Quantitative Risk Assessment of Norovirus Transmission in Food Establishments: Evaluating the Impact of Intervention Strategies and Food Employee Behavior on the Risk Associated with Norovirus in Foods

We developed a quantitative risk assessment model using a discrete event framework to quantify and study the risk associated with norovirus transmission to consumers through food contaminated by infected food employees in a retail food setting. This study focused on the impact of ill food workers experiencing symptoms of diarrhea and vomiting and potential control measures for the transmission of norovirus to foods. The model examined the behavior of food employees regarding exclusion from work while ill and after symptom resolution and preventive measures limiting food contamination during preparation. The mean numbers of infected customers estimated for 21 scenarios were compared to the estimate for a baseline scenario representing current practices. Results show that prevention strategies examined could not prevent norovirus transmission to food when a symptomatic employee was present in the food establishment. Compliance with exclusion from work of symptomatic food employees is thus critical, with an estimated range of 75–226% of the baseline mean for full to no compliance, respectively. Results also suggest that efficient handwashing, handwashing frequency associated with gloving compliance, and elimination of contact between hands, faucets, and door handles in restrooms reduced the mean number of infected customers to 58%, 62%, and 75% of the baseline, respectively. This study provides quantitative data to evaluate the relative efficacy of policy and practices at retail to reduce norovirus illnesses and provides new insights into the interactions and interplay of prevention strategies and compliance in reducing transmission of foodborne norovirus.     

Social process theory of emotion: A dynamic systems approach

In this paper we apply a dynamic systems perspective to infant emotional development. We propose that emotions are not states but self-organizing dynamic processes intimately tied to the flow of an individual's activity in a context. We review data on the relationship between emotional actions and the social context, in particular the development of smiling and laughter. These data are more adequately explained by our perspective than by other theories of emotional development. We provide a model for how emotional processes in early infancy become embedded into sociocultural systems, and suggest new avenues of research on emotional development.     

A nonparametric test to compare survival distributions with covariate adjustment

Summary.  The analysis of covariance is a technique that is used to improve the power of a k -sample test by adjusting for concomitant variables. If the end point is the time of survival, and some observations are right censored, the score statistic from the Cox proportional hazards model is the method that is most commonly used to test the equality of conditional hazard functions. In many situations, however, the proportional hazards model assumptions are not satisfied. Specifically, the relative risk function is not time invariant or represented as a log-linear function of the covariates. We propose an asymptotically valid k -sample test statistic to compare conditional hazard functions which does not require the assumption of proportional hazards, a parametric specification of the relative risk function or randomization of group assignment. Simulation results indicate that the performance of this statistic is satisfactory. The methodology is demonstrated on a data set in prostate cancer.     

A multimedia case based approach to the study of office ergonomics

Multimedia technology has the capacity to provide students with an interactive approach to problem based learning and to bridge the gap between theoretical knowledge and clinical practice. The present paper describes the design and development of the program ErgoROM, a CD which presents a case study to assist occupational therapy students in their studies of office ergonomics. A pilot study showed that overall, 91% of respondents rated the ErgoROM as either "Excellent" or "Very Good". Additionally they reported that ErgoROM had a positive impact on active learning and critical thinking.     

Men's influence on the onset and progress of fertility decline in Ghana, 1988-98

While lower fertility is commonly associated with women's reproductive autonomy, we demonstrate that the influence of men's education on reproductive decision-making increased during the first decade of rapid fertility decline in Ghana. Husband's education exerts a stronger influence on wife's fertility intentions than does her own education, and the magnitude of the effect of his education increased significantly from 1988 to 1998. Lower fertility in Ghana seems to be associated more with men's declining fertility desires than with women's increasing reproductive autonomy. Nevertheless, there is some indication that women's education may play a relatively greater role in reproductive decision-making as fertility decline progresses still further.     

Alcohol consumption, alcohol-related problems, and other substance use among lesbian and bisexual women

Relationships between sexual orientation and a wide range of substance use and problem variables were examined based on data from the 2000 National Alcohol Survey. Lesbians, bisexuals, and heterosexually identified women who report same-sex partners were compared to exclusively heterosexual women in relation to alcohol consumption, use of tobacco and other drugs, bar-going, alcohol-related problems, and past substance abuse treatment. Substance use patterns were complex and varied between sexual orientation groups. These differences underscore the importance of developing lesbian- and bisexual-sensitive prevention and treatment services and of including measures of sexual orientation identity and behavior in population-based surveys.     

The Cox Proportional Hazards Model with a Partly Linear Relative Risk Function

The conventional Cox proportional hazards regression model contains a loglinear relative risk function, linking the covariate information to the hazard ratio with a finite number of parameters. A generalization, termed the partly linear Cox model, allows for both finite dimensional parameters and an infinite dimensional parameter in the relative risk function, providing a more robust specification of the relative risk function. In this work, a likelihood based inference procedure is developed for the finite dimensional parameters of the partly linear Cox model. To alleviate the problems associated with a likelihood approach in the presence of an infinite dimensional parameter, the relative risk is reparameterized such that the finite dimensional parameters of interest are orthogonal to the infinite dimensional parameter. Inference on the finite dimensional parameters is accomplished through maximization of the profile partial likelihood, profiling out the infinite dimensional nuisance parameter using a kernel function. The asymptotic distribution theory for the maximum profile partial likelihood estimate is established. It is determined that this estimate is asymptotically efficient; the orthogonal reparameterization enables employment of profile likelihood inference procedures without adjustment for estimation of the nuisance parameter. An example from a retrospective analysis in cancer demonstrates the methodology.