Estudio de la cristalización de ZrO2 en el sistema sol-gel: ZrO2-SiO2

Los polvos en el sistema ZrO2-SiO2, obtenidos por el método sol-gel, se produjeron utilizando alcóxido de silicio (TEOS) y propóxido de zirconio. Después de la gelación, se investigó la cristalización del ZrO2 por difracción de rayos X (DRX), análisis térmico (ATD/ATG), y microscopía electrónica de barrido (MEB). Los geles frescos eran amorfos. Se llevaron a cabo tratamientos térmicos de 100 hasta 1400°C, manteniéndolos por períodos de tiempo de hasta182h. La primera fase en cristalizar fue la zirconia tetragonal Z(t), entre 300 y 500°C. La temperatura de cristalización para las composiciones ricas en zirconia fue menor y aumentó a medida que el contenido de sílice aumentaba. El análisis térmico diferencial (ATD) mostró que la cristalización de Z(t) ocurría en dos pasos. La transformación de zirconia tetragonal a monoclínica ocurría a 1000°C y era claramente observada sólo en composiciones ricas en zirconia (>80%). La sílice permanecía amorfa hasta 1200°C, cuando se formaba la fase ZrSiO4. Se propuso un diagrama de fases sol-gel metaestable para mostrar el proceso de cristalización en el intervalo de temperatura de 100 a 1400°C

Influencia de la accesibilidad y distancia en el consumo de productos sanitarios en una Unidad de Hemodialisis

Objetivo: determinar si la distancia que deben recorrer las enfermeras para acceder a tres productos sanitarios (gasas, apósitos y sueros fisiológicos) influye en la cantidad consumida en el Gabinete de Hemodiálisis de la Fundació Puigvert (2013-2014). Método: estudio cuasiexperimental en el total de las enfermeras del Gabinete de Hemodiálisis (n= 30). Variable principal: consumo de unidades de tres productos sanitarios (gasas, apósitos y sueros fisiológicos). Variable de intervención: distancia a donde se encontraban los productos sanitarios (5, 7 y 9 m), que fue modificada cada dos meses. En el análisis bivariante se utilizó el coeficiente de correlación de Spearman, el test de Wilcoxon y la prueba U Mann Whitney. Resultados: existía una correlación lineal inversa, de manera que a mayor edad o años de profesión, menor consumo de los productos sanitarios estudiados. Al comparar el consumo a los 7 y 9 m versus los 5 m, se vio que era inferior para todos los productos (p< 0,05). El consumo de gasas y apósitos fue mayor (p< 0,05) en el turno de tarde en todas las distancias exploradas. Conclusiones: a mayor distancia de los productos sanitarios suero fisiológico, gasas y apósitos, menor es el consumo de los mismos por parte de las enfermeras. Existe una asociación estadísticamente significativa entre el consumo, la edad y la experiencia, de manera que las enfermeras más jóvenes y con menos experiencia consumen más

Influence of accesibility and distance in the consumption of disposable equipment in a hemodialysis unit

The location of the disposable material in a hemodialysis unit is essential to ensure the effectiveness of the circuits and to provide quality in nursing care. The law of the minimum effort may explain how the accessibility and distance of dressing trolleys can influence the consumption of some health care supplies [1,2]. It is necessary for health managers to look for effective strategies that optimize the use of wound care material without reducing the quality of care [1,3]. The objective was to determine whether the distance that nurses have to walk to access the trolley with the wound care material (gauzes, dressings and 10cc physiological serum), influence on the amount consumed in a hemodialysis unit at the Fundació Puigvert. The research hypothesis is: consumption of those materials will decrease 5% as the distance to access the trolleys increases from 5 to 7 and from 7 to 9 meters

The distribution of transit durations for Kepler planet candidates and implications for their orbital eccentricities

‘In these times, during the rise in the popularity of institutional repositories, the Society does not forbid authors from depositing their work in such repositories. However, the AAS regards the deposit of scholarly work in such repositories to be a decision of the individual scholar, as long as the individual's actions respect the diligence of the journals and their reviewers.’ Original article can be found at : http://iopscience.iop.org/ Copyright American Astronomical SocietyDoppler planet searches have discovered that giant planets follow orbits with a wide range of orbital eccentricities, revolutionizing theories of planet formation. The discovery of hundreds of exoplanet candidates by NASA's Kepler mission enables astronomers to characterize the eccentricity distribution of small exoplanets. Measuring the eccentricity of individual planets is only practical in favorable cases that are amenable to complementary techniques (e.g., radial velocities, transit timing variations, occultation photometry). Yet even in the absence of individual eccentricities, it is possible to study the distribution of eccentricities based on the distribution of transit durations (relative to the maximum transit duration for a circular orbit). We analyze the transit duration distribution of Kepler planet candidates. We find that for host stars with T > 5100 K we cannot invert this to infer the eccentricity distribution at this time due to uncertainties and possible systematics in the host star densities. With this limitation in mind, we compare the observed transit duration distribution with models to rule out extreme distributions. If we assume a Rayleigh eccentricity distribution for Kepler planet candidates, then we find best fits with a mean eccentricity of 0.1-0.25 for host stars with T ≤ 5100 K. We compare the transit duration distribution for different subsets of Kepler planet candidates and discuss tentative trends with planetary radius and multiplicity. High-precision spectroscopic follow-up observations for a large sample of host stars will be required to confirm which trends are real and which are the results of systematic errors in stellar radii. Finally, we identify planet candidates that must be eccentric or have a significantly underestimated stellar radius.Peer reviewedFinal Accepted Versio

A transiting companion to the eclipsing binary KIC002856960

We present an early result from an automated search of Kepler eclipsing binary systems for circumbinary companions. An intriguing tertiary signal has been discovered in the short period eclipsing binary KIC002856960. This third body leads to transit-like features in the light curve occurring every 204.2 days, while the two other components of the system display eclipses on a 6.2 hour period. The variations due to the tertiary body last for a duration of \sim1.26 days, or 4.9 binary orbital periods. During each crossing of the binary orbit with the tertiary body, multiple individual transits are observed as the close binary stars repeatedly move in and out of alignment with the tertiary object. We are at this stage unable to distinguish between a planetary companion to a close eclipsing binary, or a hierarchical triply eclipsing system of three stars. Both possibilities are explored, and the light curves presented.Comment: Accepted into A&A Letters (5 pages & 3 figures

Dynamical analysis and constraints for the HD 196885 system

The HD\,196885 system is composed of a binary star and a planet orbiting the primary. The orbit of the binary is fully constrained by astrometry, but for the planet the inclination with respect to the plane of the sky and the longitude of the node are unknown. Here we perform a full analysis of the HD\,196885 system by exploring the two free parameters of the planet and choosing different sets of angular variables. We find that the most likely configurations for the planet is either nearly coplanar orbits (prograde and retrograde), or highly inclined orbits near the Lidov-Kozai equilibrium points, i = 44^{\circ} or i = 137^{\circ} . Among coplanar orbits, the retrograde ones appear to be less chaotic, while for the orbits near the Lidov-Kozai equilibria, those around \omega= 270^{\circ} are more reliable, where \omega_k is the argument of pericenter of the planet's orbit with respect to the binary's orbit. From the observer's point of view (plane of the sky) stable areas are restricted to (I1, \Omega_1) \sim (65^{\circ}, 80^{\circ}), (65^{\circ},260^{\circ}), (115^{\circ},80^{\circ}), and (115^{\circ},260^{\circ}), where I1 is the inclination of the planet and \Omega_1 is the longitude of ascending node.Comment: 10 pages, 7 figures. A&A Accepte

Impacto de la ubicación-lateralidad en el consumo de productos sanitarios en una unidad de hemodiálisis

INTRODUCCIÓN. El objetivo es determinar si la ubicación-late­ralidad dentro del carro de curas de tres recursos sanitarios (gasas, apósitos y sueros fisiológicos [SF] de 1 O ce) influye en la cantidad de material consumido en el Gabinete de Hemo­diálisis de la Fundació Puigvert. METODOLOGÍA. Estudio cuasi experimental, sin grupo control tipo postest. Muestra formada por treinta enfermeras exper­tas (muestreo no probabilístico de conveniencia). El estudio se realizó entre marzo y agosto de 2014. Durante dos meses, los tres productos sanitarios permanecieron en el lado dere­cho del carro de curas, durante dos meses en el centro y, fi­nalmente, dos meses en el lado izquierdo. El análisis se realizó mediante el software estadístico SPSS. Para todas las pruebas se utilizó un nivel de significación .005). El consumo de apósitos es mayor en el lado derecho que en el centro (p < .001 ). El consumo de los tres productos sanitarios es inferior cuando se colocan en el lado izquierdo del carro en compa­ración con su ubicación en el centro (p < .001) o en el lado derecho (p < .001 ). CONCLUSIONES. La ubicación-lateralidad tiene una influencia directa en el consumo de material sanitario. El consumo en el lado izquierdo es inferior que en el centro y en el lado de­recho. La ubicación-lateralidad es una buena estrategia de gestión

Cost-sensitive ordinal classification methods to predict SARS-CoV-2 pneumonia severity

Objective: To study the suitability of cost-sensitive ordinal artificial intelligence-machine learning (AI-ML) strategies in the prognosis of SARS-CoV-2 pneumonia severity. Materials & methods: Observational, retrospective, longitudinal, cohort study in 4 hospitals in Spain. Information regarding demographic and clinical status was supplemented by socioeconomic data and air pollution exposures. We proposed AI-ML algorithms for ordinal classification via ordinal decomposition and for cost-sensitive learning via resampling techniques. For performance-based model selection, we defined a custom score including per-class sensitivities and asymmetric misprognosis costs. 260 distinct AI-ML models were evaluated via 10 repetitions of 5×5 nested cross-validation with hyperparameter tuning. Model selection was followed by the calibration of predicted probabilities. Final overall performance was compared against five well-established clinical severity scores and against a ‘standard’ (non-cost sensitive, non-ordinal) AI-ML baseline. In our best model, we also evaluated its explainability with respect to each of the input variables. Results: The study enrolled $n$=1548 patients: 712 experienced low, 238 medium, and 598 high clinical severity. $d$=131 variables were collected, becoming $d′$=148 features after categorical encoding. Model selection resulted in our best-performing AI-ML pipeline having: a) no imputation of missing data, b) no feature selection (i.e. using the full set of $d′$ features), c) ‘Ordered Partitions’ ordinal decomposition, d) cost-based reimbalance, and e) a Histogram-based Gradient Boosting classifier. This best model (calibrated) obtained a median accuracy of 68.1% [67.3%, 68.8%] (95% confidence interval), a balanced accuracy of 57.0% [55.6%, 57.9%], and an overall area under the curve (AUC) 0.802 [0.795, 0.808]. In our dataset, it outperformed all five clinical severity scores and the ‘standard’ AI-ML baseline. Discussion & conclusion: We conducted an exhaustive exploration of AI-ML methods designed for both ordinal and cost-sensitive classification, motivated by a real-world application domain (clinical severity prognosis) in which these topics arise naturally. Our model with the best classification performance exploited successfully the ordering information of ground truth classes, coping with imbalance and asymmetric costs. However, these ordinal and cost-sensitive aspects are seldom explored in the literature