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.

Critical current density and ac harmonic voltage generation in YBa2Cu3O7−δYBa_2Cu_3O_{7-\delta} thin films by the screening technique

The temperature and field dependence of harmonics in voltage $V_n=V'_n-iV"_n$ using the screening technique have been measured for $\mathrm{Y}\mathrm{Ba}_{2}\mathrm{Cu}_3\mathrm{O}_{7-\delta}$ superconducting thin films. Using the Sun model we obtained the curves for the temperature-dependent critical current density $J_c(T)$. In addition, we applied the criterion proposed by Acosta et al. to compute $J_c(T)$. Also, we made used of the empirical law $J_c \propto (1-T/T_c)^n$ as an input in our calculations to reproduce experimental harmonic generation up to the fifth harmonic. We found that most models fit well the fundamental voltage but higher harmonics are poorly reproduced. Such behavior suggests the idea that higher harmonics contain information concerning complex processes like flux creep or thermally assisted flux flow.Comment: 2 pages, 2 figure

WebODE: An integrated workbench for ontology representation, reasoning, and exchange

We present WebODE as a scalable, integrated workbench for ontological engineering that eases the modelling of ontologies, the reasoning with ontologies and the exchange of ontologies with other ontology tools and ontology-based applications. We will first describe the WebODE's knowledge model. We will then describe its extensible architecture, focusing on the set of independent ontology development functionalities that are integrated in this framework, such as the Ontology Editor, the Axiom Builder, the OKBC-based inference engine, and the documentation and interoperability services

Palynology of the Permian San Miguel Formation (Western Paraná Basin, Paraguay): Gondwanan biostratigraphic correlations

The palynological analysis of five samples from three levels in cores of the Mallorquín-1 well (Paraná Basin, eastern Paraguay) is presented here. The borehole penetrated the San Miguel Formation, the basal lithostratigraphic unit of the Independencia Group. This palynoflora represents the westernmost palynological record reported from Upper Paleozoic sequences along this basin margin at this latitude. This diverse spore-pollen flora includes several age marker taxa, viz. Verrucosisporites insuetus, Lueckisporites spp., Lunatisporites variesectus, Striatosporites heyleri, Weylandites lucifer, and Tornopollenites toreutos, as well as Reduviasporonites chalastus. The assemblages from the Mallorquín-1 well are assignable to the Lueckisporites virkkiae Zone from the Brazilian sector of the Paraná Basin, thus suggesting a Late Cisuralian-Guadalupian age for the section studied and its correlation with the Brazilian Palermo and Irati Formations. Moreover, palynostratigraphic regional correlation can be established with the Tornopollenites toreutos Biozone (northern Brazil), the Striatites and Lueckisporites-Weylandites Biozones (Argentina) and the Striatoabieites anaverrucosus-Staurosaccites cordubensis Biozone (Uruguay). The presence of abundant taeniate pollen also suggests similarities with palynofloras from South Africa and Australia

La relevancia de la nueva información transmitida por los dividendos en el mercado de capitales español

En este trabajo pretendemos contrastar el efecto del contenido informativo de los dividendos en el mercado de capitales español. La decisión de reparto de dividendos constituye uno de los temas más controvertidos dentro de las finanzas empresariales presentándose, en palabras de Black, como un rompecabezas cuyas piezas no acaban de encajar entre sí. En un mercado de capitales perfectos esta decisión se convierte en una decisión irrrelevante para las políticas de inversión de las empresas, tal como demostraron Miller y Modigliani. Sin embargo, el escaso poder predictivo de este modelo, bajo el supuesto simplista de ausencia de imperfecciones hace necesario la búsqueda de nuevas respuestas que permitan acercar los pronósticos de la teoría al comportamiento adoptado por las empresas en materia de reparto. Uno de los argumentos que ofrece respuesta a la decisión de dividendos es el que atañe al carácter señalizador de los dividendos. En este sentido, al hilo de las proposiciones que nos sugiere la teoría de la agencia, la política de reparto puede usarse como un vehículo en manos de la gerencia para transmitir información al mercado, en un mundo de asimetrías informativas y donde los internos a la empresa disponen de información privada sobre la marcha de la empresa. La relevancia de la nueva información transmitida por la señal de los dividendos modificará las expectativas que sobre el valor de las acciones tienen los inversores externos, en el caso de que esta información sea significativa y no haya sido descontada con anterioridad. Una vez que hemos expuesto el estado de la cuestión, contrastamos empíricamente si los dividendos transmiten nueva información relevante. Para ello, el estudio se centra en el análisis de las reacciones de los precios de las acciones de la Bolsa de Madrid durante el período 1996-1997 ante anuncios de reparto de dividendos publicados por el Boletín de Cotización de la Bolsa de Madrid. Aplicamos la técnica del suceso para comprobar si existen rentabilidades anormales significativa en tomo a la fecha exdividendo y los períodos anterior y posterior al anuncio. Las peculiaridades informativas que presentan las empresas del sector bancario nos obliga a realizar el estudio por separado del resto de empresas. Los resultados obtenidos nos permiten confirmar las tesis de relevancia de la decisión de dividendos ya que se observa la existencia de rentabilidades anormales significativas en el período de publicación de los dividendos a cuenta, tanto en el sector bancario como en el resto de las empresas. Y con ello, podemos admitir la hipótesis del contenido informativo de los dividendos planteada por la teoría de la agencia y su carácter señalizador para los accionistas extemos sobre la situación de la empresa y su capacidad para generar nuevos fondos en el futuro.This research attempts to check the effect of dividend informative content in the Spanish Capital Market. The decisión of dividend delivery is one of the most controversial issue that becomes a big puzzle which pieces do not match with each other, as Black say

An Update on Autophagy in Prion Diseases

Autophagy is a dynamic intracellular mechanism involved in protein and organelle turnover through lysosomal degradation. When properly regulated, autophagy supports normal cellular and developmental processes, whereas defects in autophagic degradation have been associated with several pathologies, including prion diseases. Prion diseases, or transmissible spongiform encephalopathies (TSE), are a group of fatal neurodegenerative disorders characterized by the accumulation of the pathological misfolded isoform (PrPSc) of the physiological cellular prion protein (PrPc) in the central nervous system. Autophagic vacuoles have been described in experimental models of TSE and in the natural disease in humans. The precise connection of this process with prion-related neuropathology, or even whether autophagy is completely beneficial or pathogenic during neurodegeneration, is poorly understood. Thus, the biological role of autophagy in these diseases is still open to debate. During the last years, researchers have used a wide range of morphological, genetic and biochemical methods to monitor and manipulate the autophagic pathway and thus determine the specific role of this process in TSE. It has been suggested that PrPc could play a crucial role in modulating the autophagic pathway in neuronal cells, and the presence of abnormal autophagic activity has been frequently observed in several models of TSE both in vitro and in vivo, as well as in human prion diseases. Altogether, these findings suggest that autophagy is implicated in prion neuropathology and points to an impairment or failure of the process, potentially contributing to the pathogenesis of the disease. Additionally, autophagy is now emerging as a host defense response in controlling prion infection that plays a protective role by facilitating the clearance of aggregation-prone proteins accumulated within neurons. Since autophagy is one of the pathways of PrPSc degradation, and drug-induced stimulation of autophagic flux (the dynamic process of autophagic degradation activity) produces anti-prion effects, new treatments based on its activation have been tested to develop therapeutic strategies for prion diseases. In this review, we summarize previous and recent findings concerning the role of autophagy in TSE

Local Anomalies, Local Equivariant Cohomology and the Variational Bicomplex

The locality conditions for the vanishing of local anomalies in field theory are shown to admit a geometrical interpretation in terms of local equivariant cohomology, thus providing a method to deal with the problem of locality in the geometrical approaches to the study of local anomalies based on the Atiyah-Singer index theorem. The local cohomology is shown to be related to the cohomology of jet bundles by means of the variational bicomplex theory. Using these results and the techniques for the computation of the cohomology of invariant variational bicomplexes in terms of relative Gel'fand-Fuks cohomology introduced in [6], we obtain necessary and sufficient conditions for the cancellation of local gravitational and mixed anomalies.Comment: 36 pages. The paper is divided in two part

Transient Analysis of Fresnel Zone Plates for Ultrasound Focusing Applications

[EN] Fresnel Zone Plates are planar lenses that can be used to focus ultrasound beams. This kind of acoustic lenses can play a key role in the resolution of ultrasonic NDT systems. In this type of pulse-echo applications, the pulse duration is an important parameter that specifies the axial resolution, and thus, shorter ultrasound pulses provide higher resolutions. However, acoustic lenses exhibit a transient response that should be considered when setting the pulse duration, as pulses shorter than the transient state duration result in degradation in the response of acoustic lenses in terms of focal intensity, focal displacement, and lateral and axial resolutions. In this work, a thorough analysis of the transient response of Fresnel Zone Plates is discussed, demonstrating that the transient state should be considered in order to achieve optimal focusing performance. Theoretical and numerical results are presented, showing very good agreement.This work has been supported by Spanish MICINN RTI2018-100792-B-I00 project, Generalitat Valenciana AICO/2020/139 and the Russian Governmental program "Science" project FSWW-2020-0014. The research is carried out within the framework of Tomsk Polytechnic University Competitiveness Enhancement Program grant VIU-MNOL NK 187/2020. S.P.-L. acknowledges financial support from Universitat Politècnica de València grant program PAID-01-18. D.T.-S. acknowledges financial support from MICINN BES-2016-07713 project.Pérez-López, S.; Tarrazó-Serrano, D.; Dolmatov, DO.; Rubio Michavila, C.; Candelas Valiente, P. (2020). Transient Analysis of Fresnel Zone Plates for Ultrasound Focusing Applications. Sensors. 20(23):1-9. https://doi.org/10.3390/s20236824S192023Albu, S., Joyce, E., Paniwnyk, L., Lorimer, J. P., & Mason, T. J. (2004). Potential for the use of ultrasound in the extraction of antioxidants from Rosmarinus officinalis for the food and pharmaceutical industry. Ultrasonics Sonochemistry, 11(3-4), 261-265. doi:10.1016/j.ultsonch.2004.01.015Li, J.-T., Han, J.-F., Yang, J.-H., & Li, T.-S. (2003). An efficient synthesis of 3,4-dihydropyrimidin-2-ones catalyzed by NH2SO3H under ultrasound irradiation. Ultrasonics Sonochemistry, 10(3), 119-122. doi:10.1016/s1350-4177(03)00092-0McCann, D. ., & Forde, M. . (2001). Review of NDT methods in the assessment of concrete and masonry structures. NDT & E International, 34(2), 71-84. doi:10.1016/s0963-8695(00)00032-3Chen, J., Xiao, J., Lisevych, D., Shakouri, A., & Fan, Z. (2018). Deep-subwavelength control of acoustic waves in an ultra-compact metasurface lens. Nature Communications, 9(1). doi:10.1038/s41467-018-07315-6Thomas, J.-L., & Fink, M. A. (1996). Ultrasonic beam focusing through tissue inhomogeneities with a time reversal mirror: application to transskull therapy. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 43(6), 1122-1129. doi:10.1109/58.542055Melde, K., Mark, A. G., Qiu, T., & Fischer, P. (2016). Holograms for acoustics. Nature, 537(7621), 518-522. doi:10.1038/nature19755Castiñeira-Ibáñez, S., Tarrazó-Serrano, D., Fuster, J., Candelas, P., & Rubio, C. (2018). Polyadic Cantor Fractal Ultrasonic Lenses: Design and Characterization. Applied Sciences, 8(8), 1389. doi:10.3390/app8081389Rubio, C., Fuster, J., Castiñeira-Ibáñez, S., Uris, A., Belmar, F., & Candelas, P. (2017). Pinhole Zone Plate Lens for Ultrasound Focusing. Sensors, 17(7), 1690. doi:10.3390/s17071690Zhou, Q., Xu, Z., & Liu, X. (2019). High efficiency acoustic Fresnel lens. Journal of Physics D: Applied Physics, 53(6), 065302. doi:10.1088/1361-6463/ab5878Schindel, D. W., Bashford, A. G., & Hutchins, D. A. (1997). Focussing of ultrasonic waves in air using a micromachined Fresnel zone-plate. Ultrasonics, 35(4), 275-285. doi:10.1016/s0041-624x(97)00011-5Calvo, D. C., Thangawng, A. L., Nicholas, M., & Layman, C. N. (2015). Thin Fresnel zone plate lenses for focusing underwater sound. Applied Physics Letters, 107(1), 014103. doi:10.1063/1.4926607Tarrazó-Serrano, D., Pérez-López, S., Candelas, P., Uris, A., & Rubio, C. (2019). Acoustic Focusing Enhancement In Fresnel Zone Plate Lenses. Scientific Reports, 9(1). doi:10.1038/s41598-019-43495-xSalazar, J., Turó, A., Chávez, J. A., Ortega, J. A., & García, M. J. (2000). Transducer resolution enhancement by combining different excitation pulses. Ultrasonics, 38(1-8), 145-150. doi:10.1016/s0041-624x(99)00177-8Salazar, J., Turo, A., Chavez, J. A., Ortega, J. A., & Garcia, M. J. (2003). High-power high-resolution pulser for air-coupled ultrasonic nde applications. IEEE Transactions on Instrumentation and Measurement, 52(6), 1792-1798. doi:10.1109/tim.2003.820445Oelze, M. (2007). Bandwidth and resolution enhancement through pulse compression. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 54(4), 768-781. doi:10.1109/tuffc.2007.310Konovalov, S. I., & Kuz’menko, A. G. (2015). On the optimization of the shapes of short-duration acoustic pulses for solving probing problems in immersion tests. Russian Journal of Nondestructive Testing, 51(2), 101-107. doi:10.1134/s106183091502005

Influencia de factores productivos de cabras de raza Florida, en los resultados de fertilidad a inseminación artificial

Este estudio se ha realizado utilizando los datos recogidos por los técnicos de ACRIFLOR y del Centro IFAPA de Hinojosa del Duque durante las anualidades 2005, 2006, 2007 y 2008. Dichos datos informan acerca de la inseminación de 1.739 cabras de la raza Florida. El trabajo se ha realizado con semen fresco refrigerado, estudiando los siguientes factores: Número de parto de la cabra en el momento inseminación, Nivel de producción (kg de leche en el control lechero más cercano) y días de lactación desde la fecha del último parto. La obtención y procesamiento del semen se realiza por técnicos del Instituto Andaluz de Investigación y Formación Agraria, Pesca, Alimentación y de la Producción Ecológica IFAPA en el centro de Recogida de Esperma Caprino ubicado en Hinojosa del Duque (Córdoba), y donde ACRIFLOR, mediante Convenio suscrito con el IFAPA, mantiene su Centro de Testaje de Machos. Las hembras inseminadas deben cumplir los requisitos de: una ecografía previa para descartar las pseudogestaciones, que no hayan abortado o presenten problemas reproductivos, que no sean nulíparas y, además, todas las cabras deben estar identificadas individualmente y en control lechero oficial. Los resultados de fertilidad con inseminación artificial en la raza Florida no han sido tan altos como los resultados obtenidos en otras razas caprinas, los cuales rondan un 60% de fertilidad en semen fresco y un 50% de fertilidad en semen congelado, es por ello que se han analizado los posibles factores que pueden estar provocando estos resultados menos favorables