How does tooth cusp radius of curvature affect brittle food item processing?

Tooth cusp sharpness, measured by radius of curvature (RoC), has been predicted to play a significant role in brittle/hard food item fracture. Here, we set out to test three existing hypotheses about this relationship: namely, the Blunt and Strong Cusp hypotheses, which predict that dull cusps will be most efficient at brittle food item fracture, and the Pointed Cusp hypothesis, which predicts that sharp cusps will be most efficient at brittle food item fracture using a four cusp bunodont molar. We also put forth and test the newly constructed Complex Cusp hypothesis, which predicts that a mixture of dull and sharp cusps will be most efficient at brittle food item fracture. We tested the four hypotheses using finite-element models of four cusped, bunodont molars. When testing the three existing hypotheses, we assumed all cusps had the same level of sharpness (RoC), and gained partial support for the Blunt Cusp hypotheses. We found no support for the Pointed Cusp or Strong Cusp hypotheses. We used the Taguchi sampling method to test the Complex Cusps hypothesis with a morphospace created by independently varying the radii of curvature of the four cusps in the buccolingual and mesiodistal directions. The optimal occlusal morphology for fracturing brittle food items consists of a combination of sharp and dull cusps, which creates high stress concentrations in the food item while stabilizing the food item and keeping the stress concentrations in the enamel low. This model performed better than the Blunt Cusp hypothesis, suggesting a role for optimality in the evolution of cusp form.     

Mind the gap: Expanding communication options in decentralized discrete-event control

Frameworks that incorporate communication into decentralized supervisory control theory address the following problem: find locations in the evolution of the plant behavior where supervisors send information so that a supervisor that was unable to make the correct control decision prior to receiving external information, is now capable of making the correct control decision. Existing solutions to this problem identify an earliest and a latest placement where the communication protocol leads to the synthesis of a correct control solution. In addition to the first and last communication opportunities, there may be a selection of intermediate possibilities where communication would also produce the correct control solution. We present a computable procedure to identify a broader range of suitable communication locations.     

Mindfulness is associated with fewer PTSD symptoms, depressive symptoms, physical symptoms, and alcohol problems in urban firefighters.

Objective: This study investigated the association between mindfulness, other resilience resources, and several measures of health in 124 urban firefighters. Method: Participants completed health measures of posttraumatic stress disorder (PTSD) symptoms, depressive symptoms, physical symptoms, and alcohol problems and measures of resilience resources including mindfulness, optimism, personal mastery, and social support. The Mindful Awareness and Attention Scale (MAAS; Brown & Ryan, 2003) was used to assess mindfulness. Participants also completed measures of firefighter stress, number of calls, and years as a firefighter as control variables. Hierarchical multiple regressions were conducted with the health measures as the dependent variables with 3 levels of independent variables: (a) demographic characteristics, (b) firefighter variables, and (c) resilience resources. Results: The results showed that mindfulness was associated with fewer PTSD symptoms, depressive symptoms, physical symptoms, and alcohol problems when controlling for the other study variables. Personal mastery and social support were also related to fewer depressive symptoms, firefighter stress was related to more PTSD symptoms and alcohol problems, and years as a firefighter were related to fewer alcohol problems. Conclusions: Mindfulness may be important to consider and include in models of stress, coping, and resilience in firefighters. Future studies should examine the prospective relationship between mindfulness and health in firefighters and others in high-stress occupations. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Using the e-SOFTA for video training and research on alliance-related behavior.

In this article, we describe a specific technology for training/supervision and research on the working alliance in either individual or couple/family therapy. The technology is based on the System for Observing Family Therapy Alliances (SOFTA; Friedlander, Escudero, & Heatherington, 2006), which contains four conceptual dimensions (Engagement in the Therapeutic Process, Emotional Connection with the Therapist, Safety within the Therapeutic System, and Shared Sense of Purpose within the Family), observational rating tools (SOFTA-o), and self-report measures (SOFTA-s) shown to be important indicators of therapeutic progress. The technology, e-SOFTA, is a computer program (available for PC downloading free of charge) that can be used to rate client(s) and therapist on the specific SOFTA-o behaviors that contribute to or detract from a strong working alliance in each dimension. In addition to providing time-stamped frequencies of alliance-related behaviors, e-SOFTA allows users to link the observed behaviors to qualitative comments and to compare one person's rating of a session to that of another person. Suggestions are provided for using e-SOFTA in research, in didactic training, and in supervision, including a specific training module for introducing graduate students to the working alliance and assessing their observational and executive skills. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Sociomateriality and boundary objects in information systems development

Information systems (IS) development is a complex organisational activity involving multiple stakeholders who interact with various artefacts in order to facilitate understanding and cooperation across diverse knowledge domains. A considerable body of work has analysed such artefacts as boundary objects, focusing on their interpretive flexibility across communities of practice. Increasing interest in the materiality of organisational practices directs attention to how such objects result from the performance of sociomaterial relations. This paper draws on these two strands of research to complement the analysis of project-related artefacts as boundary objects with a sociomaterial perspective on such objects and the practices within which they are constituted. The contribution of this combined approach is illustrated using the findings of a longitudinal case study of IS development. We trace the production and use of a prototype, the various people and practices with which it was associated, the multiple sociomaterial configurations that constituted it as a boundary object, and the social and material consequences of its use. The utilisation of sociomateriality as a theoretical lens enables us to further our understanding of how project-related artefacts act as boundary objects, and in doing so, constitute IS development as a sociomaterial practice.     

Exploring physical exposures and identifying high-risk work tasks within the floor layer trade

Introduction

Floor layers have high rates of musculoskeletal disorders yet few studies have examined their work exposures. This study used observational methods to describe physical exposures within floor laying tasks.

Methods

We analyzed 45 videos from 32 floor layers using Multimedia-Video Task Analysis software to determine the time in task, forces, postures, and repetitive hand movements for installation of four common flooring materials. We used the WISHA checklists to define exposure thresholds.

Results

Most workers (91%) met the caution threshold for one or more exposures. Workers showed high exposures in multiple body parts with variability in exposures across tasks and for different materials. Prolonged exposures were seen for kneeling, poor neck and low back postures, and intermittent but frequent hand grip forces.

Conclusions

Floor layers experience prolonged awkward postures and high force physical exposures in multiple body parts, which probably contribute to their high rates of musculoskeletal disorders.     

The natural history of cigarette smoking from adolescence to adulthood in a midwestern community sample: Multiple trajectories and their psychosocial correlates.

Previous research on the natural history of smoking has focused on overall group trajectories without considering the possibility of risk subgroup variation. To address this limitation, the authors of the present study aimed to identify subgroups with varying trajectories of smoking behavior. The authors accomplished this within a cohort-sequential study of a large community sample (N?=?8,556) with measurements spanning ages 11–31. After removing 2 a priori groups (abstainers and erratics), the authors empirically identified 4 trajectory groups—early stable smokers, late stable smokers, experimenters, and quitters—and psychosocial variables from adolescence and young adulthood were significantly distinguished among them. Given recent advances in quantitative methods, it is now feasible to consider subgroups of trajectories within an overall longitudinal design. (PsycINFO Database Record (c) 2010 APA, all rights reserved)