Risk-Based Analysis of the Danish Pork Salmonella Program: Past and Future

The Danish pork Salmonella control program was initiated in 1993 in response to a prominent pork-related outbreak in Copenhagen. It involved improved efforts at slaughter hygiene (postharvest) and on-farm (preharvest) surveillance and control. After 10 years, 95 million Euros, significant reductions in seropositive herds, Salmonella positive carcasses, and pork-attributable human cases (PAHC), questions have arisen about how best to continue this program. The objective of this study was to provide some analysis and information to address these questions. The methods used include a computer simulation model constructed of a series of Excel workbooks, one for each simulated year and scenario ( http://www.ifss.iastate/DanSalmRisk ). Each workbook has three modules representing the key processes affecting risk: seropositive pigs leaving the farm (Production), carcass contamination after slaughter (Slaughter), and PAHC of Salmonella (Attribution). Parameter estimates are derived from an extensive farm-to-fork database collected by industry and government and managed by the Danish Zoonosis Centre ( http://www.food.dtu.dk ). Retrospective (1994–2003) and prospective (2004–2013) simulations were evaluated. The retrospective simulations showed that, except for the first few years (1994–1998), the on-farm program had minimal impact in reducing the number of positive carcasses and PAHC. Most of the reductions in PAHC up to 2003 were, according to this analysis, due to various improvements in abattoir processes. Prospective simulations showed that minimal reductions in human health risk (PAHC) could be achieved with on-farm programs alone. Carcass decontamination was shown as the most effective means of reducing human risk, reducing PAHC to about 10% of the simulated 2004 level.     

Prevalence and correlates of problematic gambling among Danish adolescents

This study reports the findings from a national survey on gambling behaviour among Danish primary school children. A questionnaire was administered to 2,223 primary school students ranging in age from 11 to 17 years. The questionnaire contained a gambling screen (SOGS‐RA) and items that measure gambling behaviour, social network and cognitive perceptions. The prevalence of problem gambling was 1.29 per cent, while 4.5 per cent were categorised as at‐risk gamblers. The three most frequently reported reasons for gambling were to win money, to have fun and to socialise with family and friends. It is suggested that gambling may be linked to a masculine universe and that at‐risk gambling behaviour patterns may be part of a normal adolescent life in which gambling serves recreational or leisure purposes. Implications for further research and preventive measures are discussed.     

Broadening the Study of Infant Security of Attachment: Maternal Autonomy‐support in the Context of Infant Exploration

Although security of attachment is conceptualised as a balance between infants' attachment and exploratory behaviours, parental behaviours pertaining to infant exploration have received relatively little empirical attention. Drawing from self‐determination theory, this study seeks to improve the prediction of infant attachment by assessing maternal autonomy‐support during infant exploration, in addition to maternal sensitivity. Seventy‐one dyads participated in two home visits. Maternal sensitivity was assessed when the infants were 12 months old, whereas maternal autonomy‐support and infant attachment were assessed at 15 months. The results revealed that autonomy‐support explained an additional portion of the variance in attachment when maternal socioeconomic status and sensitivity were controlled. These results speak to the relevance of a theory‐driven approach to examining maternal behaviours in the context of child exploration.     

The Within‐Job Motherhood Wage Penalty in Norway, 1979–1996

The motherhood wage penalty is a substantial obstacle to progress in gender equality at work. Using matched employer–employee data from Norway (1979–1996, N = 236,857 individuals, N = 1,027,462 individual‐years), a country with public policies that promote combining family and career, we investigate (a) whether the penalty arises from differential pay by employers or from the sorting of employees on occupations and establishments and (b) changes in the penalties during a period with major changes in family policies. We find that (a) the penalty to motherhood was mostly due to sorting on occupations and occupation‐establishment units (mothers and nonmothers working in the same occupation and establishment received similar pay), and (b) the wage penalties to motherhood declined substantially over the 18‐year period.     

Estimating and Testing Nonlinear Local Dependence Between Two Time Series

ABSTRACT

The most common measure of dependence between two time series is the cross-correlation function. This measure gives a complete characterization of dependence for two linear and jointly Gaussian time series, but it often fails for nonlinear and non-Gaussian time series models, such as the ARCH-type models used in finance. The cross-correlation function is a global measure of dependence. In this article, we apply to bivariate time series the nonlinear local measure of dependence called local Gaussian correlation. It generally works well also for nonlinear models, and it can distinguish between positive and negative local dependence. We construct confidence intervals for the local Gaussian correlation and develop a test based on this measure of dependence. Asymptotic properties are derived for the parameter estimates, for the test functional and for a block bootstrap procedure. For both simulated and financial index data, we construct confidence intervals and we compare the proposed test with one based on the ordinary correlation and with one based on the Brownian distance correlation. Financial indexes are examined over a long time period and their local joint behavior, including tail behavior, is analyzed prior to, during and after the financial crisis. Supplementary material for this article is available online.     

A Class of Markov Chain Models for Average Run Length Computations for Autocorrelated Processes

The average run length (ARL) of conventional control charts is typically computed assuming temporal independence. However, this assumption is frequently violated in practical applications. Alternative ARL computations have often been conducted via time consuming and yet not necessarily very accurate simulations. In this article, we develop a class of Markov chain models for evaluating the run length performance of traditional control charts for autocorrelated processes. We show extensions from the univariate AR(1) model to the general multivariate VARMA(p, q) time series. The results of the proposed method are highly comparable to those of simulations and with significantly less computational overhead.     

The reform of the welfare services in Norway: one office – one way of thinking?

This paper discusses the professional role of social workers in the new Norwegian Nav system. The Nav reform merged the state social insurance office, the state employment office and components of municipal social services. The aim is to include clients in the work force by making the services more holistic and efficient. The paper presents a discussion of the introduction of the ‘Nav reform’, drawing on a qualitative multi-method study. The material sheds light on a social worker's role under pressure to work in a more standardised and ‘simplified’ way. Social workers at the Nav offices must adjust to expectations that require a general, basic and common competence for all employees, as one type of comprehensive, but simplified and non-specialised, approach. The study describes the dilemma of how to combine one-stop service and specialist principles. The paper attempts to criticise ‘the flexible system’ related to Whole of Government perspectives and one-stop service principles as a generalist ‘light’ approach, as opposed to the generalist approach in social work. The findings provide a basis for raising questions about the development of the social worker's role in light of the post-New Public Management (NPM) reforms and the potential threat to the professional basis of social work.     

A stochastic model for change in group structure

This paper develops and tests a continuous time discrete state Markov Chain as a model for change in group structure. Movement of triads among different states is focused upon. It is shown formally that a triad cannot move to a state where all the pair relationships are mutual without incurring intransitivity. An empirical test on the change in sociometric structures provides support for the model.     

Can Balance be Boring? A Critique of the “Challenges Should Match Skills” Hypotheses in Flow Theory

Two separate studies investigated if the balance between challenges and skills is the best indicator of a subjective experience in general and of an optimal experience in particular. Study 1 followed a group of 64 first year sport- and outdoor students on a 3 day coastal trip and a 3 day ski trip (10 event measures) and their memory of their trip (4 remembered measures), which gave 698 single reports on subjective experiences (76%). Study 2 followed a group of 26 s year outdoor students on a 5 day glacier course (10 event measures), which gave 260 single reports (100%). Multiple regression analysis, all with challenges, skills and the interaction between challenges and skills as the independent variables gave no support to the challenge skill ratio on subjective experiences, explaining on average 9 and 14 % of a scope of positive and negative experiences in Study 1 and Study 2 respectively. In Study 1, the experience fluctuation model (EFM) explained 2 % of the variance in a variable measuring pleasure and 3 % of the variance in an interest variable. In study 2, the EFM explained 12.7 % of the variance in the pleasure variable and 10.8 % of the variance in the interest variable. Neither of our flow indicators peaked in the balance condition of challenges and skills. Rather, empirical support was given for an imbalance model of challenges and skills. The findings contest the widespread idea that flow is produced when challenges and skills are harmonized.