Correlation between the high-frequency elastic modulus and the interparticle interaction potential in zirconium oxide colloidal suspensions

In this work, we study the high-frequency elastic modulus of aqueous suspensions made with two kinds of zirconium oxide particles, one commercially available and the other synthesized as monodisperse spheres. The effect of volume fraction of solid, ionic strength (sodium chloride as indifferent electrolyte) and particle geometry is taken into account in the study on this viscoelastic property of the suspensions. Frequency sweeps were performed at a fixed value of the applied shear-stress in order to obtain the frequency-limiting value of the elastic modulus by rheometrical methods. On the other hand, the high-frequency modulus is theoretically calculated independently by means of the models proposed by Buscall and co-workers, Wagner and Bergenholtz and co-workers, which correlate the interaction potential between particles with this rheological parameter. The approach to the interparticle potential is the extended DLVO theory, which considers the electrical repulsion between charged colloidal particles, the van der Waals attraction and the acid-base interaction that can be attractive or repulsive depending on the thermodynamic nature of the solid-liquid interfac

La quiebra del incompleto sistema de Servicios Sociales en España

Traditionally, the Social Service system has been the State’s pillar of welfare that has shown itself to be the vaguest, weakest and most sensitive to social, economic, political and cultural changes, giving rise to the need for permanent retooling. In today’s environment of neoliberal globalization, vulnerability, society at risk and structural crisis, it has a special significance: it is an even more essential system for the prevention of social exclusion, for the promotion of groups affected by inequality, such as women, and for the protection of outcasts. The situation of Social Services in Spain, however, despite the enormous effort made to get in step with the countries around us, considering its adherence to the Mediterranean sort of Welfare State, and a history with some unique characteristics which hamper a culture of care, such as a private sector with an impressive strategic capacity and a weakness in the defense of universal subjective rights, is one of deconstruction. That process, which demonstrates its growing vulnerability, is driven by a combination of two primary factors which compromise the intensity, universality of rights and equality of access to services: uncommitted, insufficient funding and imperfect decentralization.El sistema de Servicios Sociales tradicionalmente ha sido el pilar del Estado de bienestar más impreciso, más débil y más sensible a los cambios sociales, económicos, políticos, y culturales, generando una necesidad de replanteamiento permanente. En el contexto actual de globalización neoliberal, vulnerabilidad, sociedad del riesgo y crisis estructural, tiene un especial significado. Es un sistema más irrenunciable que nunca para la prevención de la exclusión social, para la promoción de los colectivos afectados por la desigualdad, como la mujer, y para la protección de los excluidos. Sin embargo, la situación de los Servicios Sociales en España, a pesar del enorme esfuerzo realizado para acompasarse con los países de nuestro entorno, y considerando su adscripción al tipo de Estado de bienestar mediterráneo y a una trayectoria con unas singularidades propias que lastra un cultura asistencialista, un sector privado con una importante capacidad estratégica y una debilidad de defensa de los derechos subjetivos universales, se encuentra en un proceso de deconstrucción. Ese proceso, que muestra su creciente vulnerabilidad, viene determinado por una combinación de dos factores principales que comprometen su intensidad, la universalidad de los derechos y la igualdad de acceso a los servicios: una financiación descomprometida e insuficiente y una descentralización imperfecta

La eliminación de metales tóxicos presentes en efluentes líquidos mediante resinas de cambio iónico. Parte III: cobre(ll)/sulfato/Amberlite 200

5 pages, 5 figures, 6 tables.[EN] Copper(II) adsorption from aqueous sulphate media on Amberlite 200 was investigated. The influence of operating variables such as aqueous pH, temperature and copper concentration on the metal adsorption kinetics was measured. The copper{II) uptake is best fitted to the film-diffusion controlled process. The resin has been used in minicolumns to investigate its performance under dynamics conditions. Copper(II) desorption from the resin is accomplished using sulphuric acid solutions.[ES] Se estudia la adsorción de cobre(II), de disoluciones en medio sulfato, en la resina Amberlite 200. La cinética de adsorción del metal se ha estudiado en función de una serie de variables experimentales: pH de la fase acuosa, temperatura y concentración del metal en el medio acuoso. La adsorción de cobre(II) se puede correlacionar como controlada por un proceso de difusión en capa límite. Se ha utilizado la resina en minicolumnas para estudiar su comportamiento bajo condiciones dinámicas. La desorción del cobre(II) se lleva a cabo con disoluciones de ácido sulfúrico.To the CSIC for support.Peer reviewe

Nota sobre «Trabajar sin destruir: trabajadores, sindicatos y ecologismo» de J. Riechmann y F. Fernández Buey (coord.)

Sin resume

Étude de la propagation acoustique en milieu complexe par des réseaux de neurones profonds

Abstract : Predicting the propagation of aerocoustic noise is a challenging task in the presence of complex mean flows and geometry installation effects. The design of future quiet propul- sion systems requires tools that are able to perform many accurate evaluations with a low computational cost. Analytical models or hybrid numerical approaches have tradition- ally been employed for that purpose. However, such methods are typically constrained by simplifying hypotheses that are not easily relaxed. Thus, the main objective of this thesis is to develop and validate novel methods for the fast and accurate prediction of aeroacoustic propagation in complex mean flows and geometries. For that, data-driven deep convolutional neural networks acting as auto-regressive spatio-temporal predictors are considered. These surrogates are trained on high-fidelity data, generated by direct aeroacoustic numerical solvers. Such datasets are able to model complex flow phenomena, along with complex geometrical parameters. The neural network is designed to substitute the high-fidelity solver at a much lower computational cost once the training is finished, while predicting the time-domain acoustic propagation with sufficient accuracy. Three test cases of growing complexity are employed to test the approach, where the learned surrogate is compared to analytical and numerical solutions. The first one corresponds to the two-dimensional propagation of Gaussian pulses in closed domains, which allows understanding the fundamental behavior of the employed convolution neural networks. Second, the approach is extended in order to consider a variety of boundary conditions, from non-reflecting to curved reflecting obstacles, including the reflection and scattering of waves at obstacles. This allows the prediction of acoustic propagation in configurations closer to industrial problems. Finally, the effects of complex mean flows is investigated through a dataset of acoustic waves propagating inside sheared flows. These applications highlight the flexibility of the employed data-driven methods using convolutional neural networks. They allow a significant acceleration of the acoustic predictions, while keeping an adequate accuracy and being also able to correctly predict the acoustic propagation outside the range of the training data. For that, prior knowledge about the wave propa- gation physics is included during and after the neural network training phase, allowing an increased control over the error performed by the surrogate. Among this prior knowledge, the conservation of physics quantities and the correct treatment of boundary conditions are identified as key parameters that improve the surrogate predictions.Prédire la propagation du bruit aéroacoustique est une tâche difficile en présence d’écoulements moyens complexes et d’effets géométriques d’installation. La conception des futurs systèmes de propulsion silencieux appelle au développement d’outils capables d’effectuer de nombreuses évaluations avec une faible erreur et un faible coût de calcul. Traditionnellement, des modèles analytiques ou des approches numériques hybrides ont été utilisés à cette fin. Cependant, ces méthodes sont généralement contraintes par des hypothèses simplificatrices qui ne sont pas facilement assouplies. Ainsi, l’objectif principal de cette thèse est de développer et de valider de nouvelles méthodes pour la prédiction rapide et précise de la propagation aéroacoustique dans des écoulements moyens et des géométries complexes. Pour cela, des réseaux de neurones profonds à convolution, entraînés sur des données, et agissant comme prédicteurs spatio-temporels sont considérés. Ces modèles par substitution sont entraînés sur des données de haute fidélité, générées par des solveurs numériques aérocoustiques directs. De telles bases de données sont capables de modéliser des phénomènes d’écoulement, ainsi que des paramètres géométriques complexes. Le réseau de neurones est conçu pour remplacer le solveur haute fidélité à un coût de calcul beaucoup plus faible une fois la phase d’entraînement terminée, tout en prédisant la propagation acoustique dans le domaine temporel avec une précision suffisante. Trois cas de test, de complexité croissante, sont utilisés pour tester l’approche, où le substitut appris est comparé à des solutions analytiques et numériques. Le premier cas correspond à la propagation acoustique bidimensionnelle dans des domaines fermés, où des sources impulsionnelles Gaussiennes sont considérées. Ceci permet de comprendre le comportement fondamental des réseaux de neurones à convolution étudiés. Deuxièmement, l’approche est étendue afin de prendre en compte une variété de conditions aux limites, notamment des conditions aux limites non réfléchissantes et des obstacles réfléchissants de géométrie arbitraire, modélisant la réflexion et la diffusion des ondes acoustiques sur ces obstacles. Cela permet de prédire la propagation acoustique dans des configurations plus proches des problématiques industrielles. Enfin, les effets des écoulements moyens complexes sont étudiés à travers une base de données d’ondes acoustiques qui se propagent à l’intérieur d’écoulements cisaillés. Ces applications mettent en évidence la flexibilité des méthodes basées sur les données, utilisant des réseaux de neurones à convolution. Ils permettent une accélération significative des prédictions acoustiques, tout en gardant une précision adéquate et en étant également capables de prédire correctement la propagation acoustique en dehors de la gamme de paramètres des données d’apprentissage. Pour cela, des connaissances préalables sur la physique de propagation des ondes sont incluses pendant et après la phase d’apprentissage du réseau de neurones, permettant un contrôle accru sur l’erreur effectuée par le substitut. Parmi ces connaissances préalables, la conservation des grandeurs physiques et le traitement correct des conditions aux limites sont identifiés comme des paramètres clés qui améliorent les prédictions du modèle proposé

Influence of childhood obesity on spatio-temporal gait parameters

Abstract The musculoskeletal and neurosensorial development of children can be affected by excess body weight. Studies have examined how childhood obesity affects gait, but much about the influence of this factor remains to be determined. The aim of our study is to analyse, in a large sample of children, the influence of obesity on the spatiotemporal parameters of the gait cycle, in the most natural way possible, with the subjects walking overground at a self-selected speed. Method. For this study, the sample was composed of 238 healthy school children, composed of 114 (47.9%) girls and 124 (52.1%) boys, aged 7 to 11 years. For each one, the body mass index was calculated, according to which the subjects were classified by percentiles as low weight, normal weight, overweight or obese. Anthropometric variables were measured and the spatiotemporal parameters of gait were assessed by the OptoGait® portable photocell system. Results. The spatial variables did not reveal significant differences between the children with normal weight and those with obesity. However, the differences for stance phase, load response and pre-swing phase (p=0.000, p=0.016 and p=0.000, respectively) were clearly significant. Conclusions. Childhood obesity exerts a significant influence on gait by increasing the duration of load response and that of the pre-swing towards the oscillation phase and therefore the total duration of the support phase. This outcome requires greater energy expenditure to stabilise the gait of children with obesity, and could have biomechanical repercussions

Perfiles tributarios de las cooperativas de 'freelance': el ejmplo faactoo.es

En los últimos años, se ha vivido a nivel mundial una auténtica explosión de las plataformas colaborativas, que actualmente son ampliamente conocidas y utilizadas por los ciudadanos europeos (Europen Commission, 2016a, p.5). Dentro de esta tendencia, se ha comenzado a extender en nuestro país el uso de las cooperativas de freelance, asimismo basadas en una plataforma online, y que ofrecen servicios variados a autónomos y/o profesionales que realizan trabajos esporádicos o eventuales, para facilitarles el desempeño de su labor

The custom-made foot orthosis using the Central Stabilizer Element: nex concept of element

Foot orthoses have been applied for the management of lower limb disorders, mainly for those who develop foot pain. The Central Stabilizer Element (CSE) is a new element that contains the midfoot laterally when a plantar insole is manufactured. OBJECTIVES: - To determine the effect on foot pain of adding the Central Stabilizer Element during the manufacturing process of foot orthosis, -- - To describe the proportions of Central Stabilizer Element in terms of width and length of this element. METHODS: A sample comprising 130 patients (57 males and 73 females) with foot pain was recruited for this study, with the patients having supinated, neutral, pronated and overpronated feet. All the patients received a custom-made foot orthosis with the Central Stabilizer Element. The Central Stabilizer Element was made of resins of polyvinyl chloride, and is a device insert in foot orthosis that contains the midfoot laterally to control pronation and supination movements. Conclusion •The students know how to design the insole. •They know how to match different foot posture with the different types of insoles •We make our decisions based on the scientific evidence foundUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Esquema metodológico para la valoración del cambio de usos del suelo (Sierra de Ayllón)

Sin resume

Gender influence on brand recommendation at an esports event

Esports events are a mainstay of the esports industry and have become increasingly popular among the younger population. The purpose of this study was to use a predictive model to determine whether the variables of congruence, commitment and trust could be predictors of brand recommendation of an esports event and, if so, to what extend they did so and whether they were influenced by gender. To obtain the required information, a questionnaire was provided, validated and made up of scales adapted from previous studies at a national esports event organised in Sevilla, Spain. The SPSS version 25 statistical software was used for the analysis of all results. First, a descriptive analysis of the results and a t-test for independent samples were performed, followed by a Pearson correlation analysis to test and independence of the three predictor variables of the recommendation. Finally, a linear regression was performed to test whether the proposed variables predicted the recommendation and, if so, to what extent they did so. The obtained results indicate that, in general, the variables significantly predicted the recommendation, with congruence being the most important predictor. The model as a whole was able to explain 51% of the variance of the recommendation. When distinguishing users by gender, the same analysis showed that the predictor variables for the recommendation remained significant in men, explaining 53% of the variance. In contrast, in the analysis of women, there were no variables that showed significant values for predicting the recommendation. These data demonstrated gender differences in the esports sector, which suggests that esports event companies should change their branding strategies to avoid gender differences