1,930 research outputs found

    First GPS Baseline Results from the North Andes

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    The CASA UNO GPS (Global Positioning System) experiment (January-February 1988) has provided the first epoch baseline measurements for the study of plate motions and crustal deformation in and around the North Andes. Two dimensional horizontal baseline repeatabilities are as good as 5 parts in 108 for short baselines (100-1000km), and better than3 parts in 108 for long baselines (\u3e1000km). Vertical repeatabilities are typically 4 -6 cm, with a weak dependence on baseline length. The expected rate of plate convergence across the Colombia Trench is 6-8 cm/yr, which should be detectable by the repeat experiment planned for 1991. Expected deformation rates within the North Andes are of the order of 1 cm/yr, which may be detectable with the 1991 experiment

    Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

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    The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum

    Identificación y caracterización de grupos biológicos (comunidades hidrobiológicas, macroinvertebrados, plantas acuáticas, peces, anfibios, plantas terrestres, reptiles, aves y mamíferos), en el complejo ventana piloto de humedales de Paz de Ariporo-Hato Corozal

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    Este documento es resultado de la ejecución del Contrato 14-13-014-237PS entre el Instituto Humboldt y la Fundación Omacha, firmado en el marco del Convenio 005 (13-014) entre el Instituto Humboldt y el Fondo Adaptación. Contiene la propuesta para la identificación del límite funcional de la ventana piloto de humedales Paz de Ariporo-Hato Corozal, donde se estudiaron en los principales tipos de humedales naturales asociados a las cuencas de los ríos Ariporo y Chire (caños, cañadas, bosques de rebalse, matorrales inundables y cuerpos lénticos como esteros, lagunas de rebalse, bajos y madreviejas) la composición, estructura y uso del hábitat de los grupos biológicos asociados, tanto a los cuerpos de aguas como en las zonas transicionales acuático terrestres.BogotáSubdirección de Servicios Científicos y Proyectos Especiale
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