Modelling hand skin temperature in relation to body composition

Skin temperature is a challenging parameter to predict due to the complex interaction of physical and physiological variations. Previous studies concerning the correlation of regional physiological characteristics and body composition showed that obese people have higher hand skin temperature compared to the normal weight people. To predict hand skin temperature in a different environment, a two-node hand thermophysiological model was developed and validated with published experimental data. In addition, a sensitivity analysis was performed which showed that the variations in skin blood flow and blood temperature are most influential on hand skin temperature. The hand model was applied to simulate the hand skin temperature of the obese and normal weight subgroup in different ambient conditions. Higher skin blood flow and blood temperature were used in the simulation of obese people. The results showed a good agreement with experimental data from the literature, with the maximum difference of 0.31 °C. If the difference between blood flow and blood temperature of obese and normal weight people was not taken into account, the hand skin temperature of obese people was predicted with an average deviation of 1.42 °C. In conclusion, when modelling hand skin temperatures, it should be considered that regional skin temperature distribution differs in obese and normal weight people.     

Physiological responses of growing Large White boars in three management environments

Growth and physiological responses in Large White boars were studied under three different management environments at the Teaching and Research Farm of the Federal University of Technology, Akure. The management environments were shed with concrete floor (SCF), open space with concrete floor (OSCF) and open space with earth floor (OSEF). Two studies were carried out, one between December 1990 and March 1991 and the other from December 1991 to April 1992. Meteorological parameters in all management environments were monitored simultaneously with physiological variables. Growth of the animals was assessed by monitoring body weights of the animals. Data analysis showed that mean ambient temperatures, mean relative humidity and net radiation differed significantly (P<0.05) among the management environments. Ambient temperature and net radiation of the pigs were highest (P<0.05) in the OSEF environment, which also had the lowest (P<0.05) relative humidity. Although growth rates did not differ significantly among environments, body weight was lowest (P<0.05) in the OSEF environment. Mean respiratory rates and rectal temperatures were lowest (P<0.05) in the SCF environment. The study shows correlations between some meteorological parameters and body weights. Pigs under shade and in concrete-floored pens were more comfortable and had higher body weight and lower respiratory rates and rectal temperatures.     

Experimental and numerical study of physiological responses in hot environments

This paper proposed a multi-node human thermal model to predict human thermal responses in hot environments. The model was extended based on the Tanabe's work by considering the effects of high temperature on heat production, blood flow rate, and heat exchange coefficients. Five healthy men dressed in shorts were exposed in thermal neutral (29 °C) and high temperature (45 °C) environments. The rectal temperatures and skin temperatures of seven human body segments were continuously measured during the experiment. Validation of this model was conducted with experimental data. The results showed that the current model could accurately predict the skin and core temperatures in terms of the tendency and absolute values. In the human body segments expect calf and trunk, the temperature differences between the experimental data and the predicted results in high temperature environment were smaller than those in the thermally neutral environment conditions. The extended model was proved to be capable of predicting accurately human physiological responses in hot environments.     

Effects of color temperature of fluorescent lamps on body temperature regulation in a moderately cold environment

A study on the effects of different color temperatures of fluorescent lamps on skin and rectal temperatures in a moderately cold environment involving (i) changes in skin temperature of 7 male subjects exposed to an ambient temperature ranging from 28 degrees C to 18 degrees C (experiment I) and (ii) changes in skin and rectal temperatures and metabolic heat production of 11 male subjects exposed to ambient temperature of 15 degrees C for 90 min (Experiment II) was conducted. In Experiment I, the reduction of mean skin temperature from the control value was significantly greater under 3000 K than under 5000 K or 7500 K lighting. In Experiment II, the reductions in mean skin temperature and rectal temperature were respectively greater and smaller under 3000 K than those under 5000 K or 7500 K lighting. However, metabolic heat production was not affected by color temperature conditions. The relationships between morphological and physiological parameters revealed that no significant relation of rectal temperature to body surface area per unit body weight was found only under 3000 K. Furthermore, while the mean skin temperature was independent on the mean skinfold thickness under 3000 K, a significant negative correlation between the rectal and mean skin temperatures was observed. Therefore, body heat loss might be suppressed effectively by increasing the vasoconstrictor tone under a color temperature of 3000 K, and the body shell was dependent only on morphological factors under 5000 K and 7500 K lighting.     

Use of physiological parameters to predict milk yield and feed intake in heat-stressed dairy cows

Holstein cows were tested to determine which measures of thermal strain are the better predictors of production over 24–96 h at constant air temperatures of 19 and 29 °C. Both rectal temperature and respiration rate increased within 24 h, followed by milk yield and feed intake reductions after 48 h of heat stress. There were significant correlations between milk yield, feed intake, and rectal temperature. Several physiological strain indices were created to determine if combinations of measures are better than single measures in predicting production under these acute conditions. Mean daily rectal temperature was superior to maximum and minimum daily values of rectal temperature, as well as other indicators of thermal status in predicting dairy cow production. Likewise, mean daily rectal temperature was equal if not better than the physiological strain indices used in this study in predicting production. These data suggest that rectal temperature is superior to both single and combined indicators of thermal status in predicting dairy cow production, and should be considered for future development of physiological strain indices over a longer time period in both laboratory and field environments.     

Are development and growth of pea aphids,Acyrthosiphon pisum,in North America adapted to local temperatures?

Summary Developmental rate and adult weight were studied at constant temperatures from 9.8 to 27.9°C for 18 clones from each of five populations of the pea aphid, Acyrthosiphon pisum (Harris), from locations between 39 and 53°N latitude in central North America. The response of developmental rate to temperature for each clone was accurately described by a three parameter non-linear equation. Adult weight usually decreased with increasing rearing temperature, but the shape of the response to temperature varied among clones. Variation in the developmental parameters was greater among clones within populations than among populations. No consistent trends were observed in the developmental parameters or adult weights either with latitude or the long term average temperatures at the locations. We conclude that previously reported geographic variation in the developmental threshold of this species, which was attributed to local adaptation, occurred either because the clones tested were not representative of the populations or because rearing methods differed among studies. The results are discussed in relation to the hypothesis that life history traits which are temperature sensitive are adapted to local thermal environments.Contribution No. 1257, Agriculture Canada, Research Station, Winnipeg, Manitoba, Canada     

Circadian rhythms in bed rest: Monitoring core body temperature via heat-flux approach is superior to skin surface temperature

Continuous recordings of core body temperature (CBT) are a well-established approach in describing circadian rhythms. Given the discomfort of invasive CBT measurement techniques, the use of skin temperature recordings has been proposed as a surrogate. More recently, we proposed a heat-flux approach (the so-called Double Sensor) for monitoring CBT. Studies investigating the reliability of the heat-flux approach over a 24-hour period, as well as comparisons with skin temperature recordings, are however lacking. The first aim of the study was therefore to compare rectal, skin, and heat-flux temperature recordings for monitoring circadian rhythm. In addition, to assess the optimal placement of sensor probes, we also investigated the effect of different anatomical measurement sites, i.e. sensor probes positioned at the forehead vs. the sternum. Data were collected as part of the Berlin BedRest study (BBR2-2) under controlled, standardized, and thermoneutral conditions. 24-hours temperature data of seven healthy males were collected after 50 days of -6° head-down tilt bed-rest. Mean Pearson correlation coefficients indicated a high association between rectal and forehead temperature recordings (r > 0.80 for skin and Double Sensor). In contrast, only a poor to moderate relationship was observed for sensors positioned at the sternum (r = -0.02 and r = 0.52 for skin and Double Sensor, respectively). Cross-correlation analyses further confirmed the feasibility of the forehead as a preferred monitoring site. The phase difference between forehead Double Sensor and rectal recordings was not statistically different from zero (p = 0.313), and was significantly smaller than the phase difference between forehead skin and rectal temperatures (p = 0.016). These findings were substantiated by cosinor analyses, revealing significant differences for mesor, amplitude, and acrophase between rectal and forehead skin temperature recordings, but not between forehead Double Sensor and rectal temperature measurements. Finally, Bland-Altman analysis indicated narrower limits of agreement for rhythm parameters between rectal and Double Sensor measurements compared to between rectal and skin recordings, irrespective of the measurement site (i.e. forehead, sternum). Based on these data we conclude that (1) Double Sensor recordings are significantly superior to skin temperature measurements for non-invasively assessing the circadian rhythm of rectal temperature, and (2) temperature rhythms from the sternum are less reliable than from the forehead. We suggest that forehead Double Sensor recordings may provide a surrogate for rectal temperature in circadian rhythm research, where constant routine protocols are applied. Future studies will be needed to assess the sensor’s ecological validity outside the laboratory under changing environmental and physiological conditions.     

A study on body temperature regulation and residential thermal environments of the elderly—I. whole country survey of residential thermal environment and evaluation methods: RTE-index

1. 1. As part of “research on environmental comfort,” that is, research which aims to make people's living environment more comfortable, we attempted to clarify the relation between the living environment of elderly people and physiological and psychological factors. We carried out a comprehensive study with a view to establishing comfort standards for the residential thermal environment, and for creating evaluation and control systems.

2. 2. The comfort of the living environment is closely related to the thermal environment and the temperature-regulation ability of the human body. This ability of the body to regulate temperature develops during childhood and recedes as the adult ages.

3. 3. We therefore carried out: (a) experiments on body-temperature regulation and on special characteristics of the body-temperature regulation of elderly people, (b) a nationwide survey of the actual residential thermal environments of elderly people and (c) a survey of the daily activities of elderly people, and how elderly people's physiological and psychological conditions change when they are engaged in these activities.

4. 4. As a result of these experiments and surveys, we were able to: (d) formulate standards for evaluation of the residential thermal environment and (e) numerically express the results of systematic evaluation of residential thermal environments of elderly people, by means of a RTE-index.

A physio-anthropological approach in evaluation of human adaptability to living environment: in the case of artificial light environment

Attention has been focused on human adaptability to human-adopted artificially modern and comfortable environments which may not always match the adaptability by the physiological state of humans. This discrepancy was found to induce a slight tension in the human body on evaluation with a physio-anthropological approach. Although a standard methodological approach has yet to be established, the present study attempted to evaluate human adaptability to artificial light environment, based on evaluations from three major possible perspectives: a) central nervous system, b) autonomic nervous system and c) biological rhythm. In order to detect the slight tension, human volunteers were exposed to an artificial light environment, and the appropriate physiological parameters were then examined from photic signal pathways in a brain. The findings revealed that a higher color temperature of fluorescent lamps induced a slight tension, although many other factors remained to be elucidated.     

The influence of the thermal environment and other early life events on growth rate of piglets during lactation

The effects of early life events on average daily weight gain from birth to day 21 (ADG) of suckling pigs kept at different room temperatures (15°C, 20°C and 25°C) from birth to weaning were investigated. Data were collected from litters born by 61 sows in a loose housing system. The ADG for piglets with low birth weight (estimated for birth weights below the 10% percentile) was estimated to be 20 to 30 g higher per day at room temperature 20°C to 25°C compared with 15°C. In contrast, the ADG during the lactation period decreased for larger piglets (estimated for birth weights above the 10% percentile) by 28 g/day at room temperature 25°C compared with 15°C. Thus, high ambient temperatures (20°C to 25°C) are favourable for the growth in smaller piglets during lactation. Neither latency to first suckle nor birth-induced hypoxia, measured as concentration of umbilical cord lactate, affected the growth rate of the piglets. Lowest rectal temperature during the first 24 h after birth had a long-term negative effect on ADG (P<0.05), so that piglets with a lowest rectal temperature of 32.8°C (10% percentile) had an ADG which was on average 19 g lower per day than piglets with a rectal temperature of 37.3°C (90% percentile). Our results showed that hypothermia at birth, low birth weight and high number of suckling piglets lead to reduced ADG during the suckling period. The results suggest that keeping the room temperature at 20°C during lactation to some extent could compensate for the otherwise negative effects of low birth weight on ADG in piglets without decreasing the ADG of high birth weight piglets. However, to avoid hypothermia in the smallest piglets it may be beneficial to increase the room temperature above 20°C during the farrowing period of loose housed sows.     

Prediction of human core body temperature using non-invasive measurement methods

The measurement of core body temperature is an efficient method for monitoring heat stress amongst workers in hot conditions. However, invasive measurement of core body temperature (e.g. rectal, intestinal, oesophageal temperature) is impractical for such applications. Therefore, the aim of this study was to define relevant non-invasive measures to predict core body temperature under various conditions. We conducted two human subject studies with different experimental protocols, different environmental temperatures (10 °C, 30 °C) and different subjects. In both studies the same non-invasive measurement methods (skin temperature, skin heat flux, heart rate) were applied. A principle component analysis was conducted to extract independent factors, which were then used in a linear regression model. We identified six parameters (three skin temperatures, two skin heat fluxes and heart rate), which were included for the calculation of two factors. The predictive value of these factors for core body temperature was evaluated by a multiple regression analysis. The calculated root mean square deviation (rmsd) was in the range from 0.28 °C to 0.34 °C for all environmental conditions. These errors are similar to previous models using non-invasive measures to predict core body temperature. The results from this study illustrate that multiple physiological parameters (e.g. skin temperature and skin heat fluxes) are needed to predict core body temperature. In addition, the physiological measurements chosen in this study and the algorithm defined in this work are potentially applicable as real-time core body temperature monitoring to assess health risk in broad range of working conditions.     

Bed climate of Korean using ondol heating system

1. 1. To examine the influence of different bed conditions (ondol sleep, bed sleep on ondol with same bedding) of the Korean ondol traditional heating system on human response during sleep, bed climates and physiological responses such as skin and rectal temperatures, weight loss, body movement and subjective sensation were measured with 4 grown-up females as subjects while they were sleeping for 7 h.

2. 2. Bed climate: Temperatures under the mattress and inside the quilt were higher on ondol while temperatures on the mattress and humidity inside the quilt were higher on the bed.

3. 3. Rectal temperature was significantly higher on ondol; skin temperature showed no major differences in relation to bed conditions. The frequency of body movements had the highest correlation with bed climate of the parameters measured.

4. 4. Mattress weight decreased on ondol and increased on the bed.

5. 5. The frequency of body movements was significantly higher in ondol sleep.

6. 6. The subjects sensation showed difference on cushion sensation between the two types of bed condition.

7. 7. To obtain the same level of comfort on both ondol and bed sleeping conditions less thermal insulating value is needed for ondol sleep.

Comparison between sex and age class on some physiological, thermal, and hematological indices of the cerrado's marmoset (Callithrix penicillata)

There are few papers about physiological indices in Callithrix penicillata, an increasing primate model in biomedicine. We investigated levels of plasmatic cortisol, plasmatic glucose, free fatty acids, blood cells, tympanic temperature, rectal temperature in C. penicllata, under a fast restraint. Measures of body and weight were accomplished. Males and females were not different regarding any measurements. Body measurements indicated differences between adults and juveniles. Adults showed higher hematocrit and a tendency for higher free fatty acids than juveniles. Right tympanic temperature was higher in adults than juveniles. This result suggests a higher reaction metabolism in adults than juveniles under a restraint stress. Due to the short-time of collecting the data, plasmatic cortisol did not influence physiological parameters. Therefore, we suggest that present results could be considered referential values of C. penicillata physiology.     

The influence of animals from embryo transfer on the genetic evaluation of growth in Simmental beef cattle by using multi-trait models

The weight records from Simmental beef cattle were used in a genetic evaluation of growth with or without the inclusion of animals obtained by embryo transfer. A multi-trait model in which embryo transfer individuals were excluded (MTM1) contained 29,510 records from 10,659 animals, while another model without exclusion of these animals (MTM2) contained 62,895 weight records from 23,160 animals. The weight records were adjusted for ages of 100, 205, 365, 450, 550 and 730 days. The (co)variance components and genetic parameters were estimated by the restricted maximum likelihood method. The (co)variance components were similar in both models, except for maternal permanent environment variance. Direct heritabilities (h²_d) in MTM1 were 0.04, 0.11, 0.20, 0.27, 0.31 and 0.42, while in MTM2 they were 0.11, 0.11, 0.17, 0.21, 0.22 and 0.26 for 100, 205, 365, 450, 550 and 730 days of age, respectively. Estimates of h²_d in MTM1 were higher than in MTM2 for the weight at 365 days of age. Genetic correlations between weights in both models ranged from moderate to high, suggesting that these traits may be determined mainly by the same genes. Animals from embryo transfer may be included in the genetic evaluation of Simmental beef cattle in Brazil; this inclusion may provide potential gains in accuracy and genetic gains by reducing the interval between generations.     

In vivo thermal conductivity of the human forearm tissues

The effective thermal conductivities of the skin + subcutaneous (keff skin + fat) and muscle (keff muscle) tissues of the human forearm at thermal steady state during immersion in water at temperatures (Tw) ranging from 15 to 36 degrees C were determined. Tissue temperature (Tt) was continuously monitored by a calibrated multicouple probe during a 3-h immersion of the resting forearm. Tt was measured every 5 mm from the longitudinal axis of the forearm (determined from computed-tomography scanning) to the skin surface. Skin temperature (Tsk), heat loss (Hsk), and blood flow (Q) of the forearm, as well as rectal temperature (Tre) and arterial blood temperature at the brachial artery (Tbla), were measured during the experiments. When the keff values were calculated from the finite-element (FE) solution of the bioheat equation, keff skin + fat ranged from 0.28 +/- 0.03 to 0.73 +/- 0.14 W.degrees C-1.m-1 and keff muscle varied between 0.56 +/- 0.05 and 1.91 +/- 0.19 W.degrees C-1.m-1 from 15 to 36 degrees C. The values of keff skin + fat and keff muscle, calculated from the FE solution for Tw less than or equal to 30 degrees C, were not different from the average in vitro values obtained from the literature. The keff values of the forearm tissues were linearly related (r = 0.80, P less than 0.001) to Q for Tw greater than or equal to 30 degrees C. It was found that the muscle tissue could account for 92 +/- 1% of the total forearm insulation during immersion in water between 15 and 36 degrees C.     

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.     

Thermoregulatory model for immersion of humans in cold water

The mathematical models of thermoregulation of Stolwijk and Hardy, and Montgomery were used to develop a model suitable for the simulation of human physiological responses to cold-water immersion. Data were obtained from experiments where 13 healthy male volunteers were totally immersed under resting and nude conditions for 1 h in water temperatures of 20 and 28 degrees C. At these temperatures, the mean measured rectal temperature (Tre) fell by approximately 0.9 and 0.5 degrees C, respectively, yet mean measured metabolic rate (M) rose by approximately 275 and 90 W for the low body fat group (n = 7) and 195 and 45 W for the moderate body fat group (n = 6). To predict the observed Tre and M values, the present model 1) included thermal inputs for shivering from the skin independent of their inclusion with the central temperature to account for the observed initial rapid rise in M, 2) determined a thermally neutral body temperature profile such that the measured and predicted initial values of Tre and M were matched, 3) confined the initial shivering to the trunk region to avoid an overly large predicted initial rate of rectal cooling, and 4) calculated the steady-state convective heat loss by assuming a zero heat storage in the skin compartment to circumvent the acute sensitivity to the small skin-water temperature difference when using conventional methods. The last three modifications are unique to thermoregulatory modeling.     

Infrared methodologies for the assessment of skin temperature daily rhythm in two domestic mammalian species

To assess the accuracy of infrared methodologies for daily rhythm monitoring of skin temperature, five clinically healthy Italian Saddle gelding horses, and five not pregnant and not lactating Camosciata goats, were monitored every 4 h over a 48 h period. The horses were housed in individual boxes, while the goats in two indoor pens, under natural photoperiod and natural environmental temperature. In each animal, skin temperature was recorded with the use of a digital infrared camera and a non-contact infrared thermometer, in five regions: neck, shoulder, ribs, flank and croup. Recorded values were compared with the well-established daily rhythm of rectal temperature. Rectal temperature was recorded at the same time by means of a digital thermometer. In horses, a lower value of skin temperature was recorded using the infrared thermometer for the croup region compared to shoulder and flank; a lower value of skin temperature was recorded using thermography for the croup region compared to the shoulder. In goats, a lower value of skin temperature was recorded using the infrared thermometer for the croup region compared to the flank. In both species, higher values of rectal temperature were observed, compared to the temperature recorded at the skin regions using the other two methodologies. Cosinor rhythmometry showed a daily rhythm of rectal and skin temperature recorded using both methodologies in all the examined regions. General linear model (GLM) showed statistically significant effect of breed on all rhythmic parameters; of day of monitoring on amplitude; of site of recording (rectal vs skin regions) on mesor, amplitude and acrophase; and no effect of methodologies used. The results of this study show the differences in rhythmicity of various body regions temperature and their differences in comparison with daily rhythm rectal temperature. The use of infrared methodologies was inaccurate in assessing body core temperature, but its use could be considered for the evaluation of inflammation in the different body sites.     

F1代西藏小型猪早期生长发育特点

目的研究西藏小型猪早期生长发育的规律。方法对本基地F1代西藏小型猪的体重、体长、胸围、体高、体温、呼吸频率、心率及血液生理生化指标进行了测定。结果西藏小型猪体型小,生长性能稳定,生长速度与原产地西藏小型猪基本一致;西藏小型猪的体温、呼吸次数和心率与原产地西藏小型猪相近,且雌雄之间差异不显著(P>0.05);F1代雌雄间除嗜碱性粒细胞、单核细胞数和尿素氮外其他指标也基本一致,大部分指标与人接近。结论由于西藏小型猪体型小、生长性能稳定,血液生理生化值与人类相近,因而是理想的医学研究用实验动物。     

A comparison of the suitabilities of rectal,gut, and insulated axilla temperatures for measurement of the circadian rhythm of core temperature in field studies

Eight healthy males were studied for a total of 13 subject-days to assess if gut (from an ingested pill) and axilla (from a thermally insulated skin probe) temperatures would act as a substitute for rectal temperature in field studies of the circadian rhythm of core temperature. Subjects slept and went about their activities, indoors and outdoors, normally. Regular recordings (at 6min intervals) were made of temperatures from the three sites. In addition, activity was measured (by a sensor on the nondominant wrist) so that the raw temperature data could be “purified,” that is, corrected for the direct effects of sleep and activity. Inspection of the raw data indicated that there was a close parallelism between rectal and gut temperatures, but that the parallelism between rectal and insulated axilla temperatures was less reliable. This parallelism was supported by initial calculations of the correlations between rectal and gut temperatures (high and positive) and between rectal and insulated axilla (lower, though still positive) temperatures. Calculation of the limits of agreement between the parameters of the cosine curves fitted to the raw data confirmed that the rectal and gut temperatures were far closer with regard to acrophase and amplitude than were rectal and insulated axilla temperatures (-0.31±0.89 vs. +0.75±6.03 h and +0.002±0.116 vs. +0.083±0.625°C, respectively). After purification of the temperature data, the limits of agreement for the cosine parameters acrophase and amplitude still indicated that there was a closer agreement between rectal and gut temperatures than between rectal and insulated axilla temperatures (-0.30±1.12 vs. +0.58±6.69 h, and +0.007±0.116 vs. +0.104±0.620°C, respectively). Part of the explanation of this difference was the unreliable relationships between temperature changes in insulated axilla temperature and bursts of activity and going to bed. It is concluded that, whereas gut temperature is a viable alternative to rectal temperature (from the viewpoints of both user acceptability and the reliability of data obtained), insulated axilla temperature, though acceptable to subjects, is unreliable from an experimental viewpoint.