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Spectroscopy

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 the interaction between matter and electromagnetic radiation and an …

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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

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 deductions. Since the deductive method always starts from a postulate or an axiom, that is, from an …

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Reason

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 with such characteristically human activities as philosophy, science, language, mathematics, and art, and is normally considered to be a distinguishing ability possessed by humans. The reasoning is a …

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Apple cider vinegar

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 it is usually more turbid than wine vinegar and …

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Friction

Friction can be defined as the force between surfaces in contact that resists their relative tangential motion (slipping). Friction is a passive resistance that tends to hinder the relative motion of two bodies in contact. Passive resistance, which produces the loss of dynamic work in contact between bodies in relative motion, can be distinguished in various …

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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 particles are linked (weakly) to each other. On the other hand, as liquids and …

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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]

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 superconductor. Superfluidity was discovered by Pëtr Leonidovič Kapica, John …

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Electricity

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 molecular scale: protons in the nucleus of ionized atoms or molecules, and electrons. The typical macroscopic effects of …

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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 electromagnetic phenomena goes instead under the name …

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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

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 again. This process, theoretically, can be repeated several times according to the qualities …

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plastic

Plastic

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 to be made with different molding methods. Plastics are high molecular weight organic materials, that is, made up of molecules …

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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

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 initial velocity because it has been imprinted a force of impulsive type and does not have …

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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

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 theory of general relativity, according to which the trajectory of electromagnetic radiation, such as light, is …

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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

A solid is a state of matter in which atoms or molecules are tightly bound together by powerful forces thereby creating a rigid body (with a defined geometric shape and volume). In other words, a solid is a material object that is in a condensed state characterized by resistance to deformation and changes in volume. The branch …

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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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Time

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 change or the interval in which a change occurs. It is impossible to know that time has passed unless …

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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 good, capable of being exchanged for other goods (bartering …

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Microeconomics

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 of the economy: individuals, firms, and industries. Together with macroeconomics, which studies systems …

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Political economy

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 needs are unlimited, each individual or each group of individuals must make choices: political economy studies the forms that human behavior (individual or …

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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

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 wise man’s ability to deal with issues inherent to …

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Arabic 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: Arabic. The term includes both the so-called …

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Jewish philosophy

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 but who were united by two common characteristics: their Jewish ethnicity and their …

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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

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 specific problems over the elaboration of broad and comprehensive systems. From the school of G.E. Moore to the Tractatus 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

Philosophy can be defined as a form of knowledge that, despite the wide variety of its expressions, exhibits as almost constant characteristics two vocations: one towards universality and one towards the prescription of wisdom. The former manifests itself in two ways: philosophy is presented as the perfect form of knowledge, in any case as the …

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Electric current

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

Stability

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 scope. Definitions (physics) (architecture) (technology) (engineering) ability of a physical system to resist external forces and stresses; (chemistry) property of a chemical system to remain …

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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

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 triggered by an event-stimulus relevant to the interests of the individual, have a time course and are activated by internal …

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marius masalar music

Music

Music (from the Greek noun μουσική, mousike; “art of the Muses”) is the product of devising and producing art, through the use of instruments or the voice, a succession of sounds that tend to be pleasing to the ear. More technically, music consists in the conception and realization of sounds, timbres and silences in the …

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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

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 egocentricity, despair, dissatisfaction with the repetitive …

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Macchiaioli

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 Florence, in the context of the transition from the romantic …

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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

Impressionism is the name used to indicate a common orientation of a group of artists (and not a real school of painting) who worked in France in the second half of the 19th century. The term (which later was extended to other areas of culture, in particular to qualify a trend of modern music) originates …

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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

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 pictorial trend that is distinguished by style, author, country, era, or otherwise. …

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Expressionism

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 that preceded the war of 1914; from a pictorial point of view, it appeared as a clear reaction to Impressionism, whose objectivity and scientific optimism were …

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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

Hydrocarbons are organic molecules consisting entirely of carbon and hydrogen, such as methane (CH4). The many covalent bonds between the atoms in hydrocarbons store a great amount of energy, which releases when these molecules burn (oxidize). Methane is the simplest hydrocarbon molecule, with a central carbon atom bonded to four different hydrogen atoms. The shape of its electron orbitals …

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Measurement

In metrology the term measurement is closely associated with all the activities about scientific, industrial, commercial, and human aspects. It is defined as the assignment of a number to a characteristic of an object or event, which can be compared with other objects or events. The knowledge of the reality that surrounds us is based on the …

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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

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 components) both during an illness and in a healthy condition, as well as malfunctions of …

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Insect [insecta]

Insects (or Insecta in scientific Latin; from the word insectum “cut, divided”) belong to the Class of the Arthropoda Phylum, which, after the systematic revisions from the last decades of the 20th century, was included in the Hexapoda Superclass, they are considered as the largest group in the animal kingdom on Earth: the species described are over a million and their …

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Cost

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 basis of internal evaluations of the economic entity that holds it or in economic transactions …

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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

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 of the object (force per unit of mass). Therefore the operating principle of an accelerometer is based on the detection of the inertia of a mass when it is subjected to an …

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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

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 from liquid to aeriform are collectively identified …

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Threshold of hearing

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 are generally referenced to a standard threshold of hearing at 1000 Hz for the human ear which can be stated in terms of sound intensity: \[I_0=10^{-12}\;\dfrac{\textrm{W}}{\textrm{m}^2}=10^{-16}\;\dfrac{\textrm{W}}{\textrm{cm}^2}\] …

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Resolution

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. It also represents a static characteristic of an instrument. The resolution of an instrument can also be defined as the minimum incremental value of the input signal that is required to cause …

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Repeatability

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 reproduce a group of measurements of the same measured quantity, made by the same observer, using the …

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Reproducibility

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 the operator for the measurement; Replacing the measuring instrument; moving …

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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

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 of external forces. In classical mechanics the term mass can refer to three different scalar physical quantities, distinct from each other: …

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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

The matter is any substance (composed of various types of particles) that has mass, inertia, and occupies physical space by having volume. This definition, adequate for macroscopic physics, the object of study of mechanics and thermodynamics, does not fit well with modern theories in the microscopic realm, proper to atomic and subatomic physics. In physics, …

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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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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

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 proximity of the value found to the real one. It is a qualitative …

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Photon

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 charge, and is a stable particle with two …

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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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Harm

Harm is a moral and legal concept, that is, the consequence of an action or event that causes the quantitative or functional reduction of an asset, a value, an object, property or anything else that has an economic, emotional, and moral value. So, in other words, the harm may concern material and physical assets (such as: …

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