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Search Results: 1 - 10 of 7832 matches for " Alfredo Macías "
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Rese a de "Aguas de La Coru a 1903-2003. Cien a os al servicio de la ciudad" de ALBERTE MARTíNEZ [dir.], LUIS GIADáS, JESúS MIRáS, CARLOS PI EIRO, GUSTAVO REGO
Revista Galega de Economía , 2009,
Rese a de "La industria del gas en Galicia: del alumbrado por gas al siglo XXI, 1 850-2005" de A. MARTíNEZ [coord.], J. MIRáS, E. LINDOSO
Revista Galega de Economía , 2011,
Una aproximación teórica al desarrollo endógeno
Alfredo Macías,Gonzalo Saavedra
Cultura-Hombre-Sociedad , 2004, DOI: 10.7770/cuhso-v8n1-art203
Abstract: Este trabajo propone una reflexión teórica y conceptual acerca del desarrollo como proceso endógeno. La viabilidad de tal perspectiva depende, en gran medida, de si se asume o no su construcción a partir de la vida comunitaria como espacio de subjetividad. La tarea es compleja pero posible, pues parece depender de las propias comunidades y de sus capacidades para sobreponer sus facultades reflexivas a un ethos racionalista,propio de una civilización que progresivamente niega y desestima sus dimensiones morales y afectivas. Es necesario entonces superar el fatalismo determinista de lo estructural, el reto del desarrollo endógeno es, en primer término, subjetivo y humano.
Generalized Reissner-Nordstr?m solution in Metric-Affine Gravity
Alfredo Macías,José Socorro
Physics , 1999, DOI: 10.1088/0264-9381/16/7/312
Abstract: We present the generalized Reissner-Nordstr\"om solution of the field equations of metric-affine gravity (MAG), endowed with electric and magnetic charges, as well as with gravito-electric and gravito-magnetic charges and a cosmological constant term. Moreover, the case $M=e_o$, i.e. mass equal to electric charge and $\lambda=0$, corresponds to an electrically and magnetically charged monopole. Also further multipole solutions are obtained. The charge assignments of the solutions is discussed.
A method for generating Gowdy cosmological models
Sánchez, Alberto;Macías, Alfredo;Quevedo, Hernando;
Revista mexicana de física , 2007,
Abstract: numerical methods have been extensively used to investigate gowdy models, but only recently it has been argued that solutions-generating techniques can be applied in this case to generate new solutions. in this work, we concentrate on t3 gowdy cosmological models and shall see that a complex coordinate transformation, together with a complex change of metric functions, allows us to apply, in a straightforward manner, the well-known solution-generating techniques that have been intensively used for stationary axisymmetric solutions.
A method for generating Gowdy cosmological models
Alberto Sánchez,Alfredo Macías,Hernando Quevedo
Revista mexicana de física , 2007,
Abstract: M′etodos num′ericos han sido extensamente usados para investigar modelos de Gowdy, pero s ′olo recientemente se ha propuesto que las t′ecnicas de generaci′on de soluciones pueden ser aplicadas en ′este caso para generar nuevas soluciones. En este trabajo nos concentraremos en los modelos cosmol′ogicos de Gowdy T3 y mostraremos como una transformaci′on coordenada compleja junto con un cambio complejo de las funciones m′etricas nos permite aplicar de una manera sencilla las t′ecnicas de generaci′on de soluciones que han sido extensamente usadas para soluciones estacionarias axisim′etricas.
Supersymmetric quantum cosmology for Bianchi class A models
Alfredo Macías,Eckehard W. Mielke,José Socorro
Physics , 1997, DOI: 10.1142/S0218271898000462
Abstract: The canonical theory of (N=1) supergravity, with a matrix representation for the gravitino covector-spinor, is applied to the Bianchi class A spatially homogeneous cosmologies. The full Lorentz constraint and its implications for the wave function of the universe are analyzed in detail. We found that in this model no physical states other than the trivial "rest frame" type occur.
Multipole solutions in metric--affine gravity
José Socorro,Claus L?mmerzahl,Alfredo Macías,Eckehard W. Mielke
Physics , 1998, DOI: 10.1016/S0375-9601(98)00360-0
Abstract: Above Planck energies, the spacetime might become non--Riemannian, as it is known fron string theory and inflation. Then geometries arise in which nonmetricity and torsion appear as field strengths, side by side with curvature. By gauging the affine group, a metric affine gauge theory emerges as dynamical framework. Here, by using the harmonic map ansatz, a new class of multipole like solutions in the metric affine gravity theory (MAG) is obtained.
Effective Weinberg--Salam Model From Higher Dimensions
Alfredo Macías,Abel Camacho,Eckehard W. Mielke,Tonatiuh Matos
Physics , 1996,
Abstract: We consider an 8--dimensional gravitational theory, which possesses a principle fiber bundle structure, with Lorentz--scalar fields coupled to the metric. One of them plays the role of a Higgs field and the other one that of a dilaton field. The effective cosmological constant is interpreted as a Higgs potential. The Yukawa couplings are introduce by hand. The extra dimensions constitute a $SU(2)_{L} \times U(1)_{Y} \times SU(2)_{R}$ group manifold. Dirac fields are coupled to the potentials derived from the metric. As result, we obtain an effective four--dimensional theory which contains all couplings of a Weinberg--Salam--Glashow theory in a curved space-time. The masses of the gauge bosons and of the first two fermion families are given by the theory.
Exact solution for a binary system of unequal counter-rotating black holes
I. Cabrera-Munguia,Claus L?mmerzahl,Alfredo Macías
Physics , 2013, DOI: 10.1088/0264-9381/30/17/175020
Abstract: A complete solution describing a binary system constituted by two unequal counter-rotating black holes with a massless strut inbetween is presented. It is expressed in terms of four arbitrary parameters: the half length of the two rods representing the black hole horizons sigma1 and sigma2, the total mass M, and the relative distance R between the centers of the horizons. The explicit form of this solution in terms of physical parameters, i.e., the Komar masses M1 and M2, the Komar angular momenta per unit mass a1 and a2, having a1 and a2 opposite signs, and the coordinate distance R, led us to a 4-parameter subclass of solutions in which a set of five physical parameters satisfy a simple algebraic relation. Moreover, the interaction force, provided by the strut, between the black holes results to be of same form as it is for the static double-Schwarzschild case.
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