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Noise measurement Summary Noise_measurement In acoustics, noise measurement can be for the purpose of measuring environmental noise or measuring noise in the workplace. Applications include monitoring of construction sites, aircraft noise, road traffic noise, entertainment venues and neighborhood noise. One of the definitions of noise covers all "unwanted sounds". When sound levels reach a high enough intensity, the sound, whether it is wanted or unwanted, may be damaging to hearing.
Click tracking Methods of click tracking Click_tracking > Methods of click tracking This helps with determining patterns in the users’ navigational behaviors. Some features that can be observed include how long users viewed pages for, click path lengths, and the number of clicks.
Receptacle tester History Receptacle_tester > History An early reference that describes the typical outlet tester circuit was published in Popular Mechanics in the March issue of 1967, and consists of two 27 kΩ resistors, one 100 kΩ resistor, and three NE-51 neon lamp bulbs with 100 kΩ resistors.
Selenium(IV) oxychloride Preparation and reactions Selenium(IV)_oxychloride > Preparation and reactions Selenium oxydichloride can be prepared by several methods, and a common one involves the conversion of selenium dioxide to dichloroselenious acid followed by dehydration: SeO2 + 2 HCl → Se(OH)2Cl2 Se(OH)2Cl2 → SeOCl2 + H2OThe original synthesis involved the redistribution reaction of selenium dioxide and selenium tetrachloride. The compound hydrolyzes readily to form hydrogen chloride and selenium dioxide.
Squared error loss Quadratic loss function Loss_functions > Example > Quadratic loss function This is also known as the squared error loss (SEL).Many common statistics, including t-tests, regression models, design of experiments, and much else, use least squares methods applied using linear regression theory, which is based on the quadratic loss function. The quadratic loss function is also used in linear-quadratic optimal control problems. In these problems, even in the absence of uncertainty, it may not be possible to achieve the desired values of all target variables. Often loss is expressed as a quadratic form in the deviations of the variables of interest from their desired values; this approach is tractable because it results in linear first-order conditions. In the context of stochastic control, the expected value of the quadratic form is used.
Earle–Hamilton fixed-point theorem Proof Earle–Hamilton_fixed_point_theorem > Proof The Carathéodory metric is defined by d ( x , y ) = inf γ ( 0 ) = x , γ ( 1 ) = y ℓ ( γ ) {\displaystyle \displaystyle {d(x,y)=\inf _{\gamma (0)=x,\gamma (1)=y}\ell (\gamma )}} for x and y in D. It is a continuous function on D x D for the norm topology. If the diameter of D is less than R then, by taking suitable holomorphic functions g of the form g ( z ) = a ( z ) + b {\displaystyle \displaystyle {g(z)=a(z)+b}} with a in X* and b in C, it follows that α ( z , v ) ≥ ‖ v ‖ / R , {\displaystyle \displaystyle {\alpha (z,v)\geq \\|v\\|/R,}} and hence that d ( x , y ) ≥ ‖ x − y ‖ / R . {\displaystyle \displaystyle {d(x,y)\geq \\|x-y\\|/R.}}
Anti–computer forensics Attacks against computer forensics Anti–computer_forensics > Attacks against computer forensics Hashes are created by the forensic examination software to verify the integrity of the image. One of the recent anti-tool techniques targets the integrity of the hash that is created to verify the image. By affecting the integrity of the hash, any evidence that is collected during the subsequent investigation can be challenged.
Base of lung Obstructive lung diseases Oblique_fissure > Clinical significance > Obstructive lung diseases Asthma, bronchiectasis, and chronic obstructive pulmonary disease (COPD) that includes chronic bronchitis, and emphysema, are all obstructive lung diseases characterised by airway obstruction. This limits the amount of air that is able to enter alveoli because of constriction of the bronchial tree, due to inflammation. Obstructive lung diseases are often identified because of symptoms and diagnosed with pulmonary function tests such as spirometry. Many obstructive lung diseases are managed by avoiding triggers (such as dust mites or smoking), with symptom control such as bronchodilators, and with suppression of inflammation (such as through corticosteroids) in severe cases.
Human overpopulation Resource depletion Human_overpopulation > Proposed impacts > Resource depletion Some commentary has attributed depletion of non-renewable resources, such as land, food and water, to overpopulation and suggested it could lead to a diminished quality of human life. Ecologist David Pimentel was one such proponent, saying "with the imbalance growing between population numbers and vital life sustaining resources, humans must actively conserve cropland, freshwater, energy, and biological resources. There is a need to develop renewable energy resources.
Corecursion Factorial Corecursion > Examples > Factorial This may be concretely implemented as a generator. Symbolically, noting that computing next factorial value requires keeping track of both n and f (a previous factorial value), this can be represented as: n , f = ( 0 , 1 ): ( n + 1 , f × ( n + 1 ) ) {\displaystyle n,f=(0,1):(n+1,f\times (n+1))} or in Haskell, meaning, "starting from n , f = 0 , 1 {\displaystyle n,f=0,1} , on each step the next values are calculated as n + 1 , f × ( n + 1 ) {\displaystyle n+1,f\times (n+1)} ". This is mathematically equivalent and almost identical to the recursive definition, but the + 1 {\displaystyle +1} emphasizes that the factorial values are being built up, going forwards from the starting case, rather than being computed after first going backwards, down to the base case, with a − 1 {\displaystyle -1} decrement.
Navier–Stokes existence and smoothness The Navier–Stokes equations Navier–Stokes_existence_and_smoothness > The Navier–Stokes equations One way to understand the nonlinearity of the Navier–Stokes equations is to consider the term (v · ∇)v in the equations. This term represents the acceleration of the fluid, and it is a product of the velocity vector v and the gradient operator ∇. Because the gradient operator is a linear operator, the term (v · ∇)v is nonlinear in the velocity vector v. This means that the acceleration of the fluid depends on the magnitude and direction of the velocity, as well as the spatial distribution of the velocity within the fluid.
Gear Cube Variations Gear_Cube > Variations A common issue while solving this cube is having the entire puzzle complete except for the newly added stickers being mismatched with different sides.Even Less Gears: The only 3x3 type of Gear Cube with a total of four gears. It takes another four gears out and replaces them with standard edges. As the number of gears get fewer and fewer, the difficulty level rises.
Per Enflo Grothendieck's formulation of the approximation problem Per_Enflo > Enflo's contributions to functional analysis and operator theory > The basis problem and Mazur's goose > Grothendieck's formulation of the approximation problem Grothendieck's work on the theory of Banach spaces and continuous linear operators introduced the approximation property. A Banach space is said to have the approximation property, if every compact operator is a limit of finite-rank operators. The converse is always true.In a long monograph, Grothendieck proved that if every Banach space had the approximation property, then every Banach space would have a Schauder basis. Grothendieck thus focused the attention of functional analysts on deciding whether every Banach space have the approximation property.
Truth function Table of binary truth functions Truth-functional_logic > Table of binary truth functions In two-valued logic, there are sixteen possible truth functions, also called Boolean functions, of two inputs P and Q. Any of these functions corresponds to a truth table of a certain logical connective in classical logic, including several degenerate cases such as a function not depending on one or both of its arguments. Truth and falsehood are denoted as 1 and 0, respectively, in the following truth tables for sake of brevity.
Inverted list Applications Inverted_index > Applications With the inverted index created, the query can be resolved by jumping to the word ID (via random access) in the inverted index. In pre-computer times, concordances to important books were manually assembled. These were effectively inverted indexes with a small amount of accompanying commentary that required a tremendous amount of effort to produce.
Stevens's power law Criticisms Stevens's_power_law > Criticisms Consistent with this, Luce (1990, p. 73) observed that "by introducing contexts such as background noise in loudness judgements, the shape of the magnitude estimation functions certainly deviates sharply from a power function". Indeed, nearly all sensory judgments can be changed by the context in which a stimulus is perceived.
Enzyme Dynamics Enzyme > Mechanism > Dynamics Enzymes are not rigid, static structures; instead they have complex internal dynamic motions – that is, movements of parts of the enzyme's structure such as individual amino acid residues, groups of residues forming a protein loop or unit of secondary structure, or even an entire protein domain. These motions give rise to a conformational ensemble of slightly different structures that interconvert with one another at equilibrium. Different states within this ensemble may be associated with different aspects of an enzyme's function. For example, different conformations of the enzyme dihydrofolate reductase are associated with the substrate binding, catalysis, cofactor release, and product release steps of the catalytic cycle, consistent with catalytic resonance theory.
Luneburg method Refraction Luneburg_method > Refraction This phenomenon is called total internal reflection and allows for fiber optics technology. As light signals travel down a fiber optic cable, they undergo total internal reflection allowing for essentially no light lost over the length of the cable. It is also possible to produce polarized light rays using a combination of reflection and refraction: When a refracted ray and the reflected ray form a right angle, the reflected ray has the property of "plane polarization".
Obesity hypoventilation syndrome Diagnosis Obesity_hypoventilation_syndrome > Diagnosis If this is elevated (27 mmol/L or higher), blood gasses should be measured.To distinguish various subtypes, polysomnography is required. This usually requires brief admission to a hospital with a specialized sleep medicine department where a number of different measurements are conducted while the subject is asleep; this includes electroencephalography (electronic registration of electrical activity in the brain), electrocardiography (same for electrical activity in the heart), pulse oximetry (measurement of oxygen levels) and often other modalities. Blood tests are also recommended for the identification of hypothyroidism and polycythemia.To distinguish between OHS and various other lung diseases that can cause similar symptoms, medical imaging of the lungs (such as a chest X-ray or CT/CAT scan), spirometry, electrocardiography and echocardiography may be performed. Echo- and electrocardiography may also show strain on the right side of the heart caused by OHS, and spirometry may show a restrictive pattern related to obesity.
Brewer's yeast Differences from fission yeast Brewer's_yeast > Biology > Cell cycle > Cytokinesis > Differences from fission yeast Budding yeast form a bud from the mother cell. This bud grows during the cell cycle and detaches; fission yeast divide by forming a cell wall Cytokinesis begins at G1 for budding yeast, while cytokinesis begins at G2 for fission yeast. Fission yeast "select" the midpoint, whereas budding yeast "select" a bud site During early anaphase the actomyosin ring and septum continues to develop in budding yeast, in fission yeast during metaphase-anaphase the actomyosin ring begins to develop
Theoretical computer scientist Programming language theory and program semantics Theoretical_computer_scientist > Topics > Programming language theory and program semantics Programming language theory is a branch of computer science that deals with the design, implementation, analysis, characterization, and classification of programming languages and their individual features. It falls within the discipline of theoretical computer science, both depending on and affecting mathematics, software engineering, and linguistics. It is an active research area, with numerous dedicated academic journals.
Atomic orbitals Shapes of orbitals Atomic_orbitals > Shapes of orbitals Additionally, as is the case with the s orbitals, individual p, d, f and g orbitals with n values higher than the lowest possible value, exhibit an additional radial node structure which is reminiscent of harmonic waves of the same type, as compared with the lowest (or fundamental) mode of the wave. As with s orbitals, this phenomenon provides p, d, f, and g orbitals at the next higher possible value of n (for example, 3p orbitals vs. the fundamental 2p), an additional node in each lobe. Still higher values of n further increase the number of radial nodes, for each type of orbital.
Cell mechanics Animal Cell_mechanics > Eukaryotic > Animal Furthermore, actin filaments have the ability to be assembled and disassembled quickly, allowing them to take part in cell mobility.On the other hand, intermediate filaments are more permanent structures with a diameter of 8 to 10 nm. Composed of numerous fibrous protein strands wound together, intermediate proteins’ main role is bearing tension and retaining the shape and structure of the cell by securing the nucleus and other organelles in their designated areas. The largest cytoskeletal structure of the three types of polymers is the microtubules with a diameter of 25 nm.
Lumped parameters Newton's law of cooling Lumped_element > Thermal systems > Method > Newton's law of cooling Newton's law of cooling is an empirical relationship attributed to English physicist Sir Isaac Newton (1642–1727). This law stated in non-mathematical form is the following: The rate of heat loss of a body is proportional to the temperature difference between the body and its surroundings. Or, using symbols: An object at a different temperature from its surroundings will ultimately come to a common temperature with its surroundings. A relatively hot object cools as it warms its surroundings; a cool object is warmed by its surroundings.
Aerodynamically unstable Early aircraft Aerodynamically_unstable > Early aircraft Early attempts at heavier-than-air flight were marked by a differing concept of stability from that used today. Most aeronautical investigators regarded flight as if it were not so different from surface locomotion, except the surface was elevated. They thought of changing direction in terms of a ship's rudder, so the flying machine would remain essentially level in the air, as did an automobile or a ship at the surface. The idea of deliberately leaning, or rolling, to one side either seemed undesirable or did not enter their thinking.Some of these early investigators, including Langley, Chanute, and later Santos-Dumont and the Voisin brothers, sought the ideal of "inherent stability" in a very strong sense, believing a flying machine should be built to automatically roll to a horizontal (lateral) position after any disturbance.
Augmented learning Is augmentation really "learning"? Augmented_learning > Is augmentation really "learning"? It is proven by studies that AR can improve student understanding of complex or invisible structures. AR and VR are capable of introducing children to new concepts in fun and encouraging ways that they cannot get from a chalk board or classroom. Not only do these realities help children learn, but they also help researchers identify what specific traits aid or hinder a child’s learning capabilities.
Coronary insufficiency Acute coronary syndrome Ischaemic_heart_disease > Diagnosis > Acute coronary syndrome If there is no evidence of damage, the term "unstable angina" is used. This process usually necessitates hospital admission and close observation on a coronary care unit for possible complications (such as cardiac arrhythmias – irregularities in the heart rate). Depending on the risk assessment, stress testing or angiography may be used to identify and treat coronary artery disease in patients who have had an NSTEMI or unstable angina.
Lactate shuttle Intracellular role of the lactate shuttle Lactate_shuttle_hypothesis > Intracellular role of the lactate shuttle The lactate shuttle hypothesis also explains the balance of lactate production in the cytosol, via glycolysis or glycogenolysis, and lactate oxidation in the mitochondria (described below).
Ritz method Applications in mechanical engineering Ritz_method > Applications in mechanical engineering Consider the case whereby we want to find the resonant frequency of oscillation of a system. First, write the oscillation in the form, with an unknown mode shape Y ( x ) {\displaystyle Y(x)} . Next, find the total energy of the system, consisting of a kinetic energy term and a potential energy term.
Broadbent's filter model of attention Capacity model of attention Broadbent's_filter_model_of_attention > Attention > Capacity model of attention Daniel Kahneman took a different approach to describing attention, by describing its division, rather than selection mechanisms. He describes attention as a resource in which energy or mental effort is required. Mental effort is used while engaging in performing any mental task, and the greater the complexity, the greater the effort needed to solve a task. Kahneman believes there are three basic conditions which needed to be met for proper completion of a task.
Airy wave theory Description Airy_wave_theory > Description Surface gravity waves on a fluid are dispersive waves – exhibiting frequency dispersion – meaning that each wavenumber has its own frequency and phase speed. Note that in engineering the wave height H – the difference in elevation between crest and trough – is often used: H = 2 a and a = 1 2 H , {\displaystyle H=2a\quad {\text{and}}\quad a={\tfrac {1}{2}}H,} valid in the present case of linear periodic waves. Underneath the surface, there is a fluid motion associated with the free surface motion.
Discovery and development of gastrointestinal lipase inhibitors Drug target Discovery_and_development_of_gastrointestinal_lipase_inhibitors > Drug target Lipases in the gastrointestinal tract play a critical role in fat digestion. More than 95% of fat in food consists of triglycerides, which are categorized based on the length of fatty acids connected to glyceride backbone. The length of long-chain triglycerides prevent their absorption through the intestinal mucosa. For that reason lipases in the gastrointestinal tract must hydrolyse it to smaller molecules, free fatty acids and monoglyceride, before absorption can occur.
Magnetic moments Magnetic moment of an atom Magnetic_moments > Atoms, molecules, and elementary particles > Magnetic moment of an atom For an atom, individual electron spins are added to get a total spin, and individual orbital angular momenta are added to get a total orbital angular momentum. These two then are added using angular momentum coupling to get a total angular momentum. For an atom with no nuclear magnetic moment, the magnitude of the atomic dipole moment, m atom {\displaystyle {\mathfrak {m}}_{\text{atom}}} , is then where j is the total angular momentum quantum number, gJ is the Landé g-factor, and μB is the Bohr magneton. The component of this magnetic moment along the direction of the magnetic field is then The negative sign occurs because electrons have negative charge.
Lean startup Split testing Lean_startup > Principles > Split testing A split or A/B test is an experiment in which "different versions of a product are offered to customers at the same time." The goal of a split test is to observe differences in behavior between the two groups and to measure the impact of each version on an actionable metric. A/B testing is sometimes incorrectly performed in serial fashion, where a group of users one week may see one version of the product while the next week users see another. This undermines the statistical validity of the results, since external events may influence user behavior in one time period but not the other. For example, a split test of two ice cream flavors performed in serial during the summer and winter would see a marked decrease in demand during the winter where that decrease is mostly related to the weather and not to the flavor offer. Another way to incorrectly A/B test is to assign users to one or another A/B version of the product using any non-random method.
Caspase activation and recruitment domain IL-1 and IL-18 processing Caspase_activation_and_recruitment_domain > In the mammalian immune response > IL-1 and IL-18 processing A number of CARDs have been shown to play a role in regulating inflammation in response to bacterial and viral pathogens as well as to a variety of endogenous stress signals. Recently, studies on the NLR protein Ipaf-1 have provided insight into how CARDs participate in the immune response. Ipaf-1 features an N-terminal CARD, a nucleotide-binding domain, and C-terminal leucine-rich repeats (LRRs), thought to function in a similar fashion to those found in Toll-like receptors. The primary role of this molecule appears to be regulation of the proteolytic processing of pro-IL-1β and pro-IL-18 into their mature forms via association in a large complex known as the inflammasome. Upon activation of Ipaf-1 by the intracellular bacterium S. typhimurium or other stress signals, Ipaf-1 recruits a CARD-containing adapter termed ASC and caspase-1 in unknown stoichiometry via CARD-CARD association. This complex in turn leads to autoproteolytic activation of caspase-1 and subsequent IL-1β and IL-18 maturation.
Insect morphology Nervous system Caudal_filament > Internal > Nervous system The nervous system of an insect can be divided into a brain and a ventral nerve cord. The head capsule is made up of six fused segments, each with a pair of ganglia, or a cluster of nerve cells outside of the brain. The first three pairs of ganglia are fused into the brain, while the three following pairs are fused into a structure of three pairs of ganglia under the insect's esophagus, called the subesophageal ganglion. : 57 The thoracic segments have one ganglion on each side, which are connected into a pair, one pair per segment.
Abstraction (computer science) Considerations Data_abstraction > Considerations For instance, students in a class may be abstracted by their minimal and maximal ages; if one asks whether a certain person belongs to that class, one may simply compare that person's age with the minimal and maximal ages; if his age lies outside the range, one may safely answer that the person does not belong to the class; if it does not, one may only answer "I don't know". The level of abstraction included in a programming language can influence its overall usability. The Cognitive dimensions framework includes the concept of abstraction gradient in a formalism.
Three-way handshake Development TCP_port > Development Among this list is RFC 2581, TCP Congestion Control, one of the most important TCP-related RFCs in recent years, describes updated algorithms that avoid undue congestion. In 2001, RFC 3168 was written to describe Explicit Congestion Notification (ECN), a congestion avoidance signaling mechanism. The original TCP congestion avoidance algorithm was known as "TCP Tahoe", but many alternative algorithms have since been proposed (including TCP Reno, TCP Vegas, FAST TCP, TCP New Reno, and TCP Hybla).
Modulation Transfer Function The OTF of an ideal lens system Optical_Transfer_Function > Examples > The OTF of an ideal lens system A perfect lens system will provide a high contrast projection without shifting the periodic pattern, hence the optical transfer function is identical to the modulation transfer function. Typically the contrast will reduce gradually towards zero at a point defined by the resolution of the optics. For example, a perfect, non-aberrated, f/4 optical imaging system used, at the visible wavelength of 500 nm, would have the optical transfer function depicted in the right hand figure. It can be read from the plot that the contrast gradually reduces and reaches zero at the spatial frequency of 500 cycles per millimeter, in other words the optical resolution of the image projection is 1/500th of a millimeter, or 2 micrometer.
Lie group action Examples Quotient_manifold > Examples For every Lie group G, the following are Lie group actions: the trivial action of G on any manifold the action of G on itself by left multiplication, right multiplication or conjugation the action of any Lie subgroup H ⊆ G {\displaystyle H\subseteq G} on G by left multiplication, right multiplication or conjugationthe adjoint action of G on its Lie algebra g {\displaystyle {\mathfrak {g}}} .Other examples of Lie group actions include: the action of R {\displaystyle \mathbb {R} } on M given by the flow of any complete vector field the actions of the general linear group G L ( n , R ) {\displaystyle GL(n,\mathbb {R} )} and of its Lie subgroups G ⊆ G L ( n , R ) {\displaystyle G\subseteq GL(n,\mathbb {R} )} on R n {\displaystyle \mathbb {R} ^{n}} by matrix multiplication more generally, any Lie group representation on a vector space any Hamiltonian group action on a symplectic manifold the transitive action underlying any homogeneous space more generally, the group action underlying any principal bundle
Ice-type model Physical justification Six-vertex_model > Physical justification Several real crystals with hydrogen bonds satisfy the ice model, including ice and potassium dihydrogen phosphate KH2PO4 (KDP). Indeed, such crystals motivated the study of ice-type models. In ice, each oxygen atom is connected by a bond to four other oxygens, and each bond contains one hydrogen atom between the terminal oxygens. The hydrogen occupies one of two symmetrically located positions, neither of which is in the middle of the bond.
Malaria Vaccine RTS,S Malaria_Vaccine > Approved vaccines > RTS,S The CSP antigen causes the production of antibodies capable of preventing the invasion of hepatocytes and also elicits a cellular response enabling the destruction of infected hepatocytes. The CSP vaccine presented problems in the trial stage due to its poor immunogenicity. RTS,S attempted to avoid these by fusing the protein with a surface antigen from hepatitis B virus, creating a more potent and immunogenic vaccine.
Air handling Hot (heat A.K.A furnace) and cold (air conditioning) elements Air_handling > Components > Hot (heat A.K.A furnace) and cold (air conditioning) elements The hot water or steam is provided by a central boiler, and the chilled water is provided by a central chiller. Downstream temperature sensors are typically used to monitor and control "off coil" temperatures, in conjunction with an appropriate motorized control valve prior to the coil. If dehumidification is required, then the cooling coil is employed to over-cool so that the dew point is reached and condensation occurs.
Coronal radiative losses Processes of radiation of the solar corona Coronal_radiative_losses > Processes of radiation of the solar corona Particles are so isolated that almost all the photons can leave the Sun's surface without interacting with the matter above the photosphere: in other words, the corona is transparent to the radiation and the emission of the plasma is optically-thin. The Sun's atmosphere is not the unique example of X-ray source, since hot plasmas are present wherever in the Universe: from stellar coronae to thin galactic halos. These stellar environments are the subject of the X-ray astronomy.
Topology of compact convergence Summary Topology_of_compact_convergence In mathematics compact convergence (or uniform convergence on compact sets) is a type of convergence that generalizes the idea of uniform convergence. It is associated with the compact-open topology.
SQL syntax Null or three-valued logic (3VL) SQL_syntax > Queries > Null or three-valued logic (3VL) Consequently, these set operations in SQL may produce results not representing sure information, unlike operations involving explicit comparisons with NULL (e.g. those in a WHERE clause discussed above). In Codd's 1979 proposal (which was basically adopted by SQL92) this semantic inconsistency is rationalized by arguing that removal of duplicates in set operations happens "at a lower level of detail than equality testing in the evaluation of retrieval operations".
Medoid Medoids in high dimensions Medoid > Medoids in high dimensions Spectral clustering achieves a more appropriate analysis by reducing the dimensionality of then data using principle component analysis, projecting the data points into the lower dimensional subspace, and then running the chosen clustering algorithm as before. One thing to note, however, is that as with any dimension reduction we lose information, so it must be weighed against clustering in advanced how much reduction is necessary before too much data is lost.
Ring of Fire Earthquakes Ring_of_Fire > Very large events > Earthquakes About 90% of the world's earthquakes and 81% of the world's largest earthquakes occur along the Ring of Fire. The next most seismically active region (5–6% of earthquakes and 17% of the world's largest earthquakes) is the Alpide belt, which extends from central Indonesia to the northern Atlantic Ocean via the Himalayas and southern Europe.From 1900 to the end of 2020, most earthquakes of magnitude Mw ≥ 8.0 occurred in the Ring of Fire. They are presumed to have been megathrust earthquakes at subduction zones, including four of the most powerful earthquakes on Earth since modern seismological measuring equipment and magnitude measurement scales were introduced in the 1930s: 1960 Valdivia earthquake, Chile (magnitude Mw 9.4–9.6) 1964 Alaska earthquake, Alaska, United States (magnitude Mw 9.2) 2011 Tōhoku earthquake and tsunami, Japan (magnitude Mw 9.0–9.1) 1952 Severo-Kurilsk earthquake, Kamchatka, Russia (magnitude Mw 9.0)
Capacitive sensing Summary Capacitive_sensor In electrical engineering, capacitive sensing (sometimes capacitance sensing) is a technology, based on capacitive coupling, that can detect and measure anything that is conductive or has a dielectric constant different from air. Many types of sensors use capacitive sensing, including sensors to detect and measure proximity, pressure, position and displacement, force, humidity, fluid level, and acceleration. Human interface devices based on capacitive sensing, such as touchpads, can replace the computer mouse. Digital audio players, mobile phones, and tablet computers will sometimes use capacitive sensing touchscreens as input devices.
Lennard-Jones fluid Summary Lennard-Jones_fluid Hence, the Lennard-Jones potential describes electronically neutral atoms or molecules. The commonly used expression for the Lennard-Jones potential is where r is the distance between two interacting particles, ε is the depth of the potential well (usually referred to as 'dispersion energy'), and σ is the distance at which the particle-particle potential energy V is zero (often referred to as 'size of the particle'). The Lennard-Jones potential has its minimum at a distance of r = r m i n = 2 1 / 6 σ , {\displaystyle r=r_{\rm {min}}=2^{1/6}\sigma ,} where the potential energy has the value V = − ε .
Auditory moving-window Technical details Auditory_moving-window > Technical details This DT is the variable of interest.Analytical logicThe auditory moving-window is roughly analogous to an eye tracking task presented in the auditory modality. The eye tracking variable of interest that is thought to be closest to the DT is that of fixation duration. They are held to be directly related: a greater DT is correspondent to a greater fixation duration.
Spastic paraplegia Pathophysiology Spastic_paraplegia > Pathophysiology The major feature of HSP is a length-dependent axonal degeneration. These include the crossed and uncrossed corticospinal tracts to the legs and fasciculus gracilis. The spinocerebellar tract is involved to a lesser extent. Neuronal cell bodies of degenerating axons are preserved and there is no evidence of primary demyelination.
Computational Intelligence Summary Computer_intelligence The expression computational intelligence (CI) usually refers to the ability of a computer to learn a specific task from data or experimental observation. Even though it is commonly considered a synonym of soft computing, there is still no commonly accepted definition of computational intelligence. Generally, computational intelligence is a set of nature-inspired computational methodologies and approaches to address complex real-world problems to which mathematical or traditional modelling can be useless for a few reasons: the processes might be too complex for mathematical reasoning, it might contain some uncertainties during the process, or the process might simply be stochastic in nature. Indeed, many real-life problems cannot be translated into binary language (unique values of 0 and 1) for computers to process it.
Plasmodium falciparum Immune response Subtelomeric_regions_of_the_Plasmodium_falciparum_genome > Interaction with human immune system > Immune response The mast cells then produce signaling molecules such as TNFα and MIP-2, which activate cell eaters (professional phagocytes) such as neutrophils and macrophages.Only a small number (0.5-5%) of sporozoites enter the blood stream into the liver. In the liver, the activated CD8+ T cells from the lymph bind the sporozoites through the circumsporozoite protein (CSP). Antigen presentation by dendritic cells in the skin tissue to T cells is also a crucial process. From this stage onward the parasites produce different proteins that help in suppressing communication of the immune cells. Even at the height of the infection when red blood cells (RBCs) are ruptured, the immune signals are not strong enough to activate macrophages or natural killer cells.
Relativity theory Tests of general relativity Theory_of_Relativity > Experimental evidence > Tests of general relativity General relativity has also been confirmed many times, the classic experiments being the perihelion precession of Mercury's orbit, the deflection of light by the Sun, and the gravitational redshift of light. Other tests confirmed the equivalence principle and frame dragging.
SurE, survival protein E Function SurE,_survival_protein_E > Function The C-terminal domain is important mainly for maintaining the oligomeric state of the protein, SurE. The N-terminal domain is thought to be part of the functional domain. Since the SurE is a phosphatase enzyme it removes a phosphate group from a substance, affecting that substance's role in signal transduction.
Flood forecasting Summary Flood_forecasting However, physically-based models are state-dependent and require accurate initial conditions for optimal performance. During the so-called "warming period" of the model, the performance might be lower due to the reliance on initial conditions.
K·p perturbation theory Effective mass K.p_method > Background and derivation > Expression for a nondegenerate band > Effective mass A useful approximation for the matrix elements in direct gap semiconductors is: 2 E g m 2 ∑ m , n \| ⟨ u c , 0 \| p ℓ \| u n , 0 ⟩ \| \| ⟨ u c , 0 \| p m \| u n , 0 ⟩ \| ≈ 20 e V 1 m E g , {\displaystyle {\frac {2}{E_{g}m^{2}}}\sum _{m,\ n}{\|\langle u_{c,0}\|p_{\ell }\|u_{n,0}\rangle \|}{\|\langle u_{c,0}\|p_{m}\|u_{n,0}\rangle \|}\approx 20\mathrm {eV} {\frac {1}{mE_{g}}}\ ,} which applies within about 15% or better to most group-IV, III-V and II-VI semiconductors.In contrast to this simple approximation, in the case of valence band energy the spin–orbit interaction must be introduced (see below) and many more bands must be individually considered. The calculation is provided in Yu and Cardona. In the valence band the mobile carriers are holes. One finds there are two types of hole, named heavy and light, with anisotropic masses.
Stress force Cauchy tensor Stress_path > Cauchy tensor The components of the Cauchy stress tensor at every point in a material satisfy the equilibrium equations (Cauchy's equations of motion for zero acceleration). Moreover, the principle of conservation of angular momentum implies that the stress tensor is symmetric, that is σ 12 = σ 21 {\displaystyle \sigma _{12}=\sigma _{21}} , σ 13 = σ 31 {\displaystyle \sigma _{13}=\sigma _{31}} , and σ 23 = σ 32 {\displaystyle \sigma _{23}=\sigma _{32}} . Therefore, the stress state of the medium at any point and instant can be specified by only six independent parameters, rather than nine. These may be written where the elements σ x , σ y , σ z {\displaystyle \sigma _{x},\sigma _{y},\sigma _{z}} are called the orthogonal normal stresses (relative to the chosen coordinate system), and τ x y , τ x z , τ y z {\displaystyle \tau _{xy},\tau _{xz},\tau _{yz}} the orthogonal shear stresses.
Sheet resistance General references Surface_resistivity > References > General references Introduction to Microelectronic Fabrication (2nd ed.). New Jersey: Prentice Hall. pp.
Back annotation Inheritance Back_annotation > Hierarchy > Inheritance Another concept often used in netlists is that of inheritance. Suppose a definition of a capacitor has an associated attribute called "Capacitance", corresponding to the physical property of the same name, with a default value of "100 pF" (100 picofarads). Each instance of this capacitor might also have such an attribute, only with a different value of capacitance. And other instances might not associate any capacitance at all.
Quantum clustering Quantum Evolution, Non-Local Gradient Descent, and Tunneling Quantum_clustering > Dynamic Quantum Clustering > Quantum Evolution, Non-Local Gradient Descent, and Tunneling Whereas tuning of sigma is integral to understanding any new data set, both time step and mass can usually be left at reasonable default values and still produce useful results. An important downside of the quantum-evolution approach is that the time complexity of the evolution is now O ( n 3 ) {\displaystyle O(n^{3})} in the number of data points, since interacting with the entire potential landscape is O ( n 2 ) {\displaystyle O(n^{2})} for each point. For large data sets, the computation time would quickly become intractable. When needed, DQC addresses this problem by selecting a limited number of points from the data set to act as a basis (see next section).
Photo-multiplier tube Photoelectric effect Electrostatic_photomultiplier > History > Photoelectric effect Historically, the photoelectric effect is associated with Albert Einstein, who relied upon the phenomenon to establish the fundamental principle of quantum mechanics in 1905, an accomplishment for which Einstein received the 1921 Nobel Prize. It is worthwhile to note that Heinrich Hertz, working 18 years earlier, had not recognized that the kinetic energy of the emitted electrons is proportional to the frequency but independent of the optical intensity. This fact implied a discrete nature of light, i.e. the existence of quanta, for the first time.
Thermic fluid heater Summary Thermic_fluid_heater A thermic fluid heater is industrial heating equipment, used where only heat transfers are desired instead of pressure. In this equipment, a thermic fluid is circulated in the entire system for heat transfers to the desired processes. Combustion process heats up the thermic fluid, and this fluid carries and rejects this heat to the desired fluid for concluding the processes. After rejecting it, this fluid comes back again to the thermic fluid heater and this cycle goes on. == Referecnces ==
Kernel Patch Protection Summary Kernel_Patch_Protection Because of this, Kernel Patch Protection resulted in antivirus makers having to redesign their software without using kernel patching techniques. However, because of the design of the Windows kernel, Kernel Patch Protection cannot completely prevent kernel patching. This has led to criticism that since KPP is an imperfect defense, the problems caused to antivirus vendors outweigh the benefits because authors of malicious software will simply find ways around its defenses. Nevertheless, Kernel Patch Protection can still prevent problems of system stability, reliability, and performance caused by legitimate software patching the kernel in unsupported ways.
Deep convolutional neural network Image recognition Max_pooling > Applications > Image recognition In the ILSVRC 2014, a large-scale visual recognition challenge, almost every highly ranked team used CNN as their basic framework. The winner GoogLeNet (the foundation of DeepDream) increased the mean average precision of object detection to 0.439329, and reduced classification error to 0.06656, the best result to date. Its network applied more than 30 layers.
Propositional dynamic logic Test Propositional_dynamic_logic > Test acts as a NOP, changing nothing while allowing the action to move on. When p {\displaystyle p\,\!} is false, p ?
In situ bioremediation Hydrocarbon Degradation In_situ_bioremediation > Uses of In situ bioremediation > Hydrocarbon Degradation The metabolic mode of hydrocarbon remediation is primarily aerobic. The end products of the remediation for hydrocarbons are Carbon Dioxide and water. Hydrocarbons vary in ease of degradation based on their structure.
Crime Contagion Models Summary Crime_Contagion_Models Crime Contagion Model relates to the idea, whether crime is contagious. Contagion models predict a positive relationship between neighborhood violent crime rates and the propensity of MTO (Moving to Opportunity) participants to engage in violent crime. The notion of crime spreading across surrounding environments feeds on the idea of clinical hysteria. Hysteria and the fear of crime are the main components of the Contagion model.
Multi-configurational self-consistent field Restricted active space SCF Multi-configurational_self-consistent_field > Restricted active space SCF Since the number of CSFs quickly increases with the number of active orbitals, along with the computational cost, it may be desirable to use a smaller set of CSFs. One way to make this selection is to restrict the number of electrons in certain subspaces, done in the restricted active space SCF method (RASSCF). One could, for instance, allow only single and double excitations from some strongly occupied subset of active orbitals, or restrict the number of electrons to at most 2 in another subset of active orbitals.
Trojan wave packet Beyond single electron wave packets Trojan_wave_packet > Concepts and research > Beyond single electron wave packets The stability is maintained over a broad spectrum, and because of this, the configuration of two electron wave packets is considered to be truly nondispersive. For example, with the quantum dot helium, configured for confining electrons in two spatial dimensions, there now exists a variety of trojan wave packet configurations with two electrons, and as of 2005, only one in three dimensions. In 2012 an essential experimental step was undertaken not only generating but locking the Trojan wavepackets on adiabatically changed frequency and expanding the atoms as once predicted by Kalinski and Eberly. It will allow to create two electron Langmuir Trojan wave packets in Helium by the sequential excitation in adiabatic Stark field able to produce the circular one-electron aureola over He+ first and then put the second electron in similar state.
Inhomogeneous ordinary differential equation Lie's theory First-order_differential_equation > Theories > Lie's theory The theory has applications to both ordinary and partial differential equations.A general solution approach uses the symmetry property of differential equations, the continuous infinitesimal transformations of solutions to solutions (Lie theory). Continuous group theory, Lie algebras, and differential geometry are used to understand the structure of linear and non-linear (partial) differential equations for generating integrable equations, to find its Lax pairs, recursion operators, Bäcklund transform, and finally finding exact analytic solutions to DE. Symmetry methods have been applied to differential equations that arise in mathematics, physics, engineering, and other disciplines.
Habituation Debate about learning-status Habituation > Debate about learning-status The opposition to the considering habituation a form of learning was also based on the assumption that learning processes must produce novel behavioral responses and must occur in the cerebral cortex. Non-associative forms of learning such as habituation (and sensitization) do not produce novel (conditioned) responses but rather diminish a pre-existing (innate) responses and often are shown to depend on peripheral (non-cerebral) synaptic changes in the sensory-motor pathway. Most modern learning theorists, however, consider any behavioral change that occurs as a result of experience to be learning, so long as it cannot be accounted for by motor fatigue, sensory adaptation, developmental changes or damage.
Mitochondrial genes Genetic illness Mitochondrial_genes > Mutations and disease > Genetic illness Mutations of mitochondrial DNA can lead to a number of illnesses including exercise intolerance and Kearns–Sayre syndrome (KSS), which causes a person to lose full function of heart, eye, and muscle movements. Some evidence suggests that they might be major contributors to the aging process and age-associated pathologies. Particularly in the context of disease, the proportion of mutant mtDNA molecules in a cell is termed heteroplasmy. The within-cell and between-cell distributions of heteroplasmy dictate the onset and severity of disease and are influenced by complicated stochastic processes within the cell and during development.Mutations in mitochondrial tRNAs can be responsible for severe diseases like the MELAS and MERRF syndromes.Mutations in nuclear genes that encode proteins that mitochondria use can also contribute to mitochondrial diseases. These diseases do not follow mitochondrial inheritance patterns, but instead follow Mendelian inheritance patterns.
Microfilament protein Cell movement G_actin > Function > Cell movement Actin is also involved in cell movement. A meshwork of actin filaments marks the forward edge of a moving cell, and the polymerization of new actin filaments pushes the cell membrane forward in protrusions called lamellipodia. These membrane protrusions then attach to the substrate, forming structures known as focal adhesions that connect to the actin network. Once attached, the rear of the cell body contracts squeezing its contents forward past the adhesion point. Once the adhesion point has moved to the rear of the cell, the cell disassembles it, allowing the rear of the cell to move forward.
Recurrent evolution Summary Recurrent_evolution These patterns are of particular interest to evolutionary biologists, as they can demonstrate the underlying forces governing evolution. Recurrent evolution is a broad term, but it is usually used to describe recurring regimes of selection within or across lineages. While most commonly used to describe recurring patterns of selection, it can also be used to describe recurring patterns of mutation; for example, transitions are more common than transversions. The concept encompasses both convergent evolution and parallel evolution; it can be used to describe the observation of similar repeating changes through directional selection as well as the observation of highly conserved phenotypes or genotypes across lineages through continuous purifying selection over large periods of evolutionary time.
KTHNY theory Renormalization of elasticity KTHNY_theory > Main idea > Renormalization of elasticity If additional (virtual) dislocations are present, the crystal will get additionally softer. If the crystal is additionally softer, the fugacity will increase further... and so on and so forth. David Nelson, Bertrand Halperin and independently Peter Young formulated this in a mathematically precise way, using renormalization group theory for the fugacity and the elasticity: In the vicinity of the continuous phase transition, the system becomes critical – this means that it becomes self-similar on all length scales ≫ a {\displaystyle \gg a} .
Write once, compile anywhere Development of high-level programming languages Write_once,_compile_anywhere > Development of high-level programming languages To combat these problems, various high-level languages were developed that were usable for general purpose application program development, but could be used to provide reports and information for people with specialized requirements. These include: BASIC, a simplified programming language which could be used to build "real world" complex applications, as well as simple programs to solve a problem, and was very accessible for amateur programmers. Its ease of use made BASIC well suited as an introductory computer programming class in many colleges. C, a general-purpose programming language often suitable for writing programs which would otherwise require assembly language.
Tree puzzle Summary Tree-Puzzle TREE-PUZZLE is a computer program used to construct phylogenetic trees from sequence data by maximum likelihood analysis. Branch lengths can be calculated with and without the molecular clock hypothesis. The software also implemented likelihood mapping, a method to visualize phylogenetic information in datasets, as well as several tests to assess if the likelihoods of trees are significantly worse than those of other trees. The program's successor is IQ-TREE.
For (command) Script syntax For_loop > Timeline of the for-loop syntax in various programming languages > 1995: CFML > Script syntax Simple index loop: Using an array: Using a list of string values: The above list example is only available in the dialect of CFML used by Lucee and Railo.
Matrix protocol Summary Matrix_protocol Matrix (sometimes stylized as ) is an open standard and communication protocol for real-time communication. It aims to make real-time communication work seamlessly between different service providers, in the way that standard Simple Mail Transfer Protocol email currently does for store-and-forward email service, by allowing users with accounts at one communications service provider to communicate with users of a different service provider via online chat, voice over IP, and videotelephony. It therefore serves a similar purpose to protocols like XMPP, but is not based on any existing communication protocol.
Bonding in solids Molecular to network covalent Bonding_in_solids > Solids of intermediate kinds > Molecular to network covalent Materials can be intermediate between molecular and network covalent solids either because of the intermediate organization of their covalent bonds, or because the bonds themselves are of an intermediate kind. Intermediate organization of covalent bonds: Regarding the organization of covalent bonds, recall that classic molecular solids, as stated above, consist of small, non-polar covalent molecules. The example given, paraffin wax, is a member of a family of hydrocarbon molecules of differing chain lengths, with high-density polyethylene at the long-chain end of the series. High-density polyethylene can be a strong material: when the hydrocarbon chains are well aligned, the resulting fibers rival the strength of steel.
Connected graph Components and cuts 4-connected_graph > Components and cuts A vertex cut or separating set of a connected graph G is a set of vertices whose removal renders G disconnected. The vertex connectivity κ(G) (where G is not a complete graph) is the size of a minimal vertex cut. A graph is called k-vertex-connected or k-connected if its vertex connectivity is k or greater.
Turing-computable function Alan Turing's a-machine Universal_computer > History > Alan Turing's a-machine The development of these ideas leads to the author's definition of a computable function, and to an identification of computability with effective calculability. It is not difficult, though somewhat laborious, to prove that these three definitions are equivalent. Alan Turing invented the "a-machine" (automatic machine) in 1936.
Serotonin toxicity Causes Serotonin_toxicity > Causes It can take at least four weeks for this enzyme to be replaced by the body in the instance of irreversible inhibitors. With respect to tricyclic antidepressants, only clomipramine and imipramine have a risk of causing SS.Many medications may have been incorrectly thought to cause SS. For example, some case reports have implicated atypical antipsychotics in SS, but it appears based on their pharmacology that they are unlikely to cause the syndrome.
Stack register Stack registers in x86 Stack_pointer > Stack registers in x86 Usually, the running program pushes registers to the stack to make use of the registers for other purposes, like to call a routine that may change the current values of registers. To restore the values stored at the stack, the program shall contain machine instructions like this: POP BX copies the word at 0x1F81C (which is the old value of BX) to BX, then increases SP by 2. SP now is 0xF81E. POP AX copies the word at 0x1F81E to AX, then sets SP to 0xF820.
Trend estimation Data as trend plus noise Linear_trend_estimation > Data as trend plus noise From the above discussion of trends in random data with known variance, we know the distribution of calculated trends to be expected from random (trendless) data. If the estimated trend, a ^ {\displaystyle {\hat {a}}} , is larger than the critical value for a certain significance level, then the estimated trend is deemed significantly different from zero at that significance level, and the null hypothesis of zero underlying trend is rejected. The use of a linear trend line has been the subject of criticism, leading to a search for alternative approaches to avoid its use in model estimation.
Allergic response Mechanism Allergic_response > Mechanism Allergies are an abnormal immune reaction. The human immune system is designed to protect the body from potential harm and in people who have allergies the immune system will react to allergens (substances that trigger an immune response). The immune system will produce immunoglobulin E, IgE, antibodies for each allergen. The antibodies will cause cells in the body to produce histamine.
Homeodomain proteins Regulation Homeodomain_fold > Regulation Hox genes and their associated microRNAs are highly conserved developmental master regulators with tight tissue-specific, spatiotemporal control. These genes are known to be dysregulated in several cancers and are often controlled by DNA methylation. The regulation of Hox genes is highly complex and involves reciprocal interactions, mostly inhibitory. Drosophila is known to use the polycomb and trithorax complexes to maintain the expression of Hox genes after the down-regulation of the pair-rule and gap genes that occurs during larval development. Polycomb-group proteins can silence the Hox genes by modulation of chromatin structure.
Rigid body kinetics Force-torque equations Rigid_body_kinetics > Rigid body in three dimensions > Force-torque equations Using the center of mass and inertia matrix, the force and torque equations for a single rigid body take the form and are known as Newton's second law of motion for a rigid body. The dynamics of an interconnected system of rigid bodies, Bi, j = 1, ..., M, is formulated by isolating each rigid body and introducing the interaction forces. The resultant of the external and interaction forces on each body, yields the force-torque equations Newton's formulation yields 6M equations that define the dynamics of a system of M rigid bodies.
Gödel's constructible universe Relative constructibility Set-theoretic_constructibility > Relative constructibility Otherwise, the axiom of choice will fail in L ( A ) {\displaystyle L(A)} . A common example is L ( R ) {\displaystyle L(\mathbb {R} )} , the smallest model that contains all the real numbers, which is used extensively in modern descriptive set theory. The class L {\displaystyle L} is the class of sets whose construction is influenced by A {\displaystyle A} , where A {\displaystyle A} may be a (presumably non-constructible) set or a proper class.
Comparison of object–relational database management systems Summary Comparison_of_object–relational_database_management_systems This is a comparison of object–relational database management systems (ORDBMSs). Each system has at least some features of an object–relational database; they vary widely in their completeness and the approaches taken. The following tables compare general and technical information; please see the individual products' articles for further information. Unless otherwise specified in footnotes, comparisons are based on the stable versions without any add-ons, extensions or external programs.
Johann Bernoulli Works Johann_Bernoulli > Works Recherches physiques et géométriques sur la question comment se fait la propagation de la lumière (in French). Paris. Imprimerie Royale.
Eigencurve Summary Eigencurve In number theory, an eigencurve is a rigid analytic curve that parametrizes certain p-adic families of modular forms, and an eigenvariety is a higher-dimensional generalization of this. Eigencurves were introduced by Coleman and Mazur (1998), and the term "eigenvariety" seems to have been introduced around 2001 by Kevin Buzzard (2007).
Self oscillation History of the subject Self-exciting_oscillation > History of the subject The study of self-oscillators dates back to Robert Willis, George Biddell Airy, James Clerk Maxwell, and Lord Rayleigh in the 19th century. The term itself (also translated as "auto-oscillation") was coined by the Soviet physicist Aleksandr Andronov, who studied them in the context of the mathematical theory of the structural stability of dynamical systems. Other important work on the subject, both theoretical and experimental, was due to André Blondel, Balthasar van der Pol, Alfred-Marie Liénard, and Philippe Le Corbeiller in the 20th century.The same phenomenon is sometimes labelled as "maintained", "sustained", "self-exciting", "self-induced", "spontaneous", or "autonomous" oscillation. Unwanted self-oscillations are known in the mechanical engineering literature as hunting, and in electronics as parasitic oscillations. Important early studied examples of self-oscillation include the centrifugal governor and railroad wheels.
Alain Badiou Mathematics as ontology Alain_Badiou > Being and Event > Mathematics as ontology When these things appear in Badiou's texts it is always allusively, with fragments of symbolism detached from the context that endows them with sense, and often with free variables and bound variables colliding randomly. No proof is clearly stated or examined, and the jargon of set theory is waved like a magician's wand, to give authority to bursts of all but unintelligible metaphysics.An example of a critique from a mathematician's point of view is the essay 'Badiou's Number: A Critique of Mathematics as Ontology' by Ricardo L. Nirenberg and David Nirenberg, which takes issue in particular with Badiou's matheme of the Event in Being and Event, which has already been alluded to in respect of the 'axiom of foundation' above. Nirenberg and Nirenberg write: Rather than being defined in terms of objects previously defined, ex is here defined in terms of itself; you must already have it in order to define it. Set theorists call this a not-well-founded set. This kind of set never appears in mathematics – not least because it produces an unmathematical mise-en-abîme: if we replace ex inside the bracket by its expression as a bracket, we can go on doing this forever – and so can hardly be called "a matheme."'
Ancient languages Summary Ancient_languages An ancient language is any language originating in times that may be referred to as ancient. There are no formal criteria for deeming a language ancient, but a traditional convention is to demarcate as "ancient" those languages that existed prior to the 5th century. Linguist Roger Woodward has said that "erhaps, then, what makes an ancient language different is our awareness that it has outlived those for whom it was an intimate element of the psyche".By this definition, the term includes languages attested from ancient times in the list of languages by first written accounts, and described in historical linguistics, and particularly the languages of classical antiquity, such as Chinese being the oldest language till date, Tamil, Ancient Greek, Hebrew, Old Persian, Avestan, Sanskrit, Latin, Arabic, Kannada and Telugu. The term may also encompass other classical languages and various extinct languages.
Marine habitat Overview Marine_environment > Overview The presence of seawater is common to all marine habitats. Beyond that many other things determine whether a marine area makes a good habitat and the type of habitat it makes. For example: temperature – is affected by geographical latitude, ocean currents, weather, the discharge of rivers, and by the presence of hydrothermal vents or cold seeps sunlight – photosynthetic processes depend on how deep and turbid the water is nutrients – are transported by ocean currents to different marine habitats from land runoff, or by upwellings from the deep sea, or they sink through the sea as marine snow salinity – varies, particularly in estuaries or near river deltas, or by hydrothermal vents dissolved gases – oxygen levels in particular, can be increased by wave actions and decreased during algal blooms acidity – this is partly to do with dissolved gases above, since the acidity of the ocean is largely controlled by how much carbon dioxide is in the water.
Glossary of civil engineering K Glossary_of_civil_engineering > K Kalman filter kelvin kinematics Kirchhoff's circuit laws Kirchhoff's equations
History of scientific method Ibn al-Haytham History_of_scientific_method > Emergence of inductive experimental method > Ibn al-Haytham He also demonstrated the conjecture by placing a straight stick or a taut thread next to the light beam.Ibn al-Haytham also employed scientific skepticism and emphasized the role of empiricism. He also explained the role of induction in syllogism, and criticized Aristotle for his lack of contribution to the method of induction, which Ibn al-Haytham regarded as superior to syllogism, and he considered induction to be the basic requirement for true scientific research.Something like Occam's razor is also present in the Book of Optics. For example, after demonstrating that light is generated by luminous objects and emitted or reflected into the eyes, he states that therefore "the extramission of rays is superfluous and useless."

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