[The physiological indicator value of skin temperature of the arm for estimating changes in temperature of the body surface due to thermal modifications of the environment].
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Adult↗
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Results for “Temperature environment”
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Effect of temperature, elevated carbon dioxide, and drought during seed development on the isoflavone content of dwarf soybean [Glycine max (L.) Merrill] grown in controlled environments.
The effects of elevated temperature, carbon dioxide, and water stress on the isoflavone content of seed from a dwarf soybean line [Glycine max (L.) Merrill] were determined, using controlled environment chambers. Increasing the temperature from 18 degrees C during seed development to 23 degrees C decreased total isoflavone content by about 65%. A further 5 degrees C increase to 28 degrees C decreased the total isoflavone content by about 90%. Combining treatments at elevated temperature with elevated CO(2) (700 ppm) and water stress to determine the possible consequences of global climate change on soybean seed isoflavone content indicated that elevated CO(2) at elevated temperatures could partially reverse the effects of temperature on soybean seed isoflavone content. The addition of drought stress to plants grown at 23 degrees C and elevated CO(2) returned the total isoflavone levels to the control values obtained at 18 degrees C and 400 ppm CO(2). The promotive effects of drought and elevated CO(2) at 23 degrees C on the 6' '-O-malonygenistin and genistin levels were additive. The individual isoflavones often had different responses to the various growth conditions during seed maturation, modifying the proportions of the principal isoflavones. Therefore, subtle changes in certain environmental factors may change the isoflavone content of commercially grown soybean, altering the nutritional values of soy products.
Carbon Dioxide↗
Effect of modafinil on core temperature during sustained wakefulness and exercise in a warm environment.
BACKGROUND: Previous studies have revealed that modafinil elevates resting core temperature during periods of sustained wakefulness. The purpose of this study was to examine the effects of modafinil on core temperature during rest and exercise throughout 40 h of sustained wakefulness in a warm environment. METHODS: Ten males performed a drug session (three 100 mg doses per day) and a placebo session that involved a control day, 40 h of sustained wakefulness, and a recovery sleep. For 38 h of the sustained wakefulness, subjects were exposed to 30 degrees C with 50% relative humidity. During the afternoon of both days of wakefulness and during the early morning of the second day, subjects performed 2 h of exercise at 60% VO2max while exposed to the warm environment. RESULTS: The data revealed that rectal temperature (Tre) was elevated at rest 0.15-0.2 degrees C following modafinil ingestion throughout the period of sustained wakefulness. This increase in body temperature at rest was due to an increase in heat production during the first day of wakefulness followed by a lower evaporative heat loss during the second day. During exercise, an inconsistent effect of the drug on Tre was observed throughout the 38-h period. On the first afternoon, the impact of modafinil on Tre was no longer evident after 20 min of exercise. In contrast, during the early morning and afternoon of the second day, the effects of the drug on Tre at rest remained during exercise. For seven subjects who had Tre data for 80 min during all exercise periods, Tre during the placebo session was 38.9, 38.4, and 38.7 degrees C after 80 min of exercise for periods one, two and three, respectively, whereas the corresponding values during the modafinil session were 38.8, 38.7, and 38.9 degrees C. CONCLUSION: With a greater cumulative dose of the drug, Tre remained elevated throughout the exercise period to an extent similar to the increase observed under resting conditions when compared with the placebo condition.
Adult↗
[Etiology and sequelae of perioperative accidental hypothermia].
Accidental hypothermia is a frequent event during the perioperative period. Recent studies revealed a drop in core temperature of over 2 degrees C in more than 50% of all patients undergoing an operation. This drop in core temperature seems to be primarily due to the following factors. Anaesthesia prevents behavioural adaptations to changes in ambient temperature. Simultaneously, autonomic mechanisms of temperature control are suppressed by general as well as by neuraxial anaesthesia. The interthreshold range between core temperatures that trigger responses to warmth and to cold increases up to 20-fold. This is primarily due to a decrease in the cold response threshold. As a result, body core temperature of anaesthetized patients is primarily determined by the much lower temperature of the environment. On one hand, decreases in body temperatures may exert organ protective effects under certain conditions, e.g., by increasing ischemic tolerance. On the other hand, there is accumulating evidence that accidental perioperative hypothermia may also adversely affect organ function and outcome. For example, unfavourable effects of perioperative hypothermia on the immune defence, on the function of the coagulation system, on cardiovascular performance, as well as on postoperative recovery have been reported. Consequently, measures should be taken to actively control the perioperative heat balance of patients.
Autonomic Nervous System↗
[Influence of the central temperature on the choice of thermal environment in the dog].
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Animals↗
Differences in the physiological responses to temperature among stonechats from three populations reared in a common environment.
The physiological response to variation in air temperature (T(a)) can provide insights into how animals are adapted to different environments. I measured metabolic rate, total evaporative water loss (TEWL) and body temperature (T(b)) as a function of T(a) in stonechats from equatorial Kenya, temperate central Europe and continental Kazakhstan, environments where stonechats have evolved different life histories. All birds were raised and kept under identical captive conditions to highlight genetically based differences and to exclude phenotypic plasticity as explanatory factor. The slope relating metabolic rate to T(a) was steepest in Kazakh stonechats and lowest for birds from Kenya, indicating that, counterintuitively, the tropical stonechats were best insulated. Taking into account variation in T(b) in response to T(a), the lower critical temperature for the three populations fell between 32.0 and 34.9 degrees C, values higher than previously assumed. Whole organism BMR did not differ among populations, but because body mass was significantly higher in the Kenyan stonechats, their mass-specific BMR was lower compared with conspecifics from higher latitude. Whole organism or mass-specific TEWL did not differ among populations. Possibly, Kenyan birds are better insulated to compensate for their limited capacity to elevate metabolic rate.
Adaptation, Physiological↗
The influence of working cast residual moisture and temperature on the fit of vacuum-forming athletic mouth guards.
STATEMENT OF PROBLEM: The comfort and effectiveness of athletic mouth guards are believed to depend on their degree of fit to oral tissues. Vacuum-forming machines are simpler and less expensive than pressure-forming machines. However, it is thought that vacuum-formed mouth guards often do not exhibit adequate adaptation. PURPOSE: The purpose of this study was to evaluate the effects of cast residual moisture and temperature on the fit of athletic mouth guards made with a vacuum-forming machine. MATERIAL AND METHODS: A metal master model simulating the cross section of the maxillary molar region was used to form 20 working plaster casts. The casts represented 4 (5 specimens each) conditions before the forming of the mouth guard specimens: storing in a wet environment at room temperature and storing in a dry environment at room temperature, 5 degrees C, and 40 degrees C. Mouth guard specimens were fabricated with ethylene vinyl acetate sheets (3.8-mm thick) with the use of a vacuum-forming machine. Test casts were created by pouring hand-mixed type III dental stone into each of the mouth guard specimens. The differences in the sagittal cross-sectional heights at the line angle area of the test casts and the working casts were compared. This was achieved by superimposing their 3-dimensional images scanned by a laser scanner. The air permeability was also measured for the hand-mixed stone casts under wet and dry conditions, the vacuum-mixed stone cast, and the high-strength stone specimen. This was achieved by measuring the volume of transmitted air passing through the specimen in the testing tube. One-way analysis of variance with the Scheffé post hoc test (P <.05) was applied to determine the conditions of the working cast required to achieve the best fit. RESULTS: With regard to the fit of the mouth guard specimens to the working cast, those with dry and heated working casts showed a significantly better fit than those with wet working casts (P<.05). A significantly larger volume of transmitted air was found in the dry stone specimen (P<.05) followed by the dry high-strength stone cast and then the wet stone cast. CONCLUSION: Within the limitations of this study, residual moisture in the working cast was the most critical factor in determining the fit of the mouth guard made by vacuum-forming machines. The best fit was achieved when the working cast was thoroughly dried and its surface temperature was elevated.
Air↗
Apparatus for controlling temperature of catheter contents in cold environments.
An apparatus was developed to prevent the freezing of catheter contents during blood sampling or liquid infusion into animals maintained at sub-freezing temperatures. The apparatus consisted of a larger, outer set of plastic and copper tubes and a smaller, inner set of tubes. The catheter was passed inside the inner set. Water circulated through the outer set kept the contents of the catheter inside the inner set from freezing. The apparatus was also useful for the rapid cooling of blood to a predetermined temperature while a sample was being withdrawn from an animal.
Animals↗
Forehead skin temperature and thermal sensation during exercise in cool and thermoneutral environments.
BACKGROUND: The influence of forehead and mean skin temperature on thermal sensation during exercise in hot, cool, and thermoneutral environments is unclear. HYPOTHESIS: We hypothesized that forehead temperature, in contrast to other skin sites, would contribute significantly to thermal sensation during exercise in hot, cool, and thermoneutral environments. METHOD: Volunteer males (N = 14) performed 30 min of constant load exercise on a cycle ergometer during which thermal sensation, skin and rectal temperatures, and heart rate were collected. Each subject participated in a control (24 degrees C), hot (40 degrees C), and cool (8 degrees C) condition. RESULTS: Significantly higher mean skin temperatures occurred during exercise in the hot condition (M = 37.22 +/- 0.20 degrees C) compared to exercise in the neutral (M = 33.34 +/- 0.51 degrees C) and cool conditions (M = 27.92 +/- 0.22 degrees C). Forehead skin temperature in the neutral and cool conditions was significantly greater than forearm, hand, thigh, and calf skin temperatures (p < 0.05). In the hot condition, forehead temperature was significantly greater than back, chest, upper arm, and hand skin temperatures (p < 0.05). In contrast to the neutral and hot conditions, forehead skin temperature was significantly associated with thermal sensation during exercise in the cool condition (r consistently > 0.67). CONCLUSIONS: We conclude that forehead skin temperature, in contrast to other skin sites, contributed significantly to thermal sensation during exercise in the cool.
Adult↗
A comparison of the tympanic and axillary temperatures of the preterm and term infant.
A correlational research design was used to examine the accuracy between the axillary and tympanic temperature measurements of the preterm and term infant. Also examined was the effect of weight and environment on the temperature measurements. A convenience sample of 40 neonates (preterm, n = 20; term, n = 20) was selected. A correlation of 0.815 (p = 0.001) was found between the axillary and tympanic temperatures of all subjects, and correlations of 0.861 (p = 0.001) and 0.582 (p = 0.01) were revealed for the preterm and term infants, respectively. When weight was used as a covariate, there was no significant difference in the two temperature measurements by group (preterm, term), but there was a trend for tympanic temperatures, and the difference between axillary and tympanic temperatures, to differ by environment (radiant warmer, incubator, or open crib).
Axilla↗
[TEMPERATURE OF EXHALED AIR IN COLD ENVIRONMENT].
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Air↗
Expired air temperature during prolonged exercise in cool- and hot-humid environments.
The purpose of this investigation was to measure expired air temperature under cool- and hot-humid environmental conditions at rest and during prolonged exercise to: (1) establish if significant increases in body core temperature affected expired air temperature, and (2) to determine if the temperature setting for heating the pneumotachometer in an open-circuit system requires adjustment during prolonged exercise tests to account for changes in expired air temperature. Six male distance runners completed two tests in cool-humid [dry bulb temperature (Tdb) 15.5 (SD 1.3) degrees C, wet bulb temperature (TWb) 12.1 (SD 1.4) degrees C] and hot-humid [Tdb 31.6 (SD 0.6) degrees C, TWb 24.9 (SD 0.6) degrees C, black globe temperature (Tg) 34.3 (SD 0.3) degrees C] environments, running at a velocity corresponding to 65% [67.1 (SD 2.82)%] of their maximal oxygen uptake. Rectal temperature and expired air temperatures were compared at rest, and after 30 min and 60 min of exercise for each environment. The main finding of this investigation was a significant (P < 0.05) but small increase in expired air temperature between the 30-min and 60-min measures in the hot-humid environment. No significant differences in expired air temperature were found between the 30-min and 60-min measures in the cool-humid environment. These findings suggest that: (1) expired air temperature is influenced by elevations in body core temperature during prolonged exercise in hot-humid conditions, and (2) that the temperature setting for heating the head of the pneumotachometer (after determining the appropriate temperature through measuring expired air temperature for the set environmental condition) may require adjustment during prolonged exercise trials in hot-humid environmental conditions.
Adult↗
A nuclear magnetic resonance study of enzyme-inhibitor association. The use of pH and temperature effects to probe the binding environments.
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Binding Sites↗
Prediction of air temperature for thermal comfort of people in outdoor environments.
Current thermal comfort indices do not take into account the effects of wind and body movement on the thermal resistance and vapor resistance of clothing. This may cause public health problem, e.g. cold-related mortality. Based on the energy balance equation and heat exchanges between a clothed body and the outdoor environment, a mathematical model was developed to determine the air temperature at which an average adult, wearing a specific outdoor clothing and engaging in a given activity, attains thermal comfort under outdoor environment condition. The results indicated low clothing insulation, less physical activity and high wind speed lead to high air temperature prediction for thermal comfort. More accurate air temperature prediction is able to prevent wearers from hypothermia under cold conditions.
Air↗
Blood and brain temperatures of free-ranging black wildebeest in their natural environment.
Using miniature data loggers, we measured the temperatures of carotid blood and brain in four wildebeest (Connochaetes gnou) every 2 min for 3 wk and every 5 min, in two of the animals, for a further 6 wk. The animals ranged freely in their natural habitat, in which there was no shelter. They were subject to intense radiant heat (maximum approximately 1,000 W/m2) during the day. Arterial blood temperature showed a circadian rhythm with low amplitude (< 1 degree C) and peaked in early evening. Brain temperature was usually within 0.2 degrees C of arterial blood temperature. Above a threshold between 38.8 and 39.2 degrees C, brain temperature tended to plateau so that the animals exhibited selective brain cooling. However, selective brain cooling sometimes was absent even when blood temperature was high and present when it was low. During helicopter chases, selective brain cooling was absent, even though brain temperature was near 42 degrees C. We believe that selective brain cooling is controlled by brain temperature but is modulated by sympathetic nervous system status. In particular, selective brain cooling may be abolished by high sympathetic activity even at high brain temperatures.
Animals↗
The relative influence of urban climates on outdoor human energy budgets and skin temperature. II. Man in an urban environment.
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Climate↗
Thermal acclimation and the dynamic response of plant respiration to temperature.
Temperature-mediated changes in plant respiration (R) are now accepted as an important component of the biosphere's response to global climate change. Here we discuss the underlying mechanisms responsible for the dynamic response of plant respiration to short and long-term temperature changes. The Q(10) is often assumed to be 2.0 (i.e. R doubles per 10 degrees C rise in temperature); however, the Q(10) is not constant (e.g. it declines near-linearly with increasing temperature). The temperature dependence of Q(10) is linked to shifts in the control exerted by maximum enzyme activity at low temperature and substrate limitations at high temperature. In the long term, acclimation of R to temperature is common, in effect reducing the temperature sensitivity of R to changes in thermal environment, with the temperature during plant development setting the maximal thermal acclimation of R.
Acclimatization↗
Fluctuation-dissipation relations in driven dissipative systems.
Exact theoretical results for the violation of time-dependent fluctuation-dissipation relations in driven dissipative systems are presented. The ratio of the correlation to delayed response in the stochastic model introduced in [Phys. Rev. Lett. 93, 240601 (2004)] is shown to depend on measurement time. The fluctuation temperature defined by this ratio differs both from the temperature of the environment performing the driving, and from other effective temperatures of the system, such as the average energy (or "granular temperature"). General explanations are given for the time independence of the fluctuation temperature for simple measurements or long measurement times.
Journal Article↗