University of Lisbon

About: University of Lisbon is a education organization based out in Lisbon, Lisboa, Portugal. It is known for research contribution in the topics: Population & Context (language use). The organization has 19122 authors who have published 48503 publications receiving 1102623 citations. The organization is also known as: Universidade de Lisboa & Lisbon University.

G0.253 + 0.016: a molecular cloud progenitor of an arches-like cluster

Abstract: Young massive clusters (YMCs) with stellar masses of 104-105 M ☉ and core stellar densities of 104-105 stars per cubic pc are thought to be the "missing link" between open clusters and extreme extragalactic super star clusters and globular clusters. As such, studying the initial conditions of YMCs offers an opportunity to test cluster formation models across the full cluster mass range. G0.253 + 0.016 is an excellent candidate YMC progenitor. We make use of existing multi-wavelength data including recently available far-IR continuum (Herschel/Herschel Infrared Galactic Plane Survey) and mm spectral line (H2O Southern Galactic Plane Survey and Millimetre Astronomy Legacy Team 90 GHz Survey) data and present new, deep, multiple-filter, near-IR (Very Large Telescope/NACO) observations to study G0.253 + 0.016. These data show that G0.253 + 0.016 is a high-mass (1.3 × 105 M ☉), low-temperature (T dust ~ 20 K), high-volume, and column density (n ~ 8 × 104 cm–3;NH2 ~ 4 × 10 23 cm–2) molecular clump which is close to virial equilibrium (M dust ~ M virial) so is likely to be gravitationally bound. It is almost devoid of star formation and, thus, has exactly the properties expected for the initial conditions of a clump that may form an Arches-like massive cluster. We compare the properties of G0.253 + 0.016 to typical Galactic cluster-forming molecular clumps and find it is extreme, and possibly unique in the Galaxy. This uniqueness makes detailed studies of G0.253 + 0.016 extremely important for testing massive cluster formation models.

Relationship between SARS-CoV-2 infection and the incidence of ventilator-associated lower respiratory tract infections: a European multicenter cohort study.

Abstract: Although patients with SARS-CoV-2 infection have several risk factors for ventilator-associated lower respiratory tract infections (VA-LRTI), the reported incidence of hospital-acquired infections is low. We aimed to determine the relationship between SARS-CoV-2 pneumonia, as compared to influenza pneumonia or no viral infection, and the incidence of VA-LRTI. Multicenter retrospective European cohort performed in 36 ICUs. All adult patients receiving invasive mechanical ventilation > 48 h were eligible if they had: SARS-CoV-2 pneumonia, influenza pneumonia, or no viral infection at ICU admission. VA-LRTI, including ventilator-associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP), were diagnosed using clinical, radiological and quantitative microbiological criteria. All VA-LRTI were prospectively identified, and chest-X rays were analyzed by at least two physicians. Cumulative incidence of first episodes of VA-LRTI was estimated using the Kalbfleisch and Prentice method, and compared using Fine-and Gray models. 1576 patients were included (568 in SARS-CoV-2, 482 in influenza, and 526 in no viral infection groups). VA-LRTI incidence was significantly higher in SARS-CoV-2 patients (287, 50.5%), as compared to influenza patients (146, 30.3%, adjusted sub hazard ratio (sHR) 1.60 (95% confidence interval (CI) 1.26 to 2.04)) or patients with no viral infection (133, 25.3%, adjusted sHR 1.7 (95% CI 1.2 to 2.39)). Gram-negative bacilli were responsible for a large proportion (82% to 89.7%) of VA-LRTI, mainly Pseudomonas aeruginosa, Enterobacter spp., and Klebsiella spp. The incidence of VA-LRTI is significantly higher in patients with SARS-CoV-2 infection, as compared to patients with influenza pneumonia, or no viral infection after statistical adjustment, but residual confounding may still play a role in the effect estimates.

Trends in daily rainfall in the Iberian Peninsula from 1951 to 2002

Abstract: An analysis of 22 sites of daily precipitation records over the period 1951–2002 for the Iberian Peninsula is presented. Annual and seasonal total precipitation (P), number of wet days (N), precipitation intensity (I), the 95th percentile (P95), and percentage of rain falling on days with rainfall above the 95th percentile (%) are investigated. The annual and seasonal trends for these variables and for all 22 rain gauges are analysed, using the Mann–Kendall statistic, and a linear regression model. Moreover, a t-test is applied to the difference between the means of two subperiods, respectively 1951–1976 and 1977–2002. Principal results indicate a decreasing trend in P, I, and P95 for several northern and southern stations in winter; P, I, and P95 in some southern stations in spring, I and P95 in some southern stations in summer, and I in some northern and southern stations in autumn. The general behaviour is a decrease in the daily intensity of rainfall, while the number of wet days does not reveal pronounced changes. This pattern is valid for both annual and seasonal values of the indices. The decreasing trend found for I in winter and annual series for some localities may be related to the predominance of the positive phase of the North Atlantic Oscillation (NAO), but it is necessary to find other mechanisms for those stations and seasons not linked directly to NAO. Copyright © 2006 Royal Meteorological Society.

On the mechanism and biology of cytochrome oxidase inhibition by nitric oxide

Abstract: The detailed molecular mechanism for the reversible inhibition of mitochondrial respiration by NO has puzzled investigators: The rate constants for the binding of NO and O2 to the reduced binuclear center CuB/a3 of cytochrome oxidase (COX) are similar, and NO is able to dissociate slowly from this center whereas O2 is kinetically trapped, which altogether seems to favor the complex of COX with O2 over the complex of COX with NO. Paradoxically, the inhibition of COX by NO is observed at high ratios of O2 to NO (in the 40–500 range) and is very fast (seconds or faster). In this work, we used simple mathematical models to investigate this paradox and other important biological questions concerning the inhibition of COX by NO. The results showed that all known features of the inhibition of COX by NO can be accounted for by a direct competition between NO and O2 for the reduced binuclear center CuB/a3 of COX. Besides conciliating apparently contradictory data, this work provided an explanation for the so-called excess capacity of COX by showing that the COX activity found in tissues actually is optimized to avoid an excessive inhibition of mitochondrial respiration by NO, allowing a moderate, but not excessive, overlap between the roles of NO in COX inhibition and in cellular signaling. In pathological situations such as COX-deficiency diseases and chronic inflammation, an excessive inhibition of the mitochondrial respiration is predicted.