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Human–computer information retrieval Summary Human–computer_information_retrieval Human–computer information retrieval (HCIR) is the study and engineering of information retrieval techniques that bring human intelligence into the search process. It combines the fields of human-computer interaction (HCI) and information retrieval (IR) and creates systems that improve search by taking into account the human context, or through a multi-step search process that provides the opportunity for human feedback.
Glossary of geography terms (N–Z) W Glossary_of_geography_terms_(N–Z) > W well A hole or shaft dug into the ground to access liquid resources, especially water, oil, or gas, from beneath the Earth's surface. Water wells typically tap into natural groundwater aquifers and remain filled with water up to the level of the water table, which can vary seasonally. The water is drawn up by a pump, or by using containers such as buckets that are raised mechanically or by hand.
Cardiovascular magnetic resonance imaging Uses Cardiac_magnetic_resonance > Uses Cardiovascular MRI is complementary to other imaging techniques, such as echocardiography, cardiac CT, and nuclear medicine. The technique has a key role in evidence-based diagnosis and treatment of cardiovascular disease. Its applications include assessment of myocardial ischemia and viability, cardiomyopathies, myocarditis, iron overload, vascular diseases, and congenital heart disease. It is the reference standard for the assessment of cardiac structure and function, and is valuable for diagnosis and surgical planning in complex congenital heart disease.Combined with vasodilator stress, it has a role in detecting and characterizing myocardial ischemia due to disease affecting the epicardial vessels and microvasculature.
Drug resistance Summary Resistance_to_antiviral_drugs When an organism is resistant to more than one drug, it is said to be multidrug-resistant. The development of antibiotic resistance in particular stems from the drugs targeting only specific bacterial molecules (almost always proteins). Because the drug is so specific, any mutation in these molecules will interfere with or negate its destructive effect, resulting in antibiotic resistance.
Benign intracranial hypertension Signs and symptoms Idiopathic_intracranial_hypertension > Signs and symptoms The most common symptom of IIH is severe headache, which occurs in almost all (92–94%) cases. It is characteristically worse in the morning, generalized in character and throbbing in nature. It may be associated with nausea and vomiting. The headache can be made worse by any activity that further increases the intracranial pressure, such as coughing and sneezing.
Vaccine ingredients Immunogens Vaccine_ingredients > Immunogens The HVP vaccine contains 120 micrograms of the L1 capsid proteins from four types of human papillomavirus. The pneumococcal conjugate vaccine contains 32 micrograms of pneumococcal polysaccharide conjugated with CRM197 (a diphtheria toxin).Another variant is the RNA vaccine, which contains mRNA embedded in lipid (fat) nanoparticles. The mRNA instructs body's own cell machinery to produce the proteins that stimulate the immune response. Comirnaty, the Pfizer-BioNTech COVID-19 vaccine contains thirty micrograms of BNT162b2 RNA.
Operations Management Mathematical modeling Operations_Management > Topics > Mathematical modeling There are also fields of mathematical theory which have found applications in the field of operations management such as operations research: mainly mathematical optimization problems and queue theory. Queue theory is employed in modelling queue and processing times in production systems while mathematical optimization draws heavily from multivariate calculus and linear algebra. Queue theory is based on Markov chains and stochastic processes. Computations of safety stocks are usually based on modeling demand as a normal distribution and MRP and some inventory problems can be formulated using optimal control.When analytical models are not enough, managers may resort to using simulation.
Word stress Word stress Primary_stress > Word stress Word stress, or sometimes lexical stress, is the stress placed on a given syllable in a word. The position of word stress in a word may depend on certain general rules applicable in the language or dialect in question, but in other languages, it must be learned for each word, as it is largely unpredictable. In some cases, classes of words in a language differ in their stress properties; for example, loanwords into a language with fixed stress may preserve stress placement from the source language, or the special pattern for Turkish placenames.
Storage record Summary Storage_record In computer science, a storage record is: A group of related data, words, or fields treated as a meaningful unit; for instance, a Name, Address, and Telephone Number can be a "Personal Record". A self-contained collection of information about a single object; a record is made up of a number of distinct items, called fields. In IBM mainframes, a record is a basic unit of device-to-program data transfers. Mainframe files, properly called data sets, are traditionally structured collections of records, as opposed to modern byte stream access files. Records may have a fixed length or variable length.In Unix-like systems, a number of programs (for example, awk, join, and sort) are designed to process data consisting of records (called lines) each separated by newlines, where each record may contain a number of fields separated by spaces, commas, or some other character.
Reaction (physics) 'Equal and opposite' Reaction_(physics) > Causal misinterpretation > 'Equal and opposite' They are therefore 'equal and opposite', yet they are acting on the same object, hence they are not action-reaction forces in the sense of Newton's third law. The actual action-reaction forces in the sense of Newton's third law are the weight of the book (the attraction of the Earth on the book) and the book's upward gravitational force on the earth. The book also pushes down on the table and the table pushes upwards on the book.
Mathematical economics Agent-based computational economics Mathematical_economics > Modern mathematical economics > Agent-based computational economics It has a similarity to, and overlap with, game theory as an agent-based method for modeling social interactions. Other dimensions of the approach include such standard economic subjects as competition and collaboration, market structure and industrial organization, transaction costs, welfare economics and mechanism design, information and uncertainty, and macroeconomics.The method is said to benefit from continuing improvements in modeling techniques of computer science and increased computer capabilities. Issues include those common to experimental economics in general and by comparison and to development of a common framework for empirical validation and resolving open questions in agent-based modeling. The ultimate scientific objective of the method has been described as "test theoretical findings against real-world data in ways that permit empirically supported theories to cumulate over time, with each researcher's work building appropriately on the work that has gone before".
Algorithmic Trading Systematic Trading Algorithmic_Trading > Strategies > Systematic Trading Use of computer models to define trade goals, risk controls and rules that can execute trade orders in a methodical way. Systematic trading includes both high frequency trading (HFT, sometimes called algorithmic trading) and slower types of investment such as systematic trend following. It also includes passive index tracking. Recent research by Sergio Alvarez-Teleña (PhD) has found that injecting financial insights into this strategy surpasses a generally data-driven only calibration process.
Modulus of rigidity Summary Modulus_of_rigidity In materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S or μ, is a measure of the elastic shear stiffness of a material and is defined as the ratio of shear stress to the shear strain: G = d e f τ x y γ x y = F / A Δ x / l = F l A Δ x {\displaystyle G\ {\stackrel {\mathrm {def} }{=}}\ {\frac {\tau _{xy}}{\gamma _{xy}}}={\frac {F/A}{\Delta x/l}}={\frac {Fl}{A\Delta x}}} where τ x y = F / A {\displaystyle \tau _{xy}=F/A\,} = shear stress F {\displaystyle F} is the force which acts A {\displaystyle A} is the area on which the force acts γ x y {\displaystyle \gamma _{xy}} = shear strain. In engineering := Δ x / l = tan ⁡ θ {\displaystyle :=\Delta x/l=\tan \theta } , elsewhere := θ {\displaystyle :=\theta } Δ x {\displaystyle \Delta x} is the transverse displacement l {\displaystyle l} is the initial length of the area.The derived SI unit of shear modulus is the pascal (Pa), although it is usually expressed in gigapascals (GPa) or in thousand pounds per square inch (ksi). Its dimensional form is M1L−1T−2, replacing force by mass times acceleration.
Origin of photosynthesis Concentrating carbon Origin_of_photosynthesis > Evolution of photosynthetic pathways > Concentrating carbon The C4 metabolic pathway is a valuable recent evolutionary innovation in plants, involving a complex set of adaptive changes to physiology and gene expression patterns. About 7600 species of plants use C4 carbon fixation, which represents about 3% of all terrestrial species of plants. All these 7600 species are angiosperms. C4 plants evolved carbon concentrating mechanisms.
Cooperative principle Criticism Cooperative_principle > Criticism This may explain the criticism that the Gricean maxims can easily be misinterpreted to be a guideline for etiquette, instructing speakers on how to be moral, polite conversationalists. However, the Gricean maxims, despite their wording, are only meant to describe the commonly accepted traits of successful cooperative communication. Geoffrey Leech introduced the politeness maxims: tact, generosity, approbation, modesty, agreement, and sympathy.
Timeline of virtualization development Application virtualization Timeline_of_virtualization_development > Overview of Virtualization > As an overview, there are three levels of virtualization > Application virtualization Because VMware ThinApp is implemented in user-mode without device drivers and it does not have a client that is preinstalled, applications can run directly from USB Flash or network shares without previously needing elevated security privileges. Softricity (acquired by Microsoft) operates on a similar principle using device drivers to intercept file requests in ring0 at a level closer to the operating system. Softricity installs a client in Administrator mode which can then be accessed by restricted users on the machine.
Clastic rock Composition Clastic_rock > Sedimentary clastic rocks > Siliciclastic sedimentary rocks > Composition The composition of siliciclastic sedimentary rocks includes the chemical and mineralogical components of the framework as well as the cementing material that make up these rocks. Boggs divides them into four categories; major minerals, accessory minerals, rock fragments, and chemical sediments.Major minerals can be categorized into subdivisions based on their resistance to chemical decomposition. Those that possess a great resistance to decomposition are categorized as stable, while those that do not are considered less stable.
Search tree Ternary search tree Search_tree > Types of Trees > Ternary search tree A ternary search tree is a type of tree that can have 3 nodes: a low child, an equal child, and a high child. Each node stores a single character and the tree itself is ordered the same way a binary search tree is, with the exception of a possible third node. Searching a ternary search tree involves passing in a string to test whether any path contains it. The time complexity for searching a balanced ternary search tree is O(log n).
Optical scattering Single and multiple scattering Scattering_process > Single and multiple scattering In certain rare circumstances, multiple scattering may only involve a small number of interactions such that the randomness is not completely averaged out. These systems are considered to be some of the most difficult to model accurately. The description of scattering and the distinction between single and multiple scattering are tightly related to wave–particle duality.
Matrix eigenvalue problem Algorithms Eigenvalue_algorithm > Algorithms The eigenvalue algorithm can then be applied to the restricted matrix. This process can be repeated until all eigenvalues are found. If an eigenvalue algorithm does not produce eigenvectors, a common practice is to use an inverse iteration based algorithm with μ set to a close approximation to the eigenvalue.
Viral pneumonia Pathophysiology Viral_pneumonia > Pathophysiology Further damage to the lungs occurs when the immune system responds to the infection. White blood cells, in particular lymphocytes, are responsible for activating a variety of chemicals (cytokines) which cause leaking of fluid into the alveoli. The combination of cellular destruction and fluid-filled alveoli interrupts the transportation of oxygen into the bloodstream. In addition to the effects on the lungs, many viruses affect other organs and can lead to illness affecting many different bodily functions. Some viruses also make the body more susceptible to bacterial infection; for this reason, bacterial pneumonia often complicates viral pneumonia.
Élie Cartan Differential systems Élie_Cartan > Work > Differential systems Cartan's methods in the theory of differential systems are perhaps his most profound achievement. Breaking with tradition, he sought from the start to formulate and solve the problems in a completely invariant fashion, independent of any particular choice of variables and unknown functions. He thus was able for the first time to give a precise definition of what is a "general" solution of an arbitrary differential system. His next step was to try to determine all "singular" solutions as well, by a method of "prolongation" that consists in adjoining new unknowns and new equations to the given system in such a way that any singular solution of the original system becomes a general solution of the new system.
Atomic hydrogen Visualizing the hydrogen electron orbitals Hydrogen_atom > Theoretical analysis > Visualizing the hydrogen electron orbitals The image to the right shows the first few hydrogen atom orbitals (energy eigenfunctions). These are cross-sections of the probability density that are color-coded (black represents zero density and white represents the highest density). The angular momentum (orbital) quantum number ℓ is denoted in each column, using the usual spectroscopic letter code (s means ℓ = 0, p means ℓ = 1, d means ℓ = 2). The main (principal) quantum number n (= 1, 2, 3, ...) is marked to the right of each row.
Flywheel energy storage Counterbalancing of angular momentum Flywheel_energy_storage > Physical characteristics > Effects of angular momentum in vehicles > Counterbalancing of angular momentum An alternative solution to the problem is to have two joined flywheels spinning synchronously in opposite directions. They would have a total angular momentum of zero and no gyroscopic effect. A problem with this solution is that when the difference between the momentum of each flywheel is anything other than zero the housing of the two flywheels would exhibit torque. Both wheels must be maintained at the same speed to keep the angular velocity at zero.
Whitehill Formation Lithologies Whitehill_Formation > Description > Lithologies The Whitehill Formation has been subdivided into two major subunits according to their weathering color in outcrops. The lower and thicker part consists mainly of bluish- to greenish-grey shales and mudstones, which grade upward into more light brownish, buff weathering, slightly coarser grained siltstones. This zone is conformably overlain by white weathering shales, with intermittent chert lenses and pyritic stringers; the latter rarely exceeding 20 millimetres (0.79 in) in thickness. The sedimentary structure is generally massive, however laminations do occur that resemble algal lamellae.
Gravity model of trade Theoretical justifications and research Gravity_model_of_trade > Theoretical justifications and research The home market effect showed a relationship in the gravity estimation for differentiated goods, but showed the inverse relationship for homogeneous goods. The authors show that this result matches the theoretical predictions of reciprocal dumping playing a role in homogeneous markets. Past research using the gravity model has also sought to evaluate the impact of various variables in addition to the basic gravity equation.
Psychophysical parallelism Leibniz Psychophysical_parallelism > History > Leibniz Whenever we perceive a monad to be the cause of something, other monads are created in such a way as to seem like they are affecting the others. According to Leibniz, the entire universe was created by God to be in a pre-established harmony, so nothing in the universe actually influences anything else. Considering psychophysical parallelism thusly, you could imagine the mind and body as two identical clocks. The clocks will always be in agreement because of the pre-existing harmony between them, but will never interact. And like the two clocks, no interaction or causation among the monads that compose the mind and body is necessary because they are already synchronized.
Epsilon Eridani Cataloguing Epsilon_Eridani > Observational history > Cataloguing Because every observation of each star was numbered and Epsilon Eridani was observed three times, it got three numbers: 6581, 6582 and 6583. (Today numbers from this catalogue are used with the prefix "Lalande", or "Lal".)
Cardo polymer Summary Cardo_polymer Cardo polymers are a sub group of polymers where ring structures are pendent to the polymer backbone. The backbone carbons bonded to the pendent ring structures are quaternary centers. As such, the cyclic side group lies perpendicular to the plane of the extended (all trans conformation) polymer chain. These side rings are bulky structures which sterically hinder rotation of the backbone bonds; they also disrupt chain packing and thus create greater free volume than found in conventional polymer structures.
Septic systems Description Septic_tanks > Description The entire septic system can operate by gravity alone or, where topographic considerations require, with inclusion of a lift pump. Certain septic tank designs include siphons or other devices to increase the volume and velocity of outflow to the drainage field.
Clarke orbit Retired satellites GEO_orbit > Retired satellites Geostationary satellites require some station keeping to keep their position, and once they run out of thruster fuel they are generally retired. The transponders and other onboard systems often outlive the thruster fuel and by allowing the satellite to move naturally into an inclined geosynchronous orbit some satellites can remain in use, or else be elevated to a graveyard orbit. This process is becoming increasingly regulated and satellites must have a 90% chance of moving over 200 km above the geostationary belt at end of life.
Corticotropin-releasing hormone receptor 1 Mechanism of activation Corticotropin_releasing_hormone_receptor_1 > Mechanism of activation CRF1 is activated through the binding of CRF or a CRF-agonist. The ligand binding and subsequent receptor conformational change depends on three different sites in the second and third extracellular domains of CRF1.In the majority of tissues, CRF1 is coupled to a stimulatory G-protein that activates the adenylyl cyclase signaling pathway, and ligand-binding triggers an increase in cAMP levels. However, the signal can be transmitted along multiple signal transduction cascades, according to the structure of the receptor and the region of its expression. Alternate signaling pathways activated by CRF1 include PKC and MAPK. This wide variety of cascades suggests that CRF1 mediates tissue-specific responses to CRF and CRF-agonists.
Non-carbon economy Renewable energy and energy efficiency Low-carbon_economy > Energy policy > Renewable energy and energy efficiency Scaling up renewable energy as part of a low emission development strategy can diversify a country's energy mixes and reduces dependence on imports. In the process of decarbonizing heat and transport through electrification, potential changes to electricity peak demand need to be anticipated whilst switching to alternative technologies such as heat pumps for electric vehicles.Installing local renewable capacities can also lower geopolitical risks and exposure to fuel price volatility, and improve the balance of trade for importing countries (noting that only a handful of countries export oil and gas). Renewable energy offers lower financial and economic risk for businesses through a more stable and predictable cost base for energy supply.Energy efficiency gains in recent decades have been significant, but there is still much more that can be achieved.
Tangent lines to two circles Degenerate cases Tangent_lines_to_circles > Tangent lines to two circles > Degenerate cases Two distinct circles may have between zero and four bitangent lines, depending on configuration; these can be classified in terms of the distance between the centers and the radii. If counted with multiplicity (counting a common tangent twice) there are zero, two, or four bitangent lines. Bitangent lines can also be generalized to circles with negative or zero radius. The degenerate cases and the multiplicities can also be understood in terms of limits of other configurations – e.g., a limit of two circles that almost touch, and moving one so that they touch, or a circle with small radius shrinking to a circle of zero radius.
SAW filter Summary Filter_(signal_processing) Filters may be: non-linear or linear time-variant or time-invariant, also known as shift invariance. If the filter operates in a spatial domain then the characterization is space invariance. causal or non-causal: A filter is non-causal if its present output depends on future input. Filters processing time-domain signals in real time must be causal, but not filters acting on spatial domain signals or deferred-time processing of time-domain signals. analog or digital discrete-time (sampled) or continuous-time passive or active type of continuous-time filter infinite impulse response (IIR) or finite impulse response (FIR) type of discrete-time or digital filter.
Zircon (microkernel) Kernel Fuchsia_(operating_system) > Overview > Kernel It is composed of a kernel with a small set of user services, drivers, and libraries which are all necessary for the system to boot, communicate with the hardware, and load the user processes. Its present features include handling threads, virtual memory, inter-process communication, and waiting for changes in the state of objects. It is heavily inspired by Unix kernels but differs greatly.
Metal acetylide Structure and bonding Acetylide > Structure and bonding Alkali metal and alkaline earth metal acetylides of the general formula MC≡CM are salt-like Zintl phase compounds, containing C2−2 ions. Evidence for this ionic character can be seen in the ready hydrolysis of these compounds to form acetylene and metal oxides, there is also some evidence for the solubility of C2−2 ions in liquid ammonia. The C2−2 ion has a closed shell ground state of 1Σ+g, making it isoelectronic to a neutral molecule N2, which may afford it some stability. Analogous acetylides prepared from other metals, particularly transition metals, show covalent character and are invariably associated with their metal centers.
Metaphase I Summary Meiosis_II Thus, alternating cycles of meiosis and fertilization enable sexual reproduction, with successive generations maintaining the same number of chromosomes. For example, diploid human cells contain 23 pairs of chromosomes including 1 pair of sex chromosomes (46 total), half of maternal origin and half of paternal origin. Meiosis produces haploid gametes (ova or sperm) that contain one set of 23 chromosomes.
Euler numbers As a determinant Euler_numbers > Explicit formulas > As a determinant 1 1 ( 2 n ) ! 1 ( 2 n − 2 ) ! ⋯ 1 4 !
Acquired Immunodeficiency Syndrome Economic impact HIV_transmission > Society and culture > Economic impact Before death they will not only be unable to work, but will also require significant medical care. It is estimated that as of 2007 there were 12 million AIDS orphans. Many are cared for by elderly grandparents.Returning to work after beginning treatment for HIV/AIDS is difficult, and affected people often work less than the average worker.
Max pooling Pooling layer Convolutional_layer > Building blocks > Pooling layer A very common form of max pooling is a layer with filters of size 2×2, applied with a stride of 2, which subsamples every depth slice in the input by 2 along both width and height, discarding 75% of the activations: In this case, every max operation is over 4 numbers. The depth dimension remains unchanged (this is true for other forms of pooling as well). In addition to max pooling, pooling units can use other functions, such as average pooling or ℓ2-norm pooling. Average pooling was often used historically but has recently fallen out of favor compared to max pooling, which generally performs better in practice.Due to the effects of fast spatial reduction of the size of the representation, there is a recent trend towards using smaller filters or discarding pooling layers altogether. "Region of Interest" pooling (also known as RoI pooling) is a variant of max pooling, in which output size is fixed and input rectangle is a parameter.Pooling is a downsampling method and an important component of convolutional neural networks for object detection based on the Fast R-CNN architecture.
Quantum fluctuations Summary Vacuum_fluctuations This means that pairs of virtual particles with energy Δ E {\displaystyle \Delta E} and lifetime shorter than Δ t {\displaystyle \Delta t} are continually created and annihilated in empty space. Although the particles are not directly detectable, the cumulative effects of these particles are measurable.
Quantum Machine Learning Skepticism Quantum_Machine_Learning > Skepticism “When mixing machine learning with ‘quantum,’ you catalyse a hype-condensate.” - Jacob Biamonte a contributor to the theory of quantum computation. "There is a lot more work that needs to be done before claiming quantum machine learning will actually work," - computer scientist Iordanis Kerenidis, the head of quantum algorithms at the Silicon Valley-based quantum computing startup QC Ware. "I have not seen a single piece of evidence that there exists a meaningful task for which it would make sense to use a quantum computer and not a classical computer," - physicist Ryan Sweke of the Free University of Berlin in Germany. “Don't fall for the hype!” - Frank Zickert, who is the author of probably the most practical book related to the subject beware that ”quantum computers are far away from advancing machine learning for their representation ability”, and even speaking about evaluation and optimization for any kind of useful task quantum supremacy is not yet achieved. Furthermore, nobody among the active researchers in the field make any forecasts about when it could possibly become practical.
Niche cell Summary Niche_cell Stem-cell niche refers to a microenvironment, within the specific anatomic location where stem cells are found, which interacts with stem cells to regulate cell fate. The word 'niche' can be in reference to the in vivo or in vitro stem-cell microenvironment. During embryonic development, various niche factors act on embryonic stem cells to alter gene expression, and induce their proliferation or differentiation for the development of the fetus. Within the human body, stem-cell niches maintain adult stem cells in a quiescent state, but after tissue injury, the surrounding micro-environment actively signals to stem cells to promote either self-renewal or differentiation to form new tissues.
Bacterial fermentation Definitions and etymology Anaerobic_fermentation > Definitions and etymology Below are some definitions of fermentation ranging from informal, general usages to more scientific definitions. Preservation methods for food via microorganisms (general use). Any large-scale microbial process occurring with or without air (common definition used in industry, also known as industrial fermentation). Any process that produces alcoholic beverages or acidic dairy products (general use).
Backstepping control Summary Backstepping_control In control theory, backstepping is a technique developed circa 1990 by Petar V. Kokotovic and others for designing stabilizing controls for a special class of nonlinear dynamical systems. These systems are built from subsystems that radiate out from an irreducible subsystem that can be stabilized using some other method. Because of this recursive structure, the designer can start the design process at the known-stable system and "back out" new controllers that progressively stabilize each outer subsystem. The process terminates when the final external control is reached. Hence, this process is known as backstepping.
P6m symmetry Group cm (×) Wallpaper_groups > The seventeen groups > Group cm (×) Orbifold signature: *× Coxeter notation: or Lattice: rhombic Point group: D1 The group cm contains no rotations. It has reflection axes, all parallel. There is at least one glide reflection whose axis is not a reflection axis; it is halfway between two adjacent parallel reflection axes. This group applies for symmetrically staggered rows (i.e. there is a shift per row of half the translation distance inside the rows) of identical objects, which have a symmetry axis perpendicular to the rows. Examples of group cm
UCSC Genome Browser Browser functionality UCSC_Genome_Browser > Browser functionality By pre-aligning millions of RNA secuences from GenBank to each of the 244 genome assemblies (many of the 108 species have more than one assembly), the browser allows instant access to the alignments of any RNA to any of the hosted species. The juxtaposition of the many types of data allow researchers to display exactly the combination of data that will answer specific questions. A pdf/postscript output functionality allows export of a camera-ready image for publication in academic journals.
Sleep mode Summary Sleep_mode Sleep mode (or suspend to RAM) is a low power mode for electronic devices such as computers, televisions, and remote controlled devices. These modes save significantly on electrical consumption compared to leaving a device fully on and, upon resume, allow the user to avoid having to reissue instructions or to wait for a machine to boot. Many devices signify this power mode with a pulsed or red colored LED power light.
Solar backpack Summary Solar_backpack Examples of solar chargers in popular use include: Small portable models designed to charge a range of different mobile phones, cell phones, iPods or other portable audio equipment. Fold out models designed to sit on the dashboard of an automobile and plug into the cigar/12v lighter socket to keep the battery topped up while the vehicle is not in use. Flashlights/torches, often combined with a secondary means of charging, such as a kinetic (hand crank generator) charging system. Public solar chargers permanently installed in public places, such as parks, squares and streets, which anyone can use for free.
Online fair division The costly reallocation problem Online_fair_division > Online arrival of resources > The costly reallocation problem In some cases, items that were previously allocated may be reallocated, but reallocation is costly, so the number of adjustments should be as small as possible. An example is the allocation of expensive scientific equipment among different university departments. Each piece of equipment is allocated as soon as it arrives, but some previously allocated equipment may be reallocated in order to attain a fairer overall allocation. He, Procaccia and Psomas show that, with two agents, algorithms that are informed about values of future items can attain EF1 without any adjustments, whereas uninformed algorithms require Θ(T) adjustments. With three or more agents, even informed algorithms must use Ω(T) adjustments, and there is an uninformed algorithm that attains EF1 with O(T3/2) adjustments.
Protected memory Simulated segmentation Protected_memory > Methods > Simulated segmentation Simulation is the use of a monitoring program to interpret the machine code instructions of some computer architectures. Such an instruction set simulator can provide memory protection by using a segmentation-like scheme and validating the target address and length of each instruction in real time before actually executing them. The simulator must calculate the target address and length and compare this against a list of valid address ranges that it holds concerning the thread's environment, such as any dynamic memory blocks acquired since the thread's inception, plus any valid shared static memory slots. The meaning of "valid" may change throughout the thread's life depending upon context. It may sometimes be allowed to alter a static block of storage, and sometimes not, depending upon the current mode of execution, which may or may not depend on a storage key or supervisor state.It is generally not advisable to use this method of memory protection where adequate facilities exist on a CPU, as this takes valuable processing power from the computer. However, it is generally used for debugging and testing purposes to provide an extra fine level of granularity to otherwise generic storage violations and can indicate precisely which instruction is attempting to overwrite the particular section of storage which may have the same storage key as unprotected storage.
Numerical optimisation Major subfields Numerical_optimization > Major subfields Usually, heuristics do not guarantee that any optimal solution need be found. On the other hand, heuristics are used to find approximate solutions for many complicated optimization problems. Constraint satisfaction studies the case in which the objective function f is constant (this is used in artificial intelligence, particularly in automated reasoning).
Jazz music Modal jazz Jazz_music > Post-war jazz > Modal jazz Modal jazz is a development which began in the later 1950s which takes the mode, or musical scale, as the basis of musical structure and improvisation. Previously, a solo was meant to fit into a given chord progression, but with modal jazz, the soloist creates a melody using one (or a small number of) modes. The emphasis is thus shifted from harmony to melody: "Historically, this caused a seismic shift among jazz musicians, away from thinking vertically (the chord), and towards a more horizontal approach (the scale)", explained pianist Mark Levine. The modal theory stems from a work by George Russell.
Supramolecular catalysis Transition state analogue selection/screening approach Supramolecular_catalysis > Approaches to making supramolecular catalysts > Transition state analogue selection/screening approach Assuming that catalytic activity largely depends on the catalyst's affinity to the transition state, one could synthesize a transition state analog (TSA), a structure that resembles the transition state of the reaction. Then one could link the TSA to a solid-support or identifiable tag and use that TSA to select an optimal catalyst from a mixture of many different potential catalysts generated chemically or biologically by a diversity oriented synthesis. This method allows quick screening of a library of diverse compounds. It does not require as much synthetic effort and it allows a study of various catalytic factors simultaneously. Hence the method could potentially yield an efficient catalyst that we could not have designed with our current knowledge.Many catalytic antibodies were developed and studied using this approach.
Role-playing Simulation Role-playing > Training > Simulation One of the first uses of computers was to simulate real-world conditions for participants role-playing the flying of aircraft. Flight simulators used computers to solve the equations of flight and train future pilots. The army began full-time role-playing simulations with soldiers using computers both within full scale training exercises and for training in numerous specific tasks under wartime conditions. Examples include weapon firing, vehicle simulators, and control station mock-ups.
Object-oriented database Standards Object_persistence > Standards By 2001, most of the major object database and object–relational mapping vendors claimed conformance to the ODMG Java Language Binding. Compliance to the other components of the specification was mixed. In 2001, the ODMG Java Language Binding was submitted to the Java Community Process as a basis for the Java Data Objects specification.
Wei-Ming Ni Major publications Wei-Ming_Ni > Major publications Diffusion, cross-diffusion, and their spike-layer steady states. Notices Amer. Math. Soc. 45 (1998), no. 1, 9–18.
Health outcomes for adults born prematurely Endocrine/metabolic Health_outcomes_for_adults_born_prematurely > Endocrine/metabolic Risks type 1 diabetes and type 2 diabetes lipid disorders cardiometabolic disordersThyroid dysfunction is common in preterm infants. Independently from birth weight, preterms have higher rates of hypothalamus-pituitary-thyroid axis dysfunction later in life.
Gauss's theorem Continuity equations Gauss'_theorem > Applications > Differential and integral forms of physical laws > Continuity equations Continuity equations offer more examples of laws with both differential and integral forms, related to each other by the divergence theorem. In fluid dynamics, electromagnetism, quantum mechanics, relativity theory, and a number of other fields, there are continuity equations that describe the conservation of mass, momentum, energy, probability, or other quantities. Generically, these equations state that the divergence of the flow of the conserved quantity is equal to the distribution of sources or sinks of that quantity. The divergence theorem states that any such continuity equation can be written in a differential form (in terms of a divergence) and an integral form (in terms of a flux).
Unscented transform Background Unscented_transform > Background When the covariance is not zero the transformed mean will not generally be equal to f ( x , y ) {\displaystyle f(x,y)} and it is not even possible to determine the mean of the transformed probability distribution from only its prior mean and covariance. Given this indeterminacy, the nonlinearly transformed mean and covariance can only be approximated. The earliest approximation was to linearize the nonlinear function and apply the resulting Jacobian matrix to the given mean and covariance. This is the basis of the extended Kalman Filter (EKF), and although it was known to yield poor results in many circumstances, there was no practical alternative for many decades.
Linked list Sentinel nodes Linked_lists > Basic concepts and nomenclature > Sentinel nodes In some implementations an extra 'sentinel' or 'dummy' node may be added before the first data record or after the last one. This convention simplifies and accelerates some list-handling algorithms, by ensuring that all links can be safely dereferenced and that every list (even one that contains no data elements) always has a "first" and "last" node.
Additive disequilibrium and z statistic Summary Additive_disequilibrium_and_z_statistic To do this, divide D ^ {\displaystyle {\widehat {D}}} by its standard deviation, which gives the simplified equation: z = D ^ n p ^ 1 ( 1 − p ^ 1 ) {\displaystyle z={\frac {{\widehat {D}}{\sqrt {n}}}{{\widehat {p}}_{1}(1-{\widehat {p}}_{1})}}} When z is large, D ^ {\displaystyle {\widehat {D}}} and thus the departure from Hardy Weinberg Equilibrium are also large. If the value of z is sufficiently large, it is unlikely that the deviations would occur by chance and thus the hypothesis of Hardy Weinberg Equilibrium can be rejected.To determine if z is significantly larger or smaller than expected under Hardy Weinberg Equilibrium, find "the probability of observing" a value as or more extreme as the observed z "under the null hypothesis". The tail probability is normally used, P {\displaystyle \mathbb {P} } (y > z), where y is standard normal random variable.
Oracle Spatial and Graph RDF semantic Oracle_Spatial_and_Graph > Components > RDF semantic The RDF Semantic Graph feature supports the World Wide Web Consortium (W3C) RDF standards. It provides RDF data management, querying and inferencing that are commonly used in a variety of applications ranging from semantic data integration to social network analysis and linked open data applications. Its features include: An RDF triple store and ontology management with automatic partitioning and data compression. Proven scalability to over 54 billion triples (LUBM 200K benchmark) with scalability to the 8 petabyte limit of Oracle Database.
Arginine decarboxylase Function Arginine_decarboxylase > Function Arginine decarboxylase is one of the main components of arginine-dependent acid resistance (AR3) that allows E. coli to survive long enough in the highly acidic environment of the stomach to pass through the digestive tract and infect a human host. The enzyme consumes a cytoplasmic proton in the decarboxylation reaction, preventing the pH of the cell from becoming too acidic. The activity of the enzyme is dependent upon the surrounding pH. At more basic cellular pH levels, the enzyme exists in an inactive homodimer form, as electrostatic repulsion between negatively-charged acidic residues in the wing domains prevent homodimers from assembling into the catalytically active decamer.
Spectroscopic redshift Observations in astronomy Redshift > Observations in astronomy The redshift observed in astronomy can be measured because the emission and absorption spectra for atoms are distinctive and well known, calibrated from spectroscopic experiments in laboratories on Earth. When the redshift of various absorption and emission lines from a single astronomical object is measured, z is found to be remarkably constant. Although distant objects may be slightly blurred and lines broadened, it is by no more than can be explained by thermal or mechanical motion of the source. For these reasons and others, the consensus among astronomers is that the redshifts they observe are due to some combination of the three established forms of Doppler-like redshifts.
Atheronals Effects of atheronals in human body Atheronals > Effects of atheronals in human body Furthermore, such cholesterol oxidation items have been found in the brains of autopsy specimens from Alzheimer’s disease patients. The ozonolyzed cholesterol quickens amyloidogenesis in these patients. They may play a crucial job in the pathogenesis of atherosclerosis and neurodegenerative infections. == References ==
Anticipatory anxiety Anxiety disorders Anticipatory_anxiety > Causes > Anxiety disorders Anticipatory anxiety is a feature of social anxiety disorder. The Social Phobia Scale, a general self-report questionnaire used as measure for social anxiety disorder, contains the 'anticipatory anxiety related to being observed' as one of its main diagnostic items. Peer victimisation, such as bullying, may increase levels of anticipatory anxiety and of developing social anxiety disorder.Avoidance behaviour associated with post-traumatic stress disorder increases anticipatory anxiety. This can be an indicator of post-traumatic anxiety disorders such as agoraphobia, social anxiety disorder, obsessive-compulsive disorder, or separation anxiety.
Reptation Monte Carlo Summary Reptation_Monte_Carlo When you propagate the Schrödinger equation in time, you get the dynamics of the system under study. When you propagate it in imaginary time, you get a system that tends towards the ground state of the system. When substituting i t {\displaystyle it} in place of t {\displaystyle t} , the Schrodinger equation becomes identical with a diffusion equation.
Empirical statistical laws Examples Empirical_statistical_laws > Examples According to the "law", given some dataset of text, the frequency of a word is inversely proportional to its frequency rank. In other words, the second most common word should appear about half as often as the most common word, and the fifth most common world would appear about once every five times the most common word appears.
Labyrinth problem Recursive algorithm Wall_follower > Recursive algorithm If given an omniscient view of the maze, a simple recursive algorithm can tell one how to get to the end. The algorithm will be given a starting X and Y value. If the X and Y values are not on a wall, the method will call itself with all adjacent X and Y values, making sure that it did not already use those X and Y values before. If the X and Y values are those of the end location, it will save all the previous instances of the method as the correct path.
Map symbol Visual variables Map_symbol > Visual variables The most common set of visual variables, as canonized in cartography textbooks and the Geographic Information Science and Technology Body of Knowledge, includes the following: Size, how much space a symbol occupies on a map, most commonly refers to the area of point symbols, and the thickness of line symbols, although the cartogram controls the size of area features proportional to a given variable. Size has been shown to be very effective at conveying quantitative data, and in the visual hierarchy. Shape is most commonly discussed in the context of point symbols (as the shapes of lines and areas are typically fixed by geographic reality), and is generally only used to differentiate nominal categories.
Imitation game Interpretations Turing_Test > Interpretations With the same object therefore it is possible that one man would consider it as intelligent and another would not; the second man would have found out the rules of its behaviour.Following this remark and similar ones scattered throughout Turing's publications, Diane Proudfoot claims that Turing held a response-dependence approach to intelligence, according to which an intelligent (or thinking) entity is one that appears intelligent to an average interrogator. Bernardo Gonçalves claims that Turing intended his test to be a thought experiment, one which would supposedly cause humans to realize that machines should be considered as intelligent entities. Taking up both lines, Shlomo Danziger promotes a socio-technological interpretation, according to which Turing saw the imitation game not as an intelligence test but as a technological aspiration - one whose realization would likely involve a change in society's attitude toward machines.
S-Nitroso-N-acetylpenicillamine Summary S-Nitroso-N-acetylpenicillamine S-Nitroso-N-acetylpenicillamine (SNAP) is the organosulfur compound with the formula ONSC(CH3)2CH(NHAc)CO2H. It is a green solid.SNAP is an S-nitrosothiol and is used as a model for the general class of S-nitrosothiols which have received much attention in biochemistry because nitric oxide and some organic nitroso derivatives serve as signaling molecules in living systems, especially related to vasodilation. SNAP is derived from the amino acid penicillamine. S-Nitrosoglutathione is a related agent. == References ==
Approximate Bayesian Computation Indispensable quality controls Approximate_Bayesian_Computation > Pitfalls and remedies > Indispensable quality controls The resulting discrepancy distributions have been used for selecting models that are in agreement with many aspects of the data simultaneously, and model inconsistency is detected from conflicting and co-dependent summaries. Another quality-control-based method for model selection employs ABC to approximate the effective number of model parameters and the deviance of the posterior predictive distributions of summaries and parameters. The deviance information criterion is then used as measure of model fit.
Chemical energetics System constraints Chemical_energetics > Non-equilibrium > System constraints The extent variable for the reaction can increase only if the piston moves out, and conversely if the piston is pushed inward, the reaction is driven backwards. Similarly, a redox reaction might occur in an electrochemical cell with the passage of current through a wire connecting the electrodes. The half-cell reactions at the electrodes are constrained if no current is allowed to flow.
Flash flood emergency Warning Flash_flood_warning > Example of a flash flood warning and emergency > Warning HAZARD...Flash flooding caused by thunderstorms. SOURCE...Doppler radar. IMPACT...Flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other drainage and low lying areas.
Automatic variable Java Automatic_variable > In specific programming languages > Java (Called local variables.) Similar to C and C++, but there is no auto or register keyword. However, the Java compiler will not allow the usage of a not-explicitly-initialized local variable and will give a compilation error (unlike C and C++ where the compiler will usually only give a warning). The Java standard demands that every local variable must be explicitly initialized before being used. This differs from instance variables, which are implicitly initialized with default values (which are 0 for numbers and null for objects).
Proto-value function Motivation Proto-value_function > Motivation Value function approximation is a critical component to solving Markov decision processes (MDPs) defined over a continuous state space. A good function approximator allows a reinforcement learning (RL) agent to accurately represent the value of any state it has experienced, without explicitly storing its value. Linear function approximation using basis functions is a common way of constructing a value function approximation, like radial basis functions, polynomial state encodings, and CMACs. However, parameters associated with these basis functions often require significant domain-specific hand-engineering. Proto-value functions attempts to solve this required hand-engineering by accounting for the underlying manifold structure of the problem domain.
Actor network theory ANT in arts Actor_network_theory > ANT in practice > ANT in arts ANT is a big influencer in the development of design. In the past, researchers or scholars from design field mainly view the world as a human interactive situation. No matter what design we applied, it is for human's action.
Thraustochytrids Ultrastructure Thraustochytrids > Morphology > Ultrastructure Within the granular cytoplasm lies single dictyosomes, centrioles, endoplasmic reticulum, mitochondria, and lipid bodies in some cases. Thraustochytrids contain many mitochondria, which are polymorphic and have tubular cristae. Made of sulphated polysaccharides, the cell wall of thraustochytrids are multilamellate and non-cellulosic. The cell wall is derived from the dictyosome cisternae during thallus development, where circular scales (vesicles) form on the basal membrane to merge.
History of mathematical notation Early 20th-century notation History_of_mathematical_notation > Symbolic stage > Contemporary notation and topics > Early 20th-century notation It can also be used to denote abstract vectors and linear functionals. It is so called because the inner product (or dot product on a complex vector space) of two states is denoted by a ⟨bra\|ket⟩ consisting of a left part, ⟨φ\|, and a right part, \|ψ⟩. The notation was introduced in 1939 by Paul Dirac, though the notation has precursors in Grassmann's use of the notation for his inner products nearly 100 years previously.Bra–ket notation is widespread in quantum mechanics: almost every phenomenon that is explained using quantum mechanics—including a large portion of modern physics—is usually explained with the help of bra–ket notation.
Instruction pipeline Pipeline bubble Pipelined_processor > Illustrated example > Pipeline bubble A pipelined processor may deal with hazards by stalling and creating a bubble in the pipeline, resulting in one or more cycles in which nothing useful happens. In the illustration at right, in cycle 3, the processor cannot decode the purple instruction, perhaps because the processor determines that decoding depends on results produced by the execution of the green instruction. The green instruction can proceed to the Execute stage and then to the Write-back stage as scheduled, but the purple instruction is stalled for one cycle at the Fetch stage. The blue instruction, which was due to be fetched during cycle 3, is stalled for one cycle, as is the red instruction after it.
IP Pascal Constant expressions IP_Pascal > Language > Constant expressions A constant declaration can contain expressions of other constants const b = a+10;
Douglas Hartree Later life and work Douglas_Hartree > Later life and work For this he selected a problem involving the flow of a compressible fluid over a surface, such as air over the surface of a wing travelling faster than the speed of sound.At the end of 1945 or very early in 1946 Hartree briefed Maurice Wilkes of the University of Cambridge on the comparative developments in computing in the USA which he had seen. Wilkes, then received an invitation from the Moore School of Electrical Engineering (the builders of ENIAC) to attend a course on electronic computers. Before leaving for this, Hartree was able to brief him more fully on ENIAC.
Mechanical system Mechanisms Mechanical_device > Mechanisms The assemblies that control movement are also called "mechanisms." Mechanisms are generally classified as gears and gear trains, which includes belt drives and chain drives, cam and follower mechanisms, and linkages, though there are other special mechanisms such as clamping linkages, indexing mechanisms, escapements and friction devices such as brakes and clutches. The number of degrees of freedom of a mechanism, or its mobility, depends on the number of links and joints and the types of joints used to construct the mechanism. The general mobility of a mechanism is the difference between the unconstrained freedom of the links and the number of constraints imposed by the joints. It is described by the Chebychev-Grübler-Kutzbach criterion.
Process planning Future development Process_planning > Future development The system created is highly specific, the concepts can be extrapolated to other enterprises. Traditional CAPP methods that optimize plans in a linear manner have not been able to satisfy the need for flexible planning, so new dynamic systems will explore all possible combinations of production processes, and then generate plans according to available machining resources. For example, K.S. Lee et al. states that "By considering the multi-selection tasks simultaneously, a specially designed genetic algorithm searches through the entire solution space to identify the optimal plan".
ZFS Data integrity ZFS > Features > Data integrity One major feature that distinguishes ZFS from other file systems is that it is designed with a focus on data integrity by protecting the user's data on disk against silent data corruption caused by data degradation, power surges (voltage spikes), bugs in disk firmware, phantom writes (the previous write did not make it to disk), misdirected reads/writes (the disk accesses the wrong block), DMA parity errors between the array and server memory or from the driver (since the checksum validates data inside the array), driver errors (data winds up in the wrong buffer inside the kernel), accidental overwrites (such as swapping to a live file system), etc. A 1999 study showed that neither any of the then-major and widespread filesystems (such as UFS, Ext, XFS, JFS, or NTFS), nor hardware RAID (which has some issues with data integrity) provided sufficient protection against data corruption problems. Initial research indicates that ZFS protects data better than earlier efforts. It is also faster than UFS and can be seen as its replacement.
Superparamagnetic limit Biomedical applications Superparamagnetism > Applications > Biomedical applications Imaging: contrast agents in magnetic resonance imaging (MRI) Magnetic separation: cell-, DNA-, protein- separation, RNA fishing Treatments: targeted drug delivery, magnetic hyperthermia, magnetofection
Eigenvalue, eigenvector, and eigenspace Eigenspaces, geometric multiplicity, and the eigenbasis for matrices Spectral_properties > Eigenvalues and eigenvectors of matrices > Eigenspaces, geometric multiplicity, and the eigenbasis for matrices Similarly, because E is a linear subspace, it is closed under scalar multiplication. That is, if v ∈ E and α is a complex number, (αv) ∈ E or equivalently A(αv) = λ(αv). This can be checked by noting that multiplication of complex matrices by complex numbers is commutative.
RpoS Translational control of rpoS RpoS > Environmental signal to activation: regulation of RpoS > Translational control of rpoS However, the RNA-binding protein Hfq is implicated in the process. Hfq binds to rpoS mRNA in vitro and may thereby modify rpoS mRNA structure for optimal translation. Hfq activates both DsrA and RprA.
Illustrative model of greenhouse effect on climate change Structure of the atmosphere Illustrative_model_of_greenhouse_effect_on_climate_change > Structure of the atmosphere The troposphere and tropopause together consist of ~99% of the atmospheric CO2. Inside the troposphere, the CO2 drops with altitude approximately exponentially, with a typical length of 6.3 km; this means that the density at height y is approximately proportional to exp(-y/6.3 km), and it goes down to 37% at 6.3 km, and to 17% at 11 km. Higher through the tropopause, density continues dropping exponentially, albeit faster, with a typical length of 4.2 km.
Anaphase I Molecular regulation Anaphase_I > Molecular regulation How a cell proceeds to meiotic division in meiotic cell division is not well known. Maturation promoting factor (MPF) seemingly have role in frog Oocyte meiosis. In the fungus S. pombe. there is a role of MeiRNA binding protein for entry to meiotic cell division.It has been suggested that Yeast CEP1 gene product, that binds centromeric region CDE1, may play a role in chromosome pairing during meiosis-I.Meiotic recombination is mediated through double stranded break, which is catalyzed by Spo11 protein.
Glossary of experimental design Glossary Glossary_of_experimental_design > Glossary Note: The importance of randomization cannot be over stressed. Randomization is necessary for conclusions drawn from the experiment to be correct, unambiguous and defensible. Regression discontinuity design: A design in which assignment to a treatment is determined at least partly by the value of an observed covariate lying on either side of a fixed threshold.
Professional ethic Separatism Professional_ethics > Examples > Separatism This would be a disrespect of the patient's autonomy, as it denies the patient information that could have a great impact on his or her life. This would generally be seen as morally wrong. However, if the end of improving and maintaining health is given a moral priority in society, then it may be justifiable to contravene other moral demands in order to meet this goal.
Linked list Using sentinel nodes Linked_list > Tradeoffs > Using sentinel nodes The list handle should then be a pointer to the last data node, before the sentinel, if the list is not empty; or to the sentinel itself, if the list is empty. The same trick can be used to simplify the handling of a doubly linked linear list, by turning it into a circular doubly linked list with a single sentinel node. However, in this case, the handle should be a single pointer to the dummy node itself.
Named data networking Overview Named_data_networking > Overview More specifically, NDN changes the semantics of network service from delivering the packet to a given destination address to fetching data identified by a given name. The name in an NDN packet can name anything – an endpoint, a data chunk in a movie or a book, a command to turn on some lights, etc. The hope is that this conceptually simple change allows NDN networks to apply almost all of the Internet's well-tested engineering properties to a broader range of problems beyond end-to-end communications. Examples of NDN applying lessons learned from 30 years of networking engineering are that self-regulation of network traffic (via flow balance between Interest (data request) and Data packets) and security primitives (via signatures on all named data) are integrated into the protocol from the start.
Clobbering Summary Clobbering In software engineering and computer science, clobbering a file, processor register or a region of computer memory is the process of overwriting its contents completely, whether intentionally or unintentionally, or to indicate that such an action will likely occur. The Jargon File defines clobbering as To overwrite, usually unintentionally: "I walked off the end of the array and clobbered the stack." Compare mung, scribble, trash, and smash the stack.
Unsaturated hydrocarbon NMR Spectroscopy Unsaturated_hydrocarbon > Physical properties > Spectroscopic Properties > NMR Spectroscopy Since the π bondings will make cis/trans isomers, the unsaturated hydrocarbon isomers will appear differently due to different J-coupling effect. Cis vicinal hydrogens will have coupling constants in the range of 6–14 Hz, whereas the trans will have coupling constants of 11–18 Hz.In 13C NMR spectroscopy, compared to the saturated hydrocarbons, the double and triple bonds also deshiled the carbons, making them have low field shift. C=C double bonds usually have chemical shift of about 100–170 ppm.
Average mutual information Relation to conditional and joint entropy Mutual_Information > Properties > Relation to conditional and joint entropy Intuitively, if entropy H ( Y ) {\displaystyle \mathrm {H} (Y)} is regarded as a measure of uncertainty about a random variable, then H ( Y ∣ X ) {\displaystyle \mathrm {H} (Y\mid X)} is a measure of what X {\displaystyle X} does not say about Y {\displaystyle Y} . This is "the amount of uncertainty remaining about Y {\displaystyle Y} after X {\displaystyle X} is known", and thus the right side of the second of these equalities can be read as "the amount of uncertainty in Y {\displaystyle Y} , minus the amount of uncertainty in Y {\displaystyle Y} which remains after X {\displaystyle X} is known", which is equivalent to "the amount of uncertainty in Y {\displaystyle Y} which is removed by knowing X {\displaystyle X} ". This corroborates the intuitive meaning of mutual information as the amount of information (that is, reduction in uncertainty) that knowing either variable provides about the other. Note that in the discrete case H ( Y ∣ Y ) = 0 {\displaystyle \mathrm {H} (Y\mid Y)=0} and therefore H ( Y ) = I ⁡ ( Y ; Y ) {\displaystyle \mathrm {H} (Y)=\operatorname {I} (Y;Y)} . Thus I ⁡ ( Y ; Y ) ≥ I ⁡ ( X ; Y ) {\displaystyle \operatorname {I} (Y;Y)\geq \operatorname {I} (X;Y)} , and one can formulate the basic principle that a variable contains at least as much information about itself as any other variable can provide.

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