Cloud computing Un article de Wikipédia, l'encyclopédie libre. Le cloud computing, ou l’informatique en nuage ou nuagique ou encore l’infonuagique (au Québec), est l'exploitation de la puissance de calcul ou de stockage de serveurs informatiques distants par l'intermédiaire d'un réseau, généralement Internet. Ces serveurs sont loués à la demande, le plus souvent par tranche d'utilisation selon des critères techniques (puissance, bande passante, etc.) mais également au forfait. Terminologie[modifier | modifier le code] En France, la Commission générale de terminologie et de néologie précise qu'il s'agit d'une forme particulière de gérance de l'informatique, dans laquelle l'emplacement et le fonctionnement dans le nuage ne sont pas portés à la connaissance des clients. Les francisations « informatique en nuage », « informatique dématérialisée », ou plus rarement « infonuagique » sont également utilisées. Principes - le Nuage[modifier | modifier le code] Services[modifier | modifier le code]
Pearson product-moment correlation coefficient In statistics, the Pearson product-moment correlation coefficient (/ˈpɪərsɨn/) (sometimes referred to as the PPMCC or PCC or Pearson's r) is a measure of the linear correlation (dependence) between two variables X and Y, giving a value between +1 and −1 inclusive, where 1 is total positive correlation, 0 is no correlation, and −1 is total negative correlation. It is widely used in the sciences as a measure of the degree of linear dependence between two variables. It was developed by Karl Pearson from a related idea introduced by Francis Galton in the 1880s. Examples of scatter diagrams with different values of correlation coefficient (ρ) Several sets of (x, y) points, with the correlation coefficient of x and y for each set. Definition Pearson's correlation coefficient between two variables is defined as the covariance of the two variables divided by the product of their standard deviations. For a population where: Then the formula for ρ can also be written as where and
Communication verbale, non verbale et paraverbale Plan · La communication, en quelques mots · La communication interpersonnelle · Communication verbale : bonheur/malheur ? · Communication non verbale ? · Les obstacles à la communication · L’écoute : Passive/Active · Synthèse et quelques conseils pratiques · En conclusion…quelques citations… · Webographie La communication : un concept fourre tout ? La "communication" est le processus de transmission d’informations. La communication peut par ailleurs renvoyer à l'ensemble des moyens et techniques permettant la diffusion d'un message auprès d'une audience plus ou moins vaste et hétérogène. Sur un plan purement théorique, la communication est une interdiscipline. Il y a également la dimension humaine : qui englobe les interactions entre les personnes que ce soit à au niveau verbal ou non verbal. Bref la communication est un terme générique. Communication interpersonnelle (humaine) ? La communication interpersonnelle est basée sur l’échange d’un message entre 1 émetteur et 1 récepteur. 1- Le silence
List of particles This is a list of the different types of particles found or believed to exist in the whole of the universe. For individual lists of the different particles, see the individual pages given below. Elementary particles Fermions Fermions are one of the two fundamental classes of particles, the other being bosons. Fermions have half-integer spin; for all known elementary fermions this is 1⁄2. Quarks Leptons Bosons Bosons are one of the two fundamental classes of particles, the other being fermions. The fundamental forces of nature are mediated by gauge bosons, and mass is believed to be created by the Higgs Field. The graviton is added to the list although it is not predicted by the Standard Model, but by other theories in the framework of quantum field theory. Hypothetical particles Supersymmetric theories predict the existence of more particles, none of which have been confirmed experimentally as of 2014: Composite particles Hadrons
Neutron The neutron is a subatomic hadron particle that has the symbol n or n0. Neutrons have no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen-1, the nucleus of every atom consists of at least one or more of both protons and neutrons. Protons and neutrons are collectively referred to as "nucleons". Since interacting protons have a mutual electromagnetic repulsion that is stronger than their attractive nuclear interaction, neutrons are often a necessary constituent within the atomic nucleus that allows a collection of protons to stay atomically bound (see diproton & neutron-proton ratio). Neutrons bind with protons and one another in the nucleus via the nuclear force, effectively stabilizing it. The number of neutrons in the nucleus of an atom is referred to as its neutron number, which reveals the specific isotope of that atom. The neutron has been key to the production of nuclear power. Discovery Intrinsic properties
Quark A quark (/ˈkwɔrk/ or /ˈkwɑrk/) is an elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. Due to a phenomenon known as color confinement, quarks are never directly observed or found in isolation; they can be found only within hadrons, such as baryons (of which protons and neutrons are examples), and mesons. For this reason, much of what is known about quarks has been drawn from observations of the hadrons themselves. The quark model was independently proposed by physicists Murray Gell-Mann and George Zweig in 1964. Quarks were introduced as parts of an ordering scheme for hadrons, and there was little evidence for their physical existence until deep inelastic scattering experiments at the Stanford Linear Accelerator Center in 1968. Accelerator experiments have provided evidence for all six flavors. Classification
Graviton Theory The three other known forces of nature are mediated by elementary particles: electromagnetism by the photon, the strong interaction by the gluons, and the weak interaction by the W and Z bosons. The hypothesis is that the gravitational interaction is likewise mediated by an – as yet undiscovered – elementary particle, dubbed as the graviton. In the classical limit, the theory would reduce to general relativity and conform to Newton's law of gravitation in the weak-field limit. Gravitons and renormalization When describing graviton interactions, the classical theory (i.e., the tree diagrams) and semiclassical corrections (one-loop diagrams) behave normally, but Feynman diagrams with two (or more) loops lead to ultraviolet divergences; that is, infinite results that cannot be removed because the quantized general relativity is not renormalizable, unlike quantum electrodynamics. Comparison with other forces Gravitons in speculative theories See also
Photon Nomenclature In 1900, Max Planck was working on black-body radiation and suggested that the energy in electromagnetic waves could only be released in "packets" of energy. In his 1901 article  in Annalen der Physik he called these packets "energy elements". The word quanta (singular quantum) was used even before 1900 to mean particles or amounts of different quantities, including electricity. Physical properties The cone shows possible values of wave 4-vector of a photon. A photon is massless,[Note 2] has no electric charge, and is stable. Photons are emitted in many natural processes. The energy and momentum of a photon depend only on its frequency (ν) or inversely, its wavelength (λ): where k is the wave vector (where the wave number k = |k| = 2π/λ), ω = 2πν is the angular frequency, and ħ = h/2π is the reduced Planck constant. Since p points in the direction of the photon's propagation, the magnitude of the momentum is Experimental checks on photon mass
Baryon A baryon is a composite subatomic particle made up of three quarks (as distinct from mesons, which comprise one quark and one antiquark). Baryons and mesons belong to the hadron family, which are the quark-based particles. The name "baryon" comes from the Greek word for "heavy" (βαρύς, barys), because, at the time of their naming, most known elementary particles had lower masses than the baryons. As quark-based particles, baryons participate in the strong interaction, whereas leptons, which are not quark-based, do not. Until recently, it was believed that some experiments showed the existence of pentaquarks — "exotic" baryons made of four quarks and one antiquark. The particle physics community as a whole did not view their existence as likely in 2006, and in 2008, considered evidence to be overwhelmingly against the existence of the reported pentaquarks. Background Baryons, along with mesons, are hadrons, meaning they are particles composed of quarks. Baryogenesis
Scientists reach the ultimate goal: Controlling chirality in carbon nanotubes An ultimate goal in the field of carbon nanotube research is to synthesise single-walled carbon nanotubes (SWNTs) with controlled chiralities. Twenty years after the discovery of SWNTs, scientists from Aalto University in Finland, A.M. Prokhorov General Physics Institute RAS in Russia and the Center for Electron Nanoscopy of Technical University of Denmark (DTU) have managed to control chirality in carbon nanotubes during their chemical vapor deposition synthesis Carbon nanotube structure is defined by a pair of integers known as chiral indices (n,m), in other words, chirality. "Chirality defines the optical and electronic properties of carbon nanotubes, so controlling it is a key to exploiting their practical applications," says Professor Esko I. Over the years, substantial progress has been made to develop various structure-controlled synthesis methods.
DNA strands that select nanotubes are first step to a practical 'quantum wire' DNA, a molecule famous for storing the genetic blueprints for all living things, can do other things as well. In a new paper, researchers at the National Institute of Standards and Technology (NIST) describe how tailored single strands of DNA can be used to purify the highly desired "armchair" form of carbon nanotubes. Armchair-form single wall carbon nanotubes are needed to make "quantum wires" for low-loss, long distance electricity transmission and wiring. Single-wall carbon nanotubes are usually about a nanometer in diameter, but they can be millions of nanometers in length. Chirality plays an important role in nanotube properties. Armchair carbon nanotubes could revolutionize electric power systems, large and small, Tu says. Separating one particular chirality of nanotube from all others starts with coating them to get them to disperse in solution, as, left to themselves, they'll clump together in a dark mass.