Digital Commons Network^™

Sulfide In Surface Waters Of The Western Atlantic Ocean, Gregory A. Cutter, Christian F. Krahforst

OES Faculty Publications

Using newly developed techniques, some preliminary data on hydrogen sulfide in surface waters of the western Atlantic have been obtained. Concentrations of total sulfide range from <0.1 to 1.1 nmol/L, and vary on a diel basis. At these concentrations, sulfide may affect the cycling of several trace metals via the formation of stable complexes. Production of sulfide in oxygenated seawater may occur through the hydrolysis of carbonyl sulfide or by sulfate reduction within macroscopic particles in the water column. Removal mechanisms can include oxidation, complexation with particulate trace metals, and metal sulfide precipitation. However, the temporal and spatial distributions suggest a complex set of processes governing the behavior of sulfide in the surface ocean.

Recent Benthic Foraminifera Of Breton And Stake Islands Northern Gulf Of Mexico, Eric S. Collins

OES Theses and Dissertations

Fifty-three species of recent benthic foraminifera and thecamoebians have been documented and described from the Breton and Stake Island area, northern Gulf of Mexico, and from a core from Barataria Basin, Mississippi delta.

Cluster analysis of benthic assemblages using presence/absence and transformed abundance data reveals the presence of a marsh and shallow water marine biofacies. Based on the results of a presence/absence cluster analysis, the shallow water marine biofacies can be subdivided into a miliolid biofacies am an Ammonia beccarii/Elphidium species biofacies. Cluster analysis of transformed abundance data, however, shows that the shallow marine biofacies can be subdivided into four …

The Synthesis And Evaluation Of 5-Phenyloxazolidines As Potential Cardiovascular Drugs, Tammy C. Wang

Chemistry & Biochemistry Theses & Dissertations

Drugs such as adrenoceptor antagonists and certain centrally acting agents are known to lower blood pressure and thus serve as clinically useful antihypertensive agents. Norepinephrine 4, a natural ∝-adrenoceptor agonist, is the major agent associated with increased blood pressure in the periphery. Based on a careful structure-activity comparison, a series of substituted oxazolidines, 20, 21, 22 and 23, have been designed as possible antihypertensive candidates. Specifically, 22 and 23 have been synthesized to serve as potential norepinephrine antagonists.

Preliminary evaluation of these compounds indicated that they were not antihypertensive in nature. The more active compound, 23, …

Optimization Of The Tungstic Acid Denuder Technique For The Measurement Of Atmospheric Ammonia, Patricia Diane Roberts

Chemistry & Biochemistry Theses & Dissertations

Measurement of - atmospheric ammonia with the tungstic acid denuder technique is discussed. Characterization of denuder tubes for manual sampling in terms of, repeatability, reliability and the development of ammonia blank signals was determined. Field testing of the manual sampling apparatus was performed at ground test sites and in a biomass burn smoke plume. Ammonia emissions from biomass burning are discussed.

Nutrient Cycling In Bordenstake Bay Sediments: A Backbarrier Lagoon, Mark J. Herrenkohl

OES Theses and Dissertations

Six sets of sediment cores were collected over a one year period (June 1986 to July 1987) to examine nutrient cycling in Bordenstake Bay, a back barrier lagoon on Virginia's Eastern Shore Peninsula. The sampling times were chosen to examine any seasonal effects (e.g., temperature changes) which may affect the rates of metabolism in these sediments.

The sedimentation rate in Bordenstake Bay is 0.76 ± 0.21 cm/yr, leading to the annual deposition of 7. 05 moles of carbon, 0.46 moles of nitrogen, and 0.15 moles of phosphorus, per square meter of the sediment surface. The remineralization of organic matter in …

Structural Geology Of Page Valley, Page County, Virginia, Tamera J. Warden

OES Theses and Dissertations

Page Valley contains folded and faulted Cambro-Ordovician rocks that were deformed during the Pennsylvanian-Permian Alleghanian Orogeny. Previous authors (Allen, 1967; Thornton, 1953; and King, 1950) have mapped "high-angle" faults and a klippe along the South Fork of the Shenandoah River west of Luray, Virginia. The southernmost fault offsets the New Market/Lincolnshire and Edinburg formations with the upthrown block to the west. Thornton suggested gravity sliding and strike-slip movement to explain normal displacements along the northernmost fault where the Edinburg Formation is in contact with overturned beds of the Beekmantown Formation. A klippe, as mapped by Allen and Thornton, lies on …

Survival And Reproduction Of The Freshwater Grass Shrimp Palaemonetes Paludosus (Gibbes 1850) (Decapoda:Palaemonidae), In Saline Water, Brian Thomas Lowe

OES Theses and Dissertations

To determine the effects of salinity on adult and larval survival, egg deposition, egg hatching and metamorphosis, shrimp were held in the laboratory and exposed to treatment salinities ranging from O to 35 ppt. Tests on adult survival indicate a 96 hour LC-50 between 30 and 35 ppt. Longer term tests on adult survival showed high mortality in salinities greater than 15 ppt. Shrimp became ovigerous in salinities of O - 20 ppt with egg hatching and metamorphosis limited to O - 5 ppt. Starved- larvae hatched from field captured ovigerous females in O ppt were able to metamorphose in …

Distribution Of Suspended Particulate Matter, Patuxent River Estuary, Maryland, Christopher W. Frye

OES Theses and Dissertations

Physical processes which may affect estuarine circulation in a coastal plain estuary were monitored to determine their relative importance on temporal and spatial variability of the concentration, composition, and particle-size of suspended particulate matter (SPM) in Patuxent River estuary, MD, during 1985-86. Discharge rates from Patuxent River determined the character of fresh and estuarine water mixing, and magnitude of SPM concentration in the upper estuary. The mixing zone between fresh and estuarine water, defined as 0 - 1.5 °‰, and turbidity maximum were geographically separated during most of the study period. This suggests that two-layer circulation may be less important …

Trace Elements In Northern Virginia Middle Ordovician Carbonates: Implications For Diagenesis, Ruth Ann Strauss

OES Theses and Dissertations

Ninety-three carbonate rock samples collected from four of the major lithofacies types present in the Middle Ordovician limestone sequence of northwestern Virginia were analyzed to investigate whether the lithofacies bear the geochemical signature of the depositional and/or the diagenetic environment. Significant variations in Cr, Fe, Mg, Mn and Sr concentrations exist among the major lithofacies types. Low levels of Sr in both New Market lithofacies are indicative of an open system during diagenesis. Dissimilar Fe and Mn concentrations between these, however, reflect water chemistry differences in the depositional environment. Increasingly greater Cr, Fe, Mn, and Sr concentrations in the Lincolnshire …

The Effects Of Low Doses (1 To 500 Kilograys) Of 100-Kev Electrons On Four Polymers, Cynthia Anne Bradbury

Physics Theses & Dissertations

Commercial films of polyetherimide (PEI), polyetheretherimide (PEEI), polyethylene terephthalate (PET), and polycarbonate (PC) were exposed in vacuum to l 00-keV electron radiation to total absorbed doses of l, l 0, l 00, 300, and 500 kilograys. The concentration of radiation-generated radicals, as measured by electron paramagnetic resonance (EPR), increased by over an order of magnitude in all four polymers. Correspondingly, the intensity of the infrared absorption peaks increased uniformly for all doses. Solubility tests resulted in decreased solubility in all polymers. IR, EPR, and solubility suggest dehydrogenation of the aliphatic C-H and phenyl C-H sites. The data indicated that cross …

Theory Of Alpha-Nucleus Collisions At High Energies, Francis A. Cucinotta

Physics Theses & Dissertations

The interaction of high energy alpha particles with atomic nuclei is considered using multiple scattering theories. Semi-classical solutions to coupled-channel equations derived from Watson's form of the nucleus-nucleus multiple scattering series are shown to be equivalent to the Glauber multiple scattering series. Second-order solutions for the elastic amplitude are developed and used to study the effects of short-range correlations in nuclear scattering. The Jastrow method is used to model the two-particle density for ⁴He and to construct one and two particle form factors. Excellent agreement with experimental data for angular distributions, and total and reaction cross sections is found. …

Foraminiferal Biostratigraphy And Paleoenvironmental Analysis Of The Anahuac Formation (Late Oligocene-Early Miocene) From A Deep Well In Vermilion Parish, Louisiana, Audrey Lynne Orndorff

OES Theses and Dissertations

In the subsurface of Vermilion Parish, Louisiana, sediments from the Anahuac Formation in the #1 J. W. Steen well are assigned an Upper Oligocene-Lower Miocene age based on planktonic foraminifera. Previous age determinations for sediments from this formation elsewhere range from Middle to Late Oligocene based on the presence of larger foraminifera contained within these strata. Planktonic foraminifera in Anahuac formation sediments in the #1 J. W. Steen well permit their assignment to an established worldwide zonation scheme and indicate that the age ranges from the Globorotalia kugleri Interval Zone (Upper Oligocene) to the Catapsydrax dissimilis Zone (Lower Miocene). Benthic …

Economic Considerations For Artificial Reef Development In Coastal Virginia, Dean Thomas Devereaux

OES Theses and Dissertations

The contingent valuation method, recommended by the U. S. Water Resources Council, was used to estimate the economic value of sport fishing and diving at the Chesapeake Light Tower Artificial Reef. The study is based on a random sample of 170 anglers and 33 divers who participated in telephone, personell and mail-in surveys in 1985 and 1986.

The average user value (consumer surplus) was $21.13, $110,75, and $13.30 for head boat anglers, private boat anglers and sport divers, respectively, who claimed to have used the reef in 1985. Variation in consumer surplus was statistically affected by trip expense, distance from …

Holocene Geology And Migration Of A Low-Profile Barrier Island System, Metompkin Island, Virginia, Mark R. Byrnes

OES Theses and Dissertations

Analysis of historical shoreline position, cross-island profile change, and stratigraphic data provided a shoreline response model for low-profile barrier island systems. Historical shoreline data illustrates continuous, shore-parallel retreat between 1852 and 1957, at which time the island narrowed to a width of approximately 200 m. Between 1957 and 1981, ephemeral inlet breaching along southern Metompkin Island disrupted longshore sediment transport, increased the rate of shoreline recession, and resulted in differential rates of retreat associated with an abrupt break in backbarrier morphology. By 1981, a 400 m offset had formed at a position midway along Metompkin Island, suggesting that ephemeral inlet …

Callianassa Trilobata (Crustacea: Thalassinidea) Influences Abundance Of Meiofauna And Biomass, Composition, And Physiologic State Of Microbial Communities Within Its Burrow, Fred C. Dobbs, James B. Guckert

OES Faculty Publications

Biochemical and traditional methods were used to determine the influence of Callianassa trilobata on microbiological and meiofaunal communities within its large, highly consolidated burrow. Sediment was collected from the lining of the shrimp's burrow, the burrow matrix, and ambient, subsurface sediment. The lining and matrix were composed of poorly sorted, fine-grained material compared to sandy ambient sediment. Meiofauna, predominantly nematodes, were most abundant in ambient sediment, not in the burrow as has been found for other species of macrofauna. Concentrations of chlorophyll a were very high in the lining, consistent with the suggestion that C. trilobata lines its burrow walls …

Microbial Food Resources Of The Macrofaunal-Deposit Feeder Ptychodera Bahamensis (Hemichordata: Enteropneusta), Fred C. Dobbs, James B. Guckert

OES Faculty Publications

Biochemical and traditional analyses were used to characterize the microbial food resources and digestive efficiency of Ptychodera bahamensis, an enteropneust hemichordate. Sediment was collected from freshly extruded fecal casts and adjacent feeding depressions. There were no significant differences between casts and depressions in median grain size, percent silt-clay, density of total meiofauna and of nematodes, and concentrations of chlorophyll a and phaeophytin. Nematodes in casts had a median diameter greater than those in depressions. Measures of total, viable microbial biomass were 30% (total phospholipid, ester-linked fatty acids) and 49% (extractible phospholipid phosphate) lower in casts. Concentrations of 33 fatty …

Reactions Of Aqueous Chlorine In The Gastric Fluid Of The Rat, Michael Gary Nickelsen

Chemistry & Biochemistry Theses & Dissertations

Gastric fluid was recovered from Sprague-Dawley rats that had been fasted for 24 hr or 48 hr and administered 4 mL deionized water. The protein, carbohydrate and chloride ion content of the gastric fluid was determined.

When gastric fluid is chlorinated with radiolabeled chlorine to concentrations between 323 and 375 mg/L, analyzed by high performance chromatography followed by liquid scintillation counting, as much as 59% of the radiolabeled chlorine was associated with organic components of the gastric fluid.

Model studies with the aromatic amino acids and the protein pepsin showed the formation of chlorinated analogs. Two chlorinated amino acid derivatives …

Low Pressure Gas Flow Analysis Through An Effusive Inlet Using Mass Spectrometry, David Robert Brown

Chemistry & Biochemistry Theses & Dissertations

A mass spectrometric method for analyzing flow past and through an effusive inlet designed for use on the tethered satellite and other entering vehicles is discussed. Source stream concentrations of species in a gaseous mixture are determined using a calibration of measured mass spectral intensities versus source stream pressure for standard gas mixtures and pure gases. Concentrations are shown to be accurate within experimental error. Theoretical explanations for observed mass discrimination effects as they relate to the various flow situations in the effusive inlet and the experimental apparatus are discussed.

Use Of 52Cr For The Quantitative Determination Of Red Cell Volume, Claude Michael Hanbury

Chemistry & Biochemistry Theses & Dissertations

Chromium-52 has recently been suggested for use as a new agent to label red cells for the in vivo quantitation of red cell volume (1). In this paper, the development and validation of a routine ⁵²cr labeling procedure is described.

The accuracy, precision, and detection limits of chromium analysis by Zeeman effect atomic absorption spectroscopy was evaluated in the concentration range of 1 - 10 ug Cr/L.

Red cell chromium uptake was evaluated as a function of time, temperature, and concentration. Red cells labeled with a 2.5 mg/L chromium solution for 30 minutes at room temperature exhibited optimal label …

Evaluation Of Possible Reproductively Mediated Character Displacement In The Crayfishes, Orconectes Rusticus And O. Sanbornii, Mark J. Butler Iv

Biological Sciences Faculty Publications

Orconectes rusticus is replacing several species of crayfishes in north-central and northeastern North America, including O. sanbornii in Ohio. Recent evidence suggests that the species replacements may be driven by asymmetrical reproductive success favoring O. rusticus. Nonetheless, some sympatric associations appear locally persistent. Because crayfish demonstrate size assortative mating and there is a disparity in the sizes of the species, further divergence in the sizes of the species in sympatry could enhance reproductive isolation, ultimately providing a mechanism for character displacement. To test this hypothesis the size differentials between crayfish collected from allopatric and sympatric populations in east-central Ohio …

The Effects Of Siltation On Recruitment Of Spiny Lobsters, Panulirus Argus, William F. Herrnkind, Mark J. Butler, Richard A. Tankersley

Biological Sciences Faculty Publications

Fewer juvenile pinry lobsters were found in areas of the Florida Keys where their primary habitat was heavily silted as compared with similar, less silted habitat. Several hypotheses explaining this relationship were tested, and the time-to-metamorphosis was compared for settling pueruli within silted and nonsilted algae stands. Limited postlarval settlement and avoidance of silted algal habitats by juveniles, probably accounts for the paucity of young lobsters in heavily silted sites. In addition, although juvenile lobsters are nonselective predators, lower prey availability in silted algae probably promotes transciency which, in turn, causes increased mortality by predation while juveniles are exposed.

Variability Of Surface Pigment Concentrations In The South Atlantic Bight, Charles R. Mcclain, James A. Yoder, L. P. Atkinson, J. O. Blanton, T. N. Lee, J. J. Singer, Frank Muller-Karger

CCPO Publications

A 1‐year time sequence (November 1978 through October 1979) of surface pigment images from the South Atlantic Bight (SAB) was derived from the Nimbus 7 coastal zone color scanner. This data set is augmented with in situ observations of hydrographic parameters, freshwater discharge, sea level, coastal winds, and currents for the purpose of examining the coupling between physical processes and the spatial and temporal variability of the surface pigment fields. The SAB is divided into three regions: the east Florida shelf, the Georgia‐South Carolina shelf and the Carolina Capes. Six‐month "seasonal" mean pigment fields and time series of mean values …

No Antitwins In Minimal Imperfect Graphs, Stephan Olariu

Computer Science Faculty Publications

It is customary to call vertices x and y twins if every vertex distinct from x and y is adjacent either to both of them or to neither of them. By analogy, we shall call vertices x and yantitwins if every vertex distinct from x and y is adjacent to precisely one of them. Lovász proved that no minimal imperfect graph has twins. The purpose of this note is to prove the analogous statement for antitwins.

Consequences Of Thymidine Catabolism For Estimates Of Bacterial Production: An Example From A Coastal Marine Sediment, Kevin R. Carman, Fred C. Dobbs, James B. Guckert

OES Faculty Publications

Radioactively labeled thymidine (TdR) has been used extensively to measure bacterial production in aquatic environments, but critical assumptions of the TdR technique often have gone untested. In this study of a coastal marine sediment, the metabolic fate of methyl [³H]TdR and methyl [¹⁴C]TdR was at variance with the assumptions necessary for determining bacterial production. Only 2% of incorporated radioactivity was recovered in the DNA fraction of TCA-insoluble material following time-course incubations of l-300 min. At least the methyl group of TdR was extensively catabolized, as shown by copious production of ¹⁴C0₂. The temporal …

A Mathematical Model Of Tumor Growth By Diffusion, John A. Adam

Mathematics & Statistics Faculty Publications

A diffusion model of the prevascular stage of tumor growth is presented. The basic feature of such a model is the diffusion of growth inhibitor, which is produced at a spatially non-uniform rate within the tissue. Regimes of limited and unlimited tissue growth are determined, and the consistency of this and simpler models is discussed in the light of observational results.

The Energy-Dependence Of Polarization Observables In The ²H(D,Γ)⁴He Reaction, H. R. Weller, R. M. Whitton, J. Langenbrunner, Evans Hayward, W. R. Dodge, S. Kuhn, D. R. Tilley

Physics Faculty Publications

Measurements of the tensor and vector analyzing powers, A_yy(130°) and A_y(130°), have been obtained for the ²H(d,γ )⁴He reaction for energies ranging from E_d(lab) = 0.3 MeV to E_d(lab) = _{50 MeV}. The A_yy(130°) data are sensitive to the D-state present in the ground state of ⁴He and are observed to have their maximum value near E_d = 30 MeV. The vector analyzing power data show a maximum near E_d = 3 MeV. The data are compared to the results of a microscopic …

Uniform L1 Behavior In Classes Of Integrodifferential Equations With Convex Kernels, Richard Noren

Mathematics & Statistics Faculty Publications

No abstract provided.

An Optically Controlled Closing And Opening Semiconductor Switch, K. H. Schoenbach, V. K. Lakdawala, R. Germer, S. T. Ko

Electrical & Computer Engineering Faculty Publications

A concept for a bulk semiconductor switch is presented, where the conductivity is increased and reduced, respectively, through illumination with light of different wavelengths. The increase in conductivity is accomplished by electron ionization from deep centers and generation of bound holes. The reduction of conductivity is obtained by hole ionization from the excited centers and subsequent recombination of free electrons and holes. The transient behavior of electron and hole density in a high power semiconductor (GaAs:Cu) switch is computed by means of a rate equation model. Changes in conductivity by five orders of magnitude can be obtained.

A Mathematical Model Of The Dynamics Of An Optically Pumped Four-Level Solid State Laser System, Lila Freeman Roberts

Mathematics & Statistics Theses & Dissertations

This is a study of a mathematical model of the dynamics of an optically pumped four-level solid state laser system. A general mathematical model that describes the spatial and temporal evolution of the electron populations in the laser rod as well as the development of the left and right traveling photon fluxes in the cavity is developed. The model consists of a coupled set of first order semilinear partial differential equations. While the model was developed for Titanium-doped sapphire lasers, it is applicable to three and four level lasers in general.

The analysis of the model is conducted in two …