Application of a Predictive Coke Temperature Model to Heat Stress Experimentation

An interactive procedure for evaluating and maintaining an individual's core temperature at a predetermined level was developed and tested. The procedure involved the use of previously developed models for predicting core temperature changes during work and rest. Various levels of metabolic activity were used for rapid core temperature elevation and adjustments in dry-bulb temperature and relative humidity maintained the desired core temperature level. Evaluation of the procedure was made using five female subjects at four different levels of elevation. Results are presented which show the accuracy of the control.

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Core temperature and sweating onset in humans acclimated to heat given at a fixed daily time

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1999.276.4.r1095 ◽

1999 ◽

Vol 276 (4) ◽

pp. R1095-R1101 ◽

Cited By ~ 17

Author(s):

Osamu Shido ◽

Naotoshi Sugimoto ◽

Minoru Tanabe ◽

Sotaro Sakurada

Keyword(s):

Relative Humidity ◽

Core Temperature ◽

Heat Exposure ◽

Heat Acclimation ◽

Fixed Time ◽

Temperature Level ◽

Before And After ◽

Thermoregulatory Function ◽

Daily Time ◽

Made In

The thermoregulatory functions of rats acclimated to heat given daily at a fixed time are altered, especially during the period in which they were previously exposed to heat. In this study, we investigated the existence of similar phenomena in humans. Volunteers were exposed to an ambient temperature (Ta) of 46°C and a relative humidity of 20% for 4 h (1400–1800) for 9–10 consecutive days. In the first experiment, the rectal temperatures (Tre) of six subjects were measured over 24 h at a Ta of 27°C with and without heat acclimation. Heat acclimation significantly lowered Tre only between 1400 and 1800. In the second experiment, six subjects rested in a chair at a Ta of 28°C and a relative humidity of 40% with both legs immersed in warm water (42°C) for 30 min. The Tre and sweating rates at the forearm and chest were measured. Measurements were made in the morning (0900–1100) and afternoon (1500–1700) on the same day before and after heat acclimation. Heat acclimation shortened the sweating latency and decreased the threshold Tre for sweating. However, these changes were significant only in the afternoon. The results suggest that repeated heat exposure in humans, limited to a fixed time daily, alters the core temperature level and thermoregulatory function, especially during the period in which the subjects had previously been exposed to heat.

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Physiological tolerance to uncompensable heat stress: effects of exercise intensity, protective clothing, and climate

Journal of Applied Physiology ◽

10.1152/jappl.1994.77.1.216 ◽

1994 ◽

Vol 77 (1) ◽

pp. 216-222 ◽

Cited By ~ 135

Author(s):

S. J. Montain ◽

M. N. Sawka ◽

B. S. Cadarette ◽

M. D. Quigley ◽

J. M. McKay

Keyword(s):

Heat Stress ◽

Relative Humidity ◽

Core Temperature ◽

Exercise Intensity ◽

Protective Clothing ◽

Heat Exposure ◽

Heat Strain ◽

Published Data ◽

Physiological Tolerance ◽

Uncompensable Heat Stress

This study determined the influence of exercise intensity, protective clothing level, and climate on physiological tolerance to uncompensable heat stress. It also compared the relationship between core temperature and the incidence of exhaustion from heat strain for persons wearing protective clothing to previously published data of unclothed persons during uncompensable heat stress. Seven heat-acclimated men attempted 180-min treadmill walks at metabolic rates of approximately 425 and 600 W while wearing full (clo = 1.5) or partial (clo = 1.3) protective clothing in both a desert (43 degrees C dry bulb, 20% relative humidity, wind 2.2 m/s) and tropical (35 degrees C dry bulb, 50% relative humidity, wind 2.2 m/s) climate. During these trials, the evaporative cooling required to maintain thermal balance exceeded the maximal evaporative capacity of the environment and core temperature continued to rise until exhaustion from heat strain occurred. Our findings concerning exhaustion from heat strain are 1) full encapsulation in protective clothing reduces physiological tolerance as core temperature at exhaustion was lower (P < 0.05) in fully than in partially clothed persons, 2) partial encapsulation results in physiological tolerance similar to that reported for unclothed persons, 3) raising metabolic rate from 400 to 600 W does not alter physiological tolerance when subjects are fully clothed, and 4) physiological tolerance is similar when subjects are wearing protective clothing in desert and tropical climates having the same wet bulb globe thermometer. These findings can improve occupational safety guidelines for human heat exposure, as they provide further evidence that the incidence of exhaustion from heat strain can be predicted from core temperature.

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Heat strain models applicable for protective clothing systems: comparison of core temperature response

Journal of Applied Physiology ◽

10.1152/jappl.1997.83.3.1017 ◽

1997 ◽

Vol 83 (3) ◽

pp. 1017-1032 ◽

Cited By ~ 49

Author(s):

R. R. Gonzalez ◽

T. M. McLellan ◽

W. R. Withey ◽

S. K. Chang ◽

K. B. Pandolf

Keyword(s):

Heat Stress ◽

Wind Speed ◽

Relative Humidity ◽

Ambient Temperature ◽

Core Temperature ◽

Protective Clothing ◽

Temperature Response ◽

The United States ◽

Heat Strain ◽

Intermittent Work

Gonzalez, R. R., T. M. McLellan, W. R. Withey, S. K. Chang, and K. B. Pandolf. Heat strain models applicable for protective clothing systems: comparison of core temperature response. J. Appl. Physiol. 83(3): 1017–1032, 1997.—Core temperature (Tc) output comparisons were analyzed from thermal models applicable to persons wearing protective clothing. The two models evaluated were the United States (US) Army Research Institute of Environmental Medicine (USARIEM) heat strain experimental model and the United Kingdom (UK) Loughborough (LUT25) model. Data were derived from collaborative heat-acclimation studies conducted by three organizations and included an intermittent-work protocol (Canada) and a continuous-exercise/heat stress protocol (UK and US). Volunteers from the US and the UK were exposed to a standard exercise/heat stress protocol (ambient temperature 35°C/50% relative humidity, wind speed 1 m/s, level treadmill speed 1.34 m/s). Canadian Forces volunteers did an intermittent-work protocol (15 min moderate work/15 min rest at ambient temperature of 40°C/30% relative humidity, wind speed ≈0.4 m/s). Each model reliably predicted Tc responses (within the margin of error determined by 1 root mean square deviation) during work in the heat with protective clothing. Models that are analytically similar to the classic Stolwijk-Hardy model serve as robust operational tools for prediction of physiological heat strain when modified to incorporate clothing heat-exchange factors.

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Acute heat stress protects rats against endotoxin shock

Journal of Applied Physiology ◽

10.1152/jappl.1992.73.4.1517 ◽

1992 ◽

Vol 73 (4) ◽

pp. 1517-1522 ◽

Cited By ~ 102

Author(s):

A. J. Ryan ◽

S. W. Flanagan ◽

P. L. Moseley ◽

C. V. Gisolfi

Keyword(s):

Escherichia Coli ◽

Heat Stress ◽

Relative Humidity ◽

Ambient Temperature ◽

Core Temperature ◽

Endotoxin Shock ◽

Time Of Day ◽

Acute Heat Stress ◽

Arterial Plasma ◽

Lps Treatment

The purpose of this study was to determine 1) whether prior (24-h) heat stress could render rats cross-resistant to the lethal activity of bacterial lipopolysaccharide (LPS) and 2) whether this acquired state of resistance is associated with endotoxemia during the heat stress event. Four groups (n = 7/group) of rats were examined: 1) saline treated, 2) LPS treated, 3) heat stressed and saline treated, and 4) heat stressed and LPS treated. Saline or LPS (Escherichia coli, serotype 0111:B4, 20 mg/kg body wt) was given intravenously 24 h after exposure to heat (ambient temperature 47–50 degrees C, relative humidity 30%) for heat-stressed rats and at the same time of day for nonheated rats; survival was monitored for 48 h. Thermal responses were similar (P > 0.05); values for maximum core temperature (Tc) and time above Tc of 40 degrees C were 42.7 +/- 0.1 and 42.6 +/- 0.1 degrees C (SE) and 44.0 +/- 2.1 and 47.9 +/- 3.7 (SE) min for the heat-stressed saline-treated and heat-stressed LPS-treated rats, respectively. Administration of LPS to nonheated rats resulted in 71.4% (5 of 7 rats) lethality. In contrast, all (7 of 7) rats subjected to a single nonlethal heat stress event 24 h before LPS treatment survived (P < 0.05). Endotoxin was not detected in arterial plasma immediately after heat stress in rats (n = 6) exposed to a Tc of 42.9 +/- 0.1 degrees C. These findings demonstrate that acute heat stress can protect rats from the lethal activity of LPS.

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The Relative Contributions of Temperature and Moisture to Heat Stress Changes under Warming

Journal of Climate ◽

10.1175/jcli-d-20-0262.1 ◽

2021 ◽

Vol 34 (3) ◽

pp. 901-917

Author(s):

Nicholas J. Lutsko

Keyword(s):

Heat Stress ◽

Relative Humidity ◽

Climate Model ◽

Potential Temperature ◽

Specific Humidity ◽

Temperature Changes ◽

Equivalent Potential ◽

Stress Changes ◽

Intercomparison Project ◽

Health And Mortality

AbstractIncreases in the severity of heat stress extremes are potentially one of the most impactful consequences of climate change, affecting human comfort, productivity, health, and mortality in many places on Earth. Heat stress results from a combination of elevated temperature and humidity, but the relative contributions of each of these to heat stress changes have yet to be quantified. Here, conditions for the baseline specific humidity are derived for when specific humidity or temperature dominates heat stress changes, as measured using the equivalent potential temperature (θE). Separate conditions are derived over ocean and over land, in addition to a condition for when relative humidity changes make a larger contribution than the Clausius–Clapeyron response at fixed relative humidity. These conditions are used to interpret the θE responses in transient warming simulations with an ensemble of models participating in phase 6 of the Climate Model Intercomparison Project. The regional pattern of θE changes is shown to be largely determined by the pattern of specific humidity changes, with the pattern of temperature changes playing a secondary role. This holds whether considering changes in seasonal-mean θE or in extreme (98th-percentile) θE events, and uncertainty in the response of specific humidity to warming is shown to be the leading source of uncertainty in the θE response at most land locations. Finally, analysis of ERA5 data demonstrates that the pattern of observed θE changes is also well explained by the pattern of specific humidity changes. These results demonstrate that understanding regional changes in specific humidity is largely sufficient for understanding regional changes in heat stress.

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The Effect Of Outside Corridor’s Orientation to Interior Thermal Condition at Lawang Sewu Semarang.

E3S Web of Conferences ◽

10.1051/e3sconf/20187301011 ◽

2018 ◽

Vol 73 ◽

pp. 01011

Author(s):

Benediktus Yosef Arya Wastunimpuna ◽

Wahyu Setia Budi ◽

Erni Setyowati

Keyword(s):

Heat Stress ◽

Relative Humidity ◽

Thermal Condition ◽

Natural Ventilation ◽

Thermal Conditions ◽

Standard Theory ◽

Hot Wire ◽

Air Movement ◽

Dutch Colonial

The outside corridor of Dutch Colonial Building in Indonesia was made to make the temperature of the room more comfortable. Lawang Sewu Building in Semarang is one example of a building that has an outside corridor along the building and until now still use natural ventilation. This study focuses on finding out whether there is a difference on the thermal conditions of each room’s orientation, so after that we know the effect of orientation of the outdoor corridor to the temperature of the interior. In this study the experiment based on measurement using Heat Stress WBGT Meter for Wet Bulb Temperature, Dry Bulb Temperature, Relative Humidity, and KW0600653 Hot Wire Anemometer for the air movement. The data will be analysed using thermal standard theory to find out which point has the most comfortable thermal conditions.. At the end of this study will be found the effect of corridor’s orientation to thermal condition of the interior in Lawang Sewu Semarang.

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The effect of post-harvest storage on the weight of Golden Delicious apples

Science Technology and Innovation ◽

10.5604/01.3001.0015.5265 ◽

2021 ◽

Vol 13 (2) ◽

pp. 7-11

Author(s):

Salma Kassebi ◽

Péter Korzenszky

Keyword(s):

Relative Humidity ◽

Storage Temperature ◽

Extended Period ◽

Food Products ◽

Significant Loss ◽

Loss Of Weight ◽

Ambient Storage ◽

Golden Delicious ◽

Different Levels ◽

Careful Management

Apples, like other fruits, are exposed to stress during their growth and development in the field, also during harvest and the postharvest environment (processing, storage, and transportation). The refrigeration system allows for bulk handling of food products from harvest to market, ensuring that food products are maintained in their freshness and integrity for an extended period through careful management of storage temperature and humidity. This study investigated the effects of storage on the weight loss of apples (Golden Delicious fruits harvested at maturity), under refrigerated conditions at a temperature of 5±0.5°C and relative humidity of 82% and under ambient storage at a temperature of 25 ±0.5 °C and relative humidity of 60 %, over 3 months. The findings revealed that the two groups of apples experienced weight reduction at different levels. Apples placed at cold storage presented a loss of weight between 3.31g and 4.49g; however, apples stored at ambient temperature showed a significant loss of weight between 21.9g and 31.76g.

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