Split (1)

train · 253k rows

page_content stringlengths 51 3.15k
Pi system Example Pi_system > Relationship to 𝜆-systems > The π-𝜆 theorem > Example This is the uniqueness statement of the Carathéodory extension theorem for finite measures. If this result does not seem very remarkable, consider the fact that it usually is very difficult or even impossible to fully describe every set in the 𝜎-algebra, and so the problem of equating measures would be completely hopeless without such a tool. Idea of the proof Define the collection of sets By the first assumption, μ 1 {\displaystyle \mu _{1}} and μ 2 {\displaystyle \mu _{2}} agree on I {\displaystyle I} and thus I ⊆ D .
Ionic potential Summary Ionic_potential In illite, the interlayer is totally collapsed because of the presence of the poorly hydrated K+. Ionic potential is also a measure of the polarising power of a cation. Ionic potential could be used as a general criterion for the selection of efficient adsorbents for toxic elements.
Logogen model Other models to consider Logogen_model > Other models to consider The person recognizes the word when you are left with a single choice; this is considered the "recognition point". checking model – This model was developed by Norris in 1986. In this particular model, he took the approach that any word that partially matches the input is analyzed and checked to see if it fits with the context of the situation.
Thelytokous parthenogenesis Summary Thelytoky Thelytoky (from the Greek thēlys "female" and tokos "birth") is a type of parthenogenesis and is the absence of mating and subsequent production of all female diploid offspring as for example in aphids. Thelytokous parthenogenesis is rare among animals and reported in about 1,500 species, about 1 in 1000 of described animal species, according to a 1984 study. It is more common in invertebrates, like arthropods, but it can occur in vertebrates, including salamanders, fish, and reptiles such as some whiptail lizards.
Online credentials for learning Digital credentials ecosystem Online_credentials_for_learning > History > Digital credentials ecosystem The digital credentials ecosystem is made up of a combination of traditional (better established) systems and flexible and dynamic (less regulated and new) systems. The challenge for the recognition of learning is that the pace of development, and also the point of departure, of these two aspects is different. The system is made up of seven interrelated sectors and groups of stakeholders, anchored to specific functions in the digital credentials environment. Use.
Combination Summary Combination In mathematics, a combination is a selection of items from a set that has distinct members, such that the order of selection does not matter (unlike permutations). For example, given three fruits, say an apple, an orange and a pear, there are three combinations of two that can be drawn from this set: an apple and a pear; an apple and an orange; or a pear and an orange. More formally, a k-combination of a set S is a subset of k distinct elements of S. So, two combinations are identical if and only if each combination has the same members. (The arrangement of the members in each set does not matter.)
Distributed Replicated Block Device Comparison to RAID-1 Distributed_Replicated_Block_Device > Comparison to RAID-1 DRBD bears a superficial similarity to RAID-1 in that it involves a copy of data on two storage devices, such that if one fails, the data on the other can be used. However, it operates in a very different way from RAID and even network RAID. In RAID, the redundancy exists in a layer transparent to the storage-using application. While there are two storage devices, there is only one instance of the application and the application is not aware of multiple copies.
Quantum Electrodynamics Interaction picture Quantum_electrodynamic > Mathematical formulation > Interaction picture This theory can be straightforwardly quantized by treating bosonic and fermionic sectors as free. This permits us to build a set of asymptotic states that can be used to start computation of the probability amplitudes for different processes. In order to do so, we have to compute an evolution operator, which for a given initial state \| i ⟩ {\displaystyle \|i\rangle } will give a final state ⟨ f \| {\displaystyle \langle f\|} in such a way to have: 5 This technique is also known as the S-matrix. The evolution operator is obtained in the interaction picture, where time evolution is given by the interaction Hamiltonian, which is the integral over space of the second term in the Lagrangian density given above:: 123 and so, one has: 86 where T is the time-ordering operator. This evolution operator only has meaning as a series, and what we get here is a perturbation series with the fine-structure constant as the development parameter. This series is called the Dyson series.
Delta function Approximations to the identity Dirac's_delta_function > Representations of the delta function > Approximations to the identity Typically a nascent delta function ηε can be constructed in the following manner. Let η be an absolutely integrable function on R of total integral 1, and define In n dimensions, one uses instead the scaling Then a simple change of variables shows that ηε also has integral 1. One may show that (5) holds for all continuous compactly supported functions f, and so ηε converges weakly to δ in the sense of measures. The ηε constructed in this way are known as an approximation to the identity.
Equation of motion Types Equations_of_motion > Types This is equivalent to saying an equation of motion in r is a second-order ordinary differential equation (ODE) in r, where t is time, and each overdot denotes one time derivative. The initial conditions are given by the constant values at t = 0, The solution r(t) to the equation of motion, with specified initial values, describes the system for all times t after t = 0. Other dynamical variables like the momentum p of the object, or quantities derived from r and p like angular momentum, can be used in place of r as the quantity to solve for from some equation of motion, although the position of the object at time t is by far the most sought-after quantity.
Artificial chemistry Important contributors Artificial_chemistry > Important contributors The first reference about Artificial Chemistries come from a Technical paper written by John McCaskill .Walter Fontana working with Leo Buss then took up the work developing the AlChemy model . The model was presented at the second International Conference of Artificial Life. In his first papers he presented the concept of organization, as a set of molecules that is algebraically closed and self-maintaining. This concept was further developed by Dittrich and Speroni di Fenizio into a theory of chemical organizations .Two main schools of artificial chemistries have been in Japan and Germany.
Blackmer gain cell Four-transistor Blackmer core Blackmer_gain_cell > Operation > Four-transistor Blackmer core The Blackmer circuit consists of two complementary log-antilog VCAs. Its four-transistor core – the Blackmer cell proper – combines two complementary current mirrors that are wired back-to-back and operate in a push-pull fashion. The lower NPN-type mirror (T1, T2) sinks input current I1; the upper PNP-type mirror (T3, T4) is sourcing input current I1 in the opposite direction. A VBE multiplier thermally coupled to the core maintains around 1.5 V (2 VBE) across its power supply terminals and regulates its idle current (2 mA or less in production monolithic ICs).
Symbolic Circuit Analysis Frequency domain expressions Symbolic_Circuit_Analysis > Frequency domain expressions In the frequency domain the most common task of symbolic circuit analysis is to obtain the relationship between input and output variables in the form of a rational function in the complex frequency s {\displaystyle {\mathit {s}}\,} and symbolic variables x {\displaystyle \mathbf {x} }: The above relationship is often called the network function. For physical systems, N ( s , x ) {\displaystyle N(s,\mathbf {x} )} and D ( s , x ) {\displaystyle D(s,\mathbf {x} )} are polynomials in s {\displaystyle {\mathit {s}}\,} with real coefficients: where z i ( x ) {\displaystyle z_{i}(\mathbf {x} )} are the zeroes and p i ( x ) {\displaystyle p_{i}(\mathbf {x} )} are the poles of the network function; m ⩾ n {\displaystyle m\geqslant n} . While there are several methods for generating coefficients a i ( x ) {\displaystyle a_{i}(\mathbf {x} )} and b i ( x ) {\displaystyle b_{i}(\mathbf {x} )} , no technique exists to obtain exact symbolic expressions for poles and zeroes for polynomials of order higher than 5.
Frances Arnold Research Frances_Arnold > Career > Research To circumvent this problem, she evolved the enzymes in the pathway to use NADH instead of NADPH, allowing for the production of isobutanol.Arnold has also used directed evolution to design highly specific and efficient enzymes that can be used as environmentally-friendly alternatives to some industrial chemical synthesis procedures. She, and others using her methods, have engineered enzymes that can carry out synthesis reactions more quickly, with fewer by-products, and in some cases eliminating the need for hazardous heavy metals.She uses structure-guided protein recombination to combine parts of different proteins to form protein chimeras with unique functions. She developed computational methods, such as SCHEMA, to predict how the parts can be combined without disrupting their parental structure, so that the chimeras will fold properly, and then applies directed evolution to further mutate the chimeras to optimize their functions.At Caltech, Arnold runs a laboratory that continues to study directed evolution and its applications in environmentally-friendly chemical synthesis and green/alternative energy, including the development of highly active enzymes (cellulolytic and biosynthetic enzymes) and microorganisms to convert renewable biomass to fuels and chemicals. A paper published in Science in 2019, with Inha Cho and Zhi-Jun Jia, has been retracted on January 2, 2020, as the results were found to be not reproducible.As of 2021, Arnold has an h-index of 135 according to Google Scholar.
Un sprung weight Effects Unsprung_mass > Effects If the vehicle does not have adequate wheel location in the vertical plane (such as a rear-wheel drive car with Hotchkiss drive, a live axle supported by simple leaf springs), vertical forces exerted by acceleration or hard braking combined with high unsprung mass can lead to severe wheel hop, compromising traction and steering control. A beneficial effect of unsprung mass is that high frequency road irregularities, such as the gravel in an asphalt or concrete road surface, are isolated from the body more completely because the tires and springs act as separate filter stages, with the unsprung mass tending to uncouple them. Likewise, sound and vibration isolation is improved (at the expense of handling), in production automobiles, by the use of rubber bushings between the frame and suspension, by any flexibility in the frame or body work, and by the flexibility of the seats.
Noise measurement Summary Noise_measurement Environmental noise monitoring is the measurement of noise in an outdoor environment caused by transport (e.g. motor vehicles, aircraft, and trains), industry (e.g. machines) and recreational activities (e.g. music). The laws and limits governing environmental noise monitoring differ from country to country. At the very least, noise may be annoying or displeasing or may disrupt the activity or balance of human or animal life, increasing levels of aggression, hypertension and stress.
Radio atmospheric signal Atmospheric noise Radio_atmospherics > Atmospheric noise The signal-to-noise ratio determines the sensibility and sensitivity of telecommunication systems (e.g., radio receivers). An analog signal must clearly exceed the noise amplitude in order to become detectable. Atmospheric noise is one of the most important sources for the limitation of the detection of radio signals. The steady electric discharging currents in a lightning channel cause a series of incoherent impulses in the whole frequency range, the amplitudes of which decreases approximately with the inverse frequency.
17 equal temperament Relation to 34-ET 17_equal_temperament > Interval size > Relation to 34-ET 17-ET is where every other step in the 34-ET scale is included, and the others are not accessible. Conversely 34-ET is a subdivision of 17-ET.
Plasmonic catalysis Mechanism Plasmonic_catalysis > Mechanism When a plasmon is generated, some electrons may have the energy to break completely free of the nanoparticle's electron shells. These highly excited electrons can then excite reactant electrons in the highest occupied molecular orbital or fill the lowest unoccupied molecular orbital, raising the energy of the molecule and allowing for a lower energy transition state. In most cases, these hot electrons do not find a reactant molecule to excite and instead fill the phonon and return to a ground state energy. The excess energy from the process is released as thermal energy, creating a localized temperature increase which can also increase the rate of reaction.
GNU Autotools Summary GNU_Build_System The GNU Autotools, also known as the GNU Build System, is a suite of programming tools designed to assist in making source code packages portable to many Unix-like systems. It can be difficult to make a software program portable: the C compiler differs from system to system; certain library functions are missing on some systems; header files may have different names; shared libraries may be compiled and installed in different ways. One way to handle platform differences is to write conditional code, with code blocks selected by means of preprocessor directives (#ifdef); but because of the wide variety of build environments this approach quickly becomes unmanageable.
Mitotic phase Summary Mitosis In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maintained. Therefore, mitosis is also known as equational division. In general, mitosis is preceded by S phase of interphase (during which DNA replication occurs) and is often followed by telophase and cytokinesis; which divides the cytoplasm, organelles and cell membrane of one cell into two new cells containing roughly equal shares of these cellular components.
Method of finite differences Use of derivatives Difference_machine > Initial values > Use of derivatives }}\ x^{n}} The same method of calculating the initial values from the coefficients can be used as for polynomial functions. The polynomial constant coefficients will now have the value a n ≡ f ( n ) ( 0 ) n ! {\displaystyle a_{n}\equiv {\frac {f^{(n)}(0)}{n!}}}
Multiplicative partitions of factorials Summary Multiplicative_partitions_of_factorials {\textstyle 5!} have lengths 4, 3 and 5. In other words, exactly one of the partitions of 5 !
Polynucleotide Prebiotic condensation of nucleobases with ribose Polynucleotide > Prebiotic condensation of nucleobases with ribose In order to understand how life arose, knowledge is required of the chemical pathways that permit formation of the key building blocks of life under plausible prebiotic conditions. According to the RNA world hypothesis free-floating ribonucleotides were present in the primitive soup. These were the fundamental molecules that combined in series to form RNA. Molecules as complex as RNA must have arisen from small molecules whose reactivity was governed by physico-chemical processes.
Student-t distribution In frequentist statistical inference Student_t-distribution > Uses > In frequentist statistical inference Student's t-distribution arises in a variety of statistical estimation problems where the goal is to estimate an unknown parameter, such as a mean value, in a setting where the data are observed with additive errors. If (as in nearly all practical statistical work) the population standard deviation of these errors is unknown and has to be estimated from the data, the t-distribution is often used to account for the extra uncertainty that results from this estimation. In most such problems, if the standard deviation of the errors were known, a normal distribution would be used instead of the t-distribution. Confidence intervals and hypothesis tests are two statistical procedures in which the quantiles of the sampling distribution of a particular statistic (e.g. the standard score) are required.
Discovery and development of gliflozins SGLT-2 protein Discovery_and_development_of_gliflozins > Introduction > SGLT-2 protein Sodium/glucose co-transporter (SGLT) proteins are bound to the cell membrane and have the role of transporting glucose through the membrane into the cells, against the concentration gradient of glucose. This is done by using the sodium gradient, produced by sodium/potassium ATPase pumps, so at the same time glucose is transported into the cells, the sodium is too. Since it is against the gradient, it requires energy to work. SGLT proteins cause the glucose reabsorption from the glomerular filtrate, independent of insulin.SGLT-2 is a member of the glucose transporter family and is a low-affinity, high-capacity glucose transporter.
List of uncertainty propagation software Software List_of_uncertainty_propagation_software > Software UncertaintyWrapper is a free and open source software Python package that propagates uncertainty using 1st order linear combinations. Covariance is also propagated. It approximates sensitivity with finite central differences.
Positive pressure breathing Carbon dioxide toxicity Diving_physiology > Breathing under pressure > Hyperbaric gas toxicity > Carbon dioxide toxicity Inadequate ventilatory response to exertion was indicated by the fact that, despite resting values in the normal range, end tidal carbon dioxide rose markedly with exertion even when the divers breathed air at a depth of only a few feet.Carbon dioxide is not expelled completely when the diver exhales into apparatus with mechanical dead space, such as a snorkel, full face diving mask, or diving helmet, and then inhales from the dead space.In closed circuit or semi-closed circuit rebreather diving, exhaled carbon dioxide must be removed from the breathing system, usually by a scrubber containing a solid chemical compound with a high affinity for CO2, such as soda lime. If not removed from the system, it will cause an increase in the inhaled concentration, known as scrubber breakthrough. When the diver exercises at a higher level of exertion, more carbon dioxide is produced due to elevated metabolic activity.
Memory consolidation Summary Memory_consolidation The first, synaptic consolidation, which is thought to correspond to late-phase long-term potentiation, occurs on a small scale in the synaptic connections and neural circuits within the first few hours after learning. The second process is systems consolidation, occurring on a much larger scale in the brain, rendering hippocampus-dependent memories independent of the hippocampus over a period of weeks to years. Recently, a third process has become the focus of research, reconsolidation, in which previously consolidated memories can be made labile again through reactivation of the memory trace.
Responsive computer-aided design Summary Responsive_computer-aided_design These relationships are then linked to physical sensors, allowing them to drive changes to the CAD model within the established parameters. Reasons to allow sensors to modify a CAD model include customizing a design to fit a user's anthropometry, assisting people without CAD skills to personalize a design, or automating part of an iterative design process in similar fashion to generative design. Once the sensors have affected the design it may then be manufactured as a one-off piece using a digital fabrication technology, or go through further development by a designer.
Middleware (distributed applications) Use Metacomputing_software > Use Middleware services provide a more functional set of application programming interfaces to allow an application to: Locate transparently across the network, thus providing interaction with another service or application Filter data to make them friendly usable or public via anonymization process for privacy protection (for example) Be independent from network services Be reliable and always available Add complementary attributes like semanticswhen compared to the operating system and network services. Middleware offers some unique technological advantages for business and industry. For example, traditional database systems are usually deployed in closed environments where users access the system only via a restricted network or intranet (e.g., an enterprise’s internal network). With the phenomenal growth of the World Wide Web, users can access virtually any database for which they have proper access rights from anywhere in the world.
Alternation of generations A complex life cycle Alternation_of_generation > Alternation of generations in plants > A complex life cycle Later the seed is shed, germinates and grows into a mature tree. A 'male' willow tree (a microsporophyte) produces flowers with only stamens, the anthers of which are the microsporangia. Microspores germinate producing microgametophytes; at maturity one or more antheridia are produced.
Functional programming language Strict versus non-strict evaluation Functional_language > Concepts > Strict versus non-strict evaluation Functional languages can be categorized by whether they use strict (eager) or non-strict (lazy) evaluation, concepts that refer to how function arguments are processed when an expression is being evaluated. The technical difference is in the denotational semantics of expressions containing failing or divergent computations. Under strict evaluation, the evaluation of any term containing a failing subterm fails. For example, the expression: print length() fails under strict evaluation because of the division by zero in the third element of the list.
Signing space Summary Signing_space Signing space is the space used by a signer using a sign language. It's the three-dimensional space in front of the signer, from the waist to the forehead and from one side of the body to the other, where signs can be realized. Signers use this space to represent physical space and to represent conceptual structure. Locations in a signing space are mapped to locations in the real space.
Fuel economy in automobiles Energy considerations Gasoline_consumption > Energy considerations More modern designs improve fuel efficiency by only activating the power assistance when needed; this is done by using either direct electrical power steering assistance or an electrically powered hydraulic pump. Cooling. The older cooling systems used a constantly engaged mechanical fan to draw air through the radiator at a rate directly related to the engine speed.
Inner moon Orbits Inner_moon > Orbits Naiad, Neptune's closest moon, is the exception, being inclined at 4.75° to Neptune's equator. The innermost satellites orbit within the planetary rings, well within the fluid Roche limit, and only the internal strength and friction of their materials prevents them from being torn apart by tidal forces. This means that, if a pebble were placed in the part of the satellite furthest away from the planet, the tidal force outward is stronger than the satellite's gravity planetward, so the pebble would fall upward.
Industrial electronics Summary Power_electronic_applications Power electronics is the application of electronics to the control and conversion of electric power. The first high-power electronic devices were made using mercury-arc valves. In modern systems, the conversion is performed with semiconductor switching devices such as diodes, thyristors, and power transistors such as the power MOSFET and IGBT.
Grand Unified Theory Proposed theories GUT_theories > Proposed theories Several theories have been proposed, but none is currently universally accepted. An even more ambitious theory that includes all fundamental forces, including gravitation, is termed a theory of everything. Some common mainstream GUT models are: Pati–Salam model — SU(4) × SU(2) × SU(2) Georgi–Glashow model — SU(5); and Flipped SU(5) — SU(5) × U(1) SO(10) model; and Flipped SO(10) — SO(10) × U(1) E6 model; and Trinification — SU(3) × SU(3) × SU(3) minimal left-right model — SU(3)C × SU(2)L × SU(2)R × U(1)B − L 331 model — SU(3)C × SU(3)L × U(1)X chiral colorNot quite GUTs: Note: These models refer to Lie algebras not to Lie groups. The Lie group could be / Z 2 , {\displaystyle /\mathbb {Z} _{2},} just to take a random example.
Electrical system design Design Electrical_system_design > Design Except for one-line diagrams, this should show all the circuit nodes. One-line diagrams represent the three or four conductors of three-phase power circuits with one line.
Basement rock Complexity Basement_rocks > Complexity New igneous rock may freshly intrude into the crust from underneath, or may form underplating, where the new igneous rock forms a layer on the underside of the crust. The majority of continental crust on the planet is around 1 to 3 billion years old, and it is theorised that there was at least one period of rapid expansion and accretion to the continents during the Precambrian. Much of the basement rock may have originally been oceanic crust, but it was highly metamorphosed and converted into continental crust. It is possible for oceanic crust to be subducted down into the Earth's mantle, at subduction fronts, where oceanic crust is being pushed down into the mantle by an overriding plate of oceanic or continental crust.
Biological functions of nitric oxide Immune response Biological_functions_of_nitric_oxide > Immune response Nitric oxide is generated by phagocytes (monocytes, macrophages, and neutrophils) as part of the human immune response. Phagocytes are armed with inducible nitric oxide synthase (iNOS), which is activated by interferon-gamma (IFN-γ) as a single signal or by tumor necrosis factor (TNF) along with a second signal. On the other hand, transforming growth factor-beta (TGF-β) provides a strong inhibitory signal to iNOS, whereas interleukin-4 (IL-4) and IL-10 provide weak inhibitory signals.
Multiclass classification Support vector machines Multiclass_classifier > General strategies > Extension from binary > Support vector machines Support vector machines are based upon the idea of maximizing the margin i.e. maximizing the minimum distance from the separating hyperplane to the nearest example. The basic SVM supports only binary classification, but extensions have been proposed to handle the multiclass classification case as well. In these extensions, additional parameters and constraints are added to the optimization problem to handle the separation of the different classes.
Pyroptosis Caspase-3-dependent cell death pathway Pyroptosis > Mechanism > Caspase-3-dependent cell death pathway GSDME is then activated by caspase-3 to form pores on the cell membrane. It has also been found that GSDME can permeabilise mitochondrial membranes to release cytochrome c, which further activates caspase-3 and accelerates GSDME cleavage. This positive feedback loop ensures that programmed cell death is carried forward.
History of computer science Alan Turing and the Turing machine History_of_computer_science > Emergence of a discipline > Alan Turing and the Turing machine These computers were able to perform the calculations that were performed by the previous human clerks. Since the values stored by digital machines were not bound to physical properties like analog devices, a logical computer, based on digital equipment, was able to do anything that could be described "purely mechanical." The theoretical Turing Machine, created by Alan Turing, is a hypothetical device theorized in order to study the properties of such hardware.
NFAT As a drug target NFAT > As a drug target Due to its essential role in the production of the T cell proliferative cytokine IL-2, NFAT signalling is an important pharmacological target for the induction of immunosuppression. CN inhibitors, which prevent the activation of NFAT, including CsA and tacrolimus (FK506), are used in the treatment of rheumatoid arthritis, multiple sclerosis, Crohn's disease, and ulcerative colitis and to prevent the rejection of organ transplants. However, there is a toxicity associated with these drugs due to their ability to inhibit CN in non-immune cells, which limits their use in other situations that may call for immunosuppressing drug therapy, including allergy and inflammation.
Immature ovum Ootid Immature_ovum > Ootid Thus, there are 23 chromatids in total (1N). In other words, the ootid is the immature ovum formed shortly after fertilization, but before complete maturation into an ovum. Thus, the time spent as an ootid is measured in minutes.
Uniform scaling Summary Scaling_matrix It also includes the case in which one or more scale factors are equal to zero (projection), and the case of one or more negative scale factors (a directional scaling by -1 is equivalent to a reflection). Scaling is a linear transformation, and a special case of homothetic transformation (scaling about a point). In most cases, the homothetic transformations are non-linear transformations.
Physician assistant Scope of practice (Canada) Physician_assistant > Jurisdictions > Canada > Scope of practice (Canada) As of 2023 PAs in Canada may: Physician assistants resemble and provide many of the functions of Physician Assistants (PA) are academically prepared and highly skilled health care professionals who provide a broad range of medical services. PAs are physician extenders and not independent practitioners; they work with a degree of autonomy, negotiated and agreed on by the supervising physician(s) and the PA. PAs can work in any clinical setting to extend physician services. PAs complement existing services and aid in improving patient access to health care.
Himyaritic language Linguistic features Himyaritic_language > Linguistic features Stein leaves open the question that perhaps due to the writing style the expression of definiteness was normally left out, and that the usage of /ʔam-/ in the oral poetry of speakers of various Yemeni Arabic dialects might ultimately be of ancient origin.Furthermore, the suffixes of the perfect (suffix conjugation) in the first person singular and the second person began with /-k-/, while most varieties of Arabic have /-t-/. This feature is also found in Sayhadic, Afrosemitic and Modern South Arabian.
Innate resistance to HIV Summary Innate_resistance_to_HIV A small proportion of humans show partial or apparently complete innate resistance to HIV, the virus that causes AIDS. The main mechanism is a mutation of the gene encoding CCR5, which acts as a co-receptor for HIV. It is estimated that the proportion of people with some form of resistance to HIV is under 10%.
Premature ventricular contraction Treatment Premature_ventricular_contractions > Treatment Beta blockers: do not directly affect or reduce the occurrence of PVCs, but reduce cardiac contractility which makes PVCs less obvious to a person; possibly reduce catecholamine induced PVCs (in catecholamine-sensitive people) due to adrenaline not reaching sinus node as much. Calcium channel blockers Electrolytes replacement Magnesium supplements (e.g. magnesium citrate, orotate, Maalox, etc.) Potassium supplements (e.g. chloride potassium with citrate ion) Radiofrequency catheter ablation treatment.
Maclaurin series Generalization Taylor_coefficient > Approximation error and convergence > Generalization Hence, f ( a + t ) = lim h → 0 + ∫ − ∞ ∞ f ( a + x ) d P t / h , h ( x ) . {\displaystyle f(a+t)=\lim _{h\to 0^{+}}\int _{-\infty }^{\infty }f(a+x)dP_{t/h,h}(x).} The law of large numbers implies that the identity holds.
Cytochrome C Extramitochondrial localisation Cytochrome_C > Extramitochondrial localisation Cytochrome c is widely believed to be localised solely in the mitochondrial intermembrane space under normal physiological conditions. The release of cytochrome c from mitochondria to the cytosol, where it activates the caspase family of proteases, is believed to be the primary trigger leading to the onset of apoptosis. Measuring the amount of cytochrome c leaking from mitochondria to cytosol, and out of the cell to culture medium, is a sensitive method to monitor the degree of apoptosis. However, detailed immuno-electronmicroscopic studies with rat tissues sections employing cytochrome c specific antibodies provide compelling evidence that cytochrome c under normal cellular conditions is also present at extramitochondrial locations.
Double Pendulum Analysis and interpretation Double_Pendulum > Analysis and interpretation Several variants of the double pendulum may be considered; the two limbs may be of equal or unequal lengths and masses, they may be simple pendulums or compound pendulums (also called complex pendulums) and the motion may be in three dimensions or restricted to the vertical plane. In the following analysis, the limbs are taken to be identical compound pendulums of length l and mass m, and the motion is restricted to two dimensions. In a compound pendulum, the mass is distributed along its length. If the mass is evenly distributed, then the center of mass of each limb is at its midpoint, and the limb has a moment of inertia of I = 1/12ml2 about that point.
Lie Groups Representations Real_Lie_group > Representations One important aspect of the study of Lie groups is their representations, that is, the way they can act (linearly) on vector spaces. In physics, Lie groups often encode the symmetries of a physical system. The way one makes use of this symmetry to help analyze the system is often through representation theory. Consider, for example, the time-independent Schrödinger equation in quantum mechanics, H ^ ψ = E ψ {\displaystyle {\hat {H}}\psi =E\psi } .
Hyl (unit) Summary Hyl_(unit) The gravitational metric system (original French term Système des Méchaniciens) is a non-standard system of units, which does not comply with the International System of Units (SI). It is built on the three base quantities length, time and force with base units metre, second and kilopond respectively. Internationally used abbreviations of the system are MKpS, MKfS or MKS (from French mètre–kilogramme-poids–seconde or mètre–kilogramme-force–seconde). However, the abbreviation MKS is also used for the MKS system of units, which, like the SI, uses mass in kilogram as a base unit.
Receptive fields In the context of neural networks Receptive_fields > In the context of neural networks There are a lot of ways that one can increase the receptive field on a CNN. When used in this sense, the term adopts a meaning reminiscent of receptive fields in actual biological nervous systems. CNNs have a distinct architecture, designed to mimic the way in which real animal brains are understood to function; instead of having every neuron in each layer connect to all neurons in the next layer (Multilayer perceptron), the neurons are arranged in a 3-dimensional structure in such a way as to take into account the spatial relationships between different neurons with respect to the original data.
Lone pair Summary Lone_electron_pair In chemistry, a lone pair refers to a pair of valence electrons that are not shared with another atom in a covalent bond and is sometimes called an unshared pair or non-bonding pair. Lone pairs are found in the outermost electron shell of atoms. They can be identified by using a Lewis structure.
Escherichia virus CC31 Genetic modification Escherichia_virus_CC31 > Genome > Genetic modification This results in horizontal gene transfer between the virus and cell, resulting in the evolution of the virus and the bacterium. The viral DNA also develops minute deletions, immunity regions, and silent genetic regions due to the non-homologous binding of the DNA. These change in virus' genetic material can either inhibit or promote future replication.
Internet area network Summary Internet_area_network An Internet area network (IAN) is a concept for a communications network that connects voice and data endpoints within a cloud environment over IP, replacing an existing local area network (LAN), wide area network (WAN) or the public switched telephone network (PSTN).
Choppy waves Wave conditions for surfing Surf_wave > The physics of surfing > Wave conditions for surfing Therefore, more experience is required to catch low peel angle waves. More experienced surfers can handle longer section lengths, increased velocities, and higher wave heights. Different locations offer different types of surfing conditions for each skill level.
Mobile membranes Summary Mobile_membranes Mobile membranes represent a variant of membrane systems inspired by the biological movements given by endocytosis and exocytosis. They have the expressive power of both P systems and process calculi with mobility such as mobile ambients and brane calculi .
Characteristic vector analysis Software/source code Principal_components > Software/source code MATLAB - The SVD function is part of the basic system. In the Statistics Toolbox, the functions princomp and pca (R2012b) give the principal components, while the function pcares gives the residuals and reconstructed matrix for a low-rank PCA approximation. Matplotlib – Python library have a PCA package in the .mlab module.
Strain rate imaging Curves Strain_rate_imaging > Display > Curves The most common way is by displaying curves of the strain and strain rate, typically the time course during one heart cycle. Each curve will then represent the deformation in one region of the myocardium, but acquisition of a full sector allows display of multiple curves simultaneously in the same image for comparison.
Electric heat Summary Electric_heater The heating element inside every electric heater is an electrical resistor, and works on the principle of Joule heating: an electric current passing through a resistor will convert that electrical energy into heat energy. Most modern electric heating devices use nichrome wire as the active element; the heating element, depicted on the right, uses nichrome wire supported by ceramic insulators. Alternatively, a heat pump can achieve around 150% - 600% efficiency for heating, or COP 1.5 - 6.0 Coefficient of performance, because it uses electric power only for transferring existing thermal energy.
Stack machine Stack storage Stack_machines > Design > Stack storage Except for explicit "load from memory" instructions, the order of operand usage is identical with the order of the operands in the data stack, so excellent prefetching can be accomplished easily. Consider X+1. It compiles to Load X; Load 1; Add.
Transcendent angle Complex values Transcendent_angle > Complex values Likewise, extended to the whole complex plane, w ↦ z = gd − 1 ⁡ w {\textstyle w\mapsto z=\operatorname {gd} ^{-1}w} is a periodic function of period 2 π {\textstyle 2\pi } which sends any infinite strip of "width" 2 π {\textstyle 2\pi } onto the strip − π < Im ⁡ z ≤ π . {\textstyle -\pi <\operatorname {Im} z\leq \pi .} For all points in the complex plane, these functions can be correctly written as: gd ⁡ z = 2 arctan ( tanh ⁡ 1 2 z ) , gd − 1 ⁡ w = 2 artanh ( tan ⁡ 1 2 w ) .
Fas receptor Function Fas_receptor > Function Active caspase-8 is then released from the DISC into the cytosol, where it cleaves other effector caspases, eventually leading to DNA degradation, membrane blebbing, and other hallmarks of apoptosis. Recently, Fas has also been shown to promote tumor growth, since during tumor progression, it is frequently downregulated or cells are rendered apoptosis resistant. Cancer cells in general, regardless of their Fas apoptosis sensitivity, depend on constitutive activity of Fas.
Bidentate ligand Strong field and weak field ligands Ligand > Strong field and weak field ligands Metal ions bound to strong-field ligands follow the Aufbau principle, whereas complexes bound to weak-field ligands follow Hund's rule. Binding of the metal with the ligands results in a set of molecular orbitals, where the metal can be identified with a new HOMO and LUMO (the orbitals defining the properties and reactivity of the resulting complex) and a certain ordering of the 5 d-orbitals (which may be filled, or partially filled with electrons). In an octahedral environment, the 5 otherwise degenerate d-orbitals split in sets of 3 and 2 orbitals (for a more in-depth explanation, see crystal field theory): 3 orbitals of low energy: dxy, dxz and dyz and 2 orbitals of high energy: dz2 and dx2−y2.The energy difference between these 2 sets of d-orbitals is called the splitting parameter, Δo.
Catastrophic interference Self-refreshing memory Catastrophic_interference > Proposed solutions > Rehearsal > Self-refreshing memory Inspired by and independently of Ans and Rousset (1997) also proposed a two-network artificial neural architecture with memory self-refreshing that overcomes catastrophic interference when sequential learning tasks are carried out in distributed networks trained by backpropagation. The principle is to learn new external patterns concurrently with internally generated pseudopatterns, or 'pseudo-memories', that reflect the previously learned information. What mainly distinguishes this model from those that use classical pseudorehearsal in feedforward multilayer networks is a reverberating process that is used for generating pseudopatterns. After a number of activity re-injections from a single random seed, this process tends to go up to nonlinear network attractors that are more suitable for capturing optimally the deep structure of knowledge distributed within connection weights than the single feedforward pass of activity used in pseudo-rehearsal. The memory self-refreshing procedure turned out to be very efficient in transfer processes and in serial learning of temporal sequences of patterns without catastrophic forgetting.
Proportion (mathematics) History Proportion_(mathematics) > History A Greek mathematician Eudoxus provided a definition for the meaning of the equality between two ratios. This definition of proportion forms the subject of Euclid's Book V, where we can read: Magnitudes are said to be in the same ratio, the first to the second and the third to the fourth when, if any equimultiples whatever be taken of the first and third, and any equimultiples whatever of the second and fourth, the former equimultiples alike exceed, are alike equal to, or alike fall short of, the latter equimultiples respectively taken in corresponding order. Later, the realization that ratios are numbers allowed to switch from solving proportions to equations, and from transformation of proportions to algebraic transformations.
Parallel breadth-first search Direction optimization Parallel_breadth-first_search > Parallel BFS with distributed memory > Implementation optimization strategies > Direction optimization Compared to the top-down BFS, bottom-up BFS reduces the fail checking by self-examining the parent to prevent contention. However, bottom-up BFS requires serializing work of one vertex and only works better when a large fraction of vertices are in the frontier. As a result, a direction optimized BFS should combine the top-down and the bottom-up BFS. More accurately, the BFS should start with the top-down direction, switch to the bottom-up BFS when the number of vertex exceeds a given threshold and vice versa.
Mathematical symbol Equality, equivalence and similarity Mathematical_symbols > Equality, equivalence and similarity In probability and statistics, may specify the probability distribution of a random variable. For example, X ∼ N ( 0 , 1 ) {\displaystyle X\sim N(0,1)} means that the distribution of the random variable X is standard normal. 6.
Developmental geneticist Cell differentiation Biological_development > Developmental processes > Cell differentiation Typically their chromatin structure is very open, allowing access for the transcription enzymes, and specific transcription factors bind to regulatory sequences in the DNA in order to activate gene expression. For example, NeuroD is a key transcription factor for neuronal differentiation, myogenin for muscle differentiation, and HNF4 for hepatocyte differentiation. Cell differentiation is usually the final stage of development, preceded by several states of commitment which are not visibly differentiated.
Declarative knowledge Value Declarative_knowledge > Value However, it is often difficult to assess the value of knowledge if one does not foresee a situation where it would be useful. In this regard, it can happen that the value of apparently useless knowledge is only discovered much later. For example, Maxwell's equations linking magnetism to electricity were considered useless at the time of discovery until experimental scientists discovered how to detect electromagnetic waves. Occasionally, knowledge may have a negative value, for example, when it hinders someone to do what would be needed because their knowledge of associated dangers paralyzes them.
Media synthesis Rise of artificial intelligence Media_synthesis_(AI) > History > Rise of artificial intelligence Then he used a change algorithm to modify the network's input parameters. The network was able to randomly generate new music in a highly uncontrolled manner.In 2014, Ian Goodfellow and his colleagues developed a new class of machine learning systems: generative adversarial networks (GAN).
Alveolar-arterial gradient Summary Alveolar-arterial_gradient As a rule, PAO2 is always higher than PaO2 by at least 5–10 mmHg, even in a healthy person with normal ventilation and perfusion. This gradient exists due to both physiological right-to-left shunting and a physiological V/Q mismatch caused by gravity-dependent differences in perfusion to various zones of the lungs. The bronchial vessels deliver nutrients and oxygen to certain lung tissues, and some of this spent, deoxygenated venous blood drains into the highly oxygenated pulmonary veins, causing a right-to-left shunt.
Square root of –1 Cube roots Square_root_of_−1 > Properties > Cube roots The three cube roots of i are: − i , {\displaystyle -i,} 3 2 + i 2 , {\displaystyle {\frac {\sqrt {3}}{2}}+{\frac {i}{2}},} and − 3 2 + i 2 . {\displaystyle -{\frac {\sqrt {3}}{2}}+{\frac {i}{2}}.} Similar to all the roots of 1, all the roots of i are the vertices of regular polygons, which are inscribed within the unit circle in the complex plane.
Constructible numbers Summary Constructible_number In geometry and algebra, a real number r {\displaystyle r} is constructible if and only if, given a line segment of unit length, a line segment of length \| r \| {\displaystyle \|r\|} can be constructed with compass and straightedge in a finite number of steps. Equivalently, r {\displaystyle r} is constructible if and only if there is a closed-form expression for r {\displaystyle r} using only integers and the operations for addition, subtraction, multiplication, division, and square roots. The geometric definition of constructible numbers motivates a corresponding definition of constructible points, which can again be described either geometrically or algebraically.
Ornstein theory Discussion Ornstein_isomorphism_theorem > Discussion The fifth theorem states that there is a single, unique flow (up to a constant rescaling of time) that has infinite entropy. The phrase "up to a constant rescaling of time" means simply that if T t {\displaystyle T_{t}} and S t {\displaystyle S_{t}} are two Bernoulli flows with the same entropy, then S t = T c t {\displaystyle S_{t}=T_{ct}} for some constant c. The developments also included proofs that factors of Bernoulli shifts are isomorphic to Bernoulli shifts, and gave criteria for a given measure-preserving dynamical system to be isomorphic to a Bernoulli shift. A corollary of these results is a solution to the root problem for Bernoulli shifts: So, for example, given a shift T, there is another shift T {\displaystyle {\sqrt {T}}} that is isomorphic to it.
Surface second harmonic generation Summary Surface_second_harmonic_generation Since centrosymmetric symmetry in centrosymmetric media is only disrupted in the first (occasionally second and third) atomic or molecular layer of a system, properties of the second harmonic signal then provide information about the surface atomic or molecular layers only. Surface SHG is possible even for materials which do not exhibit SHG in the bulk. Although in many situations the dominant second harmonic signal arises from the broken symmetry at the surface, the signal in fact always has contributions from both the surface and bulk. Thus, the most sensitive experiments typically involve modification of a surface and study of the subsequent modification of the harmonic generation properties.
State variables Control systems engineering State_variables > Control systems engineering In control engineering and other areas of science and engineering, state variables are used to represent the states of a general system. The set of possible combinations of state variable values is called the state space of the system. The equations relating the current state of a system to its most recent input and past states are called the state equations, and the equations expressing the values of the output variables in terms of the state variables and inputs are called the output equations. As shown below, the state equations and output equations for a linear time invariant system can be expressed using coefficient matrices: A, B, C, and D A ∈ R N × N , B ∈ R N × L , C ∈ R M × N , D ∈ R M × L , {\displaystyle A\in \mathbb {R} ^{N\times N},\quad B\in \mathbb {R} ^{N\times L},\quad C\in \mathbb {R} ^{M\times N},\quad D\in \mathbb {R} ^{M\times L},} where N, L and M are the dimensions of the vectors describing the state, input and output, respectively.
Path integral Monte Carlo Summary Path_integral_Monte_Carlo Path integral Monte Carlo (PIMC) is a quantum Monte Carlo method used to solve quantum statistical mechanics problems numerically within the path integral formulation. The application of Monte Carlo methods to path integral simulations of condensed matter systems was first pursued in a key paper by John A. Barker.The method is typically (but not necessarily) applied under the assumption that symmetry or antisymmetry under exchange can be neglected, i.e., identical particles are assumed to be quantum Boltzmann particles, as opposed to fermion and boson particles. The method is often applied to calculate thermodynamic properties such as the internal energy, heat capacity, or free energy.
Vibration fatigue Random load description Vibration_fatigue > Vibration-fatigue-life estimation > Random load description In a random process, the amplitude can not be described as a function of time, because of its probabilistic nature. However, certain statistical properties can be extracted from a signal sample, representing a realization of a random process, provided the latter is ergodic. An important characteristics for the field of vibration fatigue is the amplitude probability density function, that describes the statistical distribution of peak amplitudes. Ideally, the probability of cycle amplitudes, describing the load severity, could then be deduced directly. However, as this is not always possible, the sought-after probability is often estimated empirically.
Parenteral medication Classification Oral_drug > Classification Routes of administration are usually classified by application location (or exposition). The route or course the active substance takes from application location to the location where it has its target effect is usually rather a matter of pharmacokinetics (concerning the processes of uptake, distribution, and elimination of drugs). Exceptions include the transdermal or transmucosal routes, which are still commonly referred to as routes of administration. The location of the target effect of active substances are usually rather a matter of pharmacodynamics (concerning e.g. the physiological effects of drugs). An exception is topical administration, which generally means that both the application location and the effect thereof is local.Topical administration is sometimes defined as both a local application location and local pharmacodynamic effect, and sometimes merely as a local application location regardless of location of the effects.
PC12 cells Differentiation PC12_cell > Differentiation Their embryological origin with neuroblastic cells means they can easily differentiate into neuron-like cells even though they are not considered adult neurons. Neuron-like means they share properties similar to neurons, in this case it is referring to releasing neurotransmitter by vesicles. PC12 cells stop dividing and terminally differentiate when treated with nerve growth factor or dexamethasone. This makes PC12 cells useful as a model system for neuronal differentiation and neurosecretion.
Aerodynamic ceiling Aerodynamic basis Aerodynamic_ceiling > Aerodynamic basis Consideration of statics shows that when a fixed-wing aircraft is in straight, level flight at constant-airspeed, the lift on the main wing plus the force (in the negative sense if downward) on the horizontal stabilizer is equal to the aircraft's weight and its thrust is equal to its drag. In most circumstances this equilibrium can occur at a range of airspeeds. The minimum such speed is the stall speed, or VSO.
Chromosome instability Genome integrity Chromosome_instability > Genome integrity However, chromosomal instability syndromes such as Bloom syndrome, ataxia telangiectasia and Fanconi anaemia are inherited and are considered to be genetic diseases. These disorders are associated with tumor genesis, but often have a phenotype on the individuals as well. The genes that control chromosome instability are known as chromosome instability genes and they control pathways such as mitosis, DNA replication, repair and modification. They also control transcription, and process nuclear transport.
P (complexity) Relationships to other classes Complexity_class_P > Relationships to other classes A generalization of P is NP, which is the class of decision problems decidable by a non-deterministic Turing machine that runs in polynomial time. Equivalently, it is the class of decision problems where each "yes" instance has a polynomial size certificate, and certificates can be checked by a polynomial time deterministic Turing machine. The class of problems for which this is true for the "no" instances is called co-NP. P is trivially a subset of NP and of co-NP; most experts believe it is a proper subset, although this belief (the P ⊊ N P {\displaystyle {\mathsf {P}}\subsetneq {\mathsf {NP}}} hypothesis) remains unproven.
Global conveyor belt Other sources Thermohaline_circulation > Other sources Knauss, JA (1996). Introduction to Physical Oceanography. Prentice Hall.
Change of basis Function defined on a vector space Change_of_basis > Function defined on a vector space This allows defining these properties as properties of functions of a variable vector that are not related to any specific basis. So, a function whose domain is a vector space or a subset of it is a linear function, a polynomial function, a continuous function, a differentiable function, a smooth function, an analytic function,if the multivariate function that represents it on some basis—and thus on every basis—has the same property. This is specially useful in the theory of manifolds, as this allows extending the concepts of continuous, differentiable, smooth and analytic functions to functions that are defined on a manifold.
Performance and modelling of AC transmission Definition Performance_and_modelling_of_AC_transmission > Line parameters of AC transmission > Series resistance > Definition The electrical resistance of an object is property of a substance due to which it restricts the flow of electric current due to a potential difference in its two ends. The inverse quantity is electrical conductance, and is the ease with which an electric current passes. Electrical resistance shares some conceptual parallels with the notion of mechanical friction. The SI unit of electrical resistance is the ohm (Ω), while electrical conductance is measured in siemens (S).
Long-bolt engine Advantages Long-bolt_engine > Advantages For modern car manufacture, the long-bolt engine offers several advantages: Simpler assembly, with fewer components, fewer fasteners to tighten, and fewer intermediate assembly steps. Tensile forces are taken on the studs, not the cylinder block or crankcase. In particular, the force is a pure tension, rather than a twisting force owing to any offset between the bearing cap and cylinder wall bolt.
Birth injury Genetic mutations Birth_injury > Causes > Genetic mutations Genetic mutations can cause a wide variety of fetal malformations, ranging from relatively mild cleft lips to severe and even fatal deformities.
Silicon transistor Bipolar transistors Silicon_transistor > History > Bipolar transistors Bell announced the discovery of this new "sandwich" transistor in a press release on July 4, 1951.The first high-frequency transistor was the surface-barrier germanium transistor developed by Philco in 1953, capable of operating at frequencies up to 60 MHz. They were made by etching depressions into an n-type germanium base from both sides with jets of Indium(III) sulfate until it was a few ten-thousandths of an inch thick. Indium electroplated into the depressions formed the collector and emitter.AT&T first used transistors in telecommunications equipment in the No. 4A Toll Crossbar Switching System in 1953, for selecting trunk circuits from routing information encoded on translator cards.
Magnetic gear Second-order device Magnetic_gear > Gearing modes > Second-order device The Ferromagnetic stator allows for two alternative modes. The first uses the sum of the number of pole pairs of the two rotors as the number of ferromagnetic stator rods, which will drive the secondary rotor the opposite direction of rotation of the primary. The second mode has the number of stator pieces equal the difference between the pole pair counts of the rotors, which drives the secondary rotor the same direction as the primary. The table below shows the relationship between magnets in the rotors, the number of pairs, the number of iron stator rods, the gear ratio and the output direction for a pair of imaginary motors.
C Language B C_program > History > Early developments > B Thompson called the result B. He described B as "BCPL semantics with a lot of SMALGOL syntax". Like BCPL, B had a bootstrapping compiler to facilitate porting to new machines. However, few utilities were ultimately written in B because it was too slow, and could not take advantage of PDP-11 features such as byte addressability.
Water meters Velocity water meters Water_meters > Types of metering devices > Velocity water meters A velocity-type meter measures the velocity of flow through a meter of known internal capacity. The speed of the flow can then be converted into a volume of flow to determine the usage. There are several types of meters that measure water flow velocity, including jet meters (single-jet and multi-jet), turbine meters, propeller meters and mag meters. Most velocity-based meters have an adjustment vane for calibrating the meter to the required accuracy.
Internet Protocol version 6 Simplified processing by routers Internet_Protocol_version_6 > Comparison with IPv4 > Simplified processing by routers The packet header in IPv6 is simpler than the IPv4 header. Many rarely used fields have been moved to optional header extensions. The IPv6 packet header has simplified the process of packet forwarding by routers.
Fick's laws of diffusion Biological perspective Fick's_Law > Applications > Biological perspective D is the diffusion constant of the solute unit m2⋅s−1. t is time unit s. c2, c1 concentration should use unit mol m−3, so flux unit becomes mol s−1.The flux is decay over the square root of time because a concentration gradient builds up near the membrane over time under ideal conditions.

Subsets and Splits

No community queries yet

The top public SQL queries from the community will appear here once available.