1,972 research outputs found

    Evaluating shoreline identification using optical satellite images

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    A technique to extract the shoreline location from optical satellite images has been developed and evaluated for the case study site of Progreso, Yucatán, México. A novel method to extract a satellite-derived shoreline (SDS) was developed ensuring the maximum contrast between sea and land. The area under investigation is an 8. km length of shoreline that faces north into the Gulf of México.The SDS was validated using quasi-simultaneous in situ shoreline measurements, both adjusted to equal water levels. In situ shoreline measurements recorded the instantaneous shoreward extent of the wave run-up when walking along the beach.The validation of SDS revealed that the SDS is located consistently seawards of the in situ shoreline, explained by: a) the water depth that optical satellite image requires to identify a pixel either as sea or land, and b) the shoreward extent of the wave run-up. The overall distance between SDS and in situ shoreline is 5.6. m on average with a standard deviation of 1.37. m (in the horizontal) over 8. km of shoreline. Confidence bounds considering the shoreward extent of the wave run-up, inter-tidal beach slope variation and tidal uncertainty were computed to assess the accuracy of the SDS.The SDS has been shown to be capable of detecting shoreline changes of less than 10. m and abrupt changes due to storms. The success of our method suggests that it should be applicable to other locations, after adapting the confidence bounds to the beach conditions

    First-Principle Description of Correlation Effects in Layered Materials

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    We present a first-principles description of anisotropic materials characterized by having both weak (dispersion-like) and strong covalent bonds, based on the Adiabatic--Connection Fluctuation--Dissipation Theorem within Density Functional Theory. For hexagonal boron nitride the in-plane and out of plane bonding as well as vibrational dynamics are well described both at equilibrium and when the layers are pulled apart. Also bonding in covalent and ionic solids is described. The formalism allows to ping-down the deficiencies of common exchange-correlation functionals and provides insight towards the inclusion of dispersion interactions into the correlation functional.Comment: Accepted for publication in Physical Review Letter

    IDENTIFICACIÓN MOLECULAR y FILOGENÉTICA DE ROTAVIRUS., EN CONEJOS DE LA ZONA SUR ORIENTE DEL ESTADO DE MÉXICO

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    Rotavirus es reconocido como el agente etiológico de gastroenteritis más importante tanto en niños como en animales neonatos en todo el mundo, con una morbilidad y mortalidad de gran impacto social y económico (Dodet et al., 1997; Estes et al., 2001; Matthijinssens et al., 2008). El género Rotavirus está clasificado dentro de la familia Reoviridae, subfamilia Sedoreovirinae (Nakagomi y Nakagomi, 2002). El genoma del virus está compuesto por 11 segmentos de doble cadena de RNA, seis de ellos codifican para seis proteínas estructurales (VP1-VP4, VP6 y VP7) y cinco para seis proteínas no estructurales (NSP1-NSP6). El genoma está protegido por una cápside constituida por tres capas (Martella et al., 2005). La capa intermedia está conformada en su totalidad por la proteína VP6, esta proteína permite la clasificación antigénica de rotavirus en siete grupos (A-G), aunque Matthijnssens et al., 2012, han añadido el grupo H. En conejos se ha identificado el grupo A de Rotavirus, las cepas que pertenecen a este grupo, se clasifican en subgrupos (SG), mediante la amplificación de la región que codifica para sus determinantes antigénicos, ubicada dentro del fragmento VP6En otros países, Rotavirus es considerado la principal etiología de gastroenteritis aguda en conejos. En México, en las unidades de producción cunícola los cuadros entéricos repercuten en alta mortalidad y fuertes pérdidas económicas. La proteína VP6 de la capa intermedia de la cápside del virus, es utilizada para clasificar antigénicamente el Rotavirus en grupos (A-H). Utilizando la técnica de Reverso Transcriptasa-Reacción en Cadena de la Polimerasa, se probaron 19 muestras de intestino de conejos sanos y con cuadro clínico entérico, provenientes de la región suroriente del Estado de México, De las muestras probada el 31.5% (6), amplificaron un fragmento de 380pb utilizando los primers específicos para el fragmento VP6. Es el primer reporte de detección molecular de Rotavirus en conejos en Méxic

    Combination of X-ray crystallography, SAXS and DEER to obtain the structure of the FnIII-3,4 domains of integrin a6b4

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    Integrin alpha6beta4 is a major component of hemidesmosomes that mediate the stable anchorage of epithelial cells to the underlying basement membrane. Integrin alpha6beta4 has also been implicated in cell proliferation and migration and in carcinoma progression. The third and fourth fibronectin type III domains (FnIII-3,4) of integrin beta4 mediate binding to the hemidesmosomal proteins BPAG1e and BPAG2, and participate in signalling. Here, it is demonstrated that X-ray crystallography, small-angle X-ray scattering and double electron– electron resonance (DEER) complement each other to solve the structure of the FnIII-3,4 region. The crystal structures of the individual FnIII-3 and FnIII-4 domains were solved and the relative arrangement of the FnIII domains was elucidated by combining DEER with site-directed spin labelling. Multiple structures of the interdomain linker were modelled by Monte Carlo methods complying with DEER constraints, and the final structures were selected against experimental scattering data. FnIII-3,4 has a compact and cambered flat structure with an evolutionary conserved surface that is likely to correspond to a protein-interaction site. Finally, this hybrid method is of general application for the study of other macromolecules and complexes

    Evaluación del comportamiento mecánico de capas bituminosas ultra delgadas como una adecuada estrategia para la rehabilitación de pavimentos urbanos

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    Very Thin Asphalt Overlay (VTAO) has been introduced as an alternative to traditional thick overlays, seal coats, and micro-surfacings. Nonetheless, there are some challenges that still remain regarding the application of VTAOs (such as mixture type, cohesiveness, wear resistance, cracking and durability), particularly in heavy traffic urban areas. Therefore, this paper presents an extensive comparative evaluation of the mechanical performance, durability and safety issues (cohesiveness, adhesiveness, ageing, cracking, plastic deformation, permeability, macrotexture, skid and wear resistance, and fuel resistance) of a VTAO (20 mm thick) and a high performance BBTM 11B (35 mm thick), commonly used as an open-graded mixture for pavement overlays. The results demonstrated that VTAO is an appropriate material for urban pavements as it provides good durability and resistance to the propagation of defects. Nonetheless, further studies are required to improve its behavior under distresses related to plastic deformations and safety properties.Las capas bituminosas ultra delgadas para rehabilitación superficial de carreteras son una alternativa a las tradicionales capas asfálticas, riegos bituminosos y micro-aglomerados. No obstante, aún son numerosos los aspectos a estudiar para la generalización de su uso, particularmente en zonas urbanas con elevado tráfico. Así, este artículo recoge un análisis comparativo del comportamiento mecánico, durabilidad y factores de seguridad (evaluando parámetros como cohesividad, adhevisvidad, envejecimiento, fisuración, deformaciones, permeabilidad, macrotextura, y resistencia al deslizamiento, al desgaste y a los combustibles) entre una capa delgada de 20 mm de espesor, y una mezcla discontinua de altas prestaciones (BBTM-11B con 35 mm), comúnmente utilizada en capas de rodadura. Los resultados indican que puede ser una adecuada solución para pavimentos urbanos dada su durabilidad y resistencia a la propagación de fallos. No obstante, se requieren futuros estudios centrados en la mejora de parámetros de seguridad y de su resistencia a las deformaciones permanentes

    Studies for the application of an adaptative controller to hydroturbine generators

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    This paper describes some studies made towards the automatization of hydroturbine generators with microcomputers. The overall design will include an automata controlling the starting-up and shutting-down procedure as well as an self-tuning regulator for the speed control. A self-tuning regulator based on the classical pole-assignment-method is studied. The algorithm uses a fast procedure for solving the polynomial equation implicit to selfturner regulator. This procedure is very simple from a computational point of view as only applications of elementary transformations on a 2 x 2 polynomial matrix are needed.The algorithm has been programmed on a Digital PDP 1103 computer and applied to some test problems

    Comparación del efecto de la concentración de polvo de neumático reciclado y polímeros en el comportamiento de ligantes para mezclas bituminosas

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    Crumb rubber modified binders are environmental-friendly alternatives to polymer modified bitumens in asphalt mixtures. This paper compares the performance of both types of binders with different modifier contents. Six binders were characterised by conventional tests and analysed using the UCL method. This method evaluates different properties of binders regarding their role in asphalt mixtures (cohesion, water and thermal sensitivity and resistance to ageing). Results showed that i) crumb rubber concentration has to be higher than that of SBS-polymers in order to obtain a similar performance to that of SBS-polymer modified bitumen; ii) crumb rubber modified binders are more stable than SBS-polymer modified binders in terms of modifier concentration; iii) crumb rubber modified binders exhibited less water sensitivity and similar thermal and ageing susceptibility to SBS-polymer modified binders; iv) linear relationships have been found between modifier concentration and the properties studied for both kind of binders.Los betunes modificados con polvo de neumático (PN) son alternativas ambientalmente sostenibles a los betunes modificados con polímeros. Este artículo compara el comportamiento de ambos tipos de betunes con varios contenidos de modificador. Para ello, se caracterizaron seis betunes mediante ensayos convencionales y método UCL. Este método evalúa propiedades de ligantes para su uso en mezclas bituminosas (cohesión, sensibilidad al agua, térmica y al envejecimiento). Los resultados muestran que i) la concentración de PN ha de ser más elevada que la de polímeros para obtener comportamiento semejante; ii) los betunes con PN son más estables ante cambios en la concentración de modificador que los betunes con polímeros; iii) los betunes con PN presentan menor sensibilidad al agua y equivalente susceptibilidad térmica y al envejecimiento que los betunes con polímeros; iv) se encontraron buenos ajustes lineales entre la concentración de modificadores y la evolución de las propiedades estudiadas

    Joint strengthening by external bars on RC beam-column joints

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    [EN] Column strengthening is a very common practice for improving the seismic performance of reinforced concrete frame structures or repairing damage after a seismic event. Several methods are employed for column strengthening, which can improve column strength by preventing its shear, bending or compression failure. However, not all methods allow column strengthening connections between adjacent floors, thus the beam-column joint strength could be limited by the column-joint interface capacity. This work aimed to analyse two joint strengthening designs, for which an experimental campaign of eight full-scale beam-column joints strengthened with steel caging, and subjected to cyclic and gravity loads, was carried out. As access to joint panels is very complex in existing structures, joint strengthening consists of external solutions: vertical or diagonal bars and capitals connecting columns. The results showed that these techniques significantly increased beam-column joint strength and highlighted that failure can be undesirably transferred to the joint. Vertical bars prevented the bending failure of the column-joint interface, but failure occurred at the joint in this study. Diagonal bars can also prevent joint failure.The authors wish to thank the financial support provided by the Spanish Ministry of Science and Innovation and the Spanish Ministry of Economy and Competitiveness with Research Projects BIA 2008-06268 and RTI2018-099091-B-C22.Ruiz Pinilla, JG.; Cladera, A.; Pallarés Rubio, FJ.; Calderón García, PA.; Adam, JM. (2022). Joint strengthening by external bars on RC beam-column joints. Journal of Building Engineering. 45:1-14. https://doi.org/10.1016/j.jobe.2021.1034451144
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