Infectious disease mortality among adults by race and socioeconomic status: metropolitan Ohio, 1989-1991

The data presented here are part of an on-going longitudinal study of the relationship between socioeconomic status and mortality in the major metropolitan centers of Ohio. Using a Standardized Mortality Ratio, we find that mortality in the seven-city urban aggregate exceeds that of the rest of the state by 39 per cent for the nonwhite population and only 1 per cent for the white population. Further, for the nonwhite population, living in a high income area has no discernible health benefit for nonwhites as compared to whites. On the other hand, for the AIDS virus, there is a clear inverse association between economic status and mortality from AIDS. It is clear that the interrelationship among race, economic status, and health continues to be a complex one on which further research is needed.     

The changing nature of user attitudes toward virtual world technology: A longitudinal study

Virtual world technologies have been utilized in gaming for a number of years but only recently have they been applied as a serious tool for business. Many business applications have been identified, including the use of virtual worlds for team collaboration, training, and education, but a question remains about whether users will accept the premise that virtual worlds represent useful environments for engaging in business functions. We address this question by examining user reactions to virtual worlds. The first study looks at attitudes of users of the virtual world Second Life during three time periods (i.e., before exposure to the environment, after an information session and discussion of Second Life, and after use of the environment). Two variables, user acceptance of virtual world technologies and user self-efficacy, were examined as the primary dependent measures. Results show that while self-efficacy increases over time, user acceptance decreases in a highly correlated pattern. A second study investigates the underlying causes of the observed pattern of user acceptance using a content analysis of written reflections of user experiences. Both studies paint a detailed picture of user intentions and some of the reasons these intentions developed after use. The paper concludes with a discussion of the implications of these results for business managers and researchers.     

Multivariable singularly perturbed feedback systems with time delay

Multivariable singularly perturbed systems with both small and large time delays in the feedback loop are considered. Conditions for stability of the full-order closed-loop system are given in terms of properties of the slow and fast subsystems.     

PRELIMINARY FINDINGS THAT KEROSENE ALTERS THE DISTRIBUTION OF TOPICALLY APPLIED BENZO[A]PYRENE IN MICE

The dermal route is important in occupational exposure to polycyclic aromatic compounds (PACs), but other organs may be affected. We reported that kerosene-cleaning following treatment with used engine oil increased DNA adducts in the lungs of mice viz. animals treated with used oil alone. To determine the mechanism we topically applied ³ H-BAP(100 nmol in 25 μL acetone) and washed half the mice with 25 μL kerosene 1 h after carcinogen application. Groups of four mice were sacrificed from 1 to 72 h after treatment. Lung, liver, and skin were harvested. The fraction of the radiolabel remaining in the skin of animals treated with benzo[a]pyrene (BAP) and washed with kerosene was significantly less than those not washed, beginning at 24 h (p < .05). Fractional distribution to the lungs and livers of these animals became significantly elevated. Kerosene increased transdermal water loss. Kerosene treatment compromises dermal barrier function, enhances carcinogen absorption, and alters organ distribution.     

Frequency domain results for systems with multiple time scales

The mathematical treatment of systems with multiple time scales has traditionally employed the use of singular perturbation theory for differential equations. This paper treats such systems from a frequency-domain viewpoint. Previously existing two-frequency-scale results, involving approximation and algebraic characterization, are extended. In addition, an exact frequency-scale decomposition is presented.