8,111 research outputs found
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 . 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
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 20â25 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
An investigation to establish low-level turbulent wind definition in terms of mean micrometeorological parameters summary report, 30 apr. 1962 - 30 sep. 1963
Instrumention and measurement facility for program establishing low-level turbulent wind definition in micrometeorological term
Abelian Anomalies in Nonlocal Regularization
Nonlocal regularization of QED is shown to possess an axial anomaly of the
same form as other regularization schemes. The Noether current is explicitly
constructed and the symmetries are shown to be violated, whereas the identities
constructed when one properly considers the contribution from the path integral
measure are respected. We also discuss the barrier to quantizing the fully
gauged chiral invariant theory, and consequences.Comment: 21 pages, UTPT-93-0
Geometry and seismic properties of the subducting Cocos plate in central Mexico
The geometry and properties of the interface of the Cocos plate beneath central Mexico are determined from the receiver functions (RFs) utilizing data from the Meso America Subduction Experiment (MASE). The RF image shows that the subducting oceanic crust is shallowly dipping to the north at 15° for 80 km from Acapulco and then horizontally underplates the continental crust for approximately 200 km to the Trans-Mexican Volcanic Belt (TMVB). The crustal image also shows that there is no continental root associated with the TMVB. The migrated image of the RFs shows that the slab is steeply dipping into the mantle at about 75° beneath the TMVB. Both the continental and oceanic Moho are clearly seen in both images, and modeling of the RF conversion amplitudes and timings of the underplated features reveals a thin low-velocity zone between the plate and the continental crust that appears to absorb nearly all of the strain between the upper plate and the slab. By inverting RF amplitudes of the converted phases and their time separations, we produce detailed maps of the seismic properties of the upper and lower oceanic crust of the subducting Cocos plate and its thickness. High Poisson's and Vp/Vs ratios due to anomalously low S wave velocity at the upper oceanic crust in the flat slab region may indicate the presence of water and hydrous minerals or high pore pressure. The evidence of high water content within the oceanic crust explains the flat subduction geometry without strong coupling of two plates. This may also explain the nonvolcanic tremor activity and slow slip events occurring in the subducting plate and the overlying crust
Experimental verification of computer spray-combustion models
Analytical model formulation, representing performance of spray-combustion device, is based on understanding of atomization, mixing, vaporization, and combustion which occurs in device. Report lists results of correlations of computed values with values obtained from experiments with rocket combustor. Technique offers excellent method for evaluating validity and ranges of applicability of combustion models
Vector field mediated models of dynamical light velocity
A vector-tensor theory of gravity that was introduced in an earlier
publication is analyzed in detail and its consequences for early universe
cosmology are examined. The multiple light cone structure of the theory
generates different speeds of gravitational and matter wave fronts, and the
contraction of these light cones produces acausal, superluminary inflation that
can resolve the initial value problems of cosmology.Comment: 16 pages, uses amsar
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