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The Aquatic Geochemistry Of The Particle-Reactive Radionuclides Po-210, Pb-210, And Be-7, James Forrest Todd

OES Theses and Dissertations

Integrated monthly wet-only and bulk precipitation samples for Be-7 and Pb-210 analysis were collected from November 1982 through October 1983 at two sites in lower Chesapeake Bay. Atmospheric deposition fluxes for Be-7 in wet-only and bulk precipitation averaged 0.013 and 0.014 pCi/cm²/d, respectively, and for Pb-210 averaged 0.36 and 0.40 pCi/cm²/yr, respectively, suggesting that dry deposition makes only a minor contribution to the total fluxes.

A seasonal trend was observed in the depositional flux of Be-7, with a pronounced maximum in the Spring. Approximately 40 percent of the annual Be-7 deposition occurred between February and April, …

A Theoretical Model For Calculation Of Molecular Stopping Power, Yuan-Jian Xu

Physics Theses & Dissertations

A modified local plasma model based on the work of Linhard-Winther, Bethe, Brown, and Walske is established. The Gordon-Kim's molecular charged density model is employed to obtain a formula to evaluate the stopping power of many useful molecular systems. The stopping power of H₂ and He gas was calculated for incident proton energy ranging from 100 KeV to 2.5 MeV. The stopping power of O₂, N₂ and water vapor was also calculated for incident proton energy ranging from 40 keV to 2.5 MeV. Good agreement with experimental data was obtained.

A discussion of molecular effects leading …

Phytoplankton Ecology And Dynamics In The James River Estuary Virginia, U. S. A., Margaret J. Filardo

OES Theses and Dissertations

Autotrophic biomass and productivity as well as nutrient distributions and phytoplankton cell populations in the James River estuary, Virginia, from Newport News Shipyard to the 0 o/oo isohaline, were sampled on a monthly basis from August of 1981 to December of 1982. Particular emphasis was placed on the very low salinity region (defined as the location where surface salinity measured between 0.0 and 0.75 o/oo based on conductivity) in order to determine the fate of fresh water phytoplankters upon being advected into the estuary because of their suspected role in the biogeochemical cycling that occurs there.

Both chlorophyll a and …

Finite Element Thermal-Structural Analysis Of Cable-Stiffened Space Structures, Ajay Kumar Pandey

Mechanical & Aerospace Engineering Theses & Dissertations

Finite element thermal-structural analyses of cable-stiffened space structures are presented. A computational scheme for calculation of prestresses in the cable-stiffened structures is also described. The determination of thermal loads on orbiting space structures due to environmental heating is described briefly. Three finite element structural analysis techniques are presented for the analysis of prestressed structures. Linear, stress stiffening and large displacement analysis techniques are investigated.

The three techniques are employed for structural analysis of prestressed cable structures at different prestress levels. The three analyses produce similar results at small prestress. but at higher prestress differences between the results become significant. For …

The Development Of A Microprocessor Controlled Linearly Actuated Valve Assembly, Raymond H. Wall

Mechanical & Aerospace Engineering Theses & Dissertations

The development of a proportional fluid control valve/assembly is presented. This electro-mechanical system is needed for space applications to replace the current proportional flow controllers that use bulky hydraulic or pneumatic actuation systems. The flow is controlled by a microprocessor system that monitors the control parameters of upstream pressure and requested volumetric flow rate. The microprocessor achieves the ·proper valve stem displacement by means of a digital linear actuator. A linear displacement sensor is used to measure the valve stem position. 'Ibis displacement is monitored by the microprocessor system as a feedback signal to close the control loop. With an …

Trait Anxiety In Female Heads Of Household, Bonnie Martinette Wheeler

Ellmer School of Nursing Theses & Dissertations

The purpose of this investigation was to determine if being the female head of a single-parent household was associated with increased trait anxiety. Ninety-four female nurses completed the Trait portion of the State-Trait Anxiety Inventory developed by Spielberger, Gorsuch, and Lushene (1964) and a demographic inventory. The demographic inventory provided the information regarding marital status and presence or absence of children needed to delineate the sample into four groups: Group I (n=31) married females with dependent children in the home; Group II (n=10) married females with no dependent children in the home; Group III (n=26) single, separated or divorced females …

Predictors Of Appointment-Keeping Behaviors Among Users Of Adult Medical Clinics, Ruth L. Campau

Ellmer School of Nursing Theses & Dissertations

In a descriptive correlational study, three predictors of appointment keeping behaviors of adults who attend general medical clinics in a primary health care setting were explored. The three selected predictors from the Health Belief Model, a preventive health behavior model, were: (a) perceived barriers to health care, (b) health locus of control (HLC), and (c) satisfaction with health care. The purpose of this study was to identify the predictive value of multiple variables for a specific health-related behavior. Data on the study were collected on a non-probability, purposive sample of 52 users of the adult general medical clinics. The tool …

Partial Radiative Recombination Cross Sections For Excited States Of Hydrogen, Patricia M. Fazio

Physics Theses & Dissertations

In calculating the radiative recombination cross sections for interstellar H II regions usually only the electric dipole term in the expansion of the interaction Hamiltonian is kept. However, conditions present in these regions permit recombination into highly excited states and the "effective size" of the atom is not much less than the wavelength of the emitted photon. These physical conditions do not meet the requirements for making the dipole approximation. A higher order approximation is to keep an additional term in the expansion of the Hamiltonian, and, therefore, to include contributions of quadrupole transitions in the calculation of the partial …

An Examination Of The Variability Of Migratory Timing Statistics Estimated From Catch And Effort Observations, Arthur J. Butt

OES Theses and Dissertations

The estimate of the mean arrival time based on catch or CPUE of fishes migrating into a fixed harvest area is a function of the number of days fished. Simulation studies using chinook salmon catch and effort data from the Yukon River delta, Alaska indicate that fishing effort concentrated at the tails of the migratory distribution which would tend to erroneously weigh the estimated mean arrival time in the direction of the sample, away from the true mean, is only a significant problem when the number of days open to fishing is small, covering less than 12% of the total …

Design Of Multivariable Feedback Control Systems Via Spectral Assignment Using Reduced-Order Models And Reduced-Order Observers, Preston Ivanhoe Carraway Iii

Electrical & Computer Engineering Theses & Dissertations

The feasibility of using reduced-order models and reduced-order observers with eigenvalue/eigenvector assignment procedures is investigated. A review of spectral assignment synthesis procedures is presented. Then, a reduced-order model which retains essential system characteristics is formulated. A constant state feedback matrix which assigns desired closed loop eigenvalues and approximates specified closed loop eigenvectors is calculated for the reduced-order model. It is shown that the eigenvalue and eigenvector assignments made in the reduced order system are retained when the feedback matrix is implemented about the full order system. In addition, those modes and associated eigenvectors which are not included in the reduced-order …

The Shenandoah National Park: Its Impact On A Mountain People, Scott Shelton

History Theses & Dissertations

The creation of the Shenandoah National Park in Virginia during the 193Os profoundly affected the lives of hundreds of mountain people who had eked out an existence to the region for generations. While removing these people naturally caused inconveniences and disrupted a way of life, the positive results outweighed the negative. Higher standards of living generally accompanied the change, and few former residents expressed discontent over their new way of life.

This removal of the mountaineers was simply one of many episodes in American history where the federal government has played a role in moving people, thereby changing their lifestyle. …

A Plasma Focus Interrupting Switch, Gregory Francis Knapp

Electrical & Computer Engineering Theses & Dissertations

The feasibility of using a dense plasma focus (DPF) as a current interrupting device has been investigated. Specifically, a 34-kJ, Mather-type DPF was modified to accept a third electrode so that a discharge could be created between this electrode and the center electrode of the DPF by a 10-kJ inductive energy storage circuit. It was anticipated that the accelerating mechanisms of the DPF pinch, which are known to cause a rapid reduction in the DPF current, would interrupt the 1-kA to 10-kA secondary discharge current thus forcing the secondary current through an external load and hence result in power amplification. …

A Description And Analysis Of The Timing Of Virginia's Weakfish Fishery, Bruce William Hill

OES Theses and Dissertations

The seasonality of Virginia's weakfish fishery is quantitatively defined by providing a mean time of catch and variance of catch for the years 1960 - 1981. On the average. the central half of the population is available for harvest from mid-May through September in all of Virginia's waters and the mean date of harvest is July 20th • The 22 year average variance of catch for Virginia's waters is 3.97. In Virginia's Chesapeake Bay tributaries the mean date of harvest is July 17th and the 22 year average variance of catch is 2.50. There is evidence for an inverse relationship …

An Investigation Of Refractive Index Of Solutions Of Ammonia And Water At Various Concentrations And Temperatures, Effendy Arif

Mechanical & Aerospace Engineering Theses & Dissertations

Refractive index of ammonia-water solutions is investigated experimentally (for (lamda) = 632.8 nm) and semi-empirically (for (lamda) = 589.3 and 632.8 nm) in ammonia-weight concentration of up to 30%, over a temperature range of 20 to 60(DEGREES)C. The experiment employs a specially designed and built refractometer that measures the displacement of a laser beam due to refraction in the test solution. The refractive index is then deduced from the beam displacement. Based on the experimental data, the refractive index is correlated empirically with the concentration and temperature. A semi-empirical investigation is developed based on the Lorentz-Lorenz equation and the additive …

An Intraseason Forecasting System For Commercial Marine Fisheries, Erik J. Barth

OES Theses and Dissertations

The reliability of an intraseason yield estimation technique which is commonly used by Pacific salmon harvest managers is evaluated for applicability to a variety of commercial finfish and crustacean fisheries. The estimation technique is known as the average timing or the average performance model. The method is not easily related to standard statistical models, but does show some similarity to both a single parameter linear regression model and the ratio estimator of sampling theory. A comparison of these models, a two parameter linear model, and a regression estimator is made to determine if the precision of forecasts of performance can …

Analysis Of Central Equatorial Pacific Water Masses By Method Of Principal Components, Ross Tuxhorn

OES Theses and Dissertations

The distribution of Antarctic Intermediate Water at the extent of dispersion in the equatorial Pacific Ocean was investigated by means of multivariate analysis. Interrelationships among the upper intermediate water masses at this location are proposed.

Oceanographic data contained in seven cruise legs measured during the 1979-80 Hawaii to Tahiti Shuttle Experiment formed the basis of this study. Six parameters -- temperature, salinity, dissolved oxygen, phosphate, silicate and nitrate -- were used in the method of principal component analysis to classify water masses between the sea surface and 1000m. The derived water masses were compatible with previously described oceanographic features of …

Investigation Of Matrix Effects On The Furnace Atomic Absorption Signals Of Chromium, Nickel And Selenium, Susan Marie Viet

Chemistry & Biochemistry Theses & Dissertations

The flameless atomic absorption signals of chromium, nickel and selenium are subject to matrix interferences arising from inorganic salts and anions commonly found in urine. The effects of such salts on the atomic absorption signals were investigated using Polarized Zeeman Effect background correction in conjunction with a detector/readout system capable of resolving absorbance signals in 18 msec readings. Both optical temperature control and current temperature control were employed for each analysis. Peak area, peak height, peak shape and appearance time were compared for matrix-free standards and matrix-containing standards.

The influence of the inorganic salts on the metal analyses was found …

A Method For Determining Creosote Contamination Of Sediment From The Elizabeth River, Norfolk, Va, Elizabeth G. Merrill

OES Theses and Dissertations

Hydrocarbon input sources to the Elizabeth River were investigated. Carbonized coal products (creosote, coal tar, and roof tar), petroleum products (Kuwait Crude Oil, No. 2 Fuel Oil, and a fuel oil spill sample) and soot (woodstove and diesel engine) have unique hydrocarbon distributions. Elizabeth River sediment hydrocarbon distributions indicate that they are contaminated with both carbonized coal and petroleum products. Using a simple two member mixing model, greater than 65 percent of Elizabeth River sediments' resolved aromatic compounds were determined to originate from carbonized coal products. These aromatic hydrocarbons include the EPA priority pollutant polynuclear aromatic hydrocarbons which are known …

Facilitating And Hindering Factors In Implementing Managerial Technology: A Socio-Technical System Process, Eduardo Alejandro Salas Garcia

Psychology Theses & Dissertations

In recent years scientists, researchers and practitioners have focused on the application and theory of managerial technologies in developing countries. Evidence suggests that the implementation of these technologies is widely sought in these countries, but that they suffer from several limitations. Among these are: (a) lack of environmental compatibility in the societies and cultures in which attempts are made to apply such organizational theories and practices; (b) differences between economic systems of developing nations and industrialized nations (c) differences in political history, values and practices and (d) differences in organizational functioning and behavior as a result of these three conditions. …

Block Transform Coding Of Presample Filtered Data, Thomas A. Shull

Electrical & Computer Engineering Theses & Dissertations

This dissertation addresses the application of non-adaptive transform coding for bit rate reduction of presampled filtered data. Transform coding is examined as an alternative to conventional pulse code modulation (PCM) for multi-source, fixed rate data acquisition systems. Typical bandlimiting presample filters introduce redundancy into the sequence of data samples. Linear transformation of successive N-length blocks of the data sequence and subsequent binary coding of the resulting components is shown to lead to reduced average bit rate for the same less distortion as PCM.

Four Butterworth filters, two corresponding to eight bit PCM systems, and two corresponding to ten bit PCM …

Staff Nurses' Self-Esteem As It Relates To Working In Specialty Areas, Donna Lynn Evans

Ellmer School of Nursing Theses & Dissertations

This study compared the levels of self-esteem of hospital staff nurses working in specialty areas versus those working in general medical-surgical areas. Fifty registered nurses employed full-time in staff positions at a large, acute-care hospital participated in the study. After indicating the area of the hospital in which they worked, the type of education they had, and the number of years of experience as a registered nurse, they then completed the Tennessee Self-Concept Scale. Scores were then compared using independent t-tests applied to the area in which the subject worked, the type of education, and the years of experience. Results …

Underwater Acoustic Wavefront Phase Fluctuations, George L. Vojtech Jr.

OES Theses and Dissertations

In conventional underwater acoustics sound propagation is generally modeled and applied as a coherent or incoherent process. This paper addresses a relatively new theory, that of a range driven increasingly incoherent ray propagation through a real ocean environment, Possible mechanisms are discussed and experimental data presented to reinforce the theory.

Breeding Birds In Cedar Stands In The Great Dismal Swamp, Karen A. Terwilliger, Robert K. Rose

Biological Sciences Faculty Publications

The Great Dismal Swamp located in the coastal plain on the Virginia- North Carolina border, has long been recognized as a vegetationally distinctive region with many unusual geological and biological features. Formerly at least twice the currently estimated size of 85,000 hectares (Carter 1979), the Great Dismal Swamp is still shrinking because of a dropping water table caused by more than 200 years of logging, ditching, and other human activities. In 1973, the Union Camp Corporation donated a 19,871-hectare tract located near Suffolk, Virginia. to The Nature Conservancy, which transferred the land to the U.S. Fish and Wildlife Service. This …

A Study To Determine The Effectiveness Of The Vocational Resource Program In Newport News Public Schools, Newport News, Virginia, Maury Eugene Middleton

OTS Master's Level Projects & Papers

The objectives of this research were: 1. To determine to what extent the services were being used and if they were not, why; 2. To determine the usefulness of the services provided by the Vocational Resource Program; 3. To determine the desired needs of the teachers that were covered by the Vocational Resource Program; 4. To determine the effectiveness of the vocational aides.

Assessment Criteria For Special Education Students In Vocational Education, Joyce A. Francis

OTS Master's Level Projects & Papers

The basic research questions of this study are as follows: 1. What are the exit competencies for a given learning disabled according to the student's career/vocational goals and/or needs? 2. Is it possible for a special education student to be placed in a vocational learning environment with their peers that are "normal" (mainstreaming)? 3. Can a special education student be productive during this period of mainstreaming?

Review Of Upwelling Off The Southeastern United States And Its Effect On Continental-Shelf Nutrient Concentrations And Primary Productivity, Larry P. Atkinson, James A. Yonder, Thomas N. Lee

CCPO Publications

Gulf Stream induced upwelling occurs along the length of the southeastern United States continental shelf break. Upwelling events are produced by northward propagating Gulf Streams frontal meanders and eddies and travel northwards with these features. Meanders and eddies occur throughout the year in a period band of 2-14 days; however, resultant upwellings can affect the shelf quite differently. During fall, winter, and spring, upwelling is restricted to the outer shelf by cross-shelf density distributions, but in the summer upwelled water may penetrate across as a subsurface intrusion if aided by upwelling-favorable winds. If water does penetrate across the shelf, it …

Coastal Upwelling Off The Rias Bajas, Galicia, Northwest Spain I: Hydrographic Studies, J. O. Blanton, L. P. Atkinson, F. Fernandez De Castillejo, A. Lavin Montero

CCPO Publications

Coastal upwelling occurs off the Rias Bajas of Spain between April and October. Superimposed on large-scale upwelling is a mesoscale regime of enhanced upwelling induced by topographic influences. We show that the region surrounding Cape Finisterre has intensified topographically induced upwelling.

The rias have a relatively unobstructed connection with the open ocean. Upwelling of high nitrate water on the continental shelf by Ekman transport sets up pressure gradients at the mouth of the rias that induce upwelled water to flow into the rias. Deep water in the rias responds directly to cycles of upwelling and downwelling on the continental shelf.

The Marine Biogeochemistry Of Selenium: A Re-Evaluation, Gregory A. Cutter, Kenneth W. Bruland

OES Faculty Publications

Vertical and horizontal profiles from the North and South Pacific Oceans demonstrate the existence of three species of dissolved selenium: selenite, selenate, and organic selenide (operationally defined). In surface waters, organic selenide makes up about 80% of the total dissolved selenium, selenite concentrations are uniformly low, and selenate concentrations rise with increased vertical mixing. The organic selenide maximum (thought to consist of seleno-amino acids in peptides) coincides with the maxima of primary productivity, pigments, bioluminescence, and dissolved free amino acids. Deep ocean waters are enriched in selenite and selenate, while organic selenide is nondetectable. In suboxic waters of the tropical …

Episodic Nutrient Supply To A Kelp Forest Ecosystem In Southern California, Richard C. Zimmerman, James N. Kremer

OES Faculty Publications

Temporal patterns of nutrient input into a Southern California kelp forest were measured using traditional hydrocast sampling coupled with high frequency temperature profiling. Patterns of nutrient input were related to growth rates of Macrocystis pyrifera located in an adjacent kelp forest. There were 2 distinct components to the pattern of nutrient availability. The long term, or seasonal, component was consistent with large-scale storm-induced mixing and horizontal advection during winter months. In addition, vertical motions of the thermocline, bringing nutrients into the kelp forest, occurred throughout the year with a frequency of about 2 per day and were strongest during the …

Changes In The Lower Chesapeake Bay Food-Chain In Presence Of The Sea Nettle Chrysaora-Quinquecirrha (Scyphomedusa), David Feigenbaum, Michael Kelly

OES Faculty Publications

The abundance of 4 levels of the lower Chesapeake Bay food chain (Chlorophyll a, herbivores, ctenophore Mnemiopsis leidyi, and Scyphomedusa Chrysaora quinquecirrha) were moni­tored twice weekly at 4 stations from May 10 through Sep 30, 1982 in the Lafayette and Elizabeth Rivers (Virginia). The herbivore standing stock, largely copepods, declined sharply in late May when M. Jeidyi appeared, but rebounded a month later when C. quinquecirrha medusae reduced the ctenophore population. Despite the additional presence of Aurelia aurita (Scyphomedusa) from Jul onward, herbivore abundance remained at moderate levels until the end of the study period. Phytoplankton abundance fluctuated …