On the Cosmology of Massive Vector Fields with SO(3) Global Symmetry

A relevant reference ([14]) has been added.Comment: 19 pages, plain tex, DF/IST-3/92 and DFFCUL 03-5/199

Semiclassical approximation to supersymmetric quantum gravity

We develop a semiclassical approximation scheme for the constraint equations of supersymmetric canonical quantum gravity. This is achieved by a Born-Oppenheimer type of expansion, in analogy to the case of the usual Wheeler-DeWitt equation. The formalism is only consistent if the states at each order depend on the gravitino field. We recover at consecutive orders the Hamilton-Jacobi equation, the functional Schrodinger equation, and quantum gravitational correction terms to this Schrodinger equation. In particular, the following consequences are found: (i) the Hamilton-Jacobi equation and therefore the background spacetime must involve the gravitino, (ii) a (many fingered) local time parameter has to be present on $SuperRiem \Sigma$ (the space of all possible tetrad and gravitino fields), (iii) quantum supersymmetric gravitational corrections affect the evolution of the very early universe. The physical meaning of these equations and results, in particular the similarities to and differences from the pure bosonic case, are discussed.Comment: 34 pages, clarifications added, typos correcte

Correlation Effects in Nuclear Transparency

The Glauber approximation is used to calculate the contribution of nucleon correlations in high-energy $A(e,e'N)$ reactions. When the excitation energy of the residual nucleus is small, the increase of the nuclear transparency due to correlations between the struck nucleon and the other nucleons is mostly compensated by a decrease of the transparency due to the correlations between non detected nucleons. We derive Glauber model predictions for nuclear transparency for the differential cross section when nuclear shell level excitations are measured. The role of correlations in color transparency is briefly discussed.Comment: 24 pages revtex, 4 uuencoded PostScript Figures as separate fil

Do rearing salmonids predictably occupy physical microhabitat?

Microhabitat suitability models are commonly used to estimate salmonid habitat abundance and quality with unknown accuracy or reliability. When tested, the metrics used to evaluate these models are often limited by the methods used to develop them. More generalized bioverification strategies that transcend methodology are therefore needed in ecohydraulics. This study further developed and applied such a generalized bioverification framework to four approximately 1-m-resolution rearing salmonid microhabitat suitability models. Water depth and velocity habitat suitability criteria (HSC) functions were developed for two size classes of rearing Oncorhynchus tshawytscha and O. mykiss using snorkel survey data collected over three years at seven sites along the lower Yuba River in California, USA. An expert-based cover HSC function was modified from previous studies. HSC functions were applied to previously validated, approximately 1-m-resolution two-dimensional hydrodynamic models and cover maps of the river. Mann–Whitney U tests confirmed that suitability values were significantly higher at utilized locations compared to randomly generated, non-utilized locations for all four models. Bootstrapped forage ratios demonstrated that microhabitat suitability models accurately predicted both preferred and avoided habitat beyond the 95% confidence level. This generalized bioverification framework is recommended for evaluating and comparing the accuracy and reliability of ecohydraulic models used in habitat management worldwide

Supersymmetric Quantization of Anisotropic Scalar-Tensor Cosmologies

In this paper we show that the spatially homogeneous Bianchi type I and Kantowski-Sachs cosmologies derived from the Brans-Dicke theory of gravity admit a supersymmetric extension at the quantum level. Global symmetries in the effective one-dimensional actions characterize both classical and quantum solutions. A wide family of exact wavefunctions satisfying the supersymmetric constraints are found. A connection with quantum wormholes is briefly discussed.Comment: In Press, Class. Quantum Grav. 20 pages, Late

Axially Symmetric Bianchi I Yang-Mills Cosmology as a Dynamical System

We construct the most general form of axially symmetric SU(2)-Yang-Mills fields in Bianchi cosmologies. The dynamical evolution of axially symmetric YM fields in Bianchi I model is compared with the dynamical evolution of the electromagnetic field in Bianchi I and the fully isotropic YM field in Friedmann-Robertson-Walker cosmologies. The stochastic properties of axially symmetric Bianchi I-Einstein-Yang-Mills systems are compared with those of axially symmetric YM fields in flat space. After numerical computation of Liapunov exponents in synchronous (cosmological) time, it is shown that the Bianchi I-EYM system has milder stochastic properties than the corresponding flat YM system. The Liapunov exponent is non-vanishing in conformal time.Comment: 18 pages, 6 Postscript figures, uses amsmath,amssymb,epsfig,verbatim, to appear in CQ

Exact Conformal Scalar Field Cosmologies

New exact solutions of Einstein's gravity coupled to a self-interacting conformal scalar field are derived in this work. Our approach extends a solution-generating technique originally introduced by Bekenstein for massless conformal scalar fields. Solutions are obtained for a Friedmann-Robertson-Walker geometry both for the cases of zero and non-zero curvatures, and a variety of interesting features are found. It is shown that one class of solutions tends asymptotically to a power-law inflationary behaviour $S(t)\sim t^p$ with $p>1$, while another class exhibits a late time approach to the $S(t)\sim t$ behaviour of the coasting models. Bouncing models which avoid an initial singularity are also obtained. A general discussion of the asymptotic behaviour and of the possibility of occurrence of inflation is provided.Comment: Latex, 27 pages plus 16 figures (not included, available from the authors upon request) DFFCUL-94-01-0

The (p,n) Reaction at Intermediate Energies with the Isotopes of Oxygen (16-O, 17-O, 18-O) and 9-Be as Part of a Unified Approach to the Study of These Nuclei

This work was supported by National Science Foundation Grants PHY 76-84033A01, PHY 78-22774, and Indiana Universit

The (p,n) Reaction at Intermediate Energies With the Isotopes of Oxygen (16-O, 17-O, 18-O) and 9-Be as Part of a Unified Approach to the Study of These Nuclei

This work was supported by National Science Foundation Grant PHY 76-84033 and Indiana Universit

The (p,n) Reaction at Intermediate Energies with the Isotopes of Oxygen (16-O,17-O,18-O) and 9-Be as Part of a Unified Approach to the Study of These Nuclei

Supported by the National Science Foundation and Indiana Universit