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Taggart SM, Girard O, Landers GJ, Ecker UKH, Wallman KE. A seasonal comparison of a 14-day swing on cognitive function and psycho-physiological responses in mine service workers. Appl Ergon 2024; 117:104241. [PMID: 38354553 DOI: 10.1016/j.apergo.2024.104241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 12/30/2023] [Accepted: 01/22/2024] [Indexed: 02/16/2024]
Abstract
This study assessed the effect of season on cognitive function and psycho-physiological responses during a 14-day swing in mine-service workers. Cognitive function, thermal sensation and comfort, rating of perceived exertion, fatigue, hydration, core temperature and heart rate were assessed throughout a shift, on three separate days over a swing. Working memory and processing efficiency did not differ between seasons (p > 0.05), however counting and recall latencies improved throughout the swing (p < 0.05). Participants reported greater fatigue post-shift compared to pre-shift (p < 0.05). Thermal sensation, thermal comfort, and hydration were significantly elevated in summer compared to winter (p < 0.05). Specifically, workers were significantly/minimally dehydrated in summer/winter (urinary specific gravity = 1.025 ± 0.007/1.018 ± 0.007). Although cognitive function and thermal strain were not impaired in summer compared to winter, it is essential to reinforce worker's knowledge regarding hydration requirements. Additional education and/or incorporating scheduled rest breaks for hydration should be considered to ensure the health and safety of mine workers.
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Affiliation(s)
- Sarah M Taggart
- School of Human Sciences (Sport Science, Exercise and Health), The University of Western Australia, Crawley, WA 6009, Australia.
| | - Olivier Girard
- School of Human Sciences (Sport Science, Exercise and Health), The University of Western Australia, Crawley, WA 6009, Australia
| | - Grant J Landers
- School of Human Sciences (Sport Science, Exercise and Health), The University of Western Australia, Crawley, WA 6009, Australia
| | - Ullrich K H Ecker
- School of Psychological Science, The University of Western Australia, Crawley, WA 6009, Australia
| | - Karen E Wallman
- School of Human Sciences (Sport Science, Exercise and Health), The University of Western Australia, Crawley, WA 6009, Australia
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Gordon RJFH, Moss JN, Castelli F, Reeve T, Diss CE, Tyler CJ, Tillin NA. Heat acclimation reduces the effects of whole-body hyperthermia on knee-extensor relaxation rate, but does not affect voluntary torque production. Eur J Appl Physiol 2023; 123:1067-1080. [PMID: 36637508 PMCID: PMC10119217 DOI: 10.1007/s00421-022-05127-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 12/23/2022] [Indexed: 01/14/2023]
Abstract
PURPOSE This study investigated the effects of acute hyperthermia and heat acclimation (HA) on maximal and rapid voluntary torque production, and their neuromuscular determinants. METHODS Ten participants completed 10 days of isothermic HA (50 °C, 50% rh) and had their knee-extensor neuromuscular function assessed in normothermic and hyperthermic conditions, pre-, after 5 and after 10 days of HA. Electrically evoked twitch and octet (300 Hz) contractions were delivered at rest. Maximum voluntary torque (MVT), surface electromyography (EMG) normalised to maximal M-wave, and voluntary activation (VA) were assessed during brief maximal isometric voluntary contractions. Rate of torque development (RTD) and normalised EMG were measured during rapid voluntary contractions. RESULTS Acute hyperthermia reduced neural drive (EMG at MVT and during rapid voluntary contractions; P < 0.05), increased evoked torques (P < 0.05), and shortened contraction and relaxation rates (P < 0.05). HA lowered resting rectal temperature and heart rate after 10 days (P < 0.05), and increased sweating rate after 5 and 10 days (P < 0.05), no differences were observed between 5 and 10 days. The hyperthermia-induced reduction in twitch half-relaxation was attenuated after 5 and 10 days of HA, but there were no other effects on neuromuscular function either in normothermic or hyperthermic conditions. CONCLUSION HA-induced favourable adaptations to the heat after 5 and 10 days of exposure, but there was no measurable benefit on voluntary neuromuscular function in normothermic or hyperthermic conditions. HA did reduce the hyperthermic-induced reduction in twitch half-relaxation time, which may benefit twitch force summation and thus help preserve voluntary torque in hot environmental conditions.
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Affiliation(s)
- Ralph Joseph Frederick Hills Gordon
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK. .,Faculty of Science and Engineering, School of Psychology & Sport Science, Anglia Ruskin University, East Road, Cambridge, CB1 1PT, UK.
| | - Jodie Natasha Moss
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK
| | - Federico Castelli
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK
| | - Thomas Reeve
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK
| | - Ceri Elen Diss
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK
| | - Christopher James Tyler
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK
| | - Neale Anthony Tillin
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK
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Deming NJ, Anna JL, Colon-Bonet BM, Dinenno FA, Richards JC. Carbohydrate ingestion attenuates cognitive dysfunction following long-duration exercise in the heat in humans. J Therm Biol 2021; 100:103026. [PMID: 34503773 DOI: 10.1016/j.jtherbio.2021.103026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 11/30/2022]
Abstract
INTRODUCTION To determine if electrolyte or carbohydrate supplementation vs. water would limit the magnitude of dehydration and decline in cognitive function in humans following long-duration hyperthermic-exercise. METHODS 24 subjects performed 3 visits of 2 h walking (3mph/7% grade) in an environmental chamber (33 °C/10% relative humidity). In random order, subjects consumed water (W), electrolytes (Gatorade Zero; E), or electrolytes+carbohydrates (Gatorade; E+C). Throughout exercise (EX), subjects carried a 23 kg pack and drank ad-libitum. Pre-and post-EX, body mass (BM) and plasma osmolality (pOsm) were measured. Physiological Strain Index (PSI) and core temperature (TC) were recorded every 15 min. Plasma glucose (GLU) was measured every 30 min. Cognitive processing (SCWT) was measured post-EX and compared to baseline (BL). A subset of 8 subjects performed a normothermic (N) protocol (21 °C/ambient humidity) to ascertain how the exercise stimulus influenced hydration status and cognition without heat. RESULTS There were no significant differences between fluid conditions (W, E, E+C) for BM loss (Δ2.5 ± 0.2, 2.5 ± 0.2, 2.3 ± 0.2 kg), fluid consumption (1.9 ± 0.2, 1.9 ± 0.2, 1.8 ± 0.2L), pOsm (Δ1.5 ± 2.7, 2.2 ± 2.4, 2.0 ± 1.5 mmol/L), peak-PSI (7.5 ± 0.4, 7.0 ± 0.6, 7.9 ± 0.5), and peak-TC (38.7 ± 0.1, 38.6 ± 0.2, 38.8 ± 0.2 °C). GLU decreased significantly in W and E, whereas it increased above BL in E+C at 60, 90, and 120 min (P < 0.05). Compared to BL values (43.6 ± 26 ms), SCWT performance significantly decreased in all conditions (463 ± 93, 422 ± 83, 140 ± 52 ms, P < 0.05). Importantly, compared to W and E, the impairment in SCWT was significantly attenuated in E+C (P < 0.05). As expected, when compared to the heat-stress protocol (W, E, E+C), N resulted in lower BM loss, fluid consumption, and peak-PSI (1.1 ± 0.1 kg, 1.2 ± 0.7L, 4.8, respectively), and improved SCWT performance. CONCLUSIONS These data are the first to suggest that, independent of supplementation variety, cognitive processing significantly decreases immediately following long-duration exercise in the heat in healthy humans. Compared to water and fluids supplemented with only electrolytes, fluids supplemented with carbohydrates significantly blunts this decrease in cognitive function.
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Affiliation(s)
- Nathan J Deming
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA; Air Force Institute of Technology, Wright-Patterson Air Force Base, OH, 45433, USA
| | - Jacob L Anna
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA
| | - Benjamin M Colon-Bonet
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA
| | - Frank A Dinenno
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA
| | - Jennifer C Richards
- Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA.
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Maley MJ, Minett GM, Bach AJE, Stewart KL, Stewart IB. Extending work tolerance time in the heat in protective ensembles with pre- and per-cooling methods. Appl Ergon 2020; 85:103064. [PMID: 32174352 DOI: 10.1016/j.apergo.2020.103064] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 01/16/2020] [Accepted: 01/27/2020] [Indexed: 05/28/2023]
Abstract
OBJECTIVES Investigate whether a range of cooling methods can extend tolerance time and/or reduce physiological strain in those working in the heat dressed in a Class 2 chemical, biological, radiological, nuclear (CBRN) protective ensemble. METHODS Eight males wore a Class 2 CBRN ensemble and walked for a maximum of 120 min at 35 °C, 50% relative humidity. In a randomised order, participants completed the trial with no cooling and four cooling protocols: 1) ice-based cooling vest (IV), 2) a non-ice-based cooling vest (PCM), 3) ice slushy consumed before work, combined with IV (SLIV) and 4) a portable battery-operated water-perfused suit (WPS). Mean with 95% confidence intervals are presented. RESULTS Tolerance time was extended in PCM (46 [36, 56] min, P = 0.018), SLIV (56 [46, 67] min, P < 0.001) and WPS (62 [53, 70] min, P < 0.001), compared with control (39 [30, 48] min). Tolerance time was longer in SLIV and WPS compared with both IV (48 [39, 58 min]) and PCM (P ≤ 0.011). After 20 min of work, HR was lower in SLIV (121 [105, 136] beats·min-1), WPS (117 [101, 133] beats·min-1) and IV (130 [116, 143] beats·min-1) compared with control (137 [120, 155] beats·min-1) (all P < 0.001). PCM (133 [116, 151] beats·min-1) did not differ from control. CONCLUSION All cooling methods, except PCM, utilised in the present study reduced cardiovascular strain, while SLIV and WPS are most likely to extend tolerance time for those working in the heat dressed in a Class 2 CBRN ensemble.
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Affiliation(s)
- Matthew J Maley
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Australia; Department of Sport, Institute of Human Sciences, University of Wolverhampton, Walsall, UK.
| | - Geoffrey M Minett
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Australia
| | - Aaron J E Bach
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Australia
| | - Kelly L Stewart
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Australia
| | - Ian B Stewart
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Australia
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TOKIZAWA K, SON SY, OKA T, YASUDA A. Effectiveness of a field-type liquid cooling vest for reducing heat strain while wearing protective clothing. Ind Health 2020; 58:63-71. [PMID: 31406053 PMCID: PMC6997718 DOI: 10.2486/indhealth.2018-0182] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 06/25/2019] [Indexed: 05/27/2023]
Abstract
This study examined the effectiveness of a field-type liquid cooling vest (LCV) worn underneath an impermeable protective suit on heat strain during walking. Eight men walked for 60 min at a moderate speed (3.0 km/h) wearing the suit in a warm environment (33°C, 60% relative humidity) without (control, CON) or with the LCV. A smaller increase in rectal temperature was recorded in participants in the LCV than in the CON condition (37.6 ± 0.1°C vs. 37.9 ± 0.1°C, p<0.05). Walking while wearing the LCV reduced the level of physiological heat strain, as measured by the mean skin temperature (35.5 ± 0.1°C vs. 36.3 ± 0.1°C), chest sweat rate (13.5 ± 3.0 mg/cm2/h vs. 16.6 ± 3.8 mg/cm2/h), chest cutaneous vascular conductance (349 ± 88% vs. 463 ± 122%), body weight loss (0.72 ± 0.05% vs. 0.93 ± 0.06%), and heart rate (101 ± 6 beats/min vs. 111 ± 7 beats/min) (p<0.05, for all comparisons). These changes were accompanied by a decrease in thermal sensation and discomfort. These results suggest that a field-type LCV attenuates exertional heat strain while wearing impermeable protective clothing.
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Affiliation(s)
- Ken TOKIZAWA
- National Institute of Occupational Safety and Health,
Japan
| | - Su-Young SON
- National Institute of Occupational Safety and Health,
Japan
- Present address: Kyungpook National University, Korea
| | - Tatsuo OKA
- National Institute of Occupational Safety and Health,
Japan
| | - Akinori YASUDA
- National Institute of Occupational Safety and Health,
Japan
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English T, Mavros Y, Jay O. Listening to motivational music mitigates heat-related reductions in exercise performance. Physiol Behav 2019; 208:112567. [PMID: 31173785 DOI: 10.1016/j.physbeh.2019.112567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 05/22/2019] [Accepted: 06/03/2019] [Indexed: 11/26/2022]
Abstract
PURPOSE To examine whether listening to motivational music mitigates heat-related reductions in exercise performance, and leads to a greater increase in thermal and cardiovascular strain. METHODS Twelve participants (26 ± 5 y, 77.5 ± 17.0 kg, 49 ± 8 ml·min-1·kg-1) completed 30-min of cycling preload at 50% VO2max followed by a 5-min rest and 15-min cycling time trial on seven separate occasions; three familiarisation sessions in a 20 °C room and four experimental trials in a climatic chamber regulated at either 21 °C, 50%RH (NEU) or 36 °C, 50%RH (HOT), each with and without the participant listening to self-selected motivational music during the 5-min rest and 15-min time trial. Measures of total work, core temperature and heart rate and blood pressure (from which rate-pressure product for cardiovascular strain was calculated), were recorded. RESULTS Without music, total work was lower (p < .001) in the HOT condition (168 ± 59 kJ) relative to the NEU condition (193 ± 60 kJ). With music, total work was greater relative to no music in both the NEU condition (203 ± 60 kJ vs 193 ± 60 kJ; p = .008) and HOT condition (183 ± 63 kJ vs 168 ± 60 kJ; p = .029). The greater total work in the HOT condition with music relative to no music resulted in a higher (p = .006) core temperature (38.7 ± 0.4 °C vs 38.6 ± 0.5 °C) and a higher (p < .001) rate-pressure product (34.8 ± 7.1 mmHg·beats·min-1·10-3 vs 27.8 ± 3.7 mmHg·beats·min-1·10-3). CONCLUSION Listening to motivational music mitigated heat-related reductions in exercise performance with an improvement in performance in the heat of ~10%. This improved exercise performance led to a greater increase in thermal and cardiovascular strain in the heat but did not exceed levels typically associated with an elevated health risk in a young, healthy population.
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Affiliation(s)
- Timothy English
- The University of Sydney, Thermal Ergonomics Laboratory, Faculty of Health Sciences, NSW, Australia; The University of Sydney, Charles Perkins Centre, NSW, Australia
| | - Yorgi Mavros
- The University of Sydney, Thermal Ergonomics Laboratory, Faculty of Health Sciences, NSW, Australia; The University of Sydney, Charles Perkins Centre, NSW, Australia; The University of Sydney, Physical Activity, Lifestyle, Ageing and Wellbeing Group, Faculty of Health Sciences, NSW, Australia
| | - Ollie Jay
- The University of Sydney, Thermal Ergonomics Laboratory, Faculty of Health Sciences, NSW, Australia; The University of Sydney, Charles Perkins Centre, NSW, Australia.
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de Rome L. Could wearing motorcycle protective clothing compromise rider safety in hot weather? Accid Anal Prev 2019; 128:240-247. [PMID: 31071655 DOI: 10.1016/j.aap.2019.04.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 03/09/2019] [Accepted: 04/16/2019] [Indexed: 06/09/2023]
Abstract
UNLABELLED Motorcycle protective clothing (PPE) effectively reduces the risk of injury in crashes, however in hot conditions many motorcyclists ride unprotected. Recent work found available motorcycle PPE to be thermally inefficient in hot weather with potential to cause significant thermal strain under average Australian summer conditions. The current study investigated the potential for the cognitive and psychophysical concomitants of thermal strain to compromise reaction times, mood and fatigue with potential consequences for motorcyclists' safety. METHOD Volunteers wearing motorcycle PPE participated in a 90 min trial (cycling 30 W) in 35 °C, 40%RH with overhead radiant heaters and a fan to simulate wind speed. Heart rate, core and skin temperature were recorded continuously. Reaction time and subjective ratings of thermal sensation and comfort, workload and mood were recorded at baseline, during rest breaks at 25 min intervals and on completion of the trail. Repeated measures analysis assessed each participant's performance against their own baseline. RESULTS Core temperatures increased by 2 °C (p < .0001), skin temperatures (3 °C, (p < .0001) and heart rates (66bpm, p < .0001). Reaction times fluctuated 36 ms 8% (p < .0001) over the trial. Subjective workload increased 68% (p = 0.001) and mood deteriorated 33 points (p < .0001) including feeling less alert (p = <.0001), contented (p = 0.001) and calm (p = 0.0004). Multivariate repeated measures analysis found significant associations between core temperature and workload (p = 0.01), mood (p = 0.001) and reaction time (<.0001). Skin temperature and workload (p = 0.02), mood (p = 0.01) and reaction time (<.0001). Subjective ratings of temperature sensation and wetness discomfort were associated respectively with increased workload (p = 0.0001, p = 0.004), mood change (p < .0001, p = 0.04) and reaction time (p < .0001, p < .0001). CONCLUSIONS The physiological impact of wearing thermally inefficient motorcycle PPE in hot conditions could impair motorcyclists cognitive and psychophysical functioning and, potentially, their riding performance and safety. These outcomes indicate an urgent need for manufacturers to develop motorcycle PPE that is effective and suitable for use, in hot conditions.
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Affiliation(s)
- Liz de Rome
- Deakin University, Locked Bag 20000, 3220 Geelong, Victoria, Australia.
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Abstract
Finite-element (FE) analysis was used to compare the high-temperature responses of steel columns with two different stress-strain models: the Eurocode 3 model and the model proposed by National Institute of Standards and Technology (NIST). The comparisons were made in three different phases. The first phase compared the critical buckling temperatures predicted using forty seven column data from five different laboratories. The slenderness ratios varied from 34 to 137, and the applied axial load was 20-60 % of the room-temperature capacity. The results showed that the NIST model predicted the buckling temperature as or more accurately than the Eurocode 3 model for four of the five data sets. In the second phase, thirty unique FE models were developed to analyze the W8×35 and W14×53 column specimens with the slenderness ratio about 70. The column specimens were tested under steady-heating conditions with a target temperature in the range of 300-600 °C. The models were developed by combining the material model, temperature distributions in the specimens, and numerical scheme for non-linear analyses. Overall, the models with the NIST material properties and the measured temperature variations showed the results comparable to the test data. The deviations in the results from two different numerical approaches (modified Newton Raphson vs. arc-length) were negligible. The Eurocode 3 model made conservative predictions on the behavior of the column specimens since its retained elastic moduli are smaller than those of the NIST model at elevated temperatures. In the third phase, the column curves calibrated using the NIST model was compared with those prescribed in the ANSI/AISC-360 Appendix 4. The calibrated curve significantly deviated from the current design equation with increasing temperature, especially for the slenderness ratio from 50 to 100.
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Affiliation(s)
- Lisa Choe
- Research Structural Engineer, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA, Tel: +1-301-975-5644
| | - Chao Zhang
- Guest Researcher, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - William E Luecke
- Materials Research Engineer, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - John L Gross
- Research Structural Engineer, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Amit H Varma
- Professor, Purdue University, School of Civil Engineering, West Lafayette, IN 47907, USA
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