Investigations of the thermal properties of human and animal tissues

The work presented in this thesis was carried as part of a project to improve the analysis of clinical data obtained by microwave thermography. For microwave thermography measurements to be usefully interpreted for detecting thermal anomalies in the human body at depths of up to several centimetres, the thermal and microwave dielectric properties of tissues must be known. This thesis is mainly concerned with the measurement and interpretation of the values of the thermal conductivity and diffusivity of human and animal tissues. The thermal properties of biological tissue are required, in conjunction with a bio-heat equation, to allow the formation of computational models to simulate the temperature distribution inside the human body. These computational models are also useful in the analysis of tomographic temperature measurements, and are essential to ensure accurate heating in hyperthermia. The Pennes conventional bio-heat equation has proven to be successful in analysing the data produced by microwave thermography. The thermal properties of biological soft tissue are dependant on the tissue water content. Water is a major constituent of most soft biological tissues, and it has a higher thermal conductivity and thermal diffusivity than any other constituent of biological tissue. The thermal properties of biological tissue can be modelled using a mixture equation, which describes the behaviour of a two phase system in terms of the thermal properties of the individual constituents and their relative volume fractions. This allows the variation of the thermal properties of biological tissue with water content to be analysed. A self-heating thermistor probe system was used in this study to measure the in-vitro thermal conductivity and thermal diffusivity of a wide variety of human and animal tissues. The system was calibrated using glycerol and agar-gelled water since the thermal behaviour of these materials and mixtures of these materials was well known. The calibration data was examined to determine the accuracy of the calibration and to determine if there was a relationship between the observed thermal conductivity and thermal diffusivity which was generated by the measurement syste

Uterine Vascular Permeability, Extracellular Fluid Volume And Blood Flow Following Deciduogenic Stimulation Of Rats

The present study examined the possible importance of uterine vascular permeability (VP), extracellular fluid volume (ECFV) and blood flow (BF) in the enhanced accumulation of serum proteins in uterine tissue destined to undergo decidualization. This process is identifiable by endometrial blueing after intravenous (i.v.) injection of Evans blue dye. It was hypothesized that VP, ECFV and BF must increase to promote the enhanced intrauterine accumulation of serum proteins and that these uterine vascular and perivascular changes require optimal endometrial sensitization and prostaglandins (PGs).;ECFV was estimated by the uterine volume of distribution of i.v. injected {dollar}\sp{lcub}51{rcub}{dollar}Cr-EDTA, VP by the rate of increase of the uterine volume of distribution of albumin after i.v. injection of {dollar}\sp{lcub}125{rcub}{dollar}I-albumin, and BF by the microsphere technique. In one experimental manipulation, unilateral, artificial deciduogenic stimulation was given to the uteri of rats after either optimal or suboptimal sensitization for decidualization. In another manipulation, decidualization was first inhibited by intrauterine infusion of indomethacin (IM) then reinstated by simultaneous infusion of prostaglandin E{dollar}\sb2{dollar} (PGE{dollar}\sb2{dollar}) with the IM.;When stimulation was given to an optimally sensitized uterus, both VP and ECFV were significantly higher in stimulated than nonstimulated horns during the time when the endometrial blueing reaction can be demonstrated by i.v. injection of Evans blue dye. VP became significantly increased by 4 hours after stimulation while significant increases in ECFV followed at 8 hours. Deviation from optimal sensitization and infusion with IM eliminated or significantly reduced the elevated ECFV and VP in simulated horns. This effect of IM was reversed by coinfusion with PGE{dollar}\sb2{dollar}. In most cases, increases in total BF were proportional to increases in uterine weight producing consistent uterine tissue BF (3-4 {dollar}\mu{dollar}l/min/mg). Excessive estrogen sensitization and coinfusion of PGE{dollar}\sb2{dollar} and IM for 20 hours resulted in uterine weight gains which were not accompanied by proportional increases in total uterine BF. For these treatments, uterine tissue BF was significantly reduced.;The results of this study indicate that transient increases in uterine VP and ECFV occur during the time when the uterine blueing reaction can be demonstrated. The fact that uterine VP and ECFV nearly always changed in parallel suggests that these variables are either directly related or share a common control element. However, the possibility that the 2 variables play independent roles in the uterine blueing reaction cannot be excluded. Increased uterine BF does not appear to be an essential component of the blueing phenomenon. The use of contrast-enhanced magnetic resonance imaging techniques provided identification of predecidual tissue in dissected uteri and in the uteri of intact, anaesthetized rats. The elevated ECFV in predecidual tissue appears to be largely responsible for the image enhancement

The interior structure of rotating black holes 1. Concise derivation

This paper presents a concise derivation of a new set of solutions for the interior structure of accreting, rotating black holes. The solutions are conformally stationary, axisymmetric, and conformally separable. Hyper-relativistic counter-streaming between freely-falling collisionless ingoing and outgoing streams leads to mass inflation at the inner horizon, followed by collapse. The solutions fail at an exponentially tiny radius, where the rotational motion of the streams becomes comparable to their radial motion. The papers provide a fully nonlinear, dynamical solution for the interior structure of a rotating black hole from just above the inner horizon inward, down to a tiny scale.Comment: Version 1: 8 pages, 3 figures. Version 2: Extensively revised to emphasize the derivation of the solution rather than the solution itself. 11 pages, 4 figures. Version 3: Minor changes to match published version. Mathematica notebook available at http://jila.colorado.edu/~ajsh/rotatinginflationary/rotatinginflationary.n

Cyclic Proofs and Coinductive Principles

It is possible to provide a proof for a coinductive type using a corecursive function coupled with aguardedness condition. The guardedness condition, however, is quiterestrictive and many programs which are in fact productive and do not compromise soundness will be rejected. We present a system of cyclic proof for an extension of System F extended with sums, products and (co)inductive types. Using program transformation techniques we are able to take some programs whose productivity is suspected and transform them, using a suitable theory of equivalence, into programs for which guardedness is syntactically apparent. The equivalence of the proof prior and subsequent to transformation is given by a bisimulation relation.

Soft spin correlations in final-state parton showers

We introduce a simple procedure that resolves the long-standing question of how to account for single-logarithmic spin-correlation effects in parton showers not just in the collinear limit, but also in the soft wide-angle limit, at leading colour. We discuss its implementation in the context of the PanScales family of parton showers, where it complements our earlier treatment of the purely collinear spin correlations. Comparisons to fixed-order matrix elements help validate our approach up to third order in the strong coupling, and an appendix demonstrates the small size of residual subleading-colour effects. To help probe wide-angle soft spin correlation effects, we introduce a new declustering-based non-global spin-sensitive observable, the first of its kind. Our showers provide a reference for its single-logarithmic resummation. The work in this paper represents the last step required for final-state massless showers to satisfy the broad PanScales next-to-leading logarithmic accuracy goals.Comment: 26 pages, 12 figure

Matching and event-shape NNDL accuracy in parton showers

To explore the interplay of NLO matching and next-to-leading logarithmic (NLL) parton showers, we consider the simplest case of γ* and Higgs-boson decays to qq¯¯and gg respectively. Not only should shower NLL accuracy be retained across observables after matching, but for global event-shape observables and the two-jet rate, matching can augment the shower in such a way that it additionally achieves next-to-next-to-double-logarithmic (NNDL) accuracy, a first step on the route towards general NNLL. As a proof-of-concept exploration of this question, we consider direct application of multiplicative matrix-element corrections, as well as simple implementations of MC@NLO and POWHEG-style matching. We find that the first two straightforwardly bring NNDL accuracy, and that this can also be achieved with POWHEG, although particular care is needed in the handover between POWHEG and the shower. Our study involves both analytic and numerical components and we also touch on some phenomenological considerations

Entropy creation inside black holes points to observer complementarity

Heating processes inside large black holes can produce tremendous amounts of entropy. Locality requires that this entropy adds on space-like surfaces, but the resulting entropy (10^10 times the Bekenstein-Hawking entropy in an example presented in the companion paper) exceeds the maximum entropy that can be accommodated by the black hole's degrees of freedom. Observer complementarity, which proposes a proliferation of non-local identifications inside the black hole, allows the entropy to be accommodated as long as individual observers inside the black hole see less than the Bekenstein-Hawking entropy. In the specific model considered with huge entropy production, we show that individual observers do see less than the Bekenstein-Hawking entropy, offering strong support for observer complementarity.Comment: 13 pages. This is a companion paper to arXiv:0801.4415; Added reference