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- Halder, Amitava, et al.
(författare)
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Gait Biomechanics While Walking Down an Incline After Exhaustion
- 2023
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Ingår i: Fire Technology. - 1572-8099. ; 59:4, s. 1833-1863
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Tidskriftsartikel (refereegranskat)abstract
- This gait biomechanics study investigated stride length (SL), stride duration (SDN), the peak values of ground reaction forces (GRFspeak), required coefficient of friction (RCOFpeak), leg joints’ angles (anglepeak), angular velocity (angvelx.peak), angular acceleration (angaccx.peak), minimum angle (anglemin.) of the foot, and muscles’ electromyography (EMG) during the stance phase (SP) of the dominant leg following an exhaustive stair ascent on a stair machine. Data were collected by a three-dimensional motion capture system synchronized with EMG and force plate while walking down a 10° inclined stationary walkway. Although the leg muscles’ EMG showed no significant local muscle fatigue (LMF) during post-exhaustive walking downwards, the SL was significantly (p < 0.05) shorter than the pre-exhaustive. The mean vertical GRFzpeak. was significantly (p ≤.01) reduced during late stance (LS) phase, however, the antero-posterior GRFypeak. was found to be significantly (p ≤ 0.01) higher. The RCOFpeak. was significantly (p ≤.05) higher during the post-exhaustive walking downwards, LS phase. The available coefficient of friction value of ~ 0.350 seems to be the RCOF to reduce slips and falls on an inclined dry surface. None of the post-exhaustive lower limb joints’ anglepeak, anglemin., ang.velx.peak, and ang.accx.peak were significantly changed in post-exhaustion walking, except the knee ang.accx.peak., which was significantly (p < 0.05) increased during the LS period. The constrained post-exhaustive gait biomechanics indicate a perturbed gait, which may increase the risks for slips and fall-related accidents, when walking downwards and working on slopes. However, the non-significant joint angle changes imply that walking down is less demanding in a kinesiological perspective compared to walking up an incline.
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- Halder, Amitava, et al.
(författare)
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Limitations of oxygen uptake and leg muscle activity during ascending evacuation in stairways
- 2017
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Ingår i: Applied Ergonomics. - : Elsevier BV. - 0003-6870. ; 66, s. 52-63
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Tidskriftsartikel (refereegranskat)abstract
- Stair ascending performance is critical during evacuation from buildings and underground infrastructures. Healthy subjects performed self-paced ascent in three settings: 13 floor building, 31 floor building, 33 m stationary subway escalator. To investigate leg muscle and cardiorespiratory capacities and how they constrain performance, oxygen uptake (VO2), heart rate (HR) and ascending speed were measured in all three; electromyography (EMG) in the first two. The VO2 and HR ranged from 89-96 % of the maximum capacity reported in the literature. The average highest VO2 and HR ranged from 39-41 mL·kg-1·min-1 and 162-174 b·min-1, respectively. The subjects were able to sustain their initial preferred maximum pace for a short duration, while the average step rate was 92-95 steps·min-1. In average, VO2 reached relatively stable values at ≈37 mL·kg-1·min-1. EMG amplitudes decreased significantly and frequencies were unchanged. Speed reductions indicate that climbing capacity declined in the process of fatigue development. In the two buildings, the reduction of muscle power allowed the subjects to extend their tolerance and complete ascents in the 48 m and 109 m high stairways in 2.9 and 7.8 minutes, respectively. Muscle activity interpretation squares were developed and proved advantageous to observe fatigue and recovery over time.
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- Ioannou, Leonidas G., et al.
(författare)
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Occupational heat stress : Multi-country observations and interventions
- 2021
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1661-7827 .- 1660-4601. ; 18:12
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Tidskriftsartikel (refereegranskat)abstract
- Background: Occupational heat exposure can provoke health problems that increase the risk of certain diseases and affect workers’ ability to maintain healthy and productive lives. This study investigates the effects of occupational heat stress on workers’ physiological strain and labor productivity, as well as examining multiple interventions to mitigate the problem. Methods: We monitored 518 full work-shifts obtained from 238 experienced and acclimatized individuals who work in key industrial sectors located in Cyprus, Greece, Qatar, and Spain. Continuous core body temperature, mean skin temperature, heart rate, and labor productivity were collected from the beginning to the end of all work-shifts. Results: In workplaces where self-pacing is not feasible or very limited, we found that occupational heat stress is associated with the heat strain experienced by workers. Strategies focusing on hydration, work-rest cycles, and ventilated clothing were able to mitigate the physiological heat strain experienced by workers. Increasing mechanization enhanced labor productivity without increasing workers’ physiological strain. Conclusions: Empowering la-borers to self-pace is the basis of heat mitigation, while tailored strategies focusing on hydration, work-rest cycles, ventilated garments, and mechanization can further reduce the physiological heat strain experienced by workers under certain conditions.
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- Zhao, Mengmeng, et al.
(författare)
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Effects of Two Cooling Garments on Post-exercise Thermal Comfort of Female Subjects in the Heat
- 2015
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Ingår i: Fibers and Polymers. - : Springer Science and Business Media LLC. - 1229-9197 .- 1875-0052. ; 16:6, s. 1403-1409
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the study was to investigate and compare the effect of two cooling garments with phase change material (PCM) and ventilation on thermal comfort. Eight female university students (age 24±1 years; height 162±4 cm; body weight 54±4 kg) exercised on a treadmill in an environment of 32 oC with 50 % relative humidity. Tests in three conditions were carried out after moderate exercise with t-shirt and shorts: cooling with a PCM vest (PCM); cooling with a ventilation jacket (VEN) and without cooling clothing (natural cooling, a control condition, CON). Results showed that no significant differences were observed in the mean skin temperature and heart rate among the two cooling garment conditions and the control condition (p>0.05). The local torso skin temperature was observed with significant difference among the three conditions (p<0.05) and it was mostly reduced by 0.7 oC and 0.9 oC, respectively in PCM and VEN. Significant differences were observed in the clothing torso micro-climate temperature and humidity among the three testing scenarios (p<0.05). The clothing micro-climate temperature was dropped by 2 oC in PCM and 0.8 oC in VEN. The clothing micro-climate humidity in PCM was 40 % higher than that in VEN after 30 minutes cooling. The perceived thermal sensation was the lowest in PCM whereas the perceived skin wettedness sensation was the lowest in VEN.
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- Pedersen, Eja, et al.
(författare)
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Tenant perceptions of post-renovation indoor environmental quality in rental housing: improved for some, but not for those reporting health-related symptoms
- 2020
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Ingår i: Building and Environment. - : Elsevier BV. - 1873-684X .- 0360-1323. ; 189
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Tidskriftsartikel (refereegranskat)abstract
- Much of the 1950–1970s building stock in Sweden and other European countries is being renovated to reduce energy use and for general upgrading. To realize the UN Sustainable Development Goals, the renovations should also improve indoor environmental quality (IEQ). The PEIRE (People-Environment-Indoor-Renovation-Energy) study followed the renovation of a multifamily housing area in Sweden comprising 14 buildings with 323 dwellings in total. We aimed to investigate tenant perception of IEQ changes after the renovation with focus on perceived control of IEQ, recalling of being informed how to control IEQ, and if tenants with self-reported symptoms perceive the changes differently. A post-renovation survey (n = 104, response rate 36%) showed that the renovation increased the proportion of residents experiencing satisfactory thermal comfort and air quality in the winter, as well as improved noise conditions. Perceiving reduced draught in the thermal environment was associated with experiencing being informed and being able to control heat and ventilation. Respondents reporting skin irritation symptoms were less likely than others to perceive any improvements of IEQ factors such as air quality, daylight, noise from installations and neighbours, and periods of excessive heat. Renovations targeting housing sustainability – here, decreasing energy use and mitigating wear and tear while keeping the rents low – could increase tenant perceptions of improved IEQ, especially if factors concerning information and tenants’ ability to control the regulating systems are addressed. Interestingly, results of this study point out that tenants experiencing IEQ-related symptoms may require enhanced IEQ improvements to experience the renovation as satisfactory.
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- Adams, Nicholas, et al.
(författare)
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El Niño Southern Oscillation, monsoon anomaly, and childhood diarrheal disease morbidity in Nepal
- 2022
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Ingår i: PNAS Nexus. - : Oxford University Press (OUP). - 2752-6542. ; 1:2
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Tidskriftsartikel (refereegranskat)abstract
- Climate change is adversely impacting the burden of diarrheal diseases. Despite significant reduction in global prevalence, diarrheal disease remains a leading cause of morbidity and mortality among young children in low- and middle-income countries. Previous studies have shown that diarrheal disease is associated with meteorological conditions but the role of large-scale climate phenomena such as El Niño-Southern Oscillation (ENSO) and monsoon anomaly is less understood. We obtained 13 years (2002–2014) of diarrheal disease data from Nepal and investigated how the disease rate is associated with phases of ENSO (El Niño, La Niña, vs. ENSO neutral) monsoon rainfall anomaly (below normal, above normal, vs. normal), and changes in timing of monsoon onset, and withdrawal (early, late, vs. normal). Monsoon season was associated with a 21% increase in diarrheal disease rates (Incident Rate Ratios [IRR]: 1.21; 95% CI: 1.16–1.27). El Niño was associated with an 8% reduction in risk while the La Niña was associated with a 32% increase in under-5 diarrheal disease rates. Likewise, higher-than-normal monsoon rainfall was associated with increased rates of diarrheal disease, with considerably higher rates observed in the mountain region (IRR 1.51, 95% CI: 1.19–1.92). Our findings suggest that under-5 diarrheal disease burden in Nepal is significantly influenced by ENSO and changes in seasonal monsoon dynamics. Since both ENSO phases and monsoon can be predicted with considerably longer lead time compared to weather, our findings will pave the way for the development of more effective early warning systems for climate sensitive infectious diseases.
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