Univers de GödelL'univers de Gödel est une solution aux équations de la relativité générale publiée par le mathématicien Kurt Gödel en 1949. Cette solution possède plusieurs propriétés remarquables. Elle décrit un univers en rotation, c'est-à-dire un univers qui possède une direction privilégiée que l'on peut localement assimiler à un axe de rotation. Par ailleurs, la structure de l'espace-temps permet l'existence de courbes de genre temps refermées sur elles-mêmes. Ces travaux sont à l'origine de la recherche d'un plus grand nombre de solutions exactes aux équations d'Einstein.
Movie projectorA movie projector is an opto-mechanical device for displaying motion picture film by projecting it onto a screen. Most of the optical and mechanical elements, except for the illumination and sound devices, are present in movie cameras. Modern movie projectors are specially built video projectors (see also digital cinema). Many projectors are specific to a particular film gauge and not all movie projectors are film projectors since the use of film is required. The main precursor to the movie projector was the magic lantern.
Present valueIn economics and finance, present value (PV), also known as present discounted value, is the value of an expected income stream determined as of the date of valuation. The present value is usually less than the future value because money has interest-earning potential, a characteristic referred to as the time value of money, except during times of zero- or negative interest rates, when the present value will be equal or more than the future value. Time value can be described with the simplified phrase, "A dollar today is worth more than a dollar tomorrow".
Kerr metricThe Kerr metric or Kerr geometry describes the geometry of empty spacetime around a rotating uncharged axially symmetric black hole with a quasispherical event horizon. The Kerr metric is an exact solution of the Einstein field equations of general relativity; these equations are highly non-linear, which makes exact solutions very difficult to find. The Kerr metric is a generalization to a rotating body of the Schwarzschild metric, discovered by Karl Schwarzschild in 1915, which described the geometry of spacetime around an uncharged, spherically symmetric, and non-rotating body.
Bruit au travailLe bruit est une sensation auditive désagréable ou gênante. Au-delà d’un certain seuil, quand le niveau sonore est très élevé, tous les sons sont dangereux pour la santé. Au travail, le bruit peut avoir de multiples origines : machines, outils, véhicules... Le niveau du bruit se mesure en décibels . Selon l’Institut National de Recherche et de Sécurité, pour une journée de travail de 8 heures, l’ouïe est en danger à partir de 80 dB(A).
Likelihood principleIn statistics, the likelihood principle is the proposition that, given a statistical model, all the evidence in a sample relevant to model parameters is contained in the likelihood function. A likelihood function arises from a probability density function considered as a function of its distributional parameterization argument.
Musique classiquethumb|250px|Une vingtaine de compositeurs de musique classique, parmi les plus importants couvrant la période du .(De gauche à droite, de haut en bas : — Antonio Vivaldi, Jean-Sébastien Bach, Georg Friedrich Haendel, Wolfgang Amadeus Mozart, Ludwig van Beethoven — Gioachino Rossini, Felix Mendelssohn, Frédéric Chopin, Richard Wagner, Giuseppe Verdi — Johann Strauss II, Johannes Brahms, Georges Bizet, Piotr Ilitch Tchaïkovski, Antonín Dvořák — Edvard Grieg, Edward Elgar, Sergueï Rachmaninov, George Gershwin, Aram Khatchatourian.
Matrice densitéEn physique quantique, la matrice densité, souvent représentée par , est un objet mathématique introduit par le mathématicien et physicien John von Neumann permettant de décrire l'état d'un système physique. Elle constitue une généralisation de la formulation d'un état physique à l'aide d'un ket , en permettant de décrire des états plus généraux, appelés mélanges statistiques, que la précédente formulation ne permettait pas de décrire.
Compound Poisson distributionIn probability theory, a compound Poisson distribution is the probability distribution of the sum of a number of independent identically-distributed random variables, where the number of terms to be added is itself a Poisson-distributed variable. The result can be either a continuous or a discrete distribution. Suppose that i.e., N is a random variable whose distribution is a Poisson distribution with expected value λ, and that are identically distributed random variables that are mutually independent and also independent of N.
Pharmaceutical formulationPharmaceutical formulation, in pharmaceutics, is the process in which different chemical substances, including the active drug, are combined to produce a final medicinal product. The word formulation is often used in a way that includes dosage form. Formulation studies involve developing a preparation of the drug which is both stable and acceptable to the patients. For orally administered drugs, this usually involves incorporating the drug into a tablet or a capsule.
