The Emergence of Reactive Strategies in Simulated Heterogeneous Populations

The computer simulation study explores the impact of the duration of social impact on the generation and stabilization of cooperative strategies. Rather than seeding the simulations with a finite set of strategies, a continuous distribution of strategies is being defined. Members of heterogeneous populations were characterized by a pair of probabilistic reactive strategies: the probability to respond to cooperation by cooperation and the probability to respond to defection by cooperation. This generalized reactive strategy yields the standard TFT mechanism, the All-Cooperate, All-Defect and Bully strategies as special cases. Pairs of strategies interacted through a Prisoner's Dilemma game and exerted social influence on all other members. Manipulating: (i) the initial distribution of populations' strategies, and (ii) the duration of social influence, we monitored the conditions leading to the emergence and stabilization of cooperative strategies. Results show that: (1) The duration of interactions between pairs of strategies constitutes a crucial factor for the emergence and stabilization of cooperative strategies, (2) Unless sufficient learning intervals are provided, initializing the simulations with cooperative populations does not guarantee that cooperation will sustain.     

Staying Connected: An Examination of Relationship Maintenance Behaviors in Long-Distance Relationships

Romantic long-distance relationships (LDRs) are becoming increasingly prevalent as individuals seek educational and employment opportunities across the globe. LDRs create unique challenges for couples, potentially impacting couple and individual well-being. It is important to understand efforts that LDR partners make to stay engaged, known as relationship maintenance behaviors (RMBs), and whether common RMBs facilitate or hinder relational and individual functioning. This study has two goals: (a) to examine whether RMBs predict relationship satisfaction and (b) to investigate whether relationship satisfaction mediates the association between RMBs and individual functioning. Eighty-seven adults in LDRs participated in our online survey. Results indicated that RMBs predicted relationship satisfaction, some negatively, and that relationship satisfaction was a mediator between RMBs and individual well-being.     

How do social work novices and experts solve professional problems? A micro-analysis of epistemic activities and the use of evidence

Evidence-based practice in social work is an intensely debated topic, with many differing perspectives on how it should be done. However, we know surprisingly little about how social workers actually engage in professional problem-solving and about the knowledge base of those processes. To shed light on this topic of social work expertise, we present a novel model of scientific reasoning and argumentation and investigate how experts and novices differ in the reasoning processes they engage in as they are confronted with social work problems. Vignettes were used to capture reasoning processes, and the corresponding verbal data were then analysed. In this study, 26 probation officers and 22 social work students participated. The findings show that experts differ from novices with respect to both their knowledge bases and the epistemic activities in which they engage. Furthermore, a cluster analysis revealed three common problem-solving strategies: evidence-based solution seeking (15 experts and 15 novices), shared problem-solving (8 experts) and explanation seeking (1 expert and 7 novices). The results indicate the need to improve the practical problem-solving skills of students through situated teaching methods.     

A prospective study of sexual assault and alcohol use among first-year college women

This study prospectively examined the relation between alcohol use and sexual assault in a sample (N = 319) of first-year college women. Both frequency of drinking and frequency of binge drinking were measured. Over the course of their freshman year, 19.3% reported experiencing at least one sexual assault. Frequent binge drinking and frequent drinking predicted a subsequent sexual assault; however, experiencing a sexual assault did not predict changes in alcohol use. Frequent binge drinking demonstrated a stronger association with sexual assault than did frequent drinking. Findings help clarify the relation between alcohol use and sexual assault in college women and call for continued differentiation in assessment of alcohol use.     

Consumer Responses to Integrated Risk‐Benefit Information Associated with the Consumption of Food

The risk analysis of the health impact of foods is increasingly focused on integrated risk‐benefit assessment, which will also need to be communicated to consumers. It therefore becomes important to understand how consumers respond to integrated risk‐benefit information. Quality‐adjusted‐life‐years (QALYs) is one measure that can be used to assess the balance between risks and benefits associated with a particular food. The effectiveness of QALYs for communicating both positive and negative health effects associated with food consumption to consumers was examined, using a 3 × 2 experiment varying information about health changes in terms of QALYs associated with the consumption of fish (n = 325). The effect of this information on consumer perceptions of the usefulness of QALYs for describing health effects, on risk and benefit perceptions, attitudes, and intentions to consume fish was examined. Results demonstrated that consumers perceived QALYs as useful for communicating health effects associated with food consumption. QALYs communicated as a net effect were preferred for food products associated with negative net effects on health, while separate communication of both risks and benefits may be preferred for food products associated with positive or zero net health effects. Information about health changes in terms of QALYs facilitated informed decision making by consumers, as indicated by the impact on risk and benefit perceptions as intended by the information. The impact of this information on actual food consumption choices merits further investigation.     

Food Safety in the Domestic Environment: The Effect of Consumer Risk Information on Human Disease Risks

The improvement of food safety in the domestic environment requires a transdisciplinary approach, involving interaction between both the social and natural sciences. This approach is applied in a study on risks associated with Campylobacter on broiler meat. First, some web-based information interventions were designed and tested on participant motivation and intentions to cook more safely. Based on these self-reported measures, the intervention supported by the emotion "disgust" was selected as the most promising information intervention. Its effect on microbial cross-contamination was tested by recruiting a set of participants who prepared a salad with chicken breast fillet carrying a known amount of tracer bacteria. The amount of tracer that could be recovered from the salad revealed the transfer and survival of Campylobacter and was used as a measure of hygiene. This was introduced into an existing risk model on Campylobacter in the Netherlands to assess the effect of the information intervention both at the level of exposure and the level of human disease risk. We showed that the information intervention supported by the emotion "disgust" alone had no measurable effect on the health risk. However, when a behavioral cue was embedded within the instruction for the salad preparation, the risk decreased sharply. It is shown that a transdisciplinary approach, involving research on risk perception, microbiology, and risk assessment, is successful in evaluating the efficacy of an information intervention in terms of human health risks. The approach offers a novel tool for science-based risk management in the area of food safety.     

A Tail Quantile Approximation for the Student t Distribution

In this article, we derive a new formula for extreme Student t quantiles. We use the fact that the Student t distribution arises as the limit of a variance-mixture of normals. For the normal distribution there is already a tail quantile formula derived by Reiss (1989 Reiss , R.-D. ( 1989 ). Approximate Distributions of Order Statistics: With Applications to Non-parametric Statistics . New York : Springer .[Crossref] , [Google Scholar]). We generalize his procedure and transfer it to our scenario.

Eventually, we compare the quantile estimates of our formula to those from Gafer and Kafadar (1984 Gafer , D. P. , Kafadar , K. ( 1984 ). A retrievable recipe for inverse t. Amer. Statistician 38(4):308–311 . [Google Scholar]), who also derived a Student t quantile formula. Using R to generate a benchmark we find that our method is more accurate for very high quantiles.     

Structure-preserving mappings of uniform order statistics

There are several well-known mappings which transform the first r common order statistics in a sample of size n from a standard uniform distribution to a full vector of dimension r of order statistics in a sample of size r from a uniform distribution. Continuing the results reported in a previous paper by the authors, it is shown that transformations of these types do not lead to order statistics from an i.i.d. sample of random variables, in general, when being applied to order statistics from non-uniform distributions. By accepting the loss of one dimension, a structure-preserving transformation exists for power function distributions.