New Data,Strategies, and Insights for Listeria monocytogenes Dose‐Response Models: Summary of an Interagency Workshop, 2011

Listeria monocytogenes is a leading cause of hospitalization, fetal loss, and death due to foodborne illnesses in the United States. A quantitative assessment of the relative risk of listeriosis associated with the consumption of 23 selected categories of ready‐to‐eat foods, published by the U.S. Department of Health and Human Services and the U.S. Department of Agriculture in 2003, has been instrumental in identifying the food products and practices that pose the greatest listeriosis risk and has guided the evaluation of potential intervention strategies. Dose‐response models, which quantify the relationship between an exposure dose and the probability of adverse health outcomes, were essential components of the risk assessment. However, because of data gaps and limitations in the available data and modeling approaches, considerable uncertainty existed. Since publication of the risk assessment, new data have become available for modeling L. monocytogenes dose‐response. At the same time, recent advances in the understanding of L. monocytogenes pathophysiology and strain diversity have warranted a critical reevaluation of the published dose‐response models. To discuss strategies for modeling L. monocytogenes dose‐response, the Interagency Risk Assessment Consortium (IRAC) and the Joint Institute for Food Safety and Applied Nutrition (JIFSAN) held a scientific workshop in 2011 (details available at http://foodrisk.org/irac/events/ ). The main findings of the workshop and the most current and relevant data identified during the workshop are summarized and presented in the context of L. monocytogenes dose‐response. This article also discusses new insights on dose‐response modeling for L. monocytogenes and research opportunities to meet future needs.     

美国视频通信市场的转型——付费视频内容转向互联网

本文概述了当前美国有线电视行业／付费视频行业的局势，以及一些重要问题和面临的挑战，展望了未来的视频市场，概述了一个未来视频／宽带市场的战略愿景，然后回归到政策建议及具体的立法和管制行动。这将帮助我们在最短的、可操作的时间内通向一个开放的、非歧视性的、无处不在的宽带网络。     

The distinct role of group-central and group-peripheral norms in taxpaying behaviour

In recent years, a social identity approach has been used to help understand why people do or do not pay tax [see Taylor, 2003; Wenzel, M., 2002. The impact of outcome orientation and justice concerns on tax compliance: the role of taxpayers’ identity. Journal of Applied Psychology 87, 629–645; Wenzel, M., 2004. An analysis of norm processes in tax compliance. Journal of Economic Psychology 25, 213–228; Wenzel, M., 2005. Misperception of social norms about tax compliance: from theory to intervention. Journal of Economic Psychology 26, 862–883; Wenzel, M., 2007. The multiplicity of taxpayer identities and their implications for tax ethics. Law & Policy 29, 31–50]. This research, which has focused almost exclusively on national identity, indicates that the more people identify with a group, the more likely they are to adhere to its tax norms and values. However, conformity to group norms may be more nuanced than this, and depend on (a) the meaning or content of the identity in question [e.g., Turner, J.C., 1999. Some current themes in research on social identity and self-categorization theories. In: Ellemers, N., Spears, R., Doojse, B. (Eds.), Social Identity: Context, Commitment, Content. Blackwell, Oxford, pp. 6–34] and (b) whether the norms and values are central or peripheral to the content of that identity. In line with this idea, two studies explored whether the concept and act of taxpaying are more central to what it means to be a member of one's nation than of one's occupational group. Both studies confirm this expectation. Importantly, the findings also suggest that although occupational groups have different norms and values in relation to pre-tax behaviours (e.g., how to deal with extra income), these too can be peripheral to what it means to a group member. If norms are peripheral to identity content, conformity to such norms may be independent of group identification.     

The trend of intelligence in certain districts of England

An estimate of the change in intelligence in ten English education authorities during the past 10 years has been made by comparing the scores of complete year groups of 11-year-old children in 1947 with scores made by similar groups in the same test on an earlier occasion. The first test was taken by 31,728 children and the second by 28,505 children, boys and girls in approximately equal numbers.

For boys and girls together there was a fall of 0.0034 point of intelligence quotient per year, which was far from significant. In seven districts where we had separate scores for boys and girls on both occasions there was a significant fall in intelligence quotient of 0.0921 point per year amongst boys and a significant rise of 0.0921 point per year amongst girls.

The adventitious influences which might invalidate a comparison of the two sets of scores have been considered; they probably tend to depress the score at the second test.

A study of sex differences in attainment tests at 11 years and in intelligence tests at 13 years and later suggests that the scores of the boys in 1947 are underestimates of their ability, and that a truer measure of the trend of intelligence amongst the population is represented by the change in the girls' scores.

By assuming a certain parallelism between the present survey and that of the Scottish children, the rise in intelligence quotient of the latter is estimated at 0.0543 point per year.

A significant increase in the dispersion of intelligence test score of both boys and girls during the past 10 years has been recorded.     

Pre‐procreative ages in population stability and cyclicity

Age‐specific models of population renewal (with and without feedback) which imply convergence to a stable state for some levels of fertility or feedback may imply the presence of long‐term cycling around a constant or exponentially changing equilibrium for other levels of fertility or feedback. The switch from one regime to the other is a “bifurcation.”; The conditions for bifurcation involve the roots of an analogue of Lotka's Equation.

Typically bifurcation is induced by raising the strength of feedback or the level of fertility. It has been known since the early 1980s, however, that this is sometimes impossible. It is sometimes impossible even with the linear renewal equation itself and with the most basic of non‐linear models, Lee's cohort feedback model.

Here it is proved that this typical route to bifurcation does not fail for these basic models in the presence of a condition which always holds for realistic applications with higher organisms: the existence of a span of ages before the onset of fertility.

Specifically, a strictly positive lower bound on ages of procreation is proved to be sufficient to guarantee the existence of a rescaling of Lotka's Equation for which the real part of some complex root vanishes. This result holds for absolutely Lebesgue‐integrable (signed) net maternity functions on the positive real line and for absolutely summable (signed) net maternities on the positive integers.

It follows that Coale's rescaling device for the analysis of approach to stability in stable population theory can be implemented for all realistic human net maternity schedules. It also follows that the many special cases of the cohort feedback model throughout population biology will all generate persistent cycling instead of stability if feedback is sufficiently strong.     

The estimation of fertility rates from ratios of total to first births

In a previous paper a formula was derived from which the total fertility rate of a group of women could be estimated from the average number of live births to women in the reproductive period. In the present paper the argument is carried further and a method is given by which the total fertility rate may be estimated from the average number of children born to fertile women during the reproductive period. The method given in this paper may, under certain circumstances, have considerable advantages over the previous method suggested.     

Pre-term Foetal Life Times in Scotland

A proportional hazards model was used to evaluate the association between ten categorical covariates and the risk of pre-term delivery for women having their first child and women in subsequent pregnancies. An adaptation of the model for use with grouped survival times made it possible to model foetal life times between 28 and 36 completed weeks of gestation for 67,000 Scottish singleton births in 1981. The use of the model was justified by testing time-dependent effects. For both groups of women age, and a history of abortion, were major factors associated with increased hazard. For women experiencing a second or higher-order birth a history of perinatal death was also associated with substantially increased hazard to the pregnancy.     

Application of load-oriented manufacturing control in industry

This paper deals with multi-stage lotsizing models for imperfect production processes. The effect of imperfect quality on lotsizing decisions and effect ofinspection errorsare taken into consideration in the proposed models. Numerical examples are presented for illustration purposes. The developed models are very helpful for justifying quality assurance and quality improvement efforts.     

On the α-risks for shewhart control charts

The performance of the usual Shewhart control charts for monitoring process means and variation can be greatly affected by nonnormal data or subgroups that are correlated. Define the α_k-risk for a Shewhart chart to be the probability that at least one “out-of-control” subgroup occurs in k subgroups when the control limits are calculated from the k subgroups. Simulation results show that the α_k-risks can be quite large even for a process with normally distributed, independent subgroups. When the data are nonnormal, it is shown that the α_k-risk increases dramatically. A method is also developed for simulating an “in-control” process with correlated subgroups from an autoregressive model. Simulations with this model indicate marked changes in the α_k-risks for the Shewhart charts utilizing this type of correlated process data. Therefore, in practice a process should be investigated thoroughly regarding whether or not it is generating normal, independent data before out-of-control points on the control charts are interpreted to be due to some real assignable cause.