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47,507,984 | https://en.wikipedia.org/wiki/GIWS%20%28software%29 | GIWS is a wrapper generator intended to simplify calling Java from C or C++ by automatically generating the necessary JNI code.
GIWS is released under the CeCILL license.
Example
The following Java class does some simple computation.
package basic_example;
import java.lang.Math;
public class MyComplexClass{
public MyComplexClass(){
// the constructor
}
public long myVeryComplexComputation(double a, double b){
return Math.round(Math.cos(a)+Math.sin(b)*9);
}
}
GIWS gives the capability to call it from C++.
#include <iostream>
#include "basic_example.hxx"
#include <jni.h>
JavaVM* create_vm() {
JavaVM* jvm;
JNIEnv* env;
JavaVMInitArgs args;
JavaVMOption options[2];
args.version = JNI_VERSION_1_4;
args.nOptions = 2;
options[0].optionString = const_cast<char*>("-Djava.class.path=.");
options[1].optionString = const_cast<char*>("-Xcheck:jni");
args.options = options;
args.ignoreUnrecognized = JNI_FALSE;
JNI_CreateJavaVM(&jvm, (void **)&env, &args);
return jvm;
}
using namespace basic_example;
using namespace std;
int main(){
JavaVM* jvm = create_vm();
MyComplexClass *testOfMyClass = new MyComplexClass(jvm);
cout << "My Computation: " << testOfMyClass->myVeryComplexComputation(1.2,80) << endl;
return 0;
}
To generate the binding, GIWS uses a XML declaration. GIWS will generate the JNI code to call the Java object.
<package name="basic_example">
<object name="MyComplexClass">
<method name="myVeryComplexComputation" returnType="long">
<param type="double" name="a" />
<param type="double" name="b" />
</method>
</object>
</package>
See also
SWIG allows one to call C or C++ from higher level languages
References
External links
Programming tools
Cross-platform software
Free computer programming tools
Java platform | GIWS (software) | [
"Technology"
] | 580 | [
"Computing platforms",
"Java platform"
] |
62,977,003 | https://en.wikipedia.org/wiki/NGC%20920 | NGC 920 is a barred spiral galaxy in the Andromeda constellation. The celestial object was discovered on September 11, 1885 by the American astronomer Lewis A. Swift.
See also
List of NGC objects (1–1000)
References
External links
Barred spiral galaxies
920
Andromeda (constellation)
009377 | NGC 920 | [
"Astronomy"
] | 65 | [
"Andromeda (constellation)",
"Constellations"
] |
62,977,815 | https://en.wikipedia.org/wiki/Twilight%20switch | A twilight switch is an electronic component that allows the automatic activation of a lighting circuit when natural light drops in a given environment. Among a large number of uses, the most common is to enable automatic lighting of streets, roads, highways, roads, gardens, courtyards, etc., when sunlight drops below a certain level (e.g.: a from twilight).
A circuit built with a twilight switch, in some cases, requires other components, such as relays or contactors, when you want to control a higher electrical power (lamps, electrical appliances, etc.).
Technical characteristics
By means of a light intensity sensor ( photoresistor, photodiode, phototransistor, etc.) that detects the amount of light that illuminates an environment, it triggers an electrical circuit that opens or closes the contacts of a mechanical relay or of a solid state relay. (power transistor, thyristor, triac, etc.), which activates the lighting system. Generally, the natural lighting that goes directly to a photoresistor is used, with the effect of a lamp that automatically turns on at dusk and always goes out in the first light of dawn. Thanks to this system, a wide range of examples of use are created, from lighting both public and private spaces to the simulation of presence, where the twilight switch provides the intermittent operation of a circuit. lighting to simulate the presence of people who are not physically present.
There are more and more innovative models that allow greater sensitivity to sunlight, with which you can adjust the threshold so that the switch fires at a certain level of darkness, thus setting a delay on and off with respect to the ambient light level. There are even models that do not turn on artificial light and distinguish it from natural light, although in some cases it may be convenient to combine them with time scheduling systems.
Electromechanical sensor
The most commonly used twilight switches are of the electromechanical type, which differ from electronic ones by the use of piloted relays already integrated in the circuit itself, and which allow small loads to be directly connected (for example, a single lamp). Twilight switches are available in various shapes to suit every need. In fact, they can vary from the shape of a lamp holder to that of a separate box (cylindrical, square, etc.).
Pay attention to the number of lamps that power the device and its power in watts, following the instructions in the user manual, in order to avoid a dangerous current overload on the contacts of the drive relay, in fact, if higher loads are required, a contactor will need to be inserted. For street lighting, for example, an individual twilight switch can be used, or a central switch that activates the other remote relays to turn on many lamps, so that the load that the central twilight switch must withstand is only of the individual coils of the relays in parallel.
Advantages
The main benefit of using a twilight switch is the considerable energy savings it brings, combined with the convenience of unnecessary time scheduling, which effectively regulates sunlight.
Disadvantages
The major downside to doing the installation is that if you place artificial light near a photo-sensitive detector, the switch may not turn on. In this case you have to be careful where the light bulbs are located with respect to the photodetectors. Also, keep in mind that ignition is based solely on the amount of natural light present and not on the height of the sun, so "unwanted ignition" may occur, for example in the presence of compact clouds associated with a significant drop in ambient light on the sensor (e.g., when there is a storm). To avoid this, twilight switches can be combined with time scheduling systems.
References
Bibliography
Helmut Röder, Heinz Ruckriegel, Heinz Häberle: Elektronik 1.Teil, Grundlagen Elektronik. 8. Auflage, Verlag Europa-Lehrmittel, Wuppertal, 1980,
Wilhelm Gerster: Moderne Beleuchtungssysteme für drinnen und draussen. 1. Auflage, Compact Verlag, München, 1997,
See also
Timer
Staircase timer
Motion sensor
Home automation | Twilight switch | [
"Technology"
] | 861 | [
"Home automation"
] |
62,978,769 | https://en.wikipedia.org/wiki/Penis%20extender | A penis extender is an external medical device with tentative evidence as of 2019 for Peyronie's disease. It acts as a mechanical, traction device that stretches the human penis in the flaccid state to make it longer.
Description
Penis extenders usually have a plastic ring that sits at the base of a flaccid penis, and another ring before the glans penis, with a traction device that runs along the sides of the organ. The wearer adjusts springs, which pull the penile shaft with the intention of stretching the flaccid penis to become longer.
Medical use
There is tentative evidence for use in Peyronie's disease. As of 2019, studies have been small in size; many had difficulty carrying out the treatment during the study period, and people were not blinded to the treatment that they were receiving.
Adverse effects
Adverse effects are not extensively reported in the literature, and they are usually mild and self-limiting, in part caused by lack of patient compliance with penile traction therapy (PTT). The most commonly reported symptoms with PTT include pain, erythema, ecchymoses, and pruritus. Another reported symptom was edema to the pubic bone, which is associated with vigorous usage. All of these adverse events are generally self-limited and resolve with discontinuation of PTT. Seek advice on how to use the penis extender safely, and correctly.
It should not be used if penile wounds, lacerations, or infected zones have not fully healed, and by those suffering certain diseases or disorders. Aggressive or incorrect uses of penis extenders can cause damage to skin and blood vessels, among other possible issues.
See also
Body dysmorphic disorder
Erectile dysfunction
Erection
Human penis size
Micropenis
Penis enlargement
References
Bibliography
Further reading
External links
Medical devices
Penis
Urology | Penis extender | [
"Biology"
] | 383 | [
"Medical devices",
"Medical technology"
] |
62,978,872 | https://en.wikipedia.org/wiki/Climate%20Clock | The Climate Clock is a graphic to demonstrate how quickly the planet is approaching 1.5 °C of global warming, given current emissions trends. It also shows the amount of CO2 already emitted, and the global warming to date.
PP Climate Clock was launched in 2015 to provide a measuring stick against which viewers can track climate change mitigation progress. The date shown when humanity reaches 1.5 °C will move closer as emissions rise, and further away as emissions decrease. An alternative view projects the time remaining to 2.0 °C of warming. The clock is updated every year to reflect the latest global CO2 emissions trend and rate of climate warming. On September 20, 2021, the clock was delayed to July 28, 2028, likely because of the COP26 Conference and the land protection by indigenous peoples. As of April 2, 2024, the clock counts down to July 21, 2029 at 12:00 PM.
The clock is hosted by Human Impact Lab, itself part of Concordia University. Organisations supporting the climate clock include Concordia University, the David Suzuki Foundation, Future Earth, and the Climate Reality Project.
As of April 29, 2024, the current climate temperature is 1.297 °C.
Relevance
1.5 °C is an important threshold for many climate impacts, as shown by the Special Report on Global Warming of 1.5 °C. Every increment to global temperature is expected to increase weather extremes, such as heat waves and extreme precipitation events. There is also the risk of irreversible ice sheet loss. Consequent sea level rise also increases sharply around 1.75 °C, and virtually all corals could be wiped out at 2 °C warming.
The New York Climate Clock
In late September 2020, artists and activists, Gan Golan, Katie Peyton Hofstadter, Adrian Carpenter and Andrew Boyd repurposed the Metronome in Union Square in New York City to show the Climate Clock. The goal was to "remind the world every day just how perilously close we are to the brink." This is in juxtaposition to the Doomsday Clock, which measures a variety of factors that could lead to "destroying the world" using "dangerous technologies of our making," with climate change being one of the smaller factors. This specific installation is expected to be one of many in cities around the world. At the time of installation, the clock read 7 years and 102 days. Greta Thunberg, Swedish environmental activist, was involved in the project early on, and reportedly received a hand-held version of the climate clock.
Since its inception, the New York Climate Clock has added a second set of numbers for the percentage of the world's energy use that comes from renewable energy sources.
See also
Climate Action Tracker
Doomsday Clock
Paris Agreement: limits global warming to 2 °C, pursues 1.5 °C
Effects of global warming which further increase CO2 emissions: forest fires, arctic methane release, ...
References
External links
Climate Clock website
Another climate clock
Climate Action Tracker: continuously tracks emissions of individual countries
Alert measurement systems
Clocks
Political symbols | Climate Clock | [
"Physics",
"Technology",
"Engineering"
] | 624 | [
"Machines",
"Clocks",
"Alert measurement systems",
"Measuring instruments",
"Physical systems",
"Warning systems"
] |
62,979,332 | https://en.wikipedia.org/wiki/Windows%20Open%20Services%20Architecture | Windows Open Services Architecture (WOSA) is a set of proprietary Microsoft technologies intended to "...provide a single, open-ended interface to enterprise computing environments.". WOSA was announced by Microsoft in 1992. WOSA was pitched as a set of programming interfaces designed to provide application interoperability across the Windows environment.
The set of technologies that were part of he WOSA initiative include:
LSAPI (Software Licensing API)
MAPI (Mail Application Programming Interface)
ODBC (Open Database Connectivity)
OLE for Process Control
SAPI (Speech Application Programming Interface)
TAPI (Telephony Application Programming Interface)
Windows SNA (IBM SNA Networks)
WOSA/XFS (WOSA for Financial Services)
WOSA/XRT (WOSA for Real-time Market Data)
See also
Component Object Model
Object Linking and Embedding
References
External links
Inter-process communication
Windows communication and services
Architectural pattern (computer science)
Enterprise application integration
Service-oriented (business computing)
Web services
Component-based software engineering | Windows Open Services Architecture | [
"Technology"
] | 210 | [
"Component-based software engineering",
"Components"
] |
62,979,819 | https://en.wikipedia.org/wiki/Radiant%20Mercury | Radiant Mercury is a cross-domain solution (CDS) software application developed by Lockheed Martin primarily in use by the US Navy.
As a CDS, it is designed to allow communications between higher-level classified networks and lower-level, unclassified networks.
See also
Guard (information security)
References
Computer security software
Lockheed Martin | Radiant Mercury | [
"Engineering"
] | 66 | [
"Cybersecurity engineering",
"Computer security software"
] |
62,980,659 | https://en.wikipedia.org/wiki/GGSE-4 | The Gravity Gradient Stabilization Experiment (GGSE-4) was a technology satellite launched in 1967. This was ostensibly the fourth in a series that developed designs and deployment techniques later applied to the NOSS/Whitecloud reconnaissance satellites.
History
GGSE-4 was launched by the U.S. Airforce from Vandenberg Air Force Base atop a Thor Agena-D rocket.
GGSE-4 remained operational from 1967 through 1972.
It is alleged that the real name of GGSE-4 was POPPY 5B or POPPY 5b and that it was a U.S. National Reconnaissance Office satellite designed to collect signals intelligence; POPPY 5B was part of a 7-satellite mission. A partial subset of information about POPPY was declassified in 2005.
Other sources say that GGSE-4 weighed only 10 pounds but that it was attached to the much larger Poppy 5, which would have weighed 85 kg and featured an 18-meter boom.
It is further alleged that GGSE-4's mass is not at all like GGSE-1's mass and that GGSE'4 weighs 85 kg.
2020 near-miss
On , GGSE-4 was expected to pass as closely as 12 meters from IRAS, another un-deorbited satellite left aloft. IRAS was launched in 1983 and abandoned after a 10-month mission. The 14.7-kilometer per second pass had an estimated risk of collision of 5%. Further complications arose from the fact that GGSE-4 was outfitted with an 18 meter long stabilization boom that was in an unknown orientation and may have struck the satellite even if the spacecraft's main body did not. Initial observations from amateur astronomers seemed to indicate that both satellites had survived the pass, with the California-based debris tracking organization LeoLabs later confirming that they had detected no new tracked debris following the incident.
See also
Gravity Gradient Stabilization Experiment (GGSE-1)
References
Space | GGSE-4 | [
"Physics",
"Mathematics"
] | 405 | [
"Spacetime",
"Space",
"Geometry"
] |
62,983,097 | https://en.wikipedia.org/wiki/NGC%203656 | NGC 3656 is a peculiar galaxy formed by the collision of two galaxies in the constellation of Ursa Major. It is located about 135 million light years away from Earth, which means, given its apparent dimensions, that NGC 3656 is approximately 70,000 light years across. It was discovered by William Herschel on April 14, 1789.
Characteristics
NGC 3656 is a galaxy merger, created by the collision of two disk galaxies. The merger has created shells around the galaxy and two faint tidal tails. The first tail emanates from a position angle of 260° and after bends to the north-northwest. Its total extent is about 180 arcseconds, towards a dwarf galaxy, and maybe even more, towards a second dwarf galaxy. Its width is 15 arcseconds. The other tail lies at the north-northeast part of the galaxy and is not as well defined as the other. Other characteristics of the galaxy include the presence of a condensation at the south part of the galaxy connected with the rest of the galaxy with a ring-like feature and is associated with a bright shell.
A prominent feature of the galaxy is a dark lane running across the minor axis of the galaxy, similar to that observed in Centaurus A. At the centre of the galaxy a warped molecular gas disk extending for about 7 kiloparsecs has been observed in H I imaging, with an estimated mass of . The inner part of the disk features more intense star formation. The total star formation rate of the galaxy is estimated to be 1.1 per year.
The nucleus of NGC 3656 has been found to rotate around an axis that is almost perpendicular to the rotation axis of the rest of the galaxy, which is another indication of a galaxy merger.
Supernovae
Two supernovae have been observed in NGC 3656:
SN 1963K (type unknown, mag. 15) was discovered by Charles Bertaud on 15 June 1963.
SN 1973C (type unknown, mag. 17) was discovered by Charles Kowal on 11 January 1973. It was co-discovered by Shakhbazyan.
Nearby galaxies
NGC 3656 is the foremost member in a galaxy group known as the NGC 3656 group. Another member is UGC 6422. A bit further away lies the galaxy NGC 3549 with its group. Five dwarf galaxies with estimated masses between and have been detected in HI imaging around the galaxy and are probably in the process of being accreted by NGC 3656.
See also
List of NGC objects (3001–4000)
References
External links
NGC 3656 on SIMBAD
Irregular galaxies
Ring galaxies
Peculiar galaxies
Galaxy mergers
Ursa Major
Discoveries by William Herschel
Astronomical objects discovered in 1789
3656
06403
34989
155 | NGC 3656 | [
"Astronomy"
] | 555 | [
"Ursa Major",
"Constellations"
] |
62,983,169 | https://en.wikipedia.org/wiki/Chrome%20Azurol%20S | Chrome Azurol S is a histological dye used in biomedical research.
Chrome Azural S (CAS) is a common spectrophotometric reagent for detection of certain metals like aluminum which can be toxic in excess and can contribute to people with neurodegenerative disorders. CAS is used to provide quantitative and qualitative information on molecules of interest like aluminum and siderophores. Qualitatively a color change can be observed while also allowing to quantitatively determine concentration of certain ions.
References
Staining dyes | Chrome Azurol S | [
"Chemistry",
"Biology"
] | 112 | [
"Biochemistry stubs",
"Biotechnology stubs",
"Biochemistry"
] |
62,983,576 | https://en.wikipedia.org/wiki/Fluorite%20structure | The fluorite structure refers to a common motif for compounds with the formula MX2. The X ions occupy the eight tetrahedral interstitial sites whereas M ions occupy the regular sites of a face-centered cubic (FCC) structure. Many compounds, notably the common mineral fluorite (CaF2), adopt this structure.
Many compounds with formula M2X have an antifluorite structure. In these the locations of the anions and cations are reversed relative to fluorite (an anti-structure); the anions occupy the FCC regular sites whereas the cations occupy the tetrahedral interstitial sites. For example, magnesium silicide, Mg2Si, has a lattice parameter of 6.338 Å with magnesium cations occupying the tetrahedral interstitial sites, in which each silicide anion is surrounded by eight magnesium cations and each magnesium cation is surrounded by four silicide anions in a tetrahedral fashion.
Calcium fluoride example
Crystallography is a powerful tool to investigate the structures of crystalline materials. It is important to understand the crystal structure of materials to form structure-property relationships. These relationships can help predict the behavior of crystalline materials, as well as introduce the ability to tune their properties. Calcium fluoride is a classic example of a crystal with a fluorite structure. Crystallographic information can be collected via x-ray diffraction, providing information on the locations of electron density within a crystal structure. Using modern software such as Olex2, one can solve a crystal structure from crystallographic output files.
Views of calcium fluoride crystal structure
In calcium fluoride, the calcium cations are surrounded by fluorine anions that occupy the tetrahedral sites, with an 8:4 coordination number, fluorine to calcium. This ratio is consistent with the stoichiometry of the compound, where the ratio of fluorine to calcium is 2:1. This relationship can be visualized as a cubic array of anions surrounding the calcium cations.
Extended fluorite structure
Beyond the until cell, the extended crystal structure of fluorite continues packing in a face-centered cubic (fcc) packing structure (also known as cubic close-packed or ccp). This pattern of spherical packing follows an ABC pattern, where each successive layer of spheres settles on top of the adjacent hole of the lattice. In contrast, hexagonal close-packed (hcp), are successively layered with an ABAB pattern. These two types of packing are the most closely packed forms of spherical packing.
See also
Rock-salt structure
References
Cubic minerals
Minerals in space group 225
Fluorine minerals
Crystal structure types | Fluorite structure | [
"Chemistry",
"Materials_science"
] | 555 | [
"Crystallography",
"Crystal structure types"
] |
62,985,630 | https://en.wikipedia.org/wiki/Chinese%20Materials%20Research%20Society | The Chinese Materials Research Society (; abbreviated C-MRS) is a professional body and learned society in the field of materials science and engineering in China, founded on May 16, 1991. As of 2019, the society has 9 subordinate working committees, 22 branches, 184 unit members and more than 8,000 individual members. It is a constituent of the China Association for Science and Technology (CAST) and a member of the International Union of Materials Research Society (IUMRS). The society provides forums for the exchange of information. It aims at promoting the research and development of all kinds of advanced materials, and striving to promote the practical application of new materials, new processes and new technologies in the industry.
Scientific publishing
Progress in Natural Science: Materials International (PROG NAT SCI-MATER)
References
External links
Materials science organizations
Scientific organizations established in 1991
Organizations based in Beijing
1991 establishments in China
1991 in Beijing | Chinese Materials Research Society | [
"Materials_science",
"Engineering"
] | 184 | [
"Materials science organizations",
"Materials science"
] |
62,985,895 | https://en.wikipedia.org/wiki/Power-off%20accuracy%20approach | A power-off accuracy approach, also known as a glide approach, is an aviation exercise used to simulate a landing with an engine failure. The purpose of this training technique is to better develop one's ability to estimate distance and glide ratios. The variation in each angle refers to the degrees an aircraft must turn to be aligned with the runway. Consideration of the wind and use of flaps are important factors in executing power-off accuracy approaches.
When the throttle is closed, it is intended to simulate engine failure.
Iterations of power-off approaches
90° power-off
A 90° approach calls for the throttle to be closed when the aircraft is angled 45° from centerline. On Base leg, the airspeed needs to be lowered to the manufacturer's recommended glide speed. In order to stretch the gliding distance, pilots will often pitch up momentarily to attain best glide speed, also known as Vg. Once this speed is reached, the nose of the plane is slightly lowered to maintain the current airspeed. When turning final, if the pilot justifies that the plane is above the glide path and altitude must be lost, flaps can be used as needed.
Depending on the strength of the wind, the pilot will adjust the base leg to be closer or further away from the runway's approach end. Stronger winds tend to result in the closest base, while weaker winds allow for a closer to normal traffic pattern.
180° power-off
This variation is an extension of the 90° approach. For the Power-Off 180, on the Downwind leg, the pilot pulls the power to idle when abeam the intended landing point. Immediately following throttle to idle, the plane is pitched to Vg, which is the best glide speed determined by the manufacturer. At this point, the pilot now judges the gliding distance and determines an appropriate time to turn base. When approaching final, the pilot should have a general idea if they are above or below the glide path, which will in turn affect their use of flaps or a Forward Slip.
This maneuver is part of the United States Department of Transportation, Federal Aviation Administration (FAA) Commercial Pilot – Airplane Airmen Certification Standards. According to the FAA, completion of this standard demonstrates a pilot's ability to:
360° power-off
The 360° Power-off approach requires the plane to glide in a circular pattern, starting 2,000 ft or more, above the intended landing point. When the aircraft is positioned over the landing point, the throttle is closed and again, the proper glide speed must be attained. After establishing the appropriate speed, the pilot can safely steer the plane using medium turns to approach downwind leg. The plane should be around 1,000 to 1,200 ft above the ground at the spot where the plane is parallel to the intended point of landing, in relation to downwind leg. When arriving at base leg position, the plane should be around 800 ft above the terrain.
Factors
Wind
Wind plays a crucial role in Power-off accuracy maneuvers. If pilots fail to take into account the wind, the performance and accuracy of the maneuver becomes swayed.
Flaps
In each of the power-off accuracy approaches, flaps are a mechanism that can be used to assist in performing the maneuver. Stalling speed is reduced and drag is increased when flaps are extended. This allows for a steeper and slower approach. However, depending on weather conditions or other circumstances, such as prolonged extension of downwind or base leg, use of flaps may not be required.
Common errors
The Airplane Flying Handbook of the Federal Aviation Administration lists common mistakes pilots make when performing power-off accuracy approaches. A few of these errors are listed below.
Force landing to avoid overshooting designated landing spot
Extending flaps and/or gears prematurely
Downwind leg too far from the runway
Poor compensation of wind drift
Overextension of downwind leg
See also
Turbine engine failure
References
Flight training
Powered flight
Emergency aircraft operations | Power-off accuracy approach | [
"Physics"
] | 788 | [
"Power (physics)",
"Powered flight",
"Physical quantities"
] |
62,986,086 | https://en.wikipedia.org/wiki/Chinese%20Ceramic%20Society | The Chinese Ceramic Society (; abbreviated CCS) of Beijing is a Chinese non-profit professional body and learned society in the field of Chinese ceramics with a focus on scientific research, emerging technologies, and applications in which ceramic materials are an element.
History
The Chinese Ceramic Society started in 1945 as a research group in southwest China's Chongqing city. In January 1951 this group became the "China Kiln Engineering Society" (), but was closed down in October. In December 1956, the "Preparatory Committee of China Silicates Society" () was founded in Beijing, and in November 1959 the name was changed to the "Chinese Ceramic Society". As of 2018, the society has 21 specialized committees and 3 working committees with more than 20,000 individual members.
Scientific publishing
Journal of Materiomics
References
External links
Zirconia Ceramic
Ceramic materials
Ceramic engineering
1945 in Beijing
Glass engineering and science
Materials science organizations
Scientific organizations established in 1945
Organizations based in Beijing
1945 establishments in China | Chinese Ceramic Society | [
"Materials_science",
"Engineering"
] | 199 | [
"Glass engineering and science",
"Materials science",
"Materials science organizations",
"Ceramic materials",
"Ceramic engineering"
] |
62,986,341 | https://en.wikipedia.org/wiki/Cold%20start%20%28computing%29 | Cold start in computing refers to a problem where a system or its part was created or restarted and is not working at its normal operation. The problem can be related to initialising internal objects or populating cache or starting up subsystems.
In a typical web service system the problem occurs after restarting the server, and also when clearing the cache (e.g., after releasing new version). The first requests to the web service will cause significantly more load due to the server cache being populated, the browser cache being cleared, and new resources being requested. Other services like a caching proxy or web accelerator will also need time to gather new resources and operate normally.
Similar problem occurs when creating instances in a hosted environment and instances in cloud computing services.
Cold start (or cold boot) may also refer to a booting process of a single computer (or virtual machine). In this case services and other startup applications are executed after reboot. The system is typically made available to the user even though startup operations are still performed and slow down other operations.
Another type of problem is when the data model of a particular system requires connections between objects. In that case new objects will not operate normally until those connections are made. This is well known problem with recommender systems.
In some machine learning scenarios, with models where the training dataset is incrementally added to in time (e.g. in active learning), cold start refers to training the model on the so far obtained labeled pool with new data added de novo, instead of training the model on new data with all its knowledge from previous trainings (warm start). Unlike the previous mentioned instances, cold starting in these scenarios can yield better results of the model.
See also
Cold start (recommender systems)
References
Information systems | Cold start (computing) | [
"Technology"
] | 362 | [
"Information systems",
"Information technology"
] |
73,026,681 | https://en.wikipedia.org/wiki/Astronomers%20Monument | The Astronomers Monument in front of Griffith Observatory in Los Angeles, California is a New Deal artwork created under the auspices of the Public Works of Art Project. The large outdoor concrete sculpture honors the work of six great astronomers and is a Griffith Park landmark in its own right.
History and design
The Astronomers Monument pays homage to six of the greatest astronomers of all time: Hipparchus (), Nicolaus Copernicus (1473–1543), Galileo Galilei (1564–1642), Johannes Kepler (1571–1630), Isaac Newton (1642–1727), and William Herschel (1738–1822).
In December 1933, the Los Angeles Park Commission and the Public Works of Art Project (PWAP) commissioned a sculpture project for the grounds of the under-construction Griffith Observatory. Using a design by local artist Archibald Garner and materials donated by the Women's Auxiliary of the Los Angeles Chamber of Commerce, six artistsGarner, Roger Noble Burnham (creator of USC's Tommy Trojan), Djey El Djey (1905-1980, real name Djey Owens), Gordon Newell (1905–1998), George Stanley (creator of the famous Oscar statuette presented at the Academy Awards), and Arnold Foerster (1878–1943)sculpted and cast the concrete monument and figures. Each artist was responsible for sculpting one astronomer: Stanley did Newton, Garner sculpted Copernicus, Newell was responsible for Kepler, etc. (Burnham may have created the depiction of Herschel; the authorship of the Hipparchus and Galileo figures is unclear.)
According to the Los Angeles Times art critic Arthur Millier in 1934, the "original idea" was Foerster's, and he was "responsible for the delicate engineering entailed in pouring a forty-foot concrete shaft." The monument is topped with an armillary sphere, originally concrete, replaced with a bronze piece in 1991.
On November 25, 1934, almost six months prior to the opening of the Observatory on May 14, 1935, a celebration took place to mark completion of the Astronomers Monument. The only "signature" on the Astronomers Monument is "PWAP 1934," referring to the program which funded the project and the year in which it was completed.
See also
List of New Deal sculpture
List of public art in Los Angeles
Isaac Newton in popular culture
Santa Monica, another large cast-concrete PWAP sculpture in Los Angeles County
References
1934 sculptures
1934 establishments in California
Concrete sculptures in California
Outdoor sculptures in Greater Los Angeles
Griffith Park
Public Works of Art Project
Cultural depictions of Nicolaus Copernicus
Cultural depictions of Galileo Galilei
Cultural depictions of Johannes Kepler
Cultural depictions of Isaac Newton | Astronomers Monument | [
"Astronomy"
] | 547 | [
"Cultural depictions of Galileo Galilei",
"Cultural depictions of astronomers",
"Cultural depictions of Nicolaus Copernicus",
"Cultural depictions of Isaac Newton",
"Cultural depictions of Johannes Kepler"
] |
73,027,829 | https://en.wikipedia.org/wiki/Inverter-based%20resource | An inverter-based resource (IBR) is a source of electricity that is asynchronously connected to the electrical grid via an electronic power converter ("inverter"). The devices in this category, also known as converter interfaced generation (CIG), include the variable renewable energy generators (wind, solar) and battery storage power stations. These devices lack the intrinsic behaviors (like the inertial response of a synchronous generator) and their features are almost entirely defined by the control algorithms, presenting specific challenges to system stability as their penetration increases, for example, a single software fault can affect all devices of a certain type in a contingency (cf. section on Blue Cut fire below). IBRs are sometimes called non-synchronous generators. The design of inverters for the IBR generally follows the IEEE 1547 and NERC PRC-024-2 standards.
Grid-following vs. grid-forming
A grid-following (GFL) device is synchronized to the local grid voltage and injects an electric current vector aligned with the voltage (in other words, behaves like a current source). The GFL inverters are built into an overwhelming majority of installed IBR devices. Due to their following nature, the GFL device will shut down if a large voltage/frequency disturbance is observed. The GFL devices cannot contribute to the grid strength, dampen active power oscillations, or provide inertia.
A grid-forming (GFM) device partially mimics the behavior of a synchronous generator: its voltage is controlled by a free-running oscillator that slows down when more energy is withdrawn from the device. Unlike a conventional generator, the GFM device has no overcurrent capacity and thus will react very differently in the short-circuit situation. Adding the GFM capability to a GFL device is not expensive in terms of components, but affects the revenues: in order to support the grid stability by providing extra power when needed, the power semiconductors need to be oversized and energy storage added. Modeling demonstrates, however, that it is possible to run a power system that almost entirely is based on the GFL devices. A combination of GFM battery storage power station and synchronous condensers (SuperFACTS) is being researched.
Features
Compliance with IEEE 1547 standard makes the IBR to support safety features:
if the sensed line voltage significantly deviates from the nominal (usually outside the limits of 0.9 to 1.1 pu), the IBR shall disconnect from the after a delay (so called ridethrough time), the delay is shorter if the voltage deviation is larger. Once the inverter is off, it will stay disconnected for a significant time (minutes);
if the voltage magnitude is unexpected, the inverter shall enter the momentary cessation state: while still connected, it will not inject any power into the grid. This state has a short duration (less than a second).
Once an IBR ceases to provide power, it can come back only gradually, ramping its output from zero to full power.
The electronic nature of IBRs limits their overload capability: the thermal stress causes their components to even temporarily be able to function at no more than 1-2 times the nameplate capacity, while the synchronous machines can briefly tolerate an overload as high as 5-6 times their rated power.
Vulnerabilities
New challenges to the system stability came with the increased penetration of IBRs. Incidences of disconnections during contingency events where the fault ride through was expected, and poor damping of subsynchronous oscillations in weak grids were reported.
One of the most studied major power contingencies that involved IBRs is the Blue Cut Fire of 2016 in Southern California, with a temporary loss of more than a gigawatt of photovoltaic power in a very short time.
Blue Cut fire
The Blue Cut fire in the Cajon Pass on August 16, 2016, has affected multiple high-voltage (500 kV and 287 kV) power transmission lines passing through the canyon. Throughout the day thirteen 500 kV line faults and two 287 kV faults were recorded. The faults themselves were transitory and self-cleared in a short time (2-3.5 cycles, less than 60 milliseconds), but the unexpected features of the algorithms in the photovoltaic inverter software triggered multiple massive losses of power, with the largest one of almost 1,200 megawatts at 11:45:16 AM, persisting for multiple minutes.
The analysis performed by the North American Electric Reliability Corporation (NERC) had shown that:
700 MW of loss were caused by the poorly designed frequency estimation algorithm. The line faults had distorted the AC waveform and fooled the software into a wrong estimate of the grid frequency dropping below 57 Hz, a threshold where an emergency disconnect shall be initiated. However, the actual frequency during the event had never dropped below 59.867 Hz, well above the low limit of the normal frequency range (59.5 Hz for the Western Interconnection).
Additional 450 MW were lost when low line voltage caused the inverters to immediately cease to inject current, with gradual return to operative state within 2 minutes. At least one manufacturer had indicated that injecting the current when the voltage level is below 0.9 pu would involve a major redesign.
As a result of the incident, NERC had issued multiple recommendations, involving the changes in inverter design and amendments to the standards.
References
Sources
Electrical engineering | Inverter-based resource | [
"Engineering"
] | 1,169 | [
"Electrical engineering"
] |
73,027,987 | https://en.wikipedia.org/wiki/Piecewise%20algebraic%20space | In mathematics, a piecewise algebraic space is a generalization of a semialgebraic set, introduced by Maxim Kontsevich and Yan Soibelman. The motivation was for the proof of Deligne's conjecture on Hochschild cohomology. Robert Hardt, Pascal Lambrechts, Victor Turchin, and Ismar Volić later developed the theory.
References
Maxim Kontsevich and Yan Soibelman. “Deformations of algebras over operads and the Deligne conjecture”. In: Conférence Moshé Flato 1999, Vol. I (Dijon). Vol. 21. Math. Phys. Stud. Dordrecht: Kluwer Acad. Publ., 2000, pp. 255–307. arXiv: math/0001151.
Algebraic geometry | Piecewise algebraic space | [
"Mathematics"
] | 169 | [
"Fields of abstract algebra",
"Algebraic geometry",
"Geometry",
"Geometry stubs"
] |
73,028,040 | https://en.wikipedia.org/wiki/LDC%20Group | LDC (Lambert Dodard Chancereul) is the largest poultry meat group in Europe. LDC carries out 578 million animal slaughters per year. The total revenue amounted to €5.1 billion in 2021/22.
The company is headquartered in Sablé-sur-Sarthe in France and operates 93 production sites in five European countries.
History
The company was founded in 1968 as a merger of the family business Lambert based in Sablé-sur-Sarthe and Dodard-Chancereul based in Saint-Denis-d’Anjou. In 1970, the company expanded and opened a poultry slaughterhouse in Sablé-sur-Sarthe.
In the 1990s, LDC took over the convenience food company La Toque Angevine. In 1995, LDC went public at the Euronext Paris and conducted the first international takeover with Hermanos Saiz from Spain. Subsequently, the French company started an international expansion. Among others, the company took over the Polish company Drosed in 2000, the Hungarian Tranzit group in 2018, and the British poultry company Capestone Organic Poultry in 2021.
LDC also expanded in the French poultry farming and took over multiple competitors. In 2018, LDC took over parts of the insolvent Groupe Doux, and in 2022 the company Matines, one of the leading French egg producers, from the Avril group.
In 2022, LDC was struck by the historic outbreak of influenza A virus subtype H5N1 in France that lead to the culling of more than 12 million birds. The company had to shut down four slaughterhouses.
The executive management was passed from Denis Lambert to Philippe Gélin in 2022.
Structure
With more than 578 million animal slaughters per year, LDC is the largest poultry meat company in France and Europe. Further business areas are the production of pork, beef, rabbit meat and eggs.
The company is structure in the three divisions: Poultry, International and Catered-Food.
60% of the revenue is generated in France, where LDC has a share of 40% on the poultry market and 50% in the market for chilled delicatessen. The international revenue was generated to large parts in Poland (67%), followed by Hungary (22%), Belgium (6%) and the United Kingdom (4,5%). The company also serves the German market via the sites in Poland.
Sales
LDC markets its products under a number of brands, among others Le Gaulois, Maître Coq and Marie. LDC also supplies chicken to McDonald's.
Shareholders
Around 70% of the shares are owned by the families Lambert (39.2%), Chancereul (17.3%), Huttepain (8.86%) and Guillet (3.89%). Around 13% are in public float, the other shares belong to white-collar workers, to the Sofiprotéol group and to the cooperative Agricole Fermiers de Loué.
Controversies
After an analysis of chicken meat samples in 2020, Germanwatch criticized that 57% of the samples from LDC were contaminated and 45% of the samples were found featuring antimicrobial resistance against drugs of last resort.
References
External links
Official website
Food and drink companies established in 1968
French companies established in 1968
Poultry companies
Intensive farming
Meat companies of France
Companies based in Pays de la Loire
Companies listed on Euronext Paris | LDC Group | [
"Chemistry"
] | 699 | [
"Eutrophication",
"Intensive farming"
] |
73,028,060 | https://en.wikipedia.org/wiki/Deligne%27s%20conjecture%20on%20Hochschild%20cohomology | In deformation theory, a branch of mathematics, Deligne's conjecture is about the operadic structure on Hochschild cochain complex. Various proofs have been suggested by Dmitry Tamarkin, Alexander A. Voronov, James E. McClure and Jeffrey H. Smith, Maxim Kontsevich and Yan Soibelman, and others, after an initial input of construction of homotopy algebraic structures on the Hochschild complex. It is of importance in relation with string theory.
See also
Piecewise algebraic space
References
Further reading
https://ncatlab.org/nlab/show/Deligne+conjecture
https://mathoverflow.net/questions/374/delignes-conjecture-the-little-discs-operad-one
Algebraic topology
String theory
Conjectures | Deligne's conjecture on Hochschild cohomology | [
"Astronomy",
"Mathematics"
] | 171 | [
"Astronomical hypotheses",
"Unsolved problems in mathematics",
"Algebraic topology",
"Conjectures",
"Topology",
"Fields of abstract algebra",
"String theory",
"Mathematical problems"
] |
73,028,554 | https://en.wikipedia.org/wiki/Loyal%20wingman | A loyal wingman is a proposed type of unmanned combat air vehicle (UCAV) which incorporates artificial intelligence (AI) and is capable of collaborating with the next generation of crewed combat aircraft, including sixth-generation fighters and bombers such as the Northrop Grumman B-21 Raider. Also unlike the conventional UCAV, the loyal wingman[sic] is expected to be capable of surviving on the battlefield but to be significantly lower-cost than a crewed aircraft with similar capabilities. In the US, the concept is known as the collaborative combat aircraft (CCA).
Characteristics
The loyal wingman is a military drone with an onboard AI control system and capability to carry and deliver a significant military weapons load. The AI system is envisaged as being significantly lighter and lower-cost than a human pilot with their associated life support systems, but to offer comparable capability in flying the aircraft and in mission execution.
Some concepts are based on a standardised aircraft deployed in two variants; one as a sixth-generation fighter with a human pilot and/or battle commander in the cockpit, and the other as a loyal wingman with an AI system substituted in the same location. BAE Systems envisage the Tempest to be capable of operating in either configuration.
Another concept is to develop a shorter-range, and hence smaller and cheaper, wingman to be carried by the manned parent aircraft and air-launched when needed. The drone in turn carries its own munitions. This reduces the overall cost while maintaining protection for the crewed aircraft on the battlefield.
Role
The principal application is to elevate the role of human pilots to mission commanders, leaving AIs as "loyal wingmen" to operate under their tactical control as high-skill operators of relatively low-cost robotic craft.
Loyal wingmen can perform other missions as well, as "a sensor, as a shooter, as a weapons carrier, as a cost reducer".
Capabilities
A loyal wingman is expected to cost significantly less than a crewed fighter, and will typically be considered vulnerable to attrition. It would have sufficient intelligence and onboard defence systems to survive on the battlefield. The United States Secretary of the Air Force Frank Kendall has described them as remotely controlled versions of targeting pods, electronic warfare pods or weapons carriers to provide additional sensors and munitions; to balance affordability and capability.
Development history
The concept of the loyal wingman arose in the early 2000s and, since then, countries such as Australia, China, Japan, Russia, the UK and the US have been researching and developing the necessary design criteria and technologies.
Australia
Boeing Australia is leading development of the MQ-28 Ghost Bat loyal wingman for the RAAF, with BAE Systems Australia providing much of the avionics. The MQ-28 was first flown in 2021 and since then, at least 8 aircraft have been built.
China
China has been studying the loyal wingman concept since at least 2019 and has shown off some concept airframes. However, although China already manufactures drones and has well-developed swarming technology, the planned level of autonomy or even AI for these systems are not known.
Germany
European aerospace manufacturer Airbus has proposed the Airbus wingman which is a loyal wingman aircraft. The aircraft would be an unmanned combat aerial vehicle (UCAV) which would accompany a Eurofighter Typhoon or other combat aircraft as a force multiplier.
India
The HAL CATS Warrior is an AI-enabled wingman drone under development by Hindustan Aeronautics Ltd. (HAL) for the proposed Combat Air Teaming System (CATS).
Japan
Japan announced a development programme for a loyal wingman drone in 2021, issuing the first round of funding in 2022. The drone is intended to be carried for deployment by a proposed F-X fighter, also under development.
Russia
Russian projects for wingman-class drones are thought to include the Sukhoi S-70 Okhotnik and the Kronshtadt Grom. However, although Russia already manufactured drones, the planned level of autonomy or even AI for these systems are not known.
South Korea
In addition to the production of the new generation fighter, KF-21, South Korea plans to develop several types of UCAVs as wingmen to team up with the manned fighter.
United Kingdom
The RAF in the UK has been developing the Loyal Wingman concept since 2015, with the Spirit Mosquito technology demonstrator flying in 2020. Programme funding was cancelled in June 2022 because the Ministry of Defence felt that it was better spent on less ambitious advances.
United States
Collaborative combat aircraft (CCA) is the official US Air Force designation for an autonomous combat drone, and is broadly equivalent to the loyal wingman.
The USAF Next Generation Air Dominance (NGAD) program was initiated in 2014. It includes the development of CCA. Up to five autonomous CCAs could operate with a manned fighter.
The Skyborg programme, going back at least to 2019, is developing the systems to operate wingman drones alongside advanced manned fighters. Of four contenders, the most public is the Kratos XQ-58A Valkyrie. The Air Force Research Laboratory (AFRL) will test their Skyborg manned-unmanned programs such as Autonomous Air Combat Operations (AACO), and DARPA will test its Air Combat Evolution (ACE) artificial intelligence program. The System for Autonomous Control of Simulation (SACS) software for human interface is being developed by Calspan.
In 2020, DARPA AlphaDogfight predicted that AI programs that fly fighter aircraft will overmatch human pilots.
Two alternative autonomous AI systems have been installed in a General Dynamics X-62 VISTA at the Air Force Test Pilot School. The two systems flew the aircraft in turn, on 9 December 2022. By 16 December 2022 the X-62 Vista had flown eight sorties using ACE, and six sorties using AACO, at a rate of two sorties per day.
The General Atomics Longshot is intended to be carried for deployment by the manned aircraft, and is air-launched when needed. This allows a shorter range for the drone, while maintaining advanced protection for the manned aircraft. DARPA adopted the General Dynamics design for its Longshot programme in 2022.
In 2022 Heather Penney identified five key elements for the proactive development of autonomous CCA, remote pilots of UAVs and pilots flying separately in manned aircraft (also called crewed-uncrewed teaming, or manned-unmanned teaming).
Create concepts that will maximize the strengths of both CCA and piloted aircraft working as a team.
Include operators in CCA development to ensure they understand how they will perform in the battlespace.
Warfighters must be able to depend on CCA autonomy.
Warfighters must have assured control over CCA in highly dynamic operations.
Human workloads must be manageable.
A typical CCA is estimated to cost between one-half and one-quarter as much as an $80 million F-35. US Air Force Secretary Frank Kendall is aiming for an initial fleet of 1,000 CCAs.
List of loyal wingman aircraft
Several loyal wingman aircraft are or have been under development.
Examples include:
Boeing MQ-28 Ghost Bat - 8 in testing (Block 1), planned entry into active service in 2025
General Dynamics X-62 VISTA - system development aircraft
HAL CATS Warrior - under development
Kratos XQ-58 Valkyrie - development prototype flying
Kronshtadt Grom ("Thunder") - under development
Spirit Mosquito - program cancelled
Sukhoi S-70 Okhotnik - proposed development with upgraded avionics
Airbus Wingman - proposed development
Northrop Grumman Model 437 - development prototype flying
See also
Index of aviation articles
References
Unmanned military aircraft
Robotics
Command and control | Loyal wingman | [
"Engineering"
] | 1,562 | [
"Robotics",
"Automation"
] |
73,030,588 | https://en.wikipedia.org/wiki/DV%20Piscium | DV Piscium is a triple star system in the equatorial constellation of Pisces, abbreviated DV Psc. It is an eclipsing binary variable of the RS Canum Venaticorum class. The pair have a combined apparent visual magnitude of 10.59, which is too faint to be visible with the naked eye. Based on parallax measurements, DV Piscium is located at a distance of 137.5 light years from the Sun. It is drifting closer with a radial velocity of −28 km/s.
In 1994, this target was found to show emission line features in the calcium H and K lines. It was classified as a K-type star with high proper motion in 1986. Data from the ROSAT satellite showed significant X-ray emission. In 1999, it was shown to be a near-contact eclipsing binary star system by R. M. Robb and associates, with an orbital period of 0.30855 days. The shape of the light curve suggested the presence of one or more star spots on the cooler component. A flare event was observed on November 22, 2008, indicative of a high level of magnetic activity.
Combining photometric results across several years demonstrated that the light curve is highly variable, with star spot activity on both components. This varied over time in quantity, size, and location. This is a detached binary system with the components in near contact at a separation of just two solar radii. As of 2007, the period of the system is decreasing over time at a rate of about . The primary component has 68% of the mass of the Sun and 73% of the Sun's radius; the cooler secondary has 47% of the mass and 52% of the radius of the Sun. Both components are slightly evolved main sequence stars. The system has an activity cycle estimated at .
Evidence from O–C diagrams suggests there is a third component to this system, orbiting the inner pair with a period of on an eccentric orbit. This body has less than 62% of the mass of the Sun.
References
Further reading
K-type main-sequence stars
RS Canum Venaticorum variables
Eclipsing binaries
Triple star systems
Pisces (constellation)
Piscium, DV | DV Piscium | [
"Astronomy"
] | 458 | [
"Pisces (constellation)",
"Constellations"
] |
73,031,196 | https://en.wikipedia.org/wiki/Bellow%20%28sound%29 | Bellow /ˈbel.oʊ/ () is a type of animal vocalization common amongst bulls and other large animals such as rhinoceros, bison, yak, and red deer. It's a form of roaring and reverberating sound. Also, the bull snake bellows and hisses as its defensive sounds, It bellows at first in a short period high amplitude, followed by a longer period of low amplitude before it maintains a constant sound.
Bugles are also a form of vocalization in cattle, except that it is of high frequency while bellows are of low frequency measured in Hertz (Hz). The frequency of bellows and bugles depends on factors such as gender, species of cattle, and environment, with many anatomical patterns in the vocal production of the sounds.
In cows
Another sound a cow makes is mooing, and they do so to show anger, find other herds, and find their mates. Bulls also bellow to show contentment.
References
Animal sounds | Bellow (sound) | [
"Biology"
] | 207 | [
"Ethology",
"Behavior",
"Animal sounds"
] |
73,032,870 | https://en.wikipedia.org/wiki/Samira%20Siahrostami | Samira Siahrostami () is an Iranian computational chemist who is an associate professor at the University of Calgary. She designs new materials for catalysis, and develops computer simulations to understand electrochemical reactions. She was awarded the 2023 Canadian Society for Chemistry Tom Zeigler Award.
Early life and education
Siahrostami grew up in Iran, where she completed her undergraduate and graduate degree in physical chemistry. She moved to the Technical University of Denmark for a postdoctoral position at the Center for Atomic-scale Material Design. After two years in Denmark, she joined Stanford University, where she worked with Jens Nørskov and started working on computational catalysis.
Research and career
Siahrostami joined the University of Calgary as an assistant professor in 2018, and was promoted to associate professor in 2022. Her research involves computational chemistry for the design of new catalyst materials. Specifically, she studies the oxygen reduction reaction and the carbon dioxide reduction reaction. The oxygen reduction reaction limits the efficiency of fuel cells. Siahrostami hopes that her simulations can provide insight about the active sites for oxygen reduction, helping to develop new, more efficient cathode materials. The carbon dioxide reduction reaction offers hope for carbon dioxide mitigation, as well as providing a new strategy to produce chemicals and fuels. Siahrostami makes use of carbon-based nanomaterials for carbon dioxide reduction reaction catalysis. Some of the catalysts that she has predicted computationally have since been commercialised.
Alongside reduction reactions, Siahrostami is interested in hydrogen: both the synthesis of hydrogen peroxide for water purification and the production of clean hydrogen.
Awards and honours
2021 Royal Society of Chemistry John Jeyes Award
2023 Canadian Society for Chemistry Tom Ziegler Award
2023 ACS Energy Letters Women at the Forefront of Energy
Selected publications
References
Year of birth missing (living people)
Living people
Iranian women chemists
21st-century chemists
21st-century women scientists
Iranian chemists
Computational chemists
Technical University of Denmark alumni
Stanford University people
Academic staff of the University of Calgary | Samira Siahrostami | [
"Chemistry"
] | 422 | [
"Computational chemistry",
"Theoretical chemists",
"Computational chemists"
] |
73,032,884 | https://en.wikipedia.org/wiki/Ganarake | Ganarake scalaris is an extinct species of lichen-like enigma, possibly within the division Mucoromycota first informally described as enigmatic cap-carbonate tubestones from basal Ediacaran sediments of the Southern Californian Noonday Formation. These tubestones were at first interpreted with a marine interpretation of the Noonday Formation as water escape structures, gas escape structures or as inverted stromatolites. However, associated paleosols and permineralized organic structures within the tubes with hyphae, spheroidal cells attached to the tubes and a remarkable organization of a thallus had remarkable similarities to habitats and microstructures of lichens. Ganarake has an isotopic composition and size comparable with a chlorophyte alga.
Etymology
Part of the genus name Gan is named in honour of paleontologist Tian Gan at the University of Maryland-College Park, who discovered similar Ediacaran fungi. The second half of the name arake is Greek for bowl. Scalaris refers to its ladder-like appearance as it branches in both Y and H-like forms.
Discovery
Even though the tubestones from the formation are now regarded as being of biological origin, they were originally interpreted as fluid escape structures or unique inverted stromatoliths. Historical evidence for a third option (lichenized fungi preserved in their growth positions) since the formation that G. scalaris was described from was compatible with the idea of lichens. Various microscopic observations confirmed fungal affinity with a stratified thallus of four layers. These layers are 1. Rectangular-cubic cells making up an upper cortex 2. A layer of spheroidal cells punctured and enveloped by slender hyphae 3. Medulla made out of the hyphae and 4. Lower cortex as thick as a few cells elaborated by intervals into multicellular rhizines extending down into the base of the sediment.
Description
Series of shallow and irregular cups are stacked up on each other and are in diameter. The cups branch off from a wide, possibly originally hollow, central hollow. The hollow is interpreted as originally being hollow because it is filled with sparry dolomite. These cup-shaped flanges consist of radially arranged, branching both pinnately and dichotomously from septate hyphae and expand until they define the cups foliose thalli, they are in turn overgrown by oxalate and carbonate crystals. In thin sections, they are reminiscent to thin ropes. When viewing the thalli in macerates they are flattened and foliose.
See also
List of Ediacaran genera
References
Ediacaran
Ediacaran life
Fossils of California
Fungus genera
Death Valley
Taxa described in 2022
Prehistoric fungi
Lichen genera
Prehistoric North America | Ganarake | [
"Biology"
] | 565 | [
"Fungi",
"Prehistoric fungi"
] |
73,033,921 | https://en.wikipedia.org/wiki/National%20Biotechnology%20Development%20Agency | National Biotechnology Development Agency (NABDA) is an agency established in 2001 under the Federal Ministry of Science and Technology, that implements policies, explores resources, conducts research, promotes, coordinates and develops biotechnology in Nigeria.
The NABDA also controls and supervises the introduction of genetically modified organisms into Nigeria.
Background and history
In July 2019, NABDA announced their invention of Anaerobic Digestion Technology digesters which can convert organic wastes to biogas.
In May 2020, NABDA worked with Nigeria Centre for Disease Control in the process of enabling local production of locally made testing kits for Coronavirus.
In March 2022, NABDA announced it was making research on reliable and affordable drugs for Lassa fever.
In December 2022, NABDA announced that they had locally produced a starter culture for the preparation of yoghurt with the two germs, Lactobacillus bulgaricus and Streptococcus thermophilus. In the same month, NABDA announced their livestock genetic experiments around artificial insemination for milk and meat improvement.
In January 2023, NABDA announced plans to release insect and drought-resistant maize to Nigerian farmers to improve food production. In the same month, they worked with National Committee on Naming, Registration and Release of Crop Varieties, Livestock Breed/Fisheries to release FARO68, a rice variety and 20 other crop varieties for farmers to boost food efficiency.
Leadership
Controversies
In June 2017, the Economic and Financial Crimes Commission (EFCC) arrested the then Director General of NABDA, Professor Lucy Jumeyi Ogbadu for alleged criminal conspiracy and diversion of N23 Million in public funds. This was part of a larger sum of N603 million naira. In an October 24, 2017 letter signed by the secretary of the EFCC, Ogbadu was absolved of any involvement in the alleged fraud. However, on January 9, 2018, it faulted the clearing and went on to file 49 charges against her. On August 30, 2021, a witness invited by the EFCC, Christopher Orji, the director of Bioresources Development Centre, Langtang, a sub agency under NABDA reportedly committed suicide.
In 2017, following the issuance of the permit for the commercialization of the genetically modified cotton, a group of 16 civil society organizations sued the National Biosafety Management Agency and National Biotechnology Development Agency. The court ruled in favour of the government agencies.
In November 2020, staff of NABDA protested citing unpaid promotion arrears, promotion examinations not being conducted, corruption and poor welfare as reasons.
In April 2022, Nnimmo Bassey decried NABDA's distribution of commercial quantities of Genetically Modified Cowpea to farmers without informing them on what the seeds were. Farmers went on to plant, harvest and sell the seeds without knowing they were GMCs. In September 2022, NABDA and other agencies insisted that such crops were safe for consumption and to tackle food crisis.
In November 2022, the Independent Corrupt Practices Commission arraigned Alex Akpa, a former acting director-general of NABDA, Famous Daunemigha, an ex-member of the Governing Board of NABDA and Wesley Ebi Siasia, an ex-director, finance and accounts of the agency, and others over alleged N400 million fraud. During the trial, they pleaded not guilty.
In November, 2024
Appointment Of Acting DG Of NABDA By Minister Creates Tension In Agency.
https://forefrontng.com/appointment-of-acting-dg-of-nabda-by-minister-creates-tension-in-agency/
References
Biotechnology by country
Government agencies of Nigeria | National Biotechnology Development Agency | [
"Biology"
] | 770 | [
"Biotechnology by country"
] |
73,034,100 | https://en.wikipedia.org/wiki/Stanhope%20Demonstrator | The Stanhope Demonstrator was the first machine to solve problems in logic. It was designed by Charles Stanhope, 3rd Earl Stanhope to demonstrate consequences in logic symbolically.
The first model was constructed in 1775. It consisted of two slides coloured red and gray mounted in a square brass frame. This could be used to demonstrate the solution to a syllogistic type of problem in which objects might have two different properties and the question was how many would have both properties. Scales marked zero to ten were used to set the numbers or proportions of objects with the two properties. This form of inference anticipated the numerically definite syllogism which Augustus De Morgan laid out in his book, Formal Logic, in 1847.
Construction
The device was a brass plate about four inches square which was mounted on a piece of mahogany which was three-quarters of an inch thick. There was an opening with a depression in the wood about one and a half inches square and half an inch deep. This opening was called the holon, meaning whole, and represented the full set of objects under consideration.
A slide of red translucent glass could be inserted from the right across the holon. A slide of gray wood could be slid under the red slide. When the device was used for the "Rule for the Logic of
Certainty", the gray slider was inserted from the left. When it was used for the "Rule for the Logic of Probability", the gray slider was inserted from above. The red and the gray sliders represented the two affirmative propositions which were being combined. Stanhope called these ho and los.
At least four of the devices with this square style were built. In 1879, Robert Harley wrote that he had one which he had been given by Stanhope's great-grandson, Arthur, who had kept one. The other two were owned by Henry Prevost Babbage – the son of Charles Babbage, who continued his work on the Analytical Engine. One of the devices was donated to the Science Museum, London by the last Earl in 1953. Other styles, such as circular models, were constructed, but these were less convenient.
See also
Logical piano
Venn diagram
References
Automated reasoning
Computer-related introductions in the 18th century
English inventions
History of logic
Mechanical calculators
Mechanical computers
One-of-a-kind computers | Stanhope Demonstrator | [
"Physics",
"Technology"
] | 474 | [
"Physical systems",
"Machines",
"Mechanical computers"
] |
73,034,584 | https://en.wikipedia.org/wiki/Scoop%20Package%20Manager | The Scoop Package Manager is a command-line installer for Microsoft Windows. Like other package managers, when commanded to install one program, it downloads and installs that program and also any dependencies of that program.
The system package manager Scoop is often used for installing web development tools and other software development tools.
Like other package managers,
Scoop makes it easy to discover out-of-date packages and update them.
Scoop installs apps in the current user's home directory, so it does not require admin permissions to install or update software. This allows Scoop to install software without UAC popups.
This is similar to a few other package managers that support installing apps in the current user's home directory (such as Listaller, AppImage, and ClickOnce). Most other package managers (such as Chocolatey) install applications in one central location, where they are usable by all the users on the system.
Some bloggers recommend to install both Chocolatey and Scoop.
Both have strong community support.
Scoop lets developers quickly set up a repeatable development environment.
References
See also
Windows Package Manager (winget)
Chocolatey
External links
Command-line software
Free package management systems
Software using the MIT license | Scoop Package Manager | [
"Technology"
] | 249 | [
"Command-line software",
"Computing commands"
] |
73,034,889 | https://en.wikipedia.org/wiki/HD%20182893 | HD 182893, also known as HR 7388 or rarely 60 G. Telescopii, is a solitary, yellowish-orange hued star located in the southern constellation Telescopium. It has an apparent magnitude of 6.13, making it barely visible to the naked eye even under ideal conditions. Based on Gaia DR3 parallax measurements, the object is estimated to be 328 light years away. However, it is approaching the Solar System with a heliocentric radial velocity of . At its current distance, HD 182893's brightness is diminished by 0.19 magnitudes due to interstellar dust. It has an absolute magnitude of +1.23.
HD 182893 has a stellar classification of K0/1 III, indicating that it is an evolved K-type star with the characteristics of a K0 and K1 giant star. It has 2.42 times the mass of the Sun but at the age of 761 million years, it has expanded to 8.08 times the radius of the Sun. It radiates 36.9 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of . HD 182893 is particularly metal enriched with an iron abundance 145% that of the Sun's ([Fe/H] = +0.16). Like most giant stars it spins slowly, having a projected rotational velocity of .
References
K-type giants
Telescopium
Telescopii, 60
CD-55 08180
182893
095866
7388 | HD 182893 | [
"Astronomy"
] | 325 | [
"Telescopium",
"Constellations"
] |
51,584,738 | https://en.wikipedia.org/wiki/Wirtgen%20Group | Wirtgen Group is an internationally operating German company in the construction industry. The company's core business is the development and production of machinery for road construction and maintenance.
Wirtgen Group employs around * people around the world and its annual turnover is around €3 billion. It also has local manufacturing plants in Brazil, China, and India, 55 distribution and service offices and over 150 authorized dealers around the globe.
History
In November 1961 Reinhard Wirtgen founded a small contracting business in Windhagen, Germany, starting with small haulage jobs and later specializing in road construction machinery with concrete breakers. Eventually Wirtgen expanded his fleet to 100 milling machines and 150 workers operating all over Germany. Reinhard Wirtgen progressed the product portfolio from hot milling to cold milling machines by the end of the 70s, which significantly increased the economic efficiency of the milling process. The international development of the company began when Reinhard Wirtgen set up the first subsidiaries outside Germany.
Reinhard Wirtgen systematically expanded his product portfolio at the production plant to four product divisions. In 1981, Wirtgen built the first surface miners for opencast mining and routing operations in hard rock. From 1987 onwards, Wirtgen introduced cold recycling as an economical method of road rehabilitation. Two years later, he incorporated the slipform paver division into his company to offer solutions for the construction of concrete roads and poured-in-place concrete profiles.
Jürgen and Stefan Wirtgen took over the management of the company in 1997. The expansion of the corporate group began with the integration of the road paver manufacturer Vögele. Hamm, a roller manufacturer, was integrated into Wirtgen Group in 1999. High investments in the three production plants resulted in the expansion of production capacities and efficiency, as well as a strong presence for the corporate group on a global scale.
In 2006 Wirtgen Group consolidated into two business lines: "Road Technologies" and "Mineral Technologies". The second line was established with the incorporation of Kleemann, a German manufacturer of mobile and stationary processing plants.
In 2014, the manufacturer of asphalt mixing plants Benninghoven was also integrated into the company.
In 2017, Wirtgen Group entered into a definitive agreement with John Deere to be purchased for $5.2 Billion.
Product brands
Wirtgen GmbH
Wirtgen GmbH is located in Windhagen in Rheinland-Pfalz, and it is the youngest and largest subcompany of the corporation. Wirtgen GmbH produces road milling machines and cold recyclers, as well as Surface miners for open cast mining operations.
Joseph Vögele AG
Joseph Vögele AG is based in Ludwigshafen am Rhein in Rheinland-Pfalz. The company is the world market leader for asphalt pavers and belongs to Wirtgen Group since 1996.
Hamm AG
HAMM AG, founded in Tirschenreuth in Bayern, is specialized in compaction technology. It is part of Wirtgen Group since 2000 and it manufactures road and soil compactors.
Kleemann GmbH
Located in Göppingen in Baden-Württemberg, KLEEMANN GmbH manufactures crushing and screening plants. It is part of Wirtgen Group since 2006.
Benninghoven GmbH & Co. KG
BENNINGHOVEN GmbH & Co. KG, located in Wittlich in Rheinland-Pfalz, is one of the largest recycling and asphalt mixing plant manufacturer in Germany. The company belongs to Wirtgen Group since 2014.
Local production sites
Ciber
Ciber Equipamentos Rodoviários is Wirtgen Group's local production facility for Latin America and completes the comprehensive product range with its own brand. The brand headquarter is located in the southern state of Rio Grande do Sul in Brazil, in the city of Porto Alegre. Ciber manufactures hot mix asphalt plants and pavers on five production lines. It also produces a model from the Wirtgen cold milling machine line and a Hamm roller, each of which are adapted to the requirements of the local market.
Wirtgen China
The local production facility for China is established in Langfang, near Beijing. The production range includes selected models of WIRTGEN cold milling machines, VÖGELE road pavers and HAMM rollers. Around 380 employees work in an area of 200.000 m2.
Wirtgen India
The new head office of Wirtgen India is located in the vicinity of Pune, an industrial center in the northwest of India. 672 employees work in the 129,100m² production area, production of Hamm of two models single-drum <model 311> and multi-drum <model HD99> compactors, Kleemanscreens and Vogele pavers
References
John Deere
Manufacturing companies established in 1961
German companies established in 1961
Construction equipment manufacturers of Germany
Companies based in Rhineland-Palatinate
Road construction
2017 mergers and acquisitions | Wirtgen Group | [
"Engineering"
] | 999 | [
"Construction",
"Road construction"
] |
51,584,759 | https://en.wikipedia.org/wiki/Throat%20clearing | Throat clearing is forcibly, sometimes mutedly, expelling air from one's lungs, sometimes to clear mucus, sometimes to attract attention to something. It is less vigorous than coughing.
Cause
Throat clearing may be articulated consciously or unconsciously, and may be a symptom of a number of laryngopharyngeal (upper respiratory tract) ailments. Occasionally the cause is a common cold or post-nasal drip. The nose dispatches mucus which is meant to assist clearing infections and allergens. Mucus which is thick is forced out with a throat clearing sound. Another cause is laryngopharyngeal reflux.
Mechanism
Throat clearing is a sound made at the back of the throat. The act of clearing the throat causes the folds in the throat to vibrate similar to a cough so it may be harmful if it is continuously practiced.
Onomatopoeia
When the pressure is restricted with a closed mouth, as is common in polite society, the sound is articulated as a single-syllable exclamation, written onomatopoeiacally as "hem"; or it may be articulated as a double-syllable sound, written as "ahem", which is expressed by inhaling slightly and then exhaling more forcibly. An alternate onomatopoeia written "hock" or "hawk" (as in "to hock a loogie") represents the impolite sound of loudly expelling a bolus of sputum with an open mouth.
Paralanguage
A deliberately executed throat clearing can be a nonverbal, paralingual form of metacommunication. A loud, exaggerated throat-clearing noise may sometimes be used to get attention; as in the case of a parent signaling to a child that they should behave.
References
Cough
Gestures | Throat clearing | [
"Biology"
] | 375 | [
"Behavior",
"Gestures",
"Human behavior"
] |
51,585,574 | https://en.wikipedia.org/wiki/System%20Security%20Services%20Daemon | The System Security Services Daemon (SSSD) is software originally developed for the Linux operating system (OS) that provides a set of daemons to manage access to remote directory services and authentication mechanisms. The beginnings of SSSD lie in the open-source software project FreeIPA (Identity, Policy and Audit). The purpose of SSSD is to simplify system administration of authenticated and authorised user access involving multiple distinct hosts. It is intended to provide single sign-on capabilities to networks based on Unix-like OSs that are similar in effect to the capabilities provided by Microsoft Active Directory Domain Services to Microsoft Windows networks.
References
External links
Unix network-related software
Linux software projects | System Security Services Daemon | [
"Technology"
] | 138 | [
"Computing stubs"
] |
51,585,932 | https://en.wikipedia.org/wiki/Hari%20Krishan%20Jain | Hari Krishan Jain (28 May 1930 - 8 April 2019) was an Indian cytogeneticist and plant breeder, known for his contributions to the field of genetic recombination and the control of interchromosome level. He is a former chancellor of the Central Agricultural University, Imphal, a former director of the Indian Agriculture Research Institute and a recipient of honours such as Rafi Ahmed Kidwai Award, Borlaug Award and Om Prakash Bhasin Award. The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded him the Shanti Swarup Bhatnagar Prize for Science and Technology, one of the highest Indian science awards, in 1966, for his contributions to biological sciences. He received the fourth highest Indian civilian honor, the Padma Shri, in 1981.
Biography
Hari Krishan Jain, born on 28 May 1930 in a Jain family in Gurgaon, in the Indian state of Haryana to Nemi Chand Jain and Chameli Devi, graduated in botany (BSc hons) from the University of Delhi in 1949 after which he secured an associate-ship from the Indian Agriculture Research Institute (IARI) in 1951. Subsequently, he pursued his doctoral studies at the Aberystwyth campus of the University College of Wales, on a Science Research Scholarship of the Royal Commission, London to secure his PhD and returned to India to start his career as a cytologist at IARI in 1956. He stayed at IARI until his superannuation from service as its Director in 1983 during which time he served as the Head of Genetics Division from 1966 to 1978. In 1984, he became associated with the International Service for National Agricultural Research of the Consultative Group for International Agricultural Research (CGIAR) where he served as the deputy director general. Later, he continued his academic life at the Rajasthan College of Agriculture of Maharana Pratap University of Agriculture and Technology, Udaipur until he was appointed as the chancellor of the Central Agricultural University, Imphal.
Jain is married to Kusum Lata and the couple has two children, Neera and Reena.
Legacy
Jain's early researches on Lilium, a genus of herbaceous plants, and its meiotic cell division revealed the correlation between the chromosome condensation and nucleolar synthesis. After joining IARI, he and his colleagues worked on the cytological mechanisms of genetic recombination, on Delphinium, a perennial flowering plant genus. His work contributed to the development of a protocol for controlling the interchromosome level, which was experimentally evidenced by subsequent researches by others. Later, he worked on tomato and Drosophila (popularly known as fruit flies) and his studies assisted in the discovery of chemical mutagen specificity. He headed the wheat development programs of IARI and initiated three such programs to develop high-yielding varieties of wheat. Ribosomal synthesis in plant cells was another area of his researches. He is credited with developing the concept of national multilineal complex of varieties and the proposal of the multiple and inter-cropping patterns, later popularized by the Indian Agricultural Research Institute. He authored five books which included Plant Breeding: Mendelian to Molecular Approaches Genetics: Principles, Concepts and Implications, and Green Revolution: History, Impact and Future and several articles which document the body of his work.
Jain has served as a member of the Scientific Advisory Committee (SAC-C) to the Government of India (1982–83) and the Uttar Pradesh State Planning Commission (1978–80). He chaired the Food and Agriculture Committee of the Bhabha Atomic Research Centre (1980–83) and the Indian chapter of the Man and the Biosphere Programme of the UNESCO (1978–83) and has been a member of the advisory committee on biotechnology of the Department of Science and Technology (1982–83). He chaired the consultative group on agriculture of the International Council for Science (ICSU) (1973) and is an Emeritus scientist of the Council for Scientific and Industrial Research, having been elected to the position in 1993. He also sat in the council of the Indian National Science Academy from 1979 to 1981 and served as the vice president of the National Academy of Agricultural Sciences from 2009 to 2011.
Books
Awards and honors
Jain received the Shanti Swarup Bhatnagar Prize for Science and Technology, the highest award of the Council of Scientific and Industrial Research in 1966 for his contributions to biological sciences. The Indian Council of Agricultural Research awarded him the Rafi Ahmed Kidwai Award the next year and he was elected for the Jawaharlal Nehru Fellowship in 1973 for his project, A Study of the Evolving Concepts of the Genetics and their Agricultural & Social Implications. The Government of India included him in the Republic Day honors list for the civilian award of the Padma Shri in 1981 and he received the Borlaug Award in 1982. The Om Prakash Bhasin Award reached him in 1986 and the National Academy of Agricultural Sciences honored him with Dr. B. P. Pal Award in 1999. He is also a recipient of the B. P. Pal Memorial Award of the Indian Science Congress Association which he received in 2004.
Jain was elected as a fellow of the Indian National Science Academy in 1974 and he became an elected fellow of the Indian Academy of Sciences in 1975. Two more Indian academies, the National Academy of Sciences, India and the National Academy of Agricultural Sciences elected him as their fellow in 1988 and 1991 respectively. The Indian Agricultural Research Institute honored him with the degree of Doctor of Science (honoris causa) in 2005 and the Central Agricultural University, where he served as the vice chancellor, instituted an annual award, the Dr. H. K. Jain CAU Award, in his honor in 2015, to recognize excellence in agricultural research.
See also
Indian Agricultural Research Institute
Central Agricultural University
Genetic recombination
Green Revolution
Green Revolution in India
Notes
References
External links
Recipients of the Shanti Swarup Bhatnagar Award in Biological Science
1930 births
Jawaharlal Nehru Fellows
People from Gurgaon district
Delhi University alumni
Indian agriculturalists
Alumni of the University of Wales
Indian geneticists
Plant breeding
Scientists from Haryana
Indian botanical writers
Council of Scientific and Industrial Research
Fellows of the Indian Academy of Sciences
Fellows of the Indian National Science Academy
Fellows of the National Academy of Sciences, India
Fellows of the National Academy of Agricultural Sciences
Recipients of the Padma Shri in science & engineering
Heads of universities and colleges in India
2019 deaths
Indian male writers
Writers from Haryana
20th-century Indian botanists | Hari Krishan Jain | [
"Chemistry"
] | 1,320 | [
"Plant breeding",
"Molecular biology"
] |
51,589,253 | https://en.wikipedia.org/wiki/Tic110%20family | The Chloroplast Envelope Anion Channel-forming Tic110 (Tic110) Family (TC#1.A.18) consists of proteins of the inner chloroplast envelope membrane. This family consists of the inner membrane protein import apparatus, and appears to be a protein import-related anion-selective channel. It has also been designated (1) IEP110, (2) IAP100 and (3) protein import-related anion channel (PIRAC).
Location
Most of the Tic110 protein is probably in the intermembrane space. Transport across the outer and inner membranes probably occurs by two independent processes.
Structure
Arabidopsis thaliana Tic 110 is 996 amino acyl residues long and exhibits 2 putative transmembrane segments (TMSs) near its N-terminus at positions 74-92 and 101-120. Biochemical analyses suggest that this protein is part of a 600 kDa complex. Tic110 has two proposed functions with naturally exclusive structures; a protein-conducting channel with 6 TMSs, and a scaffold with 2 N-terminal TMSs followed by a large soluble domain for binding transit peptides and other stromal translocon components. The C-terminal half of Tic110 possesses a rod-shaped helix-repeat structure that is too flattened and elongated to be a channel. The structure is most similar to the HEAT-repeat motif that functions as scaffolds for protein-protein interactions. The pore size was estimated to be about 6.5 Å.
Transport Reaction
The transport reactions across the chloroplast inner membrane catalyzed by Tic110 are:
(1) anions (out) ⇌ anions (in)
(2) proteins (out) → proteins (in)
References
Protein families
Membrane proteins
Transmembrane proteins
Transmembrane transporters
Transport proteins
Integral membrane proteins | Tic110 family | [
"Biology"
] | 403 | [
"Protein families",
"Protein classification",
"Membrane proteins"
] |
51,589,499 | https://en.wikipedia.org/wiki/Exchequer%20Standards | The Exchequer Standards may refer to the set of official English standards for weights and measures created by Queen Elizabeth I (English units), and in effect from 1588 to 1825, when the Imperial units system took effect, or to the whole range of English unit standards maintained by the Court of the Exchequer from the 1200s, or to the physical reference standards physically kept at the Exchequer and used as the legal reference until the such responsibility was transferred in the 1860s, after the Imperial system had been established.
The Exchequer standards made in the reign of Queen Elizabeth were not authorized by any statute. The standards were ordered by the royal authority, as appears from a roll of Michaelas terms in the 29th Elizabeth, preserved in the Queen's Remembrancer's Office, and containing the royal proclamation.
The Exchequer Standards were so called because their repository had always been the Court of the King's Exchequer.
Notably, Elizabeth I's redefinition of these standards instituted the English Doubling System, whereby each larger liquid measure equals exactly two of the next-smaller measure.
Historical development
1225–1265 The Great Charter (9 Hen. 3.)
The Great Charter of 1225 was the first legislative act in the English Statutes at Large, and is a repetition of Magna Carta by Henry III in 1300, although it is officially listed as act 9 Hen. 3.
With respect to Magna Carta requiring that there be one unified measure of volume, and another for length, thus unifying disparate measurement systems used to trade each different commodity, there is an argument made that this supposition is in error, and that it actually required these remain separately defined measures, but each be consistent across the kingdom:
The Rumford corn gallon of 1228, examined by the committee of the House of Commons in 1758, was found to be 266.25 cubic inches.
Corn
The quarter of London
Ale
The Ale gallon: of the same contents for liquid measure as the half peck was for dry
Wine
One measure of wine was a gallon, not of the same cubical contents as the half-peck and ale gallon, but which, when filled with wine, was of the same weight as the half-peck, or corn gallon, when filled with wheat.
Cloth
One breadth of cloth: two yards (ulna) within the lists
1266–1304 (51 Hen. 3.) Assize of bread and or ale
According to Secretary Adams,
Adams goes on to say (paraphrased and simplified):
The act noted that thirty-two kernels of average wheat from the middle of the ear were equal in weight to the silver penny sterling, new from the mint, round and without clipping—22.5 Troy grains.
It then defined that twenty such pence equal an ounce.
It then defined that twelve ounces equal one pound (sterling?), which Mr. Adams stated was 5,400 Troy grains.
It then defined that eight pounds (of fifteen ounces or 6,750 Troy grains; the commercial pound) equal a gallon of Gascoign wine, which was used to define the standard bushel. This wine was later called Claret or Bordeaux, and its specific gravity as compared with distilled water was 9,935 to 10,000, and weighed 250 troy grains per cubic inch. Mr. Adams continues his calculation to state that these eight pounds weighed 54,000 Troy grains, which divided by 250 gives a wine gallon of 216 cubic inches, which is very close to the Irish wine gallon (217.6 cubic inches) in effect in 1817. Yet when calculated based on the definition of the 63-gallon hogshead, Mr. Adams calculates the wine gallon to be 219.43 cubic inches.
It then defined that there are eight bushels in a quarter (by weight, not volume). So a bushel, filled with wheat, would exactly balance a keg containing eight gallons of wine, deducting the tare of both vessels.
Also, one eighth of this bushel, by volume, would be a vessel and called the ale gallon.
Thus, the key to the whole measurement system of 1266 was the weight of the silver penny sterling. This penny was of the Tower pound, which had been used at the London mint for centuries before the Norman conquest, and which continued as legal tender until 1527, when Henry VIII replaced it with the Troy pound. The Tower pound weighed Troy ounce less than the Troy pound ( of the Troy pound). Its penny, therefore weighed 22.5 Troy grains.
There was also another pound used c. 1266; the commercial pound, which equaled fifteen ounces was used to measure wine and most other items of commerce.
1304–1494 (31 Edw. 1.?)
At this point, there is not yet any mention of the avoirdupois or troy weights.
1494–1496 (10 Hen. 7.)
King Henry VII had 43 copies of the Exchequer standards made and distributed to the principal cities of the kingdom, but these were later found to be defective, and remade in 1496.
1496– (12 Hen. 7.)
The Weights and Measures Act 1496 (12 Hen. 7. c. 5) redefined the volumetric measures based on the Troy weights, officially discarding (though perhaps not on purpose) the Tower pound and the commercial pound for defining all measures:
Mr. Adams explains that this act of 1496 made several errors including inverting the order of the old statutes, assuming that the penny sterling, described in the acts of 1266 and 1304 was the penny weight troy (which it was not because the coinage had been adjusted since), and a belief that it was the measure, and not the weight, of eight gallons of wine, which constituted the bushel. It is here that the Guildhall gallon of 224 cubic inches is created. The same act creates the gallon of 231 cubic inches,
1428 2 Hen. 6. c. 2
King Henry VI decreed the following, which adjusted the sizes of casks
Competing systems
By 1862, there were multiple competing and confusing systems of measurement in the United Kingdom, and suggestions for simplification and possibly even switching to the French Metric system.
Systems of length
inch
foot
yard
mile (English: 1,760 yards; Scotch: 1,977 yards; Irish: 2,240 yards)
Nautical
fathoms (man-of-war: 6 feet; merchant vessel: 5.5 feet; fishing smack: 5 feet)
knots
leagues
geographical mile: 1 th mile
Surveyors' measures:
links
chains
rods
poles
perches
Systems of area
land
acre (several in England, including Falmouth: 4,840 square yards; Preston: 10,240; elsewhere 9,000)
rood (several in England)
Scotch acre
Irish acre
Cloth
yards
nails
ells (four different sorts)
Systems of weight
Grains, computed cdecimally, used for scientific purposes.
Troy weight, under 5 Geo. 4. c. 74, and 18 & 19 Vict. c. 72.
Troy ounce, with decimal multiples and divisions, called bullion weights, under 16 & 17 Vict. c. 29.
Banker's weights, to weigh 10, 20, 30, 50, 100, and 200 sovereigns.
Apothecaries weight.
Diamond weights and pearl weights, including carats.
Avoirdupois weight, under 5 Geo. 4. c. 74, and 18 & 19 Vict. c. 72.
Weights for hay and straw.
Wool weight, using as factors 2, 3, 7, 13, and their multiples.
Coal weights, decimal, under 1 & 2 Will. 4. c. 76, and 8 & 9 Vict. c. 101, Nos. 1, .5, .2, .1, .05, .025.
stone (about 10 different definitions)
hundredweight (100lbs, 112lbs, or 120lbs)
pound (Dutch, troy, or avoirdupois)
Systems of volume
Bushels (27 different ones, including 168 lbs., 73lbs., 80lbs., 60lbs., 70lbs., 63lbs, and so on)
Hoghead (ale: 54 gallons; wine: 63 gallons)
pipe of wine (port: 103 gallons; Teneriffe: 100 gallons; Madeira 92 gallons; Marsala 93 gallons)
cubic inches
Modifications
Addition of the Queen Anne Wine Gallon in 1707 (6 Ann. c. 27. s. 17.)
Definitions
23 Eliz. 1. c. 8 (1591)
35 Eliz. 1. c. 6 (1593)
35 Eliz. 1. c. 10. par. III (1593)
See also
English units
Winchester measure
Imperial units
References
External links
British Imperial System
CALICO TO WHISKEY: A CASE STUDY ON THE DEVELOPMENT OF THE DISTILLING INDUSTRY IN THE NAAS REVENUE COLLECTION DISTRICT, 1700-1921
Building With God
Medieval Economic Thought
Isn't a gallon, a gallon?
Imperial units
Standards organisations in the United Kingdom
Science in the Middle Ages
Obsolete units of measurement
Systems of units | Exchequer Standards | [
"Mathematics"
] | 1,866 | [
"Obsolete units of measurement",
"Quantity",
"Systems of units",
"Units of measurement"
] |
51,590,482 | https://en.wikipedia.org/wiki/Guerrilla%20crosswalk | A guerrilla crosswalk is a pedestrian crossing that has been modified or created without jurisdictional approval, and with the intent of improving pedestrian and other non-automobile safety. These interventions are a common strategy within tactical urbanism, a type of low-cost, often temporary change to the built environment intended to improve local livability. Guerilla crosswalks have been noted in news articles since at least 2009 and have become more well known as an urban strategy in recent years. The first known example of guerilla crosswalks can be found in Canada in 1987 when social activists John Valeriote and Erik Veldman created a crosswalk in Guelph, Ontario for students to safely cross a busy road in front of their school.
Background
Walkability and quality of life indicators are common topics in urban planners' and urban advocates' vocabulary in recent years. With the increasing body of research focused on measuring, and in some cases, marketing the walkability and quality of life in cities, citizens and decision-makers alike are focused on improving intersections, sidewalks, and streetscapes. Tactical urbanism is focused generally on small-scale, quick, and low-cost changes to a place. While some might consider it illegal, it is utilized by both activists and city planners alike when pilot programs and improvements are required immediately and when budget is a significant constraint.
Many guerrilla tactics react to the delays and inefficiencies in attempting to follow proper or legal channels. While guerilla crosswalks are usually quickly removed, the speed of the removal is often used to point out that cities do have the money to install and remove crosswalks.
This tactic is often a response to unsafe conditions at the interface of pedestrian and automobile circulation and is not without its opponents. One Public Works official commented in this way, "These changes to City streets are illegal, potentially unsafe and adding to the City's costs of maintenance and repair…. There is potential liability and risk management claims to both the City and the individuals involved." Crosswalks are a signal to drivers that pedestrians may be present. They are intended to group pedestrians for crossing at a safe time. The introduction of new crosswalks can be confusing to drivers and potentially give pedestrians a false sense of security.
Case studies and examples
Los Angeles
Crosswalk Collective LA, a group active throughout Los Angeles, has painted dozens of crosswalks since early 2022. In a statement to NPR, the group stated that "We […] have tried for years to request crosswalks and other safe streets infrastructure the official way. At every turn, we've been met with delays, excuses, and inaction from our city government, as well as active hostility to safe streets projects from sitting councilmembers."
The group does not publish a full list of painted crosswalks on its website to prevent them from being removed, and in effort to protect pedestrians. Out of those painted, some crosswalks have been removed, others have been upgraded into formal crosswalks by the City, and others remain in place.
The group's actions have been met with praise on social media by both local residents and those living elsewhere in the United States. The group has published a how-to guide and stencils on their website to facilitate similar efforts elsewhere in the country.
Seattle
Guerilla crosswalks appeared in Seattle in 2021 and 2022. The Seattle Department of Transportation responded by removing the crosswalks. City councilmember Andrew Lewis tweeted in response, "This is infuriating. We have the time and money, apparently, to expediently REMOVE a crosswalk, but it takes years to get around to actually painting one. No wonder neighbors took it upon themselves to act."
Baltimore
In the Baltimore neighborhood of Hampden, a 2011 repaving project endured longer than planned. After paving was complete, new crosswalks should have been painted, but the task was left undone with the contractor's justification that the cold weather prevented any street striping. This busy intersection was determined unsafe by many of the locals. Eventually one resident took it upon himself to paint the crosswalk lines late at the night. The man was thanked by the local city council.
References
Further reading
Pedestrian activism
Pedestrian crossings
Urban planning
Walking
DIY culture | Guerrilla crosswalk | [
"Engineering"
] | 874 | [
"Urban planning",
"Architecture"
] |
51,591,140 | https://en.wikipedia.org/wiki/Glossary%20of%20prestressed%20concrete%20terms | This page is a glossary of Prestressed concrete terms.
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
Y
See also
Cable-stayed bridge
Cantilever bridge
Concrete
Concrete beam
Concrete slab
Construction
Glossary of engineering
Glossary of civil engineering
Glossary of structural engineering
Incremental launch method
Precast concrete
Prestressed concrete
Prestressed structure
Reinforced concrete
Segmental bridge
Prestressing Wedges
References
Building engineering
Civil engineering
Prestressed concrete construction
Structural engineering
Prestressed Concrete
Concrete
Wikipedia glossaries using description lists | Glossary of prestressed concrete terms | [
"Technology",
"Engineering"
] | 119 | [
"Structural engineering",
"Building engineering",
"Structural system",
"Construction",
"Prestressed concrete construction",
"Civil engineering",
"Concrete",
"Architecture"
] |
51,591,592 | https://en.wikipedia.org/wiki/Estradiol%203-propionate | Estradiol 3-propionate, or 3-propanoylestradiol, also known as estra-1,3,5(10)-triene-3,17β-diol 3-propionate, is a semisynthetic, steroidal estrogen that was never marketed. It is an estrogen ester, specifically, a propionic acid ester of estradiol, and acts as a prodrug to it in vivo. The chemical structure of estradiol 3-propionate is contained within estradiol dipropionate, estrapronicate, and orestrate, all of which are also estradiol esters.
See also
List of estrogen esters § Estradiol esters
References
Abandoned drugs
Estradiol esters
Propionate esters
Synthetic estrogens | Estradiol 3-propionate | [
"Chemistry"
] | 179 | [
"Drug safety",
"Abandoned drugs"
] |
51,591,873 | https://en.wikipedia.org/wiki/Nitrogen%20dating | Nitrogen dating is a form of relative dating which relies on the reliable breakdown and release of amino acids from bone samples to estimate the age of the object. For human bones, the assumption of about 5% nitrogen in the bone, mostly in the form of collagen, allows fairly consistent dating techniques.
Compared to other dating techniques, Nitrogen dating can be unreliable because leaching from bone is dependent on temperature, soil pH, ground water, and the presence of microorganism that digest nitrogen rich elements, like collagen. Some studies compare nitrogen dating results with dating results from methods like fluorine absorption dating to create more accurate estimates. Though some situations, like thin porous bones might more rapidly change the dating created by multiple methods.
References
Lyndsie Krogh Sr. at Stanford University
Dating methodologies in archaeology
Nitrogen cycle
Nitrogen | Nitrogen dating | [
"Chemistry"
] | 172 | [
"Nitrogen cycle",
"Metabolism"
] |
51,592,571 | https://en.wikipedia.org/wiki/Mestilbol | Mestilbol (brand name Monomestro or Monomestrol), also known as diethylstilbestrol monomethyl ether, is a synthetic nonsteroidal estrogen of the stilbestrol group related to diethylstilbestrol. It was developed by Wallace & Tiernan Company, patented in 1940, and introduced for medical use in the 1940s, but is now no longer marketed. Mestilbol was available both as oral tablets and in oil for intramuscular injection. The drug is gradually demethylated in the body into diethylstilbestrol and hence is a prodrug of diethylstilbestrol. Mestilbol is a highly active estrogen, although somewhat less so than diethylstilbestrol, but is longer-lasting in comparison.
See also
List of estrogen esters § Ethers of nonsteroidal estrogens
References
Abandoned drugs
Estrogen ethers
4-Hydroxyphenyl compounds
Prodrugs
Synthetic estrogens
4-Methoxyphenyl compounds | Mestilbol | [
"Chemistry"
] | 222 | [
"Chemicals in medicine",
"Drug safety",
"Prodrugs",
"Abandoned drugs"
] |
51,592,861 | https://en.wikipedia.org/wiki/Creationism%20by%20country | This article presents an overview of creationism by country.
Africa
Kenya
In 2006 the Pentecostal church, led by Bishop Boniface Adoyo, launched a campaign to give less prominence to fossilised human bones displayed in the National Museum. These fossils, discovered by Richard Leakey in the Great Rift Valley region, are documented by science as remains of the earliest known human beings. Kenyan evangelical Christians have disputed the significance of those discoveries. Leakey and Bishop Adoyo were interviewed by Richard Dawkins for his The Genius of Charles Darwin series.
South Africa
A 2011 Ipsos survey found that 56% of responders in South Africa identified themselves as “creationists and believe that human beings were in fact created by a spiritual force such as the God they believe in and do not believe that the origin of man came from evolving from other species such as apes”.
Americas
Brazil
Brazil has had two creationist societies since the 1970s—the Brazilian Association for Creation Research and the Brazilian Creation Society. According to a 2004 survey, 41% of Brazil believe that "the first humans were created no more than 10,000 years ago."
A 2011 Ipsos survey found that 47% of responders in Brazil identified themselves as “creationists and believe that human beings were in fact created by a spiritual force such as the God they believe in and do not believe that the origin of man came from evolving from other species such as apes”.
United States
In the US some religious communities have refused to accept naturalistic explanations and tried to counter them. The term started to become associated with Christian fundamentalist opposition to human evolution and belief in a young Earth in 1929. Several US states passed laws against the teaching of evolution in public schools, as upheld in the Scopes Trial. Evolution was omitted entirely from school textbooks in most of the US until the 1960s. Since then, renewed efforts to introduce teaching creationism in American public schools in the form of Flood geology, creation science, and intelligent design have been consistently held to contravene the constitutional separation of church and state by a succession of legal judgments. The meaning of the term creationism was contested, but by the 1980s it had been co-opted by proponents of creation science and Flood geology.
Most of the anti-evolutionists of the 1920s believed in forms of old Earth creationism, which accepts geological findings and other methods of dating the Earth and believes that these findings do not contradict the Book of Genesis, but rejects evolution. At that time only a minority held to young Earth creationism, proponents of which believe that the Earth is thousands rather than billions of years old, and typically believe that the days in chapter one of the Book of Genesis are 24 hours in length. In the 1960s, this became the most prominent form of anti-evolution. From the 1860s forms of theistic evolution had developed; this term refers to beliefs in creation which are compatible with the scientific view of evolution and the age of the Earth, as held by mainstream Christian denominations. There are other religious people who support creationism, but in terms of allegorical interpretations of the Book of Genesis.
By the start of the 20th century, evolution was widely accepted and was beginning to be taught in American public schools. After World War I, popular belief that German aggression resulted from a Darwinian doctrine of "survival of the fittest" inspired William Jennings Bryan to campaign against the teaching of Darwinian ideas of human evolution. In the 1920s, the Fundamentalist–Modernist Controversy led to an upsurge of fundamentalist religious fervor in which schools were prevented from teaching evolution through state laws such as Tennessee’s 1925 Butler Act, and by getting evolution removed from biology textbooks nationwide. Creationism became associated in common usage with opposition to evolution.
In 1961 in the US, an attempt to repeal the Butler Act failed. The Genesis Flood by Henry M. Morris brought the Seventh-day Adventist biblically literal Flood geology of George McCready Price to a wider audience, popularizing the idea of young Earth creationism, and by 1965 the term "scientific creationism" had gained currency. The 1968 Epperson v. Arkansas judgment ruled that state laws prohibiting the teaching of evolution violate the Establishment Clause of the First Amendment to the United States Constitution which prohibits state aid to religion, and when in 1975 Daniel v. Waters ruled that a state law requiring biology textbooks discussing "origins or creation of man and his world" to give equal treatment to creation as per the Book of Genesis was unconstitutional, a new group identifying themselves as creationists promoted 'creation science' which omitted explicit biblical references.
In 1981, the state of Arkansas passed a law, Act 590, mandating that "creation science" be given equal time in public schools with evolution, and defining creation science as positing the "creation of the universe, energy, and life from nothing," as well as explaining the Earth's geology by "the occurrence of a worldwide flood." This was ruled unconstitutional at McLean v. Arkansas in January 1982 as the creationists' methods were not scientific but took the literal wording of the Book of Genesis and attempted to find scientific support for it. Louisiana introduced similar legislation that year. A series of judgments and appeals led to the 1987 Supreme Court ruling in Edwards v. Aguillard that it too violated the Establishment Clause of the First Amendment to the United States Constitution.
"Creation science" could no longer be taught in public schools, and in drafts of the creation science school textbook Of Pandas and People all references to creation or creationism were changed to refer to intelligent design. Proponents of the intelligent design movement organised widespread campaigning to considerable effect. They officially denied any links to creation or religion, and claimed that "creationism" only referred to young Earth creationism with Flood geology; but in Kitzmiller v. Dover the court found intelligent design to be religious, and unable to dissociate itself from its creationist roots, as part of the ruling that teaching intelligent design in public school science classes was unconstitutional.
The percentage of people in the US who accept the idea of human evolution declined from 45% in 1985 to 40% in 2005, while the percentage of people who reject evolution also declined from 48% to 39%. A Gallup poll reported that the percentage of people in the US who believe in a strict interpretation of creationism had fallen to 40% in 2010 after a high of 46% in 2006. However, the percentage rose back to 46% in 2012. The highest the percentage has risen between 1982 and 2010 was 47% in 1994 and 2000 according to the report. Gallup's survey indicated that belief in creationism has been relatively stable, although it has declined slightly in recent years. Its most recent poll found that 40% of Americans believe in creationism. The report found that Americans who are less educated are more likely to hold a creationist view while those with a college education are more likely to hold a view involving evolution. 47% of those with no more than a high school education believe in creationism while 22% of those with a post graduate education hold that view. The poll also found that church attendance dramatically increased adherence to a strict creationist view (22% for those who do not attend church, 60% for those who attend weekly). The higher percentage of Republicans who identified with a creationist view is described as evidence of the strong relationship between religion and politics as the U.S. Republicans also attend church weekly more than Democratic or independent voters. Non-Republican voters are twice as likely to hold a nontheistic view of evolution than Republican voters.
Among US states, acceptance of evolution has a strong negative correlation with religiosity and a strong positive relationship with science degrees awarded, bachelor's degree attainment, advanced degree attainment, average teacher salary, and GDP per capita. In other words, states in which more people say that religion is very important to their lives tend to show less acceptance of evolution. The better the education of individuals, their educational system, or the higher their income, the more they accept evolution, though the US as a country has a comparatively well educated population but lower acceptance of evolution than other countries.
Asia
South Korea
Since 1981, the Korea Association for Creation Research has grown to 16 branches, with 1000 members and 500 Ph.Ds. On August 22–24, 1991, recognizing the 10th anniversary of KACR, an International Symposium on Creation Science was held with 4,000 in attendance. In 1990, the book The Natural Sciences was written by Young-Gil Kim and 26 other fellow scientists in Korea with a creationist viewpoint. The textbook drew the interest of college communities, and today, many South Korean universities are using it.
Since 1991, creation science has become a regular university course at Myongji University, which has a centre for creation research. Since that time, other universities have begun to offer creation science courses. At Handong Global University, creationist Young-Gil Kim was inaugurated as president in March 1995. At Myongji University, creationist Woongsang Lee is a biology professor. The Korea Advanced Institute of Science and Technology is where the Research Association of Creation Science was founded and many graduate students are actively involved. In 2008, a survey found that 36% of South Koreans disagreed with the statement that "Human beings, as we know them today, developed from earlier species of animals." In May 2012, publishers of high school science textbooks decided to remove references to evolution following a petition by a creationist group. However, the ensuing controversy prompted the government to appoint a panel of scientists to look into the matter, and the government urged the publishers to keep the references to evolution following the recommendation of the panel.
Australia
In the late 1970s, Answers in Genesis, a creationist research organization, was founded in Australia. In 1994, Answers in Genesis expanded from Australia to the US. It subsequently expanded into the UK, Canada, South Africa and New Zealand. Creationists in Australia have been the leading influence on the development of creation science in the US for the last 20 years. Two of the three main international creation science organizations all have original roots within Australia – Answers in Genesis and Creation Ministries.
In 1980, the Queensland state government of Joh Bjelke-Petersen allowed the teaching of creationism as science to school children. On May 29, 2010, it was announced that creationism and intelligent design will be discussed in history classes as part of the new national curriculum. It will be placed in the subject of ancient history, under the topic of "controversies."
Ian Plimer, an anti-creationist geologist, reported being attacked by creationists. A few public lectures have been given in rented rooms at universities, by visiting American speakers, and speakers with doctorates purchased by mail from Florida sites. A court case claimed by Plimer to have been taken by him against prominent creationists found, according to him, "that the creationists had stolen the work of others for financial profit, that the creationists told lies under oath and that the creationists were engaged in fraud." The debate was featured on the science television program Quantum. In 1989, Plimer debated American creationist Duane Gish.
Europe
In recent years the teaching of creationism has become a subject of debate in a variety of countries including Germany, the UK, Italy, the Netherlands, Poland, and Serbia.
Creation "science" has been heavily promoted in immigrant communities in Western Europe, primarily by Turkish Islamic creationist Adnan Oktar. On October 4, 2007, the Parliamentary Assembly of the Council of Europe adopted The dangers of creationism in education, a resolution on the attempt by American-inspired creationists to promote creationism in European schools. It concludes "The war on the theory of evolution and on its proponents most often originates in forms of religious extremism closely linked to extreme right-wing political movements... some advocates of strict creationism are out to replace democracy by theocracy... If we are not careful, the values that are the very essence of the Council of Europe will be under direct threat from creationist fundamentalists."
France
A 2011 poll conducted by global research company Ipsos for Reuters found that 55% of French considered themselves as 'evolutionists' ("believe that human beings were in fact created over a long period of time of evolution growing into fully formed human beings they are today from lower species such as apes"), 36% don't know what to believe ("sometimes agree or disagree with theories and ideas put forward by both creationists and evolutionists"), and 9% considered themselves as 'creationists' ("believe that human beings were in fact created by a spiritual force such as the God they believe in and do not believe that the origin of man came from evolving from other species such as apes").
Germany
The board of the federation of Protestant Churches in Germany, the Rat der EKD clearly rejects both creationism and intelligent design from a theological standpoint. It refers to both Calvin and Luther as proponents of a creatio continua, an ongoing creation. EKD stands as well for an intense and fruitful exchange between churches, science and theology in the general public and on university level. Germany has a longstanding tradition of religious education in public (state funded) schools, starting with the Prussian education system in the 18th century.
In 1978, British chemist A. E. Wilder-Smith, who came to Germany after World War II and lectured at Marburg and other cities, published a book arguing against evolution, The Natural Sciences Know Nothing of Evolution (1978). At the end of the year Horst W. Beck became a creationist. Both an engineer and theologian, he was a leading figure in the Karl-Heim-Gesellschaft (Karl Heim Society) and had previously published articles and books defending theistic evolution. Together with other members of the society, which they soon left, he followed the arguments of Willem Ouweneel, a Dutch biologist lecturing in Germany. Beck soon found other scientists who had changed their view or were "hidden" creationists. Under his leadership, the first creationist society was founded, Wort und Wissen—lit. "Word and Knowledge". Three book series were soon published, an independent creationist monthly journal started (Factum), and the first German article in the Creation Research Society Quarterly was published.
In 2006, a documentary on Arte television network, Von Göttern und Designern ("Genesis vs. Darwin") by filmmaker Frank Papenbroock, demonstrated that creationism had already been taught in biology classes in at least two schools in Giessen, Hesse, without this being noticed. During this, the Education Minister of Hessen, Karin Wolff, said she believed creationism should be taught in biology class as a theory, like the theory of evolution: "I think it makes sense to bring up multidisciplinary and interdisciplinary problems for discussion." In 2009, an article on the German news site Spiegel Online stated approximately 20% of people disbelieve evolutionary theory in Germany. More recently, a 2011 Ipsos poll commissioned by Reuters found 12% of Germans identify as creationists.
Romania
In Romania, in 2002, the Ministry of Education approved the use of a biology book endorsing creationism, titled Biologie clasa a IX-a – Măiestrie şi strălucire divină în biosferă ("Biology Class IX – Divine Mastery and Brilliance in the Biosphere"), in public high schools. Following a protest of the Romanian Humanist Association the Romanian Ministry of Education replied that the book is not a "textbook" but merely an "accessory." The president of the Association labelled the reply as "disappointing" since, whether a textbook or an accessory, the book remains available for usage in schools. Reports indicate that at least one teacher in Oradea did use the book.
Serbia
On September 7, 2004, the Serbian Minister for Education and Sport, Ljiljana Čolić, temporarily banned evolution from being taught in the country. After statewide outcry she resigned on September 16, 2004, from her post.
Switzerland
A 2006 international survey found that 30% of the Swiss reject evolution, one of the highest national percentages in Europe. Another survey in 2007, commissioned by the Christian organization Pro Genesis, controversially claims 80% of Swiss want creationism taught alongside evolution in biology class. This resulted in schools in the Canton of Bern printing science textbooks that presented creationism as a valid alternative theory to evolution. Scientists and education experts harshly criticized the move, which quickly prompted school authorities to revise the books.
United Kingdom
Since the development of evolutionary theory by Charles Darwin in England, where his portrait appears on the back of the revised Series E £10 note issued in 2000, significant shifts in British public opinion have occurred. A 2006 survey for the BBC showed that "more than a fifth of those polled were convinced by the creationist argument," a massive decrease from the almost total acceptance of creationism before Darwin published his theory. A 2010 Angus Reid poll found that "In Britain, two-thirds of respondents (68%) side with evolution while less than one-in-five (16%) choose creationism. At least seven-in-ten respondents in the South of England (70%) and Scotland (75%) believe human beings evolved from less advanced life forms over millions of years." A subsequent 2010 YouGov poll on the origin of humans found that 9% opted for creationism, 12% intelligent design, 65% evolutionary theory and 13% did not know.
Speaking at the British Science Association's British Science Festival at the University of Liverpool in 2008, Michael Reiss estimated that about only 10% of children were from a family that supported a creationist rather than evolutionary viewpoint. Richard Dawkins has been quoted saying "I have spoken to a lot of science teachers in schools here in Britain who are finding an increasing number of students coming to them and saying they are Young Earth creationists."
The director of education at the Royal Society has said that creationism should be discussed in school science lessons, rather than be excluded, to explain why creationism had no scientific basis. Wales has the largest proportion of theistic evolutionists—the belief that evolution is part of God's plan (38%). Northern Ireland has the highest proportion of people who believe in 'intelligent design' (16%), which holds that "certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection." Some private religious schools in the UK teach creationism rather than evolution. The British Humanist Association and leading scientists campaigned to make creationism illegal in state funded schools from 2011 onwards. In 2014 they achieved their goal when the Department for Education updated the funding contracts of Academies and Free Schools to this effect, and at the same time, clarified that creationism being taught as science contravened existing 'British values' requirements.
Muslim world
A 2007 study of religious patterns found that only 8% of Egyptians, 11% of Malaysians, 14% of Pakistanis and 16% of Indonesians agree that Darwin's theory is probably or most certainly true, and a 2006 survey reported that about a quarter of Turkish adults agreed that human beings evolved from earlier animal species. Surveys carried out by researchers affiliated with McGill University's Evolution Education Research Centre found that in Egypt and Pakistan, while the official high school curriculum does include evolution, many of the teachers there do not believe in it themselves, and will often tell their students so.
Currently in Egypt, evolution is taught in schools but Saudi Arabia and Sudan have both banned the teaching of evolution in schools. In recent times, creationism has become more widespread in other Islamic countries.
The results of a survey of the adherence to creation science of 5,700 teachers from 14 countries was presented during the 2008 XIII IOSTE Symposium in Izmir, Turkey. Lebanon, Jordan, Tunisia, Morocco and Algeria had 62% to 81% of creationist teachers (with no difference between biologists and others). Romania and Burkina Faso had 45% to 48% of creationist teachers, with no difference between biologists and other in Romania, but a clear difference (p<0.001) in Burkina Faso (with 61% of creationists for the not biology teachers). Portugal and Cyprus had 15% to 30% of creationist teachers, with no significant difference between biologists, but a significant difference in Portugal (p=0.004, 17% and 26%).
Iran
Iranian scientific development, especially the health-related aspects of biology, has been a goal of the Islamic government since the revolution of 1979. Since Iranian traditional practice of Shi'a religion is not preoccupied with Qur'anic literalism as in case of Saudi Wahhabism but ijtihad, many influential Iranian Shi'ite scholars, including several who were closely involved in Iranian Revolution, are not opposed to evolutionary ideas in general, disagreeing that evolution necessarily conflicts with the Muslim mainstream. Iranian pupils, since 5th grade of elementary school, learn only about evolution, thus portraying geologists and scientists in general as authoritative voices of scientific knowledge.
Turkey
Following the 1980 Turkish coup d'état, the military leadership and subsequent governments promoted Islamism to promote national unity, which eventually included translation and distribution of materials from the US Institute for Creation Research and creationist high-school textbooks. A survey published in 2008 found that about 25% of people in Turkey accepted evolution as an explanation for how life came to exist. In 2008, Richard Dawkins' website was banned in Turkey; the ban was lifted in July 2011. As of 2009, creationism had become the government's official position on origins. In 2009, the Turkish government agency Scientific and Technological Research Council of Turkey (TÜBİTAK), publisher of the popular Turkish science magazine Bilim ve Teknik (Science and Technology), was accused of stripping a cover story about the life and work of Charles Darwin from the March 2009 issue of the Council's publication just before it went to press. The planned portrait of Darwin for the magazine's cover was replaced and the editor of the magazine, Çiğdem Atakuman, claims that she was removed from her post. Most of the Turkish population expressed support for the censorship. In 2012, it was found that the government's internet content filter, designed to prevent the public having access to pornographic websites, also blocked the words 'evolution' and 'Darwin' on one mode of the filter.
In 2017, Turkey announced plans to end the teaching of evolution in Turkish schools, with chairman of the Board of Education, Alpaslan Durmuş, claiming it was too complicated and "controversial" a topic for students.
References
Creationism | Creationism by country | [
"Biology"
] | 4,626 | [
"Creationism",
"Biology theories",
"Obsolete biology theories"
] |
51,593,278 | https://en.wikipedia.org/wiki/N%2CN-Dimethylphenethylamine | N,N-Dimethylphenethylamine (N,N-DMPEA) is a substituted phenethylamine that is used as a flavoring agent. It is an alkaloid that was first isolated from the orchid Pinalia jarensis. Its aroma is described as "sweet, fishy". It is mainly used in cereal, cheese, dairy products, fish, fruit and meat. It is also being used in pre-workout and bodybuilding supplements with claims of a stimulant effect.
There is also evidence suggesting that N,N-DMPEA acts as a TAAR1 agonist in humans, and as a 5-HT1A ligand in rats. Some less conclusive research also indicated that it had interaction with MAO-B, most likely as an enzyme substrate and not an inhibitor.
N,N-DMPEA is a positional isomer of methamphetamine. Instead of the methyl group attached to the alpha position of phenylethylamine, it is attached to the nitrogen group. Both substances have the chemical formula C10H15N.
Safety
N,N-DMPEA has been found to be safe for use as a flavoring agent by the Flavor and Extract Manufacturers Association (FEMA) Expert Panel and also by the Joint Expert Committee on Food Additives (JECFA)—a collaboration between the Food and Agricultural Organization of the United Nations (FAO) and the World Health Organization.
Legality
In the United States, N,N-DMPEA may be considered a Schedule II substance as a positional isomer of methamphetamine (C10H15N), due to the Schedule II definition of methamphetamine defined as "any quantity of methamphetamine, including its salts, isomers, and salts of isomers".
Notes
References
Phenethylamine alkaloids
Food additives | N,N-Dimethylphenethylamine | [
"Chemistry"
] | 397 | [
"Alkaloids by chemical classification",
"Phenethylamine alkaloids"
] |
51,594,670 | https://en.wikipedia.org/wiki/Rhopalosiphum%20padi%20virus | Rhopalosiphum padi virus (RhPV) is a member of Dicistroviridae family, which includes cricket paralysis virus (CrPV), Plautia stali intestine virus and Drosophila C virus. Its 5'UTR region contains an internal ribosome entry site (IRES) element with a cross-kingdom activity. It can function efficiently in mammalian, plant and insect translation systems.
Testing of R. padi aphids collected from different sites in Sweden revealed the presence of RhPV in wild aphid populations for the first time in Europe. Virus could be detected in several life stages of R. padi, including sexual individuals and eggs, establishing an over-wintering route for the virus.
References
Cis-regulatory RNA elements
Dicistroviridae | Rhopalosiphum padi virus | [
"Biology"
] | 169 | [
"Virus stubs",
"Viruses"
] |
51,595,918 | https://en.wikipedia.org/wiki/NGC%20208 | NGC 208 is a spiral galaxy located approximately 229 million light-years from the Solar System in the constellation Pisces. It was discovered on October 5, 1863, by Albert Marth.
Supernova
One supernova has been observed in NGC 208: SN 2024luo (type Ia, mag. 17.2).
See also
Spiral galaxy
List of NGC objects (1–1000)
Pisces (constellation)
References
External links
SEDS
0208
Spiral galaxies
2420
Pisces (constellation)
Astronomical objects discovered in 1863 | NGC 208 | [
"Astronomy"
] | 111 | [
"Pisces (constellation)",
"Constellations"
] |
51,595,948 | https://en.wikipedia.org/wiki/NGC%20209 | NGC 209 is a lenticular galaxy located approximately 175 million light-years from the Solar System in the constellation Cetus. It was discovered on October 9, 1885, by Francis Leavenworth.
See also
List of NGC objects (1–1000)
References
External links
SEDS
0209
2338
Astronomical objects discovered in 1885
Galaxies discovered in 1885
Cetus
Unbarred lenticular galaxies | NGC 209 | [
"Astronomy"
] | 79 | [
"Cetus",
"Constellations"
] |
51,596,362 | https://en.wikipedia.org/wiki/Defence%20in%20depth%20%28non-military%29 | A defence in depth uses multi-layered protections, similar to redundant protections, to create a reliable system despite any one layer's unreliability.
Examples
The term defence in depth is now used in many non-military contexts.
Fire prevention
A defence in depth strategy to fire prevention does not focus all the resources only on the prevention of a fire; instead, it also requires the deployment of fire alarms, extinguishers, evacuation plans, mobile rescue and fire-fighting equipment and even nationwide plans for deploying massive resources to a major blaze.
Defense-in-depth is incorporated into fire protection regulations for nuclear power plants. It requires preventing fires, detecting and extinguishing fires that do occur, and ensuring the capability to safely shutdown.
Engineering
Defence in depth may mean engineering which emphasizes redundancy – a system that keeps working when a component fails – over attempts to design components that will not fail in the first place. For example, an aircraft with four engines will be less likely to suffer total engine failure than a single-engined aircraft no matter how much effort goes into making the single engine reliable. Charles Perrow, author of Normal accidents, wrote that sometimes redundancies backfire and produce less, not more reliability. This may happen in three ways: First, redundant safety devices result in a more complex system, more prone to errors and accidents. Second, redundancy may lead to shirking of responsibility among workers. Third, redundancy may lead to increased production pressures, resulting in a system that operates at higher speeds, but less safely.
Nuclear
In nuclear engineering and nuclear safety, all safety activities, whether organizational, behavioural or equipment related, are subject to layers of overlapping provisions, so that if
a failure should occur it would be compensated for or corrected without causing harm to individuals or the public at large. Defence in depth consists in a hierarchical deployment of different levels of equipment and procedures in order to maintain the effectiveness of physical barriers placed between radioactive materials and workers, the public or the environment, in normal operation, anticipated operational occurrences and, for some barriers, in accidents at the plant. Defence in depth is implemented through design and operation to provide a graded protection against a wide variety of transients, incidents and accidents, including equipment failures and human errors within the plant and events initiated outside the plan.
Existential risk mitigation
Defense in depth is a useful framework for categorizing existential risk mitigation measures into three layers of defense:
Prevention: Reducing the probability of a catastrophe occurring in the first place. Example: Measures to prevent outbreaks of new highly-infectious diseases.
Response: Preventing the scaling of a catastrophe to the global level. Example: Measures to prevent escalation of a small-scale nuclear exchange into an all-out nuclear war.
Resilience: Increasing humanity's resilience (against extinction) when faced with global catastrophes. Example: Measures to increase food security during a nuclear winter.
Human extinction is most likely when all three defenses are weak, that is, "by risks we are unlikely to prevent, unlikely to successfully respond to, and unlikely to be resilient against".
Information security
Likewise, in information security / Information Assurance defence in depth represents the use of multiple computer security techniques to help mitigate the risk of one component of the defence being compromised or circumvented. An example could be anti-virus software installed on individual workstations when there is already virus protection on the firewalls and servers within the same environment. Different security products from multiple vendors may be deployed to defend different potential vectors within the network, helping prevent a shortfall in any one defence leading to a wider failure; also known as a "layered approach".
See also
Defense in depth (military strategy)
Defence-in-depth (Roman military)
References
Safety engineering | Defence in depth (non-military) | [
"Engineering"
] | 778 | [
"Safety engineering",
"Systems engineering"
] |
51,596,724 | https://en.wikipedia.org/wiki/Anatomical%20variation | An anatomical variation, anatomical variant, or anatomical variability is a presentation of body structure with morphological features different from those that are typically described in the majority of individuals. Anatomical variations are categorized into three types including morphometric (size or shape), consistency (present or absent), and spatial (proximal/distal or right/left).
Variations are seen as normal in the sense that they are found consistently among different individuals, are mostly without symptoms, and are termed anatomical variations rather than abnormalities.
Anatomical variations are mainly caused by genetics and may vary considerably between different populations. The rate of variation considerably differs between single organs, particularly in muscles. Knowledge of anatomical variations is important in order to distinguish them from pathological conditions.
A very early paper published in 1898, presented anatomic variations to have a wide range and significance, and before the use of X-ray technology, anatomic variations were mostly only found on cadaver studies. The use of imaging techniques have defined many such variations.
Some variations are found in different species such as polydactyly, having more than the usual number of digits.
Variants of structures
Muscles
Kopsch gave a detailed listing of muscle variations. These included the absence of muscles; muscles that were doubled; muscles that were divided into two or more parts; an increase or decrease in the origin or insertion of the muscle; and the joining to adjacent organs.
The palmaris longus muscle in the forearm is sometimes absent, as is the plantaris muscle in the leg.
The sternalis muscle is a variant that lies in front of the pectoralis major and may show up on a mammogram.
Bones
Usually there are five lumbar vertebrae but sometimes there are six, and sometimes there are four.
Joints
A discoid meniscus is a rare thickened lateral meniscus in the knee joint that can sometimes be swollen and painful.
Organs
The lungs are subject to anatomical variations.
Clinical significance
Accessory small bones called ossicles may be mistaken for avulsion fractures.
See also
Supernumerary body part
Visible difference
References
External links
Atlas of human anatomical variations
Anatomy | Anatomical variation | [
"Biology"
] | 429 | [
"Anatomy"
] |
51,596,854 | https://en.wikipedia.org/wiki/LiSiCA | LiSiCA (Ligand Similarity using Clique Algorithm) is a ligand-based virtual screening software that searches for 2D and 3D similarities between a reference compound and a database of target compounds which should be represented in a Mol2 format. The similarities are expressed using the Tanimoto coefficients and the target compounds are ranked accordingly. LiSiCA is also available as LiSiCA PyMOL plugin both on Linux and Windows operating systems.
Description
As an input LiSiCA requires at least one reference compound and database of target compounds. For 3D screening this database has to be a pregenerated database of conformations of target and for 2D screening a topology, that is, a list of atoms and bonds, for each target compound. On each step the algorithm compares reference compound to one of the compounds from target compounds based on their 2D or 3D representation. Both compounds(molecules) are converted to molecular graphs. In 2D and 3D screening the molecular graph vertices represent atoms. In 2D screening edges of molecular graph represent covalent bonds while in 3D screening edges are drawn between every pair of vertices and have no chemical meaning. A product graph generated from molecular graphs is then searched using fast maximum clique algorithm to find the largest substructure common to both compounds. The similarity between compounds is calculated using Tanimoto coefficients and target compounds are ranked according to their Tanimoto coefficients.
Feature overview
LiSiCA can search 2D and 3D similarities between a reference compound and a database of target compounds. It takes as an input at least one reference compound and a database of target compounds. By default it returns only the compound most similar to the reference compound out of all compounds in database of target compounds.
Other optional parameters LiSiCA uses are:
Number of CPU threads to useDefault value: the default is to try to detect the number of CPUs and use all of them or, failing that, use 1
Product graph dimensionPossible input: 2, 3Default value: 2
Maximum allowed atom spatial distance difference for the 3D product graph measured in angstromsDefault value: 1.0
Maximum allowed shortest path difference for the 2D product graph measured in the number of covalent bonds between atomsDefault value: 1
Consider hydrogensDefault value: False
Number of highest ranked molecules to write to outputDefault value: 0
Maximum allowed number of highest scoring conformations to be outputtedDefault value: 1
In addition LiSiCA PyMOL plugin also offers to load saved results.
History
LiSiCA Software (March 2015)
LiSiCA PyMOL plugin (March 2016)
Interesting fact
The Slovene word lisica means 'fox', which is why the logo of LiSiCA software is a fox holding two molecules.
References
External links
LiSiCA software
LiSiCA plugin
Molecular modelling
Chemistry software | LiSiCA | [
"Chemistry"
] | 573 | [
"Molecular physics",
"Chemistry software",
"Theoretical chemistry",
"Molecular modelling",
"nan"
] |
51,598,644 | https://en.wikipedia.org/wiki/Royal%20Rainmaking%20Project | The Thailand Royal Rainmaking Project (, ) was initiated in November 1955 by King Bhumibol Adulyadej. Thai farmers repeatedly suffered the effects of drought. The king resolved to do something about it and proposed a solution to the dearth of rain: artificial rainmaking, or cloud seeding. The program is run by the Department of Royal Rainmaking and Agricultural Aviation. There is no impact evaluation or effectiveness reported.
History
The king discovered that many areas faced the problem of drought. Over 82% of Thai agricultural land relied on rainfall. Thai farmers were not able to grow crops for lack of water. Although scientific evidence seems to suggest that cloud seeding does not ameliorate droughts, the Royal Rainmaking Project debuted on 20 July 1969 at the king's behest, when the first rainmaking attempt was made at Khao Yai National Park. Dry ice flakes were scattered over clouds. Reportedly, some rainfall resulted. In 1971, the government established the Artificial Rainmaking Research and Development Project within the Thai Ministry of Agriculture and Cooperatives.
Recognition
The king received recognition for the Royal Rainmaking Project from the EUREKA organization in 2001 for an invention that is beneficial to the world. In 2009, Jordan received permission from Thailand to use the technique.
Department of Royal Rainmaking and Agricultural Aviation
The Department of Royal Rainmaking and Agricultural Aviation (DRRAA) was established on 15 September 1992, reporting to the Office of the Permanent Secretary for the Ministry of Agriculture and Cooperatives. The budget of the Department of Royal Rainmaking and Agricultural Aviation in FY2019 was 2,224 million baht.
DRRAA in 2019 has flown about 6,000 rain seeding flights, up from its yearly average of 5,000 sorties. DRRAA employs 71 pilots who fly 39 cloud seeding aircraft from Royal Rain Operations Centres in Chiang Mai, Nakhon Sawan, Khon Kaen, Rayong, and Surat Thani. The department plans to open new centres in Buriram and Phitsanulok and to hire an additional 44 pilots.
In February 2018, with Bangkok suffering under a haze of ultra-fine dust, the government turned to the DRRAA to seed clouds to create artificial rain over the city. The Pollution Control Department issued warnings that particulate levels had soared to 94 micrograms per cubic metre of air in some areas, far above the safety limit of 50 mcg. The prime minister assured Thais that, "...[rainmaking] should bring some relief at least in the short term,..." Fumes from vehicles, construction sites, and factories in adjacent provinces contribute to the smog that contains dust known as particulate matter PM2.5. "The department will continue to check the weather every day and will make rain as soon as possible", said the prime minister.
Technique
Agitation: Seeding hygroscopic chemicals stimulates a mass of air to rise higher to create humidity. This helps nature to form rain clouds, and it increases the potential amount of rainfall.
Fattening: Fattening of the rain clouds is done by scattering exothermic-hygroscopic chemicals to make droplets of water condense.
Attacking: Flying a plane through the heavy clouds accelerates the process of raindrop formation.
See also
Chaipattana Foundation
Crown Property Bureau
Royal Project Foundation
Sufficiency Economy
Silver iodide
Weather modification
References
External links
Department of Royal Rainmaking and Agricultural Aviation
Weather modification
Water in Thailand
Royal Initiative Projects
1955 establishments in Thailand | Royal Rainmaking Project | [
"Engineering"
] | 721 | [
"Planetary engineering",
"Weather modification"
] |
49,286,876 | https://en.wikipedia.org/wiki/Xue%20Qikun | Xue Qikun (; born December 1963) is a Chinese physicist. He is a professor of Tsinghua University, Beijing. He has done much work in condensed matter physics, especially on superconductors and topological insulators. In 2013, Xue was the first to achieve the quantum anomalous Hall effect (QAHE), an unusual orderly motion of electrons in a conductor, in his laboratory at Tsinghua University. Xue is a member of the Chinese Academy of Sciences, vice president for research of Tsinghua University, and director of State Key Lab of Quantum Physics. In 2016, he was one of the first recipients of the new Chinese Future Science Prize for experimental discovery of high-temperature superconductivity at material interfaces and the QAHE. This award has been described as "China's Nobel Prize".
Career
Xue earned his PhD from the Institute of Physics, Chinese Academy of Sciences in 1994. From 1994 to 2000, he worked as a research associate at Institute for Materials Research, Tohoku University, Japan, and as a visiting assistant professor at the Physics Department of North Carolina State University, US. He became a professor at the Institute of Physics, Chinese Academy of Sciences, in 1999, and since 2005 has worked as a professor in the Physics Department of Tsinghua University. He is a partner investigator in Australia's ARC Centre of Excellence in Future Low-Energy Electronics Technologies. In 2020, he became the president of Southern University of Science and Technology (SUSTech).
Research and achievements
Xue pioneered high quality thin films of topological insulators and, in 2013, first achieved the quantum anomalous Hall effect (QAHE), at Tsinghua University. Nobel Laureate Chen-Ning Yang called this discovery "worthy of a Nobel Prize".
Xue's current research aims at preparation of low-dimensional structures exhibiting pronounced quantum phenomena, and understanding of growth dynamics and quantum mechanical effects on solid surfaces and in thin films, including:
atomic-scale probing of surface electronic and magnetic properties by scanning tunneling microscopy and spectroscopy
molecular beam epitaxial growth of novel quantum materials including low-dimensional and interface-related superconductivity and topological insulators
quantum size effects in various low-dimensional structures
study of electronic band structures of thin films using angle resolved photoemission spectroscopy (ARPES) and molecular beam epitaxy.
exploration of novel quantum phenomena in materials with transport measurements
development of new measurement techniques with high spatial and energy resolutions
Honors
2004, State Natural Science Second Class Award
2005, member of the Chinese Academy of Sciences
2010, TWAS Prize in Physics
2011, State Natural Science Second Class Award
2011, Outstanding Scientific Research Team Award
2014, Outstanding Scientist Award
2016, Future Science Prize in physical science
2020, Fritz London Memorial Prize for low-temperature physics
2024, Oliver E. Buckley Prize
Selected papers
Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
Superconductivity in One-Atomic-Layer Metal Films Grown on Si(111)
Superconductivity Modulated by Quantum Size Effects
References
1963 births
Living people
Educators from Shandong
Members of the Chinese Academy of Sciences
Quantum physicists
People from Linyi
Physicists from Shandong
Shandong University alumni
Academic staff of Tsinghua University
TWAS laureates
Fellows of the American Physical Society
Highest Science and Technology Award winners | Xue Qikun | [
"Physics"
] | 687 | [
"Quantum physicists",
"Quantum mechanics"
] |
49,287,387 | https://en.wikipedia.org/wiki/NGC%20986 | NGC 986 is a barred spiral galaxy in the southern constellation of Fornax, located about 76 million light-years away. It was discovered on August 5, 1826, by the Scottish astronomer James Dunlop, who described it as a "faint nebula, of an irregular round figure". The galaxy has an angular size of with a visual magnitude of 10.9. It belongs to the Fornax Cluster of galaxies. This galaxy has a nearby companion, NGC 986A, at an angular separation of , corresponding to a projected separation of . The two appear unconnected.
The morphological class of NGC 986 is (R′1)SB(rs)b, indicating this is a barred spiral (SB) with an outer pseudo-ring (R′1), an incomplete inner ring (rs), and moderately wound spiral arms (b). The galactic plane is inclined at an angle of 37° to the line of sight from the Earth. The resulting ellipsoidal profile has its major axis aligned along a position angle of 127°.
The nucleus of NGC 986 is undergoing intense star formation and there is an H II region at the core. The large central bar extends and is rich in dense gas. The galaxy contains two large, extended and slightly warped arms that begin at each end of the central bar, forming an S-shape. There may be a tidally-disrupted dwarf galaxy at the end of its northern arm.
One supernova has been observed in NGC 986: SN 2018lei (type Ic, mag. 16.8).
References
External links
Barred spiral galaxies
Fornax
0986
Astronomical objects discovered in 1826
009747 | NGC 986 | [
"Astronomy"
] | 340 | [
"Fornax",
"Constellations"
] |
49,287,688 | https://en.wikipedia.org/wiki/Boson%20sampling | Boson sampling is a restricted model of non-universal quantum computation introduced by Scott Aaronson and Alex Arkhipov after the original work of Lidror Troyansky and Naftali Tishby, that explored possible usage of boson scattering to evaluate expectation values of permanents of matrices. The model consists of sampling from the probability distribution of identical bosons scattered by a linear interferometer. Although the problem is well defined for any bosonic particles, its photonic version is currently considered as the most promising platform for a scalable implementation of a boson sampling device, which makes it a non-universal approach to linear optical quantum computing. Moreover, while not universal, the boson sampling scheme is strongly believed to implement computing tasks which are hard to implement with classical computers by using far fewer physical resources than a full linear-optical quantum computing setup. This advantage makes it an ideal candidate for demonstrating the power of quantum computation in the near term.
Description
Consider a multimode linear-optical circuit of N modes that is injected with M indistinguishable single photons (N>M). Then, the photonic implementation of the boson sampling task consists of generating a sample from the probability distribution of single-photon measurements at the output of the circuit. Specifically, this requires reliable sources of single photons (currently the most widely used ones are parametric down-conversion crystals), as well as a linear interferometer. The latter can be fabricated, e.g., with fused-fiber beam splitters, through silica-on-silicon or laser-written integrated interferometers, or electrically and optically interfaced optical chips.
Finally, the scheme also necessitates high efficiency single photon-counting detectors, such as those based on current-biased superconducting nanowires, which perform the measurements at the output of the circuit. Therefore, based on these three ingredients, the boson sampling setup does not require any ancillas, adaptive measurements or entangling operations, as does e.g. the universal optical scheme by Knill, Laflamme and Milburn (the KLM scheme). This makes it a non-universal model of quantum computation, and reduces the amount of physical resources needed for its practical realization.
Specifically, suppose the linear interferometer is described by an N×N unitary matrix which performs a linear transformation of the creation (annihilation) operators of the circuit's input modes:
Here i (j) labels the input (output) modes, and denotes the creation (annihilation) operators of the output modes (i,j=1,..., N). An interferometer characterized by some unitary naturally induces a unitary evolution on -photon states. Moreover, the map is a homomorphism between -dimensional unitary matrices, and unitaries acting on the exponentially large Hilbert space of the system: simple counting arguments show that the size of the Hilbert space corresponding to a system of M indistinguishable photons distributed among N modes is given by the binomial coefficient (notice that since this homomorphism exists, not all values of are possible).
Suppose the interferometer is injected with an input state of single photons with is the number of photons injected into the kth mode). Then, the state at
the output of the circuit can be written down as A simple way to understand the homomorphism between and is the following :
We define the isomorphism for the basis states: ,
and get the following result :
Consequently, the probability of detecting photons at the kth output mode is given as
In the above expression stands for the permanent of the matrix which is obtained from the unitary by repeating times its ith column and times its jth row. Usually, in the context of the boson sampling problem the input state is taken of a standard form, denoted as for which each of the first M modes of the interferometer is injected with a single photon. In this case the above expression reads:
where the matrix is obtained from by keeping its first M columns and repeating times its jth row. Subsequently, the task of boson sampling is to sample either exactly or approximately from the above output distribution, given the unitary describing the linear-optical circuit as input. As detailed below, the appearance of the permanent in the corresponding statistics of single-photon measurements contributes to the hardness of the boson sampling problem.
Complexity of the problem
The main reason of the growing interest towards the model of boson sampling is that despite being non-universal it is strongly believed to perform a computational task that is intractable for a classical computer. One of the main reasons behind this is that the probability distribution, which the boson sampling device has to sample from, is related to the permanent of complex matrices. The computation of the permanent is in the general case an extremely hard task: it falls in the #P-hard complexity class. Moreover, its approximation to within multiplicative error is a #P-hard problem as well.
All current proofs of the hardness of simulating boson sampling on a classical computer rely on the strong computational consequences that its efficient simulation by a classical algorithm would have. Namely, these proofs show that an efficient classical simulation would imply the collapse of the polynomial hierarchy to its third level, a possibility that is considered very unlikely by the computer science community, due to its strong computational implications (in line with the strong implications of P=NP problem).
Exact sampling
The hardness proof of the exact boson sampling problem can be achieved following two distinct paths. Specifically, the first one uses the tools of the computational complexity theory and combines the following two facts:
Approximating the probability of a specific measurement outcome at the output of a linear interferometer to within a multiplicative constant is a #P-hard problem (due to the complexity of the permanent)
If a polynomial-time classical algorithm for exact boson sampling existed, then the above probability could have been approximated to within a multiplicative constant in the BPPNPcomplexity class, i.e. within the third level of the polynomial hierarchy
When combined these two facts along with Toda's theorem result in the collapse of the polynomial hierarchy, which as mentioned above is highly unlikely to occur. This leads to the conclusion that there is no classical polynomial-time algorithm for the exact boson sampling problem.
On the other hand, the alternative proof is inspired by a similar result for another restricted model of quantum computation – the model of instantaneous quantum computing.
Namely, the proof uses the KLM scheme, which says that linear optics with adaptive measurements is universal for the class BQP. It also relies on the following facts:
Linear optics with postselected measurements is universal for PostBQP, i.e. quantum polynomial-time class with postselection (a straightforward corollary of the KLM construction)
The class PostBQP is equivalent to PP (i.e. the probabilistic polynomial-time class): PostBQP = PP
The existence of a classical boson sampling algorithm implies the simulability of postselected linear optics in the PostBPP class (that is, classical polynomial-time with postselection, known also as the class BPPpath)
Again, the combination of these three results, as in the previous case, results in the collapse of the polynomial hierarchy. This makes the existence of a classical polynomial-time algorithm for the exact boson sampling problem highly unlikely.
The best proposed classical algorithm for exact boson sampling runs in time for a system with n photons and m output modes. This algorithm leads to an estimate of 50 photons required to demonstrate quantum supremacy with boson sampling. There is also an open-source implementation in R.
Approximate sampling
The above hardness proofs are not applicable to the realistic implementation of a boson sampling device, due to the imperfection of any experimental setup (including the presence of noise, decoherence, photon losses, etc.). Therefore, for practical needs one necessitates the hardness proof for the corresponding approximate task. The latter consists of sampling from a probability distribution that is close to the one given by , in terms of the total variation distance. The understanding of the complexity of this problem relies then on several additional assumptions, as well as on two yet unproven conjectures.
Specifically, the proofs of the exact boson sampling problem cannot be directly applied here, since they are based on the #P-hardness of estimating the exponentially-small probability of a specific measurement outcome. Thus, if a sampler "knew" which we wanted to estimate, then it could adversarially choose to corrupt it (as long as the task is approximate). That is why, the idea is to "hide" the above probability into an N×N random unitary matrix. This can be done knowing that any M×M submatrix of a unitary , randomly chosen according to the Haar measure, is close in variation distance to a matrix of i.i.d. complex random Gaussian variables, provided that M ≤ N1/6 (Haar random matrices can be directly implemented in optical circuits by mapping independent probability density functions for their parameters, to optical circuit components, i.e., beam splitters and phase shifters). Therefore, if the linear optical circuit implements a Haar random unitary matrix, the adversarial sampler will not be able to detect which of the exponentially
many probabilities we care about, and thus will not be able to avoid its estimation. In this case is proportional to the squared absolute value of the permanent of the M×M matrix of i.i.d. Gaussians, smuggled inside These arguments bring us to the first conjecture of the hardness proof of approximate boson sampling problem – the permanent-of-Gaussians conjecture:
Approximating the permanent of a matrix of i.i.d. Gaussians to within multiplicative error is a #P-hard task.
Moreover, the above conjecture can be linked to the estimation of which the given probability of a specific measurement outcome is proportional to. However to establish this link one has to rely on another conjecture – the permanent anticoncentration conjecture:
There exists a polynomial Q such that for any M and δ>0 the probability over M×M matrices of the following inequality to hold is smaller than δ:
By making use of the above two conjectures (which have several evidences of being true), the final proof eventually states that the existence of a classical polynomial-time algorithm for the approximate boson sampling task implies the collapse of the polynomial hierarchy. It is also worth mentioning another fact important to the proof of this statement, namely the so-called bosonic birthday paradox (in analogy with the well-known birthday paradox). The latter states that if M identical bosons are scattered among N≫M2 modes of a linear interferometer with no two bosons in the same mode, then with high probability two bosons will not be found in the same output mode either. This property has been experimentally observed with two and three photons in integrated interferometers of up to 16 modes. On the one hand this feature facilitates the implementation of a restricted boson sampling device. Namely, if the probability of having more than one photon at the output of a linear optical circuit is negligible, one does not require photon-number-resolving detectors anymore: on-off detectors will be sufficient for the realization of the setup.
Although the probability of a specific measurement outcome at the output of the interferometer is related to the permanent of submatrices of a unitary matrix, a boson sampling machine does not allow its estimation. The main reason behind is that the corresponding detection probability is usually exponentially small. Thus, in order to collect enough statistics to approximate its value, one has to run the quantum experiment for exponentially long time. Therefore, the estimate obtained from a boson sampler is not more efficient that running the classical polynomial-time algorithm by Gurvits for approximating the permanent of any matrix to within additive error.
Variants
Scattershot boson sampling
As already mentioned above, for the implementation of a boson sampling machine one necessitates a reliable source of many indistinguishable photons, and this requirement currently remains one of the main difficulties in scaling up the complexity of the device. Namely, despite recent advances in photon generation techniques using atoms, molecules, quantum dots and color centers in diamonds, the most widely used method remains the parametric down-conversion (PDC) mechanism. The main advantages of PDC sources are the high photon indistinguishability, collection efficiency and relatively simple experimental setups. However, one of the drawbacks of this approach is its non-deterministic (heralded) nature. Specifically, suppose the probability of generating a single photon by means of a PDC crystal is ε. Then, the probability of generating simultaneously M single photons is εM, which decreases exponentially with M. In other words, in order to generate the input state for the boson sampling machine, one would have to wait for exponentially long time, which would kill the advantage of the quantum setup over a classical machine. Subsequently, this characteristic restricted the use of PDC sources to proof-of-principle demonstrations of a boson sampling device.
Recently, however, a new scheme has been proposed to make the best use of PDC sources for the needs of boson sampling, greatly enhancing the rate of M-photon events. This approach has been named scattershot boson sampling, which consists of connecting N (N>M) heralded single-photon sources to different input ports of the linear interferometer. Then, by pumping all N PDC crystals with simultaneous laser pulses, the probability of generating M photons will be given as Therefore, for N≫M, this results in an exponential improvement in the single photon generation rate with respect to the usual, fixed-input boson sampling with M sources. This setting can also be seen as a problem of sampling N two-mode squeezed vacuum states generated from N PDC sources.
Scattershot boson sampling is still intractable for a classical computer: in the conventional setup we fixed the columns that defined our M×M submatrix and only varied the rows, whereas now we vary the columns too, depending on which M out of N PDC crystals generated single photons. Therefore, the proof can be constructed here similar to the original one. Furthermore, scattershot boson sampling has been also recently implemented with six photon-pair sources coupled to integrated photonic circuits of nine and thirteen modes, being an important leap towards a convincing experimental demonstration of the quantum computational supremacy. The scattershot boson sampling model can be further generalized to the case where both legs of PDC sources are subject to linear optical transformations (in the original scattershot case, one of the arms is used for heralding, i.e., it goes through the identity channel). Such a twofold scattershot boson sampling model is also computationally hard, as proven by making use of the symmetry of quantum mechanics under time reversal.
Gaussian boson sampling
Another photonic implementation of boson sampling concerns Gaussian input states, i.e. states whose quasiprobability Wigner distribution function is a Gaussian one. The hardness of the corresponding sampling task can be linked to that of scattershot boson sampling. Namely, the latter can be embedded into the conventional boson sampling setup with Gaussian inputs. For this, one has to generate two-mode entangled Gaussian states and apply a Haar-random unitary to their "right halves", while doing nothing to the others. Then we can measure the "left halves" to find out which of the input states contained a photon before we applied This is precisely equivalent to scattershot boson sampling, except for the fact that our measurement of the herald photons has been deferred till the end of the experiment, instead of happening at the beginning. Therefore, approximate Gaussian boson sampling can be argued to be hard under precisely the same complexity assumption as can approximate ordinary or scattershot boson sampling. Gaussian resources can be employed at the measurement stage, as well. Namely, one can define a boson sampling model, where a linear optical evolution of input single-photon states is concluded by Gaussian measurements (more specifically, by eight-port homodyne detection that projects each output mode onto a squeezed coherent state). Such a model deals with continuous-variable measurement outcome, which, under certain conditions, is a computationally hard task. Finally, a linear optics platform for implementing a boson sampling experiment where input single-photons undergo an active (non-linear) Gaussian transformation is also available. This setting makes use of a set of two-mode squeezed vacuum states as a prior resource, with no need of single-photon sources or in-line nonlinear amplification medium. This variant uses the Hafnian, a generalization of the permanent.
Classically simulable boson sampling tasks
The above results state that the existence of a polynomial-time classical algorithm for the original boson sampling scheme with indistinguishable single photons (in the exact and approximate cases), for scattershot, as well as for the general Gaussian boson sampling problems is highly unlikely. Nevertheless, there are some non-trivial realizations of the boson sampling problem that allow for its efficient classical simulation. One such example is when the optical circuit is injected with distinguishable single photons. In this case, instead of summing the probability amplitudes corresponding to photonic many-particle paths, one has to sum the corresponding probabilities (i.e. the squared absolute values of the amplitudes). Consequently, the detection probability will be proportional to the permanent of submatrices of (component-wise) squared absolute value of the unitary The latter is now a non-negative matrix. Therefore, although the exact computation of the corresponding permanent is a #P-complete problem, its approximation can be performed efficiently on a classical computer, due to the seminal algorithm by Jerrum, Sinclaire and Vigoda.
In other words, approximate boson sampling with distinguishable photons is efficiently classically simulable.
Another instance of classically simulable boson sampling setups consists of sampling from the probability distribution of coherent states injected into the linear interferometer. The reason is that at the output of a linear optical circuit coherent states remain such, and do not create any quantum entanglement among the modes. More precisely, only their amplitudes are transformed, and the transformation can be efficiently calculated on a classical computer (the computation comprises matrix multiplication). This fact can be used to perform corresponding sampling tasks from another set of states: so-called classical states, whose Glauber-Sudarshan P function is a well-defined probability distribution. These states can be represented as a mixture of coherent states due to the optical equivalence theorem. Therefore, picking random coherent states distributed according to the corresponding P function, one can perform efficient classical simulation of boson sampling from this set of classical states.
Experimental implementations
The above requirements for the photonic boson sampling machine allow for its small-scale construction by means of existing technologies. Consequently, shortly after the theoretical model was introduced, four different groups
simultaneously reported its realization.
Specifically, this included the implementation of boson sampling with:
two and three photons scattered by a six-mode linear unitary transformation (represented by two orthogonal polarizations in 3×3 spatial modes of a fused-fiber beam splitter) by a collaboration between the University of Queensland and MIT
three photons in different modes of a six-mode silica-on-silicon waveguide circuit, by a collaboration between Universities of Oxford, Shanghai, London and Southampton
three photons in a femtosecond laser-written five-mode interferometer, by a collaboration between universities of Vienna and Jena
three photons in a femtosecond laser-written five-mode interferometer implementing a Haar-random unitary transformation, by a collaboration between Milan's Institute of Photonics and Nanotechnology, Universidade Federal Fluminense and Sapienza University of Rome.
Later on, more complex boson sampling experiments have been performed, increasing the number of spatial modes of random interferometers up to 13 and 9 modes, and realizing a 6-mode fully reconfigurable integrated circuit.
These experiments altogether constitute the proof-of-principle demonstrations of an operational boson sampling device, and route towards its larger-scale implementations.
Implementation of scattershot boson sampling
A first scattershot boson sampling experiment has been recently implemented using six photon-pair sources coupled to integrated photonic circuits with 13 modes. The 6 photon-pair sources were obtained via type-II PDC processes in 3 different nonlinear crystals (exploiting the polarization degree of freedom). This allowed to sample simultaneously between 8 different input states. The 13-mode interferometer was realized by femtosecond laser-writing technique on alumino-borosilicate glas.
This experimental implementation represents a leap towards an experimental demonstration of the quantum computational supremacy.
Proposals with alternative photonic platform
There are several other proposals for the implementation of photonic boson sampling. This includes, e.g., the scheme for arbitrarily scalable boson sampling using two nested fiber loops. In this case, the architecture employs time-bin encoding, whereby the incident photons form a pulse train entering the loops. Meanwhile, dynamically controlled loop coupling ratios allow the construction of arbitrary linear interferometers. Moreover, the architecture employs only a single point of interference and may thus be easier to stabilize than other implementations.
Another approach relies on the realization of unitary transformations on temporal modes based on dispersion and pulse shaping. Namely, passing consecutively heralded photons through time-independent dispersion and measuring the output time of the photons is equivalent to a boson sampling experiment. With time-dependent dispersion, it is also possible to implement arbitrary single-particle unitaries. This scheme requires a much smaller number of sources and detectors and do not necessitate a large system of beam splitters.
Certification
The output of a universal quantum computer running, for example, Shor's factoring algorithm, can be efficiently verified classically, as is the case for all problems in
the non-deterministic polynomial-time (NP) complexity class. It is however not clear that a similar structure
exists for the boson sampling scheme. Namely, as the latter is related to the problem of estimating matrix permanents (falling into #P-hard complexity class), it is not understood how to verify correct operation for large versions of the setup. Specifically, the naive verification of the output of a boson sampler by computing the corresponding measurement probabilities represents a problem intractable for a classical computer.
A first relevant question is whether it is possible or not to distinguish between uniform and boson-sampling distributions by performing a polynomial number of measurements. The initial argument introduced in Ref. stated that as long as one makes use of symmetric measurement settings the above is impossible (roughly speaking a symmetric measurement scheme does not allow for labeling the output modes of the optical circuit). However, within current technologies the assumption of a symmetric setting is not justified (the tracking of the measurement statistics is fully accessible), and therefore the above argument does not apply. It is then possible to define a rigorous and efficient test to discriminate the boson sampling statistics from an unbiased probability distribution. The corresponding discriminator is correlated to the permanent of the submatrix associated with a given measurement pattern, but can be efficiently calculated. This test has been applied experimentally to distinguish between a boson sampling and a uniform distribution in the 3-photon regime with integrated circuits of 5, 7, 9 and 13 modes.
The test above does not distinguish between more complex distributions, such as quantum and classical, or between fermionic and bosonic statistics. A physically motivated scenario to be addressed is the unwanted introduction of distinguishability between photons, which destroys quantum interference (this regime is readily accessible experimentally, for example by introducing temporal delay between photons). The opportunity then exists to tune between ideally indistinguishable (quantum) and perfectly distinguishable (classical) data and measure the change in a suitably constructed metric. This scenario can be addressed by a statistical test which performs a one-on-one likelihood comparison of the output probabilities. This test requires the calculation of a small number of permanents, but does not need the calculation of the full expected probability distribution. Experimental implementation of the test has been successfully reported in integrated laser-written circuits for both the standard boson sampling (3 photons in 7-, 9- and 13-mode interferometers) and the scattershot version (3 photons in 9- and 13-mode interferometers with different input states). Another possibility is based on the bunching property of indinguishable photons. One can analyze the probability to find a k-fold coincidence measurement outcomes (without any multiply populated input mode), which is significantly higher for distinguishable particles than for bosons due to the bunching tendency of the latters. Finally, leaving the space of random matrices one may focus on specific multimode setups with certain features. In particular, the analysis of the effect of bosonic clouding (the tendency for bosons to favor events with all particles in the same half of the output array of a continuous-time many-particle quantum walk) has been proven to discriminate the behavior of distinguishable and indistinguishable particles in this specific platform.
A different approach to confirm that the boson sampling machine behaves as the theory predicts is to make use of fully reconfigurable optical circuits. With large-scale single-photon and multiphoton interference verified with predictable multimode correlations in a fully characterized circuit, a reasonable assumption is that the system maintains correct operation as the circuit is continuously reconfigured to implement a random unitary operation. To this end, one can exploit quantum suppression laws (the probability of specific input-output combinations is suppressed when the linear interferometer is described by a Fourier matrix or other matrices with relevant symmetries). These suppression laws can be classically predicted in efficient ways. This approach allows also to exclude other physical models, such as mean-field states, which mimic some collective multiparticle properties (including bosonic clouding). The implementation of a Fourier matrix circuit in a fully reconfigurable 6-mode device has been reported, and experimental observations of the suppression law have been shown for 2 photons in 4- and 8-mode Fourier matrices.
Alternative implementations and applications
Apart from the photonic realization of the boson sampling task, several other setups have been proposed. This includes, e.g., the encoding of bosons into the local transverse phonon modes of trapped ions. The scheme allows deterministic preparation and high-efficiency readout of the corresponding phonon Fock states and universal manipulation of the phonon modes through a combination of inherent Coulomb interaction and individual phase shifts. This scheme is scalable and relies on the recent advances in ion trapping techniques (several dozens of ions can be successfully trapped, for example, in linear Paul traps by making use of anharmonic axial potentials).
Another platform for implementing the boson sampling setup is a system of interacting spins: recent observation show that boson sampling with M particles in N modes is equivalent to the short-time evolution with M excitations in the XY model of 2N spins. One necessitates several additional assumptions here, including small boson bunching probability and efficient error postselection. This scalable scheme, however, is rather promising, in the light of considerable development in the construction and manipulation of coupled superconducting qubits and specifically the D-Wave machine.
The task of boson sampling shares peculiar similarities with the problem of determining molecular vibronic spectra: a feasible modification of the boson sampling scheme results in a setup that can be used for the reconstruction of a molecule's Franck–Condon profiles (for which no efficient classical algorithm is currently known). Specifically, the task now is to input specific squeezed coherent states into a linear interferometer that is determined by the properties of the molecule of interest. Therefore, this prominent observation makes the interest towards the implementation of the boson sampling task to get spread well beyond the fundamental basis.
It has also been suggested to use a superconducting resonator network Boson Sampling device as an interferometer. This application is assumed to be practical, as small changes in the couplings between the resonators will change the sampling results. Sensing of variation in the parameters capable of altering the couplings is thus achieved, when comparing the sampling results to an unaltered reference.
Variants of the boson sampling model have been used to construct classical computational algorithms, aimed, e.g., at the estimation of certain matrix permanents (for instance, permanents of positive-semidefinite matrices related to the corresponding open problem in computer science) by combining tools proper to quantum optics and computational complexity.
Coarse-grained boson sampling has been proposed as a resource of decision and function problems that are computationally hard, and may thus have cryptographic applications. The first related proof-of-principle experiment was performed with a photonic boson-sampling machine (fabricated by a direct femtosecond laser-writing technique), and confirmed many of the theoretical predictions.
Gaussian boson sampling has been analyzed as a search component for computing binding propensity between molecules of pharmacological interest as well.
See also
Quantum random circuits
Cross-entropy benchmarking
Linear optical quantum computing
KLM protocol
References
External links
QUCHIP project
Quantum Information Lab – Sapienza: video on boson sampling
Quantum Information Lab – Sapienza: video on scattershot boson sampling
The Qubit Lab – Boson Sampling
Quantum information science
Quantum optics
Quantum algorithms | Boson sampling | [
"Physics"
] | 6,232 | [
"Quantum optics",
"Quantum mechanics"
] |
49,287,862 | https://en.wikipedia.org/wiki/Meso-Zeaxanthin | Meso-zeaxanthin (3R,3′S-zeaxanthin) is a xanthophyll carotenoid, and is one of the three stereoisomers of zeaxanthin. The meso- form is the second most abundant in nature, after 3R,3′R-zeaxanthin, which is produced by plants and algae. Meso-zeaxanthin has been identified in specific tissues of marine organisms and in the macula lutea, also known as the "yellow spot" of the human retina.
Occurrence
Carotenoids are essential for animal health and functioning, but animals cannot produce them. Animals obtain carotenoids from their diet, with herbivores sourcing them from plants or algae, and carnivores, in turn, sourcing them from herbivores.
Meso-zeaxanthin is not present in plants, except for marine species. Originally, it was suggested that meso-zeaxanthin present in humans and other vertebrates was non-dietary in origin, instead being biosynthesized in the macula (the central part of the retina) from retinal lutein (another xanthophyll carotenoid found in the human diet); this work has since been refuted.
Consistent with work by Maoka et al. in 1986, Nolan et al. showed that meso-zeaxanthin is present in the skin of trout, sardine and salmon, and in the flesh of trout. In a subsequent publication, Nolan's group detected and quantified the three stereoisomers of zeaxanthin, including meso-zeaxanthin, in the flesh of two different trout species, which was the first report of concentrations of meso-zeaxanthin in habitually consumed food. Prior to this research, a publication from Khachick et al. (2002) reported that liver from Japanese quail (Coturnix japonica) and frog plasma contain meso-zeaxanthin.
Meso-zeaxanthin may be generated from other carotenoids consumed by animals, as carotenoids can be interconverted for functional reasons. For example, it has been suggested that meso-zeaxanthin of trout integuments is derived from astaxanthin, and meso-zeaxanthin in primates is derived at least in part from lutein.
A few commercially available food supplements include meso-zeaxanthin in their formulations, supposedly to support macular health. A 2016 study comparing the carotenoid concentrations of commercially available food supplements on their label found that, while only two declared their inclusion of meso-zeaxanthin, it was present in several others as well. The authors concluded that the presence of meso-zeaxanthin in the other formulations was likely due to it being less expensive than zeaxanthin, and it is hard to distinguish from one from the other via chemical analysis.
In the macula
Meso-zeaxanthin, lutein, and 3R,3′R-zeaxanthin are the main carotenoids in the macula lutea, found in a ratio of 1:1:1, and are collectively referred to as macular pigment (MP). Meso-zeaxanthin is concentrated at the epicentre of the macula, where it accounts for around 50% of MP at this location, with lutein dominating the peripheral macula.
Uses
As an antioxidant and short-wavelength light filter
Of the three macular carotenoids (lutein, zeaxanthin and meso-zeaxanthin), meso-zeaxanthin is the most powerful antioxidant, but a combination of the macular carotenoids has been shown to exhibit the greatest antioxidant potential when compared to the individual carotenoids at the same total concentration. This may explain why the human macula uniquely contains these three carotenoids out of about 700 carotenoids present in nature. Also, it has been shown that the combination of the carotenoids results in optimal light filtration (i.e., filtration of short-wavelength blue light) at the macula. This is important because short-wavelength light incident at the macula causes chromatic aberration and light scattering, phenomena that adversely affect visual function and result in poor contrast sensitivity.
Use in supplements aimed at eye health
In 2013, the Age-Related Eye Disease Study 2 (AREDS2) reported a reduced risk of visual loss and a reduced risk of disease progression over 5 years in 4,200 participants with early or moderate age-related macular degeneration (AMD) who were supplemented with a formulation containing the macular carotenoids and co-antioxidants. The AREDS2 preparation contained only two of the macular pigment’s three carotenoids (lutein and 3R,3´R-zeaxanthin), and did not include meso-zeaxanthin, which is the dominant carotenoid at the centre of the macula, the presence of which is essential for maximum collective antioxidant effect.
Studies have shown that the addition of meso-zeaxanthin to formulations used to increase MP and enhance visual function in diseased and healthy retinas has proven effective. Trials have shown that a formulation containing all three macular carotenoids in a meso-zeaxanthin:lutein:zeaxanthin (mg) ratio of 10:10:2 is superior to alternative formulations, in terms of visual improvements and in observed increases in MP.
Use in poultry industries
Broiler chickens are yellow when they are fed with carotenoid-containing feed, as these carotenoids accumulate in the skin and subcutaneous fat of the animal. Carotenoid deposition is also the cause of the yellow colour of egg yolk. For this reason, poultry producers add carotenoids (typically lutein, zeaxanthin, canthaxanthin, and β-apo-8´-apocarotenal) to the feed to increase the attractiveness of the final product for the consumer, but also to support animal health. It is believed that lutein and zeaxanthin act synergistically to increase the yellow hue, whereas zeaxanthin is more powerful than lutein due to its larger chromophore. Therefore, several companies use marigold extract where a percentage of lutein has been converted into meso-zeaxanthin in order to supplement broilers and hens with both carotenoids. The isomer of zeaxanthin obtained from lutein is meso-zeaxanthin due to the nature of the technique used (see below).
Production
Meso-zeaxanthin is produced at an industrial level from the lutein obtained from marigold petals. The process involves saponification, which is carried out using high temperature and a high concentration of base, leads to the isomerization of the 4′-5′ double bond to the 5′-6′ position. This converts the ɛ-ring of lutein into a β-ring, thus converting lutein into meso-zeaxanthin. The stereochemistry of this zeaxanthin is determined by the position of the hydroxyl group at the 3´ position, which results in the "S" designation for the final zeaxanthin molecule. The stereoisomer produced by this process is 3R,3′S-zeaxanthin (i.e., meso-zeaxanthin). The conditions of saponification can be modulated to increase or decrease the conversion rate of lutein into meso-zeaxanthin.
Animal studies
Meso-zeaxanthin has been tested for animal toxicity by several research teams, who report a lack of toxicity. The NOAEL ('No Observed-Adverse-Effect Level') of meso-zeaxanthin is far greater than doses used in dietary supplements. In 2016, the GRAS ('Generally Regarded As Safe') status of meso-zeaxanthin was acknowledged by the FDA.
Human studies
Meso-zeaxanthin is a regular dietary component in countries where it is a major pigment used by the poultry industry, particularly in Mexico. Neither adverse nor positive effects have yet been reported. In addition, meso-zeaxanthin has been tested for efficacy, though not for safety, in small pilot studies in humans.
The first study to evaluate the effects of a dietary supplement containing predominantly meso-zeaxanthin was conducted in 2007. This research confirmed that meso-zeaxanthin was effectively absorbed into the serum, and MP density was increased significantly in the supplementation group. No such increases were observed in the placebo group.
In another study 19 subjects consumed a supplement composed of all three macular carotenoids, including meso-zeaxanthin, for 22 days. Results demonstrated that meso-zeaxanthin was absorbed. At the Institute of Vision Research, Waterford Institute of Technology, the Meso-zeaxanthin Ocular Supplementation Trials (MOST), have been conducted to evaluate safety, MP response, and serum carotenoid response in subjects with and without AMD, following consumption of a supplement containing all three macular carotenoids in which meso-zeaxanthin was predominant. These studies confirmed safety for human consumption of the macular carotenoids following many biological tests to assess renal and liver functions, lipid profile, hematologic profile, and markers of inflammation.
Also, the MOST trials identified statistically significant increases in serum concentrations of meso-zeaxanthin and lutein from baseline. Significant increases in central MP levels were also observed after just two weeks of supplementation. Furthermore, in patients who had an atypical MP distribution in the eye (i.e., they did not have a high concentration of pigment in the centre of the macula), when supplemented with a meso-zeaxanthin-dominant supplement for 8 weeks, the normal pigment profile was reinstated, whereas this was not the case when patients were supplemented with a formulation lacking meso-zeaxanthin.
The main findings from the MOST trials in patients with AMD were published in 2013 and 2015. The series of publications from these trials concluded, "Augmentation of the MP optical density across its spatial profile and enhancements in contrast sensitivity were best achieved after supplementation with a formulation containing high doses of meso-zeaxanthin in combination with lutein and zeaxanthin". Also, the final publication from this work, published in 2015, concluded that, "The inclusion of meso-zeaxanthin in a supplement formulation seems to confer benefits in terms of MP augmentation and in terms of enhanced contrast sensitivity in subjects with early AMD.".
In 2016 and 2017, the results of two small clinical trials were published. The first trial, the CREST (Central Retinal Enrichment Supplementation Trials) study involved 105 normal healthy volunteers who underwent a series of complex tests of vision and were supplemented over 12 months. Of these volunteers, 53 received daily active supplements containing meso-zeaxanthin, lutein, and zeaxanthin, while 52 subjects received a placebo (the control group). The outcome demonstrated that those receiving all three macular carotenoids had improved contrast sensitivity.
The second trial, CREST AMD, was a two-year trial involving 96 subjects diagnosed with the early stages of AMD. All subjects received the AREDS2-recommended formula, with or without added meso-zeaxanthin, and all showed a significant improvement in the primary outcome measure of contrast sensitivity when reading an eye-chart. There was no difference between the results for subjects whose supplements included meso-zeaxanthin versus those who did not; thus, meso-zeaxanthin did not improve the eye health of the subjects who took it. There were no significant differences in how the subjects' AMD progressed, between the meso-zeaxanthin group and the AREDS2 group.
See also
Stereoisomerism
References
Carotenoids
Cyclohexenes | Meso-Zeaxanthin | [
"Biology"
] | 2,584 | [
"Biomarkers",
"Carotenoids"
] |
65,830,519 | https://en.wikipedia.org/wiki/Mostafa%20Roustaei | Mostafa Roustaei () is an Iranian amateur astronomer and retired fighter pilot who flew with Grumman F-14 Tomcat during the Iran–Iraq War. French military historian Pierre Razoux has credited him with 5 aerial victories, a record that qualifies him as a flying ace.
Career
Roustaei was hired by the IIAF in 1970 and after 30 years of service, he was retired with the rank of colonel. He served for some time as the chief operations officer of the 6th Tactical Fighter Base. A U.S. trained pilot, he graduated from the AETC course at Laughlin Air Force Base in 1974. He was subsequently certified with F-4D/E Phantom II, an aircraft he flew for 2200 hours before switching to F-14 Tomcat. He flew a further 2086 hours with the latter.
Aerial victories
According to aviation author Kash Ryan, Roustaei's aerial victories verified by his logbooks and corroborated with other accounts include four using AIM-54 Phoenix missiles and one maneuver kill, against two MiG-23s, a MiG-21 and a pair of Dassault Mirage F1s. The details are as follows:
See also
List of Iranian flying aces
References
Iran–Iraq War flying aces
Iranian flying aces
Living people
Islamic Republic of Iran Army colonels
1951 births
Amateur astronomers
Islamic Republic of Iran Army personnel of the Iran–Iraq War
Islamic Republic of Iran Air Force personnel | Mostafa Roustaei | [
"Astronomy"
] | 298 | [
"Astronomers",
"Amateur astronomers"
] |
65,830,865 | https://en.wikipedia.org/wiki/Mirror%20tree | In genealogy, a mirror tree is a family tree reconstructed through estimates of consanguinity.
References
Family trees
Genetics | Mirror tree | [
"Biology"
] | 25 | [
"Genetics"
] |
65,831,482 | https://en.wikipedia.org/wiki/Expatriate%20social%20capital | Social capital is the product of human interactions and relationships, which occur between individuals and social networks. Therefore, it can be summarized as the shared links, understandings and values that allow individuals and groups to trust each other, and therefore, to work with each other in society.
In the case of expatriation—the process through which an individual lives and works in a country other than their country of citizenship, often temporarily and for work reasons—, social capital has been identified as an important factor for expatriate career success, performance, cultural and psychological adjustment, and international knowledge transfers, among other topics.
General definitions of social capital
Given the long history of the social capital concept, a range of definitions have emerged over the years, especially since the topic gained more prominence in the 1990s. Still, the most cited definitions in 2019 belonged to Pierre Bourdieu, Robert Putnam, Nan Lin, James Coleman, and Janine Nahapiet and Sumantra Ghoshal. The table below shows some of the definitions these authors put forward:
Expatriate social capital in International Human Resource Management
Social resources theory
According to social resources theory, there are a number of resources embedded in a person's social network and social ties, including material goods and intangible items—for instance, trust, values, or status. In this way, individuals can benefit from their social ties and use them as resources when they are able to receive information and support through them to achieve certain goals and objectives.
Expatriate social capital is distinct from other forms of social capital because it usually involves social connections across a range of different countries. Additionally, it has especial relevance for International Human Resource Management (IHRM) because it can be viewed as a resource, not only useful for expatriates themselves, but also for the multinational companies and enterprises (MNCs and MNEs) employing them.
Business expatriates
Historically, the use of the term expatriate has been inconsistent and varied. For this reason, it is important to know that IHRM concerns a specific type of expatriate: the business expatriate. According to McNulty and Brewster, who argued that a concise and universal definition should be adopted, business expatriates are “legally working individuals who reside temporarily in a country of which they are not a citizen in order to accomplish a career-related goal, being relocated abroad either by an organization, by self-initiation or directly employed within the host-country”.
Organizational knowledge benefits of expatriate social capital.
Needless to say, individuals can share their resources with others. In the case of expatriates, they can transfer the knowledge they earned through their social resources during international experiences to the organizations they work for. As a result, organizations can leverage expatriate social capital to improve inter-unit learning inside the firm, learn about external business opportunities, train other personnel (such as future expatriates and/or leaders) and gain a competitive advantage in the international economy.
Transfer of inpatriate and repatriate social capital
For instance, if an inpatriate (a kind of expatriate who is from a foreign country, but is transferred from a foreign subsidiary to the corporation's headquarters; Harvey, Novicevic and Speier, 1999) has large social networks in the host country, it will be positively related to firm-specific learning.
Similarly, research carried out with expatriates after an international assignment (usually called repatriates) also suggests that the benefits of the social ties developed abroad exceeds the period of the assignment, facilitating knowledge flows across units in an organization.
References
Interpersonal relationships
Human communication | Expatriate social capital | [
"Biology"
] | 762 | [
"Human communication",
"Behavior",
"Interpersonal relationships",
"Human behavior"
] |
65,832,522 | https://en.wikipedia.org/wiki/RS%20Canum%20Venaticorum | RS Canum Venaticorum is a binary star system in the northern constellation of Canes Venatici. It serves as the prototype to the class of RS Canum Venaticorum variables. The peak apparent visual magnitude of this system is below the level needed to observe it with the naked eye. It is located at a distance of approximately 443 light years from the Sun based on parallax, but is drifting closer with a net radial velocity of −14 km/s. Olin J. Eggen (1991) included this system as a member of the IC 2391 supercluster, but it was later excluded.
Variability
The variable nature of RS Canum Venaticorum was discovered by the Russian astronomer Lidiya Tseraskaya in 1914. It is a detached binary in a close, circular orbit with a period of 4.8 days. The orbital plane is inclined by an angle of 85.55° to the line of sight from the Earth, causing this to be viewed from Earth as an eclipsing binary. Some of the brightness variations are caused by large spots on the surface of the star. Similar variable stars are known as RS Canum Venaticorum variables.
Some RS Canum Venaticorum variables, including this star, also undergo eclipses. The primary eclipse minimum decreases the visual brightness of the system by 1.21 magnitudes, while the secondary minimum decreases it by 0.26 magnitudes. The exact magnitudes vary somewhat due to the inherent variability of the secondary. The General Catalogue of Variable Stars lists magnitude 8.19 for the secondary minimum and 9.14 for the primary minimum.
Components
The primary component is a relatively inactive F-type main-sequence star with a stellar classification of F5V. It has 2.1 times the radius of the Sun with a projected rotational velocity of about 11 km/s. That rate is slower than expected if the rotation of the star were locked with its orbital period. It has an estimated age of 2.5 billion years.
The secondary component is a magnetically active K-type subgiant star with a class of K2 IV. It has 4.3 times the Sun's radius and a relatively high rotation rate with a projected rotational velocity of 42 km/s. This rapid spin was likely driven by interaction with the primary, and it generates the surface magnetic activity that makes the star variable. As with the Sun, it is undergoing differential rotation.
Lower temperature starspots cover a significant fraction of the secondary's surface, causing light variation as the star rotates. These are found at several active latitudes on the star below 70°, and appear to migrate at the rate of 0.1° per day. The total amount of spots varies in intensity with a cycle of , ranging from 17% to 37% coverage of the surface. The luminosity also varies slightly (0.01) due to proximity and reflection from the primary star. X-ray emission has been detected from this star with a luminosity of . It has also been detected in the radio band.
References
Further reading
F-type main-sequence stars
K-type subgiants
Eclipsing binaries
RS Canum Venaticorum variables
Astronomical X-ray sources
Canes Venatici
BD-36 2344
9430
114519
064293
Canum Venaticorum, RS
TIC objects | RS Canum Venaticorum | [
"Astronomy"
] | 694 | [
"Astronomical X-ray sources",
"Canes Venatici",
"Astronomical objects",
"Constellations"
] |
65,832,994 | https://en.wikipedia.org/wiki/Apeirophobia | Apeirophobia (from ) is the phobia of infinity or eternity, causing discomfort and sometimes panic attacks. It normally starts in adolescence or earlier and it is currently not known how it normally develops over time. Apeirophobia may be caused by existential dread about eternal life or oblivion following death. Due to this, it is often connected with thanatophobia (fear of dying). Like other phobias, apeirophobia may be tied to mental health conditions such as anxiety disorders or obsessive-compulsive disorder.
There is very little research on this phobia. Despite not being recognized specifically by the American Psychiatric Association in the DSM-5, it does meet their criteria for a specific phobia, which is a type of anxiety disorder. There are no known treatment methods that are specifically designed to treat apeirophobia.
If thought of as a form of existential anxiety, apeirophobia might successfully be approached through the lens of existential therapy and the works of existential philosophers and psychologists such as Kierkegaard, Nietzsche, Camus, Sartre, Heidegger and Frankl. Tillich's ontology of courage and Kierkegaard's analysis of anxiety offer approaches to existential anxiety grounded in religious metaphysics, whereas Frankl's logotherapy is non-theistic and focused on the acquisition of personal meaning. Life-negating systems such as Theravada Buddhism may help one seeking oblivion or non-rebirth after death, whereas life-affirming systems such as Nietzscheism may be suitable for those who perceive life as eternal or endlessly repeating.
See also
Existential angst and dread
Meganumerophobia
References
Phobias
Infinity | Apeirophobia | [
"Mathematics"
] | 351 | [
"Mathematical objects",
"Infinity"
] |
65,834,550 | https://en.wikipedia.org/wiki/Automation%20in%20construction | Automation in construction is the combination of methods, processes, and systems that allow for greater machine autonomy in construction activities. Construction automation may have multiple goals, including but not limited to, reducing jobsite injuries, decreasing activity completion times, and assisting with quality control and quality assurance. Some systems may be fielded as a direct response to increasing skilled labor shortages in some countries. Opponents claim that increased automation may lead to less construction jobs and that software leaves heavy equipment vulnerable to hackers.
Research insights on this subject are today published in several jurnals such as Automation in Construction by Elsevier.
Transportation Construction
Kratos Defense & Security Solutions fielded the world’s first Autonomous Truck-Mounted Attenuator (ATMA) in 2017, in conjunction with Royal Truck & Equipment.
Uses of Automation in Construction
Equipment control and management: Automation can be used to control and monitor construction equipment, such as cranes, excavators, and bulldozers.
Material handling: Automated systems can be used to handle, transport, and place materials such as concrete, bricks, and stones.
Surveying: Automated survey equipment and drones can be used to collect and analyze data on construction sites.
Quality control: Automated systems can be used to monitor and control the quality of materials and construction processes.
Safety management: Automated systems can be used to monitor and control safety conditions on construction sites.
Scheduling and planning: Automated systems can be used to manage schedules, resources, and costs.
Waste management: Automated systems can be used to manage and dispose of waste materials generated during construction.
3D printing: Automated 3D printing can be used to create prototypes, models, and even full-scale building components.
Benefits of Automation in Construction
The use of automation in construction has become increasingly prevalent in recent years due to its numerous benefits. Automation in construction refers to the use of machinery, software, and other technologies to perform tasks that were previously done manually by workers.
One of the most significant benefits of automation in construction is increased productivity. Automation can help speed up construction processes, reduce project completion times, and improve overall efficiency. For example, using automated machinery for tasks such as concrete pouring, bricklaying, and welding can significantly increase the speed and accuracy of these tasks, allowing for more work to be completed in a shorter amount of time.
Another benefit of automation in construction is improved safety. By automating tasks that are hazardous to workers, such as demolition or working at height, companies can reduce the risk of accidents and injuries on site. Automation can also help to reduce worker fatigue, which can be a significant factor in accidents and mistakes.
Overall, the use of automation in construction can improve productivity, reduce costs, increase safety, and improve the quality of construction projects. As technology continues to advance, the use of automation is likely to become even more prevalent in the construction industry.
References
Automation in construction
Internet of things
Machine learning
Applications of artificial intelligence
Heavy equipment
Self-driving cars | Automation in construction | [
"Engineering"
] | 588 | [
"Self-driving cars",
"Machine learning",
"Automation",
"Automotive engineering",
"Automation in construction",
"Construction",
"Artificial intelligence engineering"
] |
65,834,584 | https://en.wikipedia.org/wiki/Khristianovich%20Institute%20of%20Theoretical%20and%20Applied%20Mechanics | Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the RAS, ITAM SB RAS () is a research institute in Akademgorodok of Novosibirsk, Russia. It was founded in 1957.
History
The institute was founded by Sergey Khristianovich in 1957, he also became its first director. In 1957, the institute was located within the territory of SibNIA, where it was engaged in the creation of a supersonic wind tunnel until 1960.
In 1991, the International Center for Aerophysical Research (ICAR) was established at the institute. In 1997, the institute became a member of the International Supersonic Tunnel Association (STAI).
In 2005, the institute was named after Sergey Khristianovich.
As of 2023, three scientists at the institute had been arrested on suspicion of treason of sharing hypersonic technology.
Scientific activity
The main directions of scientific research are physical-chemical mechanics, aerogasdynamics, mathematical modeling in mechanics, mechanics of rigid body, deformations, and destructions.
Magazines
Combustion, Explosion, and Shock Waves (together with the SB RAS, LIH SB RAS, ICKC SB RAS)
Prikladnaya Mekhanika i Tekhnicheskaya Fizika (together with the SB RAS, LIH SB RAS)
Teplofizika i Aeromekhanika (together with the SB RAS, IT SB RAS)
Fizicheskaya Mezomekhanika (together with the SB RAS, ISPMS SB RAS)
Notable employees
Vladimir Aniskin is a miniature sculptor, Senior Researcher at the ITAM SB RAS, Guinness World Record Holder.
Branches
Tyumen Division of Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the RAS
Pilot Plant, it is located in ObGES Microdistrict of Novosibirsk
Bibliography
References
Research institutes in Novosibirsk
Research institutes established in 1957
Mechanical engineering organizations
Aerospace engineering organizations
Sovetsky District, Novosibirsk
Research institutes in the Soviet Union
1957 establishments in the Soviet Union | Khristianovich Institute of Theoretical and Applied Mechanics | [
"Engineering"
] | 424 | [
"Aerospace engineering organizations",
"Aeronautics organizations",
"Mechanical engineering organizations",
"Mechanical engineering",
"Aerospace engineering"
] |
65,835,438 | https://en.wikipedia.org/wiki/Biological%20Invasions | Biological Invasions is a peer-reviewed scientific journal on invasion biology published by Springer Science+Business Media.
Abstracting and indexing
The journal is abstracted and indexed in Scopus and the Science Citation Index Expanded. According to the Journal Citation Reports, the journal has a 2020 impact factor of 3.133.
References
External links
Ecology journals | Biological Invasions | [
"Environmental_science"
] | 68 | [
"Environmental science journals",
"Ecology journals",
"Environmental science journal stubs"
] |
65,835,683 | https://en.wikipedia.org/wiki/Gunsight%20Butte | Gunsight Butte is a sandstone summit located in Glen Canyon National Recreation Area, in Kane County of southern Utah. It is situated northeast of the town of Page. Gunsight Butte is an island that towers nearly above Lake Powell when the lake is full. This iconic landmark of the Lake Powell area is a butte composed primarily of Entrada Sandstone, similar to Padres Butte to the east-southeast, and Dominguez Butte to the southeast. The Entrada Sandstone of Gunsight Butte is overlain by Romana Sandstone, and capped by Morrison Formation. The Entrada Sandstone, which was originally deposited as sandy mud on a tidal flat, is believed to have formed about 160 million years ago during the Jurassic period as a giant sand sea, the largest in Earth's history. According to the Köppen climate classification system, Gunsight Butte is located in an arid climate zone with hot, very dry summers, and chilly winters with very little snow.
See also
Colorado Plateau
List of rock formations in the United States
Gallery
References
External links
Weather forecast: National Weather Service
Gunsight Butte prior to Lake Powell: Aerial photo
Photo of east aspect by Barry Goldwater
Colorado Plateau
Landforms of Kane County, Utah
Glen Canyon National Recreation Area
Lake Powell
Buttes of Utah
One-thousanders of the United States
Sandstone formations of the United States | Gunsight Butte | [
"Engineering"
] | 266 | [
"Colorado River Storage Project",
"Lake Powell"
] |
65,836,875 | https://en.wikipedia.org/wiki/Nussinov%20algorithm | The Nussinov algorithm is a nucleic acid structure prediction algorithm used in computational biology to predict the folding of an RNA molecule that makes use of dynamic programming principles. The algorithm was developed by Ruth Nussinov in the late 1970s.
Background
RNA origami occurs when an RNA molecule "folds" and binds to itself. This folding often determines the function of the RNA molecule. RNA folds at different levels, this algorithm predicts the secondary structure of the RNA.
Algorithm
Scoring
We score a solution by counting the total number of paired bases. Thus, attempting to maximize the score that maximizes the total number of bonds between bases.
Motivation
Consider an RNA sequence whose elements are taken from the set . Let us imagine we have an optimal solution to the subproblem of folding to , and an optimal solution for folding to . Now, to align to , we have two options:
Leave unpaired, and keep the structure of to . The score for this alignment will be equal to the score of the alignment of to , as no new base pairs were created.
Pair with , where . The score for this alignment will be the score of the base pairing, plus the score of the best alignment of to and to .
Algorithm
Consider an RNA sequence of length such that .
Construct an matrix . Initialize such that
for .
will contain the maximum score for the subsequence . Now, fill in entries of up and to the right, so that
where
After this step, we have a matrix where represents the optimal score of the folding of .
To determine the structure of the folded RNA by traceback, we first create an empty list of pairs . We initialize with . Then, we follow one of three scenarios.
If , the procedure stops.
If , then set and continue.
Otherwise, for all , if and are complementary and , append to , then traceback both with and .
When the traceback finishes, contains all of the paired bases.
Limitations
The Nussinov algorithm does not account for the three-dimensional shape of RNA, nor predict RNA pseudoknots. Furthermore, in its basic form, it does not account for a minimum stem loop size. However, it is still useful as a fast algorithm for basic prediction of secondary structure.
References
Bioinformatics algorithms | Nussinov algorithm | [
"Biology"
] | 461 | [
"Bioinformatics",
"Bioinformatics algorithms"
] |
65,838,044 | https://en.wikipedia.org/wiki/ML-SA1 | ML-SA1 is a chemical compound which acts as an "agonist" (i.e. channel opener) of the TRPML family of calcium channels. It has mainly been studied for its role in activating TRPML1 channels, although it also shows activity at the less studied TRPML2 and TRPML3 subtypes. TRPML1 is important for the function of lysosomes, and ML-SA1 has been used to study several disorders resulting from impaired lysosome function, including mucolipidosis type IV and Niemann-Pick's disease type C, as well as other conditions such as stroke and Alzheimer's disease.
References
Phthalimides
Amides | ML-SA1 | [
"Chemistry"
] | 151 | [
"Amides",
"Functional groups"
] |
65,838,697 | https://en.wikipedia.org/wiki/Light%20resin%20transfer%20moulding | Light resin transfer moulding (Light RTM) is a process by which products of Composite materials are manufactured using a closed mold system.
Procedure
Similar to the methods performed in resin transfer molding, Light RTM involves a closed mold process. A vacuum holds mold A and mold B together to result in two finished sides with fixed thickness levels. Vacuum rings around the tools hold the molds together for this process after dry fiber reinforcements are loaded into mold A before joining with mold B.
The air is vacuumed out of the molds with a lower vacuum level, separate from the tooling. After the air is removed the resin is injected into the part. The vacuum remains in effect into the resin is cured.
References
Composite materials
Composite material fabrication techniques | Light resin transfer moulding | [
"Physics"
] | 152 | [
"Materials",
"Composite materials",
"Matter"
] |
65,841,325 | https://en.wikipedia.org/wiki/EURO%20Advanced%20Tutorials%20in%20Operational%20Research | The EURO Advanced Tutorials in Operational Research are a series of short books devoted to advanced topics in Operational Research that are not available in textbooks. The scope of a Tutorial is to provide more detail about advanced topics in a relevant field to researchers and practitioners. The Book Series was established in 2014 and is published by Springer Science+Business Media. It is an official publication of the Association of European Operational Research Societies.
Renata Mansini, Włodzimierz Ogryczak, M. Grazia Speranza - Linear and Mixed Integer Programming for Portfolio Optimization
Alves, C., Clautiaux, F., de Carvalho, J.V., Rietz, J. - Dual-Feasible Functions for Integer Programming and Combinatorial Optimization
Henggeler Antunes, Carlos, João Alves, Maria, Clímaco, João - Multiobjective Linear and Integer Programming
Lancia, Giuseppe, Serafini, Paolo - Compact Extended Linear Programming Models
Duarte, Abraham, Laguna, Manuel, Marti, Rafael - Metaheuristics for Business Analytics
Zhao, Lima, Huchzermeier, Arnd - Supply Chain Finance
van Wageningen-Kessels, Femke - Traffic Flow Modelling
Doumpos, M., Lemonakis, C., Niklis, D., Zopounidis, C. - Analytical Techniques in the Assessment of Credit Risk
Bigi, G., Castellani, M., Pappalardo, M., Passacantando, M. - Nonlinear Programming Techniques for Equilibria
Vansteenwegen, Pieter, Gunawan, Aldy - Orienteering Problems: Models and Algorithms for Vehicle Routing Problems with Profits
Fajardo, M.D., Goberna, M.A., Rodríguez, M.M.L., Vicente-Pérez, J. - Even Convexity and Optimization
Menoncin, Francesco - Risk Management for Pension Funds
Brandimarte, Paolo - From Shortest Paths to Reinforcement Learning
Maniezzo, Vittorio, Boschetti, Marco Antonio, Stützle, Thomas - Matheuristics
Anjos, Miguel F., Vieira, Manuel V.C. - Facility layout. Mathematical optimization techniques and engineering (Review )
Celso C. Ribeiro, Sebastian Urrutia, Dominique de Werra - Combinatorial Models for Scheduling Sports Tournaments
The editors are
M. Grazia Speranza
Kenneth Sörensen
The past editors are
José Fernando Oliveira (2014-2023)
References
External links
Operations research | EURO Advanced Tutorials in Operational Research | [
"Mathematics"
] | 525 | [
"Applied mathematics",
"Operations research"
] |
65,842,021 | https://en.wikipedia.org/wiki/Royal%20Vale%20Heath | Royal Vale Heath (5 January 1883 – 25 July 1960) was a wealthy New York stockbroker and writer who became widely known as a magician and puzzle enthusiast. His magic tricks were often based on mathematics and he introduced the term "mathemagic" to describe them in a 1933 book titled Mathemagic. He was a frequent contributor to Scripta Mathematica, Hugard's Magic Monthly, and The Jinx.
He specialized in tricks involving dice, serial numbers and magic squares. He once constructed a magic square that remained a magic square even when it was turned upside-down.
In 1988 his work was exhibited at the David Winton Bell Gallery at Brown University.
Heath played a crucial role in the career of popular mathematics writer Martin Gardner. At a magic show in 1956 he introduced Gardner to flexagons and these folded paper shapes became the subject of Gardner's December 1956 column in Scientific American which launched his quarter century tenure there. Several of Heath's tricks have been collected in Gardner book Mathematics, Magic and Mystery.
References
Recreational mathematicians
American magicians
Writers from New York City
Mathematics popularizers
1883 births
1960 deaths | Royal Vale Heath | [
"Mathematics"
] | 230 | [
"Recreational mathematics",
"Recreational mathematicians"
] |
65,842,026 | https://en.wikipedia.org/wiki/Cruel%20jokes | Cruel jokes is a joke cycle dealing with cruelty and macabre topics. They belong to the category of sick humor. Typical examples:
– Mommy, why is daddy still sleeping?
– Shut up and keep digging.
– Mommy, why is daddy swimming so fast?
– Shut up and reload.
History
In American culture, jokes of this kind were recorded as early as in the 1930s as the Little Audrey jokes, with a larger cycle reported during the 1950s, many with the "Shut up..." punch line. Sutton-Smith remarks that the macabre nature of these jokes may also be compared with even earlier 19th-century Little Willie rhymes: "Little Willie with his thirst for gore / Nailed his mommy's baby to the door". The origin of Little Willie poetry and other sick humour is attributed to the 1899 book Ruthless Rhymes for Heartless Homes by minor poet Harry Graham.
A significant part of them was focused on in-family antagonism, stressing lovelessness and violence. Joseph Boskin attributes them to increased anxiety within families due to severe societal changes: two working parents, frequent relocations, increase in marital separation and divorce.
In 1960, Brian Sutton-Smith classified 155 collected "cruel" jokes into categories of murder of friend or relative, mutilation, cannibalism, corpses, beasts, excrement, degenerate parents, indifference to young, afflictions/disease/mutilation, religion, and famous people. He noted that at this time there was no established name for these jokes and they were variously called Cruel Jokes, Bloody Marys, Hate Jokes, Ivy League Jokes, Sadist Jokes, Gruesomes, Grimsels, Sick Jokes, Freddie Jokes, Depression Jokes, Meanie Jokes, and Comedy of Horror. The collected jokes appear to have originated during the 1950s and come both from American and British sources.
Sutton-Smith notices the major novelty: all mishaps with Little Audrey (being cooked, crushed, broken, etc.) were due to accidents, while in cruel jokes the macabre acts are intentional.
Roger Abrahams pointed out the terse "vignette" form of the joke, akin to a caption to a cartoon, and noticed that some of them have already been known in a more narrative form. "Son, will you quit kicking your sister" – "Oh, that's all right. She's already dead". Compare with: "The boy was walking down the street kicking a baby. A policeman walked up to him and said. 'What are you doing here?' – 'I am kicking the baby down the street'. – 'You are what?' – 'Oh, that's all right, he's dead.'"
Abrahams noted that this kind of anti-taboo jokes is a society-level check against the excessive repressiveness of societal norms.
See also
Dead baby jokes
Black comedy
Footnotes
References
Encyclopedia of Humor Studies, ed. Salvatore Attardo, 2014,
External links
Ruthless Rhymes for Heartless Homes By Col. D. Streamer (Harry Graham) Project Gutenberg
Joke cycles
Cruelty
Off-color humor | Cruel jokes | [
"Biology"
] | 645 | [
"Behavior",
"Aggression",
"Cruelty"
] |
42,973,489 | https://en.wikipedia.org/wiki/Path%20ordering%20%28term%20rewriting%29 | In theoretical computer science, in particular in term rewriting, a path ordering is a well-founded strict total order (>) on the set of all terms such that
f(...) > g(s1,...,sn) if f .> g and f(...) > si for i=1,...,n,
where (.>) is a user-given total precedence order on the set of all function symbols.
Intuitively, a term f(...) is bigger than any term g(...) built from terms si smaller than f(...) using a
lower-precedence root symbol g.
In particular, by structural induction, a term f(...) is bigger than any term containing only symbols smaller than f.
A path ordering is often used as reduction ordering in term rewriting, in particular in the Knuth–Bendix completion algorithm.
As an example, a term rewriting system for "multiplying out" mathematical expressions could contain a rule x*(y+z) → (x*y) + (x*z). In order to prove termination, a reduction ordering (>) must be found with respect to which the term x*(y+z) is greater than the term (x*y)+(x*z). This is not trivial, since the former term contains both fewer function symbols and fewer variables than the latter. However, setting the precedence (*) .> (+), a path ordering can be used, since both x*(y+z) > x*y and x*(y+z) > x*z is easy to achieve.
There may also be systems for certain general recursive functions, for example a system for the Ackermann function may contain the rule A(a+, b+) → A(a, A(a+, b)), where b+ denotes the successor of b.
Given two terms s and t, with a root symbol f and g, respectively, to decide their relation their root symbols are compared first.
If f <. g, then s can dominate t only if one of s'''s subterms does.
If f .> g, then s dominates t if s dominates each of ts subterms.
If f = g, then the immediate subterms of s and t need to be compared recursively. Depending on the particular method, different variations of path orderings exist. Here: chapter 4, p.55-64
The latter variations include:
the multiset path ordering (mpo), originally called recursive path ordering (rpo)
the lexicographic path ordering (lpo)
a combination of mpo and lpo, called recursive path ordering by Dershowitz, Jouannaud (1990)
Dershowitz, Okada (1988) list more variants, and relate them to Ackermann's system of ordinal notations. In particular, an upper bound given on the order types of recursive path orderings with n function symbols is φ(n,0), using Veblen's function for large countable ordinals.
Formal definitions
The multiset path ordering (>) can be defined as follows:
where
(≥) denotes the reflexive closure of the mpo (>),
{ s1,...,sm } denotes the multiset of s’s subterms, similar for t, and
(>>) denotes the multiset extension of (>), defined by { s1,...,sm } >> { t1,...,tn } if { t1,...,tn } can be obtained from { s1,...,sm }
by deleting at least one element, or
by replacing an element by a multiset of strictly smaller (w.r.t. the mpo) elements.
More generally, an order functional is a function O mapping an ordering to another one, and satisfying the following properties:
If (>) is transitive, then so is O(>).
If (>) is irreflexive, then so is O(>).
If s > t, then f(...,s,...) O(>) f(...,t,...).
O is continuous on relations, i.e. if R0, R1, R2, R3, ... is an infinite sequence of relations, then O(∪ Ri) = ∪ O(Ri).
The multiset extension, mapping (>) above to (>>) above is one example of an order functional: (>>)=O(>).
Another order functional is the lexicographic extension, leading to the lexicographic path ordering'''.
References
Rewriting systems
Order theory | Path ordering (term rewriting) | [
"Mathematics"
] | 1,029 | [
"Order theory"
] |
42,973,668 | https://en.wikipedia.org/wiki/Higher%20School%20of%20Mining%20Engineering | The Higher School of Mining Engineering (HSME) is a school located on the campus of the University of Vigo in Galicia, Spain. It offers undergraduate education as well as postgraduate courses for master's and doctoral degrees in mining engineering.
History
The study of mining engineering in Spain dates back to 1778, and focuses on locating and extracting natural and energy resources. This field of study is symbolized in the school logo by a hammer, a mallet, a palm, and laurel leaves. The depiction represents natural resource exploitation, environmental engineering, material craft, energy extraction, and civil works. HSME opened at the University of Vigo in 1992. At the time of founding, it was one of only four schools dedicated to mining engineering in Spain, and continues to be the only one of its kind in Galicia. Specializations include energy, materials, environmental studies, and mining.
After the academic year 2010/11, the school updated its study plan in accordance with the Bologna Process (RD 1393/2007 (modificado por RD 861/2010) for both undergraduate and postgraduate studies.
Studies
Undergraduate
Degree in Mining and Energetic Resources Engineering
Degree in Energy Engineering
Postgraduate
Master in Mining Engineering
Facilities
The current mining engineering building was recently renovated (inaugurated in 2005), in order to share central services such as the library, administration offices, and dining areas. The building is in the industrial style, with an area of approximately .
International
The school has several international agreements, especially through Europe's Erasmus Programme. It also holds bilateral agreements with a number of universities, primarily in South America:
Flensburg University of Applied Sciences (Germany)
École nationale supérieure des mines de Nancy (France)
National Technical University of Athens (Greece)
Polytechnic University of Milan (Italy)
Norwegian University of Science and Technology (Norway)
Technical University of Lisbon (Portugal)
Silesian University of Technology (Poland)
VSB – Technical University of Ostrava (Czech Republic)
Dokuz Eylül University (Turkey)
Federal University of Paraná (Brazil)
Pontifical Catholic University of Peru (Peru)
Science week exhibition
The school runs an annual science week for high school students, which provides an opportunity for younger students to observe the various scientific research activities of the school. This involves exposing them to fields such as energy, new materials, and environmental sciences. Student learning within the exhibition is divided into units, with a strong focus on interactive learning and hands-on activities. These methods are used to spark the interest of younger students, and encourage them to undertake scientific or technical education.
References
External links
University of Vigo
Students delegation
Universities in Galicia (Spain)
Educational institutions established in 1992
Schools of mines
University of Vigo
1992 establishments in Spain | Higher School of Mining Engineering | [
"Engineering"
] | 543 | [
"Schools of mines",
"Engineering universities and colleges"
] |
42,974,185 | https://en.wikipedia.org/wiki/Fomitiporia%20mediterranea | Fomitiporia mediterranea is a fungus species in the genus Fomitiporia associated with esca of grapevine.
References
External links
Hymenochaetaceae
Fungi described in 2002
Grapevine trunk diseases
Fungus species | Fomitiporia mediterranea | [
"Biology"
] | 48 | [
"Fungi",
"Fungus species"
] |
42,975,906 | https://en.wikipedia.org/wiki/Diplodia%20seriata | Diplodia seriata is an anamorphic fungus species in the genus Diplodia. It is a cause of bot canker of grapevine in Mexico.
References
External links
Index Fungorum
Botryosphaeriaceae
Fungi described in 1842
Fungal plant pathogens and diseases
Grapevine trunk diseases
Fungus species | Diplodia seriata | [
"Biology"
] | 64 | [
"Fungi",
"Fungus species"
] |
42,976,056 | https://en.wikipedia.org/wiki/Botryosphaeria%20viticola | Botryosphaeria viticola is a fungus species in the genus Botryosphaeria responsible for a grapevine trunk disease. This species has a Dothiorella anamorph. It has been isolated from pruned canes of Vitis vinifera cv. Garnatxa Negra in Catalonia, Spain.
References
External links
Index Fungorum
viticola
Fungi described in 2006
Grapevine trunk diseases
Fungus species | Botryosphaeria viticola | [
"Biology"
] | 92 | [
"Fungi",
"Fungus species"
] |
42,976,070 | https://en.wikipedia.org/wiki/Ichthyosaurus%20posthumus | "Ichthyosaurus" posthumus is a species of ichthyosaurs known from the Late Jurassic (early Tithonian age) Solnhofen Formation of Bavaria, Germany. Though several specimens have been referred to this species in the past, its type specimen consists only of isolated teeth that were destroyed during World War II, and it is today considered a nomen dubium. The teeth almost certainly do not belong to Ichthyosaurus itself, which was a wastebin taxon at the time this species was named.
References
Fossil taxa described in 1852
Ichthyosaurs of Europe
Late Jurassic ichthyosaurs
Solnhofen fauna
Nomina dubia | Ichthyosaurus posthumus | [
"Biology"
] | 135 | [
"Biological hypotheses",
"Nomina dubia",
"Controversial taxa"
] |
42,976,227 | https://en.wikipedia.org/wiki/Neofusicoccum%20australe | Neofusicoccum australe is a fungus species in the genus Neofusicoccum. It is responsible for a grapevine trunk disease.
A 2009 survey of endophytic fungi on woody species at two tuart woodlands of Southwest Australia (ecoregion), sampling acacia Acacia cochlearis, A. rostellifera, the sheoak Allocasuarina fraseriana, peppermint Agonis flexuosa, Banksia grandis, Eucalyptus marginata, sandalwood Santalum acuminatum and nominate species Corymbia calophylla (tuart), found around three quarters of isolates were taxa of the family Botryosphaeriaceae, eighty percent of which was this species.
References
External links
Botryosphaeriaceae
Fungi described in 2004
Grapevine trunk diseases
Fungus species | Neofusicoccum australe | [
"Biology"
] | 172 | [
"Fungi",
"Fungus species"
] |
42,977,434 | https://en.wikipedia.org/wiki/Xenobolus%20carnifex | Xenobolus carnifex is a species of spirobolidan millipede found in South India and Sri Lanka. It is a common species and can become a household pest, infesting and damaging thatched roofs, creating a "continual shower of faecal pellets", and invading food and water supplies. X. carnifex ranges from in length, with 48 to 50 body segments. The body color is dark or black, with a band of red or pink running down the dorsal midline.
References
Spirobolida
Millipedes of Asia
Arthropods of India
Arthropods of Sri Lanka
Pest arthropods
Taxa named by Johan Christian Fabricius
Animals described in 1775 | Xenobolus carnifex | [
"Biology"
] | 150 | [
"Pest arthropods",
"Pests (organism)"
] |
42,977,658 | https://en.wikipedia.org/wiki/Leonard%20W.%20Seymour | Leonard W. Seymour is a Professor of Gene Therapy at the University of Oxford's oncology department. As a cancer-oriented translational researcher, he investigates technologies utilised to enhance targeted therapy's (e.g. drugs, genes, oncolytic virus) delivery and develops related biological therapeutics under the support of Cancer Research UK.
Life
Professor Seymour was born in Plymouth, United Kingdom, in 1958. He read Biochemistry at the University of Manchester. He later formed a research group focused on gene delivery at the Cancer Research UK Institute in Birmingham, and then relocated to the University of Oxford in 2003 as Gene Therapy lead for the National Translational Cancer Research Network (NTRAC). There, he took part in forming the British Society for Gene Therapy (BSCGT) as a means to build the translational gene and cell therapy community within the UK.
Seymour served as the first President of the BSGCT from 2003 to 2009, currently serves as the General Secretary of the European Society for Gene and Cell Therapy, is indexed in Who's Who, and has produced approximately 140 primary scientific publications.
With Dr. Kerry Fisher, Prof. Seymour formed a biotech spinout company 'Hybrid Systems' which later became ‘PsiOxus Therapeutics Ltd’, with Cancer Research UK and the University of Birmingham. PsiOxus is now developing a cancer-killing 'oncolytic' group B adenovirus 'ColoAd1' in a series of clinical trials to treat cancer. More recently with Dr. Ryan Cawood, Dr. Seymour formed the plasmid expression company OxGENE, aiming to enable major improvements in the efficiency of genetic engineering and synthetic biology. In 2021, OxGENE was sold to WuXi AppTec.
His brother Paul Seymour is a professor of mathematics at Princeton University.
References
Academics of the University of Oxford
1958 births
Living people
Scientists from Plymouth, Devon
English geneticists
Synthetic biologists | Leonard W. Seymour | [
"Biology"
] | 390 | [
"Synthetic biology",
"Synthetic biologists"
] |
42,978,048 | https://en.wikipedia.org/wiki/HD%20240237 | HD 240237 is a star in the northern constellation of Cassiopeia. It is an orange star that can be viewed with binoculars or a small telescope, but is too faint to be seen with the naked eye at an apparent visual magnitude of 8.19. This object is located at a distance of approximately 3,100 light years away from the Sun based on parallax, but is drifting closer with a radial velocity of −25 km/s.
This is an aging giant star with a stellar classification of K2III; a star that has exhausted the supply of hydrogen at its core and expanded to 78 times the radius of the Sun. S. Gettel and associates (2011) estimate the star is around 270 million years old with 1.7 times the mass of the Sun. However, S. G. Sousa and associates found a much lower mass of 0.61 times the mass of the Sun. It is radiating 1,244 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,878 K.
Planetary system
In 2011, Gettel et al. announced the discovery of a planet orbiting this star. They estimated a mass around 5 times that of Jupiter, with an orbital period of and a moderate eccentricity. Sousa et al. (2015) gave a much lower estimate of . The designation b for this object, derives from the order of discovery. The designation of b is given to the first planet orbiting a given star, followed by the other lowercase letters of the alphabet. In the case of HD 240237, there was only one planet, so only the letter b is used.
References
K-type giants
Planetary systems with one confirmed planet
Cassiopeia (constellation)
Durchmusterung objects
240237
114840
J23154222+5802358 | HD 240237 | [
"Astronomy"
] | 376 | [
"Cassiopeia (constellation)",
"Constellations"
] |
42,978,555 | https://en.wikipedia.org/wiki/Al-Ca%20composite | Al-Ca composite is a high-conductivity, high-strength, lightweight composite consisting of sub-micron-diameter pure calcium metal filaments embedded inside a pure aluminium metal matrix. The material is still in the development phase, but it has potential use as an overhead high-voltage power transmission conductor. It could also be used wherever an exceptionally light, high-strength conductor is needed. Its physical properties make it especially well-suited for DC transmission. Compared with conventional conductors such as aluminium-conductor steel-reinforced cable (ACSR), all aluminium alloy conductors (AAAC), aluminium conductor alloy reinforced (ACAR), aluminium conductor composite reinforced ACCR and ACCC conductor that conduct alternating current well and DC current somewhat less well (due to the skin effect), Al-Ca conductor is essentially a single uniform material with high DC conductivity, allowing the core strands and the outer strands of a conductor cable to all be the same wire type. This conductor is inherently strong so that there is no need for a strong (usually poorly conductive) core to support its own weight as is done in conventional conductors. This eliminates the "bird caging", spooling, and thermal fatigue problems caused by thermal expansion coefficient mismatch between the core and outer strands. The Al-Ca phase interfaces strengthen the composite substantially, but do not have a noticeable effect on restricting the mean free path of electrons, which gives the composite both high strength and high conductivity, a combination that is normally difficult to achieve with both pure metals and alloys. The high strength and light weight could reduce the number of towers needed per kilometer for long distance transmission lines. Since towers and their foundations often account for 50% of a powerline's construction cost, building fewer towers would save a substantial fraction of total construction costs. The high strength also could increase transmission reliability in wind/ice loading situations. The high conductivity has the potential to reduce Ohmic losses.
Al-Ca composite conductor was invented by Russell and Anderson at Ames Laboratory of the U.S. Department of Energy with the goal of developing the next generation power transmission cables. Al/Ca composite is produced by powder metallurgy and severe deformation processing (extrusion, swaging, wire drawing). This process would be roughly two to three times more expensive than conventional melt processing for ACSR. But the cost saving on tower construction is projected to be substantially larger than the extra cost of the conducting cables. During deformation processing, the Ca powder particles deform into filaments surrounded by the Al matrix, which avoids exposing calcium, a reactive element, to air and moisture. The corrosion resistance of this composite has been found to be similar to that of pure aluminium.
Al-Ca composite has good microstructural stability even above 300 °C. The formation of intermetallic compounds at the interface would stabilize the microstructure to avoid the degradation of its various properties during exposure to elevated temperatures, such as those encountered during emergency overload situations.
Newest development
An Al/Ca (20 vol%) nanofilamentary metal-metal composite was produced by powder metallurgy and severe plastic deformation. Fine Ca metal powders (~200 μm) were produced by centrifugal atomization, mixed with pure Al powder, and deformed by warm extrusion, swaging, and wire drawing to a true strain of 12.9. The Ca powder particles became fine Ca nanofilaments that reinforce the composite substantially by interface strengthening. The conductivity of the composite is slightly lower than the rule-of-mixtures prediction due to minor quantities of impurity inclusions. The elevated temperature performance of this composite was also evaluated by differential scanning calorimetry and resistivity measurements.
The ultimate tensile strength is as high as 480 MPa, twice as that of ACSR.
The electrical conductivity 33.02 (μΩ m)−1 is higher than most current commonly used conductors.
References
Aluminium alloys
Calcium | Al-Ca composite | [
"Chemistry"
] | 812 | [
"Alloys",
"Aluminium alloys"
] |
42,978,594 | https://en.wikipedia.org/wiki/Child%20integration | Child integration is the inclusion of children in a variety of mature daily activities of families and communities. This contrasts with, for example, age segregation; separating children into age-defined activities and institutions (e.g., some models of organized schooling). Integrating children in the range of mature family and community activities gives equal value and responsibility to children as contributors and collaborators, and can be a way to help them learn. Children's integration provides a learning environment because children are able to observe and pitch in as they feel they can.
In the United States, child integration into "adult" life is not as common as it used to be. However, in other cultures social norms continue to incorporate children into the mature, productive activities of the family and community. In all cultures child integration is present in one way or another. For example, nearly all children's first language learning seems to be supported through integration with a mature linguistic community. Children usually are not taught in a classroom how to speak, but instead learn by observing the language and pitching it when they can.
Examples of children in collaborative communities
Children in Indigenous communities participate in mature activities with the guidance from someone who has practice in that activity. When engaged in shared endeavors the guider and the learner both notice and assess how much understanding the learner has in the task and the guider provides support if it is needed.
Indigenous cultures emphasize and instill values of being respectful, empathic and cooperative to their children. These values are practiced through tasks like co-sleeping and group play which helps bring about close connections within the family and community.
There are many different ways children can be integrated into society. One example, child care educators in certain Native communities, like the First Nations in Canada have taught children traditional language, where then the children have the responsibility to spread that language knowledge by teaching their parents and other family members, thus ingratiating them into society with responsibility to carry on the language legacy.
The Chippewa people have several different methods of teaching, such as lecturing and counseling, and integrating children into adult and community life. Overall, the children do the same tasks as their mothers and fathers just on a smaller scale. For example, a young girl might learn to make nets like her mother and uses the same knots her mother uses but makes smaller nets than her mother. Throughout the years she will slowly make bigger and bigger nets and perfect the skill that her mother and her mother's mother before her had. These skills may be learned by observation and sometimes if a specific person in the community is very skillful at something, the adults might recommend the child go find that person and learn from them.
Community endeavors
The integration of children into community and family endeavors in Indigenous American Communities begins as early as infancy. Among the Mayan peoples of the Yucatan peninsula, children are allowed to roam freely allowing them ample opportunity to become acquainted with the mundane activities of the family. In the Mexican indigenous community of the Mazahua, children will coordinate their activities with those of their parents in a manner that allows them to cooperate in familial endeavors and may at times be granted a leading position in the endeavor. Children are considered to be valuable and responsible contributors of the community. The process of child integration into mature activities begins in infancy and continuous throughout time; between ages 3 and 4 the child will already be participating in some of the family's day to day activities, by ages 5 and 7 that child will already be cooperating in most of the endeavors that adults engage in and will have also earned several important responsibilities which can range from performing certain household tasks to providing childcare for younger siblings.
The cultural practice of integrating children in the mature activities of the family and community is common in many Indigenous American communities. Many integrate children into "adult" activities, work life, and other cultural practices at a very young age. Among the Quechua people of the Andes, families accept the child as a part of an integral process towards a collective wellbeing. Two-year-olds in the Chillihuani community frequently get their own food and drink, and those of herding families participate in herding and caring for the animals. In this community, work and play are not two separable things (i.e., one for adult and one for children). The children enjoy having real responsibilities and find pride in being able to contribute to their society.
Similarly, some Chippewa communities of Washington also commonly integrate children in the mature activities of the community. Children are expected to observe and work with their parent to be able to develop skills for that line of work. Young girls assist their mothers with beadwork, household chores, chopping wood, etc., and boys are expected to work on canoe-making with the men and are given arrows to learn hunting skills at 5 or 6 years old.
Daily household activities provide the child the ability to learn cultural practices such as different food dishes, hygiene, and parenting skills, as well as the social values and religious beliefs. It is common for children in Indigenous American communities to learn through trial and error instead of explicit instruction. This is due to the cultural understanding of "echando a perder se enesena la gente" (throwing to lose, teaches people) which promotes optimism and growth of the child in the community, allowing the youth to feel comfortable making mistakes as long as they keep working towards their goal.
Children in the town of Tepoztlan are encouraged to participate in community activities. The people there believe that everyone can contribute something to community endeavors. Young children are encouraged to participate by being brought to various meetings and activities by their mothers, so as they grow older, they request to be admitted into the group on their own will.
Political movements and civic life
Some Indigenous American communities can incorporate young children into the political activities of the community. Political violence and displacement within the community of San Agustin Loxicha, Oaxaca created an important aspect of child participation in the community's struggle. In this community, it is common for young children to take part in marches or sit-ins, hunger strikes, school life, child play, and accept the political part of their lives instead of seeing it as a hardship or something to be pitied.
In the Nahua indigenous town of Tepoztlan located near Mexico City, children, adolescents, and older members of the community were involved in a 5-year long political movement against the construction of a golf course in their town. During assemblies children participated by aiding in the preparation of food and drinks for the crowd, while adolescents brought in groups of peers to further political involvement in the community. During marches and protest children and adolescents were active members of the civic movement. Any repression that the group suffered on behalf of the authorities was not seen as something negative in the experience of the youth, but was instead something that would further motivate their desire to be politically active. Through their integration into the political structure of the civil movement, the child's/adolescent's understanding of the issue expanded to such a degree that they would not only have physical presence in the group but would also be capable of offering new perspectives and potential solutions to the issue at hand. It is important to note that none of the children and adolescents involved were forced to do so. If a child showed an interest in the political movement they were encouraged by the adults to become participants but ultimately the choice was always left to them. Once a child decided to become involved the parents and other adults respected the pace and rhythm of that involvement.
Language brokering
In some immigrant communities, children link their family and friends to the environment around them by translating and paraphrasing words, phrases or occurring situations. This practice is known as language brokering and is used by children in immigrant communities to integrate themselves into family endeavors and into civil society. The child's contribution by language brokering integrates them into many environments, such as the doctor's office, at parent-teachers' conferences, banks, housing offices, and various sorts of negotiation activities. Subsequently, children who engage in language brokering are more likely to also be representatives of their community when transitioning into adulthood. Child integration has become very important to form linkages between new immigrant communities and the predominant culture and new forms of bureaucratic systems.
With the increased interaction in larger societies children in Indigenous Mayan communities who are bilingual help monolingual parents as interpreters. For example, the children will translate for parents when selling products in the barrios of Cancun, where the primary language is Spanish.
Productive endeavors
In some indigenous communities, children are often integrated as active participants into family and community work. Child work is often a vital contribution towards community productivity and typically involves non-exploitative motivations for children's engagement in work activities.
In some families, young children contribute to the family's finances by taking a job in a factory or a store under the supervision of a formal adult figure, while some join the family business under the oversight of their parents and older siblings. When children join the family business they tend to gain knowledge of a trade such as accounting, public relations and how to be able to time manage. Some children not only obtain an economic boost for the family as a whole, but also learn autonomy and altruism with regards to having their own earned income to support the family and also to spend for themselves.
Children's motivation as integrated contributors
Children in Indigenous American communities pitch in to community endeavors because they experience their contribution having a tangible effect on their community. The children often contribute without being told and children get to learn how to do the activity as they contribute. However, children aren't just born with this way of learning by observation; they have been given the opportunity by being encouraged to attend, observing, and participating in mature activities.
In indigenous communities, children's and adult's interests in participation must be viewed as equal, not just the adults forcing their views onto the children. Children are seen as a part of community just as much as adults. In many cultures, children are expected to take on tasks that are important to community. Children are also seen as integral members of the community, rather than separate from adults. Some cultures even give children control over specific goods, such as livestock or arable land and the expectations that come with this may also be seen as forms of participation. These ideas of children actively participating in their communities and influencing the society opens up opportunities for the participation of children
History of age segregation in the West
Segregating children by age was not always the norm in the United States. A century and a half ago, children in the US had access to a wide range of adult activities and were integrated into multiple aspects of family functioning and survival. The change from this integration into segregation was a product of industrialization, Western formal schooling, child labor laws, social services agencies, and the rise of disciplines such as Psychology and Education. A combination of the above caused a shift from family working as a unit to separation of economic activities and services such as childcare emerged.
References
Indigenous education
Human development
Education in the United States | Child integration | [
"Biology"
] | 2,248 | [
"Behavioural sciences",
"Behavior",
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42,979,461 | https://en.wikipedia.org/wiki/Psammodesmus%20bryophorus | The moss millipede (Psammodesmus bryophorus) is a keeled millipede of the family Platyrhacidae native to Colombia. It was described in 2011, and with several species of symbiotic moss found growing on its dorsal surface, it is the first millipede known with epizoic plants. At least 10 species of bryophytes belonging to families Pilotrichaceae, Lejeuneaceae, Fissidentaceae, Metzgeriaceae and Leucomiaceae have been found to grow on the millipede's dorsum; these plants are believed to camouflage the millipede as its cuticle provides a stable substrate.
Description
Adult moss millipedes have 19 body segments, each with a pair of wide keels; the coloration of their dorsum ranges from dark brown to black, having two light-colored stripes on the prozonites and metatergites of segments 2-19. The edges of the paranota are white and the legs, antennae and ventral surface of the trunk are reddish brown.
Habitat
P. bryophorus is found in Río Ñambí Natural Reserve, a transitional Andean-Pacific forest in South West Colombia, preferring tree trunks and leaves, about 1m above the ground; however, they can also be found between the leaf litter and the soil surface.
References
Polydesmida
Endemic fauna of Colombia
Symbiosis
Millipedes of South America | Psammodesmus bryophorus | [
"Biology"
] | 300 | [
"Biological interactions",
"Behavior",
"Symbiosis"
] |
42,979,524 | https://en.wikipedia.org/wiki/Intertrial%20priming | In cognitive psychology, intertrial priming is an accumulation of the priming effect over multiple trials, where "priming" is the effect of the exposure to one stimulus on subsequently presented stimuli. Intertrial priming occurs when a target feature (the characteristic that distinguishes targets from non-targets) is repeated from one trial to the next, and typically results in speeded response times to the target. A target is the stimulus participants are required to search for. For example, intertrial priming occurs when the task is to respond to either a red or a green target, and the response time to a red target is faster if the preceding trial also has a red target.
Top-down and bottom-up attention
Visual attention is influenced by top down and bottom up attentional processes. Top-down attention is allocated based on an observer's current knowledge about the stimuli. Participants in an experiment might be instructed to search for, and respond to a target object presented in a display that is a different colour than the other objects presented simultaneously. Top down knowledge of the dimension of the target (i.e. colour) can speed response times to target identification.
Bottom-up attention is involuntarily and automatically directed towards salient features in the environment such as a bright colour among dull colours. In experimental settings, the more different a stimulus is from other stimuli in a visual display, the more salient it is. Bottom-up attention is typically not guided by observers' goals or knowledge, only by the physical properties of the stimuli. Many studies employ various methods involving intertrial priming to assess the contribution of top down versus bottom up processes in guiding attention in visual search tasks.
Integrative framework
There are factors in visual search tasks that the top down versus bottom up dichotomy does not take into consideration. Not all selection biases can be explained by physical saliency (bottom up) or observer goals (top down). Studies that have found that stimuli that are equally salient and are connected with rewards and can draw a participants' attention, even if this choice doesn't match their selection goals. An alternative framework has been proposed where past selection history, current goals and physical salience are integrated in a model of attentional control.
Measuring the effects of intertrial priming
Intertrial priming is an important aspect to consider in designing an experiment as it can influence the results if it is not considered/controlled. Intertrial priming is often measured using a visual search task. A typical visual search task involves participants searching for, and responding to, a target amongst a group of non-target items. Intertrial priming performance is generally measured by recording participants' reaction times to identify a target and comparing these times across trials. Different trial designs and visual search tasks can be employed to measure intertrial priming.
Blocked and mixed trials
Studies often compare blocked and mixed visual search trials to measure intertrial priming. Blocked trials are multiple, successively presented visual search trials that include the same target, and mixed trials are a randomised series of trials, each trial consisting of different targets. For example, a blocked trial condition may include searching for a green circle in trial 1, and in multiple successive preceding trials, whereas a mixed trial condition may include searching a for a green circle in trial 1, but a red circle in the proceeding trials. Blocking trials can control for effects of variability in targets. When a target with the same defining feature is repeated across trials (blocked conditions), participants reaction times are faster than when the target is not the same across trials (mixed conditions). This repetition effect is also cumulative. As the number of target repetitions increases, up to a certain point, participants reaction times are faster each time they are exposed to the same target in repeated trials. In mixed and blocked trials there can be a disparity in intertrial priming that results in faster reaction times in the blocked trials. Reaction times may be faster in blocked trials because participants are required to respond to targets that differ in only one dimension from non-targets.
Cueing
A cue is a presentation of a stimulus prior to a trial to inform the participant of an upcoming target feature. For example, a blue circle may be shown before a trial to signify a blue circle will be the target in the upcoming trial. Target relevant cues may be presented to participants to decrease their reaction time to the target in the display. These cues may be valid or invalid. Valid cues correctly predict the target stimulus but invalid cues do not. For example, if the target in an upcoming trial is a blue circle, a blue circle presented as a cue would be valid, but if a red circle was presented as a cue it would be invalid, as it does not correctly predict the blue circle target stimulus. Reaction times to valid cues are typically faster than reaction times to invalid cues. This phenomenon is known as a cueing effect.
Cue validity effect
When a valid cue has a low probability of correct target prediction, there can still be a reliable cueing effect for valid cues, and faster reaction times to valid cues than invalid cues. This suggests that the cueing effect is not affected by the predictive nature of the cue, and may not be due to top-down control. If top-down control is involved in the response selection then invalid trials should have a faster response than valid trials because participants are aware that the likelihood of being presented with a valid trial is very low.
Types of visual search
Pop-out search
Pop-out search tasks include a target that differs in one dimension from a group of homogeneous non-target items. A dimension is a categorical feature of a stimulus such as its colour (i.e. a red target among green non-targets), its shape (a square target among circle non-targets) or its orientation (a vertically presented target among horizontal non-targets). Response times in pop-out searches are generally faster to targets when the colour of both targets and distractors remains the same throughout trials, and slower when these colours are switched during trials.
Conjunctive search
A conjunctive search involves non-target stimuli that have more than one dimension in common with the target stimulus. For example, when a target is a green circle in a conjunctive search, non-targets (distractors) could be red circles and green squares. The target will share one dimension in common with one set of non-targets (i.e. shape) and another dimension in common with the other non-target group (i.e. colour). If target and distractor features are the same over consecutive trials, response times are faster than when these dimensions are not repeated.
Why it occurs (major theories)
Dimension-weighting account theory
The "dimension-weighting account" of visual selection states that there is a limit to the attentional weight that can be allocated to a particular dimension of an object at any one time. The dimensions of stimuli perceived as important to an observer are allocated more attentional weight (i.e. a target in a visual search), resulting in faster detection times. If a target dimension is known in advance, this can increase the saliency signals of the target. On the other hand, if the target dimension is unknown, attentional weight has to be shifted to the target dimension. When target dimensions remain the same across trials there is no change in attentional weight required, resulting in faster reaction times (intertrial facilitation).
Priming of pop-out hypothesis
The priming of pop-out hypothesis suggests performance in a visual search task involving a pop-out target can be affected by the search history of specific target features in previous trials. If target and distractor features are repeated in subsequent trials, reaction times will be faster than if these features change across trials. The hypothesis proposes the repetition of a target used in a preceding trial makes its pop-out features more salient to an observer and therefore increases the likelihood the observer will attend to it.
Episodic retrieval hypothesis
The episodic retrieval model suggests reduced response times in intertrial priming are due to the observers' retrieval of episodic memories relevant to the task. The hypothesis states that visual search is composed of three successive stages of processing:
search for a target,
decide if the chosen target is the target of interest, and
select and respond to the chosen target.
This hypothesis argues that when a target presented in a previous trial is presented again in the current trial, processing of the target is accelerated in the target decision stage of the model, so that after identification the target is verified to assess whether it matches the previous target stored in episodic memory.
Perceptual grouping of distractors account
Many theories focus on the repetition of target features as dominant explanation for the repetition effects seen in intertrial priming. If target features are the same over consecutive trials but distractor features are changed, response times are not as fast as if both target and distractor features are kept constant over trials. This suggests that intertrial priming may mainly be due to distractor feature repetition, and target feature repetition influences this only slightly. This distractor-based priming may be due to faster perceptual grouping of distractors across trials. Perceptual grouping of distractors allows the target presence or absence to be distinguished more quickly. However, the repetition of target defining features cannot be excluded as a contributor to the priming effect found in conjunctive searches.
See also
Priming
Thin-slicing
References
Cognitive psychology
Attention
Perception | Intertrial priming | [
"Biology"
] | 1,944 | [
"Behavioural sciences",
"Behavior",
"Cognitive psychology"
] |
42,979,913 | https://en.wikipedia.org/wiki/Hiragino | is a typeface family designed by sold by Screen Graphics Solutions Co., Ltd. (part of Screen Holdings, formally Dainippon Screen Mfg.) to professionals since 1993. It is one of the built-in fonts in macOS and iOS. This series includes not only Japanese Mincho (serif), Kaku Gothic (sans-serif), Maru Gothic (round sans-serif), semi-cursive script and kana typefaces, but also a sans-serif typeface for Simplified Chinese.
The typeface family is named after the area in Kita-ku, Kyoto, Japan.
Jiyukobo
Jiyukobo Ltd. is a corporation founded by type designers Tsutomu Suzuki, Osamu Torinoumi, and Keiichi Katada, who formerly worked for the phototypesetting corporation Shaken (), in Tokyo in 1989. Suzuki served as the president, but after his death in 1998, Torinoumi took his place.
References
External links
Screen's Hiragino website
Typefaces and fonts introduced in 1993
1993 establishments in Japan
CJK typefaces | Hiragino | [
"Technology"
] | 235 | [
"Computing stubs",
"Digital typography stubs"
] |
42,980,268 | https://en.wikipedia.org/wiki/Visual%20spatial%20attention | Visual spatial attention is a form of visual attention that involves directing attention to a location in space. Similar to its temporal counterpart visual temporal attention, these attention modules have been widely implemented in video analytics in computer vision to provide enhanced performance and human interpretable explanation of deep learning models.
Spatial attention allows humans to selectively process visual information through prioritization of an area within the visual field. A region of space within the visual field is selected for attention and the information within this region then receives further processing. Research shows that when spatial attention is evoked, an observer is typically faster and more accurate at detecting a target that appears in an expected location compared to an unexpected location. Attention is guided even more quickly to unexpected locations, when these locations are made salient by external visual inputs (such as a sudden flash). According to the V1 Saliency Hypothesis, the human primary visual cortex plays a critical role for such an exogenous attentional guidance.
Spatial attention is distinctive from other forms of visual attention such as object-based attention and feature-based attention. These other forms of visual attention select an entire object or a specific feature of an object regardless of its location, whereas spatial attention selects a specific region of space and the objects and features within that region are processed.
Measures of visual spatial attention
Spatial cueing experiments
A key property of visual attention is that attention can be selected based on spatial location and spatial cueing experiments have been used to assess this type of selection. In Posner's cueing paradigm, the task was to detect a target that could be presented in one of two locations and respond as quickly as possible. At the start of each trial, a cue is presented that either indicates the location of the target (valid cue) or indicates the incorrect location thus misdirecting the observer (invalid cue). In addition, on some trials there is no information given about the location of the target, as no cue is presented (neutral trials). Two distinct cues were used; the cue was either a peripheral 'flicker' around the target's location (peripheral cue) or the cue was centrally displayed as a symbol, such as an arrow pointing to the location of the target (central cue). Observers are faster and more accurate at detecting and recognising a target if the location of the target is known in advance. Furthermore, misinforming subjects about the location of the target leads to slower reaction times and poorer accuracy relative to performance when no information about the location of the target is given.
Spatial cueing tasks typically assess covert spatial attention, which refers to attention that can change spatially without any accompanying eye movements. To investigate covert attention, it is necessary to ensure that observer's eyes remain fixated at one location throughout the task. In spatial cueing tasks, subjects are instructed to fixate on a central fixation point. Typically it takes 200 ms to make a saccadic eye movement to a location. Therefore, the combined duration of the cue and target is typically presented in less than 200 ms. This ensures that covert spatial attention is being measured and the effects are not due to overt eye movements. Some studies specifically monitor eye movements to ensure that the observer's eyes are continually fixated on the central fixation point.
The central and peripheral cues in spatial cueing experiments can assess the orienting of covert spatial attention. These two cues appear to use different mechanisms for orienting spatial attention. The peripheral cues tend to attract attention automatically, recruiting bottom-up attentional control processes. Conversely, central cues are thought to be under voluntary control and therefore use top-down processes. Studies have shown that peripheral cues are difficult to ignore, as attention is oriented towards the peripheral cue even when the observer knows the cue does not predict the location of the target. Peripheral cues also cause an allocation of attention much faster than central cues, as central cues require greater processing time to interpret the cue.
Spatial probe experiments
In spatial cueing tasks, the spatial probe (cue) causes an allocation of attention to a particular location. Spatial probes have also been often used in other types of tasks to assess how spatial attention is allocated.
Spatial probes have been used to assess spatial attention in visual searches. Visual search tasks involve the detection of a target among a set of distractors. Attention to the location of items in the search can be used to guide visual searches. This was demonstrated by valid cues improving the identification of targets relative to the invalid and neutral conditions. A visual search display can also influence how fast an observer responds to a spatial probe. In a visual search task, a small dot appeared after a visual display and it was found that observers were faster at detecting the dot when it was located at the same location as the target. This demonstrated that spatial attention had been allocated to the target location.
The use of multiple tasks simultaneously in an experiment can also demonstrate the generality of spatial attention, as allocation of attention to one task can influence performance in other tasks. For example, it was found that when attention was allocated to detecting a flickering dot (spatial probe), this increased the likelihood of identifying nearby letters.
Distribution of spatial attention
The distribution of spatial attention has been subject to considerable research. Consequently, this has led to the development of different metaphors and models that represent the proposed spatial distribution of attention.
Spotlight metaphor
According to the 'spotlight' metaphor, the focus of attention is analogous to the beam of a spotlight. The moveable spotlight is directed at one location and everything within its beam is attended and processed preferentially, while information outside the beam is unattended. This suggests that the focus of visual attention is limited in spatial size and moves to process other areas in the visual field.
Zoom-lens metaphor
Research has suggested that the attentional focus is variable in size. Eriksen and St James proposed the 'zoom-lens' metaphor, which is an alternative to the spotlight metaphor and takes into account the variable nature of attention. This account likens the distribution of attention to a zoom-lens that can narrow or widen the focus of attention. This supports findings that show attention can be distributed both over a large area of the visual field and also function in a focused mode. In support of this analogy, research has shown that there is an inverse relationship between the size of the attentional focus and the efficiency of processing within the boundaries of a zoom-lens.
Gradient model
The Gradient Model is an alternative theory on the distribution of spatial attention. This model proposes that attentional resources are allocated in a gradient pattern, with concentrated resources in the centre of focus and resources decrease in a continuous fashion away from the centre. Downing conducted research using an adaptation of Posner's cueing paradigm that supported this model. The target could appear in 12 potential locations, marked by boxes. Results showed that attentional facilitation was strongest at the cued location and gradually decreased with distance away from the cued location. However, not all research has supported the gradient model. For example, Hughes and Zimba conducted a similar experiment, using a highly distributed visual array and did not use boxes to mark the potential locations of the target. There was no evidence of a gradient effect, as the faster responses were when the cue and target were in the same hemifield and slower responses when they were in different hemifields. The boxes played an important role in attention as a later experiment, used the boxes and consequently found a gradient pattern. Therefore, it is considered that the size of the gradient can adjust according to the circumstances. A broader gradient may be adopted when there is an empty display, as attention can spread and is only restricted by hemifield borders.
Splitting spatial attention
It is debated in research on visual spatial attention whether it is possible to split attention across different areas in the visual field. The 'spotlight' and 'zoom-lens' accounts postulate that attention uses a single unitary focus. Therefore, spatial attention can only be allocated to adjacent areas in the visual field and consequently cannot be split. This was supported by an experiment that altered the spatial cueing paradigm by using two cues, a primary and a secondary cue. It was found that the secondary cue was only effective in focusing attention when its location was adjacent to the primary cue. In addition, it has been demonstrated that observers are unable to ignore stimuli presented in areas situated between two cued locations. These findings have proposed that attention cannot be split across two non-contiguous regions. However, other studies have demonstrated that spatial attention can be split across two locations. For example, observers were able to attend simultaneously to two different targets located in opposite hemifields. Research has even suggested that humans are able to focus attention across two to four locations in the visual field. Another perspective is that spatial attention can be split only under certain conditions. This perspective suggests that the splitting of spatial attention is flexible. Research demonstrated that whether spatial attention is unitary or divided depends on the goals of the task. Therefore, if dividing attention is beneficial to the observer then a divided focus of attention will be utilised.
One of the main difficulties in establishing whether spatial attention can be divided is that a unitary focus model of attention can also explain a number of the findings. For example, when two non-contiguous locations are attended to, it may not be that attention has been split between these two locations but instead it may be that the unitary focus of attention has expanded. Alternatively, the two locations may not be attended to simultaneously and instead the area of focus is moving quickly from one location to another. Consequently, it appears very difficult to prove undoubtedly that spatial attention can be split.
Deficits in visual spatial attention
Hemineglect
Hemineglect , also known as unilateral visual neglect, attentional neglect, hemispatial neglect or spatial neglect, is a disorder incorporating a significant deficit in visuospatial attention. Hemineglect refers to the inability of patients with unilateral brain damage to detect objects in the side of space contralateral to the lesion (contralesional); i.e. damage to the right cerebral hemisphere resulting in neglect of objects on the left side of space, and is characterized by hemispheric asymmetry. Performance is generally preserved in the side ipsilateral to the lesion (ipsilesional). Hemineglect is more frequent and arguably more severe following damage to the right cerebral hemisphere of right-handed subjects. It has been proposed that the right parietal lobes are comparatively more responsible for the allocation of spatial attention, therefore damage to this hemisphere often produces more severe effects. Additionally, it is difficult to map with accuracy the visual sensory deficits in the neglected hemifield.
Neglect is diagnosed using a variety of paper-and-pencil tasks. A common method is the Complex Figure Test (CFT). The CFT requires patients to copy a complicated line drawing, and then reproduce it from memory. Often patients will neglect features present on the contralesional side of space and objects. Patients with neglect will perform similarly when reproducing mental images of familiar places and objects. A common error is the failure to include numbers on the left side of a picture when drawing an analogue clock from memory, for example, all of the numbers may be positioned on the right side of the clock face.
Another paper-and-pencil task is the line bisection task. In this exercise, patients are required to divide a horizontal line halfway along. Patients with neglect will often bisect the line to the right of the true centre, leaving the left portion of the line unattended to.
Object cancellation tasks are also used to determine the extent of potential deficit. During this task, patients are required to cancel out (cross out) all of the objects in a cluttered display (e.g. lines, geometric shapes, letters, etc.). Patients with damage primarily to the right parietal area fail in the detection of objects in the left visuospatial field, and these are often not crossed out by the patient. In addition, those patients who may be severely affected tend to fail in detecting their errors on visual inspection.
Extinction
Extinction is a phenomenon observable during double simultaneous stimulation of both left and right visual fields. Patients with extinction will fail to perceive the stimulus in the contralesional visual field when presented in conjunction with a stimulus in the ipsilesional field. However, when presented on its own, patients can correctly perceive the contralesional stimulus. Thus, patients with neglect fail to report stimuli present in the aberrant field, whereas patients with extinction fail to report stimuli in the aberrant field only when double simultaneous presentations occur in both hemifields. Analogous to neglect, extinction affects the contralesional visuospatial field in majority of patients with unilateral damage. Anatomical correlates of visuospatial neglect and extinction do not overlap absolutely, with extinction proposed to be associated with subcortical lesions.
A common method in quick detection of visuospatial extinction is a Finger Confrontation Model. Utilized as standard bedside evaluation, the task requires the patient to indicate (either verbally or by pointing) in which visual field the doctor's hand or finger is moving, while the doctor makes a wiggling motion with his index. This enables the doctor to distinguish between deficits resembling neglect and those which may indicate extinction, by presenting either a single stimulus in the contralesional field or two simultaneous stimuli in both the contralesional and ipsilesional visual fields. This quick test can be used immediately in a hospital setting for quick diagnosis, and can be particularly useful following strokes and seizures.
Regions associated with impairment of visuospatial attention
Parietal damage
The posterior parietal region is arguably the most extensively studied in relation to visuospatial attention. Patients with parietal lobe damage most often fail to attend to stimuli located on the contralesional hemisphere, as seen in patients with hemineglect/unilateral visual neglect. As such, they may fail to acknowledge a person sitting to their left, they may neglect to eat food positioned on their left, or make head or eye movements to the left. Computed tomography (CT) studies have demonstrated that the inferior parietal lobule in the right hemisphere is the most frequently damaged in patients with severe neglect.
Parietal damage may decrease the ability to reduce decision noise. Spatial cues appear to reduce the uncertainty of a visuospatial decision. Disruption to spatial orienting, as seen in hemineglect, suggests that patients with damage to the parietal region may experience an increased difficulty in decision-making regarding targets located in the contralesional field.
Damage to the parietal region may also increase illusory conjunctions of features. Illusory conjunctions occur when people report combinations of features which did not occur. For example, when presented with an orange square and a purple circle, the participant may report a purple square or an orange circle. Although it would typically require special circumstances for a non-impaired person to produce an illusory conjunction, it appears that some patients with damage to the parietal cortex may demonstrate a vulnerability to such visuospatial impairments. Results from parietal patients suggest that the parietal cortex, and therefore spatial attention, may be implicated in solving this problem of binding features.
Frontal lobe damage
Lesions to the frontal cortices have long been known to precede spatial neglect and other visuospatial deficits. Specifically, frontal lobe damage has been associated with a deficit in the control of over attention (the production of eye movements). Lesions to the superior frontal lobe areas that include the frontal eye fields seem to disrupt some forms of overt eye movements. It has been demonstrated by Guitton, Buchtel, & Douglas that eye movement directed away from an abruptly appearing visual target ("antisaccade") is remarkably impaired in patients with damage to the frontal eye fields, who frequently made reflexive eye movements to the target. When frontal eye field patients did make antisaccades, they had increased latency of their eye movements compared to controls. This suggests that the frontal lobes, specifically the dorsolateral region containing the frontal eye fields, play an inhibitory role in preventing reflexive eye movements in overt attention control. Further, the frontal eye fields or surrounding areas may be critically associated with neglect following dorsolateral frontal lesions.
Frontal lobe lesions also appear to produce deficits in visuospatial attention related to covert attention (the orienting of attention without the requirement eye movement). Using Posner's Spatial Cueing Task, Alivesatos and Milner (1989; see ) found that participants with frontal lobe damage demonstrated a comparably smaller attentional benefit from the valid cues than control participants or participants with temporal lobe damage. Voluntary orienting of frontal lobe patients appear to be impaired.
The right lateral frontal lobe region was also found to be associated with left-sided visual neglect in an investigation carried out by Husain & Kennard. A region of overlap was found in the location of lesions in four of five patients with left-sided visual neglect, specifically the dorsal aspect of the inferior frontal gyrus and the underlying white matter. Additionally, overlap of lesion areas was also detected in the dorsal region of Brodmann area 44 (anterior to the premotor cortex). These results further implicate the frontal lobe in directing attention in visual space.
Thalamic nuclei damage (pulvinar nucleus)
The thalamic nuclei have been speculated to be involved in directing attention to locations in visual space. Specifically, the pulvinar nucleus appears to be implicated in the subcortical control of spatial attention, and lesions in this area can cause neglect. Evidence suggests that the pulvinar nucleus of the thalamus might be responsible for engaging in spatial attention at a previously cued location. A study by Rafal and Posner found that patients who had acute pulvinar lesions were slower to detect a target which appeared in the contralesional visuospatial field compared to the appearance of a target in the ipsilesional field during a spatial cuing task. This suggests a deficit in the ability to use attention to improve performance in detection and processing of visual targets in the contralesional region.
Use in camouflage
Camouflage relies on deceiving the cognition of the observer, such as a predator. Some camouflage mechanisms such as distractive markings likely function by competing for visual attention with stimuli that would give away the presence of the camouflaged object (such as a prey animal). Such markings have to be conspicuous, and positioned away from the outline so as to avoid drawing attention to it, in contrast to disruptive markings which work best when in contact with the outline.
See also
Activity recognition / action recognition
Attention
Visual temporal attention
References
Attention
Visual perception
Spatial cognition | Visual spatial attention | [
"Physics"
] | 3,848 | [
"Spacetime",
"Space",
"Spatial cognition"
] |
42,980,901 | https://en.wikipedia.org/wiki/Callistosporium%20purpureomarginatum | Callistosporium purpureomarginatum is a species of agaric fungus in the family Callistosporiaceae. Found in the United States, it was officially described in 1996.
Taxonomy
C. purpureomarginatum was classified by the mycologists Raymond M. Fatto and Alan E. Bessette in 1996.
Description
Callistosporium purpureomarginatum is a small mushroom with a distinctive purplish red cap which discolours at it ages or dries.
Cap: 1-4cm. Starts convex before flattening with age. Stem: 1.5-4cm in height and 2-5mm in thickness. Gills: Purple brown, discolouring to yellow or olive whilst sometimes retaining purple fringes. Spore print: White. Spores: Smooth, ellipsoid. 4.7 x 2.5-4 μm. Taste: Indistinct or bitter. Smell: Indistinct.
References
External links
Fungi described in 1996
Fungi of the United States
Agaricales
Fungi without expected TNC conservation status
Fungus species | Callistosporium purpureomarginatum | [
"Biology"
] | 234 | [
"Fungi",
"Fungus species"
] |
42,981,259 | https://en.wikipedia.org/wiki/List%20of%20animals%20that%20produce%20silk | Silk is produced by a variety of animals, for different purposes, with various types being produced.
Insects
Silkworms produce silk when undergoing larval to adult metamorphosis.
Raspy crickets produce silk to form nests.
Honeybee and bumblebee larvae produce silk to strengthen the wax cells in which they pupate.
Bulldog ants spin cocoons to protect themselves during pupation.
Weaver ants use silk to connect leaves together to make communal nests.
Caddisfly larvae produce silk.
Webspinners have silk glands on their front legs.
Hornets
Silverfish
Mayflies
Thrips
Leafhoppers produce silk nests under the leaves of the trees where they live, to protect them against predators.
Beetles
Lacewings
Fleas
Flies
Midges
Caterpillars of many butterfly species use silk to create shelters or attach to substrates for pupation.
Parasitic wasps such as braconids use silk cocoons for pupation.
Other animals
The family Projapygidae in the order Diplura have cerci that contain silk glands.
The mussel Pinna nobilis creates silk to bond itself to rocks. It is used to make sea silk.
Spiders make spider silk for various purposes such as weaving their webs, protecting their eggs or as a safety line.
The amphipod Peramphithoe femorata uses silk to make a nest out of kelp blades. Another amphipod, Crassicorophium bonellii, use silk to build shelter.
Carp produce fibroin units, a component of silk, to attach their eggs to rocks.
Spider mites make webs that protects them against predators.
Symphyla produce silk through a pair of spinnerets, which is used for nest building, escape and defense.
Pseudoscorpions make silk chambers in which they molt.
Goats have been genetically modified to produce milk containing extractable silk proteins.
Dulichia rhabdoplastis
References
External links
US National Library of Medicine, National Institutes of Health, documentation about various animals that produce silk and why.
Animals
Silk
silk | List of animals that produce silk | [
"Biology"
] | 420 | [
"Lists of biota",
"Lists of animals",
"Animals"
] |
42,982,295 | https://en.wikipedia.org/wiki/Penicilloic%20acid | Penicilloic acid is any of several acids which are obtained from the penicillins by the hydrolytic opening of the lactam ring (as by the action of a beta-lactamase).
Hypersensitivity is the most important adverse effect of the penicillins. The major antigenic determinant of penicillin hypersensitivity is its metabolite, penicilloic acid, which reacts with proteins and serves as a hapten to cause an immune reaction.
Approximately five percent of patients have some kind of reaction, ranging from maculopapular rash (the most common rash seen with ampicillin hypersensitivity) to angioedema (marked swelling of the lips, tongue, and periorbital area) and anaphylaxis. Among patients with mononucleosis who are treated with ampicillin, the incidence of maculopapular rash approaches 100 percent.
Cross-allergic reactions occur among the β-lactam antibiotics. To determine whether treatment with a β-lactam is safe when an allergy is noted, patient history regarding severity of previous reaction is essential.
References
Human drug metabolites
Thiazolidines
2,3-Diaminopropionic acids
Dicarboxylic acids
Formamides
Secondary amino acids | Penicilloic acid | [
"Chemistry"
] | 271 | [
"Chemicals in medicine",
"Molecular biology stubs",
"Human drug metabolites",
"Molecular biology"
] |
42,982,817 | https://en.wikipedia.org/wiki/Matsusaka%27s%20big%20theorem | In algebraic geometry, given an ample line bundle L on a compact complex manifold X, Matsusaka's big theorem gives an integer m, depending only on the Hilbert polynomial of L, such that the tensor power Ln is very ample for n ≥ m.
The theorem was proved by Teruhisa Matsusaka in 1972 and named by Lieberman and Mumford in 1975.
The theorem has an application to the theory of Hilbert schemes.
Notes
Algebraic geometry | Matsusaka's big theorem | [
"Mathematics"
] | 94 | [
"Theorems in algebraic geometry",
"Theorems in geometry"
] |
42,982,848 | https://en.wikipedia.org/wiki/Salt%20marsh%20die-off | Salt marsh die-off is a term that has been used in the US and UK to describe the death of salt marsh cordgrass leading to subsequent degradation of habitat, specifically in the low marsh zones of salt marshes on the coasts of the Western Atlantic. Cordgrass normally anchors sediment in salt marshes; its loss leads to decreased substrate hardness, increased erosion, and collapse of creek banks into the water, ultimately resulting in decreased marsh health and productivity.
Die-off can affect several species of cordgrass (genus Spartina), including S. alterniflora, S. densiflora, and S. townsendii. There are several competing hypotheses predicting the causes and mechanisms of salt marsh die-off throughout the western Atlantic. These hypotheses place different emphasis on the effects of top-down or bottom-up processes for salt marsh die-off. Combined with salt marsh dieback of the high marsh, salt marsh die-off is a serious threat to the ecosystem services that marshes provide to local coastal communities.
History of top-down vs. bottom-up
In light of their effect on community processes, behaviors, and ecological interactions, consumptive interactions are some of the most widely studied concepts in ecology. Because of this, scientists use food webs to depict all of the food chains and trophic relationships in an ecological community.
Food webs can be controlled by bottom-up or top-down forces, which dictate whether a food web's structure and population dynamics are regulated by nutrients (a supply of fixed carbon) and primary production or by top predators, respectively.
Much energy is lost from one trophic level to the next (about 90%); therefore, the success of higher levels is linked to lower ones and their supply of resources (Lindeman 1942). However, the abundance and distribution of organisms in an ecosystem is also affected by densities of consumers, which limit the success of organisms at lower trophic levels and thereby influence the abundance of these organisms (Hairston et al. 1960).
Many ecologists argue that bottom-up and top-down control do not play equally critical roles in the structure and dynamics of populations in an ecosystem; however, data suggests that both bottom-up and top-down forces impact the structure of food webs and the spatial and temporal abundance and distribution of organisms (Bertness 2007), although to what extent each plays a role is not fully understood.
Historically, an emphasis on bottom-up control in many ecosystems has prevailed in ecological thought, often to the exclusion of consumer control (Strong 1992). Many ecosystems in which consumer control has classically been considered trivial are dominated by plants (e.g., forests, grasslands, and salt marshes) and are usually green in appearance. Hairston and colleagues proposed an opposing view in 1960 that emphasized consumer control. They argued that the “world is green” because higher trophic levels regulate herbivore abundance (Hairston et al. 1960).
Critics pointed out that the world is not always green, and that when it is, herbivores do not necessarily play an important role in structuring plant communities (Ehrlich and Birch 1967). Others argued that what is green is not always edible or of sufficiently high quality to allow increases in herbivore populations (Dixon 1966, Murdoch 1966). The debate is ongoing, but the dominant view of ecologists remains that although consumers affect many aspects of plant productivity and ecology, top-down control does not drive the productivity of entire plant ecosystems.
More recently, however, examples of conspicuous consumer control of entire ecosystems have emerged in a variety of habitats including lakes (Carpenter et al. 1985), rivers (Power 1992), and marine (Estes and Duggins 1995) habitats. Foundation plant species can be replaced with other species or substratum completely lacking vegetation and insects can defoliate whole mangroves (Feller 2002).
A classic example of top-down interactions dictating community structure and function comes from Bob Paine's work in Washington, which established that removal of the starfish Pisaster triggered a trophic cascade in which the blue mussel (Mytilus) populations exploded due to release from predation pressure (Paine 1966)
Another influential example of top-down control emerged from Jane Lubchenco's experiments on New England rocky shores, which demonstrated that the herbivorous snail L. littorea exerts control on the diversity and succession of tide pool algal communities (Lubchenco and Menge 1978). One hypothesis that arose from Lubchenco's work (Little and Kitching 1996) was that predation by the green crab (Carcinus maenas) influences rocky shore algal communities by regulating L. littorea abundances.
Ecologists cite these examples as evidence that consumer regulation is more potent and predominant than previously recognized.
Historical paradigms of salt marsh theory
In salt marshes, early ecologists like Eugene Odum and John Teal sparked the current bottom-up paradigm in ecology through work on Sapelo Island, GA (U.S.A) that stressed the dominant role of physical factors like temperature, salinity, and nutrients in regulating plant primary productivity and ecosystem structure (Teal 1962, Odum 1971). Ecologists noted that marsh plants were not heavily grazed and appeared to be relatively unpalatable, and thus argued that most plants entered salt marsh food chains as detritus (Teal 1962). A corollary of this dogma is that consumers play an unimportant or subtle role in controlling salt marsh primary production (Smalley 1960, Teal 1962). This paradigm was widely accepted for decades and applied to other ecosystems like mangroves and seagrass beds (Bertness 2007), and has thus “become entrenched in the conceptual understanding of coastal ecosystems” (quote from Bertness and Silliman 2008; Smalley 1960, Nixon 1982).
Recent work, however, has demonstrated strong top-down control of plant communities in salt marshes by a wide variety of consumers, including snails, crabs, and geese (Jefferies 1997, Bortolus and Iribarne 1999, Silliman and Bertness 2002, Holdredge et al. 2009). Marsh grazers also include feral horses (Furbish and Albano 1994), cattle, hares, insects, and rodents, some of which are able to strongly suppress plant growth.
Strong top-down control on marshes has been demonstrated in various marsh systems. Consumer control is driven by the grapsid crab (Chasmagnathus granulata) in the salt marshes of Argentina and Brazil on the Atlantic coast of South America (Bortolus and Iribarne 1999). Other experiments in Argentina have contributed to the growing body of work evidencing consumer control in salt marshes (Alberti et al. 2007), and herbivory has also been suggested to play an important role in southwestern Atlantic marshes (Bortolus and Iribarne 1999, Alberti et al. 2007). Not only are consumers important on a small scale as demonstrated by cage experiments in various locations (Silliman and Zieman 2001, Silliman and Bertness 2002, Silliman et al. 2005), but they also affect primary productivity across large geographic areas (Silliman and Zieman 2001).
Bertness and Silliman have also suggested that while salt marshes may have historically been nutrient limited and bottom up controlled, human disturbances such as eutrophication and predator depletion has shifted these systems to top down control in recent decades (Bertness and Silliman 2008).
Regional causes of salt marsh die-off
Both top-down and bottom-up forces have been proposed as primary drivers of salt marsh die-off throughout the western Atlantic. The relative importance of these factors depends on the abiotic and biotic conditions of each local or regional marsh system and its environment.
Top-down interactions
Human activities can trigger trophic cascades (Jefferies 1997), which occur when the predators that limit abundance of prey and thereby enhance survival of the next lower trophic level are depleted (Strong 1992). Depletion of top predators releases their prey from consumer control and leads to population declines of the next lower trophic level, often the primary producers. Trophic cascades occur across a minimum of three trophic levels and can impact community dynamics in a variety of systems (Estes et al. 1998). Trophic cascades can induce salt marsh die-off and transform green landscapes into barrens (Estes and Duggins 1995, Silliman et al. 2005). Primary triggers of trophic cascades through human action include introduction of invasive species, overexploitation, and climate change (Jackson et al. 2001, Lotze et al. 2006, Gedan et al. 2009, Gedan and Bertness 2011).
Invasive species
Human introduction of non-native species can also contribute to top-down control of marsh systems (Furbish and Albano 1994, Gough and Grace 1998). Introduced feral horses on the barrier islands of Maryland, Virginia, and the Carolinas have entirely denuded marsh ecosystems (Furbish and Albano 1994), and the introduced rodent nutria on Gulf Coast marshes of Louisiana can decrease marsh plant primary production (Gough and Grace 1998).
The invasive green crab, Carcinus maenas, can turn off top down control by facilitating the recovery of salt marsh ecosystems. In marshes that have experienced die-off via the trophic cascade initiated by recreational overfishing, purple marsh crabs, Sesarma reticulatum, can be evicted by the larger green crabs, which prey upon the purple crab. In this way, green crabs can indirectly reduce purple crab herbivory and promotes cordgrass recovery. These results are encouraging because they suggest that invasive species, which are classically considered to have mostly negative impacts on the ecosystems they invade, can sometimes actually contribute to restoring degraded ecosystems.
Fungal
Die-off could potentially be explained by pathogens of salt marsh plants in some areas – fungal species have been identified at die-off sites in the UK as well as US Atlantic and Gulf coast sites (Elmer 2013). Fungal-facilitated marsh degradation is a documented concern in the Southeast Atlantic in particular. Marsh snails Littoraria irrorata make minor cuts in the cordgrass during grazing. These cuts facilitate growth of fungus, and at high snail densities, can lead to mass infections, increased grazing and consequent die-off (Silliman and Bertness 2002, Silliman and Newell 2003, Silliman et al. 2005).
In coastal New England, this evidence is weaker. Certain fungal pathogens of S. alterniflora were found more frequently in sites of die-off. These pathogens have varying degrees of virulence, and there is some evidence of association with species of Fusarium and areas of die-off. However, although the association suggests a partial causal link, particularly in stress-predisposed plants, strong evidence is lacking to suggest that such fungal pathogens are a major cause of die-off in New England (Elmer 2013).
Overexploitation
Overharvesting has led to the collapse of various shallow-water marine ecosystems around the globe (Jackson et al. 2001), including coral reefs (Hughes et al. 2003), sea grass beds, and kelp forests (Estes et al. 1998).
Commercial fishing
Research on the salt marsh snail Littoraria irrorata and its effects on marsh plant productivity, have provided strong evidence of consumer control in marshes triggered by overexploitation. This snail is capable of turning strands of cordgrass (Spartina alterniflora) (>2.5m tall) into mudflats within 8 months, which is less than one growing season (Silliman and Bertness 2002). As previously referenced, marsh snails inflict cuts on cordgrass leaves when they graze, providing substratum and nutrients for fungus. At high snail densities, cordgrass can succumb to fungal infections and marsh die-off can ensue (Silliman and Bertness 2002, Silliman and Newell 2003, Silliman et al. 2005). Natural predators of the marsh snail are blue crabs (Callinectes sapidus) and terrapin turtles (Malaclemys terrapin), which historically regulated snail abundances. However, these predators have been commercially overexploited, and now suffer from diseases due to small population size, releasing the snails from consumer pressure, and allowing the snails to wreak havoc on salt marsh cordgrass populations (Silliman and Zieman 2001).
A classic example of a trophic cascade was caused by the overexploitation of sea otters in the 1980s (Estes & Duggins 1995). Sea otters eat urchins, which in turn graze on macroalgae in a food chain that, when altered, can lead to urchin barrens. Sea otters in Alaska were hunted to near extinction for their pelts. Where sea otter populations have persisted, they suppress the abundance of urchins and thus have an indirect positive effect on the density of macroalgae. In contrast, in sites where sea otters are absent, sea urchin populations have surged and caused urchin barrens to develop. Wherever sea otters have been reinstated, sea urchin populations have been reduced, and kelp densities have increased, returning the habitat to its original healthy state. This example demonstrates the potential for whole-ecosystem recovery with the reestablishment of consumers (Estes and Duggins 1995).
Other trophic cascades, such as those caused by crabs such as Chasmagnathus granulata in South America, are at least in part due to overfishing of top predators (Bortolus and Iribarne 1999, Alberti et al. 2007).
Recreational fishing
In New England, predator depletion has triggered extensive marsh die-off salt marsh creek banks. Herbivory has already impacted up to 90% of creek banks in more than 70% of outer Cape Cod marshes. Absent in 1997, die-off has recently spread into Narragansett Bay, Rhode Island, impacting over 85% of creek banks. The nocturnal purple marsh crab, Sesarma reticulatum, is playing a major role in this die-off through increased burrowing and herbivory due to release from predation pressure. Evidence has pointed to top-down control caused by human disturbances as the primary agent driving die-off.
Altieri and colleagues performed a series of experiments (Altieri et al. 2012) designed to elucidate the mechanisms driving marsh die-off more specifically. Sesarma crabs are normally preyed upon by blue crabs (Callinectes sapidus), and fish including striped bass (Morone saxatilis) and smooth dogfish (Mustelus canis). Although the cascading effects of overfishing have been demonstrated across various ecosystems (Myers and Worm 2003), research on predator depletion has focused almost exclusively on the impact of large-scale commercial overfishing (Worm et al. 2009). However, Altieri and colleagues (2012) demonstrated that the predators of Sesarma were, and continue to be, overexploited by recreational anglers. Their results show that die-off and vegetated marshes differed dramatically in recreational fishing pressure, as anglers were observed only at die-off sites.
Die-off marshes had half the biomass of top-level predators found at vegetated sites, while the biomass of nonharvested consumers did not differ between die-off and vegetated sites. Additionally, the predation rate on Sesarma at vegetated sites was triple that of die-off sites, and crabs consumed four times more grass at die-off sites than at vegetated sites. Historical reconstructions showed that little net marsh loss (<5%) from 1939 to 2005 occurred at currently vegetated sites. In contrast, die-off marshes exhibited the onset of die-off in the mid-70s, with consistently increasing vegetation loss through 2005, at which time >20% of the total marsh area was lost to die-off and >80% of the cordgrass zone was unvegetated. This divergence between die-off and vegetated marshes in vegetation loss coincides with a period of rapid increase in the number of docks and boat slips before the mid-70s that resulted in the establishment of >70% of that fishing infrastructure currently present at die-off marshes. These results provide evidence that Sesarma release from predation pressure by crabs and fish due to recreational overfishing by anglers is driving a trophic cascade that is responsible for extensive marsh die-off throughout southern New England (Altieri et al. 2012).
Altieri and colleagues (2012) further hypothesized that historic, large-scale, industrialized overexploitation of fish in the northwest Atlantic (Lotze et al. 2006) increased marsh vulnerability to the effects of localized recreational fishing to the point that large-scale die off ensued, and that resultant localized die-offs could coalesce into complete, region-wide marsh die-off if overexploitation of top consumers continues (Altieri et al. 2012).
Most recently, Bertness and colleagues (Bertness et al. 2014b) performed a field experiment excluding predators from plots on the grazing border of the marsh. Within one growing season, exclusion of top predators triggered die-off by increasing the abundances of Sesarma crabs and the intensity of herbivory. To further test the trophic cascade hypothesis, Bertness and colleagues used the spread of die-off into Narragansett Bay to assess all proposed drivers of die-off, including: 1) eutrophication decreases plant investment into belowground biomass causing plant collapse, 2) boat wakes erode creek banks, 3) pollution or disease affect plant health, 4) substrate hardness controls herbivorous crab distributions and 5) trophic dysfunction releases Sesarma from predator control. Nitrogen availability, wave intensity and plant growth did not explain any variation in die-off. However, herbivory explained over 70% of inter-site variation in die-off. (Bertness et al. 2014a) This work highlighted one particular example where top-down interactions were experimentally shown to be the primary driver of ecological community state change.
Bottom-up interactions
Hypersaline and anoxic soils
One theory of bottom-up control lies with differential soil chemistry between vegetated and die-off areas. Drought-associated changes in soil chemistry have been proposed to be associated with areas of die-off. Droughts are often associated with increased salinity and acidity stress – soils oxidize under freshwater or tidal moisture limitation, leading to increased acidity. Hypersalinity has been linked to reduced S. alterniflora survival (Brown et al. 2005). However, salt marsh plants are generally tolerant of a broad range of salinity levels, and increased salinity has not consistently been observed in die-off sites (Alber et al. 2008).
There is uncertainty attributed to the link between different soil conditions and sites of die-off for several reasons. First, measurements may not be taken in frequent enough intervals to capture brief fluctuations in soil conditions associated with die-off. Second, attributing causation with changing soil conditions and die-off is potentially dubious. Reverse causality is a potential explanation; that is, soil chemistry differences may be a result rather than an agent of die-off. For instance, one study noted higher salinity levels in die-off areas in some months, but this was possibly attributable to altered root or evaporation dynamics due to die-off (Marsh 2007).
Eutrophication
Nutrient enrichment is a pervasive global threat to both marine and terrestrial ecosystems (Galloway et al. 2008, Verhoeven et al. 2006). In marine ecosystems, increased flow of nitrogen can trigger severe algal blooms, anoxic conditions, and widespread fisheries losses (Diaz & Rosenberg 2008). In salt marshes, an important interface ecosystem between land and sea, nutrient addition has been hypothesized to contribute to widespread creek die-offs (Deegan et al. 2012).
To test this hypothesis, Linda Deegan and colleagues performed a nine-year study at one site in Massachusetts. The researchers found that tidal creek enrichment of nitrogen and phosphorus led to decreased investment in belowground nutrient gathering roots and rhizomes, increased microbial decomposition of organic matter, and eventual creek collapse and salt marsh loss (Deegan et al. 2012).
Similar studies in Connecticut, however, have been unable to replicate these findings. Shimon Anisfeld and Troy Hill performed a 5-year fertilization experiment of a salt marsh in Long Island Sound and found that neither nitrogen nor phosphorus fertilization led to elevation loss, reduced soil carbon, or a decrease in belowground primary production. They suggest that high nutrient levels can significantly alter marsh processes and increase gross carbon loss from sediment but that other processes may compensate for these impacts. No net deleterious effects of nutrient loading on carbon storage or on marsh stability are anticipated from this study (Anisfeld and Hill 2012).
Other eutrophication studies performed in Narragansett Bay, Rhode Island found that experimental nitrogen addition initially increases plant productivity but eventually leads to reduced plant biomass due to insect herbivory (Bertness et al. 2008). To supplement this experiment, researchers took surveys across 20 salt marshes to look at the interaction between marsh nutrient levels and herbivore pressure and found that marsh nitrogen supply was a good predictor of herbivore damage to plants. This study suggests that eutrophication is currently triggering consumer suppression of primary productivity in New England salt marshes and may eventually pose a threat to salt marsh ecosystem service provisioning (Bertness et al. 2008).
Potential for Synergistic effects
Coastal ecosystems suffer from a variety of anthropogenic impacts, such as large-scale eutrophication, food web alteration, runaway consumer effects, climate change, habitat destruction, and disease. Rarely do these factors act in isolated ways. Often, researchers find additive or synergistic interactions between impacts compounding the amount of ecosystem degradation. One such example is found in salt marshes in the southeastern United States. Depletion of top predators in these systems has led to snail overgrazing of salt marsh cordgrass and subsequent die-off (as explained above). However, this die-off has been linked with intense drought conditions and the resultant increases in salt and acid stress (Silliman et al. 2005). Drought stress that raises soil salinities and increases cordgrass vulnerabilities to top-down control may be a product of climate change (Silliman and Bertness 2002, Silliman et al. 2005). Cases such as these highlight how abiotic and biotic interactions can interact to affect ecosystem health.
Anthropogenic actions also can cause eutrophication, or increase the nutrient load, of marine ecosystems, through runoff into the system containing fertilizer, sewage, dishwasher soap, and other nitrogen- and phosphorus-rich substances. Eutrophication is pervasive in coastal marine ecosystems (Lotze et al. 2006) and can indirectly initiate trophic cascades and increase consumer control of plants. For example, insect herbivory in marshes has been positively correlated with nutrient availability in Atlantic salt marshes (Bertness et al. 2008). In Narragansett Bay, insect herbivory suppresses primary production of human disturbed salt marshes by almost 40%. Nitrogen additions through human activity can increase insect herbivory so much that primary production is suppressed by nearly 60%, while marshes without human shoreline development remain solely under bottom-up control (Bertness et al. 2008). Increased nutrient supply can lead to runaway herbivory in other systems as well (Gough and Grace 1998, Silliman and Zieman 2001).
For example, eutrophication initiates top-down control via the impact of snow geese on the arctic marshes of Hudson Bay (Jefferies 1997). By the 1980s, the snow geese that originally annually migrated to Hudson Bay had switched from feeding in temperate wetlands to feeding in heavily fertilized agricultural fields. Over a period of 30 years, the geese population exploded. Snow geese have since utterly destroyed hundreds of thousands of acres of the Hudson Bay wetland. The geese grubbed marsh plant roots, evaporation increased leading to subsequent salinity increase, and without plants to oxygenate the soil the substrate became anoxic. This undesirable environment for marsh plants disallows sexual recruitment to the area. Snow geese have denuded the marsh until recolonization by clonal runners can restore marsh vegetation, which could take years. Because of the use of artificial fertilizers on temperate zone agricultural fields, a trophic cascade was initiated (Jefferies 1997).
A major goal of ecology over the next century will be to understand how ecosystems will respond to current and future human impacts and the additive or synergistic interactions between them.
Management implications and conservation
Ecosystem services are the benefits that humans derive from ecological systems. Today, one of the arguments for protecting salt marshes is to increase the quality and quantity of these services. Salt marshes sequester nitrogen, filtering runoff water and reducing nitrogen input to estuaries (Valiela and Cole 2002). Salt marshes also provide essential refuge habitat for young fish and crustaceans, provisioning coastal fisheries (Boesch and Turner 1984) that account for 90% of the world's fish catch (UNEP 2006). Salt marshes also sequester carbon, which will be an important ecosystem service as climate change intensifies (Chmura et al. 2003). Arguably the most important ecosystem service salt marshes provide is to act as natural sea barriers because grasses bind soils, prevent shoreline erosion, attenuate waves, and reduce coastal flooding (Costanza et al. 2008).
However, the marsh's natural ability to buffer against erosion and flooding may be reduced by creek bank die-off. Since Spartina alterniflora is responsible for sediment binding and peat deposition (Redfield 1965), cordgrass die-off may compromise the ability of salt marshes to keep pace with sea-level rise. Also, the concentration of Sesarma burrows in New England salt marsh peat may directly trigger the erosion and collapse of the peat foundation of marshes.
On Cape Cod, marsh creek banks are often so riddled with Sesarma burrows that they collapse, exposing fresh peat to further burrowing and erosion (Bertness et al. 2008). Feedbacks between crab herbivory and cordgrass die-off may thus lead to the retreat of marsh edges. For example, Coverdale and colleagues found that 20 years of die-off on Cape Cod have resulted in the loss of over 200 years of marsh accretion and hundreds of acres of marsh loss. The detrimental effects trophic cascades have had on marshes not only reduce the biodiversity, health, and aesthetic appeal of these ecosystems, but also compromise the ability of marshes to provide key ecosystem services to human populations.
Conclusions
Despite mounting evidence to the contrary, bottom-up control remains the central dogma determining marsh management, conservation and restoration efforts. Salt marshes are currently managed as if they are exclusively regulated by physical factors. However, global and near shore top predator depletion leading to the release of cryptic or unappreciated herbivores may be the biggest current threat to salt marshes. Theory dependency (subconscious favoring of identifying and/or examining natural phenomena that tend to confirm rather than refute the current paradigm of a study system [Kuhn 1962]) and demonstration, rather than falsifying science, have been the leading culprits in this oversight. Consequently, threats to salt marshes that are governed by top down control are being overlooked, with potentially devastating consequences.
Trophic cascades are powerful interactions that strongly regulate biodiversity, community structure, and ecosystem function. Trophic cascades were originally thought to be rare, but it has become clear that they occur across diverse terrestrial, freshwater, and marine ecosystems at both small and large spatial and temporal scales. Trophic cascades are common and pervasive aspects of many communities long thought to be controlled by bottom-up forces and/or resistant to consumer control.
Conservation of ecosystems affected by trophic cascades has thus not adequately incorporated top-down control into their management and restoration plans and efforts, but emerging research has emphasized that this is necessary to protect the services provided by these ecosystems and to restore these ecosystems to their original conditions. Failure to do so could lead to trophic cascades transforming highly diverse and productive plant communities to barren flats.
Additionally, failure to reevaluate the current paradigm and recognize that both bottom-up and top-down forces affect many features of ecosystem structure and function, and that these forces are complementary rather than contradictory, could bar any incorporation of both mechanisms into any management plan and reduce the success of conservation efforts before they even begin.
References
Salt marshes
Aquatic ecology
Wetland conservation
Wetland conservation in the United States
Ecological processes | Salt marsh die-off | [
"Physics",
"Chemistry",
"Biology"
] | 6,070 | [
"Physical phenomena",
"Earth phenomena",
"Salt marshes",
"Salts",
"Ecological processes",
"Ecosystems",
"Aquatic ecology"
] |
42,983,741 | https://en.wikipedia.org/wiki/Julian%20Parkhill | Julian Parkhill (born 1964) is Professor of Bacterial Evolution in the Department of Veterinary Medicine at the University of Cambridge. He previously served as head of pathogen genomics at the Wellcome Sanger Institute.
Education
Parkhill was educated at Westcliff High School for Boys, the University of Birmingham and the University of Bristol where he was awarded a PhD in 1991 for research into the regulation of transcription of the mercury resistance operon.
Career and research
Parkhill uses high throughput sequencing and phenotyping to study pathogen diversity and variation, how they affect virulence and transmission, and what they tell us about the evolution of pathogenicity and host–pathogen interaction. Research in the Parkill Laboratory has been funded the Wellcome Trust, the Biotechnology and Biological Sciences Research Council (BBSRC) and the Medical Research Council (MRC).
Awards and honours
Parkhill was elected a Fellow of the Academy of Medical Sciences (FMedSci) in 2009, and a Fellow of the American Academy of Microbiology (FAAM) in 2012.
Parkhill was elected a Fellow of the Royal Society (FRS) in 2014, his certificate of election reads:
References
Fellows of the Royal Society
Living people
Academics of the University of Birmingham
Pathogen genomics
People educated at Westcliff High School for Boys
1964 births
Alumni of the University of Birmingham | Julian Parkhill | [
"Biology"
] | 271 | [
"Molecular genetics",
"DNA sequencing",
"Pathogen genomics"
] |
42,984,538 | https://en.wikipedia.org/wiki/Entoloma%20alboumbonatum | Entoloma alboumbonatum is an inedible species of fungus in the agaric genus Entoloma. Found in the United States, it was described by mycologist Lexemuel Ray Hesler in 1967.
See also
List of Entoloma species
References
External links
Entolomataceae
Fungi described in 1967
Fungi of the United States
Inedible fungi
Fungi without expected TNC conservation status
Fungus species | Entoloma alboumbonatum | [
"Biology"
] | 91 | [
"Fungi",
"Fungus species"
] |
56,018,994 | https://en.wikipedia.org/wiki/Mars%20Organic%20Molecule%20Analyser | The Mars Organic Molecule Analyser (MOMA) is a mass spectrometer-based instrument on board the Rosalind Franklin rover to be launched in 2028 to Mars on an astrobiology mission. It will search for organic compounds (carbon-containing molecules) in the collected soil samples. By characterizing the molecular structures of detected organics, MOMA can provide insights into potential molecular biosignatures. MOMA will be able to detect organic molecules at concentrations as low as 10 parts-per-billion by weight (ppbw). MOMA examines solid crushed samples exclusively; it does not perform atmospheric analyses.
The Principal Investigator is Fred Goesmann, from the Max Planck Institute for Solar System Research in Germany.
Overview
The goal of MOMA is to seek signs of past life on Mars (biosignatures) by analysing a wide range of organic compounds that may be found in drilled samples acquired from 2 meters below the Martian surface by the Rosalind Franklin rover. MOMA examines solid crushed samples only; it does not perform atmospheric analyses.
MOMA will first volatilize solid organic compounds so that they can be analysed by a mass spectrometer; this volatilisation of organic material is achieved by two different techniques: laser desorption and thermal volatilisation, followed by separation using four GC-MS columns. The identification of the organic molecules is then performed with an ion trap mass spectrometer.
Organic biosignatures
While there is no unambiguous Martian biosignature to look for, a pragmatic approach is to look out for certain molecules such as lipids and phospholipids that may be forming cell membranes which can be preserved over geological timescales. Lipids and other organic molecules may exhibit biogenic features that are not present in abiogenic organic material. If biogenic (synthesized by a life form), such compounds may be found at high concentrations only over a narrow range of molecular weights, unlike in carbonaceous meteorites where these compounds are detected over a broader range of molecular weights. In the case of sugars and amino acids, excessive molecular homochirality (asymmetry) is another important clue of their biological origin. The assumption is that life on Mars would be carbon-based and cellular as on Earth, so there are expected common building blocks such as chains of amino acids (peptides and proteins) and chains of nucleobases (RNA, DNA, or their analogs). Also, some isomers of high molecular weight organics can be potential biosignatures when identified in context with other supporting evidence. Other compounds targeted for detection will include fatty acids, sterols, and hopanoids.
Background organics
The surface of Mars is expected to have accumulated significant quantities of large organic molecules delivered by interplanetary dust particles and carbonaceous meteorites. MOMA's characterization of this fraction, may determine not only the abundance of this potential background for trace biomarker detection, but also the degree of decomposition of this matter by radiation and oxidation as a function of depth. This is essential in order to interpret the samples' origin in the local geological and geochemical context.
Development
The components of MOMA related to GC-MS have heritage from the Viking landers, the COSAC on board the comet lander Philae, and SAM on board the Curiosity rover. But the methods applied in the past on board the Viking landers and the Curiosity rover are mostly destructive (pyrolysis), and consequently important information of the organic material is lost. Also, only volatile molecules can be detected and, only nonpolar molecules can get through the GC columns to the detector. MOMA will combine pyrolysis–derivatization with a less destructive method: LDMS (Laser Desorption Mass Spectrometry), which allows large and intact molecular fragments to be detected and characterized by the mass spectrometer (MS). The LDMS technique is not affected by these drawbacks, and it is unaffected to the presence of perchlorates, known to be abundant on the surface of Mars. Tandem mass spectrometry can then be used to further characterize these molecules.
The Max Planck Institute for Solar System Research is leading the development. International partners include NASA. The mass spectrometer (MS) and the main electronics of MOMA are provided by NASA's Goddard Space Flight Center, while the gas chromatography (GC) is provided by the two French institutes LISA and LATMOS. The UV-Laser is being developed by the Laser Zentrum Hannover. MOMA does not form a single compact unit, but is modular with numerous mechanical and thermal interfaces within the rover. The final integration and verification will be performed at Thales Alenia Space in Italy.
References
External links
(NASA; 24 May 2018))
ExoMars
Spacecraft instruments
Astrobiology
Space science experiments | Mars Organic Molecule Analyser | [
"Astronomy",
"Biology"
] | 1,009 | [
"Origin of life",
"Speculative evolution",
"Astrobiology",
"Biological hypotheses",
"Astronomical sub-disciplines"
] |
56,019,069 | https://en.wikipedia.org/wiki/Stannylene | Stannylenes (R2Sn:) are a class of organotin(II) compounds that are analogues of carbene. Unlike carbene, which usually has a triplet ground state, stannylenes have a singlet ground state since valence orbitals of tin (Sn) have less tendency to form hybrid orbitals and thus the electrons in 5s orbital are still paired up. Free stannylenes are stabilized by steric protection. Adducts with Lewis bases are also known.
History
The first persistent stannylene, [(Me3Si)2CH]2Sn, was reported by Michael F. Lappert in 1973. Lappert used the same synthetic approach to synthesize the first diamidostannylene [(Me3Si)2N]2Sn in 1974.
The short-lived, transient stannylene Me2Sn has been generated by thermolysis of cyclo-(Me2Sn)6.
Synthesis and characterization
Persistent stannylene
Most alkyl stannylenes have been synthesized by alkylation of tin(II) dihalides with organolithium reagents. For example, the first stannylene, [(Me3Si)2CH]2Sn, was synthesized using (Me3Si)2CHLi and SnCl2.
In some cases, stannylenes have been prepared by reduction of a tin(IV) compound by KC8
Amidostannylene can also be synthesized by using a tin(II) dihalide and the lithium amide.
Short-lived stannylene
The isolation of a transient alkyl stannylene is more difficult. The first isolation of dimethylstannylene was believed to be done by thermolysing cyclostannane (Me2Sn)6, which was the product of the condensation of Me2Sn(NEt2)2 and Me2SnH2. The evidence came from the vibrational frequencies of dimethylstannylene identified by infrared spectroscopy, which is consistent with the calculated value. The existence of this elusive SnMe2 was further confirmed by the discovery of visible light absorption matching the calculated electronic transition of SnMe2 in gas phase.
Another method to prepare short-lived stannylene is laser flash photolysis using tetraalkyltin(IV) compound (e.g. SnMe4) as a precursor. The generation of stannylene can be monitored by transient UV-VIS spectroscopy.
Structure and bonding
Stannylenes can be viewed as sp2-hybridized with vacant 5p orbital and a lone pair. This gives rise to their red color from n to p transition.
With specific type of ligands, the electron deficiency of monomeric stannylene is reduced by the agostic interaction from B-H bond. This concept was proved by Mark Kenyon and coworkers in 2006 when they synthesized the cyclic dialkylstannylene [{n-Pr2P(BH3)}(Me3Si)CCH2]2Sn. The crystal structure of the synthesized compound showed the arrangement of one B-H bond toward the Sn atom with the B—H--Sn bond distance of 2.03 Å. The mitigation of Sn electron deficiency was proved by the spectroscopic data, especially the 119Sn NMR spectra which showed the drastically low chemical shift (587 and 787 ppm comparing to 2323 ppm in analogous dialkylstannylene) indicating more electron density around Sn in this case.
Reactivity
Oligomerization
Small, unstable stannylenes (e.g. dimethylstannylene) undergo self-oligomerization yielding cyclic oligostannanes, which can be used as stannylene sources.
More bulky stannylenes (e.g. Lappert's stannylene), on the other hand, tend to form a dimer. The nature of the Sn-Sn bond in stannylene dimer is rather different from C-C bond in carbene dimer (i.e. alkene). As alkene develops a typical double bond character and the molecule has a planar geometry, stannylene dimer has a trans-bent geometry. The double bond in stannylene dimer can be considered as two donor-acceptor interactions. The electron localization function (ELF) analysis of stannylene dimer shows a disynaptic basin (electrons in bonding orbitals) on both Sn atom, indicating that the interaction between two Sn atom is two unusual bent dative bonds. Apart from that, the stability of stannylene dimer is also affected by the steric repulsion and dispersion attraction between bulky substituents.
Insertion reaction
Alkylstannylenes can react with various reagents (e.g. alkyl halides, enones, dienes) in an oxidative addition (or insertion) fashion. The reaction between stannylene and 9,10-phenanthrolinedione produces an EPR signal that was identified to be 9,10-phenanthrenedione radical anion, indicating that this reaction proceeds via radical mechanism.
Cycloaddition
Although stannylenes are more stable than its lighter carbene analogs, they readily undergo [2+4] cycloaddition reaction with Z-alkenes. The addition of (CH(SiMe3)2)2Sn, to 2,7-diphenylocta-2,3,5,6-tetraene proceeds in a cheletropic fashion, as allowed by Woodward-Hoffmann rules.
Metal center for oxidative addition and reductive elimination
In terms of the SnII/SnIV couple, certain stannylenes resemble transition metals. The singlet-triplet energy separation is considered to have a strong effect on oxidative addition reactivity, by utilizing a very strong σ-donor boryl (-BX2) ligand. The results demonstrated that not only molecular hydrogen but also E-H bond (E = B, Si, O, N) can be oxidative added on Sn. In ammonia and water cases, the oxidative added product could also undergo reductive elimination, yielding O- or N-B bond formation.
See also
Carbene analogs
Silylene
References
Organotin compounds
Tin(II) compounds
Substances discovered in the 1970s | Stannylene | [
"Chemistry"
] | 1,381 | [
"Functional groups",
"Octet-deficient functional groups"
] |
56,019,210 | https://en.wikipedia.org/wiki/WS-124A%20Flying%20Cloud | Weapon System 124A, given the codename Flying Cloud, was a project of the United States Air Force to use high-altitude balloons to deliver bombs and weapons of mass destruction on enemy targets. Tested in late 1954, the project was found to be unfeasible from the standpoint of accuracy, and the project was terminated the following year.
Design and development
Alongside the WS-119L program to develop long-distance, high-altitude balloons for aerial reconnaissance, the United States Air Force initiated WS-124A in early 1953 to develop a method of delivering weaponry to targets in the Soviet Union using hydrogen balloons; such a capability was considered potentially valuable in the event of a limited nuclear conflict, or in a "broken-back" scenario following a massive nuclear exchange.
The WS-124A balloons were intended to fly at altitudes of roughly , within the jet stream; as weather forecasts were considered to be sufficiently accurate to forecast approximately three days of wind patterns, the design flight duration was for 60 hours, in which they were expected to cover a distance of . The WS-124A balloon was designed to be capable of launching in wind speeds of up to .
It was accepted that there would be an inherent inaccuracy in the concept; the expected target area was by , which was considered acceptable as the designed payloads involved chemical and biological weaponry, although incendiary bombs, for starting forest fires, were also considered as a payload. It was believed that releasing chemical or biological agents from the balloons could contaminate an area "comparable in size to that affected by a low-yield nuclear weapon". Some sources claim that dirty bombs were also considered for carriage by WS-124A. In addition, the ability of the balloons to spread propaganda leaflets across enemy territory was considered useful.
Operational history
Flight tests of the WS-124A balloon system started on 8 October 1954; by 13 December, 41 balloons had been launched, 25 of which were fully operational test flights. Even allowing for the expected inaccuracy, however, only six of the balloons reached their intended target area, while five more were considered to be close enough. This was not considered an acceptable level of accuracy, and in August 1955 the WS-124A program was cancelled, the conclusion being that the weather forecasts were simply not accurate enough for the system to be operationally feasible. In addition, the advent of thermonuclear weapons had made the "broken-back war" scenario WS-124A was intended for appear an impossibility.
See also
Fire balloon
Bat bomb
References
Citations
Bibliography
Chemical weapon delivery systems
Biological weapon delivery systems
Balloon weaponry
Abandoned military projects of the United States
Aircraft first flown in 1954
United States biological weapons program
Chemical weapons of the United States | WS-124A Flying Cloud | [
"Chemistry"
] | 564 | [
"Chemical weapon delivery systems",
"Chemical weapons"
] |
56,019,591 | https://en.wikipedia.org/wiki/Ardisia%20oligantha | Ardisia oligantha is a name which has been given to several species of plants:
Ardisia oligantha , described in 1885, now known as Oncostemum oliganthum
Ardisia oligantha , described in 1902, an illegitimate later homonym
Ardisia oligantha , described in 1912, an illegitimate later homonym replaced by Ardisia oligocarpa
Ardisia oligantha , combined in 1979, an illegitimate later homonym replaced by Ardisia marcellanum
oligantha | Ardisia oligantha | [
"Biology"
] | 114 | [
"Set index articles on plants",
"Set index articles on organisms",
"Plants"
] |
56,020,154 | https://en.wikipedia.org/wiki/Microbivory | Microbivory (adj. microbivorous, microbivore) is a feeding behavior consisting of eating microbes (especially bacteria) practiced by animals of the mesofauna, microfauna and meiofauna.
Microbivorous animals include some soil nematodes, springtails or flies such as Drosophila sharpi. A well known example of microbivorous nematodes is the model roundworm Caenorhabditis elegans which is maintained in culture in labs on agar plates, fed with the 'OP50' Escherichia coli strain of bacteria.
In food webs of ecosystems, microbivores can be distinguished from detritivores, generally thought playing the roles of decomposers, as they don't consume decaying dead matter but only living microorganisms.
Use of term in robotics
There is also use of the term 'microbivore' to qualify the concept of robots autonomously finding their energy in the production of bacteria. Robert Freitas has also proposed microbivore robots that would attack pathogens in the manner of white blood cells.
See also
Bacterivore
References
External links
Biological interactions
Animals by eating behaviors
Ethology
Eating behaviors
Microorganisms | Microbivory | [
"Biology"
] | 263 | [
"Behavior",
"Biological interactions",
"Animals by eating behaviors",
"Eating behaviors",
"Behavioural sciences",
"nan",
"Ethology",
"Microorganisms"
] |
56,022,226 | https://en.wikipedia.org/wiki/European%20Data%20Protection%20Board | The European Data Protection Board (EDPB) is a European Union independent body with juridical personality whose purpose is to ensure consistent application of the General Data Protection Regulation (GDPR) and to promote cooperation among the EU’s data protection authorities. On 25 May 2018, the EDPB replaced the Article 29 Working Party.
Tasks
The EDPB remit includes issuing guidelines and recommendations, identifying best practices related to the interpretation and application of the GDPR, advising the European Commission on matters related to the protection of personal data in the European Economic Area (EEA), and adopting opinions to ensure the consistency of application of the GDPR by the national supervisory authorities, in particular on decisions having cross-border effects. Additionally, the EDPB is tasked with acting as a dispute resolution body in case of dispute between the national authorities cooperating on enforcement in the context of cross-border cases, encouraging the development of codes of conduct and establishing certification mechanisms in the field of data protection, and promoting cooperation and effective exchange of information and good practices among national supervisory authorities.
Chairmanship
The European Data Protection Board is represented by its Chair who is elected from the members of the Board by simple majority for a five-year term, renewable once. The same election procedure and term of office apply to the two deputy chairs.
Currently, the Chairmanship of the Board is held by:
Anu Talus, Chair,
Irene Loizidou Nicolaidou, Deputy Chair
Aleid Wolfsen, Deputy Chair
Members
The Board is composed of representatives of the 27 EU and 3 EEA EFTA national data protection authorities and the European Data Protection Supervisor (EDPS).
References
External links
EDPB official website
European Commission website on the EDPB
European Union official website, EDPB
The EDPB data protection guide for small business
European Union law
Information privacy | European Data Protection Board | [
"Engineering"
] | 376 | [
"Cybersecurity engineering",
"Information privacy"
] |
56,022,379 | https://en.wikipedia.org/wiki/Wildlife%20Monographs | The Wildlife Monographs is a peer-reviewed scientific journal devoted to the ecology of non-domesticated animal species. It is published by John Wiley & Sons on behalf of The Wildlife Society.
See also
Journal of Wildlife Management
Wildlife Society Bulletin
External links
Academic journals established in 1958
Ecology journals
English-language journals | Wildlife Monographs | [
"Environmental_science"
] | 62 | [
"Environmental science journals",
"Ecology journals",
"Environmental science journal stubs"
] |
56,022,486 | https://en.wikipedia.org/wiki/VqmR%20sRNA | VqmR small RNA was discovered in Vibrio cholerae, a bacterium which can cause cholera, using differential RNA sequencing (sRNA-seq) under conditions of low and high cell density which were being used to study quorum sensing (QS). QS controls virulence and biofilm formation in Vibrio cholerae; it has been shown previously that it is directed by the Qrr sRNAs. VqmR has been shown to repress the expression of multiple mRNAs including the rtx (repeats in toxin) toxin genes and the , which is required for biofilm formation. In fact, VqmR which is highly conserved in vibrionaceae, was shown to strongly inhibit biofilm formation by repressing the gene; it could be the link between biofilm formation and QS.
References
Non-coding RNA | VqmR sRNA | [
"Chemistry"
] | 178 | [
"Biochemistry stubs",
"Molecular and cellular biology stubs"
] |
56,024,347 | https://en.wikipedia.org/wiki/National%20Prize%20for%20Exact%20Sciences%20%28Chile%29 | The National Prize for Exact Sciences () was created in 1992 as one of the replacements for the National Prize for Sciences under Law 19169. The other two prizes in this same area are for Natural Sciences and Applied Sciences and Technologies.
It is part of the National Prize of Chile.
Jury
The jury is made up of the Minister of Education, who calls it, the Rector of the University of Chile, the President of the , a representative of the Council of Rectors, and the last recipient of the prize.
Winners
1981, (physics)
1991, (physics)
1993, and Eric Goles (mathematics)
1995, Claudio Bunster (physics)
1997, María Teresa Ruiz (astronomy)
1999, José Maza Sancho (astronomy)
2001, (physics)
2003, Carlos Conca (mathematics)
2005, (physics)
2007, (physics)
2009, Ricardo Baeza Rodríguez (mathematics)
2011, (mathematics)
2013, Manuel del Pino (mathematics)
2015, Mario Hamuy (astronomy)
2017, (astronomy)
2019, Dora Altbir (nanoscience and nanotechnology)
2021, (astronomy)
2023, Jaime San Martín (mathematics)
See also
CONICYT
List of astronomy awards
List of computer science awards
List of mathematics awards
List of physics awards
References
1992 establishments in Chile
Awards established in 1992
Chilean science and technology awards
Mathematics awards
Physics awards
Astronomy prizes
Computer science awards
Information science awards
1992 in Chilean law | National Prize for Exact Sciences (Chile) | [
"Astronomy",
"Technology"
] | 289 | [
"Astronomy prizes",
"Computer science awards",
"Information science awards",
"Computer science",
"Mathematics awards",
"Science and technology awards",
"Physics awards"
] |
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