Posture and motion variability in non-repetitive manual materials handling tasks

In developing a motion prediction model it is important to initially consider the sources of variability that a model should reproduce. This initial step is followed by model evaluation, where the variability predicted by the model can be a useful test parameter. An existing lifting-motion dataset collected under controlled laboratory conditions was employed here to evaluate quantitatively some important sources of variability for lift motion modeling. The main source of variability was the segment being analyzed, which accounted for more than 20% of the overall variability. There was substantial left-right symmetry in individual segment variability estimates, which were largest for the upper arm segment and tended to be larger for the upper limbs than the lower limbs. Task-related factors accounted for variability mainly as a function of the segment being considered. Within-participant variability contributions to the dataset were relatively small, whereas the contribution of between-participants variability was dependent on the segment (as large as 50%) and could indicate different lifting strategies across participants. Variability was found to remain relatively constant across the different stages of the lifting movements. Implications of these results for the development and evaluation of motion prediction models are presented. Specifically, while task characteristics may be important modifiers of the mean segment trajectory during a lifting movement, their influence on variability differs based on the segment that is being considered. The relevance of the findings is discussed in terms of their utility in the ergonomic design of tasks and work spaces.     

ADHD and female specific concerns: a review of the literature and clinical implications

ADHD was once thought of as a predominantly male disorder. While this may be true for ADHD in childhood, extant research suggests that the number of women with ADHD may be nearly equal to that of men with the disorder (Faraone et al., 2000). There is accumulating research which clearly indicates subtle but important sex differences exist in the symptom profile, neuropathology and clinical course of ADHD. Compared to males with ADHD, females with ADHD are more prone to have difficulties with inattentive symptoms than hyperactive and impulsive symptoms, and females often receive a diagnosis of ADHD significantly later than do males (Gaub & Carlson, 1997; Gershon, 2002a, 2002b). Emerging evidence suggests differences exist in the neuropathology of ADHD, and there are hormonal factors which may play an important role in understanding ADHD in females. Although research demonstrates females with ADHD differ from males in important ways, little research exists that evaluates differences in treatment response. Given the subtle but important differences in presentation and developmental course of ADHD, it is essential that both clinical practice and research be informed by awareness of these differences in order to better identify and promote improved quality of care to girls and women with ADHD.     

Replies

John Fischer challenges me to defend my arguments regarding the badness of death; I sharpen my position, but make some concessions, discussing the possibility of postmortem harm. In response to John Deigh, I defend the account of disgust given in Hiding from Humanity, together with the research of Paul Rozin that I follow there. I discuss Patrick Devlin’s conservative position, agree that we need to object to its emphasis on solidarity, not only to its emphasis on disgust, and argue that Deigh’s statement of Devlin’s position is too kind to Devlin. In response to Henry Richardson, I summarize my reasons for thinking that the classical social contract tradition cannot handle well the problems posed by the issue of justice for people with disabilities, and that even Rawls’s position requires major modification if it is to do so. I explore differences between Richardson’s position and my own on the issues of self-respect, liberty, and primary goods.     

Examining adversarial growth in illness: The factor structure of the silver lining questionnaire (SLQ-38)

The Silver Lining Questionnaire (SLQ-38) is purported to measure 10 aspects of adversarial growth in illness. To date however, no empirical evidence exists to support this claim. Hence the aim of this study was to investigate the factor structure of the SLQ-38 in a sample of 560 individuals with multiple sclerosis (MS), cancer, cardiac, and renal disease. The results demonstrate that 24 SLQ-38 items can be factored into five subscales: improved personal relationships, greater appreciation for life, positive influence on others, personal inner strength and changes in life philosophy, all of which are in accordance with the literature on adversarial growth. Individuals with MS experienced lower adversarial growth compared to other illness groups. Gender, age and time since diagnosis were unrelated to adversarial growth in illness. The utility of the revised SLQ-38 is discussed along with suggestions for future research on the convergent and divergent validity of this revised instrument.     

Putative behavioral history effects and aggression maintained by escape from therapists

Differentially higher rates of aggression in treatment sessions occurred in the presence of two staff members who had previously worked with the participant at another facility. Adding an edible reinforcer for compliance and the absence of aggression in sessions conducted by these two staff members decreased aggression to rates similar to those obtained with less familiar therapists. Results suggest that embedding positive reinforcement within a demand context may reduce the aversiveness of therapists correlated with a history of demand situations.