Daily precipitation intensity projected for the 21st century: seasonal changes over the Pyrenees

A set of climate parameters (mean precipitation, number of wet days, daily intensity, and number of days with more than 50mm rainfall) and a quantile-based approach are used to assess the expected changes in daily precipitation characteristics over the Pyrenees predicted for the 21st century using a set of regional climate models (RCMs). The features of the geographic location and topography of the Pyrenees imply that the climate of the region is highly complex. The results point toward an intensification of extremes, with a generalized tendency toward increasing drought periods, an increasing trend in daily intensity, and an increasing contribution of intense events to total precipitation; however, the results are subject to substantial spatial and seasonal variability, mainly related to the Atlantic-Mediterranean gradient and the longitudinal disposition of the main axis of the rang

Compact set of invariants characterizing graph states of up to eight qubits

The set of entanglement measures proposed by Hein, Eisert, and Briegel for n-qubit graph states [Phys. Rev. A 69, 062311 (2004)] fails to distinguish between inequivalent classes under local Clifford operations if n > 6. On the other hand, the set of invariants proposed by van den Nest, Dehaene, and De Moor (VDD) [Phys. Rev. A 72, 014307 (2005)] distinguishes between inequivalent classes, but contains too many invariants (more than 2 10^{36} for n=7) to be practical. Here we solve the problem of deciding which entanglement class a graph state of n < 9 qubits belongs to by calculating some of the state's intrinsic properties. We show that four invariants related to those proposed by VDD are enough for distinguishing between all inequivalent classes with n < 9 qubits.Comment: REVTeX4, 9 pages, 1 figur

Influence of the Yesa reservoir on floods of the Aragón River, central Spanish Pyrenees

International audienceThe Yesa reservoir, the largest Pyrenean reservoir, was constructed in 1959 to supply water to new irrigated areas in the Ebro Depression, NE Spain. It is filled from October to May-June and then releases large quantities of water in the summer via the Bardenas Canal. The results confirm that the frequency of floods downstream of the dam decreased. The reduction mainly depends on two factors: i) the water storage level, and ii) the season of the year. Floods are very well controlled when the reservoir level is lower than 50%. Between 50 and 70%, only the highest floods are controlled. Finally, the reservoir retains mainly autumn and spring floods; most winter floods are released downstream to ensure the safety of the dam. Keywords: reservoir, flood control, flood seasonality, flood frequency, river regime, Pyrenees</p

Fluencia en compresión de compuestos de AI2O3-SIC con distintas geometrías de reforzante

Se ha analizado la fluencia en compresión de un compuesto cerámico con matriz de alúmina reforzada con un 30% en volumen de plaquetas de SiC. Los ensayos se realizaron a 1400 °C, con velocidades de deformación entre 10'^ y x 10'^ s"\ y tensiones sobre muestra de hasta 400 MPa, alcanzándose estados cuasi estacionarios de deformación. Los resultados se comparan con los de varios compuestos de alúmina reforzada con distintos contenidos de whiskers de carburo de silicio, obtenidos previamente en idénticas condiciones experimentales. A la luz de consideraciones ampliamente aceptadas sobre los mecanismos de fluencia que actúan en estos compuestos, se discute la idoneidad de las distintas representaciones para una mejor comprensión del efecto de los reforzantes, en particular su acción como inhibidores de la fluencia por deslizamiento con acomodación de las fronteras de grano por debajo de una determinada tensión umbral.Results of compressive creep of an alumina matrix composite reinforced with different contents of silicon carbide platelets or whiskers, at temperature of 1400 C, with creep rates ranging from 10"^ to 10"^ s"-^, and true stresses up to 400 MPa has been analized. At this temperature cuasi steady-sates of deformation were achieved. New data is presented, for the material reinforced with platelets, and are compared with those obtained in the same experimental conditions for other composites reinforced with whiskers. From widely accepted considerations about the mechanisms responsible for the high temperature diffusional creep in these composites, different types of data analysis and representation of the results are showed in order to understand the effect of the reinforcements, particularly the effect on the stress tresshold needed to activate the sliding of grains during diffusional controlled creep

Threading Through Macrocycles Enhances the Performance of Carbon Nanotubes as Polymer Fillers

In this work we study the reinforcement of polymers by mechanically interlocked derivatives of single-walled carbon nanotubes (SWNTs). We compare the mechanical properties of fibers made of polymers and of composites with pristine single-walled carbon nanotubes (SWNTs), mechanically interlocked derivatives of SWNTs (MINTs) and the corresponding supramolecular models. Improvements of both Young's modulus and tensile strength of up to 200 % were observed for the polystyrene-MINTs samples with an optimized loading of just 0.01 wt.%, while the supramolecular models with identical chemical composition and loading showed negligible or even detrimental influence. This behavior is found for three different types of SWNTs and two types of macrocycles. Molecular dynamics simulations show that the polymer adopts an elongated conformation parallel to the SWNT when interacting with MINT fillers, irrespective of the macrocycle chemical nature, whereas a more globular structure is taken upon facing with either pristine SWNTs or supramolecular models. The MINT composite architecture thus leads to a more efficient exploitation of the axial properties of the SWNTs and of the polymer chain at the interface, in agreement with experimental results. Our findings demonstrate that the mechanical bond imparts distinctive advantageous properties to SWNT derivatives as polymer fillers.Comment: 39 pages, 19 figure

Parameter estimation of an empirical kinetic model for CO preferential oxidation

In this work the application of genetic algorithms (GA) for solving the parameter estimation problem in a nonlinear empirical kinetic model for CO preferential oxidation is reported. Kinetic models with nonlinear rate equations often suffer of considerable parameter uncertainty which can lead to inaccurate predictions. Here, after the parameter vector is obtained, a statistical study is performed in order to show how accurate the parameter estimations are determined. The unknown model parameters are obtained by fitting the model predictions against our laboratory observations measured under a range of experimental conditions using a novel Au/TiO2 catalyst.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Parameter estimation of an empirical kinetic model for CO preferential oxidation

In this work the application of genetic algorithms (GA) for solving the parameter estimation problem in a nonlinear empirical kinetic model for CO preferential oxidation is reported. Kinetic models with nonlinear rate equations often suffer of considerable parameter uncertainty which can lead to inaccurate predictions. Here, after the parameter vector is obtained, a statistical study is performed in order to show how accurate the parameter estimations are determined. The unknown model parameters are obtained by fitting the model predictions against our laboratory observations measured under a range of experimental conditions using a novel Au/TiO2 catalyst.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Fractura de piso orbitario en un jugador de béisbol

Presentamos un caso de un paciente, jugador de béisbol que sufrió una fractura de piso orbitario al recibir un golpe directo (blowout) con un bate que se le escapó a otro jugador, esta fractura fue reparada con un bloque de Hidroxiapatita Porosa HAP -200 .Una vez reconstruido el defecto óseo, el paciente volvió a su vida normal y comenzó de nuevo a jugar béisbol, debido a que desaparecieron la diplopía y el enoftalmo, por lo que tuvo una completa rehabilitación estética y funcional. En los exámenes radiográficos postoperatorios se observó una excelente reconstrucción del piso de la orbita y una osteointegegración del material implantológicoWe attend one patient, baseball player that suffer floor orbital fracture when he received hit in his eye (blowout) during practice baseball. He was operating and repaired this fracture with Porous Hidroxyapatite HAP-200.After operation he returned to play baseball because disappear the signs and symptoms (diplopia and enophthalmo).The radiography study showed excellent result after one yea