scholarly journals Exoskeleton may influence the internal body temperatures of Neotropical dung beetles (Col. Scarabaeinae)

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3349 ◽  
Author(s):  
Valentina Amore ◽  
Malva I.M. Hernández ◽  
Luis M. Carrascal ◽  
Jorge M. Lobo

The insect exoskeleton is a multifunctional coat with a continuum of mechanical and structural properties constituting the barrier between electromagnetic waves and the internal body parts. This paper examines the ability of beetle exoskeleton to regulate internal body temperature considering its thermal permeability or isolation to simulated solar irradiance and infrared radiation. Seven Neotropical species of dung beetles (Coleoptera, Scarabaeinae) differing in colour, surface sculptures, size, sexual dimorphism, period of activity, guild category and altitudinal distribution were studied. Specimens were repeatedly subjected to heating trials under simulated solar irradiance and infrared radiation using a halogen neodymium bulb light with a balanced daylight spectrum and a ceramic infrared heat emitter. The volume of exoskeleton and its weight per volume unit were significantly more important for the heating rate at the beginning of the heating process than for the asymptotic maximum temperature reached at the end of the trials: larger beetles with relatively thicker exoskeletons heated more slowly. The source of radiation greatly influences the asymptotic temperature reached, but has a negligible effect in determining the rate of heat gain by beetles: they reached higher temperatures under artificial sunlight than under infrared radiation. Interspecific differences were negligible in the heating rate but had a large magnitude effect on the asymptotic temperature, only detectable under simulated sun irradiance. The fact that sun irradiance is differentially absorbed dorsally and transformed into heat among species opens the possibility that differences in dorsal exoskeleton would facilitate the heat gain under restrictive environmental temperatures below the preferred ones. The findings provided by this study support the important role played by the exoskeleton in the heating process of beetles, a cuticle able to act passively in the thermal control of body temperature without implying energetic costs and metabolic changes.

2020 ◽  
Vol 39 (1) ◽  
pp. 54-62
Author(s):  
Hua Chen ◽  
Junjiang Chen ◽  
Weijun Wang ◽  
Huan Lin

AbstractThe multimode resonant cavity is the most common cavity. The material often shows on selective heating performance during the heating process due to the effect of microwave heating having a closely relationship with the electromagnetism parameters. This paper is based on finite difference time domain method (FDTD) to establish the electromagnetic-thermal model. The electromagnetic sensitivity property parameters of sodium chloride including relative dielectric constant, loss angle tangent and water content of sodium chloride is studied during the heating and drying process. The heating rate and the electric field distribution of sodium chloride, at the different water content, were simulated with the electromagnetic characteristic parameters changing. The results show that with the electromagnetic sensitivity property parameters varying, the electric field strength, heating rate and steady-state temperature of the heating material will all have a variety in the cavity. Some measures are proposed to improve the heating efficiency and ensure the stability of the microwave heating system in the industrial application.


2018 ◽  
Vol 42 (2) ◽  
pp. 328-337 ◽  
Author(s):  
Andrew M. Herberg ◽  
Véronique St-Louis ◽  
Michelle Carstensen ◽  
John Fieberg ◽  
Daniel P. Thompson ◽  
...  

1956 ◽  
Vol 188 (1) ◽  
pp. 103-112 ◽  
Author(s):  
Knut Schmidt-Nielsen ◽  
Bodil Schmidt-Nielsen ◽  
S. A. Jarnum ◽  
T. R. Houpt

The rectal temperature of normal healthy camels at rest may vary from about 34°C to more than 40°C. Diurnal variations in the winter are usually in the order of 2°C. In summer the diurnal variations in the camel deprived of drinking water may exceed 6°C, but in animals with free access to water the variations are similar to those found in the winter. The variations in temperature are of great significance in water conservation in two ways. a) The increase in body temperature means that heat is stored in the body instead of being dissipated by evaporation of water. At night the excess heat can be given off without expenditure of water. b) The high body temperature means that heat gain from the hot environment is reduced because the temperature gradient is reduced. The effect of the increased body temperature on heat gain from the environment has been calculated from data on water expenditure. These calculations show that under the given conditions the variations in body temperature effect a considerable economy of water expenditure. The evaporative heat regulation in the camel seems to rest exclusively on evaporation from the skin surface (sweating), and there is no apparent increase in respiratory rate or panting connected with heat regulation. The evaporation from isolated skin areas increases linearly with increased heat load. The critical temperature at which the increase sets in is around 35°C. The fur of the camel is an efficient barrier against heat gain from the environment. Water expenditure is increased in camels that have been shorn.


Author(s):  
N. D. Ganyushina ◽  
◽  
A. V. Korosov ◽  
N. A. Litvinov ◽  
N. A. Chetanov ◽  
...  

PEDIATRICS ◽  
1951 ◽  
Vol 7 (2) ◽  
pp. 207-209
Author(s):  
P. VOGEL ◽  
R. E. ROSENFIELD ◽  
M. STEINBERG

THE maintenance of proper body temperature has been a serious problem in the performance of exchange transfusions on newborn infants suffering from hemolytic disease. Many of these infants are in such poor condition that extreme care in their handling is required, including incubation, oxygen and tracheal aspiration. The many procedures necessary create the hazard of prolonged exposure to room temperature, and a number of deaths may have resulted directly or indirectly from hypothermia. In the Children's Hospital in Boston, the entire exchange transfusion is carried out with the infant lying in a Hess bed; this is an ideal situation which undoubtedly is not readily available in most institutions where an exchange transfusion must be performed. The maintenance of body temperature with electric heating pads and/or hot water bottles has proved cumbersome and unsatisfactory, and has resulted in a number of burns, particularly about the buttocks. A washable electric blanket bunting has been designed (see Figs. and 2) to maintain the temperature of newborn infants throughout the procedure of an exchange transfusion, as well as for a period following the procedure, if a heated crib is not available. This bunting was constructed by the General Electric Company using water-proof washable material and employing the principles of the commercial electric blanket. The bunting can be regulated to any desired temperature although the maximum temperature obtainable is 42°C., which avoids the possibility of skin burns. The design of the bunting is simple: it is a bag with a zipper along one side to allow for easy insertion and removal of the baby, and a "U" shaped zippered flap which can be opened to provide a window at the approximate position of the umbilical cord.


2021 ◽  
Vol 315 ◽  
pp. 3-9
Author(s):  
Yuan Gao ◽  
Li Hua Zhan ◽  
Hai Long Liao ◽  
Xue Ying Chen ◽  
Ming Hui Huang

The uniformity of temperature field distribution in creep aging process is very important to the forming accuracy of components. In this paper, the temperature field distribution of 2219 aluminum alloy tank cover during aging forming is simulated by using the finite element software FLUENT, and a two-stage heating process is proposed to reduce the temperature field distribution heterogeneity. The results show that the temperature difference of the tank cover is large in the single-stage heating process, and the maximum temperature difference is above 27°C,which seriously affects the forming accuracy of the tank cover. With two-stage heating process, the temperature difference in the first stage has almost no direct impact on the forming accuracy of the top cover. In the second stage, the temperature difference of the tank cover is controlled within 10°C, compared with the single-stage heating, the maximum temperature difference is reduced by more than 17°C. The two-stage heating effectively reduces the heterogeneity of the temperature field of the top cover. The research provides technical support for the precise thermal mechanical coupling of large-scale creep aging forming components.


Author(s):  
Lu-Yi Wang ◽  
Amanda M. Franklin ◽  
Jay R. Black ◽  
Devi Stuart-Fox

Adaptations to control heat transfer through the integument are a key component of temperature regulation in animals. However, there remain significant gaps in our understanding of how different optical and morphological properties of the integument affect heating rates. To address these gaps, we examined the effect of reflectivity in both ultraviolet-visible and near-infrared wavelengths, surface micro-sculpturing, effective area (area subjected to illumination) and cuticle thickness on radiative heat gain in jewel beetles (Buprestidae). We measured heating rate using a solar simulator to mimic natural sunlight, a thermal chamber to control the effects of conduction and convection, and optical filters to isolate different wavelengths. We found that effective area and reflectivity predicted heating rate. The thermal effect of reflectivity was driven by variation in near-infrared rather than ultraviolet-visible reflectivity. By contrast, cuticle thickness and surface rugosity had no detectable effect. Our results provide empirical evidence that near-infrared reflectivity has an important effect on radiative heat gain. Modulating reflectance of near-infrared wavelengths of light may be a more widespread adaptation to control heat gain than previously appreciated.


Author(s):  
Richard T. Meyer ◽  
Bin Yao

Previous research has assumed that a perfect Proton Exchange Membrane Fuel Cell (PEMFC) body temperature manager is available. Maintaining this temperature at a desired value can ensure a high reaction efficiency over all operation. However, fuel cell internal body temperature control has not been specifically presented so far. This work presents such control, using a Multiple Input Single Output (MISO) fuel cell cooling system to regulate the internal body temperature of a PEMFC intended for transportation. The cooling system plant is taken from a recently developed hydrogen/air PEMFC total system model. It is linearized and used to design a series of controllers via μ-synthesis. μ-synthesis is chosen since system nonlinearities can be handled as parameter uncertainties. A controller must coordinate the desired fuel cell internal temperature and commanded mass flow rates of the coolant and cooling air. Each linear controller is created for a segment of the expected current density range. Plant parameters are expected to vary over their linearized values in each segment. Also, a common set of μ-synthesis weighting functions has been developed to ease controller design at different operating points. Thus, the nonlinear cooling subsystem can be controlled with a series of current density scheduled linear controllers. Current density step change simulations are presented to compare the controller closed loop performance and open loop response which uses cooling system flow rates taken from an optimal steady state solution of the whole fuel cell system. Furthermore, a closed loop sinusoid response is also given. These show that the closed loop driven internal fuel cell temperature will vary little during operation. However, this will only be true over the range that the cooling system is required to be active.


2018 ◽  
Vol 1 (1) ◽  
pp. 65-74
Author(s):  
Tomaz Martini ◽  
Jürgen Ripperger ◽  
Urs Albrecht

The interplay between the circadian system and metabolism may give animals an evolutionary advantage by allowing them to anticipate food availability at specific times of the day. Physiological adaptation to feeding time allows investigation of animal parameters and comparison of food anticipation between groups of animals with genetic alterations and/or post pharmacological intervention. Such an approach is vital for understanding gene function and mechanisms underlying the temporal patterns of both food anticipation and feeding. Exploring these mechanisms will allow better understanding of metabolic disorders and might reveal potential new targets for pharmacological intervention. Changes that can be easily monitored and that represent food anticipation on the level of the whole organism are a temporarily restricted increase of activity and internal body temperature.


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