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https://en.wikipedia.org/wiki/Sum-free%20sequence | In mathematics, a sum-free sequence is an increasing sequence of positive integers,
such that no term can be represented as a sum of any subset of the preceding elements of the sequence.
This differs from a sum-free set, where only pairs of sums must be avoided, but where those sums may come from the whole set rather than just the preceding terms.
Example
The powers of two,
1, 2, 4, 8, 16, ...
form a sum-free sequence: each term in the sequence is one more than the sum of all preceding terms, and so cannot be represented as a sum of preceding terms.
Sums of reciprocals
A set of integers is said to be small if the sum of its reciprocals converges to a finite value. For instance, by the prime number theorem, the prime numbers are not small. proved that every sum-free sequence is small, and asked how large the sum of reciprocals could be. For instance, the sum of the reciprocals of the powers of two (a geometric series) is two.
If denotes the maximum sum of reciprocals of a sum-free sequence, then through subsequent research it is known that .
Density
It follows from the fact that sum-free sequences are small that they have zero Schnirelmann density; that is, if is defined to be the number of sequence elements that are less than or equal to , then . showed that for every sum-free sequence there exists an unbounded sequence of numbers for which where is the golden ratio, and he exhibited a sum-free sequence for which, for all values of , , subsequently improved to by Deshouillers, Erdős and Melfi in 1999 and to by Luczak and Schoen in 2000, who also proved that the exponent 1/2 cannot be further improved.
Notes |
https://en.wikipedia.org/wiki/Bioeconomy | Biobased economy, bioeconomy or biotechonomy is economic activity involving the use of biotechnology and biomass in the production of goods, services, or energy. The terms are widely used by regional development agencies, national and international organizations, and biotechnology companies. They are closely linked to the evolution of the biotechnology industry and the capacity to study, understand, and manipulate genetic material that has been possible due to scientific research and technological development. This includes the application of scientific and technological developments to agriculture, health, chemical, and energy industries. The terms bioeconomy (BE) and bio-based economy (BBE) are sometimes used interchangeably. However, it is worth to distinguish them: the biobased economy takes into consideration the production of non-food goods, whilst bioeconomy covers both bio-based economy and the production and use of food and feed. More than 60 countries and regions have bioeconomy or bioscience-related strategies, of which 20 have published dedicated bioeconomy strategies in Africa, Asia, Europe, Oceania, and the Americas.
Definitions
Bioeconomy has large variety of definitions. The bioeconomy comprises those parts of the economy that use renewable biological resources from land and sea – such as crops, forests, fish, animals and micro-organisms – to produce food, health, materials, products, textiles and energy. The definitions and usage does however vary between different areas of the world.
An important aspect of the bioeconomy is understanding mechanisms and processes at the genetic, molecular, and genomic levels, and applying this understanding to creating or improving industrial processes, developing new products and services, and producing new energy. Bioeconomy aims to reduce our dependence on fossil natural resources, to prevent biodiversity loss and to create new economic growth and jobs that are in line with the principles of sustainable develo |
https://en.wikipedia.org/wiki/Tutte%20matrix | In graph theory, the Tutte matrix A of a graph G = (V, E) is a matrix used to determine the existence of a perfect matching: that is, a set of edges which is incident with each vertex exactly once.
If the set of vertices is then the Tutte matrix is an n × n matrix A with entries
where the xij are indeterminates. The determinant of this skew-symmetric matrix is then a polynomial (in the variables xij, i < j ): this coincides with the square of the pfaffian of the matrix A and is non-zero (as a polynomial) if and only if a perfect matching exists. (This polynomial is not the Tutte polynomial of G.)
The Tutte matrix is named after W. T. Tutte, and is a generalisation of the Edmonds matrix for a balanced bipartite graph. |
https://en.wikipedia.org/wiki/Alcuin%27s%20sequence | In mathematics, Alcuin's sequence, named after Alcuin of York, is the sequence of coefficients of the power-series expansion of:
The sequence begins with these integers:
0, 0, 0, 1, 0, 1, 1, 2, 1, 3, 2, 4, 3, 5, 4, 7, 5, 8, 7, 10, 8, 12, 10, 14, 12, 16, 14, 19, 16, 21
The nth term is the number of triangles with integer sides and perimeter n. It is also the number of triangles with distinct integer sides and perimeter n + 6, i.e. number of triples (a, b, c) such that 1 ≤ a < b < c < a + b, a + b + c = n + 6.
If one deletes the three leading zeros, then it is the number of ways in which n empty casks, n casks half-full of wine and n full casks can be distributed to three persons in such a way that each one gets the same number of casks and the same amount of wine. This is the generalization of problem 12 appearing in Propositiones ad Acuendos Juvenes ("Problems to Sharpen the Young") usually attributed to Alcuin. That problem is given as,
Problem 12: A certain father died and left as an inheritance to his three sons 30 glass flasks, of which 10 were full of oil, another 10 were half full, while another 10 were empty. Divide the oil and flasks so that an equal share of the commodities should equally come down to the three sons, both of oil and glass.
The term "Alcuin's sequence" may be traced back to D. Olivastro's 1993 book on mathematical games, Ancient Puzzle: Classical Brainteasers and Other Timeless Mathematical Games of the Last 10 Centuries (Bantam, New York).
The sequence with the three leading zeros deleted is obtained as the sequence of coefficients of the power-series expansion of
This sequence has also been called Alcuin's sequence by some authors. |
https://en.wikipedia.org/wiki/Common%20graph | In graph theory, an area of mathematics, common graphs belong to a branch of extremal graph theory concerning inequalities in homomorphism densities. Roughly speaking, is a common graph if it "commonly" appears as a subgraph, in a sense that the total number of copies of in any graph and its complement is a large fraction of all possible copies of on the same vertices. Intuitively, if contains few copies of , then its complement must contain lots of copies of in order to compensate for it.
Common graphs are closely related to other graph notions dealing with homomorphism density inequalities. For example, common graphs are a more general case of Sidorenko graphs.
Definition
A graph is common if the inequality:
holds for any graphon , where is the number of edges of and is the homomorphism density.
The inequality is tight because the lower bound is always reached when is the constant graphon .
Interpretations of definition
For a graph , we have and for the associated graphon , since graphon associated to the complement is . Hence, this formula provides us with the very informal intuition to take a close enough approximation, whatever that means, to , and see as roughly the fraction of labeled copies of graph in "approximate" graph . Then, we can assume the quantity is roughly and interpret the latter as the combined number of copies of in and . Hence, we see that holds. This, in turn, means that common graph commonly appears as subgraph.
In other words, if we think of edges and non-edges as 2-coloring of edges of complete graph on the same vertices, then at least fraction of all possible copies of are monochromatic. Note that in a Erdős–Rényi random graph with each edge drawn with probability , each graph homomorphism from to have probability of being monochromatic. So, common graph is a graph where it attains its minimum number of appearance as a monochromatic subgraph of graph at the graph with
. The above definition usin |
https://en.wikipedia.org/wiki/Myeloma%20protein | A myeloma protein is an abnormal antibody (immunoglobulin) or (more often) a fragment thereof, such as an immunoglobulin light chain, that is produced in excess by an abnormal monoclonal proliferation of plasma cells, typically in multiple myeloma or Monoclonal gammopathy of undetermined significance. Other terms for such a protein are monoclonal protein, M protein, M component, M spike, spike protein, or paraprotein. This proliferation of the myeloma protein has several deleterious effects on the body, including impaired immune function, abnormally high blood viscosity ("thickness" of the blood), and kidney damage.
History
The concept and the term paraprotein were introduced by the Berlin pathologist Dr Kurt Apitz in 1940, then the senior physician of the pathological institute at the Charité hospital.
Paraproteins allowed the detailed study of immunoglobulins, which eventually led to the production of monoclonal antibodies in 1975.
Cause
Myeloma is a malignancy of plasma cells. Plasma cells produce immunoglobulins, which are commonly called antibodies. There are thousands of different antibodies, each consisting of pairs of heavy and light chains. Antibodies are typically grouped into five classes: IgA, IgD, IgE, IgG, and IgM. When someone has myeloma, a malignant clone, a rogue plasma cell, reproduces in an uncontrolled fashion, resulting in overproduction of the specific antibody the original cell was generated to produce. Each type of antibody has a different number of light chain and heavy chain pairs. As a result, there is a characteristic normal distribution of these antibodies in the blood by molecular weight.
When there is a malignant clone, there is usually overproduction of a single antibody, resulting in a "spike" on the normal distribution (sharp peak on the graph), which is called an M spike (or monoclonal spike). People will sometimes develop a condition called MGUS (Monoclonal gammopathy of undetermined significance), where there is ove |
https://en.wikipedia.org/wiki/Signed%20graph | In the area of graph theory in mathematics, a signed graph is a graph in which each edge has a positive or negative sign.
A signed graph is balanced if the product of edge signs around every cycle is positive. The name "signed graph" and the notion of balance appeared first in a mathematical paper of Frank Harary in 1953. Dénes Kőnig had already studied equivalent notions in 1936 under a different terminology but without recognizing the relevance of the sign group.
At the Center for Group Dynamics at the University of Michigan, Dorwin Cartwright and Harary generalized Fritz Heider's psychological theory of balance in triangles of sentiments to a psychological theory of balance in signed graphs.
Signed graphs have been rediscovered many times because they come up naturally in many unrelated areas. For instance, they enable one to describe and analyze the geometry of subsets of the classical root systems. They appear in topological graph theory and group theory. They are a natural context for questions about odd and even cycles in graphs. They appear in computing the ground state energy in the non-ferromagnetic Ising model; for this one needs to find a largest balanced edge set in Σ. They have been applied to data classification in correlation clustering.
Fundamental theorem
The sign of a path is the product of the signs of its edges. Thus a path is positive only if there are an even number of negative edges in it (where zero is even). In the mathematical balance theory of Frank Harary, a signed graph is balanced when every cycle is positive. Harary proves that a signed graph is balanced when (1) for every pair of nodes, all paths between them have the same sign, or (2) the vertices partition into a pair of subsets (possibly empty), each containing only positive edges, but connected by negative edges. It generalizes the theorem that an ordinary (unsigned) graph is bipartite if and only if every cycle has even length.
A simple proof uses the method of switchi |
https://en.wikipedia.org/wiki/JASBUG | JASBUG is a security bug disclosed in February 2015 and affecting core components of the Microsoft Windows Operating System. The vulnerability dated back to 2000 and affected all supported editions of Windows Server 2003, Windows Vista, Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows 8, Windows Server 2012, Windows RT, Windows 8.1, Windows Server 2012 R2, and Windows RT 8.1.
The vulnerability allows hackers to remotely take control of Windows devices that connect to an Active Directory domain.
JASBUG is registered in the Common Vulnerabilities and Exposures system as . The Industrial Control Systems Cyber Emergency Response Team, part of the Department of Homeland Security, issued ICS-ALERT-15-041-01, warning control systems owners that they should expedite applying critical JASBUG fixes.
Microsoft released two patches, MS15-011 and MS15-014, to address JASBUG on the same day the vulnerability was disclosed. These fixes took Microsoft over a year to develop and deploy due to the complexity of the JASBUG vulnerability.
At the time of disclosure, more than 300 million computers were believed to be vulnerable to the exploit.
History
JASBUG was disclosed to the public by Microsoft as a part of "Patch Tuesday," on February 10, 2015.
Background
The vulnerability was initially reported to Microsoft in January 2014 by Jeff Schmidt, founder of JAS Global Advisors. After Microsoft publicly announced the security vulnerability, it garnered the name JASBUG in reference to the role JAS Global Advisors played in discovering the exploit.
Discovery
In 2014, JAS Global Advisors was working on an engagement with the Internet Corporation for Assigned Names and Numbers (ICANN), the organization governing the standards of the Internet, to research potential technical issues surrounding the rollout of new Generic Top Level Domains (gTLDs) on the Internet.
While working on the research, JAS Global Advisors, with business partner SimMachines, uncovered the vu |
https://en.wikipedia.org/wiki/Outpost%20%28military%29 | A military outpost is detachment of troops stationed at a distance from the main force or formation, usually at a station in a remote or sparsely populated location, positioned to stand guard against unauthorized intrusions and surprise attacks; and the station occupied by such troops, usually a small military base or settlement in an outlying frontier, limit, political boundary or in another country. Outposts can also be called miniature military bases based on size and number of troops it houses.
Recent military use
Military outposts, most recently referred to as combat outposts (COPs), served as a cornerstone of counterinsurgency doctrine in Iraq and Afghanistan. These permanent or semi-permanent structures, often located in or near populated areas, enabled military forces to secure key lines of communication or infrastructure, secure and co-opt the populace, assist the government in restoring essential services, and force insurgents to operate elsewhere. Combat Outposts were almost unanimously described in positive terms by defense analysts and military officers as a means through which to carry out its counterinsurgency efforts.
See also
Satellite airfield
Forward operating base
Border outpost
Observation post
Human outpost
Blockhouse
Military base
Screening (tactic) |
https://en.wikipedia.org/wiki/Newsdiary%20online | The News Diary is a daily online newspaper in Abuja, Nigeria published by Newsdiary Communication Limited (NCL).
About
The News Diary was founded by Newsdiary Group Limited in 2009 as online news content, the NGL was founded by Danlami Nmodu, a columnist who was also publisher in TheNEWS and Tempo magazine.
In 2015, the head office in Abuja was burgled by unknown people in aspect to some vita information and office useful items were stolen said by chief-editor Danlami Nmodu.
DSS Nigeria
In December 2019 the Department of State Services (DSS) boss Yusuf Magaji Bichi, invited the chief-editor of Newsdiary Mr Danlami Nmodu on a phone call to their headquarters in Abuja over a recent leaked publication of a story title Diplomatic backlash, legal tussle looms as Federal Government dumps German firm over Kano project on ecological funds projects in Kano after the published story the secretary to the state government office and head Boss Mustapha hits with available fact that clarify the issue and the newspaper had participate on Challawa, Sharaba and Bompai ecological projects of $7.5 million in Kano State the department of state services quoted to know how it was leaked.
Notes
External links
Official website
Daily newspapers published in Nigeria
Newspapers published in Abuja
2009 establishments in Nigeria
Online content distribution
Online newspapers with defunct print editions
Online newspapers published in Nigeria |
https://en.wikipedia.org/wiki/Integrity%20%28operating%20system%29 | INTEGRITY and INTEGRITY-178B are real-time operating systems (RTOSes) produced and marketed by Green Hills Software.
INTEGRITY
INTEGRITY is POSIX-certified and intended for use in embedded systems of 32-bits or 64-bits. Supported computer architectures include variants of: ARM, Blackfin, ColdFire, MIPS, PowerPC, XScale, and x86. INTEGRITY is supported by popular SSL/TLS libraries such as wolfSSL.
INTEGRITY-178B
INTEGRITY-178B is the DO-178B–compliant version of INTEGRITY. It is used in several military jets such as the B-2, F-16, F-22, and F-35, and the commercial aircraft Airbus A380. Its kernel design guarantees bounded computing times by eliminating features such as dynamic memory allocation.
The auditing and security engineering abilities have allowed it to obtain the Evaluation Assurance Level (EAL) 6 rating by the National Security Agency (NSA). The Target of Evaluation (TOE) Architecture in the Security Target for the evaluation excludes components such as those for file system and networking, from the definition of the TOE, focusing almost solely on the core kernel. Other operating systems, such as Windows, macOS or Linux, though evaluated at lower levels of assurance, generally include these abilities within their TOE.
Supported processor architectures
The INTEGRITY Architecture Support Package (ASP) provides support for many processor families:
PowerPC/Power ISA
AMD and Intel: x86
ARM Holdings: ARM
MIPS |
https://en.wikipedia.org/wiki/Crossover%20interference | Crossover interference is the term used to refer to the non-random placement of crossovers with respect to each other during meiosis. The term is attributed to Hermann Joseph Muller, who observed that one crossover "interferes with the coincident occurrence of another crossing over in the same pair of chromosomes, and I have accordingly termed this phenomenon ‘interference’."
Meiotic crossovers (COs) appear to be regulated to ensure that COs on the same chromosome are distributed far apart (crossover interference). In the nematode worm Caenorhabditis elegans, meiotic double-strand breaks (DSBs) outnumber COs. Thus not all DSBs are repaired by a recombination process(es) leading to COs. The RTEL-1 protein is required to prevent excess meiotic COs. In rtel-1 mutants meiotic CO recombination is significantly increased and crossover interference appears to be absent. RTEL1 likely acts by promoting synthesis-dependent strand annealing which results in non-crossover (NCO) recombinants instead of COs (see diagram). Normally, about half of all DSBs are converted into NCOs. RTEL-1 appears to enforce meiotic crossover interference by directing the repair of some DSBs towards NCOs rather than COs.
In humans, recombination rate increases with maternal age. Furthermore, placement of female recombination events appears to become increasingly deregulated with maternal age, with a larger fraction of events occurring within closer proximity to each other than would be expected under simple models of crossover interference.
High negative interference
Bacteriophage T4
High negative interference (HNI), in contrast to positive interference, refers to the association of recombination events ordinarily measured over short genomic distances, usually within a gene. Over such short distances there is a positive correlation (negative interference) of recombinational events. As studied in bacteriophage T4 this correlation is greater the shorter the interval between the sites us |
https://en.wikipedia.org/wiki/Cross-polarization | Cross-polarization (CP), originally published as proton-enhanced nuclear induction spectroscopy is a solid-state nuclear magnetic resonance (ssNMR) technique to transfer nuclear magnetization from different types of nuclei via heteronuclear dipolar interactions. The 1H-X cross-polarization dramatically improves the sensitivity of ssNMR experiments of most experiments involving spin-1/2 nuclei, capitalizing on the higher 1H polarisation, and shorter T1(1H) relaxation times. It was developed by Michael Gibby, Alexander Pines and Professor John S. Waugh at the Massachusetts Institute of Technology.
In this technique the natural nuclear polarization of an abundant spin (typically 1H) is exploited to increase the polarization of a rare spin (such as 13C, 15N, 31P) by irradiating the sample with radio waves at the frequencies matching the Hartmann–Hahn condition:
where are the gyromagnetic ratios, is the spinning rate, and is an integer. This process is sometimes referred to as "spin-locking". The power of one contact pulse is typically ramped to achieve a more broadband and efficient magnetisation transfer.
The evolution of the X NMR signal intensity during the cross polarisation is a build-up and decay process whose time axis is usually referred to as the "contact time". At short CP contact times, a build-up of X magnetisation occurs, during which the transfer of 1H magnetisation from nearby spins (and remote spins through proton spin diffusion) to X occurs. For longer CP contact times, the X magnetisation decreases from T1ρ(X) relaxation, i.e. the decay of the magnetisation during a spin lock. |
https://en.wikipedia.org/wiki/Iron%28II%2CIII%29%20oxide | Iron(II,III) oxide, or black iron oxide, is the chemical compound with formula Fe3O4. It occurs in nature as the mineral magnetite. It is one of a number of iron oxides, the others being iron(II) oxide (FeO), which is rare, and iron(III) oxide (Fe2O3) which also occurs naturally as the mineral hematite. It contains both Fe2+ and Fe3+ ions and is sometimes formulated as FeO ∙ Fe2O3. This iron oxide is encountered in the laboratory as a black powder. It exhibits permanent magnetism and is ferrimagnetic, but is sometimes incorrectly described as ferromagnetic. Its most extensive use is as a black pigment (see: Mars Black). For this purpose, it is synthesized rather than being extracted from the naturally occurring mineral as the particle size and shape can be varied by the method of production.
Preparation
Heated iron metal interacts with steam to form iron oxide and hydrogen gas.
3Fe + 4H2O->Fe3O4 + 4H2
Under anaerobic conditions, ferrous hydroxide (Fe(OH)2) can be oxidized by water to form magnetite and molecular hydrogen. This process is described by the Schikorr reaction:
\underset{ferrous\ hydroxide}{3Fe(OH)2} -> \underset{magnetite}{Fe3O4} + \underset{hydrogen}{H2} + \underset{water}{2H2O}
This works because crystalline magnetite (Fe3O4) is thermodynamically more stable than amorphous ferrous hydroxide (Fe(OH)2 ).
The Massart method of preparation of magnetite as a ferrofluid, is convenient in the laboratory: mix iron(II) chloride and iron(III) chloride in the presence of sodium hydroxide.
A more efficient method of preparing magnetite without troublesome residues of sodium, is to use ammonia to promote chemical co-precipitation from the iron chlorides: first mix solutions of 0.1 M FeCl3·6H2O and FeCl2·4H2O with vigorous stirring at about 2000 rpm. The molar ratio of the FeCl3:FeCl2 should be about 2:1. Heat the mix to 70 °C, then raise the speed of stirring to about 7500 rpm and quickly add a solution of NH4OH (10 volume %). A dark precipitate of nanopart |
https://en.wikipedia.org/wiki/Climax%20species | Climax species, also called late seral, late-successional, K-selected or equilibrium species, are plant species that can germinate and grow with limited resources; e.g., they need heat exposure or low water availability. They are the species within forest succession that are more adapted to stable and predictable environments, and will remain essentially unchanged in terms of species composition for as long as a site remains undisturbed.
The seedlings of climax species can grow in the shade of the parent trees, ensuring their dominance indefinitely. The presence of climax species can also reduce the prevalence of other species within an ecosystem. However, a disturbance, such as fire, may kill the climax species, allowing pioneer or earlier successional species to re-establish for a time. They are the opposite of pioneer species, also known as ruderal, fugitive, opportunistic or R-selected species, in the sense that climax species are good competitors but poor colonizers, whereas pioneer species are good colonizers but poor competitors.
Given the prevailing ecological conditions, climax species dominate the climax community. When the pace of succession slows down as the result of ecological homeostasis, the maximum permitted biodiversity is reached. Their reproductive strategies and other adaptive characteristics can be considered more sophisticated than those of opportunistic species.
Through negative feedback, they adapt themselves to specific environmental conditions. Climax species are mostly found in forests. Climax species, closely controlled by carrying capacity, follow K strategies, wherein species produce fewer numbers of potential offspring, but invest more heavily in securing the reproductive success of each one to the micro-environmental conditions of its specific ecological niche. Climax species might be iteroparous, energy consumption efficient and nutrient cycling.
Disputed term
The idea of a climax species has been criticized in recent ecolog |
https://en.wikipedia.org/wiki/Cyclodipeptide%20synthases | Cyclodipeptide synthases (CDPSs) are a newly defined family of peptide-bond forming enzymes that are responsible for the ribosome-independent biosynthesis of various cyclodipeptides, which are the precursors of many natural products with important biological activities. As a substrate for this synthesis, CDPSs use two amino acids activated as aminoacyl-tRNAs (aa-tRNAs), therefore diverting them from the ribosomal machinery. The first member of this family was identified in 2002 during the characterization of the albonoursin biosynthetic pathway in Streptomyces noursei. CDPSs are present in bacteria, fungi, and animal cells.
History and research
From 2002, when the first description of a CDPSs was done, until now, the number of reported CDPSs in databases has experienced a significant growth (800 in June 2017). It is probable that these cyclopeptides are implicated in numerous biosynthetic pathways. However, their products’ diversity has not been very explored. The activity of 32 new CPDS has been described. This fact raises the number of experimentally characterized CDPS up to 100 (approximately). Moreover, this research has identified several consensus sequences associated to the formation of a specific cyclodipeptide, enhancing the predictive model of specificity of CDPS. This improved prediction method facilitates the deciphering of independent ways of CDPS.
Structure
CDPSs don’t have a specific structure, given each one has its own specific function, but they still have common architectures, such as a Rossmann-fold domain. CDPSs are monomers that have been found to display a strong structural similarity to the catalytic domains of class Ic aminoacyl tRNA synthetases: both these families, CDPSs and class Ic aaRSs, have a Rossmann-fold domain and their structures can be superimposed showing many structural analogies.
CDPSs characteristically feature a deep surface-accessible pocket bordered by the catalytic residues, which is where the catalysis of amide bond |
https://en.wikipedia.org/wiki/Aleksei%20Markushevich | Aleksei Ivanovich Markushevich (; , Petrozavodsk – 7 June 1979, Moscow) was a Soviet mathematician, mathematical educator, and historian of mathematics. He is known for the Farrell–Markushevich theorem.
Biography
Markushevich's father worked as a junior architect for the Olonets provincial government. In 1916 the family moved to Semipalatinsk, where he graduated from secondary school in 1924. In 1925 he matriculated at the First Central Asian State University (now the National University of Uzbekistan). There in 1930 he graduated and was admitted to the correspondence course (education by mail) of the graduate school. In autumn 1931 he became a graduate student in the Research Institute of Mechanics and Mathematics, Moscow State University. There he received in 1934 his Aspirantur (similar to a PhD) under the supervision of Mikhail Lavrentyev, became at the beginning of 1935 a senior researcher, and became in 1938 an associate professor. At Moscow State University, Markushevich received in 1944 his Russian Doctor of Sciences degree (habilitation) and in 1946 became a full professor, retaining that academic position until his death.
Markushevich was elected in 1945 a corresponding member and in 1950 a full member of Академии педагогических наук РСФСР (Academy of Pedagogical Sciences, Russian Soviet Federative Socialist Republic). For that academy he served as vice-president from 1950 to 1958 and again from 1964 to 1967. From 1958 to 1964 he was the primary deputy minister of education of the Russian Soviet Federative Socialist Republic.
In Академии педагогических наук СССР (Academy of Pedagogical Sciences of the USSR), he was elected a full member in 1967 and served as its vice-president from 1967 to 1975.
In 1978 he was an Invited Speaker at the International Congress of Mathematicians (ICM) in Helsinki.
The last years of his life were overshadowed by a scandal related to the theft of medieval European manuscripts from Российский государственный архив древних |
https://en.wikipedia.org/wiki/CEN/XFS | CEN/XFS or XFS (extensions for financial services) provides a client-server architecture for financial applications on the Microsoft Windows platform, especially peripheral devices such as EFTPOS terminals and ATMs which are unique to the financial industry. It is an international standard promoted by the European Committee for Standardization (known by the acronym CEN, hence CEN/XFS). The standard is based on the WOSA Extensions for Financial Services or WOSA/XFS developed by Microsoft.
With the move to a more standardized software base, financial institutions have been increasingly interested in the ability to pick and choose the application programs that drive their equipment. XFS provides a common API for accessing and manipulating various financial services devices regardless of the manufacturer.
History
Chronology:
1991 - Microsoft forms "Banking Solutions Vendor Council"
1995 - WOSA/XFS 1.11 released
1997 - WOSA/XFS 2.0 released - additional support for 24 hours-a-day unattended operation
1998 - adopted by European Committee for Standardization as an international standard.
2000 - XFS 3.0 released by CEN
2008 - XFS 3.10 released by CEN
2011 - XFS 3.20 released by CEN
2015 - XFS 3.30 released by CEN
2020 - XFS 3.40 released by CEN
WOSA/XFS changed name to simply XFS when the standard was adopted by the international CEN/ISSS standards body. However, it is most commonly called CEN/XFS by the industry participants.
XFS middleware
While the perceived benefit of XFS is similar to Java's "write once, run anywhere" mantra, often different hardware vendors have different interpretations of the XFS standard. The result of these differences in interpretation means that applications typically use a middleware to even out the differences between various platforms implementation of XFS.
Notable XFS middleware platforms include:
F1 Solutions - F1 TPS (multi-vendor ATM & POS solution)
Serquo - Dwide (REST API middleware for XFS)
Nexus Software LLC - Nexu |
https://en.wikipedia.org/wiki/Bragg%20plane | In physics, a Bragg plane is a plane in reciprocal space which bisects a reciprocal lattice vector, , at right angles. The Bragg plane is defined as part of the Von Laue condition for diffraction peaks in x-ray diffraction crystallography.
Considering the adjacent diagram, the arriving x-ray plane wave is defined by:
Where is the incident wave vector given by:
where is the wavelength of the incident photon. While the Bragg formulation assumes a unique choice of direct lattice planes and specular reflection of the incident X-rays, the Von Laue formula only assumes monochromatic light and that each scattering center acts as a source of secondary wavelets as described by the Huygens principle. Each scattered wave contributes to a new plane wave given by:
The condition for constructive interference in the direction is that the path difference between the photons is an integer multiple (m) of their wavelength. We know then that for constructive interference we have:
where . Multiplying the above by we formulate the condition in terms of the wave vectors, and :
Now consider that a crystal is an array of scattering centres, each at a point in the Bravais lattice. We can set one of the scattering centres as the origin of an array. Since the lattice points are displaced by the Bravais lattice vectors, , scattered waves interfere constructively when the above condition holds simultaneously for all values of which are Bravais lattice vectors, the condition then becomes:
An equivalent statement (see mathematical description of the reciprocal lattice) is to say that:
By comparing this equation with the definition of a reciprocal lattice vector, we see that constructive interference occurs if is a vector of the reciprocal lattice. We notice that and have the same magnitude, we can restate the Von Laue formulation as requiring that the tip of incident wave vector, , must lie in the plane that is a perpendicular bisector of the reciprocal lattice vector, . This rec |
https://en.wikipedia.org/wiki/Cromemco%20Cyclops | The Cromemco Cyclops, introduced in 1975 by Cromemco, was the first commercial all-digital camera using a digital metal–oxide–semiconductor (MOS) image sensor. It was also the first digital camera to be interfaced to a microcomputer. The digital sensor for the camera was a modified 1kb dynamic RAM (DRAM) memory chip that offered a resolution of 32 × 32 pixels (0.001 megapixels).
Background
The Cyclops Camera was developed by Terry Walker, Harry Garland, and Roger Melen, and introduced as a hobbyist construction project in the February 1975 issue of Popular Electronics magazine.
One month earlier the MITS Altair 8800 microcomputer had been introduced in this same magazine. Les Solomon, technical editor of Popular Electronics, saw the value of interfacing the Cyclops to the Altair, and put Roger Melen (co-developer of the Cyclops) in contact with Ed Roberts (president of MITS) to discuss a collaboration.
Roger Melen met with Ed Roberts at MITS headquarters in Albuquerque, New Mexico. Roberts encouraged Melen to interface the Cyclops to the Altair, promising to ship Melen an early Altair computer so that he and his colleagues could begin work on this project.
Roger Melen formed a partnership with Harry Garland to produce the Cyclops Camera, and other products for the Altair computer. They named their new venture "Cromemco" after the Stanford University dormitory (Crothers Memorial Hall) where they both had lived as graduate students. In January 1976 MITS introduced the Cromemco Cyclops Camera as the first peripheral for the Altair Computer.
Technology
The Cyclops Camera used an innovative image sensor that was actually a modified MOS computer memory chip. The opaque cover on the chip was removed and replaced with a glass lid. The theory of operation was described in the original Popular Electronics article. Initially the 1024 memory locations, which were arranged in a 32 × 32 array, were filled with all 1s. Light shining on these memory cells would cause their |
https://en.wikipedia.org/wiki/Grimm%27s%20hydride%20displacement%20law | Grimm's Hydride Displacement Law is an early hypothesis, formulated in 1925, to describe bioisosterism, the ability of certain chemical groups to function as or mimic other chemical groups.
“Atoms anywhere up to four places in the periodic system before an inert gas change their properties by uniting with one to four hydrogen atoms, in such a manner that the resulting combinations behave like pseudoatoms, which are similar to elements in the groups one to four places respectively, to their right.”
According to Grimm, each vertical column (of Table below) would represent a group of isosteres. |
https://en.wikipedia.org/wiki/Bandwidth%20Broker | RFC 2638 from the IETF defines the entity of the Bandwidth Broker (BB) in the framework of differentiated services (DiffServ). According to RFC 2638, a Bandwidth Broker is an agent that has some knowledge of an organization's priorities and policies and allocates quality of service (QoS) resources with respect to those policies. In order to achieve an end-to-end allocation of resources across separate domains, the Bandwidth Broker managing a domain will have to communicate with its adjacent peers, which allows end-to-end services to be constructed out of purely bilateral agreements. Admission control is one of the main tasks that a Bandwidth Broker has to perform, in order to decide whether an incoming resource reservation request will be accepted or not. Most Bandwidth Brokers use simple admission control modules, although there are also proposals for more sophisticated admission control according to several metrics such as acceptance rate, network utilization, etc. The BB acts as a Policy Decision Point (PDP) in deciding whether to allow or reject a flow, whilst the edge routers acts as Policy Enforcement Points (PEPs) to police traffic (allowing and marking packets, or simply dropping them).
DiffServ allows two carrier services apart from the default best-effort service: Assured Forwarding (AF) and Expedited Forwarding (EF). AF provides a better-than-best-effort service, but is similar to best-effort traffic in that bursts and packet delay variation (PDV) are to be expected. Out of profile AF packets are given a lower priority by being marked as best effort traffic. EF provides a virtual wire service with traffic shaping to prevent bursts, strict admission control (out of profile packets are dropped) and a separate queue for EF traffic in the core routers, which together keep queues small and avoid the need for buffer management. The resulting EF service is low loss, low delay and low PDV. Hence although loosely a BB allocates bandwidth, really it allocates carr |
https://en.wikipedia.org/wiki/Chimeric%20nuclease | Chimeric nucleases are an example of engineered proteins which must comprise a DNA-binding domain to give sequence specificity and a nuclease domain for DNA cleavage.
DNA-binding domains
DNA-binding domains including the basic helix-loop-helix, zinc finger, helix-turn-helix and leucine zipper motifs have been used in construction of sequence-specific nucleases. Of these, zinc fingers have been suggested the most important due to their modularity, allowing construction of a tailor-made DNA-binding domain.
Nuclease domain
The nuclease domain is responsible for physical cleavage of DNA strands and may introduce either single stranded or double-stranded breaks. FokI is an example of a sequence-specific endonuclease whose non-specific nuclease domain introduces double stranded breaks and has been used in a variety of experiments including identification of high- and low-affinity binding sites of transcription factors in vitro, to study recruitment of factors to promoter sites in vivo using protein position identification with a nuclease tail assay and to study proteins specific to interaction with DNA in the Z-DNA conformation (Durai et al., 2005 and references therein).
See also
Protein engineering
Chimera (protein) |
https://en.wikipedia.org/wiki/E-carrier | The E-carrier is a member of the series of carrier systems developed for digital transmission of many simultaneous telephone calls by time-division multiplexing. The European Conference of Postal and Telecommunications Administrations (CEPT) originally standardised the E-carrier system, which revised and improved the earlier American T-carrier technology, and this has now been adopted by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T). It was widely used in almost all countries outside the US, Canada, and Japan. E-carrier deployments have steadily been replaced by Ethernet as telecommunication networks transition towards all IP.
E1 frame structure
An E1 link operates over two separate sets of wires, usually unshielded twisted pair (balanced cable) or using coaxial (unbalanced cable). A nominal 3 volt peak signal is encoded with pulses using a method avoiding long periods without polarity changes. The line data rate is 2.048 Mbit/s (full duplex, i.e. 2.048 Mbit/s downstream and 2.048 Mbit/s upstream) which is split into 32 timeslots, each being allocated 8 bits in turn. Thus each timeslot sends and receives an 8-bit PCM sample, usually encoded according to A-law algorithm, 8,000 times per second (8 × 8,000 × 32 = 2,048,000). This is ideal for voice telephone calls where the voice is sampled at that data rate and reconstructed at the other end. The timeslots are numbered from 0 to 31.
Special timeslots
One timeslot (TS0) is reserved for framing purposes, and alternately transmits a fixed pattern. This allows the receiver to lock onto the start of each frame and match up each channel in turn. The standards allow for a full cyclic redundancy check to be performed across all bits transmitted in each frame, to detect if the circuit is losing bits (information), but this is not always used. An alarm signal may also be transmitted using timeslot TS0. Finally, some bits are reserved for national use.
One timeslot (TS16) is often |
https://en.wikipedia.org/wiki/Sakhr%20Software%20Company | Sakhr Software Company () is an Arabic language technology company based in Kuwait. It deals with products for the Middle East in e-governance, education, wireless, and security. Sakhr was founded in 1982 by Mohammed AlSharekh.
The Company currently has 200 employees worldwide. Its research and engineering activities are in Silicon Valley and Egypt, with sales offices in the United States (Washington, DC and California), Kuwait, UAE (Dubai and Abu Dhabi), Oman, Egypt and Saudi Arabia.
History
Sakhr was founded in 1982 by Mohammed AlSharekh.
In 1990, following the first events of the Gulf War, Sakhr relocated to Heliopolis, Cairo. After the relocation, the company changed its approach by terminating all computer manufacturing projects to focus exclusively on developing software products.
Sakhr provided Arabic language localization services to the Saudi's Ministry of Education, Egypt's Ministry of Commerce, Oman's Ministry of Education, and the Dubai Chamber of Commerce and Industry.
Dial Directions
In 2009, Sakhr acquired Dial Directions, Inc., a United States Silicon Valley software company providing language applications for mobile cloud-computing environments, including wireless carriers, telematics, and “smartphones” such as the Apple iPhone to enhance its market position in the emerging mobile application & cloud computing market.
Awards
Sakhr software has won the following International awards:
eContent Award – Arabic Language Buddy for smart phones (2010)
Oman Portal – Arab Web Awards (2010)
World Summit Award – (Screen reader for the blind) (2007)
World Summit Award – Best e-content (Web Content Translation Engine – Tarjim) (2005)
Arabian Business E-Achievement Award E-Visionary of the Year (2002)
Internet Shopper (T4S International Group): Best Arabic Language Supported Site (GITEX Cairo 2000)
Damtex Middle East Group: Best Arabic Application Development Company (1999)
See also
Sakhr Computers
Arabic machine translation |
https://en.wikipedia.org/wiki/IMelody | iMelody is a non-polyphonic ringtone exchange object format, used for mobile phones [Extension: .imy], defined by Ericsson and Sony Ericsson together with other manufacturers and is based on Ericsson's proprietary eMelody format. This ringtone format also supports codes that can control the vibration motor, backlight, LED lights and volume of the device. The iMelody format was made because the eMelody had some musical limitations.
Transferring melody to mobile phones
In order to transfer these ringtones to a mobile phone, one can simply send an SMS message with the iMelody/eMelody text as the text of the message, or make a plain text file containing the iMelody/eMelody text, using the extension of either .imy for iMelody or .emy for eMelody, and transfer the file to the mobile phone by Bluetooth, IrDA (infrared), or by a data cable. The file could also be attached to an MMS message or an e-mail message.
iMelody
MIME: "text/x-iMelody" or "audio/iMelody"
Extension: ".imy"
Here is an example of an advanced ringtone in the iMelody format, this is a silent ringtone that only makes the phone's vibrating motor vibrate constantly:
BEGIN:IMELODY
VERSION:1.2
FORMAT:CLASS1.0
BEAT:25
MELODY:vibeonr2vibeonr2vibeon (r2vibeonvibeonr2vibeonr2vibeonr2vibeonr2vibeonr2vibeonr2vibeonr2vibeonr2vibeonr2vibeonr2vibeonr2vibeonr2vibeonr2vibeonr2vibeonr2vibeonr2ledonr2vibeonr2vibeon
END:IMELODY
Another example of an advanced ringtone, which makes the vibrating motor vibrate constantly, the backlight of the phone's display blink and plays a simple tone:
BEGIN:IMELODY
VERSION:1.2
FORMAT:CLASS1.0
BEAT:900
STYLE:S1
MELODY:(vibeonbackoff*6c5ledon*6d5ledoff*6e5ledon*6f5ledoff*6g5ledon*6a5ledoff*6b5ledon*6a5ledoff*6g5*6f5*6e5*6d5*6c5backon*6d5*6e5*6f5*6g5*6a5*6b5*6a5*6g5*6f5*6e5*6d5@0)
END:IMELODY
eMelody
MIME: "text/x-eMelody" or "audio/e-melody"
Extension: ".emy"
Here is an example of a ringtone in eMelody format:
BEGIN:EMELODY
VERSION:1.0
NAME:Test melody 1
COMPOSER: |
https://en.wikipedia.org/wiki/Complete%20sequence | In mathematics, a sequence of natural numbers is called a complete sequence if every positive integer can be expressed as a sum of values in the sequence, using each value at most once.
For example, the sequence of powers of two (1, 2, 4, 8, ...), the basis of the binary numeral system, is a complete sequence; given any natural number, we can choose the values corresponding to the 1 bits in its binary representation and sum them to obtain that number (e.g. 37 = 1001012 = 1 + 4 + 32). This sequence is minimal, since no value can be removed from it without making some natural numbers impossible to represent. Simple examples of sequences that are not complete include the even numbers, since adding even numbers produces only even numbers—no odd number can be formed.
Conditions for completeness
Without loss of generality, assume the sequence an is in non-decreasing order, and define the partial sums of an as:
.
Then the conditions
are both necessary and sufficient for an to be a complete sequence.
A corollary to the above states that
are sufficient for an to be a complete sequence.
However there are complete sequences that do not satisfy this corollary, for example , consisting of the number 1 and the first prime after each power of 2.
Other complete sequences
The complete sequences include:
The sequence of the number 1 followed by the prime numbers (studied by S. S. Pillai and others); this follows from Bertrand's postulate.
The sequence of practical numbers which has 1 as the first term and contains all other powers of 2 as a subset.
The Fibonacci numbers, as well as the Fibonacci numbers with any one number removed. This follows from the identity that the sum of the first n Fibonacci numbers is the (n + 2)nd Fibonacci number minus 1.
Applications
Just as the powers of two form a complete sequence due to the binary numeral system, in fact any complete sequence can be used to encode integers as bit strings. The rightmost bit position is assigned to t |
https://en.wikipedia.org/wiki/National%20Centre%20for%20Food%20Manufacturing | The National Centre for Food Manufacturing (NCFM) is the food science campus of the University of Lincoln, situated on Park Road at Holbeach in the south of the county of Lincolnshire. It offers part-time apprenticeships and distance learning degrees for individuals working in the food industry.
Apprenticeships, Degree and Foundation Courses
The National Centre for Food Manufacturing offers part time distance learning options to achieve Foundation and BSc (Honours) Food Manufacture degrees and higher degrees through research together with all levels of apprenticeships including Higher Apprenticeships (which includes a Foundation Degree). The Foundation and Undergraduate degrees cover areas including Food and Drink Operations and Manufacturing Management - Food Science and Technology – and Food Supply Chain Management. The Centre also offers part time Masters and PhDs - often progressed by food sector employees and focused on specific Food Manufacturing Industry Challenges.
The Higher and Degree Apprenticeships include the CMDA (Chartered Manager Degree Apprenticeship), Departmental Manager, Laboratory Scientist and Professional Technical degrees.
The Centre provides support to apprentices for Functional Skills development in maths and English as required by their relevant apprenticeship standard and offers employers a complete skills development programme for its employees.
NCFM has apprenticeship partnerships with 250 UK food businesses including Addo Food Group, Bakkavor, Bidfood, Dalehead Foods, Summers Butchery Services, Greencore Group, Tulip, Dovecote Park, Fresttime, Finlays, JDM Food Group, Kerry, Nestle, Worldwide Fruit, University Academy Holbeach, Produce World Group, J.O. Sims Ltd, Greenvale AP, FreshLinc, Ripe Now and Lincolshire Field Products.
Research
NCFM advances food manufacturing and related food supply chain research initiatives via a wide range of industry and academic partnerships. The areas of core research include Robotics and Automatio |
https://en.wikipedia.org/wiki/Van%20der%20Waals%20equation | In chemistry and thermodynamics, the Van der Waals equation (or Van der Waals equation of state) is an equation of state which extends the ideal gas law to include the effects of interaction between molecules of a gas, as well as accounting for the finite size of the molecules.
The ideal gas law treats gas molecules as point particles that interact with their containers but not each other, meaning they neither take up space nor change kinetic energy during collisions (i.e. all collisions are perfectly elastic). The ideal gas law states that the volume V occupied by n moles of any gas has a pressure P at temperature T given by the following relationship, where R is the gas constant:
To account for the volume occupied by real gas molecules, the Van der Waals equation replaces in the ideal gas law with , where Vm is the molar volume of the gas and b is the volume occupied by the molecules of one mole, given by Avogadro constant times the volume of a single molecule:
The second modification made to the ideal gas law accounts for interaction between molecules of the gas. The Van der Waals equation includes intermolecular interaction by adding to the observed pressure P in the equation of state a term of the form , where a is a constant whose value depends on the gas.
The complete Van der Waals equation is therefore:
For n moles of gas, it can also be written as:
When the molar volume Vm is large, b becomes negligible in comparison with Vm, a/Vm2 becomes negligible with respect to P, and the Van der Waals equation reduces to the ideal gas law, PVm=RT.
This equation approximates the behavior of real fluids above their critical temperatures and is qualitatively reasonable for their liquid and low-pressure gaseous states at low temperatures. However, near the phase transitions between gas and liquid, in the range of p, V, and T where the liquid phase and the gas phase are in equilibrium, the Van der Waals equation fails to accurately model observed experimental beha |
https://en.wikipedia.org/wiki/Eparterial%20bronchus | The eparterial bronchus (right superior lobar bronchus) is a branch of the right main bronchus given off about 2.5 cm from the bifurcation of the trachea. This branch supplies the superior lobe of the right lung and is the most superior of all secondary bronchi. It arises above the level of the right pulmonary artery, and for this reason is named the eparterial bronchus. All other distributions falling below the pulmonary artery are termed hyparterial.
The eparterial bronchus is the only secondary bronchus with a specific name apart from the name of its corresponding lobe.
Name
The classification of eparterial and hyparterial is attributed to Swiss anatomist and anthropologist Christoph Theodor Aeby, and is central to his model of the anatomical lung. He presented this model in a monograph titled, "Der Bronchialbaum der Säugethiere und des Menschen, nebst Bemerkungen über den Bronchialbaum der Vögel und Reptilien". |
https://en.wikipedia.org/wiki/Bephenium%20hydroxynaphthoate | Bephenium hydroxynaphthoate (INN, trade names Alcopara, Alcopar, Befenium, Debefenium, Francin, Nemex) is an anthelmintic agent formerly used in the treatment of hookworm infections and ascariasis. It is formulated as a salt between the active pharmaceutical ingredient, bephenium, and 3-hydroxy-2-naphthoic acid.
Bephenium is not FDA-approved and is not available in the United States. |
https://en.wikipedia.org/wiki/Aphanizomenon%20flos-aquae | Aphanizomenon flos-aquae is a brackish and freshwater species of cyanobacteria found around the world, including the Baltic Sea and the Great Lakes.
Ecology
Aphanizomenon flos-aquae can form dense surface aggregations in freshwater (known as "cyanobacterial blooms"). These blooms occur in areas of high nutrient loading, historical or current.
Toxicity
Aphanizomenon flos-aquae has both toxic and nontoxic forms. Most sources worldwide are toxic, containing both hepatic and neuroendotoxins.
Most cyanobacteria (including Aphanizomenon) produce BMAA, a neurotoxin amino acid implicated in ALS/Parkinsonism.
Toxicity of A. flos-aquae has been reported in Canada, Germany and China.
Aphanizomenon flos-aquae is known to produce endotoxins, the toxic chemicals released when cells die. Once released (lysed), and ingested, these toxins can damage liver and nerve tissues in mammals. In areas where water quality is not closely monitored, the World Health Organization has assessed toxic algae as a health risk, citing the production of anatoxin-a, saxitoxins, and cylindrospermopsin. Dogs have been reported to have become ill or have fatal reactions after swimming in rivers and lakes containing toxic A. flos-aquae.
Microcystin toxin has been found in all 16 samples of A. flos-aquae products sold as food supplements in Germany and Switzerland, originating from Lake Klamath: 10 of 16 samples exceeded the safety value of 1 μg microcystin per gram. University professor Daniel Dietrich warned parents not to let children consume A. flos-aquae products, since children are even more vulnerable to toxic effects, due to lower body weight, and the continuous intake might lead to accumulation of toxins. Dietrich also warned against quackery schemes selling these cyanobacteria as medicine against illnesses such as attention deficit hyperactivity disorder, causing people to omit their regular drugs.
Medical research
A Canadian study studying the effect of A. flos-aquae on the immune and en |
https://en.wikipedia.org/wiki/Remdesivir | Remdesivir, sold under the brand name Veklury, is a broad-spectrum antiviral medication developed by the biopharmaceutical company Gilead Sciences. It is administered via injection into a vein. During the COVID19 pandemic, remdesivir was approved or authorized for emergency use to treat COVID19 in numerous countries.
Remdesivir was originally developed to treat hepatitis C, and was subsequently investigated for Ebola virus disease and Marburg virus infections before being studied as a post-infection treatment for COVID19.
Remdesivir is a prodrug that is intended to allow intracellular delivery of GS-441524 monophosphate and subsequent biotransformation into GS-441524 triphosphate, a ribonucleotide analogue inhibitor of viral RNA polymerase.
The most common side effect in healthy volunteers is raised blood levels of liver enzymes. The most common side effect in people with COVID19 is nausea. Side effects may include liver inflammation and an infusion-related reaction with nausea, low blood pressure, and sweating.
The U.S. Food and Drug Administration (FDA) considers it to be a first-in-class medication.
Medical uses
In the European Union, remdesivir is indicated for the treatment of coronavirus disease 2019 (COVID19) in adults and adolescents (aged twelve years and older with body weight at least ) with pneumonia requiring supplemental oxygen and for adults who do not require supplemental oxygen and who are at increased risk of progressing to severe COVID19.
In the United States, remdesivir is indicated for the treatment of COVID19 in people 28 days of age and older and weighing at least who are hospitalized; or not hospitalized and have mild-to-moderate COVID19, and are at high risk for progression to severe COVID19, including hospitalization or death.
In November 2020, the FDA issued an emergency use authorization (EUA) for the combination of baricitinib with remdesivir, for the treatment of suspected or laboratory confirmed COVID19 in hospitalized people |
https://en.wikipedia.org/wiki/Coulomb%20damping | Coulomb damping is a type of constant mechanical damping in which the system's kinetic energy is absorbed via sliding friction (the friction generated by the relative motion of two surfaces that press against each other). Coulomb damping is a common damping mechanism that occurs in machinery.
History
Coulomb damping was so named because Charles-Augustin de Coulomb carried on research in mechanics. He later published a work on friction in 1781 entitled "Theory of Simple Machines" for an Academy of Sciences contest. Coulomb then gained much fame for his work with electricity and magnetism.
Modes of Coulombian friction
Coulomb damping absorbs energy with friction, which converts that kinetic energy into thermal energy, i.e. heat. Coulomb friction considers this under two distinct modes: either static, or kinetic.
Static friction occurs when two objects are not in relative motion, e.g. if both are stationary. The force exerted between the objects does exceed—in magnitude—the product of the normal force and the coefficient of static friction :
.
Kinetic friction on the other hand, occurs when two objects are undergoing relative motion, as they slide against each other. The force exerted between the moving objects is equal in magnitude to the product of the normal force and the coefficient of kinetic friction :
.
Regardless of the mode, friction always acts to oppose the objects' relative motion. The normal force is taken perpendicularly to the direction of relative motion; under the influence of gravity, and in the common case of an object supported by a horizontal surface, the normal force is just the weight of the object itself.
As there is no relative motion under static friction, no work is done, and hence no energy can be dissipated. An oscillating system is (by definition) only dampened via kinetic friction.
Illustration
Consider a block of mass that slides over a rough horizontal surface under the restraint of a spring with a spring constant . The s |
https://en.wikipedia.org/wiki/Quasirandom%20group | In mathematics, a quasirandom group is a group that does not contain a large product-free subset. Such groups are precisely those without a small non-trivial irreducible representation. The namesake of these groups stems from their connection to graph theory: bipartite Cayley graphs over any subset of a quasirandom group are always bipartite quasirandom graphs.
Motivation
The notion of quasirandom groups arises when considering subsets of groups for which no two elements in the subset have a product in the subset; such subsets are termed product-free. László Babai and Vera Sós asked about the existence of a constant for which every finite group with order has a product-free subset with size at least . A well-known result of Paul Erdős about sum-free sets of integers can be used to prove that suffices for abelian groups, but it turns out that such a constant does not exist for non-abelian groups.
Both non-trivial lower and upper bounds are now known for the size of the largest product-free subset of a group with order . A lower bound of can be proved by taking a large subset of a union of sufficiently many cosets, and an upper bound of is given by considering the projective special linear group for any prime . In the process of proving the upper bound, Timothy Gowers defined the notion of a quasirandom group to encapsulate the product-free condition and proved equivalences involving quasirandomness in graph theory.
Graph quasirandomness
Formally, it does not make sense to talk about whether or not a single group is quasirandom. The strict definition of quasirandomness will apply to sequences of groups, but first bipartite graph quasirandomness must be defined. The motivation for considering sequences of groups stems from its connections with graphons, which are defined as limits of graphs in a certain sense.
Fix a real number A sequence of bipartite graphs (here is allowed to skip integers as long as tends to infinity) with having vertices, vert |
https://en.wikipedia.org/wiki/FERMIAC | The Monte Carlo trolley, or FERMIAC, was an analog computer invented by physicist Enrico Fermi to aid in his studies of neutron transport.
Operation
The FERMIAC employed the Monte Carlo method to model neutron transport in various types of nuclear systems. Given an initial distribution of neutrons, the goal of the process is to develop numerous "neutron genealogies", or models of the behavior of individual neutrons, including each collision, scattering, and fission. When a fission occurs, the number of emerging neutrons is predicted, and the behavior of each of these neutrons is eventually modeled in the same manner as the first. At each stage, pseudo-random numbers are used to make decisions that affect the behavior of each neutron.
The FERMIAC used this method to create two-dimensional neutron genealogies on a scale diagram of a nuclear device. A series of drums on the device were set according to the material being crossed and a random choice between fast and slow neutrons. Random numbers also determined the direction of travel and the distance until the next collision. Once the drums were set, the trolley was rolled across the diagram, drawing a path as it went. Any time a change in material was indicated on the diagram, the drum settings were adjusted accordingly before continuing.
History
In the early 1930s, Italian physicist Enrico Fermi led a team of young scientists, dubbed the "Via Panisperna boys", in their now-famous experiments in nuclear physics. During this time, Fermi developed "statistical sampling" techniques that he effectively employed to predict the results of experiments.
Years later, in 1946, Fermi participated in the initial review of results from the ENIAC. Among the others present was Los Alamos mathematician Stanislaw Ulam, who was familiar with the use of statistical sampling techniques similar to those previously developed by Fermi. Such techniques had mainly fallen out of use, due to the long, repetitious calculations requ |
https://en.wikipedia.org/wiki/Inferior%20parietal%20lobule | The inferior parietal lobule (subparietal district) lies below the horizontal portion of the intraparietal sulcus, and behind the lower part of the postcentral sulcus. Also known as Geschwind's territory after Norman Geschwind, an American neurologist, who in the early 1960s recognised its importance. It is a part of the parietal lobe.
Structure
It is divided from rostral to caudal into two gyri:
One, the supramarginal gyrus (BA 40), arches over the upturned end of the lateral fissure; it is continuous in front with the postcentral gyrus, and behind with the superior temporal gyrus.
The second, the angular gyrus (BA 39), arches over the posterior end of the superior temporal sulcus, behind which it is continuous with the middle temporal gyrus.
In males, the inferior parietal lobule is significantly more voluminous in the left hemisphere compared to the right. This extreme asymmetry is not present in females, and may contribute to slight cognitive variations of both sexes.
In macaque neuroanatomy, this region is often divided into caudal and rostral portions, cIPL and rIPL, respectively. The cIPL is further divided into areas Opt and PG whereas rIPL is divided into PFG and PF areas.
Function
Inferior parietal lobule has been involved in the perception of emotions in facial stimuli, and interpretation of sensory information. The Inferior parietal lobule is concerned with language, mathematical operations, and body image, particularly the supramarginal gyrus and the angular gyrus.
Clinical significance
Destruction to the inferior parietal lobule of the dominant hemisphere results in Gerstmann's syndrome: right-to-left confusion, finger agnosia, dysgraphia and dyslexia, dyscalculia, contralateral hemianopia, or lower quadrantanopia. Destruction to the inferior parietal lobule of the non-dominant hemisphere results in topographic memory loss, anosognosia, construction apraxia, dressing apraxia, contralateral sensory neglect, contralateral hemianopia, or lower quadr |
https://en.wikipedia.org/wiki/Cotriple%20homology | In algebra, given a category C with a cotriple, the n-th cotriple homology of an object X in C with coefficients in a functor E is the n-th homotopy group of the E of the augmented simplicial object induced from X by the cotriple. The term "homology" is because in the abelian case, by the Dold–Kan correspondence, the homotopy groups are the homology of the corresponding chain complex.
Example: Let N be a left module over a ring R and let . Let F be the left adjoint of the forgetful functor from the category of rings to Set; i.e., free module functor. Then defines a cotriple and the n-th cotriple homology of is the n-th left derived functor of E evaluated at M; i.e., .
Example (algebraic K-theory): Let us write GL for the functor . As before, defines a cotriple on the category of rings with F free ring functor and U forgetful. For a ring R, one has:
where on the left is the n-th K-group of R. This example is an instance of nonabelian homological algebra.
Notes |
https://en.wikipedia.org/wiki/India%20Stack | India Stack refers to the project of creating a unified software platform to bring India's population into the digital age. Its website describes its mission as follows: "India Stack is a set of open APIs that allows governments, businesses, startups and developers to utilize a unique digital Infrastructure to solve India’s hard problems towards presence-less, paperless, and cashless service delivery" Of the four "distinct technology layers" mentioned on the same page, the first, the "Presenceless Layer" is the most controversial as it involves storing biometric data such as fingerprints for every citizen. Since such markers are widely being adopted to enable cashless payment, the issue arises of fraudulent use of biometrics. The other layers are the Paperless Layer, which enables personal records to be associated with one's online identity; the Cashless Layer, a single interface to all national banks and online wallets; and the Consent Layer, which aims to maintain security and control of personal data.
India Stack is the largest open API in the world. Since its deployment, India has been organizing hackathons to develop applications for the APIs.
India Stack is being implemented in stages, starting with the introduction in 2009 of the Aadhaar "Universal ID" numbers. These are linked to biometrics (fingerprints) and as time goes by, authentication by Aadhaar is required for access to more and more services and subsidies. This raises issues of privacy and surveillance, especially as much of the users' interface is via their mobile phones.
The next stages were the introduction of eKYC (electronic Know Your Customer), which enables paperless and rapid verification of address, identity etc., followed by eSign, whereby users attach a legally valid electronic signature to a document, and Unified Payments Interface (UPI) enabling cashless payments, and most recently, DigiLocker, a platform for issuance and verification of documents and certificates.
What raised the pr |
https://en.wikipedia.org/wiki/Phytoglobin-NO%20cycle | The phytoglobin-nitric oxide cycle is a metabolic pathway induced in plants under hypoxic conditions which involves nitric oxide (NO) and phytoglobin (Pgb). It provides an alternative type of respiration to mitochondrial electron transport under the conditions of limited oxygen supply. Phytoglobin in hypoxic plants acts as part of a soluble terminal nitric oxide dioxygenase system, yielding nitrate ion from the reaction of oxygenated phytoglobin with NO. Class 1 phytoglobins are induced in plants under hypoxia, bind oxygen very tightly at nanomolar concentrations, and can effectively scavenge NO at oxygen levels far below the saturation of cytochrome c oxidase. In the course of the reaction, phytoglobin is oxidized to metphytoglobin which has to be reduced for continuous operation of the cycle. Nitrate is reduced to nitrite by nitrate reductase, while NO is mainly formed due to anaerobic reduction of nitrite which may take place in mitochondria by complex III and complex IV in the absence of oxygen, in the side reaction of nitrate reductase, or by electron transport proteins on the plasma membrane. The overall reaction sequence of the cycle consumes NADH and can contribute to the maintenance of ATP level in highly hypoxic conditions. |
https://en.wikipedia.org/wiki/The%20Key%20%28short%20story%29 | The Key is a science fiction mystery novelette by American writer Isaac Asimov. It is one of the stories featuring the reclusive scientist Wendell Urth. It first appeared in The Magazine of Fantasy & Science Fiction in October 1966, and was reprinted in the anthologies Asimov's Mysteries (1968) and The Best Mysteries of Isaac Asimov (1986).
Plot summary
In this short story, somewhere on the Moon is hidden an extraterrestrial artifact. Two explorers, Jennings and Strauss, discovered it, but Jennings is dead and Strauss is insane. The artifact seems to be able to amplify and transmit thoughts, even to the extent of allowing one person to damage the mind of another. The only clues are a piece of paper with cryptic symbols, numbers, and letters written on it, and the babblings of the remaining member of the expedition, Strauss. Strauss is a member of the Ultras, a eugenicist society dedicated to eliminating "non-essential" people, reducing the human population to a few million who think like themselves. It is feared that the device could enable the Ultras to carry out their plan. The original paper has already disappeared, presumably stolen by an Ultra, and the investigators have only a copy to work with. The clues on the piece of paper seem to point to different locations on the Moon, but one stands out: a vertical arrow pointing upwards to the astrological symbol for Earth. One of the investigators realizes that the message means "go to Earth", or more exactly, "go to Urth". Jennings was a former student of the extraterrologist Wendell Urth. He died of a stab wound from Strauss, but not before rendering Strauss insane using the power of the artifact, and then going to some unknown place to hide it. The mysterious paper was found inside a spacesuit gauntlet.
When the investigators contact Wendell Urth, he recalls Jennings was a man who liked bad puns. Urth professes to enjoy a good pun, but found Jennings' efforts irritating. Reading the paper clue and listening to |
https://en.wikipedia.org/wiki/Harold%20Chestnut | Harold (Hall) Chestnut (November 25, 1917 – August 29, 2001) was an American electrical engineer, control engineer and manager at General Electric and author, who helped establish the fields of control theory and systems engineering.
Biography
Born in Albany, New York, where his father, educated as a civil engineer, worked in the family candy business. Chestnut was raised in the 1920s and went on a scholarship to MIT in 1934 to study chemical engineering. In the first year he was awarded for his outstanding performance in chemistry, but switched anyway to electrical engineering and became co-op student. After five years of study he received a combined B.S. and M.S. degree in electrical engineering in 1940. Chestnut received further on-the-job training in General Electric's Advanced Engineering Program (AEP). Later in his career he received two honorary doctorates in engineering in 1966 from Case Institute of Technology in 1972 from Villanova University.
In 1940 Chestnut began a lifelong career with the General Electric, which would last until his retirement in 1983. He married his wife Erma Ruth Callaway Chestnut in 1944 and they had three sons. During the Second World War Chestnut was both a student and an instructor in General Electric's well-known Advanced Engineering Program. He worked on the design of the central fire-control system and remotely controlled gun turrets used on the B-29 aircraft.
Later he worked in the Aeronautics and Ordnance Department and the Systems Engineering and Analysis branch of the Advanced Technology Laboratory, where he served as manager from 1956 to 1972. Here he worked on a wide variety of technical problems including reliability issues in rapid transit and the Apollo mission to the moon. Later in his career he returned to the field of electric power. This time the focus was power systems automation.
From 1957 to 1959 he was the first president of the International Federation of Automatic Control (IFAC). After his term as presid |
https://en.wikipedia.org/wiki/Kharitonov%27s%20theorem | Kharitonov's theorem is a result used in control theory to assess the stability of a dynamical system when the physical parameters of the system are not known precisely. When the coefficients of the characteristic polynomial are known, the Routh–Hurwitz stability criterion can be used to check if the system is stable (i.e. if all roots have negative real parts). Kharitonov's theorem can be used in the case where the coefficients are only known to be within specified ranges. It provides a test of stability for a so-called interval polynomial, while Routh–Hurwitz is concerned with an ordinary polynomial.
Definition
An interval polynomial is the family of all polynomials
where each coefficient can take any value in the specified intervals
It is also assumed that the leading coefficient cannot be zero: .
Theorem
An interval polynomial is stable (i.e. all members of the family are stable) if and only if the four so-called Kharitonov polynomials
are stable.
What is somewhat surprising about Kharitonov's result is that although in principle we are testing an infinite number of polynomials for stability, in fact we need to test only four. This we can do using Routh–Hurwitz or any other method. So it only takes four times more work to be informed about the stability of an interval polynomial than it takes to test one ordinary polynomial for stability.
Kharitonov's theorem is useful in the field of robust control, which seeks to design systems that will work well despite uncertainties in component behavior due to measurement errors, changes in operating conditions, equipment wear and so on. |
https://en.wikipedia.org/wiki/Pure%20homopolar%20generator | A pure homopolar generator (PHG)
is an electric generator not requiring brushes or electronics or semiconductor parts to convert torque into direct current. In other words, this homopolar generator only requires theoretical homogeneous or actual (constantly or cyclically) homogenized magnetic field to be able to produce direct current. The theory of PHG is explained using Maxwell's equations. This term unifies all devices that work in line with this definition. PHG can be represented by patents, which should also work the other way round: US5977684 (A), PV2011-293 (CZ) application number 2011-293, AU5801890 (A).
Another group of patents with a superconductor shield or shield made of so far unknown material (low-voltage semiconductor with high current permeability or material that excludes magnetic field under normal temperatures): US5144179 (A), DE102012022152 (A1), CN1671030 (A)
See also
Pure homopolar motor
General
Rotating magnetic field brushless motors with electronics |
https://en.wikipedia.org/wiki/Pangamic%20acid | Pangamic acid, also called pangamate, is the name given to a chemical compound discovered by Ernst T. Krebs Sr. His son, Ernst T. Krebs Jr., promoted it as a medicinal compound for use in treatment of a wide range of diseases. They also termed this chemical "Vitamin B15", though it is not a true vitamin, has no nutritional value , has no known use in the treatment of any disease and has been called a "quack remedy". Although a number of compounds labelled "pangamic acid" have been studied or sold (including the 1951 d-gluconodimethylamino acetic acid), no chemical compound, including those claimed by the Krebses to be pangamic acid, has been scientifically verified to have the characteristics that defined the original description of the compound.
The Krebses derived the term "pangamic" to describe this compound which they asserted to be ubiquitous and highly concentrated in seeds (pan meaning "universal" and gamic meaning "seed").
Chemistry
Pangamic acid is the name given to the chemical compound with the empirical formula C10H19O8N and a molecular weight of 281 which appeared to be an ester derived from d-gluconic acid and dimethylglycine. In 1943, the Krebses applied for a patent for a process for extracting this chemical compound which they reported had been previously isolated from apricot seeds, and received the patent in 1949 (US2464240). A 1951 paper by the Krebses (PMID 14840945) reported the first isolation of this compound using this patented process, but did not include enough information to confirm that this compound was actually isolated. In 1955, the Krebses received a patent for another synthesizing process for "N-substituted glycine esters of gluconic acid" (US2710876), but the patent contained no supporting data to confirm the process was able to synthesize compounds described by the patent, including pangamic acid.
Subsequent attempts at synthesizing this ester by other researchers found Krebs' purported methods of producing pangamic acid w |
https://en.wikipedia.org/wiki/Culturally%20Authentic%20Pictorial%20Lexicon | The Culturally Authentic Pictorial Lexicon is a dictionary database of images of various objects in a culturally authentic setting for language learning. All images are presented with a Creative Commons Attribution-NonCommercial-ShareAlike license, allowing for broad academic use by language teachers. The database is also useful for researchers in the field of applied linguistics, visual cognition, and automated image recognition. The database averages 30,000 hits per month and has been incorporated into the curricula of many college and high-school level German teachers.
The idea for the lexicon is partially based on Shaughnessy's experience with teaching materials that used American-based images and clip art to demonstrate German words and concepts. By presenting objects in their culturally authentic context, the CAPL is designed to prepare students to live in the environment where the language is spoken. The photographic entries are real photographs, not clip art, to force teachers to "teach terms for things that actually occur in everyday German life – instead of American concepts that have no direct European equivalent."
The project was founded in 2003 as a pilot project with over 1,000 unique entries for the German language. The first images were collected by Shaughnessy in Germany and Austria through a grant from W&J College. In 2006, it received a $200,000 appropriation from the U.S. federal government. In 2008, the project was expanded to include more languages thanks to an $85,480 grant from the U.S. Department of Education.
The CAPL was featured in an article in The Chronicle of Higher Education and has been recommended for use by the Goethe Institute, German Academic Exchange Office and the National Capital Language Resource Center. The book The Bilingual Mental Lexicon noted the Culturally Authentic Pictorial Lexicon's value in German language instruction for "naming and sorting activities, and in awareness-raising discussions." |
https://en.wikipedia.org/wiki/Tennis%20ball%20theorem | In geometry, the tennis ball theorem states that any smooth curve on the surface of a sphere that divides the sphere into two equal-area subsets without touching or crossing itself must have at least four inflection points, points at which the curve does not consistently bend to only one side of its tangent line.
The tennis ball theorem was first published under this name by Vladimir Arnold in 1994, and is often attributed to Arnold, but a closely related result appears earlier in a 1968 paper by Beniamino Segre, and the tennis ball theorem itself is a special case of a theorem in a 1977 paper by Joel L. Weiner. The name of the theorem comes from the standard shape of a tennis ball, whose seam forms a curve that meets the conditions of the theorem; the same kind of curve is also used for the seams on baseballs.
The tennis ball theorem can be generalized to any curve that is not contained in a closed hemisphere. A centrally symmetric curve on the sphere must have at least six inflection points. The theorem is analogous to the four-vertex theorem according to which any smooth closed plane curve has at least four points of extreme curvature.
Statement
Precisely, an inflection point of a doubly continuously differentiable () curve on the surface of a sphere is a point with the following property: let be the connected component containing of the intersection of the curve with its tangent great circle at . (For most curves will just be itself, but it could also be an arc of the great circle.) Then, for to be an inflection point, every neighborhood of must contain points of the curve that belong to both of the hemispheres separated by this great circle.
The theorem states that every curve that partitions the sphere into two equal-area components has at least four inflection points in this sense.
Examples
The tennis ball and baseball seams can be modeled mathematically by a curve made of four semicircular arcs, with exactly four inflection points where pairs of t |
https://en.wikipedia.org/wiki/A%20New%20Kind%20of%20Science | A New Kind of Science is a book by Stephen Wolfram, published by his company Wolfram Research under the imprint Wolfram Media in 2002. It contains an empirical and systematic study of computational systems such as cellular automata. Wolfram calls these systems simple programs and argues that the scientific philosophy and methods appropriate for the study of simple programs are relevant to other fields of science.
Contents
Computation and its implications
The thesis of A New Kind of Science (NKS) is twofold: that the nature of computation must be explored experimentally, and that the results of these experiments have great relevance to understanding the physical world.
Simple programs
The basic subject of Wolfram's "new kind of science" is the study of simple abstract rules—essentially, elementary computer programs. In almost any class of a computational system, one very quickly finds instances of great complexity among its simplest cases (after a time series of multiple iterative loops, applying the same simple set of rules on itself, similar to a self-reinforcing cycle using a set of rules). This seems to be true regardless of the components of the system and the details of its setup. Systems explored in the book include, amongst others, cellular automata in one, two, and three dimensions; mobile automata; Turing machines in 1 and 2 dimensions; several varieties of substitution and network systems; recursive functions; nested recursive functions; combinators; tag systems; register machines; reversal-addition. For a program to qualify as simple, there are several requirements:
Its operation can be completely explained by a simple graphical illustration.
It can be completely explained in a few sentences of human language.
It can be implemented in a computer language using just a few lines of code.
The number of its possible variations is small enough so that all of them can be computed.
Generally, simple programs tend to have a very simple abstract framework. |
https://en.wikipedia.org/wiki/Gravitational%20compression | Gravitational compression is a phenomenon in which gravity, acting on the mass of an object, compresses it, reducing its size and increasing the object's density.
At the center of a planet or star, gravitational compression produces heat by the Kelvin–Helmholtz mechanism. This is the mechanism that explains how Jupiter continues to radiate heat produced by its gravitational compression.
The most common reference to gravitational compression is stellar evolution. The Sun and other main-sequence stars are produced by the initial gravitational collapse of a molecular cloud. Assuming the mass of the material is large enough, gravitational compression reduces the size of the core, increasing its temperature until hydrogen fusion can begin. This hydrogen-to-helium fusion reaction releases energy that balances the inward gravitational pressure and the star becomes stable for millions of years. No further gravitational compression occurs until the hydrogen is nearly used up, reducing the thermal pressure of the fusion reaction. At the end of the Sun's life, gravitational compression will turn it into a white dwarf.
At the other end of the scale are massive stars. These stars burn their fuel very quickly, ending their lives as supernovae, after which further gravitational compression will produce either a neutron star or a black hole from the remnants.
For planets and moons, equilibrium is reached when the gravitational compression is balanced by a pressure gradient. This pressure gradient is in the opposite direction due to the strength of the material, at which point gravitational compression ceases. |
https://en.wikipedia.org/wiki/Motilin | Motilin is a 22-amino acid polypeptide hormone in the motilin family that, in humans, is encoded by the MLN gene.
Motilin is secreted by endocrine Mo cells (also referred to as M cells, which are not the same as the M cells, or microfold cells, found in Peyer's patches) that are numerous in crypts of the small intestine, especially in the duodenum and jejunum. It is released into the general circulation in humans at about 100-min intervals during the inter-digestive state and is the most important factor in controlling the inter-digestive migrating contractions; and it also stimulates endogenous release of the endocrine pancreas. Based on amino acid sequence, motilin is unrelated to other hormones. Because of its ability to stimulate gastric activity, it was named "motilin." Apart from in humans, the motilin receptor has been identified in the gastrointestinal tracts of pigs, rats, cows, and cats, and in the central nervous system of rabbits.
Discovery
Motilin was discovered by J.C. Brown when he introduced alkaline solution into duodena of dogs, which caused strong gastric contractions. Brown et al. predicted that alkali could either release stimulus to activate motor activity or prevent the secretion of inhibitory hormone. They isolated a polypeptide as a by-product from purification of secretin on carboxymethyl cellulose. They named this polypeptide "Motilin."
Structure
Motilin has 22 amino acids and molecular weight of 2698 Daltons. In extract from human gut and plasma, there are two basic forms of motilin. The first molecular form is the polypeptide of 22 amino acids. The second form, on the other hand, is larger and contains the same 22 amino acids as the first form but includes an additional carboxyl-terminus end.
The sequences of amino acids of motilin is: Phe-Val-Pro-Ile-Phe-Thr-Tyr-Gly-Glu-Leu-Gln-Arg-Met-Gln-Glu-Lys-Glu-Arg-Asn-Lys-Gly-Gln.
The structure and dynamics of the gastrointestinal peptide hormone motilin have been studied in the presence o |
https://en.wikipedia.org/wiki/Macromolecular%20Crystallographic%20Information%20File | The Macromolecular Crystallographic Information File (mmCIF) also known as PDBx/mmCIF is a standard text file format for representing macromolecular structure data, developed by the International Union of Crystallography (IUCr) and the Protein Data Bank It is an extension of the Crystallographic Information File (CIF), specifically for macromolecular data, such as proteins and nucleic acids, incorporating elements from the PDB file format.
mmCIF is intended as an alternative to the Protein Data Bank (PDB) format and is now the default format used by the Protein Data Bank.
mmCIF was designed to address limitations of the PDB format in terms of capacity and flexibility, especially with the increasing size and complexity of macromolecular structures being determined.
The format is part of the larger Crystallographic Information Framework, a system of exchange protocols based on data dictionaries and relational rules expressible in different machine-readable manifestations, including, but not restricted to, the original Crystallographic Information File and XML.
Example
An example of the mmCIF file format is key-value style is:
_cell.entry_id 4HHB
_cell.length_a 63.150
_cell.length_b 83.590
_cell.length_c 53.800
_cell.angle_alpha 90.00
_cell.angle_beta 99.34
_cell.angle_gamma 90.00
_cell.Z_PDB 4
External links
International Union of Crystallography
wwPDB: mmCIF Resources
PDBx/mmCIF conversion service |
https://en.wikipedia.org/wiki/Erd%C5%91s%E2%80%93Tenenbaum%E2%80%93Ford%20constant | The Erdős–Tenenbaum–Ford constant is a mathematical constant that appears in number theory. Named after mathematicians Paul Erdős, Gérald Tenenbaum, and Kevin Ford, it is defined as
where is the natural logarithm.
Following up on earlier work by Tenenbaum, Ford used this constant in analyzing the number of integers that are at most and that have a divisor in the range .
Multiplication table problem
For each positive integer , let be the number of distinct integers in an multiplication table. In 1960, Erdős studied the asymptotic behavior of and proved that
as . |
https://en.wikipedia.org/wiki/Correlation%20function%20%28statistical%20mechanics%29 | In statistical mechanics, the correlation function is a measure of the order in a system, as characterized by a mathematical correlation function. Correlation functions describe how microscopic variables, such as spin and density, at different positions are related. More specifically, correlation functions quantify how microscopic variables co-vary with one another on average across space and time. A classic example of such spatial correlations is in ferro- and antiferromagnetic materials, where the spins prefer to align parallel and antiparallel with their nearest neighbors, respectively. The spatial correlation between spins in such materials is shown in the figure to the right.
Definitions
The most common definition of a correlation function is the canonical ensemble (thermal) average of the scalar product of two random variables, and , at positions and and times and :
Here the brackets, , indicate the above-mentioned thermal average. It is a matter of convention whether one subtracts the uncorrelated average product of and , from the correlated product, , with the convention differing among fields. The most common uses of correlation functions are when and describe the same variable, such as a spin-spin correlation function, or a particle position-position correlation function in an elemental liquid or a solid (often called a Radial distribution function or a pair correlation function). Correlation functions between the same random variable are autocorrelation functions. However, in statistical mechanics, not all correlation functions are autocorrelation functions. For example, in multicomponent condensed phases, the pair correlation function between different elements is often of interest. Such mixed-element pair correlation functions are an example of cross-correlation functions, as the random variables and represent the average variations in density as a function position for two distinct elements.
Equilibrium equal-time (spatial) correlation f |
https://en.wikipedia.org/wiki/EBONE | EBONE (standing for European Backbone) was a pan-European Internet backbone. It went online in 1992 and was deactivated in July 2002. Some portions of the Ebone were sold to other companies and continue to operate today.
History
Formation
In 1991 a certain number of research network managers, including Frode Greisen, from Denmark, Kees Neggers, director of the Dutch network SURFNet, and Francois Fluckiger at CERN sought to create a European Internet backbone open to publicly-financed academic networks and private commercial networks. The Ebone consortium was established at the RIPE meeting in Geneva in September 1991, and the network went online in 1992 after the initial IP backbone with 256 kbps links was completed. Frode Greisen became the general manager while Peter Löthberg served as de facto architect.
Operation
In 1996 the consortium was transformed into the Ebone Association which again established a private limited company Ebone Inc. based in Denmark. In 1998 the Ebone Association sold 75% of the company to Hermes Europe Railtel, and in 1999 the remaining 25% was bought by Global Telesystems Group Inc. (GTS) which had then acquired Hermes Europe Railtel.
The Ebone backbone increased by a factor of 40,000 in speed over nine years from 256 kbit/s to 10 Gbit/s and the traffic roughly followed, see table below:
In year 2000 Ebone provided international transit for around 100 Internet Service Providers based in most of the European countries.
In 2001 GTS re-branded all its data communications products as Ebone and
Ebone was one of Europe's leading broadband optical and IP network service providers.
Shutdown
In October 2001, KPNQwest acquired Ebone and the Central Europe businesses of GTS and completed their EuroRings network.
Following the Dot com crash and various investigations, KPNQwest declared bankruptcy. In June 2002, it was announced that the Ebone Network Operations Center would be shut down, and the Ebone would be deactivated.
Employees in the |
https://en.wikipedia.org/wiki/Adversarial%20stylometry | Adversarial stylometry is the practice of altering writing style to reduce the potential for stylometry to discover the author's identity or their characteristics. This task is also known as authorship obfuscation or authorship anonymisation. Stylometry poses a significant privacy challenge in its ability to unmask anonymous authors or to link pseudonyms to an author's other identities, which, for example, creates difficulties for whistleblowers, activists, and hoaxers and fraudsters. The privacy risk is expected to grow as machine learning techniques and text corpora develop.
All adversarial stylometry shares the core idea of faithfully paraphrasing the source text so that the meaning is unchanged but the stylistic signals are obscured. Such a faithful paraphrase is an adversarial example for a stylometric classifier. Several broad approaches to this exist, with some overlap: imitation, substituting the author's own style for another's; translation, applying machine translation with the hope that this eliminates characteristic style in the source text; and obfuscation, deliberately modifying a text's style to make it not resemble the author's own.
Manually obscuring style is possible, but laborious; in some circumstances, it is preferable or necessary. Automated tooling, either semi- or fully-automatic, could assist an author. How best to perform the task and the design of such tools is an open research question. While some approaches have been shown to be able to defeat particular stylometric analyses, particularly those that do not account for the potential of adversariality, establishing safety in the face of unknown analyses is an issue. Ensuring the faithfulness of the paraphrase is a critical challenge for automated tools.
It is uncertain if the practice of adversarial stylometry is detectable in itself. Some studies have found that particular methods produced signals in the output text, but a stylometrist who is uncertain of what methods may have been use |
https://en.wikipedia.org/wiki/TL%3BDR | TL;DR or tl;dr, short for "too long; didn't read", is internet slang saying that text being referred to has been ignored because of its length. It is also used to introduce a summary of an online post or news article.
The phrase dates back to at least 2002, and was added to the Oxford Dictionaries Online in 2013.
See also
Abstract
Attention economy
BLUF – bottom line up front
Information overload
Internet culture
Lexicographic information cost
Long-form journalism |
https://en.wikipedia.org/wiki/Darwinius | Darwinius is a genus within the infraorder Adapiformes, a group of basal strepsirrhine primates from the middle Eocene epoch. Its only known species, Darwinius masillae, lived approximately 47 million years ago (Lutetian stage) based on dating of the fossil site.
The only known fossil, called Ida, was discovered in 1983 at the Messel pit, a disused quarry near the village of Messel, about 35 km (22 mi) southeast of Frankfurt, Germany. The fossil, divided into a slab and partial counterslab after the amateur excavation and sold separately, was not reassembled until 2007. The fossil is of a juvenile female, approximately overall length, with the head and body length excluding the tail being about . It is estimated that Ida died at about 80–85% of her projected adult body and limb length.
The genus Darwinius was named in commemoration of the bicentenary of the birth of Charles Darwin, and the species name masillae honors Messel where the specimen was found. The creature appeared superficially similar to a modern lemur.
The authors of the paper describing Darwinius classified it as a member of the primate family Notharctidae, subfamily Cercamoniinae, suggesting that it has the status of a significant transitional form (a "link") between the prosimian and simian ("anthropoid") primate lineages. Others have disagreed with this placement.
Concerns have been raised about the claims made about the fossil's relative importance and the publicising of the fossil before adequate information was available for scrutiny by the academic community. Some of Norway's leading biologists, among them Nils Christian Stenseth, have called the fossil an "exaggerated hoax" and stated that its presentation and popular dissemination "fundamentally violate scientific principles and ethics."
Taxonomy
Franzen et al. (2009) place the genus Darwinius in the subfamily Cercamoniinae of the family Notharctidae within the extinct infraorder Adapiformes of early primates.
Darwinius masillae is th |
https://en.wikipedia.org/wiki/Ecosystem%20health | Ecosystem health is a metaphor used to describe the condition of an ecosystem. Ecosystem condition can vary as a result of fire, flooding, drought, extinctions, invasive species, climate change, mining, fishing, farming or logging, chemical spills, and a host of other reasons. There is no universally accepted benchmark for a healthy ecosystem, rather the apparent health status of an ecosystem can vary depending upon which health metrics are employed in judging it and which societal aspirations are driving the assessment. Advocates of the health metaphor argue for its simplicity as a communication tool. "Policy-makers and the public need simple, understandable concepts like health." Some critics worry that ecosystem health, a "value-laden construct", can be "passed off as science to unsuspecting policy makers and the public." However, this term is often used in portraying the state of ecosystems worldwide and in conservation and management. For example, scientific journals and the UN often use the terms planetary and ecosystem health, such as the recent journal The Lancet Planetary Health.
History of the concept
The health metaphor applied to the environment has been in use at least since the early 1800s and the great American conservationist Aldo Leopold (1887–1948) spoke metaphorically of land health, land sickness, mutilation, and violence when describing land use practices. The term "ecosystem management" has been in use at least since the 1950s. The term "ecosystem health" has become widespread in the ecological literature, as a general metaphor meaning something good, and as an environmental quality goal in field assessments of rivers, lakes, seas, and forests.
Recently however this metaphor has been subject of quantitative formulation using complex systems concepts such as criticality, meaning that a healthy ecosystem is in some sort of balance between adaptability (randomness) and robustness (order) . Nevertheless, the universality of criticality is sti |
https://en.wikipedia.org/wiki/Ancestral%20reconstruction | Ancestral reconstruction (also known as Character Mapping or Character Optimization) is the extrapolation back in time from measured characteristics of individuals (or populations) to their common ancestors. It is an important application of phylogenetics, the reconstruction and study of the evolutionary relationships among individuals, populations or species to their ancestors. In the context of evolutionary biology, ancestral reconstruction can be used to recover different kinds of ancestral character states of organisms that lived millions of years ago. These states include the genetic sequence (ancestral sequence reconstruction), the amino acid sequence of a protein, the composition of a genome (e.g., gene order), a measurable characteristic of an organism (phenotype), and the geographic range of an ancestral population or species (ancestral range reconstruction). This is desirable because it allows us to examine parts of phylogenetic trees corresponding to the distant past, clarifying the evolutionary history of the species in the tree. Since modern genetic sequences are essentially a variation of ancient ones, access to ancient sequences may identify other variations and organisms which could have arisen from those sequences. In addition to genetic sequences, one might attempt to track the changing of one character trait to another, such as fins turning to legs.
Non-biological applications include the reconstruction of the vocabulary or phonemes of ancient languages, and cultural characteristics of ancient societies such as oral traditions or marriage practices.
Ancestral reconstruction relies on a sufficiently realistic statistical model of evolution to accurately recover ancestral states. These models use the genetic information already obtained through methods such as phylogenetics to determine the route that evolution has taken and when evolutionary events occurred. No matter how well the model approximates the actual evolutionary history, however, one's |
https://en.wikipedia.org/wiki/International%20Phytogeographic%20Excursion | The International Phytogeographic Excursions was a series of international meetings in plant geography that significantly contributed to exchange of scientific ideas across national and linguistic barriers and also to the rise of Anglo-American plant ecology. The initiative was taken by the British botanist Arthur Tansley at the International Geographic Congress in Geneva in 1908. Tansley and another early key figure, Henry C. Cowles, were both much-inspired by the new 'ecological plant geography' introduced by Eugenius Warming and its quest for answering why-questions about plant distribution, as opposed to the traditional, merely descriptive 'floristic plant geography'.
The First International Phytogeographic Excursion was held in the British Isles in 1911. It was organized by Arthur Tansley and went through parts of England, Scotland and Ireland.
The participants were:
Eduard Rübel, Switzerland
Carl Schroeter, Switzerland
Oscar Drude, Germany
Paul Graebner, Germany
C.A.M. Lindman, Sweden
G. Claridge Druce, England
Jean Massart, Belgium
C.H. Ostenfeld, Denmark
Frederic Clements, U.S.A.
Henry C. Cowles, U.S.A., who gave a brief report in Science in 1913.
The Second International Phytogeographic Excursion was a travel across North America from July to September 1913. It was hosted by a number of American ecologists led by Henry C. Cowles. The participants were:
Henry C. Cowles, U.S.A.
Frederic Clements, U.S.A.
Edith S. Clements, U.S.A.
Alfred Dachnowsky, U.S.A.
George Fuller, U.S.A.
George E. Nichols, U.S.A.
Willis Linn Jepson, U.S.A.
Heinrich Brockmann-Jerosch, Switzerland
Marie Charlotte Brockmann-Jerosch, Switzerland
Ove Paulsen, Denmark
Carl Skottsberg, Sweden
Eduard Rübel, Switzerland
Karl von Tubeuf, Germany
Carl Schroeter, Switzerland
Theodoor J. Stomps, Netherlands
Arthur Tansley, England
Adolf Engler, Germany
Cecil Crampton, Scotland.
The Third International Phytogeographic Excursion was proposed in 1915, but postponed due to the First World War. It |
https://en.wikipedia.org/wiki/Bile | Bile (from Latin bilis), or gall, is a yellow-green fluid produced by the liver of most vertebrates that aids the digestion of lipids in the small intestine. In humans, bile is primarily composed of water, produced continuously by the liver, and stored and concentrated in the gallbladder. After a human eats, this stored bile is discharged into the first section of their small intestine.
Composition
In the human liver, bile is composed of 97–98% water, 0.7% bile salts, 0.2% bilirubin, 0.51% fats (cholesterol, fatty acids, and lecithin), and 200 meq/L inorganic salts. The two main pigments of bile are bilirubin, which is yellow, and its oxidised form biliverdin, which is green. When mixed, they are responsible for the brown color of feces. About of bile is produced per day in adult human beings.
Function
Bile or gall acts to some extent as a surfactant, helping to emulsify the lipids in food. Bile salt anions are hydrophilic on one side and hydrophobic on the other side; consequently, they tend to aggregate around droplets of lipids (triglycerides and phospholipids) to form micelles, with the hydrophobic sides towards the fat and hydrophilic sides facing outwards. The hydrophilic sides are negatively charged, and this charge prevents fat droplets coated with bile from re-aggregating into larger fat particles. Ordinarily, the micelles in the duodenum have a diameter around 1–50 μm in humans.
The dispersion of food fat into micelles provides a greatly increased surface area for the action of the enzyme pancreatic lipase, which digests the triglycerides, and is able to reach the fatty core through gaps between the bile salts. A triglyceride is broken down into two fatty acids and a monoglyceride, which are absorbed by the villi on the intestine walls. After being transferred across the intestinal membrane, the fatty acids reform into triglycerides (), before being absorbed into the lymphatic system through lacteals. Without bile salts, most of the lipids in food wou |
https://en.wikipedia.org/wiki/Metrics%20%28networking%29 | Router metrics are configuration values used by a router to make routing decisions. A metric is typically one of many fields in a routing table. Router metrics help the router choose the best route among multiple feasible routes to a destination. The route will go in the direction of the gateway with the lowest metric.
A router metric is typically based on information such as path length, bandwidth, load, hop count, path cost, delay, maximum transmission unit (MTU), reliability and communications cost.
Examples
A metric can include:
measuring link utilization (using SNMP)
number of hops (hop count)
speed of the path
packet loss (router congestion/conditions)
Network delay
path reliability
path bandwidth
throughput [SNMP - query routers]
load
Maximum transmission unit (MTU)
administrator configured value
In EIGRP, metrics is represented by an integer from 0 to 4,294,967,295 (The size of a 32-bit integer). In Microsoft Windows XP routing it ranges from 1 to 9999.
A metric can be considered as:
additive - the total cost of a path is the sum of the costs of individual links along the path,
concave - the total cost of a path is the minimum of the costs of individual links along the path,
multiplicative - the total cost of a path is the product of the costs of individual links along the path.
Service level metrics
Router metrics are metrics used by a router to make routing decisions. It is typically one of many fields in a routing table.
Router metrics can contain any number of values that help the router determine the best route among multiple routes to a destination. A router metric typically based on information like path length, bandwidth, load, hop count, path cost, delay, MTU, reliability and communications cost.
See also
Administrative distance, indicates the source of routing table entry and is used in preference to metrics for routing decisions |
https://en.wikipedia.org/wiki/Separable%20state | In quantum mechanics, separable states are multipartite quantum states that can be written as a convex combination of product states. Product states are multipartite quantum states that can be written as a tensor product of states in each space. The physical intuition behind these definitions is that product states have no correlation between the different degrees of freedom, while separable states might have correlations, but all such correlations can be explained as due to a classical random variable, as opposed as being due to entanglement.
In the special case of pure states the definition simplifies: a pure state is separable if and only if it is a product state.
A state is said to be entangled if it is not separable. In general, determining if a state is separable is not straightforward and the problem is classed as NP-hard.
Separability of bipartite systems
Consider first composite states with two degrees of freedom, referred to as bipartite states. By a postulate of quantum mechanics these can be described as vectors in the tensor product space . In this discussion we will focus on the case of the Hilbert spaces and being finite-dimensional.
Pure states
Let and be orthonormal bases for and , respectively. A basis for is then , or in more compact notation . From the very definition of the tensor product, any vector of norm 1, i.e. a pure state of the composite system, can be written as
where is a constant.
If can be written as a simple tensor, that is, in the form with a pure state in the i-th space, it is said to be a product state, and, in particular, separable. Otherwise it is called entangled. Note that, even though the notions of product and separable states coincide for pure states, they do not in the more general case of mixed states.
Pure states are entangled if and only if their partial states are not pure. To see this, write the Schmidt decomposition of as
where are positive real numbers, is the Schmidt rank of , and and |
https://en.wikipedia.org/wiki/ERP%20security | ERP Security is a wide range of measures aimed at protecting Enterprise resource planning (ERP) systems from illicit access ensuring accessibility and integrity of system data. ERP system is a computer software that serves to unify the information intended to manage the organization including Production, Supply Chain Management, Financial Management, Human Resource Management, Customer Relationship Management, Enterprise Performance Management.
Review
ERP system integrates business processes enabling procurement, payment, transport, human resources management, product management, and financial planning.
As ERP system stores confidential information, the Information Systems Audit and Control Association (ISACA) recommends to regularly conduct a comprehensive assessment of ERP system security, checking ERP servers for software vulnerabilities, configuration errors, segregation of duties conflicts, compliance with relevant standards and recommendations, and recommendations of vendors.
Causes for vulnerabilities in ERP systems
Complexity
ERP systems process transactions and implement procedures to ensure that users have different access privileges. There are hundreds of authorization objects in SAP permitting users to perform actions in the system. In case of 200 users of the company, there are approximately 800,000 (100*2*20*200) ways to customize security settings of ERP systems. With the growth of complexity, the possibility of errors and segregation of duties conflicts increases.
Specificity
Vendors fix vulnerabilities on the regular basis since hackers monitor business applications to find and exploit security issues. SAP releases patches monthly on Patch Tuesday, Oracle issues security fixes every quarter in Oracle Critical Patch Update. Business applications are becoming more exposed to the Internet or migrate to the cloud.
Lack of competent specialists
ERP Cybersecurity survey revealed that organizations running ERP systems "lack both awareness and a |
https://en.wikipedia.org/wiki/Temperate%20South%20America | Temperate South America is a biogeographic region of the Earth's seas, comprising the temperate and subtropical waters of South America, including both the Pacific and Atlantic coasts of the continent and adjacent islands. It also includes the remote Gough Island and Tristan da Cunha in the South Atlantic Ocean.
Temperate Southern Africa is a marine realm, one of the great biogeographic divisions of the world's ocean basins.
On the Atlantic coast, Temperate South America transitions to the Tropical Atlantic marine realm near Rio de Janeiro in Brazil. On the Pacific coast, it extends to Punta Aguja in northern Peru, where it transitions to the Tropical Eastern Pacific realm. To the south lies the Southern Ocean.
The Atlantic coast is influenced by the Brazil Current, which carries warm tropical waters south along the coast. On the Pacific coast, the cold Humboldt Current carries cold Antarctic waters north towards the tropics.
Subdivisions
The Temperate South America realm is divided into five marine provinces. The three larger provinces are composed of smaller ecoregions.
Warm Temperate Southeastern Pacific
Central Peru
Humboldtian
Central Chile
Araucanian
Juan Fernandez and Desventuradas
Juan Fernandez Islands and Desventuradas Islands
Despite their geographical proximity to the South American coast, these islands have also been included in the Oceanian realm, due to strong Hawaiian and southeast Polynesian biogeographic influences and the presence of an endemic insect and plant family.
Warm Temperate Southwestern Atlantic
Southeastern Brazil
Rio Grande
Rio de la Plata
Uruguay-Buenos Aires Shelf
Magellanic
North Patagonian Gulfs
Patagonian Shelf
Falkland Islands
Channels and Fjords of Southern Chile
Chiloense
Tristan Gough
Tristan da Cunha and Gough Island |
https://en.wikipedia.org/wiki/Brain%2C%20Behavior%20and%20Evolution | Brain, Behavior and Evolution is a peer-reviewed scientific journal covering evolutionary neurobiology. It was established in 1968 with Walter Riss as the founding editor-in-chief; he remained the editor until 1986. Subsequent editors included Glenn Northcutt (1986–1998) and Walter Wilczynski (1999–2009). The current editor-in-chief is Georg F. Striedter (University of California, Irvine). According to the Journal Citation Reports, the journal has a 2016 impact factor of 1.915. |
https://en.wikipedia.org/wiki/European%20Battery%20Alliance | The European Battery Alliance (EBA) is Europe's plan to create its own competitive and sustainable battery cell manufacturing value chain. Its purpose is to ensure that Europe benefits from the technological evolution in the Electric Vehicle Market and beyond. The action plan includes cleaner and more sustainable vehicles as well as safer traffic operations across Europe.
Stakeholders
120 industrial innovation stakeholders are currently active under the EBA alliance in partnership with participant EU states and the European Investment Bank. This entails growth and investment potential of the battery sector across Europe and beyond.
Operations
The action plan adopted focuses on innovating and developing a sustainable and competitive battery 'ecosystem' within Europe. The primary objective is to create a manufacturing value chain with sustainable battery cells at its core in order to avoid a technological dependence from 3rd parties. According to analysts, by 2025, Europe could capture a €250 billion market. EU wide demand is forecast to demand 10 to 20 large-scale battery cell production facilities. The first planned plant, called the "Automotive Cell Co.", will be stationed at a Groupe PSA’s site in Kaiserslautern. Saft Groupe S.A. will be taking part in the operations as this plant will be complementing another production facility located at Hauts-de-France. The two plants are to be operational by 2024, employ around 2,000 and serve up to 15% of Europe's demand.
Environmental impact
The European Union and all stakeholders involved are considering the entire life-cycle of batteries, including the environmental gains of use and the impact triggered by their production. Recycling and the recovery of materials at the end of the life cycle reduces the impact of both mining and manufacturing. emissions and hazardous substances used are lowered and the impact of mining is reduced. The EU wants to ensure recycling through the Battery Directive to offset the negative |
https://en.wikipedia.org/wiki/Thermoduric%20bacterium | Thermoduric bacteria are bacteria which can survive, to varying extents, the pasteurisation process. Species of bacteria which are thermoduric include Bacillus, Clostridium and Enterococci. |
https://en.wikipedia.org/wiki/Brianchon%27s%20theorem | In geometry, Brianchon's theorem is a theorem stating that when a hexagon is circumscribed around a conic section, its principal diagonals (those connecting opposite vertices) meet in a single point. It is named after Charles Julien Brianchon (1783–1864).
Formal statement
Let be a hexagon formed by six tangent lines of a conic section. Then lines (extended diagonals each connecting opposite vertices) intersect at a single point , the Brianchon point.
Connection to Pascal's theorem
The polar reciprocal and projective dual of this theorem give Pascal's theorem.
Degenerations
As for Pascal's theorem there exist degenerations for Brianchon's theorem, too: Let coincide two neighbored tangents. Their point of intersection becomes a point of the conic. In the diagram three pairs of neighbored tangents coincide. This procedure results in a statement on inellipses of triangles. From a projective point of view the two triangles and lie perspectively with center . That means there exists a central collineation, which maps the one onto the other triangle. But only in special cases this collineation is an affine scaling. For example for a Steiner inellipse, where the Brianchon point is the centroid.
In the affine plane
Brianchon's theorem is true in both the affine plane and the real projective plane. However, its statement in the affine plane is in a sense less informative and more complicated than that in the projective plane. Consider, for example, five tangent lines to a parabola. These may be considered sides of a hexagon whose sixth side is the line at infinity, but there is no line at infinity in the affine plane. In two instances, a line from a (non-existent) vertex to the opposite vertex would be a line parallel to one of the five tangent lines. Brianchon's theorem stated only for the affine plane would therefore have to be stated differently in such a situation.
The projective dual of Brianchon's theorem has exceptions in the affine plane but not in the |
https://en.wikipedia.org/wiki/Interlocus%20sexual%20conflict | Interlocus sexual conflict is a type of sexual conflict that occurs through the interaction of a set of antagonistic alleles at two or more different loci, or the location of a gene on a chromosome, in males and females, resulting in the deviation of either or both sexes from the fitness optima for the traits. A co-evolutionary arms race is established between the sexes in which either sex evolves a set of antagonistic adaptations that is detrimental to the fitness of the other sex. The potential for reproductive success in one organism is strengthened while the fitness of the opposite sex is weakened. Interlocus sexual conflict can arise due to aspects of male–female interactions such as mating frequency, fertilization, relative parental effort, female remating behavior, and female reproductive rate.
As the sexes demonstrate a significant investment discrepancy for reproduction, interlocus sexual conflict can arise. To achieve reproductive success, a species member will display reproductive characteristics that enhance their ability to reproduce, regardless of whether the fitness of their mate is negatively affected. Sperm production by males is substantially less biologically costly than egg production by females, and sperm are produced in much greater quantities. Consequently, males invest more energy into mating frequency, while females are choosier with mates and invest their energy into offspring quality.
The evolutionary pathways resulting from interlocus sexual conflict form part of interlocus contest evolution, a theory describing the coevolution of different loci in a species through the process of intergenomic conflict. This has led to the proposal that sexual antagonistic coevolution is fueled by interlocus sexual conflict.
Well-evidenced examples come exclusively from the insect world, with the majority of research being conducted in yellow dung flies, Scathophaga stercoraria, and fruit flies, Drosophila melanogaster. Examples outside of these taxa a |
https://en.wikipedia.org/wiki/Symbolic%20method | In mathematics, the symbolic method in invariant theory is an algorithm developed by Arthur Cayley, Siegfried Heinrich Aronhold, Alfred Clebsch, and Paul Gordan in the 19th century for computing invariants of algebraic forms. It is based on treating the form as if it were a power of a degree one form, which corresponds to embedding a symmetric power of a vector space into the symmetric elements of a tensor product of copies of it.
Symbolic notation
The symbolic method uses a compact, but rather confusing and mysterious notation for invariants, depending on the introduction of new symbols a, b, c, ... (from which the symbolic method gets its name) with apparently contradictory properties.
Example: the discriminant of a binary quadratic form
These symbols can be explained by the following example from Gordan. Suppose that
is a binary quadratic form with an invariant given by the discriminant
The symbolic representation of the discriminant is
where a and b are the symbols. The meaning of the expression (ab)2 is as follows. First of all, (ab) is a shorthand form for the determinant of a matrix whose rows are a1, a2 and b1, b2, so
Squaring this we get
Next we pretend that
so that
and we ignore the fact that this does not seem to make sense if f is not a power of a linear form.
Substituting these values gives
Higher degrees
More generally if
is a binary form of higher degree, then one introduces new variables a1, a2, b1, b2, c1, c2, with the properties
What this means is that the following two vector spaces are naturally isomorphic:
The vector space of homogeneous polynomials in A0,...An of degree m
The vector space of polynomials in 2m variables a1, a2, b1, b2, c1, c2, ... that have degree n in each of the m pairs of variables (a1, a2), (b1, b2), (c1, c2), ... and are symmetric under permutations of the m symbols a, b, ....,
The isomorphism is given by mapping aa, bb, .... to Aj. This mapping does not preserve products of polynomials.
More varia |
https://en.wikipedia.org/wiki/Tenonitrozole | Tenonitrozole is an antiprotozoal agent. |
https://en.wikipedia.org/wiki/Coherent%20sheaf | In mathematics, especially in algebraic geometry and the theory of complex manifolds, coherent sheaves are a class of sheaves closely linked to the geometric properties of the underlying space. The definition of coherent sheaves is made with reference to a sheaf of rings that codifies this geometric information.
Coherent sheaves can be seen as a generalization of vector bundles. Unlike vector bundles, they form an abelian category, and so they are closed under operations such as taking kernels, images, and cokernels. The quasi-coherent sheaves are a generalization of coherent sheaves and include the locally free sheaves of infinite rank.
Coherent sheaf cohomology is a powerful technique, in particular for studying the sections of a given coherent sheaf.
Definitions
A quasi-coherent sheaf on a ringed space is a sheaf of -modules which has a local presentation, that is, every point in has an open neighborhood in which there is an exact sequence
for some (possibly infinite) sets and .
A coherent sheaf on a ringed space is a sheaf satisfying the following two properties:
is of finite type over , that is, every point in has an open neighborhood in such that there is a surjective morphism for some natural number ;
for any open set , any natural number , and any morphism of -modules, the kernel of is of finite type.
Morphisms between (quasi-)coherent sheaves are the same as morphisms of sheaves of -modules.
The case of schemes
When is a scheme, the general definitions above are equivalent to more explicit ones. A sheaf of -modules is quasi-coherent if and only if over each open affine subscheme the restriction is isomorphic to the sheaf associated to the module over . When is a locally Noetherian scheme, is coherent if and only if it is quasi-coherent and the modules above can be taken to be finitely generated.
On an affine scheme , there is an equivalence of categories from -modules to quasi-coherent sheaves, taking a module to the as |
https://en.wikipedia.org/wiki/Ballistospore | A ballistospore or ballistoconidia is a spore that is discharged into the air from a living being, usually a species of fungus. With fungi, most types of basidiospores formed on basidia are discharged into the air from the tips of sterigmata. At least 30 thousand species of mushrooms, basidiomycete yeasts, and other fungal groups may discharge ballistospores, sometimes at initial accelerations exceeding 10 thousand times g. |
https://en.wikipedia.org/wiki/Bottromycin | Bottromycin is a macrocyclic peptide with antibiotic activity. It was first discovered in 1957 as a natural product isolated from Streptomyces bottropensis. It has been shown to inhibit methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE) among other Gram-positive bacteria and mycoplasma. Bottromycin is structurally distinct from both vancomycin, a glycopeptide antibiotic, and methicillin, a beta-lactam antibiotic.
Bottromycin binds to the A site of the ribosome and blocks the binding of aminoacyl-tRNA, therefore inhibiting bacterial protein synthesis. Although bottromycin exhibits antibacterial activity in vitro, it has not yet been developed as a clinical antibiotic, potentially due to its poor stability in blood plasma. To increase its stability in vivo, some bottromycin derivatives have been explored.
The structure of bottromycin contains a macrocyclic amidine as well as a thiazole ring. The absolute stereochemistry at several chiral centers has been determined as of 2009. In 2012, a three-dimensional solution structure of bottromycin was published. The solution structure revealed that several methyl groups are on the same face of the structure.
Bottromycin falls within the ribosomally synthesized and post-translationally modified peptide class of natural product.
History
Bottromycin was first isolated from Streptomyces bottropensis in 1957. It has since been identified in at least two other members of the genus Streptomyces; members of Streptomyces are known to be prolific producers of secondary metabolites. Bottromycin has a unique structure, consisting of the macrocyclic amidine linkage and four β-methylated amino acids. Bottromycin blocks aminoacyl tRNA binding to the ribosome by binding to the A site of the 50s subunit. Although bottromycin was discovered over 50 years ago, there was a lack of research following initial studies on bottromycin until recent years. The lack of research is potentially a result of |
https://en.wikipedia.org/wiki/Local%20extinction | Local extinction, also extirpation, is the termination of a species (or other taxon) in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinctions.
Local extinctions mark a change in the ecology of an area. It has sometimes been followed by a replacement of the species taken from other locations, such as with wolf reintroduction.
Discussion
Glaciation is one factor that leads to local extinction. This was the case during the Pleistocene glaciation event in North America. During this period, most of the native North American species of earthworm were killed in places covered by glaciation. This left them open for colonization by European earthworms brought over in soil from Europe.
Species naturally become extirpated from islands over time. The number of species an island can support is limited by its geographical size. Because many islands were relatively recently formed due to climate change at the end of the Pleistocene when the sea level rose, and these islands most likely had the same complement of species as found on the mainland, counting the species which still survive at present on a statistically large enough amount of islands will give the parameters with which certain groups of species such as plants or birds will become less biodiverse on a given island over a given period of time, depending on its size. The same calculations can also be applied to determine when species will disappear from nature parks ('islands' in many senses), mountain tops and mesas (see sky islands), forest remnants or other such distributional patches. This research also demonstrates that certain species are more prone to extinction than others, a species has an intrinsic extinction-ability (incidence function).
Some species exploit or require transient or disturbed habitats, such as vernal pools, a human gut, or burnt woodland after forest fires, and are characterised by highly fluctuating population numbers |
https://en.wikipedia.org/wiki/Collision%20problem | The r-to-1 collision problem is an important theoretical problem in complexity theory, quantum computing, and computational mathematics. The collision problem most often refers to the 2-to-1 version: given even and a function , we are promised that f is either 1-to-1 or 2-to-1. We are only allowed to make queries about the value of for any . The problem then asks how many such queries we need to make to determine with certainty whether f is 1-to-1 or 2-to-1.
Classical solutions
Deterministic
Solving the 2-to-1 version deterministically requires queries, and in general distinguishing r-to-1 functions from 1-to-1 functions requires queries.
This is a straightforward application of the pigeonhole principle: if a function is r-to-1, then after queries we are guaranteed to have found a collision. If a function is 1-to-1, then no collision exists. Thus, queries suffice. If we are unlucky, then the first queries could return distinct answers, so queries is also necessary.
Randomized
If we allow randomness, the problem is easier. By the birthday paradox, if we choose (distinct) queries at random, then with high probability we find a collision in any fixed 2-to-1 function after queries.
Quantum solution
The BHT algorithm, which uses Grover's algorithm, solves this problem optimally by only making queries to f. |
https://en.wikipedia.org/wiki/Psychogenic%20disease | Classified as a "conversion disorder" by the DSM-IV, a psychogenic disease is a disease in which mental stressors cause physical symptoms of different diseases. The manifestation of physical symptoms without biologically identifiable causes results from disruptions of processes in the brain from psychological stress. During a psychogenic disease, neuroimaging has shown that neural circuits affecting functions such as emotion, executive functioning, perception, movement, and volition are inhibited. These disruptions become strong enough to prevent the brain from voluntarily allowing certain actions (e.g. moving a limb). When the brain is unable to signal to the body to perform an action voluntarily, physical symptoms of a disease are presented even though there is no biological identifiable cause. Examples of diseases that are believed by many to be psychogenic include psychogenic seizures, psychogenic polydipsia, psychogenic tremor, and psychogenic pain.
The term psychogenic disease is often used in a similar way to psychosomatic disease. However, the term psychogenic usually implies that psychological factors played a key causal role in the development of the illness. The term psychosomatic is often used in a broader way to describe illnesses with a known medical cause where psychological factors may nonetheless play a role (e.g., asthma can be exacerbated by anxiety).
Diagnosis
With the advent of medical screening technologies, such as electroencephalography (EEG) monitoring, psychogenic diseases are becoming much more common as medical professionals have increasingly precise tools to monitor patients. When a patient does not display typical markers of a disorder that could show up from medical exams, physicians typically diagnose a patient's symptoms as being psychogenic. Research into understanding psychogenic disorders has led to the development of both electronic diagnostic tests for ruling out the usual biological markers of a disorder and new clinical obs |
https://en.wikipedia.org/wiki/List%20of%20oldest%20Edmontonians | This article lists the 25 oldest verified Edmontonians of all time (people from Edmonton, Alberta, all of whom attained the age of at least 105 years). Centenarians have received considerable local recognition in the City of Edmonton due to the Edmonton Aging Symposium, as well as the presence of the Alberta Centre on Aging at the University of Alberta. Edmonton's centenary focus is exemplified in the city's municipal slogan "Official Host City of the Turn of the Century" which was introduced in 1895, following the city's own centennial.
As of 2022, the oldest verified Edmontonian is Margherita Buttiri, who died aged 112 years and 46 days on 23 June 2020.
Municipal recognition
The City of Edmonton honours citizens who become centenarians with a letter from the Mayor.
Oldest verified Edmontonians
See also
Demographics of Edmonton |
https://en.wikipedia.org/wiki/Quantum%20Turing%20machine | A quantum Turing machine (QTM) or universal quantum computer is an abstract machine used to model the effects of a quantum computer. It provides a simple model that captures all of the power of quantum computation—that is, any quantum algorithm can be expressed formally as a particular quantum Turing machine. However, the computationally equivalent quantum circuit is a more common model.
Quantum Turing machines can be related to classical and probabilistic Turing machines in a framework based on transition matrices. That is, a matrix can be specified whose product with the matrix representing a classical or probabilistic machine provides the quantum probability matrix representing the quantum machine. This was shown by Lance Fortnow.
Informal sketch
A way of understanding the quantum Turing machine (QTM) is that it generalizes the classical Turing machine (TM) in the same way that the quantum finite automaton (QFA) generalizes the deterministic finite automaton (DFA). In essence, the internal states of a classical TM are replaced by pure or mixed states in a Hilbert space; the transition function is replaced by a collection of unitary matrices that map the Hilbert space to itself.
That is, a classical Turing machine is described by a 7-tuple .
For a three-tape quantum Turing machine (one tape holding the input, a second tape holding intermediate calculation results, and a third tape holding output):
The set of states is replaced by a Hilbert space.
The tape alphabet symbols are likewise replaced by a Hilbert space (usually a different Hilbert space than the set of states).
The blank symbol is an element of the Hilbert space.
The input and output symbols are usually taken as a discrete set, as in the classical system; thus, neither the input nor output to a quantum machine need be a quantum system itself.
The transition function is a generalization of a transition monoid and is understood to be a collection of unitary matrices that are automorphism |
https://en.wikipedia.org/wiki/Plantar%20digital%20veins | The plantar digital veins arise from plexuses on the plantar surfaces of the digits, and, after sending intercapitular veins to join the dorsal digital veins, unite to form four metatarsal veins. |
https://en.wikipedia.org/wiki/Evolution%20of%20the%20brain | There is much to be discovered about the evolution of the brain and the principles that govern it. While much has been discovered, not everything currently known is well understood. The evolution of the brain has appeared to exhibit diverging adaptations within taxonomic classes such as Mammalia and more vastly diverse adaptations across other taxonomic classes.
Brain to body size scales allometrically. This means as body size changes, so do other physiological, anatomical, and biochemical constructs connecting the brain to the body. Small bodied mammals have relatively large brains compared to their bodies whereas large mammals (such as whales) have a smaller brain to body ratios. If brain weight is plotted against body weight for primates, the regression line of the sample points can indicate the brain power of a primate species. Lemurs for example fall below this line which means that for a primate of equivalent size, we would expect a larger brain size. Humans lie well above the line indicating that humans are more encephalized than lemurs. In fact, humans are more encephalized compared to all other primates. This means that human brains have exhibited a larger evolutionary increase in its complexity relative to its size. Some of these evolutionary changes have been found to be linked to multiple genetic factors, such as proteins and other organelles.
Early history of brain development
One approach to understanding overall brain evolution is to use a paleoarchaeological timeline to trace the necessity for ever increasing complexity in structures that allow for chemical and electrical signaling. Because brains and other soft tissues do not fossilize as readily as mineralized tissues, scientists often look to other structures as evidence in the fossil record to get an understanding of brain evolution. This, however, leads to a dilemma as the emergence of organisms with more complex nervous systems with protective bone or other protective tissues that can then |
https://en.wikipedia.org/wiki/Japan%20Radio%20Company | is a Japanese company specialising in the field of wireless electronics for the communications industry.
History
Established in 1915, the company has produced a wide variety of products including marine electronics, measuring equipment for telecommunication, radio broadcasting equipment, and amateur radio equipment, including the JST-145dx/JST-245dx HF transceivers, which were the last amateur radio transceivers produced by JRC, ending in 2002. |
https://en.wikipedia.org/wiki/Journal%20club | A journal club is a group of individuals who meet regularly to critically evaluate recent articles in the academic literature, such as the scientific literature, medical literature, or philosophy literature. Journal clubs are usually organized around a defined subject in basic or applied research. For example, the application of evidence-based medicine to some area of medical practice can be facilitated by a journal club. Typically, each participant can voice their view relating to several questions such as the appropriateness of the research design, the statistics employed, the appropriateness of the controls that were used, etc. There might be an attempt to synthesize together the results of several papers, even if some of these results might first appear to contradict each other. Even if the results of the study are seen as valid, there might be a discussion of how useful the results are and if these results might lead to new research or to new applications.
Journal clubs are sometimes used in the education of graduate or professional students. These help make the student(s) become more familiar with the advanced literature in their new field of study. In addition, these journal clubs help improve the students' skills of understanding and debating current topics of active interest in their field. This type of journal club may sometimes be taken for credit. Research laboratories may also organize journal clubs for all researchers in the lab to help them keep up with the literature produced by others who work in their field.
Traditional journal club
Traditionally, journal clubs have met weekly or monthly to discuss current research in a topic relevant to the field. An analysis of one hundred publications describing and evaluating journal clubs found that they are most effective if they have a clearly identified leader and have an established purpose that all articles can be linked to.
Online journal clubs
Prominent journals and scientific societies have beg |
https://en.wikipedia.org/wiki/Group%20A%20nerve%20fiber | Group A nerve fibers are one of the three classes of nerve fiber as generally classified by Erlanger and Gasser. The other two classes are the group B nerve fibers, and the group C nerve fibers. Group A are heavily myelinated, group B are moderately myelinated, and group C are unmyelinated.
The other classification is a sensory grouping that uses the terms type Ia and type Ib, type II, type III, and type IV, sensory fibers.
Types
There are four subdivisions of group A nerve fibers: alpha (α) Aα; beta (β) Aβ; , gamma (γ) Aγ, and delta (δ) Aδ. These subdivisions have different amounts of myelination and axon thickness and therefore transmit signals at different speeds. Larger diameter axons and more myelin insulation lead to faster signal propagation.
Group A nerves are found in both motor and sensory pathways.
Different sensory receptors are innervated by different types of nerve fibers. Proprioceptors are innervated by type Ia, Ib and II sensory fibers, mechanoreceptors by type II and III sensory fibers, and nociceptors and thermoreceptors by type III and IV sensory fibers.
Type Aα fibers include the type Ia and type Ib sensory fibers of the alternative classification system, and are the fibers from muscle spindle endings and the Golgi tendon, respectively.
Type Aβ fibres, and type Aγ, are the type II afferent fibers from stretch receptors. Type Aβ fibres from the skin are mostly dedicated to touch. However a small fraction of these fast fibres, termed "ultrafast nociceptors", also transmit pain.
Type Aδ fibers are the afferent fibers of nociceptors. Aδ fibers carry information from peripheral mechanoreceptors and thermoreceptors to the dorsal horn of the spinal cord. This pathway describes the first-order neuron. Aδ fibers serve to receive and transmit information primarily relating to acute pain (sharp, immediate, and relatively short-lasting). This type of pain can result from several classifications of stimulants: temperature-induced, mechanical, and chem |
https://en.wikipedia.org/wiki/Ramsey%27s%20theorem | In combinatorics, Ramsey's theorem, in one of its graph-theoretic forms, states that one will find monochromatic cliques in any edge labelling (with colours) of a sufficiently large complete graph. To demonstrate the theorem for two colours (say, blue and red), let and be any two positive integers. Ramsey's theorem states that there exists a least positive integer for which every blue-red edge colouring of the complete graph on vertices contains a blue clique on vertices or a red clique on vertices. (Here signifies an integer that depends on both and .)
Ramsey's theorem is a foundational result in combinatorics. The first version of this result was proved by Frank Ramsey. This initiated the combinatorial theory now called Ramsey theory, that seeks regularity amid disorder: general conditions for the existence of substructures with regular properties. In this application it is a question of the existence of monochromatic subsets, that is, subsets of connected edges of just one colour.
An extension of this theorem applies to any finite number of colours, rather than just two. More precisely, the theorem states that for any given number of colours, , and any given integers , there is a number, , such that if the edges of a complete graph of order are coloured with different colours, then for some between 1 and , it must contain a complete subgraph of order whose edges are all colour . The special case above has (and and ).
Examples
R(3, 3) = 6
Suppose the edges of a complete graph on 6 vertices are coloured red and blue. Pick a vertex, . There are 5 edges incident to and so (by the pigeonhole principle) at least 3 of them must be the same colour. Without loss of generality we can assume at least 3 of these edges, connecting the vertex, , to vertices, , and , are blue. (If not, exchange red and blue in what follows.) If any of the edges, , , , are also blue then we have an entirely blue triangle. If not, then those three edges are all red and we hav |
https://en.wikipedia.org/wiki/XKMS | XML Key Management Specification (XKMS) uses the web services framework to make it easier for developers to secure inter-application communication using public key infrastructure (PKI). XML Key Management Specification is a protocol developed by W3C which describes the distribution and registration of public keys. Services can access an XKMS compliant server in order to receive updated key information for encryption and authentication.
Architecture
XKMS consists of two parts:
X-KISS XML Key Information Service Specification
X-KRSS XML Key Registration Service Specification
The X-KRSS defines the protocols needed to register public key information. X-KRSS can generate the key material, making key recovery easier than when created manually.
The X-KISS outlines the syntax that applications should use to delegate some or all of the tasks needed to process the key information element of an XML signature to a trust service.
In both cases the goal of XKMS is to allow all the complexity of traditional PKI implementations to be offloaded from the client to an external service. While this approach was originally suggested by Diffie and Hellman in their New Directions paper this was generally considered impractical at the time leading to commercial development focusing on the certificate based approach proposed by Loren Kohnfelder.
Development history
The team that developed the original XKMS proposal submitted to the W3C included Warwick Ford, Phillip Hallam-Baker (editor) and Brian LaMacchia. The architectural approach is closely related to the MIT PGP Key server originally created and maintained by Brian LaMacchia. The realization in XML is closely related to SAML, the first edition of which was also edited by Hallam-Baker.
At the time XKMS was proposed no security infrastructure was defined for the then entirely new SOAP protocol for Web Services. As a result, a large part of the XKMS specification is concerned with the definition of security 'bindings' for spe |
https://en.wikipedia.org/wiki/Multi-configuration%20time-dependent%20Hartree | Multi-configuration time-dependent Hartree (MCTDH) is a general algorithm to solve the time-dependent Schrödinger equation for multidimensional dynamical systems consisting of distinguishable particles. MCTDH can thus determine the quantal motion of the nuclei of a molecular system evolving on one or several coupled electronic potential energy surfaces. MCTDH by its very nature is an approximate method. However, it can be made as accurate as any competing method, but its numerical efficiency deteriorates with growing accuracy.
MCTDH is designed for multi-dimensional problems, in particular for problems that are difficult or even impossible to attack in a conventional way. There is no or only little gain when treating systems with less than three degrees of freedom by MCTDH. MCTDH will in general be best suited for systems with 4 to 12 degrees of freedom. Because of hardware limitations it may in general not be possible to treat much larger systems. For a certain class of problems, however, one can go much further. The MCTDH program package has recently been generalised to enable the propagation of density operators. |
https://en.wikipedia.org/wiki/Square%20root%20of%20a%20matrix | In mathematics, the square root of a matrix extends the notion of square root from numbers to matrices. A matrix is said to be a square root of if the matrix product is equal to .
Some authors use the name square root or the notation only for the specific case when is positive semidefinite, to denote the unique matrix that is positive semidefinite and such that (for real-valued matrices, where is the transpose of ).
Less frequently, the name square root may be used for any factorization of a positive semidefinite matrix as , as in the Cholesky factorization, even if . This distinct meaning is discussed in .
Examples
In general, a matrix can have several square roots. In particular, if then as well.
The 2×2 identity matrix has infinitely many square roots. They are given by
and
where are any numbers (real or complex) such that .
In particular if is any Pythagorean triple—that is, any set of positive integers such that , then
is a square root matrix of which is symmetric and has rational entries.
Thus
Minus identity has a square root, for example:
which can be used to represent the imaginary unit and hence all complex numbers using 2×2 real matrices, see Matrix representation of complex numbers.
Just as with the real numbers, a real matrix may fail to have a real square root, but have a square root with complex-valued entries.
Some matrices have no square root. An example is the matrix
While the square root of a nonnegative integer is either again an integer or an irrational number, in contrast an integer matrix can have a square root whose entries are rational, yet non-integral, as in examples above.
Positive semidefinite matrices
A symmetric real n × n matrix is called positive semidefinite if for all (here denotes the transpose, changing a column vector into a row vector).
A square real matrix is positive semidefinite if and only if for some matrix .
There can be many different such matrices .
A positive semidefinite matrix |
https://en.wikipedia.org/wiki/Research%20Plot%2030 | Research Plot 30, is a historic agriculture site on the North Dakota State University campus in Fargo, North Dakota. When the pioneers broke up the grass prairie sod, flax was usually one of the first crops sown. If flax was sown continuously or with short rotations between subsequent flax crops, the flax became diseased and was called "flax sick" by farmers. The symptoms were wilting and dying flax plants during the growing season. The site is located near Centennial Avenue and 18th Street North. Flax was first planted at the site in 1894 by Professor Henry L. Bolley, a noted researcher in flax botany. By 1900, the flax plants were dead or dying. Bolley identified flax pathogens introduced by the plants themselves as the cause, and further identified resistant plants. Flax breeding programs from all over the world have sent material to NDSU to be tested for resistance to flax wilt in Plot 30.
The site was listed on the National Register of Historic Places in 1991. At the time of the nomination, the site had been cultivated in flax for nearly a century.
See also
Research Plot 2, also NRHP-listed, nearby, famous as site of wheat research
Beatrice Willard Alpine Tundra Research Plots, Estes Park, Colorado, NRHP-listed |
https://en.wikipedia.org/wiki/Long%20number | A long number (e.g. +44 7624 800555 in international notation or 07624 800555 in UK national notation), also known as a virtual mobile number (VMN), dedicated phone number MSISDN or long code, is a reception mechanism used by businesses to receive SMS messages and voice calls. As well as being internationally available, long numbers enable businesses to have their own number, rather than short codes which are generally shared across a lot of brands. Long numbers allows a wide range of industries to generate large amounts of mobile-originated SMS from the subscribers, such as wireless application service providers, mobile virtual network operators, mobile virtual network enablers, SMS aggregators, e-sellers, advertising agencies, media channels and mobile infrastructure providers.
Long numbers vs. short codes
Both long numbers and short codes have their advantages and disadvantages.
International accessibility is useful for global organizations who wish to run international campaigns. Limited to national borders, short codes have to be activated in each country where the campaign will take place, which might be expensive and time-consuming. For long-term campaigns or any other assignment, long numbers are also a good solution, as the number can be assigned exclusively for a long term. The long numbers option can be obtained directly from an SMS provider with SS7 access, which is the shortest way possible to have an SMS reception option. Alternatively, long numbers can be obtained from SMS aggregators or SMS providers. To have access to a short code, service providers must enter a bilateral agreement with the mobile network operator that actually owns the number. This process can take time, and potentially cause delays in implementing campaigns. Alternatively, service providers can rent short codes from aggregators, creating another middleman in the value-chain. Premium messaging services are not possible on long numbers; those require short codes and operator a |
https://en.wikipedia.org/wiki/Permanent%20cell | Permanent cells are cells that are incapable of regeneration. These cells are considered to be terminally differentiated and non-proliferative in postnatal life. This includes neurons, heart cells, skeletal muscle cells and red blood cells. Although these cells are considered permanent in that they neither reproduce nor transform into other cells, this does not mean that the body cannot create new versions of these cells. For instance, structures in the bone marrow produce new red blood cells constantly, while skeletal muscle damage can be repaired by underlying satellite cells, which fuse to become a new skeletal muscle cell.
Disease and virology studies can use permanent cells to maintain cell count and accurately quantify the effects of vaccines. Some embryology studies also use permanent cells to avoid harvesting embryonic cells from pregnant animals; since the cells are permanent, they may be harvested at a later age when an animal is fully developed.
See also
Labile cells, which multiply constantly throughout life
Stable cells, which only multiply when receiving external stimulus to do so |
https://en.wikipedia.org/wiki/List%20of%20mathematical%20societies | This article provides a list of mathematical societies.
International
African Mathematical Union
Association for Women in Mathematics
Circolo Matematico di Palermo
European Mathematical Society
European Women in Mathematics
Foundations of Computational Mathematics
International Association for Cryptologic Research
International Association of Mathematical Physics
International Linear Algebra Society
International Mathematical Union
International Statistical Institute
International Society for Analysis, its Applications and Computation
International Society for Mathematical Sciences
Kurt Gödel Society
Mathematical Council of the Americas (MCofA)
Mathematical Society of South Eastern Europe (MASSEE)
Mathematical Optimization Society
Maths Society
Ramanujan Mathematical Society
Quaternion Society
Society for Industrial and Applied Mathematics
Southeast Asian Mathematical Society (SEAMS)
Spectra (mathematical association)
Unión Matemática de América Latina y el Caribe (UMALCA)
Young Mathematicians Network
Honor societies
Kappa Mu Epsilon
Mu Alpha Theta
Pi Mu Epsilon
National and subnational
Arranged as follows: Society name in English (Society name in home-language; Abbreviation if used), Country and/or subregion/city if not specified in name.
This list is sorted by continent.
Africa
Algeria Mathematical Society
Gabon Mathematical Society
South African Mathematical Society
Asia
Bangladesh Mathematical Society
Calcutta Mathematical Society (CalMathSoc), Kolkata, India
Chinese Mathematical Society
Indian Mathematical Society
Iranian Mathematical Society
Israel Mathematical Union
Jadavpur University Mathematical Society (JMS), Jadavpur, India
Kerala Mathematical Association, Kerala State, India
Korean Mathematical Society, South Korea
Mathematical Society of Japan
Mathematical Society of the Philippines
Pakistan Mathematical Society
Turkish Mathematical Society
Europe
Albanian Mathematical Association
Armenian Mathematic |
https://en.wikipedia.org/wiki/Genera%20%28operating%20system%29 | Genera is a commercial operating system and integrated development environment for Lisp machines created by Symbolics. It is essentially a fork of an earlier operating system originating on the Massachusetts Institute of Technology (MIT) AI Lab's Lisp machines which Symbolics had used in common with Lisp Machines, Inc. (LMI), and Texas Instruments (TI). Genera was also sold by Symbolics as Open Genera, which runs Genera on computers based on a Digital Equipment Corporation (DEC) Alpha processor using Tru64 UNIX. In 2021 a new version was released as Portable Genera which runs on DEC Alpha, Tru64 UNIX, x86-64 and Arm64 Linux, x86-64 and Apple Silicon M Series macOS. It is released and licensed as proprietary software.
Genera is an example of an object-oriented operating system based on the programming language Lisp.
Genera supports incremental and interactive development of complex software using a mix of programming styles with extensive support for object-oriented programming.
MIT's Lisp machine operating system
The Lisp Machine operating system was written in Lisp Machine Lisp. It was a one-user workstation initially targeted at software developers for artificial intelligence (AI) projects. The system had a large bitmap screen, a mouse, a keyboard, a network interface, a disk drive, and slots for expansion. The operating system was supporting this hardware and it provided (among others):
code for a frontend processor
means to boot the operating system
virtual memory management
garbage collection
interface to various hardware: mouse, keyboard, bitmap frame buffer, disk, printer, network interface
an interpreter and a native code compiler for Lisp Machine Lisp
an object system: Flavors
a graphical user interface (GUI) window system and window manager
a local file system
support for the Chaosnet (CHAOS) network
an Emacs-like Editor named Zmacs
a mail program named Zmail
a Lisp listener
a debugger
This was already a complete one-user Lisp-based op |
https://en.wikipedia.org/wiki/Windows%20Server%202008 | Windows Server 2008, codenamed "Longhorn Server", is the fourth release of the Windows Server operating system produced by Microsoft as part of the Windows NT family of the operating systems. It was released to manufacturing on February 4, 2008, and generally to retail on February 27, 2008. Derived from Windows Vista, Windows Server 2008 is the successor of Windows Server 2003 and the predecessor to Windows Server 2008 R2.
Windows Server 2008 removed support for processors without ACPI. It is the first version of Windows Server that includes Hyper-V and is also the final version of Windows Server that supports IA-32-based processors (also known as 32-bit processors). Its successor, Windows Server 2008 R2, requires a 64-bit processor in any supported architecture (x86-64 for x86 and Itanium).
As of July 2019, 60% of Windows servers were running Windows Server 2008.
History
Microsoft had released Windows Vista to mixed reception, and their last Windows Server release was based on Windows XP. The operating system's working title was Windows Server Codename "Longhorn", but was later changed to Windows Server 2008 when Microsoft chairman Bill Gates announced it during his keynote address at WinHEC on May 16, 2007.
Beta 1 was released on July 27, 2005; Beta 2 was announced and released on May 23, 2006, at WinHEC 2006 and Beta 3 was released publicly on April 25, 2007. Release Candidate 0 was released to the general public on September 24, 2007 and Release Candidate 1 was released to the general public on December 5, 2007. Windows Server 2008 was released to manufacturing on February 4, 2008, and officially launched on the 27th of that month.
Features
Windows Server 2008 is built from the same codebase as Windows Vista and thus it shares much of the same architecture and functionality. Since the codebase is common, Windows Server 2008 inherits most of the technical, security, management and administrative features new to Windows Vista such as the rewritten networki |
https://en.wikipedia.org/wiki/Supportworks | Supportworks is an issue tracking system designed for use in help desk and information technology (IT) environments. Two branches of the software are developed concurrently, Supportworks ITSM, a certified ITIL compatible IT service management (ITSM) solution, and Supportworks Helpdesk Professional.
Design
Issues tracked in Supportworks are known as "calls." Calls are classified using a hierarchical model known as "problem profiles." This model enables a drill down method to classify calls with each level increasing specificity of the classification. Supportworks groups analysts into "support groups." Calls may be assigned to a support group, or to a specific analyst.
A call's state at any given time is denoted by one of several different "condition codes," each is expressed visually by a different color. Black indicates a pending state (that work is in progress on the call) or that the call is "closed" (required work is completed). Blue denotes a call that no one currently has responsibility for; that it has not been "assigned" to or "accepted" by an analyst. Green colored calls are "on hold," meaning further user input is required to complete the call and therefore "paused" for a specific amount of time. Red is reserved for calls that are "off hold" or that require urgent attention.
Each Supportworks call is associated with a service level agreement (SLA). A call's SLA can be generated from its metadata, such as the customer, department, site, inventory item, or problem profile associated with the call. Each SLA incorporates a "response time" and "fix time" related to the call. Triggers are programmed based on the response time and fix time to ensure the SLA is not violated. For instance, if a call is approaching its fix time, but its issue has not been resolved, a help desk manager can be notified, the call can be transferred to a different group, or the call's condition code can be changed.
Supportworks provides a tool to track widespread incidents that may |
https://en.wikipedia.org/wiki/Mutationism | Mutationism is one of several alternatives to evolution by natural selection that have existed both before and after the publication of Charles Darwin's 1859 book On the Origin of Species. In the theory, mutation was the source of novelty, creating new forms and new species, potentially instantaneously, in sudden jumps. This was envisaged as driving evolution, which was thought to be limited by the supply of mutations.
Before Darwin, biologists commonly believed in saltationism, the possibility of large evolutionary jumps, including immediate speciation. For example, in 1822 Étienne Geoffroy Saint-Hilaire argued that species could be formed by sudden transformations, or what would later be called macromutation. Darwin opposed saltation, insisting on gradualism in evolution as geology's uniformitarianism. In 1864, Albert von Kölliker revived Geoffroy's theory. In 1901 the geneticist Hugo de Vries gave the name "mutation" to seemingly new forms that suddenly arose in his experiments on the evening primrose Oenothera lamarckiana. In the first decade of the 20th century, mutationism, or as de Vries named it mutationstheorie, became a rival to Darwinism supported for a while by geneticists including William Bateson, Thomas Hunt Morgan, and Reginald Punnett.
Understanding of mutationism is clouded by the mid-20th century portrayal of the early mutationists by supporters of the modern synthesis as opponents of Darwinian evolution and rivals of the biometrics school who argued that selection operated on continuous variation. In this portrayal, mutationism was defeated by a synthesis of genetics and natural selection that supposedly started later, around 1918, with work by the mathematician Ronald Fisher. However, the alignment of Mendelian genetics and natural selection began as early as 1902 with a paper by Udny Yule, and built up with theoretical and experimental work in Europe and America. Despite the controversy, the early mutationists had by 1918 already accepted nat |
https://en.wikipedia.org/wiki/Cookies%20and%20cream | Cookies and cream (or cookies 'n cream) is a variety of ice cream, milkshake and other desserts that includes chocolate sandwich cookies, with the most popular version containing hand or pre-crumbled cookies from Nabisco's Oreo brand under a licensing agreement. Cookies and cream ice cream generally mixes in crumbled chocolate sandwich cookies into vanilla ice cream, though variations exist which might instead use chocolate, coffee or mint ice cream.
History
There are competing claims as to who first invented and marketed cookies and cream ice cream.
Malcolm Stogo, an ice cream consultant, claimed to have created the flavor in 1976, 1977 or 1978.
South Dakota State University claims the flavor was invented at the university's dairy plant in 1979 by plant manager Shirley Seas and students Joe Leedom and Joe Van Treeck.
In a 2005 press release, Blue Bell Creameries claimed they were the first company to mass-produce the flavor, in 1980. In 2006, The New York Times reported that Blue Bell made "no claim to have invented it but certainly pioneered the flavor." However, as of 2020, the company's website proclaimed, "We were first to create this innovative flavor." Blue Bell Creameries applied to register the trademark "Cookies 'n Cream" in 1981.
John Harrison, the official taster for Dreyer's/Edy's Ice Cream, claims he invented it first for the company in 1982
Another claimant is Steve Herrell of Massachusetts' Herrell's Ice Cream.
In 1983, cookies and cream became one of the top five best-selling flavors of ice cream.
See also
Hershey's Cookies 'n' Creme |
https://en.wikipedia.org/wiki/Wireless%20Telephony%20Applications%20Interface | The Wireless Telephone Applications Interface (WTAI) is a protocol used in conjunction with the Wireless Application Protocol (WAP) to allow a phone number to be linked to a web page. |
https://en.wikipedia.org/wiki/Deep%20water%20culture | Deep water culture (DWC) is a hydroponic method of plant production by means of suspending the plant roots in a solution of nutrient-rich, oxygenated water. Also known as deep flow technique (DFT), floating raft technology (FRT), or raceway, this method uses a rectangular tank less than one foot deep filled with a nutrient-rich solution with plants floating in Styrofoam boards on top. This method of floating the boards on the nutrient solution creates a near friction-less conveyor belt of floating rafts. DWC, along with nutrient film technique (NFT), and aggregate culture, is considered to be one of the most common hydroponic systems used today. Typically, DWC is used to grow short-term, non-fruiting crops such as leafy greens and herbs. The large volume of water helps mitigate rapid changes in temperature, pH, electrical conductivity (EC), and nutrient solution composition.
Hobby methods
Deep water culture has also been used by hobby growers. Net pots, plastic pots with netting to allow roots to grow through their surface, are filled with a hydroponic medium such as Hydroton or Rockwool to hold the base of the plant. In some cases net pots are not needed. For oxygenation of the hydroponic solution, an airstone is added. This air stone is then connected to an airline that runs to an air pump.
As the plant grows, the root mass stretches through the rockwool or hydroton into the water below. Under ideal growing conditions, plants are able to grow a root mass that comprises the entire bin in a loosely packed mass. As the plant grows and consumes nutrients the pH and EC of the water fluctuate. For this reason, frequent monitoring must be kept of the nutrient solution to ensure that it remains in the uptake range of the crop. A pH that is too high or too low will make certain nutrients unavailable for uptake by plants. Generally, the best pH for hydroponic crops is around 5.5–6.0. In terms of EC, too low means that there is a low salt content, usually meaning a lac |
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