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11,817,160 | https://en.wikipedia.org/wiki/Rigidoporus%20vinctus | Rigidoporus vinctus is a plant pathogen infecting bananas.
References
Fungi described in 1852
Fungal plant pathogens and diseases
Banana diseases
Meripilaceae
Taxa named by Miles Joseph Berkeley
Fungus species | Rigidoporus vinctus | [
"Biology"
] | 41 | [
"Fungi",
"Fungus species"
] |
11,817,197 | https://en.wikipedia.org/wiki/Cordana%20johnstonii | Cordana johnstonii is an ascomycete fungus that is a plant pathogen. It produces cordana leaf spot on bananas.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Enigmatic Ascomycota taxa
Banana diseases
Fungi described in 1971
Fungus species | Cordana johnstonii | [
"Biology"
] | 62 | [
"Fungi",
"Fungus species"
] |
11,817,228 | https://en.wikipedia.org/wiki/Neocordana%20musae | Neocordana musae (formerly Cordana musae) is an ascomycete fungus that is a plant pathogen. It produces cordana leaf spot on bananas.
External links
Index Fungorum
USDA ARS Fungal Database
Enigmatic Ascomycota taxa
Fungal plant pathogens and diseases
Banana diseases
Fungus species | Neocordana musae | [
"Biology"
] | 65 | [
"Fungi",
"Fungus species"
] |
11,817,280 | https://en.wikipedia.org/wiki/Fusarium%20pallidoroseum | Fusarium pallidoroseum is a fungal and plant pathogen infecting banana, maize and pigeonpea.
References
External links
USDA ARS Fungal Database
pallidoroseum
Fungal plant pathogens and diseases
Banana diseases
Maize diseases
Vegetable diseases
Fungi described in 1886
Fungus species | Fusarium pallidoroseum | [
"Biology"
] | 58 | [
"Fungi",
"Fungus species"
] |
11,817,317 | https://en.wikipedia.org/wiki/Mechanical%20explanations%20of%20gravitation | Mechanical explanations of gravitation (or kinetic theories of gravitation) are attempts to explain the action of gravity by aid of basic mechanical processes, such as pressure forces caused by pushes, without the use of any action at a distance. These theories were developed from the 16th until the 19th century in connection with the aether. However, such models are no longer regarded as viable theories within the mainstream scientific community because general relativity is now the standard model to describe gravitation without the use of actions at a distance. Modern "quantum gravity" hypotheses also attempt to describe gravity by more fundamental processes such as particle fields, but they are not based on classical mechanics.
Screening
This theory is probably the best-known mechanical explanation, and was developed for the first time by Nicolas Fatio de Duillier in 1690, and re-invented, among others, by Georges-Louis Le Sage (1748), Lord Kelvin (1872), and Hendrik Lorentz (1900), and criticized by James Clerk Maxwell (1875), and Henri Poincaré (1908).
The theory posits that the force of gravity is the result of tiny particles or waves moving at high speed in all directions, throughout the universe. The intensity of the flux of particles is assumed to be the same in all directions, so an isolated object A is struck equally from all sides, resulting in only an inward-directed pressure but no net directional force. With a second object B present, however, a fraction of the particles that would otherwise have struck A from the direction of B is intercepted, so B works as a shield, so-to-speak—that is, from the direction of B, A will be struck by fewer particles than from the opposite direction. Likewise, B will be struck by fewer particles from the direction of A than from the opposite direction. One can say that A and B are "shadowing" each other, and the two bodies are pushed toward each other by the resulting imbalance of forces.
This shadow obeys the inverse square law, because the imbalance of momentum flow over an entire spherical surface enclosing the object is independent of the size of the enclosing sphere, whereas the surface area of the sphere increases in proportion to the square of the radius. To satisfy the need for mass proportionality, the theory posits that a) the basic elements of matter are very small so that gross matter consists mostly of empty space, and b) that the particles are so small, that only a small fraction of them would be intercepted by gross matter. The result is, that the "shadow" of each body is proportional to the surface of every single element of matter.
Criticism: This theory was declined primarily for thermodynamic reasons because a shadow only appears in this model if the particles or waves are at least partly absorbed, which should lead to an enormous heating of the bodies. Also drag, i.e. the resistance of the particle streams in the direction of motion, is a great problem too. This problem can be solved by assuming superluminal speeds, but this solution largely increases the thermal problems and contradicts special relativity.
Vortex
Because of his philosophical beliefs, René Descartes proposed in 1644 that no empty space can exist and that space must consequently be filled with matter. The parts of this matter tend to move in straight paths, but because they lie close together, they cannot move freely, which according to Descartes implies that every motion is circular, so the aether is filled with vortices. Descartes also distinguishes between different forms and sizes of matter in which rough matter resists the circular movement more strongly than fine matter. Due to centrifugal force, matter tends towards the outer edges of the vortex, which causes a condensation of this matter there. The rough matter cannot follow this movement due to its greater inertia—so due to the pressure of the condensed outer matter those parts will be pushed into the center of the vortex. According to Descartes, this inward pressure is nothing other than gravity. He compared this mechanism with the fact that if a rotating, liquid filled vessel is stopped, the liquid goes on to rotate. Now, if one drops small pieces of light matter (e.g. wood) into the vessel, the pieces move to the middle of the vessel. This idea on the formation of the cosmos by vortices of matter was preceded by the ancient pre-Socratic atomists Leucippus and Democritus.
Following the basic premises of Descartes, Christiaan Huygens between 1669 and 1690 designed a much more exact vortex model. This model was the first theory of gravitation which was worked out mathematically. He assumed that the aether particles are moving in every direction, but were thrown back at the outer borders of the vortex and this causes (as in the case of Descartes) a greater concentration of fine matter at the outer borders. So also in his model the fine matter presses the rough matter into the center of the vortex. Huygens also found out that the centrifugal force is equal to the force that acts in the direction of the center of the vortex (centripetal force). He also posited that bodies must consist mostly of empty space so that the aether can penetrate the bodies easily, which is necessary for mass proportionality. He further concluded that the aether moves much faster than the falling bodies. At this time, Newton developed his theory of gravitation which is based on attraction, and although Huygens agreed with the mathematical formalism, he said the model was insufficient due to the lack of a mechanical explanation of the force law. Newton's discovery that gravity obeys the inverse square law surprised Huygens and he tried to take this into account by assuming that the speed of the aether is smaller in greater distance.
Criticism: Newton objected to the theory because drag must lead to noticeable deviations of the orbits which were not observed. Another problem was that moons often move in different directions, against the direction of the vortex motion. Also, Huygens' explanation of the inverse square law is circular, because this means that the aether obeys Kepler's third law. But a theory of gravitation has to explain those laws and must not presuppose them.
Several British physicists developed vortex theory of the atom in the late nineteenth century. However, the physicist, William Thomson, 1st Baron Kelvin, developed a quite distinct approach. Whereas Descartes had outlined three species of matter – each linked respectively to the emission, transmission, and reflection of light – Thomson developed a theory based on a unitary continuum.
Streams
In a 1675 letter to Henry Oldenburg, and later to Robert Boyle, Newton wrote the following: [Gravity is the result of] “a condensation causing a flow of ether with a corresponding thinning of the ether density associated with the increased velocity of flow.” He also asserted that such a process was consistent with all his other work and Kepler's Laws of Motion. Newtons' idea of a pressure drop associated with increased velocity of flow was mathematically formalised as Bernoulli's principle published in Daniel Bernoulli's book Hydrodynamica in 1738.
However, although he later proposed a second explanation (see section below), Newton's comments to that question remained ambiguous. In the third letter to Bentley in 1692 he wrote:
It is inconceivable that inanimate brute matter should, without the mediation of something else which is not material, operate upon and affect other matter, without mutual contact, as it must do if gravitation in the sense of Epicurus be essential and inherent in it. And this is one reason why I desired you would not ascribe 'innate gravity' to me. That gravity should be innate, inherent, and essential to matter, so that one body may act upon another at a distance, through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity, that I believe no man who has in philosophical matters a competent faculty of thinking can ever fall into it. Gravity must be caused by an agent acting constantly according to certain laws; but whether this agent be material or immaterial, I have left to the consideration of my readers.
On the other hand, Newton is also well known for the phrase Hypotheses non fingo, written in 1713:
I have not as yet been able to discover the reason for these properties of gravity from phenomena, and I do not feign hypotheses. For whatever is not deduced from the phenomena must be called a hypothesis; and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferred from the phenomena, and afterwards rendered general by induction.
And according to the testimony of some of his friends, such as Nicolas Fatio de Duillier or David Gregory, Newton thought that gravitation is based directly on divine influence.
Similar to Newton, but mathematically in greater detail, Bernhard Riemann assumed in 1853 that the gravitational aether is an incompressible fluid and normal matter represents sinks in this aether. So if the aether is destroyed or absorbed proportionally to the masses within the bodies, a stream arises and carries all surrounding bodies into the direction of the central mass. Riemann speculated that the absorbed aether is transferred into another world or dimension.
Another attempt to solve the energy problem was made by Ivan Osipovich Yarkovsky in 1888. Based on his aether stream model, which was similar to that of Riemann, he argued that the absorbed aether might be converted into new matter, leading to a mass increase of the celestial bodies.
Criticism: As in the case of Le Sage's theory, the disappearance of energy without explanation violates the energy conservation law. Also some drag must arise, and no process which leads to a creation of matter is known.
Static pressure
Newton updated the second edition of Optics (1717) with another mechanical-ether theory of gravity. Unlike his first explanation (1675 – see Streams), he proposed a stationary aether which gets thinner and thinner nearby the celestial bodies. On the analogy of the lift, a force arises, which pushes all bodies to the central mass. He minimized drag by stating an extremely low density of the gravitational aether.
Like Newton, Leonhard Euler presupposed in 1760 that the gravitational aether loses density in accordance with the inverse square law. Similarly to others, Euler also assumed that to maintain mass proportionality, matter consists mostly of empty space.
Criticism: Both Newton and Euler gave no reason why the density of that static aether should change. Furthermore, James Clerk Maxwell pointed out that in this "hydrostatic" model "the state of stress... which we must suppose to exist in the invisible medium, is 3000 times greater than that which the strongest steel could support".
Waves
Robert Hooke speculated in 1671 that gravitation is the result of all bodies emitting waves in all directions through the aether. Other bodies, which interact with these waves, move in the direction of the source of the waves. Hooke saw an analogy to the fact that small objects on a disturbed surface of water move to the center of the disturbance.
A similar theory was worked out mathematically by James Challis from 1859 to 1876. He calculated that the case of attraction occurs if the wavelength is large in comparison with the distance between the gravitating bodies. If the wavelength is small, the bodies repel each other. By a combination of these effects, he also tried to explain all other forces.
Criticism: Maxwell objected that this theory requires a steady production of waves, which must be accompanied by an infinite consumption of energy.
Challis himself admitted, that he hadn't reached a definite result due to the complexity of the processes.
Pulsation
Lord Kelvin (1871) and Carl Anton Bjerknes (1871) assumed that all bodies pulsate in the aether. This was in analogy to the fact that, if the pulsation of two spheres in a fluid is in phase, they will attract each other; and if the pulsation of two spheres is not in phase, they will repel each other. This mechanism was also used for explaining the nature of electric charges. Among others, this hypothesis has also been examined by George Gabriel Stokes and Woldemar Voigt.
Criticism : To explain universal gravitation, one is forced to assume that all pulsations in the universe are in phase—which appears very implausible. In addition, the aether should be incompressible to ensure that attraction also arises at greater distances. And Maxwell argued that this process must be accompanied by a permanent new production and destruction of aether.
Other historical speculations
In 1690, Pierre Varignon assumed that all bodies are exposed to pushes by aether particles from all directions, and that there is some sort of limitation at a certain distance from the Earth's surface which cannot be passed by the particles. He assumed that if a body is closer to the Earth than to the limitation boundary, then the body would experience a greater push from above than from below, causing it to fall toward the Earth.
In 1748, Mikhail Lomonosov assumed that the effect of the aether is proportional to the complete surface of the elementary components of which matter consists (similar to Huygens and Fatio before him). He also assumed an enormous penetrability of the bodies. However, no clear description was given by him as to how exactly the aether interacts with matter so that the law of gravitation arises.
In 1821, John Herapath tried to apply his co-developed model of the kinetic theory of gases on gravitation. He assumed that the aether is heated by the bodies and loses density so that other bodies are pushed to these regions of lower density.
However, it was shown by Taylor that the decreased density due to thermal expansion is compensated for by the increased speed of the heated particles; therefore, no attraction arises.
Recent theorizing
These mechanical explanations for gravity never gained widespread acceptance, although such ideas continued to be studied occasionally by physicists until the beginning of the twentieth century, by which time it was generally considered to be conclusively discredited. However, some researchers outside the scientific mainstream still try to work out some consequences of those theories.
Le Sage's theory was studied by Radzievskii and Kagalnikova (1960), Shneiderov (1961), Buonomano and Engels (1976), Adamut (1982), and Edwards (2014).
Gravity due to static pressure was recently studied by Arminjon.
See also
History of gravitational theory
Le Sage's theory of gravitation
References
Sources
Theories of gravity
Aether theories
Natural philosophy
History of physics
Obsolete scientific theories | Mechanical explanations of gravitation | [
"Physics"
] | 3,081 | [
"Theoretical physics",
"Theories of gravity"
] |
11,817,333 | https://en.wikipedia.org/wiki/Deightoniella%20torulosa | Deightoniella torulosa is an ascomycete fungus that is a plant pathogen.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Enigmatic Ascomycota taxa
Fungus species | Deightoniella torulosa | [
"Biology"
] | 50 | [
"Fungi",
"Fungus species"
] |
11,817,399 | https://en.wikipedia.org/wiki/Guignardia%20musae | Guignardia musae is a plant pathogen that causes banana freckle a disease that forms water soaked lesions of banana fruit and is spread by rain splash.
References
Fungal plant pathogens and diseases
Banana diseases
Botryosphaeriaceae
Fungi described in 1909
Fungus species | Guignardia musae | [
"Biology"
] | 56 | [
"Fungi",
"Fungus species"
] |
11,817,460 | https://en.wikipedia.org/wiki/Ramichloridium%20musae | Ramichloridium musae is an ascomycete fungus that is a plant pathogen infecting bananas.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Banana diseases
Enigmatic Ascomycota taxa
Fungus species | Ramichloridium musae | [
"Biology"
] | 55 | [
"Fungi",
"Fungus species"
] |
11,817,495 | https://en.wikipedia.org/wiki/Veronaea%20musae | Veronaea musae is an ascomycete fungus that is a plant pathogen infecting bananas.
See also
List of banana and plantain diseases
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Banana diseases
Enigmatic Ascomycota taxa
Fungus species | Veronaea musae | [
"Biology"
] | 62 | [
"Fungi",
"Fungus species"
] |
11,817,652 | https://en.wikipedia.org/wiki/Loupe | A loupe ( ) is a simple, small magnification device used to see small details more closely. They generally have higher magnification than a magnifying glass, and are designed to be held or worn close to the eye. A loupe does not have an attached handle, and its focusing lens(es) are contained in an opaque cylinder or cone. On some loupes this cylinder folds into an enclosing housing that protects the lenses when not in use.
Optics
Three basic types of loupes exist:
Simple lenses, generally used for low-magnification designs because of high optical aberration.
Compound lenses, generally used for higher magnifications to control optical aberration.
Prismatic, multiple lenses with prisms.
Uses
Loupes are used in many professions where magnification enables precision work to be done with greater efficiency and ease. Examples include surgery, dentistry, ophthalmology, the jewelry trade, gemology, questioned document examination and watchmaking. Loupes are also sometimes used in photography and printing.
Jewellers and gemologists
Jewellers typically use a monocular, handheld loupe to magnify gemstones and other jewelry that they wish to inspect. A 10× magnification is good to use for inspecting jewelry and hallmarks and is the Gemological Institute of America's standard for grading diamond clarity. Stones will sometimes be inspected at higher magnifications than 10×, although the depth of field and field of view become too small to be instructive. The accepted standard for grading diamonds is therefore that inclusions and blemishes visible at 10× impact the clarity grade. The inclusions in VVS diamonds are hard to find even at 10×.
Watchmaking
Loupes are employed to assist watchmakers in assembling mechanical watches. Many aspects require the use of the loupe, in particular the assembly of the watch mechanism itself, the assembly and details of the watch dial, as well as the formation of the watch strap and installation of precious stones onto the watch face.
Photography
Analog (film) photographers use loupes to review, edit or analyze negatives and slides on a light table. Typical magnifications for viewing slides full-frame depend on image format; 35 mm frames (24×36 mm slides to 38×38 mm superslides) are best viewed at ca. 5×, while ca. 3× is optimal for viewing medium format slides (6×4.5 cm / 6×6 cm / 6×7 cm). Often, a 10× loupe is used to examine critical sharpness. Photographers using large format cameras may use a loupe to view the ground glass image to aid in focusing. Users of digital single-lens reflex cameras use loupes to help to identify dust and other particles on the sensor, in preparation for sensor cleaning.
Dentistry
Dentists, hygienists, and dental therapists typically use binocular loupe glasses since they need both hands free when performing dental procedures. The magnification helps with accurate diagnoses of oral conditions and enhances surgical precision when completing treatment. Additionally, loupes can improve dentists' posture which can decrease occupational strain.
Some dental loupes are flip-type, which take the form of two small cylinders, one in front of each lens of the glasses. Other types are inset within the lens of the glasses.
Dental caries, also known as cavities, are most accurately identified by visual and tactile examination of a clean, dry tooth. Magnification enables dentists to improve their ability to differentiate between a stain and a cavity. Cavities are rated and scored based on their visual presentation. If magnification is too high diagnosis becomes difficult due to the small field of view. Ideal magnification for diagnostic purposes is up to 2×. Treatment of dental caries, periodontal disease, and pulpal disease are all aided by magnification.
The dental specialty of endodontics has performed the vast majority of research regarding magnification in dentistry. Because the identification of accessory canals in addition to the primary pulp canals is essential to complete nonsurgical root canal therapy, magnification provides dentists enhanced visualization to locate and treat more obscured canals.
Treatment of periodontal disease is achieved by removing calculus deposits, plaque and therefore bacteria which causes inflammation and subsequently bone destruction. In severe cases, surgery to reduce pocket depth is indicated. Periodontists and hygienists must visualize plaque and calculus to remove it. Magnification can assist dentists and hygienists with identification and removal of plaque and calculus in addition to improving visualization for periodontal surgery.
Ergonomics have long been a pain point for doctors who need to physically strain, bending over and looking down, to treat their patients. Over time this posture results in discomfort, pain, and even neuromuscular disease. Some modern loupes address this by incorporating refractive prisms which alter the course of the light through the telescopes, so that the dentist can maintain a neutral, upright position with eyes relaxed and looking straight ahead.
A typical magnification for use in dentistry is 2.5×, but dental loupes can be anywhere in the range from 2× to 8×. Optimal magnification is a function of the type of work the doctor does - namely, how much detail he or she needs to see, taking into consideration that when magnification increases, the field of view decreases. As a tool that sits on the face and is used for hours at a time, weight is also a significant factor in considering the type of loupes to use.
Together with proper access to the oral cavity, light is an important part of performing precision dentistry. Because a dentist's head often eclipses the overhead dental lamp, loupes may be fitted with a light source. Loupe-mounted lights used to be fed by fiber optic cables that connected to either a wall-mounted or table-top light source. Newer models feature a more convenient LED lamp within the loupe-mounted light and an electric cord coming from either the conventional wall-mounted or table-top light source or a belt clip rechargeable battery pack. Options for loupe-mounted cameras and video recorders are also available.
Surgery
Surgeons in many specialties commonly use loupes when doing surgery on delicate structures. The loupes used by surgeons are mounted in the lenses of glasses and are custom made for the individual surgeon, taking into account their corrected vision, interpupillary distance and desired focal distance. Multiple magnification powers are available. They are most commonly used in otolaryngology, neurosurgery, ophthalmology, plastic surgery, cardiac surgery, orthopedic surgery, and vascular surgery.
Geology
The loupe is a vital geological field tool used to identify small mineral crystals and structures in rocks.
Collectables
Loupes are an essential tool in both numismatics, the study of currency, and the related practice of coin collection. Coin collectors frequently employ loupes for better evaluation of the quality of their coins, since identifying surface wear is vital when attempting to classify the grade of a coin. Uncirculated coins (coins without wear) can command a substantial premium over coins with slight wear. This wear cannot always be seen with the naked eye. Numismatists can also employ loupes to identify some counterfeit coins that would pass a naked-eye visual inspection. Loupes are similarly used for evaluating other collectable objects, such as trading cards and antiques.
Archival conservation
Conservators often use hand held loupes or head-mounted binocular magnifiers such as the Optivisor to examine artifacts and documents requiring cleaning or repair.
See also
Bioptic telescope
Loupe light
Pocket comparator
References
External links
Dental equipment
Magnifiers
Photography equipment
Watchmaking | Loupe | [
"Technology",
"Engineering"
] | 1,609 | [
"Magnifiers",
"Measuring instruments"
] |
11,817,733 | https://en.wikipedia.org/wiki/Uredo%20musae | Uredo musae is a fungus that is a plant pathogen, infecting bananas.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Banana diseases
Enigmatic Basidiomycota taxa
Fungi described in 1941
Fungus species | Uredo musae | [
"Biology"
] | 54 | [
"Fungi",
"Fungus species"
] |
11,817,769 | https://en.wikipedia.org/wiki/Uromyces%20musae | Uromyces musae is a fungal species and plant pathogen infecting bananas.
It was found originally on the leaves of Musa species in the Democratic Republic of the Congo, Africa.
It is described as forming rusty-brown to almost black, erumpent (bursting through a surface or covering) and partially linear pustules, mostly on the lower leaf surface of the host plant.
It is found in south west Pacific region, except from the Congo and Nigeria in Africa. It is found in the Philippines, Fiji and also Wallis Island.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Banana diseases
musae
Fungi described in 1907
Fungus species | Uromyces musae | [
"Biology"
] | 139 | [
"Fungi",
"Fungus species"
] |
11,817,818 | https://en.wikipedia.org/wiki/Acrodontium%20simplex | Acrodontium simplex is an ascomycete fungus that is a plant pathogen.
References
Fungal plant pathogens and diseases
Enigmatic Ascomycota taxa
Fungi described in 1952
Fungus species | Acrodontium simplex | [
"Biology"
] | 42 | [
"Fungi",
"Fungus species"
] |
11,817,856 | https://en.wikipedia.org/wiki/Drechslera%20musae-sapientium | Drechslera musae-sapientium is a plant pathogen.
References
External links
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Pleosporaceae
Fungus species | Drechslera musae-sapientium | [
"Biology"
] | 38 | [
"Fungi",
"Fungus species"
] |
11,817,906 | https://en.wikipedia.org/wiki/Leptosphaeria%20musarum | Leptosphaeria musarum is a plant pathogen.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Pleosporales
Fungus species
Fungi described in 1889 | Leptosphaeria musarum | [
"Biology"
] | 43 | [
"Fungi",
"Fungus species"
] |
11,817,930 | https://en.wikipedia.org/wiki/Pestalotiopsis%20disseminata | Pestalotiopsis disseminata is a fungal plant pathogen infecting bananas.
References
External links
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Banana diseases
disseminata
Fungus species | Pestalotiopsis disseminata | [
"Biology"
] | 42 | [
"Fungi",
"Fungus species"
] |
11,817,955 | https://en.wikipedia.org/wiki/Haplobasidion%20musae | Haplobasidion musae, also known as the Malayan leaf spot, is an ascomycete fungus that is a plant pathogen. It was first described M. B. Ellis in 1957.
References
External links
Index Fungorum
USDA ARS Fungal Database
Enigmatic Ascomycota taxa
Fungal plant pathogens and diseases
Fungus species | Haplobasidion musae | [
"Biology"
] | 72 | [
"Fungi",
"Fungus species"
] |
11,817,965 | https://en.wikipedia.org/wiki/Air%20permeability%20specific%20surface | The air permeability specific surface of a powder material is a single-parameter measurement of the fineness of the powder. The specific surface is derived from the resistance to flow of air (or some other gas) through a porous bed of the powder. The SI units are m2·kg−1 ("mass specific surface") or m2·m−3 ("volume specific surface").
Significance
The particle size, or fineness, of powder materials is very often critical to their performance.
Measurement of air permeability can be performed very rapidly, and does not require the powder to be exposed to vacuum or to gases or vapours, as is necessary for the BET method for determination of specific surface area. This makes it both very cost-effective, and also allows it to be used for materials which may be unstable under vacuum.
When a powder reacts chemically with a liquid or gas at the surface of its particles, the specific surface is directly related to its rate of reaction. The measurement is therefore important in the manufacture of many processed materials.
In particular, air permeability is almost universally used in the cement industry as a gauge of product fineness which is directly related to such properties as speed of setting and rate of strength development.
Other fields where air permeability has been used to determine specific surface area include:
Paint and pigments
Pharmaceuticals
Metallurgical powders, including sintered metal filters.
In some fields, particularly powder metallurgy, the related Fisher number is the parameter of interest. This is the equivalent average particle diameter, assuming that the particles are spherical and have uniform size. Historically, the Fisher number was obtained by measurement using the Fisher Sub-sieve Sizer, a commercial instrument containing an air pump and pressure regulator to establish a constant air flow, which is measured using a flowmeter. A number of manufacturers make equivalent instruments, and the Fisher number can be calculated from air permeability specific surface area values.
Methods
Measurement consists of packing the powder into a cylindrical "bed" having a known porosity (i.e. volume of air-space between particles divided by total bed volume). A pressure drop is set up along the length of the bed cylinder. The resulting flow-rate of air through the bed yields the specific surface by the Kozeny–Carman equation:
where:
S is specific surface, m2·kg−1
d is the cylinder diameter, m
ρ is the sample particle density, kg·m−3
ε is the volume porosity of the bed (dimensionless)
δP is the pressure drop across the bed, Pa
l is the cylinder length, m
η is the air dynamic viscosity, Pa·s
Q is the flowrate, m3·s−1
It can be seen that the specific surface is proportional to the square root of the ratio of pressure to flow. Various standard methods have been proposed:
Maintain a constant flowrate, and measure the pressure drop
Maintain a constant pressure drop, and measure the flowrate
Allow both to vary, deriving the ratio from the characteristics of the apparatus.
Lea and Nurse method
The second of these was developed by Lea and Nurse. The bed is 25 mm in diameter and 10 mm thick. The desired porosity (which may vary in the range 0.4 to 0.6) is obtained by using a calculated weight of sample, pressed to precisely these dimensions. The required weight is given by:
A flowmeter consisting of a long capillary is connected in series with the powder bed. The pressure drop across the flowmeter (measured by a manometer) is proportional to the flowrate, and the proportionality constant can be measured by direct calibration. The pressure drop across the bed is measured by a similar manometer. Thus the required pressure/flow ratio can be obtained from the ratio of the two manometer readings, and when fed into the Carman equation, yields an "absolute" value of the air permeability surface area. The apparatus is maintained at a constant temperature, and dry air is used so that the air viscosity can be obtained from tables.
Rigden method
This was developed in the desire for a simpler method. The bed is connected to a wide-diameter u-tube containing a liquid such as kerosene. On pressurizing the space between the u-tube and the bed, the liquid is forced down. The level of liquid then acts as a measure of both pressure and volume flow. The liquid level rises as air leaks out through the bed. The time taken for the liquid level to pass between two pre-set marks on the tube is measured by stop-watch. The mean pressure and mean flowrate can be derived from the dimensions of the tube and the density of the liquid.
A later development used mercury in the u-tube: because of mercury's greater density, the apparatus could be more compact, and electrical contacts in the tube touching the conductive mercury could automatically start and stop a timer.
Blaine method
This was developed independently by R L Blaine of the American National Bureau of Standards, and uses a small glass kerosene manometer to apply suction to the powder bed. It differs from the other methods in that, because of uncertainty of the dimensions of the manometer tube, absolute results can't be calculated from the Carman equation. Instead, the apparatus must be calibrated using a known standard material. The original standards, supplied by NBS, were certified using the Lea and Nurse method. Despite this shortcoming, the Blaine method has become by far the most commonly used for cement materials, mainly because of the ease of maintenance of the apparatus and simplicity of the procedure.
See also
Klinkenberg correction
References
Chemical engineering
Particle technology | Air permeability specific surface | [
"Chemistry",
"Engineering"
] | 1,159 | [
"Particle technology",
"Chemical engineering",
"nan",
"Environmental engineering"
] |
11,817,987 | https://en.wikipedia.org/wiki/Marasmiellus%20inoderma | Marasmiellus inoderma is a fungus in the family Marasmiaceae. It is a plant pathogen that causes root-rot of maize, Marasmiellus rot on banana and basal rot of golden shower orchid.
References
Banana diseases
Maize diseases
Fungi described in 1851
Orchid diseases
Marasmiaceae
Taxa named by Miles Joseph Berkeley
Fungus species | Marasmiellus inoderma | [
"Biology"
] | 69 | [
"Fungi",
"Fungus species"
] |
11,818,020 | https://en.wikipedia.org/wiki/Marasmius%20semiustus | Marasmius semiustus is a species of fungus in the family Marasmiaceae. It is a plant pathogen responsible for banana plant disease commonly found in the West Indies. The only known remedy is the removal and burning of diseased plants.
This fungus is also found in Malaysia, Hawaii, Taiwan, and Costa Rica. It was first described scientifically in 1869.
References
Fungi of Asia
Fungi of Central America
Fungi described in 1869
Fungal plant pathogens and diseases
Banana diseases
semiustus
Taxa named by Miles Joseph Berkeley
Fungus species | Marasmius semiustus | [
"Biology"
] | 107 | [
"Fungi",
"Fungus species"
] |
11,818,055 | https://en.wikipedia.org/wiki/Phaeoseptoria%20musae | Phaeoseptoria musae is a plant pathogen infecting banana and plantain.
See also
List of banana and plantain diseases
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Banana diseases
Phaeosphaeriaceae
Fungus species | Phaeoseptoria musae | [
"Biology"
] | 57 | [
"Fungi",
"Fungus species"
] |
11,818,074 | https://en.wikipedia.org/wiki/Carr%20%28landform%29 | A carr is a type of waterlogged wooded terrain that, typically, represents a succession stage between the original reedy marsh and the likely eventual formation of forest in a sub-maritime climate. Carrs are wetlands that are dominated by shrubs rather than trees. The carr is one stage in a hydrosere: the progression of vegetation beginning from a terrain submerged by fresh water along a river or lake margin. In sub-maritime regions, it begins with reed-marsh. As the reeds decay, the soil surface eventually rises above the water, creating fens that allow vegetation such as sedge to grow. As this progression continues, riparian trees and bushes appear and a carr landscape is created – in effect a wooded fen in a waterlogged terrain. At this stage, overall, unlike the overwhelming acidity of decaying reeds, the pH is not too acidic and the soil is not too deficient in minerals, making a habitat for endemic and other wildlife. Characteristic water-tolerant trees include alder and willow.
Etymology
The word carr derives from the Old Norse kjarr, meaning "brushwood" in the word kjarr-mýrr, meaning "marsh overgrown with brushwood." Other descendants of kjarr include Icelandic kjarr "brushwood"; Norwegian kjarr, kjerr "brushwood"; Danish kær "swamp", Swedish kärr, same meaning.
References
Landforms
Wetlands
no:Sumpskogsmark
sv:Sumpskog | Carr (landform) | [
"Environmental_science"
] | 307 | [
"Hydrology",
"Wetlands"
] |
11,818,087 | https://en.wikipedia.org/wiki/Cylindrocarpon%20musae | Cylindrocarpon musae is a fungal plant pathogen that causes root rot in banana.
Infection
Infection is aided by pre-existing infection: Secondary infection by C. musae is easier after primary infection by nematodes.
References
Nectriaceae
Fungal plant pathogens and diseases
Banana diseases
Fungi described in 1974
Fungus species | Cylindrocarpon musae | [
"Biology"
] | 66 | [
"Fungi",
"Fungus species"
] |
11,818,111 | https://en.wikipedia.org/wiki/Mycosphaerella%20eumusae | Mycosphaerella eumusae is a fungal disease of banana (Musa spp.), causing Eumusae leaf spot. Its symptoms are similar to black leaf streak (Black Sigatoka, ). M. eumusae is the predominant Mycospharella of banana in mainland Malaysia and in Thailand, and is present in Mauritius and Nigeria. Septoria eumusae is an anamorph of Mycosphaerella eumusae.
References
See also
List of Mycosphaerella species
eumusae
Fungal plant pathogens and diseases
Fungi described in 2000
Fungus species | Mycosphaerella eumusae | [
"Biology"
] | 121 | [
"Fungi",
"Fungus species"
] |
11,818,173 | https://en.wikipedia.org/wiki/Nectria%20foliicola | Nectria foliicola is a fungal plant pathogen.
References
Fungal plant pathogens and diseases
foliicola
Fungi described in 1868
Fungus species | Nectria foliicola | [
"Biology"
] | 32 | [
"Fungi",
"Fungus species"
] |
11,818,219 | https://en.wikipedia.org/wiki/Mycosphaerella%20musicola | Mycosphaerella musicola (or Pseudocercospora musae,) is a fungal plant pathogen, which is the causal agent of Yellow Sigatoka leaf spot disease on banana plants.
Characteristics
Sigatoka leaf spot disease (SD) is a disease of bananas and is caused by the ascomycetous fungus, Mycosphaerella musicola. This pathogen can be distinguished morphologically from Mycosphaerella fijiensis, which causes black leaf streak disease (BLSD), by the characteristics of the conidia and conidiophore. The anamorph of M. musicola is Pseudocercospora musae which lacks the thickened cell walls that are present at the base of the conidia of Paracercospora fijien, the anamorph of M. fijiensis, and are shorter and less wavy. The conidiophores of P. musae are bottle-shaped and much smaller than the elongated conidiophores of P. fijiensis which are often bent and bear conspicuous conidial scars. The two species can also be differentiated by molecular methods.
Distribution
Mycosphaerella musicola was first reported from Java in 1902 and by 1962 was found in most banana growing regions of the world. Although it is spread over short distances by conidia and ascospores, over long distances it is the movement of infected germplasm such as diseased leaves and suckers that is likely to be responsible. In the Pacific islands and in lowland areas of South America (including Brazil,) and Africa, symptoms of SD are now rarely seen and BLSD has largely supplanted it. SD is more adapted to cooler regions and often predominates at altitudes over 1200 metres while BLSD is rarely seen at such elevations.
Life cycle
When spores of M. musicola are deposited on a susceptible banana leaf they germinate within three hours if there is a film of water present or if the humidity is very high. The optimal temperature for germination of the conidia is between 25-29 °C and for the ascospores, 25-26 °C. The germ tube grows epiphytically over the epidermis for about five days before penetrating the leaf via a stoma. Once inside the leaf the invasive hypha forms a vesicle and fine hyphae grow through the mesophyll layers into an air chamber. More hyphae then grow into the palisade tissue and continue on into other air chambers, eventually emerging through stomata in the streak that has developed. Further epiphytic growth occurs before the re-entry of the hypha into the leaf through another stoma repeats the process.
Both conidia and ascospores are important for dispersal of M. musicola with the ascospores being involved in the movement of the pathogen over longer distances than the conidia. The deposition of ascospores by wind currents is generally near the tips of the leaves resulting in a distinctive pattern of infection on the leaf extremities. When conidia are the source of the inoculum and these are dislodged by rain, a distinctive line of streaks is produced as water trickles down the leaf blade.
Symptoms
It is not always easy to differentiate between the symptoms of SD and BLSD. The first sign of disease in SD is the appearance of small yellow streaks on the upper side of leaves while in BLSD small, dark brown streaks appear on the lower surface of leaves. These streaks enlarge and coalesce forming necrotic lesions with light gray centres and yellow perimeters. Large areas of leaf can be damaged causing a lowering of photosynthetic ability, a reduction in crop yield and premature ripening of the fruit. BLSD is the more serious of the diseases as the symptoms emerge on younger leaves and it affects many cultivars that have developed resistance to SD, including the plantain subgroup.
References
External links
Index Fungorum
USDA ARS Fungal Database
Sigatoka Leaf Spot Diseases
Sigatoka Disease of Banana
musicola
Fungal plant pathogens and diseases
Banana diseases
Fungi described in 1902
Leaf diseases
Fungus species | Mycosphaerella musicola | [
"Biology"
] | 861 | [
"Fungi",
"Fungus species"
] |
11,818,323 | https://en.wikipedia.org/wiki/Limacinula%20tenuis | Limacinula tenuis is a plant pathogen infecting bananas.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Banana diseases
Capnodiales
Fungi described in 1913
Fungus species | Limacinula tenuis | [
"Biology"
] | 46 | [
"Fungi",
"Fungus species"
] |
11,818,646 | https://en.wikipedia.org/wiki/Mycosphaerella%20musae | Mycosphaerella musae is a fungal plant pathogen.
See also
List of Mycosphaerella species
References
musae
Fungal plant pathogens and diseases
Fungi described in 1917
Fungus species | Mycosphaerella musae | [
"Biology"
] | 40 | [
"Fungi",
"Fungus species"
] |
11,818,665 | https://en.wikipedia.org/wiki/Endothiella%20gyrosa | Endothiella gyrosa is a plant pathogen.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Diaporthales
Fungi described in 1906
Fungus species | Endothiella gyrosa | [
"Biology"
] | 42 | [
"Fungi",
"Fungus species"
] |
11,818,703 | https://en.wikipedia.org/wiki/Hymenochaete%20corrugata | Hymenochaete corrugata is a plant pathogen that causes glue crust in its hosts.
Hosts and symptoms
Hosts and symptoms are crucial to know when trying to identify a pathogen of disease. In order for the pathogen to be identified, its common hosts and key symptoms must be accessible. The primary hosts of Hymenochaete corrugata are broad-leaved trees, primarily hazel and willow. The disease is called glue crust and stems from the pathogen's habit of moving across trees and gluing together twigs and branches that are in contact with each other.
Common symptoms are an uneven surface caused by setae (surface hairs) and a grey or brown surface tinted lilac on the tree bark. The main sign is the presence of white fruiting bodies that form crusts attached to the trees, typically on the bark of the trunk. Setae can also be seen on the tree bark in the trunk and branches. These fruiting bodies develop cracks over time.
Environment
This disease is primarily localized to Great Britain, Ireland, mainland Europe, and parts of North America. The growing season in Europe is summer and fall. The disease development and spread is favored in woodland areas, primarily Acidophilous Quercus-dominated woodland and broadleaved deciduous woodlands. These woodland environments typically consist of summer-green non-coniferous trees and evergreen trees. These conditions are a temperate climate and are in areas with distinct seasons that make for moderate temperatures due to common rainfall.
Pathogenesis
Regarding the pathogenesis, glue crust essentially glues dead twigs to living branches in the canopy, which prevents the dead twigs from falling to the ground. If they fell to the ground, they would be available to be decomposed by other fungi. Hymenochaete corruguta’s individual genotypes can accomplish this gluing by making sclerotized mycelial pads that form a bridge binding the twigs together from various stools. The pads created can also allow for attachment to other trees, not just twigs in the same tree.
The fungus essentially can go back and forth between different modes of mycelial development and producing melanized pseudosclerotial plates, and then spreads from branch to branch through these glued-together pseudosclerotia.
References
External links
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Hymenochaetales
Fungi of Europe
Fungi described in 1846
Taxa named by Elias Magnus Fries
Fungi of North America
Fungus species | Hymenochaete corrugata | [
"Biology"
] | 502 | [
"Fungi",
"Fungus species"
] |
11,818,732 | https://en.wikipedia.org/wiki/Synchytrium%20liquidambaris | Synchytrium liquidambaris is a plant pathogen infecting sweetgum trees, that employs osmosis as a mechanism for the absorption of nutrients during the infection process.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal tree pathogens and diseases
Chytridiomycota
Fungi described in 1953
Fungus species | Synchytrium liquidambaris | [
"Biology"
] | 70 | [
"Fungus stubs",
"Fungi",
"Fungus species"
] |
11,818,756 | https://en.wikipedia.org/wiki/Cercospora%20liquidambaris | Cercospora liquidambaris is a fungal plant pathogen.
References
liquidambaris
Fungal plant pathogens and diseases
Fungus species | Cercospora liquidambaris | [
"Biology"
] | 29 | [
"Fungi",
"Fungus species"
] |
11,818,778 | https://en.wikipedia.org/wiki/Cercospora%20tuberculans | Cercospora tuberculans is a fungal plant pathogen.
References
External links
Cercospora tuberculans at JSTOR
tuberculans
Fungal plant pathogens and diseases
Taxa named by Benjamin Matlack Everhart
Fungi described in 1888
Fungus species | Cercospora tuberculans | [
"Biology"
] | 55 | [
"Fungi",
"Fungus species"
] |
11,818,799 | https://en.wikipedia.org/wiki/Wuestneiopsis%20georgiana | Wuestneiopsis georgiana is a plant pathogen.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Melanconidaceae
Fungi described in 1990
Fungus species | Wuestneiopsis georgiana | [
"Biology"
] | 43 | [
"Fungi",
"Fungus species"
] |
11,818,825 | https://en.wikipedia.org/wiki/Discosia%20artocreas | Discosia artocreas is an ascomycete fungus that is a plant pathogen.
In Iceland, it has been reported from the host species Alchemilla alpina, Betula pubescens, Geum rivale, Salix herbacea and Thalictrum alpinum.
In New Zealand, it has been reported as a host on Araucaria heterophylla and Podocarpus totara .
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Fungi of Iceland
Fungus species | Discosia artocreas | [
"Biology"
] | 113 | [
"Fungi",
"Fungus species"
] |
11,818,949 | https://en.wikipedia.org/wiki/Distributed%20economy | Distributed economies (DE) is a term that was coined by Allan Johansson et al. in 2005.
Definition
There is no official definition for DE, but it could be described as a regional approach to promote innovation by small and medium-sized enterprises, as well as sustainable development. The concept is illustrated in the figure below, that shows centralised, decentralised and distributed economies respectively.
Features
The relations in DE are much more complex than those in a centralised economy. This feature makes the whole economy more stable – leaf nodes no longer rely on just one central node. It also resembles ecological networks, making it a good practical example of industrial ecology.
A big advantage of DE is that it enables entities within the network to work much more with regional/local natural resources, finances, human capital, knowledge, technology, and so on. It also makes the entities more flexible to respond to the local market needs and thus generating a bigger innovation drive. By doing this, they become a better reflection of their social environment and in that way they can improve quality of life.
The whole concept of DE is not at all a new invention – this is how most pre-industrial economies were organised. However, information technology has opened new doors for the concept: information can be shared much more easily and small-scale production facilities (rapid prototyping) are becoming cheaper.
The DE concept works well with the development of fab labs.
Not all industries are fit for DE; for example, many chemical processes only become economically feasible & efficient on a large scale. On the other hand, bio-energy and consumer products are interesting candidates.
See also
References
External links
DeLabs - Learning Labs for Distributed Economies
DE at The International Institute for Industrial Environmental Economics at Lund University, Sweden
Economic systems
Network theory | Distributed economy | [
"Mathematics"
] | 359 | [
"Network theory",
"Mathematical relations",
"Graph theory"
] |
11,819,191 | https://en.wikipedia.org/wiki/Apiognomonia%20errabunda | Apiognomonia errabunda is a fungal plant pathogen and causal agent of oak anthracnose. It is one of the most widespread leaf-associated fungi in the northern temperate zone and is found mostly on oak, beech, and linden trees.
References
External links
Index Fungorum
USDA ARS Fungal Database
Gnomoniaceae
Fungal tree pathogens and diseases
Fungi described in 1918
Fungus species | Apiognomonia errabunda | [
"Biology"
] | 84 | [
"Fungi",
"Fungus species"
] |
11,819,233 | https://en.wikipedia.org/wiki/Apiognomonia%20veneta | Apiognomonia veneta is a plant pathogen which causes anthracnose on London Plane trees.
References
External links
USDA ARS Fungal Database
Fungal tree pathogens and diseases
Gnomoniaceae
Fungi described in 1920
Fungus species | Apiognomonia veneta | [
"Biology"
] | 50 | [
"Fungi",
"Fungus species"
] |
11,819,346 | https://en.wikipedia.org/wiki/Sphaerella%20platanifolia | Sphaerella platanifolia is a fungal plant pathogen infecting plane trees.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal tree pathogens and diseases
Mycosphaerellaceae
Fungus species | Sphaerella platanifolia | [
"Biology"
] | 45 | [
"Fungi",
"Fungus species"
] |
11,819,382 | https://en.wikipedia.org/wiki/Mycosphaerella%20polymorpha | Mycosphaerella polymorpha is a fungal plant pathogen.
See also
List of Mycosphaerella species
Fungal plant pathogens and diseases
polymorpha
Fungi described in 1941
Fungus species | Mycosphaerella polymorpha | [
"Biology"
] | 43 | [
"Fungi",
"Fungus species"
] |
11,819,421 | https://en.wikipedia.org/wiki/Stigmella%20platani-racemosae | Stigmella platani-racemosae is an ascomycete fungus that is a plant pathogen infecting plane trees.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal tree pathogens and diseases
Enigmatic Ascomycota taxa
Fungus species | Stigmella platani-racemosae | [
"Biology"
] | 58 | [
"Fungi",
"Fungus species"
] |
11,819,460 | https://en.wikipedia.org/wiki/Splanchnonema%20platani | Splanchnonema platani is a fungus in the genus Splanchnonema. It was formerly known under the name Massaria platani. The anamorph of the fungus is known as Macrodiplodiopsis desmazieresii. The fungus has caused serious damage to plane trees across Europe.
Massaria disease
The disease, commonly known as Massaria disease, infects branches of plane trees. The fungus has usually been considered to be a weak parasite causing only minor damage such as twig dieback in warmer Mediterranean climates. However, in the 21st century it has been found associated with branch death and rapid decay within other parts of Europe, most notably Germany and Austria, the Netherlands, and parts of France. Damage caused by this fungus has been reported in the southern United States. The first formal identification of the disease in the United Kingdom came in March 2011.
The disease seems to be specific to London plane, Oriental plane and American plane. The disease causes large lesions on the upper sides of branches associated with branch drop.
References
External links
Massaria disease, Forestry Commission
Massaria disease of plane trees, Treetree
Fungal tree pathogens and diseases
Pleosporales
Fungus species | Splanchnonema platani | [
"Biology"
] | 245 | [
"Fungi",
"Fungus species"
] |
11,819,519 | https://en.wikipedia.org/wiki/Phomopsis%20scabra | Phomopsis scabra is a fungal plant pathogen infecting plane trees.
External links
USDA ARS Fungal Database
Fungal tree pathogens and diseases
scabra
Fungus species | Phomopsis scabra | [
"Biology"
] | 37 | [
"Fungi",
"Fungus species"
] |
11,819,539 | https://en.wikipedia.org/wiki/Phoma%20scabra | Phoma scabra is a fungal plant pathogen infecting plane trees.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal tree pathogens and diseases
scabra
Fungi described in 1881
Fungus species | Phoma scabra | [
"Biology"
] | 45 | [
"Fungi",
"Fungus species"
] |
11,819,695 | https://en.wikipedia.org/wiki/Inonotus%20munzii | Inonotus munzii is a plant pathogen that causes wood rot on Platanus species.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal tree pathogens and diseases
munzii
Fungi described in 1969
Fungus species | Inonotus munzii | [
"Biology"
] | 48 | [
"Fungi",
"Fungus species"
] |
11,819,823 | https://en.wikipedia.org/wiki/Kluyveromyces%20lactis | Kluyveromyces lactis is a Kluyveromyces yeast commonly used for genetic studies and industrial applications. Its name comes from the ability to assimilate lactose and convert it into lactic acid.
Kluyveromyces lactis (formerly Saccharomyces lactis) is a yeast which has the ability to assimilate lactose and convert it into lactic acid. K. lactis and other organisms i.e., Aspergillus niger var awamori and Escherichia coli K-12 are grown in fermenters to produce chymosin (rennet) on a commercial scale; this rennet, which replaces the conventional form obtained from slaughtered animals, is now widely used in cheese production.
Yeasts and fungi are ideal organisms for comparative genomic studies in eukaryotes because of their small and compact genomes and because they include a number of species such as Neurospora crassa, Saccharomyces cerevisiae and Schizosaccharomyces pombe, that have been, and continue to be, used extensively in genetic studies. However, the divergence between these three species is ancient (estimated to be at least 300 million years old) and the organization of their genomes is quite different. The diversity of the hemiascomycetes, a group of ascomycetes that contains most of the known yeast species, was first explored in 2000.
Complete sequencing and comparison of four hemiascomycetous yeasts has been undertaken for Nakaseomyces glabratus, Kluyveromyces lactis, Debaryomyces hansenii, and Yarrowia lipolytica. They were selected on the basis of their phylogenetic positions and their specific interest as human pathogens, or as industrially or environmentally important yeasts. This work, which represents the first multispecies exploration of genome evolution across an entire eukaryotic phylum, reveals the variety of events and mechanisms that have taken place, and should allow useful comparisons with other phyla of multicellular organisms when more genome sequences are determined.
K. lactis is a heterothallic species with a predominantly haplontic cycle, in contrast to S. cerevisiae in which the predominantly diplobiontic cycle is pseudo-heterothallic due to mating-type switching.
Genomics analysis
In the 1990s, few genes were known and analysed by scientists until the first genomic analysis was performed by a team of the Pasteur Institute of Paris. The genome Kluyveromyces lactis was explored by sequencing 588 short tags from two random genomic libraries (random sequenced tags, or RSTs). 296 K. lactis genes were identified of which 292 were new.
The complete genome of K. lactis was sequenced in 2004.
This species has roughly 5,300 genes spread out over six nuclear chromosomes and its mitochondrial genome. The six chromosomes are labeled A-F.
References
Saccharomycetaceae
Fungi in cultivation
Fungus species | Kluyveromyces lactis | [
"Biology"
] | 637 | [
"Fungi",
"Fungus species"
] |
11,819,900 | https://en.wikipedia.org/wiki/Postia%20tephroleuca | Postia tephroleuca, also known as greyling bracket, is a species of fungus in the family Fomitopsidaceae infecting broad-leaved trees, typically beech and plane.
References
Fungi described in 1821
Fungal plant pathogens and diseases
Fomitopsidaceae
Taxa named by Elias Magnus Fries
Fungus species | Postia tephroleuca | [
"Biology"
] | 68 | [
"Fungi",
"Fungus species"
] |
11,819,940 | https://en.wikipedia.org/wiki/Septoria%20liquidambaris | Septoria liquidambaris is a fungal plant pathogen infecting sweetgum trees.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal tree pathogens and diseases
Fungus species
liquidambaris | Septoria liquidambaris | [
"Biology"
] | 44 | [
"Fungi",
"Fungus species"
] |
11,819,978 | https://en.wikipedia.org/wiki/Stigmina%20liquidambaris | Stigmina liquidambaris is a fungal plant pathogen infecting sweetgum trees.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal tree pathogens and diseases
Capnodiales
Fungi described in 1972
Fungus species | Stigmina liquidambaris | [
"Biology"
] | 49 | [
"Fungi",
"Fungus species"
] |
11,820,034 | https://en.wikipedia.org/wiki/Berthelot%27s%20reagent | Berthelot's reagent is an alkaline solution of phenol and hypochlorite, used in analytical chemistry. It is named after its inventor, Marcellin Berthelot. Ammonia reacts with Berthelot's reagent to form a blue product which is used in a colorimetric method for determining ammonia. The reagent can also be used for determining urea. In this case the enzyme urease is used to catalyze the hydrolysis of urea into carbon dioxide and ammonia. The ammonia is then determined with Berthelot's reagent.
Variations
Phenol in the Berthelot reagent can be replaced by a variety of phenolic reagents, the most common being sodium salicylate, which is significantly less toxic. This has been used for blood urea nitrogen (BUN) determinations and commonly is used to determine water and soil total and ammonia-N. Replacement of phenol by 2-phenylphenol reduces interferences by a variety of soil and water constituents and improves color stability at slightly lower pH.
Uses
Berthelot's reagent has been used in a range of situations. It is often used in colorimetric methods, through an AutoAnalyzer, spectrophotometer, or multiwell plate spectrophotometer. The reagent lacks sensitivity in situations where there may be amines as well as ammonia, however this can be overcome in part by the use of 2-phenylphenol to replace phenol. An ion selective electrode, or distillation/titration method can often be used in cases where Berthelot chemistry is ineffective.
Berthelot chemistry has also been adapted for the analysis of nitrite and nitrate in soil and water after conversion, typically by reduction with Devarda's alloy, of these species to ammonium.
References
Further reading
Dorland's Medical Dictionary
Chemical tests | Berthelot's reagent | [
"Chemistry"
] | 408 | [
"Chemical tests",
"Analytical chemistry stubs"
] |
11,820,052 | https://en.wikipedia.org/wiki/Dicarpella%20dryina | Dicarpella dryina is a species of fungus. It is a plant pathogen.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Melanconidaceae
Fungus species | Dicarpella dryina | [
"Biology"
] | 45 | [
"Fungi",
"Fungus species"
] |
11,820,124 | https://en.wikipedia.org/wiki/Ceriporia%20xylostromatoides | Ceriporia xylostromatoides is a species of fungus in the family Irpicaceae. It is a plant pathogen.
References
Fungi described in 1843
Fungal plant pathogens and diseases
Irpicaceae
Taxa named by Miles Joseph Berkeley
Fungus species | Ceriporia xylostromatoides | [
"Biology"
] | 51 | [
"Fungi",
"Fungus species"
] |
11,820,195 | https://en.wikipedia.org/wiki/Climacodon%20pulcherrimus | Climacodon pulcherrimus is a species of tooth fungus in the family Phanerochaetaceae. It was first described as a species of Hydnum by Miles Berkeley and Moses Ashley Curtis in 1849. T.L. Nikolajeva transferred it to its current genus Climacodon in 1962, but research published in 2007 suggests it should be placed in a different genus. It is widely distributed in subtropical and tropical areas, where it grows on decomposing hardwoods, causing a white rot.
References
Fungi described in 1849
Fungi of North America
Fungal plant pathogens and diseases
Phanerochaetaceae
Taxa named by Miles Joseph Berkeley
Fungus species | Climacodon pulcherrimus | [
"Biology"
] | 137 | [
"Fungi",
"Fungus species"
] |
11,820,233 | https://en.wikipedia.org/wiki/Climacodon%20septentrionalis | Climacodon septentrionalis, commonly known as the northern tooth fungus or the white rot fungus, is a species of shelf fungus in the phylum Basidiomycota. It is white in color and can be found in large clusters on the trunks of trees. This species is a plant pathogen native to North America.
Taxonomy
Climacodon septentrionalis was originally described by Elias Magnus Fries in 1821 under the genus Hydnum. It was later transferred to Climacodon in 1881 by Petter Karsten.
Description
Individual caps are semicircular or kidney-shaped and can reach up to 30 cm across and 2.5-5.0 cm at the base. They typically occur in large groups that can reach 80 cm in height. Young caps range from mostly white to a yellow-cream color, and slowly become a yellow-brown as they age. Although, the caps tend to persist for multiple weeks, allowing algae to grow, giving them a slightly green appearance. The surface of the cap can be rough or even hairy, and can have concentric rings radiating out from the base. The underside of the cap has many white spines (see left) that reach 1 cm in length and also yellow with age. C. septentrionalis is edible but not palatable due to its tough flesh and bitter taste. They can be found in the summer months and are a common cause of heart rot in hardwood trees in their native range.
Habitat and distribution
This species is native to northeastern North America, ranging from southern Canada to Kentucky, and as far west as the Great Plains. C. septentrionalis is found on the trunks of living and recently deceased trees, especially beech (Fagus) and maple (Acer) species.
Nematode predation
Climacodon septentrionalis was the first observed species fungus not in the genus Agaricus to secrete a toxin that it uses to immobilize and kill fungiphagous nematodes. The mycelium of this species grows secretory cells the protrude outwards and develop branches that produce the substance in small droplets. When a nematode comes in contact with a droplet, they become encased in it, and their motion is completely inhibited. Death after contact occurs within several hours, but the rate at which a nematode was decomposed varied greatly, ranging from a few weeks to several days.
Novel compounds
Climacodon septentrionalis has been found to produce a few different compounds that have potential to be used for a variety of products. Esters are natural or synthetic, fragrant compounds that can be found in perfumes and flavorings, or used in paints, solvents, insecticides, and more. The mycelium of this species produces esters that could be used in perfumes. The compound furaneol is a commonly used in the cooking industry as a flavoring, with different forms having tastes ranging from a strawberry or pineapple to a caramel or honey flavor. The furaneol found in C. septentrionalis is extracted from its fruiting bodies, and has a strawberry-like flavor and taste.
References
Fungi described in 1821
Fungal plant pathogens and diseases
Inedible fungi
Phanerochaetaceae
Taxa named by Elias Magnus Fries
Fungus species | Climacodon septentrionalis | [
"Biology"
] | 679 | [
"Fungi",
"Fungus species"
] |
11,820,256 | https://en.wikipedia.org/wiki/The%20Nine%20Planets | The Nine Planets is a multimedia website by Bill Arnett containing information about the Solar System. It was one of the first examples of a multimedia website when it first appeared on the World Wide Web in 1994 and, as was common for high traffic websites at the time, it was widely mirrored. It contains encyclopedic information about the Solar System with a page for each of the major bodies illustrated with photographs, mostly from NASA.
Awards
The site's numerous awards include:
1995 PC Magazine's Top 100 websites
2002 Scientific American's Sci/Tech web award for astronomy and astrophysics
References
External links
Astronomy websites
Internet properties established in 1994 | The Nine Planets | [
"Astronomy"
] | 131 | [
"Works about astronomy",
"Astronomy websites"
] |
11,820,310 | https://en.wikipedia.org/wiki/Coriolopsis%20floccosa | Coriolopsis floccosa is a fungal plant pathogen.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Polyporaceae
Fungus species | Coriolopsis floccosa | [
"Biology"
] | 39 | [
"Fungi",
"Fungus species"
] |
11,820,375 | https://en.wikipedia.org/wiki/Ceratocystis%20coerulescens | Ceratocystis coerulescens is an ascomycete fungus and the causal agent of sapstreak disease in sugar maple trees. There is debate about whether it is one species or two; the second being Ceratocystis virescens. For simplicity, this page will refer to this pathogen as one species. It is also known by its anamorph name Endoconidiophora virescens.
Host and symptoms
This fungus is often found as a saprophyte on logs of woody species. It causes sapstreak disease in just one host species: Acer saccharum, commonly known as the sugar maple or rock maple. Symptoms include a sparse crown, dieback, dwarfed leaves, and cankers. Infected trees may die suddenly or languish for 2–4 years. The symptom most characteristic of sapstreak disease is yellowish-green stained wood that is also very moist. Once the wood is cut and dries, the stains turn light brown, so they're difficult to see and diagnose at that point.
Disease cycle
As an ascomycete, Ceratocystis coerulescens produces ascospores encased as groups of eight in asci. The asci are protected by a perithecium, a flask-shaped ascocarp, in which the pathogen overwinters. Ascospores are the sexual spores and are far less common than the asexual spores known as conidia. The conidia form on conidiophores without a sporocarp. C. coerulescens has two mating types referred to as Mat-1 and Mat-2, but it is not a strictly heterothallic species. The Mat-1 type is self-sterile and must cross with Mat-2 to produce perithecia. However, the Mat-2 type is self-fertile and half of the progeny from a Mat-2 selfing are Mat-1.
Environment
Sapstreak disease has occurred only in North America and primarily in sugar bushes, stands of Acer saccharum that are tapped for maple sap. There has been a single report of it in Ontario, Canada; and cases in the U.S. have been from California, Michigan, Minnesota, New York, North Carolina, Vermont, and Wisconsin. As with all fungi, it requires a moist environment to sporulate.
Pathogenesis
Ceratocystis coerulescens enters its host through wounds, especially wounds in buttress roots and lower trunk. All diseased trees have been found to have man-made wounds from tapping and/or driving and dragging logs over them. Therefore, it's believed that the trees successfully combat the pathogen when it enters wounds higher up made by animals, insects, or weather. Sapstreak disease is commonly associated with the presence of opportunistic fungi Armillaria and/or Xylaria.
Importance
Sapstreak threatens maple syrup production primarily, but also ruins the wood for making lumber. The economic and environmental damage due to this pathogen is currently meager. Most instances have occurred after incautious logging and have been well contained. Usually a single tree or a small group is affected.
Management
The best way to manage this disease is to prevent it by avoiding injuries to the roots and lower stems of sugar maples. This can be accomplished by using the same, well-placed trails every year through the sugar bush and by using tubing systems instead of buckets to collect sap. When infection does occur, the tree should be cut down and the wood promptly removed to reduce inoculum.
References
External links
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Microascales
Fungi described in 1950
Fungus species | Ceratocystis coerulescens | [
"Biology"
] | 776 | [
"Fungi",
"Fungus species"
] |
11,820,421 | https://en.wikipedia.org/wiki/Graphium%20rigidum | Graphium rigidum is a species of fungus in the family Microascaceae. It is a plant pathogen. The fungus was originally described as new to science in 1794 by Christiaan Hendrik Persoon, as Stilbum rigidum. Pier Andrea Saccardo transferred it to the genus Graphium in 1886.
References
Fungal plant pathogens and diseases
Microascales
Fungi described in 1794
Taxa named by Christiaan Hendrik Persoon
Fungus species | Graphium rigidum | [
"Biology"
] | 94 | [
"Fungi",
"Fungus species"
] |
11,820,442 | https://en.wikipedia.org/wiki/Graphium%20rubrum | Graphium rubrum is a plant pathogen.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Microascales
Fungus species | Graphium rubrum | [
"Biology"
] | 35 | [
"Fungi",
"Fungus species"
] |
11,820,466 | https://en.wikipedia.org/wiki/Leptographium%20microsporum | Leptographium microsporum is a species of fungus in the family Ophiostomataceae. It is a plant pathogen.
References
Fungal plant pathogens and diseases
Fungi described in 1935
Ophiostomatales
Fungus species | Leptographium microsporum | [
"Biology"
] | 50 | [
"Fungi",
"Fungus species"
] |
11,820,512 | https://en.wikipedia.org/wiki/Ceratocystis%20pilifera | Ceratocystis pilifera is a fungal plant pathogen. It has been shown to be transmitted via soil in a Pinus sylvestris dominated forest in Poland.
References
Fungal plant pathogens and diseases
Microascales
Fungi described in 1952
Fungi of Poland
Fungus species | Ceratocystis pilifera | [
"Biology"
] | 58 | [
"Fungi",
"Fungus species"
] |
11,820,554 | https://en.wikipedia.org/wiki/Ceratocystis%20pluriannulata | Ceratocystis pluriannulata is a fungal plant pathogen.
References
Fungal plant pathogens and diseases
Fungi described in 1952
Microascales
Fungus species | Ceratocystis pluriannulata | [
"Biology"
] | 35 | [
"Fungi",
"Fungus species"
] |
11,820,613 | https://en.wikipedia.org/wiki/Helicoma%20muelleri | Helicoma muelleri is a fungal plant pathogen.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Tubeufiaceae
Fungus species | Helicoma muelleri | [
"Biology"
] | 36 | [
"Fungi",
"Fungus species"
] |
11,820,625 | https://en.wikipedia.org/wiki/Tyromyces%20calkinsii | Tyromyces calkinsii is a plant pathogen infecting sweetgums.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal tree pathogens and diseases
Polyporaceae
Fungus species | Tyromyces calkinsii | [
"Biology"
] | 43 | [
"Fungi",
"Fungus species"
] |
11,820,659 | https://en.wikipedia.org/wiki/Trichaptum%20sector | Trichaptum sector is a plant pathogen infecting sweetgum trees.
References
Fungal tree pathogens and diseases
Hymenochaetales
Fungi described in 1820
Fungus species | Trichaptum sector | [
"Biology"
] | 37 | [
"Fungus stubs",
"Fungi",
"Fungus species"
] |
11,820,705 | https://en.wikipedia.org/wiki/Perenniporia%20fraxinea | Perenniporia fraxinea is a species of poroid fungus in the family Polyporaceae. It is a plant pathogen infecting ash trees.
See also
List of sweetgum diseases
References
Fungal tree pathogens and diseases
Perenniporia
Fungi described in 1790
Fungi of Europe
Fungus species | Perenniporia fraxinea | [
"Biology"
] | 61 | [
"Fungi",
"Fungus species"
] |
11,820,772 | https://en.wikipedia.org/wiki/Pleurotus%20dryinus | Pleurotus dryinus, commonly known as the veiled oyster mushroom, is a species of fungus in the family Pleurotaceae. It grows on dead wood and is also a weak pathogen; infecting especially broad-leaved trees.
Naming
The species name is a Latinised version of the Greek word "dryinos" (δρύῐνος), meaning "related to oak", which refers to one of its main hosts.
The original definition of this fungus as Agaricus dryinus was made by Persoon in 1800. In 1871 in his "Führer in die Pilzkunde" ("Guide to mycology"), Paul Kummer introduced Pleurotus as a genus and defined three similar ringed species: Pleurotus corticatus, Pleurotus Albertini and P. dryinus. They were distinguished because only P. corticatus has intertwined ("anastomosing") gills on the stem and P. Albertini is bigger and grows on conifer wood rather than oak. However, nowadays all three are considered to be forms of the same species. The name dryinus takes precedence because it is the oldest.
Also, in 1874 Fries defined a species Pleurotus tephrotrichus, having a deeper grey colour, which again has been incorporated into P. dryinus but may be distinguished as the variety P. dryinus var. tephrotrichus.
The English name "Veiled Oyster Mushroom" has been given to this species.
Description
The following sections use the given references throughout.
General
The cap, growing to about 13 cm, is pale, beige or (in variety tephrotrichus) greyish; later it can turn yellowish. Veil remnants may adhere to the edge. At first it is velvety (tomentose) and the tomentum can develop into grey-brown scales; in old specimens the surface becomes bare and may crack.
The whitish or pale brownish lateral stem may be very short or up to about 8 cm long, generally with a membranous ring.
The gills are decurrent well down the stipe and may anastomose (criss-cross) at the lower extreme. They are white or cream.
The smell is described as "pleasant" or "slightly polypore-like" or "complex, a bit fruity or sourish". The odour is definitely not floury (which can be used to distinguish from P. calyptratus). The taste is mild.
Microscopic characteristics
The flesh may be monomitic (as with ordinary fragile mushrooms) but it may also be dimitic, having extra thick-walled hyphae which give the flesh a tough consistency.
The elongated spores in the form of a rounded cylinder are around 9-15 μm by 3-5 μm.
There are no cystidia.
Distribution, habitat & ecology
This mushroom is saprobic on dead wood and can also be a weak parasite of trees. It occurs especially on oak (from which it derives its name), but also on beech, other broad-leaved trees, and occasionally on conifers. It is often solitary or may grow in small groups.
Appearing from summer to autumn, it is distributed throughout Europe, where it varies locally between common and rare. It is also found in North America.
Similar species and varieties
In the following table, Species Fungorum is a general reference for the names.
Human impact
This mushroom is edible, though it is tough when older and inferior to the better-known Pleurotus species.
It is a mild parasite of broad-leaved trees (a "white rot").
Like some other Pleurotus species, P. dryinus attacks nematodes and may provide a control method for these parasites when they infect cats and dogs.
References
External links
Fungal tree pathogens and diseases
Fungi described in 1800
Pleurotaceae
Carnivorous fungi
Edible fungi
Taxa named by Christiaan Hendrik Persoon
Fungus species | Pleurotus dryinus | [
"Biology"
] | 826 | [
"Fungi",
"Fungus species"
] |
11,820,807 | https://en.wikipedia.org/wiki/Gloeocystidiellum%20porosum | Gloeocystidiellum porosum is a fungal plant pathogen. It is a corticioid homobasidiomycete that grows on various types of dead wood.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Russulales
Fungi described in 1931
Fungus species | Gloeocystidiellum porosum | [
"Biology"
] | 67 | [
"Fungi",
"Fungus species"
] |
11,820,846 | https://en.wikipedia.org/wiki/Inonotus%20ludovicianus | Inonotus ludovicianus is a species of fungus in the family Hymenochaetaceae. A plant pathogen, it is found in the southwestern United States and Louisiana.
References
Fungi described in 1908
Fungi of North America
Fungal plant pathogens and diseases
ludovicianus
Fungus species | Inonotus ludovicianus | [
"Biology"
] | 62 | [
"Fungi",
"Fungus species"
] |
11,820,876 | https://en.wikipedia.org/wiki/Lentinus%20tigrinus | Lentinus tigrinus is a mushroom in the Polyporaceae family. It is classified as nonpoisonous. It has been reported that mushrooms have significant antioxidant and antimicrobial activity.
References
Further reading
Fungal plant pathogens and diseases
Polyporaceae
Fungi of Europe
Taxa named by Jean Baptiste François Pierre Bulliard
Fungus species | Lentinus tigrinus | [
"Biology"
] | 71 | [
"Fungi",
"Fungus species"
] |
11,820,903 | https://en.wikipedia.org/wiki/Sarcodontia%20unicolor | Sarcodontia unicolor is a species of polypore fungus in the family Meruliaceae. It is a plant pathogen that affects oak trees. The fungal hyphae grow inside the tree, rotting the heartwood. The fruit bodies are initially whitish to buff in color before turning brownish in age. The pores on the underside of the cap are circular to angular. Spores are held in tubes and are ovoid to ellipsoid, with dimensions of 7–9 by 6–7 μm.
References
Fungi described in 1822
Fungi of North America
Fungal tree pathogens and diseases
Meruliaceae
Fungus species | Sarcodontia unicolor | [
"Biology"
] | 127 | [
"Fungi",
"Fungus species"
] |
11,820,942 | https://en.wikipedia.org/wiki/Steccherinum%20ochraceum | Steccherinum ochraceum, known as ochre spreading tooth, is a hydnoid fungus of the family Steccherinaceae. It is a plant pathogen infecting sweetgum trees. It can also be found in Nepal. It was originally described as Hydnum ochraceum by Johann Friedrich Gmelin in 1792, and later transferred to the genus Steccherinum by Samuel Frederick Gray in 1821.
References
Fungi described in 1792
Fungal tree pathogens and diseases
Steccherinaceae
Taxa named by Christiaan Hendrik Persoon
Fungus species | Steccherinum ochraceum | [
"Biology"
] | 119 | [
"Fungi",
"Fungus species"
] |
11,820,971 | https://en.wikipedia.org/wiki/NamibRand%20Nature%20Reserve | The NamibRand Nature Reserve is a private nature reserve in Southwestern Namibia in the Namib Desert. Founded in 1984 by J.A. (Albi) Brückner, it has more than and shares a 100 km border with Namib-Naukluft National Park to the west and the Nubib mountains to the east. It is financially self-sustaining mainly through low impact tourism fees.
In 2012, the International Dark-Sky Association designated this as an International Dark-Sky Reserve.
References
External links
Nature reserves in Namibia
International Dark Sky Reserves | NamibRand Nature Reserve | [
"Astronomy"
] | 113 | [
"International Dark Sky Reserves",
"Dark-sky preserves"
] |
7,172,328 | https://en.wikipedia.org/wiki/Plummer%20Terrier | The Plummer Terrier is a working terrier. It was originally bred by Brian Plummer to primarily be a ratter and hunt vermin. The breed, while unrecognized by any kennel club, is known for its rugged determination and hardiness.
Origins and history
In the late 1960s and throughout the 1970s, Brian Plummer worked as a somewhat reluctant teacher of several schools throughout southern Yorkshire and the Midlands. He was already well known in his local neighborhood for going around with a pack of terriers to catch rats, when he decided to create his own terrier breed in the 1970s. Well-versed in breeding, he strove to produce a unique strain of terrier by mixing the Jack Russell Terrier with the Beagle, Fell Terrier, and Bull Terrier.
These terriers were worked hard and as the breed developed, so too did Plummer's reputation as a breeder of hardy terriers that bred true to type. Initially known as the Huddlesford Rat Pack, the breed is now named after him.
The Beagle introduced to Plummer's lines in the 1960s was out of Catherine Sutton's Rossut show-bred strain that originated from U.S. imports, brought to the U.K. to tidy up British exhibits. It was owned by Philip Ainsley, a fellow teacher friend of Plummer's.
Further outcrosses were introduced along the way. The addition of Fell Terrier blood, Jaeger from Nigel Hinchcliffe's lines and Flint from Brian Nuttall's lines, both noted working lines and most likely descending from Cyril Breay and Frank Buck's stock, infused refinement of shape and to a certain extent contributed to fixing type, like that seen in Pagan, a black and tan terrier, acknowledged as one of the early pillars of the breed.
Further additions included a Jack Russell terrier known as Errol Forsyth's Pip, Alan Thomas's Hamish, and Laddie from the Chiddingfold and Leconfield foxhound kennels. Performance as an earth dog was and is an essential prerequisite of most, if not all terrier breeds and Plummers are no exception to this rule. These three dogs were known to be full-on earth workers.
In the early 1980s, during one of the many TV documentaries (Rat hunting man and Lone furrow) about Plummer and his terriers, he said that one day he would like his terriers to be known as Plummer Terriers and recognised by the Kennel Club.
In 1985, he suffered a near-fatal heart attack which resulted in the dispersal of his substantial pack of terriers to friends. He eventually moved to a remote croft in Caithness, Scotland, and began to write full-time. By the early 1990s most of the pack's important gene pool was found and regrouped, albeit on a smaller scale. Work continued and other lines were sought; widening the gene pool enough to be able to limit inbreeding.
At this point, two distinct types began to develop, the smaller, more snipe-nosed type and the more bully, stronger-headed type. Plummer opted for the latter, and by the late 1990s decided that the breed needed a wider gene pool in order to reach its maximum potential. Bull Terrier blood of known ancestry was sought and outcrossed into the breed.
Plummer had cancer and died in September 2002. His work was carried on by others and the breed standard remains intact.
As a working terrier, the Plummer is a versatile dog, which has many uses. They are keen retrievers, most generally take to water freely; quite intelligent, have excellent noses, are biddable and have many uses in the field. They are often found ferreting; some are found in the beating line on local shoots; occasionally they are used to ground but undoubtedly they are most commonly used in a pack hunting rats.
Appearance
The Plummer Terrier has a fiery red coat with two distinct patterns collared (a white band around the neck) and caped (only showing white on the throat). They should be heavily coloured and preferably be no more than 14” at the shoulder. Terriers that do not possess collared or caped markings are labelled shattered, they are perfectly fine as workers, companions but are not classed as good examples of the breed. The same can be said for tricolours, dogs which carry black in their colouring. The ears fold over like most terriers, and the nose and eye are typically black, and the jaw has a good scissors bite.
Breed standard
Plummer defined a breed standard in 2000.
Future
Generally a game working dog, the Plummer Terrier is not a Kennel Club breed, and most owners today who work their dogs would prefer that this dog was not part of the Kennel Club yet for a myriad of reasons. While the Plummer Terrier generally breeds true in appearance, the standard is a working terrier standard.
See also
Dogs portal
Ratter (dog)
List of dog breeds
Further Reading
Marcus, Lankford. (2021). Plummer Terrier Dog: Things You Need to Know About Plummer Terrier Dog: Learn Everything About Plummer Terrier Dog. Amazon Digital Services LLC - KDP Print US.
References
External links
Plummer Terrier Club of Great Britain
YouTube: Ratting With Plummer Terriers
Plummer Terrier Dog Breed: Amazing facts You Need To Know About This Terrier
Dog breeds originating in England
Pest control
Terriers | Plummer Terrier | [
"Biology"
] | 1,132 | [
"Pests (organism)",
"Pest control"
] |
7,172,719 | https://en.wikipedia.org/wiki/Evodiamine | Evodiamine is a chemical compound extracted from the plant genus Tetradium, which has been shown to reduce fat uptake in mouse studies. It is suspected that its mechanism of action is similar to that of capsaicin. As such, it has been included in some dietary supplements. Neither its fat-burning effects in humans nor any potential side effects have been empirically established.
Evodiamine acts primarily as a thermogenic and stimulant.
Evodiamine may also act by increasing the number of serotonin transporters available in the brain, enhancing the reuptake of serotonin.
References
Stimulants
Lactams
Nitrogen heterocycles
Indole alkaloids | Evodiamine | [
"Chemistry"
] | 147 | [
"Alkaloids by chemical classification",
"Indole alkaloids"
] |
7,172,777 | https://en.wikipedia.org/wiki/Isocaudomer | Isocaudomers are pairs of restriction enzymes that have slightly different recognition sequences, but upon cleavage of DNA, generate identical overhanging termini sequences. These sequences can be ligated to one another, but then form an asymmetrical sequence that cannot be cleaved by a restriction enzyme.
Examples
For example the enzymes Mbo I and BamH I are isocaudomers:
Mbo I
N*GATC N
N CTAG*N
BamH I
G*GATC C
C CTAG*G
N represents any of the four nucleotides. Independently of which nucleotide is present when cleaving with MboI, after cleavage with either enzyme, all termini have the central tetranucleotide - GATC. This allows fragments generated with one enzyme to anneal with fragments generated with the other enzyme. This can be used for elimination of restriction sites from the resulting DNA fragment. For example:
Not I
GC*GGCC GC
CG CCGG*CG
Bsp120 I
G*GGCC C
C CCGG*G
In the above example, both enzymes produce tetranucleotides CCGG which can anneal to one another. However, resulting DNA sequence will be:
GCGGCCC
CGCCGGG
where the nucleotides shown in italic originate from NotI-cut site, and those in bold from Bsp120I-cut one. Note that the resulting sequence is not recognised by either of the two enzymes.
Other examples of isocaudomers include:
BamHI/BclI/BglII/BstYI/DpnII
NcoI/BspHI/FatI/PciI
NdeI/AseI/BfaI/Csp6I/MseI
XbaI/AvrII/NheI/SpeI/StyI
XhoI/PspXI/SalI
References
See also
Enzymes
Restriction enzymes | Isocaudomer | [
"Biology"
] | 402 | [
"Genetics techniques",
"Restriction enzymes"
] |
7,172,991 | https://en.wikipedia.org/wiki/Topological%20censorship | The topological censorship theorem (if valid) states that general relativity does not allow an observer to probe the topology of spacetime: any topological structure collapses too quickly to allow light to traverse it. More precisely, in a globally hyperbolic, asymptotically flat spacetime satisfying the null energy condition, every causal curve from past null infinity to future null infinity is fixed-endpoint homotopic to a curve in a topologically trivial neighbourhood of infinity.
A 2013 paper by Sergey Krasnikov claims that the topological censorship theorem was not proven in the original article because of a gap in the proof.
References
Lorentzian manifolds | Topological censorship | [
"Physics"
] | 129 | [
"Relativity stubs",
"Theory of relativity"
] |
7,173,741 | https://en.wikipedia.org/wiki/Ronaldo%20Rog%C3%A9rio%20de%20Freitas%20Mour%C3%A3o | Ronaldo Rogério de Freitas Mourão (25 May 1935 – 25 July 2014) was a Brazilian astronomer and the founder of the Museum of Astronomy and Related Sciences (Museu de Astronomia e Ciências Afins) (MAST), as well as a researcher and titular partner at the Brazilian History and Geography Institute (Instituto Histórico e Geográfico Brasileiro) (IGHB). He was born and died in Rio de Janeiro.
References
External links
Official site
MAST
1935 births
2014 deaths
Brazilian astronomers
20th-century astronomers
Democratic Labour Party (Brazil) politicians
Brazilian Democratic Movement politicians
Christian Democracy (Brazil) politicians | Ronaldo Rogério de Freitas Mourão | [
"Astronomy"
] | 131 | [
"Astronomers",
"Astronomer stubs",
"Astronomy stubs"
] |
7,173,858 | https://en.wikipedia.org/wiki/Orphaned%20technology | Orphaned technology refers to computer technologies that have been abandoned by their original developers. As opposed to deprecation, which tends to be a gradual shift away from an older technology to newer technology, orphaned technology is usually abandoned immediately or with no direct replacement. Unlike abandonware, orphaned technology refers to both software and hardware and the practices around them.
Users of orphaned technologies must often make a choice continuing to use the technology, which may become harder to maintain over time, or switch to other supported technologies, possibly losing capabilities unique to the orphaned technology.
Reasoning
While technology can be abandoned due to an unfavourable design or poor implementation, abandoning a technology can happen for a variety of reasons. There are instances where products are phased out of the market because they are no longer viable as business ventures, such as certain medical technologies.
Some orphaned technologies do not suffer complete abandonment or obsolescence. For instance, there is the case of IBM's Silicon Germanium (SiGe) technology, which is a program that produced an in situ doped alloy as a replacement for the conventional implantation step in silicon semiconductor bipolar process. The technology was previously orphaned but was continued again by a small team at IBM so that it emerged as a leading product in the high-volume communications marketplace.
Technologies orphaned due to failure on the part of their startup developers can be picked up by another investor. One example is Wink, an IoT technology orphaned when its parent company Quirky filed for bankruptcy. The platform, however, continued after it was purchased by another company, Flex.
Examples
Some examples of orphaned technology include:
Apple Lisa - 16/32-bit graphical computer
Apple Newton PDA (Apple Newton) - tablet computer
Apple Classic Mac OS - m68k and PowerPC operating system
Coleco ADAM - 8-bit home computer
DEC Alpha - 64-bit microprocessor
Finale (scorewriter) music notation software developed by MakeMusic from 1988 until 2024
HyperCard - hypermedia
ICAD (KBE) - knowledge-based engineering
Javelin Software - modeling and data analysis
LISP machines - LISP oriented computers
Mattel Aquarius
Microsoft Bob - graphical helper
Mosaic notation program - music notation application by Mark of the Unicorn
Open Music System - Gibson
OpenDoc - compound documents (Mac OS, OS/2)
Poly-1 - parallel networked computer designed in New Zealand for use in education and training
Prograph - visual programming system
TI 99/4A - 16-bit home computer
Windows 9x - x86 operating system
Symbolics Inc's operating systems, Genera and OpenGenera, were twice orphaned, as they were ported from LISP machines to computers using the Alpha 64-bit CPU.
User groups
User groups often exist for specific orphaned technologies, such as The Hong Kong Newton User Group, Symbolics Lisp [Machines] Users' Group (now known as the Association of Lisp Users), and Newton Reference. The Save Sibelius group sprang into existence because Sibelius (scorewriter) users feared the application would be orphaned after its owners Avid Tech fired most of the development team, who were thereafter hired by Steinberg to develop the competing product, Dorico.
See also
Orphan works
Abandonware
Planned obsolescence
References
Orphan works
Technological change
Information technology | Orphaned technology | [
"Technology"
] | 658 | [
"Information and communications technology",
"Information technology"
] |
7,173,874 | https://en.wikipedia.org/wiki/Ecophysiology | Ecophysiology (from Greek , oikos, "house(hold)"; , physis, "nature, origin"; and , -logia), environmental physiology or physiological ecology is a biological discipline that studies the response of an organism's physiology to environmental conditions. It is closely related to comparative physiology and evolutionary physiology. Ernst Haeckel's coinage bionomy is sometimes employed as a synonym.
Plants
Plant ecophysiology is concerned largely with two topics: mechanisms (how plants sense and respond to environmental change) and scaling or integration (how the responses to highly variable conditions—for example, gradients from full sunlight to 95% shade within tree canopies—are coordinated with one another), and how their collective effect on plant growth and gas exchange can be understood on this basis.
In many cases, animals are able to escape unfavourable and changing environmental factors such as heat, cold, drought or floods, while plants are unable to move away and therefore must endure the adverse conditions or perish (animals go places, plants grow places). Plants are therefore phenotypically plastic and have an impressive array of genes that aid in acclimating to changing conditions. It is hypothesized that this large number of genes can be partly explained by plant species' need to live in a wider range of conditions.
Light
Light is the food of plants, i.e. the form of energy that plants use to build themselves and reproduce. The organs harvesting light in plants are leaves and the process through which light is converted into biomass is photosynthesis. The response of photosynthesis to light is called light response curve of net photosynthesis (PI curve). The shape is typically described by a non-rectangular hyperbola. Three quantities of the light response curve are particularly useful in characterising a plant's response to light intensities. The inclined asymptote has a positive slope representing the efficiency of light use, and is called quantum efficiency; the x-intercept is the light intensity at which biochemical assimilation (gross assimilation) balances leaf respiration so that the net CO2 exchange of the leaf is zero, called light compensation point; and a horizontal asymptote representing the maximum assimilation rate. Sometimes after reaching the maximum assimilation declines for processes collectively known as photoinhibition.
As with most abiotic factors, light intensity (irradiance) can be both suboptimal and excessive. Suboptimal light (shade) typically occurs at the base of a plant canopy or in an understory environment. Shade tolerant plants have a range of adaptations to help them survive the altered quantity and quality of light typical of shade environments.
Excess light occurs at the top of canopies and on open ground when cloud cover is low and the sun's zenith angle is low, typically this occurs in the tropics and at high altitudes. Excess light incident on a leaf can result in photoinhibition and photodestruction. Plants adapted to high light environments have a range of adaptations to avoid or dissipate the excess light energy, as well as mechanisms that reduce the amount of injury caused.
Light intensity is also an important component in determining the temperature of plant organs (energy budget).
Temperature
In response to extremes of temperature, plants can produce various proteins. These protect them from the damaging effects of ice formation and falling rates of enzyme catalysis at low temperatures, and from enzyme denaturation and increased photorespiration at high temperatures. As temperatures fall, production of antifreeze proteins and dehydrins increases. As temperatures rise, production of heat shock proteins increases. Metabolic imbalances associated with temperature extremes result in the build-up of reactive oxygen species, which can be countered by antioxidant systems. Cell membranes are also affected by changes in temperature and can cause the membrane to lose its fluid properties and become a gel in cold conditions or to become leaky in hot conditions. This can affect the movement of compounds across the membrane. To prevent these changes, plants can change the composition of their membranes. In cold conditions, more unsaturated fatty acids are placed in the membrane and in hot conditions, more saturated fatty acids are inserted.
Plants can avoid overheating by minimising the amount of sunlight absorbed and by enhancing the cooling effects of wind and transpiration. Plants can reduce light absorption using reflective leaf hairs, scales, and waxes. These features are so common in warm dry regions that these habitats can be seen to form a 'silvery landscape' as the light scatters off the canopies. Some species, such as Macroptilium purpureum, can move their leaves throughout the day so that they are always orientated to avoid the sun (paraheliotropism). Knowledge of these mechanisms has been key to breeding for heat stress tolerance in agricultural plants.
Plants can avoid the full impact of low temperatures by altering their microclimate. For example, Raoulia plants found in the uplands of New Zealand are said to resemble 'vegetable sheep' as they form tight cushion-like clumps to insulate the most vulnerable plant parts and shield them from cooling winds. The same principle has been applied in agriculture by using plastic mulch to insulate the growing points of crops in cool climates in order to boost plant growth.
Water
Too much or too little water can damage plants. If there is too little water then tissues will dehydrate and the plant may die. If the soil becomes waterlogged then the soil will become anoxic (low in oxygen), which can kill the roots of the plant.
The ability of plants to access water depends on the structure of their roots and on the water potential of the root cells. When soil water content is low, plants can alter their water potential to maintain a flow of water into the roots and up to the leaves (Soil plant atmosphere continuum). This remarkable mechanism allows plants to lift water as high as 120 m by harnessing the gradient created by transpiration from the leaves.
In very dry soil, plants close their stomata to reduce transpiration and prevent water loss. The closing of the stomata is often mediated by chemical signals from the root (i.e., abscisic acid). In irrigated fields, the fact that plants close their stomata in response to drying of the roots can be exploited to 'trick' plants into using less water without reducing yields (see partial rootzone drying). The use of this technique was largely developed by Dr Peter Dry and colleagues in Australia
If drought continues, the plant tissues will dehydrate, resulting in a loss of turgor pressure that is visible as wilting. As well as closing their stomata, most plants can also respond to drought by altering their water potential (osmotic adjustment) and increasing root growth. Plants that are adapted to dry environments (Xerophytes) have a range of more specialized mechanisms to maintain water and/or protect tissues when desiccation occurs.
Waterlogging reduces the supply of oxygen to the roots and can kill a plant within days. Plants cannot avoid waterlogging, but many species overcome the lack of oxygen in the soil by transporting oxygen to the root from tissues that are not submerged. Species that are tolerant of waterlogging develop specialised roots near the soil surface and aerenchyma to allow the diffusion of oxygen from the shoot to the root. Roots that are not killed outright may also switch to less oxygen-hungry forms of cellular respiration. Species that are frequently submerged have evolved more elaborate mechanisms that maintain root oxygen levels, such as the aerial roots seen in mangrove forests.
However, for many terminally overwatered houseplants, the initial symptoms of waterlogging can resemble those due to drought. This is particularly true for flood-sensitive plants that show drooping of their leaves due to epinasty (rather than wilting).
concentration
is vital for plant growth, as it is the substrate for photosynthesis. Plants take in through stomatal pores on their leaves. At the same time as enters the stomata, moisture escapes. This trade-off between gain and water loss is central to plant productivity. The trade-off is all the more critical as Rubisco, the enzyme used to capture , is efficient only when there is a high concentration of in the leaf. Some plants overcome this difficulty by concentrating within their leaves using carbon fixation or Crassulacean acid metabolism. However, most species used carbon fixation and must open their stomata to take in whenever photosynthesis is taking place.
The concentration of in the atmosphere is rising due to deforestation and the combustion of fossil fuels. This would be expected to increase the efficiency of photosynthesis and possibly increase the overall rate of plant growth. This possibility has attracted considerable interest in recent years, as an increased rate of plant growth could absorb some of the excess and reduce the rate of global warming. Extensive experiments growing plants under elevated using Free-Air Concentration Enrichment have shown that photosynthetic efficiency does indeed increase. Plant growth rates also increase, by an average of 17% for above-ground tissue and 30% for below-ground tissue. However, detrimental impacts of global warming, such as increased instances of heat and drought stress, mean that the overall effect is likely to be a reduction in plant productivity. Reduced plant productivity would be expected to accelerate the rate of global warming. Overall, these observations point to the importance of avoiding further increases in atmospheric rather than risking runaway climate change.
Wind
Wind has three very different effects on plants.
It affects the exchanges of mass (water evaporation, ) and of energy (heat) between the plant and the atmosphere by renewing the air at the contact with the leaves (convection).
It is sensed as a signal driving a wind-acclimation syndrome by the plant known as thigmomorphogenesis, leading to modified growth and development and eventually to wind hardening.
Its drag force can damage the plant (leaf abrasion, wind ruptures in branches and stems and windthrows and toppling in trees and lodging in crops).
Exchange of mass and energy
Wind influences the way leaves regulate moisture, heat, and carbon dioxide. When no wind is present, a layer of still air builds up around each leaf. This is known as the boundary layer and in effect insulates the leaf from the environment, providing an atmosphere rich in moisture and less prone to convective heating or cooling. As wind speed increases, the leaf environment becomes more closely linked to the surrounding environment. It may become difficult for the plant to retain moisture as it is exposed to dry air. On the other hand, a moderately high wind allows the plant to cool its leaves more easily when exposed to full sunlight. Plants are not entirely passive in their interaction with wind. Plants can make their leaves less vulnerable to changes in wind speed, by coating their leaves in fine hairs (trichomes) to break up the airflow and increase the boundary layer. In fact, leaf and canopy dimensions are often finely controlled to manipulate the boundary layer depending on the prevailing environmental conditions.
Acclimation
Plants can sense the wind through the deformation of its tissues. This signal leads to inhibits the elongation and stimulates the radial expansion of their shoots, while increasing the development of their root system. This syndrome of responses known as thigmomorphogenesis results in shorter, stockier plants with strengthened stems, as well as to an improved anchorage. It was once believed that this occurs mostly in very windy areas. But it has been found that it happens even in areas with moderate winds, so that wind-induced signal were found to be a major ecological factor.
Trees have a particularly well-developed capacity to reinforce their trunks when exposed to wind. From the practical side, this realisation prompted arboriculturalists in the UK in the 1960s to move away from the practice of staking young amenity trees to offer artificial support.
Wind damage
Wind can damage most of the organs of the plants. Leaf abrasion (due to the rubbing of leaves and branches or to the effect of airborne particles such as sand) and leaf of branch breakage are rather common phenomena, that plants have to accommodate. In the more extreme cases, plants can be mortally damaged or uprooted by wind. This has been a major selective pressure acting over terrestrial plants. Nowadays, it is one of the major threatening for agriculture and forestry even in temperate zones. It is worse for agriculture in hurricane-prone regions, such as the banana-growing Windward Islands in the Caribbean.
When this type of disturbance occurs in natural systems, the only solution is to ensure that there is an adequate stock of seeds or seedlings to quickly take the place of the mature plants that have been lost- although, in many cases, a successional stage will be needed before the ecosystem can be restored to its former state.
Animals
Humans
The environment can have major influences on human physiology. Environmental effects on human physiology are numerous; one of the most carefully studied effects is the alterations in thermoregulation in the body due to outside stresses. This is necessary because in order for enzymes to function, blood to flow, and for various body organs to operate, temperature must remain at consistent, balanced levels.
Thermoregulation
To achieve this, the body alters three main things to achieve a constant, normal body temperature:
Heat transfer to the epidermis
The rate of evaporation
The rate of heat production
The hypothalamus plays an important role in thermoregulation. It connects to thermal receptors in the dermis, and detects changes in surrounding blood to make decisions of whether to stimulate internal heat production or to stimulate evaporation.
There are two main types of stresses that can be experienced due to extreme environmental temperatures: heat stress and cold stress.
Heat stress is physiologically combated in four ways: radiation, conduction, convection, and evaporation. Cold stress is physiologically combated by shivering, accumulation of body fat, circulatory adaptations (that provide an efficient transfer of heat to the epidermis), and increased blood flow to the extremities.
There is one part of the body fully equipped to deal with cold stress. The respiratory system protects itself against damage by warming the incoming air to 80-90 degrees Fahrenheit before it reaches the bronchi. This means that not even the most frigid of temperatures can damage the respiratory tract.
In both types of temperature-related stress, it is important to remain well-hydrated. Hydration reduces cardiovascular strain, enhances the ability of energy processes to occur, and reduces feelings of exhaustion.
Altitude
Extreme temperatures are not the only obstacles that humans face. High altitudes also pose serious physiological challenges on the body. Some of these effects are reduced arterial , the rebalancing of the acid-base content in body fluids, increased hemoglobin, increased RBC synthesis, enhanced circulation, and increased levels of the glycolysis byproduct 2,3 diphosphoglycerate, which promotes off-loading of O2 by hemoglobin in the hypoxic tissues.
Environmental factors can play a huge role in the human body's fight for homeostasis. However, humans have found ways to adapt, both physiologically and tangibly.
Scientists
George A. Bartholomew (1919–2006) was a founder of animal physiological ecology. He served on the faculty at UCLA from 1947 to 1989, and almost 1,200 individuals can trace their academic lineages to him. Knut Schmidt-Nielsen (1915–2007) was also an important contributor to this specific scientific field as well as comparative physiology.
Hermann Rahn (1912–1990) was an early leader in the field of environmental physiology. Starting out in the field of zoology with a Ph.D. from University of Rochester (1933), Rahn began teaching physiology at the University of Rochester in 1941. It is there that he partnered with Wallace O. Fenn to publish A Graphical Analysis of the Respiratory Gas Exchange in 1955. This paper included the landmark O2-CO2 diagram, which formed the basis for much of Rahn's future work. Rahn's research into applications of this diagram led to the development of aerospace medicine and advancements in hyperbaric breathing and high-altitude respiration. Rahn later joined the University at Buffalo in 1956 as the Lawrence D. Bell Professor and Chairman of the Department of Physiology. As Chairman, Rahn surrounded himself with outstanding faculty and made the University an international research center in environmental physiology.
See also
Comparative physiology
Evolutionary physiology
Ecology
Phylogenetic comparative methods
Plant physiology
Raymond B. Huey
Theodore Garland, Jr.
Tyrone Hayes
References
Further reading
Spicer, J. I., and K. J. Gaston. 1999. Physiological diversity and its ecological implications. Blackwell Science, Oxford, U.K. x + 241 pp.
. Definitions and Opinions by: G. A. Bartholomew, A. F. Bennett, W. D. Billings, B. F. Chabot, D. M. Gates, B. Heinrich, R. B. Huey, D. H. Janzen, J. R. King, P. A. McClure, B. K. McNab, P. C. Miller, P. S. Nobel, B. R. Strain.
Subfields of ecology
Physiology
Animal physiology
Plant physiology
Ecology terminology
Animal ecology
Plant ecology
Articles containing video clips | Ecophysiology | [
"Biology"
] | 3,590 | [
"Plant physiology",
"Ecology terminology",
"Animals",
"Animal physiology",
"Plants",
"Physiology",
"Plant ecology"
] |
7,174,276 | https://en.wikipedia.org/wiki/Half%20sphere%20exposure | Half Sphere exposure (HSE) is a protein solvent exposure measure that was first introduced by .
Like all solvent exposure measures it measures how buried amino acid residues are in a protein. It is found by counting the number of amino acid neighbors within two half spheres of chosen radius around the amino acid. The calculation of HSE is found by dividing a contact number (CN) sphere in two halves by the plane perpendicular to the
Cβ-Cα vector. This simple division of the CN sphere results in
two strikingly different measures, HSE-up and HSE-down. HSE-up is defined as the number of Cα atoms in the
upper half (containing the pseudo-Cβ atom) and analogously HSE-down is defined as the number of Cα atoms
in the opposite sphere.
If only Cα atoms are available (as is the case for many simplified representations of protein structure), a related measure, called HSEα, can be used. HSEα uses a pseudo-Cβ instead of the real Cβ atom for its
calculation. The position of this pseudo-Cβ atom (pCβ) is derived from the positions of preceding
Cα−1 and the following Cα+1. The Cα-pCβ vector is calculated by adding the
Cα−1-Cα0 and Cα+1-Cα0 vectors.
HSE is used in predicting discontinuous B-cell epitopes. Song et al. have developed an online webserver termed HSEpred to predict half-sphere exposure from protein primary sequences. HSEpred server can achieve the correlation coefficients of 0.72 and 0.68 between the predicted and observed HSE-up and HSE-down measures, respectively, when evaluated on a well-prepared non-homologous protein structure dataset. Moreover, residue contact number (CN) can also be accurately predicted by HSEpred webserver using the summation of the predicted HSE-up and HSE-down values, which has further enlarged the application of this new solvent exposure measure.
Recently, Heffernan et al. has developed the most accurate predictor for both HSEα and HSEβ based on a big dataset by using multiple-step iterative deep neural-network learning. The predicted HSEa shows a higher correlation coefficient to the stability change by residue mutants than predicted HSEβ and ASA. The results, together with its easy Ca-atom-based calculation, highlight the potential usefulness of
predicted HSEa for protein structure prediction and refinement as well as function prediction.
References
Amino acids
Protein structure
Nitrogen cycle | Half sphere exposure | [
"Chemistry"
] | 537 | [
"Biomolecules by chemical classification",
"Amino acids",
"Nitrogen cycle",
"Structural biology",
"Protein structure",
"Metabolism"
] |
7,174,467 | https://en.wikipedia.org/wiki/Connected-component%20labeling | Connected-component labeling (CCL), connected-component analysis (CCA), blob extraction, region labeling, blob discovery, or region extraction is an algorithmic application of graph theory, where subsets of connected components are uniquely labeled based on a given heuristic. Connected-component labeling is not to be confused with segmentation.
Connected-component labeling is used in computer vision to detect connected regions in binary digital images, although color images and data with higher dimensionality can also be processed. When integrated into an image recognition system or human-computer interaction interface, connected component labeling can operate on a variety of information. Blob extraction is generally performed on the resulting binary image from a thresholding step, but it can be applicable to gray-scale and color images as well. Blobs may be counted, filtered, and tracked.
Blob extraction is related to but distinct from blob detection.
Overview
A graph, containing vertices and connecting edges, is constructed from relevant input data. The vertices contain information required by the comparison heuristic, while the edges indicate connected 'neighbors'. An algorithm traverses the graph, labeling the vertices based on the connectivity and relative values of their neighbors. Connectivity is determined by the medium; image graphs, for example, can be 4-connected neighborhood or 8-connected neighborhood.
Following the labeling stage, the graph may be partitioned into subsets, after which the original information can be recovered and processed .
Definition
The usage of the term connected-components labeling (CCL) and its definition is quite consistent in the academic literature, whereas connected-components analysis (CCA) varies in terms of both terminology and problem definition.
Rosenfeld et al. define connected components labeling as the “[c]reation of a labeled image in which the positions associated with the same connected component of the binary input image have a unique label.” Shapiro et al. define CCL as an operator whose “input is a binary image and [...] output is a symbolic image in which the label assigned to each pixel is an integer uniquely identifying the connected component to which that pixel belongs.”
There is no consensus on the definition of CCA in the academic literature. It is often used interchangeably with CCL. A more extensive definition is given by Shapiro et al.: “Connected component analysis consists of connected component labeling of the black pixels followed by property measurement of the component regions and decision making.” The definition for connected-component analysis presented here is more general, taking the thoughts expressed in into account.
Algorithms
The algorithms discussed can be generalized to arbitrary dimensions, albeit with increased time and space complexity.
One component at a time
This is a fast and very simple method to implement and understand. It is based on graph traversal methods in graph theory. In short, once the first pixel of a connected component is found, all the connected pixels of that connected component are labelled before going onto the next pixel in the image. This algorithm is part of Vincent and Soille's watershed segmentation algorithm, other implementations also exist.
In order to do that a linked list is formed that will keep the indexes of the pixels that are connected to each other, steps (2) and (3) below. The method of defining the linked list specifies the use of a depth or a breadth first search. For this particular application, there is no difference which strategy to use. The simplest kind of a last in first out queue implemented as a singly linked list will result in a depth first search strategy.
It is assumed that the input image is a binary image, with pixels being either background or foreground and that the connected components in the foreground pixels are desired. The algorithm steps can be written as:
Start from the first pixel in the image. Set current label to 1. Go to (2).
If this pixel is a foreground pixel and it is not already labelled, give it the current label and add it as the first element in a queue, then go to (3). If it is a background pixel or it was already labelled, then repeat (2) for the next pixel in the image.
Pop out an element from the queue, and look at its neighbours (based on any type of connectivity). If a neighbour is a foreground pixel and is not already labelled, give it the current label and add it to the queue. Repeat (3) until there are no more elements in the queue.
Go to (2) for the next pixel in the image and increment current label by 1.
Note that the pixels are labelled before being put into the queue. The queue will only keep a pixel to check its neighbours and add them to the queue if necessary. This algorithm only needs to check the neighbours of each foreground pixel once and doesn't check the neighbours of background pixels.
The pseudocode is :
algorithm OneComponentAtATime(data)
input : imageData[xDim][yDim]
initialization : label = 0, labelArray[xDim][yDim] = 0, statusArray[xDim][yDim] = false, queue1, queue2;
for i = 0 to xDim do
for j = 0 to yDim do
if imageData[i][j] has not been processed do
if imageData[i][j] is a foreground pixel do
check it four neighbors(north, south, east, west) :
if neighbor is not processed do
if neighbor is a foreground pixel do
add it to the queue1
else
update its status as processed
end if
labelArray[i][j] = label (give label)
statusArray[i][j] = true (update status)
while queue1 is not empty do
For each pixel in the queue do :
check it fours neighbors
if neighbor is not processed do
if neighbor is a foreground pixel do
add it to the queue2
else
update its status as processed
end if
give it the current label
update its status as processed
remove the current element from queue1
copy queue2 into queue1
end While
increase the label
end if
else
update its status as processed
end if
end if
end if
end for
end for
Two-pass
Relatively simple to implement and understand, the two-pass algorithm, (also known as the Hoshen–Kopelman algorithm) iterates through 2-dimensional binary data. The algorithm makes two passes over the image: the first pass to assign temporary labels and record equivalences, and the second pass to replace each temporary label by the smallest label of its equivalence class.
The input data can be modified in situ (which carries the risk of data corruption), or labeling information can be maintained in an additional data structure.
Connectivity checks are carried out by checking neighbor pixels' labels (neighbor elements whose labels are not assigned yet are ignored), or say, the north-east, the north, the north-west and the west of the current pixel (assuming 8-connectivity). 4-connectivity uses only north and west neighbors of the current pixel. The following conditions are checked to determine the value of the label to be assigned to the current pixel (4-connectivity is assumed)
Conditions to check:
Does the pixel to the left (west) have the same value as the current pixel?
Yes – We are in the same region. Assign the same label to the current pixel
No – Check next condition
Do both pixels to the north and west of the current pixel have the same value as the current pixel but not the same label?
Yes – We know that the north and west pixels belong to the same region and must be merged. Assign the current pixel the minimum of the north and west labels, and record their equivalence relationship
No – Check next condition
Does the pixel to the left (west) have a different value and the one to the north the same value as the current pixel?
Yes – Assign the label of the north pixel to the current pixel
No – Check next condition
Do the pixel's north and west neighbors have different pixel values than current pixel?
Yes – Create a new label id and assign it to the current pixel
The algorithm continues this way, and creates new region labels whenever necessary. The key to a fast algorithm, however, is how this merging is done. This algorithm uses the union-find data structure which provides excellent performance for keeping track of equivalence relationships. Union-find essentially stores labels which correspond to the same blob in a disjoint-set data structure, making it easy to remember the equivalence of two labels by the use of an interface method E.g.: findSet(l). findSet(l) returns the minimum label value that is equivalent to the function argument 'l'.
Once the initial labeling and equivalence recording is completed, the second pass merely replaces each pixel label with its equivalent disjoint-set representative element.
A faster-scanning algorithm for connected-region extraction is presented below.
On the first pass:
Iterate through each element of the data by column, then by row (Raster Scanning)
If the element is not the background
Get the neighboring elements of the current element
If there are no neighbors, uniquely label the current element and continue
Otherwise, find the neighbor with the smallest label and assign it to the current element
Store the equivalence between neighboring labels
On the second pass:
Iterate through each element of the data by column, then by row
If the element is not the background
Relabel the element with the lowest equivalent label
Here, the background is a classification, specific to the data, used to distinguish salient elements from the foreground. If the background variable is omitted, then the two-pass algorithm will treat the background as another region.
Graphical example of two-pass algorithm
1. The array from which connected regions are to be extracted is given below (8-connectivity based).
We first assign different binary values to elements in the graph. The values "0~1" at the center of each of the elements in the following graph are the elements' values, whereas the "1,2,...,7" values in the next two graphs are the elements' labels. The two concepts should not be confused.
2. After the first pass, the following labels are generated:
A total of 7 labels are generated in accordance with the conditions highlighted above.
The label equivalence relationships generated are,
3. Array generated after the merging of labels is carried out. Here, the label value that was the smallest for a given region "floods" throughout the connected region and gives two distinct labels, and hence two distinct labels.
4. Final result in color to clearly see two different regions that have been found in the array.
The pseudocode is:
algorithm TwoPass(data) is
linked = []
labels = structure with dimensions of data, initialized with the value of Background
NextLabel = 0
First pass
for row in data do
for column in row do
if data[row][column] is not Background then
neighbors = connected elements with the current element's value
if neighbors is empty then
linked[NextLabel] = set containing NextLabel
labels[row][column] = NextLabel
NextLabel += 1
else
Find the smallest label
L = neighbors labels
labels[row][column] = min(L)
for label in L do
linked[label] = union(linked[label], L)
Second pass
for row in data do
for column in row do
if data[row][column] is not Background then
labels[row][column] = find(labels[row][column])
return labels
The find and union algorithms are implemented as described in union find.
Sequential algorithm
Create a region counter
Scan the image (in the following example, it is assumed that scanning is done from left to right and from top to bottom):
For every pixel check the north and west pixel (when considering 4-connectivity) or the northeast, north, northwest, and west pixel for 8-connectivity for a given region criterion (i.e. intensity value of 1 in binary image, or similar intensity to connected pixels in gray-scale image).
If none of the neighbors fit the criterion then assign to region value of the region counter. Increment region counter.
If only one neighbor fits the criterion assign pixel to that region.
If multiple neighbors match and are all members of the same region, assign pixel to their region.
If multiple neighbors match and are members of different regions, assign pixel to one of the regions (it doesn't matter which one). Indicate that all of these regions are equivalent.
Scan image again, assigning all equivalent regions the same region value.
Others
Some of the steps present in the two-pass algorithm can be merged for efficiency, allowing for a single sweep through the image. Multi-pass algorithms also exist, some of which run in linear time relative to the number of image pixels.
In the early 1990s, there was considerable interest in parallelizing connected-component algorithms in image analysis applications, due to the bottleneck of sequentially processing each pixel.
The interest to the algorithm arises again with an extensive use of CUDA.
Pseudocode for the one-component-at-a-time algorithm
Algorithm:
Connected-component matrix is initialized to size of image matrix.
A mark is initialized and incremented for every detected object in the image.
A counter is initialized to count the number of objects.
A row-major scan is started for the entire image.
If an object pixel is detected, then following steps are repeated while (Index !=0)
Set the corresponding pixel to 0 in Image.
A vector (Index) is updated with all the neighboring pixels of the currently set pixels.
Unique pixels are retained and repeated pixels are removed.
Set the pixels indicated by Index to mark in the connected-component matrix.
Increment the marker for another object in the image.
One-Component-at-a-Time(image)
[M, N] := size(image)
connected := zeros(M, N)
mark := value
difference := increment
offsets := [-1; M; 1; -M]
index := []
no_of_objects := 0
for i: 1:M do
for j: 1:N do
if (image(i, j) == 1) then
no_of_objects := no_of_objects + 1
index := [((j-1) × M + i)]
connected(index) := mark
while ~isempty(index) do
image(index) := 0
neighbors := bsxfun(@plus, index, offsets)
neighbors := unique(neighbors(:))
index := neighbors(find(image(neighbors)))
connected(index) := mark
end while
mark := mark + difference
end if
end for
end for
The run time of the algorithm depends on the size of the image and the amount of foreground. The time complexity is comparable to the two pass algorithm if the foreground covers a significant part of the image. Otherwise the time complexity is lower. However, memory access is less structured than for the two-pass algorithm, which tends to increase the run time in practice.
Performance evaluation
In the last two decades many novel approaches to connected-component labeling have been proposed, but almost none of them have been subjected to a comparative performance assessment using the same data set. YACCLAB
(acronym for Yet Another Connected Components Labeling Benchmark) is an example of C++ open source framework which collects, runs, and tests connected-component labeling algorithms.
Hardware architectures
The emergence of FPGAs with enough capacity to perform complex image processing tasks also led to high-performance architectures for connected-component labeling. Most of these architectures utilize the single pass variant of this algorithm, because of the limited memory resources available on an FPGA. These types of connected component labeling architectures can process several image pixels in parallel, thereby achieving high throughput and low processing latency.
See also
Feature extraction
Flood fill
References
General
External links
Implementation in C#
about Extracting objects from image and Direct Connected Component Labeling Algorithm
Computer vision | Connected-component labeling | [
"Engineering"
] | 3,311 | [
"Artificial intelligence engineering",
"Packaging machinery",
"Computer vision"
] |
7,174,639 | https://en.wikipedia.org/wiki/Insertion%20time | In nuclear weaponry, insertion time is the interval required to rearrange a subcritical mass of fissile material into critical mass.
Appropriate insertion time is one of the three main requirements to create a working fission atomic bomb. The need for a short insertion time with plutonium-239 is the reason the implosion method was chosen for the first plutonium bomb, while with uranium-235 it is possible to use a gun design.
The basic requirements are:
Start with a subcritical system
Create a super prompt critical system
Switch between these two states in a length of time (insertion time) shorter than the time between the random appearance of a neutron in the fissile material through spontaneous fission or by other random processes.
At the right moment, neutrons must be injected into the fissile material to start the fission process. This can be done by several methods.
Alpha emitters such as polonium or plutonium-238 can be rapidly combined with beryllium to create a neutron source.
Neutrons can be generated using an electrostatic discharge tube, this tube uses the D-T reaction.
References
Nuclear weapons
Nuclear physics
Nuclear technology | Insertion time | [
"Physics"
] | 233 | [
"Nuclear technology",
"Nuclear physics"
] |
7,175,685 | https://en.wikipedia.org/wiki/Westerlund%201 | Westerlund 1 (abbreviated Wd1, sometimes called Ara Cluster) is a compact young super star cluster about 3.8 kpc (12,000 ly) away from Earth. It is thought to be the most massive young star cluster in the Milky Way, and was discovered by Bengt Westerlund in 1961 but remained largely unstudied for many years due to high interstellar absorption in its direction. In the future, it will probably evolve into a globular cluster.
The cluster contains a large number of rare, evolved, high-mass stars, including: 6 yellow hypergiants, 4 red supergiants including Westerlund 1-26, one of the largest known stars, 24 Wolf-Rayet stars, a luminous blue variable, many OB supergiants, and an unusual supergiant sgB[e] star which has been proposed to be the remnant of a recent stellar merger. In addition, X-ray observations have revealed the presence of the anomalous X-ray pulsar CXO J164710.20-455217, a slow rotating neutron star that must have formed from a high-mass progenitor star. Westerlund 1 is believed to have formed in a single burst of star formation, implying the constituent stars have similar ages and compositions.
Aside from hosting some of the most massive and least-understood stars in our galaxy, Westerlund 1 is useful as a relatively nearby, easy to observe super star cluster that can help astronomers determine what occurs within extragalactic super star clusters.
Observations
The brightest O7–8V main sequence stars in Wd1 have V-band photometric magnitudes around 20.5, and therefore at visual wavelengths Wd1 is dominated by highly luminous post-Main Sequence stars (V-band magnitudes of 14.5–18, absolute magnitudes −7 to −10), along with less-luminous post-Main Sequence stars of luminosity class Ib and II (V-band magnitudes of 18–20). Due to the extremely high interstellar reddening towards Wd1, it is very difficult to observe in the U- and B-bands, and most observations are made in the R- or I-bands at the red end of the spectrum or in the infrared. Stars in the cluster are generally named using a classification introduced by Westerlund, although a separate naming convention is often used for the Wolf-Rayet stars.
At X-ray wavelengths, Wd1 shows diffuse emission from interstellar gas and point emission from both high-mass, post-Main Sequence and low mass, pre-Main Sequence stars. The Westerlund 1 magnetar is the most luminous X-ray point source in the cluster, with the sgB[e] star W9, the (presumed) binary W30a and the Wolf–Rayet stars WR A and WR B all strong X-ray sources. Approximately 50 other X-ray point sources are associated with luminous optical counterparts. Finally, at radio wavelengths the sgB[e] star W9 and red supergiants W20 and W26 are strong radio sources, while the majority of the cool hypergiants and a few OB supergiants and Wolf–Rayet stars are also detected.
Age and evolutionary state
The age of Wd1 is estimated at 4–5 Myr from comparison of the population of evolved stars with models of stellar evolution. The presence of significant numbers of both Wolf–Rayet stars and red and yellow supergiants in Wd1 represents a strong constraint on the age: theory suggests that red supergiants will not form until around 4 Myr as the most massive stars do not go through a red supergiant phase, while the Wolf–Rayet population declines sharply after 5 Myr. This range of ages is broadly consistent with infra-red observations of Wd1 that reveal the presence of late-O main sequence stars, although a lower age of around 3.5 Myr has been suggested from observations of lower-mass stars in Wd1.
If Wd1 formed stars with a typical initial mass function then the cluster would have originally contained a significant number of very massive stars, such as those currently observed in the younger Arches cluster. Current estimates of the age of Wd1 are greater than the lifetimes of these stars, and stellar evolution models suggest that there would already have been 50–150 supernovae in Wd1, with a supernova rate of approximately one per 10,000 years over the last million years. However, to date only one definitive supernova remnant has been detected—the Westerlund 1 magnetar—and the lack of other compact objects and high-mass X-ray binaries is puzzling. A number of suggestions have been put forward, including high supernova kick velocities that disrupt binary systems, the formation of slowly accreting (and therefore undetectable) stellar mass black holes, or binary systems in which both objects are now compact objects, but the problem has yet to be resolved.
As the stars in Westerlund 1 have the same age, composition and distance, the cluster represents an ideal environment for understanding the evolution of massive stars. The simultaneous presence of stars evolving on to and off of the Main Sequence presents a robust test for stellar evolution models, which are also currently unable to correctly predict the observed distribution of Wolf–Rayet subtypes in Westerlund 1.
Binary fraction
A number of lines of evidence point to a high binary fraction amongst the high-mass stars in Wd1. Some massive binaries are detected directly
through photometry and radial velocity observations, while many others are inferred through secondary characteristics (such as high X-ray luminosity, non-thermal radio spectra and excess infra-red emission) that are typical of colliding-wind binaries or dust-forming Wolf–Rayet stars. Overall binary fractions of 70% for the Wolf–Rayet population and in excess of 40% for the OB supergiants are currently estimated, although both may be incomplete.
Members
As well as documented members of the cluster, the luminous blue variable MN44 is thought to be a runaway star ejected from Westerlund 1 four to five million years ago.
References
External links
Artist’s impression of a magnetar X-ray satellites catch magnetar in gigantic stellar ‘hiccup’, ESA website, 2007
Image of Westerlund 1
Neutron star found where black hole expected
Open clusters
Super star clusters
Ara (constellation)
277-12
Astronomical objects discovered in 1961 | Westerlund 1 | [
"Astronomy"
] | 1,348 | [
"Constellations",
"Ara (constellation)"
] |
7,175,772 | https://en.wikipedia.org/wiki/Ferroelectret | A ferroelectret, also known as a piezoelectret, is a thin film of polymer foams, exhibiting piezoelectric and pyroelectric properties after electric charging. Ferroelectret foams usually consist of a cellular polymer structure filled with air. Polymer-air composites are elastically soft due to their high air content as well as due to the size and shape of the polymer walls. Their elastically soft composite structure is one essential key for the working principle of ferroelectrets, besides the permanent trapping of electric charges inside the polymer voids. The elastic properties allow large deformations of the electrically charged voids. However, the composite structure can also possibly limit the stability and consequently the range of applications.
How it works
The most common effect related to ferroelectrets is the direct and inverse piezoelectricity, but in these materials, the effect occurs in a way different from the respective effect in ferroelectric polymers. In ferroelectric polymers, a stress in the 3-direction mainly decreases the distance between the molecular chains, due to the relatively weak van der Waals and electrostatic interactions between chains in comparison to the strong covalent bonds within the chain. The thickness decrease thus results in an increase of the dipole density and thus in an increase of the charges on the electrodes, yielding a negative d33 coefficient from dipole-density (or secondary) piezoelectricity. In cellular polymers (ferroelectrets), stress in the 3-direction also decreases the thickness of the sample. The thickness decrease occurs dominantly across the voids, the macroscopic dipole moments decrease, and so do the electrode charges, yielding a positive d33 (intrinsic or direct (quasi-)piezoelectricity).
New features
In recent years, alternatives to the cellular-foam ferroelectrets were developed. In the new polymer systems, the required cavities are formed by means of e.g. stamps, templates, laser cutting, etc. Thermo-forming of layer systems from electret films led to thermally more stable ferroelectrets.
Notes
References
Condensed matter physics
Electrical phenomena | Ferroelectret | [
"Physics",
"Chemistry",
"Materials_science",
"Engineering"
] | 459 | [
"Physical phenomena",
"Phases of matter",
"Materials science",
"Electrical phenomena",
"Condensed matter physics",
"Matter"
] |
7,175,817 | https://en.wikipedia.org/wiki/Emotional%20bias | An emotional bias is a distortion in cognition and decision making due to emotional factors.
For example, a person might be inclined:
to attribute negative judgements to neutral events or objects;
to believe something that has a positive emotional effect, that gives a pleasant feeling, even if there is evidence to the contrary;
to be reluctant to accept hard facts that are unpleasant and give mental suffering.
Effect of dispositional emotionality
Emotional bias is often the effect of dispositional emotionality that an individual has before the occurrence of events that could cause these emotions. These states were linked to the dysregulation in opioid receptor systems and are commonly known as temperament traits The examples are dispositional dysphoria, irritability, withdrawal, or dispositional good and relaxed moods. These dispositions create emotional biases in cognition. Studies of meaning attribution in 24 groups contrasted by various temperament traits showed that people with high neuroticism, high emotionality and weak endurance perceived neutral abstract concepts more negatively than people with low neuroticism and strong endurance.
Other effects
Effects of emotional biases can be similar to those of a cognitive bias, it can even be considered as a subcategory of such biases. The specificity is that the cause lies in one's desires or fears, which divert the attention of the person, more than in one's reasoning.
Neuroscience experiments have shown how emotions and cognition, which are present in different areas of the human brain, interfere with each other in decision making process, resulting often in a primacy of emotions over reasoning
Emotional bias might help explain the tendency towards over-optimism or over-pessimism, even when evidence for a more rational conclusion is available.
Emotional attention bias
Influences
Sleep
Emotional attention bias can be influenced by sleep. Studies have been performed and have shown that sleep deprivation in children reduces their ability to adjust their behavior in emotional situations. Children showed high emotional attention biases when deprived of sleep. This occurs because sleep prepares the body for emotional challenges.
Decision making
Emotions have a small to large impact on the decisions we make depending on the type of emotion. Some of the most influential emotions for decision-making are sadness, disgust, and guilt. Anger differs the most from fear and sadness in both judgment and decision-making contexts. Fear is associated with uncertainty, while sadness is associated with a perception that outcomes are due to the situation. Angry decision-makers tend to make choices quickly and are unlikely to analyze their decisions. Stress can play a role in decision-making. Acute stress can alter the response to moral dilemmas. On the other hand, stress does not always alter everyday, moral decision-making. One study looked at the role emotions play in adolescents' moral decision-making. In a hypothetical, prosocial behavioral context, positively charged self-evaluative emotions most strongly predict moral choice. In anti-social behaviors, negatively charged, critical emotions most strongly predict moral choice. Regret and disappointment are emotions experienced after a decision. In some cases, regret has created a stronger desire to switch choices than disappointment.
Emotions affect different types of decisions. Emotions have a strong influence on economic behavior and decision-making. In some behavioral anomalies, certain emotions related to some tasks can have an increased impact. In one experiment, researchers looked at what emotions manifest the disposition effect, where individuals sell winning shares and hold losing ones. They found that elation for winners and regret for losers are necessary emotions that can cause the effect to occur. In regards to patients making a medical decision, emotions and one's motivational goals, play a part as well. One study looked at the elements of coping behaviors. The first two elements have to do with the need to control the cognitive and emotional elements of the health threat; the second pair of elements relate to the management of cognitive and emotional aspects of the decision itself.
Brain damage can cause changes in normal decision-making processes. The amygdala is an area in the brain involved in emotion. Studies have found that patients with bilateral amygdala damage, which is damage in both hemispheres of the amygdala region in the brain, are deficient in decision-making. When an initial choice is made in decision-making, the result of this choice has an emotional response, which is controlled by the amygdala.
See also
Conformity
Emotional reasoning
Emotions in decision making
Wishful thinking
References
Bias
Decision-making
Emotion | Emotional bias | [
"Biology"
] | 900 | [
"Emotion",
"Behavior",
"Human behavior"
] |
7,175,888 | https://en.wikipedia.org/wiki/IBM%20Balanced%20Configuration%20Unit | The IBM Data Warehousing Balanced Configuration Unit is a family of data warehousing servers from IBM. IBM introduced the Balanced Configuration Unit (BCU) for AIX in 2005, and the BCU for Linux in 2006. The BCU is a "balanced" combination of computer server hardware (cpus, I/O channels, and storage) combined with DB2 Data Warehouse Edition (DB2 DWE) software to form a data warehouse "appliance like" system to compete with systems such as Greenplum, DATAllegro, Netezza Performance Server, and Teradata.
See also IBM Linux Solution Optimizes Enterprise Data Warehousing.
External links
IBM's InfoSphere Balanced Warehouse web page:
Balanced | IBM Balanced Configuration Unit | [
"Technology"
] | 151 | [
"Computing stubs",
"Computer hardware stubs"
] |
7,177,216 | https://en.wikipedia.org/wiki/William%20N.%20Schoenfeld | William N. Schoenfeld (December 6, 1915 – August 3, 1996) was an American psychologist and author.
Born in New York City, he conducted original research in experimental psychology, and advocated behaviorism, which seeks to understand behavior as a function of environmental histories of experiencing consequences. Dr. Schoenfeld's own original contributions in a long research career were influenced by those of B.F. Skinner and Ivan Pavlov. In a carefully devised set of experiments in 1953 he led a team of Columbia University psychologists in discovering that anxiety caused the human heart rate to slow rather than quicken under certain timing of stimuli.
He was the co-author with Fred S. Keller, a Columbia colleague, of Principles of Psychology, an influential college text published in 1950 that emphasized scientific methods in the study of psychology. Students first used it in courses at Columbia College, where the two professors offered two hours of lecture and, for the first time in psychology, four hours of laboratory work a week. Among their experiments, the students observed the responses of white rats to stimuli and rewards and measured human learning by testing people's ability to remember the pathways of mazes and other sensory processes.<ref>Root, Michael J. "Keller, Fred S." In Carnes, Mark C., ed. (2005). [https://books.google.com/books?id=wZczV8ZxgL4C&pg=PA306 American National Biography: Supplement 2], p. 306. Oxford University Press.</ref> Together with Keller, they pioneered the first introductory psychology course to provide a laboratory animal model for behavior, which led to so many more like his (Hearst, E., 1997).
William Nathan Schoenfeld graduated from the College of the City of New York in 1937 and earned an MA in 1939 and a Ph.D. at Columbia in 1942. Although he was a Chemistry major as an undergraduate, he took courses in physics, biology, mathematics, and geology. With the help of the various courses, Schoenfeld was able to build a solid foundation for his approach to analyzing behavior using the scientific method. In 1937, Schoenfeld was the only student to graduate with a psychology degree and receive a Bachelor of Science degree.
Schoenfeld became a lecturer in psychology at Columbia in 1942, an instructor in 1946, associate professor in 1952 and a full professor in 1958. He joined the faculty of Queens College of the City University of New York in 1966, to become the chairman of the psychology department and was named a professor emeritus in 1983. Later he taught in the psychology department of the Hebrew University in Jerusalem and at universities in Mexico, Venezuela and Brazil. He was awarded an honorary degree by the University of Guadalajara in Mexico.
Throughout his career, he wrote or contributed to over 100 publications of learning theory such as: The Theory of Reinforcement Schedules (1970), Stimulus Schedules (1972) and Religion and Human Behavior (1993). Schoenfeld also published an article in 1941 called Psychological Review while he was an undergraduate at Columbia University. After publishing the Psychological Review, Schoenfeld was acknowledged as one of the most distinguished theorists of psychology.
He was president of the division of the analysis of behavior of the American Psychological Association and president of the Eastern Psychological Association (1972–1973) and the Pavlovian Society of North America. He was an editor of the Journal of Comparative and Physiological Psychology and Conditional Reflex''. He was also one of the major contributors to the founding of the Journal of the Experimental Analysis of Behavior.
Students
William N. Schoenfeld was a prolific doctoral advisor, who is said to have ultimately valued his teaching more than his research. Indeed, many of his students continued into prominence in their own right. They include:
P. J. Bersh, A. Charles Catania, W. W. Cumming, James A. Dinsmoor, Charles Ferster, Peter Harzem, Eliot S. Hearst, Francis Mechner, John Anthony Nevin, Ovide F. Pomerleau, Emilio Ribes, Murray Sidman, Carlos Bruner.
References
External links
Columbia University
New York Times obituary
1915 births
1996 deaths
20th-century American psychologists
Behaviourist psychologists
Columbia University faculty
City College of New York alumni
Columbia University alumni
Queens College, City University of New York faculty | William N. Schoenfeld | [
"Biology"
] | 898 | [
"Behaviourist psychologists",
"Behavior",
"Behaviorism"
] |
7,177,687 | https://en.wikipedia.org/wiki/Gross%E2%80%93Pitaevskii%20equation | The Gross–Pitaevskii equation (GPE, named after Eugene P. Gross and Lev Petrovich Pitaevskii) describes the ground state of a quantum system of identical bosons using the Hartree–Fock approximation and the pseudopotential interaction model.
A Bose–Einstein condensate (BEC) is a gas of bosons that are in the same quantum state, and thus can be described by the same wavefunction. A free quantum particle is described by a single-particle Schrödinger equation. Interaction between particles in a real gas is taken into account by a pertinent many-body Schrödinger equation. In the Hartree–Fock approximation, the total wave-function of the system of bosons is taken as a product of single-particle functions :
where is the coordinate of the -th boson. If the average spacing between the particles in a gas is greater than the scattering length (that is, in the so-called dilute limit), then one can approximate the true interaction potential that features in this equation by a pseudopotential. At sufficiently low temperature, where the de Broglie wavelength is much longer than the range of boson–boson interaction, the scattering process can be well approximated by the s-wave scattering (i.e. in the partial-wave analysis, a.k.a. the hard-sphere potential) term alone. In that case, the pseudopotential model Hamiltonian of the system can be written as
where is the mass of the boson, is the external potential, is the boson–boson s-wave scattering length, and is the Dirac delta-function.
The variational method shows that if the single-particle wavefunction satisfies the following Gross–Pitaevskii equation
the total wave-function minimizes the expectation value of the model Hamiltonian under normalization condition Therefore, such single-particle wavefunction describes the ground state of the system.
GPE is a model equation for the ground-state single-particle wavefunction in a Bose–Einstein condensate. It is similar in form to the Ginzburg–Landau equation and is sometimes referred to as the nonlinear Schrödinger equation.
The non-linearity of the Gross–Pitaevskii equation has its origin in the interaction between the particles: setting the coupling constant of interaction in the Gross–Pitaevskii equation to zero (see the following section) recovers the single-particle Schrödinger equation describing a particle inside a trapping potential.
The Gross–Pitaevskii equation is said to be limited to the weakly interacting regime. Nevertheless, it may also fail to reproduce interesting phenomena even within this regime. In order to study the BEC beyond that limit of weak interactions, one needs to implement the Lee-Huang-Yang (LHY) correction. Alternatively, in 1D systems one can use either an exact approach, namely the Lieb-Liniger model, or an extended equation, e.g. the Lieb-Liniger Gross–Pitaevskii equation (sometimes called modified or generalized nonlinear Schrödinger equation).
Form of equation
The equation has the form of the Schrödinger equation with the addition of an interaction term. The coupling constant is proportional to the s-wave scattering length of two interacting bosons:
where is the reduced Planck constant, and is the mass of the boson. The energy density is
where is the wavefunction, or order parameter, and is the external potential (e.g. a harmonic trap). The time-independent Gross–Pitaevskii equation, for a conserved number of particles, is
where is the chemical potential, which is found from the condition that the number of particles is related to the wavefunction by
From the time-independent Gross–Pitaevskii equation, we can find the structure of a Bose–Einstein condensate in various external potentials (e.g. a harmonic trap).
The time-dependent Gross–Pitaevskii equation is
From this equation we can look at the dynamics of the Bose–Einstein condensate. It is used to find the collective modes of a trapped gas.
Solutions
Since the Gross–Pitaevskii equation is a nonlinear partial differential equation, exact solutions are hard to come by. As a result, solutions have to be approximated via a myriad of techniques.
Exact solutions
Free particle
The simplest exact solution is the free-particle solution, with :
This solution is often called the Hartree solution. Although it does satisfy the Gross–Pitaevskii equation, it leaves a gap in the energy spectrum due to the interaction:
According to the Hugenholtz–Pines theorem, an interacting Bose gas does not exhibit an energy gap (in the case of repulsive interactions).
Soliton
A one-dimensional soliton can form in a Bose–Einstein condensate, and depending upon whether the interaction is attractive or repulsive, there is either a bright or dark soliton. Both solitons are local disturbances in a condensate with a uniform background density.
If the BEC is repulsive, so that , then a possible solution of the Gross–Pitaevskii equation is
where is the value of the condensate wavefunction at , and is the coherence length (a.k.a. the healing length, see below). This solution represents the dark soliton, since there is a deficit of condensate in a space of nonzero density. The dark soliton is also a type of topological defect, since flips between positive and negative values across the origin, corresponding to a phase shift.
For the solution is
where the chemical potential is . This solution represents the bright soliton, since there is a concentration of condensate in a space of zero density.
Healing length
The healing length gives the minimum distance over which the order parameter can heal, which describes how quickly the wave function of the BEC can adjust to changes in the potential. If the condensate density grows from 0 to n within a distance ξ, the healing length can calculated by equating the
quantum pressure and the interaction energy:
The healing length must be much smaller than any length scale in the solution of the single-particle wavefunction. The healing length also determines the size of vortices that can form in a superfluid. It is the distance over which the wavefunction recovers from zero in the center of the vortex to the value in the bulk of the superfluid (hence the name "healing" length).
Variational solutions
In systems where an exact analytical solution may not be feasible, one can make a variational approximation. The basic idea is to make a variational ansatz for the wavefunction with free parameters, plug it into the free energy, and minimize the energy with respect to the free parameters.
Numerical solutions
Several numerical methods, such as the split-step Crank–Nicolson and Fourier spectral methods, have been used for solving GPE. There are also different Fortran and C programs for its solution for the contact interaction and long-range dipolar interaction.
Thomas–Fermi approximation
If the number of particles in a gas is very large, the interatomic interaction becomes large so that the kinetic energy term can be neglected in the Gross–Pitaevskii equation. This is called the Thomas–Fermi approximation and leads to the single-particle wavefunction
And the density profile is
In a harmonic trap (where the potential energy is quadratic with respect to displacement from the center), this gives a density profile commonly referred to as the "inverted parabola" density profile.
Bogoliubov approximation
Bogoliubov treatment of the Gross–Pitaevskii equation is a method that finds the elementary excitations of a Bose–Einstein condensate. To that purpose, the condensate wavefunction is approximated by a sum of the equilibrium wavefunction and a small perturbation :
Then this form is inserted in the time-dependent Gross–Pitaevskii equation and its complex conjugate, and linearized to first order in :
Assuming that
one finds the following coupled differential equations for and by taking the parts as independent components:
For a homogeneous system, i.e. for , one can get from the zeroth-order equation. Then we assume and to be plane waves of momentum , which leads to the energy spectrum
For large , the dispersion relation is quadratic in , as one would expect for usual non-interacting single-particle excitations. For small , the dispersion relation is linear:
with being the speed of sound in the condensate, also known as second sound. The fact that shows, according to Landau's criterion, that the condensate is a superfluid, meaning that if an object is moved in the condensate at a velocity inferior to s, it will not be energetically favorable to produce excitations, and the object will move without dissipation, which is a characteristic of a superfluid. Experiments have been done to prove this superfluidity of the condensate, using a tightly focused blue-detuned laser. The same dispersion relation is found when the condensate is described from a microscopical approach using the formalism of second quantization.
Superfluid in rotating helical potential
The optical potential well might be formed by two counterpropagating optical vortices with wavelengths , effective width and topological charge :
where . In cylindrical coordinate system the potential well have a remarkable double-helix geometry:
In a reference frame rotating with angular velocity , time-dependent Gross–Pitaevskii equation with helical potential is
where is the angular-momentum operator.
The solution for condensate wavefunction is a superposition of two phase-conjugated matter–wave vortices:
The macroscopically observable momentum of condensate is
where is number of atoms in condensate.
This means that atomic ensemble moves coherently along axis with group velocity whose direction is defined by signs of topological charge and angular velocity :
The angular momentum of helically trapped condensate is exactly zero:
Numerical modeling of cold atomic ensemble in spiral potential have shown the confinement of individual atomic trajectories within helical potential well.
Derivations and Generalisations
The Gross–Pitaevskii equation can also be derived as the semi-classical limit of the many body theory of s-wave interacting identical bosons represented in terms of coherent states. The semi-classical limit is reached for a large number of quanta, expressing the field theory either in the positive-P representation (generalised Glauber-Sudarshan P representation) or Wigner representation.
Finite-temperature effects can be treated within a generalised Gross–Pitaevskii equation by including scattering between condensate and noncondensate atoms, from which the Gross–Pitaevskii equation may be recovered in the low-temperature limit.
References
Further reading
External links
Trotter-Suzuki-MPI Trotter-Suzuki-MPI is a library for large-scale simulations based on the Trotter-Suzuki decomposition that can also address the Gross–Pitaevskii equation.
XMDS XMDS is a spectral partial differential equation library that can be used to solve the Gross–Pitaevskii equation.
Bose–Einstein condensates
Eponymous equations of physics
Superfluidity | Gross–Pitaevskii equation | [
"Physics",
"Chemistry",
"Materials_science"
] | 2,394 | [
"Bose–Einstein condensates",
"Physical phenomena",
"Phase transitions",
"Equations of physics",
"Phases of matter",
"Eponymous equations of physics",
"Superfluidity",
"Condensed matter physics",
"Exotic matter",
"Matter",
"Fluid dynamics"
] |
7,178,651 | https://en.wikipedia.org/wiki/Side%20population | A side population (SP) in flow cytometry is a sub-population of cells that is distinct from the main population on the basis of the markers employed. By definition, cells in a side population have distinguishing biological characteristics (for example, they may exhibit stem cell-like characteristics), but the exact nature of this distinction depends on the markers used in identifying the side population.
Examples
Side populations were first identified in hematopoietic stem cells by Dr. Margaret Goodell. SPs have been identified in hepatocellular carcinomas and may be the cells that efflux chemotherapy drugs, accounting for the resistance of cancer to chemotherapy.
Recent studies on testicular stem cells indicate that more than 40% of the SP (defined in this case as cells that show higher efflux of DNA-binding dye Hoechst 33342) was undifferentiated spermatogonia, while other differentiated fractions were represented by only 0.2%. SP cells can rapidly efflux lipophilic fluorescent dyes to produce a characteristic profile based on fluorescence-activated flow cytometric analysis. Previous studies have demonstrated SP cells in bone marrow obtained from patients with acute myeloid leukemia, suggesting that these cells might be candidate leukemic stem cells, and recent studies have found a SP of tumor progenitor cells in human solid tumors. These new data indicate that the ability of malignant SP cells to expel anticancer drugs may directly improve their survival and sustain their clonogenicity during exposure to cytostatic drugs, allowing disease recurrence when therapy is withdrawn. Identification of a tumor progenitor population with intrinsic mechanisms for cytostatic drug resistance might also provide clues for improved therapeutic intervention. The molecules involved in effluxing Hoechst 33342 are members of the ATP-binding cassette family, such as MDR1 (P-glycoprotein) and ABCG2.
References
Cell biology
Flow cytometry | Side population | [
"Chemistry",
"Biology"
] | 409 | [
"Cell biology",
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7,179,075 | https://en.wikipedia.org/wiki/American%20Welding%20Society | The American Welding Society (AWS) was founded in 1919 as a non-profit organization to advance the science, technology and application of welding and allied joining and cutting processes, including brazing, soldering and thermal spraying.
Headquartered in Doral, Florida, and led by a volunteer organization of officers and directors, AWS serves over 73,000 members worldwide and is composed of 22 Districts with 250 Sections and student chapters.
History
The roots of the American Welding Society stretch back to World War I, when the sudden demands of swiftly producing military equipment brought about the need for standardization of the manufacturing industry. An evolving metal joining process, welding, suddenly became very necessary to enhance the war effort. To ensure that industry took advantage of this technology, President Woodrow Wilson called upon a Harvard professor, Comfort A. Adams, to chair the Welding Committee of the Emergency Fleet Corp.
Welding performed well in the war effort and its success motivated Adams in 1919 to bring together industry leaders for the purpose of merging the Welding Committee of the Emergency Fleet Corp. and the National Welding Council into a new organization, the purpose of which was to provide dependable and objective information on the developing technology of welding. On March 28, 1919, the American Welding Society was born for that purpose, with Adams serving as its first President.
That first year the Society grew to 217 members; introduced the Journal of the American Welding Society, a technical publication with a life of one issue, but the precursor of the Welding Journal; found a home in the Engineering Societies Building in New York City; and established the foundation of the committee system for the production of its operating procedures and industry standards on welding. In 1920, the first local Section was organized in Philadelphia, Pennsylvania.
By 1922, the American Welding Society had held its first Annual Meeting. Attendees were told of the formation of Sections in eight cities, and also of the establishment of the Journal of the American Welding Society. However, the first meeting also called into discussion the growing financial issues surrounding the depression and proposed solutions to alleviate it. Financial reports delivered at the meeting stated an income for fiscal year ending March 31, 1922, of $12,683.74. The budget for fiscal year 1922-23 was projected at $15,540. It was clear more earnings were needed, so the Society turned to increasing membership numbers of advertising in the Journal as a solution.
Location
The American Welding Society's first headquarters were located in New York City, inside the Engineering Societies' Building. For 42 years the organization held all their business in this building, before finally making the move to the United Engineering Center, which was also in New York City. In 1971 the Society once again moved their headquarters – this time to Miami, Florida. The American Welding Society held this location for 30 years before buying its current property in Doral, Florida – only seven miles northwest of the old facility.
In August 2012 the American Welding Society moved from their longtime headquarters just outside Coral Gables to their current location in Doral. During the grand opening of the new building, AWS President William Rice said "Our newly renovated five-story building in Doral offers us exactly what we need. It gives us more than three times the office and meeting space of our previous headquarters, and it provides room for our board, committee, and educational activities.”
The lobby of the headquarters features a bronze sculpture created by sculptor Gregory Johnson and donated to the American Welding Society by President Rice and his wife Cherry.
Welding Journal
The publication currently known as the Welding Journal was born in October 1919 with a different name. The Journal of the American Welding Society was its original title – and it had just one issue under this name. In the first publication, American Welding Society President Comfort A. Adams wrote, "The American Bureau of Welding is the authoritative body to establish the facts. To make the most use of the facts, however, requires another sort of machinery and the organization that does this is the American Welding Society. Its function is not to supply the knowledge but to spread it and assist in putting it to practical uses. It is the Society, for instance, which publishes this Journal, which will push matters of importance to welding and which will open out new fields for its use. It holds regular meetings to discuss matters relating to welding, to act upon the recommendation of the Bureau and to initiate further activities. This division of the work, while it has created some confusion on account of the similarity of the names, is a logical one, and will be found effective in operating as was clearly indicated by the experience with the old Welding Committee."
Operating costs were too high for the Journal, and it was not until 1922 that the publication was reborn under its current name thanks to advertising earnings.
The society explained the advertising move in their first issue of the newly named Welding Journal. "Advertising is also included in this issue, as it was impossible to continue monthly publication without increased revenue. The dues from members of which the National Organization retains half (the other half being returned to local sections) is barely sufficient to pay the ordinary expenses of the Society. Moreover, several members of the Board of Directors feel that these advertisements are of interest to our members and add to the value of the Journal."
Since the move to advertising, the Welding Journal has been published continually and continues to be an resource for issues and advancements concerning all types of materials joining, metal fabrication, and construction. It is offered as a benefit to members of the Society, and includes information of the latest products, trends, technology, and events; including articles covering everything from testing and inspection, maintenance and repair, design, training, personal safety, and brazing and soldering.
The Welding Journal has earned more than 60 editorial and design awards, including multiple Charlie Awards from the Florida Magazine Association (FMA), and Tabbie Awards from the Trade Association Business Publications International (TABPI).
The Society now also publishes the Welding Journal en Español – a free quarterly publication containing tailored articles written by and for Mexican and Latin American professionals. The Welding Journal en Español has a circulation of 10,000 printed copies and 40,000 digital copies. Along with this publication, the Welding Journal em Português is a magazine distributed in Brazil to coincide with the Brazil Welding Show that takes place every two years in São Paulo, Brazil.
Certification
The American Welding Society offers a number of certification programs that recognize and document expertise and knowledge in specific welding-related disciplines, including:
Certified Welding Inspector
Senior Certified Welding Inspector
Certified Welding Educator
Certified Radiographic Interpreter
Certified Welding Supervisor
Certified Welding Sales Representative
Certified Welding Engineer
Certified Welder
Certified Robotic Arc Welding
Since the Certified Welding Inspector (CWI) program was introduced in 1976, AWS has certified over 100,000 welding inspectors alone, plus thousands more working professionals across the other certification categories. Certification is accomplished through testing and evaluation of corresponding procedures. The Radiographic Interpretation Certification, for example, includes a detailed general knowledge exam, a test of specific information from the AWS code book on radiographic quality and interpretation, and a practical exam testing the individual's ability to read radiographic films. Most AWS certifications are typically renewed after a period of three years, and are required to satisfy re-certification requirements every nine years.
Welders are required to take a qualification test at an AWS Accredited Testing Facility. Welders must mail their qualification test record to AWS with a completed AWS Welder Application in order to have an AWS certification issued. AWS Welders are required to submit a Maintenance of Welder Certification Formto renew their certifications every six months.
Endorsements
Endorsements are supplemental inspection credentials available to all AWS Certified Welding Inspectors (CWIs) and Senior Certified Welding Inspectors (SCWIs) to enhance an individual’s credentials. The examinations offered as endorsements to the CWI/SCWI programs are also offered as stand-alone exams to non-CWIs/SCWIs who wish to enhance their educational background.
Below are the available endorsement certifications that AWS offers .
D1.1 Structural Steel
D1.2 Structural Aluminum
D1.5 Welding
D15.1 Railroad
D17.1 Aerospace
API 1104 Pipeline
Structural Drawing Reading
Structural Bolting Inspection
ASME Pressure Piping B31.1 and B31.3
ASME Pressure Vessel Section VIII, Div. 1
Accredited Test Facilities
The American Welding Society also certifies the Accredited Test Facilities (ATF) which play an integral part in the operation of their Certification program. The ATF program establishes minimum requirements for test facilities, their personnel and equipment to qualify for accreditation to test and qualify welders. This program is open to all qualified test facilities that may be a part of an independent laboratory, manufacturing plant, educational institution, or other entity. American Welding Society ATFs are listed on the official AWS website and advertised in the American Welding Society's Welding Journal magazine.
The ATF program requires that a facility implements a quality assurance program that meets the requirements established in the AWS QC4-89, Standard for the Accreditation of Testing Facilities. The requirements include that the facility has a Quality Manual that controls the activities related to the testing of welders in the facility according to AWS QC7, Standard for AWS Certified Welders. The facility must also have a CWI on staff or contracted to perform the welder qualification tests.
The American Welding Society explains the benefits of the ATF program on their website by writing "Entrusting welder certification to ATF specialists makes good business sense for contractors and fabricators. Companies are increasingly realizing the shortcomings of self-qualification and switching to AWS Accredited Test Facilities to test and qualify their welders. ATFs help them to save money, improve productivity, and reduce liability by entrusting their welder certification to the experts."
Certified Welding Fabricator
American Welding Society certifications are not only available to individuals. Companies may also become an official AWS Certified Welding Fabricator (CWF). The American Welding Society describes the program as being "designed to recognize those select companies who prove they have the resources, procedures, and personnel to apply a quality management system to the welding fabrication activities."
The American Institute of Steel Construction (AISC) and the American Welding Society have established a reciprocity agreement whereby AISC Certified Fabricators are also eligible to receive certification as an AWS Certified Welding Fabricator. The AISC certification program criteria fully satisfy the AWS Welding Fabricator Certification program requirements. AISC Fabricators that hold current building structures and/or bridge certification may apply to AWS and pay a minimal fee to also attain the AWS Certified Welding Fabricator certification.
Membership
As of April 2015, the American Welding Society had approximately 73,000 members around the world. The Society offers four types of membership options:
Individual member
Welder member
Corporate member
Student member
AWS codes and specifications
AWS publishes codes on multiple aspects of welding and materials joining. The code books are assigned specific letters and numbers for easy reference, and many welders will refer to a specific code letter/number combination when referring to the code book. Different welding methodologies, inspection methods, and metals are published under different codes. For example, AWS B1.11 explains how to visually examine welds; AWS B2.1-1-004 explains welding carbon steel of thickness range of 18 through 10 gauge with semiautomatic metal gas arc welding; and AWS C2.20/C2.20M explains metalized zinc cathodic protection systems. Some codes also describe the standards used by AWS to certify welders, inspectors, and welding educators. All codes are available in hard copy, and in recent years AWS has started to make most codes available online.
A very influential AWS code is AWS D1.1, which covers all general requirements for structural welding. This code has been adopted by ANSI as a National Standard in the United States.
Sections
The American Welding Society extends its reach into local communities through the use of their local sections and student chapters. The Society is composed of 250 sections around the world, and AWS describes them as "the very heart and foundation of AWS."
Section members have the opportunity to network, gain knowledge, and get answers to welding questions from Section members with years of experience. Professional Development Hours may be earned by attending technical meetings, and other planned activities may include educational seminars, plant tours, social events, student programs, community projects and more.
List of American Welding Society sections
AWS Foundation
The American Welding Society Foundation was founded in 1989 to support research and education in welding and related technologies. It is committed to annually awarding fellowships to deserving graduate students for important research in areas important to the requirements of industry. Accordingly, each year the AWS Foundation administers two $25,000 grants – matched in kind by the participating universities. The award of scholarships to vocational and undergraduate college students is also a high priority.
AWS awards
The Image of Welding Awards, presented by the American Welding Society and WEMCO, an association of welding manufacturers, recognize individuals and organizations that have shown exemplary dedication to promoting the image of welding in their communities. Starting in 2015, the awards will now be known as the Excellence in Welding Awards. Recipients of this award will receive a zinc die-cast, 24k gold statue designed by New York firm, Society Awards.
Standing committees
The American Welding Society also has several standing committees, or partner organizations, which help promote and advance different facets of the welding industry. These include:
BSMC – Brazing & Soldering Manufacturers Committee
ITSA – International Thermal Spray Association
RWMA – Resistance Welding Manufacturing Alliance
WEMCO – An association of Welding Manufacturers
Officers
See also
List of welding codes
International Institute of Welding
American Society of Mechanical Engineers
References
American engineering organizations
Welding organizations
Non-profit organizations based in Florida
Organizations established in 1919
Organizations based in Miami | American Welding Society | [
"Engineering"
] | 2,818 | [
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7,179,232 | https://en.wikipedia.org/wiki/Design%20Piracy%20Prohibition%20Act | The Design Piracy Prohibition Act, , , and , were bills of the same name introduced in the United States Congress that would have amended Title 17 of the United States Code to provide sui generis protection to fashion designs for a period of three years. The Acts would have extended protection to "the appearance as a whole of an article of apparel, including its ornamentation," with "apparel" defined to include "men's, women's, or children's clothing, including undergarments, outerwear, gloves, footwear, and headgear;" "handbags, purses, and tote bags;" belts, and eyeglass frames. In order to receive the three-year term of protection, the designer would be required to register with the U.S. Copyright Office within three months of going public with the design.
H.R. 2511, 112th Congress
H.R. 2511 was introduced July 13, 2011, by Representative Robert Goodlatte [R-VA6] with thirteen co-sponsors. On August 25, 2011, the U.S. House Committee on the Judiciary referred the Bill to the U.S. House Subcommittee on Courts, the Internet, and Intellectual Property.
http://www.govtrack.us/congress/bill.xpd?bill=h112-2511
H.R. 2033, 110th Congress
H.R. 2033 was introduced April 25, 2007, by Representative Bill Delahunt with fourteen co-sponsors. On May 4, 2007, the U.S. House Committee on the Judiciary referred the Bill to the U.S. House Subcommittee on Courts, the Internet, and Intellectual Property. A hearing was held February 14, 2008, but the bill never made it out of the subcommittee.
S. 1957, 110th Congress
S. 1957 was introduced on August 2, 2007, in Washington, D.C. by Senator Charles Schumer (D-NY) with ten co-sponsors. The bill was referred to the Senate Committee on the Judiciary but progressed no further.
H.R. 2196, 111th Congress
H.R. 2196 was introduced on April 30, 2009, by Representative Delahunt and twenty-three co-sponsors. The bill was referred to the House Committee on the Judiciary on the same day and then stalled in committee.
Current Status of Fashion Design Protection
Currently, fashion may be protected by copyright only to the extent that its shape is non-utilitarian enough to qualify as a creative "sculpture," or to the extent that a design, pattern, or image on the clothing qualifies as "pictorial" or "graphic." While current laws against counterfeit goods do provide some protection for designers, this is so only when the trademark is used and not when merely the design is copied under a different label. In addition, fashion may be protected by design patents if the requirements for patentability are met. To be patentable an ornamental design must be new, original and non-obvious. The United States Patent and Trademark Office website (www.uspto.gov) has a searchable database of patents, and includes patents on apparel in class D2, carrying articles in class D3, and eyeglass frames in class D16. Technological advances to the means of textile and garment production, as well as increases in the number of distribution channels and the availability of cheap labor in emerging economies have enabled those who would copy these designs to do so quickly and inexpensively. Legislation targeting design piracy has already been enacted in Europe, India, and Japan.
Criticism
Critics claim that, contrary to the bill's claims, the bill will actually harm independent fashion designers. The majority of independent designers do not have the litigation funds to effectively challenge big business should they be accused of copyright infringement. Furthermore, because distributors of accused designs can be penalized as well as the designer, distributors of clothing will become very wary of new designs unless the designer has adequate funds, influence, and power to hire skilled and effective lawyers. Pattern companies frequently utilize prevailing trends; so they too are vulnerable. Because of the legal risks of producing fashion patterns, fewer people will sew their own clothing, and fabric and sewing stores will suffer losses as well. As evidence of the bill's hypocrisy, critics point to how one of the most vocal supporters of the bill, Diane von Fürstenberg, was recently caught copying and distributing a piece of clothing originally designed by an independent Canadian designer. Critics also argue that the industry is already thriving commercially and encourages innovation. They point attention to the concept that originality in fashion design is too insubstantial for copyright law to distinguish protected elements from non-protected elements, and that extending copyright protection would stifle independent designers while giving powerful, big-business fashion houses a near-monopoly.
Related Bills
H.R. 5055, 109th Congress: To Amend Title 17, United States Code, to Provide Protection for Fashion Design
H.R. 5055 was introduced March 30, 2006, by Representative Robert W. Goodlatte (R-Va.), with six co-sponsors from both parties. The bill was referred by the U.S. House Committee on the Judiciary to the U.S. House Subcommittee on Courts, the Internet, and Intellectual Property.
The subcommittee held a hearing on the bill on July 27, 2006, at which there was disagreement among legal experts as well as representatives of the fashion industry as to whether there was a need for copyright protection. Proponents of the Act claimed that new technology threatened American designers' ability to compete with the products of lower-cost countries, because the distribution of images of new designs and the automation of copying and manufacturing could occur within hours. They additionally pointed out that the United States was the exception among western nations in failing to protect designs.
S. 3728, 111th Congress: Innovative Design Protection and Piracy Prevention Act
S.3728 was introduced on August 5, 2010, by Senator Chuck Schumer with ten co-sponsors. On December 1, 2010, the Senate Committee on the Judiciary voted unanimously for the bill to proceed to the Senate floor. This is the furthest that any of the design bills has progressed since 2006.
Under the IDPPPA, a copy of a design would have infringed if it was found to be "substantially identical" to the original work with little to no changes to set that design apart. Penalties for false representation would have been increased from $500 to $5,000 and from $1,000 to $10,000. "Apparel" items that would be protected by this Act include women's, men's, and children's clothing as well as luggage, handbags, wallets and eyeglass frames. A "fashion design" under the IDPPPA would be defined as an entire article of apparel including its embellishment and also includes elements of the original apparel that are the creative work of the original designer and are unique.
Supporters argue that this act would create more protection for fashion designers. Opponents have argued that the bill would "bring more lawyers into every step of the design process," outlaw "inspiration and creativity," prevent "unrestricted use of works in the public domain," and "slow down the fast-paced design process." Some designers have supported the IDPPPA for protecting their current and future fashion designs. For example, Kurt Courtney of the AAFA has praised the bill as a "great compromise and a product of hard work," but added that its effects will largely be seen in court cases involving the bill.
S. 3523, 112th Congress: Innovative Design Protection Act
S.3523 was introduced on September 10, 2012, by Senator Chuck Schumer with ten co-sponsors. On September 20, 2012, the Senate Committee on the Judiciary voted for the bill to proceed to the Senate floor without amendment.
See also
Sara R. Ellis, Copyrighting Couture: An Examination of Fashion Design Protection and Why the DPPA and IDPPPA are a Step Towards the Solution to Counterfeit Chic, 78 Tenn. L. Rev. 163 (2010), available at http://ssrn.com/abstract=1735745.
Witnesses Clash on Need for Granting Copyright Protection to Fashion Designs, Anandashankar Mazumdar. BNA's Patent, Trademark & Copyright Journal, August 4, 2006.
Intellectual property legislation pending in the United States Congress
THOMAS
References
External links
Full text of Design Piracy Prohibition Act, H.R. 5055
Bc.edu
Uspto.gov: Index to the United States Patent Classification (USPC) System
Uspto.gov: Guide to Filing a Design Patent Application
Will the Fashion Copyright Bill Stifle Innovation?
Fashion design
United States proposed federal intellectual property legislation
Design | Design Piracy Prohibition Act | [
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7,180,512 | https://en.wikipedia.org/wiki/Nonequilibrium%20Gas%20and%20Plasma%20Dynamics%20Laboratory | The Nonequilibrium Gas and Plasma Dynamics Laboratory (NGPDL) at the Aerospace Engineering Department of the University of Colorado Boulder is headed by Professor Iain D. Boyd and performs research of nonequilibrium gases and plasmas involving the development of physical models for various gas systems of interest, numerical algorithms on the latest supercomputers, and the application of challenging flows for several exciting projects. The lab places a great deal of emphasis on comparison of simulation with external experimental and theoretical results, having ongoing collaborative studies with colleagues at the University of Michigan such as the Plasmadynamics and Electric Propulsion Laboratory, other universities, and government laboratories such as NASA, United States Air Force Research Laboratory, and the United States Department of Defense.
Current research areas of the NGPDL include electric propulsion, hypersonic aerothermodynamics, flows involving very small length scales (MEMS devices), and materials processing (jets used in deposition thin films for advanced materials). Due to nonequilibrium effects, these flows cannot always be computed accurately with the macroscopic equations of gas dynamics and plasma physics. Instead, the lab has adopted a microscopic approach in which the atoms/molecules in a gas and the ions/electrons in a plasma are simulated on computationally using a large number of model particles within sophisticated Monte Carlo methods. The lab has developed a general 2D/axi-symmetric/3D code, MONACO, for simulating nonequilibrium neutral flows that can run either on scalar workstations or in a parallel computing environment.
The lab also has developed a general 2D/axi-symmetric/3D code, LeMANS, to numerically solve the Navier-Stokes equations using computational fluid dynamics when the Knudsen number is sufficiently small. This allows lab members to explore flows that would otherwise be too computationally expensive with a particle method. Work is currently being done to combine the two codes into a hybrid that uses MONACO when the flow is in the collisional nonequilibrium regime and LeMANS when the flow can be considered continuous.
Current and past plasma and nonequilibrium flow projects include simulation of ion thrusters, Hall effect thrusters, and pulsed plasma thrusters) as well as numerous NASA contracts to study reentry aerothermodynamics for space vehicles, including the Crew Exploration Vehicle. Other plasma research includes modeling wall ablation from directed energy weapons and the plasma-propellant interaction in electrothermal chemical guns.
Official website
https://www.colorado.edu/lab/ngpdl/
University of Michigan
Aerospace engineering organizations
Plasma physics facilities
Plasma processing
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7,180,591 | https://en.wikipedia.org/wiki/Pressure%20head | In fluid mechanics, pressure head is the height of a liquid column that corresponds to a particular pressure exerted by the liquid column on the base of its container. It may also be called static pressure head or simply static head (but not static head pressure).
Mathematically this is expressed as:
where
is pressure head (which is actually a length, typically in units of meters or centimetres of water)
is fluid pressure (i.e. force per unit area, typically expressed in pascals)
is the specific weight (i.e. force per unit volume, typically expressed in N/m3 units)
is the density of the fluid (i.e. mass per unit volume, typically expressed in kg/m3)
is acceleration due to gravity (i.e. rate of change of velocity, expressed in m/s2).
Note that in this equation, the pressure term may be gauge pressure or absolute pressure, depending on the design of the container and whether it is open to the ambient air or sealed without air.
Head equation
Pressure head is a component of hydraulic head, in which it is combined with elevation head. When considering dynamic (flowing) systems, there is a third term needed: velocity head. Thus, the three terms of velocity head, elevation head, and pressure head appear in the head equation derived from the Bernoulli equation for incompressible fluids:
where
is velocity head,
is elevation head,
is pressure head, and
is a constant for the system
Practical uses for pressure head
Fluid flow is measured with a wide variety of instruments. The venturi meter in the diagram on the left shows two columns of a measurement fluid at different heights. The height of each column of fluid is proportional to the pressure of the fluid. To demonstrate a classical measurement of pressure head, we could hypothetically replace the working fluid with another fluid having different physical properties.
For example, if the original fluid was water and we replaced it with mercury at the same pressure, we would expect to see a rather different value for pressure head. In fact the specific weight of water is 9.8 kN/m3 and the specific weight of mercury is 133 kN/m3. So, for any particular measurement of pressure head, the height of a column of water will be about [133/9.8 = 13.6] 13.6 times taller than a column of mercury would be. So if a water column meter reads "13.6 cm H2O", then an equivalent measurement is "1.00 cm Hg".
This example demonstrates why there is some confusion surrounding pressure head and its relationship to pressure. Scientists frequently use columns of water (or mercury) to measure pressure (manometric pressure measurement), since for a given fluid, pressure head is proportional to pressure. Measuring pressure in units of "mm of mercury" or "inches of water" makes sense for instrumentation, but these raw measurements of head must frequently be converted to more convenient pressure units using the equations above to solve for pressure.
In summary pressure head is a measurement of length, which can be converted to the units of pressure (force per unit area), as long as strict attention is paid to the density of the measurement fluid and the local value of g.
Implications for gravitational anomalies on ψ
We would normally use pressure head calculations in areas in which is constant. However, if the gravitational field fluctuates, we can prove that pressure head fluctuates with it.
If we consider what would happen if gravity decreases, we would expect the fluid in the venturi meter shown above to withdraw from the pipe up into the vertical columns. Pressure head is increased.
In the case of weightlessness, the pressure head approaches infinity. Fluid in the pipe may "leak out" of the top of the vertical columns (assuming ).
To simulate negative gravity, we could turn the venturi meter shown above upside down. In this case gravity is negative, and we would expect the fluid in the pipe to "pour out" the vertical columns. Pressure head is negative (assuming ).
If and , we observe that the pressure head is also negative, and the ambient air is sucked into the columns shown in the venturi meter above. This is called a siphon, and is caused by a partial vacuum inside the vertical columns. In many venturis, the column on the left has fluid in it (), while only the column on the right is a siphon ().
If and , we observe that the pressure head is again positive, predicting that the venturi meter shown above would look the same, only upside down. In this situation, gravity causes the working fluid to plug the siphon holes, but the fluid does not leak out because the ambient pressure is greater than the pressure in the pipe.
The above situations imply that the Bernoulli equation, from which we obtain static pressure head, is extremely versatile.
Applications
Static
A mercury barometer is one of the classic uses of static pressure head. Such barometers are an enclosed column of mercury standing vertically with gradations on the tube. The lower end of the tube is bathed in a pool of mercury open to the ambient to measure the local atmospheric pressure. The reading of a mercury barometer (in mm of Hg, for example) can be converted into an absolute pressure using the above equations.
If we had a column of mercury 767 mm high, we could calculate the atmospheric pressure as (767 mm)•(133 kN/m3) = 102 kPa. See the torr, millimeter of mercury, and pascal (unit) articles for barometric pressure measurements at standard conditions.
Differential
The venturi meter and manometer is a common type of flow meter which can be used in many fluid applications to convert differential pressure heads into volumetric flow rate, linear fluid speed, or mass flow rate using Bernoulli's principle. The reading of these meters (in inches of water, for example) can be converted into a differential, or gauge pressure, using the above equations.
Velocity head
The pressure of a fluid is different when it flows than when it is not flowing. This is why static pressure and dynamic pressure are never the same in a system in which the fluid is in motion. This pressure difference arises from a change in fluid velocity that produces velocity head, which is a term of the Bernoulli equation that is zero when there is no bulk motion of the fluid. In the picture on the right, the pressure differential is entirely due to the change in velocity head of the fluid, but it can be measured as a pressure head because of the Bernoulli principle. If, on the other hand, we could measure the velocity of the fluid, the pressure head could be calculated from the velocity head. See the Derivations of Bernoulli equation.
See also
Centimetre of water
Pressure measurement
Hydraulic head or velocity head, which includes a component of pressure head
Venturi effect
External links
Engineering Toolbox article on Specific Weight
Engineering Toolbox article on Static Pressure Head
Fluid dynamics
Pressure | Pressure head | [
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7,180,756 | https://en.wikipedia.org/wiki/Methyllycaconitine | Methyllycaconitine (MLA) is a diterpenoid alkaloid found in many species of Delphinium (larkspurs). In common with many other diterpenoid alkaloids, it is toxic to animals, although the acute toxicity varies with species. Methyllycaconitine was identified one of the principal toxins in larkspurs responsible for livestock poisoning in the mountain rangelands of North America. Methyllycaconitine has been explored as a possible therapeutic agent for the treatment of spastic paralysis, and it has been shown to have insecticidal properties. It has become an important molecular probe for studying the pharmacology of the nicotinic acetylcholine receptor.
Isolation
MLA was first isolated from Delphinium brownii, Rydb. Presumably because he did not obtain the compound in sufficiently pure form, Manske declined to give it a name. The name "methyl-lycaconitine" was assigned by John Goodson, working at the Wellcome Chemical Research Laboratories in London, England, when he isolated the alkaloid, in purer form, from seeds of Delphinium elatum, L. in 1943.
A more modern isolation procedure is described by Pelletier and his co-workers, who used seeds of the "garden larkspur", Consolida ambigua (also referred to as Delphinium ajacis) as their plant source.
Structure determination
The complete molecular structure for MLA, correct in all but one detail, was first published by Kuzovkov and Platonova in 1959. This structure, supported in part by X-ray crystallography (considered usually to be a "definitive" analytical technique) of a chemical derivative of MLA performed by Maria Przybylska, was accepted as correct until the early 1980s. The stereochemistry of the methoxy group at C-1 from the β- to α- configuration has been determined. Thus any drawing of MLA appearing before Pelletier's 1981 paper will show the structure with the incorrect stereochemistry at C-1.
Chemistry
Synonyms
[1α,4(S),6β,14α,16β]-20-Ethyl-1,6,14,16-tetramethoxy-4-[[[2-(3-methyl-2,5-dioxo-1-pyrrolidinyl)benzoyl]oxy]methyl]aconitane-7,8-diol; also referred to, incorrectly, as "N-methyl lycaconitine" in a few publications.
Physico-chemical properties
MLA is soluble in chloroform, but does not dissolve well in water.
The free base of MLA has not been obtained in crystalline form, and in its amorphous form it melts ultimately at 128 °C; the hydriodide salt has a melting point of 201 °C.; the perchlorate salt melts at 195 °C
The citrate salt is the most common form in which MLA is currently available commercially.
A pKa does not seem to have been recorded for MLA, but it is considered to be a weak base because it can be readily extracted into diethyl ether from an aqueous solution at pH 7.5-8.
The optical rotation of the free base, [α]D was found to be +49° in alcohol.
Molecular structure
Although commonly referred to as a "diterpenoid" alkaloid, MLA is, strictly speaking, a nor-diterpenoid, since its carbon skeleton only contains 19 C atoms, one having been deleted somewhere during its biosynthesis.
Otherwise, the MLA molecule comprises a tertiary amine, two tertiary alcohols, four methyl ether groups, and a complex ester based on anthranilic acid and methylsuccinic acid. This N-(2-carboxyphenyl)-methylsuccinamido-ester is quite rare amongst natural products.
Synthesis
As of April, 2012 no total synthesis of MLA has been reported. A semi-synthesis of MLA, starting from its "parent" amino-alcohol, lycoctonine (obtained by simple alkaline hydrolysis of natural MLA ) was reported in 1994.
Pharmacology
In many respects, the pharmacology of MLA closely resembles that of the classical neuromuscular blocker, d-tubocurarine. The "curare-like" properties of MLA seem to have been first mentioned in 1958 by Kuzovkov and Bocharnikova, working at the Ordzhinikidze All-Union Institute for Scientific Research in Pharmaceutical Chemistry, in the former USSR. A detailed paper on the pharmacology of MLA (in the form of its hydriodide salt, given the drug name "mellictine") in classical animal preparations was published from the same Institute in the following year by Dozortseva.
They revealed that MLA blocked neuromuscular transmission in skeletal muscle, but not smooth muscle, and had some ganglion-blocking action. Such properties are characteristic of an antagonist of acetylcholine exerting its effects at nicotinic, but not muscarinic sites.
In the rat phrenic nerve-diaphragm preparation, for example, a 2 x 10−5M concentration of MLA produced a 50% decrease in response, and total inhibition was caused by a 3 x 10−5M concentration of the drug. In this preparation, MLA-treated muscle responded normally to direct electrical stimulation, but the inhibition of contractions was only partially antagonized by physostigmine. Similar results were obtained with frog nerve-muscle preparations, in which it was shown that MLA blocked response of the gastrocnemius muscle to electrical stimulation of the sciatic nerve, inhibited post-synaptic action potentials in the sartorius muscle elicited by stimulation of the sciatic nerve, and reduced the amplitude of miniature end-plate potentials in the extensor digitus IV muscle.
Ganglion-blocking effects of MLA were observed using the cat nictitating membrane preparation: complete inhibition of the response was produced by 4 mg/kg of "mellictine" given intravenously.
No significant effects were produced by the drug in smooth muscle preparations from rabbit, guinea pig or cat, indicating the lack of activity at typically muscarinic sites. In electrically stimulated guinea pig ileum, for example, contractions were unaffected by a concentration of 5 x 10−4M of MLA.
A more detailed summary of the above data, together with much related material, may be found in a review written by Kip Panter and collaborators at USDA-ARS laboratories in Utah and California.
A significant advance was made towards understanding the pharmacology of MLA when Jennings and co-workers at the American Cyanamid Company reported that MLA (as its citrate salt) strongly inhibited the binding of tritiated propionyl-α-bungarotoxin to a receptor preparation from house-fly heads, with a Ki of ~ 2.5 x 10−10M. Subsequently, Macallan and his co-workers showed that MLA also competed with 125I-α-bungarotoxin (Ki ~1 x 10−9M) and tritiated (−)-nicotine (Ki ~4 x 10−6M) in a receptor preparation from rat brain. These workers also reported that MLA displaced125I-α-bungarotoxin from purified Torpedo (electric ray) nicotinic acetylcholine receptors (nAChRs) with a Ki ~1 x 10−6M. Similar experiments performed later by Ward et al. showed that MLA bound to nAChRs extracted from human muscle with a Ki of ~8 x 10−6M; it was also reported that MLA, at a concentration of 10−4M, had no affinity for muscarinic AChRs, as labeled by tritiated quinuclidinyl benzilate, from rat brain.
Further details about the binding of MLA to nAChRs were presented by Wonnacott and her co-workers, who provided evidence that MLA bound preferentially to different sub-units, as expressed in Xenopus frog oocytes, of the nAChR cloned from avian DNA: MLA was found to have an IC50 of ~8 x 10−8M at α3β2 and ~7 x 10−7M at α4β2 receptor sub-types. Although it was also established that MLA bound strongly to α7 sub-types, experimental difficulties precluded the determination of an IC50. MLA displaced 125I-α-bungarotoxin from α7 receptors cloned from the human K28 cell line, with a Ki of ~ 1 x 10−8.
One last milestone in the ongoing saga of MLA pharmacology (there are, as of April 2012, approximately 660 references to articles in journals covered by PubMed) to be mentioned is the characterization of the receptor-interactions of tritium-labeled MLA..
The crystal structure has been determined of a complex between MLA and an AChBP isolated from the salt-water snail, Aplysia californica.
Toxicology
The toxicology of MLA has been studied largely in the context of livestock poisoning by wild larkspurs. The seminal work by John Jacyno and Mike Benn at the University of Calgary in Canada showed that MLA was most likely to be the agent responsible for the toxicity of a local larkspur, D. brownii, and provided some preliminary acute toxicity data in several animal species. These LD50s are as follows: mouse, 3–5 mg/kg; frog, 3–4 mg/kg; rabbit, 2–3 mg/kg (after parenteral administration). Cats appeared to have comparable susceptibility to rabbits, whereas dogs were ~ 1.5 x more sensitive. These early observations have been comprehensively extended, The LD50 of MLA is estimated to be ~10 mg/kg in sheep, ~ 5 mg/kg in rats, and ~2 mg/kg in cattle.
Although most LD50s are usually determined from parenteral administration of the test drug, MLA is also active when taken orally.
Signs of toxicity in calves, sheep, rats and mice, at low doses, included agitation, respiratory difficulty, and loss of motor control; symptoms appeared within 2–3 minutes of injection, and disappeared within 10 minutes. Doses large enough to produce collapse also caused an increase in heart and respiration rates, as well as tremor, with significant convulsions evident in mice and rats, but not in cattle or sheep. In cases where death seemed imminent, the poisoning in sheep could be counteracted by the i.v. administration of neostigmine and atropine, whereas poisoning in calves was reversed by the administration of physostigmine. In animals that were allowed to die, death appeared to be the result of complete motor paralysis and respiratory arrest.
It is worth noting that although a LD50 for man is not available, the clinical studies of Kabelyanskaya showed that an oral dose of 0.02 g of MLA hydriodide ("mellictine") might be given to patients up to 5 times per day, over the course of 1 month. However, some subjects could only tolerate single doses of 0.02 g per day without experiencing side-effects.
Structure-Activity relationships
The earliest observation on a relationship between the molecular structure of MLA and a biological activity concerned the effect of the C-18 ester group on acute toxicity. When this group was hydrolyzed, the resulting amino-alcohol (named lycoctonine as a consequence of its natural occurrence) was found to be much less poisonous to animals than was MLA. Lycoctonine is more than 100x less toxic than MLA.
In other functional pharmacological assays, lycoctonine resembled MLA qualitatively but was roughly ten times less potent.
When compared in nAChR-binding studies, MLA was found to compete for 125I-α-bungarotoxin binding sites (i.e. α7 sub-types) over 1000x more strongly than did lycoctonine.
If the succinimide ring is deleted so as to leave only the -NH2 group attached to the benzene ring (as in the alkaloid anthranoyllycoctonine, which also occurs naturally), the resulting compound is intermediate between MLA and lycoctonine in potency and toxicity: it is less acutely toxic than MLA by a factor of about 4, but its affinity for 125I-α-bungarotoxin binding sites is over 200x lower than that of MLA.
If the -NH2 group of anthranoyllycoctonine is removed, giving the compound lycoctonine-18-O-benzoate, the affinity for α7 receptors, as well as for α4β2 receptors is reduced by about a factor of 10 in comparison to MLA. When compared with MLA in the rat phrenic nerve-diaphragm assay, lycoctonine-18-O-benzoate was also about 10x less potent, and a similar reduction in potency was observed in an electrophysiological study involving frog extensor muscle.
Even the absence of the methyl group from the methylsuccinimido- ring, as in the alkaloid lycaconitine, reduces the affinity for α7 receptors by a factor of about 20,> but in this case affinity for α4β2 receptors is not significantly changed in comparison with MLA.
Another approach that has been explored in the attempt to elucidate structure-activity relationships in MLA has been to start with 2-(methylsuccinimido)-benzoic acid (the carboxylic acid produced when MLA is split at the C-18 ester group) and to esterify it with various alcohols and amino-alcohols that might be considered as "molecular fragments" of MLA. None of these compounds showed any significant degree of the biological actions characteristic of MLA, however, in the limited number of assays to which they were subjected.
Therapeutic applications
MLA has been used for treating a variety of neurological disorders, although there are no references to such use in the last few decades.
MLA might be useful in reducing nicotine reward without precipitating symptoms of nicotine withdrawal. This suggestion was made on the basis of experiments in which intraperitoneal doses of ~4 mg/kg and 8 mg/kg of MLA significantly reduced nicotine self-administration in rats.
It has been suggested that MLA had potential in the treatment of cannabis dependence. However, this suggestion was apparently based only on work by Solinas et al. who showed that doses of 0.3-5.6 mg/kg, i.p., in rats, dose-dependently antagonized the discriminative-stimulus effects of 3 mg/kg THC.
Given that the early Soviet work with "mellictine" indicated that as little as ~0.2-0.3 mg/kg, orally, in man (assuming a weight of 60–70 kg, for the sake of making the dose conversion) could produce symptoms of toxicity, and that oral administration of most drugs typically requires more drug than parenteral administration, it is uncertain if MLA will prove to be a practical treatment for either nicotine or cannabis addiction, based on the effective doses required in the rat experiments.
Insecticidal action
Jennings and co-workers, in addition to making their key observations (see Pharmacology above) about the receptor-binding of MLA, found it to be toxic (50+% mortality) to the following insect species: Empoasca abrupta (at 100 ppm), Heliothis virescens (at 1000 ppm), Musca domestica (at 1000 ppm) and Spodoptera eridana (at 1000 ppm). Species which were not significantly affected by MLA were: Anopheles quadrimaculatus, Aphis fabae, Diabrotica undecimpunctuata howardi and Tetranychus urticae. MLA also behaved as a feeding deterrent, with an LC50 of ~300 ppm, to Spodoptera larvae feeding on bean leaves.
References
External links
Plant extract may block cannabis addiction
Diterpene alkaloids
Benzoate esters
Ethers
Tertiary alcohols
Succinimides
Terpenes and terpenoids
Nicotinic antagonists
Plant toxins | Methyllycaconitine | [
"Chemistry"
] | 3,476 | [
"Biomolecules by chemical classification",
"Chemical ecology",
"Natural products",
"Functional groups",
"Plant toxins",
"Organic compounds",
"Ethers",
"Terpenes and terpenoids"
] |
7,180,897 | https://en.wikipedia.org/wiki/Per%20Enflo | Per H. Enflo (; born 20 May 1944) is a Swedish mathematician working primarily in functional analysis, a field in which he solved problems that had been considered fundamental. Three of these problems had been open for more than forty years:
The basis problem and the approximation problem and later
the invariant subspace problem for Banach spaces.
In solving these problems, Enflo developed new techniques which were then used by other researchers in functional analysis and operator theory for years. Some of Enflo's research has been important also in other mathematical fields, such as number theory, and in computer science, especially computer algebra and approximation algorithms.
Enflo works at Kent State University, where he holds the title of University Professor. Enflo has earlier held positions at the Miller Institute for Basic Research in Science at the University of California, Berkeley, Stanford University, École Polytechnique, (Paris) and The Royal Institute of Technology, Stockholm.
Enflo is also a concert pianist.
Enflo's contributions to functional analysis and operator theory
In mathematics, Functional analysis is concerned with the study of vector spaces and operators acting upon them. It has its historical roots in the study of functional spaces, in particular transformations of functions, such as the Fourier transform, as well as in the study of differential and integral equations. In functional analysis, an important class of vector spaces consists of the complete normed vector spaces over the real or complex numbers, which are called Banach spaces. An important example of a Banach space is a Hilbert space, where the norm arises from an inner product. Hilbert spaces are of fundamental importance in many areas, including the mathematical formulation of quantum mechanics, stochastic processes, and time-series analysis. Besides studying spaces of functions, functional analysis also studies the continuous linear operators on spaces of functions.
Hilbert's fifth problem and embeddings
At Stockholm University, Hans Rådström suggested that Enflo consider Hilbert's fifth problem in the spirit of functional analysis. In two years, 1969–1970, Enflo published five papers on Hilbert's fifth problem; these papers are collected in Enflo (1970), along with a short summary. Some of the results of these papers are described in Enflo (1976) and in the last chapter of Benyamini and Lindenstrauss.
Applications in computer science
Enflo's techniques have found application in computer science. Algorithm theorists derive approximation algorithms that embed finite metric spaces into low-dimensional Euclidean spaces with low "distortion" (in Gromov's terminology for the Lipschitz category; c.f. Banach–Mazur distance). Low-dimensional problems have lower computational complexity, of course. More importantly, if the problems embed well in either the Euclidean plane or the three-dimensional Euclidean space, then geometric algorithms become exceptionally fast.
However, such embedding techniques have limitations, as shown by Enflo's (1969) theorem:
For every , the Hamming cube cannot be embedded with "distortion " (or less) into -dimensional Euclidean space if . Consequently, the optimal embedding is the natural embedding, which realizes as a subspace of -dimensional Euclidean space.
This theorem, "found by Enflo [1969], is probably the first result showing an unbounded distortion for embeddings into Euclidean spaces. Enflo considered the problem of uniform embeddability among Banach spaces, and the distortion was an auxiliary device in his proof."
Geometry of Banach spaces
A uniformly convex space is a Banach space so that, for every there is some so that for any two vectors with and
implies that
Intuitively, the center of a line segment inside the unit ball must lie deep inside the unit ball unless the segment is short.
In 1972 Enflo proved that "every super-reflexive Banach space admits an equivalent uniformly convex norm".
The basis problem and Mazur's goose
With one paper, which was published in 1973, Per Enflo solved three problems that had stumped functional analysts for decades: The basis problem of Stefan Banach, the "Goose problem" of Stanisław Mazur, and the approximation problem of Alexander Grothendieck. Grothendieck had shown that his approximation problem was the central problem in the theory of Banach spaces and continuous linear operators.
Basis problem of Banach
The basis problem was posed by Stefan Banach in his book, Theory of Linear Operators. Banach asked whether every separable Banach space has a Schauder basis.
A Schauder basis or countable basis is similar to the usual (Hamel) basis of a vector space; the difference is that for Hamel bases we use linear combinations that are finite sums, while for Schauder bases they may be infinite sums. This makes Schauder bases more suitable for the analysis of infinite-dimensional topological vector spaces including Banach spaces.
Schauder bases were described by Juliusz Schauder in 1927. Let V denote a Banach space over the field F. A Schauder basis is a sequence (bn) of elements of V such that for every element v ∈ V there exists a unique sequence (αn) of elements in F so that
where the convergence is understood with respect to the norm topology. Schauder bases can also be defined analogously in a general topological vector space.
Problem 153 in the Scottish Book: Mazur's goose
Banach and other Polish mathematicians would work on mathematical problems at the Scottish Café. When a problem was especially interesting and when its solution seemed difficult, the problem would be written down in the book of problems, which soon became known as the Scottish Book. For problems that seemed especially important or difficult or both, the problem's proposer would often pledge to award a prize for its solution.
On 6 November 1936, Stanisław Mazur posed a problem on representing continuous functions. Formally writing down problem 153 in the Scottish Book, Mazur promised as the reward a "live goose", an especially rich price during the Great Depression and on the eve of World War II.
Fairly soon afterwards, it was realized that Mazur's problem was closely related to Banach's problem on the existence of Schauder bases in separable Banach spaces. Most of the other problems in the Scottish Book were solved regularly. However, there was little progress on Mazur's problem and a few other problems, which became famous open problems to mathematicians around the world.
Grothendieck's formulation of the approximation problem
Grothendieck's work on the theory of Banach spaces and continuous linear operators introduced the approximation property. A Banach space is said to have the approximation property, if every compact operator is a limit of finite-rank operators. The converse is always true.
In a long monograph, Grothendieck proved that if every Banach space had the approximation property, then every Banach space would have a Schauder basis. Grothendieck thus focused the attention of functional analysts on deciding whether every Banach space have the approximation property.
Enflo's solution
In 1972, Per Enflo constructed a separable Banach space that lacks the approximation property and a Schauder basis. In 1972, Mazur awarded a live goose to Enflo in a ceremony at the Stefan Banach Center in Warsaw; the "goose reward" ceremony was broadcast throughout Poland.
Invariant subspace problem and polynomials
In functional analysis, one of the most prominent problems was the invariant subspace problem, which required the evaluation of the truth of the following proposition:
Given a complex Banach space H of dimension > 1 and a bounded linear operator T : H → H, then H has a non-trivial closed T-invariant subspace, i.e. there exists a closed linear subspace W of H which is different from {0} and H such that T(W) ⊆ W.
For Banach spaces, the first example of an operator without an invariant subspace was constructed by Enflo. (For Hilbert spaces, the invariant subspace problem remains open.)
Enflo proposed a solution to the invariant subspace problem in 1975, publishing an outline in 1976. Enflo submitted the full article in 1981 and the article's complexity and length delayed its publication to 1987 Enflo's long "manuscript had a world-wide circulation among mathematicians" and some of its ideas were described in publications besides Enflo (1976). Enflo's works inspired a similar construction of an operator without an invariant subspace for example by Beauzamy, who acknowledged Enflo's ideas.
In the 1990s, Enflo developed a "constructive" approach to the invariant subspace problem on Hilbert spaces.
Multiplicative inequalities for homogeneous polynomials
An essential idea in Enflo's construction was "concentration of polynomials at low degrees": For all positive integers and , there exists such that for all homogeneous polynomials and of degrees and (in variables), then
where denotes the sum of the absolute values of the coefficients of . Enflo proved that does not depend on the number of variables . Enflo's original proof was simplified by Montgomery.
This result was generalized to other norms on the vector space of homogeneous polynomials. Of these norms, the most used has been the Bombieri norm.
Bombieri norm
The Bombieri norm is defined in terms of the following scalar product:
For all we have
if
For every we define
where we use the following notation:
if , we write and
and
The most remarkable property of this norm is the Bombieri inequality:
Let be two homogeneous polynomials respectively of degree and with variables, then, the following inequality holds:
In the above statement, the Bombieri inequality is the left-hand side inequality; the right-hand side inequality means that the Bombieri norm is a norm of the algebra of polynomials under multiplication.
The Bombieri inequality implies that the product of two polynomials cannot be arbitrarily small, and this lower-bound is fundamental in applications like polynomial factorization (or in Enflo's construction of an operator without an invariant subspace).
Applications
Enflo's idea of "concentration of polynomials at low degrees" has led to important publications in number theory algebraic and Diophantine geometry, and polynomial factorization.
Mathematical biology: Population dynamics
In applied mathematics, Per Enflo has published several papers in mathematical biology, specifically in population dynamics.
Human evolution
Enflo has also published in population genetics and paleoanthropology.
Today, all humans belong to one population of Homo sapiens sapiens, which is individed by species barrier. However, according to the "Out of Africa" model this is not the first species of hominids: the first species of genus Homo, Homo habilis, evolved in East Africa at least 2 Ma, and members of this species populated different parts of Africa in a relatively short time. Homo erectus evolved more than 1.8 Ma, and by 1.5 Ma had spread throughout the Old World.
Anthropologists have been divided as to whether current human population evolved as one interconnected population (as postulated by the Multiregional Evolution hypothesis), or evolved only in East Africa, speciated, and then migrating out of Africa and replaced human populations in Eurasia (called the "Out of Africa" Model or the "Complete Replacement" Model).
Neanderthals and modern humans coexisted in Europe for several thousand years, but the duration of this period is uncertain. Modern humans may have first migrated to Europe 40–43,000 years ago. Neanderthals may have lived as recently as 24,000 years ago in refugia on the south coast of the Iberian peninsula such as Gorham's Cave. Inter-stratification of Neanderthal and modern human remains has been suggested, but is disputed.
With Hawks and Wolpoff, Enflo published an explanation of fossil evidence on the DNA of Neanderthal and modern humans. This article tries to resolve a debate in the evolution of modern humans between theories suggesting either multiregional and single African origins. In particular,
the extinction of Neanderthals could have happened due to waves of modern humans entered Europe – in technical terms, due to "the continuous influx of modern human DNA into the Neandertal gene pool."
Enflo has also written about the population dynamics of zebra mussels in Lake Erie.
Piano
Per Enflo is also a concert pianist.
A child prodigy in both music and mathematics, Enflo won the Swedish competition for young pianists at age 11 in 1956, and he won the same competition in 1961. At age 12, Enflo appeared as a soloist with the Royal Opera Orchestra of Sweden. He debuted in the Stockholm Concert Hall in 1963. Enflo's teachers included Bruno Seidlhofer, Géza Anda, and Gottfried Boon (who himself was a student of Arthur Schnabel).
In 1999 Enflo competed in the first annual Van Cliburn Foundation's International Piano Competition for Outstanding Amateurs .
Enflo performs regularly around Kent and in a Mozart series in Columbus, Ohio (with the Triune Festival Orchestra). His solo piano recitals have appeared on the Classics Network of the radio station WOSU, which is sponsored by Ohio State University.
References
Notes
"Recipients of 2005 Distinguished Scholar Award at Kent State University Announced", eInside, 2005-4-11. Retrieved on February 4, 2007.
Bibliography
Enflo, Per. (1970) Investigations on Hilbert's fifth problem for non locally compact groups (Stockholm University). Enflo's thesis contains reprints of exactly five papers:
Enflo, Per. 1976. Uniform homeomorphisms between Banach spaces. Séminaire Maurey-Schwartz (1975—1976), Espaces, , applications radonifiantes et géométrie des espaces de Banach, Exp. No. 18, 7 pp. Centre Math., École Polytech., Palaiseau. (57 #17222) [Highlights of papers on Hilbert's fifth problem and on independent results of Martin Ribe, another student of Hans Rådström]
(accessible to readers with undergraduate mathematics)
P. Enflo, John D. Hawks, M. Wolpoff. "A simple reason why Neanderthal ancestry can be consistent with current DNA information". American Journal Physical Anthropology, 2001
Grothendieck, A.: Produits tensoriels topologiques et espaces nucleaires. Memo. Amer. Math. Soc. 16 (1955).
Paul R. Halmos, "Has progress in mathematics slowed down?" Amer. Math. Monthly 97 (1990), no. 7, 561–588.
William B. Johnson "Complementably universal separable Banach spaces" in Robert G. Bartle (ed.), 1980 Studies in functional analysis, Mathematical Association of America.
Kwapień, S. "On Enflo's example of a Banach space without the approximation property". Séminaire Goulaouic-Schwartz 1972—1973: Équations aux dérivées partielles et analyse fonctionnelle, Exp. No. 8, 9 pp. Centre de Math., École Polytech., Paris, 1973.
Lindenstrauss, Joram and Benyamini, Yoav. Geometric nonlinear functional analysis Colloquium publications, 48. American Mathematical Society.
Lindenstrauss, J.; Tzafriri, L.: Classical Banach Spaces I, Sequence spaces, 1977. Springer-Verlag.
.
Karen Saxe, Beginning Functional Analysis, Undergraduate Texts in Mathematics, 2002 Springer-Verlag, New York. (Pages 122–123 sketch a biography of Per Enflo.)
Schmidt, Wolfgang M. (1980 [1996 with minor corrections]) Diophantine approximation. Lecture Notes in Mathematics 785. Springer.
Singer, Ivan. Bases in Banach spaces. II. Editura Academiei Republicii Socialiste România, Bucharest; Springer-Verlag, Berlin-New York, 1981. viii+880 pp. .
External sources
Biography of Per Enflo at Canisius College
Homepage of Per Enflo at Kent State University
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20th-century American male musicians | Per Enflo | [
"Mathematics"
] | 3,452 | [
"Mathematical analysis",
"Number theorists",
"Mathematical analysts",
"Number theory"
] |
7,181,677 | https://en.wikipedia.org/wiki/AACE%20International | AACE International (Association for the Advancement of Cost Engineering) was founded in 1956 by 59 cost estimators and cost engineers during the organizational meeting of the American Association of Cost Engineering at the University of New Hampshire in Durham, New Hampshire. AACE International Headquarters is located in Morgantown, West Virginia, USA. AACE is a 501(c)(3) non-profit professional association. AACE International is a member of the Board of the Council of Engineering and Scientific Specialty Boards (CESB).
Activities
AACE is a non-profit organization with about 15 employees at its headquarters in Morgantown, WV. A variety of other organizations in the United States provide similar certifications, often specialized for particular industries, such as power, manufacturing, gas and oil.
AACE is the publisher of Cost Engineering, a bi-monthly technical journal, Skills and Knowledge of Cost Engineering (currently in its 6th edition), Source magazine (a bi-monthly magazine), 20 different AACE International Professional Practice Guides, approximately 120 Recommended Practices, and its most comprehensive publication, the Total Cost Management Framework: An Integrated Approach to Portfolio, Program and Project Management.
Certification programs
AACE currently manages eight certification programs, as listed below. All require agreeing to adhere to canons of ethics, and passing an examination. Most require prior industry experience, and also involve recertification by continuing education or reexamination.
Certified Cost Technician (formerly known as Interim Cost Consultant), an entry-level certification and is not eligible for renewal
Certified Scheduling Technician, an entry-level certification
Certified Cost Professional (formerly Certified Cost Consultant / Certified Cost Engineer), which additionally requires a technical paper submission
Certified Estimating Professional
Certified Forensic Claims Consultant, which has additional requirements, including submission of a publication
Decision & Risk Management Professional
Earned Value Professional
Planning & Scheduling Professional
Since becoming a charter member of the Council of Engineering and Scientific Specialty Boards in 1990, six of its certification programs (CCP, CCT, CEP, CST, EVP and PSP) have been accredited by the CESB.
Membership
As of 2012, AACE reported over 8,000 members. To network in local areas, there are over 80 local sections located in 80 countries. There are also 11 technical subcommittees and 17 special interest groups.
References
Further reading
"Total Cost Management Framework: An Integrated Approach to Portfolio, Program and Project Management," 2nd Edition, AACE International, Morgantown, West Virginia, 2016
"Skills and Knowledge of Cost Engineering," 6th Edition, AACE International, Morgantown, West Virginia, 2016.
External links
AACE International
What is cost engineering? - a white paper
The Total Cost Management Framework; An Integrate Approach to Portfolio, Program and Project Management
Professional associations based in the United States
Cost engineering
Engineering societies based in the United States | AACE International | [
"Engineering"
] | 567 | [
"Cost engineering"
] |
7,181,855 | https://en.wikipedia.org/wiki/Borel%20conjecture | In geometric topology, the Borel conjecture (named for Armand Borel) asserts that an aspherical closed manifold is determined by its fundamental group, up to homeomorphism. It is a rigidity conjecture, asserting that a weak, algebraic notion of equivalence (namely, homotopy equivalence) should imply a stronger, topological notion (namely, homeomorphism).
Precise formulation of the conjecture
Let and be closed and aspherical topological manifolds, and let
be a homotopy equivalence. The Borel conjecture states that the map is homotopic to a homeomorphism. Since aspherical manifolds with isomorphic fundamental groups are homotopy equivalent, the Borel conjecture implies that aspherical closed manifolds are determined, up to homeomorphism, by their fundamental groups.
This conjecture is false if topological manifolds and homeomorphisms are replaced by smooth manifolds and diffeomorphisms; counterexamples can be constructed by taking a connected sum with an exotic sphere.
The origin of the conjecture
In a May 1953 letter to Jean-Pierre Serre, Armand Borel raised the question whether two aspherical manifolds with isomorphic fundamental groups are homeomorphic. A positive answer to the question "Is every homotopy equivalence between closed aspherical manifolds homotopic to a homeomorphism?" is referred to as the "so-called Borel Conjecture" in a 1986 paper of Jonathan Rosenberg.
Motivation for the conjecture
A basic question is the following: if two closed manifolds are homotopy equivalent, are they homeomorphic? This is not true in general: there are homotopy equivalent lens spaces which are not homeomorphic.
Nevertheless, there are classes of manifolds for which homotopy equivalences between them can be homotoped to homeomorphisms. For instance, the Mostow rigidity theorem states that a homotopy equivalence between closed hyperbolic manifolds is homotopic to an isometry—in particular, to a homeomorphism. The Borel conjecture is a topological reformulation of Mostow rigidity, weakening the hypothesis from hyperbolic manifolds to aspherical manifolds, and similarly weakening the conclusion from an isometry to a homeomorphism.
Relationship to other conjectures
The Borel conjecture implies the Novikov conjecture for the special case in which the reference map is a homotopy equivalence.
The Poincaré conjecture asserts that a closed manifold homotopy equivalent to , the 3-sphere, is homeomorphic to . This is not a special case of the Borel conjecture, because is not aspherical. Nevertheless, the Borel conjecture for the 3-torus implies the Poincaré conjecture for .
References
Further reading
Matthias Kreck, and Wolfgang Lück, The Novikov conjecture. Geometry and algebra. Oberwolfach Seminars, 33. Birkhäuser Verlag, Basel, 2005.
Geometric topology
Homeomorphisms
Conjectures
Unsolved problems in geometry
Surgery theory | Borel conjecture | [
"Mathematics"
] | 620 | [
"Geometry problems",
"Unsolved problems in mathematics",
"Homeomorphisms",
"Unsolved problems in geometry",
"Geometric topology",
"Conjectures",
"Topology",
"Mathematical problems"
] |
7,181,923 | https://en.wikipedia.org/wiki/Space-filling%20model | In chemistry, a space-filling model, also known as a calotte model, is a type of three-dimensional (3D) molecular model where the atoms are represented by spheres whose radii are proportional to the radii of the atoms and whose center-to-center distances are proportional to the distances between the atomic nuclei, all in the same scale. Atoms of different chemical elements are usually represented by spheres of different colors.
Space-filling calotte models are also referred to as CPK models after the chemists Robert Corey, Linus Pauling, and Walter Koltun, who over a span of time developed the modeling concept into a useful form. They are distinguished from other 3D representations, such as the ball-and-stick and skeletal models, by the use of the "full size" space-filling spheres for the atoms. The models are tactile and manually rotatable. They are useful for visualizing the effective shape and relative dimensions of a molecule, and (because of the rotatability) the shapes of the surface of the various conformers. On the other hand, these models mask the chemical bonds between the atoms, and make it difficult to see the structure of the molecule that is obscured by the atoms nearest to the viewer in a particular pose. For this reason, such models are of greater utility if they can be used dynamically, especially when used with complex molecules (e.g., see the greater understanding of the molecules shape given when the THC model is clicked on to rotate).
History
Space-filling models arise out of a desire to represent molecules in ways that reflect the electronic surfaces that molecules present, that dictate how they interact, one with another (or with surfaces, or macromolecules such as enzymes, etc.). Crystallographic data are the starting point for understanding static molecular structure, and these data contain the information rigorously required to generate space-filling representations (e.g., see these crystallographic models); most often, however, crystallographers present the locations of atoms derived from crystallography via "thermal ellipsoids" whose cut-off parameters are set for convenience both to show the atom locations (with anisotropies), and to allow representation of the covalent bonds or other interactions between atoms as lines. In short, for reasons of utility, crystallographic data historically have appeared in presentations closer to ball-and-stick models. Hence, while crystallographic data contain the information to create space-filling models, it remained for individuals interested in modeling an effective static shape of a molecule, and the space it occupied, and the ways in which it might present a surface to another molecule, to develop the formalism shown above.
In 1952, Robert Corey and Linus Pauling described accurate scale models of molecules which they had built at Caltech. In their models, they envisioned the surface of the molecule as being determined by the van der Waals radius of each atom of the molecule, and crafted atoms as hardwood spheres of diameter proportional to each atom's van der Waals radius, in the scale 1 inch = 1 Å. To allow bonds between atoms a portion of each sphere was cut away to create a pair of matching flat faces, with the cuts dimensioned so that the distance between sphere centers was proportional to the lengths of standard types of chemical bonds. A connector was designed—a metal bushing that threaded into each sphere at the center of each flat face. The two spheres were then firmly held together by a metal rod inserted into the pair of opposing bushing (with fastening by screws). The models also had special features to allow representation of hydrogen bonds.
In 1965, Walter L. Koltun designed and patented a simplified system with molded plastic atoms of various colours, which were joined by specially designed snap connectors; this simpler system accomplished essentially the same ends as the Corey-Pauling system, and allowed for the development of the models as a popular way of working with molecules in training and research environments. Such colour-coded, bond length-defined, van der Waals-type space-filling models are now commonly known as CPK models, after these three developers of the specific concept.
In modern research efforts, attention returned to use of data-rich crystallographic models in combination with traditional and new computational methods to provide space-filling models of molecules, both simple and complex, where added information such as which portions of the surface of the molecule were readily accessible to solvent, or how the electrostatic characteristics of a space-filling representation—which in the CPK case is almost fully left to the imagination—could be added to the visual models created. The two closing images give examples of the latter type of calculation and representation, and its utility.
See also
Ball-and-stick model
Van der Waals surface
CPK coloring
Molecular graphics
Software for molecular modeling
Molecular design software
References
External links
More on molecular models and a couple of examples from chemistry and biology (article is in German)
Gallery
Molecular modelling
Surfaces | Space-filling model | [
"Chemistry"
] | 1,027 | [
"Theoretical chemistry",
"Molecular modelling",
"Molecular physics"
] |
581,859 | https://en.wikipedia.org/wiki/Invertible%20sheaf | In mathematics, an invertible sheaf is a sheaf on a ringed space that has an inverse with respect to tensor product of sheaves of modules. It is the equivalent in algebraic geometry of the topological notion of a line bundle. Due to their interactions with Cartier divisors, they play a central role in the study of algebraic varieties.
Definition
Let (X, OX) be a ringed space. Isomorphism classes of sheaves of OX-modules form a monoid under the operation of tensor product of OX-modules. The identity element for this operation is OX itself. Invertible sheaves are the invertible elements of this monoid. Specifically, if L is a sheaf of OX-modules, then L is called invertible if it satisfies any of the following equivalent conditions:
There exists a sheaf M such that .
The natural homomorphism is an isomorphism, where denotes the dual sheaf .
The functor from OX-modules to OX-modules defined by is an equivalence of categories.
Every locally free sheaf of rank one is invertible. If X is a locally ringed space, then L is invertible if and only if it is locally free of rank one. Because of this fact, invertible sheaves are closely related to line bundles, to the point where the two are sometimes conflated.
Examples
Let X be an affine scheme . Then an invertible sheaf on X is the sheaf associated to a rank one projective module over R. For example, this includes fractional ideals of algebraic number fields, since these are rank one projective modules over the rings of integers of the number field.
The Picard group
Quite generally, the isomorphism classes of invertible sheaves on X themselves form an abelian group under tensor product. This group generalises the ideal class group. In general it is written
with Pic the Picard functor. Since it also includes the theory of the Jacobian variety of an algebraic curve, the study of this functor is a major issue in algebraic geometry.
The direct construction of invertible sheaves by means of data on X leads to the concept of Cartier divisor.
See also
Vector bundles in algebraic geometry
Line bundle
First Chern class
Picard group
Birkhoff-Grothendieck theorem
References
Geometry of divisors
Sheaf theory | Invertible sheaf | [
"Mathematics"
] | 487 | [
"Topology",
"Sheaf theory",
"Mathematical structures",
"Category theory"
] |
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