192 research outputs found

    Effect of the alien invasive bivalve Corbicula fluminea on the nutrient dynamics under climate change scenarios

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    The main aim of this study was to evaluate the impact of the alien invasive bivalve Corbicula fluminea (Müller, 1774) in the nutrient dynamics of temperate estuarine systems (oligohaline areas) under climate change scenarios. The scenarios simulated shifts in climatic conditions, following salinity (0 or 5) and temperature (24 or 30 °C) changes, usual during drought and heat wave events. The effect of the individual size/age (different size classes with fixed biomass) and density (various densities of <1 cm clams) on the bioturbation-associated nutrient dynamics were also evaluated under an 18-day laboratory experimental setup. Results highlight the significant effect of C. fluminea on the ecosystem nutrient dynamics, enhancing the efflux of both phosphate and dissolved inorganic nitrogen (DIN) from the sediments to the water column. Both drought and heat wave events will have an impact on the DIN dynamics within C. fluminea colonized systems, favouring a higher NH4-N efflux. The population structure of C. fluminea will have a decisive role on the impact of the species, with stronger nutrient effluxes associated with a predominantly juvenile population structure.publishe

    Sensing cloud optimization to solve ED of units with valve-point effects and multi-fuels

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    In this paper a solution to an highly constrained and non-convex economical dispatch (ED) problem with a meta-heuristic technique named Sensing Cloud Optimization (SCO) is presented. The proposed meta-heuristic is based on a cloud of particles whose central point represents the objective function value and the remaining particles act as sensors "to fill" the search space and "guide" the central particle so it moves into the best direction. To demonstrate its performance, a case study with multi-fuel units and valve- point effects is presented

    Phase transitions for suspension flows

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    This paper is devoted to study thermodynamic formalism for suspension flows defined over countable alphabets. We are mostly interested in the regularity properties of the pressure function. We establish conditions for the pressure function to be real analytic or to exhibit a phase transition. We also construct an example of a potential for which the pressure has countably many phase transitions.Comment: Example 5.2 expanded. Typos corrected. Section 6.1 superced the note "Thermodynamic formalism for the positive geodesic flow on the modular surface" arXiv:1009.462

    Green manure in coffee systems in the region of Zona da Mata, Minas Gerais: characteristics and kinetics of carbon and nitrogen mineralization.

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    The use of green manure may contribute to reduce soil erosion and increase the soil organic matter content and N availability in coffee plantations in the Zona da Mata, State of Minas Gerais, in Southeastern Brazil. The potential of four legumes (A. pintoi, C. mucunoides, S. aterrimum and S. guianensis)to produce above-ground biomass, accumulate nutrients and mineralize N was studied in two coffee plantations of subsistence farmers under different climate conditions. The biomass production of C. mucunoides was influenced by the shade of the coffee plantation.C. mucunoides tended to mineralize more N than the other legumes due to the low polyphenol content and polyphenol/N ratio. In the first year, the crop establishment of A. pintoi in the area took longer than of the other legumes, resulting in lower biomass production and N2 fixation. In the long term, cellulose was the main factor controlling N mineralization. The biochemical characteristics, nutrient accumulation and biomass production of the legumes were greatly influenced by the altitude and position of the area relative to the sun

    Potentially inappropriate medication use among institutionalized elderly individuals in southeastern Brazil

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    In recent decades, the elderly population in Brazil has grown rapidly, as has concern for the health of this population. Institutionalization in nursing homes has appeared as an alternative form of health care for frail elderly that live alone. The present study evaluated the pharmacotherapy and inappropriate drug prescriptions for institutionalized elderly patients living in long-term institutions in southeastern Brazil. This research was conducted at five institutions with a total sample of 151 individuals aged at least 60 years. Databases were used to identify drug interactions, defined daily dose and inappropriate prescriptions. The prevalence of drug intake among the elderly was 95.36%, and there were an average of 3.31 ± 1.80 drug prescriptions per individual. Based on Beers criteria, the prevalence of inappropriate prescriptions was 25.83%. In addition, 70.2% of prescriptions were prescribed at a higher dosage than the defined daily dose (ATC/WHO). Potential drug interactions were identified for 54.11% of prescriptions; 81.42% of these were of moderate severity. The main inappropriate drugs were prescribed for cardiovascular and nervous system problems. Institutionalized elderly individuals presented a high consumption and misuse of medications, requiring professional intervention to monitor prescriptions and improve the quality of service for this population
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