Diurnal change in psychological and physiological responses to consistent relative humidity

Diurnal changes in physiological and psychological responses to consistent relative humidity (RH) conditions were investigated in the present study. Lightly clothed six male and six female subjects participated in the first experiment at 40% and 50% RH, and seven male and seven female subjects participated in the second experiment at 60%, 70%, and 80% RH. Both experiments were conducted at 28 °C air temperature (T_a) from 9:00–18:30. Skin temperatures, local heat flux rates and tympanic temperature (T_ty) were monitored at 2-min intervals throughout the experimental period. Body weight loss and oxygen consumption rate were measured during the 9:30–10:30, 13:30–14:30, and 17:30–18:30 periods. Thermal sensation and thermal comfort responses were recorded at the same periods. The amount of heat loss was greater than metabolic heat production (M) in the male subjects but was well balanced with M in the female subjects. A morning increase in T_ty at 50%–80% RH was observed, and mean skin temperature (${\bar{\text{T}}}_{\text{sk}}$) at 70% and 80% RH was significantly higher (p < 0.05) than T_sk at 40% and 50% RH in both subject groups. Although difference in the relationship between thermal sensation and ${\bar{\text{T}}}_{\text{sk}}$ based on sex was confirmed, diurnal changes in thermal sensation were observed in both subject groups based on the responses of “warm” in the morning but “neutral” or “slightly warm” in the evening at 70% and 80% RH. This result demonstrates that high RH may be acceptable in the late afternoon and evening at 28 °C and indicates that dynamic control of RH during the daytime (e.g., low RH in the morning and high RH in late afternoon) may be beneficial to save energy when using air-conditioning.     

Interindividual differences in thermal comfort and the responses to skin cooling in young women

The present study aims to understand the effects of interindividual differences in thermal comfort on the relationship between the preferred temperature and the thermoregulatory responses to ambient cooling. Thirteen young women subjects chose the preferred ambient temperature (preferred T_a) in a climate chamber and were categorized into the H group (preferring ≥29 °C; n=6) and the M group (preferring <29 °C; n=7). The H group preferred warmer sensations than the M group (P<0.05) and the average of preferred T_a was 27.6 °C and 30.2 °C in the M group and H group, respectively. Then all subjects were exposed to temperature variations in the climate chamber. During T_a variations from 33 °C to 25 °C, the H group felt colder than the M group, although no difference was noted in the T_sk (mean skin temperature) and T_s-hand between the 2 groups. From the view of the relationship between the T_sk and thermal sensation, although the thermal sensitivity to the T_sk was almost similar in the H and M groups, the H group might have lower threshold to decreasing T_a than the M group.     

Exploring the effects of warming seas by using the optimal and pejus temperatures of the embryo of three Octopoda species in the Gulf of Mexico

Using data related to thermal optimal and pejus of the embryos of Octopus americanus from Brazil and O. insularis and O. maya from Mexico, this study aimed to project the potential distribution areas in the Gulf of Mexico and predict distribution shifts under different Representative Concentration Pathway scenarios (RCP 6 and 8.5) for the years 2050 and 2100. The different thermal tolerances elicited different responses to current and future scenarios. In this sense, O. insularis and O. maya thermal niches stretch from the Caribbean to Florida. Nevertheless, O. insularis may inhabit warmer areas than O. maya. Surprisingly, no area was considered thermally habitable for O. americanus, which could have been associated with the use of data of populations thermally adapted to temperate conditions south of Brazil. According to models, a warming scenario would cause a restriction of the available thermal niche of O. maya, while O. insularis could expand under RCP 6 scenarios. This restriction was more substantial in the RCP 8.5 scenario. Nevertheless, under the RCP 8.5 scenario, the temperature in 2100 may negatively affect even O. insularis, the species most thermal tolerant. If our results are accurate, the fishing yield of O. insularis will increase in the future, replacing the heavily exploited O. maya in the coasts of the southern Gulf of Mexico. Regarding O. americanus, no inference might be made until thermal tolerances of locally adapted populations can be studied.     

A study of human skin and surface temperatures in stable and unstable thermal environments

Skin temperature is a common physiological parameter that reflects human thermal responses. The purpose of this research was to investigate the effects of radiant temperature on human skin temperature and surface temperature in stable and unstable thermal environments. For a clothed human body, the skin temperature is the surface temperature of the skin, while the surface temperature is the outer surface temperature of the clothes. For this aim, the radiant temperature from 26 to 38 °C and then from 38 to 26 °C was controlled in three different ways; in stable condition keeping stable above 40 min, in unstable condition at a rate of 2 °C/5 min, and in another unstable condition at a rate of 2 °C/10 min. Experimental data showed that at the same radiant temperature, the local skin/surface temperatures during the radiant temperature decrease were higher compared to those during the radiant temperature increase. During the radiant temperature increase/decrease, the increments/decrements of the mean skin temperature and the mean surface temperature decreased gradually from the stable condition, 2 °C/10 min to 2 °C/5 min. Compared to surface temperature, the faster the radiant temperature changed, the more obviously the change in skin temperature was delayed. These data demonstrated that the human body has physiological adaptability to unstable thermal environments.     

Domesticated and wild fathead minnows differ in growth and thermal tolerance

Many populations have evolved in response to laboratory environments (lack of predators, continual food availability, etc.). Another potential agent of selection in the lab is exposure to constant thermal environments. Here, we examined changes in growth, critical thermal maximum (CT_max), and food consumption under constant (25 °C) and fluctuating (22–28 °C and 19–31 °C) conditions in two populations of fathead minnows, Pimephales promelas: one that has been kept in a laboratory setting for over 120 generations (~40 years) and a corresponding wild one. We found that under thermal fluctuations, domesticated fathead minnows grew faster than their wild counterparts, but also exhibited lower thermal tolerance. Food consumption was significantly higher in the lab population under the constant and large fluctuation thermal treatments. Our results suggest that the lab population has adjusted to the stable conditions in the laboratory and that we should carefully apply lessons learned in the lab to wild populations.     

在生物大分子中温度对所激发的孤立子的影响

研究了生物蛋白质分子的温度Ｔ≠ＯＫ和分子链作非线性振动情况下所产生的相干性集体激发和激发的孤立子的特点,此时这类孤立子以超声速运动,其振幅和传递速度都随温度和非线性振动作用改变,但这种热涨落的存在并未多大影响这类孤立子的稳定性,因而在生物学过程中是很有用的。     

在生物大分子中温度对所激发的孤立子的影响

研究了生物蛋白质分子的温度T≠OK和分子链作非线性振动情况下所产生的相干性集体激发和激发的孤立子的特点,此时这类孤立子以超声速运动、其振幅和传递速度都随温度和非线性振动作用改变,但这种热涨落的存在并未多大影响这类孤立子的稳定性.因而在生物学过程中是很有用的.     

Temperature acclimation affects thermal preference and tolerance in three Eremias lizards

We acclimated adult males of three Eremias lizards from different latitudes to 28℃,33℃ or 38℃ to examine whether temperature acclimation affects their thermal preference and tolerance and whether thermal preference and tolerance of these lizards correspond with their latitudinal distributions.Overall,selected body temperature（Tsel）and viable temperature range（VTR）were both highest in E.brenchleyi and lowest in E.multiocellata,with E.argus in between;critical thermal minimum（CTMin）was highest in E.multiocellata and lowest in E.brenchleyi,with E.argus in between;critical thermal maximum（CTMax）was lower in E.multiocellata than in other two species.Lizards acclimated to 28℃ and 38℃ overall selected lower body temperatures than those acclimated to 33℃;lizards acclimated to high temperatures were less tolerant of low temperatures,and vice versa;lizards acclimated to 28℃ were less tolerant of high temperatures but had a wider VTR range than those acclimated to 33℃ and 38℃.Lizards of three species acclimated to the three temperatures always differed from each other in CTMin,but not in Tsel,CTMax and VTR.Our results show that：temperature acclimation plays an important role in influencing thermal preference and tolerance in the three Eremias lizards,although the degrees to which acclimation temperature affects thermal preference and tolerance differ among species;thermal preference rather than tolerance of the three Eremias lizards corresponds with their latitudinal distributions.     

The effects of clothing thermal resistance and operative temperature on human skin temperature

Skin temperature is an essential physiological parameter of thermal comfort. The purpose of this research was to reveal the effects of clothing thermal resistance and operative temperature on local skin temperature (LST) and mean skin temperature (MST). The LSTs (at 32 sites) in stable condition were measured for different clothing thermal resistances 1.39, 0.5 and 0.1 clo. To study the effect of environmental temperature on LST and MST, the LSTs were also measured for operative temperatures 23, 26 and 33 °C. The experimental data showed that the effect of clothing thermal resistance on the foot was greater compared to the other human parts, and the effect of operative temperature on many parts of the human body was great, such as foot, hand, trunk, and arm. The MSTs measured on the conditions that air speed was under 0.1 m/s, RH was about 30–70%, and metabolic rate was about 1 met, were collected from previous studies. On the basis of these experimental data, a MST prediction equation with the operative temperature and clothing thermal resistance as independent variables, was obtained by multiple linear regression. This equation was a good alternative and provided convenience to predict the MST in different operative temperatures and clothing thermal resistances.     

Seasonal adaptation of thermal and metabolic responses in men wearing different clothing at 10° C

Thermoregulatory responses at ambient temperatures of 20 and 10° C in six male subjects wearing two different kinds of clothing were compared between summer and winter. The two different kinds of clothing were one insulating the upper half of the body lightly and the lower half of the body heavily (clothing A, the weight in the upper and lower halves of the body being, respectively, 489 g and 1278 g) and the other insulating the upper half of the body heavily and the lower half of the body lightly (clothing B: 1212 g and 559 g). The major findings are summarized as follow. (i) Rectal temperature was kept significantly higher in clothing B than in clothing A both in summer and winter. (ii) The fall of rectal temperature was significantly greater in summer than in winter in both types of clothing. (iii) Mean skin temperatures and skin temperatures in the face, chest, thigh and leg were significantly lower atT _a of 10° C in summer than in winter in clothing A, while skin temperatures in the face and thigh were also significantly lower atT _a of 10° C in summer than in winter in clothing B. (iv) Metabolic heat production was higher in summer than in winter at 20 and 10° C in both types of clothing. (v) The subjects felt cooler and colder toT _a of 10° C in summer than in winter in both types of clothing. These different responses occurring between summer and winter are discussed mainly in terms of total conductance and dry heat loss.     

The effect of body fat percentage and body fat distribution on skin surface temperature with infrared thermography

This study aimed to search for relations between body fat percentage and skin temperature and to describe possible effects on skin temperature as a result of fat percentage in each anatomical site. Women (26.11±4.41 years old) (n =123) were tested for: body circumferences; skin temperatures (thermal camera); fat percentage and lean mass from trunk, upper and lower limbs; and body fat percentage (Dual-Energy X-Ray Absorptiometry). Values of minimum (T_Mi), maximum (T_Ma), and mean temperatures (T_Me) were acquired in 30 regions of interest. Pearson's correlation was estimated for body circumferences and skin temperature variables with body fat percentage. Participants were divided into groups of high and low fat percentage of each body segment, of which T_Me values were compared with Student's t-test. Linear regression models for predicting body fat percentage were tested. Body fat percentage was positively correlated with body circumferences and palm temperatures, while it was negatively correlated with most temperatures, such as T_Ma and T_Me of posterior thighs (r =−0.495 and −0.432), T_Me of posterior lower limbs (r =−0.488), T_Ma of anterior thighs (r =−0.406) and T_Mi and T_Me of posterior arms (r =−0.447 and −0.430). Higher fat percentages in the specific anatomical sites tended to decrease T_Me, especially in posterior thighs, shanks and arms. Skin temperatures and body circumferences predicted body fat percentage with 58.3% accuracy (R =0.764 and R² =0.583). This study clarifies that skin temperature distribution is influenced by the fat percentage of each body segment.     

Rectal,telemetry pill and tympanic membrane thermometry during exercise heat stress

We compared the accuracy of an ingestible telemetry pill method of core temperature (T_c) measurement and an infrared tympanic membrane thermometer to values from a rectal thermistor during exercise-induced heat stress. Ten well-trained subjects completed four exercise trials consisting of 40 min constant-load exercise at 63% of maximum work rate followed by a 16.1 km time trial at 30 °C and 70% relative humidity. Temperature at rest was not different between the three methods of T_c measurement (T_re: 37.2±0.3 °C; T_p: 37.2±0.2 °C; T_ty: 37.1±0.3 °C; P=0.40$P=0.40$). Temperature rose continuously during the exercise period (ΔT_re: 2.2±0.5 °C; ΔT_p: 2.2±0.5 °C; ΔT_ty: 1.9±0.5 ±°C and there were no differences between T_re and T_p measurements at any time throughout exercise (P=0.32$P=0.32$). While there were no differences between T_re and T_ty after 10 min (P=0.11$P=0.11$) and 20 min (P=0.06$P=0.06$) of exercise, T_ty was lower than T_re after 30 min of exercise (P<0.01$P<0.01$) and remained significantly lower throughout the remainder of the exercise period. These results demonstrate that the telemetry pill system provides a valid measurement of trunk temperature during rest and exercise-induced thermal strain. T_ty was significantly lower than T_re when temperature exceeded 37.5 °C. However, whether these differences are due to selective brain cooling or imperfections in the tympanic membrane thermometer methodology remains to be determined.     

Clothing microclimate temperatures during thermal comfort in boys,young and older men

To examine the effects of age-related differences in thermoregulatory function on the clothing microclimate temperature (T _m) andT _m fluctuations while maintaining thermal comfort in daily life, 5 boys (group B, 10–11 years), 5 young men (group Y, 20–21 years) and 5 older men (group O, 60–65 years) volunteered to take part in this study. The subjects were asked to maintain thermal comfort as closely as possible in their daily lives.T _m (temperatures between the skin surface and the innermost garment) at four sites (chest, back, upper arm, and thigh), skin temperature on the chest (T _chest) and ambient temperature (T _a) were measured over a period of 8–12 h from morning to evening on one day in each of the seasons, spring, summer, autumn, and winter. Records of ability to maintain thermal comfort and of adjustment of their clothes were kept by each subject.T _a during periods of thermal comfort did not differ among the groups in any of the seasons. In group Y,T _m was significantly lower at the thigh than at the other sites in spring, autumn, and winter (P<0.05) and fluctuations (CV) ofT _m were significantly larger at the thigh than at other sites in autumn and winter (P<0.05). Similar tendencies were observed forT _m and CV ofT _m in group B. However,T _m and CV ofT _m in group O did not differ by site except for the autumnT _m. Group O had a smaller CV at the thigh in winter (P<0.05), compared to groups B and Y, suggesting a smaller regional difference inT _m fluctuation in group O. Group O adjusted their clothes even on the lower limbs (together with upper body) in order to maintain thermal comfort in accordance with changes inT _a, while groups B and Y did so only on their upper bodies. These results sugest that compared to boys and young men, lower thermoregulatory function in older men may affectT _m and CV ofT _m as a result of clothing on lower limbs being adjusted differently in order to maintain thermal comfort.     

温州地区小杓鹬的代谢产热特征

动物能量代谢相关的生理生态特征与其地理分布密切相关。为探讨温州地区迁徙鸟类小杓鹬(Numenius minutus)的代谢产热特征及体温调节,本文在环境温度(T_a)5.0～42.5℃范围内,测定了小杓鹬的代谢率(R_m,以单位时间耗氧量表示,ml/h)和体温,并计算不同环境温度的热传导。结果显示：在环境温度为5～35℃的范围内,小杓鹬的体温维持相对恒定,平均体温为(42.8±0.10)℃;热中性区为27.5～40.0℃;在热中性区温度范围内,代谢率即基础代谢率为(221.31±6.01)ml/h,是体重预期值的141%;环境温度在5.0～27.5℃范围内,代谢率与环境温度(T_a,℃)呈负相关,回归方程为R_m=587.10﹣11.78 T_a;在5.0～27.5℃的环境温度范围内,小杓鹬的热传导最低,平均为(0.11±0.00)ml/(g·h·℃),是体重预期值的212%;代谢预期比和热传导预期比的比值(F值)为1.21,表明该物种有较好的体温调节能力。小杓鹬具有较高的体温和基础代谢...     

Validation of a new whole-body cryotherapy chamber based on forced convection

Whole-body cryotherapy (WBC) and partial-body cryotherapy (PBC) are two methods of cold exposure (from −110 to −195 °C according to the manufacturers). However, temperature measurement in the cold chamber during a PBC exposure revealed temperatures ranging from −25 to −50 °C next to the skin of the subjects (using isolating layer placed between the sensor and the skin). This discrepancy is due to the human body heat transfer. Moreover, on the surface of the body, an air layer called the boundary layer is created during the exposure and limits heat transfer from the body to the cabin air. Incorporating forced convection in a chamber with a participant inside could reduce this boundary layer. The aim of this study was to explore the use of a new WBC technology based on forced convection (frontal unilateral wind) through the measurement of skin temperature. Fifteen individuals performed a 3-min WBC exposure at −40 °C with an average wind speed of 2.3 m s⁻¹. The subjects wore a headband, a surgical mask, underwear, gloves and slippers. The skin temperature of the participants was measured with a thermal camera just before exposure, just after exposure and at 1, 3, 5, 10, 15 and 20 min after exposure. Mean skin temperature significantly dropped by 11 °C just after exposure (p<0.001) and then significantly increased during the 20-min post exposure period (p<0.001). No critically low skin temperature was observed at the end of the cold exposure. This decrease was greater than the mean decreases in all the cryosauna devices with reported exposures between −140 °C and −160 °C and those in two other WBC devices with reported exposures between −60 °C and −110 °C. The use of this new technology provides the ability to reach decreases in skin temperature similar to other technologies. The new chamber is suitable and relevant for use as a WBC device.     

中国热带静风区林缘水平热力特征的初步分析

利用我国热静风区－西双版纳橡胶林西南向边缘１月的温度观测资料,探讨了昼间林缘区域热力特征及时空变化规律,结果表明,在林缘存在着明显的热力效应;对地面温度的影响深度可至林内约１３ｍ处,地面温度在林处４．５ｍ处达最高,气温则在林缘（０ｍ）出现最大;林缘附近热量的输送在数值和方向上存在较大差异,即林外热量从地面向空中输送;林内在午后与林外相反,热量由上（林冠）向下（地面）输送;林缘附近则在不同地点、不同     

Does the thermal environment influence vigilance behavior in dark-eyed juncos (Junco hyemalis)? An approach using standard operative temperature

One might expect that increased thermal stress would cause wintering birds to forage faster in order to meet the increased metabolic demand. Faster foraging should, in turn, lead to a reduction in vigilance, since feeding and vigilance are mutually antagonistic activities. We examined these intuitive behavioral expectations using newly developed standard operative temperature sensors designed specifically to characterize the thermal effect of the microclimate environment (rain excluded) on wintering dark-eyed juncos (Junco hyemalis). These sensors allowed us to distinguish the behavioral effects of thermal stress from non-thermal effects associated with micrometeorological conditions (e.g. wind noise). Our analysis indicated that neither thermal nor non-thermal aspects of the physical environment influenced the proportion of time spent vigilant by juncos. However, the rate of food ingestion (measured as pecking rate) exhibited a negative correlation with thermal stress per se. This unexpected result may reflect the effect of thermal stress on feeding posture, peripheral muscle cooling, or both. The effect of thermal stress on pecking rate was nevertheless minor in comparison to the effect of flock size, which exerted by far the largest effect on both vigilance and pecking rate. Our overall results suggest that birds experiencing thermal stress will not necessarily lower their vigilance, but rather increase feeding bout length to compensate for the greater metabolic demand. This interpretation is consistent with theoretical models of vigilance in a non-time-limited environment, and may help explain the contradictory results to date on the effect of thermal stress on vigilance.     

Influence of temperature on female,embryonic and hatchling traits in syntopic newts,Ichthyosaura alpestris and Lissotriton vulgaris

Amphibian populations have been declining globally for the last several decades, and climate change is often regarded as one of the most important factors driving these declines. Amphibians are particularly sensitive to climatic changes due to their physiological, ecological and behavioral characteristics. Here we performed a laboratory experiment to investigate how temperature affects ovipositing females, eggs and hatchlings in two syntopic populations of alpine newts, Ichthyosaura alpestris, and smooth newts, Lissotriton vulgaris. Female newts were assigned to two different oviposition temperatures (11 °C and 14 °C) for the duration of their oviposition period. Deposited eggs were equally divided and assigned to three different incubation temperatures (11 °C, 14 °C and 17 °C). We hypothesized that oviposition will be affected by temperature, that the combination of different oviposition and incubation temperatures may have an effect on embryonic and hatchling traits (embryonic mortality, days to hatch and hatchling length), and that these effects might differ between the two newt species. Temperature affected the number of deposited eggs in smooth newts, but not in alpine newts. Larval hatching success was not affected by oviposition or incubation temperature. Temperature effects on hatching time and hatchling length differed between the two species. These results suggest that temperature changes may have disparate effects on amphibian reproduction, even in syntopic taxa.     

Apparatus for exposing cell membranes to rapid temperature transients

We seek to determine whether cell membranes contain sensors that trigger a downstream response to temperature excursions. To do this, we have developed a novel apparatus for exposing a cell membrane to an extremely rapid temperature excursion in the nanosecond range. Cells are plated on a gold surface that is back-heated by a pulsed laser and cooled by conduction of heat into the glass substrate and the liquid medium. Analysis using the heat diffusion equation shows that the greatest temperature rise is localized within a region tens of nanometres thick, suitable for specifically heating a cell membrane without heating the remainder of a cell. We refer to this device as a nanosecond hotplate.This paper was submitted as a record of the 2002 Australian Biophysical Society     

Preferred ambient temperature for old and young men in summer and winter

To investigate the effects of age on thermal sensitivity, preferred ambient temperature (T _pref) was compared between old (71–76 years) and young (21–30 years) groups, each consisting of six male subjects in summer and winter. The air temperature (T _a) was set at either 20° C or 40° C at commencement. The subject was directed to adjust theT _a for 45 min by manipulating a remote control switch to the level at which he felt most comfortable. In the older group, theT _pref was significantly lower in trials starting at 20° C than that starting at 40° C in summer. The fluctuation ofT _pref (temperature difference between maximum and minimumT _a during the last 10 min) was significantly wider in the older group in both summer and winter. Repetition of the same experiment on each subject showed a poorer reproducibility ofT _pref in the older group than in the younger group in summer. Tympanic and esophageal temperatures of the older group kept falling throughout the trial starting at 20° C in summer. These results suggest that thermal sensitivity is decreased with advancing age and that thermal perception in the elderly, especially to cold, is less sensitive in summer.