Daniel E. Lemons

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In this paper the conceptual three-layer representation of surface tissue heat transfer proposed in Weinbaum, Jiji and Lemons [1], is developed into a detailed quantitative model. This model takes into consideration the variation of the number density, size and flow velocity of the countercurrent arterio-venous vessels as a function of depth from the skin(More)
This study was undertaken to gain a better understanding of the fundamental mechanisms of micro- and macrovascular heat transfer by experimentally identifying those vessels most important in the process. Tissue temperature fields around thermally nonequilibrated vessels were determined using a small temperature sensor that was guided through the rabbit(More)
A new theoretical model supported by ultrastructural studies and high-spatial resolution temperature measurements is presented for surface tissue heat transfer in a two-part study. In this first paper, vascular casts of the rabbit thigh prepared by the tissue clearance method were serially sectioned parallel to the skin surface to determine the detailed(More)
Theoretical studies have indicated that a significant fraction of all blood-tissue heat transfer occurs in artery-vein pairs whose arterial diameter varies between 200 and 1000 microns. In this study, we have developed a new in vivo technique in which it is possible to make the first direct measurements of the countercurrent thermal equilibration that(More)
Previous models of rat tail heat transfer have assumed that the tail is uniformly perfused along its length and have introduced questionable assumptions about the heat transfer role of the major axial arteries and the venous blood shunting between the superficial and deep veins. The recent experiments of Lemons and Wu have shown that (i) perfusion of the(More)
A new experimental approach was developed to obtain the first direct measurements of the axial countercurrent thermal equilibration in a microvascular tissue preparation using high resolution infrared thermography. Detailed surface temperature measurements were obtained for an exteriorized rat cremaster muscle in which pharmacological vasoactive agents were(More)
This study attempts to measure the hyperthermic response of individual microvessels in skeletal muscle tissue subject to local heating and then to predict the enhancement in thermal conductivity that results from the observed changes in vascular diameter and flow. In contrast to existing studies, which have tried to relate changes in tissue thermal(More)
OBJECTIVES To quantify the relative contributions of the rate of change and the magnitude of shear stress to endothelium-mediated arteriolar dilation. METHODS A feedback control system was designed in which shear stress (tau) and the temporal shear gradient (TSG) were prescribed and dynamically controlled in isolated rat cremaster 1A arterioles. The TSG(More)
We set out to develop an anatomy and physiology (A&P) curriculum with a content that was relevant and well rationalized. To do this, we developed a benchmarks curriculum process that helps us to determine what our students need to learn in A&P and then to make sure there is alignment between those learning objectives and what we teach and how we assess our(More)
A new prototype model for whole limb heat transfer is proposed wherein the countercurrent heat exchange from the large central arteries and veins in the core of the limb is coupled to microvascular models for the surrounding muscle and the cutaneous tissue layers. The local microvascular temperature field in the muscle tissue is described by the bioheat(More)