962 resultados para Quantization of the scalar field and particle Creation


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The work plan aims at deepening the analysis of the theoretic assumptions which support the practice in Vocational Guidance: analyzing the incidence of endogenous and exogenous factors both in the election and studying of a particular course of study and in the occupational resolution of the graduate. This analysis enables the revision and the new theoretic conceptualization which is afterwards transferred to the course, and to different groups and provincial institutions where the practice of Vocational Guidance occurs, as well as to other schools in the Northwest provinces of Argentina. Semiotic analysis, statistical elaboration and the research-action approach which, while surveying data renders a service to the milieu, provide the base for the project. Said project focuses on the following individuals: 1) freshmen, who offer us the following aspects to be considered: a) factors which either favor or hinder the insertion of the students attending the first years of the course; b) the conditions making up the learning situation in each subject, from the teaching point of view; c) the influence of institutional dimension in the insertion process; 2) graduands: the characteristics of the situation following graduation from University, those of the labor field and the different ways of gaining access to it are investigated. This analysis is carried out in the courses of study of Psychology and English (education of Professionals in English and English for Professionals).

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The work plan aims at deepening the analysis of the theoretic assumptions which support the practice in Vocational Guidance: analyzing the incidence of endogenous and exogenous factors both in the election and studying of a particular course of study and in the occupational resolution of the graduate. This analysis enables the revision and the new theoretic conceptualization which is afterwards transferred to the course, and to different groups and provincial institutions where the practice of Vocational Guidance occurs, as well as to other schools in the Northwest provinces of Argentina. Semiotic analysis, statistical elaboration and the research-action approach which, while surveying data renders a service to the milieu, provide the base for the project. Said project focuses on the following individuals: 1) freshmen, who offer us the following aspects to be considered: a) factors which either favor or hinder the insertion of the students attending the first years of the course; b) the conditions making up the learning situation in each subject, from the teaching point of view; c) the influence of institutional dimension in the insertion process; 2) graduands: the characteristics of the situation following graduation from University, those of the labor field and the different ways of gaining access to it are investigated. This analysis is carried out in the courses of study of Psychology and English (education of Professionals in English and English for Professionals).

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The work plan aims at deepening the analysis of the theoretic assumptions which support the practice in Vocational Guidance: analyzing the incidence of endogenous and exogenous factors both in the election and studying of a particular course of study and in the occupational resolution of the graduate. This analysis enables the revision and the new theoretic conceptualization which is afterwards transferred to the course, and to different groups and provincial institutions where the practice of Vocational Guidance occurs, as well as to other schools in the Northwest provinces of Argentina. Semiotic analysis, statistical elaboration and the research-action approach which, while surveying data renders a service to the milieu, provide the base for the project. Said project focuses on the following individuals: 1) freshmen, who offer us the following aspects to be considered: a) factors which either favor or hinder the insertion of the students attending the first years of the course; b) the conditions making up the learning situation in each subject, from the teaching point of view; c) the influence of institutional dimension in the insertion process; 2) graduands: the characteristics of the situation following graduation from University, those of the labor field and the different ways of gaining access to it are investigated. This analysis is carried out in the courses of study of Psychology and English (education of Professionals in English and English for Professionals).

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In this paper, we analyze the action of the gravitational field on the dynamical Casimir effect. We consider a massless scalar field confined in a cuboid cavity placed in a gravitational field described by a static and diagonal metric. With one of the plane mirrors of the cavity allowed to move, we compute the average number of particles created inside the cavity by means of the Bogoliubov coefficients computed through perturbative expansions. We apply our result to the case of an oscillatory motion of the mirror, assuming a weak gravitational field described by the Schwarzschild metric. The regime of parametric amplification is analyzed in detail, demonstrating that our computed result for the mean number of particles created agrees with specific associated cases in the literature. Our results, obtained in the framework of the perturbation theory, are restricted, under resonant conditions, to a short-time limit.

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We study the behavior of the renormalized sextic coupling at the intermediate and strong coupling regime for the phi(4) theory defined in d = 2 dimensions. We found a good agreement with the results obtained by the field-theoretical renormalization-group in the Ising limit. In this work we use the lattice regularization method.

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We investigate the effect of the calar-isovector delta-meson field on the equation of state (EOS) and composition of hyperonic neutron star matter, and the properties of hyperonic neutron stars within the frame work of the relativistic mean field theory. The influence of the delta-field turns out to be quite different and generally weaker for hyperonic neutron star matter as compared to that for npe mu neutron star matter. We find that inclusion of the delta-field enhances the strangeness content slightly and consequently moderately softens the EOS of neutron star matter in its hyperonic phase. As for the composition of hyperonic star matter, the effect of the delta-field is shown to shift the onset of the negatively-charged (positively-charged) hyperons to slightly lower (higher) densities and to enhance (reduce) their abundances. The influence of the delta-field on the maximum mass of hyperonic neutron stars is found to be fairly weak, where as inclusion of the delta-field turns out to enhance sizably both the radii and the moments of inertia of neutron stars with given masses. It is also shown that the effects of the delta-field on the properties of hyperonic neutron stars remain similar in the case of switching off the Sigma hyperons.

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Spatial and temporal fluctuations in the concentration field from an ensemble of continuous point-source releases in a regular building array are analyzed from data generated by direct numerical simulations. The release is of a passive scalar under conditions of neutral stability. Results are related to the underlying flow structure by contrasting data for an imposed wind direction of 0 deg and 45 deg relative to the buildings. Furthermore, the effects of distance from the source and vicinity to the plume centreline on the spatial and temporal variability are documented. The general picture that emerges is that this particular geometry splits the flow domain into segments (e.g. “streets” and “intersections”) in each of which the air is, to a first approximation, well mixed. Notable exceptions to this general rule include regions close to the source, near the plume edge, and in unobstructed channels when the flow is aligned. In the oblique (45 deg) case the strongly three-dimensional nature of the flow enhances mixing of a scalar within the canopy leading to reduced temporal and spatial concentration fluctuations within the plume core. These fluctuations are in general larger for the parallel flow (0 deg) case, especially so in the long unobstructed channels. Due to the more complex flow structure in the canyon-type streets behind buildings, fluctuations are lower than in the open channels, though still substantially larger than for oblique flow. These results are relevant to the formulation of simple models for dispersion in urban areas and to the quantification of the uncertainties in their predictions.

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We present a rigorous, regularization-independent local quantum field theoretic treatment of the Casimir effect for a quantum scalar field of mass mu not equal 0 which yields closed form expressions for the energy density and pressure. As an application we show that there exist special states of the quantum field in which the expectation value of the renormalized energy-momentum tensor is, for any fixed time, independent of the space coordinate and of the perfect fluid form g(mu,nu)rho with rho > 0, thus providing a concrete quantum field theoretic model of the cosmological constant. This rho represents the energy density associated to a state consisting of the vacuum and a certain number of excitations of zero momentum, i.e., the constituents correspond to lowest energy and pressure p <= 0. (C) 2009 Elsevier Inc. All rights reserved.

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This study demonstrates the cultural dimension and the surrounding environment of different entrepreneurs selected from three countries, the United States of America, the Federative Republic of Brazil, and the United Arab Emirates. The general objective is to understand the difference in the entrepreneurial motives and spirit towards venture creation from the three different countries. After conducting field research and collecting the required data, a deep analysis was conducted to draw a comparison between the three cultures from an individual’s point of view, to help shape a set of proposed recommendations, which could be used to improve the current culture of entrepreneurship in the UAE.

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In this work we show how to define the action of a scalar field such that the Robin boundary condition is implemented dynamically, i.e. as a consequence of the stationary action principle. We discuss the quantization of that system via functional integration. Using this formalism, we derive an expression for the Casimir energy of a massless scalar field under Robin boundary conditions on a pair of parallel plates, characterized by constants c(1) and c(2). Some special cases are discussed; in particular, we show that for some values of cl and c(2) the Casimir energy as a function of the distance between the plates presents a minimum. We also discuss the renormalization at one-loop order of the two-point Green function in the philambda(4) theory subject to the Robin boundary condition on a plate.

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The Hamiltonian formulation of the teleparallel equivalent of general relativity is considered. Definitions of energy, momentum and angular momentum of the gravitational field arise from the integral form of the constraint equations of the theory. In particular, the gravitational energy-momentum is given by the integral of scalar densities over a three-dimensional spacelike hypersurface. The definition for the gravitational energy is investigated in the context of the Kerr black hole. In the evaluation of the energy contained within the external event horizon of the Kerr black hole, we obtain a value strikingly close to the irreducible mass of the latter. The gravitational angular momentum is evaluated for the gravitational field of a thin, slowly rotating mass shell. © 2002 The American Physical Society.

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This work comprises a study upon the quantization and the renormalizability of the generalized electrodynamics of spinless charged particles (mesons), namely, the generalized scalar electrodynamics (GSQED4). The theory is quantized in the covariant framework of the Batalin-Fradkin-Vilkovisky method. Thereafter, the complete Green's functions are obtained through functional methods and a proper discussion on the theory's renormalizability is also given. Next, we present the computation and further discussion on the radiative correction at α order; and, as it turns out, an unexpected mP-dependent divergence on the mesonic sector of the theory is found. Furthermore, in order to show the effectiveness of the renormalization procedure on the present theory, we also give a diagrammatic discussion on the photon self-energy at α2 order, where we observe contributions from the meson self-energy function. Afterwards, we present the expressions of the counterterms and effective coupling of the theory, obtaining from the latter an energy range where the theory is defined by m2≤k2the new divergence is absorbed suitably by the mass counterterm δZ0, showing therefore that the gauge Ward-Fradkin-Takahashi identities are satisfied still. © 2013 American Physical Society.

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We studied the low energy motion of particles in the general covariant. version of Horava-Lifshitz gravity proposed by Horava and Melby-Thompson. Using a scalar field coupled to gravity according to the minimal substitution recipe proposed by da Silva and taking the geometrical optics limit, we could write an effective relativistic metric for a general solution. As a result, we discovered that the equivalence principle is not in general recovered at low energies, unless the spatial Laplacian of A vanishes. Finally, we analyzed the motion on the spherical symmetric solution proposed by Horava and Melby-Thompson, where we could find its effective line element and compute spin-0 geodesics. Using standard methods we have shown that such an effective metric cannot reproduce Newton's gravity law even in the weak gravitational field approximation. (C) 2011 Elsevier B.V All rights reserved.

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Two-stroke outboard boat engines using total loss lubrication deposit a significant proportion of their lubricant and fuel directly into the water. The purpose of this work is to document the velocity and concentration field characteristics of a submerged swirling water jet emanating from a propeller in order to provide information on its fundamental characteristics. The properties of the jet were examined far enough downstream to be relevant to the eventual modelling of the mixing problem. Measurements of the velocity and concentration field were performed in a turbulent jet generated by a model boat propeller (0.02 m diameter) operating at 1500 rpm and 3000 rpm in a weak co-flow of 0.04 m/s. The measurements were carried out in the Zone of Established Flow up to 50 propeller diameters downstream of the propeller, which was placed in a glass-walled flume 0.4 m wide with a free surface depth of 0.15 m. The jet and scalar plume development were compared to that of a classical free round jet. Further, results pertaining to radial distribution, self similarity, standard deviation growth, maximum value decay and integral fluxes of velocity and concentration were presented and fitted with empirical correlations. Furthermore, propeller induced mixing and pollutant source concentration from a two-stroke engine were estimated.