Fatigue during prolonged intermittent overhead work: reliability of measures and effects of working height

Shoulder pain is prevalent among industrial workers and existing evidence supports that overhead work is an important specific risk factor. Existing guidelines are limited, with overhead work typically recommended to be avoided, and research on overhead work has been mixed in terms of the effects of increasing arm reach. A laboratory-based simulation of overhead work was conducted, at three working heights, in order to facilitate improved guidelines and to identify potential non-linear effects of overhead work height. Several indicators of shoulder fatigue served as outcome measures and a preliminary study was performed to assess the reliability of several of these measures. Fatigue measures based on electromyography (EMG) generally had low reliability, whereas excellent reliability was exhibited for ratings of perceived discomfort (RPD). Consistent with this, no effects of overhead work height were found on EMG-based measures, yet clear non-linear effects were found on RPD and task performance. The source of the effects of work height appeared to be related to a combination of muscle activation levels and demands on precision/control at the highest location. These results support the utility of subjective measures for relatively low-level intermittent exertions and demonstrate increasingly detrimental fatigue and performance effects at extremes in reach during overhead work.     

Effects of work experience on work methods during dynamic pushing and pulling

Pushing and pulling are potential risk factors for work-related low back disorders (WRLBDs). While several studies have evaluated differences in work methods related to work experience, such evidence for dynamic pushing and pulling is limited. Eight novices and eight experienced workers completed dynamic push/pull tasks using a cart weighted to 250% of individual body mass in two different configurations (preferred vs. elbow handle heights). Multiple measures [hand forces, torso kinematics and kinetics, and required coefficient of friction (RCOF)] were obtained to assess WRLBD and slip risks. Experienced workers generated higher medio-lateral hand forces, during both pulls and pushes, though with a more substantial difference during pushes (∼74%), and which involved the use of hand force components other than to move the cart in an anterior-posterior direction. Experienced workers also had lower peak torso kinematics in flexion/extension and lateral bending, and lower torso flexion/extension kinetics. The latter is suggestive of a lower risk for WRLBDs, though levels of exposures to WRLBD risk were low to moderate in both groups and were often relatively small and inconsistent across the task configurations. Group-level differences in RCOF were quite small, indicating a comparable slip risk between the two groups. Thus, it was considered inconclusive whether the work methods used by experienced workers during dynamic pushing and pulling are advantageous regarding WRLBD and slip risks.     

Risk factor model for suicide assessment and intervention.

Psychologists are faced with the challenge of how to apply the growing knowledge about suicide in their clinical practice. A practical and easy-to-use model for integrating this knowledge is proposed, one which psychologists can use to guide their suicide risk assessments and clinical decision making. This model is based on known risk factors for suicide that are categorized as historical, personal, psychosocial–environmental, and clinical and are dichotomized into acute and chronic states. The model includes protective factors that are categorized as temporary and permanent. An example of how to use this model in clinical practice is provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of circumferential pressure as an intervention to mitigate postural instability induced by localized muscle fatigue at the ankle

Pressure application via taping reportedly improves proprioception, and localized muscle fatigue (LMF) increases postural sway, which may be due to a loss of position sense acuity (PSA). This exploratory study investigated the effects of circumferential pressure (CP) and induced ankle LMF on sway. Fourteen young participants performed fatiguing sub-maximal isotonic plantarflexion exercises. Ankle PSA was determined, and used to categorize participants (i.e. high and low groups). Postural sway during quiet standing was assessed using a force platform, both pre- and post-LMF. CP was applied unilaterally to the dominant leg above the ankle joint. Both CP and LMF resulted in greater sway in the low PSA group. CP did not mitigate LMF effects on sway in the low PSA group, but reduced sway among the high PSA group. Reduced PSA may thus indicate less reliance on somatosensation for balance maintenance.

Relevance to industry

Potential benefits of circumferential pressure were indicated. Specifically, CP at the ankle led to improved postural control in certain individuals, which suggests that pressure application might thereby improve balance maintenance and help reduce occupational fall incidents. Results might help to design occupational interventions (specifically CP or taping) differently for individuals with low vs. high PSA.     

Estimation of forces exerted by the fingers using standardised surface electromyography from the forearm

Determination and integration of human force capabilities and requirements is an essential component of ergonomic evaluation. With regard to hand-intensive tasks, direct force measurements can be cumbersome and intrusive. Here, the use of surface electromyography (EMG) was evaluated. EMG was obtained from three standardised electrode sites on the forearms of 30 individuals. Linear regression models were generated to estimate finger force levels from normalised electromyographic measures, while forces were generated in several finger couplings. The results suggest that standardised procedures for obtaining electromyographic data and simple linear models can be used to accurately estimate finger forces during a variety of finger exertions in fixed postures, although the level of accuracy depends on the type of model. Such models begin to overcome the limitations of direct finger strength measurements of individuals.     

Expression of Aquaglyceroporins in Spermatozoa from Wild Ruminants Is Influenced by Photoperiod and Thyroxine Concentrations

This work identified the presence of AQPs in frozen-thawed sperm of wild ruminants and assessed the influence of the interaction between photoperiod and thyroxine on AQP expression, and on testosterone secretion. Thyroxine and melatonin were administered to ibexes. In a second experiment, performed in mouflons, circulating thyroxine was reduced via treatment with propylthiouracil (PTU), and an artificial long day (LD) photoperiod established. In the ibexes, the melatonin treatment increased the blood plasma testosterone concentration, reduced the cryoresistance ratio (CR) for sperm viability and the presence of an intact acrosome, and increased the percentage of sperm with AQP7 in the acrosome and of AQP3 and AQP10 in the midpiece. In the mouflons, neither the PTU treatment, the LD, nor the combination of both affected the CR of any sperm variable. The percentage of sperm with AQP3 increased in the post-acrosome region but decreased in the tail in the LD+PTU group. The percentage of sperm with AQP10 in the principal piece and endpiece was lower in the PTU+LD group than in the control and LD groups. The influence of photoperiod/melatonin on AQP expression might be indirectly exerted through changes in the testosterone concentration, and thus ultimately affect sperm cryoresistance.     

Capillary Force Lithography: Fabrication of Functional Polymer Templates as Versatile Tools for Nanolithography

The implementation of high‐resolution polymer templates fabricated by capillary force lithography (CFL) is explored both in nanoimprint lithography (NIL) and in the wet‐etching of metals. Several different thermoplastic and UV‐curable polymers and types of substrates are incorporated into the general CFL procedure to meet the diverging requirements of these two applications. The mechanical stability of UV‐curable templates for imprinting in polymers, as examined by atomic force microscopy (AFM), and their anti‐adhesive properties are excellent for application in NIL. The conditions for curing the UV‐curable polymer are optimized in order to obtain high‐stability polymer templates. Gold patterns on silicon with a lateral resolution of 150 nm are fabricated by subsequent lift‐off in acetone. Similar patterns with a lateral resolution of 100 nm are fabricated using templates of thermoplastic polymers on gold layers on silicon as an etch mask. The transfer of stamp residues during CFL with these polymer templates is proven by X‐ray photoelectron spectroscopy (XPS) and AFM friction analysis. For poly(methylmethacrylate) (PMMA), the presence of large amounts of silicon‐containing residues is found to compromise the processability of the resulting template in subsequent O₂ reactive‐ion etching (RIE) treatment. The extent of silicon contamination is up to six times less for polystyrene (PS). At this level, the etch performance of the PS etch mask is not affected, as was the case for PMMA. Accurate downscaling of the lateral dimensions of the resulting metal patterns by several factors with respect to the dimensions of the PS etch mask is achieved by over‐etching of the gold. Overall, the results in this paper demonstrate the potential of CFL templates as tools for high‐resolution soft lithography.     

产品剖析:驰骋于沙漠的无人驾驶汽车

Darpa Grand Challenge--自从各种传说中的横贯大陆的竞赛在一个世纪以前开始举办以来,从来没有哪一种令人生畏的工作能吸引如此多的工程师、教授、学生、企业团队以及汽车修理工参与其中.表面上看,它似乎是不可能被完成的.     

Development of a metric to assess the complexity of assembly/disassembly tasks in open architecture products

This paper describes two metrics to measure the complexity involved in assembly and disassembly tasks for open architecture products during its use phase. The approach proposed is based on the summary of all tasks required to assemble and disassemble a predefined set of modules to generate several product variants, which comprise different working levels or functionalities. The aim of the method is to provide a useful tool to designers in the analysis of product complexity regarding use and further phases in which the assembly and disassembly of modules are required. The benefits and usefulness of the metrics are oriented to enhance the sustainability performance of products through the measurement of complexity in modular systems for the decision-making during the design stage. The reduction of complexity involves significant benefits in all lifecycle phases of product, especially when the user or customer is responsible for many related tasks (maintenance, upgrading, reconfiguration and final disposal of modules). The metrics and their calculation process are illustrated using two case study products.     

Reducing injuries among Native Americans: five cost-outcome analyses

This paper presents cost-outcome analyses of five injury prevention efforts in Native American jurisdictions: a safety-belt program, a streetlight project, a livestock control project, a drowning prevention program, and a suicide prevention and intervention program. Pre- and post-intervention data were analyzed to estimate projects' impact on injury reduction. Projects' costs were amortized over the time period covered by the evaluation or over the useful life of physical capital invested. Projects' savings were calculated based on estimated reduction in medical and public program expenses, on estimated decrease in lost productivity, and on estimated quality adjusted life years saved.All projects yielded positive benefit-cost ratios. The net cost per quality adjusted life years was less than zero (i.e. the monetary savings exceeded project costs) for all but one of the projects.