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Search Results: 1 - 10 of 224653 matches for " Villanueva R "
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Rese a de "Antología de Comunicación para el Cambio Social: Lecturas históricas y contemporáneas" de Alfonso Gumucio-Dagron y Thomas Tufte (compiladores)
Erick R. Torrico Villanueva
Estudios sobre las Culturas Contemporaneas , 2010,
Abstract:
Acercamiento a la comunicación como cultura académica y a sus proposiciones teóricas generales
Erick R. Torrico Villanueva
Conex?o : Comunica??o e Cultura , 2005,
Abstract: Aunque la discusión sobre el estatuto científico de la Comunicación todavía plantea diversas interrogantes y profundos antagonismos, lo que sí es posible sostener más allá de las discrepancias sobre la materia es que existe una cultura académica cuyo objeto de referencia común son los procesos sociales de producción, circulación, intercambio y usos de significaciones y sentidos culturalmente situados y mediados o no por tecnologías. Dicha cultura consiste en un conjunto más o menos sistemático de proposiciones desarrolladas por autores fundamentales en los variados y aun contradictorios momentos de institución del campo, las cuales han sido asumidas por gran parte de la comunidad especializada y condicionan sus prácticas de investigación, formación y profesionales sin ser sometidas a debate por lo general. El artículo ofrece un acercamiento preliminar a esa cultura y a sus proposiciones generales.
Generalized Green's functions for higher order boundary value matrix differential systems
R. J. Villanueva,L. Jodar
International Journal of Mathematics and Mathematical Sciences , 1992, DOI: 10.1155/s0161171292000681
Abstract: In this paper, a Green's matrix function for higher order two point boundary value differential matrix problems is constructed. By using the concept of rectangular co-solution of certain algebraic matrix equation associated to the problem, an existence condition as well as an explicit closed form expression for the solution of possibly not well-posed boundary value problems is given avoiding the increase of the problem dimension.
On the Null Trajectories in Conformal Weyl Gravity
J. R. Villanueva,Marco Olivares
Physics , 2013, DOI: 10.1088/1475-7516/2013/06/040
Abstract: In this work we find analytical solutions to the null geodesics around a black hole in the conformal Weyl gravity. Exact expressions for the horizons are found, and they depend on the cosmological constant and the coupling constants of the conformal Weyl gravity. Then, we study the radial motion from the point of view of the proper and coordinate frames, and compare it with that found in spacetimes of general relativity. The angular motion is also examined qualitatively by means of an effective potential; quantitatively, the equation of motion is solved in terms of $\wp$-Weierstrass elliptic function. Thus, we find the deflection angle for photons without using any approximation, which is a novel result for this kind of gravity.
Gravitational Rutherford scattering and Keplerian orbits for electrically charged bodies in heterotic string theory
J. R. Villanueva,Marco Olivares
Physics , 2015,
Abstract: Properties of the motion of electrically charged particles in the background of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS) black hole is presented in this paper. Radial and angular motion are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analysed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys. Rev. D 85: 024033, 2012), Olivares & Villanueva (Eur. Phys. J. C 73: 2659, 2013) and Blaga (Automat. Comp. Appl. Math. 22, 41 (2013); Serb. Astron. J. 190, 41 (2015)) for time-like geodesics.
Fisiopatología y técnicas de registro de los movimientos oculares
Gila,L.; Villanueva,A.; Cabeza,R.;
Anales del Sistema Sanitario de Navarra , 2009, DOI: 10.4321/S1137-66272009000600002
Abstract: a number of functional systems are involved in the control of eye movements. the vestibulo-ocular and optokinetic reflexes are automatic responses that compensate for the movements of the head and those of the visual environment in order to stabilize the retinal image on a given fixation point. the saccadic movements are quick displacements of fixation from one to another point in the visual field. the smooth pursuit movements consist in the gaze following a moving target. finally, there are some involuntary movements of very small amplitude during fixation maintenance. each functional modality of movement depends on specific neuronal circuits that work in a coordinated manner for encoding the contraction of the oculomotor muscles to reach an adequate position at every moment. these neuronal systems can be altered by many neurological processes of different kinds and localizations, causing a broad variety of oculomotor disturbances. the most salient aspects of the physiopathology and the recording systems of eye movements are reviewed.
Fisiopatología y técnicas de registro de los movimientos oculares Physiopathology and recording techniques of ocular movements
L. Gila,A. Villanueva,R. Cabeza
Anales del Sistema Sanitario de Navarra , 2009,
Abstract: En el control de la motilidad ocular intervienen varios sistemas funcionales. Los reflejos vestíbulo-oculares y optocinéticos son respuestas automáticas para compensar los movimientos de la cabeza y del entorno visual y poder estabilizar la imagen retiniana sobre un determinado punto de fijación. Los movimientos sacádicos son rápidos desplazamientos de la fijación de un punto a otro del campo visual. Los movimientos de persecución lenta consisten en el seguimiento de estímulos móviles con la mirada. Finalmente, existen movimientos involuntarios de muy escasa amplitud que se producen durante el mantenimiento de la fijación. Cada modalidad funcional de movimiento depende de circuitos neuronales específicos que trabajan coordinadamente para codificar la contracción de los músculos oculomotores correspondiente a la posición adecuada en cada momento. Estos sistemas neuronales pueden verse alterados por múltiples procesos neurológicos de diferente naturaleza y localización dando lugar a una variada gama de trastornos oculomotores. Se revisan los aspectos más destacados de la fisiopatología y de los sistemas de registro de los movimientos oculares. A number of functional systems are involved in the control of eye movements. The vestibulo-ocular and optokinetic reflexes are automatic responses that compensate for the movements of the head and those of the visual environment in order to stabilize the retinal image on a given fixation point. The saccadic movements are quick displacements of fixation from one to another point in the visual field. The smooth pursuit movements consist in the gaze following a moving target. Finally, there are some involuntary movements of very small amplitude during fixation maintenance. Each functional modality of movement depends on specific neuronal circuits that work in a coordinated manner for encoding the contraction of the oculomotor muscles to reach an adequate position at every moment. These neuronal systems can be altered by many neurological processes of different kinds and localizations, causing a broad variety of oculomotor disturbances. The most salient aspects of the physiopathology and the recording systems of eye movements are reviewed.
Geodesic Structure of Lifshitz Black Holes in 2+1 Dimensions
Norman Cruz,Marco Olivares,J. R. Villanueva
Physics , 2013, DOI: 10.1140/epjc/s10052-013-2485-8
Abstract: We present a study of the geodesic equations of a black hole space-time which is a solution of the three-dimensional NMG theory and is asymptotically Lifshitz with $z=3$ and $d=1$ as found in [Ayon-Beato E., Garbarz A., Giribet G. and Hassaine M., Phys. Rev. {\bf D} 80, 104029 (2009)]. By means of the corresponding effective potentials for massive particles and photons we find the allowed motions by the energy levels. Exact solutions for radial and non-radial geodesics are given in terms of the Weierstrass elliptic $\wp$, $\sigma$, and $\zeta$ functions.
The Kepler problem in the Snyder space
Carlos Leiva,Joel Saavedra,J. R. Villanueva
Physics , 2012,
Abstract: In this paper we study the Kepler problem in the non commutative Snyder scenario. We characterize the deformations in the Poisson bracket algebra under a mimic procedure from quantum standard formulations and taking into account a general recipe to build the noncommutative phase space coordinates (in the sense of Poisson brackets). We obtain an expression to the deformed potential, and then the consequences in the precession of the orbit of Mercury are calculated. This result allows us to find an estimated value for the non commutative deformation parameter introduced.
The geodesic structure of the Schwarzschild Anti-de Sitter black hole
Norman Cruz,Marco Olivares,Jose R. Villanueva
Physics , 2004, DOI: 10.1088/0264-9381/22/6/016
Abstract: In the present work we found the geodesic structure of an AdS black hole. By means of a detailed analyze of the corresponding effective potentials for particles and photon, we found all the possible motions which are allowed by the energy levels. Radial and non radial trajectories were exactly evaluated for both geodesics. The founded orbits were plotted in order to have a direct visualization of the allowed motions. We show that the geodesic structure of this black hole presents new type of motions not allowed by the Schwarzschild spacetime.
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