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1.
Introduction. Few studies have addressed whether firefighters are fitter than the general population and possess sufficient levels of aerobic capacity and muscle strength to perform on-duty tasks in a safe and efficient manner, considering age and gender. We aimed to evaluate the fitness levels of Hamilton firefighters, and to determine the effects of age and gender. Methods. In total, 89 participants were recruited. The modified Canadian aerobic fitness test was used to determine participants’ estimated maximal oxygen consumption (VO2max) levels. For upper and lower body strength levels, a calibrated J-Tech hand-held dynamometer and a National Institute for Occupational Safety and Health (NIOSH) lifting device was used respectively. Results. Firefighters’ mean (SD) VO2max level was 40.30?±?6.25?ml·kg?1·min?1. Age proved to have a statistically significant impact on VO2max (p?<?0.001). Gender displayed statistically significant effects on strength levels. Firefighters’ age was the only statistically significant independent variable, and accounted for 61.00% of the variance in firefighters’ aerobic capacity levels. Conclusions. Firefighters possessed somewhat similar aerobic capacities but much higher levels of body strength when compared with the general population. With age, firefighters’ aerobic capacities decreased; however, their upper and lower body strength levels remained the same.  相似文献   

2.
Objective: Driver distraction and inattention are the main causes of accidents. The fact that devices such as navigation displays and media players are part of the distraction problem has led to the formulation of guidelines advocating various means for minimizing the visual distraction from such interfaces. However, although design guidelines and recommendations are followed, certain interface interactions, such as menu browsing, still require off-road visual attention that increases crash risk. In this article, we investigate whether adding sound to an in-vehicle user interface can provide the support necessary to create a significant reduction in glances toward a visual display when browsing menus.

Methods: Two sound concepts were developed and studied; spearcons (time-compressed speech sounds) and earcons (musical sounds). A simulator study was conducted in which 14 participants between the ages of 36 and 59 took part. Participants performed 6 different interface tasks while driving along a highway route. A 3 × 6 within-group factorial design was employed with sound (no sound /earcons/spearcons) and task (6 different task types) as factors. Eye glances and corresponding measures were recorded using a head-mounted eye tracker. Participants’ self-assessed driving performance was also collected after each task with a 10-point scale ranging from 1 = very bad to 10 = very good. Separate analyses of variance (ANOVAs) were conducted for different eye glance measures and self-rated driving performance.

Results: It was found that the added spearcon sounds significantly reduced total glance time as well as number of glances while retaining task time as compared to the baseline (= no sound) condition (total glance time M = 4.15 for spearcons vs. M = 7.56 for baseline, p =.03). The earcon sounds did not result in such distraction-reducing effects. Furthermore, participants ratings of their driving performance were statistically significantly higher in the spearcon conditions compared to the baseline and earcon conditions (M = 7.08 vs. M = 6.05 and M = 5.99 respectively, p =.035 and p =.002).

Conclusions: The spearcon sounds seem to efficiently reduce visual distraction, whereas the earcon sounds did not reduce distraction measures or increase subjective driving performance. An aspect that must be further investigated is how well spearcons and other types of auditory displays are accepted by drivers in general and how they work in real traffic.  相似文献   

3.
Aim. The purpose of this study was to examine the associations between various health and fitness measures and Functional Movement Screen? (FMS?) scores among 78 firefighter recruits. Methods. Relationships between FMS? scores and age, body mass index (BMI), sit and reach (S&R) distance, estimated maximal aerobic capacity (O2max), estimated one-repetition maximum squat (1RM-Squatmax), and plank endurance (%Plankmax) were examined. Results. Total FMS? scores were significantly correlated with BMI (r?=??0.231, p?=?0.042), estimated 1RM-Squatmax (r?=?0.302, p?=?0.007), and %Plankmax (r?=?0.320, p?=?0.004). Multiple regression analyses indicated that this combination of predictors significantly predicted (F(3, 74)?=?5.043, p?=?0.003) Total FMS? score outcomes and accounted for 17% of the total variance (R2?=?0.170). In addition, logistic regression analyses indicated that estimated 1RM-Squatmax also significantly predicted (χ2?=?6.662, df?=?1, p?=?0.010) FMS? group membership (≤14 or ≥15). Conclusion. These results suggest that the health and fitness measures of obesity (BMI), bilateral lower extremity strength (estimated 1RM-Squatmax), and core muscular endurance (%Plankmax) are significantly associated with functional movement patterns among firefighter recruits. Consequently, injury prevention programs implemented among firefighter recruits should target these aspects of health and fitness.  相似文献   

4.
Objectives: This study investigated the relationship between self-reported aberrant driving behaviors, mindfulness, and self-reported crashes and infringements.

Methods: Three hundred and eighteen participants (M = 46.0 years, SD = 13.7 years; female: 81.8%) completed an online survey that assessed aberrant driving behaviors, mindfulness (including regular mindfulness meditation [MM]), and self-reported crashes and infringements during the past 2 years. Structural equation modeling (SEM) was used to examine the relationship between self-reported aberrant driving behaviors and mindfulness simultaneously, as well as with participants' age and estimated kilometers driven over the past year.

Results: The results of the SEM showed that mindfulness was negatively related to each self-reported aberrant driving behavior, with the strongest relationships being between mindfulness and driving-related lapses (?0.58) and errors (?0.46). Participants who practice MM had significantly fewer crashes in the past 2 years and reported significantly fewer driving-related violations and lapses compared to participants who did not practice MM (crashes: 9.3% vs. 18.8%, P < .05; violations: M = 6.66 [SD = 3.44] vs. M = 7.68 [SD = 4.53], P < .05; errors: M = 5.17 [SD = 3.44] vs. M = 6.19 [SD = 4.12], P < .05).

Conclusions: More research is needed to understand whether MM results in more mindful and attentive drivers or whether individuals who practice MM may have other traits or behaviors that are linked to improved safety.  相似文献   

5.
The purpose of this study was to develop a relationship to evaluate the grip force (forcerel) using the electromyogram (EMGrel) of the flexor digitorum superficialis (FDS) and of the extensor digitorum (ED) according to the flexion-extension wrist angle (θf.e) and to the pronation-supination forearm angle (θp-s).

Fifteen participants had to exert 3 levels of grip forces in 4 positions of the wrist combined with 3 positions of the forearm.

The relationship is:

forcerel = 0.0045· θf-e· EMGrel(FDS) + 0.48· EMGrel(FDS)–0.0014 · θf-e · EMGrel(ED) –0.0016 · θp.s · EMGrel(ED) + 0.4· EMGrel(ED)

This relationship can be used to estimate grip force for levels of strength lower than 50% of the maximal voluntary contraction.  相似文献   

6.
IntroductionSeveral studies have concluded that pedestrians typically overestimate their own conspicuity to approaching drivers at night. The present experiments extended this research by exploring the accuracy of drivers' judgments of pedestrian conspicuity while facing varying degrees of headlight glare.MethodIn Experiment 1, participants on an open road estimated their ability to see a roadside pedestrian in each of two clothing configurations and with each of three different glare intensities present. In Experiment 2, participants responded to a roadside pedestrian under the same open road conditions; the participants were naïve with regard to both the position of the pedestrian and to the clothing and glare manipulations.ResultsConsistent with earlier research, estimates of response distance were, on the average, over three times greater than actual recognition distance. The extent to which participants overestimated conspicuity was greater when the pedestrian wore a retroreflective vest, and participants incorrectly judged that headlight glare would not degrade drivers' ability to see a pedestrian wearing a retroreflective vest.Conclusions and Practical ApplicationsThese results confirm that road users' understanding of issues involving drivers' night vision is limited. These misunderstandings may result in road users behaving in ways that increase the risk of nighttime collisions with pedestrians.  相似文献   

7.
Annual ryegrass (Lolium perenne L.) is an important cool-season forage grass in the southeastern US. Since large portions of soils in this region are too acidic for optimum ryegrass production, there exists an opportunity to use lime mud waste from numerous regional pulp and paper mills as an agricultural liming material. In this study, four lime mud application rates, 2.25 (L1), 4.51 (L2), 9.01 (L3), and 22.50 (L4) ton ha−1, dry weight basis, and a control (L0) were evaluated for response to ryegrass growth during the first 6 weeks to estimate an optimum application range over the testing soil for future field test. Results indicated that applied lime mud slowed ryegrass germination and seedling emergence, with differences of whole plant length among treatments L0–L4 significant only during the first three weeks. Differences of whole plant dry weight among treatments L0–L4 reduced thereafter. The initial soil pH increase due to the lime mud application dropped in treatments L1–L4 by the end of the 6-week experiment. The optimum lime mud application range was estimated between L2 and L3, which provided higher ryegrass yields (kg ha−1) of 84 and 80 over 77 of the control and complied with the Code of Federal Regulation, CFR 40 Part 503 for land application.  相似文献   

8.
Abstract

Objective: Fatal brain injuries result from physiological changes in brain tissues, subsequent to primary damage caused by head impact. Although efforts have been made in past studies to estimate the probability of brain injury, none of them involved prediction of such physiological changes. The goal of this study was to evaluate the fatality prediction capability of a novel approach that predicts an increase in intracranial pressure (ICP) due to primary head injury to estimate the fatality rate using clinical data that correlate ICP with fatality rate.

Methods: A total of 12 sets of head acceleration time histories were used to represent no, severe, and fatal brain injury. They were obtained from the literature presenting head kinematics data in noninjurious volunteer sled tests or from accident reconstruction for severe and fatal injury cases. These were first applied to a Global Human Body Models Consortium (GHBMC) head–brain model to predict nodal displacement time histories of the brain, which were then fed into FEBio to predict ICP. A Weibull distribution was applied to the data for the relationship between fatality rate and ICP obtained from a clinical paper to estimate fatality rate from ICP (procedure A). Fatality rate was also estimated by applying the temporal and spatial maximum value of maximum principal strain (MPSmax) obtained from the GHBMC simulation to an injury probability function for MPSmax (procedure B). Estimated fatality rates were compared between the 2 procedures.

Results: Both procedures estimated higher average fatality rate for higher injury severity. The average fatality rate for procedure A without ischemia representation and procedure B was 72.4 and 51.0% for the fatal injury group and 8.2 and 21.7% for the severe injury group, respectively, showing that procedure A provides more distinct classification between fatal and nonfatal brain injury. It was also found that representation of ischemia in procedure A provides results sensitive to injury severity and impact conditions, requiring further validation of the initial estimate for the relationship between brain compression and ischemic cell death.

Conclusions: Prediction of the probability of fatality by means of a combination of simulations of the primary brain deformation and subsequent ICP increase was found to be more distinct compared to the prediction of primary injury alone combined with the injury probability function from a past study in the select 12 head impact cases.  相似文献   

9.
Introduction: Employers engaged in similar business activities demonstrate a range of workers' compensation claim rates. Workplace injuries and illnesses could be prevented if employers with high claim rates achieved the claim rates of their safer peers. Methods: We used Washington workers' compensation claims data for years 2013–2015 to calculate rates of compensable claims (eligible for disability or time loss benefits, if unable to work four days after injury) and total accepted claims (compensable plus medical-aid only claims) for each employer. We estimated the number and cost of claims to occur if employers with high claim rates reduced them to the rates of employers at the 25th percentile, adjusted for insurance risk class, employer size, and injury type. To evaluate the impact of setting more or less ambitious goals, we also estimated reductions based on claim rates at the 10th and 50th percentiles. Results: Over 43% of claims and claim costs would be prevented if employers with higher claim rates lowered them to the 25th percentile using either total accepted or compensable claim rates as the benchmark outcome. The estimated claim cost savings from benchmarking to compensable claims was nearly as great as the estimate based on benchmarking to total accepted claims ($308.5 mil annually based on compensable claims vs. $332.4 mil based on total accepted claims). Restaurants and Taverns had the greatest number of potentially prevented compensable claims. Colleges and Universities and Wood Frame and Building Construction had the greatest potential reduction in compensable claim costs among larger and smaller employers, respectively. Conclusion: Substantial reductions in workers' compensation claims and costs are possible if employers achieve the injury rates experienced by their safer peers. Practical application: Evaluating the range of workplace injury rates among employers within industry groups identifies opportunities for injury prevention and offers another approach to resource allocation.  相似文献   

10.
This paper reports the results of flammability studies for methane, propane, hydrogen, and deuterium gases in air conducted by the Pittsburgh Research Laboratory. Knowledge of the explosion hazards of these gases is important to the coal mining industry and to other industries that produce or use flammable gases. The experimental research was conducted in 20 L and 120 L closed explosion chambers under both quiescent and turbulent conditions, using both electric spark and pyrotechnic ignition sources. The data reported here generally confirm the data of previous investigators, but they are more comprehensive than those reported previously. The results illustrate the complications associated with buoyancy, turbulence, selective diffusion, and ignitor strength versus chamber size. Although the lower flammable limits (LFLs) are well defined for methane (CH4) and propane (C3H8), the LFLs for hydrogen (H2) and its heavier isotope deuterium (D2) are much more dependent on the limit criterion chosen. A similar behavior is observed for the upper flammable limit of propane. The data presented include lower and upper flammable limits, maximum pressures, and maximum rates of pressure rise. The rates of pressure rise, even when normalized by the cube root of the chamber volume (V1/3), are shown to be sensitive to chamber size.  相似文献   

11.
The suitability of the IREQ (insulation required) index for predicting the thermal responses of 6 participants wearing chemical protective clothing was tested during exercise at -20 and -25 °C. IREQ was used to calculate duration limited exposure (DLE). Measured DLE correlated (r= .899, p < .001) with the predicted DLE. In exposures exceeding 40 min, however, the predicted DLE tended to be 10-20 min too short compared to the measured one. During short exposures the prediction was 5-20 min too long. The results show that IREQ overestimated the cold strain in participants wearing chemical protective clothing during cold exposures longer than 40 min. Nevertheless, predicted DLE never exceeded measured times and thus the prediction was always safe from the occupational point of view.  相似文献   

12.
The aim of this study was to investigate the synergistic effects of physical demands and shift working on low back disorders (LBDs) among nursing personnel. The study used 2 questionnaires: a self-administered questionnaire composed of parts of Nordic musculoskeletal questionnaire to assess LBDs and job content questionnaire to assess physical demands. The participants were divided into 4 groups: from group 1 (low physical demands day workers) to group 4 (high physical demands shift workers). In regression analysis, high physical demands were associated with the prevalence of LBDs independently (OR 4.4, 95% CI [2.40, 8.00] and p < .05), but there was no association between shift working and LBDs (p > .05). Odds ratio in high physical demands shift workers was 9.33 compared to the reference group (p < .001). Calculated synergistic index was 7.37. Simultaneous impacts of shift working and high physical demands may increase the prevalence of LBDs among nursing personnel.  相似文献   

13.
One of the most important points in the design of inherently safe processes is to estimate reliable distances among process units at preliminary stages of the plant project to minimize losses and damages caused by the potential occurrence of technological accidents. Therefore, in this paper the achievement of simple, general, dimensionless and reliable equations (Simple Dimensionless Models SDMs) for the direct estimation of safety distances considering the occurrence of BLEVE (Boiling Liquid Expanding Vapour Explosion) event, is proposed. The developed models directly relate safety distances with critical design/operation variables (involved substance, vessel volume, target vulnerability and explosion temperature), which are easily accessible at early stages of the plant project. SDMs are achieved by analysing the influence of these simple variables on the safety distances, which are estimated using a selected rigorous model (Reference Model RfM). This task is simplified by the incorporation of the Jakob Number as an input variable, allowing to obtain dimensionless models and simultaneously an adequate representation of the explosion conditions and the involved substances. As result, the achieved SDMs demonstrate a particularly good fit with respect to the RfM estimations and, at the same time, reliability and versatility. As it is shown in the analysed study cases (involving critical decision variables for the process design and the system safety), the SDMs prove to be also accurate, general, and easily incorporable into more complex optimization problems (QRA analysis, design of emergency plans, safety distance estimation to minimize the probability of domino effects, optimal layout designs, among others).  相似文献   

14.
Laboratory experiments were conducted to investigate carbon monoxide (CO) and carbon dioxide (CO2) emissions from spontaneous heating of three U.S. coal samples in an isothermal oven at temperatures between 50 and 110 °C. The oxygen (O2) concentration of an oxygen/nitrogen (N2) mixture flowing through the coal sample was 3, 5, 10, 15, and 21%, respectively. The temperature at the center of the coal sample was continuously monitored, while the CO, CO2, and O2 concentrations of the exit gas were continuously measured. The results indicate that the CO and CO2 concentrations and the CO/CO2 ratio increased when the initial temperature was increased. As the inlet O2 concentration increased, the CO and CO2 concentrations increased, while the CO/CO2 ratios tended to converge to the same value. The ratio of CO/CO2 was found to be independent of coal properties, approaching a constant value of 0.2. The maximum CO production rate correlated well with the maximum coal temperature rise. The apparent order of reaction for coal oxidation was estimated to be between 0.52 and 0.72. The experimental results in this study could be used for early detection and evaluation of a spontaneous heating in underground coal mines.  相似文献   

15.
Introduction: Limited research associated with safety climate has been completed within the fire service. Given this dearth of information, the present study sought to identify a valid and reliable measure of safety climate at both the workgroup and organizational levels within the fire service. Methods: Researchers surveyed 994 firefighters in two large metropolitan fire departments. Preliminary analyses including psychometrics, confirmatory factor analyses, and shared perception analyses were completed. A linear mixed model analysis was then completed to assess the relationships between workgroup safety climate, organizational safety climate, and safety behaviors, including both safety compliance and safety citizenship behaviors. Results: Measures of safety climate at the workgroup (WGSC) and organizational levels (OSC) were derived. WGSC factors include supervisor support (α = 0.92), vertical cohesion (α = 0.89), and horizontal cohesion (α = 0.94). OSC factors include management commitment (α = 0.91), safety programs/policies (α = 0.89), perceived fairness (α = 0.86) and incident command (α = 0.90). Confirmatory factor analyses confirmed our multi-factor models were a good fit to the data. The linear mixed model analysis found that WGSC positively predicted safety compliance behavior (B = 0.13, p < .001) and safety citizenship behavior (B = 0.22, p < .001) and OSC positively predicted safety compliance behavior (B = 0.16, p < .001) and safety citizenship behavior (B = 0.15, p < .001). Conclusions: This work presents reliable and valid measures of both workgroup and organizational safety climate, which have positive relationships with safety behavior outcomes. Practical application: The measures, which were developed through an extensive multi-method process, provide a means for researchers and practitioners to assess safety climate in the fire service and provides guidance for future safety climate research, including informing intervention research, which could potentially bolster safety climate and enhance safety in the fire service.  相似文献   

16.
The purpose of this study was to compare the effects of 2 kinds of underwear made from hydrophobic and hydrophilic fabrics on the mean skin temperatures and clothing microclimate (temperature, humidity) in participants performing intermittent exercise in cold environmental conditions.

One or 2 layers of cotton underwear (C1, C2) with a 2-piece long-sleeved shirt and long-legged trousers, and 1 or 2 layers of polypropylene underwear (P1, P2) with a 2-piece long-sleeved shirt and long-legged trousers were used as experimental underwear. In addition, the participants wore a 2-piece ski suit as 100% polyester clothing including 100% polyester padding. Ten young adult females volunteered as participants. The experiments were performed in a climatic chamber at an ambient temperature (Ta) of 0°C and an air velocity of 0.26 m s?1.

The major findings are summarized as follows: (a) Although the clothing microclimate humidity was not different within the ski suit of outer clothing between C1 and P1, it was significantly higher in P2 than in C2; (b) Clothing microclimate temperature inside the ski suit did not differ between C1 and P1, whereas it was significantly higher in P2 than in C2; (c) The thermal gradient between innermost and outermost of clothing microclimate at back level did not show any difference between C1 and P1, but it was significantly higher in C2 than in P2. These results are discussed in terms of thermal physiology and clothing sciences.  相似文献   

17.
Results of standard pure-tone audiometry (PTA) were collected from 25 workers, mainly females, aged 23-58 years, exposed for 2-13 years to ultrasonic noise emitted by ultrasonic welders. Hearing tests were completed by evaluation of exposure to ultrasonic noise. The subjects' actual audiometric hearing threshold levels (HTLs) were compared with theoretical predictions calculated according to ISO 1999:1990. In 60% of cases sound pressure levels in the 10-40 kHz 1/3-octave bands at workstands exceeded Polish exposure limits for ultrasonic noise. Our comparison of predicted and measured HTLs suggests that the ISO 1999:1990 method, intended for audible noise, might also make it possible to predict reliably permanent hearing loss (in the 2000-6000 Hz frequency range) after exposure to ultrasonic noise. No significant progress of hearing impairment (assessed using PTA) in the operators of ultrasonic welders was noted. Nevertheless, further studies on the hearing status of workers exposed to ultrasonic noise are needed.  相似文献   

18.
The corrosion rates of API X65 mild steel alloy in CO2 – containing produced water have been studied by weight loss technique, potentiodynamic polarization technique and characterization of the corroded surface techniques. The effect of temperature, speed of rotation, pH and acetic acid concentration were studied. The optimum condition in presence and absence of protective film were also addressed. The kinetic parameters and reaction behavior were discussed in details. Corrosion rates increases with increasing temperature, acetic acid concentration, and speed of rotation, and decreased with increasing solution pH. The primary corrosion product of API X65 mild steel is ferrous carbonate (FeCO3) at high temperatures, high pH's (alkaline media) and absence of acetic acid, which could act as a protective film so that CO2 corrosion rate can be reduced.  相似文献   

19.
Two-phase CFD (Computational Fluid Dynamics) model for characterising the spill-over/dispersion of peroxy-fuels is presented. The model is independent of type and burning rate of the spilled/dispersed fuel and considers only overflow Reynolds number (Re) to characterise the spill/dispersion behaviour. Additional simulations are performed for LNG (Liquified Natural Gas) dispersion and it is found that the model can be used for different fuels within a defined range of Re. Different scenarios with Re = 100 to 3 × 105 are investigated covering a wide range of mass flow rates, opening sizes and viscosities. Depending on Lower Flammability Limits (LFL) of the fuels spill/dispersion (vapour cloud) diameters (DCFD) and heights (hCFD) are predicted. A generalised correlation between DCFD and Re is established to predict the dispersion occurring at varying scales. The model is validated by: (1) conducting an extensive grid independent study; (2) comparing the results with the existing analytical methods and (3) comparing against the standard field test data on LNG dispersions.  相似文献   

20.
This study aims to develop a quantitative risk assessment (QRA) framework for on-board hydrogen storage systems in light-duty fuel cell vehicles, with focus on hazards from potential vehicular collision affecting hydride-based hydrogen storage vessels. Sodium aluminum hydride (NaAlH4) has been selected as a representative reversible hydride for hydrogen storage. Functionality of QRA framework is demonstrated by presenting a case study of a postulated vehicle collision (VC) involving the onboard hydrogen storage system. An event tree (ET) model is developed for VC as the accident initiating event. For illustrative purposes, a detailed FT model is developed for hydride dust cloud explosion as part of the accident progress. Phenomenologically-driven ET branch probabilities are estimated based on an experimental program performed for this purpose. Safety-critical basic events (BE) in the FT model are determined using conventional risk importance measures. The Latin Hypercube sampling (LHS) technique has been employed to propagate the aleatory (i.e., stochastic) and epistemic (i.e., phenomenological) uncertainties associated with the probabilistic ET and FT models. Extrapolation of the proposed QRA framework and its core risk-informed insights to other candidate on-board reversible and off-board regenerable hydrogen storage systems could provide better understanding of risk consequences and mitigation options associated with employing this hydrogen-based technology in the transportation sector.  相似文献   

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