-bit computers
Intel supercomputers | Intel Paragon | Technology | 595 |
14,725,973 | https://en.wikipedia.org/wiki/EPH%20receptor%20B4 | Ephrin type-B receptor 4 is a protein that in humans is encoded by the EPHB4 gene.
Ephrin receptors and their ligands, the ephrins, mediate numerous developmental processes, particularly in the nervous system. Based on their structures and sequence relationships, ephrins are divided into the ephrin-A (EFNA) class, which are anchored to the membrane by a glycosylphosphatidylinositol linkage, and the ephrin-B (EFNB) class, which are transmembrane proteins. The Eph family of receptors are divided into 2 groups based on the similarity of their extracellular domain sequences and their affinities for binding ephrin-A and ephrin-B ligands. Ephrin receptors make up the largest subgroup of the receptor tyrosine kinase (RTK) family. The protein encoded by this gene binds to ephrin-B2 and plays an essential role in vascular development.
References
Further reading
Tyrosine kinase receptors | EPH receptor B4 | Chemistry | 219 |
43,142,928 | https://en.wikipedia.org/wiki/Protecting%20and%20Securing%20Chemicals%20Facilities%20from%20Terrorist%20Attacks%20Act%20of%202014 | The Chemical Facility Anti-Terrorism Standards Program Authorization and Accountability Act of 2014 () is a bill that proposed making permanent the United States Department of Homeland Security’s (DHS’s) authority to regulate security at certain chemical facilities in the United States. Under the Chemical Facility Anti-Terrorism Standards (CFATS) program, DHS collects and reviews information from chemical facilities in the United States to determine which facilities present security risks and then requires them to write and enact security plans.
The bill was introduced into the United States House of Representatives during the 113th United States Congress, and passed on July 8, 2014. An amended version of the bill passed the Senate on December 10 and was sent back to the House, which voted to pass on December 11. The bill was signed into law on December 18, 2014 as the Protecting and Securing Chemicals Facilities from Terrorist Attacks Act of 2014 by President Barack Obama.
Background
The Chemical Facility Anti-Terrorism Standards (CFATS), also known as 6 CFR, Part 27, are a set of US government security regulations for high-risk chemical facilities such as chemical plants, electrical generating facilities, refineries, and universities. The US Department of Homeland Security promulgated the Final Rule on April 9, 2007. The regulations came into effect on June 8, 2007, apart from material covered in Appendix A, which took effect upon its publication in the Federal Register on November 20, 2007.
The response from the US chemical community to the initial legislation was rather critical, but the revisions introduced in November appear to have addressed many of the concerns of both industry and academia. For example, certain routine chemicals of low toxicity, such as acetone or urea, have been removed from the list, since record-keeping for such common compounds was considered an excessive burden.
Provisions of the bill
This summary is based largely on the summary provided by the Congressional Research Service, a public domain source.
The Chemical Facility Anti-Terrorism Standards Program Authorization and Accountability Act of 2014 would reestablish the Chemical Facility Anti-Terrorism Standards (CFATS) Program, under which the United States Secretary of Homeland Security (DHS) is required to: (1) establish risk-based performance standards designed to protect covered chemical facilities from acts of terrorism; (2) require such facilities to submit security vulnerability assessments and develop and implement site security plans; (3) review and approve or disapprove each such assessment and plan; (4) arrange for the audit and inspection of covered chemical facilities to determine compliance with this Act; and (5) notify, and issue an order to comply to, the owner or operator of a facility not in compliance.
The bill would authorize the Secretary to: (1) issue an order assessing a civil penalty or to cease operations if an owner or operator fails to comply; and (2) approve an alternative security program established by a private sector entity or a federal, state, or local authority that meets the requirements of this Act.
The bill would authorize a covered chemical facility, in order to satisfy the requirements of a risk-based performance standard that addresses personnel surety by identifying individuals with terrorist ties, to utilize any federal screening program that periodically vets individuals against the Terrorist Screening Database.
The bill would require the Secretary to: (1) consult with the heads of other federal agencies, states and political subdivisions, and relevant business associations to identify all chemical facilities of interest; and (2) develop a risk assessment approach and corresponding tiering methodology that incorporates all relevant elements of risk, including threat, vulnerability, and consequence. Defines "covered chemical facility" to mean a chemical facility that the Secretary designates as a facility of interest and determines presents a high level of security risk, with specified exceptions.
The bill would require: (1) information developed pursuant to this Act to be protected from public disclosure, but permits the sharing of such information with state and local government officials possessing the necessary security clearances; and (2) information submitted to or obtained by the Secretary under this Act to be treated as classified material.
The bill would set forth civil penalties for violations of orders issued under this Act.
The bill would terminate this Act two years after its enactment.
Congressional Budget Office report
This summary is based largely on the summary provided by the Congressional Budget Office, as ordered reported by the House Committee on Homeland Security on April 30, 2014. This is a public domain source.
H.R. 4007 would make permanent the United States Department of Homeland Security’s (DHS’s) authority to regulate security at certain chemical facilities in the United States. Under the Chemical Facility Anti-Terrorism Standards (CFATS) program, DHS collects and reviews information from chemical facilities in the United States to determine which facilities present security risks. Facilities determined to present a high level of security risk are then required to develop a Site Security Plan (SSP). DHS in turn conducts inspections to validate the adequacy of a facility’s SSP and their compliance with it. The program is set to end on October 4, 2014.
Procedural history
The Chemical Facility Anti-Terrorism Standards Program Authorization and Accountability Act of 2014 was introduced into the United States House of Representatives on February 6, 2014 by Rep. Patrick Meehan (R, PA-7). It was referred to the United States House Committee on Homeland Security, the United States House Committee on Energy and Commerce, the United States House Homeland Security Subcommittee on Cybersecurity, Infrastructure Protection, and Security Technologies, and the United States House Energy Subcommittee on Environment and Economy. The DHS National Protection and Programs Directorate's Office of Infrastructure Protection Assistant Secretary Caitlin Durkovich testified in favor of the bill before the United States House Homeland Security Subcommittee on Cybersecurity, Infrastructure Protection, and Security Technologies. On June 23, 2014, it was reported (amended) alongside House Report 113-491 part 1. On July 8, 2014, the House voted in a voice vote to pass the bill.
Debate and discussion
Rep. Meehan, who introduced the bill, argued that "the fertilizer plant explosion in West, Texas less than a year ago tragically demonstrated the potential for catastrophe at one of our country's thousands of chemical facilities. The Chemical Facility Anti-Terrorism Standards program is an important part of ensuring these facilities take reasonable precautions to protect against terrorist attack."
The Department of Homeland Security (DHS) supported the bill, arguing that "CFATS is making the Nation more secure by reducing the risks associated with our Nation’s chemical infrastructure." The DHS also argued that the reauthorization was necessary because "uncertainty about the future of CFATS also has provided an incentive for potentially regulated facilities storing large quantities of dangerous chemicals to ignore their obligations under CFATS in hopes that the program will be allowed to sunset."
The Fertilizer Institute supported the bill, arguing that it would allow the DHS to "effectively establish programs and make necessary changes to existing ones without worrying about whether or not the resources to administer them will be available in the future. The legislation would allow industry to be able to plan for investments with the certainty of knowing the program will be in place."
The National Association of Chemical Distributors supported the bill, arguing that it was important to reauthorize the program for two years to avoid situations like the one resulting from the United States federal government shutdown of 2013, when the law lapsed.
See also
List of bills in the 113th United States Congress
chemical plant
References
External links
Library of Congress - Thomas H.R. 4007
beta.congress.gov H.R. 4007
GovTrack.us H.R. 4007
OpenCongress.org H.R. 4007
WashingtonWatch.com H.R. 4007
Congressional Budget Office's report on H.R. 4007
House Report 113-491 part 1 on H.R. 4007
Acts of the 113th United States Congress
Chemical safety | Protecting and Securing Chemicals Facilities from Terrorist Attacks Act of 2014 | Chemistry | 1,611 |
52,442,739 | https://en.wikipedia.org/wiki/Pseudoenzyme | Pseudoenzymes are variants of enzymes that are catalytically-deficient (usually inactive), meaning that they perform little or no enzyme catalysis. They are believed to be represented in all major enzyme families in the kingdoms of life, where they have important signaling and metabolic functions, many of which are only now coming to light. Pseudoenzymes are becoming increasingly important to analyse, especially as the bioinformatic analysis of genomes reveals their ubiquity. Their important regulatory and sometimes disease-associated functions in metabolic and signalling pathways are also shedding new light on the non-catalytic functions of active enzymes, of moonlighting proteins, the re-purposing of proteins in distinct cellular roles (Protein moonlighting). They are also suggesting new ways to target and interpret cellular signalling mechanisms using small molecules and drugs. The most intensively analyzed, and certainly the best understood pseudoenzymes in terms of cellular signalling functions are probably the pseudokinases, the pseudoproteases and the pseudophosphatases. Recently, the pseudo-deubiquitylases have also begun to gain prominence.
Structures and roles
The difference between enzymatically active and inactive homologues has been noted (and in some cases, understood when comparing catalytically active and inactive proteins residing in recognisable families) for some time at the sequence level, owing to the absence of key catalytic residues. Some pseudoenzymes have also been referred to as 'prozymes' when they were analysed in protozoan parasites. The best studied pseudoenzymes reside amongst various key signalling superfamilies of enzymes, such as the proteases, the protein kinases, protein phosphatases and ubiquitin modifying enzymes. The role of pseudoenzymes as "pseudo scaffolds" has also been recognised and pseudoenzymes are now beginning to be more thoroughly studied in terms of their biology and function, in large part because they are also interesting potential targets (or anti-targets) for drug design in the context of intracellular cellular signalling complexes.
Examples classes
See also
Kinase
Pseudokinase
Phosphatome
Protein phosphatase
References
External links
Biochemistry
Cell signaling
Cancer | Pseudoenzyme | Chemistry,Biology | 459 |
18,605,515 | https://en.wikipedia.org/wiki/Bricard%20octahedron | In geometry, a Bricard octahedron is a member of a family of flexible polyhedra constructed by Raoul Bricard in 1897. The overall shape of one of these polyhedron may change in a continuous motion, without any changes to the lengths of its edges nor to the shapes of its faces.
These octahedra were the first flexible polyhedra to be discovered.
The Bricard octahedra have six vertices, twelve edges, and eight triangular faces, connected in the same way as a regular octahedron. Unlike the regular octahedron, the Bricard octahedra are all non-convex self-crossing polyhedra. By Cauchy's rigidity theorem, a flexible polyhedron must be non-convex, but there exist other flexible polyhedra without self-crossings. Avoiding self-crossings requires more vertices (at least nine) than the six vertices of the Bricard octahedra.
In his publication describing these octahedra, Bricard completely classified the flexible octahedra. His work in this area was later the subject of lectures by Henri Lebesgue at the Collège de France.
Construction
A Bricard octahedron may be formed from three pairs of points, each symmetric around a common axis of 180° rotational symmetry, with no plane containing all six points. These points form the vertices of the octahedron. The triangular faces of the octahedron have one point from each of the three symmetric pairs. For each pair, there are two ways of choosing one point from the pair, so there are eight triangular faces altogether. The edges of the octahedron are the sides of these triangles, and include one point from each of two symmetric pairs. There are 12 edges, which form the octahedral graph .
As an example, the six points (0,0,±1), (0,±1,0), and (±1,0,0) form the vertices of a regular octahedron, with each point opposite in the octahedron to its negation, but this is not flexible. Instead, these same six points can be paired up differently to form a Bricard octahedron, with a diagonal axis of symmetry. If this axis is chosen as the line through the origin and the point (0,1,1), then the three symmetric pairs of points for this axis are
(0,0,1)—(0,1,0), (0,0,−1)—(0,−1,0), and (1,0,0)–(−1,0,0). The resulting Bricard octahedron resembles one of the extreme configurations of the second animation, which has an equatorial antiparallelogram.
As a linkage
It is also possible to think of the Bricard octahedron as a mechanical linkage consisting of the twelve edges, connected by flexible joints at the vertices, without the faces. Omitting the faces eliminates the self-crossings for many (but not all) positions of these octahedra. The resulting kinematic chain has one degree of freedom of motion, the same as the polyhedron from which it is derived.
Explanation
The quadrilaterals formed by the edges between the points in any two symmetric pairs of points can be thought of as equators of the octahedron. These equators have the property (by their symmetry) that opposite pairs of quadrilateral sides have equal length. Every quadrilateral with opposite pairs of equal sides, embedded in Euclidean space, has axial symmetry, and some (such as the rectangle) have other symmetries besides. If one cuts the Bricard octahedron into two open-bottomed pyramids by slicing it along one of its equators, both of these open pyramids can flex, and the flexing motion can be made to preserve the axis of symmetry of the whole shape. But, by the symmetries of its construction, the flexing motions of these two open pyramids both move the equator along which they were cut in the same way. Therefore, they can be glued back together into a single flexing motion of the whole octahedron.
The property of having opposite sides of equal length is true of the rectangle, parallelogram, and antiparallelogram, and it is possible to construct Bricard octahedra having any of those flat shapes as their equators.
However, the equator of a Bricard octahedron is not required to lie in a plane; instead, it can be a skew quadrilateral. Even for Bricard octahedra constructed to have a flat equator, the equator generally does not remain flat as the octahedron flexes. However, for some Bricard octahedra, such as the octahedron with an antiparallelogram equator shown in the illustration, the symmetries of the polyhedron cause its equator to remain planar at all times.
Additional properties
The Dehn invariant of any Bricard octahedron remains constant as it undergoes its flexing motion. This same property has been proven for all non-self-crossing flexible polyhedra. However, there exist other self-crossing flexible polyhedra for which the Dehn invariant changes continuously as they flex.
Extensions
It is possible to modify the Bricard polyhedra by adding more faces, in order to move the self-crossing parts of the polyhedron away from each other while still allowing it to flex. The simplest of these modifications is Steffen's polyhedron, discovered by Klaus Steffen, with nine vertices and 14 triangular faces. However, although it has been claimed to be the simplest possible flexible polyhedron without self-crossings, a 2024 preprint by Gallet et al. claims to construct a simpler non-self-crossing flexible polyhedron with only eight vertices. Their polyhedron is obtained by combining two Bricard octahedra to form a self-crossing flexible pentagonal bipyramid, and then replacing one of its faces by three triangles to eliminate the self-crossing.
By connecting together multiple shapes derived from the Bricard octahedron, it is possible to construct horn-shaped rigid origami forms whose shape traces out complicated space curves.
References
Nonconvex polyhedra
Mathematics of rigidity
Linkages (mechanical) | Bricard octahedron | Physics | 1,345 |
28,752,828 | https://en.wikipedia.org/wiki/Seabrook%20Floodgate | The Inner Harbor Navigation Canal (IHNC) Seabrook Floodgate Structure is a flood barrier in the Industrial Canal in New Orleans, Louisiana. The floodgate is designed to protect the Industrial Canal and the surrounding areas from a storm surge from Lake Pontchartrain. It consists of two wide vertical lift gates and a wide sector gate.
The building of the floodgate was authorized by Congress in 2006 and operated in tandem with the Lake Borgne Surge Reduction Barrier to reduce the risk of storm surge damage to some of the New Orleans region's most vulnerable areas – New Orleans East, metro New Orleans, the Ninth Ward, Gentilly, and St. Bernard Parish.
Design
The Seabrook Floodgate Structure consists of a sector gate and two vertical lift gates approximately south of the Senator Ted Hickey Bridge with flood wall tie-ins on the east and west sides. Other components of the Seabrook Floodgate project include added T-walls and the replacement of the existing Alabama Great Southern Railroad gate with a new taller gate that met the 100 year level of risk reduction; new T-walls that tie into a new vehicle gate built at the boat launch on Leon C. Simon Drive; and raising the Hayne Boulevard ramps on both the east and west sides of the canal. The Seabrook structure closed the only remaining gap on the East Bank of the Hurricane and Storm Damage Risk Reduction System.
Construction
The US Army Corps of Engineers awarded the construction of the project to Alberici Constructors, Inc. in July 2009 Construction started in the fall of 2010, and although construction activities continued beyond the Corps' projected June 1, 2011 deadline, a temporary cofferdam was built to reduce risk to the area during the construction.
The floodgate structure opened to marine traffic in August 2012. The same month it was closed for the first time, in order to protect the city from Hurricane Isaac.
Notable flooding was not seen in the protected area from Category 4 Hurricane Ida in 2021. Water levels on Lake Pontchartrain were slightly lower than Hurricane Katrina, but significant -- areas further west of the city, such as LaPlace, were inundated by high waters. Work to increase protection for the areas further west of New Orleans has come to fruition in the West Shore Lake Pontchartrain project, for which construction began in December 2022.
Notes
Flood barriers
Buildings and structures in New Orleans
United States Army Corps of Engineers
Flood control in the New Orleans metropolitan area
Lake Pontchartrain | Seabrook Floodgate | Engineering | 500 |
33,666,376 | https://en.wikipedia.org/wiki/Huawei%20SingleRAN | Huawei SingleRAN is a radio access network (RAN) technology offered by Huawei that allows mobile telecommunications operators to support multiple mobile communications standards and wireless telephone services on a single network. The technology incorporates a software-defined radio device, and is designed with a consolidated set of hardware components, allowing operators to purchase, operate and maintain a single telecommunications network and set of equipment, while supporting multiple mobile communications standards.
History
Huawei began to develop its SingleRAN technology in order to address network operators' demand for improved cost efficiency in managing telecommunications network sites, spectrum, pipeline and staff. In 2008, the company introduced the industry's first commercial SingleRAN product, which allowed mobile operators to switch from GSM to UMTS network standards or use both simultaneously. That year Huawei also launched a commercial network based on SingleRAN that offered simultaneous CDMA and LTE modes.
Deployment
In May 2009, América Móvil, the largest mobile operator in Latin America, deployed Huawei's SingleRAN GSM and UMTS system in Panama, providing its customers with voice and data services from GSM and UMTS networks simultaneously. According to The Economist, América Móvil found that the power consumption of its base stations was reduced by 50% and the volume of equipment it needed was reduced by 70%, following deployment of Huawei's SingleRAN hardware.
In June 2009, Huawei's SingleRAN technology was selected by TeliaSonera for Europe's first GSM/UMTS network with software-defined radio (SDR) technology. TeliaSonera used Huawei SingleRAN to provide its subscribers in Finland with both GSM and UMTS services using the same 900MHz spectrum. Later that year, in December 2009, TeliaSonera also used Huawei's SingleRAN LTE technology to launch the world's first LTE commercial network in Norway. That same month, Net4Mobility selected Huawei SingleRAN GSM system to deploy their GSM/LTE 900 MHz SDR network in Sweden.
Developments
In March 2010, Huawei achieved what it stated is a world-record 1.2 Gbit/s download speed on a demo network built around Huawei's prototype SingleRAN LTE-Advanced device. In November that year, the company released a new SingleRAN technology, enabling operators to migrate between WiMAX and LTE TDD networks. That same month, Aero2 selected Huawei's SingleRAN technology to deploy the world's first GSM and LTE 1800MHz SDR network in Poland, which was due to become operational in early 2011.
In the first half of 2011, Huawei launched a SingleRAN system that supported both WiMAX and LTE. To date, Huawei has deployed over 130 SingleRAN networks worldwide for global network operators including Telefónica, O2 Germany, China Unicom, America Movil, Telenor, Net4Mobility and TeliaSonera.
Products
Huawei has developed and provides four SingleRAN products for mobile network operators. According to Huawei, SingleRAN GSM is designed for mobile operators using GSM networks, allowing them to simultaneously offer GSM with UMTS or LTE. The product also aims to prepare operators for future evolution of technology, including moving to mobile broadband networks. Huawei's SingleRAN LTE allows mobile service operators to migrate to LTE networks, and also continue to offer GSM, EDGE, UMTS or HSPA. The technology provides download speeds of up to 100 Mbit/s. The SingleRAN@Broad system was launched by Huawei at the Mobile World Congress in Barcelona in February 2010. This product helps operators to accommodate large increases in mobile broadband traffic and reduce the per-bit costs of network operation. According to Huawei, SingleRAN@Broad is capable of increasing operators’ mobile broadband capacity to handle high traffic generated by smartphones and similar devices. In November 2010, Huawei released SingleRAN WiMAX/LTE TDD, which allows operators to migrate from WiMAX to LTE TDD networks by configuring the technology as either a WiMAX module, a LTE TDD module, or a dual-mode module.
In addition to the SingleRAN products for mobile telecommunications operators, Huawei also offers a SingleRAN product aimed at railway transport systems. SingleRAN GSM-R is a suite of communications technologies that are designed to improve telecommunications performance through long tunnels, over very long distances, and in high-traffic areas. Huawei began researching GSM-R technologies in 2001 and, according to Cellular News, is "one of only a few" GSM-R network providers in the world.
Awards
In September 2009, Huawei's SingleRAN Dual-Mode Remote Radio Unit 3808 won an InfoVision award in the category of “New Product Concepts” from the International Engineering Consortium (IEC) at the Broadband World Forum in Paris. The following year, at the Broadband World Forum in October 2010, Huawei's SingleRAN@Broad technology was awarded the 2010 InfoVision Award in the category of “Broadband Access Network Technologies and Services”. In May 2011, Huawei's SingleRAN 5-Band 3-Mode 1-Cabinet technology (BTS 3900L) won the “Best LTE Network Elements” award at the LTE World Summit. In June 2011, Huawei won a 2011 CDMA Development Group (CDG) Industry Achievement Award for its SingleRAN CDMA/LTE technology in the category of “Innovation in Network Technology and Mobile Applications.”
References
Radio technology
Huawei products | Huawei SingleRAN | Technology,Engineering | 1,138 |
13,574,246 | https://en.wikipedia.org/wiki/Monoethanolamine%20oleate | Monoethanolamine oleate (ethanolammonium oleate) is an organic compound with the formula [CH3(CH2)7CH=CH(CH2)7CO2][H3NCH2CH2OH].. A colorless oily liquid, it is an example of a protic ionic liquid. It is a salt formed by the reaction between monoethanolamine and oleic acid.
Antivaricose agent
As an antivaricose agent, it is injected topically into varicosities to cause sclerosis (closure) of the abnormal vein. It is indicated for the treatment of patients with esophageal varices that have recently bled, to prevent rebleeding. Ethanolamine is not indicated for the treatment of patients with esophageal varices that have not bled. There is no evidence that treatment of this population decreases the likelihood of bleeding. Sclerotherapy with ethanolamine has no beneficial effect upon portal hypertension, the cause of esophageal varices, so that recanalization and collateralization may occur, necessitating reinjection.
References
Ammonium compounds
Carboxylate anions | Monoethanolamine oleate | Chemistry | 246 |
20,058,756 | https://en.wikipedia.org/wiki/Hard%20hexagon%20model | In statistical mechanics, the hard hexagon model is a 2-dimensional lattice model of a gas, where particles are allowed to be on the vertices of a triangular lattice but no two particles may be adjacent.
The model was solved by , who found that it was related to the Rogers–Ramanujan identities.
The partition function of the hard hexagon model
The hard hexagon model occurs within the framework of the grand canonical ensemble, where the total number of particles (the "hexagons") is allowed to vary naturally, and is fixed by a chemical potential. In the hard hexagon model, all valid states have zero energy, and so the only important thermodynamic control variable is the ratio of chemical potential to temperature μ/(kT). The exponential of this ratio, z = exp(μ/(kT)) is called the activity and larger values correspond roughly to denser configurations.
For a triangular lattice with N sites, the grand partition function is
where g(n, N) is the number of ways of placing n particles on distinct lattice sites such that no 2 are adjacent. The function κ is defined by
so that log(κ) is the free energy per unit site. Solving the hard hexagon model means (roughly) finding an exact expression for κ as a function of z.
The mean density ρ is given for small z by
The vertices of the lattice fall into 3 classes numbered 1, 2, and 3, given by the 3 different ways to fill space with hard hexagons. There are 3 local densities ρ1, ρ2, ρ3, corresponding to the 3 classes of sites. When the activity is large the system approximates one of these 3 packings, so the local densities differ, but when the activity is below a critical point the three local densities are the same. The critical point separating the low-activity homogeneous phase from the high-activity ordered phase is with golden ratio φ. Above the critical point the local densities differ and in the phase where most hexagons are on sites of type 1 can be expanded as
Solution
The solution is given for small values of z < zc by
where
For large z > zc the solution (in the phase where most occupied sites have type 1) is given by
The functions G and H turn up in the Rogers–Ramanujan identities, and the function Q is the Euler function, which is closely related to the Dedekind eta function. If x = e2πiτ, then x−1/60G(x), x11/60H(x), x−1/24P(x), z, κ, ρ, ρ1, ρ2, and ρ3 are modular functions of τ, while x1/24Q(x) is a modular form of weight 1/2. Since any two modular functions are related by an algebraic relation, this implies that the functions κ, z, R, ρ are all algebraic functions of each other (of quite high degree) . In particular, the value of κ(1), which Eric Weisstein dubbed the hard hexagon entropy constant , is an algebraic number of degree 24 equal to 1.395485972... ().
Related models
The hard hexagon model can be defined similarly on the square and honeycomb lattices. No exact solution is known for either of these models, but the critical point zc is near for the square lattice and for the honeycomb lattice; κ(1) is approximately 1.503048082... () for the square lattice and 1.546440708... for the honeycomb lattice .
References
Exton, H. (1983), q-Hypergeometric Functions and Applications, New York: Halstead Press, Chichester: Ellis Horwood
External links
Exactly solvable models
Statistical mechanics
Lattice models
Modular forms
Algebraic numbers | Hard hexagon model | Physics,Materials_science,Mathematics | 809 |
24,551,923 | https://en.wikipedia.org/wiki/Phillips%20relationship | In astrophysics, the Phillips relationship is the relationship between the peak luminosity of a Type Ia supernova and the speed of luminosity evolution after maximum light. The relationship was independently discovered by the American statistician and astronomer Bert Woodard Rust and the Soviet astronomer in the 1970s. They found that the faster the supernova faded from maximum light, the fainter its peak magnitude was. As a main parameter characterizing the light curve shape, Pskovskii used β, the mean rate of decline in photographic brightness from maximum light to the point at which the luminosity decline rate changes. β is
measured in magnitudes per 100-day intervals. Selection of this parameter is justified by the fact that, at that time, the probability of discovering a supernova before the maximum light, and obtain the full light curve, was small. Moreover, the existing light curves were mostly incomplete. On the other hand, to determine the decline after the maximum light was rather simple for most observed supernovae.
In the early 1980s CCD cameras appeared, and the number of SNe discoveries increased substantially. Moreover, the probability of discovering SNe before they reached maximum light and following their brightness evolution longer also increased. The first light curves of SNe Ia obtained using CCD photometry showed that some supernovae had faster decline rates than others. Later, the low luminosity Ia SN 1991bg with a fast decline rate was discovered.
All this motivated the American astronomer Mark M. Phillips to revise this relationship precisely during the course of the Calán/Tololo Supernova Survey. The correlation had been difficult to prove because Pskovskii's slope (β) parameter was difficult to measure with precision in practice, a necessary condition to prove the correlation. Rather than trying to determine the slope, Phillips used a simpler and more robust procedure that consisted in "measuring the total amount in magnitudes that the light curve decays from its peak brightness during some specified period following maximum light." It was defined as the decline in the B-magnitude light curve from maximum light to the magnitude 15 days after B-maximum, a parameter he called . The lead sentence of the acknowledgments section of Phillips' paper states: "I am indebted to George Jacoby for suggesting the parameter as an alternative to Pskovskii's β." The relation states that the maximum intrinsic B-band magnitude is given by
Phillips dedicated the journal article confirming Yuri Pskovskii's proposed correlation to Pskovskii, who died a few weeks after Phillips' evidence confirming the relationship was published.
It has been recast to include the evolution in multiple photometric bandpasses, with a significantly shallower slope and as a stretch in the time axis relative to a standard template.
The relation is typically used to bring any Type Ia supernova peak magnitude to a standard candle value.
References
Astrophysics
Supernovae | Phillips relationship | Physics,Chemistry,Astronomy | 597 |
66,144,538 | https://en.wikipedia.org/wiki/Games%2C%20Puzzles%2C%20and%20Computation | Games, Puzzles, and Computation is a book on game complexity, written by Robert Hearn and Erik Demaine, and published in 2009 by A K Peters. It is revised from Hearn's doctoral dissertation, which was supervised by Demaine. The Basic Library List Committee of the Mathematical Association of America has recommended it for inclusion in undergraduate mathematics libraries.
Topics
Games, Puzzles, and Computation concerns the computational complexity theory of solving logic puzzles and making optimal decisions in two-player and multi-player combinatorial games. Its focus is on games and puzzles that have seen real-world play, rather than ones that have been invented for a purely mathematical purpose. In this area it is common for puzzles and games such as sudoku, Rush Hour, reversi, and chess (in generalized forms with arbitrarily large boards) to be computationally difficult: sudoku is NP-complete, Rush Hour and reversi are PSPACE-complete, and chess is EXPTIME-complete. Beyond proving new results along these lines, the book aims to provide a unifying framework for proving such results, through the use of nondeterministic constraint logic, an abstract combinatorial problem that more closely resembles game play than the more classical problems previously used for completeness proofs.
It is divided into three parts. The first part concerns constraint logic, which involving assigning orientations to the edges of an undirected graph so that each vertex has incoming edges with large-enough total weight. The second part of this book applies constraint logic in new proofs of hardness of various real-world games and puzzles, by showing that, in each case, the vertices and edges of a constraint logic instance can be encoded by the moves and pieces of the game. Some of these hardness proofs simplify previously-known proofs; some ten of them are new, including the discovery that optimal play in certain multiplayer games can be an undecidable problem. A third part of the book provides a compendium of known hardness results in game complexity, updating a much shorter list of complete problems in game complexity from the 1979 book Computers and Intractability. An appendix provides a review of the methods from computational complexity theory needed in this study, for readers unfamiliar with this area.
Audience and reception
Although primarily a research monograph and reference work for researchers in this area, reviewer Oswin Aichholzer recommends the book more generally to anyone interested in the mathematics of games and their complexity. Liljana Babinkostova writes that Games, Puzzles, and Computation is enjoyable reading, successful in its "purpose of building a bridge between games and the theory of computation".
Leon Harkleroad is somewhat more critical, writing that the book feels padded in places, and Joseph O'Rourke complains that its organization, with many pages of abstract mathematics before reaching the real-world games, does not lend itself to cover-to-cover reading. However, both Harkleroad and O'Rourke agree that the book is well-produced and thought-provoking.
References
Mathematics books
2009 non-fiction books
Combinatorial game theory
Computational complexity theory | Games, Puzzles, and Computation | Mathematics | 641 |
48,462,486 | https://en.wikipedia.org/wiki/Claudine%20Rinner | Claudine Rinner (born 1965) is a French amateur astronomer from Ottmarsheim in Alsace, France. She is an observer at Ottmarsheim Observatory and a discoverer of minor planets and comets, who received the Edgar Wilson Award for her discoveries.
Career
Participant in the Morocco Oukaimeden Sky Survey (MOSS), Rinner discovered three comets using a 0.5-metre robotic telescope at Oukaïmeden Observatory located in Morocco. She won the 2013 Edgar Wilson Award for discovering three comets which were designated 373P/Rinner (P/2011 W2), (MOSS), and 281P/MOSS (). Rinner is also credited by the Minor Planet Center with the discovery of more than 100 minor planets since 2004, including several co-discoveries with François Kugel (see list below).
Awards and honors
The asteroid 23999 Rinner, discovered by French amateur astronomer Laurent Bernasconi in 1999, was named in her honor. The official was published by the Minor Planet Center on 21 July 2005 ().
In 2020, she and Michel Ory jointly received the Dorothea Klumpke – Isaac Roberts prize from the Société astronomique de France.
Discoveries
List of discovered minor planets
Some of Claudine Rinner's discoveries were made in collaboration with François Kugel
See also
References
External links
En bref : cocorico, enfin une comète française !
Le projet MOSS (2011-2018), Michel Ory
21st-century French astronomers
Amateur astronomers
01
1965 births
Living people
Discoverers of asteroids
French women astronomers
20th-century French astronomers
20th-century French women scientists
21st-century French women scientists
Women planetary scientists
Planetary scientists | Claudine Rinner | Astronomy | 351 |
56,953,827 | https://en.wikipedia.org/wiki/Andrew%20Hessel | Andrew Hessel is a pioneer in synthetic biology, a futurist, microbiologist and geneticist, and inventor and entrepreneur. He is a proponent of open source biology and advocates that cells are living computers and DNA is a programming language. He has been advocating for writing DNA since shortly after the original Human Genome Project, and co-founded the Genome Project-write. Hessel is an expert in biological technologies and biosecurity, helping industry, academics, and authorities better understand the rapid changes in life science.
Life and Education
Andrew Hessel was born in Canada and currently resides in the United States. He received a M.Sc. in biology from University of Calgary in 1995.
Career and Entrepreneurship
Andrew Hessel is a serial entrepreneur. In 2002, he co-founded Miikana Therapeutics, a clinical-stage drug development company. In 2009 he founded Pink Army Cooperative, the world’s first cooperative biotechnology company, which aimed to make open source viral therapies for cancer. Hessel is founding faculty and former co-chair of Bioinformatics and Biotechnology at Singularity University where he worked to develop the Life Sciences track. From 2012 to 2018, Hessel was a Distinguished Researcher in the Bio/Nano Programmable Matter department at Autodesk. Hessel then co-founded the Genome Project-write in 2016 where he is currently Chairman of the Board and Co-Executive Director. In 2017, Hessel co-founded Humane Genomics, Inc., which uses synthetic virus engineering to target cancer cells.
He previously worked at the Amgen Institute and he was a fellow at the Institute for Science, Society, and Policy at the University of Ottawa.
Genome Project-write (GPW)
Hessel is a long time proponent of writing DNA and was the catalyst behind the Genome Project-write (GPW). In 2012, he published an article about the next Human Genome Project. It gained little traction. Three years later in 2015 at the fourth Sc2.0 Conference, a meeting of scientists working on the yeast genome led by Jef Boeke, Nancy J. Kelley posed the question, “Well, what’s the next grand challenge for this community?” Hessel replied “Well, there’s only one grand challenge in synthetic biology to my mind, and that is to synthesize a human genome." Hessel then approached geneticist George Church at Harvard and asked him to lead the project. Together, Hessel, Church, Kelley and Boeke co-founded the Genome Project-write in 2016. Autodesk provided the seed funding to launch the Genome Project-write.
The project launched to controversy over its perceived secrecy. The founders were forbidden to discuss the project openly with the press due to an embargo by Science magazine, which had delayed its publication of their foundational papers until after the scheduled meeting. The project also encountered mixed response within the synthetic biology and scientific community.
Work
Hessel was an early supporter of, ambassador to, and judge at the international Genetically Engineered Machines iGEM competitions at MIT, helping it grow in its early stages.
While at Autodesk, Hessel, along with Paul Jaschke and Jacqueline Quinn, designed and synthesized φX174 in under three weeks and for approximately $1000USD using digital tools. It exemplified the rapid advancement of tools in synthetic biology. Paola Antonelli, the director of R&D at the Museum of Modern Art in NYC acquired the symbolic 3D printed plastic virus of φX174 as the first engineered organism in MoMA’s collection.
In 2015, Hessel became a AAAS-Lemelson Invention Ambassador after being nominated by his friend and renowned mycologist, Paul Stamets, who had been in the inaugural class of Invention Ambassadors. The program inspired Hessel to approach George Church to co-found the Genome Project-write.
In February 2022, Hessel's book, The Genesis Machine: Our Quest to Rewrite Life in the Age of Synthetic Biology with futurist Amy Webb was published by PublicAffairs/Hachette Book Group. It was a New Yorker Best Book of 2022.
Hessel regularly speaks to private and public audiences on biotechnology and biodefense topics for groups such as EY, CERN, Stanford, the FBI, the United Nations, ISHI, Singularity University, Forbes, and TEDx. He has been listed as a participant or member of think tanks and organizations such as the Berggruen Institute, Geneva Science and Diplomacy Anticipator (GESDA), and the Long Now Foundation.
Ideas
Hessel has publicly shared other futurist ideas about life underground, human cloning and biobanking.
References
External links
Autodesk Life Sciences
Pink Army Cooperative
Year of birth missing (living people)
Living people
American geneticists
American technology chief executives
American technology company founders
Biotechnologists
Synthetic biologists | Andrew Hessel | Biology | 997 |
1,564,675 | https://en.wikipedia.org/wiki/HD%2063454 | HD 63454, formally named Ceibo, is a star located in the southern circumpolar constellation Chamaeleon near the border with Mensa. To see the star, one needs a small telescope because it has an apparent magnitude of 9.36, which is below the limit for naked eye visibility. The object is located relatively close at a distance of 123 light years based on Gaia DR3 parallax measurements but is receding with a heliocentric radial velocity of . At its current distance, HD 63454's brightness is diminished by two tenths of a magnitude due to interstellar dust. It has an absolute magnitude of +6.68.
Properties
HD 63454 has a stellar classification of K3 V(k), indicating that it is a K-type main-sequence star with some infilling of the calcium K and H lines. It has 79% the mass of the Sun and 80% the Sun's radius. It radiates 28.7% the luminosity of the Sun from its photosphere at an effective temperature of , giving it an orange hue. HD 63454 has a solar metallicity and is estimated to 1.52 billion years old, a third the age of the Sun. It spins modestly with a projected rotational velocity of .
Planetary system
On Valentine’s Day 2005, a hot Jupiter HD 63454 b was found by Claire Moutou, Michel Mayor, and François Bouchy using the radial velocity method.
After the 2019 IAU100 NameExoWorlds campaign, the International Astronomical Union, approved the names proposed from Uruguay: Ceibo for the star and Ibirapitá for the planet, respectively after the native Uruguayan tree species Erythrina crista-galli and Peltophorum dubium.
These names were announced on 17 December 2019, at a press conference of the IAU in Paris, together with other 111 sets of exoplanets and host stars. Ceibo and Ibirapitá were proposed by Adrián Basedas, from the Astronomical Observatory of Liceo Nº9, Montevideo, Uruguay, who won the national contest "Nombra Tu Exoplaneta", organized in Uruguay, to name HD 63454 and HD 63454 b.
See also
List of extrasolar planets
References
External links
K-type main-sequence stars
063454
037284
Chamaeleon
Planetary systems with one confirmed planet
CD-77 00298 | HD 63454 | Astronomy | 514 |
48,350,186 | https://en.wikipedia.org/wiki/Radulomyces%20confluens | Radulomyces confluens is a species of crust fungus in the family Pterulaceae. It was originally described in 1815 by Elias Magnus Fries with the name Thelephora confluens. Danish botanist Mads Peter Christiansen made it the type species of his newly-circumscribed genus Radulomyces in 1960.
References
External links
Fungi described in 1815
Pterulaceae
Taxa named by Elias Magnus Fries
Fungus species | Radulomyces confluens | Biology | 97 |
4,454,120 | https://en.wikipedia.org/wiki/Chromomycin%20A3 | Chromomycin A3 (CMA3) or Toyomycin is an anthraquinone antibiotic glycoside produced by the fermentation of a certain strain of Streptomyces griseus (No. 7).
Fluorescence properties
In the presence of Mg2+ ions, Chromomycin A3 binds reversibly to DNA, preferentially to contiguous G/C base pairs.
When bound to DNA, Chromomycin A3 has a maximum excitation wavelength of 445 nm (blue), and a maximum emission wavelength of 575 nm (yellow).
Uses
in-vitro membrane-impermeant G/C-specific fluorescent DNA-binding dye.
in-vitro antibiotic of gram-positive bacteria, through inhibition of the incorporation of Pi in the RNA.
in-vitro anticancer drug that inhibits RNA synthesis.
Evaluation of male fertility: Chromomycin A3 and protamines compete for the same binding sites in the DNA, so CMA3 positivity in spermatozoa reflects protamine deficiency (affecting sperm morphology and decreasing fertility).
References
Antibiotics
Anthraquinone glycosides | Chromomycin A3 | Biology | 246 |
75,401,320 | https://en.wikipedia.org/wiki/Anna%20Giacomini | Anna Giacomini is an Italian civil engineer, a fellow of the Australian Academy of Technological Sciences and Engineering in 2023, and a professor at the University of Newcastle.
Education
Giacomini has 20 years of experience in Rock Mechanics and Civil Engineering. She was awarded a PhD from the University of Parma, Italy, in 2003. In 2007 she joined the University of Newcastle as a research academic. Giacomini with a research background in rockfall analysis and rock mechanics, applied to mining within the Australian landscape. She was the principal researcher of an Australian Research Council Linkage Project from 2009 to 2011, Giacomini played a role in developing barrier designs aimed at safeguarding infrastructure such as roads and railways from rockfall hazards.
Career
Giacomini is a professor at the University of Newcastle, in NSW, Australia. Gioacomini works in the field of rock mechanics and rockfall analyses. She has served as editorial board member of four International Journals in the field of civil engineering, as reviewer for several national and international funding bodies in the rock mechanics and engineering fields. She is also a member of the ARC College of Experts. Her work was described, after winning the Booker prize from the Australian Academy of Science, in 2019, as:"...significantly improved safety within the Australian mining industry, where rockfalls threaten human lives, the portal structures for underground entry, and damage to machinery."Giacomini is one of the co-founders of the HunterWISE - Women in STEM program.
Publications
Giacomini has published over 150 scientific works, with an H index of 27 in 2023. The following are select publications:
GP Giani, A Giacomini, M Migliazza, A Segalini (2004) Experimental and theoretical studies to improve rock fall analysis and protection work design. Rock Mechanics and Rock Engineering 37, 369-389 https://doi.org/10.1016/j.ijrmms.2008.09.007
A Giacomini, O Buzzi, B Renard, GP Giani (2009) Experimental studies on fragmentation of rock falls on impact with rock surfaces. International Journal of Rock Mechanics and Mining Sciences: 46:(4)708-715. https://doi.org/10.1016/j.ijrmms.2008.09.007
K Thoeni, A Giacomini, C Lambert, S W Sloan, J P Carter (2014) A 3D discrete element modelling approach for rockfall analysis with drapery systems. International Journal of Rock Mechanics and Mining Sciences. 68:107-119. https://doi.org/10.1016/j.ijrmms.2014.02.008
Awards
2023 - Fellow of the Australian Academy of Technological Sciences and Engineering.
2022 - Prize for Excellence in Engineering or Information and Communications Technology, NSW Premier's Prizes for Science & Engineering.
2019 John Booker Medal from the Australian Academy of Science.
2019 Best Practice Industry Engagement Award, received from the Newcastle Institute for Energy and Resources.
2018 - Vice Chancellor's Award for Research Supervisor of the year.
References
External links
University of Newcastle Profile
Science Awards
ATSE Fellows
Living people
Civil engineers
Fellows of the Australian Academy of Technological Sciences and Engineering
21st-century Italian engineers
Year of birth missing (living people)
21st-century Italian women engineers | Anna Giacomini | Engineering | 681 |
23,433,345 | https://en.wikipedia.org/wiki/Coremark | CoreMark is a benchmark that measures the performance of central processing units (CPU) used in embedded systems. It was developed in 2009 by Shay Gal-On at EEMBC and is intended to become an industry standard, replacing the Dhrystone benchmark. The code is written in C and contains implementations of the following algorithms: list processing (find and sort), matrix manipulation (common matrix operations), state machine (determine if an input stream contains valid numbers), and CRC. The code is under the Apache License 2.0 and is free of cost to use, but ownership is retained by the Consortium and publication of modified versions under the CoreMark name prohibited.
Issues addressed by CoreMark
The CRC algorithm serves a dual function; it provides a workload commonly seen in embedded applications and ensures correct operation of the CoreMark benchmark, essentially providing a self-checking mechanism. Specifically, to verify correct operation, a 16-bit CRC is performed on the data contained in elements of the linked list.
To ensure compilers cannot pre-compute the results at compile time every operation in the benchmark derives a value that is not available at compile time. Furthermore, all code used within the timed portion of the benchmark is part of the benchmark itself (no library calls).
CoreMark versus Dhrystone
CoreMark draws on the strengths that made Dhrystone so resilient - it is small, portable, easy to understand, free, and displays a single number benchmark score. Unlike Dhrystone, CoreMark has specific run and reporting rules, and was designed to avoid the well understood issues that have been cited with Dhrystone.
Major portions of Dhrystone are susceptible to a compiler’s ability to optimize the work away; thus it is more a compiler benchmark than a hardware benchmark. This also makes it very difficult to compare results when different compilers/flags are used.
Library calls are made within the timed portion of Dhrystone. Typically, those library calls consume the majority of the time consumed by the benchmark. Since the library code is not part of the benchmark, it is difficult to compare results if different libraries are used.
Guidelines exist on how to run Dhrystone but since results are not certified or verified, they are not enforced. There is no standardization on how Dhrystone results should be reported, with various formats in use (DMIPS, Dhrystones per second, DMIPS/MHz)
Results
CoreMark results can be found on the CoreMark web site, and on processor data sheets. Results are in the following format:
CoreMark 1.0 : N / C / P / M
N Number of iterations per second (with seeds 0,0,0x66,size=2000)
C Compiler version and flags
P Parameters such as data and code allocation specifics
M – Type of Parallel algorithm execution (if used) and number of contexts
For example: CoreMark 1.0 : 128 / GCC 4.1.2 -O2 -fprofile-use / Heap in TCRAM / FORK:2
See also
Business Applications Performance Corporation (BAPCo)
Embedded Microprocessor Benchmark Consortium (EEMBC)
Standard Performance Evaluation Corporation (SPEC)
Transaction Processing Performance Council (TPC)
References
External links
EEMBC CoreMark Public Group
Embedded systems
Benchmarks (computing) | Coremark | Technology,Engineering | 693 |
67,687,783 | https://en.wikipedia.org/wiki/Topographic%20steering | In fluid mechanics, topographic steering is the effect of potential vorticity conservation on the motion of a fluid parcel. This means that the fluid parcels will not only react to physical obstacles in their path, but also to changes in topography or latitude. The two types of 'fluids' where topographic steering is mainly observed in daily life are air (air can be considered a compressible fluid in fluid mechanics) and water in respectively the atmosphere and the oceans. Examples of topographic steering can be found in, among other things, paths of low pressure systems and oceanic currents.
In 1869, Kelvin published his circulation theorem, which states that a barotropic, ideal fluid with conservative body forces conserves the circulation around a closed loop. To generalise this, Bjerknes published his own circulation theorem in 1898. Bjerknes extended the concept to inviscid, geostrophic and baroclinic fluids, resulting in addition of terms in the equation.
Mathematical description
Circulation
The exact mathematical description of the different potential vorticities can all be obtained from the circulation theorem of Bjerkness, which is stated as
.
Here is the circulation, the line integral of the velocity along a closed contour. Also, is the material derivative, is the density, is the pressure, is the angular velocity of the frame of reference and is the area projection of the closed contour onto the equatorial plane. This means the bigger the angle between the contour and the equatorial plane, the smaller this projection becomes.
The formula states that the change of the circulation along a fluid's path is affected by the variation of density in pressure coordinates and by the change in equatorial projection of the contour. Kelvin assumed both a barotropic fluid and a constant projection. Under these assumptions the right hand side of the equation is zero and Kelvin's theorem is found.
Shallow water
When considering a relatively thin layer of fluid of constant density, with on the bottom a topography and on top a free surface, the shallow water approximation can be used. Using this approximation, Rossby showed in 1939, by integrating the shallow water equations over the depth of the fluid, that
.(1)
Here is the relative vorticity, is the Coriolis parameter and is the height of the water layer. The quantity inside the material derivative was later called the shallow water potential vorticity.
Layered atmosphere
When considering an atmosphere with multiple layers of constant potential temperature, the quasi-2D shallow water equations on a beta plane can be used. In 1940, Rossby used this to show that
.(2)
Here is the relative vorticity on an isentropic surface, is the Coriolis parameter and is a quantity measuring the weight of unit cross-section of an individual air column in the layer. This last quantity can also be seen as a measure of the vortex depth. The potential vorticity defined here is also called the Rossby potential vorticity.
Continuous atmosphere
When the approximation of the discrete layers is relaxed and the fluid becomes continuous, another potential vorticity can be defined which is conserved. It was shown by Ertel in 1942 that
.(3)
Here is the absolute vorticity, is the gradient in potential temperature and the density. This potential vorticity is also called the Ertel potential vorticity.
To get to this result, first recall the circulation theorem from Kelvin
.
If the coordinate system is transformed to the one of the local tangent plane coordinates and we use potential temperature as the vertical coordinate, the equation can be slightly rewritten to
.
Where now is the local circulation in the frame of reference, is Coriolis parameter and is the area on an isentropic surface over which the circulation .
Because the local circulation can be approximated as a product between the area and the relative vorticity on the isentropic surface, the circulation equation yields
.
When a fluid parcel is between two isentropic layers and the pressure difference between these layers increases, the fluid parcel is 'stretched'. This is because it wants to conserve the potential temperature at each side of the parcel. To conserve the mass, this horizontally thins the fluid parcel while it is vertically stretched. So the area of the isentropic surface, , is a function of how quickly the lines of equal potential temperature change with pressure:
.
In the end this yields
,
which is exactly the result found by Ertel, written in a slightly different way. Note that when assuming a layered atmosphere, the gradient in the potential temperature becomes an absolute difference and the result from Kelvin for a layered atmosphere can be found. Also note that when the fluid is incompressible, the layer depth becomes a measure for the change in potential temperature. Then the result for shallow water potential vorticity can be extracted again.
Effect
The different definitions of potential vorticity conservation, resulting from different approximations, can be used to explain phenomena observed here on earth. Fluid parcels will move along lines of constant potential vorticity.
Oceans
Because the scale of large flows in the oceans is much larger than the depth of the ocean, the shallow water approximation and thus (1) can often be used. On top of that, the changes in relative vorticity are very small with respect to the changes in the Coriolis parameter. The direct result of that is that for a fluid parcel a change in ocean floor depth will have to be compensated by a change in latitude. In both hemispheres this means that a rising ocean floor, so a decrease in water depth, results in a deflection equatorwards.
This phenomenon can explain different currents found on earth. One of them is the specific path the water takes in the Antarctic Circumpolar Current. This path is not a straight line, but curves according to the bathymetry.
Another one is the water flowing through the Luzon Strait. Researchers Metzger and Hurlburt showed that the existence of three small shoals can explain the deflection of the current away from the strait instead of flowing through the strait.
Atmosphere
In the atmosphere, topographic steering can also be observed. In most cases, the simple modeled layer of the atmosphere and thus (2) can explain the phenomena. When an isentropic layer flows zonally from west to east over a mountain, the topographic steering can create a wave-like pattern on the lee-side and eventually form an alternating pattern of ridges and troughs.
Upon approach of the mountain, the layer depth will increase slightly. This is because the incline of the isentropic surfaces is less steep at the top of the layer than at the bottom. When the layer depth increases, the change in potential vorticity is countered by an increase in relative vorticity as well as the Coriolis parameter. The vortex will begin to move away from the equator and begin to rotate cyclonically.
During the crossing of the mountain, the effect is reversed due to the shrinking of the layer depth. The vortex will rotate anti-cyclonically and move towards the equator. As the vortex leaves the mountain, the resulting latitude is closer to the equator than before. This means vortices will have a cyclonic rotation on the lee-side of the mountain and be turning northwards. The Coriolis parameter and relative vorticity increase and decrease in antiphase. This results in an alternation of cyclonic and anti-cyclonic flows after the mountain. The change in the Coriolis parameter and relative vorticity work against each other, creating a wave-like phenomenon.
When looking at zonal flow from east to west, this effect is not occurring. This is because the change in the Coriolis parameter and the change in relative vorticity work in the same direction. The flow will return to zonal again some time after crossing the mountain.
The effect described is often credited as the source of the tendency of cyclogenesis on lee-sides of mountains. One example of this are the so called Colorado lows, troughs originating from air passing over the Rocky Mountains.
See also
Potential vorticity
Circulation (physics)
Kelvin's circulation theorem
Shallow water equations
References
Oceanography
Atmospheric dynamics
Fluid mechanics | Topographic steering | Physics,Chemistry,Engineering,Environmental_science | 1,672 |
51,449,972 | https://en.wikipedia.org/wiki/California%20drought%20manipulation%20conspiracy%20theory | The California drought manipulation conspiracy theory is a conspiracy theory that proposes that the 2011–2017 drought was a deliberate, man-made phenomenon, created by weather modification. It is largely promoted by a number of self-proclaimed "independent researchers" and "scientists", and by alternative news outlets. The theory has been dismissed by the scientific community and mainstream media as fringe science or pseudoscience.
Key claims and components
The 2011–2017 drought inspired alarm among many, leading to the emergence of conspiracy theories purporting to explain the cause of a complex problem using oversimplified and non-evidence-based explanations.
Many of the proponents claim that chemtrails are used to affect storm clouds, in such a manner as to suppress the development of precipitation. This would occur because of the presence of too many cloud condensation nuclei, or "cloud seeds", in a single area. Others say that technologies similar to HAARP (a federal ionospheric research program, which was decommissioned in 2015), are being used to create a large and stubborn high-pressure area over the West Coast of the United States. They claim that this, also, discourages storms and rainfall.
Dane Wigington and his group GeoEngineering Watch were the most visible proponents of this theory. Wigington said that government agencies and other entities have economic and geopolitical motivations to manipulate the weather on the West Coast and elsewhere.
Proponents have claimed credibility for the theory, in part, as a result of a Los Angeles County cloud seeding program, begun in early 2016. This reinforced their view that government continues to engage in weather modification and/or climate engineering.
See also
References
Conspiracy theories in the United States
Droughts in the United States
Earth science conspiracy theories
Environmental issues in California
Fringe science
Pseudoscience | California drought manipulation conspiracy theory | Technology | 366 |
70,798,598 | https://en.wikipedia.org/wiki/Aurantimycin%20A | Aurantimycin A is a depsipeptide antibiotic with the molecular formula C38H64N8O14. Aurantimycin A is produced by the bacterium Streptomyces aurantiacus. Aurantimycin A also show cytotoxic properties.
References
Further reading
Antibiotics
Depsipeptides
Cyclic peptides | Aurantimycin A | Chemistry,Biology | 75 |
17,798,384 | https://en.wikipedia.org/wiki/Operationally%20Responsive%20Space%20Office | The Operationally Responsive Space Office (ORS Office) is a joint initiative of the United States Department of Defense (DoD). The "stand up" of the office took place 21 May 2007 at Kirtland Air Force Base. The first director of the ORS Office was Col. Kevin McLaughlin, who was also the commander of the Space Development and Test Wing located at Kirtland. The ORS Office focuses on providing quick-response tactical space-based capabilities; utilizing smaller satellites, such as the Tactical Satellite Program and smaller launch vehicles.
Organizations that have been involved in ORS activities include the United States Space Force, United States Army, the United States Navy, DARPA, the National Reconnaissance Office, the Missile Defense Agency and NASA.
Leadership
Col. John Anttonen took over as Director of the ORS Office in February 2013.
Previous directors
Peter Wegner was director of ORS from May 2008.
History
The Joint ORS Office is working with the other space agencys to provide "(an) assured space power focused on timely satisfaction of Joint Force Commanders' needs". The end state of the ORS concept is the ability to address emerging, persistent, or unanticipated needs.
The ORS Office is implementing a process using a Modular Open Systems Architecture (MOSA) to facilitate rapid assembly, integration, and test (AI&T), deployment, and operations of space assets into the current space architecture in operationally relevant timelines. The ORS Office focuses on material and non-material solutions.
Mission
The Joint ORS Office is taking a new approach to risk and mission assurance to rapidly deploy capabilities to satisfy warfighter needs across operations.
Satellites
Jumpstart
On May 29, 2008 SpaceDev announced its Trailblazer spacecraft bus had been selected by the ORS Office as the primary payload to fly on its inaugural "Jumpstart" mission. The Jumpstart payload was carried by the third Falcon 1 flight, which launched from Kwajalein in August 2008 but failed to reach orbit.
ORS-1
June 29, 2011 ORS-1 was launched from the Mid-Atlantic Regional Spaceport on Wallops Island on a Minotaur I rocket.
TacSat-3
TacSat-3 is the first on-orbit Department of Defense intelligence, surveillance and reconnaissance capability delivered to U.S. Strategic Command for their direct imagery support to worldwide combatant commanders. TacSat-3 complements the wide array of Intelligence Community Combat Support Agencies and other space-based ISR systems that provide information to the United States armed forces.
TacSat-4
TacSat-4 was launched on September 27, 2011. The Operationally Responsive Space (ORS) Office and Air Force's Space and Missile Systems Center (SMC) provided the launch on a Minotaur IV from Kodiak, Alaska.
ORS-4
Launch on November 4, 2015 GMT (November 3, Hawaii Standard Time) of a SPARK, also called Super Strypi, rocket occurred using a new rail-guided system; this was the first launch from Hawaii. Spaceflight Now received a statement from the Air Force that "The ORS-4 mission on an experimental Super Strypi launch vehicle failed in mid-flight shortly after liftoff", which matched observations of viewers on the ground. 13 CubeSat spacecraft were on board; the primary payload was from the University of Hawaii, two were a part of a NASA's Launch Services Program ELaNa mission, and eight were the EDSN constellation from NASA's Ames Research Center.
ORS-5
On 26 August 2017 the Operationally Responsive Space-5 (ORS-5) satellite was launched from Space Launch Complex 46 at Cape Canaveral Air Force Station in Florida. An Orbital ATK Minotaur IV rocket lifted SensorSat into low Earth orbit. A second Orion (rocket stage) was used to push SensorSat into equatorial orbit. Its mission is situational awareness, to scan the geosynchronous belt for any new geosynchronous satellites, as well as for space junk that may threaten existing geosynchronous satellites.
References
External links
Official Operationally Responsive Space Office (ORS) Site
declared Mission Ready January 3, 2012
United States Department of Defense agencies
Equipment of the United States Space Force | Operationally Responsive Space Office | Astronomy | 877 |
59,853,673 | https://en.wikipedia.org/wiki/Deferrisoma | Deferrisoma is a genus of bacteria from the phylum Thermodesulfobacteriota.
See also
List of bacterial orders
List of bacteria genera
References
Thermodesulfobacteriota
Bacteria genera | Deferrisoma | Biology | 46 |
42,736,966 | https://en.wikipedia.org/wiki/Critical%20theory | Critical theory is a social, historical, and political school of thought and philosophical perspective which centers on analyzing and challenging systemic power relations in society, arguing that knowledge, truth, and social structures are fundamentally shaped by power dynamics between dominant and oppressed groups. Beyond just understanding and critiquing these dynamics, it explicitly aims to transform society through praxis and collective action with an explicit sociopolitical purpose.
Critical theory's main tenets center on analyzing systemic power relations in society, focusing on the dynamics between groups with different levels of social, economic, and institutional power. Unlike traditional social theories that aim primarily to describe and understand society, critical theory explicitly seeks to critique and transform it. Thus, it positions itself as both an analytical framework and a movement for social change. Critical theory examines how dominant groups and structures influence what society considers objective truth, challenging the very notion of pure objectivity and rationality by arguing that knowledge is shaped by power relations and social context. Key principles of critical theory include examining intersecting forms of oppression, emphasizing historical contexts in social analysis, and critiquing capitalist structures. The framework emphasizes praxis (combining theory with action) and highlights how lived experience, collective action, ideology, and educational systems play crucial roles in maintaining or challenging existing power structures.
The historical evolution of critical theory traces back to the first generation of the Frankfurt School in the 1920s. Figures like Max Horkheimer, Theodor Adorno, Herbert Marcuse, and others sought to expand traditional Marxist analysis by incorporating insights from psychology, culture, and philosophy, moving beyond pure economic determinism. Their work was significantly influenced by Freud’s psychoanalytic theories, particularly how subjective experience shaped human consciousness, behavior, and social reality. Freud's concept that an individual's lived experience could differ dramatically from objective reality aligned with critical theory's critique of positivism, science, and pure rationality.
Critical theory continued to evolve beyond the first generation of the Frankfurt School. Jürgen Habermas, often identified with the second generation, shifted the focus toward communication and the role of language in social emancipation. Around the same time, post-structuralist and postmodern thinkers, including Michel Foucault and Jacques Derrida, were reshaping academic discourse with critiques of knowledge, meaning, power, institutions, and social control with deconstructive approaches that further challenged assumptions about objectivity and truth. Though neither Foucault nor Derrida belonged formally to the Frankfurt School tradition, their works profoundly influenced later formulations of critical theory. Collectively, the post-structuralist and postmodern insights expanded the scope of critical theory, weaving cultural and linguistic critiques into its Marxian roots.
With the emigration of Herbert Marcuse, contemporary critical theory has expanded to the United States and today it covers a wide range of social critique within economics, ethics, history, law, politics, psychology, and sociology, with a diverse list of subjects including critical animal studies, critical criminology, dependency theory and imperialism studies, critical environmental justice, feminist theory and gender studies, critical historiography, intersectionality, critical legal studies, critical pedagogy, postcolonialism, critical race theory, queer theory, and critical terrorism studies. Modern critical theory represents a movement away from Marxism’s purely economic analysis to a broader examination of social and cultural power structures with the incorporation and transformation of Freudian concepts and postmodernism, while retaining Marxism’s emphasis on analyzing how dominant groups and systems shape and control society through exploitation and oppression along with social and political praxis, the adaptation and reformulation of multiple Marxian conceptual frameworks (including alienation, reification, ideology, emancipation, base and superstructure), and a general skepticism towards and critique of capitalism.
Criticism of critical theory have come from various intellectual perspectives. Critics have raised concerns about critical theory’s reliance on Marxist revisionism and its frequent emphasis on subjective narratives, which can sometimes be at odds with empirical methodologies. They also point to issues of circular reasoning and a lack of falsifiability in some critical theory arguments, as well as an epistemological and methodological stance that challenges or conflicts with traditional scientific methods and ideals of rationality and objectivity.
History
Max Horkheimer first defined critical theory () in his 1937 essay "Traditional and Critical Theory", as a social theory oriented toward critiquing and changing society as a whole, in contrast to traditional theory oriented only toward understanding or explaining it. Wanting to distinguish critical theory as a radical, emancipatory form of Marxist philosophy, Horkheimer critiqued both the model of science put forward by logical positivism, and what he and his colleagues saw as the covert positivism and authoritarianism of orthodox Marxism and Communism. He described a theory as critical insofar as it seeks "to liberate human beings from the circumstances that enslave them". Critical theory involves a normative dimension, either by criticizing society in terms of some general theory of values or norms (oughts), or by criticizing society in terms of its own espoused values (i.e. immanent critique). Significantly, critical theory not only conceptualizes and critiques societal power structures, but also establishes an empirically grounded model to link society to the human subject. It defends the universalist ambitions of the tradition, but does so within a specific context of social-scientific and historical research.
The core concepts of critical theory are that it should:
be directed at the totality of society in its historical specificity (i.e., how it came to be configured at a specific point in time)
improve understanding of society by integrating all the major social sciences, including geography, economics, sociology, history, political science, anthropology, and psychology
Postmodern critical theory is another major product of critical theory. It analyzes the fragmentation of cultural identities in order to challenge modernist-era constructs such as metanarratives, rationality, and universal truths, while politicizing social problems "by situating them in historical and cultural contexts, to implicate themselves in the process of collecting and analyzing data, and to relativize their findings".
Marx
Marx explicitly developed the notion of critique into the critique of ideology, linking it with the practice of social revolution, as stated in the 11th section of his Theses on Feuerbach: "The philosophers have only interpreted the world, in various ways; the point is to change it." In early works, including The German Ideology, Marx developed his concepts of false consciousness and of ideology as the interests of one section of society masquerading as the interests of society as a whole.
Adorno and Horkheimer
One of the distinguishing characteristics of critical theory, as Theodor W. Adorno and Max Horkheimer elaborated in their Dialectic of Enlightenment (1947), is an ambivalence about the ultimate source or foundation of social domination, an ambivalence that gave rise to the "pessimism" of the new critical theory about the possibility of human emancipation and freedom. This ambivalence was rooted in the historical circumstances in which the work was originally produced, particularly the rise of Nazism, state capitalism, and culture industry as entirely new forms of social domination that could not be adequately explained in the terms of traditional Marxist sociology.
For Adorno and Horkheimer, state intervention in the economy had effectively abolished the traditional tension between Marxism's "relations of production" and "material productive forces" of society. The market (as an "unconscious" mechanism for the distribution of goods) had been replaced by centralized planning.
Contrary to Marx's prediction in the Preface to a Contribution to the Critique of Political Economy, this shift did not lead to "an era of social revolution" but to fascism and totalitarianism. As a result, critical theory was left, in Habermas's words, without "anything in reserve to which it might appeal, and when the forces of production enter into a baneful symbiosis with the relations of production that they were supposed to blow wide open, there is no longer any dynamism upon which critique could base its hope". For Adorno and Horkheimer, this posed the problem of how to account for the apparent persistence of domination in the absence of the very contradiction that, according to traditional critical theory, was the source of domination itself.
Habermas
In the 1960s, Habermas, a proponent of critical social theory, raised the epistemological discussion to a new level in his Knowledge and Human Interests (1968), by identifying critical knowledge as based on principles that differentiated it either from the natural sciences or the humanities, through its orientation to self-reflection and emancipation. Although unsatisfied with Adorno and Horkheimer's thought in Dialectic of Enlightenment, Habermas shares the view that, in the form of instrumental rationality, the era of modernity marks a move away from the liberation of enlightenment and toward a new form of enslavement. In Habermas's work, critical theory transcended its theoretical roots in German idealism, and progressed closer to American pragmatism.
Habermas's ideas about the relationship between modernity and rationalization are in this sense strongly influenced by Max Weber. He further dissolved the elements of critical theory derived from Hegelian German idealism, though his epistemology remains broadly Marxist. Perhaps his two most influential ideas are the concepts of the public sphere and communicative action, the latter arriving partly as a reaction to new post-structural or so-called "postmodern" challenges to the discourse of modernity. Habermas engaged in regular correspondence with Richard Rorty, and a strong sense of philosophical pragmatism may be felt in his thought, which frequently traverses the boundaries between sociology and philosophy.
Modern critical theorists
Contemporary philosophers and researchers who have focused on understanding and critiquing critical theory include Nancy Fraser, Axel Honneth, Judith Butler, and Rahel Jaeggi. Honneth is known for his works Pathology of Reason and The Legacy of Critical Theory, in which he attempts to explain critical theory's purpose in a modern context. Jaeggi focuses on both critical theory's original intent and a more modern understanding that some argue has created a new foundation for modern usage of critical theory. Butler contextualizes critical theory as a way to rhetorically challenge oppression and inequality, specifically concepts of gender.
Honneth established a theory that many use to understand critical theory, the theory of recognition. In this theory, he asserts that in order for someone to be responsible for themselves and their own identity they must be also recognized by those around them: without recognition in this sense from peers and society, individuals can never become wholly responsible for themselves and others, nor experience true freedom and emancipation—i.e., without recognition, the individual cannot achieve self-actualization.
Like many others who put stock in critical theory, Jaeggi is vocal about capitalism's cost to society. Throughout her writings, she has remained doubtful about the necessity and use of capitalism in regard to critical theory. Most of Jaeggi's interpretations of critical theory seem to work against the foundations of Habermas and follow more along the lines of Honneth in terms of how to look at the economy through the theory's lens. She shares many of Honneth's beliefs, and many of her works try to defend them against criticism Honneth has received.
To provide a dialectical opposite to Jaeggi's conception of alienation as 'a relation of relationlessness', Hartmut Rosa has proposed the concept of resonance. Rosa uses this term to refer to moments when late modern subjects experience momentary feelings of self-efficacy in society, bringing them into a temporary moment of relatedness with some aspect of the world. Rosa describes himself as working within the critical theory tradition of the Frankfurt School, providing an extensive critique of late modernity through his concept of social acceleration. However his resonance theory has been questioned for moving too far beyond the Adornoian tradition of "looking coldly at society".
Schools and Derivates
Postmodern critical social theory
Focusing on language, symbolism, communication, and social construction, critical theory has been applied in the social sciences as a critique of social construction and postmodern society.
While modernist critical theory (as described above) concerns itself with "forms of authority and injustice that accompanied the evolution of industrial and corporate capitalism as a political-economic system", postmodern critical theory politicizes social problems "by situating them in historical and cultural contexts, to implicate themselves in the process of collecting and analyzing data, and to relativize their findings". Meaning itself is seen as unstable due to social structures' rapid transformation. As a result, research focuses on local manifestations rather than broad generalizations.
Postmodern critical research is also characterized by the crisis of representation, which rejects the idea that a researcher's work is an "objective depiction of a stable other". Instead, many postmodern scholars have adopted "alternatives that encourage reflection about the 'politics and poetics' of their work. In these accounts, the embodied, collaborative, dialogic, and improvisational aspects of qualitative research are clarified."
The term critical theory is often appropriated when an author works in sociological terms, yet attacks the social or human sciences, thus attempting to remain "outside" those frames of inquiry. Michel Foucault has been described as one such author. Jean Baudrillard has also been described as a critical theorist to the extent that he was an unconventional and critical sociologist; this appropriation is similarly casual, holding little or no relation to the Frankfurt School. In contrast, Habermas is one of the key critics of postmodernism.
Communication studies
When, in the 1970s and 1980s, Habermas redefined critical social theory as a study of communication, with communicative competence and communicative rationality on the one hand, and distorted communication on the other, the two versions of critical theory began to overlap to a much greater degree than before.
Critical disability theory
Critical legal studies
Immigration studies
Critical theory can be used to interpret the right of asylum and immigration law.
Critical finance studies
Critical finance studies apply critical theory to financial markets and central banks.
Critical management studies
Critical international relations theory
Critical race theory
Critical pedagogy
Critical theorists have widely credited Paulo Freire for the first applications of critical theory to education/pedagogy, considering his best-known work to be Pedagogy of the Oppressed, a seminal text in what is now known as the philosophy and social movement of critical pedagogy. Dedicated to the oppressed and based on his own experience helping Brazilian adults learn to read and write, Freire includes a detailed class analysis in his exploration of the relationship between the colonizer and the colonized. In the book, he calls traditional pedagogy the "banking model of education", because it treats the student as an empty vessel to be filled with knowledge. He argues that pedagogy should instead treat the learner as a co-creator of knowledge.
In contrast to the banking model, the teacher in the critical-theory model is not the dispenser of all knowledge, but a participant who learns with and from the students—in conversation with them, even as they learn from the teacher. The goal is to liberate the learner from an oppressive construct of teacher versus student, a dichotomy analogous to colonizer and colonized. It is not enough for the student to analyze societal power structures and hierarchies, to merely recognize imbalance and inequity; critical theory pedagogy must also empower the learner to reflect and act on that reflection to challenge an oppressive status quo.
Critical consciousness
Critical university studies
Critical psychology
Critical criminology
Critical animal studies
Critical social work
Critical ethnography
Critical data studies
Critical environmental justice
Critical environmental justice applies critical theory to environmental justice.
Criticism
While critical theorists have often been called Marxist intellectuals, their tendency to denounce some Marxist concepts and to combine Marxian analysis with other sociological and philosophical traditions has resulted in accusations of revisionism by Orthodox Marxist and by Marxist–Leninist philosophers. Martin Jay has said that the first generation of critical theory is best understood not as promoting a specific philosophical agenda or ideology, but as "a gadfly of other systems".
Critical theory has been criticized for not offering any clear road map to political action (praxis), often explicitly repudiating any solutions. Those objections mostly apply to first-generation Frankfurt School, while the issue of politics is addressed in a much more assertive way in contemporary theory.
Another criticism of critical theory "is that it fails to provide rational standards by which it can show that it is superior to other theories of knowledge, science, or practice." Rex Gibson argues that critical theory suffers from being cliquish, conformist, elitist, immodest, anti-individualist, naive, too critical, and contradictory. Hughes and Hughes argue that Habermas' theory of ideal public discourse "says much about rational talkers talking, but very little about actors acting: Felt, perceptive, imaginative, bodily experience does not fit these theories".
Some feminists argue that critical theory "can be as narrow and oppressive as the rationalization, bureaucratization, and cultures they seek to unmask and change.
Critical theory's language has been criticized as being too dense to understand, although "Counter arguments to these issues of language include claims that a call for clearer and more accessible language is anti-intellectual, a new 'language of possibility' is needed, and oppressed peoples can understand and contribute to new languages."
Bruce Pardy, writing for the National Post, argued that any challenges to the "legitimacy [of critical theory] can be interpreted as a demonstration of their [critical theory's proponents'] thesis: the assertion of reason, logic and evidence is a manifestation of privilege and power. Thus, any challenger risks the stigma of a bigoted oppressor."
Robert Danisch, writing for The Conversation, argued that critical theory, and the modern humanities more broadly, focus too much on criticizing the current world rather than trying to make a better world.
See also
Modernism
Antipositivism
Critical military studies
Cultural studies
Information criticism
Marxist cultural analysis
Outline of critical theory
Popular culture studies
Outline of organizational theory
Postcritique
Quare theory
Lists
List of critical theorists
List of works in critical theory
Journals
Constellations
Representations
Critical Inquiry
Telos
Law and Critique
References
Footnotes
Works cited
Bibliography
"Problematizing Global Knowledge." Theory, Culture & Society 23(2–3). 2006. .
Calhoun, Craig. 1995. Critical Social Theory: Culture, History, and the Challenge of Difference. Blackwell. – A survey of and introduction to the current state of critical social theory.
Charmaz, K. 1995. "Between positivism and postmodernism: Implications for methods." Studies in Symbolic Interaction 17:43–72.
Conquergood, D. 1991. "Rethinking ethnography: Towards a critical cultural politics." Communication Monographs 58(2):179–94. .
Corchia, Luca. 2010. La logica dei processi culturali. Jürgen Habermas tra filosofia e sociologia. Genova: Edizioni ECIG. .
Dahms, Harry, ed. 2008. No Social Science Without Critical Theory, (Current Perspectives in Social Theory 25). Emerald/JAI.
Gandler, Stefan. 2009. Fragmentos de Frankfurt. Ensayos sobre la Teoría crítica. México: 21st Century Publishers/Universidad Autónoma de Querétaro. .
Geuss, Raymond. 1981. The Idea of a Critical Theory. Habermas and the Frankfurt School. Cambridge University Press. .
Honneth, Axel. 2006. La société du mépris. Vers une nouvelle Théorie critique, La Découverte. .
Horkheimer, Max. 1982. Critical Theory Selected Essays. New York: Continuum Publishing.
Morgan, Marcia. 2012. Kierkegaard and Critical Theory. New York: Lexington Books.
Rolling, James H. 2008. "Secular blasphemy: Utter(ed) transgressions against names and fathers in the postmodern era." Qualitative Inquiry 14(6):926–48. – An example of critical postmodern work.
Sim, Stuart, and Borin Van Loon. 2001. Introducing Critical Theory. . – A short introductory volume with illustrations.
Thomas, Jim. 1993. Doing Critical Ethnography. London: Sage. pp. 1–5 & 17–25.
Tracy, S. J. 2000. "Becoming a character for commerce: Emotion labor, self subordination and discursive construction of identity in a total institution." Management Communication Quarterly 14(1):90–128. – An example of critical qualitative research.
Willard, Charles Arthur. 1982. Argumentation and the Social Grounds of Knowledge. University of Alabama Press.
— 1989. A Theory of Argumentation. University of Alabama Press.
— 1996. Liberalism and the Problem of Knowledge: A New Rhetoric for Modern Democracy. Chicago: University of Chicago Press.
Chapter 9. Critical Theory
External links
Gerhardt, Christina. "Frankfurt School". The International Encyclopedia of Revolution and Protest. Ness, Immanuel (ed). Blackwell Publishing, 2009. Blackwell Reference Online.
"Theory: Death Is Not the End" N+1 magazine's short history of academic Critical Theory.
Critical Legal Thinking A Critical Legal Studies website which uses Critical Theory in an analysis of law and politics.
L. Corchia, Jürgen Habermas. A Bibliography: works and studies (1952–2013), Pisa, Edizioni Il Campano – Arnus University Books, 2013, 606 pages.
Sim, S.; Van Loon, B. (2009). Introducing Critical Theory: A Graphic Guide. Icon Books Ltd.
Archival collections
Guide to the Critical Theory Offprint Collection. Special Collections and Archives, The UC Irvine Libraries, Irvine, Cali Guide to the Critical Theory Institute Audio and Video Recordings, University of California, Irvine. Special Collections and Archives, The UC Irvine Libraries, Irvine, California.
University of California, Irvine, Critical Theory Institute Manuscript Materials. Special Collections and Archives, The UC Irvine Libraries, Irvine, California.
Conflict theory
Humanities
Philosophy of technology
Philosophical schools and traditions
Social philosophy
Political ideologies | Critical theory | Technology | 4,641 |
2,650,348 | https://en.wikipedia.org/wiki/Carl-Zeiss-Stiftung | The Carl-Zeiss-Stiftung (Carl Zeiss Foundation), legally located in Heidenheim an der Brenz and Jena, Germany, and with its administrative headquarters in Stuttgart, is the sole shareholder of the two companies Carl Zeiss AG and Schott AG. It was founded by Ernst Abbe in 1889 and named after his long-term partner Carl Zeiss. The products of these companies include the classic areas of optics and precision mechanisms, as well as glass (including optical glass), optoelectronics, and glass ceramics. The statutes of the foundation emphasize the social responsibility of the companies and the importance of a fair treatment of the employees.
In fiscal year 2007/2008 more than 30,000 people were employed by the foundation's companies and their subsidiaries, with total sales of over 4.9 billion Euros.
Founding
The Carl-Zeiss-Stiftung was founded by the German physicist and mathematician Ernst Abbe. He named it after his late business partner and friend Carl Zeiss, who died in 1888. The deed of foundation dates from May 19, 1889. On 21 May establishment of the foundation was approved by the Grand Duchy of Saxe-Weimar-Eisenach, making it a legal entity. Originally Abbe had intended to transfer his interests in the companies Carl Zeiss and Jenaer Glaswerk Schott & Genossen to the University of Jena, feeling that he had the University to thank for his rise to wealthy entrepreneur. He established the Ministerial Fund for Scientific Purposes in 1886 for this reason; through the fund, he annually donated substantial sums anonymously to the University. In addition, he financed the construction of a University Observatory in 1889 out of his private funds.
The gift of his shares to the University, as originally intended, was not legally possible. Working with representatives of the Sachsen-Weimar state government, the idea of a foundation was formed. The Carl-Zeiss-Stiftung was founded in 1889; Ernst Abbe turned over his shares in these firms, as well as those of Roderich Zeiss, Carl Zeiss's son, to the foundation by 1891. In 1919 Otto Schott also donated his shares to the foundation, giving it the sole proprietorship of the glass works, as well. The act of incorporation lasted until 1896; an amendment governing grants to the University, followed in 1900.
In Paragraph 1 of this act of incorporation lays down the following general purposes of the foundation:
Economic security of both firms owned by the foundation
Social responsibility to the employees
Advancing the interests of precision industries
Involvement in community facilities for the good of the working people of Jena
Advancing natural and mathematical science in research and teaching
The act also includes rules of organization of the foundation, particularly regarding the foundations divisions, business operations, and questions of social and labor law. The legal establishment and enforceability of workers' rights were notable for the time, visionary, and trend-setting. The peculiarity of the original legal structure of the Carl-Zeiss-Stiftung was its definition as a business entity, rather than its current form as holding company. The foundation was thus the manager of both of its companies, rather than holder of ownership of independent companies. The foundation was governed by the Culture Ministry of Weimar; from there came the foundation's "commissar", who led the management of the businesses. The foundation's board was appointed by its management. The first commissar was Carl Rothe (until 1896), followed by Max Vollert who remained in office until 1911. Then Friedrich Ebsen occupied the office until 1933.
References
External links
Carl Zeiss Foundation
Foundations based in Germany
Companies based in Thuringia
Photography companies of Germany
Carl Zeiss AG
Technology companies established in 1889
1889 establishments in Germany | Carl-Zeiss-Stiftung | Astronomy | 769 |
53,738,650 | https://en.wikipedia.org/wiki/The%20Doctor%20Falls | "The Doctor Falls" is the twelfth and final episode of the tenth series, and 843rd episode overall, of the British science fiction television series Doctor Who. It was written by Steven Moffat, directed by Rachel Talalay, and was broadcast on 1 July 2017 on BBC One. It is the second episode of a two-part story, the first part being "World Enough and Time".
As a continuation of the previous episode, "The Doctor Falls" concludes the first televised multi-Master story of the show, as well as the origin of the Mondasian Cybermen. In the episode, the Doctor must save himself and the remaining human population of a gigantic colony ship from Mondas, while also dealing with two different incarnations of the Master at once. The episode features a cameo from the First Doctor, now portrayed by David Bradley. He had previously played William Hartnell, the original First Doctor actor, in the 2013 Doctor Who docudrama An Adventure in Space and Time.
The episode was watched by 5.30 million viewers and received much critical praise, with many deeming it a satisfying end to the tenth series. Aspects of the episode that were met with the most praise were Moffat’s script, Talalay’s direction and Capaldi’s performance.
Plot
Continuing from the previous episode, the Master and Missy capture the Doctor, but he had earlier surreptitiously reprogrammed the Cybernet to target Time Lords as well, forcing them to flee. Nardole arrives in a commandeered shuttlecraft to rescue them. The Doctor is electrocuted by a Cyberman, but is saved by Bill.
They evacuate to a higher level of the ship containing a solar farm populated by children and a few adults. The Doctor recovers, but suppresses the early signs of regeneration. Bill initially remains unaware of her transformation, her strong mind acting like a perception filter, until one of the children inadvertently reveals the truth to her. Bill sheds a tear, which the Doctor calls a hopeful sign. Missy and the Master discover a camouflaged lift. They call for it, but an upgraded Cyberman arrives, which the group destroys. The Doctor warns that the time dilation affords the Cybermen more time to evolve and strategize.
Nardole discovers the floor directly below the solar farm contains fuel pipes. He is able to trigger controlled explosions, which are used to defeat the Cybermen's initial attack. The Doctor instructs Nardole to lead the human community to a solar farm on another floor and remain there to safeguard them. Bill stays to fight with the Doctor. Despite the Doctor's impassioned plea, Missy and the Master abandon him, intending to take the lift to the lowest level and escape in the Master's TARDIS. Missy, however, changes her mind and stabs the Master. He retaliates by shooting her in the back with his laser screwdriver, telling her she will not regenerate. Both laugh over the irony of their mutual betrayal before the Master departs.
An army of Cybermen arrive, but are warded off by the Doctor until he falls after being shot. Surrounded, the Doctor ignites all the fuel pipes, engulfing the farm in a fireball and destroying the Cybermen. The Doctor lies still as Bill kneels beside him. Heather appears, having found Bill through her tears. She saves Bill by transforming her into an entity like herself. They leave the Doctor inside his TARDIS, and Heather invites Bill to explore the universe with her.
The TARDIS arrives in a snowy landscape and the Doctor awakens, and starts regenerating. Refusing to keep continually changing, he emerges and seemingly stops his regeneration. Within, the cloister bell sounds an alarm as the Doctor encounters his original incarnation.
Continuity
During the final battle, the Doctor lists the various sites of his encounters with Cybermen: Mondas (The Tenth Planet), Telos (The Tomb of the Cybermen), Planet 14 (The Invasion), Voga (Revenge of the Cybermen), Canary Wharf ("Doomsday"), and the Moon (The Moonbase). He also mentions Marinus, a reference to the events of Grant Morrison's Sixth Doctor comic The World Shapers, in which that planet's Voord evolve into Cybermen (though that story also suggests that Mondas, Planet 14, and Marinus are all the same planet).
Missy mentions that the Doctor once died in a fall, referring to events in Logopolis (1981), in which one of her previous incarnations causes the Fourth Doctor to fall from a radio telescope tower.
The Doctor flashes back to several of his former companions from the revived series, who each say "Doctor", similar to what the Fourth Doctor experienced prior to his regeneration in Logopolis. When the Doctor awakens, he quotes himself from previous regenerations: "Sontarans perverting the course of human history" (the Fourth Doctor in Robot), "I don't want to go!" (the Tenth Doctor in "The End of Time"), and "When the Doctor was me..." (the Eleventh Doctor in "The Time of the Doctor").
The First Doctor's dialogue "You may be a doctor, but I am the Doctor. The original, you might say" references lines spoken by the Fourth Doctor to Harry Sullivan in Robot, and by the First Doctor to Tegan Jovanka in The Five Doctors.
Production
The read through for this episode took place on 21 February 2017. On 6 March 2017 the BBC stated that the work on the final two episodes of the series had begun, "World Enough and Time" and this episode, with Rachel Talalay returning to direct her third consecutive series finale. Filming for the episodes and the series as a whole concluded on 7 April 2017. The final scene involving David Bradley was filmed as part of the filming of the Christmas Special in June 2017.
Casting
David Bradley appeared at the episode's conclusion as the First Doctor. He had previously portrayed William Hartnell, the First Doctor's actor, in the docudrama An Adventure in Space and Time and appeared as the villain Solomon in "Dinosaurs on a Spaceship", as well as voicing the character of Shansheeth Blue in Death of the Doctor in the Doctor Who spin-off series The Sarah Jane Adventures.
Michelle Gomez had previously announced that she was exiting the role of Missy following the conclusion of series ten.
Broadcast and reception
The episode was watched by 3.75 million viewers overnight, an audience share of 25.3%. The episode received 5.30 million views overall, and it received an Appreciation Index of 83.
Critical reception
"The Doctor Falls" received overwhelmingly positive reviews, with most reviewers finding it a fitting end to the tenth series. The episode holds a score of 100% on Rotten Tomatoes, with the site consensus reading "'The Doctor Falls' offers a dramatic and satisfying end for this iteration of the show's ever-evolving hero." Praise was directed at Moffat's script, Talalay's direction, and Capaldi's performance.
Alasdair Wilkins from The A.V. Club called the episode a "perfect finale", saying that the Twelfth Doctor is a Doctor who knows who he is, portrayed by an actor who knows exactly how he wants to play the part of the character, both of which are played into the narrative of the story and blending into the storyline of the Doctor refusing to regenerate. He complimented how the multiple storylines of the series were wrapped up and brought to a satisfying conclusion, as well as respecting the reality of the character's emotions, which were performed with only a couple of small missteps.
Scott Collura of IGN also praised the dynamic between the two Masters, describing the relationship as a mixture of "brother-sister and boyfriend-girlfriend" and its resultant complexities, and how the intentions of the previous incarnation of the Master was to draw Missy back into the traditional evil manner of the character. He stated that the story made enough sense that "Moffat doesn't really even need to write it on the page". He complimented the appearance of David Bradley as the First Doctor, but stated that extending the storyline of the regeneration out over the two episodes of the finale, as well as the Christmas special, was a great concept but did not work in the context of the episode.
Giving the episode a perfect score, Patrick Mulkern of Radio Times singled out the performances as one of the strong points about the episode, saying that Capaldi, Simm and Gomez worked perfectly well together within the episode. He stated that Capaldi was as magnificent as he had been through the series, and that "The Doctor Falls" was an episode dedicated to him, and how he "stands tall" among the competition of Simm's and Gomez's acting. He stated that Simm's Master was not the "loon" that was portrayed seven years ago, but complimented him nonetheless, and that Gomez's portrayal of Missy and the character's soul-searching was "simply superb".
Daniel Jackson of the Daily Mirror also gave the episode a perfect score, and felt the episode was an immensely satisfying conclusion with great storytelling and epic performances, stating that with all the teasers, build up and trailers that had been released in preparation for the episode, "The Doctor Falls" could have resulted in failure, but he complimented how well it turned out. He stated that the episode was an "immensely satisfying, packed, heart string tugging" conclusion to the series, that was the result of "clever storytelling and tremendous acting". He stated that Capaldi and his performance in the episode "simply shines", and that the Twelfth Doctor had never had a better episode through his era.
The episode received a nomination in the Best Special and Visual Effects category at the 2019 BAFTA Cymru Awards.
References
External links
2017 British television episodes
Fiction about time dilation
Fiction about black holes
Cybermen television stories
Doctor Who multi-Doctor stories
First Doctor serials
The Master (Doctor Who) television stories
Television episodes written by Steven Moffat
Twelfth Doctor episodes
Doctor Who multi-Master stories
Television episodes set in hospitals
Television episodes set in outer space
Television episodes set in the 1980s
Fiction set in 1986 | The Doctor Falls | Physics | 2,104 |
56,849,025 | https://en.wikipedia.org/wiki/Left-right%20asymmetry | In developmental biology, left-right asymmetry (LR asymmetry) is the process in early embryonic development that breaks the normal symmetry in the bilateral embryo. In vertebrates, left-right asymmetry is established early in development at a structure called the left-right organizer (the name of which varies between species) and leads to activation of different signalling pathways on the left and right of the embryo. This in turn causes several organs in adults to develop LR asymmetry, such as the tilt of the heart, the different number of lung lobes on each side of the body, and the position of the stomach and spleen on the right side of the body. If this process does not occur correctly in humans it can result in heterotaxy or situs inversus.
LR asymmetry is pervasive throughout all animals, including invertebrates. Examples of invertebrate LR asymmetry include the large and small claws of the fiddler crab, asymmetrical gut coiling in Drosophila melanogaster, and dextral (clockwise) and sinistral (counterclockwise) coiling of gastropods. This asymmetry can be restricted to a specific organ or feature, as in the crab claws, or be expressed throughout the entire body as in snails.
Developmental basis
Different species have evolved different mechanisms of LR patterning. For example, cilia are critical for LR patterning in many vertebrate species such as humans, rodents, fish and frog, but other species, such as reptiles, birds and pigs develop LR asymmetry without cilia.
Cilia dependent vertebrates
The name of the LR organiser varies between species, and thus includes the node in mice, the gastrocoel roof plate in frog and Kupffer’s vesicle in zebrafish. In each case the LR organizer is found on the dorsal side of the embryo and each organizer cell has a single cilia located on the posterior side of the cell. The combination of location of cells of the dorsal surface combined with the posterior location of the cilia means that when the cilia rotate it creates a left-ward flow across the surface of the organizer. The flow causes loss of Cerl2 and increased Nodal expression on the left side of the organizer, although there is some debate whether this occurs due to a chemical/protein signal or due to the cells physically sensing the flow. In either case, the signal is then transferred to the left Lateral plate mesoderm where it activates a further signalling cascade of genes including Nodal, Pitx2 and Lefty2.
Cilia independent vertebrates
In chickens, LR asymmetry is established at a structure called Hensen’s node. Unlike most other vertebrates, this process is not thought to involve cilia as (i) Hensen’s node does not have motile cilia and (ii) unlike other species, mutations that affect cilia formation do not cause laterality defects in chicken. Instead, chickens establish LR asymmetry through asymmetric cell rearrangements which results in a leftward movement of cells near the Hensen’s node.
Another study has found that pigs do not have cilia within their left right organiser, suggesting pigs also have an alternative cilia independent mechanism for establishing LR asymmetry.
Non-vertebrate deuterostomes
Recently, work has shown that the Nodal-Pitx2 pathway is present and functional in the non-vertebrate deuterostomes (tunicates, sea urchins). In tunicate (ascidian) Ciona intestinalis and Halocynthia roretzi, Nodal is expressed on the left side of the developing embryo and leads to downstream expression of Pitx2. At earlier stages, similar H+/K+ ATPase ion channels are reported to be necessary for correct left-right patterning. While the role of cilia here is still unclear, one study observes that large-scale embryonic movements are required for left-right determination in H. roretzi, and that this movement is possibly achieved through ciliary movements.
In the sea urchin, Nodal is expressed on the right side of the embryo, in contrast to the tunicate and vertebrate condition on the left side. Because protostomes appear to also express Nodal on their right side instead of the left (discussed below), some have suggested that this lends further evidence for the dorsoventral inversion hypothesis.
Protostomes
Ecdysozoa
While D. melanogaster and nematode Caenorhabditis elegans do show left-right asymmetry, the Nodal signaling pathway itself is absent in Ecdysozoa. Instead, cytoskeletal regulators such as Myo31DF, a type ID unconventional myosin, have been found to control left-right asymmetry in organ systems such as genitalia.
Lophotrochozoa
Unlike in Ecdysozoa, the Nodal-Pitx2 pathways have been identified in many lineages within the Lophotrochozoans. When found in brachiopods and molluscs, these genes are asymmetrically expressed on the right. Platyhelminthes, annelids, and nermeteans lack a Nodal orthologue and instead only express Pitx2, which was expressed in association to the nervous system.
Whole body left-right asymmetry in gastropods
Whole body inversion is observed as chiral (dextral, sinistral) coiling in gastropods. While dextral coiling is the most common as it appears in 90-99% of living species, sinistral species still have arisen many times.
Developmental basis of shell coiling
Gastropods undergo spiral cleavage, a feature commonly seen in lophotrochozoans. As the embryo divides, quartets of cells are oriented at angles to each other. In the snail Lymnaea stagnalis, the direction of rotation during the first cell division signals whether the adult will show dextral or sinistral coiling, At the third cleavage (8-cell stage), spindles in dextral snails are inclined clockwise whereas they are counterclockwise in sinistral snails. Furthermore, injecting L. peregra sinistral eggs with the cytoplasm of dextral eggs before the second polar body formation will reverse the polarity of the sinistral embryos. These data show that chirality is heritable and maternally deposited in Lymnaea.
Several studies have begun to investigate the molecular basis of this inheritance. Nodal and Pitx2 are expressed on different sides of the L. stagnalis embryo depending on its chirality – right for dextral, left for sinistral. Downstream of Nodal, decapentaplegic (dpp), shows the same expression pattern. In limpets (gastropods without coiled shells) dpp is expressed symmetrically in Patella vulgata and Nipponacmea fuscoviridis. Additionally, in N. fuscoviridis, dpp has been shown to drive cell proliferation
Upstream of Nodal, Lsdia1/2 have been implicated in controlling L. stagnalis chirality. Davison et al. (2016) mapped the “chirality locus” to a 0.4 Mb region and determined that Lsdia2 is the likely candidate for determining dextral or sinistral coiling. This is a diaphanous-related formin gene involved in cytoskeleton formation. Dextral embryos treated with drugs that inhibited formin activity phenocopied the sinistral condition. Concurrent work from Kuroda et al. (2016) identified the same Lsdia2 gene (called Lsdia1 in their study) but failed to reproduce the formin inhibition results in the Davison et al. study. Additionally, Kuroda et al. (2016) did not find asymmetrically expressed Lsdia2 as was seen in the Davison et al. (2016) study.
See also
Fluctuating asymmetry
Symmetry breaking and cortical rotation
References
Asymmetry
Animal anatomy | Left-right asymmetry | Physics | 1,727 |
3,212,386 | https://en.wikipedia.org/wiki/Active%20living | Active living is a lifestyle that integrates physical activity into everyday routines, such as walking to the store or biking to work. Active living is not a formalized exercise program or routine, but instead means to incorporate physical activity, which is defined as any form of movement, into everyday life. Active living brings together urban planners, architects, transportation engineers, public health professionals, activists and other professionals to build places that encourage active living and physical activity. One example includes efforts to build sidewalks, crosswalks, pedestrian crossing signals, and other ways for children to walk safely to and from school, as seen in the Safe Routes to School program. Recreational opportunities (parks, fitness centres etc.) close to the home or workplace, walking trails, and bike lanes for transportation also contribute to a more active lifestyle. Active living includes any physical activity or recreation activity and contributes to a healthier lifestyle. Furthermore, active living addresses health concerns, such as obesity and chronic disease, by helping people have a physically active lifestyle. Communities that support active living gain health benefits, economic advantages, and improved quality of life.
For achieving active living, people need at least 150 minutes of moderate physical activity or 75 minutes of strong physical activity every week.
History
Active living is a growing field that emerged from the early work of the Centers for Disease Control and Prevention (CDC) with the release of the Surgeon's General Report on Physical Activity and Health in 1996. In 1997, the CDC began the development of an initiative called Active Community Environments (ACEs) coordinated by Rich Killingsworth (the founding director of active living by Design ) and Tom Schmid, a senior health scientist. The main programming thrust of ACEs was an emerging initiative called Safe Routes to School that was catalysed by a program designed by Rich Killingsworth and Jessica Shisler at CDC called KidsWalk-to-School. This program provided much-needed attention to the connections of the built environment and health, especially obesity and physical inactivity. In 2000, Robert Wood Johnson Foundation formally launched their active living initiative. Led by Karen Gerlach, Marla Hollander, Kate Kraft and Tracy Orleans, this national effort comprised five national programs - Active Living by Design, Active Living Research, Active Living Leadership, Active Living Network and Active for Life. The goals of these programs was multifaceted and included; building the research base, establishing best practices and community models, supporting leadership efforts and connecting multi-sectoral professionals. The overarching goal to develop an understanding of how the built environment impacted physical activity and what could be done to increase physical activity.
Benefits
There are many health related benefits to being physically active and living an active life. Active living can help to reduce the risk of chronic diseases, improve overall health and well-being, reduce stress levels, minimize health related medical costs, help maintain a healthy weight, assist in proper balance and posture and the maintenance of healthy bones and strong muscles. Active living can also improve sleeping patterns and aid in the prevention of risk factors for heart disease such as blood cholesterol levels, diabetes and hypertension.
Running can reduce the level of mortality from many diseases by 27%.
Types of physical activity
There are four types of physical exercises that medical professionals recommend in order to improve and maintain physical abilities: endurance, flexibility, balance, and strength activities.
Endurance activities increase your heart rate and strengthen your heart and lungs. Examples include dancing, skating, climbing stairs, cycling, swimming and brisk walking.
Flexibility activities improve your body's ability to move and assist in keeping your muscles and joints relaxed. Examples include yard work, vacuuming, golf, and stretching - when you wake up, before you exercise and after to prevent injury.
Balance activities reduce the risk of falling and focuses primarily on lower-body strength. Examples include standing up after being seated, Tai Chi, and standing on a single foot.
Strength activities create and maintain muscle, while also keeping bones strong. Examples include raking leaves, carrying groceries, climbing stairs, lifting free weights, and doing push-ups.
Endurance, flexibility, balance, and strength activities can be incorporated into daily routines and promote active living. For example, activities such as household chores and taking the stairs can fit into more than one of the above categories.
Recommendations
In Canada, the Public Health Agency of Canada supported the Canadian Society for Exercise Physiology (CSEP) to review the Canada's Physical Activity Guides, which were updated and replaced with the Get Active Tip Sheets. The Get Active Tip Sheets are broken down into 4 age categories (5–11, 12–17, 18–64, and 65 & older).
The Get Active Tip Sheets recommend that children aged 5–11 and youth aged 12–17 should participate in at least 60 minutes of moderate to vigorous physical activity each day. The recommendation for adults 18–64 and for older adults 65 years and older is at least 2.5 hours of moderate to vigorous physical activity per week. These minutes do not all need to be done at the same time, but the recommendation is a minimum of 10 minutes at a time.
Initiatives
In Canada, there are many active living initiatives currently in place. One of the most well-known programs is the ParticipACTION program, which aims to encourage Canadians to move more and increase their physical activity levels. Their mission statement is "ParticipACTION is the national voice of physical activity and sport participation in Canada. Through leadership in communications, capacity building and knowledge exchange, we inspire and support Canadians to move more." Since the 1970s, ParticipACTION has been motivating Canadians to live actively and participate in sports.
See also
- automobile oriented transportation
Basal metabolic rate - the rate at which the body uses energy while at rest to maintain vital functions such as breathing and keeping warm
- transport on cycle
National Physical Activity Guidelines
Sedentary lifestyle - a lifestyle with a lot of sitting and lying down, with very little to no exercise
Urban vitality - the extent to which a place feels alive or lively
References
Urban planning
Health promotion
Physical exercise
Health and transport | Active living | Engineering | 1,220 |
1,484,838 | https://en.wikipedia.org/wiki/Leaded%20glass | Leaded glass may refer to:
Lead glass, potassium silicate glass which has been impregnated with a small amount of lead oxide in its fabrication
Lead came glasswork, glass panels made by combining multiple small pieces of glass, which may be stained, textured or beveled, with cames or copper foil
Leadlight or leaded lights, decorative windows made of small sections of glass supported in lead cames
Flint glass, an optical glass that has relatively high refractive index and low Abbe number
Glass compositions | Leaded glass | Chemistry | 108 |
33,316,865 | https://en.wikipedia.org/wiki/AdoMet%20MTase | S-adenosylmethionine-dependent methyltransferase (SAM-MTase or AdoMet-MTase) is a conserved protein domain and protein superfamily. SAM-MTase proteins are methyltransferases. There are five protein families within SAM-MTase,
SAM-MTases use S-adenosyl-L-methionine as a substrate for methylation, creating the product S-adenosyl-L-homocysteine.
Structure and subgroups
All SAM-MTases contain a structurally conserved SAM-binding domain consisting of a central seven-stranded beta-sheet that is flanked by three alpha-helices per side of the sheet.
A review published in 2003 divides all methyltransferases into 5 main classes based on the structure of their catalytic domain (fold):
class I: Rossmann-like α/β, the largest subgroup.
class II: TIM β/α-barrel α/β
class III: tetrapyrrole methylase α/β
class IV: SPOUT α/β
class V: SET domain all β
References
Protein families
Protein superfamilies
Protein domains | AdoMet MTase | Biology | 240 |
44,981,512 | https://en.wikipedia.org/wiki/Istanbul%20region%20%28statistical%29 | The Istanbul Region (Turkish: İstanbul Bölgesi) (TR1) is a statistical region in Turkey.
Subregions and provinces
Istanbul Subregion (TR10)
Istanbul Province (TR100)
Age groups
Internal immigration
State register location of Istanbul residents
Marital status of 15+ population by gender
Education status of 15+ population by gender
See also
NUTS of Turkey
References
External links
TURKSTAT
Sources
ESPON Database
Statistical regions of Turkey | Istanbul region (statistical) | Mathematics | 86 |
3,720,440 | https://en.wikipedia.org/wiki/Back%20pressure | Back pressure (or backpressure) is the term for a resistance to the desired flow of fluid through pipes. Obstructions or tight bends create backpressure via friction loss and pressure drop.
In distributed systems in particular event-driven architecture, back pressure is a technique to regulate flow of data, ensuring that components do not become overwhelmed.
Explanation
A common example of backpressure is that caused by the exhaust system (consisting of the exhaust manifold, catalytic converter, muffler and connecting pipes) of an automotive four-stroke engine, which has a negative effect on engine efficiency, resulting in a decrease of power output that must be compensated by increasing fuel consumption.
In a piston-ported two-stroke engine, however, the situation is more complicated, due to the need to prevent unburned fuel/air mixture from passing right through the cylinders into the exhaust. During the exhaust phase of the cycle, backpressure is even more undesirable than in a four-stroke engine, as there is less time available for exhaust and the lack of pumping action from the piston to force the exhaust out of the cylinder. However, since the exhaust port necessarily remains open for a time after scavenging is completed, unburned mixture can follow the exhaust out of the cylinder, wasting fuel and increasing pollution. This can only be prevented if the pressure at the exhaust port is greater than that in the cylinder. Since the timing of this process is determined mainly by exhaust system geometry, which is extremely difficult to make variable, correct timing and therefore optimum engine efficiency can typically only be achieved over a small part of the engine's range of operating speed.
Liquid chromatography
Back pressure is the term used for the hydraulic pressure required to create a flow through a chromatography column in high-performance liquid chromatography, the term deriving from the fact that it is generated by the resistance of the column, and exerts its influence backwards on the pump that must supply the flow. Back-pressure is a useful diagnostic feature of problems with the chromatography column. Rapid chromatography is favoured by columns packed with very small particles, which create high back-pressures. Column designers use "kinetic plots" to show the performance of a column at a constant back-pressure, usually selected as the maximum that a system's pump can reliably produce.
See also
Exhaust pulse pressure charging
Expansion chamber
Scalar quantity
References
Engine technology
Pressure
Piping
Two-stroke engine technology | Back pressure | Physics,Chemistry,Technology,Engineering | 507 |
67,525,912 | https://en.wikipedia.org/wiki/NGC%203608 | NGC 3608 is an elliptical galaxy located in the constellation Leo. It was discovered by William Herschel on March 14, 1784.
NGC 3608 is part of the Leo II Group of galaxies, including NGC 3605 and NGC 3607. It is approximately 13.0 billion years old. There is diffuse X-ray emission coming from this galaxy and NGC 3607, which suggests that the two may be merging.
NGC 3608 has a significant population of globular clusters. The population distribution is bimodal, with "red" and "blue" populations; the blue globular clusters form a majority. The blue globular clusters have a more extended distribution throughout the galaxy. Overall, the globular clusters are aligned along an axis that is not the same as the rest of the stars, which may be further evidence of galaxy interaction with NGC 3607.
A large structure of neutral hydrogen gas known as an H I region, about 130,000 light-years (40 kpc) across, exists some twelve arcminutes (corresponding to about 230,000 light-years, or 70 kpc) away from NGC 3608. It may be associated with the galaxy.
References
External links
Leo (constellation)
3608
Elliptical galaxies
034433 | NGC 3608 | Astronomy | 257 |
22,451,678 | https://en.wikipedia.org/wiki/CeramTec | The CeramTec Group is a developer and manufacturer of products and components made of technical ceramics (also known as advanced technical ceramics). The products are marketed through its own sales companies, among others. They are primarily used in medical technology, automotive engineering, electronics, equipment and mechanical engineering, environmental and energy technology, toolmaking, the chemical industry and the semiconductor industry. The company is headquartered in Plochingen in Baden-Württemberg, Germany.
The company is present around the globe and has production sites and sales offices in the world’s most important markets. In Germany, the main sites are Plochingen, Lauf and Marktredwitz in addition to the company’s other German sites in Ebersbach, Lohmar and Wilhermsdorf.
The company is a member of the Ceramic Industry Association (German: Verband der Keramischen Industrie e.V. - VKI) and the German Ceramic Society.
History
The founding of CeramTec goes back to the year 1903, when the Thomas factories (Thomaswerke) were founded at the Marktredwitz site, and which were taken over by Philipp Rosenthal & Co. AG in 1908. In 1921 Philipp Rosenthal & Co. AG began cooperating with AEG in the development of technical porcelain for early industrial applications of ceramic materials. The two companies intensified this partnership in the area of technical ceramics in 1936, resulting in the foundation of Rosenthal Isolatoren GmbH, also known as RIG.
With the intention of manufacturing technical ceramics, they reorganized their cooperation in 1971. The result was the company Rosenthal Stemag Technische Keramik GmbH, which was renamed Rosenthal Technik AG in 1974. In 1985 Hoechst AG acquired the company and from that point on operated it under the name Hoechst CeramTec AG. Cerasiv GmbH, a company based in Plochingen, took over Hoechst CeramTec AG in 1996 and the newly formed company received the name CeramTec AG.
The site in Lauf an der Pegnitz has its roots in STEMAG AG (Steatit-Magnesia Aktiengesellschaft), founded in 1921. Following an initial incorporation into AEG in 1970, the company merged into Rosenthal Stemag Technische Keramik GmbH in 1971 as part of the reorganization of the partnership between Rosenthal and AEG.
Südplastik Gummi- und Kunststoffverarbeitung GmbH began operations at the Plochingen site in 1951. Feldmühle AG took over the company in 1953, renaming it Südplastik und -keramik GmbH (SPK). Feldmühle AG refocused its ceramic activities in 1991 in the newly founded Cerasiv GmbH, but then quickly sold it in 1992 to Metallgesellschaft AG, which integrated the company into its subsidiary Dynamit Nobel AG. Cerasiv GmbH’s acquisition of Hoechst CeramTec AG followed in 1996, resulting in the founding of CeramTec AG as a Metallgesellschaft AG (mg technologies AG) company.
Metallgesellschaft AG’s subgroup Dynamit Nobel AG broke away from Metallgesellschaft AG in 2004. KKR, an American private equity firm, became the main buyer, integrating parts of Dynamit Nobel AG into Rockwood Holdings Inc. In the process, the US-based Rockwood group took over ownership of the CeramTec AG group. CeramTec continued to grow, acquiring and integrating Emil Müller GmbH (Wilhermsdorf, Germany) into the company as a subsidiary in 2007. A further acquisition followed in 2008; ETEC Gesellschaft für technische Keramik mbH also became a subsidiary and was renamed CeramTec-ETEC GmbH.
In 2013, Rockwood divested several of its companies and the CeramTec group was acquired by the British private equity firm Cinven.
In 2017, CeramTec acquired Morgan UK ElectroCeramics with its two sites in Southampton and Ruabon to complement its existing product portfolio in the field of sensors, capacitors, transducers and piezo ceramics.
In 2017, Cinven sold the CeramTec group of companies to funds advised by private equity investor BC Partners and other co-investors for a purchase price of EUR 2.6 billion.
In spring 2021, the CeramTec Group acquired the Swiss specialist for ceramic dental implants, Dentalpoint AG (today CeramTec Schweiz GmbH). In 2022, the Canada Pension Plan Investment Board (CPPIB) and the BC XI fund advised by BC Partners and co-investors each acquired 50% of the CeramTec Group.
In September 2023, the official ground-breaking ceremony for a new building to expand production capacity in the medical technology sector took place at CeramTec’s Marktredwitz site.
Applications and products
The areas of application for the products, components and solutions cover a range of different markets. A selection of the most important applications:
Medical technology
Orthopaedics: Ceramic components for artificial hip and knee joints
Dental medicine: Bioceramic dental implants
Veterinary ceramic solutions
Medical devices: sensors, ultrasonic applications and structural ceramic components
Dipping moulds for glove production
Automotive & Electronics
Substrates: Ceramic substrates can be used to manufacture numerous key components for electronic applications.
Piezoceramic sensors: These can increase occupant safety and enable intelligent engine control.
Heat sinks: From thermal management in inverters and converters for hybrid and electric vehicles to insulation ceramics for high-voltage PTC heating modules.
Slide, bearing and sealing technology: Improving performance and service life in the automotive industry.
Passive components: coilformers, resistor carriers and fuses for electronic circuits.
Chemical industry
Catalyst carriers: Ceramic carrier materials in heterogeneous catalysis
Grinding granulates, grinding balls and feedstones
Porous products: Resistance in electrochemical processes and electroplating
Tubes & special components
Semiconductor industry
Silicon carbide wafer chucks and other ceramic components with advanced properties
Industrial applications
3D printing with aluminium oxide or silicon carbide: design freedom, time and cost savings
Ceramic tools for the welding process
Pumps, valves and seals
Salt cores: Residue-free cavities in cast components
Sanitary technology: cartridges, sealing and control discs
Silicate ceramics: heating, thermal and insulation technology
Textile industry: Friction discs, thread guides and technical cutting edges
Ultrasonic technology for measurement and sensor applications
Forming technology: wire drawing, tube processing and forming systems
Machining technology
Indexable inserts made of ceramic cutting materials, polycrystalline cubic boron nitride (PcBN) and cermets for metal cutting
Cutting materials, tool systems and tool carrier systems for turning, hard turning, grooving, milling or boring
Main materials
Oxide ceramics
Aluminium oxide
Zirconium oxide
Mixed / Dispersion Ceramics
Aluminium titanate
Silicate ceramic
Piezoceramic
Non-oxide ceramics
Silicon carbide (ROCAR, 3D-printing)
Silicon nitride
Aluminum nitride (Alunit)
SiAIONs
PcBN Polycrystalline cubic boron nitride
Composite materials
Metal Matrix Composite (MMC)
Salt cores
Bonded
Sintered
Core shells
References
External links
Ceramic engineering
Manufacturing companies of Germany | CeramTec | Engineering | 1,480 |
49,862,247 | https://en.wikipedia.org/wiki/International%20Joint%20Conference%20on%20Web%20Intelligence%20and%20Intelligent%20Agent%20Technology | The IEEE/WIC/ACM '''International Joint Conference on Web Intelligence and Intelligent Agent Technology (WI-IAT)''' is a colocated conference focusing on Web intelligence and Intelligent Agent Technology. The conference is a joint undertaking of the Institute of Electrical and Electronics Engineers (IEEE) Computer Society Technical Committee on Intelligent Informatics (TCII), the Web Intelligence Consortium (WIC), SIGAI, and the Memetic Computing Society.
See also
ACM
ACM SIGAI
IEEE
IEEE Computer Society
Memetic Computing Society
References
Web releate
Computer science conferences | International Joint Conference on Web Intelligence and Intelligent Agent Technology | Technology | 122 |
12,424,551 | https://en.wikipedia.org/wiki/Fluorescence%20cross-correlation%20spectroscopy | Fluorescence cross-correlation spectroscopy (FCCS) is a spectroscopic technique that examines the interactions of fluorescent particles of different colours as they randomly diffuse through a microscopic detection volume over time, under steady conditions.
Discovery
Eigen and Rigler first introduced the fluorescence cross-correlation spectroscopy (FCCS) method in 1994. Later, in 1997, Schwille experimentally implemented this method.
Theory
FCCS is an extension of the fluorescence correlation spectroscopy (FCS) method that uses two fluorescent molecules instead of one that emits different colours. The technique measures coincident green and red intensity fluctuations of distinct molecules that correlate if green and red labelled particles move together through a predefined confocal volume. FCCS utilizes two species that are independently labeled with two different fluorescent probes of different colours. These fluorescent probes are excited and detected by two different laser light sources and detectors typically labeled as "green" and "red". By combining FCCS with a confocal microscope, the technique's capabilities are highlighted, as it becomes possible to detect fluorescence molecules in femtoliter volumes within the nanomolar range, with a high signal-to-noise ratio, and at a microsecond time scale.
The normalized cross-correlation function is defined for two fluorescent species, G and R, which are independent green and red channels, respectively:
where differential fluorescent signals at a specific time, and at a delay time, later is correlated with each other. In the absence of spectral bleed-through – when the fluorescence signal from an adjacent channel is visible in the channel being observed – the cross-correlation function is zero for non-interacting particles. In contrast to FCS, the cross-correlation function increases with increasing numbers of interacting particles.
FCCS is mainly used to study bio-molecular interactions both in living cells and in vitro. It allows for measuring simple molecular stoichiometries and binding constants. It is one of the few techniques that can provide information about protein–protein interactions at a specific time and location within a living cell. Unlike fluorescence resonance energy transfer, FCCS does not have a distance limit for interactions making it suitable for probing large complexes. However, FCCS requires active diffusion of the complexes through the microscope focus on a relatively short time scale, typically seconds.
Modeling
The mathematical function used to model cross-correlation curves in FCCS is slightly more complex compared to that used in FCS. One of the primary differences is the effective superimposed observation volume, denoted as in which the G and R channels form a single observation volume:
where and are radial parameters and and are the axial parameters for the G and R channels respectively.
The diffusion time, for a doubly (G and R) fluorescent species is therefore described as follows:
where is the diffusion coefficient of the doubly fluorescent particle.
The cross-correlation curve generated from diffusing doubly labelled fluorescent particles can be modelled in separate channels as follows:
In the ideal case, the cross-correlation function is proportional to the concentration of the doubly labeled fluorescent complex:
with
The cross-correlation amplitude is directly proportional to the concentration of double-labeled (red and green) species.
Experimental method
FCCS measures the coincident green and red intensity fluctuations of distinct molecules that correlate if green and red labeled particles move together through a predefined confocal volume. To perform fluorescence cross-correlation spectroscopy (FCCS), samples of interest are first labeled with fluorescent probes of different colours. The FCCS setup typically includes a confocal microscope, two laser sources, and two detectors. The confocal microscope is used to focus the laser beams and collect the fluorescence signals. The signals from the detectors are then collected and recorded over time. Data analysis involves cross-correlating the signals to determine the degree of correlation between the two fluorescent probes. This information can be used to extract data on the stoichiometry and binding constants of molecular complexes, as well as the timing and location of interactions within living cells.
Applications
Fluorescence cross-correlation spectroscopy (FCCS) has several applications in the field of biophysics and biochemistry. Fluorescence cross-correlation spectroscopy (FCCS) is a powerful technique that enables the investigation of interactions between various types of biomolecules, including proteins, nucleic acids, and lipids.
FCCS is one of the few techniques that can provide information about protein-protein interactions at a specific time and location within a living cell. FCCS can be used to study the dynamics of biomolecules in living cells, including their diffusion rates and localization.
This can provide insights into the function and regulation of cellular processes. Unlike Förster resonance energy transfer, FCCS does not have a distance limit for interactions making it suitable for probing large complexes. However, FCCS requires active diffusion of the complexes through the microscope focus on a relatively short time scale, typically seconds. FCCS allows for measuring simple molecular stoichiometries and binding constants.
See also
Diffusion coefficient
Dynamic light scattering
Fluorescence spectroscopy
References
External links
Fluorescence Cross Correlation (FCCS) (Becker & Hickl GmbH, web page)
Spectroscopy
Physical chemistry
Fluorescence techniques
Biochemistry methods | Fluorescence cross-correlation spectroscopy | Physics,Chemistry,Biology | 1,070 |
68,557,116 | https://en.wikipedia.org/wiki/Tiphaine%20Raguenel | Tiphaine Raguenel ( 13351373) was a Breton noblewoman and astrologer. She was the first wife of Bertrand du Guesclin.
Life
She was the oldest daughter of Robin Raguenel, seigneur de Chatel-Ogier and a veteran of the Combat of the Thirty. Her mother was Jeanne de Dinan, vicomtesse de La Bellière.
In 1363, she married Bertrand du Guesclin in a grand ceremony at the cathedral in Vitré. The marriage was later depicted in a sketch by Paul de Sémant.
Raguenel had a reputation as a learned woman, and as an accomplished astrologer. In 1359, before marrying her husband, she had predicted his victory against Thomas of Canterbury. She is said to have also predicted other results of his battles. While initially treating Raguenel's predictions with contempt, he gave them credit following the French loss in the Battle of Auray, which occurred on a date Raguenel claimed was unfavorable. She and her husband lived in Mont-Saint-Michel. Her former home has been restored and converted into a monument, .
In 2012, a skull attributed to her was found in a reliquary box in an old house in Dinan, and given to the library in Dinan by an anonymous donor.
References
Sources
14th-century Breton women
14th-century Breton people
Astrologers
1373 deaths
1330s births
14th-century astrologers | Tiphaine Raguenel | Astronomy | 306 |
8,870,608 | https://en.wikipedia.org/wiki/Swastika%20Stone | The Swastika Stone is a stone adorned with a design that resembles a swastika, located on the Woodhouse Crag on the northern edge of Ilkley Moor in West Yorkshire, England. The design has a double outline with four curved arms and an attached S-shape, each enclosing a so-called 'cup' mark, the like of which can be found on other stones nearby.
The stone is not verifiably dated; however the academic consensus suggests it to have been carved sometime around the Neolithic or early Bronze Age.
Alternative views have claimed the design is rare in the British Isles, so its close similarity to Camunian rose designs in Lombardy/Italy have led some to theorise that the two are connected. In fact, the troops stationed in Ilkley during Roman occupation were recruited from the Celtic Lingones. This tribe was native to Gaul, but in around 400 BC, some migrated across the Alps to the Adriatic coast. Some believe the Ilkley Lingones were recruited from here rather than from Gaul. It is possible that the Italian Lingones passed through the Valcamonica region at some point, took on the swastika designs they found as part of their tribal symbolism, and carved it on the nearby moor when stationed in Ilkley.
See also
Camunian rose
Fylfot
Germanic pre-Christian use of the swastika
Lauburu
Western use of the swastika in the early 20th century
References
External links
The Swastika Stone
Prehistoric Britain
Archaeological sites in West Yorkshire
Swastika
Petroglyphs
Ilkley
Stones | Swastika Stone | Physics | 320 |
14,087,346 | https://en.wikipedia.org/wiki/Eirpac | EIRPAC is Ireland's packet switched X.25 data network. It replaced Euronet in 1984. Eirpac uses the DNIC 2724. HEAnet was first in operation via X.25 4.8Kb Eirpac connections back in 1985. By 1991 most Universities in Ireland used 64k Eirpac VPN connections. Today Eirpac is owned and operated by Eircom but does not accept new applications for Eirpac: no reference is made on the products-offering on their website They began the process of migrating existing customers using more capable forms of telecommunications back in late April 2004.
In 2001 Eirpac had approximately 5,000 customers dialing in daily via switched virtual circuits although those numbers have been declining rapidly. Eirpac is still an important element for data transfer in Ireland with numerous banks (automatic teller machines), telecoms switches, pager systems and other networks that utilise permanent virtual circuits.
Connecting to Eirpac can be done using a simple AT compatible modem. The dial in number is 1511 + baud rate. So for example to connect at 28,800 bit/s would be ATDT 15112880. The user would then have to authenticate with their Eirpac NUI. The NUI (Network User Identification) consists of a name and password provided by Eir.
Sources
External links
Official website
Computer networking
Internet in Ireland | Eirpac | Technology,Engineering | 290 |
78,142,100 | https://en.wikipedia.org/wiki/Soterenol | Soterenol (), also known as soterenol hydrochloride (; developmental code name MJ-1992) in the case of the hydrochloride salt, is a drug of the phenethylamine family described as an adrenergic, bronchodilator, and antiasthmatic which was never marketed. It is an analogue of salbutamol and acts as a β-adrenergic receptor agonist. The drug was first developed in 1964 and was first described in the literature by 1967.
References
Abandoned drugs
Amines
Antiasthmatic drugs
Beta-adrenergic agonists
Bronchodilators
Phenylethanolamines
Sulfonamides
Sympathomimetics
Isopropylamino compounds | Soterenol | Chemistry | 163 |
6,317,382 | https://en.wikipedia.org/wiki/218%20%28number%29 | 218 (two hundred [and] eighteen) is the natural number following 217 and preceding 219.
In mathematics
Mertens function (218) = 3, a record high.
218 is nontotient and also noncototient.
218 is the number of inequivalent ways to color the 12 edges of a cube using at most 2 colors, where two colorings are equivalent if they differ only by a rotation of the cube.
There are 218 nondegenerate Boolean functions of 3 variables.
The number of surface points on a 73 cube.
See also
The years 218 and 218 BC
References
Integers | 218 (number) | Mathematics | 124 |
53,368,843 | https://en.wikipedia.org/wiki/Al-Ashraf%20Umar%20II | Al-Malik Al-Ashraf (Mumahhid Al-Din) Umar Ibn Yūsuf Ibn Umar Ibn Alī Ibn Rasul (), known as Umar Ibn Yusuf (1296) was the third Rasulid sultan, who ruled as Al-Ashraf Umar II. He was also a mathematician, astronomer and physician.
Biography
Few biographical details about Al‑Malik al‑Ashraf ‘Umar are known. He was born in 1242 in Yemen, and he died in 1296. He excelled in astronomy, agriculture, veterinary science and medicine.
Al‑Ashraf ruled for as the third Rasulid sultan for 21 months from 1295, succeeding after the end of the 46-year rule of his father, . According to the historian David King. In 1266 he commanded a military raid on the Yemenese city of Hajjah. He was made governor of . He was in charge of the highland city of Sanaa, now the capital of Yemen. For a period al‑Ashraf ruled as governor of the flood‑irrigated lands near al‑Mahjam, which was owned by his family.
Family
Al‑Ashraf had six adults sons. Two of his daughters married sons of his younger brother and successor, al-Mu'ayyad Da'ud.
Data from the Encyclopaedia of Islam (1986)
Astronomical work
Al-Ashraf wrote the first description of the use of a magnetic compass for determining the . His works on astronomy contain information on earlier sources.
In a treatise about astrolabes and sundials, al-Ashraf included information on the construction of a compass bowl (). He then uses the compass to determine the north point, the meridian (), and the towards Mecca. This is the first mention of a compass in a medieval Islamic scientific text and its earliest known use as a indicator, although al-Ashraf did not claim to be the first to use it for this purpose.
Al‑Ashraf astronomical treatise includes the names of local Yemeni star names.
Treatise on agriculture
Al-Ashraf's is considered by the historian David King to be crucial for constructing the history of agriculture during the Rasulid era. The work, of which two copies are extant, is the earliest Rasulid treatise about agriculture. The exact title is not known.
The seven chapters of the treatise consider the knowledge of times for planting, transplanting, working the land and improving it; cereal crops (); pulses (), crops grown from seed (); the cultivation of flowering plants (); aromatic plants (); growing vegetables ( and (); and methods of pest control (). The text would have been primarily of use to Yemenese farmers and landowners; there is evidence that Al-Ashraf obtained some of his information from other lands, although no other texts are mentioned.
Notes
References
Sources
(PDF version)
Further reading
1240s births
1296 deaths
13th-century Arab people
13th-century astronomers
Astronomers of the medieval Islamic world
Yemeni astronomers
Monarchs of Yemen
13th-century monarchs in Asia
Rasulid dynasty | Al-Ashraf Umar II | Astronomy | 627 |
41,024,498 | https://en.wikipedia.org/wiki/Dazomet | Dazomet is a common soil fumigant that acts as a herbicide, fungicide, slimicide, and nematicide.
Applications
Dazomet is a chemical used to kill pests that inhibit plant growth through gaseous degradation. Dazomet is used as a soil sterilant on a variety of sites such as golf courses, nurseries, turf sites, and potting soils. Dazomet is used for soil sterilization as an alternative to methyl bromide. Although less effective it is still used to kill pests because of its comparatively lower toxicity. Dazomet is applied to wet soil, which causes dazomet itself to decompose into a gaseous form, which is what actively controls pests. The decomposition of dazomet releases methyl isothiocyanate (MITC) a gas toxic to pests that would prevent or kill plant growth. Dazomet and other methyl isothiocyanate generators are in IRAC group 8F. Dazomet has also been proven to be effective in the prevention of Phellinus noxius, or brown root rot disease.
Synthesis
Dazomet is synthesized from carbon disulfide (CS2) and diluted methylamine (CH3NH2). After stirring for 1-2 hours, an oily substance is formed, which is the intermediate methyldithiocarbamic acid (HS2CNHCH3). Then, formaldehyde (CH2O) is added to the intermediate to form and precipitate out the dazomet.
Form, color, and smell
Dazomet takes the form of colorless crystals. Dazomet is described as having a weakly pungent smell.
Toxicology and safety
Dazomet is irritating to the eyes and its degradation product, MITC, is a dermal sensitizer. Dazomet is very toxic to aquatic organisms, and also acutely toxic to mammals. Exposure to dazomet can occur through several means; interaction with unincorporated granules, inhalation of it decomposition product, MITC, and/or water runoff.
Stability and shelf life
Dazomet is stable at temperatures up to 35°C; it is sensitive to temperature >50°C and to moisture. Dazomet has a shelf life of at least two years when stored below 50°C.
Mass spectrum
The molecular ion peak of dazomet is at 162 m/z. There are two major fragment peaks, one at 89 m/z and one at 42 m/z. The fragment peak at 89 m/z represents the loss of MITC, which is the major, gaseous degrade of dazomet.
Patents
Patent #US5989597
Ambrose Rajamannan was the inventor of the novel process of continuously and instantaneously sterilizing soil using a water-activated fumigant. Dazomet is one water-activated fumigant that could be used. This process ensures 100% activation of the fumigant. Therefore, less fumigant would be needed to ensure that the soil would be completely sterilized.
Patent #CN1543787
See under
References
Herbicides
Insecticides
Nematicides
Dithiocarbamates
Thiadiazines | Dazomet | Chemistry,Biology | 667 |
39,208,494 | https://en.wikipedia.org/wiki/List%20of%20microscopists | This is a list of microscopists by alphabetical order of last name:
Ernst Abbe
Giovanni Battista Amici
Henry Baker
Francisco Balzarotti
Wynne Edwin Baxter
Eric Betzig
Gerd Binnig
David Cockayne
Christian Colliex
Frank Crisp
Gaia Pigino
Christian Gottfried Ehrenberg
Ulrike Endesfelder
Humberto Fernández Morán
Clara Franzini-Armstrong
Franz Josef Giessibl
Johannes Groenland
Pieter Harting
Arthur Hill Hassall
Stefan Hell
Harald Hess
Peter Hirsch
Archibald Howie
Sumio Iijima
Zacharias Janssen
Alfred Kahl
Max Knoll
August Köhler
Ondrej Krivanek
Melike Lakadamyali
Antonie van Leeuwenhoek
Julia Mahamid
Laurence D. Marks
Benjamin Martin
Matthew Fontaine Maury
William E. Moerner
John Howard Mummery
Peter Nellist
Johan Sebastiaan Ploem
John Thomas Quekett
Edwin John Quekett
John Randall
Heinrich Rohrer
Ernst Ruska
Helmut Ruska
Henry Clifton Sorby
Jan Swammerdam
Edward Hutchinson Synge
Ilaria Testa
Knut Urban
Jennifer Waters
M.J. Whelan
Nestor J. Zaluzec
Carl Zeiss
Frits Zernike
See also
Microscopy
Microscopists | List of microscopists | Chemistry | 253 |
9,877,928 | https://en.wikipedia.org/wiki/Joint%20Committee%20on%20Vaccination%20and%20Immunisation | The Joint Committee on Vaccination and Immunisation (JCVI) is an independent expert advisory committee that advises United Kingdom health departments on immunisation, making recommendations concerning vaccination schedules and vaccine safety. It has a statutory role in England and Wales, and health departments in Scotland and Northern Ireland may choose to accept its advice.
History
The committee was established in 1963, having been until then an advisory board for polio immunisation. It gained statutory status as the Standing Advisory Committee on Vaccination and Immunisation, a non-departmental public body advising the Secretary of State for Social Services and the Secretary of State for Wales, under the National Health Service (Standing Advisory Committees) Order 1981.
Since the devolution of government powers to Wales, the JCVI continues to advise Welsh ministers. For England, the Health Protection (Vaccination) Regulations 2009 require the Secretary of State for Health to implement the committee's recommendations regarding national immunisation programmes. The committee has no statutory role in Scotland or Northern Ireland, although the Scottish Parliament takes JCVI advice because it has not formed an alternative body. In 2015 a petition was presented to the Scottish Parliament to depart from JCVI advice because the petitioner felt that the chair of the JCVI was not observing the Nolan Principles. Petitioner had contacted Nicola Sturgeon during her time as Health Minister, and nine years later had decided to petition as a last resort for his proposal to form a body "similar if not the same as Norway's model".
Following the government's review of public bodies that completed in 2012, the JCVI was reconstituted as a departmental expert committee, although its statutory status under the 1981 order continues.
Roles and responsibilities
The JCVI has a responsibility to provide high quality and considered advice and recommendations to the UK Health Ministers. This includes giving advice on recommendations on matters of both a 'routine' nature and also on any specific or special matters that Ministers may request. In formulating any advice and recommendations, the Committee must take into account the need for and impact of vaccines, the quality of vaccines and the strategies to ensure that their greatest benefit to the public health can be obtained from the most appropriate use of vaccines.
JCVI members meet and report as one Committee, usually three times a year. Its recommendations, as accepted by the secretaries of state, are published in "Immunisation against infectious diseases", commonly referred to as The Green Book which provides guidance to clinicians, and also through other routes as necessary (e.g., the Chief Medical Officer letters).
Membership
In June 2018, the JCVI chair was Professor Andrew Pollard of the Oxford Vaccine Group in the Department of Paediatrics at the University of Oxford.
The chair of the COVID-19 subcommittee is Wei Shen Lim, a consultant respiratory physician and honorary professor of medicine at Nottingham University Hospitals NHS Trust.
The current members' names and affiliations are published online although year of appointment is not stated. According to the published code of practice, appointments are normally of three years' duration. In accordance with the Code of Practice issued by the Commissioner for Public Appointments, members cannot serve on the Committee for more than 10 years.
A previous chairman, Andrew Hall, was appointed Knight Bachelor in the 2013 Birthday Honours.
Notable work
Position on MMR (1988 onwards)
The JCVI "expressed concern" about giving triple vaccines to children with a personal or family history of convulsions, but considered it appropriate to proceed with a planned introduction of the MMR vaccine in October 1988, including two products containing Urabe strain. After the start of the mass MMR immunisation programme, additional evidence that the strain was linked with viral meningitis surfaced in a number of countries, and by 1990, many had withdrawn products containing it. In November 1992, it was withdrawn in the UK, following the publication of government-sponsored research which confirmed a high incidence of transitory mild meningitis. Since that time, government agencies have acted to prevent the importation of single vaccines containing this strain.
In late 2000, Andrew Wakefield published what he said were his concerns in the journal Adverse Drug Reactions and Toxicological Reviews, based on his interpretation of early studies of MMR — none of which were actually critical of the vaccine. The article was reviewed in January 2001 by the JCVI, which unequivocally rejected Wakefield's claims, with government agencies publishing a detailed rebuttal. In 2010, Wakefield was struck off by the General Medical Council for fabrication of results and failure to declare a financial interest in the importation of single strain vaccines.
Position on thimerosal (2001)
As is the case in the United States and many other countries, the mercury-based additive thimerosal, previously thought necessary for multi-dose vials of vaccines such as the DPT shot, has largely been phased out. According to the JCVI, it has been shown that the amount of mercury in the blood of children receiving thimerosal-containing vaccines is well below levels that may be "associated with any toxic effects." Reports reviewed by the JCVI contended that mercury exposure in the UK immunisation programme was low. However, in 2001, JCVI endorsed recommendations to remove the preservative, stating: "even though there is no evidence of toxicity, as a precautionary measure, thiomersal should be phased out over time...".
COVID-19 vaccines (2020–2024)
During the COVID-19 pandemic, in autumn 2020 the committee gave advice to the recently formed Vaccine Taskforce on the groups of people that should be prioritised for vaccination, giving regard to health inequalities. Their advice was refined in December of that year.
On 6 April 2021, Maggie Wearmouth of the JCVI said "in a personal capacity" that the vaccine roll-out should be slowed "in younger people" to maintain public trust and confidence, after the committee had discussed concerns over a possible link between the Oxford–AstraZeneca vaccine and a rare type of blood clot.
The next day in a press conference, the JCVI stated that it "believes healthy young people aged 18 to 29 should be offered the Pfizer-BioNTech or Moderna vaccines instead of the AstraZeneca jab" because of the risk of CVST blood clots. The press conference was offered by the "chair of the JCVI" (sic) Wei Shen, who said "every country has to take their own decision based on their own population, the scale of the pandemic, the values of its people and the quantity of vaccines." The JCVI had judged safety evidence from the MHRA and Public Health England in coming to its decision. Adam Finn, a member of the JCVI, said on BBC Breakfast that "it was possible doses of the Moderna jab could be reserved for young people... We are seeing another vaccine coming in (Moderna), and further vaccines are approaching licensure, and I know that the UK has made contracts for quite a wide range of different vaccines. As time goes forward we will have much more flexibility about who can be offered what."
The updated advice from the JCVI was published on 13 April 2021, stating "it is preferable for adults aged 18 to 29 years without underlying health conditions that put them at higher risk of severe COVID-19 disease, to be offered an alternative to the AstraZeneca COVID-19 vaccine, if available". On 7 May the applicable age range was extended to 18–39.
In February 2022, JCVI recommended a further booster dose for the most vulnerable people, to be given around six months after their previous dose. Those eligible were in three categories: aged 75 and over, residents in care homes for older adults, and immunosuppressed people aged 12 and over.
The initial JCVI recommendation for a booster programme in autumn 2022 (published as interim advice in May) included everyone aged 65 and over, selected workers and care home residents, and people in clinical risk groups aged 16 and over. In July, their final recommendations for the autumn programme were widened to include people aged 50 and over, residents and staff in care homes for older adults, front-line health and social care workers, unpaid carers, people aged 5 to 49 in clinical risk groups, and household contacts aged 5 to 49 of those who are immunosuppressed. Refinements to the advice in August included the addition of the first approved bivalent vaccine from Moderna, although the committee found it would give only a marginally higher immune response, and stated that timeliness was more important than the type of vaccine. A second bivalent vaccine from Pfizer-BioNTech was later added to the recommendations for the Autumn 2022 programme.
For the 2023 spring programme, JCVI recommended booster doses for people aged 75 and over, all residents in care homes for older adults, and everyone aged 5 and over who is immunosuppressed. The recommendation for the 2023 autumn booster set the general age cut-off at 65, and again included care home residents and front-line health and social care workers. Lower age limits were adjusted: six months for clinical risk groups, 12 for household contacts of people with immunosuppression, and 16 for carers and care home staff.
For spring 2024, doses were again recommended for those aged 75 and over, residents in care homes for older adults, and immunosuppressed people aged 6 months and over. Vaccination in autumn 2024 was recommended (as in 2023) for adults over 65, residents in a care home for older adults, and those aged 6 months and over in a clinical risk group; but not for health and social care workers, staff in care homes for older adults, unpaid carers and household contacts of people with immunosuppression. In August 2024, the UK government decided to continue to offer vaccination to frontline health and social care staff, as well as staff in care homes for older people, in the autumn 2024 programme.
The JCVI recommendation for spring 2025 was the same as for spring 2024.
For young people
In late July 2021, the JCVI advised that all 16- and 17-year-olds should be given a first dose of the Pfizer-BioNTech vaccine, with advice on a second dose expected to be given in the future; this advice was published by the government on 4 August. Two doses were already available for certain at-risk people aged 16 and over. Those aged 12 to 15 with specific underlying health conditions were already eligible for two doses of the same vaccine, and the new advice extended this to children who are household contacts of immunosuppressed people. In December 2021, this recommendation was expanded to certain at-risk children aged 5–11, and two doses were recommended for all children aged 12–17. In February 2022, the JCVI advised that two doses of Pfizer-BioNTech vaccine should be offered on a "non-urgent" basis to parents of all 5–11-year-olds.
Around July 2021, some medical commentators raised concerns that the committee had not taken into account all risks to children, particularly long COVID, and pointed out that other countries – including the United States – were already vaccinating everyone aged 12 and over.
See also
Medicines and Healthcare Products Regulatory Agency (MHRA)
National Immunization Technical Advisory Group (NITAG), a global concept of immunisation advisory committee
Advisory Committee on Immunization Practices (NITAG in the United States)
National Advisory Committee on Immunization (NITAG in Canada)
National Immunisation Advisory Committee (NITAG in Ireland)
Standing Committee on Vaccination (NITAG in Germany)
New and Emerging Respiratory Virus Threats Advisory Group (in the United Kingdom)
References
External links
Guardian.co.uk – 'Influenza vaccine to be encouraged for women in late pregnancy', Sarah Boseley, The Guardian (25 October 2006)
Telegraph.co.uk – 'Early fears about MMR in secret papers', Mark Watts, Daily Telegraph (5 March 2007)
Government agencies established in 1963
Medical and health organisations based in the United Kingdom
Vaccination-related organizations
Joint committees | Joint Committee on Vaccination and Immunisation | Biology | 2,518 |
29,454,405 | https://en.wikipedia.org/wiki/Phospholipid%20acyltransferase | This family contains acyltransferases involved in phospholipid biosynthesis and proteins of unknown function. This family also includes tafazzin, the Barth syndrome gene.
Subfamilies
1-acyl-sn-glycerol-3-phosphate acyltransferase
Human proteins containing this domain
AGPAT1; AGPAT2; AGPAT3; AGPAT4; AGPAT5; AGPAT6; AGPAT7; AYTL1;
AYTL2; GNPAT; GPAM; GPAT3; LYCAT; TAZ; TMEM68;
References
Protein domains
Protein families | Phospholipid acyltransferase | Biology | 148 |
5,011,619 | https://en.wikipedia.org/wiki/Oracle%20Labs | Oracle Labs (formerly Sun Microsystems Laboratories, or Sun Labs) is a research and development branch of Oracle Corporation. The labs were created when Oracle acquired Sun Microsystems. Sun Labs was established in 1990 by Ivan Sutherland and Robert Sproull. The initial locations were in Menlo Park, California and Burlington, Massachusetts, United States.
Oracle Labs has locations in Redwood Shores, California; Burlington, Massachusetts; Cambridge, UK; Brisbane, Australia; Linz, Austria; Zürich, Switzerland; and Casablanca, Morocco.
Sun
Sun Labs worked in areas such as asynchronous circuits, optical communications, new web technologies, Java technologies, and computer networks. James G. Mitchell directed the labs starting in 2000.
When asked in 2007 why Sun continued to put resources into research as the market turned to commodity pricing, chief executive Jonathan I. Schwartz said, "You need to spend enormous amounts of money to differentiate."
Oracle
In 2010 after Sun was purchased by Oracle Corporation, it became Oracle Labs.
Sproull was director.
He was appointed in June 2006.
References
External links
Organizations established in 1990
Sun Microsystems
Research organizations in the United States
Information technology organizations
Information technology places
Buildings and structures in San Mateo County, California
Burlington, Massachusetts
Menlo Park, California | Oracle Labs | Technology | 254 |
56,789,579 | https://en.wikipedia.org/wiki/L%27Astronomie | LAstronomie () is a monthly astronomy magazine published by the Société astronomique de France (SAF). Sylvain Bouley, the president of SAF, is the publication director and astronomer Fabrice Mottez is the editor-in-chief.
History
The magazine was established by Camille Flammarion and the first issue, dated 1882, was published on January 1, 1883. After SAF was founded in 1887, a second journal was created, called the Bulletin mensuel de la Société Astronomique de France. The two publications existed in parallel up to 1894. In the December 1894 issue, Flammarion announced in an editorial that LAstronomie would cease to exist. From January 1895 to December 1910, only the Bulletin de la Société Astronomique de France was published. Starting from 1912, the Bulletin was renamed LAstronomie, while preserving the volume numbering of the Bulletin.
Distribution
The magazine is available by subscription both in France and internationally in hard copy and digital formats. It is also sold in newspaper kiosks and magazine stands in France, Belgium, Luxembourg, Switzerland and Morocco.
Electronic versions of L'Astronomie and Bulletin de la Société astronomique de France from 1882 to 1953 (except 1949) are available from the Bibliothèque nationale de France's Gallica website.
References
External links
L'Astronomie official website
L'Astronomie, revue mensuelle d'astronomie populaire (1882-1894) on Gallica
Bulletin de la Société astronomique de France (1887–1910) on Gallica
L'Astronomie : revue mensuelle d'astronomie, de météorologie et de physique du globe et bulletin de la Société astronomique de France (1911-1953, except 1949) on Gallica
Astrophysics Data System (ADS) provides scanned articles of Bulletin de la Société astronomique de France and L'Astronomie (1882–1988), and abstracts or citations (1989-present) using publication code LAstr.
1883 establishments in France
Amateur astronomy
Astronomy magazines
French-language magazines
Monthly magazines published in France
Magazines established in 1883
Magazines published in Paris | L'Astronomie | Astronomy | 458 |
11,322,755 | https://en.wikipedia.org/wiki/Corticium%20penicillatum | Corticium penicillatum is a species of fungus in the class Agaricomycetes. It is a corticioid fungus and a plant pathogen, the causal agent of coconut thread blight, a leaf disease of coconut palms. The species was originally described from Papua New Guinea in 1925 and has since been reported from Vanuatu, Fiji, and the Solomon Islands. Corticium penicillatum has never been redescribed or reviewed and is unlikely to be a species of Corticium in the modern sense.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Coconut palm diseases
Taxa named by Thomas Petch
Fungi of Oceania
Fungi of New Guinea
Fungi described in 1925
Fungi without expected TNC conservation status
Fungus species | Corticium penicillatum | Biology | 161 |
1,601,887 | https://en.wikipedia.org/wiki/Mount%20Wachusett | Mount Wachusett is a mountain in Massachusetts. It straddles towns of Princeton and Westminster, in Worcester County. It is the highest point in Massachusetts east of the Connecticut River. The mountain is named after a Native American term meaning "near the mountain" or "mountain place". The mountain is a popular hiking and skiing destination (see 'Wachusett Mountain Ski Area"). An automobile road, open spring to fall, ascends to the summit. Views from the top of Mount Wachusett include Mount Monadnock to the north, Mount Greylock to the west, southern Vermont to the northwest, and Boston to the east. The mountain is traversed by the Midstate Trail. It is also home to the Wachusett Mountain State Reservation.
A band of old growth forest along rock ledges below the summit supports trees from 150 to 370 years old. Covering , it is the largest known old growth forest east of the Connecticut River in Massachusetts.
Geography
Mount Wachusett is a (formerly) glaciated monadnock: a single mountain on a relatively flat landscape. Glacial activity that shaped the mountain can be seen at Balance Rock on the northeast side of the mountain: two large boulders were stacked one on top of each other by moving glaciers thousands of years ago.
Mount Wachusett is bordered to the south by Little Wachusett Mountain and Brown Hill, to the north by Church Rock, to the east by Pine Hill, and to the northeast by the Crow Hills. The nearest mountain of comparable size is Mount Watatic, 1,832 feet (558 m), to the north on the New Hampshire border in Ashburnham, Massachusetts.
The west side of Mount Wachusett drains into the east branch of the Ware River, thence into the Chicopee River, the Connecticut River, and Long Island Sound. The south side drains into the Quinapoxet River, the Nashua River, thence the Merrimack River and the Atlantic Ocean. The east side drains into the Stillwater River, thence the Nashua River. The north side drains into the Nashua River through a series of small reservoirs.
Ski area and recreation
Mount Wachusett is home to a 25-trail ski area serviced by 3 high-speed quads, 1 fixed-grip triple and 3 carpet lifts. It features approximately of vertical, a base lodge, 100% snowmaking and night skiing on 18 trails. The mountain also maintains a terrain park and a jump called the Main Event. Due to its location, it is a popular skiing destination for residents of nearby Worcester and Boston. The ski area is located within the boundaries of the Wachusett Mountain State Reservation on a lease parcel on the northern slopes of the mountain.
There is an annual 6.2 mile (10 km) road race each May sponsored by the Central Mass Striders.
Stands of old-growth hardwood forest on Mount Wachusett became the object of a 2003 court ruling in favor of the Commonwealth of Massachusetts in joint contract with the ski area regarding plans for a ski slope expansion into an environmental buffer zone around the old growth stand. The old growth forest contains trees over 350 years old; the buffer zone contained mature trees about half that age. The Sierra Club and other conservation organizations criticized the ruling and two members of Earth First! staged a sit-in protest by climbing into the crowns of several of the trees in the area slated to be clear cut. As of 2007 wording on the website of the Wachusett Mountain Ski Area included strong language prohibiting skiers and snow boarders from entering the old growth area: "Anyone found entering old growth areas will have their lift ticket revoked. Subsequent offenses will be subject to fines."
History
Before European colonialism, Wachusett was the home of the Nipmuc tribe. The tribe has been confined to a four-and-a-half acre reservation outside Grafton, Massachusetts, which began as a praying town in 1654. The general feeling towards the ski resort among Nipmucs is that it is an injustice. Some hope to someday use the mountain as a proper Nipmuc cultural center. During King Philip's War in 1676, Native Americans brought their captive, Mary Rowlandson, to Wachusett to release her to the colonists at Redemption Rock.
See also
The name Wachusett has been adopted for the names of institutions, businesses, structures, geographic features, and other miscellaneous uses:
Wachusett Reservoir
Wachusett Mountain State Reservation
Wachusett Brewing Company
Wachusett (MBTA station)
Mount Wachusett Community College
Wachusett Regional High School
USS Wachusett
Wachusett Road in the Town of Woodway, Washington
Wachusett Potato Chips Company
It is also the title of Henry David Thoreau's A Walk to Wachusett, which describes the transcendentalist author's experiences during his four-day walk from Concord to the mountain and back.
References
External links
Massachusetts DCR Wachusett Mountain State Reservation page
Wachusett Brewing Company
The view from Mount Wachusett
Princeton history of the Mountain
People of the Wachusett: Greater New England in History and Memory, 1630-1860
Wachusett, Mount
Mountains of Worcester County, Massachusetts
Princeton, Massachusetts
Westminster, Massachusetts
Old-growth forests | Mount Wachusett | Biology | 1,068 |
8,852,523 | https://en.wikipedia.org/wiki/List%20of%20virtual%20printer%20software | The following is a list of Wikipedia articles relating to virtual printer software:
Free software
The following are distributed under free software licences:
CC PDF Converter (discontinued) – A Ghostscript-based virtual printer.
clawPDF – An open source virtual PDF/OCR/Image Printer with network sharing and ARM64 support .
cups-pdf – An open source Ghostscript-based virtual printer that can be shared with Windows users over the LAN. CUPS
Ghostscript – A command-line library for creation of PostScript and PDF files.
RedMon – Redirects a special printer port to the standard input of another program
Freeware
The following are proprietary software but free of charge:
Virtual PDF printers
Virtual PDF printers for Microsoft Windows:
Bullzip PDF Printer – there is a free version
CutePDF
DoPDF – this is a simplified version of NovaPDF
PDFCreator – a Ghostscript-based virtual printer for Microsoft Windows, with user interface for advanced options (security settings, combining multiple documents, etc.).
PrimoPDF
Print To PDF - ships with Windows 10 and 11
PDF24 Creator – a free virtual PDF printer for Microsoft Windows, with user interface and additional tools like merging, splitting, compressing and assembling PDF files.
Commercial
Adobe Acrobat – Adobe System's commercial PDF authoring suite includes Adobe Distiller, a virtual printer for converting documents to PDF files. Adobe Distiller is not included with the free-to-use Adobe Reader product.
Virtual printers
Virtual printers for Microsoft Windows:
Microsoft Office Document Image Writer – Included in Microsoft Office Professional allowing documents to be saved in TIFF or Microsoft Document Imaging Format. MODI is only supported in 32 bit Windows' versions.
Universal Document Converter – Creating PDF, JPEG, TIFF, PNG, GIF, PCX, DCX and BMP files. Free version adds watermark.
Notes
1.This software has risk of installing potentially unwanted programs. For more information, refer to its main article.
Virtual printer software
Computer printers | List of virtual printer software | Technology | 413 |
50,724,296 | https://en.wikipedia.org/wiki/AN/ALQ-218 | The AN/ALQ-218 is an American airborne electronic warfare radar warning receiver (RWR) system, found on Grumman/Northrop Grumman EA-6B Prowler and Boeing EA-18G Growler aircraft.
Description
The AN/ALQ-218 is an airborne passive Radar warning receiver / electronic warfare support measures / electronic signals intelligence (RWR/ESM/ELINT) sensor system designed for airborne situational awareness and signal intelligence gathering. The AN/ALQ-218 detects, identifies, locates and analyzes sources of radio frequency emission. The current version AN/ALQ-218(V)2 is manufactured by Northrop Grumman.
The Next Generation Jammer Mid-Band is able to integrate with AN/ALQ-218.
Platforms
The ALQ-218 is mainly featured aboard the U.S. Navy's Boeing EA-18G Growler aircraft, which has replaced the EA-6B Prowler in the U.S. Navy. The ALQ-218 was previously on the Grumman EA-6B Prowler, which the Improved Capability III ALQ-218 was modified and integrated into the EA-18G's Airborne Electronic Attack (AEA) system. Avionics from the EA-6B were modified to fit into the gun bay and wing tip pods of the Growler.
The EA-18G may carry an additional five jamming pods on under wing pylons. The system is being considered for modification to serve on unmanned aerial vehicles. The Growler is part of the same family of aircraft as the F/A-18E/F Super Hornet.
References
See Also
List of military electronics of the United States
External links
Electronic warfare equipment
Military electronics of the United States
Radar warning receivers | AN/ALQ-218 | Technology | 369 |
142,008 | https://en.wikipedia.org/wiki/Moscow%20theater%20hostage%20crisis | The Moscow theater hostage crisis (also known as the 2002 Nord-Ost siege) was the seizure of the crowded Dubrovka Theater in Moscow by Chechen terrorists on 23 October 2002, resulting in the taking of 912 hostages. The attackers, led by Movsar Barayev, claimed allegiance to the Islamist separatist movement in Chechnya. They demanded the withdrawal of Russian forces from Chechnya and an end to the Second Chechen War. The crisis was resolved when Russian security services released sleeping gas into the building, and subsequently stormed it, killing all 40 hostage takers. 132 hostages died, largely due to the effects of the gas.
Due to the layout of the theater, special forces would have had to fight through of corridor and advance up a well-defended staircase before they could reach the hall in which the hostages were held. The attackers had numerous explosives, with the most powerful in the center of the auditorium. Spetsnaz operators from Federal Security Service (FSB) Alpha and Vympel, supported by a Russian Ministry of Internal Affairs (MVD) SOBR unit, pumped a chemical agent into the building's ventilation system and began the rescue operation.
The identity of the gas was not disclosed at the time, although it was believed to have been a fentanyl derivative. A study published in 2012 concluded that it had been a mixture of carfentanil and remifentanil. The same study pointed out that in a 2011 case at the European Court of Human Rights, the Russian government stated that the aerosol used was a mixture of a fentanyl derivative and a chemical compound with a narcotic action.
Initial siege
The hostages were seized on 23 October at the House of Culture of State Ball-Bearing Plant Number 1 in the Dubrovka area of Moscow about four kilometers south-east of the Moscow Kremlin. During Act II of a sold-out performance of Nord-Ost a little after 9:00 PM, 40–50 heavily armed masked men and women drove in a bus to the theater and entered the main hall firing assault rifles in the air.
The black-and-camouflage-clad attackers took approximately 850–900 people hostage, including members of the audience and performers, among them an MVD general. The reaction of spectators inside the theater to the news that the theater was under terrorist attack was not uniform: some people remained calm, some reacted hysterically, and others fainted. Some performers who had been resting backstage escaped through an open window and called the police; in all, some 90 people managed to flee the building or hide.
The terrorist leader told the hostages that the attackers (who identified themselves as a suicide squad from "the 29th Division") had no grudge against foreign nationals (about 75 in number from 14 countries, including Australia, Georgia, Germany, the Netherlands, Ukraine, the United Kingdom and the United States) and promised to release anyone who showed a foreign passport.
Demands
The gunmen were led by Movsar Barayev, nephew of slain Chechen rebel militia commander Arbi Barayev, and threatened to kill the hostages unless Russian forces were immediately and unconditionally withdrawn from Chechnya. They said the deadline was one week, after which they would start killing the hostages.
A videotaped statement was acquired by the media in which the gunmen declared their willingness to die for their cause. The statement contained the following text:
According to the Kremlin's aide Sergei Yastrzhembsky, "When they were told that the withdrawal of troops was unrealistic within the short period, that it was a very long process, the terrorists put forward the demand to withdraw Russian troops from anywhere in the Republic of Chechnya without specifying which area it was." The hostage-takers demanded termination of the use of artillery and air forces in Chechnya starting the next day (Russian forces ceased using heavy weapons until 28 September), a halt to the notorious zachistka ("mopping-up") operations, and that President of Russia Vladimir Putin should publicly declare that he was striving to stop the war in Chechnya. By the time of the hostage-taking, the conflict in the embattled republic was killing an average of three federal troops daily.
Cell phone conversations between the hostages trapped in the building and their family members revealed that the hostage-takers had grenades, mines and improvised explosive devices strapped to their bodies, and had deployed more explosives throughout the theater. The militants used Arabic names among themselves, and the female terrorists wore Arab-style niqab clothes which are highly unusual in the North Caucasus region.
Mufti Akhmad-Khadzhi Shamayev, official leader of Chechnya's Muslims, said he had no information about who the attackers were and condemned attacks on civilians. The pro-Moscow Islamic leader of Chechnya also condemned the attack.
All hostages were kept in the auditorium and the orchestra pit was used as a lavatory. The situation in the hall was nervous and it frequently changed depending on the mood of the hostage-takers, who were following reports in the mass media. Any kind of misinformation caused hopelessness among the hostages and new aggression among their captors, who would threaten to shoot hostages and blow up the building, but no major incidents took place during the siege. The gunmen let members of the audience make phone calls. One hostage used her mobile phone to plead with authorities not to storm the auditorium, as truckloads of police and soldiers with armored vehicles surrounded the building.
Hostage-taking
Day one23 October
The attackers released 150 to 200 people, including children, pregnant women, Muslims, some foreign-born theater-goers and people requiring medical treatment in the early hours after they invaded. Two women managed to escape (one of them was injured while escaping). The terrorists said they were ready to kill ten hostages for any of their number killed if the security forces intervened.
Olga Romanova
At 1:30 AM, Olga Romanova, a 26-year-old civilian acting on her own, entered the theater, crossing the police cordon by herself. She entered the theater and began urging the hostages to stand up to their captors. There was considerable confusion in the auditorium. The terrorists believed she was a Federal Security Service (FSB) agent and she was shot and killed seconds later. Romanova's body was later removed from the building by a Russian medical team, incorrectly reported by the Moscow police as the body of the first hostage who was killed while trying to escape. Romanova was described as "strong-willed", and lived near the theater. It is unknown how she crossed the police lines undetected.
Day two24 October
The Russian government offered the hostage-takers the opportunity to leave for any country other than Russia or Chechnya if they released all hostages unharmed. The hostages made an appeal, possibly under orders or duress, for Putin to cease hostilities in Chechnya and asked him to refrain from assaulting the building. Because of the crisis, Putin canceled an overseas trip that would have included meetings with then-U.S. President George W. Bush and other world leaders.
The hostage-takers demanded to talk with Joseph Kobzon, a member of parliament and singer, and with International Red Cross representatives. Kobzon (accompanied by three people, including a man waving some white fabric like a flag), entered the building about 1:20 PM. Shortly thereafter, a man in his sixties, appearing feeble and distraught, left the theater. The Interfax news agency identified him as a British citizen, but did not provide details. A woman and three children, believed to be Russians, were let out a few minutes later.
Other well-known public and political figures such as Aslambek Aslakhanov, Irina Khakamada, Ruslan Khasbulatov, Boris Nemtsov and Grigory Yavlinsky took part in negotiations with the hostage-takers. Ex-President of the Soviet Union Mikhail Gorbachev also announced his willingness to act as an intermediary in the course of negotiations. Militants also demanded that representatives of the International Red Cross and Médecins Sans Frontières (Doctors Without Borders) come to the theater to lead negotiations. FSB Colonel Konstantin Vasilyev attempted to enter the patio of the theater, but was shot at while approaching the building and forced to retreat.
According to the FSB, thirty nine hostages were set free by the terrorists on 24 October 2002, but they repeated via one of the hostages an earlier threat to start shooting their captives if Russia failed to take their demands seriously. Negotiations on the release of non-Russian nationals were conducted by various embassies and the Chechens promised to release all foreign hostages. The kidnappers claimed they were ready to release 50 Russian hostages if Akhmad Kadyrov, head of Chechnya's pro-Moscow administration, would come to the theater, but Kadyrov did not respond, and the release did not take place.
A hot water pipe burst overnight and was flooding the ground floor. The hostage-takers called the flooding a "provocation" and an FSB spokesman said no agreement had been reached on having the pipe repaired. It later turned out that the sewer system was used by the Russian special forces for listening purposes.
Day three25 October
During the third day, the following people took part in negotiations with the militants: journalists Anna Politkovskaya, Sergei Govorukhin and Mark Franchetti as well as public figures Yevgeny Primakov, Ruslan Aushev and again, Aslambek Aslakhanov. The terrorists demanded negotiations with an official representative of Vladimir Putin. Relatives of the hostages staged anti-war demonstrations outside the theater and in central Moscow.
The hostage-takers agreed to release seventy-five foreign citizens in the presence of diplomatic representatives of their states. 15 Russian citizens were released, including eight children (aged 7 to 13). After a meeting with Putin, the FSB head Nikolai Patrushev offered to spare the lives of the Chechens if they released the remaining hostages unharmed.
A group of Russian doctors including Dr. Leonid Roshal, head of the Medical Center for Catastrophes, entered the theater to bring medicine for the hostages and said the terrorists were not beating or threatening their captives. He said most of the hostages were calm and that only "two or three" of the hostages were hysterical. Some hot food, warm clothes, and medicine had also been taken in by the Red Cross.
NTV channel journalists recorded an interview with Movsar Barayev, in which he sent a message to the Russian government:
We have nothing to lose. We have already covered 2,000 kilometers by coming here. There is no way back... We have come to die. Our motto is freedom and paradise. We already have freedom as we've come to Moscow. Now we want to be in paradise.
He also said the group had come to Moscow not to kill the hostages or to fight with Russia's elite troops, as they had had enough fighting in Chechnya over the years: "We came here with a specific aimto put an end to the war and that is it."
At 9:55 PM, four hostages (citizens of Azerbaijan) were released, bringing the total number of hostages that were set free on this day to 19.
Gennady Vlakh
After dusk, a man identified as Gennady Vlakh ran across the square and gained entry to the theater. He said that his son was among the hostages, but his son did not seem to be present and the man was led away and shot by the Chechens.
There is considerable confusion surrounding this incident, and Vlakh's body was cremated before it was identified.
Denis Gribkov
Around midnight, a gunfire incident took place as Denis Gribkov, a 30-year-old male hostage, ran over the backs of theater seats toward the female insurgents who were sitting next to a large improvised explosive device. A male Chechen shot at him and missed, but stray bullets hit and severely wounded Tamara Starkova and fatally wounded Pavel Zakharov, who were evacuated from the building soon after. Gribkov was removed from the auditorium and later found dead from gunshot wounds.
Day fourMorning of 26 October
During the night, Akhmed Zakayev, a Chechen envoy and associate of the separatist President Aslan Maskhadov, appealed to the extremists and asked them to "refrain from rash steps". The Chechens told the BBC that a special representative of President Putin planned to come to the theater for talks the next day. Two members of the Spetsnaz Alpha Group moving around in the no-man's land were seriously wounded by a grenade fired from the building by the terrorists, which was blamed by the Moscow police chief Vladimir Pronin on the media news leak.
According to an officer in the Russian special forces cited by The Guardian, the leak was controlled: "We leaked the information that the storming would take place at three in the morning. The Chechen fighters were on their guard. They began shooting, but there was no raid. Then there was the natural reactiona relaxation. And at 5 a.m. we stormed the place."
Special forces raid
Early Saturday morning, 26 October, forces from Russia's Spetsnaz (Special Forces, literally "special purpose") from the FSB (Alpha Group and Vympel), with the assistance of the Russian Ministry of Internal Affairs (MVD) SOBR unit, surrounded and stormed the theater; all were heavily armed and masked. Deputy Interior Minister Vladimir Vasilyev stated that the raid was prompted by a panic among the captives due to the execution of two female hostages. The raid was planned shortly after the hostages were initially seized and the shooting cited as a proximate cause had occurred about three hours before the operation began.
Chemical attack
Early in the morning before dawn, at around 5:00a.m. Moscow time, the searchlights that had been illuminating the main entrance to the theater went out.
Inside, although many hostages at first took the gas (aerosol) to be smoke from a fire, it soon became apparent to gunmen and hostages alike that a mysterious gas had been pumped into the building. Different reports said it came either through the specially created hole in the wall, that it was pumped through the theater's ventilation system, or that it emerged from beneath the stage. The security services pumped an aerosol anaesthetic, later stated by Russian Health Minister Yuri Shevchenko to be based on fentanyl, into the theater through the air conditioning system. The discovery caused panic in the auditorium. Hostage Anna Andrianova, a correspondent for Moskovskaya Pravda, called Echo of Moscow radio studio and conducted a live broadcast with hostages who started feeling the effects of the gas used by the government forces and begged them to desist.
Assault
The Chechens, some of whom were equipped with gas masks, responded by firing blindly at the Russian positions outside. After thirty minutes, when the gas had taken effect, a physical assault on the building commenced. The combined forces entered through numerous building openings, including the roof, the basement, and finally the front door.
When the shooting began, the terrorists told their hostages to lean forward in the theater seats and cover their heads behind the seats. Hostages reported that some people in the audience fell asleep, and some of the gunmen put on respirators. As the terrorists and hostages alike began to fall unconscious, several of the female terrorists made a dash for the balcony but passed out before they reached the stairs. They were later found shot dead. Two of the Spetsnaz Alpha Group were also overcome by the gas.
After nearly one and a half hours of sporadic gun battles, the Russian special forces blew open the doors to the main hall and poured into the auditorium. In a fierce firefight, the federals killed most of the hostage-takers, both those still awake and those who had succumbed to the gas.
According to the Russian government, fighting between the troops and the still-conscious Chechen fighters continued in other parts of the building for another 30 minutes to one hour. Initial reports stated that three terrorists were captured alive (the BBC reported that a "handful of surviving fighters were led away in handcuffs") and two of them managed to escape. Later, the government claimed that all hostage-takers had been killed in the storming.
Alpha team troops said that "this is our first successful operation [in] years". Moskovskij Komsomolets cited a Russian special forces operative saying that "if it were a usual storming, we'd have had 150 casualties among our men, added to the hostages."
Evacuation
At 7:00 a.m., rescuers began carrying the bodies of hostages out of the building. Bodies were laid in rows in the foyer and on the pavement at the main entrance to the TC, unprotected from falling rain and snow. None of the bodies witnessed by The Guardian correspondent Nick Paton Walsh had bullet wounds or showed signs of bleeding, but "their faces were waxy, white and drawn, their eyes open and blank." Shortly, the entire space was filled with bodies of the dead and those unconscious from the gas but still alive.
Ambulances were standing by and ordinary city buses were brought in. Medical workers were expecting to treat victims of explosions and gunfire but not a secret chemical agent. If the drug used was indeed a fentanyl derivative or other μ-opioid receptor agonist, an opioid receptor antagonist drug like naloxone would have counteracted the chemical agent's effects, but would have had to be administered by rescue workers immediately upon arriving. Some reports said the drug was used to save some hostages.
The bodies of dead hostages were put in two buses which were parked at the TC. Initial reports said nothing about casualties among the hostages. The crisis HQ representatives went to the college hall, where relatives of the hostages had been waiting, and told them that allegedly there were no fatalities among the hostages. The first official report of fatalities among the hostages came at about 9:00 a.m. Despite the death of five children which had been already reported by medical personnel, the official statement claimed there were no children among the dead.
At 1:00 p.m., Vasilyev announced at a press conference a "definitive" death toll of 67 hostages, who he said were killed by Chechens, but again said no children nor foreigners were among those killed. Armed guards were posted at the hospitals where victims were taken and doctors were ordered not to release any of the theater patients in case militants had concealed themselves among the hostages.
The hostages' family members panicked as the government refused to release any information about which hospitals their loved ones had been taken to, or even whether their relatives were among the dead. The official number of the dead rose to 90, including 25 children, while it was still claimed that the final attack was provoked by the terrorists executing their captives. Later the same day, the official death toll among hostages had risen to at least 118 and the officials had not specified exactly what killed them. By 28 October, of the 646 former hostages who remained hospitalized, 150 were still in intensive care and 45 were in critical condition.
Seventy-three hostages (including six minors) were rendered no medical aid. There were several Chechens among the hostages and it may be that some of them were not treated because of their Chechen names. Money and other valuables belonging to the victims vanished; official reports stated that the valuables were stolen by an FSB officer who was later killed in a car crash. The Russian authorities initially maintained that none of the deaths among the hostages occurred through poisoning. They spoke of health problems that were exacerbated by the three-day ordeal with very little food or water, or indeed, medical attention.
Casualties
The number of estimated casualties varies widely because many hostages remained unaccounted for and were not included in the official list (see below). Some estimates have put the civilian death toll at more than 200 with 204 names on one list, or even 300, including people who died during the year after the siege from complications from the poison gas. Some former hostages and relatives of the victims claim that the death toll from the chemical agent is being kept secret. According to official numbers, 40 terrorists and about 130 hostages died during the raid or in the following days.
Doctor Andrei Seltsovsky, Moscow's health committee chairman, announced that all but one of the hostages killed in the raid had died from the effects of the unknown gas rather than from gunshot wounds. The cause of death listed for all hostages was declared to be "terrorism," claiming they died from heart attacks or other physical ailments. Among the fatalities, 17 were Nord-Ost cast members, including two child actors. Of the foreign nationals, three were from Ukraine, and the others were citizens of Austria, Armenia, Belarus, Kazakhstan, the Netherlands and the United States. About 700 surviving hostages were poisoned by the gas, and some of them received injuries leading to second- and third-degree disabilities (indicating medium- and light-severity debilitation in the Russian disability classification system). Several Russian special forces operatives were also poisoned by the gas during the operation. According to court testimony from Prof. A. Vorobiev, Director of the Russian Academic Bacteriology Center, most, if not all, of the deaths were caused by suffocation when hostages collapsed on chairs with heads falling back or were transported and left lying on their backs by rescue workers; in such a position, tongue prolapse causes blockage of breathing.
Responsibility
The operation was conducted primarily by the Chechen radical militant group The Special Purpose Islamic Regiment (SPIR), with involvement from the RSRSBCM and International Islamic Brigade. The operation was led by Movsar Barayev.
Military commander Shamil Basayev posted a statement on his website claiming ultimate responsibility for the incident, resigning all official positions within the Chechen government and promising new attacks. He also apologized to Chechnya's elected president and separatist leader Aslan Maskhadov for not informing him of the planned raid and asked him for forgiveness. Basayev defended the hostage-taking for giving "all Russians a first-hand insight into all the charms of the war unleashed by Russia and take it back to where it originated from" and said that his "main goal will be destroying the enemy and exacting maximum damage" and "the next time, those who come won't make any demands, won't take hostages."
The Russian government claimed that wiretapped phone conversations prove that Maskhadov knew of the plans in advance, which he denied. Aslan Maskhadov and his representatives in the West condemned the attack which they said had nothing to do with official policy. Maskhadov said he felt responsible for those "who resorted to self-sacrifice in despair", but also said the "barbaric and inhumane policies" of the Russian leadership were ultimately to blame and criticized the storming of the theater. He offered to start unconditional peace talks with the Russian government to find a political solution to the conflict in Chechnya.
The siege was seen as a public relations disaster for Maskhadov, and his more radical Islamic field commanders correspondingly benefited. Some commentators suggested that Movladi Udugov was in charge from behind the scenes. Russian military expert Pavel Felgenhauer suggested that the aim of the extremist leaders seemed to have been to provoke the Russian government forces "to kill ethnic Russians in Moscow on a large scale", which happened. According to the report by Russian investigators, Zura Barayeva, the widow of Arbi Barayev, led the female members of the group, while a man known as Yasir, identified by his documents as Idris Alkhazurov, was said to be the group's "ideologist" believed to be trained in Saudi Arabia. Russian officials said Chechen militants received financing from groups based in Turkey and that they intercepted telephone calls from the captors to unidentified embassies in Moscow, as well as to Turkey and the United Arab Emirates.
Aftermath
After the raid, Moscow Mayor Yuri Luzhkov said that "the operation was carried out brilliantly by special forces;" he claimed he had wanted a negotiated end to the crisis, but the final attack was made necessary by the reported killing of hostages. The Russian presidential special envoy for human rights in Chechnya, Abdul-Khakim Sultygov, said the bloody outcome was "a good lesson to the terrorists and their accomplices."
Deputy Interior Minister Vasilyev launched a Moscow-wide operation to catch anyone who might have helped the militants, while his superior, Interior Minister Boris Gryzlov, urged people to be vigilant and to report anyone acting suspiciously to police. On 29 October, Vasilyev said he had the authority to state only that special chemical agents had been used and that some 30 suspected militants and their collaborators, including several civil servants and security officers, had been arrested around the theater and in other parts of the city in what Gryzlov called an "unprecedented operation" to identify what he described as a vast terrorist network in Moscow and the surrounding region.
Russian President Vladimir Putin defended the scale and violence of the assault in a televised address later on the morning of 26 October, stating that the government had "achieved the near impossible, saving hundreds... of people" and that the rescue "proved it is impossible to bring Russia to its knees". Putin thanked the special forces as well as the Russian citizens for their "bravery" and the international community for the support given against the "common enemy". He also asked forgiveness for not being able to save more of the hostages, and declared Monday a national day of mourning for those who died. He vowed to continue fighting "international terrorism".
On 29 October, Putin released another televised statement, saying: "Russia will respond with measures that are adequate to the threat to the Russian Federation, striking all the places where the terrorists themselves, the organizers of these crimes and their ideological and financial inspirations are. I stress, wherever they may be located." It was commonly assumed Putin was threatening the former Soviet Republic of Georgia. Putin's comments came as British Prime Minister Tony Blair phoned him to congratulate him on the ending of the siege.
President Putin was unhappy with the coverage of the hostage crisis by NTV, the last nationwide TV channel effectively independent of the government. In January 2003 the management of NTV was replaced, resulting in a profound effect on its editorial policy.
Long-term consequences
The attacks prompted Putin's government to take harsher measures against Chechen separatists. On 28 October, two days after the crisis, he announced that unspecified "measures adequate to the threat" would henceforth be taken in response to terrorist activity, with reports of 30 fighters killed near the Chechen capital Grozny. The Russian Ministry of Defense cancelled plans to reduce the 80,000 troop presence in the tiny breakaway Chechen republic.
In early November, Defense Minister Sergei Ivanov announced Russian forces had launched large-scale operations against separatists throughout Chechnya. The actions of the military caused a new wave of refugees, according to the pro-Moscow Chechen official and the hostage crisis negotiator Aslanbek Aslakhanov.
On 29 May 2008, the European Court of Human Rights (ECHR) unanimously condemned Russia for enforced disappearances in five cases from Chechnya, including the disappearance of two young women in Ulus-Kert (the prosecutor's office initially stated to media that Aminat Dugayeva and Kurbika Zinabdiyeva had been arrested on suspicion of involvement with the Moscow siege).
President Maskhadov's unconditional offer for peace talks with Russia was swiftly dismissed, and Russian Foreign Minister Sergei Lavrov compared such calls with the suggestion that Europe should conduct such talks with the former al-Qaeda leader Osama bin Laden. Russia also accused former Chechen Republic leader Akhmed Zakayev of involvement in the attack. When he visited Denmark for a peace congress in October 2002 (the World Chechen Congress event in Copenhagen), the Russians demanded his arrest and extradition; Zakayev was held for over a month, but was released after Danish authorities stated they were not convinced that sufficient evidence had been provided. The Kremlin also accused the Danish authorities of "solidarity with terrorists" by allowing the meeting of about 100 Chechens, Russian human rights activists and lawmakers from Russia and other European countries to gather and discuss ways to end the fighting.
In early November, the Russian Duma approved a broad array of anti-terrorism legislation ranging from far-reaching restrictions on media coverage of terrorism-related incidents to secret burials for killed terrorists (one lawmaker went as far as to suggest wrapping terrorists' corpses in pigskin and another suggested "carting them around the city with their legs dangling"). The new media law severely restricted the media's reporting of anti-terrorist operations, banning publication or broadcast of "any statement that hinders an operation to break such a siege, or attempts to justify the aims of the hostage-takers". These new policies prompted renewed fears in Russia that Putin was systematically taking control of all Russian media. Sergei Yushenkov, whose Liberal Russia party voted against the change, was quoted by Reuters as saying: "On a wave of emotion, we have in fact legitimised censorship and practically banned criticism of the authorities in emergency situations." Coverage of Chechnya had already been severely restricted, needing the cooperation of both the Russian military and the Moscow-backed Chechen administration (see Russian government censorship of Chechnya coverage). A law by which corpses of people convicted or accused of terrorism would not be released to their families, but disposed of in secret was approved, applying to the bodies of the militants killed in the Moscow crisis, and later applying even to President Maskhadov, who was killed in 2005.
In 2003, Human Rights Watch reported Chechens in Moscow were subjected to increased police harassment after the hostage crisis. Moscow's Chechens rose in numbers from about 20,000 in the Soviet period to an estimated 80,000 in 2002.
Many in the Russian press and in the international media warned that the death of so many hostages in the special forces' rescue operation would severely damage President Putin's popularity. This prediction reportedly turned out to be wrong. Shortly after the siege, the Russian president had record public approval ratings; in December 2002, 83% of Russians reportedly declared themselves satisfied with Putin's rule and his handling of the siege.
Investigation
The official investigation that the Moscow City Prosecutor's Office had been carrying out for three and a half years failed to provide positive information on the gas agent that killed hostages, possible antidote to that agent, the number of hostages released by the operation, the number of militants who had seized the theater (hostages claimed that they saw more than 50 militants, whereas only 40 hostage takers were in the building according to the official version), and the names of officials who had made the decision about the assault. On 1 June 2007, news came that the official investigation had been suspended. The reason provided was that the "culprit had not been located".
The same month, Tatiana Karpova, co-chair of the Nord-Ost Organization of former hostages and families of the dead, demanded a new criminal investigation. She claimed the authorities failed to meet their obligations related to right to life. She stated her concern about the lack of medical care for the injured, and future medical problems for the survivors. In July 2007, relatives of those who died in the hostage-taking urged the Office of the Prosecutor General of Russia to investigate whether senior officials were responsible for the deaths.
Claims of FSB involvement
The Duma refused to consider a proposal by the liberal democratic Union of Rightist Forces party to form an investigative commission charged with probing the government's actions in the theater siege.
An independent investigation of the event was undertaken by Russian politicians Sergei Yushenkov, Sergei Kovalev, journalist Anna Politkovskaya, Hoover Institute scholar John B. Dunlop, and former FSB officers Aleksander Litvinenko and Mikhail Trepashkin. According to their version, the FSB knew about the terrorist group's arrival in Moscow and directed them to the theater through their agent provocateur Khanpasha Terkibayev ("Abu Bakar"), whose name was in the list of hostage takers and who left the theater alive. In April 2003 Litvinenko gave information about Terkibayev ("the Terkibayev file") to Sergei Yushenkov when he visited London. Yushenkov passed this file to Politkovskaya and she was able to interview Terkibayev in person. A few days later, Yushenkov was assassinated by gunfire in Moscow. Terkibayev was later killed in an apparent car crash in Chechnya.
In June 2003, Litvinenko stated in an interview with the Australian television programme Dateline, that two of the Chechen militants involved in the siege—whom he named "Abdul the Bloody" and "Abu Bakar"—were working for the FSB, and that the agency manipulated the terrorists into staging the attack. Litvinenko said: "[w]hen they tried to find [Abdul the Bloody and Abu Bakar] among the rotting corpses of dead terrorists, they weren't there. The FSB got its agents out. So the FSB agents among Chechens organized the whole thing on FSB orders, and those agents were released". "Abu Bakar" (presumably Terkibayev) was also described as an FSB agent and organizer of the theater siege by Anna Politkovskaya, Alexander Khinshtein and other journalists. Sanobar Shermatova and a co-author had pointed out in "Moskovskie novosti" that Terkibaev had for a number of years been involved in "anti-Wahhabi" activities.
John Dunlop identifies "Abu Bakar" as Ruslan Elmurzaev, claimed by Mikhail Trepaskin to have been a resident of Moscow, not Chechnya, and to have been involved in various criminal activities operating out of the Hotel Salyut in Moscow. There were reports that Elmurzaev had not been killed in the storming of the theater. Film director Sergei Govorukhin, one of the volunteer negotiators at Dubrovka, has said that he is convinced that Elmurzaev, who he identified as an FSB agent, is still alive. Russian prosecutors were unable to show Elmurzaev's corpse and during a visit to Chechnya in October 2003, Russian intelligence officers confirmed to him that Elmurzaev was alive and well and living in Chechnya.
The titular leader of the hostage takers was one Movsar Baraev, the nephew of the late and infamous "Wahhabi kidnapper" Arbi Baraev, a figure reported to have shadowy connections to both the FSB and GRU. In January 2003, the French journalist Anne Nivat reported that Baraev had been arrested two months before the hostage-taking incident. This information being true, Baraev was already in Russian custody when the theater siege occurred. Nivat also reported that two of the female hostage takers were also in Russian custody at the time of the siege while late Duma Deputy Yurii Shchekochikhin wrote that another female hostage taker was in custody at the time.
That "Abu Bakar" was in control and not Baraev was supported by an article in "Moskovskie novosti" by journalists Shermatova and Teit, in which it was reported that a hushed conversation between Abu Bakar and Baraev had been accidentally captured by NTV. Baraev declared that the hostage takers had been sent by Shamil Basaev only to be quietly corrected by Abu Bakar to add 'Aslan Maskhadov', in order to link the latter to the hostage taking. As an evidence against Maskhadov, Russians cited a tape first shown on Al Jazeera and subsequently on Russian television, although only a fragment of the original tape was shown on Russian TV. On the original full length tape it was evident that it had been made in late summer, not in October, and had concerned a military operation against federal forces, not an act of hostage taking. Nevertheless, Maskhadov had been discredited although there is no credible evidence to link him with the siege. In the end, it could be said that both the Russian government and the Chechen extremists had achieved their goals; talk of negotiations had ended and Maskhadov's reputation had been damaged.
There is also the figure of Arman Menkeev, a retired major in the GRU and a specialist in making explosive devices. He was arrested by the Interior Ministry in November 2002 at the Moscow Oblast base allegedly used by the terrorists but was released shortly afterwards. He may have subsequently been rearrested but was not charged with a crime and is apparently not in custody. FSB officers, who interrogated Menkeev in Lefortovo prison, classified him as "loyal to the Russian government", adding that "He knows how to keep a military and state secret". The plastic explosive used by the terrorists was in fact "imitation plastic explosives" which had a "Ministry of Defense origin". The Moscow City Prosecutor's Office claimed that Menkeev could have been the source of this material. Apart from two suicide belts, which were more of a danger to the wearers, the bombs placed in the theater (and elsewhere in Moscow prior to the siege) lacked essential elements like batteries; this provided the required conditions for the successful storming of the theater.
Moscow lawsuit and the European Court complaint
After the siege, 61 former hostages sought compensation for physical and emotional suffering totaling almost US$60 million from Moscow city authorities. According to Russia's then-new anti-terrorism law, the region where an act of terror occurs should pay compensation for moral and material damages. Moscow Mayor Yuri Luzhkov's office denounced the suits, saying it could not be held responsible as "the Chechen issue and its consequences are not within the jurisdiction of the Moscow authorities in any way." The Moscow administration earlier agreed to pay 50,000 roubles ($1,570) in compensation to each former hostage and 100,000 roubles ($3,140) to relatives of those killed. In all but one of the cases, Moscow city courts rejected the compensation claims.
In July 2003, 80 plaintiffs from Russia, Ukraine, the Netherlands, and Kazakhstan turned to the European Court for Human Rights, claiming that their right to life had been violated by Russian authorities' handling of the standoff. In April 2007, Igor Trunov, the claimants' advocate, reported that the ECHR had finally begun hearings into a complaint filed in 2003 by the victims against the Russian government. Trunov added that not only Russian citizens, but also those from Ukraine, the Netherlands, and Kazakhstan, filed complaints in the Strasbourg Court. The plaintiffs demand €50,000 each in compensation for the violation of their human rights. The case was accepted by the court in December 2007.
On 8 July 2008, The Moscow Times reported that the hearings at the European Court of Human Rights will be closed to the public at the request of Russian authorities as, according to Igor Trunov, they "have promised full disclosure on how they handled the crisis", including "the makeup of the knockout gas used in the storming of the theater by commandos."
On 20 December 2011, the European Court of Human Rights published its judgement in the case, ordering Russia to pay the 64 applicants a total of 1.3 million euros in compensation. The court also found that Russia had violated Article 2 of the European Convention on Human Rights when handling the hostage crisis, "with inadequate planning and conduct of the rescue operation", and with the "authorities' failure to conduct an effective investigation into the rescue operation", although the Court found that there had been "no violation of Article 2 of the Convention on account of the decision by the authorities to resolve the hostage crisis by force and to use the gas."
Chemical agent mystery and subsequent identification
It was reported that efforts to treat victims were complicated because the Russian government refused to inform doctors what type of gas had been used. In the records of the official investigation, the agent is referred to as a "gaseous substance". In other cases, it is referred to as an "unidentified chemical substance".
The Russian Federation, as a member-state of the Chemical Weapons Convention, undertook "never and under no circumstances to carry out any activities prohibited to member-states of this Convention to develop, to accumulate, to stockpile and to use chemical weapons that can cause death, temporary incapacitation, or permanent harm to humans or animals." The Convention obliges the states to fulfill the conditions of toxic chemicals' use that allow to exclude or considerably reduce the degree of injury and gravity of consequences. (The Convention allows the use of some chemical agents like tear gas for "law enforcement including domestic riot control", but requires that "riot control agents" have effects that "disappear within a short time following termination of exposure.")
Analysis of drug residue from the clothing of two British hostages and the urine of a third British hostage, by a team of researchers at the British chemical and biological defense laboratories at Porton Down, Wiltshire, England, indicated that two fentanyl derivatives had been used. Neither of those two were fentanyl or 3-methylfentanyl (the Russian Minister of Health earlier said that fentanyl or one of its derivatives had been used, but did not specify which derivatives).
The Porton Down analysis by James R. Riches and his colleagues showed that while fentanyl or 3-methylfentanyl were absent from the urine of one survivor and residues of the agent in the clothing of two other British survivors, the veterinary large animal sedative drug carfentanil and anesthetic agent remifentanil were identified by liquid chromatographic tandem mass spectrometry in one hostage's urine and on the clothing of three hostages who had returned to Britain after the hostage rescue. The authors concluded that carfentanil and remifentanil were used as a mixture in the chemical agent employed by Russian troops to subdue the Chechen terrorists and hostages at the Barricade Theater, perhaps suspended in the anesthetic agent halothane.
International reaction
United NationsIn unanimously adopting Resolution 1440 (2002), the United Nations Security Council condemned the attack and demanded the immediate and unconditional release of all hostages. The council also expressed their sympathies and condolences to the victims, Russian people, and government of Russia, and urged all states to cooperate with Russian authorities in bringing those responsible to justice.
Iraqi President Saddam Hussein condemned the attack in a television broadcast, arguing it would ultimately benefit the United States and Israel in undermining Islam: "It's not wise for the Chechens to lose the sympathy of Russia and the Russian people. The tyrant of our era is Zionism and America, and not Russia, China or India."
In popular culture
In 2003, HBO broadcast Terror in Moscow, a documentary directed by Dan Reed. Interviews with hostages and footage taken inside and outside the theater during the crisis are shown.
In 2004 a documentary by the BBC's Horizon investigated the gas that was pumped into the theater.
A Russian DLC released in 2005 for Postal 2 known as "Штопор ЖжОт" (Corkscrew Rules) contains a reference to the attack, in a mission where the protagonist must defend himself from terrorists and police during an attack in a theater.
The 2006 play In Your Hands is based on the events of the Moscow theater siege, written by Natalia Pelevine, opened in London at the New End Theatre. In April 2008, Pelevine said that Russian authorities had banned the play following its Russian debut in the city of Makhachkala, the capital of Dagestan near Chechnya.
The play We Declare You a Terrorist, by Tim J. Lord and based upon the attack, premiered at the 2009 Summer Play Festival.
The 2015 first-person shooter game Tom Clancy's Rainbow Six Siege cites the crisis and FSB response as an inspiration for their hostage rescue game mode.
Part III Episode 6 of the Netflix Spanish drama series Money Heist (La Casa de Papel) contains spoken references to the theater crisis and the use of halothane gas, with critique of Putin's indifference to the fates of the hostages and hostage-takers. In the series, Spanish authorities eventually use halothane gas to assault a bank during a hostage crisis.
In Season 1 Episode 9 of FBI: International, Bulgarian authorities nearly use poison gas to resolve a terrorist hostage-taking in a theater in Sofia, which the Federal Bureau of Investigation, sent to assist Bulgarian authorities, strongly objects to. The standoff is ultimately resolved without the gas being deployed.
The 2020 film Conference (Конференция) follows theater crisis survivor Natasha (Natalya Pavlenko) who returns to the theater to hold a memorial, finally able to confront her survivor's guilt and her estranged daughter and husband. The film is by Russian writer and director Igor I. Tverdovskiy.
Christopher Nolan's movie Tenet, released in August 2020, opens with a prologue that fans and critics have speculated is based on the attack.
See also
List of hostage crises
Crocus City Hall attack
References
Further reading
Report on the crisis and legal proceedings. Published 26 April 2006 (with appendices in Russian).
Nord-Ost. Memorial Book of Lost Hostages. Above site in English, winner of 2007 'Golden Site' award.
}
Moscow hostage crisis: timeline. BBC News. 26 October 2002.
The Hostage Crisis From Start to Finish. The Moscow Times. 28 October 2002.
Moscow theatre siege. BBC News. 4 November 2002.
The October 2002 Moscow Hostage-Taking Incident. Radio Free Europe. 18 December 2003 (Parts 2 and 3).
External links
The Moscow Theatre Siege – transcript. BBC. 15 January 2004.
2002 in Moscow
2002 in theatre
21st-century mass murder in Russia
Attacks on theatres
Chemical weapons attacks
Events in Moscow
Hostage rescue operations
Hostage taking in Russia
Islamic terrorism in Russia
Islamic terrorist incidents in 2002
Massacres committed by Russia
Massacres in 2002
Massacres in the Chechen–Russian conflict
Murder in Moscow
October 2002 events in Russia
Russian special forces operations
Terrorist incidents in Moscow
Terrorist incidents in Russia in 2002
Terrorist incidents of the Second Chechen War | Moscow theater hostage crisis | Chemistry | 9,671 |
596,282 | https://en.wikipedia.org/wiki/Class%20number%20problem | In mathematics, the Gauss class number problem (for imaginary quadratic fields), as usually understood, is to provide for each n ≥ 1 a complete list of imaginary quadratic fields (for negative integers d) having class number n. It is named after Carl Friedrich Gauss. It can also be stated in terms of discriminants. There are related questions for real quadratic fields and for the behavior as .
The difficulty is in effective computation of bounds: for a given discriminant, it is easy to compute the class number, and there are several ineffective lower bounds on class number (meaning that they involve a constant that is not computed), but effective bounds (and explicit proofs of completeness of lists) are harder.
Gauss's original conjectures
The problems are posed in Gauss's Disquisitiones Arithmeticae of 1801 (Section V, Articles 303 and 304).
Gauss discusses imaginary quadratic fields in Article 303, stating the first two conjectures, and discusses real quadratic fields in Article 304, stating the third conjecture.
Gauss conjecture (class number tends to infinity)
Gauss class number problem (low class number lists) For given low class number (such as 1, 2, and 3), Gauss gives lists of imaginary quadratic fields with the given class number and believes them to be complete.
Infinitely many real quadratic fields with class number one Gauss conjectures that there are infinitely many real quadratic fields with class number one.
The original Gauss class number problem for imaginary quadratic fields is significantly different and easier than the modern statement: he restricted to even discriminants, and allowed non-fundamental discriminants.
Status
Gauss conjecture solved, Heilbronn, 1934.
Low class number lists class number 1: solved, Baker (1966), Stark (1967), Heegner (1952).
Class number 2: solved, Baker (1971), Stark (1971)
Class number 3: solved, Oesterlé (1985)
Class numbers h up to 100: solved, Watkins 2004
Infinitely many real quadratic fields with class number one Open.
Lists of discriminants of class number 1
For imaginary quadratic number fields, the (fundamental) discriminants of class number 1 are:
The non-fundamental discriminants of class number 1 are:
Thus, the even discriminants of class number 1, fundamental and non-fundamental (Gauss's original question) are:
Modern developments
In 1934, Hans Heilbronn proved the Gauss conjecture. Equivalently, for any given class number, there are only finitely many imaginary quadratic number fields with that class number.
Also in 1934, Heilbronn and Edward Linfoot showed that there were at most 10 imaginary quadratic number fields with class number 1 (the 9 known ones, and at most one further).
The result was ineffective (see effective results in number theory): it did not give bounds on the size of the remaining field.
In later developments, the case n = 1 was first discussed by Kurt Heegner, using modular forms and modular equations to show that no further such field could exist. This work was not initially accepted; only with later work of Harold Stark and Bryan Birch (e.g. on the Stark–Heegner theorem and Heegner number) was the position clarified and Heegner's work understood. Practically simultaneously, Alan Baker proved what we now know as Baker's theorem on linear forms in logarithms of algebraic numbers, which resolved the problem by a completely different method. The case n = 2 was tackled shortly afterwards, at least in principle, as an application of Baker's work.
The complete list of imaginary quadratic fields with class number 1 is where d is one of
The general case awaited the discovery of Dorian Goldfeld in 1976 that the class number problem could be connected to the L-functions of elliptic curves. This effectively reduced the question of effective determination to one about establishing the existence of a multiple zero of such an L-function. With the proof of the Gross–Zagier theorem in 1986, a complete list of imaginary quadratic fields with a given class number could be specified by a finite calculation. All cases up to n = 100 were computed by Watkins in 2004. The class number of for d = 1, 2, 3, ... is
.
Real quadratic fields
The contrasting case of real quadratic fields is very different, and much less is known. That is because what enters the analytic formula for the class number is not h, the class number, on its own — but h log ε, where ε is a fundamental unit. This extra factor is hard to control. It may well be the case that class number 1 for real quadratic fields occurs infinitely often.
The Cohen–Lenstra heuristics are a set of more precise conjectures about the structure of class groups of quadratic fields. For real fields they predict that about 75.45% of the fields obtained by adjoining the square root of a prime will have class number 1, a result that agrees with computations.
See also
List of number fields with class number one
Notes
References
External links
Algebraic number theory
Mathematical problems
Unsolved problems in number theory | Class number problem | Mathematics | 1,079 |
18,460,129 | https://en.wikipedia.org/wiki/Seratrodast | Seratrodast (development name, AA-2414; marketed originally as Bronica) is a thromboxane A2 (TXA2) receptor (TP receptor) antagonist used primarily in the treatment of asthma. It was the first TP receptor antagonist that was developed as an anti-asthmatic drug and received marketing approval in Japan in 1997. As of 2017 seratrodast was marketed as Bronica in Japan, and as Changnuo, Mai Xu Jia, Quan Kang Nuo in China.
Unlike thromboxane synthase inhibitors such as ozagrel, seratrodast does not affect thrombus formation, time to occlusion and bleeding time. Seratrodast has no effect on prothrombin time and activated partial thromboplastin time, thus ruling out any action on blood coagulation cascade.
Medical uses
Seratrodast is used to treat asthma.
There are no adequate and well-controlled studies of seratrodast in pregnant women. The drug should be used in pregnancy only if the potential benefits justify the risk to the fetus. Seratrodast should not be used during lactation.
The safety and efficacy of seratrodast has not been established in children (<18 years of age).
Contraindications and interactions
Seratrodast should not be used in people with liver disease.
Use with paracetamol or with cephem antibiotics increases the risk of liver damage. Use with aspirin increases the bioavailability of seratrodast.
Adverse effects
The most frequently observed (0.1 to 5%) adverse reactions include elevated transaminases, nausea, loss of appetite, stomach discomfort, abdominal pain, diarrhea, constipation, dry mouth, taste disturbance, drowsiness, headache, dizziness, palpitations and malaise. Less than 0.1% of patients experienced vomiting, thrombocytopenia, epistaxis, bleeding tendency, insomnia, tremor, numbness, hot flushes and edema. All the adverse reactions reported were of mild to moderate severity, and resolved when the drug was discontinued.
Pharmacology
Thromboxane A2 (TXA2) is generated in the lungs of people with asthma, and when it signals through the thromboxane receptor it causes bronchoconstriction, vasoconstriction, mucous secretion, and airway hyper-responsiveness. Seratrodast inhibits the activity of the thromboxane receptor, blocking the effects of TXA2.
Pharmacokinetics
The pharmacokinetics of seratrodast have been studied in Japanese and Caucasian, including Indian, healthy volunteers. The plasma concentrations of seratrodast increase with increasing doses. The absorption of seratrodast is relatively rapid with maximum plasma concentrations of 4.6–6 μg/ml obtained in 3 to 4 hours. Steady state plasma concentrations of seratrodast are reached within 4–5 days. Seratrodast is slowly cleared, mainly by hepatic biotransformation. The drug shows biexponential decay in plasma profiles with a mean elimination half-life of 22 hours. Approximately 20% of the administered dose is recovered in the urine, with 60% of the urinary recovery being in the form of conjugates
Chemistry
Seratrodast can be prepared in five steps starting from pimelic acid monoester.
History
Seratrodast was the first thromboxane receptor antagonist to reach the market as a treatment for asthma; it was approved in Japan in 1997.
Society and culture
As of 2017 seratrodast was marketed as Bronica in Japan, Changnuo, Mai Xu Jia, Quan Kang Nuo in China and as Seretra & Seradair in India.
Research
Seratrodast was studied in perennial allergic rhinitis, chronic bronchitis and chronic pulmonary emphysema but efforts to bring the drug to market in those indications was abandoned around 2000.
References
1,4-Benzoquinones
Carboxylic acids | Seratrodast | Chemistry | 850 |
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