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27,543,580 | https://en.wikipedia.org/wiki/Bruce%20effect | The Bruce effect, or pregnancy block, is the tendency for female rodents to terminate their pregnancies following exposure to the scent of an unfamiliar male. The effect was first noted in 1959 by Hilda M. Bruce, and has primarily been studied in laboratory mice (Mus musculus). In mice, pregnancy can only be terminated prior to embryo implantation, but other species will interrupt even a late-term pregnancy.
The Bruce effect is also observed in deer-mice, meadow voles, collared lemmings, and it has also been proposed, but not confirmed, in other non-rodent species such as lions and geladas.
Discovery
In an experiment published in 1959, zoologist Hilda Bruce of the National Institute for Medical Research in London housed pregnant mice with male mice that were not the father of the carried embryo. As a result, the rate of miscarriages increased, followed by mating with the new male. No increased rate of miscarriages occurred when pregnant mice were paired with castrated or juvenile male mice. The effect remained when the male mice were kept out of sight or hearing of the females. This suggested that females were distinguishing the males by smell. To test this hypothesis, Bruce and her colleague Alan Parkes recruited perfumers to smell pieces of cloth from the mouse cages. The perfumers could distinguish the smells of different mouse strains.
Mechanisms of action
Detection of pheromones
The vomeronasal system serves as a "vascular pump" that, stimulated by the presence of a novel male, actively draws in substances. Male mouse urine contains MHC class I peptides that bind to receptors in the female's vomeronasal organ, a mucus-filled structure in the nasal septum. These chemical signals, which are specific to each male, are learned by the female during mating, or shortly after. The hormone vasopressin is crucial in coupling a chemosensory cue with an appropriate physiological response. When the vasopressin 1b receptor gene is knocked out in females, the presence of an unfamiliar male does not trigger pregnancy disruption.
Recognizing familiar males
Exposure to a male's urinal pheromones will activate a neuroendocrine pathway leading to pregnancy failure. However, if the pheromones correspond with those memorized by the female (usually the male mating partner), a release of noradrenaline will lower the receptivity of the accessory olfactory bulb to these pheromones. The pregnancy disruption will, thus, be averted. This role for noradrenaline has recently been called into question. The hormone oxytocin is also important in this social memory process. Females treated with an oxytocin antagonist are unable to recognize the urinary scent of their mate, and will terminate pregnancy when exposed to any male, known or unknown.
Neuroendocrine pathway
The activation of vomeronasal neuron receptors by male pheromones triggers a complex neuroendocrine pathway. The pheromonal information travels via nerves to the accessory olfactory bulb, and then to the corticomedial amygdala, accessory olfactory tract, and stria terminalis. These areas stimulate the hypothalamus to increase the release of dopamine, which thus prevents the secretion of prolactin from the anterior pituitary. In the absence of prolactin, an essential hormone for maintaining the corpus luteum, luteolysis takes place. As the corpus luteum can no longer release progesterone, the uterus remains unprimed for embryo implantation, and the pregnancy fails.
Role of estrogens
Androgens and estrogens, particularly estradiol (E2), are also crucial chemosignals regulating the Bruce effect. However, they are believed to act via a separate pathway to that discussed above. Small steroid molecules such as E2 can enter the bloodstream directly via nasal ingestion and travel to the uterus, which has a high density of suitable receptors. Normally, E2 is essential in preparing both the blastocyst and uterus for implantation. However, excessive E2 will prevent implantation from taking place. Castrated males are incapable of terminating female pregnancies, except when castrated males are given testosterone. estradiol, a metabolic product of testosterone, is known to disrupt pregnancy in females, and is present in male urine.
Timing
The incidence of the Bruce effect depends on the timing of pheromone exposure. Post-mating, females experience twice-daily surges of prolactin. Pregnancy is only terminated if exposure to novel male scent coincides with two prolactin surges, one of these occurring in a daylight period.
Evolutionary benefits
In order to have evolved and persisted in the population, the Bruce effect must afford individuals a fitness advantage. The possible advantages of pregnancy block are widely debated.
Males
When given the opportunity, male mice tend to direct their urine in the female's direction. This allows males to improve their fitness success by "sabotaging" the pregnancy of a male competitor, and more quickly returning the female to estrus. The Bruce effect can also aid in maintaining social status, with dominant males leaving more urinal scent markings, and so blocking the pregnancies initiated by subordinate males.
Females
Females can control their likelihood of terminating pregnancy by pursuing or avoiding novel male contact during their most susceptible periods. In this way, females can exert a post-copulatory mate choice, reserving their reproductive resources for the highest-quality male. Certainly, females are more likely to seek proximity to dominant males. In many rodent species, males kill unrelated young; pregnancy block may avoid the wasted investment of gestating offspring likely to be killed at birth. The Bruce effect is most common in polygynous rodent species, for which the risk of infanticide is highest.
See also
Coolidge effect
Lee–Boot effect
Vandenbergh effect
Whitten effect
References
Further reading
Ethology
Reproduction in mammals
Rodents | Bruce effect | Biology | 1,241 |
664,488 | https://en.wikipedia.org/wiki/Reciprocal%20lattice | The reciprocal lattice is a term associated with solids with translational symmetry, and plays a major role in many areas such as X-ray and electron diffraction as well as the energies of electrons in a solid. It emerges from the Fourier transform of the lattice associated with the arrangement of the atoms. The direct lattice or real lattice is a periodic function in physical space, such as a crystal system (usually a Bravais lattice). The reciprocal lattice exists in the mathematical space of spatial frequencies, known as reciprocal space or k space, which is the dual of physical space considered as a vector space, and the reciprocal lattice is the sublattice of that space that is dual to the direct lattice.
In quantum physics, reciprocal space is closely related to momentum space according to the proportionality , where is the momentum vector and is the reduced Planck constant. The reciprocal lattice of a reciprocal lattice is equivalent to the original direct lattice, because the defining equations are symmetrical with respect to the vectors in real and reciprocal space. Mathematically, direct and reciprocal lattice vectors represent covariant and contravariant vectors, respectively.
The reciprocal lattice is the set of all vectors , that are wavevectors of plane waves in the Fourier series of a spatial function whose periodicity is the same as that of a direct lattice . Each plane wave in this Fourier series has the same phase or phases that are differed by multiples of at each direct lattice point (so essentially same phase at all the direct lattice points).
The Brillouin zone is a Wigner–Seitz cell of the reciprocal lattice.
Wave-based description
Reciprocal space
Reciprocal space (also called -space) provides a way to visualize the results of the Fourier transform of a spatial function. It is similar in role to the frequency domain arising from the Fourier transform of a time dependent function; reciprocal space is a space over which the Fourier transform of a spatial function is represented at spatial frequencies or wavevectors of plane waves of the Fourier transform. The domain of the spatial function itself is often referred to as real space. In physical applications, such as crystallography, both real and reciprocal space will often each be two or three dimensional. Whereas the number of spatial dimensions of these two associated spaces will be the same, the spaces will differ in their quantity dimension, so that when the real space has the dimension length (L), its reciprocal space will have inverse length, so L−1 (the reciprocal of length).
Reciprocal space comes into play regarding waves, both classical and quantum mechanical. Because a sinusoidal plane wave with unit amplitude can be written as an oscillatory term , with initial phase , angular wavenumber and angular frequency , it can be regarded as a function of both and (and the time-varying part as a function of both and ). This complementary role of and leads to their visualization within complementary spaces (the real space and the reciprocal space). The spatial periodicity of this wave is defined by its wavelength , where ; hence the corresponding wavenumber in reciprocal space will be .
In three dimensions, the corresponding plane wave term becomes , which simplifies to at a fixed time , where is the position vector of a point in real space and now is the wavevector in the three dimensional reciprocal space. (The magnitude of a wavevector is called wavenumber.) The constant is the phase of the wavefront (a plane of a constant phase) through the origin at time , and is a unit vector perpendicular to this wavefront. The wavefronts with phases , where represents any integer, comprise a set of parallel planes, equally spaced by the wavelength .
Reciprocal lattice
In general, a geometric lattice is an infinite, regular array of vertices (points) in space, which can be modelled vectorially as a Bravais lattice. Some lattices may be skew, which means that their primary lines may not necessarily be at right angles. In reciprocal space, a reciprocal lattice is defined as the set of wavevectors of plane waves in the Fourier series of any function whose periodicity is compatible with that of an initial direct lattice in real space. Equivalently, a wavevector is a vertex of the reciprocal lattice if it corresponds to a plane wave in real space whose phase at any given time is the same (actually differs by with an integer ) at every direct lattice vertex.
One heuristic approach to constructing the reciprocal lattice in three dimensions is to write the position vector of a vertex of the direct lattice as , where the are integers defining the vertex and the are linearly independent primitive translation vectors (or shortly called primitive vectors) that are characteristic of the lattice. There is then a unique plane wave (up to a factor of negative one), whose wavefront through the origin contains the direct lattice points at and , and with its adjacent wavefront (whose phase differs by or from the former wavefront passing the origin) passing through . Its angular wavevector takes the form , where is the unit vector perpendicular to these two adjacent wavefronts and the wavelength must satisfy , means that is equal to the distance between the two wavefronts. Hence by construction and .
Cycling through the indices in turn, the same method yields three wavevectors with , where the Kronecker delta equals one when and is zero otherwise. The comprise a set of three primitive wavevectors or three primitive translation vectors for the reciprocal lattice, each of whose vertices takes the form , where the are integers. The reciprocal lattice is also a Bravais lattice as it is formed by integer combinations of the primitive vectors, that are , , and in this case. Simple algebra then shows that, for any plane wave with a wavevector on the reciprocal lattice, the total phase shift between the origin and any point on the direct lattice is a multiple of (that can be possibly zero if the multiplier is zero), so the phase of the plane wave with will essentially be equal for every direct lattice vertex, in conformity with the reciprocal lattice definition above. (Although any wavevector on the reciprocal lattice does always take this form, this derivation is motivational, rather than rigorous, because it has omitted the proof that no other possibilities exist.)
The Brillouin zone is a primitive cell (more specifically a Wigner–Seitz cell) of the reciprocal lattice, which plays an important role in solid state physics due to Bloch's theorem. In pure mathematics, the dual space of linear forms and the dual lattice provide more abstract generalizations of reciprocal space and the reciprocal lattice.
Mathematical description
Assuming a three-dimensional Bravais lattice and labelling each lattice vector (a vector indicating a lattice point) by the subscript as 3-tuple of integers,
where
where is the set of integers and is a primitive translation vector or shortly primitive vector. Taking a function where is a position vector from the origin to any position, if follows the periodicity of this lattice, e.g. the function describing the electronic density in an atomic crystal, it is useful to write as a multi-dimensional Fourier series
where now the subscript , so this is a triple sum.
As follows the periodicity of the lattice, translating by any lattice vector we get the same value, hence
Expressing the above instead in terms of their Fourier series we have
Because equality of two Fourier series implies equality of their coefficients, , which only holds when
where
Mathematically, the reciprocal lattice is the set of all vectors , that are wavevectors of plane waves in the Fourier series of a spatial function whose periodicity is the same as that of a direct lattice as the set of all direct lattice point position vectors , and satisfy this equality for all . Each plane wave in the Fourier series has the same phase (actually can be differed by a multiple of ) at all the lattice point .
As shown in the section multi-dimensional Fourier series, can be chosen in the form of where . With this form, the reciprocal lattice as the set of all wavevectors for the Fourier series of a spatial function which periodicity follows , is itself a Bravais lattice as it is formed by integer combinations of its own primitive translation vectors , and the reciprocal of the reciprocal lattice is the original lattice, which reveals the Pontryagin duality of their respective vector spaces. (There may be other form of . Any valid form of results in the same reciprocal lattice.)
Two dimensions
For an infinite two-dimensional lattice, defined by its primitive vectors , its reciprocal lattice can be determined by generating its two reciprocal primitive vectors, through the following formulae,
where is an integer and
Here represents a 90 degree rotation matrix, i.e. a quarter turn. The anti-clockwise rotation and the clockwise rotation can both be used to determine the reciprocal lattice: If is the anti-clockwise rotation and is the clockwise rotation, for all vectors . Thus, using the permutation
we obtain
Notably, in a 3D space this 2D reciprocal lattice is an infinitely extended set of Bragg rods—described by Sung et al.
Three dimensions
For an infinite three-dimensional lattice , defined by its primitive vectors and the subscript of integers , its reciprocal lattice with the integer subscript can be determined by generating its three reciprocal primitive vectors
where is the scalar triple product. The choice of these is to satisfy as the known condition (There may be other condition.) of primitive translation vectors for the reciprocal lattice derived in the heuristic approach above and the section multi-dimensional Fourier series. This choice also satisfies the requirement of the reciprocal lattice mathematically derived above. Using column vector representation of (reciprocal) primitive vectors, the formulae above can be rewritten using matrix inversion:
This method appeals to the definition, and allows generalization to arbitrary dimensions. The cross product formula dominates introductory materials on crystallography.
The above definition is called the "physics" definition, as the factor of comes naturally from the study of periodic structures. An essentially equivalent definition, the "crystallographer's" definition, comes from defining the reciprocal lattice . which changes the reciprocal primitive vectors to be
and so on for the other primitive vectors. The crystallographer's definition has the advantage that the definition of is just the reciprocal magnitude of in the direction of , dropping the factor of . This can simplify certain mathematical manipulations, and expresses reciprocal lattice dimensions in units of spatial frequency. It is a matter of taste which definition of the lattice is used, as long as the two are not mixed.
is conventionally written as or , called Miller indices; is replaced with , replaced with , and replaced with . Each lattice point in the reciprocal lattice corresponds to a set of lattice planes in the real space lattice. (A lattice plane is a plane crossing lattice points.) The direction of the reciprocal lattice vector corresponds to the normal to the real space planes. The magnitude of the reciprocal lattice vector is given in reciprocal length and is equal to the reciprocal of the interplanar spacing of the real space planes.
Higher dimensions
The formula for dimensions can be derived assuming an -dimensional real vector space with a basis and an inner product . The reciprocal lattice vectors are uniquely determined by the formula . Using the permutation
they can be determined with the following formula:
Here, is the volume form, is the inverse of the vector space isomorphism defined by and denotes the inner multiplication.
One can verify that this formula is equivalent to the known formulas for the two- and three-dimensional case by using the following facts: In three dimensions, and in two dimensions, , where is the rotation by 90 degrees (just like the volume form, the angle assigned to a rotation depends on the choice of orientation).
Reciprocal lattices of various crystals
Reciprocal lattices for the cubic crystal system are as follows.
Simple cubic lattice
The simple cubic Bravais lattice, with cubic primitive cell of side , has for its reciprocal a simple cubic lattice with a cubic primitive cell of side (or in the crystallographer's definition). The cubic lattice is therefore said to be self-dual, having the same symmetry in reciprocal space as in real space.
Face-centered cubic (FCC) lattice
The reciprocal lattice to an FCC lattice is the body-centered cubic (BCC) lattice, with a cube side of .
Consider an FCC compound unit cell. Locate a primitive unit cell of the FCC; i.e., a unit cell with one lattice point. Now take one of the vertices of the primitive unit cell as the origin. Give the basis vectors of the real lattice. Then from the known formulae, you can calculate the basis vectors of the reciprocal lattice. These reciprocal lattice vectors of the FCC represent the basis vectors of a BCC real lattice. The basis vectors of a real BCC lattice and the reciprocal lattice of an FCC resemble each other in direction but not in magnitude.
Body-centered cubic (BCC) lattice
The reciprocal lattice to a BCC lattice is the FCC lattice, with a cube side of .
It can be proven that only the Bravais lattices which have 90 degrees between (cubic, tetragonal, orthorhombic) have primitive translation vectors for the reciprocal lattice, , parallel to their real-space vectors.
Simple hexagonal lattice
The reciprocal to a simple hexagonal Bravais lattice with lattice constants and is another simple hexagonal lattice with lattice constants and rotated through 90° about the c axis with respect to the direct lattice. The simple hexagonal lattice is therefore said to be self-dual, having the same symmetry in reciprocal space as in real space. Primitive translation vectors for this simple hexagonal Bravais lattice vectors are
Arbitrary collection of atoms
One path to the reciprocal lattice of an arbitrary collection of atoms comes from the idea of scattered waves in the Fraunhofer (long-distance or lens back-focal-plane) limit as a Huygens-style sum of amplitudes from all points of scattering (in this case from each individual atom). This sum is denoted by the complex amplitude in the equation below, because it is also the Fourier transform (as a function of spatial frequency or reciprocal distance) of an effective scattering potential in direct space:
Here g = q/(2) is the scattering vector q in crystallographer units, N is the number of atoms, fj[g] is the atomic scattering factor for atom j and scattering vector g, while rj is the vector position of atom j. The Fourier phase depends on one's choice of coordinate origin.
For the special case of an infinite periodic crystal, the scattered amplitude F = M Fh,k,ℓ from M unit cells (as in the cases above) turns out to be non-zero only for integer values of , where
when there are j = 1,m atoms inside the unit cell whose fractional lattice indices are respectively {uj, vj, wj}. To consider effects due to finite crystal size, of course, a shape convolution for each point or the equation above for a finite lattice must be used instead.
Whether the array of atoms is finite or infinite, one can also imagine an "intensity reciprocal lattice" I[g], which relates to the amplitude lattice F via the usual relation I = F*F where F* is the complex conjugate of F. Since Fourier transformation is reversible, of course, this act of conversion to intensity tosses out "all except 2nd moment" (i.e. the phase) information. For the case of an arbitrary collection of atoms, the intensity reciprocal lattice is therefore:
Here rjk is the vector separation between atom j and atom k. One can also use this to predict the effect of nano-crystallite shape, and subtle changes in beam orientation, on detected diffraction peaks even if in some directions the cluster is only one atom thick. On the down side, scattering calculations using the reciprocal lattice basically consider an incident plane wave. Thus after a first look at reciprocal lattice (kinematic scattering) effects, beam broadening and multiple scattering (i.e. dynamical) effects may be important to consider as well.
Generalization of a dual lattice
There are actually two versions in mathematics of the abstract dual lattice concept, for a given lattice L in a real vector space V, of finite dimension.
The first, which generalises directly the reciprocal lattice construction, uses Fourier analysis. It may be stated simply in terms of Pontryagin duality. The dual group V^ to V is again a real vector space, and its closed subgroup L^ dual to L turns out to be a lattice in V^. Therefore, L^ is the natural candidate for dual lattice, in a different vector space (of the same dimension).
The other aspect is seen in the presence of a quadratic form Q on V; if it is non-degenerate it allows an identification of the dual space V* of V with V. The relation of V* to V is not intrinsic; it depends on a choice of Haar measure (volume element) on V. But given an identification of the two, which is in any case well-defined up to a scalar, the presence of Q allows one to speak to the dual lattice to L while staying within V.
In mathematics, the dual lattice of a given lattice L in an abelian locally compact topological group G is the subgroup L∗ of the dual group of G consisting of all continuous characters that are equal to one at each point of L.
In discrete mathematics, a lattice is a locally discrete set of points described by all integral linear combinations of linearly independent vectors in Rn. The dual lattice is then defined by all points in the linear span of the original lattice (typically all of Rn) with the property that an integer results from the inner product with all elements of the original lattice. It follows that the dual of the dual lattice is the original lattice.
Furthermore, if we allow the matrix B to have columns as the linearly independent vectors that describe the lattice, then the matrix has columns of vectors that describe the dual lattice.
See also
References
External links
http://newton.umsl.edu/run//nano/known.html – Jmol-based electron diffraction simulator lets you explore the intersection between reciprocal lattice and Ewald sphere during tilt.
DoITPoMS Teaching and Learning Package on Reciprocal Space and the Reciprocal Lattice
Learn easily crystallography and how the reciprocal lattice explains the diffraction phenomenon, as shown in chapters 4 and 5
Crystallography
Fourier analysis
Lattice points
Neutron-related techniques
Synchrotron-related techniques
Diffraction
Condensed matter physics | Reciprocal lattice | Physics,Chemistry,Materials_science,Mathematics,Engineering | 3,789 |
830,776 | https://en.wikipedia.org/wiki/Discrete%20valuation | In mathematics, a discrete valuation is an integer valuation on a field K; that is, a function:
satisfying the conditions:
for all .
Note that often the trivial valuation which takes on only the values is explicitly excluded.
A field with a non-trivial discrete valuation is called a discrete valuation field.
Discrete valuation rings and valuations on fields
To every field with discrete valuation we can associate the subring
of , which is a discrete valuation ring. Conversely, the valuation on a discrete valuation ring can be extended in a unique way to a discrete valuation on the quotient field ; the associated discrete valuation ring is just .
Examples
For a fixed prime and for any element different from zero write with such that does not divide . Then is a discrete valuation on , called the p-adic valuation.
Given a Riemann surface , we can consider the field of meromorphic functions . For a fixed point , we define a discrete valuation on as follows: if and only if is the largest integer such that the function can be extended to a holomorphic function at . This means: if then has a root of order at the point ; if then has a pole of order at . In a similar manner, one also defines a discrete valuation on the function field of an algebraic curve for every regular point on the curve.
More examples can be found in the article on discrete valuation rings.
Citations
References
Commutative algebra
Field (mathematics) | Discrete valuation | Mathematics | 288 |
2,625,993 | https://en.wikipedia.org/wiki/Erd%C5%91s%E2%80%93Bacon%20number | A person's Erdős–Bacon number is the sum of one's Erdős number—which measures the "collaborative distance" in authoring academic papers between that person and Hungarian mathematician Paul Erdős—and one's Bacon number—which represents the number of links, through roles in films, by which the person is separated from American actor Kevin Bacon. The lower the number, the closer a person is to Erdős and Bacon, which reflects a small world phenomenon in academia and entertainment.
To have a defined Erdős–Bacon number, it is necessary to have both appeared in a film and co-authored an academic paper, although this in and of itself is not sufficient as one's co-authors must have a known chain leading to Paul Erdős, and one's film must have actors eventually leading to Kevin Bacon.
Academic scientists
Albert-Laszlo Barabási has an Erdős–Bacon number 3, as he co-authored work with Laszlo Lovasz in Nature Physics, who has Erdős number 1, as he coauthored multiple papers with Erdős. Barabási has Bacon number of 1 via the documentary Connected, released in 2008.
Daniel Kleitman has an Erdős–Bacon number of 3. He co-authored papers with Erdős and has a Bacon number of 2 via Minnie Driver in Good Will Hunting; Driver and Bacon appeared together in Sleepers.
Like Kleitman, mathematician Bruce Reznick has co-authored a paper with Erdős and has a Bacon number of 2, via Roddy McDowall in the film Pretty Maids All in a Row where he appeared as an extra, giving him an Erdős–Bacon number of 3 as well.
Belgian economist François Maniquet has an Erdős number of 4, and also a Bacon number of 3 via the 2017 French film An Indian Tale, so that his Erdős–Bacon number is 7.
Physicist Nicholas Metropolis has an Erdős number of 2, and also a Bacon number of 2 via the Woody Allen film Husbands and Wives, giving him an Erdős–Bacon number of 4.
Metropolis and Richard Feynman both worked on the Manhattan Project at Los Alamos Laboratory. Via Metropolis, Feynman has an Erdős number of 3 and, from having appeared in the film Anti-Clock alongside Tony Tang, Feynman also has a Bacon number of 3. Richard Feynman thus has an Erdős–Bacon number of 6.
Theoretical physicist Stephen Hawking has an Erdős–Bacon number of 6: his Bacon number of 2 (via his appearance alongside John Cleese in Monty Python Live (Mostly), who acted alongside Kevin Bacon in The Big Picture) is lower than his Erdős number of 4.
Similarly to Stephen Hawking, scientist Carl Sagan has an Erdős–Bacon number of 6, also from a Bacon number of 2 and an Erdős number of 4.
Mathematician Jordan Ellenberg has an Erdős number of 3 and a Bacon number of 2 due to a cameo appearance in the film Gifted for which he was also the mathematical consultant.
Linguist Noam Chomsky has an Erdős number of 4, he also co-starred with Danny Glover in the 2005 documentary The Peace!, giving him a Bacon number of 2 and combined Erdős–Bacon number of 6.
Actors
Danica McKellar, who played Winnie Cooper in The Wonder Years, has an Erdős–Bacon number of 6. While an undergraduate at the University of California, Los Angeles, McKellar coauthored a mathematics paper with Lincoln Chayes, who via his wife Jennifer Tour Chayes has an Erdős number of 3, giving McKellar one of 4. Having worked with Margaret Easley, McKellar has a Bacon number of 2.
Israeli-American actress Natalie Portman has an Erdős–Bacon number of 7. She collaborated (using her birth name, Natalie Hershlag) with Abigail A. Baird, who has a collaboration path leading to Joseph Gillis, who has an Erdős number of 1, giving Portman an Erdős number of 5. Portman appeared in A Powerful Noise Live (2009) with Sarah Michelle Gellar, who appeared in The Air I Breathe (2007) with Bacon, giving Portman a Bacon number of 2.
British actor Colin Firth has an Erdős–Bacon number of 6. Firth is credited as co-author of a neuroscience paper, "Political Orientations Are Correlated with Brain Structure in Young Adults", after he suggested on BBC Radio 4 that such a study could be done. Another author of that paper, Geraint Rees, has an Erdős number of 4, which gives Firth an Erdős number of 5. Firth's Bacon number of 1 is due to his appearance in Where the Truth Lies.
Kristen Stewart has an Erdős–Bacon number of 7; she is credited as a co-author on an artificial intelligence paper that was written after a technique was used for her short film Come Swim, giving her an Erdős number of 5, and she co-starred with Michael Sheen in Twilight, who co-starred with Bacon in Frost/Nixon, giving her a Bacon number of 2.
Misha Collins has an Erdős–Bacon number of 6. He co-authored a peer-reviewed paper on The 2D shape structure dataset: A user annotated open access database May 2016 with Axel Carlier, Kathryn Leonard, Stefanie Hahmann and Geraldine Morin, giving him an Erdős number of 4. and he co-starred with Kiefer Sutherland in 24, who co-starred with Bacon in A Few Good Men, giving him a Bacon number of 2.
Albert M. Chan has Erdős–Bacon number of 4. He co-authored a peer-reviewed paper on OFDM, giving him an Erdős number of 3. Chan appeared alongside Kevin Bacon in Patriots Day, giving him a Bacon number of 1.
Others
Elon Musk, who is neither a scientist nor an actor, has an Erdős–Bacon number of 6. In 2010 Musk had a cameo in the film Iron Man 2. Since actor Mickey Rourke played a role in both Iron Man 2 and in Diner where also Kevin Bacon played a role, Musk has a Bacon number of 2. In 2021 Musk coauthored a peer-reviewed scientific paper on COVID-19 together with Pardis Sabeti, among others. Since Sabeti has an Erdős number of 3, Musk has an Erdős number of 4 and consequently an Erdős–Bacon number of 6.
Sergey Brin has an Erdős number of 3 through papers with Jeffrey Ullman and Ronald Graham, and he has two cameos in the 2013 comedy The Internship, leading to a Bacon number of 2 via Rose Byrne and consequently an Erdős–Bacon number of 5.
Bill Gates has an Erdős number of 4 and in 1987 he participated in a short mockumentary titled Citizen Steve about Steven Spielberg, where he co-starred with Whoopi Goldberg, giving him a Bacon number of 2 and consequently an Erdős–Bacon number of 6.
Table
Notes:
References
Mathematics literature
Separation numbers
Bacon Number
Mathematics and culture | Erdős–Bacon number | Mathematics | 1,456 |
7,224,368 | https://en.wikipedia.org/wiki/Bengt%20Holmstr%C3%B6m | Bengt Robert Holmström (born 18 April 1949) is a Finnish economist who is currently Paul A. Samuelson Professor of Economics (Emeritus) at the Massachusetts Institute of Technology. Together with Oliver Hart, he received the Central Bank of Sweden Nobel Memorial Prize in Economic Sciences in 2016.
Early life and education
Holmström was born in Helsinki, Finland, on 18 April 1949, and belongs to the Swedish speaking minority of Finland. He received his B.S. in mathematics and science from the University of Helsinki in 1972. He also received a Master of Science degree in operations research from Stanford University in 1975.
He received his Ph.D. from the Graduate School of Business at Stanford in 1978. He moved to the United States in 1976.
Career
He worked as a corporate planner from 1972 until 1974, then was an assistant professor at the Hanken School of Economics from 1978 until 1979. He served as an associate professor at the Kellogg Graduate School of Management at Northwestern University (1979–1983) and as the Edwin J. Beinecke Professor of Management at Yale University’s School of Management (1983–1994). Holmström was elected Alumnus of The Year by the University of Helsinki Alumni Association in 2010.
He has been on the faculty of M.I.T. since 1994, when he was appointed professor of economics and management at the department of economics and Sloan School of Management.
Holmström is particularly well known for his work on principal-agent theory. His work made seminal advances in understanding contracting in the presence of uncertainty. More generally, he has worked on the theory of contracting and incentives especially as applied to the theory of the firm, to corporate governance and to liquidity problems in financial crises. He praised the taxpayer-backed bailouts by the US government during the financial crisis of 2007–2008 and emphasizes the benefits of opacity in the money market.
Holmström was elected member of the Finnish Society of Sciences and Letters in 1992 and an honorary member of the same society in 2016. He is a fellow of the American Academy of Arts and Sciences, the Econometric Society, the European Economic Association and the American Finance Association, and a foreign member of the Royal Swedish Academy of Sciences and the Finnish Academy of Science and Letters. In 2011, he served as President of the Econometric Society. He holds honorary doctorate degrees from the Stockholm School of Economics, Sweden, the University of Vaasa and the Hanken School of Economics in Finland.
Holmström was a member of Nokia's board of directors from 1999 until 2012. He was a member of the Board of the Aalto University from 2008 until 2017.
Accolades
He was awarded the 2012 Banque de France-TSE Senior Prize in Monetary Economics and Finance, the 2013 Stephen A. Ross Prize in Financial Economics and the 2013 Chicago Mercantile Exchange – MSRI Prize for Innovative Quantitative Applications.
In 2016, Holmström won the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel together with Oliver Hart "for their contributions to contract theory".
Personal life
He is married to Anneli Holmström and they have one son.
Publications
Holmström, Bengt, 1972. "En icke-linear lösningsmetod för allokationsproblem". University of Helsinki.
Holmström, Bengt, 1979. "Moral Hazard and Observability," Bell Journal of Economics, 10(1), pp. 74–91.
Holmstrom, Bengt. "Moral hazard in teams." The Bell Journal of Economics (1982): 324–340.
Holmstrom, Bengt. "Equilibrium long-term labor contracts." The Quarterly Journal of Economics (1983): 23–54. 23
Holmström, B., 1999. Managerial incentive problems: A dynamic perspective. The Review of Economic Studies, 66(1), pp. 169–182.169–182
Holmström, Bengt, and Paul Milgrom, 1991. "Multitask Principal-Agent Analyses: Incentive Contracts, Asset Ownership, and Job Design," Journal of Law, Economics, and Organization, 7, 24–52.
Holmstrom, B. and Milgrom, P., 1994. The firm as an incentive system. The American Economic Review, pp. 972–991. 972–991.
Holmström, Bengt, and John Roberts, 1998. "The Boundaries of the Firm Revisited," Journal of Economic Perspectives, 12(4), pp. 73–94
Holmström, Bengt, and Jean Tirole, 1998. "Private and Public Supply of Liquidity," Journal of Political Economy, 106(1), pp. 1–40.
References
External links
including the Prize Lecture 8 December 2016 Pay for Performance and Beyond
|-
1949 births
Living people
Finnish business theorists
20th-century Finnish economists
Finnish Nobel laureates
Game theorists
Information economists
Stanford Graduate School of Business alumni
Stanford University alumni
MIT Sloan School of Management faculty
Members of the Royal Swedish Academy of Sciences
Fellows of the American Academy of Arts and Sciences
Fellows of the Econometric Society
Presidents of the Econometric Society
Swedish-speaking Finns
Nokia people
Finnish expatriates in the United States
Nobel laureates in Economics
21st-century Finnish economists
MIT School of Humanities, Arts, and Social Sciences faculty
Fellows of the European Economic Association | Bengt Holmström | Mathematics | 1,076 |
34,474,593 | https://en.wikipedia.org/wiki/Jane%27s%20Military%20Communications | Jane's Military Communications is an annual reference book (also published online) covering military communications and advances in the equipment used by various armed forces. Published by Jane's Information Group, a subsidiary of IHS Inc., it purports to be "the most comprehensive military communications information resource available." The former European editor of the Journal of Electronic Defense, John Williamson, was appointed editor in 1984. Previously R. J. Raggett was the editor.
Rodney Cowton, Defence Correspondent of the Times reviewed Jane's Military Communications 1983. Mr Raggett provided shipboard communications analysis of the Falklands Conflict from the British perspective: facilities for shipboard information storage and processing too small; backlogs of up to 1,000 messages; rooms not large enough to handle increased people traffic of the war environment; Argentines were able to intercept insecure communications. In 1983 these problems were considered "inevitable" considering the volume of up to 250,000 messages. 'Bob' Raggett predicted in the introduction that, by 2000, "electronic systems could render a nuclear attack by an unfriendly power virtually impossible".
In 1983 the publication cost £55.00 ().
The 2011–2012 Yearbook, containing 2,500 images and 2,600 entries, was priced at £540.00 with online access costing £1,850.00.
References
Yearbooks
Military communications
Janes Information Services | Jane's Military Communications | Engineering | 288 |
30,541,968 | https://en.wikipedia.org/wiki/James%20Hutton%20Institute | The James Hutton Institute is an interdisciplinary scientific research institute in Scotland established in 2011, through the merger of Scottish Crop Research Institute (SCRI) and the Macaulay Land Use Research Institute. The institute, named after Scottish geologist James Hutton, one of the leading figures of the Scottish Enlightenment, combines existing Scottish expertise in agricultural research, soils and land use, and works in fields including food and energy security, biodiversity, and climate change. With more than 600 employees, the institute is among the largest research centres in the UK. It is a registered charity under Scottish law.
The institute has its main offices in Aberdeen and Dundee with farms and field research stations at Glensaugh and Balruddery. The Dundee site also hosts the Plant Sciences department of the University of Dundee.
The James Hutton Institute also formally contains Biomathematics and Statistics Scotland (BioSS) which has staff based in Edinburgh, Dundee, Aberdeen and Ayr. BioSS undertakes research, consultancy and training in mathematics and statistics as applied to agriculture, the environment, food and health. Strategic oversight of the development of BioSS is provided by a Strategic Planning Group composed of senior representatives from BioSS' principal stakeholders.
BioSS and the James Hutton Institute are two of a family of six organisations termed the Main Research Providers for the Scottish Government Rural and Environment Research and Analytical Services Division (RESAS).
In 2012, the institute announced that it was formally joining the Natural Capital Initiative, a leading UK partnership that brings together policymakers, scientists, business, industry to find the most effective ways safeguard important ecosystems and natural capital.
Projects led by the institute to establish an International Barley Hub and an Advanced Plant Growth Centre in Dundee have been supported through the Tay Cities Deal with a £62m investment.
References
Agricultural organisations based in Scotland
Research institutes in Scotland
Environmental research institutes
Agricultural research institutes in the United Kingdom
2011 establishments in Scotland
Organisations based in Aberdeen
Organisations based in Dundee
2011 in science
Public bodies of the Scottish Government
Government agencies established in 2011
Science and technology in Aberdeen
Science and technology in Dundee
Charities based in Scotland | James Hutton Institute | Environmental_science | 415 |
74,462,180 | https://en.wikipedia.org/wiki/Simulator%20pedal | A simulator pedal, sim pedal or gaming pedal is a pedal used in a simulator for entertainment or training. Common examples are throttle and brake pedals for driving simulators, and rudder pedals for flight simulators. For minimum latency, they are often connected to a computer or gaming console via cabling, for example with USB-C.
For video game entertainment such as arcade games or for beginner sim racers, inexpensive pedals are often used, while for serious training and professional sim racing there are more expensive models, and these are sometimes coupled with a direct-drive sim racing wheel.
Although new sim racers are often more concerned with the steering wheel, many experienced racers recommend putting more money into the pedals (and a sturdy sim rig) and rather purchase a less expensive steering wheel if one has to prioritize.
Sensors
The transducer or sensor on inexpensive pedals is often based on potentiometers eller Hall effect sensors, while more expensive pedals use load cells (or sometimes load cells combined with hydraulics). Gaming pedals used with computer games are basically electronic brake-by-wire pedals and electronic throttle-by-wire pedals.
Mechanics
The pedals can be designed with complex geometries consisting of arms, springs and dampers with the intention of creating a "natural" feel with progressive and repeatable resistance so that the driver can perform more consistently in competitions. This is particularly important for the brake pedal in sim racing. For some affordable pedals, there are upgrade kits and homemade solutions available with the aim of imitating the feeling one can get with more expensive pedals.
Haptics
In 2022, the Finnish company Simucube launched ActivePedal, the world's first mass-produced simpedal with haptic technology. Co-founder and technical director Tero Kontkanen from Simucube claims that such active pedals in the long run will have a greater impact on sim racing than direct-driven sim racing wheels.
Haptic pedals can be used to give the driver of a car simulator valuable feedback (in the form of force-feedback and vibrators) based on telemetry from what happens to the car's tires against the ground in the simulator. Haptics are primarily useful for the brake pedal. In addition to giving the ability to sense the transition from static to kinetic friction when skidding, haptic pedals can also be used to simulate pulsations in the pedals of cars with anti-lock brakes or traction control.
Automotive pedals
The most common sim racing pedal setup is two asymmetric pedals with a brake pedal and an accelerator pedal. A clutch pedal can often be purchased separately as an optional extra, and can, for example, be relevant the driver desires to realistically drive historic racing cars with a manual gear stick. Some inexpensive pedal kits come with three pedals, and some sim steering wheel bundles also come with pedals included. A clutch pedal is rarely necessary in sim racing.
In case the seat and cockpit setup is to mimic a close to lying Formula style seating position it can be beneficial to be able to mount the pedals inverted such that the pedals hang downwards instead of coming up from the floor as normal. Many pedals can easily be inverted by mounting them upside down, but not all pedal sets can be inverted. As for the more common upright GT style seating position, which is more comfortable for longer sessions and therefore will be more relevant for most drivers, it is of less importance whether the pedal can be inverted or not.
Flight pedals
Rudder pedals for flight simulators simulate rudder control (and possibly toe brakes), and come in pairs with one pedal for each foot. The pedals are interconnected and synchronized so that one pedal flips out when the other is pressed in.
Bicycle pedals
There are indoor exercise bikes that can be used for computer games. Alternatively, some bicycle trainers have sensors to measure the rider's performance, including power (watts), cadence(r/min), virtual speed and heart rate, and these measurements can be connected to software or apps so that one can compete against oneself in a cycling game or against other riders over the internet. Analysis of the measurements can also help with the cyclist's training.
See also
Esports
Gaming chair
Joystick or yoke
Rudder pedals, a foot-operated interface for steering the rudder of an airplane
Sim racing wheel
Throttle pedal or throttle lever
References
Game controllers
Computer peripherals | Simulator pedal | Technology | 911 |
27,244,622 | https://en.wikipedia.org/wiki/Jeroen%20van%20den%20Brink | Jeroen van den Brink (born November 18, 1968) is a theoretical condensed matter physicist, director at the Leibniz Institute for Solid State and Materials Research, IFW Dresden and professor at the Dresden University of Technology in Germany. Van den Brink is known for contributions to the field of strongly correlated materials, in particular for proposals on magnetic and orbital ordering, mechanisms for multiferroicity and the theory of Resonant Inelastic X-Ray Scattering (RIXS).
He obtained a PhD from the University of Groningen in 1997, was a professor of theoretical condensed matter physics working at Leiden University from 2002–2009 and in 2009 visiting professor at the
Stanford Institute for Materials and Energy Science.
References
External links
IFW Dresden
Lorentz Institute, Leiden University
Living people
Theoretical physicists
1968 births
Academic staff of Leiden University | Jeroen van den Brink | Physics | 168 |
10,614,125 | https://en.wikipedia.org/wiki/Anderson%27s%20theorem | In mathematics, Anderson's theorem is a result in real analysis and geometry which says that the integral of an integrable, symmetric, unimodal, non-negative function f over an n-dimensional convex body K does not decrease if K is translated inwards towards the origin. This is a natural statement, since the graph of f can be thought of as a hill with a single peak over the origin; however, for n ≥ 2, the proof is not entirely obvious, as there may be points x of the body K where the value f(x) is larger than at the corresponding translate of x.
Anderson's theorem, named after Theodore Wilbur Anderson, also has an interesting application to probability theory.
Statement of the theorem
Let K be a convex body in n-dimensional Euclidean space R that is symmetric with respect to reflection in the origin, i.e. K = −K. Let f : R → R be a non-negative, symmetric, globally integrable function; i.e.
f(x) ≥ 0 for all x ∈ R;
f(x) = f(−x) for all x ∈ Rn;
Suppose also that the super-level sets L(f, t) of f, defined by
are convex subsets of Rn for every t ≥ 0. (This property is sometimes referred to as being unimodal.) Then, for any 0 ≤ c ≤ 1 and y ∈ Rn,
Application to probability theory
Given a probability space (Ω, Σ, Pr), suppose that X : Ω → R is an R-valued random variable with probability density function f : Rn → [0, +∞) and that Y : Ω → R is an independent random variable. The probability density functions of many well-known probability distributions are p-concave for some p, and hence unimodal. If they are also symmetric (e.g. the Laplace and normal distributions), then Anderson's theorem applies, in which case
for any origin-symmetric convex body K ⊆ Rn.
References
Theorems in geometry
Eponymous theorems of geometry
Probability theorems
Theorems in real analysis | Anderson's theorem | Mathematics | 435 |
3,727,062 | https://en.wikipedia.org/wiki/Moisture%20stress | Moisture stress is a form of abiotic stress that occurs when the moisture of plant tissues is reduced to suboptimal levels. Water stress occurs in response to atmospheric and soil water availability when the transpiration rate exceeds the rate of water uptake by the roots and cells lose turgor pressure. Moisture stress is described by two main metrics, water potential and water content.
Moisture stress has an effect on stomatal opening, mainly causing a closure in stomata as to reduce the amount of carbon dioxide assimilation. Closing of the stomata also slows the rate of transpiration, which limits water loss and helps to prevent the wilting effects of moisture stress. This closing can be triggered by the roots sensing dry soil and in response producing the hormone ABA which when transported up the xylem into the leaves will reduce stomatal conductance and wall extensibility of growing cells. This lowers the rates of transpiration, photosynthesis and leaf expansion. ABA also increases the loosening of growing root cell walls and in turn increases root growth in an effort to find water in the soil.
Phenotypic response of plants to long-term water stress was measured in corn and showed that plants respond to water stress with both an increase in root growth both laterally and vertically. In all Droughted conditions the corn showed decrease in plant height and yield due to the decrease in water availability.
Genes induced during water-stress conditions are thought to function not only in protecting cells from water deficit by the production of important metabolic proteins but also in the regulation of genes for signal transduction in the water-stress response. There are four pathways that have been described that show the plants genetic response to moisture stress; two are ABA dependent while two are ABA independent. They all affect gene expression that increases the plants water stress tolerance.
The effects of moisture stress on photosynthesis can depend as much on the velocity and degree of photosynthetic recovery, as it depends on the degree and velocity of photosynthesis decline during water depletion. Plants that are subjected to mild stress can recover in 1–2 days however, plants subjected to severe water stress will only recover 40-60% of its maximum photosynthetic rates the day after re watering and may never reach maximum photosynthetic rates. The recovery from moisture stress starts with an increase in water content in leaves reopening the stomata then the synthesis of photosynthetic proteins.
See also
Nonlimiting water range
Permanent wilting point
Soil plant atmosphere continuum
Stomata
References
Agricultural soil science
Irrigation
Plant physiology | Moisture stress | Biology | 523 |
43,181,179 | https://en.wikipedia.org/wiki/Cable%20entry%20system | Cable entry systems are used for routing electrical cables, corrugated conduits or pneumatic and hydraulic hoses into switch cabinets, electrical enclosures, control panels and machines or in large heavy-duty vehicles, rolling stock and ships. Possible requirements can be high ingress protection rates or integrated strain relief.
It is being differentiated between entry systems for routeing standard cables (without connectors) with a high packing density and split cable entry systems which enable routeing of pre-terminated cables (with connectors) or complete cable harnesses.
History
From the 50s on, machines and switch cabinets were more and more wired by using heavy-duty industrial connectors but the increasing cost pressure forced engineers to look for more cost-effective solutions and to decrease the risk of miswiring. In the 90s cable entry systems have been developed as an alternative to heavy-duty industrial connectors and cable glands.
Cable entry systems for cables without connectors
For routing of standard cables and other electrical, pneumatic or hydraulic lines through machine, panel or enclosure walls, cable glands, self-sealing grommets or gland plates can be used to seal the cut-outs required for passing the cables through. This protects the inside of an enclosure or machine from dirt, dust or liquids.
Cable glands and self-sealing grommets are usually designed for entering single or just a few cables. By utilising a gland plate, many cables with different diameters can be routed. Depending on the type, very high cable densities or ingress protection classes up to IP66/IP68 (according to IEC 60529) can be achieved.
Even for industries with hygiene critical environments (for example, food industry, pharmaceutical industry) membrane-based cable entry plates are available in the market as alternatives to hygienic stainless steel cable glands. These cable entry plates are characterised by a particularly smooth surface without dirt collecting recesses (EHEDG compliant Hygienic Design) and FDA compliant material.
Split cable entry systems for cables with connectors
For routing cables which are already assembled with connectors, split cable entry systems have been developed. The divisibility of these systems provides two advantages. The warranty on pre-terminated cables remains since the connectors don’t have to be cut and soldered again after entering the cables. The other advantage is that assembly can be done subsequently because the split cable entries are usually built around the existing lines.
Most split cable entries consist of a split hard frame, made of plastic or sometimes stainless steel (e.g. utilised in food industry) and one or several split sealing grommets, usually made of elastomer. The grommet matching the cable diameter is placed around the cable and fixed inside the cable entry frame. Thus allowing strain relief for the cables (in some cases according to EN 62444) as well as ingress protection of up to IP66/IP68.
Frame sizes and standards
Cable entries are offered in different sizes, but most of them are based on cut-out dimensions and drilling templates for standard industrial connectors (10-pin, 16-pin, 24-pin). Round cable entry plates are usually produced in metric standard sizes (M16 – M63)
Since cable entry systems are utilised in many different applications, it is very important to comply with standards like e.g. IP rating (according to EN 60529), UL recognition, DNV-GL listing (for marine applications), national or European railway standards or ATEX certifications that enable use in potentially explosive atmospheres.
See also
Ring main unit
References
Electrical systems | Cable entry system | Physics | 743 |
68,990,485 | https://en.wikipedia.org/wiki/Camp%20Beagle | Camp Beagle is an ongoing protest camp set up in June 2021 by animal rights activists outside of MBR Acres, a breeding facility for beagles used in laboratory research, in Wyton, Cambridgeshire. As of May 2024, It is the longest-lasting protest camp of its kind, where protesters have maintained a permanent presence, as they want the site to be closed down.
Background
MBR Acres is owned by the American company Marshall BioResources (MBR). Up to 2,000 beagles are bred at the facility each year; they are sold at the age of around 16 weeks to be used for drugs and chemical testing. Since 2020, protests have been held around the facility by animal rights movements.
History
The camp was first set up in June 2021; footage of dogs from the facility published by the Daily Mirror led to increased support of the campaign. The protesters argue that the facility is factory farming beagles; MBR has issued a statement saying that the protesters are misinformed and that breeding of animals is essential for medical research. The statement also stated that the facility is both regulated and frequently inspected by the Home Office which enforces strict laws around animal welfare in research facilities.
Actors Ricky Gervais and Peter Egan have voiced their support for the facility to be closed down. In August 2021 The Times Newspaper published a letter signed by in support of MBR Acres and its contribution to medical research to nineteen scientific societies and organizations.
On 28 August, Camp Beagle coordinated a protest with Animal Rebellion at Smithfield Market in London.
15 activists were arrested on 31 August for "suspected obstruction of the highway or of criminal damage."
Following a High Court injunction hearing instigated by MBR Acres, it was ruled, on 5 October, that the camp was allowed to remain, with the provision that activists must remain at least 10 metres from the gates.
In October 2021, a Freedom of Information Request revealed that Cambridge Constabulary spent from 27 June to 14 September 2021 on policing the camp. According to protesters, "more than 40 officers and 10 police vans" were used during a day of transportation in October. The following month, the singer Will Young handcuffed himself to the gates of the facility, describing the facility as a "puppy farm".
In December 2022, activists from Animal Rebellion freed 18 beagles from the facility. Two beagles known as Libby and Love – that were recovered by police – were later returned to the facility, and 14 people were arrested as part of an investigation into burglary and aggravated trespass at the site. In July 2023, nine campaigners were found guilty of aggravated trespass, and were given conditional discharges or fines. The Crown Prosecution Service otherwise dropped charges of burglary against 12 people, stating that "the legal test for going ahead had not been met".
On 25 May 2024, an estimated 400–500 protesters descended upon the camp, as part of a protest billed as 'Operation 1,000', in an attempt to attract 1,000 protesters to the camp. Cambridgeshire police closed the nearby road due to the number of demonstrators in attendance.
See also
Brown Dog Affair
Consort beagles campaign
Save the Hill Grove Cats
Save the Newchurch Guinea Pigs
Stop Huntingdon Animal Cruelty
Shamrock Farm
References
2021 protests
2022 protests
2023 protests
2024 protests
Animal rights protests
Animal testing in the United Kingdom
Animal welfare and rights in England
Anti-vivisection movement
Dog breeding
Dogs in the United Kingdom
Protest camps
Protests in England
Organisations based in Cambridgeshire | Camp Beagle | Chemistry | 709 |
3,034,653 | https://en.wikipedia.org/wiki/Roboteer | The word roboteer refers to those with interests or careers in robotics. It dates back to the 1930s and is also used in 'Future Shock' (1970).
The term roboteer was used by Barbara Krasnov for a story on Deb Huglin, owner of the Robotorium, Inc., in New York City in the early 1980s. Huglin was a lightweight-robotics applications consultant, sculptor, and repatriation archeologist. Huglin worked with Jim Henson on the design and uses of the robotic mit controller for his experimental television series "Fraggle Rock". Huglin died in a fall in the wilderness near Hemet, California in 2008.
See also
Roboticist
References
External links
Debbie the Roboteer on IMDB.
Robotics | Roboteer | Engineering | 154 |
6,024,815 | https://en.wikipedia.org/wiki/Lymphoepithelioma | Lymphoepithelioma is a type of poorly differentiated nasopharyngeal carcinoma characterized by prominent infiltration of lymphocytes in the area involved by tumor. Lymphoepithelioma is also known as "class III nasopharyngeal carcinoma" in the WHO classification system. It has a high tendency to metastasize and is responsive to radiotherapy. Most cases are associated with Epstein–Barr virus infection.
Lymphoepithelioma-like carcinomas are carcinomas that arise outside of the nasopharynx, but resemble a lymphoepithelioma histologically. Lymphoepithelioma-like carcinomas may be found in almost any epithelial organ, including the lung, thymus, breast, colon, endometrium, prostate, and skin, as well as urinary bladder, trachea, esophagus, stomach, salivary glands, vulva.
History
Lymphoepithelioma may also be referred to as Schmincke–Regaud tumor, after the German pathologist Alexander Schminke and French radiologist Claude Regaud.
References
External links
Carcinoma
Histopathology
Epstein–Barr virus–associated diseases | Lymphoepithelioma | Chemistry | 275 |
64,126,151 | https://en.wikipedia.org/wiki/Sequentially%20complete | In mathematics, specifically in topology and functional analysis, a subspace of a uniform space is said to be sequentially complete or semi-complete if every Cauchy sequence in converges to an element in .
is called sequentially complete if it is a sequentially complete subset of itself.
Sequentially complete topological vector spaces
Every topological vector space is a uniform space so the notion of sequential completeness can be applied to them.
Properties of sequentially complete topological vector spaces
A bounded sequentially complete disk in a Hausdorff topological vector space is a Banach disk.
A Hausdorff locally convex space that is sequentially complete and bornological is ultrabornological.
Examples and sufficient conditions
Every complete space is sequentially complete but not conversely.
For metrizable spaces, sequential completeness implies completeness. Together with the previous property, this means sequential completeness and completeness are equivalent over metrizable spaces.
Every complete topological vector space is quasi-complete and every quasi-complete topological vector space is sequentially complete.
See also
Cauchy net
Complete space
Complete topological vector space
Quasi-complete space
Topological vector space
Uniform space
References
Bibliography
Functional analysis
Topological vector spaces | Sequentially complete | Mathematics | 235 |
33,577,089 | https://en.wikipedia.org/wiki/Suvorexant | Suvorexant, sold under the brand name Belsomra, is an orexin antagonist medication which is used in the treatment of insomnia. It is indicated specifically for the treatment of insomnia characterized by difficulties with sleep onset and/or maintenance in adults. Suvorexant helps with falling asleep faster, sleeping longer, being awake less in the middle of the night, and having better quality of sleep. Its effectiveness is modest, and is similar to that of other orexin antagonists, but is lower than that of benzodiazepines and Z-drugs. Suvorexant is taken by mouth.
Side effects of suvorexant include somnolence, daytime sleepiness and sedation, headache, dizziness, abnormal dreams, dry mouth, and impaired next-day driving ability. Rarely, sleep paralysis, sleep-related hallucinations, complex sleep behaviors like sleepwalking, and suicidal ideation may occur. Tolerance, dependence, withdrawal, and rebound effects do not appear to occur significantly with the medication. Suvorexant is a dual orexin receptor antagonist (DORA). It acts as a selective dual antagonist of the orexin OX1 and OX2 receptors. The medication has an intermediate elimination half-life of 12hours and a time to peak of about 2 to 3hours. Unlike benzodiazepines and Z-drugs, suvorexant does not interact with GABA receptors, instead having a distinct mechanism of action.
Clinical development of suvorexant began in 2006 and it was introduced for medical use in 2014. The medication is a schedule IV controlled substance in the United States and may have a modest potential for misuse. In other places, such as Australia, suvorexant is a prescription-only medicine and is not a controlled drug. Suvorexant is not available in generic formulations. Besides suvorexant, other orexin receptor antagonists like lemborexant and daridorexant have also been introduced.
Medical uses
Suvorexant is used for the treatment of insomnia, characterized by difficulties with sleep onset and/or sleep maintenance, in adults. At a dose of 15 to 20mg and in terms of treatment–placebo difference, it reduces time to sleep onset by up to 10minutes, reduces time awake after sleep onset by about 15 to 30minutes, and increases total sleep time by about 10 to 20minutes. A 2017 systematic review and meta-analysis of randomized controlled trials of suvorexant for insomnia likewise found that the medication improved subjective sleep onset, subjective total sleep time, and subjective sleep quality when assessed at one to three months of treatment. The effectiveness of approved doses of suvorexant (≤20mg) in the treatment of insomnia is said to be modest.
Network meta-analyses have assessed the sleep-promoting effects of suvorexant and have compared them to those of other orexin receptor antagonists like lemborexant and daridorexant as well as to other sleep aids including benzodiazepines, Z-drugs, antihistamines, sedative antidepressants (e.g., trazodone, doxepin, amitriptyline, mirtazapine), and melatonin receptor agonists. A major systematic review and network meta-analysis of insomnia medications published in 2022 found that suvorexant had an effect size (standardized mean difference (SMD)) against placebo for treatment of insomnia at 4weeks of 0.31 (95% 0.01 to 0.62). Suvorexant appeared to be similarly effective at 4weeks to lemborexant (SMD 0.36, 95% CI 0.08 to 0.63) and daridorexant (SMD 0.23, 95% CI –0.01 to 0.48), whereas benzodiazepines and Z-drugs generally showed larger effect sizes (e.g., SMDs of 0.45 to 0.83) and antihistamines (e.g., doxepin, doxylamine, trimipramine) showed more similar efficacy (SMDs of 0.30 to 0.55).
Orexin receptor antagonists like suvorexant increase total sleep time predominantly by increasing rapid eye movement sleep (REM) sleep, whereas they have no effect on or even decrease non-rapid eye movement (NREM) sleep. This is in contrast to most other hypnotics, which either do not affect REM sleep or decrease it. The implications of these differences are not fully clear. Unlike certain other hypnotics like benzodiazepines and Z-drugs, orexin receptor antagonists do not disrupt sleep architecture, and this might provide more restful sleep.
It is unclear if suvorexant is safe among people with a history of substance addiction or alcoholism, as these individuals were excluded from clinical trials of suvorexant. A Cochrane review found suvorexant to be effective in the short-term treatment of sleep disturbances in people with dementia with few adverse effects. It is unknown if suvorexant is effective and safe for treatment of sleep problems in children and adolescents as suvorexant has not been studied in this context.
Suvorexant is approved for the treatment of insomnia by the United States Food and Drug Administration (FDA) at doses of 5 to 20mg and by the Australian Therapeutic Goods Administration (TGA) and Japanese Pharmaceuticals and Medical Devices Agency (PMDA) at doses of 15mg (in the elderly) and 20mg (in younger adults). In the United States, the recommended starting dose is 10mg and the maximum recommended dose is 20mg. Higher doses of 30 and 40mg were also submitted to regulatory agencies for approval but were not authorized due to lack of clearly superior efficacy to doses of 15 to 20mg and concerns about next-day effects and associated impairment (e.g., driving). In addition to the preceding doses, suvorexant has been assessed at higher doses of up to 100mg in clinical trials. These higher doses appeared to be more effective at promoting sleep than lower doses but produced greater next-day effects. Lower approved doses of suvorexant in the United States in the range of 5 to 10mg were not extensively evaluated in clinical trials.
The American Academy of Sleep Medicine's 2017 clinical practice guidelines recommend the use of suvorexant in the treatment of sleep-onset and sleep-maintenance insomnia along with various other sleep medications. Orexin receptor antagonists are not used as first-line treatments for insomnia due to their costs and concerns about possible misuse liability. Generic formulations of orexin receptor antagonists including suvorexant are not yet available.
Available forms
Suvorexant is available in the form of 5, 10, 15, and 20mg oral film-coated tablets. It is provided as 10- and 30-tablet blister packs as well as 3-tablet starter packs. The availability of these different packs varies by country.
Contraindications
Suvorexant is contraindicated in people with narcolepsy as it may worsen their symptoms. This is its only absolute contraindication. Suvorexant has not been studied in people with severe hepatic impairment and is not recommended in these individuals due to the likelihood of increased suvorexant exposure. On the other hand, suvorexant may be used in people with mild-to-moderate hepatic impairment as well as renal impairment of any severity and no dose adjustment is necessary in these situations. Concomitant use of suvorexant with strong CYP3A4 inhibitors is not recommended due to potential for increased suvorexant exposure while concomitant use of suvorexant with strong CYP3A4 inducers may result in loss of suvorexant exposure and effectiveness. Suvorexant should be used carefully in people with a history of drug misuse or alcoholism due to its drug-liking effects and possible misuse potential at doses higher than those approved for therapeutic use. Similarly, suvorexant should be used carefully in people with a history of depression or suicidality as it may rarely increase suicidal ideation. The medication is indicated for use in adults and the elderly but has not been studied in children and adolescents and hence is not recommended for these individuals.
Suvorexant has shown teratogenic effects in animals such as decreased body weight at doses much higher than the equivalents of those approved for therapeutic use in humans. Teratogenic effects with therapeutic doses of suvorexant in humans have not been established due to lack of research and available data. Suvorexant is pregnancy category C in the United States. It is unknown whether suvorexant is present in the breast milk, whether it affects lactation in breastfeeding women, or whether it affects breastfed infants. However, suvorexant has been found to be present in mammary milk in rats and this is likely to be the case in humans as well. Suvorexant should be used in pregnant and breastfeeding women only if the potential benefit justifies the potential for harm to the baby.
Side effects
Side effects of suvorexant (at doses of 15–20mg) include somnolence (7% vs. 3% for placebo) and headaches (7% vs. 6% for placebo). Somnolence with suvorexant appears to be dose-dependent, with rates of 2% at 10mg, 5% at 20mg, 10–12% at 40mg, and 11–12% at 80mg, relative to 0.4% for placebo. Less common side effects (at 15–20mg) may include dizziness (3% vs. 2% for placebo), abnormal dreams (2% vs. 1% for placebo), diarrhea (2% vs. 1% for placebo), dry mouth (2% vs. 1% for placebo), upper respiratory tract infection (2% vs. 1% for placebo), and cough (2% vs. 1% for placebo). High doses of suvorexant (80mg) have also been found to produce greater incidence of dizziness (5% vs. 0% for placebo) and abnormal dreams (5% vs. 1% for placebo).
Less commonly, suvorexant may cause sleep paralysis, hypnagogic and hypnopompic hallucinations, and complex sleep behaviors (0.2–0.6% vs. 0% for placebo). Complex sleep behaviors include sleepwalking, sleep-driving, and engaging in other activities while not completely awake (e.g., making or eating food, making phone calls, and having sex). Other narcoleptic-like symptoms such as cataplexy (sudden weakness or paralysis) may also rarely occur. Suvorexant may sometimes cause worsening of depression or suicidal ideation. A dose-dependent increase in suicidal ideation as assessed with the Columbia Suicide Severity Rating Scale was seen with suvorexant in clinical trials although rates were very low (0.2% (1/493) at low doses (15–20mg) and 0.4% (5/1291) at high doses (30–40mg) relative to 0.1% (1/1025) for placebo). It has also been stated however that suicidal ideation was reported in 0% to 1.6% of people taking 10 to 20mg and 3.4% to 8.2% taking 40 to 80mg relative to 0% to 0.3% with placebo. Suicidal ideation with suvorexant is considered to be mild. In any case, caution is warranted in use of suvorexant in people with depression, and people with worsening depression or suicidal thoughts should be promptly evaluated. Besides the clinical trial data, a case report of rapidly worsened depression and onset of suicidal ideation with suvorexant has been published.
The next-day effects of suvorexant have been studied. Besides the side effect of daytime somnolence, suvorexant may dose-dependently reduce alertness and motor coordination and impair driving ability. It may also increase the risk of falling asleep while driving. Driving ability was found to be impaired at doses of 20 and 40mg in clinical studies. Driving impairment may also occur with lower doses of suvorexant due to variations in individual sensitivity to the medication. In three of four studies, 30mg suvorexant had no influence on next-day memory or balance, whereas in the remaining study, there was a decrease in morning word recall with 40mg and an increase in body sway with 20 and 40mg doses. In another study in elderly people who were awakened in the night, impaired balance was present at 1.5hours after taking 30mg suvorexant whereas memory was unaffected.
A 2017 systematic review and meta-analysis of suvorexant for the treatment of insomnia found that the medication significantly increased the rate of somnolence by 3.5-fold, daytime sleepiness/sedation by 3.1-fold, fatigue by 2.1-fold, abnormal dreams by 2.1-fold, and dry mouth by 2.0-fold. Conversely, suvorexant did not significantly differ from placebo in the rates of any other assessed adverse effects. This included back pain, diarrhea, dizziness, falls, headache, car accidents/traffic violations, nasopharyngitis, nausea, potential drug misuse, suicidal ideation, complex sleep behaviors, hypnagogic or hypnopompic hallucinations, and sleep paralysis. The overall risk of any adverse event was increased 1.07-fold while discontinuation due to adverse events was unchanged ( = 0.93, 95% 0.60 to 1.44).
Tolerance, dependence, withdrawal, and rebound effects do not appear to occur with suvorexant in the treatment of insomnia at studied doses. In three-month clinical studies, no rebound insomnia as assessed by measures of sleep onset or maintenance was observed with discontinuation of suvorexant at doses of 15 to 40mg. Similarly, no withdrawal effects were observed with discontinuation of suvorexant at these doses. However, in other reports, some tolerance as assessed by diminishing somnolence and rebound insomnia upon discontinuation has been noted.
The orexin neuropeptides augment the signaling of the mesolimbic dopamine reward pathway and are thought to potentiate hedonic tone. Conversely, low orexin signaling may result in low hedonic tone and orexin receptor antagonists are of interest for the potential treatment of addiction. In line with these findings, suvorexant and other orexin receptor antagonists have not shown misuse liability in animal studies in rats and non-human primates. Paradoxically however, orexin receptor antagonists, including suvorexant, lemborexant, and daridorexant, have consistently shown drug-liking responses in human studies of recreational sedative users. Suvorexant at higher-than-approved doses (40, 80, and 150mg vs. 20mg maximum recommended dose) showed similar drug liking to the Z-drug zolpidem (15 and 30mg) in such individuals. On the other hand, it showed lower misuse potential on all other measures (including an overall rate of misuse potential adverse event of 58% for zolpidem and 31% for suvorexant). In another study, suvorexant at a dose of 150mg showed greater drug liking than daridorexant (50mg) but similar drug liking to zolpidem (30mg) and higher doses of daridorexant (100–150mg) in recreational sedative users. There was no apparent dose–response relationship for positive measures of misuse potential with suvorexant, in contrast to zolpidem. In the phase III clinical trials, misuse potential adverse events were reported in 3.0% with placebo, 4.1% with 15 or 20mg suvorexant, and 2.6% with 30 or 40mg suvorexant. The misuse liability of suvorexant is considered to be at most modest, and further research is needed to characterize the misuse potential of orexin receptor antagonists. In any case, suvorexant is a controlled substance in the United States due to concerns about the possibility of misuse.
Besides its subjective side effects, suvorexant has been found to cause dose-dependent increases in serum cholesterol levels in clinical trials. These changes in cholesterol levels were +1.2mg/dL at 10mg, +2.3mg/dL at 20mg, +3.1mg/dL at 40mg, and +6.0mg/dL at 80mg relative to –3.7mg/dL for placebo. Although the increases in cholesterol levels with approved doses of suvorexant (10–20mg) are small, they could be important over a long duration of treatment.
Early studies in rodents found that orexins (derived from Greek "orexis" meaning "appetite") stimulate appetite, feeding behavior, and weight gain while orexin receptor antagonists block these effects. However, subsequent animal studies were more mixed, with the effects being limited and depending on the animal strain. In humans, orexin receptor antagonists including suvorexant have not been found to affect body weight in rigorous clinical trials that lasted up to 12 to 14months.
Overdose
There is limited experience with overdose of suvorexant. Suvorexant has been assessed in single doses of as high as 240mg in clinical studies. The medication dose-dependently produces somnolence. High doses of suvorexant may also cause sleep-onset paralysis in some individuals (2% incidence at doses of 40–240mg). Treatment of suvorexant overdose is based on symptoms and is supportive. Gastric lavage may be used where appropriate whereas the value of dialysis has not been determined. Because suvorexant has high plasma protein binding, hemodialysis is not expected to enhance elimination of suvorexant.
Interactions
CYP3A4 inhibitors can increase exposure to suvorexant while CYP3A4 inducers can decrease exposure to suvorexant. Combination of suvorexant with the strong CYP3A4 inhibitor ketoconazole increased suvorexant overall exposure by 2.79-fold and peak levels by about 1.25-fold, combination with the moderate CYP3A4 inhibitor diltiazem increased suvorexant overall exposure by 2.05-fold and peak levels by about 1.25-fold, and combination with the strong CYP3A4 inducer rifampin decreased suvorexant overall exposure by 88% and peak levels by about 65%. The elimination half-life of suvorexant (about 12hours for suvorexant alone) was increased to 19.4hours with ketoconazole and to 16.1hours with diltiazem while it was decreased to 7.7hours with rifampin. Concomitant use of suvorexant with strong CYP3A4 inhibitors is not recommended, while lower doses of suvorexant are recommended with moderate CYP3A4 inhibitors (5mg starting dose and 10mg maximum dose generally). The substantial decrease in suvorexant exposure with strong CYP3A4 inducers may result in loss of effectiveness. Suvorexant does not appear to have been assessed in combination with moderate CYP3A4 inducers (e.g., modafinil).
Examples of important CYP3A4 modulators which are expected to interact with suvorexant include the strong CYP3A4 inhibitors boceprevir, clarithromycin, conivaptan, indinavir, itraconazole, ketoconazole, lopinavir, nefazodone, nelfinavir, posaconazole, ritonavir, saquinavir, telaprevir, and telithromycin (concomitant use not recommended); the moderate CYP3A4 inhibitors amprenavir, aprepitant, atazanavir, ciprofloxacin, diltiazem, dronedarone, erythromycin, fluconazole, fluvoxamine, fosamprenavir, grapefruit juice, imatinib, and verapamil (lower doses of suvorexant recommended); and the strong CYP3A4 inducers apalutamide, carbamazepine, efavirenz, enzalutamide, phenytoin, rifampin, and St. John's wort (expected to decrease suvorexant effectiveness).
Coadministration of suvorexant with other CNS depressants such as alcohol, benzodiazepines, opioids, and tricyclic antidepressants may increase the risk of CNS depression and daytime impairment. Alcohol and suvorexant do not appear to interact in terms of pharmacokinetics but consumption of alcohol in combination with suvorexant is not advised due to additive CNS depression. Dosage adjustment may be necessary when suvorexant is combined with other CNS depressants. Use of suvorexant in combination with other medications used in the treatment of insomnia is not recommended.
Suvorexant is not expected to cause clinically meaningful inhibition or induction of various cytochrome P450 enzymes and drug transporters. It has been found to not substantially influence the pharmacokinetics of midazolam (CYP3A4 substrate), warfarin (CYP2C9 substrate), digoxin (P-glycoprotein substrate), or combined birth control pills. However, coadministration of suvorexant with digoxin may result in slightly increased digoxin exposure due to inhibition of intestinal P-glycoprotein by suvorexant. Concentrations of digoxin should be monitored during coadministration of suvorexant and digoxin.
Pharmacology
Pharmacodynamics
Suvorexant acts as a selective dual antagonist of the orexin (hypocretin) receptors OX1 and OX2. These receptors are the biological targets of the endogenous wakefulness-promoting orexin neuropeptides orexin-A and orexin-B. The binding affinities (Ki) of suvorexant at the human orexin receptors are 0.55nM for the OX1 receptor and 0.35nM for the OX2 receptor. The antagonistic potencies or functional inhibition (Kb) of suvorexant at the human orexin receptors are 65nM for the OX1 receptor and 41nM for the OX2 receptor. Hence, suvorexant shows similar affinities and antagonistic activities at the OX1 and OX2 receptors in vitro. Suvorexant is highly selective for the orexin receptors over a large number of other targets (170 screened off-target receptors, enzymes, and transporters). In contrast to certain other sedatives and hypnotics, suvorexant is not a benzodiazepine or Z-drug and does not interact with GABA receptors.
Mechanism of action
Suvorexant is thought to exert its therapeutic effects in the treatment of insomnia by blocking the orexin receptors and thereby inhibiting the effects of the endogenous wakefulness-promoting orexin neuropeptides orexin-A and orexin-B. The orexin neuropeptides are produced exclusively by a relatively small population of 20,000 to 80,000 neurons located in the lateral hypothalamus in the brain. These neurons project widely throughout the brain and mediate excitatory signaling to key centers involved in sleep–wake regulation, including the noradrenergic locus coeruleus, histaminergic tuberomammillary nucleus, serotonergic raphe nucleus, and dopaminergic ventral tegmental area. The orexin system shows circadian rhythmicity in its activity, with high activity during waking and low to no activity during sleep or at night. Orexin system activity during wakefulness is also higher with behavioral activation and with high-intensity emotions.
Narcolepsy is a chronic sleep disorder characterized by excessive daytime sleepiness, cataplexy, sleep paralysis, and hypnagogic hallucinations, as well as sleep attacks and fragmented sleep. Narcolepsy with cataplexy, also known as type 1 narcolepsy, is thought to be caused by loss of orexin-producing neurons in the lateral hypothalamus, possibly mediated by autoimmune mechanisms related to environmental triggers in genetically susceptible individuals. There is an 80 to 100% loss of orexin-producing neurons in the lateral hypothalamus and very low or undetectable levels of orexin-A in cerebrospinal fluid in people with narcolepsy. Similarly, narcolepsy with cataplexy in dogs is caused by a mutation in the gene encoding the OX2 receptor, and knockout mice for genes encoding orexin system proteins such as prepro-orexin or the OX2 receptor show a narcolepsy-like phenotype. Although there is hypersomnolence in narcolepsy, people with the condition do not sleep more overall than normal individuals but instead experience more sleepiness and sleep during daytime in tandem with disturbed sleep at night. They do not usually feel well-rested during the day. Besides narcolepsy, the orexin system may also be involved in the etiology of insomnia. In addition, orexin signaling appears to change with age, and this may be involved in age-related sleep disturbances.
Orexin receptor antagonists may be expected to produce effects similar to those in narcolepsy. However, the effects of acute transient pharmacological antagonism of the orexin receptors are not necessarily the same as in the chronic and severe orexin deficiency in narcolepsy. Modulation of orexin signaling with orexin receptor antagonists produces effects that occur more at night when drug levels are high and less during the day when levels are low. In addition, long-term neural changes may develop in narcolepsy to compensate for the orexin deficiency in the condition. In animals and humans, orexin receptor agonists such as orexin-A and danavorexton dose-dependently produce wakefulness and locomotor activity while orexin receptor antagonists like suvorexant transiently reduce locomotor activity and dose-dependently promote sleep. Acute orexin receptor antagonists can promote sleep in animals to a greater extent than what occurs in narcolepsy-like orexin system loss. In addition, little to no cataplexy has been observed even with high doses of orexin receptor antagonists in animals and humans. It is unknown if long-term use of orexin receptor antagonists may produce compensatory neural changes or narcolepsy-like symptoms. An animal study of chronic high-dose suvorexant administration that showed development of narcolepsy-like changes suggests that this may be possible however.
Endogenous orexinergic tone is expected to play an important moderating influence in terms of the effects of orexin receptor modulators. As an example, rising orexin levels during the day may help to competitively offset the next-day residual effects of nightly-dosed orexin receptor antagonists.
Pharmacokinetics
Absorption
The absolute bioavailability of suvorexant is 82% at a dose of 10mg. Suvorexant exposure does not increase dose-proportionally over a dose range of 10 to 100mg, which is likely due to decreased absorption at higher doses. Exposure to suvorexant increases by about 75% with a doubling of dose from 20mg to 40mg. The time to peak levels of suvorexant is 2 to 3hours regardless of dose but with wide variation (range 30minutes to 8hours). Taking suvorexant with food does not modify suvorexant peak levels or area-under-the-curve levels (overall exposure) but does delay the time to peak concentrations by about 1.5hours. Steady-state levels of suvorexant with once-daily continuous administration are reached within 3days. Levels of suvorexant accumulate minimally, by about 1.2- to 1.6-fold, with repeated once-daily administration.
Distribution
The volume of distribution of suvorexant is approximately 49L. It crosses the blood–brain barrier and distributes into the central nervous system.
Suvorexant has high plasma protein binding (99.5%). It is bound to albumin and α1-acid glycoprotein (orosomucoid).
Metabolism
Suvorexant is metabolized primarily by hydroxylation via CYP3A enzymes. CYP2C19 also contributes to suvorexant metabolism to a minor extent. The major circulating forms are suvorexant and its metabolite hydroxysuvorexant. The hydroxysuvorexant (M9) metabolite is not expected to be pharmacologically active. It showed 10-fold lower affinity for the orexin receptors than suvorexant in vitro, was a substrate for P-glycoprotein making it unlikely to cross the blood–brain barrier, and did not show sedative effects in animal studies. Suvorexant also has several other minor metabolites.
Elimination
Suvorexant is eliminated mainly via metabolism. It is excreted primarily in feces (66%) predominantly as metabolites and to a lesser extent in urine (23%).
The elimination half-life of suvorexant at a dose of 40mg is 12.2hours, with a range of 8 to 19hours. In another study, the half-life of suvorexant was 15hours with a range of 10 to 22hours. In one study, the half-lives of suvorexant (mean ± SD) were 9.0 ± 7.2hours at 10mg, 10.8 ± 3.6hours at 50mg, and 13.1 ± 5.8hours at 100mg. With doses of 120 to 240mg, the half-lives of suvorexant were 12.1 to 14.5hours in healthy young males and 14.4 to 15.8hours in healthy young females. The half-life of suvorexant's inactive metabolite hydroxysuvorexant is similar to that of suvorexant.
Specific populations
Age and race do not influence the pharmacokinetics of suvorexant in a clinically meaningfully way. Exposure to suvorexant is slightly higher in women compared to men (Cmax 9% higher, AUC 17% higher), however dose adjustments based on gender are generally unnecessary. Suvorexant exposure is greater in people with higher body mass index, such as obese people (Cmax 17% higher, AUC 31% higher). This is particularly the case in obese women relative to non-obese women (Cmax 25% higher, AUC 46% higher). Suvorexant exposure with a single dose is not greater in people with moderate hepatic insufficiency compared to healthy individuals. However, the half-life of suvorexant at a dose of 20mg was prolonged from 14.7hours (range 10–22hours) to 19.1hours (range 11–49hours) in these individuals. Suvorexant exposure is unchanged in people with severe renal impairment and no dosage adjustment is necessary in these individuals. Similarly to hepatic impairment, the half-life of suvorexant was increased to 19.4hours when used in combination with the strong CYP3A4 inhibitor ketoconazole and to 16.1hours with the moderate CYP3A4 inhibitor diltiazem while it was decreased to 7.7hours with the strong CYP3A4 inducer rifampin.
Miscellaneous
The delayed time to peak levels (2–3hours) and long elimination half-life (12hours) of suvorexant are less than ideal for an insomnia medication as they result in a delayed onset of effect and significant next-day side effects such as daytime sedation. Orexin receptor antagonists with shorter half-lives and faster onsets of action are theoretically more optimal for therapeutic use as sleep aids. The ideal insomnia medication would not have a duration of action extending beyond about 8hours. Relative to suvorexant, daridorexant has a shorter half-life (8hours) while lemborexant has a longer half-life (17–55hours). However, although lemborexant has a longer terminal elimination half-life than suvorexant, it appears to be more rapidly cleared in the earlier phases of elimination. The investigational agents seltorexant and vornorexant, which are still in clinical trials, have comparatively very short half-lives in the range of 1.5 to 3hours.
Suvorexant dissociates from the orexin receptors slowly. As a result, its duration may be longer than that suggested by its circulating concentrations and half-life.
Chemistry
Suvorexant is a small-molecule compound. The chemical name of suvorexant is [(7R)-4-(5-chloro-2-benzoxazolyl)hexahydro-7-methyl-1H-1,4-diazepin-1-yl][5-methyl-2-(2H-1,2,3-triazol-2-yl)phenyl]methanone. Its molecular formula is C23H23N6O2Cl and its molecular weight is 450.92g/mol. Suvorexant is a white to off-white powder and is lipophilic and insoluble in water. It is structurally related to other orexin receptor antagonists like lemborexant, daridorexant, and seltorexant.
History
The orexin neuropeptides were discovered in 1998 and the role of the orexin system in the etiology of narcolepsy was identified between 1999 and 2000. Subsequent research further established the role of the orexin system in sleep–wake regulation. Due to the promising potential of orexin system modulation in the treatment of sleep disorders, these findings led to translational efforts to bring orexin receptor modulators to medicine as therapeutic agents.
Suvorexant was developed by Merck. It entered clinical development in 2006 and was first described in the medical literature in 2010. The medication was approved by the FDA for the treatment of insomnia in the United States on 13 August 2014. Suvorexant was initially released November 2014 in Japan, then later reached the United States in February 2015, Australia in November 2016, and Canada in November 2018. It was the first orexin receptor antagonist to be introduced for medical use, and was followed by lemborexant in 2019 and daridorexant in 2022. Development of almorexant (ACT-078573) and filorexant (MK-6096) was discontinued, while seltorexant (MIN-202, JNJ-42847922) and vornorexant (ORN-0829, TS-142) are still in clinical trials.
Suvorexant marketing exclusivity in the United States was set to expire in January 2023 and patent protection is set to expire in 2029 to 2033.
Society and culture
Names
Suvorexant is the generic name of the drug and its , , and . The medication was developed by Merck under the code name MK-4305 and is marketed under the brand name Belsomra.
Availability
Suvorexant has been marketed in the United States, Canada, Australia, Russia, and Japan. Although previously available, suvorexant appears to have been discontinued in Canada. It does not appear to be available in the United Kingdom or other European countries besides Russia.
Legal status
Suvorexant is a schedule IV controlled substance under the Controlled Substances Act in the United States. It is not a controlled drug in Australia, instead being classed as a prescription-only medicine (Schedule 4 (S4)) in this country.
Controversy
Public Citizen, a progressive consumer rights advocacy group, issued a letter in June 2013 urging the FDA not to approve suvorexant. In its reasoning, it cited marginal benefits and excessive potential for harm, including next-day effects like driving impairment and possible accidents. Consumer Reports also published articles encouraging consumers to avoid suvorexant due to it being expensive, having limited effectiveness, and posing safety concerns.
Research
Delirium
Suvorexant is under development for the treatment of delirium. As of October 2021, it is in phase III clinical trials for this indication.
Psychiatry
Suvorexant has been studied in the treatment of insomnia in people with psychiatric disorders such as depression and anxiety. It was reported to improve psychiatric symptoms and to decrease cortisol levels in these individuals. A phase IV clinical trial of suvorexant as an adjunct to antidepressant therapy in people with major depressive disorder and residual insomnia was underway as of 2019. Although orexin receptor antagonists including suvorexant could be useful for treatment of depression and anxiety, there is also indication that they could have harmful effects in these conditions (e.g., animal studies and suicidal ideation in clinical trials). More clinical research is needed to determine the place of orexin receptor antagonists in the treatment of people with depression and anxiety.
There is interest in suvorexant and other orexin receptor antagonists in the potential treatment of substance use disorders, including alcohol use disorder, cocaine use disorder, and opioid use disorder.
Alzheimer's disease
Suvorexant and other orexin receptor modulators are of interest for possible use in the prevention of Alzheimer's disease.
Diabetes
Suvorexant has been studied in people with type 2 diabetes and insomnia and has been reported to improve sleep and metabolic parameters in these individuals. The improvement in metabolic parameters appeared to be related to improved sleep.
References
Further reading
External links
Benzoxazoles
Chloroarenes
Diazepanes
Hypnotics
Drugs developed by Merck & Co.
Orexin antagonists
Sedatives
Triazoles | Suvorexant | Biology | 8,244 |
63,281,547 | https://en.wikipedia.org/wiki/HH%2024-26 | HH 24-26 is a molecular cloud and star-forming region containing the Herbig-Haro objects HH 24, HH 25 and HH 26. This region contains the highest concentration of astrophysical jets known anywhere in the sky. The molecular cloud is located about 1400 light-years away in the L1630 dark cloud, which is part of the Orion B molecular cloud in the constellation of Orion.
The region contains multiple protostars (two class 0 and one class I) and four more evolved IRAS sources. The three protostars are driving the Herbig-Haro objects in this region.
Observation
The L1630 dark cloud also contains NGC 2071 and the Flame Nebula. HH 24-26 is located just a few arcminutes south of Messier 78.
HH 24
The image of HH 24 taken by the Hubble Space Telescope is probably the most well known image of this Herbig-Haro object. HH 24 resembles a lightsaber from the science fiction movies Star Wars and the Hubble image was published during the release of Star Wars Episode VII: The Force Awakens.
HH 24 contains a class 0 protostar, which might be a proto-binary system. The disks around these objects are highly misaligned, which is a sign of turbulent fragmentation.
See also
Astronomy Picture of the Day
References
External links
APOD: 2014 February 4 - A Particle Beam Jet forms HH 24
APOD: 2015 December 18 - Herbig-Haro 24
APOD: 2018 March 11 - Dual Particle Beams in Herbig-Haro 24
Herbig–Haro objects
Orion (constellation)
Orion molecular cloud complex
Reflection nebulae
Molecular clouds | HH 24-26 | Astronomy | 345 |
7,685,023 | https://en.wikipedia.org/wiki/CLHEP | CLHEP (short for A Class Library for High Energy Physics) is a C++ library that provides utility classes for general numerical programming, vector arithmetic, geometry, pseudorandom number generation, and linear algebra, specifically targeted for high energy physics simulation and analysis software.
The project is hosted by CERN and currently managed by a collaboration of researchers from CERN and other physics research laboratories and academic institutions. According to the project's website, CLHEP is in maintenance mode (accepting bug fixes but no further development is expected).
CLHEP was proposed by Swedish physicist Leif Lönnblad in 1992 at a Conference on Computing in High-Energy Physics. Lönnblad is still involved in maintaining CLHEP.
The project has more recently accepted contributions from other projects built on top of CLHEP, including the physics packages Geant4 and ZOOM, and the BaBar experiment at SLAC.
See also
Geant4, a software using CLHEP
FreeHEP, a similar library to CLHEP
COLT, a Java package for High Performance Scientific and Technical Computing, provided by CERN.
References
External links
Project CLHEP website
CLHEP User Guide
CLHEP at CERN
Physics software
CERN software | CLHEP | Physics | 254 |
70,175,623 | https://en.wikipedia.org/wiki/K-stability%20of%20Fano%20varieties | In mathematics, and in particular algebraic geometry, K-stability is an algebro-geometric stability condition for projective algebraic varieties and complex manifolds. K-stability is of particular importance for the case of Fano varieties, where it is the correct stability condition to allow the formation of moduli spaces, and where it precisely characterises the existence of Kähler–Einstein metrics.
The first attempt to define K-stability for Fano manifolds was made by Gang Tian in 1997, in response to a conjecture of Shing-Tung Yau from 1993 that there should exist a stability condition which characterises the existence of a Kähler–Einstein metric on a Fano manifold. It was defined in reference to the K-energy functional previously introduced by Toshiki Mabuchi. Tian's definition of K-stability was later replaced
by a purely algebro-geometric refinement that was first formulated by Simon Donaldson in 2001.
K-stability has become an important notion in the study and classification of Fano varieties. In 2012 Xiuxiong Chen, Donaldson, and Song Sun proved that a smooth Fano manifold is K-polystable if and only if it admits a Kähler–Einstein metric. (Tian then announced a nearly identical proof, under circumstances that resulted in a bitter priority dispute.) This theorem was later generalised to singular K-polystable Fano varieties due to the work of Berman–Boucksom–Jonsson and others. K-stability is important in constructing moduli spaces of Fano varieties, where observations going back to the original development of geometric invariant theory show that it is necessary to restrict to a class of stable objects to form good moduli. It is now known through the work of Chenyang Xu and others that there exists a projective coarse moduli space of K-polystable Fano varieties of finite type. This work relies on Caucher Birkar's proof of boundedness of Fano varieties, for which he was awarded the 2018 Fields medal. Due to the reformulations of the K-stability condition by Fujita–Li and Odaka, the K-stability of Fano varieties may be explicitly computed in practice. Which Fano varieties are K-stable is well understood in dimension one, two, and three.
Definition and characterisations
The notion of K-stability for Fano manifolds was originally specified using differential geometry by Tian, who extended the purely analytical notion of the Futaki invariant of a vector field to the case of certain normal varieties with orbifold singularities. This was later reformulated in a purely algebro-geometric form by Donaldson, but this general definition lost a direct link to the geometry of Fano varieties, instead making sense for the broader class of all projective varieties. Work of Tian shows that the Donaldson–Futaki invariant specifying the weight of the -action on the central fibre of a test configuration can be computed in terms of certain intersection numbers (corresponding to the weight of an action on the so-called CM line bundle). In the Fano case these intersection numbers, which involve the anticanonical divisor of the variety and its test configuration, can be given powerful alternative characterisations in terms of the algebraic and birational geometry of the Fano variety.
Thus in the case of Fano varieties, there are many different but equivalent characterisations of K-stability, and some of these characterisations lend themselves to explicit calculation or easier proofs of results.
In this section all definitions are stated in the generality of a -Fano variety, which is a Fano variety with ample -Cartier anticanonical divisor and at worst Kawamata log terminal (klt) singularities. The definitions of K-stability can be made for any -Gorenstein Fano variety (that is, any Fano variety where the anticanonical divisor is -Cartier), however it was proven by Odaka that every K-semistable Fano variety has at worst klt singularities, so for the purpose of studying K-stability it suffices to assume at worst klt singularities. Every definition can be extended in a straightforward way to -log Fano pairs, a pair of a klt variety X and klt divisor such that is ample and -Cartier.
Traditional definition
The definition of K-stability for a Fano manifold, or more generally a -Fano variety, can be given in many forms. The general definition of K-stability in terms of test configurations (see K-stability for more details) can be simplified if the type of test configuration one considers can be simplified. For example, in the case of toric varieties, one may always take test configurations which are also toric, and this leads to a recharacterisation of K-stability in terms of convex functions on the moment polytope of the toric variety, as was observed by Donaldson in his first paper on K-stability.
In the case of Fano manifolds, it was already implicit in the work of Tian that one may restrict to test configurations with a simplified central fibre, in that case where the central fibre is a normal variety.
In this case there exists an intersection-theoretic formula for the Donaldson–Futaki invariant of a normal test configuration for . Explicitly, one extends the test configuration to a test configuration over the complex projective line trivially at the point , one has a formula
With respect to this invariant, if is a -Fano variety, we say is
K-semistable if for any normal test configuration .
K-stable if for any normal test configuration which is not isomorphic to the trivial test configuration outside a set of codimension 2.
Uniformly K-stable if for any normal test configuration , where is the minimum norm of the test configuration and is a uniform constant depending only on .
K-unstable if is not K-semistable.
According to the above definitions, there are implications
Uniformly K-stable K-stable K-semistable
The above definitions are not well-suited to the situation where the Fano variety has automorphisms. When the space of automorphisms is positive-dimensional , it was observed by Akito Futaki that there are certain test configurations constructed out of the automorphisms of which are "trivial" for the perspective of testing K-stability. In this case one should restrict to those test configurations which are equivariant with respect to the action of a maximal torus , and this leads to the notion of K-polystability or reduced K-stability. We say is
K-polystable if for any test configuration and equality holds precisely when is isomorphic to outside a set of codimension 2.
Reduced uniformly K-stable if where is the reduced -norm of the test configuration.
As for the case where the automorphism group is not positive-dimensional, we have implications
Reduced uniformly K-stable K-polystable K-semistable
The condition of uniform stability is a priori stronger than stability, because it assumes a uniform bound above zero for the Donaldson–Futaki invariant of the test configuration. However it turns out in the case of -Fano varieties uniform stability is actually equivalent to stability.
Many results can be proved more easily for uniform K-stability because a uniform bound is stronger than a non-uniform bound, so often one works with this definition as opposed to the traditional K-(poly)stability. In the more general case of a polarised variety considered in the article on K-stability it is still an open and important problem to characterise how (reduced) uniform K-stability relates to K-(poly)stability.
Special test configurations
As mentioned above, sometimes the type of test configuration to be considered can be simplified. In the case of Fano varieties, a special test configuration is a test configuration such that we have a rational equivalence of divisors for some , and the central fibre is also a -Fano variety.
One may prove that given any test configuration , there exists a special test configuration such that
This implies that for the purposes of testing the K-stability of , it suffices restrict to just looking at the above definitions of K-stability for special test configurations. The fact that one may assume the central fibre of the test configuration is also Fano leads to strong links with birational geometry and the minimal model program, providing a number of alternative characterisations of K-stability described in the following sections.
The main alternative characterisation is in terms of a different notion of Ding stability, which is a variation of the K-stability condition for the Ding invariant
where one adds on the log canonical threshold of the test configuration. The Ding invariant can only be defined in the setting of Fano varieties. Using this new invariant instead of , one can define every notion of Ding stability exactly as above, leading to Ding (semi/poly)stability and uniform versions. The Ding invariant has better formal properties with respect to algebraic geometry than the Donaldson–Futaki invariant. It is known that when a test configuration is special, the Ding invariant agrees with the Donaldson–Futaki invariant up to a constant factor, and so for Fano varieties Ding stability is equivalent to K-stability.
Alpha invariant
The first known effective criteria to test for K-stability was developed by Tian. Originally Tian's work was designed to directly provide a criterion for the existence of a Kähler–Einstein metric on a Fano manifold, and by later work it is known that every Kähler–Einstein Fano manifold is K-polystable. Tian's original definition of the alpha invariant was analytical in nature, but can be used to verify the existence of a Kähler–Einstein metric in practice.
The alpha invariant of Tian can be defined relative to a group of automorphisms , and the alpha invariant corresponds to the concept of reduced K-stability or K-polystability above. Fix a -invariant Kähler metric on a Fano manifold. Define a special class of Kähler potentials by
Then the alpha invariant is defined by
The importance of this invariant is as follows:
It was later observed by Odaka–Sano that the alpha invariant can be given a purely algebro-geometric definition in terms of an infimum of the log canonical threshold over all -invariant linear systems contained inside . Precisely, Demailly showed This allows purely algebro-geometric proofs of the existence of Kähler–Einstein metrics.
Beta invariant
The beta invariant makes close contact with birational geometry. This invariant was developed by Fujita and Li in an attempt to discover a characterisation of K-stability in terms of divisors or valuations of the Fano variety . This work was inspired by earlier ideas of Ross–Thomas which attempted to describe K-stability in terms of algebraic invariants coming out of subschemes of the variety . Whilst it is not possible to show that this "slope" K-stability is equivalent to K-stability, by passing not just to divisors inside but divisors inside any birational model over , one obtains "enough" objects to accurately test for K-stability.
In particular Fujita realised that Ross–Thomas's notion of slope K-stability was limited by only integrating up to the Seshadri constant of the subscheme, where the natural divisor on the blow-up becomes ample. By contract the -invariant integrates up to the pseudoeffective threshold where the natural divisor has positive volume (since every ample divisor has positive volume, the pseudoeffective threshold goes beyond the Seshadri constant). This extra information gives Fujita and Li's valuative criterion enough information to fully characterise K-stability.
Suppose is a normal variety with -Cartier canonical divisor . One says is a divisor over if is a divisor contained inside some normal variety such that there exists a proper birational morphism (for example given by a blow up of ). One defines the log discrepancy of a divisor over as
where is the discrepancy of the divisor in the sense of birational geometry (see canonical singularity). The discrepancy of a divisor over is defined as follows. Away from the exceptional locus of the birational morphism , the canonical divisors of and agree. Therefore, their difference is given by some sum of prime divisors contained in the exceptional locus of . That is,
where . By definition and when is not one of the prime divisors in the exceptional locus. The log discrepancy of measures the singularities of the Fano variety. In particular X is Kawamata log terminal if and only if for any over .
To define the beta invariant, one also needs the a volume term. For a divisor over , define
Here the volume of a divisor measures the rate at which its space of sections grows in comparison to the expected dimension. Namely,
where .
Finally, the beta invariant was defined by Fujita and Li as
Despite the complicated definition, due to the powerful tools of birational geometry, this invariant may be explicitly computed in practice for many classes of Fano varieties where the structure of divisors in their birational models is known. This can often be achieved with the use of computational algebraic geometry or by-hand calculation.
The relevance of the -invariant is in the following characterisation of K-stability first observed (in one direction) by Fujita and Li independently.
Delta invariant
The delta invariant can be defined as a "multiplicative" version of the "additive" beta invariant. The delta invariant of a divisor over is defined by
The delta invariant of is then given by a uniform measurement of the delta invariants of all divisors over .
The delta invariant of a divisor is conceptually similar to the beta invariant, however it was observed by Fujita–Odaka that one can compute the delta invariant as a limit of "quantized" delta invariants as . The quantized delta invariants can be computed in terms of m-basis type divisors which are given by choices of bases in the fixed finite-dimensional vector space . Thus the delta invariant is generally more computable and more theoretically powerful than its predecessors, and much progress on the explicit computations of K-stability for Fano varieties, and in the theory of moduli of Fano varieties has occurred since its introduction.
Its initial importance to the theory of K-stability is captured in the following characterisation.
The algebraic -invariant can make contact with the explicit analytical properties of Kähler–Einstein metrics. In particular, one may define the greatest Ricci lower bound as the supremum of all such that there exists a Kähler metric such that . This is the limit of how far one can traverse the natural continuity method to solve the Kähler–Einstein equation. If the greatest Ricci lower bound takes the value then one can complete the continuity method to derive the existence of a Kähler–Einstein metric. It turns out that precisely how far you can go along this continuity method, the greatest Ricci lower bound, is exactly given by the -invariant. That is,
In the case of toric Fano manifolds an even more geometric interpretation of the delta invariant was derived by Li. For such a toric Fano , the origin is always contained in the interior of the moment polytope . If denotes the barycentre of the polytope and denotes the point on the boundary of the polytope intersecting the ray , then Li showed that the greatest Ricci lower bound is given by the ratio . In particular the toric Fano has if and only if its barycentre is the origin. Interpreted using the delta invariant (and indeed using earlier results), one concludes that a toric Fano manifold is K-stable if and only if the barycentre of its polytope is the origin.
Existence of Kähler–Einstein metrics
From its initial introduction, the notion of K-stability has been intimately linked to the existence of Kähler–Einstein metrics on Fano manifolds. There are now many theorems which relate certain K-stability assumptions to the existence of solutions. These conjectures fall broadly under the title of the Yau–Tian–Donaldson conjecture. In the case of Fano varieties this conjecture asserts:For Fano manifolds this conjecture was originally proposed by Yau and Tian, and a more general form was stated by Donaldson which extends beyond just the case of Fano manifolds. Nevertheless, the conjecture even in the case of Fanos has come to be known as the Yau–Tian–Donaldson conjecture. See K-stability for more discussion of the general conjecture.
In the case of Fano manifolds, the YTD conjecture admits generalisations beyond the case of smooth varieties and forms of the conjecture are now known for singular Fanos and log Fanos.
Smooth Fano varieties
The forward direction of the conjecture, that a Fano manifold with a Kähler–Einstein metric is K-polystable, was proven by Tian in his original paper when the Fano manifold has a discrete automorphism group, that is, . This direction was proven in full generality, removing the assumption that the automorphism group was discrete, by Berman.
The reverse direction of the Yau–Tian–Donaldson conjecture was first resolved in the smooth case as stated above by Chen–Donaldson–Sun, and at the same time by Tian. Chen, Donaldson, and Sun have alleged that Tian's claim to equal priority for the proof is incorrect, and they have accused him of academic misconduct. Tian has disputed their claims. Chen, Donaldson, and Sun were recognized by the American Mathematical Society's prestigious 2019 Veblen Prize as having had resolved the conjecture. The Breakthrough Prize has recognized Donaldson with the Breakthrough Prize in Mathematics and Sun with the New Horizons Breakthrough Prize, in part based upon their work with Chen on the conjecture.The proofs of Chen–Donaldson–Sun and Tian were based on a delicate study of Gromov–Hausdorff limits of Fano manifolds with Ricci curvature bounds. More recently, a proof based on the "classical" continuity method was provided by Ved Datar and Gabor Székelyhidi, followed by a proof by Chen, Sun, and Bing Wang using the Kähler–Ricci flow.
Robert Berman, Sébastien Boucksom, and Mattias Jonsson also provided a proof from a new variational approach, which interprets K-stability in terms of Non-Archimedean geometry. Of particular interest is that the proof of Berman–Boucksom–Jonsson also applies to the case of a smooth log Fano pair, and does not use the notion of K-polystability but of uniform K-stability as introduced by Dervan and Boucksom–Hisamoto–Jonsson. It is now known that uniform K-stability is equivalent to K-stability and so BBJ's proof provides a new proof of the full YTD conjecture.
Building on the variational techniques Berman–Boucksom–Jonsson and the so-called quantized delta invariants of Fujita–Odaka, Zhang produced a short quantization-based proof of the YTD conjecture for smooth Fano manifolds.
Using other techniques entirely, Berman has also produced a proof of a YTD-type conjecture using a thermodynamic approach called uniform Gibbs stability, where a Kähler–Einstein metric is constructed through a random point process.
Singular Fano varieties and weak Kähler–Einstein metrics
The new proof of the Yau–Tian–Donaldson conjecture by Berman–Boucksom–Jonsson using variational techniques opened up the possible study of K-stability and Kähler–Einstein metrics for singular Fano varieties. The variational techniques used rely on uniform K-stability as described above.
The result of Berman that a Fano manifold admitting a Kähler–Einstein metric is K-polystable was proven in the full generality of a -log Fano pair, admitting a weak Kähler–Einstein metric. A weak Kähler–Einstein metric on a -Fano variety is a positive -current which restricts to give a smooth Kähler–Einstein metric on the smooth locus of . By requiring a compatibility with a divisor , this definition can be extended to a weak Kähler–Einstein metric on a pair .
In this generality, the reverse direction of the YTD conjecture was proven by Li–Tian–Wang in the case where the automorphism group is discrete, and in full generality by Li.By the resolution of the finite generation conjecture by Liu–Xu–Zhuang it is known that reduced uniform K-stability is equivalent to K-polystability, so combined with Berman's result the Yau–Tian–Donaldson conjecture is true in complete generality for singular Fano varieties.
Moduli spaces of K-stable Fano varieties
The construction of moduli spaces is a central problem in algebraic geometry. The construction of moduli of algebraic curves spurred the development of geometric invariant theory, stacks, and classification of algebraic surfaces has motivated results throughout algebraic geometry. The case of moduli spaces of canonically polarised varieties was settled using techniques arising from the minimal model program by Kollár–Shepherd-Barron leading to the so-called KSB moduli spaces of varieties of general type. A key property of varieties of general type which allow the construction of moduli is the lack of automorphisms of such varieties. This does not hold for Fano varieties, which can often have very large automorphism groups, so the minimal model program did not directly find applications to the construction of moduli of Fano varieties, and it became clear that K-stability was the correct algebro-geometric notion to allow the formation of moduli in this case. Moduli spaces of K-stable varieties are known as K-moduli.
Smooth case
In the case of smooth Fano manifolds, one may use techniques arising out of the Yau–Tian–Donaldson conjecture to construct the moduli space analytically. In particular work of Odaka and Donaldson building upon the ideas of Gromov compactness of Kähler–Einstein Fanos used in the proof of the YTD conjecture implies the existence of moduli spaces of smooth Fano Kähler–Einstein manifolds with discrete automorphism groups. These moduli spaces are Hausdorff and have at worst quotient singularities. By the YTD conjecture these are alternatively moduli spaces of smooth K-polystable Fano varieties with discrete automorphism groups. However, a Gromov–Hausdorff limit of smooth Fano Kähler–Einstein manifolds may lead to a singular -Fano variety, so the moduli spaces described by Odaka and Donaldson is not compact, a criterion that is often desirable in the formation of moduli spaces. One method of compactifying the moduli space of smooth K-polystable Fanos is to pass to a moduli space of singular K-polystable Fanos, and use algebraic geometry to prove its projectivity. The Yau–Tian–Donaldson conjecture for singular Fano varieties would give this compactification an alternative point of view as consisting of singular Fano varieties with weak Kähler–Einstein metrics.
General case
The standard algebraic technique to construct moduli spaces utilizes geometric invariant theory. Typically to apply Mumford's geometric invariant theory to construct moduli, one must embed a family of varieties inside a fixed finite-dimensional projective space. Such a family then defines a locus of points in the corresponding Hilbert scheme of the projective space, which is a projective scheme on which the group of projective automorphisms act. GIT stability with respect to this linearisation is called Hilbert stability. If this locus forms an open set, then GIT may be used to construct a quotient which parametrises these objects. In good circumstances this quotient may be proper and projective.
It is not always possible to embed a family of varieties inside a fixed projective space and therefore describe their moduli with geometric invariant theory, and this special property is called boundedness. A fundamental property of Fano varieties is that they fail to be bounded, and thus their stability cannot be reasonably captured by any finite-dimensional geometric invariant theory. This explains why K-stability requires one to consider test configurations for which the relatively ample line bundle can correspond to some power for arbitrarily large. However, results of Caucher Birkar showed that certain families of Fano varieties with volume bounded below form bounded families, which suggests that it may be possible to study stability of volume-bounded families of Fano varieties to form moduli spaces. For this work Birkar was awarded the Fields Medal in 2018.
It was proven by Jiang that K-semistable -Fano varieties with volume bounded below form a bounded family. Thus for a given volume there exists a uniform integer such that every K-semistable -Fano with anticanonical volume larger than or equal to admits an embedding inside the fixed projective space . The openness of this locus of K-semistable Fanos was proven by Blum–Liu–Xu and Xu. This implies the existence of an Artin stack of finite type denoted parametrising K-semistable -Fano varieties with volume bounded below by .
In order to find a genuine moduli space as a projective variety or scheme, one must prove certain properties about S-completeness and -reductivity of K-semistable Fanos inside the stack . Using properties of K-polystability, these properties of the moduli stack are true and there exists a coarse moduli space for the stack which parametrises K-polystable -Fano varieties with volume bounded below by . It was proven that is proper and that the CM-line bundle is ample, meaning the coarse moduli space is also projective. The existence result for K-moduli can be summarised in the following theorem.The construction of the moduli space of K-polystable Fanos can be generalised to the setting of log Fano varieties. The case of singular -Fano varieties which are smoothable (that is they are limits of algebraic families of smooth K-polystable Fano manifolds) was solved earlier by Li–Wang–Xu using a combination of analytic techniques, also relying on the earlier work of Odaka, Donaldson, and Codogni–Patakfalvi. There the coarse moduli space is shown to be a scheme, but in general the existence results for K-moduli only guarantee the existence of an algebraic space.
Explicit K-stability of Fano varieties
The explicit study of K-stable Fano varieties precedes the algebraic notion of K-stability, and in low dimensions was of interest purely due to the study of Kähler–Einstein manifolds. For example, either by explicit construction or the use the Tian's alpha invariant, all smooth Kähler–Einstein manifolds of dimension 1 and 2 were known before the definition of K-stability was introduced. In dimension 3 and higher explicit constructions of Kähler–Einstein metrics become more difficult, but advances arising out of the algebraic study of K-stability have enabled explicit computations of K-polystable Fano threefolds and certain families of higher dimensional varieties, and subsequently the discovery of new Kähler–Einstein manifolds.
Dimension 1
In dimension one there is a unique smooth Fano variety, the complex projective line . This variety is easily seen to be K-stable due to the existence of the Fubini–Study metric, which is a Kähler–Einstein metric, implying the K-polystability of .
A purely algebro-geometric proof of the K-stability of smooth Riemann surfaces follows from the work of Ross–Thomas on slope K-stability, which is equivalent to K-stability in dimension one. In this case one may construct test configurations out of collections of points on the curve, and when the curve is smooth no points destabilise.
Dimension 2
In dimension two the spaces which admit Kähler–Einstein metrics were classified by Tian. There are 10 deformation families of smooth Fano varieties in dimension two, the del Pezzo surfaces. Using the alpha invariant, Tian showed that a smooth Fano surface admits a Kähler–Einstein metric and is K-polystable if and only if it is not the blow up of the complex projective plane in one or two points. Thus 8 out of these 10 classes consist of K-polystable Fano surfaces.
The K-moduli of Fano surfaces were studied in explicit examples by Tian and Mabuchi–Mukai. Explicit constructions of compact moduli spaces of Kähler–Einstein Fano surfaces were achieved by Odaka–Spotti–Sun. These spaces were constructed as Gromov–Hausdorff compactifications but were identified with explicit algebraic spaces of log Fano surfaces.
For example, it is proven by Odaka–Spotti–Sun that the compact moduli space of smoothable Kähler–Einstein surfaces of degree four is given by the weighted projective space with the smooth Kähler–Einstein surfaces of degree four corresponding to the locus where is an ample divisor consisting of those points satisfying the equation .
Dimension 3
In dimension 3 purely algebraic techniques can be used to find examples of K-stable Fano varieties which are not a priori known to admit Kähler–Einstein metrics. The Iskovskikh–Mori–Mukai classification of smooth Fano threefolds provides a natural way of breaking down the problem of studying K-stable Fano threefolds into its components. It is known that there are 105 deformation families of smooth Fano threefolds, and explicit computations using Fujita–Li's beta invariant and Fujita–Odaka's delta invariant can be used to determine which deformation families contain K-stable representatives.
For every deformation family it is known whether the generic element of the family is K-(poly)stable. In particular it is known that 78 out of 105 families contain a K-polystable representative in their deformation class. For 71 out of 105 families, it is known for every single member of the deformation class whether or not it is K-polystable. For many examples of the 105 deformation families, the K-stability of representative threefolds can be interpreted in terms of a natural GIT problem which describes that family, and so explicit examples of K-moduli of Fano threefolds can also be found as GIT quotients.
For some classes of Fano threefolds the classification problem remains open. For example, it is known that the Mukai–Umemura threefold in the deformation class admits a Kähler–Einstein metric and is therefore K-polystable by work of Donaldson, who computed Tian's alpha invariant explicitly using the criterion above. This manifold has non-discrete automorphism group and which nearby deformations of are also K-polystable is not known. It is conjectured that the deformations corresponding to GIT-polystable points within the versal deformation space of should correspond to nearby K-polystable varieties.
Higher dimensions
The first and simplest example of a K-polystable Fano manifold in any dimension is complex projective space, which always admits the Fubini–Study metric which is Kähler–Einstein in any dimension and therefore all projective spaces are K-polystable.
In general there are not many such "obvious" Kähler–Einstein metrics in higher dimensions, and one must use recent techniques of stability to find examples. For certain families of Fano varieties, K-stability can be proved in higher dimensions using either analytic techniques through the alpha invariant or purely algebro-geometric techniques with the beta or delta invariants. As an example, a Fermat hypersurface is a variety of the form
These hypersurfaces are smooth Fano manifolds with discrete automorphism group for , and it was proven by Tian using the alpha invariant that implying admits a Kähler–Einstein for , and using more detailed arguments Tian proved the existence of a Kähler–Einstein metric when . On the other hand, using the delta invariant Zhuang gave a completely algebraic proof that is K-stable for and therefore admits a Kähler–Einstein metric in these cases. Using the openness results for uniform K-stability and K-semistability, one can conclude from this that the generic smooth hypersurface of degree inside is K-stable. In some cases it is in fact known that all degree hypersurfaces are K-stable, such as all smooth hypersurfaces in .
In addition to the study of particular Fano varieties, in certain settings K-moduli may be explicitly described in higher dimensions. For example, when the K-moduli admits an "obvious" GIT interpretation, the algebraic tools of beta or delta invariants can be used to verify that GIT stability is equivalent to K-stability for that particular problem. For example, Liu showed that for cubic fourfold hypersurfaces in , the GIT moduli space of (possibly singular) cubic fourfolds is isomorphic to the K-moduli space, and thus one obtains an explicit description of the K-stable, K-polystable, and K-semistable cubic fourfolds in terms of their GIT stability and singularity structure. In particular every smooth cubic fourfold is K-stable.
References
Notes
Algebraic geometry | K-stability of Fano varieties | Mathematics | 6,936 |
6,678,342 | https://en.wikipedia.org/wiki/Open-circuit%20voltage | Open-circuit voltage (abbreviated as OCV or VOC) is the difference of electrical potential between two terminals of an electronic device when disconnected from any circuit. There is no external load connected. No external electric current flows between the terminals. Alternatively, the open-circuit voltage may be thought of as the voltage that must be applied to a solar cell or a battery to stop the current. It is sometimes given the symbol Voc. In network analysis this voltage is also known as the Thévenin voltage.
The open-circuit voltages of batteries and solar cells are often quoted under particular conditions (state-of-charge, illumination, temperature, etc.).
The potential difference mentioned for batteries and cells is usually the open-circuit voltage.
The value of the open-circuit voltage of a transducer equals its electromotive force (emf), which is the maximum potential difference it can produce when not providing current.
Example
Consider the circuit:
If we want to find the open-circuit voltage across the 5Ω resistor, first disconnect it from the circuit:
Find the equivalent resistance in loop 1 to find the current in loop 1. Use Ohm’s law with that current to find the potential drop across the resistance C. Note that since no current is flowing through resistor B, there is no potential drop across it, so it does not affect the open-circuit voltage.
The open-circuit voltage is the potential drop across the resistance C, which is:
This is just an example. Many other ways can be used.
See also
Electromotive force
Short circuit
Thevenin's Theorem
References
Electrical parameters | Open-circuit voltage | Engineering | 334 |
72,084,320 | https://en.wikipedia.org/wiki/Georgia%20Purdom | Georgia Purdom (née Hickman; born 1972) is an American biologist and Young Earth creationist. She is the director of Educational Content at Answers in Genesis.
Early life
Purdom was born in 1972, and grew up near Columbus, Ohio in what she described as a "very strong Christian home". She attended a Nazarene church.
Education and career
Purdom studied at Cedarville University, graduating in 1994, before going on to get a PhD in molecular genetics from Ohio State University. She was an associate professor of biology at Mount Vernon Nazarene University before joining Answers in Genesis. She received the Alumna of the Year award from Cedarville in 2015.
Views
Purdom believes that whether one holds a "biblical versus secular" worldview determines how one interprets scientific data. She also believes that "available evidence supports and confirms biblical creation."
She is the editor of Galapagos Islands: A Different View (2013) which presents a "Bible-based analysis of the islands." Purdom claims that the Galápagos Islands were formed after the Genesis Flood.
Purdom distinguishes her creationist views with that of intelligent design, which she does not regard as Christian.
Purdom claimed that "mutations don’t cause the gain of novel traits—the gain of genetic information—necessary to change from one kind of organism into another" without providing any evidence for that claim. In fact, there are numerous studies demonstrating exactly such changes, especially supported by phylogenetic studies and genome analyses. For instance, novel morphological features are easily selected for in dog breeding and their genetic basis has been well documented. Many other examples are documented in studies on macro-evolution.
Scientific work
Purdom has published three studies that are indexed in Pubmed, all of which apparently resulted from her thesis work at Ohio State University. All three investigate the role of microphthalmia transcription factor (MITF), a protein that regulates gene expression during osteoclast differentiation. None of this work is directly related to evolutionary biology, although the studies show that they are fully compatible with the evolution of gene regulatory networks.
References
External links
Blog at Answers in Genesis
1972 births
Living people
American Christian Young Earth creationists
Creation scientists
American women geneticists
American geneticists
Cedarville University alumni
Ohio State University alumni
Mount Vernon Nazarene University faculty
Molecular geneticists
American members of the Church of the Nazarene
Scientists from Ohio | Georgia Purdom | Biology | 492 |
40,200,899 | https://en.wikipedia.org/wiki/Sidney%20M.%20Cadwell | Sidney Marsh Cadwell (5 March 1893 – 24 June 1986) noted as discoverer of anti-oxidants for rubber. Cadwell published perhaps the first scientific study of the fatigue behavior of rubber.
Cadwell served as Chairman of the Rubber Division of the American Chemical Society in 1935 and was named the 1956 Charles Goodyear Medalist.
PhD University of Chicago 1917
World War I Captain in the Chemical Warfare Service
1919 joined United States Rubber Company
1966 as director of Institute of Applied Chemistry and Physics at Wayne State University, received the Midgley Award of the ACS Detroit Section
References
External links
Recorded Interview with Dr. Sidney M. Cadwell
Polymer scientists and engineers
U.S. Synthetic Rubber Program
1893 births
1986 deaths | Sidney M. Cadwell | Chemistry,Materials_science | 143 |
1,041,043 | https://en.wikipedia.org/wiki/Nafion | Nafion is a brand name for a sulfonated tetrafluoroethylene based fluoropolymer-copolymer synthesized in 1962 by Dr. Donald J. Connolly at the DuPont Experimental Station in Wilmington Delaware (U.S. Patent 3,282,875). Additional work on the polymer family was performed in the late 1960s by Dr. Walther Grot of DuPont. Nafion is a brand of the Chemours company. It is the first of a class of synthetic polymers with ionic properties that are called ionomers. Nafion's unique ionic properties are a result of incorporating perfluorovinyl ether groups terminated with sulfonate groups onto a tetrafluoroethylene (PTFE) backbone. Nafion has received a considerable amount of attention as a proton conductor for proton exchange membrane (PEM) fuel cells because of its excellent chemical and mechanical stability in the harsh conditions of this application.
The chemical basis of Nafion's ion-conductive properties remain a focus of extensive research. Ion conductivity of Nafion increases with the level of hydration. Exposure of Nafion to a humidified environment or liquid water increases the amount of water molecules associated with each sulfonic acid group. The hydrophilic nature of the ionic groups attract water molecules, which begin to solvate the ionic groups and dissociate the protons from the -SO3H (sulfonic acid) group. The dissociated protons "hop" from one acid site to another through mechanisms facilitated by the water molecules and hydrogen bonding. Upon hydration, Nafion phase-separates at nanometer length scales resulting in formation of an interconnected network of hydrophilic domains which allow movement of water and cations, but the membranes do not conduct electrons and minimally conduct anions due to permselectivity (charge-based exclusion). Nafion can be manufactured with or exchanged to alternate cation forms for different applications (e.g. lithiated for Li-ion batteries) and at different equivalent weights (EWs), alternatively considered as ion-exchange capacities (IECs), to achieve a range of cationic conductivities with trade-offs to other physicochemical properties such as water uptake and swelling.
Nomenclature and molecular weight
Nafion can be produced as both a powder resin and a copolymer. It has various chemical configurations and thus several chemical names in the IUPAC system. Nafion-H, for example, includes the following systematic names:
From Chemical Abstracts: ethanesulfonyl fluoride, 2-[1-[difluoro-[(trifluoroethenyl)oxy]methyl]-1,2,2,2-tetrafluoroethoxy]-1,1,2,2,-tetrafluoro-, with tetrafluoroethylene
acid copolymer
The molecular weight of Nafion is variable due to differences in processing and solution morphology. The structure of a Nafion unit illustrates the variability of the material; for example, the most basic monomer contains chain variation between the ether groups (the z subscript). Conventional methods of determining molecular weight such as light scattering and gel permeation chromatography are not applicable because Nafion is insoluble, although the molecular weight has been estimated at 105–106 Da. Instead, the equivalent weight (EW) and material thickness are used to describe most commercially available membranes. The EW is the number of grams of dry Nafion per mole of sulfonic acid groups when the material is in the acid form. Nafion membranes are commonly categorized in terms of their EW and thickness. For example, Nafion 117 indicates an extrusion-cast membrane with 1100 g/mol EW and 0.007 inches (7 thou) in thickness. In contrast to equivalent weight, conventional ion-exchange resins are usually described in terms of their ion exchange capacity (IEC), which is the multiplicative inverse or reciprocal of the equivalent weight, i.e., IEC = 1000/EW.
Preparation
Nafion derivatives are first synthesized by the copolymerization of tetrafluoroethylene (TFE) (the monomer in Teflon) and a derivative of a perfluoro (alkyl vinyl ether) with sulfonyl acid fluoride. The latter reagent can be prepared by the pyrolysis of its respective oxide or carboxylic acid to give the olefinated structure.
The resulting product is an -SO2F-containing thermoplastic that is extruded into films. Hot aqueous NaOH converts these sulfonyl fluoride (-SO2F) groups into sulfonate groups (-SO3−Na+). This form of Nafion, referred to as the neutral or salt form, is finally converted to the acid form containing the sulfonic acid (-SO3H) groups. Nafion can be dispersed into solution by heating in aqueous alcohol at 250 °C in an autoclave for subsequent casting into thin films or use as polymeric binder in electrodes. By this process, Nafion can be used to generate composite films, coat electrodes, or repair damaged membranes.
Properties
The combination of the stable PTFE backbone with the acidic sulfonic groups gives Nafion its characteristics:
It is highly conductive to cations, making it suitable for many membrane applications.
It resists chemical attack. According to Chemours, only alkali metals (particularly sodium) can degrade Nafion under normal temperatures and pressures.
The PTFE backbone interlaced with the ionic sulfonate groups gives Nafion a high chemical stability temperature (e.g. 190 °C) but a softening point in the range of 85-100 °C give it a moderate operating temperature, e.g. up to 100 °C, with additional challenges in all applications due to the loss of water above 100 °C.
It is a superacid catalyst. The combination of fluorinated backbone, sulfonic acid groups, and the stabilizing effect of the polymer matrix make Nafion a very strong acid, with pKa ~ -6. In this respect Nafion resembles the trifluoromethanesulfonic acid, CF3SO3H, although Nafion is a weaker acid by at least three orders of magnitude.
It is selectively and highly permeable to water.
Its proton conductivity up to 0.2 S/cm depending on temperature, hydration state, thermal history and processing conditions.
The solid phase and the aqueous phase of Nafion are both permeable to gases, which is a drawback for energy conversion devices such as artificial leaves, fuel cells, and water electrolyzers.
Structure/morphology
The morphology of Nafion membranes is a matter of continuing study to allow for greater control of its properties. Other properties such as water management, hydration stability at high temperatures, electro-osmotic drag, as well as the mechanical, thermal, and oxidative stability, are affected by the Nafion structure. A number of models have been proposed for the morphology of Nafion to explain its unique transport properties.
The first model for Nafion, called the cluster-channel or cluster-network model, consisted of an equal distribution of sulfonate ion clusters (also described as 'inverted micelles') with a 40 Å (4 nm) diameter held within a continuous fluorocarbon lattice. Narrow channels about 10 Å (1 nm) in diameter interconnect the clusters, which explains the transport properties.
The difficulty in determining the exact structure of Nafion stems from inconsistent solubility and crystalline structure among its various derivatives. Advanced morphological models have included a core-shell model where the ion-rich core is surrounded by an ion poor shell, a rod model where the sulfonic groups arrange into crystal-like rods, and a sandwich model where the polymer forms two layers whose sulfonic groups attract across an aqueous layer where transport occurs. Consistency between the models include a network of ionic clusters; the models differ in the cluster geometry and distribution. Although no model has yet been determined fully correct, some scientists have demonstrated that as the membrane hydrates, Nafion's morphology transforms from the cluster-channel model to a rod-like model.
A cylindrical-water channel model was also proposed based on simulations of small-angle X-ray scattering data and solid state nuclear magnetic resonance studies. In this model, the sulfonic acid functional groups self-organize into arrays of hydrophilic water channels, each ~ 2.5 nm in diameter, through which small ions can be easily transported. Interspersed between the hydrophilic channels are hydrophobic polymer backbones that provide the observed mechanical stability. Many recent studies, however, favored a phase-separated nanostructure consisting of locally-flat, or ribbon-like, hydrophilic domains based on evidence from direct-imaging studies and more comprehensive analysis of the structure and transport properties.
Applications
Nafion's properties make it suitable for a broad range of applications. Nafion has found use in fuel cells, electrochemical devices, chlor-alkali production, metal-ion recovery, water electrolysis, plating, surface treatment of metals, batteries, sensors, Donnan dialysis cells, drug release, gas drying or humidification, and superacid catalysis for the production of fine chemicals. Nafion is also often cited for theoretical potential (i.e., thus far untested) in a number of fields. With consideration of Nafion's wide functionality, only the most significant will be discussed below.
Chlor-alkali production cell membrane
Chlorine and sodium/potassium hydroxide are among the most produced commodity chemicals in the world. Modern production methods produce Cl2 and NaOH/KOH from the electrolysis of brine using a Nafion membrane between half-cells. Before the use of Nafion, industries used mercury containing sodium amalgam to separate sodium metal from cells or asbestos diaphragms to allow for transfer of sodium ions between half cells; both technologies were developed in the latter half of the 19th century. The disadvantages of these systems is worker safety and environmental concerns associated with mercury and asbestos, economical factors also played a part, and in the diaphragm process chloride contamination of the hydroxide product. Nafion was the direct result of the chlor-alkali industry addressing these concerns; Nafion could tolerate the high temperatures, high electrical currents, and corrosive environment of the electrolytic cells.
The figure to the right shows a chlor-alkali cell where Nafion functions as a membrane between half cells. The membrane allows sodium ions to transfer from one cell to the other with minimal electrical resistance. The membrane was also reinforced with additional membranes to prevent gas product mixing and minimize back transfer of Cl− and −OH ions.
Proton exchange membrane (PEM) for fuel cells
Although fuel cells have been used since the 1960s as power supplies for satellites, recently they have received renewed attention for their potential to efficiently produce clean energy from hydrogen. Nafion was found effective as a membrane for proton exchange membrane (PEM) fuel cells by permitting hydrogen ion transport while preventing electron conduction. Solid Polymer Electrolytes, which are made by connecting or depositing electrodes (usually noble metal) to both sides of the membrane, conduct the electrons through an energy requiring process and rejoin the hydrogen ions to react with oxygen and produce water. Fuel cells are expected to find strong use in the transportation industry.
Superacid catalyst for fine chemical production
Nafion, as a superacid, has potential as a catalyst for organic synthesis. Studies have demonstrated catalytic properties in alkylation, isomerization, oligomerization, acylation, ketalization, esterification, hydrolysis of sugars and ethers, and oxidation. New applications are constantly being discovered. These processes, however, have not yet found strong commercial use. Several examples are shown below:
Alkylation with alkyl halides
Nafion-H gives efficient conversion whereas the alternative method, which employs Friedel-Crafts synthesis, can promote polyalkylation:
Acylation
The amount of Nafion-H needed to catalyze the acylation of benzene with aroyl chloride is 10–30% less than the Friedel-Crafts catalyst:
Catalysis of protection groups
Nafion-H increases reaction rates of protection via dihydropyran or o-trialkylsilation of alcohols, phenol, and carboxylic acids.
Isomerization
Nafion can catalyze a 1,2-hydride shift.
It is possible to immobilize enzymes within the Nafion by enlarging pores with lipophilic salts. Nafion maintains a structure and pH to provide a stable environment for the enzymes. Applications include catalytic oxidation of adenine dinucleotides.
Sensors
Nafion has found use in the production of sensors, with application in ion-selective, metallized, optical, and biosensors. What makes Nafion especially interesting is its demonstration in biocompatibility. Nafion has been shown to be stable in cell cultures as well as the human body, and there is considerable research towards the production of higher sensitivity glucose sensors.
Antimicrobial surfaces
Nafion surfaces show an exclusion zone against bacteria colonization. Moreover, layer-by-layer coatings comprising Nafion show excellent antimicrobial properties.
Dehumidification in spacecraft
The SpaceX Dragon 2 human-rated spacecraft uses Nafion membranes to dehumidify the cabin air. One side of the membrane is exposed to the cabin atmosphere, the other to the vacuum of space. This results in dehumidification since Nafion is permeable to water molecules but not air. This saves power and complexity since cooling is not required (as needed with a condensing dehumidifier), and the removed water is rejected to space with no additional mechanism needed.
Modified Nafion for PEM fuel cells
Normal Nafion will dehydrate (thus lose proton conductivity) when the temperature is above ~80 °C. This limitation troubles the design of fuel cells because higher temperatures are desirable for better efficiency and CO tolerance of the platinum catalyst. Silica and zirconium phosphate can be incorporated into Nafion water channels through in situ chemical reactions to increase the working temperature to above 100 °C.
References
External links
What Nafion Membrane is Right for an Electrolyzer / Hydrogen Generation?
Homepage of Walther G. Grot
Walther G. Grot: "Fluorinated Ionomers"
Isotopic effects on Nafion conductivity
Membrane thickness on conductivity_of_Nafion
Nafion hydration
Plastics
Fluoropolymers
Polyelectrolytes
DuPont products
Membrane technology | Nafion | Physics,Chemistry | 3,148 |
23,534,087 | https://en.wikipedia.org/wiki/CommuniGate%20Pro | CommuniGate Pro (CGatePro) is a highly scalable carrier grade unified communications server, as well as a development platform. The system is Internet Protocol based. The server is a single process, multi-threaded application written entirely in C++. APIs are available for authentication, helper applications and directory services.
Features
CommuniGate Pro provides web interface (with context-insensitive online help facilities) for configuration of its services. Since version 5 custom procedural CG/PL scripting language is provided for performing advanced configuration tasks, including modification of or integration with software's modules. Perl, Java and command line interface-based application programming interfaces are also available.
CommuniGate Pro integrates with Microsoft Outlook via bundled Messaging Application Programming Interface and ActiveSync connectors. Support for other personal information managers, including Apple Inc.'s iCal, is also available. Communications between connectors and server may be encrypted using Secure Sockets Layer (SSL) or Transport Layer Security (TLS) cryptographic protocols.
Email
CommuniGate Pro includes mail transfer agent (MTA) protocols that support POP3, IMAP4 and SMTP (along with their secure variations), as well as webmail interface. Apart from standard genre-defined functionality, it is capable of subscribing users to several mailboxes and advanced mail filtering (including calling arbitrary external software, e.g. SpamAssassin for anti-spam protection). Anti-virus protection is available via extra modules, sold separately.
Collaboration
Since version 5 CommuniGate Pro includes Session Initiation Protocol (SIP) server, which provides instant messaging and voice and video conferencing along with custom Windows Messenger-compatible collaboration-oriented extensions for presence sharing, whiteboarding, and screen and file sharing.
Starting with version 5.1 CommuniGate Pro includes its own XML Interface to Messaging, Scheduling, and Signaling (XIMSS) protocol together with the webmail "Pronto !" client for this protocol. XIMSS offers HTTP- and XML-based client interface to a complex of communications services provided by one server. Although the protocol is not bound to CommuniGate Pro, its scope is derived from the parent project's functionality; so far no other XIMSS servers were announced.
Since version 5.1 Extensible Messaging and Presence Protocol (XMPP) is also supported.
Distribution model
CommuniGate Pro is available as a free download, although after adding more than five users, it adds a one-line banner to the outbound messages. The list of supported platforms include Linux, FreeBSD, Linux, macOS, Solaris, AIX, and Microsoft Windows. Communigate Pro previously supported a wide variety of additional platforms, including OS/400, OpenVMS, Tru64, HP-UX and UnixWare.
Connecters may be installed onto clients directly from deployed server and support automatic update feature.
Reception
In their generally positive reviews, Wendy M. Grossman of ZDNet, Aaron Weiss of ServerWatch and Michael Caton of eWeek praised CommuniGate Pro for its scalability, set of features and high configurability, while criticising it for high price and complexity. Aaron Weiss notes: "CommuniGate Pro is extremely configurable. It wants to be configured. It begs for it. This is a hard-core enterprise server product likely to intimidate point-and-click administrators but happily curl every tech monkey's tail."
Criminal case
The programmer who developed CommuniGate Pro, Vladimir Butenko, died in 2018. Authorship and exclusive rights were registered in the USA, and in 2015 a certificate from Rospatent was added to them. In 2021, his daughter Anna Butenko filed a statement with the prosecutor’s office, accusing the management of the program owner, StalkerSoft, of copyright theft. In 2022, three top managers were indicted. In January 2024, the court stopped hearings on this case and returned it to the prosecutor's office for revision.
See also
Comparison of mail servers
List of mail server software
References
Groupware
Instant messaging server software
Message transfer agents
Web conferencing | CommuniGate Pro | Technology | 858 |
7,333,367 | https://en.wikipedia.org/wiki/Industrial%20control%20system | An industrial control system (ICS) is an electronic control system and associated instrumentation used for industrial process control. Control systems can range in size from a few modular panel-mounted controllers to large interconnected and interactive distributed control systems (DCSs) with many thousands of field connections. Control systems receive data from remote sensors measuring process variables (PVs), compare the collected data with desired setpoints (SPs), and derive command functions that are used to control a process through the final control elements (FCEs), such as control valves.
Larger systems are usually implemented by supervisory control and data acquisition (SCADA) systems, or DCSs, and programmable logic controllers (PLCs), though SCADA and PLC systems are scalable down to small systems with few control loops. Such systems are extensively used in industries such as chemical processing, pulp and paper manufacture, power generation, oil and gas processing, and telecommunications.
Discrete controllers
The simplest control systems are based around small discrete controllers with a single control loop each. These are usually panel mounted which allows direct viewing of the front panel and provides means of manual intervention by the operator, either to manually control the process or to change control setpoints. Originally these would be pneumatic controllers, a few of which are still in use, but nearly all are now electronic.
Quite complex systems can be created with networks of these controllers communicating using industry-standard protocols. Networking allows the use of local or remote SCADA operator interfaces, and enables the cascading and interlocking of controllers. However, as the number of control loops increase for a system design there is a point where the use of a programmable logic controller (PLC) or distributed control system (DCS) is more manageable or cost-effective.
Distributed control systems
A distributed control system (DCS) is a digital process control system (PCS) for a process or plant, wherein controller functions and field connection modules are distributed throughout the system. As the number of control loops grows, DCS becomes more cost effective than discrete controllers. Additionally, a DCS provides supervisory viewing and management over large industrial processes. In a DCS, a hierarchy of controllers is connected by communication networks, allowing centralized control rooms and local on-plant monitoring and control.
A DCS enables easy configuration of plant controls such as cascaded loops and interlocks, and easy interfacing with other computer systems such as production control. It also enables more sophisticated alarm handling, introduces automatic event logging, removes the need for physical records such as chart recorders and allows the control equipment to be networked and thereby located locally to the equipment being controlled to reduce cabling.
A DCS typically uses custom-designed processors as controllers and uses either proprietary interconnections or standard protocols for communication. Input and output modules form the peripheral components of the system.
The processors receive information from input modules, process the information and decide control actions to be performed by the output modules. The input modules receive information from sensing instruments in the process (or field) and the output modules transmit instructions to the final control elements, such as control valves.
The field inputs and outputs can either be continuously changing analog signals e.g. current loop or 2 state signals that switch either on or off, such as relay contacts or a semiconductor switch.
Distributed control systems can normally also support Foundation Fieldbus, PROFIBUS, HART, Modbus and other digital communication buses that carry not only input and output signals but also advanced messages such as error diagnostics and status signals.
SCADA systems
Supervisory control and data acquisition (SCADA) is a control system architecture that uses computers, networked data communications and graphical user interfaces for high-level process supervisory management. The operator interfaces which enable monitoring and the issuing of process commands, such as controller setpoint changes, are handled through the SCADA supervisory computer system. However, the real-time control logic or controller calculations are performed by networked modules which connect to other peripheral devices such as programmable logic controllers and discrete PID controllers which interface to the process plant or machinery.
The SCADA concept was developed as a universal means of remote access to a variety of local control modules, which could be from different manufacturers allowing access through standard automation protocols. In practice, large SCADA systems have grown to become very similar to distributed control systems in function, but using multiple means of interfacing with the plant. They can control large-scale processes that can include multiple sites, and work over large distances. This is a commonly-used architecture industrial control systems, however there are concerns about SCADA systems being vulnerable to cyberwarfare or cyberterrorism attacks.
The SCADA software operates on a supervisory level as control actions are performed automatically by RTUs or PLCs. SCADA control functions are usually restricted to basic overriding or supervisory level intervention. A feedback control loop is directly controlled by the RTU or PLC, but the SCADA software monitors the overall performance of the loop. For example, a PLC may control the flow of cooling water through part of an industrial process to a set point level, but the SCADA system software will allow operators to change the set points for the flow. The SCADA also enables alarm conditions, such as loss of flow or high temperature, to be displayed and recorded.
Programmable logic controllers
PLCs can range from small modular devices with tens of inputs and outputs (I/O) in a housing integral with the processor, to large rack-mounted modular devices with a count of thousands of I/O, and which are often networked to other PLC and SCADA systems. They can be designed for multiple arrangements of digital and analog inputs and outputs, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in battery-backed-up or non-volatile memory.
History
Process control of large industrial plants has evolved through many stages. Initially, control was from panels local to the process plant. However this required personnel to attend to these dispersed panels, and there was no overall view of the process. The next logical development was the transmission of all plant measurements to a permanently-staffed central control room. Often the controllers were behind the control room panels, and all automatic and manual control outputs were individually transmitted back to plant in the form of pneumatic or electrical signals. Effectively this was the centralisation of all the localised panels, with the advantages of reduced manpower requirements and consolidated overview of the process.
However, whilst providing a central control focus, this arrangement was inflexible as each control loop had its own controller hardware so system changes required reconfiguration of signals by re-piping or re-wiring. It also required continual operator movement within a large control room in order to monitor the whole process. With the coming of electronic processors, high-speed electronic signalling networks and electronic graphic displays it became possible to replace these discrete controllers with computer-based algorithms, hosted on a network of input/output racks with their own control processors. These could be distributed around the plant and would communicate with the graphic displays in the control room. The concept of distributed control was realised.
The introduction of distributed control allowed flexible interconnection and re-configuration of plant controls such as cascaded loops and interlocks, and interfacing with other production computer systems. It enabled sophisticated alarm handling, introduced automatic event logging, removed the need for physical records such as chart recorders, allowed the control racks to be networked and thereby located locally to plant to reduce cabling runs, and provided high-level overviews of plant status and production levels. For large control systems, the general commercial name distributed control system (DCS) was coined to refer to proprietary modular systems from many manufacturers which integrated high-speed networking and a full suite of displays and control racks.
While the DCS was tailored to meet the needs of large continuous industrial processes, in industries where combinatorial and sequential logic was the primary requirement, the PLC evolved out of a need to replace racks of relays and timers used for event-driven control. The old controls were difficult to re-configure and debug, and PLC control enabled networking of signals to a central control area with electronic displays. PLCs were first developed for the automotive industry on vehicle production lines, where sequential logic was becoming very complex. It was soon adopted in a large number of other event-driven applications as varied as printing presses and water treatment plants.
SCADA's history is rooted in distribution applications, such as power, natural gas, and water pipelines, where there is a need to gather remote data through potentially unreliable or intermittent low-bandwidth and high-latency links. SCADA systems use open-loop control with sites that are widely separated geographically. A SCADA system uses remote terminal units (RTUs) to send supervisory data back to a control centre. Most RTU systems always had some capacity to handle local control while the master station is not available. However, over the years RTU systems have grown more and more capable of handling local control.
The boundaries between DCS and SCADA/PLC systems are blurring as time goes on. The technical limits that drove the designs of these various systems are no longer as much of an issue. Many PLC platforms can now perform quite well as a small DCS, using remote I/O and are sufficiently reliable that some SCADA systems actually manage closed-loop control over long distances. With the increasing speed of today's processors, many DCS products have a full line of PLC-like subsystems that weren't offered when they were initially developed.
In 1993, with the release of IEC-1131, later to become IEC-61131-3, the industry moved towards increased code standardization with reusable, hardware-independent control software. For the first time, object-oriented programming (OOP) became possible within industrial control systems. This led to the development of both programmable automation controllers (PAC) and industrial PCs (IPC). These are platforms programmed in the five standardized IEC languages: ladder logic, structured text, function block, instruction list and sequential function chart. They can also be programmed in modern high-level languages such as C or C++. Additionally, they accept models developed in analytical tools such as MATLAB and Simulink. Unlike traditional PLCs, which use proprietary operating systems, IPCs utilize Windows IoT. IPC's have the advantage of powerful multi-core processors with much lower hardware costs than traditional PLCs and fit well into multiple form factors such as DIN rail mount, combined with a touch-screen as a panel PC, or as an embedded PC. New hardware platforms and technology have contributed significantly to the evolution of DCS and SCADA systems, further blurring the boundaries and changing definitions.
Security
SCADA and PLCs are vulnerable to cyber attack. The U.S. Government Joint Capability Technology Demonstration (JCTD) known as MOSAICS (More Situational Awareness for Industrial Control Systems) is the initial demonstration of cybersecurity defensive capability for critical infrastructure control systems. MOSAICS addresses the Department of Defense (DOD) operational need for cyber defense capabilities to defend critical infrastructure control systems from cyber attack, such as power, water and wastewater, and safety controls, affect the physical environment. The MOSAICS JCTD prototype will be shared with commercial industry through Industry Days for further research and development, an approach intended to lead to an innovative, game-changing capabilities for cybersecurity for critical infrastructure control systems.
See also
Automation
Plant process and emergency shutdown systems
MTConnect
OPC Foundation
Safety instrumented system (SIS)
Control system security
Operational Technology
References
Further reading
Guide to Industrial Control Systems (ICS) Security, SP800-82 Rev2, National Institute of Standards and Technology, May 2015.
External links
Proview, an open source process control system
Telemetry
Control system
Control engineering
Manufacturing | Industrial control system | Engineering | 2,427 |
52,114,869 | https://en.wikipedia.org/wiki/Andres%20Jaramillo-Botero | Andres Jaramillo-Botero (born March 28, 1964) is a Colombian-American scientist and professor, working in nanoscale chemical physics, known for his contributions to first-principles based modeling, design, synthesis and characterization of nanostructured materials and devices.
Education and training
Jaramillo-Botero earned a B.S. in electrical engineering from Boston University in 1986, an M.Sc. in computer science from the State University of New York as a Fulbright scholar in 1989, under the supervision of Kanad Ghose and Peter Kogge, and a Doctorate degree in engineering from the Polytechnic University of Valencia (UPV) in 1998 (Valencia, Spain), under the supervision of Alfons Crespo (at UPV) and co-supervision of William A. Goddard III (at Caltech). His doctoral work, developed while at the California Institute of Technology and NASA's Jet Propulsion Laboratory, during 1996–1997, contributed time-lower bound solution and algorithms to the n-body dynamics problem and their application at multiple length scales, from molecular to macroscopic systems.
Career
Jaramillo-Botero began his academic career as an assistant professor in engineering and applied sciences at the Pontifical Xavierian University in 1990, where he reached full professorship by 1999. Since his early days at this institution, he served in various positions such as Member of the university’s board of directors, Engineering Faculty Dean, founding Director of the Doctoral program in Engineering and Applied Sciences, founding Director of the electronics engineering undergraduate program, and Director of the computer science undergraduate program. In 2001, Jaramillo-Botero was received into the Xavierian honor society for his contributions to science and academia in Colombia.
He joined the California Institute of Technology (Caltech) full-time in 2006, and relocated to the US as an Alien of extraordinary ability recipient (EB-1A category). At Caltech, he holds key positions as a Scientist-Lecturer in the Chemistry and Chemical Engineering division, and as the Director of Nanotechnology and Multiscale Science in the Materials and Process Simulation Center. He remains a distinguished professor in engineering and science and a member of the Board of Regents at the Pontifical Xavierian University in Colombia.
Research Work
Jaramillo-Botero developed an early interest for multibody dynamics control as a research scholar in Advanced Industrial Applications at the Robotics and Autonomous Machinery division of the Mechanical Engineering Laboratory (1992-1993, National Institute of Advanced Industrial Science and Technology or AIST), where he focused on dynamic real-time visual control of robotic systems. He transitioned from macroscopic to nanoscale multibody dynamics control and modeling during his research appointment with NASA’s Jet Propulsion Laboratory and Caltech (1996-1997). He continued to develop fundamental frameworks for designing atomic-scale manipulators with optimized dynamic response during postdoctoral appointments (2002 -2005), as a National Science Foundation (NSF) Fellow in the Nanoscale Science and Engineering program, at UCLA’s Institute for Pure and Applied Mathematics (IPAM), and, as an NSF Fellow in Computational Nanotechnology and Molecular Engineering, at Caltech.
Jaramillo-Botero is recognized for the development and application of first-principles-based physicochemical methods to study, design, characterize, synthesize, optimize and engineer nanostructured materials, devices, and systems.
His contributions span multiple fields of study, including: molecular hypervelocity impact phenomena in space missions, dynamics of materials in extreme conditions (non-adiabatic behavior), first-principles based atomistic and coarse-grain force fields and simulation methods to study complex chemical processes, some of which are embedded in widely used open source codes like LAMMPS, low-temperature crystalline thin film growth and characterization, single-molecule sensing and actuation nanodevices, and computational dynamics methods in large-scale multi body systems (from atomistic to continuum).
Jaramillo-Botero led the OMICAS Alliance as Scientific Director, an international, multi-institutional research effort spurred by the Colombian government under the World Bank PACES program to address food security and sustainable productivity, via Omics characterization and optimization of plant organisms. and the creation of the OMICAS Research Institute - iOMICAS at the Pontifical Xavierian University in Cali; a state of the art facility focused on translational research to address overarching challenges associated to health, food security, and productive sustainability.
Personal life
Jaramillo-Botero was raised, along with three siblings, to parents Jorge Jaramillo-Douat and Clara Ines Botero. Jaramillo-Botero is married to Maria Claudia Ojeda. They bore two children, Tomas (2004-) and Lucas (2000–2009).
U.S. Patents
He holds multiple US and European patents as of 2016.
References
American people of Colombian descent
Nanotechnologists
Living people
Boston University College of Engineering alumni
1964 births | Andres Jaramillo-Botero | Materials_science | 1,015 |
3,384,168 | https://en.wikipedia.org/wiki/Buncefield%20fire | The Buncefield fire was a major fire at an oil storage facility that started at 06:01 UTC on Sunday 11 December 2005 at the Hertfordshire Oil Storage Terminal, located near the M1 motorway, Hemel Hempstead, in Hertfordshire, England. The terminal was the fifth largest oil-products storage depot in the United Kingdom, with a capacity of about of fuel. The terminal is owned by Total UK Limited (60%) and Texaco (40%).
The first and largest explosion occurred near tank 912, which led to further explosions which eventually overwhelmed 20 large storage tanks.
The emergency services announced a major emergency at 06:08 and a firefighting effort began. The cause of the explosion was a fuel-air explosion in a vapour cloud of evaporated leaking petrol. The British Geological Survey monitored the event, which measured 2.4 on the Richter scale.
News reports described the incident as the biggest of its kind in peacetime Europe and certainly the biggest such explosion in the United Kingdom since the 1974 Flixborough disaster. The flames had been extinguished by the afternoon of 13 December 2005. However, one storage tank reignited that evening, which firefighters left to burn rather than attempting to extinguish it again.
The Health Protection Agency and the Major Incident Investigation Board provided advice to prevent incidents such as these in the future. The primary need is for safety measures to be in place to prevent fuel escaping the tanks in which it is stored. Added safety measures are needed for when fuel does escape, mainly to prevent it forming a flammable vapour and stop pollutants from poisoning the environment.
Incident
Explosion and fire
The first and largest explosion occurred at 06:01 UTC on Sunday, 11 December 2005 near container 912. Further explosions followed which eventually overwhelmed 20 large storage tanks.
From all accounts, it seems to have been an unconfined vapour cloud explosion of unusually high strengthalso known as a fuel-air explosion. Because of an inversion layer, the explosions were heard up to away; there were reports that they were audible in Belgium, France, and the Netherlands.
The British Geological Survey monitored the event, which measured 2.4 on the Richter scale. It was reported that people were woken in south London, and as far west as Wokingham about away, where in its southern suburb, Finchampstead, numerous people felt the shockwave after the initial explosion. Subsequent explosions occurred at 06:27 and 06:28.
Witnesses many miles from the terminal observed flames hundreds of feet high; the smoke cloud was visible from space, and from as far north as Lincolnshire about away. Damage from the blasts included broken windows at various buildings including the Holy Trinity church and Leverstock Green School, blown-in or warped front doors, and an entire wall being removed from a warehouse more than from the site. Buildings in neighbouring St Albans also suffered; Townsend School had serious blast damage, and a window was blown out of St Albans Abbey about away.
Several nearby office blocks were hit so badly that almost every window, front and back, was blown in as the explosion ripped through them. The timing of the explosion before work hours possibly prevented additional casualties. Reports also indicated that cars in nearby streets caught fire. The roof of at least one house was blown off. Buildings in the vicinity were evacuated by police, not only because of the smoke and possibility of more explosions, but because of the danger of structural damage making the buildings unstable.
There were 43 reported injuries; two people were deemed to be seriously injured enough to be kept in hospital, one in Watford General Hospital, with breathing difficulties, and another in Hemel Hempstead Hospital, although they were not in a life-threatening condition. Some early media reports spoke of eight fatalities, but these may have been persons missing. All members of staff from the terminal were accounted for.
Hertfordshire police and fire services and the member of parliament for the area, Mike Penning, said that there were seven fuel tanks on the site which, as of 14:00 on 12 December, had not been affected. These tanks were at risk of exploding if the fire were to spread.
Tackling the blaze
The emergency services announced a major emergency at 06:08 and a tremendous firefighting effort began. At peak times this effort consisted of 25 fire engines, 20 support vehicles and 180 fire fighters.
Around 150 firefighters were called immediately to the incident, and began tackling the blaze at 08:20 on the morning of 11 December, putting in containment measures before applying a large quantity of foam. The incident occurred close to junction 8 of the M1 motorway, which led to its closure and the setting up of a public exclusion area. It was estimated that this incident would be the largest "single-seat" fire in the world ever to be fought by a fire brigade, and foam supplies from sites all over the UK were drawn upon.
Plans had been in place to start using foam at midnight on 11 December, but were delayed by last-minute concerns over possible pollution of local rivers and underlying water sources. Six high volume pumps were used to extract of water per minute per secondfrom a reservoir from the fire, with six more high-volume pumps deployed at various locations to serve as boosters. Thirty-two thousand litres (7,039 imp gal) of fire fighting foam per minute were directed against the fire for just over four hours, after which the pumping rate was reduced. Half of the 20 individual fires were reported extinguished by midday.
By 16:30 on Monday 12 December, it was reported that a further two tank fires had been extinguished, but that one of the tanks extinguished earlier had ruptured and re-ignited, and was now threatening to cause the explosion of an adjacent tank. This led to the M1 motorway being closed again; the public exclusion area was widened, and firefighters were temporarily withdrawn until the risk posed by the threatened tank could be assessed.
Firefighting operations were resumed at about 20:00, and it was anticipated that all fires could be extinguished during the night. Further damage occurred to one of the storage tanks in the early hours of Tuesday morning, causing firefighters to be withdrawn once again, but operations resumed at 08:30. By midday on 13 December, all but three fires had been extinguished, although the largest tank was still burning. Bronze commandoperations on the groundwas visited by the Bishop of St Albans, the local vicar, and the industrial chaplain supporting the fire crews, to see how they were coping.
Firefighters were confident that the remaining fires could be extinguished during the day on Tuesday, 13 December. The smoke plume had been considerably reduced and was more grey, indicating the amount of vapourised water now combining with the smoke. It was reported at 16:45 that all tank fires had been extinguished, although some smaller fires persisted. 75% of firefighters for Hertfordshire were involved in fighting the fire, supported by 16 other brigades. The entire gold command operation, involving many agencies as well as all the emergency services, was run from Hertfordshire Constabulary's headquarters in Welwyn Garden City, some distance from the fire.
A further fire broke out during the early morning of 14 December. Firefighters were of the view that extinguishing it would leave the risk of petroleum vapour re-igniting or exploding, so it would be better to allow the fire, which was well contained, to burn itself out. Hertfordshire Fire Service's deputy chief Mark Yates stated that escaping petroleum vapour was the most likely cause of the original explosion and fire.
Smoke cloud
The black smoke cloud, which was visible from satellite photographs, drifted at a high altitude, around , towards Reading and Swindon, and could be seen across much of South East England.
The small particles in the smoke contained hydrocarbons, which can be an irritant but have a low toxicity and were not expected to cause any long-term harm. The Met Office issued warnings that the smoke in the atmosphere could come down in rainfall during the night of 11 December.
The fire resulted in 244 people requiring medical aidmainly on the first day of the fire. From those 117 had symptoms attributable to the incident, of whom 38 were members of the public. The majority of those visiting hospitals were from the rescue services and attended for precautionary check ups. Most of them had no symptoms, except for 63 emergency workers who suffered respiratory complaints, of which half were sore throats.
For the first two days of the fire, the high thermal energy made the plume highly buoyant; this, together with settled weather conditions, allowed the plume to rise to a great height with little cross-mixing. When the fire was reduced in intensity it was reported to be possible that the plume would be less buoyant and that ground-level smoke concentrations could then rise significantly. By 12 December, it was reported that the smoke cloud had reached northern France; it was expected to arrive in northern Spain by the weekend.
To investigate the smoke cloud the Facility for Airborne Atmospheric Measurements, a research aircraft operated jointly by NERC and the Met Office, made two flights on 12 and 13 December. In the first flight the edge of the plume was followed along the south coast of England. Carbon monoxide, nitrogen oxides and ozone concentrations were found to be low with soot particles being the major component in the cloud. The second flight went into the centre of the plume to obtain data to help forecasting and emergency teams.
Reactions and response
Evacuations and closures
Hundreds of homes in the Hemel Hempstead area were evacuated, and about 2,000 people had to find alternative accommodation; emergency services asked residents of the smoke-affected areas to close their windows and doors and to stay inside.
Hertfordshire Constabulary advised people who had houses with smashed windows to seek refuge with friends or family nearby if possible. Some people whose homes were damaged by the blast were placed in hotels, while others stayed in a nearby shopping centre. Total, the operator of the Buncefield depot, set up a helpline for people whose properties had been damaged by the explosion, and called in local authorities and the Salvation Army to provide accommodation or other help.
Concerns for public safety resulted in about 227 schools, libraries, and other public buildings across Hertfordshire and Buckinghamshire closing on 12 and 13 December. Police and local authorities advised residents to consult the Hertfordshire Direct website for up-to-date information.
Seventy-eight schools in Luton borough were closed on 13 December, along with a limited number of schools in Bedfordshire, on the advice of Hertfordshire's Health Protection Agency that all schools within a radius of the incident site should be closed because of concerns surrounding the effect of the smoke plume on children's health. Schools reopened as normal on 14 December.
Transport disruption
The incident occurred close to junction 8 of the M1 motorway. The motorway was shut between junctions 12 and 6aabout shortly after the incident. Other roads in the vicinity, including the short M10 motorway (now part of the A414 road), were also closed.
Some local petrol stations reported long queues as people started panic buying. A spokesman for the Department of Trade and Industry gave assurances that no petrol shortage was likely to result from the incident.
The oil terminal supplied 30% of Heathrow Airport's fuel, and because of the fire, the airport had to start rationing fuel. Some long-haul flights to Australia, the Far East, and South Africa had to make an intermediate stop at Stansted Airport or other European airports to refuel, while short-haul operators were asked to fuel their aircraft for the round trip before flying to Heathrow. Some aircraft were only allowed 40% of the fuel they would normally take on board. Fuel shortages continued for months after the explosion.
Business disruption
In the Maylands Industrial area the worst affected buildings were the Northgate Information Solutions headquarters and the Fujifilm building. These buildings were so badly damaged they were rendered completely unusable. Demolition of the Fujifilm building began soon afterwards, and by June 2006 it had been completely removed from the site. Although the Northgate and Fujifilm buildings were closest to the blast, the surrounding Catherine House (to the north), Keystone Distribution building (to the west), 3Com Corporation, and RO buildings (to the south), were also extensively damaged. ASOS lost £5 million of inventory and could not sell during the Christmas shopping season. In all, six buildings were designated for demolition and 30 more required major repairs before they could be reoccupied.
As a result of the destruction of the equipment in the Northgate building several websites hosted there were inaccessibleincluding that of the Labour Party. Addenbrooke's Hospital in Cambridge was also affected; its IT system dealing with admissions and discharges had to be replaced for several days by a manual system.
A number of companies were affected by inability to reach their premises even where the premises themselves were largely unaffected by the blast. Criticism was expressed by local citizens and the local MP as originally the depot had been constructed away from other buildings, but that developmental pressures had led to both houses and commercial premises being built near the depot.
Groundwater pollution
In May 2006 Three Valleys Water announced that it had detected the persistent, bioaccumulative, and toxic fluorosurfactant perfluorooctane sulfonate (PFOS)which is used in fire fighting foamin a ground water bore hole close to the Buncefield site. It stated that no water from this well entered the public water supply and that a nearby well and pumping station had been closed since the fire as a precaution. The chemical is a known health risk and the UK government had been about to ban its use.
However just before the announcement, the Drinking Water Inspectorate announced that it was increasing the safe level of the chemical in drinking water. Hemel Hempstead MP, Mike Penning accused the government of changing the rules to suit the situation in which PFOS levels in drinking water in the area may rise in the future. Most of the fuel burned outrather than spilling into the soil, so the impact on surrounding land and the water table was limited.
Inquiry
A government inquiry held jointly by the Health and Safety Executive (HSE) and the Environment Agency was started, but calls for a full public inquiry were declined. The Board included Tony Newton, Baron Newton of Braintree; Prof Dougal Drysdale, an authority on fire safety; and Dr Peter Baxter, a medical expert. Environment Agency and HSE staff were also on the board. Its aim was to identify the immediate causes of the explosion, rather than consider who was to blame for any deficiencies, so as not to prejudice further legal proceedings.
An initial progress report by the Major Incident Investigation Board on 21 February 2006 did not go into the causes of the explosion, but summed up the event and the immediate reaction from the emergency services. A second progress report, published on 11 April 2006, looked at the environmental impact.
A further announcement was made on 9 May 2006 about the sequence of events which caused the explosion. Starting at 19:00 on the evening of 10 December 2005, Tank 912, towards the north west of the main depot, was filled with unleaded petrolfrom the Coryton Refinery located in Essex, England. At midnight the terminal closed, and a check was made of the contents of tanks, which found everything normal. Normally the gauges monitor the level of the fuel in the tank as it fills from the particular pipeline. From about 03:00 the level gauge for Tank 912 began to indicate an unchanging level reading, despite it being filled at per hour.
Calculations show that the tank would have begun to overflow at about 05:20. There is evidence suggesting that a high-level switch, which should have detected that the tank was full and shut off the supply, failed to operate. The switch failure should have triggered an alarm, but it too appears to have failed. Forty-one minutes later, an estimated of petrol would have spilled down the side of the tank through the roof vents onto the ground inside a bund walla semi-enclosed compound surrounding several tanks.
An overflow such as this results in the rapid formation of a rich fuel and air vapour. CCTV footage showed such a vapour flowing out the bund wall from around 05:38. By 05:50 the vapour started flowing off the site, near the junction of Cherry Tree and Buncefield Lane. Around 05:50 the rate at which fuel was being pumped into the tank increased dramatically. Initially the fuel was pumped in at per hour, but it increased to about per hour. By 06:01, when the first explosion occurred, the cloud which was initially about deep, thickened to and had spread beyond the boundaries of the site.
The extent of the damage meant it was not possible to determine the exact source of ignition, but possibilities include an emergency generator and the depot's fire pump system. The investigators did not believe that it was caused either by the driver of a fuel tanker, as had been speculated, or by anyone using a mobile phone. It was felt unlikely that the explosion had a widespread effect on air quality at ground level.
Legal action
Civil liability
A total of 2,700 claims were filed by residents, businesses and insurers. A group of 146 claimants were hoping to bring a class action against Hertfordshire Oil Storage Ltd. On 17 March 2006 a High Court official, Senior Master Turner, adjourned a hearing on whether to permit the class action until October 2006. Claimants including insurance companies, small businesses and about 280 families whose properties were damaged or destroyed were claiming up to £1 billion in damages.
Several court cases resulted from the explosion, although the main trial to determine who was liable for the damage commenced at the High Court in October 2008. The BBC quoted Cheetah Courierswhich suffered a 20% drop in turnover because of the explosions, resulting in losses of around £300,000 to £400,000. The company was located in offices on an industrial estate from the depot.
An initial trial concluded on 23 May 2008 when Mr Justice David Steel issued a summary judgment after hearing that both Total and Hertfordshire Oil Storage Ltd (HOSL) had agreed that negligence was the cause. In the main trial, Total UK claimed that the duty supervisor at the time was responsible for the explosion, but refused to admit either civil or criminal liability for the incident. Total UK argued that it should not be liable for damages because it could not reasonably have foreseen that it would cause the destruction it did. On 20 March 2009 the High Court found Total liable for the blast, saying that it was satisfied that Total had control of tank filling operations at the Buncefield depot. The judgement left the company facing damage claims of around £700 million.
Total appealed the judgement, but the appeal was dismissed in a hearing on 4 March 2010.
Criminal liability
The site is covered by the COMAH regulations. The Control of Major Accidents and Hazards Regulations are jointly enforced by the competent authority which is formed of the Environment Agency and the Health and Safety Executive. They carried out an investigation during and following the fire.
In April 2010, the five companies accused of causing the explosion faced a criminal prosecution brought by the Health and Safety Executive and the Environment Agency. Two defendants, Total UK and British Pipeline Agency Limited, had already pleaded guilty to offences under the Health and Safety at Work Act. The remaining three, Hertfordshire Oil Storage Ltd, TAV Engineering Ltd and Motherwell Control Systems were found guilty in June 2010. TAV Engineering Ltd and Motherwell Control Systems were found guilty of failing to protect their employees. Hertfordshire Oil Storage Ltd was found guilty of failing to prevent major accidents and limit their effects and then pleaded guilty to causing pollution to enter controlled waters underlying the vicinity around the site, contrary to the Water Resources Act.
Sentencing took place in July 2010. Total UK was fined £3.6 m, plus £2.6 m in costs. Hertfordshire Oil Storage Limited was fined £1.45 m and £1 m in costs. The British Pipeline Agency was fined £300,000 plus £480,000 costs. Motherwell Control Systems and TAV Engineering were fined £1,000 each. Local MP Mike Penning called the modest fines "insulting".
The terminal
The Hertfordshire Oil Storage Terminal (HOSLHertfordshire Oil Storage Ltd), generally known as the Buncefield complex, was the fifth largest oil-products storage depot in the UK, with a capacity of about of fuel, although it was not always full. This was about 8% of UK oil storage capacity.
The HOSL is a major hub on the UK's oil pipeline network (UKOP) with pipelines to the Lindsey Oil Refinery and Stanlow Refinery and is an important fuel source to the British aviation industry, providing aircraft fuel for local airports including Gatwick, Heathrow and Luton airports. About half of the complex is dedicated to the storage of aviation fuel. The remainder of the complex stores oil, kerosene, petrol and diesel fuel for petrol stations across much of the South-East of England. The terminal is owned by TOTAL UK Limited (60%) and Texaco 40%.
The seat of the fire, and the worst damaged section, was "HOSL West", used by Total and Texaco to store a variety of fuels, and the neighbouring British Pipeline Agency area.
Causes
The final report of the Major Incident Investigation Board (MIIB) was written in 2008 and released in February 2011. The investigation found that Tank 912 at the Buncefield oil storage depot was being filled with petrol. The tank had a level gauge that employees used to monitor the level manually, and an independent high-level switch which would shut off inflow if the level got above a certain setpoint.
On Tank 912, the manual gauge was stuck and the independent shut-off switch was inoperative, meaning that the tank was being "filled blind" with petrol (i.e., being filled without a clear indication of the level). Eventually Tank 912 filled up completely, the petrol overflowed through vents at the top, and formed a vapour cloud near ground level, which ignited and exploded. The fires from the explosion then lasted for five days.
The investigation found that the level gauge had stuck at random times after a tank service in August 2005, but it did not concern maintenance contractors or site management. The independent shut-off switch was not fitted with a critical padlock to allow its check lever to work. Secondary containment (meant to trap the petrol in a retaining wall around the tank) failed and allowed petrol to flow out. Tertiary containment (drains and catchment areas to prevent release of spilled chemicals to the environment) also failed, and fuel and firefighting foam entered groundwater supplies. The investigation found secondary and tertiary containment to be inadequately designed and poorly maintained.
Wider management failings were found by the investigation to have contributed to the explosion: management safety checks at the site were found to be deficient and not properly followed. Site staff did not have control over the flow rates and timing of two of the three inlet sources, meaning that they did not have enough information to properly manage the storage of incoming fuel. Further, overall throughput had increased, reducing wait times further and shifting the emphasis to process operations instead of process safety.
Aftermath
Soon after the incident the Health Protection Agency was stripped of its remit to provide air quality data and it was passed on to the Environment Agency which forms part of the Major Accident Investigation Board.
Remembrance
An anniversary service was held in Holy Trinity Church Leverstock Green on Sunday, 10 December 2006, at which the Bishop of St Albans spoke, calling again for a full public inquiry, for assurances that the local hospital would maintain its accident and emergency department, and for the community to continue to build on good and new relationships formed because of the blast.
Reconstruction
To rebuild the damaged parts of the site, the relevant approval from Dacorum Borough Council would be needed. The BP section of the site is a good way from the explosion and survived with very little damage, but it was inoperative as of 2009. BP is exploring plans for the future use of this part of the site, and has indicated a number of priorities, including the reopening of the fuel pipelines to Heathrow. It is considering using its section to store aviation fuel and as a distribution centre for motor fuel, but at a much-reduced level. In late 2009, Total UK submitted plans for the reconstruction of the oil depot. The reconstruction of the site has been taking place since March 2013.
Commemoration
On the roundabout at the entrance to Hemel, the "Phoenix Gateway" sculpture was designed by Jose Zavala to symbolize the recovery of the town from the Buncefield oil depot explosion.
See also
2021 Balongan refinery explosion
2009 Cataño oil refinery fire
2009 Jaipur fire
1987 Grangemouth Refinery explosion and fire
1983 Milford Haven Refinery fire
References
Further reading
External links
Buncefield explosion prosecution Prosecution resulting from Buncefield explosion.
The Buncefield Investigation Official government enquiry.
Hertfordshire Constabulary Aerial photographs of the fire in progress.
Buncefield Terminal Incident Pages on the HOSL website.
Hemel Today Coverage of the High Court compensation trial.
Aerial photo (January 2006) of aftermath of the fire
Aerial photo of the Buncefield terminal. Other .
Explosions in 2005
History of Hertfordshire
Explosions in England
Building and structure fires in England
2000s fires in the United Kingdom
2005 fires in Europe
2005 industrial disasters
2005 disasters in the United Kingdom
2005 in England
2000s in Hertfordshire
Engineering failures
Petroleum infrastructure in the United Kingdom
Gas explosions in the United Kingdom
Dacorum
Disasters in Hertfordshire
TotalEnergies
Hemel Hempstead
December 2005 events in the United Kingdom
Industrial fires and explosions in the United Kingdom
Factory fires | Buncefield fire | Technology,Engineering | 5,228 |
48,851,576 | https://en.wikipedia.org/wiki/Wound%20healing%20assay | A wound healing assay is a laboratory technique used to study cell migration and cell–cell interaction. This is also called a scratch assay because it is done by making a scratch on a cell monolayer and capturing images at regular intervals by time lapse microscope.
It is specifically a 2D cell migration approach to semi-quantitatively measure cell migration of a sheet of cells. This scratch can be made through various approaches, such as mechanical, thermal, or chemical damage. The purpose of this scratch is to produce a cell-free area in hopes of inducing cells to migrate and close the gap. The scratch test is only ideal for cell types that migrate as a collective epithelial sheets and not useful for non-adherent cells. Specifically, this assay isn't ideal for chemotaxis studies.
Advantages and disadvantages
This laboratory technique has various advantages. First, these tests are relatively cheap, relatively straightforward and allow for real-time measurements. Additionally, the testing conditions can be easily adjusted to fit different experimental objectives. This approach also allows for a strong directional migratory response making quantifying data simple.
One limitation of this assay is that there could be inconsistencies with the depth and size of the scratch. When the scratch is done manually, it's susceptible to 'ragged' edge boundaries, which make analyzing data more difficult. Also, the damage could physically damage the cells adjacent to the wound and create inaccurate wound size areas. This limitation is slowly becoming less of an issue with automated technologies. The Electric Cell Impendance Sensing assays utilize to prevent damage to the cells in the underlying extracellular matrix that can likely happen with the manual scratching approaches. Additionally, the Woundmaker makes fast and uniform wounds across various numbered well-plates options (96 or 384) and allows for high throughput screening, which is a major advantage for various medical research studies.
Despite the new technology that is increasing this assay's accuracy and efficacy, there are still confounding factors that can skew the assay results, such as cell "crowding", cell/cell adhesion effects and matrix effects. Additionally, there is still mention with the problem of accumulation of cells at the edge of the scratch, making the cell densities uneven.
There are some skeptics who think that the scratch created for the assay isn't a very accurate representation of an actual wound. This is very likely true as real wounds are inherently more complex, but this assay does allow for collective cell movements under defined experimental conditions to provide some insight.
Despite it being described as straightforward, the technique has been criticized because of inconsistencies in its application from one experiment to another.
Standard laboratory protocol
Outlined is a standard approach to carry-out this assay without the advanced technology:
Plate cells of choice in growth medium into a live cell imaging dish or chamber slide. It is important to ensure that a monolayer is formed as clumps will provide inaccurate results due to an uneven cell density. Titrating the cells to determine the optimal plating density is necessary.
When the confluency of the cells are ideal, use a pipette tip to scratch a wound through the entire center of the well. As mentioned previously, this is where the potential inconsistency comes into play with this assay. If the scratch is made manually, it is important to make sure that the wound is visible on both side of the field of view and should be around 0.5 mm wide.
The cells can then be placed on a microscope with a relative objective of 20x.
Begin time-lapse microscopy and adjust the parameters according to the variety of cells studying. Fast-growing cells may require shorter time intervals to acquire more accurate cell speed.
Applications
Quantitative/qualitative analysis of collective cell migration under changeable experimental conditions.
Analysis of cell-matrix and cell-cell interactions with respect to cell migration.
High-throughput screens for:
Cancer cell migration genes
Small molecules
Drug discovery
Metrics to quantify cell migration
Rate of cell migration:
where
RM = Rate of cell migration
WI = Initial wound width
Wf = Final wound width
t = duration of migration
Relative wound density:
where
wt = Density of the wound area at time t
ct = Density of the cell area at time t
The above are basic metrics that can be measured with this assay. However efforts are still being made to improve the interpretation of this assay. Three different measurements: direct rate average, regression rate average and average distance regression rate have been evaluated. Direct rate average and average distance regression rate were more resistant to outliers, whereas regression rate average were more sensitive to outliers.
Cell migration
The scratch assay is a great tool to study cell migration since this mechanism is involved in many different physiological aspects. Cell migration plays a huge role in re-epithelialization of the skin and so the study of cell migration can provide advancements in understanding non-healing wounds. Cell migration is also fundamental in developmental processes such as gastrulation and organogenesis. Cell migration is also involved in immune responses and cancer metastases.
Cancer biology
With technological advances, this assay is becoming very beneficial especially in the cancer biology realm. A study was performed to better understand the role that claudin-7, a family of tight junction proteins, plays in cell migration in a type of human lung cancer cells. Due to the slower migration rate of claudin-7 knockdown cells, it supports the idea that this protein is important in cell migration an cell's ability to metastasize. Cells undergo sheet migration due to a multitude of signals and mechanisms when trying to close a wound, which is believed to be similar to the underlying mechanisms involved in metastasis.
Alternatives to the wound healing assay
Using label-free live cell imaging devices based on quantitative phase imaging, it has been shown that cell motility is highly correlated to wound healing and transwell assay results. The advantage of this fully automated approach is that quantification of cell motility does not require specific sample preparation, allowing cell proliferation to be simultaneously quantified as well.
References
Healing
Laboratory techniques | Wound healing assay | Chemistry | 1,251 |
14,997,614 | https://en.wikipedia.org/wiki/Fruit%20brandy | Fruit brandy (or fruit spirit) is a distilled beverage produced from mash, juice, wine or residues of edible fruits. The term covers a broad class of spirits produced across the world, and typically excludes beverages made from grapes, which are referred to as plain brandy (when made from distillation from wine) or pomace brandy (when made directly from grape pomace). Apples, pears, apricots, plums and cherries are the most commonly used fruits.
Definition
According to a legal definition in the United States, a "fruit brandy" is distilled "solely from the fermented juice or mash of whole, sound, ripe fruit, or from standard grape, citrus, or other fruit wine, with or without the addition of not more than 20 percent by weight of the pomace of such juice or wine, or 30 percent by volume of the lees of such wine, or both."
In the European Union, fruit spirits may not be labeled as "fruit brandy"; instead, the legal English denomination is fruit spirit, which is "produced exclusively by the alcoholic fermentation and distillation of fleshy fruit or must of such fruit, berries or vegetables, with or without stones". A great number of European fruit spirits have a protected designation of origin, and are labeled with their respective protected names instead of "fruit spirit" ("apricot spirit", etc.). Cider spirit and perry spirit (fruit spirit distilled from cider or perry) form a separate legal category. Some fruit spirits may be labeled with alternative names such as kirsch (cherry spirit) or slivovitz (plum spirit) regardless of their country of origin. Cider Brandy is defined in EC law as a distinct cask-aged product produced in the UK, distilled from cider made by fermenting traditional cider apple varieties. This includes “Somerset Cider Brandy”, which is specifically protected as a Geographical Indication (GI) within the United Kingdom. It is typically sold at 42% ABV.
In British usage, "fruit brandy" may also refer to liqueurs obtained by maceration of whole fruits, juice or flavoring in a distilled beverage, and such liqueurs are legally labeled as "cherry brandy", "apricot brandy" etc. all across the European Union. Such beverages are used similarly to cordials, and as an ingredient in cocktails and cakes. Fruit spirits obtained by distillation are often referred to by the French term eau de vie.
Fruit spirit usually contains 40% to 45% ABV (80 to 90 US proof). It is often colourless. Fruit spirit is customarily drunk chilled or over ice, but is occasionally mixed.
Types
Including some of the above, there are about 80 different kinds of fruit spirits in the European Union, registered with protected designations of origin from Germany, France, Italy, Portugal, Luxembourg, Austria, Hungary, Slovakia, Bulgaria, Romania and Spain. Most of these fruit spirits are named after their region of origin and base ingredients. For example: Schwarzwälder Kirschwasser (cherry spirit of the Black Forest), Framboise d'Alsace (raspberry of Alsace), Aprikot dell'Alto Adige (apricot of South Tyrol), etc. They are often regulated more strictly than generic fruit spirits: as well as limiting their region of origin, restrictions may include fruit variants, mashing and fermenting technology, distilling apparatus, barrel aging, etc.
Among the better known fruit spirits are:
Applejack is an American apple spirit made from the distillation of hard cider. It was once made by fractional freezing, which would disqualify it as a proper brandy.
Brinjevec is a Slovenian spirit distilled from ground and fermented juniper berries.
Buchu is a South African spirit flavoured with extracts from Agathosma species.
Calvados is an apple spirit from the French region of Lower Normandy.
Coconut brandy is actually made from the sap of palmyra palm flowers.
Damassine brandy is made with the prune fruit of the Damassinier tree in the Jura Mountains of Switzerland.
Eau de vie is a French term for colorless fruit spirit. This term is also applied to grape-based brandy other than Armagnac and Cognac.
Himbeergeist is a raspberry-based spirit produced mainly in Germany and the Alsace region of France as an infusion of macerated fruit in neutral spirit which is then distilled. While not a true fruit brandy (its correct denomination is Geist), it is typically referred to as a form of Schnaps.
Kirschwasser is a fruit spirit made from cherries.
Kukumakranka is a South African spirit flavored with the fruit of the Kukumakranka plant.
Marpha is a Nepalese fruit brandy produced in the Himalayan region of Mustang district.
Obstler is a German word for fruit spirit (Schnaps), often referred to as "Schnapps" in English.
Pálenka or "Pálené" is a common traditional description for Slovak spirit. It must be distilled from Slovakian wild or domestic fruits.
Pálinka is a traditional Hungarian fruit spirit . It can only be made with fruits from Hungary, such as plums, apricots, peaches, elderberries, pears, apples, or cherries.
Poire Williams is made from the Williams pear, also known as the Bartlett pear.
Rakia is a type of fruit spirit produced in Albania, Bosnia and Herzegovina, Bulgaria, Croatia, North Macedonia, Montenegro and Serbia: it may be made from plums, apples, quinces, pears, apricots, cherries, mulberries, or grapes.
Slivovitz is a straw- to yellow-colored plum spirit produced in Bosnia and Herzegovina, Bulgaria, Croatia, Czech Republic, Macedonia, Poland, Serbia, Slovakia, and Slovenia.
Somerset Cider Brandy an apple brandy which dates back to 1678 and which obtained European protected status in 2011.
Țuică, also known as horincă or turţ, is a clear Romanian plum spirit. Other Romanian fruit spirits, often distilled from apples, pears, apricots, mulberries, peaches, quinces, or mixtures of these, are colloquially known as Rachiu.
Health issues
Moonshine
Although methanol is not produced in toxic amounts by fermentation of sugars from grain starches, it is a major occurrence in fruit spirits. However, in modern times, reducing methanol with the absorption of a molecular sieve is a practical method for production.
See also
Cordial
Aperitif
References
Distilled drinks | Fruit brandy | Chemistry | 1,411 |
26,412,304 | https://en.wikipedia.org/wiki/1000%20Plant%20Genomes%20Project | The 1000 Plant Transcriptomes Initiative (1KP) was an international research effort to establish the most detailed catalogue of genetic variation in plants. It was announced in 2008 and headed by Gane Ka-Shu Wong and Michael Deyholos of the University of Alberta. The project successfully sequenced the transcriptomes (expressed genes) of 1,000 different plant species by 2014; its final capstone products were published in 2019.
1KP was a large-scale (involving many organisms) sequencing projects designed to take advantage of the wider availability of high-throughput ("next-generation") DNA sequencing technologies. The similar 1000 Genomes Project, for example, obtained high-coverage genome sequences of 1,000 individual people between 2008 and 2015, to better understand human genetic variation. The initiative provided a template for further planetary-scale genome projects, including the 10KP Project—sequencing the whole genomes of 10,000 plants, and the Earth BioGenome Project—aiming to sequence, catalogue, and characterize the genomes of all of Earth's eukaryotic biodiversity.
Goals
, the number of classified green plant species was estimated to be around 370,000, however, there are probably many thousands more yet unclassified. Despite this number, very few of these species have detailed DNA sequence information to date; 125,426 species in GenBank, , but most (>95%) having DNA sequence for only one or two genes. "...almost none of the roughly half million plant species known to humanity has been touched by genomics at any level". The 1000 Plant Genomes Project aimed to produce a roughly a 100x increase in the number of plant species with available broad genome sequence.
Evolutionary relationships
There have been efforts to determine the evolutionary relationships between the known plant species, but phylogenies (or phylogenetic trees) created solely using morphological data, cellular structures, single enzymes, or on only a few sequences (like rRNA) can be prone to error; morphological features are especially vulnerable when two species look physically similar though they are not closely related (as a result of convergent evolution for example) or homology, or when two species closely related look very different because, for example, they are able to change in response to their environment very well. These situations are very common in the plant kingdom. An alternative method for constructing evolutionary relationships is through changes in DNA sequence of many genes between the different species which is often more robust to problems of similar-appearing species. With the amount of genomic sequence produced by this project, many predicted evolutionary relationships could be better tested by sequence alignment to improve their certainty. With 383,679 nuclear gene family phylogenies and 2,306 gene age distributions with Ks plots used in the final analysis and shared in GigaDB alongside the capstone paper.
Biotechnology applications
The list of plant genomes sequenced in the project was not random; instead plants that produce valuable chemicals or other products (secondary metabolites in many cases) were focused on in the hopes that characterizing the involved genes will allow the underlying biosynthetic processes to be used or modified. For example, there are many plants known to produce oils (like olives) and some of the oils from certain plants bear a strong chemical resemblance to petroleum products like the Oil palm and hydrocarbon-producing species. If these plant mechanisms could be used to produce mass quantities of industrially useful oil, or modified such that they do, then they would be of great value. Here, knowing the sequence of the plant's genes involved in the metabolic pathway producing the oil is a large first step to allow such utilization. A recent example of how engineering natural biochemical pathways works is Golden rice which has involved genetically modifying its pathway, so that a precursor to vitamin A is produced in large quantities making the brown-colored rice a potential solution for vitamin A deficiency. This is concept of engineering plants to do "work" is popular and its potential would dramatically increase as a result of gene information on these 1000 plant species. Biosynthetic pathways could also be used for mass production of medicinal compounds using plants rather than manual organic chemical reactions as most are created currently.
One of the most unexpected results of the project was the discovery of multiple novel light-sensitive ion-channels used extensively for optogenetic control of neurons discovered through sequencing and physiological characterization of opsins from over 100 species of alga species by the project. The characterization of these novel channelrhodopsin sequences providing resources for protein engineers who would normally have no interest in or ability to generate sequence data from these many plant species. A number of biotech companies are developing these channelrhodopsin proteins for medical purposes, with many of these optogenetic therapy candidates under clinical trials to restore vision for retinal blindness. The first published results of these treating retinitis pigmentosa coming out in July 2021.
Project approach
Sequencing was initially done on the Illumina Genome Analyzer GAII next-generation DNA sequencing platform at the Beijing Genomics Institute (BGI Shenzhen, China), but later samples were run on the faster Illumina HiSeq 2000 platform. Starting with the 28 Illumina Genome Analyzer next-generation DNA sequencing machines, these were eventually upgraded to 100 HiSeq 2000 sequencers at the Beijing Genomics Institute. The initial 3Gb/run (3 billion base pairs per experiment) capacity of each of these machines enabled fast and accurate sequencing of the plant samples.
Species selection
The selection of plant species to be sequenced was compiled through an international collaboration of the various funding agencies and researcher groups expressing their interest in certain plants. There was a focus on those plant species that are known to have useful biosynthetic capacity to facilitate the biotechnology goals of the project, and selection of other species to fill in gaps and explain some unknown evolutionary relationships of the current plant phylogeny. In addition to industrial compound biosynthetic capacity, plant species known or suspected to produce medically active chemicals (such as poppies producing opiates) were assigned a high priority to better understand the synthesis process, explore commercial production potential, and discover new pharmaceutical options. A large number of plant species with medicinal properties were selected from traditional Chinese medicine (TCM). The completed list of selected species can be publicly viewed on the website, and methodological details and data access details have been published in detail.
Transcriptome vs. genome sequencing
Rather than sequencing the entire genome (all DNA sequence) of the various plant species, the project sequenced only those regions of the genome that produce a protein product (coding genes); the transcriptome. This approach is justified by the focus on biochemical pathways where only the genes producing the involved proteins are required to understand the synthetic mechanism, and because these thousands of sequences would represent adequate sequence detail to construct very robust evolutionary relationships through sequence comparison. The numbers of coding genes in plant species can vary considerably, but all have tens of thousands or more making the transcriptome a large collection of information. However, non-coding sequence makes up the majority (>90%) of the genome content. Although this approach is similar conceptually to expressed sequence tags (ESTs), it is fundamentally different in that the entire sequence of each gene will be acquired with high coverage rather than just a small portion of the gene sequence with an EST. To distinguish the two, the non-EST method is known as "shotgun transcriptome sequencing".
Transcriptome shotgun sequencing
mRNA (messenger RNA) is collected from a sample, converted to cDNA by a reverse transcriptase enzyme, and then fragmented so that it can be sequenced. Other than transcriptome shotgun sequencing, this technique has been called RNA-seq and whole transcriptome shotgun sequencing (WTSS). Once the cDNA fragments are sequenced, they will be de novo assembled (without aligning to a reference genome sequence) back into the complete gene sequence by combining all of the fragments from that gene during the data analysis phase. A new a de novo transcriptome assembler designed specifically for RNA-Seq was produced for this project, SOAPdenovo-Trans being part of the SOAP suite of genome assembly tools from the BGI.
Plant tissue sampling
The samples came from around the world, with a number of particularly rare species being supplied by botanical gardens such as the Fairy Lake Botanical Garden (Shenzhen, China). The type of tissue collected was determined by the expected location of biosynthetic activity; for example if an interesting process or chemical is known to exist primarily in the leaves, leaf sample was used. A number of RNA-sequencing protocols were adapted and tested for different tissue types, and these were openly shared via the protocols.io platform.
Potential limitations
Since only the transcriptome was sequenced, the project did not reveal information about gene regulatory sequence, non-coding RNAs, DNA repetitive elements, or other genomic features that are not part of the coding sequence. Based on the few whole plant genomes collected so far, these non-coding regions will in fact make up the majority of the genome, and the non-coding DNA may actually be the primary driver of trait differences seen between species.
Since mRNA was the starting material, the amount of sequence representation for a given gene is based on the expression level (how many mRNA molecules it produces). This means that highly expressed genes get better coverage because there is more sequence to work from. The result, then, is that some important genes may not have been reliably detected by the project if they are expressed at a low level yet still have important biochemical functions.
Many plant species (especially agriculturally manipulated ones) are known to have undergone large genome-wide changes through duplication of the whole genome. The rice and the wheat genomes, for example, can have 4-6 copies of whole genomes (wheat) whereas animals typically only have 2 (diploidy). These duplicated genes may pose a problem for the de novo assembly of sequence fragments, because repeat sequences confuse the computer programs when trying to put the fragments together, and they can be difficult to track through evolution.
Comparison with the 1000 Genomes Project
Similarities
Just as the Beijing Genomics Institute in Shenzhen, China is one of the major genomics centers involved in the 1000 Genomes Project, the institute is the site of sequencing for the 1000 Plant Genomes Project. Both projects are large-scale efforts to obtain detailed DNA sequence information to improve our understanding of the organisms, and both projects will utilize next-generation sequencing to facilitate a timely completion.
Differences
The goals of the two projects are significantly different. While the 1000 Genomes Project focuses on genetic variation in a single species, the 1000 Plant Genomes Project looks at the evolutionary relationships and genes of 1000 different plant species.
While the 1000 Genomes Project was estimated to cost up to $50 million USD, the 1000 Plant Genomes Project was not as expensive; the difference in cost coming from the target sequence in the genomes. Since the 1000 Plant Genomes Project only sequenced the transcriptome, whereas the human project sequenced as much of the genome as is decided feasible, there is a much lower amount of sequencing effort needed in this more specific approach. While this means that there was less overall sequence output relative to the 1000 Genomes Project, the non-coding portions of the genomes excluded in the 1000 Plant Genomes Project were not as important to its goals like they are to the human project. So then the more focused approach of the 1000 Plant Genomes Project minimized cost while still achieving its goals.
Funding
The project was funded by Alberta Innovates - Technology Futures (merger of iCORE ), Genome Alberta, the University of Alberta, the Beijing Genomics Institute (BGI), and Musea Ventures (a USA-based private investment firm). To date, the project received $1.5 million CAD from the Alberta Government and another $0.5 million from Musea Ventures. In January 2010, BGI announced that it would be contributing $100 million to large-scale sequencing projects of plants and animals (including the 1000 Plant Genomes Project, and then following on to the 10,000 Plant Genome Project).
Related projects
The 1000 Genomes Project – A Deep Catalog of Human Genetic Variation
The 1001 Genomes Project – Sequencing the whole genome of 1,001 Arabidopsis strains
Genome 10K – Whole genome sequence of 10,000 vertebrate species
See also
References
External links
Genome projects | 1000 Plant Genomes Project | Biology | 2,535 |
6,982,923 | https://en.wikipedia.org/wiki/Adaptive%20mutation | Adaptive mutation, also called directed mutation or directed mutagenesis is a controversial evolutionary theory. It posits that mutations, or genetic changes, are much less random and more purposeful than traditional evolution, implying that organisms can respond to environmental stresses by directing mutations to certain genes or areas of the genome. There have been a wide variety of experiments trying to support (or disprove) the idea of adaptive mutation, at least in microorganisms.
Definition
The most widely accepted theory of evolution states that organisms are modified by natural selection where changes caused by mutations improve their chance of reproductive success. Adaptive mutation states that rather than mutations and evolution being random, they are in response to specific stresses. In other words, the mutations that occur are more beneficial and specific to the given stress, instead of random and not a response to anything in particular. The term stress refers to any change in the environment, such as temperature, nutrients, population size, etc. Tests with microorganisms have found that for adaptive mutation, more of the mutations observed after a given stress were more effective at dealing with the stress than chance alone would suggest is possible. This theory of adaptive mutation was first brought to academic attention in the 1980s by John Cairns.
Recent studies
Adaptive mutation is a controversial claim leading to a series of experiments designed to test the idea. Three major experiments are the SOS response, responses to starvation in Escherichia coli, and testing for revertants of a tryptophan auxotroph in Saccharomyces cerevisiae (yeast).
Lactose starvation
The E. coli strain FC40 has a high rate of mutation, and so is useful for studies, such as for adaptive mutation. Due to a frameshift mutation, a change in the sequence that causes the DNA to code for something different, FC40 is unable to process lactose. When placed in a lactose-rich medium, it has been found that 20% of the cells mutated from Lac- (could not process lactose) to Lac+, meaning they could now utilize the lactose in their environment. The responses to stress are not in current DNA, but the change is made during DNA replication through recombination and the replication process itself, meaning that the adaptive mutation occurs in the current bacteria and will be inherited by the next generations because the mutation becomes part of the genetic code in the bacteria. This is particularly obvious in a study by Cairns, which demonstrated that even after moving E. coli back to a medium with minimal levels of lactose, Lac+ mutants continued to be produced as a response to the previous environment. This would not be possible if adaptive mutation was not at work because natural selection would not favor this mutation in the new environment. Although there are many genes involved in adaptive mutation, RecG, a protein, was found to have an effect on adaptive mutation. By itself, RecG was found to not necessarily lead to a mutational phenotype. However, it was found to inhibit the appearance of revertants (cells that appeared normally, as opposed to those with the mutations being studied) in wild type cells. On the other hand, RecG mutants were key to the expression of RecA-dependent mutations, which were a major portion of study in the SOS response experiments, such as the ability to utilize lactose.
Adaptive mutation was re-proposed in 1988 by John Cairns who was studying Escherichia coli that lacked the ability to metabolize lactose. He grew these bacteria in media in which lactose was the only source of energy. In doing so, he found that the rate at which the bacteria evolved the ability to metabolize lactose was many orders of magnitude higher than would be expected if the mutations were truly random. This inspired him to propose that the mutations that had occurred had been directed at those genes involved in lactose utilization.
Later support for this hypothesis came from Susan Rosenberg, then at the University of Alberta, who found that an enzyme involved in DNA recombinational repair, recBCD, was necessary for the directed mutagenesis observed by Cairns and colleagues in 1989. The directed mutagenesis hypothesis was challenged in 2002, by work showing that the phenomenon was due to general hypermutability due to selected gene amplification, followed by natural selection, and was thus a standard Darwinian process. Later research from 2007 however, concluded that amplification could not account for the adaptive mutation and that "mutants that appear during the first few days of lactose selection are true revertants that arise in a single step".
SOS response
This experiment is different from the others in one small way: this experiment is concerned with the pathways leading to an adaptive mutation while the others tested the changing environment microorganisms were exposed to. The SOS response in E. coli is a response to DNA damage that must be repaired. The normal cell cycle is put on hold and mutagenesis may begin. This means that mutations will occur to try to fix the damage. This hypermutation, or increased rate of change, response has to have some regulatory process, and some key molecules in this process are RecA, and LexA. These are proteins and act as stoplights for this and other processes. They also appear to be the main contributors to adaptive mutation in E. coli. Changes in presence of one or the other was shown to affect the SOS response, which in turn affected how the cells were able to process lactose, which should not be confused with the lactose starvation experiment. The key point to understand here is that LexA and RecA both were required for adaptive mutation to occur, and without the SOS response adaptive mutation would not be possible.
Yeast
von Borstel, in the 1970s, conducted experiments similar to the Lactose Starvation experiment with yeast, specifically Saccharomyces cerevisiae. He tested for tryptophan auxotroph revertants. A tryptophan auxotroph cannot make tryptophan for itself, but wild-type cells can and so a revertant will revert to the normal state of being able to produce tryptophan. He found that when yeast colonies were moved from a tryptophan-rich medium to a minimal one, revertants continued to appear for several days. The degree to which revertants were observed in yeast was not as high as with bacteria. Other scientists have conducted similar experiments, such as Hall who tested histidine revertants, or Steele and Jinks-Robertson who tested lysine. These experiments demonstrate how recombination and DNA replication are necessary for adaptive mutation. However, in lysine-tested cells, recombination continued to occur even without selection for it. Steele and Jinks-Robertson concluded that recombination occurred in all circumstances, adaptive or otherwise, while mutations were present only when they were beneficial and adaptive.
Although the production of mutations during selection was not as vigorous as observed with bacteria, these studies are convincing. As mentioned above, a subsequent study adds even more weight to the results with lys2. Steele and Jinks-Robertson found that LYS prototrophs due to interchromosomal recombination events also continue to arise in nondividing cells, but in this case, the production of recombinants continued whether there was selection for them or not. Thus, mutation occurred in stationary phase only when it was adaptive, but recombination occurred whether it was adaptive or not.
Delayed appearance of mutants has also been reported for Candida albicans. With long exposure to sublethal concentrations of heavy metals, colonies of resistant cells began to appear after 5–10 days and continued to appear for 1–2 weeks thereafter. These resistances could have resulted from gene amplification, although the phenotypes were stable during a short period of nonselective growth. However, revertants of two auxotrophies also appeared with similar kinetics. None of these events in Candida albicans have, as yet, been shown to be specific to the selection imposed.
References
Mutation
Non-Darwinian evolution | Adaptive mutation | Biology | 1,675 |
24,155,741 | https://en.wikipedia.org/wiki/C39H54N10O13S | {{DISPLAYTITLE:C39H54N10O13S}}
The molecular formula C39H54N10O13S (molar mass: 902.97 g/mol, exact mass: 902.3593 u) may refer to:
Amaninamide
Gamma-Amanitin
Molecular formulas | C39H54N10O13S | Physics,Chemistry | 71 |
25,648,059 | https://en.wikipedia.org/wiki/Panellus%20stipticus | Panellus stipticus, commonly known as the bitter oyster, the astringent panus, the luminescent panellus, or the stiptic fungus, is a species of fungus. It belongs in the family Mycenaceae, and the type species of the genus Panellus. A common and widely distributed species, it is found in Asia, Australia, Europe, and North America, where it grows in groups or dense overlapping clusters on the logs, stumps, and trunks of deciduous trees, especially beech, oak, and birch. During the development of the fruit bodies, the mushrooms start out as tiny white knobs, which, over a period of one to three months, develop into fan- or kidney-shaped caps that measure up to broad. The caps are orange-yellow to brownish, and attached to the decaying wood by short stubby stalks that are connected off-center or on the side of the caps. The fungus was given its current scientific name in 1879, but has been known by many names since French mycologist Jean Bulliard first described it as Agaricus stypticus in 1783. Molecular phylogenetic analysis revealed P. stipticus to have a close genetic relationship with members of the genus Mycena.
Panellus stipticus is one of several dozen species of fungi that are bioluminescent. Strains from eastern North America are typically bioluminescent, but those from the Pacific coast regions of North America and from other continents are not. The luminescence is localized to the edges of the gills and the junction of the gills with the stem and cap. Bioluminescence is also observable with mycelia grown in laboratory culture, and the growth conditions for optimal light production have been studied in detail. Several chemicals have been isolated and characterized that are believed to be responsible for light production. Genetic analysis has shown that luminescence is controlled by a single dominant allele. The luminescent glow of this and other fungi inspired the term foxfire, coined by early settlers in eastern and southern North America. Modern research has probed the potential of P. stipticus as a tool in bioremediation, because of its ability to detoxify various environmental pollutants.
Taxonomy and phylogeny
The species was first named Agaricus stypticus by the French botanist Jean Bulliard in 1783, and later sanctioned by Elias Magnus Fries under this name in 1821. Fries later changed the genus as well as the spelling of the epithet and called it Panus stipticus. The species has had an extensive taxonomic history and been shuffled to a number of genera by various authors, resulting in several synonyms: Agaricus flabelliformis (Johann Friedrich Gmelin, 1792), Pocillaria stiptica (Otto Kuntze, 1898), Rhipidium stipticum (Karl Friedrich Wilhelm Wallroth, 1833), Crepidopus stipticus (Samuel Frederick Gray, 1821), Pleurotus stipticus (Paul Kummer), Lentinus stipticus (Joseph Schröter, 1885), and Merulius stipticus (Jean-Baptiste Lamarck). It was Finnish mycologist Petter Karsten who in 1879 assigned its current name. Panellus stypticus is still used in the literature as a variant spelling.
Panellus stipticus is the type species of the genus Panellus, and, in Rolf Singer's authoritative 1986 classification of the Agaricales, it is also the type species of subgenus Panellus, an infrageneric (below the taxonomic level of genus) grouping of Panellus species characterized by the absence of cystidia on the sides of the gills. More recently, phylogenetic analyses of the sequences of their ribosomal large subunit genes have concluded that Panellus stipticus is closely related to the poroid mushroom Dictyopanus pusillus. The molecular analysis supports a previous assessment by mycologists Harold Bursdall and Orson K. Miller, who in 1975 suggested merging Dictyopanus into Panellus based on similarities in spore shape, stem structure, and the ability of dried fruit bodies to revive when moistened. Formerly grouped in the family Tricholomataceae, a wastebasket taxon of gilled mushrooms with white spores, P. stipticus is now classified in the Mycenaceae, after a large-scale phylogenetic analysis revealed "a previously unsuspected relationship between Mycena and Panellus (including Dictyopanus)".
The fungus is commonly known as the bitter oyster, the luminescent panellus, the astringent panus, or the styptic fungus. The specific epithet stipticus refers to its purported value in stopping bleeding. Etymologically, it is a Greek equivalent to the Latin word astringens, deriving from στυπτικός (styptikós), itself from the verb στύφειν (styphein), "to contract".
Description
The fungus normally exists unseen, in the form of a mass of threadlike vegetative cells called a mycelium, inhabiting rotting wood; only when suitable environmental conditions of temperature, moisture, and nutrient availability are achieved does the fungus produce the reproductive structures known as fruit bodies, or mushrooms. The cap of the fruit body is kidney- or clamshell-shaped, convex to roughly flat, with dimensions of by . The edges of the caps are scalloped with small rounded teeth, and curved slightly inward. The cap surface is dry, with a pattern of block-like areas similar to cracked dried mud; the surface is also covered with small fine hairs that give it a somewhat woolly consistency. It may have several concentric ridges or zones. Fresh fruit bodies range in color from yellowish-orange to buff to cinnamon; when dried they may be various shades of tan, brown or clay. The faded colors of dried fruit bodies tend to revive when moistened. On the underside of the cap, the gills are narrow and spaced closely together, often forked, buff-colored, and with numerous interconnecting cross-veins. Holding the cap in position is a stem that is long by thick, and has an off-center attachment to the cap, either at or near the cap side. The dull-white stem is covered with minute silk-like fibers, and is narrower at the base where it attaches to the substrate. Fruit bodies do not have any distinctive odor. The flesh is thin and tough, and dark yellow-brown to cream-colored.
Microscopic features
Various microscopic characteristics may be used to help identify the fungus from other morphologically similar species. A spore print of P. stipticus, made by depositing a large number of spores in a small area, reveals their color to be white. Viewed with a microscope, the spores are smooth-walled, elliptical to nearly allantoid (sausage-shaped), with dimensions of 3–6 by 2–3 μm. Spores are amyloid, meaning that they will absorb iodine and become bluish-black when stained with Melzer's reagent, but this staining reaction has been described as "relatively weak".
The basidia (the spore-bearing cells) are 15–20 by 2.5–3.5 μm, club-shaped, and clamped at the base. The spores are attached to the end of the basidia by four projections called sterigmata that are 1–3.5 μm long. Cystidia are hyphal cells in the hymenium that do not produce basidiospores; they also make up the surfaces of the fruit body (the pelli or "cuticles"). They are usually structurally distinct from the basidia, and their features may be used as microscopic characters to help distinguish and differentiate similar fungi. The cheilocystidia are found on the gill edge; in P. stipticus they are narrowly club-shaped, cylindrical, spindle-shaped to bifurcate at the apex. They are also thin-walled, hyaline (translucent), abundant and crowded, and measure 17–45 by 3.5–6 μm. The pleurocystidia, located on the gill face, are 17–40 by 3–4.5 μm, spindle- or club-shaped, sometimes bifurcate at the apex, thin-walled, and hyaline. They are scattered or in dense clusters, mostly embedded in hymenium, occasionally protruding up to half the width of the hymenium.
The flesh of the cap consists of a number of microscopically distinct layers of tissue. The cuticle of the cap (known as the pileipellis) is between 8–10 μm thick, and is made of a loose textura intricata, a type of tissue in which the hyphae are irregularly interwoven with distinct spaces between them. The cuticle hyphae are thick-walled to thin-walled, with scattered inconspicuous cystidia measuring 40–55 by 3.5–5.5 μm. These cystidia located in the cap (pileocystidia) are cylindrical, thin-walled, yellow in Melzer's reagent, hyaline in KOH, sometimes with amorphous dingy brown material coating the walls. Beneath the cuticle layer is a zone 54–65 μm thick, made of very loosely entwined, thin-walled hyphae, 2–3 μm in thickness, with clamps at the septa. Below this is a zone 208–221 μm in thickness, in which the densely compacted hyphae, 3–8 μm in diameter, have swollen, gelatinized walls, and often more or less a vertical orientation. This in turn is followed by a layer 520 μm in thickness, formed of loosely interwoven hyphae, 2–8 μm in width, some of which have thin walls with clamps at the septa, whilst others have somewhat thickened gelatinized walls. The flesh of the cap has a layer of upright hyphae bending into a lower layer of interwoven hyphae with diameters of 2.5–8 μm. The flesh of the gills is similar to that of the lower cap.
Similar species
Species of Crepidotus having a similar shape can be distinguished by their brown spore print, compared with the white spore print of P. stipticus. Schizophyllum commune has a densely hairy white to grayish cap and longitudinally split gill-folds on the underside. The ruddy panus mushroom (Panus rudis) is larger, has a reddish-brown cap that fades to pinkish-tan, and shows lilac tinges when young, fresh, and moist. Some Paxillus species may have a similar appearance, but they have yellow-brown spore prints.
Uses
Panellus stipticus is considered too small and bitter to be edible, but is considered nonpoisonous. Its taste has been described as acidic, acrid, or astringent. One 1992 study reported that the taste of the fruit bodies varies across the geographic range of the species. Those from eastern North America have a mildly acrid taste that takes time to develop, and cause uncomfortable drying in the mouth. In contrast, specimens from Japan, New Zealand, and Russia produce no sensation in the mouth, but cause significant constriction and a nauseating taste in the throat. The fruit bodies are reputed to have been used in traditional Chinese medicine as a styptic to staunch bleeding, and also as a "violent purgative".
Fruit body development
Fruit bodies first appear as tiny white knobs less than a cubic millimeter in size. In a day or two the knobs grow into a horizontal pyramidal mass, increasing in height as the hyphae lengthen. This is soon followed by the formation of a minute cap, and lengthening of the stem. The stem is about 1 mm long when the cap first begins to form. The hyphae that comprise the stem gradually cease to grow at their ends, and then start to branch, with many of the branches growing in a horizontal direction. This growth, indicated by the flattening and broadening out of the top of the stem, gives rise to the cap. The horizontally aligned hyphae grow vertical branches which remain more or less parallel, ultimately forming the dorsal tissue of the cap. Other similar downward-growing branches form the fertile hymenium, which can be seen when the cap is about 2 mm in diameter.The young cap is spherical and its growth is at first epinastic, its margin being curved inwards and pressed against the stem. In this way, the hymenium begins its development within a special enclosed chamber. As the hymenial surface increases and keeps pace with the growth of the dorsal tissue of the cap, the latter expands and exposes the gills. The gills are formed by the continual downward growth of some of the hyphae. The gills are exposed before the cap is completely developed, and before the spores are mature. Spores can be produced by fruit bodies as small as broad, and liberation of the spores continues until the fruit body is fully grown—a period of one month to three months, depending on the conditions of temperature and moisture. The mature spores are disseminated by the wind. When the fruit body is nearing maturity, some of the terminal portions of the hyphae of the dorsal surface of the cap separate, and as a consequence, the upper surface of the fruit body becomes granular in appearance.
The fruit body projects out horizontally from the growing surface. If the position of a log is altered after young fruit bodies with the beginnings of gills have appeared, the stems of these attempt to readjust themselves in order to place the cap in a horizontal position. The cap are sometimes zonate (marked with concentric lines that form alternating pale and darker zones); this depends on changes in the humidity of the environment, as variations in the amount of moisture will cause alternating periods of acceleration or slowing of growth.
A yellowish-brown pigment is diffused through the cytosol of the hyphae and is much deeper in color just below the cuticle of the cap. In very young fruit bodies, stems and caps are very pale buff, but soon the color of the cap deepens and becomes cinnamon. The intensity of the color appears to be dependent on light, for when fruit bodies are grown in diffuse light (temperature and humidity being constant) they are a uniform pale buff color, but in bright light they are cinnamon or tan.
Distribution, habitat, and ecology
Panellus stipticus is common in northern temperate regions of Europe, and has also been collected in Australia, New Zealand, Anatolia, Japan, and China. In North America, it is more common in the east than the west; the mushroom's northern range extends to Alaska, and it has been collected as far south as Costa Rica.
Panellus stipticus is a saprobic species, and causes a white rot. This is a form of wood decay in which the wood assumes a bleached appearance and where lignin as well as cellulose and hemicellulose is broken down by enzymes secreted by the fungus. Fruit bodies are usually found in tightly overlapping clusters on the sides of hardwood trees, on logs, stumps, and fallen branches. Although most commonly found on dead wood, it can also grow opportunistically in the wounds of living trees. In North America, its preferred hosts are oak, birch, maple, hickory, pecan, and American hornbeam, while in Europe, it is commonly found growing on oak, birch, alder, beech, hazel, chestnut, and ash. It has also been found growing on Ericia in North Africa. Although the fungus favors hardwoods, it has been reported to grow on loblolly pine and eastern white pine. Fruiting occurs September through November in Europe, the Canary Islands, and North America, although it may also sometimes be found in the spring. The fruit bodies are long-lasting and may be found year-round. It is an "early-stage" succession fungus, not typically recorded from plantations over 20 years old.
The fruit bodies are frequently attacked by slugs, which may be important agents in the dispersal of its spores. White-tailed deer are also known to consume the fungus.
Mating studies
Panellus stipticus uses a heterothallic, tetrapolar mating system: each basidiospore develops into a self-sterile mycelium which, when grown alone, remains homokaryotic (i.e., with all cells genetically identical) indefinitely. Researchers have paired collections of P. stipticus from Japan and Eastern North America, and later, collections from New Zealand and Russia. Although the separated allopatric populations differ in bioluminescence and taste, the results revealed a universal intercompatibility group over these geographical regions. In a 2001 study, Jin and colleagues also paired geographically representative collections of the fungus, but observed a reduced ability to cross between Northern Hemisphere and Oceanian collections, as well as between and within Oceanian collections.
Bioluminescence
Bioluminescence refers to the ability of certain living things in the environment to produce light by the action of enzymes. Bioluminescent fungi are widespread, and over 70 species are known (List of bioluminescent fungus species). Although the intensity of their luminescence is generally low compared to many other bioluminescent organisms, fungi glow continuously for days, so their total emission is comparable with that of most brightly luminescent organisms, such as fireflies. Luminous fungi are found growing on decaying wood, leading to the popular name of "foxfire" or "glow wood" when their glow is visible at night. The responsible oxidative enzymes—known generically as luciferases—produce light by oxidizing a pigment called a luciferin. In some areas, P. stypticus is bioluminescent, and the fruit bodies of these strains will glow in the dark when fresh or sometimes when revived in water after drying.
An early record of luminescence noted in P. stypticus was made by the American naturalist Thomas G. Gentry in 1885. Job Bicknell Ellis, reporting on the phenomenon for the Journal of Mycology, wrote:
By careful examination, the luminosity was found to proceed from the gills and not the stipe, nor from any fragment of rotten wood attached to the specimen. This phosphorescence was not observed in all specimens brought in for examination, and seemed to depend on some peculiar condition of the air, having been noticed only in specimens gathered in damp weather or just before a storm.
Canadian mycologist Buller in 1924 described the gills of P. stipticus in North America as luminescent, and noted that the fungus glows most strongly at the time of spore maturation. Bioluminescence has not been observed in European specimens, in Pacific North American collections, nor in strains collected from New Zealand, Russia, and Japan. Although a number of reports have confirmed that eastern North American strains are luminescent, non-luminescent North American strains are also known. In general, the intensity of fungal bioluminescence decreases after exposure to certain contaminants; this sensitivity is being investigated as a means to develop bioluminescence-based biosensors to test the toxicity of polluted soils. Most known luminescent fungi are in the genus Mycena or closely allied genera; this grouping of fungi—known as the "mycenoid lineage"—includes P. stipticus and three other Panellus species.
Mycelia
The mycelia of this species, grown in laboratory culture, have also been shown to be bioluminescent. Early studies demonstrated that short-wave ultraviolet light (at a wavelength of 280 nm) reversibly inhibited the luminescence of P. stypticus mycelia, while longer wavelength (366 nm) ultraviolet was stimulatory. Further, the fungus exhibited a pronounced diurnal periodicity, and maximum luminescence was noted between 6 and 9 pm, regardless as to whether the mycelial cultures were incubated in continuous light, continuous darkness, or a normal day-night cycle. The mycelia of P. stipticus grown submerged in liquid were non-luminescent, but became luminescent while growing on solid substrata. Dark-grown colonies were luminescent in the center, and light-grown colonies were brightest at the periphery. Other experiments have shown that growth temperature and pH have a significant effect on the level of bioluminescence, optimized at and pH 3–3.5. However, light had a significant effect on mycelial growth but not on bioluminescence, and the optimal light conditions for maximum bioluminescence were total darkness.
Fruit bodies
Bioluminescent tissue in the mature fruit body is restricted to the edge of the gills (as well as the cross-veins that connect them), the junction of the gills with the stem, and the inrolled cap edge. Distribution of bioluminescence along the gill edge corresponds to the position of the cheilocystidia. Less than 10% of the light emitted from both the young and mature fruit bodies is from other tissues, including the fertile hymenial area and the stem. Fruit body luminescence is highly variable between fruit bodies found on different logs in different environments.
Genetics
Using techniques of genetic complementation, Macrae paired nonluminescent monocaryons with luminescent ones, and concluded that luminosity in P. stipticus is an inherited character, and governed by a single pair of alleles in which luminosity was dominant over nonluminosity. Luminosity factors were independent of intersterility factors. In 1992, Lingle and colleagues agreed with Macrae about luminosity and stated that at least three different gene mutations could lead to the loss of luminescence. They also reported that the maximum bioluminescence was found at 525 nm, and shifted to 528 nm in deeply pigmented fruit bodies.
After intercontinental compatibility tests, Petersen and Bermudes suggested that bioluminescence and compatibility were independent since bioluminescence seemed to be geographically restricted. This suggested that the ability or potential to interbreed must have been preserved since separation of P. stypticus into geographically isolated areas.
Function
Several authors have suggested that the purpose of fungal bioluminescence is to attract arthropods to the fruit body to help disseminate spores. However, there has been no direct observation of this phenomenon. In many species, the mycelium is luminescent, but the fruit body is not, which argues against this hypothesis. Mycelial bioluminence may also function to attract animals that can potentially carry fungal spores in well-hydrated areas, as light emission from the mycelium is higher when it is hydrated. This would presumably increase the chance that spores would be deposited in an environment that is already optimal for growth. Basidiomycete mushrooms are known to be dependent on an adequate moisture supply for proper development. In species with a luminous mycelium, the mycelium would therefore have a dual function in performing the fungal translocation that permits transport of substances from the further environment back to the fruiting body, and in attracting disseminating vectors towards environments favorable for development of the species.
Chemical basis
In general, bioluminescence is caused by the action of luciferases, enzymes that produce light by the oxidation of a luciferin (a pigment). Several studies have evaluated the biochemical basis of light production in Panellus stipticus, and concluded that there is no specific fungal luciferase. The fungus was shown in 1988 to contain the sesquiterpene panal, which has a cadinene keto-aldehyde chemical structure. Later, two additional precursors were isolated, PS-A (1-O-decanoylpanal) and PS-B (1-O-dodecanoylpanal). If these compounds are treated with salt of ammonia or primary amines in the presence of iron(II), hydrogen peroxide, and a cationic surfactant, light is emitted by a chemiluminescence reaction, suggesting that panal and its derivatives are fungal luciferins, and that the chemiluminescence reaction is the cause of in vivo bioluminescence. In the fungus, the level of activity of the enzyme superoxide dismutase (SOD) appears to play a critical role in the amount of light emission. SOD quenches the effect of the superoxide (O2−) anion required in the reaction, and thus SOD activity has to be inhibited for the reaction to occur.
Bioremediation
As a white-rot fungus, Panellus stipticus contains enzymes that are able to break down lignin, a complex aromatic polymer in wood that is highly resistant to degradation by conventional enzyme systems. The major enzyme that initiates the cleavage of hydrocarbon rings is laccase, which catalyzes the addition of a hydroxyl group to phenolic compounds (polyphenols). The ring can then be opened between the two adjacent carbon atoms that bear the hydroxyl groups. White-rot fungi are being investigated scientifically for their potential use in the bioremediation of land contaminated by organic pollutants, and to convert industrial wastes rich in toxic polyphenols. Panellus stipticus has been shown to reduce the phenolic concentration of waste water produced by olive-processing plants—an environmental concern in many Mediterranean countries. In this study, a liquid culture of P. stipticus mycelia reduced the initial concentration of phenolic compounds by 42% after a 31-day incubation period. In a separate study, a P. stipticus culture was able to effectively degrade the environmental pollutant 2,7-dichlorodibenzo-p-dioxin, a polychlorinated dioxin.
See also
List of bioluminescent fungi
References
External links
Bioluminescent fungi
Fungi described in 1783
Fungi of Asia
Fungi of Australia
Fungi of Europe
Fungi of North America
Inedible fungi
Mycenaceae
Taxa named by Jean Baptiste François Pierre Bulliard
Fungus species | Panellus stipticus | Biology | 5,495 |
32,295,019 | https://en.wikipedia.org/wiki/Lafforgue%27s%20theorem | In mathematics, Lafforgue's theorem, due to Laurent Lafforgue, completes the Langlands program for general linear groups over algebraic function fields, by giving a correspondence between automorphic forms on these groups and representations of Galois groups.
The Langlands conjectures were introduced by and describe a correspondence between representations of the Weil group of an algebraic function field and representations of algebraic groups over the function field, generalizing class field theory of function fields from abelian Galois groups to non-abelian Galois groups.
Langlands conjectures for GL1
The Langlands conjectures for GL1(K) follow from (and are essentially equivalent to) class field theory. More precisely the Artin map gives a map from the idele class group to the abelianization of the Weil group.
Automorphic representations of GLn(F)
The representations of GLn(F) appearing in the Langlands correspondence are automorphic representations.
Lafforgue's theorem for GLn(F)
Here F is a global field of some positive characteristic p, and ℓ is some prime not equal to p.
Lafforgue's theorem states that there is a bijection σ between:
Equivalence classes of cuspidal representations π of GLn(F), and
Equivalence classes of irreducible ℓ-adic representations σ(π) of dimension n of the absolute Galois group of F
that preserves the L-function at every place of F.
The proof of Lafforgue's theorem involves constructing a representation σ(π) of the absolute Galois group for each cuspidal representation π. The idea of doing this is to look in the ℓ-adic cohomology of the moduli stack of shtukas of rank n that have compatible level N structures for all N. The cohomology contains subquotients of the form
π⊗σ(π)⊗σ(π)∨
which can be used to construct σ(π) from π. A major problem is that the moduli stack is not of finite type, which means that there are formidable technical difficulties in studying its cohomology.
Applications
Lafforgue's theorem implies the Ramanujan–Petersson conjecture that if an automorphic form for GLn(F) has central character of finite order, then the corresponding Hecke eigenvalues at every unramified place have absolute value 1.
Lafforgue's theorem implies the conjecture of that an irreducible finite-dimensional l-adic representation of the absolute Galois group with determinant character of finite order is pure of weight 0.
See also
Local Langlands conjectures
References
Lafforgue, Laurent (2002), "Chtoucas de Drinfeld, formule des traces d'Arthur-Selberg et correspondance de Langlands." (Drinfeld shtukas, Arthur-Selberg trace formula and Langlands correspondence) Proceedings of the International Congress of Mathematicians, Vol. I (Beijing, 2002), 383–400, Higher Ed. Press, Beijing, 2002.
Gérard Laumon (2002), "The work of Laurent Lafforgue", Proceedings of the ICM, Beijing 2002, vol. 1, 91–97,
G. Laumon (2000), "La correspondance de Langlands sur les corps de fonctions (d'après Laurent Lafforgue)" (The Langlands correspondence over function fields (according to Laurent Lafforgue)), Séminaire Bourbaki, 52e année, 1999–2000, no. 873.
External links
Lafforgue's publications
The work of Robert Langlands
Theorems in algebraic number theory
Representation theory of Lie groups
Automorphic forms
Conjectures
Class field theory
Langlands program
Theorems in representation theory | Lafforgue's theorem | Mathematics | 789 |
76,804,936 | https://en.wikipedia.org/wiki/Toka%20Diagana | Toka Diagana (also published as Tocka Diagana) is a Mauritanian-American mathematician, a professor of mathematics and chair of mathematics at the University of Alabama in Huntsville, and the editor-in-chief of the journal Nonautonomous Dynamical Systems. The topics of his research include functional analysis, stochastic processes, differential equations, dynamical systems, and operator theory.
Education and career
Diagana is originally from Kaédi, in southern Mauritania, a country in Northwest Africa. After attending a top high school in Kaédi, he went north to Tunisia for undergraduate studies at the of Tunis El Manar University. There, his interests in mathematical analysis and topology were sparked by Abdenabi Achour and Said Zarati. At the suggestion of Achour, he traveled to France for doctoral study in mathematics, at Claude Bernard University Lyon 1. He earned a diploma of advanced studies (master's degree) there in 1995, and completed his Ph.D. in 1999, under the direction of Jean-Bernard Baillon, also working in Lyon with Étienne Ghys.
After a brief stint as a secondary school teacher in Thoissey, France, Diagana came to Howard University in the US as a lecturer in 2000, and obtained an assistant professorship there in 2002. He was quickly promoted to associate professor in 2004, and then to full professor in 2007. He moved to his present position as professor and chair at the University of Alabama in Huntsville in 2018.
Contributions
Diagana founded the African Diaspora Journal of Mathematics, and is the editor-in-chief of the journal Nonautonomous Dynamical Systems.
His 13 authored and edited books include both mathematical monographs and multiple compilations of mathematics from researchers of the African diaspora.
Despite many academic publications, in a profile on Mathematically Gifted & Black, he describes his greatest accomplishment as his mentorship of eight African Americans to doctorates in mathematics, including two women, countering the historic underrepresentation of people from these groups in mathematics.
Recognition
Diagana is a 2006 recipient of the Prix Chinguitt, a Mauritanian national prize given annually for excellence in science research. He is a Fellow of the African Academy of Sciences, elected in 2009.
References
External links
Home page
Year of birth missing (living people)
Living people
Mauritian scientists
American mathematicians
African-American mathematicians
Mathematical analysts
Tunis El Manar University alumni
University of Lyon alumni
Howard University faculty
University of Alabama in Huntsville faculty | Toka Diagana | Mathematics | 516 |
54,117,828 | https://en.wikipedia.org/wiki/International%20Society%20for%20Prosthetics%20and%20Orthotics | The International Society for Prosthetics and Orthotics (ISPO) is a non-governmental organization of people working in or interested in prosthetics, orthotics, mobility and assistive devices technology.
It was founded in 1970 in Copenhagen, Denmark by a committee chaired by Knud Jansen. It currently has about 3,500 members in over 100 countries.
ISPO, in partnership with the World Health Organization (WHO) has developed the WHO Standards for Prosthetics and Orthotics that were launched in May 2017 at the 16th World Congress of the International Society of Prosthetics and Orthotics (ISPO) in Cape Town, South Africa.
ISPO is also responsible for Prosthetics and Orthotics International, an academic journal that quarterly publishes papers related to Prothetics and Orthotics.
References
External links
Prosthetics
International medical and health organizations
Non-profit organizations based in Copenhagen
1970 establishments in Denmark | International Society for Prosthetics and Orthotics | Engineering,Biology | 203 |
18,387,734 | https://en.wikipedia.org/wiki/Wood-burning%20stove | A wood-burning stove (or wood burner or log burner in the UK) is a heating or cooking appliance capable of burning wood fuel, often called solid fuel, and wood-derived biomass fuel, such as sawdust bricks. Generally the appliance consists of a solid metal (usually cast iron or steel) closed firebox, often lined by fire brick, and one or more air controls (which can be manually or automatically operated depending upon the stove). The first wood-burning stove was patented in Strasbourg in 1557. This was two centuries before the Industrial Revolution, so iron was still prohibitively expensive. The first wood-burning stoves were high-end consumer items and only gradually became used widely.
The stove is connected by ventilating stove pipe to a suitable flue, which will fill with hot combustion gases once the fuel is ignited. The chimney or flue gases must be hotter than the outside temperature to ensure combustion gases are drawn out of the fire chamber and up the chimney.
Wood burners can triple the level of harmful indoor air pollution.
In the 2010s, 61,000 premature deaths were attributable annually to ambient air pollution from residential heating with wood and coal in Europe, with an additional 10,000 attributable deaths in North America. The use of wood-burning stoves in Africa is associated with a large number of deaths each year, approximately 463,000. This high number of deaths is due to the inhalation of toxic smoke emitted by improperly vented stoves, and contains substances harmful to health. In addition, reliance on wood as an energy source also contributes to deforestation and climate change, although the emissions from wood-derived fuels are the same as emissions from natural decay.
Operation
Air supply
Keeping the air flowing correctly through a wood-burning stove is essential for safe and efficient operation of the stove. Fresh air needs to enter the firebox to provide oxygen for the fire; as the fire burns, the smoke must be allowed to rise through the stove pipe, creating negative pressure in the firebox, and exit through the chimney. To regulate air flow, there may be damper devices built into the stove, flue, and stove pipes, and there is usually an air intake adjustment to regulate combustion.
By opening or closing the dampers, air flow can be increased or decreased, which can fan the fire in the firebox, or "dampen" it by restricting airflow and reducing the flames. The dampers can usually be accessed by turning knobs or handles attached to the damper. Some stoves adjust their own airflow using mechanical or electronic thermostatic devices.
The highest heating efficiencies on closed appliances can be attained by controlling the various supplies of air to the stove (operating the air controls correctly). On modern stoves, owner's manuals provide documented procedures. Fully open air controls may lead to more heat being sent straight up the chimney rather than into the room (which reduces efficiency). The biggest problem with leaving the air controls fully open on many stoves is “overfiring”. Overfiring is caused when too much heat is generated within the fire chamber, which will lead to warping, buckling and general damage to the stove and its internal components. Different stoves have different numbers and types of air controls. More efficient models have been developed in recent years, employing catalytic combustors to burn remaining particles and gasses within the smoke before it exits the flue, resulting in more heat output, longer burn times and less harmful effect on the environment.
Modern building techniques have created more airtight homes, forcing many stove manufacturers to design their stoves to permit outside air intakes. Outside air can improve the overall efficiency of the stove as a heater by drawing cold combustion air directly from the outside instead of drawing preheated air from the room that the stove is in. Many modern stoves can optionally use an outside air intake. Many manufacturers supply the necessary parts in kit form (an Outside Air Kit, or OAK). When considering an outside air kit, it is important to know that the air must come in from below the level of the stove. For example, a basement stove may not safely use an outside air kit. This is to prevent a reversal of venting in which very hot flue gasses are exhausted through a (usually PVC) air intake pipe, which could lead to a structure fire and/or hot flue gasses being released into the structure.
Fuel
Hardwood or softwood
Firewood is usually measured and traded by volume or mass. In English-speaking countries not fully metric it is often measured in cords. A face cord is 4' x 8' x the length of the log (usually 16 to 18 inches). A full cord is 4'x4'x8'. When purchasing, cutting, or collecting firewood, it is good to be aware of the difference between hardwood and softwood. Both hardwood and softwood have similar energy contents by mass, but not by volume. In other words, a piece of hardwood would usually be heavier and have more available energy than the same sized piece of softwood. Hardwoods, derived from trees such as oak and ash, may burn at a slower rate, resulting in sustained output. Many softwoods are derived from conifers, which are fast growing and may burn at a faster rate. This is one reason why softwood pellets (for pellet stoves) are popular.
The primary advantage of hardwoods is that they tend to contain more potential energy than the same volume of a softwood, thus increasing the amount of potential heat that can be stacked into one stoveload. Hardwood tends to form and maintain a bed of hot coals, which release lower amounts of heat for a long time. Hardwoods are ideal for long, low burns, especially in stoves with a poor ability to sustain a low burn, or in mild weather when high heat output is not required.
Softwoods, in contrast, tend to burn hot and fast with little coaling. They may leave less ash than hardwoods. Softwoods are ideal for fast, hot burns. They produce excellent heat and do not fill the stove with coals, a frequent problem for those pushing their hardwood-fired stoves hard to get the maximum possible heat out of them.
Not all hardwoods have a higher potential energy content than all softwoods. Wood varies by species and even individual trees (a tree with many years of slow growth will have a higher BTU content than a tree of the same species and same size than a tree with a few years of rapid growth). Osage orange, also known as hedge, is perhaps the highest-BTU wood that is common in North America.
Many softwoods will season (dry) much more quickly than many hardwoods. For example, pine that has been cut, split, stacked and topcovered will usually be ready to burn in one year; oak may be expected to take three years under the same conditions.
Softwood mythology
Softwood is often said to be dangerous to burn because it generates more dangerous creosote than hardwood. This myth is pervasive in the North American northeast, where both types of wood are commonly available. It is not common in the northwest, where most full-time wood burners burn pine and fir exclusively.
It is possible that this myth originated with old-fashioned stoves and fireplaces. These appliances did not require seasoned wood, and frequently did not receive it. As a result, they often experienced very low flue temperatures — usually in flues that were not insulated as modern flues are. The combination of low firebox temperatures due to high moisture content in the wood and low flue temperatures due to lack of insulation led to high levels of creosote accumulation. Burning a wood that emits a lot of sparks (such as pine) in an old-fashioned fireplace or stove will lead to sparks going directly into the flue, which can lead to a dangerous chimney fire if the flue is coated in creosote.
Modern stoves which are operated properly do not cause this high level of creosote accumulation. While different wood species do contain varying levels of volatile organic compounds, the difference is inconsequential since all woods produce creosote which accumulates if burned improperly. So-called dangerous woods such as pine are in fact safer than woods such as oak, as they will burn hotter and thus help keep flue temperatures up, and their fast seasoning will help ensure that novice wood burners are burning reasonably dry wood.
Moisture content and creosote
Dry wood produces more usable heat than wet wood, since the energy isn’t being used to evaporate the water from the wood before it can burn. Freshly cut wood (known as green wood) has a high moisture content. Different wood species have different moisture contents, which also vary tree to tree. Burning fuel that is mostly water uses much of the combustion energy to evaporate the water. This results in low firebox temperatures and low flue temperatures.
Firewood with a moisture content below 20 per cent by weight can burn efficiently. This is the "free" moisture content absorbed in the wood fibers, and does not include the chemically-bound hydrogen and oxygen content. Moisture content can be reduced by outdoor air-drying ("seasoning"), for a period of several months in summer weather. Solar-powered or fuel-fired kilns can accelerate the drying process.
The most common process of removing the excess moisture is called seasoning. Seasoning by air-drying the wood can take three years or more. Wood is dried in outdoor well-ventilated covered structures, or in a kiln.
All wood will release creosote vapors when burned. Modern stoves will burn the vapors, either via direct secondary combustion or via a catalyst. Very little, if any, creosote will escape a properly operating modern stove's secondary combustion.
Creosote that does escape may still not be harmful if it leaves the wood in gaseous form. It will not condense on surfaces above 250 degrees Fahrenheit (121 °C). Modern flues are insulated to help ensure that they do not fall below this temperature during normal stove operation. Creosote accumulation can be dangerous, as it is flammable and burns hot. If a flue is coated with creosote and ignited, perhaps by a spark going up the flue, it can cause a serious chimney fire that can lead to a structure fire. This can be avoided by using modern stoves and flue standards, burning dry wood, keeping fires hot enough to maintain flue temperatures of at least 250 degrees F (121 °C) at the top of the flue, and proper chimney cleaning as needed.
Multi-fuel models
Multi-fuel stove designs are common in Europe. They burn solid fuels only, including wood, wood pellets, coal and peat. They are typically made of steel or cast iron. Some models are also boiler stoves, with an attached water tank to provide hot water, and they can also be connected to radiators to add heat to the house, though they are usually not as efficient as a dedicated wood boiler.
There are also stove models that can switch from wood fuel to oil or gas sources that are installed in the house to supply heat to a separate water boiler. Stoves that readily convert to either oil or gas in addition to wood fuel have been manufactured in North America and Europe since the early 20th century, and are still manufactured. In some models, the oil or gas may fuel the stove through a pipe connection leading to a "pot burner" in the rear of the firewood compartment in the stove.
Multi-fuel stoves are versatile, but usually perform poorly compared to a stove that is designed to burn one specific fuel as well as possible.
Catalytic and non-catalytic stoves
Modern wood stoves universally have some method of secondary combustion to burn unburned gasses for greatly improved efficiency and emissions. One common method is via a catalyst.
A catalytic wood stove will re-burn the gasses from the firebox in a catalyst- a matrix of steel or ceramic plated with a catalyst that allows combustion of these gasses at much lower temperatures than would ordinarily be possible. This is why among modern stoves, catalytic models tend to be much better at achieving low, even heat output, which is desirable in warmer weather.
Modern non-catalytic wood stoves will also reburn the gasses from the firebox, but require a much higher temperature for the secondary combustion. No catalyst is required. These models lose a large amount of efficiency at low burn rates, as they cannot maintain secondary combustion, but can be very efficient at higher temperatures when that comes into effect.
There also exist hybrid stoves that employ both catalytic and non-catalytic secondary combustion.
Stoves that do not employ any secondary combustion still exist, but are markedly less efficient and more polluting since unburnt products are left to leave via the flue.
Pyrolyzing stoves
In a conventional stove, when wood is added to a hot fire, a process of pyrolysis or destructive distillation begins. Gases (or volatiles) are evolved which are burned above the solid fuel. These are the two distinct processes going on in most solid fuel appliances. In obsolete stoves without secondary combustion, air had to be admitted both below and above the fuel to attempt to increase combustion and efficiency. The correct balance was difficult to achieve in practice, and many obsolete wood-burning stoves only admitted air above the fuel as a simplification. Often the volatiles were not completely burned, resulting in energy loss, chimney tarring, and atmospheric pollution.
To overcome this, the pyrolyzing stove was developed. The two processes go on in separate parts of the stove with separately controlled air supplies. Most stoves designed to burn wood pellets fall into this category.
Most pyrolyzing stoves regulate both fuel and air supply as opposed to controlling combustion of a mass of fuel by simple air regulation as in traditional stoves.
The pelleted fuel is typically introduced into the pyrolyzing chamber with a screw conveyor. This leads to better and more efficient combustion of the fuel.
The technology is not actually new; it has been used for decades in industrial coal-fired boilers intended to burn coal with high volatile content.
Safety and pollution considerations
Safety
Correct air flow and ventilation are also critical to efficient and safe wood burning. Specific requirements will be laid down by the stove manufacturer. Legal requirements for new installations in the UK can be found in Building Regulations Approved Document J, Section 2, Table 1 "Air Supply to solid fuel appliances".
The safe operation of a wood-burning stove requires regular maintenance such as emptying ash pans (containers) beneath the wood grate. Routine cleaning of the stove pipes and chimney is also needed to prevent chimney fires. Creosote and soot gradually build up in stovepipes and chimneys. This could damage the chimney and spread fire to the surrounding structure, especially the roof. When soot blocks the airflow through the stove pipes or chimney, smoke can build up in the stove pipes and in the house.
The basic principle of controlling combustion by reducing the air supply means that very often there is a reduction zone/conditions within the stove. This means that carbon dioxide is often "reduced" to carbon monoxide, which is highly poisonous and must not be allowed to escape into the home. This can occur if the stove or chimney has not been cleaned or there is insufficient ventilation. Carbon monoxide detectors or alarms should always be installed according to manufacturers' recommendations where a wood stove is in use. Not all smoke detectors detect carbon monoxide.
Fuel accelerants such as coal, grease, oil, gasoline, kerosene, plastics, and so on, also must never be added to firewood in a wood stove, since the flames produced may easily overwhelm the wood compartment and stove pipes and create a house fire.
UK smoke control areas
Under the United Kingdom's Clean Air Act, local authorities may declare the whole or part of the district of the authority to be a smoke control area. It is an offence to emit smoke from a chimney of a building, from a furnace or from any fixed boiler if located in a designated smoke control area. It is also an offence to acquire an "unauthorized fuel" for use within a smoke control area unless it is used in an "exempt" appliance ("exempted" from the controls which generally apply in the smoke control area). The current maximum level of fine is £1,000 for each offence.
In order to comply with the Clean Air Act in "smoke control areas", an exempt appliance or fuel must be used.
US pollution control requirements
The United States Clean Air Act requires that wood stoves be certified by the Environmental Protection Agency (EPA).
However, the EPA had no mandatory emission limits for pellet stoves, indoor or outdoor wood boilers, masonry stoves and certain types of wood stoves that are exempt from EPA regulation. EPA developed new regulations which began to come into effect in 2015, establishing mandatory emission limits for almost all wood-burning appliances (fireplaces, chimeneas, and some other special appliances will still be exempt).
In 2019, EPA's mandatory smoke emission limit for wood stoves in 2019 was 4.5 grams of smoke per hour (g/h) under Step 1 of the revised standards of performance for wood burning room heaters. Washington State has also had requirements of a maximum of 4.5 grams per hour.
The New Source Performance Standards (NSPS) for Residential Wood Heaters, which came into effect on May 15, 2020.The EPA initiated wood stove emissions standards in 1988 to mitigate air pollution, setting the initial limits at 7.5 grams per hour for non-catalytic and 4.1 grams for catalytic stoves. These regulations have been refined over time, notably in 2015 with a phased approach to lower emissions. The first phase capped emissions at 4.5 grams per hour, and the second phase further reduced this limit to either 2.0 or 2.5 grams per hour, based on the testing technique employed.
The latest "Phase IV" or "Step 2 Standards" demand stricter criteria for wood stoves, notably shifting from crib wood to cord wood for testing. Previously, the EPA utilized crib wood, consistent in size and arrangement, for reliable testing burns. However, this method didn't mirror actual stove usage in homes, where the more variable cord wood is standard. This change aims for more realistic emissions testing, acknowledging the diversity in wood size, moisture, and type used in residences.
Justa stoves, rocket stoves and haybox stoves
In some places, such as the Caribbean, Central America and South America, many houses have wood-burning stoves that are used indoors without any means of proper ventilation. Smoke stays in the house, where it is breathed in by the residents, harming their health. Nearly two million people are killed each year by indoor air pollution caused by open-fire cooking, mostly women and children, according to the World Health Organization (WHO). The cutting of large amounts of firewood also endangers local forests and ecosystems.
Non-governmental organizations (NGOs) such as Rotary International are actively assisting homeowners in constructing more fuel-efficient and safe wood-burning stoves. One design is called the Justa stove, Just stove, Ecostove, or La Estufa Justa. Justa stoves are made out of such materials as adobe, cement, and pumice, with chimneys. Other wood-burning stoves types are also being introduced to these communities, such as rocket stoves and haybox stoves. A rocket stove is up to 30% more fuel efficient than a Justa stove, but a small portable rocket stove (for cooking) does not have a chimney and is suitable for outdoor use only. Bigger rocket stoves are connected to chimney or flue-exhaust pipe. The haybox stove is another outdoor wood-burning stove. Haybox stoves use straw, wool, or foam as an insulator, reducing fuel use by up to 70%.
Use in Europe
Italy is one of the biggest markets for pellet-burning stoves in Europe, having around 30% of all homes using wood for some heat. This means about 5 million homes have a wood fueled stove or cooker.
It has been claimed that, in the UK, domestic wood burning has become the single biggest source of small particle air pollution. However, UK Gov. (DEFRA) statistics do not support this claim with road transport and industrial processes both being larger polluters.
Types
Franklin stove, originally invented by Benjamin Franklin, is a more efficient type of wood-burning fireplace. It was finicky and never caught on, but many stoves continue to be referred to as "Franklin" stoves.
Carl Johan Cronstedt is reported to have increased efficiency of wood-burning stoves by a factor of eight in the mid-18th century.
Wolfgang Schroeter invented the first wood-burning stove with a cast iron frame and glass door. This allowed the user to see the fire burning inside the stove.
A fireplace insert converts a wood-burning fireplace to a wood-burning stove. A fireplace insert is a self-contained unit that rests inside the existing fireplace and chimney. They produce less smoke and require less wood than a traditional fireplace. Fireplace inserts come in different sizes for large or small homes.
Down draft or cross draft gasification stoves, i.e. Dunsley Yorkshire, Welkom 600, Avalon Arbor™ wood stove, XEOOS.
Boiler stoves provide hot water as well as space heating. A backboiler can be an optional insert added to the back of the firebox, or a wrap-around water jacket that is an integral to the stove's structure. The choice determines how much of the stove's output goes to space heating as opposed to heating water.
Rocket mass heaters are a type of fuel-efficient stove, named in the 1970s, but dating back millennia in concept. A super-hot chimney above the fire draws the flames sideways and up, blending hot fuel and air into a quick, hot, clean-burning fire that takes little wood, leaves little residue, and has many uses.
See also
Chimenea
Air-tight stove
BioLite
Bukhari, traditional Indian wood stove
Cook stove
Kitchen stove
List of stoves
Masonry stove
Outdoor wood-fired boiler
Pellet stove
Portable stove
Pot-bellied stove
Red Cross stove
Rocket stove
Top-lit updraft gasifier
Notes
References
Boilers
Residential heating appliances
Stoves | Wood-burning stove | Chemistry | 4,680 |
1,399,190 | https://en.wikipedia.org/wiki/Assisted%20reproductive%20technology | Assisted reproductive technology (ART) includes medical procedures used primarily to address infertility. This subject involves procedures such as in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), and cryopreservation of gametes and embryos, and the use of fertility medication. When used to address infertility, ART may also be referred to as fertility treatment. ART mainly belongs to the field of reproductive endocrinology and infertility. Some forms of ART may be used with regard to fertile couples for genetic purpose (see preimplantation genetic diagnosis). ART may also be used in surrogacy arrangements, although not all surrogacy arrangements involve ART.
The existence of sterility will not always require ART to be the first option to consider, as there are occasions when its cause is a mild disorder that can be solved with more conventional treatments or with behaviors based on promoting health and reproductive habits.
Procedures
General
With ART, the process of sexual intercourse is bypassed and fertilization of the oocytes occurs in the laboratory environment (i.e., in vitro fertilization).
In the US, the Centers for Disease Control and Prevention (CDC) defines ART to include "all fertility treatments in which both eggs and sperm are handled. In general, ART procedures involve surgically removing eggs from a woman's ovaries, combining them with sperm in the laboratory, and returning them to the woman's body or donating them to another woman." According to CDC, "they do not include treatments in which only sperm are handled (i.e., intrauterine—or artificial—insemination) or procedures in which a woman takes medicine only to stimulate egg production without the intention of having eggs retrieved."
In Europe, ART also excludes artificial insemination and includes only procedures where oocytes are handled.
The World Health Organization (WHO), also defines ART this way.
Ovulation induction
Ovulation induction is usually used in the sense of stimulation of the development of ovarian follicles by fertility medication to reverse anovulation or oligoovulation. These medications are given by injection for 8 to 14 days. A health care provider closely monitors the development of the eggs using transvaginal ultrasound and blood tests to assess follicle growth and estrogen production by the ovaries. When follicles have reached an adequate size and the eggs are mature enough, an injection of the hormone hCG initiates the ovulation process. Egg retrieval should occur 36 hours before ovulation.
In vitro fertilization
In vitro fertilization is the technique of letting fertilization of the male and female gametes (sperm and egg) occur outside the female body.
Techniques usually used in in vitro fertilization include:
Transvaginal ovum retrieval (OVR) is the process whereby a small needle is inserted through the back of the vagina and guided via ultrasound into the ovarian follicles to collect the fluid that contains the eggs.
Embryo transfer is the step in the process whereby one or several embryos are placed into the uterus of the female with the intent to establish a pregnancy.
Less commonly used techniques in in vitro fertilization are:
Assisted zona hatching (AZH) is performed shortly before the embryo is transferred to the uterus. A small opening is made in the outer layer surrounding the egg in order to help the embryo hatch out and aid in the implantation process of the growing embryo.
Intracytoplasmic sperm injection (ICSI) is beneficial in the case of male factor infertility where sperm counts are very low or failed fertilization occurred with previous IVF attempt(s). The ICSI procedure involves a single sperm carefully injected into the center of an egg using a microneedle. With ICSI, only one sperm per egg is needed. Without ICSI, you need between 50,000 and 100,000. This method is also sometimes employed when donor sperm is used.
Autologous endometrial coculture is a possible treatment for patients who have failed previous IVF attempts or who have poor embryo quality. The patient's fertilized eggs are placed on top of a layer of cells from the patient's own uterine lining, creating a more natural environment for embryo development.
In zygote intrafallopian transfer (ZIFT), egg cells are removed from the woman's ovaries and fertilized in the laboratory; the resulting zygote is then placed into the fallopian tube.
Cytoplasmic transfer is the technique in which the contents of a fertile egg from a donor are injected into the infertile egg of the patient along with the sperm.
Egg donors are resources for women with no eggs due to surgery, chemotherapy, or genetic causes; or with poor egg quality, previously unsuccessful IVF cycles or advanced maternal age. In the egg donor process, eggs are retrieved from a donor's ovaries, fertilized in the laboratory with the sperm from the recipient's partner, and the resulting healthy embryos are returned to the recipient's uterus.
Sperm donation may provide the source for the sperm used in IVF procedures where the male partner produces no sperm or has an inheritable disease, or where the woman being treated has no male partner.
Preimplantation genetic diagnosis (PGD) involves the use of genetic screening mechanisms such as fluorescent in-situ hybridization (FISH) or comparative genomic hybridization (CGH) to help identify genetically abnormal embryos and improve healthy outcomes.
Embryo splitting can be used for twinning to increase the number of available embryos.
Pre-implantation genetic diagnosis
A pre-implantation genetic diagnosis procedure may be conducted on embryos prior to implantation (as a form of embryo profiling), and sometimes even of oocytes prior to fertilization. PGD is considered in a similar fashion to prenatal diagnosis. PGD is an adjunct to ART procedures, and requires in vitro fertilization to obtain oocytes or embryos for evaluation. Embryos are generally obtained through blastomere or blastocyst biopsy. The latter technique has proved to be less deleterious for the embryo, therefore it is advisable to perform the biopsy around day 5 or 6 of development. Sex selection is the attempt to control the sex of offspring to achieve a desired sex in case of X chromosome linked diseases. It can be accomplished in several ways, both pre- and post-implantation of an embryo, as well as at birth. Pre-implantation techniques include PGD, but also sperm sorting.
Others
Other assisted reproduction techniques include:
Mitochondrial replacement therapy (MRT, sometimes called mitochondrial donation) is the replacement of mitochondria in one or more cells to prevent or ameliorate disease. MRT originated as a special form of IVF in which some or all of the future baby's mitochondrial DNA comes from a third party. This technique is used in cases when mothers carry genes for mitochondrial diseases. The therapy is approved for use in the United Kingdom.
In gamete intrafallopian transfer (GIFT), a mixture of sperm and eggs is placed directly into a woman's fallopian tubes using laparoscopy following a transvaginal ovum retrieval.
Reproductive surgery, treating e.g. fallopian tube obstruction and vas deferens obstruction, or reversing a vasectomy by a reverse vasectomy. In surgical sperm retrieval (SSR), the reproductive urologist obtains sperm from the vas deferens, epididymis or directly from the testis in a short outpatient procedure.
By cryopreservation, eggs, sperm and reproductive tissue can be preserved for later IVF.
Risks
The majority of IVF-conceived infants do not have birth defects.
However, some studies have suggested that assisted reproductive technology is associated with an increased risk of birth defects.
Artificial reproductive technology is becoming more available. Early studies suggest that there could be an increased risk for medical complications with both the mother and baby. Some of these include low birth weight, placental insufficiency, chromosomal disorders, preterm deliveries, gestational diabetes, and pre-eclampsia (Aiken and Brockelsby).
In the largest U.S. study, which used data from a statewide registry of birth defects,
6.2% of IVF-conceived children had major defects, as compared with 4.4% of naturally conceived children matched for maternal age and other factors (odds ratio, 1.3; 95% confidence interval, 1.00 to 1.67). ART carries with it a risk for heterotopic pregnancy (simultaneous intrauterine and extrauterine pregnancy).
The main risks are:
Genetic disorders
Low birth weight. In IVF and ICSI, a risk factor is the decreased expression of proteins in energy metabolism; Ferritin light chain and ATP5A1.
Preterm birth. Low birth weight and preterm birth are strongly associated with many health problems, such as visual impairment and cerebral palsy. Children born after IVF are roughly twice as likely to have cerebral palsy.
Sperm donation is an exception, with a birth defect rate of almost a fifth compared to the general population. It may be explained by that sperm banks accept only people with high sperm count.
Germ cells of the mouse normally have a frequency of spontaneous point mutations that is 5 to 10-fold lower than that in somatic cells from the same individual. This low frequency in the germline leads to embryos that have a low frequency of point mutations in the next generation. No significant differences were observed in the frequency or spectrum of mutations between naturally conceived fetuses and assisted-conception fetuses. This suggests that with respect to the maintenance of genetic integrity assisted conception is safe.
Current data indicate little or no increased risk for postpartum depression among women who use ART.
Study results indicate that ART can affect both women and men's sexual health negatively.
Usage of assisted reproductive technology including ovarian stimulation and in vitro fertilization have been associated with an increased overall risk of childhood cancer in the offspring, which may be caused by the same original disease or condition that caused the infertility or subfertility in the mother or father.
That said, In a landmark paper by Jacques Balayla et al. it was determined that infants born after ART have similar neurodevelopment than infants born after natural conception.
ART may also pose risks to the mother. A large US database study compared pregnancy outcomes among 106,000 assisted conception pregnancies with 34 million natural conception pregnancies. It found that assisted conception pregnancies were associated with an increased risk of cardiovascular diseases, including acute kidney injury and arrhythmia. Assisted conception pregnancies were also associated with a higher risk of caesarean delivery and premature birth.
In theory, ART can solve almost all reproductive problems, except for severe pathology or the absence of a uterus (or womb), using specific gamete or embryo donation techniques. However, this does not mean that all women can be treated with assisted reproductive techniques, or that all women who are treated will achieve pregnancy.
Usage
As a result of the 1992 Fertility Clinic Success Rate and Certification Act, the CDC is required to publish the annual ART success rates at U.S. fertility clinics. Assisted reproductive technology procedures performed in the U.S. has over than doubled over the last 10 years, with 140,000 procedures in 2006, resulting in 55,000 births.
In Australia, 3.1% of births in the late 2000's are a result of ART.
The most common reasons for discontinuation of fertility treatment have been estimated to be: postponement of treatment (39%), physical and psychological burden (19%), psychological burden (14%), physical burden (6.32%), relational and personal problems (17%), personal reasons (9%), relational problems (9%), treatment rejection (13%) and organizational (12%) and clinic (8%) problems.
By country
United States
Many Americans do not have insurance coverage for fertility investigations and treatments. Many states are starting to mandate coverage, and the rate of use is 278% higher in states with complete coverage.
There are some health insurance companies that cover diagnosis of infertility, but frequently once diagnosed will not cover any treatment costs.
Approximate treatment/diagnosis costs in the United States, with inflation, as of (US$):
Initial workup: hysteroscopy, hysterosalpingogram, blood tests ~$
Sonohysterogram (SHG) ~ $–$
Clomiphene citrate cycle ~ $–$
IVF cycle ~ $–$
Use of a surrogate mother to carry the child – dependent on arrangements
Another way to look at costs is to determine the expected cost of establishing a pregnancy. Thus, if a clomiphene treatment has a chance to establish a pregnancy in 8% of cycles and costs $, the expected cost is $ to establish a pregnancy, compared to an IVF cycle (cycle fecundity 40%) with a corresponding expected cost of $ ($ × 40%).
For the community as a whole, the cost of IVF on average pays back by 700% by tax from future employment by the conceived human being.
European Union
In Europe, 157,500 children were born using assisted reproductive technology in 2015, according to the European Society of Human Reproduction and Embryology (ESHRE). But there are major differences in legislation across the Old Continent.
A European directive fixes standards concerning the use of human tissue and cells, but all ethical and legal questions on ART remain the prerogative of EU member states.
Across Europe, the legal criteria per availability vary somewhat. In 11 countries all women may benefit; in 8 others only heterosexual couples are concerned; in 7 only single women; and in 2 (Austria and Germany) only lesbian couples.
Spain was the first European country to open ART to all women, in 1977, the year the first sperm bank was opened there. In France, the right to ART is accorded to all women since 2019. In the last 15 years, legislation has evolved quickly. For example, Portugal made ART available in 2006 with conditions very similar to those in France, before amending the law in 2016 to allow lesbian couples and single women to benefit. Italy clarified its uncertain legal situation in 2004 by adopting Europe's strictest laws: ART is only available to heterosexual couples, married or otherwise, and sperm donation is prohibited.
Today, 21 countries provide partial public funding for ART treatment. The seven others, which do not, are Ireland, Cyprus, Estonia, Latvia, Luxembourg, Malta, and Romania.
Such subsidies are subject to conditions, however. In Belgium, a fixed payment of €1,073 is made for each full cycle of the IVF process. The woman must be aged under 43 and may not carry out more than six cycles of ART. There is also a limit on the number of transferable embryos, which varies according to age and the number of cycles completed.
In France, ART is subsidized in full by national health insurance for women up to age 43, with limits of 4 attempts at IVF and 6 at artificial insemination.
Germany tightened its conditions for public funding in 2004, which caused a sharp drop in the number of ART cycles carried out, from more than 102,000 in 2003 to fewer than 57,000 the following year. Since then the figure has remained stable.
17 countries limit access to ART according to the age of the woman. 10 countries have established an upper age limit, varying from 40 (Finland, Netherlands) to 50 (including Spain, Greece and Estonia).
Since 1994, France is one of a number of countries (including Germany, Spain, and the UK) which use the somewhat vague notion of "natural age of procreation". In 2017, the steering council of France's Agency of Biomedicine established an age limit of 43 for women using ART.
10 countries have no age limit for ART. These include Austria, Hungary, Italy and Poland.
Most European countries allow donations of gametes by third parties. But the situations vary depending on whether sperm or eggs are concerned. Sperm donations are authorized in 20 EU member states; in 11 of them anonymity is allowed. Egg donations are possible in 17 states, including 8 under anonymous conditions.
On 12 April, the Council of Europe adopted a recommendation which encourages an end to anonymity. In the UK, anonymous sperm donations ended in 2005 and children have access to the identity of the donor when they reach adulthood.
In France, the principle of anonymous donations of sperm or embryos is maintained in the law of bioethics of 2011, but a new bill under discussion may change the situation.
United Kingdom
In the United Kingdom, all patients have the right to preliminary testing, provided free of charge by the National Health Service (NHS). However, treatment is not widely available on the NHS and there can be long waiting lists. Many patients therefore pay for immediate treatment within the NHS or seek help from private clinics.
In 2013, the National Institute for Health and Care Excellence (NICE) published new guidelines about who should have access to IVF treatment on the NHS in England and Wales.
The guidelines say women aged between 40 and 42 should be offered one cycle of IVF on the NHS if they have never had IVF treatment before, have no evidence of low ovarian reserve (this is when eggs in the ovary are low in number, or low in quality), and have been informed of the additional implications of IVF and pregnancy at this age. However, if tests show IVF is the only treatment likely to help them get pregnant, women should be referred for IVF straight away.
This policy is often modified by local Clinical Commissioning Groups, in a fairly blatant breach of the NHS Constitution for England which provides that patients have the right to drugs and treatments that have been recommended by NICE for use in the NHS. For example, the Cheshire, Merseyside and West Lancashire Clinical Commissioning Group insists on additional conditions:
The person undergoing treatment must have commenced treatment before her 40th birthday;
The person undergoing treatment must have a BMI of between 19 and 29;
Neither partner must have any living children, from either the current or previous relationships. This includes adopted as well as biological children; and,
Sub-fertility must not be the direct result of a sterilisation procedure in either partner (this does not include conditions where sterilisation occurs as a result of another medical problem). Couples who have undertaken a reversal of their sterilisation procedure are not eligible for treatment.
Canada
Some treatments are covered by OHIP (public health insurance) in Ontario and others are not. Women with bilaterally blocked fallopian tubes and are under the age of 40 have treatment covered but are still required to pay test fees (around CA$3,000–4,000). Coverage varies in other provinces. Most other patients are required to pay for treatments themselves.
Israel
Israel's national health insurance, which is mandatory for all Israeli citizens, covers nearly all fertility treatments. IVF costs are fully subsidized up to the birth of two children for all Israeli women, including single women and lesbian couples. Embryo transfers for purposes of gestational surrogacy are also covered.
Germany
On 27 January 2009, the Federal Constitutional Court ruled that it is unconstitutional, that the health insurance companies have to bear only 50% of the cost for IVF. On 2 March 2012, the Federal Council has approved a draft law of some federal states, which provides that the federal government provides a subsidy of 25% to the cost. Thus, the share of costs borne for the pair would drop to just 25%. Since July 2017, assisted reproductive technology is also allowed for married lesbian couples, as German parliament allowed same-sex marriages in Germany.
France
In July 2020, the French Parliament allowed assisted reproductive technology also for lesbian couples and single women.
Cuba
Cuban sources mention that assisted reproduction is completely legal and free in the country.
India
The Government of India has notified the Surrogacy (Regulation) Act 2021 and the Assisted Reproductive Technology (Regulation) Act 2021 to regulate the practice of ART. Prior to that, the National Guidelines for Accreditation, Supervision and Regulation of ART Clinics in India published by the Ministry for Health and Family Welfare, Government of India in the year 2005 was governing the field. Indian law recognises the right of a single woman, who is a major, to have children through ART.
Society and culture
Ethics
Some couples may find it difficult to stop treatment despite very bad prognoses, resulting in futile therapies. This has the potential to give ART providers a difficult decision of whether to continue or refuse treatment.
Some assisted reproductive technologies have the potential to be harmful to both the mother and the child, posing a psychological or physical health risk, which may affect the ongoing use of these treatments.
In Israel, there is research supporting using ART, including recycled lab materials from the IVF process, to help women work through some of these mixed emotions.
Fictional representation
Films and other fiction depicting emotional struggles of assisted reproductive technology have had an upswing in the latter part of the 2000s decade, although the techniques have been available for decades. As ART becomes more utilized, the number of people that can relate to it by personal experience in one way or another is growing.
For specific examples, refer to the fiction sections in individual subarticles, e.g. surrogacy, sperm donation and fertility clinic.
In addition, reproduction and pregnancy in speculative fiction has been present for many decades.
Historical facts
25 July 1978, Louise Brown was born; this was the first successful birth of a child after IVF treatment. The procedure took place at Dr Kershaw's Cottage Hospital (now Dr Kershaw's Hospice) in Royton, Oldham, England. Patrick Steptoe (gynaecologist) and Robert Edwards (physiologist) worked together to develop the IVF technique. Steptoe described a new method of egg extraction and Edwards were carrying out a way to fertilise eggs in the lab. Robert G. Edwards was awarded the Nobel Prize in Physiology or Medicine in 2010, but not Steptoe because the Nobel Prize is not awarded posthumously.
The first successful birth by ICSI (intracytoplasmic sperm injection) took place on 14 January 1992. The technique was developed by Gianpiero D. Palermo at the Vrije Universiteit Brussel, in the Center for Reproductive Medicine in Brussels. Actually, the discovery was made by a mistake when a spermatozoid was put into the cytoplasm.
See also
Artificial uterus
Artificial insemination
Fertility fraud
Human cloning
Ova bank
Sperm bank
Sperm donation
Spontaneous conception, the unassisted conception of a subsequent child after prior use of assisted reproductive technology
Egg donation
Ralph L. Brinster
Religious response to ART
Repository for Germinal Choice
References
External links
Centers for Disease Control and Prevention (CDC), Assisted Reproductive Technology
Applied genetics
Biotechnology
Bioethics
Fertility medicine
Genetic engineering
Human reproduction
Ideologies
Liberalism
Medical ethics
Obstetrical procedures
Reproductive rights
Social philosophy
Social theories
Transhumanism | Assisted reproductive technology | Chemistry,Technology,Engineering,Biology | 4,799 |
5,664,123 | https://en.wikipedia.org/wiki/Immunoglobulin%20superfamily | The immunoglobulin superfamily (IgSF) is a large protein superfamily of cell surface and soluble proteins that are involved in the recognition, binding, or adhesion processes of cells. Molecules are categorized as members of this superfamily based on shared structural features with immunoglobulins (also known as antibodies); they all possess a domain known as an immunoglobulin domain or fold. Members of the IgSF include cell surface antigen receptors, co-receptors and co-stimulatory molecules of the immune system, molecules involved in antigen presentation to lymphocytes, cell adhesion molecules, certain cytokine receptors and intracellular muscle proteins. They are commonly associated with roles in the immune system. Otherwise, the sperm-specific protein IZUMO1, a member of the immunoglobulin superfamily, has also been identified as the only sperm membrane protein essential for sperm-egg fusion.
Immunoglobulin domains
Proteins of the IgSF possess a structural domain known as an immunoglobulin (Ig) domain. Ig domains are named after the immunoglobulin molecules. They contain about 70-110 amino acids and are categorized according to their size and function. Ig-domains possess a characteristic Ig-fold, which has a sandwich-like structure formed by two sheets of antiparallel beta strands. Interactions between hydrophobic amino acids on the inner side of the sandwich and highly conserved disulfide bonds formed between cysteine residues in the B and F strands, stabilize the Ig-fold.
Classification
The Ig like domains can be classified as IgV, IgC1, IgC2, or IgI.
Most Ig domains are either variable (IgV) or constant (IgC).
IgV: IgV domains with 9 beta strands are generally longer than IgC domains with 7 beta strands.
IgC1 and IgC2: Ig domains of some members of the IgSF resemble IgV domains in the amino acid sequence, yet are similar in size to IgC domains. These are called IgC2 domains, while standard IgC domains are called IgC1 domains.
IgI: Other Ig domains exist that are called intermediate (I) domains.
Members
The Ig domain was reported to be the most populous family of proteins in the human genome with 765 members identified. Members of the family can be found even in the bodies of animals with a simple physiological structure such as poriferan sponges. They have also been found in bacteria, where their presence is likely to be due to divergence from a shared ancestor of eukaryotic immunoglobulin superfamily domains.
References
External links
Transmembrane human proteins from immunoglobulin superfamily classified as receptors, ligands and adhesion proteins
Immunoglobulin domain in SUPERFAMILY
Receptors
Immunology
Protein superfamilies | Immunoglobulin superfamily | Chemistry,Biology | 609 |
73,916,998 | https://en.wikipedia.org/wiki/Arash%20Ghorbani-Choghamarani | Arash Ghorbani-Choghamarani (born 23 September 1979) is an Iranian chemist and Professor of Chemistry at Bu-Ali Sina University. He is also Deputy of Research and Technology at this university since November 2021.
Ghorbani-Choghamarani is among the most-cited Iranian researchers and is known for his works on organic chemistry, nanochemistry, heterogeneous catalysis, heterocyclic compounds and organic synthesis.
Previously He was professor and Deputy of Education at Ilam University.
Ghorbani-Choghamarani is a winner of Ilam Province Book of the Year for his book Drug Delivery Systems and Their Effectiveness Through Nanotechnology.
Books
New Discussions on Nanocatalysts in Organic Chemistry, Ilam: Ilam University Press 2018, ISBN 9786006184395
Drug Delivery Systems and Their Effectiveness Through Nanotechnology, Ilam: Havar 2019, ISBN 9786008473855
References
Living people
1979 births
Iranian nanotechnologists
Iranian organic chemists
Academic staff of Bu-Ali Sina University
Academic staff of Ilam University
Bu-Ali Sina University alumni | Arash Ghorbani-Choghamarani | Chemistry | 238 |
55,419,455 | https://en.wikipedia.org/wiki/Czapek%20medium | Czapek medium, also called Czapek's agar (CZA) or Czapek-Dox medium, is a growth medium for propagating fungi and other organisms in a laboratory. It was named after its inventors, Czech botanist Friedrich Johann Franz Czapek (May 16, 1868 – July 31, 1921) and American chemist Arthur Wayland Dox (September 19, 1882 – 1954). It was developed to grow Aspergillus niger and Penicillium camemberti. It works well for many saprophytic fungi and soil bacteria such as species of Aspergillus, Candida, Penicillium, and Paecilomyces.
Friedrich Czapek's original recipe is as follows:
1000 g distilled water
30 g cane sugar – energy source and sole source of carbon
1 g dipotassium phosphate – buffering agent
0.5 g magnesium sulfate – source of cations
0.5 g potassium chloride – source of essential ions
0.01 g iron sulfate – source of cations
Arthur Wayland Dox added 2 g of sodium nitrate in his version, to provide a sole source of nitrogen that is inorganic. This makes the medium a selective growth medium as only organisms that can use inorganic nitrogen can grow. Czapek and Dox did not add agar but many recipes add 15 g to make a solid medium.
References
External links
Czapek Medium recipe
Czapek solution agar recipe
Czapek's Agar recipe
Czapek-Dox Agar
Microbiological media
Cell culture media | Czapek medium | Biology | 335 |
2,219,115 | https://en.wikipedia.org/wiki/Deficits%20in%20attention%2C%20motor%20control%20and%20perception | DAMP (deficits in attention, motor control, and perception) is a psychiatric concept conceived by Christopher Gillberg defined by the presence of five properties: problems of attention, gross and fine motor skills, perceptual deficits, and speech-language impairments. While routinely diagnosed in Scandinavian countries, the diagnosis has been rejected in the rest of the world. Minor cases of DAMP are roughly defined as a combination of developmental coordination disorder (DCD) and a pervading attention deficit.
DAMP is similar to minimal brain dysfunction (MBD), a concept that was formulated in the 1960s, and which has since been recognised as attention deficit hyperactivity disorder. Both concepts are related to certain psychiatric conditions, such as hyperactivity. The concept of MBD was strongly criticized by Sir Michael Rutter [Gillberg, 2003, p. 904] and several other researchers, and this led to its abandonment in the 1980s. At the same time, research showed that something similar was needed. One alternative concept was attention-deficit hyperactivity disorder (ADHD). Gillberg proposed another alternative: DAMP. Gillberg's concept was formulated in the early 1980s, and the term itself was introduced in a paper that Gillberg published in 1986 (see Gillberg [1986]). DAMP is essentially MBD without the etiological assumptions.)
The concept of DAMP met with considerable criticism. For example, Sir Michael Rutter stated that the concept of DAMP (unlike ADHD) was "muddled" and "lacks both internal coherence and external discriminative validity ... it has no demonstrated treatment or prognostic implications"; he concluded that the concept should be abandoned. Another example is the criticism of Per-Anders Rydelius, Professor of Child Psychiatry at the Karolinska Institute, who argued that the definition of DAMP was too vague: "the borderline between DAMP and conduct disorders [is] unclear ... the borderline between DAMP and ADHD [is] unclear"; he concluded that "the concept is in need of revision". And in 2000, Eva Kärfve, a sociologist at the University of Lund, published a book which argued that Gillberg's work on DAMP should be rejected.
Perhaps the strongest criticism of DAMP is that Gillberg and his co-workers in Gothenburg are almost the only people doing research on DAMP. Indeed, in a review of DAMP published by Gillberg in 2003, it was noted that there were only "about 50" research papers that had been published on DAMP and that the "vast majority of these have either originated in the author's own clinical and research setting or have been supervised and/or co-authored by him" [Gillberg, 2003, p. 904]. This is in contrast to ADHD, on which "several thousand papers" had been published [Gillberg, 2003, p. 905]. As far as clinical practice goes, DAMP has been primarily accepted only in Gillberg's native Sweden and in Denmark [Gillberg, 2003, p. 904], and even in those countries, acceptance is mixed.
In 2003, Gillberg revised his definition of DAMP. The new definition is as follows:
ADHD as defined in DSM-IV;
developmental coordination disorder (DCD) as defined in DSM-IV;
condition not better accounted for by cerebral palsy; and
IQ should be higher than about 50 [Gillberg, 2003: box 1]. (In the WHO system, this would be a hyperkinetic disorder combined with a developmental disorder of motor function.) About half of children with ADHD are believed to also have DCD [Gillberg, 2003; Martin et al., 2006].
Strong criticism of DAMP, however, has continued. In particular, it has been observed that "the validity and utility of DAMP will remain unclear until stronger evidence of the special status of the overlap between its constituent disorders is provided".
In 2005, there was an hour-long television program broadcast on Swedish TV, questioning why Sweden, almost alone in the world, would accept the DAMP construct. The program featured critical commentary from Sir Michael Rutter. It also considered some of the controversies over Gillberg's Gothenburg Study of Children with DAMP.
The concept of DAMP (deficits in attention, motor control, and perception) has been in clinical use in Scandinavia for about 20 years. DAMP is diagnosed on the basis of concomitant attention deficit/hyperactivity disorder and developmental coordination disorder in children who do not have a severe learning disability or cerebral palsy. In clinically severe form, it affects about 1.5% of the general population of 7-year-old-children; 3-6% are affected by more moderate variants. Boys are overrepresented; girls are currently probably underdiagnosed. There are many comorbid problems/overlapping conditions, including conduct disorder, depression/anxiety, and academic failure. There is a strong link with autism spectrum disorders in severe DAMP. Familial factors and pre- and perinatal risk factors account for much of the variance. Psychosocial risk factors appear to increase the risk of marked psychiatric abnormality in DAMP. The outcome in early adult age was psychosocially poor in one study in almost 60% of unmedicated cases. There are effective interventions available for many of the problems encountered in DAMP.
Notes
References
Andersson, Emelie (2004), Debatten om DAMP: En kontroversstudie (University of Stockholm). [In Swedish]
Bagge, Peter (5 July 2005), "Forskarstrid: DAMP ifrågasätts från fler än ett håll", Sveriges Television. (Summary of televised show, in Swedish.)
Gallup, Raymond; Miller, Clifford G.; Elinder, Leif R.; Brante, Thomas; Kärfve, Eva; Josephson, Staffan (July 2005), "Rapid Responses", British Medical Journal.
Kärfve, Eva (2000), Hjärnspöken: DAMP och hotet mot folkhälsan, Stockholm: Brutus Östlings Bokförlag. [In Swedish.]
Rasmussen N.H. (17 November 2003), "Deficits in attention, motor control, and perception: a brief review", Archives of Disease in Childhood eLetters.
1986 neologisms
1986 quotations
Attention disorders
Motor control
Perception
da:DAMP | Deficits in attention, motor control and perception | Biology | 1,329 |
22,786,112 | https://en.wikipedia.org/wiki/Candy%20%28unit%29 | The candy or candee (Marathi: खंडी, khaṇḍī; Tamil: கண்டி, kaṇṭi; Malayalam: കണ്ഡി, kaṇḍi, കണ്ടി, kaṇṭi), also known as the maunee, was a traditional South Asian unit of mass, equal to 20 maunds and roughly equivalent to 500 pounds avoirdupois (227 kilograms). It was most used in southern India, to the south of Akbar's empire, but has been recorded elsewhere in South Asia. In Marathi, the same word was also used for a unit of area of 120 bighas (25 hectares, very approximately), and it is also recorded as a unit of dry volume.
The candy was generally one of the largest (if not the largest) unit in a given system of measurement. The name is thought to be derived from the Sanskrit खण्डन (root खुड्) khaṇḍ, "to divide, break into pieces", which has also been suggested as the root of the term (sugar-)candy. The word was adopted into several South Asian languages before the compilation of dictionaries, presumably through trade as several Dravidian languages have local synonyms: for example ఖండి kaṇḍi and పుట్టి puṭṭi in Telugu.
Unit of mass
The candy was equal to twenty maunds, but the value of the maund was not standardised across South Asia. There were at least three different approximate values for maund in early nineteenth century India, ranging from 11.34 kg to 37.32 kg, and values from outside India varied even wider. Much of our knowledge of the values of South Asian mass units comes from an 1821 study ordered by the British East India Company and subsequently published as Kelly's Oriental Metrology, although the approximate value of 500 pounds for the candy is attested as early as 1618. The earliest European reference to the candy (1563) puts its mass at 522 arráteis (239.6 kg, 528.2 lbs.).
The three Presidencies of British India had already undertaken a fair degree of standardisation of weights and measures by the time of Kelly's study. In the Madras Presidency, the maund was fixed at 25 lbs. av. (11.340 kg), making the candy equal to 500 lbs. av. (226.796 kg). In the Bombay Presidency, the maund was fixed at 28 lbs. av. (12.701 kg), making the candy exactly equal to 5 hundredweight (560 lbs. av., 254.012 kg). In Bombay itself (present-day Mumbai), a separate value of the candy was recorded for "grain", equal to 8 or 358 lbs. 6 oz. 4 dr. (162.563 kg, see also below). In the Bengal Presidency, where the candy was not traditionally used, the maund (or mun) was a much larger unit, 100 troy pounds (37.324 kg, equivalent to a candy of 746.5 kg).
The effects of this standardisation can also be seen in other territories under direct British control. In Ceylon, the candy (also known as the bahar) was 500 lbs (226.796 kg) as on the Continent. Use of the candy is also recorded in British Burma, where it was the equivalent of 150 viss: its equivalent in Imperial units was measured as 500 lbs. (226.796 kg) in Pegu and 550 lbs. (249.476 kg) in Rangoon.
Perhaps the most striking example is from the princely state of Travancore in southwest India. At the British East India Company trading station of Anjengo, (near modern-day Kadakkavoor), the candy was equal to 35 telong and fixed at 560 lbs. (254.012 kg), as in Bombay. At Colachy (modern-day Kolachal) however, less than 50 miles (80 km) to the south, the candy was measured at only 376 lbs. 1 oz. 2 dr. (170.583 kg).
In the region of the Central Provinces, the maund was roughly 40 lbs., which is probably about the value it had under the Mughal Empire. The candy was not recorded as being in use as a unit of measurement in this region in 1821. Although not a part of the Central Provinces region, the unusually high value recorded for the candy in Baroda, Gujarat (modern-day Vadodara) – 892 lbs. 1 oz. 4 dr. (404.640 kg) – can be explained by this higher value of the Mughal maund. The candy in Surat, the main port of Gujarat, is also consistently quoted as being much larger than the same unit further south.
Unit of area
The candy (खंडी, khaṇḍī) is also recorded as a unit of area in Marathi, equal to 120 bighas. It is impossible to accurately convert this to modern units given the huge variability in the different values of the bigha in different locations. In particular, Kelly's 1821 study of South Asian metrology is completely silent on land measures in the Bombay Presidency. Molesworth defines the Marathi bigha (बिघा, bighā) as equal to twenty pandas (पांड, pāṇḍa) or to 400 square (काठी, kāṭhī), but also notes that it varies in different districts. The same author defines the as "a land measure,—five cubits and five handbreadths […] also the measuring rod": other authors are silent on the unit. A cubit is roughly equal to five handbreadths, so the can be taken to be roughly 25 square cubits: that is, 8100 square inches or 6.25 square yards. This would make the bigha roughly 2500 square yards, or half an acre, in agreement with measurements in other areas of India. The candy, therefore, can be taken to be approximately 60 acres or 25 hectares.
The celebrated Scottish orientalist Sir Henry Yule gives a slightly larger value for the candy as a unit of area ("approximately 75 acres"), and describes it as the area of land which will produce one candy of grain. The Telugu unit of the putty (పుట్టి, puṭṭi) is also used in the same way: one putty of land is that area which will produce one putty of rice.
Unit of dry volume
Several sources also describe the candy as a unit of dry measure. Again, it is difficult to give an accurate conversion to modern units, as most sources quote conversions to mass units for specific goods, and the few specific conversion factors that exist range from 8 to 25 bushels. More plausible is that one candy of dry measure was the volume that would have been occupied by one candy (in mass) of water, that is about 254 litres (7 bushels) in Bombay (present-day Mumbai).
One candy of "grain" (unspecified) in Bombay was recorded by Kelly as 8 or 358 lbs. 6 oz. 4 dr. (162.563 kg), compared to a standard Bombay candy of 560 lbs. (254.012 kg), a factor of 0.640. This factor is lower than the relative density of modern hulled rice (0.753) but higher than that of rough rice (0.577).
One for salt measure for Bombay was reported as 1607.6 cubic inches (26.344 litres), implying a candy for dry measure of salt as 210.8 litres: the factor (1.20, based on 254 litres for one candy of water) is identical to the relative density of caked salt.
The Ceylonese standard was a cube of sides 11.57 inches, that is 25.41 litres.
Molesworth defines the Marathi (पल्ला, ) as 120 seers, implying a candy of 960 seers and a maund of 48 seers. The Bombay seer is given by Kelly as 11 oz. 3 dr. (317.2 g) for both grain and other commercial goods.
Not all grain measures in candies should be taken as dry measures. The United Nations Statistical Office reported that the candy was in use in the 20th century:
in east India for measuring rice, with a value of approximately 210.636 kg compared to the old Madras standard candy of 226.796 kg;
in Ceylon (later Sri Lanka) for measuring copra, with a value of 560 lbs.
Both of these are obviously related to the candy as a unit of mass.
Notes
References
External links
"candy" at sizes.com
Units of mass
Customary units in India
Obsolete units of measurement | Candy (unit) | Physics,Mathematics | 1,773 |
30,433,313 | https://en.wikipedia.org/wiki/Astronomical%20Society%20of%20South%20Australia | The Astronomical Society of South Australia (ASSA) was founded in 1892 and is the oldest society of its kind in Australia. It is the only representative body for amateur astronomy in the state of South Australia.
It holds regular general monthly meetings, frequent meetings for members of specialised groups and has available two observatories, one with a 300mm telescope at The Heights School within easy reach of Adelaide and used primarily for public viewing, and a second at Stockport with 500mm and 450mm telescopes presently in service and a larger 36-inch instrument currently being considered.
Membership
The ASSA has approximately 500 members. People of all ages are able to join.
Observatories and facilities
The ASSA has a choice of facilities available to members and guests:
Stockport Observatory - this was badly damaged in a severe storm in 2010, but in late 2013 the Astronomical Society of South Australia was given $50,000 by the State Government to pay for half of the cost of a new dome. The observatory is used as a teaching tool, hosting groups of curious students and members the public, but it also has an impressive research record.
The Heights Observatory
Tooperang Observing Site
Whyalla Middleback Observing Site
Adelaide Planetarium
The ASSA Library
The VicSouth Desert Spring Star Party is an annual weekend of astronomy, jointly hosted by the Astronomical Society of Victoria and the Astronomical Society of South Australia. It is held around October–November near the town of Nhill in western Victoria, Australia.
Notable Members
Professor Sir Robert Chapman CMG, BA, M.I.C.E., MIEAust (1866–1942) was president for 32 years.
William A. (Bill) Bradfield AM (1927-2014) - with 18 comets and 1 asteroid bearing his name. He was a rocket propulsion and ballistics expert (retired). There is a Bradfield Award given by the Astronomical Society of South Australia to an amateur who displays exceeding accomplishment in a given year in the field of astronomy, given in honour of Bill's achievements. Bill was a long-time ASSA Life Member, past-President (1977–79) and was inducted into the ASSA Hall of Fame in 2013.
See also
List of telescopes of Australia
List of astronomical societies
References
External links
Astronomy in Australia
Scientific organizations established in 1892
Amateur astronomy organizations
Scientific organisations based in Australia
Clubs and societies in South Australia | Astronomical Society of South Australia | Astronomy | 477 |
55,169,547 | https://en.wikipedia.org/wiki/%CE%93-Octalactone | γ-Octalactone is a lactone and aroma compound with the chemical formula C8H14O2. It has a coconut flavor. It is also a frequent component of urban aerosols as well as some liquors.
References
Gamma-lactones | Γ-Octalactone | Chemistry | 55 |
41,973,145 | https://en.wikipedia.org/wiki/Critical%20anthropomorphism | Critical anthropomorphism is an approach in the study of animal behavior that integrates scientific knowledge about a species, including its perceptual world, ecological context, and evolutionary history, to generate hypotheses through the lens of human intuition and understanding. This method contrasts with classical anthropomorphism, which often uncritically attributes human traits and emotions to animals.
The term was introduced by Gordon Burghardt in the mid-1980s. Burghardt emphasized the importance of using feelings, perceptions, evolutionary knowledge, and careful behavioral descriptions to provide relevant insights into animal behavior. This approach is seen as a practical application of ethology, the scientific study of animal behavior.
Historically, the concept draws on the ideas of Jakob von Uexküll, who introduced the notions of umwelt (the perceptual world of an organism) and innenwelt (the inner world of an organism). These ideas highlight that different species perceive the world uniquely based on their sensory capacities. Early ethologists like Nikolaas Tinbergen, Konrad Lorenz, and Karl von Frisch also considered the role of subjectivity in animal behavior research.
Critical anthropomorphism calls for an account of animal consciousness and cognition that acknowledges sentient creatures as having lived bodily experiences. This perspective allows researchers to generate objectively testable ideas about animal behavior by leveraging human intuition and knowledge of an animal’s natural history.
Historical Roots of Critical Anthropomorphism
The concept of critical anthropomorphism has its roots in the ideas of Jakob von Uexküll, who introduced the notions of umwelt (the perceptual world of an organism) and innenwelt (the inner world of an organism). These ideas emphasize that different species perceive the world uniquely based on their sensory capacities. This perspective laid the groundwork for understanding animal behavior through their own perceptual experiences rather than solely through human observation.
Early ethologists like Nikolaas Tinbergen, Konrad Lorenz, and Karl von Frisch also contributed to the foundation of critical anthropomorphism by considering the role of subjectivity in animal behavior research. They recognized that understanding animal behavior required acknowledging the animals’ perspectives and experiences.
Charles Darwin is another significant figure in the historical development of critical anthropomorphism. In his work, “The Expression of the Emotions in Man and Animals,” Darwin used everyday language to describe animal mentality, employing a form of critical anthropomorphism by ascribing mental states based on shared recognition and empirical knowledge. This approach highlighted the continuity between human and animal emotions and behaviors, challenging the strict separation between humans and other animals.
The term “critical anthropomorphism” itself was introduced by Gordon Burghardt in the mid-1980s. Burghardt emphasized the importance of using feelings, perceptions, evolutionary knowledge, and careful behavioral descriptions to provide relevant insights into animal behavior. This approach is seen as a practical application of ethology, the scientific study of animal behavior.
Overall, the historical roots of critical anthropomorphism are deeply intertwined with the development of ethology and the recognition of the importance of considering animals’ subjective experiences in understanding their behavior.
Implementation and Examples of Critical Anthropomorphism
Implementation
Critical anthropomorphism is an approach that combines scientific knowledge, natural history, and human intuition. Researchers use this approach to generate hypotheses about animal behavior. They carefully observe animals and consider their perceptual worlds, ecological contexts, and evolutionary histories. Researchers use their own feelings and perceptions, informed by scientific data, to make educated guesses about what animals might be experiencing or why they behave in certain ways.
Examples
Foraging Tactics in Snakes: Researchers studying snake behavior might use critical anthropomorphism to hypothesize how a snake perceives its environment while hunting. By considering the snake’s sensory capabilities and natural history, scientists can make informed guesses about how the snake detects prey and decides when to strike.
Courtship Behavior in Fruit Flies: In studying the courtship behavior of fruit flies, researchers might use critical anthropomorphism to understand the motivations behind certain actions. By considering the evolutionary pressures and sensory experiences of fruit flies, scientists can hypothesize why certain courtship behaviors have evolved and how they are perceived by the flies.
Conservation Planning for Wildlife Management: Critical anthropomorphism can be applied in conservation efforts to better understand the needs and behaviors of endangered species. For example, when planning a wildlife reserve, conservationists might use critical anthropomorphism to predict how animals will interact with their environment and each other, ensuring that the reserve meets their ecological and social needs.
Zoo Exhibit Design: Zoos can use critical anthropomorphism to design exhibits that cater to the perceptual and behavioral needs of animals. By considering how animals perceive their surroundings and what stimulates their natural behaviors, zoos can create environments that promote the well-being of the animals and provide educational experiences for visitors.
These examples illustrate how critical anthropomorphism can be a valuable tool in understanding and predicting animal behavior, leading to more effective research, conservation, and animal care practices.
Ethical Considerations of Critical Anthropomorphism
Critical anthropomorphism involves using human intuition and scientific knowledge to understand animal behavior, but it also raises important ethical considerations. Some key consdierations are:
Avoiding Misrepresentation:
One of the primary ethical concerns is the potential for misrepresenting animals. Anthropomorphism can lead to projecting human emotions and motivations onto animals inaccurately. However, avoiding anthropomorphism entirely can result in mechanomorphism, where animals are viewed as mere machines.
Critical anthropomorphism aims to strike a balance by using informed projections that are scientifically grounded and contextually appropriate.
Enhancing Empathy and Understanding:
When used carefully, critical anthropomorphism can enhance empathy towards animals. By considering animals’ perspectives and experiences, researchers and the public can develop a deeper understanding and appreciation of animal welfare.
This approach can also improve the ethical treatment of animals in various settings, including research, zoos, and conservation efforts.
Communicative Strategy:
Anthropomorphism is an effective communicative strategy in animal ethics. It helps bridge the gap between human and animal experiences, making it easier to convey the importance of animal welfare to a broader audience.
By using relatable human terms and emotions, critical anthropomorphism can make scientific findings more accessible and compelling.
Ethical Research Practices:
In research settings, critical anthropomorphism encourages scientists to consider the subjective experiences of animals. This can lead to more humane and ethical research practices, ensuring that animals are not merely treated as objects but as sentient beings with their own needs and experiences.
It also promotes the development of research methodologies that minimize harm and stress to animals.
Legal and Policy Implications:
The ethical considerations of critical anthropomorphism extend to legal and policy frameworks. Recognizing animals as sentient beings with subjective experiences can influence laws and regulations related to animal welfare and rights.
This perspective can drive changes in how animals are treated in industries such as agriculture, entertainment, and research.
Overall, critical anthropomorphism, when applied thoughtfully, can lead to more ethical and empathetic interactions with animals. It encourages a nuanced understanding of animal behavior and promotes practices that respect and protect animal welfare.
Contemporary Views on Critical Anthropomorphism
In recent years, critical anthropomorphism has gained traction as a valuable approach in the study of animal behavior and cognition. Some contemporary perspectives are listed as:
Integration with Evolutionary Theory:
Contemporary researchers emphasize the importance of integrating critical anthropomorphism with evolutionary theory. This approach acknowledges that there is no clear evolutionary gap between humans and other animals, which supports the idea that animals can have complex mental states and experiences.
By considering evolutionary continuity, scientists can make more informed and accurate attributions of mental phenomena and emotions to animals.
Balancing Objectivity and Subjectivity:
Modern ethologists and cognitive scientists recognize the need to balance objectivity with subjectivity. While traditional behaviorism focused solely on observable phenomena, critical anthropomorphism allows for the consideration of animals’ subjective experiences without falling into the trap of naive anthropomorphism.
This balanced approach helps researchers generate hypotheses that are both scientifically rigorous and empathetic towards animals.
Ethical and Practical Applications:
Critical anthropomorphism is increasingly seen as an ethical and practical tool in various fields, including animal welfare, conservation, and zoo management. By understanding animals’ perspectives, professionals can design better environments and interventions that cater to the animals’ needs.
This approach also promotes more humane treatment of animals in research and other settings, as it encourages scientists to consider the animals’ well-being and subjective experiences.
Challenges and Criticisms:
Despite its growing acceptance, critical anthropomorphism faces challenges and criticisms. Some scholars argue that it still risks anthropocentrism and may lead to over-interpretation of animal behavior.
Others believe that while it is a useful heuristic, it should be applied cautiously and always backed by empirical evidence to avoid misrepresentation.
Future Directions:
The future of critical anthropomorphism lies in its continued refinement and integration with other scientific approaches. Researchers are exploring ways to combine it with advanced technologies, such as neuroimaging and machine learning, to gain deeper insights into animal cognition and behavior.
There is also a growing interest in interdisciplinary collaborations, bringing together ethologists, psychologists, philosophers, and other experts to develop a more comprehensive understanding of animal minds.
Overall, contemporary views on critical anthropomorphism highlight its potential to enhance the understanding of animals while promoting ethical and empathetic research practices.
Key Figures and Works in Critical Anthropomorphism
1. Gordon Burghardt
Introduction of the Term: Gordon Burghardt is credited with introducing the term “critical anthropomorphism” in the mid-1980s. His work emphasized the importance of using human intuition and scientific knowledge to generate hypotheses about animal behavior.
Significant Contributions: Burghardt’s research has focused on the integration of evolutionary theory, natural history, and behavioral observations to understand animal cognition and behavior. His writings have been influential in promoting a balanced approach to studying animals.
2. Jakob von Uexküll
Concepts of Umwelt and Innenwelt: Jakob von Uexküll’s ideas of umwelt (the perceptual world of an organism) and innenwelt (the inner world of an organism) have been foundational in the development of critical anthropomorphism. These concepts highlight the unique ways in which different species perceive and interact with their environments.
Influence on Ethology: Uexküll’s work has influenced many ethologists and researchers in understanding the subjective experiences of animals, which is a core aspect of critical anthropomorphism.
3. Charles Darwin
The Expression of the Emotions in Man and Animals: In his seminal work, Darwin used everyday language to describe animal emotions and behaviors, employing a form of critical anthropomorphism. He argued for the continuity between human and animal emotions, challenging the strict separation between humans and other animals.
Legacy: Darwin’s approach laid the groundwork for future researchers to consider the mental states and subjective experiences of animals in a scientifically rigorous manner.
4. Edward Chace Tolman
Cognitive Maps: Tolman’s work on cognitive maps in rats is an early example of critical anthropomorphism. He proposed that animals have mental representations of their environments, which they use to navigate and make decisions.
Impact on Animal Cognition Studies: Tolman’s research has been influential in the field of animal cognition, demonstrating that animals can have complex mental processes similar to humans.
5. Contemporary Researchers
Interdisciplinary Approaches: Modern researchers continue to build on the foundations laid by these key figures. They integrate insights from ethology, psychology, philosophy, and other disciplines to develop a more comprehensive understanding of animal minds.
Technological Advancements: Advances in technology, such as neuroimaging and machine learning, are being used to explore animal cognition in greater detail, furthering the principles of critical anthropomorphism.
These key figures and their works have significantly shaped the field of critical anthropomorphism, providing valuable insights into the subjective experiences and cognitive abilities of animals.
Practical Applications of Critical Anthropomorphism
1. Animal Behavior Research
Hypothesis Generation: Critical anthropomorphism is used to generate hypotheses about animal behavior by considering animals’ perceptual worlds and evolutionary histories. This approach helps researchers design experiments that are more likely to yield meaningful insights into animal cognition and behavior.
Behavioral Enrichment: In laboratory settings, understanding animals’ subjective experiences can lead to better enrichment practices, improving the welfare of animals used in research.
2. Conservation Efforts
Wildlife Management: Conservationists use critical anthropomorphism to predict how animals will interact with their environments and each other. This helps in designing effective wildlife reserves and conservation strategies that cater to the ecological and social needs of animals.
Human-Wildlife Conflict Mitigation: By understanding animals’ perspectives, conservationists can develop strategies to reduce conflicts between humans and wildlife, such as creating corridors for safe animal movement or implementing non-lethal deterrents.
3. Zoo and Aquarium Exhibit Design
Naturalistic Environments: Zoos and aquariums use critical anthropomorphism to design exhibits that mimic natural habitats and stimulate natural behaviors. This approach enhances the well-being of captive animals and provides educational experiences for visitors.
Interactive Displays: Exhibits designed with an understanding of animals’ sensory experiences can include interactive elements that engage both the animals and the public, fostering a deeper connection and understanding.
4. Animal Welfare and Ethics
Improved Welfare Standards: Critical anthropomorphism informs the development of welfare standards that consider the subjective experiences of animals. This leads to more humane treatment in various settings, including farms, laboratories, and shelters.
Ethical Decision-Making: By acknowledging animals’ sentience and subjective experiences, policymakers and ethicists can make more informed decisions regarding animal rights and welfare.
5. Education and Public Awareness
Educational Programs: Critical anthropomorphism is used in educational programs to teach the public about animal behavior and welfare. By presenting animals’ experiences in relatable terms, educators can foster empathy and promote conservation efforts.
Media and Communication: Documentaries, books, and other media that use critical anthropomorphism can effectively communicate the complexities of animal behavior and the importance of conservation, reaching a wide audience.
These practical applications demonstrate how critical anthropomorphism can enhance our understanding of animals and improve their treatment across various domains.
See also
Animal consciousness
References
Sources
Further reading
Animal cognition
Animal emotions
Anthropomorphism
Consciousness
Ethology
Point of view | Critical anthropomorphism | Biology | 3,113 |
2,473,213 | https://en.wikipedia.org/wiki/Skype%20for%20Business | Skype for Business (formerly Microsoft Lync and Office Communicator) is an enterprise software application for instant messaging and videotelephony developed by Microsoft as part of the Microsoft 365 (formerly Office) suite. It is designed for use with the on-premises Skype for Business Server software, and a software as a service version offered as part of 365. It supports text, audio, and video chat, and integrates with Microsoft 365 components such as Exchange and SharePoint.
The software was previously named Lync before rebranding to Skype for Business in 2015, co-branding it with the Microsoft-owned consumer messaging platform Skype (which had begun to integrate with Lync in 2013). Despite the same branding, Skype for Business and Skype have almost nothing in common and function as separate platforms.
In September 2017, Microsoft announced that it would phase out Skype for Business Online in favor of Microsoft Teams, a new cloud-based collaboration platform. Support for Skype for Businesses Online ended in July 2021, although a new version of Skype for Business Server will be available with a subscription license.
History
Microsoft released Office Communicator 2007 to production on July 28, 2007, and launched it on October 27, 2007. It was followed by Office Communicator 2007 R2, released on March 19, 2009. Microsoft released the successor to Office Communicator, Lync 2010, on January 25, 2011. In November 2010, the platform was renamed Lync.
In May 2013, Microsoft announced that it would allow Lync users to communicate with Skype, a consumer IM platform it had acquired in 2011. This initially included support for text and voice communications. On November 11, 2014, Microsoft announced that Lync would be renamed Skype for Business in 2015, also adding support for video calls with Skype users.
On September 22, 2015, Skype for Business 2016 was released alongside Office 2016. On October 27, 2016, the Skype for Business for Mac client was released.
On September 25, 2017, Microsoft announced that Skype for Business Online would be discontinued in the future in favor of Microsoft Teams, a cloud-based collaboration platform for corporate groups (comparable to Slack) integrating persistent messaging, video conferencing, file storage, and application integration. Microsoft released a final on-premises version of Skype for Business Server as part of Office 2019 in late 2018, and announced in July 2019 that the hosted Skype for Business Online will cease functioning on July 31, 2021. Since September 2019, Skype for Business Online is no longer offered to new Microsoft 365 subscribers, and are being directed to Microsoft Teams instead. The next version of Skype for Business Server will be available with a subscription license.
Versions
Exchange 2000 Conferencing
Windows Messenger 5.0 (Live Communications Server 2003)
Windows Messenger 5.1 and Microsoft Office Communicator 2005 (Live Communications Server 2005)
Office Communicator 2007
Office Communicator 2007 R2
Lync 2010
Lync 2013
Skype for Businesses 2015
Skype for Businesses 2016
Skype for Businesses 2019
Skype for Business for Microsoft 365
Features
The Basic features of Skype for Business include:
Instant messaging (IM)
Audio calls
Video calls
Desktop sharing
Advanced features relate to integration with other Microsoft software:
Availability of contacts based on Microsoft Outlook contacts stored in a Microsoft Exchange Server
Users can retrieve contact lists from a local directory service such as Microsoft Exchange Server
Microsoft Office can show if other people are working on the same document
All communication between the clients takes place through a Skype for Business Server. This makes communications more secure, as messages do not need to leave the corporate intranet, unlike with the Internet-based Windows Live Messenger. The server can be set to relay messages to other instant messaging networks, avoiding installation of extra software at the client side.
A number of client types are available for Microsoft Skype for Business, including mobile clients.
Uses SIP as the basis for its client communication protocol
Offers support for TLS and SRTP to encrypt and secure signaling and media traffic
Allows sharing files
Note: With the release of Lync Server 2013 in October 2012, a new collaboration feature "Persistent Group Chat" which allows multi-party chat with preservation of content between chat sessions was introduced. However, only the native Windows OS client and no other platform supports this feature at this time. The main new features of this version are the addition of real-time multi-client collaborative software capabilities, (which allow teams of people to see and simultaneously work on the same documents and communications session). Lync and Skype for Business implement these features as follows:
Collaboration through Whiteboard documents, where the participants have freedom to share text, drawing and graphical annotations.
Collaboration through PowerPoint documents, where the participants can control and see presentations, as well as allow everybody to add text, drawing and graphical annotations.
Polling lists, where Presenters can organize polls and all participants can vote and see results.
Desktop sharing, usually by allowing participants to see and collaborate on a Windows screen
Windows applications sharing, by allowing participants to see and collaborate on a specific application.
All collaboration sessions get automatically defined as conferences, where clients can invite more contacts.
Conference initiators (usually called "organizers") can either promote participants to act as presenters or demote them to act as attendees. They can also define some basic policies about what presenters and attendees can see and do. Deeper details of policy permissions are defined at server level.
Following Microsoft's acquisition of Skype in May 2011, the Lync and Skype platforms could be connected, but sometimes only after lengthy provisioning time.
Extensions
Skype for Business uses a number of extensions to the SIP/SIMPLE instant-messaging protocol for some features. As with most instant-messaging platforms, non-Microsoft instant-messaging clients that have not implemented these publicly available extensions may not work correctly or have complete functionality. Skype for Business supports federated presence and IM to other popular instant message services such as AOL, Yahoo, MSN, and any service using the XMPP protocol, although support for XMPP has been deprecated in Skype for Business 2019. Text instant-messaging in a web browser is available via Skype for Business integration within Exchange Outlook Web App.
Although other IM protocols such as AIM and Yahoo! do have wider support by third-party clients, these protocols have been largely reverse-engineered by outside developers. Microsoft does offer details of its extensions on MSDN and provides an API kit to help developers build platforms that can interoperate with Skype for Business Server and clients.
Clients
As of May 2018, the following Skype for Business clients are available:
Windows (Pro and Enterprise only, can download free Skype for Business Basic client) and macOS (included with Microsoft 365)
Linux (provided by TEL.RED)
iOS (Microsoft app in iTunes app store; alternative client provided by TEL.RED)
Android (Microsoft app in Google Play; alternative client provided by TEL.RED)
Windows Phone and Windows 10 Mobile apps were discontinued by Microsoft in May 2018.
See also
Similar discontinued Microsoft products
Windows Meeting Space
Microsoft NetMeeting
Microsoft Office Live Meeting
Others
Comparison of web conferencing software
List of Microsoft–Nortel Innovative Communications Alliance products
References
External links
Download Skype for Business Apps Across All Your Devices
Download Microsoft Skype for Business Basic from Official Microsoft Download Center
Install Skype for Business – Office Support
Skype for Business Online to Be Retired in 2021
Skype
Innovative Communications Alliance products
Microsoft Office
Windows instant messaging clients
Videotelephony
IOS software
Android (operating system) software
Business chat software
2015 software | Skype for Business | Technology | 1,564 |
233,271 | https://en.wikipedia.org/wiki/Brown%20algae | Brown algae (: alga) are a large group of multicellular algae comprising the class Phaeophyceae. They include many seaweeds located in colder waters of the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and polar regions. Many brown algae, such as members of the order Fucales, commonly grow along rocky seashores. Most brown algae live in marine environments, where they play an important role both as food and as a potential habitat. For instance, Macrocystis, a kelp of the order Laminariales, may reach in length and forms prominent underwater kelp forests that contain a high level of biodiversity. Another example is Sargassum, which creates unique floating mats of seaweed in the tropical waters of the Sargasso Sea that serve as the habitats for many species. Some members of the class, such as kelps, are used by humans as food.
Between 1,500 and 2,000 species of brown algae are known worldwide. Some species, such as Ascophyllum nodosum, have become subjects of extensive research in their own right due to their commercial importance. They also have environmental significance through carbon fixation.
Brown algae belong to the Stramenopiles, a clade of eukaryotic organisms that are distinguished from green plants by having chloroplasts surrounded by four membranes, suggesting that they were acquired secondarily from a symbiotic relationship between a basal eukaryote and a red or green alga. Most brown algae contain the pigment fucoxanthin, which is responsible for the distinctive greenish-brown color that gives them their name. Brown algae are unique among Stramenopiles in developing into multicellular forms with differentiated tissues, but they reproduce by means of flagellated spores and gametes that closely resemble cells of single-celled Stramenopiles. Genetic studies show their closest relatives to be the yellow-green algae.
Morphology
Brown algae exist in a wide range of sizes and forms. The smallest members of the group grow as tiny, feathery tufts of threadlike cells no more than a few centimeters (a few inches) long. Some species have a stage in their life cycle that consists of only a few cells, making the entire alga microscopic. Other groups of brown algae grow to much larger sizes. The rockweeds and leathery kelps are often the most conspicuous algae in their habitats. Kelps can range in size from the sea palm Postelsia to the giant kelp Macrocystis pyrifera, which grows to over long and is the largest of all the algae. In form, the brown algae range from small crusts or cushions to leafy free-floating mats formed by species of Sargassum. They may consist of delicate felt-like strands of cells, as in Ectocarpus, or of flattened branches resembling a fan, as in Padina.
Regardless of size or form, two visible features set the Phaeophyceae apart from all other algae. First, members of the group possess a characteristic color that ranges from an olive green to various shades of brown. The particular shade depends upon the amount of fucoxanthin present in the alga. Second, all brown algae are multicellular. There are no known species that exist as single cells or as colonies of cells, and the brown algae are the only major group of seaweeds that does not include such forms. However, this may be the result of classification rather than a consequence of evolution, as all the groups hypothesized to be the closest relatives of the browns include single-celled or colonial forms. They can change color depending on salinity, ranging from reddish to brown.
Visible structures
Whatever their form, the body of all brown algae is termed a thallus, indicating that it lacks the complex xylem and phloem of vascular plants. This does not mean that brown algae completely lack specialized structures. But, because some botanists define "true" stems, leaves, and roots by the presence of these tissues, their absence in the brown algae means that the stem-like and leaf-like structures found in some groups of brown algae must be described using different terminology. Although not all brown algae are structurally complex, those that are typically possess one or more characteristic parts.
A holdfast is a rootlike structure present at the base of the alga. Like a root system in plants, a holdfast serves to anchor the alga in place on the substrate where it grows, and thus prevents the alga from being carried away by the current. Unlike a root system, the holdfast generally does not serve as the primary organ for water uptake, nor does it take in nutrients from the substrate. The overall physical appearance of the holdfast differs among various brown algae and among various substrates. It may be heavily branched, or it may be cup-like in appearance. A single alga typically has just one holdfast, although some species have more than one stipe growing from their holdfast.
A stipe is a stalk or stemlike structure present in an alga. It may grow as a short structure near the base of the alga (as in Laminaria), or it may develop into a large, complex structure running throughout the algal body (as in Sargassum or Macrocystis). In the most structurally differentiated brown algae (such as Fucus), the tissues within the stipe are divided into three distinct layers or regions. These regions include a central pith, a surrounding cortex, and an outer epidermis, each of which has an analog in the stem of a vascular plant. In some brown algae, the pith region includes a core of elongated cells that resemble the phloem of vascular plants both in structure and function. In others (such as Nereocystis), the center of the stipe is hollow and filled with gas that serves to keep that part of the alga buoyant. The stipe may be relatively flexible and elastic in species like Macrocystis pyrifera that grow in strong currents, or may be more rigid in species like Postelsia palmaeformis that are exposed to the atmosphere at low tide.
Many algae have a flattened portion that may resemble a leaf, and this is termed a blade, lamina, or frond. The name blade is most often applied to a single undivided structure, while frond may be applied to all or most of an algal body that is flattened, but this distinction is not universally applied. The name lamina refers to that portion of a structurally differentiated alga that is flattened. It may be a single or a divided structure, and may be spread over a substantial portion of the alga. In rockweeds, for example, the lamina is a broad wing of tissue that runs continuously along both sides of a branched midrib. The midrib and lamina together constitute almost all of a rockweed, so that the lamina is spread throughout the alga rather than existing as a localized portion of it.
In some brown algae, there is a single lamina or blade, while in others there may be many separate blades. Even in those species that initially produce a single blade, the structure may tear with rough currents or as part of maturation to form additional blades. These blades may be attached directly to the stipe, to a holdfast with no stipe present, or there may be an air bladder between the stipe and blade. The surface of the lamina or blade may be smooth or wrinkled; its tissues may be thin and flexible or thick and leathery. In species like Egregia menziesii, this characteristic may change depending upon the turbulence of the waters in which it grows. In other species, the surface of the blade is coated with slime to discourage the attachment of epiphytes or to deter herbivores. Blades are also often the parts of the alga that bear the reproductive structures.
Gas-filled floats called pneumatocysts provide buoyancy in many kelps and members of the Fucales. These bladder-like structures occur in or near the lamina, so that it is held nearer the water surface and thus receives more light for photosynthesis. Pneumatocysts are most often spherical or ellipsoidal, but can vary in shape among different species. Species such as Nereocystis luetkeana and Pelagophycus porra bear a single large pneumatocyst between the top of the stipe and the base of the blades. In contrast, the giant kelp Macrocystis pyrifera bears many blades along its stipe, with a pneumatocyst at the base of each blade where it attaches to the main stipe. Species of Sargassum also bear many blades and pneumatocysts, but both kinds of structures are attached separately to the stipe by short stalks. In species of Fucus, the pneumatocysts develop within the lamina itself, either as discrete spherical bladders or as elongated gas-filled regions that take the outline of the lamina in which they develop.
Growth
The brown algae include the largest and fastest growing of seaweeds. Fronds of Macrocystis may grow as much as per day, and the stipes can grow in a single day.
Growth in most brown algae occurs at the tips of structures as a result of divisions in a single apical cell or in a row of such cells. They are single cellular organisms. As this apical cell divides, the new cells that it produces develop into all the tissues of the alga. Branchings and other lateral structures appear when the apical cell divides to produce two new apical cells. However, a few groups (such as Ectocarpus) grow by a diffuse, unlocalized production of new cells that can occur anywhere on the thallus.
Tissue organization
The simplest brown algae are filamentous—that is, their cells are elongate and have septa cutting across their width. They branch by getting wider at their tip, and then dividing the widening.
These filaments may be haplostichous or polystichous, multiaxial or monoaxial forming or not a pseudoparenchyma. Besides fronds, there are the large in size parenchymatic kelps with three-dimensional development and growth and different tissues (meristoderm, cortex and medulla) which could be consider the trees of the sea. There are also the Fucales and Dictyotales smaller than kelps but still parenchymatic with the same kind of distinct tissues.
The cell wall consists of two layers; the inner layer bears the strength, and consists of cellulose; the outer wall layer is mainly algin, and is gummy when wet but becomes hard and brittle when it dries out. Specifically, the brown algal cell wall consists of several components with alginates and sulphated fucan being its main ingredients, up to 40% each of them. Cellulose, a major component from most plant cell walls, is present in a very small percentage, up to 8%. Cellulose and alginate biosynthesis pathways seem to have been acquired from other organisms through endosymbiotic and horizontal gene transfer respectively, while the sulphated polysaccharides are of ancestral origin. Specifically, the cellulose synthases seem to come from the red alga endosymbiont of the photosynthetic stramenopiles ancestor, and the ancestor of brown algae acquired the key enzymes for alginates biosynthesis from an actinobacterium. The presence and fine control of alginate structure in combination with the cellulose which existed before it, gave potentially the brown algae the ability to develop complex structurally multicellular organisms like the kelps.
Evolutionary history
Genetic and ultrastructural evidence place the Phaeophyceae among the heterokonts (Stramenopiles), a large assemblage of organisms that includes both photosynthetic members with plastids (such as the diatoms) as well as non-photosynthetic groups (such as the slime nets and water molds). Although some heterokont relatives of the brown algae lack plastids in their cells, scientists believe this is a result of evolutionary loss of that organelle in those groups rather than independent acquisition by the several photosynthetic members. Thus, all heterokonts are believed to descend from a single heterotrophic ancestor that became photosynthetic when it acquired plastids through endosymbiosis of another unicellular eukaryote.
The closest relatives of the brown algae include unicellular and filamentous species, but no unicellular species of brown algae are known. However, most scientists assume that the Phaeophyceae evolved from unicellular ancestors. DNA sequence comparison also suggests that the brown algae evolved from the filamentous Phaeothamniophyceae, Xanthophyceae, or the Chrysophyceae between 150 and 200 million years ago. In many ways, the evolution of the brown algae parallels that of the green algae and red algae, as all three groups possess complex multicellular species with an alternation of generations. Analysis of 5S rRNA sequences reveals much smaller evolutionary distances among genera of the brown algae than among genera of red or green algae, which suggests that the brown algae have diversified much more recently than the other two groups.
Fossils
The occurrence of Phaeophyceae as fossils is rare due to their generally soft-bodied nature, and scientists continue to debate the identification of some finds. Part of the problem with identification lies in the convergent evolution of morphologies between many brown and red algae. Most fossils of soft-tissue algae preserve only a flattened outline, without the microscopic features that permit the major groups of multicellular algae to be reliably distinguished. Among the brown algae, only species of the genus Padina deposit significant quantities of minerals in or around their cell walls. Other algal groups, such as the red algae and green algae, have a number of calcareous members. Because of this, they are more likely to leave evidence in the fossil record than the soft bodies of most brown algae and more often can be precisely classified.
Fossils comparable in morphology to brown algae are known from strata as old as the Upper Ordovician, but the taxonomic affinity of these impression fossils is far from certain. Claims that earlier Ediacaran fossils are brown algae have since been dismissed. While many carbonaceous fossils have been described from the Precambrian, they are typically preserved as flattened outlines or fragments measuring only millimeters long. Because these fossils lack features diagnostic for identification at even the highest level, they are assigned to fossil form taxa according to their shape and other gross morphological features. A number of Devonian fossils termed fucoids, from their resemblance in outline to species in the genus Fucus, have proven to be inorganic rather than true fossils. The Devonian megafossil Prototaxites, which consists of masses of filaments grouped into trunk-like axes, has been considered a possible brown alga. However, modern research favors reinterpretation of this fossil as a terrestrial fungus or fungal-like organism. Likewise, the fossil Protosalvinia was once considered a possible brown alga, but is now thought to be an early land plant.
A number of Paleozoic fossils have been tentatively classified with the brown algae, although most have also been compared to known red algae species. Phascolophyllaphycus possesses numerous elongate, inflated blades attached to a stipe. It is the most abundant of algal fossils found in a collection made from Carboniferous strata in Illinois. Each hollow blade bears up to eight pneumatocysts at its base, and the stipes appear to have been hollow and inflated as well. This combination of characteristics is similar to certain modern genera in the order Laminariales (kelps). Several fossils of Drydenia and a single specimen of Hungerfordia from the Upper Devonian of New York have also been compared to both brown and red algae. Fossils of Drydenia consist of an elliptical blade attached to a branching filamentous holdfast, not unlike some species of Laminaria, Porphyra, or Gigartina. The single known specimen of Hungerfordia branches dichotomously into lobes and resembles genera like Chondrus and Fucus or Dictyota.
The earliest known fossils that can be assigned reliably to the Phaeophyceae come from Miocene diatomite deposits of the Monterey Formation in California. Several soft-bodied brown macroalgae, such as Julescraneia, have been found.
Classification
Phylogeny
Based on the work of Silberfeld, Rousseau & de Reviers 2014.
Taxonomy
This is a list of the orders in the class Phaeophyceae:
Class Phaeophyceae Hansgirg 1886 [Fucophyceae; Melanophycidae Rabenhorst 1863 stat. nov. Cavalier-Smith 2006]
Subclass Discosporangiophycidae Silberfeld, Rousseau & Reviers 2014
Order Discosporangiales Schmidt 1937 emend. Kawai et al. 2007
Family Choristocarpaceae Kjellman 1891
Family Discosporangiaceae Schmidt 1937
Subclass Ishigeophycidae Silberfeld, Rousseau & Reviers 2014
Order Ishigeales Cho & Boo 2004
Family Ishigeaceae Okamura 1935
Family Petrodermataceae Silberfeld, Rousseau & Reviers 2014
Subclass Dictyotophycidae Silberfeld, Rousseau & Reviers 2014
Order Dictyotales Bory de Saint-Vincent 1828 ex Phillips et al.
Family Dictyotaceae Lamouroux ex Dumortier 1822 [Scoresbyellaceae Womersley 1987; Dictyopsidaceae]
Order Onslowiales Draisma & Prud'homme van Reine 2008
Family Onslowiaceae Draisma & Prud'homme van Reine 2001
Order Sphacelariales Migula 1909
Family Cladostephaceae Oltmanns 1922
Family Lithodermataceae Hauck 1883
Family Phaeostrophiaceae Kawai et al. 2005
Family Sphacelariaceae Decaisne 1842
Family Sphacelodermaceae Draisma, Prud'homme & Kawai 2010
Family Stypocaulaceae Oltmanns 1922
Order Syringodermatales Henry 1984
Family Syringodermataceae Henry 1984
Subclass Fucophycidae Cavalier-Smith 1986
Order Ascoseirales Petrov1964 emend. Moe & Henry 1982
Family Ascoseiraceae Skottsberg 1907
Order Asterocladales T.Silberfeld et al. 2011
Family Asterocladaceae Silberfeld et al. 2011
Order Desmarestiales Setchell & Gardner 1925
Family Arthrocladiaceae Chauvin 1842
Family Desmarestiaceae (Thuret) Kjellman 1880
Order Ectocarpales Bessey 1907 emend. Rousseau & Reviers 1999a [Chordariales Setchell & Gardner 1925; Dictyosiphonales Setchell & Gardner 1925; Scytosiphonales Feldmann 1949]
Family Acinetosporaceae Hamel ex Feldmann 1937 [Pylaiellaceae; Pilayellaceae]
Family Adenocystaceae Rousseau et al. 2000 emend. Silberfeld et al. 2011 [Chordariopsidaceae]
Family Chordariaceae Greville 1830 emend. Peters & Ramírez 2001 [Myrionemataceae]
Family Ectocarpaceae Agardh 1828 emend. Silberfeld et al. 2011
Family Petrospongiaceae Racault et al. 2009
Family Scytosiphonaceae Ardissone & Straforello 1877 [Chnoosporaceae Setchell & Gardner 1925]
Order Fucales Bory de Saint-Vincent 1827 [Notheiales Womersley 1987; Durvillaeales Petrov 1965]
Family Bifurcariopsidaceae Cho et al. 2006
Family Durvillaeaceae (Oltmanns) De Toni 1891
Family Fucaceae Adanson 1763
Family Himanthaliaceae (Kjellman) De Toni 1891
Family Hormosiraceae Fritsch 1945
Family Notheiaceae Schmidt 1938
Family Sargassaceae Kützing 1843 [Cystoseiraceae De Toni 1891]
Family Seirococcaceae Nizamuddin 1987
Family Xiphophoraceae Cho et al. 2006
Order Laminariales Migula 1909 [Phaeosiphoniellales Silberfeld, Rousseau & Reviers 2014 ord. nov. prop.]
Family Agaraceae Postels & Ruprecht 1840 [Costariaceae]
Family Akkesiphycaceae Kawai & Sasaki 2000
Family Alariaceae Setchell & Gardner 1925
Family Aureophycaceae Kawai & Ridgway 2013
Family Chordaceae Dumortier 1822
Family Laminariaceae Bory de Saint-Vincent 1827 [Arthrothamnaceae Petrov 1974]
Family Lessoniaceae Setchell & Gardner 1925
Family Pseudochordaceae Kawai & Kurogi 1985
Order Nemodermatales Parente et al. 2008
Family Nemodermataceae Kuckuck ex Feldmann 1937
Order Phaeosiphoniellales Silberfeld, Rousseau & Reviers 2014
Family Phaeosiphoniellaceae Phillips et al. 2008
Order Ralfsiales Nakamura ex Lim & Kawai 2007
Family Mesosporaceae Tanaka & Chihara 1982
Family Neoralfsiaceae Lim & Kawai 2007
Family Ralfsiaceae Farlow 1881 [Heterochordariaceae Setchell & Gardner 1925]
Order Scytothamnales Peters & Clayton 1998 emend. Silberfeld et al. 2011
Family Asteronemataceae Silberfeld et al. 2011
Family Bachelotiaceae Silberfeld et al. 2011
Family Splachnidiaceae Mitchell & Whitting 1892 [Scytothamnaceae Womersley 1987]
Order Sporochnales Sauvageau 1926
Family Sporochnaceae Greville 1830
Order Tilopteridales Bessey 1907 emend. Phillips et al. 2008 [Cutleriales Bessey 1907]
Family Cutleriaceae Griffith & Henfrey 1856
Family Halosiphonaceae Kawai & Sasaki 2000
Family Phyllariaceae Tilden 1935
Family Stschapoviaceae Kawai 2004
Family Tilopteridaceae Kjellman 1890
Life cycle
Most brown algae, with the exception of the Fucales, perform sexual reproduction through sporic meiosis. Between generations, the algae go through separate sporophyte (diploid) and gametophyte (haploid) phases. The sporophyte stage is often the more visible of the two, though some species of brown algae have similar diploid and haploid phases. Free floating forms of brown algae often do not undergo sexual reproduction until they attach themselves to substrate. The haploid generation consists of male and female gametophytes. The fertilization of egg cells varies between species of brown algae, and may be isogamous, oogamous, or anisogamous. Fertilization may take place in the water with eggs and motile sperm, or within the oogonium itself.
Certain species of brown algae can also perform asexual reproduction through the production of motile diploid zoospores. These zoospores form in plurilocular sporangium, and can mature into the sporophyte phase immediately.
In a representative species Laminaria, there is a conspicuous diploid generation and smaller haploid generations. Meiosis takes place within several unilocular sporangium along the algae's blade, each one forming either haploid male or female zoospores. The spores are then released from the sporangia and grow to form male and female gametophytes. The female gametophyte produces an egg in the oogonium, and the male gametophyte releases motile sperm that fertilize the egg. The fertilized zygote then grows into the mature diploid sporophyte.
In the order Fucales, sexual reproduction is oogamous, and the mature diploid is the only form for each generation. Gametes are formed in specialized conceptacles that occur scattered on both surfaces of the receptacle, the outer portion of the blades of the parent plant. Egg cells and motile sperm are released from separate sacs within the conceptacles of the parent algae, combining in the water to complete fertilization. The fertilized zygote settles onto a surface and then differentiates into a leafy thallus and a finger-like holdfast. Light regulates differentiation of the zygote into blade and holdfast.(by samay the great )
Ecology
Brown algae have adapted to a wide variety of marine ecological niches including the tidal splash zone, rock pools, the whole intertidal zone and relatively deep near shore waters. They are an important constituent of some brackish water ecosystems, and have colonized freshwater on a minimum of six known occasions. A large number of Phaeophyceae are intertidal or upper littoral, and they are predominantly cool and cold water organisms that benefit from nutrients in up welling cold water currents and inflows from land; Sargassum being a prominent exception to this generalisation.
Brown algae growing in brackish waters are almost solely asexual.
Chemistry
Brown algae have a value in the range of −30.0‰ to −10.5‰, in contrast with red algae and greens. This reflects their different metabolic pathways.
They have cellulose walls with alginic acid and also contain the polysaccharide fucoidan in the amorphous sections of their cell walls. A few species (of Padina) calcify with aragonite needles.
In addition to alginates, fucoidan and cellulose, the carbohydrate composition of brown algae consists of mannitol, laminarin and glucan.
The photosynthetic system of brown algae is made of a P700 complex containing chlorophyll a. Their plastids also contain chlorophyll c and carotenoids (the most widespread of those being fucoxanthin).
Brown algae produce a specific type of tannin called phlorotannins in higher amounts than red algae do.
Importance and uses
Brown algae include a number of edible seaweeds. All brown algae contain alginic acid (alginate) in their cell walls, which is extracted commercially and used as an industrial thickening agent in food and for other uses. One of these products is used in lithium-ion batteries. Alginic acid is used as a stable component of a battery anode. This polysaccharide is a major component of brown algae, and is not found in land plants.
Alginic acid can also be used in aquaculture. For example, alginic acid enhances the immune system of rainbow trout. Younger fish are more likely to survive when given a diet with alginic acid.
Brown algae including kelp beds also fix a significant portion of the earth's carbon dioxide yearly through photosynthesis. Additionally, they can store a great amount of carbon dioxide which can help us in the fight against climate change.
Sargachromanol G, an extract of Sargassum siliquastrum, has been shown to have anti-inflammatory effects.
Edible brown algae
Kelp (Laminariales)
Arame (Eisenia bicyclis)
Badderlocks (Alaria esculenta)
Cochayuyo (Durvillaea antarctica)
Ecklonia cava
Kombu (Saccharina japonica)
Oarweed (Laminaria digitata)
Sea palm Postelsia palmaeformis
Sea whip (Nereocystis luetkeana)
Sugar kelp (Saccharina latissima)
Wakame (Undaria pinnatifida)
Hirome (Undaria undarioides)
Grapestone (Mastocarpus papillatus)
Fucales
Bladderwrack (Fucus vesiculosus)
Channelled wrack (Pelvetia canaliculata)
Hijiki or Hiziki (Sargassum fusiforme)
Limu Kala (Sargassum echinocarpum)
Sargassum
Sargassum cinetum
Sargassum vulgare
Sargassum swartzii
Sargassum myriocysum
Spiral wrack (Fucus spiralis)
Thongweed (Himanthalia elongata)
Ectocarpales
Mozuku (Cladosiphon okamuranus)
See also
Wrack (seaweed)
References
External links
Monterey Bay Flora
The Monterey Formation of California, University of California Museum of Paleontology
Phaeophyceae, National University of Ireland, Galway
Biological oceanography
Tithonian first appearances
Extant Late Jurassic first appearances | Brown algae | Biology | 6,102 |
3,322,454 | https://en.wikipedia.org/wiki/Glyoxylate%20cycle | The glyoxylate cycle, a variation of the tricarboxylic acid cycle, is an anabolic pathway occurring in plants, bacteria, protists, and fungi. The glyoxylate cycle centers on the conversion of acetyl-CoA to succinate for the synthesis of carbohydrates. In microorganisms, the glyoxylate cycle allows cells to use two carbons (C2 compounds), such as acetate, to satisfy cellular carbon requirements when simple sugars such as glucose or fructose are not available. The cycle is generally assumed to be absent in animals, with the exception of nematodes at the early stages of embryogenesis. In recent years, however, the detection of malate synthase (MS) and isocitrate lyase (ICL), key enzymes involved in the glyoxylate cycle, in some animal tissue has raised questions regarding the evolutionary relationship of enzymes in bacteria and animals and suggests that animals encode alternative enzymes of the cycle that differ in function from known MS and ICL in non-metazoan species.
Plants as well as some algae and bacteria can use acetate as the carbon source for the production of carbon compounds. Plants and bacteria employ a modification of the TCA cycle called the glyoxylate cycle to produce four carbon dicarboxylic acid from two carbon acetate units. The glyoxylate cycle bypasses the two oxidative decarboxylation reactions of the TCA cycle and directly converts isocitrate through isocitrate lyase and malate synthase into malate and succinate.
The glyoxylate cycle was discovered in 1957 at the University of Oxford by Sir Hans Kornberg and his mentor Hans Krebs, resulting in a Nature paper Synthesis of Cell Constituents from C2-Units by a Modified Tricarboxylic Acid Cycle.
Similarities with TCA cycle
The glyoxylate cycle uses five of the eight enzymes associated with the tricarboxylic acid cycle: citrate synthase, aconitase, succinate dehydrogenase, fumarase, and malate dehydrogenase. The two cycles differ in that in the glyoxylate cycle, isocitrate is converted into glyoxylate and succinate by isocitrate lyase (ICL) instead of into α-ketoglutarate. This bypasses the decarboxylation steps that take place in the citric acid cycle (TCA cycle), allowing simple carbon compounds to be used in the later synthesis of macromolecules, including glucose. Glyoxylate is subsequently combined with acetyl-CoA to produce malate, catalyzed by malate synthase. Malate is also formed in parallel from succinate by the action of succinate dehydrogenase and fumarase.
Role in gluconeogenesis
Fatty acids from lipids are commonly used as an energy source by vertebrates as fatty acids are degraded through beta oxidation into acetate molecules. This acetate, bound to the active thiol group of coenzyme A, enters the citric acid cycle (TCA cycle) where it is fully oxidized to carbon dioxide. This pathway thus allows cells to obtain energy from fat. To use acetate from fat for biosynthesis of carbohydrates, the glyoxylate cycle, whose initial reactions are identical to the TCA cycle, is used.
Cell-wall containing organisms, such as plants, fungi, and bacteria, require very large amounts of carbohydrates during growth for the biosynthesis of complex structural polysaccharides, such as cellulose, glucans, and chitin. In these organisms, in the absence of available carbohydrates (for example, in certain microbial environments or during seed germination in plants), the glyoxylate cycle permits the synthesis of glucose from lipids via acetate generated in fatty acid β-oxidation.
The glyoxylate cycle bypasses the steps in the citric acid cycle where carbon is lost in the form of CO2. The two initial steps of the glyoxylate cycle are identical to those in the citric acid cycle: acetate → citrate → isocitrate. In the next step, catalyzed by the first glyoxylate cycle enzyme, isocitrate lyase, isocitrate undergoes cleavage into succinate and glyoxylate (the latter gives the cycle its name). Glyoxylate condenses with acetyl-CoA (a step catalyzed by malate synthase), yielding malate. Both malate and oxaloacetate can be converted into phosphoenolpyruvate, which is the product of phosphoenolpyruvate carboxykinase, the first enzyme in gluconeogenesis. The net result of the glyoxylate cycle is therefore the production of glucose from fatty acids. Succinate generated in the first step can enter into the citric acid cycle to eventually form oxaloacetate.
Function in organisms
Plants
In plants the glyoxylate cycle occurs in special peroxisomes which are called glyoxysomes. This cycle allows seeds to use lipids as a source of energy to form the shoot during germination. The seed cannot produce biomass using photosynthesis because of lack of an organ to perform this function. The lipid stores of germinating seeds are used for the formation of the carbohydrates that fuel the growth and development of the organism.
The glyoxylate cycle can also provide plants with another aspect of metabolic diversity. This cycle allows plants to take in acetate both as a carbon source and as a source of energy. Acetate is converted to acetyl CoA (similar to the TCA cycle). This acetyl CoA can proceed through the glyoxylate cycle, and some succinate is released during the cycle. The four carbon succinate molecule can be transformed into a variety of carbohydrates through combinations of other metabolic processes; the plant can synthesize molecules using acetate as a source for carbon. The acetyl CoA can also react with glyoxylate to produce some NADPH from NADP+, which is used to drive energy synthesis in the form of ATP later in the electron transport chain.
Pathogenic fungi
The glyoxylate cycle may serve an entirely different purpose in some species of pathogenic fungi. The levels of the main enzymes of the glyoxylate cycle, ICL and MS, are greatly increased upon contact with a human host. Mutants of a particular species of fungi that lacked ICL were also significantly less virulent in studies with mice compared to the wild type. The exact link between these two observations is still being explored, but it can be concluded that the glyoxylate cycle is a significant factor in the pathogenesis of these microbes.
Vertebrates
Vertebrates were once thought to be unable to perform this cycle because there was no evidence of its two key enzymes, isocitrate lyase and malate synthase. However, some research suggests that this pathway may exist in some, if not all, vertebrates.
Specifically, some studies show evidence of components of the glyoxylate cycle existing in significant amounts in the liver tissue of chickens. Data such as these support the idea that the cycle could theoretically occur in even the most complex vertebrates. Other experiments have also provided evidence that the cycle is present among certain insect and marine invertebrate species, as well as strong evidence of the cycle's presence in nematode species. However, other experiments refute this claim. Some publications conflict on the presence of the cycle in mammals: for example, one paper has stated that the glyoxylate cycle is active in hibernating bears, but this report was disputed in a later paper. Evidence exists for malate synthase activity in humans due to a dual functional malate/B-methylmalate synthase of mitochondrial origin called CLYBL expressed in brown fat and kidney. Vitamin D may regulate this pathway in vertebrates.
Inhibition of the glyoxylate cycle
Due to the central role of the glyoxylate cycle in the metabolism of pathogenic species including fungi and bacteria, enzymes of the glyoxylate cycle are current inhibition targets for the treatment of diseases. Most reported inhibitors of the glyoxylate cycle target the first enzyme of the cycle (ICL). Inhibitors were reported for Candida albicans for potential use as antifungal agents. The mycobacterial glyoxylate cycle is also being targeted for potential treatments of tuberculosis.
Engineering concepts
The prospect of engineering various metabolic pathways into mammals which do not possess them is a topic of great interest for bio-engineers today. The glyoxylate cycle is one of the pathways which engineers have attempted to manipulate into mammalian cells. This is primarily of interest for engineers in order to increase the production of wool in sheep, which is limited by the access to stores of glucose. By introducing the pathway into sheep, the large stores of acetate in cells could be used in order to synthesize glucose through the cycle, allowing for increased production of wool. Mammals are incapable of executing the pathway due to the lack of two enzymes, isocitrate lyase and malate synthase, which are needed in order for the cycle to take place. It is believed by some that the genes to produce these enzymes, however, are pseudogenic in mammals, meaning that the gene is not necessarily absent, rather, it is merely "turned off".
In order to engineer the pathway into cells, the genes responsible for coding for the enzymes had to be isolated and sequenced, which was done using the bacteria E.coli, from which the AceA gene, responsible for encoding for isocitrate lyase, and the AceB gene, responsible for encoding for malate synthase were sequenced. Engineers have been able to successfully incorporate the AceA and AceB genes into mammalian cells in culture, and the cells were successful in translating and transcribing the genes into the appropriate enzymes, proving that the genes could successfully be incorporated into the cell’s DNA without damaging the functionality or health of the cell. However, being able to engineer the pathway into transgenic mice has proven to be difficult for engineers. While the DNA has been expressed in some tissues, including the liver and small intestine in test animals, the level of expression is not high, and not found to be statistically significant. In order to successfully engineer the pathway, engineers would have to fuse the gene with promoters which could be regulated in order to increase the level of expression, and have the expression in the right cells, such as epithelial cells.
Efforts to engineer the pathway into more complex animals, such as sheep, have not been effective. This illustrates that much more research needs to be done on the topic, and suggests it is possible that a high expression of the cycle in animals would not be tolerated by the chemistry of the cell. Incorporating the cycle into mammals will benefit from advances in nuclear transfer technology, which will enable engineers to examine and access the pathway for functional integration within the genome before its transfer to animals.
There are possible benefits, however, to the cycle's absence in mammalian cells. The cycle is present in microorganisms that cause disease but is absent in mammals, for example humans. There is a strong plausibility of the development of antibiotics that would attack the glyoxylate cycle, which would kill the disease-causing microorganisms that depend on the cycle for their survival, yet would not harm humans where the cycle, and thus the enzymes that the antibiotic would target, are absent.
See also
Citric acid cycle (Tricarboxylic acid cycle)
References
External links
Comparative Analysis of Glyoxylate Cycle Key Enzyme Isocitrate Lyase from Organisms of Different Systematic Groups
Biochemical reactions
Carbohydrate metabolism
Metabolic pathways | Glyoxylate cycle | Chemistry,Biology | 2,537 |
18,033,743 | https://en.wikipedia.org/wiki/Russula%20claroflava | Russula claroflava, commonly known as the yellow russula, yellow swamp russula or yellow swamp brittlegill, is a basidiomycete mushroom of the genus Russula. It is found in wet places under birch and aspen woodlands across Europe and North America. It has a yellow cap, white gills and stipe and bruises grey. It is mild-tasting and regarded as good to eat.
Taxonomy
It was described in 1888 by William Bywater Grove, based on a specimen from Sutton Park in the English Midlands. Its specific epithet is derived from the Latin clarus 'bright' or 'clear', and flava 'light yellow'.
Description
This medium-sized member of the genus Russula has a cap that is an egg-yolk yellow. Measuring 4–10 cm (1.5 4 in) in diameter, it is slightly sticky when moist, and leaves and other debris often stick to it. There is usually a slight depression in the centre of mature specimens, with the margin becoming furrowed. The cap is half peeling. The high stem is white, fairly firm, straight and 1–2 cm thick. Its gills are pale ochre, and are adnexed to almost free. All parts turn dark grey on aging or bruising. The smell is fruity and the spore print is pale ochre, and the oval warty spores average 9.5 x 8 μm. The edible but acrid Russula ochroleuca resembles this species, but has a duller yellow cap.
Distribution and habitat
Russula claroflava appears in summer and autumn, usually with birch (Betula), or aspen (Populus), on heaths and moors, preferring damp places near ponds or lakes, often occurring in sphagnum. It is occasionally found in drier places. It occurs in Britain, across northern Europe, and throughout North America.
Edibility
This mushroom is edible and good, with a mild taste, both in Europe and North America.
See also
List of Russula species
References
Cited literature
Marcel Bon, The Mushrooms and Toadstools of Britain and North Western Europe.
Courtecuisse and Duhem, Mushrooms and Toadstools of Britain and Europe.
claroflava
Edible fungi
Fungi described in 1888
Fungi of Europe
Fungi of North America
Fungus species | Russula claroflava | Biology | 471 |
13,056,805 | https://en.wikipedia.org/wiki/Cephaloridine | Cephaloridine (or cefaloridine) is a first-generation semisynthetic derivative of antibiotic cephalosporin C. It is a Beta lactam antibiotic, like penicillin. Its chemical structure contains cephems,carboxyl groups and a pyridinium ring.
Cephaloridine is mainly used in veterinary practice. It is unique among cephalosporins in that it exists as a zwitterion.
History
Since the discovery of cephalosporins P, N and C in 1948 there have been many studies describing the antibiotic action of cephalosporins and the possibility to synthesize derivatives. Hydrolysis of cephalosporin C, isolation of 7-aminocephalosporanic acid and the addition of side chains opened the possibility to produce various semi-synthetic cephalosporins. In 1962, cephalothin and cephaloridine were introduced.
Cephaloridine was briefly popular because it tolerated intramuscularly and attained higher and more sustained levels in blood than cephalothin. However, it binds to proteins to a much lesser extent than cephalothin. Because it is also poorly absorbed after oral administration the use of this drug for humans declined rapidly, especially since the second generation of cephalosporins was introduced in the 1970s. Today, it is more commonly used in veterinary practice to treat mild to severe bacterial infections caused by penicillin resistant and penicillin sensitive Staphylococcus aureus, Escherichia coli, Streptococcus pyogenes, Streptococcus pneumoniae, Bacillus subtilis, Klebsiella, Clostridium diphtheriae, Salmonella and Shigella. Interest in studying cephalosporins was brought about by some unusual properties of cephaloridine. This antibiotic stands in sharp contrast to various other cephalosporins and to the structurally related penicillins in undergoing little or no net secretion by the mammalian kidney. Cephaloridine is, however, highly cytotoxic to the proximal renal tubule, the segment of the nephron responsible for the secretion of organic anions, including para-am-minohippurate (PAH), as well as the various penicillin and cephalosporin antibiotics. The cytotoxicity of cephaloridine is completely prevented by probenecid and several other inhibitors of organic anion transport, including the nearly nontoxic cephalothin.
Structure & reactivity
Cephaloridine is a cephalosporin compound with pyridinium-1-ylmethyl and 2-thienylacetamido side groups. The molecular nucleus, of which all cephalosporins are derivatives, is A3-7-aminocephalosporanic acid. Conformations around the β-lactam rings are quite similar to the molecular nucleus of penicillin, while those at the carboxyl group exocyclic to the dihydrothiazine and thiazolidine rings respectively are different.
Synthesis
Cephaloridine can be synthesised from Cephalotin and pyridine by deacetylation. This can be done by heating an aqueous mixture of cephalotin, thiocyanate, pyridine and phosphoric acid for several hours. After cooling, diluting with water, and adjusting the pH with mineral acid, cephaloridine thiocyanate salt precipitates. This can be purified and converted to cephaloridine by pH adjustment or by interaction with ion-exchange resin.
Clinical use of cephaloridine
Before the 1970s, cephaloridine was used to treat patients with urinary tract infections. Besides the drugs has been used successfully in the treatment of various lower respiratory tract infections. Cephaloridine was very effective to cure pneumococcal pneumonia. It has a high clinical and bacteriological rate of success in staphylococcal and streptococcal infections.
Kinetics
Absorption
Cephaloridine is easily absorbed after intramuscular injection and poorly absorbed from the gastrointestinal tract.
Distribution
The minor pathway of elimination is biliary excretion. When the blood serum concentration is 24 μg/mL, the corresponding biliary concentration is 10 μg/mL. In the spinal fluid the concentration of cephaloridine is 6–12% of the concentration in the blood and serum.
Cephaloridine is distributed well into the liver, stomach wall, lung and spleen and is also found in fresh wounds one hour after injection. The concentration in the wound will decrease as the wound age increases. However, the drug is poorly penetrated into the cerebrospinal fluid and is found in a much smaller amount in the cerebral cortex.
Pregnancy
When cephaloridine is administered to pregnant women, the drug crosses the placenta. Cephaloridine concentrations can be measured in the serum of the newborn up to 22 hours after labor, and can reach a level of 54% of the concentration in the maternal serum. When given an intramuscular dose of 1 g, a peak occurs in the cord blood after 4 hours. In amniotic fluid, the concentration takes about 3 hours to reach its antibacterial effect.
Metabolism and excretion
Urine specimens showed that no other microbiologically active metabolites were present except cephaloridine and that cephaloridine is excreted unchanged.
Renal clearances were reported to be 146–280 ml/min, a plasma clearance of 167 ml/min/1,73m2 and a renal clearance of 125 ml/min/1,73m2. A serum half-life of 1,1-1,5 hour and a volume of distribution of 16 liters were reported.
Pharmacokinetics
Pharmacokinetic analysis is not possible because appropriate data is not published. The physicochemical properties are almost the same as the other cephalosporins, therefore the pharmacokinetics are comparable.
Adverse effects
Toxicity
Cephaloridine can cause kidney damage in humans, since it is actively taken up from the blood by the proximal tubular cells via an organic anion transporter (OAT) in the basolateral membrane. Organic anions are secreted through the proximal tubular cells via unidirectional transcellular transport. The organic anions are taken up from the blood into the cells across the basolateral membrane and extruded across the brush border membrane into the tubular fluid. Cephaloridine is a substrate for OAT1 and thus can be transported into the proximal tubular cells, which form the renal cortex. The drugs, however, cannot move readily across the luminal membrane since it is a zwitterion. The cationic group (pyridinium ring) of the compound probably inhibits the efflux through the membrane. This results in an accumulation of cephaloridine in the renal cortex of the kidney, causing damage and necrosis of the S2 segment of the tubule. However, there are no adverse effects on renal function if serum levels of cephaloridine are maintained between 20 and 80 μg/mL.
Metabolism
Cephaloridine is excreted in the urine without undergoing metabolism.
It inhibits organic ion transport in the kidney. This process is preceded by the lipid peroxidation. Thereafter, probably a combination of events, such as formation of a reactive intermediate, a free radical and stimulation of lipid peroxidation, lead to peroxidative damage to cell membranes and mitochondria. It is not yet clear whether metabolic activation by cytochromes P-450, chemical rearrangements, reductive activation or all these actions are involved.
The hypotheses made about the mechanism of action causing the toxicity of cephaloridine are:
Reactive metabolites are formed by cytochromes P-450 or emerge from destabilization of the β-lactam ring. Metabolic activation of the drugs might take place via cytochromes P-450, producing reactive metabolites. This hypothesis is based on the behaviour of some inhibitors of CYP450, which decrease the toxicity, and some inducers of the monooxygenases which increase toxicity. It could also be possible that a reactive intermediate is formed due to the unstable β-lactam ring. The pyridinium side-group of cephaloridine has unstable bonds to the core of the compound (in comparison with other cephalosporins). When this side-group leaves, the β-lactam ring is destabilized by intramolecular electron shifts. Thus, the leaving group creates a reactive product.
Both lipid peroxidation and oxidative stress can cause membrane damage. Lipid peroxidation and oxidative stress take place as lipid peroxidation products, such as malondialdehyde, have been detected. Reduced glutathione (GSH) and NADPH are both depleted. Consequently, GSSG cannot be reduced to GSH. This leads to an increased toxicity since oxidative stress cannot be reduced. In addition, nephrotoxicity is augmented by deficiency of selenium or tocopherol. The pyridinium side-group interacts with the reduced NADP in a redox cycle. It has been suggested that superoxide anion radicals and hydroxyl radicals may be formed and that lipid peroxidation could be responsible for the toxicity of cephaloridine.
Damage to the mitochondria and intracellular respiratory processes and reduced mitochondrial respiration can cause nephrotoxicity. The previously mentioned damages have been detected after exposure to cephalosporins. β-lactam antibiotics injure mitochondria by an attack on the metabolic substrate carriers of the inner membrane. Respiratory toxicity is caused by inactivation of mitochondrial anion substrate carriers.
Symptoms of kidney damage caused by cephaloridine
Some symptoms caused by cephaloridine are: asymptomatic, enzymuria, proteinuria, tubular necrosis, increased urea level in blood, anemia, increased hydrogen ion level in blood, fatigue, increased blood pressure, increased blood electrolyte level, kidney dysfunction, kidney damage, impaired body water balance and impaired electrolyte balance.
Complications caused by cephaloridine
Complications caused by the use of cephaloridine include seizures, coma, chronic kidney failure, acute kidney failure and death.
Treatment of kidney damage caused by cephaloridine
The damage of the kidneys can be treated by removing the toxin from the body, monitoring and supporting kidney function (dialysis if necessary) and, in severe cases, kidney transplant. Supportive therapy in the acute phase can be done by fluid, electrolyte and hypertension management. Longer term management includes monitoring of renal function, close management of high blood pressure. Furthermore, dietary management may include protein and sodium management, adequate hydration and phosphate and potassium restriction. In case of chronic kidney failure dietary management also includes erythropoietin agonists (since anaemia is associated with chronic kidney failure), phosphate binders (in case of hyperphosphatemia), calcium supplements, Vitamin D supplements and sodium bicarbonate (to correct the acid-base disturbance).
References
Cephalosporin antibiotics
Pyridinium compounds
Thiophenes
Zwitterions | Cephaloridine | Physics,Chemistry | 2,451 |
12,700,262 | https://en.wikipedia.org/wiki/Toroidal%20and%20poloidal%20coordinates | The terms toroidal and poloidal refer to directions relative to a torus of reference. They describe a three-dimensional coordinate system in which the poloidal direction follows a small circular ring around the surface, while the toroidal direction follows a large circular ring around the torus, encircling the central void.
The earliest use of these terms cited by the Oxford English Dictionary is by Walter M. Elsasser (1946) in the context of the generation of the Earth's magnetic field by currents in the core, with "toroidal" being parallel to lines of constant latitude and "poloidal" being in the direction of the magnetic field (i.e. towards the poles).
The OED also records the later usage of these terms in the context of toroidally confined plasmas, as encountered in magnetic confinement fusion. In the plasma context, the toroidal direction is the long way around the torus, the corresponding coordinate being denoted by in the slab approximation or or in magnetic coordinates; the poloidal direction is the short way around the torus, the corresponding coordinate being denoted by in the slab approximation or in magnetic coordinates. (The third direction, normal to the magnetic surfaces, is often called the "radial direction", denoted by in the slab approximation and variously , , , , or in magnetic coordinates.)
Example
As a simple example from the physics of magnetically confined plasmas, consider an axisymmetric system with circular, concentric magnetic flux surfaces of radius (a crude approximation to the magnetic field geometry in an early tokamak but topologically equivalent to any toroidal magnetic confinement system with nested flux surfaces) and denote the toroidal angle by and the poloidal angle by .
Then the toroidal/poloidal coordinate system relates to standard Cartesian coordinates by these transformation rules:
where .
The natural choice geometrically is to take , giving the toroidal and poloidal directions shown by the arrows in the figure above, but this makes a left-handed curvilinear coordinate system. As it is usually assumed in setting up flux coordinates for describing magnetically confined plasmas that the set forms a right-handed coordinate system, , we must either reverse the poloidal direction by taking , or reverse the toroidal direction by taking . Both choices are used in the literature.
Kinematics
To study single particle motion in toroidally confined plasma devices, velocity and acceleration vectors must be known. Considering the natural choice , the unit vectors of toroidal and poloidal coordinates system can be expressed as:
according to Cartesian coordinates. The position vector is expressed as:
The velocity vector is then given by:
and the acceleration vector is:
See also
Toroidal coordinates
Torus
Zonal and poloidal
Poloidal–toroidal decomposition
Zonal flow (plasma)
References
Coordinate systems | Toroidal and poloidal coordinates | Mathematics | 567 |
2,362,494 | https://en.wikipedia.org/wiki/Matter%20creation | Even restricting the discussion to physics, scientists do not have a unique definition of what matter is. In the currently known particle physics, summarised by the standard model of elementary particles and interactions, it is possible to distinguish in an absolute sense particles of matter and particles of antimatter. This is particularly easy for those particles that carry electric charge, such as electrons, protons or quarks, while the distinction is more subtle in the case of neutrinos, fundamental elementary particles that do not carry electric charge. In the standard model, it is not possible to create a net amount of matter particles—or more precisely, it is not possible to change the net number of leptons or of quarks in any perturbative reaction among particles. This remark is consistent with all existing observations.
However, similar processes are not considered to be impossible and are expected in other models of the elementary particles, that extend the standard model. They are necessary in speculative theories that aim to explain the cosmic excess of matter over antimatter, such as leptogenesis and baryogenesis. They could even manifest themselves in laboratory as proton decay or as creations of electrons in the so-called neutrinoless double beta decay. The latter case occurs if the neutrinos are Majorana particles, being at the same time matter and antimatter, according to the definition given just above.
In a wider sense, one can use the word matter simply to refer to fermions. In this sense, matter and antimatter particles (such as an electron and a positron) are identified beforehand. The process inverse to particle annihilation can be called matter creation; more precisely, we are considering here the process obtained under time reversal of the annihilation process. This process is also known as pair production, and can be described as the conversion of light particles (i.e., photons) into one or more massive particles. The most common and well-studied case is the one where two photons convert into an electron–positron pair.
Photon pair production
Because of momentum conservation laws, the creation of a pair of fermions (matter particles) out of a single photon cannot occur. However, matter creation is allowed by these laws when in the presence of another particle (another boson, or even a fermion) which can share the primary photon's momentum. Thus, matter can be created out of two photons.
The law of conservation of energy sets a minimum photon energy required for the creation of a pair of fermions: this threshold energy must be greater than the total rest energy of the fermions created. To create an electron-positron pair, the total energy of the photons, in the rest frame, must be at least 2mec2 = 2 × = (me is the mass of one electron and c is the speed of light in vacuum), an energy value that corresponds to soft gamma ray photons. The creation of a much more massive pair, like a proton and antiproton, requires photons with energy of more than (hard gamma ray photons).
The first published calculations of the rate of e+–e− pair production in photon-photon collisions were done by Lev Landau in 1934. It was predicted that the process of e+–e− pair creation (via collisions of photons) dominates in collision of ultra-relativistic charged particles—because those photons are radiated in narrow cones along the direction of motion of the original particle, greatly increasing photon flux.
In high-energy particle colliders, matter creation events have yielded a wide variety of exotic heavy particles precipitating out of colliding photon jets (see two-photon physics). Currently, two-photon physics studies creation of various fermion pairs both theoretically and experimentally (using particle accelerators, air showers, radioactive isotopes, etc.).
It is possible to create all fundamental particles in the standard model, including quarks, leptons and bosons using photons of varying energies above some minimum threshold, whether directly (by pair production), or by decay of the intermediate particle (such as a W− boson decaying to form an electron and an electron-antineutrino).
As shown above, to produce ordinary baryonic matter out of a photon gas, this gas must not only have a very high photon density, but also be very hot – the energy (temperature) of photons must obviously exceed the rest mass energy of the given matter particle pair. The threshold temperature for production of electrons is about 1010 K, 1013 K for protons and neutrons, etc. According to the Big Bang theory, in the early universe, mass-less photons and massive fermions would inter-convert freely. As the photon gas expanded and cooled, some fermions would be left over (in extremely small amounts ~10−10) because low energy photons could no longer break them apart. Those left-over fermions would have become the matter we see today in the universe around us.
See also
Annihilation
Available energy
Pair production
Schwinger limit
References
Particle physics | Matter creation | Physics | 1,067 |
14,873,938 | https://en.wikipedia.org/wiki/FOSL2 | Fos-related antigen 2 (FRA2) is a protein that in humans is encoded by the FOSL2 gene.
Function
The Fos gene family consists of 4 members: c-Fos, FOSB, FOSL1, and FOSL2. These genes encode leucine zipper proteins that can dimerize with proteins of the JUN family, thereby forming the transcription factor complex AP-1. As such, the FOS proteins have been implicated as regulators of cell proliferation, differentiation, and transformation.
See also
AP-1 (transcription factor)
References
Further reading
External links
Transcription factors | FOSL2 | Chemistry,Biology | 126 |
10,582,945 | https://en.wikipedia.org/wiki/Meta%20%28chemistry%29 | In chemistry, meta is a prefix, used for systematic names in IUPAC nomenclature. It has several meanings.
In organic chemistry, meta indicates the positions of substituents in aromatic cyclic compounds. The substituents have the 1,3-positions, for example in resorcinol.
Meta may also denote the dehydrated form of an acid, salt or organic derivative in a series. For example:
metabisulfite:
metaphosphoric acid:
Meta-antimonic acid, the dehydrated form of antimonic acid (), is .
See also
Arene substitution patterns
References
Chemistry prefixes | Meta (chemistry) | Chemistry | 134 |
35,647,113 | https://en.wikipedia.org/wiki/Medal%20%22For%20the%20Tapping%20of%20the%20Subsoil%20and%20Expansion%20of%20the%20Petrochemical%20Complex%20of%20Western%20Siberia%22 | The Medal "For the Tapping of the Subsoil and Expansion of the Petrochemical Complex of Western Siberia" () was a civilian award of the Soviet Union established on July 28, 1978 by Decree of the Presidium of the Supreme Soviet of the USSR to recognise three years of dedicated work in developing the Petrochemical Complex of Western Siberia.
Medal statute
The Medal "For the Tapping of the Subsoil and Expansion of the Petrochemical Complex of Western Siberia" was awarded to active members in the underground exploration and development of the oil and gas complex of Western Siberia for selfless labour in the identification, exploration and development of the mining and industrial processing of oil and gas, for work in construction, in manufacturing, in housing and other civilian facilities, in building highways, in electricity, transport or other services to the oil and gas industries, as well as to employees of scientific, research or design organizations, of institutions and organizations, of the service sector, Party, Soviet, trade union or Komsomol organs of the oil and gas industry, who produced conscientious work and contributed to the development of the petrochemical complex of Western Siberia over a period of at least three years.
Recommendations for award of the Medal "For the Tapping of the Subsoil and Expansion of the Petrochemical Complex of Western Siberia" were made by the administrative heads of enterprises, institutions, organizations, party, trade union or Komsomol organizations or labour collectives and the executive committees of the District or City Council of People's Deputies. The names of the potential recipients were then forwarded to the various ministries and agencies overseeing the different companies and organisations which were working in the development of the petrochemical complex of Western Siberia for approval. The names of the recipients was then forwarded to the executive committees of the Tyumen or Tomsk oblasts Soviets of People's Deputies for award on behalf of the Presidium of the Supreme Soviet of the USSR and of the Presidium of the Supreme Soviet of the RSFSR.
The Medal "For the Tapping of the Subsoil and Expansion of the Petrochemical Complex of Western Siberia" was worn on the left side of the chest and in the presence of other medals of the USSR, immediately after the Medal "For Transforming the Non-Black Earth of the RSFSR". If worn in the presence of awards of the Russian Federation, the latter have precedence.
Each medal came with an attestation of award, this attestation came in the form of a small 8 cm by 11 cm cardboard booklet bearing the award's name, the recipient's particulars and an official stamp and signature on the inside.
Medal description
The Medal "For the Tapping of the Subsoil and Expansion of the Petrochemical Complex of Western Siberia" was a 32 mm in diameter circular brass medal. On its obverse, in the right half, the relief image of a sickle over a vertical hammer, in the background, the relief images of two oil rigs at center, two gas tanks at left, a tractor and piping at lower center, at the bottom a small relief five pointed star, along the medal circumference, the relief inscription "For the tapping of the subsoil and expansion of the petrochemical complex of Western Siberia" (). On the reverse, in the central upper half, a relief five pointed star emitting rays from between its arms forming an inversed pentagon, superimposed over the star, the relief inscription "USSR" (), at the bottom, crossed laurel and oak branches.
The Medal "For the Tapping of the Subsoil and Expansion of the Petrochemical Complex of Western Siberia" was secured to a standard Soviet pentagonal mount by a ring through the medal suspension loop. The mount was covered by a 24 mm wide overlapping green silk moiré ribbon with a 6 mm wide central blue stripe bordered on both sides by 2 mm black stripes themselves bordered on the outside by 1 mm wide white stripes.
Recipients (partial list)
The individuals below were recipients of the Medal "For the Tapping of the Subsoil and Expansion of the Petrochemical Complex of Western Siberia".
Ivan Yegorovich Korovin
Vladimir Leonidovich Bogdanov
Aleksandr Yakovlevich Kosyakov
Andrei Philipovich Mukha
Viktor Yanukovych Redikultsev
Aleksandr Viktorovich Sarychev
Solokhin Valentin Fedorovich
Valentina Fedorovna Arova
Dmitry Vasilyevich Makuschenko
Alexander Karlovich Shpeter
Sergey Evgenevich Korepanov
Irek Saitgalievich Kharisov
Tamara Fedorovna Bortsova
Vladimir Dmitrievich Bykovsky
Igor Vladimirovich Belousenko
See also
Orders, decorations, and medals of the Soviet Union
References
External links
Legal Library of the USSR
The Russian Gazette
Civil awards and decorations of the Soviet Union
Awards established in 1978
1978 establishments in the Soviet Union
Energy in the Soviet Union
Petrochemical industry | Medal "For the Tapping of the Subsoil and Expansion of the Petrochemical Complex of Western Siberia" | Chemistry | 1,008 |
855,776 | https://en.wikipedia.org/wiki/Einstein%E2%80%93Hilbert%20action | The Einstein–Hilbert action in general relativity is the action that yields the Einstein field equations through the stationary-action principle. With the metric signature, the gravitational part of the action is given as
where is the determinant of the metric tensor matrix, is the Ricci scalar, and is the Einstein gravitational constant ( is the gravitational constant and is the speed of light in vacuum). If it converges, the integral is taken over the whole spacetime. If it does not converge, is no longer well-defined, but a modified definition where one integrates over arbitrarily large, relatively compact domains, still yields the Einstein equation as the Euler–Lagrange equation of the Einstein–Hilbert action. The action was proposed by David Hilbert in 1915 as part of his application of the variational principle to a combination of gravity and electromagnetism.
Discussion
Deriving equations of motion from an action has several advantages. First, it allows for easy unification of general relativity with other classical field theories (such as Maxwell theory), which are also formulated in terms of an action. In the process, the derivation identifies a natural candidate for the source term coupling the metric to matter fields. Moreover, symmetries of the action allow for easy identification of conserved quantities through Noether's theorem.
In general relativity, the action is usually assumed to be a functional of the metric (and matter fields), and the connection is given by the Levi-Civita connection. The Palatini formulation of general relativity assumes the metric and connection to be independent, and varies with respect to both independently, which makes it possible to include fermionic matter fields with non-integer spin.
The Einstein equations in the presence of matter are given by adding the matter action to the Einstein–Hilbert action.
Derivation of Einstein field equations
Suppose that the full action of the theory is given by the Einstein–Hilbert term plus a term describing any matter fields appearing in the theory.
The stationary-action principle then tells us that to recover a physical law, we must demand that the variation of this action with respect to the inverse metric be zero, yielding
.
Since this equation should hold for any variation , it implies that
is the equation of motion for the metric field. The right hand side of this equation is (by definition) proportional to the stress–energy tensor,
.
To calculate the left hand side of the equation we need the variations of the Ricci scalar and the determinant of the metric. These can be obtained by standard textbook calculations such as the one given below, which is strongly based on the one given in Carroll (2004).
Variation of the Ricci scalar
The variation of the Ricci scalar follows from varying the Riemann curvature tensor, and then the Ricci curvature tensor.
The first step is captured by the Palatini identity
.
Using the product rule, the variation of the Ricci scalar then becomes
where we also used the metric compatibility , and renamed the summation indices in the last term.
When multiplied by , the term becomes a total derivative, since for any vector and any tensor density , we have
or .
By Stokes' theorem, this only yields a boundary term when integrated. The boundary term is in general non-zero, because the integrand depends not only on but also on its partial derivatives ; see the article Gibbons–Hawking–York boundary term for details. However, when the variation of the metric vanishes in a neighbourhood of the boundary or when there is no boundary, this term does not contribute to the variation of the action. Thus, we can forget about this term and simply obtain
at events not in the closure of the boundary.
Variation of the determinant
Jacobi's formula, the rule for differentiating a determinant, gives:
,
or one could transform to a coordinate system where is diagonal and then apply the product rule to differentiate the product of factors on the main diagonal. Using this we get
In the last equality we used the fact that
which follows from the rule for differentiating the inverse of a matrix
.
Thus we conclude that
Equation of motion
Now that we have all the necessary variations at our disposal, we can insert () and () into the equation of motion () for the metric field to obtain
which is the Einstein field equations, and
has been chosen such that the non-relativistic limit yields the usual form of Newton's gravity law, where is the gravitational constant (see here for details).
Cosmological constant
When a cosmological constant Λ is included in the Lagrangian, the action:
Taking variations with respect to the inverse metric:
Using the action principle:
Combining this expression with the results obtained before:
We can obtain:
With , the expression becomes the field equations with a cosmological constant:
See also
Belinfante–Rosenfeld tensor
Brans–Dicke theory (in which the constant k is replaced by a scalar field).
Einstein–Cartan theory
f(R) gravity (in which the Ricci scalar is replaced by a function of the Ricci curvature)
Gibbons–Hawking–York boundary term
Kaluza–Klein theory
Komar superpotential
Palatini action
Teleparallelism
Tetradic Palatini action
Variational methods in general relativity
Vermeil's theorem
Notes
Bibliography
Hilbert, D. (1915) Die Grundlagen der Physik (German original for free) (English translation for $25), Konigl. Gesell. d. Wiss. Göttingen, Nachr. Math.-Phys. Kl. 395–407
Christopher M. Hirata Lecture 33: Lagrangian formulation of GR (27 April 2012).
Variational formalism of general relativity
General relativity
Albert Einstein
Gravity
David Hilbert | Einstein–Hilbert action | Physics | 1,179 |
13,129,573 | https://en.wikipedia.org/wiki/MathWorks%20Math%20Modeling%20Challenge | MathWorks Math Modeling Challenge (M3 Challenge) is a mathematical modeling competition open to high schools in the U.S. (including US territories and DoDEA schools) and schools with sixth form students (age 16-19) in England and Wales. It is sponsored by MathWorks (a developer of mathematical computing software) based in Boston and organized by the Society for Industrial and Applied Mathematics (SIAM) based in Philadelphia.
M3 Challenge awards $100,000 in scholarship prizes each year to the top teams. Additional incentives are expenses-paid trips for top performing teams to the final event in New York City each April, and media recognition that the winning teams receive. Some examples of recognition: the winning paper from 2008 was published in the College Mathematics Journal. A representative from High Tech's team appeared on FOX Business Channel, 2010 winners were interviewed by Pimm Fox of Bloomberg radio, presented its findings at Lockheed Martin's Data Capture Center, and met with U.S. Census Bureau Director Dr. Robert Groves. Many Champion teams have had their solution papers and research published in SIAM's undergraduate publication, SIAM Undergraduate Research Online (SIURO). The 2011 and 2012 winners were interviewed by Pimm Fox of Bloomberg radio, and the 2014 winners were interviewed by both Pimm Fox and Carol Massar on Bloomberg radio. Many local and regional TV and radio stations interview top teams; and in 2021 both NPR and the BBC interviewed top teams about their work and the problem topic of defeating the digital divide and making internet accessible to all.
MathWorks took over sponsorship of the competition, formerly known as the Moody's Mega Math (M³) Challenge, from Moody's Foundation in 2017.
Registration process
Registration is open to high school juniors and seniors or sixth form students (age 16-19) in eligible areas as well as to homeschooled and cyber schooled students. Teams consist of three to five students and one coach, who must be a teacher at their school. Each school can have a maximum of two teams. There is no cost to register or participate in the Challenge.
Eligibility
High schools in the U.S. (including US territories and DoDEA schools) are eligible. Schools with sixth form students (age 16-19) in England and Wales are eligible.
Challenge weekend
The M3 Challenge is held annually on a Friday, Saturday, Sunday, and Monday in late February or early March. Students choose which day and what continuous span of 14 hours that they wish to work over Challenge weekend. All teams will work in, or convert their local time to, Eastern Standard Time. Once the problem is downloaded, the clock starts and it cannot be paused; students should download the problem with at least fourteen hours before the firm end of Challenge weekend to have use of the full fourteen hours allowed. They can work from any location they choose. Teacher-coaches are not required to be physically with or near the team during Challenge weekend. Team members may not discuss any aspect of the problem with, nor seek help from via any means or method, the coach or anyone other than their teammates over Challenge weekend.
The problem
Professional Ph.D.-level applied mathematicians devise and write the Challenge problem. Students have no knowledge of the problem before they download it on Challenge weekend. To solve the problem, they are allowed to use any inanimate and publicly available sources. They cannot have any outside help from anyone, including their teacher-coach. A helpful discussion forum leading up to the problem release, a practice problem with live text chat discussion, can be found here. Below are previous problems:
2006 Problem – Solving the Social Security Stalemate
2007 Problem – Beat the Street!
2008 Problem – Energy Independence Meets the Law of Unintended Consequences
2009 Problem – $787 Billion: Will the Stimulus Act Stimulate the U.S. Economy
2010 Problem – Making Sense of the 2010 Census
2011 Problem – Colorado River Water: Good to the Last Acre-Foot
2012 Problem – All Aboard: Can High Speed Rail Get Back on Track?
2013 Problem – Waste Not, Want Not: Putting Recyclables in Their Place
2014 Problem – Lunch Crunch: Can Nutritious Be Affordable and Delicious?
2015 Problem – Stem Sells: What is Higher Education Really Worth?
2016 Problem – Share and (Car) Share Alike – Modeling New Approaches to Mobility
2017 Problem – From Sea to Shining Sea: Looking Ahead with the National Park Service
2018 Problem – Better Ate Than Never: Reducing Food Waste
2019 Problem – One is Too Many and A Thousand Not Enough: Substance Use and Abuse
2020 Problem – Keep On Trucking: U.S. Big Rigs Turnover From Diesel to Electric
2021 Problem – Defeating the Digital Divide: Internet Costs, Needs, and Optimal Planning
2022 Problem – Remote Work: Fad or Future
2023 Problem – Ride Like the Wind Without Getting Winded: The growth of E-Bike use
Judging
Ph.D.-level applied mathematicians judge the contest in three phases. In triage, each paper is read through at least two times, and as many as five times, before being eliminated or passed on to the second round. The triage round of judging eliminates two-thirds or more of the submitted papers. In the second round of judging, papers are read up to an additional twelve times each, and the top papers emerge. The top six papers overall become Finalists and go on to the final event and presentation round of judging. The M3 Challenge Technical Computing Scholarship Award, begun in 2018, honors teams for an outstanding use of computer programming (other than spreadsheets); these awardees also are invited to and present at the final event. Judging is blind, with teams known only by a unique team ID number, until the validation and presentation round during the final event. Finalist and Technical Computing Awardee teams present their papers live to a panel of judges during the final event. Following the presentations, judges rank the teams and a formal award ceremony takes place.
Prizes
All students who submit a viable solution paper receive certificates of participation, which are mailed to their teacher-coach. Coaches also receive certificates. Judges award additional semi-finalist and honorable mention team awards in amounts of $1,500 and $1,000 per team, respectively. Semi-finalist prizes are awarded to teams whose papers were highly ranked and underwent in-depth, specific discussion by judges.
Honorable mention prizes are awarded to teams whose papers are judged to be worthy of recognition for their superior efforts.
The top six teams' schools are awarded trophies. Scholarship prizes for the top six finalist teams and the technical computing awardees are as follows (GBP equivalent for U.K. winning teams):
M3 Challenge Champions (Summa Cum Laude Team Prize) $20,000
M3 Challenge Runner Up (Magna Cum Laude Team Prize) $15,000
M3 Challenge Third Place (Cum Laude Team Prize) $10,000
M3 Challenge Finalist (Meritorious Team Prize) $5,000 (3 teams)
M3 Challenge Technical Computing Winner $3000
M3 Challenge Technical Computing Runner Up $2000
M3 Challenge Technical Computing Third Place $1000
Awards and recognition for the M3 Challenge
SIAM received an Award of Excellence in the first round of the 2009 Associations Advance America (AAA) Awards program for its role in organizing and administering Moody's Mega Math Challenge
Moody's Corporation received a 2008 Excellence Award from the Committee Encouraging Corporate Philanthropy (CECP)for the company's sophisticated giving program which encourages students to develop a passion for mathematics, economics and finance, and specifically citing Moody's Mega Math Challenge which aims to excite students about employing mathematics to solve real world problems.
The M3 Challenge has received placement on the National Association of Secondary School Principals' National Advisory List of Student Contests & Activities since 2010.
Resources
Here are some helpful resources:
Math Modeling handbooks, one for getting started and one for adding computing
A "how-to" video: About M3 Challenge
Guidelines for Assessment and Instruction in Mathematical Modeling Education (GAIMME)
Sample problems
What is Math Modeling video series
Learn Technical Computing
References
External links
That Was Easy: Social Security Problem Solved
West Windsor-Plainsboro North team in top five in Moody's Math Challenge
Winning "Moody's Mega Math Challenge" Paper Published in CMJ
Mathematics competitions
Society for Industrial and Applied Mathematics | MathWorks Math Modeling Challenge | Engineering | 1,659 |
4,455,943 | https://en.wikipedia.org/wiki/Incremental%20backup | An incremental backup is one in which successive copies of the data contain only the portion that has changed since the preceding backup copy was made. When a full recovery is needed, the restoration process would need the last full backup plus all the incremental backups until the point of restoration. Incremental backups are often desirable as they reduce storage space usage, and are quicker to perform than differential backups.
Variants
Incremental
The most basic form of incremental backup consists of identifying, recording and thus, preserving only those files that have changed since the last backup. Since changes are typically low, incremental backups are much smaller and quicker than full backups. For instance, following a full backup on Friday, a Monday backup will contain only those files that changed since Friday. A Tuesday backup contains only those files that changed since Monday, and so on. A full restoration of data will naturally be slower, since all increments must be restored. Should any one of the copies created fail, including the first (full), restoration will be incomplete.
A Unix example would be: rsync -e ssh -va --link-dest=$dst/hourly.0 $remoteserver:$remotepath $dst/hourly.1
The use of rsync's option is what makes this command an example of incremental backup.
Multilevel incremental
A more sophisticated incremental backup scheme involves multiple numbered backup levels. A full backup is level 0. A level n backup will back up everything that has changed since the most recent level n-1 backup. Suppose for instance that a level 0 backup was taken on a Sunday. A level 1 backup taken on Monday would include only changes made since Sunday. A level 2 backup taken on Tuesday would include only changes made since Monday. A level 3 backup taken on Wednesday would include only changes made since Tuesday. If a level 2 backup was taken on Thursday, it would include all changes made since Monday because Monday was the most recent level n-1 backup.
Reverse incremental
An incremental backup of the changes made between two instances of a mirror can be forward or reverse.
If the oldest version of the mirror is treated as the base and the newest version as the revised version, the incremental produced is a forward incremental.
If the newest version of the mirror is treated as the base and the oldest version as the revised / changed version, the incremental produced is a reverse incremental.
In making backups using reverse incremental backups, each time a reverse incremental backup is taken, it is applied (in reverse) to the previous full (synthetic) backup, thus the current full (synthetic) backup is always a backup of the most recent state of the system. This is in contrast to forward incremental backups where the current full backup is a backup of the oldest version of the system, and to get a backup of the most recent state of the system, all of the forward incremental backups have to be applied to that oldest version successively.
By applying a reverse incremental to a mirror, the result will be a previous version of the mirror. This gives a means to revert to any previous version of the mirror.
In other words, after the initial full backup, each successive incremental backup applies the changes to the previous full, creating a new synthetic full backup every time, while maintaining the ability to revert to previous versions.
The main advantage of this type of backup is a more efficient recovery process, since the most recent version of the data (which is the most frequently restored version) is a (synthetic) full backup, and no incrementals need to be applied to it during its restoration. Reverse incremental backup works for both tapes and disks, but in practice tends to work better with disks.
Companies using the reverse incremental backup method include Intronis and Zetta.net.
Incremental forever
This style is similar to the synthetic backup concept. After an initial full backup, only the incremental backups are sent to a centralized backup system. This server keeps track of all the increments and sends the proper data back to the client during restores. This can be implemented by sending each incremental directly to tape as it is taken and then refactoring the tapes as necessary. If enough disk space is available, an online mirror can be maintained along with previous incremental changes so that the current or older versions of the systems being backed up can be restored. This is a suitable method in the case of banking systems.
In modern cloud architectures, or disk to disk backup scenarios, this is much simpler. Data is broken into chunks and placed on a cloud storage system. Metadata about the chunks is stored in a persistent system, which allows the system to assemble a point in time backup from these chunks at restore time. There is no need to refactor tape.
Block-level incremental
This method backs up only the blocks within the file that changed. This requires a higher level of integration between the sender and receiver.
Byte-level incremental
These backup technologies are similar to the "block-level incremental" backup method; however, the byte (or binary) incremental backup method is based on a binary variation of the files compared to the previous backup: while the block-based technologies work with heavy changing units (blocks of 8K, 4K or 1K), the byte-based technologies work with the minimum unit, saving space when reflecting a change on a file. Another important difference is that they work independently on the file system. At the moment, these are the technologies that achieve the highest relative compression of the data, turning into a great advantage for the security copies carried out through the Internet.
Other backup types
Synthetic full backup
A synthetic backup is an alternative method of creating full backups. Instead of reading and backing up data directly from the disk, it will synthesize the data from the previous full backup (either a regular full backup for the first backup, or the previous synthetic full backup) and the periodic incremental backups. As only the incremental backups read data from the disk, these are the only files that need to be transferred during offsite replication. This greatly reduces the bandwidth needed for offsite replication. Synthetic backup does not always work with the same efficiency. The rate of data uploaded from the target machine to data, synchronized on the storage, varies depending on the disk fragmentation.
Differential
A differential backup is a cumulative backup of all changes made since the last full or normal backup, i.e., the differences since the last full backup. The advantage to this is the quicker recovery time, requiring only a full backup and the last differential backup to restore the system. The disadvantage is that for each day elapsed since the last full backup, more data needs to be backed up, especially if a significant proportion of the data has changed.
Forward incremental-forever
A forward incremental-forever backup allows the synthetic operation to create a new full backup, which is limited to the size of the incremental file, instead of the complete size of a full backup file as it would happen in a “forward mode with synthetic fulls”. The overall consumed I/O is the same as the reversed incremental, but during the duration of the backup activity only 1 write I/O is used and the snapshot of the VM is opened for less time than the reversed incremental; the remaining 2 I/O are used to update the full backup file.
See also
Backup rotation scheme
Continuous data protection
Delta encoding
Dump (Unix) - UNIX utility for multilevel incremental file system backups.
Incremental computing
rsync - File synchronization algorithm and protocol.
References
Further reading
Data synchronization
Incremental computing
Backup | Incremental backup | Engineering | 1,620 |
63,004,431 | https://en.wikipedia.org/wiki/Dichapetalins | Dichapetalins are a small class of triterpenoid compounds found primarily in the Dichapetalaceae family but also reportedly in Phyllanthus (Euphorbiaceae). They are structural derivatives of dammarene characterized by a C6C2 unit connected to a dammarene or a 13,30-cyclodammarane skeleton with variable C-17 side chains containing actone, spirolactone, lactol, acetal, or furan moieties. They have been found to display cytotoxicity against several cancer cell lines.
References
Triterpenes | Dichapetalins | Chemistry | 130 |
22,217,265 | https://en.wikipedia.org/wiki/Nucleic%20acid%20structure%20determination | Experimental approaches of determining the structure of nucleic acids, such as RNA and DNA, can be largely classified into biophysical and biochemical methods. Biophysical methods use the fundamental physical properties of molecules for structure determination, including X-ray crystallography, NMR and cryo-EM. Biochemical methods exploit the chemical properties of nucleic acids using specific reagents and conditions to assay the structure of nucleic acids. Such methods may involve chemical probing with specific reagents, or rely on native or analogue chemistry. Different experimental approaches have unique merits and are suitable for different experimental purposes.
Biophysical methods
X-ray crystallography
X-ray crystallography is not common for nucleic acids alone, since neither DNA nor RNA readily form crystals. This is due to the greater degree of intrinsic disorder and dynamism in nucleic acid structures and the negatively charged (deoxy)ribose-phosphate backbones, which repel each other in close proximity. Therefore, crystallized nucleic acids tend to be complexed with a protein of interest to provide structural order and neutralize the negative charge.
Nuclear magnetic resonance spectroscopy (NMR)
Nucleic acid NMR is the use of NMR spectroscopy to obtain information about the structure and dynamics of nucleic acid molecules, such as DNA or RNA. As of 2003, nearly half of all known RNA structures had been determined by NMR spectroscopy.
Nucleic acid NMR uses similar techniques as protein NMR, but has several differences. Nucleic acids have a smaller percentage of hydrogen atoms, which are the atoms usually observed in NMR, and because nucleic acid double helices are stiff and roughly linear, they do not fold back on themselves to give "long-range" correlations. The types of NMR usually done with nucleic acids are 1H or proton NMR, 13C NMR, 15N NMR, and 31P NMR. Two-dimensional NMR methods are almost always used, such as correlation spectroscopy (COSY) and total coherence transfer spectroscopy (TOCSY) to detect through-bond nuclear couplings, and nuclear Overhauser effect spectroscopy (NOESY) to detect couplings between nuclei that are close to each other in space.
Parameters taken from the spectrum, mainly NOESY cross-peaks and coupling constants, can be used to determine local structural features such as glycosidic bond angles, dihedral angles (using the Karplus equation), and sugar pucker conformations. For large-scale structure, these local parameters must be supplemented with other structural assumptions or models, because errors add up as the double helix is traversed, and unlike with proteins, the double helix does not have a compact interior and does not fold back upon itself. NMR is also useful for investigating nonstandard geometries such as bent helices, non-Watson–Crick basepairing, and coaxial stacking. It has been especially useful in probing the structure of natural RNA oligonucleotides, which tend to adopt complex conformations such as stem-loops and pseudoknots. NMR is also useful for probing the binding of nucleic acid molecules to other molecules, such as proteins or drugs, by seeing which resonances are shifted upon binding of the other molecule.
Cryogenic electron microscopy (cryo-EM)
Cryogenic electron microscopy (cryo-EM) is a technique that uses an electron beam to image samples that have been cryogenically preserved in an aqueous solution. Liquid samples are pipetted on small metallic grids and plunged into a liquid ethane/propane solution which is kept extremely cold by a liquid nitrogen bath. Upon this freezing process, water molecules in the sample do not have enough time to form hexagonal lattices as found in ice, and therefore the sample is preserved in a glassy water-like state (also referred to as a vitrified ice), making these samples easier to image using the electron beam. An advantage of cryo-EM over x-ray crystallography is that the samples are preserved in their aqueous solution state and not perturbed by forming a crystal of the sample. One disadvantage, is that it is difficult to resolve nucleic acid or protein structures that are smaller than ~75 kilodaltons, partly due to the difficulty of having enough contrast to locate particles in this vitrified aqueous solution. Another disadvantage is that to attain atomic-level structure information about a sample requires taking many images (often referred to as electron micrographs) and averaging over those images in a process called single-particle reconstruction. This is a computationally intensive process.
Cryo-EM is a newer, less perturbative version of transmission electron microscopy (TEM). It is less perturbative because the sample is not dried onto a surface, this drying process is often done in negative-stain TEM, and because Cryo-EM does not require contrast agent like heavy metal salts (e.g. uranyl acetate or phoshotungstic acid) which also may affect the structure of the biomolecule. Transmission electron microscopy, as a technique, utilizes the fact that samples interact with a beam of electrons and only parts of the sample that do not interact with the electron beam are allowed to 'transmit' onto the electron detection system. TEM, in general, has been a useful technique in determining nucleic acid structure since the 1960s. While double-stranded DNA (dsDNA) structure may not traditionally be considered structure, in the typical sense of alternating segments of single- and double-stranded regions, in reality, dsDNA is not simply a perfectly ordered double helix at every location of its length due to thermal fluctuations in the DNA and alternative structures that can form like g-quadruplexes. CryoEM of nucleic acid has been done on ribosomes, viral RNA, and single-stranded RNA structures within viruses. These studies have resolved structural features at different resolutions from the nucleobase level (2-3 angstroms) up to tertiary structure motifs (greater than a nanometer).
Chemical probing
RNA chemical probing uses chemicals that react with RNAs. Importantly, their reactivity depends on local RNA structure e.g. base-pairing or accessibility. Differences in reactivity can therefore serve as a footprint of structure along the sequence. Different reagents react at different positions on the RNA structure, and have different spectra of reactivity. Recent advances allow the simultaneous study of the structure of many RNAs (transcriptome-wide probing) and the direct assay of RNA molecules in their cellular environment (in-cell probing).
Structured RNA is first reacted with the probing reagents for a given incubation time. These reagents would form a covalent adduct on the RNA at the site of reaction. When the RNA is reverse transcribed using a reverse transcriptase into a DNA copy, the DNA generated is truncated at the positions of reaction because the enzyme is blocked by the adducts. The collection of DNA molecules of various truncated lengths therefore informs the frequency of reaction at every base position, which reflects the structure profile along the RNA. This is traditionally assayed by running the DNA on a gel, and the intensity of bands inform the frequency of observing a truncation at each position. Recent approaches use high-throughput sequencing to achieve the same purpose with greater throughput and sensitivity.
The reactivity profile can be used to study the degree of structure at particular positions for specific hypotheses, or used in conjunction with computational algorithms to produce a complete experimentally supported structure model.
Depending on the chemical reagent used, some reagents, e.g. hydroxyl radicals, would cleave the RNA molecule instead. The result in the truncated DNA is the same. Some reagents, e.g. DMS, sometimes do not block the reverse transcriptase, but trigger a mistake at the site in the DNA copy instead. These can be detected when using high-throughput sequencing methods, and is sometimes employed for improved results of probing as mutational profiling (MaP).
Positions on the RNA can be protected from the reagents not only by local structure but also by a binding protein over that position. This has led some work to use chemical probing to also assay protein-binding.
Hydroxyl radical probing
As hydroxyl radicals are short-lived in solution, they need to be generated upon experiment. This can be done using H2O2, ascorbic acid, and Fe(II)-EDTA complex. These reagents form a system that generates hydroxyl radicals through Fenton chemistry. The hydroxyl radicals can then react with the nucleic acid molecules. Hydroxyl radicals attack the ribose/deoxyribose ring and this results in breaking of the sugar-phosphate backbone. Sites under protection from binding proteins or RNA tertiary structure would be cleaved by hydroxyl radical at a lower rate. These positions would therefore show up as absence of bands on the gel, or low signal through sequencing.
DMS
Dimethyl sulfate, known as DMS, is a chemical that can be used to modify nucleic acids in order to determine secondary structure. Reaction with DMS adds a methyl adduct at the site, known as methylation. In particular, DMS methylates N1 of adenine (A) and N3 of cytosine (C), both located at the site of natural hydrogen bonds upon base-pairing. Therefore, modification can only occur at A and C nucleobases that are single-stranded, base paired at the end of a helix, or in a base pair at or next to a GU wobble pair, the latter two being positions where the base-pairing can occasionally open up. Moreover, since modified sites cannot be base-paired, modification sites can be detected by RT-PCR, where the reverse transcriptase falls off at methylated bases and produces different truncated cDNAs. These truncated cDNAs can be identified through gel electrophoresis or high-throughput sequencing.
Improving upon truncation-based methods, DMS mutational profiling with sequencing (DMS-MaPseq) can detect multiple DMS modifications in a single RNA molecule, which enables one to obtain more information per read (for a read of 150 nt, typically two to three mutation sites, rather than zero to one truncation sites), determine structures of low-abundance RNAs, and identify subpopulations of RNAs with alternative secondary structures. DMS-MaPseq uses a thermostable group II intron reverse transcriptase (TGIRT) that creates a mutation (rather than a truncation) in the cDNA when it encounters a base methylated by DMS, but otherwise it reverse transcribes with high fidelity. Sequencing the resulting cDNA identifies which bases were mutated during reverse transcription; these bases cannot have been base-paired in the original RNA.
DMS modification can also be used for DNA, for example in footprinting DNA-protein interactions.
SHAPE
Selective 2′-hydroxyl acylation analyzed by primer extension, or SHAPE, takes advantage of reagents that preferentially modify the backbone of RNA in structurally flexible regions. Reagents such as N-methylisatoic anhydride (NMIA) and 1-methyl-7-nitroisatoic anhydride (1M7) react with the 2'-hydroxyl group to form adducts on the 2'-hydroxyl of the RNA backbone. Compared to the chemicals used in other RNA probing techniques, these reagents have the advantage of being largely unbiased to base identity, while remaining very sensitive to conformational dynamics. Nucleotides which are constrained (usually by base-pairing) show less adduct formation than nucleotides which are unpaired. Adduct formation is quantified for each nucleotide in a given RNA by extension of a complementary DNA primer with reverse transcriptase and comparison of the resulting fragments with those from an unmodified control. SHAPE therefore reports on RNA structure at the individual nucleotide level. This data can be used as input to generate highly accurate secondary structure models. SHAPE has been used to analyze diverse RNA structures, including that of an entire HIV-1 genome. The best approach is to use a combination of chemical probing reagents and experimental data. In SHAPE-Seq SHAPE is extended by bar-code based multiplexing combined with RNA-Seq and can be performed in a high-throughput fashion.
Carbodiimides
The carbodiimide moiety can also form covalent adducts at exposed nucleobases, which are uracil, and to a smaller extent guanine, upon nucleophilic attack by a deprotonated N. They react primarily with N3 of uracil and N1 of guanine modifying two sites responsible for hydrogen bonding on the bases.
1-cyclohexyl-(2-morpholinoethyl)carbodiimide metho-p-toluene sulfonate, also known as CMCT or CMC, is the most commonly used carbodiimide for RNA structure probing. Similar to DMS, it can be detected by reverse transcription followed by gel electrophoresis or high-throughput sequencing. As it is reactive towards G and U, it can be used to complement the data from DMS probing experiments, which inform A and C.
1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, also known as EDC, is a water-soluble carbodiimide that exhibits similar reactivity as CMC, and is also used for the chemical probing of RNA structure. EDC is able to permeate into cells and is thus used for direct in-cell probing of RNA in their native environments.
Kethoxal, glyoxal and derivatives
Some 1,2-dicarbonyl compounds are able to react with single-stranded guanine (G) at N1 and N2, forming a five-membered ring adduct at the Watson-Crick face.
1,1-Dihydroxy-3-ethoxy-2-butanone, also known as kethoxal, has a structure related to 1,2-dicarbonyls, and was the first in this category used extensively for the chemical probing of RNA. Kethoxal causes the modification of guanine, specifically altering the N1 and the exocyclic amino group (N2) simultaneously by covalent interaction.
Glyoxal, methylglyoxal, and phenylglyoxal, which all carry the key 1,2-dicarbonyl moiety, all react with free guanines similar to kethoxal, and can be used to probe unpaired guanine bases in structured RNA. Due to their chemical properties, these reagents can permeate readily into cells and can therefore be used to assay RNAs in their native cellular environments.
LASER or NAz Probing
Light-Activated Structural Examination of RNA (LASER) probing utilizes UV light to activate nicotinoyl azide (NAz), generating highly reactive nitrenium cation in water, which reacts with solvent accessible guanosine and adenosine of RNA at C-8 position through a barrierless Friedel-Crafts reaction. LASER probing targets both single-stranded and double-stranded residues as long as they are solvent accessible. Because hydroxyl radical probing requires synchrotron radiation to measure solvent accessibility of RNA in vivo, it is hard to apply hydroxyl radical probing to footprint RNA in cells for many laboratories. In contrast, LASER probing utilizes a hand-held UV lamp (20 W) for excitation, it is much easier to apply LASER probing for in vivo studying RNA solvent accessibility. This chemical probing method is light-controllable, and probes solvent accessibility of nucleobase, which has been shown to footprint RNA binding proteins inside cells.
In-line probing
In-line probing does not involve treatment with any type of chemical or reagent to modify RNA structures. This type of probing assay uses the structure dependent cleavage of RNA; single stranded regions are more flexible and unstable and will degrade over time. The process of in-line probing is often used to determine changes in structure due to ligand binding. Binding of a ligand can result in different cleavage patterns. The process of in-line probing involves incubation of structural or functional RNAs over a long period of time. This period can be several days, but varies in each experiment. The incubated products are then run on a gel to visualize the bands. This experiment is often done using two different conditions: 1) with ligand and 2) in the absence of ligand. Cleavage results in shorter band lengths and is indicative of areas that are not basepaired, as basepaired regions tend to be less sensitive to spontaneous cleavage. In-line probing is a functional assay that can be used to determine structural changes in RNA in response to ligand binding. It can directly show the change in flexibility and binding of regions of RNA in response to a ligand, as well as compare that response to analogous ligands. This assay is commonly used in dynamic studies, specifically when examining riboswitches.
Nucleotide analog interference mapping (NAIM)
Nucleotide analog interference mapping (NAIM) is the process of using nucleotide analogs, molecules that are similar in some ways to nucleotides but lack function, to determine the importance of a functional group at each location of an RNA molecule. The process of NAIM is to insert a single nucleotide analog into a unique site. This can be done by transcribing a short RNA using T7 RNA polymerase, then synthesizing a short oligonucleotide containing the analog in a specific position, then ligating them together on the DNA template using a ligase. The nucleotide analogs are tagged with a phosphorothioate, the active members of the RNA population are then distinguished from the inactive members, the inactive members then have the phosphorothioate tag removed and the analog sites are identified using gel electrophoresis and autoradiography. This indicates a functionally important nucleotide, as cleavage of the phosphorothioate by iodine results in an RNA that is cleaved at the site of the nucleotide analog insert. By running these truncated RNA molecules on a gel, the nucleotide of interest can be identified against a sequencing experiment Site directed incorporation results indicate positions of importance where when running on a gel, functional RNAs that have the analog incorporated at that position will have a band present, but if the analog results in non-functionality, when the functional RNA molecules are run on a gel there will be no band corresponding to that position on the gel. This process can be used to evaluate an entire area, where analogs are placed in site specific locations, differing by a single nucleotide, then when functional RNAs are isolated and run on a gel, all areas where bands are produced indicate non-essential nucleotides, but areas where bands are absent from the functional RNA indicate that inserting a nucleotide analog in that position caused the RNA molecule to become non-functional
References
RNA
Molecular biology techniques | Nucleic acid structure determination | Chemistry,Biology | 4,046 |
25,665,948 | https://en.wikipedia.org/wiki/C15H20O3 | {{DISPLAYTITLE:C15H20O3}}
The molecular formula C15H20O3 (molar mass: 248.32 g/mol, exact mass: 248.1412 u) may refer to:
Abscisic aldehyde
Amiloxate
Parthenolide
Periplanone B
Molecular formulas | C15H20O3 | Physics,Chemistry | 72 |
72,376,123 | https://en.wikipedia.org/wiki/Mentha%20%C3%97%20villosa | Mentha × villosa (syn: Mentha alopecuroides, Mentha nemorosa, Mentha villosa var. alopecuroides) also known as hairy mint or mojito mint is a hybrid species of mint, a cross between Mentha spicata and Mentha suaveolens.
This species is native to temperate and warm temperate regions of Europe and occurs in meadows, pastures, and ruderal locations. However, it is cultivated in many other countries throughout the world.
In Cuba and the Philippines, this species is known as yerba buena or hierbabuena. In Cuba, it is a core ingredient in the mojito cocktail, though other mints such as spearmint are used where mojito mint is not available. In the Philippines, this species has a long history of medicinal use and is one of 10 medicinal plant species that the Philippine government has endorsed as effective.
Description
Mentha × villosa is a herbaceous, rhizomatous, perennial plant that grows to be tall, with smooth stems, square in cross section. The rhizomes are wide-spreading and fleshy, and bear fibrous roots.
Cultivation
Historically, this species has been included in European medicinal and aromatic plant gardens, though its cultivation in Europe is in decline. However, the mojito mint variety from Cuba has become increasingly popular in the United States and elsewhere as a culinary garden plant for making mojitos and other culinary uses. It is a perennial and grows primarily in the temperate biome.
References
Antiemetics
Herbs
villosa
Hybrid plants
Plants described in 1778 | Mentha × villosa | Biology | 337 |
730,907 | https://en.wikipedia.org/wiki/Focal%20cortical%20dysplasia | Focal cortical dysplasia (FCD) is a congenital abnormality of brain development where the neurons in an area of the brain failed to migrate in the proper formation in utero. Focal means that it is limited to a focal zone in any lobe. Focal cortical dysplasia is a common cause of intractable epilepsy in children and is a frequent cause of epilepsy in adults. There are three types of FCD with subtypes, including type 1a, 1b, 1c, 2a, 2b, 3a, 3b, 3c, and 3d, each with distinct histopathological features. All forms of focal cortical dysplasia lead to disorganization of the normal structure of the cerebral cortex:
Type 1 FCD exhibits subtle alterations in cortical lamination.
Type 2a FCD exhibits neurons that are larger than normal that are called dysmorphic neurons (DN). FCD type 2b exhibits complete loss of laminar structure, and the presence of DN and enlarged cells are called balloon cells (BC) for their large elliptical cell body shape, laterally displaced nucleus, and lack of dendrites or axons. The developmental origin of balloon cells is currently believed to be derived from neuronal or glial progenitor cells. Balloon cells are similar in structure to giant cells in the disorder tuberous sclerosis complex.
Type 3 FCDs are cortical disorganisation associated with other lesions such as hippocampal sclerosis (type 3a), long-term epilepsy-associated tumors (3b), vascular malformations (3c) or scar/hypoxic damages (3d).
Recent studies have demonstrated that FCD types 2a and 2b result from somatic mutations in genes that encode components of the mammalian target of rapamycin (mTOR) pathway. Causative gene mutations for types 1 and 3 have not been identified. The mTOR pathway regulates a number of functions in the brain including establishment of cell size, cell motility, and differentiation. Gene mutations associated with FCD2a and FCD 2b include MTOR, PI3KCA, AKT3, and DEPDC5. Mutations in these genes lead to enhanced mTOR pathway signaling at critical periods in brain development. Some recent evidence may suggest a role for in utero infection with certain viruses such as cytomegalovirus and human papilloma virus.
Seizures in FCD are likely caused by abnormal circuitry induced by the presence of DNs and BCs. These abnormal cell types generate abnormal electrical signals which spread out to affect other parts of the cerebral cortex. Medication is used to treat the seizures that may arise due to cortical dysplasia. Epilepsy surgery to remove areas of FCD is a viable treatment option for appropriate candidates.
Treatment
No specific treatment is required for cortical dysplasia, and all treatment is aimed at the resulting symptoms (typically seizures). When a cortical dysplasia is a cause of epilepsy, then seizure medications (anticonvulsants) are a first line treatment. If anticonvulsants fail to control seizure activity, neurosurgery may be an option to remove or disconnect the abnormal cells from the rest of the brain (depending on where the cortical dysplasia is located and the safety of the surgery relative to continued seizures). Neurosurgery can range from removing an entire hemisphere (hemispherectomy), a small lesionectomy, or multiple transections to try to disconnect the abnormal tissue from the rest of the brain (multiple subpial transsections). Physical therapy should be considered for infants and children with muscle weakness. Educational therapy is often prescribed for those with developmental delays, but there is no complete treatment for the delays.
See also
Gray matter heterotopia
References
External links
Histopathology | Focal cortical dysplasia | Chemistry | 824 |
9,272,721 | https://en.wikipedia.org/wiki/Kinematic%20diagram | In mechanical engineering, a kinematic diagram or kinematic scheme (also called a joint map or skeleton diagram) illustrates the connectivity of links and joints of a mechanism or machine rather than the dimensions or shape of the parts. Often links are presented as geometric objects, such as lines, triangles or squares, that support schematic versions of the joints of the mechanism or machine.
For example, the figures show the kinematic diagrams (i) of the slider-crank that forms a piston and crank-shaft in an engine, and (ii) of the first three joints for a PUMA manipulator.
|- style="text-align:center;"
| ||
|- style="text-align:center;"
| PUMA robot || and its kinematic diagram
Linkage graph
A kinematic diagram can be formulated as a graph by representing the joints of the mechanism as vertices and the links as edges of the graph. This version of the kinematic diagram has proven effective in enumerating kinematic structures in the process of machine design.
An important consideration in this design process is the degree of freedom of the system of links and joints, which is determined using the Chebychev–Grübler–Kutzbach criterion.
Elements of machines
Elements of kinematics diagrams include the frame, which is the frame of reference for all the moving components, as well as links (kinematic pairs), and joints. Primary Joints include pins, sliders and other elements that allow pure rotation or pure linear motion. Higher order joints also exist that allow a combination of rotation or linear motion. Kinematic diagrams also include points of interest, and other important components.
See also
Free body diagram
Kinematic synthesis
Left-hand–right-hand activity chart
References
Mechanisms (engineering)
Diagrams
Classical mechanics | Kinematic diagram | Physics,Engineering | 378 |
2,666,536 | https://en.wikipedia.org/wiki/Bone%20meal | Bone meal (or bonemeal) is a mixture of finely and coarsely ground animal bones and slaughter-house waste products. It is used as a dietary supplement to supply calcium and phosphorus to monogastric livestock in the form of hydroxyapatite. As a slow-release organic fertilizer, it supplies phosphorus, calcium, and a small amount of nitrogen to plants.
Uses
Dietary supplement
Bone meal, along with a variety of other meals, especially meat meal, is used as a dietary/mineral supplement for livestock. The improper application of bone and meat meal products in animal nutrition can contribute to the spread of transmissible spongiform encephalopathy, commonly known in cattle as Mad Cow Disease. Proper heat control can reduce salmonella contaminants.
Bone meal was historically used as a human dietary calcium supplement. Research has shown that calcium and lead in their ionic forms (Ca2+, Pb2+) have similar atomic structures and so create a potential for accumulation of lead in bones. American actress Allison Hayes was poisoned in the 1970s with a calcium supplement made from horse bone containing high amounts of lead, which moved the EPA to develop more stringent importation rules.
Fertilizer
Bone meal provides phosphorus and calcium to plants, along with a largely inconsequential amount of nitrogen. The N-P-K rating of bone meal is typically 3–15–0 along with a calcium content of around 12% (18% CaO equiv.), although it can vary quite a bit depending on the source from 1–13–0 to 3–22–0.
As bone meal is water-insoluble, it needs to be broken down before the plant can absorb it, either by soil acidity or by microbial activity producing acids. According to the Colorado State University, it can only be broken down in acidic soil (pH < 7.0) and releases its nutrients over a span of 1 to 4 months.
History
The process was first suggested by Justus von Liebig (dissolving animal bones in sulphuric acid) around 1840 and first used in Britain by Rev James Robertson in Ellon, Aberdeenshire in 1841.
Before Liebig, the expansion of agriculture had depleted the soil of essential nutrients. In desperation, farmers collected the bones from major battlefields like the Battle of Waterloo and the Battle of Austerlitz to crush them and refertilize the soil.
In 19th-century Europe, large-scale production and international trade in bone meal was seen as essential for agricultural development.
See also
Blood meal
Bone crusher
Feather meal
Meat and bone meal
Organic hydroponic solutions
References
Soil improvers
Meal
Organic fertilizers
Animal products | Bone meal | Chemistry | 552 |
1,449,951 | https://en.wikipedia.org/wiki/Mist%20net | Mist nets are nets used to capture wild birds and bats. They are used by hunters and poachers to catch and kill animals, but also by ornithologists and chiropterologists for banding and other research projects. Mist nets are typically made of nylon or polyester mesh suspended between two poles, resembling a volleyball net. When properly deployed in the correct habitat, the nets are virtually invisible. Mist nets have shelves created by horizontally strung lines that create a loose, baggy pocket. When a bird or bat hits the net, it falls into this pocket, where it becomes tangled.
The mesh size of the netting varies according to the size of the species targeted for capture. Mesh sizes can be measured along one side of the edge of a single mesh square, or along the diagonal of that square. Measures given here are along the diagonal. Small passerines are typically captured with 16-30 mm mesh, while larger birds, like hawks and ducks, are captured using mesh sizes of ~127 mm. Net dimensions can vary widely depending on the proposed use. Net height for avian mist netting is typically 1.2 - 2.6 m. Net width may vary from 3 to 18 m, although longer nets may also be used. A dho-gazza is a type of mist net that can be used for larger birds, such as raptors. This net lacks shelves.
The purchase and use of mist nets requires permits, which vary according to a country or state's wildlife regulations. Mist net handling requires skill for optimal placement, avoiding entangling nets in vegetation, and proper storage. Bird and bat handling requires extensive training to avoid injury to the captured animals. Bat handling may be especially difficult since bats are captured at night and may bite. A 2011 research survey found mist netting to result in low rates of injury while providing high scientific value.
Usage of mist nets
Mist nets have been used by Japanese hunters for nearly 300 years to capture birds. They were first introduced into use for ornithology in the United States of America by Oliver L. Austin in 1947.
Mist netting is a popular and important tool for monitoring species diversity, relative abundance, population size, and demography. There are two ways in which mist nets are primarily utilized: target netting of specific species or individuals, and broadcast netting of all birds within a particular area. Targeted netting is typically used for scientific studies that examine a single species. Nets deployed in this manner often use a playback of a species' song or call, or a model of that species placed near the net to lure the targeted individuals into the net (e.g. ).
Because broadcast netting captures birds indiscriminately, this technique is better suited to examining the species that occur within a specific habitat. Bird banding stations throughout the United States use this method. Typically, such stations collect a set of standard measurements from each individual, including mass, wing chord, breeding status, body fat index, sex, age, and molt status.
Although setting up mist nets is time-consuming and requires certification, there are certain advantages compared to visual and aural monitoring techniques, such as sampling species that may be poorly detected in other ways. It also allows easy standardization, hands-on examination, and reduces misidentification of species. Because they allow scientists to examine species up close, mist nets are often used in mark-recapture studies over extended periods of time to detect trends in population indices.
Some uses of data collected using mist net sampling are:
Mark-recapture for population sampling
Humane capture and relocation of small birds or bats
Tagging and tracking
Testing health of bird or bat species and for ectoparasite studies
Examination of avian phenology in response to climatic and other variables
Examination of patterns of molt
Because there is still debate as to whether or not these techniques provide precise data, it is suggested that mist netting be used as a supplement to aural and visual methods of observation.
One of the main disadvantages of mist nets is that the numbers captured may only represent a small proportion of the true population size. Mist netting is a unique method in that it provides demographic estimates throughout all seasons, and offers valuable guides to relative abundance of certain species or birds and/or bats.
Example study
Mist nets can be important tools for collecting data to reveal critical ecological conditions in a
variety of situations. This summarized study, "Effects of forest fragmentation on Amazonian understory bird communities" by Richard O. Bierregaard and Thomas E. Lovejoy, used mist nets to analyze the effects of forest fragmentation on understory bird communities in terra firme forest of Central Amazon.
Data from intensive mist netting mark-recapture programs on understory birds from isolated forest reserves were compared to pre-isolation data from the same reserves to investigate changes related to isolation from continuous forest. Birds surveyed were from a variety of ecological guilds, including nectivores, insectivores, frugivores, obligatory army ant followers, forest edge specialists and flocking species. Periodic sampling by the mist netting capture program provided the quantitative basis for this project. Reserves of varied sizes (1 and 10 hectare) within the Biological Dynamics of Forest Fragments project site were sampled with transects of tethered mist nets once every three or four weeks. Capture rates from isolated reserves were compared to pre-isolation rates to measure changes in population size and/or avian activity due to isolation. Data was analyzed in the following ways: capture rates per net hour as a function of time since isolation, percent recapture as a function of time since isolation, abundance distribution of species against the species rank by abundance, percent individuals banded according to species and feeding strategy, and finally, capture rates per net hour in isolated reserves against capture rates per net hour in continuous forests. A summary of the results and discussion as stated by Bierregaard and Lovejoy is as follows:
...changes in the understory avian community in isolated patches. Following isolation, capture rates increase significantly as birds fleeing the felled forest entered new forest fragments. Movement to and from the reserve is limited as witnessed by an increase in recapture percentages following isolation. Species of birds that are obligate army ant followers disappeared at the time the surrounding habitat was removed from 1 and 10 ha areas. The complex mixed-species of insectivorous flocks typical of Amazonian forests deteriorated within 2 years of isolation of 1 and 10 ha forest fragments. Several species of mid-story insectivores changed their foraging behavior after isolation of small forest reserves.
These data were collected using mist nets. Data from mist netting efforts may be used to gain a greater understanding of ecological effects of factors impacting ecosystems, such human activities or environmental changes. This is just one example of the use of mist nets as a tool for ecological and biological sciences. Mist net data can also have ecosystem management implications.
Disadvantages
The use of mist nets has several disadvantages. Mist-netting is very time-consuming. Nets have to be set up without mistakes. An animal caught in a mist net becomes entangled, so the net must be checked often and the animal removed promptly. Disentangling an animal from a mist net can be difficult and must be done carefully by trained personnel. If an animal is heavily entangled, the mist net may need to be cut to avoid injuring the animal, damaging the material.
Mist nets will not capture birds in direct proportion to their presence in the area (Remsen and Good 1996) and can miss a species completely if it is active in a different strata of vegetation, such as high in the canopy. They can, however, provide an index to population size.
People using mist nets must be careful and well-trained, since the capture process can harm birds. One study found the average rate of injury for birds in mist nets is lower than any other method of studying vertebrates, between 0 and 0.59% while the average mortality rate is between 0 and 0.23%.
While rare, it has been suggested (without scientific studies) that larger birds may be more prone to leg injuries and internal bleeding. Smaller birds typically have problems with tangling issues and wing injuries. Factors that affect the injury and mortality rate are human error while handling the species, time of year caught, time of day caught, predators in the area, and size/material of the mist net.
Banders
People who are responsible for banding netted wildlife so they can be tracked are called banders in the United States. Banders are responsible for the animals caught and thus apply their training by looking for stress cues (for birds, these include panting, tiredness, closing of eyes, and raising of feathers). Without this caution, animals can severely injure themselves.
In the United States, in order to band a bird or bat, one must have a banding permit from U.S. Fish and Wildlife. The qualifications for permitting vary by species. There are different types of banding permits for birds: the Master Permit and the Sub permit. Master Permits are given to individuals who band on their own or who supervise banding operations. Sub Permits are given to individuals who will be supervised while banding by a person with a Master Permit. In order to receive a permit, one must complete an application and return it to the nearest banding office. Banders must ask for special authorization in their application to use mist nets, cannon nets, chemicals, or auxiliary markers.
See also
Bal-chatri traps to catch birds of prey (raptors)
References
Ornithological equipment and methods
Fowling
Nets (devices)
Environmental Sampling Equipment | Mist net | Biology | 1,949 |
165,755 | https://en.wikipedia.org/wiki/Pearl%20S.%20Buck | Pearl Comfort Sydenstricker Buck (June 26, 1892 – March 6, 1973) was an American writer and novelist. She is best known for The Good Earth, the best-selling novel in the United States in 1931 and 1932 and which won her the Pulitzer Prize in 1932. In 1938, Buck became the first American woman to win the Nobel Prize in Literature "for her rich and truly epic descriptions of peasant life in China" and for her "masterpieces", two memoir-biographies of her missionary parents.
Buck was born in West Virginia, but in October 1892, her parents took their 4-month-old baby to China. As the daughter of missionaries and later as a missionary herself, Buck spent most of her life before 1934 in Zhenjiang, with her parents, and in Nanjing, with her first husband. She and her parents spent their summers in a villa in Kuling, Mount Lu, Jiujiang, and it was during this annual pilgrimage that the young girl decided to become a writer. She graduated from Randolph-Macon Woman's College in Lynchburg, Virginia, then returned to China. From 1914 to 1932, after marrying John Lossing Buck, she served as a Presbyterian missionary, but she came to doubt the need for foreign missions. Her views became controversial during the Fundamentalist–Modernist controversy, leading to her resignation. After returning to the United States in 1935, she married the publisher Richard J. Walsh and continued writing prolifically. She became an activist and prominent advocate of the rights of women and racial equality, and wrote widely on Chinese and Asian cultures, becoming particularly well known for her efforts on behalf of Asian and mixed-race adoption.
Early life and education
Originally named Comfort, Pearl Sydenstricker was born in Hillsboro, West Virginia, to Caroline Maude (Stulting) (1857–1921) and Absalom Sydenstricker, of Dutch and German descent respectively. Her parents, Southern Presbyterian missionaries, were married on July 8, 1880 and moved to China shortly thereafter, but returned to the United States for Pearl's birth. When Pearl was five months old, the family returned to China, living first in Huai'an and then in 1896 moving to Zhenjiang, which was then known as Chingkiang in the Chinese postal romanization system, near the major city of Nanjing. In summer, she and her family spent time in Kuling. Her father built a stone villa in Kuling in 1897, and lived there until his death in 1931. It was during this annual summer pilgrimage in Kuling that the young girl decided to become a writer.
Of her siblings who survived into adulthood, Edgar Sydenstricker had a distinguished career with the U.S. Public Health Service and later the Milbank Memorial Fund, and Grace Sydenstricker Yaukey (1899–1994) wrote young adult books and books about Asia under the pen name Cornelia Spencer.
Pearl recalled in her memoir that she lived in "several worlds", one a "small, white, clean Presbyterian world of my parents", and the other the "big, loving merry not-too-clean Chinese world", and there was no communication between them. The Boxer Uprising (1899–1901) greatly affected the family; their Chinese friends deserted them, and Western visitors decreased. Her father, convinced that no Chinese could wish him harm, stayed behind as the rest of the family went to Shanghai for safety. A few years later, Buck was enrolled in Miss Jewell's School in Shanghai, and was dismayed at the racist attitudes there of other students, few of whom could speak any Chinese. Both of her parents felt strongly that Chinese were their equals; they forbade the use of the word heathen, and she was raised in a bilingual environment: tutored in English by her mother, in the local dialect by her Chinese playmates, and in classical Chinese by a Chinese scholar named Mr. Kung. She also read voraciously, especially, in spite of her father's disapproval, the novels of Charles Dickens, which she later said she read through once a year for the rest of her life.
In 1911, Buck left China to attend Randolph-Macon Woman's College in Lynchburg, Virginia, where she graduated Phi Beta Kappa in 1914 and was a member of Kappa Delta sorority.
Career
China
Although Buck had not intended to return to China, much less become a missionary, she quickly applied to the Presbyterian Board when her father wrote that her mother was seriously ill. In 1914, Buck returned to China. She married an agricultural economist missionary, John Lossing Buck, on May 13, 1917, and they moved to Suzhou, Anhui Province, a small town on the Huai River (not to be confused with the better-known Suzhou in Jiangsu Province). This is the region she describes in her books The Good Earth and Sons.
From 1920 to 1933, the Bucks made their home in Nanjing, on the campus of the University of Nanking, where they both had teaching positions. She taught English literature at this private, church-run university, and also at Ginling College and at the National Central University. In 1920, the Bucks had a daughter, Carol, who was afflicted with phenylketonuria that left her severely developmentally disabled. Buck had to have a hysterectomy due to complications of Carol's birth, leaving her unable to have more biological children. In 1921, Buck's mother died of a tropical disease, sprue, and shortly afterward her father moved in. In 1924, they left China for John Buck's year of sabbatical and returned to the United States for a short time, during which Pearl Buck earned a master's degree from Cornell University. In 1925, the Bucks adopted a child named Janice (later surnamed Walsh). That autumn, they returned to China.
The tragedies and dislocations that Buck suffered in the 1920s reached a climax in March 1927, during the "Nanking Incident". In a confused battle involving elements of Chiang Kai-shek's Nationalist troops, Communist forces, and assorted warlords, several Westerners were murdered. Since her father Absalom insisted, as he had in 1900 in the face of the Boxers, the family decided to stay in Nanjing until the battle reached the city. When violence broke out, a poor Chinese family invited them to hide in their hut while the family house was looted. The family spent a day terrified and in hiding, after which they were rescued by American gunboats. They traveled to Shanghai and then sailed to Japan, where they stayed for a year, after which they moved back to Nanjing. Buck later said that this year in Japan showed her that not all Japanese were militarists. When she returned from Japan in late 1927, Buck devoted herself in earnest to the vocation of writing. Friendly relations with prominent Chinese writers of the time, such as Xu Zhimo and Lin Yutang, encouraged her to think of herself as a professional writer. She wanted to fulfill the ambitions denied to her mother, but she also needed money to support herself if she left her marriage, which had become increasingly lonely. Since the mission board could not provide it, she also needed money for Carol's specialized care.
Buck traveled once more to the United States in 1929 to find long-term care for Carol, eventually placing her in the Vineland Training School in New Jersey. Buck served on the Board of Trustees for the school, at which Carol lived for the rest of her life and where she eventually died in 1992 at age 72. While Buck was in the United States, Richard J. Walsh, editor at John Day publishers in New York, accepted her novel East Wind: West Wind. She and Walsh began a relationship that would result in marriage and many years of professional teamwork.
Back in Nanking, Buck retreated every morning to the attic of her university house, and within the year, completed the manuscript for The Good Earth. She was involved in the charity relief campaign for the victims of the 1931 China floods, writing a series of short stories describing the plight of refugees, which were broadcast on the radio in the United States and later published in her collected volume The First Wife and Other Stories.
When her husband took the family to Ithaca, New York the following year, Buck accepted an invitation to address a luncheon of Presbyterian women at the Hotel Astor in New York City. Her talk was titled "Is There a Case for the Foreign Missionary?" and her answer was a barely qualified "no". She told her American audience that she welcomed Chinese to share her Christian faith, but argued that China did not need an institutional church dominated by missionaries who were too often ignorant of China and arrogant in their attempts to control it. When the talk was published in Harper's Magazine, the scandalized reaction led Buck to resign her position with the Presbyterian Board. In 1934, Buck left China, believing she would return, while her husband remained.
United States
Buck divorced her husband in Reno, Nevada on June 11, 1935, and she married Richard Walsh that same day. He reportedly offered her advice and affection which, her biographer concludes, "helped make Pearl's prodigious activity possible". The couple moved with Janice to Green Hills Farm in Bucks County, Pennsylvania, which they quickly set about filling with adopted children. Two sons were brought home as infants in 1936 and followed by another son and daughter in 1937.
Following the Communist Revolution in 1949, Buck was repeatedly refused all attempts to return to her beloved China. Her 1962 novel Satan Never Sleeps described the Communist tyranny in China. During the Cultural Revolution, Buck, as a preeminent American writer of Chinese village life, was denounced as an "American cultural imperialist". Buck was "heartbroken" when she was prevented from visiting China with Richard Nixon in 1972.
Nobel Prize in Literature
In 1938 the Nobel Prize committee in awarding the prize said:
In her speech to the Academy, Buck took as her topic "The Chinese Novel". She explained, "I am an American by birth and by ancestry", but "my earliest knowledge of story, of how to tell and write stories, came to me in China." After an extensive discussion of classic Chinese novels, especially Romance of the Three Kingdoms, All Men Are Brothers, and Dream of the Red Chamber, she concluded that in China "the novelist did not have the task of creating art but of speaking to the people." Her own ambition, she continued, had not been trained toward "the beauty of letters or the grace of art." In China, the task of the novelist differed from the Western artist: "To farmers he must talk of their land, and to old men he must speak of peace, and to old women he must tell of their children, and to young men and women he must speak of each other." And like the Chinese novelist, she concluded, "I have been taught to want to write for these people. If they are reading their magazines by the million, then I want my stories there rather than in magazines read only by a few."
Humanitarian efforts
Buck was committed to a range of issues that were largely ignored by her generation. Many of her life experiences and political views are described in her novels, short stories, fiction, children's stories, and the biographies of her parents entitled Fighting Angel (on Absalom) and The Exile (on Carrie). She wrote on diverse subjects, including women's rights, Asian cultures, immigration, adoption, missionary work, war, the atomic bomb (Command the Morning), and violence. Long before it was considered fashionable or politically safe to do so, Buck challenged the American public by raising consciousness on topics such as racism, sex discrimination and the plight of Asian war children. Buck combined the careers of wife, mother, author, editor, international spokesperson, and political activist. Buck became well-known as an advocate for civil rights, women’s rights, and the disability rights.
In 1949, after finding that existing adoption services considered Asian and mixed-race children unadoptable, Buck founded the first permanent foster home for US-born mixed-race children of Asian descent, naming it The Welcome Home. The foster home was located in a 16-room farmhouse in Pennsylvania next door to Buck's own home, Green Hill Farm, and Buck was actively involved in everything from planning the children's diets to buying their clothing. Among the home's Board of Directors were librettist Oscar Hammerstein II and his second wife, interior designer Dorothy, composer Richard Rodgers, seed company tycoon David Burpee and his wife Lois and author James A. Michener. As more and more children were referred to the foster home, however, it quickly became apparent that it couldn't accommodate them all and adoptive homes were needed. Welcome Home was turned into the first international, interracial adoption agency, and Buck began actively promoting the adoption of mixed-race children to the American public. In an effort to overcome the longstanding public view that such children were inferior and undesirable, Buck claimed in interviews and speeches that "hybrid" children of interracial backgrounds were actually genetically superior to other children in terms of intelligence and health. She and her husband Richard then adopted two mixed-race daughters from overseas themselves: an Afro-German girl in 1951 and an Afro-Japanese girl in 1957, giving her eight children in total. In 1967 she turned over most of her earnings—more than $7 million— to the adoption agency to help with costs.
Buck established the Pearl S. Buck Foundation (name changed to Pearl S. Buck International in 1999) to "address poverty and discrimination faced by children in Asian countries." In 1964, she opened the Opportunity Center and Orphanage in South Korea, and later offices were opened in Thailand, the Philippines, and Vietnam. When establishing Opportunity House, Buck said, "The purpose ... is to publicize and eliminate injustices and prejudices suffered by children, who, because of their birth, are not permitted to enjoy the educational, social, economic and civil privileges normally accorded to children."In 1960, after a long decline in health that included a series of strokes, Buck's husband Richard Walsh died. She renewed a warm relationship with William Ernest Hocking, who died in 1966. Buck then withdrew from many of her old friends and quarreled with others.
In 1962 Buck asked the Israeli Government for clemency for Adolf Eichmann, the Nazi war criminal who was complicit in the deaths of six million Jews during World War II, as she and others believed that carrying out capital punishment against Eichmann could be seen as an act of vengeance, especially since the war had ended.
During a December 17, 1962 visit to the Kennedy White House, Buck urged the Kennedy administration to help resolve People's Republic of China-Taiwan relations by supporting de facto independence of Taiwan for a 10 to 25 year period with an agreement that afterwards a plebiscite could be held based on a negotiated settlement.
Buck’s ties with her native state remained strong. In the title essay of My Mother’s House, a small book written by Buck and others to help raise funds for the Birthplace Museum, she paid tribute to the house her mother had cherished while living far away: ‘‘For me it was a living heart in the country I knew was my own but which was strange to me until I returned to the house where I was born. In the late 1960s, Buck toured West Virginia to raise money to preserve her family farm in Hillsboro, West Virginia. Today the Pearl S. Buck Birthplace is a historic house museum and cultural center. She hoped the house would "belong to everyone who cares to go there," and serve as a "gateway to new thoughts and dreams and ways of life." Former U.S. President George H. W. Bush toured the Pearl S. Buck House in October 1998. He expressed that he, like millions of other Americans, had gained an appreciation for the Chinese people through Buck's writing.
Final years
In the mid-1960s, Buck increasingly came under the influence of Theodore Harris, a former dance instructor, who became her confidant, co-author, and financial advisor. She soon depended on him for all her daily routines, and placed him in control of Welcome House and the Pearl S. Buck Foundation. Harris, who was given a lifetime salary as head of the foundation, created a scandal for Buck when he was accused of mismanaging the foundation, diverting large amounts of the foundation's funds for his friends' and his own personal expenses, and treating staff poorly. Buck defended Harris, stating that he was "very brilliant, very high strung and artistic." Before her death, Buck signed over her foreign royalties and her personal possessions to Creativity Inc., a foundation controlled by Harris.
Death
Pearl S. Buck died of lung cancer on March 6, 1973, in Danby, Vermont.
She was interred on Green Hills Farm in Perkasie, Pennsylvania. She designed her own tombstone. Her name was not inscribed in English on her tombstone. Instead, the grave marker is inscribed with the Chinese characters 賽珍珠 () representing the name Pearl Sydenstricker; specifically, Sai is the sound of the first syllable of her last name (Chinese last names come first), and Zhenzhu is the Chinese word for pearl.
Buck left behind three contradictory wills, resulting in a three-way legal dispute over her estate between her financial advisor Theodore Harris, the nonprofit Pearl Buck Foundation, and her seven adopted children. After a six-year battle, the dispute was settled in her children's favor after both Harris and the Pearl Buck Foundation dropped their claims (the latter in return for a financial settlement from Buck's children).
Legacy
Many contemporary reviewers praised Buck's "beautiful prose", even though her "style is apt to degenerate into over-repetition and confusion". Robert Benchley wrote a parody of The Good Earth that emphasised these qualities. Peter Conn, in his biography of Buck, argues that despite the accolades awarded to her, Buck's contribution to literature has been mostly forgotten or deliberately ignored by America's cultural gatekeepers. Kang Liao argues that Buck played a "pioneering role in demythologizing China and the Chinese people in the American mind". Phyllis Bentley, in an overview of Buck's work published in 1935, was altogether impressed: "But we may say at least that for the interest of her chosen material, the sustained high level of her technical skill, and the frequent universality of her conceptions, Mrs. Buck is entitled to take rank as a considerable artist. To read her novels is to gain not merely knowledge of China but wisdom about life." These works aroused considerable popular sympathy for China, and helped foment a more critical view of Japan and its aggression.
Chinese-American author Anchee Min said she "broke down and sobbed" after reading The Good Earth for the first time as an adult, which she had been forbidden to read growing up in China during the Cultural Revolution. Min said Buck portrayed the Chinese peasants "with such love, affection and humanity" and it inspired Min's novel Pearl of China (2010), a fictional biography about Buck.
In 1973, Buck was inducted into the National Women's Hall of Fame. Buck was honored in 1983 with a 5¢ Great Americans series postage stamp issued by the United States Postal Service In 1999 she was designated a Women's History Month Honoree by the National Women's History Project.
Buck's former residence at Nanjing University is now the Pearl S. Buck Memorial House or in Mandarin 賽珍珠紀念館 () along the West Wall of the university's north campus.
Pearl Buck's papers and literary manuscripts are currently housed at Pearl S. Buck International and the West Virginia & Regional History Center.
Selected bibliography
Autobiographies
My Several Worlds: A Personal Record (New York: John Day, 1954)
My Several Worlds – abridged for younger readers by Cornelia Spencer (New York: John Day, 1957)
A Bridge for Passing (New York: John Day, 1962) – autobiographical account of the filming of Buck's children's book, The Big Wave
Biographies
The Exile: Portrait of an American Mother (New York: John Day, 1936) – about her mother, Caroline Stulting Sydenstricker (1857–1921); serialized in Woman's Home Companion magazine (10/1935–3/1936)
Fighting Angel: Portrait of a Soul (New York: Reynal & Hitchcock, 1936) – about her father, Absalom Sydenstricker (1852–1931)
The Spirit and the Flesh (New York: John Day, 1944) – includes The Exile: Portrait of an American Mother and Fighting Angel: Portrait of a Soul
Novels
East Wind: West Wind (New York: John Day, 1930) – working title Winds of Heaven
The Good Earth (New York: John Day, 1931); The House of Earth trilogy #1 – made into a feature film The Good Earth (MGM, 1937)
Sons (New York: John Day, 1933); The House of Earth trilogy #2; serialized in Cosmopolitan (4–11/1932)
A House Divided (New York: Reynal & Hitchcock, 1935); The House of Earth trilogy #3
The House of Earth (trilogy) (New York: Reynal & Hitchcock, 1935) – includes: The Good Earth, Sons, A House Divided
All Men Are Brothers (New York: John Day, 1933) – a translation by Buck of the Chinese classical prose epic Water Margin (Shui Hu Zhuan)
The Mother (New York: John Day, 1933) – serialized in Cosmopolitan (7/1933–1/1934)
This Proud Heart (New York: Reynal & Hitchcock, 1938) – serialized in Good Housekeeping magazine (8/1937–2/1938)
The Patriot (New York: John Day, 1939)
Other Gods: An American Legend (New York: John Day, 1940) – excerpt serialized in Good Housekeeping magazine as "American Legend" (12/1938–5/1939)
China Sky (New York: John Day, 1941) – China trilogy #1; serialized in Collier's Weekly magazine (2–4/1941); made into a feature film China Sky (film) (RKO, 1945)
China Gold: A Novel of War-torn China (New York: John Day, 1942) – China trilogy #2; serialized in Collier's Weekly magazine (2–4/1942)
Dragon Seed (New York: John Day, 1942) – serialized in Asia (9/1941–2/1942); made into a feature film Dragon Seed (MGM, 1944)
The Promise (New York: John Day, 1943) – sequel to Dragon Seed; serialized in Asia and the Americas (Asia) (11/1942–10/1943)
China Flight (Philadelphia: Triangle Books/Blakiston Company, 19453) – China trilogy #3; serialized in Collier's Weekly magazine (2–4/1943)
Portrait of a Marriage (New York: John Day, 1945) – illustrated by Charles Hargens
The Townsman (New York: John Day, 1945) – as John Sedges
Pavilion of Women (New York: John Day, 1946) – made into a feature film Pavilion of Women (Universal Focus, 2001)
The Angry Wife (New York: John Day, 1947) – as John Sedges
Peony (New York: John Day, 1948) – published in the UK as The Bondmaid (London: T. Brun, 1949); – serialized in Cosmopolitan (3–4/1948)
Kinfolk (New York: John Day, 1949) – serialized in Ladies' Home Journal (10/1948–2/1949)
The Long Love (New York: John Day, 1949) – as John Sedges
God's Men (New York: John Day, 1951)
Sylvia (1951) – alternate title No Time for Love, serialized in Redbook magazine (1951)
Bright Procession (New York: John Day, 1952) – as John Sedges
The Hidden Flower (New York: John Day, 1952) – serialized in Woman's Home Companion magazine (3–4/1952)
Come, My Beloved (New York: John Day, 1953)
Voices in the House (New York: John Day, 1953) – as John Sedges
Imperial Woman The Story of the Last Empress of China (New York: John Day, 1956) – about Empress Dowager Cixi; serialized in Woman's Home Companion (3–4/1956)
Letter from Peking (New York: John Day, 1957)
American Triptych: Three John Sedges Novels (New York: John Day, 1958) – includes The Townsman, The Long Love, Voices in the House
Command the Morning (New York: John Day, 1959)
Satan Never Sleeps (New York: Pocket Books, 1962) – 1962 film Satan Never Sleeps, also known as The Devil Never Sleeps and Flight from Terror
The Living Reed A Novel of Korea (New York: John Day, 1963)
Death in the Castle (New York: John Day, 1965)
The Time Is Noon (New York: John Day, 1966)
The New Year (New York: John Day, 1968)
The Three Daughters of Madame Liang (London: Methuen, 1969)
Mandala: A Novel of India (New York: John Day, 1970)
The Goddess Abides (New York: John Day, 1972)
All under Heaven (New York: John Day, 1973)
The Rainbow (New York: John Day, 1974)
The Eternal Wonder (believed to have been written shortly before her death, published in October 2013)
Non-fiction
Is There a Case for Foreign Missions? (New York: John Day, 1932)
The Chinese Novel: Nobel Lecture Delivered before the Swedish Academy at Stockholm, December 12, 1938 (New York: John Day, 1939)
Of Men and Women (New York: John Day, 1941) – Essays
American Unity and Asia (New York: John Day, 1942) – UK edition titled Asia and Democracy, London: Macmillan, 1943) – Essays
What America Means to Me (New York: John Day, 1943) – UK edition (London: Methuen, 1944) – Essays
Talk about Russia (with Masha Scott) (New York: John Day, 1945) – serialized in Asia and the Americas magazine (Asia) as Talks with Masha (1945)
Tell the People: Talks with James Yen about the Mass Education Movement (New York: John Day, 1945)
How It Happens: Talk about the German People, 1914–1933, with Erna von Pustau (New York: John Day, 1947)
American Argument with Eslanda Goode Robeson (New York: John Day, 1949)
The Child Who Never Grew (New York: John Day, 1950)
The Man Who Changed China: The Story of Sun Yat-sen (New York: John Day, 1953) – for children
Friend to Friend: A Candid Exchange between Pearl S. Buck and Carlos P. Romulo (New York: John Day, 1958)
For Spacious Skies (1966)
The People of Japan (1966)
To My Daughters, with Love (New York: John Day, 1967)
The Kennedy Women (1970)
China as I See It (1970)
The Story Bible (1971)
Pearl S. Buck's Oriental Cookbook (1972)
Words of Love (1974)
Short stories
Collections
The First Wife and Other Stories (London: Methuen, 1933) – includes: "The First Wife", "The Old Mother", "The Frill", "The Quarrell", "Repatriated", "The Rainy Day", Wang Lung", "The Communist", "Father Andrea", "The New Road", "Barren Spring", *"The Refugees", "Fathers and Mothers", "The Good River"
Today and Forever: Stories of China (New York: John Day, 1941) – includes: "The Lesson", The Angel", "Mr. Binney's Afternoon", "The Dance", "Shanghai Scene", "Hearts Come Home", "His Own Country", "Tiger! Tiger!", "Golden flower", "The Face of Buddha", "Guerrilla Mother", "A Man's Foes", "The Old Demon"
Twenty-seven Stories (Garden City, NY: Sun Dial Press, 1943) – includes (from The First Wife and Other Stories): "The First Wife", "The Old Mother", "The Frill", "The Quarrell", "Repatriated", "The Rainy Day", Wang Lung", "The Communist", "Father Andrea", "The New Road", "Barren Spring", *"The Refugees", "Fathers and Mothers", "The Good River"; and (from Today and Forever: Stories of China): "The Lesson", The Angel", "Mr. Binney's Afternoon", "The Dance", "Shanghai Scene", "Hearts Come Home", "His Own Country", "Tiger! Tiger!", "Golden flower", "The Face of Buddha", "Guerrilla Mother", "A Man's Foes", "The Old Demon"
Far and Near: Stories of Japan, China, and America (New York: John Day, 1947) – includes: "The Enemy", "Home Girl", "Mr. Right", "The Tax Collector", "A Few People", "Home to Heaven", "Enough for a Lifetime", "Mother and Sons", "Mrs. Mercer and Her Self", "The Perfect Wife", "Virgin birth", "The Truce", "Heat Wave", "The One Woman"
Fourteen Stories (New York: John Day, 1961) – includes: "A Certain Star," "The Beauty", "Enchantment", "With a Delicate Air", "Beyond Language", "Parable of Plain People", "The Commander and the Commissar", "Begin to Live", "The Engagement", "Melissa", "Gift of Laughter", "Death and the Dawn", "The Silver Butterfly", "Francesca"
Hearts Come Home and Other Stories (New York: Pocket Books, 1962)
Stories of China (1964)
Escape at Midnight and Other Stories (1964)
The Good Deed, and other Stories of Asia, Past and Present (1970)
East and West Stories (1975)
Secrets of the Heart: Stories (1976)
The Lovers and Other Stories (1977)
Mrs. Stoner and the Sea and Other Stories (1978)
The Woman Who Was Changed and Other Stories (1979)
Beauty Shop Series: "Revenge in a Beauty Shop" (1939) – original title "The Perfect Hairdresser"
Beauty Shop Series: "Gold Mine" (1940)
Beauty Shop Series: "Mrs. Whittaker's Secret"/"The Blonde Brunette" (1940)
Beauty Shop Series: "Procession of Song" (1940)
Beauty Shop Series: "Snake at the Picnic" (1940) – published as "Seed of Sin" (1941)
Beauty Shop Series: "Seed of Sin" (1941) – published as "Snake at the Picnic (1940)
Individual short stories
Unknown title (1902) – first published story, pen name "Novice", Shanghai Mercury
"The Real Santa Claus" (c. 1911)
"Village by the Sea" (1911)
"By the Hand of a Child" (1912)
"The Hours of Worship" (1914)
"When 'Lof' Comes" (1914)
"The Clutch of the Ancients" (1924)
"The Rainy Day" (c. 1925)
"A Chinese Woman Speaks" (1926)
"Lao Wang, the Farmer" (1926)
"The Solitary Priest" (1926)
"The Revolutionist" (1928) – later published as "Wang Lung" (1933)
"The Wandering Little God" (1928)
"Father Andrea" (1929)
"The New Road" (1930)
"Singing to her Death" (1930)
"The Barren Spring" (1931)
"The First Wife" (1931)
"The Old Chinese Nurse" (1932)
"The Quarrel" (1932)
"The Communist" (1933)
"Fathers and Mothers" (1933)
"The Frill" (1933)
"Hidden is the Golden Dragon" (1933)
"The Lesson" (1933) – later published as "No Other Gods" (1936; original title used in short story collections)
"The Old Mother" (1933)
"The Refugees" (1933)
"Repatriated" (1933)
"The Return" (1933)
"The River" (1933) – later published as "The Good River" (1939)
"The Two Women" (1933)
"The Beautiful Ladies" (1934) – later published as "Mr. Binney's Afternoon" (1935)
"Fool's Sacrifice" (1934)
"Shanghai Scene" (1934)
"Wedding and Funeral" (1934)
"Between These Two" (1935)
"The Dance" (1935)
"Enough for a Lifetime" (1935)
"Hearts Come Home" (1935)
"Heat Wave" (1935)
"His Own Country" (1935)
"The Perfect Wife" (1935)
"Vignette of Love" (1935) – later published as "Next Saturday and Forever" (1977)
"The Crusade" (1936)
"Strangers Are Kind" (1936)
"The Truce" (1936)
"What the Heart Must" (1937) – later published as "Someone to Remember" (1947)
"The Angel" (1937)
"Faithfully" (1937)
"Ko-Sen, the Sacrificed" (1937)
"Now and Forever" (1937) – serialized in Woman's Home Companion magazine (10/1936–3/1937)
"The Woman Who Was Changed" (1937) – serialized in Redbook magazine (7–9/1937)
"The Pearls of O-lan" – from The Good Earth (1938)
"Ransom" (1938)
"Tiger! Tiger!" (1938)
"Wonderful Woman" (1938) – serialized in Redbook magazine (6–8/1938)
"For a Thing Done" (1939) – originally titled "While You Are Here"
"The Old Demon" (1939) – reprinted in Great Modern Short Stories: An Anthology of Twelve Famous Stories and Novelettes, selected, and with a foreword and biographical notes by Bennett Cerf (New York: The Modern library, 1942)
"The Face of Gold" (1940, in Saturday Evening Post) – later published as "The Face of Buddha" (1941)
"Golden Flower" (1940)
"Iron" (1940) – later published as "A Man's Foes" (1940)
"The Old Signs Fail" (1940)
"Stay as You Are" (1940) – serialized in Cosmopolitan (3–7/1940)
"There Was No Peace" (1940) – later published as "Guerrilla Mother" (1941)
"Answer to Life" (novella; 1941)
"More Than a Woman" (1941) – originally titled "Deny It if You Can"
"Our Daily Bread" (1941) – originally titled "A Man's Daily Bread, 1–3", serialized in Redbook magazine (2–4/1941), longer version published as Portrait of a Marriage (1945)
The Enemy (1942, Harper's Magazine) – staged by the Indian "Aamra Kajon" (Drama Society), on the Bengal Theatre Festival 2019
"John-John Chinaman" (1942) – original title "John Chinaman"
"The Long Way 'Round" – serialized in Cosmopolitan (9/1942–2/1943)
"Mrs. Barclay's Christmas Present" (1942) – later published as "Gift of Laughter" (1943)
"Descent into China" (1944)
"Journey for Life" (1944) – originally titled "Spark of Life"
"The Real Thing" (1944) – serialized in Cosmopolitan (2–6/1944); originally intendeds as a serial "Harmony Hill" (1938)
"Begin to Live" (1945)
"Mother and Sons" (1945)
"A Time to Love" (1945) – later published under its original title "The Courtyards of Peace" (1969)
"Big Tooth Yang" (1946) – later published as "The Tax Collector" (1947)
"The Conqueror's Girl" (1946) – later published as "Home Girl" (1947)
"Faithfully Yours" (1947)
"Home to Heaven" (1947)
"Incident at Wang's Corner" (1947) – later published as "A Few People" (1947)
"Mr. Right" (1947)
"Mrs. Mercer and Her Self" (1947)
"The One Woman" (1947)
"Virgin Birth" (1947)
"Francesca" (Good Housekeeping magazine, 1948)
"The Ember" (1949)
"The Tryst" (1950)
"Love and the Morning Calm" – serialized in Redbook magazine (1–4/1951)
"The Man Called Dead" (1952)
"Death and the Spring" (1953)
"Moon over Manhattan" (1953)
"The Three Daughters" (1953)
"The Unwritten Rules" (1953)
"The Couple Who Lived on the Moon" (1953) – later published as "The Engagement" (1961)
"A Husband for Lili" (1953) – later published as "The Good Deed" (1969)
"The Heart's Beginning" (1954)
"The Shield of Love" (1954)
"Christmas Day in the Morning" (1955) – later published as "The Gift That Lasts a Lifetime"
"Death and the Dawn" (1956)
"Mariko" (1956)
"A Certain Star" (1957)
"Honeymoon Blues" (1957)
"China Story" (1958)
"Leading Lady" (1958) – alternately titled "Open the Door, Lady"
"The Secret" (1958)
"With a Delicate Air" (1959)
"The Bomb (Dr. Arthur Compton)" (1959)
"Heart of a Man" (1959)
"Melissa" (1960)
"The Silver Butterfly" (1960)
"The Beauty" (1961)
"Beyond Language" (1961)
"The Commander and the Commissar" (1961)
"Enchantment" (1961)
"Parable of Plain People" (1961)
"A Field of Rice" (1962)
"A Grandmother's Christmas" (1962) – later published as "This Day to Treasure" (1972)
""Never Trust the Moonlight" (1962) – later published as "The Green Sari" (1962)
"The Cockfight, 1963
"A Court of Love" (1963)
"Escape at Midnight" (1963)
"The Lighted Window" (1963)
"Night Nurse" (1963)
"The Sacred Skull" (1963)
"The Trap" (1963)
"India, My India" (1964)
"Ranjit and the Tiger" (1964)
"A Certain Wisdom" (1967, in Woman's Day magazine)
"Stranger Come Home" (1967)
"The House They Built" (1968, in Boys' Life magazine)
"The Orphan in My Home" (1968)
"Secrets of the Heart" (1968)
"All the Days of Love and Courage" 1969) – later published as "The Christmas Child" (1972)
"Dagger in the Dark" (1969)
"Duet in Asia" (1969; written 1953
"Going Home" (1969)
"Letter Home" (1969; written 1943)
"Sunrise at Juhu" (1969)
"Two in Love" (1970) – later published as "The Strawberry Vase" (1976)
"The Gifts of Joy" (1971)
"Once upon a Christmas" (1971)
"The Christmas Secret" (1972)
"Christmas Story" (1972)
"In Loving Memory" (1972) – later published as "Mrs. Stoner and the Sea" (1976)
"The New Christmas" (1972)
"The Miracle Child" (1973)
"Mrs. Barton Declines" (1973) – later published as "Mrs. Barton's Decline" and "Mrs. Barton's Resurrection" (1976)
"Darling Let Me Stay" (1975) – excerpt from "Once upon a Christmas" (1971)
"Dream Child" (1975)
"The Golden Bowl" (1975; written 1942)
"Letter from India" (1975)
"To Whom a Child is Born" (1975)
"Alive again" (1976)
"Come Home My Son" (1976)
"Here and Now" (1976; written 1941)
"Morning in the Park" (1976; written 1948)
"Search for a Star" (1976)
"To Thine Own Self" (1976)
"The Woman in the Waves" (1976; written 1953)
"The Kiss" (1977)
"The Lovers" (1977)
"Miranda" (1977)
"The Castle" (1979; written 1949)
"A Pleasant Evening" (1979; written 1948)
Christmas Miniature (New York: John Day, 1957) – in UK as Christmas Mouse (London: Methuen, 1959) – illustrated by Anna Marie Magagna
Christmas Ghost (New York: John Day, 1960) – illustrated by Anna Marie Magagna
Unpublished stories
"The Good Rich Man" (1937, unsold)
"The Sheriff" (1937, unsold)
"High and Mighty" (1938, unsold)
"Mrs. Witler's Husband" (1938, unsold)
"Mother and Daughter" (1938, unsold; alternate title "My Beloved")
"Mother without Child" (1940, unsold)
"Instead of Diamonds" (1953, unsold)
Unpublished stories, undated
"The Assignation" (submitted not sold)
"The Big Dance" (unsold)
"The Bleeding Heart" (unsold)
"The Bullfrog" (unsold)
"The Day at Dawn" (unpublished)
"The Director"
"Heart of the Jungle (submitted, unsold)
"Images" (sold but unpublished)
"Lesson in Biology" / "Useless Wife" (unsold)
"Morning in Okinawa" (unsold)
"Mrs. Jones of Jerrell Street" (unsold)
"One of Our People" (sold, unpublished)
"Summer Fruit" (unsold)
"Three Nights with Love" (submitted, unsold) – original title "More Than a Woman"
"Too Many Flowers" (unsold)
"Wang the Ancient" (unpublished)
"Wang the White Boy" (unpublished)
Stories: Date unknown
"Church Woman"
"Crucifixion"
"Dear Son"
"Escape Me Never" – alternate title of "For a Thing Done"
"The Great Soul"
"Her Father's Wife"
"Horse Face"
"Lennie"
"The Magic Dragon"
"Mrs. Jones of Jerrell Street" (unsold)
"Night of the Dance"
"One and Two"
"Pleasant Vampire"
"Rhoda and Mike"
"The Royal Family"
"The Searcher"
"Steam and Snow"
"Tinder and the Flame"
"The War Chest"
"To Work the Sleeping Land"
Children's books and stories
The Young Revolutionist (New York: John Day, 1932) – for children
Stories for Little Children (New York: John Day, 1940) – pictures by Weda Yap
"When Fun Begins" (1941)
The Chinese Children Next Door (New York: John Day, 1942)
The Water Buffalo Children (New York: John Day, 1943) – drawings by William Arthur Smith
Dragon Fish (New York: John Day, 1944) – illustrated by Esther Brock Bird
Yu Lan: Flying Boy of China (New York: John Day, 1945) – drawings by Georg T. Hartmann
The Big Wave (New York: John Day, 1948) – illustrated with prints by Hiroshige and Hokusai – for children
One Bright Day (New York: John Day, 1950) – published in the UK as One Bright Day and Other Stories for Children (1952)
The Beech Tree (New York: John Day, 1954) – illustrated by Kurt Werth – for children
"Johnny Jack and His Beginnings" (New York: John Day, 1954)
Christmas Miniature (1957) – published in the UK as The Christmas Mouse (1958)
"The Christmas Ghost" (1960)
"Welcome Child (1964)
"The Big Fight" (1965)
"The Little Fox in the Middle" (1966)
Matthew, Mark, Luke and John (New York: John Day, 1967) – set in South Korea
"The Chinese Storyteller" (1971)
"A Gift for the Children" (1973)
"Mrs Starling's Problem" (1973)
Awards
Pulitzer Prize for the Novel: The Good Earth (1932)
William Dean Howells Medal (1935)
Nobel Prize in Literature (1938)
Child Study Association of America's Children's Book Award (now Bank Street Children's Book Committee's Josette Frank Award): The Big Wave (1948)
Museums and historic houses
Several historic sites work to preserve and display artifacts from Pearl's profoundly multicultural life:
The Pearl S. Buck Summer Villa, in Kuling town, Mount Lu, Jiujiang, China
Pearl S. Buck House in Nanjing University, China
The Zhenjiang Pearl S. Buck Research Association and former residence in Zhenjiang, China
Pearl S. Buck Birthplace in Hillsboro, West Virginia
Green Hills Farm in Bucks County, Pennsylvania
The Pearl S. Buck Memorial Hall, Bucheon City, South Korea
See also
Christian feminism
List of female Nobel laureates
Notes
Further reading
Harris, Theodore F. (in consultation with Pearl S. Buck), Pearl S. Buck: a Biography (John Day, 1969. )
Theodore F. Harris (in consultation with Pearl S. Buck), Pearl S. Buck; a biography. Volume two: Her philosophy as expressed in her letters (John Day, 1971. )
.
Hunt, Michael H. "Pearl Buck-Popular Expert on China, 1931-1949." Modern China 3.1 (1977): 33-64.
Jean So, Richard. "Fictions of Natural Democracy: Pearl Buck, The Good Earth, and the Asian American Subject." Representations 112.1 (2010): 87-111.
Kang, Liao. Pearl S. Buck: A Cultural Bridge across the Pacific. (Westport, CT, London: Greenwood, Contributions to the Study of World Literature 77, 1997). .
Leong. Karen J. The China Mystique: Pearl S. Buck, Anna May Wong, Mayling Soong, and the Transformation of American Orientalism (Berkeley: University of California Press, 2005).
Lipscomb, Elizabeth Johnston, Frances E. Webb and Peter J. Conn, eds., The Several Worlds of Pearl S. Buck: Essays Presented at a Centennial Symposium, Randolph-Macon Woman's College, March 26–28, 1992. Westport, CT: Greenwood Press, Contributions in Women's Studies, 1994.
Shaffer, Robert. "Women and international relations: Pearl S. Buck's critique of the Cold War." Journal of Women's History 11.3 (1999): 151-175.
Spurling, Hilary. Burying the Bones: Pearl Buck in China (London: Profile, 2010)
Stirling, Nora B. Pearl Buck, a Woman in Conflict (Piscataway, NJ: New Century Publishers, 1983).
Suh, Chris. ""America's Gunpowder Women" Pearl S. Buck and the Struggle for American Feminism, 1937–1941." Pacific Historical Review 88.2 (2019): 175-207. online
{{citation|title= Het China-gevoel van Pearl S. Buck (The China-feeling of Pearl S. Buck |publisher = Uitgeverij Brandt |year= 2021|first= Bettine |last= Vriesekoop|author-link= Bettine Vriesekoop}}.
Wacker, Grant. "Pearl S. Buck and the Waning of the Missionary Impulse" Church history 72.4 (2003): 852-874.
Xi Lian. The Conversion of Missionaries: Liberalism in American Protestant Missions in China, 1907–1932. (University Park: Pennsylvania State University Press, 1997).
Mari Yoshihara. Embracing the East: White Women and American Orientalism. (New York: Oxford University Press, 2003).
External links
Digital collections
Physical collections
The Zhenjiang Pearl S. Buck Research Association, China (in Chinese & English)
University of Pennsylvania website dedicated to Pearl S. Buck
National Trust for Historic Preservation on the Pearl S. Buck House Restoration
The Pearl S. Buck Literary Manuscripts and Other Collections at the West Virginia & Regional History Collection, WVU Libraries
Spring, Kelly. "Pearl Buck". National Women's History Museum.
A House Divided Manuscript at Dartmouth College Library
Biographical information
Pearl S. Buck fuller bibliography at WorldCat
Presentation by Peter Conn on Pearl S. Buck: A Cultural Biography, March 5, 1997, C-SPAN
Other links
The Pearl S. Buck Birthplace in Pocahontas County West Virginia
Pearl S. Buck International
List of Works
Pearl Buck interviewed by Mike Wallace on The Mike Wallace Interview'' February 8, 1958
FBI Records: The Vault – Pearl Buck at fbi.gov
1892 births
1973 deaths
20th-century American novelists
20th-century American women writers
Activists from West Virginia
American autobiographers
American expatriates in China
American historical novelists
American human rights activists
American women human rights activists
American Nobel laureates
American Presbyterian missionaries
Female Christian missionaries
American women non-fiction writers
Children of American missionaries in China
American people of Dutch descent
American people of German descent
Christian novelists
Christian humanists
Cornell University alumni
Members of the Society of Woman Geographers
Academic staff of Nanjing University
Nobel laureates in Literature
Novelists from Pennsylvania
Novelists from West Virginia
Writers from West Virginia
Writers from Bucks County, Pennsylvania
People from Hillsboro, West Virginia
Presbyterian Church in the United States members
Presbyterian missionaries in China
Presbyterians from West Virginia
Pulitzer Prize for the Novel winners
Randolph College alumni
American women autobiographers
American women historical novelists
Women Nobel laureates
Writers from Philadelphia
Writers from Zhenjiang
American anti-communists
Members of the American Academy of Arts and Letters | Pearl S. Buck | Technology | 10,432 |
4,385,464 | https://en.wikipedia.org/wiki/Electronic%20tuner | In music, an electronic tuner is a device that detects and displays the pitch of musical notes played on a musical instrument. "Pitch" is the perceived fundamental frequency of a musical note, which is typically measured in Hertz. Simple tuners indicate—typically with an analog needle or dial, LEDs, or an LCD screen—whether a pitch is lower, higher, or equal to the desired pitch. Since the early 2010s, software applications can turn a smartphone, tablet, or personal computer into a tuner. More complex and expensive tuners indicate pitch more precisely. Tuners vary in size from units that fit in a pocket to 19" rack-mount units. Instrument technicians and piano tuners typically use more expensive, accurate tuners.
The simplest tuners detect and display tuning only for a single pitch—often "A" or "E"—or for a small number of pitches, such as the six used in the standard tuning of a guitar (E,A,D,G,B,E). More complex tuners offer chromatic tuning for all 12 pitches of the equally tempered octave. Some electronic tuners offer additional features, such as pitch calibration, temperament options, the sounding of a desired pitch through an amplifier plus speaker, and adjustable "read-time" settings that affect how long the tuner takes to measure the pitch of the note.
Among the most accurate tuning devices, strobe tuners work differently than regular electronic tuners. They are stroboscopes that flicker a light at the same frequency as the note. The light shines on a wheel that spins at a precise speed. The interaction of the light and regularly-spaced marks on the wheel creates a stroboscopic effect that makes the marks for a particular pitch appear to stand still when the pitch is in tune. These can tune instruments and audio devices more accurately than most non-strobe tuners. However, mechanical strobe units are expensive and delicate, and their moving parts require periodic servicing, so they are used mainly in applications that require higher precision, such as by professional instrument makers and repair experts.
Regular types
Regular electronic tuners contain either an input jack for electric instruments (usually a -inch patch cord input), a microphone, or a clip-on sensor (e.g., a piezoelectric pickup) or some combination of these inputs. Pitch detection circuitry drives some type of display (an analog needle, an LCD simulated image of a needle, LED lights, or a spinning translucent disk illuminated by a strobing backlight). Some tuners have an output, or through-put, so the tuner can connect 'in-line' from an electric instrument to an instrument amplifier or mixing console. Small tuners are usually battery powered. Many battery-powered tuners also have a jack for an optional AC power supply.
Most musical instruments generate a fairly complex waveform with multiple related frequency components. The fundamental frequency is the pitch of the note. Additional "harmonics" (also called "partials" or "overtones") give each instrument its characteristic timbre. As well, this waveform changes during the duration of a note. This means that for non-strobe tuners to be accurate, the tuner must process a number of cycles and use the pitch average to drive its display. Background noise from other musicians or harmonic overtones from the musical instrument can impede the electronic tuner from "locking" onto the input frequency. This is why the needle or display on regular electronic tuners tends to waver when a pitch is played. Small movements of the needle, or LED, usually represent a tuning error of 1 cent. The typical accuracy of these types of tuners is around ±3 cents. Some inexpensive LED tuners may drift by as much as ±9 cents.
"Clip-on" tuners typically attach to instruments with a spring-loaded clip that has a built-in contact microphone. Clipped onto a guitar headstock or violin scroll, these sense pitch even in loud environments, for example when other people are tuning.
Some guitar tuners fit into the instrument itself. Typical of these are the Sabine AX3000 and the "NTune" device. The NTune consists of a switching potentiometer, a wiring harness, illuminated plastic display disc, a circuit board and a battery holder. The unit installs in place of an electric guitar's existing volume knob control. The unit functions as a regular volume knob when not in tuner mode. To operate the tuner, the player pulls the volume knob up. The tuner disconnects the guitar's output so the tuning process is not amplified. The lights on the illuminated ring, under the volume knob, indicate the note being tuned. When the note is in tune a green "in tune" indicator light illuminates. After tuning is complete the musician pushes the volume knob back down, disconnecting the tuner from the circuit and re-connecting the pickups to the output jack.
Gibson guitars released a guitar model in 2008 called the Robot Guitar—a customized version of either the Les Paul or SG model. The guitar is fitted with a special tailpiece with in-built sensors that pick up the frequency of the strings. An illuminated control knob selects different tunings. Motorized tuning machines on the headstock automatically tune the guitar. In "intonation" mode, the device displays how much adjustment the bridge requires with a system of flashing LEDs on the control knob.
Regular needle, LCD and LED display tuners
A needle, LCD or regular LED type tuner uses a microprocessor to measure the average period of the waveform. It uses that information to drive the needle or array of lights. When the musician plays a single note, the tuner senses the pitch. The tuner then displays the pitch in relation to the desired pitch, and indicates whether the input pitch is lower, higher, or equal to the desired pitch. With needle displays, the note is in tune when the needle is in a 90° vertical position, with leftward or rightward deviations indicating that the note is flat or sharp, respectively. Tuners with a needle are often supplied with a backlight, so that the display can be read on a darkened stage.
For block LED or LCD display tuners, markings on the readout drift left if the note is flat and right if the note is sharp from the desired pitch. If the input frequency is matched to the desired pitch frequency the LEDs are steady in the middle and an 'in tune' reading is given.
Some LCDs mimic needle tuners with a needle graphic that moves in the same way as a genuine needle tuner. Somewhat misleadingly, many LED displays have a 'strobe mode' that mimics strobe tuners by scrolling the flashing of the LEDs cyclically to simulate the display of a true strobe. However, these are all just display options. The way a regular tuner 'hears' and compares the input note to a desired pitch is exactly the same, with no change in accuracy.
The least expensive models only detect and display a small number of pitches, often those pitches that are required to tune a given instrument (e.g., E, A, D, G, B, E of standard guitar tuning). While this type of tuner is useful for bands that only use stringed instruments such as guitar and electric bass, it is not that useful for tuning brass or woodwind instruments. Tuners at the next price point offer chromatic tuning, the ability to detect and assess all the pitches in the chromatic scale (e.g., C, C, D, D, etc.). Chromatic tuners can be used for B and E brass instruments, such as saxophones and horns. Many models have circuitry that automatically detects which pitch is being played, and then compares it against the correct pitch. Less expensive models require the musician to specify the target pitch via a switch or slider. Most low- and mid-priced electronic tuners only allow tuning to an equal temperament scale.
Electric guitar and bass players who perform concerts may use electronic tuners built into an effects pedal, often called a stomp box. These tuners have a rugged metal or heavy-duty plastic housing and a foot-operated switch to toggle between the tuner and a bypass mode. Professional guitarists may use a more expensive version of the LED tuner mounted in a rack-mount case with a larger range of LEDs for more accurate pitch display. On many electronic tuners, the user can select a different note—useful for, for example, dropping a guitar's tuning to a lower pitch (e.g., Dropped tuning). Many models also let the user select reference pitches other than A440. This is useful to some Baroque musicians who play period instruments at lower reference pitches—such as A=435. Some higher-priced electronic tuners support tuning to a range of different temperaments—a feature useful to some guitarists and harpsichord players.
Some expensive tuners also include an on-board speaker that can sound notes, either to facilitate tuning by ear or to act as a pitch reference point for intonation practice. Some of these tuners also provide an adjustable read time that controls at what time interval the circuitry assesses pitch. The combination of all the above features makes some tuners preferable for tuning instruments in an orchestra. These are sometimes called "orchestral tuners".
Clip-on
A clip-on tuner clips onto an instrument—such as onto the headstock of a guitar or the bell of a trombone. A vibration sensor built into the clip transmits the instrument vibrations to the tuning circuitry. The absence of a microphone makes these tuners immune to background noise, so musicians can tune in noisy environments, including while other musicians are tuning. The first clip-on tuner was made by Mark Wilson from the OnBoard Research Corporation, and was marketed as Intellitouch PT1.
Apps
Since the early 2010s, many chromatic and guitar tuner apps are available for Android and iOS smartphones.
Strobe tuners
Strobe tuners (the popular term for stroboscopic tuners) are the most accurate type of tuner . There are three types of strobe tuners: the mechanical rotating disk strobe tuner, an LED array strobe in place of the rotating disk, and "virtual strobe" tuners with LCDs or ones that work on personal computers. A strobe tuner shows the difference between a reference frequency and the musical note being played. Even the slightest difference between the two shows up as a rotating motion in the strobe display. The accuracy of the tuner is only limited by the internal frequency generator. The strobe tuner detects the pitch from either a TRS input jack or a built-in or external microphone connected to the tuner.
The first strobe tuner dates back to 1936 and was originally made by the Conn company; it was called the Stroboconn and was produced for approximately 40 years. However, these strobes are now mainly collector pieces. They had 12 strobe discs, driven by one motor. The gearing between discs was a very close approximation to the 12th root of two ratio. This tuner had an electrically driven temperature-compensated tuning fork; the electrical output of this fork was amplified to run the motor. The fork had sliding weights, an adjustment knob, and a dial to show the position of the weights. These weights permitted setting it to different reference frequencies (such as A4 = 435 Hz), although over a relatively narrow range, perhaps a whole tone. When set at A4 = 440 Hz the tuning fork produced a 55 Hz signal, which drove the four-pole 1650 RPM synchronous motor to which the A disc was mounted. (The other discs were all gear-driven off of this one.) Incoming audio was amplified to feed a long neon tube common to all 12 discs. Wind instrument players and repair people liked this tuner because it needed no adjustment to show different notes. Anyone who had to move this tuner around was less inclined to like it because of its size and weight: two record-player-sized cases of 30-40 pounds each.
The best-known brand in strobe tuner technology is Peterson Tuners who in 1967 marketed their first strobe tuner, the Model 400. Other companies, such as Sonic Research, TC Electronic, and Planet Waves, sell highly accurate LED-based true strobe tuners. Other LED tuners have a 'strobe mode' that emulates the appearance of a strobe. However, the accuracy of these tuners in strobe mode, while sufficient for most tuning, is no better than in any other mode, as they use the same technique as any basic tuner to measure frequency, only displaying it in a way that imitates a strobe tuner.
How it works
Mechanical strobe tuners have a series of lamps or LEDs powered by amplified audio from the instrument; they flash (or strobe) at the same frequency as the input signal. For instance, an 'A' played on a guitar's 6th string at the 5th fret has the frequency of 110 Hz when in tune. An 'A' played on the 1st string at the 5th fret vibrates at 440 Hz. As such, the lamps would flash either 110 or 440 times per second in the above examples. In front of these flashing lights is a motor-driven, translucent printed disc with rings of alternating transparent and opaque sectors.
This disc rotates at a fixed specific speed, set by the user. Each disc rotation speed is set to a particular frequency of the desired note. If the note being played (and making the lamps behind the disc flash) is at exactly the same frequency as the spinning of the disc, then the disc appears to be static from the strobing effect. If the note is out of tune then the pattern appears to be moving as the light flashing and the disc rotation are out of sync from each other. The more out of tune the played note is, the faster the pattern seems to be moving, although in reality it always spins at the same speed for a given note. Many good turntables for vinyl disc records have stroboscopic patterns lit by the incoming AC power (mains). The power frequency, either 50 or 60 Hz, serves as the reference, although commercial power frequency sometimes changes slightly (a few tenths of a percent) with varying load. Unless reference and measured quantity are interchanged, the operating principle is the same; the turntable speed is adjusted to stop drifting of the pattern.
As the disc has multiple bands, each with different spacings, each band can be read for different partials within one note. As such, extremely fine tuning can be obtained, because the user can tune to a particular partial within a given note. This is impossible on regular needle, LCD or LED tuners. The strobe system is about 30 times more accurate than a quality electronic tuner , being accurate to of a cent. Advertisements for the Sonic Research LED strobe claim that it is calibrated to ± 0.0017 cents and guaranteed to maintain an accuracy of ± 0.02 cents or of a cent.
Strobe units can often be calibrated for many tunings and preset temperaments and allow for custom temperament programming, stretched tuning, "sweetened" temperament tunings and Buzz Feiten tuning modifications. Due to their accuracy and ability to display partials even on instruments with a very short "voice" (e.g., notes of short duration), strobe tuners can perform tuning tasks that would be very difficult, if not impossible, for needle-type tuners. For instance, needle/LED display type tuners cannot track the signal to identify a tone of the Caribbean steelpan (often nicknamed the "steeldrum") due to its very short "voice". A tuner needs to be able to detect the first few partials for tuning such an instrument, which means that only a strobe tuner can be used for steelpan tuning. This is also true of the comb teeth used in mechanical musical instruments like Music Boxes and the like. In such cases, a technician has to physically remove metal from the tooth to reach the desired note. The metal teeth only resonate briefly when plucked. Great accuracy is required as once the metal is cut or filed away, the lost material cannot be replaced. As such, the strobe-type tuners are the unit of choice for such tasks. Tuners with an accuracy of better than 0.2 cent are required for guitar intonation tuning.
One of the most expensive strobe tuners is the Peterson Strobe Center, which has twelve separate mechanical strobe displays; one for each pitch of the equally tempered octave. This unit (about US$3,500) can tune multiple notes of a sound or chord, displaying each note's overtone sub-structure simultaneously. This gives an overall picture of tuning within a sound, note or chord that is not possible with most other tuning devices. (The TC Electronic Polytune can display the pitch accuracy of up to six pre-selected notes.) It is often used for tuning complex instruments and sound sources, or difficult-to-tune instruments where the technician requires a very accurate and complete aural picture of an instrument's output. For instance, when tuning musical bells, this model displays several of the bell's partials (hum, second partial, tierce, quint and nominal/naming note) as well as the prime, and each of their partials, on separate displays. The unit is heavy and fragile, and requires a regular maintenance schedule. Each of the twelve displays requires periodic re-calibration. It can be used to teach students about note substructures, which show on the separate strobing displays.
Strobe developments
Mechanical disc strobe tuners are expensive, bulky, delicate, and require periodic maintenance (keeping the motor that spins the disc at the correct speed, replacing the strobing LED backlight, etc.). For many, a mechanical strobe tuner is simply not practical for one or all of the above reasons. To address these issues, in 2001 Peterson Tuners added a line of non-mechanical electronic strobe tuners that have LCD dot-matrix displays mimicking a mechanical strobe disc display, giving a stroboscopic effect. In 2004 Peterson made a model of LCD strobe in a sturdy floor based "stomp box" for live on-stage use. Virtual strobe tuners are as accurate as standard mechanical disc strobe tuners. However, there are limitations to the virtual system compared to the disc strobes. Virtual strobes display fewer bands to read note information, and do not pick up harmonic partials like a disc strobe. Rather, each band on a virtual strobe represents octaves of the fundamental. A disc strobe provides "one band correspondence"—each band displays a particular frequency of the note being played. On the virtual strobe system, each band combines a few close frequencies for easier reading on the LCD. This is still extremely accurate for intoning and tuning most instruments—but, as of this writing, no virtual strobe tuner provides detailed information on partials.
Sonic Research and Planet Waves both released a true-strobe with a bank of LEDs arranged in a circle that gives a strobing effect based upon the frequency of the input note. Both LCD and LED display true strobes do not require mechanical servicing and are much cheaper than the mechanical types. As such, they are a popular option for musicians who want the accuracy of a strobe without the high cost and the maintenance requirements. However, LED strobe displays offer no information about the harmonic structure of a note, unlike LCD types, which do offer four bands of consolidated information.
Peterson released a PC-based virtual strobe tuner in 2008 called "StroboSoft". This computer software package has all the features of a virtual strobe, such as user-programmable temperaments and tunings. To use this tuner, a musician must have a computer next to the instrument to be tuned. An alternative is the PC-based strobe tuner TB Strobe Tuner with fewer functions.
In 2009 Peterson Tuners released a VirtualStrobe tuner as an application add-on for Apple's iPhone and iPod Touch.
As both mechanical and electronic strobes are still more expensive and arguably more difficult to use in order to achieve the desired results than ordinary tuners, their use is usually limited to those whose business it is accurately to intone and tune pianos, harps, and early instruments (such as harpsichords) on a regular basis: luthiers, instrument restorers and technicians – and instrument enthusiasts. These tuners make the intonation process more precise.
Uses
Classical music
In classical music, there is a longstanding tradition to tune "by ear", by adjusting the pitch of instruments to a reference pitch. In an orchestra, the oboe player gives an "A4", and the different instrument sections tune to this note. In chamber music, either one of the woodwind players gives an "A", or if none is present, one of the string players, usually the first violinist, bows their open "A" string. If an orchestra is accompanying a piano concerto, the first oboist takes the "A" from the piano and then plays this pitch for the rest of the orchestra.
Despite this tradition of tuning by ear, electronic tuners are still widely used in classical music. In orchestras the oboist often uses a high-end electronic tuner to ensure that their "A" is correct. As well, other brass or woodwind players may use electronic tuners to ensure that their instruments are correctly tuned. Classical performers also use tuners off-stage for practice purposes or to check their tuning (or, with the further aid of a speaker, to practice ear training). Electronic tuners are also used in opera orchestras for offstage trumpet effects. In offstage trumpet effects, trumpet players performs a melody from the backstage or from a hallway behind the stage, creating a haunting, muted effect. Since trumpet players cannot hear the orchestra, they cannot know whether or not their notes are in tune with the rest of the ensemble; to resolve this problem, some trumpet players use a high-end, sensitive tuner so that they can monitor the pitch of their notes.
Piano tuners, harp makers and the builders and restorers of early instruments, e.g. harpsichords, use high-end tuners to assist with their tuning and instrument building. Even piano tuners who work mostly "by ear" may use an electronic tuner to tune just a first key on the piano, e. g. the a' to 440 Hz, after which they proceed by means of octaves, approximate fifths and approximate fourths to tune the others. (In the twelve-tone equal temperament system dominant in classical and Western music, all intervals except the octave are slightly "mistuned" or compromised compared to more consonant just intervals.) They may also use electronic tuners to get a very out-of-tune piano roughly in pitch, after which point they tune by ear. Electronic tuning devices for keyboard instruments are for various reasons generally much more complex and therefore expensive than in the case of other widely used instruments.
Popular and folk music
In popular music, amateur and professional bands from styles as varied as country and heavy metal use electronic tuners to ensure that the guitars and electric bass are correctly tuned. In popular music genres such as rock music, there is a great deal of stage volume due to the use of drums and guitar amplifiers, so it can be difficult to tune "by ear". Electronic tuners are helpful aids at jam sessions where a number of players are sharing the stage, because it helps all of the players to have their instruments tuned to the same pitch, even if they have come to the session halfway through. Tuners are helpful with acoustic instruments, because they are more affected by temperature and humidity changes. An acoustic guitar or upright bass that is perfectly in tune backstage can change in pitch under the heat of the stage lights and from the humidity from thousands of audience members.
Tuners are used by guitar technicians who are hired by rock and pop bands to ensure that all of the band's instruments are ready to play at all times. Guitar technicians (often called guitar techs) tune all of the instruments (electric guitars, electric basses, acoustic guitars, mandolins, etc.) before the show, after they are played, and before they are used onstage. Guitar techs also retune instruments throughout the show. Whereas amateur musicians typically use a relatively inexpensive quartz tuner, guitar technicians typically use expensive, high-end tuners such as strobe tuners. Most strobe tuners, counter-intuitively, also use quartz crystal oscillators as time references, although the responses are processed differently by the different units.
Bell tuning
Strobe tuners are used in the tuning of bells, which require accurate tuning of many partials. The removal of metal from various parts of the bell shape is by a tuning lathe, and once too much metal has been removed it cannot be reversed. Hence accurate approach to the desired tuning partial is essential to prevent overshoot.
See also
References
Consumer electronics
Musical instrument parts and accessories | Electronic tuner | Technology | 5,287 |
2,601,173 | https://en.wikipedia.org/wiki/Short%20Message%20service%20center | A Short Message Service Center (SMSC) is a network element in the mobile telephone network. Its purpose is to store, forward, convert and deliver Short Message Service (SMS) messages.
The full designation of an SMSC according to 3GPP is Short Message Service - Service Center (SMS-SC).8522076203
Basic trajectories
SMS can be directed in several ways:
From mobile to another mobile - referred to as MO-MT (Mobile Originated - Mobile Terminated)
From mobile to a content provider (also known as Large Account / ESME) - referred to as MO-AT (Mobile Originated - Application Terminated)
From application to a mobile - referred to as AO-MT (Application Originated - Mobile Terminated)
Operation
The tasks of an SMSC can be described as
Reception of text messages (SMS) from wireless network users
Storage of text messages
Forwarding of text messages
Delivery of text messages (SMS) to wireless network users
Maintenance of unique time stamps in text messages
When a user sends a text message (SMS message) to another user, the message gets stored in the SMSC (Short Message Service Center), which delivers it to the destination user when they are available. This is a store and forward option.
An SMS center (SMSC) is responsible for handling the SMS operations of a wireless network.
When an SMS message is sent from a mobile phone, it will first reach an SMS center.
The SMS center then forwards the SMS message towards the destination.
The main duty of an SMSC is to route SMS messages and regulate the process. If the recipient is unavailable (for example, when the mobile phone is switched off), the SMSC will store the SMS CAR message.
It will forward the SMS message when the recipient is available and the message's expiry period is not exceeded.
SMSCs can be used to interface with other applications, for example a spreadsheet can interface with the SMSC allowing messages to be sent SMS from an Excel spreadsheet, or to send an SMS from Excel. Inbound messages to a long number or short code can also be passed through the SMSC allowing m2m communications or Telematics.
Validity period of an SMS message
An SMS message is stored temporarily in the SMS center if the recipient mobile phone is unavailable. It is possible on most mobile handsets to specify an expiry period after which the SMS message will be deleted from the SMS center. Once deleted, the SMS message will no longer be available for dispatch to the recipient mobile phone (even if it comes on line). The validity period should be regarded by the handset user as a request, as the SMSC itself can be configured to ignore or otherwise handle message delivery schedules.
Message status reports
The SMS sender needs to set a flag in the SMS message to notify the SMS center that they want the status report about the delivery of this SMS message. This is usually done by changing a setting on the mobile handset.
See also
Short Message Service technical realisation (GSM)
IS-41
SMPP
UCP/EMI
CIMD
Mobile technology
Telecommunications infrastructure
Text messaging | Short Message service center | Technology | 633 |
22,525,361 | https://en.wikipedia.org/wiki/Xenoy | Xenoy is a blend of plastics with many industrially-useful properties. It is typically polyester (polybutylene terephthalate, PBT, or polyethylene terephthalate, PET) and polycarbonate (PC): it is often labeled PBT+PC or PET+PC.
Xenoy resins can be created with recycled post-consumer PBT plastic, consuming less energy and yielding less carbon dioxide () in their manufacturing than traditional resins.
References
Plastics | Xenoy | Physics | 108 |
62,406,548 | https://en.wikipedia.org/wiki/Aidoc | Aidoc Medical is an Israeli technology company that develops computer-aided simple triage and notification systems. Aidoc has obtained FDA and CE mark approval for its stroke, pulmonary embolism, cervical fracture, intracranial hemorrhage, intra-abdominal free gas, and incidental pulmonary embolism algorithms.
Aidoc algorithms are in use in more than 900 hospitals and imaging centers, including Montefiore Nyack Hospital, LifeBridge Health, LucidHealth, Yale New Haven Hospital, Cedars-Sinai Medical Center, University of Rochester Medical Center, and Sheba Medical Center.
History
Aidoc was founded in 2016 by Elad Walach as the CEO, Michael Braginsky as the CTO and Guy Reiner as the VP. In April 2017, the company raised $7M, led by TLV Partners, and in April 2019, the company raised another $27M, led by Square Peg capital.
In August 2018, Aidoc gained FDA clearance for its intracranial hemorrhage system, and in May 2019 it received clearance for the pulmonary embolism system.
In January 2020, the system for detecting large-vessel occlusions (LVOs) in head CTA examinations obtained FDA clearance.
Products and market
Aidoc has developed a suite of artificial intelligence products that flag both time-sensitive and time-consuming (for the radiologist) abnormalities across the body. The algorithms are developed with large quantities of data to provide diagnostic aid for a broad set of pathologies. The company offers an array of algorithms that span across the body, including for intracranial hemorrhage, spine fractures (C, T & L), free air in the abdomen, pulmonary embolism, and more. It developed "Always-on AI", a term coined by Elad Walach that refers to a type of artificial intelligence that is "Always-on—constantly running in the background and automatically analyzing medical imaging data, identifying urgent findings, and sparing radiologists from "drowning" in vast amounts of irrelevant data.
Aidoc's solutions cover medical conditions prevalent in all settings (ED/inpatient/outpatient), including level 1 trauma centers, outpatient imaging centers, teleradiology groups and, are set up in over 200 medical centers worldwide. Notable customers include the University of Rochester Medical Center and Global Diagnostics Australia.
Clinical Research
A clinical study on Aidoc’ accuracy of deep convolutional neural networks for the detection of pulmonary embolism (PE) on CT pulmonary angiograms (CTPAs) was performed by the University Hospital of Basel and presented at the European Congress of Radiology, showing that the Aidoc algorithm reached 93% sensitivity and 95% specificity. Clinical research has also been performed to test the diagnostic performance of Aidoc's deep learning-based triage system for the flagging of acute findings in abdominal computed tomography (CT) examinations. Overall, the algorithm achieved 93% sensitivity (91/98, 7 false negatives) and 97% specificity (93/96, 3 false-positive) in the detection of acute abdominal findings.
Additional clinical research on Aidoc's Intracranial hemorrhage algorithm accuracy was presented at the European Congress of Radiology by Antwerp University Hospital, evaluating the use of its deep learning algorithm for the detection of intracranial hemorrhage on non-contrast enhanced CT of the brain. The University of Washington completed a study on the accuracy of Aidoc's intracranial hemorrhage algorithm.
References
External links
Official website
Medical technology companies of Israel
Medical expert systems
Radiology
Technology companies established in 2016
Applications of artificial intelligence
Health informatics
Israeli companies established in 2016 | Aidoc | Biology | 757 |
48,815,776 | https://en.wikipedia.org/wiki/Impedance%20microbiology | Impedance microbiology is a microbiological technique used to measure the microbial number density (mainly bacteria but also yeasts) of a sample by monitoring the electrical parameters of the growth medium. The ability of microbial metabolism to change the electrical conductivity of the growth medium was discovered by Stewart and further studied by other scientists such as Oker-Blom, Parson and Allison in the first half of 20th century. However, it was only in the late 1970s that, thanks to computer-controlled systems used to monitor impedance, the technique showed its full potential, as discussed in the works of Fistenberg-Eden & Eden, Ur & Brown and Cady.
Principle of operation
When a pair of electrodes are immersed in the growth medium, the system composed of electrodes and electrolyte can be modeled with the electrical circuit of Fig. 1, where Rm and Cm are the resistance and capacitance of the bulk medium, while Ri and Ci are the resistance and capacitance of the electrode-electrolyte interface. However, when frequency of the sinusoidal test signal applied to the electrodes is relatively low (lower than 1 MHz) the bulk capacitance Cm can be neglected and the system can be modeled with a simpler circuit consisting only of a resistance Rs and a capacitance Cs in series. The resistance Rs accounts for the electrical conductivity of the bulk medium while the capacitance Cs is due to the capacitive double-layer at the electrode-electrolyte interface. During the growth phase, bacterial metabolism transforms uncharged or weakly charged compounds of the bulk medium in highly charged compounds that change the electrical properties of the medium. This results in a decrease of resistance Rs and an increase of capacitance Cs.
In impedance microbiology technique works this way, the sample with the initial unknown bacterial concentration (C0) is placed at a temperature favoring bacterial growth (in the range 37 to 42 °C if mesophilic microbial population is the target) and the electrical parameters Rs and Cs are measured at regular time intervals of few minutes by means of a couple of electrodes in direct contact with the sample.
Until the bacterial concentration is lower than a critical threshold CTH the electrical parameters Rs and Cs remain essentially constant (at their baseline values). CTH depends on various parameters such as electrode geometry, bacterial strain, chemical composition of the growth medium etc., but it is always in the range 106 to 107 cfu/ml.
When the bacterial concentration increases over CTH, the electrical parameters deviate from their baseline values (generally in the case of bacteria there is a decrease of Rs and an increase of Cs, the opposite happens in the case of yeasts).
The time needed for the electrical parameters Rs and Cs to deviate from their baseline value is referred as Detect Time (DT) and is the parameter used to estimate the initial unknown bacterial concentration C0.
In Fig. 2 a typical curve for Rs as well as the corresponding bacterial concentration are plotted vs. time. Fig. 3 shows typical Rs curves vs time for samples characterized by different bacterial concentration. Since DT is the time needed for the bacterial concentration to grow from the initial value C0 to CTH, highly contaminated samples are characterized by lower values of DT than samples with low bacterial concentration. Given C1, C2 and C3 the bacterial concentration of three samples with C1 > C2 > C3, it is DT1 < DT2 < DT3. Data from literature show how DT is a linear function of the logarithm of C0:
where the parameters A and B are dependent on the particular type of samples under test, the bacterial strains, the type of enriching medium used and so on. These parameters can be calculated by calibrating the system using a set of samples whose bacterial concentration is known and calculating the linear regression line that will be used to estimate the bacterial concentration from the measured DT.
Impedance microbiology has different advantages on the standard plate count technique to measure bacterial concentration. It is characterized by faster response time. In the case of mesophilic bacteria, the response time range from 2 – 3 hours for highly contaminated samples (105 - 106 cfu/ml) to over 10 hours for samples with very low bacterial concentration (less than 10 cfu/ml). As a comparison, for the same bacterial strains the Plate Count technique is characterized by response times from 48 to 72 hours.
Impedance microbiology is a method that can be easily automated and implemented as part of an industrial machine or realized as an embedded portable sensor, while plate count is a manual method that needs to be carried out in a laboratory by long trained personnel.
Instrumentation
Over the past decades different instruments (either laboratory built or commercially available) to measure bacterial concentration using impedance microbiology have been built. One of the best selling and well accepted instruments in the industry is the Bactometer by Biomerieux. The original instrument of 1984 features a multi-incubator system capable of monitoring up to 512 samples simultaneously with the ability to set 8 different incubation temperatures. Other instruments with performance comparable to the Bactometer are Malthus by Malthus Instruments Ltd (Bury, UK), RABIT by Don Whitley Scientific (Shipley, UK) and Bac Trac by Sy-Lab (Purkensdorf, Austria).
A portable embedded system for microbial concentration measurement in liquid and semi-liquid media using impedance microbiology has been recently proposed. The system is composed of a thermoregulated incubation chamber where the sample under test is stored and a controller for thermoregulation and impedance measurements.
Applications
Impedance microbiology has been extensively used in the past decades to measure the concentration of bacteria and yeasts in different type of samples, mainly for quality assurance in the food industry. Some applications are, the determination of the shelf life of pasteurized milk and the measure of total bacterial concentration in raw-milk, frozen vegetables, grain products, meat products and beer. The technique has been also used in environmental monitoring to detect the coliform concentration in water samples as well as other bacterial pathogens like E.coli present in water bodies, in the pharmaceutical industry to test the efficiency of novel antibacterial agents and the testing of final products.
References
Microbiology techniques
Microbiology
Impedance measurements | Impedance microbiology | Physics,Chemistry,Biology | 1,292 |
1,590,747 | https://en.wikipedia.org/wiki/Franck%E2%80%93Condon%20principle | The Franck-Condon principle describes the intensities of vibronic transitions, or the absorption or emission of a photon. It states that when a molecule is undergoing an electronic transition, such as ionization, the nuclear configuration of the molecule experiences no significant change.
Overview
The Franck–Condon principle has a well-established semiclassical interpretation based on the original contributions of James Franck. Electronic transitions are relatively instantaneous compared with the time scale of nuclear motions, therefore if the molecule is to move to a new vibrational level during the electronic transition, this new vibrational level must be instantaneously compatible with the nuclear positions and momenta of the vibrational level of the molecule in the originating electronic state. In the semiclassical picture of vibrations (oscillations) of a simple harmonic oscillator, the necessary conditions can occur at the turning points, where the momentum is zero.
In the quantum mechanical picture, the vibrational levels and vibrational wavefunctions are those of quantum harmonic oscillators, or of more complex approximations to the potential energy of molecules, such as the Morse potential. Figure 1 illustrates the Franck–Condon principle for vibronic transitions in a molecule with Morse-like potential energy functions in both the ground and excited electronic states. In the low temperature approximation, the molecule starts out in the v = 0 vibrational level of the ground electronic state and upon absorbing a photon of the necessary energy, makes a transition to the excited electronic state. The electron configuration of the new state may result in a shift of the equilibrium position of the nuclei constituting the molecule. In Figure 3 this shift in nuclear coordinates between the ground and the first excited state is labeled as q01. In the simplest case of a diatomic molecule the nuclear coordinates axis refers to the internuclear separation. The vibronic transition is indicated by a vertical arrow due to the assumption of constant nuclear coordinates during the transition. The probability that the molecule can end up in any particular vibrational level is proportional to the square of the (vertical) overlap of the vibrational wavefunctions of the original and final state (see Quantum mechanical formulation section below). In the electronic excited state molecules quickly relax to the lowest vibrational level of the lowest electronic excitation state (Kasha's rule), and from there can decay to the electronic ground state via photon emission. The Franck–Condon principle is applied equally to absorption and to fluorescence.
The applicability of the Franck–Condon principle in both absorption and fluorescence, along with Kasha's rule leads to an approximate mirror symmetry shown in Figure 2. The vibrational structure of molecules in a cold, sparse gas is most clearly visible due to the absence of inhomogeneous broadening of the individual transitions. Vibronic transitions are drawn in Figure 2 as narrow, equally spaced Lorentzian line shapes. Equal spacing between vibrational levels is only the case for the parabolic potential of simple harmonic oscillators, in more realistic potentials, such as those shown in Figure 1, energy spacing decreases with increasing vibrational energy. Electronic transitions to and from the lowest vibrational states are often referred to as 0–0 (zero zero) transitions and have the same energy in both absorption and fluorescence.
Development of the principle
In a report published in 1926 in Transactions of the Faraday Society, James Franck was concerned with the mechanisms of photon-induced chemical reactions. The presumed mechanism was the excitation of a molecule by a photon, followed by a collision with another molecule during the short period of excitation. The question was whether it was possible for a molecule to break into photoproducts in a single step, the absorption of a photon, and without a collision. In order for a molecule to break apart, it must acquire from the photon a vibrational energy exceeding the dissociation energy, that is, the energy to break a chemical bond. However, as was known at the time, molecules will only absorb energy corresponding to allowed quantum transitions, and there are no vibrational levels above the dissociation energy level of the potential well. High-energy photon absorption leads to a transition to a higher electronic state instead of dissociation. In examining how much vibrational energy a molecule could acquire when it is excited to a higher electronic level, and whether this vibrational energy could be enough to immediately break apart the molecule, he drew three diagrams representing the possible changes in binding energy between the lowest electronic state and higher electronic states.
James Franck recognized that changes in vibrational levels could be a consequence of the instantaneous nature of excitation to higher electronic energy levels and a new equilibrium position for the nuclear interaction potential. Edward Condon extended this insight beyond photoreactions in a 1926 Physical Review article titled "A Theory of Intensity Distribution in Band Systems". Here he formulates the semiclassical formulation in a manner quite similar to its modern form. The first joint reference to both Franck and Condon in regard to the new principle appears in the same 1926 issue of Physical Review in an article on the band structure of carbon monoxide by Raymond Birge.
Quantum mechanical formulation
Consider an electrical dipole transition from the initial vibrational state (υ) of the ground electronic level (ε), , to some vibrational state (υ′) of an excited electronic state (ε′), (see bra–ket notation). The molecular dipole operator μ is determined by the charge (−e) and locations (ri) of the electrons as well as the charges (+Zje) and locations (Rj) of the nuclei:
The probability amplitude P for the transition between these two states is given by
where and are, respectively, the overall wavefunctions of the initial and final state. The overall wavefunctions are the product of the individual vibrational (depending on spatial coordinates of the nuclei) and electronic space and spin wavefunctions:
This separation of the electronic and vibrational wavefunctions is an expression of the Born–Oppenheimer approximation and is the fundamental assumption of the Franck–Condon principle. Combining these equations leads to an expression for the probability amplitude in terms of separate electronic space, spin and vibrational contributions:
The spin-independent part of the initial integral is here approximated as a product of two integrals:
This factorization would be exact if the integral over the spatial coordinates of the electrons would not depend on the nuclear coordinates. However, in the Born–Oppenheimer approximation and do depend (parametrically) on the nuclear coordinates, so that the integral (a so-called transition dipole surface) is a function of nuclear coordinates. Since the dependence is usually rather smooth it is neglected (i.e., the assumption that the transition dipole surface is independent of nuclear coordinates, called the Condon approximation is often allowed).
The first integral after the plus sign is equal to zero because electronic wavefunctions of different states are orthogonal. Remaining is the product of three integrals. The first integral is the vibrational overlap integral, also called the Franck–Condon factor. The remaining two integrals contributing to the probability amplitude determine the electronic spatial and spin selection rules.
The Franck–Condon principle is a statement on allowed vibrational transitions between two different electronic states; other quantum mechanical selection rules may lower the probability of a transition or prohibit it altogether. Rotational selection rules have been neglected in the above derivation. Rotational contributions can be observed in the spectra of gases but are strongly suppressed in liquids and solids.
It should be clear that the quantum mechanical formulation of the Franck–Condon principle is the result of a series of approximations, principally the electrical dipole transition assumption and the Born–Oppenheimer approximation. Weaker magnetic dipole and electric quadrupole electronic transitions along with the incomplete validity of the factorization of the total wavefunction into nuclear, electronic spatial and spin wavefunctions means that the selection rules, including the Franck–Condon factor, are not strictly observed. For any given transition, the value of P is determined by all of the selection rules, however spin selection is the largest contributor, followed by electronic selection rules. The Franck–Condon factor only weakly modulates the intensity of transitions, i.e., it contributes with a factor on the order of 1 to the intensity of bands whose order of magnitude is determined by the other selection rules. The table below gives the range of extinction coefficients for the possible combinations of allowed and forbidden spin and orbital selection rules.
Franck–Condon metaphors in spectroscopy
The Franck–Condon principle, in its canonical form, applies only to changes in the vibrational levels of a molecule in the course of a change in electronic levels by either absorption or emission of a photon. The physical intuition of this principle is anchored by the idea that the nuclear coordinates of the atoms constituting the molecule do not have time to change during the very brief amount of time involved in an electronic transition. However, this physical intuition can be, and is indeed, routinely extended to interactions between light-absorbing or emitting molecules (chromophores) and their environment. Franck–Condon metaphors are appropriate because molecules often interact strongly with surrounding molecules, particularly in liquids and solids, and these interactions modify the nuclear coordinates of the chromophore in ways closely analogous to the molecular vibrations considered by the Franck–Condon principle.
Franck–Condon principle for phonons
The closest Franck–Condon analogy is due to the interaction of phonons (quanta of lattice vibrations) with the electronic transitions of chromophores embedded as impurities in the lattice. In this situation, transitions to higher electronic levels can take place when the energy of the photon corresponds to the purely electronic transition energy or to the purely electronic transition energy plus the energy of one or more lattice phonons. In the low-temperature approximation, emission is from the zero-phonon level of the excited state to the zero-phonon level of the ground state or to higher phonon levels of the ground state. Just like in the Franck–Condon principle, the probability of transitions involving phonons is determined by the overlap of the phonon wavefunctions at the initial and final energy levels. For the Franck–Condon principle applied to phonon transitions, the label of the horizontal axis of Figure 1 is replaced in Figure 6 with the configurational coordinate for a normal mode. The lattice mode potential energy in Figure 6 is represented as that of a harmonic oscillator, and the spacing between phonon levels () is determined by lattice parameters. Because the energy of single phonons is generally quite small, zero- or few-phonon transitions can only be observed at temperatures below about 40 kelvins.
See Zero-phonon line and phonon sideband for further details and references.
Franck–Condon principle in solvation
Franck–Condon considerations can also be applied to the electronic transitions of chromophores dissolved in liquids. In this use of the Franck–Condon metaphor, the vibrational levels of the chromophores, as well as interactions of the chromophores with phonons in the liquid, continue to contribute to the structure of the absorption and emission spectra, but these effects are considered separately and independently.
Consider chromophores surrounded by solvent molecules. These surrounding molecules may interact with the chromophores, particularly if the solvent molecules are polar. This association between solvent and solute is referred to as solvation and is a stabilizing interaction, that is, the solvent molecules can move and rotate until the energy of the interaction is minimized. The interaction itself involves electrostatic and van der Waals forces and can also include hydrogen bonds. Franck–Condon principles can be applied when the interactions between the chromophore and the surrounding solvent molecules are different in the ground and in the excited electronic state. This change in interaction can originate, for example, due to different dipole moments in these two states. If the chromophore starts in its ground state and is close to equilibrium with the surrounding solvent molecules and then absorbs a photon that takes it to the excited state, its interaction with the solvent will be far from equilibrium in the excited state. This effect is analogous to the original Franck–Condon principle: the electronic transition is very fast compared with the motion of nuclei—the rearrangement of solvent molecules in the case of solvation. We now speak of a vertical transition, but now the horizontal coordinate is solvent-solute interaction space. This coordinate axis is often labeled as "Solvation Coordinate" and represents, somewhat abstractly, all of the relevant dimensions of motion of all of the interacting solvent molecules.
In the original Franck–Condon principle, after the electronic transition, the molecules which end up in higher vibrational states immediately begin to relax to the lowest vibrational state. In the case of solvation, the solvent molecules will immediately try to rearrange themselves in order to minimize the interaction energy. The rate of solvent relaxation depends on the viscosity of the solvent. Assuming the solvent relaxation time is short compared with the lifetime of the electronic excited state, emission will be from the lowest solvent energy state of the excited electronic state. For small-molecule solvents such as water or methanol at ambient temperature, solvent relaxation time is on the order of some tens of picoseconds whereas chromophore excited state lifetimes range from a few picoseconds to a few nanoseconds. Immediately after the transition to the ground electronic state, the solvent molecules must also rearrange themselves to accommodate the new electronic configuration of the chromophore. Figure 7 illustrates the Franck–Condon principle applied to solvation. When the solution is illuminated by light corresponding to the electronic transition energy, some of the chromophores will move to the excited state. Within this group of chromophores there will be a statistical distribution of solvent-chromophore interaction energies, represented in the figure by a Gaussian distribution function. The solvent-chromophore interaction is drawn as a parabolic potential in both electronic states. Since the electronic transition is essentially instantaneous on the time scale of solvent motion (vertical arrow), the collection of excited state chromophores is immediately far from equilibrium. The rearrangement of the solvent molecules according to the new potential energy curve is represented by the curved arrows in Figure 7. Note that while the electronic transitions are quantized, the chromophore-solvent interaction energy is treated as a classical continuum due to the large number of molecules involved. Although emission is depicted as taking place from the minimum of the excited state chromophore-solvent interaction potential, significant emission can take place before equilibrium is reached when the viscosity of the solvent is high, or the lifetime of the excited state is short. The energy difference between absorbed and emitted photons depicted in Figure 7 is the solvation contribution to the Stokes shift.
See also
Born–Oppenheimer approximation
Molecular electronic transition
Ultraviolet-visible spectroscopy
Quantum harmonic oscillator
Morse potential
Vibronic coupling
Zero-phonon line and phonon sideband
Sudden approximation
References
Further reading
Link
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External links
Quantum chemistry
Spectroscopy
Molecular physics | Franck–Condon principle | Physics,Chemistry | 3,172 |
11,128,256 | https://en.wikipedia.org/wiki/Phyllosticta%20carpogena | Phyllosticta carpogena is a fungal plant pathogen infecting caneberries.
References
External links
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Small fruit diseases
carpogena
Fungus species | Phyllosticta carpogena | Biology | 43 |
65,501,114 | https://en.wikipedia.org/wiki/Heteroresistance | Heteroresistance is a phenotype in which a bacterial isolate contains sub-populations of cells with increased antibiotic resistance when compared with the susceptible main population. This phenomenon is known to be highly prevalent among several antibiotic classes and bacterial isolates and associated with treatment failure through the enrichment of low frequencies of resistant subpopulations in the presence of antibiotics. Heteroresistance is known to be highly unstable, meaning that the resistance sub-population can revert to susceptibility within a limited number of generations of growth in the absence of antibiotic. Regarding the instability and the transient characteristic of heteroresistance subpopulations, the detection of this subpopulation often face difficulties by the conventional minimum inhibitory concentration methods, such as Etests and disk diffusion tests. The gold standard for heteroresistance detection is population analysis profile tests (PAP-tests) which has less instances of false positive and false negative outcomes than the conventional methods making it more reliable. It is however a labour intensive and costly heteroresistance detection method making it difficult to implement in clinical microbiology laboratories. Hence, there is a significant demand for clinical microbiology laboratories to use rapid standardized methods to identify heteroresistance in pathologic specimen to prescribe a proper antibiotic treatment for patients.
Mechanisms
The enrichment of resistance sub-populations can be due to the acquisition of resistant mutations that are genetically stable but have high fitness cost or due to the enrichment of sub-population with increased copy number of resistance-conferring tandem gene amplifications. Tandem gene amplification of antibiotic resistance genes, which results in an increased gene dosage of the resistance genes, is the most common mechanism for unstable heteroresistance in Gram-negative bacteria.
Two other mechanisms conferring unstable heteroresistance, resulting in an increased gene dosage of the resistance genes, are plasmid copy number increase and transposition of the resistance genes onto cryptic plasmids which increases in copy number. However, this mechanism is considered unstable, leading to a rapid return to susceptibility when antibiotics are not present.
References
Bacteria | Heteroresistance | Biology | 444 |
5,518,587 | https://en.wikipedia.org/wiki/W.%20E.%20P.%20Duncan | Wilfred Eben Pinkerton Duncan (1897 – 28 January 1977) was an important figure in the early period of the Toronto Transit Commission's history.
He was born in Glasgow, Scotland, and graduated with a B.Sc. degree in engineering from Glasgow University. He emigrated to Canada and worked from 1910 to 1914 in the construction department of the Canadian Pacific Railway. Between 1915 and 1919 he served overseas in the Great War with the Canadian Expeditionary Force and the Royal Engineers, attaining the rank of Major. After the war he worked as a construction engineer in Toronto. He joined the Toronto Transportation Commission in 1921, and served in various engineering roles. By 1945 he was the TTC's Chief Engineer, and he became General Manager, the senior staff position, in 1952. In 1959, when the senior position was split in two, he became General Manager – Subway Construction, while John G. Inglis assumed the role of General Manager - Operations. Duncan retired in 1961 but remained active as a General Consultant to the TTC until the opening of the University Subway in 1963.
He was instrumental in the growth of the system and was in charge of the TTC during the building of the Yonge Subway.
The Duncan Shops, a heavy bus maintenance facility at the TTC's Hillcrest Complex, is named in his honour.
References
TTC Coupler, September 1952 Vol 27 No 9
TTC Coupler, March 1961 Vol 36 No 3
TTC Coupler, March 1977 Vol 52 No 3
Specific
1897 births
1977 deaths
Engineers from Glasgow
Alumni of the University of Glasgow
Canadian civil engineers
Toronto Transit Commission general managers
Scottish emigrants to Canada
Royal Engineers | W. E. P. Duncan | Engineering | 330 |
11,801,835 | https://en.wikipedia.org/wiki/Kin%20recognition | Kin recognition, also called kin detection, is an organism's ability to distinguish between close genetic kin and non-kin. In evolutionary biology and psychology, such an ability is presumed to have evolved for inbreeding avoidance, though animals do not typically avoid inbreeding.
An additional adaptive function sometimes posited for kin recognition is a role in kin selection. There is debate over this, since in strict theoretical terms kin recognition is not necessary for kin selection or the cooperation associated with it. Rather, social behaviour can emerge by kin selection in the demographic conditions of 'viscous populations' with organisms interacting in their natal context, without active kin discrimination, since social participants by default typically share recent common origin. Since kin selection theory emerged, much research has been produced investigating the possible role of kin recognition mechanisms in mediating altruism. Taken as a whole, this research suggests that active powers of recognition play a negligible role in mediating social cooperation relative to less elaborate cue-based and context-based mechanisms, such as familiarity, imprinting and phenotype matching.
Because cue-based 'recognition' predominates in social mammals, outcomes are non-deterministic in relation to actual genetic kinship, instead outcomes simply reliably correlate with genetic kinship in an organism's typical conditions. A well-known human example of an inbreeding avoidance mechanism is the Westermarck effect, in which unrelated individuals who happen to spend their childhood in the same household find each other sexually unattractive. Similarly, due to the cue-based mechanisms that mediate social bonding and cooperation, unrelated individuals who grow up together in this way are also likely to demonstrate strong social and emotional ties, and enduring altruism.
Theoretical background
The English evolutionary biologist W. D. Hamilton's theory of inclusive fitness, and the related theory of kin selection, were formalized in the 1960s and 1970s to explain the evolution of social behaviours. Hamilton's early papers, as well as giving a mathematical account of the selection pressure, discussed possible implications and behavioural manifestations. Hamilton considered potential roles of cue-based mechanisms mediating altruism versus 'positive powers' of kin discrimination:
These two possibilities, altruism mediated via 'passive situation' or via 'sophisticated discrimination', stimulated a generation of researchers to look for evidence of any 'sophisticated' kin discrimination. However, Hamilton later (1987) developed his thinking to consider that "an innate kin recognition adaptation" was unlikely to play a role in mediating altruistic behaviours:
The implication that the inclusive fitness criterion can be met by mediating mechanisms of cooperative behaviour that are context and location-based has been clarified by recent work by West et al.:
For a recent review of the debates around kin recognition and their role in the wider debates about how to interpret inclusive fitness theory, including its compatibility with ethnographic data on human kinship, see Holland (2012).
Criticism
Leading inclusive fitness theorists such as Alan Grafen have argued that the whole research program around kin recognition is somewhat misguided:
Others have cast similar doubts over the enterprise:
Experimental evidence
Kin recognition is a behavioral adaptation noted in many species but proximate level mechanisms are not well documented. Recent studies have shown that kin recognition can result from a multitude of sensory input. Jill Mateo notes that there are three components prominent in kin recognition. First, "production of unique phenotypic cues or labels". Second, "perception of these labels and the degree of correspondence of these labels with a 'recognition template'", and finally the recognition of the phenotypes should lead to "action taken by the animal as a function of the perceived similarity between its template and an encountered phenotype".
The three components allow for several possible mechanisms of kin recognition. Sensory information gathered from visual, olfactory and auditory stimuli are the most prevalent. The Belding's ground squirrel kin produce similar odors in comparison to non-kin. Mateo notes that the squirrels spent longer investigating non-kin scents suggesting recognition of kin odor. It's also noted that Belding's ground squirrels produce at least two scents arising from dorsal and oral secretions, giving two opportunities for kin recognition. In addition, the Black Rock Skink is also able to use olfactory stimuli as a mechanism of kin recognition. Egernia saxatilis have been found to discriminate kin from non-kin based on scent. Egernia striolata also use some form of scent, most likely through skin secretions. However, Black Rock Skinks discriminate based on familiarity rather than genotypic similarity. Juvenile E. saxatilis can recognize the difference between the scent of adults from their own family group and unrelated adults. Black Rock Skink recognize their family groups based on prior association and not how genetically related the other lizards are to themselves. Auditory distinctions have been noted among avian species. Long-tailed tits (Aegithalos caudatus) are capable of discriminating kin and non-kin based on contact calls. Distinguishing calls are often learned from adults during the nestling period. Studies suggest that the bald-faced hornet, Dolichovespula maculata, can recognize nest mates by their cuticular hydrocarbon profile, which produces a distinct smell.
Kin recognition in some species may also be mediated by immunogenetic similarity of the major histocompatibility complex (MHC). For a discussion of the interaction of these social and biological kin recognition factors see Lieberman, Tooby, and Cosmides (2007). Some have suggested that, as applied to humans, this nature-nurture interactionist perspective allows a synthesis between theories and evidence of social bonding and cooperation across the fields of evolutionary biology, psychology (attachment theory) and cultural anthropology (nurture kinship).
A study has shown that humans are about as genetically equivalent to their friends as they are their fourth cousins.
In Plants
Kin recognition is an adaptive behavior observed in living beings to prevent inbreeding, and increase fitness of populations, individuals and genes. Kin recognition is the key to successful reciprocal altruism, a behavior that increases reproductive success of both organisms involved. Reciprocal altruism as a product of kin recognition has been observed and studied in many animals, and more recently, plants. Due to the nature of plant reproduction and growth, plants are more likely than animals to live in close proximity to family members, and therefore stand to gain more from the ability to differentiate kin from strangers.
In recent years, botanists have been conducting studies to determine which plant species can recognize kin, and discover the responses of plants to neighboring kin. Murphy and Dudley (2009) shows that Impatiens pallida has the ability to recognize individuals closely related to them and those not related to them. The physiological response to this recognition is increasingly interesting. I. pallida responds to kin by increasing branchiness and stem elongation, to prevent shading relatives, and responds to strangers by increasing leaf to root allocation, as a form of competition.
Root allocation has been a very common trait shown through research in plants. Limited amounts of biomass can cause trade-offs among the construction of leaves, stems, and roots overall. But, in plants that recognize kin, the movement of resources in the plant has been shown to be affected by proximity to related individuals. It is well documented that roots can emit volatile compounds in the soil and that interactions also occur below-ground between plant roots and soil organisms. This has mainly focused on organisms in the kingdom Animalia, however.
Regarding this, root systems are known to exchange carbon and defense related molecular signals via connected mycorrhizal networks. For instance, it has been demonstrated that tobacco plants can detect the volatile chemical ethylene in order to form a “shade-avoidance phenotype.” Barley plants were also shown to allocate biomass to their roots when exposed to chemical signals from members of the same species, showing that, if they can recognize those signals for competition, recognition of kin in the plant could be likely via a similar chemical response.
Similarly, Bhatt et al. (2010) show that Cakile edentula, the American sea rocket, has the ability to allocate more energy to root growth, and competition, in response to growing next to a stranger, and allocates less energy to root growth when planted next to a sibling. This reduces competition between siblings and increases fitness of relatives growing next to each other, while still allowing competition between non-relative plants.
Little is known about the mechanisms involved in kin recognition. They most likely vary between species as well as within species. A study by Bierdrzycki et al. (2010) shows that root secretions are necessary for Arabidopsis thaliana to recognize kin vs. strangers, but not necessary to recognize self vs. non-self roots. This study was performed using secretion inhibitors, which disabled the mechanism responsible for kin recognition in this species, and showed similar growth patterns to Bhatt et al., (2010) and Murphy and Dudley (2009) in control groups. The most interesting result of this study was that inhibiting root secretions did not reduce the ability of Arabidopsis to recognize their own roots, which implicates a separate mechanism for self/non-self recognition than that for kin/stranger recognition.
While this mechanism in the roots responds to exudates and involves competition over resources like nitrogen and phosphorus, another mechanism has been recently proposed, which involves competition over light, in which kin recognition takes place in leaves. In their 2014 study, Crepy and Casal conducted multiple experiments on different accessions of A. thaliana. These experiments showed that Arabidopsis accessions have distinct R:FR and blue light signatures, and that these signatures can be detected by photoreceptors, which allows the plant to recognize its neighbor as a relative or non-relative. Not much is known about the pathway that Arabidopsis uses to associate these light patterns with kin, however, researchers ascertained that photoreceptors phyB, cry 1, cry 2, phot1, and phot2 are involved in the process by performing a series of experiments with knock-out mutants. Researchers also concluded that the auxin-synthesis gene TAA1 is involved in the process, downstream of the photoreceptors, by performing a similar experiments using Sav3 knock-out mutants. This mechanism leads to altered leaf direction to prevent shading of related neighbors and to reduce competition for sunlight.
Inbreeding avoidance
When mice inbreed with close relatives in their natural habitat, there is a significant detrimental effect on progeny survival. Since inbreeding can be detrimental, it tends to be avoided by many species. In the house mouse, the major urinary protein (MUP) gene cluster provides a highly polymorphic scent signal of genetic identity that appears to underlie kin recognition and inbreeding avoidance. Thus there are fewer matings between mice sharing MUP haplotypes than would be expected if there were random mating. Another mechanism for avoiding inbreeding is evident when a female house mouse mates with multiple males. In such a case, there appears to be egg-driven sperm selection against sperm from related males.
In toads, male advertisement vocalizations may serve as cues by which females recognize their kin and thus avoid inbreeding.
In dioecious plants, the stigma may receive pollen from several different potential donors. As multiple pollen tubes from the different donors grow through the stigma to reach the ovary, the receiving maternal plant may carry out pollen selection favoring pollen from less related donor plants. Thus, kin recognition at the level of the pollen tube apparently leads to post-pollination selection to avoid inbreeding depression. Also, seeds may be aborted selectively depending on donor–recipient relatedness.
See also
Attachment theory
Inclusive fitness
Kin selection
Nurture kinship
References
Evolutionary biology
Ethology
Kinship and descent
Selection
Organisms by adaptation | Kin recognition | Biology | 2,447 |
515,896 | https://en.wikipedia.org/wiki/Octagon%20house | Octagon houses are eight-sided houses that were popular in the United States and Canada mostly in the 1850s. They are characterized by an octagonal (eight-sided) plan and often feature a flat roof and a veranda that circles the house. Their unusual shape and appearance, quite different from the ornate pitched-roof houses typical of the period, can generally be traced to the influence of amateur architect and lifestyle pundit Orson Squire Fowler. Although there are other octagonal houses worldwide, the term octagon house usually refers to octagonal houses built in North America during this period, and up to the early 1900s.
History
Early examples, before Fowler:
Poplar Forest, Thomas Jefferson's private retreat and plantation house near Lynchburg, Virginia.
William Thornton's John Tayloe III House, more commonly called The Octagon House in Washington, D.C. After the White House was burned by the British during the War of 1812, President James Madison stayed in the Octagon House, and it was here that the Treaty of Ghent (ending the War of 1812) was signed. It is now the headquarters of the American Institute of Architects. While known as "The Octagon", it is worth noting that this particular building is not actually octagonal.
Both houses are large brick buildings in the classical tradition. They may be seen as precursors, but are somewhat different from the Victorian octagon houses which are essentially domestic structures.
Orson Squire Fowler
The leading proponent of octagonal houses was Orson Squire Fowler. Fowler was America's foremost lecturer and writer on phrenology, the pseudoscience of defining an individual's characteristics by the contours of the skull. In the middle of the 19th century, Fowler made his mark on American architecture when he touted the advantages of octagonal homes over rectangular and square structures in his widely publicized book, The Octagon House: A Home For All, or A New, Cheap, Convenient, and Superior Mode of Building, printed in the year 1848. As a result of this popular and influential publication, a few thousand octagonal houses were erected in the United States, mostly in the Midwest, the East Coast and in nearby parts of Canada.
Fowler was not a professional architect.
Advantages of the octagon plan
According to Fowler, an octagon house was cheaper to build, allowed for additional living space, received more natural light, was easier to heat, and remained cooler in the summer. These benefits all derive from the geometry of an octagon: the shape encloses space efficiently, minimizing external surface area and consequently heat loss and gain, building costs etc. A circle is the most efficient shape, but difficult to build and awkward to furnish, so an octagon is a sensible approximation. Victorian builders were used to building 135° corners, as in the typical bay window, and could easily adapt to an octagonal plan.
Design principles
Fowler's The Octagon House is sometimes incorrectly referred to as a pattern book but the popularity of the book lies in the way Fowler suggested some general principles, and encouraged readers to invent the details for themselves. Only a few examples are offered, and apart from plans, the book has only two illustrations.
Fowler first shows some methods of subdividing an octagonal floor plan. Next is Howland's octagonal plan, a small house designed by 'Messrs. Morgan and Brothers, architects' which is similar to the Norrish House illustrated below. There follows A description of the author's own residence, now known as Fowler's Folly, at Fishkill, of which more below. Finally, A superior plan for a good sized house, which is a development of the Fishkill plans, apparently proposed by his engraver. The main feature of his plans is a desire to eliminate unnecessary circulation space, sometimes to the point that the main staircase is inconvenient, and the external veranda is the best way to get around the house.
Other design proposals include:
Flat roof to collect rainwater, with cisterns built-in to collect and distribute the water.
Rainwater filtering, using filter beds made up of alternating layers of sand and activated charcoal.
Central heating by distributing hot air from a furnace in the basement.
Flues, air ducts and speaking tubes built into the thickness of walls.
Built examples vary greatly in how much of this influence is apparent. Although built in brick, the Watertown house featured in this article is an almost perfect embodiment of many of Fowler's ideas.
Masswall construction
Stacked board construction was recommended in the first edition of A Home for All but the third edition of Fowler's book, printed in 1853, had a new subtitle: A Home For All, or The Gravel Wall and Octagon Mode of Building, and was distinguished by Fowler's enthusiasm for concrete construction. At the time concrete construction was not widely used as Portland cement was only recently discovered by a Mr. Goodrich of Janesville, Wisconsin. Fowler knew gravel and lime were available in unlimited quantities in the prairies and saw the "gravel wall" as offering a new, cheap and durable way of building. His house at Fishkill was built using concrete. The walls were built up a few feet at a time, by pouring a mixture of gravel and lime into timber shuttering. As the concrete cured, the shuttering could be taken down and moved up to the next level.
Modern concrete is made using Portland cement, not lime, but the main difference is the universal use of steel reinforcing bars, which greatly increase the strength of the material, and make it possible to build concrete beams and floor slabs as well as walls. Fowler used large stones to reinforce corners, but he used no other reinforcement, and was therefore restricted to walls. The roof, floors and verandas are all of timber construction.
Fowler's Folly
To quote Fowler "...those studies which have eventuated in this work were instituted primarily in order to erect this very house". Construction began in 1848, the same year his book was first published, and took five years to complete. The house was large, to each side of the octagon or across, and built on a hilltop overlooking the Hudson River, where it could be seen for miles around. Fowler removed the top of the hill to create a level site and to provide material for his "gravel walls". This grand residence had four huge reception rooms which could be interconnected depending on the size of event, allegedly 60 rooms (counting small dressing rooms as well as proper rooms) and a glazed cupola rising to above ground. Fowler's favorite writing room was an internal room on the third floor, lit only from the cupola via a fanlight over the door. The house had no central staircase, so visitors entered one of the main rooms through a small lobby, while family and staff used the basement entrance. There are verandas all round the house at first-, second- and third-floor levels, linked by two outside stairs.
The financial panic of 1857 led Fowler to rent out the house, which subsequently went through a series of owners. Fowler's Folly fell into disrepair, and finally - condemned as a public hazard - it was dynamited in 1897 by Fred C. Haight, demolition engineer for the city of Fishkill.
Surviving examples
Estimates vary but hundreds of these Victorian-era homes are still standing across the United States and Canada. One estimate puts the number at 2,077. Even in their heyday, octagon houses were never mainstream.
The largest remaining octagon homes in the United States are Longwood in Natchez, Mississippi and the Octagon House in Watertown, Wisconsin. Both homes are open to the public. In Eastern Washington state one still sits where it was moved to in 1993 to Bridgeport, near the Columbia River.
Fowler was influential, but not the only proponent of octagonal houses and other structures. There are also octagonal barns, schoolhouses, churches, and in Canada, octagonal "dead houses".
Design and variations
Within the central idea of the octagonal plan, these houses show a wide variety of both construction and outward form. They range from the modest two-storey Bevis-Tucker House, to the grandiose Armour-Stiner House (both are illustrated below).
A full octagon house has eight equal sides, although slight variations in length are not unusual. In some cases the basic octagon is partially obscured by additions, either all round as at the Zelotes Holmes House, or by adding a functional wing out of sight at the rear. The House of the Seven Gables in Mayo, Florida has gables on seven sides while the eighth side is extended to the rear.
The Richard Peacon House in Key West, Florida, appears to be a full octagon from the street but the rear portion is squared off.
Fowler advocated the use of "gravel wall" construction for the walls. This was an experimental technique at the time, and although some were built that way, most octagon houses were built the same way as ordinary houses, of timber frame, brick or stone.
Planned community
A moral community headed by Henry S. Clubb tried to establish Octagon City in 1856 in Kansas.
It was intended to have an octagonal square with eight roads and octagonal farmhouses and barns.
Most settlers had left after the winter.
Examples of octagon houses
The following are examples of the 'true' octagon houses and the range of design variations to be found.
Case study: Watertown Octagon House, Wisconsin
Although one of the largest, the Watertown house is midway between the grandest and most modest surviving examples. It is well documented, has been carefully restored, and is open to the public as a museum.
History
Construction was completed 1854. The house fell into disuse and was taken over by the newly founded Watertown Historical Society, and opened to the public in 1938. It is still owned by the Society.
Construction and innovations
The plan is a octagon, with a veranda all round at first- and second-floor levels.
The house is built on stone foundations, with external walls of brickwork thick.
The central square is made up of two leaves of brickwork with a cavity, which is used for chimney flues and warm air ducting, to heat rooms without fireplaces. The double wall eliminates the need for projecting chimney breasts.
The battlement effect at the top of the cupola is actually the four chimneys.
A furnace in the basement heats water, and warm air is ducted into the twelve main rooms, i.e. those adjoining the central square.
An elegant spiral staircase links all the floors. It is self-supporting on the inside and built into the walls on the outside of the stairwell. There is also a servants' staircase.
The house has a flat roof, sloping gently towards the center.
Rainwater from the roof was collected in a reservoir at third-floor level, and overflows into a cistern next to the kitchen in the basement.
Publications regularly state the house has 57 rooms; however this includes every closet and passage. The number of habitable rooms is 29, including the octagonal room in the cupola.
Despite having 15 bedrooms there is just a single bathroom.
Architectural style
The house was inspired by Fowler's book, and is a good example of his theories put into practice. Features which are directly linked to his ideas, apart from the octagonal plan, are the central spiral staircase, symmetrical arrangement of rooms with interconnecting doors, the verandas running all round the building, and the flat roof surmounted by a cupola. In accordance with Fowler's theories, the detailing is relatively plain for the period. Openings are simply framed by moldings. The covered verandas lack excess detail, having modest turned balustrade spindles and supporting posts. The decorative effect of the house comes from the basic design features: the octagonal shape and the external verandas.
There are four generously sized rooms on each floor, nearly 18 foot square, with connecting doors all round. The subsidiary rooms are less satisfactory, being triangular. The arrangement of rooms is rigidly the same on all floors because the partition walls are of brickwork, so they must stack one above the other. The central spiral stair is compact, but leaves one side of the house without direct access to the landings, so there are bedrooms only accessible through another bedroom - in the worst case, through two other bedrooms. The drawbacks of this arrangement are again a legacy of Fowler's influence, an unwillingness to sacrifice spaciousness in the rooms to sensible circulation arrangements. Fowler's own house had external staircases and the verandas were used for circulation and access to the rooms.
Record drawings
Below are drawings of the Watertown Octagon House dated March 28, 1935, prepared by the Historic American Buildings Survey. At that time the verandas were missing, removed when they became dangerously rotten. The survey drawings are a reconstruction of the house as it was originally built.
See also
List of octagon houses
List of octagonal buildings and structures
References
Further reading
Baker, John Milnes. American House Styles: A Concise Guide. NY: W. W. Norton & Company, 2002.
Puerzer, Ellen L. The Octagon House Inventory. Eight-Square Publishing, 2011.
Rempel, John I.Building with Wood. Toronto: University of Toronto Press, 1967.
Schmidt, Carl F. The Octagon Fad. 1958.
Schmidt, Carl F. and Philip Parr. More About Octagons. 1978.
Goncalves, Eliseu. The Octagon in the Houses of Orson Fowler. Nexus Journal, vol 13, nº 2. Basel: Springer/Birkhauser, 2011.
Fowler, Orson S. with a new Introduction by Madeleine B. Stern. "The Octagon House: A Home For All" Dover Publications, 1973.
External links
Northeast Journal: Fowler's Folly, Fishkill, NY
Octagon House Inventory, by Robert Kline, a retired engineer living in Grand Rapids, MI
Oldhouseweb: Octagon House: 1850-1860
Buffalo Architecture and History: Octagon House Style
Woodchester Museum (Ontario): Octagonal houses in Canada
Ontario Architecture: Ontario Octagon Movement
The Octagon in the Houses of Orson Fowler
House styles
American architectural styles
Architecture related to utopias | Octagon house | Engineering | 2,940 |
1,299,404 | https://en.wikipedia.org/wiki/Feature%20%28machine%20learning%29 | In machine learning and pattern recognition, a feature is an individual measurable property or characteristic of a data set. Choosing informative, discriminating, and independent features is crucial to produce effective algorithms for pattern recognition, classification, and regression tasks. Features are usually numeric, but other types such as strings and graphs are used in syntactic pattern recognition, after some pre-processing step such as one-hot encoding. The concept of "features" is related to that of explanatory variables used in statistical techniques such as linear regression.
Feature types
In feature engineering, two types of features are commonly used: numerical and categorical.
Numerical features are continuous values that can be measured on a scale. Examples of numerical features include age, height, weight, and income. Numerical features can be used in machine learning algorithms directly.
Categorical features are discrete values that can be grouped into categories. Examples of categorical features include gender, color, and zip code. Categorical features typically need to be converted to numerical features before they can be used in machine learning algorithms. This can be done using a variety of techniques, such as one-hot encoding, label encoding, and ordinal encoding.
The type of feature that is used in feature engineering depends on the specific machine learning algorithm that is being used. Some machine learning algorithms, such as decision trees, can handle both numerical and categorical features. Other machine learning algorithms, such as linear regression, can only handle numerical features.
Classification
A numeric feature can be conveniently described by a feature vector. One way to achieve binary classification is using a linear predictor function (related to the perceptron) with a feature vector as input. The method consists of calculating the scalar product between the feature vector and a vector of weights, qualifying those observations whose result exceeds a threshold.
Algorithms for classification from a feature vector include nearest neighbor classification, neural networks, and statistical techniques such as Bayesian approaches.
Examples
In character recognition, features may include histograms counting the number of black pixels along horizontal and vertical directions, number of internal holes, stroke detection and many others.
In speech recognition, features for recognizing phonemes can include noise ratios, length of sounds, relative power, filter matches and many others.
In spam detection algorithms, features may include the presence or absence of certain email headers,
the email structure, the language, the frequency of specific terms, the grammatical correctness of the text.
In computer vision, there are a large number of possible features, such as edges and objects.
Feature vectors
In pattern recognition and machine learning, a feature vector is an n-dimensional vector of numerical features that represent some object. Many algorithms in machine learning require a numerical representation of objects, since such representations facilitate processing and statistical analysis. When representing images, the feature values might correspond to the pixels of an image, while when representing texts the features might be the frequencies of occurrence of textual terms. Feature vectors are equivalent to the vectors of explanatory variables used in statistical procedures such as linear regression. Feature vectors are often combined with weights using a dot product in order to construct a linear predictor function that is used to determine a score for making a prediction.
The vector space associated with these vectors is often called the feature space. In order to reduce the dimensionality of the feature space, a number of dimensionality reduction techniques can be employed.
Higher-level features can be obtained from already available features and added to the feature vector; for example, for the study of diseases the feature 'Age' is useful and is defined as Age = 'Year of death' minus 'Year of birth' . This process is referred to as feature construction. Feature construction is the application of a set of constructive operators to a set of existing features resulting in construction of new features. Examples of such constructive operators include checking for the equality conditions {=, ≠}, the arithmetic operators {+,−,×, /}, the array operators {max(S), min(S), average(S)} as well as other more sophisticated operators, for example count(S,C) that counts the number of features in the feature vector S satisfying some condition C or, for example, distances to other recognition classes generalized by some accepting device. Feature construction has long been considered a powerful tool for increasing both accuracy and understanding of structure, particularly in high-dimensional problems. Applications include studies of disease and emotion recognition from speech.
Selection and extraction
The initial set of raw features can be redundant and large enough that estimation and optimization is made difficult or ineffective. Therefore, a preliminary step in many applications of machine learning and pattern recognition consists of selecting a subset of features, or constructing a new and reduced set of features to facilitate learning, and to improve generalization and interpretability.
Extracting or selecting features is a combination of art and science; developing systems to do so is known as feature engineering. It requires the experimentation of multiple possibilities and the combination of automated techniques with the intuition and knowledge of the domain expert. Automating this process is feature learning, where a machine not only uses features for learning, but learns the features itself.
See also
Covariate
Dimensionality reduction
Feature engineering
Hashing trick
Statistical classification
Explainable artificial intelligence
References
Data mining
Machine learning
Pattern recognition | Feature (machine learning) | Engineering | 1,070 |
53,296 | https://en.wikipedia.org/wiki/Niels%20Bohr%20Institute | The Niels Bohr Institute () is a research institute of the University of Copenhagen. The research of the institute spans astronomy, geophysics, nanotechnology, particle physics, quantum mechanics, and biophysics.
Overview
The institute was founded in 1921, as the Institute for Theoretical Physics of the University of Copenhagen, by the Danish theoretical physicist Niels Bohr, who had been on the staff of the University of Copenhagen since 1914, and who had been lobbying for its creation since his appointment as professor in 1916. On the 80th anniversary of Niels Bohr's birth – October 7, 1965 – the Institute officially became the Niels Bohr Institute. Much of its original funding came from the charitable foundation of the Carlsberg brewery, and later from the Rockefeller Foundation.
During the 1920s, and 1930s, the institute was the center of the developing disciplines of atomic physics and quantum physics. Physicists from across Europe (and sometimes further abroad) often visited the institute to confer with Bohr on new theories and discoveries. The Copenhagen interpretation of quantum mechanics is named after work done at the institute during this time.
Following his father's death in 1962, Aage Bohr succeeded him as director of the Niels Bohr Institute, a position he held until 1970. He remained active there until he retired in 1992.
On January 1, 1993, the institute was merged with the Astronomic Observatory, the Ørsted Laboratory and the Geophysical Institute. The new resulting institute retained the name Niels Bohr Institute.
Research sections
The research at the Niels Bohr Institute spans Astronomy, Geophysics, Nanophysics, Particles Physics, Quantum Physics and Biophysics.
Research at the institute is based on observations, fieldwork, laboratory experiments and theoretical models for the purpose of understanding basic laws and complex truths on this world. The Institute has a broad network of scientific cooperation, and a lively exchange of collaborators and guests with leading international research groups.
Astrophysics
A broad spectrum of astronomy and astrophysics is researched at the Niels Bohr Institute – everything from the visible Universe such as planets, stars and galaxies – to the invisible universe and the presence of dark energy and dark matter.
The NBI astrophysicists participate in many international projects and have access to modern telescopes and satellites via, e.g. Denmark’s membership of the European Southern Observatory (ESO) and the European Space Agency (ESA), and to state-of-the-art supercomputers.
Biocomplexity and Biophysics
Biocomplexity is a cutting-edge area of research between physics and biology. By using the principles and methods of physics one can explore the living nature and biological phenomena.
Researchers at BioComplexity continuously explore the diversity of complex phenomena in biological, physical and social systems, including pattern formation, complex and chaotic dynamics, fluid dynamics, game theory, networks and econophysics.
Physics approaches are used to suggest and perform experiments and models of living systems. The systems range from proteins and gene regulation to larger-scale collective spatiotemporal structure formation. The research at the institute is often performed as a collaboration between physicists, biologists, medical doctors, and nanoscientists.
Condensed Matter Physics
Condensed matter physics is concerned with the understanding of the physical properties of solids and liquids, both naturally occurring and artificially produced.
Condensed matter physics is the foundation for many every-day technologies, ranging from hardening of steel to integrated microchips. Modern research in condensed matter physics takes place in both large scale x-ray and neutron scattering facilities, as well as in locally based laboratories, where quantum phenomena are being explored at temperatures near absolute zero. There is a vivid exchange between condensed matter and neighboring research areas, including biophysics, nanoscience, chemistry, optics, and quantum information.
Experimental Particle Physics
How was the universe created, which inflation scenario played out in the first split second, what happened during the quark-gluon plasma era? What is the source of the mass spectrum of fundamental particles of matter and forces? These are some of the questions particle physicists are looking for answers to.
The Particle Physicists work with the build up of matter in the early universe. They are searching for an explanation as to what the universe's smallest components were composed of in the first milliseconds after the Big Bang 14 billion years ago and what forces held them together.
Physics of Ice, Climate and Earth
The section for the Physics of Ice, Climate and Earth at the Niels Bohr Institute studies the elements of the Earth and climate system – the atmosphere, oceans, ice sheets and glaciers, sea ice, and the solid Earth itself – and the interactions between them.
Quantum Optics and Photonics
The Quantum Optics section conducts experimental and theoretical research in Quantum Optics, in particular, in Quantum Information Processing, Quantum Sensors , and Quantum Technologies.
We use photons, from optics to microwaves interacting with a wide variety of quantum matter, such as quantum dots, single atoms, atomic ensembles and mechanical oscillators.
The overarching theme is generation and manipulation of non-classical entangled states for quantum simulation, sensing and communication. The research directions span from fundamental research to device engineering.
Theoretical high energy, astroparticle and gravitational physics
The Theoretical high energy, astroparticle and gravitational physics at the Niels Bohr Institute is involved in a wide scope of research activities centered around quantum theories of gauge fields, gravity and astrophysics.
Research areas include scattering amplitudes, effective field theory, black holes, holography, lattice simulations, quantum gravity, integrability, astroparticle physics, and cosmology.
Research Centres
Cosmic Dawn
The Cosmic Dawn Center is an Astronomy/Cosmology research center, founded as a collaboration between the University of Copenhagen and DTU Space of the Danish Technical University (DTU). The center is led by center director and NBI Professor Sune Toft and center co-director Thomas Greve, Professor at DTU and UCL. The main objective of the center is to investigate the period known as the Cosmic Dawn (the transition period following the Cosmic Dark Ages), i.e. the reionization of the Universe and the formation of the first galaxies, through observations as well as through theory and simulations.
Goals
Research conducted at the center is focused on the specific period in the history of the Universe known as the Cosmic Dawn. This largely unexplored period, 300-600 million years after the Big Bang is when the first stars, black holes, and galaxies are believed to have formed. Many of the observations used by the center originate from the Atacama Large Millimeter Array (ALMA), one of the more powerful telescopes in the world. In the future, the center aims to mainly use the James Webb Space Telescope and the Euclid Telescope of the European Space Agency (ESA). DAWN scientists were instrumental in the construction of three instruments (NIRSpec, MIRI and NIRISS) for the project, and will be involved in the analysis of the first data from the telescope.
Published research
As of April 18, 2020, DAWN authors have published at least 187 refereed papers garnering 1602 citations, which, among others, can be found at the NASA/ADS library.
Observation of inverse Compton emission from a long γ-ray burst:
Identification of strontium in the merger of two neutron stars:
Signatures of a jet cocoon in early spectra of a supernova associated with a γ-ray burst:
Stellar Velocity Dispersion of a Massive Quenching Galaxy at z = 4.01:
Medal of Honour
in 2010, the year of the 125th anniversary of the birth of Niels Bohr, the institute established the Niels Bohr Institute Medal of Honour. It is an annual award for "a particularly outstanding researcher who is working in the spirit of Niels Bohr: International cooperation and the exchange of knowledge".
The medal is made by Danish sculptor Rikke Raben for the Niels Bohr Institute. On the front is a portrait of Niels Bohr, the atom sign and stars. The illustration on the back is inspired by a quote from Bohr: What is it that we human beings ultimately depend on? We depend on our words. We are suspended in language. Our task is to communicate experience and ideas to others.
On the back of the medal: Unity of Knowledge – the title of a lecture given by Bohr at Columbia University in 1954. Nosce te ipsum is Latin and means "know thyself". This quote originates from the Oracle of Delphi, in the Temple of Apollo in Greece.
Recipients:
2010: Leo Kadanoff
2011: Andre Geim
2012: Juan Ignacio Cirac Sasturain
2013: Fabiola Gianotti
2014: Glaciologist Jérôme Chappellaz
2015: Astrophysicist Brian Schmidt
2016: Gerard 't Hooft
2017:
2019: David R. Nelson
2020: Paul J. Steinhardt
2021: Jun Ye
See also
Niels Bohr
Nano-Science Center (Copenhagen University)
Institute for Theoretical Physics (disambiguation)
Center for Theoretical Physics (disambiguation)
List of physics awards
References
External links
Niels Bohr Institute (en), Niels Bohr Institutet (dk)
Dark Cosmology Centre (en)
Discovery Center (en)
(DAWN)
DTU Space
University of Copenhagen
Research institutes in Denmark
Physics research institutes
Niels Bohr
Physics awards
Research institutes established in 1921
1921 establishments in Denmark
Theoretical physics institutes | Niels Bohr Institute | Physics,Technology | 1,940 |
10,696,110 | https://en.wikipedia.org/wiki/Supralateral%20arc | A supralateral arc is a comparatively rare member of the halo family which in its complete form appears as a large, faintly rainbow-colored band in a wide arc above the sun and appearing to encircle it, at about twice the distance as the familiar 22° halo. In reality, however, the supralateral arc does not form a circle and never reaches below the sun. When present, the supralateral arc touches the (much more common) circumzenithal arc from below. As in all colored halos, the arc has its red side directed towards the sun, its blue part away from it.
Formation
Supralateral arcs form when sun light enters horizontally oriented, rod-shaped hexagonal ice crystals through a hexagonal base and exits through one of the prism sides. Supralateral arcs occur about once a year.
Confusion with the 46° halo
Due to its apparent circular shape and nearly identical location in the sky, the supralateral arc is often mistaken for the 46° halo, which does form a complete circle around the sun at approximately the same distance, but which is much rarer and fainter. Distinguishing between the two phenomena can be difficult, requiring the combination of several subtle indicators for proper identification.
In contrast to the static 46° halo, the shape of a supralateral arc varies with the elevation of the sun. Before the sun reaches 15°, the bases of the arc touch the lateral (oriented sidewise) sides of the 46° halo. As the sun rises from 15° to 27°, the supralateral arc almost overlaps the upper half of the 46° halo, which is why many reported observations of the latter most likely are observations of the former. As the sun goes from 27° to 32°, the apex of the arc touches the circumzenithal arc centered on zenith (as does the 46° halo when the sun is located between 15° and 27°). In addition, the supralateral arc is always located above the parhelic circle (the arc located below it is the infralateral arc), and is never perfectly circular.
Arguably the best way of distinguishing the halo from the arc is to carefully study the difference in colour and brightness. The 46° halo is six times fainter than the 22° halo and generally white with a possible red inner edge. The supralateral arc, in contrast, can even be confused with the rainbow with clear blue and green strokes.
Gallery
See also
Infralateral arc
Parry arc
Lowitz arc
References
External links
Atmospheric Optics - Supralateral & infralateral arcs - including HaloSim computer simulations and crystal illustrations.
Paraselene.de - Gallery of images from March 2002
Paraselene.de - Gallery of images from December 2007
Atmospheric optical phenomena | Supralateral arc | Physics | 592 |
3,167,913 | https://en.wikipedia.org/wiki/Smoluchowski%20coagulation%20equation | In statistical physics, the Smoluchowski coagulation equation is a population balance equation introduced by Marian Smoluchowski in a seminal 1916 publication, describing the time evolution of the number density of particles as they coagulate (in this context "clumping together") to size x at time t.
Simultaneous coagulation (or aggregation) is encountered in processes involving polymerization, coalescence of aerosols, emulsication, flocculation.
Equation
The distribution of particle size changes in time according to the interrelation of all particles of the system. Therefore, the Smoluchowski coagulation equation is an integrodifferential equation of the particle-size distribution. In the case when the sizes of the coagulated particles are continuous variables, the equation involves an integral:
If dy is interpreted as a discrete measure, i.e. when particles join in discrete sizes, then the discrete form of the equation is a summation:
There exists a unique solution for a chosen kernel function.
Coagulation kernel
The operator, K, is known as the coagulation kernel and describes the rate at which particles of size coagulate with particles of size . Analytic solutions to the equation exist when the kernel takes one of three simple forms:
known as the constant, additive, and multiplicative kernels respectively. For the case it could be mathematically proven that the solution of Smoluchowski coagulation equations have asymptotically the dynamic scaling property. This self-similar behaviour is closely related to scale invariance which can be a characteristic feature of a phase transition.
However, in most practical applications the kernel takes on a significantly more complex form. For example, the free-molecular kernel which describes collisions in a dilute gas-phase system,
Some coagulation kernels account for a specific fractal dimension of the clusters, as in the diffusion-limited aggregation:
or Reaction-limited aggregation:
where are fractal dimensions of the clusters, is the Boltzmann constant, is the temperature, is the Fuchs stability ratio, is the continuous phase viscosity, and is the exponent of the product kernel, usually considered a fitting parameter. For cloud, the kernel for coagulation of cloud particles are usually expressed as:
where and are the radius and fall speed of the cloud particles usually expressed using power law.
Generally the coagulation equations that result from such physically realistic kernels are not solvable, and as such, it is necessary to appeal to numerical methods. Most of deterministic methods can be used when there is only one particle property (x) of interest, the two principal ones being the method of moments and sectional methods. In the multi-variate case, however, when two or more properties (such as size, shape, composition, etc.) are introduced, one has to seek special approximation methods that suffer less from curse of dimensionality. Approximation based on Gaussian radial basis functions has been successfully applied to the coagulation equation in more than one dimension.
When the accuracy of the solution is not of primary importance, stochastic particle (Monte Carlo) methods are an attractive alternative. Through this method, to compute the coagulation rates for different coagulation events, the simulation entries are virtualized to be equally weighted. The accuracy of this transformation can be adjusted such that just those coagulation events are considered while keeping the number of simulation entries constant.
Condensation-driven aggregation
In addition to aggregation, particles may also grow in size by condensation, deposition or by
accretion. Hassan and Hassan recently proposed a condensation-driven aggregation (CDA) model in which aggregating particles keep growing continuously between merging upon collision. The CDA model can be understood by the following reaction scheme
where denotes the aggregate of size at time and is the elapsed time. This reaction scheme can be described by the following generalized Smoluchowski equation
Considering that a particle of size grows due to condensation between collision time equal to inverse of by an amount i.e.
One can solve the generalized Smoluchowski equation for constant kernel to give
which exhibits dynamic scaling.
A simple fractal analysis reveals that the condensation-driven aggregation can be best described as a fractal of dimension
The th moment of is always a conserved quantity which is responsible for fixing all the exponents of the dynamic scaling. Such conservation law has also been found in Cantor set too.
See also
Einstein–Smoluchowski relation
Flocculation
Smoluchowski factor
Williams spray equation
DLVO theory
References
Differential equations
Statistical mechanics | Smoluchowski coagulation equation | Physics,Mathematics | 949 |
2,668,907 | https://en.wikipedia.org/wiki/Tau%20Serpentis | The Bayer designation Tau Serpentis (τ Ser / τ Serpentis) is shared by a collection of eight stars, τ1 Serpentis through τ8 Serpentis, in the head of the constellation Serpens. They are distributed within a box of size 40 minutes in right ascension by 3.5° in declination. They are numbered by increasing right ascension:
Tau1 Serpentis, also designated 9 Serpentis or HD 137471.
Tau2 Serpentis, also designated 12 Serpentis or HD 138527.
Tau3 Serpentis, also designated 15 Serpentis or HD 139074.
Tau4 Serpentis, also designated 17 Serpentis or HD 139216.
Tau5 Serpentis, also designated 18 Serpentis or HD 139225.
Tau6 Serpentis, also designated 19 Serpentis or HD 140027.
Tau7 Serpentis, also designated 22 Serpentis or HD 140232.
Tau8 Serpentis, also designated 26 Serpentis or HD 140729.
Serpentis, Tau
Serpens | Tau Serpentis | Astronomy | 211 |
77,654,076 | https://en.wikipedia.org/wiki/Gamal%20Refai-Ahmed | Gamal Refai-Ahmed is an Egyptian-Canadian-American engineer and technical executive known for his substantial contributions to thermal management, silicon architecture, and advanced packaging technologies. His work has had a significant impact on high-performance computing (HPC), artificial intelligence (AI), and microelectromechanical systems (MEMS). Refai Ahmed currently resides in the United States.
Early life and education
Refai Ahmed was born in Alexandria, Egypt. He completed his bachelor's degree in mechanical engineering from Alexandria University's Faculty of Engineering in 1985. He furthered his education in Canada, where he obtained a master's degree from the University of Waterloo in 1990, followed by a Ph.D. in mechanical engineering from the same institution in 1994. His doctoral research focused on the thermal management of electronics packaging.
Career
Refai Ahmed's career spans over three decades, during which he has held senior technical positions at several leading technology companies, including AMD, GE, Cisco, and Nortel.
Nortel (1996–1999): He served as a senior member of the scientific staff, focusing on thermal tools and modeling for power supplies.
Cisco Systems Canada (2000–2001): Refai Ahmed was a thermal technical leader, developing thermal architectures for new routers and optical shelves.
Advanced Micro Devices (2006–2011): In his role as a fellow and thermal domain expert, he defined technology directions for the Platform Products Group and developed thermal management architectures for graphics, multimedia, mobile, and digital TV applications.
PreQual Technologies Corp (2011–2013): He served as chief scientist and founder, defining technology directions for platform development and spearheading innovations in LED printing and green energy systems.
GE Global Research Center (2013–2014): As a senior technology architect, Refai Ahmed led the development of thermal management technology for GE's Intelligent Platform Controlling Systems and Healthcare Mobile Systems.
AMD and Xilinx (2015-Present): Refai Ahmed serves as a senior fellow and chief architect at AMD. He has played a pivotal role in developing advanced silicon power thermo-mechanical architectures, enhancing thermal management and packaging technologies for Xilinx products across telecom, data centers, and automotive sectors.
Honors and recognitions
Refai Ahmed has received numerous awards and honors throughout his distinguished career:
2004: Elected as a Fellow of ASME, acknowledging his contributions to mechanical engineering and thermal management.
2010: Received the Calvin W. Rice Lecture from the American Society of Mechanical Engineers (ASME).
2010: Elected as a Fellow of the Canadian Academy of Engineering (CAE).
2014: Received the IEEE Canada R.H. Tanner Industrial Leadership Silver Medal Award.
2017: Named Innovation Leader of the Year by the Integrated Electronics Engineering Center (IEEC) at Binghamton State University.
2019: Awarded the Presidential Medal from Binghamton University of New York for Innovation Leadership and Academic Contributions.
2020: Elected as a Fellow of the Engineering Institute of Canada (EIC).
2020: Elevated to IEEE Fellow, recognizing his contributions to electronic packaging.
2024: Elected as a Member of the National Academy of Engineering (NAE).
2024: Recipient of Alumni Achievement Medal for Professional Achievement from Faculty of Engineering, University of Waterloo.
Publications and Patents
Dr. Refai Ahmed has published extensively on topics related to thermal management, packaging technology, and high-performance computing. His recent publications have appeared in IEEE, ASME, and other leading journals. He holds over 160 patents in semiconductor packaging, thermal management solutions, and electronic cooling technologies.
Professional Affiliations
Dr. Refai Ahmed is actively involved in professional societies and committees. He has served on the IEEE Fellow Committee, the Executive Member of the High-Density Packaging (HIR) Technical Working Group, and the Advisory Board of the NSF E2S Center. Additionally, he has been an associate editor for several journals, including the *Journal of Thermal Science and Engineering Applications* and the *Journal of Electronics Packaging*.
References
1963 births
Living people
American people of Egyptian descent
Canadian people of Egyptian descent
People from Alexandria
Electrical engineers | Gamal Refai-Ahmed | Engineering | 833 |
43,236,771 | https://en.wikipedia.org/wiki/Suslin%20algebra | In mathematics, a Suslin algebra is a Boolean algebra that is complete, atomless, countably distributive, and satisfies the countable chain condition. They are named after Mikhail Yakovlevich Suslin.
The existence of Suslin algebras is independent of the axioms of ZFC, and is equivalent to the existence of Suslin trees or Suslin lines.
See also
Andrei Suslin
References
Boolean algebra
Forcing (mathematics)
Independence results | Suslin algebra | Mathematics | 98 |
25,301,918 | https://en.wikipedia.org/wiki/Odontella%20%28diatom%29 | Odontella is a genus of marine diatoms. Some sources place it in the family Triceratiaceae, others in the family Odontellaceae. It contains the following species:
Odontella aurita (Lyngbye) C. A. Agardh
Odontella calamus (Brun & Tempère) H. J. Schrader
Odontella cornuta (J. Brun) H. J. Schrader
Odontella granulata (Roper) R. Ross
Odontella hastata (Greville) J. Fenner ex D. M. Williams
Odontella litigiosa (Van Heurck) Hoban
Odontella longicruris (Greville) Hoban
Odontella mobiliensis (J. W. Bailey) Grunow
Odontella regia (Schultze) Simonsen
Odontella rhombus
Odontella septentrionalis H. J. Schrader
Odontella sinensis (Greville) Grunow
Odontella weissflogii (Janisch) Grunow
References
Diatom genera
Diatoms | Odontella (diatom) | Biology | 251 |
742,345 | https://en.wikipedia.org/wiki/Hacienda%20%28resort%29 | The Hacienda was a hotel and casino on the Las Vegas Strip in Paradise, Nevada, that operated from 1956 to 1996. It was opened by Warren Bayley, who owned other Hacienda properties in California as well. Bayley opened the hotel portion in June 1956, although the opening of the casino was delayed as the Nevada Gaming Control Board objected to his choice of casino manager, Jake Kozloff. The casino portion eventually opened on October 17, 1956. The $6 million property had 266 rooms and the largest pool on the Las Vegas Strip. Like its sister properties in California, the resort included a neon sign that depicted a cowboy riding a palomino horse.
The Hacienda was built at the south end of the Strip, making it the first resort to be seen by tourists driving up from California. The Hacienda was located by itself at the time, a distance away from other resorts. Because of its location, most guests did not bother to visit the other resorts. The Hacienda was the first Las Vegas resort to target a family clientele, and until 1962, it operated a plane service to fly in guests from out of state.
When Bayley died in 1964, his wife Judy Bayley took over the Hacienda. At the time, she was the only female casino owner in Las Vegas. She died in 1971, and the resort was sold to a group of investors, who added an RV park for guests. The Hacienda was sold entirely to Paul Lowden, a part owner, in 1977. The Hacienda hosted several ice-skating shows starting in the 1970s, and would later host Lance Burton in a magic show that ran for five years. The Little Church of the West was relocated onto the Hacienda property in 1979, and 11-story hotel towers were added in 1980 and 1991, for a total of 1,137 rooms.
Circus Circus Enterprises purchased the Hacienda in 1995, with plans to build a new resort in its place. The Hacienda closed on December 1, 1996, and the hotel was imploded at the end of the month as part of a televised New Year's Eve special. The last portions of the hotel were demolished in January 1997. Circus Circus Enterprises opened the Mandalay Bay resort on the site in 1999, and the Hacienda name was licensed to another property, the Hacienda Hotel and Casino, near Boulder City, Nevada. The neon horse sign was preserved and put on display in downtown Las Vegas.
History
Construction and opening
The Hacienda initially began as a hotel-casino project called Lady Luck, which was being planned by Carlton Adair in 1954. Adair had several partners in the project, including Stanley Burke, a Sacramento man who owned the land. Adair also brought in Warren "Doc" Bayley, a travel columnist and owner of several Hacienda motels in Fresno, Bakersfield, and Indio, California. Under the deal, Adair and his group would have interest in the casino, while Burke would own the land and buildings. Bayley would be in charge of the hotel portion. The owners hoped to have the project finished before the opening of the Tropicana resort down the street.
The Lady Luck project received approval from the Clark County Planning Commission in January 1955, and construction was underway later that year. The project struggled to get investors, and its financing fell apart before construction reached the halfway mark. Bayley took over the project, renamed it the Hacienda, and removed Adair, leaving only Bayley and Burke. Bayley agreed to lease the property for $55,000 per month for 15 years.
The Hacienda was designed by Homer A. Rissman, and was built like other Las Vegas properties at the time, with a central building for the casino and restaurants, and motel structures to provide lodging. Rissman designed the project so that each motel building would connect to the casino via glass-walled corridors. Before it opened, the Hacienda included a 300-seat dining theater. Because of the high cost for performers, the Hacienda owners decided to refocus the space on hosting conventions rather than live entertainment, which instead would be offered in a lounge.
The hotel portion opened in June 1956. Because Bayley and Burke lacked casino experience, they chose Jake Kozloff, a Las Vegas casino investor, to manage the gaming operations. However, the Hacienda was denied a gaming license, as the Nevada Gaming Control Board was opposed to Kozloff's involvement because of past activities. A gaming license was issued after Kozloff was removed from the project, and the casino eventually opened on October 17, 1956. The $6 million Hacienda had 266 rooms and the largest swimming pool on the Las Vegas Strip. Like the other Hacienda hotels, the Las Vegas property featured a roadsign neon sign that depicted a cowboy riding a palomino horse. It was designed by YESCO and was among the company's most popular signs.
The Hacienda was built on the south end of the Las Vegas Strip, making it the first resort to be seen by motor tourists arriving from California. It sat alone at the time, surrounded by desert and away from the other resorts on the Strip. Gaming executives initially predicted that the Hacienda would struggle due to its location, although the resort prospered for many years. Its remote location ensured that most guests stayed on the property rather than visiting other resorts. The Hacienda was also popular because of its location near the McCarran International Airport, although the resort never had the same success as other Strip properties such as the Dunes and the Sands. Because it lacked the same elegance as other resorts on the Strip, the Hacienda received the negative nickname "Hayseed Heaven". The Hacienda was built as a budget resort and was the first Las Vegas resort aimed at attracting families. It included a go-cart track and a miniature golf course for children, and Las Vegas' first par 3 golf course. It also offered the Palomino room, which was used for shows and small parties.
In 1957, a few months after the opening, Kozloff filed a writ of attachment against the Hacienda, alleging that he was owed $71,000 from a loan he made to the property. The hotel posted a bond which nullified the writ. Three months later, Burke made various allegations against Bayley and requested that the Hacienda be placed into receivership. Bayley denied the allegations, which included a claim that he had mishandled finances. Later that year, plans were being made to add additional hotel rooms.
Promotion
Bayley devised numerous ideas to promote the resort. Shortly after its opening, he formed Hacienda Airlines, offering packages that included transportation from Los Angeles to the Hacienda as well as a room and some casino chips. The airline service proved to be successful, prompting Bayley to increase the number of planes. Its success was attributed to low fares, frequent advertising in California, and its catering to working-class tourists. The service would later extend to other U.S. cities. The airline included DC-3s, DC-4s and Lockheed Constellations, eventually numbering as many as 30 aircraft. One plane included a piano bar with actor Dick Winslow, who provided musical entertainment during the ride. The flights also offered champagne, and featured young women modeling lingerie for the passengers, who were mostly men. By the end of 1960, the Hacienda had flown in 150,000 people, making it the largest consumer of California champagne.
The flights eventually stopped in 1962, following an order from the Civil Aeronautics Board (CAB). The agency alleged that the Hacienda was operating as an airline, and the resort was not licensed to provide such service. The Hacienda denied this and stated that its guests were flown in for free, saying that they paid only for food and a hotel room. However, because guests paid before boarding the plane, CAB determined that they were essentially paying for a plane fare.
The resort also offered the Hacienda Holiday, a promotional program for tourists in which $10 casino chips were given away as part of a $16 package deal. In 1958, the Clark County licensing board ordered the Hacienda to halt this program, objecting to the fact that the chips were redeemable in the casino. The board said that these chips could be used for other services, but it was opposed to their use in the casino, stating that this would promote gambling. The promotion would be offered for at least the next 20 years, eventually becoming the Hacienda Champagne Holiday.
From December 1958 to February 1959, the Hacienda sponsored a flight endurance record when two men took turns flying a Cessna 172 across the southwestern United States for a period of 64 days. However, the promotion did not turn out as planned. Newspapers did not report on the story until 30 days after the plane took off, and they declined to mention the Hacienda. Dick Taylor, the Hacienda's general manager, said, "The papers, detecting a publicity stunt, did what they felt they had to do. They deleted the Hacienda name from all reports, and even went so far as to blank out the Hacienda name that was painted so large along the side of the plane."
Ownership changes
Bayley died of a heart attack in 1964, and his widow, Judith Bayley, took over the Hacienda. At the time, Bayley was the only female casino owner in Las Vegas, earning her a nickname as the "First Lady of Gambling". She lacked business training, and found the casino operation to be more complicated than initially expected. She lost hundreds of dollars in her first few months. Under her management, the Hacienda offered shuffleboard and babysitting services for guests, maintaining its appeal as a family resort. A lounge, known as the Jewel Box, was remodeled and reopened in 1965, followed by the opening of a keno room. Las Vegas mayor Oran Gragson attended both openings. One county commissioner had opposed the keno addition, stating that it would add a "honky tonk" atmosphere that was common in the city's Fremont Street area. In 1966, the Clark County Commission threatened to shut down the Hacienda unless Bayley made improvements to a resort that her company was building at Mount Charleston.
To focus on the Las Vegas Hacienda, Bayley sold off the California hotels in 1970, with the exception of one located in El Segundo. In December 1971, Judy Bayley died of cancer at the age of 56. Bayley's estate left the Hacienda to her assistant Joan Rashbrook and lawyer Calvin Magleby. Several weeks after Bayley's death, Magleby announced that American Mining and Smelting Inc. would purchase the Hacienda, with plans for expansion and remodeling of the resort. However, the sale was never completed. Later in 1972, the Hacienda was sold for $5 million to a group of buyers, which included Allen R. Glick, Paul Lowden, and Eugene Fresch. Lowden had raised $250,000 to purchase a 15-percent interest in the property, and he also became the resort's entertainment director.
In 1973, the Hacienda began construction on Travel World, an adjacent RV park for its guests. In 1974, the Hacienda became part of Glick's company, Argent Corporation, which held a controlling interest. Fresch and Lowden also retained interests. The 452-space RV park, later called Ramada Camp Inn, was opened in 1975. It was part of a $7 million renovation of the resort. In 1976, Argent announced that it would sell the Hacienda for $21 million to Hawaiian businessman Joseph Gennitti, who would also take over $11 million in debt. The deal ended after Gennitti failed to provide Glick with details about financing the purchase. Subsequently, two opposing investment groups began negotiations to purchase the Hacienda. Later that year, state investigators found that money had been skimmed from slot machines at Glick's casinos, including the Hacienda.
In January 1977, it was announced that Lowden, the hotel's president, would purchase the remaining interest from Argent and Fresch for $21 million. Lowden worked with several individuals to raise money for his purchase. The Nevada Gaming Control Board accused Lowden of being deceitful, alleging that people with questionable records would have hidden interests in the Hacienda and control over it. Lowden denied this, stating that he would be the sole buyer. The board recommended against his purchase, but was overridden by the Nevada Gaming Commission. According to commission chairman Harry Reid, there was no evidence of hidden interests. He said that audit agents in the case "didn't do a very good job in their investigation." The sale was completed in July 1977.
In 1978, the Hacienda began offering deluxe rooms and suites as timeshares. Within two years, the hotel had 3,000 timeshare members. The Hacienda was associated with Resort Condominiums International, an exchange network that allowed timeshare owners to trade their units. The Little Church of the West, located further north on the Strip, was relocated to the Hacienda property in 1979, making room for the new Fashion Show Mall. By 1980, the Hacienda included a popular steakhouse known as the Charcoal Room. A $30 million expansion of the Hacienda was underway in 1980, scheduled for completion later that year. It included an 11-story tower with 300 rooms, adding on to the hotel's 538-room count. Also added was a convention center, known as the Matador Arena. In addition to small conventions, it also hosted monthly, televised matches between professional boxers.
At the end of 1982, Wayne Newton was in discussions to become a co-owner in the Hacienda, as well as Lowden's other Strip resort, the Sahara. After two months of negotiations, Newton decided against the idea, as he was considering other resorts for purchase. In the mid-1980s, the RV park operated as the Hacienda Adventure Camperland. It occupied 16 acres, and included 451 hook-ups, a pool, and a playground. In 1989, Lowden announced a $30 million plan to add a 400-room tower and to expand the casino. The tower was completed in 1991, bringing the room count to 1,137. The expansion also doubled the casino.
Final years
In its final years, the Hacienda was owned by Lowden through his company, Sahara Gaming Corporation. The resort struggled as new megaresorts were opened nearby, including the Excalibur (1990) and the Luxor (1993), both owned by Circus Circus Enterprises. In September 1994, Sahara Gaming stated that it was receiving offers to purchase the Hacienda, and that such offers would be considered for the right price. In January 1995, Bill Bennett announced that he would buy the Hacienda and adjacent acreage. Bennett was a director for Circus Circus Enterprises and had previously served as the company chairman. Bennett planned to rename the Hacienda and give it a South American theme. His plans would include extensive renovations and the addition of approximately 2,000 hotel rooms. However, his impending purchase was complicated by a corporate clause which would give Circus Circus Enterprises the right to purchase the resort instead of him.
Shortly after Bennett's plans were announced, Circus Circus filed a lawsuit to prevent his purchase, stating that he was aware of the company's plans to buy the property and that he proceeded anyway. The Hacienda occupied 47 acres, and Circus Circus wanted to buy an adjacent 74 acres to build a new resort on both parcels, connecting with the Luxor and Excalibur. Bennett and Circus Circus agreed to a settlement in March 1995, allowing the company to buy the Hacienda for $80 million and the 74 acres for another $73 million. Lowden said that an inability to reach an agreement with the Culinary Workers Union was a major factor in choosing to sell the Hacienda.
The Hacienda's impending closure was announced in September 1996, as Circus Circus proceeded with plans to replace it. The closure would affect 900 employees. After 40 years, the Hacienda closed at 4:00 p.m. on December 1, 1996. The resort's fixtures and hotel furnishings were donated to local charities. A few days later, the Little Church of the West was relocated down the street. The resort's horse and rider neon sign was also saved, being put on display in downtown Las Vegas. The Neon Museum had the sign refurbished at a cost of $60,000, and it was then installed in its new location a couple weeks prior to the Hacienda's closure. Before the Hacienda was demolished, the stairwells and stripped interiors of the hotel were used in a firefighter training mission to aid them in the event of a real high-rise fire. More than 30 local firefighters rushed through the hotel in reaction to an imaginary fire, situated on the fifth floor.
Controlled Demolition, Inc. (CDI) was hired to demolish the 11-story hotel through implosion. CDI was usually given six months' notice, although Circus Circus Enterprises wanted the Hacienda demolished in 30 days for New Year's Eve, as part of a televised event that would compete with the annual Times Square Ball celebration in New York City. After the Hacienda's closure, salvage crews removed equipment such as air conditioners, and they had to knock out walls in the hotel's southern end stairwell. This presented a potential problem for CDI, as wall strength is an important factor in properly controlling an implosion. CDI expected that the south end would not fall with the rest of the hotel. All of the walls in the hotel were built to be reinforced.
The implosion took place on the night of December 31, 1996, and was televised as the culmination of Fox's New Year's special Sinbad's Dynamite New Year's Eve, where it aired approaching midnight ET. The coverage featured a cameo by ring announcer Michael Buffer. A six-minute fireworks show led up to the implosion at 9:00 p.m. More than 1,000 pounds of explosives were used for the implosion, which was watched by a crowd of more than 300,000 people. As expected, the southern end of the hotel did not fall. The next day, a crew was brought in to bring down the remaining structure with a wrecking ball. Thousands of spectators gathered to watch the final demolition.
Circus Circus Enterprises opened the Mandalay Bay resort on March 2, 1999, replacing the Hacienda. The company also licensed the Hacienda name to the Hacienda Hotel and Casino near Boulder City, Nevada. The name also continues to live on through Hacienda Avenue, a road that runs along the Mandalay Bay property, although a small portion was renamed Mandalay Bay Road.
Entertainers and shows
When the Hacienda opened, several other Las Vegas resorts had suffered financially after competing for high-priced entertainers. Initially, the Hacienda owners did not intend to battle for top performers, and the only live entertainment would be lounge acts. In the late 1950s, the Hacienda debuted a show by Cole Porter called Can-Can. In 1964, the resort hosted the puppet show Les Poupées de Paris. Comedian Hank Henry also performed at the Hacienda during the mid-1960s. The resort also offered shows such as Strictly Burlesque and Topless Models. After taking ownership of the Hacienda, Glick said in 1973 that the resort would return to the "friendly image of the past" by eliminating nude stage shows.
In 1967, the Hacienda hosted a two-hour late-night TV program called The Las Vegas Show on the fledgling United Network. Hosted by Bill Dana and featuring regulars Ann Elder, Pete Barbutti, Danny Meahan, Joanne Worley, Cully Richards and Jack Sheldon, the show (and the network) were shut down after only a month on the air.
In the mid-1970s, the resort offered a nude ice-skating show called Spice on Ice, although it eventually lost interest among audiences as other resorts opened their own topless ice shows. Spice on Ice ran for four years, and was replaced by an ice-skating variety show, Ice Fantasy, in 1977. Another ice show, titled Fire and Ice, debuted in 1982, in the resort's Fiesta showroom. The show included Albert Lucas, who would juggle while ice-skating. The show eventually ended, but returned in 1989, when the Hacienda began reviving its old ice shows. At the time, the show consisted of comedy acts and ice skating.
Comedian Redd Foxx was a frequent performer at the Hacienda during the late 1980s, and he later got married at the Little Church of the West. Magician Lance Burton performed at the Hacienda from 1991 to 1996.
References
Defunct casinos in the Las Vegas Valley
Defunct hotels in the Las Vegas Valley
Casinos completed in 1956
Hotel buildings completed in 1956
Hotels established in 1956
1956 establishments in Nevada
1996 disestablishments in Nevada
Skyscraper hotels in Paradise, Nevada
Demolished hotels in Clark County, Nevada
Buildings and structures demolished in 1996
Buildings and structures demolished in 1997
Casino hotels
Buildings and structures demolished by controlled implosion | Hacienda (resort) | Engineering | 4,423 |
27,944,552 | https://en.wikipedia.org/wiki/Andrei%20Monin | Andrei Sergeyevich Monin (; 2 July 1921 – 22 September 2007) was a Soviet and Russian geophysicist, mathematician, and oceanographer. Monin was known for his contributions to statistical theory of turbulence and atmospheric physics. He served as the Director of the P.P. Shirshov Institute of Oceanology of the Academy of Sciences of the Soviet Union. He was instrumental in developing the Shirshov Institute into one of the largest scientific centers for ocean and earth science studies.
The Monin–Obukhov similarity theory and the Monin–Obukhov length are named after Monin and Russian Academician Alexander Obukhov.
Life and work
Monin was born in Moscow to Sergei Aleksandrovich Monin, an Assistant Professor of the Moscow Pedagogical Institute. He joined the Mechanical and Mathematical Faculty of the Lomonosov Moscow State University in 1938 and received his bachelor's degree in 1942. Monin then enrolled for the post-graduate programme in the same university.
Military career
In 1943, Monin was called up for military service in the ranks of the Red Army where he was asked to join the military courses of weather forecasters organized at the Higher Hydrometeorological Institute of the Red Army. He joined in the rank of lieutenant and sent to the 3rd Baltic Front where he was section leader of a frontal meteorological station. He served in the army during the whole military campaign from the liberation of Pskov until the liberation of Riga. In 1945, Monin was attached to the Central Institute of Weather Forecasting of the Red Army. In 1946, he was demobilized and worked as a research fellow at the Central Institute of Weather Forecasting.
Education and early career
In 1946, Monin came back to Moscow State University to continue his post-graduate programme under the direct guidance of Academician Andrey Kolmogorov who prepared and defended his Candidate's thesis on the theory of atmospheric turbulence. In 1951 Monin started to work at the Atmospheric Physics Department at Geophysical Institute of the Academy of Sciences of the Soviet Union, which later recognized as the Atmospheric Physics Institute (presently The Obhukov Institute of Atmospheric Physics). At the latter Institute he was a senior scientist, Head of a department and a scientific consultant. In 1956 he defended his Doctor's thesis on the theory of turbulent diffusion.
Awards and honors
A. S. Monin had received many honors and medals: among them are:
Foreign member of the American Academy of Arts and Sciences, 1973.
Foreign member of the United States National Academy of Sciences, 1976.*Honorary Doctor of the University of Gothenburg, Sweden, 1986.
Academician of the Russian Academy of Natural Sciences, 1991.
USSR State Prize, 1980.
Yuly Shokalsky Prize, 1986.
Alexander Friedmann Prize by Russian Academy of Sciences in 1993.
Books authored
Monin was a prolific author of scientific works on various topics, including theory of turbulence, atmospheric physics, planetology, and meteorology. He was the author of about 620 scientific publications, including 24 monographs and the ten-volume "Okeanologia". Almost all of his books have been translated into foreign languages.
Noted for its clarity as well as its comprehensive treatment, the book "Statistical Fluid Mechanics: Mechanics of Turbulence", co-authored with Akiva Yaglom, is considered to be a classic work on theory of turbulence. Science while reviewing this book had observed: "If ever a book on turbulence could be called definitive, it is this book by two of Russia's most eminent and productive scientists in turbulence, oceanography, and atmospheric physics."
A. S. Monin, An Introduction to the Theory of Climate, D. Reidel Publishing Company, Netherlands, 1986.
A. S. Monin, Theoretical Geophysical Fluid Dynamics, Kluwer Academic Publishers, Netherlands, 1990.
A. S. Monin and A. M. Yaglom, Statistical Fluid Mechanics: Mechanics of Turbulence, Dover Publications, 2007.
A. S. Monin, Weather Forecasting as a Problem in Physics, The MIT Press, 1972.
A. S. Monin and R. V. Ozmidov, Turbulence in the Ocean, D. Reidel Publishing Company, Netherlands, 1985.
References
External links
Monin Andrei Sergeyevich at the Russian Academy of Sciences
1921 births
2007 deaths
20th-century Russian physicists
Scientists from Moscow
Academic staff of the Moscow Institute of Physics and Technology
Corresponding Members of the USSR Academy of Sciences
Fellows of the American Academy of Arts and Sciences
Foreign associates of the National Academy of Sciences
Full Members of the Russian Academy of Sciences
Moscow State University alumni
Recipients of the Order of the October Revolution
Recipients of the Order of the Red Banner of Labour
Recipients of the USSR State Prize
Fluid dynamicists
Russian geophysicists
Russian meteorologists
Russian oceanographers
Soviet geophysicists
Soviet meteorologists
Soviet military personnel of World War II
Soviet oceanographers
Burials in Troyekurovskoye Cemetery | Andrei Monin | Chemistry | 1,007 |
28,368,138 | https://en.wikipedia.org/wiki/ChinaJoy | ChinaJoy, formally China Digital Entertainment Expo and Conference () is a digital entertainment expo held annually in Shanghai, China.
The exhibition is the largest gaming and digital entertainment exhibition held in China and Asia.
References
External links
ChinaJoy website
ChinaJoy website
The 4th China Digital Entertainment Expo & Conference (ChinaJoy) (Shanghai Cultural Information)
China Digital Entertainment Expo & Conference (2010). In Show Intro. Second part. Retrieved 11 August 2010.
2004 establishments in China
Annual events in Shanghai
Recurring events established in 2004
Trade fairs in China
Tourist attractions in Shanghai
Video game trade shows
Video gaming in China | ChinaJoy | Technology | 119 |
13,412,910 | https://en.wikipedia.org/wiki/Joking%20relationship | In anthropology, a joking relationship is a relationship between two people that involves a ritualised banter of teasing or mocking.
In Niger it is listed on the Representative List of the Intangible Cultural Heritage of Humanity.
Structure
Analysed by British social anthropologist Alfred Radcliffe-Brown in 1940, it describes a kind of ritualised banter that takes place, for example between a man and his maternal mother-in-law in some South African indigenous societies. Two main variations are described: an asymmetrical relationship where one party is required to take no offence at constant teasing or mocking by the other, and a symmetrical relationship where each party makes fun at the other's expense.
The joking relationship is an interaction that mediates and stabilizes social relationships where there is tension, competition, or potential conflict, such as between in-laws and between clans and tribes.
Extent
While first documented academically by Radcliffe-Brown in the 1920s, this type of relationship is now understood to be very widespread across societies in general. In West Africa, particularly in Mali, it is regarded as a centuries-old cultural institution known as sanankuya.
Antithesis
This type of relationship contrasts strongly with societies where so-called avoidance speech or "mother-in-law" language is imposed to minimise interaction between the two parties, as in many Australian Aboriginal languages. Donald F. Thomson's article "The Joking Relationship and Organized Obscenity in North Queensland" gives an in-depth discussion of a number of societies where these two speech styles co-exist. The joking relationships which are most unconstrained and free are between classificatory Father's Father and Son's Son—which appears to be the same situation in the Plains cultures of North America.
See also
Dozens (game)
Sources
Further reading
External links
Alfred Radcliffe-Brown Biography from Answers.com
Interpersonal relationships
Social anthropology | Joking relationship | Biology | 381 |
8,815,878 | https://en.wikipedia.org/wiki/CXCL5 | C-X-C motif chemokine 5 (CXCL5 or ENA78) is a protein that in humans is encoded by the CXCL5 gene.
Function
The protein encoded by this gene, CXCL5 is a small cytokine belonging to the CXC chemokine family that is also known as epithelial-derived neutrophil-activating peptide 78 (ENA-78). It is produced following stimulation of cells with the inflammatory cytokines interleukin-1 or tumor necrosis factor-alpha. Expression of CXCL5 has also been observed in eosinophils, and can be inhibited with the type II interferon IFN-γ. This chemokine stimulates the chemotaxis of neutrophils possessing angiogenic properties. It elicits these effects by interacting with the cell surface chemokine receptor CXCR2. The gene for CXCL5 has four exons and is located on human chromosome 4 amongst several other CXC chemokine genes. CXCL5 has been implicated in connective tissue remodelling. CXCL5 has been also described to regulate neutrophil homeostasis.
Clinical significance
CXCL5 plays a role in reducing sensitivity to sunburn pain in some subjects, and is a "potential target which can be utilized to understand more about pain in other inflammatory conditions like arthritis and cystitis.". CXCL5 is well known to have chemotactic and activating functions on neutrophil, mainly during acute inflammatory responses. However CXCL5 expression is also higher in atherosclerosis (a chronic inflammatory condition) but is not associated with neutrophil infiltration. Instead CXCL5 has a protective role in atherosclerosis by directly controlling macrophage foam cell formation.
References
External links
Further reading
Cytokines | CXCL5 | Chemistry | 408 |
62,052,741 | https://en.wikipedia.org/wiki/NGC%204320 | NGC 4320, is a peculiar galaxy located about 370 million light-years away in the constellation Virgo. It was discovered by astronomer Heinrich d'Arrest on April 15, 1865 and is a member of the NGC 4325 Group.
NGC 4320 appears to be the end result of an interaction and merger of two spiral galaxies.
See also
List of NGC objects (4001–5000)
Antennae Galaxies
Mice Galaxies
References
External links
4320
040160
Virgo (constellation)
Astronomical objects discovered in 1865
Spiral galaxies
07452
Peculiar galaxies
Interacting galaxies
NGC 4325 Group | NGC 4320 | Astronomy | 115 |
23,975,003 | https://en.wikipedia.org/wiki/C12H14O4 | {{DISPLAYTITLE:C12H14O4}}
The molecular formula C12H14O4 (molar mass: 222.23 g/mol, exact mass: 222.0892 u) may refer to:
Apiole
Blattellaquinone
Diethyl phthalate
Dillapiole
Monobutyl phthalate
Pseudodillapiole | C12H14O4 | Chemistry | 81 |
324,502 | https://en.wikipedia.org/wiki/Tantric%20sex | Tantric sex or sexual yoga refers to a range of practices in Hindu and Buddhist tantra that utilize sexual activity in a ritual or yogic context. Tantric sex is associated with antinomian elements such as the consumption of alcohol, and the offerings of substances like meat to deities. Moreover, sexual fluids may be viewed as power substances and used for ritual purposes, either externally or internally.
The actual terms used in the classical texts to refer to this practice include "Karmamudra" (Tibetan: ལས་ཀྱི་ཕྱག་རྒྱ las kyi phyag rgya, "action seal") in Buddhist tantras and "Maithuna" (Devanagari: मैथुन, "coupling") in Hindu sources. In Hindu Tantra, Maithuna is the most important of the five makara (five tantric substances) and constitutes the main part of the Grand Ritual of Tantra variously known as Panchamakara, Panchatattva, and Tattva Chakra. In Tibetan Buddhism, karmamudra is often an important part of the completion stage of tantric practice.
While there may be some connection between these practices and the Kāmashāstra literature (which include the Kāmasūtra), the two practice traditions are separate methods with separate goals. As the British Indologist Geoffrey Samuel notes, while the kāmasāstra literature is about the pursuit of sexual pleasure (kāmā), sexual yoga practices are often aimed towards the quest for liberation (moksha).
History
In its earliest forms, Tantric intercourse was usually directed to generate sexual fluids that constituted the "preferred offering of the Tantric deities." While there is already a mention of ascetics practicing it in the 4th century CE Mahabharata, those techniques were rare until late Buddhist Tantra. Up to that point, sexual emission was both allowed and emphasized. Around the start of the first millennium, Tantra began to include practices of semen retention, like the penance ceremony of asidharavrata and the posterior yogic technique of vajroli mudra. They were probably adopted from ancient, non-Tantric celibate schools, like those mentioned in Mahabharata.
The Brhadaranyaka Upanisad contains various sexual rituals and practices which are mostly aimed at obtaining a child which are concerned with the loss of male virility and power. One passage from the Brhadaranyaka Upanishad states:
Her vulva is the sacrificial ground; her pubic hair is the sacred grass; her labia majora are the Soma-press; and her labia minora are the fire blazing at the centre. A man who engages in sexual intercourse with this knowledge obtains as great a world as a man who performs a Soma sacrifice, and he appropriates to himself the merits of the women with whom he has sex. The women, on the other hand, appropriate to themselves the merits of a man who engages in sexual intercourse with them without this knowledge. (Brhadaranyaka Upanishad 6.4.3, trans. Olivelle 1998: 88)
According to Samuel, late Vedic texts like the Jaiminiya Brahmana, the Chandogya Upanisad, and the Brhadaranyaka Upanisad, "treat sexual intercourse as symbolically equivalent to the Vedic sacrifice, and ejaculation of semen as the offering." However, he also writes that while it is possible that some kind of sexual yoga existed in the fourth or fifth centuries, "Substantial evidence for such practices, however, dates from considerably later, from the seventh and eighth centuries, and derives from Saiva and Buddhist Tantric circles."
Tantric sexual practices are often seen as exceptional and elite, and not accepted by all sects. They are found only in some tantric literature belonging to Buddhist and Hindu Tantra, but are entirely absent from Jain Tantra. In the Kaula tradition and others where sexual fluids as power substances and ritual sex are mentioned, scholars disagree in their translations, interpretations and practical significance.
Emotions, eroticism and sex are universally regarded in Tantric literature as natural, desirable, a means of transformation of the deity within. Pleasure and sex is another aspect of life and a "root of the universe", whose purpose extends beyond procreation and is another means to spiritual journey and fulfillment. This idea flowers with the inclusion of kama art in Hindu temple arts, and its various temple architecture and design manuals such as the Shilpa-prakasha by the Hindu scholar Ramachandra Kulacara.
Practice
In Hinduism
The actual term used in Hindu classical texts to refer to this practice is (Devanagari: मैथुन, "coupling"). In the Hindu Tantras, is always presented in the context of (the five or tantric substances) which constitutes primary ritual of Tantra. These may also be referred to as "the five Ms", or the , which consist of (alcohol), (meat), (fish), (pound grain), and (sexual intercourse). Taboo-breaking elements are only practiced literally by "left-hand path" tantrics (vāmācārins), whereas "right-hand path" tantrics (dakṣiṇācārins) use symbolic substitutes.
Jayanta Bhatta, the 9th-century scholar of the Nyaya school of Hindu philosophy and who commented on Tantra literature, stated that the Tantric ideas and spiritual practices are mostly well placed, but it also has "immoral teachings" such as by the so-called "Nilambara" sect where its practitioners "wear simply one blue garment, and then as a group engage in unconstrained public sex" on festivals. He wrote, this practice is unnecessary and it threatens fundamental values of society. This sect might have been an offshoot of the Pashupata Shaivite school, or possibly a Buddhist cult of Vajrapani.
Ascetics of the Shaivite school of Mantramarga, in order to gain supernatural power, reenacted the penance of Shiva after cutting off one of Brahma's heads (Bhikshatana). They worshipped Shiva with impure substances like alcohol, blood and sexual fluids generated in orgiastic rites with their consorts.
Douglas Renfrew Brooks states that the antinomian elements such as the use of intoxicating substances and sex were not animistic, but were adopted in some Kaula traditions to challenge the Tantric devotee to break down the "distinctions between the ultimate reality of Brahman and the mundane physical and mundane world". By combining erotic and ascetic techniques, states Brooks, the Tantric broke down all social and internal assumptions, became Shiva-like. In Kashmir Shaivism, states David Gray, the antinomian transgressive ideas were internalized, for meditation and reflection, and as a means to "realize a transcendent subjectivity".
As part of tantric inversion of social regulations, sexual yoga often recommends the usage of consorts from the most taboo groups available, such as close relatives or people from the lowest, most contaminated castes. They must be young and beautiful, as well as initiates in tantra.
In Buddhism
According to English, Buddhist sexual rites were incorporated from Shaiva tantra. One of the earliest mentions of sexual yoga is in the Mahayana Buddhist Mahāyānasūtrālamkāra of Asanga (c. 5th century). The passage states:
Supreme self-control is achieved in the reversal of sexual intercourse in the blissful Buddha-poise and the untrammelled vision of one's spouse.
According to David Snellgrove, the text's mention of a ‘reversal of sexual intercourse’ might indicate the practice of withholding ejaculation. Snellgrove states:
It is by no means improbable that already by the fifth century when Asanga was writing, these techniques of sexual yoga were being used in reputable Buddhist circles, and that Asanga himself accepted such a practice as valid. The natural power of the breath, inhaling and exhaling, was certainly accepted as an essential force to be controlled in Buddhist as well as Hindu yoga. Why therefore not the natural power of the sexual force? [...] Once it is established that sexual yoga was already regarded by Asanga as an acceptable yogic practice, it becomes far easier to understand how Tantric treatises, despite their apparent contradiction of previous Buddhist teachings, were so readily canonized in the following centuries.
Deities like Vajrayogini, sexually suggestive and streaming with blood, overturn traditional separation between intercourse and menstruation. Some extreme texts would go further, such as the 9th-century Buddhist text Candamaharosana-tantra, which advocated consumption of bodily waste products of the practitioner's sexual partner, like wash-water of her anus and genitalia. Those were thought to be "power substances", teaching the waste should be consumed as a diet "eaten by all the Buddhas."
Japanese Buddhism
12th-century Japanese school Tachikawa-ryu did not discourage ejaculation in itself, considering it a "shower of love that contained thousands of potential Buddhas". They employed emission of sexual fluids in combination with worshipping of human skulls, which would be coated in the resultant mix in order to create honzon. However, those practices were considered heretical, leading to the sect's suppression.
Tibetan Buddhism
In Tibetan Buddhism, the higher tantric yogas are generally preceded by preliminary practices (Tib. ngondro), which include sutrayana practices (i.e. non-tantric Mahayana practices) as well as preliminary tantric meditations. Tantric initiation is required to enter into the practice of tantra.
Tibetan tantric practice refers to the main tantric practices in Tibetan Buddhism. The great Rime scholar Jamgön Kongtrül refers to this as "the Process of Meditation in the Indestructible Way of Secret Mantra" and also as "the way of mantra," "way of method" and "the secret way" in his Treasury of Knowledge. These Vajrayāna Buddhist practices are mainly drawn from the Buddhist tantras and are generally not found in "common" (i.e. non-tantric) Mahayana. These practices are seen by Tibetan Buddhists as the fastest and most powerful path to Buddhahood.
Unsurpassable Yoga Tantra, (Skt. anuttarayogatantra, also known as Mahayoga) are in turn seen as the highest tantric practices in Tibetan Buddhism. Anuttarayoga tantric practice is divided into two stages, the generation stage and the completion stage. In the generation stage, one meditates on emptiness and visualizes one's chosen deity (yidam), its mandala and companion deities, resulting in identification with this divine reality (called "divine pride"). This is also known as deity yoga (devata yoga).
In the completion stage, the focus is shifted from the form of the deity to direct realization of ultimate reality (which is defined and explained in various ways). Completion stage practices also include techniques that work with the subtle body substances (Skt. bindu, Tib. thigle) and "vital winds" (vayu, lung), as well as the luminous or clear light nature of the mind. They are often grouped into different systems, such as the six dharmas of Naropa, or the six yogas of Kalachakra.
Karmamudrā refers to the female yogini who engages in such a practice and the technique which makes use of sexual union with a physical or visualized consort as well as the practice of inner heat (tummo) to achieve a non-dual state of bliss and insight into emptiness. In Tibetan Buddhism, proficiency in tummo yoga, a completion stage practice, is generally seen as a prerequisite to the practice of karmamudrā.
See also
Coitus reservatus
Mahamudra
Yab-yum
Yogini
References
Works cited
Further reading
Tantra
Vajrayana
Tantric practices
Human sexuality
Sexual acts
Sexuality and religion | Tantric sex | Biology | 2,517 |
61,889 | https://en.wikipedia.org/wiki/Division%20%28taxonomy%29 | <noinclude>
Division is a taxonomic rank in biological classification that is used differently in zoology and in botany.
In botany and mycology, division is the traditional name for a rank now considered equivalent to phylum. The use of either term is allowed under the International Code of Botanical Nomenclature.
The main Divisions of land plants are the Marchantiophyta (liverworts), Anthocerotophyta (hornworts), Bryophyta (mosses), Filicophyta (ferns), Sphenophyta (horsetails), Cycadophyta (cycads), Ginkgophyta (ginkgo)s, Pinophyta (conifers), Gnetophyta (gnetophytes), and the Magnoliophyta (Angiosperms, flowering plants). The Magnoliophyta now dominate terrestrial ecosystems, comprising 80% of vascular plant species.
In zoology, the term division is applied to an optional rank subordinate to the infraclass and superordinate to the legion and cohort. A widely used classification (e.g. Carroll 1988) recognises teleost fishes as a Division Teleostei within Class Actinopterygii (the ray-finned fishes). Less commonly (as in Milner 1988), living tetrapods are ranked as Divisions Amphibia and Amniota within the clade of vertebrates with fleshy limbs (Sarcopterygii).
Proposals for standardisation
In 1978, a group of botanists including Harold Charles Bold, Arthur Cronquist and Lynn Margulis proposed replacing the term "division" with "phylum" in botanical nomenclature, arguing that maintaining different terms for the same taxonomic rank across biological kingdoms created unnecessary confusion. This was particularly problematic for unicellular eukaryotes, where heterotrophic organisms were classified under zoological nomenclature (using "phylum") while autotrophic organisms fell under botanical nomenclature (using "division"). They proposed updating the International Code of Botanical Nomenclature to use "phylum" and "subphylum" throughout, while maintaining that names originally published as divisions would be treated as if they had been published as phyla.
Molecular phylogenetic classification
The use of molecular methods, particularly 16S ribosomal RNA analysis, helped establish major bacterial divisions in the 1980s. In 1985, Carl Woese and colleagues identified ten major groups of eubacteria through oligonucleotide signature analysis, noting that these groupings were "appropriately termed eubacterial Phyla or Divisions." This work provided early molecular evidence for the equivalence of bacterial divisions with phyla and helped establish a phylogenetic basis for high-level bacterial classification.
Viruses and prokaryotes
In 2020, the International Committee on Taxonomy of Viruses (ICTV) formalised a 15-rank hierarchical classification system, ranging from the highest rank "realm" (rather than domain) down through the lower ranks, notably using "phylum" rather than "division". Under this system, the first viral realm established was Riboviria, encompassing all RNA viruses that encode an RNA-directed RNA polymerase.
In 2021, the International Code of Nomenclature of Prokaryotes (ICNP) formally included the rank of phylum for the first time, adopting the suffix "-ota" for phylum names. This led to the publication of names for 46 prokaryotic phyla with cultured representatives, replacing some established names with neologisms – for example, "Proteobacteria" became "Pseudomonadota" and "Firmicutes" became "Bacillota".
References
Works cited
Scientific classification
Botanical nomenclature | Division (taxonomy) | Biology | 778 |
75,469,450 | https://en.wikipedia.org/wiki/Aldafermin | Aldafermin is a fibroblast growth factor 19 (FGF19) analogue developed for non-alcoholic steatohepatitis.
References
Experimental drugs developed for non-alcoholic fatty liver disease | Aldafermin | Chemistry | 43 |
37,595,113 | https://en.wikipedia.org/wiki/Glaeser%27s%20composition%20theorem | In mathematics, Glaeser's theorem, introduced by , is a theorem giving conditions for a smooth function to be a composition of F and θ for some given smooth function θ. One consequence is a generalization of Newton's theorem that every symmetric polynomial is a polynomial in the elementary symmetric polynomials, from polynomials to smooth functions.
References
Theorems in real analysis | Glaeser's composition theorem | Mathematics | 76 |
4,718,222 | https://en.wikipedia.org/wiki/Wizard%20of%20OS | For OpenBSD 3.7, released May 19, 2005, a theme song was made titled "The Wizard of OS". The song chronicled the OpenBSD developers' struggle to obtain open documentation for wireless cards and how manufacturers in Taiwan like Ralink and Realtek were the most cooperative of all the companies contacted. It was based on the work of Pink Floyd most notably in the style of their 1973 album The Dark Side of the Moon showing some similarities to "The Great Gig in the Sky", "Breathe" and "Eclipse". It is a parody of The Wizard of Oz.
It was for this effort which Theo de Raadt, the project's Benevolent Dictator for Life, received the FSF's 2004 Award for the Advancement of Free Software.
Personnels
Jonathan Lewis - lead vocals
Adele Legere - female vocals
Ty Semaka - lyrics, monkeys and laughing sounds
Anita Miotti - little girl voice
Reed Shimozawa - lead guitar
Jonathan Lewis - drums, bass and all other sounds
The song was co-arranged by Ty Semaka and Jonathan Lewis (who also recorded, mixed and mastered the song).
References
External links
http://www.openbsd.org/lyrics.html#37 - Lyrics and MP3/OGG downloads
OpenBSD
2005 songs | Wizard of OS | Technology | 265 |
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