Social risk factors in Spanish youth and their impact on self-concept construction

This paper presents evidence from a psychosocial framework about the relationship among youth, work, and identity construction. The aims of this research were twofold. The first one was to analyze the working conditions of Spanish youth and their impact on individuals' biographies. The second one was to examine the effect of labor-related variables on construction / change of identity elements in Spanish youth. For this purpose, two research techniques were used: the Delphi method (103 experts sample from several entities and organizations closely related to our topic) and deep interviews (15 interviews with youths classified according to their relationship with the work market). Copyright 2007 by The Spanish Journal of Psychology.

Dual self-image technique for beam collimation

We propose an accurate technique for obtaining highly collimated beams, which also allows testing the collimation degree of a beam. It is based on comparing the period of two different self-images produced by a single diffraction grating. In this way, variations in the period of the diffraction grating do not affect to the measuring procedure. Self-images are acquired by two CMOS cameras and their periods are determined by fitting the variogram function of the self-images to a cosine function with polynomial envelopes. This way, loss of accuracy caused by imperfections of the measured self-images is avoided. As usual, collimation is obtained by displacing the collimation element with respect to the source along the optical axis. When the period of both self-images coincides, collimation is achieved. With this method neither a strict control of the period of the diffraction grating nor a transverse displacement, required in other techniques, are necessary. As an example, a LED considering paraxial approximation and point source illumination is collimated resulting a resolution in the divergence of the beam of σ φ = ± μrad.