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Cornhole	Rules and format	In cornhole, cancellation scoring is used. When the scores are tallied at the end of an inning, whichever player or team scores higher is awarded points equal to the difference between both sides. For example, if Team A scores 12 points in an inning and Team B scores 10 points, then Team A is awarded two points (12 minus 10); whereas if Team A and Team B both score 12 points, the difference is zero, and no one scores. Play continues until one player or team reaches or exceeds 21 points at the end of an inning. By using cancellation scoring, it is only possible for one side (or neither side) to score in any inning, so match ties are impossible.
Cornhole	Rules and format	Different variations in scoring or house rules are sometimes used. Sometimes, a bag hanging over the hole, but which has not fallen through, is scored as two points. Other variations include requiring one team to reach exactly 21 points without going over to win. If a team exceeds 21 points after an inning (called "busting"), different punishments might be used such as automatically returning to 15 points, returning to the team's prior score, returning to the prior score minus one, etc. In some versions, if a team "busts" three times, their opponents automatically win the match.
Cornhole	Rules and format	Strategy Gameplay strategy varies by player and skill level. At the professional level, players can easily slide all four bags into the hole if no bag blocks the path. Defensive strategies are often employed to slow down gameplay or force opponents to make difficult decisions. Defensive plays might include throwing a blocker bag that rests in front of the hole, thereby forcing an opponent to either slide through the blocker bag to reach the hole, throw another blocker behind the bag, or attempt a risky airmail shot over the bag aiming directly for the hole without touching the board.
Cornhole	Terminology	The following is a list of terms commonly used in cornhole: Airmail: a bag that does not slide or bounce on the board but goes directly into the hole, usually over an opponent's blocker bag. Back door, jumper, dirty rollup: a bag that goes over the top of a blocker and into the hole. Backstop: a bag that lands past the hole but remains on the board creating a backboard for a slider to knock into without going off the board. Blocker: a bag that lands in front of the hole, blocking the hole from an opponent's slide shot. Busting: an unofficial rule that sends a player's score back down to a predetermined number if their score at the end of an inning exceeds 21. Cornfusion: when players or teams cannot agree on the scoring of an inning. Cornhole or Drano: a bag that falls in the hole and is worth three points; the alternative name is a reference to a trademark, that of a clog-clearing product. Cornholio: same as "cornhole", depending on the region; named for the alter-ego of the character Beavis from the MTV animated series Beavis and Butt-Head. Dirt bag: a bag that is on the ground or is hanging off the board and touching the ground.
Cornhole	Terminology	Frame: an inning, a single round during which a player or team and their opponent(s) all throw their bags Four bagger, Grand Bag: a sequence wherein a player makes all four bags in the hole during an inning; more specifically, all bags have to go into the hole one bag after another by the player in a single inning, i.e. the bags cannot later be knocked from the board's surface into the hole during the inning, either by the player or their opponent; there is a tradition in some areas where any social player who puts all four bags in the hole in a single inning gets to sign the board, often with some type of ceremony and recognition.
Cornhole	Terminology	Flop bag, floppy bag: type of toss that does not spin the bag horizontally or vertically, a bag without rotation or spin. Hammer: when one or more hangers (see below) are around the hole, a hammer can be used; a hammer is a bag thrown as an airmail bag with a high arc in an attempt to move hanger bags into the hole along with it. Hanger: a bag on the lip of the hole close to falling in. Honors: the player or team who tosses first, resulting from the team scoring in the previous inning or winning the coin toss before the first inning. Hooker: a bag that hits the board and while hooking or curving around a blocker goes into the hole. Jumper: a bag that strikes another bag on the board causing it to jump up and into the hole. Push, wash: when each player or team obtains an identical score in an inning resulting in no overall score change Short bag: when a bag lands on the ground just before the board. Skunk, whitewash, shutout: a game that ends in a score of 21 (or more) to zero; by some unofficial rules a game may be called once a shutout score of at least 11–0 is reached. Slide, slider: a bag that lands in front of the hole and slides in. Swish: a bag that goes directly in the hole without touching the board (see also: "airmail"). Woody: any bag that has been pitched and remains on the board's surface at the end of the inning (scoring one point).
Capacity factor	Capacity factor	The net capacity factor is the unitless ratio of actual electrical energy output over a given period of time to the theoretical maximum electrical energy output over that period. The theoretical maximum energy output of a given installation is defined as that due to its continuous operation at full nameplate capacity over the relevant period. The capacity factor can be calculated for any electricity producing installation, such as a fuel consuming power plant or one using renewable energy, such as wind or the sun. The average capacity factor can also be defined for any class of such installations, and can be used to compare different types of electricity production.
Capacity factor	Capacity factor	The actual energy output during that period and the capacity factor vary greatly depending on a range of factors. The capacity factor can never exceed the availability factor, or uptime during the period. Uptime can be reduced due to, for example, reliability issues and maintenance, scheduled or unscheduled. Other factors include the design of the installation, its location, the type of electricity production and with it either the fuel being used or, for renewable energy, the local weather conditions. Additionally, the capacity factor can be subject to regulatory constraints and market forces, potentially affecting both its fuel purchase and its electricity sale.
Capacity factor	Capacity factor	The capacity factor is often computed over a timescale of a year, averaging out most temporal fluctuations. However, it can also be computed for a month to gain insight into seasonal fluctuations. Alternatively, it can be computed over the lifetime of the power source, both while operational and after decommissioning. A capacity factor can also be expressed and converted to full load hours.
Capacity factor	Sample calculations	Nuclear power plant Nuclear power plants are at the high end of the range of capacity factors, ideally reduced only by the availability factor, i.e. maintenance and refueling. The largest nuclear plant in the US, Palo Verde Nuclear Generating Station has between its three reactors a nameplate capacity of 3,942 MW. In 2010 its annual generation was 31,200,000 MWh, leading to a capacity factor of: 31 200 000 MW·h 365 days 24 hours/day 3942 MW 0.904 90.4 % Each of Palo Verde’s three reactors is refueled every 18 months, with one refueling every spring and fall. In 2014, a refueling was completed in a record 28 days, compared to the 35 days of downtime that the 2010 capacity factor corresponds to.
Capacity factor	Sample calculations	In 2019, Prairie Island 1 was the US unit with the highest factor and actually reached 104.4%. Wind farm The Danish offshore wind farm Horns Rev 2 has a nameplate capacity of 209.3 MW.
Capacity factor	Sample calculations	As of January 2017 it has produced 6416 GWh since its commissioning 7 years ago, i.e. an average annual production of 875 GWh/year and a capacity factor of: 875 000 MW·h 365 days 24 hours/day 209.3 MW 0.477 47.7 % Sites with lower capacity factors may be deemed feasible for wind farms, for example the onshore 1 GW Fosen Vind which as of 2017 is under construction in Norway has a projected capacity factor of 39%. Feasibility calculations may be affected by seasonality. For example in Finland, capacity factor during the cold winter months is more than double compared to July. While the annual average in Finland is 29.5%, the high demand for heating energy correlates with the higher capacity factor during the winter.
Capacity factor	Sample calculations	Certain onshore wind farms can reach capacity factors of over 60%, for example the 44 MW Eolo plant in Nicaragua had a net generation of 232.132 GWh in 2015, equivalent to a capacity factor of 60.2%, while United States annual capacity factors from 2013 through 2016 range from 32.2% to 34.7%.Since the capacity factor of a wind turbine measures actual production relative to possible production, it is unrelated to Betz's coefficient of 16/27 ≈ 59.3%, which limits production vs. energy available in the wind.
Capacity factor	Sample calculations	Hydroelectric dam As of 2017 the Three Gorges Dam in China is, with its nameplate capacity of 22,500 MW, the largest power generating station in the world by installed capacity. In 2015 it generated 87 TWh, for a capacity factor of: 87 000 000 MW·h 365 days 24 hours/day 22 500 MW 0.45 45 % Hoover Dam has a nameplate capacity of 2080 MW and an annual generation averaging 4.2 TW·h. (The annual generation has varied between a high of 10.348 TW·h in 1984, and a low of 2.648 TW·h in 1956.).
Capacity factor	Sample calculations	Taking the average figure for annual generation gives a capacity factor of: 200 000 MW·h 365 days 24 hours/day 080 MW 0.23 23 % Photovoltaic power station At the low range of capacity factors is the photovoltaic power station, which supplies power to the electricity grid from a large-scale photovoltaic system (PV system). An inherent limit to its capacity factor comes from its requirement of daylight, preferably with a sun unobstructed by clouds, smoke or smog, shade from trees and building structures. Since the amount of sunlight varies both with the time of the day and the seasons of the year, the capacity factor is typically computed on an annual basis. The amount of available sunlight is mostly determined by the latitude of the installation and the local cloud cover.
Capacity factor	Sample calculations	The actual production is also influenced by local factors such as dust and ambient temperature, which ideally should be low. As for any power station, the maximum possible power production is the nameplate capacity times the number of hours in a year, while the actual production is the amount of electricity delivered annually to the grid. For example, Agua Caliente Solar Project, located in Arizona near the 33rd parallel and awarded for its excellence in renewable energy has a nameplate capacity of 290 MW and an actual average annual production of 740 GWh/year. Its capacity factor is thus: 740 000 MW·h 365 days 24 hours/day 290 MW 0.291 29.1 % .A significantly lower capacity factor is achieved by Lauingen Energy Park located in Bavaria, near the 49th parallel. With a nameplate capacity of 25.7 MW and an actual average annual production of 26.98 GWh/year it has a capacity factor of 12.0%.
Capacity factor	Determinants of a plant capacity factor	There are several reasons why a plant would have a capacity factor lower than 100%. These include technical constraints, such as availability of the plant, economic reasons, and availability of the energy resource.
Capacity factor	Determinants of a plant capacity factor	A plant can be out of service or operating at reduced output for part of the time due to equipment failures or routine maintenance. This accounts for most of the unused capacity of base load power plants. Base load plants usually have low costs per unit of electricity because they are designed for maximum efficiency and are operated continuously at high output.
Capacity factor	Determinants of a plant capacity factor	Geothermal power plants, nuclear power plants, coal-fired plants and bioenergy plants that burn solid material are almost always operated as base load plants, as they can be difficult to adjust to suit demand. A plant can also have its output curtailed or intentionally left idle because the electricity is not needed or because the price of electricity is too low to make production economical. This accounts for most of the unused capacity of peaking power plants and load following power plants. Peaking plants may operate for only a few hours per year or up to several hours per day. Many other power plants operate only at certain times of the day or year because of variation in loads and electricity prices. If a plant is only needed during the day, for example, even if it operates at full power output from 8 am to 8 pm every day (12 hours) all year long, it would only have a 50% capacity factor. Due to low capacity factors, electricity from peaking power plants is relatively expensive because the limited generation has to cover the plant fixed costs. A third reason is that a plant may not have the fuel available to operate all of the time. This can apply to fossil generating stations with restricted fuels supplies, but most notably applies to intermittent renewable resources. Solar PV and wind turbines have a capacity factor limited by the availability of their "fuel", sunshine and wind respectively. A hydroelectricity plant may have a capacity factor lower than 100% due to restriction or scarcity of water, or its output may be regulated to match the current power need, conserving its stored water for later usage. Other reasons that a power plant may not have a capacity factor of 100% include restrictions or limitations on air permits and limitations on transmission that force the plant to curtail output.
Capacity factor	Capacity factor of renewable energy	For renewable energy sources such as solar power, wind power and hydroelectricity, the main reason for reduced capacity factor is generally the availability of the energy source. The plant may be capable of producing electricity, but its "fuel" (wind, sunlight or water) may not be available. A hydroelectric plant's production may also be affected by requirements to keep the water level from getting too high or low and to provide water for fish downstream. However, solar, wind and hydroelectric plants do have high availability factors, so when they have fuel available, they are almost always able to produce electricity.When hydroelectric plants have water available, they are also useful for load following, because of their high dispatchability. A typical hydroelectric plant's operators can bring it from a stopped condition to full power in just a few minutes.
Capacity factor	Capacity factor of renewable energy	Wind farms are variable, due to the natural variability of the wind. For a wind farm, the capacity factor is determined by the availability of wind, the swept area of the turbine and the size of the generator. Transmission line capacity and electricity demand also affect the capacity factor. Typical capacity factors of current wind farms are between 25 and 45%. In the United Kingdom during the five year period from 2011 to 2019 the annual capacity factor for wind was over 30%.Solar energy is variable because of the daily rotation of the earth, seasonal changes, and because of cloud cover. For example, the Sacramento Municipal Utility District observed a 15% capacity factor in 2005.
Capacity factor	Capacity factor of renewable energy	However, according to the SolarPACES programme of the International Energy Agency (IEA), solar power plants designed for solar-only generation are well matched to summer noon peak loads in areas with significant cooling demands, such as Spain or the south-western United States, although in some locations solar PV does not reduce the need for generation of network upgrades given that air conditioner peak demand often occurs in the late afternoon or early evening when solar output is reduced. SolarPACES states that by using thermal energy storage systems the operating periods of solar thermal power (CSP) stations can be extended to become dispatchable (load following).Geothermal has a higher capacity factor than many other power sources, and geothermal resources are generally available all the time.
Capacity factor	Capacity factors by energy source	Worldwide Nuclear power 88.7% (2006 - 2012 average of US's plants). Hydroelectricity, worldwide average 44%, range of 10% - 99% depending on water availability (with or without regulation via storage dam). Wind farms 20-40%. CSP solar with storage and Natural Gas backup in Spain 63%, California 33%. Photovoltaic solar in Germany 10%, Arizona 19%, Massachusetts 13.35% (8 year average as of July 2018). United States According to the US Energy Information Administration (EIA), from 2013 to 2017 the capacity factors of utility-scale generators were as follows: However, these values often vary significantly by month. United Kingdom The following figures were collected by the Department of Energy and Climate Change on the capacity factors for various types of plants in UK grid:
Acoustic theory	Acoustic theory	Acoustic theory is a scientific field that relates to the description of sound waves. It derives from fluid dynamics. See acoustics for the engineering approach.
Acoustic theory	Acoustic theory	For sound waves of any magnitude of a disturbance in velocity, pressure, and density we have (Conservation of Mass) (Equation of Motion) In the case that the fluctuations in velocity, density, and pressure are small, we can approximate these as ∂ρ′∂t+ρ0∇⋅v=0∂v∂t+1ρ0∇p′=0 Where v(x,t) is the perturbed velocity of the fluid, p0 is the pressure of the fluid at rest, p′(x,t) is the perturbed pressure of the system as a function of space and time, ρ0 is the density of the fluid at rest, and ρ′(x,t) is the variance in the density of the fluid over space and time.
Acoustic theory	Acoustic theory	In the case that the velocity is irrotational ( ∇×v=0 ), we then have the acoustic wave equation that describes the system: 1c2∂2ϕ∂t2−∇2ϕ=0 Where we have v=−∇ϕc2=(∂p∂ρ)sp′=ρ0∂ϕ∂tρ′=ρ0c2∂ϕ∂t
Acoustic theory	Derivation for a medium at rest	Starting with the Continuity Equation and the Euler Equation: ∂ρ∂t+∇⋅ρv=0ρ∂v∂t+ρ(v⋅∇)v+∇p=0 If we take small perturbations of a constant pressure and density: ρ=ρ0+ρ′p=p0+p′ Then the equations of the system are ∂∂t(ρ0+ρ′)+∇⋅(ρ0+ρ′)v=0(ρ0+ρ′)∂v∂t+(ρ0+ρ′)(v⋅∇)v+∇(p0+p′)=0 Noting that the equilibrium pressures and densities are constant, this simplifies to ∂ρ′∂t+ρ0∇⋅v+∇⋅ρ′v=0(ρ0+ρ′)∂v∂t+(ρ0+ρ′)(v⋅∇)v+∇p′=0 A Moving Medium Starting with ∂ρ′∂t+ρ0∇⋅w+∇⋅ρ′w=0(ρ0+ρ′)∂w∂t+(ρ0+ρ′)(w⋅∇)w+∇p′=0 We can have these equations work for a moving medium by setting w=u+v , where u is the constant velocity that the whole fluid is moving at before being disturbed (equivalent to a moving observer) and v is the fluid velocity.
Acoustic theory	Derivation for a medium at rest	In this case the equations look very similar: ∂ρ′∂t+ρ0∇⋅v+u⋅∇ρ′+∇⋅ρ′v=0(ρ0+ρ′)∂v∂t+(ρ0+ρ′)(u⋅∇)v+(ρ0+ρ′)(v⋅∇)v+∇p′=0 Note that setting u=0 returns the equations at rest.
Acoustic theory	Linearized Waves	Starting with the above given equations of motion for a medium at rest: ∂ρ′∂t+ρ0∇⋅v+∇⋅ρ′v=0(ρ0+ρ′)∂v∂t+(ρ0+ρ′)(v⋅∇)v+∇p′=0 Let us now take v,ρ′,p′ to all be small quantities.
Acoustic theory	Linearized Waves	In the case that we keep terms to first order, for the continuity equation, we have the ρ′v term going to 0. This similarly applies for the density perturbation times the time derivative of the velocity. Moreover, the spatial components of the material derivative go to 0. We thus have, upon rearranging the equilibrium density: ∂ρ′∂t+ρ0∇⋅v=0∂v∂t+1ρ0∇p′=0 Next, given that our sound wave occurs in an ideal fluid, the motion is adiabatic, and then we can relate the small change in the pressure to the small change in the density by p′=(∂p∂ρ0)sρ′ Under this condition, we see that we now have ∂p′∂t+ρ0(∂p∂ρ0)s∇⋅v=0∂v∂t+1ρ0∇p′=0 Defining the speed of sound of the system: c≡(∂p∂ρ0)s Everything becomes ∂p′∂t+ρ0c2∇⋅v=0∂v∂t+1ρ0∇p′=0 For Irrotational Fluids In the case that the fluid is irrotational, that is ∇×v=0 , we can then write v=−∇ϕ and thus write our equations of motion as ∂p′∂t−ρ0c2∇2ϕ=0−∇∂ϕ∂t+1ρ0∇p′=0 The second equation tells us that p′=ρ0∂ϕ∂t And the use of this equation in the continuity equation tells us that ρ0∂2ϕ∂t−ρ0c2∇2ϕ=0 This simplifies to 1c2∂2ϕ∂t2−∇2ϕ=0 Thus the velocity potential ϕ obeys the wave equation in the limit of small disturbances. The boundary conditions required to solve for the potential come from the fact that the velocity of the fluid must be 0 normal to the fixed surfaces of the system.
Acoustic theory	Linearized Waves	Taking the time derivative of this wave equation and multiplying all sides by the unperturbed density, and then using the fact that p′=ρ0∂ϕ∂t tells us that 1c2∂2p′∂t2−∇2p′=0 Similarly, we saw that p′=(∂p∂ρ0)sρ′=c2ρ′ . Thus we can multiply the above equation appropriately and see that 1c2∂2ρ′∂t2−∇2ρ′=0 Thus, the velocity potential, pressure, and density all obey the wave equation. Moreover, we only need to solve one such equation to determine all other three. In particular, we have v=−∇ϕp′=ρ0∂ϕ∂tρ′=ρ0c2∂ϕ∂t For a moving medium Again, we can derive the small-disturbance limit for sound waves in a moving medium. Again, starting with ∂ρ′∂t+ρ0∇⋅v+u⋅∇ρ′+∇⋅ρ′v=0(ρ0+ρ′)∂v∂t+(ρ0+ρ′)(u⋅∇)v+(ρ0+ρ′)(v⋅∇)v+∇p′=0 We can linearize these into ∂ρ′∂t+ρ0∇⋅v+u⋅∇ρ′=0∂v∂t+(u⋅∇)v+1ρ0∇p′=0 For Irrotational Fluids in a Moving Medium Given that we saw that ∂ρ′∂t+ρ0∇⋅v+u⋅∇ρ′=0∂v∂t+(u⋅∇)v+1ρ0∇p′=0 If we make the previous assumptions of the fluid being ideal and the velocity being irrotational, then we have p′=(∂p∂ρ0)sρ′=c2ρ′v=−∇ϕ Under these assumptions, our linearized sound equations become 1c2∂p′∂t−ρ0∇2ϕ+1c2u⋅∇p′=0−∂∂t(∇ϕ)−(u⋅∇)[∇ϕ]+1ρ0∇p′=0 Importantly, since u is a constant, we have (u⋅∇)[∇ϕ]=∇[(u⋅∇)ϕ] , and then the second equation tells us that 1ρ0∇p′=∇[∂ϕ∂t+(u⋅∇)ϕ] Or just that p′=ρ0[∂ϕ∂t+(u⋅∇)ϕ] Now, when we use this relation with the fact that 1c2∂p′∂t−ρ0∇2ϕ+1c2u⋅∇p′=0 , alongside cancelling and rearranging terms, we arrive at 1c2∂2ϕ∂t2−∇2ϕ+1c2∂∂t[(u⋅∇)ϕ]+1c2∂∂t(u⋅∇ϕ)+1c2u⋅∇[(u⋅∇)ϕ]=0 We can write this in a familiar form as [1c2(∂∂t+u⋅∇)2−∇2]ϕ=0 This differential equation must be solved with the appropriate boundary conditions. Note that setting u=0 returns us the wave equation. Regardless, upon solving this equation for a moving medium, we then have v=−∇ϕp′=ρ0(∂∂t+u⋅∇)ϕρ′=ρ0c2(∂∂t+u⋅∇)ϕ
Folch solution	Folch solution	A Folch solution is a solution containing chloroform and methanol, usually in a 2:1 (vol/vol) ratio. One of its uses is in separating polar from nonpolar compounds, for example separating nonpolar lipids from polar proteins and carbohydrates in blood serum.
Fire adaptations	Fire adaptations	Fire adaptations are traits of plants and animals that help them survive wildfire or to use resources created by wildfire. These traits can help plants and animals increase their survival rates during a fire and/or reproduce offspring after a fire. Both plants and animals have multiple strategies for surviving and reproducing after fire. Plants in wildfire-prone ecosystems often survive through adaptations to their local fire regime. Such adaptations include physical protection against heat, increased growth after a fire event, and flammable materials that encourage fire and may eliminate competition.
Fire adaptations	Fire adaptations	For example, plants of the genus Eucalyptus contain flammable oils that encourage fire and hard sclerophyll leaves to resist heat and drought, ensuring their dominance over less fire-tolerant species. Dense bark, shedding lower branches, and high water content in external structures may also protect trees from rising temperatures. Fire-resistant seeds and reserve shoots that sprout after a fire encourage species preservation, as embodied by pioneer species. Smoke, charred wood, and heat can stimulate the germination of seeds in a process called serotiny. Exposure to smoke from burning plants promotes germination in other types of plants by inducing the production of the orange butenolide.
Fire adaptations	Plant adaptations to fire	Unlike animals, plants are not able to move physically during a fire. However, plants have their own ways to survive a fire event or recover after a fire. The strategies can be classified into three types: resist (above-ground parts survive fire), recover (evade mortality by sprouting), and recruit (seed germination after the fire). Fire plays a role as a filter that can select different fire response traits.
Fire adaptations	Plant adaptations to fire	Resist Thick bark Fire impacts plants most directly via heat damage. However, new studies indicate that hydraulic failure kills trees during a fire in addition to fire scorching. High temperature cuts the water supply to the canopy and causes the death of the tree. Fortunately, thick bark can protect plants because they keep stems away from high temperature. Under the protection of bark, living tissue won't have direct contact with fire and the survival rate of plants will be increased. Heat resistance is a function of bark thermal diffusivity (a property of the species) and bark thickness (increasing exponentially with bark thickness). Thick bark is common in species adapted to surface or low-severity fire regimes. On the other hand, plants in crown or high-severity fire regimes usually have thinner barks because it is meaningless to invest in thick bark without it conferring an advantage in survivorship.
Fire adaptations	Plant adaptations to fire	Self-pruning branches Self-pruning is another trait of plants to resist fires. Self-pruning branches can reduce the chance for surface fire to reach the canopy because ladder fuels are removed. Self-pruning branches are common in surface or low-severity fire regimes.
Fire adaptations	Plant adaptations to fire	Recover Epicormic buds Epicormic buds are dormant buds under the bark or even deeper. Buds can turn active and grow due to environmental stress such as fire or drought. This trait can help plants to recover their canopies rapidly after a fire. For example, eucalypts are known for this trait. The bark may be removed or burnt by severe fires, but buds are still able to germinate and recover. This trait is common in surface or low-severity fire regimes.
Fire adaptations	Plant adaptations to fire	Lignotubers Not all plants have thick bark and epicormic buds. But for some shrubs and trees, their buds are located below ground, which are able to re-sprout even when the stems are killed by fire. Lignotubers, woody structures around the roots of plants that contains many dormant buds and nutrients such as starch, are very helpful for plants to recover after a fire. In case the stem was damaged by a fire, buds will sprout forming basal shoots. Species with lignotubers are often seen in crown or high-severity fire regimes (e.g., chamise in chaparral).
Fire adaptations	Plant adaptations to fire	Clonal spread Clonal spread is usually triggered by fires and other forms of removal of above-ground stems. The buds from the mother plant can develop into basal shoots or suckers from roots some distance from the plant. Aspen and Californian redwoods are two examples of clonal spread. In clonal communities, all the individuals developed vegetatively from one single ancestor rather than reproduced sexually. For example, the Pando is a large clonal aspen colony in Utah that developed from a single quaking aspen tree. There are currently more than 40,000 trunks in this colony, and the root system is about 80,000 years old.
Fire adaptations	Plant adaptations to fire	Recruit Serotiny Serotiny is a seed dispersal strategy in which the dissemination of seeds is stimulated by external triggers (such as fires) rather than by natural maturation. For serotinous plants, seeds are protected by woody structures during fires and will germinate after the fire. This trait can be found in conifer genera in both the northern and southern hemispheres as well as in flowering plant families (e.g., Banksia). Serotiny is a typical trait in the crown or high-severity fire regimes.
Fire adaptations	Plant adaptations to fire	Fire stimulated germination Many species persist in a long-lived soil seed bank, and are stimulated to germinate via thermal scarification or smoke exposure. Fire-stimulated flowering A less common strategy is fire-stimulated flowering. Dispersal Species with very high wind dispersal capacity and seed production often are the first arrivals after a fire or other soil disturbance. For example, fireweed is common in burned areas in the western United States.
Fire adaptations	Plants and fire regimes	The fire regime exerts a strong filter on which plant species may occur in a given locality. For example, trees in high-severity regimes usually have thin bark while trees in low-severity regimes typically have thick bark. Another example will be that trees in surface fire regimes tend to have epicormic buds rather than basal buds. On the other hand, plants can also alter fire regimes. Oaks, for example, produce a litter layer which slows down the fire spread while pines create a flammable duff layer which increases fire spread. More profoundly, the composition of species can influence fire regimes even when the climate remains unchanged. For example, the mixed forests consists of conifers and chaparral can be found in Cascade Mountains. Conifers burn with low-severity surface fires while chaparral burns with high-severity crown fires. Ironically, some trees can "use" fires to help them to survive during competitions with other trees. Pine trees, for example, can produce flammable litter layers, which help them to take advantage during the completion with other, less fire adapted, species.Grasslands in Western Sabah, Malaysian pine forests, and Indonesian Casuarina forests are believed to have resulted from previous periods of fire. Chamise deadwood litter is low in water content and flammable, and the shrub quickly sprouts after a fire. Cape lilies lie dormant until flames brush away the covering and then blossom almost overnight. Sequoia rely on periodic fires to reduce competition, release seeds from their cones, and clear the soil and canopy for new growth. Caribbean Pine in Bahamian pineyards have adapted to and rely on low-intensity, surface fires for survival and growth. An optimum fire frequency for growth is every 3 to 10 years. Too frequent fires favor herbaceous plants, and infrequent fires favor species typical of Bahamian dry forests.
Fire adaptations	Evolution of fire survival traits	Phylogenetic studies indicated that fire adaptive traits have evolved for a long time (tens of millions of years) and these traits are associated with the environment. In habitats with regular surface fires, similar species developed traits such as thick bark and self-pruning branches. In crown fire regimes, pines have evolved traits such as retaining dead branches in order to attract fires. These traits are inherited from the fire-sensitive ancestors of modern pines. Other traits such as serotiny and fire-stimulating flowering also have evolved for millions of years. Some species are capable of using flammability to establish their habitats. For example, trees evolved with fire-embracing traits can "sacrifice" themselves during fires. But they also cause fires to spread and kill their less flammable neighbors. With the help of other fire adaptive traits such as serotiny, flammable trees will occupy the gap created by fires and colonize the habitat.
Fire adaptations	Animals' adaptations to fires	Direct effects of fires on animals Most animals have sufficient mobility to successfully evade fires. Vertebrates such as large mammals and adult birds are usually capable of escaping from fires. However, young animals which lack mobility may suffer from fires and have high mortality. Ground-dwelling invertebrates are less impacted by fires (due to low thermal diffusivity of soil) while tree-living invertebrates may be killed by crown fires but survive surface fires. Animals are seldom killed by fires directly. Of the animals killed during the Yellowstone fires of 1988, asphyxiation is believed to be the primary cause of death.
Fire adaptations	Animals' adaptations to fires	Long term effects of fires on animals More importantly, fires have long-term effects on the post-burn environment. Fires in seldom-burned rainforests can cause disasters. For example, El Niño-induced surface fires in central Brazilian Amazonia have seriously affected the habitats of birds and primates. Fires also expose animals to dangers such as humans or predators. Generally in a habitat previously with more understory species and less open site species, a fire may replace the fauna structure with more open species and much less understory species. However, the habitat normally will recover to the original structure.
Fire adaptations	Animals and fire regimes	Just like plants may alter fire regimes, animals also have impacts on fire regimes. For example, grazing animals consume fuel for fires and reduce the possibilities of future fires. Many animals play roles as designers of fire regimes. Prairie dogs, for example, are rodents which are common in North America. They are able to control fires by grazing grasses too short to burn.
Fire adaptations	Animal use of fire	Fires are not always detrimental. Burnt areas usually have better quality and accessibility of foods for animals, which attract animals to forage from nearby habitats. For example, fires can kill trees, and dead trees can attract insects. Birds are attracted by the abundance of food, and they can spread the seeds of herbaceous plants. Eventually large herbivores will also flourish. Also, large mammals prefer newly burnt areas because they need less vigilance for predators.An example of animals' uses on fires is the black kite, a carnivorous bird which can be found globally. In monsoonal areas of north Australia, surface fires can spread, including across intended firebreaks, by burning or smoldering pieces of wood or burning tufts of grass carried intentionally by large flying birds accustomed to catch prey flushed out by wildfires. Species involved in this activity are the black kite (Milvus migrans), whistling kite (Haliastur sphenurus), and brown falcon (Falco berigora). Local Aborigines have known of this behavior for a long time, including in their mythology.
Merochlorophaeic acid	Merochlorophaeic acid	Merochlorophaeic acid is a depside with the molecular formula C24H30O8 which has been isolated from the lichen Cladonia merochlorophaea.
Drum stick	Drum stick	A drum stick (or drumstick) is a type of percussion mallet used particularly for playing snare drum, drum kit, and some other percussion instruments, and particularly for playing unpitched percussion. Specialized beaters used on some other percussion instruments, such as the metal beater used with a triangle or the mallets used with tuned percussion (such as xylophone and timpani), are not normally referred to as drumsticks. Drumsticks generally have all of the following characteristics: They are normally supplied and used in pairs. They may be used to play at least some sort of drum (as well as other instruments). They are normally used only for unpitched percussion.
Drum stick	Construction	The archetypical drumstick is turned from a single piece of wood, most commonly of hickory, less commonly of maple, and least commonly but still in significant numbers, of oak. Drumsticks of the traditional form are also made from metal, carbon fibre, and other modern materials. The tip or bead is the part most often used to strike the instrument. Originally and still commonly of the same piece of wood as the rest of the stick, sticks with nylon tips have also been available since 1958. In the 1970s, an acetal tip was introduced. Tips of whatever material are of various shapes, including acorn, barrel, oval, teardrop, pointed and round.
Drum stick	Construction	The shoulder of the stick is the part that tapers towards the tip, and is normally slightly convex. It is often used for playing the bell of a cymbal. It can also be used to produce a cymbal crash when applied with a glancing motion to the bow or edge of a cymbal, and for playing ride patterns on china, swish, and pang cymbals.
Drum stick	Construction	The shaft is the body of the stick, and is cylindrical for most applications including drum kit and orchestral work. It is used for playing cross stick and applied in a glancing motion to the rim of a cymbal for the loudest cymbal crashes. The butt is the opposite end of the stick to the tip. Some rock and metal musicians use it rather than the tip.
Drum stick	Conventional numbering	Plain wooden drumsticks are most commonly described using a number to describe the weight and diameter of the stick followed by one or more letters to describe the tip. For example, a 7A is a common jazz stick with a wooden tip, while a 7AN is the same weight of stick with a nylon tip, and a 7B is a wooden tip but with a different tip profile, shorter and rounder than a 7A. A 5A is a common wood tipped rock stick, heavier than a 7A but with a similar profile. The numbers are most commonly odd but even numbers are used occasionally, in the range 2 (heaviest) to 9 (lightest).
Drum stick	Conventional numbering	The exact meanings of both numbers and letters differ from manufacturer to manufacturer, and some sticks are not described using this system at all, just being known as jazz (typically a 7A, 8A or 8D) or heavy rock (typically a 5B) for example. The most general purpose stick is a 5A. However, there is no one stick for any particular style of music.
Drum stick	Grip	There are two main ways of holding drumsticks: Traditional grip, in which right and left hands use different grips. Matched grip, in which the two hand grips are mirror-image.Traditional grip was developed to conveniently play a snare drum while riding a horse, and was documented by Sanford A. Moeller in The Art of Snare Drumming (1925). It was the standard grip for kit drummers in the first half of the twentieth century and remains popular. Matched grips became popular towards the middle of the twentieth century, threatening to displace the traditional grip for kit drumming. However the traditional grip has since made a comeback, and both types of grip are still used and promoted by leading drummers and teachers.
Drum stick	Popular brands	Pro-Mark Vic Firth Vater Percussion Regal Tip Tama Drums Collision Drumsticks
Inclusive Skating	Inclusive Skating	Inclusive Skating is a charity that provides opportunities for skaters with additional needs. They cater to skaters of all levels, ranging from first-timers to recreational skaters, to elite competitive level athletes and hold events on a global scale which utilise their own judging framework developed for judging skaters who have additional challenges.
Inclusive Skating	Background	Founded in 2011 as Impaired Skating, the charity renamed itself to Inclusive Skating following feedback from its members.Inclusive Skating's main objective is the advancement of public participation in sport and the promotion of equality and diversity and the development and implementation of programming which fosters the inclusion of skaters with any form of impairment or disability. They offer events, competitions, seminars, workshops, and E-Learning resources for its skaters, coaches, parents, and volunteers.The club structure has been officially recognised by the Scottish Parliament, where they are an active member of the Cross-Party Group on Sport.Inclusive skating advocates for the inclusion of skating in the Paralympic Games.
Inclusive Skating	Activities	Since 2021 their courses have been endorsed by CIMSPA and they are also an approved activity provider (AAP) for The Duke of Edinburgh's Award for physical, skills, and volunteering. In 2023 IS became an SQA approved centre with successful candidates eligible to earn UCAS points.
Inclusive Skating	Judging Framework	This Inclusive Skating judging framework is the first in the world for judging sports which takes into account all types of impairments. Currently, the framework facilitates the inclusion of skaters with conditions including physical disability, visual impairment, sensory challenges, autism, cerebral palsy, cystic fibrosis, genetic disorders and mental and behavioural impairments, among others. They also offers the option for skaters to compete via pre-recorded video, to accommodate for conditions which might impede upon an athlete's ability to compete live, such as anxiety.
Inclusive Skating	Events	Inclusive Skating holds educational events, workshops, seminars, and competitions. Competition events are held for all skating disciplines including: singles free-skating, pairs, ice dancing, solo ice dancing, figures, Synchronized skating, speed skating, inline skating, and off-ice competitive events. These competitions utilise the IS judging system which allows for fair competition between skaters with different disabilities using a compensation system based on the empirically researched Dr. Rondinelli Guides to the Evaluation of Permanent Impairment from the American Medical Association.Prince Edward, president of the Sport and Recreation Alliance, was also a guest of honour at the Scottish Championship event in 2019.Inclusive Skating's event format has been adopted by the International Skating Union. In 2022 Inclusive Skating became an institutional partner with the ISU for World Ice Skating Day holding the 2022 Virtual World Championships as part of the global celebration.
Inclusive Skating	Membership	Inclusive Skating is a member of the following organisations: Scottish Sports Association Welsh Sports Association Northern Ireland Sports Forum Sport and Recreation Alliance Scottish Council for Voluntary Organisations Health and Social Care Alliance Scotland
ISO 9	ISO 9	ISO 9 is an international standard establishing a system for the transliteration into Latin characters of Cyrillic characters constituting the alphabets of many Slavic and non-Slavic languages.Published on February 23, 1995 by the International Organization for Standardization, the major advantage ISO 9 has over other competing systems is its univocal system of one character for one character equivalents (by the use of diacritics), which faithfully represents the original spelling and allows for reverse transliteration, even if the language is unknown.
ISO 9	ISO 9	Earlier versions of the standard, ISO/R 9:1954, ISO/R 9:1968 and ISO 9:1986, were more closely based on the international scholarly system for linguistics (scientific transliteration), but have diverged in favour of unambiguous transliteration over phonemic representation. The edition of 1995 supersedes the edition of 1986.
ISO 9	ISO 9:1995	The standard features three mapping tables: the first covers contemporary Slavic languages, the second older Slavic orthographies (excluding letters from the first), and the third non-Slavic languages (including most letters from the first). Several Cyrillic characters included in ISO 9 are not available as pre-composed characters in Unicode, nor are some of the transliterations; combining diacritical marks have to be used in these cases. Unicode, on the other hand, includes some historic characters that are not dealt with in ISO 9.
ISO 9	ISO 9:1995	Transliteration table The following combined table shows characters for various Slavic, Iranian, Romance, Turkic, Uralic, Mongolic, Caucasian, Tungusic, Paleosiberian and other languages of the former USSR which are written in Cyrillic. National adoptions Sample text The following text is a fragment of the Preamble of the Universal Declaration of Human Rights in Bulgarian:
ISO 9	ISO/R 9	ISO Recommendation No. 9, published 1954 and revised 1968, is an older version of the standard, with different transliteration for different Slavic languages, reflecting their phonemic differences. It is closer to the original international system of Slavist scientific transliteration. A German adaptation of this standard was published by the Deutsches Institut für Normung as DIN 1460 (1982) for Slavic languages and supplemented by DIN 1460-2 (2010) for non-Slavic languages. The languages covered are Bulgarian, Russian, Belarusian, Ukrainian, Serbo-Croatian and Macedonian. For comparison, ISO 9:1995 is shown in the table below. Alternative schemes: ISO/R 9:1968 permits some deviations from the main standard. In the table below, they are listed in the columns alternative 1 and alternative 2. The first sub-standard defines some language-dependent transliterations for Belarusian (BE), Bulgarian (BG), Russian (RU), and Ukrainian (UK). The second sub-standard permits, in countries where tradition favours it, a set of alternative transliterations, but only as a group. It is identical to the British Standard 2979:1958 for Cyrillic romanization.
Schur product theorem	Schur product theorem	In mathematics, particularly in linear algebra, the Schur product theorem states that the Hadamard product of two positive definite matrices is also a positive definite matrix.
Schur product theorem	Schur product theorem	The result is named after Issai Schur (Schur 1911, p. 14, Theorem VII) (note that Schur signed as J. Schur in Journal für die reine und angewandte Mathematik.) We remark that the converse of the theorem holds in the following sense. If M is a symmetric matrix and the Hadamard product M∘N is positive definite for all positive definite matrices N , then M itself is positive definite.
Schur product theorem	Proof	Proof using the trace formula For any matrices M and N , the Hadamard product M∘N considered as a bilinear form acts on vectors a,b as tr diag diag ⁡(b)) where tr is the matrix trace and diag ⁡(a) is the diagonal matrix having as diagonal entries the elements of a Suppose M and N are positive definite, and so Hermitian. We can consider their square-roots M12 and N12 , which are also Hermitian, and write tr diag diag tr diag diag tr diag diag ⁡(b)M¯12) Then, for a=b , this is written as tr ⁡(A∗A) for diag ⁡(a)M¯12 and thus is strictly positive for A≠0 , which occurs if and only if a≠0 . This shows that (M∘N) is a positive definite matrix.
Schur product theorem	Proof	Proof using Gaussian integration Case of M = N Let X be an n -dimensional centered Gaussian random variable with covariance ⟨XiXj⟩=Mij . Then the covariance matrix of Xi2 and Xj2 is Cov ⁡(Xi2,Xj2)=⟨Xi2Xj2⟩−⟨Xi2⟩⟨Xj2⟩ Using Wick's theorem to develop ⟨Xi2Xj2⟩=2⟨XiXj⟩2+⟨Xi2⟩⟨Xj2⟩ we have Cov ⁡(Xi2,Xj2)=2⟨XiXj⟩2=2Mij2 Since a covariance matrix is positive definite, this proves that the matrix with elements Mij2 is a positive definite matrix.
Schur product theorem	Proof	General case Let X and Y be n -dimensional centered Gaussian random variables with covariances ⟨XiXj⟩=Mij , ⟨YiYj⟩=Nij and independent from each other so that we have ⟨XiYj⟩=0 for any i,j Then the covariance matrix of XiYi and XjYj is Cov ⁡(XiYi,XjYj)=⟨XiYiXjYj⟩−⟨XiYi⟩⟨XjYj⟩ Using Wick's theorem to develop ⟨XiYiXjYj⟩=⟨XiXj⟩⟨YiYj⟩+⟨XiYi⟩⟨XjYj⟩+⟨XiYj⟩⟨XjYi⟩ and also using the independence of X and Y , we have Cov ⁡(XiYi,XjYj)=⟨XiXj⟩⟨YiYj⟩=MijNij Since a covariance matrix is positive definite, this proves that the matrix with elements MijNij is a positive definite matrix.
Schur product theorem	Proof	Proof using eigendecomposition Proof of positive semidefiniteness Let M=∑μimimiT and N=∑νininiT . Then M∘N=∑ijμiνj(mimiT)∘(njnjT)=∑ijμiνj(mi∘nj)(mi∘nj)T Each (mi∘nj)(mi∘nj)T is positive semidefinite (but, except in the 1-dimensional case, not positive definite, since they are rank 1 matrices). Also, μiνj>0 thus the sum M∘N is also positive semidefinite.
Schur product theorem	Proof	Proof of definiteness To show that the result is positive definite requires even further proof. We shall show that for any vector a≠0 , we have aT(M∘N)a>0 . Continuing as above, each aT(mi∘nj)(mi∘nj)Ta≥0 , so it remains to show that there exist i and j for which corresponding term above is nonzero. For this we observe that aT(mi∘nj)(mi∘nj)Ta=(∑kmi,knj,kak)2 Since N is positive definite, there is a j for which nj∘a≠0 (since otherwise njTa=∑k(nj∘a)k=0 for all j ), and likewise since M is positive definite there exists an i for which 0.
Schur product theorem	Proof	However, this last sum is just ∑kmi,knj,kak . Thus its square is positive. This completes the proof.
Polymer engineering	Polymer engineering	Polymer engineering is generally an engineering field that designs, analyses, and modifies polymer materials. Polymer engineering covers aspects of the petrochemical industry, polymerization, structure and characterization of polymers, properties of polymers, compounding and processing of polymers and description of major polymers, structure property relations and applications.
Polymer engineering	History	The word “polymer” was introduced by the Swedish chemist J. J. Berzelius. He considered, for example, benzene (C6H6) to be a polymer of ethyne (C2H2). Later, this definition underwent a subtle modification.The history of human use of polymers has been long since the mid-19th century, when it entered the chemical modification of natural polymers. In 1839, Charles Goodyear found a critical advance in the research of rubber vulcanization, which has turned natural rubber into a practical engineering material. In 1870, J. W. Hyatt uses camphor to plasticize nitrocellulose to make nitrocellulose plastics industrial. 1907 L. Baekeland reported the synthesis of the first thermosetting phenolic resin, which was industrialized in the 1920s, the first synthetic plastic product. In 1920, H. Standinger proposed that polymers are long-chain molecules that are connected by structural units through common covalent bonds. This conclusion laid the foundation for the establishment of modern polymer science. Subsequently, Carothers divided the synthetic polymers into two broad categories, namely a polycondensate obtained by a polycondensation reaction and an addition polymer obtained by a polyaddition reaction. In the 1950s, K. Ziegler and G. Natta discovered a coordination polymerization catalyst and pioneered the era of synthesis of stereoregular polymers. In the decades after the establishment of the concept of macromolecules, the synthesis of high polymers has achieved rapid development, and many important polymers have been industrialized one after another.
Polymer engineering	Classification	The basic division of polymers into thermoplastics, elastomers and thermosets helps define their areas of application.
Polymer engineering	Classification	Thermoplastics Thermoplastic refers to a plastic that has heat softening and cooling hardening properties. Most of the plastics we use in our daily lives fall into this category. It becomes soft and even flows when heated, and the cooling becomes hard. This process is reversible and can be repeated. Thermoplastics have relatively low tensile moduli, but also have lower densities and properties such as transparency which make them ideal for consumer products and medical products. They include polyethylene, polypropylene, nylon, acetal resin, polycarbonate and PET, all of which are widely used materials.
Polymer engineering	Classification	Elastomers An elastomer generally refers to a material that can be restored to its original state after removal of an external force, whereas a material having elasticity is not necessarily an elastomer. The elastomer is only deformed under weak stress, and the stress can be quickly restored to a polymer material close to the original state and size. Elastomers are polymers which have very low moduli and show reversible extension when strained, a valuable property for vibration absorption and damping. They may either be thermoplastic (in which case they are known as Thermoplastic elastomers) or crosslinked, as in most conventional rubber products such as tyres. Typical rubbers used conventionally include natural rubber, nitrile rubber, polychloroprene, polybutadiene, styrene-butadiene and fluorinated rubbers.
Polymer engineering	Classification	Thermosets A thermosetting resin is used as a main component, and a plastic which forms a product is formed by a cross-linking curing process in combination with various necessary additives. It is liquid in the early stage of the manufacturing or molding process, and it is insoluble and infusible after curing, and it cannot be melted or softened again. Common thermosetting plastics are phenolic plastics, epoxy plastics, aminoplasts, unsaturated polyesters, alkyd plastics, and the like. Thermoset plastics and thermoplastics together constitute the two major components of synthetic plastics. Thermosetting plastics are divided into two types: formaldehyde cross-linking type and other cross-linking type.
Polymer engineering	Classification	Thermosets includes phenolic resins, polyesters and epoxy resins, all of which are used widely in composite materials when reinforced with stiff fibers such as fiberglass and aramids. Since crosslinking stabilises the thermoset polymer matrix of these materials, they have physical properties more similar to traditional engineering materials like steel. However, their very much lower densities compared with metals makes them ideal for lightweight structures. In addition, they suffer less from fatigue, so are ideal for safety-critical parts which are stressed regularly in service.
Polymer engineering	Materials	Plastic Plastic is a polymer compound which is polymerized by polyaddition polymerization and polycondensation. It is free to change the composition and shape. It is made up of synthetic resins and fillers, plasticizers, stabilizers, lubricants, colorants and other additives. The main component of plastic is resin. Resin means that the polymer compound has not been added with various additives. The term resin was originally named for the secretion of oil from plants and animals, such as rosin and shellac. Resin accounts for approximately 40% - 100% of the total weight of the plastic. The basic properties of plastics are mainly determined by the nature of the resin, but additives also play an important role. Some plastics are basically made of synthetic resins, with or without additives such as plexiglass, polystyrene, etc.
Polymer engineering	Materials	Fiber Fiber refers to a continuous or discontinuous filament of one substance. Animals and plant fibers play an important role in maintaining tissue. Fibers are widely used and can be woven into good threads, thread ends and hemp ropes. They can also be woven into fibrous layers when making paper or feel. They are also commonly used to make other materials together with other materials to form composites. Therefore, whether it is natural or synthetic fiber filamentous material. In modern life, the application of fiber is ubiquitous, and there are many high-tech products.
Polymer engineering	Materials	Rubber Rubber refers to highly elastic polymer materials and reversible shapes. It is elastic at room temperature and can be deformed with a small external force. After removing the external force, it can return to the original state. Rubber is a completely amorphous polymer with a low glass transition temperature and a large molecular weight, often greater than several hundred thousand. Highly elastic polymer compounds can be classified into natural rubber and synthetic rubber. Natural rubber processing extracts gum rubber and grass rubber from plants; synthetic rubber is polymerized by various monomers. Rubber can be used as elastic, insulating, water-impermeable air-resistant materials.
Polymer engineering	Applications	Polyethylene Commonly used polyethylenes can be classified into low density polyethylene (LDPE), high density polyethylene (HDPE), and linear low density polyethylene (LLDPE). Among them, HDPE has better thermal, electrical and mechanical properties, while LDPE and LLDPE have better flexibility, impact properties and film forming properties. LDPE and LLDPE are mainly used for plastic bags, plastic wraps, bottles, pipes and containers; HDPE is widely used in various fields such as film, pipelines and daily necessities because its resistance to many different solvents.
Polymer engineering	Applications	Polypropylene Polypropylene is widely used in various applications due to its good chemical resistance and weldability. It has lowest density among commodity plastics. It is commonly used in packaging applications, consumer goods, automatic applications and medical applications. Polypropylene sheets are widely used in industrial sector to produce acid and chemical tanks, sheets, pipes, Returnable Transport Packaging (RTP), etc. because of its properties like high tensile strength, resistance to high temperatures and corrosion resistance.
Polymer engineering	Applications	Composites Typical uses of composites are monocoque structures for aerospace and automobiles, as well as more mundane products like fishing rods and bicycles. The stealth bomber was the first all-composite aircraft, but many passenger aircraft like the Airbus and the Boeing 787 use an increasing proportion of composites in their fuselages, such as hydrophobic melamine foam. The quite different physical properties of composites gives designers much greater freedom in shaping parts, which is why composite products often look different from conventional products. On the other hand, some products such as drive shafts, helicopter rotor blades, and propellers look identical to metal precursors owing to the basic functional needs of such components.
Polymer engineering	Applications	Biomedical applications Biodegradable polymers are widely used materials for many biomedical and pharmaceutical applications. These polymers are considered very promising for controlled drug delivery devices. Biodegradable polymers also offer great potential for wound management, orthopaedic devices, dental applications and tissue engineering. Not like non biodegradable polymers, they won't require a second step of a removal from body. Biodegradable polymers will break down and are absorbed by the body after they served their purpose. Since 1960, polymers prepared from glycolic acid and lactic acid have found a multitude of uses in the medical industry. Polylactates (PLAs) are popular for drug delivery system due to their fast and adjustable degradation rate.
Polymer engineering	Applications	Membrane technologies Membrane techniques are successfully used in the separation in the liquid and gas systems for years, and the polymeric membranes are used most commonly because they have lower cost to produce and are easy to modify their surface, which make them suitable in different separation processes. Polymers helps in many fields including the application for separation of biological active compounds, proton exchange membranes for fuel cells and membrane contractors for carbon dioxide capture process.
Polymer engineering	Related Major	Petroleum / Chemical / Mineral / Geology Raw materials and processing New energy Automobiles and spare parts Other industries Electronic Technology / Semiconductor / Integrated Circuit Machinery / Equipment / Heavy Industry Medical equipment / instruments
Natural Language and Linguistic Theory	Natural Language and Linguistic Theory	Natural Language & Linguistic Theory is a quarterly peer-reviewed academic journal covering theoretical and generative linguistics. It was established in 1983 and originally published by Kluwer Academic Publishers. Since 2004 the journal is published by Springer Science+Business Media. The editor-in-chief is Julie Anne Legate (University of Pennsylvania). The journal carries a "Topic-Comment" column (initiated by Geoffrey K. Pullum), in which a contributor presents a personal, sometimes controversial, opinion on some aspect of the field.
Natural Language and Linguistic Theory	Abstracting and indexing	The journal is abstracted and indexed in: According to the Journal Citation Reports, the journal has a 2015 impact factor of 0.845.
Stook	Stook	A stook /stʊk/, also referred to as a shock or stack, is an arrangement of sheaves of cut grain-stalks placed so as to keep the grain-heads off the ground while still in the field and before collection for threshing. Stooked grain sheaves are typically wheat, barley and oats. In the era before combine harvesters and powered grain driers, stooking was necessary to dry the grain for a period of days to weeks before threshing, to achieve a moisture level low enough for storage. In the 21st century, most grain is produced with the mechanized and powered methods, and is therefore not stooked at all. However, stooking remains useful to smallholders who grow their own grain, or at least some of it, as opposed to buying it.
Stook	Overview	The purpose of a stook [or 'stooking'] is to dry the unthreshed grain while protecting it from vermin until it is brought into long-term storage. The unthreshed grain also cures while in a stook. In England, sheaves were commonly stacked in stooks of twelve and may therefore refer to twelve sheaves.
Stook	Overview	Stook may also have a general meaning of 'bundle' or 'heap' and applicable to items other than sheaves or bales. For example, in the era when traditional hay-making was common, raked-up piles of hay were also called stooks, shocks, or ricks. Today baling has largely replaced the stook method of drying hay, or hay is chopped and ensilaged either in silos or on the ground inside polymer wrappers to make haylage.
Stook	Overview	In North America, a stook may also refer to a field stack of six, ten or fifteen small (70–90 lb (30–40 kg)), rectangular bales of hay or straw. These bales may be stacked and deposited by a "stooking machine" or "stooker" that is dragged, sled-like, behind the baler. The stooking sled has four, five, or six fingers that hold the bales until the stook is complete. When the stook is complete the "stacker" steps on a lever to release the stook. The fingers drop to the ground and the finished stook slides off the fingers. The sled resets itself and is ready to be filled again. The bales are stacked on the diagonal to shed the rain and to minimise acquiring moisture from the ground before being picked up. An automatic bale stooker was eventually designed to eliminate the need for a person to manually stack and trip the stook-release. The automatic stooker is positioned behind the baler and collects released bales and sends them up an inclined shute. The bale falls through a series of bars into the "3-2-1" configuration. Once all six bales are in position the platform trips, drops the stook in the field, and automatically returns to the loading position. Allied produced a model of stooker in the 1980s that can still be found across the countryside in Canada today.
Stook	Shocking or stooking	Before mechanical harvesting became the norm, a common agricultural practice was to manually cut sheaves of grain, tie them in bundles, and stack them against one another vertically to form a "shock" so that they could air dry. In the era before combine harvesters and powered grain driers, stooking was necessary to dry the grain for a period of days to weeks before threshing, to achieve a moisture level low enough for storage. In the 21st century, most grain is produced with the mechanized and powered methods, and is therefore not stocked at all. However, stooking remains useful to smallholders who grow their own grain, or at least some of it, as opposed to buying it.
Maxwell Montes	Maxwell Montes	Maxwell Montes is a mountain massif on the planet Venus, of which Skadi Mons is the highest point on the planet's surface.

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