Operating theatre photography for orthopaedics and aesthetic surgery.

The aim of this paper is to examine the author's personal experience and practice in operating theatre photography. The ways of working are personal to the author but hopefully will help others in undertaking this type of work

Evaluation of commercial GaN HEMTs for pulsed power applications

A non-conformally invariant coupling between the inflaton and the photon in the minimal Lorentz-violating standard model extension is analyzed. For specific forms of the Lorentz-violating background tensor, the strong-coupling and back-reaction problems of magnetogenesis in de Sitter inflation with scale $${\sim }10^{16}\,\hbox {GeV}$$ are evaded, the electromagnetic-induced primordial spectra of (Gaussian and non-Gaussian) scalar and tensor curvature perturbations are compatible with cosmic microwave background observations, and the inflation-produced magnetic field directly accounts for cosmic magnetic fields

Large N and the renormalization group

In the large N limit, we show that the Local Potential Approximation to the flow equation for the Legendre effective action, is in effect no longer an approximation, but exact - in a sense, and under conditions, that we determine precisely. We explain why the same is not true for the Polchinski or Wilson flow equations and, by deriving an exact relation between the Polchinski and Legendre effective potentials (that holds for all N), we find the correct large N limit of these flow equations. We also show that all forms (and all parts) of the renormalization group are exactly soluble in the large N limit, choosing as an example, D dimensional O(N) invariant N-component scalar field theory.Comment: 13 pages, uses harvmac; Added: one page with further clarification of the main results, discussion of earlier work, and new references. To be published in Phys. Lett.

The ability and willingness to pay for low-cost housing: Household experiences in the Faux au Chaud Settlement in Castries, St. Lucia

This research integrates the elements of affordability, household socio-demographic change and housing improvement in understanding how low-income households establish the ability and willingness to pay for low-cost housing at any conjuncture. In order to do this the researcher firstly examined how the concept of affordability has been applied since 1974, to the design and production of low-cost housing in Developing Countries and the associated issues involved. It is established from existing literature that housing programmes based on this concept have had limited success in providing housing access for the majority of low income households below the 40th income percentile. The problem appears to relate to the inability to establish levels of housing affordability as a consequence of the invalidity of assumptions and the definitional, measurement and operational inadequacies as gleaned from existing literature. Further, it is the view of this research that this inability is also due to the failure of housing programme designers to take cognizance of the impact of the social and demographic attributes in the establishment of the ability and willingness to pay for housing at specific conjuncture. These issues have led to the apparent non-correspondence between the housing solutions developed based on the concept and the households'ability and willingness to pay for them. The challenge remains as that of 1) finding appropriate housing supply responses to match the varying levels of the ability and willingness to pay which are thought to exist among these households and 2) determining how low-income households establish their ability and willingness to pay for housing. For this research the latter area of this challenge which is the concern of this research, must be determine if the former is to be resolved. This is done by examining the housing experiences of households to determine when and how they actually establish the ability and willingness to pay. This research therefore employed a user-determined approach among a casestudy population of urban, low-income squatter households in Castries, St Lucia. From this study, it is hoped that guiding principles might be derived to inform the design of low-cost housing programmes

Derivative expansion of the renormalization group in O(N) scalar field theory

We apply a derivative expansion to the Legendre effective action flow equations of O(N) symmetric scalar field theory, making no other approximation. We calculate the critical exponents eta, nu, and omega at the both the leading and second order of the expansion, associated to the three dimensional Wilson-Fisher fixed points, at various values of N. In addition, we show how the derivative expansion reproduces exactly known results, at special values N=infinity,-2,-4, ... .Comment: 29 pages including 4 eps figures, uses LaTeX, epsfig, and latexsy

O(N) models within the local potential approximation

Using Wegner-Houghton equation, within the Local Potential Approximation, we study critical properties of O(N) vector models. Fixed Points, together with their critical exponents and eigenoperators, are obtained for a large set of values of N, including N=0 and N\to\infty. Polchinski equation is also treated. The peculiarities of the large N limit, where a line of Fixed Points at d=2+2/n is present, are studied in detail. A derivation of the equation is presented together with its projection to zero modes.Comment: 27 pages, LaTeX with psfig, 7 PostScript figures. One reference corrected and one added with respect to the journal versio