Floristic Investigations of the Ozark Plateau National Wildlife Refuge and the Genus Quercus in Oklahoma

The work presented in this thesis comprises two parts. The first part is a floristic survey of three tracts of the Ozark Plateau National Wildlife Refuge located in the Boston Mountains ecoregion in Adair County. The second part is a taxonomic treatment of the genus Quercus in Oklahoma which is to be incorporated in the forthcoming Flora of Oklahoma. Results of these studies are summarized in the following paragraphs. In a three-year (2007-2009) inventory of the Gittin Down Mountain, Liver and Varmint tracts of the Ozark Plateau National Wildlife Refuge in Adair County, Oklahoma, 392 species in 275 genera and 85 families were encountered. Three hundred sixty (91.8%) of the species were native to North America. Constituting 23.6% of the flora, the Asteraceae and Poaceae were the largest families. Quercus, Carex, Desmondium, and Dichanthelium were the largest genera present. Eighty-two species were new records for Adair County. Species designated threatened or endangered by The Endangered Species Program of the United States Fish & Wildlife Service were not discovered. Thirteen species designated rare (S1 or S2) by the Oklahoma Natural Heritage Inventory were documented as present. Herbarium and field studies conducted from 2006 to 2009 revealed that the oak (Quercus) flora of Oklahoma comprises 24 species, 3 varieties, 4 named hybrids and numerous putative hybrid individuals. Sixty-five morphological characters were examined and scored in order to generate taxon descriptions. The range of variation for each character exhibited by Oklahoma individuals was determined and incorporated in the species descriptions. Nomenclatural, taxonomic, and ecological notes were added as appropriate to complement the morphological descriptions. A dichotomous key for the identification of the 24 species and 4 named hybrids was constructed.Department of Botan

Cosmic Censorship, Area Theorem, and Self-Energy of Particles

The (zeroth-order) energy of a particle in the background of a black hole is given by Carter's integrals. However, exact calculations of a particle's {\it self-energy} (first-order corrections) are still beyond our present reach in many situations. In this paper we use Hawking's area theorem in order to derive bounds on the self-energy of a particle in the vicinity of a black hole. Furthermore, we show that self-energy corrections {\it must} be taken into account in order to guarantee the validity of Penrose cosmic censorship conjecture.Comment: 11 page

STATIONARY SOLUTIONS IN BRANS-DICKE STOCHASTIC INFLATIONARY COSMOLOGY

In Brans-Dicke theory the Universe becomes divided after inflation into many exponentially large domains with different values of the effective gravitational constant. Such a process can be described by diffusion equations for the probability of finding a certain value of the inflaton and dilaton fields in a physical volume of the Universe. For a typical chaotic inflation potential, the solutions for the probability distribution never become stationary but grow forever towards larger values of the fields. We show here that a non-minimal conformal coupling of the inflaton to the curvature scalar, as well as radiative corrections to the effective potential, may provide a dynamical cutoff and generate stationary solutions. We also analyze the possibility of large nonperturbative jumps of the fluctuating inflaton scalar field, which was recently revealed in the context of the Einstein theory. We find that in the Brans--Dicke theory the amplitude of such jumps is strongly suppressed.Comment: 19 pages, LaTe

Cosmic optical activity in the spacetime of a scalar-tensor screwed cosmic string

Measurements of radio emission from distant galaxies and quasars verify that the polarization vectors of these radiations are not randomly oriented as naturally expected. This peculiar phenomenon suggests that the spacetime intervening between the source and observer may be exhibiting some sort of optical activity, the origin of which is not known. In the present paper we provide a plausible explanation to this phenomenon by investigating the r\^ole played by a Chern-Simons-like term in the background of an ordinary or superconducting screwed cosmic string in a scalar-tensor gravity. We discuss the possibility that the excess in polarization of the light from radio-galaxies and quasars can be understood as if the electromagnetic waves emitted by these cosmic objects interact with a scalar-tensor screwed cosmic string through a Chern-Simons coupling. We use current astronomical data to constrain possible values for the coupling constant of this theory, and show that it turns out to be: $\lambda \sim 10^{-26}$ eV, which is two orders of magnitude larger than in string-inspired theories.Comment: Revised version, to appear in Phys. Rev.

A spatially-VSL gravity model with 1-PN limit of GRT

A scalar gravity model is developed according the 'geometric conventionalist' approach introduced by Poincare (Einstein 1921, Poincare 1905, Reichenbach 1957, Gruenbaum1973). In principle this approach allows an alternative interpretation and formulation of General Relativity Theory (GRT), with distinct i) physical congruence standard, and ii) gravitation dynamics according Hamilton-Lagrange mechanics, while iii) retaining empirical indistinguishability with GRT. In this scalar model the congruence standards have been expressed as gravitationally modified Lorentz Transformations (Broekaert 2002). The first type of these transformations relate quantities observed by gravitationally 'affected' (natural geometry) and 'unaffected' (coordinate geometry) observers and explicitly reveal a spatially variable speed of light (VSL). The second type shunts the unaffected perspective and relates affected observers, recovering i) the invariance of the locally observed velocity of light, and ii) the local Minkowski metric (Broekaert 2003). In the case of a static gravitation field the model retrieves the phenomenology implied by the Schwarzschild metric. The case with proper source kinematics is now described by introduction of a 'sweep velocity' field w: The model then provides a hamiltonian description for particles and photons in full accordance with the first Post-Newtonian approximation of GRT (Weinberg 1972, Will 1993).Comment: v1: 11 pages, GR17 conf. paper, Dublin 2004, v2: WEP issue solved, section on acceleration transformation added, text improved, more references, same results, v3: typos removed, footnotes, added and references updated, v4: appendix added, improved tex

Classical tests in brane gravity

The vacuum solutions in brane gravity differ from those in 4D by a number of additional terms and reduce to the familiar Schwarzschild metric at small distances. We study the possible roles that such terms may play in the precession of planetary orbits, bending of light, radar retardation and the anomaly in mean motion of test bodies. Using the available data from Solar System experiments, we determine the range of the free parameters associated with the linear term in the metric. The best results come from the anomalies in the mean motion of planets. Such studies should shed some light on the origin of dark energy via the solar system tests.Comment: 10 pages, no figures, to appear in CQ