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In this thesis we examine some of the interesting aspects of the Wess-Zumino- Novikov-Witten model when this model has been gauged and its energy tensor twisted by the addition of the derivative of one of its Cartan subalgebra valued currents. Specifically we consider the group valued model with the group taken as 5^(211) which is the Lie super group used to describe N = 2 supersymmetry. This model is advocated as being a good and natural description of the N = 2 superstring (also known as the charged spinning string, or N = 2 fermionic string) when it tensors an additional topological system of ghosts. The evidence for this assertion is presented by gauging and twisting the model and then extracting the N = 2 super Liouville action by the method of Hamiltonian reduction. The connection between the 5L (2|1)/5L (2|1) Wess-Zumino-Novikov-Witten model and field theory is made through its current algebra. As is true of many super groups there exists more than one interpretation of the Dynkin diagram for the algebra of 5L(2|1) and this results in more that one set of currents for this model. The classical and quantum currents in free field form are found in both cases, as is the highly non-linear transformation by which the two sets of currents are related. An analysis of a section of the cohomology of physical states of the model is undertaken. It is shown that the additional topological ghost system that tensors the gauged, twisted SL (2\l) model when it describes the N = 2 string only contributes a vacuum state to the overall cohomology, so reducing the analysis. As the 5L(2|1)/5L(2|1) Wess-Zumino-Novikov-Witten model is a topological field theory its spectrum of physical states lie in the cohomology class defined with respect to the BRST charge. The spectrum formed from the free field currents composes the so called Wakimoto module and this is calculated via the BRST formalism.

Brown and York's gravitational microcanonical density of states is extended to general spacetime dimension and shown to be dependent upon features of the 4 dimensional gravitational action for its interpretation. Black hole entropy is calculated from the density of states path integral in general spacetime dimension, and the interpretation is shown to be likewise dependent upon the dimension of spacetime. The entropy of de Sitter and Rindler horizons are calculated using the black hole density of states and the notion of local horizon entropy density is shown to be supported. The applicability of the microcanonical ensemble to black hole mechanics is discussed at a fundamental level focussing on the absence of angular velocity as an external parameter in the gravitational Hamiltonian. The rotational ensemble and a new ensemble - the angular momentum ensemble - are introduced following Jaynes' information theory approach to statistical mechanics and proposed as more compelling candidates to calculate black hole entropy as a function of state. A program to calculate the density of states path integral non-perturbatively using causal dynamical triangulations is initiated. Regge calculus expressions for extrinsic curvature are extended to the case of Lorentzian hypersurfaces and used to derive Regge calculus expressions for quasilocal energy-momentum. The Regge version of the black hole density of states action is derived and specialised to the 3d and 4d spacetime constructions of causal dynamical triangulations. Finally, the recent suggestion that entropy is observer dependent is shown to be incompatible with the Tolman law for the equilibrium temperature in a gravitational field.

Since its first measurement in 1679, the usefulness of the location of whole body centre of mass (COM) data has progressed from having largely theoretical value into being an instrument with several diagnostic and applied scientific uses. This thesis describes first the biomechanical and measurement theory foundation of COM research and then details the historical development of methods to measure COM location and the various applied uses of this variable. Original research data presented in this thesis then go on to provide the first direct measurements of COM movement in walking humans. A second study quantifies the accuracy of the most commonly used current technique to quantify COM location (the kinematic segmental method) by determining the limits of agreement between it and a direct measurement method (the reaction-board), in lying and running subjects. In the latter studies a novel reaction-board measurement method is developed making use of life-sized projections of subjects in various stride positions and used to place runners into recumbent static running positions. These data demonstrate that reaction-board and segmental methods report COM locations with a mean difference of 1.6cm and agree to within limits of 6.0cm for the location of COM in recumbent individuals. The final study described in this thesis compares single COM measurements made using two kinematic segmental methods (models) to a direct suspension technique of measuring COM location. The suspension technique used is adapted from the original method of determining COM location upon which kinematic segmental methods derive their origin. The data show that both cadaver-derived kinematic models of COM, and kinematic models derived from live human data, differ from a direct COM suspension method, and that cadaver based estimates display greater accuracy (agreement with the direct suspension method). This study also uniquely provides information on the effect of whole body mass, body fat or body water on the accuracy of segmental models in male subjects.

Includes copies of articles co-authored by the author during the preparation of this thesis. Includes bibliographical references (leaves 233-245). A three-field photometer was employed at the University of Adelaide's Buckland Park field site to collect optical observations of the 557.7nm OI and 730nm OH airglow emissions on an almost continuous basis since May 1995 to May 2000, with observations made whenever the moon was not up.

Includes copies of articles co-authored by the author during the preparation of this thesis. Includes bibliographical references. Electronic publication; full text available in PDF format; abstract in HTML format. A three-field photometer was employed at the University of Adelaide's Buckland Park field site to collect optical observations of the 557.7nm OI and 730nm OH airglow emissions on an almost continuous basis since May 1995 to May 2000, with observations made whenever the moon was not up. Electronic reproduction.[Australia] :Australian Digital Theses Program,2001.

This thesis involves the interpretation of gravity and other potential field anomalies caused by layers of varying thickness. The partial differential equations of potential field theory are reviewed for gravitational and magnetic force fields. A similar review is carried out for steady-state heat transport and diffusion processes. For the gravitational force fields, solutions of the partial differential equations are listed in integral form for the following cases: single body with given constant density, infinitely thin sheet with variable mass density, two homogeneous layers with a slowly undulating interface and two layers with a vertically-constant-density lower layer. The solutions give the gravity anomaly in terms of the parameters of the source body. Heat transport phenomena of a similar nature are also discussed. The general expression obtained for the two homogeneous layers with a slowly undulating interface is used as an integral equation and applied to the derivation of crustal thickness variation in Oregon on the basis of two different computational methods. The first method, called the digitized algebraic method, solves the quasi-linearized form of the general integral equation by an iterative technique for three reference va1ues of the mean depth of the crust-mantle interface, viz., 25 km, 30 km, and 35 km. The second approach, called the second derivative approximation method, gives a solution by the Fourier transform technique to the linearized form of the general integral equation for the same three reference values of the mean depth of the crust-mantle interface. The above results as to the depth of the crust-mantle interface are compared with recent results with seismic refraction and dispersion data obtained along a profile in eastern Oregon. The value of the reference depth d which best reconciles with the above results and the seismic results turns out to be 30.25 km for the depth data on the basis of the algebraic method and 28.90 km for the depth data obtained with the second derivative approximation method. / Graduation date: 1972

As trade among members of the European Union (EU) is now free of tariffs, the harmonization of technical regulations or standards has become an important issue for deeper integration of the internal market. A previous analysis of the completion of the Single Market calculated that in 1996 about 80% of intra-EU trade was been affected by harmonization of technical regulations. A major objective of this thesis is to examine to what extent harmonization of regulations has reduced the so called border effect. After a brief survey of the gravity literature, we propose and test some economic and econometric extensions of the standard gravity model. This model is then applied to total manufacturing as well as to more detailed levels corresponding to different harmonization approaches. We find that harmonization of technical regulations has a positive impact on imports of total manufacturing. However, this hardly explains the importance of border effects within the EU. This result is supported at a more disaggregated level when we distinguish between manufacturing sectors according to the type of EU harmonization including the category where technical barriers do not apply. In addition, sectors where harmonization is of minor importance exhibit smaller border effects. The last part of the thesis examines, with particular reference to EU and enlargement, how environmental regulations at the national and EU level have collided and affected exports. The major findings are that more harmonization has been accompanied by higher levels of domestic environmental regulations in candidate countries. In addition, the level of domestic environmental regulations - when treated endogenously - has a larger negative effect on EU exports. We employ a newly constructed data set that contains information at the three digit level of manufacturing industries. For each industry we identify the dominant harmonization approach used by the European Commission to the removal of technical barriers to trade in the EU.