1,092 research outputs found
Noisy Environments: the Influence on Basic Cognitive Processes
The attention processes in people is affected by background noise produced by many different sources. Beta (13-30Hz) and Theta (4-7 Hz) waves are directly related to attention and memory processes. Volunteers were asked to perform an attention test with and without background noise and their cerebral activity was recorded through electroencephalography (EEG). Results shows significant decreases in both beta and theta frequency bands (beta 13-30 Hz and theta 4-7 Hz) under background noise exposure. The attentional improvement is related to increases of the beta and theta waves, and we have observed that those decreases are directly related to a lack of attention caused by the exposure to background noise
Condroblastoma de astrágalo: localización inusual
Se expone 1 caso de un condroblastoma de astrágalo en 1 paciente de 17 años.
Esta tumoración, definida como tal en 1942 por Jaffe y Lichtenstein, presenta un comportamiento
benigno que responde al tratamiento mediante curetaje e injerto óseo de la cavidad. A pesar de
este comportamiento benigno se hace mención a la posibilidad de metástasis pulmonares y a la
agresividad local en algunos casos.A 17-year-old man with chondroblastoma of the talus is reported. This tumor described
in 1942 by Jaffe and Lichtenstein has a benign behavior and a good response to surgical
treatment by curetage of the cavity and bone graft. In certain cases local aggresivity and lung metastasis
has been described
A phenomenological explanation of the autoignition propagation under HCCI conditions
[EN] A phenomenological explanation about the autoignition propagation under HCCI conditions is developed in this paper. To do so, diffusive effects from the burned zones to the fresh mixture, pressure waves based effects and expansion effects caused by combustion are taken into account. Additionally, different Damkohler numbers have been defined and evaluated in order to characterize the phenomenon and quantify the relevance of each effect. The theoretical explanation has been evaluated by means of chemiluminescence measurements performed in a Rapid Compression Expansion Machine (RCEM), which allow to estimate the velocity of propagation of the autoignition front. The results showed that under HCCI conditions the autoignition propagation is controlled, in general, by the pressure waves established in the combustion chamber, since the characteristic time of the autoignition propagation is too short to assume the absence of pressure gradients in the chamber. Thus, the thermodynamic conditions reached behind the pressure wave promote the autoignition and explain the high propagation velocities associated to the reaction front. Besides, the results also showed that the contribution of diffusive phenomena on the propagation is negligible, since the characteristic time of diffusion is too long compared to the characteristic time of the autoignition propagation. Finally, the experimental measurements showed that the autoignition propagation is affected by a really relevant cycle-to-cycle variation. The turbulence generated by the combustion has, by definition, an aleatory behavior, leading to random heterogeneity distribution and, therefore, to somewhat random autoignition propagation.The authors would like to thank different members of the CMT-Motores TTrmicos team of the Universitat Politecnica de Valencia for their contribution to this work. The authors would also like to thank the Spanish Ministry of Education for financing the PhD. Studies of Dario Lopez-Pintor (grant FPU13/02329). This research has been partially funded by FEDER and the Spanish Government through project TRA2015-67136-R.Desantes, J.; López, JJ.; García-Oliver, JM.; López-Pintor, D. (2017). A phenomenological explanation of the autoignition propagation under HCCI conditions. Fuel. 206:43-57. https://doi.org/10.1016/j.fuel.2017.05.075S435720
Experimental validation and analysis of seven different chemical kinetic mechanisms for n-dodecane using a Rapid Compression-Expansion Machine
[EN] Seven different chemical kinetic mechanisms for n-dodecane, two detailed and five reduced, have been evaluated under Engine Combustion Network (ECN) thermodynamic conditions by comparison to experimental measurements in a Rapid Compression-Expansion Machine (RCEM). The target ECN conditions are imposed at Top Dead Center (TDC), which cover a wide range of temperatures (from 850 K to 1000 K), oxygen molar fractions (0.21 and 0.15) and equivalence ratios (0.8, 0.9 and 1), while the pressure is fixed to keep a constant density at TDC equal to 22.8 kg/m(3). The results obtained have been used to validate the chemical kinetic simulations, which have been performed with CHEMKIN, by comparing both cool flames and high temperature ignition delays, as well as the heat released in each stage of the combustion process in case of having a two-stage ignition pattern. The experimental results show good agreement with the chemical kinetic simulations. In fact, the mean relative deviation in ignition delay between experiments and simulations among all the chemical mechanisms is equal to 18.0% (3 CAD) for both cool flames and high temperature ignition. In general, closer correspondence has been obtained for the ignition delay referred to the high-temperature stage of the process, being the cool flames phenomenon more difficult to reproduce. Moreover, the differences between the reduced mechanisms and the most detailed one have been analyzed, concluding that the enhanced specific reaction rates of the most reduced mechanisms cause differences not only on the ignition delays, but also on the Negative Temperature Coefficient (NTC) behavior and on the heat released during cool flames. (C) 2017 The Combustion Institute. Published by Elsevier Inc. All rights reserved.The authors would also like to thank the Spanish Ministry of Education for financing the PhD. Studies of Dario Lopez-Pintor (grant FPU13/02329). This study was partially funded by the Spanish Ministry of Economy and Competitiveness in the frame of the COMEFF (TRA2014-59483-R) project.Desantes, J.; López, JJ.; García-Oliver, JM.; López-Pintor, D. (2017). Experimental validation and analysis of seven different chemical kinetic mechanisms for n-dodecane using a Rapid Compression-Expansion Machine. Combustion and Flame. 182:76-89. https://doi.org/10.1016/j.combustflame.2017.04.004S768918
Algunos datos nuevos sobre las relaciones Iglesia-Estado durante la Segunda República Española. Documentación inédita del Nuncio Tedeschini en el Archivo Secreto Vaticano
Se pretende mostrar la importancia que para el estudio y la investigación de las relaciones entre la Iglesia católica y la Segunda República tendrán los fondos puestos a consulta recientemente en el Archivo Secreto Vaticano. Se han seleccionado dos momentos de especial trascendencia. En primer lugar, la proclamación de la Segunda República. Los telegramas cifrados cruzados ente la Secretaría de Estado y Tedeschini, aportan datos no conocidos y de bastante relieve. En segundo lugar la aprobación por las Cortes, del que habría de ser el artículo 26 de la Constitución de 1931. En un extenso informe (que se transcribe íntegramente) el Nuncio Tedeschini relata cómo fueron los acontecimientos. Los testimonios históricos sobre la existencia (Alcalá-Zamora) o no (Azaña) de un acuerdo entre el Gobierno provisional y la jerarquía eclesiástica, eran contradictorios. Este nuevo testimonio corrobora su existencia: el Nuncio no duda en hablar de traición, refiriéndose en especial a Azaña. ------ It aims to show the importance of the collections recently available in the Vatican Secret Archive for the study and investigation of the relations between the Catholic Church and the Second Republic. Two moments of special transcendence have been selected. First is the proclamation of the Second Republic. The encoded telegrams exchanged between tge Secretary of State and Tedeschini offer unknown data of quite relevance. Second is the approval by the 'Cortes', of which the article 26 of the Constitution of 1931 would have been. In an extensive report (which is transcribed completely), Nuncio Tedeschini relates how the events were. The historical testimonies about the existence (Alcalá-Zamora) or non-existence (Azaña) of an agreement between the provisional government and the ecclesiastical hierarchy were contradictories. This new testimony corroborates its existence: the Nuncio does not doubt in speaking about betrayal, specially referring to Azaña
Gases Separation by ZSM-5 based Membranes
AbstractPresent work analyses the effect produced by the presence of ZSM-5 zeolite in an alumina tube upon the permeation rate of different gases (nitrogen, oxygen, carbon dioxide and normal-butane). A comparison between experimental data of permeation through the membrane with and without ZSM-5 zeolite was performed with an increase in the resistance to transport more evident for n-butane. Also the influence of temperature upon permeation has been analyzed
Orbital cycles, differential subsidence and internal factors controlling the high-frequency sequence architecture in a Sinemurian shallow carbonate platform (Mallorca island, Spain)
The ~125 m thick lower to lowermost upper Sinemurian peritidal to shallow subtidal platform carbonates in the Llevant Mountains of Mallorca (Spain) have been analysed from four stratigraphic sections, to provide new data on the hierarchical stacking pattern of high-frequency depositional sequences. Due to the fact that in shallow water environments the stacking of carbonate facies can be controlled by external (allocyclic) and internal (autocyclic) processes, deciphering the dominant controls on the high-frequency sequence architecture of these platforms is a challenge. The studied carbonates encompass a high variety of facies representative of open lagoon, internal bars, restricted lagoon and tidal flats with local beach sands. Based on a detailed analysis of vertical facies trends and bounding surfaces, large-, medium- and small-scale sequences have been identified within the long-term transgressive-regressive facies cycle defined by the entire succession. Large-scale sequences (~10–30 m thick) and medium-scale sequences (~1–10 m thick) are generally shallowing-upward sequences bounded by sharp facies changes to relatively deeper facies, and have been related to sea-level variations driven by long- (~400 kyr) and short- (~100 kyr) eccentricity cycles respectively. The overprinting of differential subsidence (probably related to extensional tectonic) and carbonate production and accumulation processes varied throughout time, controlling the lateral continuity and preservation potential of the ~100 kyr medium-scale sequences. Shallowing-upward, locally aggradational, small-scale sequences (~0.3 to 5 m thick) are very variable in number and thickness and cannot be correlated between sections, pointing out that their most important controlling factor was the internal processes (hiatuses and erosion related to subaerial exposure at the peritidal caps, lateral migration of internal bars, local wave and currents patterns, depositional and erosional processes related to spring tides and storms) in the frame of a complex mosaic of facies within the studied platform
Luxación radiocarpiana con fractura asociada de la apófisis estiloides radial
Presentamos un caso de luxación dorso lateral del carpo con fractura asociada
de la estiloides radial en una mujer de 28 años tras accidente de tráfico. No existieron
complicaciones neurovasculares. El tratamiento consistió en reducción y fijación
de la estiloides radial con agujas de Kirschner. Después de seis meses de evolución la paciente
estaba libre de secuelas
El uso de imágenes Ikonos para la cartografía de riesgo de inundación en pequeñas cuencas mediterráneas
La confección de una cartografía efectiva de riesgo de inundación precisa de la elaboración previa de mapas de peligro, que recojan las zonas sometidas a los procesos naturales asociados a la crecida. Para la configuración de estos mapas resulta muy útil el estudio de las áreas afectadas en sucesos concretos. En esta tarea el uso de la teledetección se ha demostrado altamente eficaz para el caso de grandes cuencas, afectadas por procesos de inundación extensivos y llanuras bien definidas. Sin embargo, para el caso de pequeñas cuencas mediterráneas, donde los espacios inundables son de índole muy variada, pequeña dimensión y rápido drenaje, el uso de las imágenes de satélite no siempre ha sido eficaz.
La comercialización, en los último años, de imágenes de muy alta resolución (Ikonos, Quickbird) constituye una alternativa viable para la detección de las zonas afectadas en pequeñas cuencas. El presente trabajo constituye un ejemplo de uso de una imagen Ikonos para el análisis de las zonas inundadas durante el suceso de octubre del año 2000 en la Rambla de Poyo - Barranc de Torrent. Esta cuenca tiene una dimensión de 462 km2 , desemboca en la Albufera y presenta varias zonas inundables que afectan al área metropolitana de Valencia. Durante el suceso de octubre del 2000, tuvo lugar una crecida de más de 500 m3/s que dio lugar a diversos problemas de inundación, referenciados, en su día, mediante trabajo de campo y fotografía oblícua. El análisis visual de la imagen IKONOS permite establecer, de una manera rápida y completa, la extensión de la zona inundada, así como inferir los principales procesos de rotura en cauce, derrame y desbordamiento, asociados a la crecida
The influence of recycled aggregates from precast elements on the mechanical properties of structural self-compacting concrete
Recycled Aggregates (RA) from structural precast elements and the performance of Self-Compacting Concrete (SCC) containing RA in percentage substitutions of 20%, 50% and 100% are described in this paper. Three Control Concretes (CC-30, CC-37.5, CC-45) manufactured with Natural Aggregates (NA), and their corresponding Recycled Aggregate Concretes (RAC-20, RAC-50, RAC-100) are evaluated in terms of physical and mechanical properties. The in-fresh properties results (flowability, viscosity and passing ability) of the RAC were suitable for their use as SSC. Furthermore, the tests of compressive, splitting tensile and flexural strength, as well as density, porosity, water absorption, ultrasonic pulse velocity, stiffness, and both dynamic and static modulus provided results close to those of the SCC with NA, and in compliance with the requirements of current regulations. The recycling process that takes place in the precast factory supposes an economical improvement and an important contribution to global sustainability, in accordance with the concept of the circular economy.The authors wish to express their gratitude for having contributed to the financing of this research to: Junta de Castilla y León (Regional Government) for funding UIC-231 through project BU119P17; MINECO for funding through project BIA2014-55576-C2-1-R; and FEDER (European Regional Development Funds).
Moreover, we are grateful to the precast concrete company Artepref for having collaborated with the present research work
- …