28 research outputs found

    Optimal measurement setup for damage detection in piezoelectric plates

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    [EN] An optimization of the excitation-measurement configuration is proposed for the characterization of damage in PZT-4 piezoelectric plates, from a numerical point of view. To perform such an optimization, a numerical method to determine the location and extent of defects in piezoelectric plates is developed by combining the solution of an identification inverse problem, using genetic algorithms and gradient-based methods to minimize a cost functional, and using an optimized finite element code and meshing algorithm. In addition, a semianalytical estimate of the probability of detection is developed and validated, which provides a flexible criterion to optimize the experimental design. The experimental setup is optimized upon several criteria: maximizing the probability of detection against noise effects, ensuring robust search algorithm convergence and increasing the sensitivity to the presence of the defect. The measurement of voltage phi is concluded to provide the highest identifiability, combined with an excitation of the specimen by a mechanical traction transverse to the polarization direction. Sufficient accuracy is predicted for the damage location and sizing under realistic noise levels. (c) 2008 Elsevier Ltd. All rights reserved.This research was supported by the Ministry of Education of Spain through Grant No. FPU AP-2006-02372.Rus, G.; Palma Guerrero, R.; Pérez-Aparicio, JL. (2009). Optimal measurement setup for damage detection in piezoelectric plates. International Journal of Engineering Science. 47(4):554-572. https://doi.org/10.1016/j.ijengsci.2008.09.006S55457247

    Usefulness of optic nerve ultrasound to predict clinical progression in multiple sclerosis

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    Introducción La pérdida neuronal/axonal progresiva se considera la causa más importante de discapacidad neurológica en la esclerosis múltiple (EM). El sistema visual está frecuentemente afectado en esta enfermedad y su accesibilidad a test funcionales y estructurales ha permitido que se convierta en un modelo para estudiar in vivo la patogenia de la EM. La ecografía orbitaria permite evaluar, de forma no invasiva y en tiempo real, las diversas estructuras de la órbita, incluido el nervio óptico. Material y métodos Se ha llevado a cabo un estudio observacional ambispectivo en pacientes con EM recogiéndose datos evolutivos de la enfermedad. La ecografía orbitaria se realizó en todos los pacientes según el principio de mínima potencia necesaria (ALARA). También se recogieron los datos de tomografía de coherencia óptica (OCT) en aquellos que tenían realizadas ambas pruebas. El estudio estadístico se efectuó con el programa SPSS 22.0. Resultados Se encontraron correlaciones estadísticamente significativas entre las medidas ecográficas y la progresión de la enfermedad (p = 0,041 para el ojo derecho y p = 0,037 para el ojo izquierdo), y la Expanded Disability Status Scale (EDSS) final en el seguimiento (p = 0,07 para el ojo derecho y p = 0,043 para el ojo izquierdo). No fue así para los datos referentes a brotes y a otras variables clínicas. Discusión La medición del diámetro del nervio óptico por ecografía podría utilizarse como medida predictiva en la evolución de la EM, ya que la disminución del mismo se asocia con progresión clínica y mayor discapacidad, medidas con la EDSS.Introduction Progressive neuronal and axonal loss are considered the main causes of disability in patients with multiple sclerosis (MS). The disease frequently involves the visual system; the accessibility of the system for several functional and structural tests has made it a model for the in vivo study of MS pathogenesis. Orbital ultrasound is a non-invasive technique that enables various structures of the orbit, including the optic nerve, to be evaluated in real time. Material and methods We conducted an observational, ambispective study of MS patients. Disease progression data were collected. Orbital ultrasound was performed on all patients, with power set according to the ‘as low as reasonably achievable’ (ALARA) principle. Optical coherence tomography (OCT) data were also collected for those patients who underwent the procedure. Statistical analysis was conducted using SPSS version 22.0. Results Disease progression was significantly correlated with ultrasound findings (P = .041 for the right eye and P = .037 for the left eye) and with Expanded Disability Status Scale (EDSS) score at the end of the follow-up period (P = .07 for the right eye and P = .043 for the left eye). No statistically significant differences were found with relation to relapses or other clinical variables. Discussion Ultrasound measurement of optic nerve diameter constitutes a useful, predictive factor for the evaluation of patients with MS. Smaller diameters are associated with poor clinical progression and greater disability (measured by EDSS)

    Multiphysics and Thermodynamic Formulations for Equilibrium and Non-equilibrium Interactions: Non-linear Finite Elements Applied to Multi-coupled Active Materials

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    [EN] Combining several theories this paper presents a general multiphysics framework applied to the study of coupled and active materials, considering mechanical, electric, magnetic and thermal fields. The framework is based on thermodynamic equilibrium and non-equilibrium interactions, both linked by a two-temperature model. The multi-coupled governing equations are obtained from energy, momentum and entropy balances; the total energy is the sum of thermal, mechanical and electromagnetic parts. The momentum balance considers mechanical plus electromagnetic balances; for the latter the Abraham rep- resentation using the Maxwell stress tensor is formulated. This tensor is manipulated to automatically fulfill the angular momentum balance. The entropy balance is for- mulated using the classical Gibbs equation for equilibrium interactions and non-equilibrium thermodynamics. For the non-linear finite element formulations, this equation requires the transformation of thermoelectric coupling and conductivities into tensorial form. The two-way thermoe- lastic Biot term introduces damping: thermomechanical, pyromagnetic and pyroelectric converse electromagnetic dynamic interactions. Ponderomotrix and electromagnetic forces are also considered. The governing equations are converted into a variational formulation with the resulting four-field, multi-coupled formalism implemented and val- idated with two custom-made finite elements in the research code FEAP. Standard first-order isoparametric eight-node elements with seven degrees of freedom (dof) per node (three displacements, voltage and magnetic scalar potentials plus two temperatures) are used. Non-linearities and dynamics are solved with Newton-Raphson and New- mark-b algorithms, respectively. Results of thermoelectric, thermoelastic, thermomagnetic, piezoelectric, piezomag- netic, pyroelectric, pyromagnetic and galvanomagnetic interactions are presented, including non-linear depen- dency on temperature and some second-order interactions.This research was partially supported by grants CSD2008-00037 Canfranc Underground Physics, Polytechnic University of Valencia under programs PAID 02-11-1828 and 05-10-2674. The first author used the grant Generalitat Valenciana BEST/2014/232 for the completion of this work.Pérez-Aparicio, JL.; Palma, R.; Taylor, R. (2016). Multiphysics and Thermodynamic Formulations for Equilibrium and Non-equilibrium Interactions: Non-linear Finite Elements Applied to Multi-coupled Active Materials. Archives of Computational Methods in Engineering. 23:535-583. https://doi.org/10.1007/s11831-015-9149-9S53558323Abraham M (1910) Sull’elettrodinamica di Minkowski. 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    The management of acute venous thromboembolism in clinical practice. Results from the European PREFER in VTE Registry

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    Venous thromboembolism (VTE) is a significant cause of morbidity and mortality in Europe. Data from real-world registries are necessary, as clinical trials do not represent the full spectrum of VTE patients seen in clinical practice. We aimed to document the epidemiology, management and outcomes of VTE using data from a large, observational database. PREFER in VTE was an international, non-interventional disease registry conducted between January 2013 and July 2015 in primary and secondary care across seven European countries. Consecutive patients with acute VTE were documented and followed up over 12 months. PREFER in VTE included 3,455 patients with a mean age of 60.8 ± 17.0 years. Overall, 53.0 % were male. The majority of patients were assessed in the hospital setting as inpatients or outpatients (78.5 %). The diagnosis was deep-vein thrombosis (DVT) in 59.5 % and pulmonary embolism (PE) in 40.5 %. The most common comorbidities were the various types of cardiovascular disease (excluding hypertension; 45.5 %), hypertension (42.3 %) and dyslipidaemia (21.1 %). Following the index VTE, a large proportion of patients received initial therapy with heparin (73.2 %), almost half received a vitamin K antagonist (48.7 %) and nearly a quarter received a DOAC (24.5 %). Almost a quarter of all presentations were for recurrent VTE, with >80 % of previous episodes having occurred more than 12 months prior to baseline. In conclusion, PREFER in VTE has provided contemporary insights into VTE patients and their real-world management, including their baseline characteristics, risk factors, disease history, symptoms and signs, initial therapy and outcomes

    Consenso de expertos sobre el uso de alemtuzumab en la práctica clínica diaria en España

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    Introducción: Alemtuzumab es un fármaco de alta eficacia aprobado por la Agencia Europea de Medicamentos como tratamiento modificador de la enfermedad en pacientes con esclerosis múltiple remitente recurrente. Objetivo: Elaborar un documento de consenso sobre el manejo de alemtuzumab en la práctica clínica habitual, que sea de aplicación en el ámbito español. Desarrollo: Un grupo de expertos en esclerosis múltiple revisó las publicaciones disponibles hasta diciembre de 2017, de tratamiento con alemtuzumab y esclerosis múltiple. Se incluyeron trabajos sobre eficacia, efectividad y seguridad, despistaje de infecciones y vacunación, administración y monitorización. La propuesta inicial de recomendaciones fue desarrollada por un grupo coordinador con base en la evidencia disponible y en su experiencia clínica. El proceso de consenso se llevó a cabo en 2 etapas; se estableció como porcentaje inicial de acuerdo grupal el 80%. El documento final con todas las recomendaciones acordadas por el grupo de trabajo se sometió a revisión externa y los comentarios recibidos fueron considerados por el grupo coordinador. Conclusiones: El documento aportado pretende ser una herramienta útil para facilitar el manejo del fármaco en condiciones de práctica clínica habitual.Introduction: Alemtuzumab is a highly effective drug approved by the European Medicines Agency as a disease-modifying drug for the treatment of relapsing-remitting multiple sclerosis. Objective: A consensus document was drafted on the management of alemtuzumab in routine clinical practice in Spain. Development: A group of multiple sclerosis specialists reviewed articles addressing treatment with alemtuzumab in patients with multiple sclerosis and published before December 2017. The included studies assessed the drug's efficacy, effectiveness, and safety; screening for infections and vaccination; and administration and monitoring aspects. The initial proposed recommendations were developed by a coordinating group and based on the available evidence and their clinical experience. The consensus process was carried out in 2 stages, with the initial threshold percentage for group agreement established at 80%. The final document with all the recommendations agreed by the working group was submitted for external review and the comments received were considered by the coordinating group. Conclusion: The present document is intended to be used as a tool for optimising the management of alemtuzumab in routine clinical practice

    Consensus statement on the use of alemtuzumab in daily clinical practice in Spain

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    Introducción: Alemtuzumab es un fármaco de alta eficacia aprobado por la Agencia Europeade Medicamentos como tratamiento modificador de la enfermedad en pacientes con esclerosismúltiple remitente recurrente.Objetivo: Elaborar un documento de consenso sobre el manejo de alemtuzumab en la práctica clínica habitual, que sea de aplicación en el ámbito español.Desarrollo: Un grupo de expertos en esclerosis múltiple revisó las publicaciones disponibles hasta diciembre de 2017, de tratamiento con alemtuzumab y esclerosis múltiple. Se incluyeron trabajos sobre eficacia, efectividad y seguridad, despistaje de infecciones y vacunación, admi-nistración y monitorización. La propuesta inicial de recomendaciones fue desarrollada por un grupo coordinador con base en la evidencia disponible y en su experiencia clínica. El proceso de consenso se llevó a cabo en 2 etapas; se estableció como porcentaje inicial de acuerdo grupal el 80%. El documento final con todas las recomendaciones acordadas por el grupo de trabajo se sometió a revisión externa y los comentarios recibidos fueron considerados por el grupo coordinador. Conclusiones: El documento aportado pretende ser una herramienta útil para facilitar el manejo del fármaco en condiciones de práctica clínica habitualtIntroduction: Alemtuzumab is a highly effective drug approved by the European Medicines Agency as a disease-modifying drug for the treatment of relapsing-remitting multiple sclerosis. Objective: A consensus document was drafted on the management of alemtuzumab in routineclinical practice in Spain. Development: A group of multiple sclerosis specialists reviewed articles addressing treatment with alemtuzumab in patients with multiple sclerosis and published before December 2017. The included studies assessed the drug’s efficacy, effectiveness, and safety; screening for infections and vaccination; and administration and monitoring aspects. The initial proposed recommendations were developed by a coordinating group and based on the available evidence and their clinical experience. The consensus process was carried out in 2 stages, with the initial threshold percentage for group agreement established at 80%. The final document with all the recom-mendations agreed by the working group was submitted for external review and the comments received were considered by the coordinating group. Conclusion: The present document is intended to be used as a tool for optimising the management of alemtuzumab in routine clinical practiceLa elaboración de este manuscrito ha sido financiada por Sanofi-Genzym

    An enigma in the genetic responses of plants to salt stresses

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    Soil salinity is one of the main factors restricting crop production throughout the world. Various salt tolerance traits and the genes controlling these traits are responsible for coping with salinity stress in plants. These coping mechanisms include osmotic tolerance, ion exclusion, and tissue tolerance. Plants exposed to salinity stress sense the stress conditions, convey specific stimuli signals, and initiate responses against stress through the activation of tolerance mechanisms that include multiple genes and pathways. Advances in our understanding of the genetic responses of plants to salinity and their connections with yield improvement are essential for attaining sustainable agriculture. Although a wide range of studies have been conducted that demonstrate genetic variations in response to salinity stress, numerous questions need to be answered to fully understand plant tolerance to salt stress. This chapter provides an overview of previous studies on the genetic control of salinity stress in plants, including signaling, tolerance mechanisms, and the genes, pathways, and epigenetic regulators necessary for plant salinity tolerance
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