10,843 research outputs found
Effect of incidental teaching strategies on the workload in soccer. A systematic review.
El análisis realizado por la literatura existente acerca de los efectos que produce la utilización de estrategias de enseñanza incidentales en los atletas se ha realizado fundamentalmente bajo un prisma unidimensional, generalmente a través de los índices de rendimiento (cognitivo o motor), en términos de eficacia de las decisiones de los jugadores o de la precisión en los lanzamientos. Pero son escasos los trabajos que han estudiado el impacto de este tipo de estrategias bajo un prisma multidimensional, analizando además su efecto sobre variables de tipo fisiológico, como la frecuencia cardíaca, el movimiento ocular o el volumen máximo de oxígeno, o variables subjetivas, como el nivel de ansiedad, el rendimiento percibido o la percepción subjetiva del esfuerzo. Por todo ello, el objetivo del presente estudio es analizar bajo un prisma multidimensional el efecto de las estrategias de enseñanza incidentales sobre la carga de trabajo durante el aprendizaje de habilidades relacionadas con el fútbol, con objeto de conocer en qué aspectos benefician o perjudican el aprendizaje y el rendimiento de los jugadores. Se realizó una revisión sistemática de los estudios publicados hasta la actualidad. Se consultaron las bases de datos Web of Science, Scopus, SportDiscus with Full Text y PsycInfo, y revistas especializadas en la materia, además de realizar una revisión ascendente de la literatura seleccionada. Finalmente se seleccionaron 15 estudios. En base a los resultados obtenidos en los estudios seleccionados, en líneas generales podemos afirmar que los jugadores se ven beneficiados de una reducción de la cantidad de información que procesan intencionadamente para la resolución del problema que les plantea la tarea en habilidades relacionadas con el fútbol, siendo por tanto favorable la utilización de estrategias incidentales para dicho desempeño. No obstante, y debido a que las técnicas utilizadas para la evaluación del efecto de dicha estrategia han sido principalmente unidimensionales, se aconseja la utilización combinada de diferentes herramientas que consideren no sólo aspectos relacionados con el rendimiento, sino también medidas fisiológicas y psicológicas, con objeto de obtener una visión holística del efecto que este tipo de estrategia produce en los jugadores.The analysis made by the existing literature about the effects produced by the use of incidental teaching strategies in athletes has been carried out fundamentally under a one-dimensional prism, generally through performance indexes (cognitive or motor), in terms of efficiency of the decisions of the players or of the precision in the throws. But there are few studies that have studied the impact of this type of strategies under a multidimensional prism, also analyzing its effect on variables of physiological type, such as heart rate, eye movement or maximum volume of oxygen, or subjective variables, such as the level of anxiety, the perceived performance or the subjective perception of the effort. For all these reasons, the aim of this study is to analyze, under a multidimensional prism, the effect of incidental teaching strategies on the workload during the learning of soccer skills, in order to know in which aspects they benefit or harm learning. and the performance of the players. A systematic review of the studies published to date was carried out. We consulted the Web of Science databases, Scopus, SportDiscus with Full Text and PsycInfo, and specialized journals on the subject, as well as carrying out an upward revision of the selected literature. Finally, 15 studies were selected. Based on the results obtained in the selected studies, in general terms we can say that players benefit from a reduction in the amount of information they intentionally process to solve the problem posed by the task in soccer-related skills. being therefore favorable the use of incidental strategies for such performance. However, and because the techniques used to evaluate the effect of this strategy have been mainly one-dimensional, it is advisable to use different tools that consider not only aspects related to performance, but also physiological and psychological measures, with a view to to obtain a holistic view of the effect that this type of strategy produces on players
Dimensional analysis and Rutherford Scattering
Dimensional analysis, and in particular the Buckingham theorem is
widely used in fluid mechanics. In this article we obtain an expression for the
impact parameter from Buckingham's theorem and we compare our result with
Rutherford's original discovery found in the early twentieth century
Path integral approach to no-Coriolis approximation in heavy-ion collisions
We use the two time influence functional method of the path integral approach
in order to reduce the dimension of the coupled-channels equations for
heavy-ion reactions based on the no-Coriolis approximation. Our method is
superior to other methods in that it easily enables us to study the cases where
the initial spin of the colliding particle is not zero. It can also be easily
applied to the cases where the internal degrees of freedom are not necessarily
collective coordinates. We also clarify the underlying assumptions in our
approach.Comment: 11 pages, Latex, Phys. Rev. C in pres
Entropic Barriers, Frustration and Order: Basic Ingredients in Protein Folding
We solve a model that takes into account entropic barriers, frustration, and
the organization of a protein-like molecule. For a chain of size , there is
an effective folding transition to an ordered structure. Without frustration,
this state is reached in a time that scales as , with
. This scaling is limited by the amount of frustration which
leads to the dynamical selectivity of proteins: foldable proteins are limited
to monomers; and they are stable in {\it one} range of temperatures,
independent of size and structure. These predictions explain generic properties
of {\it in vivo} proteins.Comment: 4 pages, 4 Figures appended as postscript fil
Ultra-broadband photon pair preparation by spontaneous four wave mixing in dispersion-engineered optical fiber
We present a study of the spectral properties of photon pairs generated
through the process of spontaneous four wave mixing (SFWM) in single mode
fiber. Our analysis assumes narrowband pumps, which are allowed to be
frequency-degenerate or non-degenerate. Based on this analysis, we derive
conditions on the pump frequencies and on the fiber dispersion parameters which
guarantee the generation of ultra-broadband photon pairs. Such photon pairs are
characterized by: i) a very large degree of entanglement, and ii) a very high
degree of temporal synchronization between the signal and idler photons.
Through a numerical exercise, we find that the use of photonic crystal fiber
(PCF) facilitates the fulfilment of the conditions for ultra-broadband photon
pair generation; in particular, the spectral region in which emission occurs
can be adjusted to particular needs through an appropriate choice of the PCF
parameters. In addition, we present a novel quantum interference effect,
resulting from indistinguishable pathways to the same outcome, which can occur
when pumping a SFWM source with multiple spectral lines.Comment: 15 pages, 10 figures. To be published in Phys. Rev.
Electron and ion stagnation at the collision front between two laser produced plasmas
We report results from a combined optical interferometric and spectrally resolved imaging study on colliding laser produced aluminium plasmas. A Nomarski interferometer was used to probe the spatio-temporal distribution of electron densities at the collision front. Analysis of the resulting interferograms reveals the formation and evolution of a localized electron density feature with a well-defined profile reminiscent of a stagnation layer. Electron stagnation begins at a time delay of 10 ns after the peak of the plasma generating laser pulse. The peak electron density was found to exceed 10^19 cm^−3 and the layer remained well defined up to a time delay of ca 100 ns. Temporally and spectrally resolved optical imaging was also undertaken, to compare the Al^+ ion distribution with that of the 2D electron density profile. This revealed nascent stagnation of singly charged ions at a delay time of 20 ns. We attribute these results to the effects of space charge separation in the seed plasma plumes
Gravitomagnetism in Metric Theories: Analysis of Earth Satellites Results, and its Coupling with Spin
Employing the PPN formalism the gravitomagnetic field in different metric
theories is considered in the analysis of the LAGEOS results. It will be shown
that there are several models that predict exactly the same effect that general
relativity comprises. In other words, these Earth satellites results can be
taken as experimental evidence that the orbital angular momentum of a body does
indeed generate space--time geometry, notwithstanding they do not endow general
relativity with an outstanding status among metric theories. Additionally the
coupling spin--gravitomagnetic field is analyzed with the introduction of the
Rabi transitions that this field produces on a quantum system with spin 1/2.
Afterwards, a continuous measurement of the energy of this system is
introduced, and the consequences upon the corresponding probabilities of the
involved gravitomagnetic field will be obtained. Finally, it will be proved
that these proposals allows us, not only to confront against future experiments
the usual assumption of the coupling spin--gravotimagnetism, but also to
measure some PPN parameters and to obtain functional dependences among them.Comment: 10 page
- …