1,187 research outputs found

    Numerical modelling of the dynamic response of liquefiable deposits in the presence of small scale buildings

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    The impact of liquefaction in building performance during earthquakes is an aspect that has been recently receiving more attention by the technical and scientific communities, in an attempt to reduce the vulnerability of structures located in loose sandy saturated deposits. Currently, the design of buildings in liquefiable layers is performed based on empirical rules, where the liquefaction potential and the ground settlements are usually assessed free-field conditions, i.e., neglecting the presence of the surface structures. Even in the probabilistic approaches that tend to incorporate Earthquake Liquefaction Induced Damages (ELID) from some case-histories that include buildings at the surface, have never incorporated foundations characteristics and loading conditions. However, recent advances in numerical modelling allow performing a more rigorous assessment of the effects induced by liquefaction, namely the settlements that are expected to occur in the spread footings of structures, one of the most common foundation system implemented in small-to-mid-rise constructions in Europe. Therefore, the present paper focuses research on the assessment of the settlements due to earthquake-induced liquefaction that is being conducted within the European Project LIQUEFACT

    Ectopia cordis: caso clĂ­nico

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    Introduction: ectopia cordis is a rare congenital malformation, with an estimated incidence of 5 to 8 per million live births. It is defined as a malformation in which the heart is located in an extra-thoracic position. Ectopia cordis may occur as an isolated malformation or associated with other anomalies such as omphalocele, congenital heart disease or integrating Cantrell syndrome. The size and location of the defect influence the prognosis. Description: we report a case of a 24-year-old nulliparous woman, with no relevant family or personal history, in which the prenatal fetal ultrasound, performed at 21 weeks of gestation, revealed a defect of the anterior chest wall with exteriorization of the heart. Discussion: fetal echocardiography revealed a severe congenital heart disease. The parents decided to continue the pregnancy, after being duly informed by a multidisciplinary team. Delivery occurred at 37 weeks of gestation but the female newborn died one hour afterwards. Pathological examination confirmed the sonographic findings

    Dose-dependent effects of Allopurinol on human foreskin fibroblast cell and human umbilical vein endothelial cell under hypoxia

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    Allopurinol, an inhibitor of xanthine oxidase, has been used in clinical trials of patients with cardiovascular and chronic kidney disease. These are two pathologies with extensive links to hypoxia and activation of the transcription factor hypoxia inducible factor (HIF) family. Here we analysed the effects of allopurinol treatment in two different cellular models, and their response to hypoxia. We explored the dose-dependent effect of allopurinol on Human Foreskin Fibroblasts (HFF) and Human Umbilical Vein Endothelial Cells (HUVEC) under hypoxia and normoxia. Under normoxia and hypoxia, high dose allopurinol reduced the accumulation of HIF-1Îą protein in HFF and HUVEC cells. Allopurinol had only marginal effects on HIF-1Îą mRNA level in both cellular systems. Interestingly, allopurinol effects over the HIF system were independent of prolyl-hydroxylase activity. Finally, allopurinol treatment reduced angiogenesis traits in HUVEC cells in an in vitro model. Taken together these results indicate that high doses of allopurinol inhibits the HIF system and pro-angiogenic traits in cells

    Prognostic Value of Isolated Elevated Troponin I Levels in Patients without Acute Coronary Syndrome Admitted to the Emergency Department

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    Background: Although non-ischemic troponin elevation is frequently seen in patients admitted to the emergency department (ED), consensus regarding its management is lacking. Objectives: This study aimed to characterize patients admitted to the ED with non-ischemic troponin elevation and to identify potential mortality predictors in this population. Methods: This retrospective observational study included ED patients with a positive troponin test result between June and July of 2015. Patients with a clinical diagnosis of acute coronary syndrome (ACS) were excluded. Data on patient demographics and clinical and laboratory variables were extracted from medical records. Follow-up data were obtained for 16 months or until death occurred. The statistical significance level was 5%. Results: Troponin elevation without ACS was found in 153 ED patients. The median (IQR) patient age was 78 (19) years, 80 (52.3%) were female and 59(38.6%) died during follow-up. The median (IQR) follow-up period was 477(316) days. Survivors were significantly younger 76 (24) vs. 84 (13) years; p=0.004) and featured a higher proportion of isolated troponin elevation (without creatine kinase or myoglobin elevation) in two consecutive evaluations: 48 (53.9%) vs. 8 (17.4%), p<0.001. Survivors also presented a lower rate of antiplatelet treatment and same-day hospitalization. In the multivariate logistic regression with adjustment for significant variables in the univariate analysis, isolated troponin elevation in two consecutive evaluations showed a hazard ratio= 0.43 (95%CI 0.17-0.96, p=0.039); hospitalization, previous antiplatelet treatment and age remained independently associated with mortality. Conclusions: Isolated troponin elevation in two consecutive measurements was a strong predictor of survival in ED patients with troponin elevation but without ACS.info:eu-repo/semantics/publishedVersio

    Segregation trends of the metal alloys Mo-Re and Mo-Pt on HfO2: A first-principles study

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    Using first-principles calculations, we compared the segregation trends at the surface of metal alloys with those at an interface with HfO2. The choice of this oxide was motivated by its significance as a potential replacement for SiO2 in advanced transistors. We considered Mo-Re and Mo-Pt alloys as typical examples of disordered and ordered alloys, respectively. The segregation to the surface/interface was analyzed in terms of metal and oxygen adsorption energies. It is shown that chemical bonding at the metal/oxide interface strongly influences segregation both in Mo-Re and Mo-Pt alloys. In particular, bonding with oxygen atoms at the oxide/Mo-Re alloy interface depletes the Re content of the interfacial layer. In the case of Mo-Pt on HfO2 an oxygen-rich interface promotes the formation of one monolayer (but not two monolayers) of Mo separating PtMox from HfO2, while a stoichiometric interface favors an abrupt PtMox/HfO2 interface. This study also shows that the presence of Mo in the alloy stabilizes Pt which can potentially decrease the tendency of Pt to diffuse into the oxide matrix. The individual constituents of these intermetallic compounds exhibit high vacuum work functions, and therefore these alloys are also likely to have sufficiently high work functions to be considered as promising candidates for p-type gate electrodes in future generations of transistors. (c) 2006 American Institute of Physics.100

    Influence of packing density and stress on the dynamic response of granular materials

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    Laboratory geophysics tests including bender elements and acoustic emission measure the speed of propagation of stress or sound waves in granular materials to derive elastic stiffness parameters. This contribution builds on earlier studies to assess whether the received signal characteristics can provide additional information about either the material’s behaviour or the nature of the material itself. Specifically it considers the maximum frequency that the material can transmit; it also assesses whether there is a simple link between the spectrum of the received signal and the natural frequencies of the sample. Discrete element method (DEM) simulations of planar compression wave propagation were performed to generate the data for the study. Restricting consideration to uniform (monodisperse) spheres, the material fabric was varied by considering face-centred cubic lattice packings as well as random configurations with different packing densities. Supplemental analyses, in addition to the DEM simulations, were used to develop a more comprehensive understanding of the system dynamics. The assembly stiffness and mass matrices were extracted from the DEM model and these data were used in an eigenmode analysis that provided significant insight into the observed overall dynamic response. The close agreement of the wave velocities estimated using eigenmode analysis with the DEM results confirms that DEM wave propagation simulations can reliably be used to extract material stiffness data. The data show that increasing either stress or density allows higher frequencies to propagate through the media, but the low-pass wavelength is a function of packing density rather than stress level. Prior research which had hypothesised that there is a simple link between the spectrum of the received signal and the natural sample frequencies was not substantiated

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

    Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

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    The azimuthal anisotropy of charged particles in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (pt) range up to approximately 60 GeV. The data cover both the low-pt region associated with hydrodynamic flow phenomena and the high-pt region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v2 values are found to first increase with pt, reaching a maximum around pt = 3 GeV, and then to gradually decrease to almost zero, with the decline persisting up to at least pt = 40 GeV over the full centrality range measured.Comment: Replaced with published version. Added journal reference and DO
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