741 research outputs found

    Non-equilibrium Effects in the Thermal Switching of Underdamped Josephson Junctions

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    We study the thermal escape problem in the low damping limit. We find that finiteness of the barrier is crucial for explaining the thermal activation results. In this regime low barrier non-equilibrium corrections to the usual theories become necessary. We propose a simple theoretical extension accounting for these non-equilibrium processes which agrees numerical results. We apply our theory to the understanding of switching current curves in underdamped Josephson junctions.Comment: 4 pages + 4 figure

    Volcanisme, tectonique et réseau hydrographique sur le piémont andin du désert du nord du Chili

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    À partir d'une photographie aérienne verticale, remarquable par les anomalies qu'elle fait apparaître dans le tracé du réseau hydrographique, on peut retracer les principales étapes de l'évolution du piémont andin dans le désert du Nord du Chili pendant le Cénozoïque supérieur : 1) puissante accumulation volcano-détritique au Miocène inférieur et moyen, conséquence du soulèvement des Andes à la fin de l'Oligocène; 2) glaciplanation au Miocène supérieur; 3) incision des cours d'eau, perturbée par des mouvements tectoniques importants au Pliocène; 4) changements climatiques, caractérisés par des atténuations passagères de l'aridité, à l'origine de différentes générations de dépôts détritiques au Pliocène et au Quaternaire.From a vertical aerial photograph, noteworthy for anomalies which characterize the hydrographic network of the depicted area, are deduced the main stages of the Andean piedmont evolution in the desert of northernmost Chile during the Upper Cenozoic: 1) as a consequence of the uplift of the Andes at the end of the Oligocène, thick accumulation of continental sediments and ignimbritic lava flows during the Lower and Middle Miocene; 2) development of a planation surface of pediment type in the Late Miocene; 3) channel incision, disturbed by important tectonic movements in the Pliocene; 4) climatic changes, marked by increased precipitation, generating several generations of clastic deposits in the Pliocene and the Quaternary.Una fotografia aérea vertical, notable por las anomalias que aparecen en Ia red hidrografica, permite aclarar las principales etapas de la evolucion del pedemonte andino del Norte Grande chileno durante el Cenozoico superior: 1) potente acumulacion volecanica y detritica en el Mioceno inferior y medio, como consecuencia del solevantamiento de los Andes a fines del Oligoceno; 2) pediplanacion en el Mioceno superior; 3) encajonamiento de los cursos de agua, perturbado por importantes movimientos tectônicos en el Plioceno; 4) cambios climaticos, caracterizados por una atenuacion de la aridez, que producen varias generaciones de depositos detriticos en el Plioceno y el Cuaternario

    Specification and Development of a HMI for ADAS, Based in Usability and Accessibility Principles

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    Traditionally, the design of road vehicle HMI is based in esthetic principles, maintaining it as an attractive factor for possible clients when buying a car. Only recently, ergonomic benefits have been applied to the design of HMIs, mainly following institutional impulses like the European Union one, but whose contribution is not clearly stated nowadays in commercial products. In this paper the authors present a study of the design of an HMI, based in usability and accessibility premises, centering the design in the user, as method to improve safety, making natural the communication with the driver as well as being able to transmitting information to the driver, from basic to the generated by ADAS installed in the car. Following these specifications a set of prototypes have been designed in order to develop a testbed that could be evaluated for a large set of drivers.This work has been supported by the Spanish Ministry of Science and Innovation (TRA2007-67786 and TRA2009-07505) and the CAM project SEGVAUTO-II.Publicad

    The DREAM–DRE interaction: key nucleotides and dominant negative mutants

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    AbstractTranscriptional repressor DREAM, an EF-hand containing calcium-binding protein, blocks basal expression of target genes through specific interaction with DRE sites in the DNA. The sequence GTCA forms the central core of the DRE site, whereas flanking nucleotides contribute notably to the affinity for DREAM. Release of binding of DREAM from the DRE results in derepression, a process that is regulated by Ca2+. Change of two amino acids within an EF-hand in DREAM blocks Ca2+-induced derepression and results in potent dominant negative mutants of endogenous DREAM

    Compositional variability in mafic arc magmas over short spatial and temporal scales: evidence for the signature of mantle reactive melt channels

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    Understanding arc magma genesis is critical to deciphering the construction of continental crust, understanding the relationship between plutonic and volcanic rocks, and for assessing volcanic hazards. Arc magma genesis is complex. Interpreting the underlying causes of major and trace element diversity in erupted magmas is challenging and often non-unique. To navigate this complexity mafic magma diversity is investigated using sample suites that span short temporal and spatial scales. These constraints allow us to evaluate models of arc magma genesis and their geochemical implications based on physical arguments and recent model results. Young volcanic deposits (≲18 kyr) are analysed from the Southern Volcanic Zone (SVZ), Chile, in particular suites of scoria cones on the flanks of arc stratovolcanoes that have erupted relatively primitive magmas of diverse compositions. Our study is centred on the high-resolution post-glacial tephrochronological record for Mocho-Choshuenco volcano where tight age constraints and a high density of scoria cones provide a spatially well-resolved mafic magma dataset. Two compositional trends emerge from the data. Firstly, magmas from cones on the flanks of the main edifice become more mafic with distance from the central vent. This is attributed to fractional crystallisation processes within the crust, with distal cones sampling less differentiated magmas. Secondly, there is a set of cones with distinct major and trace element compositions that are more primitive but enriched in incompatible elements relative to the central system and other ‘normal SVZ’ magmas. This distinct signature – termed the ‘Kangechi’ signature – is observed at three further clusters of cones within the SVZ. This is attributed to greater preservation of the enriched melt signature arising from reactive melt transport within the mantle wedge. Our model has important implications for arc magma genesis in general, and in particular for the spatial and temporal scales over which compositional variations are preserved in erupted magmas

    A Study of PLA Thin Film on SS 316L Coronary Stents Using a Dip Coating Technique

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    The dip coating process is one of the recognized techniques used to generate polymeric coatings on stents in an easy and low-cost way. However, there is a lack of information about the influence of the process parameters of this technique on complex geometries such as stents. This paper studies the dip coating process parameters used to provide a uniform coating of PLA with a 4–10 µm thickness. A stainless-steel tube (AISI 316L) was laser-cut, electropolished, and dip-coated in a polylactic acid (PLA) solution whilst changing the process parameters. The samples were characterized to examine the coating’s uniformity, thickness, surface roughness, weight, and chemical composition. FTIR and Raman investigations indicated the presence of PLA on the stent’s surface, the chemical stability of PLA during the coating process, and the absence of residual chloroform in the coatings. Additionally, the water contact angle was measured to determine the hydrophilicity of the coating. Our results indicate that, when using entry and withdrawal speeds of 500 mm min−1 and a 15 s immersion time, a uniform coating thickness was achieved throughout the tube and in the stent with an average thickness of 7.8 µm.We gratefully thank Consejo Nacional de Humanidades, Ciencia y Tecnología (Conahcyt) (CVU: 931068) and Tecnologico de Monterrey for providing scholarship and tuition to the lead author of the Ph.D. degree program. We thank Ciencia de Frontera Consejo Nacional de Humanidades, Ciencias y Tecnologías: CF-2023-I-2901. The Advanced Manufacturing research group (Tecnologico de Monterrey) supported the acquisition of materials. This research did not receive any other specific grant from funding agencies in the public, commercial, or not-for-profit sectors.Departamento de Ingeniería Química, Química Física y Ciencias de los Materiale

    Traffic signs recognition for detailed digital maps development and driver assistance systems

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    Digital maps are considered as an additional sensor in many of the new ADAS, but these systems usually require a higher level of accuracy and detail of the maps. Among the important information that the maps should contain are the road geometry and traffic signs. In the first case, it is interesting to use accurate and fast methods for measurement. In the paper, a method based on a datalog vehicle is used. Satellite positioning and inertial measurements systems data are combined and dynamic behavior of the vehicle body is corrected measuring the movements of the suspension system. On the other hand, the information provided by traffic signs and route-guidance signs is extremely important for safe and successful driving. An automatic system that is capable of extracting and identifying these signs automatically would help human drivers enormously; navigation would be easier, allowing them to concentrate on driving the vehicle. A Computer Vision System is used to recognize and classify the different families of traffic signs combining it with GPS information to develop detailed and accurate digital maps. This sign recognition can also be used for real time warnings to the driver. Some results of test carried out in real situations are shown

    NaRALap: augmented reality system for navigation in laparoscopic surgery

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    The final publication is available at Springer via http://dx.doi.org/10.1007/s11548-011-0579-z.The AR system has a good resolution and currently is used for the placement of the trocars. Possible improvements will be performed to make the system independent of the camera position or to use natural marks. The biomechanical model and the AR algorithms will be combined with a tracker, for tracking the surgical instruments, in order to implement a valid system for liver biopsies. It will take into account the deformation due to the pneumoperitoneum and due to the breath of the patient. To develop the navigator that will guide the laparoscopic interventions, both AR system and biomechanical model will be combined with the laparoscopic camera in order to make an easier environment with only one vision in a 2D monitor.This work has been supported by the project MITYC (ref. TSI020100-2009-189). We would like to express our deep gratitude to the Hospital Clínica Benidorm for its participation in this project.López-Mir, F.; Martínez Martínez, F.; Fuertes Cebrián, JJ.; Lago, MA.; Rupérez Moreno, MJ.; Naranjo Ornedo, V.; Monserrat Aranda, C. (2011). NaRALap: augmented reality system for navigation in laparoscopic surgery. International Journal of Computer Assisted Radiology and Surgery. 6:98-99. https://doi.org/10.0.3.239/s11548-011-0579-zS9899
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