981 research outputs found

    Development of a Tabletop Setup for the Transient Current Technique Using Two-Photon Absorption in Silicon Particle Detectors

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    The transient current technique (TCT) is widely used in the field of silicon particle detector development. So far, only laser wavelengths with a photon energy larger than or similar to the silicon bandgap (single photon absorption) were used. Recently, measurements using two-photon absorption (TPA) for silicon detector testing have been carried out for the first time. Excess carriers are only created at the focal point of the laser beam and thus resolution in all three spatial directions could be achieved. The resolution perpendicular to the incident laser beam could be increased roughly by a factor of 10. First measurements using this new method were performed at the Singular Laser Facility of Universidad del Pais Vasco (UPV)/Euskal Herriko Unibertzitatea (EHU). Following the initial success of the method, a compact TPA-TCT setup is under development. A first description of the setup and laser system is presented in this articleThis work was supported in part by the Spanish Ministry of Economy and Competitiveness (MINECO) under Grant FPA2013-48387-C6-1-P and in part by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Research under Grant 05E15CH

    Deep learning-based super-resolution and de-noising for XMM-newton images

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    The field of artificial intelligence based image enhancement has been rapidly evolving over the last few years and is able to produce impressive results on non-astronomical images. In this work, we present the first application of Machine Learning based super-resolution (SR) and de-noising (DN) to enhance X-ray images from the European Space Agency's XMM-Newton telescope. Using XMM-Newton images in band [0.5, 2] keV from the European Photon Imaging Camera pn detector (EPIC-pn), we develop XMM-SuperRes and XMM-DeNoise - deep learning-based models that can generate enhanced SR and DN images from real observations. The models are trained on realistic XMM-Newton simulations such that XMM-SuperRes will output images with two times smaller point-spread function and with improved noise characteristics. The XMM-DeNoise model is trained to produce images with 2.5× the input exposure time from 20 to 50 ks. When tested on real images, DN improves the image quality by 8.2 per cent, as quantified by the global peak-signal-to-noise ratio. These enhanced images allow identification of features that are otherwise hard or impossible to perceive in the original or in filtered/smoothed images with traditional methods. We demonstrate the feasibility of using our deep learning models to enhance XMM-Newton X-ray images to increase their scientific value in a way that could benefit the legacy of the XMM-Newton archive

    Asociación de las dislipidemias con el SNP rs5888 (exón 8) del gen SR-B1

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    Cardiovascular diseases (CVD) are the leading cause of death from non-communicable diseases in the world, with dyslipidemia appearing as a frequent irregularity and main risk factor. The SCARB1 gene encodes the SR-B1 receptor, which is involved in cholesterol clearance and selective HDL uptake. SR-B1 overexpression decreases HDL-C and atherosclerosis, while its absence increases HDL-C and increases atherosclerosis. Aim. To identify the type of association of dyslipidemias with the rs5888 SNP of the SRB1 gene (exon 8) in an apparently healthy population from the state of Morelos, Mexico. Methodology. From a total of 258 samples, DNA was extracted for its purification and quantification, then exon 8 was genotyped using real-time PCR and using the applied biosystems software, genotypic associations (with SNPs and without SNPs) were performed using the Odds Ratio statistical test. Results. 72.87% of the studied population presented dyslipidemia, with hypoαlipoproteinemia being the most frequent, mostly in men (78.19%). A borderline protective association was found for hypoαlipoproteinemia in those with the rs5888 SNP and a risk association for hypercholesterolemia and hypertriglyceridemia, concluding that a change in the same gene may increase or decrease the probability of developing cardiovascular diseases.Las enfermedades cardiovasculares (ECV) son la primera causa de muerte de las enfermedades no transmisibles en el mundo, figurando las dislipidemias como una irregularidad frecuente y principal factor de riesgo. El gen SCARB1 codifica el receptor SR-B1, el cual participa en la depuración del colesterol y captación selectiva de HDL. La sobre expresión del SR-B1 disminuye el HDL-C y la aterosclerosis, mientras que su ausencia incrementa el HDL-C y eleva la aterosclerosis. Objetivo. Identificar el tipo de asociación de las dislipidemias con el SNP rs5888 del gen SRB1 (exón 8) en población aparentemente sana del estado de Morelos México. Metodología. De un total de 258 muestras, se extrajo ADN para su purificación y cuantificación, posteriormente se realizó la genotipificación del exón 8 mediante PCR en tiempo real y utilizando el software applied biosystems, las asociaciones genotípicas (con SNP y sin SNP) se realizaron por la prueba estadística de Razón de Momios. Resultados. El 72.87 % de la población estudiada presenta dislipidemias, siendo la hipoαlipoproteinemia la más frecuente, mayormente en hombres (78.19 %). Se encontró asociación protectora limítrofe para hipoαlipoproteinemia quienes presenten el SNP rs5888 y asociación de riesgo en hipercolesterolemia e hipertrigliceridemia, concluyendo que un cambio en el mismo gen, pueden aumentar o disminuir la probabilidad de desarrollar enfermedades cardiovasculares

    Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}=2.76 TeV

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    The elliptic, v2v_2, triangular, v3v_3, and quadrangular, v4v_4, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions and (anti-)protons in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}} = 2.76 TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range η<0.8|\eta|<0.8 at different collision centralities and as a function of transverse momentum, pTp_{\rm T}, out to pT=20p_{\rm T}=20 GeV/cc. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for pT>8p_{\rm T}>8 GeV/cc. The small pTp_{\rm T} dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to pT=8p_{\rm T}=8 GeV/cc. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least pT=8p_{\rm T}=8 GeV/cc indicating that the particle type dependence persists out to high pTp_{\rm T}.Comment: 16 pages, 5 captioned figures, authors from page 11, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186

    Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm{NN}}} = 2.76 TeV

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    The inclusive transverse momentum (pTp_{\rm T}) distributions of primary charged particles are measured in the pseudo-rapidity range η<0.8|\eta|<0.8 as a function of event centrality in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm{NN}}}=2.76 TeV with ALICE at the LHC. The data are presented in the pTp_{\rm T} range 0.15<pT<500.15<p_{\rm T}<50 GeV/cc for nine centrality intervals from 70-80% to 0-5%. The Pb-Pb spectra are presented in terms of the nuclear modification factor RAAR_{\rm{AA}} using a pp reference spectrum measured at the same collision energy. We observe that the suppression of high-pTp_{\rm T} particles strongly depends on event centrality. In central collisions (0-5%) the yield is most suppressed with RAA0.13R_{\rm{AA}}\approx0.13 at pT=6p_{\rm T}=6-7 GeV/cc. Above pT=7p_{\rm T}=7 GeV/cc, there is a significant rise in the nuclear modification factor, which reaches RAA0.4R_{\rm{AA}} \approx0.4 for pT>30p_{\rm T}>30 GeV/cc. In peripheral collisions (70-80%), the suppression is weaker with RAA0.7R_{\rm{AA}} \approx 0.7 almost independently of pTp_{\rm T}. The measured nuclear modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/284

    Charge separation relative to the reaction plane in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}= 2.76 TeV

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    Measurements of charge dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}} = 2.76 TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudo-rapidity range η<0.8|\eta| < 0.8 are presented as a function of the collision centrality, particle separation in pseudo-rapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge dependent azimuthal correlations observed at RHIC and LHC energies.Comment: 12 pages, 3 captioned figures, authors from page 2 to 6, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/286
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