3,557 research outputs found
Point rainfall statistics for ecohydrological analyses derived from satellite integrated rainfall measurements
ABSTRACT: Satellite rainfall measurements, nowadays commonly available, provide valuable information about the spatial structure of rainfall. In areas with low-density rain gage networks, or where these networks are nonexistent, satellite rainfall measurements can also provide useful estimates to be used as virtual rain gages. However, satellite and rain gage measurements are statistically different in nature and cannot be directly compared to one another. In the present paper, we develop a methodology to downscale satellite rainfall measurements to generate rain-gage-equivalent statistics. We apply the methodology to four locations along a strong rainfall gradient in the Kalahari transect, southern Africa, to validate the methodology. We show that the method allows the estimation of point rainfall statistics where only satellite measurements exist. Point rainfall statistics are key descriptors for ecohydrologic studies linking the response of vegetation to rainfall dynamics
The Effect of Cr Concentration on Defect Energies in FeCr Alloys
FeCr ferritic alloys are leading candidates for structural applications in generation IV fission reactors due to their high resistance to swelling and corrosion.
The addition of Cr improves the behavior of the steels under irradiation, but this improvement is non-monotonic. Understandig the changes in the FeCr ferritic alloys
microstructure induced by irradiation and the role played by the alloying element (Cr) is needed in order to predict the response of these materials under the extreme
conditions in the future nuclear plants. In this work, we present the effect of Cr concentration in a bcc Fe matrix on binding and formation energies of vacancy clusters
A comparison of Clinical Risk Index for babies (CRIB-II), Score for Neonatal Acute Physiology (SNAP-II) and SNAPPE-II in predicting parenteral nutrition necessity in low birth weight preterm neonates.
Advances in perinatal care have made it possible to improve survival of low birth weight neonates. Clinical risk index for babies (CRIB-II), score for neonatal acute physiology (SNAP-II), and SNAP-perinatal extension-II (SNAPPE-II) have been used as mortality predictors for preterm infants. Feeding intolerance is very frequent in preterm neonates, and the development of an early effective biomarker for its prediction could be useful for carrying out a proper feeding strategy. Our aim was to compare the ability of CRIB-II, SNAP-II and SNAPPE-II in predict the feeding intolerance and parenteral nutrition necessity in preterm neonates.
Methods: A retrospective cohort study on preterm neonates’ born at Jaen Hospital Complex with low birth weight and ≤ 36 weeks of gestation was done. Epidemiological, clinical and clinical scores CRIB II, SNAP-II and SNAPPE-II were recorded.
Results: 255 low birth weight preterm neonates, 131 males (51.4%), aged ≤32 weeks of gestation (71%), were enrolled at our hospital. Parenteral nutrition needed were significantly higher in preterm neonates weighed 2500-1500 g (73.3%) and ≤ 1000g (87%). CRIB-II, SNAP-II and SNAPPE-II mean values were higher in neonates group subjected to parenteral nutrition compared with oral nutrition (p<0.05). CRIB-II and SNAPPE-II scores significantly correlated with parenteral nutrition days (p<0.05). Overall mortality rate was 11%. The 78.6% of all deceased infants needed parenteral nutrition.
Conclusion: Clinical Risk Index for babies (CRIB-II) better than SNAPPE-II correlated with the feeding intolerance and thus the parenteral nutrition days in preterm neonates with low birth weight.Subvencionado: Ayuda del Plan Propio de Investigación de la UMA. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Deffect energetics in FeCr from empirical interatomic potentials
We present a comparative study between two empirical potentials for the study of FeCr alloys. Vacancy, self- and mixed interstitials formation energies are investigated for both potentials in pure bcc Fe and pure bcc Cr. These results are compared to DFT values reported in literature. Some small Cr clusters in substitutional positions have also been studied in bcc Fe. Finally we have performed some calculations of the vacancy formation energy (Ev) depending on Cr concentration
Control interno y gestión administrativa en la Municipalidad Distrital de Jayanca
La presente investigación titulada Control Interno y gestión administrativa de la
Municipalidad Distrital de Jayanca, tuvo como objetivo de estudio determinar la
relación que existe entre el Control interno y gestión administrativa en la MDJ;
siendo un estudio de tipo aplicada, con enfoque cuantitativo y diseño no
experimental, transversal y correlacional, que permite conocer la asociación de
las variables y sus correspondientes dimensiones. La técnica empleada para la
recolección de datos fue la encuesta, la muestra estuvo conformada por 120
trabajadores de la Municipalidad Distrital de Jayanca, a quienes se le aplicó un
cuestionario por cada variable, los mismos que fueron validados por expertos y
sometidos a la prueba de confiabilidad de Alpha de Cronbach, teniendo un
resultado de 0.961 para la primera variable y de 0.959 para la segunda
variable. Los resultados muestran un coeficiente de correlación de Rho
Spearman de 0.804 y con un valor de significancia 0.001, concluyendo que, si
mejora el control interno, mejorará la gestión administrativa en la Municipalidad
Distrital de Jayanca
The role of forest maturity in extreme hydrological events
This study aims to clarify the influence of forests, as well as other prevalent land cover types, on extreme hydrological events through a land cover gradient design. We selected 10 catchments within a gradient of forest land cover, in which there were 15 years of simultaneous daily hydrological and meteorological data, and an additional forest descriptor, forest maturity. The study was developed in a heterogeneous region in the Cantabrian Mountains (NW Spain). This area includes different vegetation types and has a long history of human disturbance and land use change that has produced a gradient in forest cover. This study focuses on regular hydrological extremes: regular floods and low flow events. Specific objectives were to observe the relationship between land cover and extreme hydrological events, once the variance explained by precipitation was removed, and compare the effectiveness of forest coverage and maturity to predict them. Partial correlations and ordinary least square regressions were developed using hydrological indices, obtained from flow records, and hydrological parameters calculated through modelling, using the Identification of unit Hydrographs And Component flows from Rainfall, Evaporation and Streamflow data (IHACRES) software and hydrometeorological data. Land cover characteristics were better able to predict floods than low flows. Forests were associated with less extreme flow events (lower intensity and frequency of floods and greater base flows), whereas shrub formations did the opposite. These results were more evident using forest maturity than using forest coverage. This study indicates that hydrological modelling may benefit in the future from considering not only the coverage of different land cover types but also the conservation status of the different vegetation formations.info:eu-repo/semantics/acceptedVersio
Key paramaters in the design of HiPER reaction chamber
The future chamber reactor of HiPER will have to withstand short energy pulses (3 μs long) of up to 5 MJ of charged particles and X-rays with different repetition rates. Nowadays, tungsten has been selected as first wall material for a 5m radius reaction chamber. From the thermo-mechanical point of view, experiments have demonstrated that tungsten can withstand heat flux parameters up to 28 MJm-2 s -1/2 without roughening and 40 MJm-2 s -1/2 without undergoing melting. From the atomic point of view, He retention and bubble formation represents the biggest threat to its survivability, being doses of ~10 17 He/cm2 the upper limit for safe operation. Comparison of these limiting values with those proposed for a 48 MJ shock ignition target in HiPER reveals that, under a reasonable plan of 1000 fusion shots during the chamber lifetime, tungsten should guarantee a proper performance of the first wall
A compositional Eulerian approach for modeling oil spills in the sea
We present a Compositional Eulerian model to forecast the evolution of oil spills in the sea. The model allows studying the fate of not only the oil concentration but also of each component (e.g., volatile, non-volatile, water in the oil). Therefore, the problem is formulated as a conservation equation for each component, plus an equation to estimate the age of the oil, which allows us to assess weathering processes (e.g., evaporation, natural dispersion, emulsion) and the associated changes in oil properties. We describe an efficient implementation, using second order numerical schemes for advection and nonlinear diffusion terms, to reduce numerical diffusion. We perform numerical experiments, based on real and synthetic cases, to illustrate and validate the capabilities of our model to forecast the evolution of oil spills and to perform environmental risk analysis in the case of a potential accident
Materials Research for HiPER Laser Fusion Facilities: Chamber Wall, Structural Material and Final Optics.
The European HiPER project aims to demonstrate commercial viability of inertial fusion energy within the following two decades. This goal requires an extensive Research &Development program on materials for different applications (e.g., first wall, structural components and final optics). In this paper we will discuss our activities in the framework of HiPER to develop materials studies for the different areas of interest. The chamber first wall will have to withstand explosions of at least 100 MJ at a repetition rate of 5-10 Hz. If direct drive targets are used, a dry wall chamber operated in vacuum is preferable. In this situation the major threat for the wall stems from ions. For reasonably low chamber radius (5-10 m) new materials based on W and C are being investigated, e.g., engineered surfaces and nanostructured materials. Structural materials will be subject to high fluxes of neutrons leading to deleterious effects, such as, swelling. Low activation advanced steels as well as new nanostructured materials are being investigated. The final optics lenses will not survive the extreme ion irradiation pulses originated in the explosions. Therefore, mitigation strategies are being investigated. In addition, efforts are being carried out in understanding optimized conditions to minimize the loss of optical properties by neutron and gamma irradiatio
Evaluation of the reliability of commercial concentrator triple-junction solar cells by means of accelerated life tests (ALT)
A temperature accelerated life test on commercial concentrator lattice-matched GaInP/GaInAs/Ge triple-junction solar cells has been carried out. The solar cells have been tested at three different temperatures: 119, 126 and 164 °C and the nominal photo-current condition (820 X) has been emulated by injecting current in darkness. All the solar cells have presented catastrophic failures. The failure distributions at the three tested temperatures have been fitted to an Arrhenius-Weibull model. An Arrhenius activation energy of 1.58 eV was determined from the fit. The main reliability functions and parameters (reliability function, instantaneous failure rate, mean time to failure, warranty time) of these solar cells at the nominal working temperature (80 °C) have been obtained. The warranty time obtained for a failure population of 5 % has been 69 years. Thus, a long-term warranty could be offered for these particular solar cells working at 820 X, 8 hours per day at 80 °C
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