Low back pain in physical therapists: a cultural approach to analysis and intervention

Low back pain is one of the most prevalent work related injuries in the physical therapy profession. New graduates and therapists working in rehabilitation and acute care hospitals are at the highest risk for developing low back pain [9]. Although physical therapists are trained in maintaining proper body mechanics and preventing work related injuries, between 30% and 63% of therapists will experience low back pain at some point in their careers [2,4,9]. The culture of physical therapy is one of the primary factors contributing to this problem, with many therapists reporting that their decision to use back pain preventive strategies depends on their colleagues' use of these strategies. The authors will use Green and Kreuter's PRECEDE-PROCEED model to identify behavioral, environmental, educational and ecological factors contributing to the problem; then will propose a health promotion intervention using the social action theory at the community level to decrease work-related low back pain in physical therapists while simultaneously addressing the culture of physical therapy.     

Computationally tractable approximate and smoothed Polya trees

A discrete approximation to the Polya tree prior suitable for latent data is proposed that enjoys surprisingly simple and efficient conjugate updating. This approximation is illustrated in two applied contexts: the implementation of a nonparametric meta-analysis involving studies on the relationship between alcohol consumption and breast cancer, and random intercept Poisson regression for Ache armadillo hunting treks. The discrete approximation is then smoothed with Gaussian kernels to provide a smooth density for use with continuous data; the smoothed approximation is illustrated on a classic dataset on galaxy velocities and on recent data involving breast cancer survival in Louisiana.     

Generalized accelerated failure time spatial frailty model for arbitrarily censored data

Flexible incorporation of both geographical patterning and risk effects in cancer survival models is becoming increasingly important, due in part to the recent availability of large cancer registries. Most spatial survival models stochastically order survival curves from different subpopulations. However, it is common for survival curves from two subpopulations to cross in epidemiological cancer studies and thus interpretable standard survival models can not be used without some modification. Common fixes are the inclusion of time-varying regression effects in the proportional hazards model or fully nonparametric modeling, either of which destroys any easy interpretability from the fitted model. To address this issue, we develop a generalized accelerated failure time model which allows stratification on continuous or categorical covariates, as well as providing per-variable tests for whether stratification is necessary via novel approximate Bayes factors. The model is interpretable in terms of how median survival changes and is able to capture crossing survival curves in the presence of spatial correlation. A detailed Markov chain Monte Carlo algorithm is presented for posterior inference and a freely available function frailtyGAFT is provided to fit the model in the R package spBayesSurv. We apply our approach to a subset of the prostate cancer data gathered for Louisiana by the surveillance, epidemiology, and end results program of the National Cancer Institute.     

Remarriage,Cohabitation, and Changes in Mothering Behavior

We used data from two waves of the National Survey of Families and Household to investigate changes in mothering behavior associated with remarriage or cohabitation by single mothers. We considered three dimensions of mothering: (a) time and supervision, (b) harsh discipline, and (c) relationship quality. Mothers and children agreed that mothers who remained in new partnerships used harsh discipline less frequently than mothers who remained single or whose new partnership had ended by the second interview. Mothers reported less supervision if they had experienced a disrupted partnership, whereas children reported less supervision if their mothers remained in a new partnership at the second interview. Children but not mothers reported better relationships with mothers in partnerships at the second interview, compared with children whose mothers remained single or whose new partnership had ended. Only a small part of the differences in harsh discipline, and none of the other observed differences, could be explained by maternal or family characteristics or by mothering behavior and relationships in the first interview. Although cohabiting partnerships were more likely to end than were marriages, we found no differences in effects of cohabiting or marital partnerships, net of their status at the second interview.     

Digital test assembly of truck parts with the IMMA-tool--an illustrative case

Several digital human modelling (DHM) tools have been developed for simulation and visualisation of human postures and motions. In 2010 the DHM tool IMMA (Intelligently Moving Manikins) was introduced as a DHM tool that uses advanced path planning techniques to generate collision free and biomechanically acceptable motions for digital human models (as well as parts) in complex assembly situations. The aim of the paper is to illustrate how the IPS/IMMA tool is used at Scania CV AB in a digital test assembly process, and to compare the tool with other DHM tools on the market. The illustrated case of using the IMMA tool, here combined with the path planner tool IPS, indicates that the tool is promising. The major strengths of the tool are its user friendly interface, the motion generation algorithms, the batch simulation of manikins and the ergonomics assessment methods that consider time.     

Semiparametric inference for survival models with step process covariates

The authors consider Bayesian methods for fitting three semiparametric survival models, incorporating time‐dependent covariates that are step functions. In particular, these are models due to Cox [Cox ( 1972 ) Journal of the Royal Statistical Society, Series B, 34, 187–208], Prentice & Kalbfleisch and Cox & Oakes [Cox & Oakes ( 1984 ) Analysis of Survival Data, Chapman and Hall, London]. The model due to Prentice & Kalbfleisch [Prentice & Kalbfleisch ( 1979 ) Biometrics, 35, 25–39], which has seen very limited use, is given particular consideration. The prior for the baseline distribution in each model is taken to be a mixture of Polya trees and posterior inference is obtained through standard Markov chain Monte Carlo methods. They demonstrate the implementation and comparison of these three models on the celebrated Stanford heart transplant data and the study of the timing of cerebral edema diagnosis during emergency room treatment of diabetic ketoacidosis in children. An important feature of their overall discussion is the comparison of semi‐parametric families, and ultimate criterion based selection of a family within the context of a given data set. The Canadian Journal of Statistics 37: 60–79; © 2009 Statistical Society of Canada     

The Gendered Division of Housework and Couples' Sexual Relationships: A Reexamination

Although contemporary couples increasingly express preferences for egalitarian unions, previous research has suggested that sexual intimacy decreases when routine housework is shared. Yet this research was conducted on data that are decades old. To update this work, the authors compared data from the 2006 Marital and Relationship Survey (MARS) and Wave 2 of the National Survey of Families and Households (NSFH2), collected in 1992–1994. The results indicated change in the association between housework arrangements and sexual intimacy across surveys. Although egalitarian arrangements were associated with lower sexual frequency compared to conventional arrangements in the NSFH2, no such difference was found in the MARS. In fact, reported sexual frequency increased across surveys among egalitarian couples only. In addition, how housework was arranged mattered more for sexual satisfaction among MARS couples than NSFH2 couples. These changes appear to result from the increasing role of perceived equity as a mechanism linking the division of housework to sex.     

The smell of distance: Wallace Stegner’s definition of western non-fiction

Wallace Stegner has argued that land, scale, and aridness are defining characteristics of both the American West and writings about the West. Stegner’s definition is analyzed using his own works and Mark Twain’s Roughing It.