370 research outputs found

    Uncertainty in the numerical modelling of masonry triplet tests under dynamic loading

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    Masonry structures have been broadly used worldwide for centuries. These structures are likely to be subjected to seismic movements, malicious or accidental blast and/or impact loading. Expanding the current body of knowledge of how masonry structures perform under such conditions and developing reliable and robust modelling techniques is essential to improve both the efficiency and safety of the design and retrofitting of such structures. A great deal of research is currently ongoing to understand the behaviour of masonry under shock and impact loading, and this is proving to be a challenging endeavour. Masonry construction on the whole is surrounded by a high degree of variability ranging from the heterogeneity of the materials used, the degree of workmanship during construction and the uncertainty regarding the physical and mechanical properties of the brick-to-mortar interface. Masonry is known to experience a dynamic enhancement of its strength properties when subjected to impact loading and dynamic increase factors (DIFs) have been used to adjust static masonry properties accordingly when subjected to this type of loading. These DIFs are derived from sparse experimental tests and their use can be severely limited to the conditions of the tests performed, and the results obtained can carry a high degree of uncertainty. This paper considers the uncertainty present at the brick-to-mortar interface, by using Monte Carlo simulations, when subjected to dynamic loading in a standard triplet test using LS-DYNA. The results of the modelling have been compared, contrasted and discussed for use in a larger research project on the robust characterisation of masonry structures when subjected to blast and seismic loadin

    Os roedores das ilhas Flores e Corvo : distribuição, fertilidade e morfometria

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    XIII Expedição Científica do Departamento de Biologia - Flores e Corvo 2007.O conhecimento da biologia e ecologia das espécies de roedores dos Açores é escasso. Integrado na XIII Expedição Científica do Departamento de Biologia da Universidade dos Açores, realizámos uma amostragem de roedores em três habitats distintos (pastagem, floresta e lixeira) na ilha das Flores, durante três noites, e num habitat (lixeira) na ilha do Corvo, durante uma noite. A espécie Mus musculus foi capturada nos três habitats, Rattus rattus foi capturada na floresta e na pastagem e Rattus norvegicus só foi capturada na lixeira. Na ilha do Corvo não conseguimos efectuar nenhuma captura de animais destas espécies. Apresentamos os dados da fertilidade potencial das fêmeas prenhas capturados e dados sobres as medidas de algumas características da morfologia externa. Sugerimos um padrão de distribuição das três espécies para o Arquipélago dos Açores e apresentamos uma forma simples e expedita para a identificação das espécies de Rodentia nos Açores

    The meridian incision : a technical modification in the conservative surgery of the impacted maxillary canine

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    We describe a technical modification of the apical repositioning flap in the conservative surgical treatment of the impacted canine in buccal position. This amendment improves the tooth?s eventual visualization, thus permitting a better evolutive follow-up of its eruption process and, most importantly, providing the tooth with buccal attached gingiva that will accompany it in its downward progression, procuring a cervical contour without retraction, a satisfactory esthetic outcome and a physiologically correct periodontal ridge. The traditional apical repositioning flap also bestows the canine with attached gingiva; however, since the flap is sutured apically and its width is significantly smaller than the remaining surgical defect, the wound?s closure is compromised at one of its edges and often requires healing by second intention at an undesired location next to the buccal sulcus. We believe the introduction of the meridian incision is a simple, expedient technical modification with efficient results

    Laser floating zone growth: Overview, singular materials, broad applications, and future perspectives

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    The Laser Floating Zone (LFZ) technique, also known as Laser-Heated Pedestal Growth (LHPG), has been developed throughout the last several decades as a simple, fast, and crucible-free method for growing high-crystalline-quality materials, particularly when compared to the more conventional Verneuil, Bridgman-Stockbarger, and Czochralski methods. Multiple worldwide efforts have, over the years, enabled the growth of highly oriented polycrystalline and single-crystal high-melting materials. This work attempted to critically review the most representative advancements in LFZ apparatus and experimental parameters that enable the growth of high-quality polycrystalline materials and single crystals, along with the most commonly produced materials and their relevant physical properties. Emphasis will be given to materials for photonics and optics, as well as for electrical applications, particularly superconducting and thermoelectric materials, and to the growth of metastable phases. Concomitantly, an analysis was carried out on how LFZ may contribute to further understanding equilibrium vs. non-equilibrium phase selectivity, as well as its potential to achieve or contribute to future developments in the growth of crystals for emerging applications

    Validation of Sentinel-3 SLSTR Land Surface Temperature Retrieved by the Operational Product and Comparison with Explicitly Emissivity-Dependent Algorithms

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    Land surface temperature (LST) is an essential climate variable (ECV) for monitoring the Earth climate system. To ensure accurate retrieval from satellite data, it is important to validate satellite derived LSTs and ensure that they are within the required accuracy and precision thresholds. An emissivity-dependent split-window algorithm with viewing angle dependence and two dual-angle algorithms are proposed for the Sentinel-3 SLSTR sensor. Furthermore, these algorithms are validated together with the Sentinel-3 SLSTR operational LST product as well as several emissivity-dependent split-window algorithms with in-situ data from a rice paddy site. The LST retrieval algorithms were validated over three different land covers: flooded soil, bare soil, and full vegetation cover. Ground measurements were performed with a wide band thermal infrared radiometer at a permanent station. The coefficients of the proposed split-window algorithm were estimated using the Cloudless Land Atmosphere Radiosounding (CLAR) database: for the three surface types an overall systematic uncertainty (median) of −0.4 K and a precision (robust standard deviation) 1.1 K were obtained. For the Sentinel-3A SLSTR operational LST product, a systematic uncertainty of 1.3 K and a precision of 1.3 K were obtained. A first evaluation of the Sentinel-3B SLSTR operational LST product was also performed: systematic uncertainty was 1.5 K and precision 1.2 K. The results obtained over the three land covers found at the rice paddy site show that the emissivity-dependent split-window algorithms, i.e., the ones proposed here as well as previously proposed algorithms without angular dependence, provide more accurate and precise LSTs than the current version of the operational SLSTR product

    On the Rees-Sciama effect: maps and statistics

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    Small maps of the Rees-Sciama (RS) effect are simulated by using an appropriate N-body code and a certain ray-tracing procedure. A method designed for the statistical analysis of cosmic microwave background (CMB) maps is applied to study the resulting simulations. These techniques, recently proposed --by our team-- to consider lens deformations of the CMB, are adapted to deal with the RS effect. This effect and the deviations from Gaussianity associated to it seem to be too small to be detected in the near future. This conclusion follows from our estimation of both the RS angular power spectrum and the RS reduced n-direction correlation functions for n<7.Comment: 11 pages, 13 figures, to appear in MNRA

    Label-free piezoelectric biosensor for prognosis and diagnosis of Systemic Lupus Erythematosus

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    [EN] An autoantigen piezoelectric sensor to quantify specific circulating autoantibodies in human serum is developed. The sensor consisted on a quartz crystal microbalance with dissipation monitoring (QCM-D) where TRIM21 and TROVE2 autoantigens were covalently immobilized, allowing the selective determination of autoantibodies for diagnosis and prognosis of Systemic Lupus Erythematosus (SLE). The sensitivity of the biosensor, measured as IC50 value, was 1.51 U/mL and 0.32 U/mL, for anti-TRIM21 and anti-TROVE2 circulating autoantibodies, respectively. The sensor is also able to establish a structural interaction fingerprint pattern or profile of circulating autoantibodies, what allows scoring accurately SLE patients. Furthermore, a statistical association of global disease activity with TRIM21-TROVE2 interaction was found (n=130 lupic patient samples, p-value=0.0413). The performances of the biosensor were compared with standard ELISA and multiplex DVD-array high-throughput screening assays, corroborating the viability of piezoelectric biosensor as a cost-effective in vitro assay for the early detection, monitoring or treatment of rare diseases.We acknowledge financial support from the Generalitat Valenciana (GVA-PROMETEOII/2014/040) as well as the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund under award numbers CTQ2013-45875-R and CTQ2013-42914-R.Do Nascimento, NM.; Juste-Dolz, A.; Grau-García, E.; Roman-Ivorra, JA.; Puchades, R.; Maquieira Catala, A.; Morais, S.... (2017). Label-free piezoelectric biosensor for prognosis and diagnosis of Systemic Lupus Erythematosus. Biosensors and Bioelectronics. 90:166-173. https://doi.org/10.1016/j.bios.2016.11.004S1661739

    Malformaciones venosas orofaciales de bajo flujo: esclerosis endoluminal con láser de diodo

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    ResumenIntroducciónLas anomalías vasculares son procesos frecuentes que se localizan en más del 50% de los casos en la región de la cabeza y el cuello. Las técnicas clásicas de tratamiento, tales como la cirugía y la esclerosis química, han dado paso a modernas técnicas menos invasivas, tales como el láser Nd:YAG. Por otra parte, se ha utilizado con éxito el láser de diodo (980 nm) para el tratamiento de varices mediante esclerosis endoluminal. Nuestra propuesta es la utilización del láser de diodo (λ 980 nm) para provocar una esclerosis por fotocoagulación intralesional de las malformaciones venosas de bajo flujo dada la capacidad de este láser de ser transmitido por fibra óptica.ObjetivoExponer nuestros resultados en el tratamiento de malformaciones venosas de bajo flujo (MVBF) orofaciales mediante la terapéutica de esclerosis endoluminal con láser de diodo.Material y métodosRevisamos 84 pacientes que presentaban MVBF orofaciales tratados con láser de diodo. Describimos la técnica de realización y se muestran los resultados postoperatorios a corto plazo.ResultadosTras un periodo de seguimiento no inferior a 12 meses se constató curación en el 95,24% aplicando una o dos sesiones y solamente en 4 casos se objetivó recidiva. Concluimos que la técnica de esclerosis endoluminal con láser de diodo de MVBF en el área orofacial se constituye como una nueva técnica de tratamiento, mínimamente invasiva, ambulatoria, y que permite la resolución de los casos sin tener que recurrir a cirugías más agresivas y con excelentes resultados funcionales y estéticos.AbstractBackgroundVascular anomalies are common processes that involve the head and neck region in more than 50% of the cases. Traditional treatment options such as surgery and chemical sclerosis have given way to modern less-invasive techniques, including Nd:YAG laser treatment. On the other hand, 980 nm laser diode has been successfully used for the endovenous sclerosis of varicose veins. Our proposal is the usage of diode laser (λ = 980 nm) to induce the sclerosis of low-flow venous malformations by intralesional photocoagulation, given this laser's ability to deliver the beam via a fiber optic cable.ObjectiveTo report our results in the treatment of orofacial low-flow venous malformations (LFVM) with diode laser endovenous sclerosis (DLES).Material and methods: The clinical records from 84 patients presenting with orofacial LFVM treated with DLES were collected. The technique used and short-term postoperative results were revised.ResultsAfter a follow-up period of at least 12 months after one or two DLES sessions, healing was observed in 95.24% of the cases. Only 4 cases showed relapse.ConclusionsThe DLES technique is a new therapeutic option for the treatment of orofacial LFVM, is minimally-invasive, allows an outpatient setting and achieves excellent functional and esthetic results avoiding more aggressive procedures
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