Optimization of the Aflatoxin Monitoring Costs along the Maize Supply Chain

An optimization model was used to gain insight into cost‐effective monitoring plans for aflatoxins along the maize supply chain. The model was based on a typical Dutch maize chain, with maize grown in the Black Sea region, and transported by ship to the Netherlands for use as an ingredient in compound feed for dairy cattle. Six different scenarios, with different aflatoxin concentrations at harvest and possible aflatoxin production during transport, were used. By minimizing the costs and using parameters such as the concentration, the variance of the sampling plan, and the monitoring and replacement costs, the model optimized the control points (CPs; e.g., after harvest, before or after transport by sea ship), the number of batches sampled at the CP, and the number of samples per batch. This optimization approach led to an end‐of‐chain aflatoxin concentration below the predetermined limit. The model showed that, when postharvest aflatoxin production was not possible, it was most cost‐effective to collect samples from all batches and replace contaminated batches directly after the harvest, since the replacement costs were the lowest at the origin of the chain. When there was aflatoxin production during storage, it was most cost‐effective to collect samples and replace contaminated batches after storage and transport to avoid the duplicate before and after monitoring and replacement costs. Further along the chain a contaminated batch is detected, the more stakeholders are involved, the more expensive the replacement costs and possible recall costs become.     

On the accuracy in high‐dimensional linear models and its application to genomic selection

Genomic selection is today a hot topic in genetics. It consists in predicting breeding values of selection candidates, using the large number of genetic markers now available owing to the recent progress in molecular biology. One of the most popular methods chosen by geneticists is ridge regression. We focus on some predictive aspects of ridge regression and present theoretical results regarding the accuracy criteria, that is, the correlation between predicted value and true value. We show the influence of singular values, the regularization parameter, and the projection of the signal on the space spanned by the rows of the design matrix. Asymptotic results in a high‐dimensional framework are given; in particular, we prove that the convergence to optimal accuracy highly depends on a weighted projection of the signal on each subspace. We discuss on how to improve the prediction. Last, illustrations on simulated and real data are proposed.     

THE AGENCY OF POLITICS AND SCIENCE

We study a principal‐agent relationship between a politician and a researcher that captures stylized facts regarding the involvement of politics into scientific research. The politician has some ideal policy that he would like to implement, but needs to contract with a researcher to choose a policy that is supported by scientific advice. We study the implemented contracts under symmetric and under asymmetric information about the researcher's ability and concern for reputation, and discuss with which types of researchers the politician will contract. We identify several conflicts between the interests of voters and those of the politician. (JEL D72, D82, D83)     

Machine Learning Methods as a Tool for Predicting Risk of Illness Applying Next‐Generation Sequencing Data

Next‐generation sequencing (NGS) data present an untapped potential to improve microbial risk assessment (MRA) through increased specificity and redefinition of the hazard. Most of the MRA models do not account for differences in survivability and virulence among strains. The potential of machine learning algorithms for predicting the risk/health burden at the population level while inputting large and complex NGS data was explored with Listeria monocytogenes as a case study. Listeria data consisted of a percentage similarity matrix from genome assemblies of 38 and 207 strains of clinical and food origin, respectively. Basic Local Alignment (BLAST) was used to align the assemblies against a database of 136 virulence and stress resistance genes. The outcome variable was frequency of illness, which is the percentage of reported cases associated with each strain. These frequency data were discretized into seven ordinal outcome categories and used for supervised machine learning and model selection from five ensemble algorithms. There was no significant difference in accuracy between the models, and support vector machine with linear kernel was chosen for further inference (accuracy of 89% [95% CI: 68%, 97%]). The virulence genes FAM002725, FAM002728, FAM002729, InlF, InlJ, Inlk, IisY, IisD, IisX, IisH, IisB, lmo2026, and FAM003296 were important predictors of higher frequency of illness. InlF was uniquely truncated in the sequence type 121 strains. Most important risk predictor genes occurred at highest prevalence among strains from ready‐to‐eat, dairy, and composite foods. We foresee that the findings and approaches described offer the potential for rethinking the current approaches in MRA.     

Are they ideological renegades? Fathers' experiences on taking parental leave and gender dynamics in Korea: A qualitative study

Despite their fear of repercussions on career advancement and gender identity, Korean fathers taking parental leave have continually increased. Why do Korean fathers take parental leave in spite of the risk of being stigmatized as less masculine and less ideal workers? Are they willing to be ‘ideological renegades' to be new involved fathers? In‐depth interviews with fathers who took parental leave provide interesting answers. Overall, taking parental leave does not make fathers become ideological renegades since it is mainly utilized in a manner that accommodates the work devotion schema, deviating from the formal policy objectives. This deviant utilization is encouraged and even valued by organizations. This may be part of a psychological contract between organizations and employees, ensuring that employees are dedicated to their career even during parental leave. Furthermore, beyond the legal eligibility of uptake, informal but powerful ‘organizational eligibility' such as high performance or their contribution to the organization, makes not only the likelihood but also the aftermath of taking up different across fathers. As a result, a hierarchy among fathers with class connotations emerges. This hierarchy among fathers, combined with the traditional gender hierarchy, may reinforce the masculine fabric of ideal workers as the norm.     

Discussion on statistical analysis of carcinogenicity studies with an early terminated treated group

High rates of mortality on long term carcinogenicity studies can often result in challenges when it comes to the statistical analysis of tumor incidence. The current regulatory advice often results in treated groups being terminated earlier than the control group. However, this advice rarely considers the impact of this action on the statistical analyses. The nature of these analyses means that groups terminated at different times may not be directly comparable due to age differences of the animals. Here we discuss the issues related to this and investigate several approaches of how to incorporate these groups within the statistical analyses. Although no single method appears to resolve these issues consistently, inclusion of the early terminated group is still informative. Depending on the timing of the early termination, either pooling of the groups into a single terminal kill (TK) interval or reassignment of intervals based purely on time of death (ie, no separate TK interval) appear preferable. However, to draw meaningful conclusions the time of onset of a given tumor must also be considered alongside incident rates and any statistical findings.     

Catching a glimpse: Corona‐life and its micro‐politics in academia

The spread of COVID‐19 acutely challenges and affects not just economic markets, demographic statistics and healthcare systems, but indeed also the politics of organizing and becoming in a new everyday life of academia emerging in our homes. Through a collage of stories, snapshots, vignettes, photos and other reflections of everyday life, this collective contribution is catching a glimpse of corona‐life and its micro‐politics of multiple, often contradicting claims on practices as many of us live, work and care at home. It embodies concerns, dreams, anger, hope, numbness, passion and much more emerging amongst academics from across the world in response to the crisis. As such, this piece manifests a shared need to — together, apart — enact and explore constitutive relations of resistance, care and solidarity in these dis/organizing times of contested spaces, identities and agencies as we are living–working–caring at home during lockdowns.     

HIV/AIDS stigma manifestations during clinical interactions with MSM in Puerto Rico

HIV/AIDS stigma can have detrimental effects on physician/patient interactions when manifested by health professionals. Unfortunately, HIV/AIDS stigma is usually manifested in an intersectional manner with other preexisting stigmas, including stigma toward men who have sex with men (MSM). Therefore, our study aimed to examine the behavioral manifestations of HIV/AIDS stigma among physicians in training during simulated clinical interactions with MSM, and explore the interrelation between HIV/AIDS stigma attitudes and behaviors. We implemented an experimental design using Standardized Patient simulations with a sample of 100 physicians in training in Puerto Rico. Results show a significant difference in the two groups’ means (p?<?.001), with a higher number of stigma behaviors in the HIV MSM patient condition (M?=?6.39) than the common cold control condition (M?=?5.20). Results evidence that stigma manifestations toward MSM with HIV may continue to be an obstacle for public health in Puerto Rico, and that medical training to prevent stigma is still needed.     

Wait Until Your Mother Gets Home! Mothers' and Fathers' Discipline Strategies

From a traditional viewpoint, fathers are seen as the main disciplinarian in the family. However, recent studies suggest that these traditional family role patterns may have changed. In this study, we observed discipline strategies of mothers and fathers toward their sons and daughters. Participants included 242 families with two children (1 and 3 years of age). Findings revealed that parental discipline varied by the age of the children, but that mothers disciplined their children more often than fathers. Fathers, conversely, showed more laxness in response to child non‐compliance. Gender of the children was only related to physical interference, with mothers using more physical interference with boys than fathers, irrespective of birth order. Taken together, these findings highlight the importance of parent gender for parent–child interactions in early childhood, but also suggest that child age should be taken into account as important explanatory factors.