Modelling forces of infection by using monotone local polynomials

Summary. On the basis of serological data from prevalence studies of rubella, mumps and hepatitis A, the paper describes a flexible local maximum likelihood method for the estimation of the rate at which susceptible individuals acquire infection at different ages. In contrast with parametric models that have been used before in the literature, the local polynomial likelihood method allows this age-dependent force of infection to be modelled without making any assumptions about the parametric structure. Moreover, this method allows for simultaneous nonparametric estimation of age-specific incidence and prevalence. Unconstrained models may lead to negative estimates for the force of infection at certain ages. To overcome this problem and to guarantee maximal flexibility, the local smoother can be constrained to be monotone. It turns out that different parametric and nonparametric estimates of the force of infection can exhibit considerably different qualitative features like location and the number of maxima, emphasizing the importance of a well-chosen flexible statistical model.     

Work stress and attentional difficulties: An initial study on burnout and cognitive failures

Professional burnout is a stress-related disorder, having mental exhaustion due to work stress as its most important characteristic. Burned out individuals also often complain about attentional problems. However, it is currently not clear whether such complaints are based on true cognitive deficits or whether they merely reflect the way burned out individuals rate their own cognitive performance. To confirm the cognitive complaints we used a cognitive failure questionnaire (CFQ) to assess the level of self-reported attentional difficulties in daily life. We also measured performance on tasks of sustained attention and response inhibition (the SART and the Bourdon-Wiersma Test). We compared three groups: (1) a group of 'burned out' individuals (n=13) who stopped working due to their symptoms and sought professional treatment; (2) teachers at a vocational training institute (n=16) who reported high levels of burnout symptoms but continued to work; and (3) teachers from the same institute (n=14) who reported no burnout symptoms. The level of burnout symptoms was found to be significantly related to the number of cognitive failures in daily life, and to inhibition errors and performance variability in the attentional tasks. To our knowledge, explicit tests of objective cognitive deficits in burned out individuals have not been conducted before. Consequently, this is the first study to indicate that burnout is associated with difficulties in voluntary control over attention and that the level of such difficulties varies with the severity of burnout symptoms.     

Introduction to the Special Issue: Global Perspectives on Vocational Guidance

This special issue of The Career Development Quarterly presents the outcomes from an international symposium, titled International Perspectives on Career Development, jointly sponsored by the International Association for Educational and Vocational Guidance and the National Career Development Association. The articles in this special issue discuss international perspectives on and comparative approaches to educational and vocational guidance that differentiate career development practices in different nations. In addition to the articles in this issue, a selection of papers presented at the symposium has been jointly published in a thematic issue of the International Journal for Educational and Vocational Guidance, 5(2).     

A LIMIT OF BILATERAL CONTRACTING INSTITUTIONS

Nonconvexities undermine the efficiency of the usually robust "double auction" or DA market institution. We experimentally examine two modified DAs that allow for particularly rich bilateral contracting such as arbitrarily nonlinear pricing. The first allows for arbitrarily nonlinear pricing but should not necessarily promote it; the second should promote efficient nonlinear pricing. Experiments support predictions on the emergence of nonlinear pricing, but not those concerning efficiency. Coordination problems are the culprit. We conclude that institutions capable of dealing with some nonconvexities must frequently provide multilateral contracting possibilities not permitted by DA rules and other market-like bilateral contracting institutions. (JEL C92 , D49 , L19 )     

Living through exposure to toxic psychiatric orthodoxies: exploring narratives of people with 'mental health problems' who are looking for employment on the open labour market

This article explores lived experiences and insights of five people with long-term 'mental health problems', focusing on their search for employment in a disabling society. In our qualitative, inductive analysis we investigate why it seems almost impossible to attain a status as respected adult workers. We present five central findings: (1) losing the game before it starts; (2) internalizing the vicious circle of victim blaming; (3) from control overload to a life with inadequate supports; (4) from crushed dreams back to passive inactivity; (5) signs of resilience and resistance. In meaningful dialogue survivors give voice to alternative and plural epistemological grounds of life with 'madness'. In our concluding reflections we argue that psychiatric discourses, what we term toxic psychiatric orthodoxies, silence, disable and construct survivors as unemployable.     

The More Things Change the More They Stay the Same: Mexican Naturalization before and after Welfare Reform1

During the last decade there has been a dramatic increase in the both the number and the rate of Mexican naturalization. Some have interpreted this increase as a response to changes in welfare and immigration policy surrounding the 1996 Personal Responsibility and Work Opportunity Reconciliation Act (PRWORA), which limited public assistance to non‐citizens, and the 1996 Illegal Immigration Reform and Immigrant Responsibility Act (IIRIRA), which may have increased the incentive to naturalize by making it more difficult for legal immigrants to sponsor their relatives for entry to the United States. This article uses Current Population Survey data from 1994/95 and 2000/01 to examine how the social and economic determinants of naturalization may have changed in order to provide insight into which explanation for the increase in naturalizations is most relevant. We find that while the proportion of Mexican immigrants who are naturalized increased during the 1990s, their determinants have remained largely the same with the exception that those with noncitizen spouses have become more likely to be naturalized in the post‐reform period. This suggests that a more cautious interpretation be taken about the relationship between the increase in naturalizations and welfare and sponsorship restrictions, particularly when regarding Mexican immigrants.     

Estimating the reliability of repeatedly measured endpoints based on linear mixed‐effects models. A tutorial

There are various settings in which researchers are interested in the assessment of the correlation between repeated measurements that are taken within the same subject (i.e., reliability). For example, the same rating scale may be used to assess the symptom severity of the same patients by multiple physicians, or the same outcome may be measured repeatedly over time in the same patients. Reliability can be estimated in various ways, for example, using the classical Pearson correlation or the intra‐class correlation in clustered data. However, contemporary data often have a complex structure that goes well beyond the restrictive assumptions that are needed with the more conventional methods to estimate reliability. In the current paper, we propose a general and flexible modeling approach that allows for the derivation of reliability estimates, standard errors, and confidence intervals – appropriately taking hierarchies and covariates in the data into account. Our methodology is developed for continuous outcomes together with covariates of an arbitrary type. The methodology is illustrated in a case study, and a Web Appendix is provided which details the computations using the R package CorrMixed and the SAS software. Copyright © 2016 John Wiley & Sons, Ltd.     

Extended Analysis and Evidence Integration of Chloroprene as a Human Carcinogen

β-Chloroprene is used in the production of polychloroprene, a synthetic rubber. In 2010, Environmental Protection Agency (EPA) published the Integrated Risk Information System “Toxicological Review of Chloroprene,” concluding that chloroprene was “likely to be carcinogenic to humans.” This was based on findings from a 1998 National Toxicology Program (NTP) study showing multiple tumors within and across animal species; results from occupational epidemiological studies; a proposed mutagenic mode of action; and structural similarities with 1,3-butadiene and vinyl chloride. Using mouse data from the NTP study and assuming a mutagenic mode of action, EPA calculated an inhalation unit risk (IUR) for chloroprene of 5 × 10⁻⁴ per µg/m³. This is among the highest IURs for chemicals classified by IARC or EPA as known or probable human carcinogens and orders of magnitude higher than the IURs for carcinogens such as vinyl chloride, benzene, and 1,3-butadiene. Due to differences in pharmacokinetics, mice appear to be uniquely responsive to chloroprene exposure compared to other animals, including humans, which is consistent with the lack of evidence of carcinogenicity in robust occupational epidemiological studies. We evaluated and integrated all lines of evidence for chloroprene carcinogenicity to assess whether the 2010 EPA IUR could be scientifically substantiated. Due to clear interspecies differences in carcinogenic response to chloroprene, we applied a physiologically based pharmacokinetic model for chloroprene to calculate a species-specific internal dose (amount metabolized/gram of lung tissue) and derived an IUR that is over 100-fold lower than the 2010 EPA IUR. Therefore, we recommend that EPA's IUR be updated.     

The Job Demand-Control (-Support) Model and psychological well-being: A review of 20 years of empirical research

The Job Demand-Control (JDC) model (Karasek, 1979) and the Job Demand-Control-Support (JDCS) model (Johnson, and Hall, 1988) have dominated research on occupational stress in the last 20 years. This detailed narrative review focuses on the JDC(S) model in relation to psychological well-being. It covers research from 63 samples, published in the period 1979-1997. In the review a distinction is drawn between two different hypotheses prevailing in research on the models. According to the strain hypothesis of the JDC model, employees working in a high-strain job (high demands-low control) experience the lowest well-being. The buffer hypothesis states that control can moderate the negative effects of high demands on well-being. Translating these hypotheses to the expanded JDCS model, the iso-strain hypothesis predicts the most negative outcomes among workers in an iso-strain job (high demands-low control-low social support/isolation), whereas the buffer hypothesis states that social support can moderate the negative impact of high strain on well-being. Although the literature gives considerable support for the strain and iso-strain hypotheses, support for the moderating influence of job control and social support is less consistent. The conceptualization of demands and control is a key factor in discriminating supportive from nonsupportive studies. Only aspects of job control that correspond to the specific demands of a given job moderate the impact of high demands on well-being. Furthermore, certain subpopulations appear to be more vulnerable to high (iso)strain, whereas others benefit more from high control. On the basis of the results of this review, suggestions for future research and theoretical development are formulated.