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Frequency synthesizer Principle of PLL synthesizers Frequency_synthesiser > Principle of PLL synthesizers See main article: Phase-locked loopA phase locked loop is a feedback control system. It compares the phases of two input signals and produces an error signal that is proportional to the difference between their phases. The error signal is then low pass filtered and used to drive a voltage-controlled oscillator (VCO) which creates an output frequency. The output frequency is fed through a frequency divider back to the input of the system, producing a negative feedback loop.
Atomic oxygen Singlet oxygen Oxygen_molecule > Dioxygen > Singlet oxygen Singlet oxygen is the common name used for the two metastable states of molecular oxygen (O2) with higher energy than the ground state triplet oxygen. Because of the differences in their electron shells, singlet oxygen has different chemical and physical properties than triplet oxygen, including absorbing and emitting light at different wavelengths. It can be generated in a photosensitized process by energy transfer from dye molecules such as rose bengal, methylene blue or porphyrins, or by chemical processes such as spontaneous decomposition of hydrogen trioxide in water or the reaction of hydrogen peroxide with hypochlorite.
Interpreted programming language Compilers versus interpreters Interpreted_programming_language > Compilers versus interpreters On the other hand, compiled and linked programs for small embedded systems are typically statically allocated, often hard coded in a NOR flash memory, as there is often no secondary storage and no operating system in this sense. Historically, most interpreter systems have had a self-contained editor built in. This is becoming more common also for compilers (then often called an IDE), although some programmers prefer to use an editor of their choice and run the compiler, linker and other tools manually. Historically, compilers predate interpreters because hardware at that time could not support both the interpreter and interpreted code and the typical batch environment of the time limited the advantages of interpretation.
Tolman's rule Summary Tolman's_rule Tolman's rule states that, in a certain chemical reaction, the steps involve exclusively intermediates of 18- and 16 electron configuration. The rule is an extension of the 18-electron rule. This rule was proposed by American chemist Chadwick A. Tolman. As stated above, Tolman's rule, even for reactions that proceed via 2e− steps, is incorrect because many reactions involve configurations of fewer than 16 e−.
Collective investment scheme Switzerland Managed_fund > European collective investments > Switzerland open-ended Anlagefonds (unincorporated investment fund or common fund) SICAV (Société d'investissement à capital variable) (Investment company with variable capital) closed-ended Kommanditgesellschaft für Kapitalanlagen (Limited Partnership) Société d'investissement à capital fixe\|SICAF (Société d'investissement à capital fixe) (Investment company with fixed capital)
Bacterial sepsis Pathophysiology Blood_poisoning > Pathophysiology Sepsis is caused by a combination of factors related to the particular invading pathogen(s) and to the status of the immune system of the host. The early phase of sepsis characterized by excessive inflammation (sometimes resulting in a cytokine storm) may be followed by a prolonged period of decreased functioning of the immune system. Either of these phases may prove fatal. On the other hand, systemic inflammatory response syndrome (SIRS) occurs in people without the presence of infection, for example, in those with burns, polytrauma, or the initial state in pancreatitis and chemical pneumonitis. However, sepsis also causes similar response to SIRS.
Agent-based social simulation Further studies Agent-based_social_simulation > Further studies p. 208. ISBN 0-262-55025-3.
Transgenerational epigenetics Epigenetic categories Transgenerational_epigenetic_inheritance > Epigenetic categories The prions use themselves as a template and then edit the folding of normal proteins to match their own folding pattern. The changes in the protein folding results in an alteration in the normal protein's function. This transmission of programming can also alter the chromatin and histone of the DNA and can be passed through the cytosol from parent to offspring during meiosis.
Inertial Navigation Strapdown systems Inertial_reference_system > Basic schemes > Strapdown systems The higher rate is needed to let the navigation system integrate the angular rate into an attitude accurately. The data updating algorithms (direction cosines or quaternions) involved are too complex to be accurately performed except by digital electronics. However, digital computers are now so inexpensive and fast that rate gyro systems can now be practically used and mass-produced.
Recall and precision Imbalanced data Precision_and_recall > Imbalanced data For example, for a search engine that returns 30 results (retrieved documents) out of 1,000,000 documents, the PPCR is 0.003%. According to Saito and Rehmsmeier, precision-recall plots are more informative than ROC plots when evaluating binary classifiers on imbalanced data. In such scenarios, ROC plots may be visually deceptive with respect to conclusions about the reliability of classification performance.Different from the above approaches, if an imbalance scaling is applied directly by weighting the confusion matrix elements, the standard metrics definitions still apply even in the case of imbalanced datasets. The weighting procedure relates the confusion matrix elements to the support set of each considered class.
Attention schema theory Summary of the theory Attention_schema_theory > Summary of the theory In the theory, the attention schema provides the requisite information that allows the machine to make claims about consciousness. When the machine claims to be conscious of thing X – when it claims that it has a subjective awareness, or a mental possession, of thing X – the machine is using higher cognition to access an attention schema, and reporting the information therein. For example, suppose a person looks at an apple.
Partial sums Summary Series_(mathematics) This value is the limit as n tends to infinity (if the limit exists) of the finite sums of the n first terms of the series, which are called the nth partial sums of the series. That is, When this limit exists, one says that the series is convergent or summable, or that the sequence ( a 1 , a 2 , a 3 , … ) {\displaystyle (a_{1},a_{2},a_{3},\ldots )} is summable. In this case, the limit is called the sum of the series.
Sliding mode control Summary Sliding_mode_control In control systems, sliding mode control (SMC) is a nonlinear control method that alters the dynamics of a nonlinear system by applying a discontinuous control signal (or more rigorously, a set-valued control signal) that forces the system to "slide" along a cross-section of the system's normal behavior. The state-feedback control law is not a continuous function of time. Instead, it can switch from one continuous structure to another based on the current position in the state space.
Split attention effect A visual example of split attention Split_attention_effect > A visual example of split attention In several studies and experiments, Sweller and his associates found that learners had difficulty following some worked examples with diagrams separated from formulas, whereas learners using integrated diagrams were better able to process that information, and significantly improved their performance relative to their peers.The split-attention effect is not limited to geometry. Chandler and Sweller found that this effect extends to a variety of other disciplines, due to it being a limitation in human information processing. This is the result of high visual cognitive load due to poor instructional design.
Sulfonylurea herbicide Treatment of type 2 diabetes Sulfonylurea_herbicide > Uses > Medical uses > Treatment of type 2 diabetes They are widely used as antidiabetic drugs in the management of diabetes mellitus type 2. They act by increasing secretion of insulin from the beta cells in the pancreas.Sulfonylureas are ineffective where there is absolute deficiency of insulin production such as in type 1 diabetes or post-pancreatectomy.Sulfonylureas can be used to treat some types of neonatal diabetes. Historically, people with hyperglycemia and low blood insulin levels were diagnosed with type 1 diabetes by default, but it has been found that patients who receive this diagnosis before 6 months of age are often candidates for receiving sulfonylureas rather than insulin throughout life.A 2011 Cochrane systematic review evaluated the effects on treatment of Latent Autoimmune Diabetes in Adults (LADA) and found that Sulfonylureas did improve metabolic control of glucose at 3 and 12 months, even worsening HbA1c levels in some cases, when compared to insulin.
The Master Algorithm Reception The_Master_Algorithm > In the media > Reception A computer science educator stated in Times Higher Education that the examples are clear and accessible. In contrast, The Economist agreed Domingos "does a good job" but complained that he "constantly invents metaphors that grate or confuse". Kirkus Reviews praised the book, stating that "Readers unfamiliar with logic and computer theory will have a difficult time, but those who persist will discover fascinating insights. "A New Scientist review called it "compelling but rather unquestioning".
Nitrogen compounds Nitrides, azides, and nitrido complexes Nitrogen_compounds > Nitrides, azides, and nitrido complexes They are normally prepared by directly reacting a metal with nitrogen or ammonia (sometimes after heating), or by thermal decomposition of metal amides: 3 Ca + N2 → Ca3N2 3 Mg + 2 NH3 → Mg3N2 + 3 H2 (at 900 °C) 3 Zn(NH2)2 → Zn3N2 + 4 NH3Many variants on these processes are possible. The most ionic of these nitrides are those of the alkali metals and alkaline earth metals, Li3N (Na, K, Rb, and Cs do not form stable nitrides for steric reasons) and M3N2 (M = Be, Mg, Ca, Sr, Ba). These can formally be thought of as salts of the N3− anion, although charge separation is not actually complete even for these highly electropositive elements.
Foucault's measurements of the speed of light 1862 experiment Foucault's_measurements_of_the_speed_of_light > Foucault's determination of the speed of light > 1862 experiment Despite this limited path length, Foucault was able to measure the displacement of the slit image (less than 1 mm) with considerable accuracy. In addition, unlike the case with Fizeau's experiment (which required gauging the rotation rate of an adjustable-speed toothed wheel), he could spin the mirror at a constant, chronometrically determined speed. Foucault's measurement confirmed le Verrier's estimate. : 227–234 His 1862 figure for the speed of light (298000 km/s) was within 0.6% of the modern value.As seen in Figure 3, the displaced image of the source (slit) is at an angle 2θ from the source direction.
Pseudo-spectral method Polynomials Pseudo-spectral_method > Special pseudospectral schemes > Polynomials This basis, together with the quadrature points can then be used for the pseudo-spectral method. For the discussion of the error, note that if f {\displaystyle f} is well represented by N f {\displaystyle N_{f}} basis functions and V {\displaystyle V} is well represented by a polynomial of degree N V {\displaystyle N_{V}} , their product can be expanded in the first N f + N V {\displaystyle N_{f}+N_{V}} basis functions, and the pseudo-spectral method will give accurate results for that many basis functions. Such polynomials occur naturally in several standard problems. For example, the quantum harmonic oscillator is ideally expanded in Hermite polynomials, and Jacobi-polynomials can be used to define the associated Legendre functions typically appearing in rotational problems.
Browder fixed-point theorem Summary Browder_fixed-point_theorem The Browder fixed-point theorem is a refinement of the Banach fixed-point theorem for uniformly convex Banach spaces. It asserts that if K {\displaystyle K} is a nonempty convex closed bounded set in uniformly convex Banach space and f {\displaystyle f} is a mapping of K {\displaystyle K} into itself such that ‖ f ( x ) − f ( y ) ‖ ≤ ‖ x − y ‖ {\displaystyle \\|f(x)-f(y)\\|\leq \\|x-y\\|} (i.e. f {\displaystyle f} is non-expansive), then f {\displaystyle f} has a fixed point.
Affine connection Motivation and history Affine_connection > Motivation and history A smooth manifold is a mathematical object which looks locally like a smooth deformation of Euclidean space Rn: for example a smooth curve or surface looks locally like a smooth deformation of a line or a plane. Smooth functions and vector fields can be defined on manifolds, just as they can on Euclidean space, and scalar functions on manifolds can be differentiated in a natural way. However, differentiation of vector fields is less straightforward: this is a simple matter in Euclidean space, because the tangent space of based vectors at a point p can be identified naturally (by translation) with the tangent space at a nearby point q. On a general manifold, there is no such natural identification between nearby tangent spaces, and so tangent vectors at nearby points cannot be compared in a well-defined way. The notion of an affine connection was introduced to remedy this problem by connecting nearby tangent spaces. The origins of this idea can be traced back to two main sources: surface theory and tensor calculus.
DNA Polymerase I Mechanism DNA_Polymerase_I > Mechanism Its role in replication was proven when, in 1969, John Cairns isolated a viable polymerase I mutant that lacked the polymerase activity. Cairns' lab assistant, Paula De Lucia, created thousands of cell free extracts from E. coli colonies and assayed them for DNA-polymerase activity. The 3,478th clone contained the polA mutant, which was named by Cairns to credit "Paula" . It was not until the discovery of DNA polymerase III that the main replicative DNA polymerase was finally identified.
Object manager Summary Object_manager An object manager is a concept, and often a piece of software, found in object-oriented programming. The object manager provides rules for retention, naming and security of objects.
Glossary of electrical and electronics engineering M Glossary_of_electrical_and_electronics_engineering > M mechanical rectifier An electromechanical device for converting alternating current to direct current, using sets of contacts which operate in synchronism with the AC. mechatronics Combinations of mechanical systems with electronics for sensing and control. memristor A hypothetical non-linear passive two-terminal electrical component relating electric charge and magnetic flux linkage.
Foam cells Composition Foam_cell > Composition The oxidized LDL accumulates in the macrophages and other phagocytes, which are then known as foam cells. Foam cells form the fatty streaks of the plaques of atheroma in the tunica intima of arteries. Foam cells are not dangerous as such, but can become a problem when they accumulate at particular foci thus creating a necrotic centre of atherosclerosis.
Inline function Example Inline_function > Example An inline function can be written in C or C++ like this: Then, a statement such as the following: may be translated into (if the compiler decides to do the inlining, which typically requires optimization to be enabled): When implementing a sorting algorithm doing lots of swaps, this can increase the execution speed.
Laser converting Summary Laser_converting For industrial processes, Laser converting or laser digital converting is a production technology that enables device manufacturers to produce features that otherwise would be problematic or even impossible to die-cut, without the need for tooling. In contrast to traditional mechanical converting, laser digital converting utilizes the features of lasers and advance software technology to convert parts in extremely high accuracy. In production environment, the laser digital converting is the economics of scale when the production run is short, as there is virtually no 'up-front' cost associated with machine tools making and storage. Also, the turnaround time is minimal as it only involves software interpretation on the imported engineering diagram of the part.
Proline isomerization in epigenetics Cell signaling Proline_isomerization_in_epigenetics > Cell signaling Cell signaling involves many different processes and proteins. One of the most studied cell signaling phenomena involving proline is the interactions with p53 and prolyl isomerases, specifically Pin1. The protein p53, along with p63 and p73, are responsible for ensuring that alterations to the genome are corrected and for preventing the formation and growth of tumors. proline residues are found throughout the p53 proteins and without the phosphorylation and isomerization of specific Serine/Threonine-Proline motifs within p53, they cannot exhibit control over their target genes. The main signalling processes that are affected by p53 are apoptosis and cell cycle arrest, both of which are controlled by specific isomerization of the prolines in p53.
Methylazoxymethanol acetate Schizophrenia Methylazoxymethanol_acetate > MAM animal models > Schizophrenia In rat models, the specific effect of MAM on neural development depends on the gestational age of the subject. At the seventeenth gestational day (GD17), administration of MAM produces behavioral and histopathological patterns found in schizophrenia. The molecular mechanism behind this model is not fully known. Methylazoxymethanol acetate administered at GD17 reduces the thickness of the hippocampus and the thalamus.
Glucose oxidation reaction Regulated Enzymes in Glycolysis Glycolysis > Regulation > Regulated Enzymes in Glycolysis The regulated enzymes catalyzing these reactions perform these functions when they have been dephosphorylated through the action of insulin on the liver cells. Between meals, during fasting, exercise or hypoglycemia, glucagon and epinephrine are released into the blood.
Tracing just-in-time compilation Profiling phase Tracing_just-in-time_compilation > Technical details > Profiling phase The goal of profiling is to identify hot loops. This is often done by counting the number of iterations for every loop. After the count of a loop exceeds a certain threshold, the loop is considered to be hot, and tracing phase is entered.
Parameterized approximation algorithm Approximate kernelization Parameterized_approximation_algorithm > Approximate kernelization Kernelization is a technique used in fixed-parameter tractability to pre-process an instance of an NP-hard problem in order to remove "easy parts" and reveal the NP-hard core of the instance. A kernelization algorithm takes an instance I {\displaystyle I} and a parameter k {\displaystyle k} , and returns a new instance I ′ {\displaystyle I'} with parameter k ′ {\displaystyle k'} such that the size of I ′ {\displaystyle I'} and k ′ {\displaystyle k'} is bounded as a function of the input parameter k {\displaystyle k} , and the algorithm runs in polynomial time. An α {\displaystyle \alpha } -approximate kernelization algorithm is a variation of this technique that is used in parameterized approximation algorithms. It returns a kernel I ′ {\displaystyle I'} such that any β {\displaystyle \beta } -approximation in I ′ {\displaystyle I'} can be converted into an α β {\displaystyle \alpha \beta } -approximation to the input instance I {\displaystyle I} in polynomial time.
Correlation ratio Summary Correlation_ratio In statistics, the correlation ratio is a measure of the curvilinear relationship between the statistical dispersion within individual categories and the dispersion across the whole population or sample. The measure is defined as the ratio of two standard deviations representing these types of variation. The context here is the same as that of the intraclass correlation coefficient, whose value is the square of the correlation ratio.
Reverse Monte Carlo Issues with the RMC method Reverse_Monte_Carlo > Issues with the RMC method The RMC method suffers from a number of potential problems. The most notable problem is that often more than one qualitatively different model will give similar agreement with experimental data. For example, in the case of amorphous silicon, the integral of the first peak in the pair distribution function may imply an average atomic coordination number of 4. This might reflect the fact that all atoms have coordination number of 4, but similarly having half the atoms with coordination number of 3 and half with 5 will also be consistent with this data.
Homomorphism Examples Homomorphism > Examples {\displaystyle f(z)=\|z\|.} That is, f {\displaystyle f} is the absolute value (or modulus) of the complex number z {\displaystyle z} . Then f {\displaystyle f} is a homomorphism of groups, since it preserves multiplication: f ( z 1 z 2 ) = \| z 1 z 2 \| = \| z 1 \| \| z 2 \| = f ( z 1 ) f ( z 2 ) .
Energy return on investment Non-manmade energy inputs Energy_return_on_investment > Non-manmade energy inputs The natural or primary energy sources are not included in the calculation of energy invested, only the human-applied sources. For example, in the case of biofuels the solar insolation driving photosynthesis is not included, and the energy used in the stellar synthesis of fissile elements is not included for nuclear fission. The energy returned includes only human usable energy and not wastes such as waste heat. Nevertheless, heat of any form can be counted where it is actually used for heating. However the use of waste heat in district heating and water desalination in cogeneration plants is rare, and in practice it is often excluded in EROI analysis of energy sources.
Mastery learning Summary Mastery_learning Mastery learning (or, as it was initially called, "learning for mastery"; also known as "mastery-based learning") is an instructional strategy and educational philosophy, first formally proposed by Benjamin Bloom in 1968. Mastery learning maintains that students must achieve a level of mastery (e.g., 90% on a knowledge test) in prerequisite knowledge before moving forward to learn subsequent information. If a student does not achieve mastery on the test, they are given additional support in learning and reviewing the information and then tested again. This cycle continues until the learner accomplishes mastery, and they may then move on to the next stage.
Fibromyalgia syndrome Neuroendocrine system Fibromyalgia_syndrome > Pathophysiology > Nervous system > Neuroendocrine system Studies on the neuroendocrine system and HPA axis in fibromyalgia have been inconsistent. One study found fibromyalgia patients exhibited higher plasma cortisol, more extreme peaks and troughs, and higher rates of dexamethasone non-suppression. However, other studies have only found correlations between a higher cortisol awakening response and pain, and not any other abnormalities in cortisol. Increased baseline ACTH and increase in response to stress have been observed, hypothesized to be a result of decreased negative feedback.
HIV vaccine development Future work HIV_vaccine > Future work Scientists are researching novel strategies to develop a non-virulent live attenuated HIV-1 vaccine. For example, a genetically modified form of HIV has been created in which the virus's codons (a sequence of three nucleotides that form genetic code) are manipulated to rely on an unnatural amino acid for proper protein translation, which allows it to replicate. Because this amino acid is foreign to the human body, the virus cannot reproduce.
Bone marrow barrier Donation and transplantation Bone_marrow_stroma > Clinical significance > Donation and transplantation The patient's own marrow is first killed off with drugs or radiation, and then the new stem cells are introduced. Before radiation therapy or chemotherapy in cases of cancer, some of the patient's hematopoietic stem cells are sometimes harvested and later infused back when the therapy is finished to restore the immune system.Bone marrow stem cells can be induced to become neural cells to treat neurological illnesses, and can also potentially be used for the treatment of other illnesses, such as inflammatory bowel disease. In 2013, following a clinical trial, scientists proposed that bone marrow transplantation could be used to treat HIV in conjunction with antiretroviral drugs; however, it was later found that HIV remained in the bodies of the test subjects.
Tree structure Terminology and properties Tree_structure > Terminology and properties The tree elements are called "nodes". The lines connecting elements are called "branches". Nodes without children are called leaf nodes, "end-nodes", or "leaves".
Input validation Validation types Validation_rule > Validation types For example, an input box accepting numeric data may reject the letter 'O'.File existence check Checks that a file with a specified name exists. This check is essential for programs that use file handling.Format check Checks that the data is in a specified format (template), e.g., dates have to be in the format YYYY-MM-DD. Regular expressions may be used for this kind of validation.Presence check Checks that data is present, e.g., customers may be required to have an email address.Range check Checks that the data is within a specified range of values, e.g., a probability must be between 0 and 1.Referential integrity Values in two relational database tables can be linked through foreign key and primary key. If values in the foreign key field are not constrained by internal mechanisms, then they should be validated to ensure that the referencing table always refers to a row in the referenced table.Spelling and grammar check Looks for spelling and grammatical errors.Uniqueness check Checks that each value is unique. This can be applied to several fields (i.e. Address, First Name, Last Name).Table look up check A table look up check compares data to a collection of allowed values.
Lovelock theory of gravity Other contexts Lovelock_theory_of_gravity > Other contexts Because Lovelock action contains, among others, the quadratic Gauss–Bonnet term (i.e. the four-dimensional Euler characteristic extended to D dimensions), it is usually said that Lovelock theory resembles string-theory-inspired models of gravity. This is because a quadratic term is present in the low energy effective action of heterotic string theory, and it also appears in six-dimensional Calabi–Yau compactifications of M-theory. In the mid 1980s, a decade after Lovelock proposed his generalization of the Einstein tensor, physicists began to discuss the quadratic Gauss–Bonnet term within the context of string theory, with particular attention to its property of being ghost-free in Minkowski space. The theory is known to be free of ghosts about other exact backgrounds as well, e.g. about one of the branches of the spherically symmetric solution found by Boulware and Deser in 1985. In general, Lovelock's theory represents a very interesting scenario to study how the physics of gravity is corrected at short distance due to the presence of higher order curvature terms in the action, and in the mid-2000s the theory was considered as a testing ground to investigate the effects of introducing higher-curvature terms in the context of AdS/CFT correspondence.
Mathematical equations Differential equations Mathematical_equations > Differential equations In pure mathematics, differential equations are studied from several different perspectives, mostly concerned with their solutions — the set of functions that satisfy the equation. Only the simplest differential equations are solvable by explicit formulas; however, some properties of solutions of a given differential equation may be determined without finding their exact form. If a self-contained formula for the solution is not available, the solution may be numerically approximated using computers. The theory of dynamical systems puts emphasis on qualitative analysis of systems described by differential equations, while many numerical methods have been developed to determine solutions with a given degree of accuracy.
Higher-spin theory Reconstruction Higher-spin_theory > Various approaches to higher-spin theories > Reconstruction The higher-spin AdS/CFT correspondence can be used in the reverse order – one can attempt to build the interaction vertices of the higher-spin theory in such a way that they reproduce the correlation functions of a given conjectural CFT dual. This approach takes advantage of the fact that the kinematics of AdS theories is, to some extent, equivalent to the kinematics of conformal field theories in one dimension lower – one has exactly the same number of independent structures on both sides. In particular, the cubic part of the action of the Type-A higher-spin theory was found by inverting the three-point functions of the higher-spin currents in the free scalar CFT. Some quartic vertices have been reconstructed too.
Magnetization Summary Magnetization_reversal Magnetization also describes how a material responds to an applied magnetic field as well as the way the material changes the magnetic field, and can be used to calculate the forces that result from those interactions. It can be compared to electric polarization, which is the measure of the corresponding response of a material to an electric field in electrostatics. Physicists and engineers usually define magnetization as the quantity of magnetic moment per unit volume. It is represented by a pseudovector M.
Bayesian methods Elementary Bayesian_analysis > Further reading > Elementary (2008). Bayesian Methods for Data Analysis, Third Edition. Boca Raton, FL: Chapman and Hall/CRC.
Charles Kittel Works Charles_Kittel > Works Berkeley Physics Course. Mechanics. Vol.
Italophilia Modern era Italophilia > Modern era Her methods are in use today in schools throughout the world. Toward the end of the 19th century, mathematicians Gregorio Ricci-Curbastro and Tullio Levi-Civita developed tensor calculus, which provided the mathematical framework for Einstein's General Theory of Relativity in the early 20th century. In the early 20th century Pirandello, a Nobel Laureate, was the first European playwright to radically question the structures of traditional theatre.
Parallel running Examples of parallel running implementation Parallel_running > Examples of parallel running implementation The new system is implemented using parallel running strategy so all accounts and invoices have to be handled both in the new and old systems. If the new system does not function correctly, data from the old system can be used. However, everything needs to be done twice, which will slow down the accounts department and cost money in hiring more staff. This system is safe and the new system can be precisely tested as every transaction can be compared with the result from the old system. It is also applied when using a new computerized system to create brief reference records and generate orders but maintaining the old manual system for final financial control until the new system has been confirmed that it can function correctly.
Aerodynamic potential-flow code Summary Aerodynamic_potential-flow_code In fluid dynamics, aerodynamic potential flow codes or panel codes are used to determine the fluid velocity, and subsequently the pressure distribution, on an object. This may be a simple two-dimensional object, such as a circle or wing, or it may be a three-dimensional vehicle. A series of singularities as sources, sinks, vortex points and doublets are used to model the panels and wakes. These codes may be valid at subsonic and supersonic speeds.
Wallpaper group Symmetries of patterns Plane_group > Symmetries of patterns A symmetry of a pattern is, loosely speaking, a way of transforming the pattern so that it looks exactly the same after the transformation. For example, translational symmetry is present when the pattern can be translated (in other words, shifted) some finite distance and appear unchanged. Think of shifting a set of vertical stripes horizontally by one stripe. The pattern is unchanged.
Random variate Definition Deviate_(statistics) > Definition Devroye defines a random variate generation algorithm (for real numbers) as follows: Assume that Computers can manipulate real numbers. Computers have access to a source of random variates that are uniformly distributed on the closed interval . Then a random variate generation algorithm is any program that halts almost surely and exits with a real number x. This x is called a random variate.
Constructionism (learning theory) Computer programming languages Constructionism_(learning_theory) > Computer programming languages Its creators were Wally Feurzeig, Cynthia Solomon, and Papert. Smalltalk is an object-oriented language that was designed and created at Xerox PARC by a team led by Alan Kay. AgentSheets is an early block-based programming environment for kids to create games and simulations.
Several complex variables Historical perspective Functions_of_several_complex_variables > Historical perspective Many examples of such functions were familiar in nineteenth-century mathematics; abelian functions, theta functions, and some hypergeometric series, and also, as an example of an inverse problem; the Jacobi inversion problem. Naturally also same function of one variable that depends on some complex parameter is a candidate. The theory, however, for many years didn't become a full-fledged field in mathematical analysis, since its characteristic phenomena weren't uncovered. The Weierstrass preparation theorem would now be classed as commutative algebra; it did justify the local picture, ramification, that addresses the generalization of the branch points of Riemann surface theory.
Monocistronic mRNA Eukaryotic mRNA turnover Monocistronic_mRNA > Degradation > Eukaryotic mRNA turnover Inside eukaryotic cells, there is a balance between the processes of translation and mRNA decay. Messages that are being actively translated are bound by ribosomes, the eukaryotic initiation factors eIF-4E and eIF-4G, and poly(A)-binding protein. eIF-4E and eIF-4G block the decapping enzyme (DCP2), and poly(A)-binding protein blocks the exosome complex, protecting the ends of the message. The balance between translation and decay is reflected in the size and abundance of cytoplasmic structures known as P-bodies.
Microbial cooperation Quorum sensing Microbial_cooperation > Other microbial interactions > Quorum sensing This important link between quorum sensing and anaerobiosis has a significant impact on production of virulence factors of this organism. It is hoped that the therapeutic enzymatic degradation of the signaling molecules will prevent the formation of such biofilms and possibly weaken established biofilms. Disrupting the signalling process in this way is called quorum inhibition.
Faster-than-light neutrino anomaly The measurement Faster-than-light_neutrino_anomaly > The measurement The neutrinos in the experiment emerged at CERN and flew to the OPERA detector. The researchers divided this distance by the speed of light in vacuum to predict what the neutrino travel time should be. They compared this expected value to the measured travel time.
Computer Program C++ Computer_code > Programming paradigms and languages > Imperative languages > C++ An assigned function is then referred to as a method, member function, or operation. Object-oriented programming is executing operations on objects.Object-oriented languages support a syntax to model subset/superset relationships. In set theory, an element of a subset inherits all the attributes contained in the superset.
Mouse-Ear Cress Non-Mendelian inheritance controversy Thale_cress > Use as a model organism > Genetics > Non-Mendelian inheritance controversy In 2005, scientists at Purdue University proposed that A. thaliana possessed an alternative to previously known mechanisms of DNA repair, producing an unusual pattern of inheritance, but the phenomenon observed (reversion of mutant copies of the HOTHEAD gene to a wild-type state) was later suggested to be an artifact because the mutants show increased outcrossing due to organ fusion.
Lechler The 1970s: the start of a systemic model in product formulation and the organisation Lechler > The 1970s: the start of a systemic model in product formulation and the organisation The 1970s marked the beginning of modernisation for Lechler: the management team got renewed with the entry of the sons of the two owners (engineer Noubar Manoukian and Renato Bruschi), and the organisation and technical structures were reinforced by the hiring of numerous technical staff and some graduates. The new facilities in Como-Rebbio were a reflection and a mirror of this renewal and a true industrial landmark. The new facilities embodied the convergence of the innovative industrial engineering drive of engineer Noubar Manoukian and the architectural vision and talent rooted in Italian rationalism of architect Manouk Manoukian. The company's modernisation was accompanied and supported by the progressive introduction of information technology across the company's functions: R&D, production, finance. The rationalisation and integration of the formulation and colour inventory into a systemic platform fit for a variety of tinting equipment responded to the increasing demand for diversified product and colour ranges (Isofan, BSB, Extralucido, Isoakryl and RS systems).
Oxidative phosphorylation Chemiosmosis ATP_generation > Chemiosmosis It has two components: a difference in proton concentration (a H+ gradient, ΔpH) and a difference in electric potential, with the N-side having a negative charge.ATP synthase releases this stored energy by completing the circuit and allowing protons to flow down the electrochemical gradient, back to the N-side of the membrane. The electrochemical gradient drives the rotation of part of the enzyme's structure and couples this motion to the synthesis of ATP. The two components of the proton-motive force are thermodynamically equivalent: In mitochondria, the largest part of energy is provided by the potential; in alkaliphile bacteria the electrical energy even has to compensate for a counteracting inverse pH difference.
Marginal revenue Definition Marginal_revenue > Definition Marginal revenue is equal to the ratio of the change in revenue for some change in quantity sold to that change in quantity sold. This can be formulated as: M R = Δ T R Δ Q {\displaystyle MR={\frac {\Delta TR}{\Delta Q}}} This can also be represented as a derivative when the change in quantity sold becomes arbitrarily small. Define the revenue function to be R ( Q ) = P ( Q ) ⋅ Q , {\displaystyle R(Q)=P(Q)\cdot Q,} where Q is output and P(Q) is the inverse demand function of customers.
Euclidean traveling salesman problem Pairwise exchange Euclidean_traveling_salesman_problem > Computing a solution > Heuristic and approximation algorithms > Pairwise exchange If we start with an initial solution made with a greedy algorithm, the average number of moves greatly decreases again and is O ( n ) {\displaystyle O(n)} . For random starts however, the average number of moves is O ( n log ⁡ ( n ) ) {\displaystyle O(n\log(n))} . However whilst in order this is a small increase in size, the initial number of moves for small problems is 10 times as big for a random start compared to one made from a greedy heuristic. This is because such 2-opt heuristics exploit 'bad' parts of a solution such as crossings. These types of heuristics are often used within Vehicle routing problem heuristics to reoptimize route solutions.
Metal bondage Materials Metal_bondage > Materials Soft objects such as these can also be used for binding in front of the restrained partner's eyes, temporarily blinding them. "Verbal bondage" is bondage without physical restraint; the subject is simply given orders not to move, or only move in a restrained fashion. The technique is sometimes known as "honor bondage".
Lazy tongs Drafting Pantograph > Uses > Drafting The original use of the pantograph was for copying and scaling line drawings. Modern versions are sold as technical toys.
RNA silencing Background RNA_silencing > Background RNA silencing describes several mechanistically related pathways which are involved in controlling and regulating gene expression. RNA silencing pathways are associated with the regulatory activity of small non-coding RNAs (approximately 20–30 nucleotides in length) that function as factors involved in inactivating homologous sequences, promoting endonuclease activity, translational arrest, and/or chromatic or DNA modification. In the context in which the phenomenon was first studied, small RNA was found to play an important role in defending plants against viruses. For example, these studies demonstrated that enzymes detect double-stranded RNA (dsRNA) not normally found in cells and digest it into small pieces that are not able to cause disease.While some functions of RNA silencing and its machinery are understood, many are not.
Japanese tea utensils Mizusashi Japanese_tea_utensils > Water containers > Mizusashi A mizusashi (水指) is a lidded container for fresh cold water used by the host in the tea room during ceremonies. The water is mainly used to replenish the water in the kama at the end of certain ceremonies. Mizusashi are generally made of ceramic, but wooden, glass and metal mizusashi are also used. If the mizusashi is ceramic and has a matching lid of the same ceramic, the lid is referred to as a tomobuta, or "matching lid".
Synthetic colorant Summary Synthetic_dye A colorant is any substance that changes the spectral transmittance or reflectance of a material. Synthetic colorants are those created in a laboratory or industrial setting. The production and improvement of colorants was a driver of the early synthetic chemical industry, in fact many of today's largest chemical producers started as dye-works in the late 19th or early 20th centuries, including Bayer AG(1863). Synthetics are extremely attractive for industrial and aesthetic purposes as they have they often achieve higher intensity and color fastness than comparable natural pigments and dyes used since ancient times.
Bioethics Medical ethics Biomedical_ethics > Medical ethics Medical ethics is concerned with the duties that doctors, hospitals, and other healthcare providers have to patients, society, and other health professionals. The health profession has a set of ethical standards that are relevant to various organizations of health workers and medical facilities. Ethics are never stagnant and always relevant. What is seen as acceptable ethics now may not be so one hundred years ago. The hospital administrator is required to have a thorough awareness of their moral and legal obligations.
Conventional undercarriage Advantages Conventional_landing_gear > Advantages The tailwheel configuration offers several advantages over the tricycle landing gear arrangement, which make tailwheel aircraft less expensive to manufacture and maintain. Due to its position much further from the center of gravity, a tailwheel supports a smaller part of the aircraft's weight allowing it to be made much smaller and lighter than a nosewheel. As a result, the smaller wheel weighs less and causes less parasitic drag. Because of the way airframe loads are distributed while operating on rough ground, tailwheel aircraft are better able to sustain this type of use over a long period of time, without cumulative airframe damage occurring.
Symmetries in quantum mechanics Gauge theory Symmetries_in_quantum_mechanics > Symmetries in quantum field theory and particle physics > Gauge theory In quantum electrodynamics, the local symmetry group is U(1) and is abelian. In quantum chromodynamics, the local symmetry group is SU(3) and is non-abelian. The electromagnetic interaction is mediated by photons, which have no electric charge.
Compiler construction History Compiler_back-end > History In many application domains, the idea of using a higher-level language quickly caught on. Because of the expanding functionality supported by newer programming languages and the increasing complexity of computer architectures, compilers became more complex. DARPA (Defense Advanced Research Projects Agency) sponsored a compiler project with Wulf's CMU research team in 1970.
PDMS (software) Summary PDMS_(software) PDMS (Plant Design Management System) as it is known in the 3D CAD industry, is a customizable, multi-user and multi-discipline, engineer controlled design software package for engineering, design and construction projects in offshore and onshore. The Computer-Aided Design Centre (or CADCentre as it was more commonly referred to, and later formally became) was created in Cambridge, England, UK in 1967 by the UK Ministry of Technology. Its mission was to develop computer-aided design techniques and promote their take-up by British industry. The centre carried out much pioneering CAD research, and many of its early staff members went on to become prominent in the worldwide CAD community, such as brothers Dick Newell and Martin Newell.Dick Newell oversaw the creation of the Plant Design Management System (PDMS) for 3D process plant design.
Cross-validation (statistics) Motivation Out_of_sample_testing > Motivation Assume a model with one or more unknown parameters, and a data set to which the model can be fit (the training data set). The fitting process optimizes the model parameters to make the model fit the training data as well as possible. If an independent sample of validation data is taken from the same population as the training data, it will generally turn out that the model does not fit the validation data as well as it fits the training data. The size of this difference is likely to be large especially when the size of the training data set is small, or when the number of parameters in the model is large. Cross-validation is a way to estimate the size of this effect.
Caustic Soda Reaction with acidic oxides Caustic_Soda > Properties > Chemical properties > Reaction with acidic oxides Sodium hydroxide also reacts with acidic oxides, such as sulfur dioxide. Such reactions are often used to "scrub" harmful acidic gases (like SO2 and H2S) produced in the burning of coal and thus prevent their release into the atmosphere. For example, 2 NaOH + SO2 → Na2SO3 + H2O
Multi-agent system Summary Multi-agent_system The goal of an ABM is to search for explanatory insight into the collective behavior of agents (which don't necessarily need to be "intelligent") obeying simple rules, typically in natural systems, rather than in solving specific practical or engineering problems. The terminology of ABM tends to be used more often in the science, and MAS in engineering and technology. Applications where multi-agent systems research may deliver an appropriate approach include online trading, disaster response, target surveillance and social structure modelling.
Warfarin sodium Pharmacokinetics Warfarin_sodium > Pharmacology > Pharmacokinetics Warfarin consists of a racemic mixture of two active enantiomers—R- and S- forms—each of which is cleared by different pathways. S-warfarin is two to five times more potent than the R-isomer in producing an anticoagulant response. Both the enantiomers of warfarin undergo CYP-mediated metabolism by many different CYPs to form 3',4',6,7,8 and 10-hydroxy warfarin metabolites, major being 7-OH warfarin formed from S-warfarin by CYP2C9 and 10-OH warfarin from R-warfarin by CYP3A4.Warfarin is slower-acting than the common anticoagulant heparin, though it has a number of advantages. Heparin must be given by injection, whereas warfarin is available orally.
Dot-decimal notation Texts Dot-decimal_notation > Texts Dot-decimal notation is often used for sections within a large text. This was standardized in ISO 2145.
C10H18O Summary C10H18O The molecular formula C10H18O (molar mass: 154.25 g/mol) may refer to: Borneol Citronellal Eucalyptol 2-Decenal Fenchol Geraniol Grandisol Lavandulol Linalool Menthone Myrcenol Nerol 2-Pinanol Rose oxide Terpinen-4-ol Terpineol
Reduced gravity Summary Reduced_gravity Near a black hole, such tidal effects can be very strong, meeting to spaghettification. In the case of the Earth, the effects are minor, especially on objects of relatively small dimensions (such as the human body or a spacecraft) and the overall sensation of weightlessness in these cases is preserved. This condition is known as microgravity, and it prevails in orbiting spacecraft.
Glossary of industrial automation A Glossary_of_industrial_automation > A analog output channel amplifierAn amplifier attached to one or more analog output channels, that adapts the output signal range of the digital-to-analog converter to the signal level necessary to control the technical process. analog representationA representation of the value of a variable by a physical quantity that is considered to be continuously variable, the magnitude of the physical quantity being made directly proportional to the variable or to a suitable function of the variable. analogue anplifierAmplifier the output of which is continuously variable with the applied control signal.
Inverse problem Numerical solution of the optimization problem Forward_problem > Linear inverse problems > Mathematical and computational aspects > Numerical solution of the optimization problem The numerical method to be used for solving the optimization problem depends in particular on the cost required for computing the solution F p {\displaystyle Fp} of the forward problem. Once chosen the appropriate algorithm for solving the forward problem (a straightforward matrix-vector multiplication may be not adequate when matrix F {\displaystyle F} is huge), the appropriate algorithm for carrying out the minimization can be found in textbooks dealing with numerical methods for the solution of linear systems and for the minimization of quadratic functions (see for instance Ciarlet or Nocedal). Also, the user may wish to add physical constraints to the models: In this case, they have to be familiar with constrained optimization methods, a subject in itself.
Space-time continuum Reference frames Lorentz_interval > Spacetime in special relativity > Reference frames To determine the angle of this tilt, we recall that the slope of the world line of a light pulse is always ±1. Fig. 2-3c presents a spacetime diagram from the viewpoint of observer O′. Event P represents the emission of a light pulse at x′ = 0, ct′ = −a.
Loop (graph theory) Summary Loop_(graph_theory) In graph theory, a loop (also called a self-loop or a buckle) is an edge that connects a vertex to itself. A simple graph contains no loops. Depending on the context, a graph or a multigraph may be defined so as to either allow or disallow the presence of loops (often in concert with allowing or disallowing multiple edges between the same vertices): Where graphs are defined so as to allow loops and multiple edges, a graph without loops or multiple edges is often distinguished from other graphs by calling it a simple graph. Where graphs are defined so as to disallow loops and multiple edges, a graph that does have loops or multiple edges is often distinguished from the graphs that satisfy these constraints by calling it a multigraph or pseudograph.In a graph with one vertex, all edges must be loops. Such a graph is called a bouquet.
Adversarial machine learning Carlini & Wagner (C&W) Adversarial_machine_learning > Specific attack types > Adversarial examples > White box attacks > Carlini & Wagner (C&W) In an effort to analyze existing adversarial attacks and defenses, researchers at the University of California, Berkeley, Nicholas Carlini and David Wagner in 2016 propose a faster and more robust method to generate adversarial examples.The attack proposed by Carlini and Wagner begins with trying to solve a difficult non-linear optimization equation: Here the objective is to minimize the noise ( δ {\textstyle \delta } ), added to the original input x {\textstyle x} , such that the machine learning algorithm ( C {\textstyle C} ) predicts the original input with delta (or x + δ {\textstyle x+\delta } ) as some other class t {\textstyle t} . However instead of directly the above equation, Carlini and Wagner propose using a new function f {\textstyle f} such that: This condenses the first equation to the problem below: and even more to the equation below: Carlini and Wagner then propose the use of the below function in place of f {\textstyle f} using Z {\textstyle Z} , a function that determines class probabilities for given input x {\textstyle x} . When substituted in, this equation can be thought of as finding a target class that is more confident than the next likeliest class by some constant amount: When solved using gradient descent, this equation is able to produce stronger adversarial examples when compared to fast gradient sign method that is also able to bypass defensive distillation, a defense that was once proposed to be effective against adversarial examples.
Case study Case selection and structure Case_study > Research designs > Case selection and structure For example, outlier cases (those which are extreme, deviant or atypical) can reveal more information than the potentially representative case. A case may also be chosen because of the inherent interest of the case or the circumstances surrounding it. Alternatively, it may be chosen because of researchers' in-depth local knowledge; where researchers have this local knowledge they are in a position to "soak and poke" as Richard Fenno put it, and thereby to offer reasoned lines of explanation based on this rich knowledge of setting and circumstances.
Orthopedic pathology Degenerative Diseases Orthopedic_pathology > Types of Disorders > Degenerative Diseases Degenerative diseases are classified due to their nature of destroying Motor neurons, responsible for the movement of all muscle groups within the body. Common examples of degenerative diseases are Parkinson's disease and Muscular Dystrophy.
HTML code Attributes HyperText_Markup_Language > Markup > Elements > Attributes For example, an HTML document might semantically use the designation to indicate that all elements with this class value are subordinate to the main text of the document. In presentation, such elements might be gathered together and presented as footnotes on a page instead of appearing in the place where they occur in the HTML source. Class attributes are used semantically in microformats.
Matrix representation of conic sections Axes Matrix_representation_of_conic_sections > Central conics > Axes By the principal axis theorem, the two eigenvectors of the matrix of the quadratic form of a central conic section (ellipse or hyperbola) are perpendicular (orthogonal to each other) and each is parallel to (in the same direction as) either the major or minor axis of the conic. The eigenvector having the smallest eigenvalue (in absolute value) corresponds to the major axis.Specifically, if a central conic section has center (xc, yc) and an eigenvector of A33 is given by v(v1, v2) then the principal axis (major or minor) corresponding to that eigenvector has equation,
Origin of replication Replicon model Replication_origin > Replicon model Although replicators and origins can be spaced physically apart on chromosomes, they often co-localize or are located in close proximity; for simplicity, we will thus refer to both elements as ‘origins’ throughout this review. Taken together, the discovery and isolation of origin sequences in various organisms represents a significant milestone towards gaining mechanistic understanding of replication initiation. In addition, these accomplishments had profound biotechnological implications for the development of shuttle vectors that can be propagated in bacterial, yeast and mammalian cells.
Pipeline burst cache Pipelining mode Pipeline_burst_cache > Principles of operation > Pipelining mode In this mode, one memory value can be accessed in Cache at the same time that another memory value is accessed in DRAM. The pipelining operation suggests that the transfer of data and instructions from or to the cache is divided into stages. Each stage is kept busy by one operation all the time. This is just like the concept used in an assembly line. This operation overcame the defects of sequential memory operations which involved a lot of time wastage and decrease in the processor speed.
PI controller Reciprocal gain, a.k.a. proportional band PD_controller > Alternative nomenclature and forms > Reciprocal gain, a.k.a. proportional band In many cases, the manipulated variable output by the PID controller is a dimensionless fraction between 0 and 100% of some maximum possible value, and the translation into real units (such as pumping rate or watts of heater power) is outside the PID controller. The process variable, however, is in dimensioned units such as temperature. It is common in this case to express the gain K p {\displaystyle K_{p}} not as "output per degree", but rather in the reciprocal form of a proportional band 100 / K p {\displaystyle 100/K_{p}} , which is "degrees per full output": the range over which the output changes from 0 to 1 (0% to 100%). Beyond this range, the output is saturated, full-off or full-on. The narrower this band, the higher the proportional gain.
Space-charge limited current In semiconductors Space-charge_limited_current > Space-charge-limited current > In semiconductors In semiconductors and insulating materials, an electric field causes charged particles, electrons, to reach a specific drift velocity that is parallel to the direction of the field. This is different from the behavior of the free charged particles in a vacuum, in which a field accelerates the particle. The proportionality factor between the magnitudes of the drift velocity, v {\displaystyle v} , and the electric field, E {\displaystyle {\mathcal {E}}} , is called the mobility, μ {\displaystyle \mu } :
Ampère's force law Notable derivations of Ampère's force law Ampère's_force_law > Notable derivations of Ampère's force law 309-332 (in French) Alfred O'Rahilly's 1938 derivation: Electromagnetic Theory: A Critical Examination of Fundamentals vol. 1, pp. 102–104 (cf. the following pages, too)
Galilean equivalence Development of gravitational theory Galilean_equivalence > Development of gravitational theory The direction or vector of acceleration equivalence on the surface of the earth is "up" or directly opposite the center of the planet while the vector of acceleration in a spaceship is directly opposite from the mass ejected by its thrusters. From this principle, Einstein deduced that free-fall is inertial motion. Objects in free-fall do not experience being accelerated downward (e.g. toward the earth or other massive body) but rather weightlessness and no acceleration.
Epigenetic inheritance In Humans Transgenerational_epigenetic_inheritance > Examples of TEI > In Humans These maternal risk factors and environmental stressors coupled with transgenerational epigenetic changes can result in prolonged insult to the signaling pathways associated with the vascular development during fetal stages, thus increasing the likelihood of having PAH.One study has shown childhood abuse, which is defined as "sexual contact, severe physical abuse and/or severe neglect," leads to epigenetic modifications of glucocorticoid receptor expression. Glucocorticoid receptor expression plays a vital role in hypothalamic-pituitary-adrenal (HPA) activity.
Hardware stack Compile-time memory management Stack_(abstract_data_type) > Applications of stacks > Compile-time memory management This type of stack is used implicitly by the compiler to support CALL and RETURN statements (or their equivalents) and is not manipulated directly by the programmer. Some programming languages use the stack to store data that is local to a procedure. Space for local data items is allocated from the stack when the procedure is entered, and is deallocated when the procedure exits. The C programming language is typically implemented in this way. Using the same stack for both data and procedure calls has important security implications (see below) of which a programmer must be aware in order to avoid introducing serious security bugs into a program.
Nested function definition Higher-order functions Nested_function > Purpose > Other uses > Higher-order functions As in most languages functions are valid return types, it is possible to create a nested function that accesses a set of parameters from the outer function, that is a closure, and have that function be the outer function's return value. Thus it is possible to return a function that is set to fulfill a certain task with little or no further parameters given to it, which can increase performance quite significantly.
Cholangiocyte Function Cholangiocyte > Function In the healthy liver, cholangiocytes contribute to bile secretion via release of bicarbonate and water. Several hormones and locally acting mediators are known to contribute to cholangiocyte fluid/electrolyte secretion. These include secretin, acetylcholine, ATP, and bombesin.

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