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61,784,569 | https://en.wikipedia.org/wiki/Greenworld | Greenworld (Japanese: グリーンワールド Hepburn: Gurīn wārudo) is a 2010 speculative evolution and science fiction book written by Scottish geologist and paleontologist Dougal Dixon and primarily illustrated by Dixon himself, alongside a few images by other artists. Greenworld features a fictional alien planet of the same name and a diverse biosphere of alien organisms. Greenworld has so far only been published in Japan, where it was released in two volumes.
The premise of Greenworld follows human colonisation of the alien planet over the course of a thousand years, chronicling mankind's disastrous impact on Greenworld's ecosystems, similar to how humans today are impacting Earth and its life. Greenworld and its creatures were originally designed by Dixon as a design exercise for his local science fiction group and the planet and its organisms first appeared in a 1992 episode of the Channel 4 series Equinox, followed by appearances in various other media, including the 1997 programme Natural History of an Alien.
Greenworld's premise is similar to, and repurposed from, Dixon's original idea for his book Man After Man (1990), which would have involved humans time-travelling 50 million years into the future to colonize biosphere of the future he had developed for After Man (1981). The version of Man After Man that was eventually published was considerably different from Dixon's original concept.
Summary
Greenworld is a hypothetical Earth-like exoplanet with a diverse and thriving biosphere. All animal-analogous organisms on Greenworld are descended from a radially symmetrical six-legged starfish-like animal. Animals on Greenworld secondarily developed bilateral symmetry (which is what is seen in most animals on Earth), developing into two major groups; "sulcosyms" in which the plane of symmetry lies between the legs (meaning they have three pairs of limbs) and "brachiosyms" in which the plane of symmetry has led to the formation of one "arm" at each of its ends (meaning two pairs of limbs and two unpaired limbs, one at the front and one at the back).
In the book, humanity discovers Greenworld just as Earth finally collapses under the pressure of mankind's impact and a generation ship with ten thousand people is sent to colonize the planet. Greenworld then explores the first thousand years of human colonisation on the planet through following some key families of settlers. Over the course of this timespan, every ecological catastrophe caused by humans on Earth is repeated on Greenworld. The book is divided into several shorter chapters, each telling a short story and featuring illustrations of the local animals and their interactions and relations to humans. Illustrations also include "excerpts" of advertisements, science papers, field guides and recipes. By the end of the book, Greenworld and its ecosystems are in ruins, mankind having caused a mass extinction event through their actions on the planet.
Development
The fictional planet and biosphere featured in Greenworld was originally created as a design exercise by Dixon for his local science fiction group, basing it on the same biochemical processes behind the evolution of life on Earth. Before Dixon put the whole concept together as a cohesive book, parts of the project appeared in different media in which Dixon featured. In this capacity, Greenworld first appeared in the Channel 4 programme E.T, Please call Earth (part of the series Equinox) in 1992, followed by appearances in BBC's It'll Never Work?, The Radio Times and in BBC Focus in 1993 and it was one of many hypothetical alien worlds by different scientists featured on the BBC2/Discovery Channel programme Natural History of an Alien in 1997.
Following the success of his previous speculative evolution books After Man (1981) and The New Dinosaurs (1988), Dixon worked on a new project dubbed Man After Man which was to involve mankind avoiding catastrophes such as overpopulation and mass starvation by inventing time travel and moving 50 million years in the future to re-establish civilization. As such Man After Man would have been set in the same world as After Man and would have focused on the man-made catastrophes destroying the ecosystems Dixon had established in the previous book. The final version of Man After Man, published as a book in 1990, was instead focused on future climate change through the eyes of future human descendants genetically engineered to adapt to it and was a project Dixon was reluctant to be involved in. Dixon's original concept for Man After Man, the destruction of an established ecosystems by mankind, was instead eventually used for Greenworld, with Dixon applying it to the fictional alien world which he had created.
The majority of the illustrations in Greenworld were done by Dixon himself, though some images were also produced by other artists such as Julius T. Csotonyi and Margaret Walty. Although Greenworld has so far only been published in Japan, Dixon has expressed interest in getting an English-language version published. In the spring of 2021, the fictional biosphere of Greenworld was highlighted among other science fiction works at the exhibition "Interspecies Futures" at the Center for Book Arts in New York.
References
External links
Greenworld on Dougal Dixon's website
"Anatomy of an Alien V / Greenworld I" at Sigmund Nastrazzurro's blog Furahan Biology and Allied Matters, featuring images from Greenworld and a segment of the planet's 1997 appearance in Natural History of an Alien.
Archived 2010 website for Greenworld by Tokyo-based publisher Diamond.
Archived 2009 website for Greenworld by the Japanese Rights World Agency.
2010 science fiction novels
Science fiction books
Evolution in popular culture
Books about evolution
Speculative evolution
Japanese-language books
Books by Dougal Dixon | Greenworld | [
"Biology"
] | 1,159 | [
"Biological hypotheses",
"Speculative evolution",
"Hypothetical life forms"
] |
61,784,960 | https://en.wikipedia.org/wiki/Ethylene%20bis%28iodoacetate%29 | Ethylene bis(iodoacetate), also known as S-10, is the iodoacetate ester of ethylene glycol. It's an alkylating agent that has been studied as an anticancer drug.
See also
Ethylene glycol
Iodoacetic acid
Ethyl iodoacetate
Iodoacetamide
References
Alkylating agents
Iodoacetates
Glycol esters | Ethylene bis(iodoacetate) | [
"Chemistry"
] | 94 | [
"Alkylating agents",
"Reagents for organic chemistry"
] |
44,177,166 | https://en.wikipedia.org/wiki/Performance%20Analyzer | Performance Analyzer is a commercial utility software for software performance analysis for x86 or SPARC machines. It has both a graphical user interface and a command line interface. It is available for both Linux and Solaris operating systems. It can profile C, C++, and Java.
Performance Analyzer is available as part of Oracle Developer Studio. It has visualization capabilities, can read out hardware performance counters, thread synchronization, memory allocations and I/O, and specifically supports Java, OpenMP, MPI, and the Solaris kernel.
See also
List of performance analysis tools
Performance analysis
VTune
References
Sun Microsystems software
Profilers | Performance Analyzer | [
"Technology"
] | 133 | [
"Computing stubs",
"Software stubs"
] |
44,181,442 | https://en.wikipedia.org/wiki/Arcadis | Arcadis NV is a global design, engineering and management consulting company based in the Zuidas, Amsterdam, Netherlands. It currently operates in excess of 350 offices across 40 countries. The company is a member of the Next 150 index.
Arcadis was founded as the land reclamation specialist Nederlandsche Heidemaatschappij in 1888. Over the following decades, the firm became involved in various development projects, initially with a rural focus. As a consequence of a restructuring in 1972 that divided the company, it became Heidemij. During 1993, the firm merged with the North American business Geraghty & Miller, resulting in its listing on the Nasdaq index.
During 1997, the company adopted its current name, Arcadis; subsidiaries were similarly rebranded. Since 1990, the company has largely expanded itself via a series of acquisitions and mergers, which have allowed it to both expand its presence in existing markets as well as to enter new ones. It performs design and consultancy services on a wide variety of undertakings. Arcadis (either directly or via subsidiaries) has been involved in several high profile construction projects, including London City Airport and the A2 motorway.
History
19th century: foundation
The company has its origins in the Nederlandsche Heidemaatschappij (English: Association for Wasteland Redevelopment), a land reclamation company founded in the Netherlands in 1888. As such, its original business focus was on the encouragement of agricultural development in the Dutch heather lands.
20th century: domestic, US and Brazil expansion
In the early 20th century the Heidemaatschappij was involved in all aspects of rural development including irrigation and forestry. In 1972, it was decided to heavily restructure the company, resulting in its division into two separate entities, the Association (or KNHM), which continued the company's traditional activities, and Heidemij, which became the commercial arm.
In 1993, the company merged with Geraghty & Miller, granting the new Arcadis a presence in the North American market and an initial listing on the Nasdaq index. Geraghty and Miller, headquartered in Long Island, New York, was subsequently rebranded as Arcadis North America.
Two years later, Heidemij became a listed company on the Next 150 index. During October 1997, the company opted to rebrand itself, changing its name to Arcadis. Two years later, it established a presence in the Brazilian market via the firm's acquisition of Logos Engenharia.
2000s: UK expansion
In June 2005, Axtell Yates Hallett was acquired and became a subsidiary of Arcadis NV, being rebranded as Arcadis UK. AYH was a British quantity surveying firm, founded by Stanley Axtell and his colleagues Messrs Yates and Hallett in the City of London in 1946. Since 1946, Axtell Yates Hallett firm grew steadily and broadened both its service base to include firstly project management and subsequently building surveying and facilities consultancy and its area of operation with the opening of regional and overseas offices in the United Kingdom. Following a period of retrenchment during the economic recession of the beginning of the 1990s, the firm was incorporated as the AYH Partnership in February 1994. One of the firm's last projects was Arsenal F.C.'s Emirates Stadium.
In April 2006, Arcadis acquired Summerfield Robb Clark, a practice in Scotland. Four months later, it also bought Berkeley Consulting, a practice specialising in infrastructure work. Arcadis UK merged with EC Harris on 2 November 2011, after a vote of EC Harris' 183 partners on 31 October 2011. In April 2012, the company acquired Langdon & Seah, an international construction consultancy company.
2010s–2020s: EU and North American expansion
In October 2011, Arcadis acquired EC Harris, an international built asset consultancy firm headquartered in the United Kingdom.
In 2012, Arcadis purchased Langdon & Seah, an Asia-based cost and project management consultancy.
In October 2013, Princess Beatrix of the Netherlands visited Arcadis as part of the celebrations for its 125th anniversary.
In 2014, Arcadis purchased Hyder Consulting, a multi-national advisory and design consultancy specializing in the transport, property, utilities and environmental sectors.
In October 2014, the company acquired Hyder Consulting for £296 million. Hyder Consulting, now an integrated component of Arcadis can trace its roots back to as early as 1739.
In 2014, Arcadis purchased Callison, an international architecture firm based in Seattle, Washington.
In October 2015, a new subsidiary, CallisonRTKL, was formed through the merger of two existing Arcadis subisiaries, Callison and RTKL.
In March 2017, Arcadis announced that its Supervisory Board has nominated Peter Oosterveer as CEO and Chairman of the Arcadis Executive Board.
In 2020, Arcadis acquired Over Morgen, a Dutch development and energy transition consulting firm.
In 2020, Arcadis acquired EAMS Group, a provider of enterprise asset management systems.
In July 2022, Arcadis announced it was acquiring IBI Group, a global architectural and engineering services company based in Canada, to be effective in September 2022.
In October 2022, Arcadis announced CEO Peter Oosterveer’s retirement, and that current Chief Operating Officer Alan Brookes would be nominated as his successor in 2023.
In December 2022, Arcadis acquired DPS Group, an Ireland-based international construction consultancy specializing in life sciences and semiconductor facilities.
Projects
Projects in which Arcadis was involved include:
London City Airport, completed in 1987
Millau Viaduct, France, completed in 2004
Tietê River Project, Brazil, completed in 2015
Skip Spann Connector Bridge, Georgia, completed in 2016
Tunnel section of A2 motorway, Netherlands, completed in 2019
Ten stations on the Doha Metro Gold Line, completed in 2019
Long Beach International Gateway, California, completed in 2020
Port of Calais Breakwater, France, completed in 2020
Six stations on the Sydney Metro City & Southwest, Australia, due to be completed in 2024
Rail systems for Old Oak Common railway station, due to be completed in 2032
Publications
The Arcadis Sustainable Cities Index 2022
2022 Global Construction Disputes Report
International Construction Costs 2022
References
Companies based in Amsterdam
Companies listed on Euronext Amsterdam
Engineering companies of the Netherlands
International engineering consulting firms
Multinational companies headquartered in the Netherlands
Dutch companies established in 1888 | Arcadis | [
"Engineering"
] | 1,323 | [
"Engineering consulting firms",
"International engineering consulting firms"
] |
44,182,173 | https://en.wikipedia.org/wiki/ST%20motif | The ST motif is a commonly occurring feature in proteins and polypeptides. It consists of four or five amino acid residues with either serine or threonine as the first residue (residue i). It is defined by two internal hydrogen bonds. One is between the side chain oxygen of residue i and the main chain NH of residue i + 2 or i + 3; the other is between the main chain oxygen of residue i and the main chain NH of residue i + 3 or i + 4. Two websites are available for finding and examining ST motifs in proteins, Motivated Proteins: and PDBeMotif.
When one of the hydrogen bonds is between the main chain oxygen of residue i and the side chain NH of residue i + 3 the motif incorporates a beta turn. When one of the hydrogen bonds is between the side chain oxygen of residue i and the main chain NH of residue i + 2 the motif incorporates an ST turn.
As with ST turns, a significant proportion of ST motifs occur at the N-terminus of an alpha helix with the serine or threonine as the N cap residue. They have thus often been described as helix capping features.
A related motif is the asx motif which has aspartate or asparagine as the first residue.
Two well conserved threonines at α-helical N-termini occur as ST motifs and form part of the characteristic nucleotide binding sites of SF1 and SF2 type DNA and RNA helicases.
It has been suggested that the sequences SPXX or STXX are frequently found at DNA-binding sites and also that they are recognized as substrates by some protein kinases. Structural studies of polypeptides indicate that such tetrapeptides can adopt the hydrogen bonding pattern of the ST motif.
References
Protein structural motifs | ST motif | [
"Biology"
] | 372 | [
"Protein structural motifs",
"Protein classification"
] |
44,182,725 | https://en.wikipedia.org/wiki/Composite%20Higgs%20models | In particle physics, composite Higgs models (CHM) are speculative extensions of the Standard Model (SM) where the Higgs boson is a bound state of new strong interactions. These scenarios are models for physics beyond the SM presently tested at the Large Hadron Collider (LHC) in Geneva.
In all composite Higgs models the Higgs boson is not an elementary particle (or point-like) but has finite size, perhaps around 10−18 meters. This dimension may be related to the Fermi scale (100 GeV) that determines the strength of the weak interactions such as in β-decay, but it could be significantly smaller. Microscopically the composite Higgs will be made of smaller constituents in the same way as nuclei are made of protons and neutrons.
History
Often referred to as "natural" composite Higgs models, CHMs are constructions that attempt to alleviate fine-tuning or "naturalness" problem of the Standard Model.
These typically engineer the Higgs boson as a naturally light pseudo-Goldstone boson or Nambu-Goldstone field, in analogy to the pion (or more precisely, like the K-mesons) in QCD. These ideas were introduced by Georgi and Kaplan as a clever variation on technicolor theories to allow for the presence of a physical low mass Higgs boson.
These are forerunners of Little Higgs theories.
In parallel, early composite Higgs models arose from the heavy top quark and its renormalization group infrared fixed point, which implies a strong coupling of the Higgs to top quarks at high energies.
This formed the basis of top quark condensation theories of electroweak symmetry breaking in which the Higgs boson is composite at extremely short distance scales, composed of a pair of top and anti-top quarks. This was described by Yoichiro Nambu and subsequently developed by Miransky, Tanabashi, and Yamawaki
and Bardeen, Hill, and Lindner,
who connected the theory to the renormalization group and improved its predictions.
While these ideas are still compelling, they suffer from a "naturalness problem", a large degree of fine-tuning.
To remedy the fine tuning problem, Chivukula, Dobrescu, Georgi and Hill introduced the "Top See-Saw" model in which the composite scale is reduced to the several TeV (trillion electron volts, the energy scale of the LHC). A more recent version of the Top Seesaw model of Dobrescu and Cheng has an acceptable
light composite Higgs boson.
Top Seesaw models have a nice geometric interpretation in theories of extra dimensions, which
is most easily seen via dimensional deconstruction (the latter approach does away with the technical details of the geometry of the extra spatial dimension and gives a renormalizable D-4 field theory). These schemes also anticipate "partial compositeness".
These models are discussed in the extensive review of strong dynamical theories of Hill and Simmons.
CHMs typically predict new particles with mass around a TeV (or tens of TeV as in the Little Higgs schemes) that are excitations or ingredients of the composite Higgs, analogous to the resonances in nuclear physics. The new particles could be produced and detected in collider experiments if the energy of the collision exceeds their mass or could produce deviations from the SM predictions in "low energy observables" – results of experiments at lower energies. Within the most compelling scenarios each Standard Model particle has a partner with equal quantum numbers but heavier mass. For example, the photon, W and Z bosons have heavy replicas with mass determined by the compositeness scale, expected around 1 TeV.
Though naturalness requires that new particles exist with mass around a TeV which could be discovered at LHC or future experiments, nonetheless as of 2018, no direct or indirect signs that the Higgs or other SM particles are composite has been detected.
From the LHC discovery of 2012, it is known that there exists a physical Higgs boson
(a weak iso-doublet) that condenses to break the electro-weak symmetry. This differs from the prediction ordinary technicolor theories where new strong dynamics directly breaks the electro-weak symmetry without the need of a physical Higgs boson.
The CHM proposed by Georgi and Kaplan was based on known gauge theory dynamics that produces the Higgs doublet as a Goldstone boson. It was later realized, as with the case of Top Seesaw models described above, that this can naturally arise in five-dimensional theories, such as the Randall–Sundrum scenario or by dimensional deconstruction. These scenarios can also be realized in hypothetical strongly coupled conformal field theories (CFT) and the AdS-CFT correspondence. This spurred activity in the field. At first the Higgs was a generic scalar bound state. In the influential work the Higgs as a Goldstone boson was realized in CFTs. Detailed phenomenological studies showed that within this framework agreement with experimental data can be obtained with a mild tuning of parameters.
The more recent work on the holographic realization of CHM, which is based on the AdS/QCD correspondence, provided an explicit realization of the strongly coupled sector of CHM and the computation of meson masses, decay constants and the top-partner mass.
Examples
CHM can be characterized by the mass (m) of the lightest new particles and their coupling (g). The latter is expected to be larger than the SM couplings for consistency. Various realizations of CHM exist that differ for the mechanism that generates the Higgs doublet. Broadly they can be divided in two categories:
Higgs is a generic bound state of strong dynamics.
Higgs is a Goldstone boson of spontaneous symmetry breaking
In both cases the electro-weak symmetry is broken by the condensation of a Higgs scalar doublet. In the first type of scenario there is no a priori reason why the Higgs boson is lighter than the other composite states and moreover larger deviations from the SM are expected.
Higgs as Goldstone boson
These are essentially Little Higgs theories.
In this scenario the existence of the Higgs boson follows from the symmetries of the theory. This allows to explain why this particle is lighter than the rest of the composite particles whose mass is expected from direct and indirect tests to be around a TeV or higher. It is assumed that the composite sector has a global symmetry spontaneously broken to a subgroup where and are compact Lie groups. Contrary to technicolor models the unbroken symmetry must contain the SM electro-weak group According to Goldstone's theorem the spontaneous breaking of a global symmetry produces massless scalar particles known as Goldstone bosons. By appropriately choosing the global symmetries it is possible to have Goldstone bosons that correspond to the Higgs doublet in the SM. This can be done in a variety of ways
and is completely determined by the symmetries. In particular group theory determines the quantum numbers of the Goldstone bosons. From the decomposition of the adjoint representation one finds
where is the representation of the Goldstone bosons under The phenomenological request that a Higgs doublet exists selects the possible symmetries. Typical example is the pattern
that contains a single Higgs doublet as a Goldstone boson.
The physics of the Higgs as a Goldstone boson is strongly constrained by the symmetries and determined by the symmetry breaking scale that controls their interactions. An approximate relation exists between mass and coupling of the composite states,
In CHM one finds that deviations from the SM are proportional to
where is the electro-weak vacuum expectation value. By construction these models approximate the SM to arbitrary precision if is sufficiently small. For example, for the model above with global symmetry the coupling of the Higgs to W and Z bosons is modified as
Phenomenological studies suggest and thus at least a factor of a few larger than . However the tuning of parameters required to achieve is inversely proportional to so that viable scenarios require some degree of tuning.
Goldstone bosons generated from the spontaneous breaking of an exact global symmetry are exactly massless. Therefore, if the Higgs boson is a Goldstone boson the global symmetry cannot be exact. In CHM the Higgs potential is generated by effects that explicitly break the global symmetry Minimally these are the SM Yukawa and gauge couplings that cannot respect the global symmetry but other effects can also exist. The top coupling is expected to give a dominant contribution to the Higgs potential as this is the largest coupling in the SM. In the simplest models one finds a correlation between the Higgs mass and the mass of the top partners,
In models with as suggested by naturalness this indicates fermionic resonances with mass around Spin-1 resonances are expected to be somewhat heavier. This is within the reach of future collider experiments.
Partial compositeness
One ingredient of modern CHM is the hypothesis of partial compositeness proposed by D.B. Kaplan. This is similar to a (deconstructed) extra dimension, in which every Standard Model particle has a heavy partner(s) that can mix with it. In practice, the SM particles are linear combinations of elementary and composite states:
where denotes the mixing angle.
Partial compositeness is naturally realized in the gauge sector, where an analogous phenomenon happens quantum chromodynamics and is known as – mixing (after the photon and rho meson – two particles with identical quantum numbers which engage in similar intermingling). For fermions it is an assumption that in particular requires the existence of heavy fermions with equal quantum numbers to S.M. quarks and leptons. These interact with the Higgs through the mixing. One schematically finds the formula for the S.M. fermion masses,
where subscripts L and R mark the left and right mixings, and is a composite sector coupling.
The composite particles are multiplets of the unbroken symmetry H. For phenomenological reasons this should contain the custodial symmetry SU(2)×SU(2) extending the electro-weak symmetry SU(2)×U(1). Composite fermions often belong to representations larger than the SM particles. For example, a strongly motivated representation for left-handed fermions is the (2,2) that contains particles with exotic electric charge or with special experimental signatures.
Partial compositeness ameliorates the phenomenology of CHM providing a logic why no deviations from the S.M. have been measured so far. In the so-called anarchic scenarios the hierarchies of S.M. fermion masses are generated through the hierarchies of mixings and anarchic composite sector couplings. The light fermions are almost elementary while the third generation is strongly or entirely composite. This leads to a structural suppression of all effects that involve first two generations that are the most precisely measured. In particular flavor transitions and corrections to electro-weak observables are suppressed. Other scenarios are also possible with different phenomenology.
Experiments
The main experimental signatures of CHM are:
New heavy partners of Standard Model particles, with SM quantum numbers and masses around a TeV
Modified SM couplings
New contributions to flavor observables
Supersymmetric models also predict that every Standard Model particle will have a heavier partner. However, in supersymmetry the partners have a different spin: they are bosons if the SM particle is a fermion, and vice versa. In composite Higgs models the partners have the same spin as the SM particles.
All the deviations from the SM are controlled by the tuning parameter ξ. The mixing of the SM particles determines the coupling with the known particles of the SM. The detailed phenomenology depends strongly on the flavor assumptions and is in general model-dependent. The Higgs and the top quark typically have the largest coupling to the new particles. For this reason third generation partners are the most easy to produce and top physics has the largest deviations from the SM. Top partners have also special importance given their role in the naturalness of the theory.
After the first run of the LHC direct experimental searches exclude third generation fermionic resonances up to 800 GeV. Bounds on gluon resonances are in the multi-TeV range and somewhat weaker bounds exist for electro-weak resonances.
Deviations from the SM couplings is proportional to the degree of compositeness of the particles. For this reason the largest departures from the SM predictions are expected for the third generation quarks and Higgs couplings. The first have been measured with per mille precision by the LEP experiment. After the first run of the LHC the couplings of the Higgs with fermions and gauge bosons agree with the SM with a precision around 20%. These results pose some tension for CHM but are compatible with a compositeness scale f~TeV.
The hypothesis of partial compositeness allows to suppress flavor violation beyond the SM that is severely constrained experimentally. Nevertheless, within anarchic scenarios sizable deviations from the SM predictions exist in several observables. Particularly constrained is CP violation in the Kaon system and lepton flavor violation for example the rare decay μ->eγ. Overall flavor physics suggests the strongest indirect bounds on anarchic scenarios. This tension can be avoided with different flavor assumptions.
Summary
The nature of the Higgs boson remains a conundrum. Philosophically, the Higgs boson is either
a composite state, built of more fundamental constituents, or it is connected to other states in nature by a symmetry such as supersymmetry (or some blend of these concepts). So far there is no evidence of either compositeness or supersymmetry.
The fact that nature provides a single (weak isodoublet) scalar field that ostensibly uniquely generates fundamental particle masses has yet to be explained.
At present, we have no idea what mass / energy scale will reveal additional information about the Higgs boson that may shed useful light on these issues. While theorists remain busy concocting explanations, this limited insight poses a major challenge to experimental particle physics: We have no clear idea whether feasible accelerators might provide new useful information beyond the S.M. It is hoped that upgrades in luminosity and energy at the LHC may possibly provide new clues.
See also
Alternatives to the Standard Higgs Model
Two-Higgs-doublet model
Preon
References
Physics beyond the Standard Model
Hypothetical composite particles | Composite Higgs models | [
"Physics"
] | 3,017 | [
"Unsolved problems in physics",
"Particle physics",
"Physics beyond the Standard Model"
] |
44,182,806 | https://en.wikipedia.org/wiki/Larry%20Samuelson | Larry Samuelson (born April 2, 1953) is the A. Douglas Melamed Professor of Economics at Yale University and one of the faculty of the Cowles Foundation of Yale University.
Samuelson earned his B.A. in economics/political science from the University of Illinois in 1974. He continued on with the University of Illinois for both his master's degree in 1977 and his PhD in 1978—both in economics.
He has previously held faculty positions at the University of Florida, Syracuse University, Penn State and the University of Wisconsin.
He has made significant contributions to microeconomic theory and game theory. Areas of specialization include the theory of repeated games and the evolutionary foundations of economic behavior.
Samuelson has served on the editorial boards of Games and Economic Behavior, the International Journal of Game Theory, Economic Theory, the Journal of Economic Theory, Theoretical Economics, the Journal of Economic Literature, and Econometrica. He has served as a co-editor of Econometrica and the American Economic Review.
References
External links
1953 births
Living people
Yale University faculty
University of Wisconsin–Madison faculty
Pennsylvania State University faculty
Syracuse University faculty
University of Illinois Urbana-Champaign alumni
Fellows of the Econometric Society
Game theorists
Fellows of the American Academy of Arts and Sciences | Larry Samuelson | [
"Mathematics"
] | 253 | [
"Game theorists",
"Game theory"
] |
44,183,693 | https://en.wikipedia.org/wiki/Elaine%20Oran | Elaine Surick Oran (born April 16, 1946) is an American physical scientist and is considered a world authority on numerical methods for large-scale simulation of physical systems. She has pioneered computational technology to solve complex reactive flow problems, unifying concepts from science, mathematics, engineering, and computer science in a new methodology. An incredibly diverse range of phenomena can be modeled and better understood using her techniques for numerical simulation of fluid flows, ranging from the tightly grouped movements of fish in Earth's oceans to the explosions of far-flung supernovae in space. Her work has contributed significantly to the advancement of the engineering profession.
Education
Elaine Surick is the daughter of Herman E. Surick and the stepdaughter of Doris Luterman-Surick. She is married to Daniel Oran.
Elaine Surick attended school in Philadelphia, Pennsylvania. Bryn Mawr College awarded her a bachelor's degree in both physics and chemistry (1966). She then attended Yale University, where she received a master's degree from the department of physics (1968) and a Ph.D. from the department of engineering and applied sciences (1972).
U.S. Naval Research Lab
Elaine Oran joined the Plasma Physics Division at United States Naval Research Laboratory (NRL) in 1972. In 1978, she joined the Laboratory for Computational Physics. She worked to start the Center for Reactive Flow and Dynamical Systems, and became its head. In 1988, she became the senior scientist for reactive flow physics.
She has done significant theoretical and computational research on complex dynamic systems' fluid and molecular properties. Her team has created many numerical algorithms and computerized models for accurate numerical simulation of reactive flows. Because reactive flows occur in a broad range of important phenomena, Oran's work has enabled other investigators to examine and describe many previously unexplained reactive flow dynamics.
Reactive flows can involve gases, liquids, solids, or combinations thereof. As these move through space and over time, they may change chemically. Reactive flow problems often involve multiple processes interacting simultaneously. Identifying the boundary conditions where states of matter react and how they interact is important in modeling reactive flows. Physical processes involved in reactive flows include species reactions, diffusive transport, radiative transport, convection, and wave-like properties, some or all of which may be modeled to address a particular problem. Modelling of complex reactive flows has applications in a wide variety of areas including aerodynamics, hydrodynamics, microfluidics, chemical kinetics, chemical process modeling (involving advective and diffusive transport processes as well as chemical kinetics) and combustion-related flame and detonation phenomena.
Reactive flow modeling can be applied to solar and stellar astrophysics to study novae, star formation, and cosmology. It can model mixing in Earth's atmosphere, rarefied gas flow during atmospheric reentry, torpedo launches in the Earth's oceans, the spread of fires in cities and forests, and the behavior of car engines and chemical lasers.
Oran has applied simulation methods to various issues at the Naval Research Lab. She has helped to design biosensors, propulsion systems for rockets and jets, and space and planetary exploration vehicles. She has studied the fundamental physics of combustion processes, applying flow models to flames, detonations, and the conditions underlying the transition to denotation. Her work has supported the safe storage of hydrogen fuels and other energetic materials.
Aerospace engineering
She is currently a professor at Texas A&M University. She worked at the department of aerospace engineering at the University of Maryland as a Glenn L. Martin Institute Professor of Engineering from 2013 to 2019. She continues to serve as an emeritus scientist at the U.S. Naval Research Laboratory and is an adjunct professor at the University of Michigan and a visiting professor at Leeds University. She is also a senior visiting professor in the Institute for Advanced Study at Hong Kong University of Science and Technology and a distinguished visiting professor at Tsinghua University.
Publications
She has published extensively in journals and has written a textbook, Numerical Simulation of Reactive Flow (1987, 2005), which is reported to be the most frequently used textbook on the topic.
Awards and honors
Among many other awards and honors, Elaine Oran is an Honorary Fellow of the American Institute of Aeronautics and Astronautics (AIAA), "the highest distinction conferred by AIAA, … granted to preeminent individuals who have had long and highly contributory careers in aerospace, and embody the highest possible standards in aeronautics and astronautics." She is a Fellow of the American Academy of Arts and Sciences, National Academy of Engineering and an inaugural Fellow of The Combustion Institute.
Other awards, honors, and honorary memberships include, but are not limited to, the following:
Awards
Hoyt C. Hottel Keynote lecture at the International Combustion Symposium, 2014
Fluid Dynamics Prize (APS), 2013, from the American Physical Society (APS)
Presidential Rank Award for Distinguished Senior Professionals, from the United States Government, for exceptional long-term accomplishments, 2007
Society of Women Engineers Achievement Award, 2006
Dryden Lectureship in Research Award from American Institute of Aeronautics and Astronautics, 2002
Women in Technology International (WITI) Hall of Fame, 2002
Combustion Institute's Zeldovich Gold Medal, 2000, for "outstanding contributions to the theory of combustion and detonations."
Oppenheim Prize, 1999, given by the Institute for the Dynamics of Energetic and Reactive Systems, for "outstanding contributions to the theory of the dynamics of explosions and reactive systems."
Arthur S. Flemming Award, 1979
Honorary degrees
Doctor of Science, honoris causa (DSc) from the University of Leeds, conferred 15 July 2010
Docteur Honoris Causa from the École Centrale de Lyon, 2006
Docteur Honoris Causa, Institut National des Sciences Appliquées Rouen, conferred on 3 April 2015.
Memberships
Elected an international fellow of the Royal Academy of Engineering, 2024
Fellow, American Academy of Arts and Sciences, 2018
Fellow, The Combustion Institute, 2018
Member, Committee on Human Rights, National Academies of Science, Engineering and Medicine
Fellow of the American Society of Mechanical Engineers (ASME), 2012
Advisory Board, Acta Mechanica Sinica, 2011–Present
Honorary Fellow of the American Institute of Aeronautics and Astronautics (AIAA), 2011
Fellow of the Society for Industrial and Applied Mathematics (SIAM), 2009 (charter member)
Member of the National Academy of Engineering, 2003, "the highest honor to which any aerospace engineer can aspire."
Fellowship in the American Physical Society (APS), 1993, "for innovations using cutting edge computers to model and explain important physical mechanisms involving fluid dynamics, chemistry, and nonequilibrium material properties in complex reacting flows ranging from laboratory to astrophysical systems."
Fellow of the American Institute of Aeronautics and Astronautics (AIAA), 1990
Society of Women Engineers
References
External links
Oral history interview transcript with Elaine Oran on 18 June 2021, American Institute of Physics, Niels Bohr Library & Archives
Living people
American women computer scientists
American computer scientists
American women physicists
21st-century American physicists
University of Maryland, College Park alumni
Bryn Mawr College alumni
Yale University alumni
Fellows of the American Society of Mechanical Engineers
Fellows of the Society for Industrial and Applied Mathematics
University of Maryland, College Park faculty
University of Michigan faculty
Fellows of the American Institute of Aeronautics and Astronautics
Fellows of the Combustion Institute
1946 births
American women academics
21st-century American women scientists
Fellows of the Royal Academy of Engineering
Female fellows of the Royal Academy of Engineering | Elaine Oran | [
"Chemistry"
] | 1,536 | [
"Fellows of the Combustion Institute",
"Combustion"
] |
44,184,824 | https://en.wikipedia.org/wiki/Aba%20Andam | Professor Aba A. Bentil Andam (born 1948) is a Ghanaian particle physicist who was President of the Ghana Academy of Arts and Sciences from 2017 to 2019. She is the first Ghanaian female physicist.
Early life and education
Aba A. Bentil Andam was born in Ghana in 1948 in Ajumako Kokoben. She had her secondary education at Mfantsiman Senior High School. She completed her undergraduate degree at the University of Cape Coast in Ghana (1969-1973), where she majored in physics and minored in mathematics. She sought further education in Britain where she earned a master's degree from the University of Birmingham (1976-1977) and a Ph.D. in Cosmic Radiation Physics from Durham University in the UK (1978-1981). At the University of Cape Coast and Durham University, she was the only woman physicist in the department during her time there.
Career
In 1986, she became a chartered physicist and full member of the Institute of Physics. In addition to her scientific degrees, she is fluent in French, and has a number of different French language qualifications, including the Diplome de Langue d'Alliance Francaise de Paris; the French Proficiency Certificate of Ghana Institute of Languages; and the Certificate of Translation, Alliance Francaise de Paris.
In 1986 and 1987 she studied charmed mesons at the German research station DESY (Deutsches Elektronen-Synchrotron). Later, her research focused on radon and surveyed human exposure levels of the radioactive gas in Ghana. Andam was interested in determining how much radiation from radon Ghanaians were exposed to, and how she can reduce radon radiation exposure. She is also interested in radiation-based safety measures, such as working out a safety standard for X-ray scans.
Beginning in 1987, she participated in the Ghana Science Clinics for Girls, where female students and scientists met. The scientists then acted as role models to the students. These clinics led to increased performance in the students who took part, and the retention rates from primary to university considerably increased. Andam is passionate about sharing her love of science with young women and encouraging them to take up science.
Andam has been a professor at the Kwame Nkrumah University of Science and Technology since 1981. She has headed the physics department since the mid 2000s, and from 2005 has been the WILKADO Chair of Science and Technology. She conducts research in applied nuclear physics at Kumasi's Nuclear Research Laboratory. She also was a part-time lecturer at the University of Cape Coast. She has served as the UNESCO chair of the Women in Science and Technology in Africa's West African region between 1996 and 2002.
Prof. Aba Andam has been a member of the National Council for Tertiary Education and has been honored with awards from various entities including Obaa Mbo, a television program, as well as The Women of Excellence Award from the Ministry of Gender. Additionally, recognition has been bestowed upon her by the Council for Scientific and Industrial Research (CSIR) and the Chartered Institute of Supply Chain Management of Ghana.
Since September 2019, she has held the position of President at the Ghana Institute of Physics. She has also served as a member of the Commission on Physics and Development (C13) of the International Union of Pure and Applied Physics (IUPAP) since 2018. Additionally, she has been a member of the Committee on the proposed African Light Source since 2020. In her extensive career, she has held key roles such as Foundation Chairman for the Council of the University of Energy and Natural Resources, Ghana (2012-2015), and Foundation Chairman for the Council of Koforidua Polytechnic, Ghana (1997-2002). Furthermore, she has contributed significantly as a member of the Governing Board of the Ghana Atomic Energy Commission (1997-2001, then 2002-2008). She is also recognized as a Foundation Member of the First IUPAP Working Group on Women in Physics and has led the Ghana Team of the IUPAP Conferences on Women in Physics to date.
Honours and recognition
She is a fellow of various different scientific organizations namely; The World Innovation Foundation (from 2002), Ghana Academy of Arts and Sciences (from 2003), and the Institute of Physics (from 2004). She was the President of the Ghana Academy of Arts and Sciences (2017-2019), the second woman to hold this position.
Personal life
She was married to Professor Kwesi Akwansah Andam who was a Civil Engineer, an academician and a former Vice Chancellor. They had four children.
References
1948 births
Living people
Alumni of the University of Birmingham
Ghanaian physicists
Academic staff of Kwame Nkrumah University of Science and Technology
Particle physicists
University of Cape Coast alumni
Fellows of the Ghana Academy of Arts and Sciences
Alumni of Durham University Graduate Society
20th-century Ghanaian women
People from Central Region (Ghana)
Mfantsiman Girls' Secondary School alumni
20th-century Ghanaian scientists
People associated with IUPAP | Aba Andam | [
"Physics"
] | 1,005 | [
"Particle physicists",
"Particle physics"
] |
44,184,942 | https://en.wikipedia.org/wiki/Austin%20L.%20Wahrhaftig | Austin Levy Wahrhaftig (May 5, 1917 – November 11, 1997) was an American chemist and mass spectrometrist known for his development of the quasi-equilibrium theory of fragmentation of molecular ions. The Wahrhaftig diagram that illustrates the relationship between internal energy and unimolecular ion decomposition is named after him.
Early life and education
Wahrhaftig was born in Sacramento, California, where he attended grade school, high school, and two years at Sacramento Junior College. He attended the University of California, Berkeley where he did undergraduate research with Joel Hildebrand and received an A.B. in chemistry in 1938.
He went to graduate school at the California Institute of Technology where he worked under Richard M. Badger and Verner Schomaker . He received his Ph.D. in 1941. He was a research fellow at Caltech from 1941 to 1945.
He then worked at the Wright Air Development Center in Pasadena, California, and as a University Fellow at the Ohio State University with Herrick L. Johnston.
Academic career
Wahrhaftig joined the faculty at the Chemistry Department at the University of Utah in 1947 where he rose through the ranks and spent the rest of his career. He retired to become an emeritus professor in 1987.
References
Further reading
1917 births
1997 deaths
20th-century American chemists
Mass spectrometrists
University of California, Berkeley alumni
California Institute of Technology alumni
California Institute of Technology fellows
University of Utah faculty | Austin L. Wahrhaftig | [
"Physics",
"Chemistry"
] | 299 | [
"Biochemists",
"Mass spectrometry",
"Spectrum (physical sciences)",
"Mass spectrometrists"
] |
44,185,220 | https://en.wikipedia.org/wiki/Wilf%20equivalence | In the study of permutations and permutation patterns, Wilf equivalence is an equivalence relation on permutation classes.
Two permutation classes are Wilf equivalent when they have the same numbers of permutations of each possible length, or equivalently if they have the same generating functions. The equivalence classes for Wilf equivalence are called Wilf classes; they are the combinatorial classes of permutation classes. The counting functions and Wilf equivalences among many specific permutation classes are known.
Wilf equivalence may also be described for individual permutations rather than permutation classes. In this context, two permutations are said to be Wilf equivalent if the principal permutation classes formed by forbidding them are Wilf equivalent.
References
Enumerative combinatorics
Permutation patterns
Equivalence (mathematics) | Wilf equivalence | [
"Mathematics"
] | 173 | [
"Enumerative combinatorics",
"Combinatorics"
] |
44,187,456 | https://en.wikipedia.org/wiki/Tactical%20urbanism | Tactical urbanism, also commonly referred to as guerrilla urbanism, pop-up urbanism, city repair, D.I.Y. urbanism, planning-by-doing, urban acupuncture, and urban prototyping, is a low-cost, temporary change to the built environment, usually in cities, intended to improve local neighbourhoods and city gathering places.
Tactical urbanism is often citizen-led but can also be initiated by government entities. Community-led temporary installations are often intended to pressure government agencies into installing a more permanent or expensive version of the improvement.
Terminology
The term was popularized around 2010 to refer to a range of existing techniques. The Street Plans Collaborative defines "tactical urbanism" as an approach to urban change that features the following five characteristics:
A deliberate, phased approach to instigating change;
The offering of local solutions for local planning challenges;
Short-term commitment as a first step towards longer-term change;
Lower-risk, with potentially high rewards; and
The development of social capital between citizens and the building of organizational capacity between public and private institutions, non-profits, and their constituents.
While the 1984 English translation of The Practice of Everyday Life by French author Michel de Certeau used the term tactical urbanism, this was in reference to events occurring in Paris in 1968; the "tactical urbanism" that Certeau described was in opposition to "strategic urbanism", which modern concepts of tactical urbanism tend not to distinguish. The modern sense of the term is attributed to New York-based urban planner Mike Lydon.
The Project for Public Spaces uses the phrase "Lighter, Quicker, Cheaper", coined by urban designer Eric Reynolds, to describe the same basic approach expressed by tactical urbanism.
Origin
The tactical urbanist movement takes inspiration from urban experiments including Ciclovía, Paris-Plages, and the introduction of plazas and pedestrian malls in New York City during the tenure of Janette Sadik-Khan as Commissioner of the New York City Department of Transportation.
Tactical urbanism formally emerged as a movement following a meeting of the Next Generation of New Urbanist (CNU NextGen) group in November 2010 in New Orleans. A driving force of the movement is to put the onus back on individuals to take personal responsibility in creating sustainable buildings, streets, neighborhoods, and cities. Following the meeting, an open-source project called Tactical Urbanism: Short TermAction | Long Term Change was developed by a group from NextGen to define tactical urbanism and to promote various interventions to improve urban design and promote positive change in neighbourhoods and communities.
Examples
Honolulu, Hawaii has some of the highest pedestrian fatality rates in the United States (Wong 2012). Many of their busiest intersections reflect city standards from years past without modification as the quantity of vehicular traffic and associated speeds have changed dramatically. Some residents chose to take a stand in 2014. Within the crosswalk of one of these busy intersections, residents altered the crosswalk lines so that they spelled out "Aloha," the traditional Hawaiian salutation. While the perpetrators sought to introduce a level of humanity to the dangerous location, city officials stated that the change was a "deviation from the standard."
In spring of 2016, the city of Chicago posted unique "no right turn" signage to an intersection. To call attention to this new condition, an unknown person installed two small planter boxes within the crosswalk with flowering plants. Many responded positively while local businesses expressed concern for the traffic pattern change and its effect on their business.
Types of interventions
Tactical urbanism projects vary significantly in scope, size, budget, legality, and support. Projects often begin as grassroots interventions and spread to other cities, and are in some cases later adopted by municipal governments as best practices. Some common interventions are listed below:
Improving public spaces
Better block initiatives: Temporarily transforming retail streets using cheap or donated materials and volunteers. Spaces are transformed by introducing food carts, sidewalk tables, temporary bike lanes and narrowing of streets;
Chair bombing: The act of removing salvageable materials and using it to build public seating. The chairs are placed in areas that either are quiet or lack comfortable places to sit.
Food carts/trucks: Food carts and trucks are used to attract people to underused public spaces and offer small business opportunities for entrepreneurs;
Open streets: To temporarily provide safe spaces for walking, bicycling, skating, and social activities; promote local economic development; and raise awareness about the impact of cars in urban spaces. "Open Streets" is an anglicized term for the South American 'Ciclovia', which originated in Bogota
Park(ing) Day: An annual event where on street parking is converted into park-like spaces. Park(ing) Day was launched in 2005 by Rebar art and design studio;
Pavement To Plazas: Popularized in New York City, Pavement to Plazas involve converting space on streets to usable public space. The closure of Times Square to vehicular traffic, and its low-cost conversion to a pedestrian plaza, is a primary example of a pavement plaza;
Pop-up cafes: Temporary patios or terraces built in parking spots to provide overflow seating for a nearby cafe or for passersby. Most common in cities where sidewalks are narrow and where there otherwise is not room for outdoor sitting or eating areas;
Pop-up parks: Temporary or permanent transformations of underused spaces into community gathering areas through beautification;
Pop-up retail: Temporary retail stores that are set up in vacant stores or property.
Infrastructure
Crosswalk painting: Guerrilla crosswalks are zebra crossings painted by the community on roadways and at intersections where the city government has failed to provide a marked pedestrian crossing;
Practical walkways: Desire paths are footpaths or other paths that form via natural use rather than paths designed for use by humans in urban environments. Some of these paths are later improved or paved to offer a more practical route to a particular destination.
Protected bike lanes: Pop-up bicycle lanes are usually done by placing potted plants or other physical barriers to make painted bike lanes feel safer. Sometimes there is no pre-existing bike lane, and the physical protection is the only delineator.
Removal
De-fencing: The act of removing unnecessary fences to break down barriers between neighbours, beautify communities, and encourage community building;
Depaving: The act of removing unnecessary pavement to transform driveways and parking into green space so that rainwater can be absorbed and neighbourhoods beautified;
Sabotaging hostile architecture: The act of obstructing, defacing, or removing hostile architecture, usually anti-homeless spikes or armrests, to undermine their intended effects, often to protest anti-homelessness legislation. These actions in particular are often considered acts of vandalism.
Nature
Guerrilla gardening: Cultivating land that the gardeners do not have the legal rights to utilize, such as abandoned sites, areas not being cared for, or private property;
Guerrilla grafting: Grafting fruitbearing branches onto sterile street trees to make an edible city.
See also
Road diet
Sneckdown
Street reclamation
Urban Interventionism
References
Further reading
The Street Plans Collaborative, Inc. (dba Street Plans) in collaboration with Ciudad Emergente and Codesign studio, produces a series of free tactical urbanism e-books. Volumes 1 and 2 focus on North American case studies, Volume 3 is a Spanish-language guide to Latin American projects, and Volume 4 covers Australia and New Zealand, including responses to the 2011 Christchurch earthquake.
Street Plans' Mike Lydon and Anthony Garcia published a tactical urbanism book in March 2015.
New Urbanism
Urban design
Environmentalism
Sustainable transport
Sustainable urban planning
Urban planning
Urban studies and planning terminology
Cultural activism | Tactical urbanism | [
"Physics",
"Engineering"
] | 1,565 | [
"Physical systems",
"Transport",
"Sustainable transport",
"Urban planning",
"Architecture"
] |
44,188,210 | https://en.wikipedia.org/wiki/Filorexant | Filorexant (, ; developmental code name MK-6096) is an orexin antagonist which was under development by Merck for the treatment of insomnia, depression, diabetic neuropathy, and migraine. It is a dual antagonist of the orexin OX1 and OX2 receptors. It has a relatively short elimination half-life of 3 to 6hours. However, it dissociates slowly from the orexin receptors and may thereby have a longer duration. Possibly in relation to this, filorexant shows next-day somnolence similarly to suvorexant. In phase 2 clinical trials, filorexant was found to be effective in the treatment of insomnia, but was not effective in the treatment of major depressive disorder, painful diabetic neuropathy, or migraine. , filorexant was no longer listed on Merck's online development pipeline and hence development of the drug appears to have been discontinued. Development of filorexant may have been discontinued due to lack of differentiation from suvorexant (which was also developed by Merck).
See also
List of investigational sleep drugs
References
External links
Filorexant - AdisInsight
Abandoned drugs
Orexin antagonists
Piperidines
Pyridines
Pyrimidines
Sedatives
Organofluorides | Filorexant | [
"Chemistry"
] | 282 | [
"Drug safety",
"Abandoned drugs"
] |
67,068,617 | https://en.wikipedia.org/wiki/Collection%20of%20Internet%20Connection%20Records | , collection of Internet Connection Records is being secretly trialled by two major British ISPs as part of a technical trial for mass surveillance under the Investigatory Powers Act 2016. The Home Office and National Crime Agency are also participating in the trial.
"Internet Connection Records" is a generic term for metadata records of UK Internet users' Internet access patterns. Data collected may include who they are, what sites they connected to and when, and what quantity of data was transferred, but does not include the data content of the transmissions. While the participants have been kept secret, the existence of the trial has been confirmed by the Investigatory Powers Commissioner’s Office.
See also
Mass surveillance in the United Kingdom
NetFlow
Pen register
Traffic analysis
References
Government databases in the United Kingdom
Internet in the United Kingdom
Mass surveillance in the United Kingdom
Surveillance databases
Metadata | Collection of Internet Connection Records | [
"Technology"
] | 167 | [
"Metadata",
"Data"
] |
67,069,669 | https://en.wikipedia.org/wiki/Gangs%20Matrix | The Gangs Matrix, also known as the Gangs Violence Matrix, is a database of alleged street gang members created by the Metropolitan Police Service in 2012. It has been criticised for its use of circumstantial evidence and disproportionate targeting of young black men.
A 2018 investigation by the Information Commissioner's Office found that the use of the Gangs Matrix at that time was in breach of data protection laws, and issued an enforcement notice to bring the operation of the system in line with the law. The enforcement notice was lifted in 2021.
In 2022, the MPS announced that it had removed more than 1000 people, representing over 65% of the entries in the database, on the basis that they referred to people who posed no threat of violence.
References
Metropolitan Police
Government databases in the United Kingdom
Government by algorithm
Law enforcement databases | Gangs Matrix | [
"Engineering"
] | 170 | [
"Government by algorithm",
"Automation"
] |
67,070,217 | https://en.wikipedia.org/wiki/Lampenflora | Lampenflora, also known in English as lamp-flora or lamp flora are autotrophic lifeforms present in natural or artificial caves associated with permanently installed lighting. Lampenflora are a problem with respect to the conservation of cave features, artworks, and fauna, and consequently their presence in caves can be referred to by the terms green sickness and la maladie verte.
Etymology
The term "lampenflora" has come to English from German. It was coined by botanist Klaus Dobat in the 1960s, and just means "lamp flora".
Taxa found in lampenflora
So far the following types of lampenflora have been described:
cyanobacteria
algae – Chlorophyceae, golden algae (Chrysophyceae), diatoms (Bacillariophyceae)
non-vascular plants – Marchantiophyta (Marchantiophyta), moss (Bryophyta)
ferns – Species of the genera Asplenium (spleenworts), Cystopteris (bladder ferns), Adiantum (maidenhair ferns), etc.
flowering plants – alternate-leaved golden-saxifrage (Chrysosplenium alternifolium); black elder (Sambucus nigra) from the moschatel (Adoxaceae) family has been growing since in the Lurgrotte near Peggau in Styria.
Fungi and roots growing into caves, as well as plants growing in naturally illuminated areas, are not lampenflora.
Development
The requirements for the development of lampenflora are sufficient (artificial) light and moisture. An increase in nutrient content (e.g. fertilizer usage on land above the cave) or heat (e.g. incandescent lighting) may lead to an increase in lampenflora.
The germs, seeds or spores can get brought into the cave by air, water, animals or people.
In the aphotic (lightless) part of caves, short-term growth of photosynthetic plants is possible thanks to the seed's nutritive tissue. After this is consumed, the plant dies.
Lampenflora as a problem
Lampenflora can cause various problems: Since lampenflora changes the appearance of show caves, it can give visitors wrong impressions of natural caves. It does not exist in caves not developed for humans. The weak acids excreted by lampenflora can also cause damage to and change limestone and other rocks. Lampenflora is especially dangerous to artifacts present in caves, such as cave paintings. The appearance of algae was one of the reasons the Lascaux cave was closed to the public. Plants can also upset cave ecology.
Reduction of lampenflora
There are several methods for reducing lampenflora. A lot of measures involve changing lighting in caves, such as lighting which only activates when people are nearby, led lighting which produces less heat, and placing lighting further away from surfaces. Reducing red and blue light in favor of yellow light can also help, but generally makes caves less visually appealing and can make certain structures less visible. Even with special lighting certain algae species can still appear.
Lampenflora can also be periodically removed either physically or chemically. The use of phytotoxic compounds must take into account the integrity of the ecology both inside and outside the cave, and the health of visitors and cave guides.
References
External links
Everything you need to know about LAMPENFLORA
The Green Slime that Flourishes in Light-Filled Caves
Down with lampenflora
Solutions to limit the influences of lamp-flora in tourist caves in Halong Bay
Plants and humans
Cave organisms
Artificial ecosystems
Lighting
Historic preservation | Lampenflora | [
"Biology"
] | 766 | [
"Artificial ecosystems",
"Plants and humans",
"Plants",
"Cave organisms",
"Organisms by habitat",
"Ecosystems",
"Humans and other species"
] |
67,070,255 | https://en.wikipedia.org/wiki/Dual-rotor%20motor | A dual-rotor motor is a motor having two rotors within the same motor housing. This rotor arrangement can increase power volume density, efficiency, and reduce cogging torque.
Stator on the outside
In one arrangement, the motor has an ordinary stator. A squirrel-cage rotor connected to the output shaft rotates within the stator at slightly less than the rotating field from the stator. Within the squirrel-cage rotor is a freely rotating permanent magnet rotor, which is locked in with rotating field from the stator. The effect of the inner rotor is to reenforce the field from the stator.
Because the stator slips behind the rotating magnetic field inducing a current in the rotor, this type of motor meets the definition of an induction motor.
Stator between rotors
In another arrangement, one rotor is inside the stator with a second rotor on the outside of the stator. The photo labelled FIG. 8 is from a patent application. It shows two rotors assembled into a single unit, with eight permanent magnets attached to the outer surface of the inner rotor, and eight to the inner surface of the outer rotor.
Vendors are working on both axial and radial flux configurations. In one axial flux design, the rotor is a disk that sits between two symmetric rotor disks.
References
Electric motors | Dual-rotor motor | [
"Technology",
"Engineering"
] | 265 | [
"Engines",
"Electric motors",
"Mechanical engineering",
"Electrical engineering",
"Mechanical engineering stubs"
] |
67,070,270 | https://en.wikipedia.org/wiki/Phoratoxin%20and%20viscotoxin | Phoratoxins are a group of peptide toxins that belong to the family of thionins, a subdivision of small plant toxins (5000 kD MW). Phoratoxins are proteins present in the leaves and branches of the Phoradendron, commonly known as the American variant of the mistletoe, a plant commonly used as decoration during the festive season. The berries of the mistletoe do not contain phoratoxins, making them less toxic compared to other parts of the plant. The toxicity of the mistletoe is dependent on the host tree, since mistletoe is known to be a semi-parasite. The host tree provides fixed inorganic nitrogen compounds necessary for the mistletoe to synthesize phoratoxins.
Viscotoxins are similar plant thionins produced from the leaves and stems of the European mistletoe (Viscum album). It also contains the unrelated toxic lectin, viscumin. This protein functions by the same mechanism as ricin on ribosomal rRNA which permanently inactivates protein synthesis and is responsible for the massively higher toxicity of V. album compared to the North American variety which does not appear to contain this class of toxins.
History
The history of phoratoxin is filled with myths, legends, and other magical stories. Mistletoe is a semi-parasitic plant occasionally using oak trees as their host. To historic peoples such as the Gauls and the Druids, oak trees were sacred. This led to beliefs that the mistletoe containing viscotoxin was a cure all drug for illnesses. These stories lived on for many years and were spread through the Americas by European settlers who came to the United States and mistook the American mistletoe (Phoradendron) for the more toxic European mistletoe (Viscum album). This made sure the mysterious past belonging to viscotoxin is shared by phoratoxin.
Structure and reactivity
The folding motif and overall topology of phoratoxins are identical to that of crambin. Phoratoxin proteins fold into two anti-parallel amphipathic helices that are perpendicular to a double stranded beta sheet and a C-terminal coil region. The general configuration of the protein resembles the shape of the Greek capital letter gamma. Phoratoxin contains three disulfide bridges. Phoratoxin expresses different features that are typical for membrane active proteins, it is compact, contains many basic amino acid residues and it contains one weakly polar flat face.
It is likely that phoratoxins have multiple aggregation states and can either exist as a monomer, a dimer, or a tetramer consisting of a dimer of dimers. The state of aggregation depends on the presence of inorganic phosphate or phospholipids. The aggregates are hydrophobic and hydrophilic dimers, joined by intermolecular interaction. Bridging of the hydrophilic dimer is only possible when inorganic phosphate ion is present, making inorganic phosphate ion presence necessary for lattice formation. This inorganic phosphate ion increases the toxin stability by neutralizing the positively charged basic amino acids of the monomers, creating possibilities for more Van Der Waals interactions.
Phoratoxin is an amphipathic molecule, a feature that is frequently found in membrane binding proteins. Phoratoxin has a positive membrane binding site that can bind negatively charged phospholipids. This phospholipid binding site is located in between the alpha helix and the beta sheet. The phosphate fits in a binding pocket near Lys-1, while the glycerol part as well as the two termini of the bound phospholipid move towards the random coil region (residue 36–44).
Available forms
There are six forms of phoratoxin known to exist. Five out of six forms are 46 amino acids long; only phoratoxin D is 41 amino acids long. The differences between these six forms are mainly centered in the random coil region of the protein (residue 36-44/41). In phoratoxin F, Phe-18 and Gly-19 are mutated into a leucine and an alanine. Phenylalanine and leucine are both hydrophobic, however phenylalanine is large, aromatic and strand-preferring, while leucine is medium in size and prefers to be in a helix. Glycine and alanine are both small amino acids, but glycine prefers turns while alanine prefers helices, and glycine is extremely flexible and intermediate while alanine is hydrophobic. Assuming phoratoxin folds in the exact same manner as crambin residues 7-19 are in an alpha helix. This mutation makes the helix of phoratoxin F more stable than helix in the other phoratoxin forms. A second difference in the various forms of phoratoxin is Val-25/Ile-25, in the second alpha-helix coding region. The fact that valine and isoleucine are both beta branched, the beta sheet is their secondary structure of preference. Since both of these amino acids are also hydrophobic this mutation is thought to have little interference with the folding and stability of the protein. The last differentiation in amino acid configuration is at Asn-45/Asp-45/Thr-45. This mutation is not in a region coding for a specific secondary protein structure. Asparagine and aspartic acid are both hydrophilic, while threonine has intermediate hydrophilicity. Asparagine and aspartic acid are both larger than threonine, and both asparagine and aspartic acid like to be in a turn while threonine prefers a beta strand. Aspartic acid and asparagine carry a formal charge. This charge however is negative for aspartic acid and positive for asparagine.
Synthesis
Phoratoxin has not been synthesized in a lab yet. It can, however, be extracted from the Phoradendron. Phoratoxin is located most in the leaves and berries of the plant. It can be isolated from the plant by means of chromatography or extracted with an acid, and thereafter purified with an amide.
Metabolism
There is not a lot of available information about the mechanism of action of phoratoxin. It is however known that phoratoxin has a high affinity for phospholipids, and therefore able to disrupt cell membranes. There is no metabolic activity as the protein already expresses its toxic trait, and stays intact the way it was synthesized in the Phoradendron.
Efficacy and side effects
Phoratoxin can have many different effects depending on the dose. Symptoms can vary from very mild to severe effects and even death. Mild symptoms are diarrhea, abdominal pain, nausea and blurred vision.
More severe symptoms are reflex bradycardia, which is a reduction in the blood pressure due to the decrease in cardiac output via an increase in heart rate, negative inotropic effects on the heart muscle, which weakens the force of muscle contractions, and In high doses, the narrowing of skin and skeletal muscle blood vessels.
However, the average, healthy adult can withstand some of the toxin of the plant without having any symptoms. It is more dangerous and can be lethal for small kids and animals.
Phoratoxin is hemolytic and causes cell leakage and cell lysis by interacting with the phospholipids. This is used in a study for cancer treatment. The phoratoxin lyses the cancer cells, killing them. It supposedly helps with the chemotherapy and radiation as well, but little research has been done on this subject. In some countries, this is also used for illegal abortions, where tea is brewed from the leaves of the mistletoe plant.
Toxicity
Phoratoxin is the toxin that is present in the American mistletoe (Phoradendron leucarpum). Most cases that have led to toxicity of phoratoxin are due to the accidental ingestion of mistletoe during the Christmas season and are related to accidental intake of berries by children. There is only limited data concerning accidental exposure to American Mistletoe.
One study shows the symptoms of 1,754 exposures to mistletoe. There were no cases of major symptoms and only a small percentage had moderate symptoms. A few cases were present where the people had minor effects (symptoms that were minimally bothersome to the patient). The majority of the people who were exposed to the mistletoe had no symptoms. In all of the cases that were investigated in the study, there were no fatalities or had an outcome associated without morbidity.
Another study shows out of 92 human cases exposed to American mistletoe, there were 14 symptomatic cases, from which 11 were related to the exposure of phoratoxin. The symptoms included six gastrointestinal upset cases, two mild drowsiness cases, one eye irritation case, one ataxia case (21 months) and one case of seizure (13 months). The amount of ingested mistletoe ranged from one berry or leaf to more than 20 berries or 5 leaves. American mistletoe has also been associated with nausea, vomiting, abdominal cramps and diarrhea, but the development of these symptoms is very rare. Even though there is limited data present, the American mistletoe is not as toxic as most people think. The majority of the patients did not receive any symptoms.
Effects in vivo
In studies it has turned out that phoratoxin can depolarize the membrane of frog skeletal muscle. Phoratoxin increases the resting membrane conductance, this conductance is sensitive to external calcium. This relationship will indicate an interaction between Ca2+ and the toxin molecule at the membrane level. The Ca2+ dependence of the depolarizing effect of the toxin suggests that the phoratoxin B can alter the structural integrity of the membrane phospholipid layer. This indicated that the phoratoxin behaves as a detergent on the membrane.
Medical applications
Phoratoxin is hemolytic and can therefore depolarize the cell membranes in cardiac and skeletal muscles. It appears to be cytotoxic to cancer cells, for this reason the mistletoe is increasingly used as a natural and holistic treatment for cancer. However, this is not completely new, in 1904 a letter to The Lancet from a British officer in the Indian Army Medical Corps was written that the mistletoe mixtures were used to “purge away black bile and mucous humours” and “drawing out gross humours from the depths of the body”.
Prevention and treatment
There is no antiserum available for phoratoxin ingestion yet. However, there are a few steps in treating phoratoxin poisoning. First, it is important to wipe the mouth to remove any remaining pieces. Activated carbon can be administered to prevent further toxins to be absorbed in the body. Also, fluids can be administered via a drips line, if necessary. In case of a high dose of phoratoxin ingestion, gastrointestinal decontamination is performed.
Prevention of phoratoxin poisoning can be done by avoiding eating wild berries or plants in the wild, washing hands during hiking or camping in the wild before eating, and with the use of artificial rather than real decorative plants during the Christmas season.
References
Plant toxins | Phoratoxin and viscotoxin | [
"Chemistry"
] | 2,384 | [
"Chemical ecology",
"Plant toxins"
] |
67,070,273 | https://en.wikipedia.org/wiki/E-Residency%20of%20Lithuania | e-Residency of Lithuania is a program launched by Lithuania on 1 January 2021. The program will allow non-Lithuanian citizens to access services provided by the Lithuanian government and other institutions, such as company formation, declaration of taxes and opening of bank accounts. It provides the e-residents with a smart card, similar to the Lithuanian identity card, which can be used for electronic identification and electronic signature.
The e-residency scheme is aimed towards location-independent entrepreneurs such as software engineers and it is modelled after the e-Residency of Estonia.
As of January 2025, there have been no updates to the program, and it remains impossible to launch or operate a business through the Lithuanian e-Residency.
Application
An application for e-residency can be made online by filling a form to the Migration Department of Lithuania (). The applicant must then physically present themself to the Migration Department for the identification and collection of the biometric data. The biometric data collection service is provided by the diplomatic missions or the external service providers, thus making it possible to complete the application abroad. The status of an e-resident is granted for 3 years. , the application fee is 90 Euros.
The application is subject to certain checks, concerning national security, prevention of money laundering, etc. It also includes checks in the Schengen Information System for alerts by the other EU members.
Legislation
The status of e-residence is established and regulated by the Law on the Legal Status of Foreigners 2004 with the amendments from 2019. The authority which implements the legislation is the Migration Department under the Ministry of the Interior. The legal framework for the electronic identification and signatures is established by the Law on Electronic Identification and Trust Services for Electronic Transactions.
Statistics
In January 2023, the head of the Migration Department reported that the e-residency status was granted to more than 300 people. Taiwanese Minister of Digital Affairs Audrey Tang became the first minister to obtain the e-residency in Lithuania.
See also
E-governance
E-government
Economy of Lithuania
Taxation in Lithuania
References
External links
Apply for e-residency
Lithuania
E-democracy
2021 establishments in Lithuania
Government of Lithuania | E-Residency of Lithuania | [
"Technology"
] | 425 | [
"E-democracy",
"Computing and society"
] |
67,072,520 | https://en.wikipedia.org/wiki/Anelasticity | Anelasticity is a property of materials that describes their behaviour when undergoing deformation. Its formal definition does not include the physical or atomistic mechanisms but still interprets the anelastic behaviour as a manifestation of internal relaxation processes. It is a behaviour differing (usually very slightly) from elastic behaviour.
Definition and elasticity
Considering first an ideal elastic material, Hooke's law defines the relation between stress and strain as:
The constant is called the modulus of elasticity (or just modulus) while its reciprocal is called the modulus of compliance (or just compliance).
There are three postulates that define the ideal elastic behaviour:
(1) the strain response to each level of applied stress (or vice versa) has a unique equilibrium value;
(2) the equilibrium response is achieved instantaneously;
(3) the response is linear.
These conditions may be lifted in various combinations to describe different types of behaviour, summarized in the following table:
Anelasticity is therefore by the existence of a part of time dependent reaction, in addition to the elastic one in the material considered. It is also usually a very small fraction of the total response and so, in this sense, the usual meaning of "anelasticity" as "without elasticity" is improper in a physical sense.
The formal definition of linearity is: "If a given stress history produces the strain , and if a stress gives rise to , then the stress will give rise to the strain ." The postulate of linearity is used because of its practical usefulness. The theory would become much more complicated otherwise, but in cases of materials under low stress this postulate can be considered true.
In general, the change of an external variable of a thermodynamic system causes a response from the system called thermal relaxation that leads it to a new equilibrium state. In the case of mechanical changes, the response is known as anelastic relaxation, and in the same formal way can be also described for example dielectric or magnetic relaxation. The internal values are coupled to stress and strain through kinetic processes such as diffusion. So that the external manifestation of the internal relaxation behaviours is the stress strain relation, which in this case is time dependant.
Static response functions
Experiments can be made where either the stress or strain is held constant for a certain time. These are called quasi-static, and in this case, anelastic materials exhibit creep, elastic aftereffect, and stress relaxation.
In these experiments a stress applied and held constant while the strain is observed as a function of time. This response function is called creep defined by and characterizes the properties of the solid. The initial value of is called the unrelaxed compliance, the equilibrium value is called relaxed compliance and their difference is called the relaxation of the compliance.
After a creep experiment has been run for a while, when stress is released the elastic spring-back is in general followed by a time dependent decay of the strain. This effect is called the elastic aftereffect or “creep recovery”. The ideal elastic solid returns to zero strain immediately, without any after-effect, while in the case of anelasticity total recovery takes time, and that is the aftereffect. The linear viscoelastic solid only recovers partially, because the viscous contribution to strain cannot be recovered.
In a stress relaxation experiment the stress σ is observed as a function of time while keeping a constant strain and defining a stress relaxation function similarly to the creep function, with unrelaxed and relaxed modulus MU and MR.
At equilibrium, , and at a short timescale, when the material behaves as if ideally elastic, also holds.
Dynamic response functions and loss angle
To get information about the behaviour of a material over short periods of time dynamic experiments are needed. In this kind of experiment a periodic stress (or strain) is imposed on the system, and the phase lag of the strain (or stress) is determined.
The stress can be written as a complex number where is the amplitude and the frequency of vibration. Then the strain is periodic with the same frequency where is the strain amplitude and is the angle by which the strain lags, called loss angle. For ideal elasticity . For the anelastic case is in general not zero, so the ratio is complex. This quantity is called the complex compliance . Thus,
where , the absolute value of , is called the absolute dynamic compliance, given by .
This way two real dynamic response functions are defined, and . Two other real response functions can also be introduced by writing the previous equation in another notation:
where the real part is called "storage compliance" and the imaginary part is called "loss compliance".
J1 and J2 being called "storage compliance" and "loss compliance" respectively is significant, because calculating the energy stored and the energy dissipated in a cycle of vibration gives following equations:
where is the energy dissipated in a full cycle per unit of volume while the maximum stored energy per unit volume is given by:
The ratio of the energy dissipated to the maximum stored energy is called the "specific damping capacity”. This ratio can be written as a function of the loss angle by .
This shows that the loss angle gives a measure of the fraction of energy lost per cycle due to anelastic behaviour, and so it is known as the internal friction of the material.
Resonant and wave propagation methods
The dynamic response functions can only be measured in an experiment at frequencies below any resonance of the system used. While theoretically easy to do, in practice the angle is difficult to measure when very small, for example in crystalline materials. Therefore, subresonant methods are not generally used. Instead, methods where the inertia of the system is considered are used. These can be divided into two categories:
methods employing resonant systems at a natural frequency (forced vibration or free decay)
wave propagation methods
Forced vibrations
The response of a system in a forced-vibration experiment with a periodic force has a maximum of the displacement at a certain frequency of the force. This is known as resonance, and the resonant frequency. The resonance equation is simplified in the case of . In this case the dependence of on frequency is plotted as a Lorentzian curve. If the two values and are the ones at which falls to half maximum value, then:
The loss angle that measures the internal friction can be obtained directly from the plot, since it is the width of the resonance peak at half-maximum. With this and the resonant frequency it is then possible to obtain the primary response functions. By changing the inertia of the sample the resonant frequency changes, and so can the response functions at different frequencies can be obtained.
Free vibrations
The more common way of obtaining the anelastic response is measuring the damping of the free vibrations of a sample. Solving the equation of motion for this case includes the constant called logarithmic decrement. Its value is constant and is . It represents the natural logarithm of the ratio of successive vibrations' amplitudes:
It is a convenient and direct way of measuring the damping, as it is directly related to the internal friction.
Wave propagation
Wave propagation methods utilize a wave traveling down the specimen in one direction at a time to avoid any interference effects. If the specimen is long enough and the damping high enough, this can be done by continuous wave propagation. More commonly, for crystalline materials with low damping, a pulse propagation method is used. This method employs a wave packet whose length is small compared to the specimen. The pulse is produced by a transducer at one end of the sample, and the velocity of the pulse is determined either by the time it takes to reach the end of the sample, or the time it takes to come back after a reflection at the end. The attenuation of the pulse is determined by the decrease in amplitude after successive reflections.
Boltzmann superposition principle
Each response function constitutes a complete representation of the anelastic properties of the solid. Therefore, any one of the response functions can be used to completely describe the anelastic behaviour of the solid, and every other response function can be derived from the chosen one.
The Boltzmann superposition principle states that every stress applied at a different time deforms the material as it if were the only one. This can be written generally for a series of stresses that are applied at successive times . In this situation, the total strain will be:
or in the integral form, is the stress is varied continuously:
The controlled variable can always be changed, expressing the stress as a function of time in a similar way:
These integral expressions are a generalization of Hooke's law in the case of anelasticity, and they show that material acts almost as they have a memory of their history of stress and strain. These two of equations imply that there is a relation between the J(t) and M(t). To obtain it the method of Laplace transforms can be used, or they can be related implicitly by:
In this way though they are correlated in a complicated manner and it is not easy to evaluate one of these functions knowing the other. Hover it is still possible in principle to derive the stress relaxation function from the creep function and vice versa thanks to the Boltzamann principle.
Mechanical models
It is possible to describe anelastic behaviour considering a set of parameters of the material. Since the definition of anelasticity includes linearity and a time dependant stress–strain relation, it can be described by using a differential equation with terms including stress, strain, and their derivatives.
To better visualize the anelastic behaviour appropriate mechanical models can be used. The simplest one contains three elements (two springs and a dashpot) since that is the least number of parameters necessary for a stress–strain equation describing a simple anelastic solid. This specific basic behaviour is of such importance that a material that exhibits it is called standard anelastic solid.
Differential stress–strain equations
Since from the definition of anelasticity linearity is required, all differential stress–strain equations of anelasticity must be of first degree. These equations can contain many different constants to the describe the specific solid. The most general one can be written as:
For the specific case of anelasticity, which requires the existence of an equilibrium relation, additional restrictions must be placed on this equation.
Each stress–strain equation can be accompanied by a mechanical model to help visualizing the behaviour of materials.
Mechanical models
In the case where only the constants and are not zero, the body is ideally elastic and is modelled by the Hookean spring.
To add internal friction to a model, the Newtonian dashpot is used, represented by a piston moving in an ideally viscous liquid. Its velocity is proportional to the applied force, therefore entirely dissipating work as heat.
These two mechanical elements can be combined in series or in parallel. In a series combination the stresses are equal, while the strains are additive. Similarly, for a parallel combination of the same elements the strains are equal and the stresses additive. Having said that, the two simplest models that combine more than one element are the following:
a spring and dashpot in parallel, called the Voigt (or Kelvin) model
a spring and dashpot in series, called the Maxwell model
The Voigt model, described by the equation , allows for no instantaneous deformation, therefore it is not a realistic representation of a crystalline solid.
The generalized stress–strain equation for the Maxwell model is , and since it displays steady viscous creep rather than recoverable creep is yet again not suited to describe an anelastic material.
Standard anelastic solid
Considering the Voigt model, what it lacks is the instantaneous elastic response, characteristic of crystals. To obtain this missing feature, a spring is attached in series with the Voigt model. This is called the Voigt unit. A spring in series with a Voigt unit shows all the characteristics of an anelastic material despite its simplicity. It is differential stress–strain equation it therefore interesting, and can be calculated to be:
The solid whose properties are defined by this equation is called the standard anelastic solid. The solution of this equation for the creep function is:
where is called the relaxation time at constant stress.
To describe the stress relaxation behaviour, one can also consider another three-parameter model more suited to the stress relaxation experiment, consisting of a Maxwell unit placed in parallel with a spring. Its differential stress–strain equation is the same as the other model considered, therefore the two models are equivalent. The Voigt-type is more convenient in the analysis of creep, while the Maxwell-type for the stress relaxation.
Dynamic properties of the standard anelastic solid
The dynamic response functions and , are:
These are often called the Debye equations since were first derived by P. Debye for the case of dielectric relaxation phenomena. The width of the peak at half maximum value for is given by
The equation for the internal friction may also be expressed as a Debye peak, in the case where as:
The relaxation strength can be obtained from the height of such a peak, while the relaxation time from the frequency at which the peak occurs.
Dynamic properties as functions of time
The dynamic properties plotted as function of are considered keeping constant while varying . However, taking a sample through a Debye peak by varying the frequency continuously is not possible with the more common resonance methods. It is however possible to plot the peak by varying while keeping constant.
The basis of why this is possible is that in many cases the relaxation rate is expressible by an Arrhenius equation:
where is the absolute temperature, is a frequency factor, is the activation energy, is the Boltzmann constant.
Therefore, where this equation applies, the quantity may be varied over a wide range simply by changing the temperature. It then becomes possible to treat the dynamic response functions as functions of temperature.
Discrete spectra
The next level of complexity in the description of an anelastic solid is a model containing n Voigt units in series with each other and with a spring. This corresponds to a differential stress–strain equation which contains all terms up to order n in both the stress and the strain. Similarly, a model containing n Maxwell units all in parallel with each other and with a spring is also equivalent to a differential stress–strain equation of the same form.
In order to have both elastic and anelastic behaviour, the differential stress–strain equation must be of the same order in the stress and strain and must start from terms of order zero.
A solid described by such function shows a “discrete spectrum” of relaxation processes, or simply a "discrete relaxation spectrum". Each "line" of the spectrum is characterized by a relaxation time , and a magnitude . The standard anelastic solid considered before is just a particular case of a one-line spectrum, that can be also called having a "single relaxation time".
Mechanical spectroscopy applications
A technique that measures internal friction and modulus of elasticity is called Mechanical Spectroscopy. It is extremely sensitive and can give information not attainable with other experimental methodologies.
Despite being historically uncommon, it has some great utility in solving practical problems regarding industrial production where knowledge and control of the microscopic structure of materials is becoming more and more important. Some of these applications are the following.
Measurement of quantity of C, N, O and H in solution in metals
Unlike other chemical methods of analysis, mechanical spectroscopy is the only technique that can determine the quantity of interstitial elements in a solid solution.
In body centered cubic structures, like iron's, interstitial atoms position themselves in octahedral sites. In an undeformed lattice all octahedral positions are the same, having the same probability of being occupied. Applying a certain tensile stress in one direction parallel to a side of the cube dilates the side while compressing other orthogonal ones. Because of this, the octahedral positions stop being equivalent, and the larger ones will be occupied instead of the smallest ones, making the interstitial atom jump from one to the other. Inverting the direction of the stress has obviously the opposite effect. By applying an alternating stress, the interstitial atom will keep jumping from one site to the other, in a reversible way, causing dissipation of energy and a producing a so-called Snoek peak. The more atoms take part in this process the more the Snoek peak will be intense. Knowing the energy dissipation of a single event and the height of the Snoek peak can make possible to determine the concentration of atoms involved in the process.
Structural stability in nanocrystalline materials
Grain boundaries in nanocrystalline materials form are significant enough to be responsible for some specific properties of these types of materials. Both their size and structure are important to determine the mechanical effects they have. High resolution microscopy show that material put under severe plastic deformation are characterized by significant distortions and dislocations over and near the grain boundaries.
Using mechanical spectroscopy techniques one can determine whether nanocrystalline metals under thermal treatments change their mechanical behaviour by changing their grain boundaries structure. One example is nanocrystalline aluminium.
Determination of critical points in martensitic transformations
Mechanical spectroscopy allows to determine the critical points martensite start and martensite finish in martensitic transformations for steel and other metals and alloys. They can be identified by anomalies in the trend of the modulus. Using steel AISI 304 as an example, an anomaly in the distribution of the elements in the alloy can cause a local increase in , especially in areas with less nickel, and when usually martensite formation can only be induced by plastic deformation, around 9% can get formed anyway during cooling.
Magnetoelastic effects in ferromagnetic materials
Ferromagnetic materials have specific anelastic effects that influence internal friction and dynamic modulus.
A non-magnetized ferromagnetic material forms Weiss domains, each one possessing a spontaneous and randomly directed magnetization. The boundary zones, called Bloch walls, are about one hundred atoms long, and here the orientation of one domain gradually changes into the one of the adjacent one. Applying an external magnetic field makes domains with the same orientations increase in size, until all Bloch walls are removed, and the material is magnetized.
Crystalline defects tend to anchor the domains, opposing their movement. So, materials can be divided into magnetically soft or hard based on how much the walls are strongly anchored.
In these kind of materials magnetic and elastic phenomena are correlated, like in the case of magnetostriction, that is the property of changing size when under a magnetic field, or the opposite case, changing magnetic properties when a mechanical stress is applied. These effects are dependent on the Weiss domains and their ability to re-orient.
When a magnetoelastic material is put under stress, the deformation is caused by the sum of the elastic and magnetoelastic ones. The presence of this last one changes the internal friction, by adding an additional dissipation mechanism.
References
A.S. Nowick, B.S. Berry, Anelastic Relaxation in Crystalline Solids, Academic Press, New York and London 1972
R. Montanari, E. Bonetti, Spettroscopia Meccanica, AIM (2010) ISBN 97-88-88529-87-81
C.M. Zener, Elasticity and anelasticity of metals, University of Chicago Press, Chicago, Illinois, 1948
M.S. Blanter, Igor S. Golovin, H. Neuhauser, Hans-Rainer Sinning, Internal Friction in Metallic Glasses, Springer Series in Materials Science, 2007
Elasticity (physics) | Anelasticity | [
"Physics",
"Materials_science"
] | 4,055 | [
"Deformation (mechanics)",
"Physical phenomena",
"Physical properties",
"Elasticity (physics)"
] |
67,073,055 | https://en.wikipedia.org/wiki/RW%20Aurigae | RW Aurigae is a young binary system in the constellation of Auriga about away, belonging to the Taurus-Auriga association of the
Taurus Molecular Cloud. RW Aurigae B was discovered in 1944.
System
The two stars of the RW Aurigae system are separated by , equivalent to at the distance of RW Aurigae. The primary is a pre-main sequence star with a mass of , while the secondary has a mass of . These are loosely bound, and their orbital trajectory is nearly parabolic, with an orbital period of 1000−1500 years as evidenced by the structure of the ejected dust jets. The star system's orbit is retrograde compared to the rotation direction of the disk orbiting the primary star. RW Aurigae A is also suspected to be a close binary since 1999.
Properties
Both members of the binary are medium-mass objects still contracting towards the main sequence and accreting mass, RW Aurigae A at the rate of 0.1/Myr, and RW Aurigae B at the rate of 0.005/Myr. Their ages are equal to 3 million years.
The binary is surrounded by a complex accretion structure, containing a circumbinary shell, spiral arms, bow shocks and protoplanetary disks. RW Aur A is producing complex bipolar jets extending as far as 46 thousand AU from the star. Its protoplanetary disk is inclined to the line of sight by 45-60 degrees. It is not known if planetary formation in the disk has been arrested by stellar encounter or accelerated, as a wide range of debris sizes, consistent with both a collision cascade and ongoing planetesimal formation were detected. However, new work published in the 2018 - 2022 time period has shown strong evidence for the stochastic destruction of a large asteroid (approx. Vesta sized) differentiated planetesimal's Fe (iron) core at the inner edge of RW Aur A's accretion disk and the funneling of this material into the protostar's atmosphere and outflow jets. This implies both the creation of large asteroid-like bodies in far-out, cooler regions of the accretion disk and their migration into its innermost regions where they undergo catastrophic high energy collisions.
Variability
In 1906, Vitold Tserasky discovered that BD+30 792 is a variable star. It was subsequently given the variable star designation RW Aurigae. RW Aurigae A varies in brightness. It is a T Tauri variable, and a prototype for the eponymous class of RW Aurigae variables, exhibiting irregular dips in its light curve due to the rapidly changing geometry of the protoplanetary disk, disturbed by the periastron passage of RW Aurigae B. A previous periastron passage happened about 400 years ago. The long-lasting brightness dips in 2010-2011 and 2014-2016 reduced the star's brightness to magnitude 12.5, before recovering to visual magnitude 10.5-11.0 by August 2016.
The companion star is itself a variable of UX Orionis type, exhibiting both chaotic variations of brightness and short (less than one day) brightness dips due to continuing accretion and the inhomogeneity of the protoplanetary disk.
See also
FU Tauri
References
Binary stars
T Tauri stars
Circumstellar disks
Auriga
240764
BD+30 792
023873
J05074953+3024050
Aurigae, RW | RW Aurigae | [
"Astronomy"
] | 749 | [
"Auriga",
"Constellations"
] |
67,074,309 | https://en.wikipedia.org/wiki/Commonly%20prescribed%20drugs | Commonly prescribed drugs are drugs that are frequently provided by doctors in a prescription to treat a certain disease. These drugs are often first-line treatment for the target diseases and are effective in tackling the symptoms. An example of the target disease is ischemic heart disease. Some examples of commonly prescribed drugs for this disease are beta-blockers, calcium-channel blockers and nitrates.
In accordance with the pharmacological effects, commonly prescribed drugs can be divided into different groups. Drugs in the same group exert nearly identical effects, and can be utilized for treating the prevailing disease and sometimes, preventing complications of the existing diseases.
The use of commonly prescribed drugs can be reflected from the number of prescriptions of the drugs. Countries have their own dataset in recording the trend of commonly prescribed drugs. For example, the United States uses the Medical Expenditure Panel Survey (MEPS) and England uses the English Prescribing Dataset to record the prescription data for showing which drugs are commonly prescribed.
Understanding commonly prescribed drugs allows healthcare professionals to react to symptoms quickly and new treatment strategies can be developed. However, the data for commonly prescribed drugs may be outdated due to the time lag between data collection and publication as well as errors in data collection process.
History
Commonly prescribed drugs are prescribed according to guidelines around the world. For instance, for ischemic heart disease, the American College of Cardiology/American Heart Association (ACC/AHA) guideline is used in the United States and the European Society of Cardiology (ESC) guideline is used in Europe. Western guidelines are more commonly used for reference during the development of local practice guidelines due to the large number of western guidelines stored in guideline databases. The data of prescriptions are collected through the government, such as Medical Expenditure Panel Survey (MEPS) in America and the Pharmaceutical Benefit Scheme (PBS) in Australia, providing information on the actual prescription volume of drugs.
The United States
The Medical Expenditure Panel Survey (MEPS) conducted by the Agency for Healthcare Research and Quality (AHRQ) via the United States government is used to collect prescription data and data for other healthcare services, including home healthcare, children's health and preventive care in America. The survey started in 1996 and was the predecessor of the National Medical Expenditure Survey (NMES) and the National Medical Care Utilization and Expenditure Survey (NMCUES), which were conducted in 1977 (NMES-1), 1980 (NMCUES), and 1987 (NMES-2). The survey is updated every year with the renewed data from the country. The prescription data is published in the Prescribed Medicines File of the MEPS. The collection of data involves two components: Household component and the Medical Provider component. The household component collects self-reported data of the prescribed medicines and the demographic information of the respondents. The Medical Provider component acts as a piece of follow-back information provided by the pharmacy including a computerized printout for all prescription filled for the patient.
The United Kingdom
The English Prescribing Dataset (EPD) from the NHS Business Services Authority (NHSBSA) provides prescription data in the United Kingdom. The dataset was created in 2014. EPD is a combination of the Detailed Prescribing Information (DPI) and the Practice Level Prescribing in England (PLP). Both DPI and PLP are previous datasets from NHSBSA and NHS Digital respectively and EPD aims to replace them both in the future, but no specific date of replacement is given. EPD collects data from England, Wales, Scotland, Guernsey, Alderney, Jersey and the Isle of Man. EPD provides the item, quantity, net ingredient cost, actual cost, average daily quantity (ADQ), practice name and address details of the prescription.
Australia
The Pharmaceutical Benefits Scheme (PBS) from the Australian Government Department of Health provides the prescription data of prescriptions under PBS. PBS started in 1948 and the under co-payment prescriptions were added into the dataset from 1 April 2012. It publishes the PBS expenditure and prescriptions report every year recording prescription data in the past 12 months. The examples of data it provides are the top 50 drugs by total prescription volume and the top 50 drugs by government cost.
Benefits and limitations
Benefits
Understanding commonly prescribed drugs for different diseases can allow healthcare professionals to be more confident and decisive when choosing the most suitable treatment for the patient. This can also help develop new treatment strategies by researchers for more effective treatments. By enriching the knowledge of commonly prescribed drugs, pharmacy students will be more familiar with their mechanism of action, first-line therapy indications and side effects.
Limitations
Limitations include time lag for the conducted survey. The Medical Expenditure Panel Survey (MEPS) shows data recorded two years before the publishing of the survey. The time lag may lead to a difference in representing the current prescribing practice with the recorded data in the survey. Questionnaires which are self-reported tend to create recall bias. Respondents are likely to underreport the number of prescription drugs they have as those drugs are usually for short-term use and intermittent use, such as analgesics and topical agents.
Examples of commonly prescribed drugs
Two diseases from the top 10 causes of death introduced by the World Health Organization (WHO) in 2019 are used as examples, namely ischemic heart disease (ranked 1st) from cardiovascular diseases and Chronic Obstructive Pulmonary Disease from respiratory diseases (ranked 3rd). Although stroke is ranked 2nd by WHO, drugs used are similar to ischemic heart disease. Moreover, surgical interventions are commonly required, so it will be out of the scope of this article and it will not be introduced.
Ischemic Heart Disease
Ischemic Heart Disease (IHD) or coronary heart disease is the lack of supply of blood to an area in the heart, often due to plaque formation (atherosclerosis), causing inadequacy of oxygen to heart muscle and eventually leading to myocardial infarction. This disease can be classified into acute and chronic coronary heart disease. This disease caused 8.9 million deaths in 2019 and was ranked 1st in the top 10 causes of death globally by the World Health Organization (WHO).
The treatment of Ischemic Heart Disease can be divided into two directions: risk factor control and symptomatic relief.
Commonly prescribed drugs for Ischemic Heart Disease
Chronic Obstructive Pulmonary Disease (COPD)
Chronic Obstructive Pulmonary Disease (COPD) is a disease that causes chronic respiratory problems by gradually blocking the respiratory tracts. The continuous exposure to toxic fumes produced by cigarettes, vehicle engines and other human activities leads to inflammation of the respiratory tract, causing the development of COPD. The problem will deteriorate over time if it is not well managed. It will eventually cause respiratory failure and death in the late stage. It is the third deadliest disease reported by WHO in 2019 and it accounted for 6% of total deaths.
There are two types of management plan in COPD, namely regular treatment and acute exacerbation. In acute exacerbation, new medications will be added to the existing prescription and they will be stopped once the exacerbation is managed.
Combination inhalers
In patients with COPD, multiple inhalers need to be used at a time. There are two major types of inhaler, namely dry-powder inhaler(DPI) and metered-dose inhaler(MDI), and many more subtypes with different techniques for using them. Adherence is also an issue with the use of multiple inhalers. Generally with different types of inhalers, the adherence will be lowered. Proper inhaler technique and adherence are two of the factors that affect the management of COPD. Other factors include smoking cessation and participation in physical activities, to name but a few. With inappropriately applied inhaler technique and low adherence, there will be ineffective management of COPD, thus increasing in the burden on the healthcare sector. As a result, inhalers combining multiple medications are invented to tackle the problem.
References
Drugs | Commonly prescribed drugs | [
"Chemistry"
] | 1,666 | [
"Pharmacology",
"Chemicals in medicine",
"Drugs",
"Products of chemical industry"
] |
67,074,462 | https://en.wikipedia.org/wiki/Epichlo%C3%AB%20sinensis | Epichloë sinensis is a hybrid asexual species in the fungal genus Epichloë.
A systemic and seed-transmissible grass symbiont first described in 2020, Epichloë sinensis is a natural allopolyploid of Epichloë sibirica and Epichloë typhina subsp. poae.
Epichloë sinensis is found in Asia, specifically Northwest China, where it has been identified in the grass species Festuca sinensis.
References
sinensis
Fungi described in 2020
Fungi of China
Fungus species | Epichloë sinensis | [
"Biology"
] | 111 | [
"Fungi",
"Fungus species"
] |
67,076,178 | https://en.wikipedia.org/wiki/Zalgo%20text | Zalgo text, also known as cursed text or glitch text, is digital text that has been modified with numerous combining characters, Unicode symbols used to add diacritics above or below letters, to appear frightening or glitchy.
Named for a 2004 Internet creepypasta story that ascribes it to the influence of an eldritch deity, Zalgo text has become a significant component of many Internet memes, particularly in the "surreal meme" culture. The formatting of Zalgo text also allows it to be used to halt or impair certain computer functions, whether intentionally or not.
History
Zalgo text was pioneered in 2004 by a Something Awful forum member who created image macros of glitched or distorted cartoon characters exclaiming "Zalgo!" The text in the images was often distorted, and the style of the distortion became popularised as "Zalgo text". The characters were often depicted bleeding from their eyes, and forum members interpreted Zalgo as an unimaginable, eldritch apocalyptic figure.
Usage
Zalgo text is generated by excessively adding various diacritical marks in the form of Unicode combining characters to the letters in a string of digital text. Historically, it has primarily been used in horror or creepypasta Internet memes. Its seemingly improperly rendered or glitched-out characters make it prevalent amongst memes intended to make the reader's device appear to be malfunctioning. Zalgo text has become popular in the world of "surreal memes", which are intended to come across as bizarre or absurd. A common signifier of surreal memes, Zalgo text ties in with an overall aesthetic sensibility of the strange and impossible that includes elements such as clip art and strange-looking recurring characters but refuses to represent real-world elements such as real people or brands.
Zalgo text has also been used or alluded to outside of Internet memes. A fan-made campaign logo for the Michael Bloomberg 2020 presidential campaign, originally mistaken for an official logo, was described as closely resembling Zalgo text. In 2020, a teenager and TikTok creator submitted the word "hamburger" in Zalgo text for his school yearbook caption; when the yearbook was printed, the text overlapped his photograph and that of the student below him.
In addition to legitimate uses, Zalgo text has been used maliciously to crash or overwhelm messaging apps. Some versions of the Apple Messages app are unable to properly handle Zalgo text, and will crash if they try to render a message that contains such text. This behavior has been used to perform denial-of-service attacks against iOS users. Similarly, Zalgo messages sent over Gmail have caused crashes.
Influence
Zalgo text has led to the creation of other Internet-based glitch art. Performance artist Laimonas Zakas was inspired by Zalgo text to create Glitchr, a Facebook page that intentionally modifies and glitches Facebook code.
Though the most influential aspect of the original Zalgo creepypasta is the modified text characters, other aspects of the story have been popular as well. Fans of the story have conceptualized Zalgo as "either an unseen supernatural force, a secret cabal, or perhaps even an evil demigod" and compared it to the Great Old Ones in the work of H. P. Lovecraft. Fan art depictions of Zalgo have included drawings and short films.
See also
Unicode characters
List of creepypastas
References
Internet memes introduced in 2004
Software bugs
Unicode
Creepypasta
Diacritics | Zalgo text | [
"Mathematics"
] | 749 | [
"Symbols",
"Diacritics"
] |
67,078,284 | https://en.wikipedia.org/wiki/Crepundia | Crepundia are groups of amulets, often strung onto chains in Classical antiquity. They are similar to charm bracelets and are archaeologically associated with children.
Etymology
The singular form of the word, crepundium, derives from the Latin word crepare "to rattle or make a noise". The word crepundia may be confused with crepitacula, which refers to a form of rattle. Ancient examples may be made from ceramic, wood, or bronze.
History and features
Similar amulet chains were used in the ancient world from at least the 4th Century BC. Crepundia are referred to in Act 4 of Rudens (dated to c.211 BC) in which the character Palaestra describes the contents of a trinket box owned since childhood: a miniature gold sword inscribed with her father's name; a miniature gold axe inscribed with her mother's name; a silver knife; a little pig; a gold bulla. Crepundia are variable objects, but Martin-Kilcher defined five main sorts of objects that feature in them: noise-producing objects; meaningful shapes; those with ‘exterior qualities’; remarkable objects and curiosities; materials valued for their special properties.
The noise-making components of crepundia may have been used to calm distressed infants or children, or used as a toy.
Examples
Two infant burials from Aquincum (dated to the 1st-2nd centuries AD) between them contained small amber, bone, and glass pendants depicting: a money bag, a dolphin, a phallus, a comb, a cicada, an axe, and a male deity.
A child's grave from the Ponte Galeria in Rome contained a string of amber and bone beads, a pierced tooth, a faience figure of Bes and an amber phallus.
A child burial from Chichester included an iron bell, a red-slipped carinated bowl with a graffito of a cross on the base, and a small pebble, together described as crepundia by the excavators.
See also
Lunula (amulet)
Magic in the Greco-Roman world
References
Amulets
Childhood in ancient Rome
Archaeological artefact types
Necklaces
Bracelets
Magic items | Crepundia | [
"Physics"
] | 462 | [
"Magic items",
"Physical objects",
"Matter"
] |
67,079,155 | https://en.wikipedia.org/wiki/Prescription%20drug%20addiction | Prescription drug addiction is the chronic, repeated use of a prescription drug in ways other than prescribed for, including using someone else’s prescription. A prescription drug is a pharmaceutical drug that may not be dispensed without a legal medical prescription. Drugs in this category are supervised due to their potential for misuse and substance use disorder. The classes of medications most commonly abused are opioids, central nervous system (CNS) depressants and central nervous stimulants. In particular, prescription opioid is most commonly abused in the form of prescription analgesics.
Prescription drug addiction was recognized as a significant public health and law enforcement problem worldwide in the past decade due to its medical and social consequences. Particularly, the United States declared a public health emergency regarding increased drug overdoses in 2017. Since then, multiple public health organizations have emphasized the importance of prevention, early diagnosis and treatments of prescription drug addiction to address this public health issue.
Causes and risk factors
There are multiple risk factors that can increase the chance of developing drug addiction, including patient factors, nature of drug and over-prescription.
Patient factors
Studies have indicated that adolescents and young adults were particularly vulnerable to prescription drug abuse. People with acute or chronic pain, anxiety disorders and ADHD were at increased risk for addiction comorbidity. History of illicit drug use and substance use disorder were consistently identified as risk factors for prescription drug abuse.
Misuse of opioid analgesics is frequently associated with mental health disorder, including depression, posttraumatic stress disorder, and anxiety disorders. Some risk factors for opioid and benzodiazepine sedatives or tranquilizers addiction are white race, female sex, panic symptoms, other psychiatric symptoms, alcohol and cigarette dependence and history of illicit drug use. Addiction to pharmaceutical stimulants have been predominantly among adolescents and young adults.
Drug characteristics
Patients who have been prescribed medications to treat a health condition or disorder are shown to be more vulnerable to prescription drug abuse and addiction, especially when the prescribed medicine falls into the same drug classes of common illicit drugs. For example, methylphenidate and amphetamines are in the same stimulant category as cocaine and methamphetamine, while hydrocodone and oxycodone are under the opioid category as heroin.
Key pharmacological factors associated with drug addiction include:
high frequency of drug use
high doses administered
rapid rate of onset of action
high drug potency
co-ingestion of psychoactive substances with similar (eg. sedatives and alcohol) or different pharmacological profiles (eg. stimulants and nicotine) can result in additional reinforcement of addiction.
Over-prescription and doctor shopping
Health practitioners can prescribe drugs in a number of ways that inadvertently and unintentionally contribute to prescription drug abuse.. They may inappropriately prescribe drugs due to influence by ill-informed, careless or deceptive patients or by succumbing to patient pressure..
The American Medical Association describes four mechanism by which a physician becomes involved in overprescribing in its four-”Ds” model:
’’’Dated’’’: the physician is outdated regarding knowledge of pharmacology and the differential diagnosis and management of diseases.
’’’Duped’’’: the physician may be vulnerable to a manipulative patient.
’’’Dishonest’’’: a dishonest physician may be motivated to write prescriptions for controlled substances under financial incentives.
’’’Disabled’’’: a physician with medical or psychiatric disability such that they have “loose” standards in prescribing controlled substances.
The above over-prescription practices can lead to the aggravation of prescription drug addiction.
A person may also gain access to prescription drugs via doctor shopping.. "Doctor shopping" describes a practice in which a person searches for multiple sources of drugs by visiting different health practitioners and presenting a different list of complaints to each practitioner; the patient will then obtain multiple prescriptions and fill them at different pharmacies.
Commonly abused drug categories
Opioid analgesics
Opioid painkillers exert CNS depressant effects by binding to opioid receptors. Its psychoactive properties potentially cause euphoria. Changes in the pain management including more liberal opioids prescription for chronic pain conditions, prescription of higher doses and the development of more potent opioid drugs play an important role contributing to the current epidemic of prescription opioid addiction. Examples of opioid drugs include morphine, codeine, oxycodone, hydrocodone, fentanyl, tramadol and methadone.
Stimulants
Stimulants are drugs that increase alertness and attention. This class of drugs have been frequently prescribed for patients with attention deficit hyperactivity disorder (ADHD) in many countries. In addition to taking higher doses of medication than prescribed, stimulant users may also combine prescribed stimulants with illicit drugs or alcohol in order to induce euphoria.
Examples of prescribed stimulants include amphetamine, dextroamphetamine, methamphetamine and methylphenidate.
Anxiolytic sedative-hypnotics
Sedatives have potent, dose-dependent CNS depressant effects. These drugs exert a calming effect and may also induce sleepiness. Sedative-hypnotic medications are commonly prescribed for anti-anxiety or sleeping aid purposes.
A major class of sedative-hypnotics causing addiction is benzodiazepines, which includes alprazolam, diazepam, clonazepam and lorazepam.
Consequences
Prescription drug addiction is usually associated with both medical and social consequences.
Medical consequences
Different drug classes have different side effects. Long-term medical conditions induced by opioid include infection, hyperalgesia, opioid-induced bowel syndrome, opioid-related leukoencephalopathy and opioid amnestic syndrome. Misuse of prescribed opioids medications is associated with increased morbidity and mortality.
Syndromes of overdose of stimulants may include tremor, confusion, hallucinations, anxiety and seizures.
Inappropriate use of prescribed benzodiazepines may induce nystagmus, stupor or coma, altered mental status (most commonly depression) and respiratory depression.
Social consequences
Addiction to prescription drugs also brings social impacts. Due to the CNS effect caused by misuse of medications, people are more likely to have poor judgement and thus engaging in risky behaviors. Polydrug addiction with illegal or recreational drugs is also common. It was found that adolescents with opioid addiction show higher rates of past-year criminal behaviors. The risk of motor vehicle accidents may increase if consciousness is greatly reduced. Addiction may also deteriorate academic or work performance and worsen relationships.
Diagnosis
Signs and symptoms
The signs and symptoms of opioids addiction include decreased body temperature and blood pressure, constipation, decreased sex drive, euphoria and others. Conversely, people with addiction to stimulants often have increased blood pressure, heart rate, body temperature, decreased sleep and appetite. Stimulants may cause anxiety and paranoia as well. Addiction of benzodiazepines is diagnosed based on the withdrawal syndrome occurred after termination of regular use.
Benzodiazepine withdrawal symptoms are similar to anxiety, including insomnia, excitability, restlessness, panic attacks and so on.
Screening and testing
Screening tools with high validity are available to assess patients’ risk for opioid misuse, which include rapid opioid dependence screen (RODS), Severity of Dependence Scale (SDS) and OWLS.
There is a standardized list of diagnostic criteria provided by the Diagnostic and Statistical Manual of Mental Disorders for patients with positive screening results. Additionally, urine drug testing can be an accurate method to measure specific biomarkers after metabolism.
Treatment
Pharmacotherapies
When a chronic prescription drug user suddenly ceases the use of an addictive drug, the person may experience unpleasant withdrawal symptoms depending on the drug type. A constant opioid user may experience withdrawal symptoms such as nausea and diarrhea. Detoxification is a procedure which treats addicts in withdrawal with low doses of a synthetic opiate drug which helps reduce the severity of their withdrawal symptoms. This type of pharmacotherapy with an opioid agonist or antagonist is adopted widely, together with adjunct psychotherapy to prevent relapse. Examples of medications include methadone, naltrexone and clonidine.
Currently, no FDA-approved medications are available for stimulants addiction. However, some agents including bupropion, naltrexone and mirtazapine have demonstrated positive effects in treating addiction to amphetamine-type stimulants. Acetylcholinesterase inhibitors have shown to be a potential treatment target.
Notably, benzodiazepines addiction often occurs as a result of polydrug abuse, most commonly with opioids. Medically supervised detoxification remains the first-line treatment for benzodiazepines addiction. The use of other medication to aid withdrawal has not been well-developed.
Behavioral therapies
Cognitive behavioral therapy and the Matrix model are treatment options for stimulant addicts that have been shown to be effective in preventing relapse, despite that patients addicted to opioid may not respond well to behavioral therapy.
Prevention
Patients, healthcare providers, the government, pharmaceutical companies and a variety of stakeholders can contribute to the prevention of prescription drug misuse and its subsequent addiction.
Regulations regarding drug prescription
In addition to existing controlled substance scheduling systems, mandatory prescriber registration, education and training, many governments launched various initiatives and regulations to minimize misuse of prescription drugs.
For example, many healthcare providers are legally required to participate in local prescription-drug monitoring programs (PDMPs) to record patient drug use.
Nationwide PDMPS are effective in reducing abuse and diversion of prescription medications, and promote safer prescribing practices for patients. PDMPs are effective against doctor shopping and incidents of over-prescription.
Furthermore, different regions established specialized agencies to oversee drug addiction and its related regulations. The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) and the French public interest group OFDT were established in 1993 to provide information concerning drug addiction and consequences. Similarly, the US government founded the National Institute on Drug Abuse (NIDA) directed toward reducing drug misuse and overdose in 1974. In 2016, the Centers for Disease Control and Prevention (CDC) published its CDC Guideline for Prescribing Opioids for Chronic Pain.
Screening for addiction
Addiction disorders affect 20 to 50 percent of hospitalized patients; therefore physicians must integrate basic screening questions into all histories and physical examinations. Some major evidence-based assessment tools include the Addictions Neuroclinical Assessment, the National Institute on Drug Use Screening Tool, the CRAFFT 2.0 questionnaire, and the Drug Abuse Screening Test (DAST-10).
There are many programs to assist addictive individuals in achieving abstinence. In countries like Brazil, the US and India, addictive patients may be referred to 12-step programs such as Alcoholic Anonymous, Narcotics Anonymous, and Pills Anonymous.
Optimize alternative treatments
Safer, non-controlled and non-addictive medications serve as an alternative to controlled substances. For example, abuse-deterrent formulations (ADF) are drug formulations that lower a drug’s addictiveness and/or prevent misuse by snorting or injection. ADFs have shown to decrease the illicit value of drugs and effectively eradicate substance addiction.
Non-pharmacologic treatments with self-management strategies are highly recommended, such as behavioral treatments, relaxation techniques, physical therapy and psychotherapy.
Ensuring drug compliance
Pharmacists improve drug compliance by counselling patients on medication instructions, along with educating patients about potential side effects related to medications. Nevertheless, healthcare practitioners are responsible for recognizing problematic patterns in prescription drug use. They may also use prescription-drug monitoring programs (PDMPs) to track drug prescription and dispensing patterns in patients.
Patient-wise, some organizations have suggested ways to use prescription drugs properly. For example, the NIDA guideline recommends patients to:
following the directions as explained on the label or by the pharmacist
being aware of potential interactions with other drugs as well as alcohol
never stopping or changing a dosing regimen without first discussing it with the doctor
never using another person’s prescription and never giving their prescription medications to others
storing prescription stimulants, sedatives, and opioids safely.
Additionally, the U.S. Food and Drug Administration (FDA) provides a guideline for proper disposal of unused or expired medications.
Epidemiology
Non-medical use of prescription opioids has been documented in many countries, most notably in West and North Africa, the Near and Middle East, and North America.
United States
In 2005, the US National Survey on Drug Use and Health (NSDUH) demonstrated that 6.4 million people aged 12 or older had used prescription drugs for non-medical reasons during the past month, including pain relievers, tranquillizers and stimulants.
From 2006 to 2016, the total weight of stimulants prescribed in the US nearly doubled; however, the trend of prescription stimulant misuse has been gradually declining since 2017.
In 2017, it was estimated that approximately 76 million adults in the US were prescribed with opioid drugs in the previous year, with 12 percent of them reporting prescription opioid misuse between 2016 and 2017. An estimate of more than 1 million Americans misused prescription stimulants, 2 million misused prescription analgesics, 1.5 million misused tranquillizers, and 271,000 misused sedatives for the first time within the past year.
United Kingdom
In the United Kingdom, deaths from Tramadol (a synthetic opioid painkiller) overdose have risen to 240 per annum as of 2014.
Europe
In Europe, methadone is the most widely prescribed opioid substitution medication, accounting for about 63 percent of substitution clients, followed by 35 percent of clients treated with buprenorphine-based medications. An average of 6 percent of students from the EU and Norway reported lifetime use of sedatives or tranquillizers without a doctor’s prescription. In 2019, there was an increasing trend of prescription opioid addiction among Europe. Both amphetamines and methamphetamines are stimulant drugs commonly used in Europe, though amphetamines were more frequently prescribed. Methamphetamine use has traditionally been limited to the Czech Republic and Slovakia, although there were signs of increase in other European countries.
Asia
In comparison to the West, Asia-Pacific has a scarcity of data on prescription drug abuse. Still, the United Nations Office on Drugs and Crime stated that prescription drug abuse is a growing epidemic among recreational drug users in South Asia. Although relevant studies in China were limited, they revealed a similar prevalence of prescription drug misuse among adolescents and young adults, which was 5.9 percent and 25.9 percent, respectively. Most Asian studies, including those from Japan, Thailand, and Singapore, revealed the existence of prescription drug misuse in Asia, but their prevalence rates were found to be lower than that reported in Western developed countries. In 2019, there was an increasing trend of prescription opioid addiction in India.
South Africa
In comparison to the US, the prevalence of illicit drug use (including prescription drugs) in South Africa is relatively low. Prescription drug and over-the-counter (OTC) drug abuse together constitutes 2.6 percent of all primary illicit substances admitted to South African drug treatment facilities. However, lifetime illicit drug use for prescription or OTC medicines was highest among adolescents, at 16 percent prevalence rate, followed by inhalants, club drugs and others.
See also
Prescription drug
Drug addiction
Drug overdose
Controlled Substances Act
Harm reduction
Polysubstance abuse
Responsible drug use
Drug policy
Pharmacy (shop)
Regulation of therapeutic goods
External links
National Institute on Drug Abuse
The European Monitoring Centre for Drugs and Drug Addiction
References
Addiction
Addiction medicine
Psychoactive drugs | Prescription drug addiction | [
"Chemistry"
] | 3,345 | [
"Psychoactive drugs",
"Neurochemistry"
] |
59,138,954 | https://en.wikipedia.org/wiki/Myxotrichum%20chartarum | Myxotrichum chartarum is a psychrophilic and cellulolytic fungus first discovered in Germany by Gustav Kunze in 1823. Its classification has changed many times over its history to better reflect the information available at the time. Currently, M. chartarum is known to be an ascomycete surrounded by a gymnothecium composed of ornate spines and releases asexual ascospores. The presence of cellulolytic processes are common in fungi within the family Myxotrichaceae. M. chartarum is one of many Myxotrichum species known to degrade paper and paper products. Evidence of M. chartarum "red spot" mold formation, especially on old books, can be found globally. As a result, this fungal species and other cellulolytic molds are endangering old works of art and books. Currently, there is no evidence that suggests that species within the family Myxotrichaceae are pathogenic.
History and taxonomy
Myxotrichum chartarum was discovered by Gustav Kunze in 1823, along with another species in the new genus Myxotrichum, Myxotrichum murorum.
There has been much confusion within the genus Myxotrichum due to numerous revisions in classification over the years and the scarcity of isolations. Eventually, the genus, Myxotrichum became associated with ascomycota fungi which are dematiaceous hyphomycetes, commonly known as black yeasts or moulds. At the microscopic level, these fungi have a mesh-like surrounding structures, peridium, with hooked appendages.
It was mistakenly placed in the genus Oncidium by Nees, also in 1823, though that name which was already in use for a genus of orchid, giving Myxotrichum priority. In 1838, August Carl Joseph Corda classified M. chartarum as a hyphomycete in the family Sporotrichacheae, as species belonging to this family had ornate appendages resembling deer antlers. In 1854, Corda separated M. chartarum from Myxotrichum into the newly established genus, Actinospira because he believed it to produce conidia rather than ascospores. In 1959, Kuehn, among other investigators, reviewed the status of the family Gymnoascaceae and placed M. chartarum into the ascomycetous genus, Myxotrichum rather than the newly established genus for conidial forms, Myxotrichella.
In 1875, Fuckel declared M. chartarum to be the conidial form of Chaetomium kunzeanum. Fries thought M. chartarum was a conidial form of Chaetomium chartarum. His opinion was supported by Boulanger in 1897. Their revelation was founded because of the high resemblance between Chaetomium and Myxotrichum fungal families due to the presence of ornamental hairs. In 1889, Richon thought M. chartarum was the conidial form of Cephalotheca sulfurea, disputing the claim of Fuckel. In 1891, Constantin showed that M. chartarum belonged to the newly established family, ascomycete of the family Gymnoascaceae, for ascomycetes that lacked true cleistothecia or perithecia. In 1892, Rabenhorst classified M. chartarum into the order Gymnoascaceae. This was later supported by Schroter in 1893. Fischer later recognized the existence of ascospores in M. chartarum, but a distinct lack of conidial structures. In 1893, Schroeter reviewed family Gymnoascaceae and placed species with uncinate appendages within the genus, Myxotrichum without regard for other characteristics.
Different forms of M. chartarum were isolated by Robak and Udagawa that resembled a phenotypically similar species. The isolate discovered by Robak (1932) of M. carminoparum resembled M. chartarum in every way except in the characteristically flattened apical area. Another isolate was discovered by Udagawa (1963) to have flattened appendages, but the size of the ascomata was smaller, resembling those from M. carminoparum. Later, the species, M. chartarum and M. carminoparum were merged due to the high resemblance between the two species.
Growth and morphology
Growth in its natural environment
The ascospores can also be described as being yellow to orange in colour with a rounded football shape having longitudinal striations and a diameter between 6-8 μm on the long side and 5-8 μm on the short side.
Asci appear hyaline, globular, and contain the typical quantity of 8 ascospores each, the size of which are 3-5 μm on the long side and 2-3 μm on the short side. When the spores mature, they are released en masse, producing a cloud of brown-coloured dust.
Ascocarps appear dark and spherical with short appendages, and when filled with its yellow to orange spores, the ascocarp can appear green or copper. The diameter of the ascocarp is 150-555 μm. The spore mass fills the ascocarps between one-third and three-fourths of the total volume at peak maturity. The surrounding Gymnothecium has septate appendages that are straight and elongated. Branching points present as uncinate, or curved spines that are wider or flattened at the apices.
Commonly found in Myxotrichum species are the secondary and tertiary branching of peridial hyphae. These branches can be identified by the lighter colouring in comparison to the ascocarp of the fungi, or truncation that results from the fragility of such branching. These truncations were previously thought to have been the release of conidiophores, but no evidence was found on initial conidiophore attachment.
Life cycle
There are few records of the asexual or anamorphic stage within the family Gymnascaceae. Descriptions made by Kuehn (1955) and Robak (1932) described oidia and chlamydospores, though rare in occurrence. However, Benjamin (1956) acknowledged that there were indeed arthrospores and aleuriospores present in Gymnascaceae. The anamorphs of M. chartarum may belong to the genera, Malbranchea and Oidiodendron.
Growth in laboratory culture
In culture and grown at 25 °C, M. chartarum appears yellow and fluffy. Some cultures had areas that were black in appearance, which were due to visible mature ascomata. However, growth was restricted at this temperature, as fungi in the family Myxotrichaceae have a preference for temperatures below 18 °C. At temperatures of 18 °C, the fungus grew at 2 cm a month. Optimal growing temperatures were described as being between +5 and +7 °C.
Production of a red-brown pigment when grown on mycelia and on certain culture media, functions to detoxify the surrounding environment. This is due to a reaction produced by the laccases secreted in the presence of polyphenols. The presence of pigmentation occurs early on for polyphenol detection. However, this effect weakens when the fungus is exposed to higher levels of polyphenols, indicating metabolic function inhibition caused by the presence of these compounds.
Habitat and ecology
M. chartarum is known for its inhabitation of paper and paper products. The specific epithet, chartarum, originated from the Latin word for paper and is in reference to its initial discovery from paper in books, and its ability to decay these materials through the production of cellulose-degrading enzymes (cellulases). It was deemed a “material pathogen”, since it is able to degrade specific materials for a source of nutrition. It has also been recorded to inhabit other materials such as, drywall, straw, decaying leather, cloth, grouse dung, rabbit dung, bat guano, soil, leaves and fruit. Reports of M. chartarum have come from around the world. Known distribution areas are as follows: Germany, Russia, Italy, France, Switzerland, England, Japan, Austria-Hungary, Czechoslovakia, Maine, Massachusetts, Ontario, New York. The endemic region of this fungus is currently unknown. The presence of curved spines allow the fungus to adhere to the fur of animals, allowing the fungus to disperse to other areas.
It has been observed by multiple researchers that M. chartarum exhibited slow growth between temperatures of 5-7 °C, so this fungus is classified as a psychrophilic organism. However, no growth was observed at 37 °C and since it is unable to grow at the human body temperature, this fungus is not a disease agent or an opportunistic pathogen.
As found by Tribe and Weber (2002), optimal growth in culture can be achieved on mineral salt agar with a sheet of Cellophane as the only carbon source. In basements or cellars, M. chartarum has a preference for gypsum board ceilings and building paper on concrete surfaces on the cold side of foundation walls. For optimal growth, it requires a relative humidity of greater than 98%. Salinity and pH preferences are unknown, but it is thought to be halo-tolerant.
References
External links
Photos of Myxotrichum chartarum on Global Biodiversity Information Facility
Onygenales
Fungi described in 1823
Fungus species | Myxotrichum chartarum | [
"Biology"
] | 2,011 | [
"Fungi",
"Fungus species"
] |
59,138,960 | https://en.wikipedia.org/wiki/Marriage%20leave | Marriage leave is the legal right to enjoy leave of absence by an employee due to them getting married without loss of wages.
Status around the world
In the Republic of Ireland, civil servants are entitled 5 days.
In Malta, every employee is entitled to 2 days' marriage leave.
In Spain, an employee is entitled to 15 calendar days from the day of the wedding.
In Vietnam, according to the Labor Code, an employee is entitled to 3 days of paid leave when they get married, and 1 day of paid leave when a child of theirs get married. They are also entitled to 1 day of unpaid leave when their father, mother, natural brother or sister gets married.
See also
Honeymoon
References
Marriage
Intimate relationships
Labor
Holidays
Social programs
Demography
Family
Family law
Marriage law | Marriage leave | [
"Environmental_science"
] | 154 | [
"Demography",
"Environmental social science"
] |
59,138,999 | https://en.wikipedia.org/wiki/LARCO | The General Mining and Metallurgical Company SA (), better known as LARCO (ΛΑΡΚΟ), is a ferro-nickel production company in Greece. It has mines in the region of Euboea, Neo Kokkino, Kastoria and Servia. The company also has a metallurgical plant in Larymna, which employs the majority of the company's employees.
LARCO was founded in 1963 by Prodromos Bodosakis-Athanasiadis, with headquarters in Marousi in Athens. In 1966, the construction of the factory in Larymna was completed and in 1968 the construction of a settlement for the workers and their families was completed. The mines of Euboea were fully exploited in 1969 and in 1972 two new electric furnaces were added. In 1977, Europe's first long-distance conveyor belt, with a length of 7.5 km, was installed to reduce the cost of transporting the ore by truck. The ore exploited by the company is the Nickel limonite. The deposits exploited by the company undergo surface mining (open pit method) while only 2% are mined underground. The final result is a granular, high purity, low carbon carbon ferric, which is used exclusively in the production of stainless steel and is transported from the port of Larymna.
References
External links
Manufacturing companies established in 1963
Manufacturing companies based in Athens
Greek brands
Steel companies of Greece
Greek companies established in 1963 | LARCO | [
"Chemistry"
] | 306 | [
"Metallurgical industry of Greece",
"Metallurgical industry by country"
] |
59,139,060 | https://en.wikipedia.org/wiki/List%20of%20Union%20Pacific%20Railroad%20civil%20engineers%201863%20to%201869 | This is a partial list of Union Pacific railroad civil engineers who worked on the Union Pacific railway in its initial construction from Council Bluffs, Iowa to Promontory Summit, Utah from its groundbreaking on December 1, 1863, to its completion on May 10, 1869.
List
Ainsworth, Danforth Hulburt, (1828-1904) 1865-1866. (Engineer in charge of surveys, 1865; Div. Engineer)
Appleton, Francis Everett (1842-1877)
Armstrong,H.N. 1868-1869 (Division engineer - Cheyenne to Wasatch)
Bates, Cpt Thomas H. (1833-1927) (Division Engineer - Salt Lake City, Utah)
Bissell, Hezekiah (1835-1928) (Civil Engineer - UPRR, 1864-1869) Bissell was involved in the construction of the Dale Creek crossing and reportedly made the decision to use rope and chain to anchor the bridge from high winds.
Blickensderfer, Jacob (1816-1899)
Brown, Percy T. (d1867) and L. L. Hills (d1867)
In July 1867, Mr. Percy T. Brown, (assistant engineer) whose division extended from the North Platte to Green River, was running a line across the Laramie Plains. His party was camped on Rock Creek where they were attacked by the Sioux. Brown was out on the line with most of the party, but those in the camp were able to hold the Indians off, but a small party out after wood, under a promising young fellow named Clark, a nephew of Thurlow Weed, of New York, was killed with one of his escorts, and several of the escorts were wounded. Brown, in reconnoitering the country, ... struck 300 Sioux Indians who were on the warpath. He had with him eight men of his escort. Brown died in the fight.
Case, Francis M. (1835-1912) 1865-1867. (Division Engineer - UPRR)
Casement, John S. (1829-1909) (Casement Brothers construction, 1866-1869)
Dey, Peter A. (1825-1911) (Locating engineer; engineer in charge of preliminary survey-UPRR, 1863-1864.)
Dixon, Wiley B. 1864 (Engineering corp.)
Dillon, Sidney (1812-1892)
Dodge, Grenville Mellen (1831-1916) (Chief engineer - UPRR, 1866-1870; director, 1869-1973; U.S. representative - Iowa, 1867-1869)
Eddy, J. M., served with Dodge during the Civil War and part of the 1867 expedition wherein Dodge laid out the line to Cheyenne.
Edwards, Ogden 1864-1865. (Division engineer - UPRR)
Eicholtz, Col. Leonard H. (1827-1911) 1868. (Bridge Engineer - UPRR)
Evans, James A. (1827-1887) 1864-1869 (Division engineer - UPRR)
Ferguson, Arthur Northcote (1842-1906) 1865-1869. (Second assistant engineer- UPRR Eastern Division)
Golay, Philip, civil engineer (1827-1898). Golay worked on the UPRR Eastern Division.
Gray, E.F. 1869. Civil engineer
Harding, Henry, Civil engineer 1865-1870) (1837-1910), a Union Pacific Railroad engineer from Hartland, VT. Harding was one of the landowners shown on the map at a plot just west of Cheyenne. He entered into Norwich University in Vermont, in 1852, where he met Grenville Dodge. Harding worked on eastern railroads until 1865 when Dodge hired him to work as an assistant engineer on the Union Pacific. Harding's specific responsibility was the architectural backbone of the road; he designed bridges, station houses, roundhouses, etc. He would go on to work for the United States Engineering Corps, 1873-1890. He retired in 1890 to his hometown of Hartland.
Hayden, Ferdinand Vandiveer, 1868-1869. (Geologist, author - "Geology of UPRR Route")
Henry, John E. (Director - UPRR, 1863-1866; general superintendent and chief engineer - UPRR Eastern Division, 1864; general superintendent - N.E. road, 1864; chairman - committee on construction):
Hodge, James Thatcher, (1816-1871) -1863. (Geologist) succeeded by David Van Lennep (1826-1910)
Hodges, Fred S. (1865-1869 Engineering corp - rodman; assistant engineer):
House, J. E. 1864-1868. Future Chief Engineer of the UPRR, laid out townsites in Utah.
Hoxie, Herbert Melville (1830-1886)
Hudnutt, Col. Joseph Opdyke (1824-1910) 1869 (Division Engineer)
Hurd, Major Marshall Farnam (1823-1903) Dodge's staff engineer during the Civil War, who became unit chief in what Dodge called some of the most difficult Indian Territory. Mount Hurd is named after him.
Kelly, J.H., 1865. (Engineering corp - chairman)
Ledlie, James H. (1832 – 1882) bridge engineer
Maxwell, James Riddle (1836-1912)
McCabe, J. F.
Morris, Thomas Burnside (1842-1885) 1869. (Construction engineer)
North, Edward P. (1836-1911) Chicago, 1868-1869. (Resident Engineer)
O'Neill, John
Rawlins, John Aaron (1831–1869)
Reed, Samuel B. (1818-1891) (Locating engineer - UPRR, 1864-1865; engineer of construction; superintendent of operations, 1866-1869)
Rosewater, Andrew (b1848)
Seymour, Col. Silas (1817-1890)
Sharman, Charles H. (1841-1938) Sharman's journal of his working on the project provided the source material for Western fiction author Ernest Haycox to write a story called the "troubleshooter" in Collier's magazine in 1936. Thus, Sharman's manuscript written by a civil engineer became the basis for the movie, "Union Pacific", released in 1939.
Sickels, Theophilus E., 1870. (Chief engineer and superintendent - UPRR, 1870)
Williams, Jesse Lynch, 1864-1868. (Civil engineer; government director, 1864-1869)
See also
First transcontinental railroad
List of people associated with rail transport
List of civil engineers
List of US military railroad civil engineers in the American Civil War
Notes
External links
Engineers of U.P.R.R. at the Laying of the Last Rail, Promontory 1869 Work (by Andrew J. Russell), identified by Oakland Museum of California.
Nebraska State Historical Society Manuscript Finding Aid for Record Group 3761.AM: Union Pacific Railroad (Omaha, Neb.)
Building the Union Pacific-From Wyoming Tales and Trails
References
Sources
Athearn, R. G. (1971). Union Pacific country. Lincoln: University of Nebraska Press.
Dodge, Grenville Mellen. How We Built the Union Pacific Railway: And Other Railway Papers and Addresses. Vol. 447. US Government Printing Office, 1910. List of civil engineers on page 37 of 1910 material.
Galloway, John Debo. The First Transcontinental Railroad: Central Pacific, Union Pacific. Simmons-Boardman, 1950. Accessed at
Heier, Jan Richard. "Building the Union Pacific Railroad: A study of mid-nineteenth-century railroad construction accounting and reporting practices." Accounting, Business & Financial History 19.3 (2009): 327-351. Accessed at
Klein, Maury. Union Pacific: 1862-1893. Vol. 1. U of Minnesota Press, 2006.
Manuscript Collections
Casement Collection, 1795-1959. c. 2,000 items. Incl. a large group of letters written by John S. Casement about the Union Pacific. Kansas State U. Lib. and Dept. of Hist., Manhattan. 60-1211
Casement, John S. 158 items. Incl. correspondence, relating to the Union Pacific, 1866-69. Huntington Lib., San Marino.
Papers of Levi O. Leonard, Collection Dates: 1850–1942, Special Collections Department, the University of Iowa Libraries, Accessed at
First transcontinental railroad
History of rail transportation in the United States
Railway lines in the United States
Union Pacific Railroad
American frontier
History of United States expansionism
Railway lines in Omaha, Nebraska
Rail transportation in Utah
1860s in the United States
Historic Civil Engineering Landmarks
19th-century American engineers
Union Pacific civil engineers (1863-1869) | List of Union Pacific Railroad civil engineers 1863 to 1869 | [
"Engineering"
] | 1,751 | [
"Civil engineering",
"Historic Civil Engineering Landmarks"
] |
59,141,049 | https://en.wikipedia.org/wiki/Polynomial-time%20counting%20reduction | In the computational complexity theory of counting problems, a polynomial-time counting reduction is a type of reduction (a transformation from one problem to another) used to define the notion of completeness for the complexity class ♯P. These reductions may also be called polynomial many-one counting reductions or weakly parsimonious reductions; they are analogous to many-one reductions for decision problems and they generalize the parsimonious reductions.
Definition
A polynomial-time counting reduction is usually used to transform instances of a known-hard problem into instances of another problem that is to be proven hard. It consists of two functions and , both of which must be computable in polynomial time. The function transforms inputs for into inputs for , and the function transforms outputs for into outputs for .
These two functions must preserve the correctness of the output. That is, suppose that one transforms an input for problem to an input for problem , and then one solves to produce an output . It must be the case that the transformed output is the correct output for the original input . That is, if the input-output relations of and are expressed as functions, then their function composition must obey the identity . Alternatively, expressed in terms of algorithms, one possible algorithm for solving would be to apply to transform the problem into an instance of , solve that instance, and then apply to transform the output of into the correct answer for .
Relation to other kinds of reduction
As a special case, a parsimonious reduction is a polynomial-time transformation on the inputs to problems that preserves the exact values of the outputs. Such a reduction can be viewed as a polynomial-time counting reduction, by using the identity function as the function .
Applications in complexity theory
A functional problem (specified by its inputs and desired outputs) belongs to the complexity class ♯P if there exists a non-deterministic Turing machine that runs in polynomial time, for which the output to the problem is the number of accepting paths of the Turing machine. Intuitively, such problems count the number of solutions to problems in the complexity class NP. A functional problem is said to be ♯P-hard if there exists a polynomial-time counting reduction from every problem in ♯P to . If, in addition, itself belongs to ♯P, then is said to be ♯P-complete. (Sometimes, as in Valiant's original paper proving the completeness of the permanent of 0–1 matrices, a weaker notion of reduction, Turing reduction, is instead used for defining ♯P-completeness.)
The usual method of proving a problem in ♯P to be ♯P-complete is to start with a single known ♯P-complete problem and find a polynomial-time counting reduction from to . If this reduction exists, then there exists a reduction from any other problem in ♯P to , obtained by composing a reduction from the other problem to with the reduction from to .
References
Reduction (complexity) | Polynomial-time counting reduction | [
"Mathematics"
] | 591 | [
"Reduction (complexity)",
"Functions and mappings",
"Mathematical relations",
"Mathematical objects"
] |
59,141,451 | https://en.wikipedia.org/wiki/Asimina%20Arvanitaki | Asimina Arvanitaki (born 1980) is a Greek theoretical physicist and Stavros Niarchos Foundation Aristarchus Chair in Theoretical Physics at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada. In 2017, she was awarded the New Horizons in Physics prize.
Areas of research
Arvanitaki's work has focused on finding novel experiments to explore topics in theoretical physics. Her work has been described as working at the "precision frontier" as it involves measuring very small variations in well-understood phenomena to illuminate theoretical predictions.
In 2016, Arvanitaki, Savas Dimopoulos and Ken Van Tilburg proposed a method of detecting dark matter as a matter wave, using conventional gravitational wave detectors. She has proposed using the Advanced Laser Interferometer Gravitational-Wave Observatory to observe the gravitational waves from black hole collisions to detect the presence of QCD axions, a candidate for explaining dark matter. She has also proposed using neutrino and gamma-ray telescopes, such as the Fermi telescope, Hess, or IceCube, to search for dark matter decay products predicted by certain theories of super-symmetry.
Education and early career
Arvanitaki pursued her post-doctoral research at Stanford University. She joined the Perimeter Institute in 2014. She is the first woman to hold a named chair at the institute. Arvanitaki suggested naming the chair for Aristarchus — the ancient Greek astronomer who surmised that the Earth rotated around the sun centuries before Coperniucs — in a nod to the cosmological scope of her research, the Greek background of the Stavros Niarchos Foundation, and her own Greek origin.
References
1980 births
Living people
Theoretical physicists
21st-century Greek physicists
21st-century Canadian physicists
21st-century women physicists | Asimina Arvanitaki | [
"Physics"
] | 370 | [
"Theoretical physics",
"Theoretical physicists"
] |
59,141,724 | https://en.wikipedia.org/wiki/NGC%20703 | NGC 703 is a lenticular galaxy located 240 million light-years away in the constellation Andromeda. The galaxy was discovered by astronomer William Herschel on September 21, 1786 and is also a member of Abell 262.
NGC 703 is classified as a radio galaxy.
See also
List of NGC objects (1–1000)
References
External links
703
6957
Andromeda (constellation)
Astronomical objects discovered in 1786
Lenticular galaxies
Abell 262
1346
Radio galaxies | NGC 703 | [
"Astronomy"
] | 97 | [
"Andromeda (constellation)",
"Constellations"
] |
59,142,155 | https://en.wikipedia.org/wiki/NGC%20704 | NGC 704 is a lenticular galaxy located 220 million light-years away in the constellation Andromeda. The galaxy was discovered by astronomer William Herschel on September 21, 1786 and is also a member of Abell 262.
See also
List of NGC objects (1–1000)
References
External links
704
006953
Andromeda (constellation)
Astronomical objects discovered in 1786
Lenticular galaxies
Abell 262
01343 | NGC 704 | [
"Astronomy"
] | 88 | [
"Andromeda (constellation)",
"Constellations"
] |
59,142,827 | https://en.wikipedia.org/wiki/NGC%20705 | NGC 705 is a lenticular galaxy located 240 million light-years away in the constellation Andromeda. The galaxy was discovered by astronomer William Herschel on September 21, 1786 and is also a member of Abell 262.
Although NGC 705 is an early type galaxy, it has a dust lane that is concentrated toward its central region. It is projected to lie about from the cd-galaxy NGC 708.
See also
List of NGC objects (1–1000)
References
External links
705
6958
Andromeda (constellation)
Astronomical objects discovered in 1786
Lenticular galaxies
Abell 262
1345 | NGC 705 | [
"Astronomy"
] | 123 | [
"Andromeda (constellation)",
"Constellations"
] |
59,143,410 | https://en.wikipedia.org/wiki/Uncinocarpus%20uncinatus | Uncinocarpus uncinatus is a species of microfungi that grows on dung and other keratinous materials such as bone. It was the second species to be designated as part of the genus Uncinocarpus. The species was first described by Randolph S. Currah in 1985; synonyms include Myxotrichum uncinatum and Gymnoascus uncinatus.
Morphology
In culture, colonies of U. uncinatus are yellow to orange-brown to red-brown in colour, growing paler towards the margin. Like other members of Uncinocarpus, it develops hooked and occasionally spiralling (uncinate) appendages which typically, but not always, possess spore-bearing structures (gymnothecia). The appendages of U. uncinatus are thick and wide to the distal end, unlike that of U. reesii, which taper to a point.
References
Onygenales
Fungi described in 1985
Fungus species | Uncinocarpus uncinatus | [
"Biology"
] | 204 | [
"Fungi",
"Fungus species"
] |
59,143,611 | https://en.wikipedia.org/wiki/Uncinocarpus%20orissi | Uncinocarpus orissi is a species of microfungus that grows on dung and other keratinous materials, such as hair. It was the third species to be designated as part of the genus Uncinocarpus by Canadian mycologists Lynne Sigler, Arlene Flis and J.W. Carmichael in 1998 as a synonym for Pseudoarachniotus orissi and Aphanoascus orissi.
Description
In culture, colonies of U. orissi are yellowish white in colour before darkening to buff or brownish-orange. Colonies are flat, dense and take on a woolly to coarsely powdery texture. U. orissi degrades keratin relatively quickly. U. orissi has a heterothallic mating system, requiring two compatible "sexes" for sexual reproduction to occur. It produces urease enzyme, allowing it to convert urea to ammonia and carbon dioxide. Unlike many other members of the genus Uncinocarpus, U. orissi are lacking in appendages.
As of 2002, U. orissi has been implicated in three recorded infections: one deep-skin infection and two pulmonary infections.
References
Onygenales
Fungi described in 1998
Fungus species | Uncinocarpus orissi | [
"Biology"
] | 257 | [
"Fungi",
"Fungus species"
] |
59,144,574 | https://en.wikipedia.org/wiki/Graph%20%28Unix%29 | In Unix, graph is a command-line utility used to draw plots from tabular data.
History
The graph utility, written by Douglas McIlroy, was present in the first version of Unix, and every later version, for instance:
Unix Version 7, released in 1979
SunOS 5.10, the Solaris version released in 2005
Its output is a sequence of commands for the plot utility, which creates plots using ASCII graphics.
This design demonstrates the Unix philosophy: defining the plot (graph) and drawing it (plot) are separate tools, so they can be recombined with other tools. For instance, plot can be substituted with a different utility, that accepts the same plot commands, but creates the plot in a graphics file format, or sends it to a plotter.
Unix v7 also provided device drivers for plotting the results to various graphics devices;
this was announced as now standard.
The GNU plotutils package provides a free non-exact reimplementation, available for Linux and many other systems.
It can create plots in various graphics formats.
Usage
In its simplest use, the graph utility takes a textfile containing pairs of numbers, indicating the points of a line plot.
It outputs the line plot. Several options can be supplied to modify its behavior.
Example (Unix)
These screenshots demonstrate basic operation on SunOS 5.10, on which graph and plot come preinstalled.
The example input is from the first example in the GNU plotutils manual.
Example (GNU plotutils)
These screenshots demonstrate the GNU plotutils version of graph when run in an xterm, exploiting xterm's ability to emulate a Tektronix 4010 plotter.
This demo was run on Ubuntu, which makes GNU plotutils available as an optional package; many other Linux distributions and other Unix-like systems do the same.
References
External links
Command-line software
Unix software | Graph (Unix) | [
"Technology"
] | 402 | [
"Command-line software",
"Computing commands"
] |
59,144,735 | https://en.wikipedia.org/wiki/Apache%20Helix | Apache Helix is an open-source cluster management framework developed by the Apache Software Foundation.
History
Helix is one of the several notable open source projects developed by LinkedIn. It is a stable cluster management framework used for the automatic management of partitioned, replicated and distributed resources hosted on a cluster of systems.
Helix is one of several notable cluster management framework originally developed by LinkedIn apart from Apache Samza, Apache Kafka and Voldemort. The origins of Helix lie in a distributed NoSQL called Espresso.
Enterprises that use Apache Helix
The following is a list of notable enterprises that have used or are using Helix:
LinkedIn
Yahoo
Uber
Instagram
Pinterest
Airbnb
See also
Cluster management
References
External links
Official Website
LinkedIn software
Helix
Enterprise application integration
Free software programmed in Scala
Java platform
Message-oriented middleware
Service-oriented architecture-related products
Software using the Apache license
2011 software | Apache Helix | [
"Technology"
] | 184 | [
"Computing platforms",
"Java platform"
] |
59,146,042 | https://en.wikipedia.org/wiki/Accuracy%20paradox | The accuracy paradox is the paradoxical finding that accuracy is not a good metric for predictive models when classifying in predictive analytics. This is because a simple model may have a high level of accuracy but too crude to be useful. For example, if the incidence of category A is dominant, being found in 99% of cases, then predicting that case is category A will have an accuracy of 99%. Precision and recall are better measures in such cases.
The underlying issue is that there is a class imbalance between the positive class and the negative class. Prior probabilities for these classes need to be accounted for in error analysis. Precision and recall help, but precision too can be biased by unbalanced class priors in the test sets.
Example
For example, a city of 1 million people has ten terrorists. A profiling system results in the following confusion matrix:
Even though the accuracy is ≈ 99.9%, 990 out of the 1000 positive predictions are incorrect. The precision of = 1% reveals its poor performance. As the classes are so unbalanced, a better metric is the F1 score = ≈ 2% (the recall being = 1).
Literature
Kubat, M. (2000). Addressing the Curse of Imbalanced Training Sets: One-Sided Selection. Fourteenth International Conference on Machine Learning.
See also
False positive paradox
References
Statistical paradoxes | Accuracy paradox | [
"Mathematics"
] | 280 | [
"Mathematical problems",
"Statistical paradoxes",
"Mathematical paradoxes"
] |
59,146,760 | https://en.wikipedia.org/wiki/Adelholzener%20Alpenquellen | Adelholzener Alpenquellen GmbH is the largest mineral spring in Bavaria and is situated in Bad Adelholzen, a district of Siegsdorf. The largest and only shareholder is the Covenant of the Merciful Sisters of St. Vincent de Paul and the company bottles around 580 million mineral water products every year.
History
Around the year 280 AD, according to legend, the spa of Bad Adelholzen was discovered by the Roman preacher St. Primus. On his return to Rome, he was captured along with his brother Felicianus by butchers of Emperor Diocletian and killed. The name of the healing spring is still traced back to the Roman martyr. According to the legend of the saints, Primus, in addition to teaching people in the Christian faith, also healed the sick through prayer and with the restorative power of water.
In the 10th century, the spring came into the possession of the archbishops of Salzburg.
In 1875, the Adelholzener spring water was first sold and by 1895, the mineral water was being shipped nationwide. At the beginning of the 20th century, the spa and bathing business in Bad Adelholzen went bankrupt and in 1907, the Congregation of the Sisters of Mercy of St. Vinzenz von Pau, based in Munich, acquired the spa and bottling plants. In the following years, the production and administration business was modernized and expanded. In 1919, the first electric bottling plant was completed.
After the Second World War in 1946 the place was awarded the official recognition as a spa by the Bavarian State Ministry of the Interior.
In 1994, the business was renamed Adelholzener Alpen and two years later, built a new warehouse and administrative building. In 1998, the company began using its first returnable polyethylene terephthalate (PET) bottling plant and in 2001 was the company launched their oxygenated water range, Active O2, in Germany which was accompanied by the brand's first television commercial.
In 2013, a new glass bottling plant was built, with a capacity of up to 28,000 bottles per hour and four years later, Adelholzener's seventh bottling line was opened with a capacity of 35,000 reusable PET bottles per hour. The company has a market presence in more than 20 countries, the largest market being in Germany and Japan. The profit made from the mineral water is used to support charities and social institutions around Bavaria through the work of the Covenant.
Sponsorship
Adelholzener had sponsored Sauber Formula 1 cars from 2003 to 2005, including on the cars of Felipe Massa, Nick Heidfeld and Jacques Villeneuve.
Adelholzener is also an official sponsor of FC Bayern Munich and is a partner of the BR-Radltour, a German cycling event, providing water for the participants.
References
Mineral water
Bottled water brands
Companies based in Bavaria
Traunstein (district) | Adelholzener Alpenquellen | [
"Chemistry"
] | 597 | [
"Mineral water"
] |
59,146,901 | https://en.wikipedia.org/wiki/List%20of%20pamphlet%20wars | This is a list of pamphlet wars in history. For several centuries after the printing press became common, people would print their own ideas in small pamphlets somewhat akin to modern blogs. While these could not be widely available via the internet they could "go viral", because others were free to reprint pamphlets they liked, and therefore ideas were widely spread. Counter-arguments would then be printed in opposing pamphlets, which might become popular themselves. A prolonged debate carried out this way changed society many times, until copyright laws effectively banned the propagation of ideas in this way.
1517 — The Protestant Reformation — Martin Luther's 95 Theses is simply the most famous salvo in a prolonged pamphlet war that ended up triggering the secession of much of Europe from the Catholic Church (and later reform of that organization), after similar efforts had failed in the past without the printing press to support them.
1640 — Bishops' Wars — John Milton participated in antiprelatical pamphlet wars, opposing the policies of William Laud.
1642 — The English Civil War — Much of the buildup to the actual civil war was driven by an extensive, often heated, debate via pamphlet.
1654 — The Nature of Free Will — Thomas Hobbes and John Bramhall engaged in an intense debate over the nature of free will in humanity.
1655 — Resettlement of the Jews in England — The legalization of the open practice of Judaism in England resulted in a pamphlet war, which because of its civil and abstract nature is sometimes credited as preventing the growth of antisemitism during the debate. This featured Puritan William Prynne writing in opposition and Margaret Fell, a founder of the Religious Society of Friends (Quakers) in support of liberalization.
1680 — The Popish Plot — An invented controversy used to drum up anti-Catholic hysteria in England and Scotland.
1688 — The Socinian controversy — A debate on christology by Church of England theologians. John Locke was a notable participant.
1697 — Nonconformity — Daniel Defoe was eventually imprisoned by Queen Anne as a nonconformist who had advocated for her predecessor, William III during a pamphlet war over his policies, including the arguably illegal maintenance of a standing army during peacetime, widely recognized as a threat to liberty, but defended by .
1707 — Queen Anne's Governor — A pamphlet war in Boston, criticizing Queen Anne's choice of governor for the Massachusetts Bay Colony, a proxy attack criticizing Queen Anne's War.
1721 — Bank of Ireland Charter — One of the many rhetorical conflicts in which Jonathan Swift took part, attacking what he and Daniel DeFoe called "air money", certificates of gold or land deposits being used like paper money by the Bank of Ireland.
1764 — The Paxton Boys — Tension over a failure to protect a frontier village from tribal aggression peaked with a massacre of innocent Conestoga Indians. After Ben Franklin interceded, the conflict was primarily conducted through pamphleteering, which is seen by some as having proved a non-violent alternative to the previous violence.
1765 — The Stamp Act — A tax imposed on the American colonies after the Seven Years' War sparked a pamphlet war that helped set the terminology and arguments for the American Revolution a decade later.
1776 — The American Revolution — Progress toward secession from the British Empire was based primarily on debates carried out in pamphlet form, including outrage over the Boston Massacre and also the crucial publication that swung sentiment from reform to secession, Common Sense.
1787 — Federalism — In the US, the most famous pamphlet war was probably the debate over the US Constitution, between The Federalist Papers and The Anti-Federalist Papers, the former including James Madison, John Adams, and Alexander Hamilton, the latter George Clinton (writing as Cato), Melancton Smith (writing as Brutus), and Richard Henry Lee (writing as the Federal Farmer).
1789 — The Revolution Controversy — A literary struggle in England over how to view the French Revolution, and what it meant about monarchy and the right of self-determination, in general. This debate involved Thomas Paine, William Godwin, Mary Wollstonecraft, Edmund Burke, and Richard Price
1809 — Christian Missions in India — A debate over the acceptability of British Christians attempting to convert colonies ruled by the empire, a practice that went against the tradition of non-interference in local religions.
References
Political debates
Propaganda
Pamphlets
Social media
pamphlet | List of pamphlet wars | [
"Technology"
] | 883 | [
"Computing and society",
"Social media"
] |
59,147,142 | https://en.wikipedia.org/wiki/HD%20186302 | HD 186302 (also designated HIP 97507) is a star in the constellation of Pavo. It is away from Earth, with an apparent magnitude of 8.76. It was identified in November 2018 as a potential solar sibling to the Sun. Similar in spectrum and size, it was suspected to have formed in the same stellar nursery as the Sun 4.6 billion years ago. However, a common origin with the Sun was found to be unlikely in a 2019 paper, as HD 186302's galactic orbit is very different from the Sun's.
See also
HD 162826; the first star identified as a solar sibling in February 2014, in Hercules.
References
Solar twins
G-type main-sequence stars
186302
097507
J19490644-7011167
Pavo (constellation) | HD 186302 | [
"Astronomy"
] | 171 | [
"Constellations",
"Pavo (constellation)"
] |
59,147,706 | https://en.wikipedia.org/wiki/NGC%203810 | NGC 3810 is a spiral galaxy located in the constellation Leo. It is about 50 million light years from Earth, and estimated to be about 60,000 light years in diameter. William Herschel discovered it on 15 March 1784.
The bright galaxy NGC 3810 demonstrates spiral structure similar to that of Messier 77. The central part of the galaxy disk is of high surface brightness and features tightly wound spirals. Outside this disk lie more open arms with lower surface brightness. The bright central region is thought to be forming many new stars and is outshining the outer areas of the galaxy by some margin. Further out, the galaxy displays strikingly rich dust clouds along its spiral arms. Hot young blue stars show up in giant clusters far from the centre and the arms are also littered with bright red giant stars.
NGC 3810 forms a small group of galaxies with NGC 3773, the NGC 3810 Group, which is part of the Virgo Supercluster.
Supernovae
Three supernovae have been observed in NGC 3810:
SN 1997dq (type Ib, mag. 15) was discovered by Masakatsu Aoki on 2 November 1997.
SN 2000ew (type Ic, mag. 14.9) was discovered by Tim Puckett and Alex Langoussis on 28 November 2000.
SN 2022zut (typeIa, mag. 12.8) was discovered by ATLAS on 9 November 2022.
See also
List of NGC objects (3001–4000)
Gallery
References
External links
Unbarred spiral galaxies
Leo (constellation)
3810
06644
036243
Astronomical objects discovered in 1784
Discoveries by William Herschel
+02-30-010
11383+1144 | NGC 3810 | [
"Astronomy"
] | 351 | [
"Leo (constellation)",
"Constellations"
] |
59,147,889 | https://en.wikipedia.org/wiki/Carla%20Cotwright-Williams | Carla Denise Cotwright-Williams (born November 6) is an American mathematician who works as a Technical Director and Data Scientist for the United States Department of Defense. She was the second African-American woman to earn a doctorate in mathematics at the University of Mississippi.
Early life and educational
She is the daughter of a police officer and grew up in South Central Los Angeles. Moving to a better neighborhood in Los Angeles as a teenager. She went to Westchester High School and attended summer enrichment programs for underrepresented students there that included courses at the University of California, Los Angeles, and a field trip to see the Space Shuttle at NASA's Armstrong Flight Research Center on Edwards Air Force Base. She graduated in 1991.
As an undergraduate at California State University, Long Beach, Cotwright-Williams started in engineering. Then, as a math major, she struggled initially and earned low enough grades to be academically disqualified from the university, but worked hard to return as a student in good standing, eventually earning a bachelor's degree in mathematics in 2000. She then earned a master's degree in mathematics from Southern University in Baton Rouge, Louisiana, in 2002.
Initially intending to follow a science & math Ph.D. track, she was persuaded to shift to pure mathematics under the mentorship of an African-American professor, Stella R. Ashford, who became the supervisor for her master's thesis in number theory, Unique Factorization in Bi-Quadratic Number Fields.
She went on to doctoral studies at the University of Mississippi, where she became president of the Graduate Student Council
and earned a second master's degree there along the way in 2004.
She completed her Ph.D. at the University of Mississippi in 2006. Her dissertation was supervised by T. James Reid and concerned matroid theory.
She was the second African-American woman to earn a doctorate in mathematics at the university, and was part of a group of four African-Americans who all graduated in the same year.
Career
After completing her doctorate, Cotwright-Williams worked as a tenure-track faculty member in mathematics at Wake Forest University, Hampton University, and Norfolk State University. While working there, in an effort to shift her career to a government track, she began studying public policy and working on collaborative research on Bayesian network based drone control systems with NASA, and on a US Navy project involving measurement uncertainty. In 2010, she completed a Graduate Certificate in Public Policy Analysis at Old Dominion University. She applied for an American Mathematical Society Congressional Fellowship, and was turned down on her first application but succeeded in her second, in 2012.
Cotwright-Williams also became a 2012–2013 Legislative Branch Fellow, under the American Association for the Advancement of Science Science and Technology Policy Fellowship program. She also worked as a science and technology Fellow for both the Senate and the House of Representatives. While a Congressional Fellow she worked as a staffer on the majority staff of the U.S. Senate Homeland Security and Governmental Affairs Committee and her responsibilities included responding to the Boston Marathon bombing in 2013. In 2014 she worked on data quality for United States Citizenship and Immigration Services, and in 2015 she became Hardy-Apfel IT Fellow at the Social Security Administration. Her work at the Social Security Administration has included business analytics to prevent fraud and support data warehousing.
In 2018, with the fellowship expiring, she moved again to the United States Department of Defense as a data scientist.
Cotwright-Williams continues to hold an adjunct professorial lecturer position in mathematics and statistics at American University. She serves as an at-large member of the executive committee of the Association for Women in Mathematics (AWM).
Her career advice includes the following quote: "Get out and talk to people and learn new things!"
Awards and honors
Outside of Academia Member in the National Association of Mathematicians
Black History Month 2017 Honoree, Mathematically Gifted & Black
References
1973 births
Living people
21st-century American mathematicians
African-American mathematicians
African-American women mathematicians
Combinatorialists
California State University, Long Beach alumni
Southern University alumni
University of Mississippi alumni
Wake Forest University faculty
Hampton University faculty
Norfolk State University faculty
American University faculty
21st-century American women mathematicians
21st-century American women academics
21st-century American academics
21st-century African-American women
21st-century African-American scientists
20th-century African-American people
20th-century African-American women | Carla Cotwright-Williams | [
"Mathematics"
] | 879 | [
"Combinatorialists",
"Combinatorics"
] |
50,543,273 | https://en.wikipedia.org/wiki/DENIS%20J082303.1%E2%88%92491201 | DENIS-P J082303.1-491201 (also known as DENIS J082303.1-491201, DE0823-49), is a binary system of two brown dwarfs, located from Earth. The system is located in the constellation Vela.
The primary has a spectral class of L1.5, a mass of and a temperature of . The secondary is also a brown dwarf but with a spectral type of L5.5, a mass of , and a temperature of . The mass ratio is around 0.64 to 0.74.
The system has an orbital period of 248 days. The age of the system is estimated to be around 80 to 500 million years old, a relatively young object in the solar neighbourhood, however it does not seem to have any association with any moving groups.
DENIS J082303.1-491201 was discovered in 2007 by Ngoc Phan-Bao et al as part of the Deep Near Infrared Survey of the Southern Sky or DENIS for short.
Planetary system
A substellar companion, DENIS-P J082303.1−491201 b was discovered in 2013 and included in the NASA Exoplanet Archive as the first exoplanet discovered by the Astrometry exoplanet detection method.
References
Brown dwarfs
L-type brown dwarfs
Binary stars
J08230313-4912012
Vela (constellation)
Planetary systems with one confirmed planet | DENIS J082303.1−491201 | [
"Astronomy"
] | 308 | [
"Vela (constellation)",
"Constellations"
] |
50,543,416 | https://en.wikipedia.org/wiki/Hyperpolarized%20carbon-13%20MRI | Hyperpolarized carbon-13 MRI is a functional medical imaging technique for probing perfusion and metabolism using injected substrates.
It is enabled by techniques for hyperpolarization of carbon-13-containing molecules using dynamic nuclear polarization and rapid dissolution to create an injectable solution. Following the injection of a hyperpolarized substrate, metabolic activity can be mapped based on enzymatic conversion of the injected molecule. In contrast with other metabolic imaging methods such as positron emission tomography, hyperpolarized carbon-13 MRI provides chemical as well as spatial information, allowing this technique to be used to probe the activity of specific metabolic pathways. This has led to new ways of imaging disease. For example, metabolic conversion of hyperpolarized pyruvate into lactate is increasingly being used to image cancerous tissues via the Warburg effect.
Hyperpolarization
While hyperpolarization of inorganic small molecules (like 3He and 129Xe) is generally achieved using spin-exchange optical pumping (SEOP), compounds useful for metabolic imaging (such as 13C or 15N) are typically hyperpolarized using dynamic nuclear polarization (DNP). DNP can be performed at operating temperatures of 1.1-1.2 K, and high magnetic fields (~4T). The compounds are then thawed and dissolved to yield a room temperature solution containing hyperpolarized nuclei which can be injected.
Dissolution and injection
Hyperpolarized samples of 13C pyruvic acid are typically dissolved in some form of aqueous solution containing various detergents and buffering reagents. For example, in a study detecting tumor response to etoposide treatment, the sample was dissolved in 40 mM HEPES, 94 mM NaOH, 30 mM NaCl, and 50 mg/L EDTA.
Preclinical models
Hyperpolarized carbon-13 MRI is currently being developed as a potentially cost effective diagnostic and treatment progress tool in various cancers, including prostate cancer. Other potential uses include neuro-oncological applications such as the monitoring of real-time in vivo metabolic events.
Clinical trials
The majority of clinical studies utilizing 13C hyperpolarization are currently studying pyruvate metabolism in prostate cancer, testing reproducibility of the imaging data, as well as feasibility of acquiring time.
Imaging methods
Spectroscopic imaging
Spectroscopic imaging techniques enable chemical information to be extracted from hyperpolarized carbon-13 MRI experiments. The distinct chemical shift associated with each metabolite can be exploited to probe the exchange of magnetization between pools corresponding to each of the metabolites.
Metabolite-selective excitation
Using techniques for simultaneous spatial and spectral selective excitation, RF pulses can be designed to perturb metabolites individually.
This enables the encoding of metabolite-selective images without the need for spectroscopic imaging. This technique also allows different flip angles to be applied to each metabolite,
which enables pulse sequences to be designed that make optimal use of the limited polarization available for imaging.
Dynamic imaging models
In contrast with conventional MRI, hyperpolarized experiments are inherently dynamic as images must be acquired as the injected substrate spreads through the body and is metabolized. This necessitates dynamical system modelling and estimation for quantifying metabolic reaction rates. A number of approaches exist for modeling the evolution of magnetization within a single voxel.
Two-species model with unidirectional flux
The simplest model of metabolic flux assumes unidirectional conversion of the injected substrate S to a product P. The rate of conversion is assumed to be governed by the reaction rate constant
Exchange of magnetization between the two species can then be modeled using the linear ordinary differential equation
where denotes the rate at which the transverse magnetization decays to thermal equilibrium polarization, for the product species P.
Two-species model with bidirectional flux
The unidirectional flux model can be extended to account for bidirectional metabolic flux with forward rate and backward rate
The differential equation describing the magnetization exchange is then
Effect of radio-frequency excitation
Repeated radio-frequency (RF) excitation of the sample causes additional decay of the magnetization vector. For constant flip angle sequences, this effect can be approximated using a larger effective rate of decay computed as
where is the flip angle and is the repetition time.
Time-varying flip angle sequences can also be used, but require that the dynamics be modeled as a hybrid system with discrete jumps in the system state.
Metabolism mapping
The goal of many hyperpolarized carbon-13 MRI experiments is to map the activity of a particular metabolic pathway. Methods of quantifying the metabolic rate from dynamic image data include temporally integrating the metabolic curves, computing the definite integral referred to in pharmacokinetics as the area under the curve (AUC), and taking the ratio of integrals as a proxy for rate constants of interest.
Area-under-the-curve ratio
Comparing the definite integral under the substrate and product metabolite curves has been proposed as an alternative to model-based parameter estimates as a method of quantifying metabolic activity. Under specific assumptions, the ratio
\frac{AUC(P)}{AUC(S)}
of area under the product curve AUC(P) to the area under the substrate curve AUC(S) is proportional to the forward metabolic rate .
Rate parameter mapping
When the assumptions under which this ratio is proportional to are not met, or there is significant noise in the collected data, it is desirable to compute estimates of model parameters directly. When noise is independent and identically distributed and Gaussian, parameters can be fit using non-linear least squares estimation. Otherwise (for example if magnitude images with Rician-distributed noise are used), parameters can be estimated by maximum likelihood estimation. The spatial distribution of metabolic rates can be visualized by estimating metabolic rates corresponding to the time series from each voxel, and plotting a heat map of the estimated rates.
See also
Carbon-13 nuclear magnetic resonance
Dynamic nuclear polarization
Functional imaging
Magnetic resonance spectroscopic imaging
References
Magnetic resonance imaging | Hyperpolarized carbon-13 MRI | [
"Chemistry"
] | 1,262 | [
"Nuclear magnetic resonance",
"Magnetic resonance imaging"
] |
50,544,498 | https://en.wikipedia.org/wiki/Sorter%20%28logistics%29 | In logistics, a sorter is a system which performs sortation of products (goods, luggage, mail, etc.) according to their destinations.
A common type of sorter is a conveyor-based system. While they may be based on other conveyor systems, usually sorters are unique types of conveyors.
Sortation is the process of identifying items on a conveyor system, and diverting them to specific destinations. Sorters are applied to different applications depending upon the product and the requested rate.
Common elements of sorters
A feeder system whose sole purpose to feed the products into the sorter in proper orientation and with proper spacing, so that the sorter could operate correctly.
Another common element are receptacles which receive the products as they leave the sorter towards a proper destination. Receptacles may be as simple as chutes, or gravity conveyors, or powered conveyors.
Sorter types
There is a number of typical sorter designs.
Cross belt sorter
Paddle sorter
Pop-up transfer sorter
Lineshaft pop-up wheel sorter
Pop-up steerable roller sorter
Pusher or puller sorter
Parcel Singulator
Line Sorter
Shoe sorter
Slide tray sorter
Split tray sorter (bomb-bay sorter)
Tilt tray sorter
References
Logistics
Industrial machinery | Sorter (logistics) | [
"Engineering"
] | 269 | [
"Industrial machinery"
] |
50,544,500 | https://en.wikipedia.org/wiki/Cross%20belt%20sorter | A cross-belt sorter is an advanced conveyor-based automated sortation system used in various industries to handle and direct items such as luggage, apparel, parcels, packages, and mail. This system uses a series of independently operated short conveyor belts mounted transversely along the main track , known as cross-belts that are organised in a loop, to sort items quickly and accurately to their designated destinations. Cross-belt sorters are widely utilised in logistics, e-commerce and postal services due to their high efficiency, throughput, and accuracy.
Types of cross belt sorters
There are a variety of different cross-belt sorters—each industry and each cross-belt sorter manufacturer can have unique products. Nevertheless, the standard two are horizontal cross-belt sorters and vertical cross-belt sorters. In both cases, current generations employ linear induction motor technology—this means they are simpler to operate, maintain, and endure less mechanical wear over time.
Components and Operation
The main components of a cross-belt sorter include:
Induction Area: This is where items are introduced onto the sorter. Items are predominantly fed automatically from conveyor belts, or other feeding mechanisms, although as an exception, some are fed manually by an operator at low speeds.
Track: The track guides the trains along a predefined path. There are two main types of track (or rail) configuration; Horizontal or Vertical. Although referred to as a horizontal loop, this track can have inclined and decline sections to reach different heights, however, the track curves are usually on the horizontal plane and the closed loop can contain many turns. This sorter configuration also allows for recirculation – A term that refers to items that can remain on the sorter loop without needing to be ejected. This is useful should a discharge point not be available. A vertical loop has no horizontal track curves, and items are only transported in one direction and horizontal plane from one induction area. This configuration limits throughput compared to a horizontal sorter, but provides cross-belt sortation within a smaller area. As all items must be ejected before the cross-belt makes its return journey to the induct area, there is no recirculation on the sorter possible.
Train: A group of carriers is called a train. For redundancy, there are typically a number of trains joined end-to-end to form one continuous loop. If one train loses communication, the availability of the sorter is therefore kept.
Carrier: These wheeled units are joined to each other to form a train.
Cells: These are the individual conveyor belts mounted on top of a carrier. Each cross-belt cell has its own motor or actuation and can move items perpendicular to the direction of travel, either to the left or right, enabling the precise direction of items to specific slides, chutes or conveyors. A carrier can carry one or more cells.
Control System: A sophisticated control system, often integrated with sensors and software, manages the sorting process. It identifies each item, determines its destination, and activates the appropriate cross-belt at the right moment.
Discharge Points: This is where items are ejected from the sorter, typically for a specific destination. They can be bins, chutes, conveyor belts, or directly into transportation containers.
How It Works
The cross-belt sorter operates in several stages:
Induction: Items are fed typically at an angle of 30˚ or 45˚ onto the moving sorter through a series of conveyors that accelerate the item to the sorter speed. The cross-belt then activates and the item is inducted to the sorter cell at null relative speed. The inducted item can occupy one or more cells depending on its size, weight and carrier configuration
Scanning: Typically after induction, the item requires identification to know the correct discharge point on the sorter. This can involve OCR, barcode readers, RFID scanners, or other identification. Depending on application, this can also be performed before or during the induction
Sorting: As items travel along the track, the control system assigns each item to a discharge point depending on the scanning information. When the item reaches the designated discharge point, the cross-belt cell activates and moves the item to the appropriate chute or conveyor
Discharge: Sorted items are discharged into their respective bins, chutes, or conveyors. These can then be processed further or prepared for shipping
Technology
There are typically three main connections required to the cross-belt trains to enable operation. High-end cross-belt sorters adopt non-contact technology in favour of minimal maintenance. This means little or no wear occurs, providing a highly reliable system and reducing lifecycle cost, but results in a slightly higher capital cost to other technologies.
Means to propel the carriers
Linear synchronous motors (LSM) are used in high-end sorters as they require little maintenance, are non-contact and can provide accurate acceleration, deceleration or maintain a speed. Although speeds up to 3m/s are reported, sorter speeds of up to 2.5m/s are typically used for parcel applications to ensure no fly-outs of lighter items (Items becoming airborne during acceleration or transit). Additional LSM’s are typically added to a track for redundancy, therefore, should a LSM become inactive, there is sufficient propulsion provided by the remaining LSM’s to ensure no loss of performance.
Alternative contact solutions adopt motorised wheels that propel a flat plate under the sorter through friction.
Means to activate the Cells
Inductive power transfer (IPT) uses a magnetic field to transfer electrical energy without contact. Alternatively, a wheel with a motor on the carrier, generates power to the cells. An often cheaper but higher maintenance solution uses a Busbar system and brushes.
Contact types of activation rely on mechanical actuators to activate the cells, though typically the ejection point requires to be a fixed position resulting in less dynamic ejections and operates at lower speeds and throughputs.
Means to communicate with the control system
Industrial Wi-Fi is typically used as this provides non-contact communication that is not disrupted by dirt or debris. Alternative technologies include Infrared.
Advantages
Cross-belt sorters offer several advantages:
Gentle Handling: The sorter does not rely on gravity to discharge items, such as a tilt-tray. This means ejection is better controlled and reliable.
Chute density: Divert points can be closer together so increasing chute density, resulting in better space utilisation.
Low operating costs: Depending on the technology used, low operating costs can be achieved through a combination of low maintenance and high energy efficiency.
High throughput: Capable of sorting thousands of items per hour, cross-belt sorters significantly enhance throughput and efficiency. In addition, the throughput can be multiplied for horizontal sorters by adding additional virtual induction areas, similar to having a chain of sorters back-to-back. For instance, with 3 induct areas, each with a throughput of 12000 parcels per hour, it will equate as 36000 parcels per hour sorted (assuming all parcels leave the sorter before the next induction area).
Accuracy: With precise control and advanced scanning technology, these systems achieve high accuracy in sorting. Some cross-belts can also dynamically adjust the ejection point to better fill a chute or based on size or weight characteristics
Flexibility: Suitable for handling a wide range of item sizes, shapes, and weights, and tricky items such as polybags, making them versatile for various industries.
Scalability: Modular designs allow for easy expansion and customization to meet growing operational demands.
Applications
Cross-belt sorters are employed in various sectors, including:
E-commerce: To handle the high volume of orders and returns, ensuring timely delivery and efficient processing.
Postal Services: For sorting mail and parcels quickly and accurately to improve delivery times.
Retail Distribution: In distribution centres to sort products for shipment to stores or directly to customers.
Airport Baggage Handling: For efficiently sorting and directing luggage to the appropriate flights or terminals.
References
Logistics
Industrial machinery | Cross belt sorter | [
"Engineering"
] | 1,651 | [
"Industrial machinery"
] |
50,546,524 | https://en.wikipedia.org/wiki/TYC%209486-927-1 | TYC 9486-927-1 (also known as 2MASS J21252752-8138278) is the primary of a possible trinary star system located at a distance of 34.5 parsecs from Earth in the southern direction in the constellation of Octans. It is a BY Draconis variable, with large starspots causing it to change brightness as it rotates every 13 hours.
TYC 9486-927-1 has rapid rotation and coronal and chromospheric activity suggestive of a young age. Observations and multi-epoch radial velocity data suggest that TYC 9486-927-1 is a single, rapidly rotating star rather than a spectroscopic or tight visual binary. However, it is still possible that TYC 9486-927-1 is an equal mass binary with a face-on orbit and close separation.
The candidate secondary stellar companion is 2MASS J21121598–8128452. It is a red dwarf star of spectral class M5.5. Its projected separation from the primary would be 62,700 AU. The candidate tertiary companion is 2MASS J21192028–8145446 - of spectral class M6 or M7 and at a projected separation of 31,000 AU from the primary.
Planetary system
The planet 2MASS J21265040-8140293 orbits TYC 9486-927-1 at a projected separation of . With a mass from 11.6 to 15 Jupiter masses, it is considered to be either a brown dwarf, or a giant planet.
References
Octans
J21252752-8138278
Planetary systems with one confirmed planet
M-type main-sequence stars
3
Octantis, FT | TYC 9486-927-1 | [
"Astronomy"
] | 368 | [
"Octans",
"Constellations"
] |
50,546,640 | https://en.wikipedia.org/wiki/Cortinarius%20kioloensis | Cortinarius kioloensis is a fungus native to Australia. It was described in 2009 by Alec Wood, and is related to the Northern Hemisphere species Cortinarius violaceus.
Taxonomy
The type specimen was collected along Higgins Creek in Kioloa State Forest near Batemans Bay in southern New South Wales on 22 June 1980. The species was one of only twelve placed in the Cortinarius subgenus Cortinarius, along with Cortinarius violaceus.
Description
The fruit body has a wide dark violet cap that is convex and becomes flattish with a low, wide boss as it matures. The cap surface is dry and covered with fine scales or hair. This layer on the cap is known as the pileipellis, which is classified as a trichoderm—having parallel hyphae running perpendicular to the surface and forming a layer 8–20 μm wide. The cap colour is lighter towards the cap margin, which is entire and can split or become wavy in older specimens. The flesh is dark purple to black. All mushroom parts stain red in potassium hydroxide. The thick wide dark blue gills are sinuate. The pale violet stipe is high and wide at the top and wide at the base, which is bulbous. The stipe turns dark blue when handled or touched because of the violet universal veil. The mycelium is pale violet. The very warty oval spores are 10.5–14 μm long by 6.5–9 μm wide. The mushroom has no strong aroma.
Geography and habitat differences allow it to be distinguished from similar species: the otherwise identical Cortinarius atroviolaceus is found in montane rainforest in Malaysia while Cortinarius atrolazulinus and Cortinarius carneipallidus occur with Nothofagaceae in New Zealand. Cortinarius jenolanensis has a smooth cap. Cortinarius austroviolaceus has less warty spores.
Ecology
The fruit bodies of Cortinarius kioloensis appear in autumn and winter (April to July) under Eucalyptus and Allocasuarina in southeastern Australia and Tasmania, and in association with Leptospermum in New Zealand. In New South Wales it has been collected from along Gore Creek in Lane Cove Bushland Park, Royal National Park (Couranga Track), Boronia Park, Bradleys Head, Scotland Island and Hazelbrook and Sassafras Gully near Springwood in the Blue Mountains.
See also
List of Cortinarius species
References
External links
kioloensis
Fungi described in 2009
Fungi native to Australia
Fungi of New Zealand
Fungus species | Cortinarius kioloensis | [
"Biology"
] | 541 | [
"Fungi",
"Fungus species"
] |
50,546,680 | https://en.wikipedia.org/wiki/Distributed%20tree%20search | Distributed tree search (DTS) algorithm is a class of algorithms for searching values in an efficient and distributed manner. Their purpose is to iterate through a tree by working along multiple branches in parallel and merging the results of each branch into one common solution, in order to minimize time spent searching for a value in a tree-like data structure.
The original paper was written in 1988 by Chris Ferguson and Richard E. Korf, from the University of California's Computer Science Department. They used multiple other chess AIs to develop this wider range algorithm.
Overview
The Distributed Tree Search Algorithm (also known as Korf–Ferguson algorithm) was created to solve the following problem: "Given a tree with non-uniform branching factor and depth, search it in parallel with an arbitrary number of processors as fast as possible."
The top-level part of this algorithm is general and does not use a particular existing type of tree-search, but it can be easily specialized to fit any type of non-distributed tree-search.
DTS consists of using multiple processes, each with a node and a set of processors attached, with the goal of searching the sub-tree below the said node. Each process then divides itself into multiple coordinated sub-processes which recursively divide themselves again until an optimal way to search the tree has been found based on the number of processors available to each process. Once a process finishes, DTS dynamically reassigns the processors to other processes as to keep the efficiency to a maximum through good load-balancing, especially in irregular trees.
Once a process finishes searching, it recursively sends and merges a resulting signal to its parent-process, until all the different sub-answers have been merged and the entire problem has been solved.
Applications
DTS is only applicable under two major conditions: the data structure to search through is a tree, and the algorithm can make use of at least one computation unit (Although it cannot be considered as distributed if there is only one).
One major example of the everyday use of DTS is network routing. The Internet can be seen as a tree of IP addresses, and an analogy to a routing protocol could be how post offices work in the real world. Since there are over 4.3 billion IP addresses currently, society heavily depends on the time the data takes to find its way to its destination. As such, IP-routing divides the work into multiple sub-units which each have different scales of calculation capabilities and use each other's result to find the route in a very efficient manner. This is an instance of DTS that affects over 43% of the world's population, for reasons going from entertainment to national security.
Alternatives
Although DTS is currently one of the most widely used algorithms, many of its applications have alternatives to them which could potentially develop into more efficient, less resource-demanding solutions, were they more researched.
One of the more controversial examples is Big-Data processing. In applications like Google Search Engine, Facebook, YouTube, search needs to be optimized to keep waiting time inside a reasonable window. This could be achieved through the plain use of DTS, but other algorithms are used in place (for example data-hashing in SQL databases), or in conjunction (Facebook's Haystack algorithm groups parallel tree-search, data-hashing and memory-ordering/sorting).
One of the more important limits of DTS is the fact that it requires a tree as input. Trees are a sub-instance of a data structure known as Graphs, which means every Graph can be converted into a tree. Although there currently exists no better way to search through trees than Korf-Ferguson's algorithm, each task has different particularities and in most cases, there will exist more efficient data structures to represent the problem and solve it than through tree-search. And so there exist instances of tree structures with cycles that cannot possibly be faster than a graph-search on the same structure with the same processing power.
Controversy
There are few controversies around Korf-Ferguson's DTS algorithm, since it is recognized as very complete, but simple. It is very often used as a stepping stone for students to discover the fundamentals and key concepts of distributed problem-solving.
The most important challenge to this algorithmic concept was an article by Kröll B, "Balanced Distributed Search Trees Do Not Exist", which does not attack the veracity or current efficiency of the algorithm, but rather the fact that DTS itself, no matter how many improvements are made to it (for example balancing the input tree before-hand), will never be able to reach optimal resolution-time. This opens a new view point: are too many resources used into the completion of DTS, which blocks new algorithms with higher efficiency-potential from getting researched and developed? Another limit of DTS is the fact that no matter how efficient the division, coordination and merging of the solutions is, it will always be limited by the material number or processors and their processing power.
See also
Tree (data structure)
Search tree
Binary search tree
Tree traversal
Monte Carlo tree search
Parallel computing
Colbrook A., Brewer E., Dellarocas C., Weihl W., "Algorithms for Search Trees on Message-Passing Architectures" (1996)
Colbrook A., Smythe C., Efficient implementations of search trees on parallel distributed memory architectures (1990)
Bayer R., McCreight E., Organization and Maintenance of Large Ordered Indices. Acta Informatica 1 (1972)
Comer D., The Ubiquitous B-Tree (1979)
References
Algorithms | Distributed tree search | [
"Mathematics"
] | 1,142 | [
"Applied mathematics",
"Algorithms",
"Mathematical logic"
] |
50,546,713 | https://en.wikipedia.org/wiki/Cortinarius%20hallowellensis | Cortinarius hallowellensis is a fungus native to Western Australia and Tasmania. It was described in 2009 by Alec Wood, and is related to the northern hemisphere species Cortinarius violaceus. The main species in the North America group, Cortinarius monticola, has also been identified, but has not been found in Australia. Despite this relative isolation, there is genetic interchange between the North American species and the Australian species.
See also
List of Cortinarius species
References
External links
hallowellensis
Fungi described in 2009
Fungi native to Australia
Fungus species | Cortinarius hallowellensis | [
"Biology"
] | 120 | [
"Fungi",
"Fungus species"
] |
50,548,026 | https://en.wikipedia.org/wiki/Cortinarius%20carneipallidus | Cortinarius carneipallidus is a fungus native to New Zealand. It was described in 2015 by Emma Harrower and Egon Horak, and is related to the northern hemisphere species Cortinarius violaceus.
See also
List of Cortinarius species
References
External links
carneipallidus
Fungi described in 2015
Fungi of New Zealand
Taxa named by Egon Horak
Fungus species | Cortinarius carneipallidus | [
"Biology"
] | 86 | [
"Fungi",
"Fungus species"
] |
50,548,112 | https://en.wikipedia.org/wiki/Eugene%20G.%20Munroe | Eugene Gordon Munroe (8 September 1919 – 31 May 2008) was a Canadian entomologist who discovered numerous species of insects. He worked for the Insect Systematics and Biological Control Unit, Entomology Division in Ottawa, Ontario, Canada.
Munroe was "the acknowledged authority on the Pyraloidea worldwide for many years". From 1976 to 1982, he also served as editor-in-chief of Moths of America North of Mexico.
Authored taxa
Taxa named by Eugene G. Munroe
Publications
Monroe published more than 200 papers, including:
Munroe, E.G. 1948: The geographical distribution of butterflies in the West Indies. Ph.D. thesis. Cornell University, Ithaca, New York.
Munroe, E.G. 1959: New Pyralidae from the Papuan Region (Lepidoptera). The Canadian Entomologist, 91(2): 102–112.
Munroe, E.G. 1960: New Tropical Pyraustinae (Lepidoptera: Pyralidae). The Canadian Entomologist, 92(3): 164–173.
Munroe, E.G. 1960a: A New Genus of Pyralidae and its Species (Lepidoptera). The Canadian Entomologist, 92(3): 188–192.
Munroe, E.G., Mutuura, A. 1968: Contributions to a study of the Pyraustinae (Lepidoptera: Pyralidae) of temperate East Asia II. The Canadian Entomologist, 100(8): 861–868.
Munroe, E.G., Mutuura, A. 1968a: Contributions to a study of the Pyraustinae (Lepidoptera: Pyralidae) of temperate East Asia I. The Canadian Entomologist, 100(8): 847–861. doi: 10.4039/Ent100847-8.
Mutuura, A., Munroe, E.G. 1970: Taxonomy and distribution of the European corn borer and allied species: Genus Ostrinia (Lepidoptera: Pyralidae). Memoirs of the Entomological Society of Canada, 112 (supplement 71): 1–112.
Shaffer, J.C. & Munroe, E., 1989. Type Material Of 4 African Species Of Notarcha Meyrick, With Designations Of Lectotypes And Changes In Synonymy (Lepidoptera, Crambidae, Pyraustinae). Proceedings of the Entomological Society of Washington 91: 248-256
Shaffer, J.C. & Munroe, E., 1989. Type material of two Peruvian species of Herpetogramma and one of Pleuroptya (Lepidoptera: Crambidae: Pyraustinae). Proceedings of the Entomological Society of Washington 91: 414-420
References
1919 births
2008 deaths
Canadian entomologists
Taxon authorities
20th-century Canadian zoologists
Presidents of the Entomological Society of Canada
Canadian editors | Eugene G. Munroe | [
"Biology"
] | 618 | [
"Taxon authorities",
"Taxonomy (biology)"
] |
50,549,090 | https://en.wikipedia.org/wiki/Rutgersella | Rutgersella truexi is a form species for problematic fossils of Early Silurian age in Pennsylvania. It has been of special interest because of its morphological similarity with the iconic Ediacaran fossil Dickinsonia, and may have been a late surviving vendobiont.
Description
Rutgersella truexi is a flat, segmented fossil, with both radial and bilateral symmetry like Dickinsonia, but with a shorter midline. The fossils are pyritized; some internal chambers are filled with chalcedony, so that they are preserved along with proposed "basal rhizines".
Controversially, according to Retallack, these observations suggest affinities with lichens, and perhaps the fungal phylum Glomeromycota, a statement not currently supported by more verifiable palaeontologists.
Gallery
References
Silurian fungi
Controversial taxa
Enigmatic prehistoric animal genera
Fossil taxa described in 1968 | Rutgersella | [
"Biology"
] | 189 | [
"Biological hypotheses",
"Controversial taxa"
] |
50,549,349 | https://en.wikipedia.org/wiki/John%20H.%20Eicher | John Harold Eicher () was an organic chemist, philosopher of science, historian, and author. He was a Manhattan Project scientist who worked at Columbia University to develop the first atomic bomb, and taught chemistry at Miami University in Oxford, Ohio, for 37 years. Eicher was the author of several chemistry publications and, with his son David J. Eicher, was coauthor of the reference book Civil War High Commands.
In 2016, Eicher was elected by the State of Ohio to the class of 2016, Ohio Senior Citizens of the Year. He taught for Miami University's Institute for Learning and Retirement for many years, and was a teacher for 75 continuous years, with his first assistant teaching role in 1941 in a mineralogy class at Purdue University.
Early life and education
The product of German, Swiss, and a small amount of Delaware Native American ancestry, Eicher was born in Dayton, Ohio. Eicher's father, Harold Ralph Eicher (1892–1968) was a sales manager and his mother, Myrtle Grace (née Wetzel) Eicher (1894–1989) was a seamstress, public school teacher, and piano and organ teacher.
Eicher attended Fairview Elementary School. Eicher organized a chemical laboratory at his home in Dayton, and practiced chemistry and all aspects of photography with a Leica camera. He studied chemistry at Fairview High School, where he was the laboratory assistant. There, he placed first in the 1938 district scholarship and fourth in Ohio.
At Purdue University in West Lafayette, Indiana, Eicher continued his chemistry studies, obtaining a B.S. degree in 1942. While an undergraduate, he prepared sulfamic acid, used in the preparation of various sulfa drugs at Johns Hopkins University; he collected scrap iron for the war effort. He served as laboratory assistant in mineralogy for the Purdue School of Chemical and Metallurgical Engineering.
Career
Moving to the Ohio State University in Columbus, Eicher helped in the preparation of aviation gasoline components such as triptane, a reference compound, which was sent to the Royal Air Force during the Battle of Britain. He joined the American Chemical Society in 1943, later serving as an assistant secretary and as a councilor.
In mid-1943 Eicher joined the Manhattan Project at Columbia University in New York, working first with Willard Libby (1908–1980), Nobel Laureate in 1960; then with Harold C. Urey (1893–1981), chair of the chemistry department and 1934 Nobel Laureate; with John R. Dunning (1907–1975), dean of engineering; and with Leslie R. Groves (1896–1970), major general, commanding the Manhattan Engineer District. There Eicher worked on the synthesis of fluorocarbons used as lubricants, as plastics such as Teflon. He then worked on pilot plant tests for the enrichment of uranium-235. Finally, Eicher spent two years along with colleague Albert L. Myerson (1919–2004) constructing and operating a gas viscosimeter used to study uranium hexafluoride at various temperatures and pressures, the data from which were used in the production of uranium isotopes at the large gaseous diffusion plant at Oak Ridge, Tennessee.
Returning to Purdue University in 1945 for graduate studies, Eicher taught organic technic and qualitative analysis for six years as an assistant instructor. He became a longtime chapter secretary for the Phi Lambda Upsilon national chemistry honorary, and a member of the research Society of the Sigma Xi. With colleague Alec Kelley (1923–2013), he founded a Unitarian fellowship which later became the Unitarian-Universalist Church of Lafayette, Indiana. Eicher then worked on the preparation of various nitro and oximino compounds to earn his Ph.D. in 1952. One of his dissertation advisors was Herbert C. Brown (1912–2004), 1979 Nobel Laureate. Eicher often visited with his friend Linus C. Pauling (1901–1994), who won two Nobel Prizes, one for chemistry in 1954 and the Peace Prize in 1962.
Eicher joined the chemistry department at Miami University in Oxford, Ohio, in 1952, and he subsequently taught chemistry there for 37 years. In 1953 he organized a student and faculty liberal religious club at Miami which became a Unitarian Fellowship and later evolved into the Hopedale Unitarian-Universalist Community.
Personal life
On June 12, 1957, Eicher married Susan Ann Arne (1923–1983), a sociologist and legal secretary, in Sarasota, Florida. They had two children, Nancy Grace Eicher (1959– ), a journalist and editor, and David John Eicher (1961– ), astronomer and historian.
Eicher and his son David collaborated on a number of books focusing on the American Civil War, including Civil War High Commands.
References
1921 births
2016 deaths
American organic chemists
Manhattan Project people
Writers from Dayton, Ohio
Scientists from Ohio
Columbia University faculty
Miami University faculty
Purdue University alumni
Historians of the American Civil War
Philosophers of science | John H. Eicher | [
"Chemistry"
] | 1,034 | [
"Organic chemists",
"American organic chemists"
] |
50,550,012 | https://en.wikipedia.org/wiki/Biological%20rules | A biological rule or biological law is a generalized law, principle, or rule of thumb formulated to describe patterns observed in living organisms. Biological rules and laws are often developed as succinct, broadly applicable ways to explain complex phenomena or salient observations about the ecology and biogeographical distributions of plant and animal species around the world, though they have been proposed for or extended to all types of organisms. Many of these regularities of ecology and biogeography are named after the biologists who first described them.
From the birth of their science, biologists have sought to explain apparent regularities in observational data. In his biology, Aristotle inferred rules governing differences between live-bearing tetrapods (in modern terms, terrestrial placental mammals). Among his rules were that brood size decreases with adult body mass, while lifespan increases with gestation period and with body mass, and fecundity decreases with lifespan. Thus, for example, elephants have smaller and fewer broods than mice, but longer lifespan and gestation. Rules like these concisely organized the sum of knowledge obtained by early scientific measurements of the natural world, and could be used as models to predict future observations. Among the earliest biological rules in modern times are those of Karl Ernst von Baer (from 1828 onwards) on embryonic development (see von Baer's laws), and of Constantin Wilhelm Lambert Gloger on animal pigmentation, in 1833 (see Gloger's rule).
There is some scepticism among biogeographers about the usefulness of general rules. For example, J.C. Briggs, in his 1987 book Biogeography and Plate Tectonics, comments that while Willi Hennig's rules on cladistics "have generally been helpful", his progression rule is "suspect".
List of biological rules
Allen's rule states that the body shapes and proportions of endotherms vary by climatic temperature by either minimizing exposed surface area to minimize heat loss in cold climates or maximizing exposed surface area to maximize heat loss in hot climates. It is named after Joel Asaph Allen who described it in 1877.
Bateson's rule states that extra legs are mirror-symmetric with their neighbours, such as when an extra leg appears in an insect's leg socket. It is named after the pioneering geneticist William Bateson who observed it in 1894. It appears to be caused by the leaking of positional signals across the limb-limb interface, so that the extra limb's polarity is reversed.
Bergmann's rule states that within a broadly distributed taxonomic clade, populations and species of larger size are found in colder environments, and species of smaller size are found in warmer regions. It applies with exceptions to many mammals and birds. It was named after Carl Bergmann who described it in 1847.
Cope's rule states that animal population lineages tend to increase in body size over evolutionary time. The rule is named for the palaeontologist Edward Drinker Cope.
Deep-sea gigantism, noted in 1880 by Henry Nottidge Moseley, states that deep-sea animals are larger than their shallow-water counterparts. In the case of marine crustaceans, it has been proposed that the increase in size with depth occurs for the same reason as the increase in size with latitude (Bergmann's rule): both trends involve increasing size with decreasing temperature.
Dollo's law of irreversibility, proposed in 1893 by French-born Belgian paleontologist Louis Dollo states that "an organism never returns exactly to a former state, even if it finds itself placed in conditions of existence identical to those in which it has previously lived ... it always keeps some trace of the intermediate stages through which it has passed."
Eichler's rule states that the taxonomic diversity of parasites co-varies with the diversity of their hosts. It was observed in 1942 by Wolfdietrich Eichler, and is named for him.
Emery's rule, noticed by Carlo Emery, states that insect social parasites are often closely related to their hosts, such as being in the same genus.
Foster's rule, the island rule, or the island effect states that members of a species get smaller or bigger depending on the resources available in the environment. The rule was first stated by J. Bristol Foster in 1964 in the journal Nature, in an article titled "The evolution of mammals on islands".
Gause's law or the competitive exclusion principle, named for Georgy Gause, states that two species competing for the same resource cannot coexist at constant population values. The competition leads either to the extinction of the weaker competitor or to an evolutionary or behavioral shift toward a different ecological niche.
Gloger's rule states that within a species of endotherms, more heavily pigmented forms tend to be found in more humid environments, e.g. near the equator. It was named after the zoologist Constantin Wilhelm Lambert Gloger, who described it in 1833.
Haldane's rule states that if in a species hybrid only one sex is sterile, that sex is usually the heterogametic sex. The heterogametic sex is the one with two different sex chromosomes; in mammals, this is the male, with XY chromosomes. It is named after J.B.S. Haldane.
Hamilton's rule states that genes should increase in frequency when the relatedness of a recipient to an actor, multiplied by the benefit to the recipient, exceeds the reproductive cost to the actor. This is a prediction from the theory of kin selection formulated by W. D. Hamilton.
Harrison's rule states that parasite body sizes co-vary with those of their hosts. He proposed the rule for lice, but later authors have shown that it works equally well for many other groups of parasite including barnacles, nematodes, fleas, flies, mites, and ticks, and for the analogous case of small herbivores on large plants.
Hennig's progression rule states that when considering a group of species in cladistics, the species with the most primitive characters are found within the earliest part of the area, which will be the center of origin of that group. It is named for Willi Hennig, who devised the rule.
Jordan's rule states that there is an inverse relationship between water temperature and meristic characteristics such as the number of fin rays, vertebrae, or scale numbers, which are seen to increase with decreasing temperature. It is named after the father of American ichthyology, David Starr Jordan.
Kleiber's law states that the metabolic rate of animals and plants scales to 3/4ths the power of their mass. This is named for Max Kleiber, who observed it first in animals in 1932.
Lack's principle, proposed by David Lack, states that "the clutch size of each species of bird has been adapted by natural selection to correspond with the largest number of young for which the parents can, on average, provide enough food".
Rapoport's rule states that the latitudinal ranges of plants and animals are generally smaller at lower latitudes than at higher latitudes. It was named after Eduardo H. Rapoport by G. C. Stevens in 1989.
Rensch's rule states that, across animal species within a lineage, sexual size dimorphism increases with body size when the male is the larger sex, and decreases as body size increases when the female is the larger sex. The rule applies in primates, pinnipeds (seals), and even-toed ungulates (such as cattle and deer). It is named after Bernhard Rensch, who proposed it in 1950.
Schmalhausen's law, named after Ivan Schmalhausen, states that a population at the extreme limit of its tolerance in any one aspect is more vulnerable to small differences in any other aspect. Therefore, the variance of data is not simply noise interfering with the detection of so-called "main effects", but also an indicator of stressful conditions leading to greater vulnerability.
Thorson's rule states that benthic marine invertebrates at low latitudes tend to produce large numbers of eggs developing to pelagic (often planktotrophic [plankton-feeding]) and widely dispersing larvae, whereas at high latitudes such organisms tend to produce fewer and larger lecithotrophic (yolk-feeding) eggs and larger offspring, often by viviparity or ovoviviparity, which are often brooded. It was named after Gunnar Thorson by S. A. Mileikovsky in 1971.
Van Valen's law states that the probability of extinction for species and higher taxa (such as families and orders) is constant for each group over time; groups grow neither more resistant nor more vulnerable to extinction, however old their lineage is. It is named for the evolutionary biologist Leigh Van Valen.
von Baer's laws, discovered by Karl Ernst von Baer, state that embryos start from a common form and develop into increasingly specialised forms, so that the diversification of embryonic form mirrors the taxonomic and phylogenetic tree. Therefore, all animals in a phylum share a similar early embryo; animals in smaller taxa (classes, orders, families, genera, species) share later and later embryonic stages. This was in sharp contrast to the recapitulation theory of Johann Friedrich Meckel (and later of Ernst Haeckel), which claimed that embryos went through stages resembling adult organisms from successive stages of the scala naturae from supposedly lowest to highest levels of organisation.
Williston's law, first noticed by Samuel Wendell Williston, states that parts in an organism tend to become reduced in number and greatly specialized in function. He had studied the dentition of vertebrates, and noted that where ancient animals had mouths with differing kinds of teeth, modern carnivores had incisors and canines specialized for tearing and cutting flesh, while modern herbivores had large molars specialized for grinding tough plant materials.
See also
Aristotle's biology
References
Biogeography
Ecology | Biological rules | [
"Biology"
] | 2,089 | [
"Biological rules",
"Biogeography",
"Ecology",
"nan"
] |
50,550,040 | https://en.wikipedia.org/wiki/Carlitz%E2%80%93Wan%20conjecture | In mathematics, the Carlitz–Wan conjecture classifies the possible degrees of exceptional polynomials over a finite field Fq of q elements. A polynomial f(x) in Fq[x] of degree d is called exceptional over Fq if every irreducible factor (differing from x − y) or (f(x) − f(y))/(x − y)) over Fq becomes reducible over the algebraic closure of Fq. If q > d4, then f(x) is exceptional if and only if f(x) is a permutation polynomial over Fq.
The Carlitz–Wan conjecture states that there are no exceptional polynomials of degree d over Fq if gcd(d, q − 1) > 1.
In the special case that q is odd and d is even, this conjecture was proposed by Leonard Carlitz (1966) and proved by Fried, Guralnick, and Saxl (1993). The general form of the Carlitz–Wan conjecture was proposed by Daqing Wan (1993) and later proved by Hendrik Lenstra (1995)
References
Conjectures that have been proved
Polynomials | Carlitz–Wan conjecture | [
"Mathematics"
] | 237 | [
"Polynomials",
"Conjectures that have been proved",
"Mathematical problems",
"Mathematical theorems",
"Algebra"
] |
64,145,846 | https://en.wikipedia.org/wiki/Plant%20memory | In plant biology, plant memory describes the ability of a plant to retain information from experienced stimuli and respond at a later time. For example, some plants have been observed to raise their leaves synchronously with the rising of the sun. Other plants produce new leaves in the spring after overwintering. Many experiments have been conducted into a plant's capacity for memory, including sensory, short-term, and long-term. The most basic learning and memory functions in animals have been observed in some plant species, and it has been proposed that the development of these basic memory mechanisms may have developed in an early organismal ancestor.
Some plant species appear to have developed conserved ways to use functioning memory, and some species may have developed unique ways to use memory function depending on their environment and life history.
The use of the term plant memory still sparks controversy. Some researchers believe the function of memory only applies to organisms with a brain and others believe that comparing plant functions resembling memory to humans and other higher division organisms may be too direct of a comparison. Others argue that the function of the two are essentially the same and this comparison can serve as the basis for further understanding into how memory in plants works.
History
Experiments involving the curling of pea tendrils were some of the first to explore the concept of plant memory. Mark Jaffe recognized that pea plants coil around objects that act as support to help them grow. Jaffe’s experiments included testing different stimuli to induce coiling behavior. One such stimulus was the effect of light on the coiling mechanism. When Jaffe rubbed the tendrils in light, he witnessed the expected coiling response. When subjected to perturbation in darkness, the pea plants did not exhibit coiling behavior. Tendrils from the dark experiment were brought back into light hours later, exhibiting a coiling response without any further stimulus. The pea tendrils retained the stimulus that Jaffe had provided and responded to it at a later time. Proceeding these findings, the idea of plant memory sparked interest in the scientific community.
The Venus flytrap may suggest one possible mechanism for memory. Venus flytraps have many tiny hairs along the trap's surface that when touched, trigger the trap to close. But the process requires more than one hair to be touched. In the late 1980s, Dieter Hodick and Andrias Sievers proposed a model for memory retention in Venus flytraps involving calcium concentrations.
Comparing the phenomenon to human action potentials, they hypothesized that the first touch of a hair leads to an increase of calcium in the cell, allowing for a temporary retention of the stimulus. If a second stimulus does not occur shortly after the initial increase of calcium, then the calcium level will not surpass a certain threshold required to trigger the trap to shut, which they likened to a memory being lost. If a second stimulus occurs quickly enough, then the calcium levels can overcome the threshold and trigger the trap to close. This demonstrated a delayed response to an initial stimulus, which could be likened to short-term memory.
While further experiments supported short term retention of signals in some plant species, questions remained about long term retention.
In 2014, Monica Gagliano conducted experiments into long-term plant memory using Mimosa pudica, a plant unique for its ability to curl its leaves in defense against touching or shaking. In Gagliano’s experiment, the plants were repeatedly dropped from a prescribed height, shaking the branches and eliciting a defense response. Over time, Gagliano observed a decrease in leaf curling in response to being dropped. But when shaken by hand, the plants still curled their leaves. This appeared to show that the plants were still capable of the defense response, but that they remembered that the dropping stimulus didn’t pose a threat of herbivory.
Gagliano then tested to see how long the plant could retain the information for. She waited a month and then repeated the dropping experiment with the same individuals from the previous experiment. She observed that the plants had seemingly retained the memory of not needing a defense response when dropped. Gagliano's work suggested that some plant species may be capable of learning and retaining information over extended periods of time.
In 2016, Gagliano expanded on her work in plant memory with an experiment involving the common garden pea, Pisum sativum, which actively grows towards light sources. Gagliano established a Y-maze task with a light and a fan and placed each pea plant into the task. Gagliano observed that when young pea plants were grown in a Y-maze task where the light source came from the same direction as a fan, that when the pea plants were placed into a Y-maze task with only a fan, the pea plants grew in the direction of the fan. It appeared that the pea plants had learned to associate the fan with light. This seemingly contradicted the natural behavior of the pea plant to determine its directionality of growth based on light. Gagliano did note that this learned behavior was only successful when tested during the daytime. She suggested that the mechanism of learning may be regulated by metabolic demands and that associative learning may represent a derived trait of animals and plants from a common ancestor.
In 2020, Kasey Markel, a PhD student in plant biology at UC Davis attempted to recreate Gagliano’s experiment. Using a larger sample size and a fully blind analysis, he was unable to yield the same results. Markel cited the differing provider of the Pisum sativum seeds and brand of fan as possible variables that affected the outcome of her experiment. Markel did suggest that further verification of Gagliano’s work was necessary before Gagliano’s conclusions could be fully accepted.
Physiology
The physiology of plant memory is documented in many studies and is understood to have four main physiological mechanisms that work together in synchrony to provide the plant with basic memory functions, and are thought to be precursors to advanced memory functions found in animals. These four mechanisms are the storing and recalling, habituation, gene priming or epigenetics, and the biological clock.
Plant Memory due to Environmental Stimuli
The ability to respond to environmental stimuli is a skill that many plants possess. Exposure to mild stress is a good primer to plant memory. This memory that becomes developed from recurrent exposure better prepares a plant for future stressful factors. Plants also have a capacity for the amount of memory that they are able to possess and when they no longer are exposed to a certain factor they may “forget” what they learned to make room for new memories. Such stresses that plants remember and prime themselves for are drought, excessive light, oxidative stress, abscisic acid, and cold and warm climates.
Memories are formed in plants through metabolites or through transcription factors in the plant. Changes in gene expression due to methylation and/or paused RNA pol II may also play this role in memory formation. A similar phenomena as found in animal species. Though the mechanism of memory formation in plants is relatively unknown, it is hypothesized that a complex calcium signaling network is responsible for the formation and storage of a plant’s memories and past experiences. Free calcium responds to internal and external stimuli creating an electrochemical gradient through channels and pumps in the plant. This response is thought to be stored and ingrained within the plant for future recall to similarly stressful situations.
Storage and recall
The storage and recall method of memory occurs when a plant, in response to a stimuli, reduces or increases the concentration of a chemical in certain tissues, and maintains this concentration for a certain period of time. The plant then uses this concentration of chemical as a signal for a recall response. Stimuli known to create a store and recall responses like this are touch, damage, temperature, drought, and even electromagnetic radiation. It is suspected that Ca2+ signalling plays a key role in this form of plant memory. A proposed mechanism of this is that the presence or absence of Ca2+ acts as a long term on/off switch for cellular processes in response to stimuli for storing genes. Ca2+ along with electrical signalling, is also integral as a signalling pathway for plants to transmit signals of the original stimulus between cells or tissues throughout the plant. An example of short term electrical memory store and recall function can be seen in the trap mechanism of the Venus flytrap. When one hair on the trap is touched, an electrical is generated and retained for 20 seconds. The trap requires that at least one more hair is brushed within this 20 second period in order to reach the charge threshold required to close the trap. Electrical signaling from cell to cell in plants is controlled by proteins in the cell membrane. Protein memristors are biological resistor proteins that can depend on the electrical history of the cell, and are a class of protein that are shared between plants and animals in electrical memory function. There is also a neuroreceptor found in plants called glutamate, glutamate functions as a neurocommunicator of memory and learning in humans. In plants, glutamate functions as a signaling molecule that responds to multiple stressors such as salinity, temperature, drought conditions, pathogens, and wound stress. Experiments conducted showed expression and activation of glutamate receptors when subjected to stress.
Trauma Reaction Example:
Long-term trauma memory in plants has been an area of interest for several years because of its potential to understand other types of memory. In the mid-twentieth century, Rudolf Dostal and Michel Tellier conducted a set of experiments which revealed interesting results. Under normal conditions, the decapitation of the apical bud of a plant leads to symmetric growth of the lateral buds. However, Dostal and Thellier found that removing the cotyledon on one side of the plant, or simply wounding it, resulted in asymmetrical growth towards the healthier side of the plant. This trauma memory hypothesis was solidified when Thellier showed that past damage can be remembered by the plant even after removing both cotyledons, suggesting that trauma memory is stored in the bud. Dostal and Thellier were pioneers in understanding trauma memory in plants but the physiological and molecular processes involved are still unknown. In this article, we propose several potential mechanisms that could explain how information about past trauma is stored in the bud.
One proposed mechanism for plant memory storage in the bud is the relative rise in Ca2+ concentration within the cytosol of plant cells via calcium waves. The cytoplasm of plant cells has a relatively low concentration of Ca2+, but the cell has stores of Ca2+ throughout. These stores of Ca2+ are usually membrane bound organelles that have inositol-3-phosphate (IP3) dependent Ca2+ channels within their membranes. These channels only open when they are bound to IP3, a molecule that is produced through intracellular processes governed by the enzyme phospholipase C. Some of the Ca2+ channels are not IP3 dependent and open in response to other stimuli like electrical gradients or the stretching of a membrane. Once a Ca2+ channel (IP3 gated or not) opens, it can briefly stimulate the opening of adjacent channels. This allows for a wave of calcium to be released from these Ca2+ stores into the cytoplasm of the plant cell. Calcium will flow down its concentration gradient, from an area of high Ca2+ concentration to an area of low Ca2+ concentration, through the now open Ca2+ channels. Because (1) there are many forms of Ca2+ channels on these storage organelles (2) these channels respond to different stimuli and (3) depend on the relative concentration gradients of these stimuli, the kinetics and magnitude of calcium waves are specific to the stimuli that triggered them. The respective elevation in the concentration of Ca2+ in the cytoplasm “stores” the memory of the stimuli. This proposed mechanism is a form of plant memory storage.
Another potential mechanism involves electrical signals and calcium. When Ca2+ floods the cytoplasm it allows the plant to store a memory, the duration and amplitude of this Ca2+ wave is determined by the type of stimulus that was perceived and how the plant will store the memory. Electric signals are induced by variation potentials which are stimulated by an injury such as heat or a cut. There are also action potentials but these are stimulated by non-damaging stimuli such as temperature. The variation potential travels through the xylem and is regulated by both hydraulic pressure and system potentials, such as the Ca2+ flux. Two methods by which a signal may travel over a short distance is by propagating over the cell membrane through the plasmodesmata, or secondly the current of one cell membrane may depolarize a neighboring cell membrane without having to be in direct contact. But for memory purposes the electric signal needs to travel over a longer distance, sieve tubes are used since they have pores and a continuous plasma membrane which makes sieve tubes low resistance. With a trauma the xylem can have a change in hydrostatic pressure which leads to turgor changes in the neighboring parenchyma cells and then via mechano-sensors membrane potential changes. Sheath cells protect the signal when traveling from the mesophyll to the phloem which contains the sieve tubes. Although there are many suggested methods by which long-distance electric signals may travel, the exact ion channels that are used are still unknown, but recently GLR genes have been proposed to mediate wound stimulus through cation channels. Another possible method on storage memory and recall is the hormone auxin and how it reacts to a trauma.
While there are many hormones that dictate major plant processes and eventual changes in physiology, auxin remains the most prevalent hormone. Auxin serves to increase cell length, stimulated by light or gravity in processes known as phototropism and gravitropism, respectively. In terms of plant memory, Auxin may act as the mechanism as to which plants respond to stimuli previously encountered. Auxin moves to different sides of the cell, depending on the particular cell type and process initiated. In phototropism, auxin is transported to the side of the plant shaded. This is accomplished through the PIN transport proteins. PIN proteins act as a conduit for auxin, allowing auxin to flow between cells. As auxin accumulates on the shaded side of the plant, the hormone promotes cell elongation in the cells. Auxin does this by stimulating the expansibility of cell walls. This allows cells to expand and elongate, making the plant bend in one direction. This also occurs in the roots, under a different stimulus. Auxin also plays a role in regulating gene expression. The genes that are regulated are correlated with cell expansion biochemistry and physiology. In What a Plant Knows, David Chamovitz describes an experiment in which they test a plants long-term memory regarding past trauma. While the experiment (stated above) concluded that plants can store trauma memory, the exact mechanism is unknown. Chamovitz, along with the original perpetrators of the experiment Rudolf Dostal and Michel Tellier, postulate that Auxin may play a pivotal role in trauma memory because of the hormone's role in regulation of growth through multiple mechanisms including long term gene expression.
Trauma memory is a great example illustrating the physiology of memory storage and recall in plants. While the mechanisms responsible for it have yet to be determined, our current understanding of plant physiology allows us to propose three pathways to explore: Ca2+ flux, electrical signaling, and auxin stimulation. Long-term trauma memory is only one of the many distinct types of memory in plants and understanding its physiological and molecular mechanisms could reveal discoveries pertinent to other memory processes such as immune memory or musclemotor memory.
Habituation
The process of habituation in plants is very similar to the store and recall function, but lacks the recall action. In this case, information is stored and used to acclimate the plant to the original stimulus. A great example of this is research done on mimosa plants and their leaves' acclimated response to being dropped by Gagliano et al. In this study the plants initially reacted to being dropped by closing their leaves, but after the stimulus had been experienced a number of times the plants no longer responded to being dropped by closing their leaves.
Epigenetic memory
The third aspect of plant memory is epigenetics, where the plant, in response to a stimulus, undergoes histone and chromatin modification leading to changes in gene expression. These changes lead to a subsequent change in what proteins are made by the plant and establish a way for the plant to respond or be affected by stimuli from past experiences. These experiences can be passed down genetically from parent plant to offspring, giving an even longer-term memory of a stimulus such as a stressor or other environmental stimuli. It is important to note that these changes are different from genetic changes because they can be reversed in response to new stimuli or environmental conditions.
Biological clocks
Plants use biological clocks to perform certain actions at times they will be most effective. The two most well documented biological clocks in plants are the day and seasonal cycles which are usually established by photoreceptors. Once a plant has established a pattern of light, they can effectively memorize nighttime, daytime, or longer periods like seasons. A clear example of this can be seen in the ability of plants to over winter, cease leaf growth and then activate leaf growth in the spring when environmental conditions favor growth. Phytochrome, a receptor which is activated by red light and inactivated by far-red light, is one of the ways that plants use to control their flowering cycle.
These cycles, or circadian rhythms are controlled by genes associated with different spatial times that are activated when an environmental cue for that time is present. These genes control what proteins are made at certain times, as well as electrical and chemical signals that are produced to control motor proteins and other proteins. The overall result of these processes are subsequent changes in how the plant functions.
Summary
The combination of these four mechanisms of plant memory are proposed to work together to form different functions of memory in a plant. The overall proposed mechanism of this memory is a signal or environmental cues lead to a signal (chemical concentration, calcium waves, electrical, small RNAs, or phytohormones), and this eventually leads to the activation or deactivation of memory associated genes (store and recall, epigenetics, habituation, or circadian rhythms). The protein products of these genes then go on to produce actions based on the memory of the initial stimuli. Memory's molecular processes are not completely known, and several routes and interactions are thought to be involved, including these four aspects. However, more crucially, the systems outlined must be integrated in order to provide a complete knowledge of the memory process.
See also
Plant cognition
References
Plant intelligence
Memory | Plant memory | [
"Biology"
] | 3,882 | [
"Plant intelligence",
"Plants"
] |
64,145,959 | https://en.wikipedia.org/wiki/Christodoulos%20Floudas | Christodoulos Achilleus Floudas (August 31, 1959 – August 14, 2016) was a Greek–American chemical engineer.
Floudas completed a diploma in chemical engineering at the Aristotle University of Thessaloniki in 1982, and received his Ph.D. in 1986 at Carnegie Mellon University under the guidance of Ignacio Grossmann. Floudas began teaching at Princeton University upon earning his doctorate, and was later named the Stephen C. Macaleer ’63 Professor in Engineering and Applied Science. From February 2015, he was the director of the Energy Institute at Texas A&M University, as well as the Erle Nye ’59 Chair Professor for Engineering Excellence within the Artie McFerrin Department of Chemical Engineering.
His research areas were global optimization and process systems engineering. In 2011, Floudas was elected a member of the National Academy of Engineering "[f]or contributions to theory, methods, and applications of global optimization in process systems engineering, computational chemistry, and molecular biology." In 2013, he was elected a fellow of the Society for Industrial and Applied Mathematics. From 2014 to 2015, Floudas was listed as one of the highly cited researchers. His h-index is 100 according to Google Scholar.
Personal life
Floudas was born in Ioannina, Greece on 31 August 1959. He died on 14 August 2016 while on vacation in Chalkidiki, Greece at the age of 56.
References
1959 births
2016 deaths
Chemical engineering academics
21st-century American engineers
Members of the United States National Academy of Engineering
Scientists from Ioannina
American chemical engineers
Texas A&M University faculty
20th-century American engineers
Princeton University faculty
21st-century Greek educators
Greek engineers
20th-century Greek educators
Aristotle University of Thessaloniki alumni
Carnegie Mellon University alumni
Fellows of the Society for Industrial and Applied Mathematics | Christodoulos Floudas | [
"Chemistry"
] | 363 | [
"Chemical engineering academics",
"Chemical engineers"
] |
64,146,137 | https://en.wikipedia.org/wiki/Richard%20S.%20H.%20Mah | Richard S. H. Mah (16 December 1934 – 30 May 2004) was a Chinese-born chemical engineer and professor at Northwestern University in the United States.
Early life and education
Mah was born in Shanghai on 16 December 1934, to parents S. Fabian Soh Pai and E. Shang (Chang). Mah's parents sent him to England in 1950. Mah completed a Bachelor of Science in chemical engineering from the University of Birmingham, and received his Ph.D. in 1961 from the Imperial College London under the guidance of Roger W. H. Sargent on process systems engineering. Mah became the first Ph.D. graduate from the Sargent research group. Mah moved to the University of Minnesota in 1961 for his postdoctoral work. Mah married Stella Lee in 1962.
Career
Mah worked for Union Carbide between 1963 and 1967, then Esso. He joined the faculty of Northwestern University in 1972 as an associate professor, and retired in 1994 as a professor. Mah was a fellow of the American Institute of Chemical Engineers, and received its Computing in Chemical Engineering Award, Ernest Thiele Award, and other divisional awards. He was also awarded the American Society for Quality Jack Youden Prize.
Books
2 volumes
Death and legacy
Mah died on 30 May 2004 due to a heart attack at the age of 69 in Glenview, Illinois. From 2005, the department of chemical and biological engineering at Northwestern University held an annual Mah Memorial Lecture in his honor.
References
Chemical engineering academics
Chinese chemical engineers
20th-century Chinese engineers
Chinese expatriates in the United Kingdom
Engineers from Illinois
Fellows of the American Institute of Chemical Engineers
Chinese emigrants to the United States
1934 births
20th-century American engineers
Alumni of the University of Birmingham
Engineers from Shanghai
Alumni of Imperial College London
American chemical engineers
2004 deaths | Richard S. H. Mah | [
"Chemistry"
] | 368 | [
"Chemical engineering academics",
"Chemical engineers"
] |
64,146,235 | https://en.wikipedia.org/wiki/Computers%20%26%20Chemical%20Engineering | Computers & Chemical Engineering is an international, peer-reviewed scientific journal in the field of process systems engineering. The journal accepts general papers on process systems engineering, as well as emerging new areas and topics for new developments in the application of computing and systems technology to chemical engineering problems. The journal was founded in 1977 and is published 12 times a year. The journal's current Editor-in-Chief is Efstratios N. Pistikopoulos, and editors are J. H. Lee, A.B. Póvoa, and Fengqi You. Computers & Chemical Engineering offers authors two choices to publish their research: Gold Open Access and Subscription. Its impact factor is 4.000 in 2019.
References
Monthly journals
English-language journals
Academic journals established in 1977
Chemical engineering journals
Computer science journals | Computers & Chemical Engineering | [
"Chemistry",
"Engineering"
] | 163 | [
"Chemical engineering",
"Chemical engineering journals"
] |
64,147,531 | https://en.wikipedia.org/wiki/HD%20203030 | HD 203030, also known as V457 Vulpeculae, is a single, yellow-orange hued star with a sub-stellar companion in the northern constellation of Vulpecula. The designation HD 203030 is from the Henry Draper Catalogue, which is based on spectral classifications made between 1911 and 1915 by Annie Jump Cannon and her co-workers, and was published between 1918 and 1924. This star is invisible to the naked eye, having an apparent visual magnitude of 8.45. It is located at a distance of 128 light years from the Sun based on parallax, and is drifting closer with a radial velocity of −17 km/s.
The stellar classification of HD 203030 is K0V, indicating this is a K-type main-sequence star. It is likely very young, belonging to the 45 million years old IC 2391 open cluster. Based on photometric measurements by Hipparcos, it was found to exhibit low amplitude periodic variability with a range of 0.0139 in magnitude and a period of 4.14 days. However the General Catalog of Variable Stars lists its period as 6.664 days. It is now classified as a chromospherically active BY Draconis variable. The star has 97% of the mass of the Sun and 86% of the Sun's radius. It is radiating 59% of the luminosity of the Sun from its photosphere at an effective temperature of 5,603 K.
Planetary system
In 2006, direct imaging found co-moving companion at a projected separation of , suggesting this is a candidate brown dwarf of spectral class L7.5. It was shown to be in a bound orbit around the star by 2014. In 2017, a reanalysis indicated that the star HD 203030 is probably very young, and therefore both the primary and the observed companion are less massive than previously thought. This places the companion object at the planetary mass boundary. In 2019, the rotational period of HD 203030 B was measured as 7.5 hours, and a patchy cloud cover was detected.
References
K-type main-sequence stars
HD, 203030
Brown dwarfs
Planetary systems with one confirmed planet
Vulpecula
203030
105232
J10224361+5007420
Vulpeculae, V457
BY Draconis variables | HD 203030 | [
"Astronomy"
] | 486 | [
"Vulpecula",
"Constellations"
] |
64,148,345 | https://en.wikipedia.org/wiki/Aplax | Aplax is a dubious genus of extinct thalassochelydian turtle from the Late Jurassic of Germany. The type and only species is Aplax oberndorferi, named by Hermann von Meyer in 1843 for a complete juvenile skeleton from the early Tithonian of the Solnhofen Formation in Bavaria. Despite being aware that shell morphology changes during growth, Meyer named Aplax due to his consideration it represented a relative of Dermochelys, where the adults lack distinction of shell regions as in Aplax. However the taxon was later referred to Thalassochelydia by Anquetin and colleagues in 2017, and due to the loss of the original holotype it cannot be identified as a distinct taxon of a juvenile of existing Solnhofen turtles and is therefore a nomen dubium.
References
Thalassochelydia
Prehistoric turtle genera
Tithonian genera
Late Jurassic turtles
Late Jurassic reptiles of Europe
Jurassic Germany
Fossils of Germany
Nomina dubia
Fossil taxa described in 1843
Taxa named by Christian Erich Hermann von Meyer | Aplax | [
"Biology"
] | 213 | [
"Biological hypotheses",
"Nomina dubia",
"Controversial taxa"
] |
64,148,447 | https://en.wikipedia.org/wiki/PPE%20Portrait%20project | The PPE Portrait project started during the 2014–2015 Ebola outbreak in Liberia by artist Mary Beth Heffernan as a way to humanize physicians, nurses and other medical professionals wearing full personal protective equipment (PPE). Patients experiencing one of the most terrifying times of their lives are unable to see the faces of their medical staff, but having a photo sticker on the staff member's PPE gown allows the patient to better relate to their caregiver. This project was revived in 2020 by Stanford social scientist Cati Brown-Johnson and featured on The Rachel Maddow Show, NPR, Smithsonian magazine and KQED.
2014–2015 Ebola outbreak
The idea came from the 2014–2015 Ebola outbreak in Liberia. American artist Mary Beth Heffernan, who is a professor of art and art history at Occidental College, saw the full suits the Ebola health workers were wearing and she created the PPE Portrait Project. Heffernan called it "an art intervention designed to improve Ebola care". Regarding cultural sensitivity, Heffernan said that developing the project "involved close readings of Ebola survivors’ stories, in particular the first-person narratives of doctors who became infected and lived to write about it. Their stories were electrifying, and the words they chose to describe their experience—of being sick, isolated, and the trauma of not seeing a human face in their caregivers—are seared in my mind." The grant funded project focused on isolation of patients—the benefits of "puncturing that isolation" by allowing patients to better connect with their providers. Liberian doctors J. Soka Moses and Moses Massaquoi invited Heffernan to visit with the Ebola doctors and staff. Massaquoi said that he was receiving emails from people "pitching some untested scheme ... it was getting to be kind of a pain". But the proposal to put photos on the suits made so much sense he responded to Heffernan immediately. Heffernan told Maddow staff that she "had hoped the PPE portraits would become standard best medical practice for all kinds of patients who have to experience isolation of never seeing people outside of PPE—only masked faces for days at a time."
The Gold Foundation funded Heffernan to travel to Liberia. Heffernan had received $5,000 that she was using for this project. Health care staff there "reported feeling more human". She spent three weeks training the staff and left supplies for them to use. Heffernan wanted the project to be "sustainable and achievable with local means."
The project was featured in the Being Human exhibition at the Wellcome Collection in London in September 2019. The exhibit featured mannequins dressed in PPE with PPE Portrait labels. Heffernan provided first-person narratives from the healthcare workers featured to accompany the exhibit. Those featured received an honorarium for the use of their image and story.
In the five years since the Ebola outbreak, Heffernan approached many hospitals but found that they were uninterested. Medical staff wearing full PPE during the COVID-19 pandemic has changed that attitude with many hospitals. However, many of the providers involved in the original project have reported that they are not currently using PPE Portrait labels, as they are instead focused on the challenges of "sourcing and rigorously using the PPE itself."
COVID-19 pandemic
Cati Brown-Johnson from Stanford University School of Medicine revived the project for the COVID-19 pandemic. She says she is a social scientist who is interested in human connections. Brown-Johnson says the research behind this idea shows that "a warm and competent provider connects with the healing mechanisms within a person's own body. And PPE, obviously it's straight up and down ... competence. It tells you competence right away, the only warmth you might get would be a PPE portrait, that is some of the basis of the research that has us interested in pursuing this." Brown-Johnson further said that they are seeing an improvement in the morale of the medical staff, as it makes them feel more humanized. Brown-Johnson first tried out the revived program at a drive-thru testing site at Stanford.
Staff during one of the trial tests for the project said that right away they noticed better interactions with patients. One nurse, Anna Chico, who worked in the drive-up COVID-19 testing site, said she introduced herself by pointing to her portrait and saying "this is me under all this". Doctors reported that it felt like they were working with people on the team, "instead of inanimate objects".
The Rachel Maddow Show learned about this project when they noticed that doctor Ernest Patti from St. Barnabas Hospital, whom they had interviewed several times on the show about his experiences working with COVID-19 patients, appeared in full PPE but with a smiling photo of himself on the outside of his PPE gown. The Maddow staff inquired with Patti and learned that a woman had seen him on previous Maddow shows and mailed him a set of stickers of his own face for use on his gown. The woman was Dr. Lori Justice Shocket who is an artist and holds a medical degree. She is also married to an ER doctor and has a child and step-child who are also ER doctors. Shocket asks people to email her photos of their faces; she prints stickers and mails them back.
The goal of the project according to Heffernan is to give hospitals the tools and training so they can independently run the project. She hopes that all medical professionals will use PPE portraits whenever they wear masks irrespective of if they are in full PPE or not. In situations where medical staff are wearing a mask, seeing a smiling photo would be beneficial for the patient. Maddow further said of the PPE Portrait project that seeing a photo of their caregiver helps create a genuine connection instead of an "alien connection, even when they are doing the best to save your life". Smithsonian magazine states the feeling of seeing someone in full PPE is like "anonymizing these individuals as masked, expressionless staff members in space suits". In Liberia, Heffernan said that the medical workers "found themselves perceived as 'scary ninjas'—are isolating, dehumanizing and compound patient fear".
Other hospitals starting to use PPE portraits as of April 2020 are the University of Massachusetts Medical School, USC Keck School of Medicine and Boston Children's Hospital.
Practicalities
Stanford Medicine's website suggests that in high-risk settings the photo will be discarded with the disposal of the gown. In lower risk settings where the gown will be reused, the photo sticker will need to be disinfected before using the gown, much in the same way a name badge would be. Stanford suggests that if someone is creating the portrait of themself, they should use the portrait setting on their smartphone, look directly into the camera lens and "offer the smile you want your patients to see". Heffernan recommends using 8.5"×11" matte surface sticky labels that are not reusable. Laminating, disinfecting and reusing was first discussed but there were concerns that the hard edge of the plastic might damage the PPE gown and become a source for contamination. Medical staff can keep a supply of photo labels in the donning area. It is suggested that the photo be worn at "heart level, because your care is coming from your heart".
References
External links
Responses to the COVID-19 pandemic
Personal protective equipment
2014 in Liberia
Portrait photography
Vernacular photography | PPE Portrait project | [
"Engineering",
"Environmental_science"
] | 1,589 | [
"Safety engineering",
"Personal protective equipment",
"Environmental social science"
] |
64,148,468 | https://en.wikipedia.org/wiki/Euryaspis | Euryaspis is a dubious genus of extinct thalassochelydian turtle from the Late Jurassic of Germany. The type and only species is Euryaspis radians, originally proposed by Wagner in 1859 before being validly described and illustrated in 1861. The only specimen was a partial carapace probably from the Tithonian, although the original locality is unknown. The genus is referred to Thalassochelydia and has been considered a synonym of Eurysternum or Acichelys before, but casts that remain of the lost holotype show that it bears no features that can clarify its validity making it a nomen dubium.
References
Thalassochelydia
Prehistoric turtle genera
Tithonian genera
Late Jurassic turtles
Late Jurassic reptiles of Europe
Jurassic Germany
Fossils of Germany
Nomina dubia
Fossil taxa described in 1861 | Euryaspis | [
"Biology"
] | 171 | [
"Biological hypotheses",
"Nomina dubia",
"Controversial taxa"
] |
64,149,673 | https://en.wikipedia.org/wiki/6%CE%B1-Methylprogesterone | 6α-Methylprogesterone (6α-MP) is a progestin which was never marketed. It has 150% of the progestogenic potency of progesterone. In addition, and in contrast to progesterone, 6α-MP has weak androgenic, antiandrogenic, and synandrogenic actions. 6α-MP is structurally related to medroxyprogesterone acetate (MPA; 6α-methyl-17α-acetoxyprogesterone) and megestrol acetate (MGA; 6-dehydro-6-methyl-17α-acetoxyprogesterone), which possess androgenic and/or antiandrogenic activity to varying degrees similarly. MPA is more androgenic than 6α-MP and MGA.
References
Abandoned drugs
Anabolic–androgenic steroids
Diketones
Pregnanes
Progestogens | 6α-Methylprogesterone | [
"Chemistry"
] | 202 | [
"Drug safety",
"Abandoned drugs"
] |
64,150,594 | https://en.wikipedia.org/wiki/GCIRS%207 | GCIRS 7 is a red supergiant located in the Galactic Center. It is very bright and is one of the largest stars currently discovered, with a size about 1,170 solar radii. If placed in the Solar System, its photosphere would engulf the orbit of Jupiter.
See also
KW Sagittarii, another red supergiant in Sagittarius
VX Sagittarii, another red supergiant (or possible super-AGB star) in Sagittarius
References
Sagittarius (constellation)
Galactic Center
M-type supergiants
J17454004-2900225
TIC objects | GCIRS 7 | [
"Astronomy"
] | 136 | [
"Sagittarius (constellation)",
"Constellations"
] |
64,153,890 | https://en.wikipedia.org/wiki/Aminoacetaldehyde | Aminoacetaldehyde is the organic compound with the formula OHCCH2NH2. Under the usual laboratory conditions, it is unstable, tending instead to undergo self-condensation. Aminoacetaldehyde diethylacetal is a stable surrogate.
In nature, aminoacetaldehyde is produced by oxygenation of taurine catalyzed by taurine dioxygenase, which produces the sulfite H2NCH2CH(OH)SO3−.
See also
Aminoaldehydes and aminoketones
References
Amines
Aldehydes | Aminoacetaldehyde | [
"Chemistry"
] | 119 | [
"Amines",
"Bases (chemistry)",
"Functional groups"
] |
64,154,491 | https://en.wikipedia.org/wiki/Sooraj%20Surendran | Sooraj Surendran is an Indian technologist and electronic engineering graduate from Anna University. He has made significant contributions to motorized wheelchair deployment in Tamil Nadu.
Early life and education
Surendran was born in Kollam, Kerala, India. His mother Sudha was a housewife and his father was K Surendran Pillai.
He completed schooling in Sree Buddha, a Central Board of Secondary Education school in Karunagappalli, Kerala. He earned his degree from Anna University in electronic engineering.
Career
Surendran graduated from Anna University with a BTech in electronic engineering in 2011. He worked on motorized wheelchair design and nursing care bed electronic unit design, and developed an electronic system for nursing care beds that integrated Bluetooth technology to control the functions of a nursing care bed via an Android application. Surendran was invited to help develop electronic control units for lightweight motorized wheelchairs as a part of a Tamil Nadu program to distribute motorized wheelchairs to 2,000 people.
References
External links
Electronic engineering
1990 births
Living people
People from Kollam | Sooraj Surendran | [
"Technology",
"Engineering"
] | 214 | [
"Electrical engineering",
"Electronic engineering",
"Computer engineering"
] |
64,155,061 | https://en.wikipedia.org/wiki/8%20minutes%2046%20seconds | 8 minutes 46 seconds (8:46) is a symbol of police brutality that originated from the murder of George Floyd on May 25, 2020, in Minneapolis, Minnesota, United States. Derek Chauvin, a police officer, knelt on Floyd's neck, asphyxiating him. The duration that Chauvin spent kneeling was reported for weeks as 8 minutes 46 seconds, and later as 7 minutes 46 seconds, until body camera footage released in August 2020 showed that the actual time was 9 minutes 29 seconds. In the days following his murder, and the protests that followed, the duration became a focus of commemorations and debates, especially around Blackout Tuesday.
The duration has been specifically referenced in "die-in" protests in Minneapolis, New York, Boston, Detroit, Philadelphia, Pittsburgh, Portland, Chicago, Denver, and other cities, where protesters lay down for eight minutes and 46 seconds to protest police brutality and the racialized killings by law enforcement officers in the United States. It has also been used in numerous commemorations, vigils and gatherings to recognize Floyd and protest his murder, including at his memorial.
Calculation
The duration is how long Chauvin placed his knee on Floyd's neck, starting after Floyd was taken from his car and restrained by the Minneapolis Police Department; Floyd was lying unmoving on his stomach. The duration of 8:46 originated from the County Attorney of Hennepin County initial complaint against Chauvin. The time was based on a bystander's video of the incident, which began with Chauvin's knee already on Floyd's neck.
Weeks later, the prosecution reassessed the time to be 7 minutes and 46 seconds. Despite further questions about the exact time, the county attorney's office said prosecutors did not intend to revisit the timing matter, stating that it did not affect the case and more important matters existed. In August, police body camera footage was publicly released which showed that Chauvin had his knee on Floyd's neck for about 9:30.
In March 2021, the prosecution and defense teams both cited a more accurate duration of 9 minutes 29 seconds during Chauvin's trial (4:45 as Floyd cried out for help, 0:53 as Floyd flailed due to seizures, and 3:51 as Floyd was non-responsive).
Protests and commemorations
In addition to the die-ins that have used 8 minutes 46 seconds as their staged length, numerous marches and gatherings have used the duration to mark moments of silence, vigils, prayers, traffic slowdowns or taking a knee. George Floyd's memorial in Minneapolis on June 4, 2020, ended with mourners standing for 8:46 to commemorate Floyd. In March 2021, Floyd's family, attorneys and supporters knelt for 8:46 outside the courthouse prior to the opening arguments in Chauvin's trial.
Cities and institutions
In St. Petersburg, Florida, city officials announced that from June 2 to June 9, citizens should "join together in a silent and peaceful protest by standing outside on their front porch or yard for 8 minutes and 46 seconds" each night at 8:00 pm.
Following the example of New York City's Empire State Building, the Kennedy Center in Washington, D.C. has stated that it would go dark for nine nights to acknowledge the nearly nine minutes Floyd was held with a neck restraint.
On June 9, 2020, Minnesota Governor Tim Walz issued a proclamation declaring 8 minutes 46 seconds of silence at 11:00 a.m. CDT in memory of George Floyd, which coincided with the beginning of Floyd's funeral in Houston, Texas, that day.
On May 25, 2021, Minnesota Governor Tim Walz declared a statewide moment of silence for 9 minutes and 29 seconds, the actual length of time Chauvin knelt on Floyd, for 1:00 p.m. CDT to recognize the one-year mark since Floyd's murder.
Politics
Democratic senators observed 8 minutes 46 seconds of silence, with some kneeling, during their caucus meeting on June 4, 2020.
Corporations
The Google technology company held an eight-minute-and-46-second moment of silence for its employees on June 3, 2020, to honor black lives lost in relation to the murder of George Floyd.
The New York Stock Exchange and Nasdaq observed a moment of silence lasting 8 minutes and 46 seconds to coincide with Floyd's funeral in Houston, Texas. The exchanges' observations were covered and joined by CNBC. It was the longest moment of silence ever held in the NYSE's 228-year history.
On June 3, 2020, the Los Angeles Dodgers of Major League Baseball announced they would light up Dodger Stadium for eight minutes and forty-six seconds to honor George Floyd.
Media
In solidarity with a music industry campaign, #TheShowMustBePaused, major streaming services Spotify, Apple Music, Amazon Music, and YouTube Music all scheduled special related programming to pay tribute to the murder of Floyd.
ViacomCBS aired an eight-minute-46-second-long quasi-public service announcement on 11 of their television channels at 5 p.m. EST on June 1, 2020. At the same time, children's television channel Nickelodeon, another ViacomCBS property, stopped programming for 8:46 and displayed a message in "support of justice, equality, and human rights."
On June 12, 2020, Netflix released 8:46, a video of newly recorded stand-up by comedian Dave Chappelle, in which he primarily tackles the topic of Floyd. On the same day, Vice News uploaded an 8-minute-46-second-long YouTube video showcasing the protests.
See also
Memorials to George Floyd
References
External links
Murder of George Floyd
George Floyd protests
Durations | 8 minutes 46 seconds | [
"Physics"
] | 1,180 | [
"Temporal quantities",
"Physical quantities",
"Durations"
] |
64,155,180 | https://en.wikipedia.org/wiki/Chat%20fiction | Chat fiction is a format of web fiction written solely in the form of text-message or instant messaging conversations. Works are read primarily through dedicated mobile phone applications, the earliest being Hooked, which launched in 2015. The format became popular among teenagers and young adults, and other competing platforms followed, including Yarn and Tap, among others.
History
The first chat fiction platform, Hooked, was created by Prerna Gupta and Parag Chordia, who were writing a novel and decided to do A/B testing to gauge reader preferences. They found that most of their target audience of teenagers failed to finish 1,000-word excerpts of best-selling young-adult novels, but read through stories of the same length written as text message conversations. They accordingly developed and launched Hook in 2015. The app gained popularity from late 2016, and reached the Apple App Store's top position among free apps in 2017. Competing apps began launching the same year, including Yarn, which also has a focus on interactive fiction, and Tap, developed by the online publishing platform Wattpad.
Format
Chat fiction stories are presented as digital text conversations between two or more characters, without any narration. The format limits possible storytelling options, and presents a challenge to authors in conveying narrative only through dialogue. Most popular stories are of the horror and thriller genres. The format has been popular among teenagers and young adults, though it has been criticized as not providing a meaningful reading experience.
Applications usually present the story incrementally, with the user tapping to advance the story message by message. Some platforms feature content by paid writers, while others allow or rely on user contributions. Revenue is usually based on a freemium model, with basic access being free while subscribing offers removal of limits and other benefits.
References
Web fiction
Fiction forms
Interactive fiction
Interactive narrative
Instant messaging | Chat fiction | [
"Technology"
] | 368 | [
"Instant messaging"
] |
64,156,369 | https://en.wikipedia.org/wiki/Aminoacetaldehyde%20diethylacetal | Aminoacetaldehyde diethylacetal is the organic compound with the formula (EtO)2CHCH2NH2. A colorless liquid, it is used as a surrogate for aminoacetaldehyde.
See also
Aminoaldehydes and aminoketones
References
Amines
Acetals | Aminoacetaldehyde diethylacetal | [
"Chemistry"
] | 65 | [
"Acetals",
"Amines",
"Bases (chemistry)",
"Functional groups"
] |
64,156,671 | https://en.wikipedia.org/wiki/Jay%20H.%20Lee | Jay Hyung Lee (Korean: 이재형) is a professor at Department of Chemical and Biomolecular Engineering in KAIST (Korea Advanced Institute of Science and Technology). His h-index is 55 according to Google Scholar. Lee was a professor at Georgia Institute of Technology in the United States from 2000 to 2010. Lee is a fellow of Institute of Electrical and Electronics Engineers (IEEE). He is an editor of Computers & Chemical Engineering journal.
References
Year of birth missing (living people)
Living people
Academic staff of KAIST
South Korean engineers
Chemical engineers
Academic journal editors
Chemical engineering academics | Jay H. Lee | [
"Chemistry",
"Engineering"
] | 125 | [
"Chemical engineering academics",
"Chemical engineering",
"Chemical engineers"
] |
64,157,488 | https://en.wikipedia.org/wiki/ACS%20Sustainable%20Chemistry%20%26%20Engineering | ACS Sustainable Chemistry & Engineering is a weekly peer-reviewed scientific journal published by the American Chemical Society. It covers research in green chemistry, green engineering, biomass, alternative energy, and life cycle assessment. According to Journal Citation Reports, the journal has an impact factor of 7.1 in 2023. In 2023 Peter Licence (The University of Nottingham, UK) was appointed Editor-in-Chief.
Article types
The journal invites letters, articles, features, and perspectives (reviews) that address challenges of sustainability in the chemical enterprise and advance principles of green chemistry and green engineering.
References
Chemical engineering journals
Academic journals established in 2013
American Chemical Society academic journals
Biweekly journals
English-language journals | ACS Sustainable Chemistry & Engineering | [
"Chemistry",
"Engineering"
] | 141 | [
"Chemical engineering",
"Chemical engineering journals"
] |
64,158,374 | https://en.wikipedia.org/wiki/Ella%20Jones | Ella Jones (born 1955) is an American chromatographer, pastor, and politician who serves as the 12th mayor of Ferguson, Missouri. A former member of the Ferguson City Council, Jones is the first African-American and woman elected mayor of the city.
Education
Jones earned a Bachelor of Arts degree in chemistry from the University of Missouri–St. Louis.
Career
Prior to entering politics, Jones was a high-pressure liquid chromatographer. She worked at the Washington University School of Medicine and KV Pharmaceutical before becoming a sales director with Mary Kay. In April 2015, Jones was the first African-American elected to the Ferguson City Council, where she represented the city's first ward. In February 2020, Jones was selected to serve on the United States Environmental Protection Agency Local Government Advisory Committee.
In the 2017 municipal election, Jones ran for mayor, receiving 42.77% of the vote. It was the city's first election after the shooting of Michael Brown and subsequent Ferguson unrest.
In the June 2, 2020, mayoral election, Jones defeated fellow council member Heather Robinett. Jones succeeded incumbent James Knowles III, a Republican who was unable to seek re-election due to term limits. On June 17, 2020, Jones was sworn in as the first black and female mayor of Ferguson.
She is also a pastor in the African Methodist Episcopal Church.
Electoral history
Personal life
Jones moved to Ferguson, Missouri with her husband, Tim. Tim Jones died in 2013. Jones has one daughter.
References
External links
Ella Jones for Mayor campaign website
Ella Jones biography on the City of Ferguson, Missouri website
Missouri Democrats
University of Missouri–St. Louis alumni
African-American mayors in Missouri
21st-century mayors of places in Missouri
Women mayors of places in Missouri
Politicians from St. Louis County, Missouri
Chromatography
Living people
1955 births
Washington University in St. Louis staff | Ella Jones | [
"Chemistry"
] | 375 | [
"Chromatography",
"Separation processes"
] |
39,927,523 | https://en.wikipedia.org/wiki/SAFIR | SAFIR (or Single Aperture Far-InfraRed) is a proposed NASA space observatory for far-infrared light. The plan calls for a single large mirror in diameter, cryogenically cooled to . This would feed detector arrays sensitive from 5 to 1000 μm. The possibility of servicing such a telescope in space has been evaluated.
The design for SAFIR's primary mirror is large for a space-based telescope; for comparison, SAFIR's predecessor, the 2003 Spitzer Space Telescope, has a primary mirror only in diameter. SAFIR is oriented towards longer wavelengths so the mirror does not have to be as accurate compared to visible and near-infrared telescopes like the Hubble Space Telescope.
Mission
SAFIR will study the earliest phases of forming galaxies, stars, and planetary systems at wavelengths where these objects are brightest and which contain a wealth of unique information: from 20 micrometers to one millimeter. Most of this portion of the electromagnetic spectrum is not accessible from the ground because it is absorbed by moisture in Earth's atmosphere.
The combination of large mirror size and cold temperature would be designed to make SAFIR more than 1000 times more sensitive than Spitzer or even the Herschel Space Observatory; approaching the ultimate sensitivity limits at far-infrared and submillimeter wavelengths. SAFIR's sensitivity will be limited only by the irreducible noise of photons in the astrophysical background, rather than by infrared radiation from the telescope itself.
Observation
What makes this part of the spectrum so important is that, while far-infrared and submillimeter light can penetrate dust clouds, half or more of the optical and ultraviolet light produced in the universe is absorbed by dust and re-radiated in the far-infrared and submillimeter. Even in our local area of the universe, many galaxies are so dusty that they radiate mainly at those wavelengths.
This has two important consequences. First, to accurately measure the energy output and structure of objects that are obscured by dust, far-infrared continuum emission (emission across a broad band of wavelengths) must be included. Second, spectroscopy at these wavelengths makes the best probe of conditions in the vast clouds of dust and gases that lie between stars, known as the interstellar medium (ISM). These general features apply on all scales from the formation of stars and planetary systems in our corner of the Milky Way to the earliest galaxies that formed when the universe was only 10% to 20% of its current age.
Design
As a concept, wide ranges of technologies and architectures have been examined. The use of technology from the James Webb Space Telescope was also explored.
See also
Far-infrared astronomy
Infrared astronomy
List of proposed space observatories
Origins Space Telescope
SPICA
References
External links
SAFIR website at NASA.gov
Space telescopes
Proposed spacecraft
Infrared telescopes | SAFIR | [
"Astronomy"
] | 570 | [
"Space telescopes"
] |
39,928,510 | https://en.wikipedia.org/wiki/LinguaSys | LinguaSys, Inc. was a company headquartered in Boca Raton, Florida. LinguaSys provided multilingual human language software and services to financial, banking, hospitality, Customer Relations Management, technology, forensics and telecommunications blue chip enterprises, and the government and military.
History
LinguaSys was co-founded by chief executive officer Brian Garr in Boca Raton, Florida, USA; Chief Technology Officer Vadim Berman in Melbourne, Australia; and Vice President of Development and Architecture Can Unal in Darmstadt, Germany in 2010.
CEO Brian Garr was formerly CTO of Globalink from 1995 to 1998 and is a recipient of the Smithsonian Institution's "Heroes in Technology" award for his work in Machine Translation.
Billionaire Mark Cuban began investing in LinguaSys, Inc., in 2012.
Also in 2012, LinguaSys partnered with Salesforce.com, adding multilingual text analytics abilities to the company's social marketing services.
In 2014, LinguaSys made their technology available in a public cloud.
In 2015, LinguaSys added NLUI Server, which enables building Siri-like natural language applications rapidly in a variety of languages, to the products available in the public cloud.
In August 2015, LinguaSys was acquired by Aspect Software.
Products and services
LinguaSys uses interlingual natural language processing software to provide multilingual text, sentiment, relevance and conceptual understanding and analysis. LinguaSys trademarked its proprietary interlingual technology called Carabao Linguistic Virtual Machine. LinguaSys' multilingual software solutions are customized by clients and used via SaaS and behind the firewall. LinguaSys is an IBM Business Partner.
LinguaSys' multilingual technology is used on enterprise servers and consumer smartphones.
LinguaSys has developed an app TGPhoto which allows the user to snap a photo of some text and show a translation to one of fifty languages. The software works on Android, and Blackberry smartphones.
References
External links
2010 establishments in Florida
Companies based in Boca Raton, Florida
Language software
Software companies based in Florida
Technology companies established in 2010
Defunct software companies of the United States | LinguaSys | [
"Technology"
] | 450 | [
"Language software",
"Natural language and computing"
] |
39,928,780 | https://en.wikipedia.org/wiki/Tula%20virus | Tula virus (TULV), is a single-stranded, negative-sense RNA virus species of orthohantavirus first isolated from a European common vole (Microtus arvalis) found in Central Russia and primarily carried by rodents. It causes Hantavirus hemorrhagic fever with renal syndrome. The Microtus species are also found in North America, Europe, Scandinavia, Slovenia, Asia, and Western Russia. Human cases of Tula virus have also been reported in Switzerland and Germany.
References
External links
CDC's Hantavirus Technical Information Index page
Viralzone: Hantavirus
Virus Pathogen Database and Analysis Resource (ViPR): Bunyaviridae
Viral diseases
Hantaviridae
Hemorrhagic fevers
Rodent-carried diseases | Tula virus | [
"Biology"
] | 159 | [
"Virus stubs",
"Viruses"
] |
39,928,844 | https://en.wikipedia.org/wiki/Oblate%20spheroidal%20wave%20function | In applied mathematics, oblate spheroidal wave functions (like also prolate spheroidal wave functions and other related functions) are involved in the solution of the Helmholtz equation in oblate spheroidal coordinates. When solving this equation,
, by the method of separation of variables, , with:
the solution can be written as the product of a radial spheroidal wave function and an angular spheroidal wave function by . Here , with being the interfocal length of the elliptical cross section of the oblate spheroid.
The radial wave function satisfies the linear ordinary differential equation:
.
The angular wave function satisfies the differential equation:
.
It is the same differential equation as in the case of the radial wave function. However, the range of the radial coordinate is different from that of the angular coordinate .
The eigenvalue of this Sturm–Liouville problem is fixed by the requirement that be finite for .
For these two differential equations reduce to the equations satisfied by the associated Legendre polynomials. For , the angular spheroidal wave functions can be expanded as a series of Legendre functions. Such expansions have been considered by Müller.
The differential equations given above for the oblate radial and angular wave functions can be obtained from the corresponding equations for the prolate spheroidal wave functions by the substitution of for and for . The notation for the oblate spheroidal functions reflects this relationship.
There are different normalization schemes for spheroidal functions. A table of the different schemes can be found in Abramowitz and Stegun. Abramowitz and Stegun (and the present article) follow the notation of Flammer.
Originally, the spheroidal wave functions were introduced by C. Niven, which lead to a Helmholtz equation in spheroidal coordinates. Monographs tying together many aspects of the theory of spheroidal wave functions were written by Strutt, Stratton et al., Meixner and Schafke, and Flammer.
Flammer provided a thorough discussion of the calculation of the eigenvalues, angular wavefunctions, and radial wavefunctions for both the oblate and the prolate case. Computer programs for this purpose have been developed by many, including Van Buren et al., King and Van Buren, Baier et al., Zhang and Jin, and Thompson. Van Buren has recently developed new methods for calculating oblate spheroidal wave functions that extend the ability to obtain numerical values to extremely wide parameter ranges. These results are based on earlier work on prolate spheroidal wave functions. Fortran source code that combines the new results with traditional methods is available at http://www.mathieuandspheroidalwavefunctions.com.
Tables of numerical values of oblate spheroidal wave functions are given in Flammer, Hanish et al., and Van Buren et al.
Asymptotic expansions of angular oblate spheroidal wave functions for large values of have been derived by Müller., also similarly for prolate spheroidal wave functions.
The Digital Library of Mathematical Functions http://dlmf.nist.gov provided by NIST is an excellent resource for spheroidal wave functions.
References
External links
MathWorld Spheroidal Wave functions
MathWorld Prolate Spheroidal Wave Function
MathWorld Oblate Spheroidal Wave function
Special functions | Oblate spheroidal wave function | [
"Mathematics"
] | 725 | [
"Special functions",
"Combinatorics"
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39,932,121 | https://en.wikipedia.org/wiki/NCPEDP%20MphasiS%20Universal%20Design%20Awards | The NCPEDP-Mphasis Universal Design Awards are given every year on the eve of Independence Day of India to honour individuals and organisations doing exemplary work towards the cause of accessibility and thus ensuring a life of equality and dignity for persons with disabilities.
In order to spread awareness on Universal Design and to popularise this concept, National Centre for Promotion of Employment for Disabled People (NCPEDP), with the support of Mphasis, instituted these award in 2010.
Every year, these are given away in 3 categories: People with disabilities; Working Professionals' and Corporates or Organisations. For latest details about the Universal Design Awards please visit the NCPEDP website
NCPEDP-Mphasis Universal Design Awards, 2022
NCPEDP-Mphasis Universal Design Awards,2020
NCPEDP-Mphasis Universal Design Awards,2019
NCPEDP-Mphasis Universal Design Awards,2018
NCPEDP-Mphasis Universal Design Awards,2017
NCPEDP-Mphasis Universal Design Awards,2016
NCPEDP-Mphasis Universal Design Awards,2015
NCPEDP-Mphasis Universal Design Awards,2014
NCPEDP-Mphasis Universal Design Awards,2013
NCPEDP-Mphasis Universal Design Awards,2012
NCPEDP-Mphasis Universal Design Awards,2011
NCPEDP-Mphasis Universal Design Awards,2010
References
Design awards
Disability in India
Accessibility | NCPEDP MphasiS Universal Design Awards | [
"Engineering"
] | 287 | [
"Accessibility",
"Design",
"Design awards"
] |
39,932,177 | https://en.wikipedia.org/wiki/Shannon%20capacity%20of%20a%20graph | In graph theory, the Shannon capacity of a graph is a graph invariant defined from the number of independent sets of strong graph products. It is named after American mathematician Claude Shannon. It measures the Shannon capacity of a communications channel defined from the graph, and is upper bounded by the Lovász number, which can be computed in polynomial time. However, the computational complexity of the Shannon capacity itself remains unknown.
Graph models of communication channels
The Shannon capacity models the amount of information that can be transmitted across a noisy communication channel in which certain signal values can be confused with each other. In this application, the confusion graph or confusability graph describes the pairs of values that can be confused. For instance, suppose that a communications channel has five discrete signal values, any one of which can be transmitted in a single time step. These values may be modeled mathematically as the five numbers 0, 1, 2, 3, or 4 in modular arithmetic modulo 5. However, suppose that when a value is sent across the channel, the value that is received is (mod 5) where represents the noise on the channel and may be any real number in the open interval from −1 to 1. Thus, if the recipient receives a value such as 3.6, it is impossible to determine whether it was originally transmitted as a 3 or as a 4; the two values 3 and 4 can be confused with each other. This situation can be modeled by a graph, a cycle of length 5, in which the vertices correspond to the five values that can be transmitted and the edges of the graph represent values that can be confused with each other.
For this example, it is possible to choose two values that can be transmitted in each time step without ambiguity, for instance, the values 1 and 3. These values are far enough apart that they can't be confused with each other: when the recipient receives a value between 0 and 2, it can deduce that the value that was sent must have been 1, and when the recipient receives a value in between 2 and 4, it can deduce that the value that was sent must have been 3. In this way, in steps of communication, the sender can communicate up to different messages. Two is the maximum number of values that the recipient can distinguish from each other: every subset of three or more of the values 0, 1, 2, 3, 4 includes at least one pair that can be confused with each other. Even though the channel has five values that can be sent per time step, effectively only two of them can be used with this coding scheme.
However, more complicated coding schemes allow a greater amount of information to be sent across the same channel, by using codewords of length greater than one. For instance, suppose that in two consecutive steps the sender transmits one of the five code words "11", "23", "35", "54", or "42". (Here, the quotation marks indicate that these words should be interpreted as strings of symbols, not as decimal numbers.) Each pair of these code words includes at least one position where its values differ by two or more modulo 5; for instance, "11" and "23" differ by two in their second position, while "23" and "42" differ by two in their first position. Therefore, a recipient of one of these code words will always be able to determine unambiguously which one was sent: no two of these code words can be confused with each other. By using this method, in steps of communication, the sender can communicate up to messages, significantly more than the that could be transmitted with the simpler one-digit code. The effective number of values that can be transmitted per unit time step is .
In graph-theoretic terms, this means that the Shannon capacity of the 5-cycle is at least . As showed, this bound is tight: it is not possible to find a more complicated system of code words that allows even more different messages to be sent in the same amount of time, so the Shannon capacity of the 5-cycle is
Relation to independent sets
If a graph represents a set of symbols and the pairs of symbols that can be confused with each other, then a subset of symbols avoids all confusable pairs if and only if is an independent set in the graph, a subset of vertices that does not include both endpoints of any edge. The maximum possible size of a subset of the symbols that can all be distinguished from each other is the independence number of the graph, the size of its maximum independent set. For instance, ': the 5-cycle has independent sets of two vertices, but not larger.
For codewords of longer lengths, one can use independent sets in larger graphs to describe the sets of codewords that can be transmitted without confusion. For instance, for the same example of five symbols whose confusion graph is , there are 25 strings of length two that can be used in a length-2 coding scheme. These strings may be represented by the vertices of a graph with 25 vertices. In this graph, each vertex has eight neighbors, the eight strings that it can be confused with. A subset of length-two strings forms a code with no possible confusion if and only if it corresponds to an independent set of this graph. The set of code words {"11", "23", "35", "54", "42"} forms one of these independent sets, of maximum size.
If is a graph representing the signals and confusable pairs of a channel, then the graph representing the length-two codewords and their confusable pairs is , where the symbol represents the strong product of graphs. This is a graph that has a vertex for each pair of a vertex in the first argument of the product and a vertex in the second argument of the product. Two distinct pairs and are adjacent in the strong product if and only if and are identical or adjacent, and and are identical or adjacent. More generally, the codewords of length can be represented by the graph , the -fold strong product of with itself, and the maximum number of codewords of this length that can be transmitted without confusion is given by the independence number . The effective number of signals transmitted per unit time step is the th root of this number, .
Using these concepts, the Shannon capacity may be defined as
the limit (as becomes arbitrarily large) of the effective number of signals per time step of arbitrarily long confusion-free codes.
Computational complexity
The computational complexity of the Shannon capacity is unknown, and even the value of the Shannon capacity for certain small graphs such as (a cycle graph of seven vertices) remains unknown.
A natural approach to this problem would be to compute a finite number of powers of the given graph , find their independence numbers, and infer from these numbers some information about the limiting behavior of the sequence from which the Shannon capacity is defined. However (even ignoring the computational difficulty of computing the independence numbers of these graphs, an NP-hard problem) the unpredictable behavior of the sequence of independence numbers of powers of implies that this approach cannot be used to accurately approximate the Shannon capacity.
Upper bounds
In part because the Shannon capacity is difficult to compute, researchers have looked for other graph invariants that are easy to compute and that provide bounds on the Shannon capacity.
Lovász number
The Lovász number (G) is a different graph invariant, that can be computed numerically to high accuracy in polynomial time by an algorithm based on the ellipsoid method. The Shannon capacity of a graph G is bounded from below by α(G), and from above by (G). In some cases, (G) and the Shannon capacity coincide; for instance, for the graph of a pentagon, both are equal to . However, there exist other graphs for which the Shannon capacity and the Lovász number differ.
Haemers' bound
Haemers provided another upper bound on the Shannon capacity, which is sometimes better than Lovász bound:
where B is an n × n matrix over some field, such that bii ≠ 0 and bij = 0 if vertices i and j are not adjacent.
References
Graph invariants
Information theory | Shannon capacity of a graph | [
"Mathematics",
"Technology",
"Engineering"
] | 1,676 | [
"Telecommunications engineering",
"Applied mathematics",
"Graph theory",
"Graph invariants",
"Information theory",
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39,932,438 | https://en.wikipedia.org/wiki/SegReg | In statistics and data analysis, the application software SegReg is a free and user-friendly tool for linear segmented regression analysis to determine the breakpoint where the relation between the dependent variable and the independent variable changes abruptly.
Features
SegReg permits the introduction of one or two independent variables. When two variables are used, it first determines the relation between the dependent variable and the most influential independent variable, where after it finds the relation between the residuals and the second independent variable. Residuals are the deviations of observed values of the dependent variable from the values obtained by segmented regression on the first independent variable.
The breakpoint is found numerically by adopting a series tentative breakpoints and performing a linear regression at both sides of them. The tentative breakpoint that provides the largest coefficient of determination (as a parameter for the fit of the regression lines to the observed data values) is selected as the true breakpoint. To assure that the lines at both sides of the breakpoint intersect each other exactly at the breakpoint, SegReg employs two methods and selects the method giving the best fit.
SegReg recognizes many types of relations and selects the ultimate type on the basis of statistical criteria like the significance of the regression coefficients. The SegReg output provides statistical confidence belts of the regression lines and a confidence block for the breakpoint. The confidence level can be selected as 90%, 95% and 98% of certainty.
To complete the confidence statements, SegReg provides an analysis of variance and an Anova table.
During the input phase, the user can indicate a preference for or an exclusion of a certain type. The preference for a certain type is only accepted when it is statistically significant, even when the significance of another type is higher.
ILRI provides examples of application to magnitudes like crop yield, watertable depth, and soil salinity.
A list of publications in which SegReg is used can be consulted.
Equations
When only one independent variable is present, the results may look like:
X < BP ==> Y = A1.X + B1 + RY
X > BP ==> Y = A2.X + B2 + RY
where BP is the breakpoint, Y is the dependent variable, X the independent variable, A the regression coefficient, B the regression constant, and RY the residual of Y.
When two independent variables are present, the results may look like:
X < BPX ==> Y = A1.X + B1 + RY
X > BPX ==> Y = A2.X + B2 + RY
Z < BPZ ==> RY = C1.Z + D1
Z > BPZ ==> RY = C2.Z + D2
where, additionally, BPX is BP of X, BPZ is BP of Z, Z is the second independent variable, C is the regression coefficient, and D the regression constant for the regression of RY on Z.
Substituting the expressions of RY in the second set of equations into the first set yields:
X < BPX and Z < BPZ ==> Y = A1.X + C1.Z + E1
X < BPX and Z > BPZ ==> Y = A1.X + C2.Z + E2
X > BPX and Z < BPZ ==> Y = A2.X + C1.Z + E3
X > BPX and Z > BPZ ==> Y = A2.X + C2.Z + E4
where E1 = B1+D1, E2 = B1+D2, E3 = B2+D1, and E4 = B2+D2 .
Alternative
As an alternative to regressions at both sides of the breakpoint (threshold), the method of partial regression can be used to find the longest possible horizontal stretch with insignificant regression coefficient, outside of which there is a definite slope with a significant regression coefficient. The alternative method can be used for segmented regressions of Type 3 and Type 4 when it is the intention to detect a tolerance level of the dependent variable for varying quantities of the independent, explanatory, variable (also called predictor).
The attached figure concerns the same data as shown in the blue graph in the infobox at the top of this page. Here, the wheat crop has a tolerance for soil salinity up to the level of EC=7.1 dS/m instead of 4.6 in the blue figure. However, the fit of the data beyond the threshold is not as well as in the blue figure that has been made using the principle of minimization of the sum of squares of deviations of the observed values from the regression lines over the whole domain of explanatory variable X (i.e. maximization of the coefficient of determination), while the partial regression is designed only to find the point where the horizontal trend changes into a sloping trend.
See also
Segmented regression
References
Statistical software
Pascal (programming language) software | SegReg | [
"Mathematics"
] | 1,014 | [
"Statistical software",
"Mathematical software"
] |
39,933,282 | https://en.wikipedia.org/wiki/Sublimation%20sandwich%20method | The sublimation sandwich method (also called the sublimation sandwich process and the sublimation sandwich technique) is a kind of physical vapor deposition used for creating man-made crystals. Silicon carbide is the most common crystal grown this way, though other crystals may also be created with it (notably gallium nitride).
In this method, the environment around a single crystal or a polycrystalline plate is filled with vapor heated to between 1600°C and 2100°C. Changes to this environment can affect the gas phase stoichiometry. The source-to-crystal distance is kept very low, between 0.02mm to 0.03mm. Parameters that can affect crystal growth include source-to-substrate distance, temperature gradient, and the presence of tantalum for gathering excess carbon. High growth rates are the result of small source-to-seed distances combined with a large heat flux onto a small amount of source material with no more than a moderate temperature difference between the substrate and the source (0.5-10°C). The growth of large boules, however, remains quite difficult using this method, and it is better suited to the creation of epitaxial films with uniform polytype structures. Ultimately, samples with a thickness of up to 500 μm can be produced using this method.
References
See also
Lely method
Czochralski process
Mokhov, E. et al.: “Growth of Silicon Carbide Bulk Crystals by the Sublimation Sandwich Method”, Elsevier Science S.A., 1997, pp. 317-323
Crystallography
Materials science
Thin film deposition | Sublimation sandwich method | [
"Physics",
"Chemistry",
"Materials_science",
"Mathematics",
"Engineering"
] | 340 | [
"Applied and interdisciplinary physics",
"Thin film deposition",
"Coatings",
"Thin films",
"Materials science",
"Crystallography",
"Condensed matter physics",
"nan",
"Planes (geometry)",
"Solid state engineering"
] |
39,933,524 | https://en.wikipedia.org/wiki/Female%20cosmetic%20coalitions | The theory of female cosmetic coalitions (FCC) represents a controversial attempt to explain the evolutionary emergence of art, ritual and symbolic culture in Homo sapiens. The theory was proposed by evolutionary anthropologists Chris Knight and Camilla Power together with archaeologist Ian Watts.
Supporters of this theory contest the prevailing assumption that the earliest art was painted or engraved on external surfaces such as cave walls or rock faces. They argue instead that art is much older than previously thought and that the canvas was initially the human body. The earliest art, according to FCC, consisted of predominantly blood-red designs produced on the body for purposes of cosmetic display and resistance to unwanted sex.
Female cosmetic coalitions as a conceptual approach links:
Darwin's theory of evolution by natural and sexual selection
research into sexual signalling by wild-living monkeys and apes
the fossil record of encephalization in human evolution
recent archaeological discoveries of red-ochre pigments dating back to the speciation in Africa of Homo sapiens around 250,000 years ago
modern hunter-gatherer ethnography
These seemingly divergent topics come together in a co-authored publication attempting to explain why the world today is populated by modern Homo sapiens instead of by the equally large-brained, previously successful Neanderthals. An article published in the journal Current Anthropology in 2016 gives an account of exhaustive archaeological testing of the FCC theory, including robust debate between specialists.
Details of the FCC model
Reproductive synchrony
In primates, reproductive synchrony usually takes the form of conception and birth seasonality. The regulatory 'clock', in this case, is the sun's position in relation to the tilt of the earth. In nocturnal or partly nocturnal primates—for example, owl monkeys— the periodicity of the moon may also come into play. Synchrony in general is for primates an important variable determining the extent of 'paternity skew'—defined as the extent to which fertile matings can be monopolised by a fraction of the population of males. The greater the precision of female reproductive synchrony—the greater the number of ovulating females who must be guarded simultaneously—the harder it is for any dominant male to succeed in monopolising a harem all to himself. This is simply because, by attending to any one fertile female, the male unavoidably leaves the others at liberty to mate with his rivals. The outcome is to distribute paternity more widely across the total male population, reducing paternity skew (figures a, b).
Concealed ovulation, synchrony and evolution
Reproductive synchrony can never be perfect. On the other hand, theoretical models predict that group-living species will tend to synchronise wherever females can benefit by maximising the number of males offered chances of paternity, minimising reproductive skew. The same models predict that female primates, including evolving humans, will tend to synchronise wherever fitness benefits can be gained by securing access to multiple males. Conversely, group-living females who need to restrict paternity to a single dominant harem-holder should assist him by avoiding synchrony.
In the human case, according to FCC, evolving females with increasingly heavy childcare burdens would have done best by resisting attempts at harem-holding by locally dominant males. No human female needs a partner who will get her pregnant only to disappear, abandoning her in favour of his next sexual partner. To any local group of females, the more such philandering can be successfully resisted—and the greater the proportion of previously excluded males who can be included in the breeding system and persuaded to invest effort—the better. By evolving concealed ovulation and continuous receptivity, females force males into longer periods of consortship if they are to have a good chance of achieving impregnation (figures c,d). Reproductive synchrony—whether seasonal, lunar or a combination of the two—is a key strategy for reproductive levelling, reducing paternity skew and involving more males in investment in offspring. Greater reproductive synchrony owing to seasonality during glacial cycles may have differentiated Neanderthal reproductive strategies from those of Homo sapiens ancestors.
Costs of increasing brain-size
In this model, the factor driving female strategies is the high cost to females of increasingly large-brained offspring, requiring increased investment from males. As females of Homo heidelbergensis, the ancestor of Neanderthals and modern humans, came under increasing selection pressure for larger brain size within the past half million years, they needed more energy in support. This meant greater productivity by males as hunters. However, in the Darwinian world of primate sexual competition, males may be more interested in finding new fertile females than in supplying the needs of breast-feeding mothers and their infants. Women, unlike chimpanzees, do not show their fertile time. But females cannot easily disguise menstruation. Menstrual periods mark out very clearly which females are coming close to fertility among other females who are pregnant and lactating. Dominant males could therefore target the cycling females and neglect those most in need of support.
Menstruation, synchrony and cosmetics
FCC proponents argue that menstruation became a key problem because it potentially creates conflicts between the females and conflicts between males. Menstruation has little social impact among chimpanzees or bonobos, since visible oestrus swellings are the focus of male attention. But once external signs of ovulation had been phased out in the human lineage, according to FCC, menstruation became salient as the one remaining external promise of fertility. Potentially, dominant males might exploit such information, repeatedly targeting newly cycling females at the expense of pregnant or nursing mothers (figure e). Those who might lose male investment needed to take control. According to FCC, older and more experienced females did this by initiating newly cycling females into their kin-based coalitions (figures f, g). Red ochre pigments allowed women to take conscious control over their signals, resisting any dominant male strategy of picking and choosing between them on biological grounds. It is argued that because precise, sustained menstrual synchrony is difficult to achieve, painting up with blood-red pigments was the next best thing, enabling the benefits of artificial, ritually constructed synchrony.
Effect on male strategies
To explore a male strategic point of view, proponents of FCC make a simple model of alternative strategies. Female A uses cosmetics as part of her ritual coalition whenever one of them menstruates; Female B and all her female neighbors use no cosmetics. Male A is prepared to work/invest to gain access; Male B tries a philanderer strategy, moving to the next cycling fertile female, neglecting the previous partner once she is pregnant. Very quickly, Male A will end up working/doing bride-service for Female A's coalition, since he has no competition from Male B. Male A gains regular fitness as a result. Male B will pair up with Female B, but is then liable to abandon her if he finds a new cycling female. She then has little support during pregnancy/breastfeeding. The question will be whether Male B gains sufficient fitness via a roving strategy of picking up cycling, non-cosmetic females. If Male A is not able to compete with Male B in terms of dominance, he is better off choosing the cosmetic females. Because Female B and her non-cosmetic female neighbors get the attentions, but no reliable investment, from Male B, they discourage any investment from the likes of Male A. Once costs of encephalization begin to bite and cooperative strategies are needed to support offspring, how many females will be choosing philanderers in preference to investors? Those females are not likely to be ancestors of large-brained hominins like ourselves or the Neanderthals.
Reverse dominance, sacredness and taboo
Female strategies of counter-dominance culminated, according to this body of theory, in the eventual overthrow of primate-style dominance and its replacement by hunter-gatherer-style 'reverse dominance'. 'Reverse dominance' is defined by evolutionary anthropologists as an inverted social hierarchy—rule from below by an ungovernable community, leading to an egalitarian — in some cases gender-egalitarian — social order.
The FCC model predicts the specific form of reverse dominance display needed by female coalitions resisting would-be dominant or philanderer males. Females needed to signal 'No' by constructing themselves as inviolable using red ocher pigments. To assert ritual power, they needed to go periodically on 'sex strike'. To defend themselves physically against harassment by non-kin males, defiant females needed to draw on the support of male kin—sons and brothers—as members of their reverse dominance coalitions. In order to reverse signals of sexual availability, it was logical to sing and dance an unmistakable message: 'Wrong species, wrong sex, wrong time!'. On this basis, FCC theory leads us to expect 'divine' or 'totemic' spiritual entities depicted in early rock art to be therianthropic ('wrong species'), sex-ambivalent ('wrong sex') and blood-red ('wrong time') (figure h).
This brings FCC into line with Ḗmile Durkheim, who argued that the earliest divine beings were ritually generated representations of society. Durkheim's 'society', according to FCC, was in the first instance the bottom-up authority of Female Cosmetic Coalitions.
Interpreting the ochre record
It was once thought that art and symbolic culture first emerged in Europe some 40,000 years ago, during the Middle-to-Upper Palaeolithic transition – often termed the 'symbolic explosion' or 'Upper Palaeolithic revolution'. Some archaeologists still adhere to this view. Others now accept that symbolic culture probably emerged in sub-Saharan Africa at a much earlier date, during the period known as the Middle Stone Age. The evidence consists of traditions of ground ochre with strong selection for the colour red, examples of so-called ochre 'crayons' which appear to have been used for purposes of design, probably on the body, and geometric engravings on blocks of ochre. All this apparently formed part of a cosmetics industry dated to between 100,000 and 200,000 years ago. In addition, from about 100,000 years ago, we have pierced shells which appear to show signs of wear, suggesting that they were strung together to make necklaces. If the ochre tradition has been correctly interpreted, it constitutes evidence for the world's first 'art'—an aspect of 'symbolic culture'—in the form of personal ornamentation and body-painting. An alternative viewpoint is that pigment-only decorative systems are merely individualistic display, not necessarily indicative of ritual, whereas the bead traditions testify to language, institutionalized relationships and full-scale ritual and symbolic culture.
The most thorough recent survey of the African Middle Stone Age (MSA) ochre record is presented by Rimtautas Dapschauskas and colleagues. In a meta-analysis of 100 African sites, they ask when and where habitual ochre use emerged and the significance this had for the development of ritual behavior. They directly address the Female Cosmetic Coalitions hypothesis and test its predictions. They identify three continent-wide distinct phases of ochre use: an initial phase (500-330 thousand years ago); an emergent phase (330-160 ka); and an habitual phase from 160 ka, when a third of sites from South to East Africa and up to North Africa contain red ochre. In agreement with the FCC model, the authors regard 'habitual ochre use as a proxy for the emergence of regular collective rituals'. They view 'a large proportion of ochre finds from the MSA as the material remains of past ritual activity'. This builds cogently on the position taken by the FCC team three decades ago – that the ochre marked ritual activity critical to the emergence of symbolic cognition.
Implications for the origins of language
Proponents of this model claim that it helps to explain when and how language in our species emerged. Among 'Machiavellian', competitive nonhuman primates, sex is a major source of conflict, mutual suspicion and mistrust, as a result of which group members attempt to minimise the cost of deception by responding only to bodily signals which are intrinsically 'hard to fake'. This social pressure from receivers prevents language from even beginning to emerge. FCC theorists argue that for signals as cheap and intrinsically unreliable as words to become socially accepted, unprecedentedly intense levels of in-group trust were required. An effect of the Female Cosmetic Coalitions strategy, claim its supporters, was to minimise internal sexual conflict within each gender group, giving rise to a trusting social atmosphere such as is found among extant human egalitarian hunter-gatherers. These new levels of public trust, according to supporters of the model, enabled our species' latent linguistic capacities to flourish where previously they had been suppressed.
{{quotation|Too many candidate theories are either too vague, or make predictions that fall outside the available evidence. In contrast, a good example in this regard is the Female Cosmetic Coalitions Model, which does provide specific testable predictions.|{{Citation|title= Johansson, S. 2014. How can a social theory of language evolution be grounded in evidence? In D. Dor, C. Knight and J. Lewis (eds), The Social Origins of Language. Oxford: Oxford University Press, pp. 64-56}}|}}
Testable predictions of the model
Its supporters claim that FCC is the only Darwinian theory to explain why there is so much red ochre in the early archaeological record of modern humans and why modern humans are then associated with red ochre wherever they went as they emerged from Africa. It is claimed that, more than any other theoretical model of modern human origins, FCC offers detailed and specific predictions testable in the light of data from a wide variety of disciplines.
Archaeology
Earliest evidence of symbolic behaviour should be found in a cosmetics industry focused on blood-red pigments.
Palaeontology
The time-window should fit with fossil evidence for encephalization rates. On this basis, the earliest onset of the strategy should neither pre-date c. 600,000 B.P. nor post-date c. 150,000 B.P., by which time modern levels of cranial capacity had evolved.
Kinship and male investment
Matrilocal residence with bride service is expected as the initial situation.
Ethnography of magico-religious symbolism
Counter-dominance should generate collective counter-reality. The first gods are therefore expected to be represented as WRONG + RED (wrong species/sex/time).
Hunters' prohibitions on sex and menstruation are expected to operate within a lunar/menstrual cosmology.
Results
Proponents of FCC argue that the main predictions which can be derived from their model should be easy, in principle, to falsify.
In their recent survey of the MSA ochre record, Dapschauskas and colleagues confirm FCC's prediction that no ochre should be found in Acheulean levels (i.e. before 600,000 B.P.). While these authors identify three phases of the ochre record – initial, emergent and habitual – the FCC team always argued for two basic stages, firstly an ad hoc stage with improvisatory use of cosmetics and then, driven by increased brain size, a second stage in which ocher use became regular and habitual while underpinning a symbolically structured sexual division of labour. Despite this divergence in terminology, both teams agree on the critical point that humans began using ocher regularly and habitually for ritual purposes from around 160,000 years ago. As Dapschauskas and colleagues acknowledge, Knight, Power and Watts predicted this date on theoretical grounds thirty years earlier, when much less was known about the ocher record. In an article published in 1995, the FCC team focused on the intersection of increasing brain size (putting extra energetic demands on mothers) with the cold, dry Marine Isotope Stage 6 (MIS6), when people would have experienced severe energy pinch points during lean, dry seasons. Knight, Power and Watts argued: 'Reproductive stress motoring "sham menstruation" may have become most acute in the period 160-140 Kya, the height of the Penultimate Glacial Cycle.'
FCC theory is currently being debated, having received significant media coverage. Despite this, not all scholars agree and the model remains controversial.
See also
Body art
Body painting
Cosmetics
Human evolution
The Human Revolution (human origins)
Origins of society
Sex strike
Symbolic culture
Prehistoric art
Ochre
Reproductive synchrony
Menstrual synchrony
Blood Relations: Menstruation and the origins of culture
References
External links
Knight, C. 1991. 'The Sex Strike'. Chapter 4 in Blood Relations. Menstruation and the origins of culture.'' New Haven and London: Yale University Press, pp. 122–153.
Paleoanthropology
History of cosmetics
Prehistoric art
Sexual selection | Female cosmetic coalitions | [
"Biology"
] | 3,526 | [
"Evolutionary processes",
"Behavior",
"Sexual selection",
"Mating"
] |
39,934,192 | https://en.wikipedia.org/wiki/The%20Demon%20Under%20the%20Microscope | The Demon Under the Microscope: From Battlefield Hospitals to Nazi Labs, One Doctor's Heroic Search for the World's First Miracle Drug is a 2006 nonfiction book about the discovery of Prontosil, the first commercially available antibacterial antibiotic and sulfanilamide, the second commercial antibiotic. Prontosil was the first commercially available antibacterial antibiotic (with a relatively broad effect against Gram-positive cocci. It was developed in the 1930s by a research team at the Bayer Laboratories of the IG Farben conglomerate in Germany. The discovery and development of this first sulfonamide drug opened a new era in medicine.
Overview
The book's form is narrative nonfiction, in which history is written with the color and drama of a novel. The major plot follows the life of German physician Gerhard Domagk, from his medical service in World War I through the discovery of Prontosil for the Bayer company in the 1920s, and his subsequent jailing by Nazi authorities for the crime of accepting a Nobel Prize in 1939.
In addition to Domagk's work, the book focuses on the competition between German and French researchers—notably those in the laboratory of Ernest Fourneau at the Pasteur Institute in Paris—both for income and credit for work with the groundbreaking family of new drugs. Finally, the book describes the dramatic impact of these first antibiotics on medicine and culture, through stories on their use (while still experimental) in saving the life of the son of President Franklin D. Roosevelt; their tie to a tragic mass poisoning in the 1930s; and the subsequent passage of legislation that set up the modern Food and Drug Administration (FDA), creating the blueprint for today's medicinal drug laws.
Reception
Critical reception for the book was positive. In a starred review, Kirkus Reviews said Hager "does a remarkable job of transforming material fit for a biology graduate seminar into highly entertaining reading." The Wall Street Journal, in its review, noted "This is a grand story, and Mr. Hager tells it well, describing the birth of a new era in medicine -- soon to include penicillin and streptomycin -- and the difference it made to mankind. One can easily imagine The Demon Under the Microscope, like Microbe Hunters before it, inspiring in young, idealistic readers the enthusiasm for medical research and the zeal for healing that generates great physicians."
References
2006 non-fiction books
History books about medicine
Antibiotics | The Demon Under the Microscope | [
"Biology"
] | 503 | [
"Antibiotics",
"Biocides",
"Biotechnology products"
] |
39,935,332 | https://en.wikipedia.org/wiki/Methanizer | Methanizer is an appliance used in gas chromatography (GC), which allows the user to detect very low concentrations of carbon monoxide and carbon dioxide. It consists of a flame ionization detector, preceded by a hydrogenating reactor, which converts CO2 and CO into methane CH4. Methanizers contain a hydrogenation catalyst to achieve this conversion. Nickel is commonly used as the catalyst and there are alternatives available.
Chemistry
On-line catalytic reduction of carbon monoxide to methane for detection by FID was described by Porter & Volman, who suggested that both carbon dioxide and carbon monoxide could also be converted to methane with the same nickel catalyst. This was confirmed by Johns & Thompson, who determined optimum operating parameters for each of the gases.
CO2 + 2H2 ↔ CH4 + O2
2CO + 4H2 ↔ 2CH4 + O2
Typical design
The catalyst traditionally consists of a 2% coating of Ni in the form of nickel nitrate deposited on a chromatographic packing material (e.g. Chromosorb G).
A 1½" long bed is packed around the bend of an 8"×1/8" SS U-tube. The tube is clamped in a block so that the ends protrude down into the column oven for connection between column or TCD outlet and FID base. Heat is provided by a pair of cartridge heaters and controlled by a temperature controller.
Hydrogen for the reduction can be provided either by adding it via a tee at the inlet to the catalyst (preferred), or by using hydrogen as carrier gas.
Start-up
If the raw catalyst is supplied in the form of nickel oxide, it is necessary to reduce it to metallic nickel before it will operate properly. Alternative catalysts do not necessarily need a reduction treatment. Methanizers should not be heated without hydrogen being supplied to them.
Operating characteristics
Temperature
Conversion of both CO and CO2 to CH4 starts at a catalyst temperature below 300°C, but the conversion is incomplete and peak tailing is evident. At around 340°C, conversion is complete, as indicated by area measurements, but some tailing limits the peak height. At 360-380°C, tailing is eliminated and there is little change in peak height up to 400°C. Operating temperatures for various methanizers range from 350-400°C.
Although carbonization of CO has been reported at temperatures above 350°, it is rather a rare phenomenon.
Range
The conversion efficiency is essentially 100% from minimum detectable levels up to a flow of CO or CO2 at the detector of about g/s. These represent a detection limit of about 200 ppb and a maximum concentration of about 10% in a 0.5mL sample. Both values are dependent upon peak width.
Catalyst poisoning
Nickel catalyst methanizers have been known to undergo deactivation with certain elements and compounds:
H2S. Very small amounts of H2S, SF6, and probably any other sulfur containing gases, cause immediate and complete deactivation of the catalyst. It is not possible to regenerate a poisoned catalyst that has been deactivated by sulfur, by treating with either oxygen or hydrogen. If sulfur containing gases are present in the sample, a switching valve should be used either to bypass the catalyst, or to back-flush the column to vent after elution of CO2.
Air or O2. Reports of oxygen poisoning seem to be rather rumors than real facts. Small amounts of air through a catalyst will not kill it but anything over about 5 cc/min will cause an immediate and continual degradation of the catalyst. This has been seen first hand on several systems over 30 years of personal experience with a catalytic FID designed for analysis of U.S. EPA Method 25 and 25-C samples.
Unsaturated hydrocarbons. Samples of pure ethylene cause immediate, but partial, degradation of the catalyst, evidenced by slight tailing of CO and CO2 peaks. The effect of 2 or 3 samples might be tolerable, but since it is cumulative, such gases should be back-flushed or by-passed. Low concentrations do not cause any degradation. Samples of pure acetylene affect the catalyst much more severely than does ethylene. Low concentrations have no effect. Probably some carbonization with high concentrations of unsaturates occurs, resulting in the deposit of soot on the catalyst surface. It is likely that aromatics would have the same effect.
Other compounds. Water has no effect on the catalyst, as well as various Freons and NH3. Here again, with NH3, there is conflicting evidence from some users, who have seen a degradation after several injections, but other researchers were not able to confirm it. As with sulfur containing gases, NH3 can be back-flushed to vent or by-passed if desired.
Troubleshooting
In general, the catalyst works perfectly unless it is degraded by sample components, possible minute amounts of sulfur gases at otherwise undetectable levels. The effect is always the same — the CO and CO2 peaks start to tail. If only CO tails, it might well be a column effect, e.g., a Mol. Sieve 13X always causes slight tailing of CO. If the tailing is minimal, raising the catalyst temperature might provide enough improvement to permit further use.
With a newly packed nickel catalyst, tailing usually indicates that part of the catalyst bed is not hot enough. This can happen if the bed extends too far up the arms of the U-tube. Possibly a longer bed will improve the upper conversion limit, but if this is the aim, the packing must not extend beyond the confines of the heater block.
Catalyst preparation
No catalyst preparation is required with a 3D printed jet.
For nickel catalyst methanizers:
Dissolve 1g of nickel nitrate Ni(NO3)2•6H2O in 4-5mL of methanol. Add 10g of Chromosorb G. A/W, 80-100 mesh. There should be just enough methanol to completely wet the support without excess. Mix the slurry, pour into a flat Pyrex pan and dry on a hot plate at about 80-90°C with occasional gentle shaking or mixing. When dry, heat in air at about 400°C to decompose the salt to NiO. Note that NO2 is emitted during baking — provide adequate ventilation. About an hour at 400°C, longer at lower temperatures, will be needed to complete the process. After baking, the material is dark gray, with no trace of the original green.
Pour the raw catalyst into both arms of an 8"×1/8" nickel U-tube, checking the depth in both with a wire. The final bed should extend 3/8" to 1/2" above the bottom of the U in both arms. Plug with glass wool and install in the injector block.
Disadvantages
Traditional nickel catalyst methanizers are designed to only convert CO and CO2 to methane. Due to this limitation, deactivation commonly occurs when other compounds are present in the sample matrix, such as olefins and sulfur containing compounds. Thus, the use of methanizers often requires complex valve systems that may include backflush and heartcutting. Nickel catalyst replacement and conditioning steps are time consuming and require operator skill to perform properly.
Alternatives
Jetanizer
An alternative methanizer design known as the Jetanizer, where the methanizer is fully contained in a 3D-printed FID jet with novel catalyst, is available from Activated Research Company. The Jetanizer utilizes the heater and hydrogen supply of the FID, reducing the need for additional fittings and temperature control. Similarly to the polyarc reactor, the Jetanizer is resilient to poisoning by compounds containing sulfur, halogens, nitrogen, oxygen, and others. A limitation includes its inability to convert compounds other than CO and CO2 to methane. Literature has been published in the American Chemical Society and the Journal of Separation Science explaining the industry changing benefits of the design which is approachable by any skill level of GC operator given its optimized and simplistic design.
Polyarc reactor
A post-column reactor that overcomes methanizer limitations is a two-step oxidation-reduction reactor that converts nearly all organic compounds to methane. This technique enables the accurate quantification of any number of compounds that contain carbon beyond just CO and CO2, including those with low sensitivity in the FID such as carbon disulfide (CS2), carbonyl sulfide (COS), hydrogen cyanide (HCN), formamide (CH3NO), formaldehyde (CH2O) and formic acid (CH2O2). In addition to increasing the sensitivity of the FID to particular compounds, the response factors of all species become equivalent to that of methane, thereby minimizing or eliminating the need for calibration curves and the standards they rely on. The reactor is available exclusively from Activated Research Company and is known as the Polyarc reactor.
References
Gas chromatography
Catalysts | Methanizer | [
"Chemistry"
] | 1,879 | [
"Chromatography",
"Catalysts",
"Catalysis",
"Chemical kinetics",
"Gas chromatography"
] |
39,935,334 | https://en.wikipedia.org/wiki/Nokia%20Lumia%201020 | The Nokia Lumia 1020 (known as Lumia 909 during development) is a smartphone developed by Nokia, first unveiled on 11 July 2013 at a Nokia event in New York. It runs Windows Phone 8, but is also Windows Phone 8.1 ready. It contains Nokia's PureView technology, a pixel oversampling technique that reduces an image taken at full resolution into a lower resolution picture, thus achieving higher definition and light sensitivity, and enables lossless digital zoom. It improves on its predecessor, the Nokia 808, by coupling a 41-megapixel 2/3-inch BSI sensor with optical image stabilization (OIS) and a high resolution f/2.2 all-aspherical 1-group Carl Zeiss lens. It was considered to be the most advanced cameraphone when released in September 2013.
In January 2014, Nokia released the "Lumia Black" firmware update for the Lumia 1020, adding various new features, including improved image processing in addition to capturing RAW (DNG) files. The Lumia 1020 also received the Lumia Denim software update, but without new features or updates to the system firmware, due to the phone's age. It is not officially eligible for upgrading to Windows 10 Mobile.
A prototype codenamed McLaren (previously leaked as Goldfinger) was planned to be the successor to the 1020, but was cancelled before official launch.
PureView Pro camera
PureView Pro is an imaging technology used in the Nokia 1020 device. It is the combination of a 1/1.5" large, high-resolution 41 MP image sensor with high performance Carl Zeiss optics. The large sensor enables pixel oversampling, which means the combination of many sensor pixels into one image pixel. PureView imaging technology delivers high image quality, lossless zoom, and improved low light performance (see below). It dispenses with the usual scaling/interpolation model of digital zoom used in virtually all smartphones. In both video and stills, this technique provides greater zoom levels as the output picture size reduces, enabling 4× lossless zoom in 1080p video and 6× lossless zoom for 720p video. Optical image stabilization is also present to nullify shaking of hands when taking a photo and to allow significantly more light to enter the sensor for better low light photos. It also has an adjustable shutter speed of up to 1/16,000 s.
Some reviewers have noted the camera may exhibit lens flare and minor white balance issues under particular circumstances.
The camera needs 6.1 seconds to start up and 3.6 seconds between photo shots for 5 MP photos and 4.2 seconds for 38 MP photos.
Like the Nokia 808 (and the N8 and N82 before them), the Nokia Lumia 1020 has a Xenon flash.
PureView Pro specifications
Sensor
The Nokia Lumia 1020 has a 41.3-megapixel BSI CMOS image sensor, 1/1.5-inch (2/3-inch) image sensor format with a total of 7712 × 5360 pixels. Maximum image size at a 4:3 aspect ratio is 7136 × 5360 pixels (38.2 MP); maximum image size at a 16:9 aspect ratio is 7712 × 4352 pixels (33.6 MP). Pixel size is 1.12 μm. Sensor size is 8.80×6.60 mm. Crop factor 3.93×.35 mm equivalent focal length: 25 mm for 16:9, 27 mm for 4:3. f/2.2
Compare
The Nokia 808 has a 41.5-megapixel FSI CMOS image sensor, 1/1.2-inch image sensor format with an active area of 7728 × 5368 pixels, totalling over 41 MP. Depending on the aspect ratio chosen by the user, it will use 7728 × 4354 pixels (33.6 MP) for 16:9 images, or 7152 × 5368 pixels (38.2 MP) for 4:3 images with the default camera app. Pixel size is 1.4 μm. Sensor size is 10.67 × 8.00 mm. Crop factor 3.2×.35 mm equivalent focal length: 26 mm, 16:9 | 28 mm, 4:3. f/2.4
Lens
Carl Zeiss optics with f/2.2 focal ratio. Focal length: 7.2 mm: 35 mm equivalent focal length: 25 mm @ 16:9 aspect ratio, and 27 mm @ 4:3 aspect ratio. Construction: Six elements in one group. All lens surfaces are aspherical, partly extreme aspheric, one high refractive index, low-dispersion glass mould lens.
Optical image stabilisation — includes new type of barrel shift actuator, which enables moving a heavy and complex full-lens assembly.
Shutter
Mechanical shutter with short shutter lag.
Microphones
Lumia 1020 has high quality microphones for stereo recording of video's audio. Like in Nokia 808, Rich Recording technology (aka High Amplitude Audio Capture (HAAC)) is used that can capture sounds at the loudness level of up to 140 decibels without distortion.
Processing
On-chip image processor performing image scaling with oversampling, giving lossless zoom: 4× for full-HD 1080p video with on-chip video processor performing image resolution processing with over 1 billion pixels per second, enabling the use of all pixels for improved image noise and dynamic range.
Nokia Pro Camera software
The Lumia 1020 ships with Nokia's new Pro Camera application, allowing a greater degree of control over the camera settings than the standard Windows Phone in-built camera and can be set as the default imaging application when launched with the camera button. Providing "swipe-able" dials in a concentric ring display, settings such as exposure level, white balance, shutter speed and film ISO can be adjusted "on the fly" to enable changes to be visualised before a shot is taken. Nokia hope to bring professional camera settings, once the preserve of experts, to the masses and encourage experimentation and learning using built-in tutorials.
For video recording in addition to automatic control, manual focus and white balance controls are provided. Frame rate can be selected to be 24, 25 or 30 frames per second for both 720p and 1080p resolutions. For video's audio recording the HAAC high pass filter corner frequency can be selected to be 200 Hz, 100 Hz or none (0 Hz) in the settings. Selecting 200 Hz makes possible undistorted recording even in very loud surroundings having high bass audio levels.
Model variants
Reception
Reception was mainly positive, but some reviewers noted that the market for the Lumia 1020 is limited.
Kamalahasan from KnowYourGadget stated: "Nokia Lumia 1020 is a great improvement over the Nokia 808. The camera is just superb and one of the best we have seen on a mobile device. If you need a simple smartphone and your phone doubles as your point and shoot, this is the device for you.
Brian Klug from Anandtech stated: "I think it's fair to say that once again Nokia has basically set the bar for the rest of the smartphone imaging world – in terms of both hardware and software features."
Chris Finnamore from Expert Reviews wrote: "Simply stunning photos make the Lumia 1020 the ultimate cameraphone." He gave it five stars and awarded it the Expert Reviews: Ultimate award, which places it among other high-end flagships such as the Galaxy S4 and the iPhone 5S, which also received the award.
Erin Lodi of Digital Photography Review wrote: "Despite the lower lighting level, the Nokia is able to out-perform its rivals by a healthy margin. Fine detail is better maintained and the image is generally "cleaner." This benefit (that comes from a combination of a larger sensor and the noise-reducing effect of downscaling images), is one of the significant advantages of Nokia's decision to use a large sensor in a smartphone. Whether you look at the resolution stripe on the left of the image or the etched portrait on the right, the 1020 is significantly out-performing its rivals."
David Pierce from The Verge said that this is a remarkable phone, hampered by its operating system.
Dan Nosowitz from Popular Science wrote: "Nokia's new Lumia smartphone has amazing hardware (especially its unprecedented 41-megapixel camera). And it doesn't matter at all, because its software lags so far behind its hardware."
Charles Arthur from The Guardian wrote: "The Finnish phone maker released its remarkable Lumia 1020 phone with a 41-megapixel camera – but it's still missing native apps for low-quality Instagram, Vine and Snapchat"
Jim Fisher and Sascha Segan from PC Magazine wrote: "The Lumia 1020 is a big step forward for camera phones, but the step isn't complete. Nokia's sensor and lens advances must be paired with a CPU and image processor fast enough to make shooting effortless, and Windows Phone's creative app gaps need to be filled in."
G van Veldhoven from Gadgetmania wrote: "If you absolutely need the best camera on a smartphone and don't mind Windows Phone 8 and spending a good chunk of money upfront, the Lumia 1020 is worth looking at, but I don't expect it to be very popular."
Devindra Hardawar of VentureBeat called the Lumia 1020 "the best smartphone camera ever", but noted that the phone was "clearly being held back" by the Windows Phone operating system.
Sales were slower than the Lumia 920 and the previous Lumia 900, but slightly better than the Lumia 928.
Reported problems
Some Lumia 1020 users have reported instances of rapid battery drain and overheating, random reboots or freezes, poor voice call quality or Wi-Fi drop outs.
The Windows Phone 8.1 update introduced an issue for some Lumia 1020 and 925 users where their phones would freeze randomly on a regular basis. Microsoft has been working on the issue since September 2014.
In popular culture
The Lumia 1020 has been featured in several music videos and television shows, including:
"Roar" by Katy Perry
"I Can't Make You Love Me" by Priyanka Chopra
"How Long Will I Love You" by Ellie Goulding, with the video itself also shot on a Lumia 1020
Parks and Recreation
See also
Microsoft Lumia
References
External links
Nokia Lumia 1020 device specification
Nokia 1020 Pureview sample, review and user images, >20 MPix
Apps
Windows Phone App for view and edit Pureview (dng) files
Windows Phone
Lumia
Microsoft Lumia
Windows Phone devices
PureView
Mobile phones introduced in 2013
Discontinued flagship smartphones | Nokia Lumia 1020 | [
"Technology"
] | 2,248 | [
"Discontinued flagship smartphones",
"Flagship smartphones"
] |
39,936,262 | https://en.wikipedia.org/wiki/Homology%20%28psychology%29 | Homology in psychology, as in biology, refers to a relationship between characteristics that reflects the characteristics' origins in either evolution or development. Homologous behaviors can theoretically be of at least two different varieties. As with homologous anatomical characteristics, behaviors present in different species can be considered homologous if they are likely present in those species because the behaviors were present in a common ancestor of the two species. Alternatively, in much the same way as reproductive structures (e.g., the penis and the clitoris) are considered homologous because they share a common origin in embryonic tissues, behaviors—or the neural substrates associated with those behaviors—can also be considered homologous if they share common origins in development.
Behavioral homologies have been considered since at least 1958, when Konrad Lorenz studied the evolution of behavior. More recently, the question of behavioral homologies has been addressed by philosophers of science such as Marc Ereshefsky, psychologists such as Drew Rendall, and neuroscientists such as Georg Striedter and Glenn Northcutt. It is debatable whether the concept of homology is useful in developmental psychology.
For example, D. W. Rajecki and Randall C. Flanery, using data on humans and on nonhuman primates, argue that patterns of behaviour in dominance hierarchies are homologous across the primates.
References
Developmental psychology
Behavior
Evolutionary biology
Behavioural sciences | Homology (psychology) | [
"Biology"
] | 296 | [
"Behavioural sciences",
"Behavior",
"Evolutionary biology",
"Developmental psychology"
] |
39,937,576 | https://en.wikipedia.org/wiki/Hunt%20for%20Exomoons%20with%20Kepler | The Hunt for Exomoons with Kepler (HEK) is a project whose aim is to search for exomoons, natural satellites of exoplanets, using data collected by the Kepler space telescope. Founded by British exomoonologist David Kipping and affiliated with the Center for Astrophysics Harvard & Smithsonian, HEK submitted its first paper on June 30, 2011. HEK has since submitted five more papers, finding some evidence for an exomoon around a planet orbiting Kepler-1625b in July 2017.
Scientific work
HEK searches for exomoons in two ways, radial-velocity variation and transit-timing variation, both of which are based on alterations to the basic signal produced by the planet. For moons detected the first way, the sinusoidal changes in the wavelength of the light of the host star created by the planet may themselves be modulated slightly by a moon of the planet. In the second method, the interval at which a planet transits its host star may be made slightly shorter or longer under the gravitational influence of a moon, revealing its existence.
In its first paper, the Hunt for Exomoons with Kepler selected several Kepler planet candidates as search targets, based on the probability and detectability of potential moons around the planets. A second paper, published in early 2013, covering the properties of seven of the planet candidates, revealed no moons but allowed the astronomers to constrain the moon-to-planet mass ratios for the planets. A third paper, accepted by the Astrophysical Journal, analyzed the transit and radial-velocity signals of Kepler-22b, the first and only habitable-zone planet analyzed by the HEK team as of July 2013. As with previous searches, though, no moons were conclusively discovered, constraining the maximum mass of a Kepler-22b moon below 0.54 Earth masses with 95% confidence.
Despite the lack of positive results in one-and-a-half years of operation, several commentators, including Shannon Hall of Universe Today and Markus Hammonds of Discovery News, have expressed hope that there are billions of exomoons, many habitable, remaining to be found in the Milky Way. Citing the fact that the first exoplanets were not found in the first discovery efforts, and the fact that the Milky Way is extremely large and diverse, both commentators contend that exomoons will be found eventually.
In July 2017, the project reported weak evidence for a set of Io-like moons, and evidence for a moon around the planet orbiting Kepler-1625.
References
Exoplanet search projects
Kepler space telescope | Hunt for Exomoons with Kepler | [
"Astronomy"
] | 527 | [
"Astronomy projects",
"Exoplanet search projects",
"Space telescopes",
"Kepler space telescope"
] |
39,937,659 | https://en.wikipedia.org/wiki/Eigenstate%20thermalization%20hypothesis | The eigenstate thermalization hypothesis (or ETH) is a set of ideas which purports to explain when and why an isolated quantum mechanical system can be accurately described using equilibrium statistical mechanics. In particular, it is devoted to understanding how systems which are initially prepared in far-from-equilibrium states can evolve in time to a state which appears to be in thermal equilibrium. The phrase "eigenstate thermalization" was first coined by Mark Srednicki in 1994, after similar ideas had been introduced by Josh Deutsch in 1991. The principal philosophy underlying the eigenstate thermalization hypothesis is that instead of explaining the ergodicity of a thermodynamic system through the mechanism of dynamical chaos, as is done in classical mechanics, one should instead examine the properties of matrix elements of observable quantities in individual energy eigenstates of the system.
Motivation
In statistical mechanics, the microcanonical ensemble is a particular statistical ensemble which is used to make predictions about the outcomes of experiments performed on isolated systems that are believed to be in equilibrium with an exactly known energy. The microcanonical ensemble is based upon the assumption that, when such an equilibrated system is probed, the probability for it to be found in any of the microscopic states with the same total energy have equal probability. With this assumption, the ensemble average of an observable quantity is found by averaging the value of that observable over all microstates with the correct total energy:
Importantly, this quantity is independent of everything about the initial state except for its energy.
The assumptions of ergodicity are well-motivated in classical mechanics as a result of dynamical chaos, since a chaotic system will in general spend equal time in equal areas of its phase space. If we prepare an isolated, chaotic, classical system in some region of its phase space, then as the system is allowed to evolve in time, it will sample its entire phase space, subject only to a small number of conservation laws (such as conservation of total energy). If one can justify the claim that a given physical system is ergodic, then this mechanism will provide an explanation for why statistical mechanics is successful in making accurate predictions. For example, the hard sphere gas has been rigorously proven to be ergodic.
This argument cannot be straightforwardly extended to quantum systems, even ones that are analogous to chaotic classical systems, because time evolution of a quantum system does not uniformly sample all vectors in Hilbert space with a given energy. Given the state at time zero in a basis of energy eigenstates
the expectation value of any observable is
Even if the are incommensurate, so that this expectation value is given for long times by
the expectation value permanently retains knowledge of the initial state in the form of the coefficients .
In principle it is thus an open question as to whether an isolated quantum mechanical system, prepared in an arbitrary initial state, will approach a state which resembles thermal equilibrium, in which a handful of observables are adequate to make successful predictions about the system. However, a variety of experiments in cold atomic gases have indeed observed thermal relaxation in systems which are, to a very good approximation, completely isolated from their environment, and for a wide class of initial states. The task of explaining this experimentally observed applicability of equilibrium statistical mechanics to isolated quantum systems is the primary goal of the eigenstate thermalization hypothesis.
Statement
Suppose that we are studying an isolated, quantum mechanical many-body system. In this context, "isolated" refers to the fact that the system has no (or at least negligible) interactions with the environment external to it. If the Hamiltonian of the system is denoted , then a complete set of basis states for the system is given in terms of the eigenstates of the Hamiltonian,
where is the eigenstate of the Hamiltonian with eigenvalue . We will refer to these states simply as "energy eigenstates." For simplicity, we will assume that the system has no degeneracy in its energy eigenvalues, and that it is finite in extent, so that the energy eigenvalues form a discrete, non-degenerate spectrum (this is not an unreasonable assumption, since any "real" laboratory system will tend to have sufficient disorder and strong enough interactions as to eliminate almost all degeneracy from the system, and of course will be finite in size). This allows us to label the energy eigenstates in order of increasing energy eigenvalue. Additionally, consider some other quantum-mechanical observable , which we wish to make thermal predictions about. The matrix elements of this operator, as expressed in a basis of energy eigenstates, will be denoted by
We now imagine that we prepare our system in an initial state for which the expectation value of is far from its value predicted in a microcanonical ensemble appropriate to the energy scale in question (we assume that our initial state is some superposition of energy eigenstates which are all sufficiently "close" in energy). The eigenstate thermalization hypothesis says that for an arbitrary initial state, the expectation value of will ultimately evolve in time to its value predicted by a microcanonical ensemble, and thereafter will exhibit only small fluctuations around that value, provided that the following two conditions are met:
The diagonal matrix elements vary smoothly as a function of energy, with the difference between neighboring values, , becoming exponentially small in the system size.
The off-diagonal matrix elements , with , are much smaller than the diagonal matrix elements, and in particular are themselves exponentially small in the system size.
These conditions can be written as
where and are smooth functions of energy, is the many-body Hilbert space dimension, and is a random variable with zero mean and unit variance. Conversely if a quantum many-body system satisfies the ETH, the matrix representation of any local operator in the energy eigen basis is expected to follow the above ansatz.
Equivalence of the diagonal and microcanonical ensembles
We can define a long-time average of the expectation value of the operator according to the expression
If we use the explicit expression for the time evolution of this expectation value, we can write
The integration in this expression can be performed explicitly, and the result is
Each of the terms in the second sum will become smaller as the limit is taken to infinity. Assuming that the phase coherence between the different exponential terms in the second sum does not ever become large enough to rival this decay, the second sum will go to zero, and we find that the long-time average of the expectation value is given by
This prediction for the time-average of the observable is referred to as its predicted value in the diagonal ensemble, The most important aspect of the diagonal ensemble is that it depends explicitly on the initial state of the system, and so would appear to retain all of the information regarding the preparation of the system. In contrast, the predicted value in the microcanonical ensemble is given by the equally-weighted average over all energy eigenstates within some energy window centered around the mean energy of the system
where is the number of states in the appropriate energy window, and the prime on the sum indices indicates that the summation is restricted to this appropriate microcanonical window. This prediction makes absolutely no reference to the initial state of the system, unlike the diagonal ensemble. Because of this, it is not clear why the microcanonical ensemble should provide such an accurate description of the long-time averages of observables in such a wide variety of physical systems.
However, suppose that the matrix elements are effectively constant over the relevant energy window, with fluctuations that are sufficiently small. If this is true, this one constant value A can be effectively pulled out of the sum, and the prediction of the diagonal ensemble is simply equal to this value,
where we have assumed that the initial state is normalized appropriately. Likewise, the prediction of the microcanonical ensemble becomes
The two ensembles are therefore in agreement.
This constancy of the values of over small energy windows is the primary idea underlying the eigenstate thermalization hypothesis. Notice that in particular, it states that the expectation value of in a single energy eigenstate is equal to the value predicted by a microcanonical ensemble constructed at that energy scale. This constitutes a foundation for quantum statistical mechanics which is radically different from the one built upon the notions of dynamical ergodicity.
Tests
Several numerical studies of small lattice systems appear to tentatively confirm the predictions of the eigenstate thermalization hypothesis in interacting systems which would be expected to thermalize. Likewise, systems which are integrable tend not to obey the eigenstate thermalization hypothesis.
Some analytical results can also be obtained if one makes certain assumptions about the nature of highly excited energy eigenstates. The original 1994 paper on the ETH by Mark Srednicki studied, in particular, the example of a quantum hard sphere gas in an insulated box. This is a system which is known to exhibit chaos classically. For states of sufficiently high energy, Berry's conjecture states that energy eigenfunctions in this many-body system of hard sphere particles will appear to behave as superpositions of plane waves, with the plane waves entering the superposition with random phases and Gaussian-distributed amplitudes (the precise notion of this random superposition is clarified in the paper). Under this assumption, one can show that, up to corrections which are negligibly small in the thermodynamic limit, the momentum distribution function for each individual, distinguishable particle is equal to the Maxwell–Boltzmann distribution
where is the particle's momentum, m is the mass of the particles, k is the Boltzmann constant, and the "temperature" is related to the energy of the eigenstate according to the usual equation of state for an ideal gas,
where N is the number of particles in the gas. This result is a specific manifestation of the ETH, in that it results in a prediction for the value of an observable in one energy eigenstate which is in agreement with the prediction derived from a microcanonical (or canonical) ensemble. Note that no averaging over initial states whatsoever has been performed, nor has anything resembling the H-theorem been invoked. Additionally, one can also derive the appropriate Bose–Einstein or Fermi–Dirac distributions, if one imposes the appropriate commutation relations for the particles comprising the gas.
Currently, it is not well understood how high the energy of an eigenstate of the hard sphere gas must be in order for it to obey the ETH. A rough criterion is that the average thermal wavelength of each particle be sufficiently smaller than the radius of the hard sphere particles, so that the system can probe the features which result in chaos classically (namely, the fact that the particles have a finite size ). However, it is conceivable that this condition may be able to be relaxed, and perhaps in the thermodynamic limit, energy eigenstates of arbitrarily low energies will satisfy the ETH (aside from the ground state itself, which is required to have certain special properties, for example, the lack of any nodes ).
Alternatives
Three alternative explanations for the thermalization of isolated quantum systems are often proposed:
For initial states of physical interest, the coefficients exhibit large fluctuations from eigenstate to eigenstate, in a fashion which is completely uncorrelated with the fluctuations of from eigenstate to eigenstate. Because the coefficients and matrix elements are uncorrelated, the summation in the diagonal ensemble is effectively performing an unbiased sampling of the values of over the appropriate energy window. For a sufficiently large system, this unbiased sampling should result in a value which is close to the true mean of the values of over this window, and will effectively reproduce the prediction of the microcanonical ensemble. However, this mechanism may be disfavored for the following heuristic reason. Typically, one is interested in physical situations in which the initial expectation value of is far from its equilibrium value. For this to be true, the initial state must contain some sort of specific information about , and so it becomes suspect whether or not the initial state truly represents an unbiased sampling of the values of over the appropriate energy window. Furthermore, whether or not this were to be true, it still does not provide an answer to the question of when arbitrary initial states will come to equilibrium, if they ever do.
For initial states of physical interest, the coefficients are effectively constant, and do not fluctuate at all. In this case, the diagonal ensemble is precisely the same as the microcanonical ensemble, and there is no mystery as to why their predictions are identical. However, this explanation is disfavored for much the same reasons as the first.
Integrable quantum systems are proved to thermalize under condition of simple regular time-dependence of parameters, suggesting that cosmological expansion of the Universe and integrability of the most fundamental equations of motion are ultimately responsible for thermalization.
Temporal fluctuations of expectation values
The condition that the ETH imposes on the diagonal elements of an observable is responsible for the equality of the predictions of the diagonal and microcanonical ensembles. However, the equality of these long-time averages does not guarantee that the fluctuations in time around this average will be small. That is, the equality of the long-time averages does not ensure that the expectation value of will settle down to this long-time average value, and then stay there for most times.
In order to deduce the conditions necessary for the observable's expectation value to exhibit small temporal fluctuations around its time-average, we study the mean squared amplitude of the temporal fluctuations, defined as
where is a shorthand notation for the expectation value of at time t. This expression can be computed explicitly, and one finds that
Temporal fluctuations about the long-time average will be small so long as the off-diagonal elements satisfy the conditions imposed on them by the ETH, namely that they become exponentially small in the system size. Notice that this condition allows for the possibility of isolated resurgence times, in which the phases align coherently in order to produce large fluctuations away from the long-time average. The amount of time the system spends far away from the long-time average is guaranteed to be small so long as the above mean squared amplitude is sufficiently small. If a system poses a dynamical symmetry, however, it will periodically oscillate around the long-time average.
Quantum fluctuations and thermal fluctuations
The expectation value of a quantum mechanical observable represents the average value which would be measured after performing repeated measurements on an ensemble of identically prepared quantum states. Therefore, while we have been examining this expectation value as the principal object of interest, it is not clear to what extent this represents physically relevant quantities. As a result of quantum fluctuations, the expectation value of an observable is not typically what will be measured during one experiment on an isolated system. However, it has been shown that for an observable satisfying the ETH, quantum fluctuations in its expectation value will typically be of the same order of magnitude as the thermal fluctuations which would be predicted in a traditional microcanonical ensemble. This lends further credence to the idea that the ETH is the underlying mechanism responsible for the thermalization of isolated quantum systems.
General validity
Currently, there is no known analytical derivation of the eigenstate thermalization hypothesis for general interacting systems. However, it has been verified to be true for a wide variety of interacting systems using numerical exact diagonalization techniques, to within the uncertainty of these methods. It has also been proven to be true in certain special cases in the semi-classical limit, where the validity of the ETH rests on the validity of Shnirelman's theorem, which states that in a system which is classically chaotic, the expectation value of an operator in an energy eigenstate is equal to its classical, microcanonical average at the appropriate energy. Whether or not it can be shown to be true more generally in interacting quantum systems remains an open question. It is also known to explicitly fail in certain integrable systems, in which the presence of a large number of constants of motion prevent thermalization.
It is also important to note that the ETH makes statements about specific observables on a case-by-case basis - it does not make any claims about whether every observable in a system will obey ETH. In fact, this certainly cannot be true. Given a basis of energy eigenstates, one can always explicitly construct an operator which violates the ETH, simply by writing down the operator as a matrix in this basis whose elements explicitly do not obey the conditions imposed by the ETH. Conversely, it is always trivially possible to find operators which do satisfy ETH, by writing down a matrix whose elements are specifically chosen to obey ETH. In light of this, one may be led to believe that the ETH is somewhat trivial in its usefulness. However, the important consideration to bear in mind is that these operators thus constructed may not have any physical relevance. While one can construct these matrices, it is not clear that they correspond to observables which could be realistically measured in an experiment, or bear any resemblance to physically interesting quantities. An arbitrary Hermitian operator on the Hilbert space of the system need not correspond to something which is a physically measurable observable.
Typically, the ETH is postulated to hold for "few-body operators," observables which involve only a small number of particles. Examples of this would include the occupation of a given momentum in a gas of particles, or the occupation of a particular site in a lattice system of particles. Notice that while the ETH is typically applied to "simple" few-body operators such as these, these observables need not be local in space - the momentum number operator in the above example does not represent a local quantity.
There has also been considerable interest in the case where isolated, non-integrable quantum systems fail to thermalize, despite the predictions of conventional statistical mechanics. Disordered systems which exhibit many-body localization are candidates for this type of behavior, with the possibility of excited energy eigenstates whose thermodynamic properties more closely resemble those of ground states. It remains an open question as to whether a completely isolated, non-integrable system without static disorder can ever fail to thermalize. One intriguing possibility is the realization of "Quantum Disentangled Liquids." It also an open question whether all eigenstates must obey the ETH in a thermalizing system.
The eigenstate thermalization hypothesis is closely connected to the quantum nature of chaos (see quantum chaos). Furthermore, since a classically chaotic system is also ergodic, almost all of its trajectories eventually explore uniformly the entire accessible phase space, which would imply the eigenstates of the quantum chaotic system fill the quantum phase space evenly (up to random fluctuations) in the semiclassical limit . In particular, there is a quantum ergodicity theorem showing that the expectation value of an operator converges to the corresponding microcanonical classical average as . However, the quantum ergodicity theorem leaves open the possibility of non-ergodic states such as quantum scars. In addition to the conventional scarring, there are two other types of quantum scarring, which further illustrate the weak-ergodicity breaking in quantum chaotic systems: perturbation-induced and many-body quantum scars. Since the former arise a combined effect of special nearly-degenerate unperturbed states and the localized nature of the perturbation (potential bums), the scarring can slow down the thermalization process in disordered quantum dots and wells, which is further illustrated by the fact that these quantum scars can be used to propagate quantum wave packets in a disordered nanostructure with high fidelity. On the other hand, the latter form of scarring has been speculated to be the culprit behind the unexpectedly slow thermalization of cold atoms observed experimentally.
See also
Equilibrium thermodynamics
Fluctuation dissipation theorem
Important Publications in Statistical Mechanics
Non-equilibrium thermodynamics
Quantum thermodynamics
Statistical physics
Configuration entropy
Chaos Theory
Hard spheres
Quantum statistical mechanics
Microcanonical Ensemble
H-theorem
Adiabatic theorem
Footnotes
References
External links
"Overview of Eigenstate Thermalization Hypothesis" by Mark Srednicki, UCSB, KITP Program: Quantum Dynamics in Far from Equilibrium Thermally Isolated Systems
"The Eigenstate Thermalization Hypothesis" by Mark Srednicki, UCSB, KITP Rapid Response Workshop: Black Holes: Complementarity, Fuzz, or Fire?
"Quantum Disentangled Liquids" by Matthew P. A. Fisher, UCSB, KITP Conference: From the Renormalization Group to Quantum Gravity Celebrating the science of Joe Polchinski
Hypotheses
Quantum mechanics
Statistical mechanics
Thermodynamics | Eigenstate thermalization hypothesis | [
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39,937,914 | https://en.wikipedia.org/wiki/Convention%20on%20Early%20Notification%20of%20a%20Nuclear%20Accident | The Convention on Early Notification of a Nuclear Accident is a 1986 International Atomic Energy Agency (IAEA) treaty whereby states have agreed to provide notification of any nuclear accident that occur within its jurisdiction that could affect other states. It, along with the Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency, was adopted in direct response to the April 1986 Chernobyl disaster.
By agreeing to the Convention, a state acknowledges that when any nuclear or radiation accident occurs within its territory that has the potential of affecting another state, it will promptly notify the IAEA and the other states that could be affected. The information to be reported includes the incident's time, location, and the suspected amount of radioactivity release.
The Convention was concluded and signed at a special session of the IAEA general conference on 26 September 1986; the special session was called because of the Chernobyl disaster, which had occurred five months before. Significantly, the Soviet Union and the Ukrainian SSR—the states that were responsible for the Chernobyl disaster—both signed the treaty at the conference and quickly ratified it. It was signed by 69 states and the Convention entered into force on 27 October 1986 after the third ratification.
As of 2021, 115 state parties are full participants in the Convention, along with the European Atomic Energy Community, the Food and Agriculture Organization, the World Health Organization, and the World Meteorological Organization. A further 8 states have signed the treaty but not ratified it - Afghanistan, Democratic Republic of the Congo, Holy See, Niger, North Korea, Sierra Leone, Sudan, and Zimbabwe.
Technical Implementation
To implement the agreement, the IAEA operates the web portal USIE. National competent authorities can use this web portal to fulfill their information and reporting obligations in case of an emergency. Alternative reporting methods and a description of further details are outlined in the corresponding IAEA Operations Manual for Incident and Emergency Communication.
See also
European Community Urgent Radiological Information Exchange
References
External links
Convention on Early Notification of a Nuclear Accident, IAEA information page.
Text of the Convention.
Signatures and ratifications.
1986 in Austria
Aftermath of the Chernobyl disaster
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Treaties concluded in 1986
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Treaties of Bulgaria | Convention on Early Notification of a Nuclear Accident | [
"Chemistry",
"Technology",
"Engineering"
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39,938,071 | https://en.wikipedia.org/wiki/White%20slave%20propaganda | White slave propaganda was a kind of publicity, especially photograph and woodcuts, and also novels, articles, and popular lectures, about slaves who were biracial or white in appearance. Their examples were used during and prior to the American Civil War to further the abolitionist cause and to raise money for the education of former slaves.
The images included children with predominantly European features photographed alongside dark-skinned adult slaves with typically African features. All these people, including the seemingly white children, were classified as black under the one-drop rule, as they had both black and white ancestry. It was intended to shock the viewing audiences with a reminder that slaves shared their humanity, and evidence that slaves did not belong in the category of the "Other".
Historical background
Sexual exploitation of slaves by their masters, master's sons, overseers, or other powerful white men was common in the United States. (See Children of the plantation.) By the 1860 Census, mixed-race slaves constituted about 10% of the 4 million slaves enumerated; they were more numerous in the Upper South. Slavery had existed for a longer time there, and in the generally smaller holdings, slaves had lived more closely with white workers and masters, leading to more contact between the groups. The scale of the sexual exploitation is suggested by research that show the DNA of contemporary African Americans is, on average, 24% European in origin.
An analysis of the WPA Slave Narrative Collection, collected in the 1930s, shows that, when women discussed parentage at all, about one-third of these women ex-slaves said they had given birth to a child with a white father, or were themselves the child of a white father. The plight of these mixed-race slaves, especially as children, was often publicized as a way to further the abolitionist cause.
Some pro-slavery activists wanted slavery legalized nationwide, overruling state prohibitions. They suggested there was no reason why slavery should be limited to blacks. They said that Northern white laborers would actually have better lives as slaves.
Abolitionist use of "white slaves"
Fiction
The first abolitionist novel, The Slave: or Memoirs of Archy Moore, published in 1836 by historian Richard Hildreth, features an enslaved mixed-race hero, son of a white planter and an enslaved mother, who is herself the daughter of a white planter. He can state that "both on the father's and the mother's side, I had running in my veins, the best blood of Virginia". When he and his sister decide to escape, they have no problems "in passing ourselves as white citizens." The title of the 1852 edition refers to the appearance of the hero: The White Slave; or, Memoirs of a Fugitive.
The character of Eliza in the 1852 novel Uncle Tom's Cabin was described as a quadroon slave (one-quarter black ancestry), whose child also appeared to be "all-but-white".
Another popular abolitionist novel of the time was Mary Hayden Pike's Ida May: a Story of Things Actual and Possible (1854), a story about a "white" slave. In 1855, Mary Mildred Botts, a young mixed-race slave who appeared white, gained freedom after her father got financial support from abolitionists to purchase her freedom as well as that of his wife and two other children. Among those who helped was US Senator Charles Sumner of Massachusetts. She was considered the embodiment of Ida May. Articles were published about her in the Boston Telegraph and the New York Times, and copies of her photograph were widely publicized. Botts accompanied Sumner and other abolitionists on stage; she sat with them while they lectured, and was described as a former slave. On May 19 and 20, 1856, Sumner spoke in the Senate, comparing Southern political positions to the sexual exploitation of slaves then taking place in the South. Two days later Sumner was beaten almost to death on the floor of the Senate in the Capitol by Representative Preston Brooks from South Carolina, known as a hothead.
Three decades after the Emancipation Proclamation, Frances Harper's 1892 novel Iola Leroy, or Shadows Uplifted tells the story of a "colored" family before and after emancipation. With the exception of Iola's grandmother, who is "unmistakably colored", all members of the family have so much European ancestry that they can easily pass for white. When Iola's uncle, Robert Johnson, escapes from slavery and distinguishes himself in the Union army, a white officer compares him to the other former slaves among his soldiers: "You do not look like them, you do not talk like them. It is a burning shame to have held such a man as you in slavery." Johnson answers: "I don't think it was any worse to have held me in slavery than the blackest man in the South."
Nonfiction
Nonfiction accounts written by escaped mixed-race slaves who used their European appearance to "pass for white" and gain freedom include Ellen Craft: Running a Thousand Miles for Freedom (coauthored with her husband William). With majority-white ancestry, Craft often also appeared as a speaker on the abolitionist lecture circuit.
The Crafts and other abolitionists also publicized the life of Salomé Müller, a German immigrant orphaned as an infant soon after arrival in New Orleans. Though Muller (later known as Sally Miller) was completely of European descent, she became enslaved as an infant, and was assumed to be a mixed-race slave. The threat of white girls being seized and thrown into slavery prompted Parker Pillsbury to write to William Lloyd Garrison: "A white skin is no security whatsoever. I should no more dare to send white children out to play alone, especially at night...than I should dare send them into a forest of tigers and hyenas."
Fannie Virginia Casseopia Lawrence was a young white slave freed in early 1863. She was adopted by Catherine S. Lawrence of New York and baptized by Henry Ward Beecher at the Plymouth Congregational Church in Brooklyn, New York. Carte de visite photographs of her were also sold to raise money for the abolitionist cause.
A special case: Freed slaves from Louisiana
By 1863 in Louisiana, ninety-five schools for freedmen, serving 9,500 students, were active in areas controlled by the Union Army. Funding was needed to continue to run the schools. The National Freedman's Association, the American Missionary Association, and Union officers launched a publicity campaign to raise money by selling carte de visite (CDV) photographs of eight former slaves, five children and three adults. The former slaves were accompanied on a tour of Philadelphia and New York by Colonel George H. Hanks. A woodcut, based on a photograph of the former slaves, appeared in Harper's Weekly in January 1864 with the caption "EMANCIPATED SLAVES, WHITE AND COLORED." Four of the children were predominantly white in appearance, although born into slavery.
The former slaves traveled from New Orleans to the North. Of these, four children appeared to be white or octoroon. According to the Harper's Weekly article, they were, perfectly white;' 'very fair;' 'of unmixed white race.' Their light complexions contrasted sharply with those of the three adults, Wilson, Mary, and Robert; and that of the fifth child, Isaac—'a black boy of eight years; but none the less intelligent than his whiter companions.
The group was accompanied by Colonel Hanks from the 18th Infantry Regiment. They posed for photos in New York City and in Philadelphia. The resulting images were produced in the carte de visite format and were sold for twenty-five cents each, with the profits of the sale being directed to Major General Nathaniel P. Banks back in Louisiana to support education of freedmen. Each of the photos noted that sale proceeds would be "devoted to the education of colored people".
Of the many prints that were commissioned, at least twenty-two remain in existence today. Most of these were produced by Charles Paxson and Myron Kimball, who took the group photo that later appeared as a woodcut in Harper's Weekly. A portrait of Rebecca was taken by James E. McClees of Philadelphia.
Modern analysis
Modern scholars have examined the white slave campaign's motives and success. Mary Niall Mitchell, in "Rosebloom and Pure White, Or So It Seemed", argues that because the slaves were depicted as being white, through both their skin color and style of dress, abolitionists could argue that the Civil War was independent of class status. Supporters of the war believed that this was needed after the New York City draft riots that year. Predominantly ethnic Irish mobs had protested the draft law, as wealthier men could buy substitutes rather than serve in the war.
Carol Goodman, in "Visualizing the Color Line", has argued that the photos alluded to physical and sexual abuse of the children's mothers. When publishing the photo of the eight former slaves, the editor of Harper's Weekly wrote that slavery permits slave-holding gentlemen' [to] seduce [the] most friendless and defenseless of women." The specter of "white" girls being sold as "fancy girls" or concubines in Southern slave markets may have caused Northern families to fear for the safety of their own daughters. Similarly, the idea that white slave-master fathers would sell their own children in slave markets raised Northerners' concerns.
Gwendolyn DuBois Shaw, in "Portraits of a People", has argued that the usage of props, such as the American flag and books, helped to provide context for Northern viewers, and also to emphasize that the purpose of the photos was to raise money for education of former slaves by funding schools in Louisiana. She also noted that the use of "white" children to illustrate the damage caused by institutional slavery, whose victims were overwhelmingly visibly people of color, demonstrated the contemporary racism of both Southern and Northern societies.
See also
Julia Chinn, common-law wife of vice president Richard Mentor Johnson
Wilson Chinn
Sally Hemings, whose children are generally regarded as having been fathered by president Thomas Jefferson
Irish slaves myth
Garafilia Mohalbi, a Greek girl rescued from slavery in the Ottoman Empire
Louisa Picquet
Passing (racial identity)
White slavery
Mary Mildred Williams
References
Notes
Further reading
See especially Ch.III
Fremont Campaign Literature, 1856
Henry Louis Gates, Jr., Exactly How ‘Black’ Is Black America?
External links
Image gallery
Abolitionism in the United States
Discrimination based on skin tone
Propaganda in the United States
Human skin color
Slavery in the United States | White slave propaganda | [
"Biology"
] | 2,160 | [
"Human skin color",
"Pigmentation"
] |
42,725,214 | https://en.wikipedia.org/wiki/Shapley-Ames%20Catalog | The Shapley-Ames Catalog of Bright Galaxies is a catalog of galaxies published in 1932 that includes observations of 1249 objects brighter than 13.2 magnitude. It was compiled by Harlow Shapley and Adelaide Ames. They identified 1189 objects based on the New General Catalogue and 48 based on the Index Catalogue. With the help of new photographic recordings, which also contained comparison stars of known brightness, the brightness of many galaxies were measured and recorded only up to a magnitude of 13.2. It was the first compilation of bright galaxies in the northern and southern sky. The catalog contains position, brightness, size, and Hubble classification of the galaxies. For the next 60 years, astronomers referred to this catalog as a primary source for information about redshifts and galaxy types.
History
Shapley and Ames began their study of all nearby galaxies in 1926. An important finding from this research was that the galaxies were not evenly distributed (they violated the isotropy assumption) in that the northern hemisphere contained more galaxies than the southern hemisphere. It also found that the Virgo cloud extended further than previously believed. From this data, Shapley and Ames therefore created a new hierarchy of clusters called a supercluster, which is a cluster of galaxy clusters, and called this Virgo cloud in the northern hemisphere a "Local Supercluster".
In 1981, Allan Sandage and Gustav Tammann published an updated version known as the Revised Shapley-Ames Catalog (RSA). The original list of galaxies was maintained, with the exception of three objects which were no longer considered galaxies. The information on the 1246 individual galaxies have been updated and substantially extended.
References
Astronomical catalogues
Astronomical catalogues of galaxies
Astronomical catalogues of galaxy clusters | Shapley-Ames Catalog | [
"Astronomy"
] | 355 | [
"Astronomical catalogues",
"Astronomical objects",
"Works about astronomy"
] |
42,725,971 | https://en.wikipedia.org/wiki/Brevifolin | Brevifolin is a bioactive compound found in pomegranate. The pharmacological profile of brevifolin is reported similar to ellagic acid, particularly with regards to absorption, distribution, and elimination rates.
References
Aromatic ketones
Natural phenols
Pomegranates | Brevifolin | [
"Chemistry"
] | 62 | [
"Biomolecules by chemical classification",
"Natural phenols"
] |
42,726,277 | https://en.wikipedia.org/wiki/Beryllium%20sulfide | Beryllium sulfide (BeS) is an ionic compound from the sulfide group with the formula BeS. It is a white solid with a sphalerite structure that is decomposed by water and acids.
Preparation
Beryllium sulfide powders can be prepared by the reaction of sulfur and beryllium in a hydrogen atmosphere by heating the mixture for 10-20 minutes at temperatures from 1000-1300 °C. If done at 900 °C, there is beryllium metal impurities.
Alternatively, it can be prepared by the reaction of beryllium chloride and hydrogen sulfide at 900 °C.
References
Beryllium compounds
Monosulfides
II-VI semiconductors
Zincblende crystal structure | Beryllium sulfide | [
"Chemistry"
] | 144 | [
"Semiconductor materials",
"II-VI semiconductors",
"Inorganic compounds",
"Inorganic compound stubs"
] |
42,726,901 | https://en.wikipedia.org/wiki/Intelligence%2C%20Surveillance%20and%20Reconnaissance%20Group | The Intelligence, Surveillance and Reconnaissance Group is a formation of the British Army that commands the Army's miniature UAS, tactical UAS, counter-intelligence and reach back intelligence capabilities, the Specialist Group Military Intelligence and the Land Intelligence Fusion Centre.
History
1st Intelligence, Surveillance and Reconnaissance Brigade
Under the Army 2020 programme, a larger emphasis was placed on cyber and specialist capabilities. As part of this reorganisation, the 1st Military Intelligence Brigade, the Royal Artillery's UAS regiments, Honourable Artillery Company and the two reserve Special Air Service (SAS) Regiments came under the command of the newly formed 1st Intelligence Surveillance and Reconnaissance Brigade. The new brigade was stood up on 1 September 2014 at Upavon and placed under Force Troops Command.
Intelligence, Surveillance and Reconnaissance Group
Under the Future Soldier programme announced on 25 November 2021, the brigade was reduced to a Colonel's Command, became the Intelligence, Surveillance, and Reconnaissance Group and transferred from the now disbanded 6th Division to Field Army Troops. The role of the group is to be to command the Army's miniature UAS, tactical UAS, counter-intelligence, and reach back intelligence capabilities, the Specialist Group Military Intelligence, and Land Intelligence Fusion Centre. It also commands the Land Image Intelligence Company, a pool of experts who deliver image analysis for all the Army's image collection platforms.
Structure
Before becoming ISR Group
Headquarters, 1st Intelligence, Surveillance, and Reconnaissance Brigade, at Trenchard Lines, Upavon
14 Signal Regiment (Electronic Warfare), Royal Corps of Signals, at Cawdor Barracks, Brawdy
2nd Military Intelligence (Exploitation) Battalion, Intelligence Corps, at Trenchard Lines, Upavon
3rd Military Intelligence Battalion, Intelligence Corps , in Hackney
4th Military Intelligence Battalion, Intelligence Corps, at Ward Barracks, Bulford Camp
6th Military Intelligence Battalion, Intelligence Corps , in Manchester – paired with 2 Military Intelligence Battalion
7th Military Intelligence Battalion, Intelligence Corps , in Bristol – paired with 4 Military Intelligence Battalion
32 Regiment Royal Artillery, at Roberts Barracks, Larkhill Garrison (UAV operations, with Lockheed Martin Desert Hawk III)
Specialist Group Military Intelligence, at Denison Barracks, Hermitage
Defence Intelligence Fusion Centre, at Denison Barracks, Hermitage
Defence Cultural and Linguistic Support Unit, at Denison Barracks, Hermitage
On formation in 2014
Headquarters 1st Intelligence and Surveillance Brigade, at Trenchard Lines, Upavon
14 Signal Regiment (Electronic Warfare), Royal Corps of Signals, at Cawdor Barracks, Brawdy
1 Military Intelligence Battalion, Intelligence Corps, at Bourlon Barracks, Catterick Garrison
2 Military Intelligence Battalion, Intelligence Corps, at Trenchard Lines, Upavon
3 Military Intelligence Battalion, Intelligence Corps), in Hackney, London – paired with 1 MI Bn
4 Military Intelligence Battalion, Intelligence Corps, at Ward Barracks, Bulford Camp
5 Military Intelligence Battalion, Intelligence Corps, in Edinburgh – paired with 1 MI Bn
6 Military Intelligence Battalion, Intelligence Corps, in Manchester – paired with 2 MI Bn
7 Military Intelligence Battalion, Intelligence Corps, in Bristol – paired with 4 MI Bn
5th Regiment, Royal Artillery, at Marne Barracks, Catterick Garrison
32 Regiment, Royal Artillery, at Roberts Barracks, Larkhill Garrison (Mini UAS)
47 Regiment, Royal Artillery, at Horne Barracks, Larkhill Garrison (Tactical UAVs)
104 Regiment, Royal Artillery, in Newport (Mini UAS) – paired with 32 & 47 Regiments RA
The Honourable Artillery Company, at Finsbury Barracks, Finsbury, London
21(Artists)(Reserve) SAS Regiment, at Albany Barracks, Regents Park, London
23(Reserve) SAS Regiment, at Kingstanding, Birmingham
Specialist Group Military Intelligence, at Denison Barracks, Hermitage
Defence Cultural Specialist Unit, at Denison Barracks, Hermitage
Land Intelligence Fusion Centre, at Denison Barracks, Hermitage
References
External links
1st Intelligence, Surveillance and Reconnaissance Brigade Website
Brigades of the British Army
Military intelligence units and formations of the United Kingdom
Military intelligence brigades
Army 2020
Military units and formations established in 2014
Organisations based in Wiltshire
Army reconnaissance units and formations | Intelligence, Surveillance and Reconnaissance Group | [
"Engineering"
] | 804 | [
"Army 2020",
"Military projects"
] |
42,726,919 | https://en.wikipedia.org/wiki/Deferred%20measurement%20principle | The deferred measurement principle is a result in quantum computing which states that delaying measurements until the end of a quantum computation doesn't affect the probability distribution of outcomes.
A consequence of the deferred measurement principle is that measuring commutes with conditioning.
The choice of whether to measure a qubit before, after, or during an operation conditioned on that qubit will have no observable effect on a circuit's final expected results.
Thanks to the deferred measurement principle, measurements in a quantum circuit can often be shifted around so they happen at better times.
For example, measuring qubits as early as possible can reduce the maximum number of simultaneously stored qubits; potentially enabling an algorithm to be run on a smaller quantum computer or to be simulated more efficiently.
Alternatively, deferring all measurements until the end of circuits allows them to be analyzed using only pure states.
References
Quantum information science | Deferred measurement principle | [
"Physics"
] | 186 | [
"Quantum mechanics",
"Quantum physics stubs"
] |
42,727,311 | https://en.wikipedia.org/wiki/Omega%20Cancri | The Bayer designation ω Cancri (Omega Cancri) is shared by two stars in the constellation Cancer:
ω1 Cancri or 2 Cancri, commonly called simply ω Cancri.
ω2 Cancri or 4 Cancri.
References
Cancer (constellation)
Cancri, Omega | Omega Cancri | [
"Astronomy"
] | 65 | [
"Cancer (constellation)",
"Constellations"
] |
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