Effect of prolonged exposure to continuous heat and humidity similar to long haul live export voyages in Merino wethers

2011 ◽  
Vol 51 (2) ◽  
pp. 135 ◽  
Author(s):  
C. A. Stockman ◽  
A. L. Barnes ◽  
S. K. Maloney ◽  
E. Taylor ◽  
M. McCarthy ◽  
...  
Keyword(s):  
Prolonged Exposure ◽  
Physiological Responses ◽  
Heat Exposure ◽  
High Heat ◽  
Controlled Environment ◽  
Physiological Changes ◽  
Bicarbonate Concentration ◽  
The Core ◽  
Continuous Heat ◽  
Live Export

This experiment investigated the physiological responses of Merino wethers (n = 12) to prolonged high heat and humidity similar to that experienced during long haul, live export voyages from Australia to the Middle East. Merino wethers were randomly assigned to individual pens in rooms with a controlled environment, and exposed to gradually increasing temperatures, and two exposures of 3–4 days of sustained high heat and humidity, up to a maximum of 31°C wet bulb temperature (37°C dry bulb and 67% relative humidity). There was 1 day at thermoneutral temperatures separating the heat exposures. The core temperatures and respiratory rates of Merino wethers increased during both heat exposures, with open-mouthed panting observed during both exposures. Plasma partial pressure carbon dioxide (pCO2) and bicarbonate concentration (HCO3–) decreased, and plasma pH increased during the second heat exposure. Both pCO2 and HCO3– returned to normal immediately following the heat exposures. Feed intake was maintained during the heat exposures. There were no large alterations in blood electrolyte concentrations attributable to the effects of the heat. The results show that Merino wethers experienced significant physiological changes during exposure to prolonged and continuous high heat and humidity, but maintained most aspects of homeostasis despite being hyperthermic and recovered quickly when conditions returned to thermoneutral.

Acclimation of rats following stepwise or direct exposure to heat

1985 ◽  
Vol 59 (2) ◽  
pp. 408-412 ◽  
Author(s):  
A. R. Gwosdow ◽  
E. L. Besch ◽  
C. L. Chen
Keyword(s):  
Water Intake ◽  
Elevated Temperatures ◽  
Plasma Corticosterone ◽  
Male Rats ◽  
Controlled Environment ◽  
Physiological Changes ◽  
Evaporative Water ◽  
Initial Exposure ◽  
Direct Exposure ◽  
Food And Water Intake

The physiological changes in male rats during acclimation were studied following direct or stepwise exposure to heat (32.5 degrees C) in a controlled-environment room. The animals were exposed to each temperature for 10 days beginning at 24.5 degrees C and returning to 24.5 degrees C in the reverse order of initial exposure. Relative humidity of 50 +/- 2% and a 12-h light-dark photoperiod (light from 0900 to 2100 h) were maintained. Physiological changes in metabolic rate (MR), evaporative water loss (EWL), plasma corticosterone, body water turnover, and food and water intake were measured. The results indicate a significantly (P less than 0.001) elevated plasma corticosterone and MR in rats exposed directly to heat from control temperature (24.5 degrees C) but not in those animals exposed stepwise via 29.0 degrees C. All kinetic parameters of water pool changed (P less than 0.01) on direct exposure to heat, whereas rats exposed in a stepwise manner increased only pool turnover. In addition, exposure to experimental temperatures resulted in reduced (P less than 0.05) relative food intake and increased (P less than 0.05) water intake. Compared with the control condition of 24.5 degrees C, EWL was significantly (P less than 0.05) elevated when the animals were exposed either directly or in a stepwise fashion to 32.5 degrees C. These data suggest that the response to elevated temperatures is influenced by the temperature to which the rat is acclimated.

Ageing of climbing ropes with and without hydrophobic coating

2021 ◽  
pp. 175433712110628
Author(s):  
Daniel Sedláček ◽  
Martina Roso ◽  
Leano Viel ◽  
Nicola Perotto ◽  
Barnaby Caven ◽  
...  
Keyword(s):  
Prolonged Exposure ◽  
Radial Pressure ◽  
Polyamide 6 ◽  
Drop Test ◽  
Maximum Force ◽  
Breaking Force ◽  
Hydrophobic Coating ◽  
The Core ◽  
Negative Effect ◽  
Static Tensile

The effects of 4 months of weather exposure on the ageing of dynamic climbing ropes made of polyamide 6 were studied and differences between ropes with and without hydrophobic coating were examined. The polyamide degradation of the rope yarns was studied using infrared spectroscopy and a quasi-static tensile test. The number of falls to failure and the maximum force on the climber in a fall were evaluated with a drop test according to the UIAA 101 standard. Moreover, changes in the length of the ropes due to weathering were measured. The following results were found. After 4 months of weathering, sheath yarns of the coated rope showed a greater decrease in breaking force than those of the uncoated rope, which might be due to reactions of polyamide with radicals formed during the photo-induced oxidation of the coating. In contrast, the core yarns from the uncoated rope showed a greater decrease in breaking force than those from the coated rope, probably due to prolonged exposure of the uncoated core to water with possibly dissolved atmospheric acids. Furthermore, the decrease in the number of falls to failure was greater in the uncoated than in the coated rope. This difference was explained by a mechanism of changes in radial pressure of the sheath on the core. Regarding the maximum force on the climber, no significant changes due to ageing were observed during the drop test. Thus, it was concluded that 4 months of weather exposure do not pose a safety risk for climbing ropes, but the negative effect of coating on the ageing of polyamide might be detrimental when it comes to static personal safety equipment, such as slings or accessory cords.

Towards understanding the neural origins of hibernation

2022 ◽  
Vol 225 (1) ◽  
Author(s):  
Madeleine S. Junkins ◽  
Sviatoslav N. Bagriantsev ◽  
Elena O. Gracheva
Keyword(s):  
Nervous System ◽  
Environmental Conditions ◽  
Calcium Imaging ◽  
Essential Role ◽  
Physiological Responses ◽  
Quiescent State ◽  
Physiological Changes ◽  
In Vivo Calcium Imaging

ABSTRACT Hibernators thrive under harsh environmental conditions instead of initiating canonical behavioral and physiological responses to promote survival. Although the physiological changes that occur during hibernation have been comprehensively researched, the role of the nervous system in this process remains relatively underexplored. In this Review, we adopt the perspective that the nervous system plays an active, essential role in facilitating and supporting hibernation. Accumulating evidence strongly suggests that the hypothalamus enters a quiescent state in which powerful drives to thermoregulate, eat and drink are suppressed. Similarly, cardiovascular and pulmonary reflexes originating in the brainstem are altered to permit the profoundly slow heart and breathing rates observed during torpor. The mechanisms underlying these changes to the hypothalamus and brainstem are not currently known, but several neuromodulatory systems have been implicated in the induction and maintenance of hibernation. The intersection of these findings with modern neuroscience approaches, such as optogenetics and in vivo calcium imaging, has opened several exciting avenues for hibernation research.

Heat

2020 ◽  
pp. 1687-1689
Author(s):  
Michael A. Stroud
Keyword(s):  
Physical Activity ◽  
Body Temperature ◽  
Supportive Care ◽  
Physiological Responses ◽  
Heat Stroke ◽  
Heat Exposure ◽  
High Humidity ◽  
Heat Exhaustion ◽  
Clinical Presentations ◽  
Cold Core

Rising body temperature triggers behavioural and physiological responses including reduction in physical activity, alterations of clothing, skin vasodilatation, and sweating. Heat-related illness is relatively common, especially with high humidity or prolonged physical activity. Risk can be reduced by acclimatization with repeated heat exposure, but some individuals seem to be particularly susceptible. Clinical presentations of heat-related illness include (1) ‘heat exhaustion’—the commonest manifestation, with symptoms including nausea, weakness, headache, and thirst. Patients appear dehydrated, complain of being hot, and are flushed and sweaty. Treatment requires rest and fluids, given orally or (in severe cases) intravenously. (2) ‘Heat stroke’ victims often complain of headache, may be drowsy or irritable, and may claim to feel cold. Core temperature is usually 38–41°C, but the patient is shivering with dry, vasoconstricted skin. Treatment requires (a) aggressive rapid cooling; (b) close biochemical monitoring; (c) supportive care for organ failure. There is significant mortality.

Biochemical and Galvanic Skin Responses to Music Stimuli by College Students in Biology and Music

1992 ◽  
Vol 74 (3_suppl) ◽  
pp. 1079-1090 ◽  
Author(s):  
Sherman D. VanderArk ◽  
Daniel Ely
Keyword(s):  
Plasma Cortisol ◽  
Physiological Responses ◽  
Music Students ◽  
Music Majors ◽  
Physiological Changes ◽  
Biology Students ◽  
Before And After ◽  
Behavioral Therapies ◽  
Skin Responses ◽  
Galvanic Skin Responses

The purpose of this study was to examine biochemical and physiological responses to musical stimuli. Specifically, university music and biology students' plasma levels of norepinephrine, endorphin, and Cortisol, and their galvanic skin responses were measured before and after listening to two different musical selections in an anechoic chamber and during controlled silence. The results indicated that biochemical variables changed significantly in both groups during listening to music but were not different during the controlled silence. These data suggest that music majors may listen more analytically to music. GSR responses were significantly higher for music majors than biology majors, and plasma Cortisol increased in music students but decreased in biology students. Music which elicits specific emotions induces physiological changes which may be beneficial to relaxation and behavioral therapies.

Electrolyte supplementation of live export cattle to the Middle East

2007 ◽  
Vol 47 (2) ◽  
pp. 119 ◽  
Author(s):  
D. T. Beatty ◽  
A. Barnes ◽  
R. Taplin ◽  
M. McCarthy ◽  
S. K. Maloney
Keyword(s):  
Middle East ◽  
Western Australia ◽  
Bos Taurus ◽  
Stocking Density ◽  
High Heat ◽  
Economic Benefits ◽  
Acid Base Balance ◽  
Night Time ◽  
Urine Ph ◽  
Live Export

Eighty Bos taurus crossbred steers sourced from southern Western Australia were monitored to assess the efficacy of electrolyte supplementation on board a livestock vessel travelling to the Middle East during the northern hemisphere summer. Electrolytes (1.8 g/L NaHCO3 and 3.5 g/L KCl) were added to the drinking water of treatment steers (n = 39) allocated to three pens on the starboard side of the ship. Control steers (n = 40) were allocated to three pens on the port side of the ship. The combined area of the three treatment and three control pens was 61.1 and 63.6 m2 respectively, giving a stocking density of 1.57 and 1.55 m2 per steer, respectively. Steers were loaded in Fremantle, Western Australia and given 3 days to acclimatise to on-board conditions before being weighed (day 1), after which electrolyte supplementation began while the vessel docked at Port Headland, Western Australia. Feed and water were available ad libitum throughout the experiment. Steers were weighed again on day 18, before discharge in the Middle East. During electrolyte supplementation, wet bulb temperature ranged from 21.3 (day 2) to 31.8°C (day 18). Over the last 3 days of the experiment, wet bulb temperature ranged from 29.0 to 31.8°C with no diurnal variation or night-time cooling. No open-mouth panting was recorded in either group and although animals encountered periods of high heat and humidity (as indicated by increased respiratory rates), the steers were not considered clinically heat stressed during the experiment. After 18 days of electrolyte supplementation, treatment steers had a 2.9 ± 1.7% liveweight advantage compared with control steers (P < 0.001). Urine was collected on days 8 and 16 of the experiment and treatment steers maintained a higher urine pH compared with control steers on both days (day 8; 8.6 v. 8.2 and day 16; 8.2 v. 7.9; P < 0.01). Liveweight advantages and improved regulation of acid–base balance may provide welfare and economic benefits to the live export industry.

Adaptation to short-term respiratory effects of ozone in men exposed repeatedly

1977 ◽  
Vol 43 (1) ◽  
pp. 82-85 ◽  
Author(s):  
J. D. Hackney ◽  
W. S. Linn ◽  
J. G. Mohler ◽  
C. R. Collier
Keyword(s):  
Air Pollution ◽  
Physiological Responses ◽  
Controlled Environment ◽  
Acute Effects ◽  
Short Term ◽  
Respiratory Effects ◽  
Ambient Pollution ◽  
Environment Chamber ◽  
Air Pollution Episodes ◽  
Pollution Episodes

To investigate whether adaptation which modifies some acute effects of ozone (O3) exposure can develop in humans, six male volunteers with respiratory hyperreactivity were exposed in a controlled environment chamber to 0.5 ppm O3 2h/day for 4 successive days under conditions stimulating ambient pollution exposures. One subject showed little measurable response, while five showed function decrement on exposure days 1–3 which was largely reversed by day 4. Symptom responses generally paralleled the physiological responses. These results suggest that at least some humans adapt to O3 exposure at concentrations occurring in severe community air pollution episodes, to the extent that obvious acute respiratory effects are prevented. Other adverse effects of O3 may not be prevented by this adaptation.

Physiological Responses of Rainbow Trout (Oncorhynchus mykiss) to Prolonged Exposure to Soft Water

1996 ◽  
Vol 69 (6) ◽  
pp. 1419-1441 ◽  
Author(s):  
S. F. Perry ◽  
S. G. Reid ◽  
E. Wankiewicz ◽  
V. Iyer ◽  
K. M. Gilmour
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Prolonged Exposure ◽  
Physiological Responses ◽  
Soft Water ◽  
Rainbow Trout Oncorhynchus Mykiss

The Effects of Body composition (Percent Fat) On Acclimatization to Heat

1981 ◽  
Vol 25 (1) ◽  
pp. 774-778
Author(s):  
Alex Loewenthal ◽  
David J. Cochran ◽  
Michael W. Riley
Keyword(s):  
Heart Rate ◽  
Weight Loss ◽  
Body Composition ◽  
Skin Temperature ◽  
Heat Exposure ◽  
Temperature Differential ◽  
Mean Skin Temperature ◽  
Physiological Variables ◽  
The Core ◽  
Rate Of Decay

Nine fully acclimatized men falling in the lean, medium and obese categories of body composition were observed during heat exposure periods for four days following acclimatization decay periods of various lengths in order to determine the effects of body composition on the decay and reinduction of acclimatization. The physiological variables taken into consideration were core temperature, “DuBois” mean skin temperature, heart rate, weight loss due to perspiration and the temperature differential between the core and surface. All of the men were subjected to an acclimatization schedule of twelve daily sessions in order to insure that they were all fully acclimatized. Three decay, or non-exposure, periods of four, eight and twelve days were each followed by four days of reinduction. It was determined that body composition does not affect the rate of decay or reinduction of acclimatization, although this parameter as well as the extent of decay and the duration of the reinduction period does affect the physiological variables monitored in this study.

Temperature regulation in the new-born lamb. V. Summit metabolism

1962 ◽  
Vol 13 (1) ◽  
pp. 100 ◽  
Author(s):  
G Alexander
Keyword(s):  
Metabolic Rate ◽  
Heat Loss ◽  
Rectal Temperature ◽  
Prolonged Exposure ◽  
High Heat ◽  
Practical Significance ◽  
Body Temperatures ◽  
Prolonged Fasting ◽  
Body Weights ◽  
Summit Metabolic Rate

"Summit metabolism" was estimated by measuring respiratory exchange during a 20 min period of falling rectal temperature. The rate of fall was controlled at about 1°C per 20 min, by varying the wind velocity while the lamb was exposed to conditions of high heat loss. At body temperatures near normal, summit metabolism was not predictable from rectal temperature. Below 36°C the metabolic rate was proportional to rectal temperature. When expressed as kilocalories per kilogram per hour, summit metabolism in young lambs was approximately constant at all body weights, and hence summit, metabolism per unit of surface area increased with increasing body weight. Heavy lambs are therefore able to maintain homeothermy under conditions of higher heat loss than light lambs. Summit metabolism was usually established at about 17 kcal kg-1 hr-1 within half an hour of birth, i.e. heat production increased rapidly to 15 times foetal levels or five times "basal" levels. There was no increase after ingestion of milk, and the summit metabolic rate appeared to decline slowly with advancing age. It also declined during prolonged exposure to cold and during prolonged fasting, particularly in very young lambs. Blood analyses indicated a great mobilization of fat and carbohydrate during exposure to conditions which evoked a summit response. The practical significance of these results is discussed.

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