Using the Biological Two-Stage Model to Assess Risk from Short-Term Exposures

Two assumptions used in risk assessment are investigated: (1) the assumption of fraction of lifetime dose rate assumes that the risk from a fractional lifetime exposure at a given dose rate is equal to the risk from full lifetime exposure at that same fraction of the given dose rate; (2) the assumption of fraction of lifetime risk assumes that the risk from a fractional lifetime exposure at a given dose rate is equal to that same fraction of the risk from full lifetime exposure at the same dose rate. These two assumptions are equivalent when risk is a linear function of dose. Thus both can be thought of as generalizations of the assumption that cancer risk is proportional to the total accumulated lifetime dose (or average daily dose), which is often made to assess the risk from short-term exposures. In this paper, the age-specific cumulative hazard functions are derived using the two-stage model developed by Moolgavkar, Venzon, and Knudson for situations when the exposure occurs during a single period or a single instant. The two assumptions described above are examined for three types of carcinogens, initiator, completer, and promoter, in the context of the model. For initiator and completer, these two assumptions are equivalent in the low-dose region; for a promoter, using the fraction of lifetime risk assumption is generally more conservative than that of the fraction of lifetime dose rate assumption. Tables are constructed to show that the use of either the fraction of lifetime dose rate assumption or the fraction lifetime risk assumption can both underestimate and overestimate the true risk for the three types of carcinogens.     

Explaining Intimate Partner Violence: The Sociological Limitations of Victimization Studies

This paper examines whether differentiating among types of intimate partner violence enhances the explanatory capacity of extant empirical models.The analysis uses national-level Canadian data to evaluate an alternative approach to operationalizing intimate partner violence, drawing upon Black's (1990) and Johnson's (1995) theoretical work. The main argument suggests that current efforts to explain intimate partner violence with victimization studies are inadequate because they typically do not measure key sociological variables. The failure to assess the contexts within which different types of violence occur further hinders explanatory efforts.The paper concludes with recommendations for innovative theoretical and methodological strategies to address these limitations.     

Armitage-Doll Two-Stage Model: Implications and Extension

The objective of this paper is twofold: (1) to provide insight on the simplified MVK model of carcinogenesis (a model proposed by Moolgavkar and colleagues) by revealing the relationship between the Armitage-Doll two-stage model and the simplified MVK model; and (2) to extend the Armitage-Doll two-stage model to one with time-varying (piece-wise constant) parameters. It is shown that the simplified MVK model is a special case of the Armitage-Doll two-stage model, and many applications of the simplified MVK model involving intermittent exposures or exposures to different compounds in different time periods can be derived easily from the Armitage-Doll two-stage model with piece-wise constant parameters. The limitations of the Armitage-Doll two-stage model are discussed.     

Intimate relationships and changing patterns of money management at the beginning of the twenty-first century

Drawing on British data from two annual sweeps of the ISSP eight years apart in 1994 and 2002, for modules focusing on 'Family and Changing Gender Roles', this paper examines the extent to which changes in women's labour market participation, changing ideologies/discourses of gender and changing forms of intimate relationships are affecting the ways in which couples organize household money, and the implications of such changes for recent theories of intimate relationships. The analysis indicates that by 2002, the type of relationship respondents had established, together with their social class position, were both independently related to the ways in which they managed money, after controlling for socio-economic and cultural or discursive factors. Our findings also provide a degree of support for the thesis of a partial decline in the male breadwinner model of gender, as indicated by small declines in the use of the relatively inegalitarian female whole wage and housekeeping allowance systems which were most likely to be used by married couples and cohabiting fathers, expressing relatively traditional ideologies/discourses of breadwinning - and a slight increase in the use of the partial pool, which was most likely to be used by childless cohabiting couples in which male partners expressed less traditional ideologies of breadwinning and women were in middle-class jobs with incomes high enough to facilitate partially separate finances. We also suggest, however, that in so far as cohabiting couples earning different amounts define equality as contributing equally to household expenditure, it is possible that rather than being associated with shifts to greater equality in access to money for personal spending and saving, the partial pool may be associated with marked inequalities, because it may enable gender inequalities generated in the labour market to be more directly transposed into inequalities within households, despite the decline of traditional discourses of male breadwinning and the increasing importance of egalitarian ideologies of co-provisioning.     

Inference for a Simple Step-Stress Model with Type-I Censoring and Lognormally Distributed Lifetimes

Accelerated life-testing (ALT) is a very useful technique for examining the reliability of highly reliable products. It allows the experimenter to obtain failure data more quickly at increased stress levels than under normal operating conditions. A step-stress model is one special class of ALT, and in this article we consider a simple step-stress model under the cumulative exposure model with lognormally distributed lifetimes in the presence of Type-I censoring. We then discuss inferential methods for the unknown parameters of the model by the maximum likelihood estimation method. Some numerical methods, such as the Newton–Raphson and quasi-Newton methods, are discussed for solving the corresponding non-linear likelihood equations. Next, we discuss the construction of confidence intervals for the unknown parameters based on (i) the asymptotic normality of the maximum likelihood estimators (MLEs), and (ii) parametric bootstrap resampling technique. A Monte Carlo simulation study is carried out to examine the performance of these methods of inference. Finally, a numerical example is presented in order to illustrate all the methods of inference developed here.     

Media Exposure to Terrorism and Perception of Immigrants as a Threat: The Role of Emotional Intelligence and Psychophysiological Self-Regulation

To better understand how media exposure to terrorism-related images can lead to perceiving immigrants as more threatening, in the present study we manipulated participants’ exposure to media coverage of terrorist attacks and investigated how this may influence people's perception of Arab immigrants. Considering the important role of regulatory abilities when facing stressful events like terrorist attacks, we measured individual differences in both trait emotional intelligence and resting heart rate variability (HRV). Results showed that participants perceived Arab immigrants as more threatening in the media exposure condition than in the control condition. Importantly, there were moderating effects of both trait emotional intelligence and HRV. People with lower trait emotional intelligence or lower HRV at rest felt more threatened in the media exposure condition compared to the control condition, whereas this effect was not observed among participants with higher trait emotional intelligence or higher resting HRV. The present study highlights some of the complexities related to how media exposure to terrorism-related images influences people's reactions to, and evaluations of, an outgroup that is related to the perpetrators of the attacks.     

Are dual and single exposures differently associated with clinical levels of trauma symptoms? Examining physical abuse and witnessing intimate partner violence among young children

A significant portion of children living in the United States have experienced trauma. Informed by the developmental traumatology model, we explored the effects of physical abuse and witnessing intimate partner violence (IPV) on childhood trauma symptoms. This study utilizes a convenience sample of 580 high‐risk children between 3 and 12 years who received services from one‐child advocacy centre during a 12‐month period. We performed a series of binary logistic regression analyses to examine if physical abuse, exposure to IPV, and dual exposure (i.e., both physical abuse and IPV) are distinctly associated with six trauma symptoms, including anxiety, depression, posttraumatic stress (PTS), dissociation, anger, and sexual concerns. The results indicated that dual exposure was predictive of all trauma symptoms, except for dissociation. Additionally, physical abuse was associated with PTS, anger, and sexual concerns, whereas exposure to IPV was associated with depression, PTS, and sexual concerns. Research and implications for practitioners working with young children are discussed.     

What is this moment we are caught in?

Our response to the question ‘What is this moment we are caught in?' is articulated through our collaborative reading of Berlant's (2011) Cruel Optimism (Durham, NC: Duke University Press). Cruel optimism, Berlant suggests, is a desire for something that undermines its own potentiality. As queer academics we expose the cruelty of our desires to live a good academic life, and we do so from our different positions as postdoctoral fellow, tenured academic and PhD candidate. In labouring to consolidate relationships and practices that hold the promise of our own sustainability, we give accounts of the material and affective work we perform to constitute what Berlant calls an intimate public, a collective space of mediation that functions as a key tactic to manage our academic life. These accounts take the form of three vignettes, each inflected by the specificities of our different positions and histories of becoming academics. We use Berlant as a point of departure to both interrogate practices of self‐management and find possibilities for a collective response to the moments in which we find ourselves caught.     

Understanding public perceptions of genetically modified organisms in China: The role that heuristics play during digital media exposure

This study explicates the role that heuristics play in influencing Chinese public perceptions of genetically modified organisms (GMO) when they are exposed to digital media. According to the cognitive–affective continuum of heuristics, trust in scientists and negative emotions about GMOs are a cognition-oriented heuristic and an affect heuristic, respectively. The statistical results of an online survey (N?=?414) demonstrated that trust in scientists fully mediated digital media exposure and perceptions of the risks versus benefits of GMOs. In addition, negative emotions moderated the full mediation effect, showing that the indirect effect was stronger in individuals with low levels of negative emotions than in those with high levels of negative emotions. The mediating role of trust in scientists and the moderating role of negative emotions, the two heuristics applied in this study, indicated that when negative emotions were weak, laypeople were more likely to rely on scientists to judge the consequences of GMOs than systematically process the associated information by themselves. The findings have implications for reconsidering the importance of heuristic processing in building reasonable public perceptions of risk-laden technologies through the digital environment.     

Knowledge of Suicide Risk Factors,But Not Suicide Ideation Severity,Is Greater Among College Students Who Viewed 13 Reasons Why

Abstract

Objective: To test associations between viewing 13 Reasons Why, Season 1 and past week suicide ideation severity, behavior risk, stigma, and knowledge in college students. To explore whether personal exposure to suicide and depressive symptom severity moderated these associations. Participants: Eight-hundred and eighteen college students, 64% (n?=?522) of whom watched 13 Reasons Why. Methods: Students completed surveys online. Multivariate negative binomial regressions were used to test associations between watching 13 Reasons Why and suicide-related variables, and interaction terms. Results: Suicide ideation severity and suicide behavior risk were not significantly associated with viewing 13 Reasons Why; however, there was limited statistical power to detect associations. The association between watching 13 Reasons Why and greater suicide knowledge was stronger among those who did not have personal exposure to suicide. Conclusions: 13 Reasons Why may be a platform for psychoeducation on suicide, particularly among those who do not have personal exposure.