960 research outputs found

    Effect of Metacognitive Skills Training on Metacognitive Awareness, Self-Efficacy and Academic Achievement of University Students

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    Aims: Metacognition deals with active monitoring and adjusting the results and cognitive processes to gain the purpose. Academic self-efficacy is dependent on students’ perception of learning and is an important factor in the success of students reasoning. This study aimed to determine the effectiveness of metacognitive skills training on metacognitive awareness, self-efficacy and academic achievement in university students. Materials & Methods: This semi-experimental study with a pretest-posttest controlled approach was conducted in all students of Kashan University of Medical Sciences in 2014. 50 participants were selected by cluster sampling and were randomly divided into 2 intervention and control groups. Metacognitive awareness of reading strategies inventory (MARSI) and General Self-efficacy Scale were used for data gathering. Data were analyzed using ANCOVA test. Findings: There were significant difference between the score of the pretest and posttest of the intervention group in both self-efficacy and metacognition awareness. In addition, there were significant differences between posttest scores of intervention and control groups in self-efficacy (p<0.001; F=42.46) and cognitive awareness (p<0.001; F=190.99), but there was no significant difference (p=0.072; F=3.39) in academic achievement between the intervention and control groups’ posttest scores. Conclusion: Metacognitive training affects metacognitive awareness and self-efficacy but it is not founded for academic achievement

    Cylindrical Solutions in Modified f(T) Gravity

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    We investigate static cylindrically symmetric vacuum solutions in Weyl coordinates in the framework of f(T) theories of gravity, where T is the torsion scalar. The set of modified Einstein equations is presented and the fourth coming equations are established. Specific physical expressions are assumed for the algebraic function f(T) and solutions are obtained. Moreover, general solution is obtained with finite values of u(r) on the axis r = 0, and this leads to a constant torsion scalar. Also, cosmological constant is introduced and its relation to Linet-Tian solution in GR is commented.Comment: 13 pages; Accepted for publication in International Journal of Modern Physics D (IJMPD

    A Model Predictive Decentralized Control Scheme With Reduced Communication Requirement for Spacecraft Formation

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    Massive gravity from double copy

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    We consider the double copy of massive Yang-Mills theory in four dimensions, whose decoupling limit is a nonlinear sigma model. The latter may be regarded as the leading terms in the low energy effective theory of a heavy Higgs model, in which the Higgs has been integrated out. The obtained double copy effective field theory contains a massive spin-2, massive spin-1 and a massive spin-0 field, and we construct explicitly its interacting Lagrangian up to fourth order in fields. We find that up to this order, the spin-2 self interactions match those of the dRGT massive gravity theory, and that all the interactions are consistent with a Λ3 = (m2MPl)1/3 cutoff. We construct explicitly the Λ3 decoupling limit of this theory and show that it is equivalent to a bi-Galileon extension of the standard Λ3 massive gravity decoupling limit theory. Although it is known that the double copy of a nonlinear sigma model is a special Galileon, the decoupling limit of massive Yang-Mills theory is a more general Galileon theory. This demonstrates that the decoupling limit and double copy procedures do not commute and we clarify why this is the case in terms of the scaling of their kinematic factors

    p-Wave holographic superconductors with Weyl corrections

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    We study the (3+1) dimensional p-wave holographic superconductors with Weyl corrections both numerically and analytically. We describe numerically the behavior of critical temperature TcT_{c} with respect to charge density ρ\rho in a limited range of Weyl coupling parameter γ\gamma and we find in general the condensation becomes harder with the increase of parameter γ\gamma. In strong coupling limit of Yang-Mills theory, we show that the minimum value of TcT_{c} obtained from analytical approach is in good agreement with the numerical results, and finally show how we got remarkably a similar result in the critical exponent 1/2 of the chemical potential μ\mu and the order parameter with the numerical curves of superconductors.Comment: 7 pages, 1 figure, 1 table. One refrence added, presentations improve

    Gauss-Bonnet holographic superconductors with magnetic field

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    We study the Gauss-Bonnet (GB) holographic superconductors in the presence of an external magnetic field. We describe the phenomena away from the probe limit. We derive the critical magnetic field of the GB holographic superconductors with backreaction. Our analytical approach matches the numerical calculations. We calculate the backreaction corrections up to first order of O(κ2=8πG)O(\kappa^2=8\pi G) to the critical temperature TCT_C and the critical magnetic field BCB_C for a GB superconductor. We show that the GB coupling α\alpha makes the condensation weaker but the backreaction corrections O(κ2)O(\kappa^2) make the critical magnetic field stronger.Comment: 9 pages, 4 figures. Accepted for publication by EP

    Simulating Supersonic Turbulence in Magnetized Molecular Clouds

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    We present results of large-scale three-dimensional simulations of weakly magnetized supersonic turbulence at grid resolutions up to 1024^3 cells. Our numerical experiments are carried out with the Piecewise Parabolic Method on a Local Stencil and assume an isothermal equation of state. The turbulence is driven by a large-scale isotropic solenoidal force in a periodic computational domain and fully develops in a few flow crossing times. We then evolve the flow for a number of flow crossing times and analyze various statistical properties of the saturated turbulent state. We show that the energy transfer rate in the inertial range of scales is surprisingly close to a constant, indicating that Kolmogorov's phenomenology for incompressible turbulence can be extended to magnetized supersonic flows. We also discuss numerical dissipation effects and convergence of different turbulence diagnostics as grid resolution refines from 256^3 to 1024^3 cells.Comment: 10 pages, 3 figures, to appear in the proceedings of the DOE/SciDAC 2009 conferenc

    EFT of interacting spin-2 fields

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    We consider the effective field theory of multiple interacting massive spin-2 fields. We focus on the case where the interactions are chosen so that the cutoff is the highest possible, and highlight two distinct classes of theories. In the first class, the mass eigenstates only interact through potential operators that carry no derivatives in unitary gauge at leading order. In the second class, a specific kinetic mixing between the mass eigenstates is included non-linearly. Performing a decoupling and ADM analysis, we point out the existence of a ghost present at a low scale for the first class of interactions. For the second class of interactions where kinetic mixing is included, we derive the full Λ3-decoupling limit and confirm the absence of any ghosts. Nevertheless both formulations can be used to consistently describe an EFT of interacting massive spin-2 fields which, for a suitable technically natural tuning of the EFT, have the same strong coupling scale Λ3. We identify the generic form of EFT corrections in each case. By using Galileon Duality transformations for the specific case of two massive spin-2 fields with suitable couplings, the decoupling limit theory is shown to be a bi-Galileon

    Planar photonic crystals infiltrated with nanoparticle/polymer composites

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    © 2007 American Institute of Physics. The electronic version of this article is the complete one and can be found at: http://dx.doi.org/10.1063/1.2817964DOI: 10.1063/1.2817964Infiltration of planar two-dimensional silicon photonic crystals with nanocomposites using a simple yet effective melt processing technique is presented. The nanocomposites that were developed by evenly dispersing functionalized TiO₂ nanoparticles into a photoconducting polymer were completely filled into photonic crystals with hole sizes ranging from 90 to 500 nm. The infiltrated devices show tuning of the photonic band gap that is controllable by the adjustment of the nanoparticle loading level. These results may be useful in the development of tunable photonic crystal based devices and hybrid light emitting diodes and solar cells
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