Variable Very-High-Energy Gamma-Ray Emission from the Microquasar LS I +61 303

Microquasars are binary star systems with relativistic radio-emitting jets. They are potential sources of cosmic rays and can be used to elucidate the physics of relativistic jets. We report the detection of variable gamma-ray emission above 100 gigaelectron volts from the microquasar LS I 61 + 303. Six orbital cycles were recorded. Several detections occur at a similar orbital phase, which suggests that the emission is periodic. The strongest gamma-ray emission is not observed when the two stars are closest to one another, implying a strong orbital modulation of the emission or absorption processes.

[Risk factors for maternal and infant health in adolescent mothers in Colombia]

It is a documented fact that teenage mothers have worse maternal and child health indicators than older ones. Thus, the purpose of this paper was to investigate some maternal characteristics (biological and behavioral) that could affect their childrens' health. With information derived from the 1990 Prevalence, Demographic, and Health survey, we studied all children under 5 (n = 4,971) and their respective mothers. Independent variables were age (at the time of the survey), marital status, urban or rural residence, socioeconomic bracket, and parity; dependent variables were low birth weight, prenatal care, early prenatal care, and having a vaccination card. We found that in Colombia most pregnant women were receiving prenatal care from a physician or no prenatal care; very few were under care by a traditional birth attendant, nurse, or other type of health worker. The odds of having a low birth weight infant were higher among pregnant teenagers than among women between the ages of 20 and 24 years. Notwithstanding, these two groups of women showed similar results in terms of behavioral variables (prenatal care, early prenatal care, and having a vaccination card). On the other hand, these indicators were better among married mothers as opposed to those who were unwed, widowed, separated, living with a partner out of wedlock, or divorced. In short, teenage pregnancy should be viewed as high risk not only because of the poor development of the reproductive organs, but also because of behavioral considerations. The risk is even higher when the future mother is legally married, has two or more children, does not live in an urban environment, has a low income, and has little formal education.