EFFECTS OF EXPOSURE ON PREVALENCE AND CUMULATIVE RELATIVE RISK: DIRECT AND INDIRECT EFFECTS IN A RECURSIVE HAZARD MODEL

This paper outlines decomposition methods for assessing how exposure affects prevalence and cumulative relative risk. Let     x     denote a vector of exogenous covariates and suppose that a single dimension of time   t   governs two event processes     T ₁  and   T ₂.    If the occurrence of the event     T ₁    determines entry into the risk of the event     T ₂,    then subgroup variation in     T ₁    will affect the prevalence     T ₂,    even if subgroups in the population are otherwise identical. Although researchers often acknowledge this phenomenon, the literature has not provided procedures to assess the magnitude of an exposure effect of     T ₁    on the prevalence of     T ₂.    We derive decompositions that assess how variation in exposure generated by direct and indirect effects of the covariates     x     affect measures of absolute and relative prevalence of     T ₂.    We employ a parametric but highly flexible specification for baseline hazard for the     T ₁  and   T ₂    processes and use the resulting parametric proportional hazard model to illustrate the direct and indirect effects of family structure when     T ₁    is age at first sexual intercourse and     T ₂    is age at a premarital first birth for data on a cohort of non-hispanic white U.S. women.     

Bisphenol A: How the Most Relevant Exposure Sources Contribute to Total Consumer Exposure

Bisphenol A (BPA) is an endocrine disrupting chemical that is found in human urine throughout industrial societies around the globe. Consumer exposure pathways to BPA include packaged food, household dust, air, and dental fillings. To date, information on the relative contribution of the different pathways to total consumer exposure is lacking, but is key for managing substance‐associated risks. We investigated the relative contributions of the pathways known to be most relevant for nine different consumer groups. Our results suggest that the most important pathways for infants and children are the use of polycarbonate (PC) baby bottles and for adults and teenagers the consumption of canned food. Dental surgery can also considerably contribute over a short time directly after the surgery. For infants fed with PC baby bottles with mean dose rates of 0.8 μg/kg_bw/d the highest exposure dose rate was calculated. This dose rate is far below the tolerable daily intake of 50 μg/kg_bw/d. However, it is of the same order of magnitude as recently reported concentrations that caused low‐dose health effects in rodents. We find a pattern of falling exposure levels with rising age that is supported by urinary concentrations of BPA available for selected consumer groups. Similarly, the exposure levels we predict are confirmed by the levels reported in these studies.     

“A stone wall out of the earth that thundering cannon cannot destroy"? Bastion and Moat at the Castle,Cape Town

Although the urgency with which the Dutch East India Company administration at the Cape built defensive works was a direct result of their fear of attack from both land and sea, there was an additional imperative, for the Castle at Cape Town stood as a symbol of Dutch colonial aspirations. In this paper, we compare written and material texts of one part of the Castle's architecture to show firstly, how the discordances between such sources can reveal an underside of early colonization and secondly, how the Castle moat, in the seventeenth century a stamp of aspirant power, was by the mid‐nineteenth century a dump and a public nuisance.     

Innovativeness and Subjective Well-Being

What are the effects of innovativeness on well-being? This paper argues that research on subjective well-being has progressed to a point where measures of subjective well-being (or: happiness) can usefully be employed to assess the welfare effects of innovative change. Based on a discussion of the prospects and pitfalls associated with subjective well-being as welfare measure and benchmark of societal progress, an argument is put forward as to why these measures are particularly well-suited in the context of innovative change. Empirically well-founded and with an explicit dynamic foundation, theories of subjective well-being allow for a nuanced and comprehensive assessment of the effects that innovativeness has on a society. Two evaluation rules, the “life domain evaluation principle” and the “welfare dynamics principle” are suggested to guide such normative assessment.     

A hybrid genetic algorithm/mathematical programming approach to the multi-family flowshop scheduling problem with lot streaming

This paper presents a hybrid genetic algorithm/mathematical programming heuristic for the n-job, m-machine flowshop problems with lot streaming. The number of sublots for each job and the size of sublots are directly addressed by the heuristic and setups may be sequence-dependent. A new aspect of the problem, the interleaving of sublots from different jobs in the processing sequence, is developed and addressed. Computational results from 12 randomly generated test sets of 24 problems each are presented.     

Alternative Methods for Computing the Sensitivity of Complex Surveillance Systems

Stochastic scenario trees are a new and popular method by which surveillance systems can be analyzed to demonstrate freedom from pests and disease. For multiple component systems—such as a combination of a serological survey and systematically collected observations—it can be difficult to represent the complete system in a tree because many branches are required to represent complex conditional relationships. Here we show that many of the branches of some scenario trees have identical outcomes and are therefore redundant. We demonstrate how to prune branches and derive compact representations of scenario trees using matrix algebra and Bayesian belief networks. The Bayesian network representation is particularly useful for calculation and exposition. It therefore provides a firm basis for arguing disease freedom in international forums.     

Television and Postfeminist Housekeeping: No Time for Mother

This feminist, qualitative study sheds light on how young Arab women used cyberactivism to participate in the wave of political and social transformations widely known as the Arab Spring. It argues that these activists leveraged social media to enact new forms of leadership, agency, and empowerment, since these online platforms enabled them to express themselves freely and their voices to be heard by the rest of the world, particularly the global media. This resulted in a multidimensional personal, social, political, and communicative revolution. This study is based on in-depth, personal interviews with more than twenty young Arab women citizen journalists, bloggers, and activists from Arab countries that witnessed political upheaval.