Temperature Decrement Research Articles

Effects of Light Source, Ambient Temperature, and Dietary Energy Source on the General Performance and Incidence of Leg Abnormalities of Roaster Chickens

A 2 × 3 × 4 factorial experiment was designed to test the effects of two light sources (incandescent vs. fluorescent), three weekly ambient temperature decrements of 4.5, 3.0, or 1.5 C (from 34.5 to 20 C), and four dietary energy regimens on the general performance and incidence of leg abnormalities of roaster chickens.Light source had no significant effect on mortality, body weight, or feed conversion. Incidence of angular deformity (AD) and total leg abnormalities (TLA) was lower and tibial dyschondroplasia (TD) was higher (P<.05) for roasters reared under fluorescent as opposed to incandescent light. Cooler ambient rearing temperatures increased (linearly) the incidence of mortality, curly toes (CT), AD, enlarged hocks (EH), and TLA but resulted in a linear decrease in TD and had a detrimental (linear) effect on feed conversion. Dietary energy had no significant effect (P>.05) on mortality or leg abnormalities except for CT, (wherein there was decreased incidence with increasing dietary energy) or final live weight, but overall (to 70 days) increasing dietary energy resulted in a linear improvement in feed conversion.Mean monetary returns were nonsignificantly better for roasters reared under fluorescent vs. incandescent light (ca 8¢/bird) and were better for birds reared under warm versus cool ambient temperatures (ca 10¢/bird). Increasing dietary energy resulted in a linear increase in monetary returns.

A search for the Sunyaev-Zeldovich effect at millimetre wavelengths

The Sunyaev–Zeldovich effect is potentially a powerful tool for observational cosmology. We report the results of the first attempt to detect this small effect at a wavelength of 1.15 mm. At this wavelength the effect has a sign opposite to that at the longer wavelengths previously employed in such studies. Observational data on two clusters, 0016+ 16 and Abell 478, are described. Particular attention has been devoted to the position-dependent offsets which are characteristic of these observations. We analyse the spurious systematic contribution such an offset adds to the Sunyaev–Zeldovich signal, and we demonstrate that, provided that chopping and nodding are performed in hour angle, this contribution can be precisely measured from the baseline drift. These analytical techniques have been applied to 16 hr of observational data on these two clusters. We achieved a marginal detection of the effect corresponding to a temperature decrement in the Rayleigh–Jeans region of ΔTRJ=−1.6±1.0mK for the cluster 0016+16 and an upper limit of ΔTRJ=−0.2±1.0mK for the cluster Abell 478.

Cooling Dairy Cattle by a Combination of Sprinkling and Forced Ventilation and Its Implementation in the Shelter System

A method for cooling dairy cattle based on repeated wetting to attain maximal water trapping in the coat, followed by its rapid evaporation by using forced ventilation has been examined. Effects examined include duration of wetting, duration of cooling, and density of the animals in the holding area. The coat was wetted by inverted static sprinklers. Also examined was the extent to which the diurnal increase in rectal temperature can be prevented. The maximal decrement of temperature was attained at 30min after cessation of cooling in all trials. Wetting the coat for 10s was less effective than for 20 or 30s; the latter did not differ in their effects. Cooling animals for 15, 30, and 45min produced decrements in temperature of .6, .7, and 1.0°C, respectively. Maintaining animals at a density of 1.9m2/ cow in the holding area reduced to about half the decrement as compared with a density of 3.5m2/cow. When cows were cooled 5 times per day for 30min, temperatures were maintained within 38.2 to 38.9°C during the day, which were significantly lower than for those not cooled.

Cooling-rate dependence for the spin-glass ground-state energy: Implications for optimization by simulated annealing.

The zero-temperature ground-state properties of five spin-glass models have been studied as a function of the cooling rate $r=\frac{\ensuremath{-}\ensuremath{\Delta}T}{t}$. Here $\ensuremath{\Delta}T$ is the temperature decrement and $t$ is the time (in Monte Carlo steps) at each temperature $T$. For the 2D $\ifmmode\pm\else\textpm\fi{}J$ and Gaussian models, $E(r)={E}_{0}+{C}_{1}{r}^{x}$, where $x\ensuremath{\cong}0.25$, while for the 3D $\ifmmode\pm\else\textpm\fi{}J$, a two-layer $\ifmmode\pm\else\textpm\fi{}J$, and infinite-range models, $E(r)={E}_{0}\ensuremath{-}{C}_{2}{(\mathrm{inr})}^{\ensuremath{-}1}$. We speculate that this difference is related to the fact that the 2D models are not $\mathrm{NP}$-complete while the other three models are.

Metabolic depression and heat balance in starving Wistar rats

1. 1. Resting metabolic rate and heat balance was studied in rats starved for 8 days at ambient temperature 22°C and 30°C. 2. 2. A depression of the resting metabolic rate was observed, at both temperatures. Metabolic rate depression, expressed as a function of the ratio between the real body wt and the normal body wt, was less at 22°C than at 30°C. 3. 3. Deep body temperature decrements of 2°C and 0.6°C by the end of starvation indicated that central temperature controlling mechanisms were affected. 4. 4. Concurrent decrements of evaporative heat loss did not account for the changes in heat conductance, thus indicating that a reduction of peripheral blood circulation also took part.

Seasonal Effects on the Relationships between Morphological Characteristics and Decrement of Rectal Temperature in Cold Environment

The purpose of this study is to examine whether there is seasonal effects on the relationships between some morphological measurments and decrement of rectal temperature in a cold environment. Nine male subjects who wore thin shirts and shorts were exposed to 12iC with relative humidity of 50% for 60minutes. The experments were perforrned in Summer and in Winter. The relative large decrement of rectal temperature during the last 30 minutes of exposure to a cold air were observed only in relative lean subjects in Summer, but not in all in Winter. The decrement of rectal temperature was more affected in Summer by the variations of body fat per cent and body surface area per unit body volume. However, metabolic response to a cold air was more affected in Winter by the variations of the above two parameters. It was concluded that morphological factors were related intimately to heat loss by which rectal temperature was decreased in Summer and to heat production by which rectal temperature was maintained in Winter in a cold environment. Therefore, it was thought that an index as a cold tolerance such as lower critical temperature was more related to morphological factors in Winter than in Summer.

Effect of hypothermia on changes in high-energy phosphate production and utilization in total ischemia

The effect of temperature on the rate of production, utilization and destruction of high-energy phosphate in total ischemia was investigated in the dog heart. These studies were performed utilizing a new model of ischemic injury which was designed to test the effect of interventions on the metabolism and structure of ischemic myocardium. In this model, the normal heart was isolated from the circulation in vivo and was arrested immediately with hyperkalemic, oxygenated, autogenous arterial blood prior to the induction of total ischemia. Left ventricular pressure changes in the isolated heart were used to time the onset of ATP depletion to the levels associated with the development of contracture-rigor. Decrements in temperature progressively slowed both ATP production from anaerobic glycolysis and ATP utilization and delayed but did not prevent ATP depletion and the onset of contracture-rigor. Reserve supplies of high-energy phosphates were utilized and much of the adenine nucleotide pool was destroyed at all temperatures studied. Anaerobic glycolysis provided more than 80% of the high-energy phosphates utilized by the ischemic cell at all temperatures but always ceased when ATP levels decreased to 1–2% of control. The results demonstrate that the protective effect of hypothermia in total ischemia is due to a proportional slowing in rates of energy production and utilization. Consequently, hypothermia only delays the depletion of the high-energy phosphate reserves of the myocyte and the destruction of the adenine nucleotide pool.

Role of hypothermia in the production of gastric ulcers in a rat spinal cord transection model.

An association between hypothermia and gastric ulceration has been reported in rats in cervical cord section and in restraint models. The present study was designed to determine this relationship in cervical and in lumbar cord sectioned Sprague-Dawley rats. Ambient temperatures were varied by placing the sectioned animals in a room-temperature (23 degrees), incubator (28 degrees), or cold-room (4 degrees) environment for 8 hr. Rectal temperatures were recorded at the beginning and end of all experimental conditions. The endpoint of each study was the presence or absence of ulcers on naked eye examination. The length of each ulcer was measured and the lengths were totaled for each stomach. Cervical section rats became hypothermic at room temperature and developed extensive linear ulcerations of the glandular stomachs. A warm environment reduced both the decrement in core temperature and the degree of ulceration. Lumbar section rats only became hypothermic when exposed to cold and then developed significant ulcers. Hypothermia plays an important role in ulcerogenesis, but other factors are also important since not all the hypothermic rats developed ulcers and exposure of sham-operated rats to cold led to occasional pinpoint ulcer formation in spite of maintenance of a stable core temperature.

5-Thio-D-glucose: hypothermic responses in mice.

Adult male mice were administered several doses of 5-thio-D-glucose (5-TG) at two environmental temperatures, 4 and 22 degrees C. Both intracerebroventricular (icv) and intraperitoneal (ip) administration of 5-TG resulted in significant (P < 0.05 to P < 0.001) decrements in rectal temperature (Tre) that were dose dependent. After 30 min, the hypothermic effects were significantly (P < 0.001, icv, 100 microgram) exacerbated by cold exposure (4 vs. 22 degrees C) and were likewise intensified significantly (P < 0.005, 45 min, fed vs. 18 h fasted) by food deprivation. These reductions in Tre were accompanied by significant (P < 0.001) increases in circulating levels of glucose. The present results indicate that 5-TG may be eliciting both central and peripheral cellular glucopenia concomitant with circulatory hyperglycemia; thus, the resultant hypothermia may be arising from competitive inhibition of glycolysis by 5-TG intermediates as well as reduced availability of tissue glucose.

Microwave search for ionized gas in clusters of galaxies

Using the 11-meter NRAO/sup 3/ telescope at lambda=9 mm, we have examined 16 clusters of galaxies for evidence of a change in temperature of the cosmic microwave background radiation which might be produced by inverse Compton scattering by electrons in hot intergalactic gas. For 15 of the clusters, no significant evidence of the effect was found at a level of sensitivity comparable to other published studies. In particular we do not confirm the effect reported for Abell 2218. We do detect a significant temperature decrement in Abell 576.

History dependent creep of Ti-6Al-4V alloy

AbstractThe purpose of this short communication is to report the interesting observation that the steady state creep rate (SSCR) of, Ti-6Al-4V alloy is history dependent. Temperature increment tests yield different results from temperature decrement tests.

Bilateral spatial summation of cooling of symmetrical sites

The possibility of spatial summation of conducted −‡Ts (temperature decrements from the adapted skin temperature) was tested when the −‡Ts were presented simultaneously and individually at symmetrical sites on either side of the body. The use of a signal detection rating method yielded data that indicate that spatial summation is complete (area and intensity trade reciprocally) for −‡s near threshold and at clearly suprathreshold intensities of stimulation is invariant of the adapted skin temperature (AT), and the intensity of stimulation within the range of stimuli used (from as little as −0.05‡C to as much as −1.25‡C). In view of the characteristics ascribed to the thermosensory apparatus in humans, it is postulated that spatial summation occurs in the central nervous system.

1—PARAMETER ESTIMATION FOR THE DYNAMIC MECHANICAL TESTING OF YARNS

In order to derive the dynamic mechanical properties of yarns as a function of temperature, the frequency and logarithmic decrement of the damped free vibration of the yarn must be determined. By using samples of the measured vibration, a mini-computer estimates the frequency from the zero crossings and the decrement from a combination of all the samples of the signal, instead of only the peak amplitudes. This new method is based on the simple truth that: sin2θ + cos2θ = 1.

Rhesus monkey (Macaca mulatta) cool sensitivity measured by a signal detection method

Two rhesus monkeys were trained to detect cool stimuli (decrements in skin temperature from the adapted temperature) presented to the palm of the left hand after the skin had been preadapted to a 33°C temperature. The procedure was analogous to the signal detection “yes-no” method used with human observers. Receiver operating characteristic curves were generated by varying the a priori probability of stimulus oecurrence. The proportion of hits and of false alarms increased with increases in the a priori probability of stimulation. The points of isosensitivity of both subjects for cool intensities of 0.3°C, but not at greater intensities, yielded straight lines with slopes of approximately one when plotted on normal-normal coordinates. The values of the d’s detectability index decreased from 3.52 to 0.75 for one subject and from 2.81 1to 1.28 for the other as the stimulus intensity was decreased from 0.8° to 0.15° cooling from the adapting temperature. Cool thresholds for each subject of 0.19° and 0.12°C were computed from classical psychometric functions when threshold was defined as 50% hits at a 50% probability of stimulus occurrence. These thresholds are comparable to published reports of the cool threshold for the rhesus.

HYPOTHERMIC EFFECT OF SODIUM ACETYLSALICYLATE ON AFEBRILE MONKEYS

1 Afebrile monkeys (Macaca cyclopis) receiving systemic (100-300 mg/kg, i.p.) or central (5-20 mg into the 3rd cerebral ventricle) administration of sodium acetylsalicylate showed a dose-dependent reduction in rectal temperature in a thermoneutral environment (25 degrees C).2 Administration of sodium acetylsalicylate (10 mg) into the 3rd cerebral ventricle produced a hypothermia with a temperature decrement of 1.0 degrees C, ehile an intraperitoneal injection of 300 mg/kg was required for a temperature decrement of 0.9 degrees C. The ratio between the total doses given by the two toutes was 1 to 120.3 Following the administration of sodium acetylsalicylate, a decline in rectal temperature was accompanied by a tail cutaneous vasodilatation.4 The data suggest that sodium acetylsalicylate can lower the normal body temperature by activating heat loss or decreasing the normal (tonic) inhibition of the heat loss mechanism via the central nervous system.

Intracellular recording during focal hypothermia in cat pericruciate cortex

Intracellular records were obtained from both glia and neurons in cat pericruciate cortex during focal hypothermia induced by a Peltier device. Glial membrane potential varied inversely and linearly with temperature. For 28 glia, the mean depolarization was 16.8 ± 7.0 mv for a temperature decrement of 5–6 C. Glial input resistance varied inversely and reversibly with temperature with a Q 10 of 2.5. Neuronal membrane initially hyperpolarized 4.5 ± 3.3 mv until 3 min after the temperature decreased below 30 C. At that temperature and time a plateau depolarization occurred with a magnitude of 14.7 ± 5.5 mv. During rewarming, the membrane again hyperpolarized 5.9 ± 4.0 mv with return to precool values on complete rewarming. Action potential firing patterns also changed with hypothermia. The regular firing pattern was supplanted by a doublet, triplet, and quadruplet mode during the period of initial hyperpolarization. Tonic firing occurred on the upramp of the plateau depolarization and the multiple spike mode returned during the postcool hyperpolarization. Models are proposed to explain the glial depolarization with hypothermia as a result of decreased glial NaK pumping with a resultant increase in extracellular K. Neuronal hyperpolarization was a result of accelerated electrogenic NaK pumping in response to the increasing extracellular K. The tendency to the multiple spike mode is explained as a result of quantitative differences in somatic-dendritic interactions.

Intracellular recording during focal hypothermia of penicillin and alumina experimental epileptic foci

Intracellular records were obtained from penicillin and alumina experimental epileptic foci. The membrane of glia and neurons in the penicillin focus depolarized significantly more than those in normal cortex (20). The firing pattern of neurons in penicillin foci changed markedly with small temperature decrements. The depolarization shiffs and surface EEG spikes ceased at 33-32 C, returning as the cells were rewarmed. In the alumina focus, glial depolarization was the same as that of normal cortex. Neuronal membrane, in the alumina focus, followed the same pattern as that of normal cortex with initial hyperpolarization, plateau depolarization, postcool hyper-polarization, and return to precool levels. Action potential duration increased significantly greater than that in normal cortex with the rising phase more prolonged in the penicillin focus and the falling phase more prolonged in the alumina focus. Models are proposed to explain the observed behavior as impaired passive Na flux and impaired active NaK pumping in the penicillin focus. Impaired K flux and a greater magnitude of electrogenic NaK pumping are the neuronal membrane abnormalities in the alumina focus. These experimental foci, thus, contain “epileptic” cells with intrinsic membrane abnormalities, but the nature of the membrane abnormality is different in the two models.

Near Infrared Spectra of Water in Aqueous Solutions of Organic Salts. A Solvation Study of Bu4NBr, , and

The near-infrared spectrum of water at various temperatures and in aqueous solutions of Bu4NBr, [Formula: see text], and [Formula: see text] is studied in the region 0.8–1.2 µ. The spectra are recorded differentially with respect to water by varying the cell lengths as to take into account density changes or the volume occupied by the solutes. A simple analysis of these spectra illustrates the qualitative similarity between the effects of the Bu4N+ ion and that of a temperature decrement on the spectrum of water. On the other hand striking differences are observed in the differential spectra obtained with Bu4NBr and the phenyl substituted: salts. Further differences are exhibited in the relative solute-solvent interactions of [Formula: see text] and [Formula: see text].

Temperature regulation of Eskimos, Indians, and Caucasians in a bath calorimeter

Eighteen men: six Alaskan Eskimos, six Arctic Athapascan Indians, and six Caucasian U. S. soldiers were immersed serially in a bath calorimeter where the rates of heat production and loss were measured during whole-body exposure to water temperatures of 35, 33, and 30.5 C. At each of these temperatures the Eskimos exhibited the highest rates of heat production and loss, followed by the Indians and Caucasians in decreasing order. Duplicate basal metabolic rate measurements averaged 46 kcal/hr m2 in the Eskimos, 42.5 kcal/hr m2 in the Indians, and about 37 kcal/hr m2 in the Caucasians. Body fat percentages calculated by the skin-fold method were: Eskimos, 6.6%; Indians, 12.3%; and Caucasians, 15.6%. Calculations showed the Eskimos had the lowest tissue insulation followed, respectively, by the Indians and Caucasians. Calculations showed the lower insulation in the Eskimos was independent of their lack of body fat and probably reflected a greater peripheral blood flow. Since the rectal temperature decrements during immersion were the same in all three groups, it was concluded that the surface temperature gradients extended more deeply in the Eskimos than in the other two groups. Hence, they could be described as having smaller “cores” and larger “shells” than either the Indians or the Caucasians. Submitted on August 27, 1962d

EXPONENTIAL TRANSFER AND DIFFUSION

The one-dimensional heat equation is solved for exponentially decaying rate of increment and decrement of temperature at the surface of a semi-infinite medium.The diffusion equation is solved for exponentially decaying rate of transfer from a source to a diffusion medium. The two types of sources are: mass initially (a) located at a point, and (b) distributed at interfaces within a porous rectangular parallelepiped or sphere. Solutions for subsequent concentration distribution are stated, and compared with the well-known cases of instantaneous transfer. Numerical evaluation is afforded by the probability integral of complex argument. The treatment is applicable to cases of first-order irreversible chemical reaction and simultaneous diffusion of reaction products.