Association of Drug and Alcohol Use With Adolescent Firearm Homicide at Individual, Family, and Neighborhood Levels.

Importance: Homicide is the third leading cause of death for adolescents in the United States and the leading cause of death for adolescents who are African American. Large cities have disproportionate homicide rates.

Objective: To determine the relationships between exposures to drugs and alcohol at the individual, family, and neighborhood levels and adolescent firearm homicide and to inform new approaches to preventing firearm violence.

The effect of the hiv/aids epidemic on africa's truck drivers.

The AIDS epidemic is having a growing impact on the transport sector of the economy of sub-Saharan Africa, where long-distance truck drivers are at an increased risk of infection due to their frequent contacts with commercial sex workers. The spread of AIDS in the transport industry is especially significant to the economy, as truck drivers are largely responsible for transporting crops and supplies needed for daily subsistence. In this paper we analyze these effects via two models, one employing a switch and the other a Verhulst saturation function, to describe the rate at which new drivers are recruited in terms of the supply and demand for them in the general population.