10,285 research outputs found

    Study of psi' and chi_c decays as feed-down sources of J/psi hadro-production

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    The interpretation of the J/psi suppression patterns observed in nuclear collisions, at CERN and RHIC, as a signature of the formation of a deconfined phase of QCD matter, requires knowing which fractions of the measured J/psi yields, in pp collisions, are due to decays of heavier charmonium states. From a detailed analysis of the available mid-rapidity charmonium hadro-production cross sections, or their ratios, we determine that the J/psi feed-down contributions from psi' and chi_c decays are, respectively, (8.1 +/- 0.3) % and (25 +/- 5) %. These proton-proton values are derived from global averages of the proton-nucleus measurements, assuming that the charmonium states are exponentially absorbed with the length of matter they traverse in the nuclear targets.Comment: 12 pages, 4 figures, 3 table

    Heavy-ion Physics at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC): Feasibility Studies for Quarkonium and Drell-Yan Production

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    We outline the case for heavy-ion-physics studies using the multi-TeV lead LHC beams in the fixed-target mode. After a brief contextual reminder, we detail the possible contributions of AFTER@LHC to heavy-ion physics with a specific emphasis on quarkonia. We then present performance simulations for a selection of observables. These show that Υ(nS)\Upsilon(nS), J/ψJ/\psi and ψ(2S)\psi(2S) production in heavy-ion collisions can be studied in new energy and rapidity domains with the LHCb and ALICE detectors. We also discuss the relevance to analyse the Drell-Yan pair production in asymmetric nucleus-nucleus collisions to study the factorisation of the nuclear modification of partonic densities and of further quarkonia to restore their status of golden probes of the quark-gluon plasma formation.Comment: 18 pages, 7 figure

    A Expressão Global da Doença de Chagas – Oportunidades Emergentes e Impacto em Portugal

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    Chagas disease, caused by the protozoan Trypanosoma cruzi is endemic in the countries of Central and South America. Despite vector control programs and other measures taken in the blood banks and maternity hospitals, it is estimated that there are about eight million people infected worldwide. Although traditionally associated with rural life and poverty, the current migration flows transform it into a global public health problem. In Portugal, this problem is poorly known, with an estimated underdiagnosis index that exceeds 99%. In European countries, besides imported cases, autochthonous infections arise through vertical transmission and blood/organ donation.The conventional serological tests for diagnosing Chagas disease and verifying its cure are indirect hemagglutination (IHA), indirect immunofluorescence (IFAT), and enzyme-linked immunoabsorbent assay (ELISA).The hypothesis of autoimmunity as a basic mechanism of this disease and the absence of early markers of cure are the causes of controversy regarding the specific treatment of this disease. The currently available drugs have adverse effects on a large number of patients and parasitological efficacy in chronic disease is suboptimal.The authors reinforce the need of a high level of suspicion in patients with suggestive epidemiology and the need of populational screening of specific high risk groups

    Clinical study on the melarsoprol-related encephalopathic syndrome: risk factors and HLA association

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    Melarsoprol administration for the treatment of late-stage human African trypanosomiasis (HAT) is associated with the development of an unpredictable and badly characterized encephalopathic syndrome (ES), probably of immune origin, that kills approximately 50% of those affected. We investigated the characteristics and clinical risk factors for ES, as well as the association between the Human Leukocyte Antigen (HLA) complex and the risk for ES in a case-control study. Late-stage Gambiense HAT patients treated with melarsoprol and developing ES (69 cases) were compared to patients not suffering from the syndrome (207 controls). Patients were enrolled in six HAT treatment centres in Angola and in the Democratic Republic of Congo. Standardized clinical data was obtained from all participants before melarsoprol was initiated. Class I (HLA-A, HLA-B, HLA-Cw) and II (HLA-DR) alleles were determined by PCR-SSOP methods in 62 ES cases and 189 controls. The principal ES pattern consisted in convulsions followed by a coma, whereas ES with exclusively mental changes was not observed. Oedema, bone pain, apathy, and a depressed humour were associated with a higher risk of ES, while abdominal pain, coma, respiratory distress, and a Babinski sign were associated with higher ES-associated mortality. Haplotype C*14/B*15 was associated with an elevated risk for ES (OR: 6.64; p-value: 0.008). Haplotypes A*23/C*14, A*23/B*15 and DR*07/B*58 also showed a weaker association with ES. This result supports the hypothesis that a genetically determined peculiar type of immune response confers susceptibility for ES

    The chemistry behind the first Portuguese postage stamps (1853–1894). A non-destructive analytical and chemometric analysis of pigments, fillers and binders

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    The analysis of 28 specimens of some of the first Portuguese postage stamps, dated from 1853 to 1894, was undertaken with non-destructive techniques: X-Ray fluorescence (XRF), Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) and Ultraviolet–Visible Reflectance Spectroscopy (UV–Vis). Ink, paper and cancellation of the postage stamps were analysed, and the pigments, binders and fillers identified. Prussian blue was found present in all blue and also in green and brown specimens. Chrome and zinc yellow, lead sulphate and mars red were also found in other of the investigated postage stamps. Binders consist mostly of protein glue. Fillers such as calcite and kaolinite were found dominant. The presence of the latter served as an indicator for distinguishing between genuine and forged samples. UV–Vis spectra also proved useful for the same purpose. All the above information was processed and organized using chemometric techniques. These include mainly Hierarchical Cluster Analysis (HCA), for clustering stamps of similar composition, and Principal Component Analysis (PCA) for mapping the samples and identifying the more relevant variables. The latter are, in the paper, content of calcium, potassium, sulphur and silicon and, in the dye pigment area, of iron, zinc and lead content. The study introduces an approach in which, by combination of non-destructive multi analytical techniques with chemometric analysis, extensive information on different aspects of the composition of the studied postage stamps is provided, including that of paper and dyes

    Análise da produção brasileira de frutas a partir do armazém de dados da fruticultura.

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    Armazém de dados da fruticultura. Integração dos dados de produção de frutas. Análise da produção brasileira de frutas.bitstream/CNPTIA/9872/1/comuntec18_0.pd

    Intramolecular excimer formation and sensing behavior of new fluorimetric probes and their interactions with metal cations and barbituric acids

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    A new family of compounds able to promote host-guest interactions with specific molecules (e.g., cyanuric and parabanic acids) and to coordinate metal ions, namely Zn(II) and Cu(II), has been synthesized and fully characterized. The new probes derive from the attachment of two methylaminopyrene units to the carbonyl precursor 2,6-bis(2-formylphenoxymethyl)pyridine.http://www.sciencedirect.com/science/article/B6THH-4HF5KD3-1/1/ef66847d1e019d05e2068bef93cfbd9
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