Author Keywords: Skin temperature; thermal sensation; comfort; climate heterogeneity 相似文献
1. 1. Seven thermal conditions were imposed on male sitting subjects (slightly clothed: 0.6 clo).
2. 2. A thermal mannikin was also used to determine the exact operative temperature, T0.
3. 3. Conditions were: uniform (UN: all parameters at 24.5°C, air velocity at 0.15 ms−1), heated ceiling (HC at 45°C), heated floor (HF at 34°C), cold floor (CF at 14°C), two conditions of one cold wall at 6°C (CW1 and CW2 respectively with and without air temperature compensation) and increased air velocity (AV at 0.4 ms−1).
4. 4. Local skin temperatures and answers to questionnaires were obtained.
5. 5. Skin temperature variations were affected by conditions and slight T0 changes.
6. 6. Comfort judgments were fairly well related to T0, especially when expressed as differences between actual non-uniform environment and the uniform one.
7. 7. It is concluded that, in case of non-uniform environments close to thermoneutral zone, thermal comfort or discomfort reflects the climate alterations better than the thermal sensation does.
1. 1. The purpose of this paper is to clarify the non-linearity of the human physiological and psychological responses to step change of air temperature by impulse response analysis using Discrete Fourier Transformation.
2. 2. Experiments were conducted to investigate the effect of thermal transients on human responses.
3. 3. Experimental conditions were as follows: lowering air temperature from 30 to 20°C and raising air temperature from 20 to 30°C.
4. 4. The responses of local skin temperature on lowering air temperature from 30 to 20°C are not necessarily opposite to the responses found on raising air temperature from 20 to 30°C.
5. 5. From impulse response analysis using Discrete Fourier Transformation, skin temperature responses to the opposite air temperature change do not necessarily coincide with each other whenever the same temperature stimulus is occurred.
Author Keywords: Air temperature; step change; impulse response; skin temperature; thermal sensation 相似文献
1. 1.The forearm of 5 female subjects ws thermally stimulated by 2 sets of interposed servo-thermodes that respectively drove skin temperature at ±0.1°C.s−1 for 25 s and then held it constant. Mean skin temperature remained constant. The sequence was repeated at adapting temperatures between 22.5 and 37.5°C.
2. 2.Thermal sensations, continuously reported by the position of a dial, were warmer for heterogeneous thermal stimuli than for homogeneous stimuli when mean skin temperature was greater than 30°C and cooler when less than 27.5°C.
3. 3.This phenomenon is inconsistent with a single additive contribution of “warm” and “cold” information to thermal sensations.
Author Keywords: Man; thermal sensation; skin temperature 相似文献
1. 1. The purpose of this study was to investigate the effects of thermal radiation and wind on thermal responses at rest and during exercise in a cold environment.
2. 2. The experimental conditions were radiation and wind (R + W), no radiation and wind (W), radiation and no wind (R), no radiation and no wind (C).
3. 3. The air temperature was −5°C. Thermal radiation was 360 W/m2. Air velocities were 0.76, 1.73 and 2.8 m/s. Rectal and skin temperatures, heart rate and oxygen consumption were recorded. Thermal and comfort sensations were questioned.
4. 4. There are no significant effects of thermal radiation and wind on the physiological responses except the mean skin temperature. There are significant effects on the mean skin temperature (P < 0.01) and thermal sensation (P < 0.05).
Author Keywords: Thermal responses; wind; thermal radiation; exercise; cold environment 相似文献
1. 1. Ten male students remained in a severely cold room (-25°C) for 20 min. thereafter, they transferred in a warm room (25°C) for 20 min.
2. 2. This pattern was repeated three times, total cold exposure time amounting to 60 min.
3. 3. In the warm room, the subjects removed their cold-protective jackets, or wore them continously.
4. 4. Rectal temperature, skin temperatures, manual performance and thermal comfort were measured during the experiment.
5. 5. Removing cold-protective jackets after severe cold exposure increased peripheral skin temperatures and reduced the discomfort in the warm room.
6. 6. However, these results were accompanied by a greater decrease in rectal temperature and manual performance.
7. 7. It is recommended that workers continue to wear cold-protective clothing in the warm areas outside of the cold storage to prevent decreases in deep body temperature and work efficiency caused by repated cold exposures.
Author Keywords: Cold environment; body temperature; manual performance; protective clothing 相似文献
1. 1.|Fourteen male volunteers were examined under passive heating.
2. 2.|Electrical skin resistance (ESR) and rectal temperature (Tre) were measured during the whole period of exposure.
3. 3.|It was found that:
• —|ESR decreases rapidly with increasing air temperature. Assuming an exponential curve yields a mean time constant of 14 min.
• —|There is a correlation between the individual ESR time constants and Tre increases (r = 0.695, P < 0.005).
• —|Additional changes of ESR were noted in 8 subjects at a constant air temperature of 42°C.
4. 4.|It is concluded that ESR may be a useful indicator of the sweating response of the human thermoregulatory system during exogenous heat load.
Author Keywords: Electrical skin resistance; rectal temperature; sweating; heating, man 相似文献
1. 1.Nasal exhalant air temperature in the adult Virginia opossum averages 20.9°C at ambient temperatures near 20.8°C (relative humidity: 47%) and 15.1°C at ambient temperatures near 9.2°C (RH: 78%). Exhalant air temperature is well below deep body temperature (34.5–35.6°C), indicating counterecurrent cooling of the exhalant air in the nasal passages.
2. 2.The extent of cooling of exhalant air is similar in juvenile (15-week-old) and adult opossums.
3. 3.As judged from exhalant air temperature, the effectiveness of countercurrent cooling is similar in the opossum to that seen in small and medium-sized placental mammals. The question is discussed of whether cooling of the exhalant air in these animals represents an adaptation or a physically inevitable, fortuitous effect.
Author Keywords: Didelphis marsupialis; opossum; adaptation; countercurrent cooling; respiration; exhalant air temperature; thermal balance; water balance; marsupial 相似文献
- 1. Heat production (HP) and body core temperature (CT) where measured in 1- to 10-day old Muscovy ducklings and turkey chick, incubated during the last week before hatching at a lower (34.5 °C, LT-group) or at higher (38.5 °C, HT-group), than the normal temperature of 37.5 °C (control C-group).
2. In Muscovy ducklings, on the 1st day post-hatching HP was affected by exposure to low Ta of 10 °C Ta 28.2±3.9 W kg−1 in the LT-group vs. 18.1±2.4 W kg−1 in normal controls. On the same day, CT was higher (39.5±1.1 °C) in the HT- than in the CT-group (37.5±2.9 °C).
3. In turkeys, the relationships between Ta and HP could be described by parabola-like functions. Apart from the first day of life, the HP of the LT-group and the HT-group was higher than of the CT-group.
4. The low prenatal temperature of incubation resulted in a decrease of the preferred temperature in the LH-group and in an increase in the HT-group.
5. It is concluded that changes in incubation temperature at the end of embryonic development may induce an epigenetic temperature adaptation, which results in a long-lasting cold- and warm-adaptation in ducks but not in turkeys.
Keywords: Muscovy duck; Turkey; Epigenetic temperature adaptation; Imprinting; Determination; Heat production 相似文献
1. 1. The purpose of the study was to investigate the preferred temperature of the elderly after cold and heat exposures.
2. 2. Eight elderly and 9 young females wearing the same type of clothing were exposed to cold (10°C), moderate (25°C) or hot (35°C) environments for 30 min in the exposure room.
3. 3. Then they moved to the self-control room in which the temperature was set at 25°C, and the room temperature increased or decreased continuously by 0.4°C every minute.
4. 4. The subjects were instructed to operate the switch when they felt uncomfortably warm or cool during a 90-min period.
5. 5. In operating the switch, the changing in room temperature shifted to the opposite direction.
6. 6. The ambient temperature was recorded continuously and analyzed as the preferred temperature, which was defined as the midpoint temperature of the crest and trough of temperature records.
7. 7. The preferred temperatures after the cold exposure were significantly higher than those of other exposure conditions in the elderly.
8. 8. On the other hand, in the young, there was no significant difference in the preferred temperature among the exposure conditions.
9. 9. Although the effect of exposure to cold or hot environments decreased in the latter parts of self-control, the elderly still preferred the higher temperature after cold exposure.
Author Keywords: Prefered temperature; elderly; selection of air temperature 相似文献
1. 1. The naked mole-rat (Heterocephalus glaber) is a poikilothermic mammal. During gestation metabolic shifts that differ from both mammalian and reptilian thermoregulatory patterns occurred.
2. 2. Body temperature was directly dependent on ambient temperature. At low ambient temperatures the temperature differential (Tb − Ta) was approximately 3°C, whereas at higher ambient temperatures the temperature differential diminished.
3. 3. In early pregnancy (prior to week 3) oxygen consumption at low ambient temperatures was greater than that of non-reproductive animals. A maximal metabolic rate (3.2 ± 1.0 ml O2 . g−1 . h−1) occurred at an ambient temperature of 27°C. Thereafter the endothermic pattern of metabolism with increasing ambient temperatures was evident. Oxygen consumption decreased with increasing ambient temperature to minimal rates of 1.2 ± 0.1 ml O2 . g−1 . h−1 over the ambient temperature range of 31–34°C.
4. 4. Oxygen consumption in late pregnancy (1.8 ± 0.1 ml O2 . g−1 . h−1) was not correlated with ambient temperature over the entire ambient temperature range measured (24–36°C).
5. 5. Differences in thermoregulation in early and late pregnancy may be attributed to different rates of heat loss as a consequence of (a) changes in surface area and body mass or (b) vascular changes. Furthermore the thermoregulatory changes in late pregnancy may indicate that maximal overall metabolic capacity had been reached, for peak resting metabolism (expressed per animal rather than per gram body mass) in early pregnancy was similar to observed metabolism in late pregnancy.
6. 6. The dissociation of metabolism from both ambient temperature and body temperature in late pregnancy could confer an energetic advantage to this arid dwelling underground inhabitant; for it may enable the breeding female to partition a greater portion of available energy into reproduction.
Author Keywords: Body temperature; endothermy; eusocial; gestation; Heterocephalus glaber; metabolic changes; naked mole-rat; oxygen consumption; poikilothermy; pregnancy; rectal temperature; thermoregulation 相似文献
1. 1.|Gemmules of Ephydatia mülleri can withstand exposure to temperatures down to −80°C for 63 days without loss of hatchability.
2. 2.|Hatching is slowed following exposure to temperatures below −27°C.
3. 3.|There is a slight but significant relationship between gemmule size and the time to hatch.
4. 4.|This species can withstand long-term exposure to winter air temperatures occurring within its known geographic range.
Author Keywords: Porifera; Spongillidae; sponge; freshwater sponge; Ephydatia mülleri; gemmule; hatching; low temperature; cold exposure 相似文献
- 1. Each half rete from five Boer goats was perfused with water at 38 °C and flow rate of 2 ml min−1 while simultaneously perfusing the cavernous sinus with water at different temperatures and flow combinations and recording temperatures across the rete.
2. The minimum temperature difference across the rete was recorded at a cavernous sinus perfusion temperature of 37.8 °C and flow rate of 2 ml min−1.
3. Slopes of heat exchange increased threefold when the flow was increased four times.
4. These results support the idea that the rete is an obligate heat exchanger.
Keywords: Carotid rete; Selective brain cooling; Thermoregulation; Artiodactyls; Cavernous sinus 相似文献
1. 1.|Body temperatures (Tb) and contaneous evaporative water loss rates (CWL) were measured in tree frogs (Hyla cinerea) and toads (Bufo valliceps) exposed to cyclical ramp changes in water vapor density (WVD) between 7.5 and 9.8 gm−3 (1 cycle h−1 at an air temperature of 27.0°C.
2. 2.|CWL was 3.3 times greater in toads than in tree frogs.
3. 3.|Tb in toads cycled directly with WVd; WVD accounted for 98% of the variation in toad Tb.
4. 4.|Tb in tree frogs was independent of WVD, probably due to changes in skin resistance to water loss.
Author Keywords: Body temperature; evaporative water loss; skin resistance; water vapor density; relative humidity; Anura; Hyla cinerea; Bufo valliceps 相似文献
1. Entomopathogenic nematodes penetrate and kill Galleria mellonella within 48 h at optimal temperatures.
2. Low temperature induces infection latency, preventing host death until optimal conditions resume.
3. Infected Galleria survived 25 days at 5°C. On transfer to 25°C, 100% and 12.5% of Steinernema carpocapsae and Steinernema riobravis infected larvae died within 72 h.
4. Infective juvenile penetration decreased with decreasing temperature; declining from 49.7 and 49.3 nematodes/host at 25°C to 6.3 and 0.25 nematodes/host at 5°C for S. carpocapsae and S. riobravis, respectively.
5. Latent infection occurs, albeit infrequently, due to low host penetration at low temperature.
Author Keywords: Nematode; Steinernema carpocapsae; Steinernema riobravis; Low temperature 相似文献
1. 1. 10 elderly and 10 college-aged females served as subjects in cold and heat environments. The subjects changed into the standard clothing (0.63 clo), and stayed in the neutral environment (25°C) for 23 min, thereafter they were exposed to the cold (10°C) or hot (35°C) environment for 49 min.
2. 2. Then they returned to the neutral environment, and stayed there for 47 min. Oral temperature, skin temperatures at 10 sites, blood pressure and thermal sensation were measured during the experiments.
3. 3. In the cold environment, the elderly could not reduce heat loss by vasoconstriction as did young people, and their blood pressures increased more rapidly than in young people. In the hot environment, the elderly could not promote heat loss by vasodilation as did young people. Moreover, there is a delayed sensitivity to cold for the elderly. Therefore, in the houses of the elderly, it is important to have heating and cooling systems which also includes the areas where the people do not stay for a long period of time (e.g. toilet, passageways).
Author Keywords: Cold; heat; body temperature; thermal sensation; elderly 相似文献
1. 1. In order to investigate the thermoregulatory responses to the non-uniform thermal environment of the human body, the effects of cooling 10 different body regions were compared by circulating cool water to the neck, breast, back, loin, upper-arms, lower-arms, hands, thighs, legs and feet, respectively. Tympanic temperature, regional (11 sites) and mean skin temperature, and the thermal sensations were measured during experiment in which 30 min local coolings were applied on 5 female students in a climatic chamber controlled at 30°C and 50% r.h.
2. 2. The skin temperature beneath the cooling pad decreased in the order of arms, legs, hands and feet, and trunk.
3. 3. The temperature drop was significantly correlated with the thermal sensation of the region itself.
4. 4. On the other hand, the tympanic temperature increased once by any local cooling. The increase of it was correlated with the change of the general thermal sensation.
5. 5. Results of principal component analysis of skin temperature showed that the peripheral cooling affected the skin temperature in the limited peripheral regions, while the effects of cooling of the breast and the back extended to both the central and peripheral.
Author Keywords: Local cooling; skin temperature; tympanic temperature; thermal sensation; principal component analysis 相似文献
- 1 Metabolic rates (Vo2), body temperature (Tb), and thermal conductance (C) were first determined in newly captured Maximowiczi's voles (Microtus maximowiczii) and Djungarian hamsters (Phodopus campbelli) from the Inner Mongolian grasslands at a temperature range from 5 to 35 °C.
2 The thermal neutral zone (TNZ) was between 25 and 32.5 °C for Maximowiczi's voles and between 25 and 30 °C for Djungarian hamsters. Mean Tb was 37.0±0.1 °C for voles and 36.2±0.1 °C for hamsters. Minimum thermal conductance was 0.172±0.004 ml O2/g h °C for voles and 0.148±0.003 ml O2/g h °C for hamsters.
3 The mean resting metabolic rate within TNZ was 2.21±0.05 ml O2/g h in voles and 2.01±0.07 ml O2/g h in hamsters. Nonshivering thermogenesis was 5.36±0.30 ml O2/g h for voles and 6.30±0.18 ml O2/g h for hamsters.
4 All these thermal physiological properties are adaptive for each species and are shaped by both macroenvironmental and microenvironmental conditions, food habits, phylogeny and other factors.
Keywords: Basal metabolic rate; Body temperature; Djungarian hamster (Phodopus campbelli); Maximowiczi's vole (Microtus maximowiczii); Nonshivering thermogenesis; Minimum thermal conductance 相似文献
1. 1. Our previous experimental results showed the thermal sensation vote was much less than the values of PMV and SET* at air velocities above 0.5 m/s.
2. 2. The method to modify SET* is presented from the results of subjective experiments taking account of decrease in clo value of summer clothing and decrease in skin wettedness due to increased air velocity.
3. 3. Thermal resistance under increased air movement on a standard summer clothing ensemble was measured. Basic thermal insulation of the summer ensemble was reduced by 25% at air velocity of 1.0 m/s.
4. 4. Thirty-two subjects were exposed at operative temperatures of 27 and 30°C under 1 m/s air movement in order to determine the amount of skin diffusion. Measured evaporation heat loss from skin surface was much smaller at air velocity of 1 m/s than that predicted by SET*.
5. 5. Estimated thermal sensation vote using modified SET* agreed well with our previous experimental results under different air velocities for the same clothing.
Author Keywords: Thermal comfort; air movement; SET*; hot and humid condition 相似文献
1. 1.|Dinitrophenol (DNP) was administered to rats in two equal dosages (20 mg/kg, 30 min interval); the second injection was followed immediately by exercise (9.14 m/min) in the heat (30°C) or at room temperature (21°C).
2. 2.|At 21°C control (saline-treated) rats manifested a mean endurance of 94 min which was reduced to 32 min among DNP-treated animals.
3. 3.|At 30°C, control rats ran for 65 min (δTre/min = 0.05°C) while DNP-treated animals had a mean endurance of only 12 min (δTre/min = 0.22°C).
4. 4.|DNP-treated rats (30°C) manifested no decrements in tail-skin heat loss (δTsk/min = 0.17°C vs 0.10°C) or saliva secretion (0.78 g/min, DNP vs. 0.19 g/min, control) for their brief treadmill duration.
5. 5.|The increased metabolic heat production of DNP severely reduced performance.
Author Keywords: Dinitrophenol; exercise; heat stress; endurnace; temperature regulation 相似文献
1. The aim of this study was to investigate if finger temperature or finger blood flow is the critical factor for maintenance of finger dexterity during cold exposure.
2. Subjects were exposed twice to −25°C air for 3 h by using a Torso Heating Test (THT) where the torso was maintained to 42°C with a heating vest while the hands were bare, and a Hand Heating Test (HHT) where the hands were heated with heated gloves.
3. Despite similar finger temperatures, finger blood flow was eight times lower and finger dexterity was decreased in HHT as compared to THT.
4. It is concluded that finger blood flow is the critical factor to maintain finger dexterity in the cold.
Author Keywords: Finger dexterity; Finger temperature; Auxiliary heating; Cold exposure; Heating gloves; Torso heating; Comfort of extremities 相似文献