Ambient temperature and annual timing affect torpor bouts and euthermic phases of hibernating European ground squirrels (Spermophilus citellus)

2009 ◽  
Vol 87 (3) ◽  
pp. 204-210 ◽  
Author(s):  
István Németh ◽  
Viktor Nyitrai ◽  
Vilmos Altbäcker
Keyword(s):  
Ambient Temperature ◽  
Thermal Conditions ◽  
Ground Squirrels ◽  
Typical Pattern ◽  
Internal Factors ◽  
Ambient Temperatures ◽  
Timing Effect ◽  
Temperature State ◽  
Timing Pattern ◽  
Spermophilus Citellus

The low body temperature state of hibernating mammals is interrupted regularly by short euthermic phases. The frequency of these euthermic phases changes according to the phase of hibernation. This typical pattern, common among ground squirrels (genus Spermophilus F. Cuvier, 1825), can be regulated by internal factors and affected by outside temperature. To evaluate the effects of internal annual timing and ambient temperature, we monitored nest temperatures of overwintering European ground squirrels ( Spermophilus citellus (L., 1766)) under three temperature conditions during late hibernation (9, 5, 0 °C). Our results showed that in spite of constant thermal conditions, an annual timing effect changed torpor-bout length (TBL) at 9 and 5 °C but not at 0 °C. Ambient temperature had an independent influence on TBL and euthermic phases. The loss in body mass was higher at higher ambient temperatures and was affected by TBL and euthermic phases. Thus, the hibernation pattern of European ground squirrels is regulated by both an annual timing pattern and the ambient temperature in the hibernacula.

Parasympathetic influence on heart rate in euthermic and hibernating ground squirrels.

1995 ◽  
Vol 198 (4) ◽  
pp. 931-937 ◽  
Author(s):  
M B Harris ◽  
W K Milsom
Keyword(s):  
Heart Rate ◽  
Ambient Temperature ◽  
Parasympathetic Nervous System ◽  
Ground Squirrels ◽  
Relative Role ◽  
Body Temperatures ◽  
Inotropic Effects ◽  
Ambient Temperatures ◽  
Isolated Hearts ◽  
C 32

The relative role of the parasympathetic nervous system during deep hibernation is enigmatic. Conflicting hypotheses exist, and both sides draw support from investigations of vagal influence on the heart. Recent studies have shown cardiac chronotropic and inotropic effects of parasympathetic stimulation and inhibition in isolated hearts and anesthetized animals at hibernating body temperatures. No studies, however, have demonstrated such occurrences in undisturbed deeply hibernating animals. The present study documents respiratory-related alterations in heart rate during euthermia and hibernation at ambient temperatures of 15, 10 and 5 degrees C mediated by parasympathetic influence. During quiet wakefulness, euthermic squirrels breathed continuously and exhibited a 29% acceleration in heart rate during inspiration. During deep undisturbed hibernation, at 15, 10 and 5 degrees C ambient temperature, animals exhibited an episodic breathing pattern and body temperatures were slightly above ambient temperature. At each temperature, heart rate during the respiratory episode was greater than that during the apnea. The magnitude of this ventilatory tachycardia decreased with ambient temperature, being 108% at 15 degrees C, 32% at 10 degrees C and 11.5% at 5 degrees C. Animals exposed to 3% CO2 at 5 degrees C, which significantly increased ventilation, still exhibited an 11.7% increase in heart rate during breathing. Thus, the magnitude of the ventilation tachycardia was independent of the level of ventilation, at least over the range studied. Inhibition of vagus nerve conduction at 5 degrees C was achieved using localized nerve block. This led to an increase in apneic heart rate and abolished the ventilatory tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Liver heat production and temperature regulation in the anesthetized dog

1979 ◽  
Vol 237 (5) ◽  
pp. R334-R339 ◽  
Author(s):  
P. Baconnier ◽  
G. Benchetrit ◽  
M. Tanche
Keyword(s):  
Ambient Temperature ◽  
Heat Production ◽  
Linear Correlation ◽  
Temperature Regulation ◽  
Thermal Conditions ◽  
Calorimetric Method ◽  
Ambient Temperatures ◽  
Blood Flows ◽  
Physiological Range ◽  
Negative Linear Correlation

Liver heat production (LHP) was measured in the anesthetized dog by a new calorimetric method. Blood flows and temperatures were measured at the same points. The method avoided damage of liver innervation and vascularization. Changes of LHP were investigated under different thermal conditions. Measurements at controlled arterial temperatures within the physiological range showed changes of LHP when arterial temperature was randomly increased or decreased. When measured LHP was compared in experiments carried out at different ambient temperatures, a negative linear correlation was found between LHP and the ambient temperature. It was concluded that liver heat production may be a factor in temperature regulation.

scholarly journals ENDOTHERMY IN THE SOLITARY BEE ANTHOPHORA PLUMIPES: INDEPENDENT MEASURES OF THERMOREGULATORY ABILITY, COSTS OF WARM-UP AND THE ROLE OF BODY SIZE

1993 ◽  
Vol 174 (1) ◽  
pp. 299-320 ◽  
Author(s):  
G. N. Stone
Keyword(s):  
Ambient Temperature ◽  
Heat Loss ◽  
Body Mass ◽  
Thermal Power ◽  
Thermal Conditions ◽  
Energetic Cost ◽  
Solitary Bee ◽  
Warm Up ◽  
Ambient Temperatures ◽  
Thoracic Temperature

1. This study examines variation in thoracic temperatures, rates of pre-flight warm-up and heat loss in the solitary bee Anthophora plumipes (Hymenoptera; Anthophoridae). 2. Thoracic temperatures were measured both during free flight in the field and during tethered flight in the laboratory, over a range of ambient temperatures. These two techniques give independent measures of thermoregulatory ability. In terms of the gradient of thoracic temperature on ambient temperature, thermoregulation by A. plumipes is more effective before flight than during flight. 3. Warm-up rates and body temperatures correlate positively with body mass, while mass-specific rates of heat loss correlate negatively with body mass. Larger bees are significantly more likely to achieve flight temperatures at low ambient temperatures. 4. Simultaneous measurement of thoracic and abdominal temperatures shows that A. plumipes is capable of regulating heat flow between thorax and abdomen. Accelerated thoracic cooling is only demonstrated at high ambient temperatures. 5. Anthophora plumipes is able to fly at low ambient temperatures by tolerating thoracic temperatures as low as 25 sC, reducing the metabolic expense of endothermic activity. 6. Rates of heat generation and loss are used to calculate the thermal power generated by A. plumipes and the total energetic cost of warm-up under different thermal conditions. The power generated increases with thoracic temperature excess and ambient temperature. The total cost of warm-up correlates negatively with ambient temperature.

Broiler trailer thermal conditions during cold climate transport

2012 ◽  
Vol 92 (2) ◽  
pp. 109-122 ◽  
Author(s):  
N. A. Burlinguette ◽  
M. L. Strawford ◽  
J. M. Watts ◽  
H. L. Classen ◽  
P. J. Shand ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Thermal Conditions ◽  
Cold Climate ◽  
Ambient Conditions ◽  
Humidity Ratio ◽  
Ambient Temperatures ◽  
Thermal Environments ◽  
Load Volume ◽  
Heat And Moisture ◽  
Roof Vents

Burlinguette, N. A., Strawford, M. L., Watts, J. M., Classen, H. L., Shand, P. J. and Crowe, T. G. 2012. Broiler trailer thermal conditions during cold climate transport. Can. J. Anim. Sci. 92: 109–122. Thermal environments within broiler transport vehicles are dependent on ambient conditions and, if poorly managed, can be a welfare concern. To effectively manage broiler transport, the environmental conditions throughout vehicles must be understood. Under standard commercial practices, temperature and humidity levels in double-trailer broiler vehicles were examined for a range of ambient temperatures (−24 to 11°C). During warmer ambient conditions (9.8°C) trailer roof vents and side curtains were all open, which resulted in a narrowing of the on-board temperature range (10.3 to 16.7°C). As ambient temperature cooled side curtains and some of the roof vents were closed. This resulted in increasingly variable and more extreme thermal conditions, with heat and moisture accumulated along the midline of the load near the front of the lead trailer and near the back of the rear trailer. At an ambient temperature of −22.1°C trailer temperatures ranged from −20.7 to 21.7°C with an estimated 58.6% of the load volume being exposed to temperatures below 0°C. In addition, the trailer humidity ratio rose 14.0 g kg−1 above ambient and conditions approached saturation (RH>80%) in 55.2% of the load volume. These results support the need to find a means to remove moisture and redistribute heat on broiler trailers during cold ambient conditions.

scholarly journals Postprandial insulin and nutrient concentrations in lipopolysaccharide-challenged growing pigs reared in thermoneutral and high ambient temperatures1

2019 ◽  
Vol 97 (8) ◽  
pp. 3354-3368
Author(s):  
Paulo Henrique Reis Furtado Campos ◽  
Elodie Merlot ◽  
David Renaudeau ◽  
Jean Noblet ◽  
Nathalie Le Floc’h
Keyword(s):  
Ambient Temperature ◽  
Amino Nitrogen ◽  
Thermal Conditions ◽  
Experimental Period ◽  
Repeated Administration ◽  
Growing Pigs ◽  
Nutrient Concentrations ◽  
Ambient Temperatures ◽  
Lps Challenge ◽  
Postprandial Insulin

Abstract The aim of this study was to evaluate the associated effects of ambient temperature and inflammation caused by repeated administration of Escherichia coli lipopolysaccharide (LPS) on insulin, energy, and AA metabolism. Twenty-eight pigs were assigned to one of the two thermal conditions: thermoneutral (24 °C) or high ambient temperature (30 °C). The experimental period lasted 17 d, which was divided into a 7-d period without LPS (days −7 to −1), and a subsequent 10-d LPS period (days 1 to 10) in which pigs were administered 5 repeated injections of LPS at 2-d intervals. Postprandial profiles of plasma insulin and nutrients were evaluated through serial blood samples taken on days −4 (P0), 4 (P1), and 8 (P2). Before the LPS-challenge (P0), postprandial concentrations of glucose, lactate, Gln, Ile, Leu, Phe, Tyr, and Val were greater in pigs kept at 24 °C than at 30 °C (P < 0.05). In contrast, Arg, Asp, Gly, His, and Met postprandial concentrations at P0 were lower at 24 °C than at 30 °C (P < 0.05). At both 24 and 30 °C conditions, pigs had greater postprandial concentrations of insulin (P < 0.01) and lower concentrations of NEFA (P < 0.01) and α-amino nitrogen (P < 0.05) at P1 and P2 than at P0. Compared with P0, postprandial concentrations of glucose were greater (P < 0.05) at P1 in pigs kept at 24 °C, and at P1 and P2 in pigs kept at 30 °C. At both ambient temperatures, pigs had lower (P < 0.05) postprandial concentrations of Ala, Gly, His, Ile, Leu, Pro, Ser, Thr, Trp, and Val at P1 and P2 than at P0. Arginine postprandial concentration at P1 was lower than at P0 in pigs kept at 24 °C (P < 0.05), whereas no difference was observed in pigs at 30 °C. Relative to P0, Gln and Tyr concentrations were lower at P1 and P2 in pigs kept at 24 °C (P < 0.01), whereas lower Gln concentration was observed only at P2 (P < 0.01) and lower Tyr only at P1 (P < 0.01) in pigs kept at 30 °C. Our study shows a hyperglycemic and hyperinsulinemic state in LPS-challenged pigs and a greater magnitude of this response in pigs kept at 30 °C. Furthermore, LPS caused important changes in BCAA, His, Thr, and Trp profiles, suggesting the role these AA in supporting the inflammatory response. Finally, our results suggest that LPS-induced effects on postprandial profiles of specific AA (Arg, Gln, Phe, and Tyr) may be modulated by ambient temperature.

scholarly journals Influence of Ambient Temperature on Radiative and Convective Heat Dissipation Ratio in Polymer Heat Sinks

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2286
Author(s):  
Jan Kominek ◽  
Martin Zachar ◽  
Michal Guzej ◽  
Erik Bartuli ◽  
Petr Kotrbacek
Keyword(s):  
Heat Transfer ◽  
Ambient Temperature ◽  
Convective Heat ◽  
Heat Dissipation ◽  
High Surface ◽  
Heat Sinks ◽  
Fourth Power ◽  
Molding Process ◽  
Ambient Temperatures ◽  
University Of Technology

Miniaturization of electronic devices leads to new heat dissipation challenges and traditional cooling methods need to be replaced by new better ones. Polymer heat sinks may, thanks to their unique properties, replace standardly used heat sink materials in certain applications, especially in applications with high ambient temperature. Polymers natively dispose of high surface emissivity in comparison with glossy metals. This high emissivity allows a larger amount of heat to be dissipated to the ambient with the fourth power of its absolute surface temperature. This paper shows the change in radiative and convective heat transfer from polymer heat sinks used in different ambient temperatures. Furthermore, the observed polymer heat sinks have differently oriented graphite filler caused by their molding process differences, therefore their thermal conductivity anisotropies and overall cooling efficiencies also differ. Furthermore, it is also shown that a high radiative heat transfer leads to minimizing these cooling efficiency differences between these polymer heat sinks of the same geometry. The measurements were conducted at HEATLAB, Brno University of Technology.

scholarly journals Insufficient Stability of Clavulanic Acid in Widely Used Child-Appropriate Formulations

Antibiotics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 225
Author(s):  
Ines Mack ◽  
Mike Sharland ◽  
Janneke M. Brussee ◽  
Sophia Rehm ◽  
Katharina Rentsch ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Clavulanic Acid ◽  
Storage Conditions ◽  
Essential Medicines ◽  
Active Components ◽  
Middle Income ◽  
Ambient Temperatures ◽  
Essential Medicines List ◽  
Dispersible Tablets ◽  
The Stability

Amoxicillin-clavulanic acid (AMC) belongs to the WHO Essential Medicines List for children, but for optimal antimicrobial effectiveness, reconstituted dry powder suspensions need to be stored in a refrigerated environment. Many patients in low- and middle-income countries who are sold AMC suspensions would be expected not to keep to the specified storage conditions. We aimed to assess the stability of both ingredients in liquid formulations and dispersible tablets, combined with nationally representative data on access to appropriate storage. Degradation of amoxicillin (AMX) and clavulanic-acid (CLA) was measured in suspensions and dispersible tablets commercially available in Switzerland at different ambient temperatures (8 °C vs. 28 °C over 7 days, and 23 °C vs. 28 °C over 24 h, respectively). Data on access to refrigeration and electricity were assessed from the USAID-funded Demographic and Health Survey program. In suspensions, CLA degraded to a maximum of 12.9% (95% CI −55.7%, +29.9%) at 8°C and 72.3% (95% CI −82.8%, −61.8%) at a 28 °C ambient temperature during an observation period of 7 days. Dispersible tablets were observed during 24 h and CLA degraded to 15.4% (95% CI −51.9%, +21.2%) at 23 °C and 21.7% (−28.2%, −15.1%) at a 28 °C ambient temperature. There is relevant degradation of CLA in suspensions during a 7-day course. To overcome the stability challenges for all active components, durable child-appropriate formulations are needed. Until then, prescribers of AMC suspensions or pharmacists who sell the drug need to create awareness for the importance of proper storage conditions regarding effectiveness of both antibiotics and this recommendation should be reflected in the WHO Essential Medicines List for children.

Ambient temperature effects on physiological traits of white-tailed deer

1975 ◽  
Vol 53 (6) ◽  
pp. 679-685 ◽  
Author(s):  
J. B. Holter ◽  
W. E. Urban Jr. ◽  
H. H. Hayes ◽  
H. Silver ◽  
H. R. Skutt
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Energy Expenditure ◽  
Ambient Temperature ◽  
Temperature Effects ◽  
Temperature Changes ◽  
Wind Chill ◽  
Ambient Temperatures ◽  
Energy Equilibrium ◽  
Body Energy

Six adult white-tailed deer (Odocoileus virginianus borealis) were exposed to 165 periods of 12 consecutive hours of controlled constant ambient temperature in an indirect respiration calorimeter. Temperatures among periods varied from 38 to 0 (summer) or to −20C (fall, winter, spring). Traits measured were energy expenditure (metabolic rate), proportion of time spent standing, heart rate, and body temperature, the latter two using telemetry. The deer used body posture extensively as a means of maintaining body energy equilibrium. Energy expenditure was increased at low ambient temperature to combat cold and to maintain relatively constant body temperature. Changes in heart rate paralleled changes in energy expenditure. In a limited number of comparisons, slight wind chill was combatted through behavioral means with no effect on energy expenditure. The reaction of deer to varying ambient temperatures was not the same in all seasons of the year.

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