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47,565,724 | https://en.wikipedia.org/wiki/Seiffert%27s%20spiral | Seiffert's spherical spiral is a curve on a sphere made by moving on the sphere with constant speed and angular velocity with respect to a fixed diameter. If the selected diameter is the line from the north pole to the south pole, then the requirement of constant angular velocity means that the longitude of the moving point changes at a constant rate. The cylindrical coordinates of the varying point on this curve are given by the Jacobian elliptic functions.
Formulation
Symbols
Representation via equations
The Seiffert's spherical spiral can be expressed in cylindrical coordinates as
or expressed as Jacobi theta functions
.
See also
Rhumb line
References
External links
Spirals
Spherical curves | Seiffert's spiral | Mathematics | 131 |
57,130,045 | https://en.wikipedia.org/wiki/Skeletocutis%20kuehneri | Skeletocutis kuehneri is a species of poroid crust fungus in the family Polyporaceae. It was described as new to science by Alix David in 1982. The holotype was collected in France, where it was found growing on pine. It has been recorded from Norway, Finland, and Sweden, although it is rare in the Nordic countries. The fungus is a successor species, and prefers growing on pine that has been previously degraded by Trichaptum fungi, particularly T. abietinum.
References
Fungi described in 1982
Fungi of Europe
kuehneri
Fungus species | Skeletocutis kuehneri | Biology | 124 |
3,607,610 | https://en.wikipedia.org/wiki/Recoil%20buffer | A recoil buffer is a factory-installed or aftermarket component of firearms which serves to reduce the velocity and/or cushion the impact of recoiling parts of a firearm.
Design
The simplest form of recoil buffer is made from a resilient and deformable material (leather, rubber, polymer e.g. a rubber butt pad on a shotgun). A second way of producing a recoil buffer is to insert a spring into the recoil train—the path/part(s) generating recoil impulse. This spring is mounted to the point(s) where the firearm contacts a mechanical holder such as a tripod or human upper torso. Reducing the initial jolt, the rate and/or extent of rearward displacement, and any internal impacts in the operating parts of a firearm can reduce the shooter's perception of recoil, and may also work to extend the life of the mechanism and its parts. More sophisticated designs use hydraulic or pneumatic shock absorbers; systems of springs, cams and levers to modify, dampen, or dissipate the rearward impulse generated as the projectile is fired down the bore of the firearm. Aftermarket buffers are often moulded bumpers or additional springs placed between operating metal parts which impact one another, such as the slide and the frame of a semi-automatic pistol. This type of buffer cushions the battering force of repeated metal on metal impact, reducing wear on parts and lengthening the service life of the firearm. Reduction of perceived recoil discomfort is an immediate added benefit of this type of recoil buffer.
Some pneumatic recoil buffers used in firearms are fast, low-power gas springs. When compressed, they present initial resistance as the rod-to-seal grip is broken and then they move in a regular manner. An additional small spring can be used inside the gas spring if rapid turnaround times are needed. Coil-type springs twist and the coils try to ride over each other when moving and this chaotic movement does not exist with gas springs, hence reducing twist and jump of the firearm. These features are very advantageous. Fine tuning of the spring power is also possible by altering the internal gas volume. This design for firearms was invented and patented by Collins and Shipman of Bedford, UK and Bergstrom in the U.S. in 2001.
Controversy
There is some debate as to whether or not buffers really reduce recoil, with some arguing they actually increase it and, in addition, cause malfunctions of the firearm. This debate mainly occurs with guns that weren't originally designed for recoil buffers, such as the M1911 and AK-47, but has also extended to designs that included them originally. The counter argument generally is that if the buffer is made out of proper materials, it can absorb the recoil instead of transferring it, and that most malfunctions are caused by cheap plastic buffers.
See also
Glossary of firearms terms
Firearm components
Firearm terminology
Glossary of military abbreviations
List of established military terms
References
External links
Firearm components | Recoil buffer | Technology | 613 |
61,314,883 | https://en.wikipedia.org/wiki/Centre%20for%20Digital%20Built%20Britain | The Centre for Digital Built Britain (CDBB) was a partnership between the University of Cambridge and UK's Department for Business, Energy and Industry Strategy. The CDBB was established in 2017 to support the transformation of the UK built environment using digital technologies to better design, build, maintain and integrate assets. Prior to its closure in March 2022, it was the home of the UK BIM programme, begun by the UK BIM Task Group (2011-2017), and the National Digital Twin programme.
History
In May 2011, UK Government Chief Construction Adviser Paul Morrell called for adoption of Building Information Modelling (BIM) on UK government construction projects. The UK BIM Task Group was a UK Government-funded group, managed through the Cabinet Office, and created in 2011. Chaired by Mark Bew, it was founded to "drive adoption of BIM across government" in support of the Government Construction Strategy. It led the government's BIM programme and requirements, including a free-to-use set of UK standards and tools that defined 'level 2 BIM'. The BIM Task Group later took responsibility for delivering the Digital Built Britain strategy, published in February 2015.
The work of the BIM Task Group continued under the stewardship of the Cambridge-based Centre for Digital Built Britain, announced by the Department for Business, Innovation and Skills in December 2017 and formally launched in early 2018. Its role was to support the transformation of the UK's construction sector using digital technologies to better plan, build, maintain and use infrastructure.
In October 2019, the CDBB, the UK BIM Alliance (renamed 'nima' in 2022) and the BSI Group launched the UK BIM Framework. Superseding the BIM levels approach, the framework describes an overarching approach to implementing BIM in the UK, integrating the international ISO 19650 series of standards into UK processes and practice.
In March 2022, the CDBB completed its mission, passing the Digital Twin Hub, International Programme, and Climate Resilience Demonstrator to the Connected Places Catapult. The final research projects within the Construction Innovation Hub Programme will complete by September 2022.
Structure and work
The CDBB was led by Professor Andy Neely, building on the work of the Cambridge Centre for Smart Infrastructure and Construction (CSIC), Cambridge Big Data, the Distributed Information and Automation Lab, the Cambridge Service Alliance and the Institute for Manufacturing. The CDBB was based in the CSIC's facility, the Maxwell Centre, in West Cambridge.
The CDBB was a member of the Construction Innovation Hub, alongside the Building Research Establishment and the Manufacturing Technology Centre, and collaborated with other partners in the Transforming Construction Sector Deal.
The Digital Built Britain strategy expanded the remit beyond BIM to include other digital processes and technologies, including new contractual frameworks, open data standards, data analytics and big data. For example, in November 2018, the CDBB published The Gemini Principles, a framework to guide the development of the National Digital Twin - an ecosystem of connected digital twins. The National Digital Twin was first recommended in the National Infrastructure Commission's December 2017 Data for the Public Good report. Mott MacDonald CTO Mark Enzer, Head of the National Digital Twin programme, was awarded OBE in October 2020.
External links
CDBB website
Digital Twin Hub - The National Digital Twin programme online community.
References
Construction industry of the United Kingdom
Building information modeling
2017 establishments in England | Centre for Digital Built Britain | Engineering | 699 |
2,138,501 | https://en.wikipedia.org/wiki/Ultra-high-molecular-weight%20polyethylene | Ultra-high-molecular-weight polyethylene (UHMWPE, UHMW) is a subset of the thermoplastic polyethylene. Also known as high-modulus polyethylene (HMPE), it has extremely long chains, with a molecular mass usually between 3.5 and 7.5 million amu. The longer chain serves to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results in a very tough material, with the highest impact strength of any thermoplastic presently made.
UHMWPE is odorless, tasteless, and nontoxic. It embodies all the characteristics of high-density polyethylene (HDPE) with the added traits of being resistant to concentrated acids and alkalis, as well as numerous organic solvents. It is highly resistant to corrosive chemicals except oxidizing acids; has extremely low moisture absorption and a very low coefficient of friction; is self-lubricating (see boundary lubrication); and is highly resistant to abrasion, in some forms being 15 times more resistant to abrasion than carbon steel. Its coefficient of friction is significantly lower than that of nylon and acetal and is comparable to that of polytetrafluoroethylene (PTFE, Teflon), but UHMWPE has better abrasion resistance than PTFE.
Development
Polymerization of UHMWPE was commercialized in the 1950s by Ruhrchemie AG, which has changed names over the years. Today UHMWPE powder materials, which may be directly molded into a product's final shape, are produced by Ticona, Braskem, Teijin (Endumax), Celanese, and Mitsui. Processed UHMWPE is available commercially either as fibers or in consolidated form, such as sheets or rods. Because of its resistance to wear and impact, UHMWPE continues to find increasing industrial applications, including the automotive and bottling sectors. Since the 1960s, UHMWPE has also been the material of choice for total joint arthroplasty in orthopedic and spine implants.
UHMWPE fibers branded as Dyneema, commercialized in the late 1970s by the Dutch chemical company DSM, and as Spectra, commercialized by Honeywell (then AlliedSignal), are widely used in ballistic protection, defense applications, and increasingly in medical devices, sailing, hiking equipment, climbing, and many other industries.
Structure and properties
UHMWPE is a type of polyolefin. It is made up of extremely long chains of polyethylene, which all align in the same direction. It derives its strength largely from the length of each individual molecule (chain). Van der Waals forces between the molecules are relatively weak for each atom of overlap between the molecules, but because the molecules are very long, large overlaps can exist, adding up to the ability to carry larger shear forces from molecule to molecule. Each chain is attracted to the others with so many van der Waals forces that the whole of the inter-molecular strength is high. In this way, large tensile loads are not limited as much by the comparative weakness of each localized van der Waals force.
When formed into fibers, the polymer chains can attain a parallel orientation greater than 95% and a level of crystallinity from 39% to 75%. In contrast, Kevlar derives its strength from strong bonding between relatively short molecules.
The weak bonding between olefin molecules allows local thermal excitations to disrupt the crystalline order of a given chain piece-by-piece, giving it much poorer heat resistance than other high-strength fibers. Its melting point is around , and, according to DSM, it is not advisable to use UHMWPE fibres at temperatures exceeding for long periods of time. It becomes brittle at temperatures below .
The simple structure of the molecule also gives rise to surface and chemical properties that are rare in high-performance polymers. For example, the polar groups in most polymers easily bond to water. Because olefins have no such groups, UHMWPE does not absorb water readily, nor wet easily, which makes bonding it to other polymers difficult. For the same reasons, skin does not interact with it strongly, making the UHMWPE fiber surface feel slippery. In a similar manner, aromatic polymers are often susceptible to aromatic solvents due to aromatic stacking interactions, an effect aliphatic polymers like UHMWPE are immune to. Since UHMWPE does not contain chemical groups (such as esters, amides, or hydroxylic groups) that are susceptible to attack from aggressive agents, it is very resistant to water, moisture, most chemicals, UV radiation, and micro-organisms.
Under tensile load, UHMWPE will deform continually as long as the stress is present—an effect called creep.
When UHMWPE is annealed, the material is heated to between in an oven or a liquid bath of silicone oil or glycerine. The material is then cooled down to at a rate of or less. Finally, the material is wrapped in an insulating blanket for 24 hours to bring to room temperature.
Production
Ultra-high-molecular-weight polyethylene (UHMWPE) is synthesized from its monomer ethylene, which is bonded together to form the base polyethylene product. These molecules are several orders of magnitude longer than those of familiar high-density polyethylene (HDPE) due to a synthesis process based on metallocene catalysts, resulting in UHMWPE molecules typically having 100,000 to 250,000 monomer units per molecule each compared to HDPE's 700 to 1,800 monomers.
UHMWPE is processed variously by compression moulding, ram extrusion, gel spinning, and sintering. Several European companies began compression molding UHMWPE in the early 1960s. Gel-spinning arrived much later and was intended for different applications.
In gel spinning a precisely heated gel (of a low concentration of UHMWPE in an oil) is extruded through a spinneret. The extrudate is drawn through the air, the oil extracted with a solvent which does not affect the UHMWPE, and then dried removing the solvent. The end-result is a fiber with a high degree of molecular orientation, and therefore exceptional tensile strength. Gel spinning depends on isolating individual chain molecules in the solvent so that intermolecular entanglements are minimal. Entanglements make chain orientation more difficult, and lower the strength of the final product.
Applications
Fiber
Dyneema and Spectra are brands of lightweight high-strength oriented-strand gels spun through a spinneret. They have yield strengths as high as and density as low as (for Dyneema SK75). High-strength steels have comparable yield strengths, and low-carbon steels have yield strengths much lower (around ). Since steel has a specific gravity of roughly 7.8, these materials have a strength-to-weight ratios eight times that of high-strength steels. Strength-to-weight ratios for UHMWPE are about 40% higher than for aramid. The high qualities of UHMWPE filament were discovered by Albert Pennings in 1968, but commercially viable products were made available by DSM in 1990 and Southern Ropes soon after.
Derivatives of UHMWPE yarn are used in composite plates in armor, in particular, personal armor and on occasion as vehicle armor. Civil applications containing UHMWPE fibers are cut-resistant gloves, tear-resistant hosiery, bow strings, climbing equipment, automotive winching, fishing line, spear lines for spearguns, high-performance sails, suspension lines on sport parachutes and paragliders, rigging in yachting, kites, and kite lines for kites sports.
For personal armor, the fibers are, in general, aligned and bonded into sheets, which are then layered at various angles to give the resulting composite material strength in all directions. Recently developed additions to the US Military's Interceptor body armor, designed to offer arm and leg protection, are said to utilize a form of UHMWPE fabric. A multitude of UHMWPE woven fabrics are available in the market and are used as shoe liners, pantyhose, fencing clothing, stab-resistant vests, and composite liners for vehicles.
The use of UHMWPE rope for automotive winching offers several advantages over the more common steel wire rope. The key reason for changing to UHMWPE rope is improved safety. The lower mass of UHMWPE rope, coupled with significantly lower elongation at breaking, carries far less energy than steel or nylon, which leads to almost no snap-back. UHMWPE rope does not develop kinks that can cause weak spots, and any frayed areas that may develop along the surface of the rope cannot pierce the skin like broken steel wire strands can. UHMWPE rope is less dense than water, making water recoveries easier as the recovery cable is easier to locate than wire rope. The bright colours available also aid with visibility should the rope become submerged or dirty. Another advantage in automotive applications is the reduced weight of UHMWPE rope over steel cables. A typical UHMWPE rope of can weigh around , the equivalent steel wire rope would weigh around . One notable drawback of UHMWPE rope is its susceptibility to UV damage, so many users will fit winch covers in order to protect the cable when not in use. It is also vulnerable to heat damage from contact with hot components.
Spun UHMWPE fibers excel as fishing line, as they have less stretch, are more abrasion-resistant, and are thinner than the equivalent monofilament line.
In climbing, cord and webbing made of combinations of UHMWPE and nylon yarn have gained popularity for their low weight and bulk. They exhibit very low elasticity compared to their nylon counterparts, which translates to low toughness. The fiber's very high lubricity causes poor knot-holding ability, and it is mostly used in pre-sewn 'slings' (loops of webbing)—relying on knots to join sections of UHMWPE is generally not recommended, and if necessary it is recommended to use the triple fisherman's knot rather than the traditional double fisherman's knot.
Ships' hawsers and cables made from the fiber (0.97 specific gravity) float on sea water. "Spectra wires" as they are called in the towing boat community are commonly used for face wires
as a lighter alternative to steel wires.
It is used in skis and snowboards, often in combination with carbon fiber, reinforcing the fiberglass composite material, adding stiffness and improving its flex characteristics. The UHMWPE is often used as the base layer, which contacts the snow, and includes abrasives to absorb and retain wax.
It is also used in lifting applications, for manufacturing low weight, and heavy duty lifting slings. Due to its extreme abrasion resistance it is also used as an excellent corner protection for synthetic lifting slings.
High-performance lines (such as backstays) for sailing and parasailing are made of UHMWPE, due to their low stretch, high strength, and low weight. Similarly, UHMWPE is often used for winch-launching gliders from the ground, as, in comparison with steel cable, its superior abrasion resistance results in less wear when running along the ground and into the winch, increasing the time between failures. The lower weight on the mile-long cables used also results in higher winch launches.
UHMWPE was used for the long, thick space tether in the ESA/Russian Young Engineers' Satellite 2 of September, 2007.
Dyneema composite fabric (DCF) is a laminated material consisting of a grid of Dyneema threads sandwiched between two thin transparent polyester membranes. This material is very strong for its weight, and was originally developed for use in racing yacht sails under the name 'Cuben Fiber'. More recently it has found new applications, most notably in the manufacture of lightweight and ultralight camping and backpacking equipment such as tents, backpacks, and bear-proof food bags.
In archery, UHMWPE is widely used as a material for bowstrings because of its low creep and stretch compared to, for example, Dacron (PET). Besides pure UHMWPE fibers, most manufacturers use blends to further reduce the creep and stretch of the material. In these blends, the UHMWPE fibers are blended with, for example, Vectran.
In skydiving, UHMWPE is one of the most common materials used for suspension lines, largely supplanting the earlier-used Dacron, being lighter and less bulky. UHMWPE has excellent strength and wear-resistance, but is not dimensionally stable (i.e. shrinks) when exposed to heat, which leads to gradual and uneven shrinkage of different lines as they are subject to differing amounts of friction during canopy deployment, necessitating periodic line replacement. It is also almost completely inelastic, which can exacerbate the opening shock. For that reason, Dacron lines continue to be used in student and some tandem systems, where the added bulk is less of a concern than the potential for an injurious opening. In turn, in high-performance parachutes used for swooping, UHMWPE is replaced with Vectran and HMA (high-modulus aramid), which are even thinner and dimensionally stable, but exhibit greater wear and require much more frequent maintenance to prevent catastrophic failure. UHMWPE are also used for reserve parachute closing loops when used with automatic activation devices, where their extremely low coefficient of friction is critical for proper operation in the event of cutter activation.
Medical
UHMWPE has a clinical history as a biomaterial for use in hip, knee, and (since the 1980s), for spine implants. An online repository of information and review articles related to medical grade UHMWPE, known as the UHMWPE Lexicon, was started online in 2000.
Joint replacement components have historically been made from "GUR" resins. These powder materials are produced by Ticona, typically converted into semi-forms by companies such as Quadrant and Orthoplastics, and then machined into implant components and sterilized by device manufacturers.
UHMWPE was first used clinically in 1962 by Sir John Charnley and emerged as the dominant bearing material for total hip and knee replacements in the 1970s. Throughout its history, there were unsuccessful attempts to modify UHMWPE to improve its clinical performance until the development of highly cross-linked UHMWPE in the late 1990s.
One unsuccessful attempt to modify UHMWPE was by blending the powder with carbon fibers. This reinforced UHMWPE was released clinically as "Poly Two" by Zimmer in the 1970s. The carbon fibers had poor compatibility with the UHMWPE matrix and its clinical performance was inferior to virgin UHMWPE.
A second attempt to modify UHMWPE was by high-pressure recrystallization. This recrystallized UHMWPE was released clinically as "Hylamer" by DePuy in the late 1980s. When gamma irradiated in air, this material exhibited susceptibility to oxidation, resulting in inferior clinical performance relative to virgin UHMWPE. Today, the poor clinical history of Hylamer is largely attributed to its sterilization method, and there has been a resurgence of interest in studying this material (at least among certain research circles). Hylamer fell out of favor in the United States in the late 1990s with the development of highly cross-linked UHMWPE materials, however negative clinical reports from Europe about Hylamer continue to surface in the literature.
Highly cross-linked UHMWPE materials were clinically introduced in 1998 and have rapidly become the standard of care for total hip replacements, at least in the United States. These new materials are cross-linked with gamma or electron beam radiation (50–105 kGy) and then thermally processed to improve their oxidation resistance. Five-year clinical data, from several centers, are now available demonstrating their superiority relative to conventional UHMWPE for total hip replacement (see arthroplasty). Clinical studies are still underway to investigate the performance of highly cross-linked UHMWPE for knee replacement.
In 2007, manufacturers started incorporating anti-oxidants into UHMWPE for hip and knee arthroplasty bearing surfaces. Vitamin E (a-tocopherol) is the most common anti-oxidant used in radiation-cross-linked UHMWPE for medical applications. The anti-oxidant helps quench free radicals that are introduced during the irradiation process, imparting improved oxidation resistance to the UHMWPE without the need for thermal treatment. Several companies have been selling antioxidant-stabilized joint replacement technologies since 2007, using both synthetic vitamin E as well as hindered phenol-based antioxidants.
Another important medical advancement for UHMWPE in the past decade has been the increase in use of fibers for sutures. Medical-grade fibers for surgical applications are produced by DSM under the "Dyneema Purity" trade name.
Manufacturing
UHMWPE is used in the manufacture of PVC (vinyl) windows and doors, as it can endure the heat required to soften the PVC-based materials and is used as a form/chamber filler for the various PVC shape profiles in order for those materials to be 'bent' or shaped around a template.
UHMWPE is also used in the manufacture of hydraulic seals and bearings. It is best suited for medium mechanical duties in water, oil hydraulics, pneumatics, and unlubricated applications. It has a good abrasion resistance but is better suited to soft mating surfaces.
Wire and cable
Fluoropolymer / HMWPE insulation cathodic protection cable is typically made with dual insulation. It features a primary layer of a fluoropolymer such as ethylene-chlorotrifluoroethylene (ECTFE) which is chemically resistant to chlorine, sulfuric acid, and hydrochloric acid. Following the primary layer is an HMWPE insulation layer, which provides pliable strength and allows considerable abuse during installation. The HMWPE jacketing provides mechanical protection as well.
Marine infrastructure
UHMWPE is used in marine structures for the mooring of ships and floating structures in general. The UHMWPE forms the contact surface between the floating structure and the fixed one. Timber was and is used for this application also. UHMWPE is chosen as facing of fender systems for berthing structures because of the following characteristics:
Wear resistance: best among plastics, better than steel
Impact resistance: best among plastics, similar to steel
Low friction (wet and dry conditions): self-lubricating material
See also
Low-density polyethylene (LDPE)
Medium-density polyethylene (MDPE)
Twaron
IPX Ultra-high-molecular-weight polyethylene
References
Further reading
Southern et al., The Properties of Polyethylene Crystallized Under the Orientation and Pressure Effects of a Pressure Capillary Viscometer, Journal of Applied Polymer Science vol. 14, pp. 2305–2317 (1970).
Kanamoto, On Ultra-High Tensile by Drawing Single Crystal Mats of High Molecular Weight Polyethylene, Polymer Journal vol. 15, No. 4, pp. 327–329 (1983).
External links
US Patent 5342567 Process for producing high tenacity and high modulus polyethylene fibers, issued 1994-08-30
Polymer Gel Spinning Machine Christine A. Odero, MIT, 1994
Patent application 20070148452 High strength polyethylene fiber, 2007-06-28
Analytical techniques to characterize radiation effects on UHMWPE
Next generation orthopedic implants using UHMWPE
Highly crosslinked VE-UHMWPE for hip and knee replacements
UHMWPE Characteristics, Processing Methods, Applications
Polyethylene UHMWPE HDPE LDPE LLDPE – What are the differences?
HMPE Fibre – How is it made?
Brand name materials
Body armor
Polyolefins
Plastics
Synthetic fibers | Ultra-high-molecular-weight polyethylene | Physics,Chemistry | 4,297 |
49,335,555 | https://en.wikipedia.org/wiki/Cheshire%20Brine%20Subsidence%20Compensation%20Board | The Cheshire Brine Subsidence Compensation Board was created by the Cheshire Brine Pumping (Compensation for Subsidence) Act 1952 (15 & 16 Geo. 6 & 1 Eliz. 2. c. xlii).
It pays compensation caused by any subsidence damage in Cheshire attributable to the practice of brine pumping.
See also
Salt in Cheshire
References
External links
Official website
Salt production
Organisations based in Cheshire | Cheshire Brine Subsidence Compensation Board | Chemistry | 88 |
23,374,329 | https://en.wikipedia.org/wiki/ChemBioChem | ChemBioChem is a peer-reviewed scientific journal covering chemical biology, synthetic biology, and bio-nanotechnology and published by Wiley-VCH on behalf of Chemistry Europe. The journal publishes communications, full papers, reviews, minireviews, highlights, concepts, book reviews, and conference reports. Viewpoints, correspondence, essays, web sites, and databases are also occasionally featured. It is abstracted and indexed in major databases and has been online-only since 2016.
According to the Journal Citation Reports, the journal has a 2021 impact factor of 3.461.
References
External links
Chemistry Europe academic journals
Academic journals established in 2000
Biochemistry journals
English-language journals
Online-only journals
Journals published between 13 and 25 times per year
Wiley-VCH academic journals | ChemBioChem | Chemistry | 158 |
5,609,640 | https://en.wikipedia.org/wiki/Grammatical%20evolution | Grammatical evolution (GE) is a genetic programming (GP) technique (or approach) from evolutionary computation pioneered by Conor Ryan, JJ Collins and Michael O'Neill in 1998 at the BDS Group in the University of Limerick.
As in any other GP approach, the objective is to find an executable program, program fragment, or function, which will achieve a good fitness value for a given objective function. In most published work on GP, a LISP-style tree-structured expression is directly manipulated, whereas GE applies genetic operators to an integer string, subsequently mapped to a program (or similar) through the use of a grammar, which is typically expressed in Backus–Naur form. One of the benefits of GE is that this mapping simplifies the application of search to different programming languages and other structures.
Problem addressed
In type-free, conventional Koza-style GP, the function set must meet the requirement of closure: all functions must be capable of accepting as their arguments the output of all other functions in the function set. Usually, this is implemented by dealing with a single data-type such as double-precision floating point. While modern Genetic Programming frameworks support typing, such type-systems have limitations that Grammatical Evolution does not suffer from.
GE's solution
GE offers a solution to the single-type limitation by evolving solutions according to a user-specified grammar (usually a grammar in Backus-Naur form). Therefore the search space can be restricted, and domain knowledge of the problem can be incorporated. The inspiration for this approach comes from a desire to separate the "genotype" from the "phenotype": in GP, the objects the search algorithm operates on and what the fitness evaluation function interprets are one and the same. In contrast, GE's "genotypes" are ordered lists of integers which code for selecting rules from the provided context-free grammar. The phenotype, however, is the same as in Koza-style GP: a tree-like structure that is evaluated recursively. This model is more in line with how genetics work in nature, where there is a separation between an organism's genotype and the final expression of phenotype in proteins, etc.
Separating genotype and phenotype allows a modular approach. In particular, the search portion of the GE paradigm needn't be carried out by any one particular algorithm or method. Observe that the objects GE performs search on are the same as those used in genetic algorithms. This means, in principle, that any existing genetic algorithm package, such as the popular GAlib, can be used to carry out the search, and a developer implementing a GE system need only worry about carrying out the mapping from list of integers to program tree. It is also in principle possible to perform the search using some other method, such as particle swarm optimization (see the remark below); the modular nature of GE creates many opportunities for hybrids as the problem of interest to be solved dictates.
Brabazon and O'Neill have successfully applied GE to predicting corporate bankruptcy, forecasting stock indices, bond credit ratings, and other financial applications. GE has also been used with a classic predator-prey model to explore the impact of parameters such as predator efficiency, niche number, and random mutations on ecological stability.
It is possible to structure a GE grammar that for a given function/terminal set is equivalent to genetic programming.
Criticism
Despite its successes, GE has been the subject of some criticism. One issue is that as a result of its mapping operation, GE's genetic operators do not achieve high locality which is a highly regarded property of genetic operators in evolutionary algorithms.
Variants
Although GE was originally described in terms of using an Evolutionary Algorithm, specifically, a Genetic Algorithm, other variants exist. For example, GE researchers have experimented with using particle swarm optimization to carry out the searching instead of genetic algorithms with results comparable to that of normal GE; this is referred to as a "grammatical swarm"; using only the basic PSO model it has been found that PSO is probably equally capable of carrying out the search process in GE as simple genetic algorithms are. (Although PSO is normally a floating-point search paradigm, it can be discretized, e.g., by simply rounding each vector to the nearest integer, for use with GE.)
Yet another possible variation that has been experimented with in the literature is attempting to encode semantic information in the grammar in order to further bias the search process. Other work showed that, with biased grammars that leverage domain knowledge, even random search can be used to drive GE.
Related Work
GE was originally a combination of the linear representation as used by the Genetic Algorithm for Developing Software (GADS) and Backus Naur Form grammars, which were originally used in tree-based GP by Wong and Leung in 1995 and Whigham in 1996. Other related work noted in the original GE paper was that of Frederic Gruau, who used a conceptually similar "embryonic" approach, as well as that of Keller and Banzhaf, which similarly used linear genomes.
Implementations
There are several implementations of GE. These include the following.
See also
Genetic programming
Java Grammatical Evolution
Cartesian genetic programming
Gene expression programming
Linear genetic programming
Multi expression programming
Notes
Resources
Grammatical Evolution Tutorial.
Grammatical Evolution in Java .
jGE - Java Grammatical Evolution.
The Biocomputing and Developmental Systems (BDS) Group at the University of Limerick.
Michael O'Neill's Grammatical Evolution Page, including a bibliography.
DRP, Directed Ruby Programming, is an experimental system designed to let users create hybrid GE/GP systems. It is implemented in pure Ruby.
GERET, Grammatical Evolution Ruby Exploratory Toolkit.
gramEvol, Grammatical Evolution for R. | Grammatical evolution | Biology | 1,176 |
9,598 | https://en.wikipedia.org/wiki/Electronvolt | In physics, an electronvolt (symbol eV), also written electron-volt and electron volt, is the measure of an amount of kinetic energy gained by a single electron accelerating through an electric potential difference of one volt in vacuum. When used as a unit of energy, the numerical value of 1 eV in joules (symbol J) is equal to the numerical value of the charge of an electron in coulombs (symbol C). Under the 2019 revision of the SI, this sets 1 eV equal to the exact value
Historically, the electronvolt was devised as a standard unit of measure through its usefulness in electrostatic particle accelerator sciences, because a particle with electric charge q gains an energy after passing through a voltage of V.
Definition and use
An electronvolt is the amount of energy gained or lost by a single electron when it moves through an electric potential difference of one volt. Hence, it has a value of one volt, which is , multiplied by the elementary charge Therefore, one electronvolt is equal to
The electronvolt (eV) is a unit of energy, but is not an SI unit. It is a commonly used unit of energy within physics, widely used in solid state, atomic, nuclear and particle physics, and high-energy astrophysics. It is commonly used with SI prefixes milli- (10−3), kilo- (103), mega- (106), giga- (109), tera- (1012), peta- (1015) or exa- (1018), the respective symbols being meV, keV, MeV, GeV, TeV, PeV and EeV. The SI unit of energy is the joule (J).
In some older documents, and in the name Bevatron, the symbol BeV is used, where the B stands for billion. The symbol BeV is therefore equivalent to GeV, though neither is an SI unit.
Relation to other physical properties and units
In the fields of physics in which the electronvolt is used, other quantities are typically measured using units derived from the electronvolt as a product with fundamental constants of importance in the theory are often used.
Mass
By mass–energy equivalence, the electronvolt corresponds to a unit of mass. It is common in particle physics, where units of mass and energy are often interchanged, to express mass in units of eV/c2, where c is the speed of light in vacuum (from ). It is common to informally express mass in terms of eV as a unit of mass, effectively using a system of natural units with c set to 1. The kilogram equivalent of is:
For example, an electron and a positron, each with a mass of , can annihilate to yield of energy. A proton has a mass of . In general, the masses of all hadrons are of the order of , which makes the GeV/c2 a convenient unit of mass for particle physics:
The atomic mass constant (mu), one twelfth of the mass a carbon-12 atom, is close to the mass of a proton. To convert to electronvolt mass-equivalent, use the formula:
Momentum
By dividing a particle's kinetic energy in electronvolts by the fundamental constant c (the speed of light), one can describe the particle's momentum in units of eV/c. In natural units in which the fundamental velocity constant c is numerically 1, the c may informally be omitted to express momentum using the unit electronvolt.
The energy–momentum relation
in natural units (with )
is a Pythagorean equation. When a relatively high energy is applied to a particle with relatively low rest mass, it can be approximated as in high-energy physics such that an applied energy with expressed in the unit eV conveniently results in a numerically approximately equivalent change of momentum when expressed with the unit eV/c.
The dimension of momentum is . The dimension of energy is . Dividing a unit of energy (such as eV) by a fundamental constant (such as the speed of light) that has the dimension of velocity () facilitates the required conversion for using a unit of energy to quantify momentum.
For example, if the momentum p of an electron is , then the conversion to MKS system of units can be achieved by:
Distance
In particle physics, a system of natural units in which the speed of light in vacuum c and the reduced Planck constant ħ are dimensionless and equal to unity is widely used: . In these units, both distances and times are expressed in inverse energy units (while energy and mass are expressed in the same units, see mass–energy equivalence). In particular, particle scattering lengths are often presented using a unit of inverse particle mass.
Outside this system of units, the conversion factors between electronvolt, second, and nanometer are the following:
The above relations also allow expressing the mean lifetime τ of an unstable particle (in seconds) in terms of its decay width Γ (in eV) via . For example, the meson has a lifetime of 1.530(9) picoseconds, mean decay length is , or a decay width of .
Conversely, the tiny meson mass differences responsible for meson oscillations are often expressed in the more convenient inverse picoseconds.
Energy in electronvolts is sometimes expressed through the wavelength of light with photons of the same energy:
Temperature
In certain fields, such as plasma physics, it is convenient to use the electronvolt to express temperature. The electronvolt is divided by the Boltzmann constant to convert to the Kelvin scale:
where kB is the Boltzmann constant.
The kB is assumed when using the electronvolt to express temperature, for example, a typical magnetic confinement fusion plasma is (kiloelectronvolt), which is equal to 174 MK (megakelvin).
As an approximation: kBT is about (≈ ) at a temperature of .
Wavelength
The energy E, frequency ν, and wavelength λ of a photon are related by
where h is the Planck constant, c is the speed of light. This reduces to
A photon with a wavelength of (green light) would have an energy of approximately . Similarly, would correspond to an infrared photon of wavelength or frequency .
Scattering experiments
In a low-energy nuclear scattering experiment, it is conventional to refer to the nuclear recoil energy in units of eVr, keVr, etc. This distinguishes the nuclear recoil energy from the "electron equivalent" recoil energy (eVee, keVee, etc.) measured by scintillation light. For example, the yield of a phototube is measured in phe/keVee (photoelectrons per keV electron-equivalent energy). The relationship between eV, eVr, and eVee depends on the medium the scattering takes place in, and must be established empirically for each material.
Energy comparisons
Molar energy
One mole of particles given 1 eV of energy each has approximately 96.5 kJ of energy – this corresponds to the Faraday constant (F ≈ ), where the energy in joules of n moles of particles each with energy E eV is equal to E·F·n.
See also
Orders of magnitude (energy)
References
External links
Fundamental Physical Constants from NIST
Particle physics
Units of chemical measurement
Units of energy
Voltage
Electron | Electronvolt | Physics,Chemistry,Mathematics | 1,515 |
1,701,055 | https://en.wikipedia.org/wiki/Sol%E2%80%93gel%20process | In materials science, the sol–gel process is a method for producing solid materials from small molecules. The method is used for the fabrication of metal oxides, especially the oxides of silicon (Si) and titanium (Ti). The process involves conversion of monomers in solution into a colloidal solution (sol) that acts as the precursor for an integrated network (or gel) of either discrete particles or network polymers. Typical precursors are metal alkoxides. Sol–gel process is used to produce ceramic nanoparticles.
Stages
In this chemical procedure, a "sol" (a colloidal solution) is formed that then gradually evolves towards the formation of a gel-like diphasic system containing both a liquid phase and solid phase whose morphologies range from discrete particles to continuous polymer networks. In the case of the colloid, the volume fraction of particles (or particle density) may be so low that a significant amount of fluid may need to be removed initially for the gel-like properties to be recognized. This can be accomplished in any number of ways. The simplest method is to allow time for sedimentation to occur, and then pour off the remaining liquid. Centrifugation can also be used to accelerate the process of phase separation.
Removal of the remaining liquid (solvent) phase requires a drying process, which is typically accompanied by a significant amount of shrinkage and densification. The rate at which the solvent can be removed is ultimately determined by the distribution of porosity in the gel. The ultimate microstructure of the final component will clearly be strongly influenced by changes imposed upon the structural template during this phase of processing.
Afterwards, a thermal treatment, or firing process, is often necessary in order to favor further polycondensation and enhance mechanical properties and structural stability via final sintering, densification, and grain growth. One of the distinct advantages of using this methodology as opposed to the more traditional processing techniques is that densification is often achieved at a much lower temperature.
The precursor sol can be either deposited on a substrate to form a film (e.g., by dip-coating or spin coating), cast into a suitable container with the desired shape (e.g., to obtain monolithic ceramics, glasses, fibers, membranes, aerogels), or used to synthesize powders (e.g., microspheres, nanospheres). The sol–gel approach is a cheap and low-temperature technique that allows the fine control of the product's chemical composition. Even small quantities of dopants, such as organic dyes and rare-earth elements, can be introduced in the sol and end up uniformly dispersed in the final product. It can be used in ceramics processing and manufacturing as an investment casting material, or as a means of producing very thin films of metal oxides for various purposes. Sol–gel derived materials have diverse applications in optics, electronics, energy, space, (bio)sensors, medicine (e.g., controlled drug release), reactive material, and separation (e.g., chromatography) technology.
The interest in sol–gel processing can be traced back in the mid-1800s with the observation that the hydrolysis of tetraethyl orthosilicate (TEOS) under acidic conditions led to the formation of SiO2 in the form of fibers and monoliths. Sol–gel research grew to be so important that in the 1990s more than 35,000 papers were published worldwide on the process.
Particles and polymers
The sol–gel process is a wet-chemical technique used for the fabrication of both glassy and ceramic materials. In this process, the sol (or solution) evolves gradually towards the formation of a gel-like network containing both a liquid phase and a solid phase. Typical precursors are metal alkoxides and metal chlorides, which undergo hydrolysis and polycondensation reactions to form a colloid. The basic structure or morphology of the solid phase can range anywhere from discrete colloidal particles to continuous chain-like polymer networks.
The term colloid is used primarily to describe a broad range of solid-liquid (and/or liquid-liquid) mixtures, all of which contain distinct solid (and/or liquid) particles which are dispersed to various degrees in a liquid medium. The term is specific to the size of the individual particles, which are larger than atomic dimensions but small enough to exhibit Brownian motion. If the particles are large enough, then their dynamic behavior in any given period of time in suspension would be governed by forces of gravity and sedimentation. But if they are small enough to be colloids, then their irregular motion in suspension can be attributed to the collective bombardment of a myriad of thermally agitated molecules in the liquid suspending medium, as described originally by Albert Einstein in his dissertation. Einstein concluded that this erratic behavior could adequately be described using the theory of Brownian motion, with sedimentation being a possible long-term result. This critical size range (or particle diameter) typically ranges from tens of angstroms (10−10 m) to a few micrometres (10−6 m).
Under certain chemical conditions (typically in base-catalyzed sols), the particles may grow to sufficient size to become colloids, which are affected both by sedimentation and forces of gravity. Stabilized suspensions of such sub-micrometre spherical particles may eventually result in their self-assembly—yielding highly ordered microstructures reminiscent of the prototype colloidal crystal: precious opal.
Under certain chemical conditions (typically in acid-catalyzed sols), the interparticle forces have sufficient strength to cause considerable aggregation and/or flocculation prior to their growth. The formation of a more open continuous network of low density polymers exhibits certain advantages with regard to physical properties in the formation of high performance glass and glass/ceramic components in 2 and 3 dimensions.
In either case (discrete particles or continuous polymer network) the sol evolves then towards the formation of an inorganic network containing a liquid phase (gel). Formation of a metal oxide involves connecting the metal centers with oxo (M-O-M) or hydroxo (M-OH-M) bridges, therefore generating metal-oxo or metal-hydroxo polymers in solution.
In both cases (discrete particles or continuous polymer network), the drying process serves to remove the liquid phase from the gel, yielding a micro-porous amorphous glass or micro-crystalline ceramic. Subsequent thermal treatment (firing) may be performed in order to favor further polycondensation and enhance mechanical properties.
With the viscosity of a sol adjusted into a proper range, both optical quality glass fiber and refractory ceramic fiber can be drawn which are used for fiber optic sensors and thermal insulation, respectively. In addition, uniform ceramic powders of a wide range of chemical composition can be formed by precipitation.
Polymerization
The Stöber process is a well-studied example of polymerization of an alkoxide, specifically TEOS. The chemical formula for TEOS is given by Si(OC2H5)4, or Si(OR)4, where the alkyl group R = C2H5. Alkoxides are ideal chemical precursors for sol–gel synthesis because they react readily with water. The reaction is called hydrolysis, because a hydroxyl ion becomes attached to the silicon atom as follows:
Si(OR)4 + H2O → HO−Si(OR)3 + R−OH
Depending on the amount of water and catalyst present, hydrolysis may proceed to completion to silica:
Si(OR)4 + 2 H2O → SiO2 + 4 R−OH
Complete hydrolysis often requires an excess of water and/or the use of a hydrolysis catalyst such as acetic acid or hydrochloric acid. Intermediate species including [(OR)2−Si−(OH)2] or [(OR)3−Si−(OH)] may result as products of partial hydrolysis reactions. Early intermediates result from two partially hydrolyzed monomers linked with a siloxane [Si−O−Si] bond:
(OR)3−Si−OH + HO−Si−(OR)3 → [(OR)3Si−O−Si(OR)3] + H−O−H
or
(OR)3−Si−OR + HO−Si−(OR)3 → [(OR)3Si−O−Si(OR)3] + R−OH
Thus, polymerization is associated with the formation of a 1-, 2-, or 3-dimensional network of siloxane [Si−O−Si] bonds accompanied by the production of H−O−H and R−O−H species.
By definition, condensation liberates a small molecule, such as water or alcohol. This type of reaction can continue to build larger and larger silicon-containing molecules by the process of polymerization. Thus, a polymer is a huge molecule (or macromolecule) formed from hundreds or thousands of units called monomers. The number of bonds that a monomer can form is called its functionality. Polymerization of silicon alkoxide, for instance, can lead to complex branching of the polymer, because a fully hydrolyzed monomer Si(OH)4 is tetrafunctional (can branch or bond in 4 different directions). Alternatively, under certain conditions (e.g., low water concentration) fewer than 4 of the OR or OH groups (ligands) will be capable of condensation, so relatively little branching will occur. The mechanisms of hydrolysis and condensation, and the factors that bias the structure toward linear or branched structures are the most critical issues of sol–gel science and technology. This reaction is favored in both basic and acidic conditions.
Sono-Ormosil
Sonication is an efficient tool for the synthesis of polymers. The cavitational shear forces, which stretch out and break the chain in a non-random process, result in a lowering of the molecular weight and poly-dispersity. Furthermore, multi-phase systems are very efficient dispersed and emulsified, so that very fine mixtures are provided. This means that ultrasound increases the rate of polymerisation over conventional stirring and results in higher molecular weights with lower polydispersities. Ormosils (organically modified silicate) are obtained when silane is added to gel-derived silica during sol–gel process. The product is a molecular-scale composite with improved mechanical properties. Sono-Ormosils are characterized by a higher density than classic gels as well as an improved thermal stability. An explanation therefore might be the increased degree of polymerization.
Pechini process
For single cation systems like SiO2 and TiO2, hydrolysis and condensation processes naturally give rise to homogenous compositions. For systems involving multiple cations, such as strontium titanate, SrTiO3 and other perovskite systems, the concept of steric immobilisation becomes relevant. To avoid the formation of multiple phases of binary oxides as the result of differing hydrolysis and condensation rates, the entrapment of cations in a polymer network is an effective approach, generally termed the Pechini process. In this process, a chelating agent is used, most often citric acid, to surround aqueous cations and sterically entrap them. Subsequently, a polymer network is formed to immobilize the chelated cations in a gel or resin. This is most often achieved by poly-esterification using ethylene glycol. The resulting polymer is then combusted under oxidising conditions to remove organic content and yield a product oxide with homogeneously dispersed cations.
Nanomaterials, aerogels, xerogels
If the liquid in a wet gel is removed under a supercritical condition, a highly porous and extremely low density material called aerogel is obtained. Drying the gel by means of low temperature treatments (25–100 °C), it is possible to obtain porous solid matrices called xerogels. In addition, a sol–gel process was developed in the 1950s for the production of radioactive powders of UO2 and ThO2 for nuclear fuels, without generation of large quantities of dust.
Differential stresses that develop as a result of non-uniform drying shrinkage are directly related to the rate at which the solvent can be removed, and thus highly dependent upon the distribution of porosity. Such stresses have been associated with a plastic-to-brittle transition in consolidated bodies, and can yield to crack propagation in the unfired body if not relieved.
In addition, any fluctuations in packing density in the compact as it is prepared for the kiln are often amplified during the sintering process, yielding heterogeneous densification.
Some pores and other structural defects associated with density variations have been shown to play a detrimental role in the sintering process by growing and thus limiting end-point densities. Differential stresses arising from heterogeneous densification have also been shown to result in the propagation of internal cracks, thus becoming the strength-controlling flaws.
It would therefore appear desirable to process a material in such a way that it is physically uniform with regard to the distribution of components and porosity, rather than using particle size distributions which will maximize the green density. The containment of a uniformly dispersed assembly of strongly interacting particles in suspension requires total control over particle-particle interactions. Monodisperse colloids provide this potential.
Monodisperse powders of colloidal silica, for example, may therefore be stabilized sufficiently to ensure a high degree of order in the colloidal crystal or polycrystalline colloidal solid which results from aggregation. The degree of order appears to be limited by the time and space allowed for longer-range correlations to be established. Such defective polycrystalline structures would appear to be the basic elements of nanoscale materials science, and, therefore, provide the first step in developing a more rigorous understanding of the mechanisms involved in microstructural evolution in inorganic systems such as sintered ceramic nanomaterials.
Ultra-fine and uniform ceramic powders can be formed by precipitation. These powders of single and multiple component compositions can be produced at a nanoscale particle size for dental, biomedical, agrochemical, or catalytic applications. Powder abrasives, used in a variety of finishing operations, are made using a sol–gel type process. One of the more important applications of sol–gel processing is to carry out zeolite synthesis. Other elements (metals, metal oxides) can be easily incorporated into the final product and the silicate sol formed by this method is very stable. Semi-stable metal complexes can be used to produce sub-2 nm oxide particles without thermal treatment. During base-catalyzed synthesis, hydroxo (M-OH) bonds may be avoided in favor of oxo (M-O-M) using a ligand which is strong enough to prevent reaction in the hydroxo regime but weak enough to allow reaction in the oxo regime (see Pourbaix diagram).
Applications
The applications for sol gel-derived products are numerous. For example, scientists have used it to produce the world's lightest materials and also some of its toughest ceramics.
Protective coatings
One of the largest application areas is thin films, which can be produced on a piece of substrate by spin coating or dip-coating. Protective and decorative coatings, and electro-optic components can be applied to glass, metal and other types of substrates with these methods. Cast into a mold, and with further drying and heat-treatment, dense ceramic or glass articles with novel properties can be formed that cannot be created by any other method. Other coating methods include spraying, electrophoresis, inkjet printing, or roll coating.
Thin films and fibers
With the viscosity of a sol adjusted into a proper range, both optical and refractory ceramic fibers can be drawn which are used for fiber optic sensors and thermal insulation, respectively. Thus, many ceramic materials, both glassy and crystalline, have found use in various forms from bulk solid-state components to high surface area forms such as thin films, coatings and fibers. Also, thin films have found their application in the electronic field and can be used as sensitive components of a resistive gas sensors.
Controlled release
Sol-gel technology has been applied for controlled release of fragrances and drugs.
Opto-mechanical
Macroscopic optical elements and active optical components as well as large area hot mirrors, cold mirrors, lenses, and beam splitters can be made by the sol–gel route. In the processing of high performance ceramic nanomaterials with superior opto-mechanical properties under adverse conditions, the size of the crystalline grains is determined largely by the size of the crystalline particles present in the raw material during the synthesis or formation of the object. Thus a reduction of the original particle size well below the wavelength of visible light (~500 nm) eliminates much of the light scattering, resulting in a translucent or even transparent material.
Furthermore, microscopic pores in sintered ceramic nanomaterials, mainly trapped at the junctions of microcrystalline grains, cause light to scatter and prevented true transparency. The total volume fraction of these nanoscale pores (both intergranular and intragranular porosity) must be less than 1% for high-quality optical transmission, i.e. the density has to be 99.99% of the theoretical crystalline density.
See also
Coacervate, small spheroidal droplet of colloidal particles in suspension
Freeze-casting
Freeze gelation
Mechanics of gelation
Random graph theory of gelation
Liquid–liquid extraction
References
Further reading
Colloidal Dispersions, Russel, W. B., et al., Eds., Cambridge University Press (1989)
Glasses and the Vitreous State, Zarzycki. J., Cambridge University Press, 1991
The Sol to Gel Transition. Plinio Innocenzi. Springer Briefs in Materials. Springer. 2016.
External links
International Sol–Gel Society
The Sol–Gel Gateway
Ceramic engineering
Dosage forms
Gels
Glass chemistry
Glass coating and surface modification
Industrial processes
Thin film deposition
Transparent materials | Sol–gel process | Physics,Chemistry,Materials_science,Mathematics,Engineering | 3,800 |
23,717,469 | https://en.wikipedia.org/wiki/C10H10O2 | {{DISPLAYTITLE:C10H10O2}}
The molecular formula C10H10O2 (molar mass : 162.18 g/mol) may refer to:
Benzoylacetone
Isosafrole, 3,4-methylenedioxyphenyl-1-propene
4-Methoxycinnamaldehyde
Methyl cinnamate
Safrole, 3,4-methylenedioxyphenyl-2-propene
4,5-Dihydro-1-benzoxepin-3(2H)-one, a watermelon flavorant | C10H10O2 | Chemistry | 130 |
320,033 | https://en.wikipedia.org/wiki/Habitat%20conservation | Habitat conservation is a management practice that seeks to conserve, protect and restore habitats and prevent species extinction, fragmentation or reduction in range. It is a priority of many groups that cannot be easily characterized in terms of any one ideology.
History of the conservation movement
For much of human history, nature was seen as a resource that could be controlled by the government and used for personal and economic gain. The idea was that plants only existed to feed animals and animals only existed to feed humans. The value of land was limited only to the resources it provided such as fertile soil, timber, and minerals.
Throughout the 18th and 19th centuries, social views started to change and conservation principles were first practically applied to the forests of British India. The conservation ethic that began to evolve included three core principles: 1) human activities damage the environment, 2) there was a civic duty to maintain the environment for future generations, and 3) scientific, empirically-based methods should be applied to ensure this duty was carried out. Sir James Ranald Martin was prominent in promoting this ideology, publishing numerous medico-topographical reports that demonstrated the damage from large-scale deforestation and desiccation, and lobbying extensively for the institutionalization of forest conservation activities in British India through the establishment of Forest Departments.
The Madras Board of Revenue started local conservation efforts in 1842, headed by Alexander Gibson, a professional botanist who systematically adopted a forest conservation program based on scientific principles. This was the first case of state conservation management of forests in the world. Governor-General Lord Dalhousie introduced the first permanent and large-scale forest conservation program in 1855, a model that soon spread to other colonies, as well to the United States, where Yellowstone National Park was opened in 1872 as the world's first national park.
Rather than focusing on the economic or material benefits from nature, humans began to appreciate the value of nature itself and the need to protect it. By the mid-20th century, countries such as the United States, Canada, and Britain instigated laws and legislation in order to ensure that the most fragile and beautiful environments would be protected for posterity.
Today, with the help of NGO's and governments worldwide, a strong movement is mobilizing with the goal of protecting habitats and preserving biodiversity on a global scale. The commitments and actions of small volunteer associations in villages and towns, that endeavour to emulate the work of well known conservation organisations, are paramount in ensuring generations that follow understand the importance of natural resource conservation.
Values of natural habitat
Natural habitats can provide Ecosystem services to humans, which are "any positive benefit that wildlife or ecosystems provide to people." The natural environment is a source for a wide range of resources that can be exploited for economic profit, for example timber is harvested from forests and clean water is obtained from natural streams. However, land development from anthropogenic economic growth often causes a decline in the ecological integrity of nearby natural habitat. For instance, this was an issue in the northern Rocky Mountains of the US.
However, there is also the economic value in conserving natural habitats. Financial profit can be made from tourist revenue, for example in the tropics where species diversity is high, or in recreational sports which take place in natural environments such as hiking and mountain biking. The cost of repairing damaged ecosystems is considered to be much higher than the cost of conserving natural ecosystems.
Measuring the worth of conserving different habitat areas is often criticized as being too utilitarian from a philosophical point of view.
Biodiversity
Habitat conservation is important in maintaining biodiversity, which refers to the variability in populations, organisms, and gene pools, as well as habitats and ecosystems. Biodiversity is also an essential part of global food security. There is evidence to support a trend of accelerating erosion of the genetic resources of agricultural plants and animals. An increase in genetic similarity of agricultural plants and animals means an increased risk of food loss from major epidemics. Wild species of agricultural plants have been found to be more resistant to disease, for example the wild corn species Teosinte is resistant to 4 corn diseases that affect human grown crops. A combination of seed banking and habitat conservation has been proposed to maintain plant diversity for food security purposes. It has been shown that focusing conversation efforts on ecosystems "within multiple trophic levels" can lead to a better functioning ecosystem with more biomass.
Classifying environmental values
Pearce and Moran outlined the following method for classifying environmental uses:
Direct extractive uses: e.g. timber from forests, food from plants and animals
Indirect uses: e.g. ecosystem services like flood control, pest control, erosion protection
Optional uses: future possibilities e.g. unknown but potential use of plants in chemistry/medicine
Non-use values:
Bequest value (benefit of an individual who knows that others may benefit from it in future)
Passive use value (sympathy for natural environment, enjoyment of the mere existence of a particular species)
Impacts
Natural causes
Habitat loss and destruction can occur both naturally and through anthropogenic causes. Events leading to natural habitat loss include climate change, catastrophic events such as volcanic explosions and through the interactions of invasive and non-invasive species. Natural climate change, events have previously been the cause of many widespread and large scale losses in habitat. For example, some of the mass extinction events generally referred to as the "Big Five" have coincided with large scale such as the Earth entering an ice age, or alternate warming events. Other events in the big five also have their roots in natural causes, such as volcanic explosions and meteor collisions. The Chicxulub impact is one such example, which has previously caused widespread losses in habitat as the Earth either received less sunlight or grew colder, causing certain fauna and flora to flourish whilst others perished. Previously known warm areas in the tropics, the most sensitive habitats on Earth, grew colder, and areas such as Australia developed radically different flora and fauna to those seen today. The big five mass extinction events have also been linked to sea level changes, indicating that large scale marine species loss was strongly influenced by loss in marine habitats, particularly shelf habitats. Methane-driven oceanic eruptions have also been shown to have caused smaller mass extinction events.
Human impacts
Humans have been the cause of many species’ extinction. Due to humans’ changing and modifying their environment, the habitat of other species often become altered or destroyed as a result of human actions. The altering of habitats will cause habitat fragmentation, reducing the species' habitat and decreasing their dispersal range. This increases species isolation which then causes their population to decline. Even before the modern industrial era, humans were having widespread, and major effects on the environment. A good example of this is found in Aboriginal Australians and Australian megafauna. Aboriginal hunting practices, which included burning large sections of forest at a time, eventually altered and changed Australia's vegetation so much that many herbivorous megafauna species were left with no habitat and were driven into extinction. Once herbivorous megafauna species became extinct, carnivorous megafauna species soon followed.
In the recent past, humans have been responsible for causing more extinctions within a given period of time than ever before. Deforestation, pollution, anthropogenic climate change and human settlements have all been driving forces in altering or destroying habitats. The destruction of ecosystems such as rainforests has resulted in countless habitats being destroyed. These biodiversity hotspots are home to millions of habitat specialists, which do not exist beyond a tiny area. Once their habitat is destroyed, they cease to exist. This destruction has a follow-on effect, as species which coexist or depend upon the existence of other species also become extinct, eventually resulting in the collapse of an entire ecosystem. These time-delayed extinctions are referred to as the extinction debt, which is the result of destroying and fragmenting habitats.
As a result of anthropogenic modification of the environment, the extinction rate has climbed to the point where the Earth is now within a sixth mass extinction event, as commonly agreed by biologists. This has been particularly evident, for example, in the rapid decline in the number of amphibian species worldwide.
Approaches and methods of habitat conservation
Adaptive management addresses the challenge of scientific uncertainty in habitat conservation plans by systematically gathering and applying reliable information to enhance conservation strategies over time. This approach allows for adjustments in management practices based on new insights, making conservation efforts more effective. Determining the size, type and location of habitat to conserve is a complex area of conservation biology. Although difficult to measure and predict, the conservation value of a habitat is often a reflection of the quality (e.g. species abundance and diversity), endangerment of encompassing ecosystems, and spatial distribution of that habitat.
Habitat Restoration
Habitat restoration is a subset of habitat conservation and its goals include improving the habitat and resources ranging from one species to several species The Society for Ecological Restoration's International Science and Policy Working Group define restoration as "the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed." The scale of habitat restoration efforts can range from small to large areas of land depending on the goal of the project. Elements of habitat restoration include developing a plan and embedding goals within that plan, and monitoring and evaluating species. Considerations such as the species type, environment, and context are aspects of planning a habitat restoration project. Efforts to restore habitats that have been altered by anthropogenic activities has become a global endeavor, and is used to counteract the effects of habitat destruction by humans. Miller and Hobbs state three constraints on restoration: "ecological, economic, and social" constraints. Habitat restoration projects include Marine Debris Mitigation for Navassa Island National Wildlife Refuge in Haiti and Lemon Bay Preserve Habitat Restoration in Florida.
Identifying priority habitats for conservation
Habitat conservation is vital for protecting species and ecological processes. It is important to conserve and protect the space/ area in which that species occupies. Therefore, areas classified as ‘biodiversity hotspots’, or those in which a flagship, umbrella, or endangered species inhabits are often the habitats that are given precedence over others. Species that possess an elevated risk of extinction are given the highest priority and as a result of conserving their habitat, other species in that community are protected thus serving as an element of gap analysis. In the United States of America, a Habitat Conservation Plan (HCP) is often developed to conserve the environment in which a specific species inhabits. Under the U.S. Endangered Species Act (ESA) the habitat that requires protection in an HCP is referred to as the ‘critical habitat’. Multiple-species HCPs are becoming more favourable than single-species HCPs as they can potentially protect an array of species before they warrant listing under the ESA, as well as being able to conserve broad ecosystem components and processes . As of January 2007, 484 HCPs were permitted across the United States, 40 of which covered 10 or more species. The San Diego Multiple Species Conservation Plan (MSCP) encompasses 85 species in a total area of 26,000-km2. Its aim is to protect the habitats of multiple species and overall biodiversity by minimizing development in sensitive areas.
HCPs require clearly defined goals and objectives, efficient monitoring programs, as well as successful communication and collaboration with stakeholders and land owners in the area. Reserve design is also important and requires a high level of planning and management in order to achieve the goals of the HCP. Successful reserve design often takes the form of a hierarchical system with the most valued habitats requiring high protection being surrounded by buffer habitats that have a lower protection status. Like HCPs, hierarchical reserve design is a method most often used to protect a single species, and as a result habitat corridors are maintained, edge effects are reduced and a broader suite of species are protected.
How much habitat is needed
A range of methods and models currently exist that can be used to determine how much habitat is to be conserved in order to sustain a viable population, including Resource Selection Function and Step Selection models. Modelling tools often rely on the spatial scale of the area as an indicator of conservation value. There has been an increase in emphasis on conserving few large areas of habitat as opposed to many small areas. This idea is often referred to as the "single large or several small", SLOSS debate, and is a highly controversial area among conservation biologists and ecologists. The reasons behind the argument that "larger is better" include the reduction in the negative impacts of patch edge effects, the general idea that species richness increases with habitat area and the ability of larger habitats to support greater populations with lower extinction probabilities. Noss & Cooperrider support the "larger is better" claim and developed a model that implies areas of habitat less than 1000ha are "tiny" and of low conservation value. However, Shwartz suggests that although "larger is better", this does not imply that "small is bad". Shwartz argues that human induced habitat loss leaves no alternative to conserving small areas. Furthermore, he suggests many endangered species which are of high conservation value, may only be restricted to small isolated patches of habitat, and thus would be overlooked if larger areas were given a higher priority. The shift to conserving larger areas is somewhat justified in society by placing more value on larger vertebrate species, which naturally have larger habitat requirements.
Examples of current conservation organizations
The Nature Conservancy
Since its formation in 1951 The Nature Conservancy has slowly developed into one of the world's largest conservation organizations. Currently operating in over 30 countries, across five continents worldwide, The Nature Conservancy aims to protect nature and its assets for future generations. The organization purchases land or accepts land donations with the intention of conserving its natural resources. In 1955 The Nature Conservancy purchased its first 60-acre plot near the New York/Connecticut border in the United States of America. Today the Conservancy has expanded to protect over 119 million acres of land, 5,000 river miles as well as participating in over 1,000 marine protection programs across the globe .
Since its beginnings The Nature Conservancy has understood the benefit in taking a scientific approach towards habitat conservation. For the last decade the organization has been using a collaborative, scientific method known as "Conservation by Design." By collecting and analyzing scientific data The Conservancy is able to holistically approach the protection of various ecosystems. This process determines the habitats that need protection, specific elements that should be conserved as well as monitoring progress so more efficient practices can be developed for the future.
The Nature Conservancy currently has a large number of diverse projects in operation. They work with countries around the world to protect forests, river systems, oceans, deserts and grasslands. In all cases the aim is to provide a sustainable environment for both the plant and animal life forms that depend on them as well as all future generations to come.
World Wildlife Fund (WWF)
The World Wildlife Fund (WWF) was first formed in after a group of passionate conservationists signed what is now referred to as the Morges Manifesto. WWF is currently operating in over 100 countries across 5 continents with a current listing of over 5 million supporters.
One of the first projects of WWF was assisting in the creation of the Charles Darwin Research Foundation which aided in the protection of diverse range of unique species existing on the Galápagos’ Islands, Ecuador. It was also a WWF grant that helped with the formation of the College of African Wildlife Management in Tanzania which today focuses on teaching a wide range of protected area management skills in areas such as ecology, range management and law enforcement.
The WWF has since gone on to aid in the protection of land in Spain, creating the Coto Doñana National Park in order to conserve migratory birds and The Democratic Republic of Congo, home to the world's largest protected wetlands. The WWF also initiated a debt-for-nature concept which allows the country to put funds normally allocated to paying off national debt, into conservation programs that protect its natural landscapes. Countries currently participating include Madagascar, the first country to participate which since 1989 has generated over $US50 million towards preservation, Bolivia, Costa Rica, Ecuador, Gabon, the Philippines and Zambia.
Rare Conservation
Rare has been in operation since 1973 with current global partners in over 50 countries and offices in the United States of America, Mexico, the Philippines, China and Indonesia. Rare focuses on the human activity that threatens biodiversity and habitats such as overfishing and unsustainable agriculture. By engaging local communities and changing behaviour Rare has been able to launch campaigns to protect areas in most need of conservation.
The key aspect of Rare's methodology is their "Pride Campaigns". For example, in the Andes in South America, Rare has incentives to develop watershed protection practices. In the Southeast Asia's "coral triangle" Rare is training fishers in local communities to better manage the areas around the coral reefs in order to lessen human impact. Such programs last for three years with the aim of changing community attitudes so as to conserve fragile habitats and provide ecological protection for years to come.
WWF Netherlands
WWF Netherlands, along with ARK Nature, Wild Wonders of Europe, and Conservation Capital have started the Rewilding Europe project. This project intents to rewild several areas in Europe.
See also
Biodiversity
Biotope
Conservation biology
Conservation ethic
Ecology
Ecotope
Environment
Environmental impact of reservoirs
Environmental protection
Environmentalism
Habitat corridor
Habitat fragmentation
Marine conservation
Natural capital
Natural environment
Natural landscape
Natural resource
Nature
Recycling
Refuge (ecology)
Renewable resource
Sustainability
Sustainable agriculture
Sustainable development
Sustainable land management
Trail ethics
Water conservation
Wildlife
Wildlife corridor
Wildlife crossing
International Union for Conservation of Nature
References
External links
A-Z of Areas of Biodiversity Importance: Habitat/Species Management Area
Economics of Habitat Protection & Restoration NOAA Economics
A Technical Guide for Monitoring Wildlife Habitat U.S. Forest Service
Conservation biology
Habitats
Conservation-reliant species
Habitat
Wildlife conservation | Habitat conservation | Biology | 3,624 |
7,632,450 | https://en.wikipedia.org/wiki/P-matrix | In mathematics, a -matrix is a complex square matrix with every principal minor is positive. A closely related class is that of -matrices, which are the closure of the class of -matrices, with every principal minor 0.
Spectra of -matrices
By a theorem of Kellogg, the eigenvalues of - and - matrices are bounded away from a wedge about the negative real axis as follows:
If are the eigenvalues of an -dimensional -matrix, where , then
If , , are the eigenvalues of an -dimensional -matrix, then
Remarks
The class of nonsingular M-matrices is a subset of the class of -matrices. More precisely, all matrices that are both -matrices and Z-matrices are nonsingular -matrices. The class of sufficient matrices is another generalization of -matrices.
The linear complementarity problem has a unique solution for every vector if and only if is a -matrix. This implies that if is a -matrix, then is a -matrix.
If the Jacobian of a function is a -matrix, then the function is injective on any rectangular region of .
A related class of interest, particularly with reference to stability, is that of -matrices, sometimes also referred to as -matrices. A matrix is a -matrix if and only if is a -matrix (similarly for -matrices). Since , the eigenvalues of these matrices are bounded away from the positive real axis.
See also
Routh–Hurwitz matrix
Linear complementarity problem
M-matrix
Q-matrix
Z-matrix
Perron–Frobenius theorem
Notes
References
David Gale and Hukukane Nikaido, The Jacobian matrix and global univalence of mappings, Math. Ann. 159:81-93 (1965)
Li Fang, On the Spectra of - and -Matrices, Linear Algebra and its Applications 119:1-25 (1989)
R. B. Kellogg, On complex eigenvalues of and matrices, Numer. Math. 19:170-175 (1972)
Matrix theory
Matrices | P-matrix | Mathematics | 422 |
16,748,549 | https://en.wikipedia.org/wiki/Catawba%20Valley%20Pottery | Catawba Valley Pottery describes alkaline glazed stoneware made in the Catawba River Valley of Western North Carolina from the early 19th century, as well as certain contemporary pottery made in the region utilizing traditional methods and forms.
The earliest Catawba Valley pottery was earthenware made by the Catawba people.
At the turn of the 20th century, the food industry began to rely increasingly on glass and canned food storage along with refrigeration. These innovations brought about a severe decline of the utilitarian pottery industry nationwide, including the pottery community in Catawba Valley. Potters who chose to continue the craft had to rely on tourism and an interest in handmade crafts fostered by the American Arts and Crafts movement. Innovations included decorative techniques such as "swirl ware"; pottery made by combining two or more different colors of clay.
Glazing and firing methods
From the earliest known product, stoneware made in the Catawba Valley has been alkaline glazed. Alkaline glazes are made by combining hardwood ash or crushed glass with clay and water. Alkaline glazed stoneware takes on a brown or green color once fired in the kiln. Catawba Valley potters chose alkaline glazes over salt glaze, the predominant stoneware glaze used in America at the time. Potters enjoyed an abundance of wood ash from burning their kilns while salt deposits were not very plentiful in the Carolinas. Furthermore, salt was especially expensive during and after the Civil War.
The alkaline glazed ware was initially fired in what are known as "groundhog kilns". These kilns were a unique southern U.S. variation of climbing kilns built into hillsides, such as the Asian anagama. Semi-subterranean in construction, the groundhog kiln featured a door leading into a long, low passage of brick or rock construction, with a stack or chimney poking out of the ground uphill. Ware was loaded in the low passageway or "ware-bed" and the fire was built in a sunken firebox located just inside the door. The design allowed the stack to draw heated air, flames, and ash through the pottery grouped inside and created the draft needed to generate the intense heat required to create stoneware. This type of firing or "burning" worked particularly well with large pieces of pottery. Variations of these kilns, usually referred to as "tunnel kilns," are used by modern potters in Catawba Valley and other pottery regions in the American southeast.
Modern Potters from the Region
An early recorded pottery in the Catawba Valley was operated by Daniel Seagle (ca.1805-1867) of Lincoln County. After Seagle's death, the pottery was operated by his son and various apprentices into the 1890s.
Other notable potteries of the 19th and early 20th centuries included those operated by the Hartzogs, the Hilton family, and brothers Harvey Ford Reinhardt and Enoch William Alexander Reinhardt.
Burlon B. Craig (ca. 1914-2002) was born in Lincoln County, North Carolina and learned to make pottery as a teenager. When Craig returned from service in the Navy following World War II, he purchased the Reinhardt farm and pottery complex in Vale, North Carolina. The pottery operation included a groundhog kiln and fully equipped shop. His pottery was featured in several publications and in 1981 examples of his work were added to the Smithsonian Institution collection. In 1984 he received the National Endowment for the Arts' National Heritage Fellowship. Craig continued to live and work in Vale until his death in 2002.
In 1981 Charles Lisk and his family moved to Vale and developed a friendship with his neighbor Burlon Craig who shared with him the techniques of the Catawba Valley pottery tradition. Lisk built his own groundhog kiln and began making alkaline glazed stoneware. He makes a variety of wares including the traditional swirl pottery and face jugs.
The Reinhardt-Craig House, Kiln and Pottery Shop was listed on the National Register of Historic Places in 2008.
See also
Anagama kiln
Bartmann jug
Pottery
References
External links
Catawba Valley Pottery - History and Illustrations
Contemporary Catawba Valley Pottery
NEA Profile of Burlon Craig
American pottery
Kilns | Catawba Valley Pottery | Chemistry,Engineering | 880 |
5,100,891 | https://en.wikipedia.org/wiki/Abyss%20%28religion%29 | In the Bible, the abyss is an unfathomably deep or boundless place. The term comes from the Greek word abyssos (), meaning "bottomless, unfathomable, boundless". It is used as both an adjective and a noun. It appears in the Septuagint, which is the earliest Greek translation of the Hebrew Bible, and in the New Testament.
It translates the Hebrew words tehóm (), ṣulā ( "sea-deep, deep flood") and the name of the sea monster rahab ( "spacious place; rage, fierceness, insolence, pride.")
In the original sense of the Hebrew tehóm, the abyss was the primordial waters or chaos out of which the ordered world was created (). The term could also refer literally to the depths of the sea, the deep source of a spring or the interior of the Earth.
In a later extended sense in intertestamental Jewish literature, the abyss was the underworld, either the abode of the dead (Sheol) or eventually the realm of the rebellious spirits (fallen angels) (Hell). In the latter sense, specifically, the abyss was often seen as a prison for demons. This usage was picked up in the New Testament. According to the Gospel of Luke, Jesus sent the Gadarene swine into the abyss (). Paul of Tarsus uses the term in when quoting , referring to the abode of the dead (cf. also ). The abyss is also referred to several times in the Book of Revelation: it is the place out of which the locusts and beast from the sea come (Revelation 9:1–11; Revelation 13:1;) and serves as a prison for the Seven-Headed Dragon during the Millennium ().
In , "deep calls to deep" (referring to the waters), or in Latin abyssus abyssum invocat, developing the theme of the longing of the soul for God. Cassiodorus relates this passage to the mutual witness of the two Testaments, the Old Testament foretelling the New, and the New Testament fulfilling the Old.
In , Abaddon is called "the angel of the abyss".
On the Origin of the World, a text used in Gnosticism, states that during the end of the world, the archons will be cast into the abyss by Sophia for their injustice. There they will fight each other until only the chief archon remains and turns against himself.
See also
Abyss (Thelema)
Abzu
Cognitive closure (philosophy)
References
The Beast (Revelation)
Biblical cosmology
Book of Revelation
Chaos (cosmogony)
Hebrew Bible words and phrases
Jewish underworld
Septuagint words and phrases
Water and Christianity
Water and Judaism | Abyss (religion) | Astronomy | 569 |
58,085,116 | https://en.wikipedia.org/wiki/NGC%203883 | NGC 3883 is a large low surface brightness spiral galaxy located about 330 million light-years away in the constellation Leo. NGC 3883 has a prominent bulge but does not host an AGN. The galaxy also has flocculent spiral arms in its disk. It was discovered by astronomer William Herschel on April 13, 1785 and is a member of the Leo Cluster.
Star formation
Despite being rich in neutral atomic hydrogen (HI), NGC 3883 is very red and has a low amount of H-alpha emission. This suggests the star formation in the galaxy ended a long time ago while the inner regions continued to form stars that enriched the interstellar medium (ISM) and eventually used up the remaining gas. Possibly, the outer regions of NGC 3883 went through only a few generations of star formation because the HI density has been low throughout the galaxy's life. However, J. Donas et al. suggests that the UV emission of NGC 3883 which comes mainly from the disk of the galaxy is coming from young intermediate mass stars and reveals star formation in the outer regions of NGC 3883.
Because of a low amount of star formation ongoing in NGC 3883, it has been classified as an anemic galaxy.
See also
List of NGC objects (3001–4000)
NGC 4921, An anemic spiral galaxy in the Coma Cluster
Malin 1, A giant low surface brightness galaxy
References
External links
3883
36740
Leo (constellation)
Leo Cluster
Astronomical objects discovered in 1785
Flocculent spiral galaxies
Low surface brightness galaxies
6754 | NGC 3883 | Astronomy | 325 |
33,166,382 | https://en.wikipedia.org/wiki/Eosacantha | Eosacantha is an extinct genus of tortoise beetle in the family Chrysomelidae and containing a single species Eosacantha delocranioides. The species is known only from the Middle Eocene Parachute Member, part of the Green River Formation, in the Piceance Creek Basin, Garfield County, northwestern Colorado, USA.
History and classification
Eosacantha delocranioides is known only from one fossil, the holotype, specimen number "USNM 79136". The specimen is complete but of unidentified sex, preserved as a compression fossil in sedimentary rock. It was recovered from outcrops of the Green River Formation's Parachute Member, locality 41140, exposed in the Anvil Points area of Garfield County, Colorado, USA. The type specimen is currently preserved in the Department of Paleobiology collections housed in the National Museum of Natural History, located in Washington, D.C., USA. Eosacantha was first studied by Caroline S. Chaboo and Michael S. Engel of the University of Kansas, Lawrence, Kansas, USA. Their 2009 type description of the genus and species was published online and in print in the journal Systematic Entomology. The generic name was coined by Chaboo and Engel from a combination of the Greek () meaning "dawn" and the Greek word () meaning "thorny". The etymology of the specific epithet is in reference to the general resemblance to some modern species in the genus Delocrania.
When described, Eosacantha delocranioides along with Denaeaspis chelonopsis were among the oldest derived tortoise beetles in the fossil record. The nearest modern relatives to Eosacantha in the tribe Notosacanthini are restricted to African, tropical Asian, and Australian regions. The loss of the tribe from North America may be related to specialization of the beetles to specific plant hosts that were lost due to the extensive climatic shifts during the Late Eocene – Early Oligocene transition.
Description
The E. delocranioides type specimen is a well-preserved complete adult preserved in a dorsal view showing the antennae and head in full view. The front edge of the pronotum is deeply indented with the head and antennae visible. The elytra are preserved with a clear yellowish coloration with a darkening of the elytra towards the marginal disk. The type specimen is small: wide by long. The antennae, composed of 11 segments, are notably short in length and have an overall clavate morphology. Antennomeres seven through eleven form a weak club at the tip of the antenna.
References
Cassidinae
†
Fossil beetle genera
Eocene insects of North America
Fossil taxa described in 2009
Beetles of North America
Monotypic prehistoric insect genera
Species known from a single specimen | Eosacantha | Biology | 571 |
5,979,468 | https://en.wikipedia.org/wiki/E.B.%20Wilson%20Medal | The E.B. Wilson Medal is the American Society for Cell Biology's highest honor for science and is presented at the Annual Meeting of the Society for significant and far-reaching contributions to cell biology over the course of a career. It is named after Edmund Beecher Wilson.
Medalists
Source : ASCB
See also
List of medicine awards
References
American Society for Cell Biology
Medicine awards
Biology awards
American awards
Awards established in 1981 | E.B. Wilson Medal | Technology | 86 |
23,538,408 | https://en.wikipedia.org/wiki/Palomar%2014 | Palomar 14 is a globular cluster located in the constellation Hercules. It is a member of the Palomar Globular Clusters group. Palomar 14 was discovered in 1958 by Sidney van den Bergh and Halton Arp during inspection of the photographic plates from the Palomar Sky Survey.
This is a round, diffuse cluster located in the outer
halo of the Milky Way galaxy. It is about 3–4 billion years younger than a typical galactic cluster.
The metallicity of the cluster is [Fe/H] = −1.50, indicating a lower abundance of elements with mass greater that helium compared to the Sun. The combined mass of the main sequence stars in the cluster is , and the combined mass of observed stars within the half-light radius is . (This is the inner radius of the cluster that emits half the total luminosity.) These mass estimates provide lower bounds for determining the total mass of the cluster. The median radial velocity of stars within the cluster is .
Because of the cluster's location on the outer fringes of the Milky Way, it was used as a test case for modified newtonian dynamics (MOND). This is an alternative hypothesis to explain the galactic rotation problem.
References
Globular clusters
Astronomical objects discovered in 1958
Hercules (constellation) | Palomar 14 | Astronomy | 263 |
4,457,742 | https://en.wikipedia.org/wiki/Axel%20Firsoff | Valdemar Axel Firsoff FRAS was known principally as an amateur astronomer. He was born on 29 January 1912 in Bila Tserkva, Russian Empire, and died on 19 November 1981. He lived in Lochearnhead, Scotland, before moving to Somerset, England, where he settled in Glastonbury.
Biography
Axel Firsoff held an MA degree in languages and worked as a Swedish translator and in the United Kingdom Patent Office. He was a keen mountaineer and skier, as some of his earlier books reveal, and he was a ski instructor for the British Olympic Ski Team in the 1950s. He developed an interest in science, in particular geology and astronomy and this led him to publish numerous books on the moon and inner planets.
Many of his books also touched on extraterrestrial life and the nature of the mind. In Life, Mind and Galaxies, he speculated that "mind seems to be an entity of the same order as energy and matter", an idea well before its time. Firsoff held unorthodox views, for example he did not believe in the expansion of the universe. In other aspects of his work, such as the nature of the lunar craters, which he considered to be of volcanic rather than cosmological origin, he was later proved to be well wide of the mark.
In his book Strange World of the Moon, Firsoff suggested that there are underground oceans on the moon. Astronomer G. Fielder commented in the New Scientist magazine that most astronomers would not accept this view but as the book contains interesting new ideas it is recommended to all students of the moon.
In a 1977 review for Firsoff's book The Solar Planets in the New Scientist, Ian Ridpath commented that "the author queries the now well-established 234-day rotation period of Venus, introduces the concept of superheated steam in that planet's atmosphere, and proposes seas at the Venusian poles. An inexperienced reader, seeking reliable information on our modern knowledge of the Solar System that the book promises, will not know that these views are unorthodox."
Honors
Firsoff crater, located in Meridiani Planum on the planet Mars, is named in Firsoff's honor. Firsoff Crater is located at 2.63° North, 350.58° East.
Selected publications
Ski Track on the Battlefield - 1942
The Tatra Mountains - 1942
The Unity of Europe - 1947
The Cairngorms on Foot and Ski - 1949
Arran With Camera and Sketchbook - 1951
Our Neighbor Worlds - 1953
In the Hills of Breadalbane: Illustrated from the author's photos and drawings - 1954
Moon Atlas - 1961
The Surface of the Moon - 1961
Strange World of the Moon - 1962
The Crust Of The Earth - 1962
Life Beyond the Earth: A Study in Exobiology - 1963
Facing the Universe - 1966
Life, Mind and Galaxies - 1967
The Interior Planets - 1968
The Old Moon and the New - 1969
The World of Mars - 1969
Gemstones of the British Isles - 1971
Life among the Stars - 1974
Working with Gemstones - 1974
The Rockhound's Handbook - 1975
The Solar Planets - 1977
At the Crossroads of Knowledge - 1977
The New Face of Mars - 1982
References
Sources
Patrick Moore (1982), Obituary, Quarterly Journal of the Royal Astronomical Society, Volume 23, pp. 629–630.
Martin Mobberley (2018), The strange world of V. Axel Firsoff (1910−1981), Journal of the British Astronomical Association, Volume 128, pp. 141–156.
Preface in Life, Mind and Galaxies (1967)
Second-hand book web-sites including Amazon
Notes
1981 deaths
1910 births
Amateur astronomers
20th-century British astronomers
Soviet emigrants to the United Kingdom | Axel Firsoff | Astronomy | 766 |
33,561,630 | https://en.wikipedia.org/wiki/Cystodermella%20elegans | Cystodermella elegans is a fungus species in the genus Cystodermella. It was described in 1927 in Congo.
References
External links
Agaricaceae
Fungi described in 1927
Fungus species | Cystodermella elegans | Biology | 44 |
74,538,625 | https://en.wikipedia.org/wiki/Jean-Loup%20Delcroix | Jean-Loup Delcroix (1924–2003) was a French physicist, specializing in the physics of gases and plasmas.
Biography
Jean-Loup Delcroix received secondary education at Lycée Janson-de-Sailly in Paris and Lycée Champollion in Grenoble. He matriculated in 1944 at ENS Paris and graduated there in 1948 with outstanding rank in the agrégation in physics. He graduated in 1953 with a doctorate from the University of Paris. His thesis is entitled Étude des propriétés statiques des charges d'espace du type magnétron. Under the supervision of Yves Rocard, he participated in the construction and start-up of the linear accelerator at Orsay from 1952 until 1960. At Paris-Sud University he was a maître de conférences (MCF) from 1960 to 1965 and a professor from 1965 to 1990, when he retired as professor emeritus. In 1960 Delcroix formed Paris-Sud University's Laboratoire de Physique des Gaz et des Plasmas (LPGP), in association with the CNRS. He was the laboratory's director from 1960 to 1984. He made important contributions to the physics of gas discharges and low-temperature plasmas. During the early 1970s he led a research group on gas discharges with applications to gas laser physics.
At Paris-Sud University, Delcroix created in 1960 a graduate curriculum in plasma physics at the level of the diplôme d’études approfondies (DEA). His curriculum became a model at other French universities. His lectures on plasma physics formed the basis of three monographs originally published from 1959 to 1966. In 1961 with Jean-François Denisse, he published an important monograph on waves in plasmas. Delcroix, in collaboration with Abraham Bers (1930–2015), wrote a two-volume textbook entitled Physique des Plasmas, published in 1994.
From 1965 to 1976 Delcroix was the director of scientific research for the Direction des Recherches et Moyens d’Essai (D.R.M.E.), France's agency for development and coordination of military research. The D.R.M.E. was created in 1961 by Lucien Malavard (1910–1990). From 1978 to 1989 Delcroix was the Director General of the École supérieure d'électricité (Supélec). Under his directorship, Supélec expanded to three campuses and modernized its curriculum. From 1982 to 2003 he was France's representative to the Committee on Data of the International Science Council (CODATA). Beginning in 1975, Delacroix with several colleagues created and maintained GAPHYOR (GAz PHysique ORsay), a database and computerized retrieval system for atomic and molecular physics.
The French government appointed him Chevalier des Palmes académiques (1966), Chevalier de la Légion d'honneur (1969), Commandeur de l'ordre national du Mérite (1984), and Officier de la Legion d'honneur (1989).
He and his first wife had a son and two daughters. After divorce from his first wife, J.-L. Delcroix remarried and became the stepfather of one child. He was predeceased by his second wife.
Articles
Books
; translated into English:
; translated into English:
; translated into English:
with Abraham Bers: Physique des plasmas, EDP Sciences, 1994;
References
1924 births
2003 deaths
Plasma physicists
20th-century French physicists
École Normale Supérieure alumni
University of Paris alumni
Academic staff of Paris-Sud University
Officers of the Legion of Honour | Jean-Loup Delcroix | Physics | 768 |
50,143,193 | https://en.wikipedia.org/wiki/Badlock | Badlock () is a security bug disclosed on April 12, 2016 affecting the Security Account Manager (SAM) and Local Security Authority (Domain Policy) (LSAD) remote protocols supported by Windows and Samba servers.
Both SAM and LSAD are layered onto the DCE 1.1 Remote Procedure Call (DCE/RPC) protocol. As implemented in Samba and Windows, the RPC services allowed an attacker to become man in the middle. Although the vulnerability was discovered during the development of Samba, the namegiving SMB protocol itself is not affected.
References
External links
2016 in computing
Internet security
Software bugs
Computer security exploits | Badlock | Technology | 129 |
19,763,060 | https://en.wikipedia.org/wiki/Slater%E2%80%93Condon%20rules | Within computational chemistry, the Slater–Condon rules express integrals of one- and two-body operators over wavefunctions constructed as Slater determinants of orthonormal orbitals in terms of the individual orbitals. In doing so, the original integrals involving N-electron wavefunctions are reduced to sums over integrals involving at most two molecular orbitals, or in other words, the original 3N dimensional integral is expressed in terms of many three- and six-dimensional integrals.
The rules are used in deriving the working equations for all methods of approximately solving the Schrödinger equation that employ wavefunctions constructed from Slater determinants. These include Hartree–Fock theory, where the wavefunction is a single determinant, and all those methods which use Hartree–Fock theory as a reference such as Møller–Plesset perturbation theory, and Coupled cluster and Configuration interaction theories.
In 1929 John C. Slater derived expressions for diagonal matrix elements of an approximate Hamiltonian while investigating atomic spectra within a perturbative approach. The following year Edward Condon extended the rules to non-diagonal matrix elements. In 1955 Per-Olov Löwdin further generalized these results for wavefunctions constructed from non-orthonormal orbitals, leading to what are known as the Löwdin rules.
Mathematical background
In terms of an antisymmetrization operator () acting upon a product of N orthonormal spin-orbitals (with r and σ denoting spatial and spin variables), a determinantal wavefunction is denoted as
A wavefunction differing from this by only a single orbital (the m'''th orbital) will be denoted as
and a wavefunction differing by two orbitals will be denoted as
For any particular one- or two-body operator, Ô, the Slater–Condon rules show how to simplify the following types of integrals:
Matrix elements for two wavefunctions differing by more than two orbitals vanish unless higher order interactions are introduced.
Integrals of one-body operators
One body operators depend only upon the position or momentum of a single electron at any given instant. Examples are the kinetic energy, dipole moment, and total angular momentum operators.
A one-body operator in an N-particle system is decomposed as
The Slater–Condon rules for such an operator are:
Integrals of two-body operators
Two-body operators couple two particles at any given instant. Examples being the electron-electron repulsion, magnetic dipolar coupling, and total angular momentum-squared operators.
A two-body operator in an N''-particle system is decomposed as
The Slater–Condon rules for such an operator are:
where
Any matrix elements of a two-body operator with wavefunctions that differ in three or more spin orbitals will vanish, meaning
References
Computational chemistry
Quantum chemistry | Slater–Condon rules | Physics,Chemistry | 604 |
367,896 | https://en.wikipedia.org/wiki/List%20of%20biomolecules | This is a list of articles that describe particular biomolecules or types of biomolecules.
A
For substances with an A- or α- prefix such as
α-amylase, please see the parent page (in this case Amylase).
A23187 (Calcimycin, Calcium Ionophore)
Abamectine
Abietic acid
Acetic acid
Acetylcholine
Actin
Actinomycin D
Adenine
Adenosmeme
Adenosine diphosphate (ADP)
Adenosine monophosphate (AMP)
Adenosine triphosphate (ATP)
Adenylate cyclase
Adiponectin
Adonitol
Adrenaline, epinephrine
Adrenocorticotropic hormone (ACTH)
Aequorin
Aflatoxin
Agar
Alamethicin
Alanine
Albumins
Aldosterone
Aleurone
Alpha-amanitin
Alpha-MSH (Melaninocyte stimulating hormone)
Allantoin
Allethrin
α-Amanatin, see Alpha-amanitin
Amino acid
Amylase (also see α-amylase)
Anabolic steroid
Anandamide (ANA)
Androgen
Anethole
Angiotensinogen
Anisomycin
Antidiuretic hormone (ADH)
Anti-Müllerian hormone (AMH)
Arabinose
Arginine
Argonaute
Ascomycin
Ascorbic acid (vitamin C)
Asparagine
Aspartic acid
Asymmetric dimethylarginine
ATP synthase
Atrial-natriuretic peptide (ANP)
Auxin
Avidin
Azadirachtin A – C35H44O16
B
Bacteriocin
Beauvericin
beta-Hydroxy beta-methylbutyric acid
beta-Hydroxybutyric acid
Bicuculline
Bilirubin
Biopolymer
Biotin (Vitamin H)
Brefeldin A
Brassinolide
Brucine
Butyric acid
C
Cadaverine
Caffeine
Calciferol (Vitamin D)
Calcitonin
Calmodulin
Calreticulin
Camphor - (C10H16O)
Cannabinol - (C21H26O2)
Capsaicin
Carbohydrase
Carbohydrate
Carnitine
Carrageenan
Carotinoid
Casein
Caspase
Catecholamine
Cellulase
Cellulose - (C6H10O5)x
Cerulenin
Cetrimonium bromide (Cetrimide) - C19H42BrN
Chelerythrine
Chromomycin A3
Chaparonin
Chitin
α-Chloralose
Chlorophyll
Cholecystokinin (CCK)
Cholesterol
Choline
Chondroitin sulfate
Cinnamaldehyde
Citral
Citric acid
Citrinin
Citronellal
Citronellol
Citrulline
Cobalamin (vitamin B12)
Coenzyme
Coenzyme Q
Colchicine
Collagen
Coniine
Corticosteroid
Corticosterone
Corticotropin-releasing hormone (CRH)
Cortisol
Creatine
Creatine kinase
Crystallin
Cyclic adenosine monophosphate (cAMP)
α-Cyclodextrin
Cyclodextrin glycosyltransferase
Cyclooxygenase
Cyclopamine
Cyclopiazonic acid
Cysteine
Cystine
Cytidine
Cytochalasin
Cytochalasin E
Cytochrome
Cytochrome C
Cytochrome c oxidase
Cytochrome c peroxidase
Cytokine
Cytosine – C4H5N3O
D
Dehydroepiandrosterone (DHEA)
Deoxycholic acid
DON (DeoxyNivalenol)
Deoxyribofuranose
Deoxyribose
Deoxyribonucleic acid (DNA)
Dextran
Dextrin
Dicer
Dihydrotestosterone
DNA
DNA polymerase
DNA ligase
Dopamine
E
Endonuclease
Enzyme
Ephedrine
Epinephrine – C9H13NO3
Erucic acid – CH3(CH2)7CH=CH(CH2)11COOH
Erythritol
Erythropoietin (EPO)
Estradiol
Estriol
Estrogen
Estrone
Eugenol
Exonuclease
F
Fatty acid
Ferredoxin
Fibrin
Fibronectin
Flavin adenine dinucleotide (FAD)
Folic acid (Vitamin M)
Follicle stimulating hormone (FSH)
Formaldehyde
Formic acid
Formnoci
Fructose
Fumonisin B1
G
Galactose
Gangalioside
Gamma globulin
Gamma-aminobutyric acid
Gamma-butyrolactone
Gamma-hydroxybutyrate (GHB)
Gastrin
Gelatin
Geraniol
Ghrelin
Globulin
Glucagon
Glucagon-like peptide 1
Glucagon-like peptide 2
Glucosamine
Glucose – C6H12O6
Glucose oxidase
Glutamic acid
Glutamine
Glutamate (neurotransmitter)
Glutathione
Gluten
Glycan
Glycerin (glycerol)
Glycine
Glycogen
Glycogenin
Glycogen synthase
Glycogen phosphorylase
Glycolic acid
Glycolipid
Glycoprotein
Gonadotropin-releasing hormone (GnRH)
Granzyme
Green fluorescent protein
Growth factor
Growth hormone
Growth hormone-releasing hormone (GHRH)
GTPase
Guanine
Guanosine
Guanosine triphosphate (+GTP)
Gurungase
H
Haptoglobin
Helicase
Hematoxylin
Heme
Hemerythrin
Hemocyanin
Hemoglobin
Hemoprotein
Heparan sulfate
High density lipoprotein, HDL
Histamine
Histidine
Histone
Histone methyltransferase
HLA antigen
Homocysteine
Hormone
human chorionic gonadotropin (hCG)
Human growth hormone
Hyaluronate
Hyaluronic acid
Hyaluronidase
Hydrogen peroxide
5-Hydroxymethylcytosine
Hydroxyproline
5-Hydroxytryptamine
I
Indigo dye
Indole
Inosine
Inositol
Insulin
Insulin-like growth factor
Integral membrane protein
Integrase
Integrin
Intein
Interferon
Interleukin
Inulin
Ionomycin
Ionone
Isoleucine
Isomerase
Isoprene
Iron–sulfur cluster
J
Jipitol
K
K252a
K252b
KT5720
KT5823
Keratin
Kinase
Kisspeptin
Kouhestanimine
L
For substances with an l- or L- prefix such as L-alanine or DL-alanine, please see the parent page (in this case alanine).
Lactase
Lactic acid
Lactose
Lanolin
Lauric acid
Lectin
Leptin
Leptomycin B
Leucine
Leukotriene
Ligase
Lignin
Limonene
Linalool
Linoleic acid
Linolenic acid
Lipase
Lipid
Lipid anchored protein
Lipoamide
Lipoprotein
Low density lipoprotein, LDL
Luteinizing hormone (LH)
Lycopene
Lysine
Lysozyme
M
Malic acid
Maltose
Melanocyte- stimulating hormone (MSH)
Melatonin
Membrane protein
Messenger RNA (mRNA)
Metalloprotein
Metallothionein
Methionine
Mimosine
Mithramycin A
Mitomycin C
Monomer
Morphine
Mycophenolic acid
Myoglobin
Myosin
Mersalase
Milnolate
N
Natural phenols
Neurotransmitters
Neuropeptide Y
Nicotinamide adenine dinucleotide (NAD)
Norepinephrine
Nucleic Acid
Nucleosome
Nucleoside
Nucleotide
O
Ochratoxin A
Oestrogens
Oligopeptide
Oligomycin
Orcin
Orexin
Ornithine
Oxalic acid
Oxidase
Oxytocin
P
p53
PABA
Paclitaxel
Palmitic acid
Pantothenic acid (vitamin B5)
parathyroid hormone (PTH)
Paraprotein
Pardaxin
Parthenolide
Patulin
Paxilline
Penicillic acid
Penicillin
Penitrem A
Peptidase
Peptide YY (PYY)
Pepsin
Peptide
Perimycin
Peripheral membrane protein
Perosamine
Phenethylamine
Phenylalanine
Phosphagen
phosphatase
Phosphatidyl choline
Phospholipid
Phenylalanine
Phytic acid
Plant hormones
Plasma protein
Plastocyanin
Polypeptide
Polyphenols
Polysaccharides
Porphyrin
Pranavylate Kinase Kinase
Prion
Progesterone
Prolactin (PRL)
Proline
Propionic acid
Prostaglandins
Protamine
Protease
Proteasome
Protein
Proteinoid
Purine
Putrescine
Pyrethrin
Pyridoxine or pyridoxamine (Vitamin B6)
Pyrimidine
Pyrrolysine
Pyruvic acid
Q
Quinidine
Quinine
Quinone
R
Radicicol
Raffinose
Relaxin
Renin
Retinene
Retinol (Vitamin A)
Reverse transcriptase
Rhodopsin (visual purple)
Riboflavin (vitamin B2)
Ribofuranose, Ribose
Ribozyme
Ricin
RNA - Ribonucleic acid
RNA polymerase
RuBisCO
Ribosomal RNA
S
Safrole
Salicylaldehyde
Salicylic acid
Salvinorin-A – C23H28O8
Saponin
Secretin
Selenocysteine
Selenomethionine
Selenoprotein
Serine
Serine kinase
Serotonin
Skatole
Signal recognition particle
Somatostatin
Sorbic acid
Sphingolipid
Sphingosine
Squalene
Staurosporin
Stearic acid
Sterigmatocystin
Sterol
Strychnine
Sucrose (sugar)
Sugars (in general)
superoxide
T
T2 Toxin
Tannic acid
Tannin
Tartaric acid
Taurine
Tetrodotoxin
Telomerase
Thaumatin
Topoisomerase
Tyrosine kinase
Testosterone
Tetrahydrocannabinol (THC)
Tetracycline
Thapsigargin
Thaumatin
Thiamine (vitamin B1) – C12H17ClN4OS·HCl
Threonine
Thrombopoietin
Thromboxane
Thymidine
Thymine
Transfer RNA (tRNA)
Triacsin C
Thyroid-stimulating hormone (TSH)
Thyrotropin-releasing hormone (TRH)
Thyroxine (T4)
Tocopherol (Vitamin E)
Topoisomerase
Triiodothyronine (T3)
Transmembrane receptor
Trichostatin A
Trophic hormone
Trypsin
Tryptophan
Tubulin
Tunicamycin
Tyrosine
U
Ubiquitin
Uracil
Urea
Urease
Uric acid – C5H4N4O3
Uridine
V
Valine
Valinomycin
Vanabins
Vasopressin
Verruculogen
Vitamins (in general)
Vitamin A (retinol)
Vitamin B
Vitamin B1 (thiamine)
Vitamin B2 (riboflavin)
Vitamin B3 (niacin or nicotinic acid)
Vitamin B4 (adenine)
Vitamin B5 (pantothenic acid)
Vitamin B6 (pyridoxine or pyridoxamine)
Vitamin B12 (cobalamin)
Vitamin C (ascorbic acid)
Vitamin D (calciferol)
Vitamin E (tocopherol)
Vitamin F
Vitamin H (biotin)
Vitamin K (naphthoquinone)
Vitamin M (folic acid)
W
Water
Wortmannin
X
Xanthophyll
Xylose
Y
Yellow fluorescent protein
Z
Zearalenone
See also
Chemical compound
Organic compound
biochemistry
Similar lists
List of compounds
List of organic compounds
List of proteins
Biomolecules
Biomolecules
Biomolecules
cs:Biomolekula#Typy biomolekul
fr:Liste alphabétique de biomolécules | List of biomolecules | Chemistry,Biology | 2,581 |
49,449,732 | https://en.wikipedia.org/wiki/PROTO%20%28fusion%20reactor%29 | PROTO is a proposed nuclear fusion reactor to be implemented after 2050, a successor to the ITER and DEMO projects. It is part of the European Commission long-term strategy for research of fusion energy. PROTO would act as a prototype power station, taking in any technology refinements from earlier projects, and demonstrating electricity generation on a commercial basis. It may or may not be a second part of DEMO/PROTO experiment.
References
Tokamaks
Proposed fusion reactors
ITER | PROTO (fusion reactor) | Physics | 96 |
8,095 | https://en.wikipedia.org/wiki/Donald%20Knuth | Donald Ervin Knuth ( ; born January 10, 1938) is an American computer scientist and mathematician. He is a professor emeritus at Stanford University. He is the 1974 recipient of the ACM Turing Award, informally considered the Nobel Prize of computer science. Knuth has been called the "father of the analysis of algorithms".
Knuth is the author of the multi-volume work The Art of Computer Programming. He contributed to the development of the rigorous analysis of the computational complexity of algorithms and systematized formal mathematical techniques for it. In the process, he also popularized the asymptotic notation. In addition to fundamental contributions in several branches of theoretical computer science, Knuth is the creator of the TeX computer typesetting system, the related METAFONT font definition language and rendering system, and the Computer Modern family of typefaces.
As a writer and scholar, Knuth created the WEB and CWEB computer programming systems designed to encourage and facilitate literate programming, and designed the MIX/MMIX instruction set architectures. He strongly opposes the granting of software patents, and has expressed his opinion to the United States Patent and Trademark Office and European Patent Organisation.
Biography
Early life
Donald Knuth was born in Milwaukee, Wisconsin, to Ervin Henry Knuth and Louise Marie Bohning. He describes his heritage as "Midwestern Lutheran German". His father owned a small printing business and taught bookkeeping. While a student at Milwaukee Lutheran High School, Knuth thought of ingenious ways to solve problems. For example, in eighth grade, he entered a contest to find the number of words that the letters in "Ziegler's Giant Bar" could be rearranged to create; the judges had identified 2,500 such words. With time gained away from school due to a fake stomachache, Knuth used an unabridged dictionary and determined whether each dictionary entry could be formed using the letters in the phrase. Using this algorithm, he identified over 4,500 words, winning the contest. As prizes, the school received a new television and enough candy bars for all of his schoolmates to eat.
Education
Knuth received a scholarship in physics to the Case Institute of Technology (now part of Case Western Reserve University) in Cleveland, Ohio, enrolling in 1956. He also joined the Beta Nu Chapter of the Theta Chi fraternity. While studying physics at Case, Knuth was introduced to the IBM 650, an early commercial computer. After reading the computer's manual, Knuth decided to rewrite the assembly and compiler code for the machine used in his school because he believed he could do it better.
In 1958, Knuth created a program to help his school's basketball team win its games. He assigned "values" to players in order to gauge their probability of scoring points, a novel approach that Newsweek and CBS Evening News later reported on.
Knuth was one of the founding editors of the Case Institute's Engineering and Science Review, which won a national award as best technical magazine in 1959. He then switched from physics to mathematics, and received two degrees from Case in 1960: his Bachelor of Science, and simultaneously a master of science by a special award of the faculty, who considered his work exceptionally outstanding.
At the end of his senior year at Case in 1960, Knuth proposed to Burroughs Corporation to write an ALGOL compiler for the B205 for $5,500. The proposal was accepted and he worked on the ALGOL compiler between graduating from Case and going to Caltech.
In 1963, with mathematician Marshall Hall as his adviser, he earned a PhD in mathematics from the California Institute of Technology, with a thesis titled Finite Semifields and Projective Planes.
Early work
In 1963, after receiving his PhD, Knuth joined Caltech's faculty as an assistant professor.
While at Caltech and after the success of the Burroughs B205 ALGOL compiler, he became consultant to Burroughs Corporation, joining the Product Planning Department. At Caltech he was operating as a mathematician but at Burroughs as a programmer working with the people he considered to have written the best software at the time in the ALGOL compiler for the B220 computer (successor to the B205).
He was offered a $100,000 contract to write compilers at Green Tree Corporation but turned it down making a decision not to optimize income and continued at Caltech and Burroughs.
He received a National Science Foundation Fellowship and Woodrow Wilson Foundation Fellowship but they had the condition that you could not do anything else but study as a graduate student so he would not be able to continue as a consultant to Burroughs. He chose to turn down the fellowships and continued with Burroughs.
In summer 1962, he wrote a FORTRAN compiler for Univac, but considered that “I sold my soul to the devil” to write a FORTRAN compiler.
After graduating, Knuth returned to Burroughs in June 1961 but did not tell them he had graduated with a master's degree, rather than the expected bachelor's degree. Impressed by the ALGOL syntax chart, symbol table, recursive-descent approach and the separation of the scanning, parsing and emitting functions of the compiler Knuth suggested an extension to the symbol table that one symbol could stand for a string of symbols. This became the basis of the DEFINE in Burroughs ALGOL, which has since been adopted by other languages. However, some really disliked the idea and wanted DEFINE removed. The last person to think it was a terrible idea was Edsger Dijkstra on a visit to Burroughs.
Knuth worked on simulation languages at Burroughs producing SOL ‘Simulation Oriented Language’, an improvement on the state-of-the-art, co-designed with J. McNeeley. He attended a conference in Norway in May, 1967 organised by the people who invented the Simula language. Knuth influenced Burroughs to use Simula.
Knuth had a long association with Burroughs as a consultant from 1960 to 1968 until his move into more academic work at Stanford in 1969.
In 1962, Knuth accepted a commission from Addison-Wesley to write a book on computer programming language compilers. While working on this project, he decided that he could not adequately treat the topic without first developing a fundamental theory of computer programming, which became The Art of Computer Programming. He originally planned to publish this as a single book, but as he developed his outline for the book, he concluded that he required six volumes, and then seven, to thoroughly cover the subject. He published the first volume in 1968.
Just before publishing the first volume of The Art of Computer Programming, Knuth left Caltech to accept employment with the Institute for Defense Analyses' Communications Research Division, then situated on the Princeton campus, which was performing mathematical research in cryptography to support the National Security Agency.
In 1967, Knuth attended a Society for Industrial and Applied Mathematics conference and someone asked what he did. At the time, computer science was partitioned into numerical analysis, artificial intelligence, and programming languages. Based on his study and The Art of Computer Programming book, Knuth decided the next time someone asked he would say, "Analysis of algorithms".
In 1969, Knuth left his position at Princeton to join the Stanford University faculty, where he became Fletcher Jones Professor of Computer Science in 1977. He became Professor of The Art of Computer Programming in 1990, and has been emeritus since 1993.
Writings
Knuth is a writer as well as a computer scientist.
The Art of Computer Programming (TAOCP)
In the 1970s, Knuth called computer science "a totally new field with no real identity. And the standard of available publications was not that high. A lot of the papers coming out were quite simply wrong. ... So one of my motivations was to put straight a story that had been very badly told."
From 1972 to 1973, Knuth spent a year at the University of Oslo among people such as Ole-Johan Dahl. This is where he had originally intended to write the seventh volume in his book series, which was to deal with programming languages. But Knuth had finished only the first two volumes when he came to Oslo, and thus spent the year on the third volume, next to teaching. The third volume came out just after Knuth returned to Stanford in 1973.
Concrete Mathematics: A Foundation for Computer Science originated with an expansion of the mathematical preliminaries section of Volume 1 of TAoCP. Knuth found that there were mathematical tools necessary for Volume 1, but missing from his repertoire, and decided that a course introducing those tools to computer science students would be useful. Knuth introduced the course at Stanford in 1970. Course notes developed by Oren Patashnik evolved into the 1988 text, with authors Ronald Graham, Knuth, and Patashnik. A second edition of Concrete Mathematics was published in 1994.
By 2011, Volume 4A of TAoCP had been published. In April 2020, Knuth said he anticipated that Volume 4 of TAoCP will have at least parts A through F. Volume 4B was published in October 2022.
Other works
Knuth is also the author of Surreal Numbers, a mathematical novelette on John Horton Conway's set theory construction of an alternate system of numbers. Instead of simply explaining the subject, the book seeks to show the development of the mathematics. Knuth wanted the book to prepare students for doing original, creative research.
In 1995, Knuth wrote the foreword to the book A=B by Marko Petkovšek, Herbert Wilf and Doron Zeilberger. He also occasionally contributes language puzzles to Word Ways: The Journal of Recreational Linguistics.
Knuth has delved into recreational mathematics. He contributed articles to the Journal of Recreational Mathematics beginning in the 1960s, and was acknowledged as a major contributor in Joseph Madachy's Mathematics on Vacation.
Knuth also appears in a number of Numberphile and Computerphile videos on YouTube, where he discusses topics from writing Surreal Numbers to why he does not use email.
Knuth had proposed the name "algorithmics" as a better name for the discipline of computer science.
Works about his religious beliefs
In addition to his writings on computer science, Knuth, a Lutheran, is also the author of 3:16 Bible Texts Illuminated, in which he examines the Bible by a process of systematic sampling, namely an analysis of chapter 3, verse 16 of each book. Each verse is accompanied by a rendering in calligraphic art, contributed by a group of calligraphers led by Hermann Zapf. Knuth was invited to give a set of lectures at MIT on the views on religion and computer science behind his 3:16 project, resulting in another book, Things a Computer Scientist Rarely Talks About, where he published the lectures God and Computer Science.
Opinion on software patents
Knuth strongly opposes granting software patents to trivial solutions that should be obvious, but has expressed more nuanced views for nontrivial solutions such as the interior-point method of linear programming. He has expressed his disagreement directly to both the United States Patent and Trademark Office and European Patent Organisation.
Programming
Digital typesetting
In the 1970s, the publishers of TAOCP abandoned Monotype in favor of phototypesetting. Knuth became so frustrated with the inability of the latter system to approach the quality of the previous volumes, which were typeset using the older system, that he took time out to work on digital typesetting and created TeX and Metafont.
Literate programming
While developing TeX, Knuth created a new methodology of programming, which he called literate programming, because he believed that programmers should think of programs as works of literature:
Knuth embodied the idea of literate programming in the WEB system. The same WEB source is used to weave a TeX file, and to tangle a Pascal source file. These in their turn produce a readable description of the program and an executable binary respectively. A later iteration of the system, CWEB, replaces Pascal with C, C++, and Java.
Knuth used WEB to program TeX and METAFONT, and published both programs as books, both originally published the same year: TeX: The Program (1986); and METAFONT: The Program (1986). Around the same time, LaTeX, the now-widely adopted macro package based on TeX, was first developed by Leslie Lamport, who later published its first user manual in 1986.
Personal life
Donald Knuth married Nancy Jill Carter on 24 June 1961, while he was a graduate student at the California Institute of Technology. They have two children: John Martin Knuth and Jennifer Sierra Knuth.
Knuth gives informal lectures a few times a year at Stanford University, which he calls "Computer Musings". He was a visiting professor at the Oxford University Department of Computer Science in the United Kingdom until 2017 and an Honorary Fellow of Magdalen College.
Knuth is an organist and a composer. He and his father served as organists for Lutheran congregations. Knuth and his wife have a 16-rank organ in their home. In 2016 he completed a piece for organ, Fantasia Apocalyptica, which he calls a "translation of the Greek text of the Revelation of Saint John the Divine into music". It was premièred in Sweden on January 10, 2018.
Chinese name
Knuth's Chinese name is Gao Dena (). He was given this name in 1977 by Frances Yao shortly before making a three-week trip to China. In the 1980 Chinese translation of Volume 1 of The Art of Computer Programming (), Knuth explains that he embraced his Chinese name because he wanted to be known by the growing numbers of computer programmers in China at the time. In 1989, his Chinese name was placed atop the Journal of Computer Science and Technology header, which Knuth says "makes me feel close to all Chinese people although I cannot speak your language".
Humor
Knuth used to pay a finder's fee of $2.56 for any typographical errors or mistakes discovered in his books, because "256 pennies is one hexadecimal dollar", and $0.32 for "valuable suggestions". According to an article in the Massachusetts Institute of Technology's Technology Review, these Knuth reward checks are "among computerdom's most prized trophies". Knuth had to stop sending real checks in 2008 due to bank fraud, and now gives each error finder a "certificate of deposit" from a publicly listed balance in his fictitious "Bank of San Serriffe".
He once warned a correspondent, "Beware of bugs in the above code; I have only proved it correct, not tried it."
Knuth published his first "scientific" article in a school magazine in 1957 under the title "The Potrzebie System of Weights and Measures". In it, he defined the fundamental unit of length as the thickness of Mad No. 26, and named the fundamental unit of force "whatmeworry". Mad published the article in issue No. 33 (June 1957).
To demonstrate the concept of recursion, Knuth intentionally referred "Circular definition" and "Definition, circular" to each other in the index of The Art of Computer Programming, Volume 1.
The preface of Concrete Mathematics has the following paragraph:
At the TUG 2010 Conference, Knuth announced a satirical XML-based successor to TeX, titled "iTeX" (, performed with a bell ringing), which would support features such as arbitrarily scaled irrational units, 3D printing, input from seismographs and heart monitors, animation, and stereophonic sound.
Awards and honors
In 1971, Knuth received the first ACM Grace Murray Hopper Award. He has received various other awards, including the Turing Award, the National Medal of Science, the John von Neumann Medal, and the Kyoto Prize.
Knuth was elected a Distinguished Fellow of the British Computer Society (DFBCS) in 1980 in recognition of his contributions to the field of computer science.
In 1990, he was awarded the one-of-a-kind academic title Professor of The Art of Computer Programming; the title has since been revised to Professor Emeritus of The Art of Computer Programming.
Knuth was elected to the National Academy of Sciences in 1975. He was also elected a member of the National Academy of Engineering in 1981 for organizing vast subject areas of computer science so that they are accessible to all segments of the computing community. In 1992, he became an associate of the French Academy of Sciences. Also that year, he retired from regular research and teaching at Stanford University in order to finish The Art of Computer Programming. He was elected a Foreign Member of the Royal Society (ForMemRS) in 2003.
Knuth was elected as a Fellow (first class of Fellows) of the Society for Industrial and Applied Mathematics in 2009 for his outstanding contributions to mathematics. He is a member of the Norwegian Academy of Science and Letters. In 2012, he became a fellow of the American Mathematical Society and a member of the American Philosophical Society. Other awards and honors include:
First ACM Grace Murray Hopper Award, 1971
Turing Award, 1974
Lester R. Ford Award, 1975 and 1993
Josiah Willard Gibbs Lecturer, 1978
National Medal of Science, 1979
Golden Plate Award of the American Academy of Achievement, 1985
Franklin Medal, 1988
John von Neumann Medal, 1995
Harvey Prize from the Technion, 1995
Kyoto Prize, 1996
Fellow of the Computer History Museum "for his fundamental early work in the history of computing algorithms, development of the TeX typesetting language, and for major contributions to mathematics and computer science." 1998
Asteroid 21656 Knuth, named in his honor in May 2001
Katayanagi Prize, 2010
BBVA Foundation Frontiers of Knowledge Award in the category of Information and Communication Technologies, 2010
Turing Lecture, 2011
Stanford University School of Engineering Hero Award, 2011
Flajolet Lecture Prize, 2014
Publications
A short list of his publications include:
The Art of Computer Programming:
Computers and Typesetting (all books are hardcover unless otherwise noted):
, x+483pp.
(softcover).
, xviii+600pp.
, xii+361pp.
(softcover).
, xviii+566pp.
, xvi+588pp.
Books of collected papers:
, (paperback)
, (paperback)
Donald E. Knuth, Selected Papers on Design of Algorithms (Stanford, California: Center for the Study of Language and Information—CSLI Lecture Notes, no. 191), 2010. (cloth), (paperback)
Donald E. Knuth, Selected Papers on Fun and Games (Stanford, California: Center for the Study of Language and Information—CSLI Lecture Notes, no. 192), 2011. (cloth), (paperback)
Donald E. Knuth, Companion to the Papers of Donald Knuth (Stanford, California: Center for the Study of Language and Information—CSLI Lecture Notes, no. 202), 2011. (cloth), (paperback)
Other books:
xiv+657 pp.
Donald E. Knuth, The Stanford GraphBase: A Platform for Combinatorial Computing (New York, ACM Press) 1993. second paperback printing 2009.
Donald E. Knuth, 3:16 Bible Texts Illuminated (Madison, Wisconsin: A-R Editions), 1990.
Donald E. Knuth, Things a Computer Scientist Rarely Talks About (Center for the Study of Language and Information—CSLI Lecture Notes no 136), 2001.
Donald E. Knuth, MMIXware: A RISC Computer for the Third Millennium (Heidelberg: Springer-Verlag— Lecture Notes in Computer Science, no. 1750), 1999. viii+550pp.
Donald E. Knuth and Silvio Levy, The CWEB System of Structured Documentation (Reading, Massachusetts: Addison-Wesley), 1993. iv+227pp. . Third printing 2001 with hypertext support, ii + 237 pp.
Donald E. Knuth, Tracy L. Larrabee, and Paul M. Roberts, Mathematical Writing (Washington, D.C.: Mathematical Association of America), 1989. ii+115pp
Daniel H. Greene and Donald E. Knuth, Mathematics for the Analysis of Algorithms (Boston: Birkhäuser), 1990. viii+132pp.
Donald E. Knuth, , 1976. 106pp.
Donald E. Knuth, Stable Marriage and Its Relation to Other Combinatorial Problems: An Introduction to the Mathematical Analysis of Algorithms.
Donald E. Knuth, Axioms and Hulls (Heidelberg: Springer-Verlag—Lecture Notes in Computer Science, no. 606), 1992. ix+109pp.
See also
Asymptotic notation
Attribute grammar
CC system
Dancing Links
Knuth -yllion
Knuth–Bendix completion algorithm
Knuth Prize
Knuth shuffle
Knuth's Algorithm X
Knuth's Simpath algorithm
Knuth's up-arrow notation
Knuth–Morris–Pratt algorithm
Davis–Knuth dragon
Bender–Knuth involution
Trabb Pardo–Knuth algorithm
Fisher–Yates shuffle
Robinson–Schensted–Knuth correspondence
Man or boy test
Plactic monoid
Quater-imaginary base
TeX
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Recipients of Franklin Medal | Donald Knuth | Mathematics | 4,654 |
1,781,678 | https://en.wikipedia.org/wiki/Cocktail%20party%20effect | The cocktail party effect refers to a phenomenon wherein the brain focuses a person's attention on a particular stimulus, usually auditory. This focus excludes a range of other stimuli from conscious awareness, as when a partygoer follows a single conversation in a noisy room. This ability is widely distributed among humans, with most listeners more or less easily able to portion the totality of sound detected by the ears into distinct streams, and subsequently to decide which streams are most pertinent, excluding all or most others.
It has been proposed that a person's sensory memory subconsciously parses all stimuli and identifies discrete portions of these sensations according to their salience. This allows most people to tune effortlessly into a single voice while tuning out all others. The phenomenon is often described as a "selective attention" or "selective hearing". It may also describe a similar phenomenon that occurs when one may immediately detect words of importance originating from unattended stimuli, for instance hearing one's name among a wide range of auditory input.
A person who lacks the ability to segregate stimuli in this way is often said to display the cocktail party problem or cocktail party deafness. This may also be described as auditory processing disorder or King-Kopetzky syndrome.
Neurological basis (and binaural processing)
Auditory attention in regards to the cocktail party effect primarily occurs in the left hemisphere of the superior temporal gyrus, a non-primary region of auditory cortex; a fronto-parietal network involving the inferior frontal gyrus, superior parietal sulcus, and intraparietal sulcus also accounts for the acts of attention-shifting, speech processing, and attention control. Both the target stream (the more important information being attended to) and competing/interfering streams are processed in the same pathway within the left hemisphere, but fMRI scans show that target streams are treated with more attention than competing streams.
Furthermore, activity in the superior temporal gyrus (STG) toward the target stream is decreased/interfered with when competing stimuli streams (that typically hold significant value) arise. The "cocktail party effect" – the ability to detect significant stimuli in multi-talker situations – has also been labeled the "cocktail party problem", because the ability to selectively attend simultaneously interferes with the effectiveness of attention at a neurological level.
The cocktail party effect works best as a binaural effect, which requires hearing with both ears. People with only one functioning ear seem much more distracted by interfering noise than people with two typical ears. The benefit of using two ears may be partially related to the localization of sound sources. The auditory system is able to localize at least two sound sources and assign the correct characteristics to these sources simultaneously. As soon as the auditory system has localized a sound source, it can extract the signals of this sound source out of a mixture of interfering sound sources. However, much of this binaural benefit can be attributed to two other processes, better-ear listening and binaural unmasking. Better-ear listening is the process of exploiting the better of the two signal-to-noise ratios available at the ears. Binaural unmasking is a process that involves a combination of information from the two ears in order to extract signals from noise.
Early work
In the early 1950s much of the early attention research can be traced to problems faced by air traffic controllers. At that time, controllers received messages from pilots over loudspeakers in the control tower. Hearing the intermixed voices of many pilots over a single loudspeaker made the controller's task very difficult. The effect was first defined and named "the cocktail party problem" by Colin Cherry in 1953.
Cherry conducted attention experiments in which participants listened to two different messages from a single loudspeaker at the same time and tried to separate them; this was later termed a dichotic listening task. His work reveals that the ability to separate sounds from background noise is affected by many variables, such as the sex of the speaker, the direction from which the sound is coming, the pitch, and the rate of speech.
Cherry developed the shadowing task in order to further study how people selectively attend to one message amid other voices and noises. In a shadowing task participants wear a special headset that presents a different message to each ear. The participant is asked to repeat aloud the message (called shadowing) that is heard in a specified ear (called a channel). Cherry found that participants were able to detect their name from the unattended channel, the channel they were not shadowing. Later research using Cherry's shadowing task was done by Neville Moray in 1959. He was able to conclude that almost none of the rejected message is able to penetrate the block set up, except subjectively "important" messages.
More recent work
Selective attention shows up across all ages. Starting with infancy, babies begin to turn their heads toward a sound that is familiar to them, such as their parents' voices. This shows that infants selectively attend to specific stimuli in their environment. Reviews of selective attention indicate that infants favor "baby" talk over speech with an adult tone. This preference indicates that infants can recognize physical changes in the tone of speech. The accuracy in noticing these physical differences, like tone, amid background noise improves over time. Infants may simply ignore stimuli because something like their name, while familiar, holds no higher meaning to them at such a young age; research suggests that infants do not understand that the noise being presented to them amidst distracting noise is their own name, and thus do not respond. The ability to filter out unattended stimuli reaches its prime in young adulthood. In reference to the cocktail party phenomenon, older adults have a harder time than younger adults focusing in on one conversation if competing stimuli, like "subjectively" important messages, make up the background noise.
Examples of messages that catch people's attention include personal names and taboo words. The ability to selectively attend to one's own name has been found in infants as young as 5 months of age and appears to be fully developed by 13 months. Along with multiple experts in the field, Anne Treisman states that people are permanently primed to detect personally significant words, like names, and theorizes that they may require less perceptual information than other words to trigger identification. Taboo words often contain sexually explicit material that cause an alert system in people that leads to decreased performance in shadowing tasks. Taboo words do not affect children in selective attention until they develop a strong vocabulary with an understanding of language.
Selective attention begins to waver as we get older. Older adults have longer latency periods in discriminating between conversation streams, typically attributed to the fact that general cognitive ability begins to decay with old age (as exemplified with memory, visual perception, higher order functioning, etc.).
Even more recently, modern neuroscience techniques are being applied to study the cocktail party problem. Some notable examples of researchers doing such work include Edward Chang, Nima Mesgarani, and Charles Schroeder using electrocorticography; Jonathan Simon, Mounya Elhilali, Adrian KC Lee, Shihab Shamma, Barbara Shinn-Cunningham, Daniel Baldauf, and Jyrki Ahveninen using magnetoencephalography; Jyrki Ahveninen, Edmund Lalor, and Barbara Shinn-Cunningham using electroencephalography; and Jyrki Ahveninen and Lee M. Miller using functional magnetic resonance imaging.
Models of attention
Not all the information presented to us can be processed. In theory, the selection of what to pay attention to can be random or nonrandom. For example, when driving, drivers are able to focus on the traffic lights rather than on other stimuli present in the scene. In such cases it is mandatory to select which portion of presented stimuli is important. A basic question in psychology is when this selection occurs. This issue has developed into the early versus late selection controversy. The basis for this controversy can be found in the Cherry dichotic listening experiments. Participants were able to notice physical changes, like pitch or change in gender of the speaker, and stimuli, like their own name, in the unattended channel. This brought about the question of whether the meaning, semantics, of the unattended message was processed before selection. In an early selection attention model very little information is processed before selection occurs. In late selection attention models more information, like semantics, is processed before selection occurs.
Broadbent
The earliest work in exploring mechanisms of early selective attention was performed by Donald Broadbent, who proposed a theory that came to be known as the filter model. This model was established using the dichotic listening task. His research showed that most participants were accurate in recalling information that they actively attended to, but were far less accurate in recalling information that they had not attended to. This led Broadbent to the conclusion that there must be a "filter" mechanism in the brain that could block out information that was not selectively attended to. The filter model was hypothesized to work in the following way: as information enters the brain through sensory organs (in this case, the ears) it is stored in sensory memory, a buffer memory system that hosts an incoming stream of information long enough for us to pay attention to it. Before information is processed further, the filter mechanism allows only attended information to pass through. The selected attention is then passed into working memory, the set of mechanisms that underlies short-term memory and communicates with long-term memory. In this model, auditory information can be selectively attended to on the basis of its physical characteristics, such as location and volume. Others suggest that information can be attended to on the basis of Gestalt features, including continuity and closure. For Broadbent, this explained the mechanism by which people can choose to attend to only one source of information at a time while excluding others. However, Broadbent's model failed to account for the observation that words of semantic importance, for example the individual's own name, can be instantly attended to despite having been in an unattended channel.
Shortly after Broadbent's experiments, Oxford undergraduates Gray and Wedderburn repeated his dichotic listening tasks, altered with monosyllabic words that could form meaningful phrases, except that the words were divided across ears. For example, the words, "Dear, one, Jane," were sometimes presented in sequence to the right ear, while the words, "three, Aunt, six," were presented in a simultaneous, competing sequence to the left ear. Participants were more likely to remember, "Dear Aunt Jane," than to remember the numbers; they were also more likely to remember the words in the phrase order than to remember the numbers in the order they were presented. This finding goes against Broadbent's theory of complete filtration because the filter mechanism would not have time to switch between channels. This suggests that meaning may be processed first.
Treisman
In a later addition to this existing theory of selective attention, Anne Treisman developed the attenuation model. In this model, information, when processed through a filter mechanism, is not completely blocked out as Broadbent might suggest. Instead, the information is weakened (attenuated), allowing it to pass through all stages of processing at an unconscious level. Treisman also suggested a threshold mechanism whereby some words, on the basis of semantic importance, may grab one's attention from the unattended stream. One's own name, according to Treisman, has a low threshold value (i.e. it has a high level of meaning) and thus is recognized more easily. The same principle applies to words like fire, directing our attention to situations that may immediately require it. The only way this can happen, Treisman argued, is if information was being processed continuously in the unattended stream.
Deutsch and Deutsch
Diana Deutsch, best known for her work in music perception and auditory illusions, has also made important contributions to models of attention. In order to explain in more detail how words can be attended to on the basis of semantic importance, Deutsch & Deutsch and Norman proposed a model of attention which includes a second selection mechanism based on meaning. In what came to be known as the Deutsch-Norman model, information in the unattended stream is not processed all the way into working memory, as Treisman's model would imply. Instead, information on the unattended stream is passed through a secondary filter after pattern recognition. If the unattended information is recognized and deemed unimportant by the secondary filter, it is prevented from entering working memory. In this way, only immediately important information from the unattended channel can come to awareness.
Kahneman
Daniel Kahneman also proposed a model of attention, but it differs from previous models in that he describes attention not in terms of selection, but in terms of capacity. For Kahneman, attention is a resource to be distributed among various stimuli, a proposition which has received some support. This model describes not when attention is focused, but how it is focused. According to Kahneman, attention is generally determined by arousal; a general state of physiological activity. The Yerkes-Dodson law predicts that arousal will be optimal at moderate levels - performance will be poor when one is over- or under-aroused. Of particular relevance, Narayan et al. discovered a sharp decline in the ability to discriminate between auditory stimuli when background noises were too numerous and complex - this is evidence of the negative effect of overarousal on attention. Thus, arousal determines our available capacity for attention. Then, an allocation policy acts to distribute our available attention among a variety of possible activities. Those deemed most important by the allocation policy will have the most attention given to them. The allocation policy is affected by enduring dispositions (automatic influences on attention) and momentary intentions (a conscious decision to attend to something). Momentary intentions requiring a focused direction of attention rely on substantially more attention resources than enduring dispositions. Additionally, there is an ongoing evaluation of the particular demands of certain activities on attention capacity. That is to say, activities that are particularly taxing on attention resources will lower attention capacity and will influence the allocation policy - in this case, if an activity is too draining on capacity, the allocation policy will likely cease directing resources to it and instead focus on less taxing tasks. Kahneman's model explains the cocktail party phenomenon in that momentary intentions might allow one to expressly focus on a particular auditory stimulus, but that enduring dispositions (which can include new events, and perhaps words of particular semantic importance) can capture our attention. It is important to note that Kahneman's model doesn't necessarily contradict selection models, and thus can be used to supplement them.
Visual correlates
Some research has demonstrated that the cocktail party effect may not be simply an auditory phenomenon, and that relevant effects can be obtained when testing visual information as well. For example, Shapiro et al. were able to demonstrate an "own name effect" with visual tasks, where subjects were able to easily recognize their own names when presented as unattended stimuli. They adopted a position in line with late selection models of attention such as the Treisman or Deutsch-Norman models, suggesting that early selection would not account for such a phenomenon. The mechanisms by which this effect might occur were left unexplained.
Effect in animals
Animals that communicate in choruses such as frogs, insects, songbirds and other animals that communicate acoustically can experience the cocktail party effect as multiple signals or calls occur concurrently. Similar to their human counterparts, acoustic mediation allows animals to listen for what they need to within their environments. For Bank swallows, cliff swallows, and king penguins, acoustic mediation allows for parent/offspring recognition in noisy environments. Amphibians also demonstrate this effect as evidenced in frogs; female frogs can listen for and differentiate male mating calls, while males can mediate other males' aggression calls. There are two leading theories as to why acoustic signaling evolved among different species. Receiver psychology holds that the development of acoustic signaling can be traced back to the nervous system and the processing strategies the nervous system uses. Specifically, how the physiology of auditory scene analysis affects how a species interprets and gains meaning from sound. Communication Network Theory states that animals can gain information by eavesdropping on other signals between others of their species. This is true especially among songbirds.
Hearables for the cocktail party effect
Hearable devices like noise-canceling headphones have been designed to address the cocktail party problem. These type of devices could provide wearers with a degree of control over the sound sources around them.
Deep learning headphone systems like target speech hearing have been proposed to give wearers the ability to hear a target person in a crowded room with multiple speakers and background noise. This technology uses real-time neural networks to learn the voice characteristics of an enrolled target speaker, which is later used to focus on their speech while suppressing other speakers and noise. Semantic hearing headsets also use neural networks to enable wearers to hear specific sounds, such as birds tweeting or alarms ringing, based on their semantic description, while suppressing other ambient sounds in the environment. Real-time neural networks have also been used to create programmable sound bubbles on headsets, allowing all speakers within the bubble to be audible while suppressing speakers and noise outside the bubble.
These devices could benefit individuals with hearing loss, sensory processing disorders and misophonia as well as people who require focused listening for their job in health-care and military, or for factory or construction workers.
See also
References
Acoustics
Hearing
Attention
Audiology
Psychological effects | Cocktail party effect | Physics | 3,627 |
50,414,321 | https://en.wikipedia.org/wiki/U%20Monocerotis | U Monocerotis (U Mon) is a pulsating variable star and spectroscopic binary in the constellation Monoceros. The primary star is an RV Tauri variable, a cool luminous post-AGB star evolving into a white dwarf.
History
U Mon was reported to be variable in 1918 by the renown German astronomer Ernst Hartwig. It was then included by Shapley in his list of Cepheid variables. In the 1950s a series of papers established the fundamental observational parameters of the star, its period, brightness range, colour changes, and spectral variation.
In 1970, U Mon was discovered to have a large infrared excess. The double-peaked spectral energy distribution and polarization are strongly indicative of a dust shell around the star.
Visibility
U Mon can often be seen with the naked eye between Sirius and Procyon, but drops below naked eye visibility at deep minima. It lies about two degrees west of α Mon, at fourth magnitude the brightest star in Monoceros. At its brightest U Mon can reach magnitude 5.45. At a shallow minimum it drops to about magnitude 6.0, but at its deepest minima it is below magnitude 7.5. The period is given as 92.23 days, although this varies slightly from cycle to cycle. The brightness of the main pulsations varies over a long secondary period. This takes about 2,500 days, more than twice the length of the secondary period in any other RV Tauri variable.
System
U Mon is a binary system with a dusty ring surrounding both stars. The companion cannot be observed directly or in the spectrum. Its existence is inferred by radial velocity changes as it orbits every 2,597 days. This is approximately the same time as the long secondary period that modulates the brightness variations. One model for these longterm variations is a periodic eclipse by a circumbinary dust disc.
Properties
The exact properties of U Mon are uncertain. It has a measured parallax, but with considerable uncertainty. The properties can be inferred by other methods such as spectral line profiles and atmospheric modelling, but these methods are also uncertain for unusual stars like U Mon. RV Tauri stars have been shown to follow a period-luminosity relationship, and this can be used to confirm the luminosity and distance.
RV Tauri stars have low masses, although U Mon has been calculated to have one of the highest known masses for the class at about . Despite the low masses, they are highly extended cool stars of high luminosity. U Mon has a luminosity of , although this is both variable and highly uncertain. The spectral luminosity class is supergiant, indicating the rarefied nature of its atmosphere and low surface gravity. The surface gravity varies during the pulsations, dropping to extremely low values as the star passes through its largest size. The temperature varies by about 1,000 K, being hottest when the star is rising towards a maximum. Integrated radial velocities indicate that during the largest pulsations, the location of the reversing layer in the atmosphere moves by nearly 90% of the average stellar radius.
U Mon is a metal-poor star, as expected for a low-mass post-AGB object. It shows some enhancement of Carbon, but only to about 80% of the oxygen abundance. There is no suggestion of s-process elements being over-abundant. This is consistent with first dredge-up abundances, suggesting that most RV Tauri stars were not massive enough to experience a third dredge-up.
U Mon is surrounded by a dusty circumstellar disc, a common feature of RV Tauri variables. It is likely to be created by interaction with a binary companion.
Evolution
U Mon is likely a post-Asymptotic Giant Branch (AGB) star, a low to intermediate mass star which is in the end stages of its life just prior to the expulsion of a planetary nebula and contraction to a white dwarf. RV Tauri variables give an insight into the lives and deaths of stars like the Sun. Evolution models show it takes about 10 billion years for a 1 solar mass () star to reach the Asymptotic Giant Branch.
References
Monoceros
RV Tauri variables
G-type supergiants
K-type supergiants
F-type supergiants
Monocerotis, U
59693
Durchmusterung objects
IRAS catalogue objects
J07304746-0946366
036521 | U Monocerotis | Astronomy | 924 |
47,222,588 | https://en.wikipedia.org/wiki/Molecular%20vapor%20deposition | Molecular vapor deposition is the gas-phase reaction between surface reactive chemicals and an appropriately receptive surface.
Often bi-functional silanes are used in which one termination of the molecule is reactive. For example, a functional chlorosilane (R-Si-Cl3) can react with surface hydroxyl groups (-OH) resulting a radicalized (R) deposition on the surface.
The advantage of a gas phase reaction over a comparable liquid phase process is the control of moisture from the ambient environment, which often results in cross polymerization of the silane leading to particulates on the treated surface. Often a heated sub-atmospheric vacuum chamber is used to allow precise control of the reactants and water content. Additionally the gas phase process allows for easy treatment of complex parts since the coverage of the reactant is generally diffusion limited. Microelectromechanical Systems (MEMS) sensors often use molecular vapor deposition as a technique to address stiction and other parasitic issues relative to surface-to-surface interactions.
References
Chemical vapor deposition
Industrial processes
Thin film deposition | Molecular vapor deposition | Chemistry,Materials_science,Mathematics | 219 |
11,740,016 | https://en.wikipedia.org/wiki/HD%202039 | HD 2039 is a yellow dwarf or yellow subgiant star in the constellation Phoenix. The star is not visible to the naked eye, and lies 280 light years away from the Sun. HD 2039 is a relatively stable star, and an exoplanet at least three times the mass of the planet Jupiter has been discovered in its orbit; this exoplanet, known as HD 2039 b, was the 100th exoplanet to be discovered.
Nomenclature
The designation HD 2039 from the Henry Draper Catalogue. The catalogue, which was published between 1918 and 1924, was based on the work of Annie Jump Cannon and her team between 1911 and 1915. HD 2039 does not have a common, colloquial name that is characteristic of stars like Sirius, Procyon, and Aldebaran.
Characteristics
HD 2039 is a stable G-type star, meaning it shines with white light that can be seen in the Sun. HD 2039 exhibits a radius approximately 40 percent larger than the Sun's. The star is slightly hotter than the Sun; while HD 2039 has a temperature of 5935 K, the Sun's surface temperature lies nearly 200 kelvins lower at 5778 K. HD 2039 is unusually metal-rich, which has attracted the attention of astrophysicists.
Distance and visibility
The star's magnitude as observed from Earth is 9; this signifies that the body is not visible with the naked eye, but can be seen with a telescope. HD 2039 lies roughly 280 light years from the Sun, which is about as far from the Sun as the second brightest star in the night sky, Canopus.
Planetary system
In 2002, a planet was found by the Anglo-Australian Planet Search team to be orbiting the star in a very eccentric orbit. It has a minimum mass more than four times that of Jupiter and has an orbital period of over three years. The planet orbits its star at a distance of approximately two AU away; the planet Earth, in comparison, orbits at a distance of one AU away from the Sun. HD 2039 b's discovery was reported quietly; no press release was provided by the observatory that discovered the star's planet, and no formal announcement of the planet's existence was made. The entity was the 100th exoplanet to have been verified by the scientific community.
See also
List of extrasolar planets
References
External links
The Extrasolar Planets Encyclopaedia: HD 2039
G-type main-sequence stars
G-type subgiants
002039
001931
Phoenix (constellation)
Planetary systems with one confirmed planet
Durchmusterung objects | HD 2039 | Astronomy | 539 |
37,227,345 | https://en.wikipedia.org/wiki/10%20Lacertae | 10 Lacertae (10 Lac) is a star in the constellation Lacerta. With an apparent magnitude of 4.9, it is located around distant in the small Lacerta OB1 association. It is a hot blue main-sequence star of spectral type O9V, a massive star that is currently fusing its core hydrogen. It is a suspected Beta Cephei variable star.
It was one of the first O-type stars (along with S Monocerotis) to be defined as an anchor point for the MKK spectral classification; since the early twentieth century it has served as such a point. Specifically, the star is representative of O9V stars, meaning relatively cool O-type stars on the main-sequence.
It is the star with the smallest angular diameter measured by the CHARA array, at .
10 Lacertae has an 8th magnitude companion about one arc-minute away.
References
Lacerta
O-type main-sequence stars
Lacertae, 10
8622
111841
214680
BD+38 4826 | 10 Lacertae | Astronomy | 215 |
39,491,428 | https://en.wikipedia.org/wiki/International%20Highrise%20Award | The International Highrise Award () is an international award in architectural design. The award is bestowed to "a structure that combines exemplary sustainability, external shape and internal spatial quality, not to mention social aspects, to create a model design."
Initiated in 2003 by the City of Frankfurt, German Architecture Museum and DekaBank it is granted in Frankfurt am Main every two years. The prize, a statuette by artist Thomas Demand and EUR 50,000 is awarded to the planners and developers jointly.
Recipient 2022: Quay Quarter Tower, Sydney
Recipient 2024: CapitaSpring, Singapore
Recipients
Bibliography
Michaela Busenkell (Hrsg.), Peter Cachola Schmal (Hrsg.): Best Highrises 2012/2013: Internationaler Hochhauspreis / The International Highrise Award 2012. Katalog zur Ausstellung im Deutschen Architekturmuseum Frankfurt am Main vom 17. November 2012 bis 13. Januar 2013. Edition Detail, München 2012, .
References
External links
Offizielle Seite zum Internationalen Hochhauspreis
Internationaler Hochhaus Preis - DekaBank (Preis-Sponsor und Mitbegründer)
2003 establishments in Germany
Architecture awards
Awards established in 2003 | International Highrise Award | Engineering | 259 |
50,408 | https://en.wikipedia.org/wiki/Computer%20engineering | Computer engineering (CoE or CpE) is a branch of electrical engineering that integrates several fields of electrical engineering, electronics engineering and computer science required to develop computer hardware and software. Computer engineering is referred to as Electrical and Computer engineering OR Computer Science and Engineering at some universities
Computer engineers require training in electrical engineering, electronic engineering, physics, computer science, hardware-software integration, software design, and software engineering. It uses the techniques and principles of electrical engineering and computer science, and can encompass areas such as electromagnetism, artificial intelligence (AI), robotics, computer networks, computer architecture and operating systems. Computer engineers are involved in many hardware and software aspects of computing, from the design of individual microcontrollers, microprocessors, personal computers, and supercomputers, to circuit design. This field of engineering not only focuses on how computer systems themselves work, but also on how to integrate them into the larger picture. Robotics are one of the applications of computer engineering.
Computer engineering usually deals with areas including writing software and firmware for embedded microcontrollers, designing VLSI chips, analog sensors, mixed signal circuit boards, Thermodynamics and Control systems. Computer engineers are also suited for robotics research, which relies heavily on using digital systems to control and monitor electrical systems like motors, communications, and sensors.
In many institutions of higher learning, computer engineering students are allowed to choose areas of in-depth study in their junior and senior years because the full breadth of knowledge used in the design and application of computers is beyond the scope of an undergraduate degree. Other institutions may require engineering students to complete one or two years of general engineering before declaring computer engineering as their primary focus.
History
Computer engineering began in 1939 when John Vincent Atanasoff and Clifford Berry began developing the world's first electronic digital computer through physics, mathematics, and electrical engineering. John Vincent Atanasoff was once a physics and mathematics teacher for Iowa State University and Clifford Berry a former graduate under electrical engineering and physics. Together, they created the Atanasoff-Berry computer, also known as the ABC which took five years to complete.
While the original ABC was dismantled and discarded in the 1940s, a tribute was made to the late inventors; a replica of the ABC was made in 1997, where it took a team of researchers and engineers four years and $350,000 to build.
The modern personal computer emerged in the 1970s, after several breakthroughs in semiconductor technology. These include the first working transistor by William Shockley, John Bardeen and Walter Brattain at Bell Labs in 1947, in 1955, silicon dioxide surface passivation by Carl Frosch and Lincoln Derick, the first planar silicon dioxide transistors by Frosch and Derick in 1957, planar process by Jean Hoerni, the monolithic integrated circuit chip by Robert Noyce at Fairchild Semiconductor in 1959, the metal–oxide–semiconductor field-effect transistor (MOSFET, or MOS transistor) demonstrated by a team at Bell Labs in 1960 and the single-chip microprocessor (Intel 4004) by Federico Faggin, Marcian Hoff, Masatoshi Shima and Stanley Mazor at Intel in 1971.
History of computer engineering education
The first computer engineering degree program in the United States was established in 1971 at Case Western Reserve University in Cleveland, Ohio. , there were 250 ABET-accredited computer engineering programs in the U.S. In Europe, accreditation of computer engineering schools is done by a variety of agencies as part of the EQANIE network. Due to increasing job requirements for engineers who can concurrently design hardware, software, firmware, and manage all forms of computer systems used in industry, some tertiary institutions around the world offer a bachelor's degree generally called computer engineering. Both computer engineering and electronic engineering programs include analog and digital circuit design in their curriculum. As with most engineering disciplines, having a sound knowledge of mathematics and science is necessary for computer engineers.
Education
Computer engineering is referred to as computer science and engineering at some universities. Most entry-level computer engineering jobs require at least a bachelor's degree in computer engineering, electrical engineering or computer science. Typically one must learn an array of mathematics such as calculus, linear algebra and differential equations, along with computer science. Degrees in electronic or electric engineering also suffice due to the similarity of the two fields. Because hardware engineers commonly work with computer software systems, a strong background in computer programming is necessary. According to BLS, "a computer engineering major is similar to electrical engineering but with some computer science courses added to the curriculum". Some large firms or specialized jobs require a master's degree.
It is also important for computer engineers to keep up with rapid advances in technology. Therefore, many continue learning throughout their careers. This can be helpful, especially when it comes to learning new skills or improving existing ones. For example, as the relative cost of fixing a bug increases the further along it is in the software development cycle, there can be greater cost savings attributed to developing and testing for quality code as soon as possible in the process, particularly before release.
Professions
A person with a profession in computer engineering is called a computer engineer.
Applications and practice
There are two major focuses in computer engineering: hardware and software.
Computer hardware engineering
According to the BLS, Job Outlook employment for computer hardware engineers, the expected ten-year growth from 2019 to 2029 for computer hardware engineering was an estimated 2% and a total of 71,100 jobs. ("Slower than average" in their own words when compared to other occupations)". This is a decrease from the 2014 to 2024 BLS computer hardware engineering estimate of 3% and a total of 77,700 jobs; "and is down from 7% for the 2012 to 2022 BLS estimate and is further down from 9% in the BLS 2010 to 2020 estimate." Today, computer hardware is somewhat equal to electronic and computer engineering (ECE) and has been divided into many subcategories, the most significant being embedded system design.
Computer software engineering
According to the U.S. Bureau of Labor Statistics (BLS), "computer applications software engineers and computer systems software engineers are projected to be among the faster than average growing occupations" The expected ten-year growth for computer software engineering was an estimated seventeen percent and there was a total of 1,114,000 jobs that same year. This is down from the 2012 to 2022 BLS estimate of 22% for software developers. And, further down from the 30% 2010 to 2020 BLS estimate. In addition, growing concerns over cybersecurity add up to put computer software engineering high above the average rate of increase for all fields. However, some of the work will be outsourced in foreign countries. Due to this, job growth will not be as fast as during the last decade, as jobs that would have gone to computer software engineers in the United States would instead go to computer software engineers in countries such as India. In addition, the BLS Job Outlook for Computer Programmers, 2014–24 has an −8% (a decline, in their words), then a Job Outlook, 2019-29 of -9% (Decline), then a 10% decline for 2021-2031 and now an 11% decline for 2022-2032 for those who program computers (i.e. embedded systems) who are not computer application developers. Furthermore, women in software fields has been declining over the years even faster than other engineering fields.
Computer engineering licensing and practice
Computer engineering is generally practiced within larger product development firms, and such practice may not be subject to licensing. However, independent consultants who advertise computer engineering, just like any form of engineering, may be subject to state laws which restrict professional engineer practice to only those who have received the appropriate License. The National Council of Examiners for Engineering and Surveying (NCEES) first offered a Principles and Practice of Engineering Examination for computer engineering in 2003.
Specialty areas
There are many specialty areas in the field of computer engineering.
Processor design
Processor design process involves choosing an instruction set and a certain execution paradigm (e.g. VLIW or RISC) and results in a microarchitecture, which might be described in e.g. VHDL or Verilog. CPU design is divided into design of the following components: datapaths (such as ALUs and pipelines), control unit: logic which controls the datapaths, memory components such as register files, caches, clock circuitry such as clock drivers, PLLs, clock distribution networks, pad transceiver circuitry, logic gate cell library which is used to implement the logic.
Coding, cryptography, and information protection
Computer engineers work in coding, applied cryptography, and information protection to develop new methods for protecting various information, such as digital images and music, fragmentation, copyright infringement and other forms of tampering by, for example, digital watermarking.
Communications and wireless networks
Those focusing on communications and wireless networks, work advancements in telecommunications systems and networks (especially wireless networks), modulation and error-control coding, and information theory. High-speed network design, interference suppression and modulation, design, and analysis of fault-tolerant system, and storage and transmission schemes are all a part of this specialty.
Compilers and operating systems
This specialty focuses on compilers and operating systems design and development. Engineers in this field develop new operating system architecture, program analysis techniques, and new techniques to assure quality. Examples of work in this field include post-link-time code transformation algorithm development and new operating system development.
Computational science and engineering
Computational science and engineering is a relatively new discipline. According to the Sloan Career Cornerstone Center, individuals working in this area, "computational methods are applied to formulate and solve complex mathematical problems in engineering and the physical and the social sciences. Examples include aircraft design, the plasma processing of nanometer features on semiconductor wafers, VLSI circuit design, radar detection systems, ion transport through biological channels, and much more".
Computer networks, mobile computing, and distributed systems
In this specialty, engineers build integrated environments for computing, communications, and information access. Examples include shared-channel wireless networks, adaptive resource management in various systems, and improving the quality of service in mobile and ATM environments. Some other examples include work on wireless network systems and fast Ethernet cluster wired systems.
Computer systems: architecture, parallel processing, and dependability
Engineers working in computer systems work on research projects that allow for reliable, secure, and high-performance computer systems. Projects such as designing processors for multithreading and parallel processing are included in this field. Other examples of work in this field include the development of new theories, algorithms, and other tools that add performance to computer systems.
Computer architecture includes CPU design, cache hierarchy layout, memory organization, and load balancing.
Computer vision and robotics
In this specialty, computer engineers focus on developing visual sensing technology to sense an environment, representation of an environment, and manipulation of the environment. The gathered three-dimensional information is then implemented to perform a variety of tasks. These include improved human modeling, image communication, and human-computer interfaces, as well as devices such as special-purpose cameras with versatile vision sensors.
Embedded systems
Individuals working in this area design technology for enhancing the speed, reliability, and performance of systems. Embedded systems are found in many devices from a small FM radio to the space shuttle. According to the Sloan Cornerstone Career Center, ongoing developments in embedded systems include "automated vehicles and equipment to conduct search and rescue, automated transportation systems, and human-robot coordination to repair equipment in space." , computer embedded systems specializations include system-on-chip design, the architecture of edge computing and the Internet of things.
Integrated circuits, VLSI design, testing and CAD
This specialty of computer engineering requires adequate knowledge of electronics and electrical systems. Engineers working in this area work on enhancing the speed, reliability, and energy efficiency of next-generation very-large-scale integrated (VLSI) circuits and microsystems. An example of this specialty is work done on reducing the power consumption of VLSI algorithms and architecture.
Signal, image and speech processing
Computer engineers in this area develop improvements in human–computer interaction, including speech recognition and synthesis, medical and scientific imaging, or communications systems. Other work in this area includes computer vision development such as recognition of human facial features.
Quantum computing
This area integrates the quantum behaviour of small particles such as superposition, interference and entanglement, with classical computers to solve complex problems and formulate algorithms much more efficiently. Individuals focus on fields like Quantum cryptography, physical simulations and quantum algorithms.
Benefits of Engineering in Society
An accessible avenue for obtaining information and opportunities in technology, especially for young students, is through digital platforms, enabling learning, exploration, and potential income generation at minimal cost and in regional languages, none of which would be possible without engineers. Computer engineering is important in the changes involved in industry 4.0, with engineers responsible for designing and optimizing the technology that surrounds our lives, from big data to AI. Their work not only facilitates global connections and knowledge access, but also plays a pivotal role in shaping our future, as technology continues to evolve rapidly, leading to a growing demand for skilled computer engineers. Engineering contributes to improving society by creating devices and structures impacting various aspects of our lives, from technology to infrastructure. Engineers also address challenges such as environmental protection and sustainable development, while developing medical treatments. As of 2016, the median annual wage across all BLS engineering categories was over $91,000. Some were much higher, with engineers working for petroleum companies at the top (over $128,000). Other top jobs include: Computer Hardware Engineer – $115,080, Aerospace Engineer – $109,650, Nuclear Engineer – $102,220.
See also
Related fields
Associations
IEEE Computer Society
Association for Computing Machinery
References
External links
Electrical and computer engineering
Engineering disciplines | Computer engineering | Technology,Engineering | 2,856 |
23,572,924 | https://en.wikipedia.org/wiki/C10H12N2O5 | {{DISPLAYTITLE:C10H12N2O5}}
The molecular formula C10H12N2O5 (molar mass: 240.21 g/mol, exact mass: 240.0746 u) may refer to:
Dinoseb, an herbicide also known as 6-sec-butyl-2,4-dinitrophenol
Dinoterb, an herbicide | C10H12N2O5 | Chemistry | 88 |
4,254,743 | https://en.wikipedia.org/wiki/Chorography | Chorography (from χῶρος khōros, "place" and γράφειν graphein, "to write") is the art of describing or mapping a region or district, and by extension such a description or map. This term derives from the writings of the ancient geographer Pomponius Mela and Ptolemy, where it meant the geographical description of regions. However, its resonances of meaning have varied at different times. Richard Helgerson states that "chorography defines itself by opposition to chronicle. It is the genre devoted to place, and chronicle is the genre devoted to time". Darrell Rohl prefers a broad definition of "the representation of space or place".
Ptolemy's definition
In his text of the Geographia (2nd century CE), Ptolemy defined geography as the study of the entire world, but chorography as the study of its smaller parts—provinces, regions, cities, or ports. Its goal was "an impression of a part, as when one makes an image of just an ear or an eye"; and it dealt with "the qualities rather than the quantities of the things that it sets down". Ptolemy implied that it was a graphic technique, comprising the making of views (not simply maps), since he claimed that it required the skills of a draftsman or landscape artist, rather than the more technical skills of recording "proportional placements". Ptolemy's most recent English translators, however, render the term as "regional cartography".
Renaissance revival
Ptolemy's text was rediscovered in the west at the beginning of the fifteenth century, and the term "chorography" was revived by humanist scholars. John Dee in 1570 regarded the practice as "an underling, and a twig of Geographie", by which the "plat" [plan or drawing] of a particular place would be exhibited to the eye.
The term also came to be used, however, for written descriptions of regions. These regions were extensively visited by the writer, who then combined local topographical description, summaries of the historical sources, and local knowledge and stories, into a text. The most influential example (at least in Britain) was probably William Camden's Britannia (first edition 1586), which described itself on its title page as a Chorographica descriptio. William Harrison in 1587 similarly described his own "Description of Britaine" as an exercise in chorography, distinguishing it from the historical/chronological text of Holinshed's Chronicles (to which the "Description" formed an introductory section). Peter Heylin in 1652 defined chorography as "the exact description of some Kingdom, Countrey, or particular Province of the same", and gave as examples Pausanias's Description of Greece (2nd century AD); Camden's Britannia (1586); Lodovico Guicciardini's Descrittione di tutti i Paesi Bassi (1567) (on the Low Countries); and Leandro Alberti's Descrizione d'Italia (1550).
Camden's Britannia was predominantly concerned with the history and antiquities of Britain, and, probably as a result, the term chorography in English came to be particularly associated with antiquarian texts. William Lambarde, John Stow, John Hooker, Michael Drayton, Tristram Risdon, John Aubrey and many others used it in this way, arising from a gentlemanly topophilia and a sense of service to one's county or city, until it was eventually often applied to the genre of county history. A late example was William Grey's Chorographia (1649), a survey of the antiquities of the city of Newcastle upon Tyne. Even before Camden's work appeared, Andrew Melville in 1574 had referred to chorography and chronology as the "twa lights" [two lights] of history.
However, the term also continued to be used for maps and map-making, particularly of sub-national or county areas. William Camden praised the county mapmakers Christopher Saxton and John Norden as "most skilfull (sic) Chorographers"; and Robert Plot in 1677 and Christopher Packe in 1743 both referred to their county maps as chorographies.
By the beginning of the eighteenth century the term had largely fallen out of use in all these contexts, being superseded for most purposes by either "topography" or "cartography". Samuel Johnson in his Dictionary (1755) made a distinction between geography, chorography and topography, arguing that geography dealt with large areas, topography with small areas, but chorography with intermediary areas, being "less in its object than geography, and greater than topography". In practice, however, the term is only rarely found in English by this date.
Modern usages
In more technical geographical literature, the term had been abandoned as city views and city maps became more and more sophisticated and demanded a set of skills that required not only skilled draftsmanship but also some knowledge of scientific surveying. However, its use was revived for a second time in the late nineteenth century by the geographer Ferdinand von Richthofen. He regarded chorography as a specialization within geography, comprising the description through field observation of the particular traits of a given area.
The term is also now widely used by historians and literary scholars to refer to the early modern genre of topographical and antiquarian literature.
See also
Local history
Antiquarianism
Cartography
Khôra
Chorology
English county histories
Regional geography
References
Bibliography
Area studies
Cartography
Fields of history
History of geography
Humanities
Regional geography
Surveying
Topography techniques | Chorography | Engineering | 1,172 |
38,882,738 | https://en.wikipedia.org/wiki/Malga%C3%A7%20Raid | The Malgaç Raid, was a raid conducted by Yörük Ali Efe and his men on 16 June 1919. The target of the raid was the Malgaç railway bridge, which was used by the Greeks to transport military equipment to Nazilli and beyond. It was one of the first organized civil resistance attacks against the invading Greek forces in western Anatolia.
Prelude
The bridge was part of the Izmir-Aydın railway, which was the first railway built in the Ottoman Empire. The Malgaç bridge was located between Sultanhisar and Atça, built above the Malgaç stream.
Raid
The bridge was guarded by 20 heavily armed Greek soldiers, supported with machine guns. In the night of 15–16 June, the Turks advanced from Donduran and crossed the Büyük Menderes River with rafts at 02:00 am. During the crossing they were divided into two groups, each group contained 30 men. When they finally reached the Malgaç bridge, they surrounded it by advancing in the cornfields. Simultaneously, some of the men climbed on the telephone poles and cut off the phone lines to prevent the calling of Greek reinforcements. They attacked the bridge from three sides, surprising the Greek guards and killing all of them. The bridge was destroyed by placing dynamite at the bridge piers. Woken up by the explosion and loud gunfire, Greek soldiers from the nearby headquarter tried to reach for help but they were hold off. After inflicting some casualties on the reinforcements, the Turkish forces retreated. The attack lasted several hours and the Greek troops had suffered over 20 killed and the Turks had only one wounded.
Result
The Turks had captured some weapons and ammunition. As a result of the destruction of the bridge and the railway, the invading Greek forces could not use the railway to transport equipment on the Aydın-Nazilli route for a considerable time.
References
Sources
YORUK ALI EFE AND MALGAC SURPRISE ATTACK Sultanhisar Municipality
Çine Kuvayı Milliye Müzesi, Yaşar Aksoy, 06.07.2008 (Article about the Malgaç Raid)
Malgaç Baskını'nın 93. Yıldönümü (93rd anniversary of the Malgaç Raid) haberler.com
Battles of the Greco-Turkish War (1919–1922)
History of Aydın Province
Aidin Vilayet
1919 in the Ottoman Empire
1919 in Greece
Conflicts in 1919
Kuva-yi Milliye
June 1919
Battles in 1919
Bridge bombings
Attacks on railway systems
Bridge disasters in Asia
Bridge disasters caused by warfare
Military raids
Attacks on buildings and structures in Turkey
Attacks on buildings and structures in the 1910s | Malgaç Raid | Technology | 548 |
1,131,652 | https://en.wikipedia.org/wiki/No%20pain%2C%20no%20gain | No pain, no gain (or "No gain without pain") is a proverb, used since the 1980s as an exercise motto that promises greater value rewards for the price of hard and even painful work. Under this conception competitive professionals, such as athletes and artists, are required to endure pain (physical suffering) and stress (mental/emotional suffering) to achieve professional excellence. Medical experts agree that the proverb is mostly ineffective for exercise.
Exercise motto
It came into prominence after 1982 when actress Jane Fonda began to produce a series of aerobics workout videos. In these videos, Fonda would use "No pain, no gain" and "Feel the burn" as catchphrases for the concept of working out past the point of experiencing muscle aches.
It expresses the belief that solid large muscle is the result of training hard. Delayed onset muscle soreness is often used as a measure of the effectiveness of a workout.
In terms of the expression used for development, the discomfort caused may be beneficial in some instances while detrimental in others. Detrimental pain can include joint pain. Beneficial pain usually refers to that resulting from tearing microscopic muscle fibers, which will be rebuilt more densely, making a bigger muscle.
The expression has been adopted in a variety of sports and fitness activities, beginning in 1982 to present day.
David B. Morris wrote in The Scientist in 2005, "'No pain, no gain' is an American modern mini-narrative: it compresses the story of a protagonist who understands that the road to achievement runs only through hardship." The concept has been described as being a modern form of Puritanism.
Origin
The ancient Greek poet Hesiod (c. 750-650 BC) expresses this idea in Works and Days where he wrote:
The ancient Greek playwright Sophocles (5th Century BC) expresses this idea in the play Electra (line 945). This line is translated as: "nothing truly succeeds without pain", "nothing succeeds without toil", "there is no success without hard work", and "Without labour nothing prospers (well)."
A form of this expression is found in the beginning of the second century, written in The Ethics of the Fathers 5:23 (known in Hebrew as Pirkei Avot), which quotes Ben Hei Hei as saying, "According to the pain is the reward." This is interpreted to be a spiritual lesson; without the pain in doing what God commands, there is no spiritual gain.
In 1577 British poet Nicholas Breton wrote: "They must take pain that look for any gain."
One of the earliest attestations of the phrase comes from the poet Robert Herrick in his "Hesperides". In the 1650 edition, a two-line poem was added:
A version of the phrase was crafted by Benjamin Franklin, in his persona of Poor Richard (1734), to illustrate the axiom "God helps those who help themselves":
In the phrase, Franklin's central thesis was that everyone should exercise 45 minutes each day.
In 1853 R. C. Trench wrote in On Lessons in Proverbs iv: "For the most part they courageously accept the law of labour, No pains, no gains,—No sweat, no sweet, as the appointed law and condition of man's life."
In 1859 Samuel Smiles included “No pains no gains” in a list of proverbs about the secret to making money in Self-Help (book).
See also
Pain & Gain
Sports injury
What does not kill me, makes me stronger (quote by Nietzsche)
References
Aerobic exercise
Bodybuilding
English phrases
Mottos
Personal development | No pain, no gain | Biology | 745 |
51,085,842 | https://en.wikipedia.org/wiki/HD%20164595 | HD 164595 is a wide binary star system in the northern constellation of Hercules. The primary component of this pair hosts an orbiting exoplanet. The system is located at a distance of 92 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of 2.0 km/s. Although it has an absolute magnitude of +4.81, at that distance it is too faint to be viewed with the naked eye, having an apparent visual magnitude of 7.07. The brighter star can be found with binoculars or a small telescope less than a degree to the east-northeast of Xi Herculis. HD 164595 has a relatively large proper motion, traversing the celestial sphere at an angular rate of yr−1.
The spectrum of the primary, component A, presents as a G-type main-sequence star with a stellar classification of G2 V. It is considered an excellent solar twin candidate, although it has a lower logarithm of metallicity ratio, at −0.06 compared with 0.00, and a slightly younger age, at 4.5 versus 4.6 billion years. The estimated mass, radius, and luminosity of this star are all similar to the Sun, and the level of magnetic activity in the chromosphere is comparable to solar levels.
The secondary member, component B, is a magnitude 12.5 star at a projected separation of from the primary. It is a small red dwarf of spectral class M2.5 V. Periodic variations in the light curve of this star suggest a rotation period of 43.5 days.
Planetary system
HD 164595 has one known exoplanet, , which orbits HD 164595 A every 40 days. It was detected with the radial velocity technique with the SOPHIE echelle spectrograph. Since the inclination of the orbital plane is unknown, only a lower bound on the mass of the object can be determined. The exoplanet has a minimal mass equivalent of 16 Earths.
Signal observation and SETI
In 2016, HD 164595 briefly attracted media attention after it was reported that a possible SETI signal had been detected from the direction of the star in the previous year. The signal was only heard once and never confirmed by other telescopes, and is thought to have been due to terrestrial interference.
On 15 May 2015, a brief, single radio signal at 11 GHz (2.7 cm wavelength) was observed in the direction of HD 164595 by a team led by N. N. Bursov involving Claudio Maccone at the RATAN-600 radio observatory. The signal may have been caused by terrestrial radio-frequency interference or gravitational lensing from a more distant source. It was observed only once (for two seconds), by a single team, at a single telescope, giving it a Rio Scale score of 1 (insignificant) or 2 (low). Discussions in the media from 29 August 2016 onwards featured speculation that the signal could be caused by an isotropic beacon from a Type II civilization.
The senior astronomer of the SETI Institute, Seth Shostak, stated that confirmation by another telescope is required. Astronomer Nicholas Suntzeff of Texas A&M University stated that the signal is in a military frequency band, and that it could have been a satellite downlink, implying that some such systems may be kept secret and therefore would be unknown to SETI scientists.
SETI and METI studies followed with the Allen Telescope Array and the Boquete Optical SETI Observatory. Also, scientists at Berkeley SETI Research Center at the University of California, Berkeley observed HD 164595 using the Green Bank Telescope as part of the Breakthrough Listen program. No signal was detected at the position and frequency of the transient reported by the RATAN group.
The Special Astrophysical Observatory of the Russian Academy of Sciences has since released an official statement that the signal is of a "most probable terrestrial origin".
See also
Arecibo message, a three-minute-long message sent into space
HD 162826
Tabby's Star (KIC 8462852)
Wow! signal, possible alien radio signal
Footnotes
References
G-type main-sequence stars
M-type main-sequence stars
Solar analogs
Planetary systems with one confirmed planet
Binary stars
Hercules (constellation)
BD+29 3165
164595
088194
J18003890+2934188
Search for extraterrestrial intelligence
2016 in science | HD 164595 | Astronomy | 911 |
39,564,606 | https://en.wikipedia.org/wiki/Sophorolipid | A sophorolipid is a surface-active glycolipid compound that can be synthesized by a selected number of non-pathogenic yeast species. They are potential bio-surfactants due to their biodegradability and low eco-toxicity.
Structure and properties
Sophorolipids are glycolipids consisting of a hydrophobic fatty acid tail of 16 or 18 carbon atoms and a hydrophilic carbohydrate head sophorose, a glucose-derived di-saccharide with an unusual β-1,2 bond and can be acetylated on the 6′- and/or 6′′- positions. One terminal or sub terminal hydroxylated fatty acid is β-glycosidically linked to the sophorose module. The carboxylic end of this fatty acid is either free (acidic or open form) or internally esterified at the 4′′ or in some rare cases at the 6′- or 6′′-position (lactonic form). The physicochemical and biological properties of sophorolipids are significantly influenced by the distribution of the lactone vs. acidic forms produced in the fermentative broth. In general, lactone sophorolipids are more efficient in reducing surface tension and are better antimicrobial agents, whereas acidic sophorolipids display better foaming properties. Acetyl groups can also lower the hydrophilicity of sophorolipids and enhance their antiviral and cytokine stimulating effects.
Sophorolipids are produced by various non pathogenic yeast species such as Candida apicola, Rhodotorula bogoriensis, Wickerhamiella domercqiae, and Starmerella bombicola. Recent research has meant sophorolipids can be recovered during a fermentation using a gravity separator in a loop with the bioreactor, enabling the production of >770 g/L sophorolipid at a productivity 4.24 g/L/h, some of the highest values seen in a fermentation process Desirable properties of biosurfactants are biodegradability and low toxicity. Sophorolipids produced by several yeasts belonging to candida and the starmerella clade, and Rhamnolipid produced by Pseudomonas aeruginosa etc.
Besides biodegradability, low toxicity, and high production potential, sophorolipids have a high surface and interfacial activity. Sophorolipids are reported to lower surface tension (ST) of water from 72 to 30-35 mN/m and the interfacial tension (IT) water/hexadecane from 40 to 1 mN/m. In addition to this, sophorolipids are reported to function under wide ranges of temperatures, pressures and ionic strengths; and they also possess a number of other useful biological activities including Antimicrobial, virucidal, Anticancer, Immuno-modulatory properties.
Research
A detailed and comprehensive literature review on the various aspects of sophorolipids production (e.g. producing micro-organisms, bio-synthetic pathway, effect of medium components and other fermentation conditions and downstream process of sophorolipids is available in the published work of Van Bogaert et al. This work also discusses potential application of sophorolipids (and their derivatives) as well as the potential for genetic engineering strains to enhance sophorolipid yields. Researchers have focused on optimization of sophorolipid production in submerged fermentation, but some efforts have also investigated the possibility of sophorololipid production using solid state fermentation (SSF). The production process can be significantly impacted by the specific properties of the carbon and oil substrates used; and several inexpensive alternatives to more traditional substrates have been investigated. These potential substrates include: biodiesel by-product streams, waste frying oil, restaurant waste oil, industrial fatty acid residues, mango seed fat, and soybean dark oil. The use of most of these substrates have resulted in lower yields compared to traditional fermentation substrates.
Chemical modifications of sophorolipids, and polysophorolipids
To enhance the performance of surfactant properties of natural sophorolipids, chemical modification methods have been actively pursued. Recently, researchers demonstrated the possibility of applying sophorolipids as building blocks via ring-opening metathesis polymerization for a new type of polymers, known as polysophorolipids which show promising potentials in biomaterials applications.
References
Carbohydrate chemistry
Glycolipids | Sophorolipid | Chemistry | 974 |
53,299,610 | https://en.wikipedia.org/wiki/Tommy%20Gate | Tommy Gate is an American brand of hydraulic liftgate, or tail lift, manufactured by Woodbine Manufacturing Company. The company was formed in 1965 by Delbert "Bus" Brown and its production facility is located in Woodbine, Iowa.
History
Prior to founding Woodbine Manufacturing Company, Delbert Brown manufactured farming equipment under the name of Brown Manufacturing Company. After inventing what was then one of the first trenching machines, Brown Manufacturing Company was sold to Omaha Steel Works. Three years later, Brown founded Woodbine Manufacturing Company and launched the Tommy Gate brand.
Expansion
The Woodbine manufacturing facility was initially built in 1965 to occupy 70,000 square feet of production space. It expanded in 1980 to 90,000 square feet and once again in 2000 when it grew to 140,000 square feet. The most recent expansion, completed in 2011, grew the plant to an overall 200,000 square feet (including 40,000 square feet of warehouse space).
Products
Tommy Gate manufactures a variety of hydraulic liftgates for trucks and other vehicles. Their main product lines include:
Parallel-arm: Versatile and capable of handling heavy loads.
Rail-gate: Ideal for low-clearance items.
Tuckunder: Compact design for smaller vehicles.
They also offer specialized liftgates like dump-through, level-ride, and side-loader models. Tommy Gate focuses on durability, reliability, and ease of use, with options for customization like remote controls and platform extensions.
References
External links
Companies based in Iowa
Manufacturing companies based in Iowa
Logistics industry in the United States
Mechanical engineering
Hydraulics | Tommy Gate | Physics,Chemistry,Engineering | 319 |
151,925 | https://en.wikipedia.org/wiki/Del | Del, or nabla, is an operator used in mathematics (particularly in vector calculus) as a vector differential operator, usually represented by the nabla symbol ∇. When applied to a function defined on a one-dimensional domain, it denotes the standard derivative of the function as defined in calculus. When applied to a field (a function defined on a multi-dimensional domain), it may denote any one of three operations depending on the way it is applied: the gradient or (locally) steepest slope of a scalar field (or sometimes of a vector field, as in the Navier–Stokes equations); the divergence of a vector field; or the curl (rotation) of a vector field.
Del is a very convenient mathematical notation for those three operations (gradient, divergence, and curl) that makes many equations easier to write and remember. The del symbol (or nabla) can be formally defined as a vector operator whose components are the corresponding partial derivative operators. As a vector operator, it can act on scalar and vector fields in three different ways, giving rise to three different differential operations: first, it can act on scalar fields by a formal scalar multiplication—to give a vector field called the gradient; second, it can act on vector fields by a formal dot product—to give a scalar field called the divergence; and lastly, it can act on vector fields by a formal cross product—to give a vector field called the curl. These formal products do not necessarily commute with other operators or products. These three uses, detailed below, are summarized as:
Gradient:
Divergence:
Curl:
Definition
In the Cartesian coordinate system with coordinates and standard basis , del is a vector operator whose components are the partial derivative operators ; that is,
Where the expression in parentheses is a row vector. In three-dimensional Cartesian coordinate system with coordinates and standard basis or unit vectors of axes , del is written as
As a vector operator, del naturally acts on scalar fields via scalar multiplication, and naturally acts on vector fields via dot products and cross products.
More specifically, for any scalar field and any vector field , if one defines
then using the above definition of , one may write
and
and
Example:
Del can also be expressed in other coordinate systems, see for example del in cylindrical and spherical coordinates.
Notational uses
Del is used as a shorthand form to simplify many long mathematical expressions. It is most commonly used to simplify expressions for the gradient, divergence, curl, directional derivative, and Laplacian.
Gradient
The vector derivative of a scalar field is called the gradient, and it can be represented as:
It always points in the direction of greatest increase of , and it has a magnitude equal to the maximum rate of increase at the point—just like a standard derivative. In particular, if a hill is defined as a height function over a plane , the gradient at a given location will be a vector in the xy-plane (visualizable as an arrow on a map) pointing along the steepest direction. The magnitude of the gradient is the value of this steepest slope.
In particular, this notation is powerful because the gradient product rule looks very similar to the 1d-derivative case:
However, the rules for dot products do not turn out to be simple, as illustrated by:
Divergence
The divergence of a vector field
is a scalar field that can be represented as:
The divergence is roughly a measure of a vector field's increase in the direction it points; but more accurately, it is a measure of that field's tendency to converge toward or diverge from a point.
The power of the del notation is shown by the following product rule:
The formula for the vector product is slightly less intuitive, because this product is not commutative:
Curl
The curl of a vector field is a vector function that can be represented as:
The curl at a point is proportional to the on-axis torque that a tiny pinwheel would be subjected to if it were centered at that point.
The vector product operation can be visualized as a pseudo-determinant:
Again the power of the notation is shown by the product rule:
The rule for the vector product does not turn out to be simple:
Directional derivative
The directional derivative of a scalar field in the direction
is defined as:
Which is equal to the following when the gradient exists
This gives the rate of change of a field in the direction of , scaled by the magnitude of . In operator notation, the element in parentheses can be considered a single coherent unit; fluid dynamics uses this convention extensively, terming it the convective derivative—the "moving" derivative of the fluid.
Note that is an operator that takes scalar to a scalar. It can be extended to operate on a vector, by separately operating on each of its components.
Laplacian
The Laplace operator is a scalar operator that can be applied to either vector or scalar fields; for cartesian coordinate systems it is defined as:
and the definition for more general coordinate systems is given in vector Laplacian.
The Laplacian is ubiquitous throughout modern mathematical physics, appearing for example in Laplace's equation, Poisson's equation, the heat equation, the wave equation, and the Schrödinger equation.
Hessian matrix
While usually represents the Laplacian, sometimes also represents the Hessian matrix. The former refers to the inner product of , while the latter refers to the dyadic product of :
.
So whether refers to a Laplacian or a Hessian matrix depends on the context.
Tensor derivative
Del can also be applied to a vector field with the result being a tensor. The tensor derivative of a vector field (in three dimensions) is a 9-term second-rank tensor – that is, a 3×3 matrix – but can be denoted simply as , where represents the dyadic product. This quantity is equivalent to the transpose of the Jacobian matrix of the vector field with respect to space. The divergence of the vector field can then be expressed as the trace of this matrix.
For a small displacement , the change in the vector field is given by:
Product rules
For vector calculus:
For matrix calculus (for which can be written ):
Another relation of interest (see e.g. Euler equations) is the following, where is the outer product tensor:
Second derivatives
When del operates on a scalar or vector, either a scalar or vector is returned. Because of the diversity of vector products (scalar, dot, cross) one application of del already gives rise to three major derivatives: the gradient (scalar product), divergence (dot product), and curl (cross product). Applying these three sorts of derivatives again to each other gives five possible second derivatives, for a scalar field f or a vector field v; the use of the scalar Laplacian and vector Laplacian gives two more:
These are of interest principally because they are not always unique or independent of each other. As long as the functions are well-behaved ( in most cases), two of them are always zero:
Two of them are always equal:
The 3 remaining vector derivatives are related by the equation:
And one of them can even be expressed with the tensor product, if the functions are well-behaved:
Precautions
Most of the above vector properties (except for those that rely explicitly on del's differential properties—for example, the product rule) rely only on symbol rearrangement, and must necessarily hold if the del symbol is replaced by any other vector. This is part of the value to be gained in notationally representing this operator as a vector.
Though one can often replace del with a vector and obtain a vector identity, making those identities mnemonic, the reverse is not necessarily reliable, because del does not commute in general.
A counterexample that demonstrates the divergence () and the advection operator () are not commutative:
A counterexample that relies on del's differential properties:
Central to these distinctions is the fact that del is not simply a vector; it is a vector operator. Whereas a vector is an object with both a magnitude and direction, del has neither a magnitude nor a direction until it operates on a function.
For that reason, identities involving del must be derived with care, using both vector identities and differentiation identities such as the product rule.
See also
Del in cylindrical and spherical coordinates
Notation for differentiation
Vector calculus identities
Maxwell's equations
Navier–Stokes equations
Table of mathematical symbols
Quabla operator
References
Willard Gibbs & Edwin Bidwell Wilson (1901) Vector Analysis, Yale University Press, 1960: Dover Publications.
External links
Vector calculus
Mathematical notation
Differential operators | Del | Mathematics | 1,781 |
18,953,543 | https://en.wikipedia.org/wiki/Tabby%20concrete | Tabby is a type of concrete made by burning oyster shells to create lime, then mixing it with water, sand, ash and broken oyster shells. Tabby was used by early Spanish settlers in present-day Florida, then by British colonists primarily in coastal South Carolina and Georgia. It is a man-made analogue of coquina, a naturally-occurring sedimentary rock derived from shells and also used for building.
Revivals in the use of tabby spread northward and continued into the early 19th century. Tabby was normally protected with a coating of plaster or stucco.
Origin
"Tabby" or "tapia" derives from the Spanish tabique de ostión (literally, "adobe wall of oyster [shell]").
There is evidence that North African Moors brought a predecessor form of tabby to Spain when they invaded the peninsula, but there is also evidence that the Iberian use is earlier and that it spread from there south to Morocco. A form of tabby is used in Morocco today and some tabby structures survive in Spain, though in both instances the aggregate is granite, not oyster shells.
It is likely that 16th-century Spanish explorers first brought tabby (which appears as , , and in early documents) to the coast of Florida in the sixteenth century. is Spanish for 'mud wall' and Arabic means 'a mixture of mortar and lime' or African tabi. In fact, the mortar used to chink the earliest cabins in this area was a mixture of mud and Spanish moss.
The oldest known example of tabby concrete in North America is the Spanish Fort San Antón de Carlos located on Mound Key in Florida.
Some researchers believe that English colonists developed their own process independently of the Spanish.
James Oglethorpe is credited with introducing "Oglethorpe tabby" into Georgia after seeing Spanish forts in Florida and encouraging its use, using it himself for his house near Fort Frederica. Later Thomas Spalding, who had grown up in Oglethorpe's house, led a tabby revival in the second quarter of the 19th century sometimes referred to as "Spalding tabby". Another revival occurred with the development of Jekyll Island in the 1880s.
Regions of use
Limestone to make building lime was not locally available to early settlers, so lime was imported or made from oyster shells. Shell middens along the coast were a supply of shells to make tabby, which diffused from two primary centers or hearths: one at Saint Augustine, Florida, and the other at Beaufort, South Carolina.
The British tradition began later (some time close to, but earlier than, 1700, upon introduction of the techniques from Spanish Florida) than the Spanish (1580), and spread far more widely as a building material, reaching at least as far north as Staten Island, New York, where it can be found in the still-standing Abraham Manee House, erected circa 1670. Beaufort, South Carolina, was both the primary center for British tabby and the location of the earliest British tabby in the southeastern US. It was here that the British tradition first developed, and from this hearth tabby eventually spread throughout the sea island district.
Herbert Eugene Bolton, John Tate Lanning, and other historians believed, from the mid-19th century into the middle of the 20th century, that tabby ruins in coastal Georgia and northeastern Florida were the remains of Spanish missions, even though local residents had earlier identified the ruins as those of late-18th century plantation buildings. The fact that the ruins were of structures built after the establishment of the Georgia Colony by Great Britain was not fully accepted by historians until late in the 20th century. With the exception of St. Augustine and, possibly, a few other important places, Spanish mission buildings were built with wooden posts supporting the roof and walls of palmetto thatch, wattle and daub or planks, or left open.
The LaPointe Krebs House, also known as the Old Spanish Fort (Pascagoula, Mississippi) is an extant tabby structure on the U.S. Gulf of Mexico. The house was constructed in 1757 in Louisiane, during the French Colonial period.
Tabby was used in the West Indies, including the islands of Antigua and Barbados.
Process
The labor-intensive process depended on slave labor to crush and burn the oyster shells into quicklime. The quicklime was then slaked (hydrated) and combined with more shells, sand, and water. It was poured or tamped into wood forms called cradles, built up in layers in a similar manner to rammed earth. Tabby was used in place of bricks, which could not be made locally because of the absence of local clay.
Tabby was used like concrete for floors, foundations, columns, roofs. Besides replacing bricks, it was also used as "oyster shell mortar" or "burnt shell mortar".
Significant examples
St. Simons Island Light, Georgia (foundation only)
Wormsloe Plantation house ruins, Isle of Hope, Georgia
McIntosh Sugarmill, Camden County, Georgia. Link to historical marker on McIntosh sugar works
Horton House, Jekyll Island, Georgia. There is a historical marker.
Slave quarters at Kingsley Plantation, Fort George Island, near Jacksonville, Florida
Bodiford Drug Store, Cedar Key, Florida
Heron Restaurant, Cedar Key, Florida
Island Hotel, Cedar Key, Florida
Isaac Fripp House Ruins, Saint Helena Island near Frogmore, South Carolina
Along Florida's west coast, Gamble Plantation Mansion, Ellenton
George Adderley House in Marathon, Florida
Colonial Dorchester State Historic Site near Charleston, South Carolina
Tabby Manse (Thomas Fuller House), Beaufort, South Carolina
The LaPointe Krebs House, also known as the Old Spanish Fort (Pascagoula, Mississippi)
See also
Bahareque
References
Further reading
External links
"Tabby: The Oyster Shell Concrete of the Lowcountry", Beaufort County, South Carolina Public Library.
Colin Brooker, "The Conservation and Repair of Tabby in Beaufort County, South Carolina", revised version of formal talk, "The Conservation of Tabby in Beaufort County, South Carolina," given at Jekyll Island Club Hotel, Jekyll Island, Georgia, on February 25, 1998.
Paper on Tabby by the Henry Ford Museum
Tabby historical marker at Jekyll Island
Building materials
Concrete
Tabby buildings | Tabby concrete | Physics,Engineering | 1,289 |
1,821,365 | https://en.wikipedia.org/wiki/Charles%20Parsons%20%28philosopher%29 | Charles Dacre Parsons (April 13, 1933 – April 19, 2024) was an American philosopher best known for his work in the philosophy of mathematics and the study of the philosophy of Immanuel Kant. He was professor emeritus at Harvard University. In a 2014 review of one of his books, Stewart Shapiro and Teresa Kouri said of Parsons: "It surely goes without saying that [he] is one of the most important philosophers of mathematics in our generation".
Life and career
Born on April 13, 1933, Charles Dacre Parsons was a son of Harvard sociologist Talcott Parsons. He earned his Ph.D. in philosophy at Harvard University in 1961, under the direction of Burton Dreben and Willard Van Orman Quine. He taught for many years at Columbia University before moving to Harvard University in 1989. He retired in 2005 as the Edgar Pierce professor of philosophy, a position formerly held by Quine.
Parsons was an elected Fellow of the American Academy of Arts and Sciences and the Norwegian Academy of Science and Letters.
Among his doctoral students were Michael Levin, James Higginbotham, Peter Ludlow, Gila Sher and Øystein Linnebo.
In 2017 Parsons gave the Gödel Lecture, titled Gödel and the Universe of Sets.
Parsons died in Cambridge, Massachusetts, on April 19, 2024, at the age of 91.
Philosophical work
In addition to his work in logic and the philosophy of mathematics, Parsons was an editor, with Solomon Feferman and others, of the posthumous works of Kurt Gödel. He has also written on historical figures, especially Immanuel Kant, Gottlob Frege, Kurt Gödel, and Willard Van Orman Quine.
Selected publications
Books
1983. Mathematics in Philosophy: Selected Essays. Ithaca, N.Y.: Cornell Univ. Press.
2008. Mathematical Thought and its Objects. Cambridge Univ. Press.
2012. From Kant to Husserl: Selected Essays. Cambridge, Massachusetts, and London: Harvard Univ. Press.
2014a. Philosophy of Mathematics in the Twentieth Century: Selected Essays. Cambridge, Massachusetts, and London: Harvard Univ. Press.
Articles
1987. "Developing Arithmetic in Set Theory without infinity: Some Historical Remarks". History and Philosophy of Logic, vol. 8, pp. 201–213.
1990a. "The Uniqueness of the Natural Numbers". Iyyun, vol. 39, pp. 13–44. ISSN 0021-3306.
1990b. "The Structuralist View of Mathematical Objects". Synthese, vol. 84 (3), pp. 303–346.
2014b. "Analyticity for Realists". In Interpreting Gödel: Critical Essays, ed. J. Kennedy. Cambridge University Press, pp. 131–150.
References
1933 births
2024 deaths
American logicians
Harvard Graduate School of Arts and Sciences alumni
Columbia University faculty
Harvard University Department of Philosophy faculty
Mathematical logicians
American philosophers of mathematics
Members of the Norwegian Academy of Science and Letters
People from Cambridge, Massachusetts | Charles Parsons (philosopher) | Mathematics | 618 |
20,963,719 | https://en.wikipedia.org/wiki/Metrication%20in%20Chile | Chile adopted the metric system in 1848. Previously, the Spanish system of measures was used.
Since colonization, Chile had always used a unit system based on the Spanish customary units. In 1843, a law was passed formalizing it, and defining its fundamental unit, the vara, as a fraction of a metre.
Later, during the presidency of Manuel Bulnes, a law was passed on 29 January 1848, adopting the Metric System. Finally, Chile signed the Metre Convention in 1908.
Current exceptions
Timber and pipes are sold in metres, but their width, thickness, and diameter are measured in inches.
Nail mass is measured in grams, but length is measured in inches.
Yarn is normally sold in yards.
Tins of paint are usually sold in multiples of US gallons.
Display sizes for the screens of televisions and computer monitors have their diagonals measured in inches.
Tire pressure is measured in pounds per square inch.
The most common paper size is letter (carta). A4 paper is rarely used.
The price of copper, Chile's most exported material, is usually quoted in dollars per pound.
In the Chiloé islands, the almud (a Spanish unit) is used as a volume measurement for "drys" (between six or eight litres).
McDonald's sells its Quarter Pounder with cheese as "Cuarto de Libra con Queso", which translates from Spanish as "Quarter Pound with Cheese".
Like in most countries, aviation (altitude and flight level) is measured in feet.
References
Chile
1848 in South America | Metrication in Chile | Mathematics | 317 |
66,411,817 | https://en.wikipedia.org/wiki/Thomas%20Ashburton%20Picken | Thomas Ashburton Picken (c. 1818 – 23 January 1891), known professionally as T. Picken, was a Scottish-born watercolourist, engraver and lithographer working in England between around 1834 and 1875. He worked for the printing firm Day and Haghe (later Day & Son) for many years, and first came to notice for his lithograph of The Destruction of Both Houses of Parliament when he was only about 16 years old. Although there is no evidence that he travelled abroad, he produced many lithographs of foreign parts after paintings by other artists. He specialised in detailed images of landscape, architecture, events of war, and ships. He produced lithographs of SS Great Eastern and the laying of the Atlantic cable, and he illustrated books.
Picken's father was the Scots novelist Andrew Picken, and his brother Andrew was a lithographer who also trained with Day and Haghe. Picken ended his days as a Poor Brother at The London Charterhouse, alongside his brother, James Canning (or Channing) Picken. His lithographs are now in many collections, including the Royal Collection Trust, the Library of Congress collection and the Royal Academy collection.
Arts background
Picken's father was Scots writer Andrew Picken (Paisley 1788 – London 23 November 1833), who published various novels including Traditional stories of old families (1833). Thomas' mother was Janet E. Coxon (or Coxson) (1793 – South Stoneham 1871). Andrew Picken senior's first book, Tales and Sketches of the West of Scotland (1824), about historical changes there, "gave great offence to the citizens of Glasgow" and this drove him out of the town. He died in London, where his family were "left in very precarious circumstances" when his son Thomas was around 15 years old. Thomas Picken was one of four sons, three of whom were lithographers. Two of his elder brothers were the lithographer Andrew (1815 – London 24 June 1845) and lithographic artist (later wine merchant) James Canning (or Channing) (Dublin ca.1817 – Brentford 1899). He had two younger sisters: Sophia (b. Glasgow 14 December 1821), and Eleanor Emma (Glasgow ca.1822 – Portsea 21 July 1898) who, as a miniaturist portrait painter, exhibited at the Royal Academy in 1842.
Life
Thomas Ashburton Picken was born around 1818, in Govan, Glasgow. He never married. In 1841 he was living in Great Randolph Street, Kentish Town, London, with his mother Janet, his brother James, and his sisters Emma and Sophia, and describing himself as an artist. In 1851 the census finds him living at 13 Murray Street, Camden, with his brother James and his sister Sophia. By 1861 he was lodging at 27 Rutland Street, St Pancras, London, with the family of sculptor Thomas Woolner (1825–1892). In 1871 he was living as a lodger at 11 Rutland Street, describing himself as a lithographic artist.
Picken and his brother James Canning (or Channing) Picken were accepted as Poor Brothers or male pensioners at the Charterhouse, London. Thomas was described there as a former lithographer and James as a former wine merchant, and Thomas was registered in 1879. On 23 January 1891 he died at the Charterhouse. He was buried on 24 January 1891 with his brother Andrew on the west side of Highgate Cemetery.
Career
Since Thomas Picken was working for Day and Haghe, later Day & Son, in 1834 at the age of around sixteen years, and served the company for the rest of his career, it is likely that he served his apprenticeship there, as did his brother Andrew. He was working as a watercolourist, engraver, lithographer and painter for that company in Camden, London from at least 1834, and flourished until at least 1875.
Probably one of Picken's earliest publications was his lithograph of The Destruction of Both Houses of Parliament, 1834, executed when he was only about 16 years old. No other original artist is credited for this work, so it is not impossible that the initial sketches were undertaken by Picken himself. The authorship of original works on which lithographs were based was usually credited, but such works are often unavailable. Therefore, the question arises as to the extent to which the mid-19th-century lithographers were responsible for the final composition and detail of their engravings. The Day and Haghe lithographer William Simpson said, "In lithography ... we [at times] had to work out rough materials into pictures ... if a man has any stuff in him it finds development."
No evidence of foreign travel has been found, but many of Picken's works after other artists represent locations around the world. He made detailed images of landscape, architecture, events of war, and ships. He illustrated books, and produced lithographs of SS Great Eastern, and the laying of the Atlantic cable.
Selected works
Palace of Westminster: Destruction of both Houses of Parliament, as seen from the Surrey side (1834), by Thomas Ashburton Picken.
Palace of Westminster: Destruction of both Houses of Parliament as seen from Abingdon Street on the Night of October 16th 1834 (1834), by Thomas Ashburton Picken.
King's College Hospital. North or entrance front (ca.1842), after architect Thomas Bellamy (1798–1876).
View of Quebec City, Canada (1845), after the artist and topographical engineer Benjamin Beaufoy (1814–1879).
St Paul's Cathedral (1851), after artist George Sidney Shepherd (ca.1786–1862).
Horse Guards Parade: General view (1851), after George Sidney Shepherd.
Wellington Arch, Hyde Park Corner (1852), after Louis Haghe (1806–1885).
The Great Eastern under weigh July 23rd (circa 1860).
Native Village and Palaver House near Cavalla (1868) after George Townshend Fox (1810–1886).
Some lithographs
Works published as sets
The eight engravings were lithograph copies by Thomas Ashburton Picken of Frances Emilia Crofton's original paintings.
. (This is a bound set of lithographs after Edmund Walker, rather than an illustrated book: Westminster Abbey; General Post Office; Greenwich Hospital; The Treasury Whitehall; The Quadrant Regent Street; St Paul's Cathedral, St Martin's Church; Trafalgar Square; Royal Exchange; Buckingham Palace; London Bridge; British Museum).
Book illustration
(In date order)
(Lithographs after David Roberts).
(Thomas Picken is credited for some of the lithographs).
(At least one lithograph in this book is by Picken after Pyne. Pyne is sometimes listed as "Payne".)
.(Lithographs after William Simpson, Sir William Allan, Clarkson Frederick Stanfield, George Cattermole, William Leighton Leitch, Thomas Creswick, David Roberts, James Duffield Harding, Joseph Nash, Horatio McCulloch, J. M. W. Turner, David Octavius Hill).
(Lithographs after James Baker Pyne).
(Lithograph plate XI after B. Spackman).
(Some of the illustrations are lithographed by Picken).
Exhibitions
Royal Academy of Arts (1857): One watercolour, The Castle Rock, Lynton, North Devon.
Society of Artists of Great Britain (1846–75): ten watercolours.
Collections
Besides the list below, Picken's lithographs are in numerous collections, including: Museum of Science and Industry, Victoria and Albert Museum, Government Art Collection, Library of Congress Collection, Museum of London, National Army Museum, National Library of Poland, National Maritime Museum, London, National Railway Museum, People's Collection, Wales, Royal Academy collection, Royal Museums Greenwich, University of British Columbia, University of Edinburgh collection, Villanova University, Yale Center for British Art, and the British Museum.
Royal Collection Trust: Five of the prints from the Eight Views set (1854), including Killarney, Dunbroody Abbey, Lough Rynn, Muckruss Abbey and Castle Otway after Frances Emilia Crofton, and Launch of the Trafalgar (1842) by T.A. Picken after William Ranwell.
Guildhall Library print room, Wakefield Collection: St Paul's Cathedral (1851).
London Metropolitan Archives and Guildhall Art Gallery: Palace of Westminster: Destruction of both Houses of Parliament, as seen from the Surrey side (1834), Palace of Westminster: Destruction of both Houses of Parliament as seen from Abingdon Street on the Night of 16th October 1834 (1834), Horse Guards Parade: General view (1851), Wellington Arch, Hyde Park Corner (1852),
Wellcome Collection: King's College Hospital. North or entrance front (ca.1842), after Thomas Bellamy, People strolling along Old Well Walk, Cheltenham (1842) by T. Picken after W. Hughes.
National Library of Wales, Welsh Landscape Collection: Various lithographs including Conwy Tubular Bridge (1849) after S. Crowther.
Reviews
Messrs Ackerman of the Strand have just brought out a beautiful lithograph representation of the Launch of the Trafalgar drawn by Mr Ranwell and lithographed by Mr T. Picken. So far as our acquaintance with art goes, this is the first attempt that has been made to do full justice, by pictorial representation, to that soul-stirring scene to every Englishman - a ship launch. The artist could not have made a better selection of subject than the one he has chosen. The launch of the Trafalgar presented, perhaps, the most animating scene of joyousness that ever occurred in this country. More brilliant assemblages take place at Coronations and other great state ceremonies; but the glitter of a pageant has always a certain coldness associated with its formalities. Here, however, was a kind of undress scene of royalty - a monarch brought into immediate contact with her people, and sharing with them in feelings which form their mutual security. Those who were present can never forget the scene - a scene from which, with its multitudinous objects, we should have considered beyond the reach of pictorial art, if we had not seen Mr Ranwell's admirable delineation of the subject. The moment which the artist has perpetuated in the beautiful lithograph before us, is that in which the noble vessel descended majestically into the water, amid the heartwarming huzzas of countless thousands. The situation of the spectator is on the river below the slip - a line of yachts, barges and other craft, with their crowded docks forming the immediate foreground. The figures are admirably disposed and brought up with all the sharpness of a line engraving. - Intermediately is a patch of water with a few light row-boats, and then a line of steamers with their thronged and brilliant assemblages. Next, occupying the centre of the picture, is the noble vessel herself, just settling into the water, a sufficient space being left between her bow and entrance of the dock to discover the Royal party. To describe the various accessory aids which the artist has judiciously drawn into his subject would occupy a page; whilst we only have space left to observe generally that this splendid specimen of lithography is a perfect novelty in art. We had no conception so large a drawing crowded with thousands of figures could be attempted by this process with any chance of success - whilst in distinctness of outline, in sharpness and clearness of body, in delicacy of lights and in fulness of tone his magnificent picture has, as we previously observed, all the power of a line engraving; and as a specimen of lithography stands without a rival. ("Launch of the Trafalgar", Kentish Mercury, 12 March 1842).
Bath from Sham Castle drawn on stone by T. Picken, from a painting by J. Syer. A very beautiful lithograph engraving of the city of Bath has recently been published by Mr Everitt, of the Repository of Arts in that town. The view is taken from Sham Castle, and the town appears unfolded as a map, all the streets and principal buildings being represented with the strictest regard to topographical accuracy. The surrounding country is also seen for many miles, and independently of the value of the engraving in an historical point of view, and as a work of reference, it is commendable for its general fidelity to nature and artistic treatment. ("Bath from Sham Castle", Morning Post, 28 September 1850).
Further research
Notes
References
External links
1818 births
1891 deaths
Burials at Highgate Cemetery
English lithographers
Draughtsmen
English illustrators
English watercolourists
Scottish lithographers
Scottish illustrators
Scottish watercolourists | Thomas Ashburton Picken | Engineering | 2,702 |
1,648,875 | https://en.wikipedia.org/wiki/Wilkinson%20power%20divider | In the field of microwave engineering and circuit design, the Wilkinson Power Divider is a specific class of power divider circuit that can achieve isolation between the output ports while maintaining a matched condition on all ports. The Wilkinson design can also be used as a power combiner because it is made up of passive components and hence is reciprocal. First published by Ernest J. Wilkinson in 1960, this circuit finds wide use in radio frequency communication systems utilizing multiple channels since the high degree of isolation between the output ports prevents crosstalk between the individual channels.
It uses quarter wave transformers, which can be easily fabricated as quarter wave lines on printed circuit boards. It is also possible to use other forms of transmission line (e.g. coaxial cable) or lumped circuit elements (inductors and capacitors).
Theory
The scattering parameters for the common case of a 2-way equal-split Wilkinson power divider at the design frequency is given by
Inspection of the S matrix reveals that the network is reciprocal (), that the terminals are matched (), that the output terminals are isolated (=0), and that equal power division is achieved (). The non-unitary matrix results from the fact that the network is lossy. An ideal Wilkinson divider would yield .
Network theorem governs that a divider cannot satisfy all three conditions (being matched, reciprocal and loss-less) at the same time. Wilkinson divider satisfies the first two (matched and reciprocal), and cannot satisfy the last one (being loss-less). Hence, there is some loss occurring in the network.
No loss occurs when the signals at ports 2 and 3 are in phase and have equal magnitude. In case of noise input to ports 2 and 3, the noise level at port 1 does not increase, half of the noise power is dissipated in the resistor.
By cascading, the input power might be divided to any -number of outputs.
Unequal/Asymmetric Division Through Wilkinson Divider
If the arms for port 2 and 3 are connected with un-equal impedances, then asymmetric division of power can be achieved.
When characteristic impedance is , and one wants to split power as and , and ≠ , then the design can be created following the equations:
A new constant is defined for ease of expression, where
Then the design guideline is:
The equal-splitting Wilkinson Divider is obtained for .
See also
Power dividers and directional couplers
References
External links
Online Wilkinson Power Split Calculator
Online Resistive Power Split Calculator
Online Coaxial Power Split Calculator
Wilkinson power divider tutorial with other power divider / combiner pages
Lumped element Wilkinson power divider example
Microwave technology
Radio electronics | Wilkinson power divider | Engineering | 556 |
35,901,550 | https://en.wikipedia.org/wiki/Design%20Management%20Europe%20Award | The Design Management Europe Award (DME) is a European Design management prize. The DME Award aims to promote the strategic use of design within European businesses. It awards the management and successful implementation of design in their processes and strategies to achieve their business goals. The DME Network consists of 24 partners from 17 different countries that have been organizing the DME Award since 2007.
History
ADMIRE (Award for Design Management Innovating and Reinforcing Enterprises, January 2007 – February 2009)
The DME Award started off as part of the ADMIRE programme in January 2007. The ADMIRE programme was a 2-year project in the European PRO – INNO programme of the Directorate-General for Enterprise and Industry of the European Commission. The 6.4 million Euro programme addressed the Innovation management agenda of PRO – INNO Europe by raising the awareness of Design Management, in particular amongst European small and medium enterprises, to improve their competitiveness and to boost the European economy in general. It was one of the key project objectives to establish the DME Award. 18 European organisations participated in this programme under the coordination of the City of Eindhoven until the end of the ADMIRE project in February 2009.
DME Organisation (February 2009 – Present)
The former ADMIRE partners have been organising the DME Award since the end of the funded ADMIRE project on a voluntary basis. The role of these DME partners is to promote and organize the annual DME Award. For this purpose, a DME Award board was elected. The board consists of five representatives from the following organisations:
Cardiff Metropolitan University
City of Eindhoven
European Design Centre
Design Austria
The costs of the DME Award ceremony are covered by the hosting cities and entering the Award is free for all participants. The entrants are challenged to represent their Design Management processes, strategies and procedures in poster format. These posters are judged by a jury of internationally recognised Design Management experts.
Judging criteria
The DME judging Criteria are:
Resources : Level of allocated resources
Awareness of Benefits : Level of added value through design.
Planning : Plans, objectives and integration of design.
Process : The process for the use of design.
Expertise : Level of employment of internal and external expertise.
Categories
Current categories
Large Company:
Open to private companies with 250 employees or more or with an annual turnover in excess of €50,000,000
Medium-sized Company:
Open to private companies with 50 to 249 employees or with an annual turnover not in excess of €50,000,000
Small Company:
Open to private companies with 10 to 49 employees and with an annual turnover not in excess of €10,000,000
Micro Company:
Open to private companies with 9 employees or less and with an annual turnover not in excess of €2,000,000
Public or non–profit organisation (NPO):
Open to public or non–profit organisations such as charities, government programmes, city councils or schools and colleges
Organisations outside of Europe
Open to any private companies and public or non-profit organisations operating outside of Europe.
Previous categories
First time design project (2007–2010):
This category was specific to SMEs (less than 250 employees and a turnover not in excess of €50,000,000). The purpose of this category was to showcase good examples of organisations managing design for the first time. This could have either come from established organisations or from start – ups.
Design strategy for sustainability (2008–2009):
This category was open to private companies and public organisations of all sizes. Sustainability relates to design strategies encompassing social responsibility, improving the environment or reducing ecological impact.
DME Award Partners
In 2011 the DME Award consortium consisted of the following partners:
DME Award Ceremonies
2007: Essen, Germany
2008: Cardiff, United Kingdom
2009: Eindhoven, The Netherlands
2010: Lisbon, Portugal
2011: Tallinn, Estonia
2012: Paredes, Portugal
DME Award Winners
References
Design awards
Management awards | Design Management Europe Award | Technology,Engineering | 783 |
41,094 | https://en.wikipedia.org/wiki/Electromagnetic%20environment | In telecommunications, the term electromagnetic environment (EME) has the following meanings:
For a telecommunications system, the spatial distribution of electromagnetic fields surrounding a given site. The electromagnetic environment may be expressed in terms of the spatial and temporal distribution of electric field strength (volts per metre), irradiance (watts per square metre), or energy density (joules per cubic metre).
The resulting product of the power and time distribution, in various frequency ranges, of the radiated or conducted electromagnetic emission levels that may be encountered by a military force, system, or platform when performing its assigned mission in its intended operational environment. It is the sum of electromagnetic interference; electromagnetic pulse; hazards of electromagnetic radiation to personnel, ordnance, and volatile materials; and natural phenomena effects of lightning and p-static.
All electromagnetic phenomena observable in a given location.
References
Electromagnetic radiation
Telecommunications engineering
Electromagnetic compatibility
Reliability engineering | Electromagnetic environment | Physics,Engineering | 182 |
5,172,282 | https://en.wikipedia.org/wiki/G%20Centauri | G Centauri is a single star in the southern constellation of Centaurus. It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude of +4.82. This object is located approximately 450 light years from the Sun, based on parallax. It is a member of the Lower Centaurus–Crux group of the Scorpius–Centaurus association, with the former having an age of about 17 million years.
This object is a B-type main-sequence star with a stellar classification of B3V(n), where the 'n' indicates "nebulous" (broad) lines due to rapid rotation. It is around 16 million years old with a projected rotational velocity of up to 298 km/s. The star has six times the mass of the Sun and 3.4 times the Sun's radius. It is radiating 483 times the luminosity of the Sun from its photosphere at an effective temperature of 13,732 K. An infrared excess indicates a circumstellar disk of dust with a mean temperature of 50 K is orbiting the star at a separation of .
References
B-type main-sequence stars
Circumstellar disks
Centaurus
Centauri, G
Durchmusterung objects
108257
060710
4732
Lower Centaurus Crux | G Centauri | Astronomy | 283 |
6,648,322 | https://en.wikipedia.org/wiki/Flexible%20display | A flexible display or rollable display is an electronic visual display which is flexible in nature, as opposed to the traditional flat screen displays used in most electronic devices. In recent years there has been a growing interest from numerous consumer electronics manufacturers to apply this display technology in e-readers, mobile phones and other consumer electronics. Such screens can be rolled up like a scroll without the image or text being distorted. Technologies involved in building a rollable display include electronic ink, Gyricon, Organic LCD, and OLED.
Electronic paper displays which can be rolled up have been developed by E Ink. At CES 2006, Philips showed a rollable display prototype, with a screen capable of retaining an image for several months without electricity. In 2007, Philips launched a 5-inch, 320 x 240-pixel rollable display based on E Ink’s electrophoretic technology. Some flexible organic light-emitting diode displays have been demonstrated.The first commercially sold flexible display was an electronic paper wristwatch. A rollable display is an important part of the development of the roll-away computer.
Applications
With the flat panel display having already been widely used more than 40 years, there have been many desired changes in the display technology, focusing on developing a lighter, thinner product that was easier to carry and store. Through the development of rollable displays in recent years, scientists and engineers agree that flexible flat panel display technology has huge market potential in the future.
Rollable displays can be used in many places:
Mobile devices.
Laptops and PDAs.
A permanently conformed display that securely fits around the wrists.
A child's mask for Halloween and other uses.
An odd-shaped display integrated in a steering wheel or automobile.
History
Flexible electronic paper based displays
Flexible electronic paper (e-paper) based displays were the first flexible displays conceptualized and prototyped. While the idea for this type of display is not recent and had been attempted by several companies in the past, only recently has mass production of this technology begun for implementation in consumer electronic devices.
Xerox PARC
The concept of developing a flexible display was first put forth by Xerox PARC (Palo Alto Research Company). In 1974, Nicholas K. Sheridon, a PARC employee, made a major breakthrough in flexible display technology and produced the first flexible e-paper display. Dubbed Gyricon, this new display technology was designed to mimic the properties of paper, but married with the capacity to display dynamic digital images. Sheridon envisioned the advent of paperless offices and sought commercial applications for Gyricon. In 2003 Gyricon LLC was formed as a direct subsidiary of Xerox to commercialize the electronic paper technology developed at Xerox PARC. Gyricon LLC's operations were short lived and in December 2005 Xerox closed the subsidiary company in a move to focus on licensing the technology instead.
HP and ASU
In 2005, Arizona State University (ASU) opened a 250,000 square foot facility dedicated to flexible display research named the ASU Flexible Display Center (FDC). ASU received $43.7 million from the U.S. Army Research Laboratory (ARL) towards the development of this research facility in February 2004. A planned prototype device was slated for public demonstration later that year. However, the project met a series of delays. In December 2008, ASU in partnership with Hewlett Packard demonstrated a prototype flexible e-paper from the Flexible Display Center at the university. HP continued on with the research, and in 2010, showcased another demonstration. However, due to limitations in technology, HP stated "[our company] doesn't actually see these panels being used in truly flexible or rollable displays, but instead sees them being used to simply make displays thinner and lighter."
Between 2004–2008, ASU developed its first small-scale flexible displays. Between 2008–2012, ARL committed to further sponsorship of ASU’s Flexible Display Center, which included an additional $50 million in research funding. Although the U.S. Army funds ASU’s development of the flexible display, the center’s focus is on commercial applications.
Plastic Logic
Plastic Logic is a company that develops and manufactures monochrome plastic flexible displays in various sizes based on its proprietary organic thin film transistor (OTFT) technology. They have also demonstrated their ability to produce colour displays with this technology, however they are currently not capable of manufacturing them on a large scale. The displays are manufactured in the company's purpose-built factory in Dresden, Germany, which was the first factory of its kind to be built – dedicated to the high volume manufacture of organic electronics. These flexible displays are cited as being "unbreakable", because they are made completely of plastic and do not contain glass. They are also lighter and thinner than glass-based displays and low-power. Applications of this flexible display technology include signage, wristwatches and wearable devices as well as automotive and mobile devices.
Organic User Interfaces and the Human Media Lab
In 2004, a team led by Prof. Roel Vertegaal at Queen's University's Human Media Lab in Canada developed PaperWindows, the first prototype bendable paper computer and first Organic User Interface. Since full-colour, US Letter-sized displays were not available at the time, PaperWindows deployed a form of active projection mapping of computer windows on real paper documents that worked together as one computer through 3D tracking. At a lecture to the Gyricon and Human-Computer Interaction teams at Xerox PARC on 4 May 2007, Prof. Vertegaal publicly introduced the term Organic User Interface (OUI) as a means of describing the implications of non-flat display technologies on user interfaces of the future: paper computers, flexible form factors for computing devices, but also encompassing rigid display objects of any shape, with wrap-around, skin-like displays. The lecture was published a year later as part of a special issue on Organic User Interfaces in the Communications of the ACM. In May 2010, the Human Media Lab partnered with ASU's Flexible Display Center to produce PaperPhone, the first flexible smartphone with a flexible electrophoretic display. PaperPhone used bend gestures for navigating contents. Since then, the Human Media Lab has partnered with Plastic Logic and Intel to introduce the first flexible tablet PC and multi-display e-paper computer, PaperTab, at CES 2013, debuting the world's first actuated flexible smartphone prototype, MorePhone in April 2013.
Others
Since 2010, Sony Electronics, AU Optronics and LG Electronics have all expressed interest in developing flexible e-paper displays. However, only LG have formally announced plans for mass production of flexible e-paper displays.
Flexible OLED-based displays
Research and development into flexible OLED displays largely began in the late 2000s with the main intentions of implementing this technology in mobile devices. However, this technology has recently made an appearance, to a moderate extent, in consumer television displays as well.
Nokia Morph and Kinetic concepts
Nokia first conceptualized the application of flexible OLED displays in mobile phone with the Nokia Morph concept mobile phone. Released to the press in February 2008, the Morph concept was project Nokia had co-developed with the University of Cambridge. With the Morph, Nokia intended to demonstrate their vision of future mobile devices to incorporate flexible and polymorphic designs; allowing the device to seamlessly change and match a variety of needs by the user within various environments. Though the focus of the Morph was to demonstrate the potential of nanotechnology, it pioneered the concept of utilizing a flexible video display in a consumer electronics device. Nokia renewed their interest in flexible mobile devices again in 2011 with the Nokia Kinetic concept. Nokia unveiled the Kinetic flexible phone prototype at Nokia World 2011 in London, alongside Nokia’s new range of Windows Phone 7 devices. The Kinetic proved to be a large departure from the Morph physically, but it still incorporated Nokia's vision of polymorphism in mobile devices.
Sony
Sony Electronics has expressed interest for research and development towards a flexible display video display since 2005. In partnership with RIKEN (the Institute of Physical and Chemical Research), Sony promised to commercialize this technology in TVs and cellphones sometime around 2010. In May 2010 Sony showcased a rollable TFT-driven OLED display.
Samsung
In late 2010, Samsung Electronics announced the development of a prototype 4.5 inch flexible AMOLED display. The prototype device was then showcased at Consumer Electronics Show 2011. During the 2011 Q3 quarterly earnings call, Samsung’s vice president of investor relations, Robert Yi, confirmed the company’s intentions of applying the technology and releasing products utilizing it by early 2012. In January 2012 Samsung acquired Liquavista, a company with expertise in manufacturing flexible displays, and announced plans to begin mass production by Q2 2012.
In January 2013, Samsung exposed its brand new, unnamed product during the company's keynote address at CES in Las Vegas. Brian Berkeley, the senior vice president of Samsung's display lab in San Jose, California had announced the development of flexible displays. He said "the technology will let the company's partners make bendable, rollable, and foldable displays," and he demonstrated how the new phone can be rollable and flexible during his speech.
During Samsung's CES 2013 keynote presentation, two prototype mobile devices codenamed "Youm" that incorporated the flexible AMOLED display technology were shown to the public. "Youm" has curved display screen, the use of OLED screen giving this phone deeper blacks and a higher overall contrast ratio with better power efficiency than traditional LCD displays. Also this phone has the advantages of a rollable display; it is lighter, thinner, and more durable than LCD displays. Samsung stated that "Youm" panels will be seen in the market in a short time and production will commence in 2013.
Samsung subsequently released the Galaxy Round, a smartphone with an inward curving screen and body, in October 2013. One of the Youm concepts, which featured a curved screen edge used as a secondary area for notifications and shortcuts, was developed into the Galaxy Note Edge released in 2014. In 2015, Samsung applied the technology to its flagship Galaxy S series with the release of the Galaxy S6 Edge, a variant of the S6 model with a screen sloped over both sides of the device. During a developer conference in 2018, Samsung showed a foldable smartphone prototype, which was subsequently revealed in February 2019 as the Galaxy Fold.
ASU
The Flexible Display Center (FDC) at Arizona State University announced a continued effort in forwarding flexible displays in 2012. On 30 May, in partnership with Army Research Lab scientists, ASU announced that it has successfully manufactured the world's largest flexible OLED display using thin-film transistor (TFTs) technology. ASU intends the display to be used in "thin, lightweight, bendable and highly rugged devices."
Xiaomi
In January 2019, Chinese manufacturer Xiaomi showed a foldable smartphone prototype. CEO Lin Bin of Xiaomi demoed the device in a video on the Weibo social network. The device features a large foldable display that curves 180 degrees inwards on two sides. The tablet turns into a smartphone, with a screen diagonal of 4,5 inch, adjusting the user interface on the fly.
Advantages
Flexible displays have many advantages over glass: better durability, lighter weight, thinner as plastic, and can be perfectly curved and used in many devices. Moreover, the major difference between glass and rollable display is that the display area of a rollable display can be bigger than the device itself; If a flexible device measuring, for example, 5 inches in diagonal and a roll of 7.5mm, it can be stored in a device smaller than the screen itself and close to 15mm in thickness.
Technical details
Electronic paper
Flexible displays that use electronic paper technology commonly use Electrophoretic or Electrowetting technologies. However, each type of flexible electronic paper varies in specification due to different implementation techniques by different companies.
HP and ASU e-paper
The flexible electronic paper display technology co-developed by Arizona State University and HP employs a manufacturing process developed by HP Labs called Self-Aligned Imprint Lithography (SAIL). The screens are made by layering stacks of semi-conductor materials and metals between pliable plastic sheets. The stacks need to be perfectly aligned and stay that way. Alignment proves difficult during manufacturing when heat during manufacturing can deform the materials and when the resulting screen also needs to remain flexible. The SAIL process gets around this by ‘printing’ the semiconductor pattern on a fully composed substrate, so that the layers always remain in perfect alignment. The limitation of the material the screen is based on allows only a finite amount of full rolls, hence limiting its commercial application as a flexible display. Specifications provided regarding the prototype display are as follows:
flexible and rollable up to "about half a dozen times"
"unbreakable"
AUO e-paper
The flexible electronic paper display announced by AUO is unique as it is the only solar powered variant. A separate rechargeable battery is also attached when solar charging is unavailable.
Specifications
6-inch diagonal display size
radius of curvature can reach 100mm
9:1 high contrast ratio
reflectance of 33%
16 gray levels
solar powered
"unbreakable"
LG e-paper
Specifications:
6-inch diagonal display size
1024x768 (XGA) resolution
4:3 aspect ratio
TFT based electronic display
"allows bending at a range of 40 degrees from the center of the screen"
0.7mm thickness from the side
14g weight
can drop from 1.5m above ground with no resultant damage
"unbreakable" (from tests with a small urethane hammer)
List of displays by their reported curvature
*Lower is more sharply curved
OLED
Many of the e-paper based flexible displays are based on OLED technology and its variants. Though this technology is relatively new in comparison with e-paper based flexible displays, implementation of OLED flexible displays saw considerable growth in the last few years.
ASU
Specifications:
6-inch diagonal display size
480x360 4k resolution
4:3 aspect ratio
OLED display technology with a TFT back plane
Samsung
Specifications:
4.5-inch diagonal display size
800x480 WVGA, 1280x720 WXGA and WQXGA (2560×1600) resolutions
AMOLED display technology
"unbreakable"
Concept devices
Mobile devices
In May 2011, Human Media Lab at Queen's University in Canada introduced PaperPhone, the first flexible smartphone, in partnership with the Arizona State University Flexible Display Center. PaperPhone used 5 bend sensors to implement navigation of the user interface through bend gestures of corners and sides of the display. In January 2013, the Human Media Lab introduced the first flexible tablet PC, PaperTab, in collaboration with Plastic Logic and Intel Labs, at CES. PaperTab is a multi-display environment in which each display represents a window, app or computer document. Displays are tracked in 3D to allow multidisplay operations, such as collate to enlarge the display space, or pointing with one display onto another to pull open a document file. In April 2013 in Paris, the Human Media Lab, in collaboration with Plastic Logic, unveiled the world's first actuated flexible smartphone prototype, MorePhone. MorePhone actuates its body to notify users upon receiving a phone call or message.
Nokia introduced the Kinetic concept phone at Nokia World 2011 in London. The flexible OLED display allows users to interact with the phone by twisting, bending, squeezing and folding in different manners across both the vertical and horizontal planes. The technology journalist website Engadget described interactions such as "[when] bend the screen towards yourself, [the device] acts as a selection function, or zooms in on any pictures you're viewing." Nokia envisioned this type of device to be available to consumers in "as little as three years", and claimed to already possess "the technology to produce it."
At CES 2013, Samsung showcased the two handsets which incorporates AMOLED flexible display technology during its keynote presentation, the Youm and an unnamed Windows Phone 8 prototype device. The Youm possessed a static implementation of flexible AMOLED display technology, as its screen has a set curvature along one of its edges. The benefit of the curvature allows users "to read text messages, stock tickers, and other notifications from the side of the device even if [the user] have a case covering the screen." The unnamed Windows Phone 8 prototype device was composed of a solid base from that extends a flexible AMOLED display. The AMOLED display itself bends and was described as "virtually unbreakable even when dropped" according to Samsung representatives. Brian Berkeley, the senior vice president of Samsung Display, believes that this flexible form factor "will really begin to change how people interact with their devices, opening up new lifestyle possibilities ... [and] allow our partners to create a whole new ecosystem of devices." The Youm's form factor was ultimately utilized on the Galaxy Note Edge, and future Samsung Galaxy S series devices.
ReFlex is a flexible smartphone created by Queen's University’s Human Media Lab.
Curved OLED TVs
LG Electronics and Samsung Electronics both introduced curved OLED televisions with a curved display at CES 2013 hours apart from each other. Both companies recognized their respective curved OLED prototype television as a first-of-its-kind due to its flexed OLED display. The technology journalist website The Verge noted the subtle curve on 55" Samsung OLED TV allowed it to have a "more panoramic, more immersive viewing experience, and actually improves viewing angles from the side." The experience was also shared viewing the curved 55" LG OLED TV. The LG set is also 3D capable, in addition to the curvature.
*Lower is more sharply curved
See also
Organic user interface (OUI), the category of user interfaces commonly implemented on consumer devices with flexible displays.
Flexible glass
Fish scale
Modular design
Smart watch
MSG Sphere
Evans & Sutherland
References
Flexible displays
Display technology
Electronic paper technology
Liquid crystal displays
Flexible electronics | Flexible display | Materials_science,Mathematics,Engineering | 3,728 |
47,953,116 | https://en.wikipedia.org/wiki/RAET1G | Retinoic acid early transcript 1G (RAET1G) is a cell surface glycoprotein encoded by RAET1G gene located on chromosome 6. RAET1G is related to MHC class I molecules, but its gene maps outside the MHC locus. RAET1G is composed of an external α1α2 domain, a transmembrane segment, and C-terminal cytoplasmic tail. RAET1E functions as a stress-induced ligand for NKG2D receptors.
References
Glycoproteins | RAET1G | Chemistry | 117 |
1,197,808 | https://en.wikipedia.org/wiki/Sleep-learning | Sleep-learning or sleep-teaching (also known as hypnopædia or hypnopedia) is an attempt to convey information to a sleeping person, typically by playing a sound recording to them while they sleep. Although sleep is considered an important period for memory consolidation, scientific research has concluded that sleep-learning is not possible. It appears frequently in fiction.
History
In 1927, Alois Benjamin Saliger invented the Psycho-Phone for sleep learning, stating: "It has been proven that natural sleep is identical with hypnotic sleep and that during natural sleep the unconscious mind is most receptive to suggestions."
Since the electroencephalography studies by Charles W. Simon and William H. Emmons in 1956, learning by sleep has not been taken seriously. The researchers concluded that learning during sleep was "impractical and probably impossible". They reported that stimulus material presented during sleep was not recalled later when the subject awoke, unless alpha wave activity occurred at the same time the stimulus material was given.
In fiction
Sleep-learning is found in influential science fiction and other literature. The following examples are listed chronologically by publication or original air date, when known.
In Hugo Gernsback's 1911 story Ralph 124C 41+, one finds the Hypnobioscope, a sleep learning device.
In Aldous Huxley's 1932 novel Brave New World, it is used for the conditioning of children into the novel's fictional future culture. In the novel, sleep-learning was discovered by accident when a Polish boy named Reuben Rabinovitch was able to recite an entire radio broadcast in English after a radio receiver was left on in his sleep. The boy was unable to comprehend what he had heard via hypnopædia, but it was soon realized that hypnopædia could be used to effectively make suggestions about morality.
In Robert Heinlein's 1948 novel Space Cadet, the character Matt Dodson is taught to speak Venutian (the language of the planet Venus) while under drug-aided hypnosis. He surprises his Venus-born friend Oscar by spontaneously reproving him when Oscar utters a curse in Venutian. (Later in the novel, Matt appears to have forgotten what he learned and relies on Oscar for translation.)
In the BBC Radio series Journey into Space (1953–1958), during the second and third parts of the trilogy, there were said to be Martians abducting people from the Earth and conditioning them to obey instructions or to make them believe things that were not true. The inception of this conditioning involved putting the subject into a hypnotic sleep and appraising them of a certain situation; once they awoke they would believe it, regardless of the validity.
In a 1961 episode of My Three Sons, "A Lesson In Any Language", Mike connects a phonograph to an automatic timer to play Spanish lessons while he sleeps. Steve and Bub ultimately end up sleeping in the room and are able to speak fluent Spanish the following day.
In Anthony Burgess's 1962 novel A Clockwork Orange, it is used to reverse the effects of the Ludovico Technique, a form of conditioning, which was used on the main character Alex to make him incapable of violent behavior. The conditioning was a new technique which was supposed to rehabilitate violent criminals in a short period of time, but which resulted in Alex attempting to commit suicide. This reflected very badly on the government, which had sanctioned the experiment, so hypnopædia was used to undo the conditioning.
In 1954 Günter Spang wrote a children's book called Lohengrin schwant etwas, meaning Lohengrin has a good idea, in which a bunch of schoolchildren take an easy way out of studying by learning in their sleep.
In a 1963 episode of The Patty Duke Show, "The Conquering Hero", Cathy tries to help a failing basketball player pass a quiz. She suggests that the latest scientific method of "subconscious learning" will help. She records the lessons on a tape which plays repeatedly while he is asleep. He passes the quiz after the answers "come to him" while looking at the questions.
In the 1965 episode of "I Spy" titled Chrysanthemum, the assigned partner of Bill Cosby and Robert Culp's characters, Maximilian de Broget claims to have learned Mandarin Chinese in his sleep.
In the 1965 movie The Monkey's Uncle, a college student connects a phonograph to an automatic timer, which plays to sleeping students the voice of a girl reading their lessons aloud. This backfires in class, however—when asked to give an oral report, the students speak, but in the girl's voice.
In the 1966 novel Flowers for Algernon, an intellectually disabled 37-year-old, Charlie Gordon, has an operation to increase his intelligence. Professor Nemur and Dr. Strauss then give Charlie a "teeching mashine that werks like T.V." Charlie explains to Professor Nemur that .
The 1976 film Logan's Run contains a scene where Logan 5 (Michael York) chastises his friend Francis 7 (Richard Jordan) for his rigidly orthodox opinions, "You sound like a sleep-teacher with a stuck tape".
In a 1988 episode of the BBC2 sitcom Red Dwarf, "Me2", Arnold Rimmer uses sleep-learning tapes such as Learn Esperanto While You Sleep and Learn Quantum Theory While You Sleep, to the dismay of his bunkmate Dave Lister.
In the 1990 movie Dragon Ball Z: The Tree of Might, Chi-Chi packs for her son Gohan a tape recorder so he can learn while he sleeps on a camping trip.
In a 1992 episode of The Simpsons, "Bart's Friend Falls in Love", Homer orders hypnosis tapes which are supposed to induce weight loss. However, the mail-order company sends him vocabulary builder tapes instead, and Homer gets fatter and fatter while his vocabulary increases, through hypnopædia.
In a 1996 episode of Dexter's Laboratory, "The Big Cheese", Dexter hooks himself up to a gramophone that repeats his lesson for a French class test the next morning. The gramophone gets stuck at the phrase omelette du fromage, and Dexter finds out the next morning that it is all he is capable of saying.
In a 1997 episode of Friends, "The One with the Hypnosis Tape", Chandler borrows from Rachel a smoking-cessation audiocassette, to which he listens while he is asleep. The tape tells him that he is "a strong, confident woman" who does not need to smoke. He stops smoking, but also begins acting effeminately.
In the 1997 PC game Outpost 2: Divided Destiny, one of the items available for research was hypnopædia, which allowed scientists to be trained more quickly.
In a 2001 episode of Homestar Runner, "A Jorb Well Done", Coach Z attempts to overcome his speech impediment with the word "job" (which he pronounces as "jorb"). After unsuccessfully trying several methods, Strong Sad gives him a tape of him repeating the word job thousands of times, "from when (he) was practicing the dictionary". Coach Z takes it home and listens to it while he sleeps, and the next day is able to pronounce "job" correctly, but forgets Homestar's name.
The twins Hank and Dean Venture, of the animated television program The Venture Bros., are homeschooled through the use of hypnopædic beds.
See also
Educational technology
Mozart effect
Sleep and learning, the science that ties sleep to learning
References
Further reading
Fox, B.H. (1968). Current research in Hypnopaedia. Macdonald & Co. [PDF]
Sleep
Educational technology
Pseudoscience | Sleep-learning | Biology | 1,622 |
8,963,881 | https://en.wikipedia.org/wiki/The%20Hitchhiker%27s%20Guide%20to%20the%20Galaxy%20%28fictional%29 | The Hitchhiker's Guide to the Galaxy is a fictional electronic guide book in the multimedia scifi/comedy series of the same name by Douglas Adams. The Guide serves as "the standard repository for all knowledge and wisdom" for many members of the series' galaxy-spanning civilization. Entries from the guidebook are used as comic narration to bridge events and provide background information in every version of the story. The guide is published by "Megadodo Publications", a publishing company on Ursa Minor Beta, and it is written and edited by many characters throughout the series.
In the original radio scripts, the Guide's voice was called the "Narrator" and in the 2004–2005 series, "The Voice". For all of the radio series and the 1981 TV series, the role was credited as "The Book", though this was changed to "Narrator/The Guide" for the 2005 movie.
In the first two phases of the radio series, the LP album adaptations of the first radio series and in the television series, the Guide was voiced by British actor Peter Jones. During the 2004–2005 radio series, The Guide was voiced by William Franklyn. In the film version, it was voiced by Stephen Fry. In the Hexagonal Phase of the radio series, based on the novel, And Another Thing..., the Guide was voiced by the series co-creator John Lloyd.
Overview
The "wholly remarkable" Guide is described as being Megadodo Publications' most successful book, being more popular than The Celestial Homecare Omnibus, better-selling than 53 More Things To Do in Zero Gravity and more controversial than philosophical author Oolon Colluphid's blockbuster "God Trilogy" (Where God Went Wrong, Some More of God's Greatest Mistakes, and Who is this God Person Anyway?).
It is said to have supplanted the rival Encyclopedia Galactica as a "standard repository of all knowledge and wisdom" in some parts of the galaxy for two reasons, one of them being that has a slightly cheaper price, and the other that it has the words "DON'T PANIC" printed on its cover.
Entries
The Guides numerous entries are quoted throughout the various incarnations of the Hitchhiker's Guide series. As well as offering background information, the Guide's entries often employ irony, sarcasm and subtle commentary on the action and on life in general. For instance, the entry on the Sirius Cybernetics Corporation describes their marketing division as "a bunch of mindless jerks who will be the first against the wall when the revolution comes", with a footnote to the effect that the editors would welcome applications from anyone interested in taking over the post of robotics correspondent. The entry on the villainous Vogons begins, "Here's what to do if you want to get a lift from a Vogon: forget it." The entry on "What to do if you find yourself stuck in a crack in the ground underneath a giant boulder you can't move, with no hope of rescue" suggests that first, you "consider how lucky you are that life has been good to you so far. Alternatively, if life hasn't been good to you so far, which given your current circumstances seems more likely, consider how lucky you are that it won't be troubling you much longer." Its advice on drunkenness is simply, "Go to it, and good luck", and according to the 2005 film, its entry on love is "Avoid, if at all possible".
The Guide tends to focus on certain topics. For instance, if looking for information about sex, the Guide suggests reading "chapters seven, nine, ten, eleven, fourteen, sixteen, seventeen, nineteen, twenty-one to eighty-four inclusive, and in fact most of the rest of the Guide." On the Guide'''s outdated and typo-filled entries (some of which could cause serious injury or death, such as "Ravenous Bugblatter Beasts often make a very good meal for visiting tourists," rather than "Ravenous Bugblatter Beasts often make a very good meal of visiting tourists.") Adams wrote, "...though it cannot hope to be useful or informative on all matters, it does make the reassuring claim that where it is inaccurate, it is at least definitively inaccurate. In cases of major discrepancy it was always reality that's got it wrong."
Editing
Despite the work of dedicated field researchers such as Ford Prefect, many of the contributions to the Guide are made on a strictly ad-hoc basis. With the permanent staff more likely to be on a lunch break than working, "most of the actual work got done by any passing stranger who happened to wander into the empty offices of an afternoon and saw something worth doing." This has led to the Guide being patchy in its coverage, cobbled together (for example: the entry on "The Universe" was copied from the back of a packet of breakfast cereal) and often riddled with errors. The novel of the same name notes that "it has many omissions and contains much that is apocryphal, or at least wildly inaccurate ...."
Although Ford puts together a lengthy and detailed entry on Earth during the 15 years he is stranded there, the editors cut it down to two words: "Mostly harmless." In So Long, and Thanks for All the Fish, he is stunned to see his entire original work restored during a database update, even though he saw the planet being demolished by the Vogons. The change turns out to be necessary because another Earth has been pulled into existence from a parallel universe by dolphins in order to prevent humans from becoming extinct.
The Guide can receive updates to its data base via Sub-Etha. Field researchers (like Ford Prefect) can also use the Guide to edit entries and transmit these back to the publisher.
Publisher
At the start of the series, the Guide was published by Megadodo Publications, one of the "great publishing corporations of Ursa Minor." When Megadodo was bought out by Infinidim Enterprises in Mostly Harmless, the new editor in chief, Vann Harl, changed the Guide's demographic from penniless hitchhikers to families in billions of billions of alternate worlds, thus altering the Guide's original purpose. When Ford learned of this plan, he knocked out Vann Harl and stole his Ident-I-Eeze card to increase the spending limit on Ford's own Dine-O-Charge card. Ford was thus able to use his Dine-O-Charge to buy (among other things): a pink spaceship, all the foie gras in London, and The London Zoo, in addition to buying the hotel he was staying at for the concierge, all charged to the Guide and Infinidim Enterprises.
Physical description
In the radio series, Ford describes the Guide as "a sort of electronic book", with several million entries.
In the first book, Ford's copy of the Guide is described as looking "rather like a largish electronic calculator" and "insanely complicated", with "about a hundred tiny flat press buttons and a screen about four inches square" which could display any of a million pages. The Guide reads its entries aloud in a "still quiet measured voice".
In So Long, and Thanks for All the Fish, Arthur's copy is described as resembling "a small, thin, flexible lap computer" encased in a "sturdy plastic cover" with the words "Don't Panic" inscribed on it "in large, friendly letters". Arthur's copy of the Guide is described as "battered and travelworn" by this point in the series, having survived being thrown into a river, "frozen on the glaciers of the moon of Jaglan Beta, sat on, kicked around spaceships, scuffed and generally abused".
The Guide's entries are arranged alphabetically on the screen and accessed via typing entry codes on a keyboard; "Earth" is on the same page as "Eccentrica Gallumbits, the Triple-Breasted Whore of Eroticon 6." In So Long, and Thanks for All the Fish the Guide's "current tally" of pages is said to be 5,975,509.
In the film, the Guide is depicted as a large metal book with a large screen instead of pages. This incarnation's entries are reached by voice activation (in the only example of this being shown, saying the word "Vogon" brought up the article on Vogons.)
Personality
At the start, the Guide is merely an information resource, although one with a distinctly flippant and exuberant tone. Its introduction begins with the words, "Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean you may think it's a long walk down the road to the chemist, but that's just peanuts to space. Listen..." However, in the fifth novel, Mostly Harmless, a new edition of the Guide, the Guide Mark II, is published that is artificially intelligent and capable of interacting with the reader. This Guide, which takes the form of a black, birdlike robot, appears pleasant and friendly but is in fact deeply malevolent and in league with the Vogons in a plot to destroy Earth. Strangely enough, it saves all the main characters from certain doom as part of some unknown agenda and disappears from existence shortly before the Grebulons destroy Earth at the beginning of the sixth book in the series, And Another Thing by Eoin Colfer.
Representation
In the original radio series, Peter Jones provided the voice for "The Book" as both the Guide itself and as the overall narrator. When speaking as the Guide, Jones's voice was electronically filtered to sound mechanical, and spoken against simple electronic music. When speaking merely as the narrator, his voice was left unfiltered.
In the television series, Jones's voice was left unfiltered for both the Guide and "general" narrations, which were accompanied by hand-drawn animations representing computer readouts. These animations often contained little jokes, such as the full text of the "worst poetry in the universe", the equation of 37 Earth miles as "1 Altairian long way", the inclusion of a topping of meringue on a Magrathea-constructed planet, and the outcome of an intergalactic war represented as a video game score.
The 2005 film, which featured Stephen Fry as the narrator/Guide, also employed animations, but in a more minimalist, abstract style. They were animated by Shynola.
An illustrated 42nd anniversary edition of the book featured illustrations by Chris Riddell, often used to accompany Guide entries.
Inspiration
Adams conceived of the Guide while hitchhiking from London to Istanbul in 1971. Drunk and penniless in a field in Innsbruck, Austria, Adams looked up at the stars and then at his stolen copy of Hitch-hiker's Guide to Europe and thought that someone should write The Hitchhiker's Guide to the Galaxy. The Hitch-hiker's Guide to Europe claimed in its introduction that it was possible to survive in Europe on less than US$25 a week, a claim echoed in the catchphrase of the Hitchhiker's Guide to the Galaxy that it was the best source of advice for those who wanted to see the universe "on less than 30 Altairian dollars a day."
In reality
Douglas Adams, who was deeply involved with computer technology, founded the website h2g2 in 1999. In keeping with the Hitchhiker's Guides tradition of being edited by random people off the street, h2g2 is an encyclopedia edited by thousands of contributors. The site's creation predates Wikipedia by two years, though several commentators have noted the similarities between Wikipedia and the Hitchhiker's Guide, particularly its wild variance in reliability and quality and its tendency to focus on topics of interest to its writers.
In 2000 Adams wrote:
Some have compared Apple's iPad and Amazon's Kindle to the Hitchhiker's Guide; indeed fans have designed "Don't Panic" covers for both.
Combining tablets or e-readers with Wikipedia is often considered the closest existing equivalent to the Hitchhiker's Guide to date. An app for the iPad allows users to read Guide entries as they appeared in the various Hitchhikers media.
See also
Encyclopedia Galactica''
References
The Hitchhiker's Guide to the Galaxy
Fictional books
Fictional encyclopedias
Fictional artificial intelligences
Fictional computers
Interstellar communication | The Hitchhiker's Guide to the Galaxy (fictional) | Technology | 2,615 |
216,159 | https://en.wikipedia.org/wiki/Chemical%20waste | Chemical waste is any excess, unused, or unwanted chemical. Chemical waste may be classified as hazardous waste, non-hazardous waste, universal waste, or household hazardous waste, each of which is regulated separately by national governments and the United Nations. Hazardous waste is material that displays one or more of the following four characteristics: ignitability, corrosivity, reactivity, and toxicity. This information, along with chemical disposal requirements, is typically available on a chemical's Safety Data Sheet (SDS). Radioactive and biohazardous wastes require additional or different methods of handling and disposal, and are often regulated differently than standard hazardous wastes.
Laboratory chemical waste in the US
The U.S. Environmental Protection Agency (EPA) prohibits disposing of certain materials down drains. Therefore, when hazardous chemical waste is generated in a laboratory setting, it is usually stored on-site in appropriate waste containers, such as triple-rinsed chemical storage containers or carboys, where it is later collected and disposed of in order to meet safety, health, and legislative requirements. Many universities' Environment, Health, and Safety (EHS) divisions/departments serve this collection and oversight role.
Organic solvents and other organic waste is typically incinerated. Some chemical wastes are recycled, such as waste elemental mercury.
Laboratory waste containment
Packaging
During packaging, chemical liquid waste containers are filled to no greater than 75% capacity to allow for vapor expansion and to reduce potential spills that can occur from transporting or moving overfilled containers. Containers for chemical liquid waste are typically constructed from materials compatible with the hazardous waste being stored, such as inert materials like polypropylene (PP) or polytetrafluoroethylene (PTFE). These containers are also constructed of mechanically robust materials in order to minimize leakage during storage or transit.
In addition to the general packaging requirements mentioned above, precipitates, solids, and other non-fluid wastes are typically stored separately from liquid waste. Chemically contaminated glassware is disposed of separately from other chemical waste in containers that cannot be punctured by broken glass.
Labelling
Containers may be labelled with the group name from a list of chemical waste categories, along with an itemized list of the contents. All chemicals or materials contaminated by chemicals pose a significant hazard, and as such regulations require that the identity of the chemicals in a waste container is obvious.
Storage
Chemical waste containers are kept closed to prevent spillage, except when waste is being added. Suitable containers are labeled in order to inform disposal specialists of the contents as well as to prevent the addition of incompatible chemicals. Liquid waste is stored in containers with secure screw-top or similar lids that cannot be easily dislodged in transit. Solid waste is stored in various sturdy, chemically inert containers, such as large, sealed buckets or thick plastic bags. Secondary containment, such as trays or safety cabinets, are used to capture spills and leaks from the primary container and to segregate incompatible hazardous wastes, such as acids and bases.
Chemical compatibility guidelines
Many chemicals react adversely when combined. Incompatible chemicals are therefore stored in separate areas of laboratories.
Acids are separated from alkalis, metals, cyanides, sulfides, azides, phosphides, and oxidizers, as when acids combine with these types of compounds, violent exothermic reactions can occur. In addition, some of these reactions produce flammable gases, which, combined with the heat produced, may cause explosions. In the case of cyanides, sulfides, azides, phosphides, etc. Toxic gases are also produced.
Oxidizers are separated from acids, organic materials, metals, reducing agents, and ammonia, as when oxidizers combine with these types of compounds, flammable and sometimes toxic compounds can be created. Oxidizers also increase the likelihood that any flammable material present will ignite, seen most readily in research laboratories with improper storage of organic solvents.
Environmental pollution
Pharmaceuticals
PPCPs
River pollution
Textile industry
The textile industry is one of the largest polluters in the globalized world of mostly free market dominated socioeconomic systems. Chemically polluted textile wastewater degrades the quality of the soil and water. The pollution comes from the type of conduct of chemical treatments used e.g., in pretreatment, dyeing, printing, and finishing operations that many or most market-driven companies use despite "eco-friendly alternatives". Textile industry wastewater is considered to be one the largest polluters of water and soil ecosystems, causing "carcinogenic, mutagenic, genotoxic, cytotoxic and allergenic threats to living organisms". The textile industry uses over 8000 chemicals in its supply chain, also polluting the environment with large amounts of microplastics and has been identified in one review as the industry sector producing the largest amount of pollution.
A campaign of big clothing brands like Nike, Adidas and Puma to voluntarily reform their manufacturing supply chains to commit to achieving zero discharges of hazardous chemicals by 2020 (global goal) appears to have failed.
The textile industry also creates a lot of pollution that leads to externalities which can cause large economic problems. The problem usually occurs when there is no division of ownership rights. This means that the problem of pollution is largely caused because of incomplete information about which company pollutes and at what scale the damage was caused by the pollution.
Planetary boundary
A study by "Scienmag" defines a 'planetary boundary' for novel entities such as plastic and chemical pollution. The study reported that the boundary has been crossed.
Regulation of chemical waste
Chemicals waste may fall under regulations such as COSHH in the United Kingdom or the Clean Water Act and Resource Conservation and Recovery Act in the United States. In the U.S., the Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA), as well as state and local regulations, also regulate chemical use and disposal.
Chemical waste in Canadian aquaculture
Chemical waste in oceans is becoming a major issue for marine life. There have been many studies conducted to try and prove the effects of chemicals in oceans. In Canada, many of the studies concentrated on the Atlantic provinces, where fishing and aquaculture are an important part of the economy. In New Brunswick, a study was done on sea urchins in an attempt to identify the effects of toxic and chemical waste on life beneath the ocean, specifically the waste from salmon farms. Sea urchins were used to check the levels of metals in the environment. Green sea urchins have been used as they are widely distributed, abundant in many locations, and easily accessible. By investigating the concentrations of metals in the green sea urchins, the impacts of chemicals from salmon aquaculture activity could be assessed and detected. Samples were taken at 25-meter intervals along a transect in the direction of the main tidal flow. The study found that there were impacts to at least 75 meters based on the intestine metal concentrations.
See also
Industrial waste
List of waste types
Municipal solid waste
Radioactive waste
Toxic waste
Waste management
Water pollution
References
Further reading
External links
Industrial Materials Recycling – US EPA
Waste
Water pollution | Chemical waste | Physics,Chemistry,Environmental_science | 1,480 |
33,842,805 | https://en.wikipedia.org/wiki/Sampling%20%28medicine%29 | In medicine, sampling is gathering of matter from the body to aid in the process of a medical diagnosis and/or evaluation of an indication for treatment, further medical tests or other procedures. In this sense, the sample is the gathered matter, and the sampling tool or sampler is the person or material to collect the sample.
Sampling is a prerequisite for many medical tests, but generally not for medical history, physical examination and radiologic tests.
By sampling technique
Obtaining excretions or materials that leave the body anyway, such as urine, stool, sputum, or vomitus, by direct collection as they exit. A sample of saliva can also be collected from the mouth.
Excision (cutting out), a surgical method for the removal of solid or soft tissue samples.
Puncture (also called centesis) followed by aspiration is the main method used for sampling of many types of tissues and body fluids. Examples are thoracocentesis to sample pleural fluid, and amniocentesis to sample amniotic fluid. The main method of centesis, in turn, is fine needle aspiration, but there are also somewhat differently designed needles, such as for bone marrow aspiration. Puncture without aspiration may suffice in, for example, capillary blood sampling.
Scraping or swiping. In a Pap test, cells are scraped off a uterine cervix with a special spatula and brush or a special broom device that is inserted through a vagina without having to puncture any tissue. Epithelial cells for DNA testing can be obtained by swiping the inside of a cheek in a mouth with a swab.
Biopsy or cytopathology
In terms of sampling technique, a biopsy generally refers to a preparation where the normal tissue structure is preserved, availing for examination of both individual cells and their organization for the study of histology, while a sample for cytopathology is prepared primarily for the examination of individual cells, not necessarily preserving the tissue structure. Examples of biopsy procedures are bone marrow biopsy, brain biopsy, skin biopsy and liver biopsy.
By sampled matter
Different types of matter that are sampled can be categorized by solidness versus fluidity, such as:
Solid tissue, such as in bone marrow biopsy
Soft tissue, such as in a muscle biopsy
Body fluids such as blood
Body fluid sampling
Body fluid sampling includes:
Blood sampling for any blood test, including:
Arterial blood sampling, such as by radial artery puncture. This can be done for arterial blood gas analysis.
Capillary blood sampling, generally by using a blood lancet for puncture, followed by sampling by capillary action with a test strip or small pipe. This is common for routine diabetic monitoring for glucose.
Venous blood sampling, also called phlebotomy. It is generally done by venipuncture (which can also be used for intravenous therapy). Other than routine diabetic monitoring for glucose, the majority of blood tests are done on samples of venous blood taken by a health professional, including phlebotomists who are specifically trained in venipuncture. Such samples are commonly collected in capped test tubes, often with a small amount of some sort of preservative.
Cerebrospinal fluid sampling, generally by lumbar puncture
Pleural fluid sampling, generally by thoracocentesis
Amniotic fluid sampling, generally by amniocentesis
Peritoneal fluid sampling, generally by peritoneocentesis (also called laparocentesis). It can be used for cytology to detect spread of gynecologic cancers.
By component of interest
The sampled matter can be analyzed for various components, for example:
Electrolytes
Proteins
cells, such as white blood cells in blood sampling
Microbiological agents, such as bacteria or fungi
Microbiological sampling
Microbiological sampling include:
Blood sampling for blood cultures, performed similarly as that for tests on the fluid itself above
Throat swab for throat culture. It is performed by applying a cotton swab to the surface of the throat.
Sampling of sputum from the lungs for sputum culture. It can be performed by special techniques of coughing, or by a protected specimen brush (PSB), which is a brush that can be retracted into a plastic tube to prevent contamination of bacteria in the throat while inserting and removing the instrument.
References
Biological techniques and tools
Biological specimens | Sampling (medicine) | Biology | 916 |
26,092,568 | https://en.wikipedia.org/wiki/Plan%20Calcul | Plan Calcul was a French governmental program to promote a national or European computer industry and associated research and education activities.
History
The plan was approved in July 1966 by President Charles de Gaulle, in the aftermath of two key events that made his government worry about French dependence on the US computer industry. In the mid-1960s, the United States denied export licenses for American-made IBM and CDC computers to the French Commissariat à l'énergie atomique in order to prevent it from perfecting its H bomb. Meanwhile, in 1964, General Electric had acquired a majority of Compagnie des Machines Bull, the largest French computer manufacturer, which had the second highest market share in France, after IBM, and was a leading IT equipment maker in Europe. Following this partial takeover, known as "Affaire Bull", GE-Bull dropped two Bull computers from its product line.
Responsibility for administering the plan was given to a newly created government agency, (Information Bureau), answering directly to the prime minister.
Compagnie Internationale d'Informatique
As part of the program, in December 1966, the Compagnie Internationale d'Informatique (CII) was established as a manufacturer of commercial and scientific computers, initially under licence from Scientific Data Systems. The new company was intended to compete not only in the process control and military market, where its staff was already seasoned, but also in the office computing sector of the French market, where IBM and Bull were dominant at the time. The plan enacted government subsidies for CII between 1967 and 1971, and was reconducted for another four years. A minor side of the plan was devoted to peripherals, while CII's main parent company, Thomson-CSF, received government support to develop its semiconductor plants and R & D. Overall, while CII mainframes benefitted from preferential procurement by the French government, the Plan Calcul left peripherals, components and small computers makers compete on the free market. The same went for software companies, which were already thriving in France.
On the research side, the program also led to the creation of L'Institut de recherche en informatique et en automatique (IRIA) in 1967, which later became INRIA. It was accompanied with a vast educational effort in programming and computer science.
In the late 1960s, CII announced its new, internally designed mainframes Iris 50 [1970] and Iris 80 [1971], and developed a mini-computer, Mitra 15 (1971), which became a commercial success in the following decade. The company also was a minority participant in the production of magnetic peripherals thru part ownership of Magnetic Peripherals Inc.
IBM had more than 50% market share in almost every European country. Information Bureau head warned that international cooperation was necessary, however, as "something must happen or there won't be a European computer industry". The French government had spent more than $100 million on Plan Calcul in the first five years, and planned to spend more than that amount in the next five. France expected CII to reach $200 million in revenue before 1975. That year, CII began negotiations with Siemens and Philips to form a joint European company, Unidata, which shipped its first computers in 1974. Yet a new President of the Republic was elected then, former Finance minister Giscard d'Estaing, who was a strong opponent of the Plan Calcul; meanwhile, CII's sleeping partner, CGE-Alcatel, woke up to oppose the domination of its archrival Siemens over the European computer industry. Unidata was terminated and CII was absorbed into Honeywell-Bull in 1976.
This government initiative was ultimately deemed a failure.
See also
References
History of computing in France
Politics of France
Science and technology in France
1966 in France
Computer-related introductions in 1966
Presidency of Charles de Gaulle | Plan Calcul | Technology | 802 |
4,538,295 | https://en.wikipedia.org/wiki/Australian%20Synchrotron | The Australian Synchrotron is a 3 GeV national synchrotron radiation facility located in Clayton, in the south-eastern suburbs of Melbourne, Victoria. The facility opened in 2007, and is operated by the Australian Nuclear Science and Technology Organisation.
ANSTO's Australian Synchrotron is a light source facility (in contrast to a collider), which uses particle accelerators to produce a beam of high energy electrons that are boosted to nearly the speed of light and directed into a storage ring where they circulate for many hours or even days at a time. As the path of these electrons are deflected in the storage ring by either bending magnets or insertion devices, they emit synchrotron light. The light is channelled to experimental endstations containing specialised equipment, enabling a range of research applications including high resolution imagery that is not possible under normal laboratory conditions.
ANSTO's Australian Synchrotron supports the research needs of Australia's major universities and research centres, and businesses ranging from small-to-medium enterprises to multinational companies. During 2014–15 the Australian Synchrotron supported more than 4,300 researcher visits and close to 1,000 experiments in areas such as medicine, agriculture, environment, defence, transport, advanced manufacturing and mining.
In 2015, the Australian Government announced a ten-year, million investment in operations through ANSTO, Australia's Nuclear Science and Technology Organisation . A 1.5 MW solar power system on the roof is expected to save $2 million in electricity costs over 5 years.
In 2020, it was used to help map the molecular structure of the COVID-19 virus, during the COVID-19 pandemic.
Accelerator systems
Electron gun
The electrons used to provide the synchrotron light are first produced at the electron gun, by thermionic emission from a heated metal cathode. The emitted electrons are then accelerated to an energy of 90 keV (kilo-electron volts) by a 90 kilovolt potential applied across the gun and make their way into the linear accelerator.
Linear accelerator
The linear accelerator (or linac) uses a series of RF cavities, operating at a frequency of 3 GHz, to accelerate the electron beam to an energy of 100 MeV, over a distance of around 15 metres. Due to the nature of this acceleration, the beam must be separated into discrete packets, or 'bunches'. The bunching process is done at the start of the linac, using several 'bunching' cavities. The linac can accelerate a beam once every second. Further along the linac quadrupole magnets are used to help focus the electron beam.
Booster synchrotron
The booster is an electron synchrotron which takes the 100 MeV beam from the linac and increases its energy to 3 GeV. The booster ring is 130 metres in circumference and contains a single 5-cell RF cavity (operating at 500 MHz) which provides energy to the electron beam. Acceleration of the beam is achieved by a simultaneous ramping up of the magnet strength and cavity fields. Each ramping cycle takes approximately 1 second (for a complete ramp up and down).
Storage ring
The storage ring is the final destination for the accelerated electrons. It is 216 metres in circumference and consists of 14 nearly identical sectors. Each sector consists of a straight section and an arc, with the arcs containing two dipole 'bending' magnets each. Each dipole magnet is a potential source of synchrotron light and most straight sections can also host an insertion device, giving the possibility of 30+ beamlines at the Australian Synchrotron. Two of the straight sections are used to host the storage ring 500 MHz RF cavities, which are essential for replacing the energy that the beam loses through synchrotron radiation. The storage ring also contains a large number of quadrupole and sextupole magnets used for beam focusing and chromaticity corrections. The ring is designed to hold 200 mA of stored current with a beam lifetime of over 20 hours.
Vacuum systems
The electron beam is kept within a very high vacuum at all times during the acceleration process and within the storage ring. This vacuum is necessary as any beam collisions with gas molecules will quickly degrade the beam quality and reduce the lifetime of the beam. The vacuum is achieved by enclosing the beam in a stainless steel pipe system, with numerous vacuum pump systems continually working to keep the vacuum quality high. Pressure within the storage ring is typically around 10−13 bar (10 nPa).
Control system
Each digital and analogue I/O channel is associated with a database entry in a customised distributed open source database system called EPICS (Experimental Physics and Industrial Control System).
The condition of the system is monitored and controlled by connecting specialised GUIs to the specified database entries.
There are about 171,000 database entries (also known as process variables), many of which relate to the physical I/O. About 105,000 of these are permanently archived at intervals ranging from tenths of a seconds to minutes.
Some high level control of the physics-related parameters of the beam is provided through MATLAB which also provides data analysis tools and an interface with a computerised model of the accelerator.
Personnel and equipment protection is achieved through the use of PLC-based systems, which also transfer data to EPICS.
The Beamlines also use EPICS as the basis for their control.
Australian Synchrotron beamlines
Imaging and Medical Beamline (IMBL)
X-ray Fluorescence Microscopy (XFM) beamline
Macromolecular and Micro crystallography (MX1 and MX2) beamlines (Protein crystallography)
Infrared microscopy (IRM) beamline
Far Infrared, THz Spectroscopy (THz) beamline
Soft X-ray Spectroscopy (SXR) beamline
Small and Wide Angle X-ray Scattering (SAXS/WAXS) beamline
X-ray Absorption Spectroscopy (XAS) beamline
Powder diffraction (PD) beamline
Micro Computed Tomography (MCT)
Medium Energy X-ray Absorption Spectroscopy (MEX1 and MEX2)
Beamlines under construction (as of 2023)
Biological Small Angle Scattering (BioSAXS)
Advanced Diffraction and Scattering (ADS1 and ADS2)
X-ray Fluorescence NanoProbe (Nano)
High Performance Macromolecular Crystallography (MX3)
See also
List of synchrotron radiation facilities
References
External links
Australian Synchrotron website
Facility Status software – updated every minute
ANSTO, Australia's Nuclear Science and Technology Organisation website
Lightsources – website about the world's synchrotrons
'The Australian Synchrotron is great... but what does it do?' at The Conversation, March 2012.
Deconstruction of Australian Synchrotron in symmetry magazine (Fermilab/SLAC), May 2006
Research institutes in Australia
Synchrotron radiation facilities
Monash University
2007 establishments in Australia
Buildings and structures in the City of Monash
Research institutes established in 2007 | Australian Synchrotron | Materials_science | 1,453 |
20,344,376 | https://en.wikipedia.org/wiki/Social%20presence%20theory | Social presence theory explores how the "sense of being with another" is influenced by digital interfaces in human-computer interactions. Developed from the foundations of interpersonal communication and symbolic interactionism, social presence theory was first formally introduced by John Short, Ederyn Williams, and Bruce Christie in The Social Psychology of Telecommunications. Research on social presence theory has recently developed to examine the efficacy of telecommunications media, including SNS communications. The theory notes that computer-based communication is lower in social presence than face-to-face communication, but different computer-based communications can affect the levels of social presence between communicators and receivers.
Origins
The concept of social presence originated from Morton Wiener and Albert Mehrabian's study of immediacy and Michael Argyle and Janet Dean's concept of intimacy. Wiener and Mehrabian identified immediacy as nonverbal communication behaviors such as eye contact and body movements that can enhance closeness in interactions. Argyle and Dean noted intimacy as a combination of eye contact, physical proximity, and smiling.
The U.K.'s post office first funded Short et al.'s work in an attempt to observe customer's attitudes towards different media channels.
Social Presence Theory is defined by the different apparent physical proximities produced by various media, the two more popular media being face-to-face communication and online interaction. Social presence is measured by the ability to project physical and emotional presence and experience it from others in interactions. Effective communication is measured by the parties' interpersonal involvement while considering the constraints of the communication medium used.
Definitions of social presence are inconsistent, as scholars attempt to pinpoint what the phenomenon encompasses, and how it can be adapted as new media of interpersonal communication arise. Social Presence in recent years has been defined as the feeling of community a learner experiences in an online environment. We have developed multiple non-verbal intimacy behaviors in the online community that enhance our relationships with people when we communicate in a medium where there is no real-life contact.
Additional Research
Patrick R. Lowenthal noted that concepts of social presence fall on a spectrum between users' perceptions of a person being real or "being there" and whether two communicators experience positive interpersonal and emotional connections between each other. Lowenthal believes that most researchers tend to fall somewhere on the spectrum between those two perceptions.
Other research has defined social presence as the awareness of others in an interaction, combined with an appreciation of the interpersonal aspects of that interaction. In 1995, Gunawardena argued that social presence varied with perception and was a subjective issue based upon objective qualities. We are social beings, and we crave socialization, and social presence explains how we form relationships and how beneficial and necessary they are to our lives.
The definitions and interpretations of social presence—given by multiple sources after the original work conducted by Short, Williams, and Christie—have offered a more unobstructed view that Social Presence is more of a combination of factors that present themselves in a way so as to develop greater intimacy within a group that has a positive effect on the individual's affective filters. Several researchers have suggested that intimacy and immediacy are contributing factors to Social Presence with intimacy defined as a measure of communication involving eye contact, proximity and body language and immediacy defined as the psychological distance between two parties that is conveyed through verbal and nonverbal cues in speech.
Chih-Hsiung Tu said that Short et al.'s definition was not satisfactory because it did not include all components of social presence. He also said that the theory did not address enough degrees of social presence in computer-mediated communications.
In 2000–2001, Tu argued that within distance learning, social presence rests upon three dimensions: social context, online communication, and interactivity. Social contexts contribute to a predictable degree of perceived social presence. Social contexts involve task orientation and privacy, topics, social relationships, and social process. A closely related theory, electronic propinquity, also examines this quality of human connection through technology.
Classification of media
Social Presence Theory classifies different communication media on a one-dimensional continuum of social presence, where the degree of social presence is equated to the degree of awareness of the other person in a communication interaction.
Social Presence Theory in communication is effective if the communication medium has the appropriate social presence required for the level of interpersonal involvement required in an engagement, which is one of the challenges communicators have at the time of engaging their audience.
On a continuum of social presence, the face-to-face medium is considered to have the most social presence; and written, text-based communication the least. Inter-party and interpersonal exchanges are two aspects of interactions identified by Short, Williams, and Christie. It is assumed in Social Presence Theory that in any interaction involving two parties, both parties are concerned with acting out certain roles and developing or maintaining some sort of personal relationship.
Face-to-face interactions
The most basic of interactions are done face-to-face; and the participants exchange, in addition to verbal communication, a set of non-verbal cues, such as facial expression, direction of gaze, posture, dress, and body language. In the work about Kinesics done by Birdwhistell in 1970, there were two types of functions identified for non-verbal cues. One of the functions is directly related to the message that is being sent from one individual to another is concerned with the communication process and the integrational aspects.
The integrational activity includes the behavior that keeps the interaction in process, and the comprehensibility that goes in the exchange between individuals. Argyle, in 1969, identified the functions of six non-verbal cues and the role they play in the communications process. There are three that are integrational and three that are informational.
The integrational functions are:
Mutual attention and responsiveness: eye-gaze, head nods, and gestures.
Channel control: head nods and eye movements.
Feedback: This is mainly for the speaker to know how the audience is receiving the message.
The informational functions are:
Illustrations: Hand gestures to paint a picture or an object.
Emblems: Gestures being used instead of a word, like moving your head up and down to signify "yes."
Interpersonal attitudes: eye-gaze, gestures, proximity, and facial expressions.
Computer-mediated interactions
As computer-mediated communication has evolved, a more relational view of social presence has emerged. Social presence has come to be viewed as the way individuals represent themselves in their online environment. It's a personal stamp that indicates that the individual is available and willing to engage and connect with other persons in their online community. Social presence is demonstrated by the way messages are posted and how those messages are interpreted by others. Social presence defines how participants relate to one another, which in turn affects their ability to communicate effectively.
Social Presence Theory provides a foundation for communication systems designers and serves as a main principle in computer-mediated-communication studies. Gorham & Cristophel (1990), Tu & McIsaac (2002), and Aragon (2003) place high importance on using engagement tactics, in online classrooms, geared towards increasing social presence and reducing distance. These tactics include humanizing the interactions between instructor and students. Asynchronous (pre-produced content accessed individually by students on the web) and synchronous (real-time, simultaneous live connections of students together) components combined can enliven online interactions. Depending on the technology used, synchronous sessions can provide both audio and video connections, allowing an interchange involving both sight and sound, and all the rich nonverbal communication inherent in tone of voice and facial expressions. In a more recent study with distance learning, it is argued that distance learning works strictly to teach academic skill and that face-to-face learning teaches more well rounded skill. Author Jennifer J. Roberts' research discusses a blend of the two teaching mediums and their importance. Brian E. Mennecke, et al., examined how online mediums affect the communication between educators and their students. They discovered an absence of consistent social cues which resulted in their emphasizing a more personal approach to communicating, with added significance placed on the cultural perspectives of the students and how they communicate in an online environment.
Designers have accepted Social Presence Theory as a major design principle, to gain insight into user behavior when developing web-based applications and social computing technologies. They use social communication tools to enhance the student experience and to overcome the challenges of forming interpersonal relationships in a virtual space. Designers seek to provide a high-quality experience for the users by encouraging meaningful interactions between users and the development of interpersonal relationships. In a study conducted by Jahng and Littau in 2016, it was found that the importance we give to computer-mediated communications in order to trust the people we communicate with is reinforced. Their study describes how important it is for journalists to be active on social media in order to create a bond of trust with their audiences. Individuals do not feel comfortable when professionals are not as active on social platforms as is the established norm. Joshua Weidlich, et al., write that every medium can be identified by how genuine are the emotions that are felt by the receiver when the subject communicates emotions both verbally and non verbally.
Research related to the importance of social presence to the success of students points to the need to design social communication tools to enhance users' experience of one another. Social presence affects different aspects of a learner's experience, such as their "success (Russo & Benson, 2005; Zhan & Mei, 2013), satisfaction (Gunawardena & Zittle, 1997; Richardson & Swan, 2003; So & Brush, 2008; Zhan & Mei, 2013), and performance (Lomicka & Lord, 2007; Richardson & Swan, 2003)." A positive social presence enables students to engage with each other with ease, while a negative social presence has been shown to increase disappointment in users, which decreases cognition and familiarity with the material. Without social presence learning interaction suffers, which has negative effects on learning performance. Patrick Lowenthal discussed future trends in online learning with social presence theory in mind. He stated "researchers and practitioners alike will have to consider a new host of things related to social presence with the continued blurring of boundaries between classroom and fully online courses as well as between course bound communication tools (e.g., discussion forums) and non-course bound tools (e.g., Facebook and Twitter)...."
Significance
Social presence is critical in improving instructional effectiveness in any setting, especially in distance education. In 2000–2001, Tu argued that within distance learning, social presence has three dimensions: social context, online communication, and interactivity. Social contexts contribute to a predictable degree of perceived social presence. Social contexts involve task orientation, privacy, topics, social relationships, and social process. As an example, when a conversation is task-based and public without a sense of community being in place, the perception of social presence is low and affective filtering (a communication blockage brought about by negative emotional feelings) is high. In addition, research sheds light on the relationship between a shared learning space and participants' satisfaction and encourages the building up of a shared learning space for a better e-learning environment.
Recent research highlights the importance of social presence in educational settings when delivering feedback on marked assessments.
Measurement
There are three common forms of measuring social presence:
The Social Presence Scale (SPRES), created by Charlotte Gunawardena and Frank Zittle, consists of 14 Likert items to indicate users' perceived social presence.
The Social Presence and Privacy Questionnaire (SPPQ), designed by Chih-Hsiung Tu, distinguished social context, online communication, and interactivity based on a CMC attitude instrument and perceived privacy. However, Tu acknowledged that future work needs to improve the validity of the research.
Karel Kreijns, Paul A. Kirschner, Wim Jochems, and Hans van Buuren developed a self-reporting Social Presence Scale, consisting of five items:
Conclusion
In 1986, Steinfield found that task complexity, interdependence, uncertainty, and the perceived need to communicate over distances were positively associated with increasing online communication. In 1992, Walther argued that social relationships could stimulate changes in discourse as well. In examining text-based computer-mediated communication (e-mails) of conference participants, Walther discovered participants formed impressions of other participants from their communications. These impressions developed into visual interpretations of the other, and a sense of intimacy and identification between participants, which led to greater perception of social presence.
In 1991, Gunawardena argued that a purely text-based communication system (e-mail, discussion boards, and chat) rests upon the assumption that people using such a system have already developed a level of comfort with the technology that allows the person to effectively use it. Gunawardena argued further that text-based communications should account for not all users having a level of comfort in its use. Courses or conferences that rely heavily on such a system for communication should begin with light and casual conversation in areas that the user has familiarity with, which helps them in gaining a comfort level with the technology. Later work by Palloff and Pratt, in 1999 and 2003, validated Gunawardena's recommendation, and they called for establishing learning communities among online users at the very beginning of courses. In doing so, Palloff and Pratt argued that affective filters are lowered.
Interactivity involves the activities and communication styles that online users engage in. In 1986, Norton identified eleven communication styles that can be associated with online communications: impression-leaving, contentious, open, dramatic, dominant, precise, relaxed, friendly, attentive, animated, and image. What style participants use in communicating, especially the style teachers use, will impact social presence.
In their 2002 study on social presence, Tu and McIssac declared, "Social presence positively influences online instruction; however, frequency of participation does not represent high Social Presence". In both a quantitative and qualitative analysis of the interactions of 51 volunteers, Tu and McIssac found that social context was more qualitative (a learned skill-set rather than a prescriptive set of actions) to achieve positive impact, online communication was more strongly related to quantifiable and organizational skills of participants, and that interactivity constituted skill sets and communication styles used in combination. As a result, Tu and McIssac identified the following variables that had strong positive effects on the fueling or perception of social presence.
While research in social presence is ongoing, researchers are confidently recommending designing online and e-format courses along the three dimensions that have been discussed. By building trust online, providing social "hand holding" support up front in any course using computer-mediated communication, and promoting informal relationships, teachers and instructors can provide a strong sense of social presence, increase a sense of community, and in turn increase interaction among participants.
See also
Communication theory
Emotions in virtual communication
Hyperpersonal model
Media naturalness theory
Social identity model of deindividuation effects (SIDE)
Social information processing theory
Computers are social actors
Social translucence
Theories of technology
Kinesics
The Naked Sun
Group think
Ederyn Williams
Isaac Asimov
Online Communication
Michael Argyle
Communication theory
Multicommunicating
Invitational rhetoric
Social information processing theory
Computers are social actors
Computer-Mediated Communication
Media Richness Theory
Persuasion
References
Sources
Argyle, M (1969). Social Interaction. London: Methuen.
Birdwhistell, R.L. (1970). Kinesics and Context. Philadelphia: University of Philadelphia Press.
Palloff, R. M., Pratt, K. (1999). Building learning communities in cyberspace: Effective strategies for the online classroom. San Francisco: Jossey-Bass.
Palloff, R. M., Pratt, K. (2003). The virtual student. San Francisco: Jossey-Bass.
Roberts, J. J. (2019). Online learning as a form of distance education : linking formation learning in theology to the theories of distance education. Hts : Theological Studies, 75(1), 1–9. https://doi.org/10.4102/hts.v75i1.5345.
Services, A. T. (2018, September 27). Social Presence Theory (PDF) . Retrieved from Memorial Library.
Short, J. A., Williams, E., & Christie, B. (1976). The social psychology of telecommunications. London: Wiley.
Wiener, M., & Mehrabain, A. (1968). Language within language: Immediacy, a channel in verbal communication. New York; Appleton-Century-Crofts.
External links
Social Presence theory article at the University of Twente
Mass media technology
Virtual reality | Social presence theory | Technology | 3,455 |
22,810,211 | https://en.wikipedia.org/wiki/Kostant%20polynomial | In mathematics, the Kostant polynomials, named after Bertram Kostant, provide an explicit basis of the ring of polynomials over the ring of polynomials invariant under the finite reflection group of a root system.
Background
If the reflection group W corresponds to the Weyl group of a compact semisimple group K with maximal torus T, then the Kostant polynomials describe the structure of the de Rham cohomology of the generalized flag manifold K/T, also isomorphic to G/B where G is the complexification of K and B is the corresponding Borel subgroup. Armand Borel showed that its cohomology ring is isomorphic to the quotient of the ring of polynomials by the ideal generated by the invariant homogeneous polynomials of positive degree. This ring had already been considered by Claude Chevalley in establishing the foundations of the cohomology of compact Lie groups and their homogeneous spaces with André Weil, Jean-Louis Koszul and Henri Cartan; the existence of such a basis was used by Chevalley to prove that the ring of invariants was itself a polynomial ring. A detailed account of Kostant polynomials was given by and independently as a tool to understand the Schubert calculus of the flag manifold. The Kostant polynomials are related to the Schubert polynomials defined combinatorially by for the classical flag manifold, when G = SL(n,C). Their structure is governed by difference operators associated to the corresponding root system.
defined an analogous basis when the polynomial ring is replaced by the ring of exponentials of the weight lattice. If K is simply connected, this ring can be identified with the representation ring R(T) and the W-invariant subring with R(K). Steinberg's basis was again motivated by a problem on the topology of homogeneous spaces; the basis arises in describing the T-equivariant K-theory of K/T.
Definition
Let Φ be a root system in a finite-dimensional real inner product space V with Weyl group W. Let Φ+ be a set of positive roots and Δ the corresponding set of simple roots. If α is a root, then sα denotes the corresponding reflection operator. Roots are regarded as linear polynomials on V using the inner product α(v) = (α,v). The choice of Δ gives rise to a Bruhat order on the Weyl group
determined by the ways of writing elements minimally as products of simple root reflection. The minimal length for an element s is denoted
. Pick an element v in V such that α(v) > 0 for every positive root.
If αi is a simple root with reflection operator si
then the corresponding divided difference operator is defined by
If and s has reduced expression
then
is independent of the reduced expression. Moreover
if and 0 otherwise.
If w0 is the longest element of W, the element of greatest length or equivalently the element sending Φ+ to −Φ+, then
More generally
for some constants as,t.
Set
and
Then Ps is a homogeneous polynomial of degree .
These polynomials are the Kostant polynomials.
Properties
Theorem. The Kostant polynomials form a free basis of the ring of polynomials over the W-invariant polynomials.
In fact the matrix
is unitriangular for any total order such that s ≥ t implies .
Hence
Thus if
with as invariant under W, then
Thus
where
another unitriangular matrix with polynomial entries.
It can be checked directly that as is invariant under W.
In fact δi satisfies the derivation property
Hence
Since
or 0, it follows that
so that by the invertibility of N
for all i, i.e. at is invariant under W.
Steinberg basis
As above let Φ be a root system in a real inner product space V, and Φ+ a subset of positive roots. From these data we obtain the subset Δ = {α1, α2, …, αn} of the simple roots, the coroots
and the fundamental weights λ1, λ2, ..., λn as the dual basis of the coroots.
For each element s in W, let Δs be the subset of Δ consisting of the simple roots satisfying s−1α < 0, and put
where the sum is calculated in the weight lattice P.
The set of linear combinations of the exponentials eμ with integer coefficients for μ in P becomes a ring over Z isomorphic to the group algebra of P, or equivalently to the representation ring
R(T) of T, where T is a maximal torus in K, the simply connected, connected compact semisimple Lie group with root system Φ. If W is the Weyl group of Φ, then the representation ring R(K) of K can be identified with R(T)W.
Steinberg's theorem. The exponentials λs (s in W) form a free basis for the ring of exponentials over the subring of W-invariant exponentials.
Let ρ denote the half sum of the positive roots, and A denote the antisymmetrisation operator
The positive roots β with sβ positive can be seen as a set of positive roots for a root system on a subspace of V; the roots are the ones orthogonal to s.λs. The corresponding Weyl group equals the stabilizer of λs in W. It is generated by the simple reflections sj for which sαj is a positive root.
Let M and N be the matrices
where ψs is given by the weight s−1ρ - λs. Then the matrix
is triangular with respect to any total order on W such that s ≥ t implies .
Steinberg proved that the entries of B are W-invariant exponential sums. Moreover its diagonal entries all equal 1, so it has determinant 1. Hence its inverse C has the same form. Define
If χ is an arbitrary exponential sum, then it follows that
with as the W-invariant exponential sum
Indeed this is the unique solution of the system of equations
References
Invariant theory
Topology of homogeneous spaces
Algebraic groups | Kostant polynomial | Physics | 1,230 |
12,533 | https://en.wikipedia.org/wiki/Geocaching | Geocaching (, ) is an outdoor recreational activity, in which participants use a Global Positioning System (GPS) receiver or mobile device and other navigational techniques to hide and seek containers, called geocaches or caches, at specific locations marked by coordinates all over the world. The first geocache was placed in 2000, and by 2023 there were over 3 million active caches worldwide.
Geocaching can be considered a real-world, outdoor treasure hunting game. A typical cache is a small waterproof container containing a logbook and sometimes a pen or pencil. The geocacher signs the log with their established code name/username and dates it, in order to prove that they found the cache. After signing the log, the cache must be placed back exactly where the person found it. Larger containers such as plastic storage containers (Tupperware or similar) or ammo boxes can also contain items for trading, such as toys or trinkets, usually of more sentimental worth than financial. Geocaching shares many aspects with benchmarking, trigpointing, orienteering, treasure hunting, letterboxing, trail blazing, and another type of location-based game called Munzee.
History
Geocaching is similar to the game letterboxing (originating in 1854), which uses clues and references to landmarks embedded in stories. Geocaching was conceived shortly after the removal of Selective Availability from the Global Positioning System on May 2, 2000 (Blue Switch Day), because the improved accuracy of the system allowed for a small container to be specifically placed and located.
The first documented placement of a GPS-located cache took place on May 3, 2000, by Dave Ulmer in Beavercreek, Oregon. The location was posted on the Usenet newsgroup sci.geo.satellite-nav at . Within three days, the cache had been found twice, first by Mike Teague. According to Dave Ulmer's message, this cache was a black plastic bucket that was partially buried and contained various items, such as software, videos, books, money, a can of beans, and a slingshot. The geocache and most of its contents were eventually destroyed by a lawn mower, but the can of beans was the only item salvaged and was later turned into a trackable item known as the "Original Can of Beans". Another geocache and plaque, called the Original Stash Tribute Plaque, now sits at the site.
Geocaching company Groundspeak allows extraterrestrial caches, e.g. the Moon or Mars, although presently, the website provides only earthbound coordinates. The first published extraterrestrial geocache was GC1BE91, which was placed on the International Space Station by Richard Garriott in 2008. It used the Baikonur launch area in Kazakhstan as its position. The original cache contained a Travel Bug (the first geocaching trackable item in space), which stayed on the station until it was brought back to earth in 2013. Due to fire restrictions on board the station, the geocache contained no official paper logbook. As of June 2024, only one confirmed geocacher (on November 17, 2013) has actually found the geocache, although others have claimed to have found it providing varying amounts of evidence. To commemorate the occasion, Groundspeak allowed specialized geocaching events to be published across the world, allowing attendees to obtain a virtual souvenir on their profile.
The second geocaching trackable in space is TB5EFXK which is attached to the SHERLOC calibration target on board the Mars Perseverance Rover, which landed on Mars on 18 February 2021. Geocachers were given the opportunity to virtually discover the trackable after the WATSON camera sent back its first photographs of the calibration target that contained the tracking code number. The code is printed on a prototype helmet visor material that will be used to test how well it can withstand the Martian environment. This will help scientists in creating a viable Martian spacesuit for future crewed missions to Mars.
The activity was originally referred to as the GPS stash hunt or gpsstashing. This was changed shortly after the original hide when it was suggested in the gpsstash eGroup that "stash" could have negative connotations and the term geocaching was adopted.
Over time, a variety of different hide-and-seek-type activities have been created or abandoned, so that "Geocaching" may now refer to hiding and seeking containers, or locations or information without containers.
An independent accounting of the early history documents several controversial actions taken by Jeremy Irish and Grounded, Inc., a predecessor to Groundspeak, to increase "commercialization and monopolistic control over the hobby". More recently, other similar hobbies such as Munzee have attracted some geocachers by rapidly adopting smart-phone technology, which has caused "some resistance from geocaching organizers about placing caches along with Munzees".
Geocaches
For the traditional geocache, a geocacher will place a waterproof container containing a log book, often also a pen and/or pencil and trade items or trackables, then record the cache's coordinates. These coordinates, along with other details of the location, are posted on a listing site (see list of some sites below). Other geocachers obtain the coordinates from that listing site and seek out the cache using their handheld GPS receivers. The finding geocachers record their exploits in the logbook and online, but then must return the cache to the same coordinates so that other geocachers may find it. Geocachers are free to take objects (except the logbook, pencil, or stamp) from the cache in exchange for leaving something of similar or higher value.
Typical cache "treasures", also known in the geocaching world as SWAG (a backronym of "stuff we all get"), are not high in monetary value but may hold personal value to the finder. Aside from the logbook, common cache contents are unusual coins or currency, small toys, ornamental buttons, CDs, or books. Although not required, many geocachers decide to leave behind signature items, such as personal geocoins, pins, or craft items, to mark their presence at the cache location. Disposable cameras are popular as they allow for anyone who found the cache to take a picture which can be developed and uploaded to a geocaching web site listed below. Also common are objects that are moved from cache to cache called "hitchhikers", such as Travel Bugs or geocoins, whose travels may be logged and followed online. Cachers who initially place a Travel Bug or Geocoin(s) often assign specific goals for their trackable items. Examples of goals are to be placed in a certain cache a long distance from home, or to travel to a certain country, or to travel faster and farther than other hitchhikers in a race. Less common trends are site-specific information pages about the historic significance of the site, types of trees, birds in the area or other such information. Higher-value items are occasionally included in geocaches as a reward for the First to Find (called "FTF"), or in locations which are harder to reach.
Dangerous or illegal items, including weapons and drugs, are not allowed and are specifically against the rules of most geocache listing sites. Food is also disallowed, even if sealed, as it is considered unhygienic and can attract animals.
If a geocache has been vandalized or stolen by a person who is not familiar with geocaching, it is said to have been "muggled". The term plays off the fact that those not familiar with geocaching are called "muggles", a word borrowed from the Harry Potter series of books which were rising in popularity at the same time geocaching started.
Variations
Geocaches vary in size, difficulty, and location. Simple caches that are placed near a roadside are often called "drive-bys", "park 'n grabs" (PNGs), or "cache and dash". Geocaches may also be complex, involving lengthy searches, significant travel, or use of specialist equipment such as SCUBA diving, kayaking, or abseiling. Different geocaching websites list different variations per their own policies.
Container sizes range from nano, particularly magnetic nanos, which can be smaller than the tip of a finger and have only enough room to store the log sheet, to 20-liter (5 gallon) buckets or even larger containers, such as entire trucks. The most common cache containers in rural areas are lunch-box-sized plastic storage containers or surplus military ammunition cans. Ammo cans are considered the gold standard of containers because they are very sturdy, waterproof, animal- and fire-resistant, and relatively cheap, and have plenty of room for trade items. Smaller containers are more common in urban areas because they can be more easily hidden.
Geocache types
Over time many variations of geocaches have developed. Different platforms often have their own rules on which types are allowed or how they are classified. The following cache types are supported by geocaching.com.
Traditional cache
The simplest form of a geocache. It consists of a container with a log sheet, and is located at the posted coordinates. Cache containers come in many different sizes.
Night cache
These caches are intended to be found at night, usually by use of a UV torch.
Multi-cache
These caches include at least one stage in addition to the physical final container with a log sheet. The posted coordinates for a multi-cache are the first stage. At each stage, the geocacher gathers information that leads them to the next stage or to the final container. Multi-caches can consist of physical stages (i.e. the first stage contains coordinates for the next stage and so forth) or virtual stages (i.e. the first stage is a historical marker where geocachers have to answer questions to calculate the coordinates to the final physical container).
Mystery cache
Also called a 'puzzle cache', players might need to solve a puzzle or bring a special tool to reveal the next waypoint or final coordinates. Most often, the final container is not at the posted coordinates which is noted in the cache description. Some puzzles can be easy and involve basic math operations or they can be quite difficult, with some of the more challenging ones requiring a firm understanding of computer programming. Geocaching Toolbox, a website dedicated to create and solve puzzle geocaches, provides a comprehensive list of common puzzle cache ciphers.
There are also some subcategories of the mystery cache, which are normally listed as a Mystery Type, which are listed below.
Challenge cache
This requires a geocacher to complete a reasonably attainable geocaching-related task before being able to log the cache as a find online. It does not restrict geocachers from finding the cache and signing the logbook at anytime. However a geocacher is not allowed to log a find on the geocaching website unless they qualify for the challenge specified in the cache description. Examples include finding a number of caches that meet a category, completing a number of cache finds within a period of time, or finding a cache for every calendar day.
Since 2017, Groundspeak has required new challenges to have a geochecker in which users can put their name into an algorithm to see if they qualify without the need of physically checking all of one's previous finds. These geocheckers can be requested using the ProjectGC forums where volunteers can write and create scripts for specific challenges. Groundspeak also has been more strict into what types of challenges are published. For example, prior to 2017 it was possible to create a challenge cache to find 10 caches that have a food item in the title. Under current guidelines, this is no longer allowed because it restricts geocachers to find specific geocaches. Instead, Groundspeak has encouraged new challenges to be more creative. Acceptable challenges include finding caches in 10 states, finding 100 traditional geocaches, or finding 1000 geocaches with the "wheelchair accessible" attribute.
Bonus cache
A bonus cache requires the finder to have found an amount of caches, usually by the same hider, before finding the bonus cache. The cache can be any type, however a bonus cache cannot be required for a second bonus cache.
Moving or travelling cache
These were found at a listed set of coordinates. The finder hides the cache in a different location, and updates the listing, essentially becoming the hider, and the next finder continues the cycle. This cache has been discontinued at geocaching.com and those that have been grandfathered in are solely declining and are being archived.
Chirp cache
Also known as a wireless beacon cache. This is a Garmin-created innovative on multi-caches using wireless beacon technology. It is a physical game piece, about the size of a half dollar that can be hidden anywhere. Powered by a small battery, it is able to transmit a signal detectable on Garmin devices. The Chirp stores hints, multicache coordinates, counts visitors, and can confirm the cache is nearby. These caches caused considerable discussion and some controversy at Groundspeak, where they were ultimately given a new "attribute". These types of geocaches can also be listed as a traditional, multi-cache, or letterbox. It is up to the cache owner to designated the cache type for wireless beacon caches.
Geocaching HQ geocache (GCK25B)
This is an official geocache located inside the Groundspeak headquarters office in Seattle, Washington. It is technically classified as a separate cache type under mystery caches, with its own unique icon both on the geocaching app and on one's profile statistics tab. Since publication in 2004, it has over 20,000 finds as of June 2024.
Wherigo cache
A multi-stage cache hunt that uses a Wherigo "cartridge" to guide players to find a physical cache sometime during cartridge play, usually at the end. However, not all Wherigo cartridges incorporate geocaches into gameplay. Wherigo caches are unique to the geocaching.com website. Wherigo is a GPS location-aware software platform initially released in January 2008. Authors can develop self-enclosed story files (called "cartridges") that are read by the Wherigo player software, installed on either a GPS unit or smartphone. The player and story take advantage of the location information provided by the GPS to trigger in-game events, such as using a virtual object or interacting with characters. Completing an adventure can require reaching different locations and solving puzzles. Cartridges are coded in Lua. Lua may be used directly, but a builder application is usually used. The Wherigo site offers a builder application and a database of adventures free for download, though the builder has remained in its Alpha version since its last release in May 2008. The official player is only available for Pocket PC. A built-in player is available on Garmin Colorado and Oregon GPS models. The Wherigo Foundation was organized in December 2012. The group is composed of all Wherigo application developers who, up until that time, had been acting and developing separately. Their goal is to provide a consistent Wherigo experience across platforms, connect Wherigo applications via an API, and add modern features to the Wherigo platform. While Groundspeak is aware of this project, the company has yet to take a position.
Reverse Wherigo
An RWIG provides three lines of code composed of 9 digits each that a player can type into the RWIG cartridge. Instead of following a story or interacting with characters, and RWIG gives you the distance to the final cache, but not direction. It requires geocachers to get closer to the final geocache by process of elimination. Once you are within 25 metres, the final coordinates are given to provide a more accurate location for the geocache.
Letterbox hybrid
This is a combination of a geocache and a letterbox in the same container. Letterboxes involve a rubber stamp and logbook that are not supposed to be traded and taken instead of tradable items, but letterbox hybrids may or may not include trade items. Letterboxers carry their own stamp with them, to stamp the letterbox's logbook and inversely stamp their personal logbook with the letterbox stamp. The letterbox hybrid cache contains the important materials for this. Typically, letterbox hybrid caches are not found at the given coordinates which only act as a starting location. Instead, a series of clues are given as to where to find the cache such as "take a left past the bridge" or "about 25 paces past the big oak tree".
Project A.P.E. cache
Also known as Ape caches, these are a special type of traditional cache that were hidden in conjunction with 20th Century Fox and Groundspeak to promote the 2001 remake of Planet of the Apes. There were 14 APE geocaches placed around the world and each one contained a prop from the film. As of 2023, only 2 APE caches are still active with one near Seattle, Washington ('Tunnel of Light', GC1169) and the other in Brazil ('Southern Bowl', GCC67). Of those two, the Brazil APE cache is the only surviving original APE cache because GC1169 was muggled in 2016. However, the original container was later found by a Groundspeak led survey in April of that year. What remains of "Tunnel of Light" is an "official" replacement of the original ammo can that was left in 2001.
Virtual cache
This cache type does not contain a physical logbook. They are normally hidden at a rather interesting or unique location, usually with a described object such as an art sculpture or a scenic lookout. Validation for finding a virtual cache generally requires one to email the cache hider with information such as a date or a name on a plaque, or to post a picture of oneself at the site with a GPS receiver in hand. As of 2005, new virtual caches are no longer allowed by Groundspeak as it is considered a legacy cache.
On August 24, 2017, Groundspeak announced "Virtual Rewards", allowing 4000 new virtual caches to be placed during the following year. Each year, eligible geocachers can opt-in to a drawing and some selected with the opportunity to submit a virtual cache for publication. From 2005 to 2017, the geocaching website no longer listed new caches without a physical container, including virtual and webcam caches (with the exception of earthcaches and events); however, older caches of these types have been grandfathered.
EarthCache
Similar to virtual geocaches, an Earth cache is published not by a local reviewer, but by a volunteer regional reviewer associated with the Geological Society of America. The geocacher usually has to perform a task which teaches an education lesson about the geology of the cache area. Visitors must answer geological questions to complete the cache which can be as simple as describing the color and thickness of layers in an outcrop or can be as complicated as taking measurements of stream velocities or fault offsets. Earthcaches covers geologic topics such as: rock formation, mineralogy, earthquakes, fluvial processes, erosion, volcanology, and planetary science (among others).
Locationless cache
Otherwise known as a Reverse cache, a locationless cache is similar to a scavenger hunt. A description is given for something to find, such as a one-room schoolhouse, and the finder locates an example of this object. The finder records the location using their GPS receiver and often takes a picture at the location showing the named object with their GPS receiver. Typically others are not allowed to log that same location as a find.
Since 2005, all locationless caches have been archived and locked, meaning they are unable to be logged. However, with geocaching's 20th anniversary in 2020 Groundspeak decided to publish a special locationless cache for geocachers to "find" at various Mega- and Giga-Events around the world. The first locationless cache in 15 years (GC8FR0G) required finders to take a picture of themselves with the geocaching mascot, Signal the Frog, at Mega- and Giga-Events during 2020. The cache was made available to log starting 1 January 2020. However, because of the COVID-19 pandemic, nearly all planned Mega- and Giga-events were cancelled for the year, including the planned 20th anniversary celebration event in Seattle, Washington. Therefore, Groundspeak decided to extend the deadline to log this geocache through 1 January 2023. With 22,500 finds it is the second most logged geocache in history.
The second published locationless cache since 2005 (GC8NEAT) required visitors to take a photo of them picking up trash and cleaning up their local area. geocachers were able to log this cache from 6 February 2021 through 31 December 2022. It has been logged over 33,500 times and holds the title for the most "found" geocache. On 17 August 2022, Geocaching.com made available the third locationless cache to be logged since 2005 (GC9FAVE). Instead of finding Signal or picking up trash, this cache encouraged geocachers from around the world to share their favorite geocaching story. This geocache was archived and locked on 1 January 2024.
Webcam cache
A type of virtual cache whose coordinates provide the location to a public webcam. The finder is required to capture an image of themselves through the webcam for verification of the find. New webcam caches are no longer allowed by Groundspeak as it is a legacy cache. Webcam caches are a category at Waymarking.com.
Adventure Lab
A type of virtual cache that typically consists of a set of 5 waypoints, with each waypoint counting as a "cache find". The waypoints usually have an overall theme such showcasing the history of a small town and are often created as a walking tour of a city or park. An example would be Route 66 or the Lincoln Highway, which are a nationwide series of Adventure Lab sets of 10 that stretch the entire route across the United States.
Adventure labs were first introduced in 2014 as a way to test market ideas through Groundspeak. Initially, geocachers would find a key word at a designated site where they could then enter it onto a website to claim "credit". Soon after, they were made available to "find" at select Mega-Events. In 2020, Groundspeak released the "Adventure Lab" app, separate from the geocaching app. The app made it possible to enter a geo-fence when, once inside, a question will appear that can be answered either in the form of a written answer or a multiple choice answer. This question can be answered at anytime once activated, however, some Adventure Labs must be completed sequentially implying that one must answer the question to move on to the next waypoint.
Many Adventure Labs caches have a physical bonus cache associated with them that are listed as a "mystery cache". Coordinates to the bonus cache, if applicable, can be seen in the journal entries once a user has correctly answered the question at a waypoint.
Geocachers can create their own Adventure Lab, but must first opt-in to receive an "Adventure Lab credit" which allows for the creation of 1 set of 5 waypoints, with each of the 5 waypoints counting towards a cache find. If selected, Adventure Labs can be created using the Adventure Lab builder. Adventure Labs, unlike all other geocaches, are not subject to review and are published at will by the creator. However, Adventure Labs can at anytime be archived by Groundspeak if they are in violation of terms of use. For example, placing an Adventure Lab in a place that requires people to pay a fee to visit such as airports or theme parks may get the Adventure permanently removed from the Adventure Lab app.
Event caches
There are several kinds of events geocaches. While encouraged, events do not require visitors to sign their name a logbook to prove they attended an event. Attendees of event caches can log that they 'attended', which will increment their number of found caches. Event caches can be of the following types:
Event: An event cache is a gathering of local geocachers or geocaching organizations. The event cache page specifies a time for the event and provides coordinates to its location. Event caches have to be longer than 30 minutes, and can publish no less than 14 days away from the planned event date. Event caches typically last from 1 to 2 hours.
Cache-In Trash-Out Event (CITO): is an environmental initiative to clean up and preserve the natural areas that geocachers frequent. These events are gatherings of the geocaching community that can focus on services like litter clean-up, removal of invasive species, planting trees and vegetation, and trail building. CITO events must be no less than 2 hours long. Just like event caches, CITOs have to be published no less than 14 days prior to the date of the CITO. CITO typically last from 2 to 4 hours.
Mega-Event: Just like an event cache, however it has to consist of 500 or more geocachers. Mega events are typically organized by a local geocache organizations in conjunction with local municipalities and promotion from Groundspeak. Often, mega events last an entire day and have various activities planned in the days before, during, and after the main Mega-Event. These activities can range in raffles and silent auctions, of which funds help offset the costs of organizing such an event, photo ops with Signal the Frog, a plethora of new geocaches, and panels with local geocachers, lackeys (Groundspeak employees), and reviewers. Mega-Events often have vendors where people can purchase geocoins, cache containers, and food.
Giga-Event: Just like an event cache, however it has to consist of 5,000 or more geocachers. Like a Mega-Event, Giga-Events offer a plethora of actives and are typically held in large areas to accommodate such crowds. Activities typically include a GPS Adventures Maze, panels, vendors, live music, and carnival rides. Usually the week before and after are filled with smaller gatherings which attracts geocachers from around the world who often make a vacation out of it. Only one can happen at a time in the world.
GPS Adventures Maze Exhibit: The GPS Adventures Maze is a traveling exhibit designed to teach people of all ages about GPS technology and geocaching through interactive science experiences. It may accompany a Mega- or Giga-Event. These "events" have their own cache type on geocaching.com and often include many non-geocachers.
Community Celebration Event (CCE): A type of event that is meant to celebrate the 10th and 20th anniversary of geocaching. First issued in 2010 as "Lost and Found" events, geocachers could host one to celebrate the 10 year anniversary of geocaching. In preparation for the 20th anniversary in 2020, Lost and Found events were rebranded as Community Celebration Events. Geocachers could opt-in to receive a CCE credit to host. Due to the Covid-19 Pandemic, Groundspeak allowed CCEs to be hosted until 31 December 2022. Geocaching HQ will be allowing geocachers to host CCEs in 2025, assuming they meet specific criteria.
Geocaching HQ Block Party: Hosted at Geocaching HQ, a Geocaching HQ Block party is hosted at significant milestones for Geocaching's years of existence.
Technology
Obtaining data
GPX files containing information such as a cache description and information about recent visitors to the cache are available from various listing sites. Geocachers may upload geocache data (also known as waypoints) from various websites in various formats, most commonly in file-type GPX, which uses XML. Some websites allow geocachers to search (build queries) for multiple caches within a geographic area based on criteria such as ZIP code or coordinates, downloading the results as an email attachment on a schedule. In recent years, Android and iPhone users can download apps such as GeoBeagle that allow them to use their 3G and GPS-enabled devices to actively search for and download new caches.
Converting and filtering data
A variety of geocaching applications are available for geocache data management, file-type translation, and personalization. Geocaching software can assign special icons or search (filter) for caches based on certain criteria (e.g. distance from an assigned point, difficulty, date last found).
Paperless geocaching means hunting a geocache without a physical printout of the cache description. Traditionally, this means that the seeker has an electronic means of viewing the cache information in the field, such as pre-downloading the information to a PDA or other electronic device. Various applications can directly upload and read GPX files without further conversion. Newer GPS devices released by Garmin, DeLorme, and Magellan have the ability to read GPX files directly, thus eliminating the need for a PDA. Other methods include viewing real-time information on a portable computer with internet access or with an Internet-enabled smart phone. The latest advancement of this practice involves installing dedicated applications on a smart phone with a built-in GPS receiver. Seekers can search for and download caches in their immediate vicinity directly to the application and use the on-board GPS receiver to find the cache.
A more controversial version of paperless Caching involves mass-downloading only the coordinates and cache names (or waypoint IDs) for hundreds of caches into older receivers. This is a common practice of some cachers and has been used successfully for years. In many cases, however, the cache description and hint are never read by the seeker before hunting the cache. This means they are unaware of potential restrictions such as limited hunt times, park open/close times, off-limit areas, and suggested parking locations.
Mobile devices
The website geocaching.com now sells mobile applications which allow users to view caches through a variety of different devices. Currently, the Android, iOS, and Windows Phone mobile platforms have applications in their respective stores. The apps also allow for a trial version with limited functionality. The site promotes mobile applications, and lists over two dozen applications (both mobile and browser/desktop based) that are using their proprietary but royalty-free public application programming interface (API). Developers at c:geo have criticised Groundspeak for being incompatible with open-source development.
Additionally, "c:geo - opensource" is a free opensource full function application for Android phones that is very popular. This app includes similar features to the official Geocaching mobile application, such as: View caches on a live map (Google Maps or OpenStreetMap), navigation using a compass, map, or other applications, logging finds online and offline, etc.
Geocaching enthusiasts have also made their own hand-held GPS devices using a Lego Mindstorms NXT GPS sensor.
Ethics
Geocache listing websites have their own guidelines for acceptable geocache publications. Government agencies and others responsible for public use of land often publish guidelines for geocaching, and a "Geocacher's Creed" posted on the Internet asks participants to "avoid causing disruptions or public alarm". Generally accepted rules are to not endanger others, to minimize the impact on nature, to respect private property, and to avoid public alarm.
Reception
The reception from authorities and the general public outside geocache participants has been mixed.
Cachers have been approached by police and questioned when they were seen as acting suspiciously. Other times, investigation of a cache location after suspicious activity was reported has resulted in police and bomb squad discovery of the geocache, such as the evacuation of a busy street in Wetherby, Yorkshire, England in 2011, and a street in Alvaston, Derby in 2020.
Schools have been evacuated when a cache has been seen by teachers or police, such as the case of Fairview High School in Boulder, Colorado in 2009. A number of caches have been destroyed by bomb squads. Diverse locations, from rural cemeteries to Disneyland, have been locked down as a result of such scares.
The placement of geocaches has occasional critics among some government personnel and the public at large, who consider it Littering. Some geocachers act to mitigate this perception by picking up litter while they search for geocaches, a practice referred to in the community as "Cache In Trash Out". Events and caches are often organized revolving around this practice, with many areas seeing significant cleanup that would otherwise not take place, or would instead require federal, state, or local funds to accomplish. Geocachers are also encouraged to clean up after themselves by retrieving old containers once a cache has been removed from play.
Geocaching is legal in most countries and is usually positively received when explained to law enforcement officials. However, certain types of placements can be problematic. Although generally disallowed, hiders could place caches on private property without adequate permission (intentionally or otherwise), which encourages cache finders to trespass. Historic buildings and structures have also been damaged by geocachers, who have wrongly believed the geocache can be/has been placed within, or on the roof of, the buildings.
Caches might also be hidden in places where the act of searching can make a finder look suspicious (e.g., near schools, children's playgrounds, banks, courthouses, or in residential neighborhoods), or where the container placement could be mistaken for a drug stash or a bomb (especially in urban settings, under bridges, near banks, courthouses, or embassies). As a result, geocachers are strongly advised to label their geocaches when possible, so that they are not mistaken for a harmful object if discovered by non-geocachers.
As well as concerns about littering and bomb threats, some geocachers have hidden their caches in inappropriate locations, such as electrical boxes, which may encourage risky behavior, especially by children. Hides in these areas are discouraged, and cache listing websites enforce guidelines that disallow certain types of placements. However, as cache reviewers typically cannot see exactly where and how every cache is hidden, problematic hides can slip through. Ultimately it is also up to cache finders to use discretion when attempting to search for a cache, and report any problems.
Laws and legislation
Regional rules for placement of caches have become complex. For example, in Virginia, the Virginia Department of Transportation and the Wildlife Management Agency now forbids the placement of geocaches on all land controlled by those agencies. Some cities, towns, and recreation areas allow geocaches with few or no restrictions, but others require compliance with lengthy permitting procedures.
The South Carolina House of Representatives passed Bill 3777 in 2005, stating, "It is unlawful for a person to engage in the activity of Geocaching or letterboxing in a cemetery or in a historic or archaeological site or property publicly identified by a historical marker without the express written consent of the owner or entity which oversees that cemetery site or property." The bill was referred to committee on first reading in the Senate and has been there ever since.
The Illinois Department of Natural Resources requires geocachers who wish to place a geocache at any Illinois state park to submit the location on a USGS 7.5 minute topographical map, the name and contact information of the person(s) wishing to place the geocache, a list of the original items to be included in the geocache, and a picture of the container that is to be placed.
In April 2020, during the COVID-19 pandemic, the township of Highlands East, Ontario, Canada temporarily banned geocaching, over concerns that geocache containers could not be properly disinfected between finds.
Notable incidents
Several deaths have occurred during the course of Caching.
The death of a 21-year-old experienced cacher in December 2011 "while attempting a Groundspeak Cache that does not look all that dangerous" led to discussions of whether changes should be made, and whether cache owners or Groundspeak could be held liable. Groundspeak has since updated their geocaching.com terms of use agreement to specify that geocachers find geocaches at their own risk.
In 2008, two lost hikers on Mount Hood in Oregon, U.S. stumbled across a geocache and phoned this information out to rescuers, allowing crews to locate and rescue them.
Three adult geocachers, a 24-year-old woman and her parents, were trapped in a cave and rescued by firefighters in Rochester, New York, U.S. while searching for a geocache in 2012. Rochester Fire Department spokesman Lt. Ted Kuppinger said, "It's difficult, because you're invested in it, you want to find something like that, so people will probably try to push themselves more than they should, but you need to be prudent about what you're capable of doing."
In 2015, members of the public called the British coastguard to check on a group of geocachers who were spotted walking into the Severn Estuary off the coast of Clevedon, England, in search of clues to locate a multi-cache. Although they felt they were safe and able to return to land, they were considered to be in danger and were airlifted back to the shore.
In October 2016, four people discovered a crashed car at the bottom of a ravine in Benton County, Washington, U.S., while out geocaching. They spotted the driver still trapped inside and alerted emergency services, who rescued the driver.
On 9 June 2018, four people in Prague, Czech Republic were searching for a cache in a 4 km long tunnel when a storm surge carried them through the tunnel to its terminus at the Vltava river. Two of the geocachers died, while two others were rescued from the river.
Websites and data ownership
Numerous websites list geocaches around the world. .Geocaching websites vary in many ways, such as subscription options, activity levels, and volunteers available to check and ensure caches registered remain open for others.
First page
The first website to list geocaches was announced by Mike Teague on May 8, 2000. On September 2, 2000, Jeremy Irish emailed the gpsstash mailing list that he had registered the domain name geocaching.com and had set up his own Web site. He copied the caches from Mike Teague's database into his own. On September 6, Mike Teague announced that Jeremy Irish was taking over cache listings. , Teague had logged only 5 caches.
Geocaching.com
The largest site is Geocaching.com, owned by Groundspeak Inc., which began operating in late 2000. With a worldwide membership and a freemium business model, the website claims millions of caches and members in over 190 countries and all seven continents including Antarctica. Hides and events are reviewed by volunteer regional cache reviewers before publication. Free membership allows users access to coordinates, descriptions, and logs for some caches; for a subscription fee, users are allowed additional search tools, the ability to download large amounts of cache information onto their GPS at once, instant email notifications about new caches, and access to premium-member-only caches (although, you can still access such caches on the website itself; the premium cache restriction only applies to the application). Geocaching Headquarters are located in the Fremont neighborhood of Seattle, Washington, United States.
Opencaching Network
The Opencaching Network provides independent, non-commercial listing sites based in the cacher's country or region. The Opencaching Network lists the most types of caches, including traditional, virtual, moving, multi, quiz, webcam, BIT, guest book, USB, event, and MP3. The Opencaching Network is less restrictive than many sites, and does not charge for the use of the sites, the service being community-driven. Some (or all) listings may or may not be required to be reviewed by community volunteers before being published and although cross-listing is permitted, it is discouraged. Some listings are listed on other sites, but there are many that are unique to the Opencaching Network. Features include the ability to organize one's favourite caches, build custom searches, be instantly notified of new caches in one's area, seek and create caches of all types, export GPX queries, statpics, etc. Each Opencaching Node provides the same API for free (called "OKAPI") for use by developers who want to create third-party applications which can use the Opencaching Network's content.
Countries with associated opencaching websites include the United States at www.opencaching.us; Germany at www.opencaching.de; Sweden at www.opencaching.se; Poland at www.opencaching.pl; Czech Republic at www.opencaching.cz; The Netherlands at www.opencaching.nl; Romania at www.opencaching.ro; the United Kingdom at www.opencache.uk.
The main difference between opencaching and traditional listing sites is that all services are open to the users at no cost. Generally, most geocaching services or websites offer some basic information for free, but users may have to pay for premium membership that allows access to more information or advanced searching capabilities. This is not the case with opencaching; every geocache is listed and accessible to everyone for free.
Additionally, Opencaching sites allow users to rate and report on existing geocaches. This allows users to see what other cachers think of the cache and it encourages participants to place higher-quality caches. The rating system also greatly reduces the problem of abandoned or unsatisfactory caches still being listed after repeated negative comments or posts in the cache logs.
OpenCaching.com
OpenCaching.com (short: OX) was a site created and run by Garmin from 2010 to 2015, which had the stated aim of being as free and open as possible with no paid content. Caches were approved by a community process and coordinates were available without an account. The service closed on 14 August 2015.
Other sites
In many countries there are regional geocaching sites, but these mostly only compile lists of caches in the area from the three main sites. Many of them also accept unique listings of caches for their site; these listings tend to be less popular than the international sites, although occasionally the regional sites may have more caches than the international sites. There are some exceptions, such as how, in the territory of the former Soviet Union, the site Geocaching.su remains popular because it accepts listings in the Cyrillic script. Additional international sites include Geocaching.de, a German website, and Geocaching Australia, which accepts listings of cache types deprecated by geocaching.com, cache types such as TrigPoint and Moveable caches, as well as traditional geocache types.
GPSgames
GPSgames.org was an online community dedicated to all kinds of games involving Global Positioning System receivers. GPSgames.org allowed traditional geocaches along with virtual, locationless, and traveler geocaches.
The site's geodashing game generated a large number of randomly positioned "dashpoints", requiring players to reach as many as possible, competing as individuals or teams.
Shutterspot, GeoVexilla, MinuteWar, GeoPoker, and GeoGolf were among the other GPS games available.
GPSgames.org was 100% free since 2001, through donations. The site was retired on 30 June 2021.
NaviCache
Navicache.com started as a regional listing service in 2001. While many of the website's listings have been posted to other sites, it also offers unique listings. The website lists nearly any type of geocache and does not charge to access any of the caches listed in its database. All submissions are reviewed and approved. In 2012 it was announced that Navicache was under transition to new owners, who said they "plan to develop a site that geocachers want, with rules that geocachers think are suitable. Geocaching.com and OX are both backed by large enterprises, and while that means they have more funding and people, we're a much smaller team – so our advantage is the ability to be dynamic and listen to the users." However, as of 2021 the site is mostly dormant, and the most recent cache listing is from 2014.
TerraCaching
Terracaching.com aims to provide high-quality caches made so by the difficulty of the hide or from the quality of the location. Membership is managed through a sponsorship system, and each cache is under continual peer review from other members. Terracaching.com embraces virtual caches alongside traditional or multi-stage caches and includes many locationless caches among the thousands of caches in its database. It is increasingly attracting members who like the point system. In Europe, TerraCaching is supported by Terracaching.eu. This site is translated in different European languages, has an extended FAQ and extra supporting tools for TerraCaching. TerraCaching strongly discourages caches that are listed on other sites (so-called double-listing).
Extremcaching
Extremcaching is a German private database for alternative geocaches with a focus on T5 / climbing caches, night caches, and lost place caches.
Geocaching Australia
Geocaching Australia is a community website for geocachers in Australia and New Zealand. Geocaching Australia also has many unique cache types such as Burke And Wills, Moveable_cache & Podcache geocaches.
See also
Augmented reality
Benchmarking
BookCrossing
Dead drop
Degree Confluence Project
Encounter
Geohashing
Geolocation-based video game
Ingress (video game)
Letterboxing (hobby)
Location-based game
Munzee
Orienteering
Pokémon Go
Puzzle hunt
Questing
Transmitter hunting
Treasure hunting
Treasure map
Highpointing
Peakbagging
References
Further reading
External links
In Wisconsin: Geocaching Video produced by Wisconsin Public Television
FTF Geocacher Magazine Print Magazine devoted to geocaching
geocaching.com The official geocaching website
Geosocial networking
Global Positioning System
Hobbies
Internet object tracking
Outdoor locating games
Scoutcraft
2000 neologisms
2000 establishments in Oregon
Sports originating in the United States
Games and sports introduced in 2000
Tourist attractions in Clackamas County, Oregon | Geocaching | Technology,Engineering | 9,738 |
1,519,744 | https://en.wikipedia.org/wiki/Fade%20%28audio%20engineering%29 | In audio engineering, a fade is a gradual increase or decrease in the level of an audio signal. The term can also be used for film cinematography or theatre lighting in much the same way (see fade (filmmaking) and fade (lighting)).
In sound recording and reproduction a song may be gradually reduced to silence at its end (fade-out), or may gradually increase from silence at the beginning (fade-in). Fading-out can serve as a recording solution for pieces of music that contain no obvious ending. Quick fade-ins and -outs can also be used to change the characteristics of a sound, such as to soften the attack in vocal plosives and percussion sounds.
Professional turntablists and DJs in hip hop music use faders on a DJ mixer, notably the horizontal crossfader, in a rapid fashion while simultaneously manipulating two or more record players (or other sound sources) to create scratching and develop beats. Club DJs in house music and techno use DJ mixers, two or more sound sources (two record players, two iPods, etc.) along with a skill called beatmatching (aligning the beats and tempos of two records) to make seamless dance mixes for dancers at raves, nightclubs and dance parties.
History
Origins and examples
Possibly the earliest example of a fade-out ending can be heard in Joseph Haydn's Symphony No. 45, nicknamed the "Farewell" Symphony on account of the fade-out ending. The symphony which was written in 1772 used this device as a way of courteously asking Haydn's patron Prince Nikolaus Esterházy, to whom the symphony was dedicated, to allow the musicians to return home after a longer than expected stay. This was expressed by the players extinguishing their stand candles and leaving the stage one by one during the final adagio movement of the symphony, leaving only two muted violins playing. Esterházy appears to have understood the message, allowing the musicians to leave.
Gustav Holst's "Neptune, the mystic", part of the orchestral suite The Planets written between 1914 and 1916, is another early example of music having a fade-out ending during performance. Holst stipulates that the women's choruses are "to be placed in an adjoining room, the door of which is to be left open until the last bar of the piece, when it is to be slowly and silently closed", and that the final bar (scored for choruses alone) is "to be repeated until the sound is lost in the distance". Although commonplace today, the effect bewitched audiences in the era before widespread recorded sound—after the initial 1918 run-through, Holst's daughter Imogen (in addition to watching the charwomen dancing in the aisles during "Jupiter") remarked that the ending was "unforgettable, with its hidden chorus of women's voices growing fainter and fainter ... until the imagination knew no difference between sound and silence".
The technique of ending a spoken or musical recording by fading out the sound goes back to the earliest days of recording. In the era of mechanical (pre-electrical) recording, this could only be achieved by either moving the sound source away from the recording horn, or by gradually reducing the volume at which the performer(s) were singing, playing or speaking. With the advent of electrical recording, smooth and controllable fadeout effects could be easily achieved by simply reducing the input volume from the microphones using the fader on the mixing desk. The first experimental study on the effect of a fade-out showed that a version of a musical piece with fade-out in comparison to the same piece with a cold end prolonged the perceived duration by 2.4 seconds. This is called the "Pulse Continuity Phenomenon" and was measured by a tapping-along task to measure participants’ perception of pulsation.
An 1894 78 rpm record called "The Spirit of '76" features a narrated musical vignette with martial fife-and-drum that gets louder as it nears the listener, and quieter as it moves away. There are early examples that appear to bear no obvious relationship to movement. One is "Barkin' Dog" (1919) by the Ted Lewis Jazz Band. Another contender is "America" (1918), a patriotic piece by the chorus of evangelist Billy Sunday. By the early 1930s, longer songs were being put on both sides of records, with the piece fading out at the end of side one and fading back in at the beginning of side two. Records at the time held only about two to five minutes of music per side. The segue allowed for longer songs (such as Count Basie's "Miss Thing"), symphonies and live concert recordings.
However, shorter songs continued to use the fade-out for unclear reasons—for example, Fred Astaire's movie theme "Flying Down to Rio" (1933). Even using fade-out as a segue device does not seem obvious, though we certainly take it for granted today. It is possible that movies were an influence here. Fade-ins and fade-outs are often used as cinematic devices that begin and end scenes; film language that developed at the same time as these early recordings. The term fade-out itself is of cinematic origin, appearing in print around 1918. And jazz, a favorite of early records, was a popular subject of early movies too. The same could be said for radio productions. Within a single programme of a radio production, many different types of fade can be applied. When mixing from speech to music, there are a few ways that fade can be used. Here are three examples.
Straight: the introduction has become a musical link between the music/speech that follows, additionally the first notes of the intro can be emphasized to make it pop out more.
Cutting the introduction: Since the first word of the vocals has to follow promptly after the cue light, it could be used to move the recording onward.
Introduction under speech: The music is placed at the specified time on the cue, the level must be low in order for the vocals to be audible. Here the fade-up generally occurs just before the final words in order for the cue to be given. In stage productions the closing music is played from a predetermined time and fades up at the closing words in order to fit in exactly with the remaining program time.
Though relatively rare, songs can fade out then fade back in. Some examples of this are "Helter Skelter" and "Strawberry Fields Forever" by The Beatles, "Suspicious Minds" by Elvis Presley, "Shine On Brightly" by Procol Harum, "Sunday Bloody Sunday" by John Lennon and Yoko Ono, "That Joke Isn't Funny Anymore" by The Smiths, "Thank You" by Led Zeppelin, "In Every Dream Home A Heartache" by Roxy Music, "It's Only Money, Pt. 2" by Argent, "The Great Annihilator" by Swans, "(Reprise) Sandblasted Skin" by Pantera, "Illumination Theory" and "At Wit's End" by Dream Theater, "Future" by Paramore, "Doomsday" by MF Doom, "Outro" by M83, "Cold Desert" by Kings of Leon, and "The Edge Of The World" by DragonForce.
Contemporary
No modern recording can be reliably identified as "the first" to use the technique. In 2003, on the (now-defunct) website Stupid Question, John Ruch listed the following recordings as possible contenders:
More recently: "At the meta-song level, the prevalence of pre-taped sequences (for shops, pubs, parties, concert intervals, aircraft headsets) emphasizes the importance of flow. The effect on radio pop programme form [is] a stress on continuity achieved through the use of fades, voice-over links, twin-turntable mixing and connecting jingles."
Fade
A fade can be constructed so that the motion of the control (linear or rotary) from its start to end points affects the level of the signal in a different manner at different points in its travel. If there are no overlapping regions on the same track, regular fade (pre-fade / post-fade) should be used. A smooth fade is one that changes according to the logarithmic scale, as faders are logarithmic over much of their working range of 30-40 dB. If the engineer requires one region to gradually fade into another on the same track, a crossfade would be more suitable. If however the two regions are on different tracks, fade-ins and fade-outs will be applied. A fade-out can be accomplished without letting the sound's distance increase, however this is also something it can do. The perceived distance increase can be attributed to a diminishing level of timbral detail, not the result of a decreasing dynamic level. A listener's interest can be withdrawn from a sound that is faded at the lower end since the ear accepts a more prompt rounding off. The fade-in can be used as a device that separates the listener from the scene. An example of a mini fade out, of about a second or two, is a sustained bass note left to die down.
Shapes
The shape of a regular fade and a crossfade can be shaped by an audio engineer. Shape implies that you can change the rate at which the level change occurs over the length of the fade. Different types of preset fades shapes include linear, logarithmic, exponential and S-curve.
Linear
The simplest of fade curves is the linear curve and it is normally the default fade. It takes a straight line and introduces a curve. This curve represents an equal degree by which the gain increases or decreases during the length of the fade. A linear fade-in curve makes it sound as though the volume increases sharply at the beginning, and more gradually towards the end. The same principle applies on a fade-out where a gradual drop in volume can be perceived in the beginning, and the fade gets more abrupt towards the end. Because of the initial drop in perceived volume, the linear shape is ideal if there is a natural ambience or reverb present in the audio. When applied it shortens the ambience. Also if the music requires an accelerating effect, this linear curve can also be applied. This type of fade is not very natural sounding. The principle of a linear crossfade is: at the beginning of the fade the perceived volume drops more quickly, one can see at the halfway point (in the middle of the crossfade) that the perceived volume drops below 50%. This is a very noticeable drop in volume. Also if the control can move from position 0 to 100, and the percentage of the signal that is allowed to pass equals the position of the control (i.e. 25% of the signal is allowed to pass when the control is 25% of the physical distance from the 0 point to the 100 point). At the midpoint of the fade the effect of a linear crossfade is that both the sounds are below half of their maximum perceived volume; and as a result the sum of the two fades will be below the maximum level of either. This is not applicable when the two sounds are on different levels and the crossfade time is long enough. In turn if the crossfade is short (for example on a single note) the dip of the volume in the middle of the crossfade can be quite noticeable.
The level of the signal as a function of time, , after applying a linear fade-in can be modeled as follows:
where:
is the original level of the signal,
is any time in the fade,
is the start time of the fade,
is the end time of the fade.
Similarly, the level after applying a linear fade-out can be modeled as follows:
Logarithmic
Another type of curve is called the logarithmic ratio (also known as audio taper), or an inverse-logarithmic ratio. This curve more closely matches human hearing, with finer control at lower levels, increasing dramatically past the 50% point. Since the perceived volume of a sound has a logarithmic relationship with its level, the logarithmic fade sounds consistent and smooth over the whole duration of the fade. This makes this curve useful for fading standard pieces of music. It is best used on a long fade-out since the fade has a perceived linear nature. Also, a fade-out sounds very neutral when incorporated to parts of music with natural ambience. In crossfades, this type of curve sounds very natural. When this curve is applied the perceived volume of the fade's midpoint is at about 50% of the maximum – when the two sections are summed the output volume is fairly constant.
Exponential
The exponential curve shape is in many ways the precise opposite of the logarithmic curves. The fade-in works as follows: it increases in volume slowly and then it shoots up very quickly at the end of the fade. The fade-out drops very quickly (from the maximum volume) and then declines slowly again over the duration of the fade. Simply stated, a linear fade could thus be seen as an exaggerated version of an exponential fade in terms of the apparent volume. Thus the impression that would be gathered from an exponential curve's fade would sound as though the sound was rapidly accelerating toward the listener. Natural ambiance can also be repressed by using an exponential fade-out. A crossfade, in the exponential shape, will have a perceivable dip in the middle, which is very undesirable in music and vocals. This depends largely on the length of the crossfade, a long crossfade on ambient sounds can sound perfectly satisfactory (the dip can add a little breath to the music). Exponential crossfades (or a curve with a similar shape) have a smaller drop in the middle of the fade.
S-curve
The S-curve shape has a mixture of qualities from the previously mentioned curves. The level of the sound is 50% at the midpoint, but before and after the midpoint the shape is not linear. There are also two types of S-curves. Traditional S-curve fade-in has attributes of the exponential curve can be seen at the beginning; at the midpoint to the end it is more logarithmic in nature. A traditional S-curve fade-out is logarithmic from the beginning up to the midpoint, then its attributes are based on the exponential curve from the midpoint to the end. This is true for the situation in reverse as well (for both fade-in and fade-out). Crossfading with S-curves diminishes the amount of time that both sounds are playing simultaneously. This ensures that the edits sound like a direct cut when the two edits meet adding an extra smoothness to the edited regions. The second type of S-curve is more applicable to longer crossfades as both signals are audible for as long as possible. There is a short period at the start of each of the crossfades where the outgoing sound drops toward 50% quickly (with the incoming sound rising just as fast to 50%). This acceleration of sound slows and both sounds will appear as if they are at the same level for most of the crossfade before the changeover happens.
Adjustments
DAW's gives one the ability to change the shape of logarithmic, exponential, and S-curve fades and crossfades. Changing the shape of a logarithmic fade will change how soon the sound will rise above 50%, and then how long it takes for the end of the fade-out to drop below 50% once again. With exponential fades the shape change will affect the shape in reverse, to the shape of the logarithmic fade. In the S-curve's traditional form the shape determines how quickly the change can occur and in the type 2 curve the change can determine the time it takes for both the sounds to get to a nearly equal level.
The level after applying an S-curve fade-in can be modeled as follows:
Similarly, the level after applying an S-curve fade-out can be modeled as follows:
It is also possible to apply different fade times to the out and in portions; which a standard crossfade would not allow you to apply. Appropriate fade-in time for a linear fade can be around 500ms; for the fade-out 500ms would also be affective. By having this longer fade it makes sure that everything is gentle as it gives the fade time to blend in and be less abrupt. To clear up plosive sounds created through vocals a fade-in can be used, but now it has to have a very short time of around 10ms. The fade time can always be adjusted by the engineer in order to locate the best time. It is important that the fade does not change the intelligibility or character of the sound too much. When the crossfade is longer than 10ms the standard linear fades are not always the best choice for music editing.
Crossfading
A crossfader on a DJ mixer essentially functions like two faders connected side-by-side, but in opposite directions. A crossfader is typically mounted horizontally, so that the DJ can slide the fader from the extreme left (this provides 100% of sound source A) to the extreme right (this provides 100% of sound source B), move the fader to the middle (this is a 50/50 mix of sources A and B), or adjust the fader to any point in between. It allows a DJ to fade one source out while fading another source in at the same time. This is extremely useful when beatmatching two sources of audio (or more, where channels can be mapped to one of the two sides of the crossfader individually) such as phonograph records, compact discs or digital sources.
The technique of crossfading is also used in audio engineering as a mixing technique, particularly with instrumental solos. A mix engineer will often record two or more takes of a vocal or instrumental part and create a final version which is a composite of the best passages of these takes by crossfading between each track. In the perfect case, the crossfade would keep a constant output level, an important quality for a club DJ who is creating a seamless mix of dance tracks for dancers or a radio DJ seeking to avoid "dead air" (silence) between songs, an error that can cause listeners to change channels. However, there is no standard on how this should be achieved.
There are many software applications that feature virtual crossfades, for instance, burning-software for the recording of audio-CDs. Also many DAW's (Pro Tools, Logic exc.) have this function. Crossfade is normally found on samplers and usually based on velocity. The purpose of a cross-fade it to utilize a smooth changeover between two cut pieces of audio. Velocity crossfading can be incorporated through a MIDI transformation device and where more than one note can be assigned to a given pad (note) on the MIDI keyboard; velocity crossfading may be available.
These types of crossfades (those that are based on note velocity) allow two (even more) samples to be assigned to one note or range of notes. This requires both a loud and soft sample; the reason for this is Timbre change. This type of crossfade is quite subtle depending on the proportion of the received note velocity value of the loud and soft sample.
Crossfading usually involves the sounding of a combination of one or two sounds at the same time. Crossfades can either be applied to a piece of music in real time, or can be pre-calculated. While crossfading one does not want the second part of the fade to start playing before the first part is finished; one wants the overlapping parts to be as short as possible. If edit regions are not trimmed to a zero-crossing point one will get unwelcome pops in the middle. A sound at the lowest velocity can fade into a sound of a higher velocity, in the order of: first the first sound then the second. All possible without fading out the sounds that are already present. This in turn is a form of Layering that can be used in the mix. The same effect (as was created with velocity) can be applied to a controller. This allows continued monitored control; the crossfading function can also be controlled on some instruments by the keyboard position. These sounds on the MIDI keyboard can be programmed.
A crossfade can either be used between two unrelated pieces of music or between two sounds that are similar; in both of these cases, one would like the sound to be one continuous sound without any bumps. When applying a crossfade between two very different pieces of music (relating to both tone and pitch), one could simply use a crossfade between the two pieces, make a few minor adjustments. This is because the two sounds are different from one another. In the case of a crossfade between two sounds, that are similar, phase-cancellation can become an issue. The two sounds that are crossfaded should be brought into comparison with one another. If both sounds are moving upward they will have a cumulative effect - when added together, this is what one wants. What is not desirable is when both sounds are moving in a different direction, since this can lead to cancelations. This leads to no sound on areas where the amplitudes cancel out one another; there will thus be silence in the middle of the crossfade. This occurrence is rare though since the parameters have to be the same. Commonly a crossfade will result in a gradual reduction in the amount of the sample whose pitch is lower, and an increase will be found on the pitch that is higher. The longer a crossfade, the more likely a problem will occur. One also does not want the effect of the crossfade to be very prominent in the middle of the notes, since if different notes are between the edit point there will be a time when both of the sounds can be heard simultaneously. This overlapping is not expected from a normal singing voice, no reference to Overtone singing.
While DJ pioneers such as Francis Grasso had used basic faders to transition between two records as far back as the late 1960s, they typically had separate faders for each channel. Grandmaster Flash is often credited with the invention of the first crossfader by sourcing parts from a junkyard in the Bronx. It was initially an on/off toggle switch from an old microphone that he transformed into a left/right switch which allowed him to switch from one turntable to another, thereby avoiding a break in the music. However the earliest commercial documented example was designed by Richard Wadman, one of the founders of the British company Citronic. It was called the model SMP101, made about 1977, and had a crossfader that doubled as a L/R balance control or a crossfade between two inputs.
Crossfade shapes
When crossfading two signals that are being combined (mixed), the two fade curves can employ any of the shapes listed above (see #Shapes), such as linear, exponential, S-curve, etc. When the goal is to have the perceived loudness of the combined mix signal stay fairly constant across the full range of the mix, special shapes must be used, called "equal power" (or "constant power") shapes. Equal power shapes are based on audio power principles, particularly the fact that the power of an audio signal is proportional to the square of the amplitude. Many equal power shapes have the property that the midpoint of the mix provides an amplitude multiplier of 0.707 (square root of one half) for both signals. A variety of equal power shapes are available, and the optimal shape will generally depend on the amount of correlation between the two signals. An example pair of curves that keep power equal across the mix are and (where m is mix and ranges from 0 to 1).
Equal power shapes typically have the sum of their curves (in the middle of the mix range) exceeding the nominal maximum amplitude (1.0), which may produce clipping in some contexts. If that is a concern, then "equal gain" (or "constant gain") shapes should be used (which may be linear or curved) that are designed so the two curves always sum to 1.
In the digital signal processing realm, the term "power curve" is often used to designate crossfade shapes, particularly for equal power shapes.
Fader
A fader is any device used for fading, especially when it is a knob or button that slides along a track or slot. It is principally a variable resistance or potentiometer also called a ‘pot’. A contact can move from one end to another. As this movement takes place the resistance of the circuit can either increase or decrease. At one end the resistance of the scale is at 0 and at the other side it is infinite. A. Nisbett explains the fader law as follows in his book called The Sound studio:"The ‘law’ of the fader is near-logarithmic over much of its range, which means that a scale of decibels can be made linear (or close to it) over a working range of perhaps 60 dB. If the resistance were to increase according to the same law beyond this, it would be twice as long before reaching a point where the signal is negligible. But the range below -50 dB is of little practical use, so here the rate of fade increases rapidly to the final cut-off".
A knob which rotates is usually not considered a fader, although it is electrically and functionally equivalent. Some small mixers use knobs rather than faders, as do a small number of DJ mixers designed for club DJs who are creating seamless mixes of songs. A fader can be either analogue, directly controlling the resistance or impedance to the source (e.g. a potentiometer); or digital, numerically controlling a digital signal processor (DSP). Analogue faders are found on mixing consoles. A fader can also be used as a control for a voltage controlled amplifier, which has the same effect on the sound as any other fader, but the audio signal does not pass through the fader itself.
Digital
Digital faders are also referred to as virtual faders, since they can be viewed on the screen of a digital audio workstation. Modern high end digital mixers often feature "flying faders", faders with piezo-electric actuators attached; such faders can be multi-use and will jump to the correct position for a selected function or saved setting. Flying faders can be automated, so that when a timecode is presented to the equipment, the fader will move according to a previously performed path. Also called an automated fader, as it recalls the movement of the channel faders in time. A full-function automation system will continuously scan the console, many times per second, in order to incorporate new settings. While this scan is in progress, the stored representation of the previous scan will be compared to that of the fader's current position. If the fader's position has changed, the new position will be identified, thus resulting in a spurt of data.
The console's computer will update the console's controls on playback. This will be done from memory at the same speed. The advantage of working with mix automation is that only one engineer can perform the job with minimal effort; it can be set up or recorded beforehand to make it even simpler. An example of this is when Ken Hamman installed linear faders that made it possible for him to alter several channels with one hand while mixing, thus he assumed an interactive role in the process of recording. This type of fader level adjustment is also called ‘riding’ the fader.
Types
Many DJ equipment manufacturers offer different mixers for different purposes, with different fader styles, e.g., "scratching", beatmixing, and cut mixing. High-priced mixers often have crossfade curve switches allowing the DJ to select the type of crossfade necessary. Experienced DJs are also able to crossfade between tracks using the channel faders.
Pre-fader, post-fader
On a mixer with auxiliary send mixes, the send mixes are configured pre-fader or post-fader. If a send mix is configured pre-fader, then changes to the main channel strip fader does not affect the send mix. In live sound reinforcement, this is useful for stage monitor mixes where changes in the Front of House channel levels would distract the musicians. In recording and post production, configuring a send to be pre-fader allows the amount of audio sent to the aux bus to remain unaffected by the individual track fader, thus not disturbing the stability of the feed that is being sent to the musicians. If a send mix is configured post-fader, then the level sent to the send mix follows changes to the main channel strip fader. This is useful for reverberation and other signal processor effects. An example of this is when an engineer would like to add some delay to the vocals – the fader can thus be used to adjust the amount of delay added.
Pre-fader listen (PFL), after-fader listen (AFL)
Pre-fader listen and After-fader listen are functions found on a primary monitor function.
On an analogue mixing console, the PFL (pre-fader listen) switch routes the incoming signal of a channel to a PFL bus. This bus is sent to the monitor mix and/or the headphones mix, allowing to monitor an incoming signal before it is send to the main output. When the mixer is equipped with VU meters, the PFL allows to visually monitor an audio source without hearing it and adjust its input gain.
This pre-fade listen is valuable since it allows one to listen through headphones in order to hear what the pre-faded part sounds like, while the studio loudspeaker is being used to monitor the rest of the program.
Pre-fade listen can also be used for talkback as well as to listen to channels before they have been faded. After-fade listen only gets its information later. The choice of listen or level will depend on the user's interest: either with the quality and/or content of the signal or with the signal's level. PFL takes place just before the fader and has a joint channel and monitoring function. PFL sends the channel's signal path to the pre-fade bus. The bus is picked up in the monitor module and made accessible as a substitute signal that is sent to the mixer output. Automatic PFL has been made available, almost universally, and no longer needs to be selected beforehand.
Pre-fade listen can also be incorporated in radio stations and serves as a vital tool. This function allows the radio presenter to listen to the source before it is faded on air; allowing the presenter to check the source's incoming level and make sure it is accurate. It is also valuable since live radio broadcasts can fall apart without it as they will not be able to monitor the sound. After-fader listen is not as useful in live programs.
See also
Beatmatching
Beatmixing
Gapless playback
Harmonic mixing
References
Audio mixing
Audio engineering
Sound recording
DJing
Articles containing video clips | Fade (audio engineering) | Engineering | 6,520 |
69,144,535 | https://en.wikipedia.org/wiki/DIMPL | DIMPL (Discovery of Intergenic Motifs PipeLine) is a bioinformatic pipeline that enables the extraction and selection of bacterial GC-rich intergenic regions (IGRs) that are enriched for structured non-coding RNAs (ncRNAs). The method of enriching bacterial IGRs for ncRNA motif discovery was first reported for a study in "Genome-wide discovery of structured noncoding RNAs in bacteria".
DIMPL pipeline automates the process of total genome analysis by extracting IGRs, filtering them by length and nucleic acid composition, and collecting the data necessary to identify candidate motifs and assign their possible functions. DIMPL pipeline provides reproducible techniques for identifying genomic regions enriched for ncRNA through support vector machine (SVM) classifiers. It can be used to look for nucleic acid and protein motifs, including riboswitch-like elements, upstream open reading frames (uORFs), short open reading frames (sORFs), ribosomal protein leader sequences, selfish genetic elements and other structured RNA motifs of unknown function.
DIMPL uses various sequence analysis resources, including:
Rfam database, as a reference of known RNA families
BLASTX search tool, to eliminate unannotated protein coding regions
INFERNAL package, to search the IGSs sequences
CMfinder, to look for possible RNA secondary structure features
R-scape software and R2R drawing algorithm, to generate the consensus model
RNAcode, to look for the presence of coding regions
GenomeView, to visualize the genetic context of the RNA motif
RNA motifs discovered using DIMPL include HMP-PP riboswitch, icd-II ncRNA motif, carA ncRNA motif, ldh2 ncRNA motif, among others.
References
Bioinformatics
Computational biology | DIMPL | Engineering,Biology | 370 |
11,421,292 | https://en.wikipedia.org/wiki/Mir-399%20microRNA%20precursor%20family | mir-399 is a microRNA that was identified in both Arabidopsis thaliana and Oryza sativa computationally and was later experimentally verified. mir-399 is thought to target mRNAs coding for a phosphate transporter. The mature sequence is excised from the 3' arm of the hairpin. There are multiple copies of MIR399 in each plant genome, for example A. thaliana contains six microRNA precursors that all give rise to an almost identical mature miR-399 sequence.
References
Further reading
External links
miRBase family MIPF0000015
MicroRNA
MicroRNA precursor families | Mir-399 microRNA precursor family | Chemistry | 131 |
39,367,145 | https://en.wikipedia.org/wiki/Biological%20aspects%20of%20fluorine | Fluorine may interact with biological systems in the form of fluorine-containing compounds. Though elemental fluorine (F2) is very rare in everyday life, fluorine-containing compounds such as fluorite occur naturally as minerals. Naturally occurring organofluorine compounds are extremely rare. Man-made fluoride compounds are common and are used in medicines, pesticides, and materials. Twenty percent of all commercialized pharmaceuticals contain fluorine, including Lipitor and Prozac. In many contexts, fluorine-containing compounds are harmless or even beneficial to living organisms; in others, they are toxic.
Aside from their use in medicine, man-made fluorinated compounds have also played a role in several noteworthy environmental concerns. Chlorofluorocarbons (CFCs), once major components of numerous commercial aerosol products, have proven damaging to Earth's ozone layer and resulted in the wide-reaching Montreal Protocol; though in truth the chlorine in CFCs is the destructive actor, fluorine is an important part of these molecules because it makes them very stable and long-lived. Similarly, the stability of many organofluorine compounds has raised the issue of biopersistence. Long-lived molecules from waterproofing sprays, for example PFOA and PFOS, are found worldwide in the tissues of wildlife and humans, including newborn children.
Fluorine biology is also relevant to a number of cutting-edge technologies. PFCs (perfluorocarbons) are capable of holding enough oxygen to support human liquid breathing. Organofluorine in the form of its radioisotope 18F is also at the heart of a modern medical imaging technique known as positron emission tomography (PET). A PET scan produces three-dimensional colored images of parts of the body that use a lot of sugar, particularly the brain or tumors.
Dental care
Since the mid-20th century, it has been discerned from population studies (though incompletely understood) that fluoride reduces tooth decay. Initially, researchers hypothesized that fluoride helped by converting tooth enamel from the more acid-soluble mineral hydroxyapatite to the less acid-soluble mineral fluorapatite. However, more recent studies showed no difference in the frequency of caries (cavities) between teeth that were pre-fluoridated to different degrees. Current thinking is that fluoride prevents cavities primarily by helping teeth that are in the very early stages of tooth decay.
When teeth begin to decay from the acid produced by sugar-consuming bacteria, calcium is lost (demineralization). However, teeth have a limited ability to recover calcium if decay is not too far advanced (remineralization). Fluoride appears to reduce demineralization and increase remineralization. Also, there is some evidence that fluoride interferes with the bacteria that consume sugars in the mouth and make tooth-destroying acids. In any case, it is only the fluoride that is directly present in the mouth (topical treatment) that prevents cavities; fluoride ions that are swallowed do not benefit the teeth.
Water fluoridation is the controlled addition of fluoride to a public water supply in an effort to reduce tooth decay in people who drink the water. Its use began in the 1940s, following studies of children in a region where water is naturally fluoridated. It is now used widely in public water systems in the United States and some other parts of the world, such that about two-thirds of the U.S. population is exposed to fluoridated water supplies and about 5.7% of people worldwide. Although the best available evidence shows no association with adverse effects other than fluorosis (dental and, in worse cases, skeletal), most of which is mild, water fluoridation has been contentious for ethical, safety, and efficacy reasons, and opposition to water fluoridation exists despite its widespread support by public health organizations. The benefits of water fluoridation have lessened recently, presumably because of the availability of fluoride in other forms, but are still measurable, particularly for low-income groups. Systematic reviews in 2000 and 2007 showed significant reduction of cavities in children exposed to water fluoridation.
Sodium fluoride, tin difluoride, and, most commonly, sodium monofluorophosphate, are used in toothpaste. In 1955, the first fluoride toothpaste was introduced in the United States. Now, almost all toothpaste in developed countries is fluoridated. For example, 95% of European toothpaste contains fluoride. Gels and foams are often advised for special patient groups, particularly those undergoing radiation therapy to the head (cancer patients). The patient receives a four-minute application of a high amount of fluoride. Varnishes, which can be more quickly applied, exist and perform a similar function. Fluoride is also often present in prescription and non-prescription mouthwashes and is a trace component of foods manufactured using fluoridated water supplies.
Medical applications
Pharmaceuticals
Of all commercialized pharmaceutical drugs, twenty percent contain fluorine, including important drugs in many different pharmaceutical classes. Fluorine is often added to drug molecules during drug design, as even a single atom can greatly change the chemical properties of the molecule in desirable ways.
Because of the considerable stability of the carbon–fluorine bond, many drugs are fluorinated to delay their metabolism, which is the chemical process in which the drugs are turned into compounds that allows them to be eliminated. This prolongs their half-lives and allows for longer times between dosing and activation. For example, an aromatic ring may prevent the metabolism of a drug, but this presents a safety problem, because some aromatic compounds are metabolized in the body into poisonous epoxides by the organism's native enzymes. Substituting a fluorine into a para position, however, protects the aromatic ring and prevents the epoxide from being produced.
Adding fluorine to biologically active organic compounds increases their lipophilicity (ability to dissolve in fats), because the carbon–fluorine bond is even more hydrophobic than the carbon–hydrogen bond. This effect often increases a drug's bioavailability because of increased cell membrane penetration. Although the potential of fluorine being released in a fluoride leaving group depends on its position in the molecule, organofluorides are generally very stable, since the carbon–fluorine bond is strong.
Fluorines also find their uses in common mineralocorticoids, a class of drugs that increase the blood pressure. Adding a fluorine increases both its medical power and anti-inflammatory effects. Fluorine-containing fludrocortisone is one of the most common of these drugs. Dexamethasone and triamcinolone, which are among the most potent of the related synthetic corticosteroid class of drugs, contain fluorine as well.
Several inhaled general anesthetic agents, including the most commonly used inhaled agents, also contain fluorine. The first fluorinated anesthetic agent, halothane, proved to be much safer (neither explosive nor flammable) and longer-lasting than those previously used. Modern fluorinated anesthetics are longer-lasting still and almost insoluble in blood, which accelerates the awakening. Examples include sevoflurane, desflurane, enflurane, and isoflurane, all hydrofluorocarbon derivatives.
Prior to the 1980s, antidepressants altered not only serotonin uptake but also the uptake of altered norepinephrine; the latter caused most of the side effects of antidepressants. The first drug to alter only the serotonin uptake was Prozac; it gave birth to the extensive selective serotonin reuptake inhibitor (SSRI) antidepressant class and is the best-selling antidepressant. Many other SSRI antidepressants are fluorinated organics, including Celexa, Luvox, and Lexapro. Fluoroquinolones are a commonly used family of broad-spectrum antibiotics.
Scanning
Compounds containing fluorine-18, a radioactive isotope that emits positrons, are often used in positron emission tomography (PET) scanning, because the isotope's half-life of about 110 minutes is usefully long by positron-emitter standards. One such radiopharmaceutical is 2-deoxy-2-(18F)fluoro-D-glucose (generically referred to as fludeoxyglucose), commonly abbreviated as 18F-FDG, or simply FDG. In PET imaging, FDG can be used for assessing glucose metabolism in the brain and for imaging cancer tumors. After injection into the blood, FDG is taken up by "FDG-avid" tissues with a high need for glucose, such as the brain and most types of malignant tumors. Tomography, often assisted by a computer to form a PET/CT (CT stands for "computer tomography") machine, can then be used to diagnose or monitor treatment of cancers, especially Hodgkin's lymphoma, lung cancer, and breast cancer.
Natural fluorine is monoisotopic, consisting solely of fluorine-19. Fluorine compounds are highly amenable to nuclear magnetic resonance (NMR), because fluorine-19 has a nuclear spin of , a high nuclear magnetic moment, and a high magnetogyric ratio. Fluorine compounds typically have a fast NMR relaxation, which enables the use of fast averaging to obtain a signal-to-noise ratio similar to hydrogen-1 NMR spectra. Fluorine-19 is commonly used in NMR study of metabolism, protein structures and conformational changes. In addition, inert fluorinated gases have the potential to be a cheap and efficient tool for imaging lung ventilation.
Oxygen transport research
Liquid fluorocarbons have a very high capacity for holding gas in solution. They can hold more oxygen or carbon dioxide than blood does. For that reason, they have attracted ongoing interest related to the possibility of artificial blood or of liquid breathing.
Blood substitutes are the subject of research because the demand for blood transfusions grows faster than donations. In some scenarios, artificial blood may be more convenient or safe. Because fluorocarbons do not normally mix with water, they must be mixed into emulsions (small droplets of perfluorocarbon suspended in water) in order to be used as blood. One such product, Oxycyte, has been through initial clinical trials.
Possible medical uses of liquid breathing (which uses pure perfluorocarbon liquid, not a water emulsion) involve assistance for premature babies or for burn patients (if normal lung function is compromised). Both partial and complete filling of the lungs have been considered, although only the former has undergone any significant tests in humans. Several animal tests have been performed and there have been some human partial liquid ventilation trials. One effort, by Alliance Pharmaceuticals, reached clinical trials but was abandoned because of insufficient advantage compared to other therapies.
Nanocrystals represent a possible method of delivering water- or fat-soluble drugs within a perfluorochemical fluid. The use of these particles is being developed to help treat babies with damaged lungs.
Perfluorocarbons are banned from sports, where they may be used to increase oxygen use for endurance athletes. One cyclist, Mauro Gianetti, was investigated after a near-fatality where PFC use was suspected. Other posited applications include deep-sea diving and space travel, applications that both require total, not partial, liquid ventilation. The 1989 film The Abyss depicted a fictional use of perfluorocarbon for human diving but also filmed a real rat surviving while cooled and immersed in perfluorocarbon. (See also list of fictional treatments of perfluorocarbon breathing.)
Agrichemicals
An estimated 30% of agrichemical compounds contain fluorine. Most of them are used as poisons, but a few stimulate growth instead.
Sodium fluoroacetate has been used as an insecticide, but it is especially effective against mammalian pests. The name "1080" refers to the catalogue number of the poison, which became its brand name. Fluoroacetate is similar to acetate, which has a pivotal role in the Krebs cycle (a key part of cell metabolism). Fluoroacetate halts the cycle and causes cells to be deprived of energy. Several other insecticides contain sodium fluoride, which is much less toxic than fluoroacetate. Insects fed 29-fluorostigmasterol use it to produce fluoroacetates. If a fluorine is transferred to a body cell, it blocks metabolism at the position occupied.
Trifluralin was widely used in the 20th century, for example, in over half of U.S. cotton field acreage in 1998. Because of its suspected carcinogenic properties some Northern European countries banned it in 1993. As of 2015, the European Union has banned it, although Dow made a case to cancel the decision in 2011.
Biochemistry
Biologically synthesized organofluorines are few in number, although some are widely produced. The most common example is fluoroacetate, with an active poison molecule identical to commercial "1080". It is used as a defense against herbivores by at least 40 green plants in Australia, Brazil, and Africa; other biologically synthesized organofluorines include ω-fluoro fatty acids, fluoroacetone, and 2-fluorocitrate. In bacteria, the enzyme adenosyl-fluoride synthase, which makes the carbon–fluorine bond, has been isolated. The discovery was touted as possibly leading to biological routes for organofluorine synthesis.
Fluoride is considered a semi-essential element for humans: not necessary to sustain life, but contributing (within narrow limits of daily intake) to dental health and bone strength. Daily requirements for fluorine in humans vary with age and sex, ranging from 0.01 mg in infants below 6 months to 4 mg in adult males, with an upper tolerable limit of 0.7 mg in infants to 10 mg in adult males and females. Small amounts of fluoride may be beneficial for bone strength, but this is an issue only in the formulation of artificial diets. (See also fluoride deficiency.)
Hazards
Fluorine gas
Elemental fluorine is highly toxic. Above a concentration of 25 ppm, it causes significant irritation while attacking the eyes, airways and lungs and affecting the liver and kidneys. At a concentration of 100 ppm, human eyes and noses are seriously damaged. People can be exposed to fluorine in the workplace by breathing it in, skin contact, or eye contact. The Occupational Safety and Health Administration (OSHA) has set the legal limit (Permissible exposure limit) for fluorine exposure in the workplace as 0.1 ppm (0.2 mg/m3) over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 0.1 ppm (0.2 mg/m3) over an 8-hour workday. At levels of 25 ppm, fluorine is immediately dangerous to life and health.
Hydrofluoric acid
Hydrofluoric acid, the water solution of hydrogen fluoride (HF), is a contact poison. Even though it is from a chemical perspective a relatively weak acid, it is far more dangerous than conventional strong mineral acids, such as nitric acid, sulfuric acid, or hydrochloric acid. Owing to its lesser chemical dissociation in water (remaining a neutral molecule), hydrogen fluoride penetrates tissue more quickly than typical acids. Poisoning can occur readily through the skin or eyes or when inhaled or swallowed. From 1984 to 1994, at least nine workers died in the United States from accidents with HF.
Once in the blood, hydrogen fluoride reacts with calcium and magnesium, resulting in electrolyte imbalances, potentially including hypocalcemia. The consequent effect on the heart (cardiac arrhythmia) may be fatal. Formation of insoluble calcium fluoride also causes severe pain. Burns with areas larger than 160 cm2, about the size of a man's hand, can cause serious systemic toxicity.
Symptoms of exposure to hydrofluoric acid may not be immediately evident, with an eight-hour delay for 50% HF and up to 24 hours for lower concentrations. Hydrogen fluoride interferes with nerve function, meaning that burns may not initially be painful. If the burn has been initially noticed, then HF should be washed off with a forceful stream of water for ten to fifteen minutes to prevent its further penetration into the body. Clothing used by the person burned may also present a danger. Hydrofluoric acid exposure is often treated with calcium gluconate, a source of Ca2+ that binds with the fluoride ions. Skin burns can be treated with a water wash and 2.5 percent calcium gluconate gel or special rinsing solutions. Because HF is absorbed, further medical treatment is necessary. Calcium gluconate may be injected or administered intravenously. Use of calcium chloride is contraindicated and may lead to severe complications. Sometimes surgical excision of tissue or amputation is required.
Fluoride ion
Soluble fluorides are moderately toxic. For sodium fluoride, the lethal dose for adults is 5–10 g, which is equivalent to 32–64 mg of elemental fluoride per kilogram of body weight. The dose that may lead to adverse health effects is about one fifth of the lethal dose. Chronic excess fluoride consumption can lead to skeletal fluorosis, a disease of the bones that affects millions in Asia and Africa.
The fluoride ion is readily absorbed by the stomach and intestines. Ingested fluoride forms hydrofluoric acid in the stomach. In this form, fluoride crosses cell membranes and then binds with calcium and interferes with various enzymes. Fluoride is excreted through urine. Fluoride exposure limits are based on urine testing, which is used to determine the human body's capacity for ridding itself of fluoride.
Historically, most cases of fluoride poisoning have been caused by accidental ingestion of insecticides containing inorganic fluoride. Most calls to poison control centers for possible fluoride poisoning come from the ingestion of fluoride-containing toothpaste. Malfunction of water fluoridation equipment has occurred several times, including an Alaskan incident that sickened nearly 300 people and killed one.
Biopersistence
Because of the strength of the carbon–fluorine bond, organofluorines endure in the environment. Perfluorinated compounds (PFCs) have attracted particular attention as persistent global contaminants. These compounds can enter the environment from their direct uses in waterproofing treatments and firefighting foams or indirectly from leaks from fluoropolymer production plants (where they are intermediates). Because of the acid group, PFCs are water-soluble in low concentrations. While there are other PFAAs, the lion's share of environmental research has been done on the two most well-known: perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). The U.S. Environmental Protection Agency classifies these materials as "emerging contaminants" based on the growing but still incomplete understanding of their environmental impact.
Trace quantities of PFCs have been detected worldwide, in organisms from polar bears in the Arctic to the global human population. Both PFOS and PFOA have been detected in breast milk and the blood of newborns. A 2013 review showed widely varying amounts of PFOS and PFOA in different soils and groundwater, with no clear pattern of one chemical dominating. PFC concentrations were generally higher in areas with more human population or industrial activity, and areas with more PFOS generally also had more PFOA. the two chemicals have been found at different concentrations in different populations; for example, one study showed more PFOS than PFOA in Germans, while another study showed the reverse for Americans. PFCs may be starting to decrease in the biosphere: one study indicated that PFOS levels in wildlife in Minnesota were decreasing, presumably because 3M discontinued its production.
In the body, PFCs bind to proteins such as serum albumin. Their tissue distribution in humans is unknown, but studies in rats suggest it is present mostly in the liver, kidney, and blood. They are not metabolized by the body but are excreted by the kidneys. Dwell time in the body varies greatly by species. Rodents have half-lives of days, while in humans they remain for years. Many animals show sex differences in the ability to rid the body of PFAAs, but without a clear pattern. Gender differences of half lives vary by animal species.
The potential health impact of PFCs is unclear. Unlike chlorinated hydrocarbons, PFCs are not lipophilic (stored in fat), nor genotoxic (damaging genes). Both PFOA and PFOS in high doses cause cancer and the death of newborns in rodents. Studies on humans have not been able to prove an impact at current exposures. Bottlenose dolphins have some of the highest PFOS concentrations of any wildlife studied; one study suggests an impact on their immune systems.
The biochemical causes of toxicity are also unclear and may differ by molecule, health effect, and even animal. PPAR-alpha is a protein that interacts with PFAAs and is commonly implicated in contaminant-caused rodent cancers.
Less fluorinated chemicals (i.e. not perfluorinated compounds) can also be detected in the environment. Because biological systems do not metabolize fluorinated molecules easily, fluorinated pharmaceuticals like antibiotics and antidepressants can be found in treated city sewage and wastewater. Fluorine-containing agrichemicals are measurable in farmland runoff and nearby rivers.
See also
Fluorine absorption dating (a relative method for archeological dating of bone or other organics)
Fluorine deficiency
Fluoride toxicity
References
Sources
External links
A strong acid it is not, but deadly it is... (Podcast on fluorine, note the first few minutes discussion of a fatal HF burn.)
Fluorine
Biochemistry
Biology and pharmacology of chemical elements | Biological aspects of fluorine | Chemistry,Biology | 4,785 |
68,730,641 | https://en.wikipedia.org/wiki/Time%20in%20the%20Gambia | Time in the Gambia is given by a single time zone, denoted as Greenwich Mean Time (GMT; UTC+00:00). Adopted in 1918, the Gambia has never observed daylight saving time (DST).
IANA time zone database
In the IANA time zone database, the Gambia is given one zone in the file zone.tab – Africa/Banjul. "GM" refers to the country's ISO 3166-1 alpha-2 country code. Data for the Gambia directly from zone.tab of the IANA time zone database; columns marked with * are the columns from zone.tab itself:
See also
List of time zones by country
List of UTC time offsets
References
External links
Current time in the Gambia at Time.is
Time in the Gambia at TimeAndDate.com
Time by country
Geography of the Gambia
Time in Africa | Time in the Gambia | Physics | 175 |
49,292,680 | https://en.wikipedia.org/wiki/Stair%20tread | A stair tread is the horizontal portion of a set of stairs on which a person walks. The tread can be composed of wood, metal, plastic, or other materials. In residential settings, treads can be covered in carpeting. Stair treads can come in non-slip varieties, particularly in commercial or industrial locations.
Styles of tread
There are a number of different styles of tread:
Mid flight treads.
Straight or flier. A standard oblong shaped tread. used in a straight flight.
Diminishing flier. Set into the straight section of flight before a turn, with one end narrower than the other Used to change the pitch of the handrail before a 180º turn.
Winder. wider at one end, used to turn the flight.
Kite winder. A quadrilateral shaped tread, used in the corner of a turn: hence the kite name.
Feature or starting treads.
These treads are used to embellish the start of a flight of stairs, they may have either a straight front to them or a commode/curved front to enhance them further.
Curtail. An ornate tread that follows the spiral of a volute handrail, the back of the tread will cut into itself and then return along the flight.
Bullnose. A straight tread with the front corners rounded off.
"D" ends. So called as they look like a D shape attached to the end of the tread. A common style that may be carried up the flight for a number of treads.
Tower.The tower feature is a cylindrical addition to the front corner of a tread, intended for setting a newel post onto, the tower may be positioned dependent on the handrail termination.
Commode front. The addition of a curve to the front of a tread to create a more decorative feature.
USAB & ADA compliance
According to the United States Access Board, stair treads in buildings shall have uniform tread depths that are 11 inches, or 280 mm, at minimum. Treads are not permitted to have a slope steeper than 1:48.
All stair tread installations must comply with Regulation 302 of the ADA Standards for Accessible Design. The regulation states that the surface of the [tread] must be firm, stable, and slip-resistant.
Notable sets of stair treads
The Dylan's Candy Bar flagship location features a stair case consisting of 53 resin stair treads and three landings that are embedded with real candy and equipped with inserted abrasion strips.
China's first children's design museum, Kids Museum of Glass, has alternating black and white stair treads on its central staircase, earning the nickname "The Piano Staircase".
As part of the Underground Shopping Center Public Art Project, the Seoul Metropolitan Facilities Management Corporation built a piano staircase in the underground passage at Euljiro 1-ga Station. Each step lit up and played a note as it was walked on.
IDEO Labs' interns created a musical staircase during summer of 2011. Each tread played a different sound when stepped on.
Johns Hopkins University students turned a Hackerman Hall staircase into a piano, with a new note per step. The Hopkins Robotics Club modified the staircase so the treads played the C scale.
References
Stairs
Stairways
Architectural elements
Building engineering
Safety codes | Stair tread | Technology,Engineering | 664 |
21,708,401 | https://en.wikipedia.org/wiki/Creativity%20%28religion%29 | Creativity, historically known as the (World) Church of the Creator, is an atheistic (nontheistic) white supremacist new religious movement espousing white separatism, antitheism, antisemitism, anti-Christian sentiment, scientific racism, homophobia, and religious / philosophical naturalism. Creativity is an openly-racist religion urging for "White pride" and has been classified as a hate group by the Southern Poverty Law Center and the Anti-Defamation League. It was founded in Lighthouse Point, Florida, United States, by Ben Klassen as the Church of the Creator in 1973. It now has a presence in several states of the U.S. as well as Australia, Eastern Europe, and the United Kingdom.
Creativity is promoted by two organizations: the Creativity Alliance (CA also known as the Church of Creativity), and the Creativity Movement. The two groups have common origins, both being created in 2003 after Klassen's successor Matthew F. Hale (who had renamed the organisation New Church of the Creator) was arrested and sentenced to 40 years in prison.
Creativity claims a naturalistic and racialistic worldview, based on the "survival, expansion and advancement of the White race", according to what the group classifies as the "eternal laws of nature, the experience of history, on logic and common sense". Members of the group believe in a "racial holy war" between "white and non-white races", such as Jews, black people, and mixed-race people.
History
The religion was originally founded as the "Church of the Creator" by Ben Klassen in 1973, when he self-published Nature's Eternal Religion. Adherents of Creativity refer to themselves as Creators, a term derived from Hitler's autobiographical manifesto Mein Kampf, wherein his classification of "races" falls into three categories, with the "white race", deemed the "Master race", termed the "creators". Klassen attempted to recruit neo-Nazis into the church because, apart from disagreements over Nazism's embrace of Positive Christianity, its insistence on nationalism (rather than racialism), anti-Slavic and other sentiments against non-Germanic European ethnic groups, Klassen highly revered Adolf Hitler as a "great pioneer" and Nazism as admirable in many contexts. He developed a rapport with National Alliance leader William Luther Pierce; he met Pierce twice in 1975, and they maintained an "on and off" relationship for the next 18 years. According to Klassen, he "never did understand the logic of what [Pierce] called his Cosmotheism religion ... it has not been of any significance as far as our common goal of promoting White racial solidarity was concerned." In Trials, Tribulations, and Triumphs, Klassen called Pierce "a great man and an outstanding intellectual thinker, and ... one of us."
In 1982, Klassen established a Creativity headquarters in Otto, North Carolina. Although his family expected resistance from local residents, Klassen wrote: "We were not quite prepared for the viciousness of the onslaught by the local paper." Opposition grew, and a May 13, 1982 Franklin Press headline read: "Pro-Hitler, anti-Christ Leader Headquarters Here".
In August 1993, Klassen committed suicide at the age of 75 on the grounds of the Creativity headquarters in Otto by taking an overdose of sleeping pills. His motives were not explained by him at the time but writers studying neo-Nazi groups have suggested that Klassen's reason for taking his own life involved the possible depression caused by the death of his wife, the legal and financial issues his church endured during the years 1992 and 1993 leading up to his death and the fact he was diagnosed with cancer. Unlike other religions such as Judaism or Christianity, Klassen's Creativity religion does not believe that suicide is a sin and in circumstances such as that faced by its founder Klassen in the early 1990s, is considered a suitable way to die. Klassen was buried on his Creativity headquarters at Otto with his grave in an area that he had already previously designated as "Ben Klassen Memorial Park".
In 1996, Matthew F. Hale, along with other ministers of the original Church of the Creator, formed a successor group known as the "World Church of the Creator". Hale's right to use the name "Church of the Creator" in the United States was lost to the Church of the Creator, an unaffiliated religious organization based in Ashland, Oregon, in a trademark infringement case.
In January 2003, Hale was arrested and charged with attempting to direct security chief Anthony Evola to murder judge Joan Lefkow; he was convicted and sentenced to 40 years' imprisonment. Following the demise of the World Church of the Creator after Hale's arrest in 2003, there formed two distinct groups, known as "The Creativity Movement" and the "Creativity Alliance" or "Church of Creativity". An Australian man, Colin Campbell, co-founded Creativity Alliance.
Beliefs and membership
White separatism is fundamental to Creativity, and as such, adherents of it are taught to hate non-whites and avoid social interactions with them. Adherents of the religion are also expected to refute homosexuality, miscegenation and complaining. Membership in the Creativity Movement is restricted to persons whose genetic heritage is "wholly or predominantly" from Europe, or members of the white race, regardless of where they reside.
The leader of the entire Creativity religion is called the "Pontifex Maximus", Latin for "Greatest Priest" and a title derived from its usage from Ancient Rome. The first Pontifex Maximus in the Creativity religion was Klassen himself.
Creativity has "Sixteen Commandments" and "Five Fundamental Beliefs", which adherents are supposed to recite five times a day, including the belief that "their race is their religion", their belief that the white race is "nature's finest creation", their belief that racial loyalty is the "greatest honor" and their belief that racial treason is the "worst crime", their belief that anything which is beneficial to white people is good and their belief that anything which is detrimental to white people is bad, and their belief that white people should avoid business dealings with Jews and refuse to "employ niggers or other coloreds". Klassen's Little White Book declares that Creativity is the "one and only, true and revolutionary White racial religion", repudiating other racist religions such as Christian Identity and Wotanism.
Klassen was a racist who hated all black people and was very open about his contempt for blacks. In public discourse as well as in his writings, Klassen consistently referred to black people with the racial slur "nigger" and required that all followers of his religion use that word to refer to blacks rather than non-derogatory terms such as "black" or "African American". Klassen also condemned other racists who used less offensive terms such as "negro", stating in print that "Furthermore, in looking up the word in Webster's dictionary I found the term 'nigger' very descriptive: 'a vulgar, offensive term of hostility and contempt for the black man'. I can't think of anything that defines better and more accurately what our position... should be... If we are going to be for racial integrity and racial purity... we must take a hostile position toward the nigger. We must give him nothing but contempt."
The religion advocates the belief that American culture is becoming "more decadent", citing an increase in the number of "black crimes, the growing acceptance of homosexuality, interracial marriage, increasing drug use, and the lack of racial identity among white people" as evidence of its increasing decadence. According to the Anti-Defamation League, members believe that Jewish people are working towards the enslavement of all races, and in particular, they believe that the Jews are working towards the "mongrelization of the white race". During the early 2000s, the group was encouraged to move to Central Illinois in order to establish a "Creativity bastion" (i.e., a place where Creators are the majority demographic).
Diet
Klassen was a natural hygienist who recommended a strict fruitarian and raw vegan diet known as "Salubrious Living" which consisted of organically grown fruits, grains, nuts and vegetables. He commented that food should be "uncooked, unprocessed, unpreserved and not tampered with in any other way. This further means it must be organically grown without the use of chemicals." Klassen argued that humans are frugivores and distinguished his fruitarian diet to vegetarianism. In his book The White Man's Bible, he stated that "we are not recommending a vegetarian diet but a frugitarian diet", which included nuts and seeds as a supply of protein. However, Klassen himself did not follow all the rules of his health regime. Historian George Michael has noted that "despite his advocacy of healthy nutrition, some of his associates claimed that in practice Klassen did not actually follow the "salubrious living" regimen, because he often ate red meat and ice cream." (Klassen believed in the full-implementation of Salubrious Living as part of the "advancement-stage" goals of Creativity with the diet being a personal choice for adherents and not as a prerequisite for membership in his group.)
Creativity Alliance continues to advocate Klassen's raw vegan diet and argues against the use of all drugs, including "artificial medications", in favor of "natural remedies". Creativity members are purported to follow their own anti-Semitic version of "kosher" dietary laws in which pork, shellfish and catfish are strictly forbidden.
Afterlife and supernatural
Creativity rejects supernaturalism, affirming a metaphysical naturalist worldview. According to its founder Ben Klassen, a member is "not superstitious and disdains belief in the supernatural... [not giving] credence to, or playing silly games with imaginary spooks, spirits, gods and demons." Members do not believe that Nature is a conscious entity, but hold to a naturalistic pantheist view of "everything [is] in Nature"—"the whole cosmos, the total universe, including its millions of natural laws through space and time".
Members reject the concept of an afterlife believing that individual genetic "immortality" is attained through reproduction and legacy, with a cessation of consciousness of the individual at death. Creativity upholds collectivism over individualism and teaches that life and death on Earth should be viewed in a "rational, fearless manner". Members believe that the purpose of life is "the survival, expansion and advancement" of the white race with "continuance of the individual" attained through heredity and the legacy left to future generations.
Whereas Klassen was classified as an atheist, and Creativity has been labelled atheistic by the press, he objected to the usage of the term considering it a derogatory smear word without meaning employed by believers in what he termed "non-existent spooks in the sky" while stating that the "organized atheist movements" lacked any "positive creed and program of its own to replace the superstitions it seeks to destroy" while stating that most of the atheist movements in existence at the time did not take any pro-white racial stance and that many of them were under "heavy Jewish influence". Citing commonality, Klassen stated that both "atheism and Creativity deplore and denounce any and all supernatural beliefs, claims and superstitions. We do not believe in gods, devils, spooks, spirits, heaven or hell. We denounce all such hocus-pocus as being invented by men, largely for the purpose of controlling their minds and worldly affairs and extracting the utmost financial gain from them."
Racial socialism
The Southern Poverty Law Center classifies Creativity as a neo-Nazi ideology. According to Klassen, Creativity is not a rehash of Nazism; as evidence of this fact, he listed eight differences which exist between the two political ideologies. He adopted the phrase "racial socialism" to describe his political ideology. Klassen was critical of democracy and advocated meritocracy, believing that effective leaders should rule. Under racial socialism, "whites would work together toward common goals but without the massive economic planning in the style of the Soviet Gosplan". He supported a limited market economy, believing that social and economic activities should be in the best interests of white people. Klassen criticized "leftist proclivities" to recruit from the white working class: "All [white] members of the national or racial community ... had an important role to play."
Klassen urged members of Creativity to "work feverishly and aggressively to organize politically, to distribute literature on behalf of the White Race, to promote and foster White solidarity, and to get control of the government and the political machinery of the state by legal means if possible. If this is not possible by legal means, then we must resort to the same means as our forefathers used two hundred years ago to defend their liberty, their property, their homes and their families."
Activism
Creativity engages in proselytism with the stated goal of placing 10 million copies of two books, Nature's Eternal Religion and The White Man's Bible, into the hands of white people as part of its belief in "gird[ing] up for total war". It teaches the white genocide conspiracy theory in support of its perception that shifting population demographics is leading to miscegenation.
According to the Ontario Consultants on Religious Tolerance, the Creativity Movement opposes illegal activity and violence, believing it to be counterproductive. The group's member handbook threatens expulsion from the group for members who commit crimes or encourage others to do so. Despite this, the group has been connected to multiple religiously- and racially-motivated violent crimes. Members of the group view "racial holy war" (Rahowa) as a religious war of racial self-defense. The White Man's Bible states the belief that a Zionist Occupational Government will prevent Creativity from being promoted legally, and tells its readers that "when that stage
arrives (and we can well expect that our Jewish tyrants will push us to the limit), then we must again plan our actions accordingly—and deliberately, carefully and ruthlessly", calling for readers to, "use any means, legal or otherwise, available to us for our own survival," leading to the hunting down and eliminating of the group's "tormentors".
Practices
Holidays
The religion has several holidays. Creators are encouraged to observe them, spending time with their families and friends of the religion:
South Victory Day (January 26): Commemorates the arrival of the First Fleet to the Australian continent in 1788.
Klassen Day (February 20): Anniversary of its founder's birth in 1918.
Founding Day (February 21): Anniversary of the publication of Nature’s Eternal Religion in 1973.
Foundation Day, Rahowa Day (March 20): Anniversary of the foundation of the World Center in 1982 and a reminder of racial war.
Kozel Day, Martyr's Day (September 15): Commemorates Brian Kozel, a movement member who was killed in a fight with Mexicans on this date in 1990.
Festum Album (December 26 – January 1): Week-long celebration of white racial pride, commemorating the massacre at Wounded Knee. December 29, the anniversary of the massacre is also celebrated as "West Victory Day".
Ceremonies
Creativity has four life cycle ceremonies: The Creator Wedding Ceremony, the Creator Child Pledging Ceremony, the Ceremony of Confirmation of Loyalty to the White Race, and The Saying of Goodbyes to our Departed Brethren. Ceremonies are performed by church ministers. At a wedding, the bride and groom exchange vows before "Nature" and the congregation. The pledging ceremony is ideally conducted within two weeks after a child's birth, with both parents pledging to raise their child as a "loyal member of the White Race and faithful to the church." The confirmation ceremony is to ideally performed on the child's 13th birthday. The eulogy ceremony is up to the kin of the deceased with cremation an accepted method of disposition of the body.
Ministers
Klassen strove for every member to engage in recruitment and as such, granted "Ministerial Certificates" to "any legitimate White Man or Woman over the age of 16" who convinced church leadership that they were "dedicated to the noble cause of the White Race". Prospective ministers must demonstrate worthiness and pass written and oral examinations. The written exams consist of 150 questions (requiring a one-paragraph response to each) and an essay. Applicants are encouraged to request recommendations from three established ministers, and the final requirement is the signing of an oath.
Books
The two main texts behind Creativity are Nature's Eternal Religion and The White Man's Bible, written by Klassen in 1973. The books teach that the white race is the "pinnacle of Nature's creation", "nature's finest" and outlined a foundation for a "white racial religion". Section one of the first book critiques Christianity, black people as a "plague" and Jewish people as "parasitical masters of deceit". Many biblical stories, including those of Adam and Eve, Jonah and the whale and the resurrection of Jesus, are critiqued extensively in successive books penned by Klassen. The historicity of Jesus is denied, with Klassen affirming his belief in the Christ myth theory, a fringe ideology which claims that Jesus, the founder and central figure of Christianity was not a historical figure but was instead a fictional character. According to Creativity, Christianity is a violent religion which has killed 1,000 fellow Christians for every Christian killed by the Romans.
Adherents reject Christian teachings such as the Sermon on the Mount and Christian pacifism as leading to "racial suicide" and Christianity as having been formulated by Jews to destroy the Roman Empire with Islam being a "militant religion" having been formed as a Jewish plot to "mobilize the mud races" to invade and conquer Europe. They reject the exhortation in the Bible's Matthew 5:44 to "love one's enemies", believing that enemies should be hated, if not destroyed. In section two of the first text, Klassen went about laying the foundation for a "racial religion" to "replace Christ-Insanity" (as he referred to Christianity). In it, members are to reject the Golden Rule, saying that it does not make "good sense" and at a "closer look" it is a "completely unworkable principle" replacing it with its own "Golden Rule": What is good for the white race is the highest virtue and what is bad for the white race is the ultimate sin; racial loyalty is the greatest of all honors and racial treason is the worst of all crimes.
Klassen published an additional 11 books including Expanding Creativity, Building a Whiter and Brighter World and Rahowa! This Planet Is All Ours.
Figures
Gaede family
April Harrington (Gaede), mother of Lynx and Lamb Lingelser (Gaede) of the band Prussian Blue, was a longtime supporter of Creativity and a member of the World Church of the Creator, naming her third daughter Dresden Hale after its leader Matthew F. Hale before joining the National Alliance and then the splinter National Vanguard. Prussian Blue's song "Stand Up", written for David Lane (author of the Fourteen Words), was part of the unreleased Free Matt Hale CD intended to support the incarcerated Hale. Lamb and Lynx Gaede have denounced the movement, saying that they never chose it and were controlled by their mother.
Craig Cobb
Craig Cobb, who operated the video-sharing website Podblanc, has attempted to take over small towns in the Midwestern United States. He tried to establish an enclave in North Dakota and rename it "Trump Creativity" or "Creativity Trump" for Donald Trump. A church building purchased by Cobb to establish an enclave was "burned to the ground" in Nome, North Dakota.
George Burdi
George Burdi, also known as George Eric Hawthorne, was lead singer of the Canadian metal band RaHoWa, leader of the Toronto branch of the Church of the Creator, and founder of Resistance Records. He was convicted of assault, and claimed he renounced racism after serving time in prison. Burdi has been credited with a role in Creativity's survival after the death of Ben Klassen. In 2017, Burdi returned to the White nationalist scene, though not to the Creativity religion itself.
Matthew F. Hale
Several years after Klassen's 1993 death, white supremacist Matthew Hale founded the New Church of the Creator (later the World Church of the Creator). Hale made national news when he was denied admission to the Illinois State Bar on three occasions due to his racist beliefs. On November 12, 1999, the Illinois Supreme Court refused to further consider the denial of Hale's law license, continuing "a decision by its Committee on Character and Fitness that said Hale lacked the moral character to practice law." According to Hale, the committee's denial of his law license may have provoked Benjamin Nathaniel Smith's drive-by shooting spree.
On January 9, 2003, Hale was arrested and charged with attempting to direct security chief Anthony Evola to murder judge Joan Lefkow. Hale was found guilty of four of five counts (one count of solicitation of murder and three counts of obstruction of justice) on April 26, 2004; in April 2005, he was sentenced to 40 years in a Federal penitentiary.
Johannes Grobbelaar and Jurgen White
Johannes Grobbelaar and Jurgen White, Afrikaner Creators and members of the National Socialist Partisans (the paramilitary branch of the Blanke Bevrydingsbeweging), were killed in a November 1991 gun battle with South African police near Upington while attempting to smuggle weapons and explosives into a survivalist compound in Namibia. They were stopped by police, who were suspicious that their vehicle had been stolen. According to the report, while being escorted to a nearby police station they detonated a smoke bomb and attempted to escape. Police discovered their abandoned vehicle five miles away; Grobbelaar and White ambushed them. Two officers were shot, one fatally.
Ron McVan
Ron McVan, co-founder of the Wotansvolk racialist pagan group, was once affiliated with the Church of the Creator for two years as its second-in-command; McVan contributed articles and artwork to its periodical, Racial Loyalty, and was a martial-arts instructor for the church. Although Klassen and McVan shared anti-Christian beliefs, McVan sought a more spiritual approach and felt that Creativity needed spirituality. He moved to the Pacific Northwest and founded Wotan's Kindred in Portland, Oregon in 1992, saying that the group was rooted in the "genetic character and collective identity" of the white race.
David Lane, McVan's associate and co-founder of Wotansvolk, drew inspiration from Creativity, particularly ideas of a "racial religion", but did not agree with Creativity's "atheistic" stance and considered himself deist.
William Christopher Gibbs
William Christopher Gibbs, a Church of Creativity adherent in Georgia and a member of the Creativity Alliance, was arrested for possession of the biological toxin ricin. Gibbs went to a hospital after he accidentally got the ricin on his hands while experimenting with it.
On September 21, 2018, a Federal judge ordered Gibbs' release from Federal custody because of a technicality: ricin had been inexplicably dropped from the list of illegal biological toxins which are known as "select agents" due to changes in the 2004 law and edits to regulations in 2005. The judge did not rule out the possibility that Gibbs could be potentially convicted under another Federal law. Gibbs continued to be incarcerated in the Fannin County, Georgia jail under a misdemeanor charge of reckless conduct which stemmed from his 2017 arrest and a probation violation connected to a 2010 conviction for burglary.
Legal problems and reorganization
In 1992, faced with financial and legal problems (including a civil lawsuit filed by the Southern Poverty Law Center) and the death of his wife, the aging Klassen looked for a successor. Although Rudolph G. ("Butch") Stanko was favored for the position, he was imprisoned at the time. Klassen selected Charles Edward Altvater, but replaced him before he could assume leadership (possibly due to recurrent criminal charges); then chose Milwaukee neo-Nazi Mark Wilson, who ran the church from July 1992 to January 1993. Klassen abruptly replaced Wilson with Richard McCarty, working to establish McCarty in the Creativity community, before selling most of the church's property to the National Alliance's William Luther Pierce for $100,000. Pierce quickly sold the property to an unaffiliated third party for $185,000.
Shortly before and during McCarty's leadership, Creativity was plagued with legal problems; members were arrested for conspiracy, unlawful firearms possession and their association with the July 1993 firebombing of an NAACP building in Tacoma, Washington. McCarty struggled to keep the group unified. The lawsuit filed by the Southern Poverty Law Center (SPLC), seeking damages related to the May 1991 murder of Harold Mansfield, Jr. by Creator George Loeb, finally led to a March 1994 court ruling which fined the Church of the Creator $1,000,000. The court also ruled that Klassen's property sale to Pierce shortly before his suicide was collusion to deny payment to Mansfield's family, ordering Pierce to return his $85,000 profit from the resale of the property. With the church unable to pay the outstanding balance, the SPLC sued for its dissolution to settle the remaining damages and McCarty readily agreed.
Creativity Movement
Matthew F. Hale founded the New Church of the Creator in 1996, later renamed the World Church of the Creator. Hale's World Church of the Creator was a new and separate group rather than a direct successor to Ben Klassen's Church of the Creator. Until his arrest in 2003, Hale was the only Pontifex Maximus of the now-defunct World Church of the Creator. The current group known as The Creativity Movement is a white power skinhead-oriented direct successor to Hale's World Church of the Creator.
Headquartered in Zion, Illinois, with a heavy concentration of Creators in Montana, and 24 regional branches, it also claims to have local branches and members "all over the world".
In 2000 the Oregon-based TE-TA-MA Truth Foundation filed a lawsuit against the World Church of the Creator for using the name "Church of the Creator", since the Oregon group had trademarked and registered the name in 1982. U.S. District Court Judge Joan Lefkow ruled for the World Church of the Creator. In December 2002, the World Church of the Creator was fined $1,000 for each day it continued using the old name. Further appeals were denied by the U.S. Supreme Court in 2003. Hale was charged with contempt of court and soliciting the murder of judge Joan Lefkow, and sentenced to 40 years' imprisonment on April 6, 2005. Bill White was convicted of threatening a juror in the Matthew Hale case and sentenced to 42 months in prison.
In early 2017, a group which referred to itself as the "Guardians of the Faith Committee" of the Creativity Movement elected James Costello of England as its "Pontifex Maximus".
Costello was convicted of inciting racial hatred in November 2023, and he was sentenced to serve a 5 year prison term.
Creativity Alliance
Australian man Cailen Cambeul, formerly known as Colin Campbell, was the co-founder of the Creativity Alliance in 2003.
In 2017 Joseph Esposito was appointed the Pontifex Maximus (Elect) of the Creativity Alliance (Church of Creativity Oregon). For a short period of time, the Creativity Alliance was known as the White Crusaders of the Rahowa (WCOTR), which was founded by former World Church of the Creator Members after Hale's arrest in 2003. Esposito in Oregon (but formerly of Florida), and another former Klassen supporter, George Loeb in Florida, are each serving extended prison sentences.
According to a Southern Poverty Law Center report, in 2015, the Creativity Alliance had groups in Georgia, Pennsylvania, South Carolina, Utah and Vermont. Creativity Alliance web pages and published books stress that they make no attempt to assume or supersede the registered trademark "Church of the Creator", owned by the TE-TA-MA Truth Foundation.
Randolph Dilloway, former Hasta Primus (Secretary, or second in command) of the Creativity Alliance and founder of the defunct Smoky Mountains Church of Creativity, was an accountant for the revived National Alliance (an unaffiliated neo-Nazi group which was formerly led by William Luther Pierce, the author of The Turner Diaries) who assessed the financial damage which was done to that organization by its past leadership. Claiming to fear for his life after he discovered (and discussed) the errors, Dilloway contacted police and the SPLC and he also furnished them with documents in which he alleged that members of the National Alliance committed fraud and embezzlement.
In 2017, the Creativity Alliance was found to be responsible for the distribution of flyers throughout Pittsburgh, Pennsylvania.
US members who have been arrested include a man from the Church of Creativity Georgia who was arrested for attempting to make ricin poison (the charge was later dropped), and Hardy Lloyd, a member from Pennsylvania, was arrested for violating his probation by distributing racist flyers, hoarding weapons, and participating in white supremacist web forums.
Australia
Cailen Cambeul co-founded the Creativity Alliance in 2003, several years after he joined the World Church of the Creator, and he served as the Creativity Alliance's first "Pontifex Maximus" (meaning "highest priest") from 2009 until 2016. He has led the Creativity Alliance in one capacity or another since 2003, and has stated that he intends to hand over leadership of the group when Pontifex Maximus (Elect) Joseph Esposito is free to take control. He was the fifth overall Pontifex Maximus of Creativity as a religion (B. Klassen, M. Wilson, R. McCarty, M. Hale, C. Cambeul) he was also the first leader of Creativity who was resident outside the United States. His current position and title is Church Administrator. His chapter of the group is named the Church of Creativity South Australia. Born in Adelaide, South Australia, Campbell describes himself as a "former outlaw biker and a former soldier in the Australian Army." He claims that he had a daughter who was "kidnapped" by the state, and he sees the church as an outlet for his "natural aggression".
Creativity Alliance members are known to regularly distribute flyers; particularly in Australia and New Zealand.
The Attorney-General of South Australia and the Minister for Multicultural Affairs have made a number of attempts to close the website of the South Australian representative and Pontifex Maximus of the Creativity Alliance and outlaw the organization. Cambeul filed a complaint with the Australian Press Council that describing the Creativity Alliance as a white-supremacist organization (rather than a religion) and characterizing its members as "a few loners looking for something to do with all their hate" was unfair. His complaint was dismissed on the basis that the journalist's assessment was not a news article but an opinion piece.
United Kingdom
In 2015, the CA distributed flyers in Inverbervie (Scotland) and Liverpool. A reverend speaking on behalf of the Church of Creativity Britain said in a letter to the editor that the leaflets were legal and called for racial separation, not supremacy.
Other legal cases
Creativity was recognized as a religion by the United States District Court for the Eastern District of Wisconsin in Peterson v. Wilmur Communications (205 F.Supp.2d 1014) (2002). The American Civil Liberties Union intervened on behalf of the World Church of the Creator.
California federal judge Maxine M. Chesney ruled against an imprisoned Creator who brought a suit against Pelican Bay State Prison based on an alleged violation of the Religious Land Use and Institutionalized Persons Act in Conner v. Tilton, 2009 U.S. Dist. LEXIS 111892 (ND CA, Dec. 2, 2009), in which Creativity and several other organizations and belief systems (including MOVE, veganism and the Church of Marijuana) were declared to not constitute "religions" but moral or secular philosophies under the definition of religion based on addressing of "fundamental and ultimate questions having to do with deep and imponderable matters" as part of a three-point test for determining religion developed by the United States Court of Appeals for the Third Circuit. The court concluded that the plaintiff had failed to raise a genuine issue about whether Creativity is a religion; it found that to the extent Creativity deals with a "fundamental concern", the concern is with secular matters and not with what the court considered to be religious principles. Creativity is not "comprehensive" in nature because it was presented as confined to one question (or moral teaching), and that the structural characteristics of Creativity "do not serve to transform what are otherwise secular teachings and ideals into a religious ideology." In Hale v. Federal Bureau of Prisons (2015), the court found that Creativity may qualify as a religion under the First Amendment to the United States Constitution (with potential tax exemption by the IRS) and may be practiced in prison.
Furthermore, on March 12, 1989, U.S. federal judge Fern M. Smith of the United States District Court for the Northern District of California ordered San Quentin prison authorities to return "The White Man's Bible" to an inmate after it was confiscated and the state failed to prove that the book presented an imminent danger.
Leafletting campaigns
In March 2015, leaflets which contained the slogan: "The white race is nature’s finest" were posted on doors in southern Liverpool, in the United Kingdom. Cailen Cambeul, Creativity minister and then the Pontifex Maximus of the Creativity Alliance, stated that he was responsible for the distribution of the leaflets. Complaints were lodged to the police by local councilors. Sarah Jennings of the local Green Party denounced Creativity as a "fringe group of blatant racists". According to Cambeul, "Any politician claiming disgust at our flyers and seeking to make political gains via our 100-percent-legal message is partaking in an opportunistic abuse of power at the expense of innocent people exercising their rights to speak out against the injustices of a politically correct world."
In the United States, northwest Montana, particularly the Flathead Valley, has seen the distribution of a "flurry of racist fliers" which promote the Creativity movement. The Southern Poverty Law Center listed Creativity Alliance presence in the state in 2015.
See also
Far-right subcultures
List of fascist movements
List of neo-Nazi organizations
List of white nationalist organizations
Nontheistic religion
Radical right (Europe)
Radical right (United States)
References
External links
Official website of the Creativity Alliance
Nature's Eternal Religion by Ben Klassen, 1973.
Portfolio One – First 20 issues of the religion's flagship magazine Racial Loyalty.
1973 establishments in Florida
Anti-Christian sentiment in the United States
Antitheism
Atheism in the United States
Atheist organizations
Neo-Nazi concepts
Neo-Nazi organizations in the United States
New religious movements
Organizations based in Illinois
Religion and race
Religions that require veganism
Religious atheism
Religious belief systems founded in the United States
Religious organizations established in 1973
Scientific racism
White separatism | Creativity (religion) | Biology | 7,383 |
443,061 | https://en.wikipedia.org/wiki/Mung%20%28computer%20term%29 | Mung or munge is computer jargon for a series of potentially destructive or irrevocable changes to a piece of data or a file. It is sometimes used for vague data transformation steps that are not yet clear to the speaker. Common munging operations include removing punctuation or HTML tags, data parsing, filtering, and transformation.
The term was coined in 1958 in the Tech Model Railroad Club at the Massachusetts Institute of Technology. In 1960 the backronym "Mash Until No Good" was created to describe Mung, and by 1976 it was revised to "Mung Until No Good", making it one of the first recursive acronyms. It lived on as a recursive command in the editing language TECO.
Munging may also describe the constructive operation of tying together systems and interfaces that were not specifically designed to interoperate (also called 'duct-taping'). Munging can also describe the processing or filtering of raw data into another form.
As the "no good" part of the acronym implies, munging often involves irrevocable destruction of data.
See also
Jargon File – a glossary of hacker slang.
Slug – an application of munging for creating human-friendly URLs.
Kludge – a neologism developed near this time with a similar meaning
Munged password (referring to a slightly different process)
Data wrangling
References
External links
Jargon File entry
Mung and munge at FOLDOC
Email address munging is considered harmful
Computer jargon
Computer data
1950s neologisms | Mung (computer term) | Technology | 318 |
1,190,887 | https://en.wikipedia.org/wiki/Pilot%20wave%20theory | In theoretical physics, the pilot wave theory, also known as Bohmian mechanics, was the first known example of a hidden-variable theory, presented by Louis de Broglie in 1927. Its more modern version, the de Broglie–Bohm theory, interprets quantum mechanics as a deterministic theory, and avoids issues such as wave function collapse, and the paradox of Schrödinger's cat by being inherently nonlocal.
The de Broglie–Bohm pilot wave theory is one of several interpretations of (non-relativistic) quantum mechanics.
History
Louis de Broglie's early results on the pilot wave theory were presented in his thesis (1924) in the context of atomic orbitals where the waves are stationary. Early attempts to develop a general formulation for the dynamics of these guiding waves in terms of a relativistic wave equation were unsuccessful until in 1926 Schrödinger developed his non-relativistic wave equation. He further suggested that since the equation described waves in configuration space, the particle model should be abandoned. Shortly thereafter, Max Born suggested that the wave function of Schrödinger's wave equation represents the probability density of finding a particle. Following these results, de Broglie developed the dynamical equations for his pilot wave theory. Initially, de Broglie proposed a double solution approach, in which the quantum object consists of a physical wave (u-wave) in real space which has a spherical singular region that gives rise to particle-like behaviour; in this initial form of his theory he did not have to postulate the existence of a quantum particle. He later formulated it as a theory in which a particle is accompanied by a pilot wave.
De Broglie presented the pilot wave theory at the 1927 Solvay Conference. However, Wolfgang Pauli raised an objection to it at the conference, saying that it did not deal properly with the case of inelastic scattering. De Broglie was not able to find a response to this objection, and he abandoned the pilot-wave approach. Unlike David Bohm years later, de Broglie did not complete his theory to encompass the many-particle case. The many-particle case shows mathematically that the energy dissipation in inelastic scattering could be distributed to the surrounding field structure by a yet-unknown mechanism of the theory of hidden variables.
In 1932, John von Neumann published a book, part of which claimed to prove that all hidden variable theories were impossible. This result was found to be flawed by Grete Hermann three years later, though for a variety of reasons this went unnoticed by the physics community for over fifty years.
In 1952, David Bohm, dissatisfied with the prevailing orthodoxy, rediscovered de Broglie's pilot wave theory. Bohm developed pilot wave theory into what is now called the de Broglie–Bohm theory. The de Broglie–Bohm theory itself might have gone unnoticed by most physicists, if it had not been championed by John Bell, who also countered the objections to it. In 1987, John Bell rediscovered Grete Hermann's work, and thus showed the physics community that Pauli's and von Neumann's objections only showed that the pilot wave theory did not have locality.
The pilot wave theory
Principles
The pilot wave theory is a hidden-variable theory. Consequently:
the theory has realism (meaning that its concepts exist independently of the observer);
the theory has determinism.
The positions of the particles are considered to be the hidden variables. The observer doesn't know the precise values of these variables; they cannot know them precisely because any measurement disturbs them. On the other hand, the observer is defined not by the wave function of their own atoms but by the atoms' positions. So what one sees around oneself are also the positions of nearby things, not their wave functions.
A collection of particles has an associated matter wave which evolves according to the Schrödinger equation. Each particle follows a deterministic trajectory, which is guided by the wave function; collectively, the density of the particles conforms to the magnitude of the wave function. The wave function is not influenced by the particle and can exist also as an empty wave function.
The theory brings to light nonlocality that is implicit in the non-relativistic formulation of quantum mechanics and uses it to satisfy Bell's theorem. These nonlocal effects can be shown to be compatible with the no-communication theorem, which prevents use of them for faster-than-light communication, and so is empirically compatible with relativity.
Macroscopic analog
Couder, Fort, et al. claimed that macroscopic oil droplets on a vibrating fluid bath can be used as an analogue model of pilot waves; a localized droplet creates a periodical wave field around itself. They proposed that resonant interaction between the droplet and its own wave field exhibits behaviour analogous to quantum particles: interference in double-slit experiment, unpredictable tunneling (depending in a complicated way on a practically hidden state of field), orbit quantization (that a particle has to 'find a resonance' with field perturbations it creates—after one orbit, its internal phase has to return to the initial state) and Zeeman effect. Attempts to reproduce these experiments have shown that wall-droplet interactions rather than diffraction or interference of the pilot wave may be responsible for the observed hydrodynamic patterns, which are different from slit-induced interference patterns exhibited by quantum particles.
Mathematical foundations
To derive the de Broglie–Bohm pilot-wave for an electron, the quantum Lagrangian
where is the potential energy, is the velocity and is the potential associated with the quantum force (the particle being pushed by the wave function), is integrated along precisely one path (the one the electron actually follows). This leads to the following formula for the Bohm propagator:
This propagator allows one to precisely track the electron over time under the influence of the quantum potential .
Derivation of the Schrödinger equation
Pilot wave theory is based on Hamilton–Jacobi dynamics, rather than Lagrangian or Hamiltonian dynamics. Using the Hamilton–Jacobi equation
it is possible to derive the Schrödinger equation:
Consider a classical particle – the position of which is not known with certainty. We must deal with it statistically, so only the probability density is known. Probability must be conserved, i.e. for each . Therefore, it must satisfy the continuity equation
where is the velocity of the particle.
In the Hamilton–Jacobi formulation of classical mechanics, velocity is given by where is a solution of the Hamilton-Jacobi equation
and can be combined into a single complex equation by introducing the complex function then the two equations are equivalent to
with
The time-dependent Schrödinger equation is obtained if we start with the usual potential with an extra quantum potential . The quantum potential is the potential of the quantum force, which is proportional (in approximation) to the curvature of the amplitude of the wave function.
Note this potential is the same one that appears in the Madelung equations, a classical analog of the Schrödinger equation.
Mathematical formulation for a single particle
The matter wave of de Broglie is described by the time-dependent Schrödinger equation:
The complex wave function can be represented as:
By plugging this into the Schrödinger equation, one can derive two new equations for the real variables. The first is the continuity equation for the probability density
where the velocity field is determined by the “guidance equation”
According to pilot wave theory, the point particle and the matter wave are both real and distinct physical entities (unlike standard quantum mechanics, which postulates no physical particle or wave entities, only observed wave-particle duality).
The pilot wave guides the motion of the point particles as described by the guidance equation.
Ordinary quantum mechanics and pilot wave theory are based on the same partial differential equation. The main difference is that in ordinary quantum mechanics, the Schrödinger equation is connected to reality by the Born postulate, which states that the probability density of the particle's position is given by Pilot wave theory considers the guidance equation to be the fundamental law, and sees the Born rule as a derived concept.
The second equation is a modified Hamilton–Jacobi equation for the action :
where is the quantum potential defined by
If we choose to neglect , our equation is reduced to the Hamilton–Jacobi equation of a classical point particle. So, the quantum potential is responsible for all the mysterious effects of quantum mechanics.
One can also combine the modified Hamilton–Jacobi equation with the guidance equation to derive a quasi-Newtonian equation of motion
where the hydrodynamic time derivative is defined as
Mathematical formulation for multiple particles
The Schrödinger equation for the many-body wave function is given by
The complex wave function can be represented as:
The pilot wave guides the motion of the particles. The guidance equation for the jth particle is:
The velocity of the jth particle explicitly depends on the positions of the other particles.
This means that the theory is nonlocal.
Relativity
An extension to the relativistic case with spin has been developed since the 1990s.
Empty wave function
Lucien Hardy and John Stewart Bell have emphasized that in the de Broglie–Bohm picture of quantum mechanics there can exist empty waves, represented by wave functions propagating in space and time but not carrying energy or momentum, and not associated with a particle. The same concept was called ghost waves (or "Gespensterfelder", ghost fields) by Albert Einstein. The empty wave function notion has been discussed controversially. In contrast, the many-worlds interpretation of quantum mechanics does not call for empty wave functions.
See also
Hydrodynamic quantum analogues
Quantum potential
Notes
References
External links
"Pilot waves, Bohmian metaphysics, and the foundations of quantum mechanics" , lecture course on pilot wave theory by Mike Towler, Cambridge University (2009).
Klaus von Bloh's Bohmian mechanics demonstrations in: Wolfram Demonstrations Project
Hidden variable theory
Interpretations of quantum mechanics
Quantum measurement | Pilot wave theory | Physics | 2,072 |
37,187,938 | https://en.wikipedia.org/wiki/Irrationality%20sequence | In mathematics, a sequence of positive integers an is called an irrationality sequence if it has the property that for every sequence xn of positive integers, the sum of the series
exists (that is, it converges) and is an irrational number. The problem of characterizing irrationality sequences was posed by Paul Erdős and Ernst G. Straus, who originally called the property of being an irrationality sequence "Property P".
Examples
The powers of two whose exponents are powers of two, , form an irrationality sequence. However, although Sylvester's sequence
2, 3, 7, 43, 1807, 3263443, ...
(in which each term is one more than the product of all previous terms) also grows doubly exponentially, it does not form an irrationality sequence. For, letting for all gives
a series converging to a rational number. Likewise, the factorials, , do not form an irrationality sequence because the sequence given by for all leads to a series with a rational sum,
Growth rate
For any sequence an to be an irrationality sequence, it must grow at a rate such that
.
This includes sequences that grow at a more than doubly exponential rate as well as some doubly exponential sequences that grow more quickly than the powers of powers of two.
Every irrationality sequence must grow quickly enough that
However, it is not known whether there exists such a sequence in which the greatest common divisor of each pair of terms is 1 (unlike the powers of powers of two) and for which
Related properties
Analogously to irrationality sequences,
has defined a transcendental sequence to be an integer sequence an such that, for every sequence xn of positive integers, the sum of the series
exists and is a transcendental number.
References
Integer sequences
Irrational numbers
Number theory | Irrationality sequence | Mathematics | 373 |
49,516,160 | https://en.wikipedia.org/wiki/Sticky%3A%20A%20%28Self%29%20Love%20Story | Sticky: A (Self) Love Story is a 2016 documentary and comedy film by Nicholas Tana that attempts to explain why most people are afraid to discuss masturbation. The movie is one of the first documentaries to address the myths and social taboos around masturbation. The trailer for Sticky: A (Self) Love Story was selected as top trailers of the week by IndieWire.
Impact on sex education
The feature-length documentary has received positive reviews in national media for its controversial stance in favor of masturbation as part of sex education. The filmmaker Nicholas Tana was paid to speak during a screening of his film at the 47th. annual American Association of Sex Educators, Counselors, and Therapists (A.A.S.E.C.T.) conference in Minneapolis in 2015 during which time an early educational cut of the film was screened in front of over a hundred certified sex educators.
The A.A.S.E.C.T. screening resulted in invitations to conduct educational screenings at Arizona State University sponsored by VOX Voices For Planned Parenthood, University of Wisconsin sponsored by Sex Outloud, and Eastern Michigan University spearheaded by Pam Landau of the Psychology department in April 2016 and ending in May 2016 in honor of international Masturbation Month.
The film addresses the need for sex education that discusses masturbation in a healthy manner to students; it includes interviews with sex educators who express concerns about not properly educating children around sex and masturbation. Harvard University screened Sticky: A (Self) Love Story on campus in Cambridge, Massachusetts, on April 4, 2017, as part of Harvard's Sex Weekend.
Contrasting viewpoints on health
Full of interviews from sex educators, religious figures, and psychologists, the documentary offers often contrasting opinions about the health benefits both physically and psychologically of masturbation. Among those interviewed who believe masturbation could be harmful is Alexander Rhodes, the founder of a popular Reddit masturbation abstinence group called NoFap. The movie also includes health findings associated with a Cambridge Study that link masturbation to prostate cancer.
These perspectives are contrasted with sex-positive statements from notable sex educators who speak in favor of the health benefits of masturbation. The film also references a medical study written in JAMA indicating that masturbation might help to prevent prostate cancer.
Sex-positive feminism
The film contains interviews with some of the founding members of the sex-positive feminism movement. These interviewees include Nina Hartley, Betty Dodson, Joani Blank, and Carol Queen. Judy Norsidian and Wendy Sanford who worked for many years on the publication of the historical sex education book Our Bodies, Ourselves both appear in the film.
Issues
Among the issues discussed in the film is the Anti-Obscenity Act that bans the sale of sex toys in the state of Alabama, and the contradictory stances of four major religions surrounding masturbation, which include Catholicism, Islam, Buddhism, and Judaism.
Other topics include the controversial firing of the first African American Surgeon General by former U.S. President Bill Clinton; the career damaging fall-out after Paul Reubens's (Pee-Wee Herman) arrest for being caught in a pornographic theatre; current debates concerning sex education; the billion dollar sex toy industry; contradictory prostate cancer studies linked to male masturbation; the news media's obsession with sex addiction and sexual compulsion; the F.B.I. study that links compulsive masturbation to serial killers; the impact of pornography on relationships; opinions as to the future of masturbation.
Masturbation in politics
The film contains an interview with the first African American appointed as Surgeon General, Joycelyn Elders, about why she was fired by former president Bill Clinton for her controversial statement on world's A.I.D.S. day in favor of sex education on masturbation, an interview with comedian Janeane Garofalo about her embarrassment on doing the phone sex masturbation scene in The Truth About Cats & Dogs, and an interview with Hustler creator Larry Flynt about how he came to discover masturbation.
Masturbation in film, TV, and music
The impact of masturbation on the media is explored through a series of movie clips and music. Film Threat founder and film critic Chris Gore states in the documentary that most instances of masturbation depicted in movies or television are seen as either grotesque or as something one wouldn't want to be caught doing. This comment is substantiated by clips from movies like The Exorcist and American Pie shown in the film.
Television clips from the Seinfeld episode called "The Contest" and a clip from Sex in the City are also discussed, along with songs that make reference to masturbation in some way. A section in the film on Masturbation and Media includes interviews with comedian ANT, and Keith Morris, singer/songwriter formerly of Black Flag and The Circle Jerks. The movie features an acoustic performance of "I Touch Myself" played by its songwriter, Billy Steinberg, who is also interviewed.
V.O.D. distribution
First distributed in time for Valentine's Day in February 2016 by Vision Films Inc., a partner of Sony Pictures Home Entertainment in February 2016, Sticky: A (Self) Love Story has been selected as an Amazon Video Direct Stars (A.V.D.) winner in July 2016 after being one of Amazon's top-selling films online. At the time of this article, the documentary is being distributed in the U.S., Canada, U.K., Italy, Israel, Brazil, and Germany.
Theatrical screenings
There have been numerous theatrical screenings of Sticky: A (Self) Love Story around the world. These include screenings in New York, Las Vegas, Los Angeles, San Francisco, and San Diego and sold out screenings at MoSex in New York, Syndicated in Brooklyn, and the historic Chinese Theater in Hollywood, California. Sticky: A (Self) Love Story opened at the first annual Lov Doc Film Festival in Moscow, Russia, in 2016.
References
External links
Amazon
2016 documentary films
2016 films
Sexuality
Habits
Masturbation
Sexology literature
Sex positivism
Documentary films about sexuality
2010s English-language films
English-language documentary films | Sticky: A (Self) Love Story | Biology | 1,273 |
71,696,261 | https://en.wikipedia.org/wiki/HD%2030432 | HD 30432, also known as HR 1526, is a solitary, orange hued star located in the southern constellation of Caelum, the chisel. It has an apparent magnitude of 6.04, making it faintly visible to the naked eye if viewed under ideal conditions. Based on parallax measurements from the Gaia spacecraft, the object is estimated to be 310 light years distant. It appears to be approaching the Solar System, having a fairly constrained radial velocity of . Eggen (1993) lists it as a member of the old disk population.
HD 30432 has a stellar classification of K1 III, indicating that it is an evolved giant star. It is currently on the red giant branch, fusing a hydrogen shell around an inert helium core. It has 2.8 times the mass of the Sun and is estimated to be 455 million years old. At that age, the star has expanded to 9.5 times the radius of the Sun and now has a cool effective temperature of . Despite the low temperature, HD 30432 shines with a luminosity 39 times that of the Sun from its photosphere. It has a metallicity 16% below solar levels, making it slightly metal deficient. Like most giants, HR 1526 spins slowly, with its projected rotational velocity being lower than .
References
K-type giants
Caelum
Caeli, 15
030432
022144
1526
CD-39 01624 | HD 30432 | Astronomy | 297 |
52,431,411 | https://en.wikipedia.org/wiki/NGC%20373 | NGC 373 is an elliptical galaxy located around 204 million light-years away in the constellation Pisces. NGC 373 was discovered on December 12th, 1876 by John Louis Emil Dreyer. NGC 373 does not contain an active galactic nucleus, and it does not have much star formation.
References
External links
0373
18761212
Pisces (constellation)
Elliptical galaxies
003946 | NGC 373 | Astronomy | 81 |
513,506 | https://en.wikipedia.org/wiki/Krohn%E2%80%93Rhodes%20theory | In mathematics and computer science, the Krohn–Rhodes theory (or algebraic automata theory) is an approach to the study of finite semigroups and automata that seeks to decompose them in terms of elementary components. These components correspond to finite aperiodic semigroups and finite simple groups that are combined in a feedback-free manner (called a "wreath product" or "cascade").
Krohn and Rhodes found a general decomposition for finite automata. The authors discovered and proved an unexpected major result in finite semigroup theory, revealing a deep connection between finite automata and semigroups.
Definitions and description of the Krohn–Rhodes theorem
Let T be a semigroup. A semigroup S that is a homomorphic image of a subsemigroup of T is said to be a divisor of T.
The Krohn–Rhodes theorem for finite semigroups states that every finite semigroup S is a divisor of a finite alternating wreath product of finite simple groups, each a divisor of S, and finite aperiodic semigroups (which contain no nontrivial subgroups).
In the automata formulation, the Krohn–Rhodes theorem for finite automata states that given a finite automaton A with states Q and input set I, output alphabet U, then one can expand the states to Q' such that the new automaton A' embeds into a cascade of "simple", irreducible automata: In particular, A is emulated by a feed-forward cascade of (1) automata whose transformation semigroups are finite simple groups and (2) automata that are banks of flip-flops running in parallel. The new automaton A' has the same input and output symbols as A. Here, both the states and inputs of the cascaded automata have a very special hierarchical coordinate form.
Moreover, each simple group (prime) or non-group irreducible semigroup (subsemigroup of the flip-flop monoid) that divides the transformation semigroup of A must divide the transformation semigroup of some component of the cascade, and only the primes that must occur as divisors of the components are those that divide A's transformation semigroup.
Group complexity
The Krohn–Rhodes complexity (also called group complexity or just complexity) of a finite semigroup S is the least number of groups in a wreath product of finite groups and finite aperiodic semigroups of which S is a divisor.
All finite aperiodic semigroups have complexity 0, while non-trivial finite groups have complexity 1. In fact, there are semigroups of every non-negative integer complexity. For example, for any n greater than 1, the multiplicative semigroup of all (n+1) × (n+1) upper-triangular matrices over any fixed finite field has complexity n (Kambites, 2007).
A major open problem in finite semigroup theory is the decidability of complexity: is there an algorithm that will compute the Krohn–Rhodes complexity of a finite semigroup, given its multiplication table?
Upper bounds and ever more precise lower bounds on complexity have been obtained (see, e.g. Rhodes & Steinberg, 2009). Rhodes has conjectured that the problem is decidable.
History and applications
At a conference in 1962, Kenneth Krohn and John Rhodes announced a method for decomposing a (deterministic) finite automaton into "simple" components that are themselves finite automata. This joint work, which has implications for philosophy, comprised both Krohn's doctoral thesis at Harvard University and Rhodes' doctoral thesis at MIT.<ref>Morris W. Hirsch, "Foreword to Rhodes' Applications of Automata Theory and Algebra". In J. Rhodes, Applications of Automata Theory and Algebra: Via the Mathematical Theory of Complexity to Biology, Physics, Philosophy and Games", (ed. C. L. Nehaniv), World Scientific Publishing Co., 2010.</ref> Simpler proofs, and generalizations of the theorem to infinite structures, have been published since then (see Chapter 4 of Rhodes and Steinberg's 2009 book The q-Theory of Finite Semigroups for an overview).
In the 1965 paper by Krohn and Rhodes, the proof of the theorem on the decomposition of finite automata (or, equivalently sequential machines) made extensive use of the algebraic semigroup structure. Later proofs contained major simplifications using finite wreath products of finite transformation semigroups. The theorem generalizes the Jordan–Hölder decomposition for finite groups (in which the primes are the finite simple groups), to all finite transformation semigroups (for which the primes are again the finite simple groups plus all subsemigroups of the "flip-flop" (see above)). Both the group and more general finite automata decomposition require expanding the state-set of the general, but allow for the same number of input symbols. In the general case, these are embedded in a larger structure with a hierarchical "coordinate system".
One must be careful in understanding the notion of "prime" as Krohn and Rhodes explicitly refer to their theorem as a "prime decomposition theorem" for automata. The components in the decomposition, however, are not prime automata (with prime defined in a naïve way); rather, the notion of prime is more sophisticated and algebraic: the semigroups and groups associated to the constituent automata of the decomposition are prime (or irreducible) in a strict and natural algebraic sense with respect to the wreath product (Eilenberg, 1976). Also, unlike earlier decomposition theorems, the Krohn–Rhodes decompositions usually require expansion of the state-set, so that the expanded automaton covers (emulates) the one being decomposed. These facts have made the theorem difficult to understand and challenging to apply in a practical way—until recently, when computational implementations became available (Egri-Nagy & Nehaniv 2005, 2008).
H.P. Zeiger (1967) proved an important variant called the holonomy decomposition (Eilenberg 1976). The holonomy method appears to be relatively efficient and has been implemented computationally by A. Egri-Nagy (Egri-Nagy & Nehaniv 2005).
Meyer and Thompson (1969) give a version of Krohn–Rhodes decomposition for finite automata that is equivalent to the decomposition previously developed by Hartmanis and Stearns, but for useful decompositions, the notion of expanding the state-set of the original automaton is essential (for the non-permutation automata case).
Many proofs and constructions now exist of Krohn–Rhodes decompositions (e.g., [Krohn, Rhodes & Tilson 1968], [Ésik 2000], [Diekert et al. 2012]), with the holonomy method the most popular and efficient in general (although not in all cases). Owing to the close relation between monoids and categories, a version of the Krohn–Rhodes theorem is applicable to category theory. This observation and a proof of an analogous result were offered by Wells (1980).
The Krohn–Rhodes theorem for semigroups/monoids is an analogue of the Jordan–Hölder theorem for finite groups (for semigroups/monoids rather than groups). As such, the theorem is a deep and important result in semigroup/monoid theory. The theorem was also surprising to many mathematicians and computer scientists since it had previously been widely believed that the semigroup/monoid axioms were too weak to admit a structure theorem of any strength, and prior work (Hartmanis & Stearns) was only able to show much more rigid and less general decomposition results for finite automata.
Work by Egri-Nagy and Nehaniv (2005, 2008–) continues to further automate the holonomy version of the Krohn–Rhodes decomposition extended with the related decomposition for finite groups (so-called Frobenius–Lagrange coordinates) using the computer algebra system GAP.
Applications outside of the semigroup and monoid theories are now computationally feasible. They include computations in biology and biochemical systems (e.g. Egri-Nagy & Nehaniv 2008), artificial intelligence, finite-state physics, psychology, and game theory (see, for example, Rhodes 2009).
See also
Semigroup action
Transformation semigroup
Green's relations
Notes
References
Egri-Nagy, A.; and Nehaniv, C. L. (2005), "Algebraic Hierarchical Decomposition of Finite State Automata: Comparison of Implementations for Krohn–Rhodes Theory", in 9th International Conference on Implementation and Application of Automata (CIAA 2004), Kingston, Canada, July 22–24, 2004, Revised Selected Papers, Editors: Domaratzki, M.; Okhotin, A.; Salomaa, K.; et al.; Springer Lecture Notes in Computer Science, Vol. 3317, pp. 315–316, 2005
Two chapters are written by Bret Tilson.
Krohn, K. R.; and Rhodes, J. L. (1962), "Algebraic theory of machines", Proceedings of the Symposium on Mathematical Theory of Automata'' (editor: Fox, J.), (Wiley–Interscience)
Erratum: Information and Control 11(4): 471 (1967), plus erratum.
Further reading
External links
Prof. John L. Rhodes, University of California at Berkeley webpage
SgpDec: Hierarchical Composition and Decomposition of Permutation Groups and Transformation Semigroups, developed by A. Egri-Nagy and C. L. Nehaniv. Open-source software package for the GAP computer algebra system.
An introduction to the Krohn-Rhodes Theorem (Section 5); part of the Santa Fe Institute Complexity Explorer MOOC Introduction to Renormalization, by Simon DeDeo.
Semigroup theory
Category theory
Finite automata | Krohn–Rhodes theory | Mathematics | 2,108 |
3,842,182 | https://en.wikipedia.org/wiki/Cord%20%28unit%29 | The cord is a unit of measure of dry volume used to measure firewood and pulpwood in the United States and Canada.
A cord is the amount of wood that, when "racked and well stowed" (arranged so pieces are aligned, parallel, touching, and compact), occupies a volume of . This corresponds to a well-stacked woodpile high, wide, and deep; or any other arrangement of linear measurements that yields the same volume.
The name cord probably comes from the use of a cord or string to measure it.
The face cord is a unit of volume for stacked firewood, 8 feet long, 4 feet wide, and 16 inches high—equal to 1/3 of a cord. The symbol for the unit is fc - cd.
Definitions
In Canada, the cord is legally defined by Measurement Canada. The cord is one of three legal standards for the sale of firewood in Canada: stacked cubic meter (or stere), cubic foot, and cord.
In the United States, the cord is defined by statute in most states. The U.S. National Institute of Standards and Technology Handbook 130, section 2.4.1.2, defines a cord and provides uniform regulations for the sale of fireplace and stove wood. In the metric system, wood is usually measured in steres and cubic meters: 1 stere = 1 m3 ≈ 0.276 cords.
Maine appears unique among U.S. states by also defining a "loose thrown cord" or pile of cut firewood: "A cord of in length shall mean the amount of wood, bark, and air contained in a space of ; and a cord of wood in length shall mean the amount of wood, bark, and air contained in a space of . [1981, c. 219 (amd).]"
Other non-official terms for firewood volume include standing cord, kitchen cord, running cord, face cord, fencing cord, country cord, long cord, and rick, all subject to local variation. These are usually taken to mean a well-stacked pile of wood in which the logs are shorter or longer than in a legal cord, to accommodate various burners. For example, a face cord commonly consists of wood that is long. The volume of a face cord therefore is typically 1/3 of the volume of a full cord even though it is long and high. A face cord is also called a rick in the midwestern United States.
The term is used in other English-speaking countries, such as New Zealand, but may not have a legal definition.
The corde was a unit of volume used before metrication in several French-speaking countries (France, Belgium and Luxembourg). Its value varied from depending on the region, corresponding approximately to 2 to 5 steres.
Heating value
One seasoned (dry) cord of Northern red oak with a heating value of has the heating equivalent of of fuel oil with a heating value of .
Australia
Until metrication in Australia, an imperial cord was a measurement for wood and firewood. The measurements for a cord of wood were 4 feet wide by 4 feet deep by 8 feet high, or usually a stack of wood containing 128 cubic feet (cu ft). The imperial cord enclosed 128 cu ft.
See also
Board foot
Cubic ton
Forest product
Hoppus foot
Imperial units
List of unusual units of measurement
Measurement Canada
Measurement Information Division of Industry Canada
Standard (timber unit)
Units of measurement
References
External links
Nova Scotia Natural Resources Information Circular DNR - 1A: "Guide to buying and measuring stacked firewood"
Customary units of measurement in the United States
Units of volume
Logging | Cord (unit) | Mathematics | 729 |
6,317,414 | https://en.wikipedia.org/wiki/238%20%28number%29 | 238 (two hundred [and] thirty-eight) is the natural number following 237 and preceding 239.
In mathematics
238 is an untouchable number.
There are 238 2-vertex-connected graphs on five labeled vertices, and 238 order-5 polydiamonds (polyiamonds that can partitioned into 5 diamonds). Out of the 720 permutations of six elements, exactly 238 of them have a unique longest increasing subsequence.
There are 238 compact and paracompact hyperbolic groups of ranks 3 through 10.
References
Integers | 238 (number) | Mathematics | 115 |
1,526,681 | https://en.wikipedia.org/wiki/Barricade | Barricade (from the French barrique - 'barrel') is any object or structure that creates a barrier or obstacle to control, block passage or force the flow of traffic in the desired direction. Adopted as a military term, a barricade denotes any improvised field fortification, such as on city streets during urban warfare.
Barricades also include temporary traffic barricades designed with the goal of dissuading passage into a protected or hazardous area or large slabs of cement whose goal is to prevent forcible passage by a vehicle. Stripes on barricades and panel devices slope downward in the direction traffic must travel.
There are also pedestrian barricades - sometimes called bike rack barricades for their resemblance to a now obsolete form of bicycle stand, or police barriers. They originated in France approximately 50 years ago and are now used around the world. They were first used in the U.S. 40 years ago by Friedrichs Mfg for New Orleans's Mardi Gras parades.
Anti-vehicle barriers and blast barriers are sturdy barricades that can respectively counter vehicle and bomb attacks.
In history
The origins of the barricade are often erroneously traced back to the "First Day of the Barricades", a confrontation that occurred in Paris on 12 May 1588 in which the supporters of the Duke of Guise and the ultra-Catholic Holy League successfully challenged the authority of King Henri III. In actuality, although barricades came to widespread public awareness in that uprising (and in the equally momentous "Second Day of the Barricades" on 27 August 1648), none of several conflicting claims concerning who may have "invented" the barricade stand up to close scrutiny for the simple reason that Blaise de Monluc had already documented insurgents' use of the technique at least as early as 1569 in religiously based conflicts in southwestern France.
Although barricade construction began in France in the sixteenth century and remained an exclusively French practice for two centuries, the nineteenth century remained the classic era of the barricade. Contrary to a number of historical sources, barricades were present in various incidents of the great French Revolution of 1789, but they never played a central role in those events. They were, however, a highly visible and consequential element in many of the insurrections that occurred in France throughout the 1800s, including in the revolutions of 1830 ("the July Days") and 1848 (in both February and June.) Other Parisian events included the June Rebellion of 1832, which was smaller in scale, but rendered famous by Victor Hugo's account in Les Misérables, the combat that ended the Paris Commune in May 1871, and the more symbolic structures created in May 1968.
The barricade began its diffusion outside France in the 1780s and played a significant role in the Belgian Revolution of 1830, but it was only in the course of the upheaval of 1848 that it became truly international in scope. Its spread across the Continent was aided by the circulation of students, political refugees, and itinerant workers through the French capital, where many gained first-hand experience of one or another Parisian insurrection. The barricade had, by the middle of the nineteenth century, become the preeminent symbol of a revolutionary tradition that would ultimately spread worldwide. Barricade references appear in many colloquial expressions and are used, often metaphorically, in poems and songs celebrating radical social movements.
Crowd control
Barricades are used for crowd control applications at public events or during exceptionally busy shopping times. Different types of barricade are designed to fit the environment and use cases the organizer decides on.
Bridge Feet Typically used for outdoor use, where the ground is not perfectly flat. The bridge design of the feet allows for better stability.
Flat FeetUsed on surfaces such as streets, sidewalks, and tarmacs, these barricades are designed for use on flat surfaces.
Heavy Duty Feet Similar to flat feet, but larger in size and made of heavy duty steel, allowing for more durability and support.
Barricade Gates These gates swing open like a doorway, allowing for passage of people of goods through a run of barricades.
Expanding Barricades Designed for indoor use and for use on sites where construction or work is occurring. Easy to move and store these barricades serve as a temporary barricade.
Gallery
See also
The Barricades
Bulwark
Border barrier
Rampart
Ley Anti Barricadas
Jersey barrier
A las Barricadas ('To the Barricades')
References
Traffic signs
Types of wall
Fortifications by type | Barricade | Engineering | 934 |
64,514,712 | https://en.wikipedia.org/wiki/Vector-valued%20Hahn%E2%80%93Banach%20theorems | In mathematics, specifically in functional analysis and Hilbert space theory, vector-valued Hahn–Banach theorems are generalizations of the Hahn–Banach theorems from linear functionals (which are always valued in the real numbers or the complex numbers ) to linear operators valued in topological vector spaces (TVSs).
Definitions
Throughout and will be topological vector spaces (TVSs) over the field and will denote the vector space of all continuous linear maps from to , where if and are normed spaces then we endow with its canonical operator norm.
Extensions
If is a vector subspace of a TVS then has the extension property from to if every continuous linear map has a continuous linear extension to all of . If and are normed spaces, then we say that has the metric extension property from to if this continuous linear extension can be chosen to have norm equal to .
A TVS has the extension property from all subspaces of (to ) if for every vector subspace of , has the extension property from to . If and are normed spaces then has the metric extension property from all subspace of (to ) if for every vector subspace of , has the metric extension property from to .
A TVS has the extension property if for every locally convex space and every vector subspace of , has the extension property from to .
A Banach space has the metric extension property if for every Banach space and every vector subspace of , has the metric extension property from to .
1-extensions
If is a vector subspace of normed space over the field then a normed space has the immediate 1-extension property from to if for every , every continuous linear map has a continuous linear extension such that . We say that has the immediate 1-extension property if has the immediate 1-extension property from to for every Banach space and every vector subspace of .
Injective spaces
A locally convex topological vector space is injective if for every locally convex space containing as a topological vector subspace, there exists a continuous projection from onto .
A Banach space is 1-injective or a -space if for every Banach space containing as a normed vector subspace (i.e. the norm of is identical to the usual restriction to of 's norm), there exists a continuous projection from onto having norm 1.
Properties
In order for a TVS to have the extension property, it must be complete (since it must be possible to extend the identity map from to the completion of ; that is, to the map ).
Existence
If is a continuous linear map from a vector subspace of into a complete Hausdorff space then there always exists a unique continuous linear extension of from to the closure of in .
Consequently, it suffices to only consider maps from closed vector subspaces into complete Hausdorff spaces.
Results
Any locally convex space having the extension property is injective.
If is an injective Banach space, then for every Banach space , every continuous linear operator from a vector subspace of into has a continuous linear extension to all of .
In 1953, Alexander Grothendieck showed that any Banach space with the extension property is either finite-dimensional or else separable.
{{Math theorem|name=Theorem |math_statement=
Suppose that is a Banach space over the field
Then the following are equivalent:
is 1-injective;
has the metric extension property;
has the immediate 1-extension property;
has the center-radius property;
has the weak intersection property;
is 1-complemented in any Banach space into which it is norm embedded;
Whenever in norm-embedded into a Banach space then identity map can be extended to a continuous linear map of norm to ;
is linearly isometric to for some compact, Hausdorff space, extremally disconnected space . (This space is unique up to homeomorphism).
where if in addition, is a vector space over the real numbers then we may add to this list:
has the binary intersection property;
is linearly isometric to a complete Archimedean ordered vector lattice with order unit and endowed with the order unit norm.
}}
Examples
Products of the underlying field
Suppose that is a vector space over , where is either or and let be any set.
Let which is the product of taken times, or equivalently, the set of all -valued functions on .
Give its usual product topology, which makes it into a Hausdorff locally convex TVS.
Then has the extension property.
For any set the Lp space has both the extension property and the metric extension property.
See also
Citations
References
Topological vector spaces
Theorems in functional analysis | Vector-valued Hahn–Banach theorems | Mathematics | 950 |
5,057,796 | https://en.wikipedia.org/wiki/School%20of%20Electrical%20Engineering%20and%20Computer%20Science%20%28University%20of%20Ottawa%29 | The School of Electrical Engineering and Computer Science, is an academic unit within The Faculty of Engineering, at the University of Ottawa. Until 2011 it was called the School of Information Technology and Engineering (SITE), which remains the name of a building on the southern edge of campus.
It was formed in 1997 by the merger of the Department of Computer Science and of the Department of Electrical and Computer Engineering.
It teaches undergraduate programs in Electrical Engineering, Software Engineering, Computer Engineering and Computer Science, and offers education up to the PhD level.
External links
EECS website in English and French
University of Ottawa
Electrical engineering departments
Electrical and computer engineering departments
1997 establishments in Ontario
Educational institutions established in 1997
Computer science departments in Canada | School of Electrical Engineering and Computer Science (University of Ottawa) | Engineering | 141 |
76,396,726 | https://en.wikipedia.org/wiki/Russula%20violacea | Russula violacea, is a species of agaric fungus in the family Russulaceae first described by Lucien Quélet.
Distribution and habitat
R. violacea has been noted in North America, Asia and Europe, with the most occurrences in Europe. It grows in coniferous
and deciduous forests, under Quercus, Betula and Populus trees, it has been also spotted on coal dumps. It fruits between August and October.
References
External links
violacea
Fungi described in 1883
Fungus species | Russula violacea | Biology | 101 |
14,816,689 | https://en.wikipedia.org/wiki/NUTF2 | Nuclear transport factor 2 is a protein that in humans is encoded by the NUTF2 gene.
Function
The protein encoded by this gene is a cytosolic factor that facilitates protein transport into the nucleus. It interacts with the nuclear pore complex glycoprotein p62. This encoded protein acts at a relative late stage of nuclear protein import, subsequent to the initial docking of nuclear import ligand at the nuclear envelope. It is thought to be part of a multicomponent system of cytosolic factors that assemble at the pore complex during nuclear import.
Interactions
NUTF2 has been shown to interact with Nucleoporin 62 and RAN.
References
Further reading
External links | NUTF2 | Chemistry | 140 |
21,632,363 | https://en.wikipedia.org/wiki/Capravirine | Capravirine was a non-nucleoside reverse transcriptase inhibitor which reached phase II trials before development was discontinued by Pfizer. Both phase IIb trials which were conducted failed to demonstrate that therapy with capravirine provided any significant advantage over existing triple-drug HIV therapies, and pharmacology studies showed that capravirine may interact with other HIV drugs.
References
Abandoned drugs
Carbamates
Chlorobenzene derivatives
Imidazoles
4-Pyridyl compounds
Isopropyl compounds
Thioethers | Capravirine | Chemistry | 115 |
24,692,513 | https://en.wikipedia.org/wiki/Ankaramite | Ankaramite is volcanic rock type of mafic composition. It is a dark porphyritic variety of basanite containing abundant pyroxene and olivine phenocrysts. It contains minor amounts of plagioclase and accessory biotite, apatite, and iron oxides.
Its type locality is Ankaramy in Madagascar. It was first described in 1916. It is also found in the Sierra de Guanajuato of Central Mexico, the South Pacific on islands such as Tahiti, Rarotonga, Samoa and in the Zealandia, Alexandra Volcanic Group.
References
Porphyritic rocks
Mafic rocks
Volcanic rocks | Ankaramite | Chemistry | 135 |
1,233,983 | https://en.wikipedia.org/wiki/Tobacco%20packaging%20warning%20messages | Tobacco package warning messages are warning messages that appear on the packaging of cigarettes and other tobacco products concerning their health effects. They have been implemented in an effort to enhance the public's awareness about the harmful effects of smoking. In general, warnings used in different countries try to emphasize the same messages. Warnings for some countries are listed below. Such warnings have been required in tobacco advertising for many years, with the earliest mandatory warning labels implemented in the United States in 1966. Implementing tobacco warning labels has been strongly opposed by the tobacco industry, most notably in Australia, following the implementation of plain packaging laws.
The WHO Framework Convention on Tobacco Control, adopted in 2003, requires such warning messages to promote awareness against smoking.
The effectiveness of tobacco warning labels has been studied extensively over the past 50 years, and research shows that they are generally effective in changing smoking attitudes and behaviors. A 2009 science review determined that there is "clear evidence that tobacco package health warnings increase consumers' knowledge about the health consequences of tobacco use". The warning messages "contribute to changing consumers' attitudes towards tobacco use as well as changing consumers' behavior".
Despite the demonstrated benefits of warning labels, the efficacy of fear-based messaging in reducing smoking behaviors has been subject to criticism. A 2007 meta-analysis demonstrated that messages emphasizing the severity of threat may be less effective at changing behaviors than messages focusing on susceptibility to threat, suggesting that extremely graphic warning labels are no more effective than labels that simply state the negative consequences of a behavior. Additionally, the study found that warning labels may not be effective among smokers who are not confident that they can quit, leading the authors to recommend exploring other methods of behavior modification.
In many countries, a variety of warnings with graphic, disturbing images of tobacco-related harms (including hematuria and diabetes) are placed prominently on cigarette packages.
Albania
As of 2020, all tobacco products in Albania must have one of the following general warning on the packaging: "Smoking kills - quit now" or "Smoking kills". Additionally, packaging must contain an information message about the product, as follows: "Tobacco contains over 70 substances that cause cancer". The general warning and the information message must occupy 50% of the packaging area of the side on which they are printed. Albania also requires the use of combined warnings that includes the text warning and a colored image, which must cover 65% of the front and back area of the packaging.
Text-based general warning label used on tobacco packages in Albania:
Argentina
General warning (former):
As of 30 January 2013, all cigarette packages must include graphical warning labels that show the detrimental effects on the health of long-term smokers, including COVID-19 (added in 2022).
Australia
On 1 December 2012, Australia introduced ground-breaking legislation and the world's toughest tobacco packaging warning messages to date. All marketing and brand devices were removed from the package and replaced with warnings, only the name of the product remains in generic standard sized text. All tobacco products sold, offered for sale or otherwise supplied in Australia were plain-packaged and labelled with new and expanded health warnings.
Azerbaijan
In Azerbaijan, a text-only health warning in the Azeri language, "Smoking harms your health", is required to cover 30% of the front and back of the package. There is no requirement for rotation, and there is only one required health warning. Misleading packaging and labeling, including terms such as "light" and "mild," is prohibited.
Bangladesh
The law requires rotating pictorial health warnings to cover at least 50% of the main display areas of all tobacco products. Misleading terms such as "light" and "low tar" are prohibited on tobacco packaging, but other misleading packaging (e.g., colors, numbers, and symbols) is not banned.
Belgium
Belgium became a Party to the WHO Framework Convention on Tobacco Control on January 30, 2006. Belgium implemented their current health warnings policy starting April 2007.
Including the border, health warnings cover 48% of the front and 63% of the back of cigarette packages, which is larger than the EU requirements of 35% front and 50% back because Belgium is a trilingual country (German, French, Flemish). Overall, 56% of the package space is appropriated to health warnings. Since 2011, three different sets of 14 warnings have been rotated every 12 months.
Belgium prohibits the terms "light" and "mild" from appearing on packages.
Additionally, Belgium requires tar, nicotine, and carbon monoxide emission numbers to appear on the side of packages. These emission numbers are generated using the ISO machine smoking method.
Bolivia
In Bolivia, a variety of warnings with graphic, disturbing images of tobacco-related harms (including laryngeal cancer and heart attack) are placed prominently on cigarette packages.
Bosnia and Herzegovina
Front of packaging (covers 30% of surface):
Pušenje je štetno za zdravlje (Smoking is harmful to health)
Pušenje ubija (Smoking kills)
Pušenje ozbiljno šteti vama i drugima oko vas (Smoking seriously harms you and others around you)
Back of packaging (covers 50% of surface):
Pušenje uzrokuje rak pluća (Smoking causes lung cancer)
Pušenje uzrokuje srčani udar (Smoking causes heart attacks)
Pušenje uzrokuje moždani udar (Smoking causes strokes)
Pušenje u trudnoći šteti zdravlju Vašeg djeteta (Smoking while pregnant harms your child)
Before 2011, a small warning with the text Pušenje je štetno za zdravlje (Smoking is harmful to health) was printed on the back of cigarette packets.
Brazil
In 2001, Brazil became the second country in the world and the first country in Latin America to adopt mandatory warning images in cigarette packages. Warnings and graphic images illustrating the risks of smoking occupy 100% of the back of cigarette packs. In 2008, the government enacted a third batch of images aimed at younger smokers. The rule was in force for nine years until 2017, when yet another batch of warnings were introduced. They contain images as equally disturbing as the previous ones but also contain subtle messages such as "Você morre" (You die), "Você sofre" (You suffer) and "Você adoece" (You get sick).
Since 2003, the sentence
is displayed in all packs.
Brunei
The following warnings appear on Bruneian cigarette packages since 2007:
(Smoking causes various cancers)
(Smoking causes strokes and heart disease)
(Smoking kills)
(Smoking damages your teeth)
(Tobacco smoke harms your baby)
(Tobacco smoke can kill babies)
(Smoking causes lung cancer)
(Smoking causes impotence)
Cambodia
In Cambodia, a variety of warnings with graphic, disturbing images of tobacco-related harms (including premature birth and lung cancer) are placed prominently on cigarette packages.
Canada
Canada has had three phases of tobacco warning labels. The first set of warnings was introduced in 1989 under the Tobacco Products Control Act, and required warnings to be printed on all tobacco products sold legally in Canada. The set consisted of four messages printed in black-and-white on the front and back of the package, and was expanded in 1994 to include eight messages covering 25% of the front top of the package.
In 2000, the Tobacco Products Information Regulations (TPIR) were passed under the Tobacco Act. The regulations introduced a new set of sixteen warnings. Each warning was printed on the front and back of the package, covering 50% of the surface, with a short explanation and a picture illustrating that particular warning, for example:
accompanied by a picture of cancerous growths inside a human lung.
Additionally, on the inside of the packaging or, for some packets, on a pull-out card, "health information messages" provide answers and explanations regarding common questions and concerns about quitting smoking and smoking-related illnesses. The side of the package also featured information on toxic emissions and constituent levels.
In 2011, the TPIR were replaced for cigarettes and little cigars with the Tobacco Products Labelling Regulations (Cigarettes and Little Cigars). These regulations introduced the third and current set of 16 warnings in Canada. Currently, cigarette and little cigar packages in Canada must bear new graphic warning messages that cover 75% of the front and back of the package. The interior of each package contains 1 of 8 updated health warning messages, all including the number for a national quitline. The side of the package now bears 1 of 4 simplified toxic emission statements. These labels were fully implemented on cigarette and little cigar packages by June 2012 (though the 2000 labels still appear on other tobacco products). Canada also prohibits terms such as "light" and "mild" from appearing on tobacco packaging. The current labels were based on extensive research and a long consultation process that sought to evaluate and improve upon the warnings introduced in 2000.
In accordance with Canadian law regarding products sold legally in Canada, the warnings are provided in both English and French. Imported cigarettes to be sold in Canada which do not have the warnings are affixed with sticker versions when they are sold legally in Canada.
Health Canada considered laws mandating plain packaging, legal tobacco product packaging did still include warning labels, but brand names, fonts, and colors were replaced with simple unadorned text, thereby reducing the impact of tobacco industry marketing techniques.
There have been complaints from some Canadians due to the graphic nature of the labels. It was mandated in January 2020.
Canada became the first country in the world to require health warnings on each individual cigarettes and cigars, effective August 1, 2023, to be phased in over time when the regulation is fully in effect by April 2025.
Chile
Starting in November 2006, all cigarette packages sold in Chile are required to have one of two health warnings, a graphic pictorial warning or a text-only warning. These warnings are replaced with a new set of two warnings each year.
China
Under laws of the People's Republic of China, the Law on Tobacco Monopoly (中华人民共和国烟草专卖法) Chapter 4, Article 18 and Regulations for the Implementation of the Law on Tobacco Monopoly (中华人民共和国烟草专卖法实施条例) Chapter 5 Article 29, cigarettes and cigars sold within Mainland China should indicate the grade of tar content and "Smoking is hazardous to your health" (吸烟有害健康) in the Chinese language on the packs and cartons.
In 2009, the warnings were changed. The warnings, which occupy not less than 30% of the front and back of cigarette packs, show "吸烟有害健康 尽早戒烟有益健康" (Smoking is harmful to your health. Quitting smoking early is good for your health) in the front and "吸烟有害健康 戒烟可减少对健康的危害" (Smoking is harmful to your health. Quitting smoking can reduce health risks) in the back.
The warnings were revised in October 2016 and must occupy at least 35% of the front and back of cigarette packs. The following are the current warnings.
In the front:
本公司提示吸烟有害健康请勿在禁烟场所吸烟
("Our company notes that smoking is harmful to your health. Do not smoke in non-smoking areas" in Chinese)
In the back:
尽早戒烟有益健康戒烟可减少对健康的危害
("Quitting smoking as soon as possible is good for your health. It can also reduce health risks" in Chinese)
or
劝阻青少年吸烟禁止中小学生吸烟
("Dissuade teenagers from smoking. Prohibit primary and middle school students from smoking" in Chinese)
Colombia
In Colombia, a variety of warnings with graphic, disturbing images of tobacco-related harms (including clogged arteries and bladder cancer) are placed prominently on cigarette packages.
Costa Rica
In Costa Rica, a variety of warnings with graphic, disturbing images of tobacco-related harms (including lung cancer and heart attack) are placed prominently on cigarette packages.
East Timor
East Timor only used a text warning, "FUMA OHO ITA" (Smoking kills), prior to 2018, when new pictorial warnings covering 85% of the front and 100% of the back of packages were implemented.
The warnings currently in use are:
FUMA OHO ITA (Smoking kills), featuring a crucifix made of cigarettes placed on a pile of human skulls.
FUMA KAUZA IMPOTÉNSIA (Smoking causes impotence)
FUMA PROVOKA MORAS FUAN (Smoking can cause heart attacks)
FUMA KAUZA ABORTU (Smoking causes abortions)
FUMA PROVOKA KANKRU (Smoking can cause cancer)
FUMA KAUZA PULMAUN KRONIKU (Smoking causes chronic lung disease)
Konsulta atu para fuma – Numero telf: 113 (Consultation for quitting smoking – Phone number: 113), accompanying all of these warnings.
Ecuador
In Ecuador, a variety of warnings with graphic, disturbing images of tobacco-related harms (including tongue cancer and premature birth) are placed prominently on cigarette packages.
Egypt
In Egypt, a variety of warnings with graphic, disturbing images of tobacco-related harms (including mouth cancer and gangrene) are placed prominently on cigarette packages.
European Union
Cigarette packets and other tobacco packaging must include warnings in the same size and format and using the same approved texts (in the appropriate local languages) in all member states of the European Union.
These warnings are displayed in black Helvetica bold on a white background with a thick black border. Ireland once prefaced its warnings with "Irish Government Warning", Latvia with "Veselības ministrija brīdina" (Health Ministry Warning) and Spain with "Las autoridades sanitarias advierten" ("The Health Board Warns"). In member states with more than one official language, the warnings are displayed in all official languages, with the sizes adjusted accordingly (for example in Belgium the messages are written in Dutch, French and German, in Luxembourg in French and German and in Ireland, in Irish and English). All cigarette packets sold in the European Union used to have to display the content of nicotine, tar, and carbon monoxide in the same manner on the side of the packet, this is no longer the case.
In 2003, it was reported that sales of cigarette cases had surged, attributable to the introduction of more prominent warning labels on cigarette packs by an EU directive in January 2003. Alternatively, people choose to hide the warnings using various "funny" stickers, such as "You could be hit by a bus tomorrow."
The most recent EU legislation is the Tobacco Products Directive, which became applicable in EU countries in May 2016.
front, takes up 30%
reverse, takes up 40%
Austria and Germany
General warnings
Rauchen fügt Ihnen und den Menschen in Ihrer Umgebung erheblichen Schaden zu. – Smoking severely harms you and the people around you.
Additional warnings
Raucher sterben früher – Smokers die younger.
Rauchen führt zur Verstopfung der Arterien und verursacht Herzinfarkte und Schlaganfälle. – Smoking leads to clogging of arteries and causes heart attacks and strokes.
Rauchen verursacht tödlichen Lungenkrebs. – Smoking causes deadly lung cancer.
Rauchen in der Schwangerschaft schadet Ihrem Kind – Smoking while pregnant harms your child.
Schützen Sie Kinder – lassen Sie sie nicht Ihren Tabakrauch einatmen! – Protect children – don't let them inhale your tobacco smoke!
Ihr Arzt oder Apotheker kann Ihnen dabei helfen, das Rauchen aufzugeben. – Your doctor or pharmacist can help you to give up smoking.
Rauchen macht sehr schnell abhängig: Fangen Sie gar nicht erst an! – Smoking makes you addicted very fast: Don't start in the first place!
Wer das Rauchen aufgibt, verringert das Risiko tödlicher Herz- und Lungenerkrankungen – Giving up smoking reduces the risk of fatal heart and lung diseases.
Rauchen kann zu einem langsamen und schmerzhaften Tod führen – Smoking can lead to a slow and painful death.
Rauchen kann zu Durchblutungsstörungen führen und verursacht Impotenz – Smoking can lead to blood circulation disorders and causes impotence.
Rauchen lässt Ihre Haut altern – Smoking ages your skin.
Rauchen kann die Spermatozoen schädigen und schränkt die Fruchtbarkeit ein – Smoking can damage the spermatozoa and decreases your fertility.
Rauch enthält Benzol, Nitrosamine, Formaldehyd und Blausäure – Smoke contains benzene, nitrosamine, formaldehyde and hydrogen cyanide.
Belgium
In Belgium, warning signs are written in Dutch, French and German, the three official languages of Belgium.
Croatia
Front of packaging (covers 30% of surface):
or
Back of packaging (covers 40% of surface):
Pušači umiru mlađi (Smokers die younger)
Pušenje uzrokuje začepljenje arterija i uzrokuje srčani i moždani udar (Smoking clogs your arteries and causes heart attacks and strokes)
Pušenje uzrokuje smrtonosan rak pluća (Smoking causes fatal lung cancer)
Pušenje u trudnoći šteti vašem djetetu (Smoking while pregnant harms your child)
Zaštitite djecu od udisanja vašeg cigaretnog dima (Protect children from inhaling your cigarette smoke)
Vaš liječnik ili ljekarnik može vam pomoći prestati pušiti (Your doctor or pharmacist can help you stop smoking)
Pušenje stvara izrazitu ovisnost, nemojte ni počinjati (Smoking is highly addictive, don't even start)
Prestanak pušenja umanjuje rizik smrtnih srčanih ili plućnih bolesti (Quitting smoking reduces the risk of deadly heart and lung diseases)
Pušenje može izazvati polaganu i bolnu smrt (Smoking can cause a slow and painful death)
Potražite pomoć za prestanak pušenja /savjetujte se sa svojim liječnikom/ljekarnikom) (Get help to stop smoking /consult with your doctor/pharmacist)
Pušenje može usporiti krvotok i prouzročiti impotenciju (Smoking can slow down blood circulation and cause impotence)
Pušenje uzrokuje starenje kože (Smoking causes aging of the skin)
Pušenje može oštetiti spermu i smanjiti plodnost (Smoking can damage sperm and reduce fertility)
Dim sadrži benzene, nitrozamine, formaldehide i ugljikove cijanide (Smoke contains benzene, nitrosamines, formaldehyde and hydrogen cyanides*)
The last warning contains a mistranslation from Directive 2001/37/EC – "hydrogen" was translated as ugljik (carbon) instead of vodik. It was nevertheless signed into law and started appearing on cigarette packages in March 2009.
2004–2009
These warnings were also simple text warnings.
Front of packaging:
Pušenje šteti Vašem zdravlju (Smoking harms your health)
Back of packaging:
Pušenje uzrokuje rak (Smoking causes cancer)
Pušenje u trudnoći šteti i razvoju djeteta (Smoking while pregnant harms the child's development)
Pušenje uzrokuje srčani i moždani udar (Smoking causes heart attacks and strokes)
Pušenje skraćuje život (Smoking shortens your life)
Side of packaging:
Zabranjuje se prodaja osobama mlađim od 18 godina (Not for sale to persons under the age of 18)
1997–2004
Between 1997 and 2004, a simple text label warning, Pušenje je štetno za zdravlje (Smoking is harmful to health), was used.
Cyprus
Front side
or
Rear
(Smokers die younger.)
(Smoking clogs the arteries and causes heart attacks and strokes.)
(Smoking causes terminal lung cancer.)
(Smoking during pregnancy may harm your baby.)
(Protect children: don't make them breathe your smoke.)
(Your doctor or your pharmacist can help you stop smoking.)
(Smoking is highly addictive, don't start.)
(Stopping smoking reduces the risk of fatal heart and lung diseases.)
(Smoking can cause a slow and painful death.)
(Smoking may reduce the blood flow and cause impotence.)
(Smoking causes ageing of the skin.)
(Smoking can damage the sperm and decreases fertility.)
(Smoke contains benzene, nitrosamines, formaldehyde and hydrogen cyanide.)
Czech Republic
Kouření vážně škodí Vám i lidem ve Vašem okolí. (Smoking seriously harms you and others around you.)
Kuřáci umírají předčasně. (Smokers die younger.)
Kouření ucpává tepny a způsobuje infarkt a mrtvici. (Smoking clogs the blood vessels and causes heart attacks and strokes.)
Kouření způsobuje smrtelnou rakovinu plic. (Smoking causes deadly lung cancer.)
Kouření je vysoce návykové, nezačínejte s ním. (Smoking is highly addictive, don't start.)
Přestat kouřit, znamená snížit riziko vzniku smrtelných onemocnění srdce a plic. (Quitting smoking reduces the risk of deadly heart and lung diseases.)
Kouření může způsobit pomalou a bolestivou smrt. (Smoking can cause a slow and painful death.)
Kouření způsobuje stárnutí kůže. (Smoking causes ageing of the skin.)
Kouření může poškodit sperma a snižuje plodnost. (Smoking can damage sperm and reduce fertility.)
Kouření může snižovat krevní oběh a způsobuje neplodnost. (Smoking can reduce blood flow and cause impotence.)
Kouř obsahuje benzen, nitrosaminy, formaldehyd a kyanovodík. (Smoke contains benzene, nitrosamines, formaldehyde and hydrogen cyanides.)
Kouření v těhotenství škodí zdraví Vašeho dítěte. (Smoking while pregnant harms your child.)
Chraňte děti: nenuťte je vdechovat Váš kouř. (Protect children: don't make them breathe your smoke.)
Váš lékař nebo lékárník Vám může pomoci přestat s kouřením. (Your doctor or pharmacist can help you stop smoking.)
Získejte pomoc při odvykání kouření. (Seek help to stop smoking.)
As of 7 December 2016, all packages must also include warning images additionally to text warnings. Also cigarette manufacturers are prohibited to display the content of nicotine, tar and carbon monoxide on cigarette packages, because it might mislead customers. The box previously containing the contents of the cigarette was replaced by a warning message: Tabákový kouř obsahuje přes 70 látek, které prokazatelně způsobují rakovinu. (Tobacco smoke contains over 70 substances, which provably cause cancer.)
Denmark
Warning texts in tobacco products, health warnings, which are reproduced on the packaging of cigarettes and other tobacco products. It is implemented in an effort to strengthen public knowledge about the dangers of smoking.
The order was introduced in Denmark on 31 December 1991. The Order was last revised on 2 October 2003, which also imposed ban on the words "light" and "mild" on Danish cigarette packages, as did European Union countries.
The marking shall appear on one third of the most visible part of the package.
(Smoking seriously harms you and others around you)
(Smokers die younger)
(Smoking clogs the arteries and causes heart attacks and strokes)
(Smoking causes fatal lung cancer)
(If you are pregnant, smoking damages your child's health)
(Protect children from tobacco smoke – they have the right to choose)
(Your doctor or your pharmacist can help you stop smoking)
Rygning er årsag til 9 ud af 10 tilfælde af lungekræft (Smoking causes 9 out of 10 cases of lung cancer)
(Smoking is highly addictive, do not start)
(Stopping smoking reduces the risk of fatal heart and lung diseases)
(Smoking can cause a slow and painful death)
(Get help to quit smoking: Telephone number 80313131)
(Smoking may reduce blood flow and causes impotence)
(Smoking causes aging of the skin)
(Smoking can damage sperm and reduce fertility)
(Smoke contains benzene, nitrosamines, formaldehyde and hydrogen cyanide)
For smokeless tobacco use above markings does not, whereas the label "" (This tobacco product can damage your health and is addictive) is always used for such products.
Estonia
General warning:
or
Finland
In Finland, warning signs are written in both Finnish and Swedish languages.
Tupakointi vahingoittaa vakavasti sinua ja ympärilläsi olevia / Rökning skadar allvarligt dig själv och personer i din omgivning (Smoking severely harms you and those around you)
Tupakoivat kuolevat nuorempina / Rökare dör i förtid (Smokers die younger)
Tupakointi tukkii verisuonet sekä aiheuttaa sydänkohtauksia ja aivoveritulppia / Rökning ger förträngningar i blodkärlen och orsakar hjärtinfarkt och stroke (Smoking clogs the arteries and causes heart attacks and strokes)
Tupakointi aiheuttaa keuhkosyöpää, joka johtaa kuolemaan / Rökning orsakar dödlig lungcancer (Smoking causes lung cancer, which leads to death / Smoking causes fatal lung cancer)
Tupakointi raskauden aikana vahingoittaa lastasi / Rökning under graviditeten skadar ditt barn (Smoking during pregnancy harms your child)
Suojele lapsia ― älä pakota heitä hengittämään tupakansavua / Skydda barnen ― låt dem inte andas in din tobaksrök (Protect children ― don't force them to breathe tobacco smoke / Protect children ― don't make them breathe your smoke)
Lääkäriltä tai apteekista saat apua tupakoinnin lopettamiseen / Din läkare eller ditt apotek kan hjälpa dig att sluta röka (You receive help to stop smoking from a doctor or a pharmacy / Your doctor or your pharmacist can help you stop smoking)
Tupakointi aiheuttaa voimakasta riippuvuutta. Älä aloita / Rökning är mycket beroendeframkallande. Börja inte rök (Smoking causes powerful addiction. Don't start / Smoking is highly addictive. Don't start)
Lopettamalla tupakoinnin vähennät vaaraa sairastua kuolemaan johtaviin sydän- ja keuhkosairauksiin / Om du slutar röka löper du mindre risk att få dödliga hjärt- och lungsjukdomar (By stopping smoking you reduce the risk of fatal heart and lung diseases / Stopping smoking reduces the risk of fatal heart and lung diseases)
Tupakointi voi aiheuttaa hitaan ja tuskallisen kuoleman / Rökning kan leda till en långsam och smärtsam död (Smoking can cause a slow and painful death)
Pyydä apua tupakoinnin lopettamiseen: puh. 0800 148 484 / Sök hjälp för att sluta röka: tfn 0800 148 484 (Request help to stop smoking: call 0800 148 484 / Get help to stop smoking: call 0800 148 484)
Tupakointi aiheuttaa impotenssia ja voi heikentää verenkiertoa / Rökning kan försämra blodflödet och orsakar impotens (Smoking causes impotence and may reduce the blood flow / Smoking may reduce the blood flow and cause impotence)
Tupakointi vanhentaa ihoa / Rökning får din hy att åldras (Smoking ages the skin / Smoking causes ageing of the skin)
Tupakointi voi vahingoittaa siittiöitä ja vähentää hedelmällisyyttä / Rökning kan skada sperman och minskar fruktsamheten (Smoking can damage the sperm and decrease fertility / Smoking can damage the sperm and decreases fertility)
Savu sisältää bentseeniä, nitrosamiineja, formaldehydiä ja vetysyanidia / Rök innehåller bensen, nitrosaminer, formaldehyd och cyanväte (Smoke contains benzene, nitrosamines, formaldehyde and hydrogen cyanide)
France
Before January 2017, France used regular EU warnings for tobacco products.
Front of packaging (covers 30% of surface)
or
Rear (covers 40% of surface, similar design)
(Smokers die prematurely.)
(Smoking clogs arteries and causes heart attacks and strokes.)
(Smoking causes fatal lung cancer.)
(Smoking during pregnancy harms your child's health.)
(Protect your children: don't make them breathe your smoke.)
(Your doctor or pharmacist can help you quit smoking.)
(Smoking is highly addictive, don't start.)
(Quitting smoking reduces the risk of fatal heart and lung diseases.)
(Smoking can result in a slow and painful death.)
(Help yourself quit smoking: call 0 825 309 310)
(Smoking can reduce the blood flow and causes impotence.)
(Smoking damages sperm and reduces fertility.)
(Cigarette smoke contains benzene, nitrosamines, formaldehyde and hydrogen cyanide.)
Left or right side of packaging
Components percentages (15% of surface, small prints): Tobacco – Cigarette paper – Flavor and texture agents
ISO yields of toxics in mg/cigarette (in prominent black on white square and bold letters): Tar – Nicotin – Carbon monoxide
Other side of packaging
Country of manufacturing, name of manufacturer, quantity
Product identifier (EAN-7 bar code)
Other characteristics
Small print: "" (sales in France)
Recyclable logo (for the packaging)
Words forbidden in the displayed product name: light, ultra-light, légere, or any indication that may indicate that this is a minor drug with low impact (These branding words have been replaced by various colour names)
Plain packaging has been regulated since January 2017.
Greece
(Smoking can kill)
(Smoking seriously harms the smoker and the ones around them.)
(Smoking seriously harms you and the ones around you.)
(Smokers die prematurely.)
(Smoking clogs the arteries and causes heart attacks and strokes.)
(Smoking causes fatal lung cancers.)
(Smoking during pregnancy can harm the health of your baby.)
(Protect children: do not force them to breathe in your smoke.)
(Your physician or pharmacist can assist you in quitting smoking.)
(Smoking is very addictive; don't start with it)
(Stopping smoking reduces the risk of fatal heart and lung diseases)
(Smoking can cause a slow and painful death.)
(Seek help to quit smoking: consult your doctor.)
(Smoking may reduce blood circulation and cause impotence)
(Smoking causes premature skin aging.)
(Smoking damages sperm and reduces fertility.)
(Cigarette smoke contains benzene, nitrosamines, formaldehyde and hydrogen cyanide.)
Hungary
(Smokers die earlier.)
(Smoking clogs arteries and causes heart diseases and strokes.)
(Smoking causes fatal lung cancer.)
(Smoking during pregnancy harms the baby.)
(Protect the kids, don't smoke in their presence.)
(Your doctor or your pharmacist may help you quit smoking.)
(Smoking is highly addictive, don't start.)
(Quitting smoking reduces the risk of deadly cardiovascular and lung diseases.)
(Smoking can cause a long and painful death.)
(Specialists in the medical profession may help you quit smoking.)
(Smoking may reduce blood circulation and cause impotency.)
(Smoking ages the skin.)
(Smoking may damage sperm and diminish fertility.)
(Cigarettes contain benzene, nistrosamine, formaldehyde and hydrocyanic acid.)
Ireland
Ireland currently follows EU standards (see above), but previously ran its own scheme, where one of 8 messages was placed on the pack, as defined in SI 326/1991.
After a High Court settlement in January 2008, it was accepted that the warnings on tobacco products must appear in both official languages of the state. As a result, the European Communities (Manufacture, Presentation
and Sale of Tobacco Products) (Amendment) Regulations 2008 were put in place. This provides that tobacco products going to market after 30 September 2008 must carry warnings in Irish and English. A year-long transition period applied to products which were on the market prior to 1 October 2008, which may have been sold until 1 October 2009.
Each packet of tobacco products must carry:
One of the following general warnings (in both the Irish and English languages) which must cover at least 32% of the external side.
Toradh caithimh tobac – bás – Smoking kills
Déanann caitheamh tobac díobháil thromchúiseach duit agus do na daoine mórthimpeall ort – Smoking seriously harms you and others around you
and one of the following additional warnings (in both the Irish and English languages) which must cover at least 45% of the external side.
Giorrú saoil tobac a chaitheamh – Smokers die younger
Nuair a chaitear tobac, tachtar na hartairí agus is é cúis le taomanna croí agus strócanna – Smoking clogs the arteries and causes heart attacks and strokes
Caitheamh tobac is cúis le hailse scamhóg mharfach – Smoking causes fatal lung cancer
Má chaitheann tú tobac le linn toirchis, déantar díobháil don leanbán – Smoking when pregnant harms your baby
Cosain leanaí: ná cuir iallach orthu do chuid deataigh an análú – Protect children: don't make them breathe your smoke
Féadann do dhochtúir nó do chógaiseoir cabhrú leat éirí as caitheamh tobac Your doctor or your pharmacist can help you stop smoking
Is éasca a bheith tugtha do chaitheamh tobac, ná tosaigh leis – Smoking is highly addictive, don't start
Má éiríonn tú as tobac a chaitheamh laghdaítear an riosca de ghalair mharfacha chroí agus scamhóg – Stopping smoking reduces the risk of fatal heart and lung diseases
Féadann caitheamh tobac bheith ina chúis le bás mall pianmhar – Smoking can cause a slow and painful death
Faigh cúnamh chun éirí as caitheamh tobac: Íosghlao Stoplíne 1850 201 203 – Get help to stop smoking: Callsave Quitline 1850 201 203
Féadfaidh caitheamh tobac imshruthúfola a laghdú agus bheith ina chúis le héagumas – Smoking may reduce the blood flow and cause impotence
Caitheamh tobac is cúis le críonadh craicinn – Smoking causes ageing of the skin
Féadann caitheamh tobac dochar a dhéanamh don speirm agus laghdaíonn sé torthúlacht – Smoking can damage the sperm and decreases fertility
Cuimsíonn deatach beinséin, nítreasaimíní, formaildéad agus ciainíd hidrigine – Smoke contains benzene, nitrosamines, formaldehyde and hydrogen cyanide
In the case of Smokeless Tobacco Products, only the following warning must be displayed:
Féadann an táirge tobac seo dochar a dhéanamh do shláinte agus is táirge andúile é – This tobacco product can damage your health and is addictive
Italy
/ (Smoking kills / Smoking can kill.)
(Smoking heavily damages you and those around you.)
(Smokers die younger.)
(Smoking clogs arteries and causes heart attacks and strokes.)
(Smoking causes deadly lung cancer.)
(Smoking during pregnancy harms your baby.)
(Protect children, don't smoke in their presence.)
(A doctor or pharmacist can help you quit smoking.)
(Specialists in the medical sector can help you quit smoking.)
(Smoking is highly addictive, don't start.)
(Quitting smoking reduces the risk of deadly cardiovascular and lung diseases.)
(Smoking can cause a long and painful death.)
(Smoking causes oral cavities and cancer.)
(Get help to quit smoking.)
(Smoking may reduce blood circulation and causes impotence.)
(Smoking ages the skin.)
(Smoking may damage sperm and diminishes fertility.)
(Smoke contains benzene, nitrosamines, formaldehyde and hydrocyanic acid.)
(Smoking can lead to blindness.)
Other text is sometimes placed in the packets; for example, some packets contain leaflets which have all the above warnings written on them, with more detailed explanations and reasons to give up, and advice from Philip Morris.
Latvia
(Smoking causes 9 out of 10 lung cancers )
(Smoking causes mouth and throat cancer)
(Smoking damages your lungs)
(Smoking causes heart attacks)
(Smoking causes strokes and disability)
(Smoking clogs your arteries )
(Smoking increases the risk of blindness )
(Smoking can cause teeth damages and illnesses of gums)
(Smoking can kill your unborn child )
(Your smoke harms your children, family and friends )
(Smokers' children are more likely to start smoking)
( Quit smoking now – stay alive for those close to you)
(Smoking reduces fertility)
(Smoking increases the risk of impotence)
Lithuania
General warning:
or
Malta
– (Warning from the Health Department – Danger:)
– (Smoking kills)
– (Smokers die younger)
– (Smoking clogs the arteries and causes heart attacks and strokes)
– (Smoking causes fatal lung cancers)
– (Smoking when pregnant harms your baby)
– (Protect children: don't make them breathe your smoke)
– (Your doctor and your pharmacist can help you stop smoking)
– (Smoking is highly addictive, don't start)
– (Stopping smoking reduces the risk of fatal heart and lung diseases)
– (Smoking can cause a slow and painful death)
– 21231247 – (Get help to stop smoking – 21231247)
– (Smoking may reduce the blood flow and causes impotence)
– (Smoking causes aging of the skin)
– (Smoking can damage the sperm and decrease fertility)
– (Smokes contains benzene, nitrosamines, formaldehyde and hydrogen cyanide)
Netherlands
(Quit smoking, stay alive for your family and friends)
(Smoking is deadly)
(Smoking causes impotence)
(Smoking causes deadly lung cancer)
(Tobacco smoke contains benzene, nitrosamines, formaldehyde and hydrogencyanide)
(Your physician or pharmacist can help you to quit smoking)
(Smokers die younger)
(Smoking causes clogging of the blood vessels, heart attacks and strokes)
(Smoking during pregnancy harms your baby)
(Smoking can kill your unborn child)
(Protect children: don't let them inhale your smoke)
(Smoking is very addictive; prevent yourself from starting)
(Quitting smoking reduces the risk of fatal heart and lung diseases)
(Smoking may result in a slow, painful death)
(Smoking may reduce the blood flow and causes impotence)
(Smoking ages your skin)
(Smoking can damage the sperm and reduces fertility)
(Smoking causes serious damage to you and those around you)
(Your physician or pharmacist can help you to quit smoking, call 0800-555532340 now.)
Poland
Front of packaging (covers 30% of surface):
or
There are also warnings on the back of every packet:
Palacze tytoniu umierają młodziej (Smokers die younger)
Dzieci palaczy częściej zostają palaczami (Children of smokers become smokers by themselves more often)
Palenie tytoniu zamyka naczynia krwionośne i jest przyczyną zawałów serca i udarów mózgu (Smoking causes clogging of the blood vessels, heart attacks and strokes)
Palenie tytoniu powoduje śmiertelnego raka płuc (Smoking causes fatal lung cancer)
Palenie tytoniu w czasie ciąży szkodzi Twojemu dziecku (Smoking while pregnant harms your baby)
Chrońcie dzieci – nie zmuszajcie ich do wdychania dymu tytoniowego (Protect children: don't let them breath your smoke)
Twój lekarz lub farmaceuta pomoże Ci rzucić palenie (Your doctor or your pharmacist can help you quit smoking)
Palenie tytoniu silnie uzależnia – nie zaczynaj palić (Smoking is highly addictive; do not start smoking)
Zaprzestanie palenia zmniejsza ryzyko groźnych chorób serca i płuc (Stopping smoking reduces the risk of serious heart and lung disease)
Palenie tytoniu może spowodować powolną i bolesną śmierć (Smoking can cause a slow and painful death)
Dzwoniąc pod nr telefonu 0801108108, uzyskasz pomoc w rzuceniu palenia (Get help to quit smoking by calling 0801108108)
Palenie tytoniu może zmniejszyć przepływ krwi i powodować impotencję (Smoking can reduce blood flow and cause impotence)
Palenie tytoniu przyśpiesza starzenie się skóry (Smoking accelerates skin aging)
Palenie tytoniu może uszkodzić nasienie i zmniejszać płodność (Smoking can damage sperm and reduce fertility)
Dym tytoniowy zawiera benzen, nitrozoaminy, formaldehyd i cyjanowodór (Tobacco smoke contains benzene, nitrosamines, formaldehyde and hydrogen cyanide)
Portugal
(Smoking kills)
(Smoking causes deadly lung cancer)
(Smoking causes serious addiction. Don't start smoking.)
(Smoking causes skin aging)
(Smoking seriously harms your health and the health of those around you)
(If you're pregnant: Smoking harms your child's health)
(Smokers die prematurely)
(Smoking clogs your arteries and causes heart attacks and strokes)
(Smoking might reduce blood flow and causes impotence)
(Quitting reduces the risks of deadly cardiovascular and pulmonar diseases)
Romania
General warning (on the front of cigarette packages, covering at least 40% of the area):
(Smoking kills)
(Smoking can kill)
(Smoking seriously harms you and those around);
Additional warnings (on the back of cigarette packages, covering at least 50% of the area):
(Smokers die younger.)
(Smoking clogs the arteries and causes heart attacks and strokes)
(Smoking causes lung cancer, which is lethal.)
(Smoking when pregnant harms your baby.)
(Protect children: don't let them breathe your smoke!)
(Your doctor or pharmacist can help you quit smoking)
(Smoking is addictive, don't start smoking!)
(Stopping smoking reduces the risk of fatal heart and lung diseases)
(Smoking can cause a slow and painful death.)
(Get help to stop smoking: telephone/postal address/Internet address/consult your doctor/pharmacist...)
(Smoking reduces blood circulation and causes impotence)
(Smoking causes skin aging.)
(Smoking can affect sperm quality and decreases fertility.)
(Cigarette smoke contains benzene, nitrosamines, formaldehyde and hydrogen cyanide.)
Slovenia
Front of packaging (covers 30% of surface)
or
Rear of packaging (covers 40% of surface)
(Smokers die younger.)
(Smoking clogs arteries and causes heart attacks and strokes.)
(Smoking causes fatal lung cancer.)
(Smoking during pregnancy harms your child.)
(Protect your children from breathing your cigarette smoke.)
(Your doctor or pharmacist can help you quit smoking.)
(Smoking is highly addictive, don't start.)
(Quitting smoking reduces the risk of fatal heart and lung diseases.)
(Smoking can result in a slow and painful death.)
(Seek help to quit smoking: consult your doctor.)
(Smoking can reduce blood circulation and cause impotence.)
(Smoking causes ageing of the skin.)
(Smoking damages sperm and reduces fertility.)
)
Spain
In Spain, cigarette packages are preceded by warnings on both sides of the package marked "Las Autoridades Sanitarias advierten" (Health authorities warn), written in black and white above the black part of the standard warning.
or
Front of cigarette packages
(Smoking can kill) (changed in 2010 to "Fumar mata" <Smoking kills>)
(Smoking seriously harms to your health and that of others)
Back of cigarette packages
(Smoking shortens [your] life)
(Smoking causes fatal lung cancer)
(Tobacco is very addictive, do not start)
(Smoking clogs the arteries and causes heart disease and stroke)
(Smoking causes skin aging)
(Help to stop smoking: consult your doctor or pharmacist)
(Smoking may reduce blood flow and causes impotence)
Sweden
General warnings on all Swedish cigarette packagings have been in force since 1977.
Front of cigarette packages
(Smoking kills.)
(Tobacco causes serious harm to your health.)
(Smoking while pregnant may harm your fetus.)
(Smoking can lead to a slow and painful death.)
(Smoking can impair the blood flow and causes impotence.)
(Smoking seriously hurts you and people around you.)
(Smoke contains benzene, nitrosamines, formaldehyde and hydrogen cyanide.)
(Protect the children. Don't let them inhale your tobacco smoke.)
Back of cigarette packages
(Smoking may damage the sperm and reduce fertility.)
(Smoking is very addictive. Do not start smoking.)
Rear side of snus packaging
(This tobacco product might cause harm to your health and is addictive.)
Georgia
General warning:
Ghana
Ghanaian warnings are compliant with the EU's legislations, as follows:
Packaging 1 (same as in the newer UK packaging):
Smoking seriously harms you and others around you
Stopping smoking reduces the risk of fatal heart and lung diseases
Packaging 2 (same as in the older UK packaging):
Smoking causes cancer
Smoking damages the health of those around you
Packaging 3 (same as in the older UK packaging):
Smoking causes fatal diseases
Smokers die younger
Honduras
In Honduras, a variety of warnings with graphic, disturbing images of tobacco-related harms (including a lung cancer and throat cancer) are placed prominently on cigarette packages.
Hong Kong
Under Hong Kong Law, Chap 371B Smoking (Public Health) (Notices) Order, packaging must indicate the amount of nicotine and tar that is present in cigarette boxes in addition to graphics depicting different health problems caused by smoking in the size and ratio as prescribed by law. The warnings are to be published in both official languages, Traditional Chinese and English.
Every warning begins with the phrase '/HKSAR GOVERNMENT WARNING' and then one of the following in all caps:
/Smoking causes lung cancer
/Smoking kills
/Smoking harms your family
/Smoking causes peripheral vascular diseases
/Smoking may cause impotence
/Smoking can accelerate aging of the skin
In addition, any print advertisement must give minimum 85% coverage of the following warnings:
HKSAR GOVERNMENT HEALTH WARNING
January - February SMOKING KILLS
March - April SMOKING CAUSES CANCER
May - June SMOKING CAUSES HEART DISEASE
July - August SMOKING CAUSES LUNG CANCER
September - October SMOKING CAUSES RESPIRATORY DISEASES
November - December SMOKING HARMS YOUR CHILDREN
In 2018, a new batch of warnings were introduced, consisting of the following warnings that cover 85% of packs:
Iceland
All cigarette packets and other tobacco packaging in Iceland must include warnings in the same size and format as in the European Union and using the same approved texts in Icelandic.
General warning:
These warnings are also used:
(Your doctor or pharmacist can help you quit smoking)
(Smoking causes cancer)
(Smoking is very harmful to you and those close to you)
(Smoking blocks your arteries and causes coronary artery disease and strokes)
(Smoking causes fatal lung cancer)
(Smoking during pregnancy harms your child)
(Protect children – Don't let them inhale tobacco smoke)
India
Cigarette packets sold in India are required to carry graphical and textual health warnings. The warning must cover at least 85% of the surface of the pack, of which 60% must be pictorial and the remaining 25% contains textual warnings in English, Hindi or any other Indian language.
In 2003, India ratified the World Health Organisation's Framework Convention on Tobacco Control, which includes a recommendation for large, clear health warnings on tobacco packages. However, there was a delay in implementing graphic warning labels.
Until 2008, cigarette packets sold in India were required to carry a written warning on the front of the packet with the text CIGARETTE SMOKING IS INJURIOUS TO HEALTH in English. Paan, gutkha and tobacco packets carried the warning TOBACCO IS INJURIOUS TO HEALTH in Hindi and English. The law later changed. According to the new law, cigarette packets were required to carry pictorial warnings of a skull or scorpion along with the text SMOKING KILLS and TOBACCO CAUSES MOUTH CANCER in both Hindi and English.
The Cigarette and Other Tobacco Products (Packaging and Labelling) Rules 2008 requiring graphic health warnings came into force on 31 May 2008. Under the law, all tobacco products were required to display graphic pictures, such as pictures of diseased lungs, and the text SMOKING KILLS or TOBACCO KILLS in English, covering at least 40% of the front of the pack, and retailers must display the cigarette packs in such a way that the pictures on pack are clearly visible. In January 2012, controversy arose when it was discovered that an image of former English footballer John Terry was used on a warning label.
On 15 October 2014, Union Health Minister Harsh Vardhan announced that only 15% of the surface of a pack of cigarettes could contain branding, and that the rest must be used for graphic and text health warnings. The Union Ministry of Health amended the Cigarettes and Other Tobacco Products (Packaging and Labelling) Rules, 2008 to enforce the changes effective from 1 April 2015.
However, the government decision to increase pictorial warnings on tobacco packets from 1 April was put on hold indefinitely, following the recommendations of a Parliamentary committee, which reportedly did not speak to health experts but only to tobacco lobby representatives. On 5 April 2016, the health ministry ordered government agencies to enforce this new rule.
Following the intervention by the Parliamentary committee, NGO Health of Millions, represented by Prashant Bhushan, filed a petition in the Supreme Court of India, which asked the government to stop selling of loose cigarettes and publish bigger health warnings on tobacco packs.
Indonesia
In Indonesia, tobacco warnings are not just placed on packages but also on cigarette advertisements, which are not banned in some countries including Indonesia.
January 1980–December 1999
January 2000–December 2013
With the enforcement of Indonesian Government Regulation No. 19 (2000), a new warning was implemented:
The last recorded usage of this warning in TV advertisements was an Esse Mild advertisement from late February 2014.
December 2013–December 2018
With the enforcement of the Indonesian Government Regulation No. 109 (2012), all tobacco products/cigarette packaging and advertisement should include warning images and age restriction (18+). Graphic warnings must cover 40% of cigarette packages. After the introduction of graphic images in Indonesian cigarette packaging, the branding of cigarettes as "light", "mild", "filter", etc. is forbidden, except for brands that already use some words above such as L.A. Lights, A Mild or Dunhill Filter. However, the last advertisement to use this warning was a 2021 Djarum Super advertisement, before it subsequently used the 2018 warning.
Other alternatives:
PERINGATAN: MEROKOK SEBABKAN KANKER MULUT (Warning: Smoking causes mouth cancer)
PERINGATAN: MEROKOK SEBABKAN KANKER TENGGOROKAN (Warning: Smoking causes throat cancer)
PERINGATAN: MEROKOK DEKAT ANAK BERBAHAYA BAGI MEREKA (Warning: Smoking endangers children near you)
PERINGATAN: MEROKOK SEBABKAN KANKER PARU-PARU DAN BRONKITIS KRONIS (Warning: Smoking causes lung cancer and chronic bronchitis)
These warnings below appear on the side of cigarette packaging:
DILARANG MENJUAL/MEMBERI PADA ANAK USIA DI BAWAH 18 TAHUN DAN PEREMPUAN HAMIL (Do not sell or give [this product] to children under 18 years old and pregnant women)
Optional: TIDAK ADA BATAS AMAN! MENGANDUNG LEBIH DARI 4.000 ZAT KIMIA BERBAHAYA, 43 ZAT PENYEBAB KANKER (There is no safe limit! Contains more than 4,000 hazardous chemicals and 43 carcinogens)
January 2019–present
After it was revealed that the pictorial warnings used in Indonesia originally came from the 2005 warnings of Thailand, on 31 May 2018, the Ministry of Health launched new pictorial health warnings, of which two depict Indonesian smokers and one depicts a smoker from Venezuela.
Other alternatives:
PERINGATAN: MEROKOK SEBABKAN KANKER MULUT (Warning: Smoking causes mouth cancer)
PERINGATAN: MEROKOK SEBABKAN KANKER PARU (Warning: Smoking causes lung cancer)
PERINGATAN: ROKOK MERENGGUT KEBAHAGIAAN SAYA SATU PERSATU (Warning: One by one, cigarettes took my happiness away)
PERINGATAN: MEROKOK SEBABKAN KANKER TENGGOROKAN (Warning: Smoking causes throat cancer)
LAYANAN BERHENTI MEROKOK: 0800-177-6565 (Smoking quitline: 0800-177-6565)
DILARANG MENJUAL/MEMBERI PADA ANAK USIA DI BAWAH 18 TAHUN DAN PEREMPUAN HAMIL (Do not sell or give [this product] to children under 18 years old and pregnant women) (from January 2019 until August 2024)
DILARANG MENJUAL DAN MEMBERI KEPADA ORANG DI BAWAH 21 TAHUN DAN PEREMPUAN HAMIL (Do not sell and distribute to persons under 21 and pregnant women) (from August 2024)
Iran
In Iran, a variety of warnings with graphic, disturbing images of tobacco-related harms (including lung cancer and mouth cancer) are placed prominently on cigarette packages.
Additionally, many cigarette packs contain a writing under the image which says "ترک سیگار موجب سلامتی و افزایش طول عمرمیشود" and in English it roughly means "quitting cigarettes makes you healthier and increases lifespan".
Japan
In 1972, Japan became the first country in Asia to display a general warning on cigarette packages.
Prior to 2005, there was only one warning on all Japanese cigarette packages.
(For the good of your health, be careful not to smoke too much) (1972–1989)
(Be careful not to smoke too much, as there is a risk of damaging your health) (1990–2005)
Since 2005, more than one general warning is printed on cigarette packaging.
On the front of cigarette packages:
(Smoking is a cause of lung cancer. According to epidemiological estimates, smokers are about two to four times more likely than non-smokers to die of lung cancer.)
(Smoking increases risk of myocardial infarctions. According to epidemiological estimates, smokers are about 1.7 times more likely than non-smokers to die of a heart attack.)
(Smoking increases risk of strokes. According to epidemiological estimates, smokers are about 1.7 times more likely than non-smokers to die of a stroke.)
(Smoking can aggravate the symptoms of emphysema.)
On the back of cigarette packages:
(Smoking during pregnancy is a cause of premature births and impaired fetal growth. According to epidemiological estimates, pregnant women who smoke have almost double the risk of low birth weight and three times the risk of premature births than pregnant women who do not smoke. (For more information, please visit the Ministry of Health home page at www.mhlw.go.jp/topics/tobacco/main.html.))
(Tobacco smoke adversely affects the health of people around you, especially infants, children and the elderly. When smoking, be careful not to annoy others.)
(The degree may differ from person to person, but nicotine [in cigarettes] causes addiction to smoking.)
(Smoking while underage heightens the addiction and damage to health caused by cigarettes. Never smoke, even if encouraged to by those around you.)
Laos
In Laos, a variety of warnings with graphic, disturbing images of tobacco-related harms (including mouth cancer and rotting teeth) are placed prominently on cigarette packages.
Malaysia
In Malaysia, general warning as a mandatory on all Malaysian cigarette packaging are in force since June 1976.
(Warning from the Government of Malaysia: Smoking endangers health)
Starting 1 June 2009, the Malaysian government has decided to place graphic images on the cigarette packs to show the adverse long-term effects of excessive smoking, replacing the general warning with text describing the graphic images printed in Malay (front) and English (back) explaining:
"Amaran: Rokok penyebab ..."
"Warning: Cigarettes cause ..."
Graphic warning messages must consist 40% of the front of cigarette packages and 60% in the back. After the introduction of graphic images in Malaysian cigarette packaging, the branding of cigarettes as "light", "mild", etc. is forbidden.
Maldives
In the Maldives, products containing tobacco are required by law to have (in Dhivehi):
At the front and back:
A health warning eg. Smoking gives you a painful death ()
A cessation message eg. Stop quickly! ()
A graphic image eg. cut open body showing lung cancer
Description of the image
On the sides:
Explanatory message of complications caused by tobacco eg. Tobacco contains 250 poisonous chemicals. These poisons damage vital organs of the body, causing cancer, stroke, lung damage, and other such painful illnesses. ()
A message Get help from a health professional to save yourself! ()
Mexico
Since 2010, cigarette packs in Mexico must contain health warnings and graphic images. By law, 30% of the pack's front, 100% of the pack's rear and 100% of one lateral must consist on images and warnings. The Secretariat of Health issues new warnings and images every six months. Images have included a dead rat, a partial mastectomy, a laryngectomy, a dead human fetus surrounded by cigarette butts, a woman being fed after suffering a stroke and damaged lungs, amongst others.
Warnings include smoking-related diseases and statistics, toxins found in cigarettes and others.
Mexico became the first country to put a warning on cigarette packs that tobacco use could increase the risk of COVID-19 infection.
Moldova
General warning (on the front of cigarette packages, covering at least 30% of the area, Helvetica font):
"Fumatul ucide" (Smoking kills) or
"Fumatul dăunează grav sănătăţii dumneavoastră şi a celor din jur" (Smoking seriously harms you and those around);
Additional warnings (on the back of cigarette packages, covering at least 40% of the area, Helvetica font):
"Fumătorii mor mai tineri" (smokers die younger);
"Fumatul blochează arterele şi provoacă infarct miocardic şi accident vascular cerebral" (Smoking clogs the arteries and causes heart attacks and strokes);
"Fumatul conduce la moarte de cancer pulmonar" (smoking causes death from lung cancer);
"Fumatul în timpul sarcinii dăunează copilului dumneavoastră" (Smoking while pregnant harm your baby);
"Protejaţi copiii dumneavoastră de inspirarea fumului de ţigaretă" (Protect your children from breathing in the cigarette smoke);
"Psihologul, profesorul sau medicul vă poate ajuta să renunţaţi la fumat" (Psychologists, professors and doctors can help you quit smoking);
"Fumatul creează dependenţă rapidă, nu încercaţi să fumaţi" (Smoking becomes addictive fast, try not to smoke);
"Abandonarea fumatului reduce riscul de îmbolnăviri cardiace sau pulmonare fatale" (Quitting smoking reduces the risk of fatal heart and lung diseases);
"Fumatul poate provoca o moarte lentă şi dureroasă" (Smoking can cause a slow and painful death);
"Fumatul reduce circulaţia sîngelui şi provoacă impotenţă" (Smoking reduces blood circulation and increases impotency);
"Fumatul provoacă îmbolnăvirea tenului (pielei)" (Smoking causes skin diseases);
"Fumatul creează grave disfuncţii sexuale" (Smoking causes serious sexual dysfunction);
Regulated by "Lege cu privire la tutun şi la articolele din tutun" (Law on tobacco and tobacco articles) nr. 278-XVI from 14.12.2007 enabled at 07.03.2008
There is no such rule in Transnistria, where cigarette packages have variable warning labels depending on where they come from.
New Zealand
The first health warnings appeared on cigarette packets in New Zealand in 1974. Warning images accompanying text have been required to appear on each packet since 28 February 2008. New regulations were made on 14 March 2018 which provided for larger warnings and a new schedule of images and messages.
By law, 75% of a pack's front and 100% of its rear must consist of warning messages. Images include gangrenous toes, rotting teeth and gums, diseased lungs and smoking-damaged hearts. Cigarette packets also carry the New Zealand Quitline logo and phone number and other information about quitting smoking.
In total, there are 15 different warnings. A full list with pictures is available at the New Zealand Ministry of Health's website. Warning messages are rotated annually. The following is a list of the warnings in English and Māori.
Smoking causes heart attacks, KA PĀ MAI NGĀ MANAWA-HĒ I TE KAI PAIPA
Smoking causes over 80% of lung cancers, NEKE ATU I TE 80% O NGĀ MATE PUKUPUKU KI NGĀ PŪKAHUKAHU I AHU MAI I TE KAI PAIPA
Smoking harms your baby before it is born, KA TŪKINOHIA TŌ PĒPI I TO KŌPŪ I TE KAI PAIPA
Your smoking harms others, KA TŪKINOHIA ĒTAHI ATU I Ō MAHI KAI PAIPA
Smoking is a major cause of stroke, KA PIKI AKE I TE KAI PAIPA TŌ TŪPONO KI TE IKURA RORO
Smoking damages your blood vessels, KA TŪKINOHIA Ō IA TOTO I TE KAI PAIPA
Smoking is not attractive, KA ANUANU KOE I TE KAI PAIPA
Smoking causes lung cancer, KA PĀ MAI TE MATE PUKUPUKU KI NGĀ PŪKAHUKAHU I TE KAI PAIPA
Smoking when pregnant harms your baby, KA TŪKINOHIA TŌ PĒPI I TE KAI PAIPA I A KOE E HAPŪ ANA
Your smoking harms children, KA TŪKINOHIA NGĀ TAMARIKI I Ō MAHI KAI PAIPA
Quit before it is too late, ME WHAKAMUTU KEI RIRO KOE
Smoking causes gum disease and stinking breath, KA PĀ TE MATE PŪNIHO, KA HAUNGA TŌ HĀ I TE KAI PAIPA
Nigeria
Six warnings existed prior to 2013:
Smoking is addictive
Smoking damages lungs
Smoking can kill
Smoking can cause cancer
Smoking can damage the fetus
From 2013 onwards, the general warning is: The Federal Ministry of Health warns that smokers are liable to die young.
North Korea
North Korea signed the WHO Framework Convention on Tobacco Control on 17 June 2003 and ratified it on 27 April 2005. Tobacco packaging warning messages are required on all types of packaging, but their appearance is not regulated in any way. They are usually printed in small print on the side of the package and only state that smoking is harmful to health. However, the descriptions must state the nicotine and tar content, must not be misleading and do need to be approved by local authorities. Graphic warning images that are now common worldwide have never appeared on packaging in North Korea.
Norway
Norway has had general warnings on cigarette packets since 1975. Norway's warnings of today were introduced in 2003 and are in line with the European Union's legislation, as Norway is an EEA member:
On the front of cigarette and cigar packages, covering about 30% of the area:
(Smoking kills)
(Smoking is very harmful to you and your surroundings)
On the back of cigarette and cigar packages, covering about 45% of the area:
(Smoking causes fatal lung cancer)
(If you stop smoking, you will reduce the risk of fatal heart and lung diseases)
(Smoking causes early ageing of the skin)
(Smoking may reduce the blood flow and cause impotence)
(Smoking can cause a slow and painful death)
(Smoking can reduce sperm quality and decrease fertility)
(Protect children against smoke, don't let them inhale your smoke)
(Smoking is highly addictive: Don't start smoking)
(Smoking clogs the arteries and causes heart attacks and strokes)
(Your doctor or your pharmacy can help you stop smoking)
(Get help to stop smoking – call the Quitline: 800 400 85)
(Smoking lowers life expectancy)
(Smoking during pregnancy harms the child)
(Smoke contains benzene, nitrosamines, formaldehyde and hydrogen cyanide)
Tobacco products like snus and chewing tobacco have the following warning printed on them:
(This tobacco product may be a health hazard and is addictive)
Pakistan
All cigarettes are required by Statutory Order 1219(I)/2008 dated 25 September 2008, published in the Gazette of Pakistan dated 24 November 2008, to carry rotating health warnings from 1 July 2009.
Each health warning is printed for a period of 6 months, covering at least 30% on both sides of the packet and must be printed in Urdu at the front and English at the back. The warnings in English currently in use are:
Protect children, do not let them breathe your smoke – Ministry of Health
Smoking causes mouth and throat cancer – Ministry of Health
Quit smoking and live a longer life – Ministry of Health
Smoking severely harms you and the people around you – Ministry of Health
Panama
In Panama, a variety of warnings with graphic, disturbing images of tobacco-related harms (including throat cancer and lung cancer) are placed prominently on cigarette packages.
Paraguay
In Paraguay, a variety of warnings with graphic, disturbing images of tobacco-related harms (including impotence and heart attack) are placed prominently on cigarette packages.
Peru
In Peru, a variety of warnings with graphic, disturbing images of tobacco-related harms (including abortions and asthma) are placed prominently on cigarette packages.
Philippines
All cigarette packaging sold in the Philippines are required to display a government warning label. The warnings include:
Government Warning: Cigarette smoking is dangerous to your health.
Government Warning: Cigarettes are addictive.
Government Warning: Tobacco smoke can harm your children.
Government Warning: Smoking kills.
In July 2014, President Benigno Aquino III signed the Republic Act 10643, or "An Act to Effectively Instill Health Consciousness through Graphic Health Warnings on Tobacco Products", more known as the "Graphic Health Warning Act." This law requires tobacco product packaging to display pictures of the ill effects of smoking, occupying the bottom half of the display area in both front and the back side of the packaging. On 3 March 2016, Department of Health (DOH) secretary Janette Garin started the implementation of Republic Act 10643, requiring tobacco manufacturers to include graphic health warnings on newer cigarette packaging.
With the Graphic Health Warning Act implemented, graphic health warnings are used on all newer cigarette packages and older packages using text-only warnings are required to be replaced by newer ones incorporating graphic warnings. The 12 new warnings, showing photos of negative effects of smoking, like mouth cancer, impotence and gangrene are rotated every two years, and on 3 November 2016, all cigarette packaging without graphic health warning messages are banned from sale. Labeling of cigarettes with "light" or "mild" is also forbidden by the Graphic Health Warning Act.
Russia
Warning messages on Russian cigarette packets were revised in 2013, falling in line with European Union standards.
12 different variants are used.
Serbia
The warning messages on Serbian cigarette packets are visually similar to what is used in European Union countries, but the texts used in Serbia are not translated from EU-approved texts.
Singapore
Singapore used blunt, straight-to-the-point messages such as "Smoking causes lung cancer" as text warnings on cigarette packets. They were later replaced by graphic warnings in August 2004, with gory pictures and the following messages:
Smoking causes a slow and painful death
Smoking harms your family
Tobacco smoke can kill babies
Smoking causes strokes
Smoking causes lung cancer
Smoking causes mouth diseases
In 2016, the images and warnings were revised, with images focusing mostly on damaged organs. The following warnings show what is printed nowadays.
Smoking causes mouth diseases
Smoking can cause a slow and painful death
Smoking causes lung cancer
Smoking causes gangrene
Smoking causes neck cancer
Smoking harms your family
Smoking causes 92% of oral cancers
From 1 January 2009, people possessing cigarettes without the SDPC (Singapore Duty Paid Cigarettes) label will be committing an offence under the Customs and GST Acts. The law was passed to distinguish non-duty paid, contraband cigarettes from duty-paid ones.
Switzerland
Switzerland has four official languages, but only has warning messages in three languages. The fourth language, Romansh, is only spoken by 0.5% of the population and those persons typically also speak either German or Italian. The three warning messages below, all meaning "Smoking kills", are posted on cigarette packs, cartons and advertisements such as outdoor billboards and posters:
Fumer tue.
Rauchen tötet.
Il fumo uccide.
Somalia
A small warning, in Somali and English, is printed on Somali cigarette packages.
South Africa
In South Africa, the Tobacco Products Control Act, 1993 and its amendments (1999, 2007, 2009), stipulate that a warning related to the harmful effects (health, social, or economic) of tobacco smoking, or the beneficial effects of cessation, must be placed prominently on tobacco products covering 15% of the obverse, 25% of the reverse and 20% of the sides of packs.
According to the draft Control of Tobacco Products and Electronic Delivery Systems Bill, 2018, new legislation, once enacted, will require uniform, plain-colored packaging (branding and logos prohibited) containing the brand and product name in a standard typeface and color, a warning related to the harmful effects of tobacco smoking, or beneficial effects of cessation, and a graphic image of tobacco-related harm.
South Korea
In South Korea, general warnings on cigarette packaging have been used since 1976. The warning messages used since then have been:
From 1976 to November 1989: (For your health, please refrain from smoking too much)
From December 1989 to 1996: (Smoking may cause lung cancer and it is especially dangerous for teenagers and pregnant women)
From 1996 to March 2005:
Front: (Smoking causes lung cancer and other diseases and it is especially dangerous for teenagers and pregnant women)
Back: (It is illegal to sell cigarettes to people under 19) and additionally, (You can be healthy and live longer if you quit), (Smoking also causes paralysis and heart diseases), (Smoking also damages your beloved children), (Smoking damages others)
From April 2005 to April 2007:
Front: 건강을 해치는 담배 그래도 피우시겠습니까? (Smoking damages your health. Do you still want to smoke?)
Back: 19세 미만 청소년에게 판매할 수 없습니다 (It is illegal to sell cigarettes to people under 19) and additionally, 금연하면 건강해지고 장수할 수 있습니다 (You can be healthy and live longer if you quit), 흡연은 중풍과 심장병도 일으킵니다 (Smoking also causes paralysis and heart diseases), 흡연은 사랑하는 자녀의 건강도 해칩니다 (Smoking also damages your beloved children), 당신이 흡연하면 다른 사람의 건강도 해칩니다 (Smoking hurts others)
From April 2007 to April 2009
Front, 흡연은 폐암 등 각종 질병의 원인이 되며, 특히 임신부와 청소년의 건강에 해롭습니다 (Smoking causes lung cancer and other diseases and it is especially dangerous for teenagers and pregnant women)
Back: 19세 미만 청소년에게 판매 금지! 당신 자녀의 건강을 해칩니다" (It is illegal to sell cigarettes to people under 19! It hurts your children's health)
From April 2009 to April 2011 (a prospectus)
Front: (Smoking damages your health. Once you start smoking, it is very difficult to quit)
Back: (It is illegal to sell cigarettes to people under 19! It hurts your children's health)
From December 2016, 50% of cigarette packages must contain warning elements, of which 30% must be graphic warnings. In addition to the existing warning: (Smoking can be a cause of disease), the following warning will be mandatory: (Smoking can harm others' health)
From 2017, more pictorial warnings were added to cigarette packs.
Sri Lanka
In Sri Lanka, a variety of warnings with graphic, disturbing images of tobacco-related harms (including cancer and heart attack) are placed prominently on cigarette packages.
Taiwan
The warnings in Taiwan are led by the phrase "行政院衛生署警告" (Warning from the Department of Health, Executive Yuan:) and followed by one of the following warnings:
吸菸有害健康: Smoking is hazardous to your health
孕婦吸菸易導致胎兒早產及體重不足: Smoking during pregnancy can cause premature death and underweight birth
抽菸會導致肺癌﹑心臟病﹑氣腫及與懷孕有關的問題: Smoking can cause lung cancer, heart diseases, emphysema and pregnancy-related problems
吸菸害人害己: Smoking hurts yourself and others
懷孕婦女吸菸可能傷害胎兒，導致早產及體重不足: Smoking during pregnancy might damage the fetus and can cause premature death and underweight birth
戒菸可減少健康的危害: Quitting smoking can reduce health risks (no longer used)
The images and warnings were revised in 2014, after the Department of Health was reorganised into the Ministry of Health and Welfare. The following warnings show what is printed since 1 June 2014.
吸菸導致皮膚老化: Smoking causes ageing of the skin
菸癮困你一生: Tobacco addiction traps your life
吸菸會導致性功能障礙: Smoking causes sexual dysfunctions
菸害導致胎兒異常及早產: Smoking causes birth defects and premature birth
不吸菸，你可以擁有更多: You can have more if you quit smoking
二手菸引發兒童肺炎、中耳炎、癌症: Second hand smoking causes pneumonia, otitis media and cancer in children
吸菸影響口腔衛生: Smoking affects oral hygiene
吸菸引發自己與家人中風與心臟病: Smoking makes you and your family suffer strokes and heart diseases
Warnings of any version are accompanied with "戒煙專線: 0800-636363" (Smoking Quitline: 0800–636363).
Thailand
In Thailand, a variety of warnings with graphic, disturbing images of tobacco-related harms (including a tracheotomy and rotting teeth) are placed prominently on cigarette packages. A recent study showed that the warnings made Thai smokers think more often about the health risks of smoking and about quitting smoking.
Thailand introduced plain packaging in 2020.
Turkey
Front of packaging (covers 65% of surface)
or
Back of packaging (covers 40% of surface)
(Smokers die younger)
(Smoking clogs the arteries and causes heart attacks and paralysis.)
(Smoking causes lethal lung cancer)
(Smoking while pregnant will harm the baby)
(Protect your children, don't let them breathe your smoke.)
(Health agencies can help you quit smoking)
(Smoking is highly addictive, don't start)
(Stopping smoking reduces the risk of fatal heart and lung diseases)
(Smoking can cause a slow and painful death)
(To quit smoking ask for help from your doctor and ...)
(Smoking will slow the blood flow and cause impotence)
(Smoking causes early ageing of the skin)
(Smoking can damage the sperm and decreases fertility)
(Cigarette smoke contains carcinogens such as benzene, nitrosamines, formaldehyde and hydrogen cyanide.)
Ukraine
The warning messages on Ukrainian cigarette packets are also visually similar to those in European Union countries:
United Kingdom
In 1971, tobacco companies printed on the left side of cigarette packets an official warning: "Warning by H.M. Government – Smoking can harm your health", followed by the phrase "Health Department's Chief Medical Officers", issuers of the warning.
In 1991, the EU tightened laws on tobacco warnings. Thus, the message "Tobacco seriously damages health" was printed on the front of all tobacco packs. An additional warning was also printed on the reverse of cigarette packs.
In 2003, new EU regulations required one of the following general warnings must be displayed, covering at least 30% of the surface of the pack:
Smoking kills (- quit now)
Smoking seriously harms you and others around you
Additionally, one of the following additional warnings must be displayed, covering at least 40% of the surface of the pack:
Smokers die younger
Smoking clogs the arteries and causes heart attacks and strokes
Smoking causes fatal lung cancer
Smoking when pregnant harms your baby
Protect children: don't make them breathe your smoke
Your doctor or your pharmacist can help you stop smoking
Smoking is highly addictive, don't start
Stopping smoking reduces the risk of fatal heart and lung diseases
Smoking can cause a slow and painful death
Get help to stop smoking: [telephone]/[postal address]/[internet address]/consult your doctor/pharmacist
Smoking may reduce the blood flow and cause impotence
Smoking causes ageing of the skin
Smoking can damage the sperm and decreases fertility
Smoke contains benzene, nitrosamines, formaldehyde and hydrogen cyanide
From October 2008, all cigarette products manufactured must carry picture warnings in the reverse. Every pack must have one of these warnings by October 2009.
Plain packaging, including prominent and standardised health warnings and minimal manufacturer information, became compulsory for all cigarette and hand-rolling tobacco packs manufactured after May 2016 and sold after May 2017.
United States
In 1966, the United States became the first nation in the world to require a health warning on cigarette packages.
In 1973, the assistant director of Research at R.J. Reynolds Tobacco Company wrote an internal memorandum regarding new brands of cigarettes for the youth market. He observed that, "psychologically, at eighteen, one is immortal" and theorized that "the desire to be daring is part of the motivation to start smoking." He stated, "in this sense the label on the package is a plus."
In 1999, Philip Morris USA purchased three brands of cigarettes from Liggett Group Inc. The brands were: Chesterfield, L&M, and Lark. At the time Philip Morris purchased the brands from Liggett, the packaging for those cigarettes included the statement "Smoking is Addictive". After Philip Morris acquired the three Liggett brands, it removed the statement from the packages.
Though the United States started the trend of labeling cigarette packages with warnings, today the country has one of the least restrictive labelling requirements on their packages. Warnings are usually in small typeface placed along one of the sides of the cigarette packs with colors and fonts that closely resemble the rest of the package, so the warnings essentially are integrated and do not stand out with the rest of the cigarette package.
However, this is subject to change as the Family Smoking Prevention and Tobacco Control Act of 2009 requires color graphics with supplemental text that depicts the negative consequences of smoking to cover 50% of the front and rear of each pack. The nine new graphic warning labels were announced by the FDA in June 2011 and were required to appear on packaging by September 2012, though this was delayed by legal challenges.
In August 2011, five tobacco companies filed a lawsuit against the FDA in an effort to reverse the new warning mandate. Tobacco companies claimed that being required to promote government anti-smoking campaigns by placing the new warnings on packaging violates the companies' free speech rights. Additionally, R.J. Reynolds, Lorillard, Commonwealth Brands Inc., Liggett Group LLC and Santa Fe Natural Tobacco Company Inc. claimed that the graphic labels are an unconstitutional way of forcing tobacco companies to engage in anti-smoking advocacy on the government's behalf. A First Amendment lawyer, Floyd Abrams, represented the tobacco companies in the case, contending that requiring graphic warning labels on a lawful product cannot withstand constitutional scrutiny. The Association of National Advertisers and the American Advertising Federation also filed a brief in the suit, arguing that the labels infringe on commercial free speech and could lead to further government intrusion if left unchallenged.
On 29 February 2012, US District Judge Richard Leon ruled that the labels violate the right to free speech in the First Amendment. However, the following month the US Court of Appeals for the 6th Circuit upheld the majority of the Tobacco Control Act of 2009, including the part requiring graphic warning labels. In April 2013 the Supreme Court declined to hear the appeal to this ruling, allowing the new labels to stand. As the original ruling against the FDA images was not actually reversed, the FDA will again need to go through the process of developing the new warning labels, and the timetable and final product remain unknown. Additionally, rulings of the 6th Circuit are precedential only in the states comprising the 6th Circuit, i.e., Michigan, Ohio, Kentucky, and Tennessee.
In March 2020, the FDA approved a set of 11 new graphic warning labels with images for cigarette packaging, with a deadline of compliance being set to June 18, 2021. The mandate would have required packaging to cover the top 50% of the front and rear panels of packages, as well as at least 20% of the top. Tobacco manufacturers R.J. Reynolds Tobacco Co., Philip Morris USA, ITG Brands LLC and Liggett Group LLC filed a joint motion requesting a preliminary injunction on implementing the labels and a ruling to prohibit enforcement in April 2020. They argued that the new packaging would have been a violation of the First Amendment. In December 2022, U.S. district judge J. Campbell Barker of the Eastern District of Texas ordered the new guidelines to be vacated, arguing the multiple interpretation of images cannot prove neutrality. The deadline was pushed to November 6, 2023. The decision was later appealed and overturned by a U.S. Appeals court who ruled unanimously that the warnings where "factual and uncontroversial" and thus was not in violation of the first amendment. The decision was later appealed again to the U.S. Supreme Court however they declined to hear the case, thus making the new packaging legal. In September 2024 the FDA announced that Enforcement of the new packaging would begin on December 12, 2025.
Cigars
SURGEON GENERAL WARNING: Cigar Smoking Can Cause Cancers of the Mouth And Throat, Even If You Do Not Inhale.
SURGEON GENERAL WARNING: Cigars Are Not A Safe Alternative To Cigarettes.
SURGEON GENERAL WARNING: Tobacco Smoke Increases The Risk of Lung Cancer And Heart Disease, Even in Nonsmokers.
SURGEON GENERAL WARNING: Cigar Smoking Can Cause Lung Cancer And Heart Disease.
SURGEON GENERAL WARNING: Tobacco Use Increases The Risk of Infertility, Stillbirth, And Low Birth Weight.
SURGEON GENERAL WARNING: This Product Contains/Produces Chemicals Known to the State of California To Cause Cancer, And Birth Defects Or Other Reproductive Harm.
Stronger warning labels started to appear in May 2010, but are yet to be officially implemented.
Smokeless tobacco
Effective June 2010, the following labels began to appear on smokeless tobacco products (most of which are chewing tobacco) and their advertisements.
Warning: This product can cause mouth cancer.
Warning: This product can cause gum disease and tooth loss.
Warning: This product is not a safe alternative to cigarettes.
Warning: Smokeless tobacco is addictive.
These warnings are required to comprise 30% of two principal display panels on the packaging; on advertisements, the health warnings must constitute 20% of the total area.
Uruguay
In Uruguay, a variety of warnings with graphic, disturbing images of tobacco-related harms (including lung cancer and mouth cancer) are placed prominently on cigarette packages.
Venezuela
Since 1978 in Venezuela, the only warning in cigarette packs was printed in a very small typeface along one of the sides:
"" (It has been determined that cigarette smoking is harmful to your health – Cigarette Tax Law)
On 24 March 2005, another warning was introduced in every cigarette pack, similar to what was implemented in Brazil: "Este producto contiene alquitrán, nicotina y monóxido de carbono, los cuales son cancerígenos y tóxicos. No existen niveles seguros para el consumo de estas sustancias" ("This product contains tar, nicotine and carbon monoxide, which are carcinogenic and toxic. There are no safe levels for consumption of these substances").
The 1978 warning was not removed, so now every cigarette pack contains both warnings (one on each side).
In addition, since 24 March 2005, as part of the "Venezuela 100% libre de humo" (100% smoke-free Venezuela) campaign, one of the following warnings is randomly printed very prominently, along with a graphical image, occupying 100% of the back of the pack (40% for the text warning and 60% for the image):
(This product is hazardous to your health and is addictive)
(Smoking causes bad breath, tooth decay and mouth cancer)
(Smoking causes lung cancer, coughing, pulmonar emphysema and chronic bronchitis). The picture accompanying this warning is a comparison between a smoker's lung on the left and a healthy lung on the right.
(Smoking causes cardiac infarction. R.I.P. bearer, killed by smoking)
(Smoking while pregnant harms your baby's health)
(Children start smoking when they see adults smoke)
(Smoking cigarettes causes laryngeal cancer)
(Smoking causes impotence in men)
(Cigarette smoke also harms those who don't smoke)
(Take your first step today, quitting smoking is possible)
Curiously, these warnings only appear on cigarette packs and not on other tobacco products (which only use the 1978 warning).
Vietnam
The following warnings appear on Vietnamese cigarette packages since 2013, along with graphic, disturbing images of tobacco-related harms:
(Smoking leads to a slow and painful death)
(Cigarette smoke is harmful to infants and young children)
(Smoking causes heart diseases)
(Smoking causes throat and laryngeal cancer)
(Smoking causes halitosis and damages teeth)
(Smoking causes lung cancer)
References
External links
Tobacco Labelling Resource Centre
Warning: Graphic Cigarette Labels — slideshow by Life magazine
BBC News Online: "Spoof cigarette warnings slammed"
Directive 2001/37/EC of the European Parliament and of the Council of 5 June 2001
UCSF Tobacco Industry Videos Collection
Quit Now, website advertised on Australian packets of cigarettes
Cigarette Package Health Warnings International Status Report – Fourth Edition
Tobacco control
Cigarette packaging
Safety
Warning systems
Health effects of tobacco
Tobacco | Tobacco packaging warning messages | Technology,Engineering | 19,274 |
18,876,510 | https://en.wikipedia.org/wiki/Ministry%20of%20Energy%20%28Israel%29 | The Ministry of Energy () is the Israeli government ministry responsible for energy and water infrastructure. The ministry has changed names several times since its establishment.
The ministerial post was established in 1977, succeeding the position of Development Ministry, which had been scrapped three years earlier.
Names
The Ministry of Energy has been called the following names:
Ministry of Energy and Infrastructure (משרד האנרגיה והתשתיות) – 1977–1996
Ministry of National Infrastructures (משרד התשתיות הלאומיות) – 1996–2011
Ministry of Energy and Water Resources (משרד האנרגיה והמים) – 2011–2013
Ministry of National Infrastructures, Energy and Water (משרד התשתיות הלאומיות, האנרגיה והמים) – 2013–2017
Ministry of Energy (משרד האנרגיה) – 2017–2023
Ministry of Energy and Infrastructure (משרד האנרגיה והתשתיות) – 2023–
List of ministers
Deputy ministers
References
External links
Official website
All Ministers in the Ministry of Energy and Infrastructure Knesset website
Energy
Ministry of Energy
Energy
Israel
1977 establishments in Israel | Ministry of Energy (Israel) | Engineering | 283 |
29,806,465 | https://en.wikipedia.org/wiki/Animal%20models%20of%20depression | Animal models of depression are research tools used to investigate depression and action of antidepressants. They are used as a simulation to investigate the symptomatology and pathophysiology of depressive illness and to screen novel antidepressants. These models provide insights into molecular, genetic, and epigenetic factors associated with depression. Criteria for valid animal models include face, construct, and predictive validity. Endophenotypes, such as anhedonia, behavioral despair, changes in appetite, neuroanatomical alterations, neuroendocrine disturbances, alterations in sleep architecture, and anxiety-related behaviors, are evaluated in these models. Antidepressant screening tests are employed to assess the effects of genetic, pharmacological, or environmental manipulations. Stress models including learned helplessness, chronic mild stress, and social defeat stress simulate the impact of stressors on depression. Early life stress models, psychostimulant withdrawal models, olfactory bulbectomy, and genetically engineered mice contribute to a comprehensive understanding of depression's etiology and potential therapeutic interventions.
Introduction
Depression
Major depressive disorder is commonly called "clinical depression" or "depression." It is a common, long-lasting and diverse psychiatric syndrome that significantly affects a person's thoughts, behavior, feelings and sense of well-being. According to the DSM-5, someone diagnosed with depression should be showing at least five symptoms and they should last two weeks. Depression can include a variety of different symptoms and does not always look the same for everyone. Some of these symptoms may include sadness, anxiousness, emptiness, hopelessness, worry, helplessness, worthlessness, guilt, irritableness, hurt, or restlessness. People experiencing depression may also lose interest in activities that once were pleasurable, experience loss of appetite, overeat, have problems concentrating, remembering details, making decisions, and may contemplate or attempt suicide. Insomnia, excessive sleeping, fatigue, loss of energy, aches, pains, or digestive problems that are resistant to treatment may also be present.
Modeling depression in animals
It is difficult to develop an animal model that perfectly reproduces the symptoms of depression in patients. It is generic that 3 standards may be used to evaluate the reliability of an animal version of depression: the phenomenological or morphological appearances (face validity), a comparable etiology (assemble validity), and healing similarities (predictive validity). Many animals lack self-consciousness, self-reflection, and consideration; moreover, hallmarks of the disorder such as depressed mood, low self-esteem or suicidality are hardly accessible in non-humans. However, depression, as other mental disorders, consists of endophenotypes that can be reproduced independently and evaluated in animals. An ideal animal model offers an opportunity to understand molecular, genetic, and epigenetic factors that may lead to depression. By using animal models, the underlying molecular alterations and the causal relationship between genetic, or environmental, alterations and depression can be examined. This would afford a better insight into pathology of depression because animal models are indispensable for identifying novel therapies for depression.
Endophenotypes in animal model of depression
The following endophenotypes have been described:
Anhedonia: The loss of interest is a core symptom of depression. Anhedonia in rodents can be assessed by sucrose preference or by intracranial self-stimulation.
Behavioral despair: Behavioral despair might be assessed with tests such as the forced-swimming test or the tail suspension test.
Changes in appetite or weight gain: Depression is often associated with changes in appetite or weight gain, which is easily measured in rodents. There was a study done where the experimental group of mice had a suppressed feeding schedule; this resulted in the mice showing depressive-like symptoms.
Neuroanatomy: Depressed subjects display decreased hippocampal volume. Rodents exposed to chronic stress or excess glucocorticoids exhibit similar signs of hippocampal loss of neurons and dendritic atrophy.
Neuroendocrine disturbances: Disturbances of the hypothalamic–pituitary–adrenal axis (HPA) are one of the most consistent symptoms in major depression. The functionality of the HPA can be assessed by dexamethasone suppression test .
Alterations in sleep architecture: Disturbances in the circadian rhythm and especially in the sleep architecture are often observed in depression. In rodents, it is accessible via electroencephalography (EEG).
Anxiety-related behavior: Anxiety is a symptom with high prevalence in depression. Animal models of depression often display altered anxiety-related behavior.
Criteria for valid animal models of depression
An appropriate animal model of human depression should fulfill the following criteria as much as possible: strong phenomenological similarities and similar pathophysiology (face validity), comparable etiology (construct validity), and common treatment (predictive validity). Depression is a heterogeneous disorder and its many symptoms are hard to produce in laboratory animals. When studying depression used in animals originally, symptoms equivalent to odd social behavior and emotion were used to determine if the animal had depression. The question therefore remains whether we can know if the animal is "depressed". They are unable to have the emotions that are associated specifically with humans, like sadness. Few models of depression fully fit these validating criteria, and most models currently used rely on either actions of known antidepressants or responses to stress. It is not necessary for an "ideal" animal model of depression to exhibit all the abnormalities of depression-relevant behaviors, just as not all patients manifest every possible symptom of depression.
Creating models
Research use a number of standardized ways to induce depression-like symptoms in lab animals. The most commonly used type of models are based on stress.
Stress models
Certain types of human depression are precipitated by stressful life events, and vulnerable individuals experiencing these stressors. Consequently, the majority of animal models of depression are based on the exposure to various types of acute or chronic stressors.
Adult stress models
Learned helplessness: The learned helplessness model (LH), one of the well validated animal models, is the best replicated one. The rationale is that exposure to uncontrollable and stressful life events makes people feel like they are losing control, and this sometimes leads to depressive like behaviors. The model is based on the observation that animals also develop deficits in escape, cognitive and rewarded behaviors when they have been subjected to repeated unavoidable and uncontrollable shocks. LH is induced in one day or over several days of repeated inescapable stress by the treating of tail shock or foot shock in shuttle boxes. Helpless behavior is evaluated by analyzing the performance in an active escape test, such as the latency to press a lever or cross a door. An advantage of LH is that the cognitive and other behavioral outcomes seem to be correlated, thus helping to understand the depressive symptomatology in humans. This model can also be generally used to measure the escape performance of mice with different mutations in which target genes of depression may affect the vulnerability to develop a depressive-like state. These excellent face and predictive validities make LH an interesting model to explore the pathophysiology of depression. The biggest disadvantage of LH is it requires very strong stressors to induce the behavioral phenotypes which does raise ethical problems. Also, most of the symptoms do not persist long enough following cessation of the uncontrollable shock.
Chronic mild stress: The chronic mild stress (CMS) model is probably the most valid animal model of depression. It aims to model a chronic depressive-like state that develops gradually over time in response to stress, and they can provide more natural induction. CMS involves the exposure of animals to a series of mild and unpredictable stressors (periods of food and water deprivation, small temperature reductions, changes of cage mates, and other similar individually innocuous manipulations) during at least 2 weeks. The model has been reported to result in long lasting changes of behavioral, neurochemical, neuroimmune, and neuroendocrinological variables. This resembles reward functions, that include decreased intracranial self-stimulation, and reflects anhedonia that is reversed by chronic, but not acute, antidepressant treatment. This CMS model can be used to screen and test potential antidepressant compounds and to develop new treatment strategies.The advantages of this model are its good predictive validity (behavioral changes are reversed by chronic treatment with a wide variety of antidepressants), face validity (almost all demonstrable symptoms of depression have been reproduced), and construct validity (CMS causes a generalized decrease in responsiveness to rewards). However, there is a common practical difficulty in carrying out CMS experiments, which are labor intensive, demanding of space, and of long duration. The procedure can be difficult to be established and data can be hardly replicated.
Social defeat stress: Social defeat stress (SDS) is a chronic and recurring factor in the lives of virtually all higher animal species. Humans experiencing social defeat show increased symptoms of depression, loneliness, anxiety, social withdrawal and a loss of self-esteem. Since the majority of stress stimuli in humans that lead to psychopathological changes are of social nature, SDS model have gained increasing attention since they might render useful to study certain endophenotypes of depression. During the stress period, the male rodent will be introduced into a different territory of other males for each day as an intruder. This causes it to be investigated, attacked and defeated by the residents. The consequent behavior changes in the subject caused by SDS, like decreased social interaction or lack of interest, are similar to some parts of human depression. Behavioral treatment and antidepressants can reverse these changes in an SDS model.Like CMS, SDS has good predictive validity (behavioral changes are reversed by chronic treatment with a wide variety of antidepressants), face validity (many symptoms of depression have been reproduced), and construct validity (causing a generalized decrease in responsiveness to rewards). SDS gives another validity that only chronic, but not acute, antidepressant administration can reverse the social aversion. One disadvantage of SDS model is the long duration. To apply an SDS model for studying human depression, the period of it should last at least 20 days or only anxiety symptoms could be induced. Only male rodents can be used for this model, since female rodents do not fight each other in a resident–intruder confrontation.
Early life stress models
Early adverse experiences such as traumatic life events in childhood result in an increased sensitivity to the effects of stress later in life and influence the vulnerability to depression. Suitable animal models could provide a basis for understanding potential mechanisms of environmental and developmental factors of individual differences in stress reactivity and vulnerability to disorders. Models of early life stress involve prenatal stress, early postnatal handling and maternal separation. All these treatments have been demonstrated to produce significant effects that last until adulthood.
Maternal deprivation: The maternal deprivation model is the most widely used early life stress model. This model manipulates the maternal separation of early life deprivation, in which pups are separated from the dam for 1–24 h per day during the first two postnatal weeks. Maternal separation results in increased anxiety- and depression-like behaviors and increased HPA response in adulthood.
Other models
Olfactory bulbectomy: Removal of the olfactory bulb in rodents results in a disruption of the limbic-hypothalamic axis with the consequence of behavioral, neurochemical, neuroendocrine and neuroimmune changes. Many of these resemble changes seen in depressed patients. It is still not clear how bulbectomy in animals actually relates to depression in humans; it might simply result from a high intensity of chronic stressor caused by chronic sensory deprivation. This model shows high predictive validity as it mimics the slow onset of antidepressant action reported in clinical studies. It responds chronic, but not sub-chronic, antidepressant treatment and does not response to other drugs.
Psychostimulant withdrawal (amphetamine, cocaine): In humans, withdrawal from chronic psychostimulants generates symptoms that have strong behavioral and physiological parallels to depression. Therefore, the examination of the behavioral effects of drug withdrawal in rodents may provide insights into the underlying neurobiological mechanisms and aid in the development of animal models of depression that are sensitive to antidepressant agents. Following withdrawal from drugs such as amphetamine or cocaine, rodents display behavioral changes that are highly similar to some aspects of depression in humans, such as anhedonia, and behaviors opposite to those seen after treatment with antidepressant drugs.
Genetically engineered mice: Only few generated mutant lines can be regarded as depression models, for example, α2A adrenergic receptor knockout mice, glucocorticoid receptor heterozygous mice, and cAMP response element-binding protein overexpressing mice.
Forward genetics: Forward genetics allows identifying relevant genes without any prior knowledge of genetic to the phenotype. Large scale random mutagenesis screens, like ENU, have resulted in a great number of mutants displaying depression or antidepressant-like behavior.
Evaluating symptoms
The degree of depression-like symptoms in an animal is evaluated using a number of tests. Tests provide a measure of an animal's response to inescapable stress (lack of attempt to escape is seen as despair/hopelessness) and to reward (lack of response indicates anhedonia), or to measure its degree of anxiety.
Despair-based
Forced-swimming test: The forced-swimming test (FST) is based on the observation that animals develop an immobile posture in an inescapable cylinder filled with water. In this test, immobility is interpreted as a passive stress-coping strategy or depression-like behavior (behavioral despair). After antidepressant administration, the animals will actively perform escape-directed behaviors with longer duration than animals with control saline treatment. FST is the most widely used tool in depression research, more specifically as a screen for acute antidepressants.The advantages of FST are that it is low-cost and a fast, reliable tool. It is also easy to handle and has proven its reliability across laboratories for testing potential antidepressant activities with a strong predictive validity and it allows rapid screening of large numbers of drugs. The major disadvantages of FST are that it has poor face and construct validities. The test is sensitive to acute treatment only, and its validity for non-monoamine antidepressants is uncertain
Tail suspension test: The TST, also known as tail suspension test, shares a common theoretical basis and behavioral measure with the FST. In the TST, mice are suspended by their tails using adhesive tape to a horizontal bar for a certain couple of minutes, and the time of immobility is recorded. Typically, the suspended rodents perform immediately escape-like behaviors, followed by developing an immobile posture. If antidepressants are given prior to the test, the subjects will be engaged in escape-directed behaviors for longer periods of time than after saline treatment, exhibiting a decrease in duration of immobility.A major advantage of the TST is that it is simple and inexpensive. A major disadvantage of the TST is that it is restricted to mice. Like FST, TST is sensitive to acute treatment only, and its validity for non-monoamine antidepressants is uncertain.
Reward-based
Sucrose preference: Rodents are born with an interest in sweet foods or solutions. Reduced preference for sweet solution in sucrose preference test represents anhedonia. This reduction can be reversed by treatment with chronic antidepressants. This test may measure the affective state and motivation of subject rodents; however, the face and construct validity of the sucrose preference test to measure depression-related behavior appears low.
Intracranial self-stimulation: Intracranial self-stimulation (ICSS) can be utilized in rodents to understand how drugs affect the function of brain reward system. In this paradigm, the animal is trained to spin a wheel to receive a current through electrodes implanted in its own brain for rewarding the hypothalamic stimulation. ICSS shares a common theoretical basis with the sucrose preference. Reduced preference for self-stimulating reward cognition represents a loss of interest, fatigue and a loss of energy. This usually occurs during depressive episodes, but, this reduction can be reversed by treatment with antidepressants. Like sucrose preference test, ICSS can measure the affective state and motivation of subject rodents, and again, further validation is needed for working as a model of depression.
Anxiety-based
Novelty-induced hypophagia: Hypophagia, one of the anxiety symptoms in rodents, is defined as the reduction in feeding in response to novelty, and it can be evoked by various novel features of the environment, including novel food, novel testing environment and novel food containers. Novelty-induced hypophagia (NIH) is a recently developed test which measures the latency and consumption of food in a novel unfamiliar environment. The test rather reflects the anxiolytic effects of antidepressants and the response is seen only after chronic treatment with antidepressants.
Open field: Rodents tend to avoid brightly illuminated areas, and this avoidance is interpreted as a symptom of anxiety. Open field is a bright enclosure and during the test rodents are placed in this arena thus forcing them to interact with a bright environment. The movement of the experimental subject will be recorded in distance and pathway.
Elevated plus maze: For the elevated plus maze test, the rodents are placed at the intersection of the four arms of the maze (two open, two closed), facing an open arm. The number of entries and time spent in each arm is recorded and valid results are obtained in a single 5-minute testing session. An increase in the open-arm time is an index of anti-anxiety behavior of rodents.
Dark/light box: The dark/light box test is also based on the rodents' innate aversion to brightly illuminated areas and on the spontaneous exploratory behavior of the animals. A natural conflict situation occurs when an animal is exposed to an unfamiliar environment or novel objects. The conflict is between the tendency to explore and the initial tendency to avoid the unfamiliar. The exploratory activity reflects the combined result of these tendencies in novel situations. The test apparatus of dark/light box consists of a dark compartment and an illuminated compartment. Drug-induced increases in behaviors in the white part of a two-compartment box are suggested as an index of anxiolytic activity.
Open field test, elevated plus maze test, and dark/light box test can work as an antidepressant screen by measuring anxiety-related behavior as an accompanying endophenotype of depression. It is known that some antidepressants will cause a decrease in behavior in these tests just like anxiolytics. However, the response to some antidepressants couldn't be detected. These tests each have their own problems and it is difficult to discriminate decreased anxiety-related avoidance from increased novelty-seeking in these tests.
Benefits of animal models
A benefit to this model of research is the production of antidepressants. While antidepressants are helpful, the effects of current antidepressant drugs are often significantly delayed, with improvements beginning around 3–6 weeks after treatment is started. Antidepressant screening tests provide only an end-point behavioral or physiological measure designed to assess the effect of the genetic, pharmacological, or environmental manipulation. This is unlike models which can be defined as an organism or a particular state of an organism that reproduces aspects of human pathology. Despite the clinical success of many antidepressant drugs, such as tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs), and serotonin reuptake inhibitors (SRIs), many individuals' symptoms are not adequately alleviated by medication alone, and other methods of treatment may be recommended.
Antidepressant and depression research is ongoing. There is a lot more knowledge now and people struggling have access to the tools they need when seeking help. Animal research has been a successful way for experts to gain this knowledge and it continues to have positive impacts in the medical field and beyond.
See also
Animal testing
Institutional Animal Care and Use Committees
Pit of despair, an apparatus used for animal models of clinical depression
Conditioned avoidance response test § Test of other drug effects
References
Major depressive disorder
Depression | Animal models of depression | Biology | 4,275 |
58,526,399 | https://en.wikipedia.org/wiki/Arcopilus%20aureus | Arcopilus aureus is a plant and soil fungus in the genus Arcopilus. It was first identified by A. H. Chivers in 1912, who named it Chaetomium aureum. It was later transferred to the genus Arcopilus by Wang and colleagues. The fungus has recently been recognized to have industrial use for the production of the metabolites resveratrol. and sclerotiorin Additionally, A. aureus has high lead tolerance and clearance, suggesting a potential role in environmental biotechnology.
History and taxonomy
The genus Chaetomium first characterized in 1817 by Gustav Kunze based on the globular morphology of the perithecia. However, no comprehensive monograph of the species within Chaetomium was written following Kunze's initial publication. In 1912, A. H. Chivers identified Chaetomium aureum while attempting to classify Chaetomium specimens in his herbarium. Ch. aureum was transferred to the genus Arcopilus in 2016 based on phylogenetic analysis of DNA-dependent RNA polymerase II large subunits by X.W. Wang and R. A. Samson.
Growth and morphology
Species within the genus Chaetomium are distinguished through morphological features. In general, the perithecium morphology of members of Chaetomium changes throughout maturation, changing from spherical and translucent, to globular or elongated and coloured when mature. Arcopilus aureus is morphologically similar to Chaetomium trilateral and Ch. fusiforme, leading to confusion in classification of species. However, the curvature of terminal hairs distinguish A. aureus from Ch. fusiforme, whereas spore discharge differentiates A. aureus from Ch. trilateral. Consistent with the perithecium morphology of the genus Chaetomium, the perithecia of A. aureus are flask-shaped, brown-black, and covered with long hairs. The terminal hairs (on the apex of the perithecium)' are olive-yellow, brown, or reddish-brown in colour, and curved at the tips. The lateral hairs (on the sides of the perithecium) are similarly olive-yellow in colour and uniform in diameter with less pronounced curvature at the tips. The growth rate of A. aureus is approximately 4-5mm per day. The mature ascomata are approximately 80-160μm in size, and maturation usually occurs within 10 days. Mature ascomata are olive-green and either spherical or oval-shaped. Ascomatal hairs are broad at the base, coiled at the tips, and can be either pale brown or yellow in colour. The asci are club-shaped with eight spores arranged either irregularly, or in two rows. Within the asci, young ascospores are translucent when young, but dark-green or brown when mature. Upon maturation, ascospores are boat, kidney, or lemon-shaped, with tapering and germ pores at both ends. A. aureus can be distinguished from similar species by its red, yellow and orange exudates producing colourful colonies in culture.
Ecology
Species in the genus Chaetomium are common saprophytic plant pathogens involved in the decomposition of plant matter in soil, and cellulose-based man-made materials. Chaetomium species have been specifically recognized in the decay of cotton, and as the agent of fruit and wood rot. Arcopilus aureus was first identified from isolates growing on plant species collected in New England. Since its initial discovery, A. aureus appears to have a large geographic range, having been identified in Morocco, Brazil, and India. A. aureus has been isolated from paper and dung, as well as pineapple field soil, and snap bean seeds. Additionally, A. aureus endophytic to plant species, notably Vitis vinifera, and Thymelaea lythroides, a medicinal plant used in Moroccan traditional medicine for cancer treatment.
Detection
Species within the genus Chaetomium are generally classified based on morphology of asci, ascospores, and terminal hairs. This however, leads to discrepancies in classification and determination of synonymous versus distinct species. For example, Dreyfuss (1976) considered Ch. aureum, Ch. trilaterale, Ch. fusiforme, Ch. cupreum, Ch. confusum, Ch. humicola, and Ch. rubrogenum to be a single species, whereas Ch. trilaterale was considered to be a distinct species by Millner et al. 1977. Molecular phylogenetic determination of fungi by means of protein electrophoresis has been reported, but with varying success. However, using isoelectric focusing in polyacrylamide gels to compare esterase enzymes in isolates of the Chaetomium species group, the number of esterase bands distinguishes Arcopilus aureus from its synonymous species. Although A. aureus is morphologically similar to Ch. trilaterale, protein electrophoresis shows the presence of two extra esterase bands in A. aureus. Additionally, protein electrophoresis shows that Ch. confusum, Ch. humicola, Ch. rubrogenum, and Ch. trilaterale are a synonymous species because of identical banding, supporting Dreyfuss's report in 1976.
Therapeutics
Species in the genus Chaetomium are sources of many secondary metabolites with anti-malarial, anti-bacterial, and anti-cancer properties. Notably, Arcopilus aureus has been found to produce resveratrol, and sclerotiorin.
Resveratrol has many benefits effects on human health; it has been found to reduce the progression of neurological diseases such as dementia, and is used to treat cardiovascular problems and ischemic conditions. Isolates from the genera Aspergillus, Botryosphaeria, Penicillium, Fusarium, Alternaria, Arcopilus, and Lasiodiplodia that are endophytic to Vinis vinifera were all found to produce varying levels of resveratrol. Of these isolates, A. aureus was found to produce the highest levels of resveratrol, based on the Liebermann test to detect a free para position in phenolic compounds, the acetic anhydride test to confirm presence a free -OH group, and quantification of resveratrol by HPLC.
A. aureus isolates endophytic to Thymelaea lythroides were shown to have anti-cancer properties. Hsp90 chaperone machinery maintains stability of activated protein kinase and transcription factors that contribute to tumorigenesis. Thus, inhibition of Hsp90 leads to cellular degradation of target oncoproteins. Accordingly, inhibition of the Hsp90 chaperone machinery is a potential therapeutic target for cancer. A. aureus isolates were found to produce sclerotiorin, which was tested for its ability to inhibit the Hsp90 machinery by examining Hsp90-mediated folding of the progesterone receptor. In vitro reconstitution of progesterone receptor re-folding following heat stress showed that sclerotiorin inhibited recovery of the progesterone receptor. Additionally, the inhibitory function of sclerotiorin is dependent on the oxygen atom in the heterocycle, as inhibitory function was abolished in compounds containing nitrogen instead of oxygen.
Environmental biotechnology
A potential usage of Arcopilus aureus in environmental biotechnology is bioremediation of soils contaminated with lead, organic matter, and abnormal pH levels. Previous studies have shown that species of the genus Chaetomium have been isolated from soils with high concentrations of metals, including lead. Additionally, growth of members of the genus Chaetomium are promoted by intermediate concentrations of lead. In agreement with early studies, A. aureus was isolated from soils with high lead concentration near a metallurgical plant in Brazil. Isolates of A. aureus shows high tolerance to lead nitrate and increased mycelial growth in the presence of metallic lead. Additionally, inoculation of the fungus in lead-contaminated soil showed a reduction in exchangeable lead concentration, in addition to maintenance of soil pH and establishment of organic matter in the presence of microbiota. The mechanism of lead reduction by A. aureus is unknown, but the two major hypotheses are: A. aureus produces oosporein, which creates a complex with lead, transforming it into insoluble pyromorphite.
References
Sordariales
Fungus species | Arcopilus aureus | Biology | 1,796 |
1,566,127 | https://en.wikipedia.org/wiki/BD%E2%88%9210%C2%B03166 | BD−10°3166 is a K-type main sequence star approximately 268 light-years away in the constellation of Crater. It was inconspicuous enough not be included in the Draper catalog (HD). The Hipparcos satellite also did not study it, so its true distance is poorly known. The distance measured by the Gaia spacecraft of 268 light years rules out a suggested companion star, LP 731-076, being its true binary star companion.
Stellar characteristics
The star is very enriched with metals, being two to three times as metal-rich as the Sun. Planets are common around such stars, and BD−10°3166 is not an exception. In 2000, the California and Carnegie Planet Search team discovered an extrasolar planet orbiting the star.
Planetary system
In 2000, the California and Carnegie Planet Search discovered a hot Jupiter-type extrasolar planet that has a minimum mass less than half that of Jupiter's, and which takes only 3.49 days to revolve around BD−10°3166.
See also
Lists of exoplanets
References
External links
Crater (constellation)
K-type main-sequence stars
Planetary systems with one confirmed planet
Durchmusterung objects | BD−10°3166 | Astronomy | 250 |
42,787,929 | https://en.wikipedia.org/wiki/2%2C3-Bis%28acetylmercaptomethyl%29quinoxaline | 2,3-Bis(acetylmercaptomethyl)quinoxaline (BAMMQ) is an antiviral agent which inhibits poliovirus RNA synthesis in vitro and in vivo and inhibits human herpesvirus 1 multiplication in vitro. It does not interfere with attachment, penetration or DNA synthesis, but interrupts a late stage in virus assembly and/or maturation.
BAMMQ was first identified as an antiviral agent in 1974, when it was shown to inhibit poliovirus growth by 99.8% or more at concentrations as low as 10−5 M. That same year, a patent was filed for BAMMQ and related quinoxaline compounds as antiviral agents, particularly noting their effectiveness against herpes simplex virus. The compound acts by specifically inhibiting viral RNA synthesis, with inhibition occurring within 30–60 minutes after addition of the drug. Studies demonstrated that while BAMMQ inhibited viral RNA replication, it did not directly affect viral protein synthesis. The compound's antiviral activity was found to be somewhat dependent on the culture medium composition and viral infection levels. This initial research also suggested that BAMMQ may act by preventing the reinitiation of viral RNA synthesis rather than blocking ongoing RNA synthesis.
BAMMQ has demonstrated broad-spectrum antiviral activity against multiple viruses. In addition to poliovirus, early studies showed it was effective against vesicular stomatitis virus, human parainfluenza virus type 3, Rous sarcoma virus, and herpes simplex virus. However, the compound's basic cytotoxicity and the fact that its antiviral efficiency could be partly reversed by increasing viral infection levels or using enriched medium limited its practical applications. The compound has also shown activity against plant viruses. It effectively inhibits both tobacco mosaic virus (TMV) and cowpea chlorotic mottle virus (CCMV) at relatively low concentrations, requiring only 0.015 millimolar (mM) for 90% inhibition of TMV and 0.03 mM for CCMV in leaf disk experiments. While the compound shows promise in leaf disk studies, research has shown that it does not reduce TMV accumulation in tobacco tissue cultures containing the compound.
BAMMQ has also been studied as an inhibitor of encephalomyocarditis (EMC) virus. While it allowed plating of high virus concentrations without causing extensive cell damage, no resistant viral mutants were observed in these studies.
References
Quinoxalines
Thioesters
Antiviral drugs
Acetyl compounds | 2,3-Bis(acetylmercaptomethyl)quinoxaline | Chemistry,Biology | 535 |
15,794,692 | https://en.wikipedia.org/wiki/Neurofilament%20light%20polypeptide | Neurofilament light polypeptide, also known as neurofilament light chain, abbreviated to NF-L or Nfl and with the HGNC name NEFL is a member of the intermediate filament protein family. This protein family consists of over 50 human proteins divided into 5 major classes, the Class I and II keratins, Class III vimentin, GFAP, desmin and the others, the Class IV neurofilaments and the Class V nuclear lamins. There are four major neurofilament subunits, NF-L, NF-M, NF-H and α-internexin. These form heteropolymers which assemble to produce 10 nm neurofilaments which are only expressed in neurons where they are major structural proteins, particularly concentrated in large projection axons. Axons are particularly sensitive to mechanical and metabolic compromise and as a result axonal degeneration is a significant problem in many neurological disorders. The detection of neurofilament subunits in CSF and blood has therefore become widely used as a biomarker of ongoing axonal compromise. The NF-L protein is encoded by the NEFL gene. Neurofilament light chain is a biomarker that can be measured with immunoassays in cerebrospinal fluid and plasma and reflects axonal damage in a wide variety of neurological disorders. It is a useful marker for disease monitoring in amyotrophic lateral sclerosis, multiple sclerosis, Alzheimer's disease, and more recently Huntington's disease. It is also promising marker for follow-up of patients with brain tumors. Higher levels of blood or CSF NF-L have been associated with increased mortality, as would be expected as release of this protein reflects ongoing axonal loss. Recent work performed as a collaboration between EnCor Biotechnology Inc. and the University of Florida showed that the NF-L antibodies employed in the most widely used NF-L assays are specific for cleaved forms of NF-L generated by proteolysis induced by cell death. Methods used in different studies for NfL measurement are sandwich enzyme-linked immunosorbent assay (ELISA), electrochemiluminescence, and high-sensitive single molecule array (SIMOA).
Neurofilament assembly and structure
It is associated with Charcot–Marie–Tooth disease 1F and 2E.
Interactions
Neurofilament light polypeptide has been shown to interact with:
MAP2,
Protein kinase N1, and
TSC1.
References
Further reading
External links
In
In
Human proteins
Biomarkers | Neurofilament light polypeptide | Biology | 553 |
38,145,479 | https://en.wikipedia.org/wiki/Jaynes%E2%80%93Cummings%E2%80%93Hubbard%20model | The Jaynes–Cummings–Hubbard (JCH) model is a many-body quantum system modeling the quantum phase transition of light. As the name suggests, the Jaynes–Cummings–Hubbard model is a variant on the Jaynes–Cummings model; a one-dimensional JCH model consists of a chain of N coupled single-mode cavities, each with a two-level atom. Unlike in the competing Bose–Hubbard model, Jaynes–Cummings–Hubbard dynamics depend on photonic and atomic degrees of freedom and hence require strong-coupling theory for treatment. One method for realizing an experimental model of the system uses circularly-linked superconducting qubits.
History
The combination of Hubbard-type models with Jaynes-Cummings (atom-photon) interactions near the photon blockade regime originally appeared in three, roughly simultaneous papers in 2006.
All three papers explored systems of interacting atom-cavity systems, and shared much of the essential underlying physics. Nevertheless, the term Jaynes–Cummings–Hubbard was not coined until 2008.
Properties
Using mean-field theory to predict the phase diagram of the JCH model, the JCH model should exhibit Mott insulator and superfluid phases.
Hamiltonian
The Hamiltonian of the JCH model is
():
where are Pauli operators for the two-level atom at the
n-th cavity. The is the tunneling rate between neighboring cavities, and is the vacuum Rabi frequency which characterizes to the photon-atom interaction strength. The cavity frequency is and atomic transition frequency is . The cavities are treated as periodic, so that the cavity labelled by n = N+1 corresponds to the cavity n = 1. Note that the model exhibits quantum tunneling; this process is similar to the Josephson effect.
Defining the photonic and atomic excitation number operators as and , the total number of excitations is a conserved quantity,
i.e., .
Two-polariton bound states
The JCH Hamiltonian supports two-polariton bound states when the photon-atom interaction is sufficiently strong. In particular, the two polaritons associated with the bound states exhibit a strong correlation such that they stay close to each other in position space. This process is similar to the formation of a bound pair of repulsive bosonic atoms in an optical lattice.
Further reading
D. F. Walls and G. J. Milburn (1995), Quantum Optics, Springer-Verlag.
References
Quantum optics | Jaynes–Cummings–Hubbard model | Physics | 505 |
7,696,546 | https://en.wikipedia.org/wiki/Structured%20analysis | In software engineering, structured analysis (SA) and structured design (SD) are methods for analyzing business requirements and developing specifications for converting practices into computer programs, hardware configurations, and related manual procedures.
Structured analysis and design techniques are fundamental tools of systems analysis. They developed from classical systems analysis of the 1960s and 1970s.
Objectives of structured analysis
Structured analysis became popular in the 1980s and is still in use today. Structured analysis consists of interpreting the system concept (or real world situations) into data and control terminology represented by data flow diagrams. The flow of data and control from bubble to the data store to bubble can be difficult to track and the number of bubbles can increase.
One approach is to first define events from the outside world that require the system to react, then assign a bubble to that event. Bubbles that need to interact are then connected until the system is defined. Bubbles are usually grouped into higher level bubbles to decrease complexity. Data dictionaries are needed to describe the data and command flows, and a process specification is needed to capture the transaction/transformation information.
SA and SD are displayed with structure charts, data flow diagrams and data model diagrams, of which there were many variations, including those developed by Tom DeMarco, Ken Orr, Larry Constantine, Vaughn Frick, Ed Yourdon, Steven Ward, Peter Chen, and others.
These techniques were combined in various published system development methodologies, including structured systems analysis and design method, profitable information by design (PRIDE), Nastec structured analysis & design, SDM/70 and the Spectrum structured system development methodology.
History
Structured analysis is part of a series of structured methods that represent a collection of analysis, design, and programming techniques that were developed in response to the problems facing the software world from the 1960s to the 1980s. In this timeframe most commercial programming was done in Cobol and Fortran, then C and BASIC. There was little guidance on "good" design and programming techniques, and there were no standard techniques for documenting requirements and designs. Systems were getting larger and more complex, and the information system development became harder and harder to do so."
As a way to help manage large and complex software, the following structured methods emerged since the end of the 1960s:
Structured programming in circa 1967 with Edsger Dijkstra - "Go To Statement Considered Harmful"
Niklaus Wirth Stepwise design in 1971
Nassi–Shneiderman diagram in 1972
Warnier/Orr diagram in 1974 - "Logical Construction of Programs"
HIPO in 1974 - IBM Hierarchy input-process-output (though this should really be output-input-process)
Structured design around 1975 with Larry Constantine, Ed Yourdon and Wayne Stevens.
Jackson structured programming in circa 1975 developed by Michael A. Jackson
Structured analysis in circa 1978 with Tom DeMarco, Edward Yourdon, Gane & Sarson, McMenamin & Palmer.
Structured analysis and design technique (SADT) developed by Douglas T. Ross
Yourdon structured method developed by Edward Yourdon.
Structured analysis and system specification published in 1978 by Tom DeMarco.
Structured systems analysis and design method (SSADM) first presented in 1983 developed by the UK Office of Government Commerce.
Essential Systems Analysis, proposed by Stephen M. McMenamin and John F. Palmer
IDEF0 based on SADT, developed by Douglas T. Ross in 1985.
Hatley-Pirbhai modeling, defined in "Strategies for Real-Time System Specification" by Derek J. Hatley and Imtiaz A. Pirbhai in 1988.
Modern Structured Analysis, developed by Edward Yourdon, after Essential System Analysis was published, and published in 1989.
Information technology engineering in circa 1990 with Finkelstein and popularised by James Martin.
According to Hay (1999) "information engineering was a logical extension of the structured techniques that were developed during the 1970s. Structured programming led to structured design, which in turn led to structured systems analysis. These techniques were characterized by their use of diagrams: structure charts for structured design, and data flow diagrams for structured analysis, both to aid in communication between users and developers, and to improve the analyst's and the designer's discipline. During the 1980s, tools began to appear which both automated the drawing of the diagrams, and kept track of the things drawn in a data dictionary". After the example of computer-aided design and computer-aided manufacturing (CAD/CAM), the use of these tools was named computer-aided software engineering (CASE).
Structured analysis topics
Single abstraction mechanism
Structured analysis typically creates a hierarchy employing a single abstraction mechanism. The structured analysis method can employ IDEF (see figure), is process driven, and starts with a purpose and a viewpoint. This method identifies the overall function and iteratively divides functions into smaller functions, preserving inputs, outputs, controls, and mechanisms necessary to optimize processes. Also known as a functional decomposition approach, it focuses on cohesion within functions and coupling between functions leading to structured data.
The functional decomposition of the structured method describes the process without delineating system behavior and dictates system structure in the form of required functions. The method identifies inputs and outputs as related to the activities. One reason for the popularity of structured analysis is its intuitive ability to communicate high-level processes and concepts, whether in single system or enterprise levels. Discovering how objects might support functions for commercially prevalent object-oriented development is unclear. In contrast to IDEF, the UML is interface driven with multiple abstraction mechanisms useful in describing service-oriented architectures (SOAs).
Approach
Structured analysis views a system from the perspective of the data flowing through it. The function of the system is described by processes that transform the data flows. Structured analysis takes advantage of information hiding through successive decomposition (or top down) analysis. This allows attention to be focused on pertinent details and avoids confusion from looking at irrelevant details. As the level of detail increases, the breadth of information is reduced. The result of structured analysis is a set of related graphical diagrams, process descriptions, and data definitions. They describe the transformations that need to take place and the data required to meet a system's functional requirements.
De Marco's approach consists of the following objects (see figure):
Context diagram
Data flow diagram
Process specifications
Data dictionary
Hereby the data flow diagrams (DFDs) are directed graphs. The arcs represent data, and the nodes (circles or bubbles) represent processes that transform the data. A process can be further decomposed to a more detailed DFD which shows the subprocesses and data flows within it. The subprocesses can in turn be decomposed further with another set of DFDs until their functions can be easily understood. Functional primitives are processes which do not need to be decomposed further. Functional primitives are described by a process specification (or mini-spec). The process specification can consist of pseudo-code, flowcharts, or structured English. The DFDs model the structure of the system as a network of interconnected processes composed of functional primitives. The data dictionary is a set of entries (definitions) of data flows, data elements, files, and databases. The data dictionary entries are partitioned in a top-down manner. They can be referenced in other data dictionary entries and in data flow diagrams.
Context diagram
Context diagrams are diagrams that represent the actors outside a system that could interact with that system. This diagram is the highest level view of a system, similar to block diagram, showing a, possibly software-based, system as a whole and its inputs and outputs from/to external factors.
This type of diagram according to Kossiakoff (2003) usually "pictures the system at the center, with no details of its interior structure, surrounded by all its interacting systems, environment and activities. The objective of a system context diagram is to focus attention on external factors and events that should be considered in developing a complete set of system requirements and constraints". System context diagrams are related to data flow diagram, and show the interactions between a system and other actors which the system is designed to face. System context diagrams can be helpful in understanding the context in which the system will be part of software engineering.
Data dictionary
A data dictionary or database dictionary is a file that defines the basic organization of a database. A database dictionary contains a list of all files in the database, the number of records in each file, and the names and types of each data field. Most database management systems keep the data dictionary hidden from users to prevent them from accidentally destroying its contents. Data dictionaries do not contain any actual data from the database, only bookkeeping information for managing it. Without a data dictionary, however, a database management system cannot access data from the database.
Database users and application developers can benefit from an authoritative data dictionary document that catalogs the organization, contents, and conventions of one or more databases. This typically includes the names and descriptions of various tables and fields in each database, plus additional details, like the type and length of each data element. There is no universal standard as to the level of detail in such a document, but it is primarily a distillation of metadata about database structure, not the data itself. A data dictionary document also may include further information describing how data elements are encoded. One of the advantages of well-designed data dictionary documentation is that it helps to establish consistency throughout a complex database, or across a large collection of federated databases.
Data flow diagrams
A data flow diagram (DFD) is a graphical representation of the "flow" of data through an information system. It differs from the system flowchart as it shows the flow of data through processes instead of computer hardware. Data flow diagrams were invented by Larry Constantine, developer of structured design, based on Martin and Estrin's "data flow graph" model of computation.
It is common practice to draw a system context diagram first which shows the interaction between the system and outside entities. The DFD is designed to show how a system is divided into smaller portions and to highlight the flow of data between those parts. This context-level data flow diagram is then "exploded" to show more detail of the system being modeled.
Data flow diagrams (DFDs) are one of the three essential perspectives of structured systems analysis and design method (SSADM). The sponsor of a project and the end users will need to be briefed and consulted throughout all stages of a system's evolution. With a data flow diagram, users are able to visualize how the system will operate, what the system will accomplish, and how the system will be implemented. The old system's data flow diagrams can be drawn up and compared with the new system's data flow diagrams to draw comparisons to implement a more efficient system. Data flow diagrams can be used to provide the end user with a physical idea of where the data they input ultimately has an effect upon the structure of the whole system from order to dispatch to recook. How any system is developed can be determined through a data flow diagram.
Structure chart
A structure chart (SC) is a chart that shows the breakdown of the configuration system to the lowest manageable levels. This chart is used in structured programming to arrange the program modules in a tree structure. Each module is represented by a box which contains the name of the modules. The tree structure visualizes the relationships between the modules.
Structure charts are used in structured analysis to specify the high-level design, or architecture, of a computer program. As a design tool, they aid the programmer in dividing and conquering a large software problem, that is, recursively breaking a problem down into parts that are small enough to be understood by a human brain. The process is called top-down design, or functional decomposition. Programmers use a structure chart to build a program in a manner similar to how an architect uses a blueprint to build a house. In the design stage, the chart is drawn and used as a way for the client and the various software designers to communicate. During the actual building of the program (implementation), the chart is continually referred to as the master-plan.
Structured design
Structured design (SD) is concerned with the development of modules and the synthesis of these modules in a so-called "module hierarchy". In order to design optimal module structure and interfaces two principles are crucial:
Cohesion which is "concerned with the grouping of functionally related processes into a particular module", and
Coupling relates to "the flow of information or parameters passed between modules. Optimal coupling reduces the interfaces of modules and the resulting complexity of the software".
Structured design was developed by Larry Constantine in the late 1960s, then refined and published with collaborators in the 1970s; see Larry Constantine: structured design for details. has proposed his own approach which consists of three main objects :
structure charts
module specifications
data dictionary.
The structure chart aims to show "the module hierarchy or calling sequence relationship of modules. There is a module specification for each module shown on the structure chart. The module specifications can be composed of pseudo-code or a program design language. The data dictionary is like that of structured analysis. At this stage in the software development lifecycle, after analysis and design have been performed, it is possible to automatically generate data type declarations", and procedure or subroutine templates.
Criticisms
Problems with data flow diagrams have included the following:
Choosing bubbles appropriately
Partitioning bubbles in a meaningful and mutually agreed upon manner,
Documentation size needed to understand the Data Flows,
Data flow diagrams are strongly functional in nature and thus subject to frequent change
Though "data" flow is emphasized, "data" modeling is not, so there is little understanding the subject matter of the system
Customers have difficulty following how the concept is mapped into data flows and bubbles
Designers must shift the DFD organization into an implementable format
See also
Event partitioning
Flow-based programming
HIPO
Jackson structured programming
Prosa Structured Analysis Tool
Soft systems methodology
References
Further reading
Tom DeMarco (1978). Structured Analysis and System Specification. Yourdon.
Derek J. Hatley, Imtiaz A. Pirbhai (1988). Strategies for Real Time System Specification. John Wiley and Sons Ltd.
Stephen J. Mellor und Paul T. Ward (1986). Structured Development for Real-Time Systems: Implementation Modeling Techniques: 003. Prentice Hall.
Edward Yourdon (1989). Modern Structured Analysis, Yourdon Press Computing Series, 1989,
Keith Edwards (1993). Real-Time Structured Methods, System Analysis. Wiley.
External links
Structured Analysis Wiki
Three views of structured analysis CRaG Systems, 2004.
Software design | Structured analysis | Engineering | 2,974 |
49,131,748 | https://en.wikipedia.org/wiki/ADAM20 | Disintegrin and metalloproteinase domain-containing protein 20 is an enzyme that in humans is encoded by the ADAM20 gene. It is a membrane disintegrin-metalloprotease that belongs to the ADAM family. It is exclusively expressed in Testes and is similar to sperm cell-specific fertilins -alpha and -beta.
Its cDNA is tightly linked to marker SHGC-36001 on chromosome 14q24.1. ADAM20 is related to fertilin α (ADAM1A/B pseudogene), fertilin β (ADAM2), and fertilin γ (ADAM9). In humans, fertilin α has recently been deactivated so ADAM20 may be the functional equivalent fertilin α in humans.
Structure
In common with other ADAM family members, ADAM20 contains a N-terminal reprolysin family propeptide (residues 57–159), reprolysin (M12B) family zinc metalloprotease domain (207–395), disintegrin domain (416–488), and a C-terminal ADAM cysteine-rich domain (493–605).
The propeptide acts both a signal peptide and an activator domain. This prodomain has a cysteine that interacts with a zinc in the catalytic domain, thereby preventing the catalytic activity of the protein.When the pro-protein domain is cleaved, this cysteine zinc bond is broken and the protein is activated. A notable variant showed an amino acid difference in the pro protein domain that prevented the cleavage of this domain which prevented the fusion of the sperm cell to an egg.
References
Proteases
Protein families | ADAM20 | Chemistry,Biology | 359 |
56,853,695 | https://en.wikipedia.org/wiki/Hickson%2044 | Hickson 44 (HCG 44) is a group of galaxies in the constellation Leo. As Arp 316, a part of this group is also designated as group of galaxies in the Atlas of Peculiar Galaxies.
Members
References
44
Leo (constellation) | Hickson 44 | Astronomy | 51 |
612,874 | https://en.wikipedia.org/wiki/Acylation | In chemistry, acylation is a broad class of chemical reactions in which an acyl group () is added to a substrate. The compound providing the acyl group is called the acylating agent. The substrate to be acylated and the product include the following:
alcohols, esters
amines, amides
arenes or alkenes, ketones
A particularly common type of acylation is acetylation, the addition of the acetyl group. Closely related to acylation is formylation, which employ sources of "HCO+ in place of "RCO+".
Examples
Because they form a strong electrophile when treated with Lewis acids, acyl halides are commonly used as acylating agents. For example, Friedel–Crafts acylation uses acetyl chloride () as the agent and aluminum chloride () as a catalyst to add an acetyl group to benzene:
This reaction is an example of electrophilic aromatic substitution.
Acyl halides and acid anhydrides of carboxylic acids are also common acylating agents. In some cases, active esters exhibit comparable reactivity. All react with amines to form amides and with alcohols to form esters by nucleophilic acyl substitution.
Acylation can be used to prevent rearrangement reactions that would normally occur in alkylation. To do this an acylation reaction is performed, then the carbonyl is removed by Clemmensen reduction or a similar process.
Acylation in biology
Protein acylation is the post-translational modification of proteins via the attachment of functional groups through acyl linkages. Protein acylation has been observed as a mechanism controlling biological signaling. One prominent type is fatty acylation, the addition of fatty acids to particular amino acids (e.g. myristoylation, palmitoylation or palmitoleoylation). Different types of fatty acids engage in global protein acylation. Palmitoleoylation is an acylation type where the monounsaturated fatty acid palmitoleic acid is covalently attached to serine or threonine residues of proteins. Palmitoleoylation appears to play a significant role in the trafficking, targeting, and function of Wnt proteins.
See also
Hydroacylation
Acetyl
Ketene
References
Organic reactions | Acylation | Chemistry | 494 |
31,837,733 | https://en.wikipedia.org/wiki/Socio-ecological%20system | A social-ecological system consists of 'a bio-geo-physical' unit and its associated social actors and institutions. Social-ecological systems are complex and adaptive and delimited by spatial or functional boundaries surrounding particular ecosystems and their context problems.
Definitions
A social-ecological system (SES) can be defined as: (p. 163)
A coherent system of biophysical and social factors that regularly interact in a resilient, sustained manner;
A system that is defined at several spatial, temporal, and organisational scales, which may be hierarchically linked;
A set of critical resources (natural, socio-economic, and cultural) whose flow and use is regulated by a combination of ecological and social systems; and
A perpetually dynamic, complex system with continuous adaptation.
Scholars have used the concept of social-ecological systems to emphasise humans as part of nature and to stress that the delineation between social systems and ecological systems is artificial and arbitrary. While resilience has somewhat different meaning in social and ecological context, the SES approach holds that social and ecological systems are linked through feedback mechanisms, and that both display resilience and complexity.
Theoretical foundations
Social-ecological systems are based on the concept that humans are a part of—not separate from—nature. This concept, which holds that the delineation between social systems and natural systems is arbitrary and artificial, was first put forth by Berkes and Folke, and its theory was further developed by Berkes et al. More recent research into social-ecological system theory has pointed to social-ecological keystones as critical to the structure and function of these systems, and to biocultural diversity as essential to the resilience of these systems.
Integrative approaches
Through to the final decades of the twentieth century, the point of contact between social sciences and natural sciences was very limited in dealing with social-ecological systems. Just as mainstream ecology had tried to exclude humans from the study of ecology, many social science disciplines had ignored the environment altogether and limited their scope to humans. Although some scholars (e.g. Bateson 1979) had tried to bridge the nature-culture divide, the majority of studies focused on investigating processes within the social domain only, treating the ecosystem largely as a "black box" and assuming that if the social system performs adaptively or is well organised institutionally it will also manage the environmental resource base in a sustainable fashion.
This changed through the 1970s and 1980s with the rise of several subfields associated with the social sciences but explicitly including the environment in the framing of the issues. These subfields are:
Environmental ethics, which arose from the need to develop a philosophy of relations between humans and their environment, because conventional ethics only applied to relations among people.
Political ecology, which expands ecological concerns to respond to the inclusion of cultural and political activity within an analysis of ecosystems that are significantly but not always entirely socially constructed.
Environmental history which arose from the rich accumulation of material documenting relationships between societies and their environment.
Ecological economics which examines the link between ecology and economics by bridging the two disciplines to promote an integrated view of economics within the ecosystem.
Common property which examines the linkages between resource management and social organisation, analysing how institutions and property rights systems deal with the dilemma of the "tragedy of the commons".
Traditional ecological knowledge, which refers to ecological understanding built, not by experts, but by people who live and use the resources of a place.
Each of the six areas summarised is a bridge spanning different combinations of natural science and social science thinking.
Conceptual foundations and origins
Elinor Ostrom and her many co-researchers developed a comprehensive "Social-Ecological Systems (SES) framework", which includes much of the theory of common-pool resources and collective self-governance. It draws heavily on systems ecology and complexity theory. The studies of SES include some central societal concerns (e.g. equity and human wellbeing) that have traditionally received little attention in complex adaptive systems theory, and there are areas of complexity theory (e.g. quantum physics) that have little direct relevance for understanding SES.
SES theory incorporates ideas from theories relating to the study of resilience, robustness, sustainability, and vulnerability (e.g. Levin 1999, Berkes et al. 2003, Gunderson and Holling 2002, Norberg and Cumming 2008), but it is also concerned with a wider range of SES dynamics and attributes than any one of these terms implies. While SES theory draws on a range of discipline-specific theories, such as island biogeography, optimal foraging theory, and microeconomic theory, it is much broader than any of these individual theories alone.
SES theory emerged from a combination of disciplines and the notion of complexity developed through the work of many scholars, including the Santa Fe Institute (2002). Due to the social context in which SES research was placed, and the possibility of SES research translating into recommendations that may affect real people, SES research was seen as more "self-conscious" and "pluralistic" in its perspectives than complexity theory.
Studying SESs from a complex system perspective attempts to link different disciplines into a body of knowledge that is applicable to serious environmental problems. Management processes in the complex systems can be improved by making them adaptive and flexible, able to deal with uncertainty and surprise, and by building capacity to adapt to change. SESs are both complex and adaptive, meaning that they require continuous testing, learning about, and developing knowledge and understanding in order to cope with change and uncertainty.
A complex system differs from a simple system in that it has a number of attributes that cannot be observed in simple systems, such as nonlinearity, uncertainty, emergence, scale, and self-organisation.
Nonlinearity
Nonlinearity is related to fundamental uncertainty. It generates path dependency, which refers to local rules of interaction that change as the system evolves and develops. A consequence of path dependency is the existence of multiple basins of attraction in ecosystem development and the potential for threshold behaviour and qualitative shifts in system dynamics under changing environmental influences. An example for non-linearity in socio-ecological systems is illustrated by the figure on "Conceptual Model of Socioecological Drivers of Change".
Emergence
Emergence is the appearance of behaviour that could not be anticipated from knowledge of the parts of the system alone.
Scale
Scale is important when dealing with complex systems. In a complex system many subsystems can be distinguished; and since many complex systems are hierarchic, each subsystem is nested in a larger subsystem etc. For example, a small watershed may be considered an ecosystem, but it is a part of a larger watershed that can also be considered an ecosystem and a larger one that encompasses all the smaller watersheds. Phenomena at each level of the scale tend to have their own emergent properties, and different levels may be coupled through feedback relationships. Therefore, complex systems should always be analysed or managed simultaneously at different scales.
Self organisation
Self organisation is one of the defining properties of complex systems. The basic idea is that open systems will reorganise at critical points of instability. Holling's adaptive renewal cycle is an illustration of reorganisation that takes place within the cycles of growth and renewal. The self-organisation principle, operationalised through feedback mechanisms, applies to many biological systems, social systems and even to mixture of simple chemicals. High speed computers and nonlinear mathematical techniques help simulate self-organisation by yielding complex results and yet strangely ordered effects. The direction of self-organisation will depend on such things as the system's history; it is path dependent and difficult to predict.
Examples of conceptual framework for analysis
There are several conceptual frameworks developed in relation to the resilience approach.
A framework that focuses on knowledge and understanding of ecosystem dynamics, how to navigate it through management practices, institutions, organisations and social networks and how they relate to drivers of change (Picture A).
Alternative conceptual model illustrates how it is meaningful to consider a wide range of socio-ecological system properties potentially influencing agricultural intensification, rather than singling out macro-drivers such as population pressure as the primary metric of agrarian change and intensification (Picture B).
A conceptual model in relation to the robustness of social-ecological systems. There resource could be water or a fishery and the resource users could be farmers irrigating or inshore fishermen. Public infrastructure providers involve, for example, local users associations and government bureaus and public infrastructure include institutional rules and engineering works. The number refer to links between the entities and are exemplified in the source of the figure (Picture C).
MuSIASEM or Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism. This is a method of accounting used to analyse social-ecosystems and to simulate possible patterns of development.
Role of traditional knowledge
Berkes and colleagues distinguish four sets of elements which can be used to describe social-ecological system characteristics and linkages:
Ecosystems
Local knowledge
People and technology
Property rights institutions
Knowledge acquisition of SESs is an ongoing, dynamic learning process, and such knowledge often emerges with people's institutions and organisations. To remain effective it requires institutional framework and social networks to be nested across scales. It is thus the communities which interact with ecosystems on the daily basis and over long periods of time that possess the most relevant knowledge of resource and ecosystem dynamics, together with associated management practices. Some scholars have suggested that management and governance of SESs may benefit from combination of different knowledge systems; others have attempted to import such knowledge into the scientific knowledge field There also those who have argued that it would be difficult to separate these knowledge systems from their institutional and cultural contexts, and those who have questioned the role of traditional and local knowledge systems in the current situation of pervasive environmental change and globalised societies. Other scholars have claimed that valuable lessons can be extracted from such systems for complex system management; lessons that also need to account for interactions across temporal and spatial scales and organisational and institutional levels, and in particular during periods of rapid change, uncertainty and system reorganisation.
Adaptive cycle
The adaptive cycle, originally conceptualised by Holling (1986) interprets the dynamics of complex ecosystems in response to disturbance and change. In terms of its dynamics, the adaptive cycle has been described as moving slowly from exploitation (r) to conservation (K), maintaining and developing very rapidly from K to release (Omega), continuing rapidly to reorganisation (alpha) and back to exploitation (r). Depending on the particular configuration of the system, it can then begin a new adaptive cycle or alternatively it may transform into a new configuration, shown as an exit arrow. The adaptive cycle is one of the five heuristics used to understand social-ecological system behaviour. The other four heuristics—resilience, panarchy, transformability, and adaptability—are of considerable conceptual appeal, and it is claimed to be generally applicable to ecological and social systems as well as to coupled social-ecological systems. Adaptability is the capacity of a social-ecological system to learn and adjust to both internal and external processes. Transformability is the capacity of a system to transform into a completely new system, when ecological, economic, or social structures make the current system unsustainable. Adaptability and transformability are prerequisites for resilience.
The two main dimensions that determine changes in an adaptive cycle are connectedness and potential. The connectedness dimension is the visual depiction of a cycle and stands for the ability to internally control its own destiny. It "reflects the strength of internal connections that mediate and regulate the influences between inside processes and the outside world" (p. 50). The potential dimension is represented by the vertical axis, and stands for the "inherent potential of a system that is available for change" (p. 393). Social or cultural potential can be characterised by the "accumulated networks of relationships-friendship, mutual respect, and trust among people and between people and institutions of governance" (p. 49). According to the adaptive cycle heuristic, the levels of both dimensions differ during the course of the cycle along the four phases. The adaptive cycle thus predicts that the four phases of the cycle can be distinguished based on distinct combinations of high or low potential and connectedness.
The notion of panarchy and adaptive cycles has become an important theoretical lens to describe the resilience of ecological systems and, more recently, social-ecological systems. Although panarchy theory originates in ecology, it has found widespread applications in other disciplines. For example, in management, Wieland (2021) describes a panarchy that represents the planetary, political-economic, and supply chain levels. Hereby, the panarchical understanding of the supply chain leads to a social-ecological interpretation of supply chain resilience.
Adaptive governance
The resilience of social-ecological systems is related to the degree of the shock that the system can absorb and remain within a given state. The concept of resilience is a promising tool for analysing adaptive change towards sustainability because it provides a way for analysing how to manipulate stability in the face of change.
In order to emphasise the key requirements of a social-ecological system for successful adaptive governance, Folke and colleagues contrasted case studies from the Florida Everglades and the Grand Canyon. Both are complex social-ecological systems that have experiences unwanted degradation of their ecosystem services, but differ substantially in terms of their institutional make-up.
The governance structure in the Everglades is dominated by the interests of agriculture and environmentalists who have been in conflict over the need to conserve the habitat at the expense of agricultural productivity throughout history. Here, a few feedbacks between the ecological system and the social system exist, and the SES is unable to innovate and adapt (the α-phase of reorganisation and growth).
In contrast, different stakeholders have formed an adaptive management workgroup in the case of Grand Canyon, using planned management interventions and monitoring to learn about changes occurring in the ecosystem including the best ways to subsequently manage them. Such an arrangement in governance creates the opportunity for institutional learning to take place, allowing for a successful period of reorganisation and growth. Such an approach to institutional learning is becoming more common as NGOs, scientist and communities collaborate to manage ecosystems.
Links to sustainable development
The concept of social-ecological systems has been developed in order to provide both a promising scientific gain as well as impact on problems of sustainable development. A close conceptual and methodological relation exists between the analysis of social-ecological systems, complexity research, and transdisciplinarity. These three research concepts are based on similar ideas and models of reasoning. Moreover, the research on social-ecological systems almost always uses transdisciplinary mode of operation in order to achieve an adequate problem orientation and to ensure integrative results. Problems of sustainable development are intrinsically tied to the social-ecological system defined to tackle them. This means that scientists from the relevant scientific disciplines or field of research as well as the involved societal stakeholders have to be regarded as elements of the social-ecological system in question.
See also
Relational mobility
References
Further reading
Aravindakshan, S., Krupnik, T.J., Groot, J.C., Speelman, E.N., Amjath-Babu, T.S. and Tittonell, P., 2020. Multi-level socioecological drivers of agrarian change: Longitudinal evidence from mixed rice-livestock-aquaculture farming systems of Bangladesh. Agricultural Systems, 177, p. 102695.(Aravindakshan et al. 2020)
Ecology Info Center, 2022. What is Panarchy? http://environment-ecology.com/general-systems-theory/535-panarchy.html.
Gunderson, L. and Holling, C.S. (2002). Panarchy: understanding transformations in human and natural systems. Island Press, Washington, D.C., USA.
Maclean K, Ross H, Cuthill M, Rist P. 2013. Healthy country, healthy people: An Australian Aboriginal organisation's adaptive governance to enhance its social-ecological system. Geoforum. 45:94–105.
Ecosystems | Socio-ecological system | Biology | 3,308 |
58,671 | https://en.wikipedia.org/wiki/Tripropellant%20rocket | A tripropellant rocket is a rocket that uses three propellants, as opposed to the more common bipropellant rocket or monopropellant rocket designs, which use two or one propellants, respectively. Tripropellant systems can be designed to have high specific impulse and have been investigated for single-stage-to-orbit designs. While tripropellant engines have been tested by Rocketdyne and NPO Energomash, no tripropellant rocket has been flown.
There are two different kinds of tripropellant rockets. One is a rocket engine which mixes three separate streams of propellants, burning all three propellants simultaneously. The other kind of tripropellant rocket is one that uses one oxidizer but two fuels, burning the two fuels in sequence during the flight.
Simultaneous burn
Simultaneous tripropellant systems often involve the use of a high energy density metal additive, like beryllium or lithium, with existing bipropellant systems. In these motors, the burning of the fuel with the oxidizer provides activation energy needed for a more energetic reaction between the oxidizer and the metal. While theoretical modeling of these systems suggests an advantage over bipropellant motors, several factors limit their practical implementation, including the difficulty of injecting solid metal into the thrust chamber; heat, mass, and momentum transport limitations across phases; and the difficulty of achieving and sustaining combustion of the metal.
In the 1960s, Rocketdyne test-fired an engine using a mixture of liquid lithium, gaseous hydrogen, and liquid fluorine to produce a specific impulse of 542 seconds, likely the highest measured such value for a chemical rocket motor. Despite the high specific impulse, the technical difficulties of the combination and the hazardous nature of the propellants ensured the engine has not been developed further.
Sequential burn
In sequential tripropellant rockets, the fuel is changed during flight, so the motor can combine the high thrust of a dense fuel like kerosene early in flight with the high specific impulse of a lighter fuel like liquid hydrogen (LH2) later in flight. The result is a single engine providing some of the benefits of staging.
For example, injecting a small amount of liquid hydrogen into a kerosene-burning engine can yield significant specific impulse improvements without compromising propellant density. This was demonstrated by the RD-701 achieving a specific impulse of 415 seconds in vacuum (higher than the pure LH2/LOX RS-68), where a pure kerosene engine with a similar expansion ratio would achieve 330–340 seconds.
Although liquid hydrogen delivers the largest specific impulse of the plausible rocket fuels, it also requires huge structures to hold it due to its low density. These structures can weigh a lot, offsetting the light weight of the fuel itself to some degree, and also result in higher drag while in the atmosphere. While kerosene has lower specific impulse, its higher density results in smaller structures, which reduces stage mass, and furthermore reduces losses to atmospheric drag. In addition, kerosene-based engines generally provide higher thrust, which is important for takeoff, reducing gravity drag. So in general terms there is a "sweet spot" in altitude where one type of fuel becomes more practical than the other.
Traditional rocket designs use this sweet spot to their advantage via staging. For instance the Saturn Vs used a lower stage powered by RP-1 (kerosene) and upper stages powered by LH2. Some of the early Space Shuttle design efforts used similar designs, with one stage using kerosene into the upper atmosphere, where an LH2 powered upper stage would light and go on from there. The later Shuttle design is somewhat similar, although it used solid rockets for its lower stages.
SSTO rockets could simply carry two sets of engines, but this would mean the spacecraft would be carrying one or the other set "turned off" for most of the flight. With light enough engines this might be reasonable, but an SSTO design requires a very high mass fraction and so has razor-thin margins for extra weight.
At liftoff the engine typically burns both fuels, gradually changing the mixture over altitude in order to keep the exhaust plume "tuned" (a strategy similar in concept to the plug nozzle but using a normal bell), eventually switching entirely to LH2 once the kerosene is burned off. At that point the engine is largely a straight LH2/LOX engine, with an extra fuel pump hanging onto it.
The concept was first explored in the US by Robert Salkeld, who published the first study on the concept in Mixed-Mode Propulsion for the Space Shuttle, Astronautics & Aeronautics, which was published in August 1971. He studied a number of designs using such engines, both ground-based and a number that were air-launched from large jet aircraft. He concluded that tripropellant engines would produce gains of over 100% (essentially more than double) in payload fraction, reductions of over 65% in propellant volume and better than 20% in dry weight. A second design series studied the replacement of the Shuttle's SRBs with tripropellant based boosters, in which case the engine almost halved the overall weight of the designs. His last full study was on the Orbital Rocket Airplane which used both tripropellant and (in some versions) a plug nozzle, resulting in a spaceship only slightly larger than a Lockheed SR-71, able to operate from traditional runways.
Tripropellant engines were built in Russia. Kosberg and Glushko developed a number of experimental engines in 1988 for a SSTO spaceplane called MAKS, but both the engines and MAKS were cancelled in 1991 due to a lack of funding. Glushko's RD-701 was built and test fired, however, and although there were some problems, Energomash feels that the problems are entirely solvable and that the design does represent one way to reduce launch costs by about 10 times.
References
Rocket propulsion
Rocket engines
Rocket engines using hydrogen propellant
Rocket engines using kerosene propellant
Rocket engines by propellant | Tripropellant rocket | Technology | 1,252 |
31,397,428 | https://en.wikipedia.org/wiki/D-value%20%28microbiology%29 | In microbiology, in the context of a sterilization procedure, the D-value or decimal reduction time (or decimal reduction dose) is the time (or dose of an antimicrobial drug) required, at a given condition (e.g. temperature) or set of conditions, to achieve a one-log reduction, that is, to kill 90% of relevant microorganisms. A D-value is denoted with the capital letter "D". Thus, after an exposure time of 1 D, only 10% of the organisms originally present in a microbial colony would remain. The term originated in assessments of microbes' thermal resistance and in thermal death time analysis; however, it now has analogous uses in other microbial resistance and death rate applications, such as for ethylene oxide and radiation processing.
Details
Use of D-values is based on the assumption that the procedure in question causes the number of living microorganisms to decay exponentially. From this perspective, D-values can be understood as roughly analogous to half lives of radioactive substances, however a half life involves a reduction of 50% rather than 90%. The half life is actually roughly 30% () of the D-value, so if D = 10 minutes, the number of living microorganisms will be halved in about 3 minutes.
Generally, each lot of a sterilization-resistant organism will have its own specific D-value. Determining a D-value requires an experiment, but only gives the D-value under the specific conditions of that experiment. D-values are unique to the conditions of the environment that the bacteria currently exists in.
In the context of thermal analysis it is typical practice to subscript the "D" with an indication of temperature. For example, given a hypothetical organism which is reduced by 90% after exposure to temperatures of 150° C for 20 minutes, the D-value would be written as D150C = 20 minutes. In the US, the temperature is usually indicated in degrees Fahrenheit; a notation like D230 should be understood to mean D230F (D110C). When describing D-value generally for any temperature, like in the heading of a table, a common abbreviation is DT (where T stands for the temperature), where specific values for T may be given elsewhere. A numeric subscript may also be used to indicate some other level of reduction than 90%; for example, D10 denotes the time required for a 10% reduction.
D-values are sometimes used to express a disinfectant's efficiency in reducing the number of microbes present in a given environment.
See also
Food microbiology
Pasteurisation
Sterilisation
z-value
References
Microbiology | D-value (microbiology) | Chemistry,Biology | 563 |
50,506,112 | https://en.wikipedia.org/wiki/Homarine | Homarine (N-methyl picolinic acid betaine) is an organic compound with the chemical formula C7H7NO2. It is commonly found in aquatic organisms from phytoplankton to crustaceans, although it is not found in vertebrates.
Biological function
Homarine functions as an osmolyte by affecting the ionic strength of the cytosol and thereby maintaining osmotic pressure within the cell.
Homarine may also act as a methyl group donor in the biosynthesis of various other N-methylated chemicals, such as glycine betaine and choline. The process of methyl donation converts homarine into picolinic acid and is reversible.
Etymology
The name of this chemical comes from the initial discovery of the molecule in 1933 in lobster tissue: the word homarine as an adjective means "of, or relating to, lobsters" (i.e. genus Homarus).
References
Solutions
Biosynthesis
Physiology articles about cellular physiology
Diffusion
Methylation | Homarine | Physics,Chemistry | 209 |
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