The influence of psychological stressors on myoelectrical signal activity in the shoulder region during a data entry task

Psychological stress is suspected to play a key role in the development of work-related musculoskeletal disorders (WMSDs), and work pace may be a primary contributor. The purpose of this study was to observe how psychological stress affects muscle activity recorded from key muscles used to support the shoulder (the trapezius and levator scapulae muscles) during keying tasks. We hypothesized that muscle activity [amplitude of the myoelectric signal (MES)] would increase and the number of periodic rests in muscle activity ('EMG gaps') would decrease when computer work was performed at an increased pace, and with distractions in the environment. Ten healthy volunteers performed three typing tasks (N = no stress; I = stress induced by a work pace reward; IS = stress induced by a work pace reward plus irritation/distraction). Both muscles showed significant increases ( p < .05) in MES amplitude when comparing IS to the N and I conditions, whereas N and I were not different. There was significant reduction in the number of gaps observed during the I and IS conditions (essentially no gaps were observed) as compared to the N condition. Interestingly, MES amplitude measures were capable of preferentially detecting changes in activation due to the distraction stress, whereas the number of EMG gaps preferentially detected the stress of the increase in work pace. The effect of these stressors on heart rate and productivity are also discussed.     

The Relations between Reactivity at 4 Months and Behavioral Inhibition in the Second Year: Replication across Three Independent Samples

This paper examines the predictive relations between two infant temperamental biases assessed at 4 months and inhibited behavior during the first 2 years of life in three independent samples from two research laboratories. Although each sample used slightly different criteria for classifying infants, the results across samples were consistent. Infants of both genders who displayed high levels of motor activity and distress to unfamiliar events were more inhibited at 14 months of age. By 24 months, there were significant sex differences: Boys identified as high reactive were more inhibited than high reactive girls.     

The Relations among Theory of Mind,Behavioral Inhibition,and Peer Interactions in Early Childhood

The current study examined relations among child temperament, peer interaction, and theory of mind (ToM) development. We hypothesized that: (1) children classified as behaviorally inhibited at 24 months would show less ToM understanding at 36 months in comparison to nonbehaviorally inhibited children; (2) children who displayed negative peer interaction behaviors in a peer dyadic interaction at 24 months would exhibit less ToM understanding at 36 months; and (3) behavioral inhibition (BI) and the degree of negative behaviors during a peer interaction would jointly influence ToM development, such that children with both heightened BI and negative peer interaction behaviors would exhibit worse ToM performance than behaviorally inhibited children who did not display negative social behaviors. Both BI and negative peer interaction behaviors were associated with passing fewer ToM tasks. The data revealed that children high in both BI and negative peer interaction behaviors passed fewer ToM tasks at 36 months of age than those high in BI and low in negative peer interactions or those low in BI.     

Fatness as a disability: questions of personal and group identity

Both fat people and disabled people share common barriers to full societal participation and acceptance. While there has been a substantial amount of literature relating to these two groups as separate entities, there is a lack of contemporary research that investigates the relationship between fat and disability identity formation. The purpose of this qualitative study was to engage in a dialogue with fat individuals and explore the construction of their identities – whether or not they identified with having a disability and, if so, whether or not they viewed their fatness as a disability. Interviews with a sample size of seven participants who self‐identified as ‘fat’ revealed an unwillingness to adopt a disability identity based on their fatness.     

Rapid Estimation of Standard Errors of Means for Small Samples

The general impression that precision of an estimator increases with increasing sample size is scrutinized. It is demonstrated that, if the estimator under consideration is an average function, the statement does not hold good when the population elements are drawn with varying probabilities of selection at each draw. An example is presented to illustrate the point.     

Social Capital,Labour Markets,and Job‐Finding in Urban and Rural Regions: comparing paths to employment in prosperous cities and stressed rural communities in Canada1,2

This paper compares paths to employment (job‐finding) in prosperous cities and economically‐stressed rural communities in Canada. Since the pioneering work of Mark Granovetter (1973; 1974 ), sociologists have investigated the role of social capital in job‐finding (specifically, the use of strong and weak social ties to find out about employment opportunities). To date, however, there have been few direct comparisons of job‐finding in urban and rural settings (see Lindsay et al., 2005 ; Wahba and Zenou, 2005 ). Using data from two major surveys and a qualitative interview project, we uncover several important differences in urban and rural paths to employment. First, we find that both strong and weak ties are used more frequently by rural residents to find a job, while city‐dwellers rely more often on formal or impersonal means. Second, we find much stronger evidence of differentiation within rural regions. Long‐time rural residents are much more likely to use strong and weak ties to find employment than are newcomers. However, rural residents who used weak ties as paths to employment have significantly lower incomes. None of these patterns are evident in the cities. Together, these findings lead us to conclude that job‐finding in rural settings is strongly affected by constraints – in the labour market and in social capital resources – that are not present in cities.     

Building better measures of role ambiguity and role conflict: The validation of new role stressor scales

Occupational stress researchers have given considerable attention to role ambiguity and role conflict as predictors of employee health, job attitudes and behaviour. However, the validity of the Rizzo, House, and Lirtzman’s (1970 Rizzo, J. R., House, R. J., &; Lirtzman, S. I. (1970). Role conflict and ambiguity in complex organizations. Administrative Science Quarterly, 15, 150–163. doi: 10.2307/2391486[Crossref], [Web of Science ®] , [Google Scholar]) scales – the most popular role stressor measures – has been a source of disagreement among researchers. In response to the disputed validity of the Rizzo et al. scales, we developed new measures of role ambiguity and role conflict and conducted five studies to examine their psychometric qualities (Study 1 N?=?101 U.S. workers; Study 2 N?=?118 workers primarily employed in the U.S.; Study 3 N?=?135 employed U.S. MBA students; Study 4 N?=?973 members of the U.S. Air Force (USAF); Study 5 N?=?234 workers primarily employed in the U.S.). Across these five studies, we found that the new role stressor scales have desirable psychometric qualities: they displayed high levels of substantive validity, high levels of internal consistency and test–retest reliability, they produced an interpretable factor structure, and we found evidence of their construct validity. We therefore recommend that these new scales be used in future research on role stress.     

Competing risk analysis in a large cardiovascular clinical trial: An APEX substudy

Competing risk methods are time‐to‐event analyses that account for fatal and/or nonfatal events that may potentially alter or prevent a subject from experiencing the primary endpoint. Competing risk methods may provide a more accurate and less biased estimate of the incidence of an outcome but are rarely applied in cardiology trials. APEX investigated the efficacy of extended‐duration betrixaban versus standard‐duration enoxaparin to prevent a composite of symptomatic deep‐vein thrombosis (proximal or distal), nonfatal pulmonary embolism, or venous thromboembolism (VTE)–related death in acute medically ill patients (n = 7513). The aim of the current analysis was to determine the efficacy of betrixaban vs standard‐duration enoxaparin accounting for non‐VTE–related deaths using the Fine and Gray method for competing risks. The proportion of non‐VTE–related death was similar in both the betrixaban (133, 3.6%) and enoxaparin (136, 3.7%) arms, P = .85. Both the traditional Kaplan‐Meier method and the Fine and Gray method accounting for non‐VTE–related death as a competing risk showed equal reduction of VTE events when comparing betrixaban to enoxaparin (HR/SHR = 0.65, 95% 0.42‐0.99, P = 0.046). Due to the similar proportion of non‐VTE–related deaths in both treatment arms and the use of a univariate model, the Fine and Gray method provided identical results to the traditional Cox model. Using the Fine and Gray method in addition to the traditional Cox proportional hazards method can indicate whether the presence of a competing risk, which is dependent of the outcome, altered the risk estimate.