Evolution of a mass-less test scalar field on Boson Stars space-times

We numerically solve the mass-less test scalar field equation on the space-time background of boson stars and black holes. In order to do so, we use a numerical domain that contains future null infinity. We achieve this construction using a scri-fixing conformal compactification technique based on hyperboloidal constant mean curvature foliations of the space-time and solve the conformally invariant wave equation. We present two results: the scalar field shows oscillations of the quasi- normal-mode type found for black holes only for boson star configurations that are compact, and no signs of tail decay is found in the parameter space we explored. Even though our results do not correspond to the master equation of perturbations of boson star solutions, they indicate that the parameter space of boson stars as black hole mimickers is restricted to compact configurations.Comment: 9 pages, 15 eps figures, revtex

Percepción de la salud de los niños expresada en el lenguaje creativo de los dibujos

Objective. Children’s health perception through creative drawing language the identification of external factors perceived as negative or positive to health by children. Methodology. A descriptive study that describes the analysis of the expressive language of drawings and written comments. The sample consisted of 130 children in 3rd and 4th classes from four randomly selected schools, in the region of Central Portugal Continental (Coimbra district). The study was conducted during the first semester of 2011. The data collection was performed by means of Rodrigues’ drawing/writing sheet. This sheet is divided in 4 areas (2 of them to draw what children consider good for health and the other 2 to write the content or message of the drawings). The themes expressed are classified based on the priority areas for the promotion of healthy lifestyles. Results. children value healthy food, physical activity, mental health, prevention of inappropriate substance consumption and health and environment. The drawings and comments show links between diet and physical exercise, and between mental health and interpersonal relationships. Conclusion. Drawings and comments facilitate health professionals understanding of children’s perception of health positive and negative factors. The results of the study allow planning intervention strategies in school health from infant perception