document_title: Money bill

question_text: who is to certify that any bill is a money bill

text: Money bill

text: Conventions[edit]

text: It is often a constitutional convention that the upper house may not block a money bill. There is often another requirement that non-money bill-type clauses may not be attached to a money bill. The rationale behind this convention is that the upper house, being appointed or indirectly elected, should not have any right to decide on taxation and public expenditure-related policies as may be framed by the directly elected representatives of the lower house. Therefore, money bills are an exception to the general rule that for a bill to be enacted into a law, it has to be approved by both Houses of the Parliament—the lower house and the upper house.[1]

text: Loss of supply in the lower house is conventionally considered to be an expression of the house's loss of confidence in the government resulting in the government's fall.

text: Requirements in Westminster systems[edit]

text: Australia[edit]

text: A supply bill in the Australian System is required to pass the House of Representatives, the Senate and be signed by the Governor-General. The Senate has no power or ability to introduce or modify a supply bill, but has the ability to block or defer the passing of a supply bill. The most famous instance where supply was blocked was during the 1975 constitutional crisis. This has resulted in agreements between political parties to prevent the blockage of supply bills through the Senate.

text: Bangladesh[edit]

text: A money bill is specifically defined by Article 81 of the Constitution of Bangladesh. The President of Bangladesh can send back all bills passed by the Parliament for a review except a money bill. However, a money bill can be introduced to the Parliament only at the President's recommendation. Additionally, tax can only be levied by the Parliament.[2]

text: India[edit]

text: Procedure for a Money Bill:

text:
Money Bills can be introduced only in Lok Sabha (the directly elected 'people's house' of the Indian Parliament).
Money bills passed by the Lok Sabha are sent to the Rajya Sabha (the upper house of parliament, elected by the state and territorial legislatures or appointed by the president). The Rajya Sabha may not amend money bills but can recommend amendments. To make sure that Rajya Sabha doesn't amend the bill by adding some non-money matters (known as Financial Bill), the Speaker of the Lok Sabha certifies the bill as a money bill before sending it to the upper house, and the decision of the Speaker is binding on both the Houses.[3] A money bill must be returned to the Lok Sabha within 14 days, or the bill is deemed to have passed both houses in the form it was originally passed by the Lok Sabha.
When a Money Bill is returned to the Lok Sabha with the recommended amendments of the Rajya Sabha, it is open to the Lok Sabha to accept or reject any or all of the recommendations.
A money bill is deemed to have passed both houses with any recommended amendments the Lok Sabha chooses to accept, and without any that it chooses to decline.
The definition of "Money Bill" is given in Article 110 of the Constitution of India. A financial bill is not a Money Bill unless it fulfills the requirements of Article 110.
The Speaker of the Lok Sabha certifies if a financial bill is a Money Bill or not.[4]
Policy cut motion - disapproval of the given policy. Symbolically, the members demand that the amount of the demand be reduced to 1 INR. They may also suggest an alternative policy.
Economy cut motion - it is demanded that the amount of the policy be reduced by a specified amount.
Token cut motion - used to show specific grievance against the government. Also states that the amount of the demand be reduced by Rs. 100.
A money bill can only be introduced in parliament with prior permission of the President of India.
Finance bill is supposed to be enacted within 75 days (including the Parliament voting and the President assenting).
Money bill cannot be returned by the President to the parliament for its reconsideration, as it is presented in the Lok Sabha with his permission.

tag: ol

text: The concept of money bills in India came to the forefront during the enactment of the Aadhar Act, 2016. In spite of resistance by the opposition, the Aadhaar Bill was certified as a ‘money bill’ by the Speaker of the Lower House. The Upper House proposed certain amendments, but ultimately the BJP-dominated Lower House rejected the amendments suggested by the Upper House and unilaterally enacted the Aadhar Act, 2016. Immediately thereafter, Jairam Ramesh, a senior Congress leader, challenged the speaker’s decision to treat the Aadhar Bill as a ‘money bill’ before the Supreme Court of India. Article 110(3) of the Constitution of India categorically states that 'if any question arises whether a Bill is a Money Bill or not, the decision of the Speaker of the House of the People thereon shall be final'. Therefore, one of the prime constitutional questions before the Supreme Court is whether it can review the speaker’s certificate classifying a bill as a ‘money bill’. In three prior cases, the Supreme Court of India has refused to review the Speaker's certificate. However, some commentators have argued that the Court's earlier judgements were incorrect and Article 110(3) made the Speaker’s decision "final" for the purpose of the two Houses of the Parliament, not for the Supreme Court of India.[5] This argument is further supported by the fact that in Kihoto Hollohan vs Zachillhu (AIR 1993 SC 412), the "final" decision of the speaker regarding disqualification of members of the House under the Tenth Schedule of the Indian Constitution was held to be a judicial decision subject to judicial review. This suggests that the "final" status given by the Indian constitution does not automatically immune the Indian speaker's decision or certificate from judicial review.[6] In view of this crucial constitutional question, it has been suggested that the Supreme Court in Jairam Ramesh v. Union of India should create a constitution bench of at least nine judges to settle the law on this issue.[7]

text: Republic of Ireland[edit]

text: In the Republic of Ireland, the Senate may not delay a money bill (Irish: bille airgid)[8] more than 21 days. The President of Ireland may not refuse to sign a money bill and may not refer such a bill to the Supreme Court to test its constitutionality. Procedures exist for resolution of disputes as to whether a Bill is a money bill. Since the 1922 constitution (as amended by the Constitution (Amendment No. 12) Act 1930) and under the 1937 constitution, such disputes can be resolved by a committee on privileges.

text: United Kingdom[edit]

text: In the United Kingdom, section 1(1) of the Parliament Act 1911 provides that the House of Lords may not delay a money bill more than a month. It is at the discretion of the Speaker of the House of Commons to certify which bills are money bills, and his decision is final and is not subject to challenge. Section 1(2) of the Act states:

text: A Money Bill means a Public Bill which in the opinion of the Speaker of the House of Commons contains only provisions dealing with all or any of the following subjects, namely, the imposition, repeal, remission, alteration, or regulation of taxation; the imposition for the payment of debt or other financial purposes of charges on the Consolidated Fund, the National Loans Fund or on money provided by Parliament, or the variation or repeal of any such charges; supply; the appropriation, receipt, custody, issue or audit of accounts of public money; the raising or guarantee of any loan or the repayment thereof; or subordinate matters incidental to those subjects or any of them. In this subsection the expressions "taxation," "public money," and "loan" respectively do not include any taxation, money, or loan raised by local authorities or bodies for local purposes.[9]

text: The Parliament Act 1911 was the product of the political crisis of 1909. The People's Budget of 1909 proposed by the House of Commons was rejected by the House of Lords. A government whose budget (that is the Finance Bill) is rejected can only resign or dissolve Parliament, because without money it is impossible to govern. The rejection of the Finance Bill in 1909 by the Lords prompted the then British government to initiate steps to curtail the powers of the House of Lords in this regard. This is evident from the Preamble of the 1911 Act which states: "An Act to make provision with respect to the powers of the House of Lords in relation to those of the House of Commons ...".[10]

text: The reference to the National Loans Fund was inserted on 1 April 1968[11] by section 1(5) of the National Loans Act 1968.

text: For this purpose, the expression "Public Bill" does not include any Bill for confirming a Provisional Order.

text: Bradley and Ewing said that the statutory definition of Money Bill is "strictly interpreted".[12] Most annual Finance Bills have not been certified to be Money Bills.[13][14][15]

text: Requirements in non-Westminster systems[edit]

text: United States[edit]

text: While the United States of America is not a parliamentary democracy, the Origination Clause of the U.S. Constitution requires that all bills raising revenue originate in the House of Representatives, consistent with British constitutional practice; by convention, appropriation bills (bills that spend money) also originate in the House. Unlike in most Westminster systems, there are no limits on the Senate's ability to amend revenue bills or any requirement for the Senate to approve such bills within a certain timeframe. Both appropriations and revenue bills are often referred to as money bills to contrast them with authorization bills. The U.S. Supreme Court in United States v. Munoz-Flores (1990) held that: "A law passed in violation of the Origination Clause would thus be no more immune from judicial scrutiny because it was passed by both Houses and signed by the President than would be a law passed in violation of the First Amendment".[16]


document_title: Neutron star

question_text: a spinning neutron star that appears to give off radio waves is called a

root

text: Neutron star

text: Formation[edit]

text: Any main-sequence star with an initial mass of above 8 times the mass of the sun (8 M☉) has the potential to produce a neutron star. As the star evolves away from the main sequence, subsequent nuclear burning produces an iron-rich core. When all nuclear fuel in the core has been exhausted, the core must be supported by degeneracy pressure alone. Further deposits of mass from shell burning cause the core to exceed the Chandrasekhar limit. Electron-degeneracy pressure is overcome and the core collapses further, sending temperatures soaring to over 7009500000000000000♠5×109 K. At these temperatures, photodisintegration (the breaking up of iron nuclei into alpha particles by high-energy gamma rays) occurs. As the temperature climbs even higher, electrons and protons combine to form neutrons via electron capture, releasing a flood of neutrinos. When densities reach nuclear density of 7017400000000000000♠4×1017 kg/m3, neutron degeneracy pressure halts the contraction. The infalling outer envelope of the star is halted and flung outwards by a flux of neutrinos produced in the creation of the neutrons, becoming a supernova. The remnant left is a neutron star. If the remnant has a mass greater than about 3 M☉, it collapses further to become a black hole.[13]

tag: p

text: As the core of a massive star is compressed during a Type II supernova, Type Ib or Type Ic supernova, and collapses into a neutron star, it retains most of its angular momentum. But, because it has only a tiny fraction of its parent's radius (and therefore its moment of inertia is sharply reduced), a neutron star is formed with very high rotation speed, and then over a very long period it slows. Neutron stars are known that have rotation periods from about 1.4 ms to 30 s. The neutron star's density also gives it very high surface gravity, with typical values ranging from 1012 to 1013 m/s2 (more than 1011 times that of Earth).[5] One measure of such immense gravity is the fact that neutron stars have an escape velocity ranging from 100,000 km/s to 150,000 km/s, that is, from a third to half the speed of light. The neutron star's gravity accelerates infalling matter to tremendous speed. The force of its impact would likely destroy the object's component atoms, rendering all the matter identical, in most respects, to the rest of the neutron star.

text: Properties[edit]

text: Mass and temperature[edit]

text: A neutron star has a mass of at least 1.1 and perhaps up to 3 solar masses (M☉).[14][15] The maximum observed mass of neutron stars is about 2.01 M☉. But in general, compact stars of less than 1.39 M☉ (the Chandrasekhar limit) are white dwarfs, whereas compact stars with a mass between 1.4 M☉ and 3 M☉ (the Tolman–Oppenheimer–Volkoff limit) should be neutron stars (though there is an interval of a few tenths of a solar mass where the masses of low-mass neutron stars and high-mass white dwarfs can overlap). Between 3 M☉ and 5 M☉, hypothetical intermediate-mass stars such as quark stars and electroweak stars have been proposed, but none have been shown to exist. Beyond 10 M☉ the stellar remnant will overcome the neutron degeneracy pressure and gravitational collapse will usually occur to produce a black hole, though the smallest observed mass of a stellar black hole is about 5 M☉.[16]

text: The temperature inside a newly formed neutron star is from around 1011 to 1012 kelvin.[17] However, the huge number of neutrinos it emits carry away so much energy that the temperature of an isolated neutron star falls within a few years to around 106 kelvin.[17] At this lower temperature, most of the light generated by a neutron star is in X-rays.

text: Density and pressure[edit]

text: Neutron stars have overall densities of 7017370000000000000♠3.7×1017 to 7017590000000000000♠5.9×1017 kg/m3 (7014260000000000000♠2.6×1014 to 7014409999999999999♠4.1×1014 times the density of the Sun),[b] which is comparable to the approximate density of an atomic nucleus of 7017300000000000000♠3×1017 kg/m3.[18] The neutron star's density varies from about 7009100000000000000♠1×109 kg/m3 in the crust—increasing with depth—to about 7017600000000000000♠6×1017 or 7017800000000000000♠8×1017 kg/m3 (denser than an atomic nucleus) deeper inside.[17] A neutron star is so dense that one teaspoon (5 milliliters) of its material would have a mass over 7012550000000000000♠5.5×1012 kg (that is 1100 tonnes per 1 nanolitre), about 900 times the mass of the Great Pyramid of Giza. In the enormous gravitational field of a neutron star, its weight would be 7025110000000000000♠1.1×1025 N, which is about 15 times the weight of the Moon.[c] The pressure increases from 7031320000000000000♠3.2×1031 to 7034159999999999999♠1.6×1034 Pa from the inner crust to the center.[19]

text: The equation of state of matter at such high densities is not precisely known because of the theoretical difficulties associated with extrapolating the likely behavior of quantum chromodynamics, superconductivity, and superfluidity of matter in such states along with the empirical difficulties of observing the characteristics of neutron stars that are at least hundreds of parsecs away.

text: A neutron star has some of the properties of an atomic nucleus, including density (within an order of magnitude) and being composed of nucleons. In popular scientific writing, neutron stars are therefore sometimes described as "giant nuclei". However, in other respects, neutron stars and atomic nuclei are quite different. A nucleus is held together by the strong interaction, whereas a neutron star is held together by gravity. The density of nucleus is uniform, while neutron stars are predicted to consist of multiple layers with varying composition and density.

text: Magnetic field[edit]

text: Neutron stars have strong magnetic fields. The magnetic field strength on the surface of neutron stars has been estimated at least to have the range of 104 to 1011 tesla.[20] In comparison, the magnitude at Earth's surface ranges from 25 to 65 microteslas (0.25 to 0.65 gauss),[21] making the field at least 108 times as strong as that of Earth. For comparison, 16 T is sufficient to levitate a live frog due to diamagnetic levitation. Variations in magnetic field strengths are most likely the main factor that allows different types of neutron stars to be distinguished by their spectra, and explains the periodicity of pulsars.[20] The neutron stars known as magnetars have the strongest magnetic fields, in the range of 108 to 1011 tesla,[22] and have become the widely accepted hypothesis for neutron star types soft gamma repeaters (SGRs)[23] and anomalous X-ray pulsars (AXPs).[24] Fields of this strength are able to polarize the vacuum to the point that the vacuum becomes birefringent. Photons can merge or split in two, and virtual particle-antiparticle pairs are produced. The field changes electron energy levels and atoms are forced into thin cylinders.[25]

text: The origins of the strong magnetic field are as yet unclear.[20] One hypothesis is that of "flux freezing", or conservation of the original magnetic flux takes place during the formation of the neutron star.[20] If an object has a certain magnetic flux over its surface area, and that area shrinks to a smaller area, but the magnetic flux is conserved, then the magnetic field would correspondingly increase. Likewise, a collapsing star begins with a much larger surface area than the resulting neutron star, and conservation of magnetic flux would result in a far stronger magnetic field. However, this simple explanation does not fully explain magnetic field strengths of neutron stars.[20]

text: Gravity and equation of state[edit]

text: The gravitational field at a neutron star's surface is about 7011200000000000000♠2×1011 times stronger than on Earth, at around 7012200000000000000♠2.0×1012 m/s2.[27] Such a strong gravitational field acts as a gravitational lens and bends the radiation emitted by the neutron star such that parts of the normally invisible rear surface become visible.[26] If the radius of the neutron star is 3GM/c2 or less, then the photons may be trapped in an orbit, thus making the whole surface of that neutron star visible from a single vantage point, along with destabilizing photon orbits at or below the 1 radius distance of the star.

text: A fraction of the mass of a star that collapses to form a neutron star is released in the supernova explosion from which it forms (from the law of mass–energy equivalence, E = mc2). The energy comes from the gravitational binding energy of a neutron star.

text: Hence, the gravitational force of a typical neutron star is huge. If an object were to fall from a height of one meter on a neutron star 12 kilometers in radius, it would reach the ground at around 1400 kilometers per second.[28] However, even before impact, the tidal force would cause spaghettification, breaking any sort of an ordinary object into a stream of material.

text: Because of the enormous gravity, time dilation between a neutron star and Earth is significant. For example, eight years could pass on the surface of a neutron star, yet ten years would have passed on Earth, not including the time-dilation effect of its very rapid rotation.[29]

text: Neutron star relativistic equations of state describe the relation of radius vs. mass for various models.[30] The most likely radii for a given neutron star mass are bracketed by models AP4 (smallest radius) and MS2 (largest radius). BE is the ratio of gravitational binding energy mass equivalent to the observed neutron star gravitational mass of "M" kilograms with radius "R" meters,[31]

text: Given current values

text: and star masses "M" commonly reported as multiples of one solar mass,

text: then the relativistic fractional binding energy of a neutron star is

text: A 2 M☉ neutron star would not be more compact than 10,970 meters radius (AP4 model). Its mass fraction gravitational binding energy would then be 0.187, −18.7% (exothermic). This is not near 0.6/2 = 0.3, −30%.

text: The equation of state for a neutron star is still not known. It is assumed that it differs significantly from that of a white dwarf, whose equation of state is that of a degenerate gas that can be described in close agreement with special relativity. However, with a neutron star the increased effects of general relativity can no longer be ignored. Several equations of state have been proposed (FPS, UU, APR, L, SLy, and others) and current research is still attempting to constrain the theories to make predictions of neutron star matter.[5][33] This means that the relation between density and mass is not fully known, and this causes uncertainties in radius estimates. For example, a 1.5 M☉ neutron star could have a radius of 10.7, 11.1, 12.1 or 15.1 kilometers (for EOS FPS, UU, APR or L respectively).[33]

text: Structure[edit]

text: Current understanding of the structure of neutron stars is defined by existing mathematical models, but it might be possible to infer some details through studies of neutron-star oscillations. Asteroseismology, a study applied to ordinary stars, can reveal the inner structure of neutron stars by analyzing observed spectra of stellar oscillations.[5]

text: Current models indicate that matter at the surface of a neutron star is composed of ordinary atomic nuclei crushed into a solid lattice with a sea of electrons flowing through the gaps between them. It is possible that the nuclei at the surface are iron, due to iron's high binding energy per nucleon.[34] It is also possible that heavy elements, such as iron, simply sink beneath the surface, leaving only light nuclei like helium and hydrogen.[34] If the surface temperature exceeds 106 kelvin (as in the case of a young pulsar), the surface should be fluid instead of the solid phase that might exist in cooler neutron stars (temperature <106 kelvin).[34]

text: The "atmosphere" of a neutron star is hypothesized to be at most several micrometers thick, and its dynamics are fully controlled by the neutron star's magnetic field. Below the atmosphere one encounters a solid "crust". This crust is extremely hard and very smooth (with maximum surface irregularities of ~5 mm), due to the extreme gravitational field.[35]

text: Proceeding inward, one encounters nuclei with ever-increasing numbers of neutrons; such nuclei would decay quickly on Earth, but are kept stable by tremendous pressures. As this process continues at increasing depths, the neutron drip becomes overwhelming, and the concentration of free neutrons increases rapidly. In that region, there are nuclei, free electrons, and free neutrons. The nuclei become increasingly small (gravity and pressure overwhelming the strong force) until the core is reached, by definition the point where mostly neutrons exist. The expected hierarchy of phases of nuclear matter in the inner crust has been characterized as "nuclear pasta", with fewer voids and larger structures towards higher pressures.[36] The composition of the superdense matter in the core remains uncertain. One model describes the core as superfluid neutron-degenerate matter (mostly neutrons, with some protons and electrons). More exotic forms of matter are possible, including degenerate strange matter (containing strange quarks in addition to up and down quarks), matter containing high-energy pions and kaons in addition to neutrons,[5] or ultra-dense quark-degenerate matter.

text: Radiation[edit]

text: Pulsars[edit]

text: Neutron stars are detected from their electromagnetic radiation. Neutron stars are usually observed to pulse radio waves and other electromagnetic radiation, and neutron stars observed with pulses are called pulsars.

text: Pulsars' radiation is thought to be caused by particle acceleration near their magnetic poles, which need not be aligned with the rotational axis of the neutron star. It is thought that a large electrostatic field builds up near the magnetic poles, leading to electron emission.[37] These electrons are magnetically accelerated along the field lines, leading to curvature radiation, with the radiation being strongly polarized towards the plane of curvature.[37] In addition, high energy photons can interact with lower energy photons and the magnetic field for electron-positron pair production, which through electron–positron annihilation leads to further high energy photons.[37]

text: The radiation emanating from the magnetic poles of neutron stars can be described as magnetospheric radiation, in reference to the magnetosphere of the neutron star.[38] It is not to be confused with magnetic dipole radiation, which is emitted because the magnetic axis is not aligned with the rotational axis, with a radiation frequency the same as the neutron star's rotational frequency.[37]

text: If the axis of rotation of the neutron star is different to the magnetic axis, external viewers will only see these beams of radiation whenever the magnetic axis point towards them during the neutron star rotation. Therefore, periodic pulses are observed, at the same rate as the rotation of the neutron star.

text: Non-pulsating neutron stars[edit]

text: In addition to pulsars, neutron stars have also been identified with no apparent periodicity of their radiation.[39] This seems to be a characteristic of the X-ray sources known as Central Compact Objects in Supernova remnants (CCOs in SNRs), which are thought to be young, radio-quiet isolated neutron stars.[40]

text: Spectra[edit]

text: In addition to radio emissions, neutron stars have also been identified in other parts of the electromagnetic spectrum. This includes visible light, near infrared, ultraviolet, X-rays and gamma rays.[38] Pulsars observed in X-rays are known as X-ray pulsars if accretion-powered; while those identified in visible light as optical pulsars. The majority of neutron stars detected, including those identified in optical, X-ray and gamma rays, also emit radio waves;[41] the Crab Pulsar produces electromagnetic emissions across the spectrum.[41] However, there exist neutron stars called radio-quiet neutron stars, with no radio emissions detected.[42]

text: Rotation[edit]

text: Neutron stars rotate extremely rapidly after their formation due to the conservation of angular momentum; like spinning ice skaters pulling in their arms, the slow rotation of the original star's core speeds up as it shrinks. A newborn neutron star can rotate many times a second.

text: Spin down[edit]

text: Over time, neutron stars slow, as their rotating magnetic fields in effect radiate energy associated with the rotation; older neutron stars may take several seconds for each revolution. This is called spin down. The rate at which a neutron star slows its rotation is usually constant and very small.

text:
The periodic time (P) is the rotational period, the time for one rotation of a neutron star. The spin-down rate, the rate of slowing of rotation, is then given the symbol

P
˙

{\displaystyle {\dot {P}}}

 (P-dot), the negative derivative of P with respect to time. It is defined as periodic time decrease per unit time; it is a dimensionless quantity, but can be given the units of s⋅s−1 (seconds per second).[37]

text: The spin-down rate (P-dot) of neutron stars usually falls within the range of 10−22 to 10−9 s⋅s−1, with the shorter period (or faster rotating) observable neutron stars usually having smaller P-dot. However, as a neutron star ages, the neutron star slows (P increases) and the rate of slowing decreases (P-dot decreases). Eventually, the rate of rotation becomes too slow to power the radio-emission mechanism, and the neutron star can no longer be detected.[37]

text: P and P-dot allow minimum magnetic fields of neutron stars to be estimated.[37] P and P-dot can be also used to calculate the characteristic age of a pulsar, but gives an estimate which is somewhat larger than the true age when it is applied to young pulsars.[37]

text:
P and P-dot can also be combined with neutron star's moment of inertia to estimate a quantity called spin-down luminosity, which is given the symbol

E
˙

{\displaystyle {\dot {E}}}

 (E-dot). It is not the measured luminosity, but rather the calculated loss rate of rotational energy that would manifest itself as radiation. For neutron stars where the spin-down luminosity is comparable to the actual luminosity, the neutron stars are said to be "rotation powered".[37][38] The observed luminosity of the Crab Pulsar is comparable to the spin-down luminosity, supporting the model that rotational kinetic energy powers the radiation from it.[37] With neutron stars such as magnetars, where the actual luminosity exceeds the spin-down luminosity by about a factor of one hundred, it is assumed that the luminosity is powered by magnetic dissipation, rather than being rotation powered.[43]

text: P and P-dot can also be plotted for neutron stars to create a P–P-dot diagram. It encodes a tremendous amount of information about the pulsar population and its properties, and has been likened to the Hertzsprung–Russell diagram in its importance for neutron stars.[37]

text: Spin up[edit]

text: Neutron star rotational speeds can increase, a process known as spin up. Sometimes neutron stars absorb orbiting matter from companion stars, increasing the rotation rate and reshaping the neutron star into an oblate spheroid. This causes an increase in the rate of rotation of the neutron star of over a hundred times per second in the case of millisecond pulsars.

text: The most rapidly rotating neutron star currently known, PSR J1748-2446ad, rotates at 716 revolutions per second.[44] However, a 2007 paper reported the detection of an X-ray burst oscillation, which provides an indirect measure of spin, of 1122 Hz from the neutron star XTE J1739-285,[45] suggesting 1122 rotations a second. However, at present, this signal has only been seen once, and should be regarded as tentative until confirmed in another burst from that star.

text: Glitches and starquakes[edit]

text: Sometimes a neutron star will undergo a glitch, a sudden small increase of its rotational speed or spin up. Glitches are thought to be the effect of a starquake—as the rotation of the neutron star slows, its shape becomes more spherical. Due to the stiffness of the "neutron" crust, this happens as discrete events when the crust ruptures, creating a starquake similar to earthquakes. After the starquake, the star will have a smaller equatorial radius, and because angular momentum is conserved, its rotational speed has increased.

text: Starquakes occurring in magnetars, with a resulting glitch, is the leading hypothesis for the gamma-ray sources known as soft gamma repeaters.[46]

text: Recent work, however, suggests that a starquake would not release sufficient energy for a neutron star glitch; it has been suggested that glitches may instead be caused by transitions of vortices in the theoretical superfluid core of the neutron star from one metastable energy state to a lower one, thereby releasing energy that appears as an increase in the rotation rate.[47]

text: "Anti-glitches"[edit]

text: An "anti-glitch", a sudden small decrease in rotational speed, or spin down, of a neutron star has also been reported.[48] It occurred in a magnetar, that in one case produced an X-ray luminosity increase of a factor of 20, and a significant spin-down rate change. Current neutron star models do not predict this behavior. If the cause was internal, it suggests differential rotation of solid outer crust and the superfluid component of the magnetar's inner structure.[48]

text: Population and distances[edit]

text: At present, there are about 2000 known neutron stars in the Milky Way and the Magellanic Clouds, the majority of which have been detected as radio pulsars. Neutron stars are mostly concentrated along the disk of the Milky Way although the spread perpendicular to the disk is large because the supernova explosion process can impart high translational speeds (400 km/s) to the newly formed neutron star.

text: Some of the closest known neutron stars are RX J1856.5-3754, which is about 400 light years away, and PSR J0108-1431 at about 424 light years.[50] RX J1856.5-3754 is a member of a close group of neutron stars called The Magnificent Seven. Another nearby neutron star that was detected transiting the backdrop of the constellation Ursa Minor has been nicknamed Calvera by its Canadian and American discoverers, after the villain in the 1960 film The Magnificent Seven. This rapidly moving object was discovered using the ROSAT/Bright Source Catalog.

text: Binary neutron star systems[edit]

text: About 5% of all known neutron stars are members of a binary system. The formation and evolution of binary neutron stars can be a complex process.[51] Neutron stars have been observed in binaries with ordinary main-sequence stars, red giants, white dwarfs or other neutron stars. According to modern theories of binary evolution it is expected that neutron stars also exist in binary systems with black hole companions. The merger of binaries containing two neutron stars, or a neutron star and a black hole, are expected to be prime sources for the emission of detectable gravitational waves.

text: X-ray binaries[edit]

text: Binary systems containing neutron stars often emit X-rays, which are emitted by hot gas as it falls towards the surface of the neutron star. The source of the gas is the companion star, the outer layers of which can be stripped off by the gravitational force of the neutron star if the two stars are sufficiently close. As the neutron star accretes this gas its mass can increase; if enough mass is accreted the neutron star may collapse into a black hole.[52]

text: Neutron star binary mergers and nucleosynthesis[edit]

text: Binaries containing two neutron stars are observed to shrink as gravitational waves are emitted.[53] Ultimately the neutron stars will come into contact and coalesce. The coalescence of binary neutron stars is one of the leading models for the origin of short gamma-ray bursts. Strong evidence for this model came from the observation of a kilonova associated with the short-duration gamma-ray burst GRB 130603B,[54] and finally confirmed by detection of gravitational wave GW170817 and short GRB 170817A by LIGO, Virgo and 70 observatories covering the electromagnetic spectrum observed the event.[55][56][57][58] The light emitted in the kilonova is believed to come from the radioactive decay of material ejected in the merger of the two neutron stars. This material may be responsible for the production of many of the chemical elements beyond iron,[59] as opposed to the supernova nucleosynthesis theory.

text: Planets[edit]

text: Neutron stars can host exoplanets. These can be original, circumbinary, captured, or the result of a second round of planet formation. Pulsars can also strip the atmosphere off from a star, leaving a planetary-mass remnant, which may be understood as a chthonian planet or a stellar object depending on interpretation. For pulsars, such pulsar planets can be detected with the pulsar timing method, which allows for high precision and detection of much smaller planets than with other methods. Two systems have been definitively confirmed. The first exoplanets ever to be detected were the three planets Draugr, Poltergeist and Phobetor around PSR B1257+12, discovered in 1992–1994. Of these, Draugr is the smallest exoplanet ever detected, at a mass of twice that of the Moon. Another system is PSR B1620-26, where a circumbinary planet orbits a neutron star-white dwarf binary system. Also, there are several unconfirmed candidates. Pulsar planets receive little visible light, but massive amounts of ionizing radiation and high-energy stellar wind, which makes them rather hostile environments.

text: History of discoveries[edit]

text: In 1934, Walter Baade and Fritz Zwicky proposed the existence of neutron stars,[60][d] only a year after the discovery of the neutron by Sir James Chadwick.[63] In seeking an explanation for the origin of a supernova, they tentatively proposed that in supernova explosions ordinary stars are turned into stars that consist of extremely closely packed neutrons that they called neutron stars. Baade and Zwicky correctly proposed at that time that the release of the gravitational binding energy of the neutron stars powers the supernova: "In the supernova process, mass in bulk is annihilated". Neutron stars were thought to be too faint to be detectable and little work was done on them until November 1967, when Franco Pacini pointed out that if the neutron stars were spinning and had large magnetic fields, then electromagnetic waves would be emitted. Unbeknown to him, radio astronomer Antony Hewish and his research assistant Jocelyn Bell at Cambridge were shortly to detect radio pulses from stars that are now believed to be highly magnetized, rapidly spinning neutron stars, known as pulsars.

text: In 1965, Antony Hewish and Samuel Okoye discovered "an unusual source of high radio brightness temperature in the Crab Nebula".[64] This source turned out to be the Crab Pulsar that resulted from the great supernova of 1054.

text: In 1967, Iosif Shklovsky examined the X-ray and optical observations of Scorpius X-1 and correctly concluded that the radiation comes from a neutron star at the stage of accretion.[65]

text: In 1967, Jocelyn Bell Burnell and Antony Hewish discovered regular radio pulses from PSR B1919+21. This pulsar was later interpreted as an isolated, rotating neutron star. The energy source of the pulsar is the rotational energy of the neutron star. The majority of known neutron stars (about 2000, as of 2010) have been discovered as pulsars, emitting regular radio pulses.

text: In 1971, Riccardo Giacconi, Herbert Gursky, Ed Kellogg, R. Levinson, E. Schreier, and H. Tananbaum discovered 4.8 second pulsations in an X-ray source in the constellation Centaurus, Cen X-3.[66] They interpreted this as resulting from a rotating hot neutron star. The energy source is gravitational and results from a rain of gas falling onto the surface of the neutron star from a companion star or the interstellar medium.

text: In 1974, Antony Hewish was awarded the Nobel Prize in Physics "for his decisive role in the discovery of pulsars" without Jocelyn Bell who shared in the discovery.[67]

text: In 1974, Joseph Taylor and Russell Hulse discovered the first binary pulsar, PSR B1913+16, which consists of two neutron stars (one seen as a pulsar) orbiting around their center of mass. Einstein's general theory of relativity predicts that massive objects in short binary orbits should emit gravitational waves, and thus that their orbit should decay with time. This was indeed observed, precisely as general relativity predicts, and in 1993, Taylor and Hulse were awarded the Nobel Prize in Physics for this discovery.[68]

text: In 1982, Don Backer and colleagues discovered the first millisecond pulsar, PSR B1937+21.[69] This object spins 642 times per second, a value that placed fundamental constraints on the mass and radius of neutron stars. Many millisecond pulsars were later discovered, but PSR B1937+21 remained the fastest-spinning known pulsar for 24 years, until PSR J1748-2446ad (which spins more than 700 times a second) was discovered.

text: In 2003, Marta Burgay and colleagues discovered the first double neutron star system where both components are detectable as pulsars, PSR J0737-3039.[70] The discovery of this system allows a total of 5 different tests of general relativity, some of these with unprecedented precision.

text: In 2010, Paul Demorest and colleagues measured the mass of the millisecond pulsar PSR J1614–2230 to be 1.97±0.04 M☉, using Shapiro delay.[71] This was substantially higher than any previously measured neutron star mass (1.67 M☉, see PSR J1903+0327), and places strong constraints on the interior composition of neutron stars.

text: In 2013, John Antoniadis and colleagues measured the mass of PSR J0348+0432 to be 2.01±0.04 M☉, using white dwarf spectroscopy.[72] This confirmed the existence of such massive stars using a different method. Furthermore, this allowed, for the first time, a test of general relativity using such a massive neutron star.

text: In October 2017, LIGO and Virgo made first detection of gravitational waves produced by colliding neutron stars.[73]

text: Subtypes table[edit]

text:
Neutron star

Isolated Neutron Star (INS):[38][40][74][75] not in a binary system.

Rotation-powered pulsar (RPP or "radio pulsar"):[40] neutron stars that emit directed pulses of radiation towards us at regular intervals (due to their strong magnetic fields).

Rotating radio transient (RRATs):[40] are thought to be pulsars which emit more sporadically and/or with higher pulse-to-pulse variability than the bulk of the known pulsars.

Magnetar: a neutron star with an extremely strong magnetic field (1000 times more than a regular neutron star), and long rotation periods (5 to 12 seconds).

Soft gamma repeater (SGR).[38]
Anomalous X-ray pulsar (AXP).[38]

Radio-quiet neutron stars.

X-ray Dim Isolated Neutron Stars.[40]
Central Compact Objects in Supernova remnants (CCOs in SNRs): young, radio-quiet non-pulsating X-ray sources, thought to be Isolated Neutron Stars surrounded by supernova remnants.[40]

X-ray pulsars or "accretion-powered pulsars": a class of X-ray binaries.

Low-mass X-ray binary pulsars: a class of low-mass X-ray binaries (LMXB), a pulsar with a main sequence star, white dwarf or red giant.

Millisecond pulsar (MSP) ("recycled pulsar").

Sub-millisecond pulsar.[76]

X-ray burster: a neutron star with a low mass binary companion from which matter is accreted resulting in irregular bursts of energy from the surface of the neutron star.

Intermediate-mass X-ray binary pulsars: a class of intermediate-mass X-ray binaries (IMXB), a pulsar with an intermediate mass star.
High-mass X-ray binary pulsars: a class of high-mass X-ray binaries (HMXB), a pulsar with a massive star.
Binary pulsars: a pulsar with a binary companion, often a white dwarf or neutron star.

Theorized compact stars with similar properties.

Protoneutron star (PNS), theorized.[77]
Exotic star

Quark star: currently a hypothetical type of neutron star composed of quark matter, or strange matter. As of 2008, there are three candidates.
Electroweak star: currently a hypothetical type of extremely heavy neutron star, in which the quarks are converted to leptons through the electroweak force, but the gravitational collapse of the neutron star is prevented by radiation pressure. As of 2010, there is no evidence for their existence.
Preon star: currently a hypothetical type of neutron star composed of preon matter. As of 2008, there is no evidence for the existence of preons.

tag: ul

text: Examples of neutron stars[edit]

text:
PSR J0108-1431 – closest neutron star
LGM-1 – the first recognized radio-pulsar
PSR B1257+12 – the first neutron star discovered with planets (a millisecond pulsar)
SWIFT J1756.9-2508 – a millisecond pulsar with a stellar-type companion with planetary range mass (below brown dwarf)
PSR B1509-58 source of the "Hand of God" photo shot by the Chandra X-ray Observatory.
PSR J0348+0432 – the most massive neutron star with a well-constrained mass, 2.01 ± 0.04 M☉.

text: Gallery[edit]

text: Video – animation[edit]

text:
Play media

Neutron stars containing 500,000 Earth-masses in 25 km (16 mi) diameter sphere

Play media

Neutron stars colliding

Play media

Neutron star collision


document_title: Tom Clancy's Rainbow Six Siege

question_text: when does rainbow six seige outbreak come out

text: Tom Clancy's Rainbow Six Siege

text: Gameplay

text: Tom Clancy's Rainbow Six Siege is a first-person shooter game, in which players control an operator from the Rainbow team. Different operators have different nationalities, weapons, and gadgets.[2] The game features an asymmetrical structure whereby the teams are not always balanced in their ability choices.[3] The Counter Terrorism Units (CTUs) available for play include the FBI Hostage Rescue Team, the British SAS, German GSG-9, Russian Spetsnaz and French GIGN, each of which has four operators per unit (other units were later added through downloadable content, see below). Players also have access to a "Recruit" operator who can choose from a more flexible assortment of equipment at the expense of having no unique gadget. Players pick an operator from any unit before a round starts, and are not allowed to change operators during a round. An in-game shop allows players to purchase operators using the in-game currency, "Renown", which is earned at the end of matches from actions performed in-game. The different gameplay modes award renown at different rates, with ranked matches offering the largest renown multiplier potential per match. Renown can also be affected with the addition of "boosters" which give the player a 100% increase in all renown earned for 24 hours (real time not play time). Renown can be used to purchase weapon customization options, which allow players to put attachments such as silencers and scopes on their weapons.[4] A premium credit, known as "R6 credits" can also be purchased using real world currency to get operators quicker in-game, or other cosmetic.[5]

text: In ranked play, when a round begins, the attackers choose one of several spawn points from which to launch their attack. The attackers are then given control over wheeled drones to scout the map in search of enemy operators and targets,[6] while the defenders can use security cameras to spot the attackers.[7] Maps in the game are designed to encourage close quarters combat, and players cannot respawn until the end of a round. Defenders can also put up destructible barricades and reinforce walls to make them indestructible unless you have an appropriate operator. Players who were killed by opponents can enter "Support Mode", which allows them to gain access to drone's cameras and security cameras so that they can continue to contribute to their team by informing them of opponent locations and activities.[8][9] Matches generally last only a few minutes.[10] Teamwork and cooperation is encouraged in Siege, and players need to take advantage of their different abilities in order to complete the objective and defeat the enemy team.[6] Communication between players is also encouraged.[6][11] The game also has a spectator mode, which allows players to observe a match from different angles.[12]

text: The game features heavy emphasis on environmental destruction[13][14] using a procedural destruction system. Players can break structures by planting explosives on them, or shoot walls to make bullet holes.[15] Players may gain tactical advantages through environmental destruction, and the system aims at encouraging players to utilize creativity and strategy.[15][16] A bullet-penetration system is featured, in which bullets that pass through structures deal less damage to enemies.[14] In addition to destruction, players can also set up heavy-duty fortifications on walls and deployable shields around them for protection; these can be destroyed through breaching or by utilizing operator specific melee-weapons like sledgehammers.[17] In order to stop attackers' advance, defenders can place traps like barbed-wire and explosive laserwire traps around the maps.[18] Vertical space is a key gameplay element in the game's maps: players can destroy ceilings and floors using breach charges and can ambush enemies by rappelling through windows.[6] Powerful weapons like grenades and breach charges are valuable, as only limited numbers can be used in a round.[10]

text: Modes

text: At launch, the game featured 11 maps[19] and 5 different gameplay modes. With the downloadable content (DLC) – an additional four maps from season one and the first map from season two[needs update] – there are currently 16 maps with two more slated for release by January 2018. The gameplay modes featured include:

text:
Hostage: a competitive multiplayer mode, in which the attackers must extract the hostage from the defenders, while the defenders must prevent the hostage from being rescued. A secondary manner of winning can occur if the attacking or defending team accidentally damages the hostage, causing the hostage to "down"; if the opposing team can prevent revival of the hostage, and the hostage bleeds-out and dies, they will win the round.[20]
Bomb: a competitive multiplayer mode, in which the attackers are tasked with locating and defusing one of two bombs. The defenders must stop the attackers by killing all of them or destroying the defuser.[21] If all attackers are killed after the defuser is planted, the defuser must still be destroyed for a defending victory.
Secure Area: a competitive multiplayer mode, in which the defenders must protect a room with biohazard containers, while the attackers must fight their way in. The match ends when all players from one team are killed or the biohazard container is secured by the attackers when there are no defenders in the room.[22]
Terrorist Hunt: a solo[23] or cooperative multiplayer mode for up to five players. Players take on the role of either attackers or defenders, and must fight against waves of enemies controlled by artificial intelligence.[24][25]
Situations: the game's most significant single-player component, with 11 scenarios that serve as introductions and tutorials to the game's mechanics.[26]
Tactical Realism: a variation of the standard competitive multiplayer modes, added with the release of the Operation Skull Rain DLC. The game mode features a heavier emphasis on realism and teamwork, removing most of the heads-up display (HUD) elements, the ability to mark opponents, and the ability to see teammates' contours through walls, while also featuring the addition of a realistic ammo management system.[27] This mode is not featured any more but some aspects are in the other multiplayer modes.

text: Setting

text: Three years after Rainbow Program's deactivation, there is a resurgence of terrorist activities, with the White Mask being the most prominent. The terrorists' goals are unknown, yet they are causing chaos across the world.[28] To counter this rising threat, the program is reactivated by a new leader who is simply known as Six (voiced by Angela Bassett).[29] Six assembles a group of special forces operatives from different countries to face and combat the White Masks. Recruits go through multiple exercises to prepare them for future encounters with the White Masks, training to perform hostage rescue and bomb disposal. Eventually, the White Masks launch a chemical attack on a university (called Bartlett University), and the recruits are sent to disarm the bombs and eliminate the enemy presence. The operation is a massive success, though there are casualties. The story ends with Six affirming that the reactivation of Team Rainbow is the best and only choice in a time filled with risks and uncertainties. Team Rainbow is ready for their next mission – to hunt down the leader of their enemy – and they stand prepared to protect and defend their nation from terrorists.

text: Development

text: Origin

text: This entire project was born and has grown out of an in-depth study that looked to distill what the Rainbow series is at its core in terms of both fantasy and gameplay. At the end of the day, the Rainbow Six fantasy about being part of the greatest counter-terrorist organization and impersonating the best of the best operators, working as a team, [and] carrying out dangerous operations (hostage rescue) anywhere on the globe

text: The game's predecessor was Tom Clancy's Rainbow 6: Patriots, a tactical shooter announced in 2011. It had a focus on narrative, and the story campaign features many cut-scenes and scripted events. However, the game fell into a development hell shortly after its announcement. The game's outdated engine and frequent change of leadership hindered development progress, and game quality was not up to par.[31] In addition, it was planned to be released on seventh-generation video-game consoles which were not capable of processing certain game mechanics. Seeing the arrival of a new generation of consoles, the team wanted to make use of this opportunity to create a more technologically advanced game.[32] As a result, Ubisoft decided to cancel Patriots, and assembled a new team of 25 people to come up with ideas to reboot the series.[33]

text: To make the new game feel refreshing, only certain multiplayer elements were retained as the small team took the game in a different direction. They evaluated the core of the Rainbow Six series, which they thought was about being a member of a counter-terrorist team traveling around the globe to deal with dangerous terrorist attacks – operations which are usually intense confrontations between attackers and defenders.[30] However, the team wanted to fit these ideas into a multiplayer format which would increase the game's sustainability.[34][35] These became the basic concept ideas for the game. As the development team hoped that the game can be replayed frequently, the team decided to devote all the resources into developing the game's multiplayer and abandoned the single-player campaign.[36]

text: Development of the game officially began in January 2013. Ubisoft Montreal, the developer of Patriots, handled the game's development, with Ubisoft's offices in Barcelona, Toronto, Kiev, Shanghai and Chengdu providing assistance.[37][38] The game was originally called Rainbow Six Unbreakable, a title that reflected not only the game's destruction mechanic but also the mindset of the development team, who had to deliver a game that was once stuck in development hell.[34] According to Alexandre Remy, the brand director, the team was confident in their new vision for the game but very nervous when they revealed it, realizing the change of direction would likely disappoint some fans.[33]

text: Gameplay design

text: The 150-person team consisted mainly of first-person shooter veterans or longtime Rainbow Six players.[34] Despite having prior knowledge on how these types of games work, the team decided to study historic examples of counter-terrorist operations, including 1980's London Iranian Embassy siege, 1977's Lufthansa Flight 181 hijacking, and 2002's Moscow theater hostage crisis to ensure that the portrayal of these operations was accurate and appropriate. The team also consulted counter-terrorism units, such as the National Gendarmerie Intervention Group (GIGN), for their opinions on how they would react during a hostage rescue situation.[39] According to Xavier Marquis, the game's creative director, having a hostage rescue mission in the game helped create an immersive story. By allowing players to assume control of an operator tasked with saving innocents, it gives them an objective and a priority. They must be careful in dealing with the situation and try their best not to hurt the hostage. This further promotes teamwork between players and prompts them to plan before attacking, and further makes the game more realistic, tense and immersive.[40] To make the game feel more realistic, the team introduced a mechanic called "living hostage" to govern the hostage character's behavior – e.g., coughing if there is dust in the air or shielding him or herself if there is nearby gunfire.[41]

text: The environmental destruction mechanic was one of the game's most important elements. When the game's development was begun, The developer's in-house team completed their work on RealBlast Destruction, an engine that "procedurally breaks everything down" and remodels the environment.[42] The development team thought that this technology fitted the game's style and gameplay, and decided to use it.[43] This aspect of the game became increasingly important during development, and the team spent an extended period of time making sure that these destructions were authentic. As a result, the team implemented a materials-based tearing system, in which environmental objects of different materials show different reactions to players' attacks.[14] To render the game's texture, the team used physically based rendering, even though it was ineffective during the game's early stage of production due to issues with the game's engine. A material bank and substance painter were utilized to create textures for environmental objects when they were damaged or destroyed. The team also implemented subtle visual cues to help players identify whether a structure was destructible or not, as opposed to "distracting" players with more-obvious hints.[44] The destruction mechanic prompted Ubisoft to change their level-design approach, as they had to ensure that the level was still logical and realistic when parts of the environment were destroyed.[45]

text: According to Ubisoft, "teamwork, tactics, and tension" were the game's three most important pillars. The team initially worked on a respawn feature, allowing players to rejoin after they are killed in the game. However, following several internal tournaments, the team realized that some of their employees would always win a match. They concluded that the respawn system worked to the benefit of strong players and placed individual skill above teamwork,[46] which did not fit the developer's focus on game tactics. Removing the respawn feature meant greater consequences for taking risks, and players had to rely on their teammates in order to survive and achieve objectives. According to Chris Lee, the game's designer, the team initially worried that the system would only appeal to hardcore players. However, after several testings, they found that the removal of the respawn system provided new challenges to strong players and forced them to cooperate with their teammates – while it rewarded weaker players who were willing to take their time, plan their actions, and be strategic.[47][48][49]

text: The gameplay system was designed to allow players to have a lot of freedom. As a result, the team implemented the "Golden 3C Rules", which represents Character, Control, and Camera.[50] Players are always controlling their own actions and movements, and the team intentionally avoided any animation that would disrupt the players. As a result, actions such as setting explosives, or placing a breach charge, can be cancelled immediately so that players can react and shoot. The game's camera only moves when the player moves, as the team feared that the changes of camera angle may lead to players' in-game deaths. A free-lean system was introduced to the game so that players can have more control on their line of sight.[30] According to Ubisoft, this input-driven control mechanism makes the game feel more "natural" and "fluid". This is because it allows players to concentrate on planning and coordinating, rather than thinking if the camera or environment will interfere their actions.[51]

text: Several gameplay elements were scrapped or removed from the final game. One of the features of its predecessors, artificial intelligence-controlled squadmates, were removed from single-player missions. This decision was made because the team wanted players to play with a squad controlled by actual players rather than computers. The team once considered adding a map editor so that players could design their own maps, but this plan never came to fruition. Hit markers, which would indicate an injury inflicted on an opponent, were removed because the team feared that players would abuse the system by "peppering the walls with gunfire" and use hit markers to locate enemies. Players cannot jump in the game, as real-life counter-terrorist unit operators do not jump while carrying out their missions.[48]

text: Sound design

text: According to Louis Philippe, the game's audio director, the team originally used intense music and sounds to create tension. However, the team decided to scrap this idea, realizing that the best way to create a tense atmosphere is to create the sounds of other players, which are often unexpected. The team created Navigation Sounds, in which the sound a player made is determined by their operators' weight, armor, and speed. Gadget deployment such as fortifying and breach-charging create louder sounds that may reveal the player's presence. The team thought that this would be enjoyable for players and influence their gameplay experience.[52] The game's music was composed by Paul Haslinger, who had worked on the score of the previous Rainbow Six games and the Far Cry series. His co-composer was Ben Frost, who debuted his first video game soundtrack with Siege. Leon Purviance assisted Frost and Haslinger in composing the music.[53]

text: Release

text: Ubisoft announced the game at their press conference during Electronic Entertainment Expo 2014.[54] In August 2015, Ubisoft announced that they had delayed the game's release from October 10 to December 1, 2015, in order to give additional time for the team to balance the game for cooperative multiplayer play.[55] A closed alpha-testing was held by Ubisoft on April 7–13, 2015, in which players could play an early version of the game in order to help the development team test their servers and core gameplay loops, and to provide feedback.[56] Ubisoft held a closed beta, starting on September 24, 2015, for further testing. The company originally wanted to hold another round of testing with the release of the game's open beta on November 25, 2015, but they delayed its release to November 26 due to matchmaking issues.[57] Players who purchased Siege for the Xbox One could download Tom Clancy's Rainbow Six: Vegas and its sequel, Tom Clancy's Rainbow Six: Vegas 2 for free.[58]

text: The game had multiple versions for players to purchase. A season pass was announced on November 12, 2015. Players who bought this version of the game could gain early access to operators offered in the DLCs and receive several weapon skins.[59] The game was also released alongside its Collector's Edition, which included the game's season pass, a hat, a compass and bottle opener, a backpack, and a 120-page guide.[60] A Starter Edition was released on PC in June 2016, featuring all the maps, modes and weapons of the standard edition, and included two operators plus enough Rainbow 6 Credits to purchase two more of the player's choice (players could purchase the rest of the operators with Renown or Rainbow 6 Credits). The Starter Edition was cheaper than the main game, and was initially available for a limited time.[61] In February 2017, the Starter Edition became permanently available via Uplay.[62]

text: According to Ubisoft, the game adopted a "game as a service" approach, as they would provide long-term support for the game and offer post-release content to keep players engaged. The management team initially doubted the idea, but eventually decided to approve it.[33] The title was supported with many updates upon launch, with the company introducing fixes to bugs, and improvements on both matchmaking and general gameplay mechanics.[63][64] They also introduced an auto-kick system, which automatically removes players from a match when they kill a friendly player,[65] and launched the BattleEye system in August 2016 to punish cheaters.[66] All downloadable content maps was released to all players for free.[67] The team avoided adding more modes to the game because most would not fit well with the game's close-quarter combat.[68] Downloadable content for the game were divided into several seasons, with a Mid-Season Reinforcement patch which added new weapons and modified some of the operators' core abilities.[33] This post-release content was developed by the Montreal studio in conjunction with Blue Byte in Germany.[69] Ubisoft announced that they would keep supporting the game and adding new playable characters for 10 more years. As a result, no sequel was planned.[70]

text: In January 2018, Ubisoft announced the introduction of Outbreak Packs, which are lootboxes that can be unlocked with R6 credits (which can be purchased with microtransactions) to gain character items. The company also announed that the base version of the game will be replaced by a bundle named The Advanced Edition, which includes the base game and a small amount of outbreak packs and R6 credits. The changes resulted in players' backlash, as existing players have to pay for new content while new players do not.[71] Ubisoft compensated players by giving players a free premium skin for free, and announced plans to change the Standard Edition so that players can unlock new operators at a faster pace.[72]

text:
Downloadable content and expansion packs

Year
Name
Release date
Notes

Year 1
Operation Black Ice
February 2, 2016
The DLC introduces a new map, a frozen yacht in Canada. It also introduces two Canadian operators, Frost and Buck. Frost can use a trap to incapacitate enemies, while Buck has an under-barrel shotgun.[73]

Operation Dust Line
May 11, 2016
The DLC introduces a new map set in the Middle East, which was described as "a mix of old and new construction with open air pathways".[74] It also introduces two new operators, Blackbeard and Valkyrie. Blackbeard has face shields that can be mounted onto his rifle, while Valkyrie has three Black Eye Cameras.[75]

Operation Skull Rain
August 2, 2016
The DLC introduces a new map set in Brazil, and two Brazilian operators called Capitão and Caveira.[76] Capitão has a tactical crossbow which can be loaded with asphyxiating bolts, that will burn oxygen within a certain radius, or smoke grenade bolts that create a thick cloud of smoke. Caveira has an ability called Silent Step, which allows her to interrogate an immobilized enemy for the location of other enemies.[77]

Operation Red Crow
November 17, 2016
The DLC introduces a new map set in a skyscraper in Japan, and two Japanese operators called Hibana and Echo. Hibana possesses a weapon that launches up to three sets of six explosives that can break reinforced walls, while Echo uses a drone capable of releasing sonic blasts to disorient enemies.[78]

Year 2
Operation Velvet Shell
February 8, 2017
The DLC introduces a new map set in Spain, and two Spanish operators called Mira and Jackal.[79] Jackal is a tracker who can reveal the location of enemies by tracking their footprints, while Mira can create one-way windows on walls which can be ejected, leaving a space for operators to fire through.[80][81]

Operation Health
June 6, 2017[82]
Operation Health is an update that fine-tuned many of the game's aspects, including fixes to hit boxes, spawn killing and audio issues.[83] This resulted in the delay of season 2's content and the cancellation of a map.[84]

Operation Blood Orchid
September 5, 2017[85]
The DLC introduces a new map set in Hong Kong, two Hong Kong operators named Ying and Lesion, and one Polish operator named Ela.[86] Ying utilizes candela cluster charges that can be thrown or attached to a surface to stun enemies. Lesion uses poison mines that slow and cause damage to an enemy over time when triggered. Ela possesses proximity concussion mines that can be attached to multiple surfaces to disorient enemies.[87][88]

Operation White Noise
December 5, 2017[89]
The DLC introduces a new map set in South Korea, two South Korean operators named Dokkaebi and Vigil, and one Polish operator named Zofia. Dokkaebi is able to hack cameras and enemy phones to make them ring, giving away their positions through sound. Vigil is invisible to enemy drones and cameras. Zofia carries a double barreled grenade launcher capable of launching explosive or concussion grenades.[90]

Year 3
Operation Chimera
March 6, 2018[91]
This DLC introduces one GIGN operator named Lion, and one Spetsnaz operator named Finka. Both are part of a CBRN specialist detachment of Team Rainbow. Lion uses a UAV to temporarily expose moving enemies via sonar; Finka uses nanomachines to temporarily increase the health and accuracy of herself and her teammates. This DLC also introduces "Outbreak", a PvE gamemode where some operators are tasked with containing a biohazard that has turned the citizens of Truth or Consequences, New Mexico into zombie-like monsters.[92]

tag: table

text: Ubisoft also envisioned the game as an eSports game. The company had their first meeting with David Hiltscher, vice president of ESL, in late 2013. ESL offered feedback on the game's balancing and helped the developer to ensure that the game was suitable for competitive play.[93] The team focused on introducing new operators to provide variety for eSports viewers after the game's release, a decision inspired by modern multiplayer online battle arena games such as Dota 2, as this type of game often has 80–100 playable characters.[94] ESL and Ubisoft officially announced Tom Clancy's Rainbow Six Pro League, a global tournament for Windows and Xbox One players. The competition was held at Intel Extreme Masters eSports tournament on March 4, 2016.[95] A European team, PENTA Sports, became the champion of the first season of Rainbow Six Pro League after defeating another team, GiFu, at the final of the tournament held in May 2016.[96] In 2017, It was revealed that Pro League Year Two would return, but Xbox One tournaments would not be featured.[97] Ubisoft also held the Six Invitational tournaments in 2017 and 2018, in which top teams competed for the top prize. The 2018 tournament attracted 321,000 viewers on Twitch.[98] Both Nathan Lawrence from Red Bull and Richie Shoemaker from Eurogamer compared the game favourably with Counter-Strike: Global Offensive, with both being hopeful that Siege can dethrone Global Offensive's status as the most successful competitive eSports first-person shooter in the future.[99][100]

text: Reception

text:
Reception

Aggregate score

Aggregator
Score

Metacritic
(PC) 79/100[101]
(XONE) 74/100[102]
(PS4) 73/100[103]

Review scores

Publication
Score

Destructoid
8/10[104]

Game Informer
7/10[105]

Game Revolution
[106]

GameSpot
8/10[107]

GamesRadar+
[108]

IGN
8.5/10[109]
7.9/10[110]

PC Gamer (US)
90/100[111]

Polygon
6/10[112]

VideoGamer.com
8/10[113]

text: The pre-release reception of the game was positive, with critics praising the game's design and tensions created during matches.[25] In 2014, the game received four nominations from Game Critics Awards: Best of Show, Best PC Game, Best Action Game and Best Online Multiplayer Game.[114] The game eventually became the winner of the Best PC Game category.[115]

text: Tom Clancy's Rainbow Six Siege received "generally favorable" reviews from critics, according to review aggregator Metacritic. Critics generally praised the game's destructive environment, tactical nature, map design, and its focus on teamwork. However, the lack of content and the game's microtransactions were subjected to criticism.

text: The game's multiplayer was widely praised by critics. Chris Carter from Destructoid praised the game's open-ended nature, which made each match unpredictable and helped the experience to stay fresh even after an extended period of playing.[104] GameSpot's Scott Butterworth appreciated the title for allowing players to make use of their creativity in approaching a mission.[107] James Davenport from PC Gamer echoed this thought, and he described Siege as a "psychological race" in which players are constantly trying to outwit their opponents.[111] Ryan McCaffery from IGN also praised the tactical possibilities, which make the game "tense and riveting".[110] The large number of operators available for players to choose were praised by both Carter and Matt Bertz from Game Informer, who commented that they added depths and variety to the game and that players could experiment to see which pairs of operators can complement each other.[105] However, McCaffery was disappointed by the lack of variety of game modes, and commented that most players usually neglect the mode's objectives and opted to simply eliminate their opponents.[110] Terrorist Hunt received divisive opinions from critics. Carter thought that it was more relaxing,[104] and Butterworth thought it was exhilarating. However, Bertz criticized its lack of variety, weak artificial intelligence, and its less-intense nature when compared with the player-versus-player modes.[105] Martin Robinson from Eurogamer also noted that the mode only ran at 30 frames per second, which limited its appeal.[116]

text: The game's focus on tactics was praised. Bertz applauded the tactical nature of the game, as it fostered communications between players. However, he noted that teamwork may not be possible if players did not have a headphone and microphone.[105] Arthur Gies from Polygon echoed these comments, stating that the game's over-reliance on teamwork meant that when teammates were not communicating, the game would not be fun to play.[112] The "No Respawn" system was praised by Butterworth for making each match feel intense, as even the best player needs to think tactically in order to win.[107] Jonathon Leack from Game Revolution enjoyed the scouting phase of a multiplayer match, which encouraged players to communicate with each other and coordinate their attacks.[106] However, Gies noted that the placement of game objectives does not vary much, thus making the scouting phase meaningless. Both Bertz and Butterworth agreed that the game's competitive nature increases the game's replay value.[105][107] Ben Griffin from GamesRadar praised the destruction mechanic for bringing tactical depth to the game.[108]

text: The gameplay received mixed reviews. Both Bertz and Griffin criticized the game's incompetent hit detection system, which made the experience unfair.[108] Bertz described the game's gunplay as "servicable",[105] while Leack noticed a delay in shooting, which drags the game's pace and leads to a steep learning curve. However, Leack appreciated the game's map design, which opened many possibilities. He also praised its attention to detail and sound design, which can often make a multiplayer match feel like a "great action film".[106] Bertz was disappointed by the lack of customization options, which did not offer long-term progression for the players.[105] Butterworth similarly criticized the progression system for being slow. As players cannot play as the same operator in the same match, he was often forced to play as the generic "recruit" character when he was only at the beginning stage of the game. He also criticized the limited weapon customization options, which barely affect gameplay.[107] McCaffery described customization as the "least interesting" aspect of the game, and claimed that most gameplay features were locked when players started playing.[110] Griffin, Gies, and Steven Burns from VideoGamer.com were annoyed by the microtransactions featured in the game,[113][112] with Griffin describing it as a greedy attempt by Ubisoft to make more money,[108] though Davenport did not mind these features as they were limited to cosmetic items and could be unlocked through earning Renown.[111] Bertz was annoyed the lack of clan infrastructure, which may cause players troubles when they were finding matches,[105] while Griffin thought that map rotation often felt random and was disappointed that players cannot vote to decide which map they are going to play next.[108]

text: Single-player was generally considered a disappointment by critics, with Situations receiving mixed reviews. Carter described it as one of his "favorite non-campaign additions" as the mode gave players incentive to return due to its rating system. Butterworth described it as a "surprisingly robust" mode, and thought that there were great tutorial missions that help players to understand gameplay before trying multiplayer.[107] However, Bertz criticized it for its lack of replay value,[105] and Griffin noted their short length.[108] McCaffery thought that it served as a competent tutorial, but its solo play nature meant that players could not practice teamplay and tactics.[110] Davenport criticized the narrative in Situations, which he thought was not meaningful.[111] Many critics were disappointed with the lack of a single-player campaign or a cooperative campaign,[105][106] but Butterworth believed that the strong multiplayer components can compensate for this absence.[107] Gies noticed certain network issues would affect the single-player.[112]

text: Many critics generally had a positive opinion on the package. Bertz thought that the game's multiplayer design had laid a great foundation for the game, but it was not taken advantage of due to the small number of game modes.[105] Leack felt that Siege's tight focus on tactical gameplay had "provided something unlike any other game on the market".[106] Butterworth found the game very unique and that there was "nothing else like it" when he put aside the game's minor annoyances.[107] Griffin wrote that the title felt very fresh, as most games in the market did not value tactics.[108] Davenport similarly praised the game for being very concentrated and making no compromises on gameplay design, which in turn make the title one of the best tactical multiplayer shooters on the market.[111] Gies recognized the game's potential but thought that they were overshadowed by the game's numerous technical annoyances, frustrating progression system and its lack of content.[112] Robinson was impressed by the game's multiplayer mode, and that the overall package could be considered as the year's best multiplayer game. However, he questioned Ubisoft for releasing the game with so little content while still selling it at full-price.[116]

text: Sales

text: In May 2015, CEO of Ubisoft Yves Guillemot announced that the company expected the game to outsell Far Cry 4's seven million sales over the course of its lifetime because of post-launch support.[117] At the game's launch, it debuted at number six in UK Software Charts, selling 76,000 retail copies across all three platforms.[118] Critics thought that the launch performance was underwhelming and lackluster.[119] However, through continued post-release support and updates, the player base had doubled since the game's launch.[120] Following the summer 2016 launch of the third DLC, Skull Rain, the size of the player base had a 40% increase, and the title had more than 10 million registered players.[121] Two years after launch, the game remained as one of the top 40 best-selling retail games in the UK.[45] The strong performance of Siege, alongside with Tom Clancy's The Division (2016) and Tom Clancy's Ghost Recon Wildlands (2017) boosted the total number of players of the Tom Clancy's franchise to 44 million in 2017.[122] The post-launch success for Siege further solidified Ubisoft's belief in the model of "game as a service". Future Ubisoft multiplayer-focused titles – such as For Honor – adopted this structure, in which the company would provide free DLC and updates several years after the game's official release.[123] In August 2017, Ubisoft announced that the game had passed 20 million players and that the game was played by 2.3 million players every day.[124] Two years after the game's launch, Ubisoft announced that the game has passed 25 million registered players.[125] GameSpot described Siege as "one of modern AAA gamings biggest comebacks", and the best proof to show that the "games-as-a-service" model works well, attributing its success to Ubisoft's continuous updates and the thriving community.[126]

text: Accolades

text:
Year
Award
Category
Result
Ref

2014
Game Critics Awards
Best of Show
Nominated
[114][115]

Best PC Game
Won

Best Action Game
Nominated

Best Online Multiplayer Game
Nominated

2015
Game Critics Awards
Best PC Game
Nominated
[127]

Best Action Game
Nominated

Best Online Multiplayer Game
Nominated

Gamescom 2015
Best Online Multiplayer Game
Nominated
[128]

2016
Golden Joystick Awards 2016
Best Multiplayer Game
Nominated
[129]

The Game Awards 2016
Best Multiplayer Game
Nominated
[130]

2017
Golden Joystick Awards 2017
eSports Game of the Year
Nominated
[131]

The Game Awards 2017
Best Ongoing Game
Nominated
[132]

2018
14th British Academy Games Awards
Evolving Game
Nominated
[133][134]

text: Notes

text: Jump up ^ Additional work by Ubisoft Kiev, Ubisoft Toronto, Ubisoft Barcelona.


document_title: Polysaccharide

question_text: where is the energy in a polysaccharide stored

text: Polysaccharide

text: Function[edit]

text: Structure[edit]

text: Nutrition polysaccharides are common sources of energy. Many organisms can easily break down starches into glucose; however, most organisms cannot metabolize cellulose or other polysaccharides like chitin and arabinoxylans. These carbohydrate types can be metabolized by some bacteria and protists. Ruminants and termites, for example, use microorganisms to process cellulose.

text: Even though these complex polysaccharides are not very digestible, they provide important dietary elements for humans. Called dietary fiber, these carbohydrates enhance digestion among other benefits. The main action of dietary fiber is to change the nature of the contents of the gastrointestinal tract, and to change how other nutrients and chemicals are absorbed.[6][7] Soluble fiber binds to bile acids in the small intestine, making them less likely to enter the body; this in turn lowers cholesterol levels in the blood.[8] Soluble fiber also attenuates the absorption of sugar, reduces sugar response after eating, normalizes blood lipid levels and, once fermented in the colon, produces short-chain fatty acids as byproducts with wide-ranging physiological activities (discussion below). Although insoluble fiber is associated with reduced diabetes risk, the mechanism by which this occurs is unknown.[9]

text: Not yet formally proposed as an essential macronutrient (as of 2005), dietary fiber is nevertheless regarded as important for the diet, with regulatory authorities in many developed countries recommending increases in fiber intake.[6][7][10][11]

text: Storage polysaccharides[edit]

text: Starch[edit]

text: Starch is a glucose polymer in which glucopyranose units are bonded by alpha-linkages. It is made up of a mixture of amylose (15–20%) and amylopectin (80–85%). Amylose consists of a linear chain of several hundred glucose molecules and Amylopectin is a branched molecule made of several thousand glucose units (every chain of 24–30 glucose units is one unit of Amylopectin). Starches are insoluble in water. They can be digested by breaking the alpha-linkages (glycosidic bonds). Both humans and animals have amylases, so they can digest starches. Potato, rice, wheat, and maize are major sources of starch in the human diet. The formations of starches are the ways that plants store glucose.

text: Glycogen[edit]

text: Glycogen serves as the secondary long-term energy storage in animal and fungal cells, with the primary energy stores being held in adipose tissue. Glycogen is made primarily by the liver and the muscles, but can also be made by glycogenesis within the brain and stomach.[12]

text: Glycogen is analogous to starch, a glucose polymer in plants, and is sometimes referred to as animal starch,[13] having a similar structure to amylopectin but more extensively branched and compact than starch. Glycogen is a polymer of α(1→4) glycosidic bonds linked, with α(1→6)-linked branches. Glycogen is found in the form of granules in the cytosol/cytoplasm in many cell types, and plays an important role in the glucose cycle. Glycogen forms an energy reserve that can be quickly mobilized to meet a sudden need for glucose, but one that is less compact and more immediately available as an energy reserve than triglycerides (lipids).

text: In the liver hepatocytes, glycogen can compose up to eight percent (100–120 g in an adult) of the fresh weight soon after a meal.[14] Only the glycogen stored in the liver can be made accessible to other organs. In the muscles, glycogen is found in a low concentration of one to two percent of the muscle mass. The amount of glycogen stored in the body—especially within the muscles, liver, and red blood cells[15][16][17]—varies with physical activity, basal metabolic rate, and eating habits such as intermittent fasting. Small amounts of glycogen are found in the kidneys, and even smaller amounts in certain glial cells in the brain and white blood cells. The uterus also stores glycogen during pregnancy, to nourish the embryo.[14]

text: Glycogen is composed of a branched chain of glucose residues. It is stored in liver and muscles.

text:
It is an energy reserve for animals.
It is the chief form of carbohydrate stored in animal body.
It is insoluble in water. It turns brown-red when mixed with iodine.
It also yields glucose on hydrolysis.

text:
Schematic 2-D cross-sectional view of glycogen. A core protein of glycogenin is surrounded by branches of glucose units. The entire globular granule may contain approximately 30,000 glucose units.[18]

A view of the atomic structure of a single branched strand of glucose units in a glycogen molecule.

text: Structural polysaccharides[edit]

text: Arabinoxylans[edit]

text: Arabinoxylans are found in both the primary and secondary cell walls of plants and are the copolymers of two sugars: arabinose and xylose.

text: Cellulose[edit]

text: The structural component of plants are formed primarily from cellulose. Wood is largely cellulose and lignin, while paper and cotton are nearly pure cellulose. Cellulose is a polymer made with repeated glucose units bonded together by beta-linkages. Humans and many animals lack an enzyme to break the beta-linkages, so they do not digest cellulose. Certain animals such as termites can digest cellulose, because bacteria possessing the enzyme are present in their gut. Cellulose is insoluble in water. It does not change color when mixed with iodine. On hydrolysis, it yields glucose. It is the most abundant carbohydrate in nature.

text: Chitin[edit]

text: Chitin is one of many naturally occurring polymers. It forms a structural component of many animals, such as exoskeletons. Over time it is bio-degradable in the natural environment. Its breakdown may be catalyzed by enzymes called chitinases, secreted by microorganisms such as bacteria and fungi, and produced by some plants. Some of these microorganisms have receptors to simple sugars from the decomposition of chitin. If chitin is detected, they then produce enzymes to digest it by cleaving the glycosidic bonds in order to convert it to simple sugars and ammonia.

text: Chemically, chitin is closely related to chitosan (a more water-soluble derivative of chitin). It is also closely related to cellulose in that it is a long unbranched chain of glucose derivatives. Both materials contribute structure and strength, protecting the organism.

text: Pectins[edit]

text: Pectins are a family of complex polysaccharides that contain 1,4-linked α-D-galactosyl uronic acid residues. They are present in most primary cell walls and in the non-woody parts of terrestrial plants.

text: Acidic polysaccharides[edit]

text: Acidic polysaccharides are polysaccharides that contain carboxyl groups, phosphate groups and/or sulfuric ester groups.

text: Bacterial capsular polysaccharides[edit]

text: Pathogenic bacteria commonly produce a thick, mucous-like, layer of polysaccharide. This "capsule" cloaks antigenic proteins on the bacterial surface that would otherwise provoke an immune response and thereby lead to the destruction of the bacteria. Capsular polysaccharides are water-soluble, commonly acidic, and have molecular weights on the order of 100–2000 kDa. They are linear and consist of regularly repeating subunits of one to six monosaccharides. There is enormous structural diversity; nearly two hundred different polysaccharides are produced by E. coli alone. Mixtures of capsular polysaccharides, either conjugated or native are used as vaccines.

text: Bacteria and many other microbes, including fungi and algae, often secrete polysaccharides to help them adhere to surfaces and to prevent them from drying out. Humans have developed some of these polysaccharides into useful products, including xanthan gum, dextran, welan gum, gellan gum, diutan gum and pullulan.

text: Most of these polysaccharides exhibit useful visco-elastic properties when dissolved in water at very low levels.[19] This makes various liquids used in everyday life, such as some foods, lotions, cleaners, and paints, viscous when stationary, but much more free-flowing when even slight shear is applied by stirring or shaking, pouring, wiping, or brushing. This property is named pseudoplasticity or shear thinning; the study of such matters is called rheology.

text:
Viscosity of Welan gum

Shear Rate (rpm)
Viscosity (cP)

0.3
23,330

0.5
16,000

1
11,000

2
5500

4
3250

5
2900

10
1700

20
900

50
520

100
310

text: Aqueous solutions of the polysaccharide alone have a curious behavior when stirred: after stirring ceases, the solution initially continues to swirl due to momentum, then slows to a standstill due to viscosity and reverses direction briefly before stopping. This recoil is due to the elastic effect of the polysaccharide chains, previously stretched in solution, returning to their relaxed state.

text: Cell-surface polysaccharides play diverse roles in bacterial ecology and physiology. They serve as a barrier between the cell wall and the environment, mediate host-pathogen interactions, and form structural components of biofilms. These polysaccharides are synthesized from nucleotide-activated precursors (called nucleotide sugars) and, in most cases, all the enzymes necessary for biosynthesis, assembly and transport of the completed polymer are encoded by genes organized in dedicated clusters within the genome of the organism. Lipopolysaccharide is one of the most important cell-surface polysaccharides, as it plays a key structural role in outer membrane integrity, as well as being an important mediator of host-pathogen interactions.

text: The enzymes that make the A-band (homopolymeric) and B-band (heteropolymeric) O-antigens have been identified and the metabolic pathways defined.[20] The exopolysaccharide alginate is a linear copolymer of β-1,4-linked D-mannuronic acid and L-guluronic acid residues, and is responsible for the mucoid phenotype of late-stage cystic fibrosis disease. The pel and psl loci are two recently discovered gene clusters that also encode exopolysaccharides found to be important for biofilm formation. Rhamnolipid is a biosurfactant whose production is tightly regulated at the transcriptional level, but the precise role that it plays in disease is not well understood at present. Protein glycosylation, particularly of pilin and flagellin, became a focus of research by several groups from about 2007, and has been shown to be important for adhesion and invasion during bacterial infection.[21]

text: Chemical identification tests for polysaccharides[edit]

text: Periodic acid-Schiff stain (PAS)[edit]

text: This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (March 2013) (Learn how and when to remove this template message)

text: Polysaccharides with unprotected vicinal diols or amino sugars (i.e. some OH groups replaced with amine) give a positive periodic acid-Schiff stain (PAS). The list of polysaccharides that stain with PAS is long. Although mucins of epithelial origins stain with PAS, mucins of connective tissue origin have so many acidic substitutions that they do not have enough glycol or amino-alcohol groups left to react with PAS.