487 research outputs found

    An efficient multi-objective evolutionary approach for solving the operation of multi-reservoir system scheduling in hydro-power plants

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    This paper tackles the short-term hydro-power unit commitment problem in a multi-reservoir system ? a cascade-based operation scenario. For this, we propose a new mathematical modeling in which the goal is to maximize the total energy production of the hydro-power plant in a sub-daily operation, and, simultaneously, to maximize the total water content (volume) of reservoirs. For solving the problem, we discuss the Multi-objective Evolutionary Swarm Hybridization (MESH) algorithm, a recently proposed multi-objective swarm intelligence-based optimization method which has obtained very competitive results when compared to existing evolutionary algorithms in specific applications. The MESH approach has been applied to find the optimal water discharge and the power produced at the maximum reservoir volume for all possible combinations of turbines in a hydro-power plant. The performance of MESH has been compared with that of well-known evolutionary approaches such as NSGA-II, NSGA-III, SPEA2, and MOEA/D in a realistic problem considering data from a hydro-power energy system with two cascaded hydro-power plants in Brazil. Results indicate that MESH showed a superior performance than alternative multi-objective approaches in terms of efficiency and accuracy, providing a profit of $412,500 per month in a projection analysis carried out.European CommissionMinisterio de Economía y CompetitividadComunidad de Madri

    An efficient multi-objective evolutionary approach for solving the operation of multi-reservoir system scheduling in hydro-power plants

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    This paper tackles the short-term hydro-power unit commitment problem in a multi-reservoir system ? a cascade-based operation scenario. For this, we propose a new mathematical modeling in which the goal is to maximize the total energy production of the hydro-power plant in a sub-daily operation, and, simultaneously, to maximize the total water content (volume) of reservoirs. For solving the problem, we discuss the Multi-objective Evolutionary Swarm Hybridization (MESH) algorithm, a recently proposed multi-objective swarm intelligence-based optimization method which has obtained very competitive results when compared to existing evolutionary algorithms in specific applications. The MESH approach has been applied to find the optimal water discharge and the power produced at the maximum reservoir volume for all possible combinations of turbines in a hydro-power plant. The performance of MESH has been compared with that of well-known evolutionary approaches such as NSGA-II, NSGA-III, SPEA2, and MOEA/D in a realistic problem considering data from a hydro-power energy system with two cascaded hydro-power plants in Brazil. Results indicate that MESH showed a superior performance than alternative multi-objective approaches in terms of efficiency and accuracy, providing a profit of $412,500 per month in a projection analysis carried out.European CommissionAgencia Estatal de InvestigaciónComunidad de Madri

    Structural glass on a lattice in the limit of infinite dimensions

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    We construct a mean field theory for the lattice model of a structural glass and solve it using the replica method and one step replica symmetry breaking ansatz; this theory becomes exact in the limit of infinite dimensions. Analyzing stability of this solution we conclude that the metastable states remain uncorrelated in a finite temperature range below the transition, but become correlated at sufficiently low temperature. We find dynamic and thermodynamic transition temperatures as functions of the density and construct a full thermodynamic description of a typical physical process in which the system gets trapped in one metastable state when cooled below vitrification temperature. We find that for such physical process the entropy and pressure at the glass transition are continuous across the transition while their temperature derivatives have jumps.Comment: 4 pages, 2 figure

    A poorer nutritional status impacts quality of life in a sample population of elderly cancer patients

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    Rationale Quality of Life (QoL) is impaired in cancer, and the elderly are particularly vulnerable to malnutrition. A diagnosis of cancer in elderly patients further exacerbates risks of negative health outcomes. Here we investigated associations between QoL and nutritional status in a sample population of mostly socially deprived elderly cancer patients. Method 432 cancer patients were recruited for this cross-sectional study at point of admission to a tertiary referral hospital for cancer treatment. Patient-generated subjective global assessment (PG-SGA) assessed nutritional status. Functional assessment of cancer therapy- general (FACT-G) quantified QoL. Relationship between PG-SGA and QoL was assessed by Spearman correlation. PG-SGA outcomes were compared against FACT-G scores employing Mann–Whitney test. Bivariate Linear Regression Model was employed to investigate influences of sociodemographic, clinical and nutritional status upon QoL. Results 37.5% of participants were malnourished or at risk. 39% were illiterate and 54.6% had family income lower than minimum wage. Malnourished patients showed lower FACT-G scores (76.8 vs. 84.7; p = 0.000). Poor nutritional diagnosis was inversely correlated with all QoL domains. Bivariate regression analysis showed that lower PG-SGA scores (βo =  − 1.00; p = 0.000) contributed to FACT-G score deterioration, the male gender showed better QoL scores, and other clinical and sociodemographic variables did not show relationship. Conclusion Poorer nutritional status was significantly associated with worsened physical, social, emotional and functional well-being QoL domains in elderly cancer patients. Poorer nutritional status is an independent risk factor for worsened QoL. Future policies aimed at particularly vulnerable populations may improve QoL and health outcomes

    Wobbly syndrome in an african pygmy hedgehog (Atelerix albiventris) : Neuropathological and immunohistochemical studies Síndrome de wobbly em um ouriço pigmeu africano (Atelerix albiventris): estudo neuropatológico e imuno-histoquímico

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    Scholarships were provided by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) - Finance Code 001. Additional support was provided by Pró-Reitoria de Pesquisa da Universidade Federal de Minas Gerais (UFMG).A three-year-old female African pygmy hedgehog (Atelerix albiventris), born and domiciled in Brazil, presented apathy, prostration, and difficulty to stay standing. Its parents were siblings but did not present clinical signs related to this condition. As its clinical condition worsened, the animal was euthanized and referred for necropsy. No gross lesions were found in the central nervous system (CNS). Histologically, there was vacuolation with axonal degeneration in the white matter of the CNS and in peripheral nervous tissue. The Kluver-Barrera (KB) stain confirmed demyelination in vacuolated areas. Immunohistochemistry using several neural markers confirmed astrocytosis and microgliosis associated with vacuolated areas. In addition, there was a mild decrease in the immuno intensity of myelin proteolipid protein (PLP) in these areas. These results suggest a genetic origin of the present demyelination, which resulted in the wobbly syndrome described in this report

    Chemoenzymatic synthesis of (S)-Pindolol using lipases

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    A straightforward chemoenzymatic synthesis of (S)-Pindolol has been developed. The key step involved the enzymatic kinetic resolution of rac-2-acetoxy-1-(1H-indol-4-yloxy)-3-chloropropane with lipase from Pseudomonas fluorescens via hydrolytic process to obtain enantiomerically enriched halohydrin (2S)-1-(1H-indol-4-yloxy)-3-chloro-2-propanol (96% ee) and (2R)-2-acetoxy-1-(1H-indol-4-yloxy)-3-chloropropane (97% ee). The latter was subjected to a hydrolysis reaction catalyzed by Candida rugosa leading to (2R)-1-(1H-indol-4-yloxy)-3-chloro-2-propanol (97% ee), followed by a reaction with isopropylamine, producing (S)-Pindolol (97% ee) in quantitative yield

    Metastable States in Spin Glasses and Disordered Ferromagnets

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    We study analytically M-spin-flip stable states in disordered short-ranged Ising models (spin glasses and ferromagnets) in all dimensions and for all M. Our approach is primarily dynamical and is based on the convergence of a zero-temperature dynamical process with flips of lattice animals up to size M and starting from a deep quench, to a metastable limit. The results (rigorous and nonrigorous, in infinite and finite volumes) concern many aspects of metastable states: their numbers, basins of attraction, energy densities, overlaps, remanent magnetizations and relations to thermodynamic states. For example, we show that their overlap distribution is a delta-function at zero. We also define a dynamics for M=infinity, which provides a potential tool for investigating ground state structure.Comment: 34 pages (LaTeX); to appear in Physical Review
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