A critical survey of aspects of our knowledge of the heat of formation of the benzyl radical is given in view of its relevance to the heat change in the dissociation process:- C6H5CH3 + C6H5CH2- + H- (2) Previous work on the pyrolysis of toluene by flow techniques in summarized and apparatus devised to study the reaction under more defined conditions with independent variation of reaction time and partial pressure. Analytical investigations were extended to continuous observation of hydrogen production, and mass spectrometry was applied to identification of gases, liquids and solids. (3) The existence of the postulated reaction:- H- + C6H5CH3 = C6H6 + CH3- has been checked by decomposing toluene and fluorine together in the flow system. The latter substances provides excess hydrogen atoms, and an increase in decomposition was observed. (4) Decompositions of toluene in the presence of deuterium have shown that products and unchanged reactant all show appreciable deuteration, and it seems that extensive exchange reactions, probably initiated by hydrogen and deuterium atoms, occur at a rate faster than the decomposition process as judged by (hydrogen + methane) formation. (5) The products of the reaction not condensable in liquid air averaged 76.7% hydrogen and 23.3% methane. In addition to methane, ethane and ethylene have been shown to be present in appreciable amounts. The liquid products contained benzene, but not in amount equivalent to the methane and C2-hydrocarbons found to be present. The solid products have been shown, by the application of mass spectrometry to a few milligrams of product, to include the following substances in the molar proportions indicated:- 50-60 mole percent dibenzyl, 1-2 mole percent diphenyl, and the remainder dimethyldiphenyls and monomethyldiphenyls in the ratio 4:1. (6) The kinetic data on the reaction have been obtained within the following range of conditions:- 772-880°c; reaction times 0.565 - 2.076 seconds; toluene partial pressures 0.56 - 2.34 mm.; total gas pressure 3.33- 10.73 mm. The carrier gases have included nitrogen, helium and deuterium. A small number of experiments in a static system extended the temperature range to 750°c. (7) It has been shown that, judged by the (hydrogen + methane) production, the reaction was first order over the range of flow system variables indicated in (6). In order to get consistent data 'seasoning' of the reaction vessel was essential, and this process was followed by application of a thermal conductivity gauge method. (8) The temperature dependence of the first order rate constants was given by log.10k(sec−1) =-84700/2.303RT +15.1. (9) The results of this work have been compared at relevant points with previous data. It is concluded that Szwarc's views on the simple nature of the processes occurring cannot be maintained. Steacie's criticisms of Szwarc's findings are substantiated even within the latter's temperature range of investigation. It is not felt possible to assert that the experimental activation energy quoted in (8) is the bond dissociation energy for the side chain C-H bond in toluene. It may be the case since it is in agreement with recent independent determinations of the heat of formation of the benzyl radical, but the complexities of the products weaken the case.

In this thesis, immunological parameters in multiple sclerosis patients (MS) have been examined and techniques contributing to the study of these aspects have been developed. The epidemiology of MS suggests that both environmental and genetic factors contribute to the disease process. According to a widespread theory, an autoimmune reaction leading to demyelination could be induced, in genetically determined individuals, by an infectious agent (s) e.g a paramyxovirus or a retrovirus. In the first part of the thesis, the oligoclonal immunoglobulin (Igs) in the CSF of MS patients in relation to the paramyxovirus SV5 were studied. This was to complement an initial observation made in the department that a significant proportion of cerebrospinal fluids (CSF) could have oligoclonal bands directly acting against antigens (Ags) of this virus. In the second part of the thesis, techniques were developed for the analysis of proliferative capacity of peripheral lymphocytes of MS and control patients using possible MS autoantigens viz myelin and brain vessels. The humoral response against these Ags was also assessed by immunoblotting using MS, neurological and normal control patients. In parallel and in the view to obtaining antigens for the immunological studies, techniques for the purification and characterisation of human brain vessels from post mortem brains were assessed and attempts to culture human brain endothelial cell lines were made.

A turtle geometric construction on the plane, called a polynomial generated polygon (PGP) and represented by Pf,pm, is generated from the sequence obtained from evaluating f(x) ∈ Z[x] over Z modulo pm where p is a prime and m ∈ N. Computational methods are developed to pre-calculate the symmetries exhibited by Pf,pm for a given f and pm. These include procedures to find whether Pf,pm is bounded or unbounded, the degree of rotational symmetry present, whether lines of reflectional symmetry can be observed, and in the case of Pf,pm unbounded, whether the PGP has a glide reflection. Methods are also sought to find a suitable f and pm to produce a desired 'feasible' shape in a PGP construction, and how the same shape might be generated modulo pm+k if it cannot be produced modulo pm.

This thesis investigates the ducting of magnetoacoustic waves in coronal structures. The propagation of waves in current sheets and coronal loops has been examined in order to understand wave ducting in structured plasmas, and to provide an explanation of the observed oscillatory behaviour in the solar corona. Firstly a comprehensive review of the observations of loops and oscillations in the corona is given. An investigation into how the curvature of the loop alters the ducting of magnetoacoustic waves is then presented by studying the effect of the length, width and the density enhancement of the loop and also the frequency of oscillation. The effect of the curvature is to generate wave leakage from the loop. The guiding of magnetoacoustic waves by a current sheet is also considered. An investigation into the type of modes which may propagate and the time scales of oscillation is performed. Impulsively generated waves exhibit similar temporal signatures to observations of X-ray and radio emission. Periods of oscillation for all the ducted wave models are in good agreement with reported observations. The effect of a random boundary motion on a magnetospheric cavity is examined through numerical simulations. A broadband driving spectrum excites the quasi-monochromatic fast modes whose frequencies lie within the driving spectrum. These fast modes couple to an Alfvén mode if the frequency lies within the Alfvén continuum. The position of the resonant field lines and the Alfvén mode eigenfunction may be accurately calculated by assuming a periodic boundary motion. To conclude the work in this thesis the three-dimensional magnetic topologies surrounding neutral points are studied. The local linear magnetic structure about the null is found to depend only on a 3 X 3 matrix containing four parameters. The type of topology is dependent upon the nature of the eigenvalues and eigenvectors of this matrix.

A study was made with the objectives: 1. Evaluation of a micro-adsorption detector for use in liquid chromatography. 2. Evaluation of a micro-adsorption detector for use in gas ch.ranatography. 3. Investigation of the micro-adsorption cell as a tool for screening chromatographic systems, in adsorption studies, and as a micro-calorimeter. The micro-adsorption detector was found to have sufficient sensitivity to detect nanogram quantities of a component in either a liquid or gaseous carrier, and to have a linear dynamic range of 10²-10³. These qualities, combined with the selectivity of the detector indicate its usefulness in both liquid and gas chromatographic operations. The major limitation to its use is the characteristic adsorption/desorption responsive curve, which requires increased column lengths or resolution over other detectors such as the UV detector. In addition a semi-quantitative correlation between MAD response and chromatographic retention times indicates that the detector has significant potential as a screening tool for separation systems. By means of a calibration apparatus the detector response was characterized in terms of heat flux and temperature differential, and heats of absorption were calculated at concentrations of 10⁻⁴- 10⁻⁶ molar. These compared favorably with those literature values which were available close to these concentrations. / Ph. D.

The continental crust is the archive of Earth history. Much of what we know about the development of Earth is learned from the continental crust, and it is within the crust that many natural resources are found. Hence, understanding its formation and evolution is a key aspect to a deeper knowledge of the Earth system. This thesis is a study of the processes that have formed and shaped the distribution of continental crust, with specific focus on crustal development associated with the Rodinian supercontinent and the Grenville Orogeny spanning ca. 1200 to 900 Ma. Specifically it addresses an aspect of the incompleteness of the record of continental crust formation. The preserved continental crust is punctuated with periods of lesser and greater frequency of geologic features, e.g., the temporal distribution of the ages of mineral deposits, juvenile granitoids, eclogites, granulites, and the U-Pb crystallization ages of zircons now preserved in modern and ancient sediments (see Gastil, 1960; Barley and Groves, 1992; Condie, 1998; Campbell and Allen, 2008; Brown, 2007; Bradley, 2011). In addition, interpretive features in the geologic record also have an apparent episodic distribution such as passive margins (Bradley, 2011) and supercontinents (Condie, 1998). The episodic nature of these geologic phenomena implies either an episodic formation or preferential preservation of continental crust. These two end member models have been explained through a number of geologic processes such as eruption of superplumes, global disruption of thermal structure of the mantle, assembly of supercontinents, collisional orogenesis. Through the chapters outlined below, this thesis explores the connection of these episodic geologic events with key isotopic signals, principally U-Pb, Hf, and O isotopes in zircon supplemented by sedimentology, structural geology, and igneous geochemistry. It comprises a series of chapters developed around manuscripts prepared for publication.

No description available.

This thesis contains a critical discussion of two metaethical theories: expressivism, as developed in the works of Simon Blackburn, and Cornell realism, as presented by Richard Boyd and David Brink. In the introduction, a distinction is made between external and internal accommodation projects for moral discourse and it is argued that the external accommodation project should be guided by acceptance of methodological naturalism. Expressivism and Cornell realism are then subjected to an extended comparative evaluation, and an answer is sought to the question of which of the two should be favoured. The main conclusion of the thesis is that Cornell realism is rationally preferable to expressivism. This conclusion is arrived at by looking at how well the two theories, respectively, explain various deeply embedded features of moral discourse. Explaining such features is what the internal accommodation project for moral discourse consists in. The assertoric surface-form of moral discourse and the supervenience of moral predicates on natural predicates receive special attention in the study. It is argued that expressivism and Cornell realism do equally well on the issue of moral supervenience. But whereas expressivism is still vulnerable to a particular argument from the philosophy of language (the Frege-Geach point), Cornell realism can fend off the criticism that most persistently has been directed at it from this area of philosophy. In a comparative evaluation involving the selected issues, Cornell realism therefore fares better than expressivism.

The primary concern of this thesis is to investigate what light (if any) the theory of rational decision can throw on certain problems in first-order ethics. In particular, it examines whether given a correct theory of decision we can determine which of the two major rivals in the field of contemporary ethics, utilitarianism and contractarianism, is the more adequate moral theory. I begin by outlining what I call orthodox decision theory and note from this theory together with a minimal characterization of what it is to make a moral judgement we can deduce utilitarianism. The apparent conflict between utilitarianism and our moral intuitions is then examined. I criticize a common response made by utilitarians to this conflict, namely, their recourse to the distinction between rule and act utilitarianism. But I then ask the question of whether this conflict really matters? I conclude that in a sense it does not. I then turn from a consideration of the implications of utilitarianism to its foundations, particularly, its foundations in orthodox decision theory. I attempt to establish that orthodox theory has empirical content and that it has been falsified. I also consider the theory from the normative standpoint and construct a prima facie case against it. I now consider the dispute between the contractarian and the utilitarian and note that it is essentially decision theoretic in character. From a consideration of what was found to be mistaken about orthodox theory I now argue for a defence of the selection rule for rational choice presupposed by contractarianism and thereby offer a (partial) defence of a contractarian theory of justice.

Induction of an adaptive, or antigen specific, immune response is critical for eliminating most infections. Pathogen clearance is accomplished primarily, by the actions of CD4+ T cells through their ability to recognize foreign antigens presented at the cell surface by major histocompatibility class II (MHC II) molecules. Consequently, the capacity to regulate expression of MHC molecules is essential to control the adaptive immune response. MHC molecules are regulated at the level of transcription by a master regulator, the class II transcriptional activator, CIITA. Thus, the expression of MHC II is directly related to proper CIITA activity. This thesis focuses on the novel role of S7, an ATPase subunit of the 19S proteasome, in the transcriptional regulation of CIITA and MHC II molecules.