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Although there is evidence that habitat loss, hunting, and other factors played a role in the demise of the subfossil lemurs, prior to the synergy hypothesis, each had its own discrepancies. Humans may have hunted the giant lemurs for food, but no signs of game-dependent butchery have been found. Madagascar was coloniz... | Subfossil lemur | Wikipedia | 401 | 27653365 | https://en.wikipedia.org/wiki/Subfossil%20lemur | Biology and health sciences | Strepsirrhini | Animals |
While it is generally agreed that both human and natural factors contributed to the subfossil lemur extinction, studies of sediment cores have helped to clarify the general timeline and initial sequence of events. Spores of the coprophilous fungus, Sporormiella, found in sediment cores experienced a dramatic decline sh... | Subfossil lemur | Wikipedia | 498 | 27653365 | https://en.wikipedia.org/wiki/Subfossil%20lemur | Biology and health sciences | Strepsirrhini | Animals |
By region, studies have revealed specific details that have helped outline the series of events that led to the extinction of the local megafauna. In the Central Highlands, dense forests existed until 1600 CE, with lingering patches persisting until the 19th and 20th centuries. Today, small fragments stand isolated amo... | Subfossil lemur | Wikipedia | 380 | 27653365 | https://en.wikipedia.org/wiki/Subfossil%20lemur | Biology and health sciences | Strepsirrhini | Animals |
Flacourt's 1658 description of the or was the first mention of the now extinct giant lemurs in Western culture, but it is unclear if he saw it. The creature Flacourt described has traditionally been interpreted as a species of Megaladapis. The size may have been exaggerated, and the "round head and a human face" woul... | Subfossil lemur | Wikipedia | 188 | 27653365 | https://en.wikipedia.org/wiki/Subfossil%20lemur | Biology and health sciences | Strepsirrhini | Animals |
In 1995, a research team led by David Burney and Ramilisonina performed interviews in and around Belo sur Mer, including Ambararata and Antsira, to find subfossil megafaunal sites used early in the century by other paleontologists. During carefully controlled interviews, the team recorded stories of recent sightings of... | Subfossil lemur | Wikipedia | 400 | 27653365 | https://en.wikipedia.org/wiki/Subfossil%20lemur | Biology and health sciences | Strepsirrhini | Animals |
Another interviewee, François, a middle-aged woodcutter who spent time in the forests inland (east) from the main road between Morondava and Belo sur Mer, and five of his friends, reported seeing recently. Their description of the animal and François's imitation of its long call were virtually identical to Pascou's. O... | Subfossil lemur | Wikipedia | 394 | 27653365 | https://en.wikipedia.org/wiki/Subfossil%20lemur | Biology and health sciences | Strepsirrhini | Animals |
Although oxygen is the most abundant element in Earth's crust, due to its high reactivity it mostly exists in compound (oxide) forms such as water, carbon dioxide, iron oxides and silicates. Before photosynthesis evolved, Earth's atmosphere had no free diatomic elemental oxygen (O2). Small quantities of oxygen were rel... | Geological history of oxygen | Wikipedia | 468 | 24377796 | https://en.wikipedia.org/wiki/Geological%20history%20of%20oxygen | Physical sciences | Paleoclimate | Earth science |
Early fluctuations in oxygen concentration had little direct effect on life, with mass extinctions not observed until around the start of the Cambrian period, . The presence of provided life with new opportunities. Aerobic metabolism is more efficient than anaerobic pathways, and the presence of oxygen created new pos... | Geological history of oxygen | Wikipedia | 416 | 24377796 | https://en.wikipedia.org/wiki/Geological%20history%20of%20oxygen | Physical sciences | Paleoclimate | Earth science |
The Boring Billion ended during the Neoproterozoic period with a significant increase in photosynthetic activities, causing oxygen levels to rise 10- to 20-fold to about one-tenth of the modern level. This rise in oxygen concentration, known as the Neoproterozoic oxygenation event or "Second Great Oxygenation Event", w... | Geological history of oxygen | Wikipedia | 393 | 24377796 | https://en.wikipedia.org/wiki/Geological%20history%20of%20oxygen | Physical sciences | Paleoclimate | Earth science |
Rising oxygen concentrations have been cited as one of several drivers for evolutionary diversification, although the physiological arguments behind such arguments are questionable, and a consistent pattern between oxygen concentrations and the rate of evolution is not clearly evident. The most celebrated link between ... | Geological history of oxygen | Wikipedia | 344 | 24377796 | https://en.wikipedia.org/wiki/Geological%20history%20of%20oxygen | Physical sciences | Paleoclimate | Earth science |
Cherenkov radiation () is electromagnetic radiation emitted when a charged particle (such as an electron) passes through a dielectric medium (such as distilled water) at a speed greater than the phase velocity (speed of propagation of a wavefront in a medium) of light in that medium. A classic example of Cherenkov rad... | Cherenkov radiation | Wikipedia | 511 | 24383048 | https://en.wikipedia.org/wiki/Cherenkov%20radiation | Physical sciences | Theory of relativity | Physics |
Physical origin
Basics
While the speed of light in vacuum is a universal constant (), the speed in a material may be significantly less, as it is perceived to be slowed by the medium. For example, in water it is only 0.75c. Matter can accelerate to a velocity higher than this (although still less than c, the speed of... | Cherenkov radiation | Wikipedia | 512 | 24383048 | https://en.wikipedia.org/wiki/Cherenkov%20radiation | Physical sciences | Theory of relativity | Physics |
The velocity that must be exceeded is the phase velocity of light rather than the group velocity of light. The phase velocity can be altered dramatically by using a periodic medium, and in that case one can even achieve Cherenkov radiation with no minimum particle velocity, a phenomenon known as the Smith–Purcell effec... | Cherenkov radiation | Wikipedia | 512 | 24383048 | https://en.wikipedia.org/wiki/Cherenkov%20radiation | Physical sciences | Theory of relativity | Physics |
Reverse Cherenkov effect
A reverse Cherenkov effect can be experienced using materials called negative-index metamaterials (materials with a subwavelength microstructure that gives them an effective "average" property very different from their constituent materials, in this case having negative permittivity and negati... | Cherenkov radiation | Wikipedia | 484 | 24383048 | https://en.wikipedia.org/wiki/Cherenkov%20radiation | Physical sciences | Theory of relativity | Physics |
Unlike fluorescence or emission spectra that have characteristic spectral peaks, Cherenkov radiation is continuous. Around the visible spectrum, the relative intensity per unit frequency is approximately proportional to the frequency. That is, higher frequencies (shorter wavelengths) are more intense in Cherenkov radia... | Cherenkov radiation | Wikipedia | 512 | 24383048 | https://en.wikipedia.org/wiki/Cherenkov%20radiation | Physical sciences | Theory of relativity | Physics |
More recently, Cherenkov light has been used to image substances in the body. These discoveries have led to intense interest around the idea of using this light signal to quantify and/or detect radiation in the body, either from internal sources such as injected radiopharmaceuticals or from external beam radiotherapy i... | Cherenkov radiation | Wikipedia | 362 | 24383048 | https://en.wikipedia.org/wiki/Cherenkov%20radiation | Physical sciences | Theory of relativity | Physics |
Astrophysics experiments
When a high-energy (TeV) gamma photon or cosmic ray interacts with the Earth's atmosphere, it may produce an electron–positron pair with enormous velocities. The Cherenkov radiation emitted in the atmosphere by these charged particles is used to determine the direction and energy of the cosmic... | Cherenkov radiation | Wikipedia | 454 | 24383048 | https://en.wikipedia.org/wiki/Cherenkov%20radiation | Physical sciences | Theory of relativity | Physics |
The most advanced type of a detector is the RICH, or ring-imaging Cherenkov detector, developed in the 1980s. In a RICH detector, a cone of Cherenkov light is produced when a high-speed charged particle traverses a suitable medium, often called radiator. This light cone is detected on a position sensitive planar photon... | Cherenkov radiation | Wikipedia | 324 | 24383048 | https://en.wikipedia.org/wiki/Cherenkov%20radiation | Physical sciences | Theory of relativity | Physics |
R136 (formerly known as RMC 136 from the Radcliffe Observatory Magellanic Clouds catalogue) is the central concentration of stars in the NGC 2070 star cluster, which lies at the centre of the Tarantula Nebula in the Large Magellanic Cloud. When originally named it was an unresolved stellar object (catalogued as HD 382... | R136 | Wikipedia | 412 | 6800529 | https://en.wikipedia.org/wiki/R136 | Physical sciences | Notable star clusters | Astronomy |
Components
The cluster contains many of the most massive and luminous stars known, including R136a1. Within the central 5 parsecs there are 32 of the hottest type O stars (O2.0–3.5), 40 other O stars, and 12 Wolf-Rayet stars, mostly of the extremely luminous WNh type. Within 150 parsecs there are a further and 19Wolf-... | R136 | Wikipedia | 194 | 6800529 | https://en.wikipedia.org/wiki/R136 | Physical sciences | Notable star clusters | Astronomy |
The wide-gamut RGB color space (or Adobe Wide Gamut RGB) is a color space developed by Adobe Systems, that offers a large gamut by using pure spectral primary colors.
It is able to store a wider range of color values than sRGB or Adobe RGB color spaces. As a comparison, the wide-gamut RGB color space encompasses 77.6% ... | Wide-gamut RGB color space | Wikipedia | 262 | 915215 | https://en.wikipedia.org/wiki/Wide-gamut%20RGB%20color%20space | Physical sciences | Basics | Physics |
Sheep farming or sheep husbandry is the raising and breeding of domestic sheep. It is a branch of animal husbandry. Sheep are raised principally for their meat (lamb and mutton), milk (sheep's milk), and fiber (wool). They also yield sheepskin and parchment.
Sheep can be raised in a range of temperate climates, includ... | Sheep farming | Wikipedia | 418 | 915258 | https://en.wikipedia.org/wiki/Sheep%20farming | Technology | Animal husbandry | null |
The top producers of sheep meat (average from 1993 to 2013) were as follows: mainland China (1.6 million); Australia (618,000), New Zealand (519,000), the United Kingdom (335,000), and Turkey (288,857). The top five producers of sheep meat in 2013 were mainland China (2 million), Australia (660,000), New Zealand (450,0... | Sheep farming | Wikipedia | 285 | 915258 | https://en.wikipedia.org/wiki/Sheep%20farming | Technology | Animal husbandry | null |
Most lambs are born outdoors. Ewes can be made to give birth in fall, winter, or spring months, either by artificial insemination or by facilitating natural mating. Fall lambing is generally not done as the lamb crop percentage is likely to be low; ewes often need hormone therapy to induce estrus and ovulation, and far... | Sheep farming | Wikipedia | 425 | 915258 | https://en.wikipedia.org/wiki/Sheep%20farming | Technology | Animal husbandry | null |
The Merino breed, accounting for around 80% of the wool produced in Australia, have been selectively bred to have wrinkled skin resulting in excessive amounts of wool while making them much more prone to flystrike. To reduce the risk of flystrike caused by soiling for the lambs who make it to summer, Merino lambs are o... | Sheep farming | Wikipedia | 499 | 915258 | https://en.wikipedia.org/wiki/Sheep%20farming | Technology | Animal husbandry | null |
Saleyards
Sheep sold for slaughter often pass through saleyards, also known as auctions.
Slaughter
When sheep can no longer produce enough wool to be considered profitable, they are sent to slaughter and sold as mutton, and lambs raised for meat are killed between 4 and 12 months of age. Sheep have a natural lifesp... | Sheep farming | Wikipedia | 140 | 915258 | https://en.wikipedia.org/wiki/Sheep%20farming | Technology | Animal husbandry | null |
A tide pool or rock pool is a shallow pool of seawater that forms on the rocky intertidal shore. These pools typically range from a few inches to a few feet deep and a few feet across. Many of these pools exist as separate bodies of water only at low tide, as seawater gets trapped when the tide recedes. Tides are cause... | Tide pool | Wikipedia | 453 | 916571 | https://en.wikipedia.org/wiki/Tide%20pool | Physical sciences | Oceanography | Earth science |
Tide pools exist in the intertidal zone (the area within the tidal range), which is submerged by the sea at high tides and during storms. At other times, the rocks may undergo other extreme conditions, such as baking in the sun or being exposed to cold winds. Few organisms can survive such harsh conditions.
High Tide ... | Tide pool | Wikipedia | 508 | 916571 | https://en.wikipedia.org/wiki/Tide%20pool | Physical sciences | Oceanography | Earth science |
Waves can dislodge mussels and draw them out to sea. Gulls pick up and drop sea urchins to break them open. Sea stars prey on mussels and are eaten by gulls themselves. Black bears are known to sometimes feast on intertidal creatures at low tide. Although tide pool organisms must avoid getting washed away into the ocea... | Tide pool | Wikipedia | 435 | 916571 | https://en.wikipedia.org/wiki/Tide%20pool | Physical sciences | Oceanography | Earth science |
Lichens and barnacles live in the splash zone. Different barnacle species live at very tightly constrained elevations, with tidal conditions precisely determining the exact height of an assemblage relative to sea level. The intertidal zone is periodically exposed to sun and wind, conditions that can cause barnacles to ... | Tide pool | Wikipedia | 190 | 916571 | https://en.wikipedia.org/wiki/Tide%20pool | Physical sciences | Oceanography | Earth science |
Many fish species can live in tidepools. Tidepool fishes are those inhabiting the intertidal zone during part or the entirety of their life cycle, including residents displaying morphological, physiological and behavioral adaptations to withstand the fluctuating environment and non-residents that use the intertidal as ... | Tide pool | Wikipedia | 476 | 916571 | https://en.wikipedia.org/wiki/Tide%20pool | Physical sciences | Oceanography | Earth science |
Recent studies have shown that Postelsia grows in greater numbers when such competition exists; a control group with no competition produced fewer offspring than an experimental group with mussels; from this it is thought that the mussels provide protection for the developing gametophytes. Alternatively, the mussels ma... | Tide pool | Wikipedia | 263 | 916571 | https://en.wikipedia.org/wiki/Tide%20pool | Physical sciences | Oceanography | Earth science |
Nuclear marine propulsion is propulsion of a ship or submarine with heat provided by a nuclear reactor. The power plant heats water to produce steam for a turbine used to turn the ship's propeller through a gearbox or through an electric generator and motor. Nuclear propulsion is used primarily within naval warships su... | Nuclear marine propulsion | Wikipedia | 377 | 916971 | https://en.wikipedia.org/wiki/Nuclear%20marine%20propulsion | Technology | Power generation | null |
In the turbine, the steam expands and reduces its pressure as it imparts energy to the rotating blades of the turbine. There may be many stages of rotating blades and fixed guide vanes. The output shaft of the turbine may be connected to a gearbox to reduce rotation speed, then a shaft connects to the vessel's propel... | Nuclear marine propulsion | Wikipedia | 453 | 916971 | https://en.wikipedia.org/wiki/Nuclear%20marine%20propulsion | Technology | Power generation | null |
As the core of a seagoing reactor is much smaller than a power reactor, the probability of a neutron intersecting with a fissionable nucleus before it escapes into the shielding is much lower. As such, the fuel is typically more highly enriched (i.e., contains a higher concentration of 235U vs. 238U) than that used in ... | Nuclear marine propulsion | Wikipedia | 429 | 916971 | https://en.wikipedia.org/wiki/Nuclear%20marine%20propulsion | Technology | Power generation | null |
Decommissioning
Decommissioning nuclear-powered submarines has become a major task for U.S. and Russian navies. After defuelling, U.S. practice is to cut the reactor section from the vessel for disposal in shallow land burial as low-level waste (see the ship-submarine recycling program). In Russia, whole vessels, or se... | Nuclear marine propulsion | Wikipedia | 467 | 916971 | https://en.wikipedia.org/wiki/Nuclear%20marine%20propulsion | Technology | Power generation | null |
The Soviet Union also developed nuclear submarines. The first types developed were the Project 627, NATO-designated with two water-cooled reactors, the first of which, K-3 Leninsky Komsomol, was underway under nuclear power in 1958.
Nuclear power revolutionized the submarine, finally making it a true "underwater" ves... | Nuclear marine propulsion | Wikipedia | 436 | 916971 | https://en.wikipedia.org/wiki/Nuclear%20marine%20propulsion | Technology | Power generation | null |
The French carrier is equipped with catapults and arresters. The has 42,000 tonnes, is the flagship of the French Navy (Marine Nationale). The ship carries a complement of Dassault Rafale M and E‑2C Hawkeye aircraft, EC725 Caracal and AS532 Cougar helicopters for combat search and rescue, as well as modern electronic... | Nuclear marine propulsion | Wikipedia | 480 | 916971 | https://en.wikipedia.org/wiki/Nuclear%20marine%20propulsion | Technology | Power generation | null |
The last nuclear-powered cruisers the Americans would produce would be the four-ship . was commissioned in 1976, followed by in 1977, in 1978 and finally in 1980. Ultimately, all these ships proved to be too costly to maintain and they were all retired between 1993 and 1999.
Other military ships
Communication and... | Nuclear marine propulsion | Wikipedia | 351 | 916971 | https://en.wikipedia.org/wiki/Nuclear%20marine%20propulsion | Technology | Power generation | null |
Merchant ships
Nuclear-powered civil merchant ships have not developed beyond a few experimental ships. The U.S.-built , completed in 1962, was primarily a demonstration of civil nuclear power and was too small and expensive to operate economically as a merchant ship. The design was too much of a compromise, being neit... | Nuclear marine propulsion | Wikipedia | 252 | 916971 | https://en.wikipedia.org/wiki/Nuclear%20marine%20propulsion | Technology | Power generation | null |
Despite this, there is still interest in nuclear propulsion. In November 2010 British Maritime Technology and Lloyd's Register embarked upon a two-year study with U.S.-based Hyperion Power Generation (now Gen4 Energy), and the Greek ship operator Enterprises Shipping and Trading SA to investigate the practical maritime... | Nuclear marine propulsion | Wikipedia | 451 | 916971 | https://en.wikipedia.org/wiki/Nuclear%20marine%20propulsion | Technology | Power generation | null |
Merchant cargo ships
USNS American Explorer; United States tanker, converted to conventional power while under construction
, Japan (1970–1992); never carried commercial cargo, rebuilt as diesel engine powered RV Mirai in 1996
, Germany (1968–1979); re-powered with diesel engine in 1979
, United States (1962–1972)
... | Nuclear marine propulsion | Wikipedia | 480 | 916971 | https://en.wikipedia.org/wiki/Nuclear%20marine%20propulsion | Technology | Power generation | null |
Potassium alum, potash alum, or potassium aluminium sulfate is a chemical compound first mentioned under various Sanskrit names in Ayurvedic medicinal texts such as , , and ; is chemically defined as the double sulfate of potassium and aluminium, with chemical formula KAl(SO4)2. It is commonly encountered as the dodec... | Potassium alum | Wikipedia | 489 | 917400 | https://en.wikipedia.org/wiki/Potassium%20alum | Physical sciences | Sulfuric oxyanions | Chemistry |
According to Levey, potassium alum was used in "classical times" as a flux when soldering copper, in the fireproofing of wood, and in the separation of silver and gold, but that there is no evidence that these uses existed in Mesopotamia.
Greece
The production of potassium alum from alunite is archaeologically attest... | Potassium alum | Wikipedia | 410 | 917400 | https://en.wikipedia.org/wiki/Potassium%20alum | Physical sciences | Sulfuric oxyanions | Chemistry |
England
Potassium alum was imported into England mainly from the Middle East, and, from the late 15th century onwards, the Papal States for hundreds of years. Its use there was as a dye-fixer (mordant) for wool (which was one of England's primary industries, the value of which increased significantly if dyed). These s... | Potassium alum | Wikipedia | 498 | 917400 | https://en.wikipedia.org/wiki/Potassium%20alum | Physical sciences | Sulfuric oxyanions | Chemistry |
Louis Vauquelin then conjectured that potassium was likewise an ingredient in many other minerals. Given Marggraf and Bergman's experiments, he suspected that this alkali constituted an essential ingredient of natural alum. In 1797 he published a dissertation demonstrating that alum is a double salt, composed of sulfu... | Potassium alum | Wikipedia | 469 | 917400 | https://en.wikipedia.org/wiki/Potassium%20alum | Physical sciences | Sulfuric oxyanions | Chemistry |
Potassium alum is now produced industrially by adding potassium sulfate to a concentrated solution of aluminium sulfate. The aluminium sulfate is usually obtained by treating minerals like alum schist, bauxite and cryolite with sulfuric acid. If much iron should be present in the sulfate then it is preferable to use ... | Potassium alum | Wikipedia | 351 | 917400 | https://en.wikipedia.org/wiki/Potassium%20alum | Physical sciences | Sulfuric oxyanions | Chemistry |
Potassium and ammonium alum are the active ingredients in some antiperspirants and deodorants, acting by inhibiting the growth of the bacteria responsible for body odor. Alum's antiperspirant and antibacterial properties contribute to its traditional use as an underarm deodorant. It has been used for this purpose in E... | Potassium alum | Wikipedia | 476 | 917400 | https://en.wikipedia.org/wiki/Potassium%20alum | Physical sciences | Sulfuric oxyanions | Chemistry |
Tanning
Potassium alum is used in leather tanning, in order to remove moisture from the hide and prevent rotting. Unlike tannic acid, alum doesn't bind to the hide and can be washed out of it.
Dyeing
Alum has been used since antiquity as mordant to form a permanent bond between dye and natural textile fibers like woo... | Potassium alum | Wikipedia | 504 | 917400 | https://en.wikipedia.org/wiki/Potassium%20alum | Physical sciences | Sulfuric oxyanions | Chemistry |
A washer is a thin plate (typically disk-shaped, but sometimes square) with a hole (typically in the middle) that is normally used to distribute the load of a threaded fastener, such as a bolt or nut. Other uses are as a spacer, spring (Belleville washer, wave washer), wear pad, preload indicating device, locking devic... | Washer (hardware) | Wikipedia | 484 | 918643 | https://en.wikipedia.org/wiki/Washer%20%28hardware%29 | Technology | Rigid components | null |
The DIN 125 metric washer standard refers to subtypes A and B. ISO 7089 calls these Form A and ISO 7090 calls them Form B. They are all the same overall size, but Form B is chamfered on one side.
Materials
Washers can be fabricated from a variety of materials including, but not limited to:
Steel – Carbon steel, sprin... | Washer (hardware) | Wikipedia | 299 | 918643 | https://en.wikipedia.org/wiki/Washer%20%28hardware%29 | Technology | Rigid components | null |
Corrosion resistance
A number of techniques are used to enhance the corrosion resistant properties of certain washer materials:
Metallic coatings – Typical coatings used to produce corrosion resistant washers are zinc, cadmium, and nickel. Zinc coating acts as a sacrificial surface layer that falls victim to corrosiv... | Washer (hardware) | Wikipedia | 351 | 918643 | https://en.wikipedia.org/wiki/Washer%20%28hardware%29 | Technology | Rigid components | null |
"Type" is not to be confused with "form" (but often is). The British Standard for Metric Series Metal Washers (BS4320), written in 1968, coined the term "form". The forms go from A to G and dictate the outside diameter and thickness of the flat washers.
Form A: Normal diameter, normal thickness
Form B: Normal diamete... | Washer (hardware) | Wikipedia | 382 | 918643 | https://en.wikipedia.org/wiki/Washer%20%28hardware%29 | Technology | Rigid components | null |
In Electrical Engineering, the process of circuit design can cover systems ranging from complex electronic systems down to the individual transistors within an integrated circuit. One person can often do the design process without needing a planned or structured design process for simple circuits. Still, teams of desi... | Circuit design | Wikipedia | 471 | 2848344 | https://en.wikipedia.org/wiki/Circuit%20design | Technology | Basics_4 | null |
As the design process progresses, the designer(s) will frequently return to the specification and alter it to take account of the progress of the design. This can involve tightening specifications that the customer has supplied and adding tests that the circuit must pass to be accepted. These additional specifications... | Circuit design | Wikipedia | 499 | 2848344 | https://en.wikipedia.org/wiki/Circuit%20design | Technology | Basics_4 | null |
Finally, the individual circuit components are chosen to carry out each function in the overall design; at this stage, the physical layout and electrical connections of each component are also decided, this layout commonly taking the form of artwork for the production of a printed circuit board or Integrated circuit. ... | Circuit design | Wikipedia | 419 | 2848344 | https://en.wikipedia.org/wiki/Circuit%20design | Technology | Basics_4 | null |
Verification and testing
Once a circuit has been designed, it must be both verified and tested. Verification is the process of going through each stage of a design and ensuring that it will do what the specification requires it to do. This is frequently a highly mathematical process and can involve large-scale compute... | Circuit design | Wikipedia | 446 | 2848344 | https://en.wikipedia.org/wiki/Circuit%20design | Technology | Basics_4 | null |
Results
Every electrical circuit starts with a circuit board simulator of how the things will be put together at the end of the day and show how the circuit will work virtually. A blueprint is the drawing of the technical design and final product. After all, this is done, and you use the blueprint to put the circuit t... | Circuit design | Wikipedia | 245 | 2848344 | https://en.wikipedia.org/wiki/Circuit%20design | Technology | Basics_4 | null |
A cosmological horizon is a measure of the distance from which one could possibly retrieve information. This observable constraint is due to various properties of general relativity, the expanding universe, and the physics of Big Bang cosmology. Cosmological horizons set the size and scale of the observable universe. T... | Cosmological horizon | Wikipedia | 462 | 2848730 | https://en.wikipedia.org/wiki/Cosmological%20horizon | Physical sciences | Physical cosmology | Astronomy |
It is a common misconception that light from the Hubble radius can never reach us. In models assuming decreasing with time (some cases of Friedmann universe), while particles on the Hubble radius recede from us with the speed of light, the Hubble radius gets larger over time, so light emitted towards us from a particl... | Cosmological horizon | Wikipedia | 475 | 2848730 | https://en.wikipedia.org/wiki/Cosmological%20horizon | Physical sciences | Physical cosmology | Astronomy |
Future horizon
In an accelerating universe, there are events which will be unobservable as as signals from future events become redshifted to arbitrarily long wavelengths in the exponentially expanding de Sitter space. This sets a limit on the farthest distance that we can possibly see as measured in units of proper d... | Cosmological horizon | Wikipedia | 362 | 2848730 | https://en.wikipedia.org/wiki/Cosmological%20horizon | Physical sciences | Physical cosmology | Astronomy |
Oppositional defiant disorder (ODD) is listed in the DSM-5 under Disruptive, impulse-control, and conduct disorders and defined as "a pattern of angry/irritable mood, argumentative/defiant behavior, or vindictiveness." This behavior is usually targeted toward peers, parents, teachers, and other authority figures, incl... | Oppositional defiant disorder | Wikipedia | 424 | 2849297 | https://en.wikipedia.org/wiki/Oppositional%20defiant%20disorder | Biology and health sciences | Mental disorders | Health |
There is a difference in prevalence between boys and girls, with a ratio of 1.4 to 1 before adolescence. Other research suggests a 2:1 ratio. Prevalence in girls tends to increase after puberty. Researchers have found that the general prevalence of ODD throughout cultures remains constant. However, the gendered dispari... | Oppositional defiant disorder | Wikipedia | 390 | 2849297 | https://en.wikipedia.org/wiki/Oppositional%20defiant%20disorder | Biology and health sciences | Mental disorders | Health |
Earlier conceptions of ODD had higher rates of diagnosis. When the disorder was first included in the DSM-III, the prevalence was 25% higher than when the DSM-IV revised the criteria of diagnosis. The DSM-V made more changes to the criteria, grouping certain characteristics together in order to demonstrate that people ... | Oppositional defiant disorder | Wikipedia | 488 | 2849297 | https://en.wikipedia.org/wiki/Oppositional%20defiant%20disorder | Biology and health sciences | Mental disorders | Health |
Etiology
There is no specific element that has yet been identified as directly causing ODD. Research looking precisely at the etiological factors linked with ODD is limited. The literature often examines common risk factors linked with all disruptive behaviors, rather than ODD specifically. Symptoms of ODD are also oft... | Oppositional defiant disorder | Wikipedia | 488 | 2849297 | https://en.wikipedia.org/wiki/Oppositional%20defiant%20disorder | Biology and health sciences | Mental disorders | Health |
Neurobiological factors
Deficits and injuries to certain areas of the brain can lead to serious behavioral problems in children. Brain imaging studies have suggested that children with ODD may have hypofunction in the part of the brain responsible for reasoning, judgment, and impulse control. Children with ODD are thou... | Oppositional defiant disorder | Wikipedia | 468 | 2849297 | https://en.wikipedia.org/wiki/Oppositional%20defiant%20disorder | Biology and health sciences | Mental disorders | Health |
Negative parenting practices and parent–child conflict may lead to antisocial behavior, but they may also be a reaction to the oppositional and aggressive behaviors of children. Factors such as a family history of mental illnesses and/or substance use disorders as well as a dysfunctional family and inconsistent discipl... | Oppositional defiant disorder | Wikipedia | 466 | 2849297 | https://en.wikipedia.org/wiki/Oppositional%20defiant%20disorder | Biology and health sciences | Mental disorders | Health |
For a child or adolescent to qualify for a diagnosis of ODD, behaviors must cause considerable distress for the family or interfere significantly with academic or social functioning. Such interference might manifest as challenges in learning at school, making friends, or placing the individual in harmful situations. Th... | Oppositional defiant disorder | Wikipedia | 425 | 2849297 | https://en.wikipedia.org/wiki/Oppositional%20defiant%20disorder | Biology and health sciences | Mental disorders | Health |
Psychopharmacological treatment is the use of prescribed medication in managing oppositional defiant disorder. Prescribed medications to control ODD include mood stabilizers, anti-psychotics, and stimulants. In two controlled randomized trials, it was found that between administered lithium and the placebo group, admin... | Oppositional defiant disorder | Wikipedia | 507 | 2849297 | https://en.wikipedia.org/wiki/Oppositional%20defiant%20disorder | Biology and health sciences | Mental disorders | Health |
Multimodal intervention
Multimodal intervention is an effective treatment that looks at different levels including family, peers, school, and neighborhood. It is an intervention that concentrates on multiple risk factors. The focus is on parent training, classroom social skills, and playground behavior programs. The i... | Oppositional defiant disorder | Wikipedia | 380 | 2849297 | https://en.wikipedia.org/wiki/Oppositional%20defiant%20disorder | Biology and health sciences | Mental disorders | Health |
Oppositional defiant disorder's validity as a diagnosis has been criticized since its inclusion in the DSM III in 1980. ODD was considered to produce minor impairment insufficient to qualify as a medical diagnosis, and was difficult to separate from conduct disorder, with some estimates that over 50% of those diagnose... | Oppositional defiant disorder | Wikipedia | 281 | 2849297 | https://en.wikipedia.org/wiki/Oppositional%20defiant%20disorder | Biology and health sciences | Mental disorders | Health |
Research has shown that African Americans and Latino Americans are disproportionately likely to be diagnosed with ODD compared to White counterparts displaying the same symptoms, who are more likely to be diagnosed with ADHD. Assessment, diagnosis and treatment of ODD may not account for contextual problems experienced... | Oppositional defiant disorder | Wikipedia | 402 | 2849297 | https://en.wikipedia.org/wiki/Oppositional%20defiant%20disorder | Biology and health sciences | Mental disorders | Health |
Absolute dating is the process of determining an age on a specified chronology in archaeology and geology. Some scientists prefer the terms chronometric or calendar dating, as use of the word "absolute" implies an unwarranted certainty of accuracy. Absolute dating provides a numerical age or range, in contrast with re... | Absolute dating | Wikipedia | 497 | 2851214 | https://en.wikipedia.org/wiki/Absolute%20dating | Physical sciences | Geochronology | Earth science |
It takes 5,730 years for half the carbon-14 to decay to nitrogen; this is the half-life of carbon-14. After another 5,730 years, only one-quarter of the original carbon-14 will remain. After yet another 5,730 years, only one-eighth will be left.
By measuring the carbon-14 in organic material, scientists can determine... | Absolute dating | Wikipedia | 489 | 2851214 | https://en.wikipedia.org/wiki/Absolute%20dating | Physical sciences | Geochronology | Earth science |
Thermoluminescence
Thermoluminescence testing also dates items to the last time they were heated. This technique is based on the principle that all objects absorb radiation from the environment. This process frees electrons within minerals that remain caught within the item.
Heating an item to 500 degrees Celsius or... | Absolute dating | Wikipedia | 501 | 2851214 | https://en.wikipedia.org/wiki/Absolute%20dating | Physical sciences | Geochronology | Earth science |
In some areas of the world, it is possible to date wood back a few thousand years, or even many thousands. Currently, the maximum for fully anchored chronologies is a little over 11,000 years from present.
Amino acid dating
Amino acid dating is a dating technique used to estimate the age of a specimen in paleobiolog... | Absolute dating | Wikipedia | 247 | 2851214 | https://en.wikipedia.org/wiki/Absolute%20dating | Physical sciences | Geochronology | Earth science |
In orbital mechanics, a frozen orbit is an orbit for an artificial satellite in which perturbations have been minimized by careful selection of the orbital parameters. Perturbations can result from natural drifting due to the central body's shape, or other factors. Typically, the altitude of a satellite in a frozen orb... | Frozen orbit | Wikipedia | 508 | 31516478 | https://en.wikipedia.org/wiki/Frozen%20orbit | Physical sciences | Orbital mechanics | Astronomy |
The perturbing force caused by the oblateness of the Earth will in general perturb not only the orbital plane but also the eccentricity vector of the orbit. There exists, however, an almost circular orbit for which there are no secular/long periodic perturbations of the eccentricity vector, only periodic perturbations ... | Frozen orbit | Wikipedia | 508 | 31516478 | https://en.wikipedia.org/wiki/Frozen%20orbit | Physical sciences | Orbital mechanics | Astronomy |
This analysis can be carried out as follows:
In the article orbital perturbation analysis the secular perturbation of the orbital pole from the term of the geopotential model is shown to be
which can be expressed in terms of orbital elements thus:
Making a similar analysis for the term (corresponding to the fact ... | Frozen orbit | Wikipedia | 474 | 31516478 | https://en.wikipedia.org/wiki/Frozen%20orbit | Physical sciences | Orbital mechanics | Astronomy |
For this the analytical expression () is used to iteratively update the initial (mean) eccentricity vector to obtain that the (mean) eccentricity vector several orbits later computed by the precise numerical propagation takes precisely the same value. In this way the secular perturbation of the eccentricity vector caus... | Frozen orbit | Wikipedia | 484 | 31516478 | https://en.wikipedia.org/wiki/Frozen%20orbit | Physical sciences | Orbital mechanics | Astronomy |
To be able to apply relations derived in the article Orbital perturbation analysis (spacecraft) the force component must be split into two orthogonal components and as illustrated in figure 2
Let make up a rectangular coordinate system with origin in the center of the Earth (in the center of the Reference ellipsoi... | Frozen orbit | Wikipedia | 478 | 31516478 | https://en.wikipedia.org/wiki/Frozen%20orbit | Physical sciences | Orbital mechanics | Astronomy |
Yttrium is a chemical element; it has symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost always found in combination with lanthanide elements in rare-earth minerals and is never found i... | Yttrium | Wikipedia | 507 | 20373503 | https://en.wikipedia.org/wiki/Yttrium | Physical sciences | Chemical elements_2 | null |
Similarity to the lanthanides
The similarities of yttrium to the lanthanides are so strong that the element has been grouped with them as a rare-earth element, and is always found in nature together with them in rare-earth minerals. Chemically, yttrium resembles those elements more closely than its neighbor in the per... | Yttrium | Wikipedia | 463 | 20373503 | https://en.wikipedia.org/wiki/Yttrium | Physical sciences | Chemical elements_2 | null |
With halogens, yttrium forms trihalides such as yttrium(III) fluoride (), yttrium(III) chloride (), and yttrium(III) bromide () at temperatures above roughly 200 °C. Similarly, carbon, phosphorus, selenium, silicon and sulfur all form binary compounds with yttrium at elevated temperatures.
Organoyttrium chemistry is t... | Yttrium | Wikipedia | 508 | 20373503 | https://en.wikipedia.org/wiki/Yttrium | Physical sciences | Chemical elements_2 | null |
All group 3 elements have an odd atomic number, and therefore few stable isotopes. Scandium has one stable isotope, and yttrium itself has only one stable isotope, Y, which is also the only isotope that occurs naturally. However, the lanthanide rare earths contain elements of even atomic number and many stable isotopes... | Yttrium | Wikipedia | 510 | 20373503 | https://en.wikipedia.org/wiki/Yttrium | Physical sciences | Chemical elements_2 | null |
History
In 1787, part-time chemist Carl Axel Arrhenius found a heavy black rock in an old quarry near the Swedish village of Ytterby (now part of the Stockholm Archipelago). Thinking it was an unknown mineral containing the newly discovered element tungsten, he named it ytterbite and sent samples to various chemists fo... | Yttrium | Wikipedia | 511 | 20373503 | https://en.wikipedia.org/wiki/Yttrium | Physical sciences | Chemical elements_2 | null |
Abundance
Yttrium is found in most rare-earth minerals, and some uranium ores, but never in the Earth's crust as a free element. About 31 ppm of the Earth's crust is yttrium, making it the 43rd most abundant element. Yttrium is found in soil in concentrations between 10 and 150 ppm (dry weight average of 23 ppm) and in... | Yttrium | Wikipedia | 475 | 20373503 | https://en.wikipedia.org/wiki/Yttrium | Physical sciences | Chemical elements_2 | null |
Rare-earth elements (REEs) come mainly from four sources:
Carbonate and fluoride containing ores such as the LREE bastnäsite ((Ce, La, etc.)(CO)F) contain on average 0.1% yttrium compared to the 99.9% for the 16 other REEs. The main source of bastnäsite from the 1960s to the 1990s was the Mountain Pass rare earth mine... | Yttrium | Wikipedia | 421 | 20373503 | https://en.wikipedia.org/wiki/Yttrium | Physical sciences | Chemical elements_2 | null |
One method for obtaining pure yttrium from the mixed oxide ores is to dissolve the oxide in sulfuric acid and fractionate it by ion exchange chromatography. With the addition of oxalic acid, the yttrium oxalate precipitates. The oxalate is converted into the oxide by heating under oxygen. By reacting the resulting yttr... | Yttrium | Wikipedia | 502 | 20373503 | https://en.wikipedia.org/wiki/Yttrium | Physical sciences | Chemical elements_2 | null |
Yttrium compounds are used as a catalyst for ethylene polymerization. As a metal, yttrium is used on the electrodes of some high-performance spark plugs. Yttrium is used in gas mantles for propane lanterns as a replacement for thorium, which is radioactive.
Garnets
Yttrium is used in the production of a large variety... | Yttrium | Wikipedia | 483 | 20373503 | https://en.wikipedia.org/wiki/Yttrium | Physical sciences | Chemical elements_2 | null |
Yttrium has been studied as a nodulizer in ductile cast iron, forming the graphite into compact nodules instead of flakes to increase ductility and fatigue resistance. Having a high melting point, yttrium oxide is used in some ceramic and glass to impart shock resistance and low thermal expansion properties. Those same... | Yttrium | Wikipedia | 459 | 20373503 | https://en.wikipedia.org/wiki/Yttrium | Physical sciences | Chemical elements_2 | null |
Yttrium is a key ingredient in the yttrium barium copper oxide (YBaCuO, aka 'YBCO' or '1-2-3') superconductor developed at the University of Alabama in Huntsville and the University of Houston in 1987. This superconductor is notable because the operating superconductivity temperature is above liquid nitrogen's boiling ... | Yttrium | Wikipedia | 356 | 20373503 | https://en.wikipedia.org/wiki/Yttrium | Physical sciences | Chemical elements_2 | null |
Lithium batteries
Yttrium is used in small quantities in the cathodes of some Lithium iron phosphate battery (LFP), which are then commonly called LiFeYPO chemistry, or LYP. Similar to LFP, LYP batteries offer high energy density, good safety and long life. But LYP offers higher cathode stability, and prolongs the life... | Yttrium | Wikipedia | 368 | 20373503 | https://en.wikipedia.org/wiki/Yttrium | Physical sciences | Chemical elements_2 | null |
Exposure to yttrium compounds in humans may cause lung disease. Workers exposed to airborne yttrium europium vanadate dust experienced mild eye, skin, and upper respiratory tract irritation—though this may be caused by the vanadium content rather than the yttrium. Acute exposure to yttrium compounds can cause shortness... | Yttrium | Wikipedia | 162 | 20373503 | https://en.wikipedia.org/wiki/Yttrium | Physical sciences | Chemical elements_2 | null |
Megalictis (meaning "great weasel") is an extinct genus of large predatory mustelids that existed in North America during the "cat gap" from the Late Arikareean (Ar4) in the Miocene epoch. It is thought to have resembled a huge, jaguar-sized ferret, weighing up to .
History of discovery
The genus Megalictis was first ... | Megalictis | Wikipedia | 437 | 20381199 | https://en.wikipedia.org/wiki/Megalictis | Biology and health sciences | Mustelidae | Animals |
Description
Megalictis was one of the largest terrestrial mustelids ever recorded, surpassing in size other mustelids like Ekorus, Eomellivora, and Plesiogulo. Recovered skulls of Megalictis ferox had similar condylobasal lengths to small modern jaguars, ranging from in length, and were almost as wide in mastoid wi... | Megalictis | Wikipedia | 267 | 20381199 | https://en.wikipedia.org/wiki/Megalictis | Biology and health sciences | Mustelidae | Animals |
Environmental resource management or environmental management is the management of the interaction and impact of human societies on the environment. It is not, as the phrase might suggest, the management of the environment itself. Environmental resources management aims to ensure that ecosystem services are protected a... | Environmental resource management | Wikipedia | 414 | 1407416 | https://en.wikipedia.org/wiki/Environmental%20resource%20management | Physical sciences | Earth science basics: General | Earth science |
Ethical
Environmental resource management strategies are intrinsically driven by conceptions of human-nature relationships. Ethical aspects involve the cultural and social issues relating to the environment, and dealing with changes to it. "All human activities take place in the context of certain types of relationship... | Environmental resource management | Wikipedia | 448 | 1407416 | https://en.wikipedia.org/wiki/Environmental%20resource%20management | Physical sciences | Earth science basics: General | Earth science |
Economics
Main article: Economics
The economy functions within and is dependent upon goods and services provided by natural ecosystems. The role of the environment is recognized in both classical economics and neoclassical economics theories, yet the environment was a lower priority in economic policies from 1950 to 19... | Environmental resource management | Wikipedia | 496 | 1407416 | https://en.wikipedia.org/wiki/Environmental%20resource%20management | Physical sciences | Earth science basics: General | Earth science |
A common scientific concept and impetus behind environmental resource management is carrying capacity. Simply put, carrying capacity refers to the maximum number of organisms a particular resource can sustain. The concept of carrying capacity, whilst understood by many cultures over history, has its roots in Malthusian... | Environmental resource management | Wikipedia | 458 | 1407416 | https://en.wikipedia.org/wiki/Environmental%20resource%20management | Physical sciences | Earth science basics: General | Earth science |
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