590 research outputs found

    On the spatio-temporal analysis of hydrological droughts from global hydrological models

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    The recent concerns for world-wide extreme events related to climate change have motivated the development of large scale models that simulate the global water cycle. In this context, analysis of hydrological extremes is important and requires the adaptation of identification methods used for river basin models. This paper presents two methodologies that extend the tools to analyze spatio-temporal drought development and characteristics using large scale gridded time series of hydrometeorological data. The methodologies are classified as non-contiguous and contiguous drought area analyses (i.e. NCDA and CDA). The NCDA presents time series of percentages of areas in drought at the global scale and for pre-defined regions of known hydroclimatology. The CDA is introduced as a complementary method that generates information on the spatial coherence of drought events at the global scale. Spatial drought events are found through CDA by clustering patterns (contiguous areas). In this study the global hydrological model WaterGAP was used to illustrate the methodology development. Global gridded time series of subsurface runoff (resolution 0.5°) simulated with the WaterGAP model from land points were used. The NCDA and CDA were developed to identify drought events in runoff. The percentages of area in drought calculated with both methods show complementary information on the spatial and temporal events for the last decades of the 20th century. The NCDA provides relevant information on the average number of droughts, duration and severity (deficit volume) for pre-defined regions (globe, 2 selected hydroclimatic regions). Additionally, the CDA provides information on the number of spatially linked areas in drought, maximum spatial event and their geographic location on the globe. Some results capture the overall spatio-temporal drought extremes over the last decades of the 20th century. Events like the El Niño Southern Oscillation (ENSO) in South America and the pan-European drought in 1976 appeared clearly in both analyses. The methodologies introduced provide an important basis for the global characterization of droughts, model inter-comparison of drought identified from global hydrological models and spatial event analyse

    Synthesis of Oligosaccharides Derived from Lactulose (OsLu) Using Soluble and Immobilized Aspergillus oryzae β-Galactosidase

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    β-Galactosidase from Aspergillus oryzae offers a high yield for the synthesis of oligosaccharides derived from lactulose (OsLu) by transgalactosylation. Oligosaccharides with degree of polymerization (DP) ≥ 3 have shown to possess higher in vitro bifidogenic effect than di- and tetrasaccharides. Thus, in this work, an optimization of reaction conditions affecting the specific selectivity of A. oryzae β-galactosidase for synthesis of OsLu has been carried out to enhance OsLu with DP ≥ 3 production. Assays with β-galactosidase immobilized onto a glutaraldehyde–agarose support were also carried out with the aim of making the process cost-effective and industrially viable. Optimal conditions with both soluble and immobilized enzyme for the synthesis of OsLu with DP ≥ 3 were 50 °C, pH 6.5, 450 g/L of lactulose, and 8 U/mL of enzyme, reaching yields of ca. 50% (w/v) of total OsLu and ca. 20% (w/v) of OsLu with DP 3, being 6′-galactosyl-lactulose the major one, after a short reaction time. Selective formation of disaccharides, however, was favored at 60 °C, pH 4.5, 450 g/L of lactulose and 8 U/mL of enzyme. Immobilization increased the enzymatic stability to temperature changes and allowed to reuse the enzyme. We can conclude that the use, under determined optimal conditions, of the A. oryzae β-galactosidase immobilized on a support of glutaraldehyde–agarose constitutes an efficient and cost-effective alternative to the use of soluble β-galactosidases for the synthesis of prebiotic OsLu mixturesThis work has been supported by projects AGL2014-53445-R from Ministerio de Economía y Competitividad; ALIBIRD-CM S-2013/ABI-2728 from Comunidad Autónoma de Madrid and COOPB20099 from CSI

    A Spatially Enhanced Data‐Driven Multimodel to Improve Semiseasonal Groundwater Forecasts in the High Plains Aquifer, USA

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    The aim of this paper is to improve semiseasonal forecast of groundwater availability in response to climate variables, surface water availability, groundwater level variations, and human water management using a two‐step data‐driven modeling approach. First, we implement an ensemble of artificial neural networks (ANNs) for the 300 wells across the High Plains aquifer (USA). The modeling framework includes a method to choose the most relevant input variables and time lags; an assessment of the effect of exogenous variables on the predictive capabilities of models; and the estimation of the forecast skill based on the Nash‐Sutcliffe efficiency (NSE) index, the normalized root mean square error, and the coefficient of determination (R2). Then, for the ANNs with low‐ accuracy, a MultiModel Combination (MuMoC) based on a hybrid of ANN and an instance‐based learning method is applied. MuMoC uses forecasts from neighboring wells to improve the accuracy of ANNs. An exhaustive‐search optimization algorithm is employed to select the best neighboring wells based on the cross correlation and predictive accuracy criteria. The results show high average ANN forecasting skills across the aquifer (average NSE \u3e 0.9). Spatially distributed metrics of performance showed also higher error in areas of strong interaction between hydrometeorological forcings, irrigation intensity, and the aquifer. In those areas, the integration of the spatial information into MuMoC leads to an improvement of the model accuracy (NSE increased by 0.12), with peaks higher than 0.3 when the optimization objectives for selecting the neighbors were maximized.t

    Las microfinanzas en la Argentina; sus asignaturas pendientes

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    Este estudio se enfoca en relevar las asignaturas pendientes de las microfinanzas en la Argentina, el cual se lleva a cabo a través de un análisis bibliométrico de los artículos publicados por diversas instituciones y revistas incluidas en Scopus y Redalyc, complementando la búsqueda con las publicaciones proporcionadas por la Biblioteca Electrónica de Ciencia y Tecnología de la República Argentina y el Google Schoolar en el período 2000-2015. Se seleccionaron investigaciones que abordan los aspectos relacionados a las microfinanzas en la Argentina. Cabe destacar que existe un número reducido de investigaciones sobre el tema, que predominan artículos empíricos cuyo objeto de análisis son las instituciones de microfinanzas y que existe mayor relevancia de publicaciones en el ámbito institucional u organizacional, y no así en el ámbito académico. Principalmente, las asignaturas pendientes de las microfinanzas en la Argentina fueron asociadas a aspectos de mercado (51%), seguido de aspectos legales/regulatorios (29%) y técnicos (20%). Se destacan entre los primeros, la necesidad de ampliar la cobertura y alcance de los servicios ofrecidos, y de lograr la autosustentabilidad de las instituciones microfinancieras. En relación con los aspectos legales/regulatorios, el principal aspecto radica justamente en desarrollar el marco normativo. En síntesis, se sostiene que las microfinanzas en la Argentina se encuentran en un estadio de desarrollo incipiente, mientras que diversos estudios demuestran el potencial de crecimiento del sector. Además, en general, las instituciones persiguen un fin social y solidario, no precisamente rentista

    Extreme precipitation and extreme streamflow in the Dongjiang River Basin in southern China

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    International audienceExtreme hydro-meteorological events have become the focus of more and more studies in the last decade. Due to the complexity of the spatial pattern of changes in precipitation processes, it is still hard to establish a clear view of how precipitation has changed and how it will change in the future. In the present study, changes in extreme precipitation and streamflow processes in the Dongjiang River Basin in southern China are investigated. It was shown that little change is observed in annual extreme precipitation in terms of various indices, but some significant changes are found in the precipitation processes on a monthly basis. The result indicates that when detecting climate changes, besides annual indices, seasonal variations in extreme events should be considered as well. Despite of little change in annual extreme precipitation series, significant changes are detected in several annual extreme flood flow and low-flow series, mainly at the stations along the main channel of Dongjiang River, which are affected significantly by the operation of several major reservoirs. The result highlights the importance of evaluating the impacts of human activities in assessing the changes of extreme streamflows. In addition, three non-parametric methods that are not-commonly used by hydro-meteorology community, i.e., Kolmogorov?Smirnov test, Levene's test and quantile test, are introduced and assessed by Monte Carlo simulation in the present study to test for changes in the distribution, variance and the shift of tails of different groups of dataset. Monte Carlo simulation result shows that, while all three methods work well for detecting changes in two groups of data with large data size (e.g., over 200 points in each group) and big difference in distribution parameters (e.g., over 100% increase of scale parameter in Gamma distribution), none of them are powerful enough for small data sets (e.g., less than 100 points) and small distribution parameter difference (e.g., 50% increase of scale parameter in Gamma distribution)

    Optimized Spectral Energy Distribution for Seyfert Galaxies

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    The temperature predicted by photoionization models for the Narrow Line Region of Seyfert 2 galaxies is lower than the value inferred from the observed [O III] {\lambda}4363A/{\lambda}5007A line ratio. We explore the possibility of considering a harder ionizing continuum than typically assumed. The spectral ionizing energy distribution, which can generate the observed {\lambda}4363A/{\lambda}5007A ratio, is characterized by a secondary continuum peak at 200 eV.Comment: 17 pages, 4 figures, accepted for publication in Revista Mexicana de Astronom\'ia y Astrof\'isic

    Combining semi-distributed process-based and data-driven models in flow simulation: a case study of the Meuse river basin

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    While the United Nations Principles of Responsible Management Education (PRME) is a very positive development in the horizon of management education over the last decade, there are still many significant challenges for engaging the mind of the manager in ways that will foster the values of PRME and the UN Global Compact. Responsible management education must address three foundational challenges in business education if it is to actualize the aspirations of PRME: 1) it must confront the cognitional myth that knowing is like looking, 2) it must move beyond mere analysis to systems thinking, and 3) it must transition from a values-neutral stance to a values-driven stance. Using Developing Sustainable Strategies, an MBA practicum in the Sustainable Management Concentration at DePaul University’s Kellstadt Graduate School of Business, as a case study, this article identifies the ways in which Pragmatic Inquiry can addresses these challenges. The method of Pragmatic Inquiry prepares students to become responsible managers, to develop sustainable strategies, and to be creators of shared value. Built from the philosophical foundations of American pragmatism and Bernard Lonergan’s critical realism, Pragmatic Inquiry is an effective method and pedagogy for responsible management education. The final publication is available at http://link.springer.co

    Resultados en recambios de cotilo mediante la técnica de Sloof: nuestra experiencia

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    Objetivos: osteolisis es un importante problema para el cirujano en los recambios de cotilo. Hoy en día existen múltiples técnicas para intentar subsanar este defecto. Una de ellas es la Técnica de Sloof. Hemos querido mostrar nuestros resultados con esta técnica. Material y métodos: Se revisaron 20 pacientes entre 1999 y octubre 2003 clasificados con la escala de Paprosky intervenidos con esta técnica. Se valoraron resultados en cuanto a mejoría del dolor, funcionalidad, actividad y consolidación radiológica, usando para ello las escalas de Harris. Resultados: La mayoría de los pacientes obtuvieron una mejoría significativa del dolor y una función suficiente como para realizar su vida de forma independiente, consiguiéndose la incorporación del injerto en todos los casos.Aim: The osteolysis of the pelvis is an important problem for the surgeon associated with acetabular revision. Nowadays there are many techniques which try to solve such a defect. One of them is the Sloof’s technique. We have shown our results using this technique. Materials and Methods: Study of 20 patients from 1999 to October 2003 who were treated with this technique. Results related to pain-free, functionality, activity and radiology consolidation, have been valued using Harris scale. Results: Most of patients got a significant pain diminution and a function enough to achieve their lives in a self- sufficiency way. We have obtained the graft incorporation in all the cases

    Positron range estimations with PeneloPET

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    Technical advances towards high resolution PET imaging try to overcome the inherent physical limitations to spatial resolution. Positrons travel in tissue until they annihilate into the two gamma photons detected. This range is the main detector-independent contribution to PET imaging blurring. To a large extent, it can be remedied during image reconstruction if accurate estimates of positron range are available. However, the existing estimates differ, and the comparison with the scarce experimental data available is not conclusive. In this work we present positron annihilation distributions obtained from Monte Carlo simulations with the PeneloPET simulation toolkit, for several common PET isotopes (18F, 11C, 13N, 15O, 68Ga and 82Rb) in different biological media (cortical bone, soft bone, skin, muscle striated, brain, water, adipose tissue and lung). We compare PeneloPET simulations against experimental data and other simulation results available in the literature. To this end the different positron range representations employed in the literature are related to each other by means of a new parameterization for positron range profiles. Our results are generally consistent with experiments and with most simulations previously reported with differences of less than 20% in the mean and maximum range values. From these results, we conclude that better experimental measurements are needed, especially to disentangle the effect of positronium formation in positron range. Finally, with the aid of PeneloPET, we confirm that scaling approaches can be used to obtain universal, material and isotope independent, positron range profiles, which would considerably simplify range correction.We kindly acknowledge support from Comunidad de Madrid (ARTEMIS S2009/DPI-1802), Spanish Ministry of Science and Innovation (grants FPA2010-17142 and ENTEPRASE, PSE-300000-2009-5), by European Regional Funds, by CDTI under the CENIT Programme (AMITProject) and by CPAN, CSPD-2007-00042@Ingenio2010. Part of the calculations of this work were performed in the “Cluster de Cálculo de Alta Capacidad para Técnicas Físicas” funded in part by UCM and in part by UE under FEDER programme. This is a contribution to the Campus of International Excellence of MoncloaPublicad
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