On the Effect of Probability Distributions of Input Variables in Public Health Risk Assessment

A central part of probabilistic public health risk assessment is the selection of probability distributions for the uncertain input variables. In this paper, we apply the first-order reliability method (FORM)^(1–3) as a probabilistic tool to assess the effect of probability distributions of the input random variables on the probability that risk exceeds a threshold level (termed the probability of failure) and on the relevant probabilistic sensitivities. The analysis was applied to a case study given by Thompson et al. ⁽⁴⁾ on cancer risk caused by the ingestion of benzene contaminated soil. Normal, lognormal, and uniform distributions were used in the analysis. The results show that the selection of a probability distribution function for the uncertain variables in this case study had a moderate impact on the probability that values would fall above a given threshold risk when the threshold risk is at the 50th percentile of the original distribution given by Thompson et al. ⁽⁴⁾ The impact was much greater when the threshold risk level was at the 95th percentile. The impact on uncertainty sensitivity, however, showed a reversed trend, where the impact was more appreciable for the 50th percentile of the original distribution of risk given by Thompson et al. ⁴ than for the 95th percentile. Nevertheless, the choice of distribution shape did not alter the order of probabilistic sensitivity of the basic uncertain variables.     

SIMULTANEOUS BATCHING AND SCHEDULING FOR CHEMICAL PROCESSING WITH EARLINESS AND TARDINESS PENALTIES

We consider the problem of determining the allocation of demand from different customer orders to production batches and the schedule of resulting batches to minimize the total weighted earliness and tardiness penalties in context of batch chemical processing. The problem is formulated as a mixed-integer nonlinear programming model. An iterative heuristic procedure that makes use of the network nature of the problem formulation is presented to approximate an optimal solution. An algorithm polynomial in the number of batches to produce is also presented that optimally solves the problem under special cost structures.     

First-Order Reliability Analysis of Public Health Risk Assessment

This paper demonstrates a new methodology for probabilistic public health risk assessment using the first-order reliability method. The method provides the probability that incremental lifetime cancer risk exceeds a threshold level, and the probabilistic sensitivity quantifying the relative impact of considering the uncertainty of each random variable on the exceedance probability. The approach is applied to a case study given by Thompson et al. ⁽¹⁾ on cancer risk caused by ingestion of benzene-contaminated soil, and the results are compared to that of the Monte Carlo method. Parametric sensitivity analyses are conducted to assess the sensitivity of the probabilistic event with respect to the distribution parameters of the basic random variables, such as the mean and standard deviation. The technique is a novel approach to probabilistic risk assessment, and can be used in situations when Monte Carlo analysis is computationally expensive, such as when the simulated risk is at the tail of the risk probability distribution.     

Does Modernity Lead to Greater Well-Being? Bedouin Women Undergoing a Socio-Cultural Transition

The effect of modernization on the well-being of Bedouin women (n = 150) was investigated. Results show that the more modern the objective circumstances of the women's lives, and/or the more modern the husbands' attitudes (as perceived by their wives), the greater their subjective well-being(SWB). The women's own attitudes affected their SWB only via interaction with their husbands' attitudes and/or life circumstances. If the husbands' attitudes were modern, their wives' attitudes were not significantly related to SWB. However, if the husbands' attitudes were traditional, then the more modern the wives' attitudes, the lower their SWB. These findings repeated themselves, to a lesser degree, with life circumstances. The results fit the latest theoretical developments on SWB, and reflect the changes taking place within Bedouin society.     

The experiences of grandparents who have limited or no contact with their grandchildren

Purpose of the studyThe matrilineal advantage theory suggests that paternal grandparents are more at risk of having little or no contact with their grandchildren. However, there is significant family diversity within Australia and we wished to understand the experiences of a wide range of grandparents in order to determine if the matrilineal theory can be effectively used in practice to identify those grandparents most at risk for estrangement.Design and methodsA convenience group of grandparents with little or no contact with grandchildren (n = 38) told their stories in their own words using narratives obtained through interview or writing.Results and implicationsWe found that paternal grandparents, as per the matrilineal advantage theory, were more likely to be estranged from their grandchildren when their son divorced, particularly when he was not the resident parent or when he re-partnered. However, in contrast, we found that maternal grandparents who experienced conflict in their relationship with their daughter were also at risk for estrangement. This occurred even when grandparents had previously been highly involved in the lives of their grandchildren. Some estrangements appeared to result from a cultural bias towards the nuclear family form. We argue that practitioners need not only to expand their understanding of the risk categories for estrangement, they also need to actively support parents and grandparents in creating and maintaining wider family support networks in order to improve family resilience.     

SEIR Model to address the impact of face masks amid COVID-19 pandemic

Early in the pandemic of coronavirus disease 2019 (COVID-19), face masks were used extensively by the general public in several Asian countries. The lower transmission rate of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Asian countries compared with Western countries suggested that the wider community use of face masks has the potential to decrease transmission of SARS-CoV-2. A risk assessment model named Susceptible, Exposed, Infectious, Recovered (SEIR) model is used to quantitatively evaluate the potential impact of community face masks on SARS-CoV-2 reproduction number (R₀) and peak number of infectious persons. For a simulated population of one million, the model showed a reduction in R₀ of 49% and 50% when 60% and 80% of the population wore masks, respectively. Moreover, we present a modified model that considers the effect of mask-wearing after community vaccination. Interestingly mask-wearing still provided a considerable benefit in lowering the number of infectious individuals. The results of this research are expected to help public health officials in making prompt decisions involving resource allocation and crafting legislation.