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https://en.wikipedia.org/wiki/Protoplasm | Protoplasm (; ) is the living part of a cell that is surrounded by a plasma membrane. It is a mixture of small molecules such as ions, monosaccharides, amino acids, and macromolecules such as proteins, polysaccharides, lipids, etc.
In some definitions, it is a general term for the cytoplasm (e.g., Mohl, 1846), but for others, it also includes the nucleoplasm (e.g., Strasburger, 1882). For Sharp (1921), "According to the older usage the extra-nuclear portion of the protoplast [the entire cell, excluding the cell wall] was called "protoplasm," but the nucleus also is composed of protoplasm, or living substance in its broader sense. The current consensus is to avoid this ambiguity by employing Strasburger's (1882) terms cytoplasm [coined by Kölliker (1863), originally as synonym for protoplasm] and nucleoplasm [term coined by van Beneden (1875), or karyoplasm, used by Flemming (1878)]." The cytoplasm definition of Strasburger excluded the plastids (Chromatoplasm).
Like the nucleus, whether to include the vacuole in the protoplasm concept is controversial.
Terminology
Besides "protoplasm", many other related terms and distinctions were used for the cell contents over time. These were as follows:
Urschleim (Oken, 1802, 1809),
Protoplasma (Purkinje, 1840, von Mohl, 1846),
Primordialschlauch (primordial utricle, von Mohl, 1846),
sarcode (Dujardin, 1835, 1841),
Cytoplasma (Kölliker, 1863),
Hautschicht/Körnerschicht (ectoplasm/endoplasm, Pringsheim, 1854; Hofmeister, 1867),
Grundsubstanz (ground substance, Cienkowski, 1863),
metaplasm/protoplasm (Hanstein, 1868),
deutoplasm/protoplasm (van Beneden, 1870),
bioplasm (Beale, 1872),
paraplasm/protoplasm (Kupffer, 1875),
inter-filar substance theory (Velten, 1876)
Hyaloplasma (Pfeffer, 1877),
Protoplast (Hanstein, 1880),
Enchylema/Hyaloplasma (Hanstein, 1880),
Kleinkörperchen or Mikrosomen (small bodies or microsomes, Hanstein, 1882),
paramitome (Flemming, 1882),
Idioplasma (Nageli, 1884),
Zwischensu |
https://en.wikipedia.org/wiki/Power%20Mac%20G5 | The Power Mac G5 is a series of personal computers designed, manufactured, and sold by Apple Computer, Inc. from 2003 to 2006 as part of the Power Mac series. When introduced, it was the most powerful computer in Apple's Macintosh lineup, and was marketed by the company as the world's first 64-bit desktop computer. It was also the first desktop computer from Apple to use an anodized aluminum alloy enclosure, and one of only three computers in Apple's lineup to utilize the PowerPC 970 CPU, the others being the iMac G5 and the Xserve G5.
Three generations of Power Mac G5 were released before it was discontinued as part of the Mac transition to Intel processors, making way for its replacement, the Mac Pro. The Mac Pro retained a variation of the G5's enclosure design for seven more years, making it among the longest-lived designs in Apple's history.
Introduction
Officially launched as part of Steve Jobs' keynote presentation at the Worldwide Developers Conference in June 2003, the Power Mac G5 was introduced with three models, sharing the same physical case, but differing in features and performance. Although somewhat larger than the G4 tower it replaced, the necessity for a complex cooling system meant that the G5 tower had room inside for only one optical drive and two hard drives.
Steve Jobs stated during his keynote presentation that the Power Mac G5 would reach 3 GHz "within 12 months." This would never come to pass; after three years, the G5 only reached 2.7 GHz before it was replaced by the Intel Xeon-based Mac Pro, which debuted with processors running at speeds of up to 3 GHz.
During the presentation, Apple also showed Virginia Tech's Mac OS X computer cluster supercomputer (a.k.a. supercluster) known as System X, consisting of 1,100 Power Mac G5 towers operating as processing nodes. The supercomputer managed to become one of the top five supercomputers that year. The computer was soon dismantled and replaced with a new cluster made of an equal number o |
https://en.wikipedia.org/wiki/Presentation%20Manager | Presentation Manager (PM) is the graphical user interface (GUI) that IBM and Microsoft introduced in version 1.1 of their operating system OS/2 in late 1988.
History
Microsoft began developing a graphic user interface (GUI) in 1981. After it persuaded IBM that the latter also needed a GUI, Presentation Manager (PM; codenamed Winthorn) was co-developed by Microsoft and IBM's Hursley Lab in 1987-1988. It was a cross between Microsoft Windows and IBM's mainframe graphical system (GDDM). Like Windows, it was message based and many of the messages were even identical, but there were a number of significant differences as well. Although Presentation Manager was designed to be very similar to the upcoming Windows 2.0 from the user's point of view, and Presentation Manager application structure was nearly identical to Windows application structure, source compatibility with Windows was not an objective. For Microsoft, the development of Presentation Manager was an opportunity to clean up some of the design mistakes of Windows. The two companies stated that Presentation Manager and Windows 2.0 would remain almost identical.
One of the most significant differences between Windows and PM was the coordinate system. While in Windows the 0,0 coordinate was located in the upper left corner, in PM it was in the lower left corner. Another difference was that all drawing operations went to the Device Context (DC) in Windows. PM also used DCs but there was an added level of abstraction called Presentation Space (PS). OS/2 also had more powerful drawing functions in its Graphics Programming Interface (GPI). Some of the GPI concepts (like viewing transforms) were later incorporated into Windows NT. The OS/2 programming model was thought to be cleaner, since there was no need to explicitly export the window procedure, no WinMain, and no non-standard function prologs and epilogs.
Parting ways
One of the most-cited reasons for the IBM-Microsoft split was the divergence of the APIs be |
https://en.wikipedia.org/wiki/Superstructure | A superstructure is an upward extension of an existing structure above a baseline. This term is applied to various kinds of physical structures such as buildings, bridges, or ships.
Aboard ships and large boats
On water craft, the superstructure consists of the parts of the ship or a boat, including sailboats, fishing boats, passenger ships, and submarines, that project above her main deck. This does not usually include its masts or any armament turrets. Note that, in modern times, turrets do not always carry naval artillery, they can also carry missile launchers and/or antisubmarine warfare weapons.
The size of a watercraft's superstructure can have many implications in the performance of ships and boats, since these structures can alter their structural rigidity, their displacements, and/or stability. These can be detrimental to any vessel's performance if they are taken into consideration incorrectly.
The height and the weight of superstructure on board a ship or a boat also affects the amount of freeboard that such a vessel requires along its sides, down to her waterline. In broad terms, the more and heavier superstructure that a ship possesses (as a fraction of her length), the less the freeboard that is needed.
Bridges
The span of a bridge, the portion that directly receives the live load, is referred to as the superstructure. In contrast, the abutment, piers, and other support structures are called the 'substructure'.
Earthquake protection
In order to improve the response during earthquakes of buildings and bridges, the superstructure may be separated from its foundation by various civil engineering mechanisms or machinery. All together, these implement the system of earthquake protection called base isolation.
References
External links
Building engineering
Ship compartments
Shipbuilding
Nautical terminology
Bridge components
de:Suprastruktur
id:Superstruktur
tr:Üstyapı |
https://en.wikipedia.org/wiki/Agar%20plate | An agar plate is a Petri dish that contains a growth medium solidified with agar, used to culture microorganisms. Sometimes selective compounds are added to influence growth, such as antibiotics.
Individual microorganisms placed on the plate will grow into individual colonies, each a clone genetically identical to the individual ancestor organism (except for the low, unavoidable rate of mutation). Thus, the plate can be used either to estimate the concentration of organisms in a liquid culture or a suitable dilution of that culture using a colony counter, or to generate genetically pure cultures from a mixed culture of genetically different organisms.
Several methods are available to plate out cells. One technique is known as "streaking". In this technique, a drop of the culture on the end of a thin, sterile loop of wire, sometimes known as an inoculator, is streaked across the surface of the agar leaving organisms behind, a higher number at the beginning of the streak and a lower number at the end. At some point during a successful "streak", the number of organisms deposited will be such that distinct individual colonies will grow in that area which may be removed for further culturing, using another sterile loop.
Another way of plating organisms, next to streaking, on agar plates is the spot analysis. This type of analysis is often used to check the viability of cells and performed with pinners (often also called froggers). A third used technique is the use of sterile glass beads to plate out cells. In this technique cells are grown in a liquid culture of which a small volume is pipetted on the agar plate and then spread out with the beads. Replica plating is another technique in order to plate out cells on agar plates. These four techniques are the most common, but others are also possible. It is crucial to work in a sterile manner in order to prevent contamination on the agar plates. Plating is thus often done in a laminar flow cabinet or on the working benc |
https://en.wikipedia.org/wiki/Isometry | In mathematics, an isometry (or congruence, or congruent transformation) is a distance-preserving transformation between metric spaces, usually assumed to be bijective. The word isometry is derived from the Ancient Greek: ἴσος isos meaning "equal", and μέτρον metron meaning "measure".
Introduction
Given a metric space (loosely, a set and a scheme for assigning distances between elements of the set), an isometry is a transformation which maps elements to the same or another metric space such that the distance between the image elements in the new metric space is equal to the distance between the elements in the original metric space.
In a two-dimensional or three-dimensional Euclidean space, two geometric figures are congruent if they are related by an isometry;
the isometry that relates them is either a rigid motion (translation or rotation), or a composition of a rigid motion and a reflection.
Isometries are often used in constructions where one space is embedded in another space. For instance, the completion of a metric space involves an isometry from into a quotient set of the space of Cauchy sequences on
The original space is thus isometrically isomorphic to a subspace of a complete metric space, and it is usually identified with this subspace.
Other embedding constructions show that every metric space is isometrically isomorphic to a closed subset of some normed vector space and that every complete metric space is isometrically isomorphic to a closed subset of some Banach space.
An isometric surjective linear operator on a Hilbert space is called a unitary operator.
Definition
Let and be metric spaces with metrics (e.g., distances) and
A map is called an isometry or distance preserving if for any one has
An isometry is automatically injective; otherwise two distinct points, a and b, could be mapped to the same point, thereby contradicting the coincidence axiom of the metric d.
This proof is similar to the proof that an order embedding be |
https://en.wikipedia.org/wiki/Coherent%20%28operating%20system%29 | Coherent is a clone of the Unix operating system for IBM PC compatibles and other microcomputers, developed and sold by the now-defunct Mark Williams Company (MWC). Historically, the operating system was a proprietary product, but it became open source in 2015, released under the BSD-3-Clause license.
Development
Coherent was not Unix; the Mark Williams Company had no rights to either the Unix trademark or the AT&T/Bell Labs source code. In the early years of its existence, MWC received a visit from an AT&T delegation looking to determine whether MWC was infringing on AT&T Unix property. The delegation included Dennis Ritchie, who concluded that "it was very hard to believe that Coherent and its basic applications were not created without considerable study of the OS code and details of its applications." However, he also stated that:
Much of the operating system was written by alumni from the University of Waterloo: Tom Duff, Dave Conroy, Randall Howard, Johann George, and Trevor John Thompson. Significant contributions were also made by people such as Nigel Bree (from Auckland, New Zealand), the later author of Ghost.
Versions
Coherent was originally written for the PDP-11 range of minicomputers in 1980, then ported to various early 1980s microcomputer systems including IBM PC compatibles and machines based on the Zilog Z8000 and Motorola 68000. Initially sold to OEMs, starting 1983 it was available on the consumer market from MWC directly. At this point, Coherent 2.3 offered roughly the functionality of Version 7 Unix on PC hardware, including the nroff formatter but not the BSD extensions offered by competing Unix/clone vendors; compared to its competitors, it was a small system distributed on only seven double-sided floppy disks, costing only US$500 for a license.
BYTE in 1984 called Coherent a "highly compatible UNIX Version 7 lookalike". In 1985 it criticized the difficulty of installation, but stated that "as a UNIX clone, Coherent is amazingly complete |
https://en.wikipedia.org/wiki/Voicemail | A voicemail system (also known as voice message or voice bank) is a computer-based system that allows users and subscribers to exchange personal voice messages; to select and deliver voice information; and to process transactions relating to individuals, organizations, products, and services, using an ordinary phone. The term is also used more broadly to denote any system of conveying a stored telecommunications voice messages, including using an answering machine. Most cell phone services offer voicemail as a basic feature; many corporate private branch exchanges include versatile internal voice-messaging services, and *98 vertical service code subscription is available to most individual and small business landline subscribers (in the US).
History
The term Voicemail was coined by Televoice International (later Voicemail International, or VMI) for their introduction of the first US-wide Voicemail service in 1980. Although VMI trademarked the term, it eventually became a generic term for automated voice services employing a telephone. Voicemail popularity continues today with Internet telephone services such as Skype, Google Voice and ATT that integrate voice, voicemail and text services for tablets and smartphones.
Voicemail systems were developed in the late 1970s by Voice Message Exchange (VMX). They became popular in the early 1980s when they were made available on PC-based boards. In September 2012 a report from USA Today and Vonage claimed that voicemail was in decline. The report said that the number of voicemail messages declined eight percent compared to 2011.
Features
Voicemail systems are designed to convey a caller's recorded audio message to a recipient. To do so they contain a user interface to select, play, and manage messages; a delivery method to either play or otherwise deliver the message; and a notification ability to inform the user of a waiting message. Most systems use phone networks, either cellular- or landline-based, as the conduit for |
https://en.wikipedia.org/wiki/Mastering%20%28audio%29 | Mastering, a form of audio post production, is the process of preparing and transferring recorded audio from a source containing the final mix to a data storage device (the master), the source from which all copies will be produced (via methods such as pressing, duplication or replication). In recent years, digital masters have become usual, although analog masters—such as audio tapes—are still being used by the manufacturing industry, particularly by a few engineers who specialize in analog mastering.
Mastering requires critical listening; however, software tools exist to facilitate the process. Results depend upon the intent of the engineer, their skills, the accuracy of the speaker monitors, and the listening environment. Mastering engineers often apply equalization and dynamic range compression in order to optimize sound translation on all playback systems. It is standard practice to make a copy of a master recording—known as a safety copy—in case the master is lost, damaged or stolen.
History
Pre-1940s
In the earliest days of the recording industry, all phases of the recording and mastering process were entirely achieved by mechanical processes. Performers sang and/or played into a large acoustic horn and the master recording was created by the direct transfer of acoustic energy from the diaphragm of the recording horn to the mastering lathe, typically located in an adjoining room. The cutting head, driven by the energy transferred from the horn, inscribed a modulated groove into the surface of a rotating cylinder or disc. These masters were usually made from either a soft metal alloy or from wax; this gave rise to the colloquial term waxing, referring to the cutting of a record.
After the introduction of the microphone and electronic amplifier in the mid-1920s, the mastering process became electro-mechanical, and electrically driven mastering lathes came into use for cutting master discs (the cylinder format by then having been superseded). Until the intro |
https://en.wikipedia.org/wiki/Nondestructive%20testing | Nondestructive testing (NDT) is any of a wide group of analysis techniques used in science and technology industry to evaluate the properties of a material, component or system without causing damage.
The terms nondestructive examination (NDE), nondestructive inspection (NDI), and nondestructive evaluation (NDE) are also commonly used to describe this technology.
Because NDT does not permanently alter the article being inspected, it is a highly valuable technique that can save both money and time in product evaluation, troubleshooting, and research. The six most frequently used NDT methods are eddy-current, magnetic-particle, liquid penetrant, radiographic, ultrasonic, and visual testing. NDT is commonly used in forensic engineering, mechanical engineering, petroleum engineering, electrical engineering, civil engineering, systems engineering, aeronautical engineering, medicine, and art. Innovations in the field of nondestructive testing have had a profound impact on medical imaging, including on echocardiography, medical ultrasonography, and digital radiography.
Non-Destructive Testing (NDT/ NDT testing) Techniques or Methodologies allow the investigator to carry out examinations without invading the integrity of the engineering specimen under observation while providing an elaborate view of the surface and structural discontinuities and obstructions. The personnel carrying out these methodologies require specialized NDT Training as they involve handling delicate equipment and subjective interpretation of the NDT inspection/NDT testing results.
NDT methods rely upon use of electromagnetic radiation, sound and other signal conversions to examine a wide variety of articles (metallic and non-metallic, food-product, artifacts and antiquities, infrastructure) for integrity, composition, or condition with no alteration of the article undergoing examination. Visual inspection (VT), the most commonly applied NDT method, is quite often enhanced by the use of magnificatio |
https://en.wikipedia.org/wiki/Tensor%20%28intrinsic%20definition%29 | In mathematics, the modern component-free approach to the theory of a tensor views a tensor as an abstract object, expressing some definite type of multilinear concept. Their properties can be derived from their definitions, as linear maps or more generally; and the rules for manipulations of tensors arise as an extension of linear algebra to multilinear algebra.
In differential geometry, an intrinsic geometric statement may be described by a tensor field on a manifold, and then doesn't need to make reference to coordinates at all. The same is true in general relativity, of tensor fields describing a physical property. The component-free approach is also used extensively in abstract algebra and homological algebra, where tensors arise naturally.
Note: This article assumes an understanding of the tensor product of vector spaces without chosen bases. An overview of the subject can be found in the main tensor article.
Definition via tensor products of vector spaces
Given a finite set of vector spaces over a common field F, one may form their tensor product , an element of which is termed a tensor.
A tensor on the vector space V is then defined to be an element of (i.e., a vector in) a vector space of the form:
where V∗ is the dual space of V.
If there are m copies of V and n copies of V∗ in our product, the tensor is said to be of and contravariant of order m and covariant of order n and of total order . The tensors of order zero are just the scalars (elements of the field F), those of contravariant order 1 are the vectors in V, and those of covariant order 1 are the one-forms in V∗ (for this reason, the elements of the last two spaces are often called the contravariant and covariant vectors). The space of all tensors of type is denoted
Example 1. The space of type tensors, is isomorphic in a natural way to the space of linear transformations from V to V.
Example 2. A bilinear form on a real vector space V, corresponds in a natural way to a type tensor |
https://en.wikipedia.org/wiki/2%20%2B%202%20%3D%205 | "Two plus two equals five" (2 + 2 = 5) is a mathematically incorrect phrase used in the 1949 dystopian novel Nineteen Eighty-Four by George Orwell. It appears as a possible statement of Ingsoc (English Socialism) philosophy, like the dogma "War is Peace", which the Party expects the citizens of Oceania to believe is true. In writing his secret diary in the year 1984, the protagonist Winston Smith ponders if the Inner Party might declare that "two plus two equals five" is a fact. Smith further ponders whether or not belief in such a consensus reality makes the lie true.
About the falsity of "two plus two equals five", in the Ministry of Love, the interrogator O'Brien tells the thought criminal Smith that control over physical reality is unimportant to the Party, provided the citizens of Oceania subordinate their real-world perceptions to the political will of the Party; and that, by way of doublethink: "Sometimes, Winston. [Sometimes it is four fingers.] Sometimes they are five. Sometimes they are three. Sometimes they are all of them at once".
As a theme and as a subject in the arts, the anti-intellectual slogan 2 + 2 = 5 pre-dates Orwell and has produced literature, such as Deux et deux font cinq (Two and Two Make Five), written in 1895 by Alphonse Allais, which is a collection of absurdist short stories; and the 1920 imagist art manifesto 2 × 2 = 5 by the poet Vadim Shershenevich, in the 20th century.
Self-evident truth and self-evident falsehood
In the 17th century, in the Meditations on First Philosophy, in which the Existence of God and the Immortality of the Soul are Demonstrated (1641), René Descartes said that the standard of truth is self-evidence of clear and distinct ideas. Despite the logician Descartes' understanding of "self-evident truth", the philosopher Descartes considered that the self-evident truth of "two plus two equals four" might not exist beyond the human mind; that there might not exist correspondence between abstract ideas and concret |
https://en.wikipedia.org/wiki/Eric%20Temple%20Bell | Eric Temple Bell (7 February 1883 – 21 December 1960) was a Scottish-born mathematician and science fiction writer who lived in the United States for most of his life. He published non-fiction using his given name and fiction as John Taine.
Early life and education
Eric Temple Bell was born in Peterhead, Aberdeen, Scotland as third of three children to Helen Jane Lyall and James Bell Jr. His father, a factor, relocated to San Jose, California, in 1884, when Eric was fifteen months old. After his father died on 4 January 1896, the family returned to Bedford, England.
Bell was educated at Bedford Modern School, where his teacher Edward Mann Langley inspired him to continue the study of mathematics. Bell returned to the United States, by way of Montreal, in 1902. He received degrees from Stanford University (1904), the University of Washington (1908), and Columbia University (1912) (where he was a student of Cassius Jackson Keyser).
Career
Bell was part of the faculty first at the University of Washington and later at the California Institute of Technology. While at the University of Washington, he taught Howard P. Robertson and encouraged him to enroll at Cal Tech for his doctoral studies.
Bell researched number theory; see in particular Bell series. He attempted—not altogether successfully—to make the traditional umbral calculus (understood at that time to be the same thing as the "symbolic method" of Blissard) logically rigorous. He also did much work using generating functions, treated as formal power series, without concern for convergence. He is the eponym of the Bell polynomials and the Bell numbers of combinatorics.
In 1924 Bell was awarded the Bôcher Memorial Prize for his work in mathematical analysis. In 1927, he was elected to the National Academy of Sciences. He was elected to the American Philosophical Society in 1937. He died in 1960 in Watsonville, California.
Work
Fiction and poetry
During the early 1920s, Bell wrote several long poems. He also |
https://en.wikipedia.org/wiki/Fubini%27s%20theorem | In mathematical analysis, Fubini's theorem is a result that gives conditions under which it is possible to compute a double integral by using an iterated integral, introduced by Guido Fubini in 1907. One may switch the order of integration if the double integral yields a finite answer when the integrand is replaced by its absolute value.
Fubini's theorem implies that two iterated integrals are equal to the corresponding double integral across its integrands. Tonelli's theorem, introduced by Leonida Tonelli in 1909, is similar, but applies to a non-negative measurable function rather than one integrable over their domains.
A related theorem is often called Fubini's theorem for infinite series, which states that if is a doubly-indexed sequence of real numbers, and if is absolutely convergent, then
Although Fubini's theorem for infinite series is a special case of the more general Fubini's theorem, it is not appropriate to characterize it as a logical consequence of Fubini's theorem. This is because some properties of measures, in particular sub-additivity, are often proved using Fubini's theorem for infinite series. In this case, Fubini's general theorem is a logical consequence of Fubini's theorem for infinite series.
History
The special case of Fubini's theorem for continuous functions on a product of closed bounded subsets of real vector spaces was known to Leonhard Euler in the 18th century. extended this to bounded measurable functions on a product of intervals. Levi conjectured that the theorem could be extended to functions that were integrable rather than bounded, and this was proved by . gave a variation of Fubini's theorem that applies to non-negative functions rather than integrable functions.
Product measures
If X and Y are measure spaces with measures, there are several natural ways to define a product measure on their product.
The product X × Y of measure spaces (in the sense of category theory) has as its measurable sets the σ-algebra generat |
https://en.wikipedia.org/wiki/Apple%20SOS | The Sophisticated Operating System, or SOS (), is the primary operating system of the Apple III computer. SOS was developed by Apple Computer and released in October 1980.
In 1985, Steve Wozniak, while critical of the Apple III's hardware flaws, called SOS "the finest operating system on any microcomputer ever".
Technical details
SOS is a single-tasking single-user operating system. It makes the resources of the Apple III available in the form of a menu-driven utility program as well as a programming application programming interface (API). A single program is loaded at boot time, called the interpreter. Once loaded, the interpreter can then use the SOS API to make requests of the system. The SOS API is divided into four main areas:
File Calls: Create, destroy, rename, open, close, read, write files; set, get prefix (current working directory); set, get file information; get volume information; set, set mark, EOF, and level of files
Device Calls: Get status, device number, information of a device; send device control data
Memory Calls: Request, find, change, release memory segment; get segment information; set segment number
Utility Calls: Get, set fence (event threshold); get, set time; get analog (joystick) data; terminate.
The Apple III System Utilities program shipped with each Apple III computer. It provides the user interface of the operating system itself, for system configuration and file management. The System Utilities program is menu-driven and performs tasks in three categories:
Device-handling commands: copy, rename, format, verify volumes (drives); list devices; set time and date
File-handling commands: list, copy, delete, rename files; create subdirectories; set file write protection; set prefix (current working directory)
System Configuration Program (SCP): configure device drivers.
SOS has two types of devices it communicates with via device drivers: character devices and block devices. Examples of SOS character devices are keyboards and seria |
https://en.wikipedia.org/wiki/Honeyguide | Honeyguides (family Indicatoridae) are near passerine birds in the order Piciformes. They are also known as indicator birds, or honey birds, although the latter term is also used more narrowly to refer to species of the genus Prodotiscus. They have an Old World tropical distribution, with the greatest number of species in Africa and two in Asia. These birds are best known for their interaction with humans. Honeyguides are noted and named for one or two species that will deliberately lead humans (but, contrary to popular claims, not honey badgers) directly to bee colonies, so that they can feast on the grubs and beeswax that are left behind.
Description
Most honeyguides are dull-colored, though some have bright yellow coloring in the plumage. All have light outer tail feathers, which are white in all the African species. The smallest species by body mass appears to be the green-backed honeyguide, at an average of , and by length appears to be the Cassin's honeyguide, at an average of , while the largest species by weight is the lyre-tailed honeyguide, at , and by length, is the greater honeyguide, at .
They are among the few birds that feed regularly on wax—beeswax in most species, and presumably the waxy secretions of scale insects in the genus Prodotiscus and to a lesser extent in Melignomon and the smaller species of Indicator. They also feed on waxworms which are the larvae of the waxmoth Galleria mellonella, on bee colonies, and on flying and crawling insects, spiders, and occasional fruits. Many species join mixed-species feeding flocks.
Behavior
Guiding
Honeyguides are named for a remarkable habit seen in one or two species: guiding humans to bee colonies. Once the hive is open and the honey is taken, the bird feeds on larvae and wax. This behavior has been studied in the greater honeyguide; some authorities (following Friedmann, 1955) state that it also occurs in the scaly-throated honeyguide, while others disagree. Wild honeyguides understand various |
https://en.wikipedia.org/wiki/Thermodynamic%20potential | A thermodynamic potential (or more accurately, a thermodynamic potential energy) is a scalar quantity used to represent the thermodynamic state of a system. Just as in mechanics, where potential energy is defined as capacity to do work, similarly different potentials have different meanings. The concept of thermodynamic potentials was introduced by Pierre Duhem in 1886. Josiah Willard Gibbs in his papers used the term fundamental functions.
One main thermodynamic potential that has a physical interpretation is the internal energy . It is the energy of configuration of a given system of conservative forces (that is why it is called potential) and only has meaning with respect to a defined set of references (or data). Expressions for all other thermodynamic energy potentials are derivable via Legendre transforms from an expression for . In other words, each thermodynamic potential is equivalent to other thermodynamic potentials; each potential is a different expression of the others.
In thermodynamics, external forces, such as gravity, are counted as contributing to total energy rather than to thermodynamic potentials. For example, the working fluid in a steam engine sitting on top of Mount Everest has higher total energy due to gravity than it has at the bottom of the Mariana Trench, but the same thermodynamic potentials. This is because the gravitational potential energy belongs to the total energy rather than to thermodynamic potentials such as internal energy.
Description and interpretation
Five common thermodynamic potentials are:
where = temperature, = entropy, = pressure, = volume. is the number of particles of type in the system and is the chemical potential for an -type particle. The set of all are also included as natural variables but may be ignored when no chemical reactions are occurring which cause them to change. The Helmholtz free energy is in ISO/IEC standard called Helmholtz energy or Helmholtz function. It is often denoted by the symb |
https://en.wikipedia.org/wiki/Helmholtz%20free%20energy | In thermodynamics, the Helmholtz free energy (or Helmholtz energy) is a thermodynamic potential that measures the useful work obtainable from a closed thermodynamic system at a constant temperature (isothermal). The change in the Helmholtz energy during a process is equal to the maximum amount of work that the system can perform in a thermodynamic process in which temperature is held constant. At constant temperature, the Helmholtz free energy is minimized at equilibrium.
In contrast, the Gibbs free energy or free enthalpy is most commonly used as a measure of thermodynamic potential (especially in chemistry) when it is convenient for applications that occur at constant pressure. For example, in explosives research Helmholtz free energy is often used, since explosive reactions by their nature induce pressure changes. It is also frequently used to define fundamental equations of state of pure substances.
The concept of free energy was developed by Hermann von Helmholtz, a German physicist, and first presented in 1882 in a lecture called "On the thermodynamics of chemical processes". From the German word Arbeit (work), the International Union of Pure and Applied Chemistry (IUPAC) recommends the symbol A and the name Helmholtz energy. In physics, the symbol F is also used in reference to free energy or Helmholtz function.
Definition
The Helmholtz free energy is defined as
where
F is the Helmholtz free energy (sometimes also called A, particularly in the field of chemistry) (SI: joules, CGS: ergs),
U is the internal energy of the system (SI: joules, CGS: ergs),
T is the absolute temperature (kelvins) of the surroundings, modelled as a heat bath,
S is the entropy of the system (SI: joules per kelvin, CGS: ergs per kelvin).
The Helmholtz energy is the Legendre transformation of the internal energy U, in which temperature replaces entropy as the independent variable.
Formal development
The first law of thermodynamics in a closed system provides
where is the in |
https://en.wikipedia.org/wiki/Excretion | Excretion is a process in which metabolic waste
is eliminated from an organism. In vertebrates this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after leaving the cell. Excretion is an essential process in all forms of life. For example, in mammals, urine is expelled through the urethra, which is part of the excretory system. In unicellular organisms, waste products are discharged directly through the surface of the cell.
During life activities such as cellular respiration, several chemical reactions take place in the body. These are known as metabolism. These chemical reactions produce waste products such as carbon dioxide, water, salts, urea and uric acid. Accumulation of these wastes beyond a level inside the body is harmful to the body. The excretory organs remove these wastes. This process of removal of metabolic waste from the body is known as excretion.
Green plants excrete carbon dioxide and water as respiratory products. In green plants, the carbon dioxide released during respiration gets used during photosynthesis. Oxygen is a by product generated during photosynthesis, and exits through stomata, root cell walls, and other routes. Plants can get rid of excess water by transpiration and guttation. It has been shown that the leaf acts as an 'excretophore' and, in addition to being a primary organ of photosynthesis, is also used as a method of excreting toxic wastes via diffusion. Other waste materials that are exuded by some plants — resin, saps, latex, etc. are forced from the interior of the plant by hydrostatic pressures inside the plant and by absorptive forces of plant cells. These latter processes do not need added energy, they act passively. However, during the pre-abscission phase, the metabolic levels of a leaf are high. Plants also excrete some waste substances into the soil around them.
In animals, the main excretory products are carbon dioxide, ammoni |
https://en.wikipedia.org/wiki/List%20of%20mathematical%20proofs | A list of articles with mathematical proofs:
Theorems of which articles are primarily devoted to proving them
Bertrand's postulate and a proof
Estimation of covariance matrices
Fermat's little theorem and some proofs
Gödel's completeness theorem and its original proof
Mathematical induction and a proof
Proof that 0.999... equals 1
Proof that 22/7 exceeds π
Proof that e is irrational
Proof that π is irrational
Proof that the sum of the reciprocals of the primes diverges
Articles devoted to theorems of which a (sketch of a) proof is given
Banach fixed-point theorem
Banach–Tarski paradox
Basel problem
Bolzano–Weierstrass theorem
Brouwer fixed-point theorem
Buckingham π theorem (proof in progress)
Burnside's lemma
Cantor's theorem
Cantor–Bernstein–Schroeder theorem
Cayley's formula
Cayley's theorem
Clique problem (to do)
Compactness theorem (very compact proof)
Erdős–Ko–Rado theorem
Euler's formula
Euler's four-square identity
Euler's theorem
Five color theorem
Five lemma
Fundamental theorem of arithmetic
Gauss–Markov theorem (brief pointer to proof)
Gödel's incompleteness theorem
Gödel's first incompleteness theorem
Gödel's second incompleteness theorem
Goodstein's theorem
Green's theorem (to do)
Green's theorem when D is a simple region
Heine–Borel theorem
Intermediate value theorem
Itô's lemma
Kőnig's lemma
Kőnig's theorem (set theory)
Kőnig's theorem (graph theory)
Lagrange's theorem (group theory)
Lagrange's theorem (number theory)
Liouville's theorem (complex analysis)
Markov's inequality (proof of a generalization)
Mean value theorem
Multivariate normal distribution (to do)
Holomorphic functions are analytic
Pythagorean theorem
Quadratic equation
Quotient rule
Ramsey's theorem
Rao–Blackwell theorem
Rice's theorem
Rolle's theorem
Splitting lemma
squeeze theorem
Sum rule in differentiation
Sum rule in integration
Sylow theorems
Transcendence of e and π (as corollaries of Lindemann–Weierstrass)
Tychonoff's theorem (to do)
Ultrafilter lemma
Ultraparallel theorem
|
https://en.wikipedia.org/wiki/Quantum%20Link | Quantum Link (or Q-Link) was an American and Canadian online service for the Commodore 64 and 128 personal computers that operated starting November 5, 1985. It was operated by Quantum Computer Services of Vienna, Virginia, which later became America Online.
In October 1989 the service was renamed America Online, and made available to users of PC systems as well. The original Q-link service was terminated November 1, 1995 in favor of the America Online brand.
The original Q-Link was a modified version of the PlayNET system, which Control Video Corporation licensed. Q-Link featured electronic mail, online chat (in its People Connection department), public domain file sharing libraries, online news, and instant messaging using On Line Messages (OLMs). Other noteworthy features included multiplayer games like checkers, chess, backgammon, hangman, and a clone of the television game show "Wheel Of Fortune" called 'Puzzler'; and an interactive graphic resort island, called Habitat during beta-testing, then renamed Club Caribe.
In October 1986, QuantumLink expanded their services to include casino games such as bingo, slot machines, blackjack and poker in RabbitJack's Casino; and RockLink, a section about rock music. The software archives were also organized into hierarchical folders and expanded.
In November 1986, the service began offering to digitize users' photos to be included in their profiles, and started an online auction service.
Connections to Q-Link were typically made by dial-up modems with speeds from 300 to 2400 baud, with 1200 being the most common. The service was normally open weekday evenings and all day on weekends. Pricing was $9.95 per month, with additional fees of six cents per minute (later raised to eight) for so-called "plus" areas, including most of the aforementioned services. Users were given one free hour of "plus" usage per month. Hosts of forums and trivia games could also earn additional free "plus" time.
Q-Link competed with online |
https://en.wikipedia.org/wiki/DNA%20microarray | A DNA microarray (also commonly known as DNA chip or biochip) is a collection of microscopic DNA spots attached to a solid surface. Scientists use DNA microarrays to measure the expression levels of large numbers of genes simultaneously or to genotype multiple regions of a genome. Each DNA spot contains picomoles (10−12 moles) of a specific DNA sequence, known as probes (or reporters or oligos). These can be a short section of a gene or other DNA element that are used to hybridize a cDNA or cRNA (also called anti-sense RNA) sample (called target) under high-stringency conditions. Probe-target hybridization is usually detected and quantified by detection of fluorophore-, silver-, or chemiluminescence-labeled targets to determine relative abundance of nucleic acid sequences in the target. The original nucleic acid arrays were macro arrays approximately 9 cm × 12 cm and the first computerized image based analysis was published in 1981. It was invented by Patrick O. Brown. An example of its application is in SNPs arrays for polymorphisms in cardiovascular diseases, cancer, pathogens and GWAS analysis. It is also used for the identification of structural variations and the measurement of gene expression.
Principle
The core principle behind microarrays is hybridization between two DNA strands, the property of complementary nucleic acid sequences to specifically pair with each other by forming hydrogen bonds between complementary nucleotide base pairs. A high number of complementary base pairs in a nucleotide sequence means tighter non-covalent bonding between the two strands. After washing off non-specific bonding sequences, only strongly paired strands will remain hybridized. Fluorescently labeled target sequences that bind to a probe sequence generate a signal that depends on the hybridization conditions (such as temperature), and washing after hybridization. Total strength of the signal, from a spot (feature), depends upon the amount of target sample binding to the |
https://en.wikipedia.org/wiki/Stairs | Stairs are a structure designed to bridge a large vertical distance between lower and higher levels by dividing it into smaller vertical distances. This is achieved as a diagonal series of horizontal platforms called steps which enable passage to the other level by stepping from one to another step in turn. Steps are very typically rectangular. Stairs may be straight, round, or may consist of two or more straight pieces connected at angles.
Types of stairs include staircases (also called stairways), ladders, and escalators. Some alternatives to stairs are elevators (also called lifts), stairlifts, inclined moving walkways, and ramps. A stairwell is a vertical shaft or opening that contains a staircase. A flight (of stairs) is an inclined part of a staircase consisting of steps (and their lateral supports if supports are separate from steps).
Components and terms
A stair, or a stairstep, is one step in a flight of stairs. In buildings, stairs is a term applied to a complete flight of steps between two floors. A stair flight is a run of stairs or steps between landings. A staircase or stairway is one or more flights of stairs leading from one floor to another, and includes landings, newel posts, handrails, balustrades and additional parts. A stairwell is a compartment extending vertically through a building in which stairs are placed. A stair hall is the stairs, landings, hallways, or other portions of the public hall through which it is necessary to pass when going from the entrance floor to the other floors of a building. Box stairs are stairs built between walls, usually with no support except the wall strings.
Stairs may be in a "straight run", leading from one floor to another without a turn or change in direction. Stairs may change direction, commonly by two straight flights connected at a 90° angle landing. Stairs may also return onto themselves with 180° angle landings at each end of straight flights forming a vertical stairway commonly used in multistory |
https://en.wikipedia.org/wiki/OpenLDAP | OpenLDAP is a free, open-source implementation of the Lightweight Directory Access Protocol (LDAP) developed by the OpenLDAP Project. It is released under its own BSD-style license called the OpenLDAP Public License.
LDAP is a platform-independent protocol. Several common Linux distributions include OpenLDAP Software for LDAP support. The software also runs on BSD-variants, as well as AIX, Android, HP-UX, macOS, OpenVMS, Solaris, Microsoft Windows (NT and derivatives, e.g. 2000, XP, Vista, Windows 7, etc.), and z/OS.
History
The OpenLDAP project was started in 1998 by Kurt Zeilenga. The project started by cloning the LDAP reference source from the University of Michigan where a long-running project had supported development and evolution of the LDAP protocol until that project's final release in 1996.
, the OpenLDAP project has four core team members: Howard Chu (chief architect), Quanah Gibson-Mount, Hallvard Furuseth, and Kurt Zeilenga. There are numerous other important and active contributors including Ondrej Kuznik, Luke Howard, Ryan Tandy, and Gavin Henry. Past core team members include Pierangelo Masarati.
Components
OpenLDAP has four main components:
slapd – stand-alone LDAP daemon and associated modules and tools.
lloadd - stand-alone LDAP load balancing proxy server
libraries implementing the LDAP protocol and ASN.1 Basic Encoding Rules (BER)
client software: ldapsearch, ldapadd, ldapdelete, and others
Additionally, the OpenLDAP Project is home to a number of subprojects:
JLDAP – LDAP class libraries for Java
JDBC-LDAP – Java JDBC – LDAP Bridge driver
ldapc++ – LDAP class libraries for C++
LMDB – memory-mapped database library
Backends
Overall concept
Historically the OpenLDAP server (slapd, the Standalone LDAP Daemon) architecture was split between a frontend that handles network access and protocol processing, and a backend that deals strictly with data storage. This split design was a feature of the original University of Michigan code wr |
https://en.wikipedia.org/wiki/Fluorescent%20tag | In molecular biology and biotechnology, a fluorescent tag, also known as a fluorescent label or fluorescent probe, is a molecule that is attached chemically to aid in the detection of a biomolecule such as a protein, antibody, or amino acid. Generally, fluorescent tagging, or labeling, uses a reactive derivative of a fluorescent molecule known as a fluorophore. The fluorophore selectively binds to a specific region or functional group on the target molecule and can be attached chemically or biologically. Various labeling techniques such as enzymatic labeling, protein labeling, and genetic labeling are widely utilized. Ethidium bromide, fluorescein and green fluorescent protein are common tags. The most commonly labelled molecules are antibodies, proteins, amino acids and peptides which are then used as specific probes for detection of a particular target.
History
The development of methods to detect and identify biomolecules has been motivated by the ability to improve the study of molecular structure and interactions. Before the advent of fluorescent labeling, radioisotopes were used to detect and identify molecular compounds. Since then, safer methods have been developed that involve the use of fluorescent dyes or fluorescent proteins as tags or probes as a means to label and identify biomolecules. Although fluorescent tagging in this regard has only been recently utilized, the discovery of fluorescence has been around for a much longer time.
Sir George Stokes developed the Stokes Law of Fluorescence in 1852 which states that the wavelength of fluorescence emission is greater than that of the exciting radiation. Richard Meyer then termed fluorophore in 1897 to describe a chemical group associated with fluorescence. Since then, Fluorescein was created as a fluorescent dye by Adolph von Baeyer in 1871 and the method of staining was developed and utilized with the development of fluorescence microscopy in 1911.
Ethidium bromide and variants were developed |
https://en.wikipedia.org/wiki/Neutrophil | Neutrophils (also known as neutrocytes, heterophils or polymorphonuclear leukocytes) are a type of white blood cell. More specifically, they form the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. They form an essential part of the innate immune system, with their functions varying in different animals.
They are formed from stem cells in the bone marrow and differentiated into subpopulations of neutrophil-killers and neutrophil-cagers. They are short-lived (between 5 and 135 hours, see ) and highly mobile, as they can enter parts of tissue where other cells/molecules cannot. Neutrophils may be subdivided into segmented neutrophils and banded neutrophils (or bands). They form part of the polymorphonuclear cells family (PMNs) together with basophils and eosinophils.
The name neutrophil derives from staining characteristics on hematoxylin and eosin (H&E) histological or cytological preparations. Whereas basophilic white blood cells stain dark blue and eosinophilic white blood cells stain bright red, neutrophils stain a neutral pink. Normally, neutrophils contain a nucleus divided into 2–5 lobes.
Neutrophils are a type of phagocyte and are normally found in the bloodstream. During the beginning (acute) phase of inflammation, particularly as a result of bacterial infection, environmental exposure, and some cancers, neutrophils are one of the first responders of inflammatory cells to migrate toward the site of inflammation. They migrate through the blood vessels and then through interstitial space, following chemical signals such as interleukin-8 (IL-8), C5a, fMLP, Leukotriene B4, and H2O2 in a process called chemotaxis. They are the predominant cells in pus, accounting for its whitish/yellowish appearance.
Neutrophils are recruited to the site of injury within minutes following trauma and are the hallmark of acute inflammation; however, due to some pathogens being indigestible, they might not be able to resolve certain i |
https://en.wikipedia.org/wiki/Leeuwenhoek%20Medal | The Leeuwenhoek Medal, established in 1875 by the Royal Netherlands Academy of Arts and Sciences (KNAW), in honor of the 17th- and 18th-century microscopist Antoni van Leeuwenhoek, is granted every ten years to the scientist judged to have made the most significant contribution to microbiology during the preceding decade. Starting in 2015, the Royal Dutch Society for Microbiology (KNVM) began awarding the Leeuwenhoek Medal, selecting Jillian Banfield, the first woman to receive the award in 2023.
Recipients
Source: KNVM
1877 Christian Gottfried Ehrenberg, Germany
1885 Ferdinand Cohn, Germany
1895 Louis Pasteur, France
1905 Martinus Beijerinck, Netherlands
1915 Sir David Bruce, United Kingdom
1925 Félix d'Herelle, (at the time) Egypt
1935 Sergei Nikolaevitch Winogradsky, France
1950 Selman Abraham Waksman, United States
1960 André Lwoff, France
1970 Cornelius Bernardus van Niel (Kees van Niel), United States
1981 Roger Yate Stanier, France
1992 Carl Woese, United States
2003 Karl Stetter, Germany
2015 Craig Venter, United States of America
2023 Jillian Banfield, Australia
See also
Royal Society Leeuwenhoek Lecture
List of biology awards
References
Biology awards
Dutch honorary society awards
Dutch science and technology awards
Microbiology
1877 establishments in the Netherlands
Antonie van Leeuwenhoek
Awards established in 1877 |
https://en.wikipedia.org/wiki/IBM%20System/34 | The IBM System/34 was an IBM midrange computer introduced in 1977. It was withdrawn from marketing in February 1985. It was a multi-user, multi-tasking successor to the single-user System/32. It included two processors, one based on the System/32 and the second based on the System/3. Like the System/32 and the System/3, the System/34 was primarily programmed in the RPG II language.
Hardware
The 5340 System Unit contained the processing unit, the disk storage and the diskette drive. It had several access doors on both sides. Inside, were swing-out assemblies where the circuit boards and memory cards were mounted. It weighed and used 220V power. The IBM 5250 series of terminals were the primary interface to the System/34.
Processors
S/34s had two processors, the Control Storage Processor (CSP), and the Main Storage Processor (MSP). The MSP was the workhorse, based on System/3 architecture; it performed the instructions in the computer programs. The CSP was the governor, a different processor with different RISC-like instruction set, based on System/32 architecture; it performed system functions in the background. The CSP also executed the optional Scientific Macroinstructions, which were a set of emulated floating point operations used by the System/34 Fortran compiler and optionally in assembly code. The clock speed of the CPUs inside a System/34 was fixed at 1 MHz for the MSP and 4 MHz for the CSP. Special utility programs were able to make direct calls to the CSP to perform certain functions; these are usually system programs like $CNFIG which was used to configure the computer system.
Memory and storage
The smallest S/34 had 48K of RAM and an 8.6 MB hard drive. The largest configured S/34 could support 256K of RAM and 256MB of disk space. S/34 hard drives contained a feature called "the extra cylinder," so that bad spots on the drive were detected and dynamically mapped out to good spots on the extra cylinder. Disk space on the System/34 was organized by bloc |
https://en.wikipedia.org/wiki/Experimental%20mathematics | Experimental mathematics is an approach to mathematics in which computation is used to investigate mathematical objects and identify properties and patterns. It has been defined as "that branch of mathematics that concerns itself ultimately with the codification and transmission of insights within the mathematical community through the use of experimental (in either the Galilean, Baconian, Aristotelian or Kantian sense) exploration of conjectures and more informal beliefs and a careful analysis of the data acquired in this pursuit."
As expressed by Paul Halmos: "Mathematics is not a deductive science—that's a cliché. When you try to prove a theorem, you don't just list the hypotheses, and then start to reason. What you do is trial and error, experimentation, guesswork. You want to find out what the facts are, and what you do is in that respect similar to what a laboratory technician does."
History
Mathematicians have always practiced experimental mathematics. Existing records of early mathematics, such as Babylonian mathematics, typically consist of lists of numerical examples illustrating algebraic identities. However, modern mathematics, beginning in the 17th century, developed a tradition of publishing results in a final, formal and abstract presentation. The numerical examples that may have led a mathematician to originally formulate a general theorem were not published, and were generally forgotten.
Experimental mathematics as a separate area of study re-emerged in the twentieth century, when the invention of the electronic computer vastly increased the range of feasible calculations, with a speed and precision far greater than anything available to previous generations of mathematicians. A significant milestone and achievement of experimental mathematics was the discovery in 1995 of the Bailey–Borwein–Plouffe formula for the binary digits of π. This formula was discovered not by formal reasoning, but instead
by numerical searches on a computer; only afterwa |
https://en.wikipedia.org/wiki/Mathematical%20problem | A mathematical problem is a problem that can be represented, analyzed, and possibly solved, with the methods of mathematics. This can be a real-world problem, such as computing the orbits of the planets in the solar system, or a problem of a more abstract nature, such as Hilbert's problems. It can also be a problem referring to the nature of mathematics itself, such as Russell's Paradox.
Real-world problems
Informal "real-world" mathematical problems are questions related to a concrete setting, such as "Adam has five apples and gives John three. How many has he left?". Such questions are usually more difficult to solve than regular mathematical exercises like "5 − 3", even if one knows the mathematics required to solve the problem. Known as word problems, they are used in mathematics education to teach students to connect real-world situations to the abstract language of mathematics.
In general, to use mathematics for solving a real-world problem, the first step is to construct a mathematical model of the problem. This involves abstraction from the details of the problem, and the modeller has to be careful not to lose essential aspects in translating the original problem into a mathematical one. After the problem has been solved in the world of mathematics, the solution must be translated back into the context of the original problem.
Abstract problems
Abstract mathematical problems arise in all fields of mathematics. While mathematicians usually study them for their own sake, by doing so, results may be obtained that find application outside the realm of mathematics. Theoretical physics has historically been a rich source of inspiration.
Some abstract problems have been rigorously proved to be unsolvable, such as squaring the circle and trisecting the angle using only the compass and straightedge constructions of classical geometry, and solving the general quintic equation algebraically. Also provably unsolvable are so-called undecidable problems, such as the |
https://en.wikipedia.org/wiki/Ordered%20exponential | The ordered exponential, also called the path-ordered exponential, is a mathematical operation defined in non-commutative algebras, equivalent to the exponential of the integral in the commutative algebras. In practice the ordered exponential is used in matrix and operator algebras.
Definition
Let be an algebra over a real or complex field , and be a parameterized element of ,
The parameter in is often referred to as the time parameter in this context.
The ordered exponential of is denoted
where the term is equal to 1 and where is a higher-order operation that ensures the exponential is time-ordered: any product of that occurs in the expansion of the exponential must be ordered such that the value of is increasing from right to left of the product; a schematic example:
This restriction is necessary as products in the algebra are not necessarily commutative.
The operation maps a parameterized element onto another parameterized element, or symbolically,
There are various ways to define this integral more rigorously.
Product of exponentials
The ordered exponential can be defined as the left product integral of the infinitesimal exponentials, or equivalently, as an ordered product of exponentials in the limit as the number of terms grows to infinity:
where the time moments are defined as for , and .
The ordered exponential is in fact a geometric integral.
Solution to a differential equation
The ordered exponential is unique solution of the initial value problem:
Solution to an integral equation
The ordered exponential is the solution to the integral equation:
This equation is equivalent to the previous initial value problem.
Infinite series expansion
The ordered exponential can be defined as an infinite sum,
This can be derived by recursively substituting the integral equation into itself.
Example
Given a manifold where for a with group transformation it holds at a point :
Here, denotes exterior differentiation and is the |
https://en.wikipedia.org/wiki/Tensor%20field | In mathematics and physics, a tensor field assigns a tensor to each point of a mathematical space (typically a Euclidean space or manifold). Tensor fields are used in differential geometry, algebraic geometry, general relativity, in the analysis of stress and strain in materials, and in numerous applications in the physical sciences. As a tensor is a generalization of a scalar (a pure number representing a value, for example speed) and a vector (a pure number plus a direction, like velocity), a tensor field is a generalization of a scalar field or vector field that assigns, respectively, a scalar or vector to each point of space. If a tensor is defined on a vector fields set over a module , we call a tensor field on .
Many mathematical structures called "tensors" are also tensor fields. For example, the Riemann curvature tensor is a tensor field as it associates a tensor to each point of a Riemannian manifold, which is a topological space.
Definition
Let M be a manifold, for instance the Euclidean plane Rn.
Equivalently, it is a collection of elements Tx ∈ Vx⊗p ⊗ (Vx*)⊗q for all points x ∈ M, arranging into a smooth map T : M → V⊗p ⊗ (V*)⊗q. Elements Tx are called tensors.
Often we take V = TM to be the tangent bundle of M.
Geometric introduction
Intuitively, a vector field is best visualized as an "arrow" attached to each point of a region, with variable length and direction. One example of a vector field on a curved space is a weather map showing horizontal wind velocity at each point of the Earth's surface.
Now consider more complicated fields. For example, if the manifold is Riemannian, then it has a metric field , such that given any two vectors at point , their inner product is . The field could be given in matrix form, but it depends on a choice of coordinates. It could instead be given as an ellipsoid of radius 1 at each point, which is coordinate-free. Applied to the Earth's surface, this is Tissot's indicatrix.
In general, we want to sp |
https://en.wikipedia.org/wiki/Lee%20de%20Forest | Lee de Forest (August 26, 1873 – June 30, 1961) was an American inventor and a fundamentally important early pioneer in electronics. He invented the first practical electronic amplifier,
the three-element "Audion" triode vacuum tube in 1906. This helped start the Electronic Age, and enabled the development of the electronic oscillator. These made radio broadcasting and long distance telephone lines possible, and led to the development of talking motion pictures, among countless other applications.
He had over 300 patents worldwide, but also a tumultuous career — he boasted that he made, then lost, four fortunes. He was also involved in several major patent lawsuits, spent a substantial part of his income on legal bills, and was even tried (and acquitted) for mail fraud.
Despite this, he was recognised for his pioneering work with the 1922 IEEE Medal of Honor, the 1923 Franklin Institute Elliott Cresson Medal and the 1946 American Institute of Electrical Engineers Edison Medal.
Early life
Lee de Forest was born in 1873 in Council Bluffs, Iowa, the son of Anna Margaret ( Robbins) and Henry Swift DeForest. He was a direct descendant of Jessé de Forest, the leader of a group of Walloon Huguenots who fled Europe in the 17th century due to religious persecution.
De Forest's father was a Congregational Church minister who hoped his son would also become a pastor. In 1879 the elder de Forest became president of the American Missionary Association's Talladega College in Talladega, Alabama, a school "open to all of either sex, without regard to sect, race, or color", and which educated primarily African-Americans. Many of the local white citizens resented the school and its mission, and Lee spent most of his youth in Talladega isolated from the white community, with several close friends among the black children of the town.
De Forest prepared for college by attending Mount Hermon Boys' School in Gill, Massachusetts for two years, beginning in 1891. In 1893, he enrolled |
https://en.wikipedia.org/wiki/A.%20K.%20Dewdney | Alexander Keewatin Dewdney (born August 5, 1941) is a Canadian mathematician, computer scientist, author, filmmaker, and conspiracy theorist. Dewdney is the son of Canadian artist and author Selwyn Dewdney, and brother of poet Christopher Dewdney.
He was born in London, Ontario.
Art and fiction
In his student days, Dewdney made a number of influential experimental films, including Malanga, on the poet Gerald Malanga, Four Girls, Scissors, and his most ambitious film, the pre-structural Maltese Cross Movement. Margaret Atwood wrote that a poetry scrapbook by Dewdney, based on the Maltese Cross Movement film, "raises scrapbooking to an art".
The Academy Film Archive has preserved two of Dewdney's films: The Maltese Cross Movement in 2009 and Wildwood Flower in 2011.
He has also written two novels, The Planiverse (about an imaginary two-dimensional world) and Hungry Hollow: The Story of a Natural Place. Dewdney lives in London, Ontario, Canada, where he holds the position of Professor Emeritus at the University of Western Ontario.
Computing, mathematics, and science
Dewdney has written a number of books on mathematics, computing, and bad science. He also founded and edited a magazine on recreational programming called Algorithm between 1989 and 1993.
Dewdney followed Martin Gardner and Douglas Hofstadter in authoring Scientific American magazine's recreational mathematics column, renamed to "Computer Recreations", then "Mathematical Recreations", from 1984 to 1991. He has published more than 10 books on scientific possibilities and puzzles. Dewdney was a co-inventor of programming game Core War.
Since the nineties, Dewdney has worked on biology, both as a field ecologist and as a mathematical biologist, contributing a solution to the problem of determining the underlying dynamics of species abundance in natural communities.
Conspiracy theories
Dewdney is a member of the 9/11 truth movement, and has theorized that the planes used in the September 11 attacks ha |
https://en.wikipedia.org/wiki/Qualcomm | Qualcomm Incorporated () is an American multinational corporation headquartered in San Diego, California, and incorporated in Delaware. It creates semiconductors, software, and services related to wireless technology. It owns patents critical to the 5G, 4G, CDMA2000, TD-SCDMA and WCDMA mobile communications standards.
Qualcomm was established in 1985 by Irwin Jacobs and six other co-founders. Its early research into CDMA wireless cell phone technology was funded by selling a two-way mobile digital satellite communications system known as Omnitracs. After a heated debate in the wireless industry, CDMA was adopted as a 2G standard in North America with Qualcomm's patents incorporated. Afterwards there was a series of legal disputes about pricing for licensing patents required by the standard.
Over the years, Qualcomm has expanded into selling semiconductor products in a predominantly fabless manufacturing model. It also developed semiconductor components or software for vehicles, watches, laptops, wi-fi, smartphones, and other devices.
History
Early history
Qualcomm was created in July 1985 by seven former Linkabit employees led by Irwin Jacobs. Other co-founders included Andrew Viterbi, Franklin Antonio, Adelia Coffman, Andrew Cohen, Klein Gilhousen, and Harvey White. The company was named Qualcomm for "Quality Communications". It started as a contract research and development center largely for government and defense projects.
Qualcomm merged with Omninet in 1988 and raised $3.5 million in funding to produce the Omnitracs satellite communications system for trucking companies. Qualcomm grew from eight employees in 1986 to 620 employees in 1991, due to demand for Omnitracs. By 1989, Qualcomm had $32 million in revenue, 50 percent of which was from an Omnitracs contract with Schneider National. Omnitracs profits helped fund Qualcomm's research and development into code-division multiple access (CDMA) technologies for cell phone networks.
1990–2015
Qualcomm was |
https://en.wikipedia.org/wiki/Knuth%27s%20up-arrow%20notation | In mathematics, Knuth's up-arrow notation is a method of notation for very large integers, introduced by Donald Knuth in 1976.
In his 1947 paper, R. L. Goodstein introduced the specific sequence of operations that are now called hyperoperations. Goodstein also suggested the Greek names tetration, pentation, etc., for the extended operations beyond exponentiation. The sequence starts with a unary operation (the successor function with n = 0), and continues with the binary operations of addition (n = 1), multiplication (n = 2), exponentiation (n = 3), tetration (n = 4), pentation (n = 5), etc.
Various notations have been used to represent hyperoperations. One such notation is .
Knuth's up-arrow notation is another.
For example:
the single arrow represents exponentiation (iterated multiplication)
the double arrow represents tetration (iterated exponentiation)
the triple arrow represents pentation (iterated tetration)
The general definition of the up-arrow notation is as follows (for ):
Here, stands for n arrows, so for example
The square brackets are another notation for hyperoperations.
Introduction
The hyperoperations naturally extend the arithmetical operations of addition and multiplication as follows.
Addition by a natural number is defined as iterated incrementation:
Multiplication by a natural number is defined as iterated addition:
For example,
Exponentiation for a natural power is defined as iterated multiplication, which Knuth denoted by a single up-arrow:
For example,
Tetration is defined as iterated exponentiation, which Knuth denoted by a “double arrow”:
For example,
Expressions are evaluated from right to left, as the operators are defined to be right-associative.
According to this definition,
etc.
This already leads to some fairly large numbers, but the hyperoperator sequence does not stop here.
Pentation, defined as iterated tetration, is represented by the “triple arrow”:
Hexation, defined as iterated pentation, is |
https://en.wikipedia.org/wiki/Dynamic%20mechanical%20analysis | Dynamic mechanical analysis (abbreviated DMA) is a technique used to study and characterize materials. It is most useful for studying the viscoelastic behavior of polymers. A sinusoidal stress is applied and the strain in the material is measured, allowing one to determine the complex modulus. The temperature of the sample or the frequency of the stress are often varied, leading to variations in the complex modulus; this approach can be used to locate the glass transition temperature of the material, as well as to identify transitions corresponding to other molecular motions.
Theory
Viscoelastic properties of materials
Polymers composed of long molecular chains have unique viscoelastic properties, which combine the characteristics of elastic solids and Newtonian fluids. The classical theory of elasticity describes the mechanical properties of elastic solid where stress is proportional to strain in small deformations. Such response of stress is independent of strain rate. The classical theory of hydrodynamics describes the properties of viscous fluid, for which the response of stress is dependent on strain rate. This solidlike and liquidlike behavior of polymers can be modeled mechanically with combinations of springs and dashpots.
Dynamic moduli of polymers
The viscoelastic property of a polymer is studied by dynamic mechanical analysis where a sinusoidal force (stress σ) is applied to a material and the resulting displacement (strain) is measured. For a perfectly elastic solid, the resulting strain and the stress will be perfectly in phase. For a purely viscous fluid, there will be a 90 degree phase lag of strain with respect to stress. Viscoelastic polymers have the characteristics in between where some phase lag will occur during DMA tests. When the strain is applied and the stress lags behind, the following equations hold:
Stress:
Strain:
where
is frequency of strain oscillation,
is time,
is phase lag between stress and strain.
Consider the purely e |
https://en.wikipedia.org/wiki/Thermal%20analysis | Thermal analysis is a branch of materials science where the properties of materials are studied as they change with temperature. Several methods are commonly used – these are distinguished from one another by the property which is measured:
Dielectric thermal analysis: dielectric permittivity and loss factor
Differential thermal analysis: temperature difference versus temperature or time
Differential scanning calorimetry: heat flow changes versus temperature or time
Dilatometry: volume changes with temperature change
Dynamic mechanical analysis: measures storage modulus (stiffness) and loss modulus (damping) versus temperature, time and frequency
Evolved gas analysis: analysis of gases evolved during heating of a material, usually decomposition products
Isothermal titration calorimetry
Isothermal microcalorimetry
Laser flash analysis: thermal diffusivity and thermal conductivity
Thermogravimetric analysis: mass change versus temperature or time
Thermomechanical analysis: dimensional changes versus temperature or time
Thermo-optical analysis: optical properties
Derivatography: A complex method in thermal analysis
Simultaneous thermal analysis generally refers to the simultaneous application of thermogravimetry and differential scanning calorimetry to one and the same sample in a single instrument. The test conditions are perfectly identical for the thermogravimetric analysis and differential scanning calorimetry signals (same atmosphere, gas flow rate, vapor pressure of the sample, heating rate, thermal contact to the sample crucible and sensor, radiation effect, etc.). The information gathered can even be enhanced by coupling the simultaneous thermal analysis instrument to an Evolved Gas Analyzer like Fourier transform infrared spectroscopy or mass spectrometry.
Other, less common, methods measure the sound or light emission from a sample, or the electrical discharge from a dielectric material, or the mechanical relaxation in a stressed specimen. T |
https://en.wikipedia.org/wiki/Balanced%20audio | Balanced audio is a method of interconnecting audio equipment using balanced interfaces. This type of connection is very important in sound recording and production because it allows the use of long cables while reducing susceptibility to external noise caused by electromagnetic interference. The balanced interface guarantees that induced noise appears as common-mode voltages at the receiver which can be rejected by a differential device.
Balanced connections typically use shielded twisted-pair cable and three-conductor connectors. The connectors are usually three-pin XLR or TRS phone connectors. When used in this manner, each cable carries one channel, therefore stereo audio (for example) would require two of them.
A common misconception is that balanced audio requires the signal source to deliver equal waveforms of opposite polarity to the two signal conductors of the balanced line. However, many balanced devices actively drive only one side of the line, but do so at an impedance that is equal to the impedance of the non-driven side of the line. This impedance balance permits the balanced line receiver (input stage of the next device) to reject common-mode signals introduced to the two conductors by electromagnetic coupling.
Applications
Many microphones operate at low voltage levels and some with high output impedance (hi-Z), which makes long microphone cables especially susceptible to electromagnetic interference. Microphone interconnections are therefore a common application for a balanced interconnection, which allows the receiver to reject most of this induced noise. If the power amplifiers of a public address system are located at any distance from the mixing console, it is also normal to use balanced lines for the signal paths from the mixer to these amplifiers. Many other components, such as graphic equalizers and effects units, have balanced inputs and outputs to allow this. In recording and for short cable runs in general, a compromise is necessar |
https://en.wikipedia.org/wiki/Phone%20connector%20%28audio%29 | A phone connector, also known as phone jack, audio jack, headphone jack or jack plug, is a family of electrical connectors typically used for analog audio signals. A plug, the "male" connector, is inserted into the jack, the "female" connector.
The phone connector was invented for use in telephone switchboards in the 19th century and is still widely used.
The phone connector is cylindrical in shape, with a grooved tip to retain it. In its original audio configuration, it typically has two, three, four or, occasionally, five contacts. Three-contact versions are known as TRS connectors (tip, ring, sleeve). Ring contacts are typically the same diameter as the sleeve, the long shank. Similarly, two-, four- and five-contact versions are called TS, TRRS and TRRRS connectors respectively. The outside diameter of the "sleeve" conductor is . The "mini" connector has a diameter of and the "sub-mini" connector has a diameter of . The "mini" connector has a length of .
Other terms
Specific models, and connectors used in specific applications, may be termed e.g. stereo plug, headphone jack, microphone jack, aux input, etc. The 3.5 mm versions are mini-phone, mini-stereo, mini jack, etc.
In the UK, jack plug and jack socket are the male and female phone connectors. In the US, a stationary (more fixed) electrical connector is the jack. The terms phone plug and phone jack sometimes refer to different genders of phone connectors, but also sometimes refer to the RJ11 and older telephone plugs and corresponding jacks that connect wired telephones to wall outlets.
Phone plugs and jacks are different from phono plugs and phono jacks (or in the UK, phono socket) which are RCA connectors common in consumer hi-fi and audiovisual equipment. The 3.5 mm connector is, however, sometimes—but counter to the connector manufacturers' nomenclature—referred to as mini phono.
Historical development
Quarter-inch size
Modern phone connectors are available in three standard sizes. The original |
https://en.wikipedia.org/wiki/Malnutrition | Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is "a deficiency, excess, or imbalance of energy, protein and other nutrients" which adversely affects the body's tissues and form. Malnutrition is not receiving the correct amount of nutrition. Malnutrition is increasing in children under the age of five due to providers who cannot afford or do not have access to adequate nutrition.
Malnutrition is a category of diseases that includes undernutrition and overnutrition. Undernutrition is a lack of nutrients, which can result in stunted growth, wasting, and underweight. A surplus of nutrients causes overnutrition, which can result in obesity. In some developing countries, overnutrition in the form of obesity is beginning to appear within the same communities as undernutrition.
Most clinical studies use the term 'malnutrition' to refer to undernutrition. However, the use of 'malnutrition' instead of 'undernutrition' makes it impossible to distinguish between undernutrition and overnutrition, a less acknowledged form of malnutrition. Accordingly, a 2019 report by The Lancet Commission suggested expanding the definition of malnutrition to include "all its forms, including obesity, undernutrition, and other dietary risks." The World Health Organization and The Lancet Commission have also identified "[t]he double burden of malnutrition," which occurs from "the coexistence of overnutrition (overweight and obesity) alongside undernutrition (stunted growth and wasting)."
Prevalence
It is estimated that nearly one in three persons globally has at least one form of malnutrition: wasting, stunting, vitamin or mineral deficiency, overweight, obesity, or diet-related noncommunicable diseases. Undernutrition is more common in developing countries. Stunting is more prevalent in urban slums than in rural areas. Studies on malnutrition have the population categorised into different groups including infants, under- |
https://en.wikipedia.org/wiki/Ergodic%20hypothesis | In physics and thermodynamics, the ergodic hypothesis says that, over long periods of time, the time spent by a system in some region of the phase space of microstates with the same energy is proportional to the volume of this region, i.e., that all accessible microstates are equiprobable over a long period of time.
Liouville's theorem states that, for a Hamiltonian system, the local density of microstates following a particle path through phase space is constant as viewed by an observer moving with the ensemble (i.e., the convective time derivative is zero). Thus, if the microstates are uniformly distributed in phase space initially, they will remain so at all times. But Liouville's theorem does not imply that the ergodic hypothesis holds for all Hamiltonian systems.
The ergodic hypothesis is often assumed in the statistical analysis of computational physics. The analyst would assume that the average of a process parameter over time and the average over the statistical ensemble are the same. This assumption—that it is as good to simulate a system over a long time as it is to make many independent realizations of the same system—is not always correct. (See, for example, the Fermi–Pasta–Ulam–Tsingou experiment of 1953.)
Assumption of the ergodic hypothesis allows proof that certain types of perpetual motion machines of the second kind are impossible.
Systems that are ergodic are said to have the property of ergodicity; a broad range of systems in geometry, physics, and probability are ergodic. Ergodic systems are studied in ergodic theory.
Phenomenology
In macroscopic systems, the timescales over which a system can truly explore the entirety of its own phase space can be sufficiently large that the thermodynamic equilibrium state exhibits some form of ergodicity breaking. A common example is that of spontaneous magnetisation in ferromagnetic systems, whereby below the Curie temperature the system preferentially adopts a non-zero magnetisation even though the er |
https://en.wikipedia.org/wiki/Ergodic%20theory | Ergodic theory is a branch of mathematics that studies statistical properties of deterministic dynamical systems; it is the study of ergodicity. In this context, "statistical properties" refers to properties which are expressed through the behavior of time averages of various functions along trajectories of dynamical systems. The notion of deterministic dynamical systems assumes that the equations determining the dynamics do not contain any random perturbations, noise, etc. Thus, the statistics with which we are concerned are properties of the dynamics.
Ergodic theory, like probability theory, is based on general notions of measure theory. Its initial development was motivated by problems of statistical physics.
A central concern of ergodic theory is the behavior of a dynamical system when it is allowed to run for a long time. The first result in this direction is the Poincaré recurrence theorem, which claims that almost all points in any subset of the phase space eventually revisit the set. Systems for which the Poincaré recurrence theorem holds are conservative systems; thus all ergodic systems are conservative.
More precise information is provided by various ergodic theorems which assert that, under certain conditions, the time average of a function along the trajectories exists almost everywhere and is related to the space average. Two of the most important theorems are those of Birkhoff (1931) and von Neumann which assert the existence of a time average along each trajectory. For the special class of ergodic systems, this time average is the same for almost all initial points: statistically speaking, the system that evolves for a long time "forgets" its initial state. Stronger properties, such as mixing and equidistribution, have also been extensively studied.
The problem of metric classification of systems is another important part of the abstract ergodic theory. An outstanding role in ergodic theory and its applications to stochastic processes is played |
https://en.wikipedia.org/wiki/Primary%20key | In the relational model of databases, a primary key is a specific choice of a minimal set of attributes (columns) that uniquely specify a tuple (row) in a relation (table). Informally, a primary key is "which attributes identify a record," and in simple cases constitute a single attribute: a unique ID. More formally, a primary key is a choice of candidate key (a minimal superkey); any other candidate key is an alternate key.
A primary key may consist of real-world observables, in which case it is called a natural key, while an attribute created to function as a key and not used for identification outside the database is called a surrogate key. For example, for a database of people (of a given nationality), time and location of birth could be a natural key. National identification number is another example of an attribute that may be used as a natural key.
Design
In relational database terms, a primary key does not differ in form or function from a key that isn't primary. In practice, various motivations may determine the choice of any one key as primary over another. The designation of a primary key may indicate the "preferred" identifier for data in the table, or that the primary key is to be used for foreign key references from other tables or it may indicate some other technical rather than semantic feature of the table. Some languages and software have special syntax features that can be used to identify a primary key as such (e.g. the PRIMARY KEY constraint in SQL).
The relational model, as expressed through relational calculus and relational algebra, does not distinguish between primary keys and other kinds of keys. Primary keys were added to the SQL standard mainly as a convenience to the application programmer.
Primary keys can be an integer that is incremented, a universally unique identifier (UUID) or can be generated using Hi/Lo algorithm.
Defining primary keys in SQL
Primary keys are defined in the ISO SQL Standard, through the PRIMARY KEY constrain |
https://en.wikipedia.org/wiki/Foreign%20key | A foreign key is a set of attributes in a table that refers to the primary key of another table. The foreign key links these two tables. Another way to put it: In the context of relational databases, a foreign key is a set of attributes subject to a certain kind of inclusion dependency constraints, specifically a constraint that the tuples consisting of the foreign key attributes in one relation, R, must also exist in some other (not necessarily distinct) relation, S, and furthermore that those attributes must also be a candidate key in S. In simpler words, a foreign key is a set of attributes that references a candidate key. For example, a table called TEAM may have an attribute, MEMBER_NAME, which is a foreign key referencing a candidate key, PERSON_NAME, in the PERSON table. Since MEMBER_NAME is a foreign key, any value existing as the name of a member in TEAM must also exist as a person's name in the PERSON table; in other words, every member of a TEAM is also a PERSON.
Important points to note:-
The reference relation should already be created.
The referenced attribute must be a part of primary key of the referenced relation.
Data type and size of referenced and referencing attribute must be same.
Summary
The table containing the foreign key is called the child table, and the table containing the candidate key is called the referenced or parent table. In database relational modeling and implementation, a candidate key is a set of zero or more attributes, the values of which are guaranteed to be unique for each tuple (row) in a relation. The value or combination of values of candidate key attributes for any tuple cannot be duplicated for any other tuple in that relation.
Since the purpose of the foreign key is to identify a particular row of referenced table, it is generally required that the foreign key is equal to the candidate key in some row of the primary table, or else have no value (the NULL value.). This rule is called a referential integrity con |
https://en.wikipedia.org/wiki/Quadrics%20%28company%29 | Quadrics was a supercomputer company formed in 1996 as a joint venture between Alenia Spazio and the technical team from Meiko Scientific. They produced hardware and software for clustering commodity computer systems into massively parallel systems. Their highpoint was in June 2003 when six out of the ten fastest supercomputers in the world were based on Quadrics' interconnect. They officially closed on June 29, 2009.
Company history
The Quadrics name was first used in 1993 for a commercialized version of the APE100 SIMD parallel computer produced by Alenia Spazio and originally developed by INFN, the Italian National Institute of Nuclear Physics. In 1996, a new Alenia subsidiary, Quadrics Supercomputers World (QSW) was formed, based in Bristol, UK and Rome, Italy, inheriting the Quadrics SIMD product line and the Meiko CS-2 massively parallel supercomputer architecture. In 2002 the company name was shortened to be simply Quadrics.
Initially, the new company focussed on the development potential of the CS-2's processor interconnect technology. Their first design was the Elan2 network ASIC, intended for use with the UltraSPARC CPU, attached to it using the Ultra Port Architecture (UPA) system bus. Plans to introduce the Elan2 were later dropped, and a new Elan3 hosted on PCI introduced instead. By the time of its release Elan3 had been re-aimed at the Alpha/PCI market instead, after Quadrics had formed a relationship with Digital Equipment Corporation (DEC).
The combination of Quadrics and Alpha 21264 (EV6) microprocessors proved very successful, and Digital/Compaq rapidly became one of the world's largest suppliers of supercomputers. This culminated with the building the largest machine in the US, the 20 TFLOP ASCI Q, installed at Los Alamos National Laboratory during 2002 and 2003. The machine consisted of 2,048 AlphaServer SC nodes (which are based on AlphaServer ES45), each with four 1.25 GHz Alpha 21264A (EV67) microprocessors and two rails of the Quadrics Q |
https://en.wikipedia.org/wiki/Grade%20%28slope%29 | The grade (also called slope, incline, gradient, mainfall, pitch or rise) of a physical feature, landform or constructed line refers to the tangent of the angle of that surface to the horizontal. It is a special case of the slope, where zero indicates horizontality. A larger number indicates higher or steeper degree of "tilt". Often slope is calculated as a ratio of "rise" to "run", or as a fraction ("rise over run") in which run is the horizontal distance (not the distance along the slope) and rise is the vertical distance.
Slopes of existing physical features such as canyons and hillsides, stream and river banks and beds are often described as grades, but typically grades are used for human-made surfaces such as roads, landscape grading, roof pitches, railroads, aqueducts, and pedestrian or bicycle routes. The grade may refer to the longitudinal slope or the perpendicular cross slope.
Nomenclature
There are several ways to express slope:
as an angle of inclination to the horizontal. (This is the angle opposite the "rise" side of a triangle with a right angle between vertical rise and horizontal run.)
as a percentage, the formula for which is which is equivalent to the tangent of the angle of inclination times 100. In Europe and the U.S. percentage "grade" is the most commonly used figure for describing slopes.
as a per mille figure (‰), the formula for which is which could also be expressed as the tangent of the angle of inclination times 1000. This is commonly used in Europe to denote the incline of a railway. It is sometimes written as mm/m instead of the ‰ symbol.
as a ratio of one part rise to so many parts run. For example, a slope that has a rise of 5 feet for every 1000 feet of run would have a slope ratio of 1 in 200. (The word "in" is normally used rather than the mathematical ratio notation of "1:200".) This is generally the method used to describe railway grades in Australia and the UK. It is used for roads in Hong Kong, and was used for roa |
https://en.wikipedia.org/wiki/TRW%20Inc. | TRW Inc., was an American corporation involved in a variety of businesses, mainly aerospace, electronics, automotive, and credit reporting. It was a pioneer in multiple fields including electronic components, integrated circuits, computers, software and systems engineering. TRW built many spacecraft, including Pioneer 1, Pioneer 10, and several space-based observatories. It was #57 on the 1986 Fortune 500 list, and had 122,258 employees. The company was called Thompson Ramo Wooldridge Inc., after the 1958 merger of the Ramo-Wooldridge Corporation and Thompson Products. This was later shortened to TRW.
The company was founded in 1901 and lasted for just over a century until being acquired by Northrop Grumman in 2002. It spawned a variety of corporations, including Pacific Semiconductors, The Aerospace Corporation, Bunker-Ramo and Experian. Its automotive businesses were sold off by Northrop Grumman as TRW Automotive, which is now part of ZF Friedrichshafen. TRW veterans were instrumental in the founding of corporations like SpaceX.
In 1953, the company was recruited to lead the development of the United States' first ICBM. Starting with the initial design by Convair, the multi-corporate team launched Atlas in 1957. It flew its full range in 1958 and was then adapted to fly the Mercury astronauts into orbit. TRW also led development of the Titan missile, which was later adapted to fly the Gemini missions. The company served the U.S. Air Force as systems engineers on all subsequent ICBM development efforts but TRW never produced any missile hardware because of the conflict of interest. In 1960, Congress spurred the formation of the non-profit Aerospace Corporation to provide systems engineering support to the U.S. government but TRW continued to guide the ICBM efforts.
History
TRW originated in 1901 with the Cleveland Cap Screw Company, founded by David Kurtz and four other Cleveland residents. Their initial products were bolts with heads electrically welded to the |
https://en.wikipedia.org/wiki/ZSNES | ZSNES is a free software Super Nintendo Entertainment System emulator written mostly in x86 assembly with official ports for Linux, DOS, Windows, and unofficial ports for Xbox and macOS.
Background
Development of ZSNES began on 3 July 1997 and the first version was released on 14 October 1997, for DOS. Since then, official ports have been made for Windows and Linux. The emulator became free software under the GPL-2.0-or-later license on 2 April 2001. Despite an announcement by adventure_of_link stating that "ZSNES is NOT dead, it's still in development" made on the ZSNES board after the departure of its original developers zsKnight and _Demo_, development has slowed dramatically since its last version (1.51 released on 24 January 2007). Much of the development efforts concentrated on increasing the emulator's portability, by rewriting assembly code in C and C++, including a new GUI using Qt.
ZSNES is notable in that it was early in being able to emulate several of the SNES enhancement chips at some level. Until version 1.50, ZSNES featured netplay via TCP/IP or UDP.
An early ZSNES feature of interest were "ZMV movies". This feature enabled players to record their play session inputs and then output those to a ZMV file, in such a way that another user with a copy of ZSNES, a matching ROM file, and the ZMV file, should be able to "watch" the other person's gameplay. This long preceded mass availability of gameplay videos online, being an early form of sharing this type of content.
Because ZSNES is largely written in low-level assembly language for x86 processors, the idea of porting ZSNES to devices using RISC architectures such as ARM is highly unfeasible. Commercial gaming consoles did not typically use x86 processors (with the original Xbox being the most well-known exception) prior to the eighth generation, with the 2013 releases of the Xbox One and PlayStation 4.
Development history
The first public release of ZSNES was version 0.150, on October 14, 1997. |
https://en.wikipedia.org/wiki/Nicolas%20Chuquet | Nicolas Chuquet (; born ; died ) was a French mathematician. He invented his own notation for algebraic concepts and exponentiation. He may have been the first mathematician to recognize zero and negative numbers as exponents.
In 1475, Jehan Adam recorded the words "bymillion" and "trimillion" (for 1012 and 1018) and it is believed that these words or similar ones were in general use at that time.
In 1484, Chuquet wrote an article Triparty en la science des nombres, which was unpublished in his lifetime. Most of it, however, was copied without attribution by Estienne de La Roche in his 1520 textbook, l'Arismetique. In the 1870s, scholar Aristide Marre discovered Chuquet's manuscript and published it in 1880. The manuscript contained notes in de la Roche's handwriting. His article shows a huge number divided into groups of six digits, and in a short passage he states that the groups can be called:
"million, the second mark byllion, the third mark tryllion, the fourth quadrillion, the fifth quyillion, the sixth sixlion, the seventh septyllion, the eighth ottyllion, the ninth nonyllion and so on with others as far as you wish to go.
In a second passage, he wrote:
... Item lon doit savoir que ung million vault mille milliers de unitez, et ung byllion vault mille milliers de millions, et [ung] tryllion vault mille milliers de byllions, et ung quadrillion vault mille milliers de tryllions et ainsi des aultres : Et de ce en est pose ung exemple nombre divise et punctoye ainsi que devant est dit, tout lequel nombre monte 745324 tryllions 804300 byllions 700023 millions 654321. Exemple : 745324'8043000'700023'654321 ...
Item: one should know that a million is worth a thousand thousand units, and a byllion is worth a thousand thousand millions, and tryillion is worth a thousand thousand byllions, and a quadrillion is worth a thousand thousand tryllions, and so on for the others. And an example of this follows, a number divided up and punctuated as previously described, t |
https://en.wikipedia.org/wiki/Traffic%20sign | Traffic signs or road signs are signs erected at the side of or above roads to give instructions or provide information to road users. The earliest signs were simple wooden or stone milestones. Later, signs with directional arms were introduced, for example the fingerposts in the United Kingdom and their wooden counterparts in Saxony.
With traffic volumes increasing since the 1930s, many countries have adopted pictorial signs or otherwise simplified and standardized their signs to overcome language barriers, and enhance traffic safety. Such pictorial signs use symbols (often silhouettes) in place of words and are usually based on international protocols. Such signs were first developed in Europe, and have been adopted by most countries to varying degrees.
International conventions
International conventions such as Vienna Convention on Road Signs and Signals have helped to achieve a degree of uniformity in traffic signing in various countries. Countries have also unilaterally (to some extent) followed other countries in order to avoid confusion.
Categories
Traffic signs can be grouped into several types. For example, Annexe 1 of the Vienna Convention on Road Signs and Signals (1968), which on 30 June 2004 had 52 signatory countries, defines eight categories of signs:
A. Danger warning signs
B. Priority signs
C. Prohibitory or restrictive signs
D. Mandatory signs
E. Special regulation signs
F. Information, facilities, or service signs
G. Direction, position, or indication signs
H. Additional panels
In the United States, Canada, Ireland, Australia, and New Zealand signs are categorized as follows:
Regulatory signs
Warning signs
Guide signs
Street name signs
Route marker signs
Expressway signs
Freeway signs
Welcome signs
Informational signs
Recreation and cultural interest signs
Emergency management (civil defense) signs
Temporary traffic control (construction or work zone) signs
School signs
Railroad and light rail signs
Bicycle signs
In t |
https://en.wikipedia.org/wiki/XML%20pipeline | In software, an XML pipeline is formed when XML (Extensible Markup Language) processes, especially XML transformations and XML validations, are connected.
For instance, given two transformations T1 and T2, the two can be connected so that an input XML document is transformed by T1 and then the output of T1 is fed as input document to T2. Simple pipelines like the one described above are called linear; a single input document always goes through the same sequence of transformations to produce a single output document.
Linear operations
Linear operations can be divided in at least two parts
Micro-operations
They operate at the inner document level
Rename - renames elements or attributes without modifying the content
Replace - replaces elements or attributes
Insert - adds a new data element to the output stream at a specified point
Delete - removes an element or attribute (also known as pruning the input tree)
Wrap - wraps elements with additional elements
Reorder - changes the order of elements
Document operations
They take the input document as a whole
Identity transform - makes a verbatim copy of its input to the output
Compare - it takes two documents and compare them
Transform - execute a transform on the input file using a specified XSLT file. Version 1.0 or 2.0 should be specified.
Split - take a single XML document and split it into distinct documents
Sequence operations
They are mainly introduced in XProc and help to handle the sequence of document as a whole
Count - it takes a sequence of documents and counts them
Identity transform - makes a verbatim copy of its input sequence of documents to the output
split-sequence - takes a sequence of documents as input and routes them to different outputs depending on matching rules
wrap-sequence - takes a sequence of documents as input and wraps them into one or more documents
Non-linear
Non-linear operations on pipelines may include:
Conditionals — where a given transformation is executed |
https://en.wikipedia.org/wiki/Initialized%20fractional%20calculus | In mathematical analysis, initialization of the differintegrals is a topic in fractional calculus.
Composition rule of differintegral
A certain counterintuitive property of the differintegral operator should be pointed out, namely the composition law. Although
wherein D−q is the left inverse of Dq, the converse is not necessarily true:
Example
It is instructive to consider elementary integer-order calculus to see what's happening. First, integrate then differentiate, using the example function 3x2 + 1:
on exchanging the order of composition:
in which the constant of integration is c. Even if it wasn't obvious, the initialization terms ƒ'(0) = c, ƒ''(0) = d, etc. could be used. If we neglected those initialization terms, the last equation would show the composition of integration then differentiation (and vice versa) would not hold.
Description of initialization
This is the problem that with the differintegral. If the differintegral is initialized properly, then the hoped-for composition law holds. The problem is that in differentiation, we lose information, as we lost the c in the first equation.
In fractional calculus, however, since the operator has been fractionalized and is thus continuous, an entire complementary function is needed, not just a constant or set of constants. We call this complementary function .
Working with a properly initialized differintegral is the subject of initialized fractional calculus.
See also
Initial conditions
Dynamical systems
References
(technical report).
Fractional calculus |
https://en.wikipedia.org/wiki/Rete%20mirabile | A rete mirabile (Latin for "wonderful net"; plural retia mirabilia) is a complex of arteries and veins lying very close to each other, found in some vertebrates, mainly warm-blooded ones. The rete mirabile utilizes countercurrent blood flow within the net (blood flowing in opposite directions) to act as a countercurrent exchanger. It exchanges heat, ions, or gases between vessel walls so that the two bloodstreams within the rete maintain a gradient with respect to temperature, or concentration of gases or solutes. This term was coined by Galen.
Effectiveness
The effectiveness of retia is primarily determined by how readily the heat, ions, or gases can be exchanged. For a given length, they are most effective with respect to gases or heat, then small ions, and decreasingly so with respect to other substances.
The retia can provide for extremely efficient exchanges. In bluefin tuna, for example, nearly all of the metabolic heat in the venous blood is transferred to the arterial blood, thus conserving muscle temperature; that heat exchange approaches 99% efficiency.
Birds
In birds with webbed feet, retia mirabilia in the legs and feet transfer heat from the outgoing (hot) blood in the arteries to the incoming (cold) blood in the veins. The effect of this biological heat exchanger is that the internal temperature of the feet is much closer to the ambient temperature, thus reducing heat loss. Penguins also have them in the flippers and nasal passages.
Seabirds distill seawater using countercurrent exchange in a so-called salt gland with a rete mirabile. The gland secretes highly concentrated brine stored near the nostrils above the beak. The bird then "sneezes" the brine out. As freshwater is not usually available in their environments, some seabirds, such as pelicans, petrels, albatrosses, gulls and terns, possess this gland, which allows them to drink the salty water from their environments while they are hundreds of miles away from land.
Fish
Fish have evolv |
https://en.wikipedia.org/wiki/Quipu | Quipu (also spelled khipu) are recording devices fashioned from strings historically used by a number of cultures in the region of Andean South America.
A quipu usually consisted of cotton or camelid fiber strings. The Inca people used them for collecting data and keeping records, monitoring tax obligations, collecting census records, calendrical information, and for military organization. The cords stored numeric and other values encoded as knots, often in a base ten positional system. A quipu could have only a few or thousands of cords. The configuration of the quipus has been "compared to string mops." Archaeological evidence has also shown the use of finely carved wood as a supplemental, and perhaps sturdier, base to which the color-coded cords would be attached. A relatively small number have survived.
Objects that can be identified unambiguously as quipus first appear in the archaeological record in the first millennium AD (though debated quipus are much earlier). They subsequently played a key part in the administration of the Kingdom of Cusco and later the Inca Empire, flourishing across the Andes from c. 1100 to 1532 AD. As the region was subsumed under the Spanish Empire, quipus were mostly replaced by European writing and numeral systems, and most quipu were identified as idolatrous and destroyed, but some Spaniards promoted the adaptation of the quipu recording system to the needs of the colonial administration, and some priests advocated the use of quipus for ecclesiastical purposes. In several modern villages, quipus have continued to be important items for the local community. It is unclear how many intact quipus still exist and where, as many have been stored away in mausoleums.
Knotted strings unrelated to quipu have been used to record information by the ancient Chinese, Tibetans and Japanese.
Quipu is the Spanish spelling and the most common spelling in English. Khipu (pronounced , plural: khipukuna) is the word for "knot" in Cusco Quechua. I |
https://en.wikipedia.org/wiki/IBM%20System/36 | The IBM System/36 (often abbreviated as S/36) was a midrange computer marketed by IBM from 1983 to 2000 - a multi-user, multi-tasking successor to the System/34.
Like the System/34 and the older System/32, the System/36 was primarily programmed in the RPG II language. One of the machine's optional features was an off-line storage mechanism (on the 5360 model) that utilized "magazines" – boxes of 8-inch floppies that the machine could load and eject in a nonsequential fashion. The System/36 also had many mainframe features such as programmable job queues and scheduling priority levels.
While these systems were similar to other manufacturer's minicomputers, IBM themselves described the System/32, System/34 and System/36 as "small systems" and later as midrange computers along with the System/38 and succeeding IBM AS/400 range.
The AS/400 series and IBM Power Systems running IBM i can run System/36 code in the System/36 Environment, although the code needs to be recompiled on IBM i first.
Overview of the IBM System/36
The IBM System/36 was a popular small business computer system, first announced on 16 May 1983 and shipped later that year. It had a 17-year product lifespan. The first model of the System/36 was the 5360.
In the 1970s, the US Department of Justice brought an antitrust lawsuit against IBM, claiming it was using unlawful practices to knock out competitors. At this time, IBM had been about to consolidate its entire line (System/370, 4300, System/32, System/34, System/38) into one "family" of computers with the same ISAM database technology, programming languages, and hardware architecture. After the lawsuit was filed, IBM decided it would have two families: the System/38 line, intended for large companies and representing IBM's future direction, and the System/36 line, intended for small companies who had used the company's legacy System/32/34 computers. In the late 1980s the lawsuit was dropped, and IBM decided to recombine the two product lines, cre |
https://en.wikipedia.org/wiki/Polymorphism%20%28computer%20science%29 | In programming language theory and type theory, polymorphism is the provision of a single interface to entities of different types or the use of a single symbol to represent multiple different types. The concept is borrowed from a principle in biology where an organism or species can have many different forms or stages.
The most commonly recognized major forms of polymorphism are:
Ad hoc polymorphism: defines a common interface for an arbitrary set of individually specified types.
Parametric polymorphism: not specifying concrete types and instead use abstract symbols that can substitute for any type.
Subtyping (also called subtype polymorphism or inclusion polymorphism): when a name denotes instances of many different classes related by some common superclass.
History
Interest in polymorphic type systems developed significantly in the 1990s, with practical implementations beginning to appear by the end of the decade. Ad hoc polymorphism and parametric polymorphism were originally described in Christopher Strachey's Fundamental Concepts in Programming Languages, where they are listed as "the two main classes" of polymorphism. Ad hoc polymorphism was a feature of Algol 68, while parametric polymorphism was the core feature of ML's type system.
In a 1985 paper, Peter Wegner and Luca Cardelli introduced the term inclusion polymorphism to model subtypes and inheritance, citing Simula as the first programming language to implement it.
Forms
Ad hoc polymorphism
Christopher Strachey chose the term ad hoc polymorphism to refer to polymorphic functions that can be applied to arguments of different types, but that behave differently depending on the type of the argument to which they are applied (also known as function overloading or operator overloading). The term "ad hoc" in this context is not intended to be pejorative; it refers simply to the fact that this form of polymorphism is not a fundamental feature of the type system. In the Pascal / Delphi example below |
https://en.wikipedia.org/wiki/Fracture | Fracture is the appearance of a crack or complete separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displacement develops perpendicular to the surface, it is called a normal tensile crack or simply a crack; if a displacement develops tangentially, it is called a shear crack, slip band or dislocation.
Brittle fractures occur without any apparent deformation before fracture. Ductile fractures occur after visible deformation. Fracture strength, or breaking strength, is the stress when a specimen fails or fractures. The detailed understanding of how a fracture occurs and develops in materials is the object of fracture mechanics.
Strength
Fracture strength, also known as breaking strength, is the stress at which a specimen fails via fracture. This is usually determined for a given specimen by a tensile test, which charts the stress–strain curve (see image). The final recorded point is the fracture strength.
Ductile materials have a fracture strength lower than the ultimate tensile strength (UTS), whereas in brittle materials the fracture strength is equivalent to the UTS. If a ductile material reaches its ultimate tensile strength in a load-controlled situation, it will continue to deform, with no additional load application, until it ruptures. However, if the loading is displacement-controlled, the deformation of the material may relieve the load, preventing rupture.
The statistics of fracture in random materials have very intriguing behavior, and was noted by the architects and engineers quite early. Indeed, fracture or breakdown studies might be the oldest physical science studies, which still remain intriguing and very much alive. Leonardo da Vinci, more than 500 years ago, observed that the tensile strengths of nominally identical specimens of iron wire decrease with increasing length of the w |
https://en.wikipedia.org/wiki/Kanban | Kanban (Japanese: カンバン and Chinese: 看板, meaning signboard or billboard) is a scheduling system for lean manufacturing (also called just-in-time manufacturing, abbreviated JIT). Taiichi Ohno, an industrial engineer at Toyota, developed kanban to improve manufacturing efficiency. The system takes its name from the cards that track production within a factory. Kanban is also known as the Toyota nameplate system in the automotive industry.
In kanban, problem areas are highlighted by measuring lead time and cycle time of the full process and process steps. One of the main benefits of kanban is to establish an upper limit to work in process (commonly referred as "WIP") inventory to avoid overcapacity. Other systems with similar effect exist, for example CONWIP. A systematic study of various configurations of kanban systems, such as generalized kanban or production authorization card (PAC) and extended kanban, of which CONWIP is an important special case, can be found in Tayur (1993), and more recently Liberopoulos and Dallery (2000), among other papers.
A goal of the kanban system is to limit the buildup of excess inventory at any point in production. Limits on the number of items waiting at supply points are established and then reduced as inefficiencies are identified and removed. Whenever a limit is exceeded, this points to an inefficiency that should be addressed.
Origins
The system originates from the simplest visual stock replenishment signaling system, an empty box. This was first developed in the UK factories producing Spitfires during the Second World War, and was known as the "two bin system." In the late 1940s, Toyota started studying supermarkets with the idea of applying shelf-stocking techniques to the factory floor. In a supermarket, customers generally retrieve what they need at the required time—no more, no less. Furthermore, the supermarket stocks only what it expects to sell in a given time, and customers take only what they need, because future sup |
https://en.wikipedia.org/wiki/Sporgery | Sporgery is the disruptive act of posting a flood of articles to a Usenet newsgroup, with the article headers falsified so that they appear to have been posted by others. The word is a portmanteau of spam and forgery, coined by German software developer, and critic of Scientology, Tilman Hausherr.
Sporgery resembles crapflooding, which is also intended to disrupt a forum. However, sporgery is not merely disruptive but also deceptive or libellous—it involves falsifying objectionable posts so they appear to come from newsgroup regulars. The purpose is not merely to jam the forum, but also to sully the reputations of its regular users by falsely signing their names to offensive posts.
Origins in alt.religion.scientology
The word sporgery was coined in the newsgroup alt.religion.scientology, an Internet newsgroup where people discuss the controversial belief system of Scientology. One of the various actions of the "war" between Scientology and the Internet involved various individuals who had posted more than a million forged newsgroup articles to the newsgroup, using the message headers (valid names and e-mail addresses) of articles written by Scientology critics and other legitimate posters, and appending to those headers the bodies of other articles harvested from racist newsgroups. The result was to flood the newsgroup with over one million forged articles that made the other posters appear to be hateful "racist bigots". (Critics accused Scientology of planning and conducting the spam flood, but the organization denied this.)
The apparent intent of this attack was to render the newsgroup useless for discussion and criticism of Scientology. Another purpose may have been to lower the reputation of the posters so that people would not take their criticisms of Scientology seriously.
At the peak of this attack, the attackers had six computers posting sporgeries into the newsgroup, dumping into USENET an average of 170 megabytes in 44,075 articles every month. From |
https://en.wikipedia.org/wiki/Superplasticity | In materials science, superplasticity is a state in which solid crystalline material is deformed well beyond its usual breaking point, usually over about 400% during tensile deformation. Such a state is usually achieved at high homologous temperature. Examples of superplastic materials are some fine-grained metals and ceramics. Other non-crystalline materials (amorphous) such as silica glass ("molten glass") and polymers also deform similarly, but are not called superplastic, because they are not crystalline; rather, their deformation is often described as Newtonian fluid. Superplastically deformed material gets thinner in a very uniform manner, rather than forming a "neck" (a local narrowing) that leads to fracture. Also, the formation of microvoids, which is another cause of early fracture, is inhibited.
Superplasticity must not be confused with superelasticity.
Historical developments of superplasticity
Some evidence of superplastic-like flow in metals has been found in some artifacts, such as in Wootz steels in ancient India, even though superplasticity was first scientific recognition in the twentieth century in the report on 163% elongation in brass by Bengough in 1912. Later, Jenkins' higher elongation of 300% in Cd–Zn and Pb–Sn alloys in 1928. However, those works did not go further to set a new phenomenon of mechanical properties of materials. Until the work of Pearson was published in 1934, a significant elongation of 1950% was found in Pb–Sn eutectic alloy. It was easy to become the most extensive elongation report in scientific investigation at this time. There was no further interest in superplasticity in the Western World for more than 25 years after Pearson’s effort. Later, Bochvar and Sviderskaya continued superplasticity in the Soviet Union with many publications on Zn–Al alloys. A research institute focused on superplasticity, the Institute of Metals Superplasticity Problems, was established in 1985 in Ufa City, Russia. This institute has remain |
https://en.wikipedia.org/wiki/Cycle%20space | In graph theory, a branch of mathematics, the (binary) cycle space of an undirected graph is the set of its even-degree subgraphs.
This set of subgraphs can be described algebraically as a vector space over the two-element finite field. The dimension of this space is the circuit rank of the graph. The same space can also be described in terms from algebraic topology as the first homology group of the graph. Using homology theory, the binary cycle space may be generalized to cycle spaces over arbitrary rings.
Definitions
The cycle space of a graph can be described with increasing levels of mathematical sophistication as a set of subgraphs, as a binary vector space, or as a homology group.
Graph theory
A spanning subgraph of a given graph G may be defined from any subset S of the edges of G. The subgraph has the same set of vertices as G itself (this is the meaning of the word "spanning") but has the elements of S as its edges. Thus, a graph G with m edges has 2m spanning subgraphs, including G itself as well as the empty graph on the same set of vertices as G. The collection of all spanning subgraphs of a graph G forms the edge space of G.
A graph G, or one of its subgraphs, is said to be Eulerian if each of its vertices has an even number of incident edges (this number is called the degree of the vertex). This property is named after Leonhard Euler who proved in 1736, in his work on the Seven Bridges of Königsberg, that a connected graph has a tour that visits each edge exactly once if and only if it is Eulerian. However, for the purposes of defining cycle spaces, an Eulerian subgraph does not need to be connected; for instance, the empty graph, in which all vertices are disconnected from each other, is Eulerian in this sense. The cycle space of a graph is the collection of its Eulerian spanning subgraphs.
Algebra
If one applies any set operation such as union or intersection of sets to two spanning subgraphs of a given graph, the result will again be a subgra |
https://en.wikipedia.org/wiki/IEEE%20802.6 | IEEE 802.6 is a standard governed by the ANSI for Metropolitan Area Networks (MAN). It is an improvement of an older standard (also created by ANSI) which used the Fiber distributed data interface (FDDI) network structure. The FDDI-based standard failed due to its expensive implementation and lack of compatibility with current LAN standards. The IEEE 802.6 standard uses the Distributed Queue Dual Bus (DQDB) network form. This form supports 150 Mbit/s transfer rates. It consists of two unconnected unidirectional buses. DQDB is rated for a maximum of 160 km before significant signal degradation over fiberoptic cable with an optical wavelength of 1310 nm.
This standard has also failed, mostly for the same reasons that the FDDI standard failed. MANs are traditionally designed using Synchronous Optical Network (SONET), Synchronous Digital Hierarchy (SDH) or Asynchronous Transfer Mode (ATM). Recent designs use native Ethernet or MPLS.
References
IEEE 802.06
Networking standards
Metropolitan area networks |
https://en.wikipedia.org/wiki/Symmetric%20difference | In mathematics, the symmetric difference of two sets, also known as the disjunctive union and set sum, is the set of elements which are in either of the sets, but not in their intersection. For example, the symmetric difference of the sets and is .
The symmetric difference of the sets A and B is commonly denoted by (traditionally, ), , or .
It can be viewed as a form of addition modulo 2.
The power set of any set becomes an abelian group under the operation of symmetric difference, with the empty set as the neutral element of the group and every element in this group being its own inverse. The power set of any set becomes a Boolean ring, with symmetric difference as the addition of the ring and intersection as the multiplication of the ring.
Properties
The symmetric difference is equivalent to the union of both relative complements, that is:
The symmetric difference can also be expressed using the XOR operation ⊕ on the predicates describing the two sets in set-builder notation:
The same fact can be stated as the indicator function (denoted here by ) of the symmetric difference, being the XOR (or addition mod 2) of the indicator functions of its two arguments: or using the Iverson bracket notation .
The symmetric difference can also be expressed as the union of the two sets, minus their intersection:
In particular, ; the equality in this non-strict inclusion occurs if and only if and are disjoint sets. Furthermore, denoting and , then and are always disjoint, so and partition . Consequently, assuming intersection and symmetric difference as primitive operations, the union of two sets can be well defined in terms of symmetric difference by the right-hand side of the equality
.
The symmetric difference is commutative and associative:
The empty set is neutral, and every set is its own inverse:
Thus, the power set of any set X becomes an abelian group under the symmetric difference operation. (More generally, any field of sets forms a group with |
https://en.wikipedia.org/wiki/Translation%20%28biology%29 | In biology, translation is the process in living cells in which proteins are produced using RNA molecules as templates. The generated protein is a sequence of amino acids. This sequence is determined by the sequence of nucleotides in the RNA. The nucleotides are considered three at a time. Each such triple results in addition of one specific amino acid to the protein being generated. The matching from nucleotide triple to amino acid is called the genetic code. The translation is performed by a large complex of functional RNA and proteins called ribosomes. The entire process is called gene expression.
In translation, messenger RNA (mRNA) is decoded in a ribosome, outside the nucleus, to produce a specific amino acid chain, or polypeptide. The polypeptide later folds into an active protein and performs its functions in the cell. The ribosome facilitates decoding by inducing the binding of complementary tRNA anticodon sequences to mRNA codons. The tRNAs carry specific amino acids that are chained together into a polypeptide as the mRNA passes through and is "read" by the ribosome.
Translation proceeds in three phases:
Initiation: The ribosome assembles around the target mRNA. The first tRNA is attached at the start codon.
Elongation: The last tRNA validated by the small ribosomal subunit (accommodation) transfers the amino acid. It carries to the large ribosomal subunit which binds it to the one of the preceding admitted tRNA (transpeptidation). The ribosome then moves to the next mRNA codon to continue the process (translocation), creating an amino acid chain.
Termination: When a stop codon is reached, the ribosome releases the polypeptide. The ribosomal complex remains intact and moves on to the next mRNA to be translated.
In prokaryotes (bacteria and archaea), translation occurs in the cytosol, where the large and small subunits of the ribosome bind to the mRNA. In eukaryotes, translation occurs in the cytoplasm or across the membrane of the endoplasmic ret |
https://en.wikipedia.org/wiki/Sapper | A sapper, also called a combat engineer, is a combatant or soldier who performs a variety of military engineering duties, such as breaching fortifications, demolitions, bridge-building, laying or clearing minefields, preparing field defenses, and road and airfield construction and repair. They are also trained and equipped to serve as provisional infantry, fighting as such as a secondary mission. A sapper's duties facilitate and support movement, defense, and survival of allied forces and impede those of enemies. The term "sapper" is used in the British Army and Commonwealth nations and the U.S. military.
Historical origin
Sapper
A sapper, in the sense first used by the French military, was one who dug trenches to allow besieging forces to advance towards the enemy defensive works and forts over ground that is under the defenders' musket or artillery fire. It comes from the French word sapeur, itself being derived from the verb saper (to undermine, to dig under a wall or building to cause its collapse). This digging was referred to as sapping the enemy fortifications. Saps were excavated by brigades of trained sappers or instructed troops. When an army was defending a fortress with cannons, they had an obvious height and therefore range advantage over the attacker's guns. The attacking army's artillery had to be brought forward, under fire, so as to facilitate effective counter-battery fire.
This was achieved by digging what the French termed a sappe (derived from the archaic French word for spade or entrenching tool). Using techniques developed and perfected by Vauban, the sappers began the trench at such an angle so as to avoid enemy fire enfilading the sappe by firing down its length. As they pressed forward, a position was prepared from which a cannon could suppress the defenders on the fort's bastions. The sappers would then change the course of their trench, zig-zagging toward the fortress wall. Each leg brought the attacker's artillery closer until the |
https://en.wikipedia.org/wiki/Factor%20of%20safety | In engineering, a factor of safety (FoS), also known as (and used interchangeably with) safety factor (SF), expresses how much stronger a system is than it needs to be for an intended load. Safety factors are often calculated using detailed analysis because comprehensive testing is impractical on many projects, such as bridges and buildings, but the structure's ability to carry a load must be determined to a reasonable accuracy.
Many systems are intentionally built much stronger than needed for normal usage to allow for emergency situations, unexpected loads, misuse, or degradation (reliability).
Definition
There are two definitions for the factor of safety (FoS):
The ratio of a structure's absolute strength (structural capability) to actual applied load; this is a measure of the reliability of a particular design. This is a calculated value, and is sometimes referred to, for the sake of clarity, as a realized factor of safety.
A constant required value, imposed by law, standard, specification, contract or custom, to which a structure must conform or exceed. This can be referred to as a design factor, design factor of safety or required factor of safety.
The realized factor of safety must be greater than the required design factor of safety. However, between various industries and engineering groups usage is inconsistent and confusing; there are several definitions used. The cause of much confusion is that various reference books and standards agencies use the factor of safety definitions and terms differently. Building codes, structural and mechanical engineering textbooks often refer to the "factor of safety" as the fraction of total structural capability over what is needed. Those are realized factors of safety (first use). Many undergraduate strength of materials books use "Factor of Safety" as a constant value intended as a minimum target for design (second use).
Calculation
There are several ways to compare the factor of safety for structures. All the |
https://en.wikipedia.org/wiki/Open%20Grid%20Services%20Architecture | Open Grid Services Architecture (OGSA) describes a service-oriented architecture for a grid computing environment for business and scientific use.
It was developed within the Open Grid Forum, which was called the Global Grid Forum (GGF) at the time, around 2002 to 2006.
Description
OGSA is a distributed interaction and computing architecture based around services, assuring interoperability on heterogeneous systems so that different types of resources can communicate and share information. OGSA is based on several other Web service technologies, such as the Web Services Description Language (WSDL) and the Simple Object Access Protocol (SOAP), but it aims to be largely independent of transport-level handling of data.
OGSA has been described as a refinement of a Web services architecture, specifically designed to support grid requirements.
The concept of OGSA is derived from work presented in the 2002 Globus Alliance paper "The Physiology of the Grid" by Ian Foster, Carl Kesselman, Jeffrey M. Nick, and Steven Tuecke.
It was developed by GGF working groups which resulted in a document, entitled The Open Grid Services Architecture, Version 1.5 in 2006.
The GGF published some use case scenarios.
According to the "Defining the Grid: A Roadmap for OGSA Standards v 1.0", OGSA is:
An architectural process in which the GGF's OGSA Working Group collects requirements and maintains a set of informational documents that describe the architecture;
A set of normative specifications and profiles that document the precise requirements for a conforming hardware or software component;
Software components that adhere to the OGSA specifications and profiles, enabling deployment of grid solutions that are interoperable even though they may be based on implementations from multiple sources.
The Open Grid Services Architecture, Version 1.5 described these capabilities:
Infrastructure services
Execution Management services
Data services
Resource Management services
Security serv |
https://en.wikipedia.org/wiki/Flanging | Flanging is an audio effect produced by mixing two identical signals together, one signal delayed by a small and (usually) gradually changing period, usually smaller than 20 milliseconds. This produces a swept comb filter effect: peaks and notches are produced in the resulting frequency spectrum, related to each other in a linear harmonic series. Varying the time delay causes these to sweep up and down the frequency spectrum. A flanger is an effects unit that creates this effect.
Part of the output signal is usually fed back to the input (a "re-circulating delay line"), producing a resonance effect which further enhances the intensity of the peaks and troughs. The phase of the fed-back signal is sometimes inverted, producing another variation on the flanger sound.
Origin
As an audio effect, a listener hears a "drainpipe" or "swoosh" or "jet plane" sweeping effect as shifting sum-and-difference harmonics are created analogous to use of a variable notch filter. The term "flanging" comes from one of the early methods of producing the effect. The finished music track is recorded simultaneously to two matching tape machines, then replayed with both decks in sync. The output from the two recorders is mixed to a third recorder. The engineer slows down one playback recorder by lightly pressing a finger on the flange (rim) of the supply reel. The "drainpipe" or subtle "swoosh" effect "sweeps" in one direction, and the playback of that recorder remains slightly behind the other when the finger is removed. By pressing a finger on the flange of the other deck, the effect sweeps back in the other direction as the decks progress towards being in sync. The Beatles' producer George Martin disputed this "reel flange" source, attributing the term to himself and John Lennon instead.
Despite claims over who originated flanging, Les Paul discovered the effect in the late 1940s and 1950s; however, he did most of his early phasing experiments with acetate disks on variable-speed reco |
https://en.wikipedia.org/wiki/Dynamic%20range%20compression | Dynamic range compression (DRC) or simply compression is an audio signal processing operation that reduces the volume of loud sounds or amplifies quiet sounds, thus reducing or compressing an audio signal's dynamic range. Compression is commonly used in sound recording and reproduction, broadcasting, live sound reinforcement and in some instrument amplifiers.
A dedicated electronic hardware unit or audio software that applies compression is called a compressor. In the 2000s, compressors became available as software plugins that run in digital audio workstation software. In recorded and live music, compression parameters may be adjusted to change the way they affect sounds. Compression and limiting are identical in process but different in degree and perceived effect. A limiter is a compressor with a high ratio and, generally, a short attack time.
Types
There are two types of compression, downward and upward. Both downward and upward compression reduce the dynamic range of an audio signal.
Downward compression reduces the volume of loud sounds above a certain threshold. The quiet sounds below the threshold remain unaffected. This is the most common type of compressor. A limiter can be thought of as an extreme form of downward compression as it compresses the sounds over the threshold especially hard.
Upward compression increases the volume of quiet sounds below a certain threshold. The louder sounds above the threshold remain unaffected.
Some compressors also have the ability to do the opposite of compression, namely expansion. Expansion increases the dynamic range of the audio signal. Like compression, expansion comes in two types, downward and upward.
Downward expansion make the quiet sounds below the threshold even quieter. A noise gate can be thought of as an extreme form of downward expansion as the noise gate make the quiet sounds (for instance: noise) quieter or even silent, depending on the floor setting.
Upward expansion make the louder sounds a |
https://en.wikipedia.org/wiki/SkyOS | SkyOS (Sky Operating System) is a discontinued prototype commercial, proprietary, graphical desktop operating system written for the x86 computer architecture. As of January 30, 2009 development was halted with no plans to resume its development. In August 2013, developer Robert Szeleney announced the release of a public beta on the SkyOS website. This allows public users to download a Live CD of the SkyOS operating system, for testing and to optionally install the system.
History
Development started in 1996 with the first version released in December 1997.
Up until version 4.x the OS was freely available. Starting with beta development of SkyOS 5 in 2003, users were required to pay US$30 to get access to beta releases.
SkyOS adapted new filesystem SkyFS based on OpenBFS in 2004 and its graphics subsystem was improved in 2006 with support for desktop compositing including double buffering and transparency. The OS also moved to ELF binaries then.
The last beta build 6947 was released in August 2008 and there was no status update for several months.
As the OS was mainly the work of one man, Robert Szeleney, there was increasing difficulty to add new device drivers.
Considering lack of development under Robert Szeleney, going open source was viewed by the tech press as the best option for SkyOS.
Although Szeleney tried to bypass the lack of drivers by using a new kernel based on Linux or NetBSD, and reported some progress in this regard, development has not resumed.
SkyOS website disappeared in 2013 and final public build from August 2008 was released for free shortly thereafter.
Features
Kernel
SkyOS is a Unix-like operating system with a monolithic kernel.
The OS supports multiple users and symmetric multiprocessing.
Graphics and GUI
SkyOS has an integrated graphics subsystem with support for desktop compositing including double buffering and transparency. SkyOS GUI also allows system-wide mouse gestures.
SkyFS
SkyFS is a fork of the OpenBFS filesystem.
Sk |
https://en.wikipedia.org/wiki/DVB-S | Digital Video Broadcasting – Satellite (DVB-S) is the original DVB standard for satellite television and dates from 1995, in its first release, while development lasted from 1993 to 1997. The first commercial applications were by Star TV in Asia and Galaxy in Australia, enabling digitally broadcast, satellite-delivered television to the public. DVB-S was the first DVB standard for satellite, defining the framing structure, channel coding and modulation for 11/12 GHz satellite services.
It is used via satellites serving every continent of the world. DVB-S is used in both multiple channel per carrier (MCPC) and single channel per carrier modes for broadcast network feeds as well as for direct-broadcast satellite services like Sky UK and Ireland via Astra in Europe, Dish Network and Globecast in the U.S. and Bell Satellite TV in Canada.
While the actual DVB-S standard only specifies physical link characteristics and framing, the overlaid transport stream delivered by DVB-S is mandated as MPEG-2, known as MPEG transport stream (MPEG-TS).
Some amateur television repeaters also use this mode in the 1.2 GHz amateur band.
References
DVB-S/S2
https://www.etsi.org/technologies/dvb-s-s2
DVB specifications
https://dvb.org/specifications/
ETSI EN 300 421 V1.1.2 (1997-08)
Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for 11/12 GHz satellite services
https://www.etsi.org/standards#page=1&search=EN%20300%20421&title=1&etsiNumber=1&content=0&version=0&onApproval=1&published=1&withdrawn=1&historical=1&isCurrent=1&superseded=1&startDate=1988-01-15&endDate=2023-02-13&harmonized=0&keyword=&TB=&stdType=&frequency=&mandate=&collection=&sort=1
External links
ETSI DVB-S/S2
DVB-S TR 101 198 V1.1.1 (09/97) Implementation of Binary Phase Shift Keying (BPSK) modulation in DVB satellite transmission systems
DVB-S EN 300 421 V1.1.2 (08/97) Framing structure, channel coding and modulation for 11/12 GHz satellite services
Irdeto history
Digital V |
https://en.wikipedia.org/wiki/Prill | A prill is a small aggregate or globule of a material, most often a dry sphere, formed from a melted liquid through spray crystallization. Prilled is a term used in mining and manufacturing to refer to a product that has been pelletized. ANFO explosive typically comprises ammonium nitrate prills mixed with #2 fuel oil. The pellets are a neater, simpler form for handling, with reduced dust.
The material to be prilled must be in a solid state at room temperature and a low-viscosity liquid when melted. Prills are formed by allowing drops of the melted prill substance to congeal or freeze in mid-air after being dripped from the top of a tall prilling tower. Certain agrochemicals such as urea are often supplied in prilled form. Fertilizers (ammonium nitrate, urea, NPK fertilizer) and some detergent powders are commonly manufactured as prills. However prilling of ammonium nitrate and urea has in recent years been replaced by fluid bed granulation as this gives strong and more abrasion-resistant granules.
Melted material may also be atomized and then allowed to form smaller prills that are useful in cosmetics, food, and animal feed.
See also
Shot (pellet)
References
Agricultural chemicals
Metallurgy |
https://en.wikipedia.org/wiki/John%20Glen%20Wardrop | John Glen Wardrop (1922–1989), born in Warwick, England, was an English mathematician and transport analyst who developed what became known as Wardrop's first and second principles of equilibrium in the field of traffic assignment.
He studied at Downing College, Cambridge, and worked in Operational Research at British Bomber Command during the Second World War. He then helped to set up, and later headed, the Traffic Section of the Road Research Laboratory near Slough (Part of the Directorate of Scientific and Industrial Research within the UK Civil Service) where he published his work on equilibrium. He subsequently followed Dr Reuben Smeed to University College London, becoming Reader Emeritus in Traffic Studies.
Wardrop equilibria
In studies about traffic assignment, network equilibrium models are commonly used for the prediction of traffic patterns in transportation networks that are subject to congestion. The idea of traffic equilibrium originated as early as 1924, with Frank Knight.
The concepts are related to the idea of Nash equilibrium in game theory developed separately. However, in transportation networks, there are many players, making the analysis complex.
In 1952, Wardrop stated two principles that formalize different notions of equilibrium, and introduced the alternative behaviour postulate of the minimization of the total travel costs:
Wardrop's first principle of route choice, now known as "user equilibrium", "selfish Wardrop equilibrium" or just "Wardrop equilibrium", which is identical to the notion postulated by Knight, became accepted as a sound and simple behavioural principle to describe the spreading of trips over alternate routes because of congested conditions. It states:
The journey times in all routes actually used are equal and less than those that would be experienced by a single vehicle on any unused route.
The traffic flows that satisfy this principle are usually referred to as "user equilibrium" (UE) flows, since each user |
https://en.wikipedia.org/wiki/Cantenna | A cantenna (a portmanteau blending the words can and antenna) is a homemade directional waveguide antenna, made out of an open-ended metal can.
Cantennas are typically used to increase the range (or discovery) of Wi-Fi networks.
Construction
The cylinder portion of the can may consist of metal-coated paperboard.
Although some designs are based on a Pringles potato chips can, this tube is too narrow to increase the 2.4 GHz signal by a useful amount, although at 5 GHz it would be about the right size. However, a cantenna can be made from various cans or tubes of an appropriate diameter. Some designs include a pole mount to elevate the cantenna.
At 2.4 GHz, losses can occur if the cable from the cantenna to the Wi-Fi circuitry is too long. A more efficient cantenna can be made by minimising this length or connecting the cantenna directly to the Wi-Fi circuitry.
Use
Cantennas are typically used for extending a wireless local area network (WLAN).
The tiny design makes them ideal for mobile applications such as wardriving.
Cantennas can be used to increase cell phone range, improve reception, and decrease noise.
A cantenna can be used as a satellite dish feed horn. The 5.5 GHz cantenna dimensions are almost perfect in that they make a good fit for the standard TV satellite dish. The resulting setup is a low-cost high-quality high-gain antenna. Such setups are widely used in wireless community networks for long-distance links.
Cantennas may be used with other RF devices such as wireless security cameras.
See also
WokFi
WarXing
References
External links
Extend your wireless network by building a Wi-Fi cantenna
Amateurlogic Episode 3 (Construction details for a more efficient cantenna)
Waveguide Can-tenna
Youtube video on How To Build A low loss Cantenna
Cantenna Calculator
Wireless networking
Radio frequency antenna types
Antennas (radio) |
https://en.wikipedia.org/wiki/Mushroom%20cloud | A mushroom cloud is a distinctive mushroom-shaped flammagenitus cloud of debris, smoke, and usually condensed water vapor resulting from a large explosion. The effect is most commonly associated with a nuclear explosion, but any sufficiently energetic detonation or deflagration will produce the same effect. They can be caused by powerful conventional weapons, like thermobaric weapons such as the ATBIP and GBU-43/B MOAB. Some volcanic eruptions and impact events can produce natural mushroom clouds.
Mushroom clouds result from the sudden formation of a large volume of lower-density gases at any altitude, causing a Rayleigh–Taylor instability. The buoyant mass of gas rises rapidly, resulting in turbulent vortices curling downward around its edges, forming a temporary vortex ring that draws up a central column, possibly with smoke, debris, condensed water vapor, or a combination of these, to form the "mushroom stem". The mass of gas plus entrained moist air eventually reaches an altitude where it is no longer of lower density than the surrounding air; at this point, it disperses, drifting back down (see fallout). The stabilization altitude depends strongly on the profiles of the temperature, dew point, and wind shear in the air at and above the starting altitude.
Early accounts and origins of term
Although the term appears to have been coined in the early 1950s, mushroom clouds generated by explosions were being described centuries before the atomic era.
A contemporary aquatint by an unknown artist of the 1782 Franco-Spanish attack on Gibraltar shows one of the attacking force's floating batteries exploding with a mushroom cloud after the British defenders set it ablaze by firing heated shot.
In 1798, Gerhard Vieth published a detailed and illustrated account of a cloud in the neighborhood of Gotha that was "not unlike a mushroom in shape". The cloud had been observed by legation counselor Lichtenberg a few years earlier on a warm summer afternoon. It was interpre |
https://en.wikipedia.org/wiki/Hand-waving | Hand-waving (with various spellings) is a pejorative label for attempting to be seen as effective – in word, reasoning, or deed – while actually doing nothing effective or substantial. It is often applied to debating techniques that involve fallacies, misdirection and the glossing over of details. It is also used academically to indicate unproven claims and skipped steps in proofs (sometimes intentionally, as in lectures and instructional materials), with some specific meanings in particular fields, including literary criticism, speculative fiction, mathematics, logic, science and engineering.
The term can additionally be used in work situations, when attempts are made to display productivity or assure accountability without actually resulting in them. The term can also be used as a self-admission of, and suggestion to defer discussion about, an allegedly unimportant weakness in one's own argument's evidence, to forestall an opponent dwelling on it. In debate competition, certain cases of this form of hand-waving may be explicitly permitted.
Hand-waving is an idiomatic metaphor, derived in part from the use of excessive gesticulation, perceived as unproductive, distracting or nervous, in communication or other effort. The term also evokes the sleight-of-hand distraction techniques of stage magic, and suggests that the speaker or writer seems to believe that if they, figuratively speaking, simply wave their hands, no one will notice or speak up about the holes in the reasoning. This implication of misleading intent has been reinforced by the pop-culture influence of the Star Wars franchise, in which mystically powerful hand-waving is fictionally used for mind control, and some uses of the term in public discourse are explicit Star Wars references.
Actual hand-waving motions may be used either by a speaker to indicate a desire to avoid going into details, or by critics to indicate that they believe the proponent of an argument is engaging in a verbal hand-wave in |
https://en.wikipedia.org/wiki/NetBIOS%20Frames | NetBIOS Frames (NBF) is a non-routable network- and transport-level data protocol most commonly used as one of the layers of Microsoft Windows networking in the 1990s. NBF or NetBIOS over IEEE 802.2 LLC is used by a number of network operating systems released in the 1990s, such as LAN Manager, LAN Server, Windows for Workgroups, Windows 95 and Windows NT. Other protocols, such as NBT (NetBIOS over TCP/IP), and NBX (NetBIOS-over-IPX/SPX) also implement the NetBIOS/NetBEUI services over other protocol suites.
The NBF protocol is broadly, but incorrectly, referred to as NetBEUI. This originates from the confusion with NetBIOS Extended User Interface, an extension to the NetBIOS API that was originally developed in conjunction with the NBF protocol; both the protocol and the NetBEUI emulator were originally developed to allow NetBIOS programs to run over IBM's new Token Ring network. Microsoft caused this confusion by labelling its NBF protocol implementation NetBEUI. NBF is a protocol and the original NetBEUI was a NetBIOS application programming interface extension.
Overview
NBF protocol uses 802.2 type 1 mode to provide the NetBIOS/NetBEUI name service and datagram service, and 802.2 type 2 mode to provide the NetBIOS/NetBEUI session service (virtual circuit). NBF protocol makes wide use of broadcast messages, which accounts for its reputation as a chatty interface. While the protocol consumes few network resources in a very small network, broadcasts begin to adversely impact performance and speed when the number of hosts present in a network grows.
Sytek developed NetBIOS for IBM for the PC-Network program and was used by Microsoft for MS-NET in 1985. In 1987, Microsoft and Novell utilized it for their network operating systems LAN Manager and NetWare.
Because NBF protocol is unroutable it can only be used to communicate with devices in the same broadcast domain, but being bridgeable it can also be used to communicate with network segments connected to each oth |
https://en.wikipedia.org/wiki/Spectrogram | A spectrogram is a visual representation of the spectrum of frequencies of a signal as it varies with time.
When applied to an audio signal, spectrograms are sometimes called sonographs, voiceprints, or voicegrams. When the data are represented in a 3D plot they may be called waterfall displays.
Spectrograms are used extensively in the fields of music, linguistics, sonar, radar, speech processing, seismology, and others. Spectrograms of audio can be used to identify spoken words phonetically, and to analyse the various calls of animals.
A spectrogram can be generated by an optical spectrometer, a bank of band-pass filters, by Fourier transform or by a wavelet transform (in which case it is also known as a scaleogram or scalogram).
A spectrogram is usually depicted as a heat map, i.e., as an image with the intensity shown by varying the colour or brightness.
Format
A common format is a graph with two geometric dimensions: one axis represents time, and the other axis represents frequency; a third dimension indicating the amplitude of a particular frequency at a particular time is represented by the intensity or color of each point in the image.
There are many variations of format: sometimes the vertical and horizontal axes are switched, so time runs up and down; sometimes as a waterfall plot where the amplitude is represented by height of a 3D surface instead of color or intensity. The frequency and amplitude axes can be either linear or logarithmic, depending on what the graph is being used for. Audio would usually be represented with a logarithmic amplitude axis (probably in decibels, or dB), and frequency would be linear to emphasize harmonic relationships, or logarithmic to emphasize musical, tonal relationships.
Generation
Spectrograms of light may be created directly using an optical spectrometer over time.
Spectrograms may be created from a time-domain signal in one of two ways: approximated as a filterbank that results from a series of band-pass filter |
https://en.wikipedia.org/wiki/SciPy | SciPy (pronounced "sigh pie") is a free and open-source Python library used for scientific computing and technical computing.
SciPy contains modules for optimization, linear algebra, integration, interpolation, special functions, FFT, signal and image processing, ODE solvers and other tasks common in science and engineering.
SciPy is also a family of conferences for users and developers of these tools: SciPy (in the United States), EuroSciPy (in Europe) and SciPy.in (in India). Enthought originated the SciPy conference in the United States and continues to sponsor many of the international conferences as well as host the SciPy website.
The SciPy library is currently distributed under the BSD license, and its development is sponsored and supported by an open community of developers. It is also supported by NumFOCUS, a community foundation for supporting reproducible and accessible science.
Components
The SciPy package is at the core of Python's scientific computing capabilities. Available sub-packages include:
cluster: hierarchical clustering, vector quantization, K-means
constants: physical constants and conversion factors
fft: Discrete Fourier Transform algorithms
fftpack: Legacy interface for Discrete Fourier Transforms
integrate: numerical integration routines
interpolate: interpolation tools
io: data input and output
linalg: linear algebra routines
misc: miscellaneous utilities (e.g. example images)
ndimage: various functions for multi-dimensional image processing
ODR: orthogonal distance regression classes and algorithms
optimize: optimization algorithms including linear programming
signal: signal processing tools
sparse: sparse matrices and related algorithms
spatial: algorithms for spatial structures such as k-d trees, nearest neighbors, Convex hulls, etc.
special: special functions
stats: statistical functions
weave: tool for writing C/C++ code as Python multiline strings (now deprecated in favor of Cython)
Data structures
The basic dat |
https://en.wikipedia.org/wiki/Trans%20fat%20regulation | Trans fat regulation, that aims to limit the amount of "trans fat" — fat containing trans fatty acids — in industrial food products, has been enacted in many countries. These regulations were motivated by numerous studies that pointed to significant negative health effects of trans fat. It is generally accepted that trans fat in the diet is a contributing factor in several diseases, including cardiovascular disease, diabetes, and cancer.
History
As early as 1956, there were suggestions in the scientific literature that trans fats could be a cause of the large increase in coronary artery disease but after three decades the concerns were still largely unaddressed. Instead, by the 1980s, fats of animal origin had become one of the greatest concerns of dieticians. Activists, such as Phil Sokolof, who took out full page ads in major newspapers, attacked the use of beef tallow in McDonald's french fries and urged fast-food companies to switch to vegetable oils. The result was an almost overnight switch by most fast-food outlets to trans fats.
Studies in the early 1990s, however, brought renewed scrutiny and confirmation of the negative health impact of trans fats. In 1994, it was estimated that trans fats caused 20,000 deaths annually in the United States from heart disease.
Mandatory food labeling for trans fats was introduced in several countries. Campaigns were launched by activists to bring attention to the issue and change the practices of food manufacturers.
International regulation
The international trade in food is standardized in the Codex Alimentarius. Hydrogenated oils and fats come under the scope of Codex Stan 19. Non-dairy fat spreads are covered by Codex Stan 256-2007. In the Codex Alimentarius, trans fat to be labelled as such is defined as the geometrical isomers of monounsaturated and polyunsaturated fatty acids having non-conjugated [interrupted by at least one methylene group (−CH2−)] carbon-carbon double bonds in the trans configuration. This |
https://en.wikipedia.org/wiki/MorphOS | MorphOS is an AmigaOS-like computer operating system (OS). It is a mixed proprietary and open source OS produced for the Pegasos PowerPC (PPC) processor based computer, PowerUP accelerator equipped Amiga computers, and a series of Freescale development boards that use the Genesi firmware, including the Efika and mobileGT. Since MorphOS 2.4, Apple's Mac mini G4 is supported as well, and with the release of MorphOS 2.5 and MorphOS 2.6 the eMac and Power Mac G4 models are respectively supported. The release of MorphOS 3.2 added limited support for Power Mac G5. The core, based on the Quark microkernel, is proprietary, although several libraries and other parts are open source, such as the Ambient desktop.
Characteristics and versions
Developed for PowerPC CPUs from Freescale and IBM, it also supports the original AmigaOS Motorola 68000 series (68k, MC680x0) applications via proprietary task-based emulation, and most AmigaOS PPC applications via API wrappers. It is API compatible with AmigaOS 3.1 and has a GUI based on the Magic User Interface (MUI).
Besides the Pegasos version of MorphOS, there is a version for Amiga computers equipped with PowerUP accelerator cards produced by Phase5. This version is free, as is registration. If unregistered, it slows down after each two-hour session. PowerUP MorphOS was most recently updated on 23 February 2006; however, it does not exceed the feature set or advancement of the Pegasos release.
A version of MorphOS for the Efika, a very small mainboard based on the ultra-low-power MPC5200B processor from Freescale, has been shown at exhibitions and user gatherings in Germany. Current (since 2.0) release of MorphOS supports the Efika.
Components
ABox
ABox is an emulation sandbox featuring a PPC native AmigaOS API clone that is binary compatible with both 68k Amiga applications and both PowerUP and WarpOS formats of Amiga PPC executables. ABox is based in part on AROS Research Operating System. ABox includes Trance JIT code transla |
https://en.wikipedia.org/wiki/A20%20line | The A20, or address line 20, is one of the electrical lines that make up the system bus of an x86-based computer system. The A20 line in particular is used to transmit the 21st bit on the address bus.
A microprocessor typically has a number of address lines equal to the base-two logarithm of the number of words in its physical address space. For example, a processor with 4 GB of byte-addressable physical space requires 32 lines (log2(4 GB) = log2(232 B) = 32), which are named A0 through A31. The lines are named after the zero-based number of the bit in the address that they are transmitting. The least significant bit is first and is therefore numbered bit 0 and signaled on line A0. A20 transmits bit 20 (the 21st bit) and becomes active once addresses reach 1 MB, or 220.
Overview
The Intel 8086, Intel 8088, and Intel 80186 processors had 20 address lines, numbered A0 to A19; with these, the processor can access 220 bytes, or 1 MB. Internal address registers of such processors only had 16 bits. To access a 20-bit address space, an external memory reference was made up of a 16-bit offset address added to a 16-bit segment number, shifted 4 bits to the left so as to produce a 20-bit physical address. The resulting address is equal to segment × 16 + offset. There are many combinations of segment and offset that produce the same 20-bit physical address. Therefore, there were various ways to address the same byte in memory. For example, here are four of the 4096 different segment:offset combinations, all referencing the byte whose physical address is 0x000FFFFF (the last byte in 1 MB-memory space):
F000:FFFF
FFFF:000F
F555:AAAF
F800:7FFF
Referenced the last way, an increase of one in the offset yields F800:8000, which is a proper address for the processor, but since it translates to the physical address 0x00100000 (the first byte over 1 MB), the processor would need another address line for actual access to that byte. Since there is no such line on the 8086 line o |
https://en.wikipedia.org/wiki/Rack%20and%20pinion | A rack and pinion is a type of linear actuator that comprises a circular gear (the pinion) engaging a linear gear (the rack). Together, they convert rotational motion into linear motion. Rotating the pinion causes the rack to be driven in a line. Conversely, moving the rack linearly will cause the pinion to rotate. A rack and pinion drive can use both straight and helical gears. Though some suggest helical gears are quieter in operation, no hard evidence supports this theory. Helical racks, while being more affordable, have proven to increase side torque on the datums, increasing operating temperature leading to premature wear. Straight racks require a lower driving force and offer increased torque and speed per percentage of gear ratio which allows lower operating temperature and lessens viscal friction and energy use. The maximum force that can be transmitted in a rack and pinion mechanism is determined by the tooth pitch and the size of the pinion as well as the gear ratio.
For example, in a rack railway, the rotation of a pinion mounted on a locomotive or a railroad car engages a rack placed between the rails and helps to move the train up a steep gradient.
For every pair of conjugate involute profile, there is a basic rack. This basic rack is the profile of the conjugate gear of infinite pitch radius (i.e. a toothed straight edge).
A generating rack is a rack outline used to indicate tooth details and dimensions for the design of a generating tool, such as a hob or a gear shaper cutter.
Applications
Rack and pinion combinations are often used as part of a simple linear actuator, where the rotation of a shaft powered by hand or by a motor is converted to linear motion.
The rack carries the full load of the actuator directly and so the driving pinion is usually small, so that the gear ratio reduces the torque required. This force, thus torque, may still be substantial and so it is common for there to be a reduction gear immediately before this by either a |
https://en.wikipedia.org/wiki/Differential%20operator | In mathematics, a differential operator is an operator defined as a function of the differentiation operator. It is helpful, as a matter of notation first, to consider differentiation as an abstract operation that accepts a function and returns another function (in the style of a higher-order function in computer science).
This article considers mainly linear differential operators, which are the most common type. However, non-linear differential operators also exist, such as the Schwarzian derivative.
Definition
Given a nonnegative integer m, an order- linear differential operator is a map from a function space to another function space that can be written as:
where is a multi-index of non-negative integers, , and for each , is a function on some open domain in n-dimensional space. The operator is interpreted as
Thus for a function :
The notation is justified (i.e., independent of order of differentiation) because of the symmetry of second derivatives.
The polynomial p obtained by replacing D by variables in P is called the total symbol of P; i.e., the total symbol of P above is:
where The highest homogeneous component of the symbol, namely,
is called the principal symbol of P. While the total symbol is not intrinsically defined, the principal symbol is intrinsically defined (i.e., it is a function on the cotangent bundle).
More generally, let E and F be vector bundles over a manifold X. Then the linear operator
is a differential operator of order if, in local coordinates on X, we have
where, for each multi-index α, is a bundle map, symmetric on the indices α.
The kth order coefficients of P transform as a symmetric tensor
whose domain is the tensor product of the kth symmetric power of the cotangent bundle of X with E, and whose codomain is F. This symmetric tensor is known as the principal symbol (or just the symbol) of P.
The coordinate system xi permits a local trivialization of the cotangent bundle by the coordinate differenti |
https://en.wikipedia.org/wiki/Evanescent%20field | In electromagnetics, an evanescent field, or evanescent wave, is an oscillating electric and/or magnetic field that does not propagate as an electromagnetic wave but whose energy is spatially concentrated in the vicinity of the source (oscillating charges and currents). Even when there is a propagating electromagnetic wave produced (e.g., by a transmitting antenna), one can still identify as an evanescent field the component of the electric or magnetic field that cannot be attributed to the propagating wave observed at a distance of many wavelengths (such as the far field of a transmitting antenna).
A hallmark of an evanescent field is that there is no net energy flow in that region. Since the net flow of electromagnetic energy is given by the average Poynting vector, this means that the Poynting vector in these regions, as averaged over a complete oscillation cycle, is zero.
Use of the term
In many cases one cannot simply say that a field is or is not "evanescent" – having the Poynting vector average to zero in some direction (or all directions).
In most cases where they exist, evanescent fields are simply thought of and referred to the same as all other electric or magnetic fields involved, without any special recognition of those fields' evanescence. The term's use is mostly limited to distinguishing a part of a field or solution in those cases where one might only expect the fields of a propagating wave.
For instance, in the illustration at the top of the article, energy is indeed carried in the horizontal direction. However, in the vertical direction, the field strength drops off exponentially with increasing distance above the surface. This leaves most of the field concentrated in a thin boundary layer very close to the interface; for that reason, it is referred to as a surface wave. However, despite energy flowing horizontally, along the vertical there is no net propagation of energy away from (or toward) the surface, so that one could properly describe |
https://en.wikipedia.org/wiki/History%20of%20computing%20hardware%20%281960s%E2%80%93present%29 | The history of computing hardware starting at 1960 is marked by the conversion from vacuum tube to solid-state devices such as transistors and then integrated circuit (IC) chips. Around 1953 to 1959, discrete transistors started being considered sufficiently reliable and economical that they made further vacuum tube computers uncompetitive. Metal–oxide–semiconductor (MOS) large-scale integration (LSI) technology subsequently led to the development of semiconductor memory in the mid-to-late 1960s and then the microprocessor in the early 1970s. This led to primary computer memory moving away from magnetic-core memory devices to solid-state static and dynamic semiconductor memory, which greatly reduced the cost, size, and power consumption of computers. These advances led to the miniaturized personal computer (PC) in the 1970s, starting with home computers and desktop computers, followed by laptops and then mobile computers over the next several decades.
Second generation
For the purposes of this article, the term "second generation" refers to computers using discrete transistors, even when the vendors referred to them as "third-generation". By 1960 transistorized computers were replacing vacuum tube computers, offering lower cost, higher speeds, and reduced power consumption. The marketplace was dominated by IBM and the seven dwarfs:
IBM
The BUNCH
Burroughs
UNIVAC
NCR
Control Data Corporation (CDC)
Honeywell
General Electric
RCA.
Some examples of 1960s second generation computers from those vendors are:
the IBM 1401, the IBM 7090/7094, and the IBM System/360;
the Burroughs 5000 series;
the UNIVAC 1107;
the NCR 315;
the CDC 1604 and the CDC 3000 series;
the Honeywell 200, Honeywell 400, and Honeywell 800;
the GE-400 series and the GE-600 series;
the RCA 301, 3301 and the Spectra 70 series.
However, some smaller companies made significant contributions. Also, towards the end of the second generation Digital Equipment Corporation (DEC) was a serio |
https://en.wikipedia.org/wiki/Kombucha | Kombucha (also tea mushroom, tea fungus, or Manchurian mushroom when referring to the culture; Latin name Medusomyces gisevii) is a fermented, lightly effervescent, sweetened black tea drink commonly consumed for its purported health benefits. Sometimes the beverage is called kombucha tea to distinguish it from the culture of bacteria and yeast. Juice, spices, fruit or other flavorings are often added.
Kombucha is thought to have originated in China, where the drink is traditional. By the early 20th century it spread to Russia, then other parts of Eastern Europe and Germany. Kombucha is now homebrewed globally, and also bottled and sold commercially. The global kombucha market was worth approximately billion .
Kombucha is produced by symbiotic fermentation of sugared tea using a symbiotic culture of bacteria and yeast (SCOBY) commonly called a "mother" or "mushroom". The microbial populations in a SCOBY vary. The yeast component generally includes Saccharomyces cerevisiae, along with other species; the bacterial component almost always includes Gluconacetobacter xylinus to oxidize yeast-produced alcohols to acetic acid (and other acids). Although the SCOBY is commonly called "tea fungus" or "mushroom", it is actually "a symbiotic growth of acetic acid bacteria and osmophilic yeast species in a zoogleal mat ". The living bacteria are said to be probiotic, one of the reasons for the popularity of the drink.
Numerous health benefits have been claimed to correlate with drinking kombucha; there is little evidence to support any of these claims. The beverage has caused rare serious adverse effects, possibly arising from contamination during home preparation. It is not recommended for therapeutic purposes.
History
Kombucha most likely originated in the Bohai Sea district in China. The drink was consumed in Russia and from there entered the rest of Europe. Its consumption increased in the United States during the early 21st century. Having an alcohol content of less th |
https://en.wikipedia.org/wiki/Archimedean%20property | In abstract algebra and analysis, the Archimedean property, named after the ancient Greek mathematician Archimedes of Syracuse, is a property held by some algebraic structures, such as ordered or normed groups, and fields.
The property, typically construed, states that given two positive numbers and , there is an integer such that . It also means that the set of natural numbers is not bounded above. Roughly speaking, it is the property of having no infinitely large or infinitely small elements. It was Otto Stolz who gave the axiom of Archimedes its name because it appears as Axiom V of Archimedes’ On the Sphere and Cylinder.
The notion arose from the theory of magnitudes of Ancient Greece; it still plays an important role in modern mathematics such as David Hilbert's axioms for geometry, and the theories of ordered groups, ordered fields, and local fields.
An algebraic structure in which any two non-zero elements are comparable, in the sense that neither of them is infinitesimal with respect to the other, is said to be Archimedean.
A structure which has a pair of non-zero elements, one of which is infinitesimal with respect to the other, is said to be non-Archimedean.
For example, a linearly ordered group that is Archimedean is an Archimedean group.
This can be made precise in various contexts with slightly different formulations.
For example, in the context of ordered fields, one has the axiom of Archimedes which formulates this property, where the field of real numbers is Archimedean, but that of rational functions in real coefficients is not.
History and origin of the name of the Archimedean property
The concept was named by Otto Stolz (in the 1880s) after the ancient Greek geometer and physicist Archimedes of Syracuse.
The Archimedean property appears in Book V of Euclid's Elements as Definition 4:
Because Archimedes credited it to Eudoxus of Cnidus it is also known as the "Theorem of Eudoxus" or the Eudoxus axiom.
Archimedes used infinitesimals i |
https://en.wikipedia.org/wiki/Archimedean%20group | In abstract algebra, a branch of mathematics, an Archimedean group is a linearly ordered group for which the Archimedean property holds: every two positive group elements are bounded by integer multiples of each other. The set R of real numbers together with the operation of addition and the usual ordering relation between pairs of numbers is an Archimedean group. By a result of Otto Hölder, every Archimedean group is isomorphic to a subgroup of this group. The name "Archimedean" comes from Otto Stolz, who named the Archimedean property after its appearance in the works of Archimedes.
Definition
An additive group consists of a set of elements, an associative addition operation that combines pairs of elements and returns a single element,
an identity element (or zero element) whose sum with any other element is the other element, and an additive inverse operation such that the sum of any element and its inverse is zero.
A group is a linearly ordered group when, in addition, its elements can be linearly ordered in a way that is compatible with the group operation: for all elements x, y, and z, if x ≤ y then x + z ≤ y + z and z + x ≤ z + y.
The notation na (where n is a natural number) stands for the group sum of n copies of a.
An Archimedean group (G, +, ≤) is a linearly ordered group subject to the following additional condition, the Archimedean property: For every a and b in G which are greater than 0, it is possible to find a natural number n for which the inequality b ≤ na holds.
An equivalent definition is that an Archimedean group is a linearly ordered group without any bounded cyclic subgroups: there does not exist a cyclic subgroup S and an element x with x greater than all elements in S. It is straightforward to see that this is equivalent to the other definition: the Archimedean property for a pair of elements a and b is just the statement that the cyclic subgroup generated by a is not bounded by b.
Examples of Archimedean groups
The sets of the integer |
https://en.wikipedia.org/wiki/Superuser | In computing, the superuser is a special user account used for system administration. Depending on the operating system (OS), the actual name of this account might be root, administrator, admin or supervisor. In some cases, the actual name of the account is not the determining factor; on Unix-like systems, for example, the user with a user identifier (UID) of zero is the superuser, regardless of the name of that account; and in systems which implement a role based security model, any user with the role of superuser (or its synonyms) can carry out all actions of the superuser account.
The principle of least privilege recommends that most users and applications run under an ordinary account to perform their work, as a superuser account is capable of making unrestricted, potentially adverse, system-wide changes.
Unix and Unix-like
In Unix-like computer OSes (such as Linux), root is the conventional name of the user who has all rights or permissions (to all files and programs) in all modes (single- or multi-user). Alternative names include baron in BeOS and avatar on some Unix variants. BSD often provides a toor ("root" written backward) account in addition to a root account. Regardless of the name, the superuser always has a user ID of 0. The root user can do many things an ordinary user cannot, such as changing the ownership of files and binding to network ports numbered below 1024.
The name root may have originated because root is the only user account with permission to modify the root directory of a Unix system. This directory was originally considered to be root's home directory, but the UNIX Filesystem Hierarchy Standard now recommends that root's home be at . The first process bootstrapped in a Unix-like system, usually called , runs with root privileges. It spawns all other processes directly or indirectly, which inherit their parents' privileges. Only a process running as root is allowed to change its user ID to that of another user; once it has done so, t |
https://en.wikipedia.org/wiki/Zero%20of%20a%20function | In mathematics, a zero (also sometimes called a root) of a real-, complex-, or generally vector-valued function , is a member of the domain of such that vanishes at ; that is, the function attains the value of 0 at , or equivalently, is the solution to the equation . A "zero" of a function is thus an input value that produces an output of 0.
A root of a polynomial is a zero of the corresponding polynomial function. The fundamental theorem of algebra shows that any non-zero polynomial has a number of roots at most equal to its degree, and that the number of roots and the degree are equal when one considers the complex roots (or more generally, the roots in an algebraically closed extension) counted with their multiplicities. For example, the polynomial of degree two, defined by has the two roots (or zeros) that are 2 and 3.
If the function maps real numbers to real numbers, then its zeros are the -coordinates of the points where its graph meets the x-axis. An alternative name for such a point in this context is an -intercept.
Solution of an equation
Every equation in the unknown may be rewritten as
by regrouping all the terms in the left-hand side. It follows that the solutions of such an equation are exactly the zeros of the function . In other words, a "zero of a function" is precisely a "solution of the equation obtained by equating the function to 0", and the study of zeros of functions is exactly the same as the study of solutions of equations.
Polynomial roots
Every real polynomial of odd degree has an odd number of real roots (counting multiplicities); likewise, a real polynomial of even degree must have an even number of real roots. Consequently, real odd polynomials must have at least one real root (because the smallest odd whole number is 1), whereas even polynomials may have none. This principle can be proven by reference to the intermediate value theorem: since polynomial functions are continuous, the function value must cross zero, in the |
https://en.wikipedia.org/wiki/Sky%20Tower%20%28Auckland%29 | The Sky Tower is a telecommunications and observation tower in Auckland, New Zealand. Located at the corner of Victoria and Federal Streets within the city's CBD, it is tall, as measured from ground level to the top of the mast, making it the second tallest freestanding structure in the Southern Hemisphere, surpassed by Autograph Tower in Jakarta, Indonesia, and the 28th tallest tower in the world. Since its completion in 1997, the Sky Tower has become an iconic landmark in Auckland's skyline, due to its height and design.
The tower is part of the SkyCity Auckland casino complex, originally built in 1994–1997 for Harrah's Entertainment. Several upper levels are accessible to the public, attracting an average of 1,150 visitors per day (over 415,000 per year).
Public facilities
The Sky Tower has several upper levels that are accessible to the public:
Level 50: Sky Cafe
Level 51: Main Observation Deck
Level 52: Orbit 360° Dining
Level 53: The Sugar Club restaurant, SkyWalk and SkyJump
Level 60: Sky Deck
The upper portion of the tower contains two restaurants and a cafe; including New Zealand's only revolving restaurant, located from the ground, which turns 360 degrees every hour. There is also a brasserie-style buffet located one floor above the main observatory level. It has three observation decks at different heights, each providing 360-degree views of the city. The main observation level at has thick glass sections of flooring giving a view straight to the ground. The top observation deck labeled "Skydeck" sits just below the main antenna at and gives views of up to in the distance.
The tower also features the "SkyJump", a jump from the observation deck, during which a jumper can reach up to . The jump is guide-cable-controlled to prevent jumpers from colliding with the tower in case of wind gusts. Climbs into the antenna mast portion ( heights) are also possible for tour groups, as is a walk around the exterior.
Construction
Project history
Th |
https://en.wikipedia.org/wiki/Bitwise%20operation | In computer programming, a bitwise operation operates on a bit string, a bit array or a binary numeral (considered as a bit string) at the level of its individual bits. It is a fast and simple action, basic to the higher-level arithmetic operations and directly supported by the processor. Most bitwise operations are presented as two-operand instructions where the result replaces one of the input operands.
On simple low-cost processors, typically, bitwise operations are substantially faster than division, several times faster than multiplication, and sometimes significantly faster than addition. While modern processors usually perform addition and multiplication just as fast as bitwise operations due to their longer instruction pipelines and other architectural design choices, bitwise operations do commonly use less power because of the reduced use of resources.
Bitwise operators
In the explanations below, any indication of a bit's position is counted from the right (least significant) side, advancing left. For example, the binary value 0001 (decimal 1) has zeroes at every position but the first (i.e., the rightmost) one.
NOT
The bitwise NOT, or bitwise complement, is a unary operation that performs logical negation on each bit, forming the ones' complement of the given binary value. Bits that are 0 become 1, and those that are 1 become 0. For example:
NOT 0111 (decimal 7)
= 1000 (decimal 8)
NOT 10101011 (decimal 171)
= 01010100 (decimal 84)
The result is equal to the two's complement of the value minus one. If two's complement arithmetic is used, then NOT x = -x − 1.
For unsigned integers, the bitwise complement of a number is the "mirror reflection" of the number across the half-way point of the unsigned integer's range. For example, for 8-bit unsigned integers, NOT x = 255 - x, which can be visualized on a graph as a downward line that effectively "flips" an increasing range from 0 to 255, to a decreasing range from 255 to 0. A simple but illus |
https://en.wikipedia.org/wiki/Electronic%20business | Electronic business (also known as online business or e-business) is any kind of business or commercial transaction that includes sharing information across the internet. Commerce constitutes the exchange of products and services between businesses, groups, and individuals and can be seen as one of the essential activities of any business.
Electronic commerce focuses on the use of information and communication technology to enable the external activities and relationships of the business with individuals, groups, and other businesses, while e-business refers to business with help of the internet. Electronic business differs from electronic commerce as it does not only deal with online transactions of selling and buying of a product and/or service but also enables to conduct of business processes (inbound/outbound logistics, manufacturing & operations, marketing and sales, customer service) within the value chain through internal or external networks. The term "e-business" was coined by IBM's marketing and Internet team in 1996.
Market participants in Electronic Business
Electronic business can take place between a very large number of market participants; it can be between business and consumer, private individuals, public administrations, or any other organizations such as NGOs.
These various market participants can be divided into three main groups:
1) Business (B)
2) Consumer (C)
3) Administration (A)
All of them can be either buyers or service providers within the market. There are nine possible combinations for electronic business relationships. B2C and B2B belong to E-commerce, while A2B and A2A belong to the E-government sector which is also a part of the electronic business.
History
One of the founding pillars of electronic business was the development of the Electronic Data Interchange (EDI) electronic data interchange. This system replaced traditional mailing and faxing of documents with a digital transfer of data from one computer to another, withou |
https://en.wikipedia.org/wiki/Syntax%20error | In computer science, a syntax error is an error in the syntax of a sequence of characters or tokens that is intended to be written in a particular programming language.
For compiled languages, syntax errors are detected at compile-time. A program will not compile until all syntax errors are corrected. For interpreted languages, however, a syntax error may be detected during program execution, and an interpreter's error messages might not differentiate syntax errors from errors of other kinds.
There is some disagreement as to just what errors are "syntax errors". For example, some would say that the use of an uninitialized variable's value in Java code is a syntax error, but many others would disagree and would classify this as a (static) semantic error.
In 8-bit home computers that used BASIC interpreter as their primary user interface, the error message became somewhat notorious, as this was the response to any command or user input the interpreter could not parse.
A syntax error can occur or take place, when an invalid equation is being typed on a calculator. This can be caused, for instance, by opening brackets without closing them, or less commonly, entering several decimal points in one number.
In Java the following is a syntactically correct statement:
System.out.println("Hello World");
while the following is not:
System.out.println(Hello World);
The second example would theoretically print the variable Hello World instead of the words "Hello World". However, a variable in Java cannot have a space in between, so the syntactically correct line would be System.out.println(Hello_World).
A compiler will flag a syntax error when given source code that does not meet the requirements of the language's grammar.
Type errors (such as an attempt to apply the ++ increment operator to a boolean variable in Java) and undeclared variable errors are sometimes considered to be syntax errors when they are detected at compile-time. However, it is common to classify such |
https://en.wikipedia.org/wiki/Remanence | Remanence or remanent magnetization or residual magnetism is the magnetization left behind in a ferromagnetic material (such as iron) after an external magnetic field is removed. Colloquially, when a magnet is "magnetized", it has remanence. The remanence of magnetic materials provides the magnetic memory in magnetic storage devices, and is used as a source of information on the past Earth's magnetic field in paleomagnetism. The word remanence is from remanent + -ence, meaning "that which remains".
The equivalent term residual magnetization is generally used in engineering applications. In transformers, electric motors and generators a large residual magnetization is not desirable (see also electrical steel) as it is an unwanted contamination, for example a magnetization remaining in an electromagnet after the current in the coil is turned off. Where it is unwanted, it can be removed by degaussing.
Sometimes the term retentivity is used for remanence measured in units of magnetic flux density.
Types
Saturation remanence
The default definition of magnetic remanence is the magnetization remaining in zero field after a large magnetic field is applied (enough to achieve saturation). The effect of a magnetic hysteresis loop is measured using instruments such as a vibrating sample magnetometer; and the zero-field intercept is a measure of the remanence. In physics this measure is converted to an average magnetization (the total magnetic moment divided by the volume of the sample) and denoted in equations as Mr. If it must be distinguished from other kinds of remanence, then it is called the saturation remanence or saturation isothermal remanence (SIRM) and denoted by Mrs.
In engineering applications the residual magnetization is often measured using a B-H analyzer, which measures the response to an AC magnetic field (as in Fig. 1). This is represented by a flux density Br. This value of remanence is one of the most important parameters characterizing permanent ma |
https://en.wikipedia.org/wiki/Deluxe%20Paint | Deluxe Paint, often referred to as DPaint, is a bitmap graphics editor created by Dan Silva for Electronic Arts and published for the then-new Amiga 1000 in November 1985. A series of updated versions followed, some of which were ported to other platforms. An MS-DOS release with support for the 256 color VGA standard became popular for creating pixel graphics in video games in the 1990s.
Author Dan Silva previously worked on the Cut & Paste word processor (1984), also from Electronic Arts.
History
Deluxe Paint began as an in-house art development tool called Prism. As author Dan Silva added features to Prism, it was developed as a showcase product to coincide with the Amiga's debut in 1985. Upon release, it was quickly embraced by the Amiga community and became the de facto graphics (and later animation) editor for the platform. Amiga manufacturer Commodore International later commissioned EA to create version 4.5 AGA to bundle with the new Advanced Graphics Architecture chipset (A1200, A4000) capable Amigas. Version 5 was the last release after Commodore's bankruptcy in 1994.
Early versions of Deluxe Paint were available in protected and non copy-protected versions, the latter retailing for a slightly higher price. The copy protection scheme was later dropped. Deluxe Paint was first in a series of products from the Electronic Arts Tools group—then later moved to the ICE (for Interactivity, Creativity, and Education) group—which included such Amiga programs as Deluxe Music Construction Set (preceded by Music Construction Set for the Apple II), Deluxe Video, and the Studio series of paint programs for the Mac.
With the development of Deluxe Paint, EA introduced the ILBM and ANIM file format standards for graphics. While widely used on the Amiga, these formats never gained widespread end user acceptance on other platforms, but were heavily used by game development companies. Deluxe Paint was used by LucasArts to make graphics for their adventure games such as The |
https://en.wikipedia.org/wiki/Unsaturated%20fat | An unsaturated fat is a fat or fatty acid in which there is at least one double bond within the fatty acid chain. A fatty acid chain is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond.
A saturated fat has no carbon to carbon double bonds, so the maximum possible number of hydrogens bonded to the carbons, and is "saturated" with hydrogen atoms. To form carbon to carbon double bonds, hydrogen atoms are removed from the carbon chain. In cellular metabolism, unsaturated fat molecules contain less energy (i.e., fewer calories) than an equivalent amount of saturated fat. The greater the degree of unsaturation in a fatty acid (i.e., the more double bonds in the fatty acid) the more vulnerable it is to lipid peroxidation (rancidity). Antioxidants can protect unsaturated fat from lipid peroxidation.
Composition of common fats
In chemical analysis, fats are broken down to their constituent fatty acids, which can be analyzed in various ways. In one approach, fats undergo transesterification to give fatty acid methyl esters (FAMEs), which are amenable to separation and quantitation using by gas chromatography. Classically, unsaturated isomers were separated and identified by argentation thin-layer chromatography.
The saturated fatty acid components are almost exclusively stearic (C18) and palmitic acids (C16). Monounsaturated fats are almost exclusively oleic acid. Linolenic acid comprises most of the triunsaturated fatty acid component.
Chemistry and nutrition
Although polyunsaturated fats are protective against cardiac arrhythmias, a study of post-menopausal women with a relatively low fat intake showed that polyunsaturated fat is positively associated with progression of coronary atherosclerosis, whereas monounsaturated fat is not. This probably is an indication of the greater vulnerability of polyunsaturated fats to lipid peroxidation, against which vitamin E has been shown to be protective.
Examples |
https://en.wikipedia.org/wiki/Server%20farm | A server farm or server cluster is a collection of computer servers, usually maintained by an organization to supply server functionality far beyond the capability of a single machine. They often consist of thousands of computers which require a large amount of power to run and to keep cool. At the optimum performance level, a server farm has enormous financial and environmental costs.
They often include backup servers that can take over the functions of primary servers that may fail. Server farms are typically collocated with the network switches and/or routers that enable communication between different parts of the cluster and the cluster's users. Server "farmers" typically mount computers, routers, power supplies and related electronics on 19-inch racks in a server room or data center.
Applications
Server farms are commonly used for cluster computing. Many modern supercomputers comprise giant server farms of high-speed processors connected by either Gigabit Ethernet or custom interconnects such as Infiniband or Myrinet. Web hosting is a common use of a server farm; such a system is sometimes collectively referred to as a web farm. Other uses of server farms include scientific simulations (such as computational fluid dynamics) and the rendering of 3D computer generated imagery (see render farm).
Server farms are increasingly being used instead of or in addition to mainframe computers by large enterprises. In large server farms, the failure of an individual machine is a commonplace event: large server farms provide redundancy, automatic failover, and rapid reconfiguration of the server cluster.
Performance
The performance of the largest server farms (thousands of processors and up) is typically limited by the performance of the data center's cooling systems and the total electricity cost rather than by the processors' performance. Computers in server farms run 24/7 and consume large amounts of electricity. For this reason, the critical design parameter for bot |
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