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Extracting operative temperatures from temperatures of physical models with thermal inertia.

Temperatures of operative temperature models, particularly those of thick-walled models of larger ectotherms, lag behind and are more restricted in range than the operative temperatures they estimate.Algorithms are provided to extract estimates of instantaneous operative temperatures from model temperatures.A simple deconvolution method can be used when wind speeds are constant.An iterative estimation method must be used when wind speed varies during the monitoring period.The iterative method is sensitive to measurement error, and so uses a smoothing filter to limit instabilities. The smoothing also limits the short-term fluctuations in the estimated operative temperature.Iterative estimates of operative temperature suggested time lags of up to 90 min between predicted operative temperatures and model temperatures for desert tortoises (mass=3 kg). Differences this large could affect estimates of time available for foraging.

Journal Article↗

[Temperature measurement in the ear canal: comparison of an infrared thermometer with conventional temperature probes and evaluation of clinical factors on infrared measurement].

PURPOSE: We compared the readings of the GENIUS 3000A FirstTemp infrared thermometer with a conventional temperature probe (MON-A-THERM tympanic) placed in contact with the tympanic membrane. We also systematically evaluated user-dependent factors influencing the infrared readings. METHODS: In 100 postoperative patients we investigated the repeatability of the infrared measurements and the agreement with tympanic thermocouple probes in the contralateral ear regarding the degree of auditory canal contamination. In 20 volunteers we evaluated the influence of three factors: interval between consecutive measurements, dwell time in the auditory canal before reading the temperature, and positioning of the grip. Finally, we compared the infrared readings in the same ear of 20 different users who were not familiar with this new method. RESULTS: Comparison with the tympanic contact probes revealed a mean difference of -0.67 degree C (+/-0.65 degree C 2 SD). The infrared thermometer significantly underestimated the temperature of the thermocouple probes. Repeatability was +/-0.3 degree C. The presence of cerumen in the auditory canal had no influence on the infrared readings. Shortening of the interval between two consecutive readings (30 and 60 s.) led to increasing differences between the two measurements with the second reading decreasing. After positioning the infrared thermometer in the auditory canal 5 seconds before taking temperatures, the recorded temperatures were significantly lower compared to the immediate temperature recordings. Rotation of the device out of the telephone handle position led to an increasing lack of agreement between infrared thermometry and thermistor probes. In 20 inexperienced operators agreement with the thermocouple probe was -0.80 degree C (+/-0.60 degree C 2 SD) and repeatability was +/-0.6 degree C. CONCLUSION: Although easy to use, infrared thermometry requires careful handling and experienced users. To get optimal recordings, the time between consecutive measurements should not be less than 90 seconds. Recordings should be taken immediately after positioning the device in the auditory canal. Best results are obtained when the grip of the device follows the ramus mandibulae like a telephone handle. The lower readings of the infrared thermometer compared to tympanic contact-probes indicate that the obtained readings represent the temperature of the auditory canal rather than of the tympanic membrane itself.

Ear Canal↗

Effect of growth temperature and temperature shifts on spinach leaf morphology and photosynthesis.

The growth kinetics of spinach plants (Spinacia oleracea L. cv Savoy) grown at 5 degrees C or 16 degrees C were determined to allow us to compare leaf tissues of the same developmental stage rather than chronological age. The second leaf pairs reached full expansion at a plant age of 32 and 92 days for the 16 degrees C and 5 degrees C plants, respectively. Growth at 5 degrees C resulted in an increased leaf area, dry weight, dry weight per area, and leaf thickness. Despite these changes, pigment content and composition, room temperature in vivo fluorescence, and apparent quantum yield and light-saturated rates of CO(2) exchange or O(2) evolution were not affected by the growth temperature. Furthermore, 5 degrees C expanded leaves were found to be more resistant to photoinhibition at 5 degrees C than were 16 degrees C expanded leaves. Thus, it is concluded that spinach grown at low temperature is not stressed. However, shifting spinach leaves from 5 degrees C to 16 degrees C or from 16 degrees C to 5 degrees C for 12 days after full leaf expansion had occurred resulted in a 20 to 25% reduction in apparent quantum yields and 50 to 60% reduction in light saturated rates of both CO(2) exchange and O(2) evolution. This was not accompanied by a change in the pigment content or composition or in the room temperature in vivo fluorescence. It appears that leaf aging during the temperature shift period can account for the reduction in photosynthesis. Comparison of cold-hardened and non-hardened winter rye (Secale cereale L. cv Muskateer) with spinach by in vivo fluorescence indicated that rye is more sensitive to both short term and longer duration temperature shifts than is spinach. Thus, susceptibility to an abrupt temperature shift appears to be species dependent.

Journal Article↗

Spectral airglow temperature imager (SATI): a ground-based instrument for the monitoring of mesosphere temperature.

The spectral airglow temperature imager is a two-channel, Fabry-Perot spectrometer with an annular field of view and a cooled CCD detector. The detected fringe pattern contains spectral information in the radial direction and azimuthal spatial information from the annular field of view. The instrument measures the rotational temperature from the O2 atmospheric (0,1) nightglow emission layer at 94 km and from the Q branch of the OH Meinel (6,2) band emission layer at 87 km. The method for temperature derivation is based on the temperature dependence of the line-emission rates. This dependence allows a determination of the temperature by a least-squares fit of the measured spectrum to a set of synthetic spectra, an approach that minimizes the effect of noise from the sky background and the detector. The spectral airglow temperature imager was developed to meet a need for monitoring the role of the mesosphere in climate variability through long-term observation of the mean temperature and the gravity waves from a single station, as well as large-scale wave perturbations through the use of multiple stations.

Journal Article↗

Temperature regulation of the testes of the bottlenose dolphin (Tursiops truncatus): evidence from colonic temperatures.

Dolphins possess a countercurrent heat exchanger that functions to cool their intra-abdominal testes. Spermatic arteries in the posterior abdomen are juxtaposed to veins returning cooled blood from the surfaces of the dorsal fin and flukes. A rectal probe housing a linear array of five copper-constantan thermocouples was designed to measure colonic temperatures simultaneously at positions anterior to, within, and posterior to the region of the colon flanked by the countercurrent heat exchanger. Colonic temperatures adjacent to the countercurrent heat exchanger were maximally 1.3 degrees C cooler than temperatures measured outside this region. Temporary heating and cooling of the dorsal fin and flukes affected temperatures at the countercurrent heat exchanger, but had little or no effect on temperatures posterior to its position. These measurements support the hypothesis that cooled blood is introduced into the deep abdominal cavity and functions specifically to regulate the temperature of arterial blood flow to the dolphin testes.

Animals↗

Temperature and endocrine activity during sleep in man. Activation of cortisol and thyroid-stimulating hormone, inhibition of human growth hormone secretion by raised or decreased ambient and body temperatures.

1. Polygraphic night sleep recordings in eight healthy male volunteers with simultaneous measurement of rectal temperature, plasma growth hormone (HGH), cortisol, and TSH concentrations were performed during normal, raised, and lowered ambient and body temperature. 2. There was a statistically significant increase in plasma cortisol and TSH levels during cold nights with a smaller rise during high temperatures. 3. Growth hormone levels, measured as the mean highest plasma concentration in the first two NREM-REM sleep cycles, were slightly lower during hot and cold nights than corresponding baseline values. It is suggested that there may be an inverse relation between ACTH and HGH secretion by the anterior pituitary gland. 4. During the nights of high ambient temperature, decreased total duration of sleep and particularly low values of paradoxical sleep were observed. Night sleep in low ambient temperature with a significant decrease of body temperature is not different from baseline conditions. 5. The results suggest that a pronounced increase in stress hormone secretion may occur without changes in polygraphic EEG criteria.

Adult↗

Complexity analysis of the temperature curve: new information from body temperature.

An attempt was made to develop a truly quantitative approach to temperature, based on models derived from nonlinear dynamics and chaos theory. Three different procedures for measuring the degree of complexity of the temperature curve were compared, and the possible correlations between these measurements and certain physiopathologically relevant parameters in healthy subjects were examined. Twenty-three healthy subjects (10 males, 13 females) between 18 and 85 years of age had their temperature measured every 10 min for at least 30 h. These time series were used to determine the approximate entropy (ApEn), a detrended fluctuation analysis (DFA), and the fractal dimension by the compass method (FD(c)). There was good correlation between the different methods of measuring the complexity of the curve [ r=-0.603 for ApEn vs. DFA ( p=0.002), r=0.438 for ApEn vs. FDc ( p=0.04) and r=-0.647 for DFA vs. FDc ( p=0.0008)]. Both the fractal dimension and the approximate entropy were inversely correlated with age [ r=-0.637 ( p=0.001) and r=-0.417 ( p=0.03), respectively], while the DFA increased with age ( r=0.413, p=0.04). The results thus suggest that complexity of the temperature curve decreases with age. The complexity of the temperature curve can be quantified in a consistent fashion. Age is associated with lower complexity of the temperature curve.

Adolescent↗

Time-temperature analysis of cell killing of BHK cells heated at temperatures in the range of 43.5 degrees C to 57.0 degrees C.

Baby hamster kidney (BHK) cells were heated at temperatures in the range of 43.5 degrees C to 57.0 degrees C to determine the time-temperature relationship of cell killing. The cells were grown on 0.025 mm thick pieces of mylar to minimize warm-up times. After heating, the cells were plated for the colony formation assay. The endpoints of 1%, 10%, or 90% isosurvival, or the D0 values of the survival curves were used to construct plots of the logarithm of the reciprocol of the exposure time versus the reciprocol of the absolute temperature. The data for each endpoint resulted in a straight line plot, indicating that the time-temperature relationship for cell killing remained constant from 43.5 degrees C to 57.0 degrees C; namely, a 1.8-fold increase in exposure time was required for a 1 degree C decrease in temperature in order to obtain isosurvival. Heated BHK cells were also examined using electron microscopy. The threshold level of altered morphology was the dissociation of polyribosomal structure and the formation of electron-dense granules within the mitochondria. The time-temperature relationship for the induction of this altered morphology was identical to that for the 90% isosurvival endpoint. Hence, the appearance of altered morphology appears to be related to cell killing.

Animals↗

Temperature regulation following nickel intoxication in the mouse: effect of ambient temperature.

1. The purpose of this study was to examine the interaction between ambient temperature (Ta) and the effects of nickel chloride on the thermoregulatory system of the mouse. 2. Male mice of the BALB/c strain were injected with nickel chloride at dosages of 0, 0.1, 1.0, 2.5, 5.0 and 10.0 mg/kg intraperitoneally and placed in an environmental chamber set at a Ta of either 10, 20, 30 or 35 degrees C for 60 min. Colonic temperature was then measured after one hour of exposure at a given Ta. 3. The thermoregulatory effects of nickel chloride were highly dependent on Ta. Nickel chloride had no effect on body temperature at Ta's of 30 and 35 degrees C. 4. 10 mg/kg dosage of nickel chloride caused a significant reduction in colonic temperature at a Ta of 20 degrees C. At a Ta of 10 degrees C the 5 and 10 mg/kg dosages of nickel chloride caused a significant lowering of body temperature. 5. Using segmented linear regression techniques it was shown that the threshold dose of nickel chloride for causing hypothermia was 9.6 and 3.3 mg/kg at Ta's of 20 and 10 degrees C, respectively. 6. This study has shown that two stressors, low Ta and nickel chloride intoxication, when applied independently have no effect on body temperature; however, when applied simultaneously, they have a significant toxic effect on thermoregulation.

Animals↗

In vitro infrared thermographic assessment of root surface temperatures generated by high-temperature thermoplasticized injectable gutta-percha obturation technique.

The aim of this in vitro study was to measure the temperature rises on the outer surface of roots produced by high-temperature thermoplasticized injectable gutta-percha technique. Thirty extracted human teeth with a single canal (15 maxillary central incisors and 15 mandibular central incisors) were used in this study. After root canal cleaning and shaping, the teeth were obturated with the injected gutta-percha heated to 160 degrees C (Obtura II). Temperature changes on the whole mesial outer surface of the roots was measured using an infrared thermal imaging camera. It showed that the use of gutta-percha heated to 160 degrees C to fill the maxillary central incisors and mandibular central incisors resulted in the rises of the root surface temperature by 8.5 degrees C and 22.1 degrees C, respectively. In conclusion, the injection of the gutta-percha heated to 160 degrees C into the root canal of maxillary central incisors produces temperature on the outer root surfaces below the theoretical critical level and, therefore, should not cause damage to supporting periradicular tissues. The injection of gutta-percha into the root canal space of the mandibular central incisors in vitro, resulted in an elevation of the root surface temperature by more than 10 degrees C.

Body Temperature↗

The effect of administered crystalloid fluid temperature on aural temperature of moderately and severely injured children.

OBJECTIVE: Warm intravenous fluid (W-IVF) administration is the standard of care to prevent hypothermia in injured adults. It is argued that such administration may not be helpful for treating injured children, because children often do not require as much intravenous fluid (i.v.f.) as adults. The purpose of this study was to compare the effects of W-i.v.f. to room temperature intravenous fluid (RT-i.v.f.) administration on aural temperature (Ta) in injured children during the first hour of trauma resuscitation. DESIGN: A randomized, controlled repeated-measures trial. SETTING: Emergency department, intensive care unit, and diagnostic areas in a level I pediatric trauma center. SAMPLE: Thirty moderately or severely injured children, ranging in age from 2 to 17 years (mean age = 8.9 years; SD = 4.4). METHODS: Eligible children were randomly assigned to receive either W-i.v.f. or RT-i.v.f. on ED arrival. Warmed IVF was administered with the Hotline fluid warmer (SIMS Level 1, Rockland, Mass). Aural temperatures were measured on arrival and every 10 minutes for 1 hour with a Core-Check Tympanic Thermometer (IVAC Medical Systems, San Diego, Calif). The level of significance for hypothesis testing was set at 0.05 (two-tailed). RESULTS: Groups were comparable in age, gender, weight, amount of infused i.v.f., Revised Trauma Score, room temperature, and baseline Ta. On average, Ta for the W-i.v.f. group increased by 0.25 degree C from baseline to final Ta, whereas Ta for the RT-i.v.f. group decreased by 0.32 degree C from baseline to final Ta. Repeated-measures analysis of covariance, treating baseline Ta as a covariate, demonstrated that Ta response profiles were similar (p = 0.06). CONCLUSIONS: When comparing the changes between baseline and final Ta for the W-i.v.f. and RT-i.v.f. groups, the standardized difference in temperature change was 0.62. Although results of the repeated measures analysis of covariance were not statistically significant, the standardized difference in temperature changes was large enough to warrant administration of W-i.v.f., even at slow flow rates, to prevent hypothermia in injured children.

Adolescent↗

Minimum growth temperatures of Hafnia alvei and other Enterobacteriaceae isolated from refrigerated meat determined with a temperature gradient incubator.

Minimum growth temperatures of Hafnia alvei (n = 156) and other Enterobacteriaceae isolates (n = 162) from refrigerated meat samples (n = 88) and control strains of H. alvei (n = 81) from clinical and environmental samples were determined with a plate-type continuous temperature gradient incubator on nutrient agar. The dominant species, Hafnia alvei and Serratia liquefaciens had mean minimum growth temperatures of 2.6 (range, 0.2-3.7 degrees C) and 1.7 (range, 0.2-2.6 degrees C), respectively. Values for other species included: Enterobacter agglomerans, 1.3 (0.7-1.7 degrees C); Escherichia coli, 8.7 (8.4-8.9); Escherichia vulneris, 1.6 (0.8-2.6 degrees C); and Serratia fonticola, 2.0 (1.1-3.0 degrees C). The H. alvei reference strains did not differ markedly from the meat isolates, with the exception of the diarrhoeagenic eae A positive strains (10.6, 10.2-11.5 degrees C). The representatives of H. alvei hybridization groups (HG) 1 and 2 did not differ in their minimum growth temperatures. The observed heterogeneity of the minimum growth temperatures of many Enterobacteriaceae species may be explained by limitations of the systems used for identification of enterobacteria, inadequacy of the Enterobacteriaceae taxonomy or true growth temperature heterogeneity within the various species.

Animals↗

Thermoregulation in rats exposed perinatally to dioxin: core temperature stability to altered ambient temperature, behavioral thermoregulation, and febrile response to lipopolysaccharide.

Recent studies have shown that perinatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) alters thermoregulatory function in adult rats and hamsters, indicated by a reduced body temperature during the animal's nocturnal phase. The present study was designed to assess the behavioral thermoregulation, ability to develop a fever, and thermoregulatory stability as a function of ambient temperature (Ta) in rats exposed perinatally to TCDD. Pregnant Long-Evans rats were exposed on gestational day (GD) 15 to 1 microg TCDD/kg (po). The male offspring were implanted with transmitters to monitor core temperature (Tc) and motor activity (MA). The 24-h pattern of core temperature was affected by TCDD exposure, characterized by a reduced nocturnal Tc. At some ages, the diurnal Tc of the TCDD group was elevated. This dysfunction in temperature regulation was most apparent at 7 and 11 mo of age. The 24-h pattern of MA was also altered by TCDD. The hypothermic effects of TCDD were most pronounced at cooler Ta values of 10 to 22 degrees C. In contrast, behavioral thermoregulation, assessed by measuring the selected Ta and Tc of rats in a temperature gradient, was unaffected by TCDD. The ability to develop a fever following administration of lipopolysaccharide (LPS) endotoxin (Escherichia coli; 50 microg/kg) was accentuated in the TCDD-treated animals. The data confirm a nocturnal hypothermia in rats prenatally exposed to TCDD. However, the normal behavioral regulation of Tc suggests that hypothalamic thermoregulatory centers are not permanently altered. The accentuated fever in TCDD animals shows possible functional alterations in the neuroimmune and/or thermoregulatory axes involved in fever.

Administration, Oral↗

The response in heat production, plasma catecholamines, and body temperature of burned rats to hypothalamic temperature displacement.

Rats, with the preoptic anterior hypothalamus implanted with two thermodes and a thermocouple reentry tube, had simultaneous direct and indirect calorimetry performed [during the ninth to eleventh postburn day interval] at ambient temperatures of 22 degrees and 28 degrees C. During calorimetry, blood was drawn at baseline and near the end of each period of displacement of the preoptic anterior hypothalamus temperature for catecholamine assay. Cooling the preoptic anterior hypothalamus resulted in a significant increase in heat production and plasma epinephrine and norepinephrine concentrations for both burn and control groups at 22 degrees C and 28 degrees C (p < 0.05 for all comparisons). Heat production demonstrated consistent negative linear correlation with preoptic anterior hypothalamic temperature. Plasma epinephrine values correlated with preoptic anterior hypothalamic temperature for only the controls at 28 degrees C ambient, whereas norepinephrine had significant linear correlation with heat production for all groups and significant negative linear correlation with preoptic anterior hypothalamic temperature. These data indicate norepinephrine may be more important than epinephrine in the maintenance of postburn hypermetabolism in this rat burn model while demonstrating that the hypermetabolism is appropriately responsive to perturbation of preoptic anterior hypothalamic temperature.

Animals↗

Reliability of urine temperature as a measurement of basal body temperature.

Natural family planning is based on the recognition of physiologic signs and symptoms that identify fertile and infertile phases of the menstrual cycle. Identification of the onset of the infertile period can be determined when the upward shift in basal body temperature (BBT) has occurred. A study was conducted to determine if the temperature of the first-morning voided urine adequately represents BBT. In 22 subjects, vaginal temperature, taken immediately upon awakening, was compared with first-morning voided urine temperature as measured continuously by thermocouples mounted in either of two flow-through devices attached to a toilet bowl. A significant correlation was found between the two temperatures. The convenience and hygiene of the method together with the reliability of urine temperature as an estimator of BBT could reduce the generally high rate of noncompliance of women choosing this natural method of family planning.

Adult↗

Acclimative response to temperature stress in higher plants: approaches of gene engineering for temperature tolerance.

Temperature stresses experienced by plants can be classified into three types: those occurring at (a) temperatures below freezing, (b) low temperatures above freezing, and (c) high temperatures. This review outlines how biological substances that are deeply related to these stresses, such as heat-shock proteins, glycinebetaine as a compatible solute, membrane lipids, etc., and also detoxifiers of active oxygen species, contribute to temperature stress tolerance in plants. Also presented here are the uses of genetic engineering techniques to improve the adaptability of plants to temperature stress by altering the levels and composition of these substances in the living organism. Finally, the future prospects for molecular breeding are discussed.

Adaptation, Physiological↗

Regulation of the peripheral body temperature by foods: a temperature decrease induced by the Japanese persimmon (kaki, Diospyros kaki).

We investigated whether the ingestion of the Japanese persimmon (kaki, Diospyros kaki) could lower the human peripheral body temperature. It was found that the temperatures recorded at the foot and wrist were depressed after kaki consumption compared to after the same amount of water consumption. The effects of ingesting freeze-dried kaki and eating a cookie (as its nutritional counterpart) containing the same amount of carbohydrate, protein, fat, and water were compared. A similar temperature-reducing effect of kaki was observed. The recovery of finger temperature after soaking the finger in ice-cooled water was also studied. The temperature recovery was delayed after kaki consumption. It was thus quantitatively demonstrated that ingesting kaki indeed had the effect of lowering (or repressing the rise) of the peripheral human body temperature, as has been traditionally believed in China for many hundreds of years.

Adult↗

Towards the estimation of three-dimensional temperature fields from noisy temperature measurements during hyperthermia.

The temperatures at most locations are unknown during clinical hyperthermia because temperature data are obtained at only a few discrete locations. In an attempt to further develop a technique for possibly solving this problem, the feasibility of using state and parameter estimation methods to predict three-dimensional temperature fields during hyperthermia treatments is investigated. Previous studies attempting to solve this problem have been limited to only one or two spatial dimensions. This paper investigates some conditions for which an estimation method can predict the complete three-dimensional temperature field for controlled numerical experiments with additive measurement noise. For the range of perfusion patterns considered, results show that the steady-state temperature field can be estimated to within 1 degree C if there is no measurement noise, no model mismatch, and as few as three measurement locations for seven perfusion zones. The addition of measurement noise degrades the performance of this estimation algorithm, especially when the number of measurement locations is small. Use of Tikhonov regularization of order zero significantly improves the performance of the algorithm for these cases. It was found that there is an optimal regularization parameter which maximizes the algorithm performance. This optimal value is a function of the perfusion magnitude and pattern. The present numerical results indicate that the approach used to solve this difficult and ill-posed problem could potentially be extended to estimate the complete temperature field in more realistic clinical conditions, but considerably more progress must be made before that goal can be reached.

Algorithms↗