820 research outputs found

    Characterization of a defective PbWO4 crystal cut along the a-c crystallographic plane: structural assessment and a novel photoelastic stress analysis

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    Among scintillators, the PWO is one of the most widely used, for instance in CMS calorimeter at CERN and PANDA project. Crystallographic structure and chemical composition as well as residual stress condition, are indicators of homogeneity and good quality of the crystal. In this paper, structural characterization of a defective PbWO4 (PWO) crystal has been performed by X-ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDS) and Photoelasticity in the unusual a-c crystallographic plane. XRD and EDS analysis have been used to investigate crystallographic orientation and chemical composition, while stress distribution, which indicates macroscopic inhomogeneities and defects, has been obtained by photoelastic approaches, in Conoscopic and Sphenoscopic configuration. Since the sample is cut along the a-c crystallographic plane, a new method is proposed for the interpretation of the fringe pattern. The structural analysis has detected odds from the nominal lattice dimension, which can be attributed to the strong presence of Pb and W. A strong inhomogeneity over the crystal sample has been revealed by the photoelastic inspection. The results give reliability to the proposed procedure which is exploitable in crystals with other structures.Comment: 18 pages, 10 figures, revised versio

    THERMAL IMAGING OF ERTA 'ALE LAVA LAKE

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    The project ''Sviluppo di sistemi di monitoraggio'' (Dipartimento di Protezione Civile di Regione Sicilia, INGV Catania Section, Italy), the Leverhulme Trust, the BBC, and the Ethiopian Air Force

    Further constraints on the optical transmission spectrum of HAT-P-1b

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    We report on novel observations of HAT-P-1 aimed at constraining the optical transmission spectrum of the atmosphere of its transiting Hot-Jupiter exoplanet. Ground-based differential spectrophotometry was performed over two transit windows using the DOLORES spectrograph at the Telescopio Nazionale Galileo (TNG). Our measurements imply an average planet to star radius ratio equal to Rp/R\rm R_p/R_{\star}=(0.1159±\pm0.0005). This result is consistent with the value obtained from recent near infrared measurements of this object but differs from previously reported optical measurements being lower by around 4.4 exoplanet scale heights. Analyzing the data over 5 different spectral bins 600\AA\, wide we observed a single peaked spectrum (3.7 σ\rm\sigma level) with a blue cut-off corresponding to the blue edge of the broad absorption wing of sodium and an increased absorption in the region in between 6180-7400\AA. We also infer that the width of the broad absorption wings due to alkali metals is likely narrower than the one implied by solar abundance clear atmospheric models. We interpret the result as evidence that HAT-P-1b has a partially clear atmosphere at optical wavelengths with a more modest contribution from an optical absorber than previously reported.Comment: Accepted by Ap

    The capital accumulation ratio as an indicator of retirement adequacy

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    The relationship between meeting the Capital Accumulation Ratio Guideline and retirement adequacy was investigated. About 63% of the households had a consistent relationship between meeting the 25% ratio guideline and being adequately prepared for retirement, with 46% of households both meeting the 25% ratio guideline and being prepared for retirement and 17% not meeting the guideline and not being adequately prepared for retirement. However, 37% of households did not have a consistent relationship. Meeting the 25% ratio guideline does not appear to be an accurate indicator of retirement adequacy. The 25% guideline was a better indicator than the 50% guideline.Includes bibliographical references

    Factors related to meeting the capital accumulation ratio guideline

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    The capital accumulation ratio, investment assets divided by net worth, has been proposed as a useful indicator of financial health. Various experts recommend a minimum value of 25% to 50% for the ratio. When certificates of deposit are not counted as investment assets, 56% of U.S. households meet the 25% guideline and only 40% meet the 50% guideline. In a multivariate logistic regression, education, income, number of years until retirement, overspending, and financial risk tolerance are positively related to meeting the guidelines.Includes bibliographical references

    Current status of laboratory and imaging diagnosis of neonatal necrotizing enterocolitis

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    Necrotizing enterocolitis continues to be a devastating disease process for very low birth weight infants in Neonatal Intensive Care Units. The aetiology and pathogenesis of necrotizing enterocolitis are not definitively understood. It is known that necrotizing enterocolitis is secondary to a complex interaction of multiple factors that results in mucosal damage, which leads to intestinal ischemia and necrosis. Advances in neonatal care, including resuscitation and ventilation support technology, have seen increased survival rates among premature neonates and a concomitant detection in the incidence of this intestinal disease.Diagnosis can be difficult, and identifying infants at the onset of disease remains a challenge. Early diagnosis, which relies on imaging findings, and initiation of prompt therapy are essential to limit morbidity and mortality. Moreover, early management is critical and life-saving.This review summarizes what is known on the laboratory and instrumental diagnostic strategies needed to improve neonatal outcomes and, possibily, to prevent the onset of an overt necrotizing enterocolitis
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