2,350 research outputs found

    Inhomogeneous cortical synchronization and partial epileptic seizures

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    Objective: Interictal synchronization clusters have recently been described in several publications using diverse techniques, including neurophysiological recordings and fMRI, in patients suffering from epilepsy. However, little is known about the role of these hypersynchronous areas during seizures. In this work, we report an analysis of synchronization clusters jointly with several network measures during seizure activity; we then discuss our findings in the context of prior literature.Methods: Subdural activity was recorded by electrocorticography (with 60 electrodesplaced at temporal and parietal lobe locations) in a patient with temporal lobe epilepsywith partial seizures with and without secondary generalization (SG). Both interictal andictal activities (during four seizures) were investigated and characterized using local synchronization and complex network methodology. The modularity, density of links, average clustering coefficient, and average path lengthswere calculated to obtain information about the dynamics of the global network. Functional connectivity changes during the seizures were compared with the time evolution of highly synchronized areas.Results: Our findings reveal temporal changes in local synchronization areas during seizuresand a tight relationship between the cortical locations of these areas and the patterns oftheir evolution over time. Seizure evolution and SG appear to be driven by two differentunderlying mechanisms.Fil: Vega Zelaya, Lorena. Hospital Universitario la Princesa; EspañaFil: Pastor, Jesús Eduardo. Hospital Universitario la Princesa; EspañaFil: García de Sola, Rafael. Hospital Universitario la Princesa; EspañaFil: Ortega, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; Argentin

    Bybliometric analysis of Argentinean scientific publications in the Agriculture, Multidisciplinary subject category in Web of Science database (1997-2009)

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    El propósito del trabajo ha sido caracterizar el área de Agriculture, Multidisciplinary en Argentina, revisándose a nivel institucional, a través de la base de datos Web of Science, los trabajos realizados por investigadores en Instituciones argentinas y publicados en revistas internacionales con factor de impacto entre 1997 y 2009. En el contexto de América Latina, se han publicado 7795 trabajos de todos los tipos documentales y 7622 del tipo artículo o revisión en 49 revistas, y a nivel de Argentina se han encontrado 531 artículos o revisiones publicados en 31 revistas, la mayoría en inglés (80,23%), pero también en español (15,25%) y en portugués (4,33%). Por otro lado, se han analizado las Instituciones desde el punto de vista cuantitativo y cualitativo mediante diversos indicadores bibliométricos, como el Factor de Impacto Ponderado, el Factor de Impacto Relativo y la ratio número de citas frente a número de documentos, encontrándose que entre las instituciones más productivas destacan el Consejo Nacional de Investigaciones Científicas y Técnicas por el número de documentos y el Centro de Investigación y Desarrollo en Criotecnología de Alimentos por el Factor de Impacto Ponderado y por la ratio citas frente a documentos. Se observa una escasa colaboración internacional.The purpose of this study was to characterize the subject area of Agriculture, Multidisciplinary in Argentina, reviewing at institutional level, the work done by researchers at institutions in Argentina and published in international journals with impact factor among 1997 and 2009, through the Web of Science database. In the context of Latin America, 7795 have been published works of all types and 7622 article or review in 49 journals, and at the level of Argentina have been found 531 articles or reviews published in 31 journals, mostly in English (80.23 %), but also in Spanish (15.25%) and Portuguese (4.33%). Moreover, the institutions have been analyzed from the point of view quantitative and qualitative through various bibliometric indicators, such as Weighted and Relative Impact Factor and the ratio number of citations compared to the number of documents, finding that among the most productive institutions include the National Council for Scientific and Technical Research by the number of documents, and the Center for Research and Development in Food Cryotechnology by the Weighted Impact Factor and the ratio citations against documents, showing a little international collaboration.Fil: Rojas-Sola, José Ignacio. España. Universidad de Jaén. Escuela Politécnica Superior de Jaén.Fil: De San Antonio-Gómez, Carlos. Universidad Politécnica de Madri

    Agustín de Betancourt’s Optical Telegraph: Geometric Modeling and Virtual Reconstruction

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    This article shows the geometric modeling and virtual reconstruction of the optical telegraph by Agustín de Betancourt and Abraham Louis Breguet developed at the end of the 18th century. Autodesk Inventor Professional software has been used to obtain the three-dimensional (3D) model of this historical invention and its geometric documentation. The material for the research is available on the website of the Betancourt Project of the Canary Orotava Foundation for the History of Science. Thanks to the three-dimensional modeling performed, it has been possible to explain in detail both its operation and the assembly system of this invention in a coherent way. After carrying out its 3D modeling and functional analysis, it was discovered that the transmissions in the telegraph were not performed by hemp ropes but rather by metal chains with flat links, considerably reducing possible error. Similarly, it has also been found that the use of the gimbal joint facilitated the adaptability of the invention to geographical areas where there was a physical impediment to the alignment of telegraph stations. In addition, it was not now necessary for the telescope frames to be located parallel to the mast frame (frame of the indicator arrow) and therefore they could work in different planes.This research was supported by the Spanish Ministry of Economic Affairs and Competitiveness under the Spanish Plan of Scientific and Technical Research and Innovation (2013–2016), and the European Fund for Regional Development (EFRD) under grant number [HAR2015-63503-P]

    The Hay Inclined Plane in Coalbrookdale (Shropshire, England): Analysis through Computer-Aided Engineering

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    This article analyzes the ‘Hay inclined plane’ designed by the English engineer and entrepreneur William Reynolds and put into operation in 1792 to facilitate the transport of vessels between channels at different levels using an inclined plane. To this end, a study of computer-aided engineering (CAE) was carried out using the parametric software Autodesk Inventor Professional, consisting of a static analysis using the finite-element method (FEM) of the 3D model of the invention under real operating conditions. The results obtained after subjecting the mechanism to the two most unfavorable situations (blockage situation of the inertia flywheel and emergency braking situation) indicate that, with the exception of the braking bar, the rest of the assembly is perfectly designed and dimensioned. In particular, for the blockage situation, the point with the greatest stress is at the junction between the inertia flywheel and the axle to which it is attached, the maximum value of von Mises stress being at that point (186.9 MPa) lower than the elastic limit of the cast iron. Also, at this point the deformation is very low (0.13% of its length), as well as the maximum displacement that takes place in the inertia flywheel itself (22.98 mm), and the lowest safety factor has a value of 3.51 (located on the wooden shaft support), which indicates that the mechanism is clearly oversized. On the other hand, the emergency braking situation, which is technically impossible with a manual operation, indicates that the braking bar supports a maximum von Mises stress of 1025 MPa, above the elastic limit of the material, so it would break. However, other than that element, the rest of the elements have lower stresses, with a maximum value of 390.7 MPa, and with safety factors higher than 1.7, which indicates that the mechanism was well dimensioned.This research was funded by the Spanish Ministry of Economic Affairs and Competitiveness (MINECO), under the Spanish Plan of Scientific and Technical Research and Innovation (2013–2016) and European Fund Regional Development (EFRD) under grant number [HAR2015-63503-P]

    Agustin de Betancourt’s Wind Machine for Draining Marshy Ground: Approach to Its Geometric Modeling with Autodesk Inventor Professional

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    The present study shows the process followed in making the three-dimensional model and geometric documentation of a historical invention of the renowned Spanish engineer Agustin de Betancourt y Molina, which forms part of his rich legacy. Specifically, this was a wind machine for draining marshy ground, designed in 1789. The present research relies on the computer-aided design (CAD) techniques using Autodesk Inventor Professional software, based on the scant information provided by the only two drawings of the machine, making it necessary to propose a number of dimensional and geometric hypotheses as well as a series of movement restrictions (degrees of freedom), to arrive at a consistent design. The results offer a functional design for this historic invention

    The Conical Stones Olive Oil Mill: Analysis through Computer-Aided Engineering

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    This article analyzes an olive oil mill formed of four conical stones used in the milling of the olive. To this end, a study of computer-aided engineering (CAE) was carried out using the parametric software Autodesk Inventor Professional, consisting of a static analysis using the finite-element method (FEM) of the three-dimensional (3D) model of the mill under real operating conditions. The results obtained revealed that the conical stones mill was a very robust machine. When studying the assembly in the most unfavorable situation (blockage of one of its millstones), we observed that the element with the highest von Mises stress was the bearing nut, reaching a value of 263.9 MPa, which was far from the elastic limit of cast iron (758 MPa). On the other hand, the machine hardly presented any equivalent deformations or displacements that could jeopardize the operation as a whole. The maximum displacement obtained was 2.494 mm in the inertia flywheel, and the equivalent deformations did not reach 0.1% of the part dimension. Similarly, the element with the lowest safety coefficient (2.87) was the same bearing nut with the highest von Mises stress, although the next element with the second lowest safety coefficient had a value of 8.69, which showed that the set was clearly oversized. These results demonstrate the convenience of redesigning the set in order to resize some of its elements, and that they could have lower safety coefficients of between 2 and 4. After an initial analysis, the resizable elements would fundamentally be those related to the movement transmission system and the frame structure

    Geometric Modeling of the Machine for Cutting Cane and Other Aquatic Plants in Navigable Waterways by Agustín de Betancourt y Molina

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    This article presents the steps followed to obtain a three-dimensional model of one of the most recognized historical inventions of Agustín de Betancourt y Molina from the scant documentation found about it. Specifically, this was a machine for cutting cane and other aquatic plants in navigable waterways, presented in London in 1795. The study is based on computer-aided design (CAD) techniques using Autodesk Inventor Professional, from the information provided by the only two sheets that exist from the machine, one with specifications in English and the other in French, both very similar. In order to obtain a functional result on which to carry out further studies, it has been necessary to make some geometrical hypotheses on the models, aimed to find the correct dimension of each element. In addition, it has also been necessary to define the relationship of each element with those that set up its environment, defining movement restrictions, so that the final model, behaves as real as possible.This research has been developed within the research project entitled “Agustín de Betancourt’s historical heritage: a comprehensive study of contributions to the civil engineering from the perspective of engineering graphics for its valuation and dissemination” (HAR2015-63503-P), funded by the Spanish Ministry of Economic Affairs and Competitiveness, under the Spanish Plan of Scientific and Technical Research and Innovation (2013–2016), and European Fund Regional Development (EFRD

    Análisis bibliométrico de las publicaciones científicas mexicanas en la categoría de Engineering, Chemical en la base de datos del Web of Science (1997-2008)

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    El proposito del trabajo ha sido caracterizar el área de Ingeniería Química en México. Para ello, se ha revisado a nivel institucional, a través de la base de datos Web of Science (WoS), los trabajos sobre Ingeniería Química realizados por investigadores en Instituciones mexicanas y publicados en revistas internacionales con factor de impacto entre 1997 y 2008. Se ha partido del contexto de América Latina, donde se han publicado 6,183 trabajos del tipo artículo o revisión en 119 revistas, y a nivel de México se han encontrado 1,302 artículos publicados en 87 revistas la mayoría en inglés (96.08%), pero también en español (3.69%) y en francés (0.23%). Por otro lado, se han analizado las Universidades y Centros de Investigación desde el punto de vista cuantitativo y cualitativo mediante diversos indicadores bibliométricos como el Factor de Impacto Ponderado, el Factor de Impacto Relativo y la relación entre el número de citas y el número de documentos, encontrándose que de entre las cinco instituciones más productivas destaca el Instituto Mexicano del Petróleo por el número de documentos y la Universidad Nacional Autónoma de México por la relación citas frente a documentos, y por el Factor de Impacto Ponderado

    El uso problemático del teléfono móvil: desde el abuso a su consideración como adicción comportamental

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    El objetivo general de esta investigación se ha dirigido al análisis del uso problemático del teléfono móvil entre la población española, desde los 16 a los 65 años de edad. Nuestra hipótesis se ha basado en la consideración de que dicho uso problemático respondería a los criterios de adicción, como lo son las sustancias y el juego patológico, y que por lo tanto, como otras adicciones, es capaz de afectar a capas amplias de la población, no solo a jóvenes y adolescentes. En la consecución de dicho objetivo se llevó a cabo inicialmente un estudio y revisión del histórico de investigaciones precedentes, tanto en el ámbito de la impulsividad como en la propia consideración del teléfono móvil como adicción comportamental. Posteriormente se realizó un trabajo de campo con una muestra de ámbito nacional, en 17 comunidades autónomas de España, con un total de 1.126 entrevistas y un cuestionario semiestructurado aplicado mediante un procedimiento on-line. Como resultado de este trabajo se presentan cinco artículos, tanto publicados como en actual revisión por las revistas correspondientes. En el primer artículo se ha pretendido analizar el peso e importancia, en el histórico de investigaciones precedentes, de la impulsividad como antesala de las adicciones en general, así como en el contexto de las nuevas adicciones sociales o comportamentales. Teniendo en cuenta que progresivamente existe un creciente número de publicaciones que analizan la extensión de dicho modelo al ámbito comportamental, se desprende que la impulsividad tiene un papel esencial en este proceso, encontrándose sin embargo también asociada con frecuencia a otras patologías. En este trabajo se concluye por lo tanto que el modelo de adicción a sustancias puede ser aplicable al campo de las adicciones comportamentales considerando la impulsividad como precedente..

    Análisis bibliométrico de las publicaciones científicas mexicanas en la categoría de Engineering, Chemical en la base de datos del Web of Science (1997-2008)

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    El proposito del trabajo ha sido caracterizar el área de Ingeniería Química en México. Para ello, se ha revisado a nivel institucional, a través de la base de datos Web of Science (WoS), los trabajos sobre Ingeniería Química realizados por investigadores en Instituciones mexicanas y publicados en revistas internacionales con factor de impacto entre 1997 y 2008. Se ha partido del contexto de América Latina, donde se han publicado 6,183 trabajos del tipo artículo o revisión en 119 revistas, y a nivel de México se han encontrado 1,302 artículos publicados en 87 revistas la mayoría en inglés (96.08%), pero también en español (3.69%) y en francés (0.23%). Por otro lado, se han analizado las Universidades y Centros de Investigación desde el punto de vista cuantitativo y cualitativo mediante diversos indicadores bibliométricos como el Factor de Impacto Ponderado, el Factor de Impacto Relativo y la relación entre el número de citas y el número de documentos, encontrándose que de entre las cinco instituciones más productivas destaca el Instituto Mexicano del Petróleo por el número de documentos y la Universidad Nacional Autónoma de México por la relación citas frente a documentos, y por el Factor de Impacto Ponderado
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