Spectroscopy

Table of contents1 Historical overview2 Absorption theory Spectroscopy is a powerful method of investigation of the structure of matter that is based on the analysis of the decomposition of light emitted by it in its fundamental wavelengths. The measurement and analysis (by means of a spectrometer) of a spectrum is called spectroscopy; it is the study of …

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Fluid statics [hydrostatics]

Fluid statics (or hydrostatics) is a branch of fluid mechanics that studies fluids at rest, i.e., any continuous body for which Pascal’s law is valid with constant average velocity in time and vectorially homogeneous in space. In particular, hydrostatics is that part of hydraulics that considers water in equilibrium, that is, not presenting reciprocal displacements …

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Fluid dynamics [fluid flow]

In physics, fluid dynamics is a branch of fluid mechanics that studies the behavior of fluids (i.e., liquids and gases) in motion, as opposed to fluid statics; solving a fluid dynamic problem generally involves solving (analytically or numerically) complex differential equations to calculate various properties of the fluid including velocity, pressure, density, or temperature, as …

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Deduction

Table of contents1 History of deductive method1.1 From the Middle Ages to the Modern Age1.2 Karl Popper Deduction is defined as reasoning by which logically necessary conclusions are derived from certain premises; truth or judgment arrived at by this process | in com. usage, the act of inferring, of arguing; what is inferred, inferred: arbitrary …

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Reason

Table of contents1 Etymology and related words2 Philosophy3 Jurisprudence4 Economics5 Logical reasoning methods and argumentation5.1 Deductive reasoning5.2 Inductive reasoning5.3 Analogical reasoning5.4 Abductive reasoning5.5 Fallacious reasoning The reason is the capacity of consciously making sense of things, judgments, applying logic, and adapting or justifying practices, institutions, and beliefs based on new or existing information. It is closely associated …

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Apple cider vinegar

Table of contents1 Nutritional Properties2 Possible benefits and contraindications Apple cider vinegar is the product of the fermentation of cider or apple juice and it is used as a condiment, also because of its aroma. The presence of apples makes it a condiment rich in many beneficial properties. It has a deep yellow color and …

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Friction

Table of contents1 Friction coefficient2 Types of friction3 Static friction4 Kinetic friction5 The dynamic manifestation of friction6 Sliding friction7 Forms sliding friction8 Influence of speed9 Influence of pressure10 Fluidostatic effect of pressure11 Effect of molecular actions12 Rolling friction13 Laws of the rolling friction of Charles-Augustin de Coulomb14 History of friction Friction can be defined as the …

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Liquid

Table of contents1 Properties of liquids2 Ionic liquid2.1 Properties of ionic liquids3 Magnetic liquid In liquids, the atoms or molecules are not as tightly bound as in solids, and due to that, they have some freedom to move around. The liquid state is a condensed state of matter, because even in it, as in solids, the …

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Solubility

Solubility is the property of a solid, liquid, or a gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent. It is usually expressed in grams per 100 g of solvent at a specified temperature. According to the IUPAC definition, solubility is the analytical composition of a saturated solution expressed as a proportion of a …

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Superfluid [superfluidity]

Table of contents1 Superfluid applications2 Superfluidity3 Phenomenology of 4He Superfluids have many unusual properties. They behave like typical components of solutions, with all the properties associated with normal fluid and superfluid components. Therefore it is impossible to set a temperature gradient in a superfluid, as it is impossible to set a potential difference in a …

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Electricity

Table of contents1 Historical notes: from the classical age to the XVII century2 Historical notes: the XIX century Electricity generically indicates all physical phenomena on macroscopic scale that involve one of the fundamental interactions, electromagnetic interaction, with particular reference to electrostatics. At microscopic level, these phenomena are related to the interaction between charged particles at …

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Electrodynamics

Table of contents1 Classical electrodynamics2 Quantum electrodynamics Electrodynamics is a branch of electromagnetism that studies the reciprocal actions between circuits traversed by current or electric charges in motion and the magnetic fields generated (time-varying electromagnetic fields) by such sources. Generally with this term we commonly refer to classical electrodynamics; the quantum or photonic-corpuscular approach to …

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Thermosetting polymer

Thermosetting polymers (or thermosetting resins) belong to the group of plastic materials; they are particular polymers that, after an initial softening phase due to heating, harden due to the effect of three-dimensional cross-linking; during the softening phase due to the combined effect of heat and pressure they are deformable and once hardened they are very …

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Thermoplastic

Table of contents1 Amorphous thermoplastic polymers2 Crystalline thermoplastic polymers3 Morphology of thermoplastic polymers Thermoplastics (or thermoplastic polymers or thermoplastic resins) are those plastic materials that acquire malleability, that is, they soften under the action of heat. At this stage they can be molded or formed into finished objects and then by cooling they become rigid …

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plastic

Plastic

Table of contents1 Characteristics and technological properties of plastics2 Classification of plastics3 Plastics production and processing techniques4 History of plastics Plastic is an organic material consisting of a wide range of synthetic or semi-synthetic organic compounds, mainly from pure polymers or blended (high molecular weight) with additives. Its malleability allows solid objects of any shape …

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Poly[methyl methacrylate]

Polymethyl methacrylate (PMMA) is a plastic material formed from polymers of methyl methacrylate, the methyl ester of methacrylic acid. It is a thermoplastic polymer. It is also known by the trade names of Plexiglas, Perspex, Amanite, Lucite, Trespex, Vitroflex, Acrivill, Perclax, Limacryl, Crylux, Oroglas, Setacryl, Altuglas. It is a thermoplastic substance obtained by polymerization of …

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Aberration

Defocus aberration. Chromatic aberration. Comatic aberration (or coma). Petzval field curvature. Spherical aberration. Aberration of starlight.

Metrology

Metrology is the science that has as its purpose the identification of the most suitable and precise methods to carry out the measurement of any physical quantity, of which it also defines the unit of measurement, and to express and use in a correct way the result of the measurement itself. It therefore deals only …

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Space

Space is the undefined and unbounded entity that contains all material things. These, having an extension, occupy a part of it and assume a position in space, which is defined quantitatively according to the principles of geometry, and qualitatively, according to relationships of proximity (distance) and size (smallness). Real physical space is believed to be …

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Kinematics

Kinematics (from the French term cinématique, coined by the physicist André-Marie Ampère from the greek κίνημα -ατος, kinema -atos = “movement”, derived in turn from the verb κινέω, kineo = “to move”) is that branch of Newtonian mechanics that deals with quantitatively describing the motion of bodies, using only the notions of space and time, …

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Ballistics

Table of contents1 History of ballistics2 Ballistics branches2.1 Internal ballistics2.2 External ballistics2.3 Terminal ballistics2.4 Forensic ballistics Ballistics is the branch of mechanical physics that studies the motion of a projectile, understood as an inert body subjected to the force of gravity and the viscous friction of the physical medium of propagation. The projectile has an …

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Antimatter

In contrast to ordinary matter we talk about antimatter, that is the particular matter made of antiparticles, in which instead of each single fundamental particle is replaced by the particle that is obtained from it by charge conjugation. In other words, antimatter is the matter consisting of antiparticles, corresponding in mass to the particles of …

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Dark energy

Dark energy is a form of energy that exerts a negative, repulsive pressure, behaving like the opposite of gravity. It has been hypothesised to account for the observational properties of distant type Ia supernovae, which show the universe going through an accelerated period of expansion. Like dark matter, dark energy is not directly observed, but …

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Gravitational lens

Table of contents1 Theoretical origin and first observations2 Specific uses of gravitational lenses3 Gravitational microlensing4 References In astronomy, a gravitational lens is a distribution of matter, such as a galaxy or black hole, capable of curving the trajectory of transiting light in a manner analogous to an optical lens. Gravitational lenses are predicted by the …

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Dark matter

Dark matter, in cosmology, indicates a hypothetical component of matter that, unlike known matter, would emit electromagnetic radiation and would currently be detectable only indirectly through its gravitational effects. The hypothesis was born to justify experimental observations according to which, in relation to the laws of gravitation, dark matter would constitute 90% of the mass …

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Crystal

In mineralogy and crystallography, a crystal (from the greek κρύσταλλος, krýstallos, ice) is defined as the atomic or molecular structure that matter in the solid state presents, chemically and physically homogeneous. In other words atoms, molecules or ions have a regular three-dimensional geometric arrangement, which is repeated indefinitely in the three spatial dimensions, called crystal …

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Solid-state chemistry

Solid-state chemistry, also sometimes referred as materials chemistry, is the study of the synthesis, structure, and properties of solid phase materials, particularly, but not necessarily exclusively of, non-molecular solids. Historically, the origin of solid state chemistry can be traced back to the use of experimental techniques for the characterization of minerals, and therefore to the …

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Solid

Table of contents1 Categories and classification of solids2 Crystalline solids2.1 Characteristics of crystalline solids2.2 Determination of the dynamic behavior of free electrons in the crystal lattice2.3 Electron distribution in a band according to fermi-dirac statistics3 Ionic solids4 Molecular solids5 Covalent network solids6 Metallic solids7 Amorphous solids7.1 Characteristics of amorphous solids8 Physical properties of solids8.1 Mechanical8.2 …

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Solid-state physics

A particularly important role in the development of modern technology is played by solid-state physics, which studies the properties of solids in relation to their intimate structure both from the crystallographic point of view (type of elementary cell, lattice parameters, position in the cell of atoms of different species), and with regard to the forces …

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Olmecs

The mother of Mesoamerican cultures was the Olmec civilization. The Olmec civilization flourished during the Mesoamerican (pre-classical) formative period, extending approximately from 1500 BCE to 400 BCE. The Olmecs constituted the first Mesoamerican civilization and established the foundations of later cultures. The Olmec produced several major works of art, architecture, pottery, and sculpture. Most recognizable are their giant head …

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How to solve series #1

Table of contents1 Exercise 1.02 Exercise 1.13 Exercise 1.34 Exercise 1.45 Exercise 1.56 Exercise 1.67 Exercise 1.78 Exercise 1.8 Verify that the following series converges. Exercise 1.0 \(\displaystyle{\sum_{n=1}^{\infty}}\dfrac{2}{n^2+2n}\) \(\dfrac{2}{n^2+2n}=\dfrac{2}{n(n+2)}=\dfrac{1}{n}-\dfrac{1}{n+2}\) \(S_1=a_1=1-\dfrac{1}{3}\) \(S_2=a_1+a_2=\left(1-\dfrac{1}{3}\right)+\left(\dfrac{1}{2}-\dfrac{1}{4}\right)=1+\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{1}{4}\) \(S_3=a_1+a_2+a_3=\left(1-\dfrac{1}{3}\right)+\left(\dfrac{1}{2}-\dfrac{1}{4}\right)+\left(\dfrac{1}{3}-\dfrac{1}{5}\right)=1+\dfrac{1}{2}-\dfrac{1}{4}-\dfrac{1}{5}\) \(S_4=a_1+a_2+a_3+a_4=\left(1-\dfrac{1}{3}\right)+\left(\dfrac{1}{2}-\dfrac{1}{4}\right)+\left(\dfrac{1}{3}-\dfrac{1}{5}\right)+\left(\dfrac{1}{4}-\dfrac{1}{6}\right)=1+\dfrac{1}{2}-\dfrac{1}{5}-\dfrac{1}{6}\) \(S_n=a_1+a_2+…+a_n=1+\dfrac{1}{2}-\dfrac{1}{n+1}-\dfrac{1}{n+2}\) \(\displaystyle{\lim_{n\rightarrow\infty}}S_n=1+\dfrac{1}{2}=\dfrac{3}{2}\) the series converge and the sum is: \(\dfrac{3}{2}\) Exercise 1.1 \(\displaystyle{\sum_{n=1}^{\infty}}\dfrac{\sqrt{n+1}-\sqrt{n}}{\sqrt{n^2+n}}\) \(a_n=\dfrac{\sqrt{n+1}-\sqrt{n}}{\sqrt{n^2+n}}=\dfrac{\sqrt{n+1}}{\sqrt{n}\sqrt{n+1}}-\dfrac{\sqrt{n}}{\sqrt{n}\sqrt{n+1}}=\dfrac{1}{\sqrt{n}}-\dfrac{1}{\sqrt{n+1}}\) \(S_1=a_1=1-\dfrac{1}{\sqrt{2}}\) \(S_2=a_1+a_2=\left(1-\dfrac{1}{\sqrt{2}}\right)+\left(\dfrac{1}{\sqrt{2}}-\dfrac{1}{\sqrt{3}}\right)=1+\dfrac{1}{\sqrt{3}}\) \(S_3=a_1+a_2+a_3=\left(1-\dfrac{1}{\sqrt{2}}\right)+\left(\dfrac{1}{\sqrt{2}}-\dfrac{1}{\sqrt{3}}\right)+\left(\dfrac{1}{\sqrt{3}}-\dfrac{1}{\sqrt{4}}\right)=1+\dfrac{1}{\sqrt{4}}\) \(S_n=a_1+a_2+…+a_n=1-\dfrac{1}{\sqrt{n}}\) the series converge and …

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Time

Table of contents1 Notion of time2 Cosmic time3 Relativistic time4 Thermodynamic time5 Time in philosophy6 Time in business economics Time is an abstract entity (as well as a physical quantity), useful for quantifying and measuring the flow of events. Any measurement of time involves measuring a change in some physical quantity, hence: time is the …

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Goods

Table of contents1 Public goods2 Giffen goods3 Veblen goods In economics, goods are items that are usually (but not always) tangible, that satisfy human wants and provide utility. Goods consist of material objects, even complex ones, which are considered differently from non-material goods, that is, from services. The goods can be an economic, natural or technically produced …

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Microeconomics

Table of contents1 Basic concepts of microeconomics2 Use and limits of microeconomic theory Microeconomics is a branch of economics that studies the behavior of individual economic agents, or systems with a limited number of agents, in making decisions regarding the allocation of scarce resources and the interactions among these individuals and firms. The microeconomic perspective focuses on parts …

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Political economy

Table of contents1 History of economic thought2 From the origins to the welfare state3 The crisis and the reform of the welfare state Political economy studies the activity carried out by men in order to use in the most efficient way the available resources in order to satisfy their needs. Since resources are limited and …

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Totipotency

Totipotency, is the ability of a single stem cell to give rise to all the different cell types in an organism. In other words, it is the ability of a single cell to divide and produce all the differentiated cells of an organism. This capacity is peculiar to embryonic stem cells up to a certain …

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Macroeconomics

Macroeconomics is a branch of economics that deals with the performance, structure, behavior, and decision making of an economy as a whole. This includes regional, national, and global economies. The macroeconomic perspective looks at the economy as a whole, focusing on objectives such as growth in living standards, unemployment, and inflation. Macroeconomics has two types …

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Sketch [croquis]

Sketch represents the preparatory study of a small-scale model of a work of art (e.g., a painting, sculpture, fresco, monument, or architectural work) before it is finally executed. The sketch is a well-defined preparatory study, but it is distinguished by the use of color; it is in fact executed in tempera or oil on supports …

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Antibonding molecular orbital

An antibonding molecular orbital is a type of chemical bond given by the overlap of two half-full molecular orbitals. This kind of bond weakens the chemical bond between two atoms and helps to raise the energy of the molecule relative to the separated atoms. Such an orbital has one or more nodes in the bonding region between …

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Kinematic chain

When the kinematic pairs are coupled in such a way that the last link is joined to the first link to transmit definite motion (i.e. completely or successfully constrained motion), it is called a kinematic chain. The degrees of freedom, or mobility, of a kinematic chain is the number of parameters that define the configuration of …

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Kinematic link

A kinematic link is defined as the part of the machine which has a relative motion with respect to some other part of the same machine is called kinematic link or element. Kinematic links can be divided into four types: Rigid link: in this type of link that does not undergo any deformation while transmitting motion. Links, …

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Range of interval (or span)

In metrology, the range of the interval \([a, b]\) is the difference \((b-a)\) and is denoted by \(r[a, b]\). It also represents a static characteristic of an instrument. It defines the maximum and minimum values of the inputs or the outputs for which the instrument is recommended to use. For example, for a temperature measuring instrument the …

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Chinese philosophy

Table of contents1 Cosmological reflection2 The doctrine of knowledge Towards the end of the 19th century, the expression zhexue, borrowed from the Japanese language, was adopted in China to convey the term philosophy; an expression which literally means «knowledge to become a wise person» and which, in the Confucian perspective, should be understood as the …

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Arabic philosophy

Table of contents1 Arab-Christian philosophy2 Arab-Islamic philosophy One can speak of Arabic philosophy with regard to historical phenomena that occurred in different cultural and religious spheres, which also differed according to the historical period and the geographical area in which they were located, but which are basically united by the use of the same language: …

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Jewish philosophy

Table of contents1 Connections to Greek and Arabic philosophies2 Jewish Aristotelianism3 Jewish enlightenment We define as Jewish philosophy the philosophical ideas of those authors who lived in various geographical regions (in the Near and Middle East, in Europe and northern Africa) after the 1st century AD, who used different languages as a means of expression …

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Practical philosophy

This is a branch of philosophical sciences whose origins lay on the distinction theorized by Socrates and the Sophists and clarified in Plato, who generally divides science into πρακτική (referring to πρᾶξις, action), and γνωστική (referring to γνῶσις, knowledge), and more fully in Aristotle, who adds the poetic (ποιητική, referring to ποίησις, productive action) to …

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Analytic philosophy

Table of contents1 From the school of G.E. Moore to the Tractatus of L. Wittgenstein2 New hypotheses of language analysis Current of thought developed mainly in England from the beginning of the 20th century, and aimed mainly at the study of language in its various aspects (scientific, daily, ethical, logical, etc.), favoring the analysis of …

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Christian philosophy

Christian philosophy is also interwoven with religious and theological themes: it can’t indeed separate itself from the so-called “revealed truths,” and therefore from the faith, and it has its true subject in God, within whom exclusively the world and the self can be understood, as the creature is understood in the creator, the finite in …

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Tibetan philosophy

Tibetan philosophy developed from the texts and assumptions of Indian Buddhism and almost exclusively in the Buddhist sphere, offering interesting solutions and developments to the Madhyamaka, Pramāṇavāda and, to a lesser extent, Yogācāra currents. Some key concepts used by contemporary interpreters of Indian and Buddhist philosophy, such as the distinction between a *svātantrika and a …

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Modern philosophy

In Francis Bacon, we find, as in the whole Renaissance, the ideal of the regnum hominis, of the rational domination of nature, which is the purpose of knowledge and also of the practical organization of knowledge. Bacon offers an encyclopedia of the different forms of knowledge, an organic arrangement of the different sciences. We have …

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Philosophy

Table of contents1 The search for the principle of things2 Philosophy as “first science”3 Philosophy as the practice of wisdom4 Humanism and Renaissance5 From existentialism to hermeneutics6 Philosophy as clarification and analysis7 The current debate8 Related keywords Philosophy can be defined as a form of knowledge that, despite the wide variety of its expressions, exhibits …

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Electric current

Ampere (unit of electric current). Direct current (DC). Alternating current (AC). Overcurrent.

Stability

Table of contents1 Definitions2 Metrology2.1 Reading stability of a measurement2.2 Measurement stability over time2.3 Stability of measuring instrumentation2.4 Zero stability3 Construction engineering4 Meteorology5 Aeronautics6 Navy The word stability [from Middle English stabletee; stabilite, from Old French stabilité; from Latin root of stabilitas (“firmness, steadfastness”), from stabilis (“steadfast, firm”)] has several meanings based on context and …

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Drift

In metrology, drift can be defined as the variation caused in the output of an instrument, which is not caused by any change in the input. Drift in a measuring instrument is mainly caused by internal temperature variations and lack of component stability. It also represents a static characteristic of an instrument. A change in the zero output of …

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Threshold (dead space)

In Metrology, dead space or threshold is a static characteristic of an instrument defined as the range of different input values over which there is no change in output value. If the instrument input is increased very gradually from zero there will be some minimum value below which no output change can be detected. This minimum value defines the …

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Emotion

Table of contents1 The components of emotion2 What is not an emotion?3 Functions and theories of emotions4 Types of emotions Emotions (from Latin emotio, meaning “movement”, “impulse”) are a multi-componential process, articulated in several components: mental and physiological states associated with psychological changes, internal or external stimuli, natural or learned. They represent an inner process …

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marius masalar music

Music

Table of contents1 History of Music1.1 Music in ancient Egypt1.2 Music of Mesopotamia1.3 Music in ancient Greece1.4 Medieval music1.5 New genres and forms1.6 Towards Romanticism1.7 Germany, Italy and France1.8 Outside Europe1.9 The 20th century: up to the fifties1.10 The 20th century: from the sixties to the eighties1.11 The 20th century: the nineties1.12 The 20th century: …

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Measuring lag

The delay in the response of a measuring instrument to a change in the measured quantity is known as measuring lag. Thus it is the retardation delay in the response of a measurement system to changes in the measured quantity. This lag is usually quite small, but this small lag becomes highly important when high-speed measurements …

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Pointillisme [pointillism]

Pointillisme (pointillism) was a pictorial current that emerged around 1885, baptized Neo-Impressionism by the critic F. Fénéon in 1886, the year in which G. Seurat presented La Grande-Jatte (Chicago, Art Institute) at the Salon des Indépendants. An article entitled Neo-Impressionism, in which the technical procedures and aesthetics of the movement were exposed, was also published …

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Romanticism

Table of contents1 1770-18002 1800-18243 1824-1840 The difficulty encountered in finding a definition for Romanticism that encompasses both its complex development and regional particularities seems insurmountable. Romanticism can be understood primarily as the acceptance and, finally, the exaltation of those elements that are characteristic of human consciousness and behavior: melancholy, irrationality, doubt, individual eccentricity, excessive …

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Macchiaioli

Table of contents1 Poetry of the Macchiaioli2 Premonitions of Naturalism Macchiaioli, this is how in 1862 an anonymous Italian reviewer of the “Gazzetta del Popolo” had defined, in the derogatory and popular sense of “scavezzacolli” (young and undisciplined person who leads a free and unruly life), those painters who around 1855 had given rise in …

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Neo-Impressionism

Neo-Impressionism is a pictorial movement that developed as part of the “reaction” to the fleeting nature of the Impressionist fragment, between 1884 and 1890. The name is due to the critic F. Fénéon who, in reviewing for the Belgian magazine “L’Art Moderne” the Grande Jatte by G. Seurat, presented at the Second Salon des Indépendants …

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Neoclassicism

Neoclassicism began around 1750 and ended with the end of the Napoleonic Empire in 1815, as a logical consequence of the Enlightenment culture and an era of great revolutions, it is proposed as an antithesis to the excesses of the Baroque and Rococo. What distinguishes the artistic style of these years is, thanks to the …

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Les Nabis

Les Nabis is a pictorial movement that arose in France in the late nineteenth century by a group of young artists, all born between 1860 and 1870: Maurice Denis (1870-1943), Pierre Bonnard (1867-1947), Edouard Vuillard (1868-1940), Aristide Maillol, Felix Vallotton, Paul-Elie Ranson (1861-1909), Jan Verkade, Ker Xavier Roussel, G. Lacombe. The term, chosen by the …

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Mir iskusstva

Mir iskusstva (Russian: «Мир искусства», IPA: [ˈmʲir ɪˈskustvə], World of Art) is an artistic movement founded in 1890 by a group of Russian intellectuals led by Sergei Diaghilev. The members of the group were scholars, art lovers, educated and refined, from a social background far removed from that of the Peredvizhniki, whose members came largely …

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Realism

In Art, Realism is a pictorial artistic current that can be defined as the attempt to represent matter truthfully, without artifice and avoiding speculative fiction and supernatural elements; it developed in the 1840s and, in France, sees in Gustave Courbet its main exponent; the figures of Honoré Daumier and Jean-François Millet, as well as Rosa …

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Impressionism

Table of contents1 Impressionism in paintingChronology and protagonists2 From the first attempts to the “Salon des refusés” of 18633 Other exhibitions [1876-86]4 The critical consecrationImpressionism between continuity and rupture5 Impressionism in other European countries Impressionism is the name used to indicate a common orientation of a group of artists (and not a real school of …

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Futurism

Futurism (from Italian: Futurismo) was an Italian literary, cultural, artistic and musical movement of the early 20th century, and one of the first European avant-garde movements. It had influence on related movements that developed in other countries of Europe, Russia, France, the United States of America and Asia. The Futurists explored all forms of expression: …

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Fauvism [fauvisme]

Fauvisme was a French painting movement of the first half of the twentieth century. The term fauves (“beasts”) was coined by the French critic L. Vauxcelles to indicate those painters, linked by a custom of life and work together (H. Matisse. M. Vlaminck. A. Derain, A. Marquet, A.E.O. Friesz, H.-Ch. Mansuin. Ch. Camoin. J. Puy. …

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Painting

Table of contents1 Painting techniques2 Painting styles3 Painting in the XIX century The term painting refers to the art of graphically depicting and representing something (such as a material object, a landscape, an abstract figment of the imagination) by means of lines, colors, masses, values, and tones on a mostly two-dimensional surface. By extension: a …

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Expressionism

Table of contents1 The precursors2 Germany3 Expressionism in Vienna4 Expressionism and Fauvism5 The war period5.1 Between the two wars (1919-39)5.1.1 Germany5.1.2 Belgium5.1.3 Holland5.1.4 France5.1.5 Mexico5.1.6 Italy Expressionism is an avant-garde artistic and literary movement, which has developed in Germany between the end of the 19th century and about 1925; in an uncomfortable and turbulent atmosphere …

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Divisionism

Divisionism is an Italian painting movement that developed between 1885 and 1915; it was essentially born from Impressionism and further developed its research on the decomposition of colors and light. Spread in several parts of Italy but with the main artistic center in Milan, was officially born in 1891, when the first pointillist works (and …

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Art Nouveau

The Art nouveau style took on different names in the various countries where it spread: in Italy floral or liberty style (from the English warehouses of A. Lasenby Liberty, which sold Art nouveau objects); in Germany Jugendstil, in Austria Sezessionstil, in Spain modernism, while Art nouveau is the name it took on in France and …

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Hydrocarbon

Table of contents1 Generalities and classes2 Characteristics3 Diffusion and use4 Hydrocarbon Chains5 Hydrocarbon Rings6 Role of hydrocarbons in chemistry7 C-H bond functionalization8 Origin of natural hydrocarbons8.1 Theory of inorganic origin8.2 Organic origin theory9 References Hydrocarbons are organic molecules consisting entirely of carbon and hydrogen, such as methane (CH4). The many covalent bonds between the atoms in hydrocarbons store …

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Measurement

Table of contents1 Measurement applications2 Measurement chain3 Measurement uncertainty3.1 Components of uncertainty3.2 Uncertainty estimation procedure4 Influence quantities in measurements4.1 Effects due to temperature4.2 Effects due to acceleration4.3 Effects due to vibrations4.4 Effects due to environmental pressure4.5 Effects due to commissioning of the transducer5 Measurement errors5.1 Random error5.2 Systematic error5.3 Gross error5.4 Static error5.4.1 Reading error5.4.2 …

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Immune system

The immune system is a complex integrated network of chemical and cellular mediators, biological structures and processes, developed over the course of evolution to defend the body against any form of chemical, traumatic or infectious insult to its integrity. To function properly, an immune system must be able to detect a wide variety of agents, …

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Major histocompatibility complex

The major histocompatibility complex (MHC) is a group of polymorphic genes consisting of 30 units (still identified), located on the short arm of chromosome 6 (in mice on chromosome 17). The most known encode proteins expressed on the cell membrane that have the function to be recognized by T lymphocytes, but also contains genes for …

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Immunology

Table of contents1 Specialized branches2 Immunology applications3 Humoral, cellular and specific immunity4 Antibody selection5 References Immunology is a branch of biology that deals with the immune system, studying aspects of the host’s defenses against infection and the adverse consequences of immune responses. Thus, immunology deals with the physiological functions of the immune system (and its …

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Insect [insecta]

Table of contents1 Morphology and anatomy of insects 2 External morphology3 Muscular and integumentary systems – Locomotion and flight4 Nervous system and sense organs5 Organs that produce sounds and light6 Digestive system7 Respiratory system8 Circulatory system9 Excretory and secretory systems10 Reproductive system11 Reproduction and prolification 12 Nidification, progeny supply, hunt and capture of the prey13 Post-embryonic development14 …

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Cost

Table of contents1 Cost-of-production theory of value2 Accounting cost3 Opportunity cost3.1 Identifying opportunity cost4 References Cost, in economics, business management and accounting, means the expression in currency or other numerical value of the value of goods and services used in the production or purchase of a good or service. It can be determined on the …

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Exoskeleton

An exoskeleton (from Greek έξω, éxō “outer” and σκελετός, skeletós “skeleton”), in zoology, is an external structure, more or less rigid, which acts as protection to the body of the animal and possibly as support to the organs. It is a term used in opposition to that of endoskeleton, which refers to the internal skeleton with which they are …

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Accelerometer

Table of contents1 Accelerometer specifications2 Fields of application of the accelerometers3 Types and classification of accelerometers3.1 Strain gauge accelerometers3.2 LVDT accelerometers3.3 Capacitive accelerometers3.4 Piezoresistive accelerometers3.5 Piezoelectric accelerometers3.6 Laser accelerometers3.7 MEMS accelerometers3.8 Gravimeter An accelerometer is a measuring instrument able of detecting and/or measuring acceleration (or the gravitational force), calculating the force measured with respect to the mass …

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Voicing

Voicing is whether the vocal folds vibrate or not. The sound /s/ is called voiceless because there is no vibration, and the sound /z/ is called voiced because the vocal folds do vibrate (you can feel on your neck if there is vibration.) Only three sounds in English have aspiration, the sounds /b/, /p/ and /t/. An extra puff of air …

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Pous

The pous (plural podes; from Greek: ποῦς, poûs) or Greek foot (plural feet) was a Greek unit of length. It had different values varying according to the city and the historical period. 100 podes made up one plethron, 600 podes made up a stade (the Greek furlong) and 5000 made up a milion (the Greek mile). The Greek pous also has long, …

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evaporation

Evaporation

Table of contents1 Natural evaporation2 Industrial evaporation In physics, evaporation is the change of state from liquid to aeriform (gas or vapor) which involves only the surface of the liquid. At boiling temperature, on the other hand, the boiling process occurs involving the entire volume of the liquid. Both processes represent the change of state …

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Threshold of hearing

Table of contents1 Threshold shift1.1 Characteristics of temporary threshold shift1.1.1 Mechanisms of temporary threshold shift1.2 Characteristics of permanent threshold shift1.2.1 Mechanisms of permanent threshold shift2 References The hearing threshold is the sound level below which a person’s ear is unable to detect any sound. For adults, 0 dB is the reference level. Sound level measurements in decibels …

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Resolution

Table of contents1 Resolution limitations1.1 Instrumental limitations1.2 Reading limitations1.3 Limitations of the measurand2 Resolution error2.1 Quantitative evaluation2.1.1 Reading digital instruments2.1.2 Reading analog instruments2.1.3 Background noise and interference2.1.4 Mechanical Limits2.1.5 Measurement discretization In metrology, the resolution of a measuring instrument is the ability to detect the smallest change in the value of a physical property that an instrument can detect. …

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Repeatability

Table of contents1 Repeatability Error2 Repeatability of a measuring instrument3 Repeatability of an actuator Repeatability is the degree of agreement between a series of measurements of the same measurand, when the individual measurements are made while leaving the measurement conditions unchanged. It is a static characteristic of an instrument defined as the ability of an instrument to …

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Reproducibility

Table of contents1 Reproducibility error2 Reproducibility of a measuring instrument In metrology, the term “reproducibility” is the degree of agreement between a series of measurements of the same measurand (the quantity being measured), when the individual measurements are made by changing one or more conditions. For example: by changing the method of measurement; by substituting …

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Center of mass

The center of mass of an object is the point at which the object can be balanced. Mathematically, it is the point at which the torques from the mass elements of an object sum to zero. The center of mass is useful because problems can often be simplified by treating a collection of masses as one mass …

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Mass

Table of contents1 Conservation of mass2 Inertial mass2.1 Newtonian definition2.2 Machian definition3 Gravitational mass4 Electromagnetic mass5 Negative mass6 Related keywords7 References The mass (or inertial mass, from Greek: μᾶζα, máza, barley cake, lump of dough) is a physical quantity that represents the amount of matter proper to material bodies that determines their dynamic behavior when subjected to the influence …

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Linearity

In metrology, linearity is actually a measure of the nonlinearity of the measurement instrument. When we talk about sensitivity, we assume that the input/output characteristic of the instrument to be approximately linear. But in practice, it is normally nonlinear, as shown in the figure below. Linearity is defined as the maximum deviation of the output of the measuring system from a …

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Matter

Table of contents1 Classification of matter2 Physical and chemical properties of matter3 Extensive and intensive properties4 States and phase transitions of matter5 The law of conservation of matter6 The matter in philosophy7 Related keywords8 References The matter is any substance (composed of various types of particles) that has mass, inertia, and occupies physical space by …

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Sensitivity

In Metrology, the sensitivity of a measuring instrument is that metrological characteristic that provides information on the instrument’s ability to detect small variations in the input quantity; in other words: the increment of the output signal (or response) to the increment of the input measured signal. It can be defined also as the ratio of the incremental output and the incremental input. …

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Accuracy vs Precision

The difference between precision and accuracy needs to be understood carefully. Precision means repetition of successive readings, but it does not guarantee accuracy; successive readings may be close to each other, but far from the true value. On the other hand, an accurate instrument has to be precise also, since successive readings must be close to the true value …

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Precision

In metrology, precision indicates the repeatability or reproducibility of an instrument (but does not indicate accuracy). In other words is the degree of the repetitiveness of the measuring process of a quantity made by using the same method, under similar conditions. In error theory, precision is the degree of “convergence” (or “dispersion”) of individually collected data (sample) with respect to the mean value of …

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Accuracy

Table of contents1 Measurement accuracy2 Relativity of accuracy3 Instrumental accuracy4 Accuracy and costs In error theory, accuracy is the degree of correspondence of the theoretical data, which can be inferred from a series of measured values (data sample), with the real or reference data, i.e. the difference between the average sample value and the true or reference. Indicates the …

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Photon

Table of contents1 Historical development2 Related keywords3 References A photon (from the Greek phõs phōtṓs, light, on the model of electron) is the smallest quantity (quantum) of energy that can be transported and it was the realization that light traveled in discrete quanta that were the origins of Quantum Theory. A photon is massless, has no electric …

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Photonics

Photonics is the field of optics that studies the possibility of controlling flows of photons, and to realize devices similar to electronic ones but using photons instead of electrons. In the field of telecommunications, the term is used to indicate the set of technologies used for the generation, transmission, detection and processing of modulated signals …

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