Variable Speed of Light Cosmology and Bimetric Gravity: An Alternative to Standard Inflation

A scalar-tensor bimetric gravity model of early universe cosmology is reviewed. The metric frame with a variable speed of light (VSL) and a constant speed of gravitational waves is used to describe a Friedmann-Robertson-Walker universe. The Friedmann equations are solved for a radiation dominated equation of state and the power spectrum is predicted to be scale invariant with a scalar mode spectral index $n_s=0.97$. The scalar modes are born in a ground state superhorizon and the fluctuation modes are causally connected by the VSL mechanism. The cosmological constant is equated to zero and there is no significant dependence on the scalar field potential energy. A possible way of distinguishing the metric gravity model from standard inflationary models is discussed.Comment: 10 pages. Latex file. No figures. Talk given at the Coral Gables Conference on High Energy Physics and Cosmology, Fort Lauderdale, Florida, December 17-21, 2003. Typos corrected. Reference adde

Transient and diffusion analysis of Hg Cd Te

The solution of the one dimensional planar interface solidification problem is presented. Numerical solutions are applied to experimental solute profiles to determine the effective diffusion constant for Hg Co Te. Progress on the design and construction of a high gradient furnace is reported

A Restoration Method for Impulsive Functions

A method is presented for enhancing the resolution of impulsive functions which have been degraded by a known convolutional disturbance and by the addition of white noise. An autoregressive model is employed to represent the spectrum of the ideally resolved impulsive function. The method is flexible in that it allows constraints to be incorporated into the resolution scheme. Two quite diverse examples are presented as illustration

Crustal structure of the Borderland-Continent Transition Zone of southern California adjacent to Los Angeles

We use data from the onshore-offshore component of Los Angeles Region Seismic Experiment (LARSE) to model the broad-scale features of the midcrust to upper mantle beneath a north-south transect that spans the continental borderland in the Los Angeles, California, region. We have developed an analysis method for wide-angle seismic data that consists primarily of refractions, lacks near-offset recordings, and contains wide gaps in coverage. Although the data restrict the analysis to the modeling of broad-scale structure, the technique allows one to explore the limits of the data and determine the resolving power of the data set. The resulting composite velocity model constrains the crustal thickness and location and width of the continent-Borderland transition zone. We find that the mid to lower crust layer velocities of the Inner Borderland are slightly lower than the corresponding layers in the average southern California crust model, while the upper mantle velocity is significantly higher. The data require the Moho to deepen significantly to the north. We constrain the transition zone to initiate between the offshore slope and the southwest Los Angeles Basin. If the Inner Borderland crust is 22 km thick, then the transition zone is constrained to initiate within a 2 km wide region beneath the southwest Los Angeles Basin, and have a width of 20–25 km. The strong, coherent, and continuous Pn phase suggests the Moho is coherent and laterally continuous beneath the Inner Borderland and transition zone. The Inner California Borderland seems to be modified and thickened oceanic crust, with the oceanic upper mantle intact beneath it

The measurement of applied forces during anterior single rod correction of adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is the most common form of spinal deformity in paediatrics, prevalent in approximately 2-4% of the general population. While it is a complex three-dimensional deformity, it is clinically characterised by an abnormal lateral curvature of the spine. The treatment for severe deformity is surgical correction with the use of structural implants. Anterior single rod correction employs a solid rod connected to the anterior spine via vertebral body screws. Correction is achieved by applying compression between adjacent vertebral body screws, before locking each screw onto the rod. Biomechanical complication rates have been reported as high as 20.8%, and include rod breakage, screw pull-out and loss of correction. Currently, the corrective forces applied to the spine are unknown. These forces are important variables to consider in understanding the biomechanics of scoliosis correction. The purpose of this study was to measure these forces intra-operatively during anterior single rod AIS correction

A dynamical pairing between two rational maps

Given two rational maps $\varphi$ and $\psi$ on \PP^1 of degree at least two, we study a symmetric, nonnegative-real-valued pairing which is closely related to the canonical height functions $h_\varphi$ and $h_\psi$ associated to these maps. Our main results show a strong connection between the value of and the canonical heights of points which are small with respect to at least one of the two maps $\varphi$ and $\psi$. Several necessary and sufficient conditions are given for the vanishing of . We give an explicit upper bound on the difference between the canonical height $h_\psi$ and the standard height $h_\st$ in terms of , where $\sigma(x)=x^2$ denotes the squaring map. The pairing $$ is computed or approximated for several families of rational maps $\psi$

The Initial-Value Problem of Spherically Symmetric Wyman Sector Nonsymmetric Gravitational Theory

We cast the four-dimensional field equations of the Nonsymmetric Gravitational Theory (NGT) into a form appropriate for numerical study. In doing so, we have restricted ourselves to spherically symmetric spacetimes, and we have kept only the Wyman sector of the theory. We investigate the well-posedness of the initial-value problem of NGT for a particular data set consisting of a pulse in the antisymmetric field on an asymptotically flat space background. We include some analytic results on the solvability of the initial-value problem which allow us to place limits on the regions of the parameter space where the initial-value problem is solvable. These results are confirmed by numerically solving the constraints.Comment: REVTeX 3.0 with epsf macros and AMS symbols, 18 pages, 9 figure

VLTI observations of the dust geometry around R Coronae Borealis stars

We are investigating the formation and evolution of dust around the hydrogen-deficient supergiants known as R Coronae Borealis (RCB) stars. We aim to determine the connection between the probable merger past of these stars and their current dust-production activities. We carried out high-angular resolution interferometric observations of three RCB stars, namely RY Sgr, V CrA, and V854 Cen with the mid-IR interferometer, MIDI on the VLTI, using two telescope pairs. The baselines ranged from 30 to 60 m, allowing us to probe the dusty environment at very small spatial scales (~ 50 mas or 400 stellar radii). The observations of the RCB star dust environments were interpreted using both geometrical models and one-dimensional radiative transfer codes. From our analysis we find that asymmetric circumstellar material is apparent in RY Sgr, may also exist in V CrA, and is possible for V854 Cen. Overall, we find that our observations are consistent with dust forming in clumps ejected randomly around the RCB star so that over time they create a spherically symmetric distribution of dust. However, we conclude that the determination of whether there is a preferred plane of dust ejection must wait until a time series of observations are obtained.Comment: Accepted for publication in MNRAS; 14 pages, 10 figures, 6 table