55,367 research outputs found
Présentation de: Sanchez-Palencia-Françoise, "Dialectique dans les sciences et systèmes dynamiques"
No full textDestiné aussi bien au profane qu'au spécialiste, ce livre est une invitation à réfléchir l'évolution biologique hors du cadre élémentaire de la survivance des plus aptes, à partir des systèmes dynamiques et de leur capacité à engendrer des structures nouvelles. Avec des mots simples et à partir de cas concrets, Évariste Sanchez-Palencia et Jean-Pierre
Françoise nous expliquent comment des mécanismes naturels sans le moindre finalisme conduisent à la formation de configurations stables de nature variée, constante ou pulsante, mettant en œuvre une diversité d'espèces en interaction.
Ce faisant, ils nous accompagnent sur le chemin d'une réflexion plus vaste à partir du principe de causalité différée, sur la pertinence de la méthode dialectique pour appréhender l'évolution biologique, notamment au travers de la puissance créatrice de la contradiction. La méthode dialectique, celle de Engels, nous est présentée alors comme méthode de recherche et d'interprétation dont la portée conduit à un renouvellement de la connaissance scientifique et de son évolution.
Évariste Sanchez-Palencia est un chercheur français en mécanique théorique, mathématique appliquée et épistémologie. Il est directeur émérite du CNRS et membre de l'Académie des sciences.
Jean-Pierre Françoise est professeur émérite de mathématiques à Sorbonne Université. Spécialiste des équations différentielles et des systèmes dynamiques, il a contribué à la physique mathématique et à la modélisation mathématique dans les sciences du vivant. Il est actuellement Président de la société
francophone de biologie théorique
Sanchez, J. P.
No full textPhotograph from the C.R. Savage Portrait Studio. Name associated with the photograph: J. P. Sanche
Searches for B0(s)→J/ψppˉ and B+→J/ψppˉπ+ decays
No full textThe results of searches for B0(s)→J/ψ pp¯ and B + → J/ψ p p¯ π+ decays are reported. The analysis is based on a data sample, corresponding to an integrated luminosity of 1.0 fb−1 of pp collisions, collected with the LHCb detector. An excess with 2.8 σ significance is seen for the decay B0s→J/ψ pp¯ and an upper limit on the branching fraction is set at the 90 % confidence level: B(B0s→J/ψ pp¯) < 4.8 × 10−6, which is the first such limit. No significant signals are seen for B0 → J/ψ pp¯ and B+ → J/ψ pp¯ π + decays, for which the corresponding limits are set: B(B0→J/ψ pp¯) < 5.2 × 10−7, which significantly improves the existing limit; and B(B+→J/ψ pp¯π+) < 5.0 × 10−7, which is the first limit on this branching fraction
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
Heliotropic dust rings for Earth climate engineering
No full textThis paper examines the concept of a Sun-pointing elliptical Earth ring comprised of dust grains to offset global warming. A new family of non-Keplerian periodic orbits, under the effects of solar radiation pressure and the Earth's J(2) oblateness perturbation, is used to increase the lifetime of the passive cloud of particles and, thus, increase the efficiency of this geoengineering strategy. An analytical model is used to predict the orbit evolution of the dust ring due to solar-radiation pressure and the J(2) effect. The attenuation of the solar radiation can then be calculated from the ring model. In comparison to circular orbits, eccentric orbits yield a more stable environment for small grain sizes and therefore achieve higher efficiencies when the orbit decay of the material is considered. Moreover, the novel orbital dynamics experienced by high area-to-mass ratio objects, influenced by solar radiation pressure and the J(2) effect, ensure the ring will maintain a permanent heliotropic shape, with dust spending the largest portion of time on the Sun facing side of the orbit. It is envisaged that small dust grains can be released from a circular generator orbit with an initial impulse to enter an eccentric orbit with Sun-facing apogee. Finally, a lowest estimate of 1 x 10(12) kg of material is computed as the total mass required to offset the effects of global warming
Production of J/ψ and Υ mesons in pp collisions at s√=8 TeV
No full textThe production of J/ψ and Υ mesons in pp collisions at s√=8 TeV is studied with the LHCb detector. The J/ψ and Υ mesons are reconstructed in the μ + μ − decay mode and the signal yields are determined with a fit to the μ + μ − invariant mass distributions. The analysis is performed in the rapidity range 2. 0 < y < 4. 5 and transverse momentum range 0 < p T < 14 (15) GeV/c of the J/ψ (Υ) mesons. The J/ψ and Υ production cross-sections and the fraction of J/ψ mesons from b-hadron decays are measured as a function of the meson p T and y
[Leis etc. forales]
No full textApéndice: p. 135-189SignaturizadoIncluye los Fueros de Béjar, Ledesma, Alba de Tormes y otros documentos legale
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
La arqueología de la ciudad de México en un viaje por el metro. Conferencia Magistral<p>XXIII Simposio Román Piña Chan.Zonas Arqueológicas en Contextos Urbanos<p>
No full textPedro Francisco Sanchez Nava expone la relación entre la historia de la construcción del metro y los hallazgos arqueológicos que se han dado en la construcción de este sistema de transporte, después de explicar los procesos contructivos, hace un breve recorrido por 11 líneas del metro a través de las piezas y vestigios encontrados.</p
[Leyes, etc. forales]
No full textApéndice: p. 135-189.Copia digital. España : Ministerio de Cultura. Subdirección General de Coordinación Bibliotecaria, d2024Rústica.Signaturizado.Registro de la Propiedad Intelectual: Ley de 1847: [sin número]; n. de solicitud de ingreso: "5127"; fecha y datos de ingreso: "Noviembre 70"; firma del depositante: "Como apoderado de la viudad y padre del tutor, Rafael Rodríguez"Incluye los Fueros de Béjar, Ledesma, Alba de Tormes y otros documentos legale
- …
