Thermal regulation

For most situations and conditions in daily life, the human can be represented adequately by a simple model that is helpful for understanding human thermal regulation. The model has two thermal compartments (Fig 5.1). The... 

The penetration of light into and through dermal tissues has important consequences. This penetration is demonstrated in Fig. 11.1. Skin, as the primary organ responsible for thermal regulation, is overperfused relative to its metabolic requirements (Anderson and Parrish, 1981). 

Liu Y, Garceau NY, Loros JJ, Dunlap JC 1997 Thermally regulated translational control of FRQ mediates aspects of temperature responses in the Neurospora circadian clock. Cell... 

JAP1090993). When the reaction is carried out on a large scale, heating the reactants to this temperature is sometimes enough to start a mild exothermal process further, thermally regulated by mere acetylene feeding. 

For example, surfaces comprising PNIPAM microgels were utilized for drug delivery [138], Electrostatic layer-by-layer assembly with poly(NIPAM-coacrylic acid) and poly(allylamine hydrochloride) on an amino-functionalized surface yielded thermoresponsive thin films. These were capable of a thermally regulated uptake and release of the chemotherapeutic drug doxorubicin. The films were loaded... 

Ward GA, Stover CK, Moss B, Fuerst TR (1995), Stringent chemical and thermal regulation of recombinant gene expression by vaccinia virus vectors in mammalian cells, Proc. Natl Acad. Sci. U S A 92 6773-6777. 

Additional evidence supporting a role for melanization in water conservation comes from a study of D. polymorpha populations in Brazil (Brisson et al., 2005). Dark flies were most abundant in open, dry environments, despite the fact that these were warmer than more humid forest habitats, where light flies predominated. In this case, melanization patterns were opposite to those expected for thermal regulation, but consistent with a role in water conservation. Thus, in combination with studies by Parkash and colleagues, there is increasing evidence that melanization significantly affects water balance, at least in Drosophila. The fact that transitions in water-loss can be observed in solvent-extracted animals (Yoder and Tank, 2006) also supports a role for non-lipid layers in determining... 

Thermosyphons are a simple devise for thermal control of sorbent bed. Very suitable new design of thermosyphon, so called vapour-dynamic thermosyphon (Fig. 13), was especially developed for thermal regulating of continuous long horizontal objects. 

Section III,A. The precision of thermal regulation obtained inside the column, held at 0° to -35°C, is 0.1°C. The temperature within the column is measured by a chromel-alumel thermocouple and galvanometer. 

Thermal regulation requires the establishment of a con-troUed-temperature environment in close contact with the reaction container and efficient heat transfer from the environment to the reaction mixture. Air baths, water baths, and contact with a heating or cooling plate (e.g., Peltier device) have been used for thermal regulation in commercial analyzers (mostly at 37 °C). 

Although some primitive oiganisms inhabiting thermally stable environments have been referred to as nominal homeotherms, this is a misnomer as such organisms are not thermal regulators at all, much less precise ones. Some dinosaurs may have been inertial homeotherms, relying on their large thermal mass (McNab, 2002). 

The pointed syndromes appear at different time periods after contact with the poison, after a hidden period of approximately 3 to 10 hours. Thermal-regulation disorders with high temperature are observed (caused by the noxa at the beginning of the intoxication and later provoked by secondary infections). 

Aldrich CG, Paterson JA, Tate JL, Kerley MS. The effects of endophyte-infected tall fescue consumption on diet utilization and thermal regulation in cattle. J Animal Sci 71 164-170, 1993. 

The temperature field in a tissue is determined by heat conduction and convection, metabolic heat generation, thermal energy transferred to the tissue from an external source or the surrounding tissue, and the tissue geometry. Thermal conduction is characterized by a thermal conductivity, k, at steady state and by a thermal diffusivity, a, in transient state. Thermal convection is characterized by the topology of the vascular bed and the blood flow rate, which is subject to the thermal regulation. 

All organisms regulate the fluidity of their membranes to maintain a membrane bilayer in a largely fluid state. As temperatures are lowered, membranes undergo a reversible change from a fluid (disordered) to a non-fluid (ordered) state. In E. coli, the temperature of the transition point depends on the fatty acid composition of the membrane phospholipids [12]. At lower temperatures, the amount of c/i-vaccenic acid is rapidly (within 30 s) increased due to the increased activity of FabF. Synthesis of mRNA and protein are not required. Mutants that lack FabF are unable to modulate their fatty acid composition in a temperature-dependent manner. Thus FabF, and not FabB, is involved in the thermal regulation of the fatty acid composition of the membranes. 

The literature dealing with thermal regulation in the human is very extensive but somewhat contradictory. Reviews (I, 2, 3) which cover earlier work in depth should be consulted for more information. Our attention will be focused on recent work in which quantitative results are developed in a form suitable for inclusion in mathematical models. 

Factors involved in thermal regulation will be considered first for near-neutral environments. Then situations which involve greater thermal stress will be considered. Special life support systems designed to enable man to perform useful work in hostile environments will be discussed. Several examples of using deep hypothermia in surgery will be presented also. The paper will conclude with a discussion of mathematical simulation of the human thermal system. 

Desmond left the thermal regulator power circuit he was testing and drifted over. 

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