Lamb birthweight in sheep differently acclimatized to a hot environment

1993 ◽  
Vol 44 (5) ◽  
pp. 933 ◽  
Author(s):  
GJ McCrabb ◽  
BJ McDonald ◽  
LM Hennoste
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Rectal Temperature ◽  
Northern Australia ◽  
Physiological Basis ◽  
Ambient Temperatures ◽  
Hot Environment ◽  
Hot Climate ◽  
The Difference ◽  
Semi Arid

Two groups of ewes were selected from a flock of 151 ewes in the semi-arid tropics of northern Australia, according to their rectal temperature measured at 1600 hours on each of 3 consecutive days when maximum daily ambient temperature was 36� 0.5�C. Low temperature status (LRT) ewes had a rectal temperature of <39.8�C at 1600 hours on each of the 3 days, while high temperature status (HRT) ewes had a rectal temperature of >39.9�C. These ewes were mated 8 months later and exposed to a summer gestation under normal grazing conditions. Maximum and minimum daily ambient temperatures during pregnancy were 37�0.3�C and 21�0.3�C respectively. Rectal temperature measured at both 0800 and 1600 hours for HRT ewes was higher (P < 0.01) than for LRT ewes during pregnancy. LRT ewes produced lambs of higher (P < 0.05) birthweight and ponderal index than HRT ewes. The physiological basis for the difference in fetal growth in ewes which respond differently to a hot climate has not been identified, but possible mechanisms are discussed.

The thermal response of sheep to a hot environment in different years

1995 ◽  
Vol 125 (1) ◽  
pp. 153-158 ◽  
Author(s):  
G. J. McCrabb ◽  
G. Bortolussi ◽  
L. M. Hennoste ◽  
B. J. McDonald
Keyword(s):  
Body Temperature ◽  
Rectal Temperature ◽  
Thermal Response ◽  
Daily Maximum ◽  
Northern Australia ◽  
Merino Sheep ◽  
Consecutive Measurement ◽  
Hot Environment ◽  
Maximum Temperatures ◽  
Semi Arid

SUMMARYThe aim of this experiment was to determine whether the thermal responses ofsheep exposed to a hot environment were similar in different years. Rectal temperaturesofsheep were measured during the hot months (between November and March) of three consecutive years (1990/91, 1991/92, 1992/93) in a flock of Merino sheep (n = 151) in the semi–arid tropics of northern Australia. Mean daily maximum temperatures in these months were 36±0·4, 39±0·3 and 37±0·3°C in Years 1, 2 and 3, respectively. In Year 1, rectal temperatures were measured on 3 consecutive days;the repeatability was 0·47 at 08·00 h and 0·64 at 16·00 h. In Year 1, two sub-groups were identified according to measurements of rectal temperature, low body temperature(LBT; n = 35) sheep, whose rectal temperature was ≤ 39·8°C at 16·00 h on each of the 3 consecutive measurement days, and high body temperature (HBT; n = 32) sheep, whose rectal temperature was ≥ 39·9°C. The rectal temperatures of LBT and HBT sheep were then measured during the subsequent 2 years. Rectal temperatures of HBT sheep were significantly higher than those of LBT sheep at both 08·00 and 16·00 h, in both Year 2 and Year 3. Rectal temperatures at 16·00 h in Year 1 were correlated (P < 0.001) with rectal temperatures at 16·00 h in both Year 2 (r = 0·79) and Year 3 (r = 0.82), respectively. It was concluded that measurement of rectal temperature in sheep exposed to a hot environment in any oneyear is an accurate index of their rectal temperatures during subsequent years.

scholarly journals Study on Wear and Fatigue Performance of Two Types of High-Speed Railway Wheel Materials at Different Ambient Temperatures

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1152
Author(s):  
Lei MA ◽  
Wenjian WANG ◽  
Jun GUO ◽  
Qiyue LIU
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
High Speed ◽  
Room Temperature ◽  
Lamellar Spacing ◽  
Wear Loss ◽  
High Speed Railway ◽  
Railway Wheel ◽  
Ambient Temperatures ◽  
Railway Wheels

The wear and fatigue behaviors of two newly developed types of high-speed railway wheel materials (named D1 and D2) were studied using the WR-1 wheel/rail rolling–sliding wear simulation device at high temperature (50 °C), room temperature (20 °C), and low temperature (−30 °C). The results showed that wear loss, surface hardening, and fatigue damage of the wheel and rail materials at high temperature (50 °C) and low temperature (−30 °C) were greater than at room temperature, showing the highest values at low temperature. With high Si and V content refining the pearlite lamellar spacing, D2 presented better resistance to wear and fatigue than D1. Generally, D2 wheel material appears more suitable for high-speed railway wheels.

Effects of restraint on rats exposed to high temperature

1959 ◽  
Vol 14 (6) ◽  
pp. 997-999 ◽  
Author(s):  
Harry M. Frankel
Keyword(s):  
High Temperature ◽  
Specific Gravity ◽  
Serum Calcium ◽  
Rectal Temperature ◽  
Serum Sodium ◽  
Serum Potassium ◽  
Male Rats ◽  
Ambient Temperatures ◽  
Exposure Temperature ◽  
Significant Difference

Male rats were placed in a cage either 8 in. x 8 in. x 10 in. (free) or 2 in. x 2 in. x 8 in. (restrained) and exposed to ambient temperatures between 40° and 60°C. ‘Restrained’ rats died sooner than ‘free’ animals at all temperatures. There was no significant difference between final rectal temperatures of free and restrained rats at ambient temperatures greater than 40°C; mean for these groups was 44.6°C. At 40°C the final rectal temperature was slightly lower in the restrained group (43.4° vs. 44.6°C). Restraint had no significant effect on the constituents of the blood examined. Serum potassium and specific gravity and blood hematocrits were increased and serum sodium was unchanged in heat-exposed rats compared with controls at 26°C. Serum calcium varied irregularly with exposure temperature. Submitted on December 23, 1958

Floral Induction in Growing Buds of Lychee (Litchi chinensis) and Mango (Mangifera indica)

1995 ◽  
Vol 22 (5) ◽  
pp. 783 ◽  
Author(s):  
DJ Batten ◽  
CA Mcconchie
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Low Temperatures ◽  
Floral Induction ◽  
Mangifera Indica ◽  
Litchi Chinensis ◽  
Ambient Temperatures ◽  
Potted Plants ◽  
Whole Process ◽  
Experimental Systems

Buds of potted plants of the terminal flowering tree species lychee (Litchi chinensis) and mango (Mangifera indica) forced to begin growth at high temperatures (florally non-inductive) and then transferred to low temperatures produced inflorescences, so the whole process of floral induction can occur in growing buds. Floral initials were visible in lychee within 39 days of transfer to low temperature and 30 days in mango, indicating that floral induction occurs relatively quickly in both species. In most cases where plants were transferred to winter ambient temperatures for floral induction, pre-activated (growing) buds flowered more consistently than buds that were dormant at the time of transfer. If the buds were small when plants were transferred from high temperature to low temperature, leafless inflorescences formed. If buds were a little larger, leafy inflorescences formed, with leaves basally and flowers terminally. If the buds were larger again, the shoots were purely vegetative. All these observations are consistent with floral induction occuning while the bud is growing and provide for much improved experimental systems for studying the physiology of floral induction in species such as lychee and mango.

Studies of the environmental physiology of tropical merinos

1978 ◽  
Vol 29 (1) ◽  
pp. 161 ◽  
Author(s):  
PS Hopkins ◽  
GI Knights ◽  
AS Le Feuvre
Keyword(s):  
Low Temperature ◽  
Rectal Temperature ◽  
Water Loss ◽  
Heat Dissipation ◽  
Evaporative Water Loss ◽  
Compensatory Mechanisms ◽  
Evaporative Water ◽  
Ambient Temperatures ◽  
Diurnal Patterns ◽  
Made In

Rectal temperature measurements of tropical Merino sheep taken in the sun during summer indicated that there were high and low temperature groups. Animals of low temperature status (e.g. 39.4°C) also exhibited a low respiration rate (e.g. 110/min) in comparison with their less adapted counterparts (40.0° and 190/min). These differences were greatest when ambient temperatures were high. The repeatability of temperature status was 0.46 (P < 0.01). Animals of folds (+) phenotype had significantly higher rectal temperatures than folds (–) animals (P < 0.05). Shearing caused a marked but transient increase in rectal temperature. Compensatory mechanisms apparently involved an increase in cutaneous heat dissipation and/or a decrease in exogenous heat load. Evaporative water loss (80–115 ml/kg/day) greatly exceeded the non-evaporative water loss (40–65 ml/kg/day) of sheep in metabolism cages. Respiratory water loss could account for only 8–10% of the total daily evaporative water loss. Non-respiratory evaporative water loss (as measured by difference) was c. 75–100 ml/kg/day. There were no striking differences between high and low temperature status sheep in this regard. Measurements of respiratory (2 ml/kg/hr) and non-respiratory (5.5 ml/kg/hr) evaporative water loss made in hygrometric tents suggested that the greater non-respiratory water loss was partly due to a higher rate of loss and partly to a longer period of loss per day. This suggestion was supported by the diurnal patterns of rectal temperatures and respiration rates reported here, though no firm conclusions could be made as to the thermotaxic effect of non-respiratory water loss and thermoregulation of tropical Merinos with varying amounts of wool cover.

PHENOTYPIC AND YIELD RESPONSES OF IRRIGATED GROUNDNUT CULTIVARS IN A HOT ENVIRONMENT

2000 ◽  
Vol 36 (3) ◽  
pp. 303-312 ◽  
Author(s):  
HASSAN M. ISHAG
Keyword(s):  
High Temperature ◽  
Elevated Temperatures ◽  
Kernel Size ◽  
Growth Ratio ◽  
Yield Increase ◽  
Hot Environment ◽  
Stable Yield ◽  
Yield Responses ◽  
Maximum Air Temperature ◽  
Semi Arid

High temperature is a major problem in groundnut (Arachis hypogaea) producing areas of arid and semi-arid tropics whether rainfed or irrigated. Knowledge of the maximum air temperature that plants can tolerate will help in selecting genotypes adapted to high temperature. The objectives of this study were to evaluate the growth, development, yield and yield components of different groundnut genotypes grown under elevated temperatures. Five groundnut cultivars and lines were grown in the field from 1984 to 1986 in Vertisols. Measurements on flowering, growth and development were carried out frequently. Thermal units required for groundnut cultivars to reach maturity were 2247 °C days. Larger kernel size, higher pod:total growth ratio and longer pod-filling period were the most important parameters for yield increase in heat-stressed environments. Early Bunch gave a stable yield across environments and was found to be more tolerant of high temperature. Cultivars differed in their pod:total growth ratio and Early Bunch had the highest ratio.

The Difference in Optics Between Volcanic and Plutonic Plagioclases, and its Bearing on the Granite Problem

1952 ◽  
Vol 89 (4) ◽  
pp. 233-250 ◽  
Author(s):  
Doris L. Reynolds
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Low Temperatures ◽  
Metamorphic Rock ◽  
Alkali Feldspar ◽  
Optical Indicatrix ◽  
Quartz Porphyry ◽  
The Real ◽  
Magmatic Rocks ◽  
The Difference

AbstractThe orientation of the optical indicatrix in synthetic and volcanic plagioclases differs from that in plutonic and metamorphic plagioclases, the former “optics” being commonly known as “high-temperature”, and the latter as “low-temperature”. The difference between the two series is most marked at the sodic end and decreases towards An70. The conclusion that the difference, though small, still persists in the range An70 to An100 is shown to be unwarranted on the evidence available. Grave doubt is thrown on the supposition that temperature is the controlling factor in determining the type of optics by Tuttle and Bowen's failure to synthesize low-temperature albite, even at low temperatures. It is known, however, that some low-temperature plagioclases (e.g. in albite-schists) have grown without the intervention of melt. The real antithesis may therefore be between plagioclases crystallized from melts, and those developed during the metamorphic reconstitution of rocks.From the fact that the plagioclase, quartz, and alkali feldspar of undoubted magmatic rocks such as quartz-porphyry and rhyolite are respectively systematically different from those of granite it is concluded that the latter is a metamorphic rock

Testing a device for starting an internal combustion engine at low temperature and prospects for its application

2021 ◽  
pp. 25-30
Author(s):  
Keyword(s):  
Experimental Data ◽  
High Temperature ◽  
Low Temperature ◽  
Internal Combustion Engine ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Engine Compartment ◽  
Ambient Temperatures

The starting of the internal combustion engine in conditions of low and critically low ambient temperatures is considered. It is shown that a successful start of an internal combustion engine can be ensured by creating a fuel-air mixture with a high temperature outside the engine compartment. The design of a device for creating such mixture and research experimental data are presented. A new scheme of the starting device is proposed, which can be integrated into various types of internal combustion engines. Keywords: internal combustion engine, starting, low temperature, operation. [email protected]

scholarly journals A Compressive Review on High- and Low-Temperature Performance of Asphalt Modified with Nanomodifier

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Limin Li ◽  
Lingming Yang ◽  
Yuliang Lin ◽  
Xiancai Zhang
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Asphalt Binder ◽  
Systematic Investigation ◽  
Nanoparticle Size ◽  
Asphalt Binders ◽  
Temperature Performance ◽  
Low Temperature Performance ◽  
The Difference ◽  
Low Performance

At present, rutting and cracking have become serious issues in asphalt pavement, especially in the areas of summer heat and winter cold. Nanomodifier has been widely used in recent years due to its unique properties in improving the characteristics of asphalt binders. To make better use of nanomodifier to solve the problem of rutting and cracking of pavement, a compressive review on the high- and low-temperature performance of nanomodified asphalt is performed. The results indicate that for high- and low-temperature performance of asphalt binder, the effectiveness of nanomodification is found to be strictly influenced by the combination of original asphalt type, nanomodifier type, nanomodifier dosage, nanoparticle size, and preparation of nanomodified asphalt, and the high-temperature antirutting performance and low-temperature crack resistance of final blends are various with the combination. Chemical composition, microstructure, dispersion, and compatibility of final blends were the possible reason causing the difference. The rational selection of the combination can improve the high-temperature rutting resistance and the low-temperature cracking resistance of asphalt binder. So far, there is a lack of systematic investigation in this regard. Therefore, it is very necessary to study systematically the original asphalt, nanomodifier, nanomodifier dosage, nanoparticle size, and preparation of nanomodified asphalt effect on the high and low performance of nanomodified asphalt, especially in the modification mechanism in the future.

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