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https://en.wikipedia.org/wiki/Full-body%20CT%20scan | A full-body scan is a scan of the patient's entire body as part of the diagnosis or treatment of illnesses. If computed tomography (CAT) scan technology is used, it is known as a full-body CT scan, though many medical imaging technologies can perform full-body scans.
Indications
Full-body CT scans allow a transparent view of the body. For polytrauma patients, aggressive use of full-body CT scanning improves early diagnosis of injury and improves survival rates,
with widespread adoption of the technique seen worldwide.
Full-body CT scans are not indicated in patients with minor or single system trauma, and should be avoided in such patients.
Many possible malignancies are discovered with a full-body scan, but these are almost always benign. These may not be related to any disease, and may be benign growths, scar tissue, or the remnants of previous infections. CT scanning for other reasons sometimes identifies these "incidentalomas".
However, the significance of radiation exposure as well as costs associated with these studies must be considered, especially in patients with low energy mechanisms of injury and absent physical examination findings consistent with major trauma.
A full-body scan has the potential to identify disease (e.g. cancer) in early stages, and early identification can improve the success of curative efforts. Controversy arises from the use of full-body scans in the screening of patients who have no signs or symptoms suggestive of a disease. As with any test that screens for disease, the risks of full-body CT scans need to be weighed against the benefit of identifying a treatable disease at an early stage.
An alternative to a full-body CT scan may be Magnetic resonance imaging (MRI) scans. MRI scans are generally more expensive than CT but do not expose the patient to ionizing radiation and are being evaluated for their potential value in screening.
Risks and complications
Compared to most other diagnostic imaging procedures, CT scans result |
https://en.wikipedia.org/wiki/Havriliak%E2%80%93Negami%20relaxation | The Havriliak–Negami relaxation is an empirical modification of the Debye relaxation model in electromagnetism. Unlike the Debye model, the Havriliak–Negami relaxation accounts for the asymmetry and broadness of the dielectric dispersion curve. The model was first used to describe the dielectric relaxation of some polymers, by adding two exponential parameters to the Debye equation:
where is the permittivity at the high frequency limit, where is the static, low frequency permittivity, and is the characteristic relaxation time of the medium. The exponents and describe the asymmetry and broadness of the corresponding spectra.
Depending on application, the Fourier transform of the stretched exponential function can be a viable alternative that has one parameter less.
For the Havriliak–Negami equation reduces to the Cole–Cole equation, for to the Cole–Davidson equation.
Mathematical properties
Real and imaginary parts
The storage part and the loss part of the permittivity (here: with ) can be calculated as
and
with
Loss peak
The maximum of the loss part lies at
Superposition of Lorentzians
The Havriliak–Negami relaxation can be expressed as a superposition of individual Debye relaxations
with the real valued distribution function
where
if the argument of the arctangent is positive, else
Noteworthy, becomes imaginary valued for
and complex valued for
Logarithmic moments
The first logarithmic moment of this distribution, the average logarithmic relaxation time is
where is the digamma function and the Euler constant.
Inverse Fourier transform
The inverse Fourier transform of the Havriliak-Negami function (the corresponding time-domain relaxation function) can be numerically calculated. It can be shown that the series expansions involved are special cases of the Fox–Wright function. In particular, in the time-domain the corresponding of can be represented as
where is the Dirac delta function and
is a special instance of the Fox–W |
https://en.wikipedia.org/wiki/PHBV | Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), commonly known as PHBV, is a polyhydroxyalkanoate-type polymer. It is biodegradable, nontoxic, biocompatible plastic produced naturally by bacteria and a good alternative for many non-biodegradable synthetic polymers. It is a thermoplastic linear aliphatic polyester. It is obtained by the copolymerization of 3-hydroxybutanoic acid and 3-hydroxypentanoic acid. PHBV is used in speciality packaging, orthopedic devices and in controlled release of drugs. PHBV undergoes bacterial degradation in the environment.
History
PHBV was first manufactured in 1983 by Imperial Chemical Industries (ICI). It is commercialized under the trade name Biopol. ICI (Zeneca) sold it to Monsanto in 1996. This was then obtained by Metabolix in 2001. Biomer L is the trade name of PHBV from Biomer.
Synthesis
PHBV is synthesized by bacteria as storage compounds under growth limiting conditions. It can be produced from glucose and propionate by the recombinant Escherichia coli strains. Many other bacteria like Paracoccus denitrificans and Ralstonia eutropha are also capable of producing it.
It can also be synthesized from genetically engineered plants.
PHBV is a copolymer of 3-hydroxybutanoic acid and 3-hydroxypentanoic acid. PHBV may also be synthesized from butyrolactone and valerolactone in the presence of oligomeric aluminoxane as catalyst.
Structure
The monomers, 3-hydroxybutanoic acid and 3-hydroxypentanoic acid, are joined by ester bonds; the back bone of the polymer is made up of carbon and oxygen atoms.
The property of the PHBV depends upon the ratio of these two monomers in it.
3-hydroxybutanoic acid provides stiffness while 3-hydroxypentanoic acid promotes flexibility. Thus PHBV can be made to resemble either polypropylene or polyethylene by changing the ratio of monomers. Increase in the ratio of 3-hydroxybutanoic acid to 3-hydroxypentanoic acid results in an increase in melting point, water permeability, glass transition temperat |
https://en.wikipedia.org/wiki/Incongruent%20melting | Incongruent melting occurs when a solid substance does not melt uniformly, so that the chemical composition of the resulting liquid is not the same as that of the original solid. During incongruent melting a new solid of different composition forms. For example, melting of orthoclase (KAlSi3O8) produces leucite (KAlSi2O6) in addition to a melt. The melt produced is richer in silica (SiO2). The proportions of leucite and melt created can be recombined to yield the bulk composition of the starting feldspar. Another mineral that can melt incongruently is enstatite (Mg2Si2O6), which produces forsterite (Mg2SiO4) in addition to a melt richer in SiO2 when melting at low pressure. Enstatite melts congruently at higher pressures between 2.5 and 5.5 kilobars.
See also
Congruent melting
Incongruent transition
Phase diagram |
https://en.wikipedia.org/wiki/Pseudo-LRU | Pseudo-LRU or PLRU is a family of cache algorithms which improve on the performance of the Least Recently Used (LRU) algorithm by replacing values using approximate measures of age rather than maintaining the exact age of every value in the cache.
PLRU usually refers to two cache replacement algorithms: tree-PLRU and bit-PLRU.
Tree-PLRU
Tree-PLRU is an efficient algorithm to select an item that most likely has not been accessed very recently, given a set of items and a sequence of access events to the items.
This technique is used in the CPU cache of the Intel 486 and in many processors in the PowerPC family, such as Freescale's PowerPC G4 used by Apple Computer.
The algorithm works as follows: consider a binary search tree for the items in question. Each node of the tree has a one-bit flag denoting "go left to insert a pseudo-LRU element" or "go right to insert a pseudo-LRU element". To find a pseudo-LRU element, traverse the tree according to the values of the flags. To update the tree with an access to an item N, traverse the tree to find N and, during the traversal, set the node flags to denote the direction that is opposite to the direction taken.
This algorithm can be sub-optimal since it is an approximation. For example, in the above diagram with A, C, B, D cache lines, if the access pattern was: C, B, D, A, on an eviction, B would chosen instead of C. This is because both A and C are in the same half and accessing A directs the algorithm to the other half that does not contain cache line C.
Bit-PLRU
Bit-PLRU stores one status bit for each cache line. These bits are called MRU-bits. Every access to a line sets its MRU-bit to 1, indicating that the
line was recently used. Whenever the last remaining 0 bit of a set's status bits is
set to 1, all other bits are reset to 0. At cache misses, the leftmost line whose MRU-bit is 0 is replaced.
See also
Cache algorithms |
https://en.wikipedia.org/wiki/Tomohiro%20Tachi | Tomohiro Tachi (, born 1982) is a Japanese academic who studies origami from an interdisciplinary perspective, combining approaches from the mathematics of paper folding, structural rigidity, computational geometry, architecture, and materials science. His work was profiled in "The Origami Revolution" (2017), part of the Nova series of US science documentaries. He is a professor at the University of Tokyo.
Education and career
Tachi studied engineering and architecture at the University of Tokyo, earning bachelor's and master's degrees in 2005 and 2007 respectively, and completing his Ph.D. in 2010. He became an assistant professor in the Department of General Systems Studies at the University of Tokyo in 2010, and became an associate professor in 2018, adding at the same time affiliations with the Department of Information and Graphic Sciences and Department of Architecture.
Contributions
Tachi has been called a "renowned origami artist", and "one of the world experts on rigid origami. His artworks include a "calculated and precise" nudibranch, folded from mirror-finished metal, and an origami version of the Utah teapot, exhibited at the Tikotin Museum of Japanese Art in Israel.
With Erik Demaine, he has developed software that can automatically transform any three-dimensional object, represented as a polygon mesh, into an origami model of the object. His research also includes generalized versions of the Miura fold that can be used to model any smooth surface, and bistable hyperbolic paraboloid structures formed from nested square origami folds.
With Hiroya Tanaka, he is the author of the 2020 Japanese-language book コンピュテーショナル・ファブリケーション [Computational Fabrication: Design and Science of Origami and Tessellation].
Recognition
In 2009, Tachi won the Hangai Prize of the International Association for Shell and Spatial Structures (IASS), for his work on quadrilateral mesh origami. His work with Kōryō Miura on flexible polyhedra derived from the Miura fold won the 2 |
https://en.wikipedia.org/wiki/Streamer%20discharge | In electromagnetism, a streamer discharge, also known as filamentary discharge, is a type of transient electric discharge which forms at the surface of a conductive electrode carrying a high voltage in an insulating medium such as air. Streamers are luminous writhing branching sparks, plasma channels composed of ionized air molecules, which repeatedly strike out from the electrode into the air.
Like the related corona discharges and brush discharges, a streamer discharge represents a region around a high voltage conductor where the air has suffered electrical breakdown and become conductive (ionized), so electric charge is leaking off the electrode into the air. It occurs when the electric field at the surface of a conductor exceeds the dielectric strength of air, around 30 kilovolts per centimeter. When the electric field created by the applied voltage reaches this threshold, accelerated electrons strike air molecules with enough energy to knock other electrons off them, ionizing them, and the freed electrons go on to strike more molecules in a chain reaction. These electron avalanches (Townsend discharges) create ionized, electrically conductive regions in the air near the electrode. The space charge created by the electron avalanches gives rise to an additional electric field, causing the ionized region to grow at its ends, forming a finger-like discharge called a streamer.
Streamers are transient (exist only for a short time) and filamentary, which makes them different from corona discharges. They are used in applications such as ozone production, air purification or plasma medicine. If a streamer reaches the opposite polarity conductor it creates an ionized conductive path through which a large current can flow, releasing a large amount of heat, resulting in an electric arc; this is the process through which lightning leaders create a path for lightning bolts. Streamers can also be observed as sprites in the upper atmosphere. Due to the low pressure, |
https://en.wikipedia.org/wiki/Computational%20models%20in%20epilepsy | Computational models in epilepsy mainly focus on describing an electrophysiological manifestation associated with epilepsy called seizures. For this purpose, computational neurosciences use differential equations to reproduce the temporal evolution of the signals recorded experimentally. A book published in 2008, Computational Neuroscience in Epilepsy,. summarizes different works done up to this time. The goals of using its models are diverse, from prediction to comprehension of underlying mechanisms.
The crisis phenomenon (seizure) exists and shares certain dynamical properties across different scales and different organisms. It is possible to distinguish different approaches: the phenomenological models focus on the dynamics observed, generally reduced to few dimension it facilitates the study from the point of view of the theory of dynamical systems and more mechanistic models that explain the biophysical interactions underlying seizures. It is also possible to use these approaches to model and analyse the interactions between different regions of the brain (In this case the notion of network plays an important role) and the transition to ictal state. These large-scale approaches have the advantage of being able to be related to the recordings made in humans thanks to electroencephalography (EEG). It offers new directions for clinical research, particularly as an additional tool in the treatment of refractory epilepsy
Other approaches are to use the models to try to understand the mechanisms underlying these seizures using biophysical descriptions from the neuron scale. This makes it possible to understand the role of homeostasis and to understand the link between physical quantities (such as the concentration of potassium for example) and the pathological dynamics observed.
This area of research has evolved rapidly in recent years and continues to show promise for our understanding and treatment of epilepsies for either for direct clinical application in the |
https://en.wikipedia.org/wiki/Heston%20model | In finance, the Heston model, named after Steven L. Heston, is a mathematical model that describes the evolution of the volatility of an underlying asset. It is a stochastic volatility model: such a model assumes that the volatility of the asset is not constant, nor even deterministic, but follows a random process.
Basic Heston model
The basic Heston model assumes that St, the price of the asset, is determined by a stochastic process,
where , the instantaneous variance, is given by a Feller square-root or CIR process,
and are Wiener processes (i.e., continuous random walks) with correlation ρ.
The model has five parameters:
, the initial variance.
, the long variance, or long-run average variance of the price; as t tends to infinity, the expected value of νt tends to θ.
, the correlation of the two Wiener processes.
, the rate at which νt reverts to θ.
, the volatility of the volatility, or 'vol of vol', which determines the variance of νt.
If the parameters obey the following condition (known as the Feller condition) then the process is strictly positive
Risk-neutral measure
See Risk-neutral measure for the complete article
A fundamental concept in derivatives pricing is the risk-neutral measure; this is explained in further depth in the above article. For our purposes, it is sufficient to note the following:
To price a derivative whose payoff is a function of one or more underlying assets, we evaluate the expected value of its discounted payoff under a risk-neutral measure.
A risk-neutral measure, also known as an equivalent martingale measure, is one which is equivalent to the real-world measure, and which is arbitrage-free: under such a measure, the discounted price of each of the underlying assets is a martingale. See Girsanov's theorem.
In the Black-Scholes and Heston frameworks (where filtrations are generated from a linearly independent set of Wiener processes alone), any equivalent measure can be described in a very loose sense by adding a |
https://en.wikipedia.org/wiki/Medical%20case%20management | Medical case management is a collaborative process that facilitates recommended treatment plans to assure the appropriate medical care is provided to disabled, ill or injured individuals. It is a role frequently overseen by patient advocates.
It refers to the planning and coordination of health care services appropriate to achieve the goal of medical rehabilitation. Medical case management may include, but is not limited to, care assessment, including personal interview with the injured employee, and assistance in developing, implementing and coordinating a medical care plan with health care providers, as well as the employee and his/her family and evaluation of treatment results.
Medical case management requires the evaluation of a medical condition, developing and implementing a plan of care, coordinating medical resources, communicated healthcare needs to the individual, monitors an individual's progress and promotes cost-effective care.
The term also has usage in the USA health care system, referring to the case management coordination in the managed care environment.
See also
Case management (mental health)
Disease management (health)
Case management (US healthcare system) |
https://en.wikipedia.org/wiki/Kilroy%20was%20here | Kilroy was here is a meme that became popular during World War II, typically seen in graffiti. Its origin is debated, but the phrase and the distinctive accompanying doodle became associated with GIs in the 1940s: a bald-headed man (sometimes depicted as having a few hairs) with a prominent nose peeking over a wall with his fingers clutching the wall.
"Mr Chad" or just "Chad" was the version that became popular in the United Kingdom. The character of Chad may have been derived from a British cartoonist in 1938, possibly pre-dating "Kilroy was here". According to Dave Wilton, "Some time during the war, Chad and Kilroy met, and in the spirit of Allied unity merged, with the British drawing appearing over the American phrase." Other names for the character include Smoe, Clem, Flywheel, Private Snoops, Overby, Eugene the Jeep, Scabooch, and Sapo.
According to Charles Panati, "The outrageousness of the graffiti was not so much what it said, but where it turned up." It is not known if there was an actual person named Kilroy who inspired the graffiti, although there have been claims over the years.
Origin and use of the phrase
The phrase may have originated through United States servicemen who would draw the picture and the text "Kilroy was here" on the walls and other places where they were stationed, encamped, or visited. An ad in Life magazine noted that WWII-era servicemen were fond of claiming that "whatever beach-head they stormed, they always found notices chalked up ahead of them, that 'Kilroy was here. Brewer's Dictionary of Phrase and Fable notes that it was particularly associated with the Air Transport Command, at least when observed in the United Kingdom. At some point, the graffiti (Chad) and slogan (Kilroy was here) must have merged.
Many sources claim origin as early as 1939. Earlier examples of the phrase dating from 1937 are unverified.
According to one story, German intelligence found the phrase on captured American equipment. This led Adolf Hit |
https://en.wikipedia.org/wiki/Employee%20scheduling%20software | Employee scheduling software automates the process of creating and maintaining a schedule. Automating the scheduling of employees increases productivity and allows organizations with hourly workforces to re-allocate resources to non-scheduling activities. Such software will usually track vacation time, sick time, compensation time, and alert when there are conflicts. As scheduling data is accumulated over time, it may be extracted for payroll or to analyze past activity. Although employee scheduling software may or may not make optimization decisions, it does manage and coordinate the tasks. Today's employee scheduling software often includes mobile applications. Mobile scheduling further increased scheduling productivity and eliminated inefficient scheduling steps. It may also include functionality including applicant tracking and on-boarding, time and attendance, and automatic limits on overtime. Such functionality can help organizations with issues like employee retention, compliance with labor laws, and other workforce management challenges.
Purpose
A theoretical underpinning of an employee scheduling problem can be represented as the Nurse scheduling problem, which is NP-hard. The theoretical complexity of the problem is a significant factor in the development of various software solutions. This is because systems must take into account many different forms of schedules that could be worked, and allocate employees to the correct schedule. Ultimately, optimization of scheduling is to minimize costs, but also often requires a reciprocal approach from management instead of complete reliance on software.
Transitioning to employee scheduling software
Prior to employee scheduling software companies would use physical mediums for tracking employee hours and work schedule. This then gave rise to data storage forms that later by the 80s were compatible with computer programs and software. These forms however never actually scheduled the employees, it just kept track |
https://en.wikipedia.org/wiki/List%20of%20Moroccan%20flags | List of Moroccan flags This is a list of flags used in Morocco. For more information about the national flag, visit the article Flag of Morocco.
National Flags
Royal Standard
Military Flags
Historical flags
French Morocco
Spanish Morocco
Republic of the Rif
Tangier International Zone
Regional flags
Sources
External links
Lists and galleries of flags
Flags
Flags |
https://en.wikipedia.org/wiki/Requirements%20engineering | Requirements engineering (RE) is the process of defining, documenting, and maintaining requirements in the engineering design process. It is a common role in systems engineering and software engineering.
The first use of the term requirements engineering was probably in 1964 in the conference paper "Maintenance, Maintainability, and System Requirements Engineering", but it did not come into general use until the late 1990s with the publication of an IEEE Computer Society tutorial in March 1997 and the establishment of a conference series on requirements engineering that has evolved into the International Requirements Engineering Conference.
In the waterfall model, requirements engineering is presented as the first phase of the development process. Later development methods, including the Rational Unified Process (RUP) for software, assume that requirements engineering continues through a system's lifetime.
Requirements management, which is a sub-function of Systems Engineering practices, is also indexed in the International Council on Systems Engineering (INCOSE) manuals.
Activities
The activities involved in requirements engineering vary widely, depending on the type of system being developed and the organization's specific practice(s) involved. These may include:
Requirements inception or requirements elicitation – Developers and stakeholders meet; the latter are inquired concerning their needs and wants regarding the software product.
Requirements analysis and negotiation – Requirements are identified (including new ones if the development is iterative), and conflicts with stakeholders are solved. Both written and graphical tools (the latter commonly used in the design phase, but some find them helpful at this stage, too) are successfully used as aids. Examples of written analysis tools: use cases and user stories. Examples of graphical tools: UML and LML.
System modeling – Some engineering fields (or specific situations) require the product to be completel |
https://en.wikipedia.org/wiki/Rule%20184 | Rule 184 is a one-dimensional binary cellular automaton rule, notable for solving the majority problem as well as for its ability to simultaneously describe several, seemingly quite different, particle systems:
Rule 184 can be used as a simple model for traffic flow in a single lane of a highway, and forms the basis for many cellular automaton models of traffic flow with greater sophistication. In this model, particles (representing vehicles) move in a single direction, stopping and starting depending on the cars in front of them. The number of particles remains unchanged throughout the simulation. Because of this application, Rule 184 is sometimes called the "traffic rule".
Rule 184 also models a form of deposition of particles onto an irregular surface, in which each local minimum of the surface is filled with a particle in each step. At each step of the simulation, the number of particles increases. Once placed, a particle never moves.
Rule 184 can be understood in terms of ballistic annihilation, a system of particles moving both leftwards and rightwards through a one-dimensional medium. When two such particles collide, they annihilate each other, so that at each step the number of particles remains unchanged or decreases.
The apparent contradiction between these descriptions is resolved by different ways of associating features of the automaton's state with particles.
The name of Rule 184 is a Wolfram code that defines the evolution of its states. The earliest research on Rule 184 is by and . In particular, Krug and Spohn already describe all three types of particle system modeled by Rule 184.
Definition
A state of the Rule 184 automaton consists of a one-dimensional array of cells, each containing a binary value (0 or 1). In each step of its evolution, the Rule 184 automaton applies the following rule to each of the cells in the array, simultaneously for all cells, to determine the new state of the cell:
An entry in this table defines the new state of |
https://en.wikipedia.org/wiki/Association%20scheme | The theory of association schemes arose in statistics, in the theory of experimental design for the analysis of variance. In mathematics, association schemes belong to both algebra and combinatorics. In algebraic combinatorics, association schemes provide a unified approach to many topics, for example combinatorial designs and the theory of error-correcting codes. In algebra, association schemes generalize groups, and the theory of association schemes generalizes the character theory of linear representations of groups.
Definition
An n-class association scheme consists of a set X together with a partition S of X × X into n + 1 binary relations, R0, R1, ..., Rn which satisfy:
; it is called the identity relation.
Defining , if R in S, then R* in S.
If , the number of such that and is a constant depending on , , but not on the particular choice of and .
An association scheme is commutative if for all , and . Most authors assume this property.
A symmetric association scheme is one in which each is a symmetric relation. That is:
if (x, y) ∈ Ri, then (y, x) ∈ Ri. (Or equivalently, R* = R.)
Every symmetric association scheme is commutative.
Note, however, that while the notion of an association scheme generalizes the notion of a group, the notion of a commutative association scheme only generalizes the notion of a commutative group.
Two points x and y are called i th associates if . The definition states that if x and y are i th associates then so are y and x. Every pair of points are i th associates for exactly one . Each point is its own zeroth associate while distinct points are never zeroth associates. If x and y are k th associates then the number of points which are both i th associates of and j th associates of is a constant .
Graph interpretation and adjacency matrices
A symmetric association scheme can be visualized as a complete graph with labeled edges. The graph has vertices, one for each point of , and the edge joining vertices a |
https://en.wikipedia.org/wiki/South%20African%20wireless%20community%20networks | South African wireless community networks are wireless networks that allow members to talk, send messages, share files and play games independent of the commercial landline and mobile telephone networks. Most of them use WiFi technology and many are wireless mesh networks. A wireless community network may connect to the public switched telephone network and/or the Internet, but there are various restrictions on connectivity in South Africa. Wireless community networks are particularly useful in areas where commercial telecommunications services are unavailable or unaffordable.
Wireless User Groups (WUGs) in South African cities build up infrastructure and applications, as well as training members in wireless technology skills. Therefore, WUGs provide a fertile ground for new technology and applications that may have large social benefits in informal communities and rural areas of South Africa and neighboring countries.
Background: South African Telecommunications Environment
South Africa has the best developed and most modern telephone system in Africa. There are almost 110 combined fixed-line and cellular telephones per 100 persons. There are 5.1 million Internet users. The network is 99.9% digital. The fixed-line monopoly of Telkom SA, a listed company in which the government is the largest shareholder, expired with the licensing of Neotel as South Africa's second national operator, starting operations in November 2007. Neotel is licensed to provide the entire range of telecoms services with the exception of full mobility. Neotel is expanding their network fast, but so far is concentrating on urban areas. The South African mobile communications market is growing fast. The country's three cellular network operators (Vodacom, MTN and Cell C) have over 39-million subscribers, or nearly 80% of the population.
However, although there are now over one million broadband subscribers, mostly using ADSL or HSDPA,
bandwidth remains relatively limited and expensive. Majo |
https://en.wikipedia.org/wiki/Bessel%27s%20correction | In statistics, Bessel's correction is the use of n − 1 instead of n in the formula for the sample variance and sample standard deviation, where n is the number of observations in a sample. This method corrects the bias in the estimation of the population variance. It also partially corrects the bias in the estimation of the population standard deviation. However, the correction often increases the mean squared error in these estimations. This technique is named after Friedrich Bessel.
Formulation
In estimating the population variance from a sample when the population mean is unknown, the uncorrected sample variance is the mean of the squares of deviations of sample values from the sample mean (i.e. using a multiplicative factor 1/n). In this case, the sample variance is a biased estimator of the population variance.
Multiplying the uncorrected sample variance by the factor
gives an unbiased estimator of the population variance. In some literature, the above factor is called Bessel's correction.
One can understand Bessel's correction as the degrees of freedom in the residuals vector (residuals, not errors, because the population mean is unknown):
where is the sample mean. While there are n independent observations in the sample, there are only n − 1 independent residuals, as they sum to 0. For a more intuitive explanation of the need for Bessel's correction, see .
Generally Bessel's correction is an approach to reduce the bias due to finite sample size. Such finite-sample bias correction is also needed for other estimates like skew and kurtosis, but in these the inaccuracies are often significantly larger. To fully remove such bias it is necessary to do a more complex multi-parameter estimation. For instance a correct correction for the standard deviation depends on the kurtosis (normalized central 4th moment), but this again has a finite sample bias and it depends on the standard deviation, i.e. both estimations have to be merged.
Caveats
There are thr |
https://en.wikipedia.org/wiki/Copper%28I%29%20oxide | Copper(I) oxide or cuprous oxide is the inorganic compound with the formula Cu2O. It is one of the principal oxides of copper, the other being or copper(II) oxide or cupric oxide (CuO). Cuprous oxide is a red-coloured solid and is a component of some antifouling paints. The compound can appear either yellow or red, depending on the size of the particles. Copper(I) oxide is found as the reddish mineral cuprite.
Preparation
Copper(I) oxide may be produced by several methods.<ref>H. Wayne Richardson "Copper Compounds in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. </ref> Most straightforwardly, it arises via the oxidation of copper metal:
4 Cu + O2 → 2 Cu2O
Additives such as water and acids affect the rate of this process as well as the further oxidation to copper(II) oxides. It is also produced commercially by reduction of copper(II) solutions with sulfur dioxide.
Reactions
Aqueous cuprous chloride solutions react with base to give the same material. In all cases, the color is highly sensitive to the procedural details.
Formation of copper(I) oxide is the basis of the Fehling's test and Benedict's test for reducing sugars. These sugars reduce an alkaline solution of a copper(II) salt, giving a bright red precipitate of Cu2O.
It forms on silver-plated copper parts exposed to moisture when the silver layer is porous or damaged. This kind of corrosion is known as red plague.
Little evidence exists for copper(I) hydroxide CuOH, which is expected to rapidly undergo dehydration. A similar situation applies to the hydroxides of gold(I) and silver(I).
Properties
The solid is diamagnetic. In terms of their coordination spheres, copper centres are 2-coordinated and the oxides are tetrahedral. The structure thus resembles in some sense the main polymorphs of SiO2, but cuprous oxide's lattices interpenetrate.
Copper(I) oxide dissolves in concentrated ammonia solution to form the colourless complex [Cu(NH3)2]+, which is easily o |
https://en.wikipedia.org/wiki/Pseudo-panspermia | Pseudo-panspermia (sometimes called soft panspermia, molecular panspermia or quasi-panspermia) is a well-supported hypothesis for a stage in the origin of life. The theory first asserts that many of the small organic molecules used for life originated in space (for example, being incorporated in the solar nebula, from which the planets condensed). It continues that these organic molecules were distributed to planetary surfaces, where life then emerged on Earth and perhaps on other planets. Pseudo-panspermia differs from the fringe theory of panspermia, which asserts that life arrived on Earth from distant planets.
Background
Theories of the origin of life have been current since the 5th century BC, when the Greek philosopher Anaxagoras proposed an initial version of panspermia: life arrived on earth from the heavens. In modern times, panspermia has little support amongst mainstream scientists.
Extraterrestrial creation of organic molecules
Interstellar molecules are formed by chemical reactions within very sparse interstellar or circumstellar clouds of dust and gas. Usually this occurs when a molecule becomes ionised, often as the result of an interaction with cosmic rays. This positively charged molecule then draws in a nearby reactant by electrostatic attraction of the neutral molecule's electrons. Molecules can also be generated by reactions between neutral atoms and molecules, although this process is generally slower. The dust plays a critical role of shielding the molecules from the ionizing effect of ultraviolet radiation emitted by stars. The Murchison meteorite contains the organic molecules uracil and xanthine, which must therefore already have been present in the early Solar System, where they could have played a role in the origin of life.
Nitriles, key molecular precursors of the RNA World scenario, are among the most abundant chemical families in the universe and have been found in molecular clouds in the center of the Milky Way, protostars of di |
https://en.wikipedia.org/wiki/George%20Emil%20Palade | George Emil Palade (; November 19, 1912 – October 7, 2008) was a Romanian-American cell biologist. Described as "the most influential cell biologist ever", in 1974 he was awarded the Nobel Prize in Physiology and Medicine along with Albert Claude and Christian de Duve. The prize was granted for his innovations in electron microscopy and cell fractionation which together laid the foundations of modern molecular cell biology, the most notable discovery being the ribosomes of the endoplasmic reticulum – which he first described in 1955.
Palade also received the U.S. National Medal of Science in Biological Sciences for "pioneering discoveries of a host of fundamental, highly organized structures in living cells" in 1986, and was previously elected a Member of the US National Academy of Sciences in 1961. In 1968 he was elected as an Honorary Fellow of the Royal Microscopical Society (HonFRMS) and in 1984 he became a Foreign Member of the Royal Society (ForMemRS).
Education and early life
George Emil Palade was born on November 19, 1912, in Iași, Romania; his father was a professor of philosophy at the University of Iași and his mother was a high school teacher. Palade received his M.D. in 1940 from the Carol Davila School of Medicine in Bucharest.
Career and research
Palade was a member of the faculty at Carol Davila University until 1946, when he went to the United States to do postdoctoral research. While assisting Robert Chambers in the Biology Laboratory of New York University, he met Professor Albert Claude. He later joined Claude at the Rockefeller Institute for Medical Research.
In 1952, Palade became a naturalized citizen of the United States. He worked at the Rockefeller Institute (1958–1973), and was a professor at Yale University Medical School (1973–1990), and University of California, San Diego (1990–2008). At UCSD, Palade was Professor of Medicine in Residence (Emeritus) in the Department of Cellular & Molecular Medicine, as well as a Dean for Scienti |
https://en.wikipedia.org/wiki/Evolutionary%20medicine | Evolutionary medicine or Darwinian medicine is the application of modern evolutionary theory to understanding health and disease. Modern biomedical research and practice have focused on the molecular and physiological mechanisms underlying health and disease, while evolutionary medicine focuses on the question of why evolution has shaped these mechanisms in ways that may leave us susceptible to disease. The evolutionary approach has driven important advances in the understanding of cancer, autoimmune disease, and anatomy. Medical schools have been slower to integrate evolutionary approaches because of limitations on what can be added to existing medical curricula. The International Society for Evolution, Medicine and Public Health coordinates efforts to develop the field. It owns the Oxford University Press journal Evolution, Medicine and Public Health and The Evolution and Medicine Review.
Core principles
Utilizing the Delphi method, 56 experts from a variety of disciplines, including anthropology, medicine, nursing, and biology agreed upon 14 core principles intrinsic to the education and practice of evolutionary medicine. These 14 principles can be further grouped into five general categories: question framing, evolution I and II (with II involving a higher level of complexity), evolutionary trade-offs, reasons for vulnerability, and culture. Additional information regarding these principles may be found in the table below.
Human adaptations
Adaptation works within constraints, makes compromises and trade-offs, and occurs in the context of different forms of competition.
Constraints
Adaptations can only occur if they are evolvable. Some adaptations which would prevent ill health are therefore not possible.
DNA cannot be totally prevented from undergoing somatic replication corruption; this has meant that cancer, which is caused by somatic mutations, has not (so far) been eliminated by natural selection.
Humans cannot biosynthesize vitamin C, and so risk |
https://en.wikipedia.org/wiki/Transverse%20humeral%20ligament | The transverse humeral ligament (Brodie's ligament) forms a broad band bridging the lesser and greater tubercle of the humerus. Its attachments are limited superior to the epiphysial line. By enclosing the canal of the bicipital groove (intertubercular groove), it functions to hold the long head of the biceps tendon within the bicipital groove. |
https://en.wikipedia.org/wiki/Trochlear%20nerve | The trochlear nerve (), (lit. pulley-like nerve) also known as the fourth cranial nerve, cranial nerve IV, or CN IV, is a cranial nerve that innervates a single muscle - the superior oblique muscle of the eye (which operates through the pulley-like trochlea). Unlike most other cranial nerves, the trochlear nerve is exclusively a motor nerve (somatic efferent nerve).
The trochlear nerve is unique among the cranial nerves in several respects:
It is the smallest nerve in terms of the number of axons it contains.
It has the greatest intracranial length.
It is the only cranial nerve that exits from the dorsal (rear) aspect of the brainstem.
It innervates a muscle, the superior oblique muscle, on the opposite side (contralateral) from its nucleus. The trochlear nerve decussates within the brainstem before emerging on the contralateral side of the brainstem (at the level of the inferior colliculus). An injury to the trochlear nucleus in the brainstem will result in an contralateral superior oblique muscle palsy, whereas an injury to the trochlear nerve (after it has emerged from the brainstem) results in an ipsilateral superior oblique muscle palsy.
The superior oblique muscle which the trochlear nerve innervates ends in a tendon that passes through a fibrous loop, the trochlea, located anteriorly on the medial aspect of the orbit. Trochlea means “pulley” in Latin; the fourth nerve is thus also named after this structure. The words trochlea and trochlear (, ) come from Ancient Greek trokhiléa, “pulley; block-and-tackle equipment”.
Structure
The trochlear nerve provides motor innervation to the superior oblique muscle of the eye, a skeletal muscle; the trochlear nerve thus carries axons of general somatic efferent type.
Course
Each trochlear nerve originates from a trochlear nucleus in the medial midbrain. From their respective nuclei, the two trochlear nerves then travel dorsal-ward through the substance of the midbrain surrounded by the periaqueductal gray, |
https://en.wikipedia.org/wiki/Batch%20cryptography | Batch cryptography is the area of cryptology where cryptographic protocols are studied and developed for doing cryptographic processes like encryption/decryption, key exchange, authentication, etc. in a batch way instead of one by one. The concept of batch cryptography was introduced by Amos Fiat in 1989. |
https://en.wikipedia.org/wiki/Momentum%20map | In mathematics, specifically in symplectic geometry, the momentum map (or, by false etymology, moment map) is a tool associated with a Hamiltonian action of a Lie group on a symplectic manifold, used to construct conserved quantities for the action. The momentum map generalizes the classical notions of linear and angular momentum. It is an essential ingredient in various constructions of symplectic manifolds, including symplectic (Marsden–Weinstein) quotients, discussed below, and symplectic cuts and sums.
Formal definition
Let M be a manifold with symplectic form ω. Suppose that a Lie group G acts on M via symplectomorphisms (that is, the action of each g in G preserves ω). Let be the Lie algebra of G, its dual, and
the pairing between the two. Any ξ in induces a vector field ρ(ξ) on M describing the infinitesimal action of ξ. To be precise, at a point x in M the vector is
where is the exponential map and denotes the G-action on M. Let denote the contraction of this vector field with ω. Because G acts by symplectomorphisms, it follows that is closed (for all ξ in ).
Suppose that is not just closed but also exact, so that for some function . If this holds, then one may choose the to make the map linear. A momentum map for the G-action on (M, ω) is a map such that
for all ξ in . Here is the function from M to R defined by . The momentum map is uniquely defined up to an additive constant of integration (on each connected component).
An -action on a symplectic manifold is called Hamiltonian if it is symplectic and if there exists a momentum map.
A momentum map is often also required to be -equivariant, where G acts on via the coadjoint action, and sometimes this requirement is included in the definition of a Hamiltonian group action. If the group is compact or semisimple, then the constant of integration can always be chosen to make the momentum map coadjoint equivariant. However, in general the coadjoint action must be modified to make the map |
https://en.wikipedia.org/wiki/Digital%20Rights%20Ireland | Digital Rights Ireland is a digital rights advocacy and lobbying group based in Ireland. The group works for civil liberties in a digital age.
Telecommunications data retention
In 2012, the group brought an action before the Irish High Court, which subsequently made a reference to the Court of Justice of the European Union to take legal action over telecommunications data retention provided for by the Criminal Justice (Terrorist Offences) Act of 2005.
Digital Rights Ireland argues that the act led to Gardaí accessing retained data without having a specific crime to investigate, citing remarks by the Data Protection Commissioner.
On 8 April 2014, the Court of Justice of the European Union declared the Directive invalid in response to a case brought by Digital Rights Ireland against the Irish authorities and others.
File sharing
The Irish Recorded Music Association has sent letters to people it accuses of file sharing their music, demanding damages for financial losses. One issue is how the files belonging to the alleged file-sharers were searched. MediaSentry software was used to search their machines, but as it doesn't limit itself to searching only folders used for file sharing, this led to questions of violation of privacy. MediaSentry itself is based in the United States, which has less legislation about data protection than the European Union. This has been an issue in cases in the Netherlands and France.
Another issue is Internet service providers being compelled to identify users.
Current action still causes concern to DRI.
Former TD Dr. Jerry Cowley has requested that the complaints referee investigate whether his telephone is being tapped. DRI expressed concern, noting that there is no Irish equivalent of the Wilson Doctrine in Irish law. Fine Gael has also shown concern at the number of telephone taps authorised by former Minister for Justice Michael McDowell. DRI said that the reasons for withholding the information was unacceptable.
Other areas |
https://en.wikipedia.org/wiki/Bifurcation%20locus | In complex dynamics, the bifurcation locus of a parameterized family of one-variable holomorphic functions informally is a locus of those parameterized points for which the dynamical behavior changes drastically under a small perturbation of the parameter. Thus the bifurcation locus can be thought of as an analog of the Julia set in parameter space. Without doubt, the most famous example of a bifurcation locus is the boundary of the Mandelbrot set.
Parameters in the complement of the bifurcation locus are called J-stable. |
https://en.wikipedia.org/wiki/Vespertine%20%28biology%29 | Vespertine is a term used in the life sciences to indicate something of, relating to, or occurring in the evening. In botany, a vespertine flower is one that opens or blooms in the evening. In zoology, the term is used for a creature that becomes active at dusk, such as bats and owls. Strictly speaking, however, the term means that activity ceases during the hours of full darkness and does not resume until the next evening. Activity that continues throughout the night should be described as nocturnal.
Vespertine behaviour is a special case of crepuscular behaviour; like crepuscular activity, vespertine activity is limited to dusk rather than full darkness. Unlike vespertine activity, crepuscular activity may resume in dim twilight before dawn. A related term is matutinal, referring to activity limited to the dawn twilight.
The word vespertine is derived from the Latin word , an adjective meaning "evening".
See also
Crypsis
Matutinal |
https://en.wikipedia.org/wiki/Choanosome | A choanosome is an inner region of a sponge, supported on the choanoskeleton, the structure that contains the choanocytes.
See also
Choanoderm
Sponge anatomy |
https://en.wikipedia.org/wiki/Thermodesulfobacteriota | The Thermodesulfobacteriota are a phylum of thermophilic sulfate-reducing bacteria.
A pathogenic intracellular thermodesulfobacteriote has recently been identified.
Phylogeny
The phylogeny is based on phylogenomic analysis:
See also
List of bacterial orders
List of bacteria genera |
https://en.wikipedia.org/wiki/New%20Brunswick%20neurological%20syndrome%20of%20unknown%20cause | A neurological syndrome of unknown cause was identified as a potential novel degenerative disease in a cluster of individuals with similar clinical signs and symptoms in the Canadian province of New Brunswick beginning in 2019. Symptoms listed on the New Brunswick Public Health (NBPH) website include memory problems, muscle spasms, balance problems, difficulty walking or falls, blurred vision or visual hallucinations, unexplained or significant weight loss, behaviour changes, and pain in the upper or lower limbs.
Background
The investigation into the cluster was instigated in 2019 at the federal level by the Ottawa-based Creutzfeldt-Jakob Disease Surveillance System (CJDSS) unit – which operates under Public Health Agency of Canada (PHAC). CJDSS director Michael Coulthart worked with Alier Marrero, a neurologist at Dr. Georges-L.-Dumont University Hospital Centre, in Moncton, New Brunswick who had referred cases to the CJDSS unit for testing and diagnosis. The disease cluster was first noted through the routine case management arrangement between New Brunswick and federal health authorities, when experts from the CJDSS unit – which provides surveillance for "all types of human prion disease in Canada" – noticed a significant number of NB referrals had "some common symptoms and similar potential diagnostic profiles". The CJDSS ruled out any prion disorder, including Creutzfeldt-Jakob Disease (CJD) – an incurable, fatal disease. Marrero and Coulthart and colleagues worked for months together investigating the cases. The federal-provincial team began to suspect that they were looking at a novel neurological degenerative disease potentially caused by a toxin or agent. By December 2020, 24 new cases in New Brunswick of something that "looked like CJD but was not" had been diagnosed. PHAC considered this to be an "unusually high number" and contacted New Brunswick's Chief Medical Officer of Health (CMOH) Jennifer Russell, about the disease cluster. In January 2021, the |
https://en.wikipedia.org/wiki/Action%20potential%20pulse | An action potential pulse is a mathematically and experimentally correct Synchronized Oscillating Lipid Pulse coupled with an Action Potential. This is a continuation of Hodgkin Huxley's work in 1952 with the inclusion of accurately modelling ion channel proteins, including their dynamics and speed of activation.
The action potential pulse is a model of the speed an action potential that is dynamically dependent upon the position and number of ion channels, and the shape and make up of the axon. The action potential pulse model takes into account entropy and the conduction speed of the action potential along an axon. It is an addition to the Hodgkin Huxley model.
Investigation into the membranes of axons have shown that the spaces in between the channels are sufficiently large, such that cable theory cannot apply to them, because it depends upon the capacitance potential of a membrane to be transferred almost instantly to other areas of the membrane surface. In electrical circuits this can happen because of the special properties of electrons, which are negatively charged, whereas in membrane biophysics potential is defined by positively charged ions instead. These ions are usually Na1+ or Ca2+, which move slowly by diffusion and have limited ionic radii in which they can affect adjacent ion channels. It is mathematically impossible for these positive ions to move from one channel to the next, in the time required by the action potential flow model, due to instigated depolarization. Furthermore entropy measurements have long demonstrated that an action potential's flow starts with a large increase in entropy followed by a steadily decreasing state, which does not match the Hodgkin Huxley theory. In addition a soliton pulse is known to flow at the same rate and follow the action potential. From measurements of the speed of an action potential, hyperpolarization must have a further component of which the 'soliton' mechanical pulse is the only candidate.
The resulti |
https://en.wikipedia.org/wiki/Manhattan%20wiring | Manhattan wiring (also known as right-angle wiring) is a technique for laying out circuits in computer engineering. Inputs to a circuit (specifically, the interconnects from the inputs) are aligned into a grid, and the circuit "taps" (connects to) them perpendicularly. This may be done either virtually or physically. That is, it may be shown this way only in the documentation and the actual circuit may look nothing like that; or it may be laid out that way on the physical chip. Typically, separate lanes are used for the inverted inputs and are tapped separately.
The name Manhattan wiring relates to its Manhattan geometry. Reminiscent of how streets in Manhattan, New York tend to criss-cross in a very regular grid, it relates to appearance of such circuit diagrams.
Manhattan wiring is often used to represent a programmable logic array.
Alternatives include X-architecture wiring, or 45° wiring, and Y-architecture wiring (using wires running in the 0°, 120°, and 240° directions).
See also
Manhattan metric |
https://en.wikipedia.org/wiki/INTERBUS | INTERBUS is a serial bus system which transmits data between control systems (e.g., PCs, PLCs, VMEbus computers, robot controllers etc.) and spatially distributed I/O modules that are connected to sensors and actuators (e.g., temperature sensors, position switches).
The INTERBUS system was developed by Phoenix Contact and has been available since 1987. It is one of the leading Fieldbus systems in the automation industry and is fully standardized according to European Standard EN 50254 and IEC 61158.
At the moment, more than 600 manufacturers are involved in the implementation of INTERBUS technology in control systems and field devices.
Since 2011 is the INTERBUS technology hosted by the industry association Profibus and Profinet International.
See also
BiSS interface
External links
www.interbusclub.com
www.phoenixcontact.com
Explanation of Bit-based Sensor networks including SeriPlex
Serial buses
Industrial computing
Industrial automation |
https://en.wikipedia.org/wiki/Wi-Fi%20Protected%20Access | Wi-Fi Protected Access (WPA), Wi-Fi Protected Access 2 (WPA2), and Wi-Fi Protected Access 3 (WPA3) are the three security certification programs developed after 2000 by the Wi-Fi Alliance to secure wireless computer networks. The Alliance defined these in response to serious weaknesses researchers had found in the previous system, Wired Equivalent Privacy (WEP).
WPA (sometimes referred to as the TKIP standard) became available in 2003. The Wi-Fi Alliance intended it as an intermediate measure in anticipation of the availability of the more secure and complex WPA2, which became available in 2004 and is a common shorthand for the full IEEE 802.11i (or IEEE 802.11i-2004) standard.
In January 2018, the Wi-Fi Alliance announced the release of WPA3, which has several security improvements over WPA2.
As of 2023, most computers that connect to a wireless network have support for using WPA, WPA2, or WPA3.
Versions
WPA
The Wi-Fi Alliance intended WPA as an intermediate measure to take the place of WEP pending the availability of the full IEEE 802.11i standard. WPA could be implemented through firmware upgrades on wireless network interface cards designed for WEP that began shipping as far back as 1999. However, since the changes required in the wireless access points (APs) were more extensive than those needed on the network cards, most pre-2003 APs could not be upgraded to support WPA.
The WPA protocol implements the Temporal Key Integrity Protocol (TKIP). WEP used a 64-bit or 128-bit encryption key that must be manually entered on wireless access points and devices and does not change. TKIP employs a per-packet key, meaning that it dynamically generates a new 128-bit key for each packet and thus prevents the types of attacks that compromised WEP.
WPA also includes a Message Integrity Check, which is designed to prevent an attacker from altering and resending data packets. This replaces the cyclic redundancy check (CRC) that was used by the WEP standard. CRC's main fl |
https://en.wikipedia.org/wiki/Token%20reconfiguration | In computational complexity theory and combinatorics, the token reconfiguration problem is a reconfiguration problem on a graph with both an initial and desired state for tokens.
Given a graph , an initial state of tokens is defined by a subset of the vertices of the graph; let . Moving a token from vertex to vertex is valid if and are joined by a path in that does not contain any other tokens; note that the distance traveled within the graph is inconsequential, and moving a token across multiple edges sequentially is considered a single move. A desired end state is defined as another subset . The goal is to minimize the number of valid moves to reach the end state from the initial state.
Motivation
The problem is motivated by so-called sliding puzzles, which are in fact a variant of this problem, often restricted to rectangular grid graphs with no holes. The most famous such puzzle, the 15 puzzle, is a variant of this problem on a 4 by 4 grid graph such that . One key difference between sliding block puzzles and the token reconfiguration problem is that in the original token reconfiguration problem, the tokens are indistinguishable. As a result, if the graph is connected, the token reconfiguration problem is always solvable; this is not necessarily the case for sliding block puzzles.
Complexity
Calinescu, Dumitrescu, and Pach have shown several results regarding both the optimization and approximation of this problem on various types of graphs.
Optimization
Firstly, reducing to the case of trees, there is always a solution in at most moves, with at most one move per token. Furthermore, an optimal solution can be found in time linear in the size of the tree. Clearly, the first result extends to arbitrary graphs; the latter does not.
A sketch of the optimal algorithm for trees is as follows. First, we obtain an algorithm that moves each node exactly once, which may not be optimal. Do this recursively: consider any leaf of the smallest tree |
https://en.wikipedia.org/wiki/BigCommerce | BigCommerce is a NASDAQ-listed ecommerce platform that provides software as a service services to retailers. The company's platform includes online store creation, search engine optimization, hosting, and marketing and security from small to Enterprise sized businesses.
History
BigCommerce was founded in Sydney, Australia in 2009 by Australians Eddie Machaalani and Mitchell Harper, who met in an online chatroom in 2003. One year after meeting, Machaalani and Harper launched their first company, Interspire, which evolved into BigCommerce. The company opened its first United States office in Austin, Texas in 2009.
The company raised $15 million in Series A funding from General Catalyst in July 2011.
In 2014, the company expanded its presence on the West Coast, opening a San Francisco office and hiring personnel from PayPal and Amazon. In 2015, BigCommerce acquired Zing, a checkout and inventory software startup.
Brent Bellm, the former HomeAway COO who led HomeAway through its IPO, replaced Machaalani and Harper as CEO in 2015.
BigCommerce partnered with Amazon in 2016 to provide its retailers with the capability to sync inventory across both channels.
In 2019, the company opened its ecommerce platforms to legally-operating U.S.-based CBD and hemp merchants.
In July 2020, BigCommerce filed for IPO. The company went public on August 5, 2020.
Services
BigCommerce provides software to businesses that helps them set up and manage online and mobile stores, handle payments and currency conversions.
As of June 2020, BigCommerce served 60,000 online stores in 120 countries.
See also
Comparison of shopping cart software |
https://en.wikipedia.org/wiki/Reinhardt%20Kiehl | Reinhardt Kiehl (born 31 May 1935 in Herne, North Rhine-Westphalia) is a German mathematician.
From 1955, Kiehl studied mathematics, physics and astronomy at the University of Göttingen and the University of Heidelberg. He received in 1965 his Ph.D. (promotion) under Friedrich Karl Schmidt at Heidelberg University with thesis Äquivalenzrelationen in analytischen Räumen. He was from 1966 to 1968 a research assistant and in 1968–1969 a docent at the University of Münster, where he received in 1968 his habilitation. From 1969 to 1972 he was a professor ordinarius at the Goethe-Universität Frankfurt am Main. From 1972 he was a professor ordinarius at the University of Mannheim, where he retired in 2003 as professor emeritus.
His research deals with algebraic and arithmetic geometry and non-archimedean function theory. He wrote with Eberhard Freitag a textbook on the Weil conjectures and étale cohomology. In 1970 Kiehl was an Invited Speaker at the ICM in Nice with talk Grauertsche Kohärenzsätze für stetige und differenzierbare Familien komplexer Räume.
Selected publications
with Eberhard Freitag: Etale Cohomology and the Weil Conjecture, Springer Verlag 1988
with Rainer Weissauer: Weil Conjectures, Perverse Sheaves and ℓ-adic Fourier Transform, Springer Verlag 2001
De Rham Kohomologie algebraischer Mannigfaltigkeiten über einem bewerteten Körper, Pub. Math. IHES, vol. 33, 1967, pp. 5–20, Online
Der Endlichkeitssatz für eigentliche Abbildungen in der nichtarchimedischen Funktionentheorie, Inventiones Mathematicae, vol. 2, 1967, pp. 191–214
Theorem A und B in der nichtarchimedischen Funktionentheorie, Inventiones Mathematicae, vol. 2, 1967, pp. 256–273
Ausgezeichnete Ringe in der nichtarchimedischen analytischen Geometrie, J. Reine Angewandte Mathematik, vol. 235, 1969, p. 89
mit Jean-Louis Verdier Ein einfacher Beweis des Kohärenzsatzes von Grauert, Mathematische Annalen, Band 195, 1971, pp. 24–50
Äquivalenzrelationen in analytischen Räumen, Mathematische Zeitschrift |
https://en.wikipedia.org/wiki/Prenyltransferase | Prenyltransferases (PTs) are a class of enzymes that transfer allylic prenyl groups to acceptor molecules. Prenyl transferases commonly refer to isoprenyl diphosphate syntheses (IPPSs). Prenyltransferases are a functional category and include several enzyme groups that are evolutionarily independent.
Prenyltransferases are commonly divided into two classes, cis (or Z) and trans (or E), depending upon the stereochemistry of the resulting products. Examples of trans-prenyltranferases include dimethylallyltranstransferase, and geranylgeranyl pyrophosphate synthase. Cis-prenyltransferases include dehydrodolichol diphosphate synthase (involved in the production of a precursor to dolichol). Trans- and cis-prenyltransferases are evolutionarily unrelated to each other and there is no sequential and structural similarity.
The beta subunit of the farnesyltransferases is responsible for peptide binding. Squalene-hopene cyclase is a bacterial enzyme that catalyzes the cyclization of squalene into hopene, a key step in hopanoid (triterpenoid) metabolism. Lanosterol synthase () (oxidosqualene-lanosterol cyclase) catalyzes the cyclization of (S)-2,3-epoxysqualene to lanosterol, the initial precursor of cholesterol, steroid hormones and vitamin D in vertebrates and of ergosterol in fungi. Cycloartenol synthase () (2,3-epoxysqualene-cycloartenol cyclase) is a plant enzyme that catalyzes the cyclization of (S)-2,3-epoxysqualene to cycloartenol.
Human proteins containing this domain
FNTB; LSS; PGGT1B; RABGGTB |
https://en.wikipedia.org/wiki/Thermionic%20converter | A thermionic converter consists of a hot electrode which thermionically emits electrons over a potential energy barrier to a cooler electrode, producing a useful electric power output. Caesium vapor is used to optimize the electrode work functions and provide an ion supply (by surface ionization or electron impact ionization in a plasma) to neutralize the electron space charge.
Definition
From a physical electronic viewpoint, thermionic energy conversion is the direct production of electric power from heat by thermionic electron emission. From a thermodynamic viewpoint, it is the use of electron vapor as the working fluid in a power-producing cycle. A thermionic converter consists of a hot emitter electrode from which electrons are vaporized by thermionic emission and a colder collector electrode into which they are condensed after conduction through the inter-electrode plasma. The resulting current, typically several amperes per square centimeter of emitter surface, delivers electrical power to a load at a typical potential difference of 0.5–1 volt and thermal efficiency of 5–20%, depending on the emitter temperature (1500–2000 K) and mode of operation.
History
After the first demonstration of the practical arc-mode caesium vapor thermionic converter by V. Wilson in 1957, several applications of it were demonstrated in the following decade, including its use with solar, combustion, radioisotope, and nuclear reactor heat sources. The application most seriously pursued, however, was the integration of thermionic nuclear fuel elements directly into the core of nuclear reactors for production of electrical power in space. The exceptionally high operating temperature of thermionic converters, which makes their practical use difficult in other applications, gives the thermionic converter decisive advantages over competing energy conversion technologies in the space power application where radiant heat rejection is required. Substantial thermionic space reactor d |
https://en.wikipedia.org/wiki/Colloquium%20Lectures%20%28AMS%29 | The Colloquium Lecture of the American Mathematical Society is a special annual session of lectures.
History
The origins of the Colloquium Lectures date back to the 1893 International Congress of Mathematics, held in connection with the Chicago World's Fair, where the German mathematician Felix Klein gave the opening address. After the Congress, Klein was invited by one of its organiser, his former student Henry Seely White, to deliver a two-week-long series of lectures at Northwestern University in Evanston.
In February 1896, White proposed in a letter to Thomas Fiske to repeat the experience of the Evanston lectures, by organising a series of longer talks "for increasing the utility of the American Mathematical Society". The two of them, together with E. H. Moore, William Osgood, Frank Cole, Alexander Ziwet, and Frank Morley, wrote later an open letter to the AMS, asking the society to sponsor an annual week-long series of Colloquium lectures focussing on a specific mathematical area, in order to complement the traditional shorter talks.
The first official Colloquium Lectures were held in September 1896, after the AMS Summer Meetings in Buffalo, New York, and consisted of two independent series of lectures given by James Pierpont and Maxime Bôcher. A synopse of their lectures was published in the Bulletin of the AMS; starting from the second Colloquium in 1898, the lectures have been published entirely in book form in the AMS Colloquium Publications series.
List of Colloquium Lectures
1896 James Pierpont (Yale University): Galois's theory of equations.
1896 Maxime Bôcher (Harvard University): Linear differential equations and their applications.
1898 William Fogg Osgood (Harvard University): Selected topics in the theory of functions.
1898 Arthur Gordon Webster (Clark University): The partial differential equations of wave propagation.
1901 Oskar Bolza (University of Chicago): The simplest type of problems in the calculus of variations.
1901 Ernest Wi |
https://en.wikipedia.org/wiki/Direct%20sum%20of%20topological%20groups | In mathematics, a topological group is called the topological direct sum of two subgroups and if the map
is a topological isomorphism, meaning that it is a homeomorphism and a group isomorphism.
Definition
More generally, is called the direct sum of a finite set of subgroups of the map
is a topological isomorphism.
If a topological group is the topological direct sum of the family of subgroups then in particular, as an abstract group (without topology) it is also the direct sum (in the usual way) of the family
Topological direct summands
Given a topological group we say that a subgroup is a topological direct summand of (or that splits topologically from ) if and only if there exist another subgroup such that is the direct sum of the subgroups and
A the subgroup is a topological direct summand if and only if the extension of topological groups
splits, where is the natural inclusion and is the natural projection.
Examples
Suppose that is a locally compact abelian group that contains the unit circle as a subgroup. Then is a topological direct summand of The same assertion is true for the real numbers
See also |
https://en.wikipedia.org/wiki/Apollonius%20of%20Perga | Apollonius of Perga ( ; ) was an ancient Greek geometer and astronomer known for his work on conic sections. Beginning from the earlier contributions of Euclid and Archimedes on the topic, he brought them to the state prior to the invention of analytic geometry. His definitions of the terms ellipse, parabola, and hyperbola are the ones in use today. With his predecessors Euclid and Archimedes, Apollonius is generally considered among the greatest mathematicians of antiquity.
Aside from geometry, Apollonius worked on numerous other topics, including astronomy. Most of this work has not survived, where exceptions are typically fragments referenced by other authors like Pappus of Alexandria. His hypothesis of eccentric orbits to explain the apparently aberrant motion of the planets, commonly believed until the Middle Ages, was superseded during the Renaissance. The Apollonius crater on the Moon is named in his honor.
Life
Despite his momentous contributions to the field of mathematics, scant biographical information on Apollonius remains. The 6th century Greek commentator Eutocius of Ascalon, writing on Apollonius' Conics, states:
Apollonius, the geometrician, ... came from Perga in Pamphylia in the times of Ptolemy III Euergetes, so records Herakleios the biographer of Archimedes ....
From this passage Apollonius can be approximately dated, but specific birth and death years stated by modern scholars are only speculative. Ptolemy III Euergetes ("benefactor") was third Greek dynast of Egypt in the Diadochi succession, who reigned 246–222/221 BC. "Times" are always recorded by ruler or officiating magistrate, so Apollonius was likely born after 246. The identity of Herakleios is uncertain.
Perga was a Hellenized city in Pamphylia, Anatolia, whose ruins yet stand. It was a center of Hellenistic culture. Eutocius appears to associate Perga with the Ptolemaic dynasty of Egypt. Never under Egypt, Perga in 246 BC belonged to the Seleucid Empire, an independent diado |
https://en.wikipedia.org/wiki/Model-driven%20security | Model-driven security (MDS) means applying model-driven approaches (and especially the concepts behind model-driven software development) to security.
Development of the concept
The general concept of Model-driven security in its earliest forms has been around since the late 1990s (mostly in university research), and was first commercialized around 2002. There is also a body of later scientific research in this area, which continues to this day.
A more specific definition of Model-driven security specifically applies model-driven approaches to automatically generate technical security implementations from security requirements models. In particular, "Model driven security (MDS) is the tool supported process of modelling security requirements at a high level of abstraction, and using other information sources available about the system (produced by other stakeholders). These inputs, which are expressed in Domain Specific Languages (DSL), are then transformed into enforceable security rules with as little human intervention as possible. MDS explicitly also includes the run-time security management (e.g. entitlements/authorisations), i.e. run-time enforcement of the policy on the protected IT systems, dynamic policy updates and the monitoring of policy violations."
Model-driven security is also well-suited for automated auditing, reporting, documenting, and analysis (e.g. for compliance and accreditation), because the relationships between models and technical security implementations are traceably defined through the model-transformations.
Opinions of industry analysts
Several industry analyst sources state that MDS "will have a significant impact as information security infrastructure is required to become increasingly real-time, automated and adaptive to changes in the organisation and its environment". Many information technology architectures today are built to support adaptive changes (e.g. Service Oriented Architectures (SOA) and so-called Platform-as-a- |
https://en.wikipedia.org/wiki/Unbound%20%28DNS%20server%29 | Unbound is a validating, recursive, and caching DNS resolver product from NLnet Labs. It is distributed free of charge in open-source form under the BSD license.
Features
Caching resolver with prefetching of popular items before they expire
DNS over TLS forwarding and server, with domain-validation
DNS over HTTPS
Query Name Minimization
Aggressive Use of DNSSEC-Validated Cache
Authority zones, for a local copy of the root zone
DNS64
DNSCrypt
DNSSEC validating
EDNS Client Subnet
History
Originally designed by Jakob Schlyter of Kirei and Roy Arends of Nominet in 2004, funding was provided by VeriSign and ep.net to develop a prototype written in Java (David Blacka and Matt Larson, VeriSign). In 2006, the prototype was re-written for high-performance in the C programming language by NLnet Labs.
Unbound is designed as a set of modular components that incorporate modern features, such as enhanced security (DNSSEC) validation, Internet Protocol Version 6 (IPv6), and a client resolver application programming interface library as an integral part of the architecture. Originally written for POSIX-compatible Unix-like operating system, it runs on FreeBSD, OpenBSD, NetBSD, macOS, and Linux, as well as Microsoft Windows.
Reception
Unbound has supplanted the Berkeley Internet Name Daemon (BIND) as the default, base-system name server in FreeBSD and OpenBSD, where it is perceived as smaller, more modern, and more secure for most applications.
See also
NSD, an authoritative name server, also from NLnet Labs
Comparison of DNS server software |
https://en.wikipedia.org/wiki/Cryptoteuthis | Cryptoteuthis brevibracchiata, the short-arm flapjack octopod, is a deepwater species of octopod. It is the only species in the monotypic genus Cryptoteuthis one of the cirrate octopuses of the family Grimpoteuthidae, the umbrella octopuses. It is known from a single specimen which was collected in the northeastern Atlantic Ocean. It has characteristics which are shared with two other genera, Opisthoteuthis and Grimpoteuthis, but is sufficiently distinctive from either of these to warrant the erection of a new genus.
Description
Cryptoteuthis brevibracchiata is a bell-shaped octopus with a semi-gelatinous, semi-transparent body, except for the dark tips of the oral web and the tips of the fins. The fins are small and round, and their length is equal to half the width of the head. It has short arms, each with a single row of small, broad suckers and with a double row of cirri which are of moderate length, with each cirrus just longer than the diameter of the suckers. The longest arm has 48 suckers and the web is around half the length of the arms. The eyes are laterally positioned and the optic nerve passes through the white body in a single bundle. There are no posterior salivary glands, radula or ink sac. The digestive gland is entire. It has a simple U-shaped shell. The gills have 7 primary lamellae. The mantle length 35 mm and the total length is 121mm.
Distribution and habitat
Cryptoteuthis brevibracchiata was described from a single specimen, an immature female, collected in the northeastern Atlantic Ocean near the Porcupine Seabight at 49°54 N, 12°21 W from a depth of between 2,274 and 2,300m, south west of Ireland. The habitat is unknown but this species is unlikely to be demersal and it shows adaptations which suggest that it may be a benthic species which a preference for soft substrates, like some related taxa, such as Grimpoteuthis. |
https://en.wikipedia.org/wiki/Cotoneaster%20%C3%97%20watereri | Cotoneaster × watereri, or Waterer's cotoneaster, is a large evergreen shrub belonging to the genus Cotoneaster.
It is an artificial hybrid, initially of Cotoneaster frigidus, Cotoneaster henrianus and Cotoneaster salicifolius. Later also Cotoneaster rugosus and Cotoneaster sargentii were probably involved.
Description
Cotoneaster × watereri is about 4 m tall, up to 8 m at maturity. Leaves are elliptical, dark green, up to 12 cm long and 3 cm wide. This plant shows large attractive inflorescences with white small flowers and large spherical coral red berries of about 6–9 mm. It is in flower from June to July. |
https://en.wikipedia.org/wiki/Plant%20community | A plant community is a collection or association of plant species within a designated geographical unit, which forms a relatively uniform patch, distinguishable from neighboring patches of different vegetation types. The components of each plant community are influenced by soil type, topography, climate and human disturbance. In many cases there are several soil types present within a given plant community. This is because the soil type within an area is influenced by two factors, the rate at which water infiltrates or exits (via evapotranspiration) the soil, as well as the rate at which organic matter (any carbon-based compound within the environment, such as decaying plant matter) enters or decays from the soil. Plant communities are studied substantially by ecologists, due to providing information on the effects of dispersal, tolerance to environmental conditions, and response to disturbance of a variety of plant species, information valuable to the comprehension of various plant community dynamics.
Definition
A plant community can be described floristically (the species of flowers or flora the plant community contains) and/or phytophysiognomically (the physical structure or appearance of the plant community). For example, a forest (a community of trees) includes the overstory, or upper tree layer of the canopy, as well as the understory, a layer consisting of trees and shrubs located beneath the canopy but above the forest floor. The understory can be further subdivided into the shrub layer, composed of vegetation and trees between a height of approximately one to five meters, the herbaceous layer, composed of vascular plants at a height of one meter or less, and sometimes also the moss layer, a layer of non-vascular bryophytes typically present at ground level (approximately 0.15 meters in height or less). In some cases of complex forests there is also a well-defined lower tree layer. A plant community is similar in concept to a vegetation type, with the forme |
https://en.wikipedia.org/wiki/Diode%20matrix | A diode matrix is a two-dimensional grid of wires: each "intersection" wherein one-row crosses over another has either a diode connecting them, or the wires are isolated from each other.
It is one of the popular techniques for implementing a read-only memory. A diode matrix is used as the control store or microprogram in many early computers. A logically equivalent transistor matrix is still used as the control store or microprogram or 'decode ROM' in many modern microprocessors.
A single row of the diode matrix (or transistor matrix) is activated at any one instant.
Charge flows through each diode connected to that row. That activates the column corresponding to each row. The only activated control signals during that instant were those whose corresponding column wire was connected with a diode to that row.
History
A diode matrix ROM was used in many computers in the 1960s and 70s, as well as electronic desk calculators and keyboard matrix circuits for computer terminals. A keyboard matrix circuit has a very similar grid of diodes, but is used differently.
The microsequencer of many early computers, perhaps starting with the Whirlwind I, simply activated each row of the diode matrix in sequence, and after the last row was activated, started over again with the first row.
The technique of microprogramming as first described by Maurice Wilkes in terms of a second diode matrix added to a diode matrix control store. Later computers used a variety of alternative implementations of the control store, but eventually returned to a diode matrix or transistor matrix. A person would microprogram the control store on such early computers by manually attaching diodes to selected intersections of the word lines and bit lines. In schematic diagrams, the word lines are usually horizontal, and the bit lines are usually vertical.
The control store on some minicomputers was one or more programmable logic array chips. The "blank" PLA from the chip manufacturer came with a diode |
https://en.wikipedia.org/wiki/Compressed%20file%20library |
A compressed file library (CFL) is designed to work as a virtual file system for programs, especially for video games. By compressing various game resources into one file, it is able to lower the number of file accesses. The resources can also be encrypted in the CFL.
CFL is used by X-Forge, the multi-platform wireless 3D game engine developed by Fathammer Ltd. It is also used by IMVU for its 3D character models and accessories.
See also
Doom WAD, a similar file system |
https://en.wikipedia.org/wiki/Film%20industry%20and%20video%20game%20industry | The film industry and video game industry have a long and detailed common history – the two industries have collaborated many times since the 1980s. This includes collaboration between people from both industries and projects resulting in products such as video games, film adaptations of video games, among other things.
History
1980s
Video games have also been adapted into films, beginning in the early 1980s. Films closely related to the video game industries were done in this time, such as Tron and Cloak & Dagger, but only after the release of several films based on well-known brands has this genre become recognized in its own right. Video game films can take several forms, such as traditionally animated films based on the Pokémon, or computer-animated such as Final Fantasy: The Spirits Within. There exist Original Video Animations (OVAs) based on popular games such as Dead Space: Downfall, Halo Legends, Dante's Inferno: An Animated Epic which may be released direct-to-video.
1990s
The 10th Planet which was scheduled to be released in October 1997 was canceled. The game was a collaboration between Bethesda Softworks and Centropolis Entertainment (film production company founded by Roland Emmerich and Dean Devlin). Christopher Weaver, the founder of Bethesda was introduced to Devlin and Emmerich through mutual friends.
In 1993, Super Mario Bros. was released, a film loosely based on the Mario video game series by Nintendo. The film was poorly received by critics.
Steven Spielberg proposed the concept for the first Medal of Honor video game in the spring of 1997.
2000s
In 2000, Lionsgate CEO and Vice Chairman at the time Jon Feltheimer as well as Dean Devlin joined ZeniMax Media as company advisors. Also that year, Sam Simon joined ZeniMax as President of e-Nexus Studios.
In 2002, Vin Diesel formed his own development studio, Tigon Studios.
In October 2005, Steven Spielberg and Electronic Arts partnered to develop 3 video games.
In December 2007, Jerry B |
https://en.wikipedia.org/wiki/Society%20of%20Mind | The Society of Mind is both the title of a 1986 book and the name of a theory of natural intelligence as written and developed by Marvin Minsky.
In his book of the same name, Minsky constructs a model of human intelligence step by step, built up from the interactions of simple parts called agents, which are themselves mindless. He describes the postulated interactions as constituting a "society of mind", hence the title.
The book
The work, which first appeared in 1986, was the first comprehensive description of Minsky's "society of mind" theory, which he began developing in the early 1970s. It is composed of 270 self-contained essays which are divided into 30 general chapters. The book was also made into a CD-ROM version.
In the process of explaining the society of mind, Minsky introduces a wide range of ideas and concepts. He develops theories about how processes such as language, memory, and learning work, and also covers concepts such as consciousness, the sense of self, and free will; because of this, many view The Society of Mind as a work of philosophy.
The book was not written to prove anything specific about AI or cognitive science, and does not reference physical brain structures. Instead, it is a collection of ideas about how the mind and thinking work on the conceptual level.
The theory
Minsky first started developing the theory with Seymour Papert in the early 1970s. Minsky said that the biggest source of ideas about the theory came from his work in trying to create a machine that uses a robotic arm, a video camera, and a computer to build with children's blocks.
Nature of mind
A core tenet of Minsky's philosophy is that "minds are what brains do". The society of mind theory views the human mind and any other naturally evolved cognitive systems as a vast society of individually simple processes known as agents. These processes are the fundamental thinking entities from which minds are built, and together produce the many abilities we attribute |
https://en.wikipedia.org/wiki/Sequence%20learning | In cognitive psychology, sequence learning is inherent to human ability because it is an integrated part of conscious and nonconscious learning as well as activities. Sequences of information or sequences of actions are used in various everyday tasks: "from sequencing sounds in speech, to sequencing movements in typing or playing instruments, to sequencing actions in driving an automobile." Sequence learning can be used to study skill acquisition and in studies of various groups ranging from neuropsychological patients to infants. According to Ritter and Nerb, “The order in which material is presented can strongly influence what is learned, how fast performance increases, and sometimes even whether the material is learned at all.” Sequence learning, more known and understood as a form of explicit learning, is now also being studied as a form of implicit learning as well as other forms of learning. Sequence learning can also be referred to as sequential behavior, behavior sequencing, and serial order in behavior.
History
In the first half of the 20th century, Margaret Floy Washburn, John B. Watson, and other behaviorists believed behavioral sequencing to be governed by the reflex chain, which states that stimulation caused by an initial movement triggers an additional movement, which triggers another additional movement, and so on. In 1951, Karl Lashley, a neurophysiologist at Harvard University, published “The Problem of Serial Order in Behavior,” addressing the current beliefs about sequence learning and introducing his hypothesis. He criticized the previous view on the basis of six lines of evidence:
The first line is that movements can occur even when sensory feedback is interrupted. The second is that some movement sequences occur too quickly for elements of the sequences to be triggered by feedback from the preceding elements. Next is that the errors in behavior suggest internal plans for what will be done later. Also, the time to initiate a movement sequence |
https://en.wikipedia.org/wiki/Essential%20range | In mathematics, particularly measure theory, the essential range, or the set of essential values, of a function is intuitively the 'non-negligible' range of the function: It does not change between two functions that are equal almost everywhere. One way of thinking of the essential range of a function is the set on which the range of the function is 'concentrated'.
Formal definition
Let be a measure space, and let be a topological space. For any -measurable , we say the essential range of to mean the set
Equivalently, , where is the pushforward measure onto of under and denotes the support of
Essential values
We sometimes use the phrase "essential value of " to mean an element of the essential range of
Special cases of common interest
Y = C
Say is equipped with its usual topology. Then the essential range of f is given by
In other words: The essential range of a complex-valued function is the set of all complex numbers z such that the inverse image of each ε-neighbourhood of z under f has positive measure.
(Y,T) is discrete
Say is discrete, i.e., is the power set of i.e., the discrete topology on Then the essential range of f is the set of values y in Y with strictly positive -measure:
Properties
The essential range of a measurable function, being the support of a measure, is always closed.
The essential range ess.im(f) of a measurable function is always a subset of .
The essential image cannot be used to distinguish functions that are almost everywhere equal: If holds -almost everywhere, then .
These two facts characterise the essential image: It is the biggest set contained in the closures of for all g that are a.e. equal to f:
.
The essential range satisfies .
This fact characterises the essential image: It is the smallest closed subset of with this property.
The essential supremum of a real valued function equals the supremum of its essential image and the essential infimum equals the infimum of its essential range. Consequently, |
https://en.wikipedia.org/wiki/Server%20Message%20Block | Server Message Block (SMB) is a communication protocol mainly used by Microsoft Windows equipped computers normally used to share files, printers, serial ports, and miscellaneous communications between nodes on a network. SMB implementation consists of two vaguely named Windows services: "Server" (ID: LanmanServer) and "Workstation" (ID: LanmanWorkstation). It uses NTLM or Kerberos protocols for user authentication. It also provides an authenticated inter-process communication (IPC) mechanism.
SMB was originally developed in 1983 by Barry A. Feigenbaum at IBM and intended to provide shared access to files and printers across nodes on a network of systems running IBM's OS/2. In 1987, Microsoft and 3Com implemented SMB in LAN Manager for OS/2, at which time SMB used the NetBIOS service atop the NetBIOS Frames protocol as its underlying transport. Later, Microsoft implemented SMB in Windows NT 3.1 and has been updating it ever since, adapting it to work with newer underlying transports: TCP/IP and NetBT. SMB over QUIC was introduced in Windows Server 2022.
In 1996, Microsoft published a version of SMB 1.0 with minor modifications under the Common Internet File System (CIFS ) moniker. CIFS was compatible with even the earliest incarnation of SMB, including LAN Manager's. It supports symbolic links, hard links, and larger file size, but none of the features of SMB 2.0 and later. Microsoft's proposal, however, remained an Internet Draft and never achieved standard status. Microsoft has since discontinued use of the CIFS moniker but continues developing SMB and making subsequent specifications publicly available. Samba is a free software reimplementation of the SMB protocol and the Microsoft extensions to it.
Features
Server Message Block (SMB) enables file sharing, printer sharing, network browsing, and inter-process communication (through named pipes) over a computer network. SMB serves as the basis for Microsoft's Distributed File System implementation.
SMB relies |
https://en.wikipedia.org/wiki/Combinatorial%20species | In combinatorial mathematics, the theory of combinatorial species is an abstract, systematic method for deriving the generating functions of discrete structures, which allows one to not merely count these structures but give bijective proofs involving them. Examples of combinatorial species are (finite) graphs, permutations, trees, and so on; each of these has an associated generating function which counts how many structures there are of a certain size. One goal of species theory is to be able to analyse complicated structures by describing them in terms of transformations and combinations of simpler structures. These operations correspond to equivalent manipulations of generating functions, so producing such functions for complicated structures is much easier than with other methods. The theory was introduced, carefully elaborated and applied by Canadian researchers around André Joyal.
The power of the theory comes from its level of abstraction. The "description format" of a structure (such as adjacency list versus adjacency matrix for graphs) is irrelevant, because species are purely algebraic. Category theory provides a useful language for the concepts that arise here, but it is not necessary to understand categories before being able to work with species.
The category of species is equivalent to the category of symmetric sequences in finite sets.
Definition of species
Any species consists of individual combinatorial structures built on the elements of some finite set: for example, a combinatorial graph is a structure of edges among a given set of vertices, and the species of graphs includes all graphs on all finite sets. Furthermore, a member of a species can have its underying set relabeled by the elements of any other equinumerous set, for example relabeling the vertices of a graph gives "the same graph structure" on the new vertices, i.e. an isomorphic graph.
This leads to the formal definition of a combinatorial species. Let be the category of finite |
https://en.wikipedia.org/wiki/Conformal%20loop%20ensemble | A conformal loop ensemble (CLEκ) is a random collection of non-crossing loops in a simply connected, open subset of the plane. These random collections of loops are indexed by a parameter κ, which may be any real number between 8/3 and 8. CLEκ is a loop version of the Schramm-Loewner evolution: SLEκ is designed to model a single discrete random interface, while CLEκ models a full collection of interfaces.
In many instances for which there is a conjectured or proved relationship between a discrete model and SLEκ, there is also a conjectured or proved relationship with CLEκ. For example:
CLE3 is the limit of interfaces for the critical Ising model.
CLE4 may be viewed as the 0-set of the Gaussian free field.
CLE16/3 is a scaling limit of cluster interfaces in critical FK Ising percolation.
CLE6 is a scaling limit of critical percolation on the triangular lattice.
Constructions
For 8/3 < κ < 8, CLEκ may be constructed using a branching variation of an SLEκ process. When 8/3 < κ ≤ 4, CLEκ may be alternatively constructed as the collection of outer boundaries of Brownian loop soup clusters.
Properties
CLEκ is conformally invariant, which means that if is a conformal map, then the law of a CLE in D''' is the same as the law of the image of all the CLE loops in D under the map .
Since CLEκ may be defined using an SLEκ process, CLE loops inherit many path properties from SLE. For example, each CLEκ loop is a fractal with almost-sure Hausdorff dimension 1+κ/8. Each loop is almost surely simple (no self intersections) when 8/3 < κ ≤ 4 and almost surely self-touching when 4 < κ < 8.
The set of all points not surrounded by any loop, which is called the gasket, has Hausdorff dimension 1 + 2/κ + 3κ/32 almost surely (Random soups, carpets and fractal dimensions by Nacu and Werner. Since this dimension is strictly greater than 1+κ/8, there are almost surely points not contained in or surrounded by any loop. However, since the gasket dimension is strictly less than 2, almos |
https://en.wikipedia.org/wiki/Anton%20Kotzig | Anton Kotzig (22 October 1919 – 20 April 1991) was a Slovak–Canadian mathematician, expert in statistics, combinatorics and graph theory.
The Ringel–Kotzig conjecture on graceful labeling of trees is named after him and Gerhard Ringel.
Kotzig's theorem on the degrees of vertices in convex polyhedra is also named after him.
Biography
Kotzig was born in Kočovce, a village in Western Slovakia, in 1919. He studied at the secondary grammar school in Nové Mesto nad Váhom, and began his undergraduate studies at Charles University in Prague. After the closure of Czech universities in 1939, he moved to Bratislava, where in 1943 he earned a doctoral degree (RNDr.) in mathematical statistics from Comenius University in Bratislava. He remained in Bratislava working at the Central Bureau of Social Insurance for Slovakia, as the head of department of mathematical statistics.
Later he published a book on economy planning. From 1951 to 1959, he lectured at Vysoká škola Ekonomická (today University of Economics in Bratislava), where he served as rector from 1952 to 1958. Thus he spent 20 years in close contact with applications of mathematics.
In 1959, he left the University of Economics to become the head of the newly created Mathematical Institute of the Slovak Academy of Sciences, where he remained until 1964. From 1965 to 1969, he was head of the department of Applied Mathematics on Faculty of Natural Sciences of Comenius University, where he was also dean for one year. He also earned a habilitation degree (DrSc.) from Charles University in 1961 for a thesis in graph theory (relation and regular relation of finite graphs).
Kotzig established the now well-known Slovak School of Graph Theory. One of his first students was Juraj Bosák, who was awarded the Czechoslovak State Prize in 1969.
In 1969, Kotzig moved to Canada, and spent a year at the University of Calgary. He became a researcher at the Centre de recherches mathematiques (CRM) and the University of Montreal in 1970, |
https://en.wikipedia.org/wiki/Halperin%20conjecture | In rational homotopy theory, the Halperin conjecture concerns the Serre spectral sequence of certain fibrations. It is named after the Canadian mathematician Stephen Halperin.
Statement
Suppose that is a fibration of simply connected spaces such that is rationally elliptic and (i.e., has non-zero Euler characteristic), then the Serre spectral sequence associated to the fibration collapses at the page.
Status
As of 2019, Halperin's conjecture is still open. Gregory Lupton has reformulated the conjecture in terms of formality relations.
Notes |
https://en.wikipedia.org/wiki/Zinc%20transporter%208 | Zinc transporter 8 (ZNT8) is a protein that in humans is encoded by the SLC30A8 gene. ZNT8 is a zinc transporter related to insulin secretion in humans. In particular, ZNT8 is critical for the accumulation of zinc into beta cell secretory granules and the maintenance of stored insulin as tightly packaged hexamers. Certain alleles of the SLC30A8 gene may increase the risk for developing type 2 diabetes, but a loss-of-function mutation appears to greatly reduce the risk of diabetes.
Clinical significance
Association with type 2 diabetes (T2D)
Twelve rare variants in SLC30A8 have been identified through the sequencing or genotyping of approximately 150,000 individuals from 5 different ancestry groups. SLC30A8 contains a common variant (p.Trp325Arg), which is associated with T2D risk and levels of glucose and proinsulin. Individuals carrying protein-truncating variants collectively had 65% reduced risk of T2D. Additionally, non-diabetic individuals from Iceland harboring a frameshift variant p. Lys34Serfs*50 demonstrated reduced glucose levels. Earlier functional studies of SLC30A8 suggested that reduced zinc transport increased T2D risk. Conversely, loss-of-function mutations in humans indicate that SLC30A8 haploinsufficiency protects against T2D. Therefore, ZnT8 inhibition can serve as a therapeutic strategy in preventing T2D.
See also
Solute carrier family |
https://en.wikipedia.org/wiki/Muhammad%20Hazi | Muhammad Hazi (Arabic: محمد حازي) is an Algerian writer. He graduated from École Normale Supérieure, University Of Science And Technology Houari Boumediene, and Universities of Paris VI and XI (Center of Orsay). He is an associate professor at the National School of Public Works of Kouba, the Polytechnic School of El Harrach, and the Ecole Normale Supérieure of Laghouat. He also worked at the Community College of Rafha in Saudi Arabia. He was a former director of studies and training at École Normale Supérieure in El-Kobba. He was also previously the head of the mathematics department at the same school and still works there as a teacher.
Career
Apart from this academic career, Hazi has excelled in the field of writing, as he has published more than ten books in various fields mostly centered on science. His book “Key Principles in Topological Concepts” was widely popular and got adopted by educational institutions in Algeria. It is the first book in a trilogy including 'Key Principles in Topological Concepts,' 'Comprehensive Lessons in Metric Spaces,' and 'The Abstract Seat of Semantic Analysis.' Hazi’s second book in the series, “Adequate Lessons in Metric Spaces,” a book in which he reviewed, in the context of metric spaces, the concepts of convergence, continuity, agglutination, and interconnectedness, as well as several famous and important theorems, which are among the main pillars of semantic analysis.
His third book titled “Functional analysis bench; Solved Exercises and Practice” is the final in the series. In this book, Hazi focuses on a structural tool, the systematic spaces and their features, and reviews aspects of its applications and ramifications. It was issued in six chapters: Systematic space: definitions and general properties, The space of linear and radial applications, additive families, Hilbertarian spaces, Fourier series, and an introduction to the theory of influences. Each chapter also contains many solved problems and exercises, and oth |
https://en.wikipedia.org/wiki/Effusion | In physics and chemistry, effusion is the process in which a gas escapes from a container through a hole of diameter considerably smaller than the mean free path of the molecules. Such a hole is often described as a pinhole and the escape of the gas is due to the pressure difference between the container and the exterior. Under these conditions, essentially all molecules which arrive at the hole continue and pass through the hole, since collisions between molecules in the region of the hole are negligible. Conversely, when the diameter is larger than the mean free path of the gas, flow obeys the Sampson flow law.
In medical terminology, an effusion refers to accumulation of fluid in an anatomic space, usually without loculation. Specific examples include subdural, mastoid, pericardial and pleural effusions.
Etymology
The word effusion derives from the Latin word, effundo, which means "shed, pour forth, pour out, utter, lavish, waste."
Effusion into vacuum
Effusion from an equilibrated container into outside vacuum can be calculated based on kinetic theory. The number of atomic or molecular collisions with a wall of a container per unit area per unit time (impingement rate) is given by:
assuming mean free path is much greater than pinhole diameter and the gas can be treated as an ideal gas.
If a small area on the container is punched to become a small hole, the effusive flow rate will be
where is the molar mass, is the Avogadro constant, and is the gas constant.
The average velocity of effused particles is
Combined with the effusive flow rate, the recoil/thrust force on the system itself is
An example is the recoil force on a balloon with a small hole flying in vacuum.
Measures of flow rate
According to the kinetic theory of gases, the kinetic energy for a gas at a temperature is
where is the mass of one molecule, is the root-mean-square speed of the molecules, and is the Boltzmann constant. The average molecular speed can be calculated from the Ma |
https://en.wikipedia.org/wiki/Gas%20in%20a%20box | In quantum mechanics, the results of the quantum particle in a box can be used to look at the equilibrium situation for a quantum ideal gas in a box which is a box containing a large number of molecules which do not interact with each other except for instantaneous thermalizing collisions. This simple model can be used to describe the classical ideal gas as well as the various quantum ideal gases such as the ideal massive Fermi gas, the ideal massive Bose gas as well as black body radiation (photon gas) which may be treated as a massless Bose gas, in which thermalization is usually assumed to be facilitated by the interaction of the photons with an equilibrated mass.
Using the results from either Maxwell–Boltzmann statistics, Bose–Einstein statistics or Fermi–Dirac statistics, and considering the limit of a very large box, the Thomas–Fermi approximation (named after Enrico Fermi and Llewellyn Thomas) is used to express the degeneracy of the energy states as a differential, and summations over states as integrals. This enables thermodynamic properties of the gas to be calculated with the use of the partition function or the grand partition function. These results will be applied to both massive and massless particles. More complete calculations will be left to separate articles, but some simple examples will be given in this article.
Thomas–Fermi approximation for the degeneracy of states
For both massive and massless particles in a box, the states of a particle are
enumerated by a set of quantum numbers . The magnitude of the momentum is given by
where h is Planck's constant and L is the length of a side of the box. Each possible state of a particle can be thought of as a point on a 3-dimensional grid of positive integers. The distance from the origin to any point will be
Suppose each set of quantum numbers specify f states where f is the number of internal degrees of freedom of the particle that can be altered by collision. For example, a spin particle would |
https://en.wikipedia.org/wiki/Whitney%27s%20planarity%20criterion | In mathematics, Whitney's planarity criterion is a matroid-theoretic characterization of planar graphs, named after Hassler Whitney. It states that a graph G is planar if and only if its graphic matroid is also cographic (that is, it is the dual matroid of another graphic matroid).
In purely graph-theoretic terms, this criterion can be stated as follows: There must be another (dual) graph G'=(V',E') and a bijective correspondence between the edges E' and the edges E of the original graph G, such that a subset T of E forms a spanning tree of G if and only if the edges corresponding to the complementary subset E-T form a spanning tree of G'.
Algebraic duals
An equivalent form of Whitney's criterion is that a graph G is planar if and only if it has a dual graph whose graphic matroid is dual to the graphic matroid of G.
A graph whose graphic matroid is dual to the graphic matroid of G is known as an algebraic dual of G. Thus, Whitney's planarity criterion can be expressed succinctly as: a graph is planar if and only if it has an algebraic dual.
Topological duals
If a graph is embedded into a topological surface such as the plane, in such a way that every face of the embedding is a topological disk, then the dual graph of the embedding is defined as the graph (or in some cases multigraph) H that has a vertex for every face of the embedding, and an edge for every adjacency between a pair of faces.
According to Whitney's criterion, the following conditions are equivalent:
The surface on which the embedding exists is topologically equivalent to the plane, sphere, or punctured plane
H is an algebraic dual of G
Every simple cycle in G corresponds to a minimal cut in H, and vice versa
Every simple cycle in H corresponds to a minimal cut in G, and vice versa
Every spanning tree in G corresponds to the complement of a spanning tree in H, and vice versa.
It is possible to define dual graphs of graphs embedded on nonplanar surfaces such as the torus, but these duals do not ge |
https://en.wikipedia.org/wiki/Quantcast%20File%20System | Quantcast File System (QFS) is an open-source distributed file system software package for large-scale MapReduce or other batch-processing workloads. It was designed as an alternative to the Apache Hadoop Distributed File System (HDFS), intended to deliver better performance and cost-efficiency for large-scale processing clusters.
Design
QFS is software that runs on a cluster of hundreds or thousands of commodity Linux servers and allows other software layers to interact with them as if they were one giant hard drive. It has three components:
A chunk server runs on each machine that will host data, manages I/O to its hard drives, and monitors its activity and capacity.
A central process called the metaserver keeps the directory structure and maps of files to physical storage. It coordinates activities of all the chunk servers and monitors the overall health of the file system. For high performance it holds all its data in memory, writing checkpoints and transaction logs to disk for recovery.
A client component is the interface point that presents a file system application programming interface (API) to other layers of the software. It makes requests of the metaserver to identify which chunk servers hold (or will hold) its data, then interacts with the chunk servers directly to read and write.
In a cluster of hundreds or thousands of machines, the odds are low that all will be running and reachable at any given moment, so fault tolerance is the central design challenge. QFS meets it with Reed–Solomon error correction. The form of Reed–Solomon encoding used in QFS stores redundant data in nine places and can reconstruct the file from any six of these stripes. When it writes a file, it by default stripes it across nine physically different machines — six holding the data, three holding parity information. Any three of those can become unavailable. If any six remain readable, QFS can reconstruct the original data. The result is fault tolerance at a cost of a 50% expa |
https://en.wikipedia.org/wiki/Network%20virtualization | In computing, network virtualization is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization.
Network virtualization is categorized as either external virtualization, combining many networks or parts of networks into a virtual unit, or internal virtualization, providing network-like functionality to software containers on a single network server.
In software testing, software developers use network virtualization to test software which are under development in a simulation of the network environments in which the software is intended to operate. As a component of application performance engineering, network virtualization enables developers to emulate connections between applications, services, dependencies, and end users in a test environment without having to physically test the software on all possible hardware or system software. The validity of the test depends on the accuracy of the network virtualization in emulating real hardware and operating systems.
Components
Various equipment and software vendors offer network virtualization by combining any of the following:
Network hardware, such as switches and network adapters, also known as network interface cards (NICs)
Network elements, such as firewalls and load balancers
Networks, such as virtual LANs (VLANs) and containers such as virtual machines (VMs)
Network storage devices
Network machine-to-machine elements, such as telecommunications devices
Network mobile elements, such as laptop computers, tablet computers, and smartphones
Network media, such as Ethernet and Fibre Channel
External virtualization
External network virtualization combines or subdivides one or more local area networks (LANs) into virtual networks to improve a large network's or data center's efficiency. A virtual lo |
https://en.wikipedia.org/wiki/Frontoparietal%20network | The frontoparietal network (FPN), generally also known as the central executive network (CEN) or, more specifically, the lateral frontoparietal network (L-FPN) (see Nomenclature), is a large-scale brain network primarily composed of the dorsolateral prefrontal cortex and posterior parietal cortex, around the intraparietal sulcus. It is involved in sustained attention, complex problem-solving and working memory.
The FPN is one of three networks in the so-called triple-network model, along with the salience network and the default mode network (DMN). The salience network facilitates switching between the FPN and DMN.
Anatomy
The FPN is primarily composed of the rostral lateral and dorsolateral prefrontal cortex (especially the middle frontal gyrus) and the anterior inferior parietal lobule. Additional regions include the middle cingulate gyrus and potentially the dorsal precuneus, posterior inferior temporal lobe, dorsomedial thalamus and the head of the caudate nucleus.
Function
The FPN is involved in executive function and goal-oriented, cognitively demanding tasks. It is crucial for rule-based problem solving, actively maintaining and manipulating information in working memory and making decisions in the context of goal-directed behaviour. Based on current cognitive demands, the FPN flexibly divides into two subsystems that connect to other networks: the default mode network for introspective processes and the dorsal attention network for perceptual attention.
Clinical significance
Disruption of the nodes of the FPN has been found in virtually every psychiatric and neurological disorder, from autism, schizophrenia and depression to frontotemporal dementia and Alzheimer's disease.
Nomenclature
The term central executive network (CEN) is generally equivalent to the frontoparietal network in literature, distinguishing it from the dorsal attention network (DAN), with which it has several similarities, though sometimes it has been used to include the DAN.
The |
https://en.wikipedia.org/wiki/Power%20shuttle | A power shuttle is an additional unit used in transmissions and is generally used in agricultural tractors. While the vehicle is moving forwards, the driver can pull a lever that makes it stop and go backwards at the same speed. Power Shuttles are also known under various trade names including Power Reverser
In forward/reverse position of the F-R lever, the pressure is built in the system due to flow to wet clutch. During, the pressure rise,F-R clutch is in energized condition which makes the vehicle to move forward/Reverse direction. Flow to tank line is blocked during the flow to F/R clutch.
Power shuttle are incorporated in transmissions in three forms: counter-shaft, full planetary (power shifts), and CVT transmissions.
Counter shaft transmissions
In this case generally forward reverse synchronizers are replaced by the multi-plate friction clutches. Typically the multi-plate clutches are arranged on the main shaft or on the counter shaft. The forward reverse section of the gear box is generally located in the forward section as close to the engine as possible. This is beneficial to the forward reverse control elements as they are not subjected to the high relative torque. The challenge involved in providing this feature in the existing transmissions is the complex shaft arrangement. This problem arises due to the limitation of centre distance between the two shafts and fixed axial dimensions due to the vehicle size limitations.
Full planetary (power shift)
In this type of transmissions the planetary action is used for providing reverse or forward action to the gear box.
CVT/IVT
Here the automatic nature of the gear box takes care of the direction change by either engaging planetary sets or by engaging multi-plate clutches or by some other means.
Features of power shuttle transmissions.
Power shuttle transmissions were invented for mining and earth moving applications. The needs in the areas were:
Quick shuttle response
Left hand shuttle lever (so that rig |
https://en.wikipedia.org/wiki/Veritas%20Cluster%20Server | Veritas Cluster Server (rebranded as Veritas Infoscale Availability and also known as VCS and also sold bundled in the SFHA product) is a high-availability cluster software for Unix, Linux and Microsoft Windows computer systems, created by Veritas Technologies. It provides application cluster capabilities to systems running other applications, including databases, network file sharing, and electronic commerce websites.
Description
High-availability clusters (HAC) improve application availability by failing or switching them over in a group of systems—as opposed to high-performance clusters, which improve application performance by running them on multiple systems simultaneously.
Most Veritas Cluster Server implementations attempt to build availability into a cluster, eliminating single points of failure by making use of redundant components like multiple network cards, storage area networks in addition to the use of VCS.
Similar products include Fujitsu PRIMECLUSTER, IBM PowerHA System Mirror, HP ServiceGuard, IBM Tivoli System Automation for Multiplatforms (SA MP), Linux-HA, OpenSAF, Microsoft Cluster Server (MSCS), NEC ExpressCluster, Red Hat Cluster Suite, SteelEye LifeKeeper and Sun Cluster. VCS is one of the few products in the industry that provides both high availability and disaster recovery across all major operating systems while supporting 40+ major application/replication technologies out of the box.
VCS is mostly a user-level clustering software; most of its processes are normal system processes on the systems it operates on, and have no special access to the operating system or kernel functions in the host systems. However, the interconnect (heartbeat) technology used with VCS is a proprietary Layer 2 ethernet-based protocol that is run in the kernel space using kernel modules. The group membership protocol that runs on top of the interconnect heartbeat protocol is also implemented in the kernel. In case of a split brain, the 'fencing' module doe |
https://en.wikipedia.org/wiki/Spontelectrics | Spontelectrics is a form of solid state thin films with some peculiar physical properties.
Properties
When laid down as thin films tens to hundreds of molecular layers thick, a range of materials spontaneously generate large electric fields. The electric fields can be greater than 108 V/m.
Spontelectric behaviour is intrinsic to the dipolar nature of the constituent molecules.
The detection (in ~2009) of spontaneous electric fields in numerous solid films prepared by vapour deposition raises fundamental questions about the nature of disordered materials.
David Field played a major role in the discovery of spontelectrics.
External links
Spontelectrics, or the solid state continues to surprise us
Fysikoverraskelse: Elektrisk spænding opstår spontant i tyndfilm af lattergas
Another way to sponteletrics. |
https://en.wikipedia.org/wiki/Vogue%20Scandinavia | Vogue Scandinavia is the Scandinavian edition of the American fashion and lifestyle monthly magazine Vogue. The magazine has been published since August 2021 and is the twenty-sixth local edition of Vogue.
History
In June 2020, Vogue launched a Scandinavian edition of the magazine, with Martina Bonnier being the Editor-in-Chief, featuring Scandinavian fashion as well covering politics of the Nordic region. It was announced that the magazine would be published in English, so it would be accessible worldwide. It was also revealed that in effort to be more sustainable, the magazine would be the first edition of Vogue not to be sold in physical shops. In May 2021, Vogue Scandinavia opened a digital flagship store.
The first issue was released on August 2021, with Greta Thunberg, a Swedish environmental activist, on its cover. In February 2022, Prince Nikolai of Denmark appeared on the fourth issue of the magazine.
See also
List of Vogue Scandinavia cover models |
https://en.wikipedia.org/wiki/Geiriadur%20Prifysgol%20Cymru | Geiriadur Prifysgol Cymru (GPC) (The University of Wales Dictionary) is the only standard historical dictionary of the Welsh language, aspiring to be "comparable in method and scope to the Oxford English Dictionary". Vocabulary is defined in Welsh, and English equivalents are given. Detailed attention is given to variant forms, collocations, and etymology.
The first edition was published in four volumes between 1967 and 2002, containing 7.3 million words of text in 3,949 pages, documenting 106,000 headwords. There are almost 350,000 dated citations dating from the year 631 up to 2000, with 323,000 Welsh definitions and 290,000 English equivalents, of which 85,000 have included etymologies.
History
In 1921, a small team at the National Library of Wales, Aberystwyth, organised by the Rev. J. Bodvan Anwyl, arranged for volunteer readers to record words. The task of editing the dictionary was undertaken by R. J. Thomas in the 1948/49 academic year.
The first edition of Volume I appeared in 1967, followed by Volume II in 1987, Volume III in 1998, and Volume IV, edited by Gareth A. Bevan and P. J. Donovan, in December 2002. Work then immediately began on a second edition.
Following the retirement of the previous editors Gareth A. Bevan and Patrick J. Donovan, Andrew Hawke was appointed as managing editor in January 2008.
The second edition is based not only on the Dictionary's own collection of citation slips, but also on a wide range of electronic resources such as the Welsh Prose 1300-1425 website (Cardiff University), JISC Historic Books including EEBO and EECO (The British Library), Welsh Newspapers Online and Welsh Journals Online (National Library of Wales), and the National Terminology Portal (Bangor University).
In 2011, collaborative work began to convert the Dictionary data so that it could be used in the XML-based iLEX dictionary writing system, as well as to produce an online dictionary. After three years of work, on 26 June 2014, GPC Online was launche |
https://en.wikipedia.org/wiki/Climm |
climm (previously mICQ) is a free CLI-based instant messaging client that runs on a wide variety of platforms, including AmigaOS, BeOS, Windows (using either Cygwin or MinGW), OS X, NetBSD/OpenBSD/FreeBSD, Linux, Solaris, HP-UX, and AIX.
Functionality
climm has many of the features the official ICQ client has, and more:
It has support for SSL-encrypted direct connection compatible with licq and SIM.
It supports OTR encrypted messages.
It is internationalized; German, English, and other translations are available, and it supports sending and receiving acknowledged and non-acknowledged Unicode-encoded messages (it even understands UTF-8 messages for message types the ICQ protocol does not use them for).
It is capable of running several UINs at the same time and is very configurable (e.g. different colors for incoming messages from different contacts or for different accounts).
Due to its command-line interface, it has good usability for blind users through text-to-speech interfaces or Braille devices.
climm also supports basic functionality of the XMPP protocol.
History
Climm was originally developed as mICQ by Matt D. Smith as public domain software. Starting with mICQ 0.4.8 it was licensed under the GPLv2, not much of the original PD code remained since then. All later additions were made by Rüdiger Kuhlmann, in particular, the support for the ICQ v8 protocol. mICQ was renamed to climm ("Command Line Interface Multi Messenger") with version change to 0.6. CLimm was relicensed to include the OpenSSL exception.
See also
Comparison of instant messaging clients |
https://en.wikipedia.org/wiki/Index%20of%20telephone-related%20articles | These are some of the links to articles that are telephone related.
0-9
116 telephone number
800 number
A-F
Alexander Graham Bell
Answering machine
Antonio Meucci
Area code
Bell labs
Bell System
Call Login Systems
Carterfone
Cell site
Cellular network
Charles Bourseul
Cordless telephone
Martin Cooper
Demon Dialing
Dial tone
Elisha Gray
Elisha Gray and Alexander Bell telephone controversy
Emergency phone
Emile Berliner
Fax
Federal telephone excise tax
Francis Blake (telephone)
G-L
Geographic number
Harmonised service of social value
History of mobile phones
History of the telephone
Telephone in United States history
Hybrid routing
Innocenzo Manzetti
Invention of the telephone
Jipp curve
Local loop
M-R
Mobile phone
Philipp Reis
Phreaking
Plain old telephone service (POTS)
Private branch exchange
Public switched telephone network
Rate center
Regional Bell Operating Company
Ringaround
S-Z
Satellite phone
Sidetone
Telecommunications
Telephone
Telephone call
Telephone directory
Telephone exchange
Telephone line
Telephone newspaper
Telephone number
Telephone switchboard
Telephone tapping
Telephony
Thomas Edison
Timeline of the telephone
Tip and ring (Wiring terminology)
Toll-free telephone number
Zone Usage Measurement
See also
Telephony
Telecommunications equipment
Telephone connectors
Telephone directory publishing companies
Telephone directory publishing companies of the United States
Telephone exchanges
Telephone numbers |
https://en.wikipedia.org/wiki/Bick%27s%20Pickle | Bick's is a Canadian pickle producer originally based out of Scarborough, Ontario. The brand is now sold in Canada by U.S.-based The J.M. Smucker Co.
Bick's emerged in 1951 in the Toronto area when local farmers George and Lena Bick and their sons Walter and Thomas began to pickle the cucumbers produced on their Knollview farm. Beginning as a small operation of 60,000 jars, the Bicks produced 12 million jars in 1960. The business was sold in 1966 to Kraft Foods Canada and later became part of International Multifoods.
Walter Bick, one of the founders of Bick's Pickle, died on October 17, 2011, at the age of 94. Walter left behind four children, thirteen grandchildren and seven great-grandchildren.
For 50 years, the plant was a large commercial operation in the Scarborough City Centre area. However, the pickling and brining operations moved to Delhi, Ontario, in 1998 and remaining production to Dunnville, Ontario, in 2001.
In 2004, The J.M. Smucker Company acquired Bick's after it merged with International Multifoods. In 2010, Smuckers announced the closure of both Ontario facilities and thus brought an end to Bick's production in Canada. Since 2011, Bick's products are imported from the United States and marketed by the company's Markham, Ontario, based head office.
The former plant at 333 Progress Avenue is now used by paperboard and recycling firm Atlantic Packaging. |
https://en.wikipedia.org/wiki/Otfried%20Cheong | Otfried Cheong (formerly Otfried Schwarzkopf) is a German computational geometer working in South Korea at KAIST. He is known as one of the authors of the widely used computational geometry textbook Computational Geometry: Algorithms and Applications (with Mark de Berg, Marc van Kreveld, and Mark Overmars) and as the developer of Ipe, a vector graphics editor.
Cheong completed his doctorate from the Free University of Berlin in 1992 under the supervision of Helmut Alt.
He joined KAIST in 2005, after previously holding positions at Utrecht University, Pohang University of Science and Technology, Hong Kong University of Science and Technology, and the Eindhoven University of Technology. Cheong was co-chair of the Symposium on Computational Geometry in 2006, with Nina Amenta.
In 2017 he was recognized by the Association for Computing Machinery as a Distinguished Scientist. |
https://en.wikipedia.org/wiki/Class%20A%20surface | In automotive design, a class A surface is any of a set of freeform surfaces of high efficiency and quality. Although, strictly, it is nothing more than saying the surfaces have curvature and tangency alignment – to ideal aesthetical reflection quality, many people interpret class A surfaces to have G2 (or even G3) curvature continuity to one another (see free form surface modelling).
Class A surfacing is done using computer-aided industrial design applications. Class A surface modellers are also called "digital sculptors" in the industry. Industrial designers develop their design styling through the A-Surface, the physical surface the end user can feel, touch, see etc.
Application
A common method of working is to start with a prototype model and produce smooth mathematical Class A surfaces to describe the product's outer body. From this the production of tools and inspection of finished parts can be carried out. Class A surfacing complements the prototype modelling stage by reducing time and increasing control over design iterations.
Class A surfaces can be defined as any surface, that has styling intent, that is either seen, touched, or both and mathematically meets the definition for Bézier.
Automotive design application
In automotive design application Class A surfaces are created on all visible exterior surfaces (ex; body panels, bumper, grill, lights etc.) and all visible surfaces of see-touch & feel parts in interior (ex: Dashboard, seats, door pads etc.). This can also include beauty covers in the engine compartment, mud flaps, trunk panels and carpeting.
Product design application
In the product design realm, Class A surfacing can be applied to such things like housing for industrial appliances that are injection moulded, home appliances, highly aesthetic plastic packaging defined by highly organic surfaces, toys or furniture. Among the most famous users of Autodesk Alias software in product design is Apple.
Aerospace design application
Aerospace |
https://en.wikipedia.org/wiki/Facebook | Facebook is an online social media and social networking service owned by American technology giant Meta Platforms. Created in 2004 by Mark Zuckerberg with four other Harvard College students and roommates Eduardo Saverin, Andrew McCollum, Dustin Moskovitz, and Chris Hughes, its name derives from the face book directories often given to American university students. Membership was initially limited to Harvard students, gradually expanding to other North American universities. Since 2006, Facebook allows everyone to register from 13 years old (or older), except in the case of a handful of nations, where the age limit is 14 years. , Facebook claimed 3 billion monthly active users, and ranked third worldwide among the most visited websites. It was the most downloaded mobile app of the 2010s.
Facebook can be accessed from devices with Internet connectivity, such as personal computers, tablets and smartphones. After registering, users can create a profile revealing information about themselves. They can post text, photos and multimedia which are shared with any other users who have agreed to be their "friend" or, with different privacy settings, publicly. Users can also communicate directly with each other with Messenger, join common-interest groups, and receive notifications on the activities of their Facebook friends and the pages they follow.
The subject of numerous controversies, Facebook has often been criticized over issues such as user privacy (as with the Cambridge Analytica data scandal), political manipulation (as with the 2016 U.S. elections) and mass surveillance. Facebook has also been subject to criticism over psychological effects such as addiction and low self-esteem, and various controversies over content such as fake news, conspiracy theories, copyright infringement, and hate speech. Commentators have accused Facebook of willingly facilitating the spread of such content, as well as exaggerating its number of users to appeal to advertisers.
History
2 |
https://en.wikipedia.org/wiki/Homeostatic%20capacity | Homeostatic capacity refers to the capability of systems to self-stabilize in response to external forces or stressors, or more simply the capability of systems to maintain homeostasis. For living organisms, it is life's foundational trait, consisting of a hierarchy and network of traits endowed by nature and shaped by natural selection. Homeostatic capacity comprises a multidimensional network of traits and operates at all scales of biology systems levels including molecular, cellular, physiological, and organismal.
Human homeostatic capacity
In the context of human beings, homeostatic capacity refers to the inherent ability of the body to self-stabilize in response to external and internal stimuli. Homeostatic capacity of the human body erodes with age.
Homeostatic capacity and aging
A hypothesis proffered by the proponents of the Palo Alto Longevity Prize is that the array of ailments associated with aging may be epiphenomena of eroding homeostatic capacity and the process of aging may be halted or reversed by restoring homeostatic capacity to that of a healthy young adult.
See also
Senescence |
https://en.wikipedia.org/wiki/Forensic%20search | Forensic search is an emerging field of computer forensics. Forensic search focuses on user created data such as email files, cell phone records, office documents, PDFs and other files that are easily interpreted by a person.
Forensic search differs from computer forensic analysis in that it does not seek to review or analyze the lower level system files such as the registry, link files or disk level issues more commonly associated with traditional computer forensic analysis.
Purpose
Forensic search has emerged due to a number of factors including:
Improvements in technologies to enable lesser qualified users to undertake search and analysis of data that would have previously been undertaken only by a computer forensic expert. (This trend can be seen in many industries).
A need to reduce the high cost of undertaking a full computer forensic analysis of a user's computer, when in most cases the evidence found in the user created data is most useful and all that is required.
The rise of Cloud computing which has seen a move away from data storage on local computer hardware to data storage in any number of remote locations.
A lack of qualified computer forensic experts
The need to address the backlog of cases in most policing agencies where computer-based information requires review.
The need to involve other types of expertise for proper assessment of evidence, e.g. knowledge of accounting regulations, legal knowledge, etc.
Objectives
The objective of forensic search software is to allow a person with only a general knowledge of computers, but skilled in document review or investigation techniques, to undertake and search user created electronically stored information (ESI). Data that is typically considered to be user created ESI is made up of emails, documents, pictures and other file types created by a user, as opposed to data created by the computer's operating system (i.e. registry files, link files, unallocated space. These are controlled or created |
https://en.wikipedia.org/wiki/Dell%20EMC%20Data%20Domain | Dell EMC Data Domain was Dell EMC’s data deduplication storage system. Development began with the founding of Data Domain, and continued since that company’s acquisition by EMC Corporation (and EMC’s later merger with Dell to form Dell EMC).
History
The technology started in a separate company, which was then acquired and re-branded twice.
Data Domain Corporation
The Data Domain Corporation was founded by Kai Li, Ben Zhu, and Brian Biles in 2001 as a company specializing in target-based data deduplication products for disk-based backup.
Hugo Patterson joined as chief architect 3 months after initial funding.
The company started operations in a series of venture capital offices around Palo Alto, California, pre-funding at U.S. Venture Partners, where Zhu was an entrepreneur in residence (EIR), then at New Enterprise Associates (NEA), where Li was an EIR, and post-funding at Greylock Partners.
NEA and Greylock provided Series A funding in 2002.
The first product revenue was realized in the beginning of 2004.
Funding, IPO and Acquisition
NEA and Greylock led the company’s $9.3 million Series A funding round in 2002. Sutter Hill Ventures led its $17 million Series B funding round in 2003, joined again by NEA and Greylock. Through 2005, the three companies invested a total of $40 million in Data Domain.
The company had their initial public offering on June 27, 2007, with a total market capitalization of $776.5 million, above its forecast range despite years of losses. This put the stock price at $15 per share, above the forecasted range of $11.50 to $13.50. The company’s market capitalization was $776.5 million at the time of the IPO. It was listed on Nasdaq with symbol DDUP.
EMC Data Domain
In May 2009, NetApp announced it would acquire Data Domain for about $1.5 billion. In June 2009, EMC Corporation announced their intention to acquire Data Domain Corp for $2.4 billion, outbidding the previous offer. In July, the two companies agreed to the acquisition. Pos |
https://en.wikipedia.org/wiki/Average%20order%20of%20an%20arithmetic%20function | In number theory, an average order of an arithmetic function is some simpler or better-understood function which takes the same values "on average".
Let be an arithmetic function. We say that an average order of is if
as tends to infinity.
It is conventional to choose an approximating function that is continuous and monotone. But even so an average order is of course not unique.
In cases where the limit
exists, it is said that has a mean value (average value) .
Examples
An average order of , the number of divisors of , is ;
An average order of , the sum of divisors of , is ;
An average order of , Euler's totient function of , is ;
An average order of , the number of ways of expressing as a sum of two squares, is ;
The average order of representations of a natural number as a sum of three squares is ;
The average number of decompositions of a natural number into a sum of one or more consecutive prime numbers is ;
An average order of , the number of distinct prime factors of , is ;
An average order of , the number of prime factors of , is ;
The prime number theorem is equivalent to the statement that the von Mangoldt function has average order 1;
An average value of , the Möbius function, is zero; this is again equivalent to the prime number theorem.
Calculating mean values using Dirichlet series
In case is of the form
for some arithmetic function , one has,
Generalized identities of the previous form are found here. This identity often provides a practical way to calculate the mean value in terms of the Riemann zeta function. This is illustrated in the following example.
The density of the k-th power free integers in
For an integer the set of k-th-power-free integers is
We calculate the natural density of these numbers in , that is, the average value of , denoted by , in terms of the zeta function.
The function is multiplicative, and since it is bounded by 1, its Dirichlet series converges absolutely in the half-plane , and there ha |
https://en.wikipedia.org/wiki/Greek%20numerals | Greek numerals, also known as Ionic, Ionian, Milesian, or Alexandrian numerals, are a system of writing numbers using the letters of the Greek alphabet. In modern Greece, they are still used for ordinal numbers and in contexts similar to those in which Roman numerals are still used in the Western world. For ordinary cardinal numbers, however, modern Greece uses Arabic numerals.
History
The Minoan and Mycenaean civilizations' Linear A and Linear B alphabets used a different system, called Aegean numerals, which included number-only symbols for powers of ten: = 1, = 10, = 100, = 1000, and = 10000.
Attic numerals composed another system that came into use perhaps in the 7th century BCE. They were acrophonic, derived (after the initial one) from the first letters of the names of the numbers represented. They ran = 1, = 5, = 10, = 100, = 1,000, and = 10,000. The numbers 50, 500, 5,000, and 50,000 were represented by the letter with minuscule powers of ten written in the top right corner: , , , and . One-half was represented by (left half of a full circle) and one-quarter by ɔ (right side of a full circle). The same system was used outside of Attica, but the symbols varied with the local alphabets, for example, 1,000 was in Boeotia.
The present system probably developed around Miletus in Ionia. 19th century classicists placed its development in the 3rd century BCE, the occasion of its first widespread use. More thorough modern archaeology has caused the date to be pushed back at least to the 5th century BCE, a little before Athens abandoned its pre-Eucleidean alphabet in favour of Miletus's in 402 BCE, and it may predate that by a century or two. The present system uses the 24 letters adopted under Eucleides, as well as three Phoenician and Ionic ones that had not been dropped from the Athenian alphabet (although kept for numbers): digamma, koppa, and sampi. The position of those characters within the numbering system imply that the first two were still |
https://en.wikipedia.org/wiki/Johansen%20test | In statistics, the Johansen test, named after Søren Johansen, is a procedure for testing cointegration of several, say k, I(1) time series. This test permits more than one cointegrating relationship so is more generally applicable than the Engle–Granger test which is based on the Dickey–Fuller (or the augmented) test for unit roots in the residuals from a single (estimated) cointegrating relationship.
There are two types of Johansen test, either with trace or with eigenvalue, and the inferences might be a little bit different. The null hypothesis for the trace test is that the number of cointegration vectors is r = r* < k, vs. the alternative that r = k. Testing proceeds sequentially for r* = 1,2, etc. and the first non-rejection of the null is taken as an estimate of r. The null hypothesis for the "maximum eigenvalue" test is as for the trace test but the alternative is r = r* + 1 and, again, testing proceeds sequentially for r* = 1,2,etc., with the first non-rejection used as an estimator for r.
Just like a unit root test, there can be a constant term, a trend term, both, or neither in the model. For a general VAR(p) model:
There are two possible specifications for error correction: that is, two vector error correction models (VECM):
1. The longrun VECM:
where
2. The transitory VECM:
where
Be aware that the two are the same. In both VECM,
Inferences are drawn on Π, and they will be the same, so is the explanatory power. |
https://en.wikipedia.org/wiki/Algorithms%20for%20Recovery%20and%20Isolation%20Exploiting%20Semantics | In computer science, Algorithms for Recovery and Isolation Exploiting Semantics, or ARIES is a recovery algorithm designed to work with a no-force, steal database approach; it is used by IBM Db2, Microsoft SQL Server and many other database systems. IBM Fellow Dr. C. Mohan is the primary inventor of the ARIES family of algorithms.
Three main principles lie behind ARIES
Write-ahead logging: Any change to an object is first recorded in the log, and the log must be written to stable storage before changes to the object are written to disk.
Repeating history during Redo: On restart after a crash, ARIES retraces the actions of a database before the crash and brings the system back to the exact state that it was in before the crash. Then it undoes the transactions still active at crash time.
Logging changes during Undo: Changes made to the database while undoing transactions are logged to ensure such an action isn't repeated in the event of repeated restarts.
Logging
The ARIES algorithm relies on logging of all database operations with ascending Sequence Numbers. Usually the resulting logfile is stored on so-called "stable storage", that is a storage medium that is assumed to survive crashes and hardware failures.
To gather the necessary information for the logs, two data structures have to be maintained: the dirty page table (DPT) and the transaction table (TT).
The dirty page table keeps record of all the pages that have been modified, and not yet written to disk, and the first Sequence Number that caused that page to become dirty. The transaction table contains all currently running transactions and the Sequence Number of the last log entry they created.
We create log records of the form (Sequence Number, Transaction ID, Page ID, Redo, Undo, Previous Sequence Number). The Redo and Undo fields keep information about the changes this log record saves and how to undo them. The Previous Sequence Number is a reference to the previous log record that was created |
https://en.wikipedia.org/wiki/List%20of%20Burundian%20flags | This is a list of the flags of Burundi. for the national flag, see Flag of Burundi.
National flag
Ethnic group flags
Political party flags
Historical flags
See also
Flag of Burundi
Coat of arms of Burundi |
https://en.wikipedia.org/wiki/Gn15 | Gn15 is a rail modelling scale, using G scale 1:22.5 scale trains running on H0/00 gauge () track, representing minimum gauge and miniature railways. Typical models built are between 1:20.3 and 1:24, or up to 1:29.
NEM 010 specification defines IIp for modelling gauge.
History
Gn15 modeling is a relatively new phenomenon in the model railroading world. While the idea of this scale has existed for some time, as evidenced by the early efforts of Marc Horovitz, editor of Garden Railways magazine, Gn15 did not gain any measure of popularity until the Sidelines range of models. Following the advent of these kits, a few other lines of kits became available.
Initial community development took place on Yahoo email groups, but these have been superseded by the forums at Gn15.info as the primary form of communication between the far flung practitioners of this scale.
09, GNine and related scales
Alongside Gn15 other modeling scales have developed to cover both the modelling of minimum gauge lines in scales smaller than G, and 'miniature' lines (less than ) in G scale.
O9 or On15 is the use of N gauge track in 7mm scale to represent a 'minimum gauge' line. In comparison, GNine is the use of 9mm track to represent 'miniature' lines. GNine is a 'flexible' term for scale, referring to modelling using garden railway scales and N gauge track. GNine models can be built to scales between 7/8" and 1:35 representing anything between gauge and miniature railways. |
https://en.wikipedia.org/wiki/Sound%20map | Sound maps are digital geographical maps that put emphasis on the sonic representation of a specific location. Sound maps are created by associating landmarks (streets in a city, train stations, stores, pathways, factories, oil pumps, etc.) and soundscapes.
The term “soundscape” refers to the sonic environment of a specific locale. It may also refer to actual environments, or to abstract constructions such as musical compositions and tape montages, particularly when considered as an artificial environment. The objective of sound maps is to represent a specific environment using its soundscape as primary references as opposed to visual cues. Sound maps are in many ways the most effective auditory archive of an environment. Sound maps are similar to sound walks which are a form of active participation in the soundscape. Soundwalks and indeed, sound maps encourage the participants to listen discriminatively, and moreover, to make critical judgments about the sounds heard and their contribution to the balance or imbalance of the sonic environment. However, soundwalks will plot out a route for the user to follow and give guidance as to what the user may be hearing at each checkpoint. Sound maps, on the other hand, have specific soundscapes recorded that users can listen to at each checkpoint.
History / Background
The theoretical framework upon which sound maps are based derive from earlier research on acoustic ecology and soundscapes, the later being a term first coined by researcher and music composer R. Murray Schafer in the 1960s. Looking to challenge traditional ideas of recording reality, Schafer, along with several college music composers such as Barry Truax and Hildegard Westerkamp, funded the World Soundscape Project, an ambitious sound recording project that led the team based in Simon Fraser University to travel within Canada and out in Europe to collect data on local soundscapes. The sounds that they recorded were used to build a database of locales not bas |
https://en.wikipedia.org/wiki/Alphalipothrixvirus | Alphalipothrixvirus is a genus of viruses in the family Lipothrixviridae. Archaea serve as natural hosts. The genus contains two species.
Taxonomy
The following two species are assigned to the genus
Alphalipothrixvirus SBFV2
Alphalipothrixvirus SFV1
Structure
Life cycle |
https://en.wikipedia.org/wiki/Level%20%28logarithmic%20quantity%29 | In science and engineering, a power level and a field level (also called a root-power level) are logarithmic magnitudes of certain quantities referenced to a standard reference value of the same type.
A power level is a logarithmic quantity used to measure power, power density or sometimes energy, with commonly used unit decibel (dB).
A field level (or root-power level) is a logarithmic quantity used to measure quantities of which the square is typically proportional to power (for instance, the square of voltage is proportional to power by the inverse of the conductor's resistance), etc., with commonly used units neper (Np) or decibel (dB).
The type of level and choice of units indicate the scaling of the logarithm of the ratio between the quantity and its reference value, though a logarithm may be considered to be a dimensionless quantity. The reference values for each type of quantity are often specified by international standards.
Power and field levels are used in electronic engineering, telecommunications, acoustics and related disciplines. Power levels are used for signal power, noise power, sound power, sound exposure, etc. Field levels are used for voltage, current, sound pressure.
Power level
Level of a power quantity, denoted LP, is defined by
where
P is the power quantity;
P0 is the reference value of P.
Field (or root-power) level
The level of a root-power quantity (also known as a field quantity), denoted LF, is defined by
where
F is the root-power quantity, proportional to the square root of power quantity;
F0 is the reference value of F.
If the power quantity P is proportional to F2, and if the reference value of the power quantity, P0, is in the same proportion to F02, the levels LF and LP are equal.
The neper, bel, and decibel (one tenth of a bel) are units of level that are often applied to such quantities as power, intensity, or gain. The neper, bel, and decibel are related by
;
.
Standards
Level and its units are define |
https://en.wikipedia.org/wiki/Da%20Vinci%20Systems | da Vinci Systems was an American digital cinema company founded in 1984 in Coral Springs, Florida as a spinoff of Video Tape Associates. It was known for its hardware-based color correction products, GPU-based color grading, digital mastering systems, and film restoration and remastering systems. It was one of the earliest pioneers in post-production products. The company was owned by Dynatech Corporation (Acterna after 2000) for the majority of its lifespan until being bought by JDS Uniphase in 2005 and by Blackmagic Design in 2009.
Company history
In 1982, Video Tape Associates (VTA), a Hollywood, Florida-based production/post-production facility, began developing the Wiz for internal use and introduced it to the public the following year. The Wiz controlled early telecines such as the RCA FR-35 and the Bosch FDL 60 and offered basic primary and secondary color correction. The American post-production facilities company EDITEL Group asked VTA to build multiple Wiz systems for them. Fifteen units were made and subsequently purchased by other post-production facilities across the country. The Wiz served as a major inspiration/prototype for what would become the da Vinci Classic.
In 1984, VTA Technologies, the research and development division of VTA Post, broke away from its parent company to become da Vinci Systems, Inc. One of its four founders was Bob Hemsky. The da Vinci was the only film-to-tape or tape-to-tape color correction system on the market that offered the capability to create a basic rectangular window shape isolating a secondary color correction. In 1986, da Vinci was acquired by Dynatech Corporation and managed within their Utah Scientific business. Two years later, da Vinci Systems, LLC became its own entity as one of roughly eight video manufacturing companies within the Dynatech Video Group. In 1998, da Vinci Academy was formed to provide training to the growing number of aspiring colorists. The following year, da Vinci acquired Nevada-based S |
https://en.wikipedia.org/wiki/Univa%20Grid%20Engine | Univa Grid Engine (UGE) is a batch-queuing system, forked from Sun Grid Engine (SGE). The software schedules resources in a data center applying user-configurable policies to help improve resource sharing and throughput by maximizing resource utilization. The product can be deployed to run on-premises, using IaaS cloud computing or in a hybrid cloud environment.
History
The roots of Grid Engine as a commercial product date back to 1993 (under the names CODINE and later, in a variation of the product, GRD). A more comprehensive genealogy of the product is described in Sun Grid Engine. Grid Engine was first distributed by Genias Software and from 1999, after a company merger, by Gridware, Inc. In 2000, Sun Microsystems acquired Gridware. Sun renamed CODINE/GRD as Sun Grid Engine later that year, and released it as open-source in 2001.
In 2010, Oracle Corporation acquired Sun and subsequently renamed SGE to Oracle Grid Engine. Oracle Grid Engine (6.2u6) moved to a closed-source model providing binaries with the distribution but no source code. As a result, the project's open-source repository no longer reflected changes made by Oracle and users were prevented from contributing code changes. In response to this, the Grid Engine community started the Open Grid Scheduler and the Son of Grid Engine projects to continue to develop and maintain a free implementation of Grid Engine. The University of Michigan has been maintaining the Son of Grid Engine code publicly since 2019.
On January 18, 2011, Univa announced that it had hired the principal engineers from the Sun Grid Engine team. Univa Grid Engine development is led by CTO Fritz Ferstl, who founded the Grid Engine project and ran the business within Sun/Oracle for the past 10 years.
On October 22, 2013, Univa announced that it had acquired Oracle Grid Engine assets and intellectual property, making it the sole commercial provider of Grid Engine software.
Between 2011 and 2013 Univa added new capabilities to Univ |
https://en.wikipedia.org/wiki/Rydberg%20state | The Rydberg states of an atom or molecule are electronically excited states with energies that follow the Rydberg formula as they converge on an ionic state with an ionization energy. Although the Rydberg formula was developed to describe atomic energy levels, it has been used to describe many other systems that have electronic structure roughly similar to atomic hydrogen. In general, at sufficiently high principal quantum numbers, an excited electron-ionic core system will have the general character of a hydrogenic system and the energy levels will follow the Rydberg formula. Rydberg states have energies converging on the energy of the ion. The ionization energy threshold is the energy required to completely liberate an electron from the ionic core of an atom or molecule. In practice, a Rydberg wave packet is created by a laser pulse on a hydrogenic atom and thus populates a superposition of Rydberg states. Modern investigations using pump-probe experiments show molecular pathways – e.g. dissociation of (NO)2 – via these special states.
Rydberg series
Rydberg series describe the energy levels associated with partially removing an electron from the ionic core. Each Rydberg series converges on an ionization energy threshold associated with a particular ionic core configuration. These quantized Rydberg energy levels can be associated with the quasiclassical Bohr atomic picture. The closer you get to the ionization threshold energy, the higher the principal quantum number, and the smaller the energy difference between "near threshold Rydberg states." As the electron is promoted to higher energy levels, the spatial excursion of the electron from the ionic core increases and the system is more like the Bohr quasiclassical picture.
Energy of Rydberg states
The energy of Rydberg states can be refined by including a correction called the quantum defect in the Rydberg formula. The "quantum defect" correction is associated with the presence of a distributed ionic core. Eve |
https://en.wikipedia.org/wiki/Backdrive | A backdrive is a component used in reverse to obtain its input from its output. This extends to many concepts and systems from thought based to practical mechanical applications.
Not every system can be backdriven. A DC electrical generator can be implemented by backdriving a DC electric motor, however a worm drive works only in one direction.
Example: A CNC vertical mill has a vertical lead screw on the Z-axis. A low lead screw pitch (i.e. 5 turns per inch or fewer) means when the driving motor power is removed such as by turning the machine off, the weight of the spindle will cause the lead screw to rotate as the spindle motor falls down. The solution to prevent back-driving is to use a finer (higher) lead screw pitch (i.e. 10tpi or greater) or have a locking mechanism.
Another example is the practice to add swivel caster wheels on a mobile robot, so that humans can push away the robot when it comes too close.
Mechanical engineering |
https://en.wikipedia.org/wiki/Fringe%20shift | In interferometry experiments such as the Michelson–Morley experiment, a fringe shift is the behavior of a pattern of “fringes” when the phase relationship between the component sources change.
A fringe pattern can be created in a number of ways but the stable fringe pattern found in the Michelson type interferometers is caused by the separation of the original source into two separate beams and then recombining them at differing angles of incidence on a viewing surface.
The interaction of the waves on a viewing surface alternates between constructive interference and destructive interference causing alternating lines of dark and light. In the example of a Michelson Interferometer, a single fringe represents one wavelength of the source light and is measured from the center of one bright line to the center of the next. The physical width of a fringe is governed by the difference in the angles of incidence of the component beams of light, but regardless of a fringe's physical width, it still represents a single wavelength of light.
Historical Context
In the 1887 Michelson–Morley experiment, the round trip distance that the two beams traveled down the precisely equal arms was expected to be made unequal because of the, now deprecated, idea that light is constrained to travel as a mechanical wave at the speed C only in the rest frame of the luminiferous aether.
The Earth's presumed motion through that frame was believed to cause a local aether "wind" in the moving frame of the interferometer like a car passing through still air creates an apparent wind for those inside. It is crucial to avoid the Historian's fallacy and note that these experimenters did not expect that a mechanical wave would travel varying speeds within a homogenous isotropic medium of aether. Waves have been studied since antiquity and mathematically at least since Jean le Rond d'Alembert in the 1700s. Our modern understanding of the constancy of light, however, grants the additional, new, "n |
https://en.wikipedia.org/wiki/Human%20papillomavirus%20infection | Human papillomavirus infection (HPV infection) is caused by a DNA virus from the Papillomaviridae family. Many HPV infections cause no symptoms and 90% resolve spontaneously within two years. In some cases, an HPV infection persists and results in either warts or precancerous lesions. These lesions, depending on the site affected, increase the risk of cancer of the cervix, vulva, vagina, penis, anus, mouth, tonsils, or throat. Nearly all cervical cancer is due to HPV and two strains – HPV16 and HPV18 – which account for 70% of cases. HPV16 is responsible for almost 90% of HPV-positive oropharyngeal cancers. Between 60% and 90% of the other cancers listed above are also linked to HPV. HPV6 and HPV11 are common causes of genital warts and laryngeal papillomatosis.
An HPV infection is caused by the human papillomavirus, a DNA virus from the papillomavirus family. Over 200 types have been described. An individual can become infected with more than one type of HPV, and the disease is only known to affect humans. More than 40 types may be spread through sexual contact and infect the anus and genitals. Risk factors for persistent infection by sexually transmitted types include early age of first sexual intercourse, multiple sexual partners, smoking, and poor immune function. These types are typically spread by sustained direct skin-to-skin contact, with vaginal and anal sex being the most common methods. HPV infection can also spread from a mother to baby during pregnancy. There is no evidence that HPV can spread via common items like toilet seats, but the types that cause warts may spread via surfaces such as floors. HPV is not killed by common hand sanitizers and disinfectants, increasing the possibility of the virus being transferred via non-living infectious agents called fomites.
HPV vaccines can prevent the most common types of infection. To be most effective, inoculation should occur before the onset of sexual activity, and are therefore recommended between the ag |
https://en.wikipedia.org/wiki/Monogenism | Monogenism or sometimes monogenesis is the theory of human origins which posits a common descent for all human races. The negation of monogenism is polygenism. This issue was hotly debated in the Western world in the nineteenth century, as the assumptions of scientific racism came under scrutiny both from religious groups and in the light of developments in the life sciences and human science. It was integral to the early conceptions of ethnology.
Modern scientific views favor this theory, with the most widely accepted model for human origins being the "Out of Africa" theory.
In the Abrahamic religions
The belief that all humans are descended from Adam is central to traditional Judaism, Christianity and Islam. Christian monogenism played an important role in the development of an African-American literature on race, linked to theology rather than science, up to the time of Martin Delany and his Principia of Ethnology (1879). Scriptural ethnology is a term applied to debate and research on the biblical accounts, both of the early patriarchs and migration after Noah's Flood, to explain the diverse peoples of the world. Monogenism as a Bible-based theory required both the completeness of the narratives and the fullness of their power of explanation. These time-honored debates were sharpened by the rise of polygenist skeptical claims; when Louis Agassiz set out his polygenist views in 1847, they were opposed on biblical grounds by John Bachman, and by Thomas Smyth in his Unity of the Human Races. The debates also saw the participation of Delany, and George Washington Williams defended monogenesis as the starting point of his pioneer history of African-Americans.
Environmentalist monogenism
Environmentalist monogenism describes a theory current in the first half of the nineteenth century, in particular, according to which there was a single human origin, but that subsequent migration of groups of humans had subjected them to different environmental conditions.
Envir |
https://en.wikipedia.org/wiki/Congenital%20fiber%20type%20disproportion | Congenital fiber type disproportion (CFTD) is an inherited form of myopathy with small type 1 muscle fibers that may occur in a number of neurological disorders. It has a relatively good outcome and follows a stable course. While the exact genetics is unclear, there is an association with mutations in the genes TPM3, ACTA1 and SEPN1. It is a rare condition.
History
The condition was named by M. H. Brooke in 1973. |
https://en.wikipedia.org/wiki/NFE2 |
Transcription factor NF-E2 45 kDa subunit is a protein that in humans is encoded by the NFE2 gene.
It is involved in megakaryocyte production.
Interactions
NFE2 has been shown to interact with CREB-binding protein. |
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