RESUMO
The current paradigm of star formation through accretion disks, and magnetohydrodynamically driven gas ejections, predicts the development of collimated outflows, rather than expansion without any preferential direction. We present radio continuum observations of the massive protostar W75N(B)-VLA 2, showing that it is a thermal, collimated ionized wind and that it has evolved in 18 years from a compact source into an elongated one. This is consistent with the evolution of the associated expanding water-vapor maser shell, which changed from a nearly circular morphology, tracing an almost isotropic outflow, to an elliptical one outlining collimated motions. We model this behavior in terms of an episodic, short-lived, originally isotropic ionized wind whose morphology evolves as it moves within a toroidal density stratification.
RESUMO
The circulatory levels of hemoglobin and the frequency of anemia were determined in a representative sample of children with a mean age of 6.7 years. A random sample of 500 children of the city of Durango was studied. Durango has an altitude of 1893 m above sea level. The mean value of hemoglobin was 12.57 g/100 ml, with a range of 9.4 to 15.0 and a SE of 0.05. There was no difference statistically significant between the sexes. Considering 12.0 as the lower normal limit for hemoglobin values, it was found that 16% of the children were anemic, 49% of the anemic children were iron deficient, with iron serum levels of less than 60 ug/100 ml. The relationship between anemia and number of living children, birth order and weight was established. The frequency of anemia was higher among children coming from families with 4 or more living children.