RESUMO
Gamma-ray bursts (GRBs) fall into two classes: short-hard and long-soft bursts. The latter are now known to have X-ray and optical afterglows, to occur at cosmological distances in star-forming galaxies, and to be associated with the explosion of massive stars. In contrast, the distance scale, the energy scale and the progenitors of the short bursts have remained a mystery. Here we report the discovery of a short-hard burst whose accurate localization has led to follow-up observations that have identified the X-ray afterglow and (for the first time) the optical afterglow of a short-hard burst; this in turn led to the identification of the host galaxy of the burst as a late-type galaxy at z = 0.16 (ref. 10). These results show that at least some short-hard bursts occur at cosmological distances in the outskirts of galaxies, and are likely to be caused by the merging of compact binaries.
RESUMO
An exploratory study of the relation of language proficiency, behavioral difficulties, and various areas of development was conducted with 64 children ranging from 24 to 29 months of age (M = 25.7 mo.). Data were obtained through language sampling, direct developmental assessment, and maternal reports of children's development and behavior. While scores on measures of expressive language abilities were moderately predictive of scores on measures of behavior problems, a stronger association was found between indices of delayed speech and lower scores on both social and cognitive development. The results point to the centrality of language development to other developmental and behavioral milestones. Further, findings support the importance of identifying late-talking children at an early age so that remedial help may be considered.
