scholarly journals Physiological responses of Houbara bustards to high ambient temperatures

2002 ◽  
Vol 205 (4) ◽  
pp. 503-511 ◽  
Author(s):  
B. Irene Tieleman ◽  
Joseph B. Williams ◽  
Frédéric LaCroix ◽  
Patrick Paillat
Keyword(s):  
Heat Transfer ◽  
Body Composition ◽  
Physiological Responses ◽  
Resting Metabolic Rate ◽  
High Ambient Temperature ◽  
Physiological Mechanisms ◽  
Evaporative Water ◽  
Heat Gain ◽  
Ambient Temperatures ◽  
Dry Heat

SUMMARYDesert birds often experience a scarcity of drinking water and food and must survive episodes of high ambient temperature (Ta). The physiological mechanisms that promote survival during extended periods of high Ta have received little attention. We investigated the physiological responses of wild-caught and captive-reared Houbara bustards, Chlamydotis macqueenii, to Ta values ranging from below 0°C to 55°C, well above those in most previous studies of birds. Captive-reared Houbara bustards (mass 1245±242 g, N=7, mean ± s.d.) in summer have a resting metabolic rate (RMR) of 261.4 kJ day–1, 26 % below allometric predictions, and a total evaporative water loss (TEWL) at 25°C of 25.8 g day–1, 31 % below predictions. When Ta exceeded body temperature (Tb), the dry heat transfer coefficient decreased, a finding supporting the prediction that birds should minimize dry heat gain from the environment at high Ta values. Houbara bustards withstand high Ta values without becoming hyperthermic; at 45°C, Tb was on average 0.9°C higher than at 25°C. RMR and TEWL of captive-bred Houbara bustards were 23 % and 46 % higher in winter than in summer, respectively. Captive-reared Houbara bustards had a 17 % lower RMR and a 28 % lower TEWL than wild-born birds with similar genetic backgrounds. Differences in body composition between wild-caught and captive-reared birds were correlated with differences in physiological performance.

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 Correction to: The effect of moderate intermittent versus continuous energy restriction on body composition and resting metabolic rate in resistance-trained females: A randomized controlled trial

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Madelin R. Siedler ◽  
Eric T. Trexler ◽  
Megan N. Humphries ◽  
Priscila Lamadrid ◽  
Brian Waddell ◽  
...  
Keyword(s):  
Randomized Controlled Trial ◽  
Body Composition ◽  
Metabolic Rate ◽  
Controlled Trial ◽  
Resting Metabolic Rate ◽  
Energy Restriction ◽  
Randomized Controlled ◽  
Continuous Energy

An amendment to this paper has been published and can be accessed via the original article.

scholarly journals Heat transfer, physiological responses, and subjective perceptions during short contact time with wood or other materials

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Yuko Tsunetsugu ◽  
Masaki Sugiyama
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Blood Pressure ◽  
Physiological Stress ◽  
Physiological Responses ◽  
Chamaecyparis Obtusa ◽  
Material Interface ◽  
Japanese Cypress ◽  
Subjective Perceptions ◽  
Short Contact Time

AbstractThis study investigates the physiological responses and subjective perceptions of touching wood. In particular, it focuses on their respective relationships with the amount of heat transfer across the hand–material interface during contact. The study participants included 55 university students (20 females and 35 males) who gave written informed consent. The participants’ blood pressure, pulse rate, and cerebral blood hemoglobin concentrations were measured continuously for 90 s while they gently held vertical bar-shaped specimens of Japanese cypress (Chamaecyparis obtusa), Japanese oak (Quercus crispula), polyethylene, and aluminum. The specimens also included wood with a surface coating. We measured subjective warmth and comfort as well as the heat flux between the palm and the surface of the material. The wooden materials were rated as significantly warmer compared to aluminum and polyethylene, regardless of the wood species (cypress or oak) or its coating; this result corresponds with smaller heat transfers in the wooden materials. Additionally, the wooden materials were more comfortable to hold as compared to the aluminum bar. Based on the changes in blood pressure, touching Japanese cypress and uncoated Japanese oak were interpreted to induce less physiological stress. Therefore, we can conclude that wood, with lower thermal conductivity, feels warm, and it causes relatively smaller physiological changes compared to other materials with higher thermal conductivity. Thus, they may present less physiological burdens when touched.

Inhibiting ventilatory evaporation produces an adaptive increase in cutaneous evaporation in mourning doves Zenaida macroura

1999 ◽  
Vol 202 (21) ◽  
pp. 3021-3028 ◽  
Author(s):  
T.C. Hoffman ◽  
G.E. Walsberg
Keyword(s):  
Skin Surface ◽  
The Body ◽  
Evaporative Heat Loss ◽  
Evaporative Water ◽  
Zenaida Macroura ◽  
Ambient Temperatures ◽  
Rapid Adjustment ◽  
Mourning Doves ◽  
A Minor ◽  
Cutaneous Evaporation

We tested the hypothesis that birds can rapidly change the conductance of water vapor at the skin surface in response to a changing need for evaporative heat loss. Mourning doves (Zenaida macroura) were placed in a two-compartment chamber separating the head from the rest of the body. The rate of cutaneous evaporation was measured in response to dry ventilatory inflow at three ambient temperatures and in response to vapor-saturated ventilatory inflow at two ambient temperatures. At 35 degrees C, cutaneous evaporation increased by 72 % when evaporative water loss from the mouth was prevented, but no increase was observed at 45 degrees C. For both dry and vapor-saturated treatments, cutaneous evaporation increased significantly with increased ambient temperature. Changes in skin temperature made only a minor contribution to any observed increase in cutaneous evaporation. This indicates that Z. macroura can effect rapid adjustment of evaporative conductance at the skin in response to acute change in thermoregulatory demand.

scholarly journals Influence of body composition on physical activity validation studies using doubly labeled water

2004 ◽  
Vol 96 (4) ◽  
pp. 1357-1364 ◽  
Author(s):  
Louise C. Mâsse ◽  
Janet E. Fulton ◽  
Kathleen L. Watson ◽  
Matthew T. Mahar ◽  
Michael C. Meyers ◽  
...  
Keyword(s):  
Physical Activity ◽  
Body Composition ◽  
Energy Expenditure ◽  
Body Mass ◽  
Resting Metabolic Rate ◽  
Fat Free Mass ◽  
Doubly Labeled Water ◽  
Comparison Analysis ◽  
Methods Comparison ◽  
Statistical Procedures

This study investigated the influence of two approaches (mathematical transformation and statistical procedures), used to account for body composition [body mass or fat-free mass (FFM)], on associations between two measures of physical activity and energy expenditure determined by doubly labeled water (DLW). Complete data for these analyses were available for 136 African American (44.1%) and Hispanic (55.9%) women (mean age 50 ± 7.3 yr). Total energy expenditure (TEE) by DLW was measured over 14 days. Physical activity energy expenditure (PAEE) was computed as 0.90 × TEE - resting metabolic rate. During week 2, participants wore an accelerometer for 7 consecutive days and completed a 7-day diary. Pearson's product-moment correlations and three statistical procedures (multiple regressions, partial correlations, and allometric scaling) were used to assess the effect of body composition on associations. The methods-comparison analysis was used to study the effect of body composition on agreement. The statistical procedures demonstrated that associations improved when body composition was included in the model. The accelerometer explained a small but meaningful portion of the variance in TEE and PAEE after body mass was accounted for. The methods-comparison analysis confirmed that agreement with DLW was affected by the transformation. Agreement between the diary (transformed with body mass) and TEE reflected the association that exists between body mass and TEE. These results suggest that the accelerometer and diary accounted for a small portion of TEE and PAEE. Most of the variance in DLW-measured energy expenditure was explained by body mass or FFM.

scholarly journals Body composition and resting metabolic rate in obese adolescents

2015 ◽  
Vol 48 (4) ◽  
pp. 359 ◽  
Author(s):  
Bruno A. P. de Oliveira ◽  
Camila B. Gardim ◽  
Carolina N. Ferreira ◽  
Suziane U. Cayres ◽  
Ismael F. Freitas Junior
Keyword(s):  
Body Composition ◽  
Metabolic Rate ◽  
Resting Metabolic Rate ◽  
Obese Adolescents

Objetivo: Analisar a composição corporal e taxa metabólica de repouso (TMR) de adolescentes com obesidade. Metodologia: Foram avaliados 58 adolescentes, entre 12 e 16 anos (13,7±1,2 anos), com obesidade. A composição corporal foi mensurada por meio da Absortiometria de Raios-x de Dupla Energia (DEXA). A taxa metabólica de repouso e a oxidação de glicose e lipídeos foram determinadas pela medida do oxigênio consumido e pela produção de dióxido de carbono. Foi utilizado teste t de Student para variáveis independentes, análise de regressão linear múltipla e correlação de Pearson, com significância de p<5%. Resultados: Foram observadas diferenças na porcentagem de gordura corporal (p=0,01), porcentagem de massa corporal magra (MCM) (p=0,01), porcentagem de gordura do tronco (p=0,01), massa magra membro inferior (p=0,01) e taxa metabólica de repouso (p=0,04) entre os sexos masculino e feminino. No sexo masculino a MCM foi a melhor preditora de TMR (p=0,01). Houve correlação positiva entre TMR e MCM, assim como observada associação entre a oxidação lipídica e MCM. Conclusão: A composição corporal total e por segmento corporal influenciam a taxa metabólica de repouso e a oxida- ção de substratos. Além disso, a MCM pode ser considerada um fator de aumento do gasto energético de repouso de adolescentes com obesidade.

scholarly journals The ship of the desert. The dromedary camel (Camelus dromedarius), a domesticated animal species well adapted to extreme conditions of aridness and heat

Rangifer ◽  
1990 ◽  
Vol 10 (3) ◽  
pp. 231 ◽  
Author(s):  
S. Bornstein
Keyword(s):  
Animal Species ◽  
Physiological Adaptation ◽  
Dromedary Camel ◽  
Large Animal ◽  
Water Losses ◽  
Evaporative Water ◽  
Ambient Temperatures ◽  
Adaptive Mechanisms ◽  
Adaptation To Heat ◽  
Arabian Camel

The dromedary camel (Camel dromedarius) is extremely well adapted to life in hot and arid lands. In terms of physiological adaptation to heat and water deprivation it surpasses by far every other large animal of which data have been collected. None of the adaptive mechanisms to cope with the environmental stresses are unique to the Arabian camel, but the efficiency of its adaptation is superior. At high ambient temperatures the camels adapt to the scarcity of water by reducing their faecal, urinary and evaporative water losses. During dehydration, the kidneys reduce water losses both by decreasing the glomerual filtration rate and by increasing the tubular reabsorption of water. Also their ability of regulating their body temperature from 34.5-40.7 °C conserves a lot of water, when most needed.

Effect of age on body composition and resting metabolic rate

1990 ◽  
Vol 259 (2) ◽  
pp. E233-E238 ◽  
Author(s):  
N. K. Fukagawa ◽  
L. G. Bandini ◽  
J. B. Young
Keyword(s):  
Body Composition ◽  
Metabolic Rate ◽  
Isotope Dilution ◽  
Resting Metabolic Rate ◽  
Bioelectrical Impedance ◽  
Impedance Analysis ◽  
Open Circuit ◽  
Fat Free Mass ◽  
The Difference ◽  
Old Men

The relationship between fat-free mass (FFM) and resting metabolic rate (RMR) was compared in young men (n = 24; age 18-33 yr), old men (n = 24; 69-89 yr), and old women (n = 20; 67-75 yr). Body composition was assessed using anthropometry, bioelectrical impedance analysis (BIA), and isotope dilution with 18O-labeled water. RMR was measured at least twice using an open-circuit indirect calorimetry system with a ventilated hood. The results indicate that the different methods for assessing body composition vary substantially and should not be used interchangeably. Anthropometry was not adequate to assess group differences in body fatness, although skinfold measures may be appropriate for within-group comparisons. BIA correlated well with the isotope-dilution technique and may be a useful measure of FFM. Finally, RMR was lower in the old men than the young (1.04 +/- 0.02 vs. 1.24 +/- 0.03 kcal/min, P less than 0.001) and remained lower even when adjusted for FFM estimated by isotope dilution (P less than 0.001). RMR in the women was also lower (0.84 +/- 0.02 kcal/min), but in contrast to the difference between young and old men, RMR adjusted for FFM did not differ (P = 0.16) between old men and women. Therefore, it is clear that differences in FFM cannot fully account for the lower RMR in the old, suggesting that aging is associated with an alteration in tissue energy metabolism.

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