Temperature modulation and local heat transfer in the microcirculation.
Item
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Title
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Temperature modulation and local heat transfer in the microcirculation.
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Identifier
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AAI9605691
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identifier
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9605691
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Creator
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Zhu, Liang.
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Contributor
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Co-Advisers: Sheldon Weinbaum | Daniel E. Lemons
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Date
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1995
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Mechanical | Engineering, Biomedical | Biology, Animal Physiology
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Abstract
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In this dissertation an experimental study was conducted to investigate axial thermal equilibration between thermally significant artery-vein pairs in two-dimensional rat cremaster muscle preparation. An accurate three-dimensional model is developed for a tissue preparation with arbitrarily embedded vessels to interpret the experimental results. The preparation was also used to measure the hyperthermic response of individual microvessels subject to local heating and the enhancement in the thermal conductivity k{dollar}\rm \sb{lcub}eff{rcub}{dollar} due to blood perfusion has been calculated for this hyperthermic response.;A brief introduction to temperature modulation and local heat transfer in the microcirculation is given in chapter 1. In chapter 2, a theoretical heat transfer model is developed for treating countercurrent vessels arbitrarily embedded in a tissue preparation. This solution was used to guide the design of our experimental study. In chapter 3, a new experimental approach is described for obtaining the first direct measurements of the axial thermal equilibration in a rat cremaster muscle preparation using high-resolution infrared thermography. Detailed surface temperature measurements were obtained from this preparation in which drugs were employed to change the local blood flow Peclet number in the feeding artery. The theoretical model developed in chapter 2 is modified to include axial conduction in the tissue and the presence of the supporting glass slide to interpret the experimental results. The theoretical model also predicts the range of conditions in which conduction or countercurrent blood flow is the dominant mode for axial thermal equilibration.;Chapter 4 describes the use of the rat cremaster muscle to study the dynamic vasomotor response of the microcirculation to local heating. Experimental studies were performed on 1A, 2A, 3A and 4A arterioles to assess the measurements of the in vivo changes in blood flow when the temperature was raised from 34 to 42 {dollar}\sp\circ{dollar}C. These experimental measurements were used to evaluate the Weinbaum-Jiji expression for k{dollar}\rm \sb{lcub}eff{rcub}{dollar}. The theory predicts that significant enhancement in k{dollar}\rm \sb{lcub}eff{rcub}{dollar} starts to occur for vessels larger than 70{dollar}\mu{dollar}m dia.. Results also indicate that the Weinbaum-Jiji expression for k{dollar}\rm \sb{lcub}eff{rcub}{dollar} is valid in cremaster muscle for both normal and hyperthermic conditions provided the largest vessels are {dollar}<{dollar}200{dollar}\mu{dollar}m dia..
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
