3,281 research outputs found

    increased endothelin 1 mediated vasoconstrictor tone in human obesity effects of gut hormones

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    The heavy impact of obesity on the development and progression of cardiovascular disease has sparked sustained efforts to uncover the mechanisms linking excess adiposity to vascular dysfunction. Impaired vasodilator reactivity has been recognized as an early hemodynamic abnormality in obese patients, but also increased vasoconstrictor tone importantly contributes to their vascular damage. In particular, upregulation of the endothelin (ET)-1 system, consistently reported in these patients, might accelerate atherosclerosis and its complication, given the pro-inflammatory and mitogenic properties of ET-1. In recent years, a number of gut hormones, in addition to their role as modulators of food intake, energy balance, glucose and lipid metabolism, and insulin secretion and action, have demonstrated favorable vascular actions. They increase the bioavailability of vasodilator mediators like nitric oxide, but they have also been shown to inhibit the ET-1 system. These features make gut hormones promising tools for targeting both the metabolic and cardiovascular complications of obesity, a view supported by recent large-scale clinical trials indicating that novel drugs for type 2 diabetes with cardiovascular potential may translate into clinically significant advantages. Therefore, there is real hope that better understanding of the properties of gut-derived substances might provide more effective therapies for the obesity-related cardiometabolic syndrome

    Correlating densities of centrality and activities in cities : the cases of Bologna (IT) and Barcelona (ES)

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    This paper examines the relationship between street centrality and densities of commercial and service activities in cities. The aim is to verify whether a correlation exists and whether some 'secondary' activities, i.e. those scarcely specialized oriented to the general public and ordinary daily life, are more linked to street centrality than others. The metropolitan area of Barcelona (Spain) is investigated, and results are compared with those found in a previous work on the city of Bologna (Italy). Street centrality is calibrated in a multiple centrality assessment (MCA) model composed of multiple measures such as closeness, betweenness and straightness. Kernel density estimation (KDE) is used to transform data sets of centrality and activities to one scale unit for correlation analysis between them. Results indicate that retail and service activities in both Bologna and Barcelona tend to concentrate in areas with better centralities, and that secondary activities exhibit a higher correlation

    Post-fire management of cork oak forests

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    28 pĂĄginas, 11 figuras.This chapter concerns the ecology and post-fire management of cork oak forests. It starts with a short overview of ecological and socio-economic context, continuing with an introduction on the cork oak post-fire regeneration strategies and the main factors affecting tree responses. Several post-fire management issues and alternatives, such as tree logging, assisting natural regeneration, reforestation, cork harvesting and pruning, or protecting against herbivory, are also presented and discussed.To all people who contributed in some way to the contents of this chapter, with special thanks to Francisco Rego, Paulo Fernandes and Thomas Curt. To Fundação para a CiĂȘncia e a Tecnologia (PhD grant SFRH/BD/65991/2009), FFP (project Recuperação de Áreas Ardidas), EU (COST FP0701 and TRANZFOR), and the Spanish government (project VARQUS, CGL2004-4325/BOS).Peer reviewe

    Discovery of the supernova remnant G351.0-5.4

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    Context. While searching the NRAO VLA Sky Survey (NVSS) for diffuse radio emission, we have serendipitously discovered extended radio emission close to the Galactic plane. The radio morphology suggests the presence of a previously unknown Galactic supernova remnant. An unclassified {\gamma}-ray source detected by EGRET (3EG J1744-3934) is present in the same location and may stem from the interaction between high-speed particles escaping the remnant and the surrounding interstellar medium. Aims. Our aim is to confirm the presence of a previously unknown supernova remnant and to determine a possible association with the {\gamma}-ray emission 3EG J1744-3934. Methods. We have conducted optical and radio follow-ups of the target using the Dark Energy Camera (DECam) on the Blanco telescope at Cerro Tololo Inter-American Observatory (CTIO) and the Giant Meterwave Radio Telescope (GMRT). We then combined these data with archival radio and {\gamma}-ray observations. Results. While we detected the extended emission in four different radio bands (325, 1400, 2417, and 4850 MHz), no optical counterpart has been identified. Given its morphology and brightness, it is likely that the radio emission is caused by an old supernova remnant no longer visible in the optical band. Although an unclassified EGRET source is co-located with the supernova remnant, Fermi-LAT data do not show a significant {\gamma}-ray excess that is correlated with the radio emission. However, in the radial distribution of the {\gamma}-ray events, a spatially extended feature is related with SNR at a confidence level ∌1.5\sim 1.5 {\sigma}. Conclusions. We classify the newly discovered extended emission in the radio band as the old remnant of a previously unknown Galactic supernova: SNR G351.0-5.4.Comment: 6 pages, 6 figures, accepted A&

    Development of an Equilibrium-based Model of Gasification of Biomass by Aspen Plus

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    Abstract Agricultural and forestry residues are usually processed as wastes; otherwise, they can be recovered to produce electrical and thermal energy through processes of thermochemical conversion, such us torrefaction, pyrolysis and gasification. Currently, the gasification of residual biomass for producing neutral CO 2 fuel for energy production is in development stage. In this context, this study proposes anequilibrium-based model, developed by the commercial software Aspen Plus, of a co-current gasifier fueled with agriculture residual, which allows estimating the chemical composition and theheating value of the syngas produced. The prediction of such model includes the main gaseous species, the yields of char and tar and describes the gasification process through the mass and energy balances, the water-gas shift (WGS) and the methanation reaction. The model validation was carried out through the comparison with experimental data, concerning two biomass with different moisture content and different gasification conditions, for sixteen cases compared. Overall, the comparison between the results of the simulations and the experimental data have shown a good agreement

    Calibration of a Multichannel Water Vapor Raman Lidar through Noncollocated Operational Soundings: Optimization and Characterization of Accuracy and Variability

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    Abstract This paper presents a parametric automatic procedure to calibrate the multichannel Rayleigh–Mie–Raman lidar at the Institute for Atmospheric Science and Climate of the Italian National Research Council (ISAC-CNR) in Tor Vergata, Rome, Italy, using as a reference the operational 0000 UTC soundings at the WMO station 16245 (Pratica di Mare) located about 25 km southwest of the lidar site. The procedure, which is applied to both channels of the system, first identifies portions of the lidar and radiosonde profiles that are assumed to sample the same features of the water vapor profile, taking into account the different time and space sampling. Then, it computes the calibration coefficient with a best-fit procedure, weighted by the instrumental errors of both radiosounding and lidar. The parameters to be set in the procedure are described, and values adopted are discussed. The procedure was applied to a set of 57 sessions of nighttime 1-min-sampling lidar profiles (roughly about 300 h of measurements) covering the whole annual cycle (February 2007–September 2008). A calibration coefficient is computed for each measurement session. The variability of the calibration coefficients (∌10%) over periods with the same instrumental setting is reduced compared to the values obtained with the previously adopted, operator-assisted, and time-consuming calibration procedure. Reduction of variability, as well as the absence of evident trends, gives confidence both on system stability as well as on the developed procedure. Because of the definition of the calibration coefficient and of the different sampling between lidar and radiosonde, a contribution to the variability resulting from aerosol extinction and to the spatial and temporal variability of the water vapor mixing ratio is expected. A preliminary analysis aimed at identifying the contribution to the variability from these factors is presented. The parametric nature of the procedure makes it suitable for application to similar Raman lidar systems

    Evolutionary vaccination dilemma in complex networks

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    In this work we analyze the evolution of voluntary vaccination in networked populations by entangling the spreading dynamics of an influenza-like disease with an evolutionary framework taking place at the end of each influenza season so that individuals take or do not take the vaccine upon their previous experience. Our framework thus puts in competition two well-known dynamical properties of scale-free networks: the fast propagation of diseases and the promotion of cooperative behaviors. Our results show that when vaccine is perfect, scale-free networks enhance the vaccination behavior with respect to random graphs with homogeneous connectivity patterns. However, when imperfection appears we find a crossover effect so that the number of infected (vaccinated) individuals increases (decreases) with respect to homogeneous networks, thus showing the competition between the aforementioned properties of scale-free graphs