Exposure Reconstruction for the TCDD-Exposed NIOSH Cohort Using a Concentration- and Age-Dependent Model of Elimination

Recent studies demonstrating a concentration dependence of elimination of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) suggest that previous estimates of exposure for occupationally exposed cohorts may have underestimated actual exposure, resulting in a potential overestimate of the carcinogenic potency of TCDD in humans based on the mortality data for these cohorts. Using a database on U.S. chemical manufacturing workers potentially exposed to TCDD compiled by the National Institute for Occupational Safety and Health (NIOSH), we evaluated the impact of using a concentration- and age-dependent elimination model (CADM) (Aylward et al., 2005) on estimates of serum lipid area under the curve (AUC) for the NIOSH cohort. These data were used previously by Steenland et al. (2001) in combination with a first-order elimination model with an 8.7-year half-life to estimate cumulative serum lipid concentration (equivalent to AUC) for these workers for use in cancer dose-response assessment. Serum lipid TCDD measurements taken in 1988 for a subset of the cohort were combined with the NIOSH job exposure matrix and work histories to estimate dose rates per unit of exposure score. We evaluated the effect of choices in regression model (regression on untransformed vs. ln-transformed data and inclusion of a nonzero regression intercept) as well as the impact of choices of elimination models and parameters on estimated AUCs for the cohort. Central estimates for dose rate parameters derived from the serum-sampled subcohort were applied with the elimination models to time-specific exposure scores for the entire cohort to generate AUC estimates for all cohort members. Use of the CADM resulted in improved model fits to the serum sampling data compared to the first-order models. Dose rates varied by a factor of 50 among different combinations of elimination model, parameter sets, and regression models. Use of a CADM results in increases of up to five-fold in AUC estimates for the more highly exposed members of the cohort compared to estimates obtained using the first-order model with 8.7-year half-life. This degree of variation in the AUC estimates for this cohort would affect substantially the cancer potency estimates derived from the mortality data from this cohort. Such variability and uncertainty in the reconstructed serum lipid AUC estimates for this cohort, depending on elimination model, parameter set, and regression model, have not been described previously and are critical components in evaluating the dose-response data from the occupationally exposed populations.     

Uncovering the Mystery of How Users Find and Use eBooks through Guerilla Usability Testing

Abstract

This case study focuses on user research that was conducted to enhance our users’ ebook discovery experience. We took an outward-facing approach by seeking the users’ perspectives. We wanted to know: How do users find ebooks? How do they perceive multiple records for the same title? Would users find additional metadata useful, such as download availability, file format, and chapter titles? We coordinated guerilla usability testing in our library lobby, inspired by low-overhead, high-impact user experience work at other academic libraries. The resulting data gave us a much-needed new perspective of ebook usage that supplements what we already know from our day-to-day work.     

Simultaneous model-based clustering and visualization in the Fisher discriminative subspace

Clustering in high-dimensional spaces is nowadays a recurrent problem in many scientific domains but remains a difficult task from both the clustering accuracy and the result understanding points of view. This paper presents a discriminative latent mixture (DLM) model which fits the data in a latent orthonormal discriminative subspace with an intrinsic dimension lower than the dimension of the original space. By constraining model parameters within and between groups, a family of 12 parsimonious DLM models is exhibited which allows to fit onto various situations. An estimation algorithm, called the Fisher-EM algorithm, is also proposed for estimating both the mixture parameters and the discriminative subspace. Experiments on simulated and real datasets highlight the good performance of the proposed approach as compared to existing clustering methods while providing a useful representation of the clustered data. The method is as well applied to the clustering of mass spectrometry data.     

Illuminating the Phenomenological Challenges of Cross-Cultural Supervision

ABSTRACT

The authors discuss transference enactments that occur during cross-cultural supervision. Previous research has shown that few mental health professionals willingly talk about race during supervision and that White supervisees experience significant difficulty when directly engaged in discussions about race. They introduce a new phenomenon, “stereotypical” transference enactments, as a means for understanding the countertransference Black female clinical supervisors experience during clinical supervision of White supervisees. The findings indicated that effective cross-cultural supervision should address the intersectionality of race and gender to enhance the development of multicultural clinical skills. The clinical and educational challenges are discussed by using two case vignettes.     

Changing attitudes about self-injury prevention management: lessons learned

In the behavioral health environment, nurses often use continuous staff monitoring and, at times, physical restraints, to manage the severity of patients' self-injury. Both options put staff in control, are the most restrictive in nature, and can be financially draining on the hospital's budget. This can result in negative reactions by both patients and staff. It is important to develop a program that will empower patients to control their behavior and allow staff to be aware of their perceptions and attitudes toward patients who self-injure. This article describes the leadership initiative that drove the development, training, and implementation of a self-injury prevention project and the lessons learned by staff.     

A Preliminary Examination of Covitality as Integrated Well-Being in College Students

The emergence of positive psychology has generated increased interest about the correlates of positive psychological functioning. Researchers have identified and studied various positive psychological constructs (e.g., hope, optimism, self-efficacy, gratitude, and life satisfaction) and found them to covary and to be positively associated with optimal human functioning and negatively associated with mental illness. This study of 528 college students examined the co-occurrence of selected positive psychological traits and explored their relations with a proposed second-order latent construct called covitality and with psychological well-being. Structural equation modeling examined each first-order positive psychology construct related to the second-order concept of covitality. Findings supported the second-order latent factor model of covitality, which was also significantly related to indicators of psychological well-being. Implications for theory development related to understanding positive human resources and applications within the context of college student populations are discussed.     

Ninety Years in the World of Work in America

Parsons's tripartite model suggests that gaining information about the world of work is a critical factor in vocational decision making. This article compares and contrasts data from around 1909, when F. Parsons's Choosing a Vocation was published, with contemporary data on the workplace and the American worker. Data on other contextual factors, such as demographic trends, are also presented. There are surprising similarities between Parsons's time and the present, and also obvious differences. The author suggests that having information about occupations is still an essential component of career counseling, and ideas are presented for updating knowledge about the increasingly complex world of work.