Collisions in a liquid fluidized bed

Collisional phenomena in a solid–liquid flow were studied in terms of two parameters: the collision frequency and the coefficient of restitution. Experimental measurements of these parameters were conducted inside a liquid fluidized bed by particle tracking in an index-matched array. Collision detection was based on the use of a peak acceleration threshold of the instantaneous speed of colored tracers. The measurements of collision frequency were compared with the theoretical expression derived from the kinetic theory for granular flow (KTGF). The normal and tangential restitution coefficients were measured from the trajectories before and after contact for both particle–particle and particle–wall collisions. A comparison with previous theoretical and experimental works is presented and discussed

De Xangai a la Soledat

Abstract not availabl

Impressions entorn de la integració a EE.MM.

Abstract not availabl

Morbilidad materna y perinatal en pacientes diagnosticadas con preeclampsia grave y eclampsia ingresadas en el servicio de Ginecoobstetricia del Hospital Alemán Nicaragüense en el periodo comprendido de Enero a Diciembre de 2015

Los Trastornos Hipertensivos constituyen una de las complicaciones médicas más frecuentes en el embarazo, con una incidencia reportada que varía entre 5 a 15%; asociándose a un aumento de la morbimortalidad materna, fetal y neonatal. (14). De un 3 a 15% de los embarazos, se complican a causa de la Preeclampsia a nivel mundial, según una estimación de la OMS más de 200.000 muertes maternas ocurren cada año en el mundo como consecuencia de las complicaciones derivadas de la preeclampsia-eclampsia y contribuye con un porcentaje considerable de muertes perinatales y maternas; estimándose una mortalidad fetal alrededor de 30 %, que aún en países desarrollados constituye un problema de salud materna importante; ya que el tratamiento no es curativo, y observándose mayor morbilidad en aquellas enfermas que desarrollan la enfermedad antes de la 33 semanas de gestación, en quienes padecen enfermedades previas, y en poblaciones pertenecientes a naciones subdesarrolladas

The impact of COVID-19 on analysts’ sentiment about the banking sector

La aplicación de herramientas cuantitativas que facilitan el análisis de la inmensa cantidad de información disponible ha ido ganando cada día más importancia. Son varios los participantes del mercado que se han unido a esta tendencia, y los bancos centrales no escapan de ella. Gran parte de la información cualitativa es no estructurada, principalmente en forma de noticias, informes u otro tipo de textos. Por lo tanto, la automatización de este proceso puede incrementar el volumen de información disponible y el proceso de toma de decisiones. Este trabajo se enmarca en esta tendencia, mediante el uso de herramientas de análisis de sentimiento para determinar el impacto del COVID-19 en la opinión de los analistas sobre el sector bancario. Gracias a esta metodología, se logra convertir una información cualitativa, no estructurada, en un índice cuantitativo que permite comparar informes de diferentes períodos y países. Como resultado, se observa un empeoramiento del sentimiento sobre la banca europea, lo que coincide con una mayor incertidumbre en las cotizaciones bursátiles. Además, se aprecian diferencias entre países, así como una mayor divergencia en las opiniones reflejadas en los informes.The use of quantitative tools to analyse the huge amount of qualitative information has been acquiring increasing importance. Market participants and, of course, Central Banks have been involved in this trend. The vast majority of qualitative data can be qualified as non-structured and refers mainly to news, reports or another kind of texts. Its transformation into structured data can improve the availability of information and hence, decision making. This article applies sentiment analysis tools to text data in order to quantify the impact of Covid-19 on the analysts’ opinions. Using this methodology, it is possible to transform qualitative non-structured data into a quantitative index that can be used to compare reports from different periods and countries. The results show the pandemic worsens banking sentiment in Europe, which coincides with higher uncertainty in the stock market. There are also regional differences in the decline in sentiment as well as higher divergence is observed across opinions

Radiolysis of Serine in High Radiation Field

The formation of amino acids under simulated condition suggests that this type of compounds were readily formed on the primitive Earth. Nevertheless, there is no conclusive explanation to the origin of their specific chirality in biological systems. Differences in their stability in the primitive conditions may give some clues about this unsolved problem. Protection mechanisms have been considered, such as the adsorption of the organic compounds onto mineral surfaces. By using HPLC/ELSD to analyze aqueous suspensions of serine adsorbed on clay (sodium montmorillonite) and a meteorite (Allende) irradiated in different doses with a cobalt-60 gamma source, the aim of this work was to study the possible protector role of these mineral surfaces when an amino acid, serine, is adsorbed onto them and the system is exposed to a high radiation source. The results showed that adsorption is better at acidic pH and desorption from the mineral at basic pH. The irradiation of the free amino acid destroyed it almost completely at a dose of 91 kGy, but the presence of the mineral abruptly decreases the decomposition, acting as a protective agent. At the same time, the results in aqueous solution show no statistically significant differences in adsorption or radiolysis of D and L serine

Pairwise gene GO-based measures for biclustering of high-dimensional expression data

Background: Biclustering algorithms search for groups of genes that share the same behavior under a subset of samples in gene expression data. Nowadays, the biological knowledge available in public repositories can be used to drive these algorithms to find biclusters composed of groups of genes functionally coherent. On the other hand, a distance among genes can be defined according to their information stored in Gene Ontology (GO). Gene pairwise GO semantic similarity measures report a value for each pair of genes which establishes their functional similarity. A scatter search-based algorithm that optimizes a merit function that integrates GO information is studied in this paper. This merit function uses a term that addresses the information through a GO measure. Results: The effect of two possible different gene pairwise GO measures on the performance of the algorithm is analyzed. Firstly, three well known yeast datasets with approximately one thousand of genes are studied. Secondly, a group of human datasets related to clinical data of cancer is also explored by the algorithm. Most of these data are high-dimensional datasets composed of a huge number of genes. The resultant biclusters reveal groups of genes linked by a same functionality when the search procedure is driven by one of the proposed GO measures. Furthermore, a qualitative biological study of a group of biclusters show their relevance from a cancer disease perspective. Conclusions: It can be concluded that the integration of biological information improves the performance of the biclustering process. The two different GO measures studied show an improvement in the results obtained for the yeast dataset. However, if datasets are composed of a huge number of genes, only one of them really improves the algorithm performance. This second case constitutes a clear option to explore interesting datasets from a clinical point of view.Ministerio de Economía y Competitividad TIN2014-55894-C2-

PIV measurements of the effect of pulsed blowing jet on a NACA0012 wing model

Wingtip vortices are present in taking off, and landing operations and their presence in airport runways must be reduced. To that end, several strategies have been considered in the last decades, being the active control one possible technical solution. To compute the effectiveness of active control that corresponds to pulsed low-blowing-ratio transverse jet for the reduction of the wingtip vortex strength, we carry out 2D-PIV measurements in a towing tank for chord-based Reynolds numbers 15000 and 20000. We consider two cases: (i) no active control Rjet=0 and (ii) pulsating radial jet of blowing-ratio Rjet smaller than 1.7 (or momentum coefficient lower than 0.12) and different Strouhal numbers ranging from 0.27 to 0.94. Our observations show that the best reduction of wingtip vortex strength takes place at the lowest Strouhal number tested. We use the maximum azimuthal velocity and vorticity together with the circulation to quantify this decrease in the vortex strength. Besides, we define the spatial evolution of a disturbance parameter which allow us to detect again the optimal frequency that leads to vortex destruction.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Agitation des particules dans un lit fluidisé liquide. Etude expérimentale

Dans ce travail, les trajectoires 3-D de particules marquées dans un lit fluidisé liquide ont été mesurées par vidéo dans un milieu d’indices optiques ajustés, dans une plage étendue de concentration. Les paramètres de l’écoulement étudié correspondent à des nombres de Reynolds particulaire élevés ( O( 10) < Rep< O( 103) et des nombres de Stokes intermédiaires ( O( 1) < St< O( 10) ) L’évolution de l’énergie cinétique fluctuante des particules en fonction de la concentration a été modélisée et interprétée dans le cadre de la théorie cinétique. Le coefficient d’autodiffusion des particules a été identifié dans les plans horizontal et vertical, et modélisé grâce à une analyse comparative d’échelles de temps. La fréquence et le coefficient de restitution des collisions ont été mesurés et comparés aux modèles existants. ABSTRACT : Besides its interest as an industrial application in various processes, liquid fluidization builds up an interesting test case regarding the validation of two-phase flow modelling. The lack of reliable and detailed experimental data about particle agitation in this type of flow is one important motivation to this study. In this work, the random motion of mono-dispersed particles in a liquid fluidized bed has been measured and processed from video recordings, using a refractive index matching method. 3-D trajectories of coloured particles have been collected in a wide range of solid fraction, and statistical quantities have been derived in the range of high particle Reynolds number ( O( 10) < Rep< O( 103) and intermediate Stokes number ( ( O( 1) < St< O( 10) ) . The evolution of the particle velocity variance as a function of solid fraction has been modelled and interpreted in the frame of kinetic theory of granular flows (KTGF) . The fluctuating kinetic energy of the continuous phase measured by PIV, is significantly larger than that of the dispersed phase and varies almost linearly as a function of the slip velocity. The existence of a diffusive motion of the particles has been demonstrated and the self-diffusion coefficient has been identified using two distinct methods, the velocity autocorrelation function and the variance of the particle displacement. The comparison of characteristic time scales of the particles and the fluid at small and large scales allowed the formulation of scaling laws for this quantity. Finally, the collisions frequency and particle-wall rebound have been measured and analyzed in the frame of existing theories