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The cup is a cooking measure of volume, commonly associated with cooking and serving sizes. In the US, it is traditionally equal to . Because actual drinking cups may differ greatly from the size of this unit, standard measuring cups may be used, with a metric cup commonly being rounded up to 240 millilitres (legal cup... | Cup (unit) | Wikipedia | 415 | 2968115 | https://en.wikipedia.org/wiki/Cup%20%28unit%29 | Physical sciences | Volume | Basics and measurement |
A "coffee cup" is 1.5 dL (i.e. 150 millilitres or 5.07 US customary fluid ounces), and is occasionally used in recipes; in older recipes, cup may mean "coffee cup". It is also used in the US to specify coffeemaker sizes (what can be referred to as a Tasse à café). A "12-cup" US coffeemaker makes 57.6 US customary fluid... | Cup (unit) | Wikipedia | 385 | 2968115 | https://en.wikipedia.org/wiki/Cup%20%28unit%29 | Physical sciences | Volume | Basics and measurement |
All six units are the traditional British equivalents of the US customary cup and the metric cup, used in situations where a US cook would use the US customary cup and a cook using metric units the metric cup. The breakfast cup is the most similar in size to the US customary cup and the metric cup. Which of these six... | Cup (unit) | Wikipedia | 473 | 2968115 | https://en.wikipedia.org/wiki/Cup%20%28unit%29 | Physical sciences | Volume | Basics and measurement |
Russian cup
The traditional Russian measurement system included two cup sizes: the "charka" (cup proper) and the "stakan" ("glass"). The charka was usually used for alcoholic drinks and is 123mL (about 4·33 British imperial fluid ounces or 4·16 US customary fluid ounces), while the stakan, used for other liquids, was ... | Cup (unit) | Wikipedia | 406 | 2968115 | https://en.wikipedia.org/wiki/Cup%20%28unit%29 | Physical sciences | Volume | Basics and measurement |
Thrinaxodon is an extinct genus of cynodonts, including the species T. liorhinus which lived in what are now South Africa and Antarctica during the Late Permian - Early Triassic. Thrinaxodon lived just after the Permian–Triassic mass extinction event, its survival during the extinction may have been due to its burrowin... | Thrinaxodon | Wikipedia | 426 | 2969781 | https://en.wikipedia.org/wiki/Thrinaxodon | Biology and health sciences | Proto-mammals | Animals |
On the skull roof of Thrinaxodon, the fronto-nasal suture represents an arrow shape instead of the general transverse process seen in more primitive skull morphologies. The prefrontals, which are slightly anterior and ventral to the frontals exhibit a very small size and come in contact with the post-orbitals, frontals... | Thrinaxodon | Wikipedia | 393 | 2969781 | https://en.wikipedia.org/wiki/Thrinaxodon | Biology and health sciences | Proto-mammals | Animals |
The otic region is defined by the regions surrounding the temporal fenestrae. Most notable is evidence of a deep recess that is just anterior to the fenestra ovalis, containing evidence of smooth muscle interactions with the skull. Such smooth muscle interactions have been interpreted to be indicative of the tympanum a... | Thrinaxodon | Wikipedia | 480 | 2969781 | https://en.wikipedia.org/wiki/Thrinaxodon | Biology and health sciences | Proto-mammals | Animals |
Upper incisors in T. liorhinus assume a backwards directed cusp, being curved and pointed at their most distal point, and becoming broader and rounder as they reach their proximal insertion point into the premaxilla. The fourth upper incisor is roughly homologous with a small canine tooth in form, but is positioned too... | Thrinaxodon | Wikipedia | 312 | 2969781 | https://en.wikipedia.org/wiki/Thrinaxodon | Biology and health sciences | Proto-mammals | Animals |
The upper and lower postcanines in T. liorhinus share some common features but also vary quite a fair amount in comparison to one another. The first postcanine (just posterior to the canine) is most often smaller than the other postcanines and is most often bicuspid. Including the first postcanine, if any of the other ... | Thrinaxodon | Wikipedia | 489 | 2969781 | https://en.wikipedia.org/wiki/Thrinaxodon | Biology and health sciences | Proto-mammals | Animals |
The bone tissue of Thrinaxodon consists of fibro-lamellar bone, to a varying degree across all the separate limbs, most of which develops into parallel-fibred bone tissue towards the periphery. Each of the bones contains a large abundance of globular osteocyte lacunae which radiate a multitude of branched canaliculi. O... | Thrinaxodon | Wikipedia | 273 | 2969781 | https://en.wikipedia.org/wiki/Thrinaxodon | Biology and health sciences | Proto-mammals | Animals |
Within the femur of Thrinaxodon, there is no major region of the bone that is made of parallel-fibred tissues; however, there is a small ring of parallel-fibred bone within the mid-cortex. The remainder of the femur is made of fibro-lamellar tissue; however, the globular osteocyte lacunae become much more organized and... | Thrinaxodon | Wikipedia | 432 | 2969781 | https://en.wikipedia.org/wiki/Thrinaxodon | Biology and health sciences | Proto-mammals | Animals |
Thrinaxodon was initially believed to be isolated to that region. Other fossils in South Africa were recovered from the Normandien and Katberg Formations. It had not been until 1977 that additional fossils of Thrinaxodon had been discovered in the Fremouw Formation of Antarctica. Upon its discovery there, numerous exp... | Thrinaxodon | Wikipedia | 387 | 2969781 | https://en.wikipedia.org/wiki/Thrinaxodon | Biology and health sciences | Proto-mammals | Animals |
Classification
Thrinaxodon belongs to the clade Epicynodontia, a subdivision of the greater clade Cynodontia. Cynodontia eventually led to the evolution of Morganucodon and all other mammalia. Cynodontia belongs to the clade Therapsida, which was the first major clade along the line of the Synapsida. Synapsida repre... | Thrinaxodon | Wikipedia | 329 | 2969781 | https://en.wikipedia.org/wiki/Thrinaxodon | Biology and health sciences | Proto-mammals | Animals |
Posture
The posture of Thrinaxodon is an interesting subject, because it represents a transition between the sprawling behavior of the more lizard-like pelycosaurs and the more upright behavior found in modern, and many extinct, Mammalia. In cynodonts such as Thrinaxodon, the distal femoral condyle articulates with th... | Thrinaxodon | Wikipedia | 475 | 2969781 | https://en.wikipedia.org/wiki/Thrinaxodon | Biology and health sciences | Proto-mammals | Animals |
The earliest discovery of a burrowing Thrinaxodon places the specimen found around 251 million years ago, a time frame surrounding the Permian–Triassic extinction event. Much of these fossils had been found in the flood plains of South Africa, in the Karoo Basin. This behavior had been seen at a relatively low occurren... | Thrinaxodon | Wikipedia | 278 | 2969781 | https://en.wikipedia.org/wiki/Thrinaxodon | Biology and health sciences | Proto-mammals | Animals |
A Thrinaxodon burrow contained an injured temnospondyl, Broomistega. The burrow was scanned using a synchrotron, a tool used to observe the contents of the burrows in this experiment, and not damage the intact specimens. The synchrotron revealed an injured rhinesuchid, Broomistega putterilli, showing signs of broken or... | Thrinaxodon | Wikipedia | 253 | 2969781 | https://en.wikipedia.org/wiki/Thrinaxodon | Biology and health sciences | Proto-mammals | Animals |
Gnetum gnemon is a gymnosperm species of Gnetum, its native area spans from Mizoram and Assam in India down south through Malay Peninsula, Malay Archipelago and the Philippines in southeast Asia to the western Pacific islands. Common names include gnetum, joint fir, two leaf, melinjo/belinjo (Indonesian), bago (Filipin... | Gnetum gnemon | Wikipedia | 512 | 1500225 | https://en.wikipedia.org/wiki/Gnetum%20gnemon | Biology and health sciences | Gymnosperms (except conifers) | Plants |
Gnetum is most widely used in Indonesian cuisine where it is known as melinjo or belinjo. The seeds are used for sayur asem (sour vegetable soup) and also, made into raw chips that later need to be deep-fried as crackers (emping, a type of krupuk). The crackers have a slightly bitter taste and are frequently served a... | Gnetum gnemon | Wikipedia | 417 | 1500225 | https://en.wikipedia.org/wiki/Gnetum%20gnemon | Biology and health sciences | Gymnosperms (except conifers) | Plants |
The separation of a 50% ethanol extract of the dried endosperms yielded gnetin C, gnetin L (new stilbenoid), gnemonosides A, C and D, and resveratrol which were tested for DPPH radical scavenging action, antimicrobial activity and inhibition of lipase and α-amylase from porcine pancreas. Gnetin C showed the best effect... | Gnetum gnemon | Wikipedia | 257 | 1500225 | https://en.wikipedia.org/wiki/Gnetum%20gnemon | Biology and health sciences | Gymnosperms (except conifers) | Plants |
In statistics, the coefficient of determination, denoted R2 or r2 and pronounced "R squared", is the proportion of the variation in the dependent variable that is predictable from the independent variable(s).
It is a statistic used in the context of statistical models whose main purpose is either the prediction of fut... | Coefficient of determination | Wikipedia | 399 | 1500869 | https://en.wikipedia.org/wiki/Coefficient%20of%20determination | Mathematics | Probability | null |
When evaluating the goodness-of-fit of simulated (Ypred) versus measured (Yobs) values, it is not appropriate to base this on the R2 of the linear regression (i.e., Yobs= m·Ypred + b). The R2 quantifies the degree of any linear correlation between Yobs and Ypred, while for the goodness-of-fit evaluation only one specif... | Coefficient of determination | Wikipedia | 478 | 1500869 | https://en.wikipedia.org/wiki/Coefficient%20of%20determination | Mathematics | Probability | null |
See Partitioning in the general OLS model for a derivation of this result for one case where the relation holds. When this relation does hold, the above definition of R2 is equivalent to
where n is the number of observations (cases) on the variables.
In this form R2 is expressed as the ratio of the explained varianc... | Coefficient of determination | Wikipedia | 477 | 1500869 | https://en.wikipedia.org/wiki/Coefficient%20of%20determination | Mathematics | Probability | null |
Interpretation
R2 is a measure of the goodness of fit of a model. In regression, the R2 coefficient of determination is a statistical measure of how well the regression predictions approximate the real data points. An R2 of 1 indicates that the regression predictions perfectly fit the data.
Values of R2 outside the r... | Coefficient of determination | Wikipedia | 485 | 1500869 | https://en.wikipedia.org/wiki/Coefficient%20of%20determination | Mathematics | Probability | null |
In a multiple linear model
Consider a linear model with more than a single explanatory variable, of the form
where, for the ith case, is the response variable, are p regressors, and is a mean zero error term. The quantities are unknown coefficients, whose values are estimated by least squares. The coefficient of... | Coefficient of determination | Wikipedia | 468 | 1500869 | https://en.wikipedia.org/wiki/Coefficient%20of%20determination | Mathematics | Probability | null |
Inflation of R2
In least squares regression using typical data, R2 is at least weakly increasing with an increase in number of regressors in the model. Because increases in the number of regressors increase the value of R2, R2 alone cannot be used as a meaningful comparison of models with very different numbers of ind... | Coefficient of determination | Wikipedia | 404 | 1500869 | https://en.wikipedia.org/wiki/Coefficient%20of%20determination | Mathematics | Probability | null |
A simple case to be considered first:
This equation describes the ordinary least squares regression model with one regressor. The prediction is shown as the red vector in the figure on the right. Geometrically, it is the projection of true value onto a model space in (without intercept). The residual is shown as the... | Coefficient of determination | Wikipedia | 416 | 1500869 | https://en.wikipedia.org/wiki/Coefficient%20of%20determination | Mathematics | Probability | null |
The use of an adjusted R2 (one common notation is , pronounced "R bar squared"; another is or ) is an attempt to account for the phenomenon of the R2 automatically increasing when extra explanatory variables are added to the model. There are many different ways of adjusting. By far the most used one, to the point that... | Coefficient of determination | Wikipedia | 370 | 1500869 | https://en.wikipedia.org/wiki/Coefficient%20of%20determination | Mathematics | Probability | null |
The adjusted R2 can be interpreted as an instance of the bias-variance tradeoff. When we consider the performance of a model, a lower error represents a better performance. When the model becomes more complex, the variance will increase whereas the square of bias will decrease, and these two metrices add up to be the t... | Coefficient of determination | Wikipedia | 475 | 1500869 | https://en.wikipedia.org/wiki/Coefficient%20of%20determination | Mathematics | Probability | null |
Following the same logic, adjusted R2 can be interpreted as a less biased estimator of the population R2, whereas the observed sample R2 is a positively biased estimate of the population value. Adjusted R2 is more appropriate when evaluating model fit (the variance in the dependent variable accounted for by the indepen... | Coefficient of determination | Wikipedia | 416 | 1500869 | https://en.wikipedia.org/wiki/Coefficient%20of%20determination | Mathematics | Probability | null |
As explained above, model selection heuristics such as the adjusted R2 criterion and the F-test examine whether the total R2 sufficiently increases to determine if a new regressor should be added to the model. If a regressor is added to the model that is highly correlated with other regressors which have already been i... | Coefficient of determination | Wikipedia | 494 | 1500869 | https://en.wikipedia.org/wiki/Coefficient%20of%20determination | Mathematics | Probability | null |
R2 in logistic regression
In the case of logistic regression, usually fit by maximum likelihood, there are several choices of pseudo-R2.
One is the generalized R2 originally proposed by Cox & Snell, and independently by Magee:
where is the likelihood of the model with only the intercept, is the likelihood of the ... | Coefficient of determination | Wikipedia | 506 | 1500869 | https://en.wikipedia.org/wiki/Coefficient%20of%20determination | Mathematics | Probability | null |
R2 = 0.998, and norm of residuals = 0.302.
If all values of y are multiplied by 1000 (for example, in an SI prefix change), then R2 remains the same, but norm of residuals = 302.
Another single-parameter indicator of fit is the RMSE of the residuals, or standard deviation of the residuals. This would have a value of 0... | Coefficient of determination | Wikipedia | 128 | 1500869 | https://en.wikipedia.org/wiki/Coefficient%20of%20determination | Mathematics | Probability | null |
SN 1006 was a supernova that is likely the brightest observed stellar event in recorded history, reaching an estimated −7.5 visual magnitude, and exceeding roughly sixteen times the brightness of Venus. Appearing between April 30 and May 1, 1006, in the constellation of Lupus, this "guest star" was described by observe... | SN 1006 | Wikipedia | 497 | 1501313 | https://en.wikipedia.org/wiki/SN%201006 | Physical sciences | Notable transient events | Astronomy |
According to Songshi, the official history of the Song dynasty (sections 56 and 461), the star seen on May 1, 1006, appeared to the south of constellation Di, between Lupus and Centaurus. It shone so brightly that objects on the ground could be seen at night.
By December, it was again sighted in the constellation Di. ... | SN 1006 | Wikipedia | 347 | 1501313 | https://en.wikipedia.org/wiki/SN%201006 | Physical sciences | Notable transient events | Astronomy |
SN 1006's associated supernova remnant from this event was not identified until 1965, when Doug Milne and Frank Gardner used the Parkes radio telescope to demonstrate a connection to known radio source PKS 1459−41.
This is located near the star Beta Lupi, displaying a 30 arcmin circular shell.
X-ray and optical emissio... | SN 1006 | Wikipedia | 337 | 1501313 | https://en.wikipedia.org/wiki/SN%201006 | Physical sciences | Notable transient events | Astronomy |
Destructive distillation is a chemical process in which decomposition of unprocessed material is achieved by heating it to a high temperature; the term generally applies to processing of organic material in the absence of air or in the presence of limited amounts of oxygen or other reagents, catalysts, or solvents, su... | Destructive distillation | Wikipedia | 470 | 1501800 | https://en.wikipedia.org/wiki/Destructive%20distillation | Physical sciences | Other reactions | Chemistry |
Process
The process of pyrolysis can be conducted in a distillation apparatus (retort) to form the volatile products for collection. The mass of the product will represent only a part of the mass of the feedstock, because much of the material remains as char, ash, and non-volatile tars. In contrast, combustion consumes... | Destructive distillation | Wikipedia | 266 | 1501800 | https://en.wikipedia.org/wiki/Destructive%20distillation | Physical sciences | Other reactions | Chemistry |
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephalians included herbivorous, carnivorous, and omnivorous forms. Many species ... | Dinocephalia | Wikipedia | 386 | 1502780 | https://en.wikipedia.org/wiki/Dinocephalia | Biology and health sciences | Proto-mammals | Animals |
Skull
All dinocephalians are distinguished by the interlocking incisor (front) teeth. Correlated features are the distinctly downturned facial region, a deep temporal region, and forwardly rotated suspensorium. Shearing contact between the upper and lower teeth (allowing food to be more easily sliced into small bits fo... | Dinocephalia | Wikipedia | 439 | 1502780 | https://en.wikipedia.org/wiki/Dinocephalia | Biology and health sciences | Proto-mammals | Animals |
At the height of their diversity (middle or late Capitanian age) all the dinocephalians suddenly died out, during the Capitanian mass extinction event. The reason for their extinction is not clear; although disease, sudden climatic change, or other factors of environmental stress may have brought about their end. They ... | Dinocephalia | Wikipedia | 254 | 1502780 | https://en.wikipedia.org/wiki/Dinocephalia | Biology and health sciences | Proto-mammals | Animals |
Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy needed for deformation (or movement) of the wheel, roadbed, etc., is recovered... | Rolling resistance | Wikipedia | 453 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
A characteristic of a deformable material such that the energy of deformation is greater than the energy of recovery. The rubber compound in a tire exhibits hysteresis. As the tire rotates under the weight of the vehicle, it experiences repeated cycles of deformation and recovery, and it dissipates the hysteresis energ... | Rolling resistance | Wikipedia | 400 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
Definitions
In the broad sense, specific "rolling resistance" (for vehicles) is the force per unit vehicle weight required to move the vehicle on level ground at a constant slow speed where aerodynamic drag (air resistance) is insignificant and also where there are no traction (motor) forces or brakes applied. In other... | Rolling resistance | Wikipedia | 498 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
For highway motor vehicles, there is some energy dissipated in shaking the roadway (and the earth beneath it), the shaking of the vehicle itself, and the sliding of the tires. But, other than the additional power required due to torque and wheel bearing friction, non-pure rolling resistance doesn't seem to have been in... | Rolling resistance | Wikipedia | 154 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
is the force needed to push (or tow) a wheeled vehicle forward (at constant speed on a level surface, or zero grade, with zero air resistance) per unit force of weight. It is assumed that all wheels are the same and bear identical weight. Thus: means that it would only take 0.01 pounds to tow a vehicle weighing one po... | Rolling resistance | Wikipedia | 452 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
"Rolling resistance coefficient (RRC). The value of the rolling resistance force divided by the wheel load. The Society of Automotive Engineers (SAE) has developed test practices to measure the RRC of tires. These tests (SAE J1269 and SAE J2452) are usually performed on new tires. When measured by using these standard ... | Rolling resistance | Wikipedia | 412 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
The above equation, where resistance is inversely proportional to radius seems to be based on the discredited "Coulomb's law" (Neither Coulomb's inverse square law nor Coulomb's law of friction). See dependence on diameter. Equating this equation with the force per the rolling resistance coefficient, and solving for ,... | Rolling resistance | Wikipedia | 407 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
where
is the linear speed of the body (at the axle), and
its rotational speed.
It is noteworthy that is usually not equal to the radius of the rolling body as a result of wheel slip. The slip between wheel and ground inevitably occurs whenever a driving or braking torque is applied to the wheel. Consequently, the ... | Rolling resistance | Wikipedia | 485 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
It is shown that for a passenger car, when the tractive force is about 40% of the maximum traction, the slip resistance is almost equal to the basic rolling resistance (hysteresis loss). But in case of a tractive force equal to 70% of the maximum traction, slip resistance becomes 10 times larger than the basic rolling ... | Rolling resistance | Wikipedia | 468 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
Pneumatic tires
For pneumatic tires, the direction of change in Crr (rolling resistance coefficient) depends on whether or not tire inflation is increased with increasing load. It is reported that, if inflation pressure is increased with load according to an (undefined) "schedule", then a 20% increase in load decreases... | Rolling resistance | Wikipedia | 387 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
Factors that contribute in tires
Several factors affect the magnitude of rolling resistance a tire generates:
As mentioned in the introduction: wheel radius, forward speed, surface adhesion, and relative micro-sliding.
Material - different fillers and polymers in tire composition can improve traction while reducing h... | Rolling resistance | Wikipedia | 509 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
Virtually all world speed records have been set on relatively narrow wheels, probably because of their aerodynamic advantage at high speed, which is much less important at normal speeds.
Temperature: with both solid and pneumatic tires, rolling resistance has been found to decrease as temperature increases (within a r... | Rolling resistance | Wikipedia | 117 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
Railroads: Components of rolling resistance
In a broad sense rolling resistance can be defined as the sum of components):
Wheel bearing torque losses.
Pure rolling resistance.
Sliding of the wheel on the rail.
Loss of energy to the roadbed (and earth).
Loss of energy to oscillation of railway rolling stock.
Wh... | Rolling resistance | Wikipedia | 474 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
In the case of freight, CSX ran an advertisement campaign in 2013 claiming that their freight trains move "a ton of freight 436 miles on a gallon of fuel", whereas some sources claim trucks move a ton of freight about 130 miles per gallon of fuel, indicating trains are more efficient overall. | Rolling resistance | Wikipedia | 60 | 1503750 | https://en.wikipedia.org/wiki/Rolling%20resistance | Physical sciences | Classical mechanics | Physics |
Tip of the red-giant branch (TRGB) is a primary distance indicator used in astronomy. It uses the luminosity of the brightest red-giant-branch stars in a galaxy as a standard candle to gauge the distance to that galaxy. It has been used in conjunction with observations from the Hubble Space Telescope to determine the r... | Tip of the red-giant branch | Wikipedia | 489 | 1505215 | https://en.wikipedia.org/wiki/Tip%20of%20the%20red-giant%20branch | Physical sciences | Basics | Astronomy |
Albedo ( ; ) is the fraction of sunlight that is diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects all incident radiation). Surface albedo is defined as the ratio of radiosity Je to the irradian... | Albedo | Wikipedia | 415 | 39 | https://en.wikipedia.org/wiki/Albedo | Physical sciences | Astrometry | null |
Any albedo in visible light falls within a range of about 0.9 for fresh snow to about 0.04 for charcoal, one of the darkest substances. Deeply shadowed cavities can achieve an effective albedo approaching the zero of a black body. When seen from a distance, the ocean surface has a low albedo, as do most forests, wherea... | Albedo | Wikipedia | 473 | 39 | https://en.wikipedia.org/wiki/Albedo | Physical sciences | Astrometry | null |
White-sky, black-sky, and blue-sky albedo
For land surfaces, it has been shown that the albedo at a particular solar zenith angle θi can be approximated by the proportionate sum of two terms:
the directional-hemispherical reflectance at that solar zenith angle, , sometimes referred to as black-sky albedo, and
the bi-... | Albedo | Wikipedia | 425 | 39 | https://en.wikipedia.org/wiki/Albedo | Physical sciences | Astrometry | null |
The tens of thousands of hectares of greenhouses in Almería, Spain form a large expanse of whitened plastic roofs. A 2008 study found that this anthropogenic change lowered the local surface area temperature of the high-albedo area, although changes were localized. A follow-up study found that "CO2-eq. emissions associ... | Albedo | Wikipedia | 469 | 39 | https://en.wikipedia.org/wiki/Albedo | Physical sciences | Astrometry | null |
The response of the climate system to an initial forcing is modified by feedbacks: increased by "self-reinforcing" or "positive" feedbacks and reduced by "balancing" or "negative" feedbacks. The main reinforcing feedbacks are the water-vapour feedback, the ice–albedo feedback, and the net effect of clouds.
Albedo–temp... | Albedo | Wikipedia | 426 | 39 | https://en.wikipedia.org/wiki/Albedo | Physical sciences | Astrometry | null |
Just as fresh snow has a higher albedo than does dirty snow, the albedo of snow-covered sea ice is far higher than that of sea water. Sea water absorbs more solar radiation than would the same surface covered with reflective snow. When sea ice melts, either due to a rise in sea temperature or in response to increased s... | Albedo | Wikipedia | 317 | 39 | https://en.wikipedia.org/wiki/Albedo | Physical sciences | Astrometry | null |
Solar photovoltaic effects
Albedo can affect the electrical energy output of solar photovoltaic devices. For example, the effects of a spectrally responsive albedo are illustrated by the differences between the spectrally weighted albedo of solar photovoltaic technology based on hydrogenated amorphous silicon (a-Si:H)... | Albedo | Wikipedia | 501 | 39 | https://en.wikipedia.org/wiki/Albedo | Physical sciences | Astrometry | null |
In seasonally snow-covered zones, winter albedos of treeless areas are 10% to 50% higher than nearby forested areas because snow does not cover the trees as readily. Deciduous trees have an albedo value of about 0.15 to 0.18 whereas coniferous trees have a value of about 0.09 to 0.15. Variation in summer albedo across ... | Albedo | Wikipedia | 501 | 39 | https://en.wikipedia.org/wiki/Albedo | Physical sciences | Astrometry | null |
Note that white caps on waves look white (and have high albedo) because the water is foamed up, so there are many superimposed bubble surfaces which reflect, adding up their reflectivities. Fresh 'black' ice exhibits Fresnel reflection.
Snow on top of this sea ice increases the albedo to 0.9.
Clouds
Cloud albedo has s... | Albedo | Wikipedia | 425 | 39 | https://en.wikipedia.org/wiki/Albedo | Physical sciences | Astrometry | null |
Optical or visual albedo
The albedos of planets, satellites and minor planets such as asteroids can be used to infer much about their properties. The study of albedos, their dependence on wavelength, lighting angle ("phase angle"), and variation in time composes a major part of the astronomical field of photometry. For... | Albedo | Wikipedia | 499 | 39 | https://en.wikipedia.org/wiki/Albedo | Physical sciences | Astrometry | null |
An important relationship between an object's astronomical (geometric) albedo, absolute magnitude and diameter is given by:
where is the astronomical albedo, is the diameter in kilometers, and is the absolute magnitude.
Radar albedo
In planetary radar astronomy, a microwave (or radar) pulse is transmitted toward a... | Albedo | Wikipedia | 491 | 39 | https://en.wikipedia.org/wiki/Albedo | Physical sciences | Astrometry | null |
International Atomic Time (abbreviated TAI, from its French name ) is a high-precision atomic coordinate time standard based on the notional passage of proper time on Earth's geoid. TAI is a weighted average of the time kept by over 450 atomic clocks in over 80 national laboratories worldwide. It is a continuous scale ... | International Atomic Time | Wikipedia | 508 | 334 | https://en.wikipedia.org/wiki/International%20Atomic%20Time | Technology | Timekeeping | null |
The clocks at different institutions are regularly compared against each other. The International Bureau of Weights and Measures (BIPM, France), combines these measurements to retrospectively calculate the weighted average that forms the most stable time scale possible. This combined time scale is published monthly i... | International Atomic Time | Wikipedia | 462 | 334 | https://en.wikipedia.org/wiki/International%20Atomic%20Time | Technology | Timekeeping | null |
The SI second was defined in terms of the caesium atom in 1967. From 1971 to 1975 the General Conference on Weights and Measures and the International Committee for Weights and Measures made a series of decisions that designated the BIPM time scale International Atomic Time (TAI).
In the 1970s, it became clear that th... | International Atomic Time | Wikipedia | 384 | 334 | https://en.wikipedia.org/wiki/International%20Atomic%20Time | Technology | Timekeeping | null |
Relation to UTC
Contrary to TAI, UTC is a discontinuous time scale. It is occasionally adjusted by leap seconds. Between these adjustments, it is composed of segments that are mapped to atomic time by a constant offset. From its beginning in 1961 through December 1971, the adjustments were made regularly in fractional... | International Atomic Time | Wikipedia | 161 | 334 | https://en.wikipedia.org/wiki/International%20Atomic%20Time | Technology | Timekeeping | null |
Agricultural science (or agriscience for short) is a broad multidisciplinary field of biology that encompasses the parts of exact, natural, economic and social sciences that are used in the practice and understanding of agriculture. Professionals of the agricultural science are called agricultural scientists or agricul... | Agricultural science | Wikipedia | 416 | 572 | https://en.wikipedia.org/wiki/Agricultural%20science | Technology | Basics | null |
Research topics
Agricultural sciences include research and development on:
Improving agricultural productivity in terms of quantity and quality (e.g., selection of drought-resistant crops and animals, development of new pesticides, yield-sensing technologies, simulation models of crop growth, in-vitro cell culture tec... | Agricultural science | Wikipedia | 307 | 572 | https://en.wikipedia.org/wiki/Agricultural%20science | Technology | Basics | null |
Alchemy (from the Arabic word , ) is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practised in China, India, the Muslim world, and Europe. In its Western form, alchemy is first attested in a number of pseudepigraphical texts written in Greco-Roman Egypt du... | Alchemy | Wikipedia | 400 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Modern discussions of alchemy are generally split into an examination of its exoteric practical applications and its esoteric spiritual aspects, despite criticisms by scholars such as Eric J. Holmyard and Marie-Louise von Franz that they should be understood as complementary. The former is pursued by historians of the ... | Alchemy | Wikipedia | 448 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
History
Alchemy encompasses several philosophical traditions spanning some four millennia and three continents. These traditions' general penchant for cryptic and symbolic language makes it hard to trace their mutual influences and genetic relationships. One can distinguish at least three major strands, which appear t... | Alchemy | Wikipedia | 408 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Recent scholarship tends to emphasize the testimony of Zosimus, who traced the alchemical arts back to Egyptian metallurgical and ceremonial practices. It has also been argued that early alchemical writers borrowed the vocabulary of Greek philosophical schools but did not implement any of its doctrines in a systematic ... | Alchemy | Wikipedia | 451 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Technology
The dawn of Western alchemy is sometimes associated with that of metallurgy, extending back to 3500 BC. Many writings were lost when the Roman emperor Diocletian ordered the burning of alchemical books after suppressing a revolt in Alexandria (AD 292). Few original Egyptian documents on alchemy have survive... | Alchemy | Wikipedia | 483 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Most of the Greco-Roman alchemists preceding Zosimos are known only by pseudonyms, such as Moses, Isis, Cleopatra, Democritus, and Ostanes. Others authors such as Komarios, and Chymes, we only know through fragments of text. After AD 400, Greek alchemical writers occupied themselves solely in commenting on the works of... | Alchemy | Wikipedia | 495 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Two famous early Indian alchemical authors were Nāgārjuna Siddha and Nityanātha Siddha. Nāgārjuna Siddha was a Buddhist monk. His book, Rasendramangalam, is an example of Indian alchemy and medicine. Nityanātha Siddha wrote Rasaratnākara, also a highly influential work. In Sanskrit, rasa translates to "mercury", and Nā... | Alchemy | Wikipedia | 454 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
In the late ninth and early tenth centuries, the Arabic works attributed to Jābir ibn Hayyān (Latinized as "Geber" or "Geberus") introduced a new approach to alchemy. Paul Kraus, who wrote the standard reference work on Jabir, put it as follows:
Islamic philosophers also made great contributions to alchemical hermetic... | Alchemy | Wikipedia | 496 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
From the 14th century onwards, many materials and practices originally belonging to Indian alchemy (Rasayana) were assimilated in the Persian texts written by Muslim scholars.
East Asia
Researchers have found evidence that Chinese alchemists and philosophers discovered complex mathematical phenomena that were shared... | Alchemy | Wikipedia | 268 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
As early as 317 AD, Ge Hong documented the use of metals, minerals, and elixirs in early Chinese medicine. Hong identified three ancient Chinese documents, titled Scripture of Great Clarity, Scripture of the Nine Elixirs, and Scripture of the Golden Liquor, as texts containing fundamental alchemical information. He als... | Alchemy | Wikipedia | 477 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Black powder may have been an important invention of Chinese alchemists. It is said that the Chinese invented gunpowder while trying to find a potion for eternal life. Described in 9th-century texts and used in fireworks in China by the 10th century, it was used in cannons by 1290. From China, the use of gunpowder spre... | Alchemy | Wikipedia | 448 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Meanwhile, theologian contemporaries of the translators made strides towards the reconciliation of faith and experimental rationalism, thereby priming Europe for the influx of alchemical thought. The 11th-century St Anselm put forth the opinion that faith and rationalism were compatible and encouraged rationalism in a ... | Alchemy | Wikipedia | 376 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Roger Bacon, a Franciscan friar who wrote on a wide variety of topics including optics, comparative linguistics, and medicine, composed his Great Work () for as part of a project towards rebuilding the medieval university curriculum to include the new learning of his time. While alchemy was not more important to him t... | Alchemy | Wikipedia | 251 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Soon after Bacon, the influential work of Pseudo-Geber (sometimes identified as Paul of Taranto) appeared. His Summa Perfectionis remained a staple summary of alchemical practice and theory through the medieval and renaissance periods. It was notable for its inclusion of practical chemical operations alongside sulphur-... | Alchemy | Wikipedia | 278 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
In the 14th century, alchemy became more accessible to Europeans outside the confines of Latin-speaking churchmen and scholars. Alchemical discourse shifted from scholarly philosophical debate to an exposed social commentary on the alchemists themselves. Dante, Piers Plowman, and Chaucer all painted unflattering pictur... | Alchemy | Wikipedia | 452 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
In the late 15th century, Marsilio Ficino translated the Corpus Hermeticum and the works of Plato into Latin. These were previously unavailable to Europeans who for the first time had a full picture of the alchemical theory that Bacon had declared absent. Renaissance Humanism and Renaissance Neoplatonism guided alchemi... | Alchemy | Wikipedia | 414 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
John Dee (13 July 1527 – December 1608) followed Agrippa's occult tradition. Although better known for angel summoning, divination, and his role as astrologer, cryptographer, and consultant to Queen Elizabeth I, Dee's alchemical Monas Hieroglyphica, written in 1564 was his most popular and influential work. His writing... | Alchemy | Wikipedia | 427 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
The terms "chemia" and "alchemia" were used as synonyms in the early modern period, and the differences between alchemy, chemistry and small-scale assaying and metallurgy were not as neat as in the present day. There were important overlaps between practitioners, and trying to classify them into alchemists, chemists an... | Alchemy | Wikipedia | 440 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Robert Boyle (1627–1691) pioneered the scientific method in chemical investigations. He assumed nothing in his experiments and compiled every piece of relevant data. Boyle would note the place in which the experiment was carried out, the wind characteristics, the position of the Sun and Moon, and the barometer reading,... | Alchemy | Wikipedia | 356 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Two seminal figures during this period were Mary Anne Atwood and Ethan Allen Hitchcock, who independently published similar works regarding spiritual alchemy. Both rebuffed the growing successes of chemistry, developing a completely esoteric view of alchemy. Atwood wrote: "No modern art or chemistry, notwithstanding al... | Alchemy | Wikipedia | 341 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
The first alchemist whose name we know was Mary the Jewess (). Early sources claim that Mary (or Maria) devised a number of improvements to alchemical equipment and tools as well as novel techniques in chemistry. Her best known advances were in heating and distillation processes. The laboratory water-bath, known eponym... | Alchemy | Wikipedia | 208 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Towards the end of the Middle Ages and beginning of the Renaissance, due to the emergence of print, women were able to access the alchemical knowledge from texts of the preceding centuries. Caterina Sforza, the Countess of Forlì and Lady of Imola, is one of the few confirmed female alchemists after Mary the Jewess. As ... | Alchemy | Wikipedia | 351 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Some women known for their interest in alchemy were Catherine de' Medici, the Queen of France, and Marie de' Medici, the following Queen of France, who carried out experiments in her personal laboratory. Also, Isabella d'Este, the Marchioness of Mantua, made perfumes herself to serve as gifts. Due to the proliferation ... | Alchemy | Wikipedia | 388 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Modern historical research
The history of alchemy has become a recognized subject of academic study. As the language of the alchemists is analysed, historians are becoming more aware of the connections between that discipline and other facets of Western cultural history, such as the evolution of science and philosophy... | Alchemy | Wikipedia | 409 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Modernity
Due to the complexity and obscurity of alchemical literature, and the 18th-century diffusion of remaining alchemical practitioners into the area of chemistry, the general understanding of alchemy in the 19th and 20th centuries was influenced by several distinct and radically different interpretations. Those ... | Alchemy | Wikipedia | 346 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
According to this view, early alchemists such as Zosimos of Panopolis () highlighted the spiritual nature of the alchemical quest, symbolic of a religious regeneration of the human soul. This approach is held to have continued in the Middle Ages, as metaphysical aspects, substances, physical states, and material proces... | Alchemy | Wikipedia | 311 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Psychology
Alchemical symbolism has been important in analytical psychology and was revived and popularized from near extinction by the Swiss psychologist Carl Gustav Jung. Jung was initially confounded and at odds with alchemy and its images but after being given a copy of The Secret of the Golden Flower, a Chinese a... | Alchemy | Wikipedia | 512 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
Visual artists have had a similar relationship with alchemy. While some used it as a source of satire, others worked with the alchemists themselves or integrated alchemical thought or symbols in their work. Music was also present in the works of alchemists and continues to influence popular performers. In the last hund... | Alchemy | Wikipedia | 149 | 573 | https://en.wikipedia.org/wiki/Alchemy | Physical sciences | Chemistry: General | null |
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