source stringlengths 31 227 | text stringlengths 9 2k |
|---|---|
https://en.wikipedia.org/wiki/Bogart%E2%80%93Bacall%20syndrome | Bogart–Bacall syndrome (BBS) is a voice disorder that is caused by abuse or overuse of the vocal cords.
People who speak or sing outside their normal vocal range can develop BBS; symptoms are chiefly an unusually deep or rough voice, or dysphonia, and vocal fatigue. The people most commonly affected are those who speak in a low-pitched voice, particularly if they have poor breath and vocal control. The syndrome can affect both men and women.
In 1988, an article was published describing a discrete type of vocal dysfunction which results in men sounding like actor Humphrey Bogart and women sounding like actress Lauren Bacall; Bogart and Bacall were married to each other and made several films together. BBS is now the medical term for an ongoing hoarseness that often affects actors, singers or TV/radio voice workers who routinely speak in a very low pitch.
Treatment usually involves voice therapy by a speech language pathologist.
Signs and symptoms
Signs and symptoms of Bogart–Bacall Syndrome can appear differently depending on the vocal use of the individual. In singers, symptoms may appear more subtly due to their extreme sensitivity to small changes in the laryngeal mechanism and being able to control their laryngeal muscles more than the average person. This vocal control can compensate for irritation, weakness, or change in vibration patterns for the vocal folds. Signs and symptoms will vary on a case-by-case basis and will depend on vocal strain and the degree of daily use. Women are also more susceptible than men to experience heightened symptoms due to their increased likelihood of speaking at a lower pitch in professional settings.
Signs and symptoms of Bogart–Bacall include the following:
Vocal fatigue
Unnaturally deep or rough voice
Hoarseness
Sore larynx (tightness or muscle aches in the throat)
Sudden breaks or fading of the voice
Loss of vocal range when singing
Feeling the need to clear the throat often
Experiencing loss of speech
Cause
The |
https://en.wikipedia.org/wiki/Alternative%20frequency | Alternative frequency (or AF) is an option that allows a receiver to re-tune to a different frequency that provides the same station, when the first signal becomes too weak (e.g. when moving out of range). This is often used in car stereo systems, enabled by Radio Data System (RDS), or the U.S.-based Radio Broadcast Data System (RBDS).
Radio technology |
https://en.wikipedia.org/wiki/Ethyl%20acetoacetate | The organic compound ethyl acetoacetate (EAA) is the ethyl ester of acetoacetic acid. It is a colorless liquid. It is widely used as a chemical intermediate in the production of a wide variety of compounds. It is used as a flavoring for food.
Preparation
Ethyl acetoacetate is produced industrially by treatment of diketene with ethanol.
The preparation of ethyl acetoacetate is a classic laboratory procedure. It is prepared via the Claisen condensation of ethyl acetate. Two moles of ethyl acetate condense to form one mole each of ethyl acetoacetate and ethanol.
Reactivity
Acidity
Ethyl acetoacetate is diprotic:
CH3C(O)CH2CO2Et + NaH → CH3C(O)CH(Na)CO2Et + H2
CH3C(O)CH(Na)CO2Et + BuLi → LiCH2C(O)CH(Na)CO2Et + BuH
Keto-enol tautomerism
Ethyl acetoacetate is subject to keto-enol tautomerism. In the neat liquid at 33 °C, the enol consists of 15% of the total.
Multicarbon building block
Ethyl acetoacetic acid is a building block in organic synthesis since the protons alpha to carbonyl groups are acidic, and the resulting carbanion undergoes nucleophilic substitution. Ethyl acetoacetate is often used in the acetoacetic ester synthesis similar to diethyl malonate in the malonic ester synthesis or the Knoevenagel condensation. A subsequent thermal decarboxylation is also possible.
The dianion of ethylacetoacetate is also a useful building block, except that the electrophile adds to the terminal carbon. The strategy can be depicted in the following simplified form:
LiCH2C(O)CH(Na)CO2Et + RX → RCH2C(O)CH(Na)CO2Et + LiX
Ligand
Similar to the behavior of acetylacetone, the enolate of ethyl acetoacetate can also serve as a bidentate ligand. For example, it forms purple coordination complexes with iron(III) salts:
Reduction
Reduction of ethyl acetoacetate gives ethyl 3-hydroxybutyrate.
Transesterification
Ethyl acetoacetate transesterifies to give benzyl acetoacetate via a mechanism involving acetylketene. Ethyl (and other) acetoacetates nitrosate readily with equimolar |
https://en.wikipedia.org/wiki/Systems%20management | Systems management refers to enterprise-wide administration of distributed systems including (and commonly in practice) computer systems. Systems management is strongly influenced by network management initiatives in telecommunications. The application performance management (APM) technologies are now a subset of Systems management. Maximum productivity can be achieved more efficiently through event correlation, system automation and predictive analysis which is now all part of APM.
Centralized management has a time and effort trade-off that is related to the size of the company, the expertise of the IT staff, and the amount of technology being used:
For a small business startup with ten computers, automated centralized processes may take more time to learn how to use and implement than just doing the management work manually on each computer.
A very large business with thousands of similar employee computers may clearly be able to save time and money, by having IT staff learn to do systems management automation.
A small branch office of a large corporation may have access to a central IT staff, with the experience to set up automated management of the systems in the branch office, without need for local staff in the branch office to do the work.
Systems management may involve one or more of the following tasks:
Hardware inventories.
Server availability monitoring and metrics.
Software inventory and installation.
Anti-virus and anti-malware.
User's activities monitoring.
Capacity monitoring.
Security management.
Storage management.
Network capacity and utilization monitoring.
Anti-manipulation management
Functions
Functional groups are provided according to International Telecommunication Union Telecommunication Standardization Sector (ITU-T) Common management information protocol (X.700) standard. This framework is also known as Fault, Configuration, Accounting, Performance, Security (FCAPS).
Fault management
Troubleshooting, error logging an |
https://en.wikipedia.org/wiki/Multivector | In multilinear algebra, a multivector, sometimes called Clifford number or multor, is an element of the exterior algebra of a vector space . This algebra is graded, associative and alternating, and consists of linear combinations of simple -vectors (also known as decomposable -vectors or -blades) of the form
where are in .
A -vector is such a linear combination that is homogeneous of degree (all terms are -blades for the same ). Depending on the authors, a "multivector" may be either a -vector or any element of the exterior algebra (any linear combination of -blades with potentially differing values of ).
In differential geometry, a -vector is a vector in the exterior algebra of the tangent vector space; that is, it is an antisymmetric tensor obtained by taking linear combinations of the exterior product of tangent vectors, for some integer . A differential -form is a -vector in the exterior algebra of the dual of the tangent space, which is also the dual of the exterior algebra of the tangent space.
For and , -vectors are often called respectively scalars, vectors, bivectors and trivectors; they are respectively dual to 0-forms, 1-forms, 2-forms and 3-forms.
Exterior product
The exterior product (also called the wedge product) used to construct multivectors is multilinear (linear in each input), associative and alternating. This means for vectors u, v and w in a vector space V and for scalars α, β, the exterior product has the properties:
Linear in an input:
Associative:
Alternating:
The exterior product of k vectors or a sum of such products (for a single k) is called a grade k multivector, or a k-vector. The maximum grade of a multivector is the dimension of the vector space V.
Linearity in either input together with the alternating property implies linearity in the other input. The multilinearity of the exterior product allows a multivector to be expressed as a linear combination of exterior products of basis vectors of V. The exterior |
https://en.wikipedia.org/wiki/IGB%20Eletr%C3%B4nica | IGB Eletrônica S.A. (Portuguese for IGB Electronics), doing business as Gradiente, is a Brazilian consumer electronics company based in Manaus, and with offices in São Paulo. The company designs and markets many product lines, including video (e.g. televisions, DVD players), audio, home theater, high end acoustics, office and mobile stereo, wireless, mobile/smart phones, and tablets for the Brazilian market.
History
The company was founded in 1964. In 1993 they founded Playtronic, a fully owned subsidiary who licensed the manufacturing of Nintendo consoles in Brazil, and while publishing games for various systems they also provided Portuguese translations of some games (among them, South Park and Shadow Man for the Nintendo 64). However, they stopped the partnership with Nintendo in 2003 because of the high price of the dollar at the time.
In 1997, Gradiente established a joint venture with Finland-based telecommunications manufacturing firm Nokia, where they were granted the license to manufacture variants of Nokia mobile phones locally under the Nokia and Gradiente brand names.
The Gradiente iPhone case
In 2000, Gradiente, now legally known as IGB Eletrônica SA, filed for the brand name "iphone" in Brazil's INPI (National Institute of Industrial Property, the trademark authority). Only by 2008 the Brazilian government granted full brand ownership for Gradiente, and currently (since January 2012), the company is selling Android-based smartphones under this name. Until 2008 that trademark is fully owned by IGB Eletrônica SA, which released its Android-powered iphone neo one under the Gradiente brand. The iphone neo one is sold for R$ 599 (about US$287), a dual-SIM handset running Android 2.3.4 Gingerbread. It has a 3.7-inch, 320 x 480 display, a 700 MHz CPU, 2GB of expandable storage, Bluetooth, 3G, WiFi and 5 / 0.3-megapixel camera.
See also
List of phonograph manufacturers
Gradiente Expert |
https://en.wikipedia.org/wiki/United%20States%20Army%20Medical%20Research%20Institute%20of%20Infectious%20Diseases | The United States Army Medical Research Institute of Infectious Diseases (USAMRIID; ) is the U.S Army's main institution and facility for defensive research into countermeasures against biological warfare. It is located on Fort Detrick, Maryland, near Washington, D.C., and is a subordinate lab of the United States Army Medical Research and Development Command (USAMRDC), headquartered on the same installation.
USAMRIID is the only U.S. Department of Defense (DoD) laboratory equipped to study highly hazardous viruses at Biosafety Level 4 within positive pressure personnel suits.
USAMRIID employs both military and civilian scientists as well as highly specialized support personnel, totaling around 800 people. In the 1950s and 1960s, USAMRIID and its predecessor unit pioneered unique, state-of-the-art biocontainment facilities which it continues to maintain and upgrade. Investigators at its facilities frequently collaborate with the Centers for Disease Control and Prevention, the World Health Organization, and major biomedical and academic centers worldwide.
USAMRIID was the first bio-facility of its type to research the Ames strain of anthrax, determined through genetic analysis to be the bacterium used in the 2001 anthrax attacks.
Mission
USAMRIID's 1983 mission statement mandated that the Institute:
USAMRIID's current mission statement is:
National and international legal status
By U.S. Department of Defense (DoD) directive, as well as additional U.S. Army guidance, USAMRIID performs its "biological agent medical defense" research in support of the needs of the three military services. This mission, and all work done at USAMRIID, must remain within the spirit and letter of both President Richard Nixon's 1969 and 1970 Executive Orders renouncing the use of biological and toxin weapons, and the U.N. Biological Weapons Convention of 1972.
History
Beginnings
USAMRIID traces its institutional lineage to the early 1950s, when Lt. Col. Abram S. Benenson was appoi |
https://en.wikipedia.org/wiki/Resummation | In mathematics and theoretical physics, resummation is a procedure to obtain a finite result from a divergent sum (series) of functions. Resummation involves a definition of another (convergent) function in which the individual terms defining the original function are re-scaled, and an integral transformation of this new function to obtain the original function. Borel resummation is probably the most well-known example.
The simplest method is an extension of a variational approach to higher order based on a paper by R.P. Feynman and H. Kleinert.
In quantum mechanics it was extended to any order here, and in quantum field theory here.
See also Chapters 16–20 in the textbook cited below.
See also
Perturbation theory
Perturbation theory (quantum mechanics) |
https://en.wikipedia.org/wiki/Anomalous%20magnetic%20dipole%20moment | In quantum electrodynamics, the anomalous magnetic moment of a particle is a contribution of effects of quantum mechanics, expressed by Feynman diagrams with loops, to the magnetic moment of that particle. The magnetic moment, also called magnetic dipole moment, is a measure of the strength of a magnetic source.
The "Dirac" magnetic moment, corresponding to tree-level Feynman diagrams (which can be thought of as the classical result), can be calculated from the Dirac equation. It is usually expressed in terms of the g-factor; the Dirac equation predicts . For particles such as the electron, this classical result differs from the observed value by a small fraction of a percent. The difference is the anomalous magnetic moment, denoted and defined as
Electron
The one-loop contribution to the anomalous magnetic moment—corresponding to the first and largest quantum mechanical correction—of the electron is found by calculating the vertex function shown in the adjacent diagram. The calculation is relatively straightforward and the one-loop result is:
where is the fine-structure constant. This result was first found by Julian Schwinger in 1948 and is engraved on his tombstone. As of 2016, the coefficients of the QED formula for the anomalous magnetic moment of the electron are known analytically up to and have been calculated up to order :
The QED prediction agrees with the experimentally measured value to more than 10 significant figures, making the magnetic moment of the electron the most accurately verified prediction in the history of physics. (See Precision tests of QED for details.)
The current experimental value and uncertainty is:
According to this value, is known to an accuracy of around 1 part in 10 billion (1010). This required measuring to an accuracy of around 1 part in 10 trillion (1013).
Muon
The anomalous magnetic moment of the muon is calculated in a similar way to the electron. The prediction for the value of the muon anomalous magnetic mom |
https://en.wikipedia.org/wiki/Brace%20%28tool%29 | A brace is a hand tool used with a bit (drill bit or auger) to drill holes, usually in wood. Pressure is applied to the top while the handle is rotated. If the bit's lead and cutting spurs are both in good working order, the user should not have to apply any pressure other than for balance: the lead will pull the bit through the wood. Bits used to come in a variety of types but the more commonly used Ridgeway and Irwin-pattern bits also rely on a tip called a snail, which is a tapered threaded screw that pulls the bit forward.
The U-shaped handle is a crank. It gives the brace much greater torque than other kinds of hand-powered drills. A brace and bit can be used to drill wider and deeper holes than can a geared hand-powered drill. The cost of the greater torque is lower rotational speed; it is easy for a geared hand drill to achieve a rotational speed of several hundred revolutions per minute, while it would require considerable effort to achieve even 100 rpm with a brace.
The front of the brace consists of a chuck spindle with V-shaped brackets or clamps inside. Turning the spindle of the chuck in a clockwise direction tightens the drill bit in the chuck; turning counterclockwise loosens the bit for removal.
In most modern braces, immediately behind the chuck is a three position gear release that allows ratcheting of the handle when in tight spots. Turning the gear release from the center position allows ratcheting the brace in the required direction. Turning the gear release fully clockwise lets it remove wood in a clockwise direction with the ratchet action going counterclockwise. Placing the gear release fully counterclockwise allows turning the brace and bit in a counterclockwise direction, usually to remove the drill bit from the hole. The center position of the gear release prohibits the ratcheting effect.
The U-shaped crank has a wooden spindle on it and—along with the top spindle—is allowed to freely turn under the hands without stressing the hands |
https://en.wikipedia.org/wiki/CLOVER2000 | CLOVER is the name of a series or class of modem modulation techniques (“waveforms”) specifically designed for use over high frequency (HF) radio systems.
CLOVER-II was the first CLOVER waveform sold commercially, developed by Ray Petit, W7GHM, and HAL Communications in 1990–92.
CLOVER-2000 is a higher-rate and wider bandwidth version of CLOVER developed in 1995.
CLOVER-400 is a special 400 Hz wide waveform that was developed for Globe Wireless.
Modulation schemes
In ARQ mode, all CCB's (CLOVER Control Blocks) use BPSK modulation and data blocks may be sent using BPSK, QPSK, 8PSK (see phase-shift keying), 8P2A, or 16P4A (see QAM) modulation. Data is sent in 255-byte blocks. The FEC broadcast mode of CLOVER-2000 is usually disabled although special formats are available for specific applications.
The coding polynomial protocol could be shared after payment in Bit Coin
Radio Interface requirements for CLOVER-2000
The CLOVER waveform offers high performance, error correction, and spectral efficiency. CLOVER is specifically designed for use over HF radio communications links. It may be used with virtually any modern HF SSB radio. However, certain special set-up and adjustment techniques are required to get maximum performance when using CLOVER.
See also
Shortwave
Radioteletype
PSK31
PACTOR
SITOR |
https://en.wikipedia.org/wiki/PSK63 | PSK63 (meaning Phase Shift Keying at a rate of 63 baud) is a digital radio modulation mode used primarily in the amateur radio field to conduct real-time keyboard-to-keyboard informal text chat between amateur radio operators.
History
In April 2003, Skip Teller, KH6TY, the creator of Digipan, requested an addition to Moe (AE4JY) Wheatley's PSKCore DLL to support the PSK63 mode. Subsequently, another mode - PSK125 - has been added to the PSKCore DLL.
Unlike PSK63F, PSK63 does not use forward error correction (FEC).
PSK 63 is twice as fast as PSK63F's but exactly the same speed as PSK125F.
Mode Support
PSK63 is now supported directly in KH6TY's own QuikPSK software, as well as in Digipan, AA6YQ's WinWarbler, F6CTE's MultiPSK, AE4JY's WinPSK, HB9DRV's DM780, PSK31 Deluxe, MMVARI, Fldigi, MIXW, and DL4RCK's RCKRtty. It is also supported in hardware by the Elecraft KX3.
Others are likely to follow, now that version 1.17 of the PSKCore dll supports both PSK31 and PSK63. QuikPSK, MultiPSK and PSK31 Deluxe can decode up to 24 signals simultaneously. QuickPSK has a unique additional capability to send colour thumbnail pictures (32x32 pixel, 16 colours) using the PSK63 mode.
PSK Software Core
A PSK63-only version of the PSKCore dll is also available at KH6TY's web site for use with any software that uses PSKCore to implement PSK31. Simply by replacing the original PSKCore file (it is suggested that you rename the original rather than deleting it) with the new version, the PSK31 software supports PSK63 instead of PSK31.
This technique has been used during early experiments with the PSK63 mode, but it is not likely to continue to be very widely used now that software that supports PSK63 directly has become widely available.
The official distribution of the PSKCore DLL, which supports PSK31, PSK63, and PSK125, is available on Moe (AE4JY) Wheatley's website.
See also
PSK31
MT63
Varicode
Radioteletype
Shortwave |
https://en.wikipedia.org/wiki/Tensor%20product%20of%20Hilbert%20spaces | In mathematics, and in particular functional analysis, the tensor product of Hilbert spaces is a way to extend the tensor product construction so that the result of taking a tensor product of two Hilbert spaces is another Hilbert space. Roughly speaking, the tensor product is the metric space completion of the ordinary tensor product. This is an example of a topological tensor product. The tensor product allows Hilbert spaces to be collected into a symmetric monoidal category.
Definition
Since Hilbert spaces have inner products, one would like to introduce an inner product, and therefore a topology, on the tensor product that arises naturally from those of the factors. Let and be two Hilbert spaces with inner products and respectively. Construct the tensor product of and as vector spaces as explained in the article on tensor products. We can turn this vector space tensor product into an inner product space by defining
and extending by linearity. That this inner product is the natural one is justified by the identification of scalar-valued bilinear maps on and linear functionals on their vector space tensor product. Finally, take the completion under this inner product. The resulting Hilbert space is the tensor product of and
Explicit construction
The tensor product can also be defined without appealing to the metric space completion. If and are two Hilbert spaces, one associates to every simple tensor product the rank one operator from to that maps a given as
This extends to a linear identification between and the space of finite rank operators from to The finite rank operators are embedded in the Hilbert space of Hilbert–Schmidt operators from to The scalar product in is given by
where is an arbitrary orthonormal basis of
Under the preceding identification, one can define the Hilbertian tensor product of and that is isometrically and linearly isomorphic to
Universal property
The Hilbert tensor product is characterized by the foll |
https://en.wikipedia.org/wiki/PACTOR | PACTOR is a radio modulation mode used by amateur radio operators, marine radio stations, military or government users such as the US Department of Homeland Security, and radio stations in isolated areas to send and receive digital information via radio.
PACTOR is an evolution of both AMTOR and packet radio; its name is a portmanteau of these two technologies' names.
PACTOR uses a combination of simple FSK modulation, and the ARQ protocol for robust error detection and data throughput. Generational improvements to PACTOR include PACTOR II, PACTOR III, and PACTOR IV which are capable of higher speed transmission. PACTOR is most commonly used on frequencies between 1 MHz and 30 MHz.
History
PACTOR (Latin: The mediator) was developed by Special Communications Systems GmbH (SCS) and released to the public in 1991.
PACTOR was developed in order to improve the reception of digital data when the received signal was weak or noisy. It combines the bandwidth efficiency of packet radio with the error-correction (CRC) and automatic repeat request (ARQ) of AMTOR. Amateur radio operators were instrumental in developing and implementing these digital modes.
Current uses
PACTOR radio equipment consists of an HF transceiver, a computer and a terminal node controller. Software running on the computer drives the terminal node controller. The most commonly used amateur program for this purpose is Airmail.
PACTOR is used by Amateur Bulletin board system operators to exchange public messages, and open conversations across the world. It is also used by the NTSD (digital) portion of the ARRL's National Traffic System (NTS) to pass digital ARRL Radiograms. Newer PACTOR modes are used to transfer large binary data files and Internet e-mail, particularly via the Winlink global e-mail system.
The SailMail network transfers e-mail on behalf of marine stations.
Technical characteristics
PACTOR is a set of standardized modes used by radio operators for FSK radioteletype transfer of d |
https://en.wikipedia.org/wiki/Neuromuscular-blocking%20drug | Neuromuscular-blocking drugs, or Neuromuscular blocking agents (NMBAs), block transmission at the neuromuscular junction, causing paralysis of the affected skeletal muscles. This is accomplished via their action on the post-synaptic acetylcholine (Nm) receptors.
In clinical use, neuromuscular block is used adjunctively to anesthesia to produce paralysis, firstly to paralyze the vocal cords, and permit endotracheal intubation, and secondly to optimize the surgical field by inhibiting spontaneous ventilation, and causing relaxation of skeletal muscles. Because the appropriate dose of neuromuscular-blocking drug may paralyze muscles required for breathing (i.e., the diaphragm), mechanical ventilation should be available to maintain adequate respiration.
This class of medications helps to reduce patient movement, breathing, or ventilator dyssynchrony and allows lower insufflation pressures during laparoscopy. It has several indications for use in the intense care unit. It can help reduce hoarseness in voice as well as injury to the vocal cord during intubation. In addition, it plays an important role in facilitating mechanical ventilation in patients with poor lung function.
Patients are still aware of pain even after full conduction block has occurred; hence, general anesthetics and/or analgesics must also be given to prevent anesthesia awareness.
Nomenclature
Neuromuscular blocking drugs are often classified into two broad classes:
Pachycurares, which are bulky molecules with nondepolarizing activity
Leptocurares, which are thin and flexible molecules that tend to have depolarizing activity.
It is also common to classify them based on their chemical structure.
Acetylcholine, suxamethonium, and decamethonium
Suxamethonium was synthesised by connecting two acetylcholine molecules and has the same number of heavy atoms between methonium heads as decamethonium. Just like acetylcholine, succinylcholine, decamethonium and other polymethylene chai |
https://en.wikipedia.org/wiki/Working%20animal | A working animal is an animal, usually domesticated, that is kept by humans and trained to perform tasks instead of being slaughtered to harvest animal products. Some are used for their physical strength (e.g. oxen and draft horses) or for transportation (e.g. riding horses and camels), while others are service animals trained to execute certain specialized tasks (e.g. hunting and guide dogs, messenger pigeons, and fishing cormorants). They may also be used for milking or herding. Some, at the end of their working lives, may also be used for meat or leather.
The history of working animals may predate agriculture as dogs were used by hunter-gatherer ancestors; around the world, millions of animals work in relationship with their owners. Domesticated species are often bred for different uses and conditions, especially horses and working dogs. Working animals are usually raised on farms, though some are still captured from the wild, such as dolphins and some Asian elephants.
People have found uses for a wide variety of abilities in animals, and even industrialised societies use many animals for work. People use the strength of horses, elephants, and oxen to pull carts and move loads. Police forces use dogs for finding illegal substances and assisting in apprehending wanted persons, others use dogs to find game or search for missing or trapped people. People use various animals—camels, donkeys, horses, dogs, etc.—for transport, either for riding or to pull wagons and sleds. Other animals, including dogs and monkeys, help disabled people.
On rare occasions, wild animals are not only tamed, but trained to perform work—though often solely for novelty or entertainment, as such animals tend to lack the trustworthiness and mild temper of true domesticated working animals. Conversely, not all domesticated animals are working animals. For example, while cats may catch mice, it is an instinctive behaviour, not one that can be trained by human intervention. Other domesticated |
https://en.wikipedia.org/wiki/Index%20Fungorum | Index Fungorum is an international project to index all formal names (scientific names) in the fungus kingdom. the project is based at the Royal Botanic Gardens, Kew, one of three partners along with Landcare Research and the Institute of Microbiology, Chinese Academy of Sciences.
It is somewhat comparable to the International Plant Names Index (IPNI), in which the Royal Botanic Gardens is also involved. A difference is that where IPNI does not indicate correct names, the Index Fungorum does indicate the status of a name. In the returns from the search page a currently correct name is indicated in green, while others are in blue (a few, aberrant usages of names are indicated in red). All names are linked to pages giving the correct name, with lists of synonyms.
Index Fungorum is one of three nomenclatural repositories recognized by the Nomenclature Committee for Fungi; the others are MycoBank and Fungal Names.
Current names in Index Fungorum (Species Fungorum)
The main part of Index Fungorum is intended to be a global list of all fungal names which have ever been validly defined, but many of them are conflicting or no longer used. Species Fungorum is a closely related project based at the Royal Botanical Gardens, Kew supported by CABI to decide a consistent subset of the Index Fungorum names which can be recommended as currently valid. It is possible to search in either the Index Fungorum or the Species Fungorum list separately and the Index Fungorum results also give a cross-reference to Species Fungorum where an entry is available - names without such a reference are generally only of historical interest and should not be considered reliable for present use.
Life Science Identifiers (LSIDs)
Index Fungorum provides Life Science Identifiers (LSIDs) for records in its database.
Services
Index Fungorum provides a SOAP protocol web service for searching its database and retrieving records. A WSDL file describing the services is available.
See also
Australian |
https://en.wikipedia.org/wiki/Critical%20depth | In biological oceanography, critical depth is defined as a hypothetical surface mixing depth where phytoplankton growth is precisely matched by losses of phytoplankton biomass within the depth interval. This concept is useful for understanding the initiation of phytoplankton blooms.
History
Critical depth as an aspect of biological oceanography was introduced in 1935 by Gran and Braarud. It became prominent in 1953 when Harald Sverdrup published the "Critical Depth Hypothesis" based on observations he had made in the North Atlantic on the Weather Ship M.
Sverdrup provides a simple formula based on several assumptions that relates the critical depth to plankton growth and loss rates and light levels. Under his hypothesis, net production in the mixed layer exceeds losses only if the mixed layer is shallower than the critical depth. His hypothesis has often been misconstrued to suggest that spring phytoplankton blooms are triggered when the mixed layer depth shoals to become shallower than the critical depth in the spring. In fact, this is not what Sverdrup intended.
Since 1953, further investigation and research has been conducted to better define the critical depth and its role in initiating spring phytoplankton blooms. Recent analysis of satellite data suggest that the theory does not explain all spring blooms, particularly the North Atlantic spring bloom. Several papers have appeared recently that suggest a different relationship between the mixed layer depth and spring bloom timing.
Definition
Sverdrup defines the critical depth at which integrated photosynthesis equals integrated respiration. This can also be described as the depth at which the integral of net growth rate over the water column becomes zero. The net growth rate equals the gross photosynthetic rate minus loss terms. Gross photosynthesis exponentially decays from a maximum near the surface to approach zero with depth. It is affected by the amount and angle of solar radiation and the clarity |
https://en.wikipedia.org/wiki/Transparent%20Network%20Substrate | Transparent Network Substrate (TNS), a proprietary Oracle computer-networking technology, supports homogeneous peer-to-peer connectivity on top of other networking technologies such as TCP/IP, SDP and named pipes. TNS operates mainly for connection to Oracle databases.
Protocol
TNS uses a proprietary protocol. Some details have, however, been reverse engineered.
See also
Transparency (computing)
Oracle Net Services
Protocol stack |
https://en.wikipedia.org/wiki/ABTS | In biochemistry, ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) is a chemical compound used to observe the reaction kinetics of specific enzymes. A common use for it is in the enzyme-linked immunosorbent assay (ELISA) to detect the binding of molecules to each other.
It is commonly used as a substrate with hydrogen peroxide for a peroxidase enzyme (such as horseradish peroxidase) or alone with blue multicopper oxidase enzymes (such as laccase or bilirubin oxidase). Its use allows the reaction kinetics of peroxidases themselves to be followed. In this way it also can be used to indirectly follow the reaction kinetics of any hydrogen peroxide-producing enzyme, or to simply quantify the amount of hydrogen peroxide in a sample.
The formal reduction potentials for ABTS are high enough for it to act as an electron donor for the reduction of oxo species such as molecular oxygen and hydrogen peroxide, particularly at the less-extreme pH values encountered in biological catalysis. Under these conditions, the sulfonate groups are fully deprotonated and the mediator exists as a dianion.
ABTS–· + e– → ABTS2– E° = 0.67 V vs SHE
ABTS + e– → ABTS–· E° = 1.08 V vs SHE
This compound is chosen because the enzyme facilitates the reaction with hydrogen peroxide, turning it into a green and soluble end-product. Its new absorbance maximum of 420 nm light (ε = 3.6 × 104 M–1 cm–1) can easily be followed with a spectrophotometer, a common laboratory instrument.
It is sometimes used as part of a glucose estimating reagent when finding glucose concentrations of solutions such as blood serum.
ABTS is also frequently used by the food industry and agricultural researchers to measure the antioxidant capacities of foods. In this assay, ABTS is converted to its radical cation by addition of sodium persulfate. This radical cation is blue in color and absorbs light at 415, 645, 734 and 815 nm. The ABTS radical cation is reactive towards most antioxidants including phenolics, th |
https://en.wikipedia.org/wiki/Flowing-afterglow%20mass%20spectrometry | Flowing-afterglow mass spectrometry (FA-MS), is an analytical chemistry technique for the sensitive detection of trace gases. Trace gas molecules are ionized by the production and flow of thermalized hydrated hydronium cluster ions in a plasma afterglow of helium or argon carrier gas along a flow tube following the introduction of a humid air sample. These ions react in multiple collisions with water molecules, their isotopic compositions reach equilibrium and the relative magnitudes of their isotopomers are measured by mass spectrometry.
Brief History
Over the years many variations of the instrument have been made. In the beginning during the 1960s there was the study of flowing afterglow plasma. This study was done by Eldon Ferguson, Art Schmeltekopf and Fred Fehsenfeld at National Bureau of Standards in Boulder, Colorado. Then in the 1970s it was flowing drift tube, flowing afterglow Langmuir probe (FALP), and variable temperature flowing afterglow Langmuir probe (VT-FLAP). With the addition of the drift tube the kinetics of a reaction could be studied in the gas phase. With the flowing afterglow Langmuir probe the electron density within the reaction region of the drift tube can be studied. With the VT-FLAP version of flowing afterglow the reactions temperature dependence could be studied. Now in the 2000s the ambient version of flowing afterglow mass spectrometry is flowing atmospheric pressure afterglow mass spectrometry (FAPA-MS).The FAPA allows for simple or no sample preparations but the humidity of the instrument's environment may have an effect on a sample fragmentation pattern. Since the cost of helium is steady rising some have started to use alternative methods with ambient flowing afterglow to conserve resources. Instead of using continuously flowing afterglow helium some use interrupted helium flow to conserve gas and Schlieren imaging to maximize the molecular ions produced and the instrument step-up.
Application(s)
Trace gas analysis
One of th |
https://en.wikipedia.org/wiki/Fenestra | A fenestra (fenestration; : fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biological sciences. It is the Latin word for "window", and is used in various fields to describe a pore in an anatomical structure.
Biological morphology
In morphology, fenestrae are found in cancellous bones, particularly in the skull. In anatomy, the round window and oval window are also known as the fenestra rotunda and the fenestra ovalis. In microanatomy, fenestrae are found in endothelium of fenestrated capillaries, enabling the rapid exchange of molecules between the blood and surrounding tissue. The elastic layer of the tunica intima is a fenestrated membrane. In surgery, a fenestration is a new opening made in a part of the body to enable drainage or access.
Plant biology and mycology
In plant biology, the perforations in a perforate leaf are also described as fenestrae, and the leaf is called a fenestrate leaf. The leaf window is also known as a fenestra, and is a translucent structure that transmits light, as in Fenestraria.
Examples of fenestrate structures in the fungal kingdom include the symmetrically arranged gaps in the indusium ("skirt") of the mushroom Phallus duplicatus, and the thallus of the coral lichen Pulchrocladia retipora.
Zoology
In zoology, the trilobite Fenestraspis possessed extensive fenestrae in the posterior part of the body. In the paleognathae, there is an ilio–ischiatic fenestra.
Fenestrae are also used to distinguish the three types of amniote:
See also
Fenestron, a shrouded tail rotor of a helicopter |
https://en.wikipedia.org/wiki/Bullous%20pemphigoid | Bullous pemphigoid (a type of pemphigoid) is an autoimmune pruritic skin disease that typically occurs in people aged over 60, that may involve the formation of blisters (bullae) in the space between the epidermal and dermal skin layers. It is classified as a type II hypersensitivity reaction, which involves formation of anti-hemidesmosome antibodies, causing a loss of keratinocytes to basement membrane adhesion.
Signs and symptoms
Clinically, the earliest lesions may appear as a hives-like red raised rash, but could also appear dermatitic, targetoid, lichenoid, nodular, or even without a rash (essential pruritus). Tense bullae eventually erupt, most commonly at the inner thighs and upper arms, but the trunk and extremities are frequently both involved. Any part of the skin surface can be involved. Oral lesions are present in a minority of cases. The disease may be acute, but can last from months to years with periods of exacerbation and remission.
Several other skin diseases may have similar symptoms. However, milia are more common with epidermolysis bullosa acquisita, because of the deeper antigenic targets. A more ring-like configuration with a central depression or centrally collapsed bullae may indicate linear IgA disease. Nikolsky's sign is negative, unlike pemphigus vulgaris, where it is positive.
Causes
In most cases of bullous pemphigoid, no clear precipitating factors are identified. Potential precipitating events that have been reported include exposure to ultraviolet light and radiation therapy. Onset of pemphigoid has also been associated with certain drugs, including furosemide, nonsteroidal anti-inflammatory agents, DPP-4 inhibitors, captopril, penicillamine, and antibiotics.
Pathophysiology
The bullae are formed by an immune reaction, initiated by the formation of IgG autoantibodies targeting dystonin, also called bullous pemphigoid antigen 1, and/or type XVII collagen, also called bullous pemphigoid antigen 2, which is a component of hemidesm |
https://en.wikipedia.org/wiki/Unit%20propagation | Unit propagation (UP) or Boolean Constraint propagation (BCP) or the one-literal rule (OLR) is a procedure of automated theorem proving that can simplify a set of (usually propositional) clauses.
Definition
The procedure is based on unit clauses, i.e. clauses that are composed of a single literal, in conjunctive normal form. Because each clause needs to be satisfied, we know that this literal must be true. If a set of clauses contains the unit clause , the other clauses are simplified by the application of the two following rules:
every clause (other than the unit clause itself) containing is removed (the clause is satisfied if is);
in every clause that contains this literal is deleted ( can not contribute to it being satisfied).
The application of these two rules lead to a new set of clauses that is equivalent to the old one.
For example, the following set of clauses can be simplified by unit propagation because it contains the unit clause .
Since contains the literal , this clause can be removed altogether. Since contains the negation of the literal in the unit clause, this literal can be removed from the clause. The unit clause is not removed; this would make the resulting set not equivalent to the original one; this clause can be removed if already stored in some other form (see section "Using a partial model"). The effect of unit propagation can be summarized as follows.
The resulting set of clauses is equivalent to the above one. The new unit clause that results from unit propagation can be used for a further application of unit propagation, which would transform into .
Unit propagation and resolution
The second rule of unit propagation can be seen as a restricted form of resolution, in which one of the two resolvents must always be a unit clause. As for resolution, unit propagation is a correct inference rule, in that it never produces a new clause that was not entailed by the old ones. The differences between unit propagation and re |
https://en.wikipedia.org/wiki/Entomoplasmatales | Entomoplasmatales is a small order of mollicute bacteria.
The genus Spiroplasma is part of this order.
Phylogeny
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI)
See also
List of bacterial orders
List of bacteria genera |
https://en.wikipedia.org/wiki/GeoGebra | GeoGebra (a portmanteau of geometry and algebra) is an interactive geometry, algebra, statistics and calculus application, intended for learning and teaching mathematics and science from primary school to university level. GeoGebra is available on multiple platforms, with apps for desktops (Windows, macOS and Linux), tablets (Android, iPad and Windows) and web. It is presently owned by Indian edutech firm Byju's.
History
GeoGebra's creator, Markus Hohenwarter, started the project in 2001 as part of his master's thesis at the University of Salzburg. After a successful Kickstarter campaign, GeoGebra expanded its offering to include an iPad, an Android and a Windows Store app version. In 2013, GeoGebra incorporated Xcas into its CAS view. The project is now freeware (with open-source portions) and multi-lingual, and Hohenwarter continues to lead its development at the University of Linz.
GeoGebra includes both commercial and not-for-profit entities that work together from the head office in Linz, Austria, to expand the software and cloud services available to users.
In December 2021, GeoGebra was acquired by edtech conglomerate Byju's for approximately $100 million USD.
Features
GeoGebra is an interactive mathematics software suite for learning and teaching science, technology, engineering, and mathematics from primary school up to the university level. Constructions can be made with points, vectors, segments, lines, polygons, conic sections, inequalities, implicit polynomials and functions, all of which can be edited dynamically later. Elements can be entered and modified using mouse and touch controls, or through an input bar. GeoGebra can store variables for numbers, vectors and points, calculate derivatives and integrals of functions, and has a full complement of commands like Root or Extremum. Teachers and students can use GeoGebra as an aid in formulating and proving geometric conjectures.
GeoGebra's main features are:
Interactive geometry environment (2D |
https://en.wikipedia.org/wiki/Boolean-valued%20model | In mathematical logic, a Boolean-valued model is a generalization of the ordinary Tarskian notion of structure from model theory. In a Boolean-valued model, the truth values of propositions are not limited to "true" and "false", but instead take values in some fixed complete Boolean algebra.
Boolean-valued models were introduced by Dana Scott, Robert M. Solovay, and Petr Vopěnka in the 1960s in order to help understand Paul Cohen's method of forcing. They are also related to Heyting algebra semantics in intuitionistic logic.
Definition
Fix a complete Boolean algebra B and a first-order language L; the signature of L will consist of a collection of constant symbols, function symbols, and relation symbols.
A Boolean-valued model for the language L consists of a universe M, which is a set of elements (or names), together with interpretations for the symbols. Specifically, the model must assign to each constant symbol of L an element of M, and to each n-ary function symbol f of L and each n-tuple of elements of M, the model must assign an element of M to the term f(a0,...,an-1).
Interpretation of the atomic formulas of L is more complicated. To each pair a and b of elements of M, the model must assign a truth value to the expression ; this truth value is taken from the Boolean algebra B. Similarly, for each n-ary relation symbol R of L and each n-tuple of elements of M, the model must assign an element of B to be the truth value .
Interpretation of other formulas and sentences
The truth values of the atomic formulas can be used to reconstruct the truth values of more complicated formulas, using the structure of the Boolean algebra. For propositional connectives, this is easy; one simply applies the corresponding Boolean operators to the truth values of the subformulae. For example, if φ(x) and ψ(y,z) are formulas with one and two free variables, respectively, and if a, b, c are elements of the model's universe to be substituted for x, y, and z, then the truth va |
https://en.wikipedia.org/wiki/Orthographical%20variant | In biology, within the science of scientific nomenclature, i.e. the naming of organisms, an orthographical variant (abbreviated orth. var.) in botany or an orthographic error in zoology, is a spelling mistake, typing mistake or writing mistake within a scientific publication that resulted in a somewhat different name being accidentally used for an already-named organism. The rules that govern what to do when this happens are laid out in the relevant codes of nomenclature.
In botanical names
In botanical nomenclature, an orthographical variant (abbreviated orth. var.) is a variant spelling of the same name. For example, Hieronima and Hyeronima are orthographical variants of Hieronyma. One of the spellings must be treated as the correct one. In this case, the spelling Hieronyma has been conserved and is to be used as the correct spelling.
An inadvertent use of one of the other spellings has no consequence: the name is to be treated as if it were correctly spelled. Any subsequent use is to be corrected.
Orthographical variants are treated in Art 61 of the ICBN.
In zoological names
In zoology, "orthographical variants" in the formal sense do not exist; a misspelling or orthographic error is treated as a lapsus, a form of inadvertent error. The first reviser is allowed to choose one variant for mandatory further use, but in other ways, these errors generally have no further formal standing. Inadvertent misspellings are treated in Art. 32-33 of the ICZN. |
https://en.wikipedia.org/wiki/Davis%E2%80%93Putnam%20algorithm | The Davis–Putnam algorithm was developed by Martin Davis and Hilary Putnam for checking the validity of a first-order logic formula using a resolution-based decision procedure for propositional logic. Since the set of valid first-order formulas is recursively enumerable but not recursive, there exists no general algorithm to solve this problem. Therefore, the Davis–Putnam algorithm only terminates on valid formulas. Today, the term "Davis–Putnam algorithm" is often used synonymously with the resolution-based propositional decision procedure (Davis–Putnam procedure) that is actually only one of the steps of the original algorithm.
Overview
The procedure is based on Herbrand's theorem, which implies that an unsatisfiable formula has an unsatisfiable ground instance, and on the fact that a formula is valid if and only if its negation is unsatisfiable. Taken together, these facts imply that to prove the validity of φ it is enough to prove that a ground instance of ¬φ is unsatisfiable. If φ is not valid, then the search for an unsatisfiable ground instance will not terminate.
The procedure for checking validity of a formula φ roughly consists of these three parts:
put the formula ¬φ in prenex form and eliminate quantifiers
generate all propositional ground instances, one by one
check if each instance is satisfiable.
If some instance is unsatisfiable, then return that φ is valid. Else continue checking.
The last part is a SAT solver based on resolution (as seen on the illustration), with an eager use of unit propagation and pure literal elimination (elimination of clauses with variables that occur only positively or only negatively in the formula).
Input: A set of clauses Φ.
Output: A Truth Value: true if Φ can be satisfied, false otherwise.
function DP-SAT(Φ)
repeat
// unit propagation:
while Φ contains a unit clause {l} do
for every clause c in Φ that contains l do
Φ ← remove-from-formula(c, Φ);
|
https://en.wikipedia.org/wiki/Initiative%20for%20Open%20Authentication | Initiative for Open Authentication (OATH) is an industry-wide collaboration to develop an open reference architecture using open standards to promote the adoption of strong authentication. It has close to thirty coordinating and contributing members and is proposing standards for a variety of authentication technologies, with the aim of lowering costs and simplifying their functions.
Terminology
The name OATH is an acronym from the phrase "open authentication", and is pronounced as the English word "oath".
OATH is not related to OAuth, an open standard for authorization.
See also
HOTP: An HMAC-Based One-Time Password Algorithm (RFC 4226)
TOTP: Time-Based One-Time Password Algorithm (RFC 6238)
OCRA: OATH Challenge-Response Algorithm (RFC 6287)
Portable Symmetric Key Container (PSKC) (RFC 6030)
Dynamic Symmetric Key Provisioning Protocol (DSKPP) (RFC 6063)
FIDO Alliance |
https://en.wikipedia.org/wiki/Zimbra | Zimbra Collaboration, formerly known as the Zimbra Collaboration Suite (ZCS) before 2019, is a collaborative software suite that includes an email server and a web client.
Zimbra was initially developed by LiquidSys, which changed their name to Zimbra, Inc. on 26 July 2005. The Zimbra Collaboration Suite was first released in 2005. The company was subsequently purchased by Yahoo! on September 17, 2007, and later sold to VMware on January 12, 2010. In July 2013, it was sold by VMware to Telligent Systems which changed its name to Zimbra, Inc. in September 2013. It was then acquired by Synacor on 18 August 2015.
According to former Zimbra President and CTO Scott Dietzen, the name for Zimbra is derived from the song "I Zimbra" by Talking Heads.
Edition
The software consists of both client and server components, and at one time also offered a desktop email client, called Zimbra Desktop. Two versions of Zimbra are available: an open-source version, and a commercially supported version ("Network Edition") with closed-source components such as a proprietary Messaging Application Programming Interface connector to Outlook for calendar and contact synchronization.
The now discontinued Zimbra Desktop was a full-featured free desktop email client. Development was discontinued under VMware's stewardship in 2013 but was restarted in February 2014, but was ended again by 2019. The web client featured an HTML5 offline mode starting with version 8.5.
The Zimbra Web Client is a full-featured collaboration suite that supports email and group calendars. At one time it featured document-sharing using an Ajax web interface that enabled tool tips, drag-and-drop items, and right-click menus in the UI. Today it has document sharing, chat, and videoconferencing. Also included are advanced searching capabilities and date relations, online document authoring, "Zimlet" mashups, and a full administration UI. It is written using the Zimbra Ajax Toolkit.
The Zimbra Server uses several open |
https://en.wikipedia.org/wiki/Cantor%27s%20paradox | In set theory, Cantor's paradox states that there is no set of all cardinalities. This is derived from the theorem that there is no greatest cardinal number. In informal terms, the paradox is that the collection of all possible "infinite sizes" is not only infinite, but so infinitely large that its own infinite size cannot be any of the infinite sizes in the collection. The difficulty is handled in axiomatic set theory by declaring that this collection is not a set but a proper class; in von Neumann–Bernays–Gödel set theory it follows from this and the axiom of limitation of size that this proper class must be in bijection with the class of all sets. Thus, not only are there infinitely many infinities, but this infinity is larger than any of the infinities it enumerates.
This paradox is named for Georg Cantor, who is often credited with first identifying it in 1899 (or between 1895 and 1897). Like a number of "paradoxes" it is not actually contradictory but merely indicative of a mistaken intuition, in this case about the nature of infinity and the notion of a set. Put another way, it is paradoxical within the confines of naïve set theory and therefore demonstrates that a careless axiomatization of this theory is inconsistent.
Statements and proofs
In order to state the paradox it is necessary to understand that the cardinal numbers are totally ordered, so that one can speak about one being greater or less than another. Then Cantor's paradox is:
This fact is a direct consequence of Cantor's theorem on the cardinality of the power set of a set.
Another consequence of Cantor's theorem is that the cardinal numbers constitute a proper class. That is, they cannot all be collected together as elements of a single set. Here is a somewhat more general result.
Discussion and consequences
Since the cardinal numbers are well-ordered by indexing with the ordinal numbers (see Cardinal number, formal definition), this also establishes that there is no greatest ordinal number |
https://en.wikipedia.org/wiki/S%C3%B8rensen%20formol%20titration | The Sørensen formol titration(SFT) invented by S. P. L. Sørensen in 1907 is a titration of an amino acid with potassium hydroxide in the presence of formaldehyde. It is used in the determination of protein content in samples.
If instead of an amino acid an ammonium salt is used the reaction product with formaldehyde is hexamethylenetetramine:
The liberated hydrochloric acid is then titrated with the base and the amount of ammonium salt used can be determined.
With an amino acid the formaldehyde reacts with the amino group to form a methylene amino (R-N=CH2) group. The remaining acidic carboxylic acid group can then again be titrated with base.
In winemaking
Formol titration is one of the methods used in winemaking to measure yeast assimilable nitrogen needed by wine yeast in order to successfully complete fermentation.
Accuracy in formol titration
There has been some inaccuracies of the SFT caused by the differences in the basicity of the nitrogen in different amino acids which were explained by S. L. Jodidi. For instances, proline(an amino acid), histidine, and lysine yields too low values compared to the theory. Unlike alpha, monobasic (containing one amino group per molecule) amino acids, these amino (or imino) acids' nitrogens have inconstant basicity, which results in partial reaction with formaldehyde.
In case of tyrosine, the actual results are too high due to the negative hydroxyl group (-OH), which acts as a base. This explanation is supported by the fact that phenylalanine can be accurately titrated. |
https://en.wikipedia.org/wiki/Prelog%20strain | In organic chemistry, transannular strain (also called Prelog strain after chemist Vladimir Prelog) is the unfavorable interactions of ring substituents on non-adjacent carbons. These interactions, called transannular interactions, arise from a lack of space in the interior of the ring, which forces substituents into conflict with one another. In medium-sized cycloalkanes, which have between 8 and 11 carbons constituting the ring, transannular strain can be a major source of the overall strain, especially in some conformations, to which there is also contribution from large-angle strain and Pitzer strain. In larger rings, transannular strain drops off until the ring is sufficiently large that it can adopt conformations devoid of any negative interactions.
Transannular strain can also be demonstrated in other cyclo-organic molecules, such as lactones, lactams, ethers, cycloalkenes, and cycloalkynes. These compounds are not without significance, since they are particularly useful in the study of transannular strain. Furthermore, transannular interactions are not relegated to only conflicts between hydrogen atoms, but can also arise from larger, more complicated substituents interacting across a ring.
Thermodynamics
By definition, strain implies discomfiture, so it should follow that molecules with large amounts of transannular strain should have higher energies than those without. Cyclohexane, for the most part, is without strain and is therefore quite stable and low in energy. Rings smaller than cyclohexane, like cyclopropane and cyclobutane, have significant tension caused by small-angle strain, but there is no transannular strain. While there is no small-angle strain present in medium-sized rings, there does exist something called large-angle strain. Some angle and torsional strain is used by rings with more than nine members to relieve some of the distress caused by transannular strain.
As the plot to the left indicates, the relative energies of cycloalkanes i |
https://en.wikipedia.org/wiki/CGMS-A | Copy Generation Management System – Analog (CGMS-A) is a copy protection mechanism for analog television signals. It consists of a waveform inserted into the non-picture vertical blanking interval (VBI) of an analogue video signal. If a compatible recording device (for example, a DVD recorder) detects this waveform, it may block or restrict recording of the video content.
It is not the same as the broadcast flag, which is designed for use in digital television signals, although the concept is the same. There is a digital form of CGMS specified as CGMS-D which is required by the DTCP ("5C") protection standard.
History
CGMS-A has been in existence since 1995, and has been standardized by various organizations including the IEC and EIA/CEA. It is used in devices such as PVRs/DVRs, DVD players and recorders, D-VHS, and Blu-ray recorders, as well certain television broadcasts. More recent TiVo firmware releases comply with CGMS-A signals.
Applications
Implementation of CGMS-A is required for certain applications by DVD CCA license. D-VHS and some DVD recorders comply with CGMS-A signal on analog inputs. The technology requires minimal signal processing.
Where the source signal is analogue (e.g. VHS, analogue broadcast), the CGMS-A signalling may be present in that source.
Where the source signal is digital (e.g. DVD, digital broadcast), then the Copy Control Information (CCI) is carried in metadata in the digital transport or program stream, and a compliant hardware device (e.g. a DVD player) will read that data, and encode it into the analogue video signal generated within the device itself.
There is no blanket legal requirement for devices which record video to detect or act upon the CGMS-A information. For example, the DMCA "does not require manufacturers of consumer electronics, telecommunications or computing equipment to design their products affirmatively to respond to any particular technological measure.".
Standardization
CGMS-A is standardized throug |
https://en.wikipedia.org/wiki/Polytomy | An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tree that contains any multifurcations can be described as a multifurcating tree.
Soft polytomies vs. hard polytomies
Two types of polytomies are recognised, soft and hard polytomies.
Soft polytomies are the result of insufficient phylogenetic information: though the lineages diverged at different times – meaning that some of these lineages are closer relatives than others, and the available data does not allow recognition of this. Most polytomies are soft, meaning that they would be resolved into a typical tree of dichotomies if better data were available.
In contrast, a hard polytomy represents a true divergence event of three or more lineages.
Applications
Interpretations for a polytomy depend on the individuals, that are represented in the phylogenetic tree.
Species polytomies
If the lineages in the phylogenetic tree stand for species, a polytomy shows the simultaneous speciation of three or more species. In particular situations they may be common, for example when a species that has rapidly expanded its range or is highly panmictic undergoes peripatric speciation in different regions.
An example is the Drosophila simulans species complex. Here, the ancestor seems to have colonized two islands at the same time but independently, yielding two equally old but divergently evolved daughter species
Molecular polytomies
If a phylogenetic tree is reconstructed from DNA sequence data of a particular gene, a hard polytomy arises when three or more sampled genes trace their ancestry to a single gene in an ancestral organism. In contrast, a soft polytomy stems from branches on gene trees of finite temporal duration but for which no substitutions have occurred.
Recognizing hard polytomies
As DNA sequence evolution is usua |
https://en.wikipedia.org/wiki/Boole%27s%20expansion%20theorem | Boole's expansion theorem, often referred to as the Shannon expansion or decomposition, is the identity: , where is any Boolean function, is a variable, is the complement of , and and are with the argument set equal to and to respectively.
The terms and are sometimes called the positive and negative Shannon cofactors, respectively, of with respect to . These are functions, computed by restrict operator, and (see valuation (logic) and partial application).
It has been called the "fundamental theorem of Boolean algebra". Besides its theoretical importance, it paved the way for binary decision diagrams (BDDs), satisfiability solvers, and many other techniques relevant to computer engineering and formal verification of digital circuits.
In such engineering contexts (especially in BDDs), the expansion is interpreted as a if-then-else, with the variable being the condition and the cofactors being the branches ( when is true and respectively when is false).
Statement of the theorem
A more explicit way of stating the theorem is:
Variations and implications
XOR-Form The statement also holds when the disjunction "+" is replaced by the XOR operator:
Dual form There is a dual form of the Shannon expansion (which does not have a related XOR form):
Repeated application for each argument leads to the Sum of Products (SoP) canonical form of the Boolean function . For example for that would be
Likewise, application of the dual form leads to the Product of Sums (PoS) canonical form (using the distributivity law of over ):
Properties of cofactors
Linear properties of cofactors:
For a Boolean function F which is made up of two Boolean functions G and H the following are true:
If then
If then
If then
If then
Characteristics of unate functions:
If F is a unate function and...
If F is positive unate then
If F is negative unate then
Operations with cofactors
Boolean difference:
The Boolean difference or Boolean derivative of the f |
https://en.wikipedia.org/wiki/Translational%20medicine | Translational medicine (often called translational science, of which it is a form) develops the clinical practice applications of the basic science aspects of the biomedical sciences; that is, it translates basic science to applied science in medical practice. It is defined by the European Society for Translational Medicine as "an interdisciplinary branch of the biomedical field supported by three main pillars: benchside, bedside, and community". The goal of translational medicine is to combine disciplines, resources, expertise, and techniques within these pillars to promote enhancements in prevention, diagnosis, and therapies. Accordingly, translational medicine is a highly interdisciplinary field, the primary goal of which is to coalesce assets of various natures within the individual pillars in order to improve the global healthcare system significantly.
History
Translational medicine is a rapidly growing discipline in biomedical research and aims to expedite the discovery of new diagnostic tools and treatments by using a multi-disciplinary, highly collaborative, "bench-to-bedside" approach. Within public health, translational medicine is focused on ensuring that proven strategies for disease treatment and prevention are actually implemented within the community. One prevalent description of translational medicine, first introduced by the Institute of Medicine's Clinical Research Roundtable, highlights two roadblocks (i.e., distinct areas in need of improvement): the first translational block (T1) prevents basic research findings from being tested in a clinical setting; the second translational block (T2) prevents proven interventions from becoming standard practice.
The National Institutes of Health has made a major push to fund translational medicine, especially within biomedical research, with a focus on cross-functional collaborations (e.g., between researchers and clinicians); leveraging new technology and data analysis tools; and increasing the speed a |
https://en.wikipedia.org/wiki/Hyphen-minus | The hyphen-minus is the most commonly used type of hyphen, widely used in digital documents. In ASCII or on most keyboards it is the only character that resembles a minus sign or a dash so it is also used for these. The name "hyphen-minus" derives from the original ASCII standard, where it was called "hyphen–(minus)". The character is referred to as a "hyphen", a "minus sign", or a "dash" according to the context where it is being used.
Description
In early monospaced font typewriters and character encodings, a single key/code was almost always used for hyphen, minus, various dashes, and strikethrough, since they all have a roughly similar appearance. The current Unicode Standard specifies distinct characters for a number of different dashes, an unambiguous minus sign ("Unicode minus") at code point U+2212, and various types of hyphen including the unambiguous "Unicode hyphen" at U+2010 and the hyphen-minus at U+002D. When a hyphen is called for, the hyphen-minus is a common choice as it is well known, easy to enter on keyboards, and still the only form recognised by many data formats and computer languages. Though the Unicode Standard states that the U+2010 hyphen is "preferred" over the hyphen-minus, the standard itself uses the hyphen-minus as its hyphen character.
In most modern fonts, the hyphen-minus is either identical or very similar to the "Unicode hyphen".
In mathematical texts that include the plus sign, use of the hyphen-minus as a minus sign typically results in an unattractive appearance. Unlike the Unicode minus sign, the hyphen-minus is generally smaller and at a different height than the horizontal line in the plus sign; see the image.
Many word processors will word wrap at a hyphen-minus, but not after the "Unicode hyphen" sign.
Uses
Typing
This character is typed when a hyphen or a minus sign is wanted. Based on old typewriter conventions, it is common to use a pair to represent an em dash , and to put spaces around it to represent a s |
https://en.wikipedia.org/wiki/Operational%20amplifier%20applications | This article illustrates some typical operational amplifier applications. A non-ideal operational amplifier's equivalent circuit has a finite input impedance, a non-zero output impedance, and a finite gain. A real op-amp has a number of non-ideal features as shown in the diagram, but here a simplified schematic notation is used, many details such as device selection and power supply connections are not shown. Operational amplifiers are optimised for use with negative feedback, and this article discusses only negative-feedback applications. When positive feedback is required, a comparator is usually more appropriate. See Comparator applications for further information.
Practical considerations
Operational amplifiers parameter requirements
In order for a particular device to be used in an application, it must satisfy certain requirements. The operational amplifier must
have large open-loop signal gain (voltage gain of 200,000 is obtained in early integrated circuit exemplars), and
have input impedance large with respect to values present in the feedback network.
With these requirements satisfied, the op-amp is considered ideal, and one can use the method of virtual ground to quickly and intuitively grasp the 'behavior' of any of the op-amp circuits below.
Component specification
Resistors used in practical solid-state op-amp circuits are typically in the kΩ range. Resistors much greater than 1 MΩ cause excessive thermal noise and make the circuit operation susceptible to significant errors due to bias or leakage currents.
Input bias currents and input offset
Practical operational amplifiers draw a small current from each of their inputs due to bias requirements (in the case of bipolar junction transistor-based inputs) or leakage (in the case of MOSFET-based inputs).
These currents flow through the resistances connected to the inputs and produce small voltage drops across those resistances. Appropriate design of the feedback network can alleviate problems ass |
https://en.wikipedia.org/wiki/Optical%20molasses | Optical molasses is a laser cooling technique that can cool neutral atoms to temperatures lower than a magneto-optical trap (MOT). An optical molasses consists of 3 pairs of counter-propagating circularly polarized laser beams intersecting in the region where the atoms are present. The main difference between optical molasses and a MOT is the absence of magnetic field in the former. Therefore, unlike a MOT, an optical molasses provides only cooling and no trapping. While a typical Sodium MOT can cool atoms down to 300μK, optical molasses can cool the atoms down to 40μK, an order of magnitude colder.
History
When laser cooling was proposed in 1975, a theoretical limit on the lowest possible temperature was predicted. Known as the Doppler limit, , this was given by the lowest possible temperature attainable considering the cooling of two-level atoms by Doppler cooling and the heating of atoms due to momentum diffusion from the scattering of laser photons. Here, , is the natural line-width of the atomic transition, , is the reduced Planck constant and, , is the Boltzmann constant.
Experiments at the National Institute of Standards and Technology, Gaithersburg, found the temperature of cooled atoms to be well below the theoretical limit. Initially, it was a surprise to theorists, until the full explanation came out.
In 1985, Chu et al. directed a thermal beam of sodium atoms through an optical molasses region formed by counter-propagating light from a frequency-doubled Neodymium:YAlG laser. They measured the average temperature by quickly shutting off the beams and measuring the fluorescence of the released atoms. They measured an average temperature of , near the Doppler cooling limit of sodium.
Theory
The best explanation of the phenomenon of optical molasses is based on the principle of polarization gradient cooling. Counterpropagating beams of circularly polarized light cause a standing wave, where the light polarization is linear but the direction rotates alo |
https://en.wikipedia.org/wiki/Litter%20%28zoology%29 | A litter is the live birth of multiple offspring at one time in animals from the same mother and usually from one set of parents, particularly from three to eight offspring. The word is most often used for the offspring of mammals, but can be used for any animal that gives birth to multiple young. In comparison, a group of eggs and the offspring that hatch from them are frequently called a clutch, while young birds are often called a brood. Animals from the same litter are referred to as litter-mates.
Litter
A species' average litter size is generally equal to one half of the number of teats and the maximum litter size generally matches the number of teats. Not all species abide by this rule, however. The naked mole rat, for example, averages roughly eleven young per birth and has eleven teats.
Animals frequently display grouping behavior in herds, swarms, flocks, or colonies, and these multiple births derive similar advantages. A litter offers some protection from predation, not particularly to the individual young but to the parents' investment in breeding. With multiple young, predators could eat several and others could still survive to reach maturity, but with only one offspring, its loss could mean a wasted breeding season. The other significant advantage is the chance for the healthiest young animals to be favored from a group. Rather than it being a conscious decision on the part of the parents, the fittest and strongest baby competes most successfully for food and space, leaving the weakest young, or runts, to die through lack of care.
In the wild, only a small percentage, if any, of the litter may survive to maturity, whereas for domesticated animals and those in captivity with human care the whole litter almost always survives. Kittens and puppies are in this group. Carnivorans, rodents, and pigs usually have litters, while primates and larger herbivores usually have singletons. |
https://en.wikipedia.org/wiki/Emergency%20power%20system | An emergency power system is an independent source of electrical power that supports important electrical systems on loss of normal power supply. A standby power system may include a standby generator, batteries and other apparatus. Emergency power systems are installed to protect life and property from the consequences of loss of primary electric power supply. It is a type of continual power system.
They find uses in a wide variety of settings from homes to hospitals, scientific laboratories, data centers, telecommunication equipment and ships. Emergency power systems can rely on generators, deep-cycle batteries, flywheel energy storage or fuel cells.
History
Emergency power systems were used as early as World War II on naval ships. In combat, a ship may lose the function of its boilers, which power the steam turbines for the ship's generator. In such a case, one or more diesel engines are used to drive back-up generators. Early transfer switches relied on manual operation; two switches would be placed horizontally, in line and the "on" position facing each other. a rod is placed in between. In order to operate the switch one source must be turned off, the rod moved to the other side and the other source turned on.
Operation in buildings
Mains power can be lost due to downed lines, malfunctions at a sub-station, inclement weather, planned blackouts or in extreme cases a grid-wide failure. In modern buildings, most emergency power systems have been and are still based on generators. Usually, these generators are Diesel engine driven, although smaller buildings may use a gasoline engine driven generator.
Some larger building have gas turbines, but they can take 5 or up to 30 minutes to produce power.
Lately, more use is being made of deep cycle batteries and other technologies such as flywheel energy storage or fuel cells. These latter systems do not produce polluting gases, thereby allowing the placement to be done within the building. Also, as a second advan |
https://en.wikipedia.org/wiki/Domestic%20goose | A domestic goose is a goose that humans have domesticated and kept for their meat, eggs, or down feathers. Domestic geese have been derived through selective breeding from the wild greylag goose (Anser anser domesticus) and swan goose (Anser cygnoides domesticus).
Origins
In Europe, northern Africa, and western Asia, the original domesticated geese are derived from the greylag goose (Anser anser). In eastern Asia, the original domesticated geese are derived from the swan goose (Anser cygnoides); these are commonly known as Chinese geese. Both have been widely introduced in more recent times, and modern flocks in both areas (and elsewhere, such as Australia and North America) may consist of either species or hybrids between them. Chinese geese may be readily distinguished from European geese by the large knob at the base of the bill, though hybrids may exhibit every degree of variation between the two species.
Charles Darwin remarked in The Variation of Animals and Plants Under Domestication that the domestication of geese is of a very ancient date. There is archaeological evidence for domesticated geese in Egypt more than 4,000 years ago. It has been proposed that geese were domesticated around 3000 BCE in southeastern Europe, possibly in Greece, but reliable evidence of domestic geese comes from a much later period (8th century BCE) in The Odyssey. Another potential domestication site is in Egypt during the Old Kingdom (2686–1991 BCE) due to iconographic evidence of goose exploitation, but this scenario for the original domestication event has been considered less likely. Geese were also herded by ancient Mesopotamians for food and sacrifices and depicted in Mesopotamian art from the early Dynastic Period (2900–2350 BCE) onwards. Certainly, fully domesticated geese were present during the New Kingdom times in Egypt (1552–1151 BCE) and contemporaneously in Europe, and goose husbandry involving several varieties was well established by the Romans by the 1st century |
https://en.wikipedia.org/wiki/Port-Royal%20Logic | Port-Royal Logic, or Logique de Port-Royal, is the common name of La logique, ou l'art de penser, an important textbook on logic first published anonymously in 1662 by Antoine Arnauld and Pierre Nicole, two prominent members of the Jansenist movement, centered on Port-Royal. Blaise Pascal likely contributed considerable portions of the text. Its linguistic companion piece is the Port-Royal Grammar (1660) by Arnauld and Lancelot.
Written in French, it became quite popular and was in use up to the twentieth century, introducing the reader to logic, and exhibiting strong Cartesian elements in its metaphysics and epistemology (Arnauld having been one of the main philosophers whose objections were published, with replies, in Descartes' Meditations on First Philosophy). The Port-Royal Logic is sometimes cited as a paradigmatic example of traditional term logic.
The philosopher Louis Marin particularly studied it in the 20th century (La Critique du discours, Éditions de Minuit, 1975), while Michel Foucault considered it, in The Order of Things, one of the bases of the classical épistémè.
Among the contributions of the Port-Royal Logic is the popularization of the distinction between comprehension and extension, which would later become a more refined distinction between intension and extension. Roughly speaking: a definition with more qualifications or features (the intension) denotes a class with fewer members (the extension), and vice versa.
The main idea traces back through the scholastic philosophers to Aristotle's ideas about genus and species, and is fundamental in the philosophy of Leibniz. More recently, it has been related to mathematical lattice theory in formal concept analysis, and independently formalized similarly by Yu. Schreider's group in Moscow, Jon Barwise & Jerry Seligman in Information Flow, and others. |
https://en.wikipedia.org/wiki/Word%20Munchers | Word Munchers is a 1985 video game and the first of the Munchers educational series. It was made by MECC for Apple II, then ported to DOS and Macintosh in 1991. It was re-released in 1996 for Windows and Macintosh as "Word Munchers Deluxe". The concept of the game was designed by Philip R. Bouchard, who also designed The Oregon Trail.
Gameplay
The player controls the Muncher who must move around a grid eating words that match condition at the top of the screen, while avoiding the threatening Troggles. As the player progresses through the levels, the difficulty of the matching conditions increases, and multiple Troggles pursue the Muncher.
Educational goals
The game was designed for first- to fifth-grade students, emphasizing vowel sounds, while teaching students grammar, phonics and reading skills in addition to introducing new words.
Reception |
https://en.wikipedia.org/wiki/Dancing%20Links | In computer science, dancing links (DLX) is a technique for adding and deleting a node from a circular doubly linked list. It is particularly useful for efficiently implementing backtracking algorithms, such as Knuth's Algorithm X for the exact cover problem. Algorithm X is a recursive, nondeterministic, depth-first, backtracking algorithm that finds all solutions to the exact cover problem. Some of the better-known exact cover problems include tiling, the n queens problem, and Sudoku.
The name dancing links, which was suggested by Donald Knuth, stems from the way the algorithm works, as iterations of the algorithm cause the links to "dance" with partner links so as to resemble an "exquisitely choreographed dance." Knuth credits Hiroshi Hitotsumatsu and Kōhei Noshita with having invented the idea in 1979, but it is his paper which has popularized it.
Implementation
As the remainder of this article discusses the details of an implementation technique for Algorithm X, the reader is strongly encouraged to read the Algorithm X article first.
Main ideas
The idea of DLX is based on the observation that in a circular doubly linked list of nodes,
x.left.right ← x.right;
x.right.left ← x.left;
will remove node x from the list, while
x.left.right ← x;
x.right.left ← x;
will restore x'''s position in the list, assuming that x.right and x.left have been left unmodified. This works regardless of the number of elements in the list, even if that number is 1.
Knuth observed that a naive implementation of his Algorithm X would spend an inordinate amount of time searching for 1's. When selecting a column, the entire matrix had to be searched for 1's. When selecting a row, an entire column had to be searched for 1's. After selecting a row, that row and a number of columns had to be searched for 1's. To improve this search time from complexity O(n) to O(1), Knuth implemented a sparse matrix where only 1's are stored.
At all times, each node in the matrix will point to the |
https://en.wikipedia.org/wiki/Worm-like%20chain | The worm-like chain (WLC) model in polymer physics is used to describe the behavior of polymers that are semi-flexible: fairly stiff with successive segments pointing in roughly the same direction, and with persistence length within a few orders of magnitude of the polymer length. The WLC model is the continuous version of the Kratky–Porod model.
Model elements
The WLC model envisions a continuously flexible isotropic rod. This is in contrast to the freely-jointed chain model, which is only flexible between discrete freely hinged segments. The model is particularly suited for describing stiffer polymers, with successive segments displaying a sort of cooperativity: nearby segments are roughly aligned. At room temperature, the polymer adopts a smoothly curved conformation; at K, the polymer adopts a rigid rod conformation.
For a polymer of maximum length , parametrize the path of the polymer as . Allow to be the unit tangent vector to the chain at point , and to be the position vector along the chain, as shown to the right. Then:
and the end-to-end distance .
The energy associated with the bending of the polymer can be written as:
where is the polymer's characteristic persistence length, is the Boltzmann constant, and is the absolute temperature. At finite temperatures, the end-to end distance of the polymer will be significantly shorter than the maximum length . This is caused by thermal fluctuations, which result in a coiled, random configuration of the undisturbed polymer.
The polymer's orientation correlation function can then be solved for, and it follows an exponential decay with decay constant 1/P:
A useful value is the mean square end-to-end distance of the polymer:
Note that in the limit of , then . This can be used to show that a Kuhn segment is equal to twice the persistence length of a worm-like chain. In the limit of , then , and the polymer displays rigid rod behavior. The figure to the right shows the crossover from flexible to stiff b |
https://en.wikipedia.org/wiki/Tulipwood | Most commonly, tulipwood is the greenish yellowish wood yielded from the tulip tree, found on the Eastern side of North America and a similar species in some parts of China. In the United States, it is commonly known as tulip poplar or yellow poplar, even though the tree is not related to the poplars. It is notable for its height, which can exceed 190 feet. The wood is very light, around 490 kg per cubic meter, but very strong and is used in many applications, including furniture, joinery and moldings. It can also be stained very easily and is often used as a low-cost alternative to walnut and cherry in furniture and doors.
Other types
Brazilian
Brazilian tulipwood is a different species. A classic high-quality wood, it is very dense with a lovely figure. It is used for inlays in furniture and for small turned items. Available only in small sizes, it is rarely used in the solid for luxury furniture. Like other woods with a pronounced figure it is rather strongly subject to fashion.
In the nineteenth century Brazilian tulipwood was thought to be the product of the brazilian rosewood Physocalymma scaberrimum (West Indian tulipwood), but in the twentieth century it became clear it was yielded by a species of Dalbergia. At some point it was misidentified as Dalbergia frutescens, a misidentification which can still be found in books aimed at the woodworker. For some decades it has been known to be yielded by Dalbergia decipularis, a species restricted to a small area in Western-Brazil. But both Dalbergia fructescens and Dalbergia decipularis are named (Brazilian tulipwood). Also Dalbergia cearensis kingwood or violetwood, is named tulipwood and Dalbergia oliveri the burmese rosewood is sometimes called "burma tulipwood".
American Tulipwood
The cheap, soft and pale wood from the tuliptree Liriodendron tulipifera is known as American tulipwood or poplar and American whitewood, canary whitewood and canary wood, it is widely used.
Australian
There also exists the "a |
https://en.wikipedia.org/wiki/Myristoylation | Myristoylation is a lipidation modification where a myristoyl group, derived from myristic acid, is covalently attached by an amide bond to the alpha-amino group of an N-terminal glycine residue. Myristic acid is a 14-carbon saturated fatty acid (14:0) with the systematic name of n-tetradecanoic acid. This modification can be added either co-translationally or post-translationally. N-myristoyltransferase (NMT) catalyzes the myristic acid addition reaction in the cytoplasm of cells. This lipidation event is the most common type of fatty acylation and is present in many organisms, including animals, plants, fungi, protozoans and viruses. Myristoylation allows for weak protein–protein and protein–lipid interactions and plays an essential role in membrane targeting, protein–protein interactions and functions widely in a variety of signal transduction pathways.
Discovery
In 1982, Koiti Titani's lab identified an "N-terminal blocking group" on the catalytic subunit of cyclic AMP-dependent protein kinase in cows as n-tetradecanoyl. Almost simultaneously in Claude B. Klee's lab, this same N-terminal blocking group was further characterized as myristic acid. Both labs made this discovery utilizing similar techniques: mass spectrometry and gas chromatography.
N-myristoyltransferase
The enzyme N-myristoyltransferase (NMT) or glycylpeptide N-tetradecanoyltransferase is responsible for the irreversible addition of a myristoyl group to N-terminal or internal glycine residues of proteins. This modification can occur co-translationally or post-translationally. In vertebrates, this modification is carried about by two NMTs, NMT1 and NMT2, both of which are members of the GCN5 acetyltransferase superfamily.
Structure
The crystal structure of NMT reveals two identical subunits, each with its own myristoyl CoA binding site. Each subunit consists of a large saddle-shaped β-sheet surrounded by α-helices. The symmetry of the fold is pseudo twofold. Myristoyl CoA binds at the N |
https://en.wikipedia.org/wiki/Nomenclature%20codes | Nomenclature codes or codes of nomenclature are the various rulebooks that govern biological taxonomic nomenclature, each in their own broad field of organisms. To an end-user who only deals with names of species, with some awareness that species are assignable to genera, families, and other taxa of higher ranks, it may not be noticeable that there is more than one code, but beyond this basic level these are rather different in the way they work.
The introduction of two-part names (binominal nomenclature) for species by Linnaeus was a welcome simplification because as our knowledge of biodiversity expanded, so did the length of the names, many of which had become unwieldy. With all naturalists worldwide adopting binominal nomenclature, there arose several schools of thought about the details. It became ever more apparent that a detailed body of rules was necessary to govern scientific names. From the mid-19th century onwards, there were several initiatives to arrive at worldwide-accepted sets of rules. Presently nomenclature codes govern the naming of:
Algae, Fungi and Plants – International Code of Nomenclature for algae, fungi, and plants (ICN), which in July 2011 replaced the International Code of Botanical Nomenclature (ICBN) and the earlier International Rules of Botanical Nomenclature.
Animals – International Code of Zoological Nomenclature (ICZN)
Bacteria and Archaea – International Code of Nomenclature of Prokaryotes (ICNP), which in 2008 replaced the International Code of Nomenclature of Bacteria (ICNB)
Bacteria and Archaea described from sequence data – Code of Nomenclature of Prokaryotes Described from Sequence Data (SeqCode)
Cultivated plants – International Code of Nomenclature for Cultivated Plants (ICNCP)
Plant associations – International Code of Phytosociological Nomenclature (ICPN)
Viruses – The International Code of Virus Classification and Nomenclature (ICVCN); see also virus classification
Differences between codes
Starting point
The s |
https://en.wikipedia.org/wiki/Random%20number%20generation | Random number generation is a process by which, often by means of a random number generator (RNG), a sequence of numbers or symbols that cannot be reasonably predicted better than by random chance is generated. This means that the particular outcome sequence will contain some patterns detectable in hindsight but impossible to foresee. True random number generators can be hardware random-number generators (HRNGs), wherein each generation is a function of the current value of a physical environment's attribute that is constantly changing in a manner that is practically impossible to model. This would be in contrast to so-called "random number generations" done by pseudorandom number generators (PRNGs), which generate numbers that only look random but are in fact pre-determined—these generations can be reproduced simply by knowing the state of the PRNG.
Various applications of randomness have led to the development of different methods for generating random data. Some of these have existed since ancient times, including well-known examples like the rolling of dice, coin flipping, the shuffling of playing cards, the use of yarrow stalks (for divination) in the I Ching, as well as countless other techniques. Because of the mechanical nature of these techniques, generating large quantities of sufficiently random numbers (important in statistics) required much work and time. Thus, results would sometimes be collected and distributed as random number tables.
Several computational methods for pseudorandom number generation exist. All fall short of the goal of true randomness, although they may meet, with varying success, some of the statistical tests for randomness intended to measure how unpredictable their results are (that is, to what degree their patterns are discernible). This generally makes them unusable for applications such as cryptography. However, carefully designed cryptographically secure pseudorandom number generators (CSPRNGS) also exist, with special featur |
https://en.wikipedia.org/wiki/Bangstad%20syndrome | Bangstad syndrome is a severe, inherited congenital disorder associated with abnormalities of the cell membrane.
It was characterized in 1989 by H. J. Bangstad.
Presentation
Presenting at birth, features of the disorder include moderately severe IUGR, microcephaly, craniosynostosis, moderately severe post-uterine growth retardation, deafness, deep-set eyes, cryptorchidism, truncal obesity and acanthosis nigricans, small teeth, prognathism, dislocated radial heads without generalized skeletal dysplasia, however, tall vertebrae, moderate mental retardation, hypothyroidism, insulin resistance, hypoparathyroidism.
Diagnosis
Treatment |
https://en.wikipedia.org/wiki/John%20Clive%20Ward | John Clive Ward, (1 August 1924 – 6 May 2000) was a Anglo-Australian physicist who made significant contributions to quantum field theory, condensed-matter physics, and statistical mechanics. Andrei Sakharov called Ward one of the titans of quantum electrodynamics.
Ward introduced the Ward–Takahashi identity. He was one of the authors of the Standard Model of gauge particle interactions: his contributions were published in a series of papers he co-authored with Abdus Salam. He is also credited with being an early advocate of the use of Feynman diagrams. It has been said that physicists have made use of his principles and developments "often without knowing it, and generally without quoting him." The Ising model was another one of his research interests.
In 1955, Ward was recruited to work at the Atomic Weapons Research Establishment at Aldermaston. There, he independently derived a version of the Teller–Ulam design, for which he has been called the "father of the British H-bomb".
Early life
John Clive Ward was born in East Ham, London, on 1 August 1924. He was the son of Joseph William Ward, a civil servant who worked in Inland Revenue, and his wife Winifred Palmer, a schoolteacher. He had a sister, Mary Patricia. He attended Chalkwell Elementary School and Westcliff High School for Boys. In 1938 he sat for and won a £100 scholarship to Bishop Stortford College. He took the Higher School Certificate Examination in 1942, receiving distinctions in Mathematics, Physics, Chemistry and Latin, and was offered a postmastership (scholarship) to Merton College, Oxford.
Although the Second World War was raging at the time, Ward was not called up by the Army, and was allowed to complete his Bachelor of Arts degree in Engineering Science with first class honours, studying mathematics under J. H. C. Whitehead and E. C. Titchmarsh. He received a bursary from the Harmsworth Trust, and in October 1946, with the war over, secured a position as a graduate assistant to Maurice |
https://en.wikipedia.org/wiki/JavaStation | The JavaStation was a Network Computer (NC) developed by Sun Microsystems between 1996 and 2000, intended to run only Java applications.
The hardware is based on the design of the Sun SPARCstation series, a very successful line of UNIX workstations.
The JavaStation, as an NC, lacks a hard drive, floppy or CD-ROM drive. It also differs from other Sun systems in having PS/2 keyboard and mouse interfaces and a VGA monitor connector.
Models
There were several models of the JavaStation produced, some being pre-production variants produced in very small numbers.
Production models comprised:
JavaStation-1 (part number JJ-xx), codenamed Mr. Coffee: based on a 110 MHz MicroSPARC IIe CPU, this was housed in a cuboidal Sun "unidisk" enclosure.
JavaStation-NC or JavaStation-10 (part number JK-xx) codenamed Krups: a redesigned Mr. Coffee with a 100 MHz MicroSPARC IIep CPU and enhanced video resolution and color capabilities. Krups was housed in a striking curved vertically oriented enclosure.
Models produced only as prototypes or in limited numbers included:
JavaStation/Fox: a prototype of the Mr Coffee: essentially a repackaged SPARCstation 4 Model 110.
JavaStation-E (part number JE-xx) codenamed Espresso: a Krups with PCI slots and a non-functional ATA interface in a restyled enclosure.
Dover: a JavaStation based on PC compatible hardware, with a Cyrix MediaGXm CPU.
JavaEngine-1: an ATX form-factor version of Krups for embedded systems.
A 68030-based system designed by Diba, Inc. (later acquired by Sun) circa 1996, which could be considered a very early JavaStation-like system.
In addition, Sun envisioned a third-generation "Super JavaStation" after Krups, with a JavaChip co-processor for native Java bytecode execution. This doesn't appear to have been produced.
The JavaStation concept was superseded by the Sun Ray series of thin client terminals.
Operating systems
The JavaStation comes with JavaOS in the flash memory, but it is also possible to install Linux |
https://en.wikipedia.org/wiki/Q15X25 | Q15X25 is a communications protocol for sending data over a radio link. It was designed by amateur radio operator Pawel Jalocha, SP9VRC, to be an open communications standard. Like all amateur radio communications modes, this protocol uses open transmissions which can be received and decoded by anyone with similar equipment. Q15X25 is a form of packet radio. It can be used to interconnect local VHF AX.25 packet networks over transcontinental distances. Anyone can design or adapt the open-source software to develop their own Q15X25 system.
Q15X25 is a digital signal processor-intensive mode designed to pass AX.25 packets on HF with speed and reliability much greater than traditional HF ARQ modems. It uses 15 QPSK modulated carriers separated by 125 Hertz, each modulated at 83.333 baud. Q15X25 uses forward error correction (FEC), and like MT63, uses time- and frequency-interleaving in order to avoid most error sources. The raw transmission data rate is typically 2500 bit/s.
Typically the DSP based receiver and transmitter modulator or codec is implemented as PC software that uses a sound card to connect directly to an SSB transceiver. Linux implementations are usually called "newpsk" or "newqpsk". MixW, a multipurpose communications control and digital modes package on Windows can implement Kiss and/or "TCP/IP over X.25" on either traditional 300 baud, 1200 baud and 2400 baud FSK packet "modems" implemented as DSP via sound card or over Q15X25. The "FlexNet" Windows packet software also has a newqpsk / Q15X25 option.
As with any amateur radio transmission, anyone can listen/decode Q15X25 transmissions, but an amateur radio operation license is required for transmission.
Frequencies (all USB) in use are (MixW center about 1350 Hz higher):
See also
Radioteletype
Shortwave
External links
ARRL description of Q15X25
MixW
Quantized radio modulation modes
Packet radio |
https://en.wikipedia.org/wiki/Warewulf | Warewulf is a computer cluster implementation toolkit that facilitates the process of installing a cluster and long term administration. It does this by changing the administration paradigm to make all of the slave node file systems manageable from one point, and automate the distribution of the node file system during node boot. It allows a central administration model for all slave nodes and includes the tools needed to build configuration files, monitor, and control the nodes. It is totally customizable and can be adapted to just about any type of cluster. From the software administration perspective it does not make much difference if you are running 2 nodes or 500 nodes. The procedure is still the same, which is why Warewulf is scalable from the admins perspective. Also, because it uses a standard chroot'able file system for every node, it is extremely configurable and lends itself to custom environments very easily.
While Warewulf was designed to be a high-performance computing (HPC) system, it is not an HPC system in itself. Warewulf is more along the lines of a distributed Linux distribution, or more specifically a system for replicating and managing small, lightweight Linux systems from one master. Using Warewulf, HPC packages such as LAM/MPI/MPICH, Sun Grid Engine, PVM, etc. can be easily deployed throughout the cluster.
Warewulf solves the problem of slave node management rather than being a strict HPC specific system (even though it was designed with HPC in mind). Because of this it is as flexible as a home grown cluster, but administratively scales very well. As a result of this flexibility and ease of customization, Warewulf has been used not only on production HPC implementations, but also development systems like KASY0 (the first system to break the one hundred dollar per GFLOPS barrier), and non HPC systems such as web server cluster farms, intrusion detection clusters, and high-availability clusters.
See also
oneSIS – another diskless cluster p |
https://en.wikipedia.org/wiki/Coherence%20bandwidth | Coherence bandwidth is a statistical measurement of the range of frequencies over which the channel can be considered "flat", or in other words the approximate maximum bandwidth or frequency interval over which two frequencies of a signal are likely to experience comparable or correlated amplitude fading. If the multipath time delay spread equals D seconds, then the coherence bandwidth in rad/s is given approximately by the equation:
Also coherence bandwidth in Hz is given approximately by the equation:
It can be reasonably assumed that the channel is flat if the coherence bandwidth is greater than the data signal bandwidth.
The coherence bandwidth varies over cellular or PCS communications paths because the multipath spread D varies from path to path.
Application
Frequencies within a coherence bandwidth of one another tend to all fade in a similar or correlated fashion. One reason for designing the CDMA IS-95 waveform with a bandwidth of approximately 1.25 MHz is because in many urban signaling environments the coherence bandwidth Bc is significantly less than 1.25 MHz. Therefore, when fading occurs it occurs only over a relatively small fraction of the total CDMA signal bandwidth. The portion of the signal bandwidth over which fading does not occur typically contains enough signal power to sustain reliable communications. This is the bandwidth over which the channel transfer function remains virtually constant.
Example
If the delay spread D over a particular cellular communication path in an urban environment is 1.9 µs, then using equation above, the coherence bandwidth is approximately 0.53 MHz, which results in frequency selective fading over the IS-95 bandwidth.
See also
Coherence time
Coherence length
Wave mechanics
Radio frequency propagation |
https://en.wikipedia.org/wiki/Eggs%20per%20gram | Eggs per gram (eggs/g) is a laboratory test that determines the number of eggs per gram of feces in patients suspected of having a parasitological infection, such as schistosomiasis.
Measuring the number of eggs per gram is the primary diagnostic method for schistosomiasis, as opposed to a blood test. Eggs per gram or another analyse like larvae per gram of faeces is one of the most important experiments that is done in parasitology labs.
Methods to count the number of eggs per gram:
Willis method
McMaster method
Clayton-Lane method
See also
Kato technique
Helminths |
https://en.wikipedia.org/wiki/Autoepistemic%20logic | The autoepistemic logic is a formal logic for the representation and reasoning of knowledge about knowledge. While propositional logic can only express facts, autoepistemic logic can express knowledge and lack of knowledge about facts.
The stable model semantics, which is used to give a semantics to logic programming with negation as failure, can be seen as a simplified form of autoepistemic logic.
Syntax
The syntax of autoepistemic logic extends that of propositional logic by a modal operator indicating knowledge: if is a formula, indicates that is known. As a result, indicates that is known and indicates that is not known.
This syntax is used for allowing reasoning based on knowledge of facts. For example, means that is assumed false if it is not known to be true. This is a form of negation as failure.
Semantics
The semantics of autoepistemic logic is based on the expansions of a theory, which have a role similar to models in propositional logic. While a propositional model specifies which atomic propositions are true or false, an expansion specifies which formulae are true and which ones are false. In particular, the expansions of an autoepistemic formula make this determination for every subformula contained in . This determination allows to be treated as a propositional formula, as all its subformulae containing are either true or false. In particular, checking whether entails in this condition can be done using the rules of the propositional calculus. In order for a specification to be an expansion, it must be that a subformula is entailed if and only if has been assigned the value true.
In terms of possible world semantics, an expansion of consists of an S5 model of in which the possible worlds consist only of worlds where is true. [The possible worlds need not contain all such consistent worlds; this corresponds to the fact that modal propositions are assigned truth values before checking derivability of the ordinary propositions |
https://en.wikipedia.org/wiki/Fern%20bar | Fern bar is an American slang term for an upscale or preppy (or yuppie) bar or tavern catering to singles, usually decorated with ferns or other greenery, as well as such decor as fake Tiffany lamps. The phrase came into common regional usage in the late 1970s.
History
One of the first fern bars was the original T.G.I. Friday's on the corner of 63rd Street and First Avenue in a neighborhood on the Upper East Side of New York City, where many young single adults lived at the time. The founder, Alan Stillman, borrowed several thousand dollars from his mother, leased a saloon and remodeled it, converting the ambience to one that he thought might be attractive to young single women. The bar opened on March 15, 1965 and was soon copied by other restaurants in the neighborhood.
Another early fern bar, also thought to be the original birthplace of the Lemon Drop martini, was Henry Africa's in San Francisco, California. The bar opened in 1969 at Broadway and Polk Streets by out-of-work veteran Norman Hobday, who by his own account "took the opium-den atmosphere out of the saloons" in favor of "antique lamps and Grandma's living-room furniture." By some accounts Hobday copied the concept from another restaurant, Perry's, which opened several months earlier and was made famous as a singles "meet market" by Armistead Maupin's novel, Tales of the City.
Hobday closed the establishment in 1986, and opened up Eddie Rickenbackers, another eclectic bar, the next year.
Description
Typical drinks served included wine spritzers, lemon drop martinis, frozen daiquirís, Harvey Wallbangers, and piña coladas. Franchises sometimes labeled "fern bars" include T.G.I. Friday's, Bennigan's, and Houlihan's.
Fern bars were gathering places for well-dressed "upscale" young men and women, initially during the sexual revolution of the 1970s and later the yuppie era of the 1980s. Fern bars were frequently talked of disparagingly as singles bars where individuals would go to hit on men or wom |
https://en.wikipedia.org/wiki/Tandemly%20arrayed%20genes | Tandemly arrayed genes (TAGs) are a gene cluster created by tandem duplications, a process in which one gene is duplicated and the copy is found adjacent to the original. They serve to encode large numbers of genes at a time.
TAGs represent a large proportion of genes in a genome, including between 14% and 17% of the human, mouse, and rat genomes. TAG clusters may have as few as two genes, with small clusters predominating, but may consist of hundreds of genes. An example are tandem clusters of rRNA encoding genes. These genes are transcribed faster than they would be if only a single copy of the gene was available. Additionally, a single RNA gene may not be able to provide enough RNA, but tandem repeats of the gene allow sufficient RNA to be produced. For example, cells in a human embryo contain between five and ten million ribosomes, and cell number doubles within 24 hours. In order to provide the necessary ribosomes, multiple RNA polymerases must consecutively transcribe multiple rRNA genes.
In some species, such as Arabidopsis thaliana and Oryza sativa, most TAGs are the result of unequal chromosomal crossover during genetic recombination.
See also
Satellite DNA
Tandem repeats
Notes |
https://en.wikipedia.org/wiki/Primitive%20permutation%20group | In mathematics, a permutation group G acting on a non-empty finite set X is called primitive if G acts transitively on X and the only partitions the G-action preserves are the trivial partitions into either a single set or into |X| singleton sets. Otherwise, if G is transitive and G does preserve a nontrivial partition, G is called imprimitive.
While primitive permutation groups are transitive, not all transitive permutation groups are primitive. The simplest example is the Klein four-group acting on the vertices of a square, which preserves the partition into diagonals. On the other hand, if a permutation group preserves only trivial partitions, it is transitive, except in the case of the trivial group acting on a 2-element set. This is because for a non-transitive action, either the orbits of G form a nontrivial partition preserved by G, or the group action is trivial, in which case all nontrivial partitions of X (which exists for |X| ≥ 3) are preserved by G.
This terminology was introduced by Évariste Galois in his last letter, in which he used the French term équation primitive for an equation whose Galois group is primitive.
Properties
In the same letter in which he introduced the term "primitive", Galois stated the following theorem:If G is a primitive solvable group acting on a finite set X, then the order of X is a power of a prime number p. Further, X may be identified with an affine space over the finite field with p elements, and G acts on X as a subgroup of the affine group.If the set X on which G acts is finite, its cardinality is called the degree of G.
A corollary of this result of Galois is that, if is an odd prime number, then the order of a solvable transitive group of degree is a divisor of In fact, every transitive group of prime degree is primitive (since the number of elements of a partition fixed by must be a divisor of ), and is the cardinality of the affine group of an affine space with elements.
It follows that, if is a prime |
https://en.wikipedia.org/wiki/Prix%20Guzman | The Prix Pierre Guzman (Pierre Guzman Prize) was the name given to two prizes, one astronomical and one medical. Both were established by the will of Anne Emilie Clara Goguet (died June 30, 1891), wife of Marc Guzman, and named after her son Pierre Guzman.
Astronomical
This prize was a sum of 100,000 francs, to be given to a person who succeeded in communicating with a celestial body, other than Mars, and receiving a response. Until this occurred, the will also allowed for the accumulated interest on the 100,000 francs to be given, every five years, to a person who had made significant progress in astronomy. The prize was to be awarded by the French Académie des sciences. Pierre Guzman had been interested in the work of Camille Flammarion, the author of La planète Mars et ses conditions d'habitabilité (The Planet Mars and Its Conditions of Habitability, 1892). Communication with Mars was specifically exempted as many people believed that Mars was inhabited at the time and communication with that planet would not be a difficult enough challenge. The prize was later announced in 1900 by the French Académie des sciences.
The five-yearly prize of interest was awarded, starting in 1905, as follows:
In Dec. 1905, to Henri Joseph Anastase Perrotin. A portion of the prize was also given to Louis Fabry.
In Dec. 1910, to Maurice Loewy.
Nikola Tesla claimed in 1937 that he should receive the prize for "his discovery relating to the interstellar transmission of energy." The prize was awarded to the crew of Apollo 11 in 1969.
Medical
This prize was a sum of 50,000 francs, to be awarded by the French Académie de médecine, to be given to a person who succeeded in developing an effective treatment for the most common forms of heart disease. Until this occurred, the will also allowed for the accumulated interest to be given yearly to someone who had made progress in heart disease.
The yearly prize of interest was awarded as follows:
In 1903, to Paul Bergougnan.
In |
https://en.wikipedia.org/wiki/Peukert%27s%20law | Peukert's law, presented by the German scientist in 1897, expresses approximately the change in capacity of rechargeable lead–acid batteries at different rates of discharge. As the rate of discharge increases, the battery's available capacity decreases, approximately according to Peukert's law.
Batteries
Manufacturers specify the capacity of a battery at a specified discharge rate. For example, a battery might be rated at 100 A·h when discharged at a rate that will fully discharge the battery in 20 hours (at 5 amperes for this example). If discharged at a faster rate the delivered capacity is less. Peukert's law describes a power relationship between the discharge current (normalized to some base rated current) and delivered capacity (normalized to the rated capacity) over some specified range of discharge currents. If Peukert's constant , the exponent, were equal to unity, the delivered capacity would be independent of the current. For a real battery the exponent is greater than unity, and capacity decreases as discharge rate increases. For a lead–acid battery is typically between 1.1 and 1.3. For different lead-acid rechargeable battery technologies it generally ranges from 1.05 to 1.15 for VRSLAB AGM batteries, from 1.1 to 1.25 for gel, and from 1.2 to 1.6 for flooded batteries. The Peukert constant varies with the age of the battery, generally increasing (getting worse) with age. Application at low discharge rates must take into account the battery self-discharge current. At very high currents, practical batteries will give less capacity than predicted with a fixed exponent. The equation does not take into account the effect of temperature on battery capacity.
Formula
For a one-ampere discharge rate, Peukert's law is often stated as
where:
is the capacity at a one-ampere discharge rate, which must be expressed in ampere hours,
is the actual discharge current (i.e. current drawn from a load) in amperes,
is the actual time to discharge the battery, which m |
https://en.wikipedia.org/wiki/Cosmesis | Cosmesis is the preservation, restoration, or bestowing of bodily beauty. In the medical context, it usually refers to the surgical correction of a disfiguring defect, or the cosmetic improvements made by a surgeon following incisions. Its use is generally limited to the additional, usually minor, steps that the surgeon (who is generally operating for noncosmetic indications) takes to improve the aesthetic appearance of the scars associated with the operation. Typical actions include removal of damaged tissue, mitigation of tension on the wound, and/or using fine (thin) sutures to close the outer layer of skin.
Cosmetic surgery is the portion of plastic surgery that concerns itself with the elective improvement of cosmesis.
Prosthetic limbs
The practice of cosmesis, the creation of lifelike limbs made from silicone or PVC, has grown in popularity. Such prosthetics, such as artificial hands, can now be made to mimic the appearance of real limbs, complete with freckles, veins, hair, fingerprints, and even tattoos. Custom-made silicone cosmeses are generally more expensive, costing thousands of US dollars depending on the level of detail. Standard cosmeses come ready-made in various sizes, though they are often not as realistic as their custom-made counterparts. Another option is the custom-made silicone cover, which can be made to match a person's skin tone, but not details such as freckles or wrinkles. Cosmeses are attached to the body using an adhesive, suction, form-fitting, stretchable skin, or a skin sleeve. Cosmeses act as a barrier from dirt, water and other particles, thus protecting the technology inside the glove. |
https://en.wikipedia.org/wiki/Osculating%20plane | In mathematics, particularly in differential geometry, an osculating plane is a plane in a Euclidean space or affine space which meets a submanifold at a point in such a way as to have a second order of contact at the point. The word osculate is from the Latin osculatus which is a past participle of osculari, meaning to kiss. An osculating plane is thus a plane which "kisses" a submanifold.
The osculating plane in the geometry of Euclidean space curves can be described in terms of the Frenet-Serret formulas as the linear span of the tangent and normal vectors.
See also
Normal plane (geometry)
Osculating circle |
https://en.wikipedia.org/wiki/Mott%20insulator | Mott insulators are a class of materials that are expected to conduct electricity according to conventional band theories, but turn out to be insulators (particularly at low temperatures). These insulators fail to be correctly described by band theories of solids due to their strong electron–electron interactions, which are not considered in conventional band theory. A Mott transition is a transition from a metal to an insulator, driven by the strong interactions between electrons. One of the simplest models that can capture Mott transition is the Hubbard model.
The band gap in a Mott insulator exists between bands of like character, such as 3d electron bands, whereas the band gap in charge-transfer insulators exists between anion and cation states.
History
Although the band theory of solids had been very successful in describing various electrical properties of materials, in 1937 Jan Hendrik de Boer and Evert Johannes Willem Verwey pointed out that a variety of transition metal oxides predicted to be conductors by band theory are insulators. With an odd number of electrons per unit cell, the valence band is only partially filled, so the Fermi level lies within the band. From the band theory, this implies that such a material has to be a metal. This conclusion fails for several cases, e.g. CoO, one of the strongest insulators known.
Nevill Mott and Rudolf Peierls also in 1937 predicted the failing of band theory can be explained by including interactions between electrons.
In 1949, in particular, Mott proposed a model for NiO as an insulator, where conduction is based on the formula
(Ni2+O2−)2 → Ni3+O2− + Ni1+O2−.
In this situation, the formation of an energy gap preventing conduction can be understood as the competition between the Coulomb potential U between 3d electrons and the transfer integral t of 3d electrons between neighboring atoms (the transfer integral is a part of the tight binding approximation). The total energy gap is then
Egap = U − 2zt,
whe |
https://en.wikipedia.org/wiki/Hom%20functor | In mathematics, specifically in category theory, hom-sets (i.e. sets of morphisms between objects) give rise to important functors to the category of sets. These functors are called hom-functors and have numerous applications in category theory and other branches of mathematics.
Formal definition
Let C be a locally small category (i.e. a category for which hom-classes are actually sets and not proper classes).
For all objects A and B in C we define two functors to the category of sets as follows:
{| class=wikitable
|-
! Hom(A, –) : C → Set
! Hom(–, B) : C → Set
|-
| This is a covariant functor given by:
Hom(A, –) maps each object X in C to the set of morphisms, Hom(A, X)
Hom(A, –) maps each morphism f : X → Y to the function
Hom(A, f) : Hom(A, X) → Hom(A, Y) given by
for each g in Hom(A, X).
| This is a contravariant functor given by:
Hom(–, B) maps each object X in C to the set of morphisms, Hom(X, B)
Hom(–, B) maps each morphism h : X → Y to the function
Hom(h, B) : Hom(Y, B) → Hom(X, B) given by
for each g in Hom(Y, B).
|}
The functor Hom(–, B) is also called the functor of points of the object B.
Note that fixing the first argument of Hom naturally gives rise to a covariant functor and fixing the second argument naturally gives a contravariant functor. This is an artifact of the way in which one must compose the morphisms.
The pair of functors Hom(A, –) and Hom(–, B) are related in a natural manner. For any pair of morphisms f : B → B′ and h : A′ → A the following diagram commutes:
Both paths send g : A → B to f∘g∘h : A′ → B′.
The commutativity of the above diagram implies that Hom(–, –) is a bifunctor from C × C to Set which is contravariant in the first argument and covariant in the second. Equivalently, we may say that Hom(–, –) is a bifunctor
Hom(–, –) : Cop × C → Set
where Cop is the opposite category to C. The notation HomC(–, –) is sometimes used for Hom(–, –) in order to emphasize the category forming the domain.
Yoneda's lemma
Referr |
https://en.wikipedia.org/wiki/Phosphorescent%20organic%20light-emitting%20diode | Phosphorescent organic light-emitting diodes (PHOLED) are a type of organic light-emitting diode (OLED) that use the principle of phosphorescence to obtain higher internal efficiencies than fluorescent OLEDs. This technology is currently under development by many industrial and academic research groups.
Method of operation
Like all types of OLED, phosphorescent OLEDs emit light due to the electroluminescence of an organic semiconductor layer in an electric current. Electrons and holes are injected into the organic layer at the electrodes and form excitons, a bound state of the electron and hole.
Electrons and holes are both fermions with half integer spin. An exciton is formed by the coulombic attraction between the electron and the hole, and it may either be in a singlet state or a triplet state, depending on the spin states of these two bound species. Statistically, there is a 25% probability of forming a singlet state and 75% probability of forming a triplet state. Decay of the excitons results in the production of light through spontaneous emission.
In OLEDs using fluorescent organic molecules only, the decay of triplet excitons is quantum mechanically forbidden by selection rules, meaning that the lifetime of triplet excitons is long and phosphorescence is not readily observed. Hence it would be expected that in fluorescent OLEDs only the formation of singlet excitons results in the emission of useful radiation, placing a theoretical limit on the internal quantum efficiency (the percentage of excitons formed that result in emission of a photon) of 25%.
However, phosphorescent OLEDs generate light from both triplet and singlet excitons, allowing the internal quantum efficiency of such devices to reach nearly 100%.
This is commonly achieved by doping a host molecule with an organometallic complex. These contain a heavy metal atom at the centre of the molecule, for example platinum or iridium, of which the green emitting complex Ir(mppy)3 is just one of ma |
https://en.wikipedia.org/wiki/Promotional%20video | In video production, a promotional video is marketing or advertising:
Arts, media and entertainment
Promotional recording, an audio or video recording distributed to publicize a recording
Trailer (promotion), a commercial advertisement for a feature film
Music video, a short film that integrates a song with imagery
Corporate use
Corporate video, non-advertisement media created for and commissioned by an organization
Personal use
Video resume, a recording used to promote a jobseeker
Promotional dating video, a video dating recording made to find a romantic partner |
https://en.wikipedia.org/wiki/John%20Pinkerton%20%28computer%20designer%29 | John Maurice McClean Pinkerton (2 August 1919 – 22 December 1997) was a pioneering British computer designer. Along with David Caminer, he designed England's first business computer, the LEO computer, produced by J. Lyons and Co in 1951.
Personal life
John Pinkerton was educated at King Edward's School, Bath, and Clifton College, Bristol. He studied at Trinity College, Cambridge from 1937 to 1940, reading Natural Sciences, and graduating with first class honours. He joined the Air Ministry Research Establishment in Swanage, to work on radar, and went with it to Malvern where it was renamed the Telecommunications Research Establishment (where he met Maurice Wilkes). He returned to Cambridge as a research student at the Cavendish Laboratory.
In 1948 he married Helen McCorkindale. They had a son and a daughter.
Colleagues describe him as having "a disarming way of listening intently to what others said", a "quiet, dry sense of humour", a "fine, critical, but constructive intelligence", "an enviable ability to handle detail", and "friendliness and kindness". They also mention his knowledge of music and English literature and his lively appreciation of good food.
J. Lyons
The catering firm of J. Lyons was known in the high street for its tea and cakes; in the business world it was known for its innovative approach to supply chain management. As early as 1947 the firm decided that the future lay with computers, and since nothing suitable was available, they resolved to build one. They approached Wilkes in Cambridge, who suggested that they construct a copy of the EDSAC machine, and introduced them to Pinkerton whom they recruited as chief engineer.
Pinkerton's approach was to leave the design unchanged as far as possible, while improving reliability by identifying the points of failure (notably electronic valves) and developing test procedures that enabled component failures to be anticipated and prevented.
The machine went into operation in early 1951, and was us |
https://en.wikipedia.org/wiki/George%20E.%20P.%20Box | George Edward Pelham Box (18 October 1919 – 28 March 2013) was a British statistician, who worked in the areas of quality control, time-series analysis, design of experiments, and Bayesian inference. He has been called "one of the great statistical minds of the 20th century".
Education and early life
He was born in Gravesend, Kent, England. Upon entering university he began to study chemistry, but was called up for service before finishing. During World War II, he performed experiments for the British Army exposing small animals to poison gas. To analyze the results of his experiments, he taught himself statistics from available texts. After the war, he enrolled at University College London and obtained a bachelor's degree in mathematics and statistics. He received a PhD from the University of London in 1953, under the supervision of Egon Pearson.
Career and research
From 1948 to 1956, Box worked as a statistician for Imperial Chemical Industries (ICI). While at ICI, he took a leave of absence for a year and served as a visiting professor at North Carolina State University at Raleigh. He later went to Princeton University where he served as Director of the Statistical Research Group.
In 1960, Box moved to the University of Wisconsin–Madison to create the Department of Statistics. In 1980, he was named Vilas Research Professor of Statistics, which is the highest honor given to a member of the University of Wisconsin-Madison faculty. Box and Bill Hunter co-founded the Center for Quality and Productivity Improvement at the University of Wisconsin–Madison in 1985. Box officially retired in 1992, becoming an emeritus professor.
Box published books including Statistics for Experimenters (2nd ed., 2005), Time Series Analysis: Forecasting and Control (4th ed., 2008, with Gwilym Jenkins and Gregory C. Reinsel) and Bayesian Inference in Statistical Analysis. (1973, with George Tiao).
Awards and honours
Box served as president of the American Statistical Association in |
https://en.wikipedia.org/wiki/Karyolysis | Karyolysis (from Greek κάρυον karyon—kernel, seed, or nucleus), and λύσις lysis from λύειν lyein, "to separate") is the complete dissolution of the chromatin of a dying cell due to the enzymatic degradation by endonucleases. The whole cell will eventually stain uniformly with eosin after karyolysis. It is usually associated with karyorrhexis and occurs mainly as a result of necrosis, while in apoptosis after karyorrhexis the nucleus usually dissolves into apoptotic bodies.
Disintegration of the cytoplasm, pyknosis of the nuclei, and karyolysis of the nuclei of scattered transitional cells may be seen in urine from healthy individuals as well as in urine containing malignant cells. Cells with an attached tag of partially preserved cytoplasm were initially described by Papanicolaou and are sometimes called comet or decoy cells. They may have some of the characteristics of malignancy, and it is therefore important that they be recognized for what they are.
Additional images
See also
Apoptosis
Necrosis
Pyknosis
Karyorrhexis |
https://en.wikipedia.org/wiki/Level%20%28optical%20instrument%29 | A level is an optical instrument used to establish or verify points in the same horizontal plane in a process known as levelling. It is used in conjunction with a levelling staff to establish the relative height or levels (the vertical separation) of objects or marks. It is widely used in surveying and construction to measure height differences and to transfer, measure, and set heights of known objects or marks.
It is also known as a surveyor's level, builder's level, dumpy level or the historic "Y" level. It operates on the principle of establishing a visual level relationship between two or more points, for which an inbuilt optical telescope and a highly accurate bubble level are used to achieve the necessary accuracy. Traditionally the instrument was completely adjusted manually to ensure a level line of sight, but modern automatic versions self-compensate for slight errors in the coarse levelling of the instrument, and are thereby quicker to use.
The optical level should not be confused with a theodolite, which can also measure angles in the vertical plane.
Description
The complete unit is normally mounted on a tripod, and the telescope can freely rotate 360° in a horizontal plane. The surveyor adjusts the instrument's level by coarse adjustment of the tripod legs and fine adjustment using three precision levelling screws on the instrument to make the rotational plane horizontal. The surveyor does this with the use of a bull's eye level built into the instrument mount.
The surveyor looks through the eyepiece of the telescope while an assistant holds a vertical level staff which is graduated in inches or centimeters. The level staff is placed with its foot on the point for which the level measurement is required. The telescope is rotated and focused until the level staff is plainly visible in the crosshairs. In the case of a tilting level, the fine level adjustment is made by an altitude screw, using a high accuracy bubble level fixed to the telescope. This |
https://en.wikipedia.org/wiki/HMAC-based%20one-time%20password | HMAC-based one-time password (HOTP) is a one-time password (OTP) algorithm based on HMAC. It is a cornerstone of the Initiative for Open Authentication (OATH).
HOTP was published as an informational IETF RFC 4226 in December 2005, documenting the algorithm along with a Java implementation. Since then, the algorithm has been adopted by many companies worldwide (see below). The HOTP algorithm is a freely available open standard.
Algorithm
The HOTP algorithm provides a method of authentication by symmetric generation of human-readable passwords, or values, each used for only one authentication attempt. The one-time property leads directly from the single use of each counter value.
Parties intending to use HOTP must establish some ; typically these are specified by the authenticator, and either accepted or not by the authenticated:
A cryptographic hash method H (default is SHA-1)
A secret key K, which is an arbitrary byte string and must remain private
A counter C, which counts the number of iterations
A HOTP value length d (6–10, default is 6, and 6–8 is recommended)
Both parties compute the HOTP value derived from the secret key K and the counter C. Then the authenticator checks its locally generated value against the value supplied by the authenticated.
The authenticator and the authenticated increment the counter C independently of each other, where the latter may increase ahead of the former, thus a resynchronisation protocol is wise. does not actually require any such, but does make a recommendation. This simply has the authenticator repeatedly try verification ahead of their counter through a window of size s. The authenticator's counter continues forward of the value at which verification succeeds and requires no actions by the authenticated.
The recommendation is made that persistent throttling of HOTP value verification take place, to address their relatively small size and thus vulnerability to brute-force attacks. It is suggested that verificatio |
https://en.wikipedia.org/wiki/Old%20Baldy%20%28horse%29 | Old Baldy (ca. 1852 – December 16, 1882) was the horse ridden by Union Major General George G. Meade at the Battle of Gettysburg and in many other important battles of the American Civil War.
Early life and Civil War service
Baldy was born and raised on the western frontier and at the start of the Civil War was owned by Maj. Gen. David Hunter. His name during this period is unknown. It is said that he was wounded anywhere from five to 14 times during the war, starting at the First Battle of Bull Run, where he was struck in the nose by a piece of an artillery shell. Soon after, in September 1861, he was purchased from the government by Meade in Washington, D.C., for $150 and named Baldy because of his white face.
Despite Baldy's unusual, uncomfortable pace, Meade became quite devoted to him and rode him in all of his battles through 1862 and the spring of 1863. The horse was wounded in the right hind leg at the Second Battle of Bull Run, and at Antietam, he was wounded through the neck and left for dead on the field. He survived and was treated. At Gettysburg, on July 2, 1863, Baldy was hit by a bullet that entered his stomach after passing through Meade's right trouser leg. He staggered and refused to move forward, defying all of Meade's directions. Meade commented, "Baldy is done for this time. This is the first time he has refused to go forward under fire." Baldy was sent to the rear for recuperation. In 1864, having returned to duty for the Overland Campaign and the Siege of Petersburg, he was struck in the ribs by a shell at the Weldon Railroad, and Meade decided that Old Baldy should be retired.
Retirement and death
Baldy was sent north to Philadelphia and then to the farm of Meade's staff quartermaster, Captain Sam Ringwalt, in Downingtown, Pennsylvania. He was later relocated to the Meadow Bank Farm, owned by a friend of the Meade family, where he remained for several years. He was moderately active in retirement and Meade rode the horse in several me |
https://en.wikipedia.org/wiki/Numbers%20in%20Egyptian%20mythology | Certain numbers were considered sacred, holy, or magical by the ancient Egyptians, particularly 2, 3, 4, 7, and their multiples and sums.
Three: symbol of plurality
The basic symbol for plurality among the ancient Egyptians was the number three: even the way they wrote the word for "plurality" in hieroglyphics consisted of three vertical marks (𓏼). Triads of deities were also used in Egyptian religion to signify a complete system. Examples include references to the god Atum "when he was one and became three" when he gave birth to Shu and Tefnut, and the triad of Horus, Osiris, and Isis.
Examples
The beer used to trick Sekhmet soaked three hands into the ground.
The second god, Re, named three times to define the sun: dawn, noon, and evening.
Thoth is described as the “thrice-great god of wisdom”.
A doomed prince was doomed to three fates: to die by a crocodile, a serpent, or a dog.
Three groups of three attempts each (nine attempts) were required for a legendary peasant to recover his stolen goods.
A boasting mage claimed to be able to cast a great darkness to last three days.
After asking Thoth for help, a King of Ethiopia was brought to Thebes and publicly beaten three further times.
An Ethiopian mage tried—and failed—three times to defeat the greatest mage of Egypt.
An Egyptian mage, in an attempt to enter the land of the dead, threw a certain powder on a fire three times.
There are twelve (three times four) sections of the Egyptian land of the dead. The dead disembark at the third.
The Knot of Isis, representing life, has three loops.
Five
Examples
The second god, Rê, named five gods and goddesses.
Thoth added five days to the year by winning the light from the Moon in a game of gambling.
It took five days for the five children of Nut and Geb to be born. These are Osiris, Nephthys, Isis, Set and Haroeris (Horus the Elder) - not be mistaken with Harpocrates (Horus the Younger), who defeated Set in battle.
A boasting mage claimed to be able to bring the Ph |
https://en.wikipedia.org/wiki/List%20of%20cat%20body-type%20mutations | Cats, like all living organisms, occasionally have mutations that affect their body type. Sometimes, these mutations are striking enough that humans select for and perpetuate them. However, in relatively small or isolated feral cat populations the mutations can also spread without human intervention, for example on islands. Cat breeders exploit the naturally occurring mutations by selectively breeding them in a small gene pool, resulting in the creation of new cat breeds with unusual physical characteristics. The term designer cats is often used to refer to these cat breeds. This is not always in the best interests of the cat, as many of these mutations are harmful; some are even lethal in their homozygous form. To protect the animal’s welfare it is illegal in several countries or states to breed with parent cats that bear certain of these hypertype mutations.
This article gives a selection of cat body type mutant alleles and the associated mutations with a brief description.
Tail types
Jb Japanese Bobtail gene (autosomal dominant). Cats homozygous and heterozygous for this gene display shortened and kinked tails. Cats homozygous for the gene tend to have shorter, more kinked tails. This can be distinguished phenotypically from the Manx cat mutation by the presence of kinking in the tail, often forming what looks like a knot at the distal end of the tail. Unlike the Manx tailless gene, there are no associated skeletal disorders and the gene is not associated with lethality.
M Manx tailless gene (dominant with high penetrance). Cats with the homozygous genotype (MM) die before birth, and stillborn kittens show gross abnormalities of the central nervous system. Cats with the heterozygous genotype (Mm) show severely shortened tail length, ranging from taillessness to a partial, stumpy tail. Some Manx cats die before 12 months old and exhibit skeletal and organ defects. Because it was discovered in naturally occurring populations of cats, the Manx gene could con |
https://en.wikipedia.org/wiki/Mathematical%20Association | The Mathematical Association is a professional society concerned with mathematics education in the UK.
History
It was founded in 1871 as the Association for the Improvement of Geometrical Teaching and renamed to the Mathematical Association in 1894. It was the first teachers' subject organisation formed in England. In March 1927, it held a three-day meeting in Grantham to commemorate the bicentenary of the death of Sir Isaac Newton, attended by Sir J. J. Thomson (discoverer of the electron), Sir Frank Watson Dyson – the Astronomer Royal, Sir Horace Lamb, and G. H. Hardy.
In 1951, Mary Cartwright became the first female president of the Mathematical Association.
In the 1960s, when comprehensive education was being introduced, the Association was in favour of the 11-plus system. For maths teachers training at university, a teaching award that was examined was the Diploma of the Mathematical Association, later known as the Diploma in Mathematical Education of the Mathematical Association.
Function
It exists to "bring about improvements in the teaching of mathematics and its applications, and to provide a means of communication among students and teachers of mathematics". Since 1894 it has published The Mathematical Gazette. It is one of the participating bodies in the quadrennial British Congress of Mathematics Education, organised by the Joint Mathematical Council, and it holds its annual general meeting as part of the Congress.
Structure
It is based in the south-east of Leicester on London Road (A6), just south of the Charles Frears campus of De Montfort University.
Aside from the Council, it has seven other specialist committees.
Regions
Its branches are sometimes shared with the Association of Teachers of Mathematics (ATM):
Birmingham
Cambridge
East Midlands
Exeter
Gloucester
Liverpool
London
Greater Manchester
Meridian
Stoke and Staffordshire
Sheffield
Sussex
Yorkshire
Past presidents
Past presidents of The Association for the Improvement of |
https://en.wikipedia.org/wiki/Ibritumomab%20tiuxetan | Ibritumomab tiuxetan (pronounced ), sold under the trade name Zevalin, is a monoclonal antibody radioimmunotherapy treatment for non-Hodgkin's lymphoma. The drug uses the monoclonal mouse IgG1 antibody ibritumomab in conjunction with the chelator tiuxetan, to which a radioactive isotope (either yttrium-90 or indium-111) is added. Tiuxetan is a modified version of DTPA whose carbon backbone contains an isothiocyanatobenzyl and a methyl group.
Medical use
Ibritumomab is used to treat relapsed or refractory, low grade or transformed B cell non-Hodgkin's lymphoma (NHL), a lymphoproliferative disorder, and previously untreated follicular NHL in adult patients who achieve a partial or complete response to first-line chemotherapy. The treatment should not be administered to patients with ≥25% lymphoma marrow involvement and/or impaired bone marrow reserve.
The treatment starts with an infusions of rituximab. This may be followed by an administration of indium-111 labelled ibritumomab tiuxetan (111In replaces the 90Y component) to allow the distribution of the drug to be imaged on a gamma camera, before the actual therapy is administered. Seven to nine days later, a second infusion of rituximab is given, followed by the 90Y-ibritumomab tiuxetan, by intravenous infusion over around 10 minutes. The radioactive activity is determined based on patient body weight and platelet count.
Mechanism of action
The antibody binds to the CD20 antigen found on the surface of normal and malignant B cells (but not B cell precursors), allowing radiation from the attached isotope (mostly beta emission) to kill it and some nearby cells. In addition, the antibody itself may trigger cell death via antibody-dependent cell-mediated cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and apoptosis. Together, these actions eliminate B cells from the body, allowing a new population of healthy B cells to develop from lymphoid stem cells.
History
Developed by the IDEC Pharmaceuticals, now |
https://en.wikipedia.org/wiki/Atmospheric%20escape | Atmospheric escape is the loss of planetary atmospheric gases to outer space. A number of different mechanisms can be responsible for atmospheric escape; these processes can be divided into thermal escape, non-thermal (or suprathermal) escape, and impact erosion. The relative importance of each loss process depends on the planet's escape velocity, its atmosphere composition, and its distance from its star. Escape occurs when molecular kinetic energy overcomes gravitational energy; in other words, a molecule can escape when it is moving faster than the escape velocity of its planet. Categorizing the rate of atmospheric escape in exoplanets is necessary to determining whether an atmosphere persists, and so the exoplanet's habitability and likelihood of life.
Thermal escape mechanisms
Thermal escape occurs if the molecular velocity due to thermal energy is sufficiently high. Thermal escape happens at all scales, from the molecular level (Jeans escape) to bulk atmospheric outflow (hydrodynamic escape).
Jeans escape
One classical thermal escape mechanism is Jeans escape, named after British astronomer Sir James Jeans, who first described this process of atmospheric loss. In a quantity of gas, the average velocity of any one molecule is measured by the gas's temperature, but the velocities of individual molecules change as they collide with one another, gaining and losing kinetic energy. The variation in kinetic energy among the molecules is described by the Maxwell distribution. The kinetic energy (), mass (), and velocity () of a molecule are related by . Individual molecules in the high tail of the distribution (where a few particles have much higher speeds than the average) may reach escape velocity and leave the atmosphere, provided they can escape before undergoing another collision; this happens predominantly in the exosphere, where the mean free path is comparable in length to the pressure scale height. The number of particles able to escape depends on the mol |
https://en.wikipedia.org/wiki/Toile | Toile (French for "canvas") is a textile fabric comparable to fine batiste with a cloth weave. Natural silk or chemical fiber filaments are usually used as materials. The word toile can refer to the fabric itself or to a test garment sewn from calico. The French term toile entered the English language around the 12th century, was used in the middle ages and meanwhile has disappeared.
Etymology
Middle English toile, from French toile ("cloth"), from Old French teile, from Latin tela ("web"), from Proto-Indo-European *(s)teg ("to cover") (see List of Proto-Indo-European roots in Wiktionary). In Australian and British terminology, a toile is a version of a garment made by a fashion designer or dressmaker to test a pattern. They are usually made of calico, as multiple toiles may be made in the process of perfecting a design. In the United States toiles are sometimes referred to as muslins, because during the Middle Ages they were made from the cheap, unbleached muslin-fabric available in different weights.
Toile de Jouy
The French "Toile de Jouy" simply means "cloth from Jouy" in English and describes a type of fabric printing.
"Toile de Jouy", sometimes abbreviated to simply "toile", is a type of decorating pattern consisting of a white or off-white background on which is a repeated pattern depicting a fairly complex scene, generally of a pastoral theme such as a couple having a picnic by a lake or an arrangement of flowers. The pattern portion consists of a single color, most often black, dark red, or blue. Greens, browns, and magenta toile patterns are less common, but not unheard of. Toile is most associated with fabrics (curtains and upholstery in particular, especially chintz), though toile wallpaper is also popular. Toile can also be used on teapots, beddings, clothing, etc. In upper-class (primarily American, but also northern European) society, toile is often seen on dresses or aprons used at such events as country-themed garden parties or tea parties.
To |
https://en.wikipedia.org/wiki/DPLL%20algorithm | In logic and computer science, the Davis–Putnam–Logemann–Loveland (DPLL) algorithm is a complete, backtracking-based search algorithm for deciding the satisfiability of propositional logic formulae in conjunctive normal form, i.e. for solving the CNF-SAT problem.
It was introduced in 1961 by Martin Davis, George Logemann and Donald W. Loveland and is a refinement of the earlier Davis–Putnam algorithm, which is a resolution-based procedure developed by Davis and Hilary Putnam in 1960. Especially in older publications, the Davis–Logemann–Loveland algorithm is often referred to as the "Davis–Putnam method" or the "DP algorithm". Other common names that maintain the distinction are DLL and DPLL.
Implementations and applications
The SAT problem is important both from theoretical and practical points of view. In complexity theory it was the first problem proved to be NP-complete, and can appear in a broad variety of applications such as model checking, automated planning and scheduling, and diagnosis in artificial intelligence.
As such, writing efficient SAT solvers has been a research topic for many years. GRASP (1996-1999) was an early implementation using DPLL. In the international SAT competitions, implementations based around DPLL such as zChaff and MiniSat were in the first places of the competitions in 2004 and 2005.
Another application that often involves DPLL is automated theorem proving or satisfiability modulo theories (SMT), which is a SAT problem in which propositional variables are replaced with formulas of another mathematical theory.
The algorithm
The basic backtracking algorithm runs by choosing a literal, assigning a truth value to it, simplifying the formula and then recursively checking if the simplified formula is satisfiable; if this is the case, the original formula is satisfiable; otherwise, the same recursive check is done assuming the opposite truth value. This is known as the splitting rule, as it splits the problem into two simpler sub-p |
https://en.wikipedia.org/wiki/X-ray%20absorption%20spectroscopy | X-ray absorption spectroscopy (XAS) is a widely used technique for determining the local geometric and/or electronic structure of matter. The experiment is usually performed at synchrotron radiation facilities, which provide intense and tunable X-ray beams. Samples can be in the gas phase, solutions, or solids.
Background
XAS data is obtained by tuning the photon energy, using a crystalline monochromator, to a range where core electrons can be excited (0.1-100 keV). The edges are, in part, named by which core electron is excited: the principal quantum numbers n = 1, 2, and 3, correspond to the K-, L-, and M-edges, respectively. For instance, excitation of a 1s electron occurs at the K-edge, while excitation of a 2s or 2p electron occurs at an L-edge (Figure 1).
There are three main regions found on a spectrum generated by XAS data which are then thought of as separate spectroscopic techniques (Figure 2):
The absorption threshold determined by the transition to the lowest unoccupied states:
The X-ray absorption near-edge structure (XANES), introduced in 1980 and later in 1983 and also called NEXAFS (near-edge X-ray absorption fine structure), which are dominated by core transitions to quasi bound states (multiple scattering resonances) for photoelectrons with kinetic energy in the range from 10 to 150 eV above the chemical potential, called "shape resonances" in molecular spectra since they are due to final states of short life-time degenerate with the continuum with the Fano line-shape. In this range multi-electron excitations and many-body final states in strongly correlated systems are relevant;
In the high kinetic energy range of the photoelectron, the scattering cross-section with neighbor atoms is weak, and the absorption spectra are dominated by EXAFS (extended X-ray absorption fine structure), where the scattering of the ejected photoelectron of neighboring atoms can be approximated by single scattering events. In 1985, it was shown that multiple scat |
https://en.wikipedia.org/wiki/Blusher | The blusher is the common name for several closely related species of the genus Amanita. A. rubescens or the blushing amanita, is found in Europe and eastern North America, and A. novinupta, also known as the new bride blushing amanita, is found in western North America. Both their scientific and common names are derived from the propensity of their flesh to turn pink on bruising, or cutting.
The mushroom is edible and tasty, sought for in several European countries. It may however easily be confused with the potentially deadly panther cap by inexperienced foragers, and guides advise extreme caution when collecting this species. Blushers can be distinguished from similar species by the pink or reddish colouration that appears when the mushroom is damaged, typically most visible at the base of the stipe from insect damage.
Description
The European blusher has a reddish-brown convex pileus (cap), that is 5–15 cm across, and strewn with small white-to-mahogany warts. It is sometimes covered with an ochre-yellow flush which can be washed by the rain. The flesh of the mushroom is white, becoming pink when bruised or exposed to air. This is a key feature in differentiating it from the poisonous false blusher or panther cap (Amanita pantherina), whose flesh does not. The stipe (stem) is white with flushes of the cap colour, and grows to 5–15 cm. The gills are white and free of the stem, and display red spots when damaged.
The ring is striate (i.e. has ridges) on its upper side, another feature distinguishing it from Amanita pantherina.
The spores are white, ovate, amyloid, and approximately 8 by 5 µm in size.
The flavour of the uncooked flesh is mild, but has a faint acrid aftertaste. The smell is not strong.
The mushroom is often attacked by insects.
Distribution and habitat
It is common throughout much of Europe and eastern North America (in the latter region there are at least three different species that fit into the name Amanita amerirubescens) growing on poor |
https://en.wikipedia.org/wiki/American%20National%20Corpus | The American National Corpus (ANC) is a text corpus of American English containing 22 million words of written and spoken data produced since 1990. Currently, the ANC includes a range of genres, including emerging genres such as email, tweets, and web data that are not included in earlier corpora such as the British National Corpus. It is annotated for part of speech and lemma, shallow parse, and named entities.
The ANC is available from the Linguistic Data Consortium. A fifteen million word subset of the corpus, called the Open American National Corpus (OANC), is freely available with no restrictions on its use from the ANC Website.
The corpus and its annotations are provided according to the specifications of ISO/TC 37 SC4's Linguistic Annotation Framework. By using a freely provided transduction tool (ANC2Go), the corpus and user-chosen annotations are provided in multiple formats, including CoNLL IOB format, the XML format conformant to the XML Corpus Encoding Standard (XCES) (usable with the British National Corpus's XAIRA search engine), a UIMA-compliant format, and formats suitable for input to a wide variety of concordance software. Plugins to import the annotations into General Architecture for Text Engineering (GATE) are also available.
The ANC differs from other corpora of English because it is richly annotated, including different part of speech annotations (Penn tags, CLAWS5 and CLAWS7 tags), shallow parse annotations, and annotations for several types of named entities. Additional annotations are added to all or parts of the corpus as they become available, often by contributions from other projects. Unlike on-line searchable corpora, which due to copyright restrictions allow access only to individual sentences, the entire ANC is available to enable research involving, for example, development of statistical language models and full-text linguistic annotation.
ANC annotations are automatically produced and unvalidated.
A 500,000 word subset call |
https://en.wikipedia.org/wiki/Turbo%20Dispatch | Turbo Dispatch is a public domain standard for the electronic transfer of job details, initially using packet radio, but now also using the internet. It is used throughout the United Kingdom to pass the details of stranded motorists between all the major UK motoring organisations and their 400 plus vehicle recovery agents. In many cases it is also used by the vehicle recovery agent to pass the details to the attending recovery vehicle.
History
On 30 June 1994, a group of representatives from the UK seven major motoring organisations and the Institute of Vehicle Recovery were invited a meeting at Brooklands Museum. Brooklands Museum was chosen as the venue because the meeting's chairman Andy Lambert was involved with the museum, having transported the vast majority of the exhibits there, and could therefore show people items they would not normally get to see. He clearly hoped that this would be enough incentive to get ‘the clubs’ to sit-down in the same room together. It soon emerged that it was a shared dream of all those present that ‘common standards’ for all aspects of vehicle recovery could be introduced to the industry. Amongst other things, this group laid the foundations of Turbo Dispatch project.
Because of the reliability of delivery needed it was decided that Mobitex should be used. In the UK there was only one provider of Mobitex, namely RAM Data, which later became a subsidiary of BT called Transcomm. This is why many users still refer to RAMing jobs. Ian Lane of Motor Trade Software (MTS) designed and wrote the protocols along with the gateway software. Much pioneering work was carried out during early 1995. In the autumn of 1995 Green Flag and Delta Rescue were the first motoring organisations to start experimenting with transmissions to the garages, with the first genuine job being sent to Southbank Garage at the end of the year.
The point where most recovery operators learned about Turbo Dispatch was during the Association of Vehicle Recovery O |
https://en.wikipedia.org/wiki/Articulated%20robot | An articulated robot is a robot with rotary joints (e.g. a legged robot or an industrial robot). Articulated robots can range from simple two-jointed structures to systems with 10 or more interacting joints and materials.
They are powered by a variety of means, including electric motors.
Some types of robots, such as robotic arms, can be articulated or non-articulated.
Articulated robots in action
Definitions
Articulated Robot:
See Figure. An articulated robot uses all the three revolute joints to access its work space.
Usually the joints are arranged in a “chain”, so that one joint supports another further in the chain.
Continuous Path:
A control scheme whereby the inputs or commands specify every point along a desired path of motion. The path is controlled by the coordinated motion of the manipulator joints.
Degrees Of Freedom (DOF):
The number of independent motions in which the end effector can move, defined by the number of axes of motion of the manipulator.
Gripper:
A device for grasping or holding, attached to the free end of the last manipulator link; also called the robot’s hand or end-effector.
Payload:
The maximum payload is the amount of weight carried by the robot manipulator at reduced speed while maintaining rated precision. Nominal payload is measured at maximum speed while maintaining rated precision. These ratings are highly dependent on the size and shape of the payload.
Pick And Place Cycle:
See Figure. Pick and place Cycle is the time, in seconds, to execute the following motion sequence: Move down one inch, grasp a rated payload; move up one inch; move across twelve inches; move down one inch; ungrasp; move up one inch; and return to start location.
Reach:
The maximum horizontal distance from the center of the robot base to the end of its wrist.
Accuracy:
See Figure. The difference between the point that a robot is trying to achieve and the actual resultant position. Absolute accuracy is the difference between a point instructed by |
https://en.wikipedia.org/wiki/Equilibrium%20thermodynamics | Equilibrium Thermodynamics is the systematic study of transformations of matter and energy in systems in terms of a concept called thermodynamic equilibrium. The word equilibrium implies a state of balance. Equilibrium thermodynamics, in origins, derives from analysis of the Carnot cycle. Here, typically a system, as cylinder of gas, initially in its own state of internal thermodynamic equilibrium, is set out of balance via heat input from a combustion reaction. Then, through a series of steps, as the system settles into its final equilibrium state, work is extracted.
In an equilibrium state the potentials, or driving forces, within the system, are in exact balance. A central aim in equilibrium thermodynamics is: given a system in a well-defined initial state of thermodynamic equilibrium, subject to accurately specified constraints, to calculate, when the constraints are changed by an externally imposed intervention, what the state of the system will be once it has reached a new equilibrium. An equilibrium state is mathematically ascertained by seeking the extrema of a thermodynamic potential function, whose nature depends on the constraints imposed on the system. For example, a chemical reaction at constant temperature and pressure will reach equilibrium at a minimum of its components' Gibbs free energy and a maximum of their entropy.
Equilibrium thermodynamics differs from non-equilibrium thermodynamics, in that, with the latter, the state of the system under investigation will typically not be uniform but will vary locally in those as energy, entropy, and temperature distributions as gradients are imposed by dissipative thermodynamic fluxes. In equilibrium thermodynamics, by contrast, the state of the system will be considered uniform throughout, defined macroscopically by such quantities as temperature, pressure, or volume. Systems are studied in terms of change from one equilibrium state to another; such a change is called a thermodynamic process.
|
https://en.wikipedia.org/wiki/Thermodynamic%20state | In thermodynamics, a thermodynamic state of a system is its condition at a specific time; that is, fully identified by values of a suitable set of parameters known as state variables, state parameters or thermodynamic variables. Once such a set of values of thermodynamic variables has been specified for a system, the values of all thermodynamic properties of the system are uniquely determined. Usually, by default, a thermodynamic state is taken to be one of thermodynamic equilibrium. This means that the state is not merely the condition of the system at a specific time, but that the condition is the same, unchanging, over an indefinitely long duration of time.
Thermodynamics sets up an idealized conceptual structure that can be summarized by a formal scheme of definitions and postulates. Thermodynamic states are amongst the fundamental or primitive objects or notions of the scheme, for which their existence is primary and definitive, rather than being derived or constructed from other concepts.
A thermodynamic system is not simply a physical system. Rather, in general, infinitely many different alternative physical systems comprise a given thermodynamic system, because in general a physical system has vastly many more microscopic characteristics than are mentioned in a thermodynamic description. A thermodynamic system is a macroscopic object, the microscopic details of which are not explicitly considered in its thermodynamic description. The number of state variables required to specify the thermodynamic state depends on the system, and is not always known in advance of experiment; it is usually found from experimental evidence. The number is always two or more; usually it is not more than some dozen. Though the number of state variables is fixed by experiment, there remains choice of which of them to use for a particular convenient description; a given thermodynamic system may be alternatively identified by several different choices of the set of state variables. |
https://en.wikipedia.org/wiki/Shrimp%20on%20the%20barbie | "Shrimp on the barbie" is a phrase that originated in a series of television advertisements by the Australian Tourism Commission broadcast in the US and UK starring Paul Hogan from 1984 through to 1990. The full quote spoken by Hogan is "I'll slip an extra shrimp on the barbie for you", and the actual slogan of the ad was "". It has since been used, along with some variations, to make reference to Australia in popular culture, however the phrase is rarely actually used in Australia. Very few use the word 'shrimp' in Australia (the word most commonly used is 'prawn') and the phrase is often perceived as American.
Details
The advertisement pre-dated Hogan's popularity in the 1986 film Crocodile Dundee. Thus they were not initially seen as celebrity advertisements in the US, as he was relatively unknown in the United States (though well known in the UK through his long-running television comedy show), although the film somewhat increased the commercial's popularity.
The advertisements were developed by the Australian agency Mojo in conjunction with American agency N.W. Ayer. The campaign was launched during the National Football Conference Championship Game on 8 January 1984. Before the campaign, Australia was approximately number 78 on the "most desired" vacation destination list for Americans, but became number 7 three months after the launch, and soon became number 1 or 2 on Americans' "dream vacation" list, remaining in that position for most of the next two decades.
"" is Australian slang for barbecue and the phrase "slip a shrimp on the barbie" often evokes images of a fun social gathering under the sun. Australians, however, invariably use the word rather than shrimp. Because the commercial was commissioned for broadcast in the United States, the change was made to limit audience confusion. The commercial was so influential that three decades later, Australian USC Trojans football player Chris Tilbey reported that he was quoted the "shrimp on the barbie" lin |
https://en.wikipedia.org/wiki/Biological%20thermodynamics | Biological thermodynamics (Thermodynamics of biological systems) is a science that explains the nature and general laws of thermodynamic processes occurring in living organisms as nonequilibrium thermodynamic systems that convert the energy of the Sun and food into other types of energy. The nonequilibrium thermodynamic state of living organisms is ensured by the continuous alternation of cycles of controlled biochemical reactions, accompanied by the release and absorption of energy, which provides them with the properties of phenotypic adaptation and a number of others.
History
In 1935, the first scientific work devoted to the thermodynamics of biological systems was published - the book of the Hungarian-Russian theoretical biologist Erwin S. Bauer (1890-1938) "Theoretical Biology"[]. E. Bauer formulated the "Universal Law of Biology" in the following edition: "All and only living systems are never in equilibrium and perform constant work at the expense of their free energy against the equilibrium required by the laws of physics and chemistry under existing external conditions". This law can be considered the 1st law of thermodynamics of biological systems.
In 1957, German-British physician and biochemist Hans Krebs and British-American biochemist Hans Kornberg[] in the book "Energy Transformations in Living Matter" first described the thermodynamics of biochemical reactions. In their works, H. Krebs and Hans Kornberg showed how in living cells, as a result of biochemical reactions, adenosine triphosphate (ATP) is synthesized from food, which is the main source of energy of living organisms (the Krebs–Kornberg cycle).
In 2006, the Israeli-Russian scientist Boris Dobroborsky (1945) published the book "Thermodynamics of Biological Systems"[], in which the general principles of functioning of living organisms from the perspective of nonequilibrium thermodynamics were formulated for the first time and the nature and properties of their basic physiological function |
https://en.wikipedia.org/wiki/Gramicidin%20S | Gramicidin S or Gramicidin Soviet is an antibiotic that is effective against some gram-positive and gram-negative bacteria as well as some fungi.
It is a derivative of gramicidin, produced by the gram-positive bacterium Brevibacillus brevis. Gramicidin S is a cyclodecapeptide, constructed as two identical pentapeptides joined head to tail, formally written as cyclo(-Val-Orn-Leu-D-Phe-Pro-)2. That is to say, it forms a ring structure composed of five different amino acids, each one used twice within the structure. Another interesting point is that it utilizes two amino acids uncommon in peptides: ornithine as well as the atypical stereoisomer of phenylalanine. It is synthesized by gramicidin S synthetase.
Biosynthesis
Gramicidin S biosynthetic pathway consists of two-enzyme of nonribosomal peptide synthases (NRPSs), gramicidin S synthetase I (GrsA) and gramicidin S synthetase II (GrsB), to give a product as a cyclic decapeptide. Within the biosynthetic pathway, there are total of five modules that specifically recognize, activate, and condense the amino acids to gramicidin S. Starting module GrsA consists of three domains: Adenylation (A) domain where it incorporates the amino acid and activates it by adenylation using ATP, Thiolation (T) domain or peptidyl carrier protein (PCP) in which the adenylated amino acid gets covalently attached to the 4´-phosphopantetheine group and this gets loaded onto the conserved serine in the T domain, Epimerization (E) domain where it epimerizes L-amino acid to D-amino acid. Starting module GrsA loads D-Phe onto the system.
Second enzyme cluster GrsB contains four modules, each containing condensation (C), adenylation (A), and thiolation (T) domains and thioesterase domain (TE) at the end. C domain forms a peptide bond between two amino acids, D-Phe and L-Pro. L-Val, L-Orn, and L-Leu are incorporated sequentially by the next three modules of GrsB. After repeating the whole module synthesis once again, TE domain cyclizes and rel |
https://en.wikipedia.org/wiki/Synergetics%20%28Haken%29 | Synergetics is an interdisciplinary science explaining the formation and self-organization of patterns and structures in open systems far from thermodynamic equilibrium. It is founded by Hermann Haken, inspired by the laser theory. Haken's interpretation of the laser principles as self-organization of non-equilibrium systems paved the way at the end of the 1960s to the development of synergetics. One of his successful popular books is Erfolgsgeheimnisse der Natur, translated into English as The Science of Structure: Synergetics.
Self-organization requires a 'macroscopic' system, consisting of many nonlinearly interacting subsystems. Depending on the external control parameters (environment, energy fluxes) self-organization takes place.
Order-parameter concept
Essential in synergetics is the order-parameter concept which was originally introduced in the Ginzburg–Landau theory in order to describe phase transitions in thermodynamics. The order parameter concept is generalized by Haken to the "enslaving-principle" saying that the dynamics of fast-relaxing (stable) modes is completely determined by the 'slow' dynamics of, as a rule, only a few 'order-parameters' (unstable modes). The order parameters can be interpreted as the amplitudes of the unstable modes determining the macroscopic pattern.
As a consequence, self-organization means an enormous reduction of degrees of freedom (entropy) of the system which macroscopically reveals an increase of 'order' (pattern-formation). This far-reaching macroscopic order is independent of the details of the microscopic interactions of the subsystems. This supposedly explains the self-organization of patterns in so many different systems in physics, chemistry and biology.
See also
Effective field theory
Josiah Willard Gibbs
Phase rule
Free energy principle
Fokker–Planck equation
Ginzburg–Landau theory
Buckminster Fuller
Alexander Bogdanov
Abiogenesis |
https://en.wikipedia.org/wiki/Jock%20Tamson%27s%20bairns | "Jock Tamson's bairns" is a Scots (and Northumbrian English) dialect version of "Jack (John) Thomson's children" but both Jock and Tamson in this context take on the connotation of Everyman. The Dictionary of the Scots Language gives the following definitions:
Jock: (1) A generic term for a man, a male person. (34) Jock Tamson's bairns: the human race, common humanity; also, with less universal force, a group of people united by a common sentiment, interest or purpose.
Tamson: a Scottish form of the surname Thomson. In phrases Tamson stands for the ordinary representative man in the street: Jock Tamson's bairns, common humanity.
The phrase is used in common speech in Scotland and it also occurs in general culture. Some examples are: the play of that name by Liz Lochhead;
a folk music group of that name;
the title of a book describing the official records of the Scottish nation;
parliamentary speeches by Winnie Ewing and Patrick Harvie
and Morag Alexander, the Scottish Commissioner of the Equality and Human Rights Commission (EHRC).
The phrase more often occurs in an extended form: We're a' Jock Tamson's bairns. This is interpreted in a metaphorical sense as a statement of egalitarian sentiments
equivalent to "we're all the same under the skin" or "we are all God's children".
The origin of the phrase is uncertain. The earliest reference quoted in the Dictionary of the Scots Language is from 1847 where it describes the phrase as "an expression of mutual good fellowship very frequently heard in Scotland." One suggestion is that it was simply common usage in the Fife town of Buckhaven which had 70 Thomson families out of a total of 160 families in 1833. Another is that the Reverend John Thomson, minister of Duddingston Kirk, Edinburgh, from 1805 to 1840, called the members of his congregation (and his many children) "ma bairns". The latter saying may well be the reason for the location of the plaque illustrated above.
The equivalent phrase in Scottish Gaelic is |
https://en.wikipedia.org/wiki/Quasi-invariant%20measure | In mathematics, a quasi-invariant measure μ with respect to a transformation T, from a measure space X to itself, is a measure which, roughly speaking, is multiplied by a numerical function of T. An important class of examples occurs when X is a smooth manifold M, T is a diffeomorphism of M, and μ is any measure that locally is a measure with base the Lebesgue measure on Euclidean space. Then the effect of T on μ is locally expressible as multiplication by the Jacobian determinant of the derivative (pushforward) of T.
To express this idea more formally in measure theory terms, the idea is that the Radon–Nikodym derivative of the transformed measure μ′ with respect to μ should exist everywhere; or that the two measures should be equivalent (i.e. mutually absolutely continuous):
That means, in other words, that T preserves the concept of a set of measure zero. Considering the whole equivalence class of measures ν, equivalent to μ, it is also the same to say that T preserves the class as a whole, mapping any such measure to another such. Therefore, the concept of quasi-invariant measure is the same as invariant measure class.
In general, the 'freedom' of moving within a measure class by multiplication gives rise to cocycles, when transformations are composed.
As an example, Gaussian measure on Euclidean space Rn is not invariant under translation (like Lebesgue measure is), but is quasi-invariant under all translations.
It can be shown that if E is a separable Banach space and μ is a locally finite Borel measure on E that is quasi-invariant under all translations by elements of E, then either dim(E) < +∞ or μ is the trivial measure μ ≡ 0.
See also |
https://en.wikipedia.org/wiki/Quasiconformal%20mapping | In mathematical complex analysis, a quasiconformal mapping, introduced by and named by , is a homeomorphism between plane domains which to first order takes small circles to small ellipses of bounded eccentricity.
Intuitively, let f : D → D′ be an orientation-preserving homeomorphism between open sets in the plane. If f is continuously differentiable, then it is K-quasiconformal if the derivative of f at every point maps circles to ellipses with eccentricity bounded by K.
Definition
Suppose f : D → D′ where D and D′ are two domains in C. There are a variety of equivalent definitions, depending on the required smoothness of f. If f is assumed to have continuous partial derivatives, then f is quasiconformal provided it satisfies the Beltrami equation
for some complex valued Lebesgue measurable μ satisfying sup |μ| < 1 . This equation admits a geometrical interpretation. Equip D with the metric tensor
where Ω(z) > 0. Then f satisfies () precisely when it is a conformal transformation from D equipped with this metric to the domain D′ equipped with the standard Euclidean metric. The function f is then called μ-conformal. More generally, the continuous differentiability of f can be replaced by the weaker condition that f be in the Sobolev space W1,2(D) of functions whose first-order distributional derivatives are in L2(D). In this case, f is required to be a weak solution of (). When μ is zero almost everywhere, any homeomorphism in W1,2(D) that is a weak solution of () is conformal.
Without appeal to an auxiliary metric, consider the effect of the pullback under f of the usual Euclidean metric. The resulting metric is then given by
which, relative to the background Euclidean metric , has eigenvalues
The eigenvalues represent, respectively, the squared length of the major and minor axis of the ellipse obtained by pulling back along f the unit circle in the tangent plane.
Accordingly, the dilatation of f at a point z is defined by
The (essential) supremum |
https://en.wikipedia.org/wiki/Crossed%20product | In mathematics, and more specifically in the theory of von Neumann algebras, a crossed product
is a basic method of constructing a new von Neumann algebra from
a von Neumann algebra acted on by a group. It is related to
the semidirect product construction for groups. (Roughly speaking, crossed product is the expected structure for a group ring of a semidirect product group. Therefore crossed products have a ring theory aspect also. This article concentrates on an important case, where they appear in functional analysis.)
Motivation
Recall that if we have two finite groups and N with an action of G on N we can form the semidirect product . This contains N
as a normal subgroup, and the action of G on N is given by conjugation in the semidirect product. We can replace N by its complex group algebra C[N], and again form a product in a similar way; this algebra is a sum of subspaces gC[N] as g runs through the elements of G, and is the group algebra of .
We can generalize this construction further by replacing C[N]
by any algebra A acted on by G to get a crossed product
, which is the sum of subspaces
gA and where the action of G on A is given by conjugation in the crossed product.
The crossed product of a von Neumann algebra by a group G acting on it is similar except that we have to be more careful about topologies, and need to construct a Hilbert space acted on by the crossed product. (Note that the von Neumann algebra crossed product is usually larger than the algebraic crossed product discussed above; in fact it is some sort of completion of the algebraic crossed product.)
In physics, this structure appears in presence of the so called gauge group of the first kind. G is the gauge group, and N the "field" algebra. The observables are then defined as the fixed points of N under the action of G. A result by Doplicher, Haag and Roberts says that under some assumptions the crossed product can be recovered from the algebra of observables.
Construction
Suppose th |
https://en.wikipedia.org/wiki/Tait%20conjectures | The Tait conjectures are three conjectures made by 19th-century mathematician Peter Guthrie Tait in his study of knots. The Tait conjectures involve concepts in knot theory such as alternating knots, chirality, and writhe. All of the Tait conjectures have been solved, the most recent being the Flyping conjecture.
Background
Tait came up with his conjectures after his attempt to tabulate all knots in the late 19th century. As a founder of the field of knot theory, his work lacks a mathematically rigorous framework, and it is unclear whether he intended the conjectures to apply to all knots, or just to alternating knots. It turns out that most of them are only true for alternating knots. In the Tait conjectures, a knot diagram is called "reduced" if all the "isthmi", or "nugatory crossings" have been removed.
Crossing number of alternating knots
Tait conjectured that in certain circumstances, crossing number was a knot invariant, specifically:
Any reduced diagram of an alternating link has the fewest possible crossings.
In other words, the crossing number of a reduced, alternating link is an invariant of the knot. This conjecture was proved by Louis Kauffman, Kunio Murasugi (村杉 邦男), and Morwen Thistlethwaite in 1987, using the Jones polynomial.
A geometric proof, not using knot polynomials, was given in 2017 by Joshua Greene.
Writhe and chirality
A second conjecture of Tait:
An amphicheiral (or acheiral) alternating link has zero writhe.
This conjecture was also proved by Kauffman and Thistlethwaite.
Flyping
The Tait flyping conjecture can be stated:
Given any two reduced alternating diagrams and of an oriented, prime alternating link: may be transformed to by means of a sequence of certain simple moves called flypes.
The Tait flyping conjecture was proved by Thistlethwaite and William Menasco in 1991.
The Tait flyping conjecture implies some more of Tait's conjectures:
Any two reduced diagrams of the same alternating knot have the same writhe.
This follo |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.