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Sparse Fourier transform	Definition	Consider a sequence xn of complex numbers. By Fourier series, xn can be written as xn=(F∗X)n=∑k=0N−1Xkej2πNkn. Similarly, Xk can be represented as Xk=1N(Fx)k=1N∑k=0N−1xne−j2πNkn. Hence, from the equations above, the mapping is F:CN→CN Single frequency recovery Assume only a single frequency exists in the sequence. In order to recover this frequency from the sequence, it is reasonable to utilize the relationship between adjacent points of the sequence. Phase encoding The phase k can be obtained by dividing the adjacent points of the sequence. In other words, cos sin ⁡(2πkN). Notice that xn∈CN An aliasing-based search Seeking phase k can be done by Chinese remainder theorem (CRT).Take 104,134 for an example. Now, we have three relatively prime integers 100, 101, and 103. Thus, the equation can be described as 104,134 34 mod 00 mod 01 mod 03.
Sparse Fourier transform	Definition	By CRT, we have 104,134 mod 100 101 103 104,134 mod 040,300 Randomly binning frequencies Now, we desire to explore the case of multiple frequencies, instead of a single frequency. The adjacent frequencies can be separated by the scaling c and modulation b properties. Namely, by randomly choosing the parameters of c and b, the distribution of all frequencies can be almost a uniform distribution. The figure Spread all frequencies reveals by randomly binning frequencies, we can utilize the single frequency recovery to seek the main components.
Sparse Fourier transform	Definition	xn′=Xkej2πN(c⋅k+b), where c is scaling property and b is modulation property. By randomly choosing c and b, the whole spectrum can be looked like uniform distribution. Then, taking them into filter banks can separate all frequencies, including Gaussians, indicator functions, spike trains, and Dolph-Chebyshev filters. Each bank only contains a single frequency.
Sparse Fourier transform	The prototypical SFT	Generally, all SFT follows the three stages Identifying frequencies By randomly bining frequencies, all components can be separated. Then, taking them into filter banks, so each band only contains a single frequency. It is convenient to use the methods we mentioned to recover this signal frequency. Estimating coefficients After identifying frequencies, we will have many frequency components. We can use Fourier transform to estimate their coefficients. Xk′=1L∑l=1Lxn′e−j2πNn′ℓ Repeating Finally, repeating these two stages can we extract the most important components from the original signal. xn−∑k′=1kXk′ej2πNk′n
Sparse Fourier transform	Sparse Fourier transform in the discrete setting	In 2012, Hassanieh, Indyk, Katabi, and Price proposed an algorithm that takes log log ⁡(n/k)) samples and runs in the same running time.
Sparse Fourier transform	Sparse Fourier transform in the high dimensional setting	In 2014, Indyk and Kapralov proposed an algorithm that takes log log ⁡n samples and runs in nearly linear time in n . In 2016, Kapralov proposed an algorithm that uses sublinear samples log log log ⁡n and sublinear decoding time log O(d)⁡n . In 2019, Nakos, Song, and Wang introduced a new algorithm which uses nearly optimal samples log log ⁡k) and requires nearly linear time decoding time. A dimension-incremental algorithm was proposed by Potts, Volkmer based on sampling along rank-1 lattices.
Sparse Fourier transform	Sparse Fourier transform in the continuous setting	There are several works about generalizing the discrete setting into the continuous setting.
Sparse Fourier transform	Implementations	There are several works based on MIT, MSU, ETH and Universtity of Technology Chemnitz [TUC]. Also, they are free online. MSU implementations ETH implementations MIT implementations GitHub TUC implementations
Morpheus (1998 video game)	Morpheus (1998 video game)	Morpheus is an American computer game released in 1998.
Morpheus (1998 video game)	Gameplay	The game is a first-person adventure game similar to Myst with a point and click interface however, the player may also pan around a location by clicking and dragging the mouse. Clicking the mouse to go in a certain direction results in a transition video showing the player's movement.
Morpheus (1998 video game)	Reception	Morpheus became a hit in Spain, with sales of 50,000 units in that region. Bob Mandel of The Adrenaline Vault gave the game the "Seal of Excellence".
UDP-2,3-diacetamido-2,3-dideoxyglucuronic acid 2-epimerase	UDP-2,3-diacetamido-2,3-dideoxyglucuronic acid 2-epimerase	UDP-2,3-diacetamido-2,3-dideoxyglucuronic acid 2-epimerase (EC 5.1.3.23, UDP-GlcNAc3NAcA 2-epimerase, UDP-alpha-D-GlcNAc3NAcA 2-epimerase, 2,3-diacetamido-2,3-dideoxy-alpha-D-glucuronic acid 2-epimerase, WbpI, WlbD) is an enzyme with systematic name 2,3-diacetamido-2,3-dideoxy-alpha-D-glucuronate 2-epimerase. This enzyme catalyses the following chemical reaction UDP-2,3-diacetamido-2,3-dideoxy-alpha-D-glucuronate ⇌ UDP-2,3-diacetamido-2,3-dideoxy-alpha-D-mannuronateThis enzyme participates in the biosynthetic pathway for UDP-alpha-D-ManNAc3NAcA.
ATLAS experiment	ATLAS experiment	ATLAS is the largest general-purpose particle detector experiment at the Large Hadron Collider (LHC), a particle accelerator at CERN (the European Organization for Nuclear Research) in Switzerland. The experiment is designed to take advantage of the unprecedented energy available at the LHC and observe phenomena that involve highly massive particles which were not observable using earlier lower-energy accelerators. ATLAS was one of the two LHC experiments involved in the discovery of the Higgs boson in July 2012. It was also designed to search for evidence of theories of particle physics beyond the Standard Model.
ATLAS experiment	ATLAS experiment	The experiment is a collaboration involving 6,003 members, out of which 3,822 are physicists (last update: June 26, 2022) from 257 institutions in 42 countries.
ATLAS experiment	History	Particle accelerator growth The first cyclotron, an early type of particle accelerator, was built by Ernest O. Lawrence in 1931, with a radius of just a few centimetres and a particle energy of 1 megaelectronvolt (MeV). Since then, accelerators have grown enormously in the quest to produce new particles of greater and greater mass. As accelerators have grown, so too has the list of known particles that they might be used to investigate.
ATLAS experiment	History	ATLAS Collaboration The ATLAS Collaboration, the international group of physicists belonging to different universities and research centres who built and run the detector, was formed in 1992 when the proposed EAGLE (Experiment for Accurate Gamma, Lepton and Energy Measurements) and ASCOT (Apparatus with Super Conducting Toroids) collaborations merged their efforts to build a single, general-purpose particle detector for a new particle accelerator, the Large Hadron Collider. At present, the ATLAS Collaboration involves 5,767 members, out of which 2,646 are physicists (last census: September 9, 2021) from 180 institutions in 40 countries.
ATLAS experiment	History	Detector design and construction The design was a combination of two previous projects for LHC, EAGLE and ASCOT, and also benefitted from the detector research and development that had been done for the Superconducting Super Collider, a US project interrupted in 1993. The ATLAS experiment was proposed in its current form in 1994, and officially funded by the CERN member countries in 1995. Additional countries, universities, and laboratories have joined in subsequent years. Construction work began at individual institutions, with detector components then being shipped to CERN and assembled in the ATLAS experiment pit starting in 2003.
ATLAS experiment	History	Detector operation Construction was completed in 2008 and the experiment detected its first single proton beam events on 10 September of that year.
ATLAS experiment	History	Data-taking was then interrupted for over a year due to an LHC magnet quench incident. On 23 November 2009, the first proton–proton collisions occurred at the LHC and were recorded by ATLAS, at a relatively low injection energy of 900 GeV in the center of mass of the collision. Since then, the LHC energy has been increasing: 1.8 TeV at the end of 2009, 7 TeV for the whole of 2010 and 2011, then 8 TeV in 2012. The first data-taking period performed between 2010 and 2012 is referred to as Run I. After a long shutdown (LS1) in 2013 and 2014, in 2015 ATLAS saw 13 TeV collisions.
ATLAS experiment	History	The second data-taking period, Run II, was completed, always at 13 TeV energy, at the end of 2018 with a recorded integrated luminosity of nearly 140 fb−1 (inverse femtobarn). A second long shutdown (LS2) in 2019-22 with upgrades to the ATLAS detector was followed by Run III, which started in July 2022. Leadership The ATLAS Collaboration is currently led by Spokesperson Andreas Hoecker and Deputy Spokespersons Marumi Kado and Manuella Vincter. Former Spokespersons have been:
ATLAS experiment	Experimental program	In the field of particle physics, ATLAS studies different types of processes detected or detectable in energetic collisions at the Large Hadron Collider (LHC). For the processes already known, it is a matter of measuring more and more accurately the properties of known particles or finding quantitative confirmations of the Standard model. Processes not observed so far would allow, if detected, to discover new particles or to have confirmation of physical theories that go beyond the Standard model.
ATLAS experiment	Experimental program	Standard Model The Standard model of particle physics is the theory describing three of the four known fundamental forces (the electromagnetic, weak, and strong interactions, while omitting gravity) in the universe, as well as classifying all known elementary particles. It was developed in stages throughout the latter half of the 20th century, through the work of many scientists around the world, with the current formulation being finalized in the mid-1970s upon experimental confirmation of the existence of quarks. Since then, confirmation of the top quark (1995), the tau neutrino (2000), and the Higgs boson (2012) have added further credence to the Standard model. In addition, the Standard Model has predicted various properties of weak neutral currents and the W and Z bosons with great accuracy.
ATLAS experiment	Experimental program	Although the Standard model is believed to be theoretically self-consistent and has demonstrated huge successes in providing experimental predictions, it leaves some phenomena unexplained and falls short of being a complete theory of fundamental interactions. It does not fully explain baryon asymmetry, incorporate the full theory of gravitation as described by general relativity, or account for the accelerating expansion of the universe as possibly described by dark energy. The model does not contain any viable dark matter particle that possesses all of the required properties deduced from observational cosmology. It also does not incorporate neutrino oscillations and their non-zero masses.
ATLAS experiment	Experimental program	Precision measurements With the important exception of the Higgs boson, detected by the ATLAS and the CMS experiments in 2012, all of the particles predicted by the Standard Model had been observed by previous experiments. In this field, in addition to the discovery of the Higgs boson, the experimental work of ATLAS has focused on precision measurements, aimed at determining with ever greater accuracy the many physical parameters of theory.
ATLAS experiment	Experimental program	In particular for the Higgs boson; W and Z bosons; the top and bottom quarksATLAS measures: masses; channels of production, decay and mean lifetimes; interaction mechanisms and coupling constants for electroweak and strong interactions.For example, the data collected by ATLAS made it possible in 2018 to measure the mass [(8037±19) MeV] of the W boson, one of the two mediators of the weak interaction, with a measurement uncertainty of ±2.4‰.
ATLAS experiment	Experimental program	Higgs boson One of the most important goals of ATLAS was to investigate a missing piece of the Standard Model, the Higgs boson. The Higgs mechanism, which includes the Higgs boson, gives mass to elementary particles, leading to differences between the weak force and electromagnetism by giving the W and Z bosons mass while leaving the photon massless.
ATLAS experiment	Experimental program	On July 4, 2012, ATLAS — together with CMS, its sister experiment at the LHC — reported evidence for the existence of a particle consistent with the Higgs boson at a confidence level of 5 sigma, with a mass around 125 GeV, or 133 times the proton mass. This new "Higgs-like" particle was detected by its decay into two photons ( H→γγ ) and its decay to four leptons ( H→ZZ∗→4l and H→WW∗→eνμν ).
ATLAS experiment	Experimental program	In March 2013, in the light of the updated ATLAS and CMS results, CERN announced that the new particle was indeed a Higgs boson. The experiments were also able to show that the properties of the particle as well as the ways it interacts with other particles were well-matched with those of a Higgs boson, which is expected to have spin 0 and positive parity. Analysis of more properties of the particle and data collected in 2015 and 2016 confirmed this further.In October 2013, two of the theoretical physicists who predicted the existence of the Standard Model Higgs boson, Peter Higgs and François Englert, were awarded the Nobel Prize in Physics.
ATLAS experiment	Experimental program	Top quark properties The properties of the top quark, discovered at Fermilab in 1995, had been measured approximately. With much greater energy and greater collision rates, the LHC produces a tremendous number of top quarks, allowing ATLAS to make much more precise measurements of its mass and interactions with other particles. These measurements provide indirect information on the details of the Standard Model, with the possibility of revealing inconsistencies that point to new physics.
ATLAS experiment	Experimental program	Beyond the Standard model While the Standard Model predicts that quarks, leptons and neutrinos should exist, it does not explain why the masses of these particles are so different (they differ by orders of magnitude). Furthermore, the mass of the neutrinos should be, according to the Standard Model, exactly zero as that of the photon. Instead, neutrinos have mass. In 1998 research results at detector Super-Kamiokande determined that neutrinos can oscillate from one flavor to another, which dictates that they have a mass other than zero. For these and other reasons, many particle physicists believe it is possible that the Standard Model will break down at energies at the teraelectronvolt (TeV) scale or higher. Most alternative theories, the Grand Unified Theories (GUTs) including Supersymmetry (SUSY), predicts the existence of new particles with masses greater than those of Standard Model.
ATLAS experiment	Experimental program	Supersymmetry Most of the currently proposed theories predict new higher-mass particles, some of which may be light enough to be observed by ATLAS. Models of supersymmetry involve new, highly massive particles. In many cases these decay into high-energy quarks and stable heavy particles that are very unlikely to interact with ordinary matter. The stable particles would escape the detector, leaving as a signal one or more high-energy quark jets and a large amount of "missing" momentum. Other hypothetical massive particles, like those in the Kaluza–Klein theory, might leave a similar signature. The data collected up to the end of LHC Run II do not show evidence of supersymmetric or unexpected particles, the research of which will continue in the data that will be collected from Run III onwards.
ATLAS experiment	Experimental program	CP violation The asymmetry between the behavior of matter and antimatter, known as CP violation, is also being investigated. Recent experiments dedicated to measurements of CP violation, such as BaBar and Belle, have not detected sufficient CP violation in the Standard Model to explain the lack of detectable antimatter in the universe. It is possible that new models of physics will introduce additional CP violation, shedding light on this problem. Evidence supporting these models might either be detected directly by the production of new particles, or indirectly by measurements of the properties of B- and D-mesons. LHCb, an LHC experiment dedicated to B-mesons, is likely to be better suited to the latter.
ATLAS experiment	Experimental program	Microscopic black holes Some hypotheses, based on the ADD model, involve large extra dimensions and predict that micro black holes could be formed by the LHC. These would decay immediately by means of Hawking radiation, producing all particles in the Standard Model in equal numbers and leaving an unequivocal signature in the ATLAS detector.
ATLAS experiment	ATLAS detector	The ATLAS detector is 46 metres long, 25 metres in diameter, and weighs about 7,000 tonnes; it contains some 3,000 km of cable.At 27 km in circumference, the Large Hadron Collider (LHC) at CERN collides two beams of protons together, with each proton carrying up to 6.8 TeV of energy – enough to produce particles with masses significantly greater than any particles currently known, if these particles exist. When the proton beams produced by the Large Hadron Collider interact in the center of the detector, a variety of different particles with a broad range of energies are produced.
ATLAS experiment	ATLAS detector	General-purpose requirements The ATLAS detector is designed to be general-purpose. Rather than focusing on a particular physical process, ATLAS is designed to measure the broadest possible range of signals. This is intended to ensure that whatever form any new physical processes or particles might take, ATLAS will be able to detect them and measure their properties. ATLAS is designed to detect these particles, namely their masses, momentum, energies, lifetime, charges, and nuclear spins.
ATLAS experiment	ATLAS detector	Experiments at earlier colliders, such as the Tevatron and Large Electron–Positron Collider, were also designed for general-purpose detection. However, the beam energy and extremely high rate of collisions require ATLAS to be significantly larger and more complex than previous experiments, presenting unique challenges of the Large Hadron Collider.
ATLAS experiment	ATLAS detector	Layered design In order to identify all particles produced at the interaction point where the particle beams collide, the detector is designed in layers made up of detectors of different types, each of which is designed to observe specific types of particles. The different traces that particles leave in each layer of the detector allow for effective particle identification and accurate measurements of energy and momentum. (The role of each layer in the detector is discussed below.) As the energy of the particles produced by the accelerator increases, the detectors attached to it must grow to effectively measure and stop higher-energy particles. As of 2022, the ATLAS detector is the largest ever built at a particle collider.
ATLAS experiment	ATLAS detector	Detector systems The ATLAS detector consists of a series of ever-larger concentric cylinders around the interaction point where the proton beams from the LHC collide. Maintaining detector performance in the high radiation areas immediately surrounding the proton beams is a significant engineering challenge. The detector can be divided into four major systems: Inner Detector; Calorimeters; Muon Spectrometer; Magnet system.Each of these is in turn made of multiple layers. The detectors are complementary: the Inner Detector tracks particles precisely, the calorimeters measure the energy of easily stopped particles, and the muon system makes additional measurements of highly penetrating muons. The two magnet systems bend charged particles in the Inner Detector and the Muon Spectrometer, allowing their electric charges and momenta to be measured.
ATLAS experiment	ATLAS detector	The only established stable particles that cannot be detected directly are neutrinos; their presence is inferred by measuring a momentum imbalance among detected particles. For this to work, the detector must be "hermetic", meaning it must detect all non-neutrinos produced, with no blind spots. The installation of all the above detector systems was finished in August 2008. The detectors collected millions of cosmic rays during the magnet repairs which took place between fall 2008 and fall 2009, prior to the first proton collisions. The detector operated with close to 100% efficiency and provided performance characteristics very close to its design values.
ATLAS experiment	ATLAS detector	Inner Detector The Inner Detector begins a few centimetres from the proton beam axis, extends to a radius of 1.2 metres, and is 6.2 metres in length along the beam pipe. Its basic function is to track charged particles by detecting their interaction with material at discrete points, revealing detailed information about the types of particles and their momentum. The Inner Detector has three parts, which are explained below.
ATLAS experiment	ATLAS detector	The magnetic field surrounding the entire inner detector causes charged particles to curve; the direction of the curve reveals a particle's charge and the degree of curvature reveals its momentum. The starting points of the tracks yield useful information for identifying particles; for example, if a group of tracks seem to originate from a point other than the original proton–proton collision, this may be a sign that the particles came from the decay of a hadron with a bottom quark (see b-tagging).
ATLAS experiment	ATLAS detector	Pixel Detector The Pixel Detector, the innermost part of the detector, contains four concentric layers and three disks on each end-cap, with a total of 1,744 modules, each measuring 2 centimetres by 6 centimetres. The detecting material is 250 µm thick silicon. Each module contains 16 readout chips and other electronic components. The smallest unit that can be read out is a pixel (50 by 400 micrometres); there are roughly 47,000 pixels per module.
ATLAS experiment	ATLAS detector	The minute pixel size is designed for extremely precise tracking very close to the interaction point. In total, the Pixel Detector has over 92 million readout channels, which is about 50% of the total readout channels of the whole detector. Having such a large count created a considerable design and engineering challenge. Another challenge was the radiation to which the Pixel Detector is exposed because of its proximity to the interaction point, requiring that all components be radiation hardened in order to continue operating after significant exposures.
ATLAS experiment	ATLAS detector	Semi-Conductor Tracker The Semi-Conductor Tracker (SCT) is the middle component of the inner detector. It is similar in concept and function to the Pixel Detector but with long, narrow strips rather than small pixels, making coverage of a larger area practical. Each strip measures 80 micrometres by 12 centimetres. The SCT is the most critical part of the inner detector for basic tracking in the plane perpendicular to the beam, since it measures particles over a much larger area than the Pixel Detector, with more sampled points and roughly equal (albeit one-dimensional) accuracy. It is composed of four double layers of silicon strips, and has 6.3 million readout channels and a total area of 61 square meters.
ATLAS experiment	ATLAS detector	Transition Radiation Tracker The Transition Radiation Tracker (TRT), the outermost component of the inner detector, is a combination of a straw tracker and a transition radiation detector. The detecting elements are drift tubes (straws), each four millimetres in diameter and up to 144 centimetres long. The uncertainty of track position measurements (position resolution) is about 200 micrometres. This is not as precise as those for the other two detectors, but it was necessary to reduce the cost of covering a larger volume and to have transition radiation detection capability. Each straw is filled with gas that becomes ionized when a charged particle passes through. The straws are held at about −1,500 V, driving the negative ions to a fine wire down the centre of each straw, producing a current pulse (signal) in the wire. The wires with signals create a pattern of 'hit' straws that allow the path of the particle to be determined. Between the straws, materials with widely varying indices of refraction cause ultra-relativistic charged particles to produce transition radiation and leave much stronger signals in some straws. Xenon and argon gas is used to increase the number of straws with strong signals. Since the amount of transition radiation is greatest for highly relativistic particles (those with a speed very near the speed of light), and because particles of a particular energy have a higher speed the lighter they are, particle paths with many very strong signals can be identified as belonging to the lightest charged particles: electrons and their antiparticles, positrons. The TRT has about 298,000 straws in total.
ATLAS experiment	ATLAS detector	Calorimeters The calorimeters are situated outside the solenoidal magnet that surrounds the Inner Detector. Their purpose is to measure the energy from particles by absorbing it. There are two basic calorimeter systems: an inner electromagnetic calorimeter and an outer hadronic calorimeter. Both are sampling calorimeters; that is, they absorb energy in high-density metal and periodically sample the shape of the resulting particle shower, inferring the energy of the original particle from this measurement.
ATLAS experiment	ATLAS detector	Electromagnetic calorimeter The electromagnetic (EM) calorimeter absorbs energy from particles that interact electromagnetically, which include charged particles and photons. It has high precision, both in the amount of energy absorbed and in the precise location of the energy deposited. The angle between the particle's trajectory and the detector's beam axis (or more precisely the pseudorapidity) and its angle within the perpendicular plane are both measured to within roughly 0.025 radians. The barrel EM calorimeter has accordion shaped electrodes and the energy-absorbing materials are lead and stainless steel, with liquid argon as the sampling material, and a cryostat is required around the EM calorimeter to keep it sufficiently cool.
ATLAS experiment	ATLAS detector	Hadron calorimeter The hadron calorimeter absorbs energy from particles that pass through the EM calorimeter, but do interact via the strong force; these particles are primarily hadrons. It is less precise, both in energy magnitude and in the localization (within about 0.1 radians only). The energy-absorbing material is steel, with scintillating tiles that sample the energy deposited. Many of the features of the calorimeter are chosen for their cost-effectiveness; the instrument is large and comprises a huge amount of construction material: the main part of the calorimeter – the tile calorimeter – is 8 metres in diameter and covers 12 metres along the beam axis. The far-forward sections of the hadronic calorimeter are contained within the forward EM calorimeter's cryostat, and use liquid argon as well, while copper and tungsten are used as absorbers.
ATLAS experiment	ATLAS detector	Muon Spectrometer The Muon Spectrometer is an extremely large tracking system, consisting of three parts: A magnetic field provided by three toroidal magnets; A set of 1200 chambers measuring with high spatial precision the tracks of the outgoing muons; A set of triggering chambers with accurate time-resolution.The extent of this sub-detector starts at a radius of 4.25 m close to the calorimeters out to the full radius of the detector (11 m). Its tremendous size is required to accurately measure the momentum of muons, which first go through all the other elements of the detector before reaching the muon spectrometer. It was designed to measure, standalone, the momentum of 100 GeV muons with 3% accuracy and of 1 TeV muons with 10% accuracy. It was vital to go to the lengths of putting together such a large piece of equipment because a number of interesting physical processes can only be observed if one or more muons are detected, and because the total energy of particles in an event could not be measured if the muons were ignored. It functions similarly to the Inner Detector, with muons curving so that their momentum can be measured, albeit with a different magnetic field configuration, lower spatial precision, and a much larger volume. It also serves the function of simply identifying muons – very few particles of other types are expected to pass through the calorimeters and subsequently leave signals in the Muon Spectrometer. It has roughly one million readout channels, and its layers of detectors have a total area of 12,000 square meters.
ATLAS experiment	ATLAS detector	Magnet System The ATLAS detector uses two large superconducting magnet systems to bend the trajectory of charged particles, so that their momenta can be measured. This bending is due to the Lorentz force, whose modulus is proportional to the electric charge q of the particle, to its speed v and to the intensity B of the magnetic field: F=qvB. Since all particles produced in the LHC's proton collisions are traveling at very close to the speed of light in vacuum (v≃c) , the Lorentz force is about the same for all the particles with same electric charge q :F≃qcB. The radius of curvature r due to the Lorentz force is equal to r=pqB. where p=γmv is the relativistic momentum of the particle. As a result, high-momentum particles curve very little (large r ), while low-momentum particles curve significantly (small r ). The amount of curvature can be quantified and the particle momentum can be determined from this value.
ATLAS experiment	ATLAS detector	Solenoid Magnet The inner solenoid produces a two tesla magnetic field surrounding the Inner Detector. This high magnetic field allows even very energetic particles to curve enough for their momentum to be determined, and its nearly uniform direction and strength allow measurements to be made very precisely. Particles with momenta below roughly 400 MeV will be curved so strongly that they will loop repeatedly in the field and most likely not be measured; however, this energy is very small compared to the several TeV of energy released in each proton collision.
ATLAS experiment	ATLAS detector	Toroid Magnets The outer toroidal magnetic field is produced by eight very large air-core superconducting barrel loops and two smaller end-caps air toroidal magnets, for a total of 24 barrel loops all situated outside the calorimeters and within the muon system. This magnetic field extends in an area 26 metres long and 20 metres in diameter, and it stores 1.6 gigajoules of energy. Its magnetic field is not uniform, because a solenoid magnet of sufficient size would be prohibitively expensive to build. It varies between 2 and 8 Teslameters.
ATLAS experiment	ATLAS detector	Forward detectors The ATLAS detector is complemented by a set of four sub-detectors in the forward region to measure particles at very small angles.
ATLAS experiment	ATLAS detector	LUCID (LUminosity Cherenkov Integrating Detector) is the first of these detectors designed to measure luminosity, and located in the ATLAS cavern at 17 m from the interaction point between the two muon endcaps; ZDC (Zero Degree Calorimeter) is designed to measure neutral particles on-axis to the beam, and located at 140 m from the IP in the LHC tunnel where the two beams are split back into separate beam pipes; AFP (Atlas Forward Proton) is designed to tag diffractive events, and located at 204 m and 217 m; ALFA (Absolute Luminosity For ATLAS) is designed to measure elastic proton scattering located at 240 m just before the bending magnets of the LHC arc.
ATLAS experiment	ATLAS detector	Data systems Data generation Earlier particle detector read-out and event detection systems were based on parallel shared buses such as VMEbus or FASTBUS. Since such a bus architecture cannot keep up with the data requirements of the LHC detectors, all the ATLAS data acquisition systems rely on high-speed point-to-point links and switching networks. Even with advanced electronics for data reading and storage, the ATLAS detector generates too much raw data to read out or store everything: about 25 MB per raw event, multiplied by 40 million beam crossings per second (40 MHz) in the center of the detector. This produces a total of 1 petabyte of raw data per second. By avoiding to write empty segments of each event (zero suppression), which do not contain physical information, the average size of an event is reduced to 1.6 MB, for a total of 64 terabyte of data per second.
ATLAS experiment	ATLAS detector	Trigger system The trigger system uses fast event reconstruction to identify, in real time, the most interesting events to retain for detailed analysis. In the second data-taking period of the LHC, Run-2, there were two distinct trigger levels: The Level 1 trigger (L1), implemented in custom hardware at the detector site. The decision to save or reject an event data is made in less than 2.5 μs. It uses reduced granularity information from the calorimeters and the muon spectrometer, and reduces the rate of events in the read-out from 40 MHz to 100 kHz. The L1 rejection factor in therefore equal to 400.
ATLAS experiment	ATLAS detector	The High Level Trigger trigger (HLT), implemented in software, uses a computer battery consisting of approximately 40,000 CPUs. In order to decide which of the 100,000 events per second coming from L1 to save, specific analyses of each collision are carried out in 200 μs. The HLT uses limited regions of the detector, so-called Regions of Interest (RoI), to be reconstructed with the full detector granularity, including tracking, and allows matching of energy deposits to tracks. The HLT rejection factor is 100: after this step, the rate of events is reduced from 100 to 1 kHz. The remaining data, corresponding to about 1,000 events per second, are stored for further analyses.
ATLAS experiment	ATLAS detector	Analysis process ATLAS permanently records more than 10 petabyte of data per year.
ATLAS experiment	ATLAS detector	Offline event reconstruction is performed on all permanently stored events, turning the pattern of signals from the detector into physics objects, such as jets, photons, and leptons. Grid computing is being used extensively for event reconstruction, allowing the parallel use of university and laboratory computer networks throughout the world for the CPU-intensive task of reducing large quantities of raw data into a form suitable for physics analysis. The software for these tasks has been under development for many years, and refinements are ongoing, even after data collection has begun.
ATLAS experiment	ATLAS detector	Individuals and groups within the collaboration are continuously writing their own code to perform further analyses of these objects, searching the patterns of detected particles for particular physical models or hypothetical particles. This activity requires processing 25 petabyte of data per week.
ATLAS experiment	Trivia	The researcher pictured for scale in the famous ATLAS detector image is Roger Ruber, a researcher from Uppsala University, Sweden. Ruber, one of the researchers responsible for the ATLAS detector's central cryostat magnet, was inspecting the magnets in the LHC tunnel at the same time Maximilien Brice, the photographer, was setting up to photograph the ATLAS detector. Brice asked Ruber to stand at the base of the detector to illustrate the scale of the ATLAS detector. This was revealed by Maximilien Brice, and confirmed by Roger Ruber during interviews in 2020 with Rebecca Smethurst of the University of Oxford.
MAC service data unit	MAC service data unit	MAC service data unit (media access control service data unit, MSDU) is the service data unit that is received from the logical link control (LLC) sub-layer which lies above the media access control (MAC) sub-layer in a protocol stack. The LLC and MAC sub-layers are collectively referred to as the data link layer (DLL).
Clausius–Mossotti relation	Clausius–Mossotti relation	In electromagnetism, the Clausius–Mossotti relation, named for O. F. Mossotti and Rudolf Clausius, expresses the dielectric constant (relative permittivity, εr) of a material in terms of the atomic polarizability, α, of the material's constituent atoms and/or molecules, or a homogeneous mixture thereof. It is equivalent to the Lorentz–Lorenz equation, which relates the refractive index (rather than the dielectric constant) of a substance to its polarizability. It may be expressed as: where εr=εε0 is the dielectric constant of the material, which for non-magnetic materials is equal to n2, where n is the refractive index; ε0 is the permittivity of free space; N is the number density of the molecules (number per cubic meter); α is the molecular polarizability in SI-units [C·m2/V].In the case that the material consists of a mixture of two or more species, the right hand side of the above equation would consist of the sum of the molecular polarizability contribution from each species, indexed by i in the following form: In the CGS system of units the Clausius–Mossotti relation is typically rewritten to show the molecular polarizability volume α′=α4πε0 which has units of volume [m3]. Confusion may arise from the practice of using the shorter name "molecular polarizability" for both α and α′ within literature intended for the respective unit system.
Clausius–Mossotti relation	Clausius–Mossotti relation	The Clausius-Mossotti relation assumes only an induced dipole relevant to its polarizability and is thus inapplicable for substances with a significant permanent dipole. It is applicable to gases such as N2, CO2, CH4 and H2 at sufficiently low densities and pressures. For example, the Clausius-Mossotti relation is accurate for N2 gas up to 1000 atm between 25 °C and 125 °C. Moreover, the Clausius-Mossotti relation may be applicable to substances if the applied electric field is at a sufficiently high frequencies such that any permanent dipole modes are inactive.
Clausius–Mossotti relation	Lorentz–Lorenz equation	The Lorentz–Lorenz equation is similar to the Clausius–Mossotti relation, except that it relates the refractive index (rather than the dielectric constant) of a substance to its polarizability. The Lorentz–Lorenz equation is named after the Danish mathematician and scientist Ludvig Lorenz, who published it in 1869, and the Dutch physicist Hendrik Lorentz, who discovered it independently in 1878. The most general form of the Lorentz–Lorenz equation is (in Gaussian-CGS units) n2−1n2+2=4π3Nαm where n is the refractive index, N is the number of molecules per unit volume, and αm is the mean polarizability. This equation is approximately valid for homogeneous solids as well as liquids and gases.
Clausius–Mossotti relation	Lorentz–Lorenz equation	When the square of the refractive index is n2≈1 , as it is for many gases, the equation reduces to: n2−1≈4πNαm or simply n−1≈2πNαm This applies to gases at ordinary pressures. The refractive index n of the gas can then be expressed in terms of the molar refractivity A as: n≈1+3ApRT where p is the pressure of the gas, R is the universal gas constant, and T is the (absolute) temperature, which together determine the number density N.
Multiview orthographic projection	Multiview orthographic projection	In technical drawing and computer graphics, a multiview projection is a technique of illustration by which a standardized series of orthographic two-dimensional pictures are constructed to represent the form of a three-dimensional object. Up to six pictures of an object are produced (called primary views), with each projection plane parallel to one of the coordinate axes of the object. The views are positioned relative to each other according to either of two schemes: first-angle or third-angle projection. In each, the appearances of views may be thought of as being projected onto planes that form a six-sided box around the object. Although six different sides can be drawn, usually three views of a drawing give enough information to make a three-dimensional object. These views are known as front view, top view and end view. Other names for these views include plan, elevation and section. When the plane or axis of the object depicted is not parallel to the projection plane, and where multiple sides of an object are visible in the same image, it is called an auxiliary view.
Multiview orthographic projection	Overview	To render each such picture, a ray of sight (also called a projection line, projection ray or line of sight) towards the object is chosen, which determines on the object various points of interest (for instance, the points that are visible when looking at the object along the ray of sight); those points of interest are mapped by an orthographic projection to points on some geometric plane (called a projection plane or image plane) that is perpendicular to the ray of sight, thereby creating a 2D representation of the 3D object.
Multiview orthographic projection	Overview	Customarily, two rays of sight are chosen for each of the three axes of the object's coordinate system; that is, parallel to each axis, the object may be viewed in one of 2 opposite directions, making for a total of 6 orthographic projections (or "views") of the object: Along a vertical axis (often the y-axis): The top and bottom views, which are known as plans (because they show the arrangement of features on a horizontal plane, such as a floor in a building).
Multiview orthographic projection	Overview	Along a horizontal axis (often the z-axis): The front and back views, which are known as elevations (because they show the heights of features of an object such as a building).
Multiview orthographic projection	Overview	Along an orthogonal axis (often the x-axis): The left and right views, which are also known as elevations, following the same reasoning.These six planes of projection intersect each other, forming a box around the object, the most uniform construction of which is a cube; traditionally, these six views are presented together by first projecting the 3D object onto the 2D faces of a cube, and then "unfolding" the faces of the cube such that all of them are contained within the same plane (namely, the plane of the medium on which all of the images will be presented together, such as a piece of paper, or a computer monitor, etc.). However, even if the faces of the box are unfolded in one standardized way, there is ambiguity as to which projection is being displayed by a particular face; the cube has two faces that are perpendicular to a ray of sight, and the points of interest may be projected onto either one of them, a choice which has resulted in two predominant standards of projection: First-angle projection: In this type of projection, the object is imagined to be in the first quadrant. Because the observer normally looks from the right side of the quadrant to obtain the front view, the objects will come in between the observer and the plane of projection. Therefore, in this case, the object is imagined to be transparent, and the projectors are imagined to be extended from various points of the object to meet the projection plane. When these meeting points are joined in order on the plane they form an image, thus in the first angle projection, any view is so placed that it represents the side of the object away from it. First angle projection is often used throughout parts of Europe so that it is often called European projection.
Multiview orthographic projection	Overview	Third-angle projection: In this type of projection, the object is imagined to be in the third quadrant. Again, as the observer is normally supposed to look from the right side of the quadrant to obtain the front view, in this method, the projection plane comes in between the observer and the object. Therefore, the plane of projection is assumed to be transparent. The intersection of this plan with the projectors from all the points of the object would form an image on the transparent plane.
Multiview orthographic projection	Primary views	Multiview projections show the primary views of an object, each viewed in a direction parallel to one of the main coordinate axes. These primary views are called plans and elevations. Sometimes they are shown as if the object has been cut across or sectioned to expose the interior: these views are called sections. Plan A plan is a view of a 3-dimensional object seen from vertically above (or sometimes below). It may be drawn in the position of a horizontal plane passing through, above, or below the object. The outline of a shape in this view is sometimes called its planform, for example with aircraft wings. The plan view from above a building is called its roof plan. A section seen in a horizontal plane through the walls and showing the floor beneath is called a floor plan. Elevation Elevation is the view of a 3-dimensional object from the position of a vertical plane beside an object. In other words, an elevation is a side view as viewed from the front, back, left or right (and referred to as a front elevation, [left/ right] side elevation, and a rear elevation). An elevation is a common method of depicting the external configuration and detailing of a 3-dimensional object in two dimensions. Building façades are shown as elevations in architectural drawings and technical drawings.
Multiview orthographic projection	Primary views	Elevations are the most common orthographic projection for conveying the appearance of a building from the exterior. Perspectives are also commonly used for this purpose. A building elevation is typically labeled in relation to the compass direction it faces; the direction from which a person views it. E.g. the North Elevation of a building is the side that most closely faces true north on the compass.Interior elevations are used to show details such as millwork and trim configurations.
Multiview orthographic projection	Primary views	In the building industry elevations are non-perspective views of the structure. These are drawn to scale so that measurements can be taken for any aspect necessary. Drawing sets include front, rear, and both side elevations. The elevations specify the composition of the different facades of the building, including ridge heights, the positioning of the final fall of the land, exterior finishes, roof pitches, and other architectural details.
Multiview orthographic projection	Primary views	Developed elevation A developed elevation is a variant of a regular elevation view in which several adjacent non-parallel sides may be shown together as if they have been unfolded. For example, the north and west views may be shown side-by-side, sharing an edge, even though this does not represent a proper orthographic projection. Section A section, or cross-section, is a view of a 3-dimensional object from the position of a plane through the object. A section is a common method of depicting the internal arrangement of a 3-dimensional object in two dimensions. It is often used in technical drawing and is traditionally crosshatched. The style of crosshatching often indicates the type of material the section passes through. With computed axial tomography, computers construct cross-sections from x-ray data.
Multiview orthographic projection	Auxiliary views	An auxiliary view or pictorial, is an orthographic view that is projected into any plane other than one of the six primary views. These views are typically used when an object has a surface in an oblique plane. By projecting into a plane parallel with the oblique surface, the true size and shape of the surface are shown. Auxiliary views are often drawn using isometric projection.
Multiview orthographic projection	Multiviews	Quadrants in descriptive geometry Modern orthographic projection is derived from Gaspard Monge's descriptive geometry. Monge defined a reference system of two viewing planes, horizontal H ("ground") and vertical V ("backdrop"). These two planes intersect to partition 3D space into 4 quadrants, which he labeled: I: above H, in front of V II: above H, behind V III: below H, behind V IV: below H, in front of VThese quadrant labels are the same as used in 2D planar geometry, as seen from infinitely far to the "left", taking H and V to be the X-axis and Y-axis, respectively.
Multiview orthographic projection	Multiviews	The 3D object of interest is then placed into either quadrant I or III (equivalently, the position of the intersection line between the two planes is shifted), obtaining first- and third-angle projections, respectively. Quadrants II and IV are also mathematically valid, but their use would result in one view "true" and the other view "flipped" by 180° through its vertical centerline, which is too confusing for technical drawings. (In cases where such a view is useful, e.g. a ceiling viewed from above, a reflected view is used, which is a mirror image of the true orthographic view.) Monge's original formulation uses two planes only and obtains the top and front views only. The addition of a third plane to show a side view (either left or right) is a modern extension. The terminology of quadrant is a mild anachronism, as a modern orthographic projection with three views corresponds more precisely to an octant of 3D space.
Multiview orthographic projection	Multiviews	First-angle projection In first-angle projection, the object is conceptually located in quadrant I, i.e. it floats above and before the viewing planes, the planes are opaque, and each view is pushed through the object onto the plane furthest from it. (Mnemonic: an "actor on a stage".) Extending to the 6-sided box, each view of the object is projected in the direction (sense) of sight of the object, onto the (opaque) interior walls of the box; that is, each view of the object is drawn on the opposite side of the box. A two-dimensional representation of the object is then created by "unfolding" the box, to view all of the interior walls. This produces two plans and four elevations. A simpler way to visualize this is to place the object on top of an upside-down bowl. Sliding the object down the right edge of the bowl reveals the right side view.
Multiview orthographic projection	Multiviews	Third-angle projection In third-angle projection, the object is conceptually located in quadrant III, i.e. it is positioned below and behind the viewing planes, the planes are transparent, and each view is pulled onto the plane closest to it. (Mnemonic: a "shark in a tank", esp. that is sunken into the floor.) Using the 6-sided viewing box, each view of the object is projected opposite to the direction (sense) of sight, onto the (transparent) exterior walls of the box; that is, each view of the object is drawn on the same side of the box. The box is then unfolded to view all of its exterior walls. A simpler way to visualize this is to place the object in the bottom of a bowl. Sliding the object up the right edge of the bowl reveals the right side view.
Multiview orthographic projection	Multiviews	Here is the construction of third angle projections of the same object as above. Note that the individual views are the same, just arranged differently.
Multiview orthographic projection	Multiviews	Additional information First-angle projection is as if the object were sitting on the paper and, from the "face" (front) view, it is rolled to the right to show the left side or rolled up to show its bottom. It is standard throughout Europe and Asia (excluding Japan). First-angle projection was widely used in the UK, but during World War II, British drawings sent to be manufactured in the USA, such as of the Rolls-Royce Merlin, had to be drawn in third-angle projection before they could be produced, e.g., as the Packard V-1650 Merlin. This meant that some British companies completely adopted third angle projection. BS 308 (Part 1) Engineering Drawing Practice, gave the option of using both projections, but generally, every illustration (other than the ones explaining the difference between first and third-angle) was done in first-angle. After the withdrawal of BS 308 in 1999, BS 8888 offered the same choice since it referred directly to ISO 5456-2, Technical drawings – Projection methods – Part 2: Orthographic representations.
Multiview orthographic projection	Multiviews	Third-angle is as if the object were a box to be unfolded. If we unfold the box so that the front view is in the center of the two arms, then the top view is above it, the bottom view is below it, the left view is to the left, and the right view is to the right. It is standard in the USA (ASME Y14.3-2003 specifies it as the default projection system), Japan (JIS B 0001:2010 specifies it as the default projection system), Canada, and Australia (AS1100.101 specifies it as the preferred projection system).
Multiview orthographic projection	Multiviews	Both first-angle and third-angle projections result in the same 6 views; the difference between them is the arrangement of these views around the box. Symbol A great deal of confusion has ensued in drafting rooms and engineering departments when drawings are transferred from one convention to another. On engineering drawings, the projection is denoted by an international symbol representing a truncated cone in either first-angle or third-angle projection, as shown by the diagram on the right. The 3D interpretation is a solid truncated cone, with the small end pointing toward the viewer. The front view is, therefore, two concentric circles. The fact that the inner circle is drawn with a solid line instead of dashed identifies this view as the front view, not the rear view. The side view is an isosceles trapezoid. In first-angle projection, the front view is pushed back to the rear wall, and the right side view is pushed to the left wall, so the first-angle symbol shows the trapezoid with its shortest side away from the circles. In third-angle projection, the front view is pulled forward to the front wall, and the right side view is pulled to the right wall, so the third-angle symbol shows the trapezoid with its shortest side towards the circles.
Multiview orthographic projection	Multiviews without rotation	Orthographic multiview projection is derived from the principles of descriptive geometry and may produce an image of a specified, imaginary object as viewed from any direction of space. Orthographic projection is distinguished by parallel projectors emanating from all points of the imaged object and which intersect of projection at right angles. Above, a technique is described that obtains varying views by projecting images after the object is rotated to the desired position.
Multiview orthographic projection	Multiviews without rotation	Descriptive geometry customarily relies on obtaining various views by imagining an object to be stationary and changing the direction of projection (viewing) in order to obtain the desired view.
Multiview orthographic projection	Multiviews without rotation	See Figure 1. Using the rotation technique above, note that no orthographic view is available looking perpendicularly at any of the inclined surfaces. Suppose a technician desired such a view to, say, look through a hole to be drilled perpendicularly to the surface. Such a view might be desired for calculating clearances or for dimensioning purposes. To obtain this view without multiple rotations requires the principles of Descriptive Geometry. The steps below describe the use of these principles in third angle projection.
Multiview orthographic projection	Multiviews without rotation	Fig.1: Pictorial of the imaginary object that the technician wishes to image. Fig.2: The object is imagined behind a vertical plane of projection. The angled corner of the plane of projection is addressed later. Fig.3: Projectors emanate parallel from all points of the object, perpendicular to the plane of projection. Fig.4: An image is created thereby. Fig.5: A second, horizontal plane of projection is added, perpendicular to the first. Fig.6: Projectors emanate parallel from all points of the object perpendicular to the second plane of projection. Fig.7: An image is created thereby. Fig.8: The third plane of projection is added, perpendicular to the previous two. Fig.9: Projectors emanate parallel from all points of the object perpendicular to the third plane of projection. Fig.10: An image is created thereby. Fig.11: The fourth plane of projection is added parallel to the chosen inclined surface, and perforce, perpendicular to the first (Frontal) plane of projection. Fig.12: Projectors emanate parallel from all points of the object perpendicularly from the inclined surface, and perforce, perpendicular to the fourth (Auxiliary) plane of projection. Fig.13: An image is created thereby. Fig.14-16: The various planes of projection are unfolded to be planar with the Frontal plane of projection. Fig.17: The final appearance of an orthographic multiview projection and which includes an "Auxiliary view" showing the true shape of an inclined surface.
Multiview orthographic projection	Territorial use	First-angle is used in most of the world.Third-angle projection is most commonly used in America, Japan (in JIS B 0001：2010); and is preferred in Australia, as laid down in AS 1100.101—1992 6.3.3.In the UK, BS8888 9.7.2.1 allows for three different conventions for arranging views: Labelled Views, Third Angle Projection, and First Angle Projection.
Manganese pentacarbonyl bromide	Manganese pentacarbonyl bromide	Manganese pentacarbonyl bromide is an organomanganese compound with the formula BrMn(CO)5. It is a bright orange solid that is a precursor to other manganese complexes. The compound is prepared by treatment of dimanganese decacarbonyl with bromine: Mn2(CO)10 + Br2 → 2 BrMn(CO)5The complex undergoes substitution by a variety of donor ligands (L), e.g. to give derivatives of the type BrMn(CO)3L2.
Manganese pentacarbonyl bromide	Manganese pentacarbonyl bromide	The complex adopts an octahedral coordination geometry.
Prostaglandin EP1 receptor	Prostaglandin EP1 receptor	Prostaglandin E2 receptor 1 (EP1) is a 42kDa prostaglandin receptor encoded by the PTGER1 gene. EP1 is one of four identified EP receptors, EP1, EP2, EP3, and EP4 which bind with and mediate cellular responses principally to prostaglandin E2) (PGE2) and also but generally with lesser affinity and responsiveness to certain other prostanoids (see Prostaglandin receptors). Animal model studies have implicated EP1 in various physiological and pathological responses. However, key differences in the distribution of EP1 between these test animals and humans as well as other complicating issues make it difficult to establish the function(s) of this receptor in human health and disease.
Prostaglandin EP1 receptor	Gene	The PTGER1 gene is located on human chromosome 19 at position p13.12 (i.e. 19p13.12), contains 2 introns and 3 exons, and codes for a G protein-coupled receptor (GPCR) of the rhodopsin-like receptor family, Subfamily A14 (see rhodopsin-like receptors#Subfamily A14).
Prostaglandin EP1 receptor	Expression	Studies in mice, rats, and guinea pigs have found EP1 Messenger RNA and protein to be expressed in the papillary collecting ducts of the kidney, in the kidney, lung, stomach, thalamus, and in the dorsal root ganglia neurons as well as several central nervous system sites. However, the expression of EP1 In humans, its expression appears to be more limited: EP1 receptors have been detected in human mast cells, pulmonary veins, keratinocytes, myometrium, and colon smooth muscle.
Prostaglandin EP1 receptor	Ligands	Activating ligands The following standard prostaglandins have the following relative potencies in binding to and activating EP1: PGE2≥PGE1>PGF2alpha>PGD2. The receptor binding affinity Dissociation constant Kd (i.e. ligand concentration needed to bind with 50% of available EP1 receptors) is ~20 nM and that of PGE1 ~40 for the mouse receptor and ~25 nM for PGE2 with the human receptor.Because PGE2 activates multiple prostanoid receptors and has a short half-life in vivo due to its rapidly metabolism in cells by omega oxidation and beta oxidation], metabolically resistant EP1-selective activators are useful for the study of EP1's function and could be clinically useful for the treatment of certain diseases. Only one such agonist that is highly selective in stimulating EP1 has been synthesized and identified, ONO-D1-OO4. This compound has a Ki inhibitory binding value (see Biochemistry#Receptor/ligand binding affinity) of 150 nM compared to that of 25 nM for PGE2 and is therefore ~5 times weaker than PGE2.
Prostaglandin EP1 receptor	Ligands	Inhibiting ligands SC51322 (Ki=13.8 nM), GW-848687 (Ki=8.6 nM), ONO-8711, SC-19220, SC-51089, and several other synthetic compounds given in next cited reference are selective competitive antagonists for EP1 that have been used for studies in animal models of human diseases. Carbacylin, 17-phenyltrinor PGE1, and several other tested compounds are dual EP1/EP3 antagonists (most marketed prostanoid receptor antagonists exhibit poor receptor selectivity).
Prostaglandin EP1 receptor	Mechanism of cell activation	When initially bound to PGE2 or other stimulating ligand, EP1 mobilizes G proteins containing the Gq alpha subunit (Gαq/11)-G beta-gamma complex. These two subunits in turn stimulate the Phosphoinositide 3-kinase pathway that raises cellular cytosolic Ca2+ levels thereby regulating Ca2+-sensitive cell signal pathways which include, among several others, those that promote the activation of certain protein kinase C isoforms. Since, this rise in cytosolic Ca2+ can also contract muscle cells, EP1 has been classified as a contractile type of prostanoid receptor. The activation of protein kinases C feeds back to phosphorylate and thereby desensitizes the activated EP1 receptor (see homologous desensitization but may also desensitize other types of prostanoid and non-prostanoid receptors (see heterologous desensitization). These desensitizations limit further EP1 receptor activation within the cell. Concurrently with the mobilization of these pathways, ligand-activated EP1 stimulates ERK, p38 mitogen-activated protein kinases, and CREB pathways that lead to cellular functional responses.
Prostaglandin EP1 receptor	Function	Studies using animals genetically engineered to lack EP1 and supplemented by studies using treatment with EP1 receptor antagonists and agonists indicate that this receptor serves several functions. 1) It mediates hyperalgesia due to EP11 receptors located in the central nervous system but suppresses pain perception due to E1 located on dorsal root ganglia neurons in rats. Thus, PGE2 causes increased pain perception when administered into the central nervous system but inhibits pain perception when administered systemically; 2) It promotes colon cancer development in Azoxymethane-induced and APC gene knockout mice. 3) It promotes hypertension in diabetic mice and spontaneously hypertensive rats. 4) It suppresses stress-induced impulsive behavior and social dysfunction in mice by suppressing the activation of Dopamine receptor D1 and Dopamine receptor D2 signaling. 5) It enhances the differentiation of uncommitted T cell lymphocytes to the Th1 cell phenotype and may thereby favor the development of inflammatory rather than allergic responses to immune stimulation in rodents. Studies with human cells indicate that EP1 serves a similar function on T cells. 6) It may reduce expression of Sodium-glucose transport proteins in the apical membrane or cells of the intestinal mucosa in rodents. 7) It may be differentially involved in etiology of acute brain injuries. Pharmacological inhibition or genetic deletion of EP1 receptor produce either beneficial or deleterious effects in rodent models of neurological disorders such as ischemic stroke, epileptic seizure, surgically induced brain injury and traumatic brain injury.
Prostaglandin EP1 receptor	Clinical studies	EP1 receptor antagonists have been studied clinically primarily to treat hyperalgesia. Numerous EP antagonists have been developed including SC51332, GW-848687X, a benzofuran-containing drug that have had some efficacy in treating various hyperalgesic syndromes in animal models. None have as yet been reported to be useful in humans.

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