Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

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Revista de logopedia, foniatría y audiología

Resumen basado en el de la publicaciónResumen en inglésSe presenta un estudio cuyo objetivo fue determinar la utilidad de los potenciales evocados visuales con patrón invertido (PEVp) en el diagnóstico de la dislexia. Se estudiaron 16 niños disléxicos del Instituto Nacional de Rehabilitación en México D.F. Se realizaron estudios de agudeza visual, la prueba WISC-R y PEVp. Los disléxicos ingresaron en un programa de terapia de aprendizaje durante 6 meses, así se obtuvieron y compararon mediciones neuropsicológicas y neurofisiológicas al inicio y al concluir el programa terapéutico. Se concluye que las amplitudes en los PEVp se deben tener en cuenta para poder entender los mecanismos de procesamiento visual y de compensación cerebral en pacientes con dislexia. Se recomienda una terapia específica para los problemas de lectoescritura de acuerdo con el sujeto disléxicoES

Compilación de Proyectos de Investigacion de 1984-2002

Instituto Politecnico Nacional. UPIICS

Tópicos selectos de ciencias químicas

La Química es una de las ramas de la ciencia que ha tomado mayor importancia en las últimas décadas. Es imposible no pensar en ella al escuchar los avances milagrosos de fármacos, materiales inteligentes, tecnología nanométrica, computadoras cuánticas o procesos catalíticos, donde la transformación controlada de la materia ha logrado la creación de sustancias con propiedades hechas a medida. En ese sentido, el papel de la Facultad de Química, en la formación de profesionales de dicha área, cobra una importancia superlativa; además del compromiso y la responsabilidad de formar sujetos no sólo con conocimiento, sino desarrollar su conciencia social y ecológica, indispensables para la situación actual y futura.Universidad Autónoma del Estado de México

Measurement of an excess in the yield of J/ψ at very low pT in Pb–Pb collisions at √sNN = 2.76 TeV

We report on the first measurement of an excess in the yield of J/ψ at very low transverse momentum (pT<0.3 GeV/c) in peripheral hadronic Pb-Pb collisions at sNN−−−√ = 2.76 TeV, performed by ALICE at the CERN LHC. Remarkably, the measured nuclear modification factor (RAA) of J/ψ in the rapidity range 2.5<y<4 reaches about 7 (2) in the pT range 0-0.3 GeV/c in the 70-90% (50-70%) centrality class. The J/ψ production cross section associated with the observed excess is obtained under the hypothesis that coherent photoproduction of J/ψ is the underlying physics mechanism. If confirmed, the observation of J/ψ coherent photoproduction in Pb-Pb collisions at impact parameters smaller than twice the nuclear radius opens new theoretical and experimental challenges and opportunities. In particular, coherent photoproduction accompanying hadronic collisions may provide insight into the dynamics of photoproduction and nuclear reactions, as well as become a novel probe of the Quark-Gluon Plasma

Measurement of transverse energy at midrapidity in Pb–Pb collisions at √sNN = 2.76 TeV

We report the transverse energy (ET) measured with ALICE at midrapidity in Pb-Pb collisions at sNN−−−√ = 2.76 TeV as a function of centrality. The transverse energy was measured using identified single particle tracks. The measurement was cross checked using the electromagnetic calorimeters and the transverse momentum distributions of identified particles previously reported by ALICE. The results are compared to theoretical models as well as to results from other experiments. The mean ET per unit pseudorapidity (η), ⟨dET/dη⟩, in 0-5% central collisions is 1737 ± 6(stat.) ± 97(sys.) GeV. We find a similar centrality dependence of the shape of ⟨dET/dη⟩ as a function of the number of participating nucleons to that seen at lower energies. The growth in ⟨dET/dη⟩ at the LHC sNN−−−√ exceeds extrapolations of low energy data. We observe a nearly linear scaling of ⟨dET/dη⟩ with the number of quark participants. With the canonical assumption of a 1 fm/c formation time, we estimate that the energy density in 0-5% central Pb-Pb collisions at sNN−−−√ = 2.76 TeV is 12.3 ± 1.0 GeV/fm3\xspace and that the energy density at the most central 80 fm2 of the collision is at least 21.5 ± 1.7 GeV/fm3. This is roughly 2.3 times that observed in 0-5% central Au-Au collisions at sNN−−−√ = 200 GeV

Centrality dependence of the charged-particle multiplicity density at midrapidity in Pb–Pb collisions at √sNN = 5.02 TeV

The pseudorapidity density of charged particles (dNch/dη) at mid-rapidity in Pb-Pb collisions has been measured at a center-of-mass energy per nucleon pair of sNN−−−√ = 5.02 TeV. It increases with centrality and reaches a value of 1943±54 in |η|<0.5 for the 5% most central collisions. A rise in dNch/dη as a function of sNN−−−√ for the most central collisions is observed, steeper than that observed in proton-proton collisions and following the trend established by measurements at lower energy. The centrality dependence of dNch/dη as a function of the average number of participant nucleons, ⟨Npart⟩, calculated in a Glauber model, is compared with the previous measurement at lower energy. A constant factor of about 1.2 describes the increase in 2⟨Npart⟩⟨dNch/dη⟩ from sNN−−−√ = 2.76 TeV to sNN−−−√ = 5.02 TeV for all centrality intervals, within the measured range of 0-80% centrality. The results are also compared to models based on different mechanisms for particle production in nuclear collisions

Anisotropic flow of charged particles in Pb–Pb collisions at √sNN = 5.02 TeV

We report the first results of elliptic (v2), triangular (v3) and quadrangular flow (v4) of charged particles in Pb-Pb collisions at sNN−−−√=5.02 TeV with the ALICE detector at the CERN Large Hadron Collider. The measurements are performed in the central pseudorapidity region |η|<0.8 and for the transverse momentum range 0.2<pT<5 GeV/c. The anisotropic flow is measured using two-particle correlations with a pseudorapidity gap greater than one unit and with the multi-particle cumulant method. Compared to results from Pb-Pb collisions at sNN−−−√=2.76 TeV, the anisotropic flow coefficients v2, v3 and v4 are found to increase by (3.0±0.6)%, (4.3±1.4)% and (10.2±3.8)%, respectively, in the centrality range 0-50%. This increase can be attributed mostly to an increase of the average transverse momentum between the two energies. The measurements are found to be compatible with hydrodynamic model calculations. This comparison provides a unique opportunity to test the validity of the hydrodynamic picture and the power to further discriminate between various possibilities for the temperature dependence of shear viscosity to entropy density ratio of the produced matter in heavy-ion collisions at the highest energies