Gender Sexuality Alliances and School Safety: Who Benefits Most, and Do Additive School-Led Practices Strengthen the Link?

While Gender and Sexuality Alliances (GSAs) are associated with higher acceptance of sexual diversity and lower bullying-victimization, it is unclear which individual and school-level attributes strengthen these associations. Nationally representative data (N = 1,567 students; Mage = 15.4, SD = 0.16; 34% boys, 66% girls, 51% heterosexual, 49% sexually-diverse after propensity score matching) in 139 Dutch secondary schools were used. Multilevel regression analyses revealed that GSA presence was linked to more inclusive attitudes about sexual diversity and a safer disclosure climate among sexually-diverse students, and lower general bullying-victimization when the school had a GSA combined with school practices to tackle bullying. School professionals and researchers are recommended to recognize the significance of individual and school-level factors that affect GSA correlates.

Arm-support exoskeleton reduces shoulder muscle activity in ceiling construction.

The objective of this study was to assess the efficacy and user's impression of an arm-support exoskeleton in complex and realistic ceiling construction tasks. 11 construction workers performed 9 tasks. We determined objective and subjective efficacy of the exoskeleton by measuring shoulder muscle activity and perceived exertion. User's impression was assessed by questionnaires on expected support, perceived support, perceived hindrance and future intention to use the exoskeleton. Wearing the exoskeleton yielded persistent reductions in shoulder muscle activity of up to 58% and decreased perceived exertion. Participants reported limited perceived hindrance by the exoskeleton, as also indicated by no increase in antagonistic muscle activity. The findings demonstrate the high potential of an arm-support exoskeleton for unloading the shoulder muscles when used in the dynamic and versatile working environment of a ceiling construction worker, which is in line with the consistent intention of the workers to use the exoskeleton in the future.Practitioner Summary: The majority of research focuses on the effect of using an arm-support exoskeleton during isolated postures and prescribed movements. We investigated the efficacy of an exoskeleton during a complex and realistic work, namely ceiling construction. Shoulder muscle activity was lower in almost all tasks when wearing the exoskeleton.

The effect of back muscle fatigue on EMG and kinematics based estimation of low-back loads and active moments during manual lifting tasks.

This study investigated the effects of back muscle fatigue on the estimation of low-back loads and active low-back moments during lifting, using an EMG and kinematics based model calibrated with data from an unfatigued state. Fourteen participants performed lifting tasks in unfatigued and fatigued states. Fatigue was induced through semi-static forward bending. EMG, kinematics, and ground reaction forces were measured, and low-back loads were estimated using inverse dynamics and EMG-driven muscle model. A regression model was developed using data from a set of calibration lifts, and its accuracy was evaluated for unfatigued and fatigued lifts. During the fatigue-inducing task, the EMG amplitude increased by 2.8 %MVC, representing a 38% increase relative to the initial value. However, during the fatigued lifts, the peak EMG amplitude was found to be 1.6 %MVC higher than that observed during the unfatigued lifts, representing a mere 4% increase relative to the baseline unfatigued peak EMG amplitude. Kinematics and low-back load estimates remained unaffected. Regression model estimation errors remained unaffected for 5 kg lifts, but increased by no more than 5% of the peak active low-back moment for 15 kg lifts. We conclude that the regression-based estimation quality of active low-back moments can be maintained during periods of muscle fatigue, although errors may slightly increase for heavier loads.

Field study on the use and acceptance of an arm support exoskeleton in plastering.

Exoskeleton use in day-to-day plastering may face several challenges. Not all plasterer's tasks comprise of movements that will be supported by the exoskeleton and might even be hindered. Furthermore, use in practice might be jeopardised by time pressure, colleagues being negative, discomfort, or any other hindrance of the exoskeleton. We set up a field study, in which 39 plasterers were equipped with an exoskeleton for six weeks, to study exoskeleton usage. Moreover, we studied workload and fatigue, behaviour, productivity and quality, advantages and disadvantages, and acceptance. Exoskeleton use was dependent on the task performed but did not change over the course of the six weeks. For three tasks, higher exoskeleton use was associated with lower perceived loads, although differences were small. Advantages outweighed disadvantages for the majority of our population. This study shows that a majority of plasterers will wear the exoskeleton and is enthusiastic about the load reducing effect. Practitioner summary: For exoskeletons to make an impact on the health and well-being of workers, they need to be applicable in real work situations and accepted by the users. This study shows that 65% of the plasterers in this study want to use the exoskeleton in the future, for specific tasks.

What about the human in human robot collaboration?

In this review we address the human in human robot collaboration (HRC). Although there are different hypotheses on potential effects of HRC on job quality, defined as the quality of the working environment and its effect on the employee's well-being, a comprehensive theory is still lacking. How does HRC influence job quality on an individual level and how can we adapt HRC to boost positivity at work? We identified four job quality related factors that are of relevance in HRC: (1) Cognitive Workload, (2) Collaboration Fluency, (3) Trust, and (4) Acceptance and Satisfaction. Increasing awareness and being able to adapt the robot to the individual operator are crucial to improve the aforementioned factors. Implementing predictable robots, that offer a clear advantage to the human and take into account operators' preferences, will bring us closer to a human-centered collaboration. Practitioner Summary: The effect of human robot collaboration (HRC) on job quality is still under debate. Design characteristics of HRC, such as collaboration design, robot design, and workplace design affect job quality related factors. Using a participatory design approach, as to align robot capabilities to end-users' preferences, will enhance HRC and improve job quality. Abbreviations: HRC: human robot collaboration; OECD: organisation for economic co-operation and development.

Trends over Time in Adolescent Emotional Wellbeing in the Netherlands, 2005-2017: Links with Perceived Schoolwork Pressure, Parent-Adolescent Communication and Bullying Victimization.

In some Scandinavian countries, the United Kingdom and the United States, there is evidence of a dramatic decline in adolescent emotional wellbeing, particularly among girls. It is not clear to what extent this decline can be generalised to other high-income countries. This study examines trends over time (2005-2009-2013-2017) in adolescent wellbeing in the Netherlands, a country where young people have consistently reported one of the highest levels of wellbeing across Europe. It also assesses parallel changes over time in perceived schoolwork pressure, parent-adolescent communication, and bullying victimization. Data were derived from four waves of the nationally representative, cross-sectional Dutch Health Behaviour in School-aged Children study (N = 21,901; 49% girls; Mage = 13.78, SD = 1.25). Trends in emotional wellbeing (i.e., emotional symptoms, psychosomatic complaints, life satisfaction) were assessed by means of multiple regression analyses with survey year as a predictor, controlling for background variables. Emotional wellbeing slightly declined among adolescent boys and girls between 2009 and 2013. A substantial increase in perceived schoolwork pressure was associated with this decline in emotional wellbeing. Improved parent-adolescent communication and a decline in bullying victimization may explain why emotional wellbeing remained stable between 2013 and 2017, in spite of a further increase in schoolwork pressure. Associations between emotional wellbeing on the one hand and perceived schoolwork pressure, parent-adolescent communication, and bullying victimization on the other were stronger for girls than for boys. Overall, although increasing schoolwork pressure may be one of the drivers of declining emotional wellbeing in adolescents, in the Netherlands this negative trend was buffered by increasing support by parents and peers. Cross-national research into this topic is warranted to examine the extent to which these findings can be generalised to other high-income countries.

Revising the self-report strengths and difficulties questionnaire for cross-country comparisons of adolescent mental health problems: the SDQ-R.

AIMS: The Strengths and Difficulties Questionnaire (SDQ) has been used in many epidemiological studies to assess adolescent mental health problems, but cross-country comparisons of the self-report SDQ are scarce and so far failed to find a good-fitting, common, invariant measurement model across countries. The present study aims to evaluate and establish a version of the self-report SDQ that allows for a valid cross-country comparison of adolescent self-reported mental health problems. METHODS: Using the Health Behaviour in School-aged Children study, the measurement model and measurement invariance of the 20 items of the self-report SDQ measuring adolescent mental health problems were evaluated. Nationally representative samples of 11-, 13- and 15-year old adolescents (n = 33 233) from seven countries of different regions in Europe (Bulgaria, Germany, Greece, the Netherlands, Poland, Romania, Slovenia) were used. RESULTS: In order to establish a good-fitting and common measurement model, the five reverse worded items of the self-report SDQ had to be removed. Using this revised version of the self-report SDQ, the SDQ-R, partial measurement invariance was established, indicating that latent factor means assessing conduct problems, emotional symptoms, peer relationships problems and hyperactivity-inattention problems could be validly compared across the countries in this study. Results showed that adolescents in Greece scored relatively low on almost all problem subscales, whereas adolescents in Poland scored relatively high on almost all problem subscales. Adolescents in the Netherlands reported the most divergent profile of mental health problems with the lowest levels of conduct problems, low levels of emotional symptoms and peer relationship problems, but the highest levels of hyperactivity-inattention problems. CONCLUSIONS: With six factor loadings being non-invariant, partial measurement invariance was established, indicating that the 15-item SDQ-R could be used in our cross-country comparison of adolescent mental health problems. To move the field of internationally comparative research on adolescent mental health forward, studies should test the applicability of the SDQ-R in other countries in- and outside Europe, continue to develop the SDQ-R as a cross-country invariant measure of adolescent mental health, and examine explanations for the found country differences in adolescent mental health problems.

Effect of horizontal pick and place locations on shoulder kinematics.

In this study the effects of horizontal bin locations in an order picking workstation on upper arm elevation, trunk inclination and hand use were investigated. Eight subjects moved (self-paced) light or heavy products (0.2 and 3.0 kg) from a central product bin to an inner or outer order bin (at 60 or 150 cm) on the left or right side of the workstation, while movements were recorded. The outer compared to inner bin location resulted in more upper arm elevation and trunk inclination per work cycle, both in terms of number of peak values and in terms of time integrals of angles (which is a dose measure over time). Considering the peak values and time integrals per minute (instead of per work cycle), these effects are reduced, due to the higher cycle times for outer bins. Hand use (left, right or both) was not affected by order bin locations.

Temporal strategy and performance during a fatiguing short-cycle repetitive task.

This study investigated temporal changes in movement strategy and performance during fatiguing short-cycle work. Eighteen participants performed six 7-min work blocks with repetitive reaching movements at 0.5 Hz, each followed by a 5.5-min rest break for a total duration of 1 h. Electromyography (EMG) was collected continuously from the upper trapezius muscle, the temporal movement strategy and timing errors were obtained on a cycle-to-cycle basis, and perceived fatigue was rated before and after each work block. Clear signs of fatigue according to subjective ratings and EMG manifestations developed within each work block, as well as during the entire hour. For most participants, timing errors gradually increased, as did the waiting time at the near target. Changes in temporal movement strategy were negatively correlated with changes in the level and variability of EMG, suggesting that an adaptive temporal strategy offset the development of unstable motor solutions in this fatiguing, short-cycle work. PRACTITIONER SUMMARY: Sustained performance of operators is essential to maintain competitiveness. In this study of repetitive work, participants gradually changed their temporal movement strategy, for possibly alleviating the effects of fatigue. This suggests that in order to effectively counteract fatigue and sustain performance, industrial production should allow extensive spatial and temporal flexibility.

Individual and environmental predictors of health risk behaviours among Dutch adolescents: the HBSC study.

OBJECTIVE: To examine unique and common predictors of tobacco smoking, binge drinking, cannabis smoking, early sexual intercourse and multiple health risk behaviours. STUDY DESIGN: Cross-sectional survey study. METHODS: The Dutch Health Behaviour in School-aged Children (HBSC) study was used to provide data on 1742 adolescents aged 15 and 16 years of age. This study focused on a variety of individual and environmental predictors of health risk behaviours, tapping into four domains (mental health, family, peers and school), retrieved by adolescent self-reports and corrected for sociodemographic variables. Logistic and linear regression analyses were performed. RESULTS: Unique predictors (i.e., gender, low and very low education level, general health, hyperactivity problems, conduct problems, incomplete family, religion, knowledge of mother, parental rules on alcohol drinking, time spent with friends, number of friends, perceived tobacco use of classmates, truancy) were identified. In addition, common predictors (i.e., permissive rules on alcohol drinking and much time spent with friends) were also identified, explaining an increase in engagement in all investigated health risk behaviours in adolescence, including multiple risk behaviours. CONCLUSIONS: A prevention strategy targeting restrictive parenting and time spent with friends may be effective to reduce/discourage engagement in health risk behaviours.

What is the evidence for less shift work tolerance in older workers?

This paper explores the suggestion that older people would be less tolerant to shift work. Field studies on age-shift work interaction effects on sleep, fatigue, performance, accidents and health were reviewed. Studies on age-shift (morning, afternoon, night) and age-shift system (roster) interactions were also reviewed. In nine studies, shift and day workers were compared and interactions with age were addressed. Two studies reported more problems in older people, four studies reported opposite results, while in five studies no significant age-shift work interaction was observed. From across-shift comparisons (six studies), it was deduced that older compared with younger workers have more sleep problems with night shifts, while the opposite is true for morning shifts. This review did find some differences between older and younger workers, but did not find evidence for the suggestion of more shift work problems in older workers. STATEMENT OF RELEVANCE: This systematic review reveals the limited evidence that exists concerning shift work tolerance in older workers, highlighting an area for future research. Some interactions between age and shift type and shift system have been found, however. In view of these, it is argued that age-specific aspects should be considered in shift work planning.

The effect of work pace on workload, motor variability and fatigue during simulated light assembly work.

This study investigated the effect of work pace on workload, motor variability and fatigue during light assembly work. Upper extremity kinematics and electromyography (EMG) were obtained on a cycle-to-cycle basis for eight participants during two conditions, corresponding to "normal" and "high" work pace according to a predetermined time system for engineering. Indicators of fatigue, pain sensitivity and performance were recorded before, during and after the task. The level and variability of muscle activity did not differ according to work pace, and manifestations of muscle fatigue or changed pain sensitivity were not observed. In the high work pace, however, participants moved more efficiently, they showed more variability in wrist speed and acceleration, but they also made more errors. These results suggest that an increased work pace, within the range addressed here, will not have any substantial adverse effects on acute motor performance and fatigue in light, cyclic assembly work. STATEMENT OF RELEVANCE: In the manufacturing industry, work pace is a key issue in production system design and hence of interest to ergonomists as well as engineers. In this laboratory study, increasing the work pace did not show adverse effects in terms of biomechanical exposures and muscle fatigue, but it did lead to more errors. For the industrial engineer, this observation suggests that an increase in work pace might diminish production quality, even without any noticeable fatigue being experienced by the operators.

The Health Behaviour in School-aged Children (HBSC) study: methodological developments and current tensions.

OBJECTIVES: To describe the methodological development of the HBSC survey since its inception and explore methodological tensions that need to be addressed in the ongoing work on this and other large-scale cross-national surveys. METHODS: Using archival data and conversations with members of the network, we collaboratively analysed our joint understandings of the survey's methodology. RESULTS: We identified four tensions that are likely to be present in upcoming survey cycles: (1) maintaining quality standards against a background of rapid growth, (2) continuous improvement with limited financial resources, (3) accommodating analysis of trends with the need to improve and adapt questionnaire content, and (4) meeting the differing requirements of scientific and policy audiences. CONCLUSIONS: While these challenges are not trivial, the structure of the HBSC network and its long-term experience in working through such challenges renders it likely that HBSC can provide a model of other similar studies facing these tensions.

Electromyographical manifestations of muscle fatigue during different levels of simulated light manual assembly work.

The purpose of this study was to determine whether objective electromyographical manifestations of muscle fatigue develop in the upper trapezius muscle in two assembly tasks involving contractions of different low-intensity levels (8% and 12% MVC) and whether these indications of fatigue are homogeneously distributed across different muscle parts. Ten subjects performed an assembly task for 3 h. EMG was recorded using four pairs of bipolar electrodes over the left and right trapezius muscles during the task itself and during isometric test contractions. Both recordings (during task and test) showed a significant decrease in the mean power frequency (MPF), at both intensity levels while the amplitude remained constant. A regression analysis showed significantly different temporal patterns for the MPF decrease for the two intensities. No differences in manifestations of muscle fatigue development were found between different parts of the muscle. These results indicate that in a highly repetitive low-intensity task, electromyographical manifestations of muscle fatigue can be observed from signals recorded in the task itself. Furthermore, the rate of development of fatigue manifestations was different between the two assembly tasks. This fatigue development appeared to be homogenous across the muscle.

Fatigue effects on tracking performance and muscle activity.

It has been suggested that fatigue affects proprioception and consequently movement accuracy, the effects of which may be counteracted by increased muscle activity. To determine the effects of fatigue on tracking performance and muscle activity in the M. extensor carpi radialis (ECR), 11 female participants performed a 2-min tracking task with a computer mouse, before and immediately after a fatiguing wrist extension protocol. Tracking performance was significantly affected by fatigue. Percentage time on target was significantly lower in the first half of the task after the fatigue protocol, but was unaffected in the latter half of the task. Mean distance to target and the standard deviation of the distance to target were both increased after the fatigue protocol. The changed performance was accompanied by higher peak EMG amplitudes in the ECR, whereas the static and the median EMG levels were not affected. The results of this study showed that subjects changed tracking performance when fatigued in order to meet the task instruction to stay on target. Contrary to our expectations, this did not lead to an overall higher muscle activity, but to a selective increase in peak muscle activity levels of the ECR.

Development of fatigue and discomfort in the upper trapezius muscle during light manual work.

Optimization of the temporal aspects of task design requires a better understanding of the development of muscle fatigue in the neck and shoulder region over time. The objective of the study was to investigate this in two production companies and to determine the relationship between objective and subjective estimates of fatigue. Indicators of fatigue were obtained through electromyography (EMG) during test contractions and ratings of perceived discomfort. EMG amplitude increased during the day in both case studies while mean power frequency decreased only in one case. In both cases, a more detailed frequency analysis of the EMG signals showed an increase in lower frequency power accompanied by a decrease in higher frequency power. Local perceived discomfort in the neck and shoulder increased over the course of the day in both cases. However, no clear relationship between perceived discomfort and objective indicators of fatigue was found. Obtaining sufficient sensitivity to detect effects of temporal aspects of task design probably requires complementary or more refined methods (e.g. EMG arrays, mechanomyography).

Association between objective and subjective measurements of comfort and discomfort in hand tools.

In the current study, the relationship between objective measurements and subjective experienced comfort and discomfort in using handsaws was examined. Twelve carpenters evaluated five different handsaws. Objective measures of contact pressure (average pressure, pressure area and pressure-time (P-t) integral) in static and dynamic conditions, muscle activity (electromyography) of five muscles of the upper extremity, and productivity were obtained during a sawing task. Subjective comfort and discomfort were assessed using the comfort questionnaire for hand tools and a scale for local perceived discomfort (LPD). We did not find any relationship between muscle activity and comfort or discomfort. The P-t integral during the static measurement (beta=-0.24, p<0.01) was the best predictor of comfort and the pressure area during static measurement was the best predictor of LPD (beta=0.45, p<0.01). Additionally, productivity was highly correlated to comfort (beta=0.31, p<0.01) and discomfort (beta=-0.49, p<0.01).

Identifying predictors of comfort and discomfort in using hand tools.

The aim of the study was to identify predictors of comfort and discomfort in using hand tools. For this purpose, the comfort questionnaire for hand tools (CQH) was developed based on the results of a previous study. In the current study, four screwdrivers were evaluated on comfort (expected comfort at first sight and comfort after short time use) using the CQH and discomfort (local perceived discomfort). The results showed that expected comfort at first sight was predicted by aesthetics. Additionally, functionality and physical interaction, and adverse body effects were the major predictors of overall comfort after short time use. Discomfort was predicted by adverse body effects only. It is concluded that comfort and discomfort in using hand tools have partly the same underlying factors: discomfort feelings also affect the comfort experience.

Identifying factors of comfort in using hand tools.

To design comfortable hand tools, knowledge about comfort/discomfort in using hand tools is required. We investigated which factors determine comfort/discomfort in using hand tools according to users. Therefore, descriptors of comfort/discomfort in using hand tools were collected from literature and interviews. After that, the relatedness of a selection of the descriptors to comfort in using hand tools was investigated. Six comfort factors could be distinguished (functionality, posture and muscles, irritation and pain of hand and fingers, irritation of hand surface, handle characteristics, aesthetics). These six factors can be classified into three meaningful groups: functionality, physical interaction and appearance. The main conclusions were that (1) the same descriptors were related to comfort and discomfort in using hand tools, (2) descriptors of functionality are most related to comfort in using hand tools followed by descriptors of physical interaction and (3) descriptors of appearance become secondary in comfort in using hand tools.

Lumbar loading during lifting: a comparative study of three measurement techniques.

Low back loading during occupational lifting is thought to be an important causative factor in the development of low back pain. In order to regulate spinal loading in the workplace, it is necessary to measure it accurately. Various methods have been developed to do this, but each has its own limitations, and none can be considered a "gold standard". The purpose of the current study was to compare the results of three contrasting techniques in order to gain insight into possible sources of error to which each is susceptible. The three techniques were a linked segment model (LSM), an electromyographic (EMG)-based model, and a neural network (NN) that used both EMG and inertial sensing techniques. All three techniques were applied simultaneously to calculate spinal loading when eight volunteers performed a total of eight lifts in a laboratory setting. Averaged results showed that, in comparison with the LSM, the EMG technique calculated a 25.5+/-33.4% higher peak torque and the NN technique a 17.3+/-10.5% lower peak torque. Differences between the techniques varied with lifting speed and method of lifting, and could be attributed to differences in anthropometric assumptions, antagonistic muscle activity, damping of transient force peaks by body tissues, and, specific to the NN, underestimation of trunk flexion. The results of the current study urge to reconsider the validity of other models by independent comparisons.