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https://en.wikipedia.org/wiki/Monoplegia | Monoplegia is paralysis of a single limb, usually an arm. Common symptoms associated with monoplegic patients are weakness, numbness, and pain in the affected limb. Monoplegia is a type of paralysis that falls under hemiplegia. While hemiplegia is paralysis of half of the body, monoplegia is localized to a single limb or to a specific region of the body. Monoplegia of the upper limb is sometimes referred to as brachial monoplegia, and that of the lower limb is called crural monoplegia. Monoplegia in the lower extremities is not as common of an occurrence as in the upper extremities. Monoparesis is a similar, but less severe, condition because one limb is very weak, not paralyzed. For more information, see paresis.
Many conditions that cause paraplegia or quadriplegia begin as monoplegia. Thus, the diagnosis of spinal paraplegia must also be consulted. In addition, multiple cerebral disorders that cause hemiplegia may begin as monoplegia. Monoplegia is also frequently associated with, and considered to be the mildest form of, cerebral palsy.
Signs and symptoms
There are a number of symptoms associated with monoplegia. Curling of the hands or stiffness of the feet, weakness, spasticity, numbness, paralysis, pain in the affected limb, headaches, and shoulder pain are all considered to be symptoms of monoplegia. Patients of monoplegia typically feel symptoms of weakness and loss of sensation in the affected extremity, usually an arm. Despite these symptoms, the extremity with paralysis continues to maintain a strong pulse.
While chronic progressive brachial monoplegia is uncommon, syringomyelia and tumors of the cervical cord or brachial plexus may be the cause. The onset of brachial plexus paralysis is usually explosive where pain is the initial feature. Pain localizes to the shoulder but may be more diffuse, or could be limited to the lower arm. Pain is severe and often described as sharp, stabbing, throbbing, or aching. The duration of pain, which is constant, va |
https://en.wikipedia.org/wiki/Sverdlovsk%20anthrax%20leak | On 2 April 1979, spores of Bacillus anthracis (the causative agent of anthrax) were accidentally released from a Soviet military research facility in the city of Sverdlovsk, Soviet Union (now Yekaterinburg, Russia). The ensuing outbreak of the disease resulted in the deaths of at least 68 people, although the exact number of victims remains unknown. The cause of the outbreak was denied for years by the Soviet authorities, which blamed the deaths on consumption of tainted meat from the area, and subcutaneous exposure due to butchers handling the tainted meat. The accident was the first major indication in the Western world that the Soviet Union had embarked upon an offensive programme aimed at the development and large-scale production of biological weapons.
Background
Sverdlovsk had been a major production center of the Soviet military-industrial complex since World War II. By the 1970s, 87 per cent of the city's industrial production was military; only 13 per cent for public consumption. It produced tanks, ballistic missiles, rockets and other armaments. The city has at times been referred to as Russia's Pittsburgh because of its large steelmaking industry. During the Cold War, Sverdlovsk became a Soviet "closed city" to which travel was restricted for foreigners.
The biological warfare (BW) facility in Sverdlovsk was built during the period 1947 to 1949 and was a spin-off of the Soviet Union's main military BW facility in Kirov. It was allocated the former site of the Cherkassk-Sverdlovsk Infantry Academy in Sverdlovsk on Ulitsa Zvezdnaya, 1, and abutted the southern industrialised sector of the city. The new facility, known as the USSR Ministry of Defence's Scientific-Research Institute of Hygiene, became operational on 19 July 1949. Alibek suggests that the construction of the institute incorporated technical knowledge which had been extracted from captured Japanese scientists who had participated in the Japanese biological warfare programme. Research was ini |
https://en.wikipedia.org/wiki/Uniface%20%28programming%20language%29 | Uniface is a low-code development and deployment platform for enterprise applications that can run in a large range of runtime environments, including mobile, mainframe, web, Service-oriented architecture (SOA), Windows, Java EE, and .NET. Uniface is used to create mission-critical applications.
Uniface applications are database and platform independent. Uniface provides an integration framework that enables Uniface applications to integrate with all major DBMS products such as Oracle, Microsoft SQL Server, MySQL and IBM Db2. In addition, Uniface also supports file systems such as RMS (HP OpenVMS), Sequential files, operating system text files and a wide range of other technologies, such as IBM mainframe-based products (CICS, IMS), web services, SMTP, POP email, LDAP directories, .NET, ActiveX, Component Object Model (COM), C(++) programs, and Java. Uniface operates under Microsoft Windows, various flavors of Unix, Linux, CentOS and IBM i.
Uniface can be used in complex systems that maintain critical enterprise data supporting mission-critical business processes such as point-of sale and web-based online shopping, financial transactions, salary administration, and inventory control. It is currently used by thousands of companies in more than 30 countries, with an effective installed base of millions of end-users. Uniface applications range from client/server to web, and from data entry to workflow, as well as portals that are accessed locally, via intranets and the internet.
Originally developed in the Netherlands by Inside Automation, later Uniface B.V., the product and company were acquired by Detroit-based Compuware Corp in 1994, and in 2014 was acquired by Marlin Equity Partners and continued as Uniface B.V. global headquartered in Amsterdam. In February 2021 Uniface was acquired by Rocket Software headquartered in Waltham, Massachusetts, USA.
Uniface Products
Uniface Development Environment is an integrated collection of tools for modeling, implementing, |
https://en.wikipedia.org/wiki/Packaging%20gas | A packaging gas is used to pack sensitive materials such as food into a modified atmosphere environment. The gas used is usually inert, or of a nature that protects the integrity of the packaged goods, inhibiting unwanted chemical reactions such as food spoilage or oxidation. Some may also serve as a propellant for aerosol sprays like cans of whipped cream. For packaging food, the use of various gases is approved by regulatory organisations.
Their E numbers are included in the following lists in parentheses.
Inert gases
These gas types do not cause a chemical change to the substance that they protect.
argon (E938), used for canned products
helium (E939), used for canned products
nitrogen (E941), also propellant
carbon dioxide (E290), also propellant
Propellant gases
Specific kinds of packaging gases are aerosol propellants. These process and assist the ejection of the product from its container.
chlorofluorocarbons known as CFC (E940 and E945), now rarely used because of the damage that they do to the ozone layer:
dichlorodifluoromethane (E940)
chloropentafluoroethane (E945)
nitrous oxide (E942), used for aerosol whipped cream canisters (see Nitrous oxide: Aerosol propellant)
octafluorocyclobutane (E946)
Reactive gases
These must be used with caution as they may have adverse effects when exposed to certain chemicals. They will cause oxidisation or contamination to certain types of materials.
oxygen (E948), used e.g. for packaging of vegetables
hydrogen (E949)
Volatile gases
Hydrocarbon gases approved for use with food need to be used with extreme caution as they are highly combustible, when combined with oxygen they burn very rapidly and may cause explosions in confined spaces. Special precautions must be taken when transporting these gases.
butane (E943a)
isobutane (E943b)
propane (E944)
See also
Shielding gas |
https://en.wikipedia.org/wiki/Path%20integration | Path integration is the method thought to be used by animals for dead reckoning.
History
Charles Darwin first postulated an inertially-based navigation system in animals in 1873. Studies beginning in the middle of the 20th century confirmed that animals could return directly to a starting point, such as a nest, in the absence of vision and having taken a circuitous outwards journey. This shows that they can use cues to track distance and direction in order to estimate their position, and hence how to get home. This process was named path integration to capture the concept of continuous integration of movement cues over the journey. Manipulation of inertial cues confirmed that at least one of these movements (or idiothetic) cues are information from the vestibular organs, which detect movement in the three dimensions. Other cues probably include proprioception (information from muscles and joints about limb position), motor efference (information from the motor system telling the rest of the brain what movements were commanded and executed), and optic flow (information from the visual system signaling how fast the visual world is moving past the eyes). Together, these sources of information can tell the animal which direction it is moving, at what speed, and for how long. In addition, sensitivity to the Earth's magnetic field for underground animals (e.g., mole rat) can give path integration.
Mechanism
Studies in arthropods, most notably in the Sahara desert ant (Cataglyphis bicolor), reveal the existence of highly effective path integration mechanisms that depend on determination of directional heading (by polarized light or sun position) and distance computations (by monitoring leg movement or optical flow).
In mammals, three important discoveries shed light on this issue.
The first, in the early 1970s, is that neurons in the hippocampal formation, called place cells, respond to the position of the animal.
The second, in the early 1990s, is that neurons i |
https://en.wikipedia.org/wiki/Tears%20of%20wine | The phenomenon called tears of wine is manifested as a ring of clear liquid, near the top of a glass of wine, from which droplets continuously form and drop back into the wine. It is most readily observed in a wine which has a high alcohol content. It is also referred to as wine legs, fingers, curtains, church windows, or feet.
Cause
The effect is a consequence of the fact that alcohol has a lower surface tension than water. If alcohol is mixed with water inhomogeneously, a region with a lower concentration of alcohol will pull on the surrounding fluid more strongly than a region with a higher alcohol concentration. The result is that the liquid tends to flow away from regions with higher alcohol concentration. This can be easily and strikingly demonstrated by spreading a thin film of water on a smooth surface and then allowing a drop of alcohol to fall on the center of the film. The liquid will rush out of the region where the drop of alcohol fell.
Wine is mostly a mixture of alcohol and water, with dissolved sugars, acids, colourants and flavourants. Where the surface of the wine meets the side of the glass, capillary action makes the liquid climb the side of the glass. As it does so, both alcohol and water evaporate from the rising film, but the alcohol evaporates faster, due to its higher vapor pressure. The resulting decrease in the concentration of alcohol causes the surface tension of the liquid to increase, and this causes more liquid to be drawn up from the bulk of the wine, which has a lower surface tension because of its higher alcohol content. The wine moves up the side of the glass and forms droplets that fall back under their own weight.
The phenomenon was first correctly explained by physicist James Thomson, the elder brother of Lord Kelvin, in 1855. It is an instance of what is today called the Marangoni effect (or the Gibbs-Marangoni effect): the flow of liquid caused by surface tension gradients.
The evaporation of alcohol also creates a |
https://en.wikipedia.org/wiki/Hysteresivity | Hysteresivity derives from “hysteresis”, meaning “lag”. It is the tendency to react slowly to an outside force, or to not return completely to its original state. Whereas the area within a hysteresis loop represents energy dissipated to heat and is an extensive quantity with units of energy, the hysteresivity represents the fraction of the elastic energy that is lost to heat, and is an intensive property that is dimensionless.
Overview
When a force deforms a material it generates elastic stresses and internal frictional stresses. Most often, frictional stress is described as being analogous to the stress that results from the flow of a viscous fluid, but in many engineering materials, in soft biological tissues, and in living cells, the concept that friction arises only from a viscous stress is now known to be erroneous. For example, Bayliss and Robertson
and Hildebrandt demonstrated that frictional stress in lung tissue is dependent upon the amount of lung expansion but not the rate of expansion, findings that are fundamentally incompatible with the notion of friction being caused by a viscous stress. If not by a viscous stress, how then does friction arise, and how is it properly described?
In many inert and living materials, the relationship between elastic and frictional stresses turns out to be very nearly invariant (something unaltered by a transformation). In lung tissues, for example, the frictional stress is almost invariably between 0.1 and 0.2 of the elastic stress, where this fraction is called the hysteresivity, h, or, equivalently, the structural damping coefficient. It is a simple phenomenological fact, therefore, that for each unit of peak elastic strain energy that is stored during a cyclic deformation, 10 to 20% of that elastic energy is taxed as friction and lost irreversibly to heat. This fixed relationship holds at the level of the whole lung
, isolated lung parenchymal tissue strips, isolated smooth muscle strips, and even isolate |
https://en.wikipedia.org/wiki/Sequestrant | A sequestrant is a food additive which improves the quality and stability of foods. A sequestrant forms chelate complexes with polyvalent metal ions, especially copper, iron and nickel. This can prevent the oxidation of the fats in the food. Sequestrants are therefore a type of preservative.
The name comes from Latin and means "to withdraw from use" .
Common sequestrants are:
Calcium chloride (E509)
Calcium acetate (E263)
Calcium disodium ethylene diamine tetra-acetate (E385)
Glucono delta-lactone (E575)
Sodium gluconate (E576)
Potassium gluconate (E577)
Sodium tripolyphosphate (E451)
Sodium hexametaphosphate (E452i)
Sodium and calcium salts of EDTA are also commonly used in many foods and beverages. |
https://en.wikipedia.org/wiki/Doubly%20stochastic%20matrix | In mathematics, especially in probability and combinatorics, a doubly stochastic matrix
(also called bistochastic matrix) is a square matrix of nonnegative real numbers, each of whose rows and columns sums to 1, i.e.,
Thus, a doubly stochastic matrix is both left stochastic and right stochastic.
Indeed, any matrix that is both left and right stochastic must be square: if every row sums to 1 then the sum of all entries in the matrix must be equal to the number of rows, and since the same holds for columns, the number of rows and columns must be equal.
Birkhoff polytope
The class of doubly stochastic matrices is a convex polytope known as the Birkhoff polytope . Using the matrix entries as Cartesian coordinates, it lies in an -dimensional affine subspace of -dimensional Euclidean space defined by independent linear constraints specifying that the row and column sums all equal 1. (There are constraints rather than because one of these constraints is dependent, as the sum of the row sums must equal the sum of the column sums.) Moreover, the entries are all constrained to be non-negative and less than or equal to 1.
Birkhoff–von Neumann theorem
The Birkhoff–von Neumann theorem (often known simply as Birkhoff's theorem) states that the polytope is the convex hull of the set of permutation matrices, and furthermore that the vertices of are precisely the permutation matrices. In other words, if is a doubly stochastic matrix, then there exist and permutation matrices such that
(Such a decomposition of X is known as a 'convex combination'.) A proof of the theorem based on Hall's marriage theorem is given below.
This representation is known as the Birkhoff–von Neumann decomposition, and may not be unique. It is often described as a real-valued generalization of Kőnig's theorem, where the correspondence is established through adjacency matrices of graphs.
Other properties
The product of two doubly stochastic matrices is doubly stochastic. However, the |
https://en.wikipedia.org/wiki/Acidity%20regulator | Acidity regulators, or pH control agents, are food additives used to change or maintain pH (acidity or basicity). They can be organic or mineral acids, bases, neutralizing agents, or buffering agents. Typical agents include the following acids and their sodium salts: sorbic acid, acetic acid, benzoic acid, and propionic acid. Acidity regulators are indicated by their E number, such as E260 (acetic acid), or simply listed as "food acid".
Acidity regulators differ from acidulants, which are often acidic but are added to confer sour flavors. They are not intended to stabilize the food, although that can be a collateral benefit. Acidity regulators are also important for food safety, as incorrect pH can result in bacteria growth.
See also
Adipic acid
List of food additives
Sodium bicarbonate |
https://en.wikipedia.org/wiki/Firming%20agent | Firming agents are food additives added in order to precipitate residual pectin, thus strengthening the structure of the food and preventing its collapse during processing.
These are salts, typically lactates or phosphates, calcium salts or aluminum sulfates.
They are mainly used for (fresh) fruit and vegetables. For example, in the case of fruit sold cut into wedges, the pulp can be sprayed with a solution of the respective salt. They are salts that react with an ingredient in the product, such as the pectin in the fruit.
Typical firming agents are:
Calcium carbonate (E170)
Calcium hydrogen sulfite (E227)
Calcium citrates (E333)
Calcium phosphates (E341)
Calcium sulfate (E516)
Calcium chloride (E509)
Magnesium chloride (E511)
Magnesium sulfate (E518)
Calcium gluconate (E578)
Magnesium gluconate (E580) |
https://en.wikipedia.org/wiki/Calorescence | Calorescence is a term describing the process whereby matter absorbs infrared radiant energy and emits visible radiant energy in its place. For example, some kinds of flammable gas give off large amounts of radiant heat and very little visible light when burning, and if a piece of metal is placed into such a flame, the metal will become bright red-hot—which is to say the metal absorbs invisible infrared and emits visible radiation. The word calorescence was coined by John Tyndall in 1864 on the model of the word fluorescence which had been coined in 1852. At that time, fluorescence was defined as absorption in the ultraviolet part of the spectrum followed by emission in the visible part of the spectrum. Calorescence was defined complementarily as absorption in the infrared followed by emission in the visible. Earlier, George Stokes had shown the reverse phenomenon: the emission of infrared following the absorption of visible light.
The following is a laboratory demonstration of calorescence. An ordinary lightbulb emits much infrared light. Carbon disulfide is a colorless liquid transparent to both infrared and visible. Iodine readily dissolves in this liquid and causes the liquid to turn a black color and to become completely opaque to visible light, given enough iodine. At the same time, however, the iodine has essentially no effect on the transparency of the liquid with respect to infrared light. Hence when light from an ordinary lightbulb is passed through a body of this solution, much infrared and only infrared emerges out at the other side. This infrared light can be brought to a focus with a concave mirror (or an optical lens made from rock-salt, but not a lens made from glass because glass is a poor transmitter of infrared). At the point of focus, with a good focusing tool, the infrared beam is strong enough to set paper on fire. If a little piece of non-combustible solid material is placed at the focus, it will glow visibly in the heat; i.e. the material w |
https://en.wikipedia.org/wiki/Edubuntu | Edubuntu, previously known as Ubuntu Education Edition, is an official derivative of the Ubuntu operating system designed for use in classrooms inside schools, homes and communities.
Edubuntu is developed in collaboration with teachers and technologists in several countries. Edubuntu is built on top of the Ubuntu base, incorporates the LTSP thin client architecture and several education-specific applications, and is aimed at users aged 6 to 18. It was designed for easy installation and ongoing system maintenance.
Features
Included with Edubuntu is the Linux Terminal Server Project and many applications relevant to education including GCompris, KDE Edutainment Suite, Sabayon Profile Manager, Pessulus Lockdown Editor, Edubuntu Menueditor, LibreOffice, Gnome Nanny and iTalc. Edubuntu CDs were previously available free of charge through their Shipit service; it is only available as a download in a DVD format.
In 23.04, Edubuntu's default GUI is GNOME. From 12.04 to 14.04, Edubuntu's default GUI was Unity; however GNOME, which had previously been the default, was also available. Since release 7.10, KDE is also available as Edubuntu KDE. In 2010, Edubuntu and the Qimo 4 Kids project were working on providing Qimo within Edubuntu, but this was not done as it would not have fit on a CD.
Project goals
The primary goal of Edubuntu was to enable an educator with limited technical knowledge and skills to set up a computer lab or an on-line learning environment in an hour or less and then effectively administer that environment.
The principal design goals of Edubuntu were centralized management of configuration, users and processes, together with facilities for working collaboratively in a classroom setting. Equally important was the gathering together of the best available free software and digital materials for education. According to a statement of goals on the official Edubuntu website: "Our aim is to put together a system that contains all the best free software ava |
https://en.wikipedia.org/wiki/Cystolith | Cystolith (Gr. "cavity" and "stone") is a botanical term for outgrowths of the epidermal cell wall, usually of calcium carbonate, formed in a cellulose matrix in special cells called lithocysts, generally in the leaf of plants.
Cystoliths are present in certain families, including in many genera of Acanthaceae. Plants in the family Urticaceae, known as stinging nettles, also form leaf cystoliths, but only during their later flowering and seed setting stages. Other examples include Cannabis and other plants in the family Cannabaceae, which produce leaf and flower cystoliths, and Ficus elastica, the Indian rubber plant of the family Moraceae.
From a 1987 article on cystolith development and structure: |
https://en.wikipedia.org/wiki/Dorsiventral | A dorsiventral (Lat. dorsum, "the back", venter, "the belly") organ is one that has two surfaces differing from each other in appearance and structure, as an ordinary leaf. This term has also been used as a synonym for dorsoventral organs, those that extend from a dorsal to a ventral surface.
This word is also used to define body structure of an organism, e.g. flatworm have dorsiventrally flattened bodies. |
https://en.wikipedia.org/wiki/Strobogrammatic%20number | A strobogrammatic number is a number whose numeral is rotationally symmetric, so that it appears the same when rotated 180 degrees. In other words, the numeral looks the same right-side up and upside down (e.g., 69, 96, 1001). A strobogrammatic prime is a strobogrammatic number that is also a prime number, i.e., a number that is only divisible by one and itself (e.g., 11). It is a type of ambigram, words and numbers that retain their meaning when viewed from a different perspective, such as palindromes.
Description
When written using standard characters (ASCII), the numbers, 0, 1, 8 are symmetrical around the horizontal axis, and 6 and 9 are the same as each other when rotated 180 degrees. In such a system, the first few strobogrammatic numbers are:
0, 1, 8, 11, 69, 88, 96, 101, 111, 181, 609, 619, 689, 808, 818, 888, 906, 916, 986, 1001, 1111, 1691, 1881, 1961, 6009, 6119, 6699, 6889, 6969, 8008, 8118, 8698, 8888, 8968, 9006, 9116, 9696, 9886, 9966, ...
The first few strobogrammatic primes are:
11, 101, 181, 619, 16091, 18181, 19861, 61819, 116911, 119611, 160091, 169691, 191161, 196961, 686989, 688889, ...
The years 1881 and 1961 were the most recent strobogrammatic years; the next strobogrammatic year will be 6009.
Although amateur aficionados of mathematics are quite interested in this concept, professional mathematicians generally are not. Like the concept of repunits and palindromic numbers, the concept of strobogrammatic numbers is base-dependent (expanding to base-sixteen, for example, produces the additional symmetries of 3/E; some variants of duodecimal systems also have this and a symmetrical x). Unlike palindromes, it is also font dependent. The concept of strobogrammatic numbers is not neatly expressible algebraically, the way that the concept of repunits is, or even the concept of palindromic numbers.
Nonstandard systems
The strobogrammatic properties of a given number vary by typeface. For instance, in an ornate serif type, the numbers 2 and 7 |
https://en.wikipedia.org/wiki/Kurosh%20problem | In mathematics, the Kurosh problem is one general problem, and several more special questions, in ring theory. The general problem is known to have a negative solution, since one of the special cases has been shown to have counterexamples. These matters were brought up by Aleksandr Gennadievich Kurosh as analogues of the Burnside problem in group theory.
Kurosh asked whether there can be a finitely-generated infinite-dimensional algebraic algebra (the problem being to show this cannot happen). A special case is whether or not every nil algebra is locally nilpotent.
For PI-algebras the Kurosh problem has a positive solution.
Golod showed a counterexample to that case, as an application of the Golod–Shafarevich theorem.
The Kurosh problem on group algebras concerns the augmentation ideal I. If I is a nil ideal, is the group algebra locally nilpotent?
There is an important problem which is often referred as the Kurosh's problem on division rings. The problem asks whether there exists an algebraic (over the center) division ring which is not locally finite. This problem has not been solved until now. |
https://en.wikipedia.org/wiki/Pencil%20%28geometry%29 | In geometry, a pencil is a family of geometric objects with a common property, for example the set of lines that pass through a given point in a plane, or the set of circles that pass through two given points in a plane.
Although the definition of a pencil is rather vague, the common characteristic is that the pencil is completely determined by any two of its members. Analogously, a set of geometric objects that are determined by any three of its members is called a bundle. Thus, the set of all lines through a point in three-space is a bundle of lines, any two of which determine a pencil of lines. To emphasize the two-dimensional nature of such a pencil, it is sometimes referred to as a flat pencil.
Any geometric object can be used in a pencil. The common ones are lines, planes, circles, conics, spheres, and general curves. Even points can be used. A pencil of points is the set of all points on a given line. A more common term for this set is a range of points.
Pencil of lines
In a plane, let and be two distinct intersecting lines. For concreteness, suppose that has the equation, and has the equation . Then
,
represents, for suitable scalars and , any line passing through the intersection of = 0 and = 0. This set of lines passing through a common point is called a pencil of lines. The common point of a pencil of lines is called the vertex of the pencil.
In an affine plane with the reflexive variant of parallelism, a set of parallel lines forms an equivalence class called a pencil of parallel lines. This terminology is consistent with the above definition since in the unique projective extension of the affine plane to a projective plane a single point (point at infinity) is added to each line in the pencil of parallel lines, thus making it a pencil in the above sense in the projective plane.
Pencil of planes
A pencil of planes, is the set of planes through a given straight line in three-space, called the axis of the pencil. The pencil is sometimes refer |
https://en.wikipedia.org/wiki/Signed%20zero | Signed zero is zero with an associated sign. In ordinary arithmetic, the number 0 does not have a sign, so that −0, +0 and 0 are equivalent. However, in computing, some number representations allow for the existence of two zeros, often denoted by −0 (negative zero) and +0 (positive zero), regarded as equal by the numerical comparison operations but with possible different behaviors in particular operations. This occurs in the sign-magnitude and ones' complement signed number representations for integers, and in most floating-point number representations. The number 0 is usually encoded as +0, but can still be represented by +0, −0, or 0.
The IEEE 754 standard for floating-point arithmetic (presently used by most computers and programming languages that support floating-point numbers) requires both +0 and −0. Real arithmetic with signed zeros can be considered a variant of the extended real number line such that 1/−0 = −∞ and 1/+0 = +∞; division is only undefined for ±0/±0 and ±∞/±∞.
Negatively signed zero echoes the mathematical analysis concept of approaching 0 from below as a one-sided limit, which may be denoted by x → 0−, x → 0−, or x → ↑0. The notation "−0" may be used informally to denote a negative number that has been rounded to zero. The concept of negative zero also has some theoretical applications in statistical mechanics and other disciplines.
It is claimed that the inclusion of signed zero in IEEE 754 makes it much easier to achieve numerical accuracy in some critical problems, in particular when computing with complex elementary functions. On the other hand, the concept of signed zero runs contrary to the usual assumption made in mathematics that negative zero is the same value as zero. Representations that allow negative zero can be a source of errors in programs, if software developers do not take into account that while the two zero representations behave as equal under numeric comparisons, they yield different results in some operations.
Re |
https://en.wikipedia.org/wiki/Gloger%27s%20rule | Gloger's rule is an ecogeographical rule which states that within a species of endotherms, more heavily pigmented forms tend to be found in more humid environments, e.g. near the equator. It was named after the zoologist Constantin Wilhelm Lambert Gloger, who first remarked upon this phenomenon in 1833 in a review of covariation of climate and avian plumage color. Erwin Stresemann later noted that the idea had been expressed even earlier by Peter Simon Pallas in Zoographia Rosso-Asiatica (1811). Gloger found that birds in more humid habitats tended to be darker than their relatives from regions with higher aridity. Over 90% of 52 North American bird species studies conform to this rule.
One explanation of Gloger's rule in the case of birds appears to be the increased resistance of dark feathers to feather- or hair-degrading bacteria such as Bacillus licheniformis. Feathers in humid environments have a greater bacterial load, and humid environments are more suitable for microbial growth; dark feathers or hair are more difficult to break down. More resilient eumelanins (dark brown to black) are deposited in hot and humid regions, whereas in arid regions, pheomelanins (reddish to sandy color) predominate due to the benefit of crypsis.
Among mammals, there is a marked tendency in equatorial and tropical regions to have a darker skin color than poleward relatives. In this case, the underlying cause is probably the need to better protect against the more intense solar UV radiation at lower latitudes. However, absorption of a certain amount of UV radiation is necessary for the production of certain vitamins, notably vitamin D (see also osteomalacia).
Gloger's rule is also vividly demonstrated among human populations. Populations that evolved in sunnier environments closer to the equator tend to be darker-pigmented than populations originating farther from the equator. There are exceptions, however; among the most well known are the Tibetans and Inuit, who have darker s |
https://en.wikipedia.org/wiki/Agarophyte | An agarophyte is a seaweed, usually a red alga, that produces the hydrocolloid agar in its cell walls. This agar can be harvested commercially for use in biological experiments and culturing. In some countries (especially in the developing world), the harvesting of agarophytes, either as natural stocks or a cultivated crop, is of considerable economic importance. Notable genera of commercially exploited agarophytes include Gracilaria and Gelidium (such as Gelidium amansii and Gelidium corneum). |
https://en.wikipedia.org/wiki/Gracilaria | Gracilaria is a genus of red algae (Rhodophyta) notable for its economic importance as an agarophyte, as well as its use as a food for humans and various species of shellfish. Various species in the genus are cultivated among Asia, South America, Africa and Oceania.
Taxonomy
Gracilaria contains the following subtaxa:
Gracilaria abbottiana M.D.Hoyle
Gracilaria abyssalis Gurgel & Yoneshigue-Valentin
Gracilaria aculeata (Hering) Papenfuss
Gracilaria aggregata Hooker f. & Harvey
Gracilaria ambigua Greville
Gracilaria apiculata P.Crouan & H.Crouan
Gracilaria apiculata subsp. candelabriformis Gurgel, Fredericq & J.N.Norris
Gracilaria apiculifera J.Agardh
Gracilaria arcuata f. rhizophora Børgesen
Gracilaria arcuata var. attenuata Umamaheswara Rao
Gracilaria arcuata var. snackeyi Weber Bosse
Gracilaria arcuata Zanardini
Gracilaria armata (C.Agardh) Greville
Gracilaria articulata C.F.Chang & B.M.Xia
Gracilaria ascidiicola E.Y.Dawson
Gracilaria attenuata (M.Umamaheswara Rao) V.Krishnamurthy
Gracilaria austromaritima Przhemenstskaya
Gracilaria babae (H.Yamamoto) P.-K. Ng, P.-E. Lim & S.-M. Phang
Gracilaria baiana Lyra, Gurgel, M.C.Oliveira & Nunes
Gracilaria beckeri (J.Agardh) Papenfuss
Gracilaria birdiae E.M.Plastino & E.C.Oliveira
Gracilaria blodgettii Harvey
Gracilaria brasiliensis Gurgel & Yoneshigue-Valentin
Gracilaria brevis W.R.Taylor
Gracilaria bursa-pastoris (S.G.Gmelin) P.C.Silva
Gracilaria camerunensis Pilger
Gracilaria canaliculata Sonder
Gracilaria capensis F.Schmitz ex Mazza
Gracilaria capitata Zanardini
Gracilaria cearensis (A.B.Joly & Pinheiro) A.B.Joly & Pinheiro
Gracilaria cerrosiana W.R.Taylor
Gracilaria cervicornis (Turner) J.Agardh
Gracilaria changii (B.M.Xia & I.A.Abbott) I.A.Abbott, J.Zhang & B.M.Xia
Gracilaria chilensis C.J.Bird, McLachlan & E.C.Oliveira
Gracilaria chondracantha (Kützing) A.J.K.Millar
Gracilaria chondroides (Kützing) P.Crouan & H.Crouan
Gracilaria chorda var. exilis Yamamoto
Gracilaria chouae Zhang & B.M.Xia
Gracilaria cliftonii Withe |
https://en.wikipedia.org/wiki/Membranelle | Membranelles (also membranellae) are structures found around the mouth, or cytostome, in ciliates. They are typically arranged in series, to form an "adoral zone of membranelles", or AZM, on the left side of the buccal cavity (peristome). The membranelles are made up of kinetosomes arranged in groups to make up polykinetids. The cilia which emerge from these structures appear to be fused and to function as a single membrane, which can be used to sweep particles of food into the cytostome, or for locomotion. |
https://en.wikipedia.org/wiki/Gamma%20matrices | In mathematical physics, the gamma matrices, also called the Dirac matrices, are a set of conventional matrices with specific anticommutation relations that ensure they generate a matrix representation of the Clifford algebra It is also possible to define higher-dimensional gamma matrices. When interpreted as the matrices of the action of a set of orthogonal basis vectors for contravariant vectors in Minkowski space, the column vectors on which the matrices act become a space of spinors, on which the Clifford algebra of spacetime acts. This in turn makes it possible to represent infinitesimal spatial rotations and Lorentz boosts. Spinors facilitate spacetime computations in general, and in particular are fundamental to the Dirac equation for relativistic particles.
In Dirac representation, the four contravariant gamma matrices are
is the time-like, Hermitian matrix. The other three are space-like, anti-Hermitian matrices. More compactly, and where denotes the Kronecker product and the (for ) denote the Pauli matrices.
In addition, for discussions of group theory the identity matrix () is sometimes included with the four gamma matricies, and there is an auxiliary, "fifth" traceless matrix used in conjunction with the regular gamma matrixies
The "fifth matrix" is not a proper member of the main set of four; it used for separating nominal left and right chiral representations.
The gamma matrices have a group structure, the gamma group, that is shared by all matrix representations of the group, in any dimension, for any signature of the metric. For example, the 2×2 Pauli matrices are a set of "gamma" matrices in three dimensional space with metric of Euclidean signature (3, 0). In five spacetime dimensions, the four gammas, above, together with the fifth gamma-matrix to be presented below generate the Clifford algebra.
Mathematical structure
The defining property for the gamma matrices to generate a Clifford algebra is the anticommutation relation
wher |
https://en.wikipedia.org/wiki/Behrens%E2%80%93Fisher%20problem | In statistics, the Behrens–Fisher problem, named after Walter-Ulrich Behrens and Ronald Fisher, is the problem of interval estimation and hypothesis testing concerning the difference between the means of two normally distributed populations when the variances of the two populations are not assumed to be equal, based on two independent samples.
Specification
One difficulty with discussing the Behrens–Fisher problem and proposed solutions, is that there are many different interpretations of what is meant by "the Behrens–Fisher problem". These differences involve not only what is counted as being a relevant solution, but even the basic statement of the context being considered.
Context
Let X1, ..., Xn and Y1, ..., Ym be i.i.d. samples from two populations which both come from the same location–scale family of distributions. The scale parameters are assumed to be unknown and not necessarily equal, and the problem is to assess whether the location parameters can reasonably be treated as equal. Lehmann states that "the Behrens–Fisher problem" is used both for this general form of model when the family of distributions is arbitrary, and for when the restriction to a normal distribution is made. While Lehmann discusses a number of approaches to the more general problem, mainly based on nonparametrics, most other sources appear to use "the Behrens–Fisher problem" to refer only to the case where the distribution is assumed to be normal: most of this article makes this assumption.
Requirements of solutions
Solutions to the Behrens–Fisher problem have been presented that make use of either a classical or a Bayesian inference point of view and either solution would be notionally invalid judged from the other point of view. If consideration is restricted to classical statistical inference only, it is possible to seek solutions to the inference problem that are simple to apply in a practical sense, giving preference to this simplicity over any inaccuracy in the corresponding |
https://en.wikipedia.org/wiki/Cyclic%20enzyme%20system | A cyclic enzyme system is a theoretical system of two enzymes sharing a single substrate or cofactor, also referred to as a biochemical switching device. It has been used as a biochemical implementation of a simple computational device, acting as a chemical diode.
See also
Biocomputer
Computational gene |
https://en.wikipedia.org/wiki/Studentization | In statistics, Studentization, named after William Sealy Gosset, who wrote under the pseudonym Student, is the adjustment consisting of division of a first-degree statistic derived from a sample, by a sample-based estimate of a population standard deviation. The term is also used for the standardisation of a higher-degree statistic by another statistic of the same degree: for example, an estimate of the third central moment would be standardised by dividing by the cube of the sample standard deviation.
A simple example is the process of dividing a sample mean by the sample standard deviation when data arise from a location-scale family. The consequence of "Studentization" is that the complication of treating the probability distribution of the mean, which depends on both the location and scale parameters, has been reduced to considering a distribution which depends only on the location parameter. However, the fact that a sample standard deviation is used, rather than the unknown population standard deviation, complicates the mathematics of finding the probability distribution of a Studentized statistic.
In computational statistics, the idea of using Studentized statistics is of some importance in the development of confidence intervals with improved properties in the context of resampling and, in particular, bootstrapping.
Examples
Studentized range
Studentized residual
See also
Pivotal quantity |
https://en.wikipedia.org/wiki/Podophyllotoxin | Podophyllotoxin (PPT) is the active ingredient in Podofilox, which is a medical cream that is used to treat genital warts and molluscum contagiosum. It is not recommended in HPV infections without external warts. It can be applied either by a healthcare provider or the person themselves.
It is a non-alkaloid toxin lignin extracted from the roots and rhizomes of Podophyllum species. A less refined form known as podophyllum resin is also available, but has greater side effects.
Podophyllotoxin was first isolated in pure form in 1880 by Valerian Podwyssotzki (1818 – 28 January 1892), a Polish-Russian privatdozent at the University of Dorpat (now: Tartu, Estonia) and assistant at the Pharmacological Institute there.
It is on the World Health Organization's List of Essential Medicines.
Medical uses
Podophyllotoxin possesses a large number of medical applications, as it is able to stop replication of both cellular and viral DNA by binding necessary enzymes. It can additionally destabilize microtubules and prevent cell division. Because of these interactions it is considered an antimitotic drug, although modern medicine instead use less orally toxic derivatives when such effect is wanted.
Podophyllotoxin cream is commonly prescribed as a potent topical antiviral. It is used for the treatment of HPV infections with external warts as well as molluscum contagisum infections. 0.5% PPT cream is prescribed for twice daily applications for 3 days followed by 4 days with no application, this weekly cycle is repeated for 4 weeks. It can also be prescribed as a gel, as opposed to cream. PPT is also sold under the names condyline and warticon.
Adverse effects
The most common side effects of podophyllotoxin cream are typically limited to irritation of tissue surrounding the application site, including burning, redness, pain, itching, swelling. Application can be immediately followed by burning or itching. Small sores, itching and peeling skin can also follow, for these reasons |
https://en.wikipedia.org/wiki/Klein%20geometry | In mathematics, a Klein geometry is a type of geometry motivated by Felix Klein in his influential Erlangen program. More specifically, it is a homogeneous space X together with a transitive action on X by a Lie group G, which acts as the symmetry group of the geometry.
For background and motivation see the article on the Erlangen program.
Formal definition
A Klein geometry is a pair where G is a Lie group and H is a closed Lie subgroup of G such that the (left) coset space G/H is connected. The group G is called the principal group of the geometry and G/H is called the space of the geometry (or, by an abuse of terminology, simply the Klein geometry). The space of a Klein geometry is a smooth manifold of dimension
dim X = dim G − dim H.
There is a natural smooth left action of G on X given by
Clearly, this action is transitive (take ), so that one may then regard X as a homogeneous space for the action of G. The stabilizer of the identity coset is precisely the group H.
Given any connected smooth manifold X and a smooth transitive action by a Lie group G on X, we can construct an associated Klein geometry by fixing a basepoint x0 in X and letting H be the stabilizer subgroup of x0 in G. The group H is necessarily a closed subgroup of G and X is naturally diffeomorphic to G/H.
Two Klein geometries and are geometrically isomorphic if there is a Lie group isomorphism so that . In particular, if φ is conjugation by an element , we see that and are isomorphic. The Klein geometry associated to a homogeneous space X is then unique up to isomorphism (i.e. it is independent of the chosen basepoint x0).
Bundle description
Given a Lie group G and closed subgroup H, there is natural right action of H on G given by right multiplication. This action is both free and proper. The orbits are simply the left cosets of H in G. One concludes that G has the structure of a smooth principal H-bundle over the left coset space G/H:
Types of Klein geometries
Effective geo |
https://en.wikipedia.org/wiki/Serre%27s%20modularity%20conjecture | In mathematics, Serre's modularity conjecture, introduced by , states that an odd, irreducible, two-dimensional Galois representation over a finite field arises from a modular form. A stronger version of this conjecture specifies the weight and level of the modular form. The conjecture in the level 1 case was proved by Chandrashekhar Khare in 2005, and a proof of the full conjecture was completed jointly by Khare and Jean-Pierre Wintenberger in 2008.
Formulation
The conjecture concerns the absolute Galois group of the rational number field .
Let be an absolutely irreducible, continuous, two-dimensional representation of over a finite field .
Additionally, assume is odd, meaning the image of complex conjugation has determinant -1.
To any normalized modular eigenform
of level , weight , and some Nebentype character
,
a theorem due to Shimura, Deligne, and Serre-Deligne attaches to a representation
where is the ring of integers in a finite extension of . This representation is characterized by the condition that for all prime numbers , coprime to we have
and
Reducing this representation modulo the maximal ideal of gives a mod representation of .
Serre's conjecture asserts that for any representation as above, there is a modular eigenform such that
.
The level and weight of the conjectural form are explicitly conjectured in Serre's article. In addition, he derives a number of results from this conjecture, among them Fermat's Last Theorem and the now-proven Taniyama–Weil (or Taniyama–Shimura) conjecture, now known as the modularity theorem (although this implies Fermat's Last Theorem, Serre proves it directly from his conjecture).
Optimal level and weight
The strong form of Serre's conjecture describes the level and weight of the modular form.
The optimal level is the Artin conductor of the representation, with the power of removed.
Proof
A proof of the level 1 and small weight cases of the conjecture was obtained in 2004 by Chandrashekha |
https://en.wikipedia.org/wiki/Chemical%20clock | A chemical clock (or clock reaction) is a complex mixture of reacting chemical compounds in which the onset of an observable property (discoloration or coloration) occurs after a predictable induction time due to the presence of clock species at a detectable amount.
In cases where one of the reagents has a visible color, crossing a concentration threshold can lead to an abrupt color change after a reproducible time lapse.
Types
Clock reactions may be classified into three or four types:
Substrate-depletive clock reaction
The simplest clock reaction featuring two reactions:
A → C (rate k1)
B + C → products (rate k2, fast)
When substrate (B) is present, the clock species (C) is quickly consumed in the second reaction. Only when substrate B is all used up or depleted, species C can build up in amount causing the color to change. An example for this clock reaction is the sulfite/iodate reaction or iodine clock reaction, also known as Landolt's reaction.
Sometimes, a clock reaction involves the production of intermediate species in three consecutive reactions.
P + Q → R
R + Q → C
P + C → 2R
Given that Q is in excess, when substrate (P) is depleted, C builds up resulting in the change in color.
Autocatalysis-driven clock reaction
The basis of the reaction is similar to substrate-depletive clock reaction, except for the fact that rate k2 is very slow leading to the co-existing of substrates and clock species, so there is no need for substrate to be depleted to observe the change in color. The example for this clock is pentathionate/iodate reaction.
Pseudoclock behavior
The reactions in this category behave like a clock reaction, however they are irreproducible, unpredictable and hard to control. Examples are chlorite/thiosulfate and iodide/chlorite reactions.
Crazy clock reaction
The reaction is irreproducible in each run due to the initial inhomogeneity of the mixture which result from variation in stirring rate, overall volume as well as geometry of |
https://en.wikipedia.org/wiki/Graphical%20Data%20Display%20Manager | GDDM (Graphical Data Display Manager) is a computer graphics system for the IBM System/370 which was developed in IBM's Hursley lab, and first released in 1979. GDDM was originally designed to provide programming support for the IBM 3279 colour display terminal and the associated 3287 colour printer. The 3279 was a colour graphics terminal designed to be used in a general business environment.
GDDM was extended in the early 1980s to provide graphics support for all of IBM's display terminals and printers, and ran on all of IBM's mainframe operating systems.
GDDM also provided support for the (then current) international standards for interactive computer graphics: GKS and PHIGS. Both GKS and PHIGS were designed around the requirements of CAD systems.
GDDM is also available on the IBM i midrange operating system, as well as its predecessor, the AS/400.
GDDM comprises a number of components:
Graphics primitives - lines, circles, boxes etc.
Graphing - through the Presentation Graphics Feature (PGF)
Language support - PL/I, REXX, COBOL etc.
Conversion capabilities - for example to GIF format.
Interactive Chart Utility (ICU).
GDDM remains in widespread use today, embedded in many z/OS applications, as well as in system programs.
GDDM and OS/2 Presentation Manager
IBM and Microsoft began collaborating on the design of OS/2 in 1986. The Graphics Presentation Interface (GPI), the graphics API in the OS/2 Presentation Manager, was based on IBM's GDDM and the Graphics Control Program (GCP). GCP was originally developed in Hursley for the 3270/PC-G and 3270/PC-GX terminals.
The GPI was the primary graphics API for the OS/2 operating system.
At the time (1980s), the graphical user interface (GUI) was still in its early stages of popularity, but already it was clear that the foundation of a good GUI was a graphics API with strong real-time interactive capabilities. Unfortunately, the design of GDDM was closer to (at the time) traditional graphics APIs like GKS, wh |
https://en.wikipedia.org/wiki/General%20Service%20Code | General Service Code is a code that was used during the American Civil War. The code uses one flag or two torches.
The flags come in three color schemes: a red square in the middle of a white background, white on black, or black on white. The flag that is used at any time depends on the visibility.
The flags come in three sizes: two feet by two feet, four by four, and six by six. The 2x2 flags are used in battle to send messages back to headquarters and to send back commands, sometimes by more than one signaler. The 4x4 flags are used for almost everything else. The 6x6 flags are for sending messages that can't wait until night so they could use the torches. These flags are so heavy that no one really wanted to use them.
One torch is put on a pole and waved around and is called the action torch. The other was stuck on a stake and called the foot torch. The purpose of the foot torch is to decipher if the message is meant for you or for the guy on the other side of the sender.
The torches run on turpentine. Turpentine is used in the torches because it burns brighter than kerosene. People don't use turpentine in lamps because it is far too volatile to be used in that manner.
The code uses three positions. Position one is to the left. Position two is to the right. Position three is forward. The following is the code and shortcuts.
A 11 B 1221 C 212 D 111 E 21 F 1112 G 1122 H 211 I 2 J 2211
K 1212 L 112 M 2112 N 22 O 12 P 2121 Q 2122 R 122 S 121 T 1
U 221 V 2111 W 2212 X 1211 Y 222 Z 1111
1 12221 2 21112 3 11211 4 11121 5 11112 6 21111 7 22111 8 22221 9 22122 0 11111
& 2222 -tion 2221 -ing 1121 -ed 1222
121212 Error
3 End of word
33 End of sentence
333 End of message
11, 11, 11, 3 Message received or understood
11, 11, 11, 333 Cease signaling
1 Wait a moment. 2 Are you ready? 3 I am ready.
4 Use short pole and small f |
https://en.wikipedia.org/wiki/Natural%20gum | Natural gums are polysaccharides of natural origin, capable of causing a large increase in a solution's viscosity, even at small concentrations. They are mostly botanical gums, found in the woody elements of plants or in seed coatings.
Human uses
Gums are used in the food industry as thickening agents, gelling agents, emulsifying agents, and stabilizers, and in other industrial adhesives, binding agents, crystal inhibitors, clarifying agents, encapsulating agents, flocculating agents, swelling agents, foam stabilizers, etc. When consumed by humans, many of these gums are fermented by the microbes that inhabit the lower gastrointestinal tract (microbiome) and may influence the ecology and functions of these microscopic communities.
Commercial significance
Humans have used natural gums for various purposes, including chewing and the manufacturing of a wide range of products - such as varnish and lacquerware. Before the invention of synthetic equivalents, trade in gum formed part of the economy in places such as the Arabian peninsula (whence the name "gum arabic"), West Africa,
East Africa (copal) and northern New Zealand (kauri gum).
Examples
Natural gums can be classified according to their origin. They can also be classified as uncharged or ionic polymers (polyelectrolytes). Examples include (with E number food additive code): |
https://en.wikipedia.org/wiki/Glazing%20agent | A glazing agent is a natural or synthetic substance that provides a waxy, homogeneous, coating to prevent water loss from a surface and provide other protection.
Natural
Natural glazing agents keep moisture inside plants and insects. Scientists harnessed this characteristic in coatings made of substances classified as waxes. A natural wax is chemically defined as an ester with a very long hydrocarbon chain that also includes a long chain alcohol.
Examples are:
Stearic acid (E570)
Beeswax (E901)
Candelilla wax (E902)
Carnauba wax (E903)
Shellac (E904)
Microcrystalline wax (E905c), Crystalline wax (E907)
Lanolin (E913)
Oxidized polyethylene wax (E914)
Esters of colophonium (E915)
Paraffin
Synthetic
Scientists have produced glazing agents that mimic their natural counterparts. These components are added in different proportions to achieve the optimal glazing agent for a product. Such products include cosmetics, automobiles and food.
Some of the characteristics that are looked for in all of the above industries are:
1. Preservation - the glazing agent must protect the product from degradation and water loss. This characteristic can lead to a longer shelf life for a food or the longevity of a car without rusting.
2. Stability - the glazing agent must maintain its integrity under pressure or heat.
3. Uniform viscosity - this ensures a stronger protective coating that can be applied to the product as a homogeneous layer.
4. Industrial reproduction - because most glazing agents are used on commercial goods and therefore large quantities of glazing agent may be needed.
There are different variations of glazing agents, depending on the product, but they are all designed for the same purpose. |
https://en.wikipedia.org/wiki/Upjohn | The Upjohn Company was a pharmaceutical manufacturing firm founded in 1886 in Hastings, Michigan, by Dr. William E. Upjohn who was an 1875 graduate of the University of Michigan medical school. The company was originally formed to make friable pills, which were specifically designed to be easily digested. They could be "reduced to a powder under the thumb", a strong marketing argument at the time.
History
Upjohn developed a process for the large scale production of cortisone. The oxygen atom at the 11 position in this steroid is an absolute requirement for biological activity. There are however no known natural sources for starting materials that contain that feature. The only method for preparing this drug prior to 1952 was a lengthy synthesis starting from cholic acid isolated from bile. In 1952, two Upjohn biochemists, Dury Peterson and Herb Murray announced that they were able to introduce this crucial oxygen atom by fermentation of the steroid progesterone with a common mold of the genus Rhizopus. Over the next several years a group of chemists headed by John Hogg developed a process for preparing cortisone from the soybean sterol stigmasterol. The microbiological oxygenation is a key step in this process.
Subsequently, Upjohn together with Schering biochemically converted cortisone into the more potent steroid prednisone by a bacterial fermentation. In chemical research, the company is known for the development of the Upjohn dihydroxylation by V. VanRheenen, R. C. Kelly, and D. Y. Cha in 1976. Upjohn's best known drugs before the acquisition by Pfizer were Xanax, Halcion, Motrin, Lincocin, and Rogaine.
In 1995, Upjohn merged with Pharmacia AB to form Pharmacia & Upjohn; the company was owned by Pfizer from 2002 until 2020.
In 2015, Pfizer resurrected the Upjohn name for a division which manufactures and licenses drugs for which patents have expired; as of 2019, it planned to divest itself of this business in 2020.
In July 2019, Pfizer announced plans t |
https://en.wikipedia.org/wiki/Santonin | Santonin is a drug which was widely used in the past as an anthelminthic. It is an organic compound consisting of colorless flat prisms, turning slightly yellow from the action of light and soluble in alcohol, chloroform and boiling water.
According to the US Pharmacopoeia, santonin occurs "in colorless, shining, flattened, prismatic crystals, odorless and nearly tasteless when first put in the mouth, but afterward developing a bitter taste; not altered by exposure to air, but turning yellow on exposure to light. Nearly insoluble in cold water; soluble in 40 parts of alcohol at 15 °C. (59 °F.), in 250 parts of boiling water, and in 8 parts of boiling alcohol; also soluble in 140 parts of ether, in 4 parts of chloroform, and in solutions of caustic alkalies. When heated to 170 °C. (338 °F.), santonin melts, and forms, if rapidly cooled, an amorphous mass, which instantly crystallizes oil coming in contact with a minute quantity of one of its solvents. At a higher temperature, it sublimes partly unchanged, and, when ignited, it is consumed, leaving no residue. Santonin is neutral to litmus paper moistened with alcohol. Santonin yields, with an alcoholic solution of potassium hydroxide, a bright pinkish-red liquid, which gradually becomes colorless. From its solution in caustic alkalies, santonin is completely precipitated by supersaturation with an acid".
Isolation
It is derived from santonica (the unexpanded flower-heads of Artemisia maritima var. stechmanniana). Others refer to A. cina or A. chamaemelifolia as being the derivative species.
The determination of the structure of santonin was the subject of intense early work. The initial photoproduct obtained from santonin is lumisantonin. In this rearrangement, the C-3 carbonyl group moves to C-2, the C-4 methyl moves to C-1, and the C-10 carbon inverts.
Anthelminthic use
Santonin paralyzes parasitic worms (helminths), allowing them to be passed out of the body. Santonin has the effect of paralyzing the anterior |
https://en.wikipedia.org/wiki/Candelilla%20wax | Candelilla wax is a wax derived from the leaves of the small Candelilla shrub native to northern Mexico and the southwestern United States, Euphorbia antisyphilitica, from the family Euphorbiaceae. It is yellowish-brown, hard, brittle, aromatic, and opaque to translucent.
Composition and production
With a melting point of 68.5–72.5 °C, candelilla wax consists of mainly hydrocarbons (about 50%, chains with 29–33 carbons), esters of higher molecular weight (20–29%), free acids (7–9%), and resins (12–14%, mainly triterpenoid esters). The high hydrocarbon content distinguishes this wax from carnauba wax. It is insoluble in water, but soluble in many organic solvents such as acetone, chloroform, benzene, and turpentine.
The wax is obtained by boiling the leaves and stems with dilute sulfuric acid, and the resulting "cerote" is skimmed from the surface and further processed. In this way, about 900 tons are produced annually.
Uses
It is mostly used mixed with other waxes to harden them without raising their melting point. As a food additive, candelilla wax has the E number E 902 and is used as a glazing agent. It also finds use in the cosmetic industry, as a component of lip balms and lotion bars. One of its major uses is as a binder for chewing gums.
Candelilla wax can be used as a substitute for carnauba wax and beeswax. It is also used for making varnish. |
https://en.wikipedia.org/wiki/IFolder | iFolder is an open-source application, developed by Novell, Inc., intended to allow cross-platform file sharing across computer networks.
iFolder operates on the concept of shared folders, where a folder is marked as shared and the contents of the folder are then synchronized to other computers over a network, either directly between computers in a peer-to-peer fashion or through a server. This is intended to allow a single user to synchronize files between different computers (for example between a work computer and a home computer) or share files with other users (for example a group of people who are collaborating on a project).
The core of the iFolder is actually a project called Simias. It is Simias which actually monitors files for changes, synchronizes these changes and controls the access permissions on folders. The actual iFolder clients (including a graphical desktop client and a web client) are developed as separate programs that communicate with the Simias back-end.
History
Originally conceived and developed at PGSoft before the company was taken over by Novell in 2000, iFolder was announced by Novell on March 19, 2001, and released on June 29, 2001 as a software package for Windows NT/2000 and Novell NetWare 5.1 or included with the forthcoming Novell NetWare 6.0. It also included the ability to access shared files through a web browser.
iFolder Professional Edition 2, announced on March 13, 2002 and released a month later, added support for Linux and Solaris and web access support for Windows CE and Palm OS. This edition was also designed to share files between millions of users in large companies, with increased reporting features for administrators. In 2003 iFolder won a Codie award.
On March 22, 2004, after their purchase of the Linux software companies Ximian and SUSE, Novell announced that they were releasing iFolder as an open source project under the GPL license. They also announced that the open source version of iFolder would use the M |
https://en.wikipedia.org/wiki/Olami%E2%80%93Feder%E2%80%93Christensen%20model | In physics, in the area of dynamical systems, the Olami–Feder–Christensen model is an earthquake model conjectured to be an example of self-organized criticality where local exchange dynamics are not conservative. Despite the original claims of the authors and subsequent claims of other authors such as Lise, whether or not the model is self organized critical remains an open question.
The system behaviour reproduces some empirical laws that earthquakes follow (such as the Gutenberg–Richter law and Omori's Law)
Model definition
The model is a simplification of the Burridge-Knopoff model, where the blocks move instantly to their balanced positions when submitted to a force greater than their friction.
Let S be a square lattice with L × L sites and let Kmn ≥ 0 be the tension at site (m,n). The sites with tension greater than 1 are called critical and go through a relaxation step where their tension spreads to their neighbours. Through analogy with the Burridge-Knopoff model, what is being simulated is a fault, where one of the lattice's dimensions is the flaw depth and the other one follows the flaw.
Model rules
If there are no critical sites, then the system suffers a continuous drive, until a site becomes critical:
else if the sites C1, C2, ..., Cm are critical the relaxation rule is applied in parallel:
where K'C is the tension prior to the relaxation and ΓC is the set of neighbours of site C. α is called the conservative parameter and can range from 0 to 0.25 in a square lattice. This can create a chain reaction which is interpreted as an earthquake.
These rules allow us to define a time variable that is update during the driving step
this is equivalent to define a constant drive
and assume the relaxation step is instantaneous, which is a good approximation for an earthquake model.
Behaviour and criticality
The system's behaviour is heavily influenced by the α parameter. For α=0.25 the system is conservative (in the sense that the |
https://en.wikipedia.org/wiki/Bak%E2%80%93Sneppen%20model | The Bak–Sneppen model is a simple model of co-evolution between interacting species. It was developed to show how self-organized criticality may explain key features of the fossil record, such as the distribution of sizes of extinction events and the phenomenon of punctuated equilibrium. It is named after Per Bak and Kim Sneppen.
The model dynamics repeatedly eliminates the least adapted species and mutates it and its neighbors to recreate the interaction between species. A comprehensive study of the details of this model can be found in Phys. Rev. E 53, 414–443 (1996). A solvable version of the model has been proposed in Phys. Rev. Lett. 76, 348–351 (1996), which shows that the dynamics evolves sub-diffusively, driven by a long-range memory.
An evolutionary local search heuristic based on the Bak–Sneppen model, called extremal optimization, has been introduced in The Bak–Sneppen model has been applied to the theory of scientific progress.
Description
We consider N species, which are associated with a fitness factor f(i). They are indexed by integers i around a ring. The algorithm consists in choosing the least fit species, and then replacing it and its two closest neighbors (previous and next integer) by new species, with a new random fitness. After a long run there will be a minimum required fitness, below which species don't survive. These "long-run" events are referred to as avalanches, and the model proceeds through these avalanches until it reaches a state of relative stability where all species' fitness are above a certain threshold.
See also
Evolutionary biology |
https://en.wikipedia.org/wiki/Radiolysis | Radiolysis is the dissociation of molecules by ionizing radiation. It is the cleavage of one or several chemical bonds resulting from exposure to high-energy flux. The radiation in this context is associated with ionizing radiation; radiolysis is therefore distinguished from, for example, photolysis of the Cl2 molecule into two Cl-radicals, where (ultraviolet or visible spectrum) light is used.
The chemistry of concentrated solutions under ionizing radiation is extremely complex. Radiolysis can locally modify redox conditions, and therefore the speciation and the solubility of the compounds.
Water decomposition
Of all the radiation-based chemical reactions that have been studied, the most important is the decomposition of water. When exposed to radiation, water undergoes a breakdown sequence into hydrogen peroxide, hydrogen radicals, and assorted oxygen compounds, such as ozone, which when converted back into oxygen releases great amounts of energy. Some of these are explosive. This decomposition is produced mainly by alpha particles, which can be entirely absorbed by very thin layers of water.
Summarizing, the radiolysis of water can be written as:
H2O \; ->[\text{Ionizing radiation}] \; e^{-}_{aq}, HO*, H*, HO2*, H3O^+, OH^-, H2O2, H2
Applications
Corrosion prediction and prevention in nuclear power plants
It is believed that the enhanced concentration of hydroxyl present in irradiated water in the inner coolant loops of a light-water reactor must be taken into account when designing nuclear power plants, to prevent coolant loss resulting from corrosion.
Hydrogen production
The current interest in nontraditional methods for the generation of hydrogen has prompted a revisit of radiolytic splitting of water, where the interaction of various types of ionizing radiation (α, β, and γ) with water produces molecular hydrogen. This reevaluation was further prompted by the current availability of large amounts of radiation sources contained in the fuel discharged f |
https://en.wikipedia.org/wiki/Trepidation | Trepidation (from Lat. trepidus, "trepidatious"), in now-obsolete medieval theories of astronomy, refers to hypothetical oscillation in the precession of the equinoxes. The theory was popular from the 9th to the 16th centuries.
The origin of the theory of trepidation comes from the Small Commentary to the Handy Tables written by Theon of Alexandria in the 4th century CE. In precession, the equinoxes appear to move slowly through the ecliptic, completing a revolution in approximately 25,800 years (according to modern astronomers). Theon states that certain (unnamed) ancient astrologers believed that the precession, rather than being a steady unending motion, instead reverses direction every 640 years. The equinoxes, in this theory, move through the ecliptic at the rate of 1 degree in 80 years over a span of 8 degrees, after which they suddenly reverse direction and travel back over the same 8 degrees. Theon describes but did not endorse this theory.
A more sophisticated version of this theory was adopted in the 9th century to explain a variation which Islamic astronomers incorrectly believed was affecting the rate of precession. This version of trepidation is described in De motu octavae sphaerae (On the Motion of the Eighth Sphere), a Latin translation of a lost Arabic original. The book is attributed to the Arab astronomer Thābit ibn Qurra, but this model has also been attributed to Ibn al-Adami and to Thabit's grandson, Ibrahim ibn Sinan. In this trepidation model, the oscillation is added to the equinoxes as they precess. The oscillation occurred over a period of 7000 years, added to the eighth (or ninth) sphere of the Ptolemaic system. "Thabit's" trepidation model was used in the Alfonsine Tables, which assigned a period of 49,000 years to precession. This version of trepidation dominated Latin astronomy in the later Middle Ages.
Islamic astronomers described other models of trepidation. In the West, an alternative to De motu octavae sphaerae was part of t |
https://en.wikipedia.org/wiki/Picloram | Picloram is a systemic herbicide used for general woody plant control. It also controls a wide range of broad-leaved weeds, but most grasses are resistant. A chlorinated derivative of picolinic acid, picloram is in the pyridine family of herbicides.
Picloram can be sprayed on foliage, injected into plants, applied to cut surfaces, or placed at the base of the plant where it will leach to the roots. Once absorbed by the foliage, stem, or roots, picloram is transported throughout the plant.
Herbicides containing picloram are sold under a variety of brand names. Dow Chemicals and now Dow AgroSciences sell herbicides containing it under the brand name Tordon.
During the Vietnam War, picloram and other herbicides were combined to make Agent White (commercially available as Tordon 101) and enhanced Agent Orange, which was previously conducted by the British military during the Malayan Emergency. Large quantities of these herbicides were sprayed by U.S. forces in areas where they considered its long-term persistence desirable, such as inland forests.
Safety
Picloram is of moderate toxicity to the eyes and only mildly toxic on the skin. No history of human intoxication by picloram has been documented, so symptoms of acute exposure are difficult to characterize.
Picloram is the most persistent of its family of herbicides. It does not adhere to soil, so may leach to groundwater, and has in fact been detected there. It is degraded in soil and water mainly by microbes. Picloram has very little tendency to accumulate in aquatic life.
Gardeners who use dung as fertilizer should check to make certain that the animal source has not grazed on picloram-treated hay, as the dung still has broadleaf-killing potency.
In regards to occupational exposures, the U. S. Occupational Safety and Health Administration has established a permissible exposure limit of 15 mg/m3 total exposure and 5 mg/m3 for respiratory exposure, over an eight-hour workshift. |
https://en.wikipedia.org/wiki/Sanmina%20Corporation | Sanmina Corporation is an American electronics manufacturing services (EMS) provider headquartered in San Jose, California that serves original equipment manufacturers in communications and computer hardware fields. The firm has nearly 80 manufacturing sites, and is one of the world’s largest independent manufacturers of printed circuit boards and backplanes. , it is ranked number 482 in the Fortune 500 list.
History
Sanmina was founded by Jure Sola and Milan Mandarić in 1980 as a printed circuit board manufacturer. It was named after Milan Manadarić's daughters Sandra and Jasmina. During the 1980s, it expanded into manufacturing backplanes and subassemblies for the telecommunications industry. During the 1990s, the company grew, producing complete products for major OEM companies and completing a number of acquisitions. Jure Sola became CEO and Chairman of Sanmina in 1991. The company completed an initial public offering on NASDAQ in 1993.
Merger and name changes
In December 2001, Sanmina merged with SCI Systems of Huntsville, Alabama, for $6 billion in cash, stock, and debt. Although Sanmina was only half as large as SCI at the time, it was in a better cash position because its core telecommunications business was performing well, whereas SCI's lower-margin businesses such as personal computer manufacturing, were struggling. Shortly after, Sanmina-SCI bought E-M Solutions, a bankrupt Fremont, California electronics manufacturer, for $110 million in cash. Then in early 2002, Sanmina acquired Rancho Santa Margarita-based Viking Interworks for $15 million ($10.9 million in cash and 390,000 shares of Sanmina stock worth $10.26 per share at the time).
On November 15, 2012, the company changed its name to Sanmina.
On July 2, 2015, the company announced that it had acquired the CertainSource Technology Group.
Change of Leadership
Bob Eulau replaced co-founder Jure Sola becoming the CEO effective October 2, 2017. After this change, Sola assumed the role of Execut |
https://en.wikipedia.org/wiki/Computational%20finance | Computational finance is a branch of applied computer science that deals with problems of practical interest in finance. Some slightly different definitions are the study of data and algorithms currently used in finance and the mathematics of computer programs that realize financial models or systems.
Computational finance emphasizes practical numerical methods rather than mathematical proofs and focuses on techniques that apply directly to economic analyses. It is an interdisciplinary field between mathematical finance and numerical methods. Two major areas are efficient and accurate computation of fair values of financial securities and the modeling of stochastic time series.
History
The birth of computational finance as a discipline can be traced to Harry Markowitz in the early 1950s. Markowitz conceived of the portfolio selection problem as an exercise in mean-variance optimization. This required more computer power than was available at the time, so he worked on useful algorithms for approximate solutions. Mathematical finance began with the same insight, but diverged by making simplifying assumptions to express relations in simple closed forms that did not require sophisticated computer science to evaluate.
In the 1960s, hedge fund managers such as Ed Thorp and Michael Goodkin (working with Harry Markowitz, Paul Samuelson and Robert C. Merton) pioneered the use of computers in arbitrage trading. In academics, sophisticated computer processing was needed by researchers such as Eugene Fama in order to analyze large amounts of financial data in support of the efficient-market hypothesis.
During the 1970s, the main focus of computational finance shifted to options pricing and analyzing mortgage securitizations. In the late 1970s and early 1980s, a group of young quantitative practitioners who became known as "rocket scientists" arrived on Wall Street and brought along personal computers. This led to an explosion of both the amount and variety of computational |
https://en.wikipedia.org/wiki/MDSP | MDSP is a multiprocessor DSP family from Cradle Technologies. Currently used mostly in streaming video processing in broadcast (internet and terrestrial) and video surveillance security markets.
It is a loosely coupled architecture that employs compute and Input/output (IO) subsystems with programmable (software defined) IO, consisting of general purpose and signal processing cores. The general purpose cores are used for control and IO processing and the DSP cores for fixed or floating point computation.
MDSP is similar in architecture to the Cell (microprocessor) processor from STI (Sony, Toshiba and IBM)
except it has multiple processing elements. Cell is PowerPC based. The PE (processing element) or GPP (General purpose processor) units are 32 bit general purpose RISC-like cores coupled with signal processing units (DSP or DSE) via a databus.
Development tools
The initial software development kit (sdk4) was based on cygwin 1.3.x and Cradles umgcc (GCC port). Sdk5 is based on Cygwin 1.5.x and cragcc (gcc port).
The chips are programmed in a mix of C and CLASM (C like assembly). The PEs can be programmed in C, the DSEs and MTEs are programmed in CLASM. The programmer has to manage resource allocation using semaphores, paying special attention to keeping all DSP units fed with instructions.
External links
CT3400 datasheet
CT3600 product brief
CT3600 datasheet
software development kit download
Digital signal processors |
https://en.wikipedia.org/wiki/Central%20tolerance | In immunology, central tolerance (also known as negative selection) is the process of eliminating any developing T or B lymphocytes that are autoreactive, i.e. reactive to the body itself. Through elimination of autoreactive lymphocytes, tolerance ensures that the immune system does not attack self peptides. Lymphocyte maturation (and central tolerance) occurs in primary lymphoid organs such as the bone marrow and the thymus. In mammals, B cells mature in the bone marrow and T cells mature in the thymus.
Central tolerance is not perfect, so peripheral tolerance exists as a secondary mechanism to ensure that T and B cells are not self-reactive once they leave primary lymphoid organs. Peripheral tolerance is distinct from central tolerance in that it occurs once developing immune cells exit primary lymphoid organs (the thymus and bone-marrow), prior to their export into the periphery.
Function of central tolerance
Central tolerance is essential to proper immune cell functioning because it helps ensure that mature B cells and T cells do not recognize self-antigens as foreign microbes. More specifically, central tolerance is necessary because T cell receptors (TCRs) and B cell receptors (BCRs) are made by cells through random somatic rearrangement. This process, known as V(D)J recombination, is important because it increases the receptor diversity which increases the likelihood that B cells and T cells will have receptors for novel antigens. Junctional diversity occurs during recombination and serves to further increase the diversity of BCRs and TCRs. The production of random TCRs and BCRs is an important method of defense against microbes due to their high mutation rate. This process also plays an important role in promoting the survival of a species, because there will be a variety of receptor arrangements within a species – this enables a very high chance of at least one member of the species having receptors for a novel antigen.
While the process of somatic recom |
https://en.wikipedia.org/wiki/Elater | An elater is a cell (or structure attached to a cell) that is hygroscopic, and therefore will change shape in response to changes in moisture in the environment. Elaters come in a variety of forms, but are always associated with plant spores. In many plants that do not have seeds, they function in dispersing the spores to a new location. Mosses do not have elaters, but peristomes which change shape with changes in humidity or moisture to allow for a gradual release of spores.
Horsetail elaters
In the horsetails, elaters are four ribbon-like appendages attached to the spores. These appendages develop from an outer spiral layer of the spore wall. At maturity, the four strips peel away from the inner wall, except at a single point on the spore where all four strips are attached.
Under moist conditions, the elaters curl tightly around the spore. The wet spores tend to stick to each other and to nearby surfaces because of surface tension. When conditions are dry, the spores no longer stick to each other and are more easily dispersed. At that time, the elaters uncoil to extend out from the spore and will catch air currents. The fact that they are extended only when conditions are dry means that successful spore dispersal is more likely.
Liverwort elaters
In the liverworts also known as hepaticopsida [example Riccia,Marchantia], elaters are cells that develop in the sporophyte alongside the spores. They are complete cells, usually with helical thickenings at maturity that respond to moisture content.
In most liverworts, the elaters are unattached, but in some leafy species (such as Frullania) a few elaters will remain attached to the inside of the sporangium (spore capsule).
Hornwort pseudo-elaters
In the hornworts, elaters are branched clusters of cells that develop in the sporophyte alongside the spores. They are complete cells, usually without helical thickenings (except in the Dendrocerotaceae). |
https://en.wikipedia.org/wiki/Cornus%20mas | Cornus mas, commonly known as cornel (also the Cornelian cherry, European cornel or Cornelian cherry dogwood), is a species of shrub or small tree in the dogwood family Cornaceae native to Western Europe, Southern Europe, and Southwestern Asia.
Description
It is a medium to large deciduous shrub or small tree growing to 5–12 m tall, with dark brown branches and greenish twigs. The leaves are opposite, 4–10 cm long and 2–4 cm broad, with an ovate to oblong shape and an entire margin. The flowers are small (5–10 mm in diameter), with four yellow petals, produced in clusters of 10–25 together in the late winter (between February and March in the UK), well before the leaves appear. The fruit is an oblong red drupe 2 cm long and 1.5 cm in diameter, containing a single seed.
Uses
Fruit
The fruits are red berries. When ripe on the plant, they bear a resemblance to coffee berries, and ripen in mid- to late summer. The fruit is edible and widely popular in Iran, where it is believed to have various medicinal properties and provide health benefits. It is also used in Eastern Europe, the UK, and British Columbia, Canada, but the unripe fruit is astringent. When ripe, the fruit is dark ruby red or a bright yellow. It has an acidic flavor which is best described as a mixture of cranberry and sour cherry. It is mainly used for making jam. It is widely used in Azerbaijan to make pickles, added to rice or make beverages. In Armenia, Cornus berries are used to make vodka. In Romania and Moldova, the berries are used to make an alcoholic beverage known as cornată. In Bulgaria the berries are widely used to make Kompot.
The fruit of Cornus mas (together with the fruit of C. officinalis) has a history of use in traditional Chinese medicine in which it is known as , and used to retain the jing.
Flowers
The species is also grown as an ornamental plant for its late winter yellow flowers, which open earlier than those of Forsythia. While Cornus mas flowers are not as large and vi |
https://en.wikipedia.org/wiki/Mathematics%20of%20Sudoku | Mathematics can be used to study Sudoku puzzles to answer questions such as "How many filled Sudoku grids are there?", "What is the minimal number of clues in a valid puzzle?" and "In what ways can Sudoku grids be symmetric?" through the use of combinatorics and group theory.
The analysis of Sudoku is generally divided between analyzing the properties of unsolved puzzles (such as the minimum possible number of given clues) and analyzing the properties of solved puzzles. Initial analysis was largely focused on enumerating solutions, with results first appearing in 2004.
For classical Sudoku, the number of filled grids is 6,670,903,752,021,072,936,960 (), which reduces to 5,472,730,538 essentially different solutions under the validity preserving transformations. There are 26 possible types of symmetry, but they can only be found in about 0.005% of all filled grids. An ordinary puzzle with a unique solution must have at least 17 clues. There is a solvable puzzle with at most 21 clues for every solved grid. The largest minimal puzzle found so far has 40 clues in the 81 cells.
Similar results are known for variants and smaller grids. No exact results are known for Sudokus larger than the classical 9×9 grid, although there are estimates which are believed to be fairly accurate.
Puzzles
Minimum number of givens
Ordinary Sudokus (proper puzzles) have a unique solution. A minimal Sudoku is a Sudoku from which no clue can be removed leaving it a proper Sudoku. Different minimal Sudokus can have a different number of clues. This section discusses the minimum number of givens for proper puzzles.
Ordinary Sudoku
Many Sudokus have been found with 17 clues, although finding them is not a trivial task. A paper by Gary McGuire, Bastian Tugemann, and Gilles Civario, released on 1 January 2012, explains how it was proved through an exhaustive computer search based on hitting set enumeration that the minimum number of clues in any proper Sudoku is 17.
Symmetrical Sudoku
The fe |
https://en.wikipedia.org/wiki/Ergodic%20sequence | In mathematics, an ergodic sequence is a certain type of integer sequence, having certain equidistribution properties.
Definition
Let be an infinite, strictly increasing sequence of positive integers. Then, given an integer q, this sequence is said to be ergodic mod q if, for all integers , one has
where
and card is the count (the number of elements) of a set, so that is the number of elements in the sequence A that are less than or equal to t, and
so is the number of elements in the sequence A, less than t, that are equivalent to k modulo q. That is, a sequence is an ergodic sequence if it becomes uniformly distributed mod q as the sequence is taken to infinity.
An equivalent definition is that the sum
vanish for every integer k with .
If a sequence is ergodic for all q, then it is sometimes said to be ergodic for periodic systems.
Examples
The sequence of positive integers is ergodic for all q.
Almost all Bernoulli sequences, that is, sequences associated with a Bernoulli process, are ergodic for all q. That is, let be a probability space of random variables over two letters . Then, given , the random variable is 1 with some probability p and is zero with some probability 1-p; this is the definition of a Bernoulli process. Associated with each is the sequence of integers
Then almost every sequence is ergodic.
See also
Ergodic theory
Ergodic process, for the use of the term in signal processing
Ergodic theory
Integer sequences |
https://en.wikipedia.org/wiki/Global%20Atmosphere%20Watch | The Global Atmosphere Watch (GAW) is a worldwide system established by the World Meteorological Organizationa United Nations agencyto monitor trends in the Earth's atmosphere. It arose out of concerns for the state of the atmosphere in the 1960s.
Mission
The Global Atmosphere Watch's mission is quite straightforward, consisting of three concise points:
To make reliable, comprehensive observations of the chemical composition and selected physical characteristics of the atmosphere on global and regional scales;
To provide the scientific community with the means to predict future atmospheric states;
To organize assessments in support of formulating environmental policy.
Goals
The GAW program is guided by 8 strategic goals:
To improve the measurements programme for better geographical and temporal coverage and for near real-time monitoring capability;
To complete the quality assurance/quality control system;
To improve availability of data and promote their use;
To improve communication and cooperation between all GAW components and with the scientific community;
To identify and clarify changing roles of GAW components;
To maintain present and solicit new support and collaborations for the GAW programme;
To intensify capacity-building in developing countries;
To enhance the capabilities of National Meteorological and Hydrological Services in providing urban environmental air quality services.
Moreover, the programme seeks not only to understand changes in the Earth's atmosphere, but also to forecast them, and perhaps control the human activities that cause them.
Genesis
The original reason for testing the atmosphere for trace chemicals was mere scientific interest, but of course, many scientists eventually wondered what effects these trace chemicals could have on the atmosphere, and on life.
The GAW's genesis began as far back as the 1950s when the World Meteorological Organization began a programme of monitoring the atmosphere for trace chemicals, and also r |
https://en.wikipedia.org/wiki/Community-acquired%20pneumonia | Community-acquired pneumonia (CAP) refers to pneumonia (any of several lung diseases) contracted by a person outside of the healthcare system. In contrast, hospital-acquired pneumonia (HAP) is seen in patients who have recently visited a hospital or who live in long-term care facilities. CAP is common, affecting people of all ages, and its symptoms occur as a result of oxygen-absorbing areas of the lung (alveoli) filling with fluid. This inhibits lung function, causing dyspnea, fever, chest pains and cough.
CAP, the most common type of pneumonia, is a leading cause of illness and death worldwide. Its causes include bacteria, viruses, fungi and parasites. CAP is diagnosed by assessing symptoms, performing a physical examination, by x-ray or by sputum examination. Patients with CAP sometimes require hospitalization, and it is treated primarily with antibiotics, antipyretics and cough medicine. Some forms of CAP can be prevented by vaccination and by abstaining from tobacco products.
Signs and symptoms
Common symptoms
Coughing which produces greenish or yellow sputum
A high fever, accompanied by sweating, chills and shivering
Sharp, stabbing chest pains
Rapid, shallow, often painful breathing
Less-common symptoms
Coughing up blood (hemoptysis)
Headaches, including migraines
Loss of appetite
Excessive fatigue
Bluish skin (cyanosis)
Nausea
Vomiting
Diarrhea
Joint pain (arthralgia)
Muscle aches (myalgia)
Rapid heartbeat
Dizziness or lightheadedness
In the elderly
New or worsening confusion
Hypothermia
Poor coordination, which may lead to falls
In infants
Unusual sleepiness
Yellowing of the skin (jaundice)
Difficulty feeding
Complications
Major complications of CAP include:
Sepsis - A life-threatening reaction to infection. A common cause of sepsis is bacterial pneumonia, frequently the result of infection with streptococcus pneumoniae. Patients with sepsis require intensive care with blood pressure monitoring and support against hypotension |
https://en.wikipedia.org/wiki/Passiflora%20tarminiana | Passiflora tarminiana (or banana passionfruit) is a species of passionfruit. The yellow fruits are edible and their resemblance to small, straight bananas has given it the name banana passionfruit in some countries. It is native to the uplands of tropical South America and is now cultivated in many countries. In Hawaii and New Zealand it is now considered an invasive species. It was given the name banana passionfruit in New Zealand, where passionfruit are also prevalent. In Hawaii, it is called banana poka. In its Latin American homeland, it is known as curuba, curuba de Castilla, or curuba sabanera blanca (Colombia); taxo, tacso, tagso, tauso (Ecuador); parcha, taxo (Venezuela), tumbo or curuba (Bolivia); tacso, tumbo, tumbo del norte, trompos, tintin or purpur (Peru).
Passiflora tarminiana belongs to the Tacsonia subgenus of Passiflora. It has been known under a number of different names and was only formally described in 2001.
Description
Passiflora tarminiana is a high climbing vine with hairy stems and petioles. Where the petioles join the stem it has stipules which are 4–7 by 2–3 mm and are soon deciduous. The leaves are three-lobed and hairy below but usually hairless above. The flowers are solitary and hang downwards. The base of the flower has pale green bracts enclosing a swollen nectary chamber. The floral tube (hypanthium) is 6–8 × 0.7–1 cm and pale green, while the sepals and petals are 3–6 cm long, pink and perpendicular to the floral tube, or reflexed. Fruits taper at both ends, are 10–14 cm long by 3.5–4.5 cm wide and ripen to yellow or light orange. The fruit contain many seeds which are embedded in an edible, orange aril.
Mollissima and its close relative Passiflora mixta are vines with cylindrical stems densely coated with yellow hairs, and are vigorous climbers, growing up to seven metres. The leaves are a shiny green with clearly defined veins, the flower is large, pink and green petalled with a yellow and white centre. The fruit is yellow-o |
https://en.wikipedia.org/wiki/Tragus%20%28ear%29 | The tragus is a small pointed eminence of the external ear, situated in front of the concha, and projecting backward over the meatus. It also is the name of hair growing at the entrance of the ear. Its name comes the Ancient Greek (), meaning 'goat', and is descriptive of its general covering on its under surface with a tuft of hair, resembling a goat's beard. The nearby antitragus projects forwards and upwards.
Because the tragus faces rearwards, it aids in collecting sounds from behind. These sounds are delayed more than sounds arriving from the front, assisting the brain to sense front vs. rear sound sources.
In a positive fistula test (for the presence of a fistula from cholesteatoma to the labyrinth), pressure on the tragus causes vertigo or eye deviation by inducing movement of perilymph.
Other animals
The tragus is a key feature in many bat species. As a piece of skin in front of the ear canal, it plays an important role in directing sounds into the ear for prey location and navigation via echolocation. Because the tragus tends to be prominent in bats, it is an important feature in identifying bat species.
The tragus allows echolocating bat species to vertically discriminate the objects around them, which is key to identifying where prey items and obstacles are in three-dimensional space.
In studies where an individual's tragi are temporarily glued out of their normal positions, the bat's navigational acuity is one-fourth as effective as individuals with unmodified tragi.
Based on this study, the authors concluded that the tragus's function is to create acoustic cues to determine the direction of a target in the vertical plane.
Not all echolocating bats possess tragi, however.
Horseshoe bats are one such family; the way in which the outer bottom edge of the ear folds in on itself is thought to function in a similar way to the tragus in other families.
Additional images
See also
Auricular branch of the vagus nerve
Tragal pressure
Tragus piercing |
https://en.wikipedia.org/wiki/Cipher%20runes | Cipher runes, or cryptic runes, are the cryptographical replacement of the letters of the runic alphabet.
Preservation
The knowledge of cipher runes was best preserved in Iceland, and during the 17th–18th centuries, Icelandic scholars produced several treatises on the subject. The most notable of these is the manuscript Runologia by Jón Ólafsson (1705–1779), which he wrote in Copenhagen (1732–1752). It thoroughly treats numerous cipher runes and runic ciphers, and it is now preserved in the Arnamagnæan Institute in Copenhagen.
Jón Ólafsson's treatise presents the Younger Futhark in the Viking Age order, which means that the m-rune precedes the l-rune. This small detail was of paramount importance for the interpretation of Viking Age cipher runes because in the 13th century the two runes had changed places through the influence of the Latin alphabet where l precedes m. Since the medieval runic calendar used the post-13th-century order, the early runologists of the 17th–18th centuries believed that the l-m order was the original one, and the order of the runes is of vital importance for the interpretation of cipher runes.
Structure of the ciphers
In the runic alphabet, the runes have their special order and are divided into groups. In the Younger Futhark, which has 16 letters, they are divided into three groups. The Icelandic tradition calls the first group (f, u, þ, ã, r and k) "Freyr's ætt", the second group (h, n, i, a and s) "Hagal's ætt" and the third group (t, b, m, l and ʀ) "Tyr's ætt". In order to make the inscription even harder to decipher, Freyr's ætt and Tyr's ætt change places so that group one is group three and vice versa. However, in several cases the ætts are counted in their correct order, and not backwards. There are numerous forms of cipher runes, but they are all based on the principle of giving the number of the ætt and the number of the rune within the ætt.
The tent runes are based on strokes added to the four arms of an X shape: Each X re |
https://en.wikipedia.org/wiki/Gibbing | Gibbing is the process of preparing salt herring (or soused herring), in which the gills and part of the gullet are removed from the fish, eliminating any bitter taste. The liver and pancreas are left in the fish during the salt-curing process because they release enzymes essential for flavor. The fish is then cured in a barrel with one part salt to 20 herring. Today many variations and local preferences exist in this process.
History
According to a popular story, the process of gibbing was invented by Willem Beukelszoon ( Willem Beuckelsz, William Buckels or William Buckelsson), a 14th-century fisherman from Biervliet, Zealand. The invention of this fish preservation technique led to the Dutch becoming a seafaring power.
Sometime between 1380 and 1386, Beuckelsz discovered that "salt fish will keep, and that fish that can be kept can be packed and can be exported".
Beuckelsz' invention of gibbing created an export industry for salt herring that was monopolized by the Dutch. They began to build ships and eventually moved from trading in herring to colonizing and the Dutch Empire.
The Emperor Charles V erected a statue to Beuckelsz honouring him as the benefactor of his country, and Queen Mary of Hungary after finding his tomb sat upon it and ate a herring.
Herring is still very important to the Dutch who celebrate (Flag Day) each spring, as a tradition that dates back to the 14th century when fishermen went out to sea in their small boats to capture the annual catch, and to preserve and export their catch abroad.
See also
Herring Buss |
https://en.wikipedia.org/wiki/Majorana%20equation | In physics, the Majorana equation is a relativistic wave equation. It is named after the Italian physicist Ettore Majorana, who proposed it in 1937 as a means of describing fermions that are their own antiparticle. Particles corresponding to this equation are termed Majorana particles, although that term now has a more expansive meaning, referring to any (possibly non-relativistic) fermionic particle that is its own anti-particle (and is therefore electrically neutral).
There have been proposals that massive neutrinos are described by Majorana particles; there are various extensions to the Standard Model that enable this. The article on Majorana particles presents status for the experimental searches, including details about neutrinos. This article focuses primarily on the mathematical development of the theory, with attention to its discrete and continuous symmetries. The discrete symmetries are charge conjugation, parity transformation and time reversal; the continuous symmetry is Lorentz invariance.
Charge conjugation plays an outsize role, as it is the key symmetry that allows the Majorana particles to be described as electrically neutral. A particularly remarkable aspect is that electrical neutrality allows several global phases to be freely chosen, one each for the left and right chiral fields. This implies that, without explicit constraints on these phases, the Majorana fields are naturally CP violating. Another aspect of electric neutrality is that the left and right chiral fields can be given distinct masses. That is, electric charge is a Lorentz invariant, and also a constant of motion; whereas chirality is a Lorentz invariant, but is not a constant of motion for massive fields. Electrically neutral fields are thus less constrained than charged fields. Under charge conjugation, the two free global phases appear in the mass terms (as they are Lorentz invariant), and so the Majorana mass is described by a complex matrix, rather than a single number. In sho |
https://en.wikipedia.org/wiki/Developmental%20Biology%20%28journal%29 | Developmental Biology is a peer-reviewed scientific journal. It was established in 1959 and is the official journal of the Society for Developmental Biology. It publishes research on the mechanisms of development, differentiation, and growth in animals and plants at the molecular, cellular, and genetic levels. The journal is published twice a month by Elsevier.
Abstracting and indexing
The journal is abstracted an indexed in:
According to the Journal Citation Reports, the journal has a 2020 impact factor of 3.582. Looking at Scimago Journal & Country Rank data trends, citations per document declined substantially between 1999 and 2020, while the number of uncited documents increased over the same period. The number of citable documents per year published has decreased from a high of around 1,650 in 2008 to 661 in 2021. |
https://en.wikipedia.org/wiki/Web%20API | A web API is an application programming interface (API) for either a web server or a web browser.
As a web development concept, it can be related to a web application's client side (including any web frameworks being used).
A server-side web API consists of one or more publicly exposed endpoints to a defined request–response message system, typically expressed in JSON or XML by means of an HTTP-based web server.
A server API (SAPI) is not considered a server-side web API, unless it is publicly accessible by a remote web application.
Client side
A client-side web API is a programmatic interface to extend functionality within a web browser or other HTTP client. Originally these were most commonly in the form of native plug-in browser extensions however most newer ones target standardized JavaScript bindings.
The Mozilla Foundation created their WebAPI specification which is designed to help replace native mobile applications with HTML5 applications.
Google created their Native Client architecture which is designed to help replace insecure native plug-ins with secure native sandboxed extensions and applications. They have also made this portable by employing a modified LLVM AOT compiler.
Server side
A server-side web API consists of one or more publicly exposed endpoints to a defined request–response message system, typically expressed in JSON or XML. The web API is exposed most commonly by means of an HTTP-based web server.
Mashups are web applications which combine the use of multiple server-side web APIs. Webhooks are server-side web APIs that take input as a Uniform Resource Identifier (URI) that is designed to be used like a remote named pipe or a type of callback such that the server acts as a client to dereference the provided URI and trigger an event on another server which handles this event thus providing a type of peer-to-peer IPC.
Endpoints
Endpoints are important aspects of interacting with server-side web APIs, as they specify where resources li |
https://en.wikipedia.org/wiki/Spin%20connection | In differential geometry and mathematical physics, a spin connection is a connection on a spinor bundle. It is induced, in a canonical manner, from the affine connection. It can also be regarded as the gauge field generated by local Lorentz transformations. In some canonical formulations of general relativity, a spin connection is defined on spatial slices and can also be regarded as the gauge field generated by local rotations.
The spin connection occurs in two common forms: the Levi-Civita spin connection, when it is derived from the Levi-Civita connection, and the affine spin connection, when it is obtained from the affine connection. The difference between the two of these is that the Levi-Civita connection is by definition the unique torsion-free connection, whereas the affine connection (and so the affine spin connection) may contain torsion.
Definition
Let be the local Lorentz frame fields or vierbein (also known as a tetrad), which is a set of orthonormal space time vector fields that diagonalize the metric tensor
where is the spacetime metric and is the Minkowski metric. Here, Latin letters denote the local Lorentz frame indices; Greek indices denote general coordinate indices. This simply expresses that , when written in terms of the basis , is locally flat. The Greek vierbein indices can be raised or lowered by the metric, i.e. or . The Latin or "Lorentzian" vierbein indices can be raised or lowered by or respectively. For example, and
The torsion-free spin connection is given by
where are the Christoffel symbols. This definition should be taken as defining the torsion-free spin connection, since, by convention, the Christoffel symbols are derived from the Levi-Civita connection, which is the unique metric compatible, torsion-free connection on a Riemannian Manifold. In general, there is no restriction: the spin connection may also contain torsion.
Note that using the gravitational covariant derivative of the contravariant vector . Th |
https://en.wikipedia.org/wiki/List%20of%20Wenninger%20polyhedron%20models | This is an indexed list of the uniform and stellated polyhedra from the book Polyhedron Models, by Magnus Wenninger.
The book was written as a guide book to building polyhedra as physical models. It includes templates of face elements for construction and helpful hints in building, and also brief descriptions on the theory behind these shapes. It contains the 75 nonprismatic uniform polyhedra, as well as 44 stellated forms of the convex regular and quasiregular polyhedra.
Models listed here can be cited as "Wenninger Model Number N", or WN for brevity.
The polyhedra are grouped in 5 tables: Regular (1–5), Semiregular (6–18), regular star polyhedra (20–22,41), Stellations and compounds (19–66), and uniform star polyhedra (67–119). The four regular star polyhedra are listed twice because they belong to both the uniform polyhedra and stellation groupings.
Platonic solids (regular convex polyhedra) W1 to W5
Archimedean solids (Semiregular) W6 to W18
Kepler–Poinsot polyhedra (Regular star polyhedra) W20, W21, W22 and W41
Stellations: models W19 to W66
Stellations of octahedron
Stellations of dodecahedron
Stellations of icosahedron
Stellations of cuboctahedron
Stellations of icosidodecahedron
Uniform nonconvex solids W67 to W119
See also
List of uniform polyhedra
The fifty nine icosahedra
List of polyhedral stellations |
https://en.wikipedia.org/wiki/Rhizosphere | The rhizosphere is the narrow region of soil or substrate that is directly influenced by root secretions and associated soil microorganisms known as the root microbiome. Soil pores in the rhizosphere can contain many bacteria and other microorganisms that feed on sloughed-off plant cells, termed rhizodeposition, and the proteins and sugars released by roots, termed root exudates. This symbiosis leads to more complex interactions, influencing plant growth and competition for resources. Much of the nutrient cycling and disease suppression by antibiotics required by plants, occurs immediately adjacent to roots due to root exudates and metabolic products of symbiotic and pathogenic communities of microorganisms. The rhizosphere also provides space to produce allelochemicals to control neighbours and relatives.
The rhizoplane refers to the root surface including its associated soil particles which closely interact with each other. The plant-soil feedback loop and other physical factors occurring at the plant-root soil interface are important selective pressures in communities and growth in the rhizosphere and rhizoplane.
Background
The term "rhizosphere" was used first in 1904 by the German plant physiologist Lorenz Hiltner to describe how plant roots interface with surrounding soil. The prefix rhiza- comes from the Greek, and means "root". Hiltner postulated the rhizosphere was a region surrounding the plant roots, and populated with microorganisms under some degree of control by chemicals released from the plant roots.
Chemical interactions
Chemical availability
Plant roots may exude 20-40% of the sugars and organic acids - photosynthetically fixed carbon. Plant root exudates, such as organic acids, change the chemical structure and the biological communities of the rhizosphere in comparison with the bulk soil or parent soil. Concentrations of organic acids and saccharides affect the ability of the biological communities to shuttle phosphorus, nitrogen, potassium |
https://en.wikipedia.org/wiki/Pure%20fusion%20weapon | A pure fusion weapon is a hypothetical hydrogen bomb design that does not need a fission "primary" explosive to ignite the fusion of deuterium and tritium, two heavy isotopes of hydrogen used in fission-fusion thermonuclear weapons. Such a weapon would require no fissile material and would therefore be much easier to develop in secret than existing weapons. Separating weapons-grade uranium (U-235) or breeding plutonium (Pu-239) requires a substantial and difficult-to-conceal industrial investment, and blocking the sale and transfer of the needed machinery has been the primary mechanism to control nuclear proliferation to date.
Explanation
All current thermonuclear weapons use a fission bomb as a first stage to create the high temperatures and pressures necessary to start a fusion reaction between deuterium and tritium in a second stage. For many years, nuclear weapon designers have researched whether it is possible to create high enough temperatures and pressures inside a confined space to ignite a fusion reaction, without using fission. Pure fusion weapons offer the possibility of generating arbitrarily small nuclear yields because no critical mass of fissile fuel need be assembled for detonation, as with a conventional fission primary needed to spark a fusion explosion. There is also the advantage of reduced collateral damage stemming from fallout because these weapons would not create the highly radioactive byproducts made by fission-type weapons. These weapons would be lethal not only because of their explosive force, which could be large compared to bombs based on chemical explosives, but also because of the neutrons they generate.
While various neutron source devices have been developed, some of them based on fusion reactions, none of them are able to produce a net energy yield, either in controlled form for energy production or uncontrolled for a weapon.
Progress
Despite the many millions of dollars spent by the U.S. between 1952 and 1992 to produce a pur |
https://en.wikipedia.org/wiki/Orbifold%20notation | In geometry, orbifold notation (or orbifold signature) is a system, invented by the mathematician William Thurston and promoted by John Conway, for representing types of symmetry groups in two-dimensional spaces of constant curvature. The advantage of the notation is that it describes these groups in a way which indicates many of the groups' properties: in particular, it follows William Thurston in describing the orbifold obtained by taking the quotient of Euclidean space by the group under consideration.
Groups representable in this notation include the point groups on the sphere (), the frieze groups and wallpaper groups of the Euclidean plane (), and their analogues on the hyperbolic plane ().
Definition of the notation
The following types of Euclidean transformation can occur in a group described by orbifold notation:
reflection through a line (or plane)
translation by a vector
rotation of finite order around a point
infinite rotation around a line in 3-space
glide-reflection, i.e. reflection followed by translation.
All translations which occur are assumed to form a discrete subgroup of the group symmetries being described.
Each group is denoted in orbifold notation by a finite string made up from the following symbols:
positive integers
the infinity symbol,
the asterisk, *
the symbol o (a solid circle in older documents), which is called a wonder and also a handle because it topologically represents a torus (1-handle) closed surface. Patterns repeat by two translation.
the symbol (an open circle in older documents), which is called a miracle and represents a topological crosscap where a pattern repeats as a mirror image without crossing a mirror line.
A string written in boldface represents a group of symmetries of Euclidean 3-space. A string not written in boldface represents a group of symmetries of the Euclidean plane, which is assumed to contain two independent translations.
Each symbol corresponds to a distinct transformation:
an |
https://en.wikipedia.org/wiki/Hub%20dynamo | A hub dynamo is a small electrical generator built into the hub of a bicycle wheel that is usually used to power lights. Often the hub "dynamo" is not actually a dynamo, which creates DC, but a low-power magneto that creates AC. Most modern hub dynamos are regulated to 3 watts at 6 volts, although some will drive up to 6 watts at 12 volts.
Models
The market was largely pioneered by Sturmey-Archer with their Dynohub of the 1930s–1970s. This competed effectively with contemporaneous bottle dynamos and bottom-bracket generators, but the Dynohub was heavy with its steel housing and was discontinued in the 1980s. Around 2009, Sturmey-Archer released new hub dynamo/drum brake units with an aluminum housing, designated X-FDD and XL-FDD.
The Schmidt Original Nabendynamo (SON) can power two 6-volt lamps in series at speeds above about , and Schmidt manufactures lamps designed to facilitate this. These lamps have optics based on the Bisy FL road lights. The efficiency of the SON is quoted by the manufacturers at 65% (so just over 5 W of the rider's output is diverted to produce 3 W of electrical power) but this applies at only . At higher speeds the efficiency falls. Bicycle dynamos instead use permanent magnets to eliminate the need for a battery to excite the field and initiate electrical generation.
Shimano offers a variety of hub dynamos under the "Nexus" brand, such as the DH-3N70/DH-3N71, advertised as having significantly less drag than the Nexus NX-30.
SRAM manufactured the i-Light hub dynamo until 2017. The D7 series was available for both rim and disc brakes while the D3 series featured several rim brake varieties. In a 2006 review by the German Stiftung Warentest, the efficiency at of a D1 series i-Light hub dynamo was 66%, 10% better than a SON-28.
SR Suntour offered the DH-CT-630 hub dynamo series with integrated overvoltage protection. It was apparently discontinued in 2010, as it is absent from 2011 and later SR Suntour catalogs.
SP Dynamo Systems offer |
https://en.wikipedia.org/wiki/Error%20threshold%20%28evolution%29 | In evolutionary biology and population genetics, the error threshold (or critical mutation rate) is a limit on the number of base pairs a self-replicating molecule may have before mutation will destroy the information in subsequent generations of the molecule. The error threshold is crucial to understanding "Eigen's paradox".
The error threshold is a concept in the origins of life (abiogenesis), in particular of very early life, before the advent of DNA. It is postulated that the first self-replicating molecules might have been small ribozyme-like RNA molecules. These molecules consist of strings of base pairs or "digits", and their order is a code that directs how the molecule interacts with its environment. All replication is subject to mutation error. During the replication process, each digit has a certain probability of being replaced by some other digit, which changes the way the molecule interacts with its environment, and may increase or decrease its fitness, or ability to reproduce, in that environment.
Fitness landscape
It was noted by Manfred Eigen in his 1971 paper (Eigen 1971) that this mutation process places a limit on the number of digits a molecule may have. If a molecule exceeds this critical size, the effect of the mutations becomes overwhelming and a runaway mutation process will destroy the information in subsequent generations of the molecule. The error threshold is also controlled by the "fitness landscape" for the molecules. The fitness landscape is characterized by the two concepts of height (=fitness) and distance (=number of mutations). Similar molecules are "close" to each other, and molecules that are fitter than others and more likely to reproduce, are "higher" in the landscape.
If a particular sequence and its neighbors have a high fitness, they will form a quasispecies and will be able to support longer sequence lengths than a fit sequence with few fit neighbors, or a less fit neighborhood of sequences. Also, it was noted by Wi |
https://en.wikipedia.org/wiki/Dissection%20problem | In geometry, a dissection problem is the problem of partitioning a geometric figure (such as a polytope or ball) into smaller pieces that may be rearranged into a new figure of equal content. In this context, the partitioning is called simply a dissection (of one polytope into another). It is usually required that the dissection use only a finite number of pieces. Additionally, to avoid set-theoretic issues related to the Banach–Tarski paradox and Tarski's circle-squaring problem, the pieces are typically required to be well-behaved. For instance, they may be restricted to being the closures of disjoint open sets.
The Bolyai–Gerwien theorem states that any polygon may be dissected into any other polygon of the same area, using interior-disjoint polygonal pieces. It is not true, however, that any polyhedron has a dissection into any other polyhedron of the same volume using polyhedral pieces (see Dehn invariant). This process is possible, however, for any two honeycombs (such as cube) in three dimension and any two zonohedra of equal volume (in any dimension).
A partition into triangles of equal area is called an equidissection. Most polygons cannot be equidissected, and those that can often have restrictions on the possible numbers of triangles. For example, Monsky's theorem states that there is no odd equidissection of a square.
See also
Dissection puzzle
Hilbert's third problem
Hinged dissection |
https://en.wikipedia.org/wiki/NEC%20V25 | The NEC V25 (μPD70320) is the microcontroller version of the NEC V20 processor, manufactured by NEC Corporation. Features include:
NEC V20 core: 8-bit external data path, 20-bit address bus, machine code compatible with the Intel 8088
Timers
Internal interrupt controller
Dual-channel UART and baud rate generator for serial communications
It was officially phased out by NEC in early 2003. |
https://en.wikipedia.org/wiki/Snedding | Snedding is the process of stripping the side shoots and buds from the length of a branch or shoot, usually of a tree or woody shrub. This process is most commonly performed during hedge laying and prior to the felling of trees on plantations ready for cropping.
The verb 'sned', analogous to today's limbing, has also been used by woodcutters in Scotland to refer to the process of removing branches from felled trees. Whether using an axe, a chainsaw or a billhook, the relative difficulty of snedding was a key measure of the difficulty of the job as a whole.
The word comes from the Scandinavian snäddare, meaning a smooth log via the Old English snǣdan.
Snedding can also describe a form of pruning when only some shoots will be removed, or when removing the leafy top from root crops (particularly turnips). |
https://en.wikipedia.org/wiki/Eva%20%28social%20network%29 | eva is a video social network that allows users to record and post short, spontaneous videos from their mobile phones.
Overview
eva is a mobile app and social networking service that was launched by Forbidden Technologies plc - creator of cloud-based video editing software FORscene - in summer 2015. Its co-founders include Stephen B. Streater (founder of Eidos Interactive), Aziz Musa (CEO of Forbidden Technologies plc) and Jens Wikholm (award-winning celebrity and portrait photographer). After holding the beta launch in London in July 2015 - and a subsequent regional launch in Melbourne - eva launched globally in Los Angeles on 1 October 2015. It is available on iOS and can be downloaded from the App Store.
Using eva
In order to make a video on eva, a user simply holds their thumb on the in-app record button and releases it when they are finished. The videos that users take are then automatically uploaded to their personal feed, the wider eva public feed, and grouped by interest topic so they directly become a part of the right communities. Instead of being saved to users' phones, these videos are saved in the cloud, utilising the powerful cloud-based video editing software developed by FORscene. eva has been described by SourceWire as "beautiful, simple and addictive".
Press Coverage
Working with service design consultancy we are experience (or wae), eva's initial structure was created and launched in an incredible 30-day sprint that made waves in the press.
In autumn 2015, eva - working with Chameleon PR - funded research into stereotypes surrounding bearded men, a piece of research that was picked up by over 100 global publications including the Huffington Post, the Independent, and Cosmopolitan (magazine). |
https://en.wikipedia.org/wiki/James%20Wallace%20Black | James Wallace Black (February 10, 1825 – January 5, 1896), known professionally as J.W. Black, was an early American photographer whose career was marked by experimentation and innovation.
Biography
He was born on February 10, 1825, in Francestown, New Hampshire.
After trying his luck as a painter in Boston, he turned to photography, beginning as a daguerreotype plate polisher. He soon partnered with John Adams Whipple, a prolific Boston photographer and inventor. Black's photograph of abolitionist John Brown in 1859, the year of his insurrection at Harpers Ferry, is now in the National Portrait Gallery, Smithsonian Institution.
In March 1860, Black took a photograph of poet Walt Whitman when Whitman was in Boston to oversee the typesetting of his 1860 edition of Leaves of Grass. Black's studio at 173 Washington Street was less than a block from the publishing firm of Thayer and Eldridge, who apparently commissioned the photograph to promote the 1860 edition.
On October 13, 1860, two years after the French photographer Nadar conducted his earliest experiments in balloon flight, Black made the first successful aerial photographs in the United States in collaboration with the balloon navigator Samuel Archer King on King's hot-air balloon, the Queen of the Air. He photographed Boston from a hot-air balloon at , taking 8 plates of glass negative measuring . One good print resulted, which the photographer entitled Boston, as the Eagle and the Wild Goose See It. This was the first clear aerial image of a city.
Almost immediately, aerial reconnaissance would be put to use by the Union and Confederate Armies during the American Civil War, though there is no credible evidence that aerial photography was successful.
Black later became the authority on the use of the magic lantern, a candlelight-powered projector that was a predecessor of today's slide projectors. By the late 1870s Black's business largely consisted of lantern slide production, including his famous imag |
https://en.wikipedia.org/wiki/Force%20field%20%28physics%29 | In physics, a force field is a vector field corresponding with a non-contact force acting on a particle at various positions in space. Specifically, a force field is a vector field , where is the force that a particle would feel if it were at the point .
Examples
Gravity is the force of attraction between two objects. A gravitational force field models this influence that a massive body (or more generally, any quantity of energy) extends into the space around itself. In Newtonian gravity, a particle of mass M creates a gravitational field , where the radial unit vector points away from the particle. The gravitational force experienced by a particle of light mass m, close to the surface of Earth is given by , where g is Earth's gravity.
An electric field exerts a force on a point charge q, given by .
In a magnetic field , a point charge moving through it experiences a force perpendicular to its own velocity and to the direction of the field, following the relation: .
Work
Work is dependent on the displacement as well as the force acting on an object. As a particle moves through a force field along a path C, the work done by the force is a line integral:
This value is independent of the velocity/momentum that the particle travels along the path.
Conservative force field
For a conservative force field, it is also independent of the path itself, depending only on the starting and ending points. Therefore, the work for an object travelling in a closed path is zero, since its starting and ending points are the same:
If the field is conservative, the work done can be more easily evaluated by realizing that a conservative vector field can be written as the gradient of some scalar potential function:
The work done is then simply the difference in the value of this potential in the starting and end points of the path. If these points are given by x = a and x = b, respectively:
See also
Classical mechanics
Field line
Force
Mechanical work |
https://en.wikipedia.org/wiki/Force%20field%20%28chemistry%29 | In the context of chemistry and molecular modelling, a force field is a computational method that is used to estimate the forces between atoms within molecules and also between molecules. More precisely, the force field refers to the functional form and parameter sets used to calculate the potential energy of a system of atoms or coarse-grained particles in molecular mechanics, molecular dynamics, or Monte Carlo simulations. The parameters for a chosen energy function may be derived from experiments in physics and chemistry, calculations in quantum mechanics, or both. Force fields are interatomic potentials and utilize the same concept as force fields in classical physics, with the difference that the force field parameters in chemistry describe the energy landscape, from which the acting forces on every particle are derived as a gradient of the potential energy with respect to the particle coordinates.
All-atom force fields provide parameters for every type of atom in a system, including hydrogen, while united-atom interatomic potentials treat the hydrogen and carbon atoms in methyl groups and methylene bridges as one interaction center. Coarse-grained potentials, which are often used in long-time simulations of macromolecules such as proteins, nucleic acids, and multi-component complexes, sacrifice chemical details for higher computing efficiency.
Functional form
The basic functional form of potential energy in molecular mechanics includes bonded terms for interactions of atoms that are linked by covalent bonds, and nonbonded (also termed noncovalent) terms that describe the long-range electrostatic and van der Waals forces. The specific decomposition of the terms depends on the force field, but a general form for the total energy in an additive force field can be written as
where the components of the covalent and noncovalent contributions are given by the following summations:
The bond and angle terms are usually modeled by quadratic energy functions that d |
https://en.wikipedia.org/wiki/Ion%20mobility%20spectrometry | Ion mobility spectrometry (IMS) It is a method of conducting analytical research that separates and identifies ionized molecules present in the gas phase based on the mobility of the molecules in a carrier buffer gas. Even though it is used extensively for military or security objectives, such as detecting drugs and explosives, the technology also has many applications in laboratory analysis, including studying small and big biomolecules. IMS instruments are extremely sensitive stand-alone devices, but are often coupled with mass spectrometry, gas chromatography or high-performance liquid chromatography in order to achieve a multi-dimensional separation. They come in various sizes, ranging from a few millimeters to several meters depending on the specific application, and are capable of operating under a broad range of conditions. IMS instruments such as microscale high-field asymmetric-waveform ion mobility spectrometry can be palm-portable for use in a range of applications including volatile organic compound (VOC) monitoring, biological sample analysis, medical diagnosis and food quality monitoring. Systems operated at higher pressure (i.e. atmospheric conditions, 1 atm or 1013 hPa) are often accompanied by elevated temperature (above 100 °C), while lower pressure systems (1-20 hPa) do not require heating.
History
IMS was first developed primarily by Earl W. McDaniel of Georgia Institute of Technology in the 1950s and 1960s when he used drift cells with low applied electric fields to study gas phase ion mobilities and reactions. In the following decades, he integrated the recently developed technology he had been working on with a magnetic-sector mass spectrometer. During this period, others also utilized his techniques in novel and original ways. Since then, IMS cells have been included in various configurations of mass spectrometers, gas chromatographs, and high-performance liquid chromatography instruments. IMS is a method used in multiple contexts, and the b |
https://en.wikipedia.org/wiki/Marcel%20Vogel | Marcel Joseph Vogel (April 14, 1917 – February 12, 1991) was a research scientist working at the IBM San Jose Research Center for 27 years. He is sometimes referred to as Dr. Vogel, although this title was based on an honorary degree, not a Ph.D. Later in his career, he became interested in various theories of quartz crystals and other occult and esoteric fields of study.
Mainstream scientific work
It is claimed that Vogel started his research into luminescence while he was still in his teens. This research eventually led him to publish his thesis, Luminescence in Liquids and Solids and Their Practical Application, in collaboration with University of Chicago's Dr. Peter Pringsheim in 1943.
Two years after the publication, Vogel incorporated his own company, Vogel Luminescence, in San Francisco. For the next decade the firm developed a variety of new products: fluorescent crayons, tags for insecticides, a black light inspection kit to determine the secret trackways of rodents in cellars from their urine and the psychedelic colors popular in "new age" posters. In 1957, Vogel Luminescence was sold to Ultra Violet Products and Vogel joined IBM as a full-time research scientist. He retired from IBM in 1984.
In 1977 and 1978, Vogel participated in experiments with the Markovich Tesla Electrical Power Source, referred to as MTEPS, that was built by Peter T. Markovich.
He received 32 patents for his inventions up through his tenure at IBM. Among these was the magnetic coating for the 24" hard disk drive systems still in use. His areas of expertise, besides luminescence, were phosphor technology, magnetics and liquid crystal systems.
At Vogel's February 14, 1991 funeral, IBM researcher and Sacramento, California physician Bernard McGinity, M.D. said of him, "He made his mark because of the brilliance of his mind, his prolific ideas, and his seemingly limitless creativity."
Esoteric and occult studies
Crystals
Vogel was a proponent of crystal healing, and believed cut |
https://en.wikipedia.org/wiki/Commodore%20LCD | The Commodore LCD (sometimes known in short as the CLCD) is an LCD-equipped laptop made by Commodore International. It was presented at the January 1985 Consumer Electronics Show, but never released. The CLCD was not directly compatible with other Commodore home computers, but its built-in Commodore BASIC 3.6 interpreter could run programs written in the Commodore 128's BASIC 7.0, as long as these programs did not include system-specific POKE commands. Like the Commodore 264 and Radio Shack TRS-80 Model 100 series computers, the CLCD had several built-in ROM-based office application programs.
The CLCD featured a 1 MHz Rockwell 65C102 CPU (a CMOS 6502 variant) and 32 KB of RAM (expandable to 64 KB internally). The BASIC interpreter and application programs were built into 96 KB of ROM. |
https://en.wikipedia.org/wiki/Roy%27s%20identity | Roy's identity (named after French economist René Roy) is a major result in microeconomics having applications in consumer choice and the theory of the firm. The lemma relates the ordinary (Marshallian) demand function to the derivatives of the indirect utility function. Specifically, denoting the indirect utility function as the Marshallian demand function for good can be calculated as
where is the price vector of goods and is income, and where the superscript indicates Marshallian demand. The result holds for continuous utility functions representing locally non-satiated and strictly convex preference relations on a convex consumption set, under the additional requirement that the indirect utility function is differentiable in all arguments.
Roy's identity is akin to the result that the price derivatives of the expenditure function give the Hicksian demand functions. The additional step of dividing by the wealth derivative of the indirect utility function in Roy's identity is necessary since the indirect utility function, unlike the expenditure function, has an ordinal interpretation: any strictly increasing transformation of the original utility function represents the same preferences.
Derivation of Roy's identity
Roy's identity reformulates Shephard's lemma in order to get a Marshallian demand function for an individual and a good () from some indirect utility function.
The first step is to consider the trivial identity obtained by substituting the expenditure function for wealth or income in the indirect utility function , at a utility of :
This says that the indirect utility function evaluated in such a way that minimizes the cost for achieving a certain utility given a set of prices (a vector ) is equal to that utility when evaluated at those prices.
Taking the derivative of both sides of this equation with respect to the price of a single good (with the utility level held constant) gives:
.
Rearranging gives the desired result:
with the s |
https://en.wikipedia.org/wiki/Spring%20scale | A spring scale, spring balance or newton meter is a type of mechanical force gauge or weighing scale. It consists of a spring fixed at one end with a hook to attach an object at the other. It works in accordance with Hooke's Law, which states that the force needed to extend or compress a spring by some distance scales linearly with respect to that distance. Therefore, the scale markings on the spring balance are equally spaced.
A spring balance can be calibrated for the accurate measurement of mass in the location in which they are used, but many spring balances are marked right on their face "Not Legal for Trade" or words of similar import due to the approximate nature of the theory used to mark the scale. Also, the spring in the scale can permanently stretch with repeated use.
A spring scale will only read correctly in a frame of reference where the acceleration in the spring axis is constant (such as on earth, where the acceleration is due to gravity). This can be shown by taking a spring scale into an elevator, where the weight measured will change as the elevator moves up and down changing velocities.
If two or more spring balances are hung one below the other in series, each of the scales will read approximately the same, the full weight of the body hung on the lower scale. The scale on top would read slightly heavier due to also supporting the weight of the lower scale itself.
Spring balances come in different sizes. Generally, small scales that measure newtons will have a less firm spring (one with a smaller spring constant) than larger ones that measure tens, hundreds or thousands of newtons or even more depending on the scale of newtons used. The largest spring scale ranged in measurement from 5000–8000 newtons.
A spring balance may be labeled in both units of force (poundals, Newtons) and mass (pounds, kilograms/grams). Strictly speaking, only the force values are correctly labeled. In order to infer that the labeled mass values are correct, an ob |
https://en.wikipedia.org/wiki/Neurotransmission | Neurotransmission (Latin: transmissio "passage, crossing" from transmittere "send, let through") is the process by which signaling molecules called neurotransmitters are released by the axon terminal of a neuron (the presynaptic neuron), and bind to and react with the receptors on the dendrites of another neuron (the postsynaptic neuron) a short distance away. A similar process occurs in retrograde neurotransmission, where the dendrites of the postsynaptic neuron release retrograde neurotransmitters (e.g., endocannabinoids; synthesized in response to a rise in intracellular calcium levels) that signal through receptors that are located on the axon terminal of the presynaptic neuron, mainly at GABAergic and glutamatergic synapses.
Neurotransmission is regulated by several different factors: the availability and rate-of-synthesis of the neurotransmitter, the release of that neurotransmitter, the baseline activity of the postsynaptic cell, the number of available postsynaptic receptors for the neurotransmitter to bind to, and the subsequent removal or deactivation of the neurotransmitter by enzymes or presynaptic reuptake.
In response to a threshold action potential or graded electrical potential, a neurotransmitter is released at the presynaptic terminal. The released neurotransmitter may then move across the synapse to be detected by and bind with receptors in the postsynaptic neuron. Binding of neurotransmitters may influence the postsynaptic neuron in either an inhibitory or excitatory way. The binding of neurotransmitters to receptors in the postsynaptic neuron can trigger either short term changes, such as changes in the membrane potential called postsynaptic potentials, or longer term changes by the activation of signaling cascades.
Neurons form complex biological neural networks through which nerve impulses (action potentials) travel. Neurons do not touch each other (except in the case of an electrical synapse through a gap junction); instead, neurons intera |
https://en.wikipedia.org/wiki/Scientistic%20materialism | Scientistic materialism is a term used mainly by proponents of creationism and intelligent design to describe scientists who have a materialist worldview. The stance has been attributed to philosopher George Santayana.
History
The "Wedge Document" produced by the Discovery Institute, described materialism as denial of "the proposition that human beings are created in the image of God," and that humans are instead "animals or machines who inhabited a universe ruled by purely impersonal forces and whose behavior and very thoughts were dictated by the unbending forces of biology, chemistry and environment." The document states that materialism leads inevitably to "moral relativism" and denounces its "stifling dominance" in modern culture. By this definition, scientific materialism is linked to the more general version of materialism, which declares that the physical world is the only thing that exists and that nothing supernatural exists.
See also
Conflict thesis
Faith and rationality
Mechanistic materialism
Relationship between religion and science
Scientific mythology
Scientism |
https://en.wikipedia.org/wiki/Max%20Planck%20Institute%20for%20Nuclear%20Physics | The Max-Planck-Institut für Kernphysik ("MPI for Nuclear Physics" or MPIK for short) is a
research institute in Heidelberg, Germany.
The institute is one of the 80 institutes of the Max-Planck-Gesellschaft (Max Planck Society), an independent, non-profit research organization. The Max Planck Institute for Nuclear Physics was founded in 1958 under the leadership of Wolfgang Gentner. Its precursor was the Institute for Physics at the MPI for Medical Research.
Today, the institute's research areas are: crossroads of particle physics and astrophysics (astroparticle physics) and many-body dynamics of atoms and molecules (quantum dynamics).
The research field of Astroparticle Physics, represented by the divisions of Jim Hinton, Werner Hofmann and Manfred Lindner, combines questions related to macrocosm and microcosm. Unconventional methods of observation for gamma rays and neutrinos open new windows to the universe. What lies behind “dark matter” and “dark energy” is theoretically investigated.
The research field of Quantum Dynamics is represented by the divisions of Klaus Blaum, Christoph Keitel and Thomas Pfeifer. Using reaction microscopes, simple chemical reactions can be “filmed”. Storage rings and traps allow precision experiments almost under space conditions. The interaction of intense laser light with matter is investigated using quantum-theoretical methods.
Further research fields are cosmic dust, atmospheric physics as well as fullerenes and other carbon molecules.
Scientists at the MPIK collaborate with other research groups in Europe and all over the world and are involved in numerous international collaborations, partly in a leading role. Particularly close connections to some large-scale facilities like GSI (Darmstadt), DESY (Hamburg), CERN (Geneva), TRIUMF (Canada), and INFN-LNGS (Assergi L‘Aquila) exist. The institute has about 390 employees, as well as many diploma students and scientific guests.
In the local region, the Institute cooperates clos |
https://en.wikipedia.org/wiki/Blood%20in%20stool | Blood in stool or rectal bleeding looks different depending on how early it enters the digestive tract—and thus how much digestive action it has been exposed to—and how much there is. The term can refer either to melena, with a black appearance, typically originating from upper gastrointestinal bleeding; or to hematochezia, with a red color, typically originating from lower gastrointestinal bleeding. Evaluation of the blood found in stool depends on its characteristics, in terms of color, quantity and other features, which can point to its source, however, more serious conditions can present with a mixed picture, or with the form of bleeding that is found in another section of the tract. The term "blood in stool" is usually only used to describe visible blood, and not fecal occult blood, which is found only after physical examination and chemical laboratory testing.
In infants, the Apt test can be used to distinguish fetal hemoglobin from maternal blood based on the differences in composition of fetal hemoglobin as compared to the hemoglobin found in adults.
Differential diagnoses
Blood in the stool can come from many sources. The causes range from not harmful to very serious conditions. A common way to divide causes of bleeding is based on the source of bleeding. The GI tract can be divided into upper and lower, with some causes of bleeding affecting the entire tract (upper and lower). Blood in the stool often appears different depending on its source. These differences can help when diagnosing these conditions. The rate of bleeding can also make blood in the stool look different from typical cases.
Upper GI tract
The upper GI tract is defined as the organs involved in digestion above the ligament of Treitz and comprises the esophagus, stomach, and duodenum. Upper gastrointestinal bleeding is typically characterized by melena (black stool). Bright red blood may be seen with active, rapid bleeding.
Pathophysiology
The development of blood in a person's stool r |
https://en.wikipedia.org/wiki/Sativum | Sativa, sativus, and sativum are Latin botanical adjectives meaning cultivated. It is often associated botanically with plants that promote good health and used to designate certain seed-grown domestic crops.
Usage
Sativa (ending in -a) is the feminine form of the adjective, but masculine (-us) and neuter (-um) endings are also used to agree with the gender of the nouns they modify. For example, the masculine Crocus sativus and neuter Pisum sativum.
Examples
Examples of crops incorporating this word and its variations into their Latin name include:
Allium sativum, garlic.
Avena sativa, the common oat.
Cannabis sativa, one of three forms of cannabis.
Castanea sativa, sweet chestnut.
Crocus sativus, the saffron crocus.
Cucumis sativus, the cucumber.
Daucus carota subsp. sativus, the carrot, a plant species.
Eruca sativa, the rocket or arugula, a leaf vegetable.
Lactuca sativa, Lollo rosso lettuce.
Medicago sativa, alfalfa.
Nigella sativa, a flower whose edible seeds are sometimes known as "black cumin" or "black caraway".
Oryza sativa, rice.Pastinaca sativa., parsnip, a root vegetable closely related to the carrot and parsley; all belong to the family Apiaceae.
Pisum sativum'', pea plant.
See also
8 Foot Sativa, a New Zealand–based metal band
Sativa (Jhené Aiko song)
Sativanorte and Sativasur, towns/municipalities in the Colombian department of Boyacá
Sativum (disambiguation)
Sativus (disambiguation) |
https://en.wikipedia.org/wiki/Magnetospirillum | Magnetospirillum is a Gram-negative, microaerophilic genus of magnetotactic bacteria, first isolated from pond water by the microbiologist R. P. Blakemore in 1975. They have a spiral (helical) shape and are propelled by a polar flagellum at each end of their cells. Four species have been described: M. magnetotacticum strain MS-1 (originally classified as Aquaspirillum magnetotacticum; M. magneticum strain AMB-1; M. gryphiswaldense and M. bellicus.
Habitat
The typical habitat of Magnetospirillum species consists of shallow fresh water and sediments, characterized by low concentrations of oxygen for growth (microaerophilic) where they live in the upper portion of the sediment (oxic/anoxic interface) and prefer an oxygen gradient of around 1–3%.
Magnetotaxis
Probably the most peculiar characteristic of Magnetospirillum species is their capacity to orient themselves according to Earth's magnetic field, magnetotaxis. This is achieved through the presence of special organelles called magnetosomes in the bacterium's cytoplasm. Magnetospirillum species also resort to aerotaxis, to remain in favorable O2 concentration conditions. When the bacteria ingest iron, proteins inside their cells interact with it to produce tiny crystals of the mineral magnetite, the most magnetic mineral on Earth.
Purification of magnetosomes is accomplished by use of a magnetic separation column after disruption of the cell membrane. If a detergent is used on purified magnetosomes, they tend to agglomerate rather than staying in chain form. Due to the high quality of the single-domain magnetic crystals, a commercial interest has developed in the bacteria. The crystals are thought to have the potential to produce magnetic tapes and magnetic target drugs.
Species
Magnetospirillum bellicus
Magnetospirillum caucaseum
Magnetospirillum gryphiswaldense
Magnetospirillum magnetotacticum—isolated from microaerobic zones of freshwater sediments. Differing from other chemoheterotrophs; the bacterium |
https://en.wikipedia.org/wiki/Neuronal%20tuning | Neuronal tuning refers to the hypothesized property of brain cells by which they selectively represent a particular type of sensory, association, motor, or cognitive information. Some neuronal responses have been hypothesized to be optimally tuned to specific patterns through experience. Neuronal tuning can be strong and sharp, as observed in primary visual cortex (area V1) (but see Carandini et al 2005 ), or weak and broad, as observed in neural ensembles. Single neurons are hypothesized to be simultaneously tuned to several modalities, such as visual, auditory, and olfactory. Neurons hypothesized to be tuned to different signals are often hypothesized to integrate information from the different sources. In computational models called neural networks, such integration is the major principle of operation. The best examples of neuronal tuning can be seen in the visual, auditory, olfactory, somatosensory, and memory systems, although due to the small number of stimuli tested the generality of neuronal tuning claims is still an open question.
Visually Tuned System
Accepted neuronal tuning models suggest that neurons respond to different degrees based on the similarity between the optimal stimulus of the neuron and the given stimulus. (Teller (1984), however, has challenged the "detector" view of neurons on logical grounds) The first major evidence of neuronal tuning in the visual system was provided by Hubel and Wiesel in 1959. They discovered that oriented slits of light were the most effective (of a very small set tested) stimuli for striate cortex “simple cell” neurons. Other neurons, “complex cells," responded best to lines of a certain orientation moving in a specific direction. Overall, the V1 neurons were found to be selectively tuned to certain orientations, sizes, positions, and forms. Hubel and Wiesel won the Nobel Prize in Physiology or Medicine in 1981 for their discoveries concerning information processing in the visual system. (More recently, Carandini |
https://en.wikipedia.org/wiki/Icebox | An icebox (also called a cold closet) is a compact non-mechanical refrigerator which was a common early-twentieth-century kitchen appliance before the development of safely powered refrigeration devices. Before the development of electric refrigerators, iceboxes were referred to by the public as "refrigerators". Only after the invention of the modern electric refrigerator did early non-electric refrigerators become known as iceboxes. The terms ice box and refrigerator were used interchangeably in advertising as long ago as 1848.
Origin
The first recorded use of refrigeration technology dates back to 1775 BC in the Sumerian city of Terqa. It was there that the region's King, Zimri-lim, began the construction of an elaborate ice house fitted with a sophisticated drainage system and shallow pools to freeze water in the night. Using ice for cooling and preservation was nothing new by then, but these ice houses paved the way for their smaller counterpart, the icebox, to come into existence. The traditional kitchen icebox dates back to the days of ice harvesting, whose heyday ran from the mid-19th century until the 1930s, when the electric refrigerator was introduced for home use. Most municipally consumed ice was harvested in winter from snow-packed areas or frozen lakes, stored in ice houses, and delivered domestically. In 1827 the commercial ice cutter was invented, increasing the ease and efficiency of harvesting natural ice. This invention made ice cheaper and in turn helped the icebox become more common.
Up until then, iceboxes for domestic use were not mass manufactured. By the 1840s, however, various companies including the Baldwin Refrigerator Company and the Ranney Refrigerator Company, and later Sears, started making home iceboxes commercially. D. Eddy & Son of Boston is considered to be the first company to produce iceboxes in mass numbers. As many Americans desired big iceboxes, some companies, such as the Boston Scientific Refrigerator Company, introduc |
https://en.wikipedia.org/wiki/Zope%20Object%20Database | The Zope Object Database (ZODB) is an object-oriented database for transparently and persistently storing Python objects. It is included as part of the Zope web application server, but can also be used independently of Zope.
Features of the ZODB include: transactions, history/undo, transparently pluggable storage, built-in caching, multiversion concurrency control (MVCC), and scalability across a network (using ).
History
Created by Jim Fulton of Zope Corporation in the late 90s.
Started as simple Persistent Object System (POS) during Principia development (which later became Zope)
ZODB 3 was renamed when a significant architecture change was landed.
ZODB 4 was a short lived project to re-implement the entire ZODB 3 package using 100% Python.
Implementation
Basics
ZODB stores Python objects using an extended version of Python's built-in object persistence (pickle). A ZODB database has a single root object (normally a dictionary), which is the only object directly made accessible by the database. All other objects stored in the database are reached through the root object. Objects referenced by an object stored in the database are automatically stored in the database as well.
ZODB supports concurrent transactions using MVCC and tracks changes to objects on a per-object basis. Only changed objects are committed. Transactions are non-destructive by default and can be reverted.
Example
For example, say we have a car described using 3 classes Car, Wheel and Screw. In Python, this could be represented the following way:
class Car: [...]
class Wheel: [...]
class Screw: [...]
myCar = Car()
myCar.wheel1 = Wheel()
myCar.wheel2 = Wheel()
for wheel in (myCar.wheel1, myCar.wheel2):
wheel.screws = [Screw(), Screw()]
If the variable mycar is the root of persistence, then:
zodb['mycar'] = myCar
This puts all of the object instances (car, wheel, screws etc.) into storage, which can be retrieved later. If another program gets a connection to the database through the |
https://en.wikipedia.org/wiki/Born%20rigidity | Born rigidity is a concept in special relativity. It is one answer to the question of what, in special relativity, corresponds to the rigid body of non-relativistic classical mechanics.
The concept was introduced by Max Born (1909), who gave a detailed description of the case of constant proper acceleration which he called hyperbolic motion. When subsequent authors such as Paul Ehrenfest (1909) tried to incorporate rotational motions as well, it became clear that Born rigidity is a very restrictive sense of rigidity, leading to the Herglotz–Noether theorem, according to which there are severe restrictions on rotational Born rigid motions. It was formulated by Gustav Herglotz (1909, who classified all forms of rotational motions) and in a less general way by Fritz Noether (1909). As a result, Born (1910) and others gave alternative, less restrictive definitions of rigidity.
Definition
Born rigidity is satisfied if the orthogonal spacetime distance between infinitesimally separated curves or worldlines is constant, or equivalently, if the length of the rigid body in momentary co-moving inertial frames measured by standard measuring rods (i.e. the proper length) is constant and is therefore subjected to Lorentz contraction in relatively moving frames. Born rigidity is a constraint on the motion of an extended body, achieved by careful application of forces to different parts of the body. A body rigid in itself would violate special relativity, as its speed of sound would be infinite.
A classification of all possible Born rigid motions can be obtained using the Herglotz–Noether theorem. This theorem states, that all irrotational Born rigid motions (class A) consist of hyperplanes rigidly moving through spacetime, while any rotational Born rigid motion (class B) must be isometric Killing motions. This implies that a Born rigid body only has three degrees of freedom. Thus a body can be brought in a Born rigid way from rest into any translational motion, but it cannot |
https://en.wikipedia.org/wiki/Pre-order | A pre-order is an order placed for an item that has not yet been released. The idea for pre-orders came because people found it hard to get popular items in stores because of their popularity. Companies then had the idea to allow customers to reserve their own personal copy before its release, which has been a huge success.
Pre-orders allow consumers to guarantee immediate shipment on release, manufacturers can gauge how much demand there will be and thus the size of initial production runs, and sellers can be assured of minimum sales. Additionally, high pre-order rates can be used to increase sales further.
Pre-order incentive
Pre-order incentive, also known as pre-order bonus, is a marketing tactic in which a retailer or manufacturer/publisher of a product (usually a book or video game) encourages buyers to reserve a copy of the product at the store prior to its release.
Reasons vary, but typically, publishers wish to ensure strong initial sales for a product, and the offered incentive is used to induce shoppers who might otherwise wait for positive reviews or a specific shopping period, like the holiday season, to commit to a purchase. Having paid for part or all of the purchase when placing the order, the consumers will usually complete the transaction shortly after the product's release, often on its first day in stores. Individual stores or retail chains may also offer bonuses for a popularly anticipated product to ensure that the customer chooses to buy at that location, rather than from a competitor.
The pre-order bonus may be as simple as a discount on the item's purchase price or other related merchandise, another marketing strategy, or it may be an actual item or set of items. The items may be related merchandise or exclusive items available only through the pre-order program.
In video games
Until around 2000, the primary distribution method for video games were through physical media such as CD-ROMs, DVDs, or game cartridges, including packaging an |
https://en.wikipedia.org/wiki/List%20of%20combinatorial%20computational%20geometry%20topics | List of combinatorial computational geometry topics enumerates the topics of computational geometry that states problems in terms of geometric objects as discrete entities and hence the methods of their solution are mostly theories and algorithms of combinatorial character.
See List of numerical computational geometry topics for another flavor of computational geometry that deals with geometric objects as continuous entities and applies methods and algorithms of nature characteristic to numerical analysis.
Construction/representation
Boolean operations on polygons
Convex hull
Hyperplane arrangement
Polygon decomposition
Polygon triangulation
Minimal convex decomposition
Minimal convex cover problem (NP-hard)
Minimal rectangular decomposition
Tessellation problems
Shape dissection problems
Straight skeleton
Stabbing line problem
Triangulation
Delaunay triangulation
Point-set triangulation
Polygon triangulation
Voronoi diagram
Extremal shapes
Minimum bounding box (Smallest enclosing box, Smallest bounding box)
2-D case: Smallest bounding rectangle (Smallest enclosing rectangle)
There are two common variants of this problem.
In many areas of computer graphics, the bounding box (often abbreviated to bbox) is understood to be the smallest box delimited by sides parallel to coordinate axes which encloses the objects in question.
In other applications, such as packaging, the problem is to find the smallest box the object (or objects) may fit in ("packaged"). Here the box may assume an arbitrary orientation with respect to the "packaged" objects.
Smallest bounding sphere (Smallest enclosing sphere)
2-D case: Smallest bounding circle
Largest empty rectangle (Maximum empty rectangle)
Largest empty sphere
2-D case: Maximum empty circle (largest empty circle)
Interaction/search
Collision detection
Line segment intersection
Point location
Point in polygon
Polygon intersection
Range searching
Orthogonal range searching
Simplex range searchi |
https://en.wikipedia.org/wiki/Uncorrelated%20asymmetry | In game theory an uncorrelated asymmetry is an arbitrary asymmetry in a game which is otherwise symmetrical. The name 'uncorrelated asymmetry' is due to John Maynard Smith who called payoff relevant asymmetries in games with similar roles for each player 'correlated asymmetries' (note that any game with correlated asymmetries must also have uncorrelated asymmetries).
The explanation of an uncorrelated asymmetry usually makes reference to "informational asymmetry". Which may confuse some readers, since, games which may have uncorrelated asymmetries are still games of complete information . What differs between the same game with and without an uncorrelated asymmetry is whether the players know which role they have been assigned. If players in a symmetric game know whether they are Player 1, Player 2, etc. (or row vs. column player in a bimatrix game) then an uncorrelated asymmetry exists. If the players do not know which player they are then no uncorrelated asymmetry exists. The information asymmetry is that one player believes he is player 1 and the other believes he is player 2. Therefore, "informational asymmetry" does not refer to knowledge in the sense of an information set in an extensive form game.
The concept of uncorrelated asymmetries is important in determining which Nash equilibria are evolutionarily stable strategies in discoordination games such as the game of chicken. In these games the mixing Nash is the ESS if there is no uncorrelated asymmetry, and the pure conditional Nash equilibria are ESSes when there is an uncorrelated asymmetry.
The usual applied example of an uncorrelated asymmetry is territory ownership in the hawk-dove game. Even if the two players ("owner" and "intruder") have the same payoffs (i.e., the game is payoff symmetric), the territory owner will play Hawk, and the intruder Dove, in what is known as the 'Bourgeois strategy' (the reverse is also an ESS known as the 'anti-bourgeois strategy', but makes little biologi |
https://en.wikipedia.org/wiki/List%20of%20numerical%20computational%20geometry%20topics | List of numerical computational geometry topics enumerates the topics of computational geometry that deals with geometric objects as continuous entities and applies methods and algorithms of nature characteristic to numerical analysis. This area is also called "machine geometry", computer-aided geometric design, and geometric modelling.
See List of combinatorial computational geometry topics for another flavor of computational geometry that states problems in terms of geometric objects as discrete entities and hence the methods of their solution are mostly theories and algorithms of combinatorial character.
Curves
In the list of curves topics, the following ones are fundamental to geometric modelling.
Parametric curve
Bézier curve
Spline
Hermite spline
Beta spline
B-spline
Higher-order spline
NURBS
Contour line
Surfaces
Bézier surface
Isosurface
Parametric surface
Other
Level-set method
Computational topology
Mathematics-related lists
Geometric algorithms
Geometry |
https://en.wikipedia.org/wiki/Busulfan | Busulfan (Myleran, GlaxoSmithKline, Busulfex IV, Otsuka America Pharmaceutical, Inc.) is a chemotherapy drug in use since 1959. It is a cell cycle non-specific alkylating antineoplastic agent, in the class of alkyl sulfonates. Its chemical designation is 1,4-butanediol dimethanesulfonate.
History
Busulfan was approved by the US Food and Drug Administration (FDA) for treatment of chronic myeloid leukemia (CML) in 1999. Busulfan was the mainstay of the chemotherapeutic treatment of chronic myeloid leukemia (CML) until it was displaced by the new gold standard, imatinib, though it is still in use to a degree as a result of the drug's relative low cost.
Indications
Busulfan is used in pediatrics and adults in combination with cyclophosphamide or fludarabine/clofarabine as a conditioning agent prior to bone marrow transplantation, especially in chronic myelogenous leukemia (CML) and other leukemias, lymphomas, and myeloproliferative disorders. Busulfan can control tumor burden but cannot prevent transformation or correct cytogenic abnormalities.
The drug was recently used in a study to examine the role of platelet-transported serotonin in liver regeneration.
Availability
Myleran is supplied in white film coated tablets with 2 mg of busulfan per tablet. After 2002, a great interest has appeared for intravenous presentations of busulfan. Busulfex is supplied as an intravenous solution with 6 mg/ml busulfan. Busulfex has proved equally effective as oral busulfan, with presumedly less toxic side effects. Pharmacokinetic and dynamic studies support this use, that has prompted its usage in transplantation regimes, particularly in frail patients. Fludarabine + busulfan is a typical example of this use.
Side effects
Toxicity may include interstitial pulmonary fibrosis ("busulfan lung"), hyperpigmentation, seizures, hepatic (veno-occlusive disease) (VOD) or sinusoidal obstruction syndrome (SOS), emesis, and wasting syndrome. Busulfan also induces impotence in males (kill |
https://en.wikipedia.org/wiki/Gemtuzumab%20ozogamicin | Gemtuzumab ozogamicin, sold under the brand name Mylotarg, is an antibody-drug conjugate (a drug-linked monoclonal antibody) that is used to treat acute myeloid leukemia.
The most common side effects include infection, febrile neutropenia, decreased appetite, hyperglycemia, mucositis, hypoxia, hemorrhage, increased transaminase, diarrhea, nausea, and hypotension. However, the addition of gemtuzumab ozogamicin to standard chemotherapy regimens does not increase infection rates.
Medical uses
In the United States, gemtuzumab ozogamicin is indicated for newly diagnosed CD33-positive acute myeloid leukemia (AML) for adults and children one month and older and for the treatment of relapsed or refractory CD33-positive AML in adults and children two years and older.
Mechanism
Gemtuzumab is a monoclonal antibody to CD33 linked to a cytotoxic agent from the class of calicheamicins (ozogamicin). CD33 is expressed in most leukemic blast cells but also in normal hematopoietic cells, the intensity diminishing with maturation of stem cells.
History
Gemtuzumab ozogamicin was created in a collaboration between Celltech and Wyeth that began in 1991. The same collaboration later produced inotuzumab ozogamicin. Celltech was acquired by UCB in 2004 and Wyeth was acquired by Pfizer in 2009.
In the United States, it was approved under an accelerated-approval process by the FDA in 2000, for use in patients over the age of 60 with relapsed acute myelogenous leukemia (AML); or those who are not considered candidates for standard chemotherapy.
The accelerated approval was based on the surrogate endpoint of response rate. It was the first antibody-drug conjugate to be approved.
Within the first year after approval, the FDA required a black box warning be added to gemtuzumab packaging. The drug was noted to increase the risk of veno-occlusive disease in the absence of bone marrow transplantation. Later the onset of VOD was shown to occur at increased frequency in gemtuzumab patien |
https://en.wikipedia.org/wiki/Sipser%E2%80%93Lautemann%20theorem | In computational complexity theory, the Sipser–Lautemann theorem or Sipser–Gács–Lautemann theorem states that bounded-error probabilistic polynomial (BPP) time is contained in the polynomial time hierarchy, and more specifically Σ2 ∩ Π2.
In 1983, Michael Sipser showed that BPP is contained in the polynomial time hierarchy. Péter Gács showed that BPP is actually contained in Σ2 ∩ Π2. Clemens Lautemann contributed by giving a simple proof of BPP’s membership in Σ2 ∩ Π2, also in 1983. It is conjectured that in fact BPP=P, which is a much stronger statement than the Sipser–Lautemann theorem.
Proof
Here we present the Lautemann's proof. Without loss of generality, a machine M ∈ BPP with error ≤ 2−|x| can be chosen. (All BPP problems can be amplified to reduce the error probability exponentially.) The basic idea of the proof is to define a Σ2 sentence that is equivalent to stating that x is in the language, L, defined by M by using a set of transforms of the random variable inputs.
Since the output of M depends on random input, as well as the input x, it is useful to define which random strings produce the correct output as A(x) = {r | M(x,r) accepts}. The key to the proof is to note that when x ∈ L, A(x) is very large and when x ∉ L, A(x) is very small. By using bitwise parity, ⊕, a set of transforms can be defined as A(x) ⊕ t={r ⊕ t | r ∈ A(x)}. The first main lemma of the proof shows that the union of a small finite number of these transforms will contain the entire space of random input strings. Using this fact, a Σ2 sentence and a Π2 sentence can be generated that is true if and only if x ∈ L (see conclusion).
Lemma 1
The general idea of lemma one is to prove that if A(x) covers a large part of the random space then there exists a small set of translations that will cover the entire random space. In more mathematical language:
If , then , where such that
Proof. Randomly pick t1, t2, ..., t|r|. Let (the union of all transforms of A(x)).
So, for all r |
https://en.wikipedia.org/wiki/Michael%20D.%20Morley | Michael Darwin Morley (September 29, 1930 – October 11, 2020) was an American mathematician. At his death in 2020, Morley was professor emeritus at Cornell University. His research was in mathematical logic and model theory, and he is best known for Morley's categoricity theorem, which he proved in his PhD thesis Categoricity in Power in 1962.
Early life and education
Morley was born in Youngstown, Ohio, on September 29, 1930. He obtained his BS in mathematics from Case Institute of Technology in 1951 and his PhD in mathematics from the University of Chicago in 1962. Morley's formal PhD advisor at the University of Chicago was Saunders Mac Lane, but he completed his thesis under the guidance of Robert Vaught at the University of California, Berkeley. His dissertation was titled Categoricity in Power.
Career
Morley was an assistant professor at the University of Wisconsin–Madison from 1963 to 1967. He joined the faculty at Cornell University in 1967 as an associate professor, was promoted to professor in 1970, and became a professor emeritus in 2003. He served as president of the Association for Symbolic Logic from 1986 to 1989.
Morley received the 2003 Leroy P. Steele Prize for Seminal Contribution to Research from the American Mathematical Society for his 1965 paper "Categoricity in Power". This paper, his doctoral dissertation, introduced Morley rank and proved Morley's categoricity theorem.
Personal life
Morley died on October 11, 2020, in Sayre, Pennsylvania.
Selected publications
See also
Morley's problem |
https://en.wikipedia.org/wiki/Niclosamide | Niclosamide, sold under the brand name Niclocide among others, is an anthelmintic medication used to treat tapeworm infestations, including diphyllobothriasis, hymenolepiasis, and taeniasis. It is not effective against other worms such as flukes or roundworms. It is taken by mouth.
Side effects include nausea, vomiting, abdominal pain, and itchiness. It may be used during pregnancy. It works by blocking glucose uptake and oxidative phosphorylation by the worm.
Niclosamide was first synthesized in 1958. It is on the World Health Organization's List of Essential Medicines. Niclosamide is not available for human use in the United States.
Side effects
Side effects include nausea, vomiting, abdominal pain, constipation, and itchiness. Rarely, dizziness, skin rash, drowsiness, perianal itching, or an unpleasant taste occur. For some of these reasons, praziquantel is a preferable and equally effective treatment for tapeworm infestation.
Important Note: Niclosamide kills the pork tapeworm and results in its digestion. This then may cause a multitude of viable eggs to be released and may result in cysticercosis. Therefore, a purge should be given 1 or two hours after treatment. CNS cysticercosis is a life-threatening condition and may require brain surgery.
Mechanism of action
Niclosamide inhibits glucose uptake, oxidative phosphorylation, and anaerobic metabolism in the tapeworm.
Other applications
Niclosamide's metabolic effects are relevant to a wide ranges of organisms, and accordingly it has been applied as a control measure to organisms other than tapeworms. For example, it is an active ingredient in some formulations such as Bayluscide for killing lamprey larvae, as a molluscide, and as a general purpose piscicide in aquaculture. Niclosamide has a short half-life in water in field conditions; this makes it valuable in ridding commercial fish ponds of unwanted fish; it loses its activity soon enough to permit re-stocking within a few days of eradicating the prev |
https://en.wikipedia.org/wiki/Sunflower%20oil | Sunflower oil is the non-volatile oil pressed from the seeds of the sunflower (Helianthus annuus). Sunflower oil is commonly used in food as a frying oil, and in cosmetic formulations as an emollient.
Sunflower oil is primarily composed of linoleic acid, a polyunsaturated fat, and oleic acid, a monounsaturated fat. Through selective breeding and manufacturing processes, oils of differing proportions of the fatty acids are produced. The expressed oil has a neutral taste profile. The oil contains a large amount of vitamin E.
As of 2017, genome analysis and development of hybrid sunflowers to increase oil production are under development to meet greater consumer demand for sunflower oil and its commercial varieties.
In 2018, Ukraine and Russia together accounted for 53% of the world's production of sunflower oil.
Composition
Sunflower oil is mainly a triglyceride. The British Pharmacopoeia lists the following profile:
Palmitic acid (saturated): 5%
Stearic acid (saturated): 6%
Oleic acid (monounsaturated omega-9): 30%
Linoleic acid (polyunsaturated omega-6): 59%
Four types of sunflower oils with differing concentrations of fatty acids are produced through plant breeding and industrial processing: high-linoleic, high-oleic, mid-oleic, and high-stearic combined with high-oleic.
High-linoleic, 69% linoleic acid
High-oleic, 82% oleic acid
Mid-oleic, 65% oleic acid
High-stearic with high-oleic, 18% stearic acid and 72% oleic acid
In an analysis of the sunflower genome to reveal plant metabolism producing its oil, phytosterols were identified, as confirmed in another analysis of sunflower oil components, including polyphenols, squalene, and terpenoids.
Production
In 2018, world production of sunflower oil was 18million tonnes, led by Ukraine and Russia, which together account for 53% of the world total.
In 2022, there is a global shortage of sunflower oil due to the 2022 Russian invasion of Ukraine, which has led to an over 50% drop in the availability of sunflower |
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