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Este artículo describe la estructura de las clases sociales en Guatemala en el nuevo siglo, caracterizada por una incipiente clase media, que representa menos del 20% de la población. El artículo también aborda el tema de la movilidad social en las áreas educativa y laboral.  En ambos casos la movilidad social es baja, existiendo diferencias significativas según género y grupo étnico. La movilidad de la educación es mayor en hombres que en mujeres, así como en el grupo étnico no indígena que en el indígena. En la movilidad ocupacional la situación es inversa.

With the aim of introducing a computationally efficient solution for problems such as the fast computation of magnetic field magnitudes and forces in coils and windings, this paper presents analytical expressions for the magnetic vector potential and magnetic field intensity in radial and axial directions due to a finite cylinder with infinitesimal wall thickness carrying a linearly varying current density between the values at the lower and upper ends. All expressions have been derived in terms of complete elliptic integrals of first, second and third kind, whose evaluation is achieved by means of very fast algorithms. The formulas presented make possible the fast computation of magnetic field at any point in space at reduced computational cost. The formulation is not only specially suited for modeling the current distribution in foil windings of power transformers but also for representing the magnetization of transformer core legs. The present method is also useful for efficient modeling of cylinders with constant current density since it is a generalization of this especial case. Finally, an example is presented where the results achieved using the proposed method are compared with those obtained using the finite element method showing a very good agreement between them.

A novel mesh-free axisymmetric methodology for the determination of the low-frequency current distribution in foil windings is presented in this paper. The proposed methodology applies equivalent models for the foil winding and the iron core, which are based on the field produced by elementary geometric configurations and boundary conditions derived from Maxwell's equations. Power losses in the windings due to skin effect and proximity effect are calculated with the proposed method and the finite-element method (FEM). The comparison of both results showed excellent agreement. The computational performance is also compared with FEM. It has been found that the proposed method achieves significant improvements in computational times compared with FEM retaining the level of precision required for transformer design purposes.Index Terms-Finite-element method (FEM), integral methods, proximity effect, sheet current, skin depth, skin effect.