2,898 research outputs found
Labor Demand and Information Technologies: Evidence for Spain, 1980-2005
Using the EU KLEMS dataset we test the capital-skill complementarity hypothesis in a cross-section of sectors in Spain between 1980 and 2005. We analyze three groups of workers, who are classed according to skill level: high, medium and low. Capital assets have been broken down into ICT (information and communication technologies) assets and non-ICT assets. Acquisition and usage costs of ICT assets declined throughout the period studied, both in absolute terms and relative to the other capital assets and workers. Our principal finding is that the substitutibility between workers and ICT assets falls as worker skill level rises. In fact, the ICT assets were strongly complement with highly skilled workers and were not substitutive with them. Throughout the period analyzed, the fraction of employed medium- and high-skill workers rose by 21% and 12%, respectively, to the disadvantage of low-skill workers. After decomposing these changes, we found that the latter were dominated by an ajustment within sectors more than by a composition effect or adjustment between sectors. These adjustments may be explained by reference to the estimated elasticities of substitution.capital-skill complementarity, ICT, translog cost function, elasticity of substitution.
Thermo-hydraulic analysis and numerical simulation of a parabolic trough solar collector for direct steam generation
Direct Steam Generation (DSG) is one of the most promising alternatives for parabolic trough solar plants to replace the synthetic oil and reduce the electricity cost. The focus of this work is to develop a comprehensive optical and thermo-hydraulic model for the performance prediction of DSG process under real operating conditions. Pressure drop and heat transfer characteristics are determined considering the effect of the non-uniform heat flux distribution due to the concentration of the sunlight. A numerical-geometrical method based on ray trace and finite volume method techniques is used to determine the solar flux distribution around the absorber tube with high accuracy. A heat transfer model based on energy balance is applied to predict the thermal performances of the different flow regimes in the DSG loop. The thermo-hydraulic behavior of the different DSG sections i.e. preheating, evaporation and superheating is investigated under different operating conditions. The validity of the model has been tested by being compared with experimental data from DISS test facility and other available models in the literature. The study also presents a comparative study of the effect of different parameters on the thermal gradient around the absorber tube. The analysis shows that the highest thermal gradient is occurring in the superheating section with a high risk of thermal bending and a potential damage risk. The model is also capable to evaluate the efficiency of a DSG loop for different conditions and help to take the appropriate control strategies to avoid flow instabilities in the DSG rows.Peer ReviewedPostprint (author's final draft
Matching in vitro bioaccessibility of polyphenols and antioxidant capacity of soluble coffee by Boosted Regression Trees
The aim of this study was to evaluate changes in polyphenol profile and antioxidant capacity of five soluble coffees throughout a simulated gastro-intestinal digestion, including absorption through a dialysis membrane. Our results demonstrate that both polyphenol content and antioxidant capacity were characteristic for each type of studied coffee, showing a drop after dialysis. Twenty-seven compounds were identified in coffee by HPLC-MS, while only 14 of them were found after dialysis. Green+roasted coffee blend and chicory+coffee blend showed the highest and lowest content of polyphenols and antioxidant capacity before in vitro digestion and after dialysis, respectively. Canonical correlation analysis showed significant correlation between the antioxidant capacity and the polyphenol profile before digestion and after dialysis. Furthermore, boosted regression trees analysis (BRT) showed that only four polyphenol compounds (5-p-coumaroylquinic acid, quinic acid, coumaroyl tryptophan conjugated, and 5-O-caffeoylquinic acid) appear to be the most relevant to explain the antioxidant capacity after dialysis, these compounds being the most bioaccessible after dialysis. To our knowledge, this is the first report matching the antioxidant capacity of foods with the polyphenol profile by BRT, which opens an interesting method of analysis for future reports on the antioxidant capacity of foods.Fil: Podio, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; ArgentinaFil: López Froilán, Rebeca. Universidad Complutense de Madrid; EspañaFil: Ramirez Moreno, Esther. Universidad Autónoma de Estado de Hidalgo; México. Universidad Complutense de Madrid; EspañaFil: Bertrand, Lidwina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; ArgentinaFil: Baroni, María Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; ArgentinaFil: Pérez Rodríguez, María L.. Universidad Complutense de Madrid; EspañaFil: Sánchez Mata, María Cortes. Universidad Complutense de Madrid; EspañaFil: Wunderlin, Daniel A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Ciencia y Tecnología de Alimentos Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Ciencia y Tecnología de Alimentos Córdoba; Argentin
A Practical Environment to Apply Model-Driven Web Engineering
The application of a model-driven paradigm in the development of Web Systems has yielded very good research
results. Several research groups are defining metamodels, transformations, and tools which offer a suitable environment,
known as model-driven Web engineering (MDWE). However, there are very few practical experiences in real
Web system developments using real development teams. This chapter presents a practical environment of MDWE
based on the use of NDT (navigational development techniques) and Java Web systems, and it provides a practical
evaluation of its application within a real project: specialized Diraya.Ministerio de Educación y Ciencia TIN2007-67843-C06-03Ministerio de Educación y Ciencia TIN2007-30391-
Licensing patterns for Linked Data
Rights expression languages declare the permitted and prohibited actions to be performed on a resource. Along this work, six rights expression languages are compared, abstracting their commonalities and outlining their underlying pattern. Linked Data, which can be object of protection by the intellectual property laws or its access be restricted by an access control system, can be the asset in rights expressions. The requirements for a pattern for licensing Linked Data resources are listed
Effect of high pressure homogenization and heat treatment on physical properties and stability of almond and hazelnut milks
[EN] The effect of high pressure homogenisation (HPH) and heat treatments on physicochemical properties and physical stability of almond and hazelnut milks was studied. Vegetable milks were obtained and homogenised by applying 62, 103 and 172 MPa (MF1, MF2 and MF3, respectively). Untreated and MF3 samples were also submitted to two different heat treatments (85ºC/30 min (LH) or 121ºC/15 min (HH)). Physical and structural properties of the products were greatly affected by heat treatments and HPH. In almond milk, homogenised samples showed a significant reduction in particle size, which turned from bimodal and polydisperse to monodisperse distributions. Particle surface charge, clarity and Whiteness Index were increased and physical stability of samples was improved, without affecting either viscosity or protein stability. Hazelnut beverages showed similar trends, but HPH notably increased their viscosity while change their rheological behaviour, which suggested changes in protein conformation. HH treatments caused an increment of particle size due to the formation oil droplet-protein body clusters, associated with protein denaturation. Samples submitted to the combined treatment MF3 and LH showed the greatest stability.The authors acknowledge the financial support provided by Universitat Politecnica de Valencia (Valencia, Spain) for the project (PAID 05-11-2740). Author N. Bernat appreciates the Conselleria de Eduacion of Valencia (Spain) for a FPI Grant (Programa VALi + d para investigadores en formacion. ACIF/2011).Bernat Pérez, N.; Cháfer Nácher, MT.; Rodríguez García, J.; Chiralt, A.; González Martínez, MC. (2015). Effect of high pressure homogenization and heat treatment on physical properties and stability of almond and hazelnut milks. Food Science and Technology. 62:488-496. https://doi.org/10.1016/j.lwt.2014.10.045S4884966
Decalcifying effects of antimicrobial irrigating solutions on root canal dentin
Objective: The aim of this study was to determine the decalcifying efficacy of 7% maleic acid (MA), 2% chlorhexidine (CHX), and combinations of 7% MA + 0.2% cetrimide (CTR) and 2% CHX + 0.2% CTR, in four time periods. Study Design: Four specimens per tooth were obtained from a 2-mm thick slice of the cervical third of the root of ten human incisors. At 1, 2, 3 and 5 minutes of immersion, the concentrations of Ca2+ were measured by atomic absorption spectrophotometry. The results were analyzed using the Mann-Whitney U-test. Results: Statistically significant differences were seen for the extracted calcium in all time periods. The amount of calcium extracted by 7% MA was the highest at all four immersion times, followed by 7% MA + 0.2% CTR. Two percent CHX and its combination with 0.2% CTR extracted virtually no calcium. Conclusions: The decalcifying capacity of 7% MA and 2% CHX diminished when combined with 0.2% CTR
Linked Data Rights 2.0: extension of ODRL for Licensing Linked Data
Linked Data assets (RDF triples, graphs, datasets, mappings...) can be object of protection by the intellectual property law, the database law or its access or publication be restricted by other legal reasons (personal data pro- tection, security reasons, etc.). Publishing a rights expression along with the digital asset, allows the rightsholder waiving some or all of the IP and database rights (leaving the work in the public domain), permitting some operations if certain conditions are satisfied (like giving attribution to the author) or simply reminding the audience that some rights are reserved
Patrones de alimentación y trayectorias de crecimiento en niños con lactancia materna y con leche de fórmula durante la introducción de la alimentación complementaria
Introduction: several investigations have identified breastfeeding as a protective factor for rapid infant weight gain and childhood obesity while other studies have found that this protective effect could be the result of confounding factors. Objectives: to assess the associations between lactation practices (breast-fed vs formula-fed infants) during the introduction of complementary food period, as well as the following: a) patterns of food intake; and b) trajectories of growth at six, nine and 12 months (z-score of weight, height and body mass index [BMI] and changes in these z-scores from six to 12 months). Methods: two hundred and three infants randomly selected from Spanish Primary Health Centres were measured. Parents recorded all infant's food consumption for three days (g/day). Linear regression models were applied. Results: breast-fed infants had a lower intake of cereals, fruit baby food, vegetables with meat/fish and a total intake of food compared to formula-fed infants at nine months of age. After adjusting for sex, parental education and total food intake, breastfed children continued to have lower intake of cereals (-5.82, 95% CI: -9.22, -2.43), and lower total food intake (-301.23, 95% CI: -348.50, -253.96). Breast-fed infants had a lower change in z-score of weight, height and BMI from six to 12 months of age and these differences remained when adjusting for all confounders. Conclusions: formula-fed infants during the complementary feeding period have a higher food intake and show higher rates of rapid infant weight gain compared to breast-fed infants. These differences in growth trajectories depending on breastfeeding maintenance and food intake during early life must be considered in adiposity risk evaluation.Introducción: varios estudios han identificado la lactancia materna como un factor protector frente a la ganancia rápida de peso y la obesidad infantil, mientras que otros estudios han encontrado que este efecto protector podría ser el resultado de la interferencia de factores de confusión.
Objetivos: evaluar las asociaciones entre el tipo de lactancia (leche materna versus lactantes alimentados con fórmula) durante la introducción de la alimentación complementaria, así como: a) los patrones de ingesta de alimentos; y b) las trayectorias de crecimiento a los seis, nueve y 12 meses (z-score de peso, estatura e índice de masa corporal (IMC) y variaciones en estos z-score entre los seis y los 12 meses.
Métodos: se midieron 203 neonatos seleccionados en centros de salud primaria españoles. Los padres registraron el consumo de alimentos de todos los bebés durante tres días (g/día). Se aplicaron modelos de regresión lineal.
Resultados: los bebés alimentados con leche materna tuvieron una menor ingesta de cereales, alimentos para bebés a base de frutas, verduras con carne/pescado, así como una menor ingesta total de alimentos en comparación con los bebés alimentados con fórmula a los nueve meses de edad. Después de realizar el ajuste por sexo, educación de los padres y consumo total de alimentos, los niños alimentados con leche materna continuaron teniendo una menor ingesta de cereales (-5,82, IC 95%: -9,22, -2,43) y una ingesta total de alimentos más baja (-301,23, IC 95%: -348,50, -253,96). Los bebés alimentados al pecho tuvieron un menor incremento en la puntuación z-score de peso, talla e IMC entre los seis y los 12 meses de edad y estas diferencias se mantuvieron cuando se ajustaron para todos los factores de confusión.
Conclusiones: los lactantes alimentados con fórmula durante el periodo de alimentación complementaria tienen una mayor ingesta de alimentos y muestran tasas más altas de ganancia de peso en comparación con los lactantes alimentados con leche materna. Estas diferencias en las trayectorias de crecimiento en función del mantenimiento de la lactancia materna y la ingesta de alimentos durante los primeros años de vida deben considerarse en la evaluación del riesgo de adiposidad
Compuestos neurogénicos basados en melatonina y su uso en el tratamiento de enfermedades del sistema nervioso
La presente invención, que se incluye en el campo de
la investigación e industria farmacéutica, se refiere a
nuevas entidades químicas derivadas de melatonina
con propiedades neurogénicas, moduladoras de los
receptores de melatonina y/o serotonina,
antioxidantes y/o colinérgicas. También se refiere a
los procedimientos para la preparación de estos
nuevos compuestos, a las composiciones
farmacéuticas que los contienen y a su uso para la
fabricación de un medicamento para el tratamiento de
enfermedades del sistema nervioso relacionadas con
degeneración neuronal, depresión, trastornos
psiquiátricos y cognitivos, trauma o lesión celular, u
otro trastorno neurológico relacionado, tratamiento de
fatiga diurna, trastornos del sueño, pérdida de eficacia
mental, debilidad e irritabilidad y síntomas
relacionados con la descompensación horaria (efecto
jet-lag o síndrome transoceánico).Peer reviewedConsejo Superior de Investigaciones Científicas, Universidad Autónoma de MadridB1 Patente sin examen previ
- …