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Search Results: 1 - 10 of 151848 matches for " Gabriel F.; "
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Noncommutative Phase Space and the Two Dimensional Quantum Dipole in Background Electric and Magnetic Fields  [PDF]
Anselme F. Dossa, Gabriel Y. H. Avossevou
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.410168
Abstract:

The two dimensional quantum dipole springs in background uniform electric and magnetic fields are first studied in the conventional commutative coordinate space, leading to rigorous results. Then, the model is studied in the framework of the noncommutative (NC) phase space. The NC Hamiltonian and angular momentum do not commute any more in this space. By the means of the su(1,1) symmetry and the similarity transformation, exact solutions are obtained for both the NC angular momentum and the NC Hamiltonian.

Hipertensión pulmonar: severa enfermedad que día a día conocemos más Pulmonary hypertension: a severe disease that each day becomes better known
Gabriel F Díaz
Revista Colombiana de Cardiología , 2012,
Abstract:
Hipertensión pulmonar a moderada altura en ni os Pulmonary hypertension at moderate altitude in children
Gabriel F Díaz
Revista Colombiana de Cardiología , 2012,
Abstract: Se reporta la carencia de estudios sobre la relación entre hipertensión pulmonar y altura en ni os y, con base en la fisiología de esta última, se hace énfasis en la importancia de la hipoxia hipobárica, que desempe a un papel determinante en la etio y biopatogénesis de la hipertensión pulmonar del habitante de la altura. En cuanto a la biopatogénesis, se se ala la importancia de la hiperreactividad del lecho vascular pulmonar y su correcta evaluación. De igual forma, se resumen las patologías relacionadas con hipertensión pulmonar en el ni o habitante de la altura y, finalmente, en lo que respecta al tratamiento de la hipertensión pulmonar del habitante de la altura, se resalta, a través de la evolución de casos clínicos, la importancia de vivir a baja altura sobre el nivel del mar. We report the lack of studies on the relationship between pulmonary hypertension and altitude above sea level in children, and based on the physiology of the latter we emphasize the importance of hypobaric hypoxia, which plays a determinant role in the etiology and bio-pathogenesis of pulmonary hypertension of the altitude inhabitants. Regarding the bio-pathogenesis, we indicate the importance of the hyper-reactivity of the pulmonary vascular bed and its correct evaluation. Similarly, we make a summary of pathologies related to pulmonary hypertension in the child living in the altitude, and finally, with respect to the treatment of pulmonary hypertension of the altitude inhabitants, we highlight through the evolution of clinical cases the importance of living at low altitude above sea level.
Juntas en edificios de acero Joints in steel buildings
Valencia Clement Gabriel F.
Ingeniería e Investigación , 2006,
Abstract: Los elementos de mampostería y los miembros de acero usados en la construcción de edificios se mantienen en constante movimiento. Los cambios volumétricos son producto de las variaciones de temperatura y las deformaciones producidas por las cargas estáticas o dinámicas, y en algunos materiales, por los cambios en el contenido de humedad dentro de los mismos, tal el caso de la mampostería. El presente articulo está dirigido a la determinación de cuándo se requieren juntas de expansión o sísmicas, y como proporcionarlas y dise arlas con propiedad, específicamente en edificios de acero. No se incluye el estudio de las juntas en estructuras de concreto, en muros, ni otros elementos arquitectónicos. Masonry and steel components used in constructing buildings are in a constant state of motion. Volumetric changes are produced by temperature variation and deformation resulting from static or dynamic loading and in some materials, such as masonry, due to moisture content. This article addresses means of determining when expansion and seismic joints are required and how to proportion and design appropriate joints, specifically in steel buildings. It does not cover the study of expansion joints in concrete structures, in masonry construction or in non-structural (architectural) elements.
A new approach to the Child-Langmuir law
Gabriel Gonzalez,F. J. Gonzalez
Physics , 2015,
Abstract: We analyze the motion of charged particles in a vacuum tube diode using a new set of variables. We obtain the space charge limited current for a charged particle moving non-relativistically in one dimension for the case of zero and non zero initial velocity. Our approach gives a new physical insight into the Child-Langmuir law and avoids the need of solving a nonlinear differential equation.
Cynanchum pachyphyllum (Apocynaceae, Asclepiadoideae), una nueva cita para la Flora Argentina
Rua,Gabriel H.; Vidoz,Félix F.;
Bolet?-n de la Sociedad Argentina de Bot??nica , 2005,
Abstract: cynanchum pachyphyllum was collected near lago puelo (chubut, argentina). this species, known from southern chile, is reported for the first time for argentina. a description and an illustration is provided, as well as a key to the related patagonian species.
Cynanchum pachyphyllum (Apocynaceae, Asclepiadoideae), una nueva cita para la Flora Argentina Cynanchum pachyphyllum (Apocynaceae, Asclepiadoideae), a new cite for the Argentine flora
Gabriel H. Rua,Félix F. Vidoz
Boletín de la Sociedad Argentina de Botánica , 2005,
Abstract: Cynanchum pachyphyllum fue colectado en las inmediaciones del Lago Puelo (Chubut, Argentina). Esta especie, conocida hasta el presente sólo para el sur de Chile, es citada por primera vez para la Argentina. Se adjunta una descripción y una ilustración, además de una clave para identificar las especies patagónicas afines. Cynanchum pachyphyllum was collected near Lago Puelo (Chubut, Argentina). This species, known from Southern Chile, is reported for the first time for Argentina. A description and an illustration is provided, as well as a key to the related Patagonian species.
Calificación de una conexión rígida de una viga I y una columna tubular rellena de concreto bajo la acción de cargas dinámicas
Uribe Vallejo,Maritza; Valencia Clement,Gabriel F.;
Ingeniería e Investigación , 2009,
Abstract: using prequalified connections during the structural design stage becomes increasingly necessary when developing structural engineering projects which include steel elements; this is so that the steel elements? appropriate behavior can be ensured according to the structural system and seismic demand. unfortunately, the international entities providing this type of information (i.e. fema) only have a limit series of prequalified connections and such series do not include rigid connections between steel beams and concrete filled tubular (cft) columns having an extended end plate, which has become a very widespread building practice in colombia. this paper describes the most important aspects of a study at the universidad nacional de colombia concerning the behavior of a steel beam rigidly connected to a cft-column, using six physical models having different width-thickness ratio (b/t) columns. ansys v.10 software was used for studying theoretical models (finite elements analysis) for comparative analysis of cyclic test theoretical and experimental results for each specimen presented for the qualification phase. the six tested specimens? hysteretic curves are presented. several conclusions are drawn concerning finite element validation for this type of connection and the influence of width-thickness ratio (b/t) variation and design recommendations for suitable behavior under dynamic loads when this type of connection was used.
EL ESCáNER CONVENCIONAL, UNA HERRAMIENTA úTIL PARA LA CATALOGACIóN DE ORGANISMOS MARINOS
Reyes F.,Javier; Navas S.,Gabriel R.;
Boletín de Investigaciones Marinas y Costeras - INVEMAR , 2000,
Abstract: a cheap and versatile methodology to get digital images of dry and wet preserved organisms, using a flat bed scanner, is presented. to obtain the images of wet specimens, a shallow pool was glued on top of the scanner glass. the pool is filled with water or alcohol and the organisms are immersed and their structures expanded. the best images were obtained with organisms between 1.5 and 15 cm in lenght.the depth of field was limited to 1.2 cm. these images are also useful for taxonomical research without the need of manipulating the organisms; they can be used too, to compare with better accuracy certain structures between different specimens.
ESTIMATIVA DAS PROPRIEDADES DE CAROTENóIDES POR MéTODOS DE CONTRIBUI??O DE GRUPOS
SILVA, Gabriel F. da;CABRAL, Fernando A.;
Ciência e Tecnologia de Alimentos , 1997, DOI: 10.1590/S0101-20611997000400022
Abstract: some groups contribution method were selected and employed in the estimation of bixin and norbixin properties, which are present in pigments of annatto, and other compounds with like structure as carotenoids. just inexistence of experimental data, except for fusion temperature, the estimated values by methods different were compared among itself. the result analysis showing considerable error boiling normal temperature, critical temperature and critical pressure and small error for density e critical volume, however, can appraise the methods are more adequate for different properties of compounds studied.
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