4,002 research outputs found

    SAMBA: Stochastic Analytical Model with a Bayesian Approach

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    We develop and estimate a DSGE model for the Brazilian economy, to be used as part of the macroeconomic modeling framework at the Central Bank of Brazil. The model combines the building blocks of standard DSGE models (e.g., price and wage rigidities and adjustment costs) with the following features that better describe the Brazilian economy: (i) a fiscal authority pursuing an explicit target for the primary surplus; (ii) administered or regulated prices as part of consumer prices; (iii) external finance for imports, amplifying the effects of changes in external financial conditions on the economy; and (iv) imported goods used in the production function of differentiated goods. It also includes the presence of financially constrained households. We estimate the model with Bayesian techniques, using data starting in 1999, when inflation targeting was implemented. Model evaluation, based on impulse response functions, moment conditions, variance error decomposition and initial forecasting exercises, suggests that the model can be a useful tool for policy analysis and forecasting.

    Soil water distribution for subsurface and surface drip irrigation

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    Devido à falta de estudos sobre o movimento da água quando aplicada abaixo da superfície, realizou-se este trabalho com o objetivo de avaliar a distribuição de água aplicada pelo sistema de gotejamento enterrado e convencional. O experimento de campo foi conduzido na área experimental do Departamento de Engenharia Rural da ESALQ/USP - Piracicaba, SP. Para o estudo, trincheiras foram abertas e instaladas sondas de TDR, dispostas a 0,05; 0,15; 0,25; 0,35 e 0,45 m profundidade, e a 0,05; 0,15; 0,25; 0,35 m comprimento, totalizando 17 sondas por trincheira. Os tratamentos foram baseados na profundidade de aplicação (0,0 e 0,10 m) e vazão aplicada (2 e 4 L h-1): ENT2; ENT4; SUP2 e SUP4. A cada hora era aplicado 1 L de água (total de 10 L), seguida de leituras com o TDR. Medições do disco úmido e saturado foram feitas com régua milimetrada; além disso, estabeleceu-se um volume controle onde foi avaliada a uniformidade de aplicação; assim, foi possível verificar, em relação aos sistemas superficiais, que os sistemas enterrados apresentaram menor área superficial molhada e atingiram maior largura e profundidade; já as maiores concentrações foram obtidas próximas ao ponto de emissão.Studies of sub-surface water movement is an interesting topic in irrigation but, in spite of the its importance, there is little literature. One of the purposes of this study was to contribute to this subject and evaluate the distribution of water applied by both subsurface drip irrigation (SDI) and conventional irrigation. Experiments were conducted at the Department of Rural Engineering (ESALQ/USP), located at Piracicaba, SP. Trenches were opened and 17 three-rod TDR probes were installed, placed at 0.05, 0.15, 0.25, 0.35 and 0.45 m depths, and to 0.05, 0.15, 0.25, 0.35 m intervals. This procedure was repeated using a dripper buried at 0 and 0.10 m for each discharge rate of 2 and 4 L h-1 tested. Wetted soil volume was observed with 1 L of water applications at intervals (total 10 L). The saturated disc around the dripper and the advance of the wetting front on the soil surface were measured with a ruler. Also, a central control volume was established inside the wetted soil volume where the uniformity of application was evaluated. The results suggest that SDI presented smaller wetted soil surface area and it reached larger distance and depth with greater storage of solution adjacent to the dripper

    Trophic control in the Guadalquivir estuary and neighbouring waters of the Gulf of Cadiz

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    The Guadalquivir estuary (SW Spain) is a non-stratified estuary with a gradual change in salinity. It supports an important biodiversity and functions as a nursery area for many commercial species (e.g. anchovy) in the Gulf of Cadiz (GoC). The understanding of the interplay between the environmental forcing (bottom-up) and the trophic regulation is essential to understand its functioning in relation to the GoC fisheries. Here, we seek to study the effects of environmental variables and predator-prey interaction (mysid-anchovy) in the estuary and surrounding marine areas with a particular focus on the zooplankton as key intermediaries between primary production and marine fish juveniles. A long-term (18 yr) monitoring program has been carried out in two sites: Tarfia and Bonanza (32 km and 8 km distance from the river mouth respectively). The latter station samples well the marine water masses advected into the estuary during the ebb flow. Our dataset includes mysids, anchovy larvae and juveniles, temperature, salinity, turbidity, freshwater discharges, precipitation and winds. We used time series-analysis (GAMs) to test the trophic, environmental and anthropogenic effects. Temperature was found to have a positive effect on mysids at both stations while salinity showed a positive effect only at Tarfia. Turbidity showed a strong negative effect on the whole estuary and so did the freshwater discharges at Bonanza, which are regulated by a dam. The results indicate that the trophic control in the estuary of the Guadalquivir is resource-driven. Our models also highlight that marine mysids have a positive effect on anchovy

    Essential role of the czc determinant for cadmium, cobalt and zinc resistance in Gluconacetobacter diazotrophicus PAl 5

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    The mechanisms of cadmium, cobalt and zinc resistance were characterized in the plant-growth-promoting bacterium Gluconacetobacter diazotrophicus PAl 5. The resistance level of the wild-type strain was evaluated through the establishment of minimum inhibitory concentrations (MIC) of the soluble compounds CdCl2·H2O, CoCl2·6H2O and ZnCl2. Gluconacetobacter diazotrophicus PAl 5 was resistant to high concentrations of Cd, Co and Zn, with MICs of 1.2, 20 and 20 mM, respectively. Screening of an insertion library from transposon EZ-Tn5<R6Kyori/KAN-2> in the presence of ZnO revealed that the mutant GDP30H3 was unable to grow in the presence of the compound. This mutant was also highly sensitive to CdCl2·H2O, CoCl2·6H2O and ZnCl2. Molecular characterization established that the mutation affected the czcA gene, which encodes a protein involved in metal efflux. In silico analysis showed that czcA is a component of the czcCBARS operon together with four other genes. This work provides evidence of the high tolerance of G. diazotrophicus PAl 5 to heavy metalsand that czc is a determinant for metal resistance in this bacterium. [Int Microbiol 2012; 15(2):69-78

    Load Index Metrics for an Optimized Management of Web Services: A Systematic Evaluation

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    The lack of precision to predict service performance through load indices may lead to wrong decisions regarding the use of web services, compromising service performance and raising platform cost unnecessarily. This paper presents experimental studies to qualify the behaviour of load indices in the web service context. The experiments consider three services that generate controlled and significant server demands, four levels of workload for each service and six distinct execution scenarios. The evaluation considers three relevant perspectives: the capability for representing recent workloads, the capability for predicting near-future performance and finally stability. Eight different load indices were analysed, including the JMX Average Time index (proposed in this paper) specifically designed to address the limitations of the other indices. A systematic approach is applied to evaluate the different load indices, considering a multiple linear regression model based on the stepwise-AIC method. The results show that the load indices studied represent the workload to some extent; however, in contrast to expectations, most of them do not exhibit a coherent correlation with service performance and this can result in stability problems. The JMX Average Time index is an exception, showing a stable behaviour which is tightly-coupled to the service runtime for all executions. Load indices are used to predict the service runtime and therefore their inappropriate use can lead to decisions that will impact negatively on both service performance and execution cost

    Seasonal variation of zooplankton and environmental conditions along a transect in the Gulf of Cádiz

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    This study presents seasonal variation in the zooplankton composition of the Gulf of Cádiz was studied between 2001 and 2012. Samples were collected three times per year, in the spring, summer and autumn at three stations situated along a transect perpendicular to the coast. The total zooplankton abundance during the summer was higher than in the spring and autumn. Zooplankton community is characterized by a seasonal cycle mirroring similar cycles in the physical environment. Differences in community composition were also found along the transect, particularly between the coastal station, under the influence of the Guadalquivir River, and the outer station, characterized by oceanic conditions. This study is the first description of the seasonal and spatial variation of this marine component of the Gulf of Cádi

    Recovery and partitioning of fibrinolytic protease from Bacillus sp. UFPEDA 485 by aqueous two-phase systems

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    Fibrinolytic proteases produced by Bacillus sp. has attracted interest in the pharmaceutical industry as a promising alternative in thrombolytic therapy due to their effectiveness in degrading fibrin, its production requiring the development of an efficient recovery process. Aqueous two-phase systems (ATPS) have been recognized as an efficient and economical process for recovering enzymes. To optimize the recovery of fibrinolytic protease from the fermentation broth of Bacillus sp. UFPEDA 485, a 23 full factorial design was used to evaluate the influence of the three independent variables PEG molar mass (MPEG), PEG concentration (CPEG) and sodium sulfate concentration (CNa2SO4) on the partition coefficient (K), purification factor (PF) and yield recovery (Y) of fibrinolytic protease in PEG/Na2SO4 aqueous two-phase system. For all ATPS studied, enzymes partitioned to the top phase and the highest extraction was obtained for MPEG 6000 g.mol-1, CPEG 24 % (w/w) and CNa2SO4 11.6 % (w/w) with K = 5.03; PF = 3.30; Y = 91.40% and Fibrinolytic activity in the top phase 821 U.mL-1. Findings reported here show that ATPS composed of PEG/Na2SO4 is a valuable strategy for the extraction of fibrinolytic protease and can be considered a promising method for the extraction of enzymes in industrial scale

    Natural and anthropogenic factors in the Guadalquivir estuary affect the abundance of anchovy in the Gulf of Cadiz (SW Spain)

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    The Gulf of Cadiz socio-ecosystem is characterized by a focal ecosystem component –the estuary of the Guadalquivir River– that has an in uence on the marine ecosystem –serves as a nursery area– and at the same time concentrates a great number of sectoral human activities. This nursery role particularly affects the anchovy fishery, which is the most economically and culturally important fishery in the region. As a transition zone between terrestrial and marine environments, estuaries are particularly sensitive to human activities, either developed directly at the aquatic environment or its surroundings. A dam 110 km upstream from the river mouth regulates freshwater input (mainly for agriculture purposes) into the estuary with consequences on turbidity and salinity. Using time series analysis on 18 years of monthly data from an estuarine monitoring program we (1) quantify the effects that natural (plankton, temperature, winds) and anthropogenic-influenced variables (freshwater volume, turbidity, salinity) have on the abundance of anchovy larvae and juveniles, and (2) relate the abundance of these estuarine-resident early stages to the abundance of adult anchovy in the sea. Water management stands out as a key node where potentially con icting interests (agriculture, power generation, aquaculture, fisheries) converge. Linking land-based activities to its impact on stock biomass represents the main challenge to ecosystem-based management in this particular regional sea. By focusing on the effects that these activities ultimately have on the anchovy fishery –via recruitment– our study aims to contribute to the process of making the ecosystem approach operational in the Gulf of Cadiz
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