Digital Commons Network^™

Is Growth Of Eelgrass Nitrogen Limited? A Numerical Simulation Of The Effects Of Light And Nitrogen On The Growth Dynamics Of Zostera Marina, Richard C. Zimmerman, Robert D. Smith, Randall S. Alberte

OES Faculty Publications

A numerical model of nitrogen uptake and growth was developed for the temperate seagrass Zostera marina L. Goals were to evaluate the relative effects of light and nitrogen availability on nitrogen uptake and partitioning between leaf and root tissue, and to estimate nitrogen concentrations in the sedment and water column required to saturate growth. Steady-state predictions are quite robust with respect to a range of parameter values justified by available data The calculations indicated that roots are probably more important in overall nitrogen acquisition in most light and nitrogen environments encountered in situ, but may contribute less than 50 …

Acceleration Of Nutrient Uptake By Phytoplankton In A Coastal Upwelling Ecosystem: A Modeling Analysis, Richard C. Zimmerman, James N. Kremer, Richard C. Dugdale

OES Faculty Publications

Studies of upwelling centers in the eastern Pacific suggest that maximum rates of nitrate uptake (light and nutrient saturated) increase, or shift-up, as newly upwelled water moves downstream. The rate of shift-up appears to be related to irradiance and the ambient concentration of limiting nutrient at the time of upwelling. A mathematical model was developed to evaluate effects of irradiance and initial nitrate concentration on temporal patterns of shift-up and subsequent time scales of nutrient utilization over a range of simulated upwelling conditions. When rates consistent with field studies were used, complete shift-up was possible only under certain conditions, and …

Coupled Bending-Torsion Steady-State Response Of Pretwisted, Nonuniform Rotating Beams Using A Transfer-Matrix Method, Carl E. Gray Jr.

Mechanical & Aerospace Engineering Theses & Dissertations

Using the Newtonian method, the equations of motion are developed for the coupled bending-torsion steady-state response of beams rotating at constant angular velocity in a fixed plane. The resulting equations are valid to first order strain-displacement relationships for a long beam with all other nonlinear terms retained. In addition, the equations are valid for beams with the mass centroidal axis offset (eccentric) from the elastic axis, nonuniform mass and section properties, and variable twist. The solution of these coupled, nonlinear, nonhomogeneous, differential equations is obtained by modifying a Hunter linear second-order transfer-matrix solution procedure to solve the nonlinear differential equations …

Depositional And Diagenetic History Of The Middle Ordovician Carbonates Of The Shenandoah Valley, Northern Virginia, Lynn Ellen Weyenberg

OES Theses and Dissertations

An examination of the Middle Ordovician carbonates in northwest Virginia has revealed a particularly sensitive record of deposition and subsidence. Two-hundred acetate peels from six measured stratigraphic sections in Shenandoah County, Virginia were examined to interpret the depositional and diagenetic history. Two major lithofacies have been recognized within the New Market Limestone and three have been recognized in the Lincolnshire Formation. These five lithofacies represent an overall transgressive sequence. This transgression was not uniform but paused several times to allow carbonate deposition to reach sea-level. These shoaling events suggest a slowly subsiding basin in this region. The carbonate rocks within …

The Hydrogeology Of Nags Head Woods, Dare County, North Carolina, Janet Salyer Emry

OES Theses and Dissertations

Nags Head Woods, a coastal maritime forest located on a barrier island in eastern North Carolina, stabilizes a back-barrier dune system bordering a tidal marsh. The purpose of this study is to provide basic information about the groundwater geology in Nags Head Woods and to predict the effects upon water levels due to municipal pumping of Fresh Pond, a large lake near the center of the island.

Clean, fine-to-medium sands dominate the top of the surficial (water table) aquifer, underlain by silty fine-to-coarse sands at -4 m elevation. A silty clay bed of very low permeability is present at -12 …

On The Thermal Stresses Due To A Uniform Heat Flow Past A Circular Hole With A Radial Edge Crack, George F. Edmonds

Mathematics & Statistics Theses & Dissertations

The problem solved in this dissertation is that of finding the stresses in an isotropic, linear, thermoelastic solid when a uniform heat flow is disturbed by the presence of an insulated circular hole with a radial edge crack. By superimposing a Mellin transform solution of the equations of thermoelasticity on a Michell series solution the author reduces the problem to a pair of singular integral equations which are then solved numerically. The stress intensity factors and crack formation energies, quantities of interest to workers in fracture mechanics, are then calculated.

A Criterion For Vortex Breakdown, R. E. Spall, T. B. Gatski, C. E. Grosch

CCPO Publications

A criterion for the onset of vortex breakdown over a wide range of the Reynolds number is proposed. Based upon previous experimental, theoretical, and numerical studies, as well as a new numerical study, an appropriately defined local Rossby number is used to delineate the region where breakdown occurs. Comparisons are made with previously suggested criticality parameters and the unique features of the proposed Rossby number parameter are shown. A number of previous theoretical studies concentrating on inviscid standing‐wave analyses for trailing wing‐tip vortices are reviewed and reinterpreted, along with the previous numerical and experimental studies, in terms of the Rossby …

Fracture Detection In A Volcanic Oil Reservoir Using Discriminant Analysis Of Well Log Data, Joseph William Cross

OES Theses and Dissertations

A new method of detecting fractures using well logs is presented. The technique uses discriminant analysis to distinguish fractured from unfractured reservoir rock and was developed for the volcanic pay zone of Jatibarang oilfield, West Java, Indonesia.

The a priori information required to derive the discriminant function was provided by 22 wells known to penetrate intervals of either fractured or unfractured volcanics. The samples consisted of these 22 intervals digitized in one-meter increments (1256 meters total thickness). The discriminating variables were the petrophysical measurements made by 10 different types of well logs.

Discriminant analysis correctly classified 94.2% of the total …

Mesoscale Hydrographic Variability In The Vicinity Of Points Conception And Arguello During April May 1983: The Opus 1983 Experiment, Larry P. Atkinson, Kenneth H. Brink, Russ E. Davis, Burton H. Jones, Theresa Paluszkiewicz, David W. Stuart

CCPO Publications

In April and May 1983, interdisciplinary oceanographic observations were made of upwelling events in the Point Conception area off southern California. The principal objective was to observe the structure and time dependence of the upwelling system. To accomplish this, two ships, two aircraft, moorings, drogues, and satellite imagery were all included in the observational effort. During the intensive measurement period three main upwelling events and two intervening relaxation or downwelling intervals were sampled during what was a period of overall longer-term sea surface warming. Surface temperatures during upwelling were as low as 10.5°C in the upwelling center between Point Arguello …

Experimental Fine-Structure Branching Ratios For Na-Rare-Gas Optical Collisions, Mark D. Havey, F. T. Delahanty, Linda L. Vahala, Gary E. Copeland

Electrical & Computer Engineering Faculty Publications

Experimental ratios for branching into the fine-structure levels of the Na 3p multiplet, as a consequence of an optical collision with He, Ne, Ar, Kr, or Xe, are reported. The process studied is Na(3s²S_1/2)+R+nhNNa(3^p2P_j)+R+(n-1)_hN, where R represents a rare-gas atom and where the laser frequency N is tuned in the wings of the Na resonance transitions. The branching ratios are defined as I(D1)/I(D2) where I(D1) and I(D2) are measured intensities of the atomic Na D1 and D2 lines. The ratios are determined for detunings ranging from about 650 …

Calibration Of Old Dominion University Low-Speed Wind Tunnel, Nicolaos P. Sargianos

Mechanical & Aerospace Engineering Theses & Dissertations

No Abstract.

The Synthesis And Evaluation Of The Cardiovascular Activity Of Novel Imidazole Ring Systems, Joseph E. De Los Angeles

Chemistry & Biochemistry Theses & Dissertations

An investigation was undertaken to synthesize and evaluate the cardiovascular activity of two imidazole ring systems. Imidazoles with hypotensive activity would provide novel potential antihypertensive drugs. These novel structures may also find use as chemical probes in the study of the cardiovascular system and as prototypes for other potential cardiovascular agents.

The histamine derivative, 7,7-dipyridyl-4,5,6,7-tetrahydroimidazo-[4,5-c]pyridine (ligand l), was demonstrated to possess significant hypotensive activity in laboratory rats. A 15 mg/Kg dose of ligand 1 produces a statistically significant decrease in blood pressure when injected IP. This hypotensive effect is also associated with marked increase in heart rate. Although compound 1 …

An Investigation Of Overvoltage Effects On A Gas-Blown Spark Gap, Michael Steven Mazzola

Electrical & Computer Engineering Theses & Dissertations

This experimental investigation addresses the anomalous overvoltage breakdown and subsequent recovery characteristics observed in gas-blown spark gaps. Previous investigations have reported a two-stage recovery process in self-break, pulse-charged, gas-blown spark gape in which the spark gap recovers first to an intermediate breakdown strength before recovering to the undisturbed breakdown voltage. The recovery process has been explained in terms of two different characteristic times. The first is that required to obtain initial recovery in which the spark gap regains its intrinsic breakdown strength. The second time is that required to obtain final recovery in which the pulse-charged spark gap regains the …

Wind Streamline Ambiguity Removal Of Microwave Scatterometer Data, Hans W. Zaepfel

Electrical & Computer Engineering Theses & Dissertations

There is a class of satellite microwave scatterometers that return oceanographic information which includes wind vectors with directional ambiguity. The first part of the ambiguity removal process is to reduce the data to a directional ambiguity of 180°. This thesis shows that wind direction change contains the information required for streamline ambiguity removal and that syntactic pattern recognition techniques can be used to locate the areas of wind direction change. Spreading the information along the areas of wind direction change results in the removal of the streamline ambiguity. The algorithm is implemented and the results are presented showing that it …

Optimal Cure Cycle Design Of A Resin-Fiber Composite Laminate, Jeenson Sheen

Mechanical & Aerospace Engineering Theses & Dissertations

High performance polymeric composites have been experiencing increasing usage in the aerospace and automobile industries. Such materials are commonly composed of long or chopped fibers embedded in the thermosetting resin matrix. Changes in physical and chemical properties of such composite materials during the cure process are rather complex. Thus, it is not a trivial task to properly design a cure cycle (temperature and pressure profiles) for a cure process. The material should be cured uniformly and completely with the lowest void content; the temperature inside the laminate must not exceed some maximum value; and the cure process should be completed …

Environmental Factors Affecting Nocturnal Migrations Of Macrobenthos, C. Timothy Morris

Biological Sciences Theses & Dissertations

Nocturnally dispersing macrobenthic invertebrates of the Lafayette River, Norfolk, Virginia were collected from September 4 to October 4, 1982 to determine environmental factors affecting migrations. A total of 55 taxa were identified from 325 surface and bottom nocturnal plankton tows. Peracaridan crustaceans were the dominant (99.0% of the total density) group collected. Six of the commonly collected species showed a significant (P

A Quantitative Approach To Simulation And Analysis Of Storm Water Systems, John Nathan Paine

Civil & Environmental Engineering Theses & Dissertations

A generalized package of hydrologic and hydraulic models and programs is developed for the quantitative analysis of watersheds and drainage networks. The package is microcomputer based and is available to interested parties. Full documentation is included in the Appendix. The approach applies a lengthy historical rainfall record to the system in continuous simulation. One of the most powerful operational hydraulic routing models available is adopted into the package. Output takes the form of statistical predictions of flood stages, discharges, storage requirements, and rainfall analyses for various return-periods. Computer runs are completely summarized. The package was applied to a 969-acre watershed …

A Histological Investigation Of The Larval Mandibular Organ In The Mud Crab Rhithropanopeus Harrisii (Gould) (Crustacea Decapoda Xanthidae), Lore Lynn Hantske

OES Theses and Dissertations

Mandibular organs of the mud crab, Rhithropanopeus harrisii (Gould) were histologically located and followed throughout the larval cycle to determine their role in metamorphosis. Specimens from each day of the four larval stages and the megalopa stage were embedded in paraffin, sectioned at 8 μm, stained and observed under the microscope for the mandibular organs. The organs were located in the mandibular area of second, third and fourth stage larvae. The organs were probably present in the first stage zoeae and in the megalopa stage, although the

techniques of the study were not sensitive enough to observe them. The …

An Experimental And Analytical Investigation Of Incompressible Fluid Flow Through A Distensible Tube System, Steven C. Wells

Mechanical & Aerospace Engineering Theses & Dissertations

An analysis was made of pressure and flow in a novel elastic tube system which has been used to theorize certain aspects of renal hemodynamic cs. Validation of the theory could alter the treatment of certain heart and kidney disorders. In an attempt to better understand a system flow anomaly under steady driving head conditions, experiments were performed, and a mathematical model was developed. The development of the model incorporated a set of nonlinear differential and algebraic equations. Using a finite-difference analysis as the method for obtaining a numerical solution, various pressures and flows were obtained. Results for the steady-state …

The Development Of A Paper-And-Pencil Measure Of Complex Cognitive-Perceptual Aptitude, Don Michael Mcanulty

Psychology Theses & Dissertations

The primary purpose of the present research was a develop a complex aptitude test to assess individual differences in multiple cognitive and perceptual abilities that are required for helicopter pilot training. The paper-and-pencil test was designed to provide measures of both static and dynamic (i.e., learning) ability under different levels of complexity. The secondary research purpose was to develop a battery of eight psychometric tests to assess other abilities that are required for helicopter pilot training. Test prototypes were produced and administered to small samples of subjects. The tests were then revised into an experimental battery that required approximately 7 …

Benthic Foraminifera And Paleoenvironments Of The Arcola Limestone Member Mooreville Formation (Campanian) In Eastern Mississippi And Western Alabama, Julia K. Palmer

OES Theses and Dissertations

Eighty-one species of benthic foraminifera have been recovered from chalky marls of the upper Mooreville Formation including the Arcola Limestone Member, and the basal Demopolis Formation located in five sections in east-central Mississippi and west-central Alabama. These species have been described and seventy-nine illustrated. Analysis of the environmental or depth preferences of abundant species together with planktonic percentages and benthic species diversity, indicates that the chalky marls were deposited in a broad shallow shelf sea (subtidal conditions less than 100m) greatly influenced by open ocean conditions. The benthic assemblage is composed of a mixture of typically neritic and bathyal species …

Geometric Photoisomer Investigation Of Bilirubin (Z,Z)-Ixα, Robert Howe Walker Iii

Chemistry & Biochemistry Theses & Dissertations

Numerous investigations of bilirubin have been reported in the literature. Correlation among these investigations can not be made because of multiple behavioral changes characteristic of the solubilized pigment. This research was initiated to evaluate bilirubin and its associated isomers in identical chemical environments.

Two different solvent systems were experimentally selected to study chemical behavior of bilirubin and occurring photoisomers. A ternary solution consisting of 1:3:1 chloroform:methanol:water was used exclusively in visible spectrophotometric analyses. Also, a pH 10.00 buffer was utilized. This latter system has successfully been used in spectrophotometric and voltammetric work.

Four different photochemical processes have been detected spectrophotometrically, …

The Effect Of Grinding On The Sorption Capacity Of Activated Carbon, John Garrett Dempsey

Civil & Environmental Engineering Theses & Dissertations

The current procedure employed to design full scale activated carbon contacting systems is presented in detail and followed by a review of the more important process controls and operating parameters. Inherent limitations of the design procedure are identified, with the need to be able to accurately predict carbon sorption capacity from bench scale analysis determined to be the most important. Some of the more recent models developed to predict activated carbon sorption capacity were analyzed leading to the realization that even the most sophisticated dynamic models were based upon sorption capacities determined from classical isotherm procedures. The validity of the …

Cognitive Influences On Flavor Discrimination: Training Novices For Beer Flavor Differentiation, Rosalynn M. Peron

Psychology Theses & Dissertations

Four training techniques were employed to investigate the effects of increasing knowledge of beer flavor on novices' ability to differentiate among beers on the basis of taste. These techniques included (a) learning definitions of beer flavor terminology (Verbal Condition); (b) having additional experience with taste sensations (Taste Condition); (c) having a combination of the verbal and taste techniques (Verbal/Taste Condition); and (d) no training (Control Condition). After preliminary testing, 40 subjects (10 per training condition) were selected to participate in pre- and post-training tasks in which they rated similarity between beers, between beers and flavor-descriptive adjectives, and between flavor-descriptive adjectives. …

Mössbauer Spectroscopic Studies Of Hemoglobin And Its Isolated Subunits, G. R. Hoy, D. C. Cook, R. L. Berger, F. K. Friedman

Physics Faculty Publications

Samples of 90% enriched ⁵⁷Fe hemoglobin and its isolated subunits have been prepared. Mössbauer spectroscopic measurements have been made on three such samples. Sample one contained contributions of oxyhemoglobin, deoxyhemoglobin, and carbonmonoxyhemoglobin. This sample was studied from a temperature of 90 K down to 230 mK. Measurements were also made at 4.2 K using a small applied magnetic field of 1.0 T. In general, the measured quadrupole splittings and isomer shifts for each component agreed with previous measurements on single component samples in the literature, and thus demonstrated that chemically enriched hemoglobin has not been altered. The second and …

Generic Specifications In Lil And In Ada Via Analogies, George Chester Harrison

Computer Science Theses & Dissertations

We address the problem of .making verifiable specifications in generic program units in the Ada Programming Language*. We illustrate the methodologies of LIL proposed by Joseph Goguen and Justify the use of such a specification languages using analogy programming originally proposed by Nachum Dershowitz. The work in these areas is new and noticeably incomplete. We address our concern about the reusability of Ada software in a programming environment that includes a specification language like LIL. * Ada is a registered trademark of the U.S. Government (Ada Joint Program Office)

Walk Naked In The Garden, Gale Coffin Arnoux

English Theses & Dissertations

Writing is an act of survival for the person who must live an examined life. The process of writing is surrounded with such private ritual as laying claim to a quiet niche in the house that will become one's place for writing, and with reading from sources deeply significant to the writer before beginning with one's own writing. Only then is the writer ready to look out at the world from his or her study window, or as Flaubert preferred, from the landscape of a wall to create a new landscape.

The landscape of most of my poems in this …

Patterns Of Diurnal Vertical Distribution And Dispersal-Recruitment Mechanisms Of Decapod Crustacean Larvae And Postlarvae In The Chesapeake Bay, Virginia And Adjacent Offshore Waters, Robert Copeland Maris

OES Theses and Dissertations

Larval dispersal and subsequent postlarval recruitment are extremely significant processes affecting the maintenance of ecologically and economically important populations of decapod crustaceans. Vertical positioning in the water column plays a major role in the particular strategies of retention or expulsion with immigration.

The present study was undertaken to investigate variations in vertical distribution according to temporal (diurnal), spatial (estuarine, transition, oceanic), ontogenetic (larval stages, postlarvae) and various environmental factors (especially light, temperature, salinity and tides). Also, effects of vertical positioning on dispersal-recruitment were examined.

Three stations were established for the present study: York River mouth (estuarine) (37°12'N, 76°16'W); Chesapeake Bay …

Disease Incidence Of Demersal Finfishes From The Southern And Western Branches Of The Elizabeth River, Virginia, Randal D. Owen

Biological Sciences Theses & Dissertations

Fishes from the industrialized environs of the Elizabeth River, Virginia were surveyed for external evidence of disease during June through October 1984. A highly significant (p < 0.001) incidence of disease was found in demersal fishes collected by otter trawl from a site in the industrially contaminated Southern Branch compared to a less contaminated Western Branch site. Cataracts, fin erosion and dermal lesions were the most commonly occurring anomalies in the Southern Branch finfish.

Static, solid-phase toxicity tests employing sediment collected from the Southern Branch site resulted in an immediate toxic stress in the spot, Leiostomus xanthurus, which resulted in 100% mortality within 24 hours, compared with no mortalities in control systems. Spot exposed to control, i.e., pollution free, and diluted Southern Branch sediments innoculated with the pathogenic bacterial species, Vibrio anguillarium, developed significant (p ≤ 0.020) cases of fin erosion at a mean total bacterial community density …

Organic Matter Budgets And Models For Four Plant Communities In The Great Dismal Swamp, J. Patrick Megonigal

Biological Sciences Theses & Dissertations

Budgets and models of organic matter dynamics were developed for one mesic and three seasonally flooded plant communities in the Dismal Swamp. Components included aboveground parts, belowground parts, litter and soil organic matter (SOM).

Net primary- production was significantly greater on them flooded sites. Comparisons show that the Dismal Swamp is highly productive despite relatively low nutrient inputs.

Budget calculations showed that over 65% of the total input to SOM comes from roots. Leaves contributed about 70% of the aboveground inputs.

The model predicted that species composition, aboveground biomass and turnover rates on the cedar site will become quite similar …