Heat-transfer relations of avian nestlings

1. 1.|To determine the thermoregulatory prowess of altricial nestlings, we conducted both equilibrium and transient analyses of white-crowned sparrow nestings, a representative fringillid.

2. 2.|For an individual nestling at thermal equilibrium, feather development is the major factor reducing heat loss after 2 days of age; tissue- and boundary-layer resistances are of minor importance.

3. 3.|The nest substantially reduces wind speeds near the nestlings. Heat transfer through the nest material is of only moderate importance. Evaporation also appears to be a small proportion of total heat loss during hypothermia in natural environments.

4. 4.|Net long-wave radiant exchange is also minor, but short-wave radiation is potentially a major component of the nestling's energy budget, approaching the magnitude of maximal metabolic heat production.

5. 5.|When nestlings cool, their body mass and metabolic rate are also major importance in determining the rate of cooling, and (for metabolism) the equilibrium temperature as well.

6. 6.|The huddling together of nestlings is perhaps the single most important factor affecting heat transfer.

7. 7.|An older brood actually has more insulation than does an adult in the same microclimate.

Mismatch between temperature preferences and morphology in F1 hybrid newts (Triturus carnifex×T. dobrogicus)

1. The influence of interspecific hybridization on temperature preferences and morphology was examined in newts, Triturus carnifex and Triturus dobrogicus, before and after metamorphosis.

2. Thermoregulatory behavior was measured in an aquatic thermal gradient (5–32.5 °C) during 24 h.

3. Hybrid temperature preferences were similar to preferences of maternal species in both premetamorphic larvae and recently metamorphosed individuals.

4. Hybrid morphology (i.e., forelimb length and axilla–groin distance) was intermediate relative to parental species.

5. The mismatch between morphology and thermal preference in hybrid phenotypes indicates potential hybrid disadvantage in both intermediate and parental habitats.

Behavioural thermoregulation in two species of robber flies occupying different grassland microhabitats

1. 1.|The robber flies Machimus occidentalis and Machimus formosus are ambush predators that occur sympatrically in grassland habitats of southwestern Montana, U.S.A., although the former occurs earlier in the season.

2. 2.|Early in daily foraging periods, when ambient temperatures are relatively low, the two species exhibited similar behaviours. They perched in a crouched posture on fully insolated bare soil surfaces and oriented their longitudinal and dorsoventral axes to maximize the incident solar radiation intercepted by the broad lateral surface of the thorax. Measurements of operative body temperature of flies in different locations, orientations, and postures indicate that such basking can significantly raise body temperature.

3. 3.|Their thermoregulatory tactics diverged as daily temperatures and solar radiation loads rise.

4. 4.|Like previous grassland species studied, M. occidentalis moved upward onto vegetation, where crouched postures and orientation to the sun disappeared.

5. 5.|Machimus formosus, on the other hand, took refuge in the shaded portions of ground squirrel (Citellus sp.) and badger (Taxidea taxus) burrows.

6. 6.|In both cases, the vertical movements resulted in lower body temperatures than would occur if flies remained on the fully insolated soil surfaces.

7. 7.|We compare the tactics of these two species with those of previous grassland species studied.

Responses of human skin temperature and thermal sensation to step change of air temperature

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.

Comparison of thermal responses with and without cold protective clothing in a warm environment after severe cold exposures

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.

Thermoregulatory effects of central injection of noradrenaline in the new-born columbian ground squirrel (Spermophilus columbianus)

1. 1.Effects of centrally injected noradrenaline (NA) into new-born (12–300 h. post-partum) Columbian ground squirrels (Spermophilus columbianus) were studied to provide comparative data on ontogeny of the thermoregulatory pathways in a hibernating species.

2. 2.At warm ambient temperatures (32–34°C, similar to nest temperature), NA increased heat production (47–92%). rectal temperature (0.27–1.73°C), and axillary temperature (0.59–1.92°C). Peak magnitudes of heat production increased with increasing age on a per unit weight basis.

3. 3.At lower temperatures (28–31°C), NA had no effect on heat production.

4. 4.The data indicate that metabolic and thermal responses to NA in neonates of hibernating species are comparable (e.g. rabbit. guinea pig) or different (e.g. lamb) from those observed in neonates of non-hibernating species.

Sleep and the temperature field of the bed

1. 1. In order to find a correlation between the thermal conditions in bed and the quality of sleep, 5 young, healthy persons were tested in a thermal climate chamber.

2. 2. The sleep of each person was thoroughly monitored during 5 nights (stages I to IV, REM, awake) with continuous registration of 14 temperatures, 12 distributed in the bed, the distal skin temperature and the ambient temperature.

3. 3. Shortly after the test persons went to bed and shortly after they woke up their blood pressure and pulse were taken and they were asked to fill in a questionnaire.

4. 4. The results of this pilot project show a correlation between the quality of sleep and the variations of temperature and that larger fluctuations of temperature in the bed are connected to a shorter deep-sleep time.

5. 5. In order to investigate the thermal comfort it is recommended to undertake detailed analyses of the time and exact interplay between the local thermal conditions during sleep and changes of the sleep-EEG.

Skin temperatures, thermosensory and pleasantness estimates in case of heterogeneity in the thermal environment

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.

Diel thermoregulation of the crawfish Procambarus Clarkii (crustacea, cambaridae)

1. 1. In a diel cycle Procambarus clarkii has two preferred temperatures: 24.0 ± 0.15 SEM °C during the day and 26.7 ± 0.13 SEM °C at night.

2. 2. The preferred temperatures are independent from the weight of the organisms.

3. 3. In the photophase the animals are dispersed, in the scotophase they congregate.

4. 4. The crawfish seem to feed during the thermal interphases.

5. 5. Animals in a constantly dark condition maintain a diel preferendum of temperature.

Tolerances of Nauplii of Balanus balanoides (L.) and Elminius modestus (Darwin) exposed to cyclical temperature fluctuations

1. 1.|Newly-released larvae of both E. modestus and B. balanoides show similar tolerances to steady temperature levels.

2. 2.|Both species show an ability to withstand a wider range of temperatures when subjected to cyclic thermal shocks.

3. 3.|E. modestus shows a greater tolerance to short-term thermal shocks than B. balanoides.

Thermal parameters of four species of Gerbillurus

1. 1.Thermal parameter of the four Gerbillurus species measured in the laboratory were examined in relation to their micro-environments in a xeric habitat.

2. 2.Basal metabolic rates (BMR) were lower than predicted, while thermoneutral zonds (TNZ) were narrow and exceeded burrow temperatures.

3. 3.Body temperatures (T_b) were regulated over a range of ambient temperatures (T_a). Evaporative water loss was used as a short-term cooling mechanism to reduce hyperthermia above the TNZ.

4. 4.Conductance was low below the TNZ to reduce heat loss.

5. 5.Adaptation to low temperatures is important for gerbils when active at night.

6. 6.The adaptive significance of the thermal biology of Gerbillurus is discussed in relation to phylogeny, distribution, food availability and nocturnal activity.

A new device for measurement of the thermal conductivity of fur and blubber

1. 1. A new and simple device for measurements of thermal conductivity of fur and blubber is described.

2. 2. The device measures temperature differences across the sample and across a polyethylene plate with known conductivity which is placed in series with the sample.

3. 3. The conductivity of the polyethylene was determined from the steady state temperature difference and heat flux through the wall of a polyethylene pipe with a central heat source.

4. 4. The accuracy of the device is ±4.0%.

5. 5. The thermal conductivity of harp seal (Phoca groenlandica) and minke whale (Balaenoptera acutorostrata) blubber, as determined by use of this device, is very close to previously reported values.

Relationship between cerebrovascular disease and indoor thermal environment in two selected towns in Miyagi Prefecture, Japan

1. 1. This paper describes the results of an investigation of the relationship between mortality from cerebrovascular disease (hereafter called stroke) and the indoor thermal environment in two selected towns with different socioeconomic compositions: Shiwahime, an agricultura town with relatively high stroke mortality, and Karakuwa, a fishing town with relatively low stroke mortality, using a case-control research design.

2. 2. The measurement of the indoor thermal environments were conducted and the surveyed with a questionnaire during the winter of 1986.

3. 3. The findings are summarized as detailed below.

4. 4. Room temperatures in the control households were generally higher than those in the case households by up to 1.3°C.

5. 5. The thermal conditions of the housing in the case households were a little inferior to those in the control households.

6. 6. Despite much lower room temperatures than the so-called comfort temperature, members of both the case and the control households did not express feelings of being cold in the rooms.

7. 7. It is concluded, including the survey results from other literature, that improvements in the indoor thermal environment should receive more attention with respect of the reduction in stroke mortality, particularly in areas of cold climates.

Physiological and psychological thermal response to local cooling of human body

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.

Central thermosensitivity and the integrative responses of hypothalamic neurons

1. Hypothalamic thermosensitive neurons are important in the integrative regulation of body temperature. In addition to receiving afferent thermal input, their activity correlates with the stimulation of thermoregulatory mechanisms.

2. While cold sensitivity is synaptically mediated, warm sensitivity depends on inherent cellular responses. Warm sensitive neurons may also respond to other homeostatic variations, hormones, and endogenous mediators.

3. In contrast to peripheral thermoresponsiveness, which depends on conductance changes that regulate membrane potential, hypothalamic warm sensitivity relies on regulating the prepotential phase of the action potential.

4. Additionally, the recent morphologic characterization of these neurons supports the criterion for warm sensitivity.

Effect of hygroscopic fabrics on wear comfort in the fluctuating microclimate of clothing

1. 1. A new type of simulator for clothing microclimate was designed and constructed.

2. 2. The simulator was designed to simulate the humidity fluctuation of clothing microclimate as observed under light working conditions and to measure the surface temperature of sample fabrics against the skin by means of a radiation thermometer.

3. 3. Knitted fabrics of cotton and polyester, and polyethylene films were used as specimens with different hygroscopicities.

4. 4. The quick rise and fall in the surface temperature of cotton fabric was observed under rapid fluctuations of the microclimate humidity.

5. 5. Under the same humidity fluctuations, the temperature of polyester fabric rose and fell more moderately than that of cotton fabrics, and the temperature of the polyethylene film did not change. When the rate of change in stimulus temperature is higher, the threshold temperature of warm sensation of the skin comes closer to a given adaption temperature.

6. 6. Therefore, the rapid and large changes in the fabric temperature against the skin, which were observed especially for hygroscopic cotton fabric, must affect the thermal comfort of clothing.

Morphological and root carbohydrate responses of bald cypress to water level and water temperature regimes

1. 1. Reduced carbohydrate reserves have been suggested as a factor in the decline of bald cypress in swamp areas impacted by thermal effluents.

2. 2. Morphological characteristics and root carbohydrate concentrations were examined for bald cypress seedlings subjected to three temperature regimes (ambient, mid, and high) and three water levels (drained, saturated and flooded).

3. 3. Although few differences in total root carbohydrate concentrations existed after 3 weeks, the proportion of starch to sugar decreased with increasing temperature treatment.

4. 4. After senescence, mid saturated seedlings had the greatest aboveground and belowground biomass, whereas high flooded seedlings had the lowest concentration of root carbohydrates.

Influence of temperature changes on the ability of gangliosides to complex with Ca

1. 1.|The influence of temperature changes on Ca²⁺-binding to brain ganglioside mixtures of different polarity, to single gangliosides (G_M1, G_D1a, G_T1b) and to their deceramide was investigated potentiometrically by means of ion-selective electrodes.

2. 2.|Following cooling (3.5°C/min.) from 37 to 13°C the Ca²⁺-binding to gangliosides, except G_M1, was increased (7–30%).

3. 3.|Subsequent rewarming from 13 to 37°C resulted in up to 100% release of previously-bound Ca²⁺.

4. 4.|When comparing the maximal absolute binding difference of Ca²⁺ to gangliosides during temperature changes a decrease of these differences could be stated which corresponds to an increase in the polarity of the gangliosides.

5. 5.|From these experiments it is concluded that a higher polarity of neuronal gangliosides is responsible for a lower thermal sensitivity of Ca²⁺-binding to these compounds. This may be involved in the process of thermal adaptation of ectothermic vertebrates.

Transient response of the human-clothing system

1. 1. A transient clothing model which considers the effects of adsorption and thermal capacitance on the dynamic thermal response of clothing was developed.

2. 2. Moisture adsorption and desorption by the fabric are the major factors that affect the transient response of clothing.

3. 3. This moisture can come from evaporated sweat or from the environment.

4. 4. The clothing model was combined with a modified version of the two-node thermal model of the human body.

5. 5. The combined model shows that, during transients, the mix of latent and sensible heat flow from the skin may differ considerably from the corresponding heat flows from the clothing surface to the environment.

6. 6. The alteration of the heat flows can have a significant impact on the thermal response of the body by changing the sweat rate required to achieve the heat loss necessary to maintain thermal balance.