937 resultados para gravitational wave detector
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Determinar si el test de Bender puede discriminar, en niños de cuarto y quinto de primaria, problemas emocionales y comportamentales y poder establecer un diagnóstico diferencial. Los objetivos específicos se agrupan en tres bloques: 1.- El Test de Bender y variables sociodemográficos. 2.- El test de Bender como prueba madurativa. 3.- El test de Bender como técnica proyectiva. Con el fin de dar respuestas a los objetivos planteados se formula una serie de hipótesis que orientan el análisis de los resultados. Esta investigación consiste en un estudio descriptivo correlacional. Se realiza mediante la aplicación del test Gestáltico Visomotor de Bender. Se trata de una investigación básicamente descriptiva y correlacional, donde se han seleccionado sujetos de diferentes edades (9-11 años) evaluados en un solo momento temporal. Las variables que se han utilizado, se han clasificado en variables sociodemográificas y psicológicas. La población la componen los alumnos de cuarto y quinto de primaria de la población de Huelva, capital y provincia. La elección de los distintos colegios se ha realizado teniendo en cuenta el nivel socioeconómico y profesional de los padres. La muestra está constituida por 722 sujetos de los cuales el 49,8 por ciento corresponde a varones y el 50,1 por ciento a mujeres, escolarizado en colegios públicos y concertados pertenecientes a Huelva capital y periferia. La selección de los instrumentos de medida se establece el criterio de que sean técnicas fiables, asequibles y fáciles de aplicar : Prueba de maduración visomotora: Test Bender. Prueba de capacidad intelectual: Test de Factor 'G' de R. B. Cattell y A. K. S. Cattell (Escala 2, Forma A). Cuestionario de Personalidad para niños EPQ-J De H. J. Eysenck y S. B. G. Eysenck. Cuestionario de autoevaluación Ansiedad estado-rasgo en niños, de C. D. Spielberg et al. Cuestionario para el profesor tutor. El test de Bender se podría emplear como screening para detectar desajustes madurativos que pueden tener como consecuencias problemas emocionales y posibles conductas antisociales, pero no es válido para detectar patologías diferenciales como la ansiedad, neuroticismo y psicoticismo. Se puede considerar esta prueba como un complemento de las técnicas psicométricas y así proporcionar, no sólo una visión analítica, sino una perspectiva más global de la persona. Sin embargo, en la utilización del test de Bender como test de personalidad se deben tener en cuenta los siguientes planteamientos: a. Aplicarlo de forma individual. b. Conveniencia de tener una pequeña entrevista con el niño. c. Es aconsejable que el evaluador tenga experiencia en el manejo de pruebas proyectivas y amplios conocimientos de psicopatología infantil. d. Así mismo, es muy importante que el evaluador tenga cierto entrenamiento y experiencia con el test de Bender. Es importante seguir investigando los índices que se asocian a conductas disruptivas y asociales, pues parece que es donde se han obtenido más relaciones y quizás en un futuro pueda ser utilizada de manera preventiva.
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The accuracy of a 3D reconstruction using laser scanners is significantly determined by the detection of the laser stripe. Since the energy pattern of such a stripe corresponds to a Gaussian profile, it makes sense to detect the point of maximum light intensity (or peak) by computing the zero-crossing point of the first derivative of such Gaussian profile. However, because noise is present in every physical process, such as electronic image formation, it is not sensitive to perform the derivative of the image of the stripe in almost any situation, unless a previous filtering stage is done. Considering that stripe scanning is an inherently row-parallel process, every row of a given image must be processed independently in order to compute its corresponding peak position in the row. This paper reports on the use of digital filtering techniques in order to cope with the scanning of different surfaces with different optical properties and different noise levels, leading to the proposal of a more accurate numerical peak detector, even at very low signal-to-noise ratios
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The aim of this study was to compare the contrast visual processing of concentric sinusoidal gratings stimuli between adolescents and adults. The study included 20 volunteers divided into two groups: 10 adolescents aged 13-19 years (M=16.5, SD=1.65) and 10 adults aged 20-26 years (M=21.8, SD=2.04). In order to measure the contrast sensitivity at spatial frequencies of 0.6, 2.5, 5 and 20 degrees of visual angle (cpd), it was used the psychophysical method of two alternative forced choice (2AFC). A One Way ANOVA performance showed a significant difference in the comparison between groups: F [(4, 237)=3.74, p<.05]. The post-hoc Tukey HSD showed a significant difference between the frequencies of 0.6 (p <.05) and 20 cpd (p<.05). Thus, the results showed that the visual perception behaves differently with regard to the sensory mechanisms that render the contrast towards adolescents and adults. These results are useful to better characterize and comprehend human vision development.
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Resumen basado en el de la publicación
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Resumen del vídeo en catalán
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En la cub.: Secundaria. Acompañado de : Tecnología. Estructura
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Ayudas a la Innovación Educativa, 1997-98. Anexo Memoria en C-Innov. 54
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Resumen tomado de la publicaci??n
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A simple extended finite field nuclear relaxation procedure for calculating vibrational contributions to degenerate four-wave mixing (also known as the intensity-dependent refractive index) is presented. As a by-product one also obtains the static vibrationally averaged linear polarizability, as well as the first and second hyperpolarizability. The methodology is validated by illustrative calculations on the water molecule. Further possible extensions are suggested
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It is shown that Bretherton's view of baroclinic instability as the interaction of two counter-propagating Rossby waves (CRWs) can be extended to a general zonal flow and to a general dynamical system based on material conservation of potential vorticity (PV). The two CRWs have zero tilt with both altitude and latitude and are constructed from a pair of growing and decaying normal modes. One CRW has generally large amplitude in regions of positive meridional PV gradient and propagates westwards relative to the flow in such regions. Conversely, the other CRW has large amplitude in regions of negative PV gradient and propagates eastward relative to the zonal flow there. Two methods of construction are described. In the first, more heuristic, method a ‘home-base’ is chosen for each CRW and the other CRW is defined to have zero PV there. Consideration of the PV equation at the two home-bases gives ‘CRW equations’ quantifying the evolution of the amplitudes and phases of both CRWs. They involve only three coefficients describing the mutual interaction of the waves and their self-propagation speeds. These coefficients relate to PV anomalies formed by meridional fluid displacements and the wind induced by these anomalies at the home-bases. In the second method, the CRWs are defined by orthogonality constraints with respect to wave activity and energy growth, avoiding the subjective choice of home-bases. Using these constraints, the same form of CRW equations are obtained from global integrals of the PV equation, but the three coefficients are global integrals that are not so readily described by ‘PV-thinking’ arguments. Each CRW could not continue to exist alone, but together they can describe the time development of any flow whose initial conditions can be described by the pair of growing and decaying normal modes, including the possibility of a super-modal growth rate for a short period. A phase-locking configuration (and normal-mode growth) is possible only if the PV gradient takes opposite signs and the mean zonal wind and the PV gradient are positively correlated in the two distinct regions where the wave activity of each CRW is concentrated. These are easily interpreted local versions of the integral conditions for instability given by Charney and Stern and by Fjørtoft.
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The constant-density Charney model describes the simplest unstable basic state with a planetary-vorticity gradient, which is uniform and positive, and baroclinicity that is manifest as a negative contribution to the potential-vorticity (PV) gradient at the ground and positive vertical wind shear. Together, these ingredients satisfy the necessary conditions for baroclinic instability. In Part I it was shown how baroclinic growth on a general zonal basic state can be viewed as the interaction of pairs of ‘counter-propagating Rossby waves’ (CRWs) that can be constructed from a growing normal mode and its decaying complex conjugate. In this paper the normal-mode solutions for the Charney model are studied from the CRW perspective.
Clear parallels can be drawn between the most unstable modes of the Charney model and the Eady model, in which the CRWs can be derived independently of the normal modes. However, the dispersion curves for the two models are very different; the Eady model has a short-wave cut-off, while the Charney model is unstable at short wavelengths. Beyond its maximum growth rate the Charney model has a neutral point at finite wavelength (r=1). Thereafter follows a succession of unstable branches, each with weaker growth than the last, separated by neutral points at integer r—the so-called ‘Green branches’. A separate branch of westward-propagating neutral modes also originates from each neutral point. By approximating the lower CRW as a Rossby edge wave and the upper CRW structure as a single PV peak with a spread proportional to the Rossby scale height, the main features of the ‘Charney branch’ (0
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The Kelvin Helmholtz (KH) problem, with zero stratification, is examined as a limiting case of the Rayleigh model of a single shear layer whose width tends to zero. The transition of the Rayleigh modal dispersion relation to the KH one, as well as the disappearance of the supermodal transient growth in the KH limit, are both rationalized from the counterpropagating Rossby wave perspective.
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Baroclinic instability of perturbations described by the linearized primitive quations, growing on steady zonal jets on the sphere, can be understood in terms of the interaction of pairs of counter-propagating Rossby waves (CRWs). The CRWs can be viewed as the basic components of the dynamical system where the Hamiltonian is the pseudoenergy and each CRW has a zonal coordinate and pseudomomentum. The theory holds for adiabatic frictionless flow to the extent that truncated forms of pseudomomentum and pseudoenergy are globally conserved. These forms focus attention on Rossby wave activity. Normal mode (NM) dispersion relations for realistic jets are explained in terms of the two CRWs associated with each unstable NM pair. Although derived from the NMs, CRWs have the conceptual advantage that their structure is zonally untilted, and can be anticipated given only the basic state. Moreover, their zonal propagation, phase-locking and mutual interaction can all be understood by ‘PV-thinking’ applied at only two ‘home-bases’—potential vorticity (PV) anomalies at one home-base induce circulation anomalies, both locally and at the other home-base, which in turn can advect the PV gradient and modify PV anomalies there. At short wavelengths the upper CRW is focused in the mid-troposphere just above the steering level of the NM, but at longer wavelengths the upper CRW has a second wave-activity maximum at the tropopause. In the absence of meridional shear, CRW behaviour is very similar to that of Charney modes, while shear results in a meridional slant with height of the air-parcel displacement-structures of CRWs in sympathy with basic-state zonal angular-velocity surfaces. A consequence of this slant is that baroclinically growing eddies (on jets broader than the Rossby radius) must tilt downshear in the horizontal, giving rise to up-gradient momentum fluxes that tend to accelerate the barotropic component of the jet.