Effect of increased load on scapular kinematics during manual wheelchair propulsion in individuals with paraplegia and tetraplegia

Repetitive loading of the upper extremity musculature during activities like wheelchair propulsion can lead to fatigue of surrounding musculature causing irregular segment kinematics. The goal of this study was to determine the effect of increase in load on the kinematics of the scapula in users with paraplegia and tetraplegia. Data were collected on 18 participants (11 with paraplegia and 7 with tetraplegia) using an electromagnetic motion tracking system (100Hz) and force sensing pushrim (200Hz). The participants propelled under no load and loaded conditions at their customary propulsion velocity. On average a 60N increase in force was elicited with the experimental protocol. Users with tetraplegia showed significant increases (p<.05) in the rate of change of scapular angles in the upward/downward rotation and the retraction/protraction direction under the loaded conditions, whereas users with paraplegia only showed difference in the retraction/protraction rotation direction. Overall both user populations moved towards position of increased downward rotation, anterior tilt and protraction with increase in load hence increasing the risk of impingement. This experiment adds depth to our understanding of dynamic scapular kinematics during wheelchair propulsion under different loading conditions and differences in scapular control between users with paraplegia and tetraplegia.     

The development and initial validation of the Fatigue Sensitivity Questionnaire

ABSTRACT

Currently, there is poor understanding of fatigue and the possible psychological conditions that may underlie chronic fatigue. Although substantial work has been directed to better clinically address fatigue, no work has explored individual differences in expectations or perceptions of the negative consequences associated with fatigue-related symptoms. The goals of this study were to (a) develop and (b) validate a measure of expectations or perceptions of the negative consequences associated with fatigue-related symptoms (e.g. fatigue sensitivity) across two independent samples (N = 1,827; 73.1% female; M_age = 21.68; SD = 4.54) of young adults. Results supported a 10-item measure of fatigue sensitivity, entitled the Fatigue Sensitivity Questionnaire (FSQ). The FSQ demonstrated unidimensionality, excellent internal consistency, and strong convergent and discriminant validity. Overall, the 10-item scale offers a single score that can be employed to measure fatigue sensitivity. Clinically, the FSQ may be a brief, informative, and easily disseminated measure in better understanding and capturing expectations or perceptions about the negative consequences of fatigue. As a research tool, the use of the FSQ may provide broader understanding of vulnerability factors that may influence fatigue-related health outcomes. Future research is needed to test the validity of the FSQ in other samples.     

Vertical gaze direction and the resting posture of the eyes

With horizontal gaze, the resting posture of binocular vergence typically corresponds to a distance of about 1 m. The effect of vertical direction of gaze on this basic resting posture was investigated. The dark vergence of twenty-four subjects was measured while they fixated a dim monocular light-point at vertical directions ranging from -45 degree (lowered) to +30 degrees (elevated). In one condition, gaze was varied by changes in eye position with the head held upright; in a second condition, gaze was varied by changes in head inclination with the eyes held in constant (horizontal) position with respect to the head. In both conditions, dark vergence shifted in the convergent (nearer) direction with lowered gaze and in the divergent (farther) direction with elevated gaze. The effect of varied eye inclination was larger, more variable across subjects, and more stable over time than that of varied head inclination. These findings indicate that multiple mechanisms contribute to gaze-related variations of the resting posture of the eyes. They may help to explain the variations of space perception and visual fatigue that are observed with different gaze inclinations.     

Can organisational safety climate and occupational stress predict work-related driver fatigue?

Road crashes are a significant cause of work-related injury and death. Driver fatigue is thought to cause 20–30% of fatal crashes. The current study utilised a survey to examine the relationship between safety climate, occupational stress and work-related driver fatigue. Drivers (n = 219) from two government organisations responded to items from the job-related tension scale [Kahn, R. L., Wolfe, D. M., Quinn, R. P., & Snoek, J. D. (1964). Organisational stress: Studies in role conflict and ambiguity. Malabar, FL: Krieger Publishing], safety climate questionnaire [Glendon, A., & Litherland, D. (2001). Safety climate factors, group differences and safety behaviour in road construction. Safety Science, 39, 157–188] and purpose-designed items on fatigue-related behaviour. Outcome measures were current self-reported, fatigue-related behaviour and self-reported ‘near (crash) misses’ during the previous 6 months. Together, occupational stress and safety climate predicted fatigue-related behaviour, accounting for 29% of the variance over and above that explained by control variables. Further, logistic regression revealed occupational stress and safety climate to be significant predictors of fatigue-related near misses. Safety climate emerged as a stronger predictor of both fatigue-related behaviour and near misses than occupational stress. Results suggest that organisations can play a part in improving the safety-related behaviours of their workforce through attention to safety climate and occupational stress.     

Effects of mental fatigue on the capacity limits of visual attention

The literature indicates that mental fatigue, due to Time-on-Task (ToT), compromises the ability to ignore distractors. The present study elaborates on this effect by testing whether perceptual load of the target stimuli moderates the ability to ignore distractors under fatigue. Participants (N = 27) performed a visual attention task (an Eriksen flanker task) for 2.5 hours without rest. Target letters were presented at three different perceptual loads and with a peripheral distractor letter. Three target–distractor conditions were tested: congruent, incongruent, and neutral. Results showed that, overall, error rates and reaction times increased with ToT. The detrimental effect of fatigue on performance was most pronounced in the high perceptual load condition. Importantly, however, we also found that fatigue-related ignorance of distractors was compromised in the low perceptual load condition, but not in the medium or high perceptual load condition. This finding is in accordance with the perceptual load theory and refines the knowledge about the declining cognitive performance under fatigue.     

The relationship between acceptance,fatigue, and subjective cognitive impairment in hematologic cancer survivors

Background/Objective: Cancer and its treatment can have a detrimental impact on psychological well-being. Acceptance as the basis of acceptance and commitment therapy (ACT) has shown beneficial effects on depression and anxiety. However, its relationship to fatigue and cognitive impairment has not been investigated. A protective effect of acceptance may open up a new target for psychological intervention.Method: A cross-sectional postal survey was undertaken. 922 hematological cancer survivors (≥ 2.5 years post diagnosis) were recruited through two regional cancer registries in Germany. Acceptance (AAQ-II), fatigue (BFI) and subjective cognitive impairment (AFI) were assessed.Results: Higher levels of acceptance were negatively associated with fatigue and subjective cognitive impairment (R²= .34 and R²= .26, respectively). The relationship between fatigue and fatigue-related impairment of daily life was weaker for survivors with high acceptance.Conclusions: Acceptance is strongly associated with fatigue and subjective cognitive impairment. ACT may be useful to reduce symptoms of fatigue and subjective cognitive impairment in cancer survivors.     

Attention to important versus trivial tasks and salience of fatigue-related symptoms for coronary prone individuals

The present study tested the hypothesis that individuals with the Type A coronary prone behavior pattern focus their attention more on important tasks, and less on trivial tasks than do Type B's. The study used a paradigm in which some subjects worked on math problems (important task) and rated intervening mood items (trivial task), whereas others rated mood items they were to memorize (important task) and worked on intervening math problems (trivial task). All subjects were later tested on recall of mood items. Results indicated that Type A's performed better on math problems and recalled more fatigue-related mood items when the task was important than when it was trivial; for Type B subjects, there was no difference in the number of math problems solved correctly or number of mood items recalled between important and trivial task conditions. Moreover, Type A's reported greater fatigue when mood recall was the important task than when math was the important task, whereas fatigue ratings of Type B's did not differ across these conditions. The findings suggest that Type A's suppress their attention to fatigue-related symptoms only when symptoms are not the objects of focus.     

A data-matching study of the role of fatigue in work-related crashes

This study investigated fatigue involvement in work and nonwork-related road traffic casualty crashes using a dataset formed by linking the New South Wales workers compensation dataset with the New South Wales road traffic crash database. In many crash databases work-relatedness cannot be identified. Other databases, such as workers compensation data provide information on work-related road traffic injury but little on the circumstances of the crash. Probabilistic linkage overcame these problems by matching cases from the workers compensation data to the crash data to produce a new dataset of work-related road traffic casualties. The patterns of fatigue-involvement in these casualty crashes showed similarities between work-related crashes and nonwork-related crashes. Fatigue-involved crashes were more likely to result in fatality, involved higher costs, were more likely to involve heavy and light trucks and to involve illegal alcohol or speeding no matter whether they were work-related or not. Time of crash was the only characteristic that differed between work and nonwork-related crashes. Work-related fatigue-involved crashes tended to occur around dawn whereas work-related non-fatigue crashes occurred in peak hour traffic. Timing of work-related crashes involving fatigue varied little across the 24-h period whereas those not involving fatigue showed an afternoon peak only. While fatigue-related crashes occur in similar ways regardless of work status, strategies for work-related driver fatigue should not be left to be addressed only by general road safety strategies. As there is more control in the workplace over some of the fundamental causes of driver fatigue work-related fatigue management strategies are much more likely to be successful.     

Representation of two geometric features of the environment in the domestic chick (<Emphasis Type="Italic">Gallus gallus</Emphasis>)

We report experiments based on a novel test in domestic chicks (Gallus gallus), designed to examine the encoding of two different geometric features of an enclosed environment: relative lengths of the walls and amplitude of the corners. Chicks were trained to search for a food reward located in one corner of a parallelogram-shaped enclosure. Between trials, chicks were passively disoriented and the enclosure was rotated, making reorientation possible only on the basis of the internal spatial structure of the enclosure. In order to reorient, chicks could rely on two sources of information: the relative lengths of the walls of the enclosure (associated to their left-right sense order) and the angles subtended by walls at corners. Chicks learned the task choosing equally often the reinforced corner and its rotational equivalent. Results of tests carried out in novel enclosures, the shapes of which were chosen ad hoc (1) to induce reorientation based only on the ratio of walls lengths plus sense (rectangular enclosure), or (2) to induce reorientation based only on corner angles (rhombus-shaped enclosure), suggested that chicks encoded both features of the environment. In a third test, in which chicks faced a conflict between these geometric features (mirror parallelogram-shaped enclosure), reorientation seemed to depend on the salience of corner angles. These results shed light on the elements of the environmental geometry which control spatial reorientation, and broaden the knowledge on the geometric representation of space in animals.     

不连续虚拟现实空间中的再定向

虚拟空间的特点之一是具有不连续性, 即在无连接型建筑单元的情况下各个单体间可直接通达的特性。本研究对人在不连续的虚拟空间中的再定向能力进行了探究, 将人类空间再定向能力的研究从现实空间延伸到了虚拟空间, 并研究了人在不同虚拟现实设备中的行为表现差异。结果表明, 人在不连续的虚拟空间中能完成再定向任务, 而虚拟空间中建筑单元的几何信息对人在不连续虚拟空间中的再定向表现无显著影响, 但被试在桌面式虚拟现实中的成绩显著高于在头盔式虚拟现实中的成绩。这些结果表明了人对不连续的虚拟空间的适应性。     

Dopaminergic modulation of incentive motivation in adolescence: age-related changes in signaling, individual differences, and implications for the development of self-regulation

Behavioral activation that is associated with incentive-reward motivation increases in adolescence relative to childhood and adulthood. This quadratic developmental pattern is generally supported by behavioral and experimental neuroscience findings. It is suggested that a focus on changes in dopamine neurotransmission is informative in understanding the mechanism for this adolescent increase in reward-related behavioral activation and subsequent decline into adulthood. Evidence is presented to indicate that incentive-reward motivation is modulated by mesoaccumbens dopamine, and that it increases in adolescence before declining into adulthood because of normative developmental changes at the molecular level. Potential mechanisms of variation in functional mesoaccumbens dopamine transmission are discussed with a focus on the interplay between tonic and phasic modes of dopamine transmission in modulating both general incentive-motivational biases and the efficacy of reward learning during exposure to novel reward experiences. Interactions between individual difference factors and these age-related trends are discussed.     

Effect of head movement on the localization of sounds in the equatorial plane

Five experiments examined the effect of head movement on the localization of sound sources in the equatorial plane. Under most conditions, head movement produces poorer localization for sound sources in the equatorial plane. Only one condition demonstrated an improvement in localization with head movement. The sound source was located toward the side of the head and the source duration was long enough to permit reorientation of the position of the head with re-spect to the sound source.     

Crossover between work and home in dyadic partner relationships

This study aimed at providing insight into the processes underlying crossover between "work" and "home" in dyadic partner relationships. Specifically, we examined to what extent husbands' work demands (work load and overtime hours) and psychological health (fatigue and depressive symptoms) "cross over" to their wives' home demands (home load) and psychological health. These associations were investigated among three couple groups, based on wives' working hours (i.e., more than 20 hours per week, from 1 to 20 hours per week, and not engaged in paid work) (253 couples in total). All husbands worked for at least 35 hours a week. Three possible crossover mechanisms were hypothesized: (i) time-based, (ii) strain-based, and (iii) empathy-based crossover. The results partially supported mechanisms (i) and (ii): when husbands reported higher work load (mechanism i) and more psychological health complaints (mechanism ii), their wives experienced higher home load. The results further supported mechanism (iii) that wives' and husbands' psychological health were associated. It is concluded that crossover from husbands to wives may occur through various mechanisms.     

Effects of negative mood states on risk in everyday decision making

How does negative mood affect risk taking? A brief questionnaire was used to measure state anxiety, depression, and fatigue, and a daily mood diary allowed state and trait (average level) mood to be separated. Studies 1 and 2 used natural moods and Study 3 a mood induction procedure. Risk was assessed using hypothetical everyday choice scenarios. Study 1 showed that riskiness was affected by state fatigue, but not by anxiety and depression. Study 2 showed that increased riskiness over a two - week period was predicted by fatigue changes, after controlling for riskiness and trait and state mood at time 1. Fatigue effects were stronger for more important scenarios, and when state anxiety was also high. In Study 3, covariance analyses showed that the observed increased in riskiness was related to induced fatigue, rather than to anxiety or depression. The effects are discussed in relation to the literature on fatigue effects, and models of mood and cognition.     

Like a Fish Out of Water: Reconsidering Disaster Recovery and the Role of Place and Social Capital in Community Disaster Resilience

In this paper we draw on the findings of a critical, multi-sited ethnographic study of two rural communities affected by a wildfire in British Columbia, Canada to examine the salience of place, identity, and social capital to the disaster recovery process and community disaster resilience. We argue that a reconfiguration of disaster recovery is required that more meaningfully considers the role of place in the disaster recovery process and opens up the space for a more reflective and intentional consideration of the disorientation and disruption associated with disasters and our organized response to that disorientation. We describe a social-psychological process, reorientation, in which affected individuals and communities navigate the psychological, social and emotional responses to the symbolic and material changes to social and geographic place that result from the fire's destruction. The reorientation process emphasizes the critical importance of place not only as an orienting framework in recovery but also as the ground upon which social capital and community disaster resilience are built. This approach to understanding and responding to the disorientation of disasters has implications for community psychologists and other service providers engaged in supporting disaster survivors. This includes the need to consider the complex dynamic of contextual and cultural factors that influence the disaster recovery process.     

Making decisions with the future in mind: Developmental and comparative identification of mental time travel

Mechanisms that produce behavior which increase future survival chances provide an adaptive advantage. The flexibility of human behavior is at least partly the result of one such mechanism, our ability to travel mentally in time and entertain potential future scenarios. We can study mental time travel in children using language. Current results suggest that key developments occur between the ages of three to five. However, linguistic performance can be misleading as language itself is developing. We therefore advocate the use of methodologies that focus on future-oriented action. Mental time travel required profound changes in humans’ motivational system, so that current behavior could be directed to secure not just present, but individually anticipated future needs. Such behavior should be distinguishable from behavior based on current drives, or on other mechanisms. We propose an experimental paradigm that provides subjects with an opportunity to act now to satisfy a need not currently experienced. This approach may be used to assess mental time travel in nonhuman animals. We conclude by describing a preliminary study employing an adaptation of this paradigm for children.     

How professional pilots perceive interactions of working conditions,rosters, stress,sleep problems,fatigue and mental health. A qualitative content analysis

IntroductionSo far, no qualitative content analysis (QCA) has analysed pilots’ experiences and perceptions regarding weaknesses of fatigue risk management (FRM), flight time limitations (FTL), rosters, fatigue-severity, sleep problems, and how they relate to pilots’ mental health and well-being.ObjectiveThis research analyses pilots’ described perceptions of stress, fatigue, aviation safety and how regulations like FTL can affect their health and well-being.MethodIn total, 119 international pilots described their perceptions of FTL, rosters, aviation safety, and how they relate to fatigue and health. The QCA was conducted to analyse interactions of working conditions, stressors, fatigue, sleep problems and mental health of EASA-based and Australian pilots.ResultsAlthough pilots were rostered for only 60.8% to 62.5% of the legally allowed duty and flight hours/month, 78.6% reported severe or very high fatigue, 22.8% significant depression, 12.3% significant anxiety symptoms, 10.5% reported significant depression and anxiety symptoms. Pilots uttered severe concerns about FTL, sleep restrictions associated with early starts, minimum rest, etc. Pilots also expressed distinct fears regarding more fatigue-related crashes, and how adverse working conditions, work-related and psychosocial stress could impair their health.ConclusionsThis QCA provided valuable insights into interactions of working conditions, fatigue, sleep restrictions, physical and mental health. Progressive health impairment due to lack of sleep and accumulated fatigue promote burnout, mental and physical health problems, which not only threaten flight safety, but also sustainability of aviation.