scholarly journals Melanism as a potential thermal benefit in eastern fox squirrels (Sciurus niger)

2019 ◽  
Vol 5 (2) ◽  
pp. 79-87
Author(s):  
Amanda K. Ciurej ◽  
Ashley Oblander ◽  
Andrew W. Swift ◽  
James A. Wilson
Keyword(s):  
Body Condition ◽  
Metabolic Response ◽  
Selective Advantage ◽  
Sciurus Niger ◽  
Response Curves ◽  
Ambient Temperatures ◽  
Surface Temperatures ◽  
Fox Squirrel ◽  
Fox Squirrels ◽  
Skin Temperatures

Abstract Melanistic fox squirrels (Sciurus niger) have expanded westward and increased in frequency in the Omaha, Nebraska, and Council Bluffs, Iowa, metropolitan areas. The selective advantage of melanism is currently unknown, but thermal advantages have been hypothesized, especially in winter. No difference in metabolic response curves were measured between melanistic (black) and rufus (orange) fox squirrels. When exposed to sunny skies, both melanistic and rufus squirrels had higher surface (skin and fur) temperature as ambient temperatures increased. Melanistic squirrel surface temperatures did not differ when squirrels were exposed to sunny or cloudy skies. However, rufus individuals showed significantly lower increases in surface temperatures when under cloudy skies. During fall months, rufus individuals were about 1.5 times more active throughout the day than melanistic individuals. However, in winter, melanistic fox squirrels were approximately 30% more active in the mornings (before 13:00) compared to rufus squirrels. Pre-winter body condition was higher in melanistic (25.5 ± 1.8 g/cm) compared to rufus (20.30 ± 3.6 g/cm) fox squirrels; however, there were no significant differences between melanistic (22.8 ± 1.4 g/cm) and rufus (23.9 ± 0.8 g/cm) fox squirrel post-winter body condition. The results of this study indicate that melanistic fox squirrels may have a slight winter thermal advantage over rufus fox squirrels by maintaining higher skin temperatures.

scholarly journals Eastern fox squirrel (Sciurus niger, Linnaeus 1758) introduction to the Sonoran Desert

Mammalia ◽  
2017 ◽  
Vol 81 (2) ◽  
Author(s):  
Matthew J. Brady ◽  
John L. Koprowski ◽  
R. Nathan Gwinn ◽  
Yeong-Seok Jo ◽  
Kevin Young
Keyword(s):  
United States ◽  
Sonoran Desert ◽  
Sciurus Niger ◽  
Midwestern United States ◽  
The People ◽  
Fox Squirrel ◽  
Fox Squirrels ◽  
The 1960S ◽  
The City

AbstractThe eastern fox squirrel, native to the eastern and midwestern United States, was recently documented in the Sonoran Desert in the vicinity of Yuma, Arizona, constituting the first state record for this species. We surveyed the people of Yuma to determine when and how the squirrels arrived. The squirrels were first observed in the 1960s, but may have been resident for a longer period. Since the 1960s, squirrels have spread throughout the city limits and extended south ~15 km into Somerton, Arizona. How the squirrels arrived is not clear, but must be the result of an introduction, as no nearby populations exist. The persistence of eastern fox squirrels in this unique habitat is due to synanthropic relationships.

Using Thermoelectric Cooling With Tourniquets for Nerve Preservation

2016 ◽  
Author(s):  
M. Trupiano ◽  
S. Aarabi ◽  
A. F. Emery
Keyword(s):  
Thermal Conditions ◽  
Ambient Conditions ◽  
Transfer Coefficients ◽  
Thermoelectric Coolers ◽  
Ambient Temperatures ◽  
Nerve Preservation ◽  
Heat Transfer Coefficients ◽  
Surface Temperatures ◽  
Element Simulation ◽  
Free And Forced Convection

The use of a tourniquet leads to nerve damage, even if applied for short periods of time. This damage can be minimized if the limb is cooled. Because of the low conductivities of human tissue, core limb cooling is slow unless the surface temperature is very cool. Subzero surface temperatures can lead to skin injury (i.e., frostbite). Ideally one would adjust the limb surface temperatures as a function of time to maximize the cooling rate while avoiding permanent tissue damage. One possible approach is to use a thermoelectric cooler (TEC) in conjunction with a programmable power supply. TEC performance varies strongly with heat absorption rate, a function of limb thermal properties, and hot side temperatures that are strongly affected by the surface conditions on the hot side, i.e., overall heat transfer coefficients and ambient conditions. The paper describes the use of finite element simulation to predict the usefulness of using thermoelectric coolers applied to the surface of a limb when compared to the standard approach of using ice packs. Since the TEC performance is strongly influenced by its warm side thermal conditions, experimental results are presented for different ambient temperatures, free and forced convection, and evaporation of water from a wickable covering.

A STUDY OF THE EFFECT OF COLD ON JOINT TEMPERATURE AND MOBILITY

1951 ◽  
Vol 29 (5) ◽  
pp. 255-262 ◽  
Author(s):  
John Hunter ◽  
M. G. Whillans
Keyword(s):  
Knee Joint ◽  
Test Object ◽  
Joint Stiffness ◽  
Ambient Temperatures ◽  
Significant Fall ◽  
Average Skin ◽  
Skin Temperatures ◽  
Rectal Muscle

Exposure to zero and subzero ambient temperatures results in a significant fall in joint temperature, where the knee joint of the cat was used as test object. The fall in rectal, muscle, and “average” skin temperatures for similar exposures is considerably less. Low joint temperature is associated with increased joint stiffness.

Dual core and shell temperature regulation during sea acclimatization in Gentoo penguins (Pygoscelis papua)

1994 ◽  
Vol 266 (4) ◽  
pp. R1319-R1326 ◽  
Author(s):  
E. Dumonteil ◽  
H. Barre ◽  
J. L. Rouanet ◽  
M. Diarra ◽  
J. Bouvier
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Thermal Insulation ◽  
Cold Water ◽  
Threshold Temperature ◽  
Ambient Temperatures ◽  
Adaptation To Cold ◽  
Marine Life ◽  
Shell Temperature ◽  
Skin Temperatures

Penguins are able to maintain a high and constant body temperature despite a thermally constraining environment. Evidence for progressive adaptation to cold and marine life was sought by comparing body and peripheral skin temperatures, metabolic rate, and thermal insulation in juvenile and adult Gentoo penguins exposed to various ambient temperatures in air (from -30 to +30 degrees C) and water (3-35 degrees C). Juvenile penguins in air showed metabolic and insulative capacities comparable with those displayed by adults. Both had a lower critical temperature (LCT) close to 0 degree C. In both adults and juveniles, the intercept of the metabolic curve with the abscissa at zero metabolic rate was far below body temperature. This was accompanied by a decrease in thermal insulation below LCT, allowing the preservation of a threshold temperature in the shell. However, this shell temperature maintenance was progressively abandoned in immersed penguins as adaptation to marine life developed, probably because of its prohibitive energy cost in water. Thus adaptation to cold air and to cold water does not rely on the same kind of reactions. Both of these strategies fail to follow the classical sequence linking metabolic and insulative reactions in the cold.

Thermoregulatory responses of febrile sheep to spinal and hypothalamic heating

1987 ◽  
Vol 253 (6) ◽  
pp. R868-R876 ◽  
Author(s):  
C. M. Blatteis ◽  
R. Necker ◽  
J. R. Hales ◽  
A. A. Fawcett ◽  
K. Hirata
Keyword(s):  
Blood Flow ◽  
Skin Blood Flow ◽  
O2 Consumption ◽  
Plateau Phase ◽  
Lower Range ◽  
Ambient Temperatures ◽  
Hypothalamic Thermosensitivity ◽  
The Mean ◽  
Conscious Sheep ◽  
Skin Temperatures

Fever was induced by the intravenous injection of 0.25 microgram/kg of lipopolysaccharide (LPS) from Escherichia coli in eight conscious sheep exposed to ambient temperatures adjusted to the lower range of thermoneutrality. Chronic spinal or hypothalamic thermodes were perfused with water of 44 degrees C for 20 min or for most of the rising phase of fever (100 min of the mean 166 min total rise time). The effects of spinal and hypothalamic heating were identical. Thus, before LPS, spinal or hypothalamic heating did not affect the rate of O2 consumption (VO2) but increased skin blood flow (as indicated by skin temperatures) and elicited panting; therefore rectal temperature (Tre) fell. During fever rise, the already reduced skin blood flow and respiratory rate were not affected by spinal or hypothalamic heating, but the increased VO2 was reduced; consequently, the rise in Tre was attenuated. During the plateau phase of fever, all responses were similar to those seen before LPS. In febrilysis, heating strongly enhanced the operating heat loss mechanisms and, hence, augmented the fall in Tre. Thus, although the thermoeffectors activated by spinal or hypothalamic heating were modified during the different stages of fever, the effect on body temperature was nearly the same. Therefore there seems to be no change in spinal or hypothalamic thermosensitivity during fever in sheep.

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