The increase in marital status differences in mortality up to the oldest age in seven European countries, 1990–99

We investigate mortality differentials by marital status among older age groups using a database of mortality rates by marital status at ages 40 and over for seven European countries with 1 billion person-years of exposure. The mortality advantage of married people, both men and women, continues to increase up to at least the age group 85–89, the oldest group we are able to consider. We find the largest absolute differences in mortality levels between marital status groups are at high ages, and that absolute differentials are: (i) greater for men than for women; (ii) similar in magnitude across countries; (iii) increase steadily with age; and (iv) are greatest at older age. We also find that the advantage enjoyed by married people increased over the 1990s in almost all cases. We note that results for groups such as older divorced women need to be interpreted with caution.     

Evaluation of the benchmark dose for point of departure determination for a variety of chemical classes in applied regulatory settings

Repeated-dose studies received by the New Substances Assessment and Control Bureau (NSACB) of Health Canada are used to provide hazard information toward risk calculation. These studies provide a point of departure (POD), traditionally the NOAEL or LOAEL, which is used to extrapolate the quantity of substance above which adverse effects can be expected in humans. This project explored the use of benchmark dose (BMD) modeling as an alternative to this approach for studies with few dose groups. Continuous data from oral repeated-dose studies for chemicals previously assessed by NSACB were reanalyzed using U.S. EPA benchmark dose software (BMDS) to determine the BMD and BMD 95% lower confidence limit (BMDL(05) ) for each endpoint critical to NOAEL or LOAEL determination for each chemical. Endpoint-specific benchmark dose-response levels , indicative of adversity, were consistently applied. An overall BMD and BMDL(05) were calculated for each chemical using the geometric mean. The POD obtained from benchmark analysis was then compared with the traditional toxicity thresholds originally used for risk assessment. The BMD and BMDL(05) generally were higher than the NOAEL, but lower than the LOAEL. BMDL(05) was generally constant at 57% of the BMD. Benchmark provided a clear advantage in health risk assessment when a LOAEL was the only POD identified, or when dose groups were widely distributed. Although the benchmark method cannot always be applied, in the selected studies with few dose groups it provided a more accurate estimate of the real no-adverse-effect level of a substance.     

Reciprocity in relationships: socio-economic and health influences on intergenerational exchanges between Third Age parents and their adult children in Great Britain

In this paper data from a nationally representative British longitudinal study are used to analyse exchanges of support between Third Age parents (aged 55-75) and their adult children. Results show that between two thirds and three quarters of parents in this age group were involved in some sort of exchange relationship with at least one of their children. Generally, more Third Age parents were providers than recipients of help, but there was a strong reciprocal element to intergenerational exchange with, for example, married parents who provided support to at least one child being twice as likely as those who did not to receive support from a child, after allowance for a range of relevant parental and child characteristics. Parental characteristics associated with higher probability of providing help included higher income, home ownership and being married or widowed rather than divorced. Higher income and home ownership were, however, negatively associated with odds of receiving help from a child, again after adjustment for other co-variates, suggesting socio-economic differences in the balance of support exchanges. Children seem responsive to parental needs in that receipt of help from a child was positively associated with older parental age and with parental disability. The paper shows that in Britain, as in the USA, the balance of intergenerational exchanges involving Third Age adults is downward rather than upward, in contravention of depictions of older adults as 'burdens' on younger generations. Current demographic and social changes are, it is argued, likely to increase support demands from adult children to Third Age parents in coming decades.     

A methodological approach to strategic petroleum reserves

Energy constitutes a small fraction of the production inputs in the economy, yet the rigidity imposed by the short and medium term inability to substitute energy with other production factors in case of an energy shortage, requires the establishment of safeguard mechanisms to ensure sufficient energy supply during an emergency. These safeguards usually take the form of strategic energy reserves. A methodological approach is presented here, relating the level of strategic petroleum reserves, the decision variable, with the costs associated with their storage and the economic losses incurred by an energy shortage. This approach is based on the use of a decision tree, to portray emergency scenarios. Each scenario, a branch of the decision tree, can be evaluated in terms of a cost function which includes the inventory procurement and maintenance cost and the shortage cost inflicted by a petroleum shortfall.     

Fertility trajectories and later-life depression among parents in England

We examine pathways between indicators of fertility tempo/quantum and depressive symptoms among parents aged 55+ with at least two children, using three waves of the English Longitudinal Study of Ageing. Using standard regression approaches and path analysis within the structural equation framework, we also investigate whether fertility trajectories mediated the association between childhood disadvantage and later-life depression. Results provide limited support for direct influences of fertility trajectories on depression, but indicate indirect linkages for both women and men. Associations are mediated by partnership history, social support, wealth, later-life smoking, and functional limitation. Associations between childhood disadvantage and later-life depression are partially mediated by fertility stressors. Results confirm the influence of life course experiences on depression at older ages and demonstrate the interlinked role of family and other life course pathways on later-life well-being.     

Route first—Cluster second methods for vehicle routing

In this paper we consider route first—cluster second methods for the vehicle routing problem. Extensions to the basic method both to improve its effectiveness and to enable it to cope with practical constraints are described. Computational results are given for the method applied to standard vehicle routing problems drawn from the literature.     

Fertility history, health, and health changes in later life: a panel study of British women and men born 1923-49

We investigated associations between later-life health and fertility history for women and men, using the British Household Panel Survey. We modelled health and its rate of change jointly with sample retention over an 11-year period. For women, childlessness is associated with limitation of activity for health reasons and faster acquisition of the limitation. High parity (four or more children) is associated with poorer health for both women and men. For the parous, this association is also found when age at first birth is controlled. Early parenthood is associated with poorer health. For parents of two or more children, a birth interval of less than 18 months is associated with having a health limitation and an accelerated rate of acquiring it. We conclude that biosocial pathways link parenthood careers and the later-life health of both women and men, and that implications of closely spaced births for parents merit further attention.